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目的观察异丙酚对失血性休克大鼠小肠黏膜屏障功能的影响。方法 36只雄性SD大鼠随机分为对照组和异丙酚组,制作失血性休克模型,经股静脉回输等量林格氏液,异丙酚组加用异丙酚5 mg/kg。18 h后处死大鼠,鲎试＋验测定血浆内毒素含量,免疫组化法检测小肠黏膜固有层IgA细胞,TUNEL法检测小肠黏膜细胞凋亡。结果与对照组＋比较,异丙酚组血浆内毒素含量明显减少,小肠黏膜上皮细胞凋亡指数明显降低,而小肠黏膜固有层IgA细胞数显著升高,差异均有统计学意义（P〈0.01）。结论异丙酚可保护失血性休克对大鼠小肠道黏膜屏障功能的损伤,减轻内毒素血症。 相似文献
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Coping and immunosuppression: inescapable but not escapable shock suppresses lymphocyte proliferation 总被引：10，自引：0，他引：10
M L Laudenslager S M Ryan R C Drugan R L Hyson S F Maier 《Science (New York, N.Y.)》1983,221(4610):568-570
Rats were given series of escapable shocks, identical inescapable shocks, or no shock. The subjects were reexposed to a small amount of shock 24 hours later, after which an in vitro measure of the cellular immune response was examined. Lymphocyte proliferation in response to the mitogens phytohemagglutinin and concanavalin A was suppressed in the inescapable shock group but not in the escapable shock group. This suggests that the controllability of stressors is critical in modulating immune functioning. 相似文献
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Under the conditions specified, chicks fail to learn either to escape or to avoid shock on the day of hatching. Chicks trained for the first time on the day after hatching quickly learn to escape but do not learn to avoid shock. Avoidance learning first appears on the third day of life, and from that time the number of chicks learning to avoid increases with age, so that by the fifth day of life the majority are able to do so. 相似文献
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超迟播稻茬小麦播种量·施氮量和氮肥运筹方式 总被引：1，自引：0，他引：1
[目的]研究超迟播稻茬小麦适宜的播种量、施氮量、氮肥运筹方式。[方法]研究不同处理的基本苗及产量构成,比较了不同氮肥运筹方式下的成穗数、每穗实粒数、千粒重、产量。[结果]不同的播种量、施氮量、氮肥运筹方式对成穗数、每穗实粒数、千粒重、产量有极显著影响。播种量每增加15 kg/hm~2,成穗数增加10.65万穗/hm~2、千粒重减少0.22 g、产量增加150.45 kg/hm~2;施氮量每增加15 kg/hm~2N,实粒数增加1.07个、产量增加450.75 kg/hm~2。氮肥运筹方式的影响随播种量、施氮量的变化而变化。产量最高的氮肥运筹方式是播种量480 kg/hm~2时"轻施返青肥,重施基肥和拔节肥"方式、施氮量240 kg/hm~2N时"氮肥后移、返青肥和孕穗肥等量"方式。[结论]该研究为超迟播稻茬小麦的推广提供了理论基础。 相似文献
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基于二级LTP纹理颜色直方图的动物实时跟踪 总被引：1，自引：0，他引：1
目标表征方法是目标跟踪算法当中的关键环节.近来,目标跟踪技术在动物的跟踪以及其他农业领域当中得到广泛应用.但是,只对区域进行一次纹理特征的提取往往不够丰富.因此,对原始提取LTP纹理特征的方法进行改进,提出二级提取LTP特征融合的目标表征方法.通过对原始图像进行相同LTP特征提取,得到目标区域的多级LTP图像特征,将HSV模型中受光照影响较小的H分量作为颜色特征向量,来建立每一级特征相应的直方图.根据嵌入到Mean Shift当中的二级纹理颜色模型来进行动物跟踪.与传统的基于核的跟踪算法进行对比,此方法显著提高动物目标跟踪的鲁棒性. 相似文献
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Years of intensive investigation have yielded a sophisticated understanding of long-term potentiation (LTP) induced in hippocampal area CA1 by high-frequency stimulation (HFS). These efforts have been motivated by the belief that similar synaptic modifications occur during memory formation, but it has never been shown that learning actually induces LTP in CA1. We found that one-trial inhibitory avoidance learning in rats produced the same changes in hippocampal glutamate receptors as induction of LTP with HFS and caused a spatially restricted increase in the amplitude of evoked synaptic transmission in CA1 in vivo. Because the learning-induced synaptic potentiation occluded HFS-induced LTP, we conclude that inhibitory avoidance training induces LTP in CA1. 相似文献
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目的探讨动态监测感染性休克患儿血小板（PLT）计数及平均血小板体积（MPV）的临床意义。方法检测53例感染性休克患儿（代偿期38例,失代偿期15例）入院后1、24、72、120h的PLT计数、MPV,并与同期50例健康儿作对照。结果感染性休克患儿入院时PLT计数低于对照组,而MPV高于对照组（P〈0.01）,其中失代偿期组更明显。死亡组PLT计数在各时点均低于存活组,但MPV均高于存活组（P〈0.01）。结论感染性休克患儿PLT计数、MPV的动态变化有助于判断病情严重程度及预后。 相似文献
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Mice were shocked with 0.1, 0.3, or 0.5 ma of current at 2 to 3, 8 to 9, or 15 to 16 days. Handled, nonshocked and nonhandled controls were also used. In adulthood each group was split into thirds and taught an avoidance response under shock of 0.3, 0.5, or 0.7 ma. The amount of shock given during infancy and adulthood, and the age at which shock occurred, were all found to have significant effects upon learning. 相似文献
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Pigeons were trained to peck a key to escape a pulsing shock of linearly increasing intensity. As the rate of increase was varied from 0.0374 milliamperes per minute to 37.4 milliamperes per minute, the intensity at which most pecking occurred varied from 2.2 to 5.0 milliamperes. 相似文献
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Kivelson MG Kennel CF McPherron RL Russell CT Southwood DJ Walker RJ Hammond CM Khurana KK Strangeway RJ Coleman PJ 《Science (New York, N.Y.)》1991,253(5027):1518-1522
During the 10 February 1990 flyby of Venus, the Galileo spacecraft skimmed the downstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed. 相似文献
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Pastalkova E Serrano P Pinkhasova D Wallace E Fenton AA Sacktor TC 《Science (New York, N.Y.)》2006,313(5790):1141-1144
