Mingxun Xing

Jilin University, Jilin, Jilin Sheng, China

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Publications (7)13.17 Total impact

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    ABSTRACT: Aims:  To investigate the antimicrobial efficacy of an alkaloid, harmaline alone and in combination with chlorhexidine digluconate (CHG) against clinical isolates of Staphylococcus aureus (S. aureus) grown in planktonic and biofilm cultures. Methods:  Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined for each micro-organism grown in suspension and in biofilm using microbroth dilution method. Chequerboard assays were used to determine synergistic, indifferent or antagonistic interactions between harmaline and CHG, and the some of results were verified by confocal laser scanning microscopy. Results:  Harmaline and CHG showed effective antimicrobial activity against suspensions and biofilm cultures of S. aureus, respectively. As determined by fractional inhibitory concentration index (FICI), synergistic antimicrobial effects between harmaline and CHG were observed in nine and 11 of the 13 S. aureus strains when in suspension and in biofilm, respectively. FICI values were from 0·375 to 1·25 when in suspension and from 0·25 to 1·25 when in biofilm. Conclusions:  Synergistic activity of harmaline and CHG against clinical isolates of S. aureus (in suspension and in biofilm) was observed in vitro. Significance and Impact of the Study:  This study might provide alternative methods to overcome the problem of drug-resistance of S. aureus both in suspension and in biofilm.
    Letters in Applied Microbiology 03/2012; 54(5):475-82. · 1.63 Impact Factor
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    ABSTRACT: Tuberculosis (TB) is still one of the most common causes of death in the world. The emergence of multidrug-resistant and extensively drug-resistant (XDR-TB) Mycobacterium tuberculosis (M. tuberculosis) strains has increased the importance of searching for alternative targets to develop new antimycobacterial drugs. Linezolid, the first of oxazolidinones, is active in vitro against M. tuberculosis, but the response mechanisms of M. tuberculosis to linezolid are still poorly understood. To reveal the possible mechanism of action of linezolid against M. tuberculosis, commercial oligonucleotide microarrays were used to analyze the genome-wide transcriptional changes triggered by treatment with subinhibitory concentrations of linezolid. Quantitative real-time RT-PCR was performed for selected genes to verify the microarray results. A total of 729 genes were found to be differentially regulated by linezolid. Among these, 318 genes were upregulated, and 411 genes were downregulated. A number of important genes were significantly regulated that are involved in various pathways, such as protein synthesis, sulfite metabolism, and genes involved in the cell envelope and virulence. This genome-wide transcriptomics approach produced the first insights into the response of M. tuberculosis to a linezolid challenge.
    Current Microbiology 03/2012; 64(6):530-8. · 1.52 Impact Factor
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    ABSTRACT: The acaricidal activity of trans-cinnamaldehyde was evaluated in vitro on Psoroptes cuniculi. In this study, different concentrations of trans-cinnamaldehyde were tested, and the observed mites mortality was compared with that observed in untreated and treated (Acacerulen R®) controls. The morphological changes in P. cuniculi treated with trans-cinnamaldehyde were examined with light microscopy. By the analysis of variance one-way test, up to 8 μg/ml of trans-cinnamaldehyde gave highly significant (P < 0.01) percentages of mite mortality compared with the untreated controls, but only up to 256 μg/ml, it showed the same efficacy of Acacerulen R®. At the same time, a bioassay was conducted by exposing mites to varying doses of trans-cinnamaldehyde in vitro cultures. The resulting data were analyzed by using a time-dose-mortality modeling technique, yielding the parameters for time and dose effects of P. cuniculi. The β value was 2.01, indicating that trans-cinnamaldehyde had a good activity to kill P. cuniculi adults. Based on the time-dose-mortality relationships fitted and the virulence indices estimated, trans-cinnamaldehyde is a promising microbial agent for mites control.
    Parasitology Research 02/2012; 110(4):1321-6. · 2.85 Impact Factor
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    ABSTRACT: Mycoplasmosis caused by mycoplasma has immensely reduced the performance of commercial animal husbandry, along with prevalence and increase of drug resistance in mycoplasma, thus new agents and therapies are urgently needed. Triclosan is a broad spectrum antimicrobial agent with a favorable safety profile. In the present study, we tested the antimycoplasmal activity of triclosan alone, as well as the in-vitro interaction of triclosan and the fluoroquinolones, gatifloxacin (GAT), moxifloxacin (MXF), levofloxacin (LVX), sparfloxacin (SPX), ciprofloxacin (CIP), enrofloxacin (EFX), and norfloxacin (NOR), against five mycoplasma species. This study demonstrated that triclosan had antimycoplasmal activity against both fluoroquinolones-sensitive species and a