Expression patterns of initiator and effector caspases in denervated human skeletal muscle

There is evidence that apoptotic cell death contributes to the loss of denervated muscle fibers. In 17 patients with neurogenic muscular atrophy, we studied the expression of the apoptosis mediators APAF-1/caspase-9 and degrading caspases-2, -3, and -7 by immunohistochemical and western blot analyses. Muscle with neurogenic atrophy showed distinct upregulation of caspase-9 and -7 and no expression for APAF-1 (apoptosis protease-activating factor-1) and caspase-2 and -3. Expression of caspase-7 was restricted to atrophic fibers, but caspase-9 was also found in normal-sized muscle fibers where its expression was often confined to single fiber segments. These findings indicate that upregulated expression of caspase-9 can initiate the proteolytic cascade involving the downstream executioner caspase-7, which mediates degradation of denervated muscle fibers. However, apoptotic events may be restricted to single muscle-fiber segments, where apoptotic cell degradation contributes to the long-term process of atrophy. Pharmacological inhibition of caspases may be a therapeutic strategy in diminishing muscle atrophy.     

Computerized tomography and magnetic resonance muscle imaging in Miyoshi's myopathy

We describe clinical, pathological, and muscle imaging findings in a patient with an early adult-onset progressive muscular weakness in association with atrophy beginning in the legs and involving both gastrocnemi in particular. Muscle biopsy findings showed a severe dystrophic process with no vacuoles, consistent with Miyoshi's myopathy. Computerized tomography and magnetic resonance imaging scans were used to provide an ongoing permanent record of the various stages of the disease. © 1996 John Wiley & Sons, Inc.     

Regenerative cell injection in denervated muscle reduces atrophy and enhances recovery following nerve repair

Introduction: Functional muscle recovery after peripheral nerve injury is far from optimal, partly due to atrophy of the muscle arising from prolonged denervation. We hypothesized that injecting regenerative cells into denervated muscle would reduce this atrophy. Methods: A rat sciatic nerve lesion was performed, and Schwann cells or adipose‐derived stem cells, untreated or induced to a “Schwann‐cell–like” phenotype (dASC), were injected into the gastrocnemius muscle. Nerves were either repaired immediately or capped to prevent muscle reinnervation. One month later, functionality was measured using a walking track test, and muscle atrophy was assessed by examining muscle weight and histology. Results: Schwann cells and dASC groups showed significantly better scores on functional tests when compared with injections of growth medium alone. Muscle weight and histology were also significantly improved in these groups. Conclusion: Cell injections may reduce muscle atrophy and could benefit nerve injury patients. Muscle Nerve 47: 691–701, 2013     

Focal atrophy of the multifidus muscle in lumbosacral radiculopathy

A patient with compelling clinical and electrodiagnostic evidence of a right L5 radiculopathy had focal atrophy of the multifidus at the appropriate level, which served to confirm the radicular nature of the process. The multifidus muscles are innervated by a single root, in contrast to the polysegmental innervation of the rest of the paraspinal muscle mass. Imaging studies may complement needle electromyography in the evaluation of this important structure. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1350–1353, 1998.     

Clinical characteristics of muscle cramps in hereditary angiopathy with nephropathy,aneurysms, and muscle cramps syndrome associated with a novel COL4A1 pathogenic variant: A family case study

BackgroundMuscle cramps are a common problem characterized by a sudden, painful, and involuntary contraction of a muscle or muscle group. Most muscle cramps develop in the calf muscles, particularly in situations of prolonged exercise; however, some may be related to underlying systemic conditions such as the hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC) syndrome. Muscle cramps appear to be the initial symptom of the HANAC syndrome; however, the clinical characteristics of these muscle cramps have rarely been described in detail.Case presentationWe report a familial case of autosomal-dominant muscle cramps in four members of a Japanese family spanning across three generations. The muscle cramps were recognized as systemic symptoms of the HANAC syndrome associated with a novel COL4A1 pathogenic variant, NM_001845:c.1538G > A, p.(Gly513Asp). The four affected individuals indicated that the first episodes of the muscle cramps occurred in early childhood. In addition, they reported that the muscle cramps are characterized by an abrupt onset of severe pain without muscle contraction. The painful recurrent attacks occurred spontaneously in various muscles throughout the body, but rarely in the calf muscle. The muscle pain lasts for several minutes, cannot be ameliorated by stretching the affected muscle, and leaves a feeling of discomfort that lasts for 24–48 h. The serum creatine kinase levels of the patients were persistently elevated; however, their electromyography results did not reveal any specific abnormalities.ConclusionsRecognition of the clinical characteristics of the muscle cramps in the HANAC syndrome may facilitate early diagnosis of the syndrome and enable proper treatment of the patients, improve their long-term outcomes, and facilitate the design and adaption of appropriate genetic counseling.     

Proteomic analysis of mouse soleus muscles affected by hindlimb unloading and reloading

Introduction: Disuse muscle atrophy, induced by prolonged space flight, bed rest, or denervation, is a common process with obvious changes in slow‐twitch soleus muscles. Methods: Proteomic analysis was performed on mouse soleus subjected to hindlimb unloading (HU) and hindlimb reloading (HR) to identify new dysregulated proteins. Results: Following HU, the mass and cross‐sectional area of muscle fibers decreased, but they recovered after HR. Proteomic analyses revealed 9 down‐regulated and 7 up‐regulated proteins in HU, and 2 down‐regulated and 5 up‐regulated proteins in HR. The dysregulated proteins were mainly involved in energy metabolism, protein degradation, and cytoskeleton stability. Among the dysregulated proteins were fatty acid binding protein 3, α‐B crystalline, and transthyretin. Conclusions: These results indicate that muscle atrophy induced by unloading is related to activation of proteolysis, metabolic alterations toward glycolysis, destruction of myofibrillar integrity, and dysregulation of heat shock proteins (HSPs). The dysregulated proteins may play a role in muscle atrophy and the recovery process. Muscle Nerve 52 : 803–811, 2015     

The role of skeletal muscle biopsy in the diagnosis of neuromuscular disorders

Muscle biopsy is required to provide a definitive diagnosis in many neuromuscular disorders. Biopsy findings may indicate whether the pathological process is of neurogenic or myopathic origin. The muscle biopsy may give important information on the course of the disease (acute or chronic) and on the disease stage and progression. The interpretation of muscle biopsy, including histochemical and ultrastructural analysis, is a key factor in the diagnosis of muscular dystrophies, glycogenoses, inflammatory myopathies and congenital myopathies. An assessment of muscle biopsy on electron microscopy enables a definite diagnosis of oculopharyngeal muscular dystrophy, mitochondrial myopathy or inclusion body myositis. This paper presents an overview of general indications for muscle biopsy, biopsy procedures, as well as transportation and preparation of muscle tissue for final microscopic analysis. The interpretation of specific microscopic findings and a brief discussion on the clinical usefulness of muscle biopsy in the era of molecular diagnosis are also presented.     

抗核基质蛋白2抗体阳性炎性肌病临床及病理分析

目的 探讨抗核基质蛋白2（NXP2）抗体阳性炎性肌病患者的临床表现、肌肉病理特点和治疗。方法 回顾性分析就诊于我院的4例抗NXP2抗体阳性炎性肌病患者的临床表现、肌肉病理改变和治疗方法。结果 4例患者均出现对称性四肢近端无力,2例出现皮肌炎样皮疹,3例出现吞咽困难,2例出现肢体水肿。3例血清肌酸激酶显著升高,1例正常;4例肌电图均为肌源性损害;4例下肢肌肉磁共振显示肌肉及筋膜组织水肿信号;4例血清抗NXP2抗体阳性。肌肉病理3例表现为束周萎缩,血管周围和肌束膜炎性细胞浸润;1例表现为间质水肿。4例患者均给予糖皮质激素治疗,随访3例患者好转,1例出院后意外死亡。结论 抗NXP2抗体阳性炎性肌病以皮肌炎为主要临床表现,多伴有吞咽困难和肢体水肿,肌肉磁共振显示肌肉及筋膜水肿信号;主要病理特点为束周萎缩;糖皮质激素治疗效果较好。     

成人型近端脊髓性肌萎缩症的临床和肌肉病理学研究

目的 总结成人型近端脊髓性肌萎缩症(ASMA)临床和肌肉病理学特征，以提高对ASMA的认识。方法 对27例完成肌肉活检的ASMA患者进行临床及肌肉病理学分析。结果 该病多于45岁左右发病，起病及进展均缓慢，主要表现为近端肌肉无力、肌肉萎缩、肌束震颤，锥体束和周围神经一般不受累。4例患者肌酶增高。所有患者肌电图检查示神经源性损害，其中2例伴肌源性改变。肌肉活检光镜下见神经源性肌萎缩，其中3例伴肌源性损害。电镜下见肌原纤维数量减少、排列紊乱、部分断裂，Z线变粗或呈波浪样以及肌核聚集。结论 结合临床表现进行肌肉活检对ASMA诊断及鉴别诊断具有重要价值。     

Distal spinal muscular atrophy featured by predominant calf muscle involvement in VRK1 associated disease – Case series and review

We describe the shared clinical, biochemical, radiological and myopathological characteristics of four patients with distal spinal muscular atrophy (dSMA) caused by vaccinia-related kinase 1 (VRK1) variants and provide a review of the literature on phenotype-genotype correlations in VRK1-related disease. The clinical phenotype was characterized by adult-onset dSMA with predominant calf muscle involvement and mildly elevated serum creatinine kinase (CK) levels. Muscle imaging showed predominant atrophy and fatty replacement of calf muscles. We identified the novel compound heterozygous variants c.607C>T (p.Arg203Trp) and c.858G>T (p.Met286Ile) in two siblings with adult-onset dSMA. Additionally, two unrelated patients both carried the known c.583T>G (p.Leu195Val) VRK1 variant, with either c.197C>G (p.Ala66Gly) or c.701A>G (p.Asn234Ser) as a second variant. We conclude that compound heterozygous VRK1 variants cause distal spinal muscular atrophy with predominant posterior leg muscle involvement.     

Muscle proteins during 60‐day bedrest in women: Impact of exercise or nutrition

Almost no data exist regarding skeletal muscle responses to real or simulated spaceflight in women. We determined the impact of 60‐day bedrest (BR, n = 8), 60‐day bedrest with exercise‐training (BRE, n = 8), and 60‐day bedrest with a leucine‐enriched, high‐protein diet (BRN, n = 8) on muscle protein composition. Vastus lateralis and soleus muscle biopsies were analyzed for global protein fractions (mixed, sarcoplasmic, myofibrillar) and force‐specific proteins (myosin, actin, collagen). Concentrations (micrograms per milligram muscle wet weight) of these proteins were maintained (P > 0.05) in BR, despite large changes in quadriceps (?21%) and triceps surae (?29%) volume. Neither countermeasure influenced muscle protein content in either muscle (P > 0.05), despite exacerbation (BRN) or prevention (BRE) of atrophy. Pre‐bedrest comparisons showed less myofibrillar protein in the soleus (?16%, P < 0.05), primarily due to less myosin (?12%, P < 0.05) and more collagen (234%, P < 0.05) than the vastus lateralis. Muscle protein composition is tightly regulated in lower limb muscles of women, despite the most extreme weightlessness‐induced atrophy reported in humans. In contrast, men who underwent prolonged unloading were unable to proportionally regulate atrophy of the soleus. These findings have implications for astronauts and clinical conditions of sarcopenia regarding the maintenance of muscle function and prevention of frailty. Muscle Nerve, 2008     

