Identification and Distribution of the Clinical Isolates of Imipenem-resistant Pseudomonas aeruginosa Carrying Metallo-β-lactamase and/or Class 1 Integron Genes

To investigate the distribution of the genes of two major metallo-β-1actamases （MBL;i.e.,IMP and VIM） and class 1 integrons （intI） in the clinical imipenem-resistant Pseudomonas aeruginosa, a total of 65 isolates, from a university hospital in Sichuan between December 2004 and April 2005 were screened for MBL genes by PCR using primers specific for blaIMP-1, blaVIM and blaVIM-2 genes. The MBL-positive isolates were further assessed for class 1 integrons by PCRusing specific primers. The nucleotide sequences of several PCR products were also determined. The results revealed that the blaVIM gene was found in 81.5% （53/65） of all isolates, blaVIM-2 gene was found in only 1 isolate and the intl gene was observed in 45.3% （24/53） of blaVIM-positive isolates. One isolate carried simultaneously both blaIMP-1 and intl genes, and to the best of our knowledge this is the first report of such isolate in southwest China. These observations highlight that the genes for VIM β-1actamase and class 1 integrons were predominantly present among the imipenem-resistant P. aeruginosa tested, confirming the current widespread threat of imipenem-resistant, integron-borne P.aeruginosa.

Occurrence of Extended-Spectrum β-1actamase Producing Enterobacteriaceae （ESBLPE） among Primary School Pupil in Obafemi-Owode, Nigeria

Occurrence of extended-β-1actamase producing enterobacteriaceae （ESBLPE）, which has reduced the antibacterial efficacy and potency of many 3rd generation cephalosporins, was investigated among the primary school pupils. 88 primary school pupils in Obafemi-Owode Local Government, Southwestern Nigeria, including 49 males （55.7%） and 39 females （44,3%） （mean age 12 ± 3） were screened for ESBLPE isolates with exclusion criterion of antimicrobial use in the preceding 2 weeks either as therapy for gastro-intestinal complication or prophylaxis. ESBLPE detected include 4.5% of Eschericia coli, 2.3% of Enterobacter cloaca, 0% Proteus mirabilis, 2.3% Pseudomonas aeruginosa, 1.1% Staphylococcus aureus and 4.5% of Klebsiella oxytoca. 10 （76.9%） of ESBLPE isolates were resistant to disc of cefuroxime （30 μg）, 8 （61.5%） susceptible to amoxicillin/clavulanic （20/10 lag） and low susceptibility of 7 （53.8%） was recorded for ceftazidime （30 lag）. 0% susceptibility was recorded for the ESBLPE isolates to cefuroxime MIC 〉 8 gg/mL and ampicillin MIC 〉 8 lag/mL while E, coli and E. cloca each show 50.0% and P. aeruginosa and K. oxytoca show 100.0% and 75.0% susceptibility to augmentin （MIC 〈 8）. This study has shown a 14.7% proportion of the pupil to harbour ESBLPE from enteric source with increased resistant to most new generation cefuroximes. Therefore, transfer of virulent and antibiotic resistant ESBLPE could be aided by sharing feeding materials while fecal-oral route of transmission cannot be ruled out as hygiene level is very low thereby increasing emergence of virulent resistant enteric strains leading to treatment failure.

Targeted anti-cancer therapy: Co-delivery of VEGF siRNA and Phenethyl isothiocyanate (PEITC) via cRGD-modified lipid nanoparticles for enhanced anti-angiogenic efficacy

Anti-tumor angiogenesis therapy, targeting the suppression of blood vessel growth in tumors, presents a potent approach in the battle against cancer. Traditional therapies have primarily concentrated on single-target techniques, with a specific emphasis on targeting the vascular endothelial growth factor, but have not reached ideal therapeutic efficacy. In response to this issue, our study introduced a novel nanoparticle system known as CS-siRNA/PEITC&L-cRGD NPs. These chitosan-based nanoparticles have been recognized for their excellent biocompatibility and ability to deliver genes. To enhance their targeted delivery capability, they were combined with a cyclic RGD peptide (cRGD). Targeted co-delivery of gene and chemotherapeutic agents was achieved through the use of a negatively charged lipid shell and cRGD, which possesses high affinity for integrin αvβ3 overexpressed in tumor cells and neovasculature. In this multifaceted approach, co-delivery of VEGF siRNA and phenethyl isothiocyanate (PEITC) was employed to target both tumor vascular endothelial cells and tumor cells simultaneously. The co-delivery of VEGF siRNA and PEITC could achieve precise silencing of VEGF, inhibit the accumulation of HIF-1α under hypoxic conditions, and induce apoptosis in tumor cells. In summary, we have successfully developed a nanoparticle delivery platform that utilizes a dual mechanism of action of anti-tumor angiogenesis and pro-tumor apoptosis, which provides a robust and potent strategy for the delivery of anti-cancer therapeutics.

