1. Department of Gastroenterology and Hepatology, Uonuma Institute of Community Medicine Niigata University Hospital, Japan
2. Department of Internal Medicine, Niigata Cancer Center Hospital, Japan
3. Department of Pathology, Uonuma Institute of Community Medicine Niigata University Hospital, Japan
4. Division of Gastroenterology and Hepatology, Graduate School of Medical and Dental Sciences, Niigata University, Japan