Thesis (Ph. D.)--Columbia University, 1938. / Cover title. Vita. Bibliography: p. 33-37.

Thesis (Ph. D.)--Columbia University, 1938. / Cover title. Vita. Bibliography: p. 33-37.

Made available in DSpace on 2013-08-07T19:04:19Z (GMT). No. of bitstreams: 1 000449053-Texto+Completo-0.pdf: 899279 bytes, checksum: 3e7a9e237041f1a7387612396632404c (MD5) Previous issue date: 2013 / Introduction: The prevalence of obesity in the population is signaling a change in the landscape of health in Brazil. One of the consequences of this pathology is the musculoskeletal pain - and its influence in people’s social, personal and professional life - which is a big challenge for the multidisciplinary treatment of obesity. The objective of this study was to evaluate musculoskeletal pain in labor activities in obese individuals. Methods: Non-controlled cross-sectional study. During 8 months all obese individuals in preoperative following in a Tertiary Care Centre of Reference for the treatment of obesity and metabolic syndrome were invited to participate. 95 people filled the Nordic Musculoskeletal Questionnaire (QNSO) after signing Term of Consent and met the inclusion criteria for the study. Results: The study showed that 66. 31% of the subjects experienced musculoskeletal pain at some region of the body in the last 12 months and 44. 21% did not work, in the same period, because of musculoskeletal pain. There was a statistical association between Body Mass Index and the three aspects evaluated by the Nordic Musculoskeletal Questionnaire. Conclusion: The musculoskeletal pain was often reported by obese individuals who participated in this study and in most cases prevented the execution of work activities of these people. It’s important to continue the studies about this subject to better serve the health of this population. / Introdução: A prevalência de obesidade na população está sinalizando a mudança no panorama da saúde no Brasil. Dentre as consequências que esta patologia traz para os indivíduos, está a dor osteomuscular - e sua influência nos âmbitos social, pessoal e profissional das pessoas - que é um grande desafio para a equipe multidisciplinar de tratamento da obesidade. O objetivo deste trabalho foi avaliar a dor osteomuscular nas atividades laborais de indivíduos obesos.Métodos: Estudo transversal não-controlado. Durante 8 meses todos os indivíduos obesos em acompanhamento de pré-operatório em um Centro de Atendimento Terciário de Referência para o tratamento de Obesidade e Síndrome Metabólica foram convidados a participar da pesquisa. 95 pessoas preencheram o Questionário Nórdico de Sintomas Osteomusculares (QNSO) após assinarem Termo de Consentimento Livre e Esclarecido e terem preenchido os critérios de inclusão para o estudo. Resultados: O estudo evidenciou que 66,31% dos indivíduos sentiram dor osteomuscular em alguma região do corpo nos últimos 12 meses e que 44,21% deixaram de exercer atividade laboral alguma vez, no mesmo período, em função de dor osteomuscular. Houve associação estatística entre IMC e os três aspectos avaliados pelo QNSO. Conclusão: A dor osteomuscular foi muito relatada pelos indivíduos obesos que participaram deste estudo e na maioria dos casos impediu a execução de atividades laborais destas pessoas. Percebe-se a necessidade de continuar os estudos que abordem esta temática para melhor atender e intervir na saúde desta população.

