1. Department of Gastroenterology and Neurology, Faculty of Medicine, Kagawa University, Kita 761-0793, Kagawa, Japan
2. Department of General Internal Medicine, Faculty of Medicine, Kagawa University, Kita 761-0793, Kagawa, Japan
3. Department of Gastroenterological Surgery, Faculty of Medicine, Kagawa University, Kita 761-0793, Kagawa, Japan