1. University of California, Los Angeles, CA, USA
2. George Washington University School of Medicine, Washington, DC, USA
3. University of Pennsylvania, Philadelphia, PA, USA
4. Florida Kidney Physicians, Boca Raton, FL, USA
5. Duke University Medical Center, Durham, NC, USA
6. Southwest Kidney Institute, Phoenix, AZ, USA
7. University of North Carolina Kidney Center, Chapel Hill, NC, USA and the WG (Bill) Hefner Salisbury VA Medical Center, Salisbury, NC, USA
8. Stanford University School of Medicine, Stanford, CA, USA