Analogous to learning and memory storage, long-term potentiation (LTP) is divided into induction and maintenance phases. Testing the hypothesis that the mechanism of LTP maintenance stores information requires reversing this mechanism in vivo and finding out whether long-term stored information is lost. This was not previously possible. Recently however, persistent phosphorylation by the atypical protein kinase C isoform, protein kinase Mzeta (PKMz), has been found to maintain late LTP in hippocampal slices. Here we show that a cell-permeable PKMz inhibitor, injected in the rat hippocampus, both reverses LTP maintenance in vivo and produces persistent loss of 1-day-old spatial information. Thus, the mechanism maintaining LTP sustains spatial memory. 相似文献
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Long-term potentiation in dentate gyrus: induction by asynchronous volleys in separate afferents 总被引：1，自引：0，他引：1
Long-term potentiation (LTP), a long-lasting enhancement of synaptic efficacy, is considered a model for learning and memory. In anesthetized rats, activation of dentate granule cells by stimulating either the medial or lateral perforant pathway at frequencies of 100 to 400 Hz produced LTP of the stimulated pathway preferentially at 400 Hz. However, hippocampal pathways do not normally fire at this high rate. Stimuli at 200 Hz were then applied to either the medial or lateral pathway separately, to both pathways simultaneously, or to the two pathways asynchronously so that the composite stimulus applied to the granule cell dendrite was 400 Hz. LTP was produced preferentially in the asynchronous condition. Thus, lower frequency, physiological input volleys arriving asynchronously at medial and lateral synapses can induce LTP by activating a 400-Hz sensitive mechanism capable of integrating spatially separated granule cell inputs. This may reflect how LTP is normally produced in the dentate gyrus. 相似文献
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We examined the amount of theta rhythm (4 to 9 hertz) in cortical electroencephalograms of rats for 30 minutes after training in one-trial tasks. Some animals received electroconvulsive shock after training. The amount of theta in the electroencephalogram after training was positively correlated with the degree of subsequent retention of a footshock, whether animals had received electroconvulsive shock or not. 相似文献
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Puromycin and retention in the goldfish 总被引：1，自引：0，他引：1
A first experiment compared the behavior of goldfish injected with puromycin immediately after each of a weekly series of brief discriminative training sessions in the shuttlebox to that of appropriate controls. Discrimination was not prevented, nor was escape from shock impaired, but probability of response to the conditioned stimuli, both positive and negative, was reduced substantially. These results suggest that puromycin interferes with the consolidation of conditioned fear. The null outcome of a second experiment, in which all training was given in a single long session instead of a series of short sessions, suggests (contrary to recent indications) that consolidation begins in the training session. The conditioned-fear hypothesis is supported by the results of a third experiment in which the animals were shocked upon entering a goalbox to which they had previously learned to swim for food; animals injected with puromycin, immediately after the shock, entered the goalbox more readily 1 week later than did appropriate controls. 相似文献
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李跃 《湖南农业大学学报(自然科学版)》2012,38(3):310-313
设对照组(未染毒)、低剂量组(约2.5支烟,每天染毒10 min)、中剂量组(约5支烟,每天染毒20 min)及高剂量组(约10支烟,每天染毒40 min)4个处理,将雄性SD大鼠置于气体染毒箱内行被动吸烟,研究卷烟烟气暴露对大鼠学习记忆功能及海马病理和脑源性神经营养因子(brain-derived neurotrophicfactor,BDNF)的影响。结果表明:染毒30 d,染毒组大鼠潜伏时间均显著短于对照组,BDNF表达显著高于对照组;染毒60 d,中剂量组大鼠潜伏时间显著短于对照组,BDNF表达显著高于对照组;染毒180 d,染毒组大鼠潜伏时间显著长于对照组,BDNF表达显著高于对照组;不同剂量处理大鼠的海马HE染色均无明显变化,大鼠的海马组织均无器质性损伤;短期烟气暴露可提高大鼠学习记忆功能,随染毒时间的延长,大鼠学习记忆功能下降,该作用与海马BDNF的表达密切相关。 相似文献
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Postsynaptic calcium is sufficient for potentiation of hippocampal synaptic transmission 总被引：31，自引：0，他引：31
Brief repetitive activation of excitatory synapses in the hippocampus leads to an increase in synaptic strength that lasts for many hours. This long-term potentiation (LTP) of synaptic transmission is the most compelling cellular model in the vertebrate brain for learning and memory. The critical role of postsynaptic calcium in triggering LTP has been directly examined using three types of experiment. First, nitr-5, a photolabile nitrobenzhydrol tetracarboxylate calcium chelator, which releases calcium in response to ultraviolet light, was used. Photolysis of nitr-5 injected into hippocampal CA1 pyramidal cells resulted in a large enhancement of synaptic transmission. Second, in agreement with previous results, buffering intracellular calcium at low concentrations blocked LTP. Third, depolarization of the postsynaptic membrane so that calcium entry is suppressed prevented LTP. Taken together, these results demonstrate that an increase in postsynaptic calcium is necessary to induce LTP and sufficient to potentiate synaptic transmission. 相似文献