1. National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology , Beijing , P.R. China
2. Beijing Engineering Research Center of Laboratory Medicine , Beijing , P.R. China
3. Institute of Geriatric Medicine, Chinese Academy of Medical Sciences , Beijing , P.R. China
4. Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , P.R. China
5. National Center for Clinical Laboratories, Beijing Hospital , Beijing , P.R. China