ABSTRACT
ObjectiveTo study the virulence and biofilm inhibition effect of Fufang Huangbai Fluid Paint （FFHBFP） on methicillin-resistant Staphylococcus aureus （MRSA）， and to explore the antibacterial effect of FFHBFP on MRSA， which provides a theoretical basis and reference for clinical medication. MethodFirstly， the microdilution method and time–growth curve were used to determine the minimum inhibitory concentration （MIC） of FFHBFP and vancomycin （VAN） against MRSA and the effect on bacterial growth. The effects of FFHBFP and VAN on the inhibition of MRSA virulence factor lipase and restoration of hydrogen peroxide （H2O2） sensitivity were detected under sub-minimum inhibitory concentration （sub-MIC）. The inhibitory effect of FFHBFP and VAN on MRSA biofilm formation and maturation was detected by the microplate method. The morphological changes of mature biofilms before and after administration were observed under a scanning electron microscope （SEM）. Real-time polymerase chain reaction （Real-time PCR） was utilized to detect the effect of 50.600 g·L-1 concentration of FFHBFP on the expression of MRSA virulence gene crtM and biofilm-forming genes fnbA and icaA. Finally， molecular docking technology was used to predict the mechanism of potential antibacterial active ingredients of FFHBFP in inhibiting the virulence and biofilm of MRSA. ResultThe MIC of VAN was 2 mg·L-1， and VAN below 1 mg·L-1 exerted no effect on MRSA growth. The MIC of FFHBFP was not determined， while the 101.200-202.400 g·L-1 original solution inhibited MRSA growth. Compared with the blank group and the VAN group， sub-MIC （25.300-50.600 g·L-1 original solution） inhibited lipase and recovered MRSA sensitivity to H2O2 （P<0.01）. The results of the microplate method showed that FFHBFP （25.300-202.400 g·L-1 original solution） inhibited biofilm formation and maturation （P<0.05， P<0.01）. The SEM exhibited that FFHBFP made the structure of biofilm loose and the size of the bacteria varied. FFHBFP at 50.600 g·L-1 concentration can inhibit the expression of related virulence genes and biofilm-forming genes （P<0.05， P<0.01）， and molecular docking results also showed that the main antibacterial active ingredients in FFHBFP have good binding ability to the target. ConclusionFFHBFP that cannot directly kill MRSA exerts clinical efficacy by impairing virulence expression， biofilm formation， and other pathogenic properties.
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Objective:To observe the effect of combination of Tanreqing injection(Tanreqing) and imipenem-cilastatin on extensively-drug resistant Pseudomonas aeruginosa (XDPA), and study the mechanism of the combination. Method:The minimum inhibitory concentrations (MICs) of Tanreqing and imipenem-cilastatin against planktonic XDPA strain isolated in clinic were determined by the broth microdilution method. The checkerboard method was used to evaluate the combination effect. The bacterial metabolic activity in mature biofilm was studied by microtiter-plate test. The destructive effect of combination drugs on dynamic biofilm was observed by using BioFlux system, and viable cells were examined by confocal laser scanning microscope (CLSM) after treatment. The scanning electron microscopy (SEM) was used for observing Pseudomonas aeruginosa and length measurement. Result:The MIC values of imipenem-cilastatin and Tanreqing were 512 mg·L-1 and more than 16 500 mg·L-1. The checkerboard analysis showed that Tanreqing could enhance the sensitivity of imipenem-cilastatin, while the combination drugs synergistically inhibited the growth of bacteria. Compared with the control group or the imipenem-cilastatin individual group, the combined drugs significantly reduced the amount of living bacteria in the biofilm (PPPConclusion:Tanreqing and imipenem-cilastatin synergistically inhibit the bacterial growth in planktonic and biofilm states, and destruct biofilms.
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<p><b>OBJECTIVE</b>To study the effects of Ginkgo biloba extract 50 (GBE50) on inflammatory cytokines and glia cell injury in the prefrontal cortex and hippocampus of aging rats and its probable mechanism. Methods Totally 45 male SD rats were randomly divided into 4 groups, i.e., the normal control group (n=12), the model group (n=11), the low dose GBE50 group (n=10), and the high dose GBE50 group (n=12). The aging rat model was intraperitoneally injected with D-galactose to establish the aging model for 42 days. Starting from the 22nd day of modeling, rats in the low dose GBE50 group and the high dose GBE50 group were administered by gastrogavage with 75 mg/kg and 150 mg/kg respectively. The protein contents and mRNA expressions of IL-1beta, IL-6, and TNF-a in the prefrontal cortex and hippocampus of rats were detected by radioimmunoassay and Real-time fluorescence quantitative PCR assay respectively. The ultrastructural changes of glia cells in the hippocampal CA1 region were observed by transmission electron microscope. Results The protein contents and mRNA expressions of IL-1beta and TNF-alpha in the prefrontal cortex and the hippocampus of aging rats obviously increased when compared with the normal control group (P < 0.05, P < 0.01). The content of IL-6 in the hippocampus of aging rats obviously decreased (P < 0.01). Compared with the model group, the protein content and mRNA expression of IL-1beta in the prefrontal cortex and the hippocampus were obviously downregulated in the low and high dose GBE50 groups. The content of TNF-alpha in the prefrontal cortex was obviously downregulated in the low and high dose GBE50 groups, the content of TNF-alpha in the hippocampus was obviously downregulated in the low dose GBE50 group (P < 0.05, P < 0.01). The content of IL-6 in the prefrontal cortex of the low dose GBE50 group was up-regulated. The content of IL-6 in the hippocampus of the high dose GBE50 group was also upregulated. The mRNA expression of IL-6 in the prefrontal cortex of the low and high dose GBE50 groups obviously increased (P < 0.05, P < 0.01). Low and high dose GBE50 showed obvious recovery on the ultrastructural damage of glia cells in the hippocampal CA1 region.</p><p><b>CONCLUSIONS</b>GBE50 showed inhibitive effects on the inflammatory reaction of nerves of aging rats. Its mechanism might be possibly correlated with its regulatory effects on the cytokines in the prefrontal cortex and the hippocampus, as well as the ultrastructures of glia cells in the prefrontal cortex and hippocampus to some degree.</p>