1. Division of Gastroenterology and Hepatology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
2. Division of Gastroenterology and Hepatology, Saiseikai Niigata Daini Hospital, Niigata, Japan
3. Division of Gastroenterology and Hepatology, Nagaoka Red Cross Hospital, Niigata, Japan
4. Department of Gastroenterology, Niigata Prefectural Yoshida Hospital, Niigata, Japan
5. Division of Gastroenterology and Hepatology, Niigata Cancer Center Hospital, Niigata, Japan