1. Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan
2. Department of Gastroenterology, Wakayama Rousai Hospital, Wakayama, Japan
3. Clinical Support Center, Wakayama Medical University, Wakayama, Japan
4. Department of Gastroenterology, National Hospital Organization Minami Wakayama Medical Center, Wakayama, Japan
5. Department of Endoscopy, Kishiwada Tokushukai Hospital, Kishiwada, Japan.