Seshiru Nakazawa1, Toshiki Yajima2, Ken Shirabe1. 1. Department of General Surgical Science, Gunma University, Graduate School of Medicine, Maebashi, Japan. 2. Department of General Surgical Science, Gunma University, Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi 371-8511, Japan. Electronic address: yajimato@gunma-u.ac.jp.