Dimorfismo sexual de la leptina, resistencia a la insulina y composición corporal en prepúberes normopeso / Leptin sexual dimorphism, insulin resistance, and body composition in normal weight prepubescent

INTRODUCCIÓN: La etapa prepuberal es un periodo crítico del desarrollo de la grasa corporal, en el cual la leptina y la resistencia a la insulina han sido asociados, sin embargo, hay pocos estudios en prepúberes normo- peso. OBJETIVO: Evaluar la relación de leptina con composición corporal y resistencia a la insulina en un grupo de prepúberes normopeso. PACIENTES Y MÉTODO: Estudio transversal analítico en 128 pre púberes saludables, normopeso, entre 6 y 10 años. Se midieron, talla, peso, índice de masa corporal (IMC), porcentaje de grasa corporal (PGC), perímetro abdominal (PA) y perímetro de cadera (PC). Se determinó leptina (ng/ml) e Insulina (μU/L) en plasma por inmunoensayo y glicemia (mmol/L) por método enzimático. Se calculó HOMA-IR. Se hizo análisis de comparación y de correlación por sexo. RESULTADOS: Se confirmó en niñas un mayor nivel de leptina (6,8 ± 5 vs 3,3 ± 3,7; p = 0,000), insulina (7,1 ± 4,5 vs 5,2 ± 2,5; p = 0,016), PGC (22,4 ± 4,3 vs 18,6 ± 3,9; p = 0,000) y PC (67 ± 5,7 vs 65,0 ± 4,5; p = 0,019), y un menor índice cintura/cadera (0,84 ± 0,04 vs 0,88 ± 0,04; p = 0,000) comparado con varones. Las correlaciones de leptina con variables antropométricas fueron signifi cantes en ambos sexos, con mayor asociación en sexo femenino. La asociación del HOMA-IR con la leptina fue similar en ambos sexos. CONCLUSIONES: En prepúberes normopeso de 6 a 10 años, hay diferencias por sexo en adiposidad y en niveles de leptina, no asociadas con diferencias en el IMC ni en la resistencia a la insulina. La mayor asociación de leptina con adiposidad en las niñas podría estar relacionada con una elevada tasa de adipogénesis inducida por esta hormona.

INTRODUCTION: The prepubertal stage is a critical period of body fat development, in which leptin and insulin re sistance has been associated, however, there are few studies in normal-weight prepubescents. OBJECTIVE: To assess the relationship between leptin and body composition and insulin resistance in a group of normal-weight prepubescents. PATIENTS AND METHOD: Analytical cross-sectional study with 128 healthy prepubescents of normal weight, aged between 6 and 10 years. Height, weight, body mass index (BMI), body fat percentage (BFP), waist circumference (WC), and hip circumference (HC) were measured. Plasma leptin (ng/mL) and insulin (mU/L) were evaluated by immunoassay and glycemia (mmol/L) by enzymatic method. HOMA-IR was calculated. A comparison study and correlation analysis by sex were performed. RESULTS: Females presented higher values than males of leptin (6.8 ± 5 vs 3.3 ± 3.7; p = 0.000), insulin (7.1 ± 4.5 vs 5.2 ± 2.5; p = 0.016), BFP (22.4 ± 4.3 vs 18.6 ± 3.9; p = 0.000), and HC (67 ± 5.7 vs 65.0 ± 4.5; p = 0.019), and a lower waist/hip ratio (0.84 ± 0.04 vs 0.88 ± 0.04; p = 0.000). Leptin correlations with anthropometric variables were significant in both sexes, with greater association in females. The association of HOMA-IR with leptin was similar in both sexes. CONCLUSIONS: in normal-weight prepubescents aged between 6-10 years, there are sex differences in adiposity and leptin levels not associated with differences in BMI or insulin resistance. The greater association of leptin with adiposity in girls could be related to a high rate of adipogenesis induced by this hormone.

[Leptin sexual dimorphism, insulin resistance, and body composition in normal weight prepubescent]. / Dimorfismo sexual de la leptina, resistencia a la insulina y composición corporal en prepúberes normopeso.

INTRODUCTION: The prepubertal stage is a critical period of body fat development, in which leptin and insulin re sistance has been associated, however, there are few studies in normal-weight prepubescents. Ob jective: To assess the relationship between leptin and body composition and insulin resistance in a group of normal-weight prepubescents. PATIENTS AND METHOD: Analytical cross-sectional study with 128 healthy prepubescents of normal weight, aged between 6 and 10 years. Height, weight, body mass index (BMI), body fat percentage (BFP), waist circumference (WC), and hip circumference (HC) were measured. Plasma leptin (ng/mL) and insulin (mU/L) were evaluated by immunoassay and glycemia (mmol/L) by enzymatic method. HOMA-IR was calculated. A comparison study and correlation analysis by sex were performed. RESULTS: Females presented higher values than males of leptin (6.8 ± 5 vs 3.3 ± 3.7; p = 0.000), insulin (7.1 ± 4.5 vs 5.2 ± 2.5; p = 0.016), BFP (22.4 ± 4.3 vs 18.6 ± 3.9; p = 0.000), and HC (67 ± 5.7 vs 65.0 ± 4.5; p = 0.019), and a lower waist/hip ratio (0.84 ± 0.04 vs 0.88 ± 0.04; p = 0.000). Leptin correlations with anthropometric variables were significant in both sexes, with greater association in females. The association of HOMA-IR with leptin was similar in both sexes. CONCLUSIONS: in normal-weight prepubescents aged between 6-10 years, there are sex differences in adiposity and leptin levels not associated with differences in BMI or insulin resistance. The greater association of leptin with adiposity in girls could be related to a high rate of adipogenesis induced by this hormone.

INFLUENCE OF TEMPERATURE ON THE AVERAGE VELOCITY OF MUSCLE FATIGUE IN Rhinella marina SARTORIUS / Influencia de la temperatura en la velocidad promedio de la fatiga muscular en el sartorio de rhinella marina

Abstract Objective: To analyze and compare the effect of temperature on the average velocity of the linear phase and the exponential phase stages produced by periodic stimulation with simple twitching or with tetanus in the toad sartorius. Methods: an in vitro experimental study with a sample of 46 toad sartorius muscles randomly selected. At the temperatures studied, peak tension produced with two stimulus patterns (twitching and tetanus) were measured until reaching the corresponding muscle fatigue in each case. The tension velocity drop in the linear phase and the exponential phase for each type of fatigue were calculated, and the regression slopes obtained with the Arrhenius equation were compared. Results: The temperatures used (1 to 12°C) significantly affected the velocity of fatigue in the stages of linear and exponential phases of both types of fatigue (p <0.05). The function of which the fatigue curves were adjusted to the temperatures used was similar to the function used with the curves at room temperature. When comparing the slopes of Arrhenius regression in the exponential phase and the different stages of the linear phase of each fatigue and between both fatigues, no significant differences were found (p>0.05). Conclusions: The temperature significantly affected average development velocity of fatigue in the different phases of the two types of fatigue, but when comparing slopes of most regressions corresponding to Arrhenius there were no significant differences, suggesting that the mechanisms underlying the different stages of fatigue have equal sensitivity to temperature.

Resumen Objetivos: Analizar y comparar el efecto de la temperatura en la velocidad promedio de las etapas de la fase lineal y de la fase exponencial de la fatiga producida por estimulación periódica con sacudida simple o con tétanos en el sartorio de sapo. Métodos: Estudio experimental, in vitro; muestra: 46 músculos de sartorio de sapo seleccionados aleatoriamente. A las temperaturas estudiadas, se midió la tensión pico producida con dos patrones de estímulo (sacudida simple o tétanos) hasta llegar en cada caso a un tipo de fatiga muscular, se calculó la velocidad de caída de la tensión en las etapas de la fase lineal y en la fase exponencial de cada tipo de fatiga y se compararon las pendientes de las regresiones obtenidas con la ecuación de Arrhenius. Resultados: Las temperaturas utilizadas (1 a 12°C) afectaron significativamente (p<0,05) la velocidad de la fatiga en las etapas de las fases lineal y exponencial de ambos tipos de fatiga. La función con que se ajustaron las curvas de fatiga a las temperaturas usadas fue similar a la usada con las curvas a temperatura ambiente. Al comparar entre las pendientes de las regresiones de Arrhenius de la fase exponencial y las diferentes etapas de la fase lineal de cada una de las fatigas y entre ambas fatigas, no hubo diferencias significativas (p>0,05). Conclusiones: La temperatura afectó significativamente la velocidad promedio de desarrollo de la fatiga en las diferentes fases de los dos tipos de fatiga, pero al comparar las pendientes de la mayoría de las regresiones correspondientes de Arrhenius, no se encontraron diferencias significativas, lo cual sugiere que, los mecanismos que subyacen a las diferentes etapas de la fatiga tienen igual sensibilidad a la temperatura.

Efecto del ejercicio y reposo postintervención sobre variables de riesgo cardiovascular en grupo de escolares / Effect of exercise and a post-intervention rest in cardiovacular risk variables in schoolars / Efeitos de exercicios e do repouso pos-operatorio sobre variaveis de risco cardiovascular em grupo de escolares

