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1
Laws, Nicola. "Characterisation and strategic treatment of dystrophic muscle." University of Southern Queensland, Faculty of Sciences, 2005. http://eprints.usq.edu.au/archive/00001457/.
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The mdx mouse is widely used as a model for Duchenne Muscular Dystrophy, a fatal X-linked disease caused by a deficiency of the sub-sarcolemmal protein, dystrophin. This dissertation reports characterisation of the features of dystrophy in the mdx mouse, including parameters such as electrophysiological and contractile properties of dystrophic cardiac tissue, quantitative evaluation of kyphosis throughout the mdx lifespan, and contractile properties of respiratory and paraspinal muscles. Following these characterisation studies, the efficacy of antisense oligonucleotides (AOs) to induce alternative mRNA splicing in mdx skeletal muscles (diaphragm and paraspinal muscles) was evaluated. The left atria of younger (<6 weeks) and older (>15 months) mdx mice showed consistently lower basal forces and responsiveness to increased calcium, while action potential duration was significantly shorter in young mice (3 weeks) and older mice (9 and 12 months) (P<0.05). Cardiac fibrosis increased with age in mdx atria and ventricles and was elevated in young (6-8 weeks) and old (15 months) mdx compared to control mice (P<0.01). This study provided insights into DMD cardiomyopathy, and suggested that very young or old mdx mice provide the most useful models. Mdx mice show thoracolumbar kyphosis like boys with Duchenne Muscular Dystrophy. A novel radiographic index, the Kyphotic Index (KI), was developed and showed that mdx mice are significantly more kyphotic from 9 months of age, an effect maintained until 17 months (P<0.05). At 17 months, the paraspinal and respiratory muscles (latissimus dorsi, diaphragm and intercostal muscles) are significantly weaker and more fibrotic (P<0.05). Administration of AOs at four sites within the diaphragm at 4 and 5 months of age significantly increased twitch and tetanic forces compared to sham treated mdx (P<0.05). However, no difference in collagen was evident and dystrophin was not detected, possibly due to the low concentration of AO utilised. This study suggested that AOs can provide functional improvement in treated skeletal muscles. Monthly injections with AOs into the paraspinal muscles from 2 months to 18 months of age alleviated kyphosis, without significantly altering twitch and tetanic forces of latissimus dorsi, diaphragm and intercostal muscles. There was evidence of less fibrosis in diaphragm and latissimus dorsi muscles (P<0.05) and reduced central nucleation of the latissimus dorsi and intercostal muscles (P<0.05). Again, dystrophin was not detected by immunoblot. These studies indicate that very young and old mdx mice display previously uncharacterised dystrophic features, and are useful models for testing new therapies such as AOs. Low doses of AOs were shown to be safe and efficacious for long-term use, however there remains a need for testing higher concentrations and improved delivery strategies.
2
Wolff, Andrew. "Mechanical Properties of Maturing Dystrophic Skeletal Muscle." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/37922.
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The main goal for my research was to challenge the long held belief that the mechanical properties of maturing dystrophic compared to control skeletal muscle membranes are weaker, leading to onset of Duchenne muscular dystrophy (DMD). We built on a previous report from our lab that suggested sarcolemmal membranes from dystrophic mice are not more susceptible to damage early in maturation (i.e., age 9-12 days) and determined if and when muscle mechanical properties change as the mice mature. Across four studies, I have helped define the role of dystrophin-deficient skeletal muscle membranes in the onset of DMD.
A linear viscoelastic muscle model was used to determine passive stiffness and damping in control and dystrophic muscles from maturing mice aged 14-35 days. Results confirmed my hypothesis that there are no differences in passive mechanical properties between normal and dystrophic mice.
Recognizing the limitations of the linear model, a nonlinear model was developed to determine the stiffness and damping of active and passive dystrophic muscles from maturing mice aged 21 and 35 days. The nonlinear model achieved a significantly better fit to experimental data than the linear model when muscles were stretched to 15% strain beyond resting length. Active and passive mechanical properties of dystrophic mice were not different than control at 14 and 28 days of age.
The previously developed nonlinear model was used to determine a more complete time-course (14-100 days of age) of dystrophic muscle mechanical properties. There was no difference in passive stiffness between mdx and control muscles at each age. However, the mdx:utrn-/- muscles showed increased stiffness compared to control and mdx muscles at 21 and 28 days, suggesting a temporary change within the muscle that only occurs with a lack of both utrophin and dystrophin.
Fast-twitch and slow-twitch muscle mechanical properties were compared in control and dystrophic mice aged 3, 5, and 9 weeks of age. Dystrophic and control slow-twitch muscles did not have different mechanical properties, suggesting that a lack of dystrophin does not affect slow-twitch muscles during maturation (3-5 weeks) or well after maturation (9 weeks).<br>Ph. D.
3
Morrison, Jamie Ian. "Factors affecting excessive collagen production in dystrophic muscle." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/7695.
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Dutton, Anna Louise. "An investigation into the effects of dystrophin on the lateral mobility of muscle membrane components." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4576/.
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Dystrophin is the product of the Duchenne Muscular Dystrophy gene locus, whose absence results in progressive skeletal muscle breakdown. Despite considerable work on the localisation of dystrophin and its associated complex, its role in muscle function remains unclear. In the light of the structural and mechanical instability of the dystrophic membrane, the idea was tested that dystrophin might impart membrane integrity and strength by anchoring membrane proteins and/or delineating the surface into specialised subcellular functional domains. Specifically, because dystrophin shows high sequence, structural and spatial similarities to the cytoskeletal protein spectrin; and because spectrin is proven to sterically restrict protein lateral diffusion through a subplasmalemmal network; the capacity of dystrophin to act as a 'molecular fence' to membrane diffusion was studied by comparing lateral mobility of membrane glycoproteins by fluorescence photobleach recovery in mdx and normal tissue. Secondly, as dystrophin has been proven to interact directly with proteins of the dystrophin associated glycoprotein complex in vivo, experiments addressed whether specific binding and immobilisation of the complex by dystrophin at the membrane was essential for function. Finally, given the homology of dystrophin and spectrin, the presence of dystrophin at the neuromuscular junction, and the importance of spectrins in immobilisation of voltage gated sodium channels in the nervous system, the role of dystrophin in regulating voltage gated sodium channel distribution at the neuromuscular junction was investigated. The results show that membrane glycoproteins were immobile in the presence and absence of dystrophin, suggesting dystrophin is not an essential molecular fence component. Alternatively, viability may have been the major influence on protein and lipid diffusion in these fibres and suggestions are made as to how this may be recognised and overcome for subsequent investigation. Three novel exon specific anti-dystrophin peptide antibodies were generated during the work that will be useful for studies into Duchenne muscular dystrophy in general, and dystrophin revertant fibres in particular.
5
Rowe, K. A. "Quantitative microscopic studies of normal and dystrophic chicken muscle." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375318.
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Bryers, P. S. "Regeneration and differentiation of muscle from normal and dystrophic mice." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374843.
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Draper, Kati Elizabeth. "Increased structure-bound proteolytic activity in maturing dystrophic skeletal muscle." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31735.
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Duchenne Muscular Dystrophy (DMD) is a severe X-linked progressive muscle wasting disease resulting from the absence of the membrane-associated protein dystrophin and the secondary components of the dystrophin-glycoprotein complex. Although the genetic basis of the disease has been known for over 15 years, the onset mechanism of the disease is not yet known and no treatment is yet available to significantly increase the lifespan of DMD patients.
Increased levels of intracellular calcium have been noted in dystrophic muscle (Turner et al., 1991) and increased intracellular levels of calcium in skeletal muscle lead to increased levels of calcium-dependent proteolysis (Zeman et al., 1985). Increased levels of calpain, a calcium-dependent protease have been reported as early as age 4 weeks in mdx (dystrophin-deficient) mice (Spencer et al., 1995). Increased calpain activity has been demonstrated in mdx myotubes (Alderton et al., 2000a). There is also evidence of a role for calpain in DMD, but the contribution of calpain activity to the onset of DMD has not yet been determined.
The purpose of this study was to test the hypothesis that increased calpain activity contributes to the onset of DMD in maturing (birth to weaning) dystrophic skeletal muscles and to determine if increased calpain activity was due to the relative distribution of calpain and calpastatin, calpainâ s endogenous inhibitor. Calpain activity was assessed in quadriceps and diaphragm muscle homogenate supernatant and pellet fractions from C57BL/6 control and mdx mice at ages 7, 14, and 21 days. Total calpain and calpastatin content were determined by Western analysis.
In both the quadriceps and diaphragm samples, calpain activity in the supernatant increased with age. There was a significant increase (47.7%; p<0.05) in calciumdependent calpain activity in mdx quadriceps pellet compared to control at age 7 days. In the quadriceps at age 7 days, calpain activity in the pellet in the presence of calcium was significantly greater than at age 14 (61.2%) and 21 days (52.6%; p<0.05). In the diaphragm, there were no significant differences in pellet activity in either the presence or absence of calcium at any age between control and mdx samples. In both control and mdx diaphragms, pellet calpain activity in the absence compared with the presence of calcium was significantly greater at both age 7 (control, 46.4%; mdx, 45.4%) and 14 days (control, 42.4%; mdx, 43.6%; p<0.05). At age 21 days, both control and mdx calpain activities in the diaphragm supernatants in the presence of calcium were significantly greater than those at ages 7 (control, 66.7%; mdx, 72.1%) and 14 days (control, 39.9%; mdx 49.5%; p<0.05). In general, there were no differences in total calpain and calpastatin content that would account for the differences in calpain activity. There were similar patterns of calpain activity and total calpain and calpastatin content in both control and mdx samples, suggesting a similar pattern of development in control and mdx muscle from ages 7-21 days. The increase in calcium-dependent calpain activity in mdx quadriceps pellet compared to control at age 7 days may be due to differences in regulation and/or distribution of the calpain system early in mdx maturation compared to control. From the present study, the role of calpain in the onset of DMD appears to be minor if global calcium-dependent activity is evaluated.<br>Master of Science
8
Veal, Elizabeth Ann. "The role of proto-oncogenes in normal and dystrophic skeletal muscle." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307666.
