Department of Internal Medicine, Keiyu Hospital, Yokohama, Japan. amizuki2@yahoo.co.jp. Department of Preventive Medicine, Tokai University School of Medicine, Isehara, Japan. Department of Internal Medicine, Saiseikai Central Hospital, Tokyo, Japan. Department of Internal Medicine, Keiyu Hospital, Yokohama, Japan. Department of Gastroenterology and Hepatology, Shimane University School of Medicine, Izumo, Japan.