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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_DocumentPeriodEndDate" xml:lang="en-US">Document Period End Date</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityRegistrantName" xml:lang="en-US">Entity Registrant Name</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityFilerCategory" xml:lang="en-US">Entity Filer Category</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityEmergingGrowthCompany" xml:lang="en-US">Entity Emerging Growth Company</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntitySmallBusiness" xml:lang="en-US">Entity Small Business</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_DocumentAnnualReport" xml:lang="en-US">Document Annual Report</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentTransitionReport" xlink:label="loc_dei_DocumentTransitionReport" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_DocumentTransitionReport" xml:lang="en-US">Document Transition Report</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_Security12bTitle" xml:lang="en-US">Title of 12(b) Security</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_SecurityExchangeName" xml:lang="en-US">Security Exchange Name</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityCurrentReportingStatus" xml:lang="en-US">Entity Current Reporting Status</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityInteractiveDataCurrent" xml:lang="en-US">Entity Interactive Data Current</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityFileNumber" xml:lang="en-US">Entity File Number</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="loc_dei_EntityIncorporationStateCountryCode" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityIncorporationStateCountryCode" xml:lang="en-US">Entity Incorporation, State or Country Code</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityTaxIdentificationNumber" xlink:label="loc_dei_EntityTaxIdentificationNumber" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityTaxIdentificationNumber" xml:lang="en-US">Entity Tax Identification Number</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressAddressLine1" xlink:label="loc_dei_EntityAddressAddressLine1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityAddressAddressLine1" xml:lang="en-US">Entity Address, Address Line One</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_LocalPhoneNumber" xml:lang="en-US">Local Phone Number</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityAddressStateOrProvince" xml:lang="en-US">Entity Address, State or Province</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityAddressCityOrTown" xml:lang="en-US">Entity Address, City or Town</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_CityAreaCode" xlink:label="loc_dei_CityAreaCode" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_CityAreaCode" xml:lang="en-US">City Area Code</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressPostalZipCode" xlink:label="loc_dei_EntityAddressPostalZipCode" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityAddressPostalZipCode" xml:lang="en-US">Entity Address, Postal Zip Code</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityCommonStockSharesOutstanding" xml:lang="en-US">Entity Common Stock, Shares Outstanding</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_AmendmentFlag" xml:lang="en-US">Amendment Flag</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_DocumentFiscalYearFocus" xml:lang="en-US">Document Fiscal Year Focus</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_DocumentFiscalPeriodFocus" xml:lang="en-US">Document Fiscal Period Focus</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityCentralIndexKey" xml:lang="en-US">Entity Central Index Key</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_CurrentFiscalYearEndDate" xml:lang="en-US">Current Fiscal Year End Date</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityWellKnownSeasonedIssuer" xml:lang="en-US">Entity Well-known Seasoned Issuer</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityVoluntaryFilers" xlink:label="loc_dei_EntityVoluntaryFilers" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityVoluntaryFilers" xml:lang="en-US">Entity Voluntary Filers</label>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityPublicFloat" xlink:label="loc_dei_EntityPublicFloat" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_dei_EntityPublicFloat" xml:lang="en-US">Entity Public Float</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementOfFinancialPositionAbstract" xml:lang="en-US">Statement of Financial Position [Abstract]</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsAbstract" xml:lang="en-US">Assets [Abstract]</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AssetsAbstract" xml:lang="en-US">Assets:</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_Assets" xml:lang="en-US">Total assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Assets" xlink:to="lab_us-gaap_Assets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xml:lang="en-US">Assets, Current [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xml:lang="en-US">Current assets:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrentAbstract" xlink:to="lab_us-gaap_AssetsCurrentAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xml:lang="en-US">Accounts Receivable, Net, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xml:lang="en-US">Accounts receivable, net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xml:lang="en-US">Accounts receivable, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent" xlink:to="lab_us-gaap_AccountsReceivableNetCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsCurrent" xml:lang="en-US">Assets, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_AssetsCurrent" xml:lang="en-US">Total current assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrent" xlink:to="lab_us-gaap_AssetsCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xml:lang="en-US">Cash and Cash Equivalents, at Carrying Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xml:lang="en-US">Cash and cash equivalents</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HeldToMaturitySecuritiesCurrent" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HeldToMaturitySecuritiesCurrent" xml:lang="en-US">Debt Securities, Held-to-maturity, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_HeldToMaturitySecuritiesCurrent" xml:lang="en-US">Short-term investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesCurrent" xlink:to="lab_us-gaap_HeldToMaturitySecuritiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaap_OtherAssetsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherAssetsCurrent" xml:lang="en-US">Other Assets, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherAssetsCurrent" xml:lang="en-US">Other current assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsCurrent" xlink:to="lab_us-gaap_OtherAssetsCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaap_PrepaidExpenseCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PrepaidExpenseCurrent" xml:lang="en-US">Prepaid Expense, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PrepaidExpenseCurrent" xml:lang="en-US">Prepaid expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidExpenseCurrent" xlink:to="lab_us-gaap_PrepaidExpenseCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedCashCurrent" xlink:label="loc_us-gaap_RestrictedCashCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RestrictedCashCurrent" xml:lang="en-US">Restricted Cash, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RestrictedCashCurrent" xml:lang="en-US">Restricted cash</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedCashCurrent" xlink:to="lab_us-gaap_RestrictedCashCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Assets, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xml:lang="en-US">Assets held for sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:to="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xml:lang="en-US">Finite-Lived Intangible Assets, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xml:lang="en-US">Intangible assets, net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xml:lang="en-US">Net Carrying Value</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_Goodwill" xml:lang="en-US">Goodwill</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_Goodwill" xml:lang="en-US">Goodwill</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Goodwill" xlink:to="lab_us-gaap_Goodwill" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HeldToMaturitySecuritiesNoncurrent" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HeldToMaturitySecuritiesNoncurrent" xml:lang="en-US">Debt Securities, Held-to-maturity, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_HeldToMaturitySecuritiesNoncurrent" xml:lang="en-US">Investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesNoncurrent" xlink:to="lab_us-gaap_HeldToMaturitySecuritiesNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xml:lang="en-US">Other Assets, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xml:lang="en-US">Other assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsNoncurrent" xlink:to="lab_us-gaap_OtherAssetsNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet" xml:lang="en-US">Property, Plant and Equipment, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet" xml:lang="en-US">Property and equipment, net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet" xml:lang="en-US">Property and equipment, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xml:lang="en-US">Operating Lease, Right-of-Use Asset</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xml:lang="en-US">Operating lease right-of-use&#160;assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xml:lang="en-US">Operating lease right-of-use assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="lab_us-gaap_OperatingLeaseRightOfUseAsset" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Assets, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" xml:lang="en-US">Assets held for sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xml:lang="en-US">Deferred Tax Assets, Net, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xml:lang="en-US">Deferred income tax assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" xlink:to="lab_us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xml:lang="en-US">Liabilities and Equity [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xml:lang="en-US">LIABILITIES &amp; SHAREHOLDERS' EQUITY</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommitmentsAndContingencies" xml:lang="en-US">Commitments and Contingencies</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommitmentsAndContingencies" xml:lang="en-US">Commitments and contingencies</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingencies" xlink:to="lab_us-gaap_CommitmentsAndContingencies" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesNoncurrent" xml:lang="en-US">Deferred Tax Liabilities, Net, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesNoncurrent" xml:lang="en-US">Deferred income tax liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_Liabilities" xml:lang="en-US">Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_Liabilities" xml:lang="en-US">Total liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Liabilities" xlink:to="lab_us-gaap_Liabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xml:lang="en-US">Liabilities and Equity</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xml:lang="en-US">Total liabilities and shareholders' equity</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquity" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xml:lang="en-US">Liabilities, Current [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xml:lang="en-US">Current liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="lab_us-gaap_LiabilitiesCurrentAbstract" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" xlink:label="loc_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" xml:lang="en-US">Accounts Payable and Accrued Liabilities Excluding Accrued Income Taxes Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" xml:lang="en-US">Accounts payable and accrued expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" xlink:to="lab_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccountsPayableAndAccruedLiabilitiesExcludingAccruedIncomeTaxesCurrent" xml:lang="en-US">Accounts payable and accrued liabilities excluding accrued income taxes current.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccruedIncomeTaxesCurrent" xml:lang="en-US">Accrued Income Taxes, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccruedIncomeTaxesCurrent" xml:lang="en-US">Income taxes payable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedIncomeTaxesCurrent" xlink:to="lab_us-gaap_AccruedIncomeTaxesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesCurrent" xml:lang="en-US">Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_LiabilitiesCurrent" xml:lang="en-US">Total current liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrent" xlink:to="lab_us-gaap_LiabilitiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xml:lang="en-US">Finance Lease, Liability, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xml:lang="en-US">Current portion of finance lease liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xml:lang="en-US">Less: Current portion</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityCurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xml:lang="en-US">Operating Lease, Liability, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xml:lang="en-US">Current portion of operating lease liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xml:lang="en-US">Current portion of operating lease liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xml:lang="en-US">Less: Current obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xml:lang="en-US">Liabilities held for sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:to="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" xlink:label="loc_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" xml:lang="en-US">Long Term Debt and Capital Lease Obligations Excluding Long Term Line of Credit</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" xml:lang="en-US">Long-term debt and finance lease liabilities, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" xlink:to="lab_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_LongTermDebtAndCapitalLeaseObligationsExcludingLongTermLineOfCredit" xml:lang="en-US">Long term debt and capital lease obligations excluding long term line of credit.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermLineOfCredit" xlink:label="loc_us-gaap_LongTermLineOfCredit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LongTermLineOfCredit" xml:lang="en-US">Long-term Line of Credit, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LongTermLineOfCredit" xml:lang="en-US">Line of credit</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermLineOfCredit" xlink:to="lab_us-gaap_LongTermLineOfCredit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" xlink:label="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" xml:lang="en-US">Malpractice Loss Contingency, Accrual, Undiscounted, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" xml:lang="en-US">Long-term professional liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" xlink:to="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xml:lang="en-US">Other Liabilities, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xml:lang="en-US">Other liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:to="lab_us-gaap_OtherLiabilitiesNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xml:lang="en-US">Stockholders' Equity Attributable to Parent [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xml:lang="en-US">Shareholders' equity:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityAbstract" xlink:to="lab_us-gaap_StockholdersEquityAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xml:lang="en-US">Additional Paid in Capital, Common Stock</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xml:lang="en-US">Additional paid-in capital</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:to="lab_us-gaap_AdditionalPaidInCapitalCommonStock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockValue" xml:lang="en-US">Common Stock, Value, Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_CommonStockValue" xml:lang="en-US">Common stock; $.01 par value; 200,000 shares authorized; 84,248 and 87,820 shares issued and outstanding, respectively</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockValue" xlink:to="lab_us-gaap_CommonStockValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PreferredStockValue" xml:lang="en-US">Preferred Stock, Value, Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PreferredStockValue" xml:lang="en-US">Preferred stock; $.01 par value; 1,000 shares authorized; none issued</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockValue" xlink:to="lab_us-gaap_PreferredStockValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xml:lang="en-US">Retained Earnings (Accumulated Deficit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xml:lang="en-US">Retained earnings</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="lab_us-gaap_RetainedEarningsAccumulatedDeficit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockholdersEquity" xml:lang="en-US">Stockholders' Equity Attributable to Parent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_StockholdersEquity" xml:lang="en-US">Total shareholders' equity</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquity" xlink:to="lab_us-gaap_StockholdersEquity" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xml:lang="en-US">Operating Lease, Liability, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xml:lang="en-US">Long-term operating lease liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xml:lang="en-US">Long-term portion of operating lease liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xml:lang="en-US">Long-term portion of operating leases</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xml:lang="en-US">Liabilities held for sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xlink:to="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xml:lang="en-US">Common Stock, Par or Stated Value Per Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xml:lang="en-US">Common stock, par value</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="lab_us-gaap_CommonStockParOrStatedValuePerShare" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xml:lang="en-US">Common Stock, Shares Authorized</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xml:lang="en-US">Common stock, shares authorized</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xml:lang="en-US">Common stock, aggregate shares authorized</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesAuthorized" xlink:to="lab_us-gaap_CommonStockSharesAuthorized" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockSharesIssued" xml:lang="en-US">Common Stock, Shares, Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockSharesIssued" xml:lang="en-US">Common stock, shares issued</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesIssued" xlink:to="lab_us-gaap_CommonStockSharesIssued" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xml:lang="en-US">Common Stock, Shares, Outstanding</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xml:lang="en-US">Common stock, shares outstanding</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesOutstanding" xlink:to="lab_us-gaap_CommonStockSharesOutstanding" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PreferredStockParOrStatedValuePerShare" xml:lang="en-US">Preferred Stock, Par or Stated Value Per Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PreferredStockParOrStatedValuePerShare" xml:lang="en-US">Preferred stock, par value</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="lab_us-gaap_PreferredStockParOrStatedValuePerShare" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized" xml:lang="en-US">Preferred Stock, Shares Authorized</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized" xml:lang="en-US">Preferred stock, shares authorized</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesAuthorized" xlink:to="lab_us-gaap_PreferredStockSharesAuthorized" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PreferredStockSharesIssued" xml:lang="en-US">Preferred Stock, Shares Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PreferredStockSharesIssued" xml:lang="en-US">Preferred stock, issued</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesIssued" xlink:to="lab_us-gaap_PreferredStockSharesIssued" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:label="loc_us-gaap_IncomeStatementAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeStatementAbstract" xml:lang="en-US">Income Statement [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="lab_us-gaap_IncomeStatementAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xml:lang="en-US">Earnings Per Share [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xml:lang="en-US">Net (loss) income:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareAbstract" xlink:to="lab_us-gaap_EarningsPerShareAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerShareBasic" xml:lang="en-US">Earnings Per Share, Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_EarningsPerShareBasic" xml:lang="en-US">Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="lab_us-gaap_EarningsPerShareBasic" xml:lang="en-US">Earnings (loss) per share, Basic</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasic" xlink:to="lab_us-gaap_EarningsPerShareBasic" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xml:lang="en-US">Earnings Per Share, Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xml:lang="en-US">Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xml:lang="en-US">Earnings (loss) per share, Diluted</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareDiluted" xlink:to="lab_us-gaap_EarningsPerShareDiluted" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" xml:lang="en-US">Earnings Per Share, Basic, Other Disclosures [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" xml:lang="en-US">Weighted average common shares:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" xlink:to="lab_us-gaap_EarningsPerShareBasicOtherDisclosuresAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xml:lang="en-US">Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xml:lang="en-US">Weighted average number of common and common equivalent shares outstanding</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xml:lang="en-US">Weighted average shares, Diluted</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xml:lang="en-US">Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xml:lang="en-US">Weighted average number of common shares outstanding</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xml:lang="en-US">Weighted average shares, Basic</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xml:lang="en-US">Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xml:lang="en-US">(Loss) income from continuing operations before income taxes</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xml:lang="en-US">Income&#160;(loss) from continuing operations&#160;before income taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromEquityMethodInvestments" xml:lang="en-US">Income (Loss) from Equity Method Investments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromEquityMethodInvestments" xml:lang="en-US">Equity in earnings of unconsolidated affiliates</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromEquityMethodInvestments" xlink:to="lab_us-gaap_IncomeLossFromEquityMethodInvestments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xml:lang="en-US">Income Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xml:lang="en-US">Income tax benefit (provision)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xml:lang="en-US">Income tax provision, Total</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xml:lang="en-US">Income tax (provision) benefit</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InterestExpense" xml:lang="en-US">Interest Expense</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_InterestExpense" xml:lang="en-US">Interest expense</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestExpense" xlink:to="lab_us-gaap_InterestExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentIncomeNet" xlink:label="loc_us-gaap_InvestmentIncomeNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentIncomeNet" xml:lang="en-US">Investment Income, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InvestmentIncomeNet" xml:lang="en-US">Investment and other income</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentIncomeNet" xlink:to="lab_us-gaap_InvestmentIncomeNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NonoperatingIncomeExpense" xml:lang="en-US">Nonoperating Income (Expense)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NonoperatingIncomeExpense" xml:lang="en-US">Total non-operating expenses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NonoperatingIncomeExpense" xml:lang="en-US">Total non-operating expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NonoperatingIncomeExpense" xlink:to="lab_us-gaap_NonoperatingIncomeExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingExpensesAbstract" xml:lang="en-US">Operating Expenses [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingExpensesAbstract" xml:lang="en-US">Operating expenses:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingExpensesAbstract" xlink:to="lab_us-gaap_OperatingExpensesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DepreciationDepletionAndAmortization" xml:lang="en-US">Depreciation, Depletion and Amortization</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DepreciationDepletionAndAmortization" xml:lang="en-US">Depreciation and amortization</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DepreciationDepletionAndAmortization" xlink:to="lab_us-gaap_DepreciationDepletionAndAmortization" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GeneralAndAdministrativeExpense" xml:lang="en-US">General and Administrative Expense</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GeneralAndAdministrativeExpense" xml:lang="en-US">General and administrative expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GeneralAndAdministrativeExpense" xlink:to="lab_us-gaap_GeneralAndAdministrativeExpense" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PracticeSalariesAndBenefits" xlink:label="loc_md_PracticeSalariesAndBenefits" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PracticeSalariesAndBenefits" xml:lang="en-US">Practice Salaries and Benefits</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PracticeSalariesAndBenefits" xml:lang="en-US">Practice salaries and benefits</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PracticeSalariesAndBenefits" xlink:to="lab_md_PracticeSalariesAndBenefits" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PracticeSalariesAndBenefits" xml:lang="en-US">Practice salaries and benefits.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PracticeSuppliesAndOtherOperatingExpenses" xlink:label="loc_md_PracticeSuppliesAndOtherOperatingExpenses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PracticeSuppliesAndOtherOperatingExpenses" xml:lang="en-US">Practice Supplies And Other Operating Expenses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PracticeSuppliesAndOtherOperatingExpenses" xml:lang="en-US">Practice supplies and other operating expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PracticeSuppliesAndOtherOperatingExpenses" xlink:to="lab_md_PracticeSuppliesAndOtherOperatingExpenses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PracticeSuppliesAndOtherOperatingExpenses" xml:lang="en-US">The aggregate amount of supplies and other operating expenses directly attributable to the physician practices.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillImpairmentLoss" xml:lang="en-US">Goodwill, Impairment Loss</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_GoodwillImpairmentLoss" xml:lang="en-US">Goodwill impairment</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="lab_us-gaap_GoodwillImpairmentLoss" xml:lang="en-US">Non cash impairment charge of goodwill</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillImpairmentLoss" xlink:to="lab_us-gaap_GoodwillImpairmentLoss" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RestructuringCharges" xml:lang="en-US">Restructuring Charges</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_RestructuringCharges" xml:lang="en-US">Transformational and restructuring related expenses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RestructuringCharges" xml:lang="en-US">Transformational and restructuring related expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestructuringCharges" xlink:to="lab_us-gaap_RestructuringCharges" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingExpenses" xml:lang="en-US">Operating Expenses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_OperatingExpenses" xml:lang="en-US">Total operating expenses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingExpenses" xml:lang="en-US">Total operating expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingExpenses" xlink:to="lab_us-gaap_OperatingExpenses" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingIncomeLoss" xml:lang="en-US">Operating Income (Loss)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_OperatingIncomeLoss" xml:lang="en-US">(Loss) income from operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingIncomeLoss" xml:lang="en-US">Income (loss) from operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingIncomeLoss" xlink:to="lab_us-gaap_OperatingIncomeLoss" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xml:lang="en-US">Revenue from Contract with Customer, Including Assessed Tax</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xml:lang="en-US">Net revenue</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">(Loss) income from continuing operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">Income (loss) from continuing operations</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xml:lang="en-US">Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xml:lang="en-US">(Loss) income from discontinued operations, net of tax</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xml:lang="en-US">Loss (income) from discontinued operations</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetIncomeLoss" xml:lang="en-US">Net Income (Loss) Attributable to Parent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetIncomeLoss" xml:lang="en-US">Net (loss) income</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_NetIncomeLoss" xml:lang="en-US">Net income (loss)</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLoss" xlink:to="lab_us-gaap_NetIncomeLoss" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" xlink:label="loc_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" xml:lang="en-US">Income Loss from Continuing Operations Per Basic and Diluted Share [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" xml:lang="en-US">(Loss) income from continuing operations:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" xlink:to="lab_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_IncomelossFromContinuingOperationsPerBasicAndDilutedShareAbstract" xml:lang="en-US">It represents Income (Loss) from continuing operations, per basic and diluted share</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xml:lang="en-US">Income (Loss) from Continuing Operations, Per Basic Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xml:lang="en-US">Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xml:lang="en-US">Income (loss) from continuing operations, Basic</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xml:lang="en-US">Income (Loss) from Continuing Operations, Per Diluted Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xml:lang="en-US">Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xml:lang="en-US">Income (loss) from continuing operations, Diluted</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsAndDisposalOfDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShareAbstract" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsAndDisposalOfDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShareAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsAndDisposalOfDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShareAbstract" xml:lang="en-US">Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic and Diluted Share [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsAndDisposalOfDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShareAbstract" xml:lang="en-US">Income (loss) from discontinued operations:</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xml:lang="en-US">Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xml:lang="en-US">Basic</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xml:lang="en-US">(Loss) income from discontinued operations, Basic</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" xlink:to="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xml:lang="en-US">Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xml:lang="en-US">Diluted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xml:lang="en-US">(Loss) income from discontinued operations, Diluted</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" xlink:to="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementOfStockholdersEquityAbstract" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract" xml:lang="en-US">Statement of Stockholders' Equity [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfStockholdersEquityAbstract" xlink:to="lab_us-gaap_StatementOfStockholdersEquityAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementTable" xml:lang="en-US">Statement [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StatementTable" xml:lang="en-US">Statement [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementTable" xlink:to="lab_us-gaap_StatementTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xml:lang="en-US">Equity Components [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xml:lang="en-US">Equity Components [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="lab_us-gaap_StatementEquityComponentsAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EquityComponentDomain" xml:lang="en-US">Equity Component [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EquityComponentDomain" xml:lang="en-US">Equity Component [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="lab_us-gaap_EquityComponentDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xml:lang="en-US">Additional Paid-in Capital [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xml:lang="en-US">Additional Paid-in Capital [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:to="lab_us-gaap_AdditionalPaidInCapitalMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockMember" xml:lang="en-US">Common Stock [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockMember" xml:lang="en-US">Common Stock [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockMember" xlink:to="lab_us-gaap_CommonStockMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RetainedEarningsMember" xml:lang="en-US">Retained Earnings [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RetainedEarningsMember" xml:lang="en-US">Retained Earnings [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsMember" xlink:to="lab_us-gaap_RetainedEarningsMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementLineItems" xml:lang="en-US">Statement [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StatementLineItems" xml:lang="en-US">Statement [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="lab_us-gaap_StatementLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xml:lang="en-US">Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xml:lang="en-US">Stock-based compensation expense</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:to="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaap_SharesIssued" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharesIssued" xml:lang="en-US">Shares, Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_SharesIssued" xml:lang="en-US">Balance, Shares</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_SharesIssued" xml:lang="en-US">Balance, Shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharesIssued" xlink:to="lab_us-gaap_SharesIssued" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">Balance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xml:lang="en-US">Balance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" xlink:label="loc_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" xml:lang="en-US">Stock Issued During Period Shares Restricted Stock Acquisition Consideration</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" xml:lang="en-US">Issuance of restricted stock for acquisition consideration, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" xlink:to="lab_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_StockIssuedDuringPeriodSharesRestrictedStockAcquisitionConsideration" xml:lang="en-US">Stock issued during period shares restricted stock acquisition consideration.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xml:lang="en-US">Stock Issued During Period, Shares, Restricted Stock Award, Forfeited</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xml:lang="en-US">Forfeitures of restricted stock, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xml:lang="en-US">Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xml:lang="en-US">Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xml:lang="en-US">Stock Issued During Period, Shares, Share-based Compensation, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xml:lang="en-US">Issuance of restricted stock, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_StockIssuedDuringPeriodSharesStockSwaps" xlink:label="loc_md_StockIssuedDuringPeriodSharesStockSwaps" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_StockIssuedDuringPeriodSharesStockSwaps" xml:lang="en-US">Stock Issued During Period, Shares, Stock Swaps</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_StockIssuedDuringPeriodSharesStockSwaps" xml:lang="en-US">Stock swaps, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_StockIssuedDuringPeriodSharesStockSwaps" xlink:to="lab_md_StockIssuedDuringPeriodSharesStockSwaps" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_StockIssuedDuringPeriodSharesStockSwaps" xml:lang="en-US">Stock issued during period shares stock swaps.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" xlink:label="loc_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" xml:lang="en-US">Stock Issued During Period Value Restricted Stock Acquisition Consideration</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" xml:lang="en-US">Issuance of restricted stock for acquisition consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" xlink:to="lab_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_StockIssuedDuringPeriodValueRestrictedStockAcquisitionConsideration" xml:lang="en-US">Stock issued during period value restricted stock acquisition consideration.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" xml:lang="en-US">Stock Issued During Period, Value, Restricted Stock Award, Forfeitures</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" xml:lang="en-US">Forfeitures of restricted stock</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xml:lang="en-US">Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xml:lang="en-US">Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" xml:lang="en-US">Stock Issued During Period, Value, Share-based Compensation, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" xml:lang="en-US">Issuance of restricted stock</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_StockIssuedDuringPeriodValueStockSwaps" xlink:label="loc_md_StockIssuedDuringPeriodValueStockSwaps" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_StockIssuedDuringPeriodValueStockSwaps" xml:lang="en-US">Stock Issued During Period Value Stock Swaps</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_StockIssuedDuringPeriodValueStockSwaps" xml:lang="en-US">Stock swaps</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_StockIssuedDuringPeriodValueStockSwaps" xlink:to="lab_md_StockIssuedDuringPeriodValueStockSwaps" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_StockIssuedDuringPeriodValueStockSwaps" xml:lang="en-US">Stock issued during period value stock swaps.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares" xml:lang="en-US">Stock Repurchased During Period, Shares</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares" xml:lang="en-US">Repurchased common stock, shares</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares" xml:lang="en-US">Repurchased common stock, shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchasedDuringPeriodShares" xlink:to="lab_us-gaap_StockRepurchasedDuringPeriodShares" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue" xml:lang="en-US">Stock Repurchased During Period, Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue" xml:lang="en-US">Repurchased common stock</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue" xml:lang="en-US">Common stock repurchased</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchasedDuringPeriodValue" xlink:to="lab_us-gaap_StockRepurchasedDuringPeriodValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xml:lang="en-US">Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xml:lang="en-US">Unrealized holding gain on investments, net of tax</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:to="lab_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract" xml:lang="en-US">Statement of Cash Flows [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract" xlink:to="lab_us-gaap_StatementOfCashFlowsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xml:lang="en-US">Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xml:lang="en-US">Cash, cash equivalents and restricted cash at beginning of year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xml:lang="en-US">Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xml:lang="en-US">Cash and cash equivalents and restricted cash at end of year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xml:lang="en-US">Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xml:lang="en-US">Net increase (decrease) in cash and cash equivalents</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xml:lang="en-US">Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xml:lang="en-US">Non-cash investing and financing activities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:to="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xml:lang="en-US">Capital Expenditures Incurred but Not yet Paid</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xml:lang="en-US">Property and equipment included in accounts payable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:to="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CapitalLeaseObligationsIncurred" xml:lang="en-US">Capital Lease Obligations Incurred</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CapitalLeaseObligationsIncurred" xml:lang="en-US">Equipment financed through finance leases</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CapitalLeaseObligationsIncurred" xlink:to="lab_us-gaap_CapitalLeaseObligationsIncurred" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssued1" xlink:label="loc_us-gaap_StockIssued1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssued1" xml:lang="en-US">Stock Issued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssued1" xml:lang="en-US">Value of common stock issued for acquisitions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssued1" xlink:to="lab_us-gaap_StockIssued1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xml:lang="en-US">Net Cash Provided by (Used in) Financing Activities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xml:lang="en-US">Cash flows from financing activities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xml:lang="en-US">Net Cash Provided by (Used in) Financing Activities, Continuing Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xml:lang="en-US">Net cash (used in) provided by financing activities&#8212;continuing operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xml:lang="en-US">Payment for Contingent Consideration Liability, Financing Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xml:lang="en-US">Payments of contingent consideration liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xlink:to="lab_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" xml:lang="en-US">Payments for Repurchase of Common Stock</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" xml:lang="en-US">Repurchases of common stock</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:to="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsOfFinancingCosts" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsOfFinancingCosts" xml:lang="en-US">Payments of Financing Costs</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsOfFinancingCosts" xml:lang="en-US">Payments for financing costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfFinancingCosts" xlink:to="lab_us-gaap_PaymentsOfFinancingCosts" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfCommonStock" xml:lang="en-US">Proceeds from Issuance of Common Stock</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfCommonStock" xml:lang="en-US">Proceeds from issuance of common stock</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfCommonStock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" xml:lang="en-US">Proceeds from Issuance of Senior Long-term Debt</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" xml:lang="en-US">Proceeds from issuance of senior notes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromLinesOfCredit" xml:lang="en-US">Proceeds from Lines of Credit</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsFromLinesOfCredit" xml:lang="en-US">Borrowings on credit agreement</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromLinesOfCredit" xlink:to="lab_us-gaap_ProceedsFromLinesOfCredit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromMinorityShareholders" xlink:label="loc_us-gaap_ProceedsFromMinorityShareholders" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromMinorityShareholders" xml:lang="en-US">Proceeds from Noncontrolling Interests</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsFromMinorityShareholders" xml:lang="en-US">Contribution from noncontrolling interests</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromMinorityShareholders" xlink:to="lab_us-gaap_ProceedsFromMinorityShareholders" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RepaymentsOfLinesOfCredit" xml:lang="en-US">Repayments of Lines of Credit</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_RepaymentsOfLinesOfCredit" xml:lang="en-US">Payments on credit agreement</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfLinesOfCredit" xlink:to="lab_us-gaap_RepaymentsOfLinesOfCredit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xlink:label="loc_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xml:lang="en-US">Repayments of Long-term Capital Lease Obligations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xml:lang="en-US">Payments on finance lease obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xlink:to="lab_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" xml:lang="en-US">Cash Provided by (Used in) Financing Activities, Discontinued Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" xml:lang="en-US">Net cash used in financing activities&#8212;discontinued operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" xlink:to="lab_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xml:lang="en-US">Net Cash Provided by (Used in) Financing Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xml:lang="en-US">Net cash (used in) provided by financing activities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xml:lang="en-US">Cash flows from investing activities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities, Continuing Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xml:lang="en-US">Net cash provided by (used in) investing activities&#8212;continuing operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xml:lang="en-US">Payments for (Proceeds from) Other Investing Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xml:lang="en-US">Other</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:to="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xml:lang="en-US">Payments to Acquire Businesses, Net of Cash Acquired</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xml:lang="en-US">Acquisition payments, net of cash acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:to="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireInvestments" xlink:label="loc_us-gaap_PaymentsToAcquireInvestments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsToAcquireInvestments" xml:lang="en-US">Payments to Acquire Investments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsToAcquireInvestments" xml:lang="en-US">Purchases of investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireInvestments" xlink:to="lab_us-gaap_PaymentsToAcquireInvestments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" xml:lang="en-US">Payments to Acquire Other Property, Plant, and Equipment</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" xml:lang="en-US">Purchases of property and equipment</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" xlink:to="lab_us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xml:lang="en-US">Proceeds from Sale, Maturity and Collection of Investments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xml:lang="en-US">Proceeds from maturities or sales of investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:to="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" xml:lang="en-US">Proceeds from Sales of Business, Affiliate and Productive Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" xml:lang="en-US">Proceeds from sales of businesses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" xlink:to="lab_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xml:lang="en-US">Cash Provided by (Used in) Investing Activities, Discontinued Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xml:lang="en-US">Net cash used in investing activities&#8212;discontinued operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" xlink:to="lab_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xml:lang="en-US">Net cash provided by (used in) investing activities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xml:lang="en-US">Cash flows from operating activities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xml:lang="en-US">Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xml:lang="en-US">Adjustments to reconcile net income to net cash provided from operating activities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AmortizationOfFinancingCostsAndDiscounts" xml:lang="en-US">Amortization of Debt Issuance Costs and Discounts</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AmortizationOfFinancingCostsAndDiscounts" xml:lang="en-US">Amortization of premiums, discounts and issuance costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:to="lab_us-gaap_AmortizationOfFinancingCostsAndDiscounts" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xml:lang="en-US">Deferred Income Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xml:lang="en-US">Deferred income taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherNoncashIncomeExpense" xml:lang="en-US">Other Noncash Income (Expense)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_OtherNoncashIncomeExpense" xml:lang="en-US">Other</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherNoncashIncomeExpense" xlink:to="lab_us-gaap_OtherNoncashIncomeExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensation" xml:lang="en-US">Share-based Compensation</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensation" xml:lang="en-US">Stock-based compensation expense</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensation" xlink:to="lab_us-gaap_ShareBasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xml:lang="en-US">Increase (Decrease) in Operating Capital [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xml:lang="en-US">Changes in assets and liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xml:lang="en-US">Increase (Decrease) in Accounts Payable and Accrued Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xml:lang="en-US">Accounts payable and accrued expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" xml:lang="en-US">Increase (Decrease) in Accounts Receivable</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" xml:lang="en-US">Accounts receivable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsReceivable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xml:lang="en-US">Increase (Decrease) in Income Taxes Payable</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xml:lang="en-US">Income taxes payable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:to="lab_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" xlink:label="loc_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" xml:lang="en-US">Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" xml:lang="en-US">Long-term professional liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" xlink:to="lab_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xml:lang="en-US">Increase (Decrease) in Other Noncurrent Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xml:lang="en-US">Other long-term assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:to="lab_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xml:lang="en-US">Increase (Decrease) in Other Operating Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xml:lang="en-US">Other liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:to="lab_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xml:lang="en-US">Increase (Decrease) in Prepaid Expense and Other Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xml:lang="en-US">Prepaid expenses and other current assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:to="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" xml:lang="en-US">Payment for Contingent Consideration Liability, Operating Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" xml:lang="en-US">Payments of contingent consideration liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" xlink:to="lab_us-gaap_PaymentForContingentConsiderationLiabilityOperatingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProfitLoss" xml:lang="en-US">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ProfitLoss" xml:lang="en-US">Net (loss) income</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProfitLoss" xlink:to="lab_us-gaap_ProfitLoss" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xlink:label="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xml:lang="en-US">Cash Provided by (Used in) Operating Activities, Discontinued Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xml:lang="en-US">Net cash provided by operating activities&#8212;discontinued operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" xlink:to="lab_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xml:lang="en-US">Net cash provided by operating activities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities, Continuing Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xml:lang="en-US">Net cash provided by operating activities&#8212;continuing operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract" xml:lang="en-US">Supplemental Cash Flow Information [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract" xml:lang="en-US">Supplemental disclosure of cash flow information:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract" xlink:to="lab_us-gaap_SupplementalCashFlowInformationAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxesPaidNet" xml:lang="en-US">Income Taxes Paid, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxesPaidNet" xml:lang="en-US">Income taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaidNet" xlink:to="lab_us-gaap_IncomeTaxesPaidNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="loc_us-gaap_InterestPaidNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InterestPaidNet" xml:lang="en-US">Interest Paid, Excluding Capitalized Interest, Operating Activities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InterestPaidNet" xml:lang="en-US">Interest</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaidNet" xlink:to="lab_us-gaap_InterestPaidNet" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" xlink:label="loc_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" xml:lang="en-US">Cash Cash Equivalents Restricted Cash and Restricted Cash Equivalents Discontinued Operations Ending Balance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" xml:lang="en-US">Less cash and cash equivalents of discontinued operations at end of year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" xlink:to="lab_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsDiscontinuedOperationsEndingBalance" xml:lang="en-US">Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; of disposal group and discontinued operations.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xml:lang="en-US">Organization, Consolidation and Presentation of Financial Statements [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NatureOfOperations" xlink:label="loc_us-gaap_NatureOfOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NatureOfOperations" xml:lang="en-US">Nature of Operations [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NatureOfOperations" xml:lang="en-US">General</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NatureOfOperations" xlink:to="lab_us-gaap_NatureOfOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="loc_us-gaap_AccountingPoliciesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountingPoliciesAbstract" xml:lang="en-US">Accounting Policies [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountingPoliciesAbstract" xlink:to="lab_us-gaap_AccountingPoliciesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xml:lang="en-US">Significant Accounting Policies [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xml:lang="en-US">Summary of Significant Accounting Policies</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:to="lab_us-gaap_SignificantAccountingPoliciesTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract" xlink:label="loc_us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract" xml:lang="en-US">Investments, Debt and Equity Securities [Abstract]</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_TextBlockAbstract" xml:lang="en-US">Text Block [Abstract]</label>
