Cholera toxin B-subunit incorporation into synaptic vesicles of the neuromuscular junction of the rat

Summary The B-subunit of cholera toxin, a nontoxic macromolecule which binds specifically to GM1 ganglioside, was conjugated to colloidal gold and injected into skeletal muscle of the rat. It was taken up rapidly in vesicles in the terminal axons at the neuromuscular junctions. Injection of albumin-colloidal gold conjugates resulted in an insignificant uptake. The results indicate that uptake of extracellular macromolecules into the terminal axon of the neuromuscular junction may be greatly enhanced by binding to gangliosides at the presynaptic membrane, and that it may occur without association with vesicular recycling related to transmitter release.The study was supported by grants from the Swedish Medical Research Council (proj. No. 07122).—Part of this study was performed at INSERM U-153, Paris, headed by Dr M. Fardeau.     

Cholera toxin structure, gene regulation and pathophysiological and immunological aspects

Many notions regarding the function, structure and regulation of cholera toxin expression have remained essentially unaltered in the last 15 years. At the same time, recent findings have generated additional perspectives. For example, the cholera toxin genes are now known to be carried by a non-lytic bacteriophage, a previously unsuspected condition. Understanding of how the expression of cholera toxin genes is controlled by the bacterium at the molecular level has advanced significantly and relationships with cell-density-associated (quorum-sensing) responses have recently been discovered. Regarding the cell intoxication process, the mode of entry and intracellular transport of cholera toxin are becoming clearer. In the immunological field, the strong oral immunogenicity of the non-toxic B subunit of cholera toxin (CTB) has been exploited in the development of a now widely licensed oral cholera vaccine. Additionally, CTB has been shown to induce tolerance against co-administered (linked) foreign antigens in some autoimmune and allergic diseases. Received 25 October 2007; accepted 12 December 2007     

不同血清型禽霍乱巴氏杆菌免疫的研究Ⅱ.免疫制剂的制备与检验

在试验研究基础上 ,应用发育鸡胚培养的禽多杀性巴氏杆菌 ,制备相应的灭活免疫原 ,加入油乳剂免疫增强剂 ,制备了相应的免疫制剂。通过对鸡做免疫接种后的感染保护试验 ,初步表明具有较好的免疫保护效果 ,从而为控制禽霍乱的发生与流行 ,提供了一种新型的免疫预防制剂     

G蛋白在杨树气孔运动中的作用

群众杨叶片下表皮经过不同浓度的G蛋白激活剂霍乱毒素(CTX)处理后,在扫描电镜下观察了气孔开度的变化,并用透射电镜结合X-射线能谱显微分析技术,对保卫细胞内的K^ 、Cl^-含量进行了研究。结果表明：CTX能促进气孔关闭,作用强度随CTX浓度的增加而增强。伴随着气孔关闭,保卫细胞液泡和细胞质中的K^ 、Cl^-含量都明显下降,而细胞壁中的K^ 、Cl^-含量增加。这提示G蛋白可能通过对保卫细胞内K^ 、Cl^-的调节作用而参与了气孔运动过程。     

Use of aggregating cell cultures for toxicological studies

Summary Relatively simple techniques are now available which allow the preparation of large quantities of highly reproducible aggregate cultures from fetal rat brain or liver cells, and to grow them in a chemically defined medium. Since these cultures exhibit extensive histotypic cellular reorganization and maturation, they offer unique possibilities for developmental studies. Therefore, the purpose of the present study was to investigate the usefulness of these cultures in developmental toxicology. Aggregating brain cell cultures were exposed at different developmental stages to model drugs (i.e., antimitotic, neurotoxic, and teratogenic agents) and assayed for their responsiveness by measuring a set of biochemical parameters (i.e., total protein and DNA content, cell type-specific enzyme activities) which permit a monitoring of cellular growth and maturation. It was found that each test compound elicited a distinct, dose-dependent response pattern, which may ultimately serve to screen and classify toxic drugs by using mechanistic criteria. In addition, it could be shown that aggregating liver cell cultures are capable of toxic drug activation, and that they can be used in co-culture with brain cell aggregates, providing a potential model for complementary toxicological and metabolic studies.     

禽霍乱琼扩抗原和抗血清的制备

将禽多杀性巴氏杆菌 1,3和 4型菌株 ,分别接种于加有绵羊血红素的马丁氏肉汤中进行培养 ,将培养物混合后离心 ,并漂洗沉淀物 ,制成琼扩抗原 ,与NDV ,HAAV ,APIV ,IC ,SP ,MG ,MS和IBDV等抗血清无交叉反应。将 3个血清型细菌培养物等量混合后 ,免疫 6周龄SPF鸡制备禽霍乱抗血清     

新兽药复方畜禽乐防治禽霍乱效果的研究

目前禽霍乱仍是危害我国家禽的主要疾病之一，虽然有效药物很多，由于反复使用，疗效逐渐下降，研制出一药多用、疗效高、无副作用、体内无抗药性的药物是当前的主要任务．１９９１～１９９４年我们承担了吉林省科委“新兽药方８１２－２型制剂（畜禽乐）的研制与应用”，课题通过研制和试验证明该药对人工感染禽霍乱治愈率９３．３％、保护率为１００％，对自然感染禽霍乱治愈率为１００％．     

具有环境传播和生理年龄结构的霍乱模型研究

基于霍乱在人群和环境之间的传播规律, 以及生物体间个体的差异性, 提出一类具有环境传播和生理年龄结构的霍乱模型, 并利用半群理论证明了模型全局正解的存在唯一性. 进一步, 通过线性近似方法推导出基本再生数R₀的表达式并得出结论: 当R₀<1时, 无病平衡态是全局渐近稳定的; 当R₀>1时, 无病平衡态是不稳定的, 模型存在唯一的地方病平衡态且在一定条件下是局部渐近稳定的. 通过数值模拟解释了主要的理论结果.     

乌骨鸡禽霍乱的病原分离鉴定和药敏试验

应用常规分离鉴定技术,对西宁市某特种珍禽养殖场92日龄濒死和病死乌骨鸡进行禽霍乱病原分离,并与多杀性巴氏杆菌质控菌株进行生化特性比较。结果显示:分离株与质控菌株间有一定的生化差异,但符合禽型巴氏杆菌的生化特性;同时对分离菌株进行了药物筛选,选取中介和敏感药物进行交替治疗,取得了一定的治疗效果。     

民国时期四川省霍乱流行的时空规律及驱动因素

基于疫灾史料和环境资料,采用时空分析方法、地理加权回归及地理探测器,分析民国时期四川省霍乱的时空分布规律及驱动因素.研究发现：1) 民国时期四川省的霍乱疫情在波动中发展,出现1916年、1920年、1939年、1945年四个明显高峰,高发于夏秋两季.2) 霍乱疫情波及范围呈现扩大趋势,由早期的斑块分散状到中后期逐渐集中连片扩展,四川中部是霍乱爆发的集聚区.3) 自然和人文环境因素交织推动霍乱的出现和发展,影响因素的交互作用皆呈非线性增强和双因子增强,人口数量、洪涝灾害因素具有正向影响且存在明显的空间差异.研究可为烈性传染病的防控提供历史经验.