The granular carbides formed from hot deformation in multiple alloying wear resistant cast iron were studied through the observation by means of optical microscope, SEM and TEM. The experimental results show that carb...The granular carbides formed from hot deformation in multiple alloying wear resistant cast iron were studied through the observation by means of optical microscope, SEM and TEM. The experimental results show that carbides with large size are formed from original short rhabdoid carbides existing in cast, those with small size directly nucleate in the matrix. Carbides with the size between the above are formed from precipitation induced by hot deformation. The bigger the deformation is, the larger the number of microsized granular carbides is. The mechanisms of nucleation and growth of granular carbides and the function of RE were discussed.展开更多
Summary: The expression and functional activity of multiple drug resistance (MDR1) gene in human normal bone marrow CD34+ cells was observed. Human normal bone marrow CD34+ cells were enriched with magnetic cell sorti...Summary: The expression and functional activity of multiple drug resistance (MDR1) gene in human normal bone marrow CD34+ cells was observed. Human normal bone marrow CD34+ cells were enriched with magnetic cell sorting (MACS) system, and then liposome-mediated MDR1 gene was transferred into bone marrow CD34+ cells. Fluorescence-activated cell sorter was used to evaluate the expression and functional activity of P-glycoprotein (P-gp) encoded by MDR1 gene. It was found that the purity of bone marrow CD34+ cells was approximately (91±4.56) % and recovery rate was (72.3±2.36) % by MACS. The expression of P-gp in the transfected CD34+cells was obviously higher than that in non-transfected CD34+ cells. The amount of P-gp in non-transfected CD34+ cells was (11.2±2.2) %, but increased to (23.6±2.34) % 48 h after gene transfection (P<0.0l). The amount of P-gp was gradually decreased to the basic level one week later. The accumulation and extrusion assays showed that the overexpression of P-gp could efflux Rh-123 out of cells and there was low fluorescence within the transfected cells. The functional activity of P-gp could be inhibited by 10 μg/ml verapamil. It was suggested that the transient and highly effective expression and functional activity of P-gp could be obtained by liposome-mediated MRD1 transferring into human normal bone marrow CD34+ cells.展开更多
BACKGROUND The upsurge of antibiotic resistance is a significant challenge to public health,and the dry pipeline of new antibiotics has prompted the discovery of alternative treatment approaches.Enterococcus faecalis(...BACKGROUND The upsurge of antibiotic resistance is a significant challenge to public health,and the dry pipeline of new antibiotics has prompted the discovery of alternative treatment approaches.Enterococcus faecalis(E.faecalis)isolates are often multidrugresistant,posing challenges to antibiotic therapy.Bacteriophage therapy is being explored as an alternative method to treat the growing population of antibioticresistant infections.Nevertheless,many inherent limitations of phages diminish their therapeutic utility,notably the restricted host range and quick development of mutants.The specific types and quantities of bacteriophages and antibiotics may be crucial in generating the optimal phage-antibiotic synergy.AIM To optimize the doses,order,and timing to optimize the synergy of phages and vancomycin on different bacteria states.METHODS A volume of 180μL of E.faecalis bacteria in the logarithmic growth phase,with a concentration of approximately 1×10^(8)colony forming units(CFUs)/mL,was introduced onto a microtitre plate.Subsequently,20μL of phage suspension(1×10^(6)PFUs/mL),vancomycin(16μg/mL),or a combination of both was introduced into the designated wells in the specified sequence and incubated at 37°C for 48 hours.The number of live bacteria was counted at different time points using standardized CFU counting protocols.RESULTS The biofilm model demonstrated that combining phages with vancomycin can eradicate the biofilm.Sequential therapy,involving phage application 8 hours before the antibiotic at a concentration of 108 PFUs/mL,proved the most efficient in eliminating the biofilms and killing the planktonic form of E.faecalis.CONCLUSION The combination of phageɸEFP01 at a higher concentration with a subinhibitory concentration of vancomycin yields a synergistic antibacterial outcome on E.faecalis strain resistant to vancomycin.展开更多
BACKGROUND: Multidrug resistance is a major obstacle in cancer chemotherapy. We examined whether the antisense RNA of multidrug resistance gene 1 (mdr1) could reverse multidrug resistance in the human hepatocellular c...BACKGROUND: Multidrug resistance is a major obstacle in cancer chemotherapy. We examined whether the antisense RNA of multidrug resistance gene 1 (mdr1) could reverse multidrug resistance in the human hepatocellular carcinoma (HCC) cell line SMMC7721/ADM. METHODS: The recombinant adenoviruses pAdEasy- GFP-ASmdr1 product was produced by the adenoviral vector AdEasy system, which can express antisense RNA against the mdr1 gene. Following that, the recombinant adenovirus was transfected into the P-glycoprotein- producing multidrug resistance cell line, SMMC7721/ADM human HCC cells resistant to adriamycin (ADM) and daunorubicin (DNR). In order to investigate the reversal of multidrug resistance phenotype, we measured the expression of mdr1 mRNA by RT-PCR and the production of P-glycoprotein by flow cytometry. The sensitivities for ADM and DNR SMMC7721/ADM cells were examined by [3-(4, 5-dimethylthi-azol-2-yl)-2,5 diphenyl-terazolium bromide] (MTT) analysis. RESULTS: The low-level expression of mdr1 mRNA and P-glycoprotein production were observed in parental sensitive cells SMMC/7721 in addition to the overexpressionof mdr1 mRNA and P-glycoprotein in SMMC7721/ADM cells. The transfection of antisense-RNA into SMMC7721/ ADM cells resulted in decreases of mdr1 mRNA and P-glycoprotein, but increase of drug sensitivities. The sensitivities of transfected SMMC7721/ADM cells to ADM and DNR in IC50 reduced by 31.25% and 62.96% respectively. CONCLUSIONS: Mdr1 antisense RNA can increase the sensitivities of SMMC7721/ADM cells to anticancer drug by decreasing the expression of the mdr1 gene and inhibiting P-glycoprotein expression. This strategy may be applicable to cancer patients with P-glycoportein mediated multidrug resistance.展开更多
BACKGROUND: Cholecyst cholesterol lithiasis is a common disease of the digestive system; however, the cause of lithogenesis is still unclear. Although bile salt export pump (BSEP), multidrug resistance protein 2 (MRP2...BACKGROUND: Cholecyst cholesterol lithiasis is a common disease of the digestive system; however, the cause of lithogenesis is still unclear. Although bile salt export pump (BSEP), multidrug resistance protein 2 (MRP2), and multiple drug resistance 3 (MDR3 ) are 3 well-known transporting proteins, their effect on lithogenesis has not been elucidated. This study was undertaken to examine the relationship between BSEP, MRP2, MDR3, and cholesterol calculus formation. METHODS: Liver tissue specimens were taken from 20 patients with cholesterol calculus and from 10 patients with normal liver. mRNA and protein expressions of BSEP, MRP2, and MDR3 were determined by reverse tran-scriptase-polymerase chain reaction (RT-PCR) and Western blot, respectively. This study was approved by the ethics committee of China Medical University and informed consent was obtained from all patients. RESULTS: mRNA and protein expressions of BSEP, MRP2, and MDR3 were significantly down-regulated in the liver tissue of the patients with cholesterol calculus compared with normal liver tissue of the controls. CONCLUSION: The down-regulation of BSEP, MRP2, and MDR3 may be correlated with the formation of cholesterol calculus.展开更多
OBJECTIVE: To probe insights into the reversal effect of bufalin on vincristine-acquired multidrug resistance(MDR) in human leukemia cell line K562/VCR.METHODS: Proliferative inhibition rate and the reversal index(RI)...OBJECTIVE: To probe insights into the reversal effect of bufalin on vincristine-acquired multidrug resistance(MDR) in human leukemia cell line K562/VCR.METHODS: Proliferative inhibition rate and the reversal index(RI) of bufalin were determined by Methyl thiazolyl tetrazolium assay. The uptake of Adriamycin(ADM) in K562/VCR cells, cell cycle and apoptosis rate were determined by flow cytometry(FCM). Cell morphologic changes were observed with Wright-Giemsa staining. The expression of P-glycoprotein(P-gp), multidrug-associated protein-1(MRP1), Bcl-x L and Bax protein were measured by immunocytochemistry.RESULTS: The human leukemia multidrug resistant K562/VCR cells showed no cross-resistance to bufalin. The RIs of bufalin at concentrations of 0.0002,0.001 and 0.005 μmol/L were 4.85, 6.94 and 14.77,respectively. Preincubation of 0.001 μmol/L bufalin for 2 h could increase intracellular ADM fluorescence intensity to 28.07%(P<0.05) and down-regulate MRP1 expression simultaneously, but no remarkable effect was found on P-gp protein. Cell cycle analysis indicated increased apoptosis rate and apparent decreased G2/M phase proportion after treatment with bufalin. When exposed to 0.01μmol/L bufalin, typical morphological changes of apoptosis could be observed. Down-regulation of Bcl-x L and up-regulation of Bax expression in K562/VCR cells could be detected by immunocytochemistry.CONCLUSION: Bufalin could partly reverse the MDR of K562/VCR cells, with a possible mechanism of down-regulating MRP1 expression and activating apoptosis pathway by altering Bcl-x L/Bax ratio.展开更多
The expression of multidrug resistant proteins in bladder cancer and clinical implication was studied. Expression of multidrug associated protein (MRP), P glycoprotein (P gp), P53 and Bcl 2 proteins were detected ...The expression of multidrug resistant proteins in bladder cancer and clinical implication was studied. Expression of multidrug associated protein (MRP), P glycoprotein (P gp), P53 and Bcl 2 proteins were detected by using immunohistochemical method in 40 specimens of bladder transitional cell carcinoma. The results showed that the positive rate of MRP, P gp, P53 and Bcl 2 was 52.5 %, 57.5 %, 47.5 % and 62.5 % respectively. The positive rate of MRP, P gp, P53 and Bcl 2 in the grade Ⅰ, Ⅱ and Ⅲ of tumors was 46.3 %, 38.5 %, 38.5 %, 23.1 %; 52.9 %, 39.8 %, 47.1 %, 76.4 %; 60.0 %, 80.0 %, 60.0 %, 90.0 % respectively. The positive rate of MRP, P gp, P53 and Bcl 2 in 24 primary tumor specimens was 37.5 %, 41.7 %, 33.3 %, 45.8 % and that in 16 cases in recurrent specimens receiving chemotherapy 75.0 %, 81.3 %, 68.8 %, 87.5 % respectively. It was suggested the positive rate of MRP, P gp, P53 and Bcl 2 was increased with the advance of tumor grade. The positive rate of four proteins in all recurrent cases was significantly increased ( P <0.05). The expression of MRP, P gp, P53 and Bcl 2 proteins might be the important factors for chemotherapy failure.展开更多
BACKGROUND: The most common mechanisms of mul- tidrug resistance (MDR) in cancer cells is the expression of an energy-dependent exfflux pump. P-glycoprotein (P-gp) encoded by MDR1 gene and multidrug associated protein...BACKGROUND: The most common mechanisms of mul- tidrug resistance (MDR) in cancer cells is the expression of an energy-dependent exfflux pump. P-glycoprotein (P-gp) encoded by MDR1 gene and multidrug associated protein (MRP) are well known proteins associated with MDR. In human cancers, the MDR1 gene expression is common in patients with intrinsic and acquired MDR. It is a major therapeutic problem in cancer chemotherapy. Previously we found that the MDR of HCC is related to MRP gene ex- pression and initiates the intrinsic MDR. The aim of this study is to study the expression of MDR1 gene encoding P-gp and MDR1 mRNA in primary gallbladder carcinoma, and analyze its clinical significance. METHODS: Immunohistochemistry (IHC) S-P method and in situ polymerase chain reaction (ISPCR) were used to detect the expression of P-gp and MDR1 mRNA in 53 cases of untreated primary gallbladder carcinoma and 12 ca- ses of cholecystitis (archival paraffin-embedded tissues). RESULTS: The positive expression rates of P-gp and MDR1 mRNA in the 53 cases and 12 cases were 60.38%, 71.69% and 25.00%, 33.33%, respectively. There was a significant difference between the two groups (P<0.05). The positive expression rate of P-gp and MDRlmRNA were 69.44%, 83.33% and 41.18%, 47.06% respectively in tissues in stage of Nevin against Nevin , (P<0.05). In well, moderately differentiated gallbladder carcinoma tissues, their expressions were 79.49%, 69.23% against 50.00%, 35.71% in low, undifferentiated tissues (P<0.05). CONCLUSIONS: MDR to gallbladder carcinoma is closely related to the intrinsic MDR and it provides an important evidence to reverse the MDR by detection of the MDR1gene. Meanwhile, MDR1 gene expression in gallbladder carcinoma is correlated with some biological characteris- tics , takes part in the carcinogenesis of gallbladder tissues, and acts as a valuable biomarker of prognosis.展开更多
Objective： To study the effect of the extract of Prunella vulgaris L. on multiple drugs resistant bacillus tuberculosis （MDR-TB）. Methods： Experimental animal model in rats was induced by MDR-TB. Normal group mode...Objective： To study the effect of the extract of Prunella vulgaris L. on multiple drugs resistant bacillus tuberculosis （MDR-TB）. Methods： Experimental animal model in rats was induced by MDR-TB. Normal group model group and Prunella vulgaris L. group were set up. The contents of IFN-7, IL-4, IL-10 and IL-12 were examined by ELISA. Their genome mRNAs were extracted, the target genes were amplified by PCR. RT-PCR was used to detect the mRNA levels of them. Results： The content of IFN-q, of the extract of Prunella vulgaris L. group was 1.98±0.67 pg/ml, IL-4 was 6.47±1.46 pg/ml, IL-10 was 12.13±3.43 pg/ml and IL-12 was 3.02±0.86 pg/ml. Compared with the model group, Prunella vulgaris L. group was notable difference in serum IFN-γ, IL-12 and IL-10 （P〈0.05）. The mRNA levels of IFN-γ, IL-12 increased and IL-10 decreased obviously, the differences were quite significant （P〈0.05）, but IL-4 had no obvious change. Conclusion： The extract of Prunella vulgaris L. can enhance the cellar immunological function in rats from up-regulation of the level of genetic transcription, accordingly provide the theory basis of healing of tuberculosis with it.展开更多
Maize seedling blight caused by Fusarium verticillioides is a widely occurring maize disease,but the genetics and mechanisms of resistance are not well understood.In this study,GWAS performed by MLM and 3VmrMLM identi...Maize seedling blight caused by Fusarium verticillioides is a widely occurring maize disease,but the genetics and mechanisms of resistance are not well understood.In this study,GWAS performed by MLM and 3VmrMLM identified 40 and 20 QTNs,associated with seedling blight resistance.These methods identified 49 and 36 genes,respectively.Functional verification of candidate gene ZmSBR1 identified by both methods showed that the resistance of a mutant line to seedling blight decreased by 0.37 grade points after inoculation with F.verticillioides,compared with the WT.The length of the stem rot lesion caused by F.verticillioides increased by 86%in mutant seedlings,and the relative length of the adult plant stalk rot increased by 35%in mutant plants compared to the wild type after inoculation with Fusarium graminearum.Transcriptome analysis showed that expression of defense-related genes after inoculation was down-regulated in the mutant compared to the wild type,synthesis of secondary metabolites associated with resistance was reduced,and the immune response triggered by PAMP decreased,resulting in decreased resistance of mutant maize seedlings.Candidate gene association analysis showed that most maize inbred lines carried the susceptible haplotype.A functional PCR marker was developed.The results demonstrated that ZmSBR1 conferred resistance to multiple Fusarium diseases at the seedling and adult growth stages and had important application value in breeding.展开更多
Multiple drug resistance(MDR)is a tough problem in developing hepatocellular carcinoma(HCC)therapy.Here,we developed TPGS-coated cationic liposomes with Bcl-2 siRNA corona to load doxorubicin(Dox)i.e.,Bcl-2 siRNA/Dox-...Multiple drug resistance(MDR)is a tough problem in developing hepatocellular carcinoma(HCC)therapy.Here,we developed TPGS-coated cationic liposomes with Bcl-2 siRNA corona to load doxorubicin(Dox)i.e.,Bcl-2 siRNA/Dox-TPGS-LPs,to enhance anticancer effect of Dox in HCC-MDR.TPGS i.e.,d-α-tocopheryl polyethylene glycol 1000 succinate,inhibited Pglycoprotein(P-gp)efflux pump and Bcl-2 siRNA suppressed anti-apoptotic Bcl-2 protein.The Bcl-2 siRNA loaded in the liposomal corona was observed under transmission electron microscopy.The stability and hemolysis evaluation demonstrated Bcl-2 siRNA/Dox-TPGSLPs had good biocompatibility and siRNA-corona could protect the liposomal core to avoid the attachment of fetal bovine serum.In drug-resistant cells,TPGS effectively prolonged intracellular Dox retention time and siRNA-corona did improve the internalization of Dox from liposomes.In vitro and in vivo anticancer effect of this dual-functional nanostructure was examined in HCC-MDR Bel7402/5-FU tumor model.MTT assay confirmed the IC50 value of Dox was 20–50 fold higher in Bel7402/5-FU MDR cells than that in sensitive Bel7402 cells.Bcl-2 siRNA corona successfully entered the cytosol of Bel7402/5-FU MDR cells to downregulate Bcl-2 protein levels in vitro and in vivo.Bcl-2 siRNA/Dox-TPGS-LPs showed superior to TPGS-(or siRNA-)linked Dox liposomes in cell apoptosis and cytotoxicity assay in Bel7402/5-FU MDR cells,and 7-fold greater effect than free Dox in tumor growth inhibition of Bel7402/5-FU xenograft nude mice.In conclusion,TPGS-coated cationic liposomes with Bcl-2 siRNA corona had the capacity to inhibit MDR dual-pathways and subsequently improved the anti-tumor activity of the chemotherapeutic agent co-delivered to a level that cannot be achieved by inhibiting a MDR single way.展开更多
INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relatio...INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relationship between expression of multidrugresistance (MDR) phenotype P-glycoprotein (P-gp)and the malignant properties of tumors, but theresults are often conflicting[1-8]. The difference intumor types or MDR phenotype induced by specificagents might account for this discrepancy. Taxotere(TXT), a member of the family of taxanes, hasantitumor activity through its effect of promotingthe polymerization of tubulin[9,10].展开更多
OBJECTIVE:To investigate the phytochemicals and in vitro antioxidant,antimicrobial and cytotoxic potential of Rumex dentatus(R.dentatus)leaf extracts.METHODS:The total phenolics and flavonoids content of R.dentatus ex...OBJECTIVE:To investigate the phytochemicals and in vitro antioxidant,antimicrobial and cytotoxic potential of Rumex dentatus(R.dentatus)leaf extracts.METHODS:The total phenolics and flavonoids content of R.dentatus extracts were evaluated by the Folin-Ciocalteu and aluminum chloride colorimetric methods respectively.Antioxidant potential of studied plant extracts was assessed through 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity,total reducing power and total antioxidant methods.Moreover,antibacterial and antifungal capacity was also evaluated by disc diffusion method against six clinically isolated multi-drug resistant bacterial strains as well as six fungal isolates.Further,cell cytotoxicity was also evaluated through3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay.RESULTS:Ethanol extract showed highest total phenolic[(38.9±1.5)μg gallic acid equivalent/mg]and total flavonoids[(17.2±1.9)μg quercetin equivalent/mg]contents.Antioxidant assays indicated that ethanol and methanol extracts possess potent antioxidant potential.Moreover,it was observed that ethanol and hexane extracts have the potential to inhibit most of the tested multi-drug resistant bacterial strains while methanol,chloroform and hexane extracts could inhibit the growth of pathogenic fungal strains successfully.Among all the studied extracts,ethanolic extract showed highest cytotoxicity against MCF-7 cell line then Hep-2 and DU-145 cell lines by MTT assay with lowest IC50 of 47.3μg/m L.CONCLUSION:These results suggest that R.dentatus could be a potent alternative candidate for treatment of microbial infections and for breast cancer treatment.展开更多
Summary： In order to provide a rational research basis for detection of resistance of Neisseria gonorrhoeae to antimierobial hydrophobie agents and study on the resistant mechanism of multiple transferable resistance...Summary： In order to provide a rational research basis for detection of resistance of Neisseria gonorrhoeae to antimierobial hydrophobie agents and study on the resistant mechanism of multiple transferable resistance （mtr） efflux system, plasmid pET-28a（＋） encoding mtrC gene was constructed and the related target protein was expressed in Escherichia colt （E. cold DE3. The fragments of mtrC gene of Neisseria gonorrhoeae from the standard strains were amplified and cloned into prokaryotic expression plasmid pET-28a（＋） with restriction endonuelease to construct recombinant pET-mtrC which was verified by restriction endonuelease and DNA sequencing. The recom- binant was transformed into E. coli DE3 to express the protein mtrC induced by IPTG. The results showed mtrC DNA fragment was proved correct through restriction endonuelease and DNA sequencing. hs sequence was 99.5 % homologus to that published on GeneBank （U14993）. A 48.5 kD fusion protein which was induced by IPTG was detected by SDS-PAGE. It was concluded that the construction of prokaryotic expression plasmid of mtrC protein of Neisseria gonorrhoeae was correct and the fusion protein was successively expressed in E. coli.展开更多
The multi-radiation of X-rays was investigated with special attention to their energy spectrum in a Mather-type plasma focus device （operated with argon gas）. The analysis is based on the effect of anomalous resista...The multi-radiation of X-rays was investigated with special attention to their energy spectrum in a Mather-type plasma focus device （operated with argon gas）. The analysis is based on the effect of anomalous resistances. To study the energy spectrum, a four-channel diode X-ray spectrometer was used along with a special set of filters. The filters were suitable for detection of medium range X-rays as well as hard X-rays with energy exceeding 30 keV. The results indicate that the anomalous resistivity effect during the post pinch phase may cause multi-radiation of X-rays with a total duration of 300 ± 50 ns. The significant contribution of Cu-Kα was due to the medium range X-rays, nonetheless, hard X-rays with energies greater than 15 keV also participate in the process. The total emitted X-ray energy in the forms of Cu-K and Cu-K/3 was around 0.14 ± 0.02 （J/Sr） and 0.04 ±0.01 （J/Sr）, respectively. The total energy of the emitted hard X-ray （〉 15 keV） was around 0.12± 0.02 （J/Sr）.展开更多
The dynamics of the composition and antibiotic resistance of the fecal coliform bacteria(FCB)in a typical wastewater treatment plant(WWTP)were investigated concerning the seasonal changes.Results showed that WWTP coul...The dynamics of the composition and antibiotic resistance of the fecal coliform bacteria(FCB)in a typical wastewater treatment plant(WWTP)were investigated concerning the seasonal changes.Results showed that WWTP could remove the FCB concentration by 3∼5 logs within the effluent of 10^(4)∼10^(5)CFU/L,but the antibiotic resistant rate of FCB species increased significantly after WWTP.The dominant FCB changed from Escherichia coli in the influent(∼73.0%)to Klebsiella pneumoniae in the effluent(∼53.3%)after WWTP,where the Escherichia coli was removed the most,while Klebsiella pneumoniae was the most persistent.The secondary tank removed the most of FCB(by 3∼4 logs)compared to other processes,but increased all the concerned antibiotic resistant rate.The potential super bugs of FCB community showing resistance to all the target antibiotics were selected in the biological treatment unit of WWTP.The FCB showed the highest multiple antibiotic resistance(92.9%)in total which even increased to 100%in the effluent.Klebsiella has the highest antibiotic resistant rate in FCB,with a multiple antibiotic resistance rate of 98.4%.These indicated that the Klebsiella pneumoniae not just Escherichia coli should be specially emphasized after WWTP concerning the health risk associated with FCB community.展开更多
Theperformanceof a structurally dissipating rock-shed(SDR)depends largely onthecapacityofitsenergy dissipators.At present,mostenergy dissipatorsare made of metals,which dissipateenergy by unrecoverable plastic deforma...Theperformanceof a structurally dissipating rock-shed(SDR)depends largely onthecapacityofitsenergy dissipators.At present,mostenergy dissipatorsare made of metals,which dissipateenergy by unrecoverable plastic deformation.Therefore,they are not able to recover their energy-dissipation capacity after deformation under rockfall impact.However,a rockfall usually disintegrates into pieces when it rolls down from a higher position and results in multiple rockfall impacts.An energy dissipator with self-recovery capability is therefore more suitable for ensuring the safety of SDRs.Replacing metal with polyurethane(a hyperelastic material with remarkable self-recovery capability)can provide self-recovery capability for energy dissipators,making them more suitable for resisting multiple rockfall impacts.In this work,polyurethane was manufactured into twotypes ofenergy dissipators:cylindrical and cubical.Full-scale falling rock impact testsand dynamic numerical simulationswereconducted to study the mechanical response of the energy dissipators.In addition,in order to ensure the accuracy of the simulation,the dynamic mechanical properties of the polyurethanewere tested and its dynamic constitutive model was established.The experimental and simulation tests have clarified the advantages of the polyurethane energy dissipator.We also summarized the practical considerations in the design of energy dissipators.展开更多
Objective: The objective is to study the antibacterial activity of six medicinal plants against two naso-pharyngeal pathogens and determination of total phenol contents in ethanol extracts of those plants. Methods: Di...Objective: The objective is to study the antibacterial activity of six medicinal plants against two naso-pharyngeal pathogens and determination of total phenol contents in ethanol extracts of those plants. Methods: Different serial concentrations (0.05 g/mL, 0.1 g/mL, 0.2 g/mL, 0.4 g/mL) of ethanolic and acetone extracts of Piper nigrum L. (Piperaceae), Ocimum sanctum Linn., Plectranthus amboinicus L. (Lamiaceae), Ayapana triplinervis M.Vahl. (Asteraceae), Cinnamomum zeylanicum L. (Lauraceae), Allium schoenoprasum Linn. (Liliaceace) were evaluated for the antibacterial activity using disc diffusion method against gram positive Streptococcus pyogenes and gram negative Pseudomonas aeruginosa. The extracts were prepared from different parts of the plants. The total phenol content was estimated using folin-ciocaltau reagent in catechol equivalents. Results: Majority of the extracts had inhibitory effect against the tested bacteria at different concentrations. In ethanol extracts, Plectranthus amboinicus exhibited the maximum zone of inhibition (14 mm) at 0.05 g/mL concentration against Streptococcus pyogenes, and Ocimum sanctum showed highest zone of bacterial inhibition (19 mm) at 0.05 g concentration against Pseudomonas aeruginosa. In acetone extracts, Piper nigrum had the maximum zone of bacterial inhibition (17 mm) in 0.4 g/mL concentration against Streptococcus pyogenes and Cinnamomum zeylanicum and Allium schoenoprasum exhibited the highest zone of bacterial inhibition (0.4 g/mL) against Pseudomonas aeruginosa. The ethanol extract of Plectranthus amboinicus contained the highest amount of phenol (0.8 mg/mL) and Allium schoenoprasum contained the lowest amount (0.62 mg/mL). In acetone, Cinnamomum zeylanicum contained highest phenol content (0.78 mg/mL). Conclusion: All these investigations pave way to the molecular modeling of the lead phyto compounds present in the studied plants, and also in finding out their biochemical action in various metabolic pathways and reactions of infection.展开更多
Objective: To investigate the expression of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) and the relationship with cell cycle profiles in ovarian cancer SK-OV-3ip1 multicellular aggregates. ...Objective: To investigate the expression of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) and the relationship with cell cycle profiles in ovarian cancer SK-OV-3ip1 multicellular aggregates. Methods: Liquid overlay system was employed to obtain multicellular aggregates. Expression of P-gp and MRP was detected with flow cytometry (FCM). Outer, intermediate and inner cells from multicellular aggregates were collected by layer-trypsinized method. Cell cycle profiles were also analyzed by FCM. Results: Compared with control cells, no expression of P-gp and MRP was detected in monolyer cells (P=0.128 and P=0.604), but expression of P-gp and MRP in aggregate cells was significantly elevated (P<0.01). P-gp expression in every layer cells was also obviously increased (P<0.01). Furthermore, P-gp expression in every layer cells was also obviously increased (P=0.071). Tendency to increased G0–G1 phase and reduced S phase cells existed from outer through intermediate to inner layers in multicellular aggregates but with no statistical difference. Cell percentages in G2-M phase also had no difference. However, compared with monolayer cells, cells in G0–G1 phase increased and cells in S and G2-M phases lowered significantly in every layer and in the whole multicellular aggregates. Expression elevation of P-gp and MRP was consistent with increased G0–G1 percentage in aggregate cells. Conclusion: Expression of P-gp and MRP increases in cells of SK-OV-3ip1 multicellular aggregates and is consistent with increased G0–G1 percentage, which implies the possible relationship between them and the possible role in multicellular-mediated drug resistance.展开更多
In order to investigate the relationship between the expression of cyclin A and drug resistance in adult patients with acute leukemia (AL), the mRNA expression of cyclin A, mdr1, TopⅡ α , bcl-2 was detected in 6...In order to investigate the relationship between the expression of cyclin A and drug resistance in adult patients with acute leukemia (AL), the mRNA expression of cyclin A, mdr1, TopⅡ α , bcl-2 was detected in 64 adult patients with AL and 20 normal controls by semi-reverse transcription polymerse chain reaction (semi-RT-PCR). It was found that the cyclin A and TopⅡ α mRNA expression levels in drug resistant group were significantly lower than in sensitive group ( P <0.01). Under the same experimental condition no cyclin A mRNA expression was detectable in all normal controls. The mdr1 and bcl-2 mRNA expression levels in resistant group were significantly higher than in sensitive group ( P <0.01). cyclin A and TopⅡ α gene expression levels were closely correlated ( r s =+0.794, P=0.000, n =64) in all AL patients, but cyclin A was not correlated with mdr1 and bcl-2 gene expression levels. In drug resistant group there was a negative correlation between the gene expression levels of cyclin A and mdr1 ( r s =-0.337, P=0.029 ). The 10 AL patients with positive lower expression of both cyclin A and TopⅡ α were all resistant to drugs. Logistic regression of Binary analysis showed the correlation between the lower expression of cyclin A and drug resistance. It was concluded that lower expression of cyclin A gene might be an unfavorable prognostic factor for patients with AL, and detection of both cyclin A and TopⅡ α gene expression would predict drug resistance in AL patients.展开更多
文摘The granular carbides formed from hot deformation in multiple alloying wear resistant cast iron were studied through the observation by means of optical microscope, SEM and TEM. The experimental results show that carbides with large size are formed from original short rhabdoid carbides existing in cast, those with small size directly nucleate in the matrix. Carbides with the size between the above are formed from precipitation induced by hot deformation. The bigger the deformation is, the larger the number of microsized granular carbides is. The mechanisms of nucleation and growth of granular carbides and the function of RE were discussed.
文摘Summary: The expression and functional activity of multiple drug resistance (MDR1) gene in human normal bone marrow CD34+ cells was observed. Human normal bone marrow CD34+ cells were enriched with magnetic cell sorting (MACS) system, and then liposome-mediated MDR1 gene was transferred into bone marrow CD34+ cells. Fluorescence-activated cell sorter was used to evaluate the expression and functional activity of P-glycoprotein (P-gp) encoded by MDR1 gene. It was found that the purity of bone marrow CD34+ cells was approximately (91±4.56) % and recovery rate was (72.3±2.36) % by MACS. The expression of P-gp in the transfected CD34+cells was obviously higher than that in non-transfected CD34+ cells. The amount of P-gp in non-transfected CD34+ cells was (11.2±2.2) %, but increased to (23.6±2.34) % 48 h after gene transfection (P<0.0l). The amount of P-gp was gradually decreased to the basic level one week later. The accumulation and extrusion assays showed that the overexpression of P-gp could efflux Rh-123 out of cells and there was low fluorescence within the transfected cells. The functional activity of P-gp could be inhibited by 10 μg/ml verapamil. It was suggested that the transient and highly effective expression and functional activity of P-gp could be obtained by liposome-mediated MRD1 transferring into human normal bone marrow CD34+ cells.
文摘BACKGROUND The upsurge of antibiotic resistance is a significant challenge to public health,and the dry pipeline of new antibiotics has prompted the discovery of alternative treatment approaches.Enterococcus faecalis(E.faecalis)isolates are often multidrugresistant,posing challenges to antibiotic therapy.Bacteriophage therapy is being explored as an alternative method to treat the growing population of antibioticresistant infections.Nevertheless,many inherent limitations of phages diminish their therapeutic utility,notably the restricted host range and quick development of mutants.The specific types and quantities of bacteriophages and antibiotics may be crucial in generating the optimal phage-antibiotic synergy.AIM To optimize the doses,order,and timing to optimize the synergy of phages and vancomycin on different bacteria states.METHODS A volume of 180μL of E.faecalis bacteria in the logarithmic growth phase,with a concentration of approximately 1×10^(8)colony forming units(CFUs)/mL,was introduced onto a microtitre plate.Subsequently,20μL of phage suspension(1×10^(6)PFUs/mL),vancomycin(16μg/mL),or a combination of both was introduced into the designated wells in the specified sequence and incubated at 37°C for 48 hours.The number of live bacteria was counted at different time points using standardized CFU counting protocols.RESULTS The biofilm model demonstrated that combining phages with vancomycin can eradicate the biofilm.Sequential therapy,involving phage application 8 hours before the antibiotic at a concentration of 108 PFUs/mL,proved the most efficient in eliminating the biofilms and killing the planktonic form of E.faecalis.CONCLUSION The combination of phageɸEFP01 at a higher concentration with a subinhibitory concentration of vancomycin yields a synergistic antibacterial outcome on E.faecalis strain resistant to vancomycin.
基金This study was supported by the grant from National Natural Science Foundation of China (No: 30170925).
文摘BACKGROUND: Multidrug resistance is a major obstacle in cancer chemotherapy. We examined whether the antisense RNA of multidrug resistance gene 1 (mdr1) could reverse multidrug resistance in the human hepatocellular carcinoma (HCC) cell line SMMC7721/ADM. METHODS: The recombinant adenoviruses pAdEasy- GFP-ASmdr1 product was produced by the adenoviral vector AdEasy system, which can express antisense RNA against the mdr1 gene. Following that, the recombinant adenovirus was transfected into the P-glycoprotein- producing multidrug resistance cell line, SMMC7721/ADM human HCC cells resistant to adriamycin (ADM) and daunorubicin (DNR). In order to investigate the reversal of multidrug resistance phenotype, we measured the expression of mdr1 mRNA by RT-PCR and the production of P-glycoprotein by flow cytometry. The sensitivities for ADM and DNR SMMC7721/ADM cells were examined by [3-(4, 5-dimethylthi-azol-2-yl)-2,5 diphenyl-terazolium bromide] (MTT) analysis. RESULTS: The low-level expression of mdr1 mRNA and P-glycoprotein production were observed in parental sensitive cells SMMC/7721 in addition to the overexpressionof mdr1 mRNA and P-glycoprotein in SMMC7721/ADM cells. The transfection of antisense-RNA into SMMC7721/ ADM cells resulted in decreases of mdr1 mRNA and P-glycoprotein, but increase of drug sensitivities. The sensitivities of transfected SMMC7721/ADM cells to ADM and DNR in IC50 reduced by 31.25% and 62.96% respectively. CONCLUSIONS: Mdr1 antisense RNA can increase the sensitivities of SMMC7721/ADM cells to anticancer drug by decreasing the expression of the mdr1 gene and inhibiting P-glycoprotein expression. This strategy may be applicable to cancer patients with P-glycoportein mediated multidrug resistance.
文摘BACKGROUND: Cholecyst cholesterol lithiasis is a common disease of the digestive system; however, the cause of lithogenesis is still unclear. Although bile salt export pump (BSEP), multidrug resistance protein 2 (MRP2), and multiple drug resistance 3 (MDR3 ) are 3 well-known transporting proteins, their effect on lithogenesis has not been elucidated. This study was undertaken to examine the relationship between BSEP, MRP2, MDR3, and cholesterol calculus formation. METHODS: Liver tissue specimens were taken from 20 patients with cholesterol calculus and from 10 patients with normal liver. mRNA and protein expressions of BSEP, MRP2, and MDR3 were determined by reverse tran-scriptase-polymerase chain reaction (RT-PCR) and Western blot, respectively. This study was approved by the ethics committee of China Medical University and informed consent was obtained from all patients. RESULTS: mRNA and protein expressions of BSEP, MRP2, and MDR3 were significantly down-regulated in the liver tissue of the patients with cholesterol calculus compared with normal liver tissue of the controls. CONCLUSION: The down-regulation of BSEP, MRP2, and MDR3 may be correlated with the formation of cholesterol calculus.
基金Shanghai Municipal Health Bureau:Traditional Chinese Medicine in Treating with Advanced Hepatocellular Carcinoma(No.ZYSNXD-CC-ZDYJ032)
文摘OBJECTIVE: To probe insights into the reversal effect of bufalin on vincristine-acquired multidrug resistance(MDR) in human leukemia cell line K562/VCR.METHODS: Proliferative inhibition rate and the reversal index(RI) of bufalin were determined by Methyl thiazolyl tetrazolium assay. The uptake of Adriamycin(ADM) in K562/VCR cells, cell cycle and apoptosis rate were determined by flow cytometry(FCM). Cell morphologic changes were observed with Wright-Giemsa staining. The expression of P-glycoprotein(P-gp), multidrug-associated protein-1(MRP1), Bcl-x L and Bax protein were measured by immunocytochemistry.RESULTS: The human leukemia multidrug resistant K562/VCR cells showed no cross-resistance to bufalin. The RIs of bufalin at concentrations of 0.0002,0.001 and 0.005 μmol/L were 4.85, 6.94 and 14.77,respectively. Preincubation of 0.001 μmol/L bufalin for 2 h could increase intracellular ADM fluorescence intensity to 28.07%(P<0.05) and down-regulate MRP1 expression simultaneously, but no remarkable effect was found on P-gp protein. Cell cycle analysis indicated increased apoptosis rate and apparent decreased G2/M phase proportion after treatment with bufalin. When exposed to 0.01μmol/L bufalin, typical morphological changes of apoptosis could be observed. Down-regulation of Bcl-x L and up-regulation of Bax expression in K562/VCR cells could be detected by immunocytochemistry.CONCLUSION: Bufalin could partly reverse the MDR of K562/VCR cells, with a possible mechanism of down-regulating MRP1 expression and activating apoptosis pathway by altering Bcl-x L/Bax ratio.
文摘The expression of multidrug resistant proteins in bladder cancer and clinical implication was studied. Expression of multidrug associated protein (MRP), P glycoprotein (P gp), P53 and Bcl 2 proteins were detected by using immunohistochemical method in 40 specimens of bladder transitional cell carcinoma. The results showed that the positive rate of MRP, P gp, P53 and Bcl 2 was 52.5 %, 57.5 %, 47.5 % and 62.5 % respectively. The positive rate of MRP, P gp, P53 and Bcl 2 in the grade Ⅰ, Ⅱ and Ⅲ of tumors was 46.3 %, 38.5 %, 38.5 %, 23.1 %; 52.9 %, 39.8 %, 47.1 %, 76.4 %; 60.0 %, 80.0 %, 60.0 %, 90.0 % respectively. The positive rate of MRP, P gp, P53 and Bcl 2 in 24 primary tumor specimens was 37.5 %, 41.7 %, 33.3 %, 45.8 % and that in 16 cases in recurrent specimens receiving chemotherapy 75.0 %, 81.3 %, 68.8 %, 87.5 % respectively. It was suggested the positive rate of MRP, P gp, P53 and Bcl 2 was increased with the advance of tumor grade. The positive rate of four proteins in all recurrent cases was significantly increased ( P <0.05). The expression of MRP, P gp, P53 and Bcl 2 proteins might be the important factors for chemotherapy failure.
文摘BACKGROUND: The most common mechanisms of mul- tidrug resistance (MDR) in cancer cells is the expression of an energy-dependent exfflux pump. P-glycoprotein (P-gp) encoded by MDR1 gene and multidrug associated protein (MRP) are well known proteins associated with MDR. In human cancers, the MDR1 gene expression is common in patients with intrinsic and acquired MDR. It is a major therapeutic problem in cancer chemotherapy. Previously we found that the MDR of HCC is related to MRP gene ex- pression and initiates the intrinsic MDR. The aim of this study is to study the expression of MDR1 gene encoding P-gp and MDR1 mRNA in primary gallbladder carcinoma, and analyze its clinical significance. METHODS: Immunohistochemistry (IHC) S-P method and in situ polymerase chain reaction (ISPCR) were used to detect the expression of P-gp and MDR1 mRNA in 53 cases of untreated primary gallbladder carcinoma and 12 ca- ses of cholecystitis (archival paraffin-embedded tissues). RESULTS: The positive expression rates of P-gp and MDR1 mRNA in the 53 cases and 12 cases were 60.38%, 71.69% and 25.00%, 33.33%, respectively. There was a significant difference between the two groups (P<0.05). The positive expression rate of P-gp and MDRlmRNA were 69.44%, 83.33% and 41.18%, 47.06% respectively in tissues in stage of Nevin against Nevin , (P<0.05). In well, moderately differentiated gallbladder carcinoma tissues, their expressions were 79.49%, 69.23% against 50.00%, 35.71% in low, undifferentiated tissues (P<0.05). CONCLUSIONS: MDR to gallbladder carcinoma is closely related to the intrinsic MDR and it provides an important evidence to reverse the MDR by detection of the MDR1gene. Meanwhile, MDR1 gene expression in gallbladder carcinoma is correlated with some biological characteris- tics , takes part in the carcinogenesis of gallbladder tissues, and acts as a valuable biomarker of prognosis.
基金Supported by the Natural Science Foundation for Universities in Anhui Province (KJ2010A087 and KJ2008A152)
文摘Objective： To study the effect of the extract of Prunella vulgaris L. on multiple drugs resistant bacillus tuberculosis （MDR-TB）. Methods： Experimental animal model in rats was induced by MDR-TB. Normal group model group and Prunella vulgaris L. group were set up. The contents of IFN-7, IL-4, IL-10 and IL-12 were examined by ELISA. Their genome mRNAs were extracted, the target genes were amplified by PCR. RT-PCR was used to detect the mRNA levels of them. Results： The content of IFN-q, of the extract of Prunella vulgaris L. group was 1.98±0.67 pg/ml, IL-4 was 6.47±1.46 pg/ml, IL-10 was 12.13±3.43 pg/ml and IL-12 was 3.02±0.86 pg/ml. Compared with the model group, Prunella vulgaris L. group was notable difference in serum IFN-γ, IL-12 and IL-10 （P〈0.05）. The mRNA levels of IFN-γ, IL-12 increased and IL-10 decreased obviously, the differences were quite significant （P〈0.05）, but IL-4 had no obvious change. Conclusion： The extract of Prunella vulgaris L. can enhance the cellar immunological function in rats from up-regulation of the level of genetic transcription, accordingly provide the theory basis of healing of tuberculosis with it.
基金supported by grants from the National Key Research and Development Program Project of China(2022YFD1201803)Research on Resistance Genetics of Maize Root Rot Disease,State Key Laboratory of Agronomy College,Henan Agricultural University,China(39990073/111)。
文摘Maize seedling blight caused by Fusarium verticillioides is a widely occurring maize disease,but the genetics and mechanisms of resistance are not well understood.In this study,GWAS performed by MLM and 3VmrMLM identified 40 and 20 QTNs,associated with seedling blight resistance.These methods identified 49 and 36 genes,respectively.Functional verification of candidate gene ZmSBR1 identified by both methods showed that the resistance of a mutant line to seedling blight decreased by 0.37 grade points after inoculation with F.verticillioides,compared with the WT.The length of the stem rot lesion caused by F.verticillioides increased by 86%in mutant seedlings,and the relative length of the adult plant stalk rot increased by 35%in mutant plants compared to the wild type after inoculation with Fusarium graminearum.Transcriptome analysis showed that expression of defense-related genes after inoculation was down-regulated in the mutant compared to the wild type,synthesis of secondary metabolites associated with resistance was reduced,and the immune response triggered by PAMP decreased,resulting in decreased resistance of mutant maize seedlings.Candidate gene association analysis showed that most maize inbred lines carried the susceptible haplotype.A functional PCR marker was developed.The results demonstrated that ZmSBR1 conferred resistance to multiple Fusarium diseases at the seedling and adult growth stages and had important application value in breeding.
基金financially supported by National Basic Research Program of China(973 Program,2015CB931802)Natural Science Foundation of China(31470968 and 81627901)。
文摘Multiple drug resistance(MDR)is a tough problem in developing hepatocellular carcinoma(HCC)therapy.Here,we developed TPGS-coated cationic liposomes with Bcl-2 siRNA corona to load doxorubicin(Dox)i.e.,Bcl-2 siRNA/Dox-TPGS-LPs,to enhance anticancer effect of Dox in HCC-MDR.TPGS i.e.,d-α-tocopheryl polyethylene glycol 1000 succinate,inhibited Pglycoprotein(P-gp)efflux pump and Bcl-2 siRNA suppressed anti-apoptotic Bcl-2 protein.The Bcl-2 siRNA loaded in the liposomal corona was observed under transmission electron microscopy.The stability and hemolysis evaluation demonstrated Bcl-2 siRNA/Dox-TPGSLPs had good biocompatibility and siRNA-corona could protect the liposomal core to avoid the attachment of fetal bovine serum.In drug-resistant cells,TPGS effectively prolonged intracellular Dox retention time and siRNA-corona did improve the internalization of Dox from liposomes.In vitro and in vivo anticancer effect of this dual-functional nanostructure was examined in HCC-MDR Bel7402/5-FU tumor model.MTT assay confirmed the IC50 value of Dox was 20–50 fold higher in Bel7402/5-FU MDR cells than that in sensitive Bel7402 cells.Bcl-2 siRNA corona successfully entered the cytosol of Bel7402/5-FU MDR cells to downregulate Bcl-2 protein levels in vitro and in vivo.Bcl-2 siRNA/Dox-TPGS-LPs showed superior to TPGS-(or siRNA-)linked Dox liposomes in cell apoptosis and cytotoxicity assay in Bel7402/5-FU MDR cells,and 7-fold greater effect than free Dox in tumor growth inhibition of Bel7402/5-FU xenograft nude mice.In conclusion,TPGS-coated cationic liposomes with Bcl-2 siRNA corona had the capacity to inhibit MDR dual-pathways and subsequently improved the anti-tumor activity of the chemotherapeutic agent co-delivered to a level that cannot be achieved by inhibiting a MDR single way.
基金Supported in part by phone-Poulenc Rorer Pharmaceuticals INC
文摘INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relationship between expression of multidrugresistance (MDR) phenotype P-glycoprotein (P-gp)and the malignant properties of tumors, but theresults are often conflicting[1-8]. The difference intumor types or MDR phenotype induced by specificagents might account for this discrepancy. Taxotere(TXT), a member of the family of taxanes, hasantitumor activity through its effect of promotingthe polymerization of tubulin[9,10].
文摘OBJECTIVE:To investigate the phytochemicals and in vitro antioxidant,antimicrobial and cytotoxic potential of Rumex dentatus(R.dentatus)leaf extracts.METHODS:The total phenolics and flavonoids content of R.dentatus extracts were evaluated by the Folin-Ciocalteu and aluminum chloride colorimetric methods respectively.Antioxidant potential of studied plant extracts was assessed through 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity,total reducing power and total antioxidant methods.Moreover,antibacterial and antifungal capacity was also evaluated by disc diffusion method against six clinically isolated multi-drug resistant bacterial strains as well as six fungal isolates.Further,cell cytotoxicity was also evaluated through3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay.RESULTS:Ethanol extract showed highest total phenolic[(38.9±1.5)μg gallic acid equivalent/mg]and total flavonoids[(17.2±1.9)μg quercetin equivalent/mg]contents.Antioxidant assays indicated that ethanol and methanol extracts possess potent antioxidant potential.Moreover,it was observed that ethanol and hexane extracts have the potential to inhibit most of the tested multi-drug resistant bacterial strains while methanol,chloroform and hexane extracts could inhibit the growth of pathogenic fungal strains successfully.Among all the studied extracts,ethanolic extract showed highest cytotoxicity against MCF-7 cell line then Hep-2 and DU-145 cell lines by MTT assay with lowest IC50 of 47.3μg/m L.CONCLUSION:These results suggest that R.dentatus could be a potent alternative candidate for treatment of microbial infections and for breast cancer treatment.
文摘Summary： In order to provide a rational research basis for detection of resistance of Neisseria gonorrhoeae to antimierobial hydrophobie agents and study on the resistant mechanism of multiple transferable resistance （mtr） efflux system, plasmid pET-28a（＋） encoding mtrC gene was constructed and the related target protein was expressed in Escherichia colt （E. cold DE3. The fragments of mtrC gene of Neisseria gonorrhoeae from the standard strains were amplified and cloned into prokaryotic expression plasmid pET-28a（＋） with restriction endonuelease to construct recombinant pET-mtrC which was verified by restriction endonuelease and DNA sequencing. The recom- binant was transformed into E. coli DE3 to express the protein mtrC induced by IPTG. The results showed mtrC DNA fragment was proved correct through restriction endonuelease and DNA sequencing. hs sequence was 99.5 % homologus to that published on GeneBank （U14993）. A 48.5 kD fusion protein which was induced by IPTG was detected by SDS-PAGE. It was concluded that the construction of prokaryotic expression plasmid of mtrC protein of Neisseria gonorrhoeae was correct and the fusion protein was successively expressed in E. coli.
文摘The multi-radiation of X-rays was investigated with special attention to their energy spectrum in a Mather-type plasma focus device （operated with argon gas）. The analysis is based on the effect of anomalous resistances. To study the energy spectrum, a four-channel diode X-ray spectrometer was used along with a special set of filters. The filters were suitable for detection of medium range X-rays as well as hard X-rays with energy exceeding 30 keV. The results indicate that the anomalous resistivity effect during the post pinch phase may cause multi-radiation of X-rays with a total duration of 300 ± 50 ns. The significant contribution of Cu-Kα was due to the medium range X-rays, nonetheless, hard X-rays with energies greater than 15 keV also participate in the process. The total emitted X-ray energy in the forms of Cu-K and Cu-K/3 was around 0.14 ± 0.02 （J/Sr） and 0.04 ±0.01 （J/Sr）, respectively. The total energy of the emitted hard X-ray （〉 15 keV） was around 0.12± 0.02 （J/Sr）.
基金supported by the Guangxi Key Research and Development Program(No.AB21196036)the Major science and Technology Project of Nanning(No.20213121)the State Key Joint Laboratory of Environmental Simulation and Pollution Control of China(No.22Z02ESPCR).
