OBJECTIVEThe purpose of this study is to construct a pyruvate oxidase gene deficiency variant strain of Streptococcus oralis (S. oralis).

METHODSThe sopox gene, which was got using polymerase chain reaction (PCR), and the 130-basepair segment of which was cut down with endonuclease BamHI, and transferred into S. oralis (ATCC10557) by using electrotransformation. The authors obtained a variant strain of S. oralis, and then the catalase activity of the first culture and 3-4 subcultures was examined.

RESULTSThe authors obtained a pyruvate oxidase gene deficiency variant strain of S. orlis. The catalase activity examination showed that the ability of producing H2 O2 of the variant strain of S. orlis declined, whose catalase activity was between those of the positive control (ATCC10557) and the negative control (Escherichia coli, JM109). But the produced H2 O2 quantity of their subcultures was less than that of the negative control.

CONCLUSIONThe construction of the pyruvate oxidase gene deficiency variant strain of Streptococcus oralis is successful.

Cloning, Molecular ; Genes, Bacterial ; Genetic Engineering ; Genetic Variation ; Polymerase Chain Reaction ; Pyruvate Oxidase ; genetics ; Streptococcus oralis ; enzymology ; genetics

OBJECTIVETo investigate the effect of metformin in protecting against advanced glycation end products (AGEs)-induced apoptosis in human primary dermal fibroblasts.

METHODSFibroblasts were exposed to 100, 200, or 300 µg/mL AGEs, 300 µg/mL bovine serum albumin (BSA), or 300 µg/mL AGEs and 1 mmol/L metformin for 24, 48, or 72 h. The exposed cells were examined for cell apoptosis using a cell counting kit. The expressions of caspase-3, Bax and Bcl-2 protein in the fibroblasts treated for 72 h were detected with Western blotting.

RESULTSAGEs exposures caused significant dose- and time-dependent apoptosis in the fibroblasts. A 72-h exposure to 300 µg/mL AGEs resulted in obviously increased apoptosis of the fibroblasts compared to the control group (0.72 ± 0.02 vs 1 ± 0.04, P<0.05), and metformin significantly decreased AGEs-induced apoptosis (0.98 ± 0.02 vs 0.72 ± 0.02, P<0.05). The expressions of caspase-3 and Bax protein were significantly increased (P<0.05) and Bcl-2 protein expression was decreased (P<0.05) with a lowered Bcl-2/Bax ratio in AGEs-treated fibroblasts (P<0.05), and such changes were significantly reversed by metformin treatment (P<0.05).

CONCLUSIONMetformin can antagonize AGEs-induced apoptosis in human dermal fibroblasts by regulating the expressions of caspase-3, Bax and Bcl-2.

Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cells, Cultured ; Dermis ; cytology ; Fibroblasts ; cytology ; drug effects ; Glycation End Products, Advanced ; adverse effects ; Humans ; Metformin ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; bcl-2-Associated X Protein ; metabolism