Humberto Santo Neto

University of Campinas, Conceição de Campinas, São Paulo, Brazil

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Publications (70)115.63 Total impact

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    ABSTRACT: Duchenne muscular dystrophy (DMD) is a devastating inherited neuromuscular disorder with an incidence of 1 in 3500 live male births. DMD is characterized by a mutation in the X-chromosome that leads to a lack of dystrophin in skeletal and cardiac muscles. In DMD and in the mdx mice model of DMD, the absence of dystrophin leads to sarcolemma instability, increased calcium influx and consequent myonecrosis. Abnormal calcium entry and buffering seem to play important roles in dystrophy pathology and stretch activated calcium channels, such as the transient receptor potential canonical channel 1 (TRPC1), greatly contribute to calcium changes in dystrophic fibers. In this study we investigated the effects of suramin, an anti-fibrotic agent on TRPC1 levels in the diaphragm of mdx mice, at later stages of the disease (11 months). We also investigated the effects of suramin of the levels of calsequestrin, the main calcium-binding protein of the endoplasmic reticulum. Mdx mice (8 months old) received intraperitoneal injections of suramin (60 mg/kg body weight), twice a week for 3 months. Control mdx mice (8 months old) were injected with saline. Western blot analysis showed that suramin decreased the levels of TRPC1 (2.3±0.2 in control vs 1.3±0.3 in suramin-mdx, p<0.05) and improved the levels of calsequestrin (0.5±0.1 in control vs 0.9±0.2 in suramin-mdx, p<0.05). Suramin also decreased muscle fiber total calcium (29% decrease as observed with inductively coupled plasma-optical emission spectrometry). The present results suggest that suramin, in addition to its anti-fibrotic action can ameliorate dystrophy in the mdx diaphragm, at later stages of the disease, by acting on calcium entry (TRPC1) and calcium binding (calsequestrin) mechanisms.
    Neuroscience 2014, Washington; 11/2014
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    ABSTRACT: In Duchenne muscular dystrophy (DMD), lack of dystrophin leads to progressive skeletal muscle degeneration. Tumor necrosis factor-alpha (TNF-a) and transforming growth factor-beta (TGF-b) contribute to inflammation and fibrosis deposition and have been used as markers of dystrophy progression. Skeletal muscles are affected under different intensities, with the respiratory muscles being the most affected and some muscles, such as the intrinsic laryngeal, spared. We performed a comparative evaluation of dystrophy progression in the dystrophic diaphragm (DIA) and quadriceps (QDR) muscles in the mdx mice model of DMD. We used mdx and C57BL/10 (control) mice. We assessed their histopathological features (morphometric analysis) and molecular composition (TNF-a and TGF-b levels by Western blot) at ages 1, 4 and 9 months. Fibrosis was the main histopathological feature in mdx DIA, which increased over time (1 month: 1.8%, 4 months: 18.2%, 9 months: 32% of fibrosis), being significantly elevated in mdx DIA compared to mdx QDR (9 months: 9% of fibrosis). Conversely, muscle regeneration, as demonstrated by areas with centrally nucleated fibers, was the main feature of the mdx QDR (1 month: 10%, 4 months: 79%, 9 months: 90% of centrally nucleated fibers areas) and significantly elevated in comparison to mdx DIA (9 months: 66% of central nucleated areas). Inflammation-regeneration area was higher in QDR at 1 month (50% in QDR vs. 6.0% in DIA), reaching similar levels (about 3%) in both muscles, at 9 months. Mdx DIA presented higher levels of TNF-a and TGF-b compared to mdx QDR, from 4 months on. In mdx QDR, the levels of TNF-a and TGF-b were increased (compared to control) during dystrophy progression. Elevated levels of TNF-a and TGF-b correlated with dystrophy progression mainly in mdx DIA. We draw attention to the extensive regeneration in mdx QDR concomitantly to elevated levels of proinflammatory and profibrotic cytokines.
    43nd European Muscle Conference, Salzburg; 09/2014
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    ABSTRACT: Introduction: The purpose of this study was to better understand the beneficial effects of doxycycline on the dystrophic muscles of the mdx mouse. Methods: Doxycycline (DOX) was administered for 36 days, starting on postnatal day 0, via drinking water. Untreated mdx mice received plain water for the same period and served as a control group. Results: DOX decreased the levels of metalloproteinase-9 and tumor necrosis factor alpha in the biceps brachii and diaphragm of the mdx mice. It also reduced the total amount of calcium in the muscles studied, concomitant with an increase in the levels of calsequestrin 1. Discussion: These results show that DOX can affect factors that are important in the dystrophic pathogenesis and highlight its potential to be a readily accessible therapy for clinical trials for treatment of Duchenne muscular dystrophy. © 2014 Wiley Periodicals, Inc.
