Evaluation of triceps surae muscle length and resistance to passive lengthening in patients with acquired brain injury

OBJECTIVE: To examine changes in muscle length and resistance to passive lengthening in the triceps surae muscles in patients with recently acquired brain injury. BACKGROUND: Increased passive resistance in the triceps surae muscles is common following acquired brain injury. Adaptive shortening secondary to relative immobility, and increased stiffness due to rheologic changes within the musculo-tendinous unit, may be exacerbated by plantarflexor muscle overactivity related to the brain injury itself. DESIGN: Three variables representing resistance to passive lengthening and soleus muscle length were compared between subjects with recent brain injury and age matched normal controls. Comparison between limbs was made for subjects with unilateral neurological impairment. METHODS: Slow passive dorsiflexion stretches were performed using a computer controlled dynamometer. Muscle stiffness in the initial and latter portion of the range, and the angles achieved at torques of 5 and 10 N m were determined from torque-angle curves. Maximal ankle dorsiflexion with the knee flexed was considered to reflect soleus muscle length. RESULTS: Significant differences were demonstrated for all variables, except passive stiffness near the end of available range. The limb ipsilateral to unilateral brain injury differed from control limbs in that significantly less passive range of dorsiflexion was available and initial resistance to passive stretch was significantly less. CONCLUSIONS: The reduction in soleus muscle length evident in subjects with recent acquired brain injury, even in neurologically unaffected limbs, may reflect the influence of relative immobility. Although plantarflexor muscle overactivity was found to be associated with increased resistance to slow passive stretch, the mechanism was unable to be elucidated from these data. The limb ipsilateral to unilateral neurological impairment cannot be considered to be a 'normal' control for comparative purposes. RELEVANCE: Adaptive shortening and increased resistance to passive lengthening limit active ankle dorsiflexion, and alter ankle biomechanics. Tonic muscle overactivity has the potential to exacerbate these changes. Prophylactic management of inappropriate muscle activity and maintenance of muscle length may facilitate the achievement of rehabilitation goals and reduce subsequent disability following acquired brain injury.     

炎症因子TNF-α/IL-6对透析患者骨骼肌消耗及Myostatin和Atrogin-1表达的影响

目的研究血液透析患者骨骼肌消耗状态与炎症因子水平及肌萎缩基因表达的关系。方法选择维持性血液透析(maintenance hemodialysis,MHD)患者42例(HD组),以30例健康人群为正常对照组(Ctl)。主观全面营养评价法(SGA)法评估患者营养状态,采集人体测量学数据,收集临床生化指标,Elisa方法检测C-反应蛋白(CRP)、白细胞介素-6(interleukin-6,IL-6)、肿瘤坏死因子-α(tumor necrosis factor alpha,TNF-α)等炎症因子水平;留取6位透析患者骨骼肌标本,与4位年龄性别匹配的非肾病者为对照,行HE染色并光镜下观察肌纤维形态,测量和分析肌纤维直径。荧光定量PCR检测肌萎缩标志分子Myostatin、Atrogin-1及炎症因子的转录水平。结果 HD组患者的体质量及体质量指数(BMI)低于健康对照组,其血尿素氮、肌酐和尿酸水平明显升高,并伴轻度贫血,其血清总蛋白和白蛋白、转铁蛋白等营养指标虽然在正常范围,但较对照组明显降低,血脂、血糖与对照组比较无差异;HD组的CRP、TNF-α和IL-6等炎症因子水平显著升高,P0.05;骨骼肌标本光镜下观察到HD组肌纤维形态较纤细、萎缩,肌束间隙较宽,肌纤维直径降低;荧光定量PCR检测结果显示透析患者肌肉组织的myostatin mRNA转录水平上调5.96倍,Atrogin-1 mRNA上调2.43倍;同时TNF-α和IL-6mRNA转录水平分别上调8.37倍和3.36倍。结论血液透析患者骨骼肌消耗性营养不良与炎症因子水平升高相关;肌肉组织的TNF-α、IL-6表达上调,激活myostatin和Atrogin-1的转录,可能是引起骨骼肌消耗的重要机制。     

Velocity dependent passive plantarflexor resistive torque in patients with acquired brain injury

OBJECTIVES: This study sought to determine whether factors other than stretch reflex excitability contribute to velocity dependent passive plantarflexor resistive torque following brain injury. BACKGROUND: In patients with acquired brain injury increased resistance to passive muscle lengthening commonly results from abnormal muscle contraction, secondary to disinhibition of descending motor pathways, in addition to rheologic changes within the musculo-tendinous unit. Hyper-excitable tonic stretch reflex responses (spasticity) have traditionally been considered to be the main factor influencing resistance that is velocity dependent. METHODS: Ten adults with brain injury and eighteen age matched controls were studied. A computer controlled torque measurement system was utilised to evaluate resistance to dorsiflexion stretches at two velocities (5 degrees and 25 degrees s(-1)). Only stretches which did not evoke muscle contraction were included in the data analysis. The mean difference and 95% confidence limits in passive plantarflexor resistive torque at two stretch velocities, measured over a defined portion of the test movement, were compared between subject groups. RESULTS: A velocity dependent increase in passive plantarflexor resistive torque was evident when the ankle was dorsiflexed past the neutral position in both subjects with brain injury and controls. However, the mean difference was approximately 10 times greater in neurologically impaired limbs compared with control values. CONCLUSIONS: These data indicate that an important component of velocity dependent resistance to passive muscle lengthening in adults with brain injury can be mechanical, and unrelated to stretch induced reflex muscle contraction. RELEVANCE: Increased resistive torque during rapid muscle lengthening may represent a compensatory adaptation for reduced distal motor control following brain injury. A velocity dependent increase in passive plantarflexor resistive torque has the potential to improve stability during gait and provide mechanical resistance to sudden external perturbations.     

Comparison of the impact of a single session of isokinetic or isotonic muscle stretch on gait in patients with spastic hemiparesis

OBJECTIVE: To establish if isokinetic and isotonic muscle stretch (with or without weight-bearing) of the ankle plantar flexors improves gait in hemiplegic patients. A further aim was to compare the effectiveness of these treatment methods. DESIGN: A randomized, parallel group prospective study. SETTING: A stroke rehabilitation unit. SUBJECTS: Ambulatory hemiparetic stroke patients with mild to moderately severe muscle hypertonia of the lower limb and a group of healthy control subjects. INTERVENTION: Subjects were randomized to receive a single 20-min session of isokinetic muscle stretch or isotonic muscle stretch with or without weight-bearing. OUTCOME MEASURES: Selected kinematic, kinetic and spatio-temporal gait parameters were measured at baseline, immediately after the muscle stretch and 24 h later. RESULTS: Sixty-six patients and 21 healthy control subjects were recruited and completed the study. There were statistically significant differences between the patient groups and the healthy subjects on most of the gait parameters studied. However, the differences between the patient groups or between the three measurements over time for each type of muscle stretch did not reach statistical significance. CONCLUSIONS: A single session of isokinetic or isotonic muscle stretch (with or without weight-bearing) of the ankle plantar flexors has no clinically observable effect on the gait of hemiplegic stroke patients.     

The effect of prolonged static and cyclic stretching on ankle joint stiffness,torque relaxation,and gait in people with stroke

BACKGROUND AND PURPOSE: Continuous passive motion (cyclic stretching applied to the subject's limb) has been used for the rehabilitation of some orthopedic impairments; however, few researchers have considered its application in the management of neurological disorders such as stroke. The purpose of this study was to examine the short-term effects of prolonged static and cyclic calf stretching on passive ankle joint stiffness, torque relaxation, and gait in people with ischemic stroke. SUBJECTS: Ten community-dwelling people (mean age=64.6 years, SD=8.76, range=53-76) who were diagnosed with a cerebrovascular accident volunteered to be subjects. METHODS: Participants engaged in one 30-minute static stretch and one 30-minute cyclic stretch of the calf muscle, using an isokinetic dynamometer that also collected torque and angle measurements. Before and after treatments, 10-m walking times were collected. Ankle joint stiffness was calculated from the slope of the torque and angle curves before and immediately after treatments, and torque relaxation was calculated as the percentage of decrease in peak passive torque over the 30-minute stretch durations. RESULTS: Ankle joint stiffness decreased by 35% and 30% after the static and cyclic stretches, respectively. Stiffness values and 10-m walk times were not different between conditions. The amount of torque relaxation was 53% greater for static stretching than for cyclic stretching. DISCUSSION AND CONCLUSION: These preliminary data from a very small sample of people with stroke indicate that ankle joint stiffness decreases after both prolonged static and cyclic stretches; however, neither technique appears to be better at reducing stiffness in people with stroke. Torque relaxation is greater after static stretching than after cyclic stretching, and walking speed does not appear to be influenced by the stretching treatments used in our study.     

Action of Obestatin in Skeletal Muscle Repair: Stem Cell Expansion,Muscle Growth,and Microenvironment Remodeling

The development of therapeutic strategies for skeletal muscle diseases, such as physical injuries and myopathies, depends on the knowledge of regulatory signals that control the myogenic process. The obestatin/GPR39 system operates as an autocrine signal in the regulation of skeletal myogenesis. Using a mouse model of skeletal muscle regeneration after injury and several cellular strategies, we explored the potential use of obestatin as a therapeutic agent for the treatment of trauma-induced muscle injuries. Our results evidenced that the overexpression of the preproghrelin, and thus obestatin, and GPR39 in skeletal muscle increased regeneration after muscle injury. More importantly, the intramuscular injection of obestatin significantly enhanced muscle regeneration by simulating satellite stem cell expansion as well as myofiber hypertrophy through a kinase hierarchy. Added to the myogenic action, the obestatin administration resulted in an increased expression of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) and the consequent microvascularization, with no effect on collagen deposition in skeletal muscle. Furthermore, the potential inhibition of myostatin during obestatin treatment might contribute to its myogenic action improving muscle growth and regeneration. Overall, our data demonstrate successful improvement of muscle regeneration, indicating obestatin is a potential therapeutic agent for skeletal muscle injury and would benefit other myopathies related to muscle regeneration.     

体外冲击波通过调控IGF-1和p-AKT水平促进大鼠骨骼肌损伤的修复

目的:探讨体外冲击波通过调控胰岛素样生长因子(IGF)-1和磷酸化蛋白激酶B(p-AKT)的水平促进大鼠骨骼肌钝挫伤后修复的可能作用机制。方法:按随机数字表法将66只雄性成年SD大鼠分为正常组、模型组和治疗组,自制重物打击装置进行骨骼肌钝挫伤造模。正常组大鼠不作任何处理;模型组大鼠造模后不行体外冲击波治疗;治疗组大鼠于...     

Passive stretching does not enhance outcomes in patients with plantarflexion contracture after cast immobilization for ankle fracture: a randomized controlled trial

OBJECTIVE: To compare the efficacy of short- and long-duration passive stretches with a control treatment for the management of plantarflexion contracture after cast immobilization for ankle fracture. DESIGN: Assessor-blinded, randomized controlled trial. SETTING: Hospital physical therapy outpatient departments. PARTICIPANTS: Adults with plantarflexion contracture (N=150) after cast immobilization for ankle fracture. All subjects were weight bearing or partial weight bearing. INTERVENTIONS: Exercise only, exercise plus short-duration passive stretch, and exercise plus long-duration passive stretch. All subjects had a 4-week course of exercises. In addition, subjects in the short-duration stretch plus exercise group completed 6 minutes of stretching per day, and subjects in the long-duration stretch plus exercise group completed 30 minutes of stretching per day. MAIN OUTCOME MEASURES: Lower Extremity Functional Scale and passive dorsiflexion range of motion with the knee bent and straight at baseline, and at 4 weeks and 3 months postintervention. RESULTS: One hundred thirty-nine (93%) subjects completed the 4-week assessment and 134 (89%) subjects completed the 3-month assessment. There were no statistically significant or clinically important between-group differences for the primary outcomes. CONCLUSIONS: The addition of passive stretching confers no benefit over exercise alone for the treatment of plantarflexion contracture after cast immobilization for ankle fracture.     

Slow passive stretch and release characteristics of the calf muscles of older women with limited dorsiflexion range of motion

OBJECTIVE: Examine the slow passive stretch and release characteristics of the calf muscles of older women with limited dorsiflexion range of motion. DESIGN: A cross-sectional comparative design. BACKGROUND: The passive stretch and release characteristics of the calf muscles of older women with limited dorsiflexion range of motion have not been studied. METHODS: Fifteen older women (mean 79 years) with active dorsiflexion < or =10 degrees and 15 younger women (mean 24 years) without limited dorsiflexion were tested. The right ankle was stretched from plantarflexion to maximal dorsiflexion and released into plantarflexion at 5 degrees /s with minimal surface EMG activity in the soleus, gastrocnemius, and tibialis anterior muscles. Length, passive-elastic stiffness and stored passive-elastic energy were examined. RESULTS: The older women had less maximal passive dorsiflexion, a greater initial stretch angle, and less angular change than the younger women (P < 0.05). The maximal passive resistive force (Newtons) of the stretch phase, and the stored passive-elastic energy ( degrees N) during both stretch and release phases were also less (P < 0.001). The older women had greater passive-elastic stiffness at 0 degrees and 5 degrees of dorsiflexion (P < 0.001). CONCLUSIONS: The older women had decreased calf muscle length, extensibility, maximal passive resistive force, stored passive-elastic energy, but greater angle-specific-stiffness at 0 and 5 degrees of passive dorsiflexion. RELEVANCE: Older women with limited dorsiflexion range of motion have decreased calf muscle length, passive resistive forces and stored passive-elastic energy that may impact static and dynamic standing balance activities. Greater passive-elastic stiffness within their ambulatory dorsiflexion range of motion may partially compensate for the deficits.     

耐力训练对大鼠骨骼肌比较基因组学鉴定蛋白-58，脂滴包被蛋白基因表达的影响

摘要 目的：研究不同强度耐力训练对大鼠骨骼肌比较基因组学鉴定蛋白-58(CGI-58)基因和脂滴包被蛋白(perilipin)基因的表达,分析其变化规律,为运动时维持机体能量的动态平衡和代谢健康提供理论依据。 方法：选用SD雄性大鼠48只,随机分为4组,每组12只,即安静对照组（N组）;低强度耐力组（L组）;中等强度耐力组（M组）;大强度耐力组（H组）。运动负荷采用Bedford设定的大鼠运动强度等级,大鼠在跑台上进行不同坡度的递增负荷耐力训练;5周耐力训练结束后,宰杀大鼠。通过逆转录聚合酶链式反应（RT-PCR）测定腓肠肌、比目鱼肌CGI-58基因和perilipin基因表达。 结果：在腓肠肌组织中,CGI-58基因的表达随着运动强度的增加出现上升的趋势,其中在H组CGI-58表达达到最大并且高于U组（P<0.01）,其次是M组和L组。在比目鱼肌组织中,各组大鼠CGI-58基因的表达为：L组、M组和H组的表达都高于N组,其中在M组时表达最强并且高于U组和H组（P<0.05）。在相同训练方式下,H组腓肠肌CGI-58 mRNA表达高于比目鱼肌（P<0.01）。在腓肠肌组织中,perilipin基因的表达随着运动强度的增加出现上升的趋势,在H组表达达到最大并且高于U组和L组（P<0.01）,其次是M组。在比目鱼肌组织中,L组、M组和H组的perilipin基因表达都高于N组,在M组和H组均高于N组（P<0.05）。腓肠肌和比目鱼肌在相同训练方式下,两种肌肉perilipin mRNA表达差异也不明显（P>0.05）。 结论：5周不同强度的耐力训练可以诱发大鼠骨骼肌CGI-58 基因和perilipin基因发生差异表达,表明CGI-58 基因和perilipin基因在不同强度的耐力训练下参与了不同程度的脂肪水解调控。     

Decrease of hypertonia after continuous passive motion treatment in individuals with spinal cord injury

OBJECTIVE: To examine the effect of ankle continuous passive motion on the reflex excitability and overall hypertonia of calf muscles in individuals with chronic spinal cord injury and without physical disabilities. DESIGN: Two-way repeated measure experimental design. SETTING: Inpatient rehabilitation department in general hospital. SUBJECTS: The spinal cord injury group comprised eight individuals with chronic complete spinal cord injury and the control group comprised eight healthy people without physical disabilities. An additional eight healthy people were recruited as the sham group. INTERVENTIONS: Each subject received 60 min of continuous passive motion on the ankle joint. MAIN MEASURES: The H-reflex of the soleus muscle was elicited by tibia nerve stimulation just before, immediately after, and 10 min after continuous passive motion. The Modified Ashworth Scale (MAS) score at the ankle joint was recorded for the spinal cord injury group just before and 10 min after continuous passive motion therapy. RESULTS. After 60 min of continuous passive motion of the ankle joint, the H-reflex amplitude at the soleus muscle was depressed in individuals with and without spinal cord injury (77.46 +/- 32.64%, P = 0.047 and 51.76 +/- 26.74% of initial, P<0.0001, respectively). This depression persisted up to 10 min after continuous passive motion only in individuals without spinal cord injury. In individuals with spinal cord injury, the median of MAS scores decreased from 2 to 1.25 after continuous passive motion. CONCLUSION: Sixty minutes of continuous passive motion of the ankle joint decreased reflex excitability and overall hypertonia in people with or without spinal cord injury. The depression of overall hypertonia persisted longer than the reflex excitability in people with spinal cord injury.     

有氧训练大鼠腓肠肌组织微小RNA-133a和肌细胞增强因子2的表达

背景:研究表明微小RNA-133a、肌细胞增强因子2和成肌分化抗原可调解骨骼肌的分化与重塑。目的:观察有氧训练对腓肠肌微小RNA-133a、肌细胞增强因子2和成肌分化抗原表达的影响。方法:将SD大鼠随机分为对照组和有氧训练组,有氧训练组采用大鼠跑台运动模型,而对照组不进行运动训练。训练4,6周后采集各组大鼠腓肠肌组织,并称取腓肠肌的质量,实时定量PCR检测骨骼肌中肌球蛋白、微小RNA-133a、肌细胞增强因子2与成肌分化抗原mRNA的表达,并采用免疫组织化学的方法检测腓肠肌Ⅱ型肌纤截面积的改变。结果与结论:训练4,6周,有氧训练组大鼠腓肠肌的相对质量以及肌球蛋白重链-Ⅱa的表达水平较对照组显著增加(P<0.05或P<0.01),Ⅱ型肌纤维横截面积即显著增大(P<0.05),其微小RNA-133a和肌细胞增强因子2mRNA的表达较对照组显著升高(P<0.05,P<0.01),而成肌分化抗原mRNA的表达在各组间差异均无显著性意义。证实,有氧训练可上调大鼠腓肠肌组织微小RNA-133a、肌细胞增强因子2mRNA的表达。     

大强度离心运动大鼠不同时相骨骼肌结构及血白细胞介素6、肌酸激酶、肌酸激酶同工酶的变化

背景:运动预处理可在一定程度上减轻运动性骨骼肌微损伤,从而避免延迟性肌肉酸痛的发生.目前应用白细胞介素6和CK-MM评定骨骼肌微细损伤还较缺少实验性研究.目的:观察运动预处理对大鼠大强度离心运动后不同时相骨骼肌结构损伤及血液白细胞介素6、肌酸激酶和CK-MM变化的影响.设计、时间及地点:随机对照动物实验,2006/2007在成都体育学院动物实验室完成.材料:成年健康雌性SD大鼠80只,体质量(231.3±12.44)g.每组义随机分别分为运动前和运动后即刻、运动后24,48,72 h 5个亚组,每组8只.方法:无预处理组:除对运动前组外其他大鼠进行一次速度19～21 m/min,坡度为-16°的90 min的跑台运动.运动预处理组:进行2周离心跑台训练,2周后,除运动前组外,其他大鼠进行一次性跑台运动,运动方式同无预处理组.主要观察指标:一次性离心运动后即刻、24,48和72 h观察比目鱼肌结构及血液白细胞介素6、肌酸激酶、CK-MM的变化.结果:运动后两组大鼠比目鱼肌均出现损伤性改变,尤以无预处理组更为明显,且以运动后24～48 h较为严重.无预处理组运动后即刻血浆白细胞介素6显著增高,随后逐渐下降,72 h再次显著增高.运动预处理组运动后即刻略降低,随后逐渐升高,于48 h达峰值.运动后运动预处理组血浆白细胞介素6水平低于无预处理组.运动前运动预处理组肌酸激酶和CK-MM均低于无预处理组.运动后无预处理组、运动预处理组两组肌酸激酶和CK-MM先升后降,除运动后72 h外.运动预处理组CK和CK-MM水平及变化幅度低于无预处理组.结论:运动预处理有助于减轻离心运动导致的骨骼肌超微结构损伤及运动应激所引起的相关血液指标变化.肌酸激酶和CK-MM活性水平的个体差异较大,更适用于个体自身的纵向比较.     

mdx小鼠骨骼肌组织成肌、成脂、成骨基因的特异性表达

背景：干细胞移植是治疗肌营养不良症的有效方法之一,但移植的干细胞在病理骨骼肌中成肌表达较低。目的：通过比较mdx小鼠和C57小鼠的骨骼肌形态及成肌、成脂、成骨基因表达的差异,探讨mdx小鼠骨骼肌病理改变的可能机制。方法：取mdx小鼠与C57小鼠的骨骼肌组织行冰冻切片,苏木精-伊红染色和Vonkossa染色观察两种小鼠肌肉组织的形态特征;提取mdx小鼠和C57小鼠骨骼肌组织总RNA,real-timePCR检测成肌、成脂、成骨相关基因的表达。结果与结论：mdx小鼠骨骼肌有肌纤维坏死和再生,伴有轻度脂肪、纤维结缔组织增生,Vonkossa染色可见钙结节沉积,而C57小鼠的骨骼肌细胞形态清晰,核位于细胞周边。与C57小鼠比较,mdx小鼠肌肉组织成骨、成脂基因表达有不同程度的上调（P〈0.05）,而成肌基因表达下调（P〈0.05）。dystrophin基因缺失及成肌基因表达下调、成骨和成脂基因上调是造成mdx小鼠肌肉组织变性坏死的原因。     

Decorin gene transfer promotes muscle cell differentiation and muscle regeneration.

We have shown that decorin, a small leucine-rich proteoglycan, can inhibit transforming growth factor (TGF)-beta1 to prevent fibrous scar formation and improve muscle healing after injury. In the decorin-treated muscle, an enhancement of muscle regeneration is observed through histological examination. In this article, we report our determination of whether decorin has a direct effect on myogenic cells' differentiation. Our results indicate that myoblasts genetically engineered to express decorin (CD cells) differentiated into myotubes at a significantly higher rate than did control myoblasts (C2C12). This enhanced differentiation led to the up-regulation of myogenic genes (Myf5, Myf6, MyoD, and myogenin) in CD cells in vitro. We speculate that the higher rate of differentiation exhibited by the CD cells is due to the up-regulation of follistatin, peroxisome-proliferator-activated receptor-gamma co-activator-1alpha (PGC-1alpha), p21, and the myogenic genes, and the down-regulation of TGF-beta1 and myostatin. Decorin gene transfer in vivo promoted skeletal muscle regeneration and accelerated muscle healing after injury. These results suggest that decorin not only prevents fibrosis but also improves muscle regeneration and repair.