SCID小鼠肠道菌群失调对深部白色念珠菌感染的影响研究

目的建立重度联合免疫缺陷（SCID）小鼠白色念珠菌感染模型,探讨肠道菌群失调与深部白色念珠菌感染的联系。方法SCID小鼠随机口服万古霉素水溶液7d,饥饿24h后给予白色念珠菌灌胃,建立小鼠白色念珠菌感染模型,观察小鼠死亡情况。荧光定量PCR检测肠道细菌总量、基质辅助激光解析电离飞行时间质谱仪鉴定肠道菌群种类,并应用扫描电镜观察肠壁黏膜组织超微结构的改变。结果应用万古霉素可致肠道菌群失调,肠道黏膜完整性受损。在万古霉素致肠道菌群失调的基础上,外源性白色念珠菌攻击可加重肠道菌群失调和肠壁黏膜损伤程度,促进深部白色念珠菌感染的发生。结论肠道菌群失衡可以导致深部白色念珠菌感染的发生,肠壁黏膜的完整性可能参与了肠道白色念珠菌播散过程。     

Assessment of arbovirus vector infection rates using variable size pooling

Pool testing of vector samples for arboviruses is widely used in surveillance programmes. The proportion of infected mosquitoes (Diptera: Culicidae) is often estimated from the minimum infection rate (MIR), based on the assumption of only one infected mosquito per positive pool. This assumption becomes problematic when pool size is large and/or infection rate is high. By relaxing this constraint, maximum likelihood estimation (MLE) is more useful for a wide range of infection levels that may be encountered in the field. We demonstrate the difference between these two estimation approaches using West Nile virus (WNV) surveillance data from vectors collected by gravid traps in Chicago during 2002. MLE of infection rates of Culex mosquitoes was as high as 60 per 1000 at the peak of transmission in August, whereas MIR was less than 30 per 1000. More importantly, we demonstrate roles of various pooling strategies for better estimation of infection rates based on simulation studies with hypothetical mosquito samples of 18 pools. Variable size pooling (with a serial pool sizes of 5, 10, 20, 30, 40 and 50 individuals) performed consistently better than a constant size pooling of 50 individuals. We conclude that variable pool size coupled with MLE is critical for accurate estimates of mosquito infection rates in WNV epidemic seasons.     

不同加热方式对嗜肺军团菌环介导等温扩增检测法的影响

目的:研究不同的加热方式对嗜肺军团菌环介导等温扩增检测法的影响方法:用已知的13株嗜肺军团菌样本,采用空气浴、水浴和PCR仪同时进行环介导等温扩增,观察沉淀反应、荧光反应以及产物电泳结果。结果:水浴和PCR仪加热LAMP反应的沉淀产物较多,荧光反应较强,电泳检测结果较为明显。空气浴的3种检测结果均较弱。结论:采用水浴和PCR仪进行环介导等温扩增反应的效果较好,从仪器设备的成本及实验条件考虑,采用水浴是环介导等温扩增反应首选的加热方式。     

外科深部真菌感染的病原学分析

目的分析外科住院患者合并真菌感染状况。方法分离的真菌用API 20C AUX真菌鉴定条,用ATB FUNGUS-2进行药敏试验。结果真菌的种类分布中第1位是白色念珠菌占53%,第2位是热带念珠菌占20%,第3位是光滑念珠菌占14%,第4位是近平滑念珠菌占4%,第5位是其余念珠菌占2%;真菌在外科各区分布中,外科ICU占42%,移植外科占25%;真菌在各类标本分布中,痰占43%,尿液占13%,粪便占10%,引流液占9%,血液占7%;真菌对药物5-氟胞嘧啶、两性霉素B、氟康唑、伊曲康唑的药物敏感性分别是93%、98.9%、90.8%、59.8%。结论外科真菌感染集中在重症病区(ICU),分离的致病真菌主要是白色念珠菌、热带念珠菌、光滑念珠菌,真菌对两性霉素B敏感性最高。     

Preparation and partial characterization of a Lactobacillus lactis bacteriophage

High-titer lysates of a bacteriophage active against Lactobacillus lactis were prepared from liquid cultures as well as from areas of confluent lysis in soft-agar overlayers. Phage concentration and purification were accomplished by means of polyethylene glycol precipitation, differential centrifugation, and cesium chloride gradient centrifugation. The buoyant density of this phagein cesium chloride was 1.4795 g/ml. Characterization of phage growth cycle by one-step growth experiments under optimal conditions showed that the latent period was about 120 min, that the rise period lasted approx. 130 min, and that the average burst-size was about 80.Abbreviations p.f.u. plaque forming units - m.o.i. multiplicity of infection - PEG polyethylene glycol - SSC standard saline citrate solution     

