1. University of Iowa Children's Hospital; Iowa city, Iowa
2. Cincinnati Children's Hospital Medical Center; Cincinnati, Ohio
3. St. Louis University; St. Louis, Missouri
4. Polish Mother's Memorial Hospital, Research Institute; Lodz Poland
5. University of Utah; Salt Lake City, Utah
6. LeBonheur Children's Hospital; Memphis, Tennessee
7. Wake Forest Baptist Medical Center; Winston-Salem, North Carolina
8. University of Michigan; Ann Arbor, Michigan