HIV-1 gp120对鼠海马长时程增强效应的影响

为了探讨人类免疫缺陷病毒Ⅰ型(HIV-1)的包膜糖蛋白gp120对鼠海马脑片CA1区的突触传递及可塑性的影响,应用离体脑片记录技术,记录大鼠海马CA1区的兴奋性突触后电位(excitatory postsynaptic potential,EPSP),研究了gp120对高频电刺激Schaffer侧支引起的鼠长时程增强效应(long-term potentiation,LTP)的影响.结果发现:gp120对大鼠海马CA1区LTP产生抑制作用,对其基础EPSP没有影响,而且这种抑制效应随着gp120浓度增大而增强,即具有剂量依赖性.PKA/PKC蛋白激酶抑制剂H7可以反转这种抑制效应.提示:gp120可能是通过抑制海马CA1区的LTP而参与艾滋病相关性痴呆(HIV-1 associated dementia,HAD)的形成.     

皮质酮对大鼠海马脑片CA1区长时程增强效应的影响

目的：探讨糖皮质激素对海马神经突触可塑性的影响。方法：高浓度（10^-5mol/L)皮质酮直接作用于大鼠海马脑片,记录CA1区LTP）。结果：海马脑片CA1区LTP的形成受到抑制。结论：应激时过量糖皮质激素会直接影响海马神经突触可塑性。     

PAF受体在铝抑制海马CA3区长时程增强中的作用

目的 :观察PAF受体在铝抑制海马CA3区长时程增强 (longtermpotentiation ,LTP)中的作用。 方法 :应用细胞外电生理记录方法 ,通过向海马CA3区分别微量注射血小板活化因子 (PlateletactivatingfactorPAF)受体拮抗剂银杏内酯B(GinkgolideB)和激动剂mc PAF ,以群体锋电位 (populationspikesPS)幅度为指标 ,观察PP CA3通路的LTP变化。结果 :① 0 .2 μmol/L的银杏内酯B对CA3区的诱发电位无影响 ,但可抑制CA3区的LTP。② 0 .2 5mol/L的三氯化铝不影响CA3区LTP ,但可加强银杏内酯B的抑制作用。③ 4 0 μmol/Lmc PAF对强直刺激引起的LTP无影响 ,却可减轻 0 .5mol/L三氯化铝的对LTP的抑制作用。结论 :PAF受体在刺激PP诱发的CA3区LTP中起作用 ,而金属铝对CA3区LTP的抑制作用至少部分与PAF受体有关。     

锂对铅引起的大鼠海马CA1区长时程增强效应（LTP）损伤的修复作用

应用离体脑片记录技术,记录大鼠海马CA1区的兴奋性突触后电位(EPSPs),研究了锂对铅引起的大鼠海马CA1区长时程增强效应(long-termpotentiation,LTP)损伤的修复作用。结果表明:对照组大鼠海马CA1区LTP幅度为194.42±14.05%(n=10);铅处理组LTP的幅度为147.06±9.55%(n=13);而锂加铅处理组LTP的幅度为193.45±14.91%(n=15)。与对照组相比,铅处理组LTP的幅度降低了47.36%,而锂几乎完全修复了铅对大鼠海马CA1区LTP幅度的损伤。锂和铅处理后对大鼠海马CA1区的双脉冲易化(paired-pulsefacilica-tion,PPF)都有一定的抑制作用,在脉冲间隔为50ms时,这种抑制效应最大:对照组为155.58±6.35%(n=7);铅暴露组为150.26±13.74%(n=8);锂加铅处理组为140.59±15.42%(n=8)。结果表明:锂对铅引起大鼠海马CA1区LTP的损伤有一定的修复作用。     

外侧隔—海马CA1通路电生理分析

电刺激外侧隔区可在海马 CA1区锥体细胞层记录到群锋电位,在 CA1辐射层顶树突记录到兴奋性突触后电位(EPSP)。侧脑室注射微量海人酸损毁海马 CA3-CA4区锥体细胞后,电刺激外侧隔区在 CA1顶树突不再诱发 EPSP,由此认为外侧隔-CA1顶树突的神经联系是通过同侧海马 CA3锥体细胞侧支实现的。但 CA3-CA4损毁后,电刺激外侧隔区在海马 CA1起层锥体细胞底树突仍可记录到 EPSP。这一在正常情况下被掩盖的外侧隔-CA1底树突神经联系及其来源尚有待探讨。     

钩藤对致痫大鼠海马脑片诱发场电位的影响

目的研究钩藤对癫痫模型海马脑片诱发场电位的影响。方法以毛果芸香碱致痫大鼠为实验对象,采用脑片旁滴注给药,用细胞外玻璃微电极记录方法,观察钩藤对癫痫模型离体海马脑片CA1区锥体细胞诱发群锋电位（populationspike,PS）的影响。结果给予钩藤后使致痫大鼠海马脑片PS幅度平均降低27.64％,平均8.71min恢复(n=14,P<0.01)。结论钩藤能降低致痫大鼠海马脑片CA1区顺向诱发PS幅度,提示钩藤对中枢神经系统的突触传递过程有明显的抑制效应,具有抗癫痫作用。     

大鼠在体海马CA1区场电位引导新技术——刺激/记录/给药一体化装置的开发和应用

大鼠海马场电位记录是研究学习记忆的一个重要手段,尤以在体记录更具生理学意义.为克服目前在体海马场电位记录的弊端和诸多不便,提高实验效率,设计并完善了一套简便易行,融刺激、记录、给药于一体的大鼠海马在体CA1区场电位实验技术.将雄性SD大鼠麻醉后固定于脑立体定位仪上,利用自制的刺激/记录/给药联合装置,引导海马CA1区场兴奋性突触后电位(fEPSP).结果表明,使用刺激/记录/给药联合装置能长时间稳定记录由测试刺激诱发的海马CA1区fEPSP.高频刺激条件下,能成功诱导早期时相长时程增强(E-LTP)和晚期时相型长时程增强(L-LTP).海马内注射AMPA受体阻断剂CNQX(100μmol/L,1μl)可迅速抑制fEPSP,注射NMDA受体拮抗剂AP-5(100μmol/L,1μl)可明显压抑LTP,药物发挥作用的时间较侧脑室给药明显缩短,剂量减少.采用此联合装置还成功实现了PPF的稳定记录.总之,采用刺激/记录/给药一体化技术进行在体海马CA1区场电位记录的特点是简单、可靠、高效,可以为开展脑认知功能活动的电生理学研究奠定良好的基础.     

低频刺激诱发海马突触传递去长时程增强的特性研究

目的和方法：以频率为1、3或5Hz,脉冲数为300或900,与高频刺激（HFS）时间间隔是20min或100min的低频刺激（LFS）作用于大鼠海马脑片,分别观察其对CA1区突触传递去长时程增强（DP）形成的影响。结果：HFS（100Hz,100脉冲的串刺激两串,串间隔30s)可诱发突触传递效率的长时程增强（LTP）。HFS经20min给予3Hz900脉冲的LFS可翻转LTP,产生DP,该作用可为NMDA受体阻断剂AP5（50μmol/L)所阻断,1Hz、5Hz、低脉冲数或与HFS时间间隔长的LFS,其诱发DP的效率减弱。结论：诱发海马CA1区DP的产生,对LFS的参数有较强的依从性。该作用可能是通过激活NMDA受体而实现的。     

大鼠海马CA1区β受体参与长时程增强和空间学习

在离体海马脑片上, 激活CA1区β肾上腺素能受体(β受体)易化这一区域突触传递的长时程增强(LTP). 然而, 在体情况下, CA1区β受体是否参与LTP的调控, 是否参与海马依赖性的学习和记忆, 尚无实验证据. 为此, 观察了β受体激动剂异丙肾上腺素或拮抗剂心得安对在体CA1区LTP的调控作用以及对大鼠在Morris水迷宫中的空间学习的影响. 正常情况下对突触强度仅有微小调制作用的10 Hz的θ节律刺激(每串150个脉冲, 1串), 在CA1区局部给予L-异丙肾上腺素后, 显著地诱导出LTP, 这一效应被DL-心得安所阻断; 相反, 正常情况下对突触强度有显著调制作用的5 Hz的θ节律刺激(每串150个脉冲, 3串), 在CA1区局部给予DL-心得安后, 诱导出的LTP显著地被压抑. 相应地, 训练前20 min在CA1区注射DL-心得安, 大鼠在水迷宫中的学习速度显著地慢于对照组大鼠, 训练后24 h的空间记忆保持亦相应较差. 以上结果表明, β受体参与海马CA1区的突触可塑性, 且对空间学习重要.     

姜黄素预防高原缺氧大鼠认知功能障碍的电生理机制

目的:探讨姜黄素(curcumin)预防高原缺氧大鼠认知功能障碍的电生理机制。方法:将30只成年雄性SD大鼠随机分为健康对照组、模型组(Model组)、姜黄素[按体重60mg/(kg.d)]治疗组(curcumin组)。造模后,检测脑片水平的海马的LTP变化,并运用膜片钳技术检测海马CA1区神经元的电生理变化。结果:(1)给予HFS刺激后各组均可诱发LTP并持续1h以上,与对照组比较模型组组HFS刺激后LTP明显被抑制(P<0.05),姜黄素可减轻缺氧所致的LTP抑制(P<0.05);(2)高原缺氧使海马CA1神经元阈电位升高,动作电位(AP)数量减少,兴奋性降低,姜黄素干预可明显减轻高原缺氧对细胞神经元的抑制。结论:姜黄素可显著改善高原缺氧大鼠认知功能障碍,其可能机制是通过维持海马CA1细胞的兴奋性减轻高原缺氧对认知功能的损伤。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.