1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Kawasaki Municipal Tama Hospital
2. Division of Gastroenterology, Department of Internal Medicine, St. Marianna University School of Medicine, Yokohama City Seibu Hospital
3. Division of Gastroenterology and Hepatology, Department of Internal Medicine, St. Marianna University School of Medicine
4. Division of Infectious Diseases, Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo