1. Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke City, Tochigi, Japan;
2. Division of Nephrology, Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Omiya, Saitama City, Saitama, Japan;
3. Department of Medical Physiology, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan