1 First Department of Internal Medicine, Faculty of Medicine, University of Yamanashi, 1110, Shimokato, Chuo, Yamanashi, 409-3898, Japan. maekawa@yamanashi.ac.jp.
2 First Department of Internal Medicine, Faculty of Medicine, University of Yamanashi, 1110, Shimokato, Chuo, Yamanashi, 409-3898, Japan.