1. From the Department of Pediatrics, Dartmouth/Hitchcock Medical Center, Lebanon, New Hampshire;
2. Department of Pediatrics, University of Iowa School of Medicine, Iowa City, Iowa;
3. University of Alabama Birmingham, School of Medicine, Birmingham, Alabama;
4. Department of Pediatrics, University of California, San Diego, La Jolla, California; and
5. Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington.