Objective To screen the stable high-producing strains carrying anti-nasopharyngeal carcinoma(NPC)plasmid pFY.Methods Competent E.coli JM109 was prepared by the CaCl2 method and transformed with anti-NPC plasmid pFY.The bacterial colonies obtained from the agar plate were screened for selecting the single colony conforming to the standards as the bac-terial strain and conducting the stability test.The plasmid content was detected by the plasmid extraction reagent kit.Anti-NPC plasmid pFY was transfected into nasopharynegal carcinoma cell line CNE-2.The influence of transfection reagent and the plasmid vector on the cell proliferation was detected by MTT.Results The DNA concentration of plasmids in the culture solution of bacte-rial strain obtained by screening was 30 mg/mL.The proportion of supercoiled DNA was 92%.The identification of electrophoresis and restriction enzymes showed that the plasmids harbored in the 50th progeny of this strain were same as those in the primary. Plasmid pFY had the evident inhibiting effect on the growth of CNE-3 cell line.Conclusion The stable high-producing strains of E. coli carrying anti-NPC plasmid pFY is successfully screened out,which lays the foundation for large-scale preparation of plasmid pFY for clinical utility.

Objective To study the preventive effect and mechanism of aesculin on intestinal mucosa in rats with experimental ulcerative colitis (UC) . Methods Forty specific-pathogen free SD rats were randomly divided into normal group, model group, salicylazosulfapyridine (SASP, 600 mg/kg) group and aesculin (EH, 100 mg/kg) group, 10 in each group. Rats in model group, SASP group and EH group were given enema with trinitrobenzene sulfonic acid ( TNBS, 100 mg/kg) for the establishment of UC model. The rats in SASP group and EH group were given gastric gavage of SASP and aesculin respectively. At the end of experiment, the serum levels of tumor necrosis factor alpha ( TNF-α) and interleukin 10 ( IL-10) were detected by enzyme-linked immunosorbent assay (ELISA) . The general state, histological features of intestinal mucosa and serum TNF-αand IL-10 levels of rats in each group were compared. Results Aesculin significantly improved the general state and relieved the inflammation of the colonic mucosa of UC rats. The disease activity index ( DAI) scores and tissue damage index (TDI) scores in the model group were significantly higher than those in the normal group ( P<0.01) . The DAI scores and TDI scores in the medication groups were significantly lower than those in the model group (P<0.01) . The serum TNF-αlevel was significantly higher and IL-10 level was significantly lower in the model group than the normal group ( P<0.01) . After treatment, TNF-α was decreased and IL-10 was increased in SASP group and EH group as compared with the model group (P<0.01) . Conclusion Aesculin has certain therapeutic effect on TNBS-induced UC in rats through significantly relieving the symptoms of UC rats. The mechanism may be related with the inhibition of TNF-α secretion and the increase of IL-10 expression, and then improving the disorder of intestinal immune function.