1. Washington University School of Medicine (P.E.C.), St. Louis, Missouri 63110
2. Massachusetts General Hospital and Harvard Medical School (L.A.), Boston, Massachusetts 02114
3. Barts and the London School of Medicine, Queen Mary University of London (A.B.G.), London E1 2AD, United Kingdom
4. University of Sheffield (S.R.H.), Sheffield S10 2TN, United Kingdom
5. Mayo Clinic (V.M.M., F.J.S.), Rochester, Minnesota 55905
6. University of Minnesota (E.R.S.), Minneapolis, Minnesota 55455