矾冰纳米乳对临床常见病原菌体外抗菌活性的研究

研究纳米化提高白矾与冰片复合物体外抗菌活性的效果。分别采用琼脂扩散法、体外杀菌试验及试管稀释法,测定白矾与冰片O/W型复合纳米乳对临床常见病原菌的体外抑菌、杀菌效果及最低抑菌浓度(MIC),实验中以等浓度矾冰液作为对照。结果显示,矾冰纳米乳对金黄色葡萄球菌、表皮葡萄球菌、大肠埃希菌、铜绿假单胞菌、白假丝酵母菌的抑制及杀灭活性均明显强于矾冰液(P0.05)。矾冰纳米乳对金黄色葡萄球菌、铜绿假单胞菌、大肠埃希菌临床菌株MIC90值分别为1.02、2.04和2.04 mg/mL,均明显低于矾冰液的MIC90值(P0.05)。上述实验结果提示,矾冰纳米乳与矾冰液均有广谱体外抑菌及杀菌活性,白矾及冰片复合物纳米化可提高抗菌效果。     

假丝酵母菌尿路感染临床观察及耐药性分析

目的 调查和分析尿路感染假丝酵母菌的分布及耐药情况,为临床合理选用抗菌药物提供依据.方法 尿液采用经典型浸片Uricult培养,使用ATB-Fungus板条进行药敏试验,利用WHONET 5.6对浙江萧山医院2008年1月至2012年12月间尿培养分离菌株及药敏结果进行回顾性分析.结果 共分离出假丝酵母菌273株,其中白假丝酵母菌占37.4％,光滑假丝酵母菌28.9％、热带假丝酵母菌27.8％;临床分离数量以ICU(58)最多,其次为泌尿外科(50)和内科(49).药敏结果显示:两性霉素B、5-氟胞嘧啶对白假丝酵母菌、热带假丝酵母菌和光滑假丝酵母菌仍保持较强的抗菌活性,敏感率≥98.6％,伏立康唑敏感率≥86.3％.结论 尿路感染分离得到的假丝酵母菌以白假丝酵母菌为主,其次为光滑假丝酵母菌和热带假丝酵母菌;两性霉素B、5-氟胞嘧啶对假丝酵母菌保持较强的抗菌活性,是治疗假丝酵母菌感染的首选药物.临床应重视假丝酵母菌的培养和其药敏试验,根据药敏结果科学合理使用抗真菌药物.     

甲磺酸培氟沙星抑制大肠杆菌RecQ解旋酶的体外DNA结合、解链和ATPase活性

RecQ家族解旋酶是DNA解旋酶中高度保守的一个重要家族,参与DNA复制、修复、重组、转录及维持端粒稳定等细胞代谢过程,在维持染色体稳定性与完整性中起着重要作用．甲磺酸培氟沙星(pefloxacin mesylate,PFM)是一种新型氟喹诺酮类抗菌药物,对一些革兰氏阴性菌具有明显的杀菌效果,临床上已广泛使用．本研究利用荧光偏振、自由磷检测技术研究PFM对大肠杆菌RecQ解旋酶的DNA结合活性、解链活性、ATPase活性的影响．结果表明,低浓度PFM可促进大肠杆菌RecQ解旋酶与ssDNA、dsDNA结合,达到一定量后PFM则抑制酶与DNA底物的结合,这种影响与DNA底物有关;PFM对RecQ解旋酶的DNA解链活性和ATP酶活性都具有抑制作用,但其抑制的效果有极显著差异(P<0.01)：比较PFM对两种活性抑制的Ci值(对解链活性抑制的Ci值为(1.5±0.2) μmol/L,对ATP酶活性抑制的Ci值为(0.010±0.005) μmol/L)可知,PFM对大肠杆菌RecQ解旋酶ATPase活性的抑制强于其解链活性. 这些结果可为研究以DNA解旋酶为药物靶标的分子机理奠定相关理论基础．     