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<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccountsReceivableAndNetRevenueDisclosureTextBlock" xlink:label="loc_md_AccountsReceivableAndNetRevenueDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccountsReceivableAndNetRevenueDisclosureTextBlock" xml:lang="en-US">Accounts Receivable And Net Revenue Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccountsReceivableAndNetRevenueDisclosureTextBlock" xml:lang="en-US">Accounts Receivable and Net Revenue</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccountsReceivableAndNetRevenueDisclosureTextBlock" xml:lang="en-US">Accounts receivable and net revenue disclosure.</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAbstract" xml:lang="en-US">Property, Plant and Equipment [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xml:lang="en-US">Property, Plant and Equipment Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xml:lang="en-US">Property and Equipment</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationsAbstract" xlink:label="loc_us-gaap_BusinessCombinationsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationsAbstract" xml:lang="en-US">Business Combinations [Abstract]</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationDisclosureTextBlock" xlink:label="loc_us-gaap_BusinessCombinationDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationDisclosureTextBlock" xml:lang="en-US">Business Combination Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationDisclosureTextBlock" xml:lang="en-US">Business Acquisitions</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xml:lang="en-US">Goodwill and Intangible Assets Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:to="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xml:lang="en-US">Goodwill and Intangible Assets Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xml:lang="en-US">Goodwill and Intangible Assets</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" xlink:label="loc_us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" xml:lang="en-US">Discontinued Operations and Disposal Groups [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" xlink:to="lab_us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" xml:lang="en-US">Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" xml:lang="en-US">Discontinued Operations</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PayablesAndAccrualsAbstract" xlink:label="loc_us-gaap_PayablesAndAccrualsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PayablesAndAccrualsAbstract" xml:lang="en-US">Payables and Accruals [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PayablesAndAccrualsAbstract" xlink:to="lab_us-gaap_PayablesAndAccrualsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xml:lang="en-US">Accounts Payable and Accrued Liabilities Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xml:lang="en-US">Accounts Payable and Accrued Expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:to="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeasesAbstract" xlink:label="loc_us-gaap_LeasesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LeasesAbstract" xml:lang="en-US">Leases [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeasesAbstract" xlink:to="lab_us-gaap_LeasesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeasesOfLesseeDisclosureTextBlock" xlink:label="loc_us-gaap_LeasesOfLesseeDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LeasesOfLesseeDisclosureTextBlock" xml:lang="en-US">Leases of Lessee Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LeasesOfLesseeDisclosureTextBlock" xml:lang="en-US">Leases of Lessee Disclosure</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeasesOfLesseeDisclosureTextBlock" xlink:to="lab_us-gaap_LeasesOfLesseeDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCareOrganizationsAbstract" xlink:label="loc_us-gaap_HealthCareOrganizationsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCareOrganizationsAbstract" xml:lang="en-US">Health Care Organizations [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCareOrganizationsAbstract" xlink:to="lab_us-gaap_HealthCareOrganizationsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyDisclosureTextBlock" xlink:label="loc_us-gaap_MalpracticeLossContingencyDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyDisclosureTextBlock" xml:lang="en-US">Malpractice Loss Contingency Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyDisclosureTextBlock" xml:lang="en-US">Accrued Professional Liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyDisclosureTextBlock" xlink:to="lab_us-gaap_MalpracticeLossContingencyDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtDisclosureAbstract" xml:lang="en-US">Debt Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureAbstract" xlink:to="lab_us-gaap_DebtDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" xlink:label="loc_us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" xml:lang="en-US">Debt and Capital Leases Disclosures [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" xml:lang="en-US">Line of Credit, Long-Term Debt and Capital Lease Obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" xlink:to="lab_us-gaap_DebtAndCapitalLeasesDisclosuresTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxDisclosureAbstract" xml:lang="en-US">Income Tax Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract" xlink:to="lab_us-gaap_IncomeTaxDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxDisclosureTextBlock" xlink:label="loc_us-gaap_IncomeTaxDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xml:lang="en-US">Income Tax Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xml:lang="en-US">Income Taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxDisclosureTextBlock" xlink:to="lab_us-gaap_IncomeTaxDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareTextBlock" xlink:label="loc_us-gaap_EarningsPerShareTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerShareTextBlock" xml:lang="en-US">Earnings Per Share [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EarningsPerShareTextBlock" xml:lang="en-US">Common and Common Equivalent Shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareTextBlock" xlink:to="lab_us-gaap_EarningsPerShareTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xml:lang="en-US">Disclosure of Compensation Related Costs, Share-based Payments [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:to="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xml:lang="en-US">Disclosure of Compensation Related Costs, Share-based Payments [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xml:lang="en-US">Stock Incentive Plans and Stock Purchase Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:to="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CommonStockRepurchasesTextBlock" xlink:label="loc_md_CommonStockRepurchasesTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CommonStockRepurchasesTextBlock" xml:lang="en-US">Common Stock Repurchases [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CommonStockRepurchasesTextBlock" xml:lang="en-US">Common Stock Repurchase Programs</label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CommonStockRepurchasesTextBlock" xml:lang="en-US">Entire disclosure of common stock repurchases.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:label="loc_us-gaap_CompensationAndRetirementDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CompensationAndRetirementDisclosureAbstract" xml:lang="en-US">Retirement Benefits [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:to="lab_us-gaap_CompensationAndRetirementDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xml:lang="en-US">Pension and Other Postretirement Benefits Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xml:lang="en-US">Retirement Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:to="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xml:lang="en-US">Commitments and Contingencies Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xml:lang="en-US">Commitments and Contingencies Disclosure [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xml:lang="en-US">Commitments and Contingencies</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:label="loc_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xml:lang="en-US">Quarterly Financial Information Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" xlink:to="lab_us-gaap_QuarterlyFinancialInformationDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_QuarterlyFinancialInformationTextBlock" xlink:label="loc_us-gaap_QuarterlyFinancialInformationTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_QuarterlyFinancialInformationTextBlock" xml:lang="en-US">Quarterly Financial Information [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_QuarterlyFinancialInformationTextBlock" xml:lang="en-US">Selected Quarterly Financial Information</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_QuarterlyFinancialInformationTextBlock" xlink:to="lab_us-gaap_QuarterlyFinancialInformationTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationsPolicy" xlink:label="loc_us-gaap_BusinessCombinationsPolicy" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationsPolicy" xml:lang="en-US">Business Combinations Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_BusinessCombinationsPolicy" xml:lang="en-US">Business Acquisitions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationsPolicy" xlink:to="lab_us-gaap_BusinessCombinationsPolicy" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:label="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xml:lang="en-US">Cash and Cash Equivalents, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xml:lang="en-US">Cash and Cash Equivalents</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:to="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" xlink:label="loc_us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" xml:lang="en-US">Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" xml:lang="en-US">Restricted Cash</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" xlink:to="lab_us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CommonStockShareRepurchasesPolicyTextBlock" xlink:label="loc_md_CommonStockShareRepurchasesPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CommonStockShareRepurchasesPolicyTextBlock" xml:lang="en-US">Common Stock Share Repurchases [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CommonStockShareRepurchasesPolicyTextBlock" xml:lang="en-US">Common Stock Repurchases</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CommonStockShareRepurchasesPolicyTextBlock" xlink:to="lab_md_CommonStockShareRepurchasesPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CommonStockShareRepurchasesPolicyTextBlock" xml:lang="en-US">Common stock share repurchases policy.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConsolidationPolicyTextBlock" xlink:label="loc_us-gaap_ConsolidationPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock" xml:lang="en-US">Consolidation, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock" xml:lang="en-US">Principles of Presentation</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConsolidationPolicyTextBlock" xlink:to="lab_us-gaap_ConsolidationPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerSharePolicyTextBlock" xlink:label="loc_us-gaap_EarningsPerSharePolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xml:lang="en-US">Earnings Per Share, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xml:lang="en-US">Net Income Per Common Share</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerSharePolicyTextBlock" xlink:to="lab_us-gaap_EarningsPerSharePolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:label="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" xml:lang="en-US">Fair Value of Financial Instruments, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" xml:lang="en-US">Fair Value Measurements</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xml:lang="en-US">Goodwill and Intangible Assets, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xml:lang="en-US">Goodwill and Other Intangible Assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:to="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:label="loc_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xml:lang="en-US">Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xml:lang="en-US">Long-Lived Assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:to="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxPolicyTextBlock" xlink:label="loc_us-gaap_IncomeTaxPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xml:lang="en-US">Income Tax, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xml:lang="en-US">Income Taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxPolicyTextBlock" xlink:to="lab_us-gaap_IncomeTaxPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentPolicyTextBlock" xlink:label="loc_us-gaap_InvestmentPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentPolicyTextBlock" xml:lang="en-US">Investment, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InvestmentPolicyTextBlock" xml:lang="en-US">Investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentPolicyTextBlock" xlink:to="lab_us-gaap_InvestmentPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:label="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xml:lang="en-US">New Accounting Pronouncements, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xml:lang="en-US">New Accounting Pronouncements</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:to="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ProfessionalLiabilityCoveragePolicyTextBlock" xlink:label="loc_md_ProfessionalLiabilityCoveragePolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ProfessionalLiabilityCoveragePolicyTextBlock" xml:lang="en-US">Professional Liability Coverage Policy [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ProfessionalLiabilityCoveragePolicyTextBlock" xml:lang="en-US">Professional Liability Coverage</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ProfessionalLiabilityCoveragePolicyTextBlock" xlink:to="lab_md_ProfessionalLiabilityCoveragePolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ProfessionalLiabilityCoveragePolicyTextBlock" xml:lang="en-US">Professional liability coverage policy.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xml:lang="en-US">Property, Plant and Equipment, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xml:lang="en-US">Property and Equipment</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" xlink:label="loc_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" xml:lang="en-US">Recently Adopted Accounting Pronouncements [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" xml:lang="en-US">Recently Adopted Accounting Pronouncements</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" xlink:to="lab_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_RecentlyAdoptedAccountingPronouncementsPolicyTextBlock" xml:lang="en-US">Recently adopted accounting pronouncements policy.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRecognitionPolicyTextBlock" xlink:label="loc_us-gaap_RevenueRecognitionPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RevenueRecognitionPolicyTextBlock" xml:lang="en-US">Revenue Recognition, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RevenueRecognitionPolicyTextBlock" xml:lang="en-US">Revenue Recognition</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRecognitionPolicyTextBlock" xlink:to="lab_us-gaap_RevenueRecognitionPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:label="loc_us-gaap_SegmentReportingPolicyPolicyTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" xml:lang="en-US">Segment Reporting, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" xml:lang="en-US">Segment Reporting</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:to="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:label="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xml:lang="en-US">Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xml:lang="en-US">Stock Incentive Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:to="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UseOfEstimates" xlink:label="loc_us-gaap_UseOfEstimates" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UseOfEstimates" xml:lang="en-US">Use of Estimates, Policy [Policy Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UseOfEstimates" xml:lang="en-US">Accounting Estimates and Assumptions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UseOfEstimates" xlink:to="lab_us-gaap_UseOfEstimates" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xml:lang="en-US">Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xml:lang="en-US">Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" xlink:label="loc_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" xml:lang="en-US">Financial Instruments Measured At Carrying Amount Table Text Block</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" xml:lang="en-US">Financial Instruments Measured At Carrying Amount</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" xlink:to="lab_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_FinancialInstrumentsMeasuredAtCarryingAmountTableTextBlock" xml:lang="en-US">Tabular disclosure of financial instruments measured at carrying amount.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xml:lang="en-US">Schedule of Segment Reporting Information, by Segment [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xml:lang="en-US">Schedule of Net Revenue by Service Line</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:to="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AvailableForSaleSecuritiesTextBlock" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesTextBlock" xml:lang="en-US">Available-for-sale Securities [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesTextBlock" xml:lang="en-US">Schedule of Investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesTextBlock" xlink:to="lab_us-gaap_AvailableForSaleSecuritiesTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:label="loc_us-gaap_DisaggregationOfRevenueTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" xml:lang="en-US">Disaggregation of Revenue [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" xml:lang="en-US">Schedule of Net Revenue</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:to="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xml:lang="en-US">Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xml:lang="en-US">Schedule of Accounts Receivable, Net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:to="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" xlink:label="loc_us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" xml:lang="en-US">Schedules of Concentration of Risk, by Risk Factor [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" xml:lang="en-US">Schedule of Percentage of Net Revenue</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" xlink:to="lab_us-gaap_SchedulesOfConcentrationOfRiskByRiskFactorTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xml:lang="en-US">Property, Plant and Equipment [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xml:lang="en-US">Schedule of Property and Equipment</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" xml:lang="en-US">Finite-lived Intangible Assets Amortization Expense [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" xml:lang="en-US">Amortization Expenses for Existing Intangible Assets for the Next Five Years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xml:lang="en-US">Schedule of Finite-Lived Intangible Assets [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xml:lang="en-US">Summary of Intangible Assets, Net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" xlink:label="loc_us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" xml:lang="en-US">Disposal Groups, Including Discontinued Operations [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" xml:lang="en-US">Disposal Groups, Including Discontinued Operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" xlink:to="lab_us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xml:lang="en-US">Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xml:lang="en-US">Schedule of Accounts Payable and Accrued Expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" xlink:label="loc_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" xml:lang="en-US">Operating Lease Related Assets And Liabilities And Other Related Information Table Text Block</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" xml:lang="en-US">Operating Lease Related Assets And Liabilities And Other Related Information</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" xlink:to="lab_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OperatingLeaseRelatedAssetsAndLiabilitiesAndOtherRelatedInformationTableTextBlock" xml:lang="en-US">Tabular disclosure of operating lease related assets and liabilities and other related information.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseCostTableTextBlock" xlink:label="loc_us-gaap_LeaseCostTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xml:lang="en-US">Lease, Cost [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xml:lang="en-US">Lease, Cost</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCostTableTextBlock" xlink:to="lab_us-gaap_LeaseCostTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" xlink:label="loc_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" xml:lang="en-US">Operating Leases Cash Flow Related Information Table Text Block</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" xml:lang="en-US">Operating Leases Cash Flow Related Information</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" xlink:to="lab_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OperatingLeasesCashFlowRelatedInformationTableTextBlock" xml:lang="en-US">Tabular disclosure of operating lease related cash flow information.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xml:lang="en-US">Lessee, Operating Lease, Liability, Maturity [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xml:lang="en-US">Lessee, Operating Lease, Liability, Maturity</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" xlink:label="loc_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" xml:lang="en-US">Schedule Of Accrued Professional Liability [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" xml:lang="en-US">Schedule of Accrued Professional Liability</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" xlink:to="lab_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ScheduleOfAccruedProfessionalLiabilityTableTextBlock" xml:lang="en-US">Schedule of accrued professional liability.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDebtTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock" xml:lang="en-US">Schedule of Debt [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock" xml:lang="en-US">Schedule of Long-Term Debt</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDebtTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfDebtTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" xlink:label="loc_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" xml:lang="en-US">Summary of Estimated Fair Value of Notes Table [Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" xml:lang="en-US">Summary of Estimated Fair Value of Notes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" xlink:to="lab_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_SummaryOfEstimatedFairValueOfNotesTableTextBlock" xml:lang="en-US">Summary of Estimated Fair Value of Notes Table [Text Block]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ScheduleOfFinanceLeaseObligationsTableTextBlock" xlink:label="loc_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" xml:lang="en-US">Schedule Of Finance Lease Obligations [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" xml:lang="en-US">Schedule of Financial Lease Obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" xlink:to="lab_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ScheduleOfFinanceLeaseObligationsTableTextBlock" xml:lang="en-US">Schedule Of Finance Lease Obligations.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xml:lang="en-US">Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xml:lang="en-US">Summary of Components of Income Tax Provision</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xml:lang="en-US">Schedule of Deferred Tax Assets and Liabilities [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xml:lang="en-US">Significant Components of Deferred Income Tax Assets and Liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xml:lang="en-US">Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xml:lang="en-US">Schedule of Differences Between Effective Rate and United States Federal Income Tax Statutory Rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:label="loc_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xml:lang="en-US">Summary of Income Tax Contingencies [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xml:lang="en-US">Schedule of Activity Related to Gross Unrecognized Tax Benefits</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:to="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xml:lang="en-US">Schedule of Weighted Average Number of Shares [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xml:lang="en-US">Schedule of Calculation of Shares Used in Basic and Diluted Net Income Per Share</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xml:lang="en-US">Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xml:lang="en-US">Schedule of Restricted Stock and Deferred Stock Awards</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xml:lang="en-US">Share-based Compensation, Stock Options, Activity [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xml:lang="en-US">Schedule of Activity and Certain Other Information Related to Stock Option Awards</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xml:lang="en-US">Quarterly Financial Information [Table Text Block]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xml:lang="en-US">Summary of Company's Selected Quarterly Financial Information</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_SummaryOfSignificantAccountingPoliciesTable" xlink:label="loc_md_SummaryOfSignificantAccountingPoliciesTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesTable" xml:lang="en-US">Summary Of Significant Accounting Policies [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesTable" xml:lang="en-US">Summary Of Significant Accounting Policies [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_SummaryOfSignificantAccountingPoliciesTable" xlink:to="lab_md_SummaryOfSignificantAccountingPoliciesTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesTable" xml:lang="en-US">Summary Of Significant Accounting Policies [Table]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xml:lang="en-US">Concentration Risk Benchmark [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xml:lang="en-US">Concentration Risk Benchmark [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xml:lang="en-US">Concentration Risk Benchmark [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xml:lang="en-US">Concentration Risk Benchmark [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="lab_us-gaap_ConcentrationRiskBenchmarkDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsReceivableMember" xml:lang="en-US">Accounts Receivable [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccountsReceivableMember" xml:lang="en-US">Accounts Receivable [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableMember" xlink:to="lab_us-gaap_AccountsReceivableMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xml:lang="en-US">Concentration Risk Type [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xml:lang="en-US">Concentration Risk Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:to="lab_us-gaap_ConcentrationRiskByTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xml:lang="en-US">Concentration Risk Type [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xml:lang="en-US">Concentration Risk Type [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:to="lab_us-gaap_ConcentrationRiskTypeDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GovernmentContractsConcentrationRiskMember" xml:lang="en-US">Government Contracts Concentration Risk [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GovernmentContractsConcentrationRiskMember" xml:lang="en-US">Government Contracts Concentration Risk [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GovernmentContractsConcentrationRiskMember" xlink:to="lab_us-gaap_GovernmentContractsConcentrationRiskMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CreditFacilityAxis" xml:lang="en-US">Credit Facility [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CreditFacilityAxis" xml:lang="en-US">Credit Facility [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityAxis" xlink:to="lab_us-gaap_CreditFacilityAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CreditFacilityDomain" xml:lang="en-US">Credit Facility [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CreditFacilityDomain" xml:lang="en-US">Credit Facility [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityDomain" xlink:to="lab_us-gaap_CreditFacilityDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xml:lang="en-US">Property, Plant and Equipment, Type [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xml:lang="en-US">Property, Plant and Equipment, Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xml:lang="en-US">Property, Plant and Equipment, Type [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xml:lang="en-US">Property, Plant and Equipment, Type [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BuildingMember" xlink:label="loc_us-gaap_BuildingMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BuildingMember" xml:lang="en-US">Building [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_BuildingMember" xml:lang="en-US">Buildings [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BuildingMember" xlink:to="lab_us-gaap_BuildingMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ComputerEquipmentMember" xml:lang="en-US">Computer Equipment [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ComputerEquipmentMember" xml:lang="en-US">Computer Equipment [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComputerEquipmentMember" xlink:to="lab_us-gaap_ComputerEquipmentMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquipmentMember" xlink:label="loc_us-gaap_EquipmentMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EquipmentMember" xml:lang="en-US">Equipment [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EquipmentMember" xml:lang="en-US">Medical Equipment [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquipmentMember" xlink:to="lab_us-gaap_EquipmentMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FurnitureAndFixturesMember" xml:lang="en-US">Furniture and Fixtures [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FurnitureAndFixturesMember" xml:lang="en-US">Furniture [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FurnitureAndFixturesMember" xlink:to="lab_us-gaap_FurnitureAndFixturesMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xml:lang="en-US">Software and Software Development Costs [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xml:lang="en-US">Software and Software Development Costs [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:to="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_RangeAxis" xml:lang="en-US">Range [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_RangeAxis" xml:lang="en-US">Range [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeAxis" xlink:to="lab_srt_RangeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_RangeMember" xml:lang="en-US">Range [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_RangeMember" xml:lang="en-US">Range [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeMember" xlink:to="lab_srt_RangeMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_MaximumMember" xml:lang="en-US">Maximum [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_MaximumMember" xml:lang="en-US">Maximum [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MaximumMember" xlink:to="lab_srt_MaximumMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_MinimumMember" xml:lang="en-US">Minimum [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_MinimumMember" xml:lang="en-US">Minimum [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MinimumMember" xlink:to="lab_srt_MinimumMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xml:lang="en-US">Investment, Name [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xml:lang="en-US">Investment, Name [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="loc_srt_EquityMethodInvesteeNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_EquityMethodInvesteeNameDomain" xml:lang="en-US">Investment, Name [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_EquityMethodInvesteeNameDomain" xml:lang="en-US">Investment, Name [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_EquityMethodInvesteeNameDomain" xlink:to="lab_srt_EquityMethodInvesteeNameDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_UnnamedCorporateJointVentureOneMember" xlink:label="loc_md_UnnamedCorporateJointVentureOneMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_UnnamedCorporateJointVentureOneMember" xml:lang="en-US">Unnamed Corporate Joint Venture One [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_UnnamedCorporateJointVentureOneMember" xml:lang="en-US">Unnamed Corporate Joint Venture One [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_UnnamedCorporateJointVentureOneMember" xlink:to="lab_md_UnnamedCorporateJointVentureOneMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_UnnamedCorporateJointVentureOneMember" xml:lang="en-US">Unnamed Corporate Joint Venture [Member]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_UnnamedCorporateJointVentureTwoMember" xlink:label="loc_md_UnnamedCorporateJointVentureTwoMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_UnnamedCorporateJointVentureTwoMember" xml:lang="en-US">Unnamed Corporate Joint Venture Two [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_UnnamedCorporateJointVentureTwoMember" xml:lang="en-US">Unnamed Corporate Joint Venture Two [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_UnnamedCorporateJointVentureTwoMember" xlink:to="lab_md_UnnamedCorporateJointVentureTwoMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_SummaryOfSignificantAccountingPoliciesLineItems" xlink:label="loc_md_SummaryOfSignificantAccountingPoliciesLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesLineItems" xml:lang="en-US">Summary Of Significant Accounting Policies [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesLineItems" xml:lang="en-US">Summary Of Significant Accounting Policies [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_SummaryOfSignificantAccountingPoliciesLineItems" xlink:to="lab_md_SummaryOfSignificantAccountingPoliciesLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_SummaryOfSignificantAccountingPoliciesLineItems" xml:lang="en-US">Summary of significant accounting policies.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" xlink:label="loc_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" xml:lang="en-US">Business Combination Contingent Consideration Arrangements Time Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" xml:lang="en-US">Additional amounts to be paid in cash or common stock based on achievement of performance measures within period, maximum years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" xlink:to="lab_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_BusinessCombinationContingentConsiderationArrangementsTimePeriod" xml:lang="en-US">Business combination, contingent consideration arrangements, time period.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CashAndCashEquivalentsMaturityDescription" xlink:label="loc_md_CashAndCashEquivalentsMaturityDescription" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CashAndCashEquivalentsMaturityDescription" xml:lang="en-US">Cash And Cash Equivalents Maturity Description</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CashAndCashEquivalentsMaturityDescription" xml:lang="en-US">Cash and cash equivalents maturity description</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CashAndCashEquivalentsMaturityDescription" xlink:to="lab_md_CashAndCashEquivalentsMaturityDescription" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CashAndCashEquivalentsMaturityDescription" xml:lang="en-US">Cash and cash equivalents maturity description.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xml:lang="en-US">Concentration Risk, Percentage</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xml:lang="en-US">Percentage of net accounts receivable</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xml:lang="en-US">Net revenue in percentage</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskPercentage1" xlink:to="lab_us-gaap_ConcentrationRiskPercentage1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EquityMethodInvestmentOwnershipPercentage" xml:lang="en-US">Equity Method Investment, Ownership Percentage</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EquityMethodInvestmentOwnershipPercentage" xml:lang="en-US">Equity method ownership percentage in joint venture</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_EquityMethodInvestmentOwnershipPercentage" xml:lang="en-US">Sale of equity method investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:to="lab_us-gaap_EquityMethodInvestmentOwnershipPercentage" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xml:lang="en-US">Finite-Lived Intangible Asset, Useful Life</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xml:lang="en-US">Intangible assets finite lives</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xml:lang="en-US">Property, Plant and Equipment, Useful Life</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xml:lang="en-US">Property and equipment estimated useful lives, years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ShortTermInvestmentMaturityPeriod" xlink:label="loc_md_ShortTermInvestmentMaturityPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ShortTermInvestmentMaturityPeriod" xml:lang="en-US">Short Term Investment Maturity Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ShortTermInvestmentMaturityPeriod" xml:lang="en-US">Short-Term investments maturity period, in years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ShortTermInvestmentMaturityPeriod" xlink:to="lab_md_ShortTermInvestmentMaturityPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ShortTermInvestmentMaturityPeriod" xml:lang="en-US">Short term investment maturity period.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" xml:lang="en-US">Proceeds from Divestiture of Businesses, Net of Cash Divested</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" xml:lang="en-US">Cash Payments Received On Divestiture Of MedData</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" xlink:to="lab_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" xlink:label="loc_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" xml:lang="en-US">Divestiture Of Businesses Contingent Consideration Receivable in Equity Shares</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" xml:lang="en-US">Equity consideration in the parent company of Buyer</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" xlink:to="lab_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DivestitureOfBusinessesContingentConsiderationReceivableInEquityShares" xml:lang="en-US">Divestiture Of Businesses, Contingent Consideration Receivable in Equity Shares.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xml:lang="en-US">Goodwill, Impaired, Accumulated Impairment Loss</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xml:lang="en-US">Accumulated Non cash impairment charge of goodwill</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:to="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis" xml:lang="en-US">Segments [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis" xml:lang="en-US">Segments [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis" xlink:to="lab_us-gaap_StatementBusinessSegmentsAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SegmentDomain" xml:lang="en-US">Segments [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SegmentDomain" xml:lang="en-US">Segments [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentDomain" xlink:to="lab_us-gaap_SegmentDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_RegulatoryAssetsAbstract" xlink:label="loc_md_RegulatoryAssetsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_RegulatoryAssetsAbstract" xml:lang="en-US">Regulatory Assets [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_RegulatoryAssetsAbstract" xlink:to="lab_md_RegulatoryAssetsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_RegulatoryAssetsAbstract" xml:lang="en-US">Regulatory Assets [Abstract]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xml:lang="en-US">Schedule of Segment Reporting Information, by Segment [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xml:lang="en-US">Schedule of Segment Reporting Information, by Segment [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_SalesAndRevenueServicesNetMember" xlink:label="loc_md_SalesAndRevenueServicesNetMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_SalesAndRevenueServicesNetMember" xml:lang="en-US">Sales And Revenue Services Net [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_SalesAndRevenueServicesNetMember" xml:lang="en-US">Sales Revenue, Services, Net [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_SalesAndRevenueServicesNetMember" xlink:to="lab_md_SalesAndRevenueServicesNetMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProductConcentrationRiskMember" xlink:label="loc_us-gaap_ProductConcentrationRiskMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProductConcentrationRiskMember" xml:lang="en-US">Product Concentration Risk [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProductConcentrationRiskMember" xml:lang="en-US">Product Concentration Risk [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProductConcentrationRiskMember" xlink:to="lab_us-gaap_ProductConcentrationRiskMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_ProductOrServiceAxis" xml:lang="en-US">Product and Service [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_ProductOrServiceAxis" xml:lang="en-US">Product and Service [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductOrServiceAxis" xlink:to="lab_srt_ProductOrServiceAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_ProductsAndServicesDomain" xml:lang="en-US">Product and Service [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_ProductsAndServicesDomain" xml:lang="en-US">Product and Service [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductsAndServicesDomain" xlink:to="lab_srt_ProductsAndServicesDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NeonatologyAndOtherPediatricSubspecialtiesMember" xlink:label="loc_md_NeonatologyAndOtherPediatricSubspecialtiesMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NeonatologyAndOtherPediatricSubspecialtiesMember" xml:lang="en-US">Neonatology And Other Pediatric Subspecialties [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_NeonatologyAndOtherPediatricSubspecialtiesMember" xml:lang="en-US">Neonatology and Other Pediatric Subspecialties [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NeonatologyAndOtherPediatricSubspecialtiesMember" xlink:to="lab_md_NeonatologyAndOtherPediatricSubspecialtiesMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NeonatologyAndOtherPediatricSubspecialtiesMember" xml:lang="en-US">Neonatology and other pediatric subspecialties.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_RadiologyAndTeleradiologyMember" xlink:label="loc_md_RadiologyAndTeleradiologyMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_RadiologyAndTeleradiologyMember" xml:lang="en-US">Radiology And Teleradiology [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_RadiologyAndTeleradiologyMember" xml:lang="en-US">Radiology And Teleradiology [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_RadiologyAndTeleradiologyMember" xlink:to="lab_md_RadiologyAndTeleradiologyMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_RadiologyAndTeleradiologyMember" xml:lang="en-US">Radiology and teleradiology.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AnesthesiologyAndRelatedMember" xlink:label="loc_md_AnesthesiologyAndRelatedMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AnesthesiologyAndRelatedMember" xml:lang="en-US">Anesthesiology And Related [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AnesthesiologyAndRelatedMember" xml:lang="en-US">Anesthesiology And Related [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AnesthesiologyAndRelatedMember" xlink:to="lab_md_AnesthesiologyAndRelatedMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AnesthesiologyAndRelatedMember" xml:lang="en-US">Anesthesiology And Related Member.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SegmentReportingInformationLineItems" xml:lang="en-US">Segment Reporting Information [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SegmentReportingInformationLineItems" xml:lang="en-US">Segment Reporting Information [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems" xlink:to="lab_us-gaap_SegmentReportingInformationLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueDisclosuresAbstract" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueDisclosuresAbstract" xml:lang="en-US">Fair Value Disclosures [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract" xlink:to="lab_us-gaap_FairValueDisclosuresAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StatementClassOfStockAxis" xml:lang="en-US">Class of Stock [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="lab_us-gaap_StatementClassOfStockAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ClassOfStockDomain" xml:lang="en-US">Class of Stock [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="lab_us-gaap_ClassOfStockDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsFairValueDisclosureAbstract" xml:lang="en-US">Assets, Fair Value Disclosure [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AssetsFairValueDisclosureAbstract" xml:lang="en-US">Assets:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract" xlink:to="lab_us-gaap_AssetsFairValueDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_MoneyMarketFundsFairValueDisclosure" xlink:label="loc_md_MoneyMarketFundsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_MoneyMarketFundsFairValueDisclosure" xml:lang="en-US">Money Market Funds Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_MoneyMarketFundsFairValueDisclosure" xml:lang="en-US">Money market funds</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_MoneyMarketFundsFairValueDisclosure" xlink:to="lab_md_MoneyMarketFundsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_MoneyMarketFundsFairValueDisclosure" xml:lang="en-US">Fair value of money market funds.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentsFairValueDisclosure" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentsFairValueDisclosure" xml:lang="en-US">Investments, Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_InvestmentsFairValueDisclosure" xml:lang="en-US">Short-term investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentsFairValueDisclosure" xlink:to="lab_us-gaap_InvestmentsFairValueDisclosure" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CompanyOwnedLifeInsuranceFairValueDisclosure" xlink:label="loc_md_CompanyOwnedLifeInsuranceFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CompanyOwnedLifeInsuranceFairValueDisclosure" xml:lang="en-US">Company Owned Life Insurance Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_CompanyOwnedLifeInsuranceFairValueDisclosure" xml:lang="en-US">Company-owned life insurance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CompanyOwnedLifeInsuranceFairValueDisclosure" xlink:to="lab_md_CompanyOwnedLifeInsuranceFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CompanyOwnedLifeInsuranceFairValueDisclosure" xml:lang="en-US">Fair value of company owned life insurance.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_MutualFundsFairValueDisclosure" xlink:label="loc_md_MutualFundsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_MutualFundsFairValueDisclosure" xml:lang="en-US">Mutual Funds Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_MutualFundsFairValueDisclosure" xml:lang="en-US">Mutual funds</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_MutualFundsFairValueDisclosure" xlink:to="lab_md_MutualFundsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_MutualFundsFairValueDisclosure" xml:lang="en-US">Mutual funds fair value disclosure.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesFairValueDisclosureAbstract" xml:lang="en-US">Liabilities, Fair Value Disclosure [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LiabilitiesFairValueDisclosureAbstract" xml:lang="en-US">Liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:to="lab_us-gaap_LiabilitiesFairValueDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" xlink:label="loc_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" xml:lang="en-US">Business Combination Contingent Consideration Liability Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" xml:lang="en-US">Contingent consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" xlink:to="lab_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_BusinessCombinationContingentConsiderationLiabilityFairValueDisclosure" xml:lang="en-US">Fair value Of contingent consideration liability.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis" xml:lang="en-US">Fair Value Hierarchy and NAV [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis" xml:lang="en-US">Fair Value Hierarchy and NAV [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xml:lang="en-US">Fair Value Hierarchy and NAV [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xml:lang="en-US">Fair Value Hierarchy and NAV [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueInputsLevel1Member" xml:lang="en-US">Fair Value, Inputs, Level 1 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueInputsLevel1Member" xlink:to="lab_us-gaap_FairValueInputsLevel1Member" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueInputsLevel2Member" xml:lang="en-US">Fair Value, Inputs, Level 2 [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FairValueInputsLevel2Member" xml:lang="en-US">Level 2 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueInputsLevel2Member" xlink:to="lab_us-gaap_FairValueInputsLevel2Member" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueInputsLevel3Member" xml:lang="en-US">Fair Value, Inputs, Level 3 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueInputsLevel3Member" xlink:to="lab_us-gaap_FairValueInputsLevel3Member" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueByMeasurementFrequencyAxis" xml:lang="en-US">Measurement Frequency [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="lab_us-gaap_FairValueByMeasurementFrequencyAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueMeasurementFrequencyDomain" xml:lang="en-US">Fair Value, Measurement Frequency [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="lab_us-gaap_FairValueMeasurementFrequencyDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueMeasurementsRecurringMember" xml:lang="en-US">Fair Value, Measurements, Recurring [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:to="lab_us-gaap_FairValueMeasurementsRecurringMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermInvestments" xlink:label="loc_us-gaap_ShortTermInvestments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShortTermInvestments" xml:lang="en-US">Short-term Investments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ShortTermInvestments" xml:lang="en-US">Carrying Amount, Short-term investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShortTermInvestments" xlink:to="lab_us-gaap_ShortTermInvestments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermInvestments" xlink:label="loc_us-gaap_LongTermInvestments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LongTermInvestments" xml:lang="en-US">Carrying Amount, Long-term Investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermInvestments" xlink:to="lab_us-gaap_LongTermInvestments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAbstract" xlink:label="loc_us-gaap_LiabilitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesAbstract" xml:lang="en-US">Liabilities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LiabilitiesAbstract" xml:lang="en-US">Liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="lab_us-gaap_LiabilitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayable" xlink:label="loc_us-gaap_NotesPayable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NotesPayable" xml:lang="en-US">Notes Payable</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_NotesPayable" xml:lang="en-US">Notes Payable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NotesPayable" xlink:to="lab_us-gaap_NotesPayable" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ShortTermInvestmentsFairValueDisclosure" xlink:label="loc_md_ShortTermInvestmentsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ShortTermInvestmentsFairValueDisclosure" xml:lang="en-US">Short Term Investments Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_ShortTermInvestmentsFairValueDisclosure" xml:lang="en-US">Fair Value, Short-term investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ShortTermInvestmentsFairValueDisclosure" xlink:to="lab_md_ShortTermInvestmentsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ShortTermInvestmentsFairValueDisclosure" xml:lang="en-US">Fair value of short term investsments.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_LongTermInvestmentsFairValueDisclosure" xlink:label="loc_md_LongTermInvestmentsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_LongTermInvestmentsFairValueDisclosure" xml:lang="en-US">Long Term Investments Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_LongTermInvestmentsFairValueDisclosure" xml:lang="en-US">Fair Value, Long-term investments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_LongTermInvestmentsFairValueDisclosure" xlink:to="lab_md_LongTermInvestmentsFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_LongTermInvestmentsFairValueDisclosure" xml:lang="en-US">Fair value of long term investsments.