O principal objetivo deste estudo foi propor uma metodologia para calcular da força de contato patelofemoral in vivo durante uma atividade dinâmica. Para isso, um protocolo foi operacionalizado permitindo a determinação de parâmetros biomecânicos das articulações tibiofemoral e patelofemoral. Especificamente, os parâmetros determinados foram: centro de rotação tibiofemoral, centro de rotação patelofemoral, linha de ação do ligamento patelar, linha de ação do músculo quadríceps, distância perpendicular do ligamento patelar, distância perpendicular do músculo quadríceps, força do ligamento patelar e força do músculo quadríceps. Para a determinação dos parâmetros foram utilizadas imagens radiográficas dinâmicas, obtidas no plano sagital, de um indivíduo executando um exercício de extensão de joelho em cadeia cinética aberta, a uma velocidade de 45o/s, em seis situações distintas: sem carga externa e com caneleiras de 1 a 5kg (implementadas de 1kg em 1kg) aplicadas à tíbia. As imagens radiográficas foram captadas a uma freqüência de amostragem de 50 Hz, utilizando-se um videofluoroscópio de marca Axiom Siemens Iconos R100. As imagens obtidas foram reproduzidas e digitalizadas utilizando uma placa de captura da marca Silicon Graphics 320. Foram desenvolvidas rotinas computacionais utilizando o software MatlabÒ para a análise dos dados. A propagação do erro na determinação da força de contato patelofemoral foi calculada pelo método de Kleine & McClintock. O protocolo desenvolvido com base na videofluoroscopia permite determinar todos parâmetros biomecânicos necessários para o modelamento da articulação patelofemoral. Os resultados sugerem que, em comparação com a lei de Hooke, a utilização da dinâmica inversa como forma de determinação da força de contato patelofemoral é mais apropriada. Isso pode ser confirmado pelos menores níveis de erro apresentados pela dinâmica inversa. Com base no método de Kleine & McClintock, a linha de ação do músculo quadríceps parece ser um parâmetro crítico no cálculo da força de contato patelofemoral. / The primary goal of this study was to propose a method to calculate the patellofemoral contact force in vivo during a dynamic activity. In order to do that, a protocol was operacionalized allowing to determine the biomechanical parameters of the tibiofemoral and patellofemoral joints. Specifically, the parameters determinated were: tibiofemoral rotation center, patellofemoral rotation center, patellar ligament’s action line, quadriceps muscle’s action line, the patellar ligament moment arm, the quadriceps muscle moment arm, patellar ligament’s force and quadriceps muscle force. To determine such parameters were used dynamic radiographycal images, obtained in the sagital plane, from one individual executing an exercise of knee’s extension in open kinetic chain, in a speed of 45º/s, in six distinct situations: without external load and with weights of 1 to 5kg (implemented 1kg to 1kg) applied to the tibia. The radiographic images were captured in a sampling frequency of 50Hz, through a videofluoroscope from Axiom Siemens Iconos R100. The images obtained were reproduced and digitalized using a capture plate Slicon Graphics 320. Computer routines were developed with the software Matlab® to analyze the data. The error propagation on patelofemoral contact force determination was calculated by the method of Kleine & McClintock. The protocol developed based on the videofluoroscopy allow to determine all the biomechanical parameters needed to the modeling of the patelofemoral joint. The results suggest that, in comparison with Hooke’s law, the use of inverse dynamics as a way to determine the patellofemoral contact force is more appropriated. This can be confirmed by lower levels of error presented in the inverse dynamics. Based on the Kleine & McClintock’s method, the action line of the quadriceps muscle seems to be a critical parameter on the calculus of the patelofemoral’s contact force.

Duchenne Muscular Dystrophy (DMD) is a fatal X-linked disorder affecting 1 out of every 3500 male births. The underlying cause of DMD is mutations within the dystrophin gene resulting in loss of protein expression, which leads to myofiber instability and damage. The constant damage of skeletal muscle causes sustained immune infiltration, marked by increased levels of cytokines, such as TGF-beta. Interestingly, TGF-beta can decrease the myogenic potential of satellite cells, thus preventing muscle regeneration. Previously, our lab has shown that knockdown of the Ste20 Like Kinase, SLK, in normal mammary epithelial cells was sufficient to delay TGF-beta induced epithelial to mesenchymal transition. Therefore, we speculated that decreasing SLK levels would be sufficient to decrease the anti-myogenic effects of TGF-beta both in cultured myoblasts and in a mouse model of muscular dystrophy. In the first section of this study, we explored the effect of muscle specific deletion of SLK on muscle development and regeneration. Skeletal muscle specific deletion of SLK did not impair muscle development, but caused a myopathy in older mice. Additionally, muscle regeneration was delayed, but not inhibited by SLK deletion. These findings indicated that SLK has beneficial roles in skeletal muscle, but was not absolutely required for optimal muscle development and regeneration. In the second section, we investigated the potential for SLK knockdown to mitigate the anti-myogenic effects of TGF-beta in vitro. Decreasing levels of SLK restored myoblast differentiation in the presence of TGF-beta in a p38 dependent manner. In the final section, we determined that SLK levels are elevated in dystrophic muscle and that subsequent deletion of SLK in the mdx mouse enhances terminal differentiation of myoblasts without further exacerbating the pathology of the disease. Collectively, this work demonstrates that SLK inhibition can provide a protective effect against the anti-myogenic effects of TGF-beta via upregulation of p38 activity.

