1. Department of Gastroenterology and Nephrology, Chiba University, Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8677, Japan
2. Department of General Surgery, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8677, Japan
3. Department of Reproductive Medicine, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8677, Japan
4. Department of Emergency and Critical Care Medicine, Chiba University, Graduate School of Medicine, Chuo-ku, Chiba 260-8677, Japan