1. Graduate School of Life Science and Faculty of Advanced Life Science, Hokkaido University, N22, W11, Kita-ku, Sapporo 001-0021, Japan
2. Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan
3. Departments of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan
4. Department of Gastroenterological Surgery I, Graduate School of Medicine, Hokkaido University, N15, W7, Kita-ku, Sapporo 060-8638, Japan