1. Department of Gastroenterology and Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan
2. Department of Gastroenterology, Tokai University Hospital, Iseahara, Japan
3. Department of Gastroenterology, Kameda Medical Center, Kamogawa, Japan
4. Department of Internal Medicine, Niigata Prefectural Shibata Hospital, Shibara, Japan
5. Department of Internal Medicine, Niigata Cancer Center Hospital, Niigata, Japan
6. Department of Gastroenterology and Hepatology, St. Marianna University School of Medicine, Kawasaki, Japan