1 Department of General Internal Medicine, Aizu Medical Center, Fukushima Medical University, Fukushima, 21-2. Maeda, Tanisawa, Kawahigashi-machi, Aizuwakamatsu-shi, Fukushima 969-3492, Japan.
2 Department of General Internal Medicine, Aizu Medical Center, Fukushima Medical University, Fukushima, 21-2. Maeda, Tanisawa, Kawahigashi-machi, Aizuwakamatsu-shi, Fukushima 969-3492, Japan and Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata city, Niigata 951-8510, Japan.