1000 resultados para Atividade elétrica


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CONTEXTUALIZAÇÃO:O manuseio de materiais está ainda presente nos setores industriais e é associado a lesões na coluna lombar e membros superiores. A inserção de alças em caixas industriais é uma forma de reduzir os riscos relacionados à tarefa, porém a posição e a angulação das alças, que são fatores importantes para o conforto e segurança durante o manuseio, são ainda pouco investigadas objetivamente.OBJETIVOS:Comparar o manuseio de uma caixa comercial e de protótipos com alças e avaliar seus efeitos na postura de membros superiores, atividade elétrica muscular e percepção de agradabilidade em diferentes empunhaduras durante manuseio entre diferentes alturas.MÉTODO:Trinta e sete voluntários saudáveis avaliaram as alças dos protótipos que possibilitavam mudança nas posições (superior e inferior) e angulações (0°, 15° e 30º). Os movimentos dos punhos, cotovelos e ombros foram avaliados por meio da eletrogoniometria e inclinometria. A atividade elétrica muscular dos extensores do punho, bíceps braquial e porção superior do trapézio foi avaliada por um eletromiógrafo portátil. Os registros de movimento e atividade elétrica muscular foram sincronizados. Aspectos subjetivos de agradabilidade foram avaliados por meio de uma escala visual analógica.RESULTADOS E CONCLUSÕES:Os protótipos com alças inclinadas em 30° apresentaram as melhores avaliações de agradabilidade, posturas mais neutras de punho, menores níveis de atividade eletromiográfica do trapézio superior e menores ângulos de elevação dos braços. Os diferentes métodos de medida se mostraram complementares para a avaliação dos membros superiores durante as tarefas de manuseio.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Este trabalho tem como objetivo documentar as atividades realizadas no Estágio Curricular Obrigatório do curso de Graduação em Física Médica, realizado no Laboratório de Farmacologia da Junção Neuromuscular do Departamento de Farmacologia do Instituto de Biociências da UNESP de Botucatu. O estágio englobou atividades relacionadas à Instrumentação e à Iniciação Científica, ambas visando ao estudo da Farmacologia da Transmissão Neuromuscular. Desta forma, neste relatório serão apresentados, inicialmente, uma breve revisão dos aspectos fundamentais da morfologia e da fisiologia da junção neuromuscular. Posteriormente, serão descritos os métodos de estudo da transmissão neuromuscular aprendidos no decorrer do estágio, especificamente, as técnicas miográfica, que permite o registro da contração muscular, e eletrofisiológica, que possibilita o registro de atividade elétrica celular, ambas in vitro. Finalizando, serão apresentados os resultados do Projeto de Iniciação Científica desenvolvido, cujo objetivo foi estudar a ação do extrato etanólico da planta Tabernaemontana catharinensis sobre o bloqueio neuromuscular induzido por toxinas ofídicas na preparação do nervo frênico-músculo diafragma isolado de camundongos

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The electrocardiogram (ECG) is an important tool used in the diagnosis of cardiac arrhythmias, since it gives the graphic representation of depolarization and repolarization processes of the cardiac muscle. This study allows recording the electrical activity of myocardial cells and the underlying differences in electric potential: the magnitude of this difference is measured in millivolts (mV), and its duration is measured in seconds. The ECG is indicated when an irregular rhythm is detected during physical examination, such as bradycardias, tachycardias or arrhythmias that are not secondary to breathing, in animals with a history of syncope or weakness, for monitoring the effectiveness of antiarrhythmic therapy, in cases of putative pleural or pericardial effusion, and also in systemic diseases that lead to arrhythmia. For a reliable assessment, the ECG must be evaluated in conjunction with findings from the physical examination and clinical signs of each patient.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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OBJECTIVE: The hippocampus has an important role in the acquisition and recall of aversive memories. The objective of this study was to investigate the relationship among hippocampal rhythms. METHODS: Microeletrodes arrays were implanted in the hippocampus of Wistar rats. The animals were trained and tested in a contextual fear conditioning task. The training consisted in applying shocks in the legs. The memory test was performed 1 day (recent memory) or 18 days (remote memory) after training. We proposed a measure based on the FFT power spectrum, denominated "delta-theta ratio", to characterize the different behaviors (active exploration and freezing) and the memories types. RESULTS: The delta-theta ratio was able to distinguish recent and remote memories. In this study, the ratio for the 18-day group was smaller than for the 1-day group. Moreover, this measure was useful to distinguish the different behavior states active exploration and freezing. CONCLUSIONS: The results suggest delta-theta oscillations could reflect the demands on information processing during recent and remote memory recalls.

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OBJETIVO: Caracterizar o controle motor dos músculos masseter e temporal e a morfologia do músculo masseter em atividades da função mastigatória em indivíduos com oclusão normal; verificar a compatibilidade entre os exames de eletromiografia de superfície (EMGs) e ultrassonografia (USG). MÉTODOS: Participaram 22 indivíduos adultos, de ambos os gêneros, sem alterações no sistema miofuncional orofacial. Os procedimentos adotados para avaliação dos participantes foram: EMGs dos músculos masseteres (MM) e temporais (MT); e USG dos MM, na realização de três tarefas - repouso muscular, apertamento dentário com algodão, apertamento dentário sem algodão. RESULTADOS: Para análise estatística dos dados foram utilizados os testes de Kolmogorv-Smirnov, teste-T pareado e Correlação de Spearman, com nível de significância de 5%. Na EMGs observou-se diferença entre a ativação de MM e MT no apertamento dentário com e sem algodão, sendo MT mais ativo que MM em ambas as tarefas. Não foram observadas diferenças entre as hemifaces, tanto na EMGs quanto na USG. Observou-se também correlação positiva entre os exames na condição de apertamento dentário sem algodão esquerdo e na condição de apertamento dentário esquerdo com algodão, e tendência à significância no apertamento dentário direito sem algodão. CONCLUSÃO: A associação da EMGs e USG na investigação da funcionalidade muscular traz importantes informações sobre fisiologia da musculatura esquelética. Os resultados do presente estudo indicam haver correlação entre a EMGs e a USG, ou seja, o aumento da atividade elétrica e o aumento correspondente da espessura do músculo.

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Theta rhythm consists of an electrophysiological hippocampal oscillation present in mammalian species (4-12 Hz with variations across species). This oscillation is present during active waking and is also prevalent in local field potentials (LFP) during rapid eye movement sleep (REM sleep). Several studies have shown that theta rhythm is important in cognitive tasks and that the medial septum is a key region for its occurrence. The septum sends cholinergic, GABAergic and glutamatergic projections to the hippocampus, which in turn projects axons to the septum. Besides the septum, other regions are involved in regulating theta rhythm, forming a complex network of interactions among brain areas that result in theta rhythm. Optogenetics is a recently developed method that has been widely used in various research areas. It allows us to manipulate the electrical activity of neurons through light stimulation. One of the existing techniques consists in using a viral vector to induce the neuronal expression of ion channels associated with the light-sensitive molecule rhodopsin (e.g. ChR2). Once infected, the neurons become sensitive to light of a particular wavelength. The present M. Sc. research aimed to perform luminous stimulation of the brain in anesthetized and freely behaving animals using chronically implanted electrodes and optical fibers in animals infected with a viral vector for ChR2 expression. Surgical viral injections were performed in the medial septum; histological results confirmed the expression of ChR2 by way of the presence of the eYFP reporter protein in the septum and also in hippocampal processes. Moreover, we performed acute experiments with luminous stimulation of the medial septum and LFP recordings of the septum and hippocampus of anesthetized animals. Action potentials were recorded in the septum. In these experiments we observed a significant increase in the firing rates of septal neurons during luminous stimulation (n = 300 trials). Furthermore, we found an early light-evoked response in the hippocampal LFP. Chronic experiments with luminous stimulation of the medial septum and hippocampus in freely behaving animals were also performed in combination with LFP recordings. We found that the luminous stimulation of the septum is able to induce theta rhythm in the hippocampus. Together, the results demonstrate that the luminous stimulation of the medial septum in optogenetically-modified animals causes relevant electrophysiological changes in the septum and the hippocampus.

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Background: The inspiratory muscle training (IMT) has been considered an option in reversing or preventing decrease in respiratory muscle strength, however, little is known about the adaptations of these muscles arising from the training with charge. Objectives: To investigate the effect of IMT on the diaphragmatic muscle strength and function neural and structural adjustment of diaphragm in sedentary young people, compare the effects of low intensity IMT with moderate intensity IMT on the thickness, mobility and electrical activity of diaphragm and in inspiratory muscles strength and establish a protocol for conducting a systematic review to evaluate the effects of respiratory muscle training in children and adults with neuromuscular diseases. Materials and Methods: A randomized, double-blind, parallel-group, controlled trial, sample of 28 healthy, both sexes, and sedentary young people, divided into two groups: 14 in the low load training group (G10%) and 14 in the moderate load training group (G55%). The volunteers performed for 9 weeks a home IMT protocol with POWERbreathe®. The G55% trained with 55% of maximal inspiratory pressure (MIP) and the G10% used a charge of 10% of MIP. The training was conducted in sessions of 30 repetitions, twice a day, six days per week. Every two weeks was evaluated MIP and adjusted the load. Volunteers were submitted by ultrasound, surface electromyography, spirometry and manometer before and after IMT. Data were analyzed by SPSS 20.0. Were performed Student's t-test for paired samples to compare diaphragmatic thickness, MIP and MEP before and after IMT protocol and Wilcoxon to compare the RMS (root mean square) and median frequency (MedF) values also before and after training protocol. They were then performed the Student t test for independent samples to compare mobility and diaphragm thickness, MIP and MEP between two groups and the Mann-Whitney test to compare the RMS and MedF values also between the two groups. Parallel to experimental study, we developed a protocol with support from the Cochrane Collaboration on IMT in people with neuromuscular diseases. Results: There was, in both groups, increased inspiratory muscle strength (P <0.05) and expiratory in G10% (P = 0.009) increase in RMS and thickness of relaxed muscle in G55% (P = 0.005; P = 0.026) and there was no change in the MedF (P> 0.05). The comparison between two groups showed a difference in RMS (P = 0.04) and no difference in diaphragm thickness and diaphragm mobility and respiratory muscle strength. Conclusions: It was identified increased neural activity and diagrammatic structure with consequent increase in respiratory muscle strength after the IMT with moderate load. IMT with load of 10% of MIP cannot be considered as a placebo dose, it increases the inspiratory muscle strength and IMT with moderate intensity is able to enhance the recruitment of muscle fibers of diaphragm and promote their hypertrophy. The protocol for carrying out the systematic review published in The Cochrane Library.

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The human brain stores, integrates, and transmits information recurring to millions of neurons, interconnected by countless synapses. Though neurons communicate through chemical signaling, information is coded and conducted in the form of electrical signals. Neuroelectrophysiology focus on the study of this type of signaling. Both intra and extracellular approaches are used in research, but none holds as much potential in high-throughput screening and drug discovery, as extracellular recordings using multielectrode arrays (MEAs). MEAs measure neuronal activity, both in vitro and in vivo. Their key advantage is the capability to record electrical activity at multiple sites simultaneously. Alzheimer’s disease (AD) is the most common neurodegenerative disease and one of the leading causes of death worldwide. It is characterized by neurofibrillar tangles and aggregates of amyloid-β (Aβ) peptides, which lead to the loss of synapses and ultimately neuronal death. Currently, there is no cure and the drugs available can only delay its progression. In vitro MEA assays enable rapid screening of neuroprotective and neuroharming compounds. Therefore, MEA recordings are of great use in both AD basic and clinical research. The main aim of this thesis was to optimize the formation of SH-SY5Y neuronal networks on MEAs. These can be extremely useful for facilities that do not have access to primary neuronal cultures, but can also save resources and facilitate obtaining faster high-throughput results to those that do. Adhesion-mediating compounds proved to impact cell morphology, viability and exhibition of spontaneous electrical activity. Moreover, SH-SY5Y cells were successfully differentiated and demonstrated acute effects on neuronal function after Aβ addition. This effect on electrical signaling was dependent on Aβ oligomers concentration. The results here presented allow us to conclude that the SH-SY5Y cell line can be successfully differentiated in properly coated MEAs and be used for assessing acute Aβ effects on neuronal signaling.

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O eletrocardiograma é um registro da atividade elétrica do coração. É um exame importante na avaliação de doenças cardíacas e arritmias. É simples e fácil de fazer, mas deve ser realizado de forma adequada para a obtenção de um traçado sem interferências e possibilitar uma interpretação correta. O objetivo desta videoaula foi o de divulgar a técnica correta da realização do eletrocardiograma a fim de se obter um traçado com qualidade.

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Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica na Área de Especialização de Energia

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica