1. The Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
2. Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Chiba 272-8516, Japan
3. Department of Medicine, Division of Gastroenterology, Showa University School of Medicine, Tokyo 142-8555, Japan
4. Department of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, Chiba 260-8670, Japan