液压打击损伤后海马CA1区神经元兴奋性变化的研究

为考察脑损伤对海马CA1区锥体神经元电活动的影响并研究大黄素对神经元的超兴奋性和突触传递的作用,应用液压打击大鼠脑损伤模型和细胞外记录方法提取诱发的海马CA1区场兴奋性突触后电位(fPSP)和群峰电位(PS),进行相关的数据处理和分析。发现损伤侧比非损伤侧的fPSP斜率明显升高,PS波峰个教显著增加,而PS潜伏期明显减小;在灌流液中施加大黄素,CA1区诱发场电位明显减弱。研究结果表明：颅脑损伤可造成海马CA1区锥体神经元的迟发性过度兴奋;大黄素对神经元的兴奋性有抑制作用,可能对颅脑损伤后的中枢神经系统具有保护功能。     

新型雌激素受体ER-α36在新生与成年大鼠海马和皮层中表达的比较北大核心CSCD

ER-α36是一种新型雌激素受体亚型,广泛分布于乳腺、子宫、消化道、呼吸道等组织和细胞中。本文旨在研究ER-α36在中枢神经系统中的表达和分布情况。采用免疫细胞/组织化学方法和蛋白质免疫印迹杂交比较ER-α36在新生(1日龄)与成年(12周龄)Sprague-Dawley(SD)大鼠海马及皮层区的表达和分布情况。研究显示,ER-α36在成年大鼠海马及皮层区均有表达,主要分布于锥体神经元。ER-α36在新生大鼠海马和皮层神经元中均定位于细胞膜。新生大鼠皮层神经元ER-α36蛋白表达高于海马,而成年大鼠皮层神经元ER-α36蛋白表达低于海马。与新生大鼠相比较,成年大鼠海马和皮层神经元ER-α36表达均显著提高。以上结果提示,ER-α36参与介导神经元膜雌激素信号通路的调节,且在大鼠出生后海马及皮层发育中发挥着重要作用。因此,ER-α36可能为学习记忆、神经系统退行性疾病等的防治提供潜在的药物靶点。     

大鼠全脑缺血后海马CA1区锥体神经元L型钙通道电流的改变(英文)

已有研究表明在脑缺血期间及再灌流后早期,海马CA1锥体神经元细胞内钙浓度明显升高,这一钙超载被认为是缺血性脑损伤的重要机制之一.电压依赖性钙通道是介导正常CA1神经元钙内流的主要途径.实验观察了脑缺血再灌流后早期海马CA1锥体神经元电压依赖性L型钙通道的变化.以改良的四血管闭塞法制作大鼠 15min前脑缺血模型,在急性分离的海马CA1神经元上,采用膜片钳细胞贴附式记录L型电压依赖性钙通道电流.脑缺血后CA1神经元L型钙通道的总体平均电流明显增大,这是由于通道的开放概率增加所致.进一步分析单通道动力学显示,脑缺血后通道的开放时间变长,通道的开放频率增大.研究结果提示L型钙通道功能活动增强可能参与了缺血后海马CA1锥体神经元的细胞内钙浓度升高     

成年大鼠海马CA1区锥体细胞K_(ATP)通道的特性

为了解成年大鼠海马CA1区锥体细胞KATP 通道的特性 ,实验采用膜片钳技术的内面向外式记录法 ,在急性分离的CA1区锥体神经元上 ,研究了可被胞浆侧ATP所抑制的钾离子单通道的特性。当细胞膜内外两侧的K 浓度均为 14 0mmol/L时 ,通道的电导为 63pS ,翻转电位为 1 71mV ,通道呈弱内向整流性。在负钳制电位时 ,通道开放时常被短时程的关闭所打断 ,而在正钳制电位时 ,这种短时程的关闭状态明显少于负钳制电位时。但通道开放概率未见明显的电压依赖性。ATP对通道活动的抑制作用呈浓度依赖性 ,抑制通道活动 5 0 %的ATP浓度为 0 1mmol/L。KATP 通道的特异性阻断剂tolbutamide (甲糖宁 ,1mmol/L)可完全阻断通道的活动 ,而KATP 通道开放剂diazoxide (二氮嗪 ,1mmol/L)则不增强通道的活动。     

成年大鼠海马CA1区锥体神经元外向整流氯离子单通道特性

采用膜片钳内面向外式技术,在急性分离成年大鼠海马CAl区锥体细胞上记录到了外向整流氯离子通道（outwardly rectifying chloride channel,ORCC）.长时间去极化（≥60 mV）刺激后,在30%的游离膜片上记录到有外向整流特性的单通道氯电流,膜电位在－60 mV到0 mV之间的单通道电导为(16.58±1.54) pS（n=10）,而在0 mV到+60 mV之间电导为（40.92±3.17） pS.通道开放概率有明显的电压依赖性(膜电位－60 mV时,P_o=0.44±0.12;膜电位为+60 mV时,P_o=0.86±0.06, n=10).在对称Cl^－浓度（150 mmol/L）时,通道翻转电位为(－4.17±1.84) mV.当溶液中部分NaCl被葡萄糖酸钠替代后,翻转电位为：(－34.23±4.86) mV (［Cl^－］_i/［Cl^－］_o=(30 mmol/L)/(150 mmol/L)),接近氯离子通道的理论值,这表明通道具有氯离子选择性.浴槽液中分别加入氯通道阻断剂DIDS和SITS可以使+40 mV的通道开放概率从(0.83±0.06)和(0.86±0.06)分别降低到(0.12±0.05)和(0.13±0.04)（n=5）,冲洗后可使开放概率基本恢复.上述研究结果显示,在成年大鼠海马CA1神经元上存在外向整流氯离子通道.     

成年大鼠海马CA1区锥体细胞KATP通道的特性

为了解成年大鼠海马CA1区锥体细胞KATP通道的特性,实验采用膜片钳技术的内面向外式记录法,在急性分离的CA1区锥体神经元上,研究了可被胞浆侧ATP所抑制的钾离子单通道的特性,当细胞膜内外两侧的K^ 浓度均为140mmol/L时,通道的电导为63pS,翻转电位为1．71mV,通道呈弱向内向整流性,在负钳制电位时,通道开放时常被短时的关闭所打断,而在正钳制电位时,这种短时程的关闭状态明显少于负钳制电位时,但通道开放概率未见明显的电压依赖性,ATP对通道活动的抑制作用呈浓度依赖性,抑制通道活动50％的ATP浓度为0．1mmol/L.KATP通道的特异性阻断剂tolbutamide(甲糖宁,1mmol/L)可完全阻断通道的活动,而KATP通道开放剂diazoxide(二氮嗪,1mmol/L）则不增强通道的活动。     

二氧化硫衍生物对大鼠海马CA3区神经元瞬间外向钾电流的影响

为研究二氧化硫(SO2)衍生物——NaHSO3和Na2SO3(二者分子比为1：3)对大鼠海马CA3区神经元瞬间外向钾电流(IA)的影响,利用全细胞膜片钳技术,根据动力学和药理学特性分离鉴定大鼠海马CA3区神经元IA,观察SO2衍生物对IA的效应。发现SO2代谢衍生物可浓度依赖性地增大IA,使IA增大50％的剂量为25μmol/L。此外还与电压呈依赖关系,但不具有频率依赖性。10μmol/L的SO2代谢衍生物不影响IA电流的激活过程,但升高了A-通道稳态失活电压,延长了A-电流失活时间。说明SO2代谢衍生物可增大大鼠海马CA3区神经元IA电流,延长A-电流的失活时间,从而影响海马神经元的膜生理感应,这可能是SO2影响神经细胞功能的机理之一。     

小功率WPT电磁环境对海马CA1区神经元兴奋性的影响

该研究旨在探究小功率无线电能传输(wireless power transmission,WPT)系统对小鼠海马CA1区神经元兴奋性的影响。将小鼠分为对照组和辐射组(2周组、4周组、6周组),通过莫里斯水迷宫实验、光纤光度实验、HE染色实验、膜片钳实验观察小鼠工作记忆能力、Ca²⁺信号强度、海马锥体细胞数量、动作电位的变化以及瞬时外向K⁺通道电流(I_A)和延迟整流K⁺通道电流(I_K)的变化。莫里斯水迷宫实验结果显示,小功率WPT电磁环境不会对小鼠的工作记忆能力产生影响;光纤光度实验以及HE染色实验显示,小功率WPT电磁环境可能促进了海马CA1区神经元集群的放电活动,导致了荧光信号强度的增加。这表明电磁环境对Ca²⁺浓度的调节可能增加了海马CA1区神经元放电活动次数,增强了海马CA1区神经元的兴奋性。随着辐射时间的增加,荧光信号的峰值逐渐下降,表明小鼠海马锥体细胞适应了小功率WPT电磁环境;小功率WPT电磁环境提高了小鼠海马CA1区的神经元的静息膜电位,缩短...     

大鼠海马CA1区锥体神经元I_A和I_K在出生后早期的变化

大脑快速发育期(brain growth spurt,BGS)是神经元生长、突触连接的关键时期;电压门控性K+通道是维持细胞兴奋性和神经元间信息传递的关键通道。本文旨在探究BGS期内大鼠海马CA1区锥体神经元电压门控性K+通道电流及其通道动力学特性的变化,以期找出大鼠海马CA1区锥体神经元电压门控性K+通道发育的关键期。采用全细胞膜片钳技术,研究出生后0~4周大鼠海马CA1区脑片上的锥体神经元全细胞电压门控性K+通道电流及其通道动力学特性。结果显示:在测试电压为+90mV下,以出生后0周为参照,出生后1~4周的瞬时外向K+通道电流(IA)的最大电流密度的增幅分别为(16.14±0.51)%、(81.73±10.71)%、(106.72±5.29)%、(134.58±8.81)%(n=10,P<0.05);延迟整流K+通道电流(IK)的最大电流密度增幅分别为(16.75±3.88)%、(134.01±2.85)%、(180.56±8.49)%、(194.5±8.53)%(n=10,P<0.05),显示K+通道电流密度于1~2周增幅最大;IA的激活曲线向左移,半数激活电压随周龄增加逐渐减小,分别为14.67±0.75、13.46±0.64、8.39±0.87、4.60±0.96、0.54±0.92(mV,n=10,P<0.05);IK的激活曲线向左移,半数激活电压随周龄增加逐渐减小,分别为8.94±0.85、6.65±0.89、0.47±1.15、1.80±0.89、8.56±1.08(mV,n=10,P<0.05)。IA的失活曲线向左移,0周龄与1周龄之间的半数失活电压没有显著性差异,而出生后1~4周随周龄增加半数失活电压逐渐减小(P<0.05),分别为45.68±1.26、46.81±0.78、48.64±0.81、51.96±1.02、58.31±1.35(mV,n=10)。以上结果表明,随着鼠龄的增加,IA和IK电流密度逐渐增加,电压门控性K+通道半数激活、失活电压降低,尤其是出生后1周至2周变化明显,上述变化与海马神经元的逐渐发育成熟及其功能的完善有关。     

大鼠全脑缺血后海马CA1区锥体神经元L型钙通道电流的改变(英)

已有研究表明在脑缺血期间及再灌流后早期,海马CA1锥体神经元细胞内钙浓度明显升高,这一钙超载被认为是缺血性脑损伤的重要机制之一.电压依赖性钙通道是介导正常CA1神经元钙内流的主要途径.实验观察了脑缺血再灌流后早期海马CA1锥体神经元电压依赖性L型钙通道的变化.以改良的四血管闭塞法制作大鼠15 min前脑缺血模型,在急性分离的海马CA1神经元上,采用膜片钳细胞贴附式记录L型电压依赖性钙通道电流.脑缺血后CA1神经元L型钙通道的总体平均电流明显增大,这是由于通道的开放概率增加所致.进一步分析单通道动力学显示,脑缺血后通道的开放时间变长,通道的开放频率增大.研究结果提示L型钙通道功能活动增强可能参与了缺血后海马CA1锥体神经元的细胞内钙浓度升高.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

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     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.