1. Department of Gastroenterology, National Hospital Organization Yokohama Medical Center, Yokohama, Japan
2. Department of Gastroenterology and Hepatology, Yokohama City University School of Medicine, Yokohama, Japan
3. Department of Medical Education, Yokohama City University School of Medicine, Yokohama, Japan
4. Department of Anesthesiology, Yokohama City University School of Medicine, Yokohama, Japan
5. Office of Postgraduate Medical Education, Yokohama City University Hospital, Yokohama, Japan