1. Division of Gastroenterology and Hepatology; Department of Internal Medicine; Toho University Medical Center; Omori Hospital, 6-11-1, Omorinishi Ota-ku Tokyo 143-8541 Japan
2. Department of Surgery; Toho University Medical Center; Omori Hospital, 6-11-1, Omorinishi Ota-ku Tokyo 143-8541 Japan