1. Department of Hematology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Bejing, China
2. Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
3. Peking University China-Japan Friendship School of Clinical Medicine, Bejing, China
4. Department of Urology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Bejing, China