When a muscle contracts it produces vibrations. The origin of these vibrations is not known in detail. The purpose of this study was to determine the mechanism associated with muscle vibrations. Mechanisms which have been proposed in the literature were described as theories (cross-bridge cycling, vibrating string and unfused motor unit theories). Specific predictions were derived from each theory, and tested in three conceptually different studies. In the first study, the influence of recruitment strategies of motor units (MUs) on the vibromyographic (VMG) signal was studied in the in-situ cat soleus using electrical stimulation of the soleus nerve. VMG signals increased with increasing recruitment and decreased with increasing firing rates of MUs. Similar results were obtained for the human rectus femoris (RF) muscle using percutaneous electrical stimulation of the femoral nerve. The influence of MU activation on muscle vibrations was studied in RF by analyzing VMG signals at different percentages (0-100%) of the maximal voluntary contraction (MVC). In our second study, we tested the effects of changing the material properties of the in-situ cat soleus (through muscle length changes) on the VMG signal. The magnitude of the VMG signal was higher for intermediate muscle lengths compared to the longest and the shortest muscle lengths. The decreased magnitude of the VMG signal at the longest and at the shortest muscle lengths was associated with increased passive stiffness and with decreased force transients during unfused contractions, respectively. In the third study, the effect of fatigue on muscle vibrations was studied in human RF and vastus lateralis (VL) musc1es during isometric voluntary contractions at a leveI of 70% MVC. A decrease in the VMG signal magnitude was observed in RF (presumably due to derecruitment of MUs) and an increase in VL (probably related to the enhancement of physiological tremor, which may have occurred predorninantly in a mediolateral direction) with fatigue. The unfused MU theory, which is based on the idea that force transients produced by MUs during unfused tetanic contraction is the mechanism for muscle vibrations, was supported by the results obtained in the above three studies.

O principal objetivo deste estudo foi propor uma metodologia para calcular da força de contato patelofemoral in vivo durante uma atividade dinâmica. Para isso, um protocolo foi operacionalizado permitindo a determinação de parâmetros biomecânicos das articulações tibiofemoral e patelofemoral. Especificamente, os parâmetros determinados foram: centro de rotação tibiofemoral, centro de rotação patelofemoral, linha de ação do ligamento patelar, linha de ação do músculo quadríceps, distância perpendicular do ligamento patelar, distância perpendicular do músculo quadríceps, força do ligamento patelar e força do músculo quadríceps. Para a determinação dos parâmetros foram utilizadas imagens radiográficas dinâmicas, obtidas no plano sagital, de um indivíduo executando um exercício de extensão de joelho em cadeia cinética aberta, a uma velocidade de 45o/s, em seis situações distintas: sem carga externa e com caneleiras de 1 a 5kg (implementadas de 1kg em 1kg) aplicadas à tíbia. As imagens radiográficas foram captadas a uma freqüência de amostragem de 50 Hz, utilizando-se um videofluoroscópio de marca Axiom Siemens Iconos R100. As imagens obtidas foram reproduzidas e digitalizadas utilizando uma placa de captura da marca Silicon Graphics 320. Foram desenvolvidas rotinas computacionais utilizando o software MatlabÒ para a análise dos dados. A propagação do erro na determinação da força de contato patelofemoral foi calculada pelo método de Kleine & McClintock. O protocolo desenvolvido com base na videofluoroscopia permite determinar todos parâmetros biomecânicos necessários para o modelamento da articulação patelofemoral. Os resultados sugerem que, em comparação com a lei de Hooke, a utilização da dinâmica inversa como forma de determinação da força de contato patelofemoral é mais apropriada. Isso pode ser confirmado pelos menores níveis de erro apresentados pela dinâmica inversa. Com base no método de Kleine & McClintock, a linha de ação do músculo quadríceps parece ser um parâmetro crítico no cálculo da força de contato patelofemoral. / The primary goal of this study was to propose a method to calculate the patellofemoral contact force in vivo during a dynamic activity. In order to do that, a protocol was operacionalized allowing to determine the biomechanical parameters of the tibiofemoral and patellofemoral joints. Specifically, the parameters determinated were: tibiofemoral rotation center, patellofemoral rotation center, patellar ligament’s action line, quadriceps muscle’s action line, the patellar ligament moment arm, the quadriceps muscle moment arm, patellar ligament’s force and quadriceps muscle force. To determine such parameters were used dynamic radiographycal images, obtained in the sagital plane, from one individual executing an exercise of knee’s extension in open kinetic chain, in a speed of 45º/s, in six distinct situations: without external load and with weights of 1 to 5kg (implemented 1kg to 1kg) applied to the tibia. The radiographic images were captured in a sampling frequency of 50Hz, through a videofluoroscope from Axiom Siemens Iconos R100. The images obtained were reproduced and digitalized using a capture plate Slicon Graphics 320. Computer routines were developed with the software Matlab® to analyze the data. The error propagation on patelofemoral contact force determination was calculated by the method of Kleine & McClintock. The protocol developed based on the videofluoroscopy allow to determine all the biomechanical parameters needed to the modeling of the patelofemoral joint. The results suggest that, in comparison with Hooke’s law, the use of inverse dynamics as a way to determine the patellofemoral contact force is more appropriated. This can be confirmed by lower levels of error presented in the inverse dynamics. Based on the Kleine & McClintock’s method, the action line of the quadriceps muscle seems to be a critical parameter on the calculus of the patelofemoral’s contact force.

Submitted by denise santos (denise.santos@ufc.br) on 2012-05-08T13:07:20Z No. of bitstreams: 1 2008_dis_obdjunior.pdf: 1576870 bytes, checksum: 1887ae1164408ce992e1b43d4a8b24dc (MD5) / Approved for entry into archive by Eliene Nascimento(elienegvn@hotmail.com) on 2012-05-08T16:53:29Z (GMT) No. of bitstreams: 1 2008_dis_obdjunior.pdf: 1576870 bytes, checksum: 1887ae1164408ce992e1b43d4a8b24dc (MD5) / Made available in DSpace on 2012-05-08T16:53:29Z (GMT). No. of bitstreams: 1 2008_dis_obdjunior.pdf: 1576870 bytes, checksum: 1887ae1164408ce992e1b43d4a8b24dc (MD5) Previous issue date: 2008 / DEOCLECIANO JÚNIOR, Otacílio Benvindo. Avaliação da atividade relaxante de 17-NOR-SUBINCANADINA e, um alcalóide isolado de Aspidosperma ulei MARKGR. sobre a musculatura lisa cavernosa de coelhos. 2008. 113 f. Dissertação (Mestrado em Farmacologia) - Universidade Federal do Ceará. Faculdade de Medicina, Fortaleza, 2008. / Past studies have shown that the indole alkaloidal rich fraction (F(3-5)) from Aspidosperma ulei Markgr. root bark displays pro-erectile function in vivo and a relaxant effect on isolated rabbit corpus cavernosum in vitro. Also, a recent study demonstrated the in vivo pro-erectile like activity of 17-nor-subincanadina E (SEC), an alkaloid isolated from stem bark of this plant. This study aimed to assess further the effect of SEC on the smooth muscle tone (spontaneous or induced) in vitro, utilizing the strips of tracheal, intestinal, vascular and corpus cavernosal tissues of rabbits. An attempt was also made to study the possible mechanism of SEC on rabbit corpus cavernosum (RbCC). RbCC strips, were mounted in organ baths containing Krebs solution. After equilibration, the tissues were precontracted with phenylephrine (10 µM) or potassium (40mM). SEC (1-100 μg/ml) caused a concentration dependent relaxation in the isolated rabbit corpus cavernosum precontracted with phenylephrine and displayed comparatively greater relaxant effect on corpus cavernosum IC50 [7,174 (3,155-16,31) μg/ml], SEC produced concentration-dependent relaxations of the aortic rings in endothelium intact and denuded IC50[29,76 (90,32–115,6) μg/ml] and IC50[ 26,13 (75,83–119,9) μg/ml], respectively, trachea rings IC50[60,25 (0,330-109,8) μg/ml], and of spontaneous motility in segments of duodenum IC50[76,78 (33,09–178,2) μg/ml]. The relaxant effect of SEC (1-100 µg/ml) on phenylephrine contraction was unaffected in the presence of adrenergic blockers (phentolamine and guanethidine), muscarinic blocker (atropine), KATP channel blocker (glibenclamide), Ca2+-dependent K+ channel blockers (apamin and iberiotoxin), and in the presence of N-omega-nitro-L-arginine methyl ester (L-NAME 100 µM)). However, the SEC relaxation was significantly attenuated by ODQ (30 μ M) (79.1%±4.5%, p <0.05). Incubations of RbCC with SEC (10 and 30 µg/mL) caused significant increases of cGMP (21.5%±4.2%, p <0.05) and cAMP (331.95%±26.1%, p <0.05) levels. Preincubation with SEC (10 and 30 µM) also significantly enhanced the relaxation response to the exogenous NO-donor (GTN) and an activator of adenyl cyclase (forskolin). the relaxations evoked by electrical stimulation was significantly decreased by SEC (10 µg/mL) (65.0%±10.9%, p <0.05). The phasic component of the contraction induced by K+ 40 mM as well as the maximal contraction elicited by increasing external Ca2+ concentrations in depolarized corpora cavernosa was inhibited by SEC (15 µg/mL). Our results indicate that SEC can induce comparatively a greater relaxant effect on rabbit cavernosal tissue in vitro via a mechanism that involves an increase of cAMP and cGMP levels and a blocking effect on calcium flux. These data suggest that Aspidiosperma ulei Markgr. can be explored as an alternative for the treatment of erectile dysfunction. / Estudos anteriores demonstraram que uma fração rica (F(3-5)) em alcalóides indólicos extraída das cascas da raiz de Aspidosperma ulei Markgr. exibe função pró-eretil in vivo e relaxamento em corpos cavernosos de coelhos in vitro. Um estudo recente demonstrou que 17-nor-subincanadina E (SEC), um alcalóide extraído das cascas do caule da mesma planta, apresentou atividade pró-eretil in vivo. O presente trabalho teve por objetivo avaliar o efeito desse alcalóide sobre o tônus de diferentes tipos de musculatura lisa de coelhos e investigar o mecanismo de ação da substancia sobre o músculo liso cavernoso in vitro. Os tecidos foram montados em banhos de 5 ml contendo solução de Krebs-Henseleit (CO2 5% - O2 95%; 37ºC). A resposta relaxante máxima induzida por SEC (1 – 100 µg/ml) em segmentos de corpos cavernosos de coelhos contraídos com fenilefrina (PHE-10μM) foi de 100%, e apresentou um efeito relaxante preferencial para esse tecido, IC50[7, 174 (3,155 - 16,31) μg/ml]. SEC promoveu também relaxamento em anéis de aorta na presença e na ausência de endotélio, IC50[29,76 (90,32 – 115,6) μg/ml] e IC50[26,13 (75,83 – 119,9) μg/ml], respectivamente, anéis de traquéia IC50[60,25 (0,330 – 109,8) μg/ml] e em segmentos de duodeno IC50[76,78 (33,09 – 178,2) μg/ml]. O relaxamento induzido por SEC (1 – 100 µg/ml) não foi afetado por bloqueadores adrenérgicos (fentolamina e guanetidina), muscarínicos (atropina), ou bloqueadores dos canais de potássio dependentes de ATP (KATP)(glibenclamida) e ativados por cálcio (Kca) (apamina e iberiotoxina) e nem na presença de L-NAME; a adição de ODQ (30 µM) bloqueou o relaxamento induzido por SEC (79,1% ± 4,5%; p<0,05). Observou-se também um aumento dos níveis teciduais de AMPc (331,95% ± 26,1%; p<0,05) e GMPc (21,5% ± 4,2%; p<0,05). SEC (10 µg/ml e 30 µg/ml) potencializou o relaxamento induzido por gliceriltrinitrato (GTN) e forskolina (FK) e foi capaz de diminuir o relaxamento induzido pela estimulação por campo elétrico (ECE) (65,0% ± 10,9%; p< 0,05). SEC 15 μg/ml bloqueou a contração induzida por CaCl2 1 - 300 mM em corpos cavernosos de coelhos pré-contraídos com K+ (40 mM), 0 Ca++. Nossos resultados indicam que SEC manifesta atividade relaxante preferencial no músculo liso cavernoso a nível periférico e que esse efeito está aparentemente relacionado com um aumento dos níveis de AMPc e GMPc e um possível bloqueio do fluxo de cálcio. Estes dados sugerem que Aspidosperma ulei Markgf. pode ser explorada como uma alternativa para o tratamento da disfunção erétil.