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Jarvis, Jonathan Charles. "The effects of electrical stimulation on normal and dystrophic avian muscle." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46382.
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Wang, Qiong. "The activity and content of calpains in maturing dystrophic muscle membranes." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/42729.
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Increased calcium-activated calpain proteolysis in the sarcolemma membrane is thought to be a primary mechanism in the pathophysiology of Duchenne Muscular Dystrophy (DMD). However, few studies have tested this possibility prior to the overt signs of the dystrophy. The purpose of this study was to test the hypothesis that there is greater calpain content and total relative calpain activity in membranes obtained from dystrophic (mdx; mdx:utrophin-deficient (mdx:utrn-/-)) compared to wildtype (wt) mouse skeletal muscles during maturation at ages 7- and 21-d,and at a post-maturation age of 35-d. Calpain activity was determined as the calcium-dependent cleavage of the flurogenic substrate SLY-AMC, and content was determined by Western analysis with an anti-calpain antibody. There were several intriguing findings:
1. There was an inverse relationship between calpain content and relative activity in the whole muscle in both wt and mdx mice from age 7- to 35-d: calpain content decreased, and relative calpain activity increased as the mice aged. This suggests a similar role for calpain in both genotypes, which might relate to specific maturation processes, possibly up to age 21-d. Although the inverse relation was evident at 35-d, the targets for calpain in mdx compared to wt likely differed.
2. The increased relative calpain activity in the membrane fraction of mdx mice at age 35-d (26.73 Arbitrary Units, (AU)) compared to that of age 7- (4.9AU; p<0.05) and 21-d (8.74AU; p<0.05) is temporally related to degeneration and regeneration processes, and may also indicate activation of apoptosis, in mdx muscles at this age.
3. At age 7-d, there were no significant differences in either calpain content or relative calpain activity in all subcellular fractions for wt and mdx mice. This result might suggest similar calpain distribution and activities that are related to the regulation of muscle maturation and differentiation in both genotypes. (Note:data were not obtained for the mdx:utrn-/- mice at age 7-d because of insufficient animals).
4. At age 21-d, there was greater relative calpain activity in the myofibrillar supernatant fraction in mdx (15.13AU) than wt mice (1.18AU; p<0.05). This could indicate calpainâ s role in the initiation of myofibrillar protein turnover and the proteolysis of submembranous networks in the mdx muscles.
5. At age 21-d, greater calpain content in the mdx (1.40ìg) compared to wt (0.23 ìg; p<0.05) membrane fraction might suggest a broader distribution of calpain along membranes that contributes to the onset of dystrophy in the mdx muscles.
6. At age 35-d, there was greater calpain content in the mdx:utrn-/- compared to the wt membrane (0.48ìg vs 0.13 ìg), cytosolic (0.88ìg vs 0.30ìg), and myofibrillar supernatant (0.49ìg vs 0.17ìg; p<0.05 ) fractions This increased content and broad distribution across several subcellular fractions may reflect degeneration and regeneration processes, and potentially activation of apoptosis, in the mdx:utrn-/- muscles.
These data suggest that calpain activity contributes to dystrophic pathophysiology mainly in the membrane fraction of mdx skeletal muscles at age ~21-d, but appears to contribute later at 35-d and in more subcellular fractions in mdx:utrn-/- skeletal muscles.<br>Master of Science
11
van, Erp Christel. "Modifying function and fibrosis of cardiac and skeletal muscle from mdx mice." University of Southern Queensland, Faculty of Sciences, 2005. http://eprints.usq.edu.au/archive/00001521/.
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Duchenne Muscular Dystrophy (DMD) is a fatal condition occurring in approximately 1 in 3500 male births and is due to the lack of a protein called dystrophin. Initially DMD was considered a skeletal myopathy, but the pathology and consequences of cardiomyopathy are being increasingly recognised. Fibrosis, resulting from continual cycles of degeneration of the muscle tissues followed by inadequate regeneration of the muscles, is progressive in both cardiac and skeletal dystrophic muscle. In the heart fibrosis interferes with contractility and rhythm whereas it affects contractile function and causes contractures in skeletal muscles. This study utilised the mdx mouse which exhibits a pathological loss of muscle fibres and fibrosis characteristic of DMD, to examine a range of mechanisms that can influence muscle function and fibrosis. Ageing and workload both appear to contribute to the development of dystrophic features in cardiac and skeletal muscle of the mdx mouse. Therefore the effect of eccentric exercise on cardiac and skeletal muscle was examined in older mdx mice. Mice ran in 30 minute sessions for five months, 5 days per week. Downhill treadmill running did not exacerbate the contractile function or fibrosis of the mdx heart or the EDL, SOL or diaphragm muscles suggesting that cytokines influence function and fibrosis to a greater extent than workload alone. The role of the cytokine TGF-beta was examined by treating mdx mice with the TGF-beta antagonist pirfenidone at 0.4, 0.8 or 1.2 per cent in drinking water for six months. Pirfenidone improved cardiac contractility (P<0.01) and coronary flow (P<0.05), to levels comparable to control mice, despite no reduction in cardiac fibrosis. Pirfenidone did not reduce fibrosis or improve function in skeletal muscle. A deficiency of neuronal nitric oxide synthase (nNOS) in DMD and mdx mice causes a lowered production of nitric oxide indicating that the substrate of nNOS, l-arginine, may be beneficial to cardiac and skeletal muscle function in mdx mice. Oral l-arginine (5 mg/g bw) improved cardiac contractility, coronary flow and reduced cardiac fibrosis (P<0.05) without improving skeletal muscle function or fibrosis. In contrast, 10 mg/g bw l-arginine improved cardiac function and coronary flow (P<0.01), despite also elevating cardiac collagen. This increment in collagen was prevented by co-administration of prednisone. The experiments described in this dissertation reveal for the first time that pharmacological treatments in mdx mice can improve cardiac structure and function. Further elucidation of the optimum time and doses of such treatments may result in future pharmacological treatments to improve cardiac function and fibrosis in DMD.
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Turner, Sally Ann. "Analysis of dystrophic mdx muscle following the implantation of normal dermal fibroblasts." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271623.
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Fisher, Ivan Brian. "Glucocorticoid-induced changes in the skeletal muscle of the dystrophic MDX mouse." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407223.
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Coenen-Stass, Anna. "Investigation of extracellular microRNAs and Serum Protein Biomarkers in dystrophic Muscle Disease." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:66d50b2b-b8b5-4604-a8ef-6b08de3d06b6.
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Gerhalter, Teresa. "Characterization of the dystrophic muscle by ²³Na NMR and ¹H NMR T₂ spectrum." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS219/document.
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Le but de la thèse était d'étudier la sensibilité de nouveaux biomarqueurs RMN visant à quantifier les changements pathologiques dans le muscle dystrophique. La dystrophie musculaire (DM) désigne un groupe hétérogène de maladies avec une atrophie musculaire progressive associée à un état de faiblesse. Elle est caractérisée par des degrés variables de nécrose, de régénération, de troubles de l'homéostasie ionique, d'inflammation chronique et finalement par le remplacement des muscles par du tissu fibro-graisseux. Mon objectif était d’évaluer la RMN du ²³Na et les techniques avancées de mesure du temps de relaxation transversal ¹H (T₂) en tant que des biomarqueurs sensibles et précoces. La RMN du ²³Na mesure les concentrations de sodium étroitement contrôlées et donne sa distribution dans le tissu. Cette information peut être utilisée pour évaluer l'homéostasie ionique et l'intégrité cellulaire. Cependant, la concentration in vivo en ²³Na est faible, la RMN du ²³Na souffre donc d'une faible sensibilité par rapport à ¹H. L’altération du T₂ ¹H du muscle, communément interprétée comme un indicateur de l'activité de la maladie, est liée à une variété d’événements non-spécifiques tels que l'œdème, l'inflammation ou la nécrose, qui précèdent le remplacement musculaire par la graisse. Des protocoles comprenant diverses méthodes de RMN du ²³Na et de ¹H T₂ ont été mis en œuvre pour évaluer les tissus musculaires squelettiques sains et dystrophiques sur des modèles animaux et sur patients. Ce travail fournit des preuves que la RMN du ²³Na pourrait offrir un biomarqueur sensible capable de surveiller l'altération spécifique du muscle dystrophique à un stade très précoce<br>The aim of the thesis is to investigate the sensitivity of novel NMR outcome measures (OM) aiming to quantify pathological changes in the dystrophic muscle. Muscular dystrophy (MD) refers to a heterogeneous group of diseases with progressive muscle wasting and associated weakness characterized by variable degrees of necrosis, regeneration, ionic homeostasis disturbances, chronic inflammation, and, ultimately, resulting in the replacement of muscles by fibro-fatty tissue. My focus was on the evaluation of ²³Na NMR and advanced ¹H transverse relaxation time (T₂) techniques as early, sensitive OM. ²³Na NMR measures the tightly controlled sodium concentrations and distribution in skeletal muscle tissue. This biophysical information can be used to assess ion homeostasis and cell integrity. However, ²³Na NMR suffers from a low sensitivity and in vivo concentration compared to ¹H. Alterations in the muscle ¹H T₂, commonly interpreted as an indicator of disease activity, are linked to a variety of non-specific events like oedema, inflammation, or necrosis that precede the actual muscle replacement by fat. Protocols including different ²³Na NMR and ¹H T₂ methods were implemented to evaluate healthy and dystrophic skeletal muscle tissues of animal models and patients. This work provides evidence that ²³Na NMR could offer a sensitive outcome measure able to monitor specific alteration of the dystrophic muscle at a very early stage
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Johnson, Marjorie Isabelle. "Alterations in fast and slow-twitch muscles of genetically dystrophic mice with special reference to parvalbumin." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27358.
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Muscular dystrophy is a genetic disease which affects the morphology, physiology and biochemical nature of the muscle fiber. This study was designed to examine the progressive effects of muscular dystrophy on the differentiation process of skeletal muscle. Chapter 1 examines the neonatal development of muscle spindles and their intrafusal fibers in the soleus and extensor digitorum longus (EDL) of genetically dystrophic mice according to histochemical, quantitative, and ultrastructural parameters. Despite alterations in the surrounding extrafusal fibers, muscle spindles and their intrafusal fibers appeared enzymatically and histologically unaffected in incipient stages of murine dystrophy.
In the second chapter the distribution and concentration of parvalbumin (PV), a calcium-binding protein, in 32 and 2-week-old dystrophic mice was mapped by immunohistochemical and biochemical procedures. The number of parvalbumin-immunoreactive fibers was significantly reduced in the adult dystrophic EDL but slightly increased in the adult dystrophic soleus. No differences between strains were observed in the 2-week samples. These findings were supported by routine myosin ATPase histochemistry. Parvalbumin was isolated on SDS-PAGE gels and the concentration of PV was estimated by a RIA. These results confirmed the immunohistochemical data in that PV content was dramatically reduced in the adult dystrophic EDL and significantly increased in the dystrophic soleus. No changes were detected in the samples of the 2-week-old muscles. The similarity in the distribution and content of PV between the fast and slow dystrophic muscles at 32 weeks of age suggests an alteration in the distribution and phenotypic expression of fiber types in muscular dystrophy and supports the hypothesis that dystrophy alters the normal differentiation process of skeletal muscle.<br>Medicine, Faculty of<br>Cellular and Physiological Sciences, Department of<br>Graduate
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Joseph, Sarah. "The potential role of toll-like receptor 2 in dystrophic- deficient skeletal muscle." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86855.
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The mdx mouse is the genetic homologue of Duchenne Muscular Dystrophy (DMD). In this model, repeated cycles of muscle fiber necrosis occur within the diaphragm and other muscles. It has been reported that molecules associated with tissue damage, such as extracellular matrix breakdown products, can act as endogenous ligands for Toll-Like receptors (TLRs). However, the role of TLRs and endogenous ligands released from damaged skeletal muscle has not been examined. The goals of this study were to determine whether genes associated with TLR function are abnormally regulated in mdx diaphragm and tibialis anterior and if TLR2 gene ablation affects genes associated with TLR signaling and inflammation. By quantitative RT-PCR, multiple genes associated with TLR signaling and inflammation were significantly upregulated in the mdx diaphragm and tibialis anterior muscles. Genetic ablation of TLR2 in mdx mice was associated with a significant downregulation of many pro-inflammatory genes. Our findings suggest that genes of the TLR signaling pathway are upregulated in mdx skeletal muscles and are linked to excessive inflammation.<br>Dans le modèle murin, mdx , de la Dystrophie Musculaire de Duchenne, des cycles répétés de nécrose des fibres musculaires se produisent dans le diaphragme ainsi que d'autres muscles. Il a été montré que des molécules associées au dommage tissulaire, telles que des produits issus de la dégradation de la matrice extracellulaire peuvent agir comme ligands des récepteurs Toll (TLRs). Cependant, le rôle des TLRs dans la pathologie du muscle dystrophique ainsi que leur capacité à interagir avec des ligands endogènes libérés lors de dommage du muscle squelettique n'ont jamais été étudiés. Le but de cette étude est de déterminer: 1) d'une part si les gènes associés à la signalisation des TLRs sont élèvés et d'autre part si l'extinction du gène TLR2 dans les souris mdx affecte les gènes associés à la signalisation des TLRs et à l'inflammation. Par RT-PCR quantitative, nous avons montré que de multiples gènes associés à la fonction TLRs étaient régulés positivement à la fois dans le diaphragme et le muscle Tibialis Anterior mdx. L'extinction du récepteur TLR2 dans les souris mdx a provoqué une significative regulation negative de nombreux gènes pro-inflammatoires.
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Marrone, Anna Filomena. "Retinoblastoma (Rb) regulation and programmed cell death (PCD) in dystrophic (mdx) skeletal muscle." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621356.
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Doreste, Gonzalez Bruno. "The effect of modulating the dystrophic skeletal muscle environment on satellite cell engraftment." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10051216/.
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Satellite cells derived from normal donor mice contribute to muscle regeneration and restore dystrophin expression when transplanted into dystrophin-deficient mice (mdxnu/nu). However, unless the local host muscle environment has been modulated with high doses of gamma-radiation to incapacitate host satellite cells, but maintaining a functional niche, donor satellite cell engraftment is negligible. This work aimed to determine the cells and pathway(s) within host muscle which are responsible for mediating the radiation-induced effect. I first investigated whether this effect was mediated by apoptotic cells, by quantifying the percentage of TUNEL positive cells in muscles at basal levels and at different time points after irradiation. There was a correlation between the percentage of TUNEL positive cells and the time for optimal engraftment in mdxnu/nu host muscles. This suggests that apoptotic cells within host muscle might be mediators of the radiation-induced promotion of donor satellite cell engraftment. Then I performed a series of co-transplantation experiments to determine whether different cell preparations within the pre-irradiated mdxnu/nu muscle would enhance donor satellite cell transplantation. Three cell preparations (satellite cells, monocytic cell suspension, and single myofibres) were isolated from pre-irradiated mdxnu/nu donors and grafted with donor 3F-nLacZ-2E satellite cells into mdxnu/nu hosts. None of these preparations significantly enhanced donor satellite cell engraftment in non-irradiated hosts. Finally, I performed RNA sequencing on differentially treated muscles to investigate possible signalling pathways involved in enhancing satellite cell engraftment in pre-irradiated muscles. This revealed a phenotype consistent with type I and type II interferon responses after irradiation, leading to the secretion of the IL-6 family of cytokines. Further investigation confirmed an upregulation of LIF in pre-irradiated muscle. Overall, my findings suggest that irradiation of host muscle alters the inflammatory phenotype and elicits the secretion of the IL-6 family of cytokines, which are powerful regulators of satellite cell proliferation and differentiation.
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Rittler, Matthew Robert. "Sarcoplasmic Reticulum Calcium Handling in Maturing Skeletal Muscle From Two Models of Dystrophic Mice." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35619.
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<p>Duchenne's muscular dystrophy (DMD) is a debilitating disease that affects approximately 1 in 3500 boys, with many DMD patients dying before the age of 20 due to cardio-respiratory complications. DMD is the result of defects in the gene that encodes dystrophin, an integral muscle membrane protein. Although the genetic defect has been identified, the relation between the absence of expressed dystrophin and the mechanisms leading to its onset are still unclear. One possibility is that disrupted calcium (Ca<sup>2+</sup>) handling by the sarcoplasmic reticulum (SR) leads to an increased cytosolic Ca<sup>2+</sup> concentration that activates proteolytic and apoptotic pathways that initiate muscle fiber death. However, little is known about the role of disrupted SR function in the onset of DMD. </p><p>
The purpose of this study was to test the hypothesis that altered calcium cycling by the SR could contribute to elevated cytosolic Ca<sup>2+</sup> levels in the early stages of DMD, and thereby account for the onset of disease pathogenesis. Rates of SR Ca<sup>2+</sup> uptake and release were determined in quadriceps muscles obtained from maturing dystrophic and control mice prior to the overt signs of the disease at ages ~9 and 21 days. In addition, the content of several key Ca<sup>2+</sup> handling proteins, including two isoforms of the sarco(endo)plasmic reticulum ATPase pump (SERCA 1 & 2), ryanodine receptor type 1 (RyR1), parvalbumin, and calsequestrin were determined by Western analysis. Two dystrophic mouse models were used, the mdx mouse which lacks dystrophin, and the mdx:utrophin-deficient (mdx:utrn<sup>-/-</sup>) mouse which also lacks utrophin, a protein homolog of dystrophin. </p><p>
The rate of SR Ca<sup>2+</sup> uptake in quadriceps muscles of mdx/utrn<sup>-/-</sup> mice aged 21 days was 73.1% and 61.3% higher than age-matched control and mdx muscles, respectively (p < 0.05). There was no difference in SR Ca<sup>2+</sup> release rates between the genotypes at either age. There were significant increases in the content of each of the calcium handling proteins with age (p < 0.05), but no significant differences were detected between genotypes at either age. These data demonstrate the Ca<sup>2+</sup> release rates of dystrophic SR are not compromised, but suggest the increased uptake rates of mdx:utrn<sup>-/-</sup> SR may be an adaptation to increased cytosolic calcium levels, and/or be due to changes in intrinsic SERCA function and/or regulation. The role of increased SR Ca<sup>2+</sup> uptakes rates in onset of DMD pathogenesis can not be directly determined from the present data; therefore it is suggested that future studies directly assess cytosolic Ca<sup>2+</sup> concentration and examine the role of SERCA regulatory proteins in intact fibers obtained from mdx:utrn<sup>-/-</sup> muscles at age 21 days. </p><br>Master of Science
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Russell, Paul. "Membrane properties and calcium ion activity in skeletal muscle fibres of the dystrophic mouse." Thesis, University of Central Lancashire, 1993. http://clok.uclan.ac.uk/20630/.
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The ReJI29 murine model of muscular dystrophy was employed to investigate the properties of skeletal muscle plasmalemma and calcium ion movements during muscle wastage, with the intention of determining the route of calcium influx, and the efficacy of calcium ion blockers in preventing this influx. Electrophysiological parameters (Resting membrane potential [RMP] and input resistance) reached adult magnitude in normal soleus and extensor digitorum longus (EDL) by 4 weeks and 3 weeks respectively. Electrophysiological parameters in dystrophic soleus developed in a similar maimer to normal muscle, but RMP in dystrophic EDL was reduced and input resistance was elevated suggesting the presence of a population of regenerating fibres. Twitch and contracture tension development reached mature levels by 4 weeks in normal soleus muscle, but development was prolonged to 10 weeks in EDL, due to the slower development of type II fibres. Contracture tension was markedly smaller in EDL possibly due to fibre type-related differences in the concentrations of calcium sequestering proteins. Twitch and contracture tension in dystrophic soleus was identical to normal. In dystrophic EDL, 4 week old muscle did not generate tension from either electrical or chemical stimulation. Older muscles generated tension but smaller than their normal counterparts. Twitch and contracture tomography revealed similarities between dystrophic EDL and immature normal EDL corroborating with the conclusions made from the electrophysiological experiments. Caffeine contractures generated in glycinerated normal soleus muscle, incubated in low calcium saline, and then bathed in high calcium saline reached 115-185% the magnitude of caffeine contractures generated prior to incubation. 4 week dystrophic soleus attained similar sized contractures, but contractures were reduced to 77-90% in older muscles. This technique was found to be inappropriate in the study of EDL. Caffeine contractures generated by normal soleus in normal saline, after incubation in low calcium saline, reached the magnitude of contractures generated in high calcium saline after 30 minutes. Contractures generated by dystrophic soleus remained identical to those generated in high calcium saline suggesting that the sarcoplasmic reticulum in these fibres was unable to cope with a high calcium load. This result gave the first indication that soleus muscle was affected by muscular dystrophy. Membrane bound calcium derived from 45Calcium influx studies was 2nmoles/mg tissue/30 minutes in soleus and 1 Snmoles/mg tissue weight/30 minutes in EDL. Intracellular influx was 0.5-0.6nmoles/mg tissue weight/ 30 minutes in both muscles. Membrane bound calcium was elevated in dystrophic EDL to 2.5-3.8nmoles/mg tissue weight/30 minutes, but influx was normal in both dystrophic soleus and EDL, casting doubt on whether the plasmalemma is more permeable to calcium. The increase in membrane bound calcium may be artefactual. Cadmium blocked influx in both normal and dystrophic muscles. Blot weights showed continual growth in normal muscles although the rate decreased after 10 weeks. In dystrophic muscles growth ceased after 10 weeks. NCP data was limited but did show a decrease in dystrophic muscle, followed by an increase. Tension as a function of tissue mass, revealed that the contractile apparatus in normal soleus matured within 2 weeks, and by 10 weeks in EDL due to the differences in myosin isoforms present in each fibre type. These ratios were elevated in dystrophic muscle indicating calcium accumulation in the sarcoplasmic reticulum. The results showed that EDL muscle was more severely affected by muscular dystrophy. Between 2 and 4 weeks, the muscle underwent degeneration via an unidentified process. There was regeneration, and the regenerating fibres appeared to be normal. Soleus muscle appeared resistant to the disease but succumbed under unusual chemical stresses. Some aspects of development of normal muscle were also considered.
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Penton, Christopher. "In Vitro Differentiation of Muscle Side Population Cells from Dystrophic Muscle Reveals Absence of Myogenesis and Implications for Hedgehog Signaling." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385397533.
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Al-Rewashdy, Hasanen. "Determining the Contribution of Utrophin A Versus Other Components of the Slow, Oxidative Phenotype in the Beneficial Adaptations of Dystrophic Muscle Fibers Following AMPK Activation." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31470.
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Duchenne Muscular Dystrophy (DMD) results from the absence of a functional dystrophin protein. Among its possible therapeutic options is the upregulation of dystrophin’s autosomal analogue, utrophin A. This can be achieved by a pharmacologically induced shift towards a slower, more oxidative skeletal muscle phenotype, which has been shown to confer morphological and functional improvements on models of DMD. Whether these improvements are a result of the utrophin A upregulation or other beneficial adaptations associated with the slow, oxidative phenotype, such as improved autophagy, has not been determined. To understand the importance of utrophin A to the therapeutic value of the slow, oxidative phenotype, we used the utrophin/dystrophin double knockout (dKO) model of DMD. We found the dKO mouse to have a similar skeletal muscle signaling capacity and phenotype to mdx mice. When treated with the adenosine monophosphate activated protein kinase (AMPK) agonist 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), both dKO and mdx mice expressed a shift towards a slower, more oxidative phenotype. In the mdx mice, this shift caused improvements in muscle fiber central nucleation, IgM penetration, damage from eccentric contractions, and forelimb grip strength. These morphological and functional benefits were not seen in the AICAR treated dKO mice. This study highlights the importance of utrophin A upregulation to the benefits of the slow, oxidative myogenic program to dystrophic mice. It confirms utrophin A as a therapeutic target in DMD and the slow, oxidative myogenic program as clinically relevant avenue towards treatment of the disease.
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Gerhalter, Teresa [Verfasser]. "Characterization of the dystrophic muscle by 23Na NMR and 1H NMR T2 spectrum / Teresa Gerhalter." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/118099423X/34.
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Maffioletti, S. M. "Generation of biocompatible human 3D skeletal muscle tissue from healthy and dystrophic pluripotent stem cells." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1556255/.
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Skeletal muscle is a tissue with remarkable regenerative abilities but a wide range of disorders can impair its functions. At present, there is no effective therapy for most of these pathologies and this represents a significant unmet medical need. The pursuit of therapeutic strategies has led to the development of different encouraging approaches. Importantly, tissue engineering is also emerging as a promising discipline for the establishment of new platforms with therapeutic relevance for muscle disorders. Generating human artificial skeletal muscles in vitro would indeed provide an invaluable tool for disease modelling, drug screening and tissue replacement. Nevertheless, skeletal muscle tissue engineering is extremely challenging and at present no commonly endorsed model is available. Specifically, one of the bottlenecks is the use of primary cells, which hold the drawback of scarce availability and reduced proliferation and differentiation potential in vitro thus limiting their use. Here I describe the generation of 3D artificial mini-muscles from human pluripotent stem cells derived from healthy donors and patients with muscular dystrophy. This has never been reported before and the use of pluripotent stem cells offers a virtually unlimited source of myogenic cells. These patient- and disease-specific human artificial mini-muscles recapitulate characteristics of the adult tissue and, importantly, are able to engraft into immunodeficient mice. Finally, I show that other isogenic cell types present in normal muscle tissue (such as endothelial cells and pericytes) can be derived and combined together with the same patient-specific myogenic cells, thus generating a multi-lineage artificial mini-muscle. This complex platform could provide a valuable tool for skeletal muscle disease modelling, drug screening and tissue replacement ultimately leading to the development of new therapies for muscle diseases.
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Gainer, Thomas Gregory. "Immune Response Markers are Prevalent in the mRNA Expression Profile of Maturing Dystrophic Murine Skeletal Muscle." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/33263.
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Duchenne muscular dystrophy (DMD) is a severe and fatal muscle wasting disease characterized by a high mutation rate in the gene that encodes the membrane-associated protein dystrophin that results in absence of expressed protein. Although the primary genetic defect for DMD is known, the mechanisms that initiate the onset of DMD are not currently understood. This study tested the hypothesis that pathophysiological processes involved in DMD could be identified by the global expression of mRNA in maturing dystrophin- and utrophin-deficient mouse (mdx:utrn-/-) muscles. Two potential dystrophic onset mechanisms targeted for analysis were (1) disrupted expression of calcium handling proteins; and, (2) increased expression of immune response markers.
An mRNA expression profile was developed following isolation of total RNA from control and mdx:utrn-/- triceps surae (TS) muscles at ages 9-10 and 20-21 days using Affymetrix® Mu74Av2 GeneChips®. Compared to control, the mRNA expression profile in mdx:utrn-/- muscles revealed there was a 3-fold increase in the number of gene transcripts differentially expressed more than 2-fold (53 transcripts at ages 9-10 days; 153 at ages 20-21 days). However, there were no changes in the mRNA transcripts for calcium handling proteins. In distinct contrast, there was up-regulation of transcripts that corresponded to an immune response (40 transcripts), extracellular matrix activity (14), and proteolysis (8). Up-regulation of several transcripts corresponded to cytokines and their receptors (11), chemokines and their receptors (5), and lymphoid and myeloid markers (16) suggesting that dystrophic muscle is susceptible to invasion by macrophages, leukocytes, B- and T-cells. These results are consistent with several reports (Spencer et al., 1997; Chen et al., 2000; Porter et al., 2002; Porter et al., 2003a; Porter et al., 2003b; Porter et al., 2004) that indicate the immune system may play an important role in the early pathophysiology of DMD. Understanding the functional aspects of an immune response in DMD onset should lead to more effective therapeutics.<br>Master of Science
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Moulay, Gilles. "APPROCHES DE THÉRAPIES GÉNIQUES POUR DES MALADIES NEUROMUSCULAIRES." Phd thesis, Université d'Evry-Val d'Essonne, 2010. http://tel.archives-ouvertes.fr/tel-00507450.
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La thérapie génique de myopathies telles que la dystrophie musculaire de Duchenne nécessite une approche systémique afin de traiter l'ensemble de la musculature. Le vecteur AAV est actuellement le plus efficace pour transduire le muscle. Nous montrons que la biodistribution du vecteur AAV administré par voie veineuse peut être modifiée en utilisant diverses stratégies adjuvantes chez la souris saine. La pré-injection de polymères permet ainsi d'améliorer la transduction des muscles par le vecteur AAV, ou encore de baisser la réponse immune neutralisante induite par l'injection intraveineuse du vecteur. Nous abordons également l'impact de facteurs modulateurs exogènes ou endogènes – tels que la procédure d'administration ou certains facteurs sanguins – sur la transduction systémique de l'AAV. Dans une seconde approche, nous avons évalué le transfert de gènes dans le muscle dystrophique afin de sécréter dans la circulation sanguine une protéine transgénique fusionnant le récepteur soluble I du TNF-α avec le fragment constant d'une immunoglobuline (TNFR-Is/mIgG1). La comparaison des cinétiques de sécrétion obtenu après le transfert de gène dans le muscle de souris saines ou de souris dystrophiques mdx indique que le contexte inflammatoire du muscle dystrophique favorise une réponse immune contre le transgène. Nous montrons que l'expression et la sécrétion d'un variant murin peu immunogène du TNFR-Is/mIgG1 améliore la fonction musculaire de la souris mdx sans toutefois conférer un avantage sélectif aux fibres musculaires dystrophiques qui continuent leur cycle de nécrose et de régénération.