    Muscle & Nerve 08/2014; 50(2). DOI:10.1002/mus.24177 · 2.31 Impact Factor
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    ABSTRACT: Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease that causes respiratory failure that results in death at about 30 years of age. The lack of dystrophin in mdx mice, the experimental model of DMD, causes sarcolemma breakdown and increased calcium influx followed by necrosis and fibrosis. At later stages of disease, cardiac muscle is also affected and the dystrophic cardiomyopathy is characterized by cardiomyocyte hypertrophy, necrosis, myocardial fibrosis and ECG abnormalities. Previously, we demonstrated that suramin, an antifibrotic agent and purinergic P2 receptor antagonist, decreased fibrosis and improved cardiac function in mdx mice. In this study we add further information about the effects of suramin on cardiac muscle total calcium and on β-dystroglycan, a main component of the dystrophin-protein complex. Mdx mice (n=18; 8 months old) received intraperitoneal injections of suramin (60 mg/kg body weight), twice a week for 3 months. Control mdx mice (n=18; 8 months old) were injected with saline. Blood was obtained to determine cardiac creatine-kinase (CK-cardiac). Suramin decreased (61%) the total amount of cardiac calcium (determined by inductively coupled plasma-optical emission spectrometry) and there was a tendency to suramin to increase β-dystroglycan levels (12.5±3% in control vs. 13.7±2.7% in suramin-mdx). Western blot analysis showed that suramin decreased the levels of the transient receptor potential canonical channel 1 (3.1±0.1% in control vs. 2.4±0.3% in suramin-mdx, p<0.05), a component of the stretch-activated calcium channel. Concomitantly, suramin decreased (57%) cardiac-CK and cardiac troponin (7.8±3.8% in control vs. 3.4±1.5% in suramin-mdx, p<0.05). Overall, we demonstrate that suramin decreases cardiomyocyte necrosis, possibly by its ability to affect cardiac muscle total calcium and a calcium channel-related protein. Furthermore, suramin may have potential benefits in maintaining the structure of the dystrophin-protein complex
    2013 Annual Meeting of the American Society for Cell Biology; 12/2013
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    ABSTRACT: Introduction: To evaluate the effects of suramin, an antifibrotic agent, on the cardiac function and remodeling in the mdx mice. Methods: mdx mice (8 months old) received intraperitoneal injections of suramin twice a week for 3 months. Control mdx mice (8 months old) were injected with saline. Results: Suramin improved the electrocardiography profile with main corrections seen in S/R wave ratio, PR interval, Q amplitude with a significant decrease in the cardiomyopathy index. Suramin decreased myocardial fibrosis, inflammation, and myonecrosis. Discussion - These findings suggest that the antifibrotic drug suramin may be a potential new adjunctive therapy to help improve cardiomyopathy in DMD. © 2013 Wiley Periodicals, Inc.
    Muscle & Nerve 12/2013; 48(6). DOI:10.1002/mus.23858 · 2.31 Impact Factor
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    ABSTRACT: Duchenne Muscular Dystrophy (DMD) is a myopathy characterized by absence of dystrophin protein which causes functional changes followed by necrosis of skeletal and cardiac muscle fibers. Cardiomyopathy is the main cause of death due to progressive myocardial fibrosis (MF). Therefore, treatments that prevent myonecrosis and progression of MF are important in patients with DMD. The mdx mouse also features progressive MF and it has served as an experimental model of cardiomyopathy in DMD. The aim of this study was to evaluate the treatment effect of the drug pifithrin-alpha (PFT-α) on the processes of muscle cell necrosis and MF. The mdx mice (n = 28) with eight months of age was used, divided into two experimental groups: mdx PFT-α (n = 14) and mdx control group (n = 14). Also C57BL/10 animals were used (n = 14) for untreated mdx control animals. The animals of PFT-α mdx group received doses of 2.2 mg / kg by intraperitoneal injections twice a week for fifteen weeks. The animals were euthanized and the heart was collected and frozen for quantitative analysis of proteins MMP-2, TGF-β1, TNF and NF-kB through the technique of western blotting. Blood was collected and subjected to analysis of the total and cardiac enzyme creatine kinase (CK). Treatment with PFT- α reduced levels of pro-inflammatory proteins MMP-2 (23%), TGF-β1 (60%), TNF (36%) and NF-kB (30%) of the mdx PFT-α group compared to the untreated mdx control group. Also there were decreased levels of total and cardiac CK in the blood plasma of the mdx PFT-α group compared to the untreated mdx control group. It is concluded that treatment with PFT-α was effective in reducing the pro-inflammatory proteins and may prevent or ameliorate the development of MF.
