Shoulder Muscular Activity During Isometric Three-Point Kneeling Exercise on Stable and Unstable Surfaces

The purpose of this study was to determine if performing isometric 3-point kneeling exercises on a Swiss ball influenced the isometric force output and EMG activities of the shoulder muscles when compared with performing the same exercises on a stable base of support. Twenty healthy adults performed the isometric 3-point kneeling exercises with the hand placed either on a stable surface or on a Swiss ball. Surface EMG was recorded from the posterior deltoid, pectoralis major, biceps brachii, triceps brachii, upper trapezius, and serratus anterior muscles using surface differential electrodes. All EMG data were reported as percentages of the average root mean square (RMS) values obtained in maximum voluntary contractions for each muscle studied. The highest load value was obtained during exercise on a stable surface. A significant increase was observed in the activation of glenohumeral muscles during exercises on a Swiss ball. However, there were no differences in EMG activities of the scapulothoracic muscles. These results suggest that exercises performed on unstable surfaces may provide muscular activity levels similar to those performed on stable surfaces, without the need to apply greater external loads to the musculoskeletal system. Therefore, exercises on unstable surfaces may be useful during the process of tissue regeneration.

Preclinical Studies with Umbilical Cord Mesenchymal Stromal Cells in Different Animal Models for Muscular Dystrophy

Umbilical cord mesenchymal stromal cells (MSC) have been widely investigated for cell-based therapy studies as an alternative source to bone marrow transplantation. Umbilical cord tissue is a rich source of MSCs with potential to derivate at least muscle, cartilage, fat, and bone cells in vitro. The possibility to replace the defective muscle cells using cell therapy is a promising approach for the treatment of progressive muscular dystrophies (PMDs), independently of the specific gene mutation. Therefore, preclinical studies in different models of muscular dystrophies are of utmost importance. The main objective of the present study is to evaluate if umbilical cord MSCs have the potential to reach and differentiate into muscle cells in vivo in two animal models of PMDs. In order to address this question we injected (1) human umbilical cord tissue (hUCT) MSCs into the caudal vein of SJL mice; (2) hUCT and canine umbilical cord vein (cUCV) MSCs intra-arterially in GRMD dogs. Our results here reported support the safety of the procedure and indicate that the injected cells could engraft in the host muscle in both animal models but could not differentiate into muscle cells. These observations may provide important information aiming future therapy for muscular dystrophies.

Imatinib mesylate ameliorates the dystrophic phenotype in exercised mdx mice

Myofiber degeneration, inflammation, and fibrosis are remarkable features of Duchenne muscular dystrophy. We hypothesized that the administration of imatinib mesylate, an inhibitor of tyrosine kinase and TGF-beta pro-fibrogenic activity, could improve the muscular conditions in mdx mice. Four-week old mdx mice were treated and exercised for 6 weeks. Gastrocnemius and diaphragm histopathology, strength, creatine kinase, and cytokine levels were evaluated. The treated group presented increased muscular strength and decreased CK levels, injured myofibers, and inflammatory infiltrates. Pro-inflammatory cytokines and TGF-beta were also reduced, while IL-10 was increased, suggesting an immunomodulatory effect of imatinib, which can ameliorate the dystrophic phenotype in mdx mice. (C) 2009 Elsevier B.V. All rights reserved.

Recessive COL6A2 C-globular Missense Mutations in Ullrich Congenital Muscular Dystrophy ROLE OF THE C2a SPLICE VARIANT

Ullrich congenital muscular dystrophy (UCMD) is a disabling and life-threatening disorder resulting from either recessive or dominant mutations in genes encoding collagen VI. Although the majority of the recessive UCMD cases have frameshift or nonsense mutations in COL6A1, COL6A2, or COL6A3, recessive structural mutations in the COL6A2 C-globular region are emerging also. However, the underlying molecular mechanisms have remained elusive. Here we identified a homozygous COL6A2 E624K mutation (C1 subdomain) and a homozygous COL6A2 R876S mutation (C2 subdomain) in two UCMD patients. The consequences of the mutations were investigated using fibroblasts from patients and cells stably transfected with the mutant constructs. In contrast to expectations based on the clinical severity of these two patients, secretion and assembly of collagen VI were moderately affected by the E624K mutation but severely impaired by the R876S substitution. The E624K substitution altered the electrostatic potential of the region surrounding the metal ion-dependent adhesion site, resulting in a collagen VI network containing thick fibrils and spots with densely packed microfibrils. The R876S mutation prevented the chain from assembling into triple-helical collagen VI molecules. The minute amount of collagen VI secreted by the R876S fibroblasts was solely composed of a faster migrating chain corresponding to the C2a splice variant with an alternative C2 subdomain. In transfected cells, the C2a splice variant was able to assemble into short microfibrils. Together, the results suggest that the C2a splice variant may functionally compensate for the loss of the normal COL6A2 chain when mutations occur in the C2 subdomain.