用共聚焦激光扫描显微镜观测GFP标记的内生固氮菌Klebsiella oxytoca SA2侵染水稻根

用高效绿色荧光蛋白（green fluorescent protein,GFP）突变体EGFPmut2的基因标记内生固氮菌－－产酸克雷伯氏菌（Klebsiella axytoca (Fluegge)Lautrop）SA2,用标记菌接种限菌培养条件下生长的水稻（Oryza sativa L.）幼苗,在接种后1、2、4 、8、12、16和21d,用共聚焦激光扫描显微镜对水稻鲜根进行光学切片,显示了标记菌从水稻根成熟区表面向根内入侵的过程。定殖在根表面的标记菌主要从侧根伸出的位置侵入侧根皮层,从邻近发生侧根的位置进入内皮层和维管柱。SA2还能从初生根成熟区无侧根伸出的位置侵入皮层向维管柱迁移。SA2入侵水稻根引发了水稻根局部的过敏反应以阻滞细菌地下海主侵,表现为侵入根内的细菌周围的根细胞细胞壁变厚,在蓝光下发出很强的黄绿荧光。     

Construction of a fusion protein carrying antigenic determinants of enteric clostridial toxins

Clostridium difficile and Clostridium perfringens type A are infectious agents of enteric diseases. The main virulence factors of these microorganisms include toxins A and B of C. difficile (ToxA and ToxB) and enterotoxin of C. perfringens (Cpe). In this study genetic constructions have been created for the expression of ToxA, ToxB and Cpe fragments either as individual components or as a hybrid multidomain (ToxA-ToxB-Cpe) protein. Rabbit monospecific sera raised against individual peptides reacted with the chimeric product indicating that the corresponding antigenic determinants were correctly expressed on the hybrid molecule. Furthermore, mice immunized with the fusion protein produced antibodies specific to each of the three separate components. These data suggest that the constructed three-domain molecule could be used in future studies for development of a vaccine against enteric clostridial diseases.     

不同方法建立多重耐药铜绿假单胞菌肠道感染动物模型的比较和评价

目的探讨建立肠道多重耐药细菌感染动物模型的方法,为实验研究和治疗因耐药菌引起的感染提供良好的模型。方法 24只6周龄SPF级雄性BALB/c小鼠分成4组:正常对照组、MDR-PA组、MDR-PA+抗生素组和MDR-PA+禁食组,6只/组。分别给予生理盐水灌胃、PA悬液灌胃、自由饮用含头孢曲松钠水后PA悬液灌胃和禁食后PA悬液灌胃。实验结束后对结肠组织进行病理学观察和炎症评分;检测炎症因子TNF-α和INF-γ浓度。结果结肠组织病理表现出不同程度的炎症变化;炎症因子TNF-α和INF-γ浓度较对照组均明显增加,有显著统计学意义。结论三种方法均可成功建立肠道多重耐药铜绿假单孢菌感染的动物模型,可根据不同实验目的选择不同的建立模型方法。     

具免疫时滞的HIV感染模型动力学性质分析

讨论了一类具免疫时滞的HIV感染模型.分析了未感染平衡点的全局渐近稳定性,给出了感染无免疫平衡点及感染免疫平衡点局部渐近稳定的充分条件.数值模拟结果表明,当易感细胞生成率的取值使得基本再生数满足平衡存在的条件且低于某一临界值时,时滞对平衡点的稳定性没有影响;若大于该临界值,随着时滞增大,稳定性开关发生,平衡点不稳定,出现一系列Hopf分支,最终表现为周期波动模式.     

HIV-1膜抗原部分位点的改造对假病毒形成及感染能力的影响

研究HIV-1膜抗原部分位点的改造对假病毒形成及病毒感染能力的影响。本实验采用环形诱变和DpnΙ筛选的方法对env进行定点突变。用获得的克隆和骨架质粒pSG3△env共转染293FT细胞,收获假病毒后用TZM-bl细胞进行单周期感染试验,检测特定位点改造对功能性假病毒形成能力的影响。改造之前样品S12-42-1的免疫印记的实验结果显示弥散的条带,蛋白大小约160kD,但单周期感染试验中其S/CO(样品信号值与临界值的比值)小于1,即不能形成假病毒。将该样品第457位氨基酸由丙氨酸变成天冬氨酸后,用突变体S12-42M进行单周感染试验,其S/CO值为6.65,表示突变体能够形成假病毒。结果表明HIV-1膜抗原部分位点的改变影响假病毒的形成或假病毒感染细胞的能力。