    Neuroscience 2013; 11/2013
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    ABSTRACT: Muscle degeneration and fibrosis are associated with inflammation in dystrophic muscles of Duchenne muscular dystrophy (DMD) and in the mdx mice, a model of DMD. Corticosteroids including deflazacort (DFZ) are still the gold standard therapy for DMD, in spite of the relevant side effects. Combined drug interventions may be one therapeutic strategy for complex diseases such as DMD. We evaluated, in mdx mice, the effect of a combined treatment of DFZ with doxycycline (DOX), a potent inhibitor of matrix metalloproteinases (MMP), on the some biomarkers involved in the pathogenesis of muscular dystrophy. DFZ (1.2mg/kg) and DOX (6mg/ml) were administered either alone or in combination to mothers and newborns in drinking water, for 36 days (starting on postnatal day 0). Effects were assessed in vivo and ex vivo functional properties, histological and biochemical parameters. Biceps brachii (BB) and diaphragm (DIA) muscles were removed. Histological analysis showed that each treatment significantly attenuated myonecrosis and reduced inflammation in BB and DIA, a marked complementary effect was observed with the combination DFZ/DOX. Both drugs significantly decreased blood creatine kinase levels, however the benefit was greater for the DFZ/DOX therapy. Total calcium content was significantly higher in mdx muscles than in control C57Bl/10. Western blot analysis showed higher levels of MMP-9 and Tumor Necrosis Factor-α (TNF-α) in mdx muscles compared to control C57Bl/10 mice. In the DFZ/DOX group the MMP- 9 expression was reduced 82% in BB (1,53± 0.35 vs 0,27±0.49) and 75% in DIA (5,06±1.41 vs 1,29±0.71) and TNF-α decreased respectively 64% and 79% compared to untreated mdx group. Compared to untreated mdx mice the calsequestrin (CSQ1) expression in all treated groups exhibited a significant increase in BB and DIA. The effect of therapy either alone or in combination was the partial restoration of CSQ1 expression levels reaching those levels found in non dystrophic muscles. In vivo, each treatment significantly increased forelimb strength and decreased fatigue compared to that mdx mice. These results indicate that combined DFZ/DOX may be a possible useful therapeutic alternative to ameliorate muscular dystrophy caused by dystrophin deficiency.
    Neuroscience 2013, San Diego; 11/2013
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    ABSTRACT: We examined whether diaphragm degeneration affects cardiac muscle in dystrophin-deficient mdx mice. To worsen diaphragm degeneration, adult mdx mice were exercised (swim) for 1 h, 5 days a week, for 2 months. One day after the last exercise, diaphragm and hearts were analyzed by histopathology and western blot of metalloproteinase (MMP) and tumor growth factor (TGF)-beta. Age matched unexercised mdx served as controls. In mdx diaphragm, exercise increased fibrosis (60 %) and the levels of active MMP-2, pre MMP-2 and pro MMP-2 (26, 28 and 12 % increase). In mdx heart, exercise also lead to increased fibrosis (42 % higher than unexercised), higher levels of TGF-b and of active MMP-2, pre MMP-2 and pro MMP-2 (32, 28 and 11 % increase) compared with unexercised mdx. Density of inflammatory cells patches was almost twice higher in exercised than unexercised mdx hearts. Right ventricle was significantly more affected than the left ventricle: myocardial fibrosis was increased by 45 % (8.3 ± 0.6 in unexercised vs. 12.0 ± 0.6 in exercised) in the right ventricle while in the left ventricle this increase was 35 % (5.6 ± 0.7 unexercised vs. 7.6 ± 0.8 exercised). Inflammatory cells/ degenerating cardiomyocytes density was increased 95 % (2.3 ± 0.6 unexercised vs. 4.5 ± 0.8 in exercised) in the right ventricle against 71 % increase in left ventricle (1.4 ± 0.6 unexercised vs. 2.4 ± 0.5 exercised). While exercise promoted concomitant changes in the dystrophic diaphragm and heart, the present results suggest that degeneration of diaphragm may contribute, at least in part, to the cardiac injury in dystrophin deficient mice.
