1. Department of General Medicine, Kyushu University, Fukuoka 812-8582, Japan.
2. Department of Clinical Research, Hara-Doi Hospital, Fukuoka 813-8588, Japan.
3. National Kyushu Medical Center, Fukuoka 810-0065, Japan.
4. Department of General Medicine, Kyushu University, Fukuoka 812-8582, Japan; Department of Environmental Medicine and Infectious Diseases, Faculty of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.