1. Department of Microbiology, School of Medicine; Chiba University; Chiba Chiba 260 Japan
2. Department of Internal Medicine, School of Medicine; Chiba University; Chiba Chiba 260 Japan
3. Department of Obstetrics and Gynecology, School of Medicine; Chiba University; Chiba Chiba 260 Japan
4. Department of Anatomy, School of Medicine; Chiba University; Chiba Chiba 260 Japan