Myosin 1H and the soft tissue profile of african american females with mandibular prognathism

Introduction: The aim of this study was to explore the influence of Myosin 1H on the soft tissue profile of African American females. Methods: Fourteen African American females from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository with the ancestral genotype GG, marker rs10850110, locus 12q24.11 were analyzed. For this investigation, measurements were taken of the eleven items that comprise the Holdaway soft tissue analysis. Profile differences between ethnicity and corresponding normative values were explored by independent-sample t tests for all facial profile measurements. Student's t test for independent means was used to determine differences with accepted norms. Significance was set a p<0.05. Results: There were significant differences between four of the eleven Holdaway values and the reported values for African Americans. The mean convexity value of the African American female group was 1.0 mm less the normative value of 5.7 mm (p>0.000). In contrast, the H angle of the African American females was larger than the normative value. Conclusions: Our study confirms previous research that Myosin 1H contributes to mandibular prognathism. It agrees with the idea that Myosin 1H is less influential in the maxillary soft tissue complex. Understanding the genetic influence of soft tissue growth would allow improved therapies and prevention approaches.

Introduçâo: O objetivo desse estudo foi determinar a influência da miosina 1H nos tecidos moles de mulheres americanas negras. Métodos: Foram estudadas quatorze mulheres americanas negras participantes do projeto Dental Registry and DNA Repository da Faculdade de Odontologia da Universidade de Pittsburgh com o genótipo comum GG do marcador rs10850110, localizado no lócus 12q24.11. Medidas de onze parâmetros que compõem a análise de tecidos moles de Holdaway foram utilizadas. Diferenças entre etnicidade e medidas normais correspondentes, foram exploradas através do teste t de Student de amostras independentes para todas as medidas faciais. O teste t de Student para médias independentes foi usado para determinar diferenças em comparação à medidas normais. A significância foi estabelecida em p<0,05. Resultados: Houve uma diferença estatisticamente significante entre quatro das onze medidas de Holdaway. A convexidade média da mulher americana negra foi de 1,0 mm a menos que o valor normal de 5.7 mm (p>0.000). Em contraste, o ângulo H das mulheres americanas negras foi maior que o valor normal. Conclusões: O nosso estudo confirma resultados anteriores que a miosina 1H contribui para o prognatismo mandibular. Nossos resultados concordam com a ideia de que a miosina 1H tem menor influência nos tecidos moles da maxila. Entender a influência genética no crescimento dos tecidos moles irá possivelmente permitir melhorar as abordagens de tratamento e prevenção atuais.

Adequação da assistência pré-natal segundo as características maternas no Brasil / Adequacy of prenatal care according to maternal characteristics in Brazil

OBJETIVO: Verificar o grau de adequação da assistência pré-natal no Brasil e sua associação com características sociodemográficas das mulheres. MÉTODOS: Este estudo nacional de base hospitalar foi realizado com 23 894 mulheres em 2011 e 2012. Os dados foram obtidos a partir de entrevistas com a puérpera e dos cartões de pré-natal. Considerou-se assistência pré-natal adequada aquela iniciada até a 12 semana gestacional, com realização de no mínimo seis consultas (número de consultas corrigido para a idade gestacional no momento do parto), registro no cartão de pré-natal de pelo menos um resultado de cada um dos exames preconizados na rotina de pré-natal e recebimento de orientação para maternidade de referência. Realizou-se regressão logística multivariada para verificar a associação entre características maternas e o grau de adequação da assistência pré-natal. RESULTADOS: Início precoce da atenção pré-natal foi observado em 53,9% das gestantes, número adequado de consultas em 73,2%, registro de pelo menos um exame preconizado em 62,9%, orientação para maternidade de referência em 58,7% e assistência pré-natal global adequada em 21,6%. Menor adequação do pré-natal foi observada em mulheres mais jovens, de pele preta, multíparas, sem companheiro, sem trabalho remunerado, com menos anos de estudo, de classes econômicas mais baixas e residentes nas regiões Norte e Nordeste do país. Após ajuste para características maternas, não foram observadas diferenças entre serviços públicos e privados quanto ao grau de adequação do cuidado pré-natal. CONCLUSÕES: A assistência pré-natal no Brasil alcançou cobertura praticamente universal, mas persistem desigualdades regionais e sociais no acesso a um cuidado adequado. Estratégias para facilitar o ingresso precoce no pré-natal são essenciais.

OBJECTIVE: To verify the degree of adequacy of prenatal care in Brazil and to determine whether it is associated with sociodemographic characteristics of women. METHODS: This nationwide hospital-based study was performed with 23 894 women in 2011 and 2012. Data were obtained from interviews with puerperal women and from the prenatal card recording prenatal care appointments. Adequate prenatal care was defined as that started no later than the 12th gestational week, with performance of at least six consultations (with number of consultations adjusted for gestational age at delivery), record in the prenatal card of at least one result for each of the recommended routine prenatal tests, and guidance regarding the maternity hospital for delivery. Multivariate logistic regression was performed to verify the association between maternal characteristics and the adequacy of prenatal care. RESULTS: Early onset of prenatal care was observed in 53.9% of participants, adequate number of consultations in 73.2%, record of at least one of each recommended test in 62.9%, guidance regarding maternity hospital in 58.7%, and overall adequate prenatal care in 21.6%. Less adequate prenatal care was observed in women who were younger, black, multiparous, who did not have a partner, without paid employment, having fewer years of formal schooling, belonging to lower socioeconomic classes, and living in the North and Northeast of Brazil. After adjustment of maternal characteristics, no differences were observed between public or private health care services regarding adequacy of prenatal care. CONCLUSIONS: Even though the coverage of prenatal care is virtually universal in Brazil, regional and social differences in the access and adequacy of care still persist. The implementation of strategies to facilitate early access to prenatal care is essential.

Isolated Schwannoma of the Olfactory Groove: A Case Report

Introduction Schwannoma of the olfactory groove is an extremely rare tumor that can share a differential diagnosis with meningioma or neuroblastoma. Objectives The authors present a case of giant schwannoma involving the anterior cranial fossa and ethmoid sinuses. Case Report The patient presented with a 30-month history of left nasal obstruction, anosmia, and sporadic ipsilateral bleeding. Computed tomography of the paranasal sinuses revealed expansive lesion on the left nasal cavity extending to nasopharynx up to ethmoid and sphenoid sinuses bilaterally with intraorbital and parasellar extension to the skull base. Magnetic resonance imaging scan confirmed the expansive tumor without dural penetration. Biopsy revealed no evidence of malignancy and probable neural cell. Bifrontal craniotomy was performed combined with lateral rhinotomy (Weber-Ferguson approach), and the lesion was totally removed. The tumor measured 8.0 4.3 3.7 cm and microscopically appeared as a schwannoma composed of interwoven bundles of elongated cells (Antoni A regions)mixed with less cellular regions (Antoni B). Immunohistochemical study stained intensively for vimentin and S-100. Conclusion Schwannomas of the olfactory groove are extremely rare, and the findings of origin of this tumor is still uncertain but recent studies point most probably to the meningeal branches of trigeminal nerve or anterior ethmoidal nerves. .

Modulatory effects of taurine on jejunal contractility

Taurine (2-aminoethanesulfonic acid) is widely distributed in animal tissues and has diverse pharmacological effects. However, the role of taurine in modulating smooth muscle contractility is still controversial. We propose that taurine (5-80 mM) can exert bidirectional modulation on the contractility of isolated rat jejunal segments. Different low and high contractile states were induced in isolated jejunal segments of rats to observe the effects of taurine and the associated mechanisms. Taurine induced stimulatory effects on the contractility of isolated rat jejunal segments at 3 different low contractile states, and inhibitory effects at 3 different high contractile states. Bidirectional modulation was not observed in the presence of verapamil or tetrodotoxin, suggesting that taurine-induced bidirectional modulation is Ca2+ dependent and requires the presence of the enteric nervous system. The stimulatory effects of taurine on the contractility of isolated jejunal segments was blocked by atropine but not by diphenhydramine or by cimetidine, suggesting that muscarinic-linked activation was involved in the stimulatory effects when isolated jejunal segments were in a low contractile state. The inhibitory effects of taurine on the contractility of isolated jejunal segments were blocked by propranolol and L-NG-nitroarginine but not by phentolamine, suggesting that adrenergic β receptors and a nitric oxide relaxing mechanism were involved when isolated jejunal segments were in high contractile states. No bidirectional effects of taurine on myosin phosphorylation were observed. The contractile states of jejunal segments determine taurine-induced stimulatory or inhibitory effects, which are associated with muscarinic receptors and adrenergic β receptors, and a nitric oxide associated relaxing mechanism.

Standardization of metachromatic staining method of myofibrillar ATPase activity of myosin to skeletal striated muscle of mules and donkeys / Padronização do método de coloração metacromático da atividade da miosina ATPase miofibrilar para músculo estriado esquelético de muares e asininos

This study aims at standardizing the pre-incubation and incubation pH and temperature used in the metachromatic staining method of myofibrillar ATPase activity of myosin (mATPase) used for asses and mules. Twenty four donkeys and 10 mules, seven females and three males, were used in the study. From each animal, fragments from the Gluteus medius muscle were collected and percutaneous muscle biopsy was performed using a 6.0-mm Bergstrõm-type needle. In addition to the metachromatic staining method of mATPase, the technique of nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) was also performed to confirm the histochemical data. The histochemical result of mATPase for acidic pre-incubation (pH=4.50) and alkaline incubation (pH=10.50), at a temperature of 37ºC, yielded the best differentiation of fibers stained with toluidine blue. Muscle fibers were identified according to the following colors: type I (oxidative, light blue), type IIA (oxidative-glycolytic, intermediate blue) and type IIX (glycolytic, dark blue). There are no reports in the literature regarding the characterization and distribution of different types of muscle fibers used by donkeys and mules when performing traction work, cargo transportation, endurance sports (horseback riding) and marching competitions. Therefore, this study is the first report on the standardization of the mATPase technique for donkeys and mules...

O presente estudo objetivou padronizar o pH e a temperatura da pré-incubação e incubação do método de coloração metacromática de myofibrillar atividade ATPase da miosina (mATPase) utilizada para asininos e muares. Vinte e quatro jumentos e 10 muares, sete machos e três fêmeas, foram usados no estudo. De cada animal, fragmentos do músculo Gluteus medius foram coletados e biópsia muscular percutânea foi realizada por meio de uma agulha Bergstrõm tipo de 6,0 mm. Em adição ao método de coloração metacromática de mATPase, a técnica de nicotinamida adenina dinucleótido tetrazólio redutase (NADH-TR) foi também realizada para confirmar os dados histoquímicos. O resultado histoquímico da mATPase por pré-incubação ácida (pH=4,50) e incubação alcalina (pH=10,50), a uma temperatura de 37ºC, foi o que proporcionou a melhor diferenciação das fibras coradas com azul de toluidina. As fibras musculares foram identificadas de acordo com as seguintes cores: tipo I (oxidativa, azul claro), tipo IIA (oxidativo-glicolítico, azul intermediário) e tipo IIX (glycolytic, azul escuro). Na literatura, não foram encontradas publicações pertinentes à caracterização e distribuição dos diferentes tipos de fibras musculares utilizadas pelos asininos e muares nos trabalhos de tração, no transporte de cargas, em provas esportivas de resistência (cavalgadas) e concursos de marcha. Dessa forma, essa pesquisa é o primeiro relato sobre padronização da técnica de mATPase para muares e asininos...

Histoquímica enzimática en el diagnósticode miopatías: revisión sistemática / Enzymatic histochemical in the diagnosis of myopathies: a systematic review

Introducción: Las enfermedades del músculo esquelético en las que la lesión supera la capacidad deadaptación conducen a cambios patológicos propios de las miopatías. En Colombia el diagnóstico serealiza mediante tinción con hematoxilina-eosina; sin embargo, la información brindada sobre algunosde los cambios del tejido muscular es limitada, por lo que es necesario realizar algunas técnicas de histoquímicaenzimática según la alteración. Objetivo: Describir los criterios de tinción de diferentes técnicashistoquímicas en el diagnóstico de las miopatías. Materiales y métodos: Se realizó una revisiónsistemática mediante la búsqueda de artículos en inglés y español indexados en las bases de ISI Web ofScience, Ovid Medline, PubMed, ScienceDirect y EBSCO. Los descriptores MeSH utilizados fueron:«histochemistry¼, «skeletal muscle¼, «structural and congenital myopathies¼, «fiber type fast twitch¼,«fiber type slow twitch¼ y «NADH tetrazolium reductase¼. Se asociaron a la búsqueda los términos«clinical application¼ y «diagnosis¼. Se seleccionaron los artículos originales, reportes de casos y revisionespublicadas entre 1982 y 2014 que aplicaran las técnicas de histoquímica en el diagnóstico de unamiopatía o en la investigación biomédica. Resultados: Se seleccionaron 64 publicaciones (incluidosdos libros) que fueron representativos para la redacción de este manuscrito, el cual fue complementadocon imágenes de biopsias musculares procesadas en el Laboratorio de Histología de la Universidad delValle, Colombia...

Introduction: The injuries on skeletal muscle that go beyond their capacity to adaptation result incharacteristic pathological changes of the myopathies. In Colombia for their diagnosis is usually usedthe hematoxylin-eosin stain, however, the information about many changes in muscle tissue is limited.That is why it is necessary to carry out certain enzymatic histochemical staining according to eachmyopathy. Objective: To describe the different criteria to diagnose myopathies by histochemical techniques.Material and methods: A systematic review was conducted which focused on search of all articleswritten in English and Spanish indexed in ISI Web of Science database, Ovid Medline, PubMed,ScienceDirect, and EBSCO. The MeSH descriptors used for the search were «histochemistry¼, «skeletalmuscle¼, «structural and congenital myopathies¼, «fast twitch fiber type¼, «slow twitch fiber type¼,and «NADH tetrazolium reductase¼. The terms «clinical application¼ and «diagnosis¼ were associatedto the search. All original articles, case reports, and reviews published during 1982-2014, which imple-mented histochemical techniques to the diagnosis of myopathy or to biomedical research were included.Results: From systematic search, 64 publications (including two books) were representative for thedrafting of this manuscript. The article was supplemented with images from muscle biopsies processedby the Laboratory of Histology, Universidad del Valle, Colombia...

Acute exposure to lead increases myocardial contractility independent of hypertension development

We studied the effects of the acute administration of small doses of lead over time on hemodynamic parameters in anesthetized rats to determine if myocardial contractility changes are dependent or not on the development of hypertension. Male Wistar rats received 320 µg/kg lead acetate iv once, and their hemodynamic parameters were measured for 2 h. Cardiac contractility was evaluated in vitro using left ventricular papillary muscles as were Na+,K+-ATPase and myosin Ca2+-ATPase activities. Lead increased left- (control: 112 ± 3.7 vs lead: 129 ± 3.2 mmHg) and right-ventricular systolic pressures (control: 28 ± 1.2 vs lead: 34 ± 1.2 mmHg) significantly without modifying heart rate. Papillary muscles were exposed to 8 µM lead acetate and evaluated 60 min later. Isometric contractions increased (control: 0.546 ± 0.07 vs lead: 0.608 ± 0.06 g/mg) and time to peak tension decreased (control: 268 ± 13 vs lead: 227 ± 5.58 ms), but relaxation time was unchanged. Post-pause potentiation was similar between groups (n = 6 per group), suggesting no change in sarcoplasmic reticulum activity, evaluated indirectly by this protocol. After 1-h exposure to lead acetate, the papillary muscles became hyperactive in response to a β-adrenergic agonist (10 µM isoproterenol). In addition, post-rest contractions decreased, suggesting a reduction in sarcolemmal calcium influx. The heart samples treated with 8 µM lead acetate presented increased Na+,K+-ATPase (approximately 140%, P < 0.05 for control vs lead) and myosin ATPase (approximately 30%, P < 0.05 for control vs lead) activity. Our results indicated that acute exposure to low lead concentrations produces direct positive inotropic and lusitropic effects on myocardial contractility and increases the right and left ventricular systolic pressure, thus potentially contributing to the early development of hypertension.

Effect of nitrofen in the final stages of development of the diaphragm muscle in rats / Efeito do nitrofen na fase final do desenvolvimento da musculatura do diafragma em ratos

PURPOSE: To evaluate the expression of myosin in muscle fibers of the diaphragm in experimental congenital diaphragmatic hernia (CDH). METHODS: Fetuses of pregnant rats were divided into four groups: External Control (EC), composed of non-manipulated rats; Nitrofen, composed of pregnant rats that received 100 mg of nitrofen (2,4-dichloro-4'nitrodiphenyl ether) diluted in olive oil on gestational day (GD) 9.5, whose fetuses developed CDH (N+) or not (N-), and Olive Oil Placebo (OO), composed of pregnant rats that received the oil on the same GD. The fetuses were collected on GD 18.5, 19.5, 20.5 and 21.5 (term = 22 days). We obtained body weight (BW) and photographed the diaphragm area (DA), hernia area (HA) and subsequent calculated the HA/DA ratio in N+ group. Samples of Diaphragm muscle were processed for histological staining with H/E and immunohistochemistry (IHQ) for myosin.} RESULTS: The fetuses of N- and N+ groups had decreased BW and DA compared to EC and OO groups (p <0.001). HA was decreased on GD 18.5 compared to 21.5 (p <0.001) and the HA/DA ratio showed no difference. IHQ showed decreased expression of myosin in nitrofen groups. CONCLUSION: CDH induced by nitrofen model contributes to the understanding of muscularization in the formation of the diaphragm where the myosin expression is decreased.

OBJETIVO: Avaliar a expressão da miosina na muscularização do diafragma na hérnia diafragmática congênita (CDH) experimental. MÉTODOS: Fetos de ratas foram divididos em quatro grupos: Controle Externo (EC), composto de ratas não manipuladas; Nitrofen, composto de ratas que receberam 100 mg de nitrofen (2,4-dicloro-4'nitrodifenil éter) diluído no azeite no dia de gestação (GD) 9.5, cujos fetos desenvolveram CDH (N+) ou não (N-) e Placebo óleo de oliva (OO), composto de ratas que ingeriram apenas óleo no mesmo GD. Os fetos foram coletados com 18,5, 19,5, 20,5 e 21,5 GD (termo = 22 dias). Foi obtido o peso corporal (BW) e tiradas fotografias da área do diafragma (DA), da hérnia (HA) e calculada a relação HA/DA no grupo N+. Amostras de diafragmas foram processadas histologicamente para coloração com H/E e imunohistoquímica. RESULTADOS: Os fetos dos grupos N- e N+ tiveram BW e DA diminuídos em relação aos grupos EC e OO (p<0.001). Só houve diferença na HA entre os GD 18.5 e 21.5 (p<0.001) e a relação HA/DA não mostrou diferença entre os grupos. A imunohistoquímica mostrou menor expressão de miosina nos grupos que receberam nitrofen. CONCLUSÃO: O modelo de CDH induzida por nitrofen contribui para entender a muscularização na formação do diafragma onde a expressão da miosina está diminuída.

Nemaline myopathy: clinical, histochemical and immunohistochemical features / Miopatia nemalínica: achados clínicos, histoquímicos e imuno-histoquímicos

Nemaline myopathy (NM) is a congenital disease that leads to hypotonia and feeding difficulties in neonates. Some cases have a more benign course, with skeletal abnormalities later in life. We analyzed a series of eight patients with NM obtained from a retrospective analysis of 4300 muscle biopsies. Patients were classified as having the typical form in five cases, intermediate form in two cases and severe form in one case. Histochemical analysis showed mixed rods distribution in all cases and predominance of type I fibers in five cases. Immunohistochemical analysis showed abnormal nebulin expression in all patients (four heterogeneous and four absent), homogeneous desmin expression in four cases, strongly positive in three and absent in one, fast myosin expression in a mosaic pattern in six cases and absent in two cases. There was no specific relation between these protein expression patterns and the clinical forms of NM.

Miopatia nemalínica (NM) é uma doença congênita que leva a hipotonia e dificuldade de sugar em neonatos. Alguns casos possuem uma evolução benigna, com deformidades ósseas tardias. Nós analisamos uma série de oito pacientes com NM obtidos da análise retrospectiva de 4300 biópsias musculares. Os pacientes foram classificados como forma típica em cinco casos, forma intermediária em dois casos e forma severa em um caso. Análise histoquímica mostrou distribuição mista dos rods em todos os casos e predominância de fibras tipo I em cinco casos. Análise imuno-histoquímica mostrou expressão anormal da nebulina em todos os pacientes (quatro heterogênea e quatro ausente), expressão homogenea da desmina em quatro casos, fortemente positiva em tres e ausente em um, expressão da miosina (rápida) com padrão em mosaico em seis casos e ausente em dois casos. Não há relação específica entre a expressão destas proteínas e as formas clínicas da NM.

Uma revisão sobre a plasticidade do músculo esquelético: expressão de isoformas de cadeia pesada de miosina e corre / Review on the plasticity of skeletal muscle: expression of myosin heavy chain isoforms and functional correlation

Introdução: O músculo esquelético é um tecido dinâmico com a habilidade intrínseca de se adaptar aos estímulos ambientais como resultado de mudanças qualitativas e quantitativas na expressão gênica, sendo esta capacidade definida como plasticidade. Este tecido é composto por populações de fibras rápidas e lentas que diferem fenotipicamente por expressarem diferentes isoformas de cadeias pesadas de miosina (CPM). Miosinas constituem uma família de proteínas chamadas "motores moleculares" com atividade ATOásica conhecidas por seu importante papel no processo de contração muscular. Objetivo: Realizar um levantamento, por meio de dados expostos na literatura, da relação existente entre a expressão de diferentes CPM no processo de remodelamento por meio de levantamento de dados descritos na literatura, senso consultados os bancos de dados internacionais "Pubmed" e "Highwire Press" e os bancos de dados nacionais Scielo e Lilacs, no período de janeiro a abril de 2008. Resultados: A fibra muscular pode alterar suas características contráteis por meio de mudanças nas quantidades das CPM. A velocidade de encurtamento do músculo esquelético varia de acordo com a isoforma de CPM que possui, conferindo assim ao tecido muscular a capacidade de adaptação frente a estímulos fisiológicos e patológicos. Conclusão: A fibra muscular pode alterar suas propriedades contráteis por meio de mudanças nas quantidades de isoformas de CPM que a constitui.

Lead reduces tension development and the myosin ATPase activity of the rat right ventricular myocardium

Lead (Pb2+) poisoning causes hypertension, but little is known regarding its acute effects on cardiac contractility. To evaluate these effects, force was measured in right ventricular strips that were contracting isometrically in 45 male Wistar rats (250-300 g) before and after the addition of increasing concentrations of lead acetate (3, 7, 10, 30, 70, 100, and 300 µM) to the bath. Changes in rate of stimulation (0.1-1.5 Hz), relative potentiation after pauses of 15, 30, and 60 s, effect of Ca2+ concentration (0.62, 1.25, and 2.5 mM), and the effect of isoproterenol (20 ng/mL) were determined before and after the addition of 100 µM Pb2+. Effects on contractile proteins were evaluated after caffeine treatment using tetanic stimulation (10 Hz) and measuring the activity of the myosin ATPase. Pb2+ produced concentration-dependent force reduction, significant at concentrations greater than 30 µM. The force developed in response to increasing rates of stimulation became smaller at 0.5 and 0.8 Hz. Relative potentiation increased after 100 µM Pb2+ treatment. Extracellular Ca2+ increment and isoproterenol administration increased force development but after 100 µM Pb2+ treatment the force was significantly reduced suggesting an effect of the metal on the sarcolemmal Ca2+ influx. Concentration of 100 µM Pb2+ also reduced the peak and plateau force of tetanic contractions and reduced the activity of the myosin ATPase. Results showed that acute Pb2+ administration, although not affecting the sarcoplasmic reticulum activity, produces a concentration-dependent negative inotropic effect and reduces myosin ATPase activity. Results suggest that acute lead administration reduced myocardial contractility by reducing sarcolemmal calcium influx and the myosin ATPase activity. These results also suggest that lead exposure is hazardous and has toxicological consequences affecting cardiac muscle.

A fibra muscular e fatores que interferem no seu fenótipo / The muscle fiber and the factors that interfere with its phenotype

O grande interesse atual em tirar proveito das variações na performance humana, nos levam a busca do entendimento as adaptações fisiológicas, bioquímicas e morfológicas nos tecidos envolvidos. Os resultados obtidos através de modelos experimentais fornecem informações para melhor entender a função muscular, e com isso permitir planejar um treinamento adequado ao objetivo pretendido, tendo como base adaptações fisiológicas. A performance esportiva depende de um grande número de fatores, o tipo do músculo e os estímulos a que ele é submetido e são sem dúvida parâmetros importantes para o desempenho atlético. Para cada modalidade é ideal ter um grupo de fibras predominante adequado às características específicas da atividade. Dependendo do tipo de estímulo podemos obter um aumento de força, sendo esta adaptação uma das mais importantes para a manutenção da saúde ou a melhora do desempenho atlético.

Correlação entre a proporção de fibras rápidas do músculo bíceps braquial e o torque relativo da flexão do cotovelo em sujeitos com hipótese clínica de miopatia / Correlation between the proportion of fast fibers in the biceps brachii muscle and the relative torque during elbow flexion in subjects with clinical hypothesis of myopathy

A produção de força muscular pode estar comprometida em pacientes portadores de miopatias. Estas representam um grupo heterogêneo de doenças com distintas características clínicas e morfológicas. Supõe-se que achados de desempenho funcional estejam relacionados com o tipo predominante de fibra expresso no músculo em análise. OBJETIVO: Correlacionar a proporção das fibras tipo 2 (FT2) do músculo bíceps braquial de sujeitos com hipótese clínica de miopatia (HCM) com picos de torque isométrico e isocinético de flexão do cotovelo. MATERIAIS E MÉTODOS: Participaram deste estudo sete sujeitos com HCM: quatro do sexo feminino com média de idade de 37 anos (dp= 9), peso de 73kg (dp= 26) e altura de 155cm (dp= 6); e três do sexo masculino com média de idade de 39 anos (dp= 1), peso de 88kg (dp= 5) e altura de 172cm (dp= 4). Pela técnica histoquímica de mATPase, foi realizada análise de proporção das fibras musculares. Após um mês da realização das biópsias, os sujeitos realizaram teste de força isométrica e isocinética concêntrica de flexão e extensão do cotovelo em dinamômetro isocinético. Avaliou-se o pico de torque (PT) isométrico a 90ºs-Õ e 180ºs-Õ e calculou-se o torque relativo 90 (TR90) e 180 (TR180). Para análise estatística, utilizou-se correlação de Spearman (r). RESULTADOS: A proporção de FT2 se correlacionou positivamente com TR180 (r= 0,89, p= 0,01). Uma moderada correlação foi encontrada entre FT2 e TR90 (r= 0,75, p= 0,05). CONCLUSÕES: Os resultados sugerem que o comportamento contrátil das FT2 não foi modificado nestes sujeitos. O dinamômetro isocinético mostrou ser um instrumento que pode avaliar, de forma não invasiva, a predominância do tipo de fibra muscular.

Muscular strength production may be impaired in myopathic patients. Myopathies represent a heterogeneous group of diseases with distinct clinical and morphological characteristics. It has been hypothesized that functional performance findings may be related to the predominant fiber type expressed in the muscle analyzed. OBJECTIVE: To correlate the proportion of type 2 fibers in the biceps brachii muscles of subjects with a clinical hypothesis of myopathy with their peak isometric and isokinetic torque during elbow flexion. METHOD: Seven subjects with a clinical hypothesis of myopathy participated in this study: four females of mean age 37 years (sd = 9), weight 73kg (sd= 26) and height 155cm (sd= 6); and three males of mean age 39 years (sd= 1), weight 88kg (sd= 5) and height 172cm (sd= 4). The muscle fiber proportion was analyzed using the mATPase technique. One month after taking biopsies, the subjects performed concentric isometric and isokinetic strength tests for elbow flexion and extension using an isokinetic dynamometer. The isometric and isokinetic peak torques at 90ºs-Õ and 180ºs-Õ were evaluated and the relative 90º (RT90) and 180º (RT180) torques were calculated. Spearman's correlation (r) was used for statistical analyses. RESULTS: The proportion of type 2 fibers correlated positively with RT180 (r= 0.89, p= 0.01), and there was a moderate correlation with RT90 (r= 0.75, p= 0.05). CONCLUSIONS: The results suggest that the contractile behavior of type 2 fibers was not modified in these subjects. The isokinetic dynamometer was shown to be an instrument capable of noninvasively evaluating muscle fiber type predominance.

El mecanismo molecular de la regulación de la contracción muscular / The molecular mechanism for the regulation of muscle contraction

La estructura de los filamentos gruesos de músculo estriado en el estado relajado ha sido finalmente comprendida a nivel molecular. La estructura revela interacciones intra- e intermoleculares que mantienen las cabezas de miosina unidas formando hélices adosadas a la superficie del filamento grueso. La fosforilación de las cadenas ligeras reguladoras de la miosina induce el debilitamiento de estas interacciones permitiendo la activación de los filamentos gruesos, produciendo el desorden y la liberación de las cabezas de miosina, y permitiendo su interacción con los filamentos delgados. Estos resultados abren las puertas para la comprensión del mecanismo molecular de la regulación ligada a miosina de la contracción muscular, de relevancia ya que las mutaciones asociadas a la cardiomiopatía hipertrófica medioventricular están ubicadas cercanas al sitio de fosforilación en las cadenas ligeras reguladoras de miosina.

Organ of Corti culture for functional analysis of precursor, support and hair cells

Em mamíferos a perda das células ciliadas determina perda auditiva neurosensorial permanente, já que estas células encontram-se em diferenciação terminal e seus precursores não mais entram no ciclo celular...

Loss of hair cells in mammals causes permanent sensorineural hearing loss, as these cells are terminally-differentiated and their precursors do not reenter the cell cycle. The aims of this study were to establish primary cell cultures and subcultures of organ of Corti...

Sarcopenia of ageing: functional, structural and biochemical alterations

Aging is associated with a progressive decline of muscle mass, strength, and quality, a condition described as sarcopenia of aging. Despite the significance of skeletal muscle atrophy, the mechanisms responsible for the deterioration of muscle performance are only partially understood. The purpose of this review is to highlight cellular, molecular and biochemical changes that contribute to age-related muscle weakness.

O envelhecimento está associado ao declínio progressivo da massa, força, e qualidade muscular, uma condição descrita como sarcopenia do envelhecimento. Apesar da importante atrofia do músculo esquelético, os mecanismos responsáveis pela deterioração do desempenho muscular são somente parcialmente conhecidos. A proposta desta revisão é ressaltar as alterações celulares, moleculares e bioquímicas que contribuem para a fraqueza muscular associada ao envelhecimento.

Diversity and plasticity of vertebrate skeletal muscle: insights from hybrid fibres

It is now generally accepted that hybrid skeletal muscle fibres are not experimental artefacts, but complex molecular systems that expand the functional repertoire of the muscle to which they belong. The purpose of this review is to highlight the cognitive value of hybrid fibres by discussing several insights into skeletal muscle biology produced by studies using hybrid fibres and/or muscles containing hybrid fibres. There is strong evidence that hybrid fibres can be used as indicators of muscle remodeling and specialization. Also, there is increasing evidence that hybrid fibres are suitable for investigating issues related to (i) the coexpression of different myosin heavy chain (MHC) isoforms and their assembly in the sarcomeric structure, (ii) the operation of the muscle cell as a multinuclear system, (iii) the tightness of the relationship between MHC isoform expression and expression of other polymorphic muscle proteins, (iv) the tightness of the relationship between MHC isoform expression and various contractile parameters, and (v) the extent of the neural input into defining the molecular and functional phenotype of skeletal muscle cells. It is predicted that, when used together with imaginatively designed methods, the hybrid fibres will further our (still limited) understanding of the regulation of muscle gene expression in multinuclear cells and of the interactions of gene products within and across different intracellular signalling pathways.

Cardiomiopatia hipertrófica / Hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica é doença genética autossômica dominante em mais da metade dos casos. Foram descritas, até o momento, mais de 270 mutações em dez genes que codificam proteínas do sarcômero cardíaco. Para cada gene existem diversas mutações, cada qual com particularidades quanto a hipertrofia miocárdica, penetrância e prognóstico, principalmente em relação a morte súbita. Há evidência de que outro fatores genéticos têm papel na hipertrofia da cardiomiopatia hpertrófica, como o polimorfismo no gene da enzima conversora da angiotensina e em outros genes modificadores, ambos podendo influenciar o grau de hipertrofia e, eventualmente, a ocorrência de morte súbita. Neste artigo são descritas as mutações relatadas na literatura, assim como nossa experiência no Instituto do Coração, que é a primeira no Brasil nessa moléstia

Differential expression of adhesion moleculesshaping the T-cell subset prevalence during the early phase of autoimmune and Trypanosoma cruzi-elicited myocarditis

The participation of cell adhesion molecules (CAMs) in the establishment of autoimmune and infectious myocarditis is an important matter of investigation and may have therapeutic implication. Trypanosoma cruzi infection induces a CD8-mediated myocarditis in patients with severe cardiomyopathy and experimental animals. Previously, we have proposed that this predominance of CD8+ T-cells is, at least in part, consequence of the differential expression of CAMs on circulating CD8+ lymphocytes. In the present study we investigated the participation of CAMs in shaping the phenotypic nature of the autoimmune CD4-mediated myosin-induced and the CD8-mediated T. cruzi-elicited myocarditis. We provide evidence that the prevalence of a certain T-cell subset inside the inflamed heart reflects the differential profile of the adhesion molecules VLA-4, LFA-1, and ICAM-1 displayed on a large proportion of this particular T-cell population in peripheral blood during the early phase of inflammation. Further, the expression of VCAM-1, ligand for VLA-4, and ICAM-1, counter-receptor for LFA-1, was up-regulated on vascular endothelium and paralleled the entrance of inflammatory cells into the cardiac tissue. Thus, this up-regulated expression of receptors-counter-receptors that regulate T-cell transmigration through the vascular endothelium may have an important role in the pathogenesis of the early phase of both autoimmune and infectious myocarditis.

Efeitos da imunização com antígenos de superfície de Streptococcus mutans na auto-reatividade / Effeets of immunization with Streptococcus mutans' surface antigens in auto-reaetivity of BALB/c mice

Camundongos BALB/c foram imunizados com antígenos de superfície de Streptococcus mutans, cepa GS5. Observamos que a imunização elevou significativamente os níveis de IgGs anticoração e antimiosina livres e presentes em imunocomplexos. No Westem-blotting estes auto-anticorpos reagiram com miosina cardíaca e principalmente com uma banda de 35kDa do extrato cardíaco. A análise histológica dos corações demonstrou ausência de alterações significativas nas válvulas ou miocárdio. Também não foram encontrados anticorpos ligados ao tecido cardíaco. O tratamento com ciclofosfamida foi capaz de reduzir os níveis de auto-anticorpos. não alterando porém o aspecto histológico do coração. Os resultados deste trabalho mostraram que os antígenos de superfície da cepa GS5 de S. mutans não foram capazes de iniciar uma lesão cardíaca em camundongos BALB/c, embora elevassem consideravelmente o nível de anticorpos livres e presentes em imunocomplexos reativos com coração e miosina.