Thesis (Ph. D.) -- Virginia Commonwealth University, 2005. / Title from title-page of electronic thesis. Prepared for: Dept. of Anatomy and Neurobiology. Bibliography: leaves 75-83.

Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 133 pages. Includes Vita. Includes bibliographical references.

Theses (M.S.)--Marshall University, 2006. / Title from document title page. Includes abstract. Includes vitae. Document formatted into pages: contains viii, 143 p. Bibliography: p. 52-58.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Made available in DSpace on 2014-06-11T19:22:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-10Bitstream added on 2014-06-13T20:09:54Z : No. of bitstreams: 1 silva_cr_me_prud.pdf: 377360 bytes, checksum: 38ec03183b67a69d80d817be978919e6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / São encontradas na literatura várias propostas de processamento do sinal eletromiográfico (EMG) com o objetivo de determinar índices aplicados à monitoração do processo de fadiga muscular localizada. Em comum, todos os índices são baseados na análise de algum parâmetro do sinal monitorado durante o exercício. A avaliação conjunta do comportamento das variáveis extraídas no domínio do tempo e da frequência do sinal eletromiográfico (EMG) não é uma tarefa trivial. Diante disso, os objetivos do estudo foram: i) identificar por meio do comportamento da frequência mediana (Fmed) e da raiz quadrada da média (RMS) do sinal EMG o momento de instalação da fadiga muscular localizada (MF); ii) determinar a reprodutibilidade entre dias da Fmed, RMS, e bandas de baixa (20-45 Hz), média (46-95 Hz) e alta (96-400 Hz) frequência do sinal EMG e iii) aplicar uma análise estatística multivariada nas variáveis extraídas do sinal EMG durante o início, MF e final do teste. Dezoito sujeitos saudáveis foram avaliados em dois dias diferentes, sendo registrados os sinais EMG dos músculos vasto medial (VM), reto femoral (RF) e vasto lateral (VL) durante contrações isométricas a 20% e 70% da contração voluntária isométrica máxima (CVIM), realizada até a exaustão. Por meio das análises realizadas no comportamento da Fmed e do RMS ao longo dos testes foi possível identificar o MF para o VM e VL em ambas as intensidades de carga... / Various proposals are found in the literature of electromiographic signal (EMG) processing with the purpose of determining indices applied to monitoring the localized muscle fatigue. In common, all indexes are based on analysis of some signal parameter monitored during the exercise. The joint evaluation of the behavior of variables extracted in the time and frequency domain of the EMG signal is not a trivial task. That said, the objectives of the study were: i) identify through the behavior of median frequency (MFreq) and the root mean square (RMS) of EMG signal in the moment of installation of localized muscle fatigue (MF); ii) determining the reproducibility between days of MFreq, RMS, and low bands (20-45 Hz), average (46-95 Hz) and high (96-400 Hz) frequency of EMG signal and iii) applying a multivariate statistical analysis in variables extracted from EMG signal during the beginning, MF and end of test. Eighteen healthy subjects were evaluated in two different days, being recorded the EMG muscle signals of vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) during isometric contractions at 20% and 70% of maximum isometric voluntary contraction (MIVC), held until exhaustion. The analysis of MFreq and RMS behavior over the tests was possible to identify the MF for VM and VL in both load intensities. There were... (Complete abstract click electronic access below)