The transverse laser induced thermoelectric voltages in step flow growth (1-x)Pb(Mg_(1/3)Nb_(2/3))O_(3-x)PbTiO_3 thin films

This paper reports that the transverse laser induced thermoelectric voltages （LITV） axe observed for the first time in the step flow growth （1- x）PD（Mg1/3Nb2/3）O3-xPbTiO3 （PMN-PT, x = 0.20, 0.33, 0.50） thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate （PMN） and lead titanate （PT）, there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength, the largest induced voltage is observed in the 0.50Pb（Mg1/3Nb2/3）O3-0.50 PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.

The Intramolecular Coupling Reaction of 1,6-Bis(1-Alky1-2-Methylindol-3-yl)hexane-1,6-dione Induced by Low-valent Titanium

The intramolecular reductive coupling reaction of 1,6-bis(subshtuted indolyl)hexane-1,6-dione using zero-valent titanium reagent as catalyst proderes the novel photochromic 1,2-diheterocyclic cyclohexenes 2, together with unexpected compounds 3

Anti-tumor effects induced by gene vaccines co-expressing truncated human prostate specific membrane antigen gene and mouse 4-1BBL

Objective To investigate the influence of m4-1BBL on anti-tumor effects induced by truncated human prostate specific membrane antigen ( tPSMA ) gene in mice. Methods A eukaryotic expression plasmid encoding tPSMA and m4-1BBL ( pDC316-tPSMA-IRES m4-1BBL) ,pDC316-tPSMA and pDC316 were constructed.

蕨麻正丁醇部位下调缺氧内皮细胞HIF-1α及ET-1表达

[目的]探讨蕨麻正丁醇部位对内皮细胞缺氧损伤的保护机制。[方法]采用人脐静脉内皮细胞(EA.hy926)建立缺氧损伤实验模型,实验设常氧对照组、缺氧模型组、高(3.00 g/L)、中(1.50 g/L)、低浓度(0.75 g/L)蕨麻正丁醇部位组,复方丹参(3.0 g/L)组。胎盘兰染色法测定各组细胞存活率;逆转录-聚合酶链反应(RT-PCR)技术检测各组缺氧诱导因子-1α(HIF-1α)m RNA和内皮素-1(ET-1)m RNA表达,免疫细胞化学染色及Western Blot方法检测HIF-1α蛋白表达。放免法测定培养基中ET-1的活性。[结果]与对照组比较,缺氧模型组细胞存活率显著降低,HIF-1α和ET-1m RNA及蛋白表达增加(P<0.01);蕨麻正丁醇部位各剂量组与缺氧模型组比较,细胞存活率显著升高,高、中、低剂量蕨麻正丁醇部位组、复方丹参组细胞HIF-1α和ET-1 m RNA及蛋白水平显著降低(P<0.01)。[结论]在缺氧状态下,蕨麻正丁醇部位可能通过HIF-1α途径调控靶基因的表达,从而发挥保护作用。

Total Alkaloids from Sophora Alopecuroides L.Increase Susceptibility of Extended-Spectrum β-Lactamases Producing Escherichia coli Isolates to Cefotaxime and Ceftazidime

Objective： To evaluate the antimicrobial activity of total alkaloids extracted from Sophorea alopecuroides L. （TASA） against clinical isolated extended-spectrum beta-lactamases （ESBLs） producing Escherichia coil （E.. coil） strains. Methods： The antibacterial activity of TASA either itself or in combination with cefotaxime （CTX） or ceftazidime （CAZ） was investigated by using the microbroth dilution method and phenotypic confirmatory disk diffusion test against three clinical isolated ESBLs-producing E. coil strains; the interactions of TASA and C＇I＇X or CAZ were ascertained by evaluating the fractional inhibitory concentration index （FICI）. Results： The antibacterial activity of either TASA itself or in combination with C＇IX or CAZ was found. The minimum inhibitory concentration （MICs） of TASA against the ESBLs producing isolates was 12.5 mg/mL. In the combinations with a sub-inhibitory concentration of TASA, a synergistic effect on CTX and CAZ against the ESBLs producing isolates was observed. Similarly, the isolates exposed to lower dose of TASA yielded an increased susceptibility to CTX and CAZ by 8-16 folds determined by microdilution assay. Moreover, enzymatic detection of ESBLs demonstrated that TASA induced reversal resistance to CTX and CAZ partially by a mechanism of inhibition of ESBLs activity in these isolates. Additionally, in the tested isolates following the exposure of TASA, molecular analysis verified the SHV-type beta-lactamase encoding ESBL gene in these isolates, and no mutation was introduced into the ESBL gene. Conclusions： These results suggest that TASA could be used as a source of natural compound with pharmacological activity of reversal resistance to antimicrobial agent. These findings also indicated that the application of the TASA in combination with antibiotics might prove useful in the control and treatment of infectious diseases caused by the ESBLs producing enterobacteriaceae.