    42nd Europe Muscle Conference, Amsterdam; 09/2013
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    ABSTRACT: We examined whether diaphragm degeneration affects cardiac muscle in dystrophin-deficient mdx mice. To worsen diaphragm degeneration, adult mdx mice were exercised (swim) for 1 hour, 5 days a week, for 2 months. One day after the last exercise, diaphragm and hearts were analyzed by histopathology an western blot of metalloproteinase (MMP) and tumor growth factor (TGF-beta). Age matched unexercised mdx served as controls. In mdx diaphragm, exercise increased fibrosis (60%) an the levels of active-MMP-2, pre-MMP-2 and pro-MMP-2 (26%, 28% and 12% increase). In mdx heart, exercise also lead to increase fibrosis (42% higher than unexercised), higher levels of TGF-b and of active-MMP-2, pre-MMP-2 and pro-MMP-2 (32%, 28% and 11% increase) compared with unexercised mdx. Density of inflammatory cells patches was almost twice higher in exercised than unexercised mdx hearts. Right ventricle was significantly more affected than the left ventricle: myocardial fibrosis was increases by 45% (8.3±0.6 in unexercised vs. 12±0.6 in exercised) in the right ventricle while in the left ventricle this increase was 35% (5.6±0.7 unexercised vs. 7.6±0.8 exercised). Inflammatory cells/degenerating cardiomyocytes density was increased 95% (2.3±0.6 unexercised vs. 4.5±0.8 in exercised) in the right ventricle against 71% increase in left ventricle (1.4±0.6 unexercised vs. 2.4±0.5 exercised). while exercise protocol promoted concomitant changes in the dystrophic diaphragm and heart, the present results suggest that degeneration of diaphragm may contribute, at least in part, to the cardiac injury in dystrophin deficient mice.
    42nd European Muscle Conference, Amsterdam; 09/2013
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    ABSTRACT: In dystrophic mdx mice and in Duchenne muscular dystrophy, inflammation contributes to myonecrosis. Previously, we demonstrated that eicosapentaenoic acid (EPA) decreased inflammation and necrosis in dystrophic muscle. In the present study, we examined the effects of EPA and the corticoid deflazacort (DFZ) as modulators of M1 (iNOS-expressing cells) and M2 (CD206-expressing cells) macrophages. Mdx mice (14days old) received EPA or DFZ for 16days. The diaphragm, biceps brachii and quadriceps muscles were studied. Immunofluorescence, immunoblotting and ELISA assays showed that EPA increased interleucin-10, reduced interferon-γ and was more effective than DFZ in promoting a shift from M1 to M2.
    Journal of neuroimmunology 09/2013; DOI:10.1016/j.jneuroim.2013.09.007 · 2.79 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin leads to muscle degeneration and inflammation contributes to progression of the disease. In this study, we evaluated the effects of commercially available fish oil containing EPA and docosahexaenoic acid (DHA) on mdx. METHODS: Mdx mice (14 days old) were treated with fish oil (FDC Vitamins; 0.002 g EPA and 0.001 g DHA) for 16 days by gavage. Control mdx mice received mineral oil (Nujol). Grip strength measurement was used for functional evaluation. The sternomastoid, diaphragm and biceps brachii muscles were removed and processed for histopathology and Western blot analysis. RESULTS: Fish oil decreased creatine kinase and myonecrosis. In all muscles studied, the inflammatory area was significantly reduced after treatment (18.0 ± 3.0% inflammatory area in untreated mdx mice versus 4.0 ± 1% in treated mdx mice). Fish oil protected against the loss of muscle strength. Fish oil significantly reduced the levels of TNF-α and the levels of 4-HNE-protein adducts (30-34% reduction for both) in all muscles studied. CONCLUSIONS: Commercially available fish oil may be potentially useful to ameliorate dystrophic progression of skeletal muscles, deserving further clinical trials in DMD patients.
