Yi-Lei Mao, MD, PhD, Professor of Surgery, De- partment of Liver Surgery, Peking Union Medical College Hospital, Chi- nese Academy of Medical Sciences and Peking Union Medical College, 1# Shuaifuyuan, Wangfujing, Beijing 100730, China (Tel: +86-10-69156042; Fax: +86-10-69156043; Email: yileimao@126.com)