1. Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky
2. Research Triangle Institute International, Research Triangle Park, North Carolina
3. Department of Pediatrics, University of Miami School of Medicine, Miami, Florida
4. Department of Pediatrics, Wayne State University School of Medicine, Detroit, Michigan
5. Department of Pediatrics, Brown University Medical School, Providence, Rhode Island
6. National Institute of Child Health and Human Development, Bethesda, Maryland