Orientador: Fábio Mícolis de Azevedo / Banca: Neri Alves / Banca: Fernando Henrique Magalhães / Resumo: São encontradas na literatura várias propostas de processamento do sinal eletromiográfico (EMG) com o objetivo de determinar índices aplicados à monitoração do processo de fadiga muscular localizada. Em comum, todos os índices são baseados na análise de algum parâmetro do sinal monitorado durante o exercício. A avaliação conjunta do comportamento das variáveis extraídas no domínio do tempo e da frequência do sinal eletromiográfico (EMG) não é uma tarefa trivial. Diante disso, os objetivos do estudo foram: i) identificar por meio do comportamento da frequência mediana (Fmed) e da raiz quadrada da média (RMS) do sinal EMG o momento de instalação da fadiga muscular localizada (MF); ii) determinar a reprodutibilidade entre dias da Fmed, RMS, e bandas de baixa (20-45 Hz), média (46-95 Hz) e alta (96-400 Hz) frequência do sinal EMG e iii) aplicar uma análise estatística multivariada nas variáveis extraídas do sinal EMG durante o início, MF e final do teste. Dezoito sujeitos saudáveis foram avaliados em dois dias diferentes, sendo registrados os sinais EMG dos músculos vasto medial (VM), reto femoral (RF) e vasto lateral (VL) durante contrações isométricas a 20% e 70% da contração voluntária isométrica máxima (CVIM), realizada até a exaustão. Por meio das análises realizadas no comportamento da Fmed e do RMS ao longo dos testes foi possível identificar o MF para o VM e VL em ambas as intensidades de carga... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Various proposals are found in the literature of electromiographic signal (EMG) processing with the purpose of determining indices applied to monitoring the localized muscle fatigue. In common, all indexes are based on analysis of some signal parameter monitored during the exercise. The joint evaluation of the behavior of variables extracted in the time and frequency domain of the EMG signal is not a trivial task. That said, the objectives of the study were: i) identify through the behavior of median frequency (MFreq) and the root mean square (RMS) of EMG signal in the moment of installation of localized muscle fatigue (MF); ii) determining the reproducibility between days of MFreq, RMS, and low bands (20-45 Hz), average (46-95 Hz) and high (96-400 Hz) frequency of EMG signal and iii) applying a multivariate statistical analysis in variables extracted from EMG signal during the beginning, MF and end of test. Eighteen healthy subjects were evaluated in two different days, being recorded the EMG muscle signals of vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) during isometric contractions at 20% and 70% of maximum isometric voluntary contraction (MIVC), held until exhaustion. The analysis of MFreq and RMS behavior over the tests was possible to identify the MF for VM and VL in both load intensities. There were... (Complete abstract click electronic access below) / Mestre

L'objectif général de ce travail doctoral était d'étudier la plasticité de la fonction posturale à travers l’étude des effets d’un programme d'entraînement unilatéral ou d’une expérience sportive et/ou motrice. Pour cela, les effets de différents types d'exercices chroniques (volontaire et électro-induit) et aigus (tâche posturale répétée, échauffement et fatigue) ont été testés sur le contrôle postural monopodal en condition statique et dynamique. Les principaux résultats montrent que le programme d'entraînement unilatéral constitué de contractions volontaires et de contractions électro-induites n'a pas amélioré le contrôle postural du membre ipsilatéral et du membre controlatéral en dépit de l'augmentation de la force musculaire pour les deux membres chez des jeunes adultes sains non actifs. L'absence de résultat relatif au contrôle postural pourrait, principalement, être liée aux modalités et conditions des programmes d'entraînement qui n’étaient pas suffisamment proches des conditions écologiques du contrôle postural. En revanche, l'exercice aigu non-fatiguant comme l'échauffement a amélioré le contrôle postural monopodal chez des jeunes étudiants sportifs quelle que soit la jambe sur laquelle ils étaient évalués. Cependant, cette amélioration n’apparait qu’au bout de 10-15 minutes selon la jambe considérée après l'arrêt de l'exercice. Par ailleurs, chez des athlètes pratiquant des sports symétriques et asymétriques, les exercices aigus non-fatiguant comme la répétition d’une tâche posturale et l'échauffement, ont engendré des effets bénéfiques sur le contrôle postural monopodal statique et ont permis de distinguer la jambe dominante de la jambe non-dominante. En revanche, l'exercice aigu fatiguant a perturbé le contrôle postural indépendamment de la nature du sport pratiqué et de la jambe évaluée. / The overall objective of this thesis was to study the plasticity of postural function by investigating the effects of a unilateral training program or a sport and/or motor experience. Hence, the effects of various types of chronic (voluntary and electro-induced) and acute exercises (repeated postural task, warm-up and fatigue) were tested on monopodal postural control in static and dynamic conditions. The main findings show that the unilateral training program of voluntary contractions and electro-induced contractions did not improve postural control of the ipsilateral and contralateral limbs despite the increase in muscle strength for both in healthy non-active young adults. The lack of postural control outcome may be primarily related to the conditions of training programs that were not sufficiently close to the ecological conditions of postural control. In contrast, non-fatiguing high-intensity exercise such as warm-up improved monopodal postural control in young sports students regardless of which leg they were assessed. However, this improvement does not appear until 10-15 minutes according to the considered leg after stopping the exercise. Moreover, in athletes practicing symmetrical and asymmetrical sports, the non-fatiguing, acute exercises such as the repetition of a postural task and the warm-up, generated beneficial effects on the static monopodal postural control and enabled to distinguish the dominant leg of the non-dominant leg. In contrast, the fatiguing acute exercise disrupted postural control regardless of the nature of sport practiced and the leg assessed.

