1. Gastroenterology Center, Ehime Prefectural Central Hospital, Kasugamachi 83, Matsuyama, Ehime 790-0024, Japan
2. Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon 791-0295, Japan
3. Department of Internal Medicine, Saiseikai Imabari Hospital, Imabari 794-0054, Japan