    Clinical nutrition (Edinburgh, Scotland) 11/2012; 32(4). DOI:10.1016/j.clnu.2012.11.013 · 3.94 Impact Factor
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    ABSTRACT: Introduction: In Duchenne muscular dystrophy and in the mdx mouse, muscle fiber degeneration and subsequent fibrosis lead to cardiorespiratory failure. Previously, we demonstrated that the anti-fibrotic agent suramin was effective in decreasing fibrosis in mdx muscles. In this study, we were interested to see whether suramin could affect metalloproteinases (MMP) and improve the functional activity of the mdx diaphragm muscle. Methods: Zymography was performed to evaluate MMP-2 and MMP-9 activity. Western blotting was used to analyze the levels of beta-dystroglycan. Muscle function was assessed in hemidiaphragm in vitro preparations. Results: We found that suramin affects metalloproteinase-9 activity and increases beta-dystroglycan. Furthermore, suramin also protects against diaphragm muscle fatigue over time. Conclusions: These results show the potential benefits of suramin in maintaining the structure of the dystrophin-glycoprotein complex. Muscle Nerve, 46:810-813, 2012.
    Muscle & Nerve 11/2012; 46(5):810-3. DOI:10.1002/mus.23468 · 2.31 Impact Factor
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    ABSTRACT: A fibrose e as alterações eletrocardiográficas são características patológicas observadas no coração de pacientes com Distrofia Muscular de Duchenne (DMD) e no camundongo mdx, modelo da DMD. Objetivamos correlacionar a fibrose cardíaca com a mudança temporal nos parâmetros eletrocardiográficos e o nível da citocina pró-fibrótica (TGF-b1) na evolução da cardiomiopatia em camundongos mdx. Foram utilizados camundongos mdx de ambos os sexos, com idades de 11, 13 e 17 meses. A avaliação funcional foi realizada in vivo com eletrocardiógrafo na derivação DII. O músculo cardíaco foi dissecado para análise histopatológica com tricrômico de Masson e os níveis de TGF-b1 foram avaliados por Western blot. A análise histopatológica mostrou aumento progressivo da fibrose miocárdica com a idade. Aos 17 meses a fibrose cardíaca alcançou 13,1±3,9% um aumento significativo com as demais idades (mdx-11 meses 6,1±1,0%; mdx-13 meses 8,6±1,2%, p<0.05 ANOVA). Os níveis de TGF-b1 estão aumentados nos estágios intermediários da cardiomiopatia, atingindo um pico aos 13 meses (3,0±0,7%) seguido de redução significativa aos 17 meses (1,8±0,3%, p<0.01 ANOVA). Os parâmetros eletrocardiográficos revelaram comprometimento da condução do impulso elétrico no coração distrófico com a progressão da fibrose. O índice de cardiomiopatia dado pela razão dos intervalos QT/PQ foi maior aos 17 meses (1,5±0,1), um aumento de 79% e 48% comparados com as idades de 11 e 13 meses respectivamente (p<0.01 ANOVA). O traçado eletrocardiográfico demonstrou prolongamento do intervalo QRS, aprofundamento da onda Q e intervalo PR encurtado, em todas as idades. A fibrose miocárdica e as alterações eletrocardiográficas estão associadas com a evolução da cardiomiopatia em camundongos mdx. Os níveis de TGF-b1 podem não estar relacionados com a progressão temporal da fibrose.
    XXV Congresso Brasileiro de Anatomia 2012; 10/2012
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    ABSTRACT: We examined whether doxycycline, an antibiotic member of the tetracycline family, improves the histopathology and muscle function in mdx mice, the experimental model of DMD. Doxycycline was administered for 36 days (starting on postnatal day 0) and for 9 months (starting at 8 months of age) in drinking water. Histopathological, biochemical (creatine kinase), and functional (forelimb muscle grip strength) parameters were evaluated in limb, diaphragm, and cardiac muscle. Doxycycline significantly minimized the dystrophic phenotype of skeletal and cardiac muscles and improved forelimb muscle strength. The drug protected muscle fibers against myonecrosis and reduced inflammation. Furthermore, it slowed the progression of myocardial fibrosis. This study provides evidence that doxycycline may be a potential therapeutic agent for DMD.