fluoroquinolones-resistant species isolated from clinic, with minimum inhibitory concentrations (MICs) of 16.0-64.0 μg/mL and 64.0 μg/ mL, respectively. A synergistic antimycoplasmal effect between triclosan and GAT, MFX or EFX against the five mycoplasma species was observed, with modulation factors (MFs) of 4-8, 4-16, 8-32, respectively, and fractional inhibitory concentration indexes (FICIs) of 0.375- 0.500, 0.350-0.500, 0.281-0.375, respectively. The combination of triclosan with LVX, SPX, CIP or NOR displayed either synergistic activity or indifference against the same mycoplasma species with MFs of 2-64, 4-16, 2-16, 2-64, respectively, while FICI values range from 0.516- 0.750, 0.500-0.625, 0.306-0.750, and 0.615-0.750, respectively. No antagonism was observed for any drug combination against any of the species tested. To the best of our knowledge, this is the first report that triclosan has synergistic activity with fluoroquinolones against mycoplasma species.
    Iranian journal of pharmaceutical research (IJPR) 01/2012; 11(4):1111-9. · 0.54 Impact Factor
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    ABSTRACT: The targeting of Staphylococcus aureus biofilm structures are now gaining interest as an alternative strategy for developing new types of antimicrobial agents. Magnolol (MOL) shows inhibitory activity against S. aureus biofilms and Triton X-100-induced autolysis in vitro, although there are no data regarding the molecular mechanisms of MOL action in bacteria. The molecular basis of the markedly reduced autolytic phenotype and biofilm inhibition triggered by MOL were explored using transcriptomic analysis, and the transcription of important genes were verified by real-time RT-PCR. The inhibition of autolysis by MOL was evaluated using quantitative bacteriolytic assays and zymographic analysis, and antibiofilm activity assays and confocal laser scanning microscopy were used to elucidate the inhibition of biofilm formation caused by MOL in 20 clinical isolates or standard strains. The reduction in cidA, atl, sle1, and lytN transcript levels following MOL treatment was consistent with the induced expression of their autolytic repressors lrgA, lrgB, arlR, and sarA. MOL generally inhibited or reversed the expression of most of the genes involved in biofilm production. The growth of S. aureus strain ATCC 25923 in the presence of MOL dose-dependently led to decreases in Triton X-100-induced autolysis, extracellular murein hydrolase activity, and the amount of extracellular DNA (eDNA). MOL may impede biofilm formation by reducing the expression of cidA, a murein hydrolase regulator, to inhibit autolysis and eDNA release, or MOL may directly repress biofilm formation. MOL shows in vitro antimicrobial activity against clinical and standard S. aureus strains grown in planktonic and biofilm cultures, suggesting that the structure of MOL may potentially be used as a basis for the development of drugs targeting biofilms.
    PLoS ONE 01/2011; 6(10):e26833. · 3.53 Impact Factor
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    ABSTRACT: Sodium houttuyfonate (SH), an addition compound of sodium bisulfite and houttuynin, showed in vitro antibacterial activity against 21 Staphylococcus aureus (S. aureus) strains grown in planktonic cultures. Microarray results showed decreased levels of autolysin atl, sle1, cidA and lytN transcripts in the SH-treated strain as compared to the control strain, consistent with the induction of the autolytic repressors lrgAB and sarA and with the downregulation of the positive regulators agrA and RNAIII. Triton X-100-induced autolysis was significantly decreased by SH in S. aureus ATCC 25923, and quantitative bacteriolytic assays and zymographic analysis demonstrated SH-mediated reduction of extracellular murein hydrolase activity in these cells. Anti-biofilm assay showed that SH is poorly active against S. aureus grown in biofilm cultures, whereas SH diminished the amounts of extracellular DNA (eDNA) of S. aureus in a dose-dependent manner, which suggested that SH may impede biofilm formation by reducing the expression of cidA to inhibit autolysis and eDNA release in the early phase. Some of the microarray results were confirmed by real-time RT-PCR.
    Molecules 01/2011; 16(10):8848-65. · 2.43 Impact Factor
  • M Xing, Y Du, X Wang, L Niu, X Chen
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    ABSTRACT: We present a simplified paraffin embedding method suitable for unsuberized or unlignified small botanical samples (diameter < 0.3 cm). Only 2 h are required to yield plant tissues embedded in paraffin for anatomical observation and molecular analysis. Our method achieved morphological preservation of cell structures and conservation of nucleic acids that were equivalent to the traditional protocol. Fourier transform infrared spectrometry showed that the degree of degradation of the cytoplasmic components (e.g., protein) resulting from our simplified protocol was similar to that of the traditional protocol. The DNA samples embedded using the simplified method was extractable and could be used for PCR analysis. The DNA quality was equivalent to that embedded using the traditional method.
    Biotechnic & Histochemistry 11/2009; 85(4):241-6. · 0.67 Impact Factor