钛合金和钴铬合金表面白色念珠菌粘附的研究

目的比较钛合金(Ti-6Al-4V)和钴铬合金(Chromium-Cobaltalloy)表面白色念珠菌粘附能力的大小,研究表面粗糙度与细菌粘附的关系。方法将不同表面粗糙度的钛合金和钴铬合金试件进行白色念珠菌体外粘附试验,采用菌落形成计数法测定试件表面的细菌粘附量。结果各钛合金试件组的细菌粘附量均少于相同表面粗糙度的钴铬合金试件组,两种金属试件表面的细菌粘附量均随表面粗糙度的增大而增加。结论钛合金较钴铬合金更能减少由白色念珠菌引起的义齿性口炎等并发症,同时修复体表面严格的研磨抛光也能有效减少这些并发症。     

抗生素对细菌粘附的影响

抗生素能改变细菌表面性状;电镜观察显示,抗生素存在时细菌的某些超微结构会出现一些变化。某些抗生素能干扰细菌表面结构组分的代谢及功能,另一些抗生素则能破坏细菌表面结构。不论抗生素以何种机制发挥作用,由于细菌表面生化特征的变化,细菌与宿主细胞间     

微波加热时基托树脂收缩量的研究

目的,针对基托树脂固化的特性,探讨微波加热对树脂收缩量的影响。方法:采用四种常用基托树脂,分别采取单纯微波固化和微波加压固化聚合后,测定开盒后一周内树脂的聚合收缩情况。结果:两种固化方法收缩量均较小,适应性强。微波加压固化虽收缩量相对稍大但收缩均匀各树脂间无显著差异。结论:微波加热固化清洁高效,基托树脂结构致密,收缩量小,是今后树脂固化的一个发展方向。     

细菌粘附素的分子结构和装配机制

细菌感染的第一步是必须粘附于易感细胞,以获得立足点,在局部繁殖,释放毒素和酶类损坏组织,导致感染,细菌的粘附作用主要靠粘附素特异的识别结合到宿主细胞的受体,使细胞在局部定居,本文主要综述菌毛粘附素的分子结构及其因控制,菌毛粘附素如何通过四种典型途径装配,以及参与装配的蛋白质是如何协调功能的研究进展。     

细菌粘附宿主细胞外基质的分子基础

本文对细菌粘附宿主组织时与胞外基质（ＥＣＭ）结合的粘附素分子进行了综述。重点介绍了这类识别粘连基质分子的微生物表面成分的性质、结构和功能。具体涉及的金黄色葡萄球菌、化脓性链球菌、大肠杆菌、肺炎克雷伯菌、耶尔森菌和气单胞菌等,涉及的ＥＣＭ分子有纤维结合蛋白（Ｆｎ）、胶原及血纤维蛋白原。此外,还对ＭＳＣＲＡＭＭ－ＥＣＭ相互作用在细菌定居后,组织向性及致病中的作用进行了讨论。     

两种生物状态肠道益生菌的粘附和粘附拮抗效应的对比研究

目的:研究活菌和灭活菌两种生物状态的肠道主要益生菌--德氏乳杆菌、双歧杆菌和肠球菌对肠黏膜上皮细胞粘附性及其对肠道几种常见病原菌的粘附拮抗效应.方法:用光镜和电镜技术分析了两种生物状态的三种益生菌对肠黏膜上皮细胞的粘附指数,通过排除实验、竞争实验和替代实验研究了两种生物状态益生菌对侵袭性大肠埃希菌、产毒性大肠埃希菌和痢疾志贺菌的粘附拮抗效应,应用平板扩散法观察了三种益生菌的代谢乏液对上述肠道病原菌的抑制能力.结果:德氏乳杆菌和肠球菌的灭活状态较活菌状态对肠黏膜上皮细胞的粘附性显著增高,双歧杆菌经灭活后对细胞的粘附性与活菌相比差异无显著性,两种生物状态的三种益生菌对肠道致病菌均具有粘附拮抗作用.滤过后的德氏乳杆菌、双歧杆菌和肠球菌的代谢乏液对侵袭性大肠埃希菌、产毒性大肠埃希菌和痢疾志贺菌均具有较明显的抑制作用,经42℃、65℃和100℃加热不影响德氏乳杆菌和双歧杆菌代谢乏液的抑菌作用.结论:灭活状态的德氏乳杆菌、双歧杆菌和肠球菌是具有潜在开发价值的微生态制剂.     

细菌在油水界面粘附的理论、特性及应用

细菌在油水界面粘附主要应用于烷烃污染的环境修复、石油开采与加工、食品加工等方面,其研究已经引起各界的广泛关注。本文基于XDLVO理论阐述细菌在油水界面的粘附机理;总结细菌表面特性、油相及水相性质对细菌粘附的影响;介绍细菌粘附作用在微生物驱油、生物乳化与破乳以及烷烃降解方面的应用,并对今后的研究方向提出展望。     

两种树脂固相合成机体保护肽的比较

目的:比较Wang树脂和二氯三苯甲基树脂(以下简称二氯树脂)在固相合成机体保护肽中的表现,为工业化生产提供理论依据。方法:通用的Fmoc固相合成法制备机体保护肽,通过比色法对两种树脂与氨基酸的偶联率进行比较,用质谱(MALDI-TOFMS)对粗肽进行鉴定分析,用反相高效液相色谱(RP-HPLC)进行粗肽的分析和纯化。结果:显示以二氯树脂作载体,第一个氨基酸的连接率,以及机体保护肽的纯度和产率都要明显高于Wang树脂。结论:二氯树脂作载体合成机体保护肽更适合大规模工业化生产的要求。     

细菌在阴离子交换树脂上的吸附研究

报道了细菌 (E .coliK12和S .aureus)在阴离子交换树脂 (SuperQ和DEAE)上的静态吸附行为。采用静态法测定 30℃以及 37℃下E .coliK12和S .aureus在SuperQ和DEAE上的吸附等温线 ,分别用Freundlich和Langmuir方程拟合。实验表明 ,用Fre undlich方程拟合 ,得到较为满意的结果 ,其相关系数最大为 0 .995 ,最小为 0 .991;Freundlich等温线指数 1/n =0 .3～ 0 .4 ;而且在30℃下比在 37℃下更有利于吸附。同样采用静态法测定了吸附量随pH值的变化趋势。结果表明 ,对E .coliK12和S .aureus在SuperQ上的吸附 ,pH >6 .0～ 7.0的吸附量较pH2 .0～ 5 .0之间的多。     

液体培养条件下细菌浓度两种测定方法比较

液体培养细菌后,分别测定培养液、培养液沉淀 无菌盐水的吸光度,结果存在明显差异。采用稀释平板法和显微计数法测定了培养液中细菌数量,并推导出嗜水气单胞菌活菌数与吸光度的关系为logI0/I=6.848×10-25·C。     

Extremely-Low Frequency Magnetic Field Effects on Sulfate Reducing Bacteria Viability

50?Hz magnetic fields effects on Sulfate Reducing Bacteria (SRB) viability were studied by colony forming units (CFU) counting. We found a 15% decrease of CFU number after magnetic field exposure (B=7.1?mT, f=50?Hz, t=24?min) compared to the control samples. These results are in good agreement with our previous work on other bacterial strains. The magnetic field effects on SRB are relatively large for small magnetic fields. The data correlations have been subjected to a simple physical chemical analysis, yielding surprisingly large estimates for the characteristic magnetic reaction susceptibility, even when the entire bacterium is assumed to be the direct target of interaction of the magnetic ac fields for the exposures in the time range from 3–24?min.     

小麦内生细菌及其对根茎部主要病原真菌的抑制作用

对小麦植株不同生育期、不同器官的内生细菌进行了分离和数量变化分析.结果表明,根、茎、叶及未成熟籽粒等器官中存在大量的内生细菌,鲜组织中平均约含内生细菌5.0×10⁵ CFU·g^-1,其中根系中内生细菌数量达7.8×10⁵ CFU·g^-1,而茎秆、叶片和未成熟籽粒中内生细菌数量分别为4.8×10⁵、3.2×10⁵和2.8×10⁵ CFU·g^-1.内生细菌数量在不同生育期也存在差异,幼苗期平均约为3.1×10⁵ CFU·g^-1、拔节期和灌浆期分别为5.7×10⁵和7.0×10⁵ CFU·g^-1.不同小麦田块之间存在明显差异,长武县一田块植物鲜组织中内生细菌的数量为6.1×10⁵ CFU·g^-1,而大荔县一田块约为3.9×10⁵ CFU·g^-1.试验结果发现,对小麦全蚀病菌具有拮抗作用的内生细菌有51株、对小麦纹枯病菌具有抑制作用的内生细菌有45株.用平板对峙法测定,有71株对两种病原真菌均有拮抗作用,对小麦全蚀病菌抑菌圈直径大于10 mm的有23株,其中来源于根系、茎秆、叶片和籽粒的分别为6株、7株、9株和1株;对小麦纹枯病菌抑菌圈超过10 mm的有20株,其中来源于根系、茎秆、叶片和籽粒的分别为7株、5株、7株和1株,说明从小麦叶片诱捕分离的内生细菌中,对小麦全蚀病菌和纹枯病菌抑菌作用较强的分离株比率最高,其次为茎秆,而根部和未成熟籽粒中比例明显较低.     

Adhesion of Pseudomonas aeruginosa,Achromobacter xylosoxidans,Delftia acidovorans,Stenotrophomonas maltophilia to contact lenses under the influence of an artificial tear solution

Abstract

Corneal infection is a devastating sight-threatening complication that is associated with contact lens (CL) wear, commonly caused by Pseudomonas aeruginosa. Lately, Achromobacter xylosoxidans, Delftia acidovorans, and Stenotrophomonas maltophilia have been associated with corneal infection. This study investigated the adhesion of these emerging pathogens to CLs, under the influence of an artificial tear solution (ATS) containing a variety of components commonly found in human tears. Two different CL materials, etafilcon A and senofilcon A, either soaked in an ATS or phosphate buffered saline, were exposed to the bacteria. Bacterial adhesion was investigated using a radio-labeling technique (total counts) and plate count method (viable counts). The findings from this study revealed that in addition to P. aeruginosa, among the emerging pathogens evaluated, A. xylosoxidans showed an increased propensity for adherence to both CL materials and S. maltophilia showed lower viability. ATS influenced the viable counts more than the total counts on CLs.     

The Influence of Biosurfactants Released by S. mitis BMS on the Adhesion of Pioneer Strains and Cariogenic Bacteria

The influence of Streptococcus mitis BMS biosurfactants on the adhesion of eight pioneer and four cariogenic oral bacterial strains was, for a first screening, examined in a microtiter plate assay. The adhesion to pellicle-coated wells of three cariogenic strains was inhibited > 70% by the biosurfactants, while only one pioneer strain showed > 70% reduction. The reduction for the other strains did not exceed 50%. Subsequently, adhesion of Streptococcus mutans ATCC 25175 and Streptococcus sobrinus HG 1025, both cariogenic strains, and Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, two pioneer strains, to biosurfactants-coated enamel with and without a salivary pellicle was studied in a parallel plate flow chamber. A biosurfactants coating to enamel with or without a pellicle caused a reduction in the number of adhering cariogenic organisms, although no such reduction was observed for the pioneer strains. Consequently, it is concluded that S. mitis BMS biosurfactants may play a protective role against adhesion of cariogenic bacteria.     

The isolation and characterization of putative mesenchymal stem cells from the spiny mouse

The bone marrow represents the most common source from which to isolate mesenchymal stem cells (MSCs). MSCs are capable of differentiating into tissues of the three primary lineages and have the potential to enhance repair in damaged organs through the principals of regenerative medicine. Given the ease with which MSCs may be isolated from different species the aim of this study was to isolate and characterize putative bone marrow derived MSCs from the spiny mouse, Acomys cahirinus. MSCs were isolated from the spiny mouse in a traditional manner, and based on plastic adherence, morphology, colony forming unit-fibroblast assays and functional assessment (adipogenic, osteogenic and chondrogenic differentiation potential) a population of putative mesenchymal stem cells from the compact bone of the spiny mouse have been isolated and characterized. Such methodological approaches overcome the lack of species-specific antibodies for the spiny mouse and could be employed for other species where the cost of generating species-specific antibodies is not warranted.     

细菌对肉鸡肠粘液的粘附作用

研究两歧双歧杆菌、嗜酸乳杆菌、禽大肠杆菌O78、大肠杆菌 ATCC 25922、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肉鸡不同部位肠粘液糖蛋白的粘附性能,探讨两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的抗粘附作用。结果表明：在不同的肠道部位,两歧双歧杆菌、嗜酸乳杆菌、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肠粘液糖蛋白均有不同的粘附作用,而禽大肠杆菌O78、大肠杆菌 ATCC 25922在各肠段粘液上的粘附性能则相近;在相同的肠道部位,所试益生菌的粘附能力大于病原菌;两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的粘附有不同的阻断作用,同时二者有时还存在互补抗粘附作用。     

山葵杀菌作用的研究

报道了山葵提取物对细菌的致死作用 ,特别是山葵对病原菌有明显的杀灭作用。在山葵提取物浓度为 0.5 %～ 0.8%,作用时间为 90～ 1 2 0min的条件下 ,对几种病原菌的杀菌率为 80 %～ 97%。这对杀灭有害病原菌找到了一条新途径 ,对防止病原菌的传播搞好环境卫生、保证人类健康有积极意义。     

水生细菌生物量的估算方法*

细菌的生物量是海洋微生物研究的关键参数之一。目前,细菌生物量估算方法主要根据其体积的大小进行换算,但换算的方式也不尽一致。对细菌体积和细菌碳含量主要的测定方法、体积与生物量之间换算系数、换算模式进行介绍,评述。认为流式细胞术是测定细菌体积较为合适的方法,X-射线微量分析法是测定单个细菌生物量(碳含量)最合适的方法,异速生长模式是目前生物量换算过程较为常用的模式。