1. University of Alabama at Birmingham Birmingham AL USA
2. Duke University Medical Center Durham NC USA
3. Baylor College of Medicine Houston TX USA
4. Allegheny General Hospital Pittsburgh PA USA
5. Massachusetts General Hospital Boston MA USA
6. Columbia Presbyterian Medical Center New York NY USA
7. David Geffen UCLA School of Medicine, Greater Los Angeles VA Healthcare System Los Angeles CA USA
8. University of Rochester Medical Center Rochester NY USA
9. United Therapeutics Corp. Research Triangle Park NC USA
10. UCSD Medical Center San Diego CA USA