1. University of Colorado Denver, Aurora, CO, USA
2. Duke University Medical Center, Durham, NC, USA
3. Vanderbilt University Medical Center, Nashville, TN, USA
4. University of Pittsburgh Medical Center, Pittsburgh, PA, USA
5. University of Toronto, Toronto, Ontario, Canada
6. University of Florida, Gainesville, FL, USA
7. University of Western Ontario, London, Ontario, Canada
8. Mayo Clinic, Jacksonville, FL, USA