1 Department of Gastroenterology, Tokyo Dental College, Ichikawa General Hospital, 5-11-13, Sugano, Ichikawa, Chiba, 272-8513, Japan. kenakamura@tdc.ac.jp.
2 Department of Gastroenterology, St. Luke's International Hospital, Tokyo, Japan. kenakamura@tdc.ac.jp.
3 Department of Pathology, St. Luke's International Hospital, Tokyo, Japan.
4 Department of Gastroenterology, St. Luke's International Hospital, Tokyo, Japan.