用骨骼肌桥接神经缺损的进一步研究

用大白鼠作骨骼肌桥接周围神经缺损的实验研究,观察到再生的运动神经纤维多数进入远端与运动神经相接处,只有少数进入与感觉神经相接处.实验证明再生神经纤维有功能性定向生长的趋向。     

T2, T1ρ and TRAFF4 detect early regenerative changes in mouse ischemic skeletal muscle

The identification of areas with regenerative potential in ischemic tissues would allow the targeting of treatments supporting tissue recovery. The regeneration process involves the activation of several cellular and molecular responses which could be detected using magnetic resonance imaging (MRI). However, to date, magnetic resonance (MR) relaxation parameters have received little attention in the diagnosis and follow‐up of limb ischemia. The purpose of this study was to evaluate the feasibility of different MRI relaxation and diffusion tensor imaging parameters in the detection of areas showing early signs of regeneration in ischemic mouse skeletal muscles. T₂ and T_1ρ relaxation time constants, together with T_RAFFn, T₁ and diffusion tensor imaging, were evaluated to differentiate areas of regeneration in a mouse hind limb ischemia model before and 0, 1, 4, 7, 14 and 30 days after ischemia. All the measured relaxation times were longer in the areas of early regeneration compared with normal muscle tissue. The relaxation times increased after ischemia in the ischemic muscles, reaching a maximum at 4–7 days after occlusion, coinciding with the appearance of early signs of regeneration. Fractional anisotropy decreased significantly (p < 0.05) on days 1–4, whereas mean diffusivity, λ₁ and λ₂ decreased later, starting at day 7 after ischemia compared with the pre‐operational time point. The percentages of areas with different tissue morphologies were determined based on histological analysis of the ischemic muscle cross‐sections, and correlations between the percentages obtained and different relaxation times were calculated. The highest correlation between relaxation times and histology was achieved with T₂, T_1ρ and T_RAFF4 (R² = 0.96, R² = 0.92 and R² = 0.84, respectively, p < 0.01)_. Early regenerative changes were visible using T₂, T_1ρ and T_RAFF4 MR relaxation time constants in skeletal muscle after ischemia. These markers could potentially be used for the identification of targets for therapies supporting muscle regeneration after ischemic injury.     

HRP法对骨骼肌桥接周围神经缺损的评价

用大鼠作为实验模型,切除6mm 坐骨神经,用骨骼肌桥接修复神经缺损,术后12周用 HRP 逆行示踪法,见到脊髓腰段前角和腰下部后根神经节内出现标记细胞,证实肌桥能修复周围神经的连续性.     

Platelet components today

Platelet concentrates (PC) continues to be the only resource available to treat patients with qualitative and/or quantitative platelet defects. Currently we have three methods to prepare PC: platelet rich plasma (PRP), buffy coat (BC), and apheresis. In recent years, the characteristics of the products have improved significantly: greater yield of better platelets with less RBC and leucocyte content. At the present, BC and apheresis derived PC offer some advantages in comparison to PRP, as it can been prepared in additive solutions, culture them using sensitive methods or apply pathogen reduction technologies.     

Satellite cells express the trophic factor IGF-I in regenerating skeletal muscle

The expression of insulin-like growth factor I (IGF-I, somatomedin C) was studied in regenerating skeletal muscle. Irreversible damage to skeletal muscle cells was induced in the extensor digitorum longus muscle (EDL) of adult rats by ischaemia, preceded by glycogen depletion, and the regeneration process was studied for periods up to 14 days after injury. The IGF-I was demonstrated by indirect immunofluorescence. Immunoreactivity against ribonucleotide reductase (RR) was used as a marker for DNA synthesis, that is, cell proliferation. Increased IGF-I immunoreactivity could be demonstrated within 24h after injury in satellite cells, intramuscular nerves and in blood vessels. The IGF-I immunoreactivity remained virtually unchanged in the contralateral, undamaged EDL. An increasing number of satellite cells, expressing high IGF-I immunoreactivity, could be demonstrated in the injured EDL, and within 72 h myoblasts, expressing high IGF-I and RR immunoreactivity, were formed. Small immature muscle cells, displaying high IGF-I immunoreactivity, were observed 4 days after injury. Increased IGF-I immunoreactivity was still obvious in the regenerated muscle cells 14 days after injury while RR immunoreactivity was seen only in scattered satellite cells. It is concluded that IGF-I may act as a trophic factor during regeneration of skeletal muscle after injury.     

