To investigate the effects ofS-Adenosylmethionine(SAM)on liver injury induced by carbon tetrachloride(CCl4)in mice,In this study,60 C57BL/6 mice were randomly divided into CON group,CCl4 group,low dose group(CCl4+SAM-L,50 mg/kg SAM),medium dose group(CCl4+SAM-M,100 mg/kg)and high dose group(CCl4+SAM-M,200 mg/kg).Except CON group,mice in other groups were intraperitoneally injected with CCl4(10 mL/kg,0.2％),and mice in CON group were injected with equal volume olive oil,3 times a week for 4 weeks,to establish mouse liver injury model.At the same time,mice in low,medium and high dose groups were given 100 μL SAM,CON group and CCl4 group were given equal volume PBS for 4 weeks.The results showed that CCl4 promoted liver fibrosis and increased serum ALT,AST and TBIL levels(P＜0.05).Different doses of SAM significantly alleviated liver fibrosis injury and decreased serum ALT,AST and TBIL levels(P＜0.05).Compared with CON group,CCl4 significantly decreased the liver T-AOC,SOD,CAT and GSH-Px levels(P＜0.05),and increased the liver MDA level(P＜0.05).Compared with CCl4 group,the levels of T-AOC,SOD,CAT and GSH-PX in liver of mice in CCl4+SAM group were significantly increased(P＜0.05),while the level of MDA was significantly decreased(P＜0.05).Compared with CON group,liver levels of IL-6,IL-1β and TNF-α in CCl4 group were significantly increased(P＜0.05).Compared with CCl4 group,different doses of SAM could significantly reduce the levels of IL-6,IL-1β and TNF-α in liver of mice(P＜0.05).Compared with CON group,the expressions of Nrf2,NQO-1 and HO-1 genes in liver of CCl4 group were decreased(P＞0.05),while the expression of Keap1 gene was significantly increased(P＞0.05).Compared with CCl4 group,medium and high doses of SAM significantly increased the expressions of Nrf2,NQO-1 and HO-1 genes in liver of mice(P＜0.05),and decreased the expres-sion of Keap1 gene(P＞0.05).Compared with CON group,the contents of acetic acid,propionic acid and butyric acid in cecum of CCl4 group were significantly decreased(P＜0.05).Compared with CCl4 group,the contents of propionic acid and butyric acid in high-dose SAM group were sig-nificantly increased(P＜0.05).Microbial analysis showed that CCl4 significantly decreased the rel-ative abundance of Akkermansia and Prevotellaceae_NK3B31_group(P＜0.05),and changed the composition of intestinal microorganisms.These results indicate that SAM regulates the gene ex-pression of Nrf2 antioxidant signaling pathway to a certain extent,increases intestinal SCFAs con-tent,regulates intestinal microbial structure,and thus alleviates liver injury,oxidative stress and inflammation caused by CCl4.This study provides reference and theoretical basis for SAM in the treatment and remission of drug-induced liver injury.

To investigate the effects ofS-Adenosylmethionine(SAM)on liver injury induced by carbon tetrachloride(CCl4)in mice,In this study,60 C57BL/6 mice were randomly divided into CON group,CCl4 group,low dose group(CCl4+SAM-L,50 mg/kg SAM),medium dose group(CCl4+SAM-M,100 mg/kg)and high dose group(CCl4+SAM-M,200 mg/kg).Except CON group,mice in other groups were intraperitoneally injected with CCl4(10 mL/kg,0.2％),and mice in CON group were injected with equal volume olive oil,3 times a week for 4 weeks,to establish mouse liver injury model.At the same time,mice in low,medium and high dose groups were given 100 μL SAM,CON group and CCl4 group were given equal volume PBS for 4 weeks.The results showed that CCl4 promoted liver fibrosis and increased serum ALT,AST and TBIL levels(P＜0.05).Different doses of SAM significantly alleviated liver fibrosis injury and decreased serum ALT,AST and TBIL levels(P＜0.05).Compared with CON group,CCl4 significantly decreased the liver T-AOC,SOD,CAT and GSH-Px levels(P＜0.05),and increased the liver MDA level(P＜0.05).Compared with CCl4 group,the levels of T-AOC,SOD,CAT and GSH-PX in liver of mice in CCl4+SAM group were significantly increased(P＜0.05),while the level of MDA was significantly decreased(P＜0.05).Compared with CON group,liver levels of IL-6,IL-1β and TNF-α in CCl4 group were significantly increased(P＜0.05).Compared with CCl4 group,different doses of SAM could significantly reduce the levels of IL-6,IL-1β and TNF-α in liver of mice(P＜0.05).Compared with CON group,the expressions of Nrf2,NQO-1 and HO-1 genes in liver of CCl4 group were decreased(P＞0.05),while the expression of Keap1 gene was significantly increased(P＞0.05).Compared with CCl4 group,medium and high doses of SAM significantly increased the expressions of Nrf2,NQO-1 and HO-1 genes in liver of mice(P＜0.05),and decreased the expres-sion of Keap1 gene(P＞0.05).Compared with CON group,the contents of acetic acid,propionic acid and butyric acid in cecum of CCl4 group were significantly decreased(P＜0.05).Compared with CCl4 group,the contents of propionic acid and butyric acid in high-dose SAM group were sig-nificantly increased(P＜0.05).Microbial analysis showed that CCl4 significantly decreased the rel-ative abundance of Akkermansia and Prevotellaceae_NK3B31_group(P＜0.05),and changed the composition of intestinal microorganisms.These results indicate that SAM regulates the gene ex-pression of Nrf2 antioxidant signaling pathway to a certain extent,increases intestinal SCFAs con-tent,regulates intestinal microbial structure,and thus alleviates liver injury,oxidative stress and inflammation caused by CCl4.This study provides reference and theoretical basis for SAM in the treatment and remission of drug-induced liver injury.

Questionnaire survey and semi-structured interview were done in December 2005 and April 2006 to explore the reasons why foreign and minority medical students failed in course examinations last year.It is found that many factors affect their studying such as proficiency in Chinese,original foundation,studying and living habits,familiarity to the regulations of educational affairs,time and effort spent for self-studying and the attitude in which the teachers treat them.And also the correspondent countermeasures are given according to the survey and interview.