Shoko Ono1, Yuji Ono2, Naoya Sakamoto3. 1. Department of Gastroenterology, Hokkaido University Hospital, Sapporo, Japan. 2. Department of Gastroenterology, Sapporo City Hospital, Sapporo, Japan. 3. Department of Gastroenterology and Hepatology,, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan.