Yan Jiang

Guiyang Medical University, Kuei-yang, Guizhou Sheng, China

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Publications (13)16.97 Total impact

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    ABSTRACT: Mammalian β-defensins are small cationic peptides of approximately 2-6 kDa that have been implicated in mediating innate immune defenses against microbial infection. This present study investigated the activity of mouse β-defensin 3 (MBD3) against bacterial and yeast drug-resistant strains in vitro, and whether this molecule acts in synergy with antibiotics. Minimum inhibitory concentrations (MICs) and minimum bactericidal/fungicidal concentrations (MBC/MFC) of recombinant MBD3 (rMBD3) were determined by microdilution assays against different strains of Staphylococcus aureus and Candida albicans. rMBD3 inhibited the growth of S. aureus (MIC, 25 μg/ml) and C. albicans (MIC, 25 μg/ml), and showed fungicidal activity against this yeast (MFC, 100 μg/ml). The influences of rMBD3 on S. aureus and C. albicans cells were examined using electron microscopy. Cells treated with rMBD3 showed morphological and structural changes, including delamination and perforation of the peripheral cell walls, porosity, and inanition of the cytoplasmic contents. Synergistic activities of rMBD3 with different antibiotics were assessed using checkerboard tests. Interestingly, the anti-methicillin-resistant S. aureus activity of rMBD3 in combination with ampicillin was synergistic; however, this was not the case against S. aureus (ATCC 25923). Combinations of rMBD3 with itraconazole, amphotericin or 5-fluorocytosine were synergistic against the two tested C. albicans strains. These results support the interest devoted to defensins as a novel class of antimicrobial agents, and highlight their abilities to potentiate the activities of conventional antibiotics.
    Journal of Materials Science Materials in Medicine 04/2012; 23(7):1723-8. · 2.14 Impact Factor
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    ABSTRACT: The effect of serum from rats supplemented with selenium and zinc on the proliferation of human esophageal cancer cell line Eca109 was observed by serophysiology. Rats were randomly divided into seven groups. Eight rats in each group were fed with basic feeds (deprived of both selenium and zinc). The experimental rat groups were supplemented with selenium or zinc at low or high dosage intragastrically for 30 days Serum selenium and zinc content of rats was measured by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Flame Atomic Absorption Spectrophotometry (FAAS). MTT assay,3H-TDR incorporation and flow cytometry were used to explore the effect of serum from different rat groups on the growth and proliferation of cancer cell line Ecal09 cells. (1) The content of serum zinc in the high zinc group was the highest and the content of serum zinc was the lowest in basic diet group. The content of serum selenium in high selenium and high zinc group was the highest and the content of serum selenium was the lowest in the basic diet group. (2) In comparing the growth of control cancer cell group cultured with calf serum, the growth of cancer cells cultured with the serum from high selenium and high zinc rats was inhibited in culturing for 72 h, but the growth of normal liver cells were also inhibited. The growth of cancer cells were promoted by serum from other groups. (3) Both MTT assay and 3H-TDR incorporation test showed that the DNA synthesis in cancer cells was inhibited by the serum from high selenium and high zinc group, but the DNA synthesis of normal liver cells was also inhibited by this type of serum. The result of DNA synthesis in other cell groups was closed to the control group. Low serum selenium and zinc might promote the growth of EC cell. Elevating the content of serum selenium and zinc by increasing selenium and zinc intake might inhibit EC cell proliferation.
    Wei sheng yan jiu = Journal of hygiene research 03/2012; 41(2):185-90.
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    ABSTRACT: Influenza causes significant morbidity and mortality. Mammalian β-defensins are small peptides of about 4.5-6 kDa in mass and are effectors of the innate immune response with potent antimicrobial activity. In this paper, we focused on the anti-influenza A activity of the recombinant mouse β-defensin 3 (rMBD-3) in vivo and in vitro. The rMBD-3 peptide was added to Madin-Darby canine kidney (MDCK) cells at different stages of influenza A virus (IAV) A/PR/8/34 (H1N1) infection and its virus inhibitory properties were determined. Mice were infected with IAV and treated with rMBD-3 peptide from 12 h post-infection. The effect of rMBD-3 peptide was determined by pulmonary viral load, pathology and mortality. In addition, the expression of interleukin (IL)-12, interferon (IFN)-γ and tumour necrosis factor (TNF)-α genes in mice with or without rMBD-3 treatment was determined by semi-quantitative reverse transcriptase PCR. rMBD-3 was shown to protect MDCK cells against IAV infection and had a major role in inhibition of adsorption and uptake by cells infected with IAV. Following the addition of 100 μg/ml rMBD-3 to MDCK cells medium, approximately 80% of cells were protected from infection in vitro. rMBD-3 given by tail vein injection (10 mg/kg/day) was the most effective method to improve the survival rate of the mice. Treatment with rMBD-3 was found to up-regulate IFN-γ and IL-12 gene expression, but reduced expression of the TNF-α gene. These results demonstrate that rMBD-3 possesses anti-influenza virus activity both in vivo and in vitro that might be of therapeutic use.
    Antiviral chemistry & chemotherapy 02/2012; 22(6):255-62.
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    ABSTRACT: The objective of this study was to develop a new Tween-80 microbiological assay (Tween-80 MBA) to determine human or animal serum folate levels and to verify its reliability. The effects of the Lactobacillius casei subspecies rhamnosus (L. casei, ATCC No. 7469) inoculum concentration, incubation time, and Tween-80 on L. casei growth were studied, and the serum folate levels were investigated. Serum samples were collected from patients with esophageal cancer (EC) and healthy control subjects in Yanting, healthy adult subjects in Chengdu, Sichuan, and in male Sprague-Dawley rats. Optimal conditions for the new MBA were as follows: 1.28 x 10(7) CFU/mL working inoculum, vitamin folic acid assay broth with 0.24% (w/w) Tween-80, and anaerobic incubation with L. casei at 37 degrees C for 22 h. Under the optimal conditions, the working curve was in simple linear rather than logarithmic equation; the linear working curve of the folic acid standard working solution concentration versus the turbidity (adsorption value) of medium with L. casei ranged from 0.05 to 1.00 microg/L; the linear correlation coefficient was 0.9989 (SD 0.0007); the recovery rate of folate was 105.4-112.7%; and the minimum concentration for detecting folate was 0.03 microg/L. The RSD within-day and between-day precisions were 5.6 and 3.3%, respectively. The serum folate level of 100 EC patients was 6.4 (SEM 0.4) microg/L which was significantly lower than that of healthy control subjects [8.0 (SEM 0.6) microg/L, n = 100, P=0.020]. The new Tween-80 MBA is considered to be a reliable method for measuring serum folate level.
    Journal of AOAC International 01/2012; 95(5):1505-10. · 1.23 Impact Factor
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    ABSTRACT: Influenza (flu) pandemics have posed a great threat to human health in the last century. However, current vaccination strategies and antiviral drugs provide limited protection. RNA interference (RNAi) is an effective means of suppressing influenza virus replication. PB1 is the critical protein subunit of the influenza virus RNA polymerase. The gene encoding this protein, PB1, is highly conserved among different subtypes of IAV and was therefore chosen as the target in this study. The oligonucleotide, PB1-shRNA, contains a 21-bp siRNA corresponding to nucleotides 1,632 to 1,652 of PB1 linear vRNA with BamHI or EcoRI restriction enzyme sites incorporated at the ends. The PB1-shRNA oligonucleotide was directionally cloned into the RNAi-ready pSIREN-shuttle vector. The correct structure of the resulting pSIREN/PB1 plasmid was confirmed by restriction endonuclease digestion. Madin-Darby canine kidney (MDCK) cells were transfected with pSIREN/PB1 and subsequently infected with IAV at an MOI of 0.1 (A/PR/8/34, H1N1). The virus titer in cell culture supernatants was determined 48 hours later, and it was found that virus growth was inhibited by more than 50-fold relative to controls. Furthermore, embryonated eggs and mice were inoculated with liposome-encapsulated pSIREN/PB1 and then challenged with the A/PR/8/34 virus. The results showed at least a 100-fold inhibition in virus replication in egg allantoic fluid and a survival rate of between 50% and 100% in experimental mice. This study demonstrates that PB1-shRNA expressed by the recombinant plasmid pSIREN/PB1 inhibits influenza A virus replication both in vitro and in vivo. These observations provide a foundation for the development of a new and efficient treatment of influenza infections.
    Archives of Virology 08/2011; 156(11):1979-87. · 2.28 Impact Factor
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    ABSTRACT: Mature mouse beta defensin 2 (mBD2) is a small cationic peptide with antimicrobial activity. Here we established a prokaryotic expression vector containing the cDNA of mature mBD2 fused with thioredoxin (TrxA), pET32a-mBD2. The vector was transformed into Escherichia Coli (E. coli) Rosseta-gami (2) for expression fusion protein. Under the optimization of fermentation parameters: induce with 0.6 mM isopropylthiogalactoside (IPTG) at 34°C in 2×YT medium and harvest at 6 h postinduction, fusion protein TrxA-mBD2 was high expressed in the soluble fraction (>95%). After cleaved fusion protein by enterokinase, soluble mature mBD2 was achieved 6 mg/L with a volumetric productivity. Purified recombinant mBD2 demonstrated clear broad-spectrum antimicrobial activity for fungi, bacteria and virus. The MIC of antibacterial activity of against Staphylococcus aureus was 50 μg/ml. The MIC of against Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans) was 12.5μg/ml and 25μg/ml, respectively. Also, the antimicrobial activity of mBD2 was effected by NaCl concentration. Additionally, mBD2 showed antiviral activity against influenza A virus (IAV), the protective rate for Madin-Darby canine kidney cells (MDCK) was 93.86% at the mBD2 concentration of 100 μg/ml. These works might provide a foundation for the following research on the mBD2 as therapeutic agent for medical microbes.
    Brazilian Journal of Microbiology 07/2011; 42(3):1180-7. · 0.76 Impact Factor
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    ABSTRACT: Human influenza A virus (IAV) is a major cause of life-threatening respiratory tract disease worldwide. Defensins are small cationic peptides of about 2-6 kDa that are known for their broad-spectrum antimicrobial activity. Here, we focused on the anti-influenza A activity of mouse beta-defensin 2 (mBD2). The prokaryotic expression plasmid pET32a-mBD2 was constructed and introduced into Escherichia coli Rosseta gami (2) to produce recombinant mBD2 (rmBD2). Purified rmBD2 showed strong antiviral activity against IAV in vitro. The protective rate for Madin-Darby canine kidney cells was 93.86% at an rmBD2 concentration of 100 microg/ml. Further studies demonstrated that rmBD2 prevents IAV infection by inhibiting viral entry. In addition, both pretreatment and postinfection treatment with rmBD2 provided protection against lethal virus challenge with IAV in experimental mice, with protection rates of 70 and 30%, respectively. These results suggest that the mBD2 might have important effects on influenza A virus invasion.
    Archives of Virology 03/2010; 155(4):491-8. · 2.28 Impact Factor
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    ABSTRACT: Esophageal squamous cell carcinoma (ESCC) is prevalent in Yanting (YT) country located in southwestern China. Residents in the YT region have an unusual diet pattern and the role of the YT diet on the risk of ESCC is still uncertain. The present study was to examine the possible effects of sera from rats fed with the YT diet on proliferation of human esophageal cancer cell line Eca-109 by means of a sero-physiology approach. Firstly, two feasibilities were assessed to set up the sero-physiology method. We found that rats fed with a human adult diet in Chengdu region (ESCC-low-risk-area) for 30d had very close body weight gains in comparison with the control rats fed with the conventional diet, confirming the feasibility of feeding rats with a human diet without affecting their normal growth. Cell growth results showed that 5% non-deactivated rat serum had exactly the same effect on the proliferation of Eca-109 cells compared with the fetal bovine sera (FBS) control, confirming the feasibility of cultivating Eca-109 cells with the rat serum instead of FBS. Subsequently, cell proliferation results indicated that rats' sera fed with the YT diet significantly promoted Eca-109 cells proliferation but inhibited human normal liver epithelial cell line control HL7702 proliferation, whereas rats' sera fed with the Chengdu diet didn't have these effects on the two cell lines. The different effects of the two human diets on proliferation of Eca-109 cells demonstrated that the sero-physiology method is effective in studying the relationship between diet and cancer, and there maybe exist cancer-promoting factors in the YT diet.
    Nutrition and Cancer 01/2010; 62(4):543-53. · 2.70 Impact Factor
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    ABSTRACT: Mouse beta defensin-1 (mBD-1) is a cationic 37-amino acid antimicrobial peptide with three conserved cysterine disulfied bonds. It exhibits a broad antimicrobial spectrum, but mBD-1 against Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans) is poorly understood. This study describes the mBD-1 gene, the heterologous fusion expression of the peptide in Escherichia coli, and the bioactive assay of released mature mBD-1. By constructing the expression plasmid (pET32a-mBD1), high yields of soluble mBD-1 fusion protein (0.67 g/L) could be obtained in E. coli and cleaved by enterokinase. The digested product was further purified and desalted with the final amount of pure mature mBD-1 being 0.14 g/L. Classical fungi growth inhibition assay showed clear antifungal activity against C. albicans and C. neoformans with IC(50) of 5 and 2 microM, respectively. The results show that the mBD-1 control fungal colonization through hyphal induction, direct fungicidal activity, and the activity is suppressed by increasing NaCl concentration. Successful expression of the mBD-1 peptide in E. coli offers a basis for further studying its antifungal mechanisms and may provide significance in developing this peptide to an antifungal drug.
    Applied biochemistry and biotechnology 04/2009; 160(1):213-21. · 1.94 Impact Factor
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    ABSTRACT: Influenza (flu) pandemics have presented a threat to human health in the past century. Because of outbreaks of avian flu in humans in some developing countries in recent years, humans are more eager to find a way to control flu. Mammalian beta-defensins (beta-defensins) are associated primarily with mucosal and skin innate immunity. Previous studies have demonstrated antimicrobial properties of a variety of defensin peptides. We have identified the presence of mouse beta-defensin 1, 2, and 3 genes (Mbd-1, 2, and 3) in trachea and lung tissues by RT-PCR before and after infection with influenza virus. We constructed a eukaryotic expression plasmid containing Mbd-3, pcDNA 3.1(+)/MBD-3, and the plasmid was introduced into Madin-Darby canine kidney (MDCK) cells by transfection. The expression of Mbd-3 in MDCK cells was verified by immunofluorescence test, RT-PCR, and Western blot. The pcDNA 3.1(+)/MBD-3 plasmid was injected into mice to observe its effect against influenza A virus (IAV) in vivo. Mouse beta-defensin genes could be expressed in trachea and lung tissues before IAV infection, but expression of Mbd-2 and Mbd-3 was increased significantly after IAV infection. The survival rate of mice with MBD-3 against IAV challenge was 71.43%, and MDCK cells with MBD-3 could clearly inhibit IAV replication. The results demonstrated that mouse beta-defensins possess anti-influenza virus activity, suggesting that mouse beta-defensins might be used as agents to prevent and treat influenza.
