1 Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, 1-847, Amanuma, Omiya-ku, Saitama 330-8503, Japan.
2 Division of Cardiology, Nephrology, Pulmonology and Neurology, Department of Internal Medicine, Asahikawa Medical University, 2-1-1-1 Midorigaoka Higashi, Asahikawa 078-8510, Japan.