Author affiliations:
1 Department of Gastroenterology, Saitama Medical University International Medical Center, Saitama 350-1298, Japan
2 Department of Gastroenterology Medicine Center, Shonan Kamakura General Hospital, Kanagawa 247-8533, Japan
3 Department of General Internal Medicine, Shonan Kamakura General Hospital, Kanagawa 247-8533, Japan