    Archives of Virology 02/2009; 154(4):639-47. · 2.28 Impact Factor
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    ABSTRACT: Mouse beta defensin-1 (mBD-1) is a cationic peptide with broad antimicrobial activity. The mBD-1 gene was cloned and fused with TrxA to construct pET32-mBD1, which was transformed into E. coli BL21 (DE3). The optimal expression conditions of fusion protein TrxA–mBD1 were: cultivation at 32°C in 2×YT medium, induction with 0.2mM isopropylthio-d-galactoside (IPTG), and post-induction expression for 8h. The fusion protein was highly soluble (90.0%) and accounted for 65% of the total soluble protein; and its volumetric productivity reached 0.67g/l, i.e., 0.14g/l of recombinant mBD-1. At 5μM, purified recombinant mBD-1 killed 50% of Candida albicans.
    World Journal of Microbiology and Biotechnology 01/2009; 25(5):917-920. · 1.35 Impact Factor
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    ABSTRACT: To construct the eukaryotic recombinant plasmid pcDNA3.1a(+)-M2e/CtB which contains H1N1 M2e gene and cholera toxin B subunit gene (CtB) and to study the expression and immunity of recombinant protein M2e/CTB in NIH3T3 cells. M2e/CtB gene was cloned by PCR and digested with Hind III and Xho I. M2e/CtB was linked into pcDNA3.1a(+) to build eukaryotic expression plasmid pcDNA3.1a(+)-M2e/CtB. The pcDNA3.1a(+)-M2e/CtB was transfered into competent E.coli JM109. The transformed colonies were verified by Hind III and Xho I, PCR, and sequencing. The NIH3T3 cells were transfected with pcDNA3.1a(+)-M2e/CtB by positive ion polymer. The product of M2e/CtB gene with stable expression was analysed by immunofluorescence, RT-PCR sequencing, and Western blot. The digested pcDNA3.1a (+)-M2e/CtB contains correct M2e and CtB gene. Blastn results showed the genetic homongenicity of M2e and CtB were 100%, respectively. The pcDNA3.1a(+)-M2e/CtB efficiently expressed M2e/CTB protein in the eukaryotic NIH3T3 cells. The cell lysis and supernant both contained the M2e/CTB protein, which had the immunity and reactivity to both anti-M2e and anti-CTB. The relative molecular mass of M2e/CTB protein was about 18 000 analysed by Western blot. A new recombinant eukaryotic plasmid pcDNA3.1a(+)- M2e/CtB has been successfully constructed. The plasmid can express the fused protein of M2e with CTB. Our study will help further research into new and effective DNA vaccines against influenza virus A.
    Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology 04/2008; 24(3):263-6.
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    ABSTRACT: Sero-physiology method was used to observe the effects of sera from rats fed the diet of Yanting (high prevalence region of esophageal cancer) on proliferation of human esophageal cancer cell Eca-109. Male SD rats was submitted to three experimental diets. A standard diet, the healthy adults' diet and the Yanting's diet were fed for seven days. Body weights and diet intakes were measured every day. Methyl thiazolyl tetrazolium (MTT) assay were used to explore the optimal conditions of rats'sera culturing the cell Eca-109. Human normal liver epithelial cell (HL7702) and 10% deactivated bovine serum were respectively set as normal cell control and serum control. The effects of sera from rats fed the Yanting's diet on Eca-109 were observed by means of cell growth curve, cell doubling time analysis and 3H-thymidine incorporation. No significant differences of diet intakes and body weights between the rats fed the standard diet and the healthy adult diet were found. It was demonstrated that 5% non-deactivated rats' sera could replace 10% deactivated bovine serum in medium for culturing human esophageal cancer cell Eca-109. Contrast to the other three controls, sera from rats fed the Yanting's diet significantly promoted Eca-109 cells proliferation, while showed inhibitory effect on human normal liver epithelial cell (HL7702). The results showed that the diet of high prevalence region of Janting esophageal cancer could significantly promote the proliferation of human esophageal cancer cell Eca-109.
    Wei sheng yan jiu = Journal of hygiene research 04/2007; 36(2):226-30.