1. Department of Gastroenterology and Neurology, Faculty of Medicine, Kagawa University, Takamatsu 761-0793, Japan
2. Department of General Internal Medicine, Faculty of Medicine, Kagawa University, Takamatsu 761-0793, Japan
3. Division of Gastroenterology and Nephrology, Faculty of Medicine, Tottori University, Tottori 683-8504, Japan