Detection of binding activity and biologic effect of a novel alpha-melanocyte-stimulating hormone analogue / 药学学报

Binding activity and biologic effect of a novel alpha-melanocyte-stimulating hormone analogue were tested on cells transiently expressing the human melanocortin-1 (MC1), MC3, MC4, and MC5 receptors. The human MC1 and MC5 receptor genes were cloned into the expression vector pcDNA3. 1/ myc-his(-) B. The vectors were transferred to HEK-293 cells by the calcium phosphate method. Stable receptor populations were generated using G418 selection (900 microg x mL(-1)) for subsequent bioassay analysis. K(i) values of the novel alpha-MSH analogue for MC1, MC3, MC4, and MC5 receptors were obtained in competition with [125I]-NDP-MSH for binding studies. The cyclic AMP level was tested by using [3H]-cyclic AMP kit. It is showed that K(i) values of the novel alpha-MSH analogue for MC1, MC3, MC4, and MC5 receptors were (0.159 +/- 0.040), (35.430 +/- 6.743), (19.293 +/- 2.780) and (2.230 +/- 0.670) nmol L(-1), respectively. Its EC50 values for MC1, MC3, MC4, and MC5 receptors were (0.45 +/- 0.07), (7.80 +/- 0.65), (2.55 +/- 0.23) and (0.33 +/- 0.09) nmol L(-1), respectively. In these tests, the novel alpha-MSH analogue is a MC1R and MC5R selective agonist.

The analysis of plasmid-mediated AmpC enzyme genotype and epidemiology of Escherichia coli and Klebsiella pneumoniae / 中华检验医学杂志

Objective To investigate the prevalence,genotype and epidemiology of plasmid- mediated AmpC enzyme of Escherichia coli and Klebsiella pneumoniae.Methods A total of 67 clinical isolates of nonrepetitive cefoxitin-resistant Escherichia coli and Klebsiella pneumoniae collected by Fuzhou General Hospital and Fujian Provincial Hospital during a period of Sept.2004 to Mar.2005 were detected by three-dimensional extract test for AmpC enzyme,and PCR for AmpC enzyme and other ?-lactamase gene amplification and DNA sequencing were carried out for genotype of ?-lactamase.Plasmid transformation experiment was used to study the transfer of cefoxitin resistance.The homology of the isolates was determined by ERIC-PCR fingerprinting.Results At two hospitals in Fuzhou,the prevalence of plasmid-mediated AmpC enzyme among cefoxitin-resistant Escherichia coli and Klebsiella pneumoniae were 16.7% and 10.5%, 8.0% and 0,respectively.Two isolates of Klebsiella pneumoniae produced DHA-1 plasmid-mediated AmpC enzyme,and 4 isolates of Escherichia cob and one strain of Escherichia coli produced CMY-2 and CMY-22 plasmid-mediated AmpC enzyme respectively.Furthermore,5 strains of Escherichia coli with CMY AmpC enzyme were also found simuhaneously to produce TEM-144,CTX-M-27,CTX-M-14 and TEM-1 ?-lactamase respectively.Three strains of Escherichia coli and one isolate of Klebsiella pneumoniae could transfer cefoxitin resistance to acceptant bacillus.ERIC-PCR fingerprinting reveals 2 strains of Klebsiella pneumoniae came from same clone,but 5 strains of Escherichia coli came from different clones.Conclusions The clinical isolates of Klebsiella pneumoniae producing DHA-1 plasmid-mediated AmpC enzyme and Escherichia coli producing CMY-2,CMY-22 plasmid-mediated AmpC enzyme are found in Fuzhou.CMY-22 AmpC enzyme and TEM-144 ?-lactamase are the first reported in the world,GenBank accession number: DO256079,DO256080

Prokaryotic expression and purification of human Smith D1 antigen / 中华检验医学杂志

Objective To obtain recombinant human Smith D1 (Sm D1) antigen and establish detecting assay.Methods Human Smith D1 antigen was synthesized by PCR using human Leukemic cDNA. The prokaryotic expression vector pGEX-ST-Sm D1 was constructed and transformed into E.coli.BL21 cell.Protein expressed under the induction of IPTG.We established DIGFA for detecting anti-Sm D1 antibodies with purified Sm D1 antigens.Results Sequence and restriction analysis revealed Sm D1 gene was cloned in frame into pGEX-5T,SDS-PAGE profile showed a clear protein band with a relative molecular weight of 39 000 and western blotting indicated that the expressed product specifically reacted to polyclonal anti-human Sm D1 genes.There was no significant difference between DIGFA and IB.The agreement between DIGFA and IB was 91.7% as calculated by Kappa statistical method.The sensitivity and specificity of DIGFA were 100% and 83.3% repectively.Conclusions Human Sm D1 gene is successfully cloned、 expressed and purification.The DIGFA,using purified Sm D1 antigens,is as good as IB,rather simpler, more rapid and reliable assay.

Eukaryotic Expression and Primarily Application of Human Smith D1 Antigen in Methylotrophic Yeast Pichia pastoris / 微生物学通报

To clone, express and primarily use human autoantigen Sm D1 in methylotrophic yeast Pichia Pastoris. The gene Sm D1 was cloned by PCR.The PCR product was inserted into the vector pPIC9k. The recombinant plasmid pPIC9k- Sm D1 was transformed into yeast SMD1168 by electroporation. The positive clones were screened in MD plates. The high copy number transformants were rapidly selected by using G418 and were induced by methanol. Supernatants after induction were analyzed by SDS-PAGE and im-munodot. The PCR product was showed about 360 bp in size which was in accordance with predicted. The pPIC9k-Sm D1 showed the same seqencing result with GenBank’s report and restriction enzyme analysis confirmed our prediction. The pPIC9k-Sm D1 positive clone produced an about 16 kD protein which had natural immunogenicity of human autoantigen Sm D1 by SDS-PAGE and immunodot. The sensitivity and specificity of immunodot were 96% and 100%, respectively. The agreement between immunodot and im-munoblot was 98%. Successfully cloning and high-level expression of human autoantigen Sm D1 in methy-lotrophic yeast Pichia pastoris laid a foundation for further research work.