1. International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai JiaoTong University, 910 Hengshan Road, Shanghai 200030, P. R. China
2. Department of General Surgery, The First Affiliated Hospital of University of Science and Technology, 17 LuJiang Road, LuYang District, HeFei 230031, P. R. China
3. Harbin Center for Disease Control and Prevention, 30 WeiXing Road, DaoWai District, Harbin 150056, P. R. China
4. Department of Clinical Laboratory, The Fourth Affiliated Hospital of Harbin Medical University, 37 YiYuan Street, NanGang District, Harbin 150001, P. R. China