1. University of Texas Southwestern Medical Center at DallasDallasTXUSA
2. Penn Presbyterian Medical CenterPhiladelphiaPAUSA
3. Winthrop University HospitalMineolaNYUSA
4. Harbor UCLA Medical CenterTorranceCAUSA
5. University of Colorado HealthDenverCOUSA
6. University of CaliforniaSan DiegoLa JollaCAUSA