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NotesPayableFairValueDisclosure" xlink:label="loc_us-gaap_NotesPayableFairValueDisclosure" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_NotesPayableFairValueDisclosure" xml:lang="en-US">Notes Payable, Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_NotesPayableFairValueDisclosure" xml:lang="en-US">Notes Payable Fair Value Disclosure</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_NotesPayableFairValueDisclosure" xml:lang="en-US">Estimated fair value</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NotesPayableFairValueDisclosure" xlink:to="lab_us-gaap_NotesPayableFairValueDisclosure" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentAxis" xml:lang="en-US">Debt Instrument [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentAxis" xml:lang="en-US">Debt Instrument [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentAxis" xlink:to="lab_us-gaap_DebtInstrumentAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xml:lang="en-US">Debt Instrument, Name [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xml:lang="en-US">Debt Instrument, Name [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentNameDomain" xlink:to="lab_us-gaap_DebtInstrumentNameDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_TwoThousandTwentyThreeMember" xlink:label="loc_md_TwoThousandTwentyThreeMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_TwoThousandTwentyThreeMember" xml:lang="en-US">Two Thousand Twenty Three [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_TwoThousandTwentyThreeMember" xml:lang="en-US">2023 Notes [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_TwoThousandTwentyThreeMember" xlink:to="lab_md_TwoThousandTwentyThreeMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_TwoThousandTwentySevenMember" xlink:label="loc_md_TwoThousandTwentySevenMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_TwoThousandTwentySevenMember" xml:lang="en-US">Two Thousand Twenty Seven [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_TwoThousandTwentySevenMember" xml:lang="en-US">2027 Notes [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_TwoThousandTwentySevenMember" xlink:to="lab_md_TwoThousandTwentySevenMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentsAbstract" xlink:label="loc_us-gaap_InvestmentsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentsAbstract" xml:lang="en-US">Investments [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentsAbstract" xlink:to="lab_us-gaap_InvestmentsAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" xml:lang="en-US">Debt Securities, Held-to-maturity [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" xml:lang="en-US">Debt Securities, Held-to-maturity [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" xlink:to="lab_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentTypeAxis" xml:lang="en-US">Investment Type [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InvestmentTypeAxis" xml:lang="en-US">Investment Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTypeAxis" xlink:to="lab_us-gaap_InvestmentTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InvestmentTypeCategorizationMember" xml:lang="en-US">Investments [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_InvestmentTypeCategorizationMember" xml:lang="en-US">Corporate Securities [member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember" xlink:to="lab_us-gaap_InvestmentTypeCategorizationMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CertificatesOfDepositMember" xml:lang="en-US">Certificates of Deposit [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CertificatesOfDepositMember" xml:lang="en-US">Certificates of Deposit [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CertificatesOfDepositMember" xlink:to="lab_us-gaap_CertificatesOfDepositMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xml:lang="en-US">US Government-sponsored Enterprises Debt Securities [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xml:lang="en-US">Federal Home Loan Securities [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" xlink:to="lab_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_USStatesAndPoliticalSubdivisionsMember" xml:lang="en-US">US States and Political Subdivisions Debt Securities [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_USStatesAndPoliticalSubdivisionsMember" xml:lang="en-US">Municipal Debt Securities [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember" xlink:to="lab_us-gaap_USStatesAndPoliticalSubdivisionsMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllOtherCorporateBondsMember" xlink:label="loc_us-gaap_AllOtherCorporateBondsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AllOtherCorporateBondsMember" xml:lang="en-US">Other Corporate Bonds [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AllOtherCorporateBondsMember" xml:lang="en-US">Corporate Securities [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllOtherCorporateBondsMember" xlink:to="lab_us-gaap_AllOtherCorporateBondsMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xml:lang="en-US">Debt Securities, Available-for-sale [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xml:lang="en-US">Schedule of Avaliable-For-Sale Securities [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:to="lab_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesCurrent" xml:lang="en-US">Available-for-sale Securities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesCurrent" xml:lang="en-US">Short-Term</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesCurrent" xlink:to="lab_us-gaap_AvailableForSaleSecuritiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AvailableForSaleSecuritiesNoncurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesNoncurrent" xml:lang="en-US">Available-for-sale Securities, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AvailableForSaleSecuritiesNoncurrent" xml:lang="en-US">Long-Term</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent" xlink:to="lab_us-gaap_AvailableForSaleSecuritiesNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="loc_us-gaap_ReceivablesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ReceivablesAbstract" xml:lang="en-US">Receivables [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReceivablesAbstract" xlink:to="lab_us-gaap_ReceivablesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsReceivableGrossCurrent" xml:lang="en-US">Accounts Receivable, Gross, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccountsReceivableGrossCurrent" xml:lang="en-US">Gross accounts receivable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableGrossCurrent" xlink:to="lab_us-gaap_AccountsReceivableGrossCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xml:lang="en-US">Allowance for Doubtful Accounts Receivable, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xml:lang="en-US">Allowance for contractual adjustments and uncollectibles</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:to="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract" xml:lang="en-US">Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract" xlink:to="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xml:lang="en-US">Schedule of Accounts, Notes, Loans and Financing Receivable [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xml:lang="en-US">Schedule of Accounts, Notes, Loans and Financing Receivable [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="lab_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCarePatientServiceMember" xlink:label="loc_us-gaap_HealthCarePatientServiceMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCarePatientServiceMember" xml:lang="en-US">Health Care, Patient Service [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_HealthCarePatientServiceMember" xml:lang="en-US">Net patient service revenue [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCarePatientServiceMember" xlink:to="lab_us-gaap_HealthCarePatientServiceMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_HospitalsContractsMember" xlink:label="loc_md_HospitalsContractsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_HospitalsContractsMember" xml:lang="en-US">Hospitals Contracts [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_HospitalsContractsMember" xml:lang="en-US">Hospital contract administrative fees [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_HospitalsContractsMember" xlink:to="lab_md_HospitalsContractsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_HospitalsContractsMember" xml:lang="en-US">Hospitals Contracts [Member]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProductAndServiceOtherMember" xlink:label="loc_us-gaap_ProductAndServiceOtherMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProductAndServiceOtherMember" xml:lang="en-US">Product and Service, Other [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ProductAndServiceOtherMember" xml:lang="en-US">Other revenue [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProductAndServiceOtherMember" xlink:to="lab_us-gaap_ProductAndServiceOtherMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ScheduleOfFinancingReceivablesLineItems" xlink:label="loc_md_ScheduleOfFinancingReceivablesLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ScheduleOfFinancingReceivablesLineItems" xml:lang="en-US">Schedule Of Financing Receivables [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ScheduleOfFinancingReceivablesLineItems" xml:lang="en-US">Schedule Of Financing Receivables [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ScheduleOfFinancingReceivablesLineItems" xlink:to="lab_md_ScheduleOfFinancingReceivablesLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ScheduleOfFinancingReceivablesLineItems" xml:lang="en-US">Schedule of financing receivables.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueAbstract" xlink:label="loc_us-gaap_DisaggregationOfRevenueAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisaggregationOfRevenueAbstract" xml:lang="en-US">Disaggregation of Revenue [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisaggregationOfRevenueAbstract" xml:lang="en-US">Disaggregation of Revenue [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueAbstract" xlink:to="lab_us-gaap_DisaggregationOfRevenueAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCareOrganizationRevenueAndExpenseAbstract" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueAndExpenseAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCareOrganizationRevenueAndExpenseAbstract" xml:lang="en-US">Health Care Organization Revenue and Expense [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueAndExpenseAbstract" xlink:to="lab_us-gaap_HealthCareOrganizationRevenueAndExpenseAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" xlink:label="loc_us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" xml:lang="en-US">Schedule of Revenue Sources, Health Care Organization [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" xml:lang="en-US">Schedule of Revenue Sources, Health Care Organization [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" xlink:to="lab_us-gaap_ScheduleOfRevenueSourcesHealthCareOrganizationTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" xlink:label="loc_us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" xml:lang="en-US">Health Care Organization, Receivable and Revenue Disclosures [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" xml:lang="en-US">Health Care Organization, Receivable and Revenue Disclosures [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" xlink:to="lab_us-gaap_HealthCareOrganizationReceivableAndRevenueDisclosuresLineItems" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" xlink:label="loc_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" xml:lang="en-US">Percentage Of Net Patient Service Revenue By Type Of Payor</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" xml:lang="en-US">Percentage of net patient service revenue</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" xlink:to="lab_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PercentageOfNetPatientServiceRevenueByTypeOfPayor" xml:lang="en-US">Percentage of net patient service revenue by type payor.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xml:lang="en-US">Health Care Organization, Revenue Sources [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xml:lang="en-US">Health Care Organization, Revenue Sources [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:to="lab_us-gaap_HealthCareOrganizationRevenueSourcesAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xml:lang="en-US">Health Care Organization, Revenue Sources [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xml:lang="en-US">Health Care Organization, Revenue Sources [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:to="lab_us-gaap_HealthCareOrganizationRevenueSourcesDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ContractedManagedCareMember" xlink:label="loc_md_ContractedManagedCareMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ContractedManagedCareMember" xml:lang="en-US">Contracted Managed Care [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ContractedManagedCareMember" xml:lang="en-US">Contracted Managed Care [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ContractedManagedCareMember" xlink:to="lab_md_ContractedManagedCareMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ContractedManagedCareMember" xml:lang="en-US">Contracted Managed Care [Member]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GovernmentMember" xlink:label="loc_us-gaap_GovernmentMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GovernmentMember" xml:lang="en-US">Government [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GovernmentMember" xml:lang="en-US">Government [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GovernmentMember" xlink:to="lab_us-gaap_GovernmentMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SelfPayMember" xlink:label="loc_us-gaap_SelfPayMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SelfPayMember" xml:lang="en-US">Self-Pay [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SelfPayMember" xml:lang="en-US">Private-Pay Patients [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SelfPayMember" xlink:to="lab_us-gaap_SelfPayMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ThirdPartyPayorMember" xlink:label="loc_us-gaap_ThirdPartyPayorMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ThirdPartyPayorMember" xml:lang="en-US">Third-Party Payor [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ThirdPartyPayorMember" xml:lang="en-US">Other Third-Parties [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ThirdPartyPayorMember" xlink:to="lab_us-gaap_ThirdPartyPayorMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xml:lang="en-US">Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xml:lang="en-US">Accumulated depreciation</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:to="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BuildingsAndImprovementsGross" xlink:label="loc_us-gaap_BuildingsAndImprovementsGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BuildingsAndImprovementsGross" xml:lang="en-US">Buildings and Improvements, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_BuildingsAndImprovementsGross" xml:lang="en-US">Building</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BuildingsAndImprovementsGross" xlink:to="lab_us-gaap_BuildingsAndImprovementsGross" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FixturesAndEquipmentGross" xlink:label="loc_us-gaap_FixturesAndEquipmentGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FixturesAndEquipmentGross" xml:lang="en-US">Fixtures and Equipment, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FixturesAndEquipmentGross" xml:lang="en-US">Equipment and other</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FixturesAndEquipmentGross" xlink:to="lab_us-gaap_FixturesAndEquipmentGross" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Land" xlink:label="loc_us-gaap_Land" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_Land" xml:lang="en-US">Land</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_Land" xml:lang="en-US">Land</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Land" xlink:to="lab_us-gaap_Land" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xml:lang="en-US">Property, Plant and Equipment, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xml:lang="en-US">Property and equipment, gross</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentGross" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" xlink:label="loc_md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" xml:lang="en-US">Property Plant And Equipment Capitalized Interest Costs [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" xlink:to="lab_md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PropertyPlantAndEquipmentCapitalizedInterestCostsAbstract" xml:lang="en-US">Property Plant And Equipment Capitalized Interest Costs [Abstract]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xml:lang="en-US">Property, Plant and Equipment [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xml:lang="en-US">Property, Plant and Equipment [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xml:lang="en-US">Property, Plant and Equipment [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xml:lang="en-US">Property, Plant and Equipment [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_Depreciation" xml:lang="en-US">Depreciation</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_Depreciation" xml:lang="en-US">Recorded depreciation expense</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Depreciation" xlink:to="lab_us-gaap_Depreciation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessAcquisitionLineItems" xml:lang="en-US">Business Acquisition [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems" xlink:to="lab_us-gaap_BusinessAcquisitionLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferred1" xml:lang="en-US">Business Combination, Consideration Transferred</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferred1" xml:lang="en-US">Total business acquisition consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:to="lab_us-gaap_BusinessCombinationConsiderationTransferred1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod" xml:lang="en-US">Goodwill, Acquired During Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod" xml:lang="en-US">Goodwill</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAcquiredDuringPeriod" xlink:to="lab_us-gaap_GoodwillAcquiredDuringPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xml:lang="en-US">Other intangible assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsForPreviousAcquisition" xlink:label="loc_us-gaap_PaymentsForPreviousAcquisition" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsForPreviousAcquisition" xml:lang="en-US">Payments for Previous Acquisition</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_PaymentsForPreviousAcquisition" xml:lang="en-US">Contingent consideration payments related to prior-period acquisitions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForPreviousAcquisition" xlink:to="lab_us-gaap_PaymentsForPreviousAcquisition" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xml:lang="en-US">Business Acquisition, Goodwill, Expected Tax Deductible Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xml:lang="en-US">Goodwill deductible for tax purposes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:to="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" xlink:label="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" xml:lang="en-US">Assets Held-for-sale, Not Part of Disposal Group</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" xml:lang="en-US">Assets held for sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" xlink:to="lab_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroup" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NumberOfPhysicianGroupPracticesAcquired" xlink:label="loc_md_NumberOfPhysicianGroupPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NumberOfPhysicianGroupPracticesAcquired" xml:lang="en-US">Number Of Physician Group Practices Acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NumberOfPhysicianGroupPracticesAcquired" xlink:to="lab_md_NumberOfPhysicianGroupPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NumberOfPhysicianGroupPracticesAcquired" xml:lang="en-US">Number of physician group practices acquired.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NumberOfNeonatologyPracticesAcquired" xlink:label="loc_md_NumberOfNeonatologyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NumberOfNeonatologyPracticesAcquired" xml:lang="en-US">Number Of Neonatology Practices Acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NumberOfNeonatologyPracticesAcquired" xlink:to="lab_md_NumberOfNeonatologyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NumberOfNeonatologyPracticesAcquired" xml:lang="en-US">Number of neonatology practices acquired.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NumberOfPediatricSubspecialtyPracticesAcquired" xlink:label="loc_md_NumberOfPediatricSubspecialtyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NumberOfPediatricSubspecialtyPracticesAcquired" xml:lang="en-US">Number Of Pediatric Subspecialty Practices Acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NumberOfPediatricSubspecialtyPracticesAcquired" xlink:to="lab_md_NumberOfPediatricSubspecialtyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NumberOfPediatricSubspecialtyPracticesAcquired" xml:lang="en-US">Number of other pediatric subspecialty practices acquired.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NumberOfRadiologyPracticesAcquired" xlink:label="loc_md_NumberOfRadiologyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NumberOfRadiologyPracticesAcquired" xml:lang="en-US">Number Of Radiology Practices Acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NumberOfRadiologyPracticesAcquired" xlink:to="lab_md_NumberOfRadiologyPracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NumberOfRadiologyPracticesAcquired" xml:lang="en-US">Number of radiology practices acquired.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NumberOfMaternalfetalMedicinePracticesAcquired" xlink:label="loc_md_NumberOfMaternalfetalMedicinePracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NumberOfMaternalfetalMedicinePracticesAcquired" xml:lang="en-US">Number Of Maternal-fetal Medicine Practices Acquired</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NumberOfMaternalfetalMedicinePracticesAcquired" xlink:to="lab_md_NumberOfMaternalfetalMedicinePracticesAcquired" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NumberOfMaternalfetalMedicinePracticesAcquired" xml:lang="en-US">Number of maternal-fetal medicine practices acquired.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xml:lang="en-US">Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xml:lang="en-US">Change in the fair value of a contingent consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccruedPurchaseConsideration" xlink:label="loc_md_AccruedPurchaseConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccruedPurchaseConsideration" xml:lang="en-US">Accrued Purchase Consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccruedPurchaseConsideration" xlink:to="lab_md_AccruedPurchaseConsideration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccruedPurchaseConsideration" xml:lang="en-US">Accrued purchase consideration.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xml:lang="en-US">Decrease in current assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherLiabilities" xlink:label="loc_us-gaap_OtherLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherLiabilities" xml:lang="en-US">Other Liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilities" xlink:to="lab_us-gaap_OtherLiabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" xml:lang="en-US">Goodwill, Purchase Accounting Adjustments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" xml:lang="en-US">Net increase in goodwill resulting from finalization of tax acquisition accounting</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:to="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesGross" xml:lang="en-US">Payments to Acquire Businesses, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesGross" xml:lang="en-US">Additional cash consideration related to a working capital true up</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireBusinessesGross" xlink:to="lab_us-gaap_PaymentsToAcquireBusinessesGross" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" xlink:label="loc_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" xml:lang="en-US">Payment For Purchase Consideration Related To Prior Period Acquisitions</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" xml:lang="en-US">Purchase consideration payments related to prior-period acquisitions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" xlink:to="lab_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PaymentForPurchaseConsiderationRelatedToPriorPeriodAcquisitions" xml:lang="en-US">Payment For Purchase Consideration Related To Prior Period Acquisitions</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xml:lang="en-US">Decrease in liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" xml:lang="en-US">Decrease in noncurrent assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xml:lang="en-US">Fixed assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessAcquisitionAxis" xml:lang="en-US">Business Acquisition [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAxis" xlink:to="lab_us-gaap_BusinessAcquisitionAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_BusinessAcquisitionAcquireeDomain" xml:lang="en-US">Business Acquisition, Acquiree [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="lab_us-gaap_BusinessAcquisitionAcquireeDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PhysicianGroupMember" xlink:label="loc_md_PhysicianGroupMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PhysicianGroupMember" xml:lang="en-US">Physician Group [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PhysicianGroupMember" xml:lang="en-US">Physician Group [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PhysicianGroupMember" xlink:to="lab_md_PhysicianGroupMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PhysicianGroupMember" xml:lang="en-US">Physician group.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PriorPeriodAcquisitionsMember" xlink:label="loc_md_PriorPeriodAcquisitionsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PriorPeriodAcquisitionsMember" xml:lang="en-US">Prior Period Acquisitions [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PriorPeriodAcquisitionsMember" xml:lang="en-US">Prior Period Acquisitions [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PriorPeriodAcquisitionsMember" xlink:to="lab_md_PriorPeriodAcquisitionsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PriorPeriodAcquisitionsMember" xml:lang="en-US">Prior-period acquisitions.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xml:lang="en-US">Schedule of Business Acquisitions, by Acquisition [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xml:lang="en-US">Schedule of Business Acquisitions, by Acquisition [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xml:lang="en-US">Finite-Lived Intangible Assets by Major Class [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xml:lang="en-US">Finite-Lived Intangible Assets by Major Class [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xml:lang="en-US">Finite-Lived Intangible Assets, Major Class Name [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xml:lang="en-US">Finite-Lived Intangible Assets, Major Class Name [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PhysicianAndHospitalAgreementsMember" xlink:label="loc_md_PhysicianAndHospitalAgreementsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PhysicianAndHospitalAgreementsMember" xml:lang="en-US">Physician And Hospital Agreements [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PhysicianAndHospitalAgreementsMember" xml:lang="en-US">Physician And Hospital Agreements [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PhysicianAndHospitalAgreementsMember" xlink:to="lab_md_PhysicianAndHospitalAgreementsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PhysicianAndHospitalAgreementsMember" xml:lang="en-US">Physician And Hospital Agreements [Member]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_GoodwillAndOtherIntangibleAssetsLineItems" xlink:label="loc_md_GoodwillAndOtherIntangibleAssetsLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_GoodwillAndOtherIntangibleAssetsLineItems" xml:lang="en-US">Goodwill And Other Intangible Assets [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_GoodwillAndOtherIntangibleAssetsLineItems" xml:lang="en-US">Goodwill And Other Intangible Assets [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_GoodwillAndOtherIntangibleAssetsLineItems" xlink:to="lab_md_GoodwillAndOtherIntangibleAssetsLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_GoodwillAndOtherIntangibleAssetsLineItems" xml:lang="en-US">Goodwill And Other Intangible Assets [Line Items]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xml:lang="en-US">Acquired Finite-lived Intangible Assets, Weighted Average Useful Life</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xml:lang="en-US">Weighted average amortization period</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:to="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets" xml:lang="en-US">Amortization of Intangible Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets" xml:lang="en-US">Amortization expense for intangible assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AmortizationOfIntangibleAssets" xlink:to="lab_us-gaap_AmortizationOfIntangibleAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" xml:lang="en-US">Finite-lived Intangible Assets Acquired</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" xml:lang="en-US">Intangible assets related to acquisitions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:to="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_GoodwillRecognitionOfDeferredTaxAsset" xlink:label="loc_md_GoodwillRecognitionOfDeferredTaxAsset" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_GoodwillRecognitionOfDeferredTaxAsset" xml:lang="en-US">Goodwill Recognition Of Deferred Tax Asset</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_GoodwillRecognitionOfDeferredTaxAsset" xml:lang="en-US">Goodwill recognition of deferred tax asset</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_GoodwillRecognitionOfDeferredTaxAsset" xlink:to="lab_md_GoodwillRecognitionOfDeferredTaxAsset" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_GoodwillRecognitionOfDeferredTaxAsset" xml:lang="en-US">Goodwill recognition of deferred tax asset.