Navegando por Palavras-chave "Muscle, skeletal"

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    Análise da fadiga muscular localizada em atletas e sedentários através de parâmetros de freqüência do sinal eletromiográfico
    (Universidade Federal de São Paulo (UNIFESP), 2008-04-30) Santos, Marcelo Cláudio Amaral [UNIFESP]; Arida, Ricardo Mario [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Though the analysis in the frequency domain of the Electromyographic Signal (EMG) was used in the characterization of the localized muscular fatigue process their application, specifically the Median Frequency (MF), is rarely explored in the sports. The objective of this study was to verify the viability in the application of the EMG signal, through of the frequency domain analysis, as parameter for determination and differentiation of the behavior of located muscle fatigue. Two groups of subjects one characterized as athletes (n=12) and other as sedentary (n=12), were submitted to analysis based in procedures executed in three different experimental situations, all involving the isometric exercise modality: i) maximum test for determination of the Maximum Voluntary Isometric Contraction (MVIC); ii) fatigue test, 35 sec. sustained load of 80% of MVIC; iii) recovery test, 10 sec. sustained load of 80% of MVIC; where was monitored the behavior of MF in the first three (Fmedi) and last three seconds (Fmedf) of the EMG signal of anterior tibial muscle during the fatigue test. During the 10 seconds of the recovery test MF was calculated regarding the whole period (Fmedr) this parameter was used to calculate the Recuperation Muscle Index (RMI). The results showed that Fmedf presented a low value in relation to Fmedi in both groups (p <0.05). Also the value of Fmedi and Fmedf for the athlete group presented larger higher value in comparison with the sedentary group (p <0.05). The mean value and standard deviation of RMI for the athlete group were 62.1% ±28.7 and for sedentary group was 55.2% ±27.8 (p>0.05). In general terms the results presented in this study allow inferring the viability in the application of the frequency domain parameters of the EMG signal for the determination and differentiation of the located muscle fatigue behavior.
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    Efeito da Privação e da Restrição de sono sobre a densidade de receptores de andrógeno e de glicocorticóide no músculo esquelético
    (Universidade Federal de São Paulo (UNIFESP), 2010-07-15) Venancio, Daniel Paulino [UNIFESP]; Mello, Marco Tulio de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Aim: To investigate the effect of paradoxical sleep deprivation for 96 hours and sleep restriction for 21 days on the expression of glucocorticoid and androgens receptors in skeletal muscle gastrocnemius. Methods: Male rats of 3 months of age were distributed into 6 groups: experimental (control, deprived of sleep for 96 hours and paradoxical sleep rebound for 24 h, sleep restriction for 21 days, deprived of sleep for 96 hours treated with testosterone and paradoxical sleep-deprived treated with saline). The protocols submitted to sleep deprivation for 96 hours and sleep restriction for 21 days was the modified multiple platform method. At the end of this period, the animals were sacrificed and blood collected for testosterone and corticosterone measurement. The gastrocnemius muscle was dissected and processed for histology and immunohistochemistry, respectively and western blotting for receptor glucocorticoids. Results: Decrease of receptor immunoreactivity glucocorticoid and androgen receptor was not altered with periods of sleep deprivation study. We also observed that the sleep deprivation animals showed reduced cross section skeletal muscle. Furthermore, we observed reduced concentrations of testosterone and increased corticosterone concentration in all periods of sleep deprivation study. Conclusion: Paradoxical sleep deprivation for 96 hours and sleep restriction for 21 days led to subsensibilização of the glucocorticoid receptor and reduced muscle mass, causing atrophy of the gastrocnemius muscle.