猪脱细胞真皮基质与RV-23抗菌肽复合材料的制备及生物学特性初步研究

目的:制备低免疫原性猪脱细胞真皮基质(PADM)与抗菌肽RV-23的复合材料,并对其生物学特性进行初步评价。方法:将抗菌肽RV-23分别以1、5、20μmol/L的浓度加到直径6 mm、厚约1 mm的低免疫原性PADM上,制备复合材料;菌落计数分析实验检测复合材料的抗菌能力;溶血实验检测复合材料对红细胞膜的裂解能力;CCK-8实验检测复合材料对真核细胞的细胞毒性;Tricine-SDS-PAGE检验RV-23的稳定性。结果:制备了PADM与抗菌肽RV-23复合材料;活菌计数实验表明复合材料对大肠杆菌有很强的抗菌活性,并随着抗菌肽浓度的升高不断增强;溶血实验表明PADM能有效降低RV-23裂解红细胞膜的能力,增加血液相容性;CCK-8实验显示PADM能够有效降低RV-23的细胞毒性,复合材料对人表皮角化细胞HaCaT和小鼠成纤维细胞NIH-3T3几乎没有毒性;Tricine-SDSPAGE实验结果显示复合材料抗菌肽RV-23稳定性较好。结论:PADM/RV-23复合材料比较稳定,不仅具有较强的抗菌性,而且有良好的血液相容性和极低的细胞毒性,有望成为新型创伤修复材料。     

20种药用蕨类植物提取液抑菌试验研究

以20种药用蕨类植物提取液对金黄色葡萄球菌、大肠杆菌、八叠球菌、变形杆菌、枯草杆菌、酵母菌进行抑菌活性研究,结果表明,20种蕨类提取液至少对一种供试微生物具有抑菌活性。样品蕨类醇提液比水提液具更强的抑菌活性,供试菌有阳性结果的水提液,平均抑菌圈直径10.12mm,而醇提液则为11.92mm。试验结果还表明,药用蕨类对枯草杆菌抗菌活性效果最明显,对酵母菌效果最差。不同蕨类植物其地上部分和地下部分抑菌效果不尽相同。     

纳米银的抗菌机制及临床应用研究

纳米银因具备抗菌谱广、效果好、安全性高等特性,其医疗制品在临床治疗方面应用广泛。现普遍认为纳米银可通过释放银离子(Ag⁺)和诱导活性氧自由基的表达等方式达到杀菌目的,但其发挥抗菌作用的效果受到表面正电荷和粒子直径等因素影响。本文就纳米银的抗菌机制及临床实践应用进行综述,对现有的各种抗菌材料进行分类,重点探讨纳米银对金黄色葡萄球菌、大肠埃希菌、白假丝酵母菌和铜绿假单胞菌的杀菌和抑菌原理,以及其在抗菌过程中的影响因素,并阐述了纳米银及其复合材料在临床实践中的应用,以期为纳米银抗菌应用方面的后续研究提供一些参考。     

橙盖鹅膏多糖(AC-1)体外免疫调节活性、细胞毒性和抗肿瘤活性的研究

为研究橙盖鹅膏多糖的体外免疫调节活性、细胞毒性和抗肿瘤活性,本研究运用细胞学技术探究AC-1对T细胞、B细胞和RAW264.7三种免疫细胞的体外免疫调节活性;研究AC-1对小鼠成纤维细胞(L929)的细胞毒性以及对小鼠胃癌细胞(MFC)、小鼠肉瘤细胞(S180)的体外抗肿瘤活性。结果表明,AC-1能在体外显著刺激三种免疫细胞的增殖及RAW264.7细胞的吞噬,表明AC-1在增强机体免疫方面具有重要作用,进一步研究发现AC-1主要通过显著促进IgE和IgG的分泌来增强体液免疫。在浓度为5~20μg/mL时AC-1对L929细胞无显著的促进及抑制作用,说明AC-1对正常细胞无毒性;在浓度为10~20μg/mL时AC-1能显著抑制小鼠胃癌细胞(MFC)的生长,但对小鼠肉瘤细胞(S180)的抑制效果较弱,说明AC-1在体外能够直接抑制肿瘤细胞的生长,但对不同的肿瘤细胞具有不同的抑制效果。综上所述,橙盖鹅膏多糖(AC-1)在体外具有良好的免疫调节活性、抗肿瘤活性,但对不同的肿瘤细胞具有不同的抑制效果并且对正常细胞无毒性。     

10种抗生素对厌氧菌体外抗菌活性的研究

本研究采用琼脂平板稀释法测定了6种抗生素对105株临床分离厌氧菌及4种临床常用抗生素对分离的50株类杆菌体外抗菌活性。结果表明:氯林可霉素对所有试验菌株均具极强的抗菌活性,MIC_(90)不超过0.78μg/ml。甲硝唑对类杆菌和梭菌也有很强的抗菌活性,MIC_(90)分别为3.13μg/ml和0.78μg/ml,但对其它种厌氧菌的抗菌活性不强。头孢唑肟、氧哌嗪青霉素对试验菌株的MIC_(50)较小,但对部分菌株的MIC_(90)为25μg/ml,抗厌氧菌的活性有限。头孢噻肟和头孢噻甲羧肟对各类厌氧菌以及头孢噻啶、头孢唑啉、氨苄青霉素和羧苄青霉素对类杆菌的抗菌活性均很弱。     

山苍子油对白假丝酵母抗菌活性研究

研究山苍子油对白假丝酵母菌的抗菌活性,并阐明其可能的抗菌机制。通过水蒸馏法提取山苍子油,并利用气相色谱-质谱联用仪(GC/MS)分析其成分。通过琼脂平板稀释法测定山苍子油对白假丝酵母的最低抑菌浓度(MIC)和最低杀菌浓度(MFC),并研究山苍子油对白假丝酵母的抗菌动力学;同时利用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察山苍子油对白假丝酵母细胞超微结构的影响。结果表明,自提山苍子油主成分为柠檬烯(26.51%),柠檬醛(11.94%)和马鞭烯醇(11.84%)。山苍子油对白假丝酵母菌的MIC和MFC均为1.25μL/m L;其抗菌动力学研究表明浓度低于其MIC时,山苍子油仅延长白假丝酵母的生长适应期,并不能彻底杀死细胞;SEM结果表示,山苍子易破坏正在出芽的细胞;TEM显示出山苍子破坏细胞壁,细胞膜,使细胞裂解。山苍子油具有优良的抗白假丝酵母活性,且白假丝酵母在芽痕处对山苍子油比较敏感,高浓度的精油(5.0μL/m L)对细胞产生不可逆破坏;山苍子油杀菌的靶标可能是细胞壁和细胞外膜,使细胞内大分子外泄,细胞器变形,最终导致细胞死亡。     

人HMGB1酸性尾端对其抗菌活性的影响

为研究人高迁移率族蛋白B1(high-mobility group box-1HMGB1)酸性尾端对其抗菌活 性的影响,提取人外周血单个核细胞总RNA,经RT\|PCR扩增得到编码人HMGB1的cDNA及其缺失酸性尾端的突变体cDNA(mcDNA),原核表达载体pQE\|80L分别表达重组人HMGB1蛋白(rhHMGB1)及缺失酸性尾端的突变体蛋白(mrhHMGB1),经Ni^2+_- NTA亲和层析柱纯化两种蛋白.通过试管稀释法、琼脂扩散法两种体外抗菌实验观察,并比较rhHMGB1mrhHMGB1抗菌活性的差异.实验结果显示,rhHMGB1对大肠杆菌JM109、ATCC2592 2、DH5α有明确的抗菌活性,其抗菌活性强弱依次为JM109>ATCC25922>DH5α,而mrhHMGB1 对大肠杆菌JM109、ATCC25922、DH5α则均无抗菌活性.实验结果表明,人HMGB1的酸性尾端对其抗菌活性的发挥至关重要,此研究为进一步探讨人HMGB1抗菌功能的机制奠定了基础.     

纳米氧化锌和接种丛枝菌根真菌对大豆生长及营养吸收的影响

纳米氧化锌是应用最广的人工纳米颗粒(nanoparticles,NPs)之一,具有一定生物毒性。丛枝菌根(arbuscular mycorrhizal,AM)真菌能与陆地上80%以上的高等植物形成丛枝菌根共生体,并能改善宿主植物矿质营养,提高其抗逆性。然而纳米ZnO与丛枝菌根的关系尚不清楚。通过温室沙培盆栽试验,研究了施加不同水平纳米ZnO(0、500、1000、2000、3000 mg/kg)和接种AM真菌Acaulospora mellea对大豆生长及营养状况的影响。结果表明,3000 mg/kg的纳米ZnO显著抑制大豆植株生长,表现出植物毒性,在其他水平时没有显著影响。纳米ZnO在施加水平500、1000 mg/kg时没有抑制AM真菌对大豆根系的侵染,但是高施加水平(2000 mg/kg)时对AM真菌产生毒害,几乎完全抑制大豆根系菌根侵染。接种AM真菌仅在500 mg/kg纳米ZnO时显著促进大豆生长,增加大豆植株对P、K、N的吸收,降低根系Zn含量。纳米ZnO可能会持续释放锌离子,并抑制大豆根系对矿质营养元素的吸收,从而产生生物毒性,而AM真菌与大豆根系的共生可起到有益作用。     

Synthesis and characterization of chitosan/ZnO nanoparticle composite membranes

Novel chitosan/ZnO nanoparticle (CS/nano-ZnO) composite membranes were prepared via the method of sol-cast transformation and studied by UV-vis absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray fluorescence spectrometry (EDX). The characterization revealed that ZnO nanoparticles dispersed homogeneously within the chitosan matrix. The mechanical and antibacterial properties of the product were investigated. The results showed that the ZnO content had an effect on the mechanical properties of CS/nano-ZnO composite membranes, and that the antibacterial activities of CS membranes for Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were enhanced by the incorporation of ZnO. Further, CS/nano-ZnO composite membranes with 6-10 wt % ZnO exhibited high antibacterial activities.     

Titanium dioxide particles phosphorylate histone H2AX independent of ROS production

Zinc oxide (ZnO) nanoparticles are finding applications in a wide range of products including cosmetics, food packaging, imaging, etc. This increases the likelihood of human exposure to these nanoparticles through dermal, inhalation and oral routes. Presently, the majority of the studies concerning ZnO nanoparticle toxicity have been conducted using in vitro systems which lack the complex cell-cell, cell-matrix interactions and hormonal effects found in the in vivo scenario. The present in vivo study in mice was aimed at investigating the oral toxicity of ZnO nanoparticles. Our results showed a significant accumulation of nanoparticles in the liver leading to cellular injury after sub-acute oral exposure of ZnO nanoparticles (300 mg/kg) for 14 consecutive days. This was evident by the elevated alanine aminotransferase (ALT) and alkaline phosphatase (ALP) serum levels and pathological lesions in the liver. ZnO nanoparticles were also found to induce oxidative stress indicated by an increase in lipid peroxidation. The DNA damage in the liver and kidney cells of mice was evaluated by the Fpg-modified Comet assay which revealed a significant (p<0.05) increase in the Fpg-specific DNA lesions in liver indicating oxidative stress as the cause of DNA damage. The TUNEL assay revealed an induction of apoptosis in the liver of mice exposed to ZnO nanoparticles compared to the control. Our results conclusively demonstrate that sub-acute oral exposure to ZnO nanoparticles in mice leads to an accumulation of nanoparticles in the liver causing oxidative stress mediated DNA damage and apoptosis. These results also suggest the need for a complete risk assessment of any new engineered nanoparticle before its arrival into the consumer market.     

Sodium alginate/poly(vinyl alcohol)/nano ZnO composite nanofibers for antibacterial wound dressings

Sodium alginate (SA)/poly (vinyl alcohol) (PVA) fibrous mats were prepared by electrospinning technique. ZnO nanoparticles of size ∼160 nm was synthesized and characterized by UV spectroscopy, dynamic light scattering (DLS), XRD and infrared spectroscopy (IR). SA/PVA electrospinning was further carried out with ZnO with different concentrations (0.5, 1, 2 and 5%) to get SA/PVA/ZnO composite nanofibers. The prepared composite nanofibers were characterized using FT-IR, XRD, TGA and SEM studies. Cytotoxicity studies performed to examine the cytocompatibility of bare and composite SA/PVA fibers indicate that those with 0.5 and 1% ZnO concentrations are less toxic where as those with higher concentrations of ZnO is toxic in nature. Cell adhesion potential of this mats were further proved by studying with L929 cells for different time intervals. Antibacterial activity of SA/PVA/ZnO mats were examined with two different bacteria strains; Staphylococcus aureus and Escherichia coli, and found that SA/PVA/ZnO mats shows antibacterial activity due to the presence of ZnO. Our results suggest that this could be an ideal biomaterial for wound dressing applications once the optimal concentration of ZnO which will give least toxicity while providing maximum antibacterial activity is identified.f     

Toxicological studies of the carbamates methomyl and bendiocarb in the bulb mite Rhizoglyphus echinopus (Acari: Acaridae)

Methomyl was 15 and 31.3 times more toxic than bendiocarb to bulb mites at the LC50 and LC90 values respectively. However, methomyl (pI50 3.0) was at least 126 times less active than bendiocarb (pI50 5.1) as an inhibitor of bulb mite cholinesterase in vitro. The disparity between the high toxicity of methomyl and its extremely low activity as an inhibitor of mite cholinesterase in vitro indicated that another mechanism was likely involved in its toxic action. Pharmacokinetic studies of methomyl and bendiocarb showed that penetration and metabolism were rapid and that there were no substantial differences in the internal levels of the respective parent carbamates during the 24 h test period. However, volatile radioactive material(s), some of which was carbon dioxide, was produced in appreciably greater amounts from methomyl than from bendiocarb. We speculate that the production of volatiles, such as carbon dioxide, acetonitrile and/or methylamine, may contribute to the toxicity of methomyl to bulb mites. © Rapid Science Ltd. 1998     

Nanosized flower-like ZnO synthesized by a simple hydrothermal method and applied as matrix for horseradish peroxidase immobilization for electro-biosensing

Nanosized flower-like ZnO was synthesized by a simple hydrothermal method which is a convenient, environment friendly, inexpensive and efficient process. Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to confirm the material structure and the crystallite microstructure. Then ZnO was dispersed in the chitosan solution to form a ZnO/chitosan composite matrix for the fabrication of H2O2 biosensor. This composite combined the advantages of inorganic species (ZnO) and organic polymer (chitosan). The parameters affecting the fabrication and experimental conditions of biosensors were optimized. Using hydroquinone as the mediator, the biosensor showed a fast response of less than 5s with the linear range of 1.0x10(-5) to 1.8x10(-3) M H2O2 with a correlation coefficient of 0.995 (n=20). The detection limit of the sensor was found to be 2.0 microM, based on a signal-to-noise ratio of 3. The biosensor exhibited satisfactory reproducibility and stability and retained about 78% of its original response after 40 days storage in a phosphate buffer at 4 degrees C.     

Interfacing myoglobin to graphite electrode with an electrodeposited nanoporous ZnO film

A biocompatible, nanoporous ZnO film was prepared on graphite electrode by the simple electrodeposition method. Based on the film's strong adsorption ability and friendly microenvironment, it can be used as a good matrix to immobilize myoglobin (Mb) through simple adsorption. Moreover, the entrapped Mb realized direct electron transfer with the electrode and displayed an elegant catalytic activity toward the reduction of hydrogen peroxide, nitrite, and trichloroacetic acid, by which the mediator-free biosensors could be fabricated. Atomic force microscopy, UV-Vis spectra, electrochemical impedance spectroscopy, and cyclic voltammetry, etc. were used to characterize the nanoporous ZnO film and Mb-modified ZnO film. Compared to other methods, electrodeposition of porous material supplied a more simple and convenient approach to prepare biocompatible materials for biosensors.     

Acute and Cumulative Effects of Unmodified 50-nm Nano-ZnO on Mice

Nanometer zinc oxide (nano-ZnO) is widely used in diverse industrial and agricultural fields. Due to the extensive contact humans have with these particles, it is crucial to understand the potential effects that nano-ZnO have on human health. Currently, information related to the toxicity and mechanisms of nano-ZnO is limited. The aim of the present study was to investigate acute and cumulative toxic effects of 50-nm unmodified ZnO in mice. This investigation will seek to establish median lethal dose (LD50), a cumulative coefficient, and target organs. The acute and cumulative toxicity was investigated by Karber’s method and via a dose-increasing method, respectively. During the experiment, clinical signs, mortality, body weights, hematology, serum biochemistry, gross pathology, organ weight, and histopathology were examined. The LD50 was 5177-mg/kg·bw; the 95% confidence limits for the LD50 were 5116–5238-mg/kg·bw. It could be concluded that the liver, kidney, lung, and gastrointestinal tract were target organs for the 50-nm nano-ZnO acute oral treatment. The cumulative coefficient (K) was 1.9 which indicated that the cumulative toxicity was apparent. The results also indicated that the liver, kidney, lung, and pancrea were target organs for 50-nm nano-ZnO cumulative oral exposure and might be target organs for subchronic and chronic toxicity of oral administered 50-nm ZnO.     

纳米ZnO对斑马鱼(Danio rerio)肝组织mdr1、nka、ctr1、hif基因mRNA的影响

随着纳米材料的广泛应用,越来越多的人开始关注并研究纳米材料的环境安全性,特别是生物毒性。基因mRNA受环境的影响往往早于毒性损伤,可作为组织损伤的前兆。以斑马鱼为受试生物,运用RT-PCR研究了ZnO纳米颗粒(5.6 mg/L)对肝组织mdr1(多药耐药性基因)、nka(Na+-K+-ATP酶基因)、ctr1(高亲和铜转运蛋白基因)、hif(低氧诱导因子基因)mRNA的影响,这些基因主要与斑马鱼肝组织自身免疫、细胞膜转运功能以及氧化应激有关。实验发现各基因与对照组相比有显著性差异(p<0.05),说明ZnO纳米颗粒对斑马鱼肝组织mdr1、nka、ctr1、hif基因有影响。     

Determination of synergistic effects of antibiotics and Zno NPs against isolated E. Coli and A. Baumannii bacterial strains from clinical samples

The mortality rates has been increased globally due to multidrug resistant (MDR) E.coli and A.baumanii bacterial strains and also there is an emerging resistance of the Enterobacteriaceae family of bacteria to Carbapenem antibiotics (CRE) in Saudi Arabia. The main aim of our research study is to isolate E.coli and A. baumannii bacterial species from various collected clinical samples and to evaluate the MIC and FICI of Colistin, Ciprofloxacin, Meropenem and ZnO NPs and in combination of Colistin, Ciprofloxacin, Meropenem with ZnO NPs.The clinical isolated strains of A. baumannii (MRO-17-13) and A. baumannii (MRO-17–25) was found to be sensitive towards colistin with 0.5 μg/mL concentration, whereas, all the isolated A. baumannii strains showed similar MIC value 2 mg/mL when tested with ZnO NPs, the MIC value for the ZnO NPs was found to be similar for all the E.coli strains 0.25 mg/mL. The effects of all Ciprofloxacin concentrations used in the study were bacteriostatic against E. coli (01UR19006568-01) strain but 1 mg/mL concentration of ZnO NPs alone is showed bactericidal activity, ZnO NPs effect was found to be concentration dependent, as highest concentration of ZnO NPs showed strongest antibacterial effect. In conclusion, more investigation is required to evaluate the acceptable concentration of Zno NPs and antibiotics selected to avoid toxicity and must be tested against more clinically isolated gram-negative bacterial strains.