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Fair, Jeanette L. "Effects of compensatory hypertrophy on dystrophic (Bio 14.6) hamster muscle : changes in collagen and myofibrillar protein content." Virtual Press, 1987. http://liblink.bsu.edu/uhtbin/catkey/494971.
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Compensatory hypertrophy was induced on the plantaris (PL) and soleus (SOL) muscles of five week old normal and dystrophic (strain 14.6) hamsters. This was done to indicate whether submaximal exercise would be beneficial in reducing the progression of the muscular dystrophy (i.e., by causing muscle hypertrophy, reducing the total collagen content, and increasing the total protein content of the diseased muscle to approximate that of normal tissue).The hamsters were divided into four groups: 1) dystrophic overload (DO), 2) dystrophic control (DC), 3) normal overload (NO), and 4) normal control (NC). Eight weeks of overload of the PL and SOL muscles was induced by surgical ablation of the synergistic gastrocnemius muscle. Muscle wet weight data indicated significant muscle hypertrophy of 125% and 92% in the NO and DO PL respectively, and 60% in the NO SOL. Dry muscle weight data was comparable to the above results. There was no significant difference in the muscle collagen content between the NC and DC groups. Collagen content increased significantly in the NO and DO PL by 81% and 41% respectively, and in the NO and DO SOL by 127% and 57% respectively. The DC muscle was significantly lower in protein content than the NC muscle (180.2mg/g and 210.1 mg/g respectively) when expressed per g of wet muscle weight. This significance disappears when expressed per g dry muscle weight. The overload caused a significant decrease in the protein content of only the NO group when expressed by both wet and dry tissue weights (171.7mg/g and 678.3mg/g rrespectively). The hydration of the DC group was significantly higher than the NC group. The overload resulted in a significant increase in the water content of only the NO muscle.The results of this study indicate that dystrophic muscle will hypertrophy as indicated by muscle weight data. However, the significance of the data from the total collagen and total protein determination of the overload groups was inconclusive due to the formation of scar tissue. This scar tissue resulted in high collagen content. The high glycine content in this collagen in turn resulted in low protein values.
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Nahirney, Patrick Charles. "Morphological quantitative and ultracytochemical studies on the internal membrane systems of normal and mdx-dystrophic murine skeletal muscle fibers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/NQ48681.pdf.
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Acharyya, Swarnali. "Elucidating molecular mechanisms of muscle wasting in chronic diseases." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180096565.
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Pasalic, Dario. "No Calpain, No Gain: Newly Developed Procedures for the Separation and Characterization of The Calpain Family of Proteins in Human Dystrophic and Non-dystophic Muscle." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146022.
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Muscular dystrophy is a disease which gradually deteriorates skeletal muscle cells, leading to the eventual death of such cells and the surrounding tissue. Calpains are Ca2+- dependent proteases and together with the Ca2+-dependent specific inhibitor of calpains, calpastatin, are widely distributed in eukaryotic cells. It has been suggested that part of the enhanced deterioration in the dystrophic state is due to enhanced calpain activity; therefore analysis of normal and dystrophic muscle was essential. Conventional techniques for the isolation and characterization of calpain and calpastatin utilize relatively large muscle samples (>100g), whereas biopsy or post-mortem samples are considerably less than this. Thus, the initial and main objective of this project was to develop methods suitable for purification and analysis of the calpain family from limited muscle samples. With these restrictions in mind, techniques were developed for samples ranging from 0.2-1g, a realistic biopsy extraction. The hypothesis to be further evaluated is that some dystrophies are characterized by increased calpain activity, caused either by an increased expression of m- or μ- calpain or decreased inhibition by calpastatin, or both. The procedures are now in place to test this hypothesis further and extensive analyses are required using defined dystrophic types and increased sampling numbers.
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Dias, Wilson Vinicius. "Adaptations du métabolisme musculaire en réponse à l’exercice et à une supplémentation en antioxydants chez des patients atteints de Dystrophie Fascioscapulohumérale." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTT030.
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La dystrophie FacioScapuloHumérale (FSHD), décrite pour la première fois en 1885 par Landouzy Dejerine, est la première dystrophie musculaire de l’adulte en France affectant entre 4000 et 5000 personnes. La destruction progressive des fibres musculaires entraîne une atrophie et une faiblesse musculaires s’aggravant progressivement, avec cependant une grande variabilité intra-familiale du degré des atteintes. Une caractéristique de l’atteinte musculaire est généralement son asymétrie. Les premières manifestations concernent souvent les muscles du visage, les muscles de l’omoplate et des muscles perihuméraux. En progressant la pathologie va toucher d’autres territoires musculaires. Dans environ 10 à 15 % des cas, à un stade évolué, les patients sont contraints d'utiliser un fauteuil roulant. En dépit d’avancées majeures dans la compréhension du locus morbide, les mécanismes exacts responsables des défauts musculaires de la FSHD ne sont toujours pas compris et il n’existe aucune thérapie. Toutefois, il existe de plus en plus de données qui permettent une implication probable du stress oxydant dans cette pathologie. L’hypothèse selon laquelle les réponses antioxydantes sont altérées dans la FSHD s’appuie sur des dérégulations d’enzymes impliqués dans le stress oxydant. Une étude prospective réalisée sur des patients FSHD et des volontaires sains nous a ainsi permis de mettre en évidence une corrélation entre le stress oxydant systémique et musculaire et leurs déficits fonctionnels musculaires. Ces données nous ont conduit à la mise en place d’un essai clinique randomisé, contrôlé, en double aveugle contre placébo, visant à évaluer les effets d’une supplémentation en antioxydants chez 54 patients atteints de FSHD pendant 17 semaines. Cet essai a ainsi permis de montrer une augmentation significative de la force et l’endurance des quadriceps corrélée à une diminution du stress oxydant et une augmentation des défenses antioxydantes chez les patients atteints de FSHD. De nombreuses caractéristiques de la FSHD pourraient être causées et/ou exacerbées par des perturbations de la production des espèces radicalaires ou une réponse non adaptée à cette production. Aussi le premier objectif de ma thèse est de mener une étude comparative des profils d’oxygénation par spectroscopie dans le proche infrarouge de patients atteints de FSHD et sains. Le second objectif est d’évaluer l’effet de la supplémentation en antioxydant sur le volume des quadriceps par IRM et leur qualité musculaire déterminée par le ratio Force/Volume musculaire du quadriceps et d’évaluer les corrélations entre ces variables, la force et le stress oxydant. Les données obtenues ont permis de montrer une réduction de la capacité oxydative lors d’une contraction isométrique volontaire des quadriceps et ont permis d’étudier l’effet de la supplémentation sur les volumes et la qualité musculaire des quadriceps. Ces augmentations sont associées non seulement à une augmentation de la force des quadriceps mais aussi à une diminution du stress oxydant et une augmentation des défenses antioxydantes. L’ensemble de ces données montrent que le stress oxydant pourrait jouer un rôle important dans la FSHD et qu’une approche antioxydante semble adaptée à cette pathologie. Des analyses plus fines sur l’action des espèces réactives de l’oxygène (ROS) et leurs sources pourraient contribuer à une meilleure compréhension des bases physiopathologiques de la FSHD<br>Facioscapulohumeral muscular dystrophy (FSHD), first described in 1885 by Landouzy Dejerine, is the most common inherited skeletal muscle disease of adult life affecting 4000 to 5000 persons in France. Progressive evolution of the disease leads to progressive weakness and atrophy of muscle fibers associated to a wide variability. The pattern of muscle weakness is often asymmetrical and the rate and extent of progression may vary considerably with sudden periods of unexplained rapid disease progression. This muscle disorder is characterized by progressive muscle weakness, beginning with facial muscles and the shoulder girdle, followed by the pelvic girdle and the muscles of the lower extremities. In 10 to 15% of cases, patients need to use a wheelchair. Despite major progress in the understanding of the genetic basis of FSHD, the exact mechanisms that lead to FSHD defects are not completely understood and no curative treatment is available. However, there is growing evidence that oxidative stress may contribute to FSHD pathology. The hypothesis that oxidative stress responses might be specifically altered in FSHD is supported by the deregulation of enzymes involved in oxidative stress.A prospective study realized with FSHD patients and healthy subjects unrevealed the correlation between systemic and muscular oxidative stress and functional muscle defects. Based on these data, we organized a randomized, double-blind, placebo-controlled pilot clinical trial in order to evaluate the effects of 17 weeks antioxidant supplementation in 54 FSHD patients. This clinical trial demonstrates a significant increase in muscle force and quadriceps endurance correlated to a decrease in oxidative stress and an increase in antioxidant defense in FSHD patientsFurthermore, many FSHD features may be caused or exacerbated by perturbations in the production of free radicals or inappropriate response to such stressors. Therefore the first objective was planned to investigate muscle oxygenation patterns during and after a MVCQ by near-infrared diffuse optical spectroscopy (NIRS). The second objective is to evaluate the effect of antioxidant supplementation on quadriceps volumes by IRM and determine the muscle quality using Strength/ Volume ratio of quadriceps muscles and correlate this variables with force and oxidative stress parameters.The major findings of this study show a significant decrease in oxidative capacity during voluntary isometric contraction in quadriceps and demonstrate the effect of supplementation on muscle volume and quality. Indeed, vitamin E, vitamin C, zinc and selenium supplementation improves muscle volume and quality of both quadriceps by enhancing the antioxidant defences and reducing oxidative stress.This increase are associated to increase in strength and decrease in oxidative stress and increase in antioxidant defences. Taken together, we show that oxidative stress plays an important role in FSHD and that an anti-oxidant strategy adapted to the FSHD-specific “oxidative stress” may be a relevant therapeutic approach for these patients. Further analyses of ROS production and sources could contribute to a better understanding of the pathophysiological mechanisms implicated in FSHD
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Lekan, Jaimy Marie. "Exercise-induced mechanisms of muscle adaptation in mdx mice." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1095372379.
