1. Department of Gynecology and Obstetrics; Key Laboratory of Obstetrics and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second Hospital, Sichuan University; Chengdu Sichuan 610041 P. R. China
2. Department of Orthopedics, West China Hospital; Sichuan University; Chengdu Sichuan 610041 P. R. China
3. Department of Emergency Medicine; Thomas Jefferson University Hospital; Philadelphia PA 19107
4. Department of Surgery, Emergency Medicine; Kaiser Santa Clara Medical Center, Affiliate of Stanford University; Stanford CA 94305
5. The State Key Laboratory of Biotherapy; West China Hospital, Sichuan University; Chengdu Sichuan 610041 P. R. China
6. College of Biological Sciences; Sichuan University; Chengdu Sichuan 610041 P. R. China