1. Department of Gastroenterology and Hepatology; Graduate School of Tokyo Medical and Dental University; Tokyo; Japan
2. Colo-Proctology Center Matsushima Clinic; Kanagawa; Japan
3. Sameshima Hospital; Kagoshima; Japan
4. Ieda Hospital; Aichi; Japan
5. Division of Lower Gastroenterology; Department of Internal Medicine; Hyogo College of Medicine; Hyogo; Japan
6. Division of Gastroenterology and Hepatology; Department of Internal Medicine; School of Medicine; Keio University; Tokyo; Japan