Targeted gene delivery to differentiated skeletal muscle: A tool to study dedifferentiation

Cellular dedifferentiation is required for functional regeneration in salamanders. Dedifferentiating multinucleate skeletal muscle gives rise to mononucleate cells during limb regeneration. Efficient methods and tools must be developed in order to understand the molecular cues underlying dedifferentiation. Here we describe a non‐viral method to express extra‐chromosomal DNA exclusively in terminally differentiated muscle without the need for cell purification steps. After cytoplasmic injection of various expression vectors into myotubes or myofibres, we detect long‐lasting mRNA and protein expression in up to 70% of the injected cells. The combination of the transfection protocol with live imaging allows a time‐ and cost‐effective screen of candidate genes in terminally differentiated muscle cells of both amphibian and mammalian origin. Developmental Dynamics 236:481–488, 2007. © 2006 Wiley‐Liss, Inc.     

Toll‐like receptor signalling in regenerative myogenesis: friend and foe

Skeletal muscle regeneration in normal and diseased muscle is regulated by multiple factors and cells present in the injured muscle micro‐environment. In addition to muscle progenitor cells, several immunocytes participate in the regenerative response. Among them, macrophages are one of the most important components of the immune response that governs the step‐wise progression of muscle regeneration. The initial role of macrophages is to phagocytose muscle cell debris and later, through their transition to an anti‐inflammatory phenotype, they promote regeneration. However, in several genetic muscle disorders, continuous muscle injury disrupts the balance between pro‐inflammatory and anti‐inflammatory macrophages, leading to an overall inflammatory milieu and inhibition of muscle regeneration. Accumulating evidence suggests that Toll‐like receptor (TLR)‐mediated signalling plays an important role in the regulation of macrophage phenotypes during regenerative myogenesis in response to both acute and chronic muscle injury. Here, we discuss the role of TLR signalling in regulating macrophage phenotypes and skeletal muscle regeneration in healthy and diseased muscle. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Acute resistance exercise increases skeletal muscle angiogenic growth factor expression

AIMS: Both aerobic and resistance exercise training promote skeletal muscle angiogenesis. Acute aerobic exercise increases several pro-angiogenic pathways, the best characterized being increases in vascular endothelial growth factor (VEGF). We hypothesized that acute resistance exercise also increases skeletal muscle angiogenic growth factor [VEGF and angiopoietin (Ang)] expression. METHODS: Seven young, sedentary individuals had vastus lateralis muscle biopsies and blood drawn prior to and at 0, 2 and 4 h post-resistance exercise for the measurement of VEGF; VEGF receptor [KDR, Flt-1 and neuropilin 1 (Nrp1)]; Ang1 and Ang2; and the angiopoietin receptor--Tie2 expression. Resistance exercise consisted of progressive knee extensor (KE) exercise to determine one repetition maximum (1-RM) followed by three sets of 10 repetitions (3 x 10) of KE exercise at 60-80% of 1-RM. RESULTS: Resistance exercise significantly increased skeletal muscle VEGF mRNA and protein and plasma VEGF protein at 2 and 4 h. Resistance exercise increased KDR mRNA and Tie2 mRNA at 4 h and Nrp1 mRNA at 2 and 4 h. Skeletal muscle Flt-1, Ang1, Ang2 and Ang2/Ang1 ratio mRNA were not altered by resistance exercise. CONCLUSIONS: These findings suggest that acute resistance exercise increases skeletal muscle VEGF, VEGF receptor and angiopoietin receptor expression. The increases in muscle angiogenic growth factor expression in response to acute resistance exercise are similar in timing and magnitude with responses to acute aerobic exercise and are consistent with resistance exercise promoting muscle angiogenesis.     

Structure, distribution and innervation of muscle spindles in avian fast and slow skeletal muscle