    Muscle & Nerve 09/2012; 46(3):400-6. DOI:10.1002/mus.23331 · 2.31 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: Duchenne muscular dystrophy (DMD) is a genetic muscle disease caused by the absence of dystrophin. An established animal model of DMD is the mdx mouse, which is unable to express dystrophin. Inflammation, particularly the proinflammatory cytokine tumor necrosis factor alpha (TNF-α), strongly contributes to necrosis in the dystrophin-deficient fibers of the mdx mice and in DMD. In this study we investigated whether the antioxidant N-acetylcysteine (NAC) decreases TNF-α levels and protects the diaphragm muscle of mdx mice against necrosis. METHODS: Mdx mice (14 days old) received daily intraperitoneal injections of NAC for 14 days, followed by removal of the diaphragm muscle. Control mdx mice were injected with saline. RESULTS: NAC reduced TNF-α and 4-HNE-protein adducts levels, inflammation, creatine kinase levels, and myonecrosis in diaphragm muscle. CONCLUSIONS: NAC may be used as a complementary treatment for dystrophinopathies. However, clinical trials are needed to determine the appropriate dose for patients with Duchenne muscular dystrophy.
    Clinical nutrition (Edinburgh, Scotland) 06/2012; 32(3). DOI:10.1016/j.clnu.2012.06.001 · 3.94 Impact Factor
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    ABSTRACT: Oxidative stress contributes to myonecrosis in the dystrophin-deficient fibers of mdx mice and in Duchenne's muscular dystrophy. We examined the effects of ascorbic acid (AA), an antioxidant and free radical scavenger, on the dystrophic diaphragm muscle. Mdx mice (14 d old) received AA for 14 d. Control mdx mice received saline. The muscle damage was visualized by the penetration of Evans blue dye into myofibers and the extent of inflammation was assessed by histologic analysis. Creatine kinase levels were measured for the biochemical evaluation of muscle fiber degeneration. The levels of tumor necrosis factor-α (a proinflammatory cytokine) and 4-hydroxynonenal (a marker of lipid peroxidation) were analyzed by immunoblotting. Ascorbic acid decreased creatine kinase levels, myonecrosis, inflammation, and the levels of tumor necrosis factor-α and 4-hydroxynonenal. The present results suggest that AA plays a protective role in dystrophic muscle degeneration, possibly by decreasing reactive oxygen species, and support further investigations of AA as a potential therapy for dystrophinopathies.
    Nutrition 12/2011; 28(6):686-90. DOI:10.1016/j.nut.2011.09.013 · 3.05 Impact Factor
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    ABSTRACT: In this study we investigate whether dystrophic intrinsic laryngeal muscles (ILM) from aged mdx mice show alterations in dystrophin-glycoprotein complex (DGC) components.Immunofluorescence and immunoblotting analyses of beta-sarcoglycan, beta-dystroglycan, and utrophin showed that aged ILM had a similar pattern of changes in aged affected muscles (diaphragm and limb), suggesting that aging leads to changes in utrophin and DGC proteins in dystrophic ILM that cannot be correlated with their protection from dystrophic change.
    Muscle & Nerve 12/2011; 44(6):978-80. DOI:10.1002/mus.22235 · 2.31 Impact Factor
  • Neuromuscular Disorders 10/2011; 21(9):710-710. DOI:10.1016/j.nmd.2011.06.986 · 3.13 Impact Factor
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    ABSTRACT: In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin is related to enhanced calcium influx and muscle degeneration. Stretch-activated channels (SACs) might be directly involved in the pathology of DMD, and transient receptor potential cation channels have been proposed as likely candidates of SACs. We investigated the levels of transient receptor potential canonical channel 1 (TRPC1) and the effects of streptomycin, a SAC blocker, in muscles showing different degrees of the dystrophic phenotype. Mdx mice (18 days old, n = 16) received daily intraperitoneal injections of streptomycin (182 mg/kg body wt) for 18 days, followed by removal of the diaphragm, sternomastoid (STN), biceps brachii, and tibialis anterior muscles. Control mdx mice (n = 37) were injected with saline. Western blot analysis showed higher levels of TRPC1 in diaphragm muscle compared with STN and limb muscles. Streptomycin reduced creatine kinase and prevented exercise-induced increases of total calcium and Evans blue dye uptake in diaphragm and in STN muscles. It is suggested that different levels of the stretch-activated calcium channel protein TRPC1 may contribute to the different degrees of the dystrophic phenotype seen in mdx mice. Early treatment designed to regulate the activity of these channels may ameliorate the progression of dystrophy in the most affected muscle, the diaphragm.
    AJP Cell Physiology 09/2011; 301(6):C1344-50. DOI:10.1152/ajpcell.00056.2011 · 3.67 Impact Factor
  • XXVI Reunião Anual da Federação de Sociedades de Biologia Experimental (FeSBE); 08/2011