| Nanjing, China 
 Author Affiliations: Research Institute of General Surgery, Nanjing General Hospital of Nanjing Military Command, PLA, Nanjing 210002, China (Li N)
 Corresponding Author: Ning Li, MD, Research Institute of General Surgery, Nanjing General Hospital of Nanjing Military Command, PLA, Nanjing 210002, China (Tel: 86-25-80860089; Email: liningrigs@vip.sina.com)
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