1. Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
2. Department of Gastroenterology, Clinical Research Institute, National Hospital Organization, Kyushu Medical Center, Fukuoka, Japan
3. Department of Gastroenterology, Harasanshin Hospital, Fukuoka, Japan
4. Department of Gastroenterology, Kitakyushu Municipal Medical Center, Fukuoka, Japan