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Deol, Jatinderpal. "Development of helper-dependent adenovirus for gene expression in muscle." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33745.
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Duchenne muscular dystrophy (DMD) is characterized by necrosis and progressive loss of muscle fibers. DMD patients have a mutation in the gene encoding dystrophin, a large membrane-associated cytoskeletal protein on the cytoplasmic side of the sarcolemma. Gene therapy using fully deleted adenoviral vectors shows great potential for the eventual treatment of DMD and other genetic diseases. These vectors are less immunogenic than their predecessors and have the capacity to carry large DNA inserts such as the full-length dystrophin (12 kb). However, the lack of viral genes results in a weakened and subsiding (short) transgene expression in muscle. Findings in the lung and liver have shown the adenoviral E4 region, in particular E4 open reading frame 3 (ORF3) to contribute to the maintenance of transgene expression. We constructed an adenovirus in which E4 ORF3 was reintroduced into a fully-deleted adenovirus along with full-length dystrophin (AdCBDysORF3). Dystrophin levels produced by AdCBDysORF3 were found to be not sustained in mdx mice, dropping significantly by day 90. However, expression levels did increase when AdCBDysORF3 was complemented with other viral proteins such as EIB. Likewise, increasing the expression of the primary adenovirus receptor (CAR) in muscle also resulted in a higher initial dystrophin expression in myofibers.
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Judge, Luke Milburn. "Dissecting the signaling and mechanical functions of the dystrophin-glycoprotein complex in skeletal muscle /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/4989.
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Chevron, Marie-Pierre. "Dystrophine et utrophine dans les dystrophies musculaires et au cours du développemnt des muscles squelettique, cardiaque et lisse humains." Montpellier 1, 1994. http://www.theses.fr/1994MON1T023.
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Johnson, Eric K. "A new model for the dystrophin associated protein complex in striated muscles." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354554580.
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Lecroisey-Leroy, Claire. "Caractérisation moléculaire et cellulaire de la dégénérescence musculaire dépendante de la dystrophine chez le nématode Cænorhabditis elegans." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10152.
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La Dystrophie Musculaire de Duchenne (DMD) est la plus fréquente et la plus sévère des maladies dégénératives du muscle. Elle se caractérise par une dégénérescence progressive des fibres musculaires due à l’absence de dystrophine fonctionnelle dans les muscles. Actuellement, le rôle physiologique de la dystrophine n’est pas clairement établi et il n’existe pas encore de traitement curatif pour cette maladie. La difficulté de mettre en évidence la fonction de la dystrophine et la physiopathologie de la DMD est en partie expliquée par la complexité moléculaire et cellulaire du muscle des modèles vertébrés utilisés dans les études actuelles. Notre équipe de recherche a développé un modèle de DMD chez le nématode Caenorhabditis elegans. Dans ce modèle, la mutation du gène de la dystrophine, provoque une dégénérescence progressive des muscles conduisant à une paralysie des animaux adultes. Nous utilisons ce modèle afin d’étudier la fonction de la dystrophine et les mécanismes impliqués dans la dégénérescence musculaire chez le nématode. Ce travail de thèse porte sur deux nouveaux acteurs de la dégénérescence musculaire dépendante de la dystrophine : la protéine DYC‐1 et son principal partenaire ZYX‐1. Ce travail présente la caractérisation de ces deux protéines et étudie leurs fonctions dans le muscle. Par ailleurs, ce travail de thèse présente les premiers résultats d’un projet de microscopie électronique ayant pour but de caractériser en détail les évènements subcellulaires du processus dégénératif au cours du cycle de vie du nématode dystrophique. À plus long terme, les études chez le nématode permettront de proposer de nouvelles hypothèses quant aux mécanismes moléculaires et cellulaires de la dégénérescence musculaire<br>Duchenne Muscular Dystrophy (DMD) is the most prevalent and one of the most severe muscular dystrophy. DMD is due to the absence of functional dystrophin in cardiac and skeletal muscle cells, this lack leads to a progressive muscle degeneration of contractile fibres. Currently, the physiological role of dystrophin is not yet clearly established and curative treatments for DMD are not yet available. The lack of knowledge about dystrophin function and DMD physiopathology can be partly attributed to the complexity of vertebrate muscle, and the absence of a simple model that emulates the human pathology. Our research team developed a model of muscle degeneration in the nematode Caenorhabditis elegans. In this model, the mutation of the dystrophin gene produces a progressive muscle degeneration leading to the paralysis of the adult worms. We use this model for investigating the role of dystrophin and the mechanisms of muscle degeneration in C. elegans. This PhD work concerns two new actors of dystrophin‐dependant muscle degeneration: The DYC‐1 protein and its main interactor ZYX‐1. This study aims to characterise these proteins and to study their muscle functions. Moreover, this PhD work presents preliminary results of an in depth characterisation of subcellular processes of muscle degeneration in dystrophic worms by electron microscopy. Our aim is to visualise first events and to observe the progression of degeneration until the death of muscle cell. These molecular and cellular approaches aims to get new insights in the mechanisms underlying muscle degeneration in order to propose new hypotheses for the understanding of DMD
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Chassagne, Julie. "Mécanismes moléculaires impliqués dans l’efficacité de transduction des vecteurs AAV dans le muscle dystrophique." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS514.pdf.
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La Dystrophie Musculaire de Duchenne (DMD) est une maladie génétique causée par l’absence de dystrophine et provoquant une dégénérescence musculaire sévère. Aucun traitement curatif n’existe aujourd’hui mais la thérapie génique par vecteur AAV est l’une des stratégies les plus prometteuses pour traiter la DMD. Malgré l’efficacité bien établie de l’AAV de sérotype 8 (AAV8) pour le transfert de gène dans le muscle, de fortes doses de vecteurs sont nécessaires pour obtenir une efficacité thérapeutique dans des modèles animaux de la DMD. Dans ce contexte, j’ai étudié les mécanismes qui peuvent limiter l’efficacité de transduction du vecteur AAV8 dans le muscle dystrophique. Pour cela, j’ai étudié le devenir du vecteur AAV dans le muscle DMD puis caractérisé le système endosomal, essentiel au transport et la maturation des vecteurs AAV, dans différents modèles de la DMD. Mes résultats ont montré que l’efficacité de transduction de l’AAV8 est plus faible dans les cellules musculaires DMD comparées aux contrôles. De plus, la dérégulation du système endosomal dans la DMD peut impacter le transfert de gène par vecteur AAV dans ces cellules. Par ailleurs, l'amélioration de l'efficacité des vecteurs AAV en thérapie génique nécessite aussi une meilleure connaissance des protéines cellulaires qui interagissent avec le génome viral et qui régulent son expression. Dans ce contexte, nous avons montré que les facteurs de transcription RFX1 et RFX3 sont capables d’interagir avec la région ITR du génome viral et de moduler l’expression des vecteurs AAV<br>Duchenne Muscular Dystrophy (DMD) is a genetic disorder caused by the absence of dystrophin and causing severe muscle degeneration. No curative treatment exists today but AAV-based gene therapy is one of the most promising strategies for treating DMD. Despite the well-established efficacy of AAV serotype 8 (AAV8) for gene transfer into muscle, high doses of vectors are required to achieve therapeutic efficacy in DMD animal models. In this context, I aimed at investigating the mechanisms that may limit the transduction efficiency of the AAV8 vector in dystrophic muscle. For this, I studied the fate of the AAV vector in the DMD muscle and then characterized the endosomal system, essential for the transport and maturation of AAV vectors, in different models of DMD. We have shown that the transduction efficiency of AAV8 is lower in DMD muscle cells compared to controls. The dysfunction of the endosomal system identified in this study may impact AAV vector gene transfer into these cells. Moreover, improving the efficiency of AAV vectors in gene therapy also requires a better understanding of cellular proteins that interact with the viral genome and regulate its expression. In this context, we have shown that the transcription factors RFX1 and RFX3 are able to interact with the ITR region of the viral genome and to modulate the expression of AAV vectors
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Bestard, Jennifer. "Dystrophin gene regulation in muscle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/MQ54086.pdf.
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Woolf, Peter James. "Cardiac calcium handling in the mouse model of Duchenne Muscular Dystrophy." University of Southern Queensland, Faculty of Sciences, 2003. http://eprints.usq.edu.au/archive/00001525/.
