1. Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan
2. Division of Nephrology, Shimoochiai Clinic, Tokyo, Japan
3. Tsuruta Itabashi Clinic, Tokyo, Japan
4. Gastroenterology Center, Ehime Prefectural Central Hospital, Matsuyama, Japan
5. Center of Gastroenterology, Teine Keijinkai Hospital, Sapporo, Japan
6. Department of Epidemiology, Infectious Disease Control, and Prevention, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan