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.

Brazil: an emerging military power? The problem of the use of force in Brazilian international relations in the 21st century

The central goal of this paper is thinking about the Brazilian military power and its linking to the international ambitions of the country in the 21st century. After a comparative analysis to other BRICs and with a historical one about Brazil's strategic irrelevance, we aim to establish what the minimum military capacity Brazil would need in order to meet the country's latest international interests. Similarly, it will be discussed if the National Strategy of Defense, approved in 2008, and the recent strategic agreements signed with France represent one more step toward this minimum military capacity.

Piezoresistive sensors for force mapping of hip-prostheses

The success of artificial prosthetic replacements depends on the fixation of the artificial prosthetic component after being implanted in the thighbone. The materials for fixation are subject to mechanical stresses, which originate permanent deformations, incipient cracks and even fatigue fractures. This work shows the possibility of monitoring the mechanical stress over time in prosthesis. In this way, highly sensitive silicon thin-film piezoresistive sensors were developed attached to prosthesis and their results compared with commercial strain gauge sensors. Mechanical stress-strain experiments were performed in compressive mode, during 10,000 cycles. Experimental data was acquired at mechanical vibration frequencies of 0.5 Hz, 1 Hz and 5 Hz, and sent to a computer by means of a wireless link. The results show that there is a decrease in sensitivity of the thin-film silicon piezoresistive sensors when they are attached to the prosthesis, but this decrease does not compromise its monitoring performance. The sensitivity, compared to that of commercial strain gauges, is much larger due to their higher gauge factors (-23.5), when compared to the GFs of commercial sensors (2).

Angular and linear accelerations of a rolling cylinder acted by an external force

The dynamics of a cylinder rolling on a horizontal plane acted on by an external force applied at an arbitrary angle is studied with emphasis on the directions of the acceleration of the centre-of-mass and the angular acceleration of the body. If rolling occurs without slipping, there is a relationship between the directions of these accelerations. If the linear acceleration points to the right, then the angular acceleration is clockwise. On the other hand, if it points to the left, then the angular acceleration is counterclockwise. In contrast, if rolling and slipping occurs, the direction of the linear acceleration does not determine the direction of the angular acceleration. For example, the linear acceleration may point to the right and the angular acceleration clockwise or counterclockwise depending on the external force orientation and point of application.

Avaliação isocinética da força muscular dos isquiotibiais e quadricípite em atletas da equipa nacional portuguesa de taekwondo

Objectivos: Avaliar a força muscular bilateralmente ao nível dos músculos quadricípite e isquiotibiais em atletas da equipa nacional Portuguesa de Taekwondo. Amostra: Foi constituída por 6 dos 10 elementos que constituem a população de Taekwondistas do sexo masculino inscritos na Federação Portuguesa de Taekwondo, com presença regular nas selecções nacionais todos com um mínimo de 6 anos de prática. Os atletas apresentaram uma idade média 17,5 (+ 1,9) anos, com uma altura de 181,2 (+ 2,8) cm e com uma massa corporal total de 74,1 (+ 11,6) kg Metodologia: Procedeu-se à avaliação da força muscular dos participantes ao nível da musculatura flexora e extensora do joelho, no dinamómetro Biodex System 4, a uma velocidade de execução de 60º/s (4 repetições) e de 180º/s (10 repetições) com 60 segundos de intervalo, numa amplitude de movimento compreendida entre os 90 e os 0 graus. Todos os dados foram tratados no programa SPSS, versão 18.0, com um nível de significância de 0,05. Resultados: Verificou-se a existência de diferenças estatísticas significativas na análise do Peak Torque (p=0,023) aos 180º/seg para os flexores do joelho e do Peak Torque 30º (p=0,023) aos 180º/seg na acção dos extensores e flexores (p=0,037) do joelho, entre o membro dominante e não dominante. Constatou-se ainda a existência de um rácio Isquiotibiais/Quadricípite (55%) dentro dos valores normais do equilíbrio muscular do joelho. Discussão/Conclusão: Concluiu-se que foram encontradas diferenças nos níveis de força obtidos entre o membro dominante e não dominante, no entanto não foram encontrados desequilíbrios musculares clinicamente significativos. Assim como na relação Isquiotibiais/Quadricípite do próprio membro, não apontando por isso risco de lesão articular do joelho.

Force and pressure analysis during occasional loaded gait

O documento em anexo encontra-se na versão pre-print (versão inicial enviada para o editor).

Analysis of ground reaction force and electromyographic activity of the gastrocnemius muscle during double support

O documento em anexo encontra-se na versão post-print (versão corrigida pelo editor).

O uso do smartphone na avaliação do risco de queda associado ao envelhecimento

Introdução: O declínio do equilíbrio, da força dos membros inferiores e o medo de cair são fatores de risco de queda associados ao envelhecimento e a sua avaliação pode ser realizada pelo teste One Leg Standing (OLS), Sit to Stand (STS) e pela Falls Eficacy Scale (FES), respetivamente. As aplicações para smartphone constituem uma alternativa para a avaliação dos fatores de risco de queda no envelhecimento. Objetivo: Analisar a capacidade de uma aplicação para smartphone na avaliação dos testes STS, OLS e FES. Metodologia: Realizou-se um estudo analítico numa amostra de 27 voluntários com idade ≥ 60 anos. Realizaram-se os testes STS, OLS e a FES (versão iconográfica, apresentada no smartphone). Os dados foram recolhidos simultaneamente por um smartphone e pelo Qualisys Motion Capture Systems associado a uma plataforma de forças. Foi utilizado o r de Pearson ou Spearman para analisar as possíveis correlações. Resultados: No STS obteve-se uma correlação muito forte (rp=0.97) no número de repetições de ciclos Sit Stand Sit (SLS) e forte na duração média do SLS (rp=0.85) e das subfases Sit to Stand (rp=0.69) e Stand to Sit (rp=0.778), com p<0.001. As medidas de inclinação do tronco apresentaram correlações fortes, com exceção do ângulo inicial (p≥0.05). No OLS, verificou-se uma correlação moderada entre o deslocamento do centro de pressão peak to peak médio-lateral (rs=0.45; p=0.017) e antero-posterior (rs=0.39; p=0.046), root mean square médio-lateral (rs=0.39; p=0.046) e antero-posterior (rs=0.46; p=0.017) e área do estatocinesiograma (rs=0.45; p=0.018). Na FES obteve-se uma correlação moderada em três categorias: ‘tomar banho/duche’ (rs=0.49; p=0.010), ‘deitar/levantar da cama (rs=0.43; p=0.024) e ‘chegar aos armários’ (rs=0.38; p=0.050). Conclusão: A aplicação para smartphone parece avaliar corretamente os ciclos e a variação da inclinação do tronco no STS, porém parece necessitar de ser reajustada na FES e na velocidade do deslocamento do centro de pressão, no OLS.

Task-force para revitalização dos sistemas de informação

Este trabalho descreve as actividades desenvolvidas no âmbito de uma task-force para revitalizar a função Sistemas de Informação de uma grande empresa nacional. Apresenta, em particular, o sistema de indicadores de gestão definido nesse contexto

Avaliação do débito máximo da tosse (peak cough flow) na doença pulmonar obstrutiva crónica

Resumo Objectivos: Avaliação da Tosse em doentes com Doença Pulmonar Obstrutiva Crónica (DPOC). Identificar e determinar a relação dos factores preditivos que contribuem para a deterioração da capacidade de tosse nestes indivíduos. Tipo de estudo: Estudo observacional descritivo de natureza transversal. Definição dos casos: Os critérios de diagnóstico da DPOC são o quadro clínico e o Gold standard para diagnóstico da DPOC – a espirometria. População-alvo: Todos os utentes com patologia primária de DPOC diagnosticada que se desloquem ao serviço de função respiratória do Hospital de Viseu, para realizar provas. Método de Amostragem: Foi utilizada uma amostra aleatória constituída por todos os indivíduos, que cumpriram os critérios de inclusão, conscientes e colaborantes, que aceitaram participar neste estudo. Dimensão da amostra: Uma amostra de 55 indivíduos que se deslocaram ao serviço de função respiratória, entre Janeiro e Junho de 2009, para realizar provas de função respiratória. Condução do estudo: Os utentes que aceitaram participar neste estudo foram sujeitos a um questionário de dados clínicos e realizaram 5 testes: índice de massa corporal (IMC), estudo funcional respiratório e gasometria arterial, avaliação da força dos músculos respiratórios (PImax e PEmax) e avaliação do débito máximo da tosse (Peak Cough Flow). Análise estatística: Foram obtidos dados caracterizadores da amostra em estudo, sendo posteriormente correlacionado o valor de débito máximo da tosse (Peak Cough Flow) com os resultados obtidos para as avaliações do IMC, estudo funcional respiratório, PImax e PEmax, gasometria, avaliação da capacidade de Tosse e número de internamentos no último ano por agudização da DPOC. Tendo sido encontrados os valores de correlação entre o Peak Cough Flow e os restantes parâmetros. Resultados: Após análise dos resultados, foram obtidos os valores de Peak Cough Flow para a população com DPOC e verificou-se valores diminuídos em comparação com os valores normais da população, tendo-se verificado maiores valores de PCF em indivíduos do sexo masculino, em comparação aos valores do sexo feminino. Foi analisada a relação entre o PCF e a idade, peso, altura e IMC, não tendo sido encontrada relação, dado que a tosse não apresenta uma variação segundo os valores antropométricos, tal como a relação com os valores espirométricos. Quanto aos parâmetros funcionais respiratórios foram analisadas as relações com o PCF. Verificou-se relações significativas entre o PCF e o FEV1, a FVC, o PEF, apresentando uma relação positiva, onde maiores valores destes parâmetros estão correlacionados com maiores picos de tosse. Quanto a RAW e RV, o PCF apresenta uma relação negativa, onde uma maior resistência da via aérea ou doentes mais hiperinsuflados leva a menores valores de PCF. Por outro lado não foi encontrada relação entre o PCF e a FRC e o TLC. Quanto à força dos músculos respiratórios, verificou-se relação significativa com o PImax e a PEmax em que a fraqueza ao nível dos músculos respiratórios contribuem para um menor valor de PCF. Relativamente aos valores da gasometria arterial, verificou-se relação entre o PCF e a PaO2 de forma positiva, em que doentes hipoxémicos apresentam menores valores de tosse, e a PaCO2, de forma negativa, em que os doentes hipercápnicos apresentam menores valores de PCF tendo sido verificada relação entre o PCF e o pH e sO2. Quanto à relação entre o número de internamentos por agudização da DPOC no último ano e o PCF verificou-se uma relação significativa, onde um menor valor de PCF contribui para uma maior taxa de internamento por agudização da DPOC. Conclusão: Este conjunto de conclusões corrobora a hipótese inicialmente formulada, de que o Peak Cough Flow se encontra diminuído nos indivíduos com Doença Pulmonar Obstrutiva Crónica onde a variação do PCF se encontra directamente relacionada com os parâmetros funcionais respiratórios, com a força dos músculos respiratórios e com os valores de gasometria arterial. ABSTRACT: Aims: Cough evaluation in Chronic Obstructive Pulmonary Disease (COPD) patients. Identify and determine the relation of the predictive factors that contribute to the cough capacity degradation in this type of patients. Type of study: Descriptive observational study of transversal nature. Case definition: The COPD diagnosis criteria are the clinical presentation and the gold standard to the COPD diagnosis- the Spirometry. Target Population: Every patients, with primary pathology of COPD diagnosed, who went to the respiratory function service of Viseu hospital to perform tests. Sampling Method: It was used a random sample constituted by all the, conscious and cooperating individuals, who complied with the inclusion criteria and who accepted to make part of this study. Sample size: A sample of 55 individuals that went to the respiratory function service between January and June 2009 to perform respiratory function tests. Study: The patients who accepted to make part of this study were submitted to a clinical data questionary and performed 5 tests: body mass index (BMI), respiratory functional study, arterial blood gas level, evaluation of respiratory muscles strength (maximal inspiratory pressure (MIP) and maximum expiratory pressure (MEP)), and Peak Cough Flow evaluation. Statistic Analysis: Were obtained characterizing data of the sample in study, and later correlated the value of the Peak Cough Flow with the results from the evaluation of the body mass index (BMI), the respiratory functional study the MIP and MEP, the arterial blood gas level and also with the ability to cough evaluation and the number of hospitalizations in the last year for COPD exacerbations. The values of correlation between the Peak Cough Flow and the other parameters were found. Results: After analyzing the results, were obtained the values of Peak Cough Flow for the population with COPD. There were decreased values compared with the population normal values, having been found higher values of PCF in males compared to female values. It was analyzed the relation between the PCF and the age, weight, height and BMI but no relation was found on account of the fact that the cough does not show a variation according to anthropometric parameters, such as the relation with spirometric values. As for the respiratory functional parameters were analyzed relations with the PCF. There were significant relations between the PCF and FEV1, the FVC, the PEF, presenting a positive relation, where higher values of these parameters are correlated with higher incidence of cough. Concerning the RAW and RV, the PCF has a negative relation, in which a higher airway resistance or in more hyperinflated patients, leads to lower values of PCF. On the other hand no correlation was found between the PCF and the FRC and TLC. Regarding the respiratory muscle strength, there was a significant relation with the MIP and MEP, in which the weakness at the level of respiratory muscles contribute to a lower value of PCF. For values of arterial blood gas level, there was no relation between the PCF and PaO2, in a positive way, in which patients with hypoxemia present lower values of cough, and PaCO2, in a negative way in which hypercapnic patients had lower values of PCF, having being founded a relation between the PCF and the pH and sO2. As for the relation between the number of hospitalizations for COPD exacerbation in the last year and the PCF was found a significant relation, in which a smaller value of PCF contributes to a higher rate of hospitalization for COPD exacerbation. Conclusion: This set of findings supports the hypothesis first formulated that Peak Cough Flow is decreased in individuals with Chronic Obstructive Pulmonary Disease, in which the variation of the PCF is directly related to the respiratory function parameters, the strength of respiratory muscles and the values of arterial blood gases.

Maximum level and time to peak of dam-break waves on mobile horizontal bed

Journal of Hydraulic Engineering, Vol. 135, No. 11, November 1, 2009

The friction force mouse-pad and the forearm muscles efforts (preliminary results)

The objective of the article is to evaluate the impact of the friction force mouse-pad in the contraction level of the forearm muscles M. extensor carpi ulnaris, M. extensor digitorum and M. extensor carpi radialis longus. A standard protocol of mouse movements was performed involving horizontal, vertical and diagonal mouse displacements drag-and-drop type. The operators were instructed to execute the protocol with their normal working speed. The movements protocol were performed by each subject (n=17) with three selected pairs mouse-pad, classified as low, medium and high friction force pairs. The mean time to execute the protocol with each mouse was ~138s. Mean values of ~13%MVE and ~17%MVE were found in the M. extensor carpi ulnaris and in the M. extensor digitorum respectively when performing the movements’ protocol. A 8.1% increase in %MVE was observed in the M. extensor digitorum and a 9.4% increase in %MVE was observed in the M. extensor carpi ulnaris when the high friction force pair was operated, relatively to the low friction force pair (p<0.05). The main preliminary conclusions of this study is that operating a high friction force mouse-pad may increase the risk to symptoms or disorders in the wrist due to an increase in the forearm muscles contraction levels, particularly during work with drawing application

Prognostic Value of a New Cardiopulmonary Exercise Testing Parameter in Chronic Heart Failure: Oxygen Uptake Efficiency at Peak Exercise - Comparison with Oxygen Uptake Efficiency Slope

INTRODUCTION: A growing body of evidence shows the prognostic value of oxygen uptake efficiency slope (OUES), a cardiopulmonary exercise test (CPET) parameter derived from the logarithmic relationship between O(2) consumption (VO(2)) and minute ventilation (VE) in patients with chronic heart failure (CHF). OBJECTIVE: To evaluate the prognostic value of a new CPET parameter - peak oxygen uptake efficiency (POUE) - and to compare it with OUES in patients with CHF. METHODS: We prospectively studied 206 consecutive patients with stable CHF due to dilated cardiomyopathy - 153 male, aged 53.3±13.0 years, 35.4% of ischemic etiology, left ventricular ejection fraction 27.7±8.0%, 81.1% in sinus rhythm, 97.1% receiving ACE-Is or ARBs, 78.2% beta-blockers and 60.2% spironolactone - who performed a first maximal symptom-limited treadmill CPET, using the modified Bruce protocol. In 33% of patients an cardioverter-defibrillator (ICD) or cardiac resynchronization therapy device (CRT-D) was implanted during follow-up. Peak VO(2), percentage of predicted peak VO(2), VE/VCO(2) slope, OUES and POUE were analyzed. OUES was calculated using the formula VO(2) (l/min) = OUES (log(10)VE) + b. POUE was calculated as pVO(2) (l/min) / log(10)peakVE (l/min). Correlation coefficients between the studied parameters were obtained. The prognosis of each variable adjusted for age was evaluated through Cox proportional hazard models and R2 percent (R2%) and V index (V6) were used as measures of the predictive accuracy of events of each of these variables. Receiver operating characteristic (ROC) curves from logistic regression models were used to determine the cut-offs for OUES and POUE. RESULTS: pVO(2): 20.5±5.9; percentage of predicted peak VO(2): 68.6±18.2; VE/VCO(2) slope: 30.6±8.3; OUES: 1.85±0.61; POUE: 0.88±0.27. During a mean follow-up of 33.1±14.8 months, 45 (21.8%) patients died, 10 (4.9%) underwent urgent heart transplantation and in three patients (1.5%) a left ventricular assist device was implanted. All variables proved to be independent predictors of this combined event; however, VE/VCO2 slope was most strongly associated with events (HR 11.14). In this population, POUE was associated with a higher risk of events than OUES (HR 9.61 vs. 7.01), and was also a better predictor of events (R2: 28.91 vs. 22.37). CONCLUSION: POUE was more strongly associated with death, urgent heart transplantation and implantation of a left ventricular assist device and proved to be a better predictor of events than OUES. These results suggest that this new parameter can increase the prognostic value of CPET in patients with CHF.

European gendarmerie force

Relatório de Estágio apresentado para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ciência Política e Relações Internacionais, na variante de Estudos Europeus