1. Department of Internal Medicine, Jiaozhou Central Hospital, Qingdao, Shandong 266300, P.R. China
2. Department of Cardiothoracic Surgery, Shanxian Dongda Hospital, Heze, Shandong 274300, P.R. China
3. Department of Laboratory Medicine, Heze Hospital of Traditional Chinese Medicine, Heze, Shandong 274000, P.R. China
4. Department of General Surgery, 80th Army Hospital, Weifang, Shandong 261021, P.R. China