1 Department Gastroenterology and Hepatology, Hakodate Municipal Hospital, Hakodate, Japan.
2 Department of Gastroenterology, Hakodate Municipal Hospital, Hakodate, Japan; Department of Gastroenterology and Hepatology, Hokkaido University Faculty of Medicine and Graduate School of Medicine, Sapporo, Japan.
3 Department of Gastroenterology, Hakodate Municipal Hospital, Hakodate, Japan.
4 Department of Gastroenterology and Hepatology, Hokkaido University Faculty of Medicine and Graduate School of Medicine, Sapporo, Japan.