脯氨酸羟化酶抑制剂对小鼠间充质干细胞的动员作用

[目的]探讨脯氨酸羟化酶抑制剂——二甲基乙二酰基甘氨酸(dimethyloxaloylglycine,DMOG)对小鼠间充质干细胞(mouse mesenchymal stem cells,mMSCs)的动员作用。[方法]ICR小鼠随机分为对照组及3个DMOG动员剂量组(20、40、80mg·kg-1)。不同剂量的DMOG每天一次在固定的时间段腹腔内注射入ICR小鼠,对照组给予相同体积的生理盐水。采用流式细胞术与成纤维细胞集落形成单位法检测不同浓度DMOG处理后小鼠外周血与骨髓中MSCs数量,Western blotting法检测骨髓细胞中HIF-1α、SDF-1α及VEGF蛋白的表达,ELISA法检测骨髓上清及外周血清中SDF-1α及VEGF蛋白的浓度。[结果]流式细胞术与成纤维细胞集落形成单位法检测发现不同剂量的DMOG处理7d后小鼠外周血与骨髓中MSCs数量较对照组显著增加(P<0.05),且CD45-CD90+细胞群比例升高(P<0.05)。同时Western blotting法及ELISA法检测发现小鼠骨髓HIF-1α、SDF-1α表达上调,VEGF浓度升高(P<0.05)。[结论]DMOG对小鼠间充质干细胞具有动员作用,可能与通过上调HIF-1α,从而调控其下游相关通路有关。

缺氧对人胃癌细胞HIF-1α及DEC1表达的影响

目的研究缺氧对人胃癌细胞株BGC823缺氧诱导因子-1α(HIF-1α)及分化型胚胎软骨发育基因1(DEC1)表达的影响。方法将细胞株BGC823分为实验组(缺氧24 h组、缺氧48 h组)、对照组(常氧24 h组、常氧48 h组)和阴性对照组(PBS作为一抗)。实验组置于5%CO2、0.5%O2缺氧培养箱培养,对照组于37℃、5%CO2的培养箱中培养。用RT-PCR及Western blotting的方法检测两组细胞HIF-1α与DEC1各水平的表达。另外,用免疫细胞化学的方法进一步检测HIF-1α与DEC1的表达并进行相关性分析。结果缺氧处理后,HIF-1α和DEC1的mRNA和蛋白表达水平均明显高于对照组(P<0.05)。HIF-1α及DEC1 mRNA表达水平随缺氧时间增加而上升,HIF-1α及DEC1蛋白表达水平随缺氧时间增加而下降。实验组HIF-1α及DEC1阳性率明显高于对照组(P<0.05)。结论缺氧条件下,胃癌细胞株BGC823中HIF-1α、DEC1各水平的表达增加,二者具有显著相关性。缺氧可能通过诱导HIF-1α的大量表达,转录激活DEC1的表达。DEC1作为HIF-1α的下游靶基因,在胃癌细胞适应缺氧环境中发挥重要作用。

Development of a colorimetric assay for rapid quantitative measurement of clavulanic acid in microbial samples

We developed a colorimetric assay to quantify clavulanic acid （CA） in culture broth of Streptomyces clavuligerus, to facilitate screening of a large number of S. clavuligerus mutants. The assay is based on a β-1actamase-catalyzed reaction, in which the yellow substrate nitrocefin （λmax=390 nm） is converted to a red product （λmax=486 nm）. Since CA can irreversibly inhibit β-1actamase activity, the level of CA in a sample can be measured as a function of the A390]A486 ratio in the assay mixture. The sensitivity and detection window of the assay were determined to be 50 μg L -1 and 50 μg L to 10 mg L-1, respectively. The reliability of the assay was confirmed by comparing assay results with those obtained by HPLC. The assay was used to screen a pool of 65 S. clavuligerus mutants and was reliable for identifying CA over-producing mutants. Therefore, the assay saves time and labor in large-scale mutant screening and evaluation tasks. The detection window and the reliability of this assay are markedly better than those of previously reported CA assays. This assay method is suitable for high throughput screening of microbial samples and allows direct visual observation of CA levels on agar plates.