ABSTRACT
Objective To investigate the role of N-acetylcysteine as a protective agent in rifampicin-induced hepatic injury of mice. Methods Thirth-two Kunming mice were randomly divided into four groups(n=8 each).The mice in each group were injected intraperitoneally with 0.9% sodium chloride solution (control), N-acetylcysteine (NAC), combination of rifampicin (R), or NAC and R (NAC+R) once every day.After 14 days, the liver index (LI), alanine aminotransferase (ALT) and aspartate aminotransferase ( AST) activity in serum, and the level of malondialdehyde( MDA) ,superoxide dismutase( SOD) activity in liver tissues were measured respectively.Hepatic tissue morphology was observed under light microscope. Results Macroscopic analysis revealed that rifampicin led to severe liver tissue injury,including a wide range of hepatocellular vascular congestion,fatty change and local necrosis, whereas the administrationof NAC produced a significant reduction of rifampicin-induced hepatotoxicity .LI,ALT and AST activities in R or NAC+R group were significantly elevated as compared with the control group(P<0.01) .LI, activities of ALT and AST in serum,and MDA levels in liver tissues in NAC+R group were significantly lower than those in R group ( P<0.01) ,but the SOD activity in NAC+R group was increased significantly in comparison with R group (P<0.01). Conclusion Rifampicin was able to cause severe hepatic injury.Pre-administration of NAC reduced the side-effect induced by the treatment with the rifampicin.
ABSTRACT
To produce the reverse transcriptase of moloney murine leukemia virus (MMLV-RT) through gene recombination, MMLV-rt gene was amplified by polymerase chain reaction (PCR) with specifically designed primers bearing restriction enzyme sites. Five mutation sites increasing the solution of the target protein were introduced through Site-directed mutation. After verification by sequencing, the gene was cloned into the expression vector pET15b to construct the recombinant plasmid pET15b-MMLV-rt. Purified MMLV-RT was obtained by affinity chromatography (Ni3+-NTA beads). Molecular weight and purity of MMLV-RT were analyzed with SDS-PAGE. Enzyme activity was characterized with RT-PCR. We successfully constructed the recombinant plasmid pET15b-MMLV-rt and obtained the MMLV-RT fusion protein with 6His on the N-terminus. Recombinant protein was purified through Ni3+-NTA beads based affinity chromatography, the purity of which was 96%. The Activity of the enzyme was high. MMLV-RT of 96% purity was obtained with the prokaryotic expression technique, which serves as the basis for mass production of this enzyme.