1. Columbia University Vagelos College of Physicians and Surgeons and New York-Presbyterian HospitalNew York, New York
2. San Francisco General Hospital and University of California, San FranciscoSan Francisco, California
3. Massachusetts General HospitalBoston, Massachusetts
4. University of CincinnatiCincinnati, Ohio
5. New York-Presbyterian HospitalNew York, New Yorkand
6. Hospital of the University of PennsylvaniaPhiladelphia, Pennsylvania