Skeletal muscle ultrasound

Abstract

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Muscle ultrasound is a convenient technique to visualize normal and pathological muscle tissue as it is non-invasive and real-time. Neuromuscular disorders give rise to structural muscle changes that can be visualized with ultrasound: atrophy can be objectified by measuring muscle thickness, while infiltration of fat and fibrous tissue increases muscle echo intensity, i.e. the muscles become whiter on the ultrasound image. Muscle echo intensity needs to be quantified to correct for age-related increase in echo intensity and differences between individual muscles. This can be done by gray scale analysis, a method that can be easily applied in daily clinical practice. Using this technique, it is possible to detect neuromuscular disorders with predictive values of 90%. Only in young children and metabolic myopathies the sensitivity is lower. Ultrasound is a dynamic technique and therefore capable of visualizing normal and pathological muscle movements. Fasciculations can easily be differentiated from other muscle movements. Ultrasound appeared to be even more sensitive in detecting fasciculations compared to Electromyography (EMG) and clinical observations, because it can visualize a large muscle area and deeper located muscles. With improving resolution and frame rate it has recently become clear that also smaller scale spontaneous muscle activity such as fibrillations can be detected by ultrasound. This opens the way to a broader use of muscle ultrasound in the diagnosis of peripheral nerve and muscle disorders.     

Perioral skin biopsy to study skeletal muscle protein expression

Clinical trials for muscular dystrophy molecular treatment require multiple sampling of skeletal muscle to monitor protein rescue. This practice is invasive and could raise ethical problems. A less invasive tool to obtain sequential muscle sampling is necessary. Using indirect immunofluorescence, we evaluated muscle protein expression in myofiber bundles included in 2–2.5‐mm punch skin biopsies from the perioral region from 6 healthy subjects and 6 patients with genetically defined forms of muscular dystrophy. Large intradermal bundles of orbicularis oris muscle were constantly present in skin biopsies. They showed a typical muscular antigenic pattern in controls and the expected protein defect in muscular dystrophy patients. These results demonstrate the feasibility of muscular protein expression analysis using skin biopsy. We propose this minimally invasive technique to follow‐up the response to genetic or conventional therapies in muscular dystrophies and to confirm the diagnosis in some special clinical conditions. Muscle Nerve 41: 392–398, 2010     

Thigh muscle volume measured by magnetic resonance imaging is stable over a 6-month interval in spinal muscular atrophy

Changes in thigh muscle volume over 6 months were assessed using magnetic resonance imaging in 11 subjects aged 6 to 47 years with spinal muscular atrophy (4 type 2 and 7 type 3; 4 ambulatory and 3 nonambulatory). Muscle volume with normal and abnormal signal was measured using blinded, semiautomated analysis of reconstructed data. Volumes at baseline and 6 months were correlated with clinical function at each epoch. There was minimal increase in normal (0.3 ± 1.4 mL/cm) and total (0.1 ± 1.3 mL/cm) muscle. Muscle volume correlated closely with clinical function. Minimal interval change in muscle volume is consistent with the established clinical history of minimal disease progression over intervals shorter than 1 year. Relative constancy of muscle volume estimation and correlation with established functional measures suggest a role for segmental magnetic resonance imaging as a biomarker of treatment effect in future therapeutic trials.     

抗核基质蛋白2抗体阳性炎性肌病临床及病理分析

目的探讨抗核基质蛋白2(NXP2)抗体阳性炎性肌病患者的临床表现、肌肉病理特点和治疗。方法回顾性分析就诊于我院的4例抗NXP2抗体阳性炎性肌病患者的临床表现、肌肉病理改变和治疗方法。结果 4例患者均出现对称性四肢近端无力,2例出现皮肌炎样皮疹,3例出现吞咽困难,2例出现肢体水肿。3例血清肌酸激酶显著升高,1例正常;4例肌电图均为肌源性损害;4例下肢肌肉磁共振显示肌肉及筋膜组织水肿信号;4例血清抗NXP2抗体阳性。肌肉病理3例表现为束周萎缩,血管周围和肌束膜炎性细胞浸润;1例表现为间质水肿。4例患者均给予糖皮质激素治疗,随访3例患者好转,1例出院后意外死亡。结论抗NXP2抗体阳性炎性肌病以皮肌炎为主要临床表现,多伴有吞咽困难和肢体水肿,肌肉磁共振显示肌肉及筋膜水肿信号;主要病理特点为束周萎缩;糖皮质激素治疗效果较好。     

Muscle ultrasound in neuromuscular disorders

Muscle ultrasound is a useful tool in the diagnosis of neuromuscular disorders, as these disorders result in muscle atrophy and intramuscular fibrosis and fatty infiltration, which can be visualized with ultrasound. Several prospective studies have reported high sensitivities and specificities in the detection of neuromuscular disorders. Although not investigated in large series of patients, different neuromuscular disorders tend to show specific changes on muscle ultrasound, which can be helpful in differential diagnosis. For example, Duchenne muscular dystrophy results in a severe, homogeneous increase of muscle echo intensity with normal muscle thickness, whereas spinal muscular atrophy shows an inhomogeneous increase of echo intensity with severe atrophy. A major advantage of muscle ultrasound, compared to other imaging techniques, is its ability to visualize muscle movements, such as muscle contractions and fasciculations. This study reviews the possibilities and limitations of ultrasound in muscle imaging and its value as a diagnostic tool in neuromuscular disorders.     

单纯血清肌酶升高患者肌活检病理分析

目的 通过分析单纯血清肌酶升高患者的肌肉病理诊断,了解单纯血清肌酶升高患者的病因.方法 采用归纳分析法分析了24例单纯血清肌酶升高患者的人口学资料、血清肌酶水平、肌电图及病理特点.结果 男性16例,女性8例,年龄3岁～54岁,平均年龄(32.56±15.93)岁.血清CK波动于577.40～17720.00 U/L之间,平均(8081.83±6065.50)U/L,LDH波动于150.20～ 1643.80 U/L之间,平均(415.30±324.90) U/L.20例患者肌电图检查提示,15例为肌源性损害,3例正常,1例可疑肌源性损害,1例仅表现为运动单位时限偏短.肌肉病理提示2例为正常(8.33％)、5例(20.83％)为非特异性散在肌萎缩以及17例为肌病(70.83％),肌病包括肌营养不良13例(54.17％),炎性肌病组3例(12.50％)和Danon病1例(4.17％).结论 无症状性单纯血清肌酶升高患者的病因较多,肌肉酶组织化学和免疫组织化学可以协助多数患者的病因诊断.     

Apigenin inhibits sciatic nerve denervation–induced muscle atrophy

Introduction: Apigenin (AP) has been reported to elicit anti‐inflammatory effects. In this study, we investigated the effect of AP on sciatic nerve denervation–induced muscle atrophy. Methods: Sciatic nerve–denervated mice were fed a 0.1% AP‐containing diet for 2 weeks. Muscle weight and cross‐sectional area (CSA), and the expression of atrophic genes and inflammatory cytokines in the gastrocnemius were analyzed. Results: Denervation significantly induced muscle atrophy. However, values for muscle weight and CSA were greater in the denervated muscle of the AP mice than the controls. AP suppressed the expression of MuRF1, but upregulated both myosin heavy chain (MHC) and MHC type IIb. AP also significantly suppressed expression of tumor necrosis‐alpha in the gastrocnemius and soleus muscles, and interleukin‐6 expression in the soleus muscle. Discussion: AP appears to inhibit denervation‐induced muscle atrophy, which may be due in part to its inhibitory effect on inflammatory processes within muscle. Muscle Nerve 58 : 314–318, 2018     

The pathology of the muscle spindle in Duchenne muscular dystrophy.

Muscle spindles have been studied in 7 autopsied cases of Duchenne muscular dystrophy. The autopsies of 2 boys of similar age who died without known neuromuscular disease were used as controls. The abnormalities found consisted of degenerative changes, atrophy and loss of intrafusal muscle fibres, thickening of the spindle capsule and widening of the periaxial space. In some very severely affected muscles there was evidence that spindles were destroyed in the course of the disease. Statistical comparison of these observations was made between the pathological and normal material. The muscle spindle innervation appeared normal in sectioned material. Teased preparations were not available for study.