Deficiency of a glycoprotein component of the dystrophin complex in dystrophic muscle

Dystrophin, the protein encoded by the Duchenne muscular dystrophy (DMD) gene, exists in a large oligomeric complex. We show here that four glycoproteins are integral components of the dystrophin complex and that the concentration of one of these is greatly reduced in DMD patients. Thus, the absence of dystrophin may lead to the loss of a dystrophin-associated glycoprotein, and the reduction in this glycoprotein may be one of the first stages of the molecular pathogenesis of muscular dystrophy.     

运动与骨骼肌中的基因表达

通过献资料法阐述了运动对骨骼肌基因表达的影响,以便深入理解骨骼肌的工作原理,为客观指导运动训练提供依据．     

The Duchenne muscular dystrophy gene product is localized in sarcolemma of human skeletal muscle

Duchenne muscular dystrophy (DMD) and its milder form, Becker muscular dystrophy (BMD), are allelic X-linked muscle disorders in man. The gene responsible for the disease has been cloned from knowledge of its map location at band Xp21 on the short arm of the X chromosome. The product of the DMD gene, a protein of relative molecular mass 400,000 (Mr 400K) recently named dystrophin, has been reported to co-purify with triads of mouse and rabbit skeletal muscle when assayed using polyclonal antibodies raised against fusion proteins encoded by regions of mouse DMD complementary DNA. Here we show that antibodies directed against synthetic peptides and fusion proteins derived from the N-terminal region of human DMD cDNA strongly react with an antigen present in skeletal muscle sarcolemma on cryostat sections of normal human muscle biopsies. This immunoreactivity is reduced or absent in muscle fibres from DMD patients but appears normal in muscle fibres from patients with other myopathic diseases. The same antibodies specifically react with a 400K protein in sodium dodecyl sulphate (SDS) extracts of normal human muscle subjected to Western blot analysis. We conclude that the product of the DMD gene is associated with the sarcolemma rather than with the triads and speculate that it strengthens the sarcolemma by anchoring elements of the internal cytoskeleton to the surface membrane.     

肌肉组织疲劳过程的超声衰减特征

基于超声波在生物软组织中的传播机理以及肌肉疲劳过程中组织厚度、弹性等特征的变化,研究了超声衰减特性与肌肉疲劳过程的相关性,理论分析了超声波幅度随肌肉疲劳的变化规律。设计针对右肱二头肌的实验,探讨了激励声波在逐渐疲劳的组织中传输的响应规律。同步采集表面肌电信号,研究肌肉疲劳过程中肌电信号与超声衰减特征的相关性。理论分析及实验结果表明,在肌肉疲劳过程中,随着疲劳程度的增强,超声波传输后平均能量幅度逐渐减小,其减小趋势满足指数衰减规律,同时同步采集的表面肌电信号均方根值呈线性增加趋势。     

人颞肌亚部化及其肌内神经分布研究

目的:查明人颞肌肌内神经、肌梭的配布特征以及相互关系,为临床成功进行肌移植提供解剖学依据.方法:20侧成人尸体颢肌标本,每具尸体选1侧,共10侧采用改良Sihler氏神经染色观察颞肌肌内神经分布.另10侧标本,依据颞肌肌纤维排列方向分前、中、后3部份,分别制作组织块,HE染色后应用图像分析仪对颞肌肌梭的形态结构、空间构象以及分布密度进行体视学分析.结果:改良Sihler氏神经染色显示颞肌有3条独立的神经分支呈放射状由颢肌下缘向肌远端分布.颞肌肌梭分布呈不均质性.在颞肌前部近喙突处神经分支密集区,肌梭分布密度高,空间构象多样;而在颞肌后部以及颞肌的远端缺乏肌梭的分布.结论:颞肌可划分为3个功能完整和独立的肌亚部.     

Single postsynaptic channel currents in tissue cultured muscle

Some of the most compelling evidence for the existence of ionic channels in cell membranes comes from direct recording of quantised current jumps generated by the opening and closing of individual channels. Single-channel jumps have been extensively studied for lipid bilayer membranes doped with various channel-forming additives. Recently agonist-induced single-channel currents were detected in denervated frog muscle by use of extracellular electrodes, which can isolate the current from a small area of membrane. The current jumps provide a means for the direct test of many of the inferences about ionic channels which have come from electrical noise analysis. In this report we present measurements of single-channel currents induced by the agonist carbamylcholine in tissue-cultured mammalian muscle. These measurements confirm the earlier noise studies on tissue culture preparations. Recordings of single-channel currents induced by the agonist, suberyldicholine, in avian muscle are presented by Nelson and Sachs.     

广东地区宫颈癌组织HPV18L1基因的克隆及序列分析

目的:了解广东地区地方株HFV18L1基因结构特点,为HPV感染的检测和基因工程疫苗的研制提供实验基础.方法:采用PCR技术从广东地区宫颈癌组织中扩增HPV18L1基因,克隆人毕赤酵母表达载体pPICZaB,测序并对HPV18L1基因进行序列分析.结果:广东地区分离株与德国标准株在核苷酸序列上有4处不同,其中3处由于核苷酸的改变,其编码的氨基酸也发生相应变化,与标准株的同源性为99.8%.与中国西安地区分离株比较有两处突变点相同.结论:广东地区HPV18L1分离株与德国标准株、中国其他地区分离株之间均存在差异.     

Immunoelectron microscopic localization of dystrophin in myofibres

Duchenne muscular dystrophy, a common X-linked recessive human disease, has recently been shown to be caused by the deficiency of a large, low abundance protein called 'dystrophin'. Biochemical techniques have shown dystrophin to be membrane-associated in skeletal muscle, with enrichment of dystrophin in the t-tubules of 'triads'. Other studies using immunohistochemistry on thick (10 micron) sections have shown dystrophin to be located at the periphery of muscle fibres, possibly at the plasma membrane. These results have been interpreted as being either consistent and complementary, or contradictory. To localize dystrophin more precisely relative to these membrane systems we have employed highly sensitive and spatially accurate immuno-gold electron microscopy of ultra-thin (70-100 nm) cryosections. The major distribution of dystrophin was on the cytoplasmic face of the plasma membrane of muscle fibres, and possibly on the contiguous t-tubule membranes. The presented data, taken together with recently accumulated information regarding the primary structure of dystrophin, suggests that dystrophin is a component of the membrane cytoskeleton in myogenic cells. Thus, myofibre necrosis in patients affected with Duchenne muscular dystrophy is likely the result of plasma membrane instability.     

Localization of muscle gene products in nuclear domains

The localization of gene products is central to the development of cell polarity and pattern specification during embryogenesis. To monitor the distribution of gene products encoded by different nuclei in the same cell in tissue culture, we fused cells of different species to form multinucleated non-dividing heterokaryons. In previous fusion studies, cell-surface antigens and organelles contributed by disparate cell types intermixed within minutes. Using heterokaryons produced with differentiated muscle cells, we demonstrate here that a muscle membrane component, the Golgi apparatus mediating its transport, and a sarcomeric myosin heavy chain are localized in the vicinity of the nuclei responsible for their synthesis. These results provide direct evidence that products (organelle, membrane and structural proteins) derived from individual nuclei can remain localized in myotubes, a finding with implications both for neuromuscular synapse formation and for the carrier state of Duchenne muscular dystrophy.     

慢病毒介导的HTRA1突变基因感染对人脑血管平滑肌细胞内氧化应激反应的影响

检测HTRA1及HTRA1-Mut基因慢病毒载体转染HBVSMC后,HBVSMC内氧化应激水平的变化。以HTRA1及HTRA1-Mut基因慢病毒载体转染HBVSMC后,在特定的时间点收集NC、OE-WT HTRA1及OE-MU HTRA1三组细胞的总RNA及总蛋白,分别用RT-PCR和Western Blot的方法检测三组细胞的NOX4 mRNA及蛋白水平的表达情况;用DCFH-DA法检测三组细胞内的活性氧水平。从定量PCR结果可以看出,人脑血管平滑肌细胞中,OE-MU组NOX4基因表达丰度是NC组的2.015倍。从Western blot结果可以看出,在正常的人脑血管平滑肌细胞中NOX4蛋白水平表达较低,而在慢病毒LV-HRTA1及LV-HRTA1-MUT感染后NOX4蛋白表达水平增高。在正常的人脑血管平滑肌细胞中ROS水平表达较低,而在慢病毒LVHRTA1及LV-HRTA1-MUT感染后ROS蛋白表达水平增高,在突变型病毒感染细胞组表现更为明显。说明:1HTRA1突变型基因感染人脑血管平滑肌细胞后,细胞内活性氧产量增加,NOX4 mRNA水平的表达正常细胞升高,但较HTRA1野生型基因无明显差别;NOX4在蛋白水平表达较其他两组均升高;2HTRA1突变型基因感染的人脑血管平滑肌细胞出现增殖减少、迁移活力降低以及凋亡增加可能与细胞内的氧化应激有关,为进一步研究CARASIL发病机制奠定基础。