1. Division of Gastroenterology; Tohoku University Graduate School of Medicine; Sendai Japan
2. Department of Gastroenterology; Akita University Graduate School of Medicine; Akita Japan
3. Department of Gastroenterology; Yamagata University Faculty of Medicine; Yamagata Japan
4. Department of Gastroenterology; South Miyagi Medical Center; Shibata-gun Japan
5. Department of Gastroenterology; Osaki Citizen Hospital; Osaki Japan