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_GoodwillIncrementalImpairmentCharges" xlink:label="loc_md_GoodwillIncrementalImpairmentCharges" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_GoodwillIncrementalImpairmentCharges" xml:lang="en-US">Goodwill Incremental Impairment Charges</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_GoodwillIncrementalImpairmentCharges" xml:lang="en-US">Goodwill incremental impairment charges</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_GoodwillIncrementalImpairmentCharges" xlink:to="lab_md_GoodwillIncrementalImpairmentCharges" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_GoodwillIncrementalImpairmentCharges" xml:lang="en-US">Goodwill incremental impairment charges.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AnaesthesiologyReportingUnitMember" xlink:label="loc_md_AnaesthesiologyReportingUnitMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AnaesthesiologyReportingUnitMember" xml:lang="en-US">Anaesthesiology Reporting Unit [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_AnaesthesiologyReportingUnitMember" xml:lang="en-US">Anaesthesiology Reporting Unit [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AnaesthesiologyReportingUnitMember" xlink:to="lab_md_AnaesthesiologyReportingUnitMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AnaesthesiologyReportingUnitMember" xml:lang="en-US">Anaesthesiology Reporting Unit</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xml:lang="en-US">Schedule of Finite-Lived Intangible Assets [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xml:lang="en-US">Schedule of Finite-Lived Intangible Assets [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CustomerRelationshipsMember" xml:lang="en-US">Customer Relationships [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CustomerRelationshipsMember" xml:lang="en-US">Customer Relationships [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CustomerRelationshipsMember" xlink:to="lab_us-gaap_CustomerRelationshipsMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_PatentedAndOtherTechnologyMember" xlink:label="loc_md_PatentedAndOtherTechnologyMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_PatentedAndOtherTechnologyMember" xml:lang="en-US">Patented And Other Technology [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_PatentedAndOtherTechnologyMember" xml:lang="en-US">Patented and Other Technology [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_PatentedAndOtherTechnologyMember" xlink:to="lab_md_PatentedAndOtherTechnologyMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_PatentedAndOtherTechnologyMember" xml:lang="en-US">Patented and other technology.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_TradeNamesMember" xml:lang="en-US">Trade Names [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_TradeNamesMember" xml:lang="en-US">Trade Names [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TradeNamesMember" xlink:to="lab_us-gaap_TradeNamesMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" xml:lang="en-US">Finite-Lived Intangible Assets [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" xml:lang="en-US">Finite-Lived Intangible Assets [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xml:lang="en-US">Finite-Lived Intangible Assets, Accumulated Amortization</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xml:lang="en-US">Accumulated Amortization</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross" xml:lang="en-US">Finite-Lived Intangible Assets, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross" xml:lang="en-US">Gross Carrying Value</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsGross" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xml:lang="en-US">Amortization expense for existing other intangible assets, 2020</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Year Five</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xml:lang="en-US">Amortization expense for existing other intangible assets, 2024</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Year Four</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xml:lang="en-US">Amortization expense for existing other intangible assets, 2023</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Year Three</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xml:lang="en-US">Amortization expense for existing other intangible assets, 2022</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Year Two</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xml:lang="en-US">Amortization expense for existing other intangible assets, 2021</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetImpairmentCharges" xml:lang="en-US">Asset Impairment Charges</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetImpairmentCharges" xlink:to="lab_us-gaap_AssetImpairmentCharges" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xml:lang="en-US">Deferred Tax Assets, Goodwill and Intangible Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xml:lang="en-US">Deferred Tax Assets, Goodwill and Intangible Assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:to="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NetProceedsForTheManagementServicesServiceLine" xlink:label="loc_md_NetProceedsForTheManagementServicesServiceLine" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NetProceedsForTheManagementServicesServiceLine" xml:lang="en-US">Net Proceeds For The Management Services Service Line</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_NetProceedsForTheManagementServicesServiceLine" xml:lang="en-US">Net proceeds for the management services service line</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NetProceedsForTheManagementServicesServiceLine" xlink:to="lab_md_NetProceedsForTheManagementServicesServiceLine" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NetProceedsForTheManagementServicesServiceLine" xml:lang="en-US">Net proceeds for the management services service line.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Revenue</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xml:lang="en-US">Net Revenue</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Operating Income (Loss)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" xml:lang="en-US">Operating Income From Discontinued Operations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xml:lang="en-US">Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xml:lang="en-US">Preliminary gain loss on sale</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" xlink:to="lab_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxAssetsAxis" xlink:label="loc_md_DeferredTaxAssetsAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxAssetsAxis" xml:lang="en-US">Deferred Tax Assets [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxAssetsAxis" xlink:to="lab_md_DeferredTaxAssetsAxis" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxAssetsDomain" xlink:label="loc_md_DeferredTaxAssetsDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxAssetsDomain" xml:lang="en-US">Deferred Tax Assets [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxAssetsDomain" xlink:to="lab_md_DeferredTaxAssetsDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxAssetsGoodwillMember" xlink:label="loc_md_DeferredTaxAssetsGoodwillMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxAssetsGoodwillMember" xml:lang="en-US">Deferred Tax Assets Goodwill [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxAssetsGoodwillMember" xlink:to="lab_md_DeferredTaxAssetsGoodwillMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxAssetsIntangibleAssetsMember" xlink:label="loc_md_DeferredTaxAssetsIntangibleAssetsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxAssetsIntangibleAssetsMember" xml:lang="en-US">Deferred Tax Assets Intangible Assets [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxAssetsIntangibleAssetsMember" xlink:to="lab_md_DeferredTaxAssetsIntangibleAssetsMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Assets [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xml:lang="en-US">Assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" xml:lang="en-US">Cash and cash equivalents</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" xml:lang="en-US">Accounts receivable, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Prepaid and Other Assets, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" xml:lang="en-US">Prepaid expenses and other assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" xml:lang="en-US">Property and equipment, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Intangible Assets, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" xml:lang="en-US">Intangible assets, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xml:lang="en-US">Total Assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="lab_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Goodwill, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" xml:lang="en-US">Goodwill</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Liabilities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xml:lang="en-US">Liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" xml:lang="en-US">Accounts payable, accrued expenses and other liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableAndAccruedLiabilitiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xml:lang="en-US">Total Liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:to="lab_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" xml:lang="en-US">Deferred income taxes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilitiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xml:lang="en-US">Accounts Payable and Accrued Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xml:lang="en-US">Accounts payable and accrued expenses, total</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccountsPayableCurrent" xml:lang="en-US">Accounts Payable, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccountsPayableCurrent" xml:lang="en-US">Accounts payable</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableCurrent" xlink:to="lab_us-gaap_AccountsPayableCurrent" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccruedContingentConsiderationLiabilityCurrent" xlink:label="loc_md_AccruedContingentConsiderationLiabilityCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccruedContingentConsiderationLiabilityCurrent" xml:lang="en-US">Accrued Contingent Consideration Liability Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccruedContingentConsiderationLiabilityCurrent" xml:lang="en-US">Accrued contingent consideration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccruedContingentConsiderationLiabilityCurrent" xlink:to="lab_md_AccruedContingentConsiderationLiabilityCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccruedContingentConsiderationLiabilityCurrent" xml:lang="en-US">Accrued contingent consideration liability current.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccruedPayrollTaxesAndBenefitsCurrent" xlink:label="loc_md_AccruedPayrollTaxesAndBenefitsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccruedPayrollTaxesAndBenefitsCurrent" xml:lang="en-US">Accrued Payroll Taxes And Benefits Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccruedPayrollTaxesAndBenefitsCurrent" xml:lang="en-US">Accrued payroll taxes and benefits</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccruedPayrollTaxesAndBenefitsCurrent" xlink:to="lab_md_AccruedPayrollTaxesAndBenefitsCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccruedPayrollTaxesAndBenefitsCurrent" xml:lang="en-US">Accrued payroll taxes and benefits current.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedSalariesCurrent" xlink:label="loc_us-gaap_AccruedSalariesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AccruedSalariesCurrent" xml:lang="en-US">Accrued Salaries, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AccruedSalariesCurrent" xml:lang="en-US">Accrued salaries and bonuses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedSalariesCurrent" xlink:to="lab_us-gaap_AccruedSalariesCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:label="loc_us-gaap_InterestPayableCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InterestPayableCurrent" xml:lang="en-US">Interest Payable, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InterestPayableCurrent" xml:lang="en-US">Accrued interest</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPayableCurrent" xlink:to="lab_us-gaap_InterestPayableCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" xlink:label="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" xml:lang="en-US">Malpractice Loss Contingency, Accrual, Undiscounted, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" xml:lang="en-US">Accrued professional liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" xlink:to="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscountedCurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xml:lang="en-US">Other Accrued Liabilities, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xml:lang="en-US">Other accrued expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_OtherAccruedLiabilitiesCurrent" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OperatingLeasesAssetsAbstract" xlink:label="loc_md_OperatingLeasesAssetsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OperatingLeasesAssetsAbstract" xml:lang="en-US">Operating Leases Assets [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OperatingLeasesAssetsAbstract" xml:lang="en-US">Assets:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OperatingLeasesAssetsAbstract" xlink:to="lab_md_OperatingLeasesAssetsAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OperatingLeasesAssetsAbstract" xml:lang="en-US">Represents operating lease assets abstract.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OperatingLeasesLiabilitiesAbstract" xlink:label="loc_md_OperatingLeasesLiabilitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OperatingLeasesLiabilitiesAbstract" xml:lang="en-US">Operating Leases Liabilities [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OperatingLeasesLiabilitiesAbstract" xml:lang="en-US">Liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OperatingLeasesLiabilitiesAbstract" xlink:to="lab_md_OperatingLeasesLiabilitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xml:lang="en-US">Operating Lease, Weighted Average Discount Rate, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xml:lang="en-US">Weighted average discount rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OtherInformationRelatedToOperatingLeaseAbstract" xlink:label="loc_md_OtherInformationRelatedToOperatingLeaseAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OtherInformationRelatedToOperatingLeaseAbstract" xml:lang="en-US">Other Information Related to Operating Lease [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OtherInformationRelatedToOperatingLeaseAbstract" xml:lang="en-US">Other Information:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OtherInformationRelatedToOperatingLeaseAbstract" xlink:to="lab_md_OtherInformationRelatedToOperatingLeaseAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OtherInformationRelatedToOperatingLeaseAbstract" xml:lang="en-US">Representing other information related to operating lease.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xml:lang="en-US">Operating Lease, Weighted Average Remaining Lease Term</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xml:lang="en-US">Weighted-average remaining lease term</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseCost" xlink:label="loc_us-gaap_OperatingLeaseCost" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseCost" xml:lang="en-US">Operating Lease, Cost</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeaseCost" xml:lang="en-US">Operating lease costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseCost" xlink:to="lab_us-gaap_OperatingLeaseCost" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableLeaseCost" xlink:label="loc_us-gaap_VariableLeaseCost" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_VariableLeaseCost" xml:lang="en-US">Variable Lease, Cost</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_VariableLeaseCost" xml:lang="en-US">Variable lease costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableLeaseCost" xlink:to="lab_us-gaap_VariableLeaseCost" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OperatingLeasesOtherCosts" xlink:label="loc_md_OperatingLeasesOtherCosts" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OperatingLeasesOtherCosts" xml:lang="en-US">Operating Leases Other Costs</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_md_OperatingLeasesOtherCosts" xml:lang="en-US">Other operating lease costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OperatingLeasesOtherCosts" xlink:to="lab_md_OperatingLeasesOtherCosts" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OperatingLeasesOtherCosts" xml:lang="en-US">Represents other costs of operating leases.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseCost" xlink:label="loc_us-gaap_LeaseCost" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LeaseCost" xml:lang="en-US">Lease, Cost</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_LeaseCost" xml:lang="en-US">Total operating lease costs</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCost" xlink:to="lab_us-gaap_LeaseCost" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_OtherEquipmentRent" xlink:label="loc_md_OtherEquipmentRent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_OtherEquipmentRent" xml:lang="en-US">Other Equipment Rent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_OtherEquipmentRent" xml:lang="en-US">Other equipment rent</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_OtherEquipmentRent" xlink:to="lab_md_OtherEquipmentRent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_OtherEquipmentRent" xml:lang="en-US">Other equipment rent.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:label="loc_us-gaap_OperatingLeasePayments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeasePayments" xml:lang="en-US">Operating Lease, Payments</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_OperatingLeasePayments" xml:lang="en-US">Operating cash flows for operating leases</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasePayments" xlink:to="lab_us-gaap_OperatingLeasePayments" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Two</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xml:lang="en-US">2021</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Three</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xml:lang="en-US">2022</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Four</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xml:lang="en-US">2023</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Five</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xml:lang="en-US">2024</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due after Year Five</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xml:lang="en-US">Thereafter</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xml:lang="en-US">Total minimum lease payments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xml:lang="en-US">Lessee, Operating Lease, Liability, Undiscounted Excess Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xml:lang="en-US">Less: Amount of payments representing interest</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLeaseLiability" xml:lang="en-US">Operating Lease, Liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_OperatingLeaseLiability" xml:lang="en-US">Present value of future minimum lease payments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiability" xlink:to="lab_us-gaap_OperatingLeaseLiability" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xml:lang="en-US">2020</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccruedProfessionalLiability" xlink:label="loc_md_AccruedProfessionalLiability" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccruedProfessionalLiability" xml:lang="en-US">Accrued Professional Liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccruedProfessionalLiability" xml:lang="en-US">Accrued professional liability incurred and loss reserves reported for claims</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccruedProfessionalLiability" xlink:to="lab_md_AccruedProfessionalLiability" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccruedProfessionalLiability" xml:lang="en-US">Accrued professional liability.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InsuranceSettlementsReceivable" xlink:label="loc_us-gaap_InsuranceSettlementsReceivable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_InsuranceSettlementsReceivable" xml:lang="en-US">Insurance Settlements Receivable</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_InsuranceSettlementsReceivable" xml:lang="en-US">Insurance receivables</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InsuranceSettlementsReceivable" xlink:to="lab_us-gaap_InsuranceSettlementsReceivable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xlink:label="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xml:lang="en-US">Malpractice Loss Contingency, Accrual, Undiscounted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xml:lang="en-US">Total accrued professional liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xml:lang="en-US">Balance at beginning of year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xml:lang="en-US">Balance at end of year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" xlink:to="lab_us-gaap_MalpracticeLossContingencyAccrualUndiscounted" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SelfInsuranceReserveCurrent" xlink:label="loc_us-gaap_SelfInsuranceReserveCurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SelfInsuranceReserveCurrent" xml:lang="en-US">Self Insurance Reserve, Current</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SelfInsuranceReserveCurrent" xml:lang="en-US">Accrued professional liability incurred but loss reserves not reported for claims</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SelfInsuranceReserveCurrent" xlink:to="lab_us-gaap_SelfInsuranceReserveCurrent" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" xlink:label="loc_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" xml:lang="en-US">Accrued Professional Liabilities Assumed Through Acquisition</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" xml:lang="en-US">Assumed liabilities through acquisition</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" xlink:to="lab_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AccruedProfessionalLiabilitiesAssumedThroughAcquisition" xml:lang="en-US">Accrued professional liabilities assumed through acquisition.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" xlink:label="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" xml:lang="en-US">Malpractice Loss Contingency, Claims Incurred in Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" xml:lang="en-US">Claim payments related to Current year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" xlink:to="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" xlink:label="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" xml:lang="en-US">Malpractice Loss Contingency, Claims Incurred in Prior Periods</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" xml:lang="en-US">Claim payments related to Prior years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" xlink:to="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredInPriorPeriods" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MalpracticeLossContingencyClaimsIncurredNet" xlink:label="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredNet" xml:lang="en-US">Malpractice Loss Contingency, Claims Incurred, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:label="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredNet" xml:lang="en-US">Total payments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MalpracticeLossContingencyClaimsIncurredNet" xlink:to="lab_us-gaap_MalpracticeLossContingencyClaimsIncurredNet" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_MalpracticeLossContingencyProvisionForLosses" xlink:label="loc_md_MalpracticeLossContingencyProvisionForLosses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_MalpracticeLossContingencyProvisionForLosses" xml:lang="en-US">Malpractice Loss Contingency Provision For Losses</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_md_MalpracticeLossContingencyProvisionForLosses" xml:lang="en-US">Total provision for losses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_MalpracticeLossContingencyProvisionForLosses" xlink:to="lab_md_MalpracticeLossContingencyProvisionForLosses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_MalpracticeLossContingencyProvisionForLosses" xml:lang="en-US">Malpractice loss contingency provision for losses.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ProvisionAdjustmentForLossesRelatedToCurrentYear" xlink:label="loc_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" xml:lang="en-US">Provision Adjustment For Losses Related To Current Year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" xml:lang="en-US">Provision (adjustment) for losses related to Current year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" xlink:to="lab_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToCurrentYear" xml:lang="en-US">Provision (adjustment) for losses related to current year.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ProvisionAdjustmentForLossesRelatedToPriorYear" xlink:label="loc_md_ProvisionAdjustmentForLossesRelatedToPriorYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToPriorYear" xml:lang="en-US">Provision Adjustment For Losses Related To Prior Year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToPriorYear" xml:lang="en-US">Provision (adjustment) for losses related to Prior years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ProvisionAdjustmentForLossesRelatedToPriorYear" xlink:to="lab_md_ProvisionAdjustmentForLossesRelatedToPriorYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ProvisionAdjustmentForLossesRelatedToPriorYear" xml:lang="en-US">Provision (adjustment) for losses related to prior year.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LineOfCreditFacilityTable" xml:lang="en-US">Line of Credit Facility [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LineOfCreditFacilityTable" xml:lang="en-US">Line of Credit Facility [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityTable" xlink:to="lab_us-gaap_LineOfCreditFacilityTable" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" xlink:label="loc_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" xml:lang="en-US">Five Point Two Five Percent Senior Unsecured Notes Due Two Thousand Twenty Three [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" xml:lang="en-US">5.25% Senior Unsecured Notes Due 2023 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" xlink:to="lab_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_FivePointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentyThreeMember" xml:lang="en-US">Five point two five percent senior unsecured notes due two thousand twenty three.