Muscle spindles in 2 synergistic avian skeletal muscles, the anterior (ALD) and posterior (PLD) latissimus dorsi, were studied by light and electron microscopy to determine whether morphological or quantitative differences existed between these sensory receptors. Differences were found in the density, distribution and location of muscle spindles in the 2 muscles. They also differed with respect to the morphology of their capsules and intracapsular components. The slow ALD possessed muscle spindles which were evenly distributed throughout the muscle, whereas in the fast PLD they were mainly concentrated around the single nerve entry point into the muscle. The muscle spindle index (number of spindles per gram wet muscle weight) in the ALD was more than double that of its fast-twitch PLD counterpart (130.5±2.0 vs 55.4±2.0 respectively, n=6). The number of intrafusal fibres per spindle ranged from 1 to 8 in the ALD and 2 to 9 in the PLD, and their diameters varied from 5.0 to 16.0 μm and 4.5 to 18.5 μm, respectively. Large diameter intrafusal fibres were more frequently encountered in spindles of the PLD. Unique to the ALD was the presence of monofibre muscle spindles (12.7% of total spindles observed in ALD) which contained a solitary intrafusal fibre. In muscle spindles of both the ALD and PLD, sensory nerve endings terminated in a spiral fashion on the intrafusal fibres in their equatorial regions. Motor innervation was restricted to either juxtaequatorial or polar regions of the intrafusal fibres. Outer capsule components were extensive in polar and juxtaequatorial regions of ALD spindles, whereas inner capsule cells of PLD spindles were more numerous in juxtaequatorial and equatorial regions. Overall, muscle spindles of the PLD exhibited greater complexity with respect to the number of intrafusal fibres per spindle, range of intrafusal fibre diameters and development of their inner capsules. It is postulated that the differences in muscle spindle density and structure observed in this study reflect the function of the muscles in which they reside.     

CTGF/CCN-2 over-expression can directly induce features of skeletal muscle dystrophy

Muscular dystrophies are diseases characterized by muscle weakness together with cycles of degeneration and regeneration of muscle fibres, resulting in a progressive decrease of muscle mass, diminished muscle force generation and an increase in fibrosis. Fibrotic disorders are the endpoint of many chronic diseases in different tissues, where accumulation of the extracellular matrix (ECM) occurs. Connective tissue growth factor CTGF/CCN2, which is over-expressed in muscular dystrophies, plays a major role in many progressive scarring conditions. To test the hypothesis that CTGF might not only contribute conversion of already damaged muscle into scar tissue, but that it could by itself also directly contribute to skeletal muscle deterioration, we evaluated the effect of CTGF over-expression in tibialis anterior muscle of wild-type mice, using an adenovirus containing the CTGF mouse sequence (Ad-mCTGF). CTGF over-expression induced extensive skeletal muscle damage, which was followed by a massive regeneration of the damaged muscle, as evidenced by increased embryonic myosin and fibres with centrally located nuclei. It also induced strong fibrosis with increased levels of fibronectin, collagen, decorin and α-smooth muscle actin (α-SMA). Moreover, CTGF over-expression caused a decrease of the specific isometric contractile force. Strikingly, when CTGF over-expression stopped, the entire phenotype proved to be reversible, in parallel with normalization of CTGF levels. Thus, CTGF not merely acts downstream of muscle injury but also contributes directly to the deterioration of skeletal muscle phenotype and function. Moreover, normalization of expression levels led to spontaneous reversal of the CTGF-induced phenotype and to full recovery of muscle structure. These observations underscore the importance of CTGF in the pathophysiology of muscular dystrophies and suggest that targeting CTGF might have significant potential in the development of novel therapies for Duchenne muscular dystrophy and related diseases.     

骨骼肌蛋白质组学研究进展

骨骼肌组织以及肌肉蛋白为机体重要的组成部分,很多疾病以肌肉组织的特异性改变为特征。蛋白质组学技术的发展促进了骨骼肌蛋白质组学的研究,主要涉及细胞蛋白成分的整体分析,骨骼肌蛋白合成降解紊乱相关蛋白的识别与鉴定,以及衰老、肥胖和环境因素对骨骼肌的影响。蛋白质组学技术的应用,有利于发现与骨骼肌病理改变相关的诊断及预后指标,为临床治疗寻找潜在的药物靶标提供重要依据。     

Initial charge distribution and capacity transients in frog skeletal muscle

The effect of prior charge transfers on intramembrane charge movements was investigated in voltage-clamped frog skeletal muscle fibres. 10mV steps betweenfixed prepulse and test voltages were imposed at varying intervals after a 5mV prepulse step made from a previous conditioning level. The amount of charge transfer prior to the test step was varied by altering the extent to which the test step intercepted slow (q) currents elicited in the prepulse. The greater the prior charge transfer, the more rapid the transients in the subsequent test step. In contrast, where the prepulse had not reached the threshold of slow currents, or at larger depolarizations where the then faster charging currents were not intercepted, charge movements induced by the test step had a constant size and form. Charging kinetics thus varied with preceding charge transfer, consistent with higher-order cooperative (Huang, 1984), or sequential (Almers, 1978) schemes for the nonlinear charge.     

Comparative phenotypes in rhabdomyosarcomas and developing skeletal muscle

The morphological and immunohistochemical phenotypes of 51 rhabdomyosarcomas from young people have been described and contrasted with phenotypes in developing skeletal muscle from 20 fetuses and neonates. The tumours express markers in a cumulative and consistent sequence--vimentin, desmin, fast myosin, myoglobin--which evolves pari passu with morphological differentiation and follows the same pattern found in normal myogenesis. Changes in immunohistochemical phenotype are documented in residual and recurrent tumours excised after chemotherapy. The presumptive rhabdomyoblastic nature of some primitive tumours, marking with vimentin alone, is discussed.     

Expression of P2Y(6) receptors in the developing mouse skeletal muscle and after injury and repair

In this study, single and double-labeling immunofluorescence histochemistry, Western blot and real-time polymerase chain reaction were used to study the expression of P2Y(6) receptors in developing mouse skeletal muscle and during injury and repair. The results show that P2Y(6) receptor immunoreactive (ir) cells were first detected in the dermamyotome at embryonic (E) day 9. The number and immunostaining intensity of the P2Y(6) receptor-ir cells increased from E9 to E13, but decreased from E15 to postnatal day 60 in the developing skeletal muscle system. The expression levels of P2Y(6) receptor protein and mRNA increased rapidly from 1 to 5 days after skeletal muscle injury and then decreased almost to the control level from 7 to 10 days, at the beginning of regeneration. P2Y(6) receptor-immunoreactivity was mainly localized to the ends of single myoblasts and myotube processes in the developing and injury-repair skeletal muscle tissues. These data suggest that the P2Y(6) receptor may be involved in the development and regeneration of skeletal muscle, especially in the migration and extension of the myoblast and myotube in developing and regenerating skeletal muscle.     

Angiolymphoid hyperplasia with eosinophilia involving skeletal muscle

A vascular tumour involving the trapezius muscle is described. In addition to proliferating blood vessels with perithelial cuffing, there was a distinctive stroma of lymphoid aggregates, plasmacytoid cells, some mast cells and large numbers of eosinophils, many with a perivascular distribution. This solely intramuscular lesion was considered to be an example of angiolymphoid hyperplasia with eosinophilia. The aetiology and pathogenesis are discussed.     

骨骼肌桥接周围神经缺损效果的实验观察

用大白鼠7只,以骨骼肌桥接坐骨神经缺损8mm.术后4～6个月观察,再生神经纤维顺利地通过肌桥,肌组织巳为再生的神经纤维所取代,光镜和电镜下观察巳接近正常的神经组织.神经传导速度存活4个月的实验侧为正常侧的24.1%;5个月的为38.1%.肌力4个月的实验侧为正常侧的46.4%;5个月的为84.7%;六个月的为88.5%.     

Histopathological findings in skeletal muscle used in human dynamic cardiomyoplasty

Patients submitted to dynamic cardiomyoplasty had an initial clinical improvement followed by a decrease in cardiac failure indices. A histopathological study of the skeletal muscle was undertaken to explain this. Latissimus dorsi fragments from 15 patients submitted to dynamic cardiomyoplasty in a 1:1 (heart beat:muscle stimulation) conditioning were analysed by light microscopy. The interval between surgery and obtaining the specimens (13 from necropsies, two from heart transplants) ranged from 37 days to 6 years. Nuclear clumps and internalization, the presence of round fibres, inflammation, and fibrosis were analysed semi-quantitatively; the thickness of muscle fibres and the percentage of tissue fat were measured by image analysis. The quantitative data were also compared, in 12 cases, with gender- and age-matched necropsy controls. The mean thickness of muscle fibres in cases and controls was 27.21+/-5.33 and 40.84+/-9.42 microm, respectively (p=0.001). The percentage of tissue fat in cases and controls was 12.04+/-12.66% and 0.93+/-0.91%, respectively (p=0.008). The duration of grafts correlated positively with the quantity of nuclear clumps (R=0.80, p<0.001) and round fibres (R=0.53, p=0.04), as well as with the percentage of tissue fat (R=0.68, p=0.005). Accordingly, a negative correlation was found between the duration of grafts and the mean diameter of fibres, characterizing muscle atrophy (R=-0.66, p=0.01). The longer the post-surgical period, the more intense the degenerative lesions. This study shows that skeletal muscle used in human dynamic cardiomyoplasty may atrophy and be replaced by fat when stimulation is synchronized to every cardiac beat. These findings could play a role in explaining the long-term results of this surgical procedure.