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The dystrophinopathies are a group of disorders characterised by cellular absence of the membrane stabilising protein, dystrophin. Duchenne muscular dystrophy is the most severe disorder clinically. The deficiency of dystrophin, in the muscular dystrophy X-linked (mdx) mouse causes an elevation in intracellular calcium in cardiac myocytes. Potential mechanisms contributing to increased calcium include enhanced influx, sarcoplasmic reticular calcium release and\or reduced sequestration or sarcolemmal efflux. This dissertation examined the potential mechanisms that may contribute to an intracellular calcium overload in a murine model of muscular dystrophy. The general cardiomyopathy of the mdx myocardium was evident, with the left atria from mdx consistently producing less force than control atria. This was associated with delayed relaxation. The role of the L-type calcium channels mediating influx was initially investigated. Dihydropyridines had a lower potency in contracting left atria corresponding to a redued dihydropyridine receptor affinity in radioligand binding studies of mdx ventricular homogenates (P<0.05). This was associated with increased ventricular dihydropyridine receptor protein and mRNA levels (P<0.05). The function of the sarcoplasmic reticulum in terms of release and also sequestration of calcium via the sarco-endoplasmic reticulum ATPase were investigated. A lower force of contraction was evident in mdx left atria in response to a range of stimulation frequencies (P<0.05) and concentrations of extracellular calcium (P<0.05). However, in the presence of 1 nM Ryanodine to block sarcoplasmic reticular calcium release, increased stimulation frequency caused similar forces to those obtained in control mice suggesting enhanced calcium influx via L-type calcium channels in mdx. Rapid cooling contractures showed a reduced contracture in mdx compared to control in response to cooling. This suggests some dysfunction in SR storage, which may be associated with the delayed relaxation time. Concentration-response curves to inhibitors of the sarco-endoplasmic reticulum showed no difference in function of the enzyme responsible for calcium uptake into the sarcoplasmic reticulum. Although sarco-endoplasmic reticulum ATPase mRNA was upregulated, no functional benefit was evident. This study indicates that a deficiency of dystrophin leads to upregulation of L-type calcium channels that contribute to increased calcium influx, with no functional change in sarcoplasmic reticular sequestration. Upregulation of the influx pathway is a potential mechanism for the calcium overload observed in mdx cardiac muscle.
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Sperringer, Justin Edward. "Chronic Dietary Supplementation of Branched-Chain Amino Acids Does Not Attenuate Muscle Torque Loss in a Mouse Model of Duchenne Muscular Dystrophy." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/93577.
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Duchenne Muscular Dystrophy (DMD) is an X-linked recessive, progressive muscle-wasting disease characterized by mutations in the dystrophin gene. Duchenne muscular dystrophy is the most common and most severe form of inherited muscle diseases, with an incidence of 1 in 3,500 male births1,2. Mutations in the dystrophin gene result in non-functional dystrophin or the complete absence of the protein dystrophin, resulting in necrosis and fibrosis in the muscle, loss of ambulation, cardiomyopathies, inadequate or failure of respiratory function, and decreased lifespan. Although there has been little research for effective nutritional strategies, dietary intervention may be effective as an adjuvant treatment. In this study, wild type (WT) and mdx animals were provided either a control or elevated branched chain amino acid (BCAA) diet nocturnally for 25 weeks to determine if the elevated BCAAs would attenuate muscle torque loss.
Twenty-five weeks of chronic, elevated BCAA supplementation had no impact on muscle function measures. Interestingly, mdx and WT animals had the same torque responses in the low stimulation frequencies (1 Hz – 30 Hz) compared to higher stimulation frequencies. Tetanus was reached at a much lower stimulation frequency in mdx animals compared to WT animals (100 Hz vs +150 Hz). The mdx mouse consistently had more cage activity in the light cycle X- and Y-planes. Interestingly, animals on the BCAA diet increased X-, Y-, and Z-plane activity in the dark cycles at four weeks while animals on the control diet more Z-plane activity at 25 weeks, although not significant. All three BCAAs were elevated in the plasma at 25 weeks, although only Leu was significantly elevated. The BCAAs had no effect on. The diaphragm and skeletal muscle masses were larger in mdx animals, and WT animals had a significantly larger epididymal fat pad. The active state of BCKDC determined by phosphorylation of the E1α enzyme was greater in WT animals in white skeletal muscle, but not red skeletal muscle. Protein synthesis effectors of the mTORC1 signaling pathway and autophagy markers were similar among groups. Wild type animals had increased mTORC1 effectors and animals on the BCAA diet had decreased autophagy markers, although not significant.
Although BCAAs did not affect muscle function, fibrosis, or protein synthesis effectors, this study illustrates the functionality of mdx muscles over time. It would be interesting to see how the different muscle fiber types are affected by DMD, noting the differences between the diaphragm, heart, red muscle, and white muscle fibrosis markers. Although there was no increase in mTORC1 effectors with an elevated BCAA diet, it would be interesting to determine muscle protein synthesis, myofibrillar protein synthesis, and total protein turnover in the mdx mouse with an elevated BCAA diet, although the dietary intervention started when mice arrived at 4 weeks of age, earlier intervention may be beneficial early in the disease process.<br>Doctor of Philosophy<br>Duchenne Muscular Dystrophy (DMD) is an X-linked recessive, progressive muscle-wasting disease characterized by mutations in the dystrophin gene. Duchenne muscular dystrophy is the most common and most severe form of inherited muscle diseases, with an incidence of 1 in 3,500 male births1,2. Mutations in the dystrophin gene result in non-functional dystrophin or the complete absence of the protein dystrophin, resulting in necrosis and fibrosis in the muscle, loss of movement and walking ability, cardiomyopathies, inadequate or failure of respiratory function, and decreased lifespan. Although there has been little research for effective nutritional strategies, dietary intervention may be effective as an adjuvant treatment and palliative care. The branched chain amino acids (BCAAs) are known to directly stimulate muscle protein synthesis by direct activation of the mechanistic target of rapamycin complex 1 (mTORC1). This study aimed to illustrate the differences between diseased and healthy mice and determine if BCAAs can reduce muscle torque loss. Twenty-five weeks of chronic, elevated BCAA supplementation had no impact on muscle function measures. Interestingly, mdx and WT animals had the same torque responses in the low stimulation frequencies (1 Hz – 30 Hz) compared to higher stimulation frequencies. Tetanus was reached at a much lower stimulation frequency in mdx animals compared to WT animals (100 Hz vs +150 Hz). The mdx mouse consistently had more cage activity in the light cycle X- and Y-planes. Interestingly, animals on the BCAA diet increased X-, Y-, and Z-plane activity in the dark cycles at four weeks while animals on the control diet more Z-plane activity at 25 weeks, although not significant. All three BCAAs were elevated in the plasma at 25 weeks, although only Leu was significantly elevated. The BCAAs had no effect on. The diaphragm and skeletal muscle masses were larger in mdx animals, and WT animals had a significantly larger epididymal fat pad. The active state of BCKDC determined by phosphorylation of the E1α enzyme was greater in WT animals in white skeletal muscle, but not red skeletal muscle. Protein synthesis effectors of the mTORC1 signaling pathway and autophagy markers were similar among groups. Wild type animals had increased mTORC1 effectors and animals on the BCAA diet had decreased autophagy markers, although not significant. Although BCAAs did not affect muscle function, fibrosis, or protein synthesis effectors, this study illustrates the functionality of mdx muscles over time. It would be interesting to see how the different muscle fiber types are affected by DMD, noting the differences between the diaphragm, heart, red muscle, and white muscle fibrosis markers. Although there was no increase in mTORC1 effectors with an elevated BCAA diet, it would be interesting to determine muscle protein synthesis, myofibrillar protein synthesis, and total protein turnover in the mdx mouse with an elevated BCAA diet, although the dietary intervention started when mice arrived at 4 weeks of age, earlier intervention may be beneficial early in the disease process.
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Barthélémy, Florian. "La modularité de la dysferline peut-elle permettre le développement d'approches thérapeutiques?" Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5035.
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Durant ma thèse, mes recherches se sont principalement portées sur l'identification des propriétés modulaires de la dysferline, une protéine impliquée dans des dystrophies musculaires, afin d'identifier les approches thérapeutiques les plus prometteuses. Mon travail s’est donc orienté selon deux axes de recherche, une approche par « mini-protéines » et une approche par «saut d’exon », toutes deux basées sur des preuves de principe obtenues chez des patients. Nous avons tout d'abord testé une approche de saut d'exon pour l'exon 32 de DYSF. Nous avons pu établir la fonctionnalité de cette protéine tronquée en permettant son expression dans des cellules de patients déficients en dysferline. Ceci a suggéré que le domaine C2D (encodé par les exons 31 à 34) n'est pas essentiel pour la dysferline puisque l'absence d'une partie de celui-ci n'empêche pas sa fonctionnalité. Nous avons dans le même temps analysé les caractéristiques d'autres domaines de la dysferline, en créant des miniprotéines contenant différentes combinaisons de domaines. Nous avons montré que la partie C-terminale de la dysferline (composée des deux derniers domaines C2 et du passage transmembranaire) était essentielle et suffisante pour la fonctionnalité de la dysferline dans le muscle. L'ensemble de ces résultats démontre que certains domaines de la dysferline sont dispensables, ouvrant ainsi la voie à l'étude d'approches de thérapie génique basé sur les minigènes ou le saut d'exon pour les dysferlinopathies<br>During my thesis, my researches have mainly concerned the modular properties of dysferlin, a protein involved in muscular dystrophies, in order to identify the most promising therapeutic approaches.My work has been oriented within two research axes, a mini-proteins approach and an exon-skipping approach, both based on proofs of concept obtained in patients. We first tested an exon-skipping approach for the exon 32 of DYSF, based on the identification of a protein lacking the encoded part of this exon, in an asymptomatic person. We have established the functionality of this truncated protein by allowing its expression in dysferlin-deficient patients' cells. This suggests that the C2D domain (encoded by exons 31 to 34) is not essential for dysferlin since the absence of a part of it don't block its functionality.In the same time we analyzed the characteristics of the others domains of dysferlin, by creating miniproteins containing different combinations of domains. By studying the abilities of this constructs, we have showed that the C-ter part of dysferlin (composed of the last C2 domains and the transmembrane domain) was essential and sufficient for the functionality of dysferlin in muscle. All these results demonstrate that several domains of dysferlin are dispensable, paving the way for studying gene therapy approaches, based on minigenes or exon-skipping for dysferlinopathies
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Brouilly, Nicolas. "Dégénérescence musculaire chez Caenorhabditis elegans : caractérisation morphologique et étude de suppresseurs." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10143/document.
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Les dystrpohies musculaires sont des maladies génétiques rares qui se caractérisent par une dégénérescence musculaire progressive. la Dystrophie Musculaire de Duchenne (DMD) qui est la plus sévère d'entre elles est due à des mutations dans le gène de la dystrophine. Les mécanismes cellulaires impliqués dans le processus de dégénérescence des muscles restent peu compris et aucun traitement efficace n'existe à ce jour. Notre équipe a développé un modèle de la DMD chez le nématode C. elegans qui présente une dégénérescence musculaire progressive. Pendant ma thèse, j'ai caractérisé le processus de dégénérescence musculaire chez ce modèle par microscopie électronique. J'ai également contribué à une étude du rôle des mitochondries dans la dégénérescence musculaire dystrophine-dépendante chez le nématode. Par ailleurs, j'ai étudié l'effet de suppresseurs pharmacologique et génétiques de la dégénérescence musculaire dystrophine-dépendante. Enfin, j'ai pu mettre en évidence que la force exercée par le muscle influence le taux de dégénérescence musculaire. L'ensemble des résultats obtenus au cours de ma thèse, suggèrent que la perte de fonctions de la dystrophine affecte chez le nématode l'intégrité du sarcolemme et des structures d'ancrage des sarcomères et déclenche ainsi une cascade d'événements intracellulaires conduisant in fin à la mort de la cellule musculaire. Ainsi mes travaux dethèse mettent en évidence de nouveau mécanismes cellulaires impliqués dans la dégénérescence musculaire et ouvrent de nouvelles perspectives pour le développement de thérapie visant à cibler les défauts primaires ou secondaires induits par la perte de fonction de la dystrophine<br>Muscle dystrophies are genetic diseases caraterized by progressive muscle degeneration. Duchenne Muscular Dystrophy (DMD) is the most severe and is due to a mutation in the gene coding the dystrophin protein. The cellular mechanisms implicated in the degenerating process arte not understood yet and there is still no efficient treatment to cure the disease. Our group decvelopped a DMD model in C. elegans that presents progressive muscle degeneration. During my PhD thesis, I characterized the process of muscle degeneration in this model by electron microscopy. I also contribued to an investigation of the role of mitochondira in dystophin-dependant muscle degeneration. I also studied the effect of pharmacological and genetic suppressors of muscle degeneration. Finally, I showed that the force developped by the worm to move influences the level of muscle degeneration. Altogether, the results I obtained during my PhD thesis, suggest that the loss of funciotnof the dystrophin protein affects the integrity of the muscle plasma membrane and the sarcomeres anchoring structures triggering a cascade of intracellular events leading to the muscle cell death in C. elegans. Therefore, my results highlight new cellular mechanisms implicated in the phenomenon of muscle degeneration and open new perspectives for the development of therapies targeting primary and secondary defects induced by the dystrophin loss of function
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Sommer, Barbara. "Changes of skeletal muscle in adult dystrophin-deficient cats /." [S.l.] : [s.n.], 2000. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Guibinga, Ghiabe H. "Molecular therapeutic interventioan for dystrophin-deficient muscles." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36945.
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Duchenne muscular dystrophy (DMD) is common and fatal X-linked genetic disorder. The overall objective of this thesis was to carry out a prospective study for dystrophin gene therapy in dystrophic muscles, using the X-linked muscular dystrophy (mdx) mouse model. Recombinant adenovirus (AdV) is presently the vehicle of choice for gene therapy for a number of diseases including DMD. However AdV possess two major limitations when utilized as vectors in skeletal muscles: (i) the maturation-dependency of AdV-infectivity in skeletal muscles, (ii) the host immune response against adenoviral proteins as well as the transgene product. Thus, the work presented in this thesis addresses these two major limiting factors. By modifying either the host or the vectors, we have attempted to optimize AdV-mediated therapeutic gene transfer in dystrophic muscle. Our strategy has consisted firstly to evaluate the regenerative response of dystrophic muscle with advanced disease after experimentally-induced regeneration, in an attempt to recapitulate the myogenic program. We report that mdx mice with severe dystrophic pathology can still show a substantial level of muscle repair with attendant generation of immature myofibers. Secondly, by taking advantage of this level of regeneration and the concomitant generation of immature myofibers, we have upregulated expression of the coxsackie adenovirus receptor (CAR) present in mdx muscles. We have delivered AdV containing a dystrophin gene (AdV-Dys) at a period corresponding to this peak level of CAR expression and we have reported a significant increase of the number of dystrophin expressing myofibers with a net trend toward muscle function amelioration.<br>The work of this thesis also reports that the combined blockade of calcineurin and CD28 signaling, two key and distinct elements needed for an effective immune response, effectively blunted the immune-mediated destruction of dystrophin expressing myofibers expressed after AdV-Dys delivery. As an alternative to host modification (regeneration and immunosuppression) that can be associated with potential toxic effects, we have explored a strategy where by the recombinant AdV vector contains a less immunogenic transgene utrophin. We report that overexpression of utrophin and dystrophin by AdV-mediated gene transfer in adult immunocompetent mdx mice produces differential effects on muscle cell function in adult immunocompetent (mdx) mice. (Abstract shortened by UMI.)
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Wang, Yu Xin. "Molecular Regulation of Muscle Stem Cell Self-Renewal." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35207.
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Muscle stem cells self-renew to maintain the long-term capacity for skeletal muscles to regenerate. However, the homeostatic regulation of muscle stem cell self-renewal is poorly understood. By utilizing high-throughput screening and transcriptomic approaches, we identify the critical function of dystrophin, the epidermal growth factor receptor (EGFR), and fibronectin in the establishment of cell polarity and in determining symmetric and asymmetric modes of muscle stem cell self-renewal. These findings reveal an orchestrated network of paracrine signaling that regulate muscle stem cell homeostasis during regeneration and have profound implications for the pathogenesis and development of therapies for Duchenne muscular dystrophy.
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Guiraud, Simon. "Evaluation de régulateurs positifs de la croissance musculaire chez un modèle dystrophique murin." Thesis, Evry-Val d'Essonne, 2011. http://www.theses.fr/2011EVRY0014/document.
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En 1997, le caractère culard, un phénotype hypermusclé chez le bovin, est attribué à des mutations dans le gène de la myostatine (MSTN). Depuis, il a été confirmé qu’une baisse de l’activité de la MSTN conduisait à une augmentation de la masse musculaire chez d’autres espèces, y compris chez l’Homme. L’identification de ce facteur et des conséquences de son invalidation sur le développement musculaire ouvre de nombreuses perspectives en médecine humaine comme, par exemple, chez des personnes ayant eu une fonte musculaire importante suite à une immobilisation prolongée ou en conséquence du vieillissement ou d’une maladie chronique. L’objectif majeur de ce projet de recherche a consisté à évaluer de nouvelles stratégies permettant d’augmenter la masse musculaire chez la souris. Pour ce faire, nous nous sommes intéressés à une métalloprotéine de la matrice extracellulaire (MEC), la décorine (DCN), dont l’interaction avec la MSTN a été caractérisée comme étant zinc dépendante. Suite à l’injection de ce Small Leucine Rich Proteoglycan (SLRP) chez la souris dystrophique mdx et Gamma-sarcoglycan-/-, nous avons constaté une augmentation de la masse musculaire consécutive à un phénomène d’hypertrophie associé ou non à de l’hyperplasie. Des études de dose/cinétique ont montré que l’effet positif de la décorine sur la croissance musculaire était maximal 21 jours après administration. Nous avons également découvert qu’un fragment peptidique de 41 acides aminés du domaine N-terminal de la protéine DCN murine conservait une activité anti-myostatine et induisait une hypertrophie musculaire chez la souris dystrophique. Ce domaine, site de l’interaction directe entre la MSTN et la DCN, présente un motif CX3CXCX6C, caractéristique des SLRPs de classe I, dont le cluster de cystéines et son interaction avec le zinc ont été décrits comme indispensables à l’activité anti-MSTN de la DCN. Différentes études concernant les mécanismes induits lors de la séquestration de la MSTN par la DCN dans la MEC ont également été conduites afin d’expliquer les phénomènes observés chez la souris. Enfin, nous avons étudié le potentiel de la DCN pour favoriser la greffe de cellules myogéniques et développé différentes approches de thérapie génique<br>In 1997, the double-muscling phenotype, a marked hypermuscularity in cattle, was related to mutations in the myostatin (MSTN) gene. Since, it was confirmed that a decrease of the myostatin’s activity drives an increase of the muscular mass in others species, including Human. The identification of this factor and the consequences of its invalidation on the muscular development open many perspectives in human medicine, as, for example, for people whom have an important muscular loss fallow up an extended immobilization or in consequence of old age or a chronic disease. The main purpose of this research project was to evaluate some new strategies permitting the increase of the muscular mass in mice. To achieve that, we investigated in detail the decorin (DCN), a metalloprotein of the extracellular matrix (ECM), interacting with MSTN in a zinc-dependent manner. After intramuscular injection of this Small Leucine Rich Proteoglycan (SLRP) in mdx and Gamma-Sarcoglycan-/- dystrophic mice, we observed a significant increase of the muscle mass conducted by hypertrophy associated or not with hyperplasia. Dose and cinetic studies showed that the positive effect of the decorin on muscular growth was maximal 21 days after administration. Furthermore, we showed that a peptide encompassing the 31-71 sequence retains full myostatin binding capacity and intramuscular injection of this peptide induces muscle hypertrophy in dystrophic mice. This direct interaction site between MSTN and DCN contains a conserved CX3CXCX6C pattern of class I SLRPs, whose cluster of cysteins and its interaction with zinc were shown to be crucial in the anti-MSTN activity of DCN. Various studies of the mechanism resulting of the sequestration of MSTN by DCN in ECM were conducted in order to explain the phenomenom observed in mice. Al last, we have studied the potential of DCN in the cellular transplantation and developped different anti-myostatin strategies of genetic therapy
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Piper, Tony Andrew. "A study of the transfer of recombinant dystrophin genes into skeletal muscle cells." Thesis, Royal Holloway, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286683.
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McArdle, Anne. "Mechanisms skeletal muscle damage in the dystrophin-deficient MDX mouse." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385144.
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