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41.
Infectivity of preserved Cryptosporidium parvum oocysts for immunosuppressed adult mice 总被引:1,自引:0,他引:1
Shiguang Yang Mark C. Healey Chunwei Du 《FEMS immunology and medical microbiology》1996,13(2):141-145
Abstract The present study was undertaken to determine the infectivity of Cryptosporidium parvum oocysts for immunosup-pressed adult C57BL/6N mice after the oocysts had been stored from 1–48 months at 4°C in 2.5% potassium dichromate. All mice inoculated with oocysts 1–18 months old developed patent infections, while mice inoculated with older oocysts remained uninfected. The prepatent period was extended from 2 to 6 or 7 days as the storage time for oocysts increased. The finding that C. parvum oocysts remain infective for mice for at least 18 months offers important economic and time-saving advantages for investigators who frequently require large numbers of oocysts that must be painstakingly purified from calf manure. 相似文献
42.
本实验采用D-氨基半乳糖(D-GalN)诱导的大鼠急性肝损伤模型,观察大鼠肝脏组织化学的变化,探讨肝炎平对急性肝损伤的保护作用。实验分为四组,即正常对照组、模型组、肝炎平及肝得健保护组。结果表明:肝炎平对肝细胞膜系统有一定的保护作用。肝炎平组和肝得健组SDH、CCO及ChE活性明显高于模型组,且与正常对照组相近。本实验模型组ACP的活性明显高于正常组,而肝炎平组ACP的活性明显低于模型组,与正常对照组无显著性差异。提示:肝炎平可显著改善因D-氨基半乳糖所致肝损害的作用。且其对肝细胞的保护作用与肝得健一致。 相似文献
43.
中药固真方对一些与细胞增殖有关基因表达的影响姚明忠,顾文聪,丁卫,韩志芬,杜国光(上海中医药大学生物化学教研室,上海200032)(北京医科大学生物化学与分子生物学系,北京100083)中药固真方(VRF)具有补肾益精、延缓衰老的作用[1].能提高成... 相似文献
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A role for natural simian immunodeficiency virus and human immunodeficiency virus type 1 nef alleles in lymphocyte activation. 总被引:7,自引:2,他引:5 下载免费PDF全文
A T-lymphoid cell line termed 221 was derived from a rhesus monkey infected with herpesvirus saimiri. Growth of 221 cells was dependent on the addition of interleukin-2 (IL-2) to the culture medium. In the absence of IL-2, 221 cells arrested in G0-G1 but did not die. Simian immunodeficiency virus (SIV) replicated efficiently in IL-2-stimulated 221 cells whether or not the nef gene was present. In the absence of IL-2, nef-containing SIV replicated 8 to 100 times more efficiently in 221 cells than did the same virus lacking nef. nef-containing virus preferentially stimulated the production of IL-2 from 221 cells. HIV-1 nef and v-ras genes, but not the c-ras gene, were shown to substitute functionally for SIV nef when tested as recombinant viruses in this assay system. These results demonstrate a role for natural nef in causing lymphoid cell activation, and they provide a system for delineating the biochemical mechanisms responsible for this activation. 相似文献
46.
Two distinct CCR5 domains can mediate coreceptor usage by human immunodeficiency virus type 1. 总被引:11,自引:5,他引:6 下载免费PDF全文
B J Doranz Z H Lu J Rucker T Y Zhang M Sharron Y H Cen Z X Wang H H Guo J G Du M A Accavitti R W Doms S C Peiper 《Journal of virology》1997,71(9):6305-6314
The chemokine receptor CCR5 is the major fusion coreceptor for macrophage-tropic strains of human immunodeficiency virus type 1 (HIV-1). To define the structures of CCR5 that can support envelope (Env)-mediated membrane fusion, we analyzed the activity of homologs, chimeras, and mutants of human CCR5 in a sensitive gene reporter cell-cell fusion assay. Simian, but not murine, homologs of CCR5 were fully active as HIV-1 fusion coreceptors. Chimeras between CCR5 and divergent chemokine receptors demonstrated the existence of two distinct regions of CCR5 that could be utilized for Env-mediated fusion, the amino-terminal domain and the extracellular loops. Dual-tropic Env proteins were particularly sensitive to alterations in the CCR5 amino-terminal domain, suggesting that this domain may play a pivotal role in the evolution of coreceptor usage in vivo. We identified individual residues in both functional regions, Asp-11, Lys-197, and Asp-276, that contribute to coreceptor function. Deletion of a highly conserved cytoplasmic motif rendered CCR5 incapable of signaling but did not abrogate its ability to function as a coreceptor, implying the independence of fusion and G-protein-mediated chemokine receptor signaling. Finally, we developed a novel monoclonal antibody to CCR5 to assist in future studies of CCR5 expression. 相似文献
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48.
畜禽遗传资源冷冻保存中的取样方法探讨 总被引:1,自引:0,他引:1
本文基于遗传学和数理统计原理,提出了运用冷冻生殖细胞的方法长期保存畜禽遗传资源时,冷冻生殖细胞的4种取样方法,并推证了其误差公式和最低保存数量的估计公式。最后通过实例对公式的实际应用作了说明和讨论分析。 相似文献
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50.
我国汉族人群的乙二醛酶Ⅰ遗传多态性 总被引:1,自引:0,他引:1
用琼脂糖平板凝胶电泳技术分析了我国六个城市的汉族共1238人的红细胞乙二醛酶I的遗传多态性。每个汉族人群的受检人数和GLO1*1基因频率分别为:郑州200人(0.1023),哈尔滨195人(0.1103),呼和浩特210人(0.1259),贵阳204人(0.1373),兰州210人(0.1476),西安199人(0.1508)。中国不同地区汉族人群之间的GLOI基因频率分布存在显著性差异,但这种差异明显小于中国不同少数民族之间的差异。 相似文献