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    Índice do número de unidades motoras (MUNIX) : aspectos técnicos e correlações clínicas em pacientes com esclerose lateral amiotrófica
    (Universidade Federal de São Paulo (UNIFESP), 2017-08-18) Bezerra, Marcio Luiz Escorcio [UNIFESP]; Manzano, Gilberto Mastrocola [UNIFESP]; Oliveira, Acary Souza Bulle [UNIFESP]; http://lattes.cnpq.br/3911841387107665; http://lattes.cnpq.br/1662881809387292; http://lattes.cnpq.br/4788464407515502; Universidade Federal de São Paulo (UNIFESP)
    Introdução: MUNIX é uma técnica neurofisiológica utilizada fundamentalmente para quantificar a perda de unidades motoras. Para tal fim, tem se mostrado eficaz e de utilização relativamente rápida. Devido à necessidade de marcadores de perda de neurônios motores inferiores (NMI) na Esclerose Lateral Amiotrófica (ELA), há crescente interesse pela técnica nos últimos anos. Objetivos: Estudar a reprodutibilidade intra-examinador do MUNIX em controles saudáveis e em pacientes com ELA e avaliar abordagens que possam levar a uma melhoria do método. Utilizar o MUNIX de maneira transversal e longitudinal em pacientes com ELA, com o intuito de detectar a perda de unidades motoras. Mais especificamente, estudar a capacidade do método para detecção da perda de unidades motoras em regiões corporais ainda clinicamente não afetadas. Métodos: Em um primeiro estudo foi avaliada a reprodutibilidade intra-examinador do método em indivíduos saudáveis e pacientes com ELA com duas aferições realizadas no mesmo dia. Adicionalmente, com os valores de referência extraídos dos controles, foram estabelecidos pontos de corte para o MUNIX em cada músculo e então avaliado se a técnica é capaz de separar pacientes com ELA dos controles saudáveis de maneira transversal. Em um segundo estudo, foi testada a reprodutibilidade de testes realizados com intervalo de três meses, primeiramente com uma medida isolada de MUNIX (S-MUNIX) e então com a média de três valores nas duas avaliações (M-MUNIX). Foram comparadas então as reprodutibilidades dessas duas abordagens. Em um terceiro estudo, foram recrutados pacientes com ELA, com o objetivo de incluir indivíduos com extremidades clinicamente não afetadas e avaliar como o M-MUNIX e o índice neurofisiológico (IN) se comportam nessas regiões corporais e se há queda dos índices com o seguimento longitudinal. Resultados: O primeiro estudo mostrou que a reprodutibilidade intra-examinador do MUNIX foi boa em 51 controles saudáveis e 30 pacientes com ELA, como demonstrado pelos valores dos coeficientes de correlação intraclasse (CCI) e pelos coeficientes de variação individual (CVi). Os valores do CVi, no entanto, foram mais elevados nos pacientes com ELA, principalmente o abdutor curto do polegar (ACP) que mostrou 24% de variabilidade individual. A análise da curva ROC, para distinguir indivíduos com a doença dos saudáveis, mostrou boa área sob a curva: 0,9504. No segundo estudo foram avaliados 21 controles saudáveis de acordo com o protocolo descrito. O M-MUNIX se mostrou mais reprodutível que o S-MUNIX nesses indivíduos. Houve uma melhora mais acentuada no CVi do que no CCI, de forma que a variabilidade individual passou a ficar abaixo de 10% em todos os músculos testados. No terceiro estudo foi demonstrado que o M-MUNIX, quando utilizado de maneira longitudinal, é capaz de detectar perda de unidades motoras precocemente em extremidades clinicamente não afetadas de pacientes com ELA. Essa queda se deu de maneira significativa nos parâmetros neurofisiológicos (M-MUNIX e IN), em contraste com os parâmetros clínicos, que tiveram queda apenas discreta durante os intervalo pré- sintomático. O M-MUNIX do músculo ACP foi o parâmetro afetado de forma mais precoce. Conclusão: A técnica teve boa performance diagnóstica e capacidade para diferenciar indivíduos saudáveis daqueles com ELA, de forma que possui o potencial para ser usado como instrumento de triagem para a detecção de músculos desnervados. O M-MUNIX se mostrou mais reprodutível e preciso do que a utilização de uma medida isolada do MUNIX, sendo portanto, uma abordagem recomendável em estudos longitudinais. O M-MUNIX e o IN foram capazes de detectar a perda de neurônios motores no seguimento de extremidades/membros clinicamente ainda não afetados de pacientes com ELA e foram mais sensíveis que os parâmetros clínicos para tal intuito. Dessa forma, a utilização dessas técnicas podem ser vantajosa em estudos clínicos que tenham como objetivo testar a eficácia de uma determinada droga, uma vez que uma ferramenta mais sensível pode ser especialmente relevante nos estágios iniciais da ELA.
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    Mecanismos celulares e moleculares da atrofia muscular induzida pela privação de andrógeno
    (Universidade Federal de São Paulo (UNIFESP), 2009-03-25) Oliveira, Marcelo Pires de [UNIFESP]; Godinho, Rosely Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Skeletal muscle fibers are multinucleated cells and each myonucleus controls gene expression in a defined cytoplasmic region, the nuclear domain (ND). Generally, muscle atrophy occurs with increased proteolysis by expression of specific ubiquitin ligases, such as atrogin-1, thus leading to loss of cytoplasm and ND remodeling. The neuromuscular junction (NMJ) is also remodeled by reduced functional load in the atrophied fiber. The levator ani muscle (LA) of the adult male rat is highly sensitive to androgens and atrophies with castration. Therefore, we investigated the effect of androgen deprivation on LA atrogin-1 expression, ND organization and NMJ remodeling. Fibers from LA or extensor digitorum longus muscle (EDL) were isolated from 4-month-old male Wistar rats, both normal controls or after castration for 2 to 90 days. Fibers were used for histochemical staining of acetylcholinesterase (AChE) or histofluorescent staining of nicotinic cholinoceptors (nAChR) and nuclei. Brightfield images or confocal z-series were acquired and fiber diameter, ND size, NMJ length and volume were measured. Atrogin-1 expression was evaluated by qRT-PCR and immunoblotting, and caspase 3 activity was assessed by a fluorimetric assay with Ac-DEVD-AMC substrate. Castration induced atrophy of LA, which reached 30% of control weight after 90 days. Atrogin-1 mRNA increased 31-fold after 2-day castration, returning to normal levels after 30 days, while atrogin-1 protein increased linearly up to 270% of control values after 30 days. Testosterone propionate treatment (4 mg/kg, sc) for just 24 h reduced atrogin-1 mRNA to control levels. Fiber diameter and nuclear domains decreased to 39% and 24% of control values after 60-day castration, respectively. Interestingly, castration did not change caspase 3 activity in LA. Castration progressively reduced NMJ length and volume to 65% and 54% of normal values after 90 days, respectively. No changes were seen in EDL up to 90-day castration. Castration-induced LA atrophy is accompanied by increased atrogin-1 and apoptosis throughout the fiber, without global caspase 3 activity increase. However, loss of nuclei is not enough to maintain cytoplasm/nucleus ratio (ND) in the atrophied fiber. LA atrophy occurs with NMJ shrinkage in length and volume, indicating a passive response of junctional ND to loss of cell volume and surface.
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    Treatment of Dyslipidemia with Statins and Physical Exercises: Recent Findings of Skeletal Muscle Responses
    (Sociedade Brasileira de Cardiologia - SBC, 2015-01-01) Bonfim, Mariana Rotta; Oliveira, Acary Souza Bulle [UNIFESP]; Amaral, Sandra Lia do; Monteiro, Henrique Luiz; Universidade Estadual Paulista (UNESP); Universidade Federal de São Paulo (UNIFESP)
    Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords “statin” AND “exercise” AND “muscle”, restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible.
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    Varredura fenotípica de nematoides C elegans mutantes para proteínas necessárias para a via de RNAi sistêmica
    (Universidade Federal de São Paulo (UNIFESP), 2017-05-30) Camara, Henrique [UNIFESP]; Mori, Marcelo Alves da Silva [UNIFESP]; http://lattes.cnpq.br/3425809117024031; http://lattes.cnpq.br/9774948524135567; Universidade Federal de São Paulo (UNIFESP)
    Background and objective: SIDs and RSDs are proteins required for double stranded RNA transport in C. elegans. The mutants for their coding genes have tissue specific systemic RNAi defects. SID-2 is important for the incorporation of RNA from the environment to the organism, without a role in the transport of endogenous RNAs. RSD-3, RSD-2 e RSD-6 are specific for the transport to the germline, althought rsd-2 and rsd-6 mutants shows RNAi defects in the intestine. SID-1, SID-3 e SID-5 transport RNA to all non-neuronal tissues. Some of these proteins are conserved in more complex organisms, including humans, and assist the gene silencing produced by mobile RNAs. The mechanisms through which SIDs and RSDs mediate RNA transport are well described, but little is known about their roles in worm physiology. Therefore, the present work was conducted to identify physiological roles of SIDs and RSDs. Methods: We assessed the lifespan and age-related muscular function decline, oxidative and heat stress resistance, time of development and fertility in worms lacking functional SIDs and RSDs. Results: Systemic RNAi deficient worms reached adulthood, but the developmental time was delayed in sid-2, rsd-2, sid-1, sid-5 and sid-3 mutants. Mutations that impair RNA transport to the germline, with exception of sid-1, reduced brood size. In contrast, impaired systemic RNAi in somatic tissues, but not in the germline, rendered worms short-lived. Interestingly, the median lifespan was inversely correlated with the number of RNAi deficient somatic tissues (e.g. N2 = rsd-3 >rsd-2 > sid-1). The reduction in lifespan of some sid and rsd mutants was accompanied by premature age-related muscular dysfunction , assessed by reduced spontaneous contraction of the pharynx and the body-wall muscle, and reduced oxidative and heat stress resistance. Conclusions: Collectively, our data demonstrate that SIDs and RSDs are necessary in the germline for proper fertility. In different somatic tissues, but notably in the intestine, these proteins are necessary for normal development, longevity and stress resistance. This indicates that mobile RNAs are physiologically used as signaling molecules to control organismal homeostasis. These results provide insights into novel mechanisms of intertissue communication in multicellular organisms.