1. Department of General Medicine; National Hospital Organization Shibukawa Medical Center; 383 Shiroi Shibukawa Gunma 377-0280 Japan
2. Department of Internal Medicine; Japan Community Health Care Organization Gunma Chuo Hospital; 1-7-13 Koun-cho Maebashi Gunma 371-0025 Japan
3. Department of Medicine and Biological Science; Gunma University Graduate School of Medicine; 3-39-22 Showa-machi Maebashi Gunma 371-8511 Japan