骨骼肌兴奋收缩偶联时肌浆网膜Ca2+通道的研究

目的：从毫秒级功能变化水平实时观察骨骼肌肌浆网、T-管在收缩潜伏期内超微结构的时相—形态变化。方法：采用双红外线探测器—计算机控制的电刺激—超低温快速冷冻固定同步技术,对电刺激后的蟾蜍骨骼肌组织作快速冷冻固定,采用透射电镜对骨骼肌在电刺激后0．8ms,2ms,4．6ms,10．8ms和18．4ms的超微结构变化进行观察。结果：刺激0．8ms后,肌浆网和T-管未见明显改变。刺激2ms后,SR内出现电子密度较大的物质。刺激4．6ms后,肌浆网膜内外侧可见一一对应的电子密度大的物质。刺激10．8ms后,SR与T-管形态又恢复原状,SR内电子密度大的物质消失。结论：骨骼肌兴奋-收缩偶联发生时,肌浆网的形态发生改变,肌浆网内出现电子密度较大的物质且逐渐向靠近T-管的方向移动。     

骨骼肌兴奋收缩偶联时肌浆网内Ca2+释放的形态-功能变化研究

采用双向红外线探测器－计算机控制的电刺激－超低温快速冷冻固定同步技术,透射电子显微镜,X－射线能量色散谱及Ca^2 细胞化学技术,从超微结构形态学角度,实时研究并获取骨骼肌兴历－收缩偶联时,肌浆网内Ca^2 释放及肌浆网的形态改变。研究表明：1．骨骼肌组织在收缩潜伏期内,肌浆网膜与T－管膜接触。2．在潜伏期（＜10ms)内,肌浆网内的钙离浓度随时间经历的延长而减少。3．骨骼肌组织在收缩潜伏期开始0．8ms时,在T－管外周围（纳米处）,有Ca2 分 ,丰,可以认为骨骼肌兴奋收缩偶联时,T－管外存在Ca^2 结合位点。     

计算机控制的电刺激-超低温快速冷冻固定同步的研究

本文报道了以红外线技术和计算机控制的电刺激 -超低温快速冷冻固定同步技术 ,研究骨骼肌组织被电刺激后 ,与骨骼肌组织的生理变化 (即兴奋 -收缩偶联发生的瞬间 )同步 ,在骨骼肌组织结构发生变化的同时 ,对其超低温快速冷冻固定 ,从毫秒级变化的水平获得骨骼肌组织在兴奋-收缩偶联发生时的细胞超微结构形态变化。材料与方法　双向红外探测器由两对透射型红外光电开关管及相应的信号处理及脉冲整形输出线路构成。透射型红外光电开关管的响应时间小于 1 0 μs,可满足毫秒级分析要求。脉冲整形输出线路将透射型红外光电开关管接收的信号转换成…     

骨骼肌在兴奋收缩偶联潜伏期内毫秒级功能变化时的形态研究

骨骼肌在兴奋收缩偶联潜伏期内毫秒级功能变化时的形态研究杨勇骥郑尊邵晓良夏金辉余宏宇姜永良宋田斌吴越（第二军医大学基础部生物物理研究所，上海２００４３３）采用双向红外线探测器—计算机控制的电刺激与超低温快速冷冻固定同步技术对骨骼肌组织电刺激后，在潜伏期...     

骨骼肌收缩潜伏期内肌浆网Ca2+的定量定位研究

本文报道了采用红外探测-计算机控制的超低温快速冷冻固定技术、X-射线能量色散谱微区定量分析及Ca2+细胞化学技术对骨骼肌收缩潜伏期内肌浆网内的Ca2+进行了分析,从超微结构形态学的角度对骨骼肌兴奋-收缩偶联发生时,Ca2+的作用进行了研究,这对揭示骨骼肌兴奋-收缩偶联时,肌浆网内Ca2+的释放机理研究有重要意义.     

骨骼肌毫秒级功能变化时的结构研究

本文报道了采用两对透射型红外传感器及数字脉冲输出电路组成的双向红外线探测器,与计算机连接,以自研的软件控制超低温快速冷冻固定仪,从超微结构的水平研究生物组织、细胞在毫秒级功能变化时的同步形态变化,并获得骨骼肌在兴奋－收缩偶联发生瞬间的肌细胞超微结构变化     

骨骼肌间质中含铁小体细胞两例电镜观察

含铁小体 ( siderosome)是由单层界膜包绕的内含大量含铁颗粒的残余小体。正常网状内皮系统的细胞中有少量的含铁小体。在疾病或实验条件下 ,如出血、注射铁剂等等情况下 ,含铁小体可以大量出现在病灶或实验对象相应器官附近的巨噬细胞或其他细胞中。我们在研究骨骼肌的形态过程中 ,发现在两例不同骨骼肌样品的间质中 ,存在着含铁颗粒细胞 ,现报道如下。资料、方法与结果例一 :正常蟾蜍缝匠肌 ,经常规电镜制样后 ,在进行超微结构观察时偶然发现 ,在间质中有一异常死亡细胞 (图 1 ) ,但附近骨骼肌组织结构正常。该细胞呈椭圆形 ,细胞核固缩 ,…     

骨骼肌兴奋收缩偶联时钙诱导钙释放机理的研究

近年来 ,国外学者由生理学实验发现 ,在骨骼肌兴奋 -收缩偶联过程中 ,不仅存在 DCT假说 ,还存在钙诱导钙释放 ( Calcium Induced Calcium Release,简称 CICR)假说 (该假说一般用于解释心肌兴奋 -收缩偶联时 ,肌浆网内的 Ca2 + 释放机理 )。但因肌组织 (包括骨骼肌与心肌 )兴奋 -收缩偶联发生时的变化时间极快 ,达到毫秒级水平 ,因此目前常规化学固定 (固定时间以分钟计 )制样法无法保留肌组织兴奋 -收缩偶联发生瞬间时的超微结构形态及离子 (包括 Ca2 + ,Na+ ,K+ 等 )浓度的变化。我们采用双向红外线探测器 -计算机控制的电刺激与超低…     

生物样品的冷冻超薄切片术

当生物材料在样品制备过程中需减少化学固定剂对样品中蛋白活性的影响或减少可溶性元素流失时,可采用快速冷冻固定法和冷冻超薄切片。切片在含水状态下或经冷冻干燥后,用电镜观察,这样既能显示生物细胞在体内的形态,又使细胞内各种活性得以保存,是一种值得推广的电镜技术。我们采用新鲜活组织快速冷冻固定和冷冻超薄切片,经冷冻干燥后在透射电镜下对亚细胞结构进行形态观察和微小区域内的元素定性、定量分析,本文总结了初步结果和经验。     

高压冷冻技术在拟南芥细胞微结构研究中的应用

高压冷冻技术是指以高压冷冻固定为主要内容的一种电镜技术。该技术可以充分、快速固定样品的同时,避免引入操作干扰,使得电镜结构更接近样品生活状态。本文利用拟南芥为材料,比较了高压冷冻固定及冷冻替代制备的电镜样品同常规化学固定、室温梯度脱水方法所制备样品的差异。结果显示,在拟南芥根及叶片中,高压冷冻技术可以有效地避免常规制备样品中的细胞壁收缩,细胞质不均匀分布,高尔基体及质体收缩,细胞膜及液泡膜皱缩甚至断裂等现象,使细胞结构更接近其生活时的状态。     

Tetanic responses of electrically stimulated paralyzed muscle atvarying interpulse intervals

The influence of stimulus interpulse interval (IPI) on torque output during electrically-evoked contractions was investigated for the knee extensor muscles of paralyzed subjects. The parameters measured were the rise time, magnitude, and relaxation time of the contraction at stimulus IPI's ranging from 62 to 7 ms. Torque output increased as IPI's were decreased from 62 to 15 ms. Peak torques were recorded at IPI's of 12-15 ms; IPI's less than these resulted in an insignificant loss of torque. Rise times decreased as IPI's were decreased. Relaxation time generally increased as IPI's were decreased with the longest relaxation times occurring with stimulation at an IPI of 12 ms. To demonstrate the influence of IPI on muscle fatigue, the effect of prolonged stimulation at short (12 ms) and long (50 ms) IPI's was also compared. After 30 s of stimulation with an IPI of 12 ms, mean torque had declined to 5 +/- 3 percent and after 30 s of stimulation with an IPI of 50 ms, mean torque had declined to 82 +/- 4 percent of the initial value. Knowledge of how stimulus IPI influences the response of paralyzed muscle to electrical stimulation may assist in the development of rehabilitation devices which utilize these technologies.     

The dynamic response model of nine different skeletal muscles

The frequency response model of nine different skeletal muscles in the hindlimb of the cat was determined with the aide of electrical nerve stimulation which allows orderly stimulation of motor units concurrently with firing rate increase. It was shown that the general model consists of a linear second-order system with double real poles and a pure time delay. The pole values were different for the different muscles, ranging from 1.55 to 2.8 Hz. Similarly, the pure time delay varied from muscle to muscle, ranging from 8 to 17 ms. Statistical analysis demonstrates that under isometric contraction with force oscillations in the range of 10-90% of maximal the model poles are determined, and could be predicted, from the muscles functional and anatomical location in the limb and from its pennation pattern.     

电刺激—冷冻固定法研究兴奋收缩偶联时骨骼肌的超微结构形态变化

兴奋－收缩偶联时，肌浆网中的钙离子是通过何种途径被刺激而释放的？偶联发生时期形态变化与其功能变化存在着什么的关系？这是细胞生物学、生理学几十年来最感兴趣的研究热点之一。     

Reducing muscle fatigue in FES applications by stimulating withN-let pulse trains

Applications of electrical stimulation for restoration of functional movements such as standing, gait, and grasp have always been hindered by the rapid fatigue of stimulated muscle. This paper describes an experimental investigation of stimulation with N-lets (a set of N closely spaced stimulation pulses) as a means of producing contractions with improved fatigue characteristics. Experiments were conducted on 27 able-bodied and four SCI human subjects using surface stimulation of the quadriceps muscle to produce isometric knee joint torque. Based upon evidence from the literature on muscle fatigue, parameters of the N-let trains for N=1-6 were optimized to produce the most force per pulse. The results demonstrated that: 1) nonlinear summation of the twitch response occurs in human subjects with N-let surface stimulation; 2) for most subjects, doublet stimulation (N=2) with a pulse interval of about 5 ms produced the maximum torque-time integral per pulse of the resulting twitch; and 3) on average, optimal N-let stimulation resulted in a 36% increase in isometric torque tracking when compared to traditional singlet stimulation. The results have immediate implications for alleviating the problem of premature fatigue during functional electrical stimulation     

A Bioprinting Process Supplemented with In Situ Electrical Stimulation Directly Induces Significant Myotube Formation and Myogenesis

Electric field stimulation has supported biophysical and biological cues for tissue regeneration approaches to affect cell morphology, alignment, and even cellular phenotypes types. Here, an innovative bioprinting approach supported by in situ electrical stiumlation (E-printing) is used to fabricate a bioengineered skeletal muscle construct composed of human adipose stem cells and methacrylated decellularized extracellular matrix (dECM-Ma) derived from porcine muscle. To obtain highly ordered myofiber-like structures, various parameters of the printing process are optimized. The E-printed structure exhibits higher cell viability and fully aligned cytoskeleton than the conventionally printed cell-bearing structures, due to activation of voltage-gated ion channels that affect various signaling pathways. When using the E-printed structure, expression of myogenesis-related genes is upregulated by 1.9–2.5-fold higher than when using a dECM-Ma structure produced without electrical stimulation. Furthermore, when implanted into a rat model of volumetric muscle loss, the structure yields outstanding myogenesis relative to the conventionally bioprinted structure.     

A musculotendon model of the fatigue profiles of paralyzedquadriceps muscle under FES

A musculotendon model of the quadriceps muscle of the activated leg of a paraplegic patient incorporating fatigue was developed. The right quadriceps of a paraplegic patient who was engaged in a functional electrical stimulation (FES) training program was used for the measurements. The muscle studied was considered trained, both relating to strength and fatigue resistance. Extended stimulation was applied with an adjustable electrical stimulator, providing monophasic rectangular pulse trains with a frequency of 20 Hz, pulse width of 0.2 ms, and an intensity of up to 220 mA. The intensity used corresponded to the intensity required for the tested patient to stand up. This intensity was selected to deliberately encourage fatigue, and the result was a gradual and steady decay of the muscle force due to fatigue. The model was able to predict the decaying force during continuous electrical stimulation, as well as to indicate the muscle parameters which yield the best fit between the model prediction and the previously obtained experimental force profiles     

患者增殖体、扁桃体组织内尼曼-匹克细胞的超微结构观察

目的：观察尼曼-匹克病患者增殖体、扁桃体组织中的尼曼-克细胞的超微结构。方法：取增殖体、扁桃体组织做超薄切片,透射电镜下观察尼曼-匹克细胞的超微结构。结果：在透射电镜下,尼曼-匹克细胞呈圆形或椭圆形,细胞质丰富,其中有数量不等的嗜锇板层小体,呈板层状或同心圆状排列。细胞基底部,可查见单层或多层基底膜和细胞表膜下有少数吞饮小泡,具有内皮细胞形态特征。结论：尼曼-匹克细胞的细胞质内可见数量不等的嗜锇板层小体及基底部的单层或多层基底膜,为其特征性的结构,可作为电镜超微结构诊断及鉴别诊断的形态学依据。     

Suppression of stimulation artifacts from myoelectric-evokedpotential recordings

A system that allows detection of single and double differential surface myoelectric signals during electrical stimulation of either the nerve or the muscle motor point, using surface electrodes, is described. The input referred stimulation artifact is limited to less than 24 μV _pp by a switching constant current/constant voltage output stage, slew rate limiting, and time windowing of the detected signal. The system is suitable for muscle crosstalk and for muscle fatigue investigation during functional electrical stimulation, in addition to measuring muscle or nerve conduction velocity