1. From the Department of General Pediatrics and Adolescent Medicine, Children's National Medical Center, Washington, District of Columbia; the
2. Children's Research Institute, Washington, District of Columbia; the
3. George Washington University School of Medicine, Washington, District of Columbia; the
4. National Institutes of Child Health and Human Development, Bethesda, Maryland.
5. Department of Emergency Medicine, Children's National Medical Center, Washington, District of Columbia; and the