abstract: Skeletal muscle injury may occur from repetitive short bursts of biomechanical strain that impair muscle function. Alternatively, variations of biomechanical strain such as those held for long-duration are used by clinicians to repair muscle and restore its function. Fibroblasts embedded within the unifying connective tissue of skeletal muscle experience these multiple and diverse mechanical stimuli and respond by secreting cytokines. Cytokines direct all stages of muscle regeneration including myoblasts differentiation, fusion to form myotubes, and myotube functionality. To examine how fibroblasts respond to variations in mechanical strain that may affect juxtapose muscle, a myofascial junction was bioengineered that examined the interaction between the two cell types. Fibroblasts were experimentally shown to increase myoblast differentiation, and fibroblast biomechanical strain mediated the extent to which differentiation occurred. Intereleukin-6 is a strain-regulated cytokine secreted by fibroblasts was determined to be necessary for fibroblast-mediated myoblast differentiation. Myotubes differentiated in the presence of strained fibroblasts express greater number of acetylcholine receptors, greater acetylcholine receptor sizes, and modified to be more or less sensitive to acetylcholine-induced contraction. This study provides direct evidence that strained and non-strained fibroblasts can serve as a vehicle to modify myoblast differentiation and myotube functionality. Further understanding the mechanisms regulating these processes may lead to clinical interventions that include strain-activated cellular therapies and bioengineered cell engraftment for mediating the regeneration and function of muscle in vivo. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2014

