1. Department of Respiratory Medicine and Intensive Care Unit, Binzhou Medical University Hospital, Binzhou, Shandong 256603, P.R. China
2. Department of Cell Biology, Binzhou Medical University, Yantai, Shandong 264003, P.R. China
3. Department of Clinical Laboratory, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong 264003, P.R. China