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101.
102.
Kokkotou E Philippon V Guèye-Ndiaye A Mboup S Wang WK Essex M Kanki P 《Journal of human virology》1998,1(7):469-474
OBJECTIVE: To determine the frequency of the mutant CCR5 delta 32 allele in high-risk HIV-seronegative Africans as compared with the general African population, and to assess its in vitro protective efficacy against HIV-1 infection. STUDY DESIGN: In the homozygous form, the CCR5 delta 32 allele confers resistance to macrophage-tropic (M-tropic) strains of HIV-1. Assuming that genetic characteristics favoring HIV resistance would prevail in a high-risk HIV-seronegative population, we examined the CCR5 genotypes of female commercial sex workers (CSWs) from Dakar, Senegal, who have remained uninfected for an elongated period. METHODS: The CCR5 genetic profile of study participants was determined by polymerase chain reaction (PCR) amplification of genomic DNA followed by sequencing. Peripheral blood mononuclear cells (PBMCs) were infected with different strains of HIV-1 and monitored by p24 enzyme-linked immunosorbent assay (ELISA). RESULTS: We confirmed the presence of two CCR5wt/delta 32 genotypes among 139 individuals (1.44%). PBMCs from these 2 heterozygous individuals were also found to be less susceptible to in vitro infection by an M-tropic HIV-1 primary isolate. CONCLUSIONS: Evidence was found of an increased prevalence of the CCR5wt/delta 32 genotype in a high-risk HIV-seronegative cohort in West Africa. Furthermore, reduced susceptibility to HIV-1 infection among heterozygous individuals supports a role for 32-bp CCR5 deletion in HIV-1 resistance. 相似文献
103.
大鼠肝抑素纯化及其生物活性的检测 总被引:3,自引:1,他引:3
用SephadecG-5凝胶过滤层析法,进一步纯化具肝抑素生物活性的大鼠肝蛋白质粗提品,以分离的大鼠再生肝的肝细胞为靶细胞,体外检测各洗脱峰浓缩物对肝细胞增殖的制率结果证明,E峰浓缩物的抑制作用最强,其活性比为粗提品的20倍,SDS聚丙烯酰胺电泳图及蛋白质迁移率测定表明,该浓缩物的主要成分为分子量13.5kD的多肽。本研究对大鼠肝抑素做了初步纯化,验证了该物质在肝再生中起重要调控作用的生物效应。 相似文献
104.
Neuromodulatory transmitter systems in the cortex and their role in cortical plasticity 总被引:11,自引:0,他引:11
Gu Q 《Neuroscience》2002,111(4):815-835
Cortical neuromodulatory transmitter systems refer to those classical neurotransmitters such as acetylcholine and monoamines, which share a number of common features. For instance, their centers are located in subcortical regions and send long projection axons to innervate the cortex. The same transmitter can either excite or inhibit cortical neurons depending on the composition of postsynaptic transmitter receptor subtypes. The overall functions of these transmitters are believed to serve as chemical bases of arousal, attention and motivation. The anatomy and physiology of neuromodulatory transmitter systems and their innervations in the cerebral cortex have been well characterized. In addition, ample evidence is available indicating that neuromodulatory transmitters also play roles in development and plasticity of the cortex. In this article, the anatomical organization and physiological function of each of the following neuromodulatory transmitters, acetylcholine, noradrenaline, serotonin, dopamine, and histamine, in the cortex will be described. The involvement of these transmitters in cortical plasticity will then be discussed. Available data suggest that neuromodulatory transmitters can modulate the excitability of cortical neurons, enhance the signal-to-noise ratio of cortical responses, and modify the threshold for activity-dependent synaptic modifications. Synaptic transmissions of these neuromodulatory transmitters are mediated via numerous subtype receptors, which are linked to multiple signal transduction mechanisms. Among the neuromodulatory transmitter receptor subtypes, cholinergic M(1), noradrenergic beta(1) and serotonergic 5-HT(2C) receptors appear to be more important than other receptor subtypes for cortical plasticity. In general, the contribution of neuromodulatory transmitter systems to cortical plasticity may be made through a facilitation of NMDA receptor-gated processes. 相似文献
105.
Functional reorganization of primary somatosensory cortex in adult owl monkeys after behaviorally controlled tactile stimulation 总被引:15,自引:0,他引:15
W M Jenkins M M Merzenich M T Ochs T Allard E Guíc-Robles 《Journal of neurophysiology》1990,63(1):82-104
1. Multiple microelectrode maps of the hand representation within and across the borders of cortical area 3b were obtained before, immediately after, or several weeks after a period of behaviorally controlled hand use. Owl monkeys were conditioned in a task that produced cutaneous stimulation of a limited sector of skin on the distal phalanges of one or more fingers. 2. Analysis of microelectrode mapping experiment data revealed that 1) stimulated skin surfaces were represented over expanded cortical areas. 2) Most of the cutaneous receptive fields recorded within these expanded cortical representational zones were unusually small. 3) The internal topography of representation of the stimulated and immediately surrounding skin surfaces differed greatly from that recorded in control experiments. Representational discontinuities emerged in this map region, and "hypercolumn" distances in this map sector were grossly abnormal. 4) Borders between the representations of individual digits and digit segments commonly shifted. 5) The functionally defined rostral border of area 3b shifted farther rostralward, manifesting either an expansion of the cutaneous area 3b fingertip representation into cortical field 3a or an emergence of a cutaneous input zone in the caudal aspect of this normally predominantly deep-receptor representational field. 6) Significant lateralward translocations of the borders between the representations of the hand and face were recorded in all cases. 7) The absolute locations--and in some cases the areas or magnifications--of representations of many skin surfaces not directly involved in the trained behavior also changed significantly. However, the most striking areal, positional, and topographic changes were related to the representations of the behaviorally stimulated skin in every studied monkey. 3. These experiments demonstrate that functional cortical remodeling of the S1 koniocortical field, area 3b, results from behavioral manipulations in normal adult owl monkeys. We hypothesize that these studies manifest operation of the basic adaptive cortical process(es) underlying cortical contributions to perception and learning. 相似文献
106.
目的研制epstein-Bar(EB)病毒诊断试剂。方法将重组痘苗病毒表达的Epstein-Bar病毒(EBV)壳抗原(VCA)主要多肽gp125纯化,作为诊断抗原建立了酶联免疫吸附试验(ELISA),检测了48份鼻咽癌(NPC)病人血清及10份正常人血清中的VCA/IgA抗体。结果该方法与免疫荧光(IF)检测结果一致,但ELISA的平均几何滴度(GMT)是IF的12倍。结论以纯化的EB病毒壳抗原主要多肽gp125作为诊断抗原建立的检测方法,更适合于EBV相关疾病的血清学诊断和血清流行病学调查。 相似文献
107.
用超微结构形态计量方法分析了大鼠30%烫伤后早期肝细胞超微结构的变化规律。烫伤后,肝细胞内精原迅速减少,至6小时,几乎全部消失。烫伤后2小时、6小时。肝细胞内溶酶体的体积密度、数目密度和平均体积均明显增大。线粒体于烫伤后半小时出现基质密度增加、嵴扩张,烫伤后2小时、6小时,线粒体肿胀,其体积密度、平均体积增大。实验结果提示:在严重烧伤后数小时内,肝细胞的超微结构即出现明显的改变。本文对出现这些变化的机制进行了讨论。 相似文献
108.
原位PCR技术检测石蜡包埋脑组织中人巨细胞病毒DNA 总被引:6,自引:0,他引:6
应用原位聚合酶链反应(ISPCR)技术检测了25例尸检畸形胎儿石蜡包埋脑组织中人巨细胞病毒(HCMV)DNA,并与普通PCR及原位杂交(ISH)进行了比较。ISPCR、PCR及ISH检测阳性率分别为44%,36%及20%。与ISH相比较,ISPCR不仅检出阳性率高,而且信号强度增强。研究结果提示,IS-PCR是诊断HCMV感染的快速、敏感、特异的实用方法。 相似文献
109.
N. X. Chin J. W. Gu H. C. Neu 《European journal of clinical microbiology & infectious diseases》1990,9(9):685-691
The activity of the new oral cephalosporin Bay v 3522 was compared to that of six other beta-lactam agents. Bay v 3522 inhibited methicillin-susceptibleStaphylococcus aureus andStaphylococcus epidermidis at 2 µg/ml, compared to MICs of 8 µg/ml for the other cephalosporins tested. It was more active againstStreptococcus pyogenes (MIC 0.06 µg/ml) than cefuroxime, cefixime, cephalexin and cefaclor. Groups B, C and G streptococci were inhibited at 0.12 µg/ml, while the MIC90 forStreptococcus bovis and viridans streptococci was 0.5 and 2 µg/ml, respectively. The MIC90 for enterococci andListeria monocytogenes was 8 µg/ml.Clostridium perfringens was inhibited by 0.12 µg/ml, but mostBacteroides spp. were resistant. The MIC90 for beta-lactamase positiveEscherichia coli (producing primarily TEM-1) was >64 µg/ml and for beta-lactamase negative strains 16 µg/ml. The MIC90 for high-level beta-lactamase producingKlebsiella pneumoniae was >64 µg/ml versus 4 µg/ml for other isolates. The MIC90 forMoraxella catarrhalis was 2 µg/ml, forHaemophilus influenzae 1 µg/ml, and forNeisseria gonorrhoeae 4 µg/ml.Enterobacter cloacae, Citrobacter freundii, Proteus mirabilis, Providencia spp. andPseudomonas aeruginosa were resistant. Bay v 3522 was destroyed by TEM-1, SHV-1, TEM-3 and P99 beta-lactamases. 相似文献
110.