1. Department of Gastroenterology, National Hospital Organization Fukuyama Medical Center, 4-14-17, Okinogamicho, Fukuyama-shi, Hiroshima 720-8520, Japan
2. Advanced Emergency and Critical Care Medical Center, Okayama University Hospital, 2-5-1 Kita-ku, Shikata-cho, Okayama-shi, Okayama 700-8558, Japan