Accentuated antagonism by angiotensin II on guinea-pig cardiac L-type Ca-currents enhanced by β-adrenergic stimulation

 To examine mechanism(s) underlying the accentuated antagonism by angiotensin II (A-II) on twitch tension, we recorded L-type Ca²⁺ currents (I _Ca,L) using conventional patch-clamp techniques in single, guinea-pig, ventricular myocytes. I _Ca,L was recorded by a step-pulse protocol after eliminating K⁺ conductances (internal Cs⁺ plus tetraethylammonium chloride and K⁺-free extracellular solution). A-II (100 nM) did not affect basal I _Ca,L, but inhibited I _Ca,L that had been enhanced (approximately 200% of control) by (ISO, isoproterenol 100 nM). The inhibitory action of A-II was concentration dependent (concentration eliciting 50% inhibition 88±9 pM, n=41) and the ISO-enhanced component of I _Ca,L was completely blocked by A-II at concentrations above 10 nM. CV-11974 (500 nM), an A-II type-1 receptor (AT₁) antagonist, prevented the inhibitory action of A-II. Pre-incubation with pertussis toxin (PTX) abolished the inhibitory effect of A-II. A-II also inhibited the I _Ca,L enhanced by histamine (500 nM) and forskolin (1 μM), but failed to affect I _Ca,L enhanced by intracellular cyclic adenosine monophosphate (1 mM). The inhibitory action of A-II may therefore involve AT₁ receptors/PTX-sensitive, guanine nucleotide-binding (G) proteins (Gi)/adenylate cyclase and partially explains the A-II-dependent accentuated antagonism of inotropy.     

锌及复合微量营养素的营养干预对学龄前儿童蛋白质营养状况的影响

选择重庆市近郊农村学龄前儿童１４０名，男、女各半，随机分为单纯补锌组、补锌及复合微量营养素组和单纯补充微量营养素组，另一组为对照。实验组每组４０人，对照组为２０人，进行１０周营养干预实验。结果显示，在补锌的同时服用硒、锰、维生素Ａ等多种微量营养素或单纯补充多种微量营养素均能有效改善受试儿童体内锌营养状况，使血浆中前白蛋白、转铁蛋白、铜蓝蛋白含量增加，血清中多种必需及非必需氨基酸，３甲基组氨酸浓度下降。提示，儿童营养状况改善后其体内蛋白质合成代谢加强，而分解减少，这种变化除缘于血清锌含量增加外，可能还与其它微量营养素的作用有关。而单纯补锌儿童血清锌变化并不显著，血清中几种转运蛋白与对照均无明显差异。     

振动对急性缺氧小鼠肺损伤的影响

本文观察了频率为20Hz、振幅为0．67mm和作用时间为40min的振动预处理对急性缺氧小鼠肺损伤的影响。结果发现实验组的肺组织匀浆脂质过氧化物LghdPeroxde（LPO）、支气管肺泡灌洗液（BALF）中蛋白含量和白细胞数明显低于对照组（P＜0．05）。这表明在特定率数的振动作用下能明显减轻急性缺氧小鼠肺的损伤。     

非创伤性股骨头坏死患者的血液学改变

目的测定非创伤性股骨头坏死(nontraumaticosteonecrosisoffemoralhead,NONFH)患者的血液学指标变化,筛选敏感分子标记物用于早期诊断和筛选高危人群。方法研究对象共分三组:(1)NONFH早期组(塌陷前期)30例,(2)NONFH晚期组(塌陷后期)30例,(3)正常对照组30例。各组对象均抽取空腹肘静脉血。应用酶联免疫吸附法(ELISA)测定血小板α-颗粒膜蛋白(GMP-140)、血浆蛋白C(PC)、D-二聚体(D-Dimer)含量;发色底物法测定血浆纤溶酶原激活剂抑制剂(PAI)活性。结果(1)NONFH早、晚期组血小板GMP-140含量均高于正常对照组,血浆PC含量均低于正常对照组,D-Dimer含量均高于正常对照组,PAI活性均高于正常对照组(P均<0.05)。骨坏死情况越严重,各项指标上升或降低的趋势越明显,而且各项指标早、晚期组间比较差异均有显著性(P均<0.05)。(2)经判别分析,筛选出PAI、D-Dimer、PC三个指标,建立NONFH早期、晚期和正常对照三类判别函数式。NONFH早期:Y1=?26.3966 41.4916X10 0.0512X4 4.1390X1;NONFH晚期:Y2=?66.7566 82.1315X10 0.1082X4 2.7233X1;正常对照组:Y3=?26.7049 20.5695X10 0.0327X4 6.1900X1。回代判对率97.78%。结论(1)NONFH患者各期均存在高凝和低纤溶状态。(2)PAI、D-Dimer、PC为NONFH患者的血液学敏感指标。     

Chronic lithium treatment increases the phosphorylation of a 64-kDa protein in rat brains

Despite the wide clinical use of lithium in the treatment of manic depressive illness there is no adequate explanation for its mechanism of action. In the light of lithium's suggestive effects on the second messenger system in the brain, we studied the effects of chronic dietary lithium treatment (achieving blood levels in the therapeutic range) on protein phosphorylation in different areas of rat brain. An increase in the phosphorylation of a 64-kDa membrane-associated protein was evident in the lithium-treated rats compared to controls. This increase was observed only under basal phosphorylating conditions and was abolished when the phosphorylation was performed in the presence of Ca²⁺ or Ca²⁺ and calmodulin. The possibility that this 64-kDa protein affected by lithium is the beta-subunit of the calmodulin-dependent protein kinase or a different protein which co-migrates with it is discussed.     

Ethanol-Induced Enhancement of Cocaine Bioactivation and Irreversible Protein Binding: Evidence Against a Role of Cytochrome P-450IIE1

Chronic ethanol consumption potentiates cocaine-induced liver injury in rodents. Since cocaine has to be bioactivated by a cytochrome P-450-dependent N-oxidative pathway to exert its hepatotoxic effects, we studied the role of the ethanol-inducible P-450IIE1 for cocaine metabolism. Male Sprague-Dawley rats were pretreated with either a liquid diet containing ethanol (30% of calories) for 4 weeks or injected with pyrazole (200 mg/kg/day, ip, for 3 days). Both agents induced microsomal p-nitrophenol hydroxylation which is a probe for the catalytic activity of P-450IIE1. However, only ethanol, but not pyrazole, increased both microsomal cocaine N-demethylase activity (by 47%) and the extent of irreversible binding of [3H]-cocaine to microsomal proteins (by 100%), which was taken as a quantitative endpoint for the formation of a reactive metabolite. Cocaine N-demethylation and irreversible protein binding of cocaine were not inhibited by P-450IIE1 isozyme-selective substrates, nor was the rate of cocaine metabolism and binding decreased by functionally active polyclonal anti-rat P-450IIE1 antibodies. Furthermore, pyrazole pretreatment sensitized cultured hepatocytes to the glutathione-dependent cytotoxic effects of nontoxic concentrations of cocaine. These results indicate that (a) cocaine is not a major substrate for the ethanol-inducible P-450IIE1, (b) the enhancing effects of ethanol on cocaine bioactivation may be due to induction of other P-450 isoforms, and (c) induction of P-450IIE1 may potentiate cocaine-induced hepatocellular toxicity in vitro independently of cocaine metabolism, e.g., by P-450IIE1-dependent oxidative stress.     

蛋白芯片检测系统(多肿瘤标志物C12系统)的应用评价

目的：应用并评价蛋白芯片检测系统(多肿瘤标志物C12)的临床价值。方法：应用雅培电化学发光系统(ECL)和C12系统双盲法检测41份血清标本。结果：在对照检测达10份标本的AFP、CEA、β-HCG三个项目，C12系统和ECL系统符合性达81．8％以上；C12系统多个指标间可相互支持其准确性，并有助于判断肿瘤来源。结论：C12系统具有较高准确性，其指标间可相互支持，并有助于判断肿瘤源性。     

人T淋巴母细胞（Jurkat）移动性的研究

利用人Ｔ淋巴母细胞（Ｊｕｒｋａｔ）细胞系作为研究对象。企图探探索细胞外基质成份及肌醇磷脂细胞信息传递系统与细胞移动的关系。研究结果表明：当细胞被伏波醇酯（ＰＭＡ）处理过后，其粘连性与移动件对纤维连结蛋白（ＦＮ）底物的反应在已是高水平的基础上有更进一步提高的作用。与ＦＮ刊相反的是，未经ＰＭＡ处理处的Ｊｕｒｋａｔ细胞对层粘连蛋白（Ｌｍ）底物却无明显的粘连性及移动性增加的反应，尽管在ＰＭＡ处理过４小时内亦无任何的增强。但是，当ＰＭＡ作用于细胞２４一４８小时后则明显池增加其Ｌｍ底物的粘连性及移动性反应，表明了其明显的协同作用。分别用抗ＦＮ、抗Ｌｍ及蛋白激酶Ｃ抑制剂Ｓｔａｕｒｏｓｐｒｉｎｅ（ＳＰ）时均起到特异性的抑制作用。可见，协同作用的产生是通过蛋白激酶Ｃ激活后的－段时间内，使细胞表面Ｌｍ受体密度增加而对底物Ｌｍ反应增强所致。     

p38丝裂原活化蛋白激酶在糖尿病大鼠神经病理性痛中的作用

目的探讨p38丝裂原活化蛋白激酶（p38MAPK）在链脲菌素诱导的糖尿病大鼠神经病理性痛中的作用。方法雌性Wistar大鼠31只，3月龄，体重180～220g，随机分为3组：对照组（C组，n=10）、糖尿病神经病理性痛组（D组，n=11）和p38MAPK抑制剂组（Ⅰ组，n=10）。D组、Ⅰ组单次腹腔注射链脲菌素65mg／kg制备糖尿病模型。糖尿病模型制备成功后，Ⅰ组尾静脉注射p38MAPK抑制剂SB203580 0．5mg／kg，1次／周，连续4周；C组和D组尾静脉注射等体积的生理盐水。给药4周后，测定机械缩足反应阈值（MWT）、左侧坐骨神经传导速率（NCV）、背根神经节（DRG）和脊髓的磷酸化p38MAPK水平。结果与C组比较，D组、Ⅰ组MWT下降，NCV减慢，伴有脱髓鞘现象，DRG和脊髓的磷酸化p38MAPK水平升高；与D组比较，Ⅰ组MWT升高，NCV增快，脱髓鞘程度减轻，DRG和脊髓的磷酸化p38MAPK水平下降。结论p38MAPK信号转导通路参与了糖尿病大鼠神经病理性痛的形成。     

膳食纤维与不同蛋白质联用对大鼠胆固醇代谢的影响

观察４种膳食纤维在两种蛋白来源下，对高脂血症大鼠生长、血脂、肝胆固醇、粪类固醇及胆汁成分的影响。结果表明：①四种膳食纤维均可降低大鼠血清ＴＣ水平，尤以豆胶效果显著。②豆胶显著升高ＨＤＬ－Ｃ／ＬＤＬ－Ｃ。膳食蛋白为大豆蛋白时，豆胶、沙棘皮可显著升高血清ＨＤＬ－Ｃ、ＨＤＬ－Ｃ／ＴＣ。③豆胶显著减少肝胆固醇累积，两种沙棘皮与大豆蛋白联用降脂强于与酪蛋白共用。④蛋白来源显著影响粪类固醇的排出，纤维类型可影响中性固醇排出并与蛋白质有交互作用。提示：蛋白质与膳食纤维之间的交互作用是探讨营养素与脂质代谢不可忽视的因素。