[Effects of non-surgical periodontal therapy on serum inflammatory markers and metabolic level in obese rats].

OBJECTIVE: To investigate the effects of non-surgical periodontal therapy on serum inflammatory factors and metabolism levels in obese rats with experimental periodontitis. METHODS: Sixteen obese rats with experimental periodontitis were randomly divided into treatment group and control group with non-surgical periodontal therapy and no treatment, respectively. Oral glucose tolerance test was performed before treatment and 2 weeks after the treatment. All the rats were sacrificed 2 weeks after treatment and the orbital vein blood was taken to detect fasting blood glucose, fasting insulin, and serum level of C-reactive protein (CRP). Results Two weeks after periodontal treatment, fasting blood glucose (t=2.445, P=0.034) and beta cell function index (t=-2.543, P=0.027) were significantly lower in the treatment group than in the control group. Compared with those in the control group, CRP level (t=2.388, P=0.028) and the area under the curve in the oral glucose tolerance test (t=12.053, P=0.000) decreased significantly in the treatment group. CONCLUSION: Non-surgical periodontal treatment can reduce serum CRP level and improve glucose metabolism in obese rats.

[Beneficial effect of periodontal therapy on insulin resistance and lipid metabolism in obese rats with periodontitis].

OBJECTIVE: To investigate the effect of periodontal therapy in controlling periodontitis and on insulin resistance and lipid metabolism in obese rats with periodontitis. METHODS: Sprague-Dawley rats were randomized into normal group (group C), obese group (group O), periodontitis combined with obesity group (group P) and periodontal treatment group (group T). The obese rats in groups P and T were subjected to ligation of the maxillary second molar with silk thread to induce experimental periodontitis, and the rats in group T received periodontal therapy after the ligation. All the rats were sacrificed at the age of 24 weeks for measurement of blood lipids, insulin and blood glucose levels, and insulin resistance index (HOMA-IR) was calculated. The expressions of insulin receptor substrate-1 (IRS-1) and IRS-2 in the liver tissues were detected using real-time quantitative polymerase chain reaction (RT-PCR). RESULTS: Compared with the obese rats in group O, the rats in group P showed significantly higher HOMA-IR and LDL-C and lower expressions of IRS-1 and IRS-2 mRNA expression and HDL-C level (P<0.05). Compared with those in group P, the mRNA expressions of IRS-1 and IRS-2 and HDL-C level were significantly increased and LDL-C level, TC level and HOMA-IR were all decreased in group T (P<0.05), but the level of TG was comparable between the two groups. Pathological examination revealed lessened inflammatory cell infiltration and tissue destruction in the upper jaw of the rats in group T; the rats in group P presented with the most obvious upper jaw destruction and steatosis and inflammatory cell infiltration in the liver. CONCLUSION: Periodontal inflammation can downregulate the expression of IRS-1 and IRS-2 and increase insulin resistance and dyslipidemia in obese rats. Periodontal therapy produces a beneficial effect in improving insulin resistance and reducing dyslipidemia in obese rats.

[Construction of gtfB/CAT eukaryotic expression plasmid of Streptococcus mutans in mammalian cells].

PURPOSE: The study aimed to evaluate the expression of recombinant plasmid pVAX1- gtfB/CAT in mammalian COS-7 cells. METHODS: The eukaryotic plasmid carrying encoding gene of gtfB/CAT of Streptococcus mutans was constructed and introduced into COS-7 cells by lipofectamine reagent. The transient protein expression was detected by immunochemistry technique in COS-7 cells. RESULTS: The positive expression of gefB/CAT was detected in plasma of the cells which were transfected with recombinant plasmid pVAX1- gtfB/CAT. The cells which were transfected with pVAX1 were negative for gtfB/CAT expression. CONCLUSIONS: GtfB/CAT can be translated and expressed in COS-7 cells after transfected with recombinant plasmid pVAX1- gtfB/CAT. The expressed protein is located in the plasma and the protein is able to combine with anti- gtfB/CAT antibody. The expressed protein has the antigenicity and recombinant plasmid pVAX1- gtfB/CAT is a candidate vaccine.Supported by Key Research Project of Bureau of Education of Guizhou Province (Grant No.2004119).