文摘The dynamics of the composition and antibiotic resistance of the fecal coliform bacteria(FCB)in a typical wastewater treatment plant(WWTP)were investigated concerning the seasonal changes.Results showed that WWTP could remove the FCB concentration by 3∼5 logs within the effluent of 10^(4)∼10^(5)CFU/L,but the antibiotic resistant rate of FCB species increased significantly after WWTP.The dominant FCB changed from Escherichia coli in the influent(∼73.0%)to Klebsiella pneumoniae in the effluent(∼53.3%)after WWTP,where the Escherichia coli was removed the most,while Klebsiella pneumoniae was the most persistent.The secondary tank removed the most of FCB(by 3∼4 logs)compared to other processes,but increased all the concerned antibiotic resistant rate.The potential super bugs of FCB community showing resistance to all the target antibiotics were selected in the biological treatment unit of WWTP.The FCB showed the highest multiple antibiotic resistance(92.9%)in total which even increased to 100%in the effluent.Klebsiella has the highest antibiotic resistant rate in FCB,with a multiple antibiotic resistance rate of 98.4%.These indicated that the Klebsiella pneumoniae not just Escherichia coli should be specially emphasized after WWTP concerning the health risk associated with FCB community.
基金The research reported in this manuscript was funded by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20030301)the International Partnership Program of the Chinese Academy of Sciences(Grant No.131551KYSB20180042)+1 种基金“Belt&Road”international cooperation team for the“Light of West”program of CAS(Su Lijun),Sichuan Science and Technology Program(Grant No.2021YJ0040)CAS“Light of West China”Program(Grant No.E0R2160).
文摘Theperformanceof a structurally dissipating rock-shed(SDR)depends largely onthecapacityofitsenergy dissipators.At present,mostenergy dissipatorsare made of metals,which dissipateenergy by unrecoverable plastic deformation.Therefore,they are not able to recover their energy-dissipation capacity after deformation under rockfall impact.However,a rockfall usually disintegrates into pieces when it rolls down from a higher position and results in multiple rockfall impacts.An energy dissipator with self-recovery capability is therefore more suitable for ensuring the safety of SDRs.Replacing metal with polyurethane(a hyperelastic material with remarkable self-recovery capability)can provide self-recovery capability for energy dissipators,making them more suitable for resisting multiple rockfall impacts.In this work,polyurethane was manufactured into twotypes ofenergy dissipators:cylindrical and cubical.Full-scale falling rock impact testsand dynamic numerical simulationswereconducted to study the mechanical response of the energy dissipators.In addition,in order to ensure the accuracy of the simulation,the dynamic mechanical properties of the polyurethanewere tested and its dynamic constitutive model was established.The experimental and simulation tests have clarified the advantages of the polyurethane energy dissipator.We also summarized the practical considerations in the design of energy dissipators.
文摘Objective: The objective is to study the antibacterial activity of six medicinal plants against two naso-pharyngeal pathogens and determination of total phenol contents in ethanol extracts of those plants. Methods: Different serial concentrations (0.05 g/mL, 0.1 g/mL, 0.2 g/mL, 0.4 g/mL) of ethanolic and acetone extracts of Piper nigrum L. (Piperaceae), Ocimum sanctum Linn., Plectranthus amboinicus L. (Lamiaceae), Ayapana triplinervis M.Vahl. (Asteraceae), Cinnamomum zeylanicum L. (Lauraceae), Allium schoenoprasum Linn. (Liliaceace) were evaluated for the antibacterial activity using disc diffusion method against gram positive Streptococcus pyogenes and gram negative Pseudomonas aeruginosa. The extracts were prepared from different parts of the plants. The total phenol content was estimated using folin-ciocaltau reagent in catechol equivalents. Results: Majority of the extracts had inhibitory effect against the tested bacteria at different concentrations. In ethanol extracts, Plectranthus amboinicus exhibited the maximum zone of inhibition (14 mm) at 0.05 g/mL concentration against Streptococcus pyogenes, and Ocimum sanctum showed highest zone of bacterial inhibition (19 mm) at 0.05 g concentration against Pseudomonas aeruginosa. In acetone extracts, Piper nigrum had the maximum zone of bacterial inhibition (17 mm) in 0.4 g/mL concentration against Streptococcus pyogenes and Cinnamomum zeylanicum and Allium schoenoprasum exhibited the highest zone of bacterial inhibition (0.4 g/mL) against Pseudomonas aeruginosa. The ethanol extract of Plectranthus amboinicus contained the highest amount of phenol (0.8 mg/mL) and Allium schoenoprasum contained the lowest amount (0.62 mg/mL). In acetone, Cinnamomum zeylanicum contained highest phenol content (0.78 mg/mL). Conclusion: All these investigations pave way to the molecular modeling of the lead phyto compounds present in the studied plants, and also in finding out their biochemical action in various metabolic pathways and reactions of infection.
基金This work was supported by the National Natural Science Foundation of China (No. 30000177).
文摘Objective: To investigate the expression of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) and the relationship with cell cycle profiles in ovarian cancer SK-OV-3ip1 multicellular aggregates. Methods: Liquid overlay system was employed to obtain multicellular aggregates. Expression of P-gp and MRP was detected with flow cytometry (FCM). Outer, intermediate and inner cells from multicellular aggregates were collected by layer-trypsinized method. Cell cycle profiles were also analyzed by FCM. Results: Compared with control cells, no expression of P-gp and MRP was detected in monolyer cells (P=0.128 and P=0.604), but expression of P-gp and MRP in aggregate cells was significantly elevated (P<0.01). P-gp expression in every layer cells was also obviously increased (P<0.01). Furthermore, P-gp expression in every layer cells was also obviously increased (P=0.071). Tendency to increased G0–G1 phase and reduced S phase cells existed from outer through intermediate to inner layers in multicellular aggregates but with no statistical difference. Cell percentages in G2-M phase also had no difference. However, compared with monolayer cells, cells in G0–G1 phase increased and cells in S and G2-M phases lowered significantly in every layer and in the whole multicellular aggregates. Expression elevation of P-gp and MRP was consistent with increased G0–G1 percentage in aggregate cells. Conclusion: Expression of P-gp and MRP increases in cells of SK-OV-3ip1 multicellular aggregates and is consistent with increased G0–G1 percentage, which implies the possible relationship between them and the possible role in multicellular-mediated drug resistance.
文摘In order to investigate the relationship between the expression of cyclin A and drug resistance in adult patients with acute leukemia (AL), the mRNA expression of cyclin A, mdr1, TopⅡ α , bcl-2 was detected in 64 adult patients with AL and 20 normal controls by semi-reverse transcription polymerse chain reaction (semi-RT-PCR). It was found that the cyclin A and TopⅡ α mRNA expression levels in drug resistant group were significantly lower than in sensitive group ( P <0.01). Under the same experimental condition no cyclin A mRNA expression was detectable in all normal controls. The mdr1 and bcl-2 mRNA expression levels in resistant group were significantly higher than in sensitive group ( P <0.01). cyclin A and TopⅡ α gene expression levels were closely correlated ( r s =+0.794, P=0.000, n =64) in all AL patients, but cyclin A was not correlated with mdr1 and bcl-2 gene expression levels. In drug resistant group there was a negative correlation between the gene expression levels of cyclin A and mdr1 ( r s =-0.337, P=0.029 ). The 10 AL patients with positive lower expression of both cyclin A and TopⅡ α were all resistant to drugs. Logistic regression of Binary analysis showed the correlation between the lower expression of cyclin A and drug resistance. It was concluded that lower expression of cyclin A gene might be an unfavorable prognostic factor for patients with AL, and detection of both cyclin A and TopⅡ α gene expression would predict drug resistance in AL patients.
