Koji Kubota1, Akira Shimizu2, Yuji Soejima1. 1. Division of Gastroenterological, Hepato-Biliary-Pancreatic, Transplantation and Pediatric Surgery, Department of Surgery, Shinshu University School of Medicine, Nagano, 390-8621, Japan. 2. Division of Gastroenterological, Hepato-Biliary-Pancreatic, Transplantation and Pediatric Surgery, Department of Surgery, Shinshu University School of Medicine, Nagano, 390-8621, Japan. ashimizu@shinshu-u.ac.jp.