不同频率电刺激膈神经导致膈肌肌浆网Ca~(2 )-ATPase和Ca~(2 )释放-摄取动力学改变

研究不同频率慢性电刺激（ＣＥＳ）后兔膈肌肌浆网（ＳＲ）Ｃａ２＋－ＡＴＰａｓｅ活性以及ＳＲ Ｃａ２＋摄取－释放动力学对不同频率ＣＥＳ的适应性变化。建立不同频率ＣＥＳ组;用定磷法测定ＳＲ Ｃａ２＋－ＡＴＰａｓｅ活性;用Ｆｕｒａ－２荧光法测定ＳＲ　Ｃａ２＋摄取－释放动力学。与对照组比较,慢性低频电刺激１０ Ｈｚ和２０Ｈｚ组的ＳＲ　Ｃａ２＋－ＡＴＰａｓｅ活性明显降低（Ｐ＜０．０１）,Ｃａ２＋释放－摄取动力学也显著降低（Ｐ＜０．０１）;慢性高频电刺激５０ Ｈｚ和１００Ｈｚ组的ＳＲ Ｃａ２＋－ＡＴＰａｓｅ活性则显著升高（Ｐ＜０．０１）,Ｃａ２＋释放－摄取动力学亦明显升高（Ｐ＜０．０１）。实验提示,ＣＥＳ后不同频率ＣＥＳ导致膈肌ＳＲＣａ２＋－ＡＴＰａｓｅ、Ｃａ２＋摄取－释放动力学产生不同的适应性变化;对不同功能状态的膈肌应用不同频谱的慢性电刺激可能具有重要的临床意义。     

失血性休克引起大鼠肠系膜动脉平滑肌依钙K~ 通道活动改变

在由股动脉放血制备的失血性休克大鼠模型急性分离的肠系膜动脉平滑肌细胞上 ,利用膜片箝单通道记录技术观察了血管平滑肌依钙K 通道 (BKCa)的活动。发现在对去甲肾上腺素 (NE)反应性增高的休克代偿期 ,BKCa的开放概率 (Po)和单位电导都显著较正常动物的低 ,Po 的改变主要是由通道的慢关闭时间常数 (τcs)增大引起关闭时间延长所致 ;而处于对NE反应性降低的休克失代偿期 ,BKCa的Po 和单位电导都高于正常动物 ,Po的变化也主要是τcs减小所致。     

人细胞骨架调节蛋白基因NELIN cDNA的克隆及特征分析

为寻找和研究心血管系统有关的重要功能基因及表达模式,构建了正常成人心脏和主动脉cDNA文库,并在大规模表达序列标签（ESTs）测定和筛选新的cDNAs全长的基础上,筛选出一个新的基因（GenBank登记号AF114264）。该基因的cDNA全长为2736bp,含有一个1344bp的开放读码框,由于其推测的氨基酸序列与鼠源微管连接蛋白（nexilin）具有很高同源性,所以暂将其命名为NELIN（nexilin-like protein)。Northern印迹和RT－PCR结果表明,该基因的心脏、骨骼肌、动脉和静脉中表达,且该表达有一定的时空特异性,查询GeneMap‘99,该基因定位在梁色体1p31－1p32。结构域分析表明,NELIN很可能参与调节粘着斑和张力纤维形成,并参与粘着斑的信号转导。     

Effects of prepubertal castration on the spinal motor nucleus of the ischiocavernosus muscle of the rat

Summary The location, number and size of the motoneurons innervating the ischiocavernosus muscle, identified by means of horseradish-peroxidase (HRP) retrograde transport, were studied (1) in adult untreated male rats, (2) in adult male rats castrated before puberty, and (3) in adult male rats castrated before puberty and injected with testosterone from the day of castration. After injection of HRP into the ischiocavernosus muscle, labeled motoneurons were found in the dorsolateral and dorsomedial columns of the lamina IX, at the level of L6 and S1 segments of the spinal cord. Morphometric analysis demonstrated that prepubertal castration induces a statistically significant reduction in the somatic and nuclear areas (40% and 35%, respectively, if compared to those of the control rats) of both the dorsolateral and dorsomedial motoneurons, but does not affect their number. The effects of castration are prevented by exogenous testosterone.Preliminary results were presented at the International Conference on Hormones, Brain and Behaviour, Liège, Belgium, August, 1989     

Modulation of haloperidol induced electrophysiological alterations on cardiac action potential by various risk factors and gender difference

Haloperidol (HPL), well known antipsychotic drug can induce a marked QT prolongation and polymorphic arrhythmias. In this study we evaluated the influence of various induced risk factors such as electrolyte imbalance (hypokalemia and hypomagnesemia), gender difference, low pacing frequency, ischemia reperfusion insult on electrophysiological effect by haloperidol on electrically driven action potentials recorded from guinea pig papillary muscle. The doses of HPL ranging from 1 to 16 μM were used in this investigation. Action potentials (APs) were elicited electrically and recorded by classical microelectrode technique. HPL caused dose dependent prolongation of APD₉₀ the final stage of repolarization, increased triangulation, and led into dispersion of action potential, conduction delay and conduction block. Magnitude of the effect of haloperidol was amplified significantly by most of the risk factors. Among the various risk factors, electrolyte imbalance (hypokalemia, hypomagnesemia) caused more amplification of HPL effect. Most of the risk factors amplified prolongation of APD₉₀ by HPL. This effect is mainly due to the influence of these electrolytes and sex hormone on various ion channels involved in the repolarization phase of cardiac AP. This is the first report which provides an experimental evidence of amplification of electrophysiological effects of HPL in the presence of various risk factors.     

High-Resolution Cryo-EM Structure of the Cardiac Actomyosin Complex

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Non‐muscle myosin IIB helps mediate TNF cell death signaling independent of actomyosin contractility (AMC)

Non‐muscle myosin II (NM II) helps mediate survival and apoptosis in response to TNF‐alpha (TNF), however, NM II's mechanism of action in these processes is not fully understood. NM II isoforms are involved in a variety of cellular processes and differences in their enzyme kinetics, localization, and activation allow NM II isoforms to have distinct functions within the same cell. The present study focused on isoform specific functions of NM IIA and IIB in mediating TNF induced apoptosis. Results show that siRNA knockdown of NM IIB, but not NM IIA, impaired caspase cleavage and nuclear condensation in response to TNF. NM II's function in promoting cell death signaling appears to be independent of actomyosin contractility (AMC) since treatment of cells with blebbistatin or cytochalasin D failed to inhibit TNF induced caspase cleavage. Immunoprecipitation studies revealed associations of NM IIB with clathrin, FADD, and caspase 8 in response to TNF suggesting a role for NM IIB in TNFR1 endocytosis and the formation of the death inducing signaling complex (DISC). These findings suggest that NM IIB promotes TNF cell death signaling in a manner independent of its force generating property. J. Cell. Biochem. 9999: 1365–1375, 2010. © 2010 Wiley‐Liss, Inc.     

Development of the hand and wrist bones in chimpanzees

Skeletal developmental of chimpanzees was studied cross-sectionally. By application of the TW2 method, we described the skeletal development of chimpanzees and compared their skeletal development with humans'. A development pattern of chimpanzees repeated accelerations and decelerations displaying “early-juvenile trough,” “pre-adolescent peak,” “mid-adolescent trough,” and “post-adolescent peak” in incremental curves. Sex differences in skeletal development are slower development in males during infant and early juvenile phases, and greater increment around the adolescent phase in males. Females are fully mature at younger ages than males, e.g. about one and a half years. In comparison with chimpanzees, humans have such characteristics as a longer slower period of juvenile development and a shorter spurt-like adolescent fast period which ends with full maturity.     

C-Met expression and mechanical activation of satellite cells on cultured muscle fibers.

Single-fiber cultures can be used to model satellite cell activation in vivo. Although technical deficiencies previously prevented study of stretch-induced events, here we describe a method developed to study satellite cell gene expression by in situ hybridization (ISH) using protocol modifications for fiber adhesion and fixation. The hypothesis that mechanical stretching activates satellite cells was tested. Fiber cultures were established from normal flexor digitorum brevis muscles and plated on FlexCell dishes with a layer of Vitrogen. After 2 hr of stretch in the presence of BrdU, satellite cells on fibers attached to Vitrogen were activated above control levels. In the absence of activating treatments or mechanical stretch, ISH studies showed 0-6 c-Met+ satellite cells per fiber. Time course experiments demonstrated stable quiescence in the absence of stretch and significant peaks in activation after 30 min and 2 hr of stretch. Frequency distributions for unstretched fiber cultures showed a significantly greater number of quiescent c-Met+ satellite cells than were activated by stretching, suggesting that typical activation stimuli did not trigger cycling in the entire c-Met+ population of satellite cells. These methods have a strong potential to further dissect the nature of stretch-induced activation and gene expression among characterized populations of individual quiescent and activated satellite cells.     

Structure and function of muscle myosin

We have studied the primary structures of myosins from chicken muscles in order to clarify the relationship between structure and function of muscle myosin. The primary structures of the various kinds of light chains from chicken muscle myosins have been determined. We also report the primary structure of the 23K fragment of subfragment-1 (S-1) component from the heavy chain of chicken fast skeletal muscle myosin. In addition, antibody was prepared against the 23K fragment. The antibody was found to inhibit the Mg²⁺-ATPase activity and the initial P_i burst of the ATPase in the S-1 component. The antibody suppressed the ATP-induced fluorescence enhancement of S-1, though it did not suppress the binding of ATP to S-1. These results are also discussed.This article was presented during the proceedings of the International Conference on Macromolecular Structure and Function, held at the National Defence Medical College, Tokorozawa, Japan, December 1985.