Orientador : Prof. Dr. Luiz Cláudio Fernandes / Dissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Biológicas, Programa de Pós-Graduaçao em Educaçao Física. Defesa: Curitiba, 13/04/2010 / Bibliografia: fls. 84-98 / Área de concentraçao: Exercício e esporte / Resumo: O treinamento resistido e o suporte nutricional estimulam a hipertrofia muscular. Inversamente, o repouso no leito, imobilizacao do membro, microgravidade, lesao da medula espinhal, lesao periferica, lesao tendinea, entre outros estimulos, resultam em atrofia muscular. A atrofia muscular pode surgir de situacoes como: elevacao da proteolise, diminuicao da sintese proteica ou ambas. A suplementacao com ƒÀ-hidroxi-ƒÀ-metilbutirato (HMB), tem sido utilizada como medida anti-catabolica, em situacoes desde caquexia ate lesoes musculares induzidas pelo exercicio. Diante disto, este estudo objetivou verificar quais os efeitos da suplementacao com HMB sobre a atrofia muscular induzida pela imobilizacao da pata posterior esquerda em posicao de encurtamento de ratos Wistar, durante um periodo de sete dias. Foram realizadas as seguintes analises: massa corporal total; peso do soleo; area de secao transversa das fibras musculares do soleo; analise ultra-estrutural dos sarcomeros das fibras musculares do soleo; proteolise total pela liberacao de tirosina do musculo em meio de incubacao; peroxidacao lipidica; expressao proteica do NF-kB e producao basal de lactato no meio de incubacao. Os animais foram submetidos a imobilizacao da pata posterior esquerda em posicao de encurtamento durante sete dias, divididos em dois grupos (HMB e placebo . CaCO3), e, suplementados por gavagem com 76 mg.kg.-1d-1 de HMB ou CaCO3. Foi verificado ao setimo dia que a imobilizacao da pata posterior diminuiu a massa corporal total, o peso do soleo, area de seccao transversa das fibras musculares do soleo e causou lesoes nos sarcomeros das fibras musculares do soleo em comparacao aos dos musculos nao imobilizados. Contudo, a suplementacao com HMB nao foi capaz de alterar estes parametros envolvidos na atrofia muscular em comparacao ao placebo. Diferentemente do que se esperava, os musculos atrofiados nao elevaram a taxa de proteolise em comparacao a dos musculos contra-lateral controles. A expressao do NF-KB nao alterou nos musculos sujeitos a imobilizacao ou controles de ambos os grupos. A producao de lipoperoxidos, e a producao basal de lactato do soleo em meio de incubacao elevaram-se nos musculos atrofiados em comparacao a dos contra-lateral, porem, a suplementacao com HMB nao alterou estes parametros. Diante destes resultados, conclui-se que a suplementacao com HMB nao foi capaz de alterar a atrofia muscular induzida pela imobilizacao, nem os parametros envolvidos na atrofia muscular induzida pela imobilizacao. A falta de elevacao na proteolise total dos musculos imobilizados em comparacao aos controles, e uma indicativa de que os musculos imobilizados estao se atrofiando devido a uma diminuicao da sintese proteica ao inves de um aumento na proteolise no setimo dia. / Abstract: Resistance training and nutritional support have been used to stimulate muscle hypertrophy. Conversely, bed rest, limb immobilization, microgravity, spinal cord injury, peripheral injury, tendon injury, and other stimuli result in muscle atrophy. Muscle atrophy can arise from situations such as: increased proteolysis, decreased protein synthesis, or both. Supplementation with â-hydroxy-â-methylbutyrate (HMB) has been used as anti-catabolic agent in situations leading to cachexia and also to muscle damage induced by exercise. This study aimed to assess the effects of HMB supplementation on muscle atrophy induced by immobilization of the hindlimb in a shortened position of rats over a period of seven days. We measured the followed: total body mass, soleus muscle weight, cross-sectional area of soleus muscle fibers, ultra-structural analysis of the sarcomeres of muscle fibers of the soleus, overall proteolysis by the release of tyrosine from muscle incubation, peroxidation lipid, protein expression of NF-kB and, basal production of lactate by the muscle. The animals were subjected to immobilization of the left hindlimb in a shortened position for seven days, and divided into two groups (HMB and placebo – CaCO3), and supplemented by gavage with 76 mg.kg.-1d-1 of HMB or CaCO3. We found that immobilization of the hindlimb reduced the total body mass, tweight of the soleus, cross-sectional area of muscle fibers of the soleus and caused damage to the sarcomeres of muscle fibers in soleus muscles when compared to non-immobilized. Supplementation with HMB was not able to change these parameters. Unlike what was expected, muscles atrophy did not increase the rate of proteolysis when compared to the contralateral muscles which were the control ones. The expression of NF-KB was not altered in muscle from immobilized or controls of both groups. The production of lipidperoxide and basal production of lactate in the soleus incubated increased in the muscles atrophied when compared to the contralateral side. Again, HMB supplementation did not alter these parameters. In summary supplementation with HMB was not able to reversal the skeletal muscle atrophy induced by immobilization, or the parameters involved in muscle atrophy induced by immobilization. The lack of increase in total proteolysis of the immobilized muscles compared to controls, is indicative of the immobilized muscle are atrophying due to a decrease in protein synthesis rather than an increase in proteolysis in the seventh day.

When a muscle contracts it produces vibrations. The origin of these vibrations is not known in detail. The purpose of this study was to determine the mechanism associated with muscle vibrations. Mechanisms which have been proposed in the literature were described as theories (cross-bridge cycling, vibrating string and unfused motor unit theories). Specific predictions were derived from each theory, and tested in three conceptually different studies. In the first study, the influence of recruitment strategies of motor units (MUs) on the vibromyographic (VMG) signal was studied in the in-situ cat soleus using electrical stimulation of the soleus nerve. VMG signals increased with increasing recruitment and decreased with increasing firing rates of MUs. Similar results were obtained for the human rectus femoris (RF) muscle using percutaneous electrical stimulation of the femoral nerve. The influence of MU activation on muscle vibrations was studied in RF by analyzing VMG signals at different percentages (0-100%) of the maximal voluntary contraction (MVC). In our second study, we tested the effects of changing the material properties of the in-situ cat soleus (through muscle length changes) on the VMG signal. The magnitude of the VMG signal was higher for intermediate muscle lengths compared to the longest and the shortest muscle lengths. The decreased magnitude of the VMG signal at the longest and at the shortest muscle lengths was associated with increased passive stiffness and with decreased force transients during unfused contractions, respectively. In the third study, the effect of fatigue on muscle vibrations was studied in human RF and vastus lateralis (VL) musc1es during isometric voluntary contractions at a leveI of 70% MVC. A decrease in the VMG signal magnitude was observed in RF (presumably due to derecruitment of MUs) and an increase in VL (probably related to the enhancement of physiological tremor, which may have occurred predorninantly in a mediolateral direction) with fatigue. The unfused MU theory, which is based on the idea that force transients produced by MUs during unfused tetanic contraction is the mechanism for muscle vibrations, was supported by the results obtained in the above three studies.