Orientador: Maria Claudia Gonçalves de Oliveira Fusaro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Aplicadas / Made available in DSpace on 2018-08-25T13:04:54Z (GMT). No. of bitstreams: 1 Santos_DiogoFranciscodaSilvados_M.pdf: 1159978 bytes, checksum: d14c7c199ca0e75686645ae3ca6a131c (MD5) Previous issue date: 2014 / Resumo: De todas as dores que acometem o ser humano ao longo da sua existência, a dor muscular, especialmente a induzida por contração isométrica sustentada, é uma das mais prevalentes e possui um importante impacto sócio-econômico. Entretanto, apesar da sua relevância clínica, os mecanismos moleculares envolvidos no desenvolvimento da dor muscular induzida pela contração isométrica sustentada são pouco conhecidos. Isto se deve, principalmente, à ausência de um modelo experimental mais realístico e com bom grau de predição do controle farmacológico desta dor. Portanto, o objetivo deste trabalho foi desenvolver um novo modelo de hiperalgesia muscular induzido por contração isométrica sustentada em ratos. A contração isométrica sustentada foi realizada por estimulações elétricas aplicadas diretamente no ventre do músculo gastrocnêmio de ratos wistar e os parâmetros foram de 19 milissegundos de duração de pulso, frequência em 50 Hertz, intensidade de 1,6 Volts (V) por um período de 1 hora. A hiperalgesia muscular mecânica foi avaliada com o método Randall Selitto nos tempos de meia hora até 48 horas após o término da contração isométrica sustentada. A contração isométrica sustentada, obedecendo o parâmetros supracitados, induziu hiperalgesia muscular mecânica por 1 hora, regredindo com valores próximos ao basal 2 horas após o término da contração. As respostas com 1,6V por 1 hora, foram significativamente maiores do que as induzidas por estimulações de 1,6V por 15 e 30 minutos; 0,5 e 1,0V por 1h ou sham. Demonstramos ainda que a hiperalgesia muscular mecânica induzida pela contração isométrica sustentada foi bloqueada pela dexametasona, evidenciando o caráter inflamatório desse novo modelo, respaldado pela presença de células inflamatórias no tecido muscular, confirmadas pela análise histológica. Juntos, estes dados sugerem que esse novo modelo de hiperalgesia muscular se aproxima de uma condição mais próxima da real encontrada nas dores musculares decorrentes das atividades diárias, além de possuir um grande potencial científico para os estudos dos mecanismos fisiopatológicos envolvidos na dor muscular relacionada à contração isométrica sustentada / Abstract: Among the types of pain that affect people throughout their lives, muscle pain, specially the one induced by sustained isometric contraction, is one of the most prevalent and has an important socio-economic impact. However, despite their clinical relevance, the molecular mechanisms involved in the development of muscle pain induced by sustained isometric contraction are unknown. This is mainly due to the absence of a more realistic experimental model that has a good degree of prediction of pharmacological control of pain. Therefore, the aim of this study was to develop a new model of muscle hyperalgesia induced by sustained isometric contraction in Wistar rats. The sustained isometric contraction was performed by the electrical stimulation directly to the belly of the gastrocnemius muscle of rats and the parameters were 19 millisecond of pulse duration, frequency of 50Hz, and intensity of 1.6 volts (V) for a period of 1 hour. Randall Selitto method was used to measure muscular hyperalgesia 30 minutes until 48 hours after the finish of sustained isometric contraction. This protocol induced mechanical muscle hyperalgesia for one hour and, after two hours, the responses were similar to the baseline. These responses were significantly higher than those induced by stimulation 1.6V for 15 and 30 minutes, 0.5 and 1.0 V for 1h or sham. We also demonstrated that the mechanical muscle hyperalgesia induced by sustained isometric contraction was blocked by dexamethasone, indicating the inflammatory nature of this new model, supported by the presence of inflammatory cells in muscle tissue, confirmed by histological analysis. Together, these data suggest that this new model of muscle hyperalgesia approaching a condition closest to the actual found in muscle pain resulting from daily activities, besides having a great scientific potential for the study of pathophysiological mechanisms involved in muscle pain related to contraction sustained isometric / Mestrado / Metabolismo e Biologia Molecular / Mestre em Ciências da Nutrição e do Esporte e Metabolismo

Fescue toxicosis is problematic for ruminant livestock, causing weight loss and low productivity when fed endophyte-infected forages. Complete underlying mechanisms of toxicosis are unknown therefore; the objective of the study was to determine if ruminally dosed ergot alkaloids impact rumen motility. Cannulated steers were pair-fed a forage diet and ruminally dosed with endophyte-free (E-) or endophyte-infected (E+) tall fescue seed. An 8-h period of rumen motility collection began 4-h after feeding by monitoring pressure change via a wireless telemetry and transducer system. In experiment 1, steers were paired by weight and assigned to E- or E+ treatment. Overall, E+ steers had more frequent contractions. On d 7 - 9, both treatments had lower frequencies and E- steers had greater amplitude of contractions, which corresponded with decreased DM intake. In experiment 2 steers remained in pair, but switched treatment. During the 57 d E+ steers received titrated levels of ergovaline + ergovalinine. There was no difference between treatments for frequency or amplitude of contractions, but increasing dosage, decreased frequency (d 1 - 44) and amplitude, coinciding with lower DM intakes. Alteration in rumen motility associated with changes in intake may be responsible for the decreased productivity in ruminants consuming E+ forages.