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LetterOfCreditMember" xml:lang="en-US">Letter of Credit [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LetterOfCreditMember" xml:lang="en-US">Letters of Credit [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LetterOfCreditMember" xlink:to="lab_us-gaap_LetterOfCreditMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" xlink:label="loc_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" xml:lang="en-US">Six Point Two Five Percent Senior Unsecured Notes Due Two Thousand Twenty Seven [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" xml:lang="en-US">6.25% Senior Unsecured Notes Due 2027 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" xlink:to="lab_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_SixPointTwoFivePercentSeniorUnsecuredNotesDueTwoThousandTwentySevenMember" xml:lang="en-US">Six point two five percent senior unsecured notes due two thousand twenty seven.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_UnsecuredRevolvingCreditFacilityMember" xlink:label="loc_md_UnsecuredRevolvingCreditFacilityMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_UnsecuredRevolvingCreditFacilityMember" xml:lang="en-US">Unsecured Revolving Credit Facility [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_UnsecuredRevolvingCreditFacilityMember" xml:lang="en-US">Unsecured Revolving Credit Facility [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_UnsecuredRevolvingCreditFacilityMember" xlink:to="lab_md_UnsecuredRevolvingCreditFacilityMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_UnsecuredRevolvingCreditFacilityMember" xml:lang="en-US">Unsecured Revolving Credit Facility [Member]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AlternateBaseRateMember" xlink:label="loc_md_AlternateBaseRateMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AlternateBaseRateMember" xml:lang="en-US">Alternate Base Rate [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AlternateBaseRateMember" xml:lang="en-US">Alternate Base Rate [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AlternateBaseRateMember" xlink:to="lab_md_AlternateBaseRateMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AlternateBaseRateMember" xml:lang="en-US">Alternate base rate.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ApplicableMarginRateMember" xlink:label="loc_md_ApplicableMarginRateMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ApplicableMarginRateMember" xml:lang="en-US">Applicable Margin Rate [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ApplicableMarginRateMember" xml:lang="en-US">Applicable Margin Rate [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ApplicableMarginRateMember" xlink:to="lab_md_ApplicableMarginRateMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ApplicableMarginRateMember" xml:lang="en-US">Applicable margin rate.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xml:lang="en-US">Debt Instrument [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xml:lang="en-US">Debt Instrument [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="lab_us-gaap_DebtInstrumentLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xml:lang="en-US">Debt Instrument, Basis Spread on Variable Rate</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xml:lang="en-US">Debt instrument, variable interest rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:to="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:label="loc_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xml:lang="en-US">Debt Instrument, Description of Variable Rate Basis</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xml:lang="en-US">Debt instrument, interest rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:to="lab_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xml:lang="en-US">Debt Instrument, Face Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xml:lang="en-US">Aggregate principal amount of debt</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFaceAmount" xlink:to="lab_us-gaap_DebtInstrumentFaceAmount" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xml:lang="en-US">Debt Instrument, Interest Rate, Stated Percentage</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xml:lang="en-US">Debt instrument interest rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentMaturityDateDescription" xlink:label="loc_us-gaap_DebtInstrumentMaturityDateDescription" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentMaturityDateDescription" xml:lang="en-US">Debt Instrument, Maturity Date, Description</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentMaturityDateDescription" xml:lang="en-US">Debt instrument maturity date description</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentMaturityDateDescription" xlink:to="lab_us-gaap_DebtInstrumentMaturityDateDescription" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentMaturityYear" xlink:label="loc_md_DebtInstrumentMaturityYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentMaturityYear" xml:lang="en-US">Debt Instrument Maturity Year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentMaturityYear" xml:lang="en-US">Debt instrument, maturity year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentMaturityYear" xlink:to="lab_md_DebtInstrumentMaturityYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentMaturityYear" xml:lang="en-US">Debt instrument maturity year.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" xml:lang="en-US">Debt Instrument, Redemption Price, Percentage</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" xml:lang="en-US">Redemption price percentage of aggregate principal amount redeemed</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" xml:lang="en-US">Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" xml:lang="en-US">Redemption percentage of principal amount</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount" xml:lang="en-US">Letters of Credit Outstanding, Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount" xml:lang="en-US">Letters of credit outstanding amount</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LettersOfCreditOutstandingAmount" xlink:to="lab_us-gaap_LettersOfCreditOutstandingAmount" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationDate1" xlink:label="loc_us-gaap_LineOfCreditFacilityExpirationDate1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LineOfCreditFacilityExpirationDate1" xml:lang="en-US">Line of Credit Facility, Expiration Date</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LineOfCreditFacilityExpirationDate1" xml:lang="en-US">Line of Credit facility, maturity date</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityExpirationDate1" xlink:to="lab_us-gaap_LineOfCreditFacilityExpirationDate1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xml:lang="en-US">Line of Credit Facility, Maximum Borrowing Capacity</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xml:lang="en-US">Line of Credit facility, borrowing capacity</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:to="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xml:lang="en-US">Line of Credit Facility, Remaining Borrowing Capacity</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xml:lang="en-US">Line of Credit facility, available balance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:to="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LongTermDebt" xml:lang="en-US">Long-term Debt</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LongTermDebt" xml:lang="en-US">Long term debt</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebt" xlink:to="lab_us-gaap_LongTermDebt" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" xml:lang="en-US">Debt Instrument, Periodic Payment, Interest</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" xml:lang="en-US">Interest accrued periodically</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:to="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" xml:lang="en-US">Debt Instrument, Redemption, Period [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" xml:lang="en-US">Debt Instrument, Redemption, Period [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" xml:lang="en-US">Debt Instrument, Redemption, Period [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" xml:lang="en-US">Debt Instrument, Redemption, Period [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" xlink:label="loc_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" xml:lang="en-US">Debt Instrument Redemption Period Before Two Thousand Twenty Two [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" xml:lang="en-US">Redemption Before 2022 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" xlink:to="lab_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentRedemptionPeriodBeforeTwoThousandTwentyTwoMember" xml:lang="en-US">Debt instrument redemption period before two thousand twenty two.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodFiveMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFiveMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodFiveMember" xml:lang="en-US">Debt Instrument, Redemption, Period Five [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodFiveMember" xml:lang="en-US">Redemption in 2024 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodFiveMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodFiveMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodFourMember" xml:lang="en-US">Debt Instrument, Redemption, Period Four [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodFourMember" xml:lang="en-US">Redemption in 2023 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodFourMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" xlink:label="loc_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" xml:lang="en-US">Debt Instrument Redemption Period Six And Thereafter [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" xml:lang="en-US">Redemption in 2025 and Thereafter [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" xlink:to="lab_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentRedemptionPeriodSixAndThereafterMember" xml:lang="en-US">Debt instrument redemption period six and thereafter.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" xlink:label="loc_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" xml:lang="en-US">Debt Instrument Redemption Period Three And Thereafter [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" xml:lang="en-US">Redemption in 2021 and Thereafter [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" xlink:to="lab_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentRedemptionPeriodThreeAndThereafterMember" xml:lang="en-US">Debt Instrument Redemption Period Three And Thereafter [Member]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xml:lang="en-US">Debt Instrument, Redemption, Period Three [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xml:lang="en-US">Redemption in 2022 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodThreeMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xml:lang="en-US">Debt Instrument, Redemption, Period Two [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xml:lang="en-US">Redemption in 2020 [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherOwnershipInterestsByNameAxis" xlink:label="loc_us-gaap_OtherOwnershipInterestsByNameAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherOwnershipInterestsByNameAxis" xml:lang="en-US">Other Ownership Interests Name [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherOwnershipInterestsByNameAxis" xml:lang="en-US">Other Ownership Interests Name [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherOwnershipInterestsByNameAxis" xlink:to="lab_us-gaap_OtherOwnershipInterestsByNameAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherOwnershipInterestsNameDomain" xlink:label="loc_us-gaap_OtherOwnershipInterestsNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OtherOwnershipInterestsNameDomain" xml:lang="en-US">Other Ownership Interests, Name [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OtherOwnershipInterestsNameDomain" xml:lang="en-US">Other Ownership Interests, Name [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherOwnershipInterestsNameDomain" xlink:to="lab_us-gaap_OtherOwnershipInterestsNameDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_ChangeInControlMember" xlink:label="loc_md_ChangeInControlMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_ChangeInControlMember" xml:lang="en-US">Change In Control [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_ChangeInControlMember" xml:lang="en-US">Change In Control [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_ChangeInControlMember" xlink:to="lab_md_ChangeInControlMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_ChangeInControlMember" xml:lang="en-US">Change in control.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_VariableRateAxis" xml:lang="en-US">Variable Rate [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_VariableRateAxis" xml:lang="en-US">Variable Rate [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateAxis" xlink:to="lab_us-gaap_VariableRateAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_VariableRateDomain" xml:lang="en-US">Variable Rate [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_VariableRateDomain" xml:lang="en-US">Variable Rate [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateDomain" xlink:to="lab_us-gaap_VariableRateDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FederalFundsEffectiveSwapRateMember" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FederalFundsEffectiveSwapRateMember" xml:lang="en-US">Federal Funds Effective Swap Rate [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FederalFundsEffectiveSwapRateMember" xml:lang="en-US">Federal Funds Rate [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:to="lab_us-gaap_FederalFundsEffectiveSwapRateMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" xml:lang="en-US">London Interbank Offered Rate (LIBOR) [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" xml:lang="en-US">LIBOR [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:to="lab_us-gaap_LondonInterbankOfferedRateLIBORMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementScenarioAxis" xlink:label="loc_srt_StatementScenarioAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_StatementScenarioAxis" xml:lang="en-US">Scenario [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_StatementScenarioAxis" xml:lang="en-US">Scenario [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_StatementScenarioAxis" xlink:to="lab_srt_StatementScenarioAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="loc_srt_ScenarioUnspecifiedDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_ScenarioUnspecifiedDomain" xml:lang="en-US">Scenario [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_ScenarioUnspecifiedDomain" xml:lang="en-US">Scenario, Unspecified [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScenarioUnspecifiedDomain" xlink:to="lab_srt_ScenarioUnspecifiedDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" xlink:label="loc_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" xml:lang="en-US">Redeem Up to Thirty Five Percentage of Aggregate Principal Amount [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" xml:lang="en-US">Redeem up to 35% of Aggregate Principal Amount [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" xlink:to="lab_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_RedeemUpToThirtyFivePercentageOfAggregatePrincipalAmountMember" xml:lang="en-US">Redeem up to thirty five percentage of aggregate principal amount.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentTable" xml:lang="en-US">Schedule of Long-term Debt Instruments [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentTable" xml:lang="en-US">Schedule of Long-term Debt Instruments [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentTable" xlink:to="lab_us-gaap_DebtInstrumentTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xml:lang="en-US">Revolving Credit Facility [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xml:lang="en-US">Revolving Credit Facility [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevolvingCreditFacilityMember" xlink:to="lab_us-gaap_RevolvingCreditFacilityMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount" xml:lang="en-US">Long-term Debt, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount" xml:lang="en-US">Debt instrument principal amount</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentCarryingAmount" xlink:to="lab_us-gaap_DebtInstrumentCarryingAmount" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnamortizedDebtIssuanceExpense" xml:lang="en-US">Unamortized Debt Issuance Expense</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_UnamortizedDebtIssuanceExpense" xml:lang="en-US">Unamortized debt issuance cost</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnamortizedDebtIssuanceExpense" xlink:to="lab_us-gaap_UnamortizedDebtIssuanceExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFairValueDisclosureAbstract" xlink:label="loc_us-gaap_DebtInstrumentFairValueDisclosureAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DebtInstrumentFairValueDisclosureAbstract" xml:lang="en-US">Debt Instrument, Fair Value Disclosure [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFairValueDisclosureAbstract" xlink:to="lab_us-gaap_DebtInstrumentFairValueDisclosureAbstract" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentFairValueTable" xlink:label="loc_md_DebtInstrumentFairValueTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentFairValueTable" xml:lang="en-US">Debt Instrument Fair Value [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentFairValueTable" xml:lang="en-US">Debt Instrument Fair Value [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentFairValueTable" xlink:to="lab_md_DebtInstrumentFairValueTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentFairValueTable" xml:lang="en-US">Debt Instrument Fair Value [Table]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DebtInstrumentFairValueLineItems" xlink:label="loc_md_DebtInstrumentFairValueLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DebtInstrumentFairValueLineItems" xml:lang="en-US">Debt Instrument Fair Value [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DebtInstrumentFairValueLineItems" xml:lang="en-US">Debt Instrument Fair Value [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DebtInstrumentFairValueLineItems" xlink:to="lab_md_DebtInstrumentFairValueLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DebtInstrumentFairValueLineItems" xml:lang="en-US">Debt Instrument Fair Value [Line Items]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FairValueByMeasurementBasisAxis" xml:lang="en-US">Measurement Basis [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FairValueByMeasurementBasisAxis" xml:lang="en-US">Measurement Basis [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis" xlink:to="lab_us-gaap_FairValueByMeasurementBasisAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PortionAtFairValueFairValueDisclosureMember" xml:lang="en-US">Portion at Fair Value Measurement [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:to="lab_us-gaap_PortionAtFairValueFairValueDisclosureMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EstimateOfFairValueFairValueDisclosureMember" xml:lang="en-US">Estimate of Fair Value Measurement [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:to="lab_us-gaap_EstimateOfFairValueFairValueDisclosureMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiability" xlink:label="loc_us-gaap_FinanceLeaseLiability" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FinanceLeaseLiability" xml:lang="en-US">Finance Lease, Liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FinanceLeaseLiability" xml:lang="en-US">Finance lease obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiability" xlink:to="lab_us-gaap_FinanceLeaseLiability" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xml:lang="en-US">Finance Lease, Liability, Noncurrent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xml:lang="en-US">Long-term portion</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit" xml:lang="en-US">Current Federal Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit" xml:lang="en-US">Federal, Current</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentFederalTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xml:lang="en-US">Current State and Local Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xml:lang="en-US">State, Current</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xml:lang="en-US">Deferred Federal Income Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xml:lang="en-US">Federal, Deferred</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xml:lang="en-US">Deferred State and Local Income Tax Expense (Benefit)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xml:lang="en-US">State, Deferred</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" xlink:label="loc_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" xml:lang="en-US">Federal Income Tax Expense (Benefit), Continuing Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" xml:lang="en-US">Federal income tax provision, Total</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" xlink:to="lab_us-gaap_FederalIncomeTaxExpenseBenefitContinuingOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xlink:label="loc_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xml:lang="en-US">State and Local Income Tax Expense (Benefit), Continuing Operations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xml:lang="en-US">State income tax provision, Total</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xlink:to="lab_us-gaap_StateAndLocalIncomeTaxExpenseBenefitContinuingOperations" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_IncomeTaxTable" xlink:label="loc_md_IncomeTaxTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_IncomeTaxTable" xml:lang="en-US">Income Tax [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_IncomeTaxTable" xml:lang="en-US">Income Tax [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_IncomeTaxTable" xlink:to="lab_md_IncomeTaxTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_IncomeTaxTable" xml:lang="en-US">Income Tax [Table]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ChangeInAccountingEstimateByTypeAxis" xml:lang="en-US">Change in Accounting Estimate by Type [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ChangeInAccountingEstimateByTypeAxis" xml:lang="en-US">Change in Accounting Estimate by Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis" xlink:to="lab_us-gaap_ChangeInAccountingEstimateByTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ChangeInAccountingEstimateTypeDomain" xml:lang="en-US">Change in Accounting Estimate, Type [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ChangeInAccountingEstimateTypeDomain" xml:lang="en-US">Change in Accounting Estimate, Type [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain" xlink:to="lab_us-gaap_ChangeInAccountingEstimateTypeDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_IncomeTaxLineItems" xlink:label="loc_md_IncomeTaxLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_IncomeTaxLineItems" xml:lang="en-US">Income Tax [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_IncomeTaxLineItems" xml:lang="en-US">Income Tax [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_IncomeTaxLineItems" xlink:to="lab_md_IncomeTaxLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_IncomeTaxLineItems" xml:lang="en-US">Income Tax [Line Items]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xml:lang="en-US">Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xml:lang="en-US">Operating loss carryforwards not subject to expiration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xlink:to="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xml:lang="en-US">Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xml:lang="en-US">Operating loss carryforwards subject to expiration</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:to="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xml:lang="en-US">Effective tax rate</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xml:lang="en-US">Income tax provision</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateContinuingOperations" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xml:lang="en-US">Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xml:lang="en-US">Tax at statutory rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" xml:lang="en-US">Income Tax Examination, Penalties and Interest Accrued</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" xml:lang="en-US">Company's accrued liability for interest and penalties related to income tax liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" xlink:to="lab_us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xml:lang="en-US">Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xml:lang="en-US">Income tax benefit resulting from the reduction of deferred tax liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_IncomeTaxExpenseForExcessTaxDeficiencies" xlink:label="loc_md_IncomeTaxExpenseForExcessTaxDeficiencies" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_IncomeTaxExpenseForExcessTaxDeficiencies" xml:lang="en-US">Income Tax Expense For Excess Tax Deficiencies</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_IncomeTaxExpenseForExcessTaxDeficiencies" xml:lang="en-US">Income tax expense for excess tax deficiencies</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_IncomeTaxExpenseForExcessTaxDeficiencies" xlink:to="lab_md_IncomeTaxExpenseForExcessTaxDeficiencies" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_IncomeTaxExpenseForExcessTaxDeficiencies" xml:lang="en-US">Income tax expense for excess tax deficiencies.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredLiabilities" xml:lang="en-US">Increase (Decrease) in Deferred Liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredLiabilities" xml:lang="en-US">Increase (decrease) in net deferred tax liability</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInDeferredLiabilities" xlink:to="lab_us-gaap_IncreaseDecreaseInDeferredLiabilities" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NetOperatingLossCarryForwardsExpirationDate" xlink:label="loc_md_NetOperatingLossCarryForwardsExpirationDate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NetOperatingLossCarryForwardsExpirationDate" xml:lang="en-US">Net Operating Loss Carry Forwards Expiration Date</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_NetOperatingLossCarryForwardsExpirationDate" xml:lang="en-US">Expiration period of operating loss carryforwards</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NetOperatingLossCarryForwardsExpirationDate" xlink:to="lab_md_NetOperatingLossCarryForwardsExpirationDate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NetOperatingLossCarryForwardsExpirationDate" xml:lang="en-US">Net operating loss carry forwards expiration date.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OpenTaxYear" xlink:label="loc_us-gaap_OpenTaxYear" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OpenTaxYear" xml:lang="en-US">Open Tax Year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OpenTaxYear" xml:lang="en-US">Federal and state income tax examinations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OpenTaxYear" xlink:to="lab_us-gaap_OpenTaxYear" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_OperatingLossCarryforwards" xml:lang="en-US">Operating Loss Carryforwards</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_OperatingLossCarryforwards" xml:lang="en-US">Net operating loss carryforwards for federal and state tax</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLossCarryforwards" xlink:to="lab_us-gaap_OperatingLossCarryforwards" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xml:lang="en-US">Unrecognized Tax Benefits</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xml:lang="en-US">Uncertain tax position liability</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xml:lang="en-US">Balance at beginning of year</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xml:lang="en-US">Balance at end of year</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefits" xlink:to="lab_us-gaap_UnrecognizedTaxBenefits" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" xml:lang="en-US">Unrecognized Tax Benefits, Period Increase (Decrease)</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" xml:lang="en-US">Increase (decrease) in uncertain tax position</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xml:lang="en-US">Unrecognized Tax Benefits that Would Impact Effective Tax Rate</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xml:lang="en-US">Unrecognized tax benefits that would impact effective tax rate</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xml:lang="en-US">Deferred Tax Assets, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xml:lang="en-US">Deferred tax assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" xml:lang="en-US">Net deferred tax assets</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:to="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" xml:lang="en-US">Effective income tax rate reconciliation nondeductible portion of goodwill impairment charge</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" xlink:to="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseImpairmentLosses" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CapitalLossesIncurred" xlink:label="loc_md_CapitalLossesIncurred" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CapitalLossesIncurred" xml:lang="en-US">Capital Losses Incurred</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CapitalLossesIncurred" xml:lang="en-US">Capital losses incurred</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CapitalLossesIncurred" xlink:to="lab_md_CapitalLossesIncurred" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CapitalLossesIncurred" xml:lang="en-US">Capital losses incurred.