1. Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami Kogushi, Ube, Yamaguchi 755-8505, Japan
2. Graduate School of Health and Welfare, Yamaguchi Prefectural University, Yamaguchi 753-8502, Japan
3. Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka 830-0011, Japan