1. National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing Engineering Research Center of Laboratory Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
2. National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing Engineering Research Center of Laboratory Medicine, Beijing, P. R. China
3. Clinical Laboratory, Department, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China
4. The Ministry of Health Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, P. R. China