Effects of Inspiratory Muscle Training on Muscular and Pulmonary Function After Bariatric Surgery in Obese Patients

This study seeks to assess the effect of inspiratory muscle training (IMT) on pulmonary function, respiratory muscle strength, and endurance in morbidly obese patients submitted to bariatric surgery. Thirty patients were randomly assigned to sham muscular training, or to IMT with a threshold device (40% of maximum inspiratory pressure, MIP), for 30 min/day, from the 2nd until 30th postoperative (PO) day. All of them were submitted to a standard respiratory kinesiotherapy and early deambulation protocol. Data on spirometry, maximum static respiratory pressures, and respiratory muscle endurance were collected on the PO days 2, 7, 14, and 30 in a blinded matter. IMT enabled increases in PO MIP and endurance, and an earlier recovery of the spirometry parameters FEV(1), PEF, and FEF(25-75%). Comparing to preoperative values, MIP was increased by 13% at the 30th PO day in the trained group, whereas control group had a reduction of 8%, with higher values for the IMT group (30th PO, IMT-130.6 +/- 22.9 cmH(2)O; controls-112.9 +/- 25.1 cmH(2)O; p < 0.05). Muscular endurance at the 30th PO day was increased in the trained group comparing to preoperative value (61.5 +/- 39.6 s vs 114.9 +/- 55.2 s; p < 0.05), a finding not observed in the control group (81.7 +/- 44.3 vs 95.2 +/- 42.0 s). IMT improves inspiratory muscle strength and endurance and accounts for an earlier recovery of pulmonary airflows in morbidly obese patients submitted to bariatric surgery.

Detection of Spinal Muscular Atrophy Carriers in a Sample of the Brazilian Population

Background: Spinal muscular atrophy is a common autosomal recessive neuromuscular disorder caused by mutations in the SMN1 gene. Identification of spinal muscular atrophy carriers has important implications for individuals with a family history of the disorder and for genetic counseling. The aim of this study was to determine the frequency of carriers in a sample of the nonconsanguineous Brazilian population by denaturing high-performance liquid chromatography (DHPLC). Methods: To validate the method, we initially determined the relative quantification of DHPLC in 28 affected patients (DHPLC values: 0.00) and 65 parents (DHPLC values: 0.49-0.69). Following quantification, we studied 150 unrelated nonconsanguineous healthy individuals from the general population. Results: Four of the 150 healthy individuals tested (with no family history of a neuromuscular disorder) presented a DHPLC value in the range of heterozygous carriers (0.6-0.68). Conclusions: Based on these results, we estimated there is a carrier frequency of 2.7% in the nonconsanguineous Brazilian population, which is very similar to other areas of the world where consanguineous marriage is not common. This should be considered in the process of genetic counseling and risk calculations. Copyright (C) 2011 S. Karger AG, Basel

Neurophysiological findings of the late-onset, dominant, proximal spinal muscular atrophies with dysautonomia because of the VAPB PR056SER mutation

The vesicle-associated membrane protein/synaptobrevin-associated membrane protein B (VAPB) Pro56Ser Mutation has been identified in Brazilian families showing various motor neuron syndromes. However, the neurophysiological characteristics of these patients have not been detailed, and some questions Still need to be solved, such as the possible presence of myotonia and the origin of the abdominal protrusion seen in most patients. The eventual finding of suggestive electrophysiological characteristics would be helpful not only for clinical diagnosis but also to selection of the appropriate DNA test. To clarify these questions we carried out sensory and motor conduction Studies, including symphatetic skin response, and needle examination in six genetically proven affected members. The electromyographic findings were those of a slowly progressive motor neuron disorder. Topographically, the abdominal muscles were severely affected, but the facial and laryngeal muscles were preserved or very mildly involved. Sensory conduction studies and sympathetic Skin responses were normal. No myotonic discharge was recorded. These findings are indistinguishable from those of other motor neuron disorders, although the predominant involvement of the proximal limbs and of the abdominal muscles may be of some help in the appropriate clinical setting.

MITOCHONDRIAL RESPIRATORY CHAIN AND CREATINE KINASE ACTIVITIES IN mdx MOUSE BRAIN

In this study we investigated energy metabolism in the mdx mouse brain. To this end, prefrontal cortex, cerebellum, hippocampus, striatum, and cortex were analyzed. There was a decrease in Complex I but not in Complex 11 activity in all structures. There was an increase in Complex III activity in striatum and a decrease in Complex IV activity in prefrontal cortex and striatum. Mitochondrial creatine kinase activity was increased in hippocampus, prefrontal cortex, cortex, and striatum. Our results indicate that there is energy metabolism dysfunction in the mdx mouse brain. Muscle Nerve 41: 257-260, 2010

Oxidative variables and antioxidant enzymes activities in the mdx mouse brain

Dystrophin is a protein found at the plasmatic membrane in muscle and postsynaptic membrane of some neurons, where it plays an important role on synaptic transmission and plasticity. Its absence is associated with Duchenne`s muscular dystrophy (DMD), in which cognitive impairment is found. Oxidative stress appears to be involved in the physiopathology of DMD and its cognitive dysfunction. In this regard, the present study investigated oxidative parameters (lipid and protein peroxidation) and antioxidant enzymes activities (superoxide dismutase and catalase) in prefrontal cortex, cerebellum, hippocampus, striatum and cortex tissues from male dystrophic mdx and normal C57BL10 mice. We observed (I) reduced lipid peroxidation in striatum and protein peroxidation in cerebellum and prefrontal cortex; (2) increased superoxide dismutase activity in cerebellum, prefrontal cortex, hippocampus and striatum: and (3) reduced catalase activity in striatum. It seems by our results, that the superoxide dismutase antioxidant mechanism is playing a protective role against lipid and protein peroxidation in mdx mouse brain. (C) 2009 Elsevier Ltd. All rights reserved.

Striatum brain-derived neurotrophic factor levels are decreased in dystrophin-deficient mice

Brain dystrophin is enriched in the postsynaptic densities of pyramidal neurons specialized regions of the subsynaptic cytoskeletal network, which are critical for synaptic transmission and plasticity. Lack of dystrophin in brain structures have been involved with impaired cognitive functions. The brain-derived neurotrophic factor (BDNF) is a regulator of neuronal survival, fast synaptic transmission, and activity-dependent synaptic plasticity. The present study investigated BDNF protein levels by Elisa analysis in prefrontal cortex, cerebellum, hippocampus, striatum and cortex tissues from male dystrophic mdx (n = 5) and normal C57BL10 mouse (n = 5). We observed that the mdx mouse display diminution in BDNF levels in striatum (t = 6.073; df = 6; p = 0.001), while a tendency of decrease in BDNF levels was observed in the prefrontal cortex region (t = 1.962; df = 6; p = 0.096). The cerebellum (t = 1.258; df = 7; p = 0.249), hippocampus (t = 0.631; df = 7; p = 0.548) and cortex (t = 0.572; df = 7; p = 0.586) showed no significant alterations as compared to wt mouse. In conclusion, we demonstrate that only striatum decreased BDNF levels compared with wild-type (wt) mouse, differently to the other areas of the brain. This dystrophin deficiency may be affecting BDNF levels in striatum and contributing, in part, in memory storage and restoring. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Transcriptional regulation differs in affected facioscapulohumeral muscular dystrophy patients compared to asymptomatic related carriers

Facioscapulohumeral muscular dystrophy (FSHD) is a progressive muscle disorder that has been associated with a contraction of 3.3-kb repeats on chromosome 4q35. FSHD is characterized by a wide clinical inter- and intrafamilial variability, ranging from wheelchair-bound patients to asymptomatic carriers. Our study is unique in comparing the gene expression profiles from related affected, asymptomatic carrier, and control individuals. Our results suggest that the expression of genes on chromosome 4q is altered in affected and asymptomatic individuals. Remarkably, the changes seen in asymptomatic samples are largely in products of genes encoding several chemokines, whereas the changes seen in affected samples are largely in genes governing the synthesis of GPI-linked proteins and histone acetylation. Besides this, the affected patient and related asymptomatic carrier share the 4qA161 haplotype. Thus, these polymorphisms by themselves do not explain the pathogenicity of the contracted allele. Interestingly, our results also suggest that the miRNAs might mediate the regulatory network in FSHD. Together, our results support the previous evidence that FSHD may be caused by transcriptional dysregulation of multiple genes, in cis and in trans, and suggest some factors potentially important for FSHD pathogenesis. The study of the gene expression profiles from asymptomatic carriers and related affected patients is a unique approach to try to enhance our understanding of the missing link between the contraction in D4Z4 repeats and muscle disease, while minimizing the effects of differences resulting from genetic background.

Reduction of acethylcolinesterase activity in the brain of mdx mice

Lack of dystrophin in brain structures have been involved with impaired cognitive functions. Acethylcolinesterase (AChE) is implicated in many cognitive functions and probably plays important roles in neurodegenerative disorders. In the present study, we investigated AChE activity in the prefrontal cortex, hippocampus, striatum and cortex of mdx mice. To this aim, brain tissues from male dystrophic mdx and normal control mice were used. We observed that mdx mice display a reduction in AChE activity of 40-60% in all brain structures evaluated. In conclusion, dystrophin deficiency may be affecting AChE activity and contributing negatively, in part, to memory storage and restoring. (C) 2011 Elsevier B.V. All rights reserved.

Diagnosis of limb-girdle muscular dystrophy 2A by immunohistochemical techniques

The Western blot technique is currently the standard detection method for suspected limb girdle muscular dystrophy (LGMD) 2A (calpainopathy). This is the first report in the English literature of the successful application of immunohistochemical techniques to support a diagnosis of LGMD 2A. This approach is straightforward and appears to be reasonably specific. We propose that immunohistochemical methods should be re-evaluated for the screening of undiagnosed patients with suspected LGMD 2A.

Animal models for genetic neuromuscular diseases

The neuromuscular disorders are a heterogeneous group of genetic diseases, caused by mutations in genes coding sarcolemmal, sarcomeric, and citosolic muscle proteins. Deficiencies or loss of function of these proteins leads to variable degree of progressive loss of motor ability. Several animal models, manifesting phenotypes observed in neuromuscular diseases, have been identified in nature or generated in laboratory. These models generally present physiological alterations observed in human patients and can be used as important tools for genetic, clinic, and histopathological studies. The mdx mouse is the most widely used animal model for Duchenne muscular dystrophy (DMD). Although it is a good genetic and biochemical model, presenting total deficiency of the protein dystrophin in the muscle, this mouse is not useful for clinical trials because of its very mild phenotype. The canine golden retriever MD model represents a more clinically similar model of DMD due to its larger size and significant muscle weakness. Autosomal recessive limb-girdle MD forms models include the SJL/J mice, which develop a spontaneous myopathy resulting from a mutation in the Dysferlin gene, being a model for LGMD2B. For the human sarcoglycanopahties (SG), the BIO14.6 hamster is the spontaneous animal model for delta-SG deficiency, whereas some canine models with deficiency of SG proteins have also been identified. More recently, using the homologous recombination technique in embryonic stem cell, several mouse models have been developed with null mutations in each one of the four SG genes. All sarcoglycan-null animals display a progressive muscular dystrophy of variable severity and share the property of a significant secondary reduction in the expression of the other members of the sarcoglycan subcomplex and other components of the Dystrophin-glycoprotein complex. Mouse models for congenital MD include the dy/dy (dystrophia-muscularis) mouse and the allelic mutant dy(2J)/dy(2J) mouse, both presenting significant reduction of alpha 2-laminin in the muscle and a severe phenotype. The myodystrophy mouse (Large(myd)) harbors a mutation in the glycosyltransferase Large, which leads to altered glycosylation of alpha-DG, and also a severe phenotype. Other informative models for muscle proteins include the knockout mouse for myostatin, which demonstrated that this protein is a negative regulator of muscle growth. Additionally, the stress syndrome in pigs, caused by mutations in the porcine RYR1 gene, helped to localize the gene causing malignant hypertermia and Central Core myopathy in humans. The study of animal models for genetic diseases, in spite of the existence of differences in some phenotypes, can provide important clues to the understanding of the pathogenesis of these disorders and are also very valuable for testing strategies for therapeutic approaches.