1. Central Laboratory, Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, P. R. China
2. Department of Surgery, Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, P. R. China
3. Haici Hospital of Qingdao, 4 Renmin Road, Qingdao 266033, P. R. China
4. Department of Rheumatism and Immunology, Affiliated Hospital of Qingdao University Medical College, 16 Jiangsu Road, Qingdao 266003, P. R. China