1. Nemours Children's Clinic (L.T.-S., M.T., N.M.), Jacksonville, Florida 32207;
2. University of Florida (L.T.-S.), Jacksonville, Florida 32209;
3. Institute of Maternal and Child Research (V.M.), University of Chile, Santiago 1058, Chile;
4. Nemours Children's Clinic (M.T.), Orlando, Florida 32806;
5. University of California, San Diego (K.O.K.), San Diego, California 92093;
6. Mayo Clinic (R.S.), Rochester, Minnesota 55905;
7. DuPont Hospital for Children (J.H.), Wilmington, Delaware 19803;
8. University of Virginia Medical Center (R.J.S.), Charlottesville, Virginia 22903;
9. Jefferson Medical Center (J.L.R.), Philadelphia, Pennsylvania 19107