1. Division of Gastroenterology; Department of Internal Medicine; Keio University School of Medicine; Tokyo; Japan
2. Department of Pathology; Keio University School of Medicine; Tokyo; Japan
3. Department of Physiology; Keio University School of Medicine; Tokyo; Japan
4. Department of Digestive Surgery and Transplantation Surgery; Tokyo Medical University Hachioji Medical Center; Tokyo; Japan
5. Department of Surgery; Kawasaki Municipal Hospital; Kanagawa; Japan
6. Department of Surgery; Keio University School of Medicine; Tokyo; Japan