1. Department of Gastroenterology, Okayama University Hospital, Okayama, Japan
2. Department of Internal Medicine, Hiroshima City Hospital, Hiroshima, Japan
3. Department of Gastroenterology, Mitoyo General Hospital, Kagawa, Japan
4. Department of Otolaryngology-Head & Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan