1. Departments of Environmental and Preventive Medicine; Oita University Faculty of Medicine; Yufu-City Oita Japan
2. Departments of General Medicine; Oita University Faculty of Medicine; Yufu-City Oita Japan
3. Departments of Gastroenterology; Oita University Faculty of Medicine; Yufu-City Oita Japan
4. Department of Endoscopy; University Hospital; University of the Ryukyus; Nishihara Okinawa Japan
5. Department of Medicine-Gastroenterology; Baylor College of Medicine and Michael E. Debakey Veterans Affairs Medical Center; Houston Texas USA