1. Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (C.M.D., A.L.C., K.A.F.)
2. University of Cape Town, Cape Town, South Africa (L.B., L.M., R.W.)
3. Massachusetts General Hospital, Boston, Massachusetts (M.E.S.)
4. Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts (P.E.S.)
5. Columbia University, New York, New York (E.J.A.)
6. Massachusetts General Hospital, Harvard Medical School, and Brigham and Women's Hospital, Boston, Massachusetts (R.P.W.)