1. Department of Urology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8577, Japan
2. International Medical Center, University of Tsukuba Affiliated Hospital, Tsukuba, Ibaraki 305‑8576, Japan
3. Department of Urology, Ibaraki Prefectural Central Hospital, Kasama, Ibaraki 309‑1793, Japan
4. Life Science Research Center, Technology Research Laboratory, Shimadzu Corporation, Kyoto 604‑8511, Japan
5. Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8575, Japan