Cobalt-dependent potentiation of net inward current density in Helix aspersa neurons.

A low concentration of transition metal ions Co2+ and Ni2+ increases the inward current density in neurons from the land snail Helix aspersa. The currents were measured using a single electrode voltage-clamp/internal perfusion method under conditions in which the external Na+ was replaced by Tris+, the predominant external current carrying cation was Ca2+, and the internal perfusate contained 120 mM Cs+/0 K+; 30 mM tetraethylammonium (TEA) was added externally to block K+ current. In the presence of Co2+ (3 mM) or Ni2+ (0.5 mM) inward Ca2+ currents were stimulated normally by voltage-dependent activation of Ca2+ channels. There was a 5-10% decrease in the rate of rise of the inward current. The principal effect of Co2+ and Ni2+ in increasing the current density seems to be a decrease in the rate at which the inward currents decline during a depolarizing voltage pulse. The results may be due to a decrease in a voltage-dependent or Ca(2+)-dependent outward current and/or an inhibition of Ca2+ channel inactivation. Outward current under these conditions (zero internal K+) was significant and most likely due to Cs+ efflux through the voltage-activated or Ca(2+)-activated nonspecific cation channels. Co2+ is an extremely effective blocker of this outward current. These results are not an artifact of internal perfusion or the special ionic conditions. Intracellular recording of unperfused neurons in normal Helix Ringer's solution showed that the Ca(2+)-dependent action potential duration was increased significantly by low concentrations of Co2+. This result is consistant with the Co(2+)-dependent increase in inward (depolarizing) current seen in voltage-clamp experiments.     

Analysis of a decreased Na+ conductance by tumor necrosis factor in identified neurons of Aplysia kurodai.

The ionic mechanisms of the effect of extracellularly ejected recombinant human tumor necrosis factor-alpha (rhTNF-alpha) on the membrane of identified neurons R9 and R10 of Aplysia kurodai was investigated with conventional voltage-clamp, micropressure ejection, and ion substitution techniques. Micropressure-ejected rhTNF caused a marked hyperpolarization in the unclamped neuron. Clamping the same neuron at it resting potential level (-60 mV) and reejecting rhTNF-alpha with the same dose produced a slow outward current [Io (TNF)] associated with a decrease in input membrane conductance. Io (TNF) was decreased by depolarization and increased by hyperpolarization. The extrapolated reversal potential of Io (TNF) was approximately +10 mV. Ion substitution and pharmacological experiments suggest that Io (TNF) in identified neurons R9 and R10 of A. kurodai is due to a decreased Na+ conductance but not due to an activation of the Na(+)-K+ pump. Our results demonstrate that the immunomodulator TNF can act directly on the nervous system as well as on the immune system.     

硒对沙土鼠脑缺血再灌注的保护作用及其作用机制研究

目的 研究亚硒酸钠对沙土鼠脑缺血再灌注损伤的保护作用及其机制。方法 将50只沙土鼠随机分为5组，Ⅰ组：假手术组；Ⅱ组：缺血灌注1天处死组；Ⅲ组：缺血再灌注4天处死组；Ⅳ组：硒处理、缺血再灌1天处死组；Ⅴ组：硒处理、缺血再灌注4天处死组。采用夹闭双侧颈动脉法制备沙土鼠脑缺血再灌注模型，焦油紫染色，光镜下观察各组海马CAl区神经细胞的形态变化，电镜下超微结构变化。同时测定脑组织中丙二醛(MDA)、谷胱甘肽过氧化酶(GSH-PX)、超氧化物歧化酶(SOD)的含量。结果 硒处理组沙土鼠脑缺血再灌注后，神经细胞病理形态损伤较轻，SOD、GSH-PX含量较高，MDA含量较低。结论 硒对沙土鼠脑缺血再灌注损伤具有保护作用，其机制可能和增强脑缺血再灌注早期脑组织中SOD、GSH-PX的活性，抑制氧自由基损伤，减轻脂质过氧化反应有关。     

磷脂酶A2激活在鼠急性缺血性脑损伤中的作用机制

目的 探讨急性脑缺血后脑组织内磷脂酶A2（PLA2）激活及细胞内[Ca^2 ]i与脑损伤的关系，为预防和治疗急性缺血性脑损伤提供理论基础和新的思路。方法 将局灶性脑缺血模型大鼠分5组（假手术组、缺血30、60、90、120min组），测定脑组织PLA2活力、脑细胞[Ca^2 ]i、脑含水量及缺血120min组脑组织PLA2表达量的改变。结果 脑缺血120min脑组织PLA2活性、[Ca^2 ]i、脑含水量较假手术组明显升高，并与时间呈正相关，缺血120min后脑组织中出现sPLA2-ⅡAmRNA表达，且cPLA2-ⅣmRNA表达水平较假手术组明显增强。结论 磷脂酶A2激活参与了脑缺血后神经细胞内钙超载及脑损伤的整人病理过程。     

离子色谱法测定硫酸软骨素的含量

建立了用离子色谱法测定硫酸软骨素的方法。在６ｍｏｌ／Ｌ盐酸介质中将硫酸软骨素水解生成等摩尔的硫酸根离子，然后用ＡｎｉｏｎＨＣ离子色谱柱进行分离，以硼酸钠／葡萄糖酸钠淋洗液为流动相，流速１．５ｍｌ／ｍｉｎ，电导检测器检测。硫酸根离子在０．００１～０．０８０ｍｇ／ｍｌ浓度范围内线性关系良好，相关系数为０．９９９４，最低检测浓度为０．０００６ｍｇ／ｍｌ。样品中硫酸根离子的加样回收率为９８．５１％～９９．５２％，硫酸软骨素原料药和注射液及鲨鱼软骨粉胶囊中硫酸软骨素测定的相对标准偏差分别为０．２５％，１．０６％和１．９６％。该方法已应用于多种硫酸软骨素制剂中硫酸软骨素的含量测定     

甲醛对小鼠肺组织超氧化物歧化酶活性、丙二醛含量的影响

目的　探讨甲醛对小鼠肺组织超氧化物歧化酶 (SOD)活性、丙二醛 (MDA)含量的影响。方法　将 36只小鼠随机分成对照组和 2 0、4 0、6 0、80、1 0 0mg m3剂量组 ,采用静式呼吸道染毒 ,连续染毒 35d ,每天 2h ,染毒结束后将小鼠处死 ,测定其肺组织SOD活性 ,MDA含量。结果　与对照组相比 ,各剂量组小鼠肺组织内SOD活性均明显降低 ,MDA含量均明显升高 (P <0 0 1 )。且各剂量组之间SOD活性随染毒剂量的增加而降低 ,MDA含量随染毒剂量的增加而增加 ,但受试物组间经统计学比较差异无显著性 (P >0 0 5 )。结论　吸入一定浓度甲醛即可引起小鼠肺组织SOD活性、MDA含量产生明显变化     

Model Features of a Cardiac lontophoretic Drug Delivery Implant

Pharmaceutical Research -     

51例早孕妇女绒毛超氧化物歧化酶测定结果分析

本文采用改良的邻革之酚自氧化法,对51例无遗传性疾病早孕妇女绒毛细胞进行了SOD活力测定。其比活力为426.2±48.4u/mg蛋白(x±SD),测定值范围为217.2～589.1u/mg蛋白,P95>915.0u/mg蛋白。     

老年轻度认知功能损害患者血清维生素E、超氧化物歧化酶和丙二醛的测定及临床意义

目的　了解轻度认知功能损害 (MCI)患者血清维生素E(VitE)、超氧化物歧化酶 (SOD)和丙二醛(MDA)的水平 ,探讨其变化的临床意义。方法　采用 1∶1配对病例对照设计 ,受试者均于晨 7时空腹抽静脉血 ,应用紫外分光光度法测定了 4 5例老年MCI患者和 4 5例健康老年人血清VitE ,SOD和MDA的含量。结果　老年MCI患者血清VitE含量及SOD活性显著低于健康老年人 (P <0 .0 1) ,血清MDA含量显著高于健康老年人 (P <0 .0 1)。结论　以MDA为代表的自由基代谢产物参与了MCI的病理生理过程 ;临床上应给予外源性VitE以进行早期干预治疗。     

离子对提取比色法测定复方制剂中氨基比林的含量

复方制剂中氨基比林与溴甲酚绿形成稳定的离于对，用氯仿萃取后在４１６．８ｎｍ处测定吸收度．回收率为９９．８０％，相对标准偏差为０．９２％（ｎ＝５）。方法简便快速，结果准确可靠。