1. Department of Gastroenterology, Aso Iizuka Hospital, Iizuka, 820-8505 Japan
2. Department of Pathology, Aso Iizuka Hospital, Iizuka, 820-8505 Japan
3. Clinical Research Support Office, Aso Iizuka Hospital, Iizuka, 820-8505 Japan
4. Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan