首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Nerve Stump Length and Membrane Changes in Denervated Skeletal Muscle   总被引:5,自引:0,他引:5  
THE effect of nerve stump length on the rate of failure of neuromuscular transmission and on the degeneration of the neuromuscular apparatus has been studied in some detail1–4 and there is general agreement that neuromuscular transmission fails and the nerve terminals degenerate more rapidly if the nerve is cut close to the muscle than if it is cut far away.  相似文献   

2.
当今骨科领域,周围神经损伤一直影响着患者疗效。肌萎缩的发生,细胞凋亡导致骨骼肌萎缩,神经-肌肉接头处营养因子的代谢发生障碍,肌卫星细胞的减少,生长因子以及线粒体和各种酶的变化都是失神经骨骼肌萎缩的机制。电刺激法,保护神经元,生长因子,神经植入提高神经再生速度以及被动活动可以有效治疗患者。失神经骨骼肌萎缩的研究进展也趋于完善。  相似文献   

3.
This technique has been developed especially to stain sensory receptors which have been localised intramuscularly by electrophysiological means. Rat intertransverse caudal muscles, removed immediately after death, are fixed for 24 hr in a freshly prepared mixture of absolute ethyl alcohol, 4.5 ml; distilled water, 5 ml; and concentrated HNOa, 0.1 ml. After a further 24 hr in 10 ml of absolute ethyl alcohol containing 0.1 ml of ammonia solution (sp. gr. 0.88), the muscles are washed in distilled water for 30 min and placed in full strength pyridine for 2 days. They are then washed for 24 hr in distilled water (changed 5-8 times) and left in 2% AgNO3, in the dark for 3 days at 25 C. Following reduction in 10 ml of 5% formic acid containing 0.4 gm of pyrogallol for 6-24 hr, the specimens are washed briefly in distilled water and stored in pure glycerol. The nerve endings can then be teased out and mounted in glycerol, under cover glasses ringed with a waterproof cement. The advantage of this method is that it gives consistently good staining of receptors and motor end-plates in small muscles of the rat  相似文献   

4.
1. An extract of denervated skeletal muscle contained activity for promotion of neurite outgrowth from telencephalic neurons, as well as that from neurons in the spinal cord. A factor responsible for the activity was characterized in cultures of dissociated neurons.2. The factor acted on neurons only when they were attached to the surface of culture dishes. Since treatments with proteases and lectins reduced the outgrowth-promoting activity, the factor was thought to be a glycoprotein.3. Among the monoclonal antibodies raised against the partially purified extract, five antibodies were found to inhibit the activity for spinal and telencephalic neurons. The most potent antibody, 4D2a, recognized mainly a 63-kD protein and other minor proteins in the extract. Although the 63-kD protein was confirmed to be chick serum albumin by analysis of amino acid sequence, the purified albumin exhibited no activity.4. From these observations, the factor was found to be a glycoprotein recognized by the neutralizing antibody as one of the minor components of the extract. This factor exhibits its activity in a substrate-bound form but not in a diffusible one.  相似文献   

5.
目的探讨大鼠肌卫星细胞移植能否延缓失神经骨骼肌萎缩。方法将16只成年Wistar大鼠分为实验组与对照组,两组均切断大鼠右后肢胫神经,建立腓肠肌失神经动物模型。实验组:将体外培养的同种异体肌卫星细胞悬液0.2mL缓慢注射到失神经腓肠肌内、外侧头中;对照组:则缓慢注射等量的生理盐水于相同部位。术后第4周,采用肌湿重、肌纤维横截面积形态学观测的方法,检测失神经骨骼肌的萎缩变化情况。结果成功地对成年大鼠肌卫星细胞进行了分离、纯化、鉴定、培养和移植。发现实验组与对照组相比,失神经腓肠肌湿重残存率(由手术侧与自身健侧的肌湿重测定值之比得出):实验组为0.48±0.050,对照组为0.33±0.059,二者存在显著性差异(P〈0.01);腓肠肌纤维横截面积残存率(由手术侧与自身健侧的肌纤维横截面积测定值之比得出):实验组为0.58±0.011,对照组为0.50±0.018,二者存在显著性差异(P〈0.01)。结论本实验表明将肌卫星细胞异体移植到失神经骨骼肌内可明显延缓骨骼肌的萎缩进程,为再生神经到达靶器官提供较多的时间,进而为解决再生神经延伸到靶器官前,靶器官已发生不可逆性萎缩,严重制约再生神经效果的临床难题提供一个新的研究思路。  相似文献   

6.
Skeletal muscle, teased into strips several millimeters long and 1 mm or less thick, is fixed in a 3:1 mixture of lemon juice and formic acid until transparent. The tissue is compressed between folds of absorbent material to remove excess fixative and impregnated for 10 min in a volume of 1% gold chloride equal to the volume of muscle. After removing excess gold chloride, reduction is effected. Method a. Exposure to 25% formic acid in the dark for 6 hr. When intramuscular nerves are visible, the muscle is further teased with glass instruments. Reduction is continued for an additional 18 hr in 25% formic acid, and the tissue is cleared in glycerol for 24 hr. Method b. Exposure to intense artificial visible light while the tissue is just immersed in distilled water at 37° C. Colour develops in the nerve endings as in a photographic print. When nerves only are stained (approximately 0.5 hr), the lamp is removed and microdissection at room temperature commenced. When nerve endings in muscle spindles are just visible (approximately 1 hr), the distilled water is replaced by glycerol. After either method of reduction, areas of motor end-plates and individual sensory receptors are isolated by microdissection. Preparations are mounted in a small drop of glycerol, considerable pressure is applied to the cover slip, and the cover ringed with a sealing fluid.  相似文献   

7.
Cholinesterase development was studied biochemically and histochemically in monolayer cultures of muscle cells from 10 day chick embryo leg muscle. Cholinesterase activity was low in myoblasts but increased rapidly after cell fusion and myotube formation; activity was distributed unevenly throughout myotubes, older fibres having some small areas of intense activity. Total Cholinesterase activity increased over the 10 day culture period while soluble activity reached a plateau after 4 days and was between 30–40% of the total. Butyrylcholines-terase activity did not change significantly during the period of study, comprising about 12% of the total Cholinesterase activity at 10 days. The possible effects on Cholinesterase development of combining muscle with dissociated spinal cord cells and with spinal cord explants, and of growing muscle in medium from which non-specific neural factors had been removed, was examined. No evidence was found for a nerve trophic effect on the amount or on the localization of muscle Cholinesterases.  相似文献   

8.
The tibial nerve transection model is a well-tolerated, validated, and reproducible model of denervation-induced skeletal muscle atrophy in rodents. Although originally developed and used extensively in the rat due to its larger size, the tibial nerve in mice is big enough that it can be easily manipulated with either crush or transection, leaving the peroneal and sural nerve branches of the sciatic nerve intact and thereby preserving their target muscles. Thus, this model offers the advantages of inducing less morbidity and impediment of ambulation than the sciatic nerve transection model and also allows investigators to study the physiologic, cellular and molecular biologic mechanisms regulating the process of muscle atrophy in genetically engineered mice. The tibial nerve supplies the gastrocnemius, soleus and plantaris muscles, so its transection permits the study of denervated skeletal muscle composed of fast twitch type II fibers and/or slow twitch type I fibers. Here we demonstrate the tibial nerve transection model in the C57Black6 mouse. We assess the atrophy of the gastrocnemius muscle, as a representative muscle, at 1, 2, and 4 weeks post-denervation by measuring muscle weights and fiber type specific cross-sectional area on paraffin-embedded histologic sections immunostained for fast twitch myosin.  相似文献   

9.
Radioautographs of 45Ca-labeled frog skeletal muscles have been prepared using freeze-dry and vapor fixation techniques to avoid displacement of the isotope during the preparation of the radioautographs. 45Ca has been localized in resting muscles exposed to 45Ca Ringer's for 5 min or 5 hr and in isotopically labeled muscles recovering from tetanic stimulation at room temperature or at 4°C. In muscles soaked at rest for 5 min 45Ca was present almost exclusively in the terminal cisternae. In all other muscles there were three sites at which the isotope was concentrated: (a) the terminal cisternae, (b) the intermediate cisternae and the longitudinal tubules, and (c) the A band portion of the myofibrils. The terminal cisternae were labeled more rapidly than the myofibrils, but both exchanges were accelerated by electrical stimulation. The amount of 45Ca in the longitudinal tubules and the intermediate cisternae decreased with time after a tetanus as the amount in the terminal cisternae increased. It is proposed that electrical stimulation releases calcium from the terminal cisternae and that relaxation occurs from the binding of the released calcium by the longitudinal tubules and the intermediate cisternae. Complete recovery from mechanical activity involves the transport of this bound calcium into the reticulum and its subsequent binding by the terminal cisternae. Resting exchange of calcium occurs primarily between the terminal cisternae and the transverse tubules.  相似文献   

10.
The purpose of this research was to assess the potential for far-infrared ray irradiation from ceramic powder to improve exercise performance at room temperature. We designed experiments with murine myoblast cells (C2C12) to study the effect of cFIR irradiation on cell viability and lactate dehydrogenase release under H2O2-mediated oxidative stress and evaluated intracellular levels of nitric oxide and calmodulin. We also used electro-stimulation of amphibian skeletal muscle. Our results show that cFIR strengthened C2C12 under oxidative stress and delayed onset of fatigue induced by muscle contractions. We discuss possible mechanisms including anti-oxidation and prevention of acid build-up in muscle tissue based, and expect to see more applications of cFIR in the future.  相似文献   

11.
Abstract

The process of muscular atrophy following denervation has been tentatively ascribed to the influence of glucocorticoids (G) because of the rapid increase of cytosolic G receptors (RG) after sciatic nerve section. It appears however that the level of muscular atrophy is similar: 1. in slow or fast-twitch muscles in spite of huge variations in RG; 2. in intact or adrenalectomized (ADR-X) rats. Moreover, the protein muscle profile of intact or ADR-X rats after gel electrophoresis is similar but drastically decreased after 3 weeks of denervation. We conclude that there is no causeeffect relationship between muscle atrophy and RG elevation after nerve section.  相似文献   

12.
肌肉生长抑制素基因的研究进展   总被引:16,自引:1,他引:16  
姜运良  连正兴  李宁  吴常信 《遗传》2000,22(2):119-121
  相似文献   

13.
The intracellular lactate shuttle hypothesis posits that lactate generated in the cytosol is oxidized by mitochondrial lactate dehydrogenase (LDH) of the same cell. To examine whether skeletal muscle mitochondria oxidize lactate, mitochondrial respiratory oxygen flux (JO2) was measured during the sequential addition of various substrates and cofactors onto permeabilized rat gastrocnemius muscle fibers, as well as isolated mitochondrial subpopulations. Addition of lactate did not alter JO2. However, subsequent addition of NAD+ significantly increased JO2, and was abolished by the inhibitor of mitochondrial pyruvate transport, α-cyano-4-hydroxycinnamate. In experiments with isolated subsarcolemmal and intermyofibrillar mitochondrial subpopulations, only subsarcolemmal exhibited NAD+-dependent lactate oxidation. To further investigate the details of the physical association of LDH with mitochondria in muscle, immunofluorescence/confocal microscopy and immunoblotting approaches were used. LDH clearly colocalized with mitochondria in intact, as well as permeabilized fibers. LDH is likely localized inside the outer mitochondrial membrane, but not in the mitochondrial matrix. Collectively, these results suggest that extra-matrix LDH is strategically positioned within skeletal muscle fibers to functionally interact with mitochondria.  相似文献   

14.
Abstract: The levels of neurotrophin mRNA in sensory ganglia, sciatic nerve, and skeletal muscle were measured in the streptozotocin-diabetic rat using northern blotting. Periods of diabetes of 4, 6, and 12 weeks significantly elevated brain-derived neurotrophic factor (BDNF) mRNA levels in soleus muscle compared with age-matched controls, the increase being highest at 6 weeks. At all time periods studied, the levels of nerve growth factor (NGF) mRNA in soleus muscle were decreased by 21–47%. Following 12 weeks of diabetes, BDNF mRNA levels were increased approximately two-to threefold in L4 and L5 dorsal root ganglia (DRG), and in sciatic nerve, NGF mRNA levels were raised 1.65-fold. Intensive insulin treatment of diabetic rats for the final 4 weeks of the 12-week period of diabetes reversed the up-regulation of BDNF mRNA in DRG and muscle and NGF mRNA in sciatic nerve. All diabetes-induced changes in neurotrophin mRNA were not paralleled by similar alterations in the levels of β-actin mRNA in muscle and nerve, or of GAP-43 mRNA in DRG and nerve. It is proposed that the up-regulation of neurotrophin mRNA is an endogenous protective and/or repair mechanism induced by insult and, as such, appears as an early marker of peripheral nerve and muscle damage in experimental diabetes.  相似文献   

15.
16.
Despite advances in surgical techniques for peripheral nerve repair, functional restitution remains incomplete. The timing of surgery is one factor influencing the extent of recovery but it is not yet clearly defined how long a delay may be tolerated before repair becomes futile. In this study, rats underwent sciatic nerve transection before immediate (0) or 1, 3, or 6 months delayed repair with a nerve graft. Regeneration of spinal motoneurons, 13 weeks after nerve repair, was assessed using retrograde labeling. Nerve tissue was also collected from the proximal and distal stumps and from the nerve graft, together with the medial gastrocnemius (MG) muscles. A dramatic decline in the number of regenerating motoneurons and myelinated axons in the distal nerve stump was observed in the 3- and 6-months delayed groups. After 3 months delay, the axonal number in the proximal stump increased 2–3 folds, accompanied by a smaller axonal area. RT-PCR of distal nerve segments revealed a decline in Schwann cells (SC) markers, most notably in the 3 and 6 month delayed repair samples. There was also a progressive increase in fibrosis and proteoglycan scar markers in the distal nerve with increased delayed repair time. The yield of SC isolated from the distal nerve segments progressively fell with increased delay in repair time but cultured SC from all groups proliferated at similar rates. MG muscle at 3- and 6-months delay repair showed a significant decline in weight (61% and 27% compared with contra-lateral side). Muscle fiber atrophy and changes to neuromuscular junctions were observed with increased delayed repair time suggestive of progressively impaired reinnervation. This study demonstrates that one of the main limiting factors for nerve regeneration after delayed repair is the distal stump. The critical time point after which the outcome of regeneration becomes too poor appears to be 3-months.  相似文献   

17.
何为  刘俐 《生物数学学报》1999,14(4):463-469
重点讨论了应用电磁场数值计算方法求解心电图正问题和逆问题中人体骨骼肌肉层的各向异性导电性的处理方法.文中应用有限元和边界元结合的方法,构造了一个包含不同的纤维方向组合的骨骼肌肉层的三维胸腔模型,并在此模型下引入了局部坐标内的各向异性导电率向整体坐标转换的方法.据此进行的模拟计算结果以图像的方式清晰地展示了各向异性导电性对体表电位图的影响.  相似文献   

18.
Muscle spindles were isolated from freshly removed cat lumbrical muscles in oxygenated Ringer's solution and placed in a solution containing 10 ml of 0.1% nitro blue tetrazolium and 10 ml of 0.2 M phosphate buffered sodium succinate, pH 7.6. Spindles were incubated in this solution at 37 C for 4-12 hr, returned to Ringer's for 30 min at room temperature, fixed in 10% formal-Ringer's for 30 min, and stored indefinitely in distilled water. With this technique the patterns of sensory innervation can be clearly visualized by the deposition of diformazan. The stained preparations may be mounted in glycerol and teased further for whole mount inspection or they may be embedded in Epon and serially sectioned for more detailed study.  相似文献   

19.
20.
The aim of this study is to present a detailed continuum mechanics formulation, and the corresponding algorithms, to predict the deformation of skeletal muscle at different structural levels, starting from the muscle fiber level. The model is used to investigate force production and structural changes during isometric and dynamic contractions of the cat medial gastrocnemius. From a comparison with experimental data obtained in our own laboratories, we conclude that the model faithfully predicts all of the observations pertaining to force production, fascicle length and angle of pennation under various test conditions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号