1. Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
2. Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
3. McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri
4. Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri
5. Veterans Administration Saint Louis Health Care System, St. Louis, Missouri
6. Division of Pediatric Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri
7. Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri