1. Division of Gastroenterology, Tsukuba Memorial Hospital, Ibaraki, Japan
2. Division of Rehabilitation, Tsukuba Memorial Hospital, Ibaraki, Japan
3. Division of Endoscopy, Tsukuba Memorial Hospital, Ibaraki, Japan
4. Sugiyama Clinic of Internal Medicine and Dermatology, Ibaraki, Japan
5. Faculty of Medicine, University of Tsukuba, Ibaraki, Japan