1. Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, Japan
2. Department of Gastroenterology, Nayoro City General Hospital, Japan
3. Department of Gastroenterology, Hokkaido Prefectural Welfare Federation of Agricultural Cooperative Asahikawa Kosei General Hospital, Japan
4. Gastroenterology Medicine Center, Shonan Kamakura General Hospital, Japan
5. Center for Clinical and Biomedical Research, Sapporo Higashi Tokushukai Hospital, Japan