1. Department of Internal Medicine, Division of Gastroenterology; Showa University, School of Medicine; Tokyo Japan
2. Department of Gastroenterology; St Luke's International Hospital; Tokyo Japan
3. Division of Gastroenterology; Showa University Fujigaoka Hospital; Yokohama Japan
4. Department of Internal Medicine, Division of Gastroenterology and Hepatology; The Jikei University School of Medicine; Tokyo Japan