1. Department of Nephrology, Nagano Red Cross Hospital, 5-22-1 Wakasato, Nagano 380-8582, Japan
2. Department of Nephrology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan
3. Graduate School of Health Sciences, Matsumoto University, 2095-1 Niimura, Matsumoto 390-1241, Japan