1. Gastroenterology Division, National Hospital Organization Yokohama Medical Center, 3-60-2 Harajyuku, Totsuka-ku, Yokohama 245-8575, Japan
2. Nagai Clinic, 1-7-25 Yokodai, Isogo-ku, Yokohama 235-0045, Japan
3. Department of Gastroenterology and Hepatology, Yokohama City University Hospital, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
4. OkaMedical, 1-19-18-3F Kamiookanishi, Kounan-ku, Yokohama 233-0002, Japan
5. Sanno Hospital, 8-10-16 Akasaka, Minato-ku, Tokyo 107-0052, Japan