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CapitalLossCarryforwardsExpirationDate" xlink:label="loc_md_CapitalLossCarryforwardsExpirationDate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CapitalLossCarryforwardsExpirationDate" xml:lang="en-US">Capital Loss Carryforwards Expiration Date</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CapitalLossCarryforwardsExpirationDate" xml:lang="en-US">Capital loss carryforwards, expiration date</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CapitalLossCarryforwardsExpirationDate" xlink:to="lab_md_CapitalLossCarryforwardsExpirationDate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CapitalLossCarryforwardsExpirationDate" xml:lang="en-US">Capital loss carryforwards, expiration date.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CapitalLossCarryforwardsValuationAllowance" xlink:label="loc_md_CapitalLossCarryforwardsValuationAllowance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CapitalLossCarryforwardsValuationAllowance" xml:lang="en-US">Capital Loss Carryforwards Valuation Allowance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CapitalLossCarryforwardsValuationAllowance" xml:lang="en-US">Capital loss carryforwards, valuation allowance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CapitalLossCarryforwardsValuationAllowance" xlink:to="lab_md_CapitalLossCarryforwardsValuationAllowance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CapitalLossCarryforwardsValuationAllowance" xml:lang="en-US">Capital loss carryforwards, valuation allowance.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaap_DeferredTaxLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xml:lang="en-US">Deferred Tax Liabilities, Net</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xml:lang="en-US">Net deferred tax liabilities</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xml:lang="en-US">Net deferred tax liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilities" xlink:to="lab_us-gaap_DeferredTaxLiabilities" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" xlink:label="loc_us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" xml:lang="en-US">Nature of Uncertainty [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" xml:lang="en-US">Nature of Uncertainty [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" xlink:to="lab_us-gaap_ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItemAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" xml:lang="en-US">Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Nature of Uncertainty [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" xml:lang="en-US">Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Nature of Uncertainty [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" xlink:to="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleNatureOfUncertaintyDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxPeriodAxis" xlink:label="loc_us-gaap_TaxPeriodAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_TaxPeriodAxis" xml:lang="en-US">Tax Period [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_TaxPeriodAxis" xml:lang="en-US">Tax Period [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TaxPeriodAxis" xlink:to="lab_us-gaap_TaxPeriodAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:label="loc_us-gaap_TaxPeriodDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_TaxPeriodDomain" xml:lang="en-US">Tax Period [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_TaxPeriodDomain" xml:lang="en-US">Tax Period [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TaxPeriodDomain" xlink:to="lab_us-gaap_TaxPeriodDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarliestTaxYearMember" xlink:label="loc_us-gaap_EarliestTaxYearMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EarliestTaxYearMember" xml:lang="en-US">Earliest Tax Year [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EarliestTaxYearMember" xml:lang="en-US">Earliest Tax Year [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarliestTaxYearMember" xlink:to="lab_us-gaap_EarliestTaxYearMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LatestTaxYearMember" xlink:label="loc_us-gaap_LatestTaxYearMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_LatestTaxYearMember" xml:lang="en-US">Latest Tax Year [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_LatestTaxYearMember" xml:lang="en-US">Latest Tax Year [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LatestTaxYearMember" xlink:to="lab_us-gaap_LatestTaxYearMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScenarioForecastMember" xlink:label="loc_srt_ScenarioForecastMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_srt_ScenarioForecastMember" xml:lang="en-US">Forecast [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_srt_ScenarioForecastMember" xml:lang="en-US">Scenario, Forecast [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScenarioForecastMember" xlink:to="lab_srt_ScenarioForecastMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xml:lang="en-US">Change in valuation allowance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xml:lang="en-US">Change in tax law</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xml:lang="en-US">Non-deductible expenses</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Other Adjustments, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments" xml:lang="en-US">Change in accrual estimates relating to uncertain tax positions</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" xml:lang="en-US">Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" xml:lang="en-US">Other, net</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xml:lang="en-US">Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xml:lang="en-US">State income tax, net of federal benefit</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" xml:lang="en-US">Impairments</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseImpairmentLosses" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" xlink:label="loc_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" xml:lang="en-US">Effective Income Tax Reconciliation Capital Loss On Liquidation Percentage</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" xml:lang="en-US">Capital loss on liquidation</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" xlink:to="lab_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_EffectiveIncomeTaxReconciliationCapitalLossOnLiquidationPercentage" xml:lang="en-US">Effective income tax reconciliation capital loss on liquidation percentage.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:label="loc_us-gaap_DeferredTaxAssetsGross" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsGross" xml:lang="en-US">Deferred Tax Assets, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsGross" xml:lang="en-US">Deferred tax assets before valuation allowance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsGross" xlink:to="lab_us-gaap_DeferredTaxAssetsGross" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_us-gaap_DeferredTaxAssetsNet" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsNet" xml:lang="en-US">Deferred Tax Assets, Net of Valuation Allowance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsNet" xml:lang="en-US">Deferred tax assets, net of valuation allowance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsNet" xlink:to="lab_us-gaap_DeferredTaxAssetsNet" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:label="loc_us-gaap_DeferredTaxAssetsOther" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsOther" xml:lang="en-US">Deferred Tax Assets, Other</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsOther" xml:lang="en-US">Other</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOther" xlink:to="lab_us-gaap_DeferredTaxAssetsOther" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" xlink:label="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" xml:lang="en-US">Deferred Tax Assets, Property, Plant and Equipment</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" xml:lang="en-US">Property and equipment</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" xlink:to="lab_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xml:lang="en-US">Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xml:lang="en-US">Stock-based compensation</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xml:lang="en-US">Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xml:lang="en-US">Allowance for uncollectible accounts</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xml:lang="en-US">Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xml:lang="en-US">Reserves and accruals</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xml:lang="en-US">Deferred Tax Assets, Valuation Allowance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xml:lang="en-US">Less: Valuation allowance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="lab_us-gaap_DeferredTaxAssetsValuationAllowance" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesAbstract" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesAbstract" xml:lang="en-US">Deferred Tax Liabilities, Gross [Abstract]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesAbstract" xml:lang="en-US">Gross deferred tax liabilities:</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesAbstract" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesAbstract" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities" xml:lang="en-US">Deferred Tax Liabilities, Gross</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities" xml:lang="en-US">Total deferred tax liabilities</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities" xlink:to="lab_us-gaap_DeferredIncomeTaxLiabilities" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxLiabilitiesChangeInAccountingMethod" xlink:label="loc_md_DeferredTaxLiabilitiesChangeInAccountingMethod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxLiabilitiesChangeInAccountingMethod" xml:lang="en-US">Deferred Tax Liabilities Change in Accounting Method</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_md_DeferredTaxLiabilitiesChangeInAccountingMethod" xml:lang="en-US">Accounting method changes</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxLiabilitiesChangeInAccountingMethod" xlink:to="lab_md_DeferredTaxLiabilitiesChangeInAccountingMethod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DeferredTaxLiabilitiesChangeInAccountingMethod" xml:lang="en-US">Deferred tax liabilities change in accounting method.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" xml:lang="en-US">Deferred Tax Liabilities, Deferred Expense, Reserves and Accruals</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" xml:lang="en-US">Accrual to cash adjustment</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xml:lang="en-US">Deferred Tax Liabilities, Intangible Assets</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xml:lang="en-US">Amortization</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther" xml:lang="en-US">Deferred Tax Liabilities, Other</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther" xml:lang="en-US">Other</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesOther" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesOther" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_DeferredTaxAssetsTotalLossCarryforwards" xlink:label="loc_md_DeferredTaxAssetsTotalLossCarryforwards" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_DeferredTaxAssetsTotalLossCarryforwards" xml:lang="en-US">Deferred Tax Assets Total Loss Carryforwards</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_DeferredTaxAssetsTotalLossCarryforwards" xml:lang="en-US">Loss carryforwards</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_DeferredTaxAssetsTotalLossCarryforwards" xlink:to="lab_md_DeferredTaxAssetsTotalLossCarryforwards" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_DeferredTaxAssetsTotalLossCarryforwards" xml:lang="en-US">Deferred tax assets total loss carryforwards.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xml:lang="en-US">Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xml:lang="en-US">Decreases related to prior year tax positions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xml:lang="en-US">Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xml:lang="en-US">Increases related to current year tax positions</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xml:lang="en-US">Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xml:lang="en-US">Increases related to prior year tax positions</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xml:lang="en-US">Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xml:lang="en-US">Decreases related to lapse of statutes of limitation</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xml:lang="en-US">Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xml:lang="en-US">Antidilutive securities not included in the diluted net income per common share calculation</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xml:lang="en-US">Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xml:lang="en-US">Weighted average number of dilutive common share equivalents</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:to="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xml:lang="en-US">Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xml:lang="en-US">Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AwardTypeAxis" xml:lang="en-US">Award Type [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AwardTypeAxis" xml:lang="en-US">Award Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="lab_us-gaap_AwardTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xml:lang="en-US">Equity Award [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xml:lang="en-US">Equity Award [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xml:lang="en-US">Employee Stock Option [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xml:lang="en-US">Stock Option [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeStockOptionMember" xlink:to="lab_us-gaap_EmployeeStockOptionMember" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_RestrictedAndDeferredStockUnitsMember" xlink:label="loc_md_RestrictedAndDeferredStockUnitsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_RestrictedAndDeferredStockUnitsMember" xml:lang="en-US">Restricted And Deferred Stock Units [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_RestrictedAndDeferredStockUnitsMember" xml:lang="en-US">Restricted and Deferred Stock Units [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_RestrictedAndDeferredStockUnitsMember" xlink:to="lab_md_RestrictedAndDeferredStockUnitsMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_RestrictedAndDeferredStockUnitsMember" xml:lang="en-US">Restricted and deferred stock units.</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_RestrictedStockMember" xml:lang="en-US">Restricted Stock [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_RestrictedStockMember" xml:lang="en-US">Restricted Stock [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedStockMember" xlink:to="lab_us-gaap_RestrictedStockMember" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PlanNameAxis" xml:lang="en-US">Plan Name [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PlanNameAxis" xml:lang="en-US">Plan Name [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameAxis" xlink:to="lab_us-gaap_PlanNameAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_PlanNameDomain" xml:lang="en-US">Plan Name [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_PlanNameDomain" xml:lang="en-US">Plan Name [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameDomain" xlink:to="lab_us-gaap_PlanNameDomain" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_AmendedAndRestatedTwoThousandEightPlanMember" xlink:label="loc_md_AmendedAndRestatedTwoThousandEightPlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_AmendedAndRestatedTwoThousandEightPlanMember" xml:lang="en-US">Amended and Restated Two Thousand Eight Plan [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_AmendedAndRestatedTwoThousandEightPlanMember" xml:lang="en-US">Amended and Restated 2008 Plan [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_AmendedAndRestatedTwoThousandEightPlanMember" xlink:to="lab_md_AmendedAndRestatedTwoThousandEightPlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_AmendedAndRestatedTwoThousandEightPlanMember" xml:lang="en-US">Amended and restated two thousand eight plan.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" xlink:label="loc_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">Nineteen Ninety Six Non Qualified Employee Stock Purchase Plan And Two Thousand Fifteen Non Qualified Stock Purchase Plan [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">1996 Non-Qualified Employee Stock Purchase Plan and 2015 Non-Qualified Stock Purchase Plan [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" xlink:to="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanAndTwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">Nineteen Ninety Six Non Qualified Employee Stock Purchase Plan And Two Thousand Fifteen Non Qualified Stock Purchase Plan [Member]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" xlink:label="loc_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" xml:lang="en-US">Nineteen Ninety Six Non Qualified Employee Stock Purchase Plan [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" xml:lang="en-US">1996 Non-Qualified Employee Stock Purchase Plan [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" xlink:to="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_NineteenNinetySixNonQualifiedEmployeeStockPurchasePlanMember" xml:lang="en-US">1996 non-qualified employee stock purchase plan.</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" xlink:label="loc_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">Two Thousand Fifteen Non Qualified Stock Purchase Plan [Member]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">2015 Non-Qualified Stock Purchase Plan [Member]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" xlink:to="lab_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_TwoThousandFifteenNonQualifiedStockPurchasePlanMember" xml:lang="en-US">Two Thousand Fifteen Non Qualified Stock Purchase Plan [Member]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AllocatedShareBasedCompensationExpense" xml:lang="en-US">Allocated Share-based Compensation Expense</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AllocatedShareBasedCompensationExpense" xml:lang="en-US">Stock-based compensation expense</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="lab_us-gaap_AllocatedShareBasedCompensationExpense" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xml:lang="en-US">Common Stock, Capital Shares Reserved for Future Issuance</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xml:lang="en-US">Common stock, reserved for issuance</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:to="lab_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xml:lang="en-US">Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xml:lang="en-US">Unrecognized compensation expense related to non-vested restricted stock, weighted-average period in years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xml:lang="en-US">Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xml:lang="en-US">Unrecognized compensation expense related to non-vested restricted shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" xlink:label="loc_us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" xml:lang="en-US">Proceeds and Excess Tax Benefit from Share-based Compensation</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" xml:lang="en-US">Cash proceeds received from the exercise of stock options</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" xlink:to="lab_us-gaap_ProceedsAndExcessTaxBenefitFromSharebasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period</label>
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<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted average grant-date fair value of restricted and deferred stock awards granted</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted Average Fair Value, Awarded</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xml:lang="en-US">Aggregate fair value of restricted and deferred stocks vested</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xml:lang="en-US">Vesting period of options, maximum years</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xml:lang="en-US">Shares available for future grants and awards under Stock Incentive Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xml:lang="en-US">Aggregate intrinsic value of stock options exercised</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xml:lang="en-US">Aggregate Intrinsic Value, Exercised</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xml:lang="en-US">Percentage of market value of common stock at which employees are permitted to purchase</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xml:lang="en-US">Stock Issued During Period, Shares, Employee Stock Purchase Plans</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xml:lang="en-US">Aggregate number Shares issued under Stock Purchase Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xml:lang="en-US">Share based compensation authorized shares</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xml:lang="en-US">Number of Shares, Forfeited</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted Average Fair Value, Forfeited</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xml:lang="en-US">Number of Shares, Awarded</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xml:lang="en-US">Number of Shares, Non-vested shares at January 1, 2019</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xml:lang="en-US">Number of Shares, Non-vested shares at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted Average Fair Value, Non-vested shares at January 1, 2019</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted Average Fair Value, Non-vested shares at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xml:lang="en-US">Number of Shares, Vested</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xml:lang="en-US">Weighted Average Fair Value, Vested</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xml:lang="en-US">Number of Shares, Exercisable at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xml:lang="en-US">Weighted Average Exercise Price, Exercisable at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xml:lang="en-US">Weighted Average Remaining Contractual Term (in years), Exercisable at December 31, 2019</label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xml:lang="en-US">Number of Shares, Outstanding at January 1, 2019</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xml:lang="en-US">Number of Shares, Outstanding at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xml:lang="en-US">Weighted Average Exercise Price, Outstanding at January 1, 2019</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xml:lang="en-US">Weighted Average Exercise Price, Outstanding at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xml:lang="en-US">Weighted Average Remaining Contractual Term (in years), Outstanding at December 31, 2019</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xml:lang="en-US">Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xml:lang="en-US">Weighted Average Exercise Price, Exercised</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xml:lang="en-US">Number of Shares, Exercised</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityAbstract" xlink:label="loc_us-gaap_EquityAbstract" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_EquityAbstract" xml:lang="en-US">Equity [Abstract]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityAbstract" xlink:to="lab_us-gaap_EquityAbstract" />
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CommonStockTable" xlink:label="loc_md_CommonStockTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CommonStockTable" xml:lang="en-US">Common Stock [Table]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CommonStockTable" xml:lang="en-US">Common Stock [Table]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CommonStockTable" xlink:to="lab_md_CommonStockTable" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CommonStockTable" xml:lang="en-US">Common Stock [Table]</label>
<loc xlink:type="locator" xlink:href="md-20191231.xsd#md_CommonStockLineItems" xlink:label="loc_md_CommonStockLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_md_CommonStockLineItems" xml:lang="en-US">Common Stock [Line Items]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_md_CommonStockLineItems" xml:lang="en-US">Common Stock [Line Items]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_md_CommonStockLineItems" xlink:to="lab_md_CommonStockLineItems" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="lab_md_CommonStockLineItems" xml:lang="en-US">Common Stock [Line Items]</label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xml:lang="en-US">Adjustments Related to Tax Withholding for Share-based Compensation</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xml:lang="en-US">Amount withheld to satisfy minimum statutory tax withholding obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:to="lab_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xml:lang="en-US">Shares Paid for Tax Withholding for Share Based Compensation</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xml:lang="en-US">Number of shares withheld to satisfy minimum statutory tax withholding obligations</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:to="lab_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xml:lang="en-US">Stock Repurchase Program, Authorized Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xml:lang="en-US">Common stock authorized for repurchase</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:to="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xml:lang="en-US">Stock Repurchase Program, Remaining Authorized Repurchase Amount</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xml:lang="en-US">Company's Common stock repurchased</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:to="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareRepurchaseProgramAxis" xml:lang="en-US">Share Repurchase Program [Axis]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareRepurchaseProgramAxis" xml:lang="en-US">Share Repurchase Program [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis" xlink:to="lab_us-gaap_ShareRepurchaseProgramAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_ShareRepurchaseProgramDomain" xml:lang="en-US">Share Repurchase Program [Domain]</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_ShareRepurchaseProgramDomain" xml:lang="en-US">Share Repurchase Program [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain" xlink:to="lab_us-gaap_ShareRepurchaseProgramDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SubsequentEventTypeAxis" xml:lang="en-US">Subsequent Event Type [Axis]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="lab_us-gaap_SubsequentEventTypeAxis" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_SubsequentEventTypeDomain" xml:lang="en-US">Subsequent Event Type [Domain]</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="lab_us-gaap_SubsequentEventTypeDomain" />
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized" />
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized" xml:lang="en-US">Defined Contribution Plan, Cost</label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized" xml:lang="en-US">Expense of retirement plans related to the 401(k) Plans</label>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanCostRecognized" xlink:to="lab_us-gaap_DefinedContributionPlanCostRecognized" />
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