Objetivo: determinar el efecto de un programa de ejercicio seguido de un periodo de reposo post-intervención en marcadores de riesgo cardiovascular de un grupo de escolares de un Colegio de Cali-Colombia. Materiales y métodos: estudio experimental en el que se incluyeron 26 escolares con edades entre 10 y 13 años. Estos se sometieron a un período (4 meses) de intervención con ejercicio seguido de un periodo de reposo. Cambios en: glucosa y perfil lipídico; variables antropométricas; y parámetros de capacidad física, fueron evaluados. Resultados: los niños mostraron mayores valores de porcentaje (%) grasa corporal, cHDL, VO2max, carga y lactato al finalizar la intervención con ejercicio, e incremento significante en el valor de glicemia, IMC y % grasa corporal respecto al final del periodo de reposo post-intervención. En las niñas solo se observó incremento en la mediana de la carga luego de intervención con ejercicio. En el periodo de reposo post-intervención el IMC, porcentaje de grasa corporal y glicemia fueron más altos, y el valor de carga menor en comparación con el final de la intervención con ejercicio. Conclusiones: los niños presentaron mejor respuesta al ejercicio en variables relacionadas con riesgo cardiovascular, y este hallazgo podría estar influenciado por actividad física espontanea en los varones. En la mayoría de variables se observaron cambios negativos tras el periodo de reposo post-intervención. Para el conocimiento de los autores, este ensayo representa una primera exploración del efecto de un periodo sedentario tras un programa de ejercicio en el perfil cardiovascular de un grupo de escolares.

Objective: to determine the effect of an exercise program followed by a rest period post-intervention on cardiovascular risk markers in a group of children of Cali-Colombia school. Materials: experimental study which included 26 children aged 10-13 years old. These were subjected to a exercise intervention period (4 months) followed by a rest period. Changes in: glucose and lipid profile, anthropometric variables, and parameters of physical capacity, were evaluated. Results:boys showed higher values of body fat percentage, cHDL, VO2max, load and lactate at the end of the exercise intervention, and significant increase in the value of blood glucose, BMI and body fat percentage at the end of the post-intervention rest period. In girls only was observed an increase in load median after exercise intervention. In the post-intervention rest period BMI, body fat percentage and blood glucose were higher and the load value was lower compared to the end of the exercise intervention. Conclusions: boys had a better response to exercise in variables related to cardiovascular risk, and this finding could be influenced by spontaneous physical activity in men. In most of the variables, negative changes were observed after the post-intervention rest period. To the author’s knowledge, this paper represents a first exploration of the effect of a sedentary period after an exercise program on the cardiovascular profile of a schoolchildren group.

Objetivo: determinar o efeito de um programa de exercícios seguidos por um período de pós-intervenção nos marcadores de risco cardiovascular em um grupo de resto escolares de Cali Colombia.Materiais: estudo experimental em que 26 alunos foram incluídos com idades entre 10 e 13 anos. Estes foram submetidos a um período (4 meses ), seguido intervenção de exercício com um período de descanso. Mudanças: glicose e do perfil lipídico; variáveis antropométricas ; e foram avaliados parâmetros de capacidade física Resultado: as crianças apresentaram maior percentagem (%) de gordura corporal, o cHDL, VO2max, de carga e de lactato no final da intervenção de exercício, e aumento significativo na quantidade de glicose, imce % de gordura corporal em comparação com o fim de período de descanso pós-intervenção. Em raparigas foi observado aumento apenas no meio de carga, após a intervenção do exercício. No período de descanso pós-intervenção imc, percentual de gordura e de glicose no sangue foram maiores e menor valor de carga em relação ao final da intervenção de exercícios.Conclusões: as crianças apresentaram melhor resposta ao exercício em variáveis relacionadas ao risco cardiovascular, e este achado poderia ser influenciada pela atividade física espontânea em homens. Na maioria das variáveis foram observadas variações negativas depois do período de descanso pós-intervenção. Para o conhecimento dos autores , este estudo representa a primeira análise do efeito de um período sedentário após um programa de exercício no perfil cardiovascular de um grupo de crianças em idade escolar

Disfunción muscular respiratoria: una entidad multicausal en el paciente críticamente enfermo sometido a ventilación mecánica / Respiratory Muscle Dysfunction: A Multicausal Entity in the Critically Ill Patient Undergoing Mechanical Ventilation

Es probable que la disfunción de los músculos respiratorios, principalmente del diafragma, constituya una pieza clave dentro de los mecanismos fisiopatológicos que conducen a la dificultad del destete de la ventilación mecánica. La limitada movilidad del paciente crítico -y en especial del diafragma- cuando se requiere soporte prolongado con ventilación mecánica favorece el inicio temprano de la disfunción muscular respiratoria, la cual puede originarse también o hacerse mayor en presencia de factores frecuentes en el paciente críticamente enfermo, tales como sepsis, desnutrición, edad avanzada, duración y modo ventilatorio, uso de algunos medicamentos como glucocorticoides y bloqueadores neuromusculares. En esta revisión haremos énfasis en este origen multicausal, en el que la alteración del metabolismo de las proteínas es un mecanismo común involucrado, de acuerdo con los hallazgos reportados en diferentes modelos. El entendimiento de esta multicausalidad integrada por un mismo mecanismo fisiopatológico podría favorecer el manejo y la monitorización de los pacientes sometidos a ventilación mecánica

Respiratory muscle dysfunction, particularly of the diaphragm, may play a key role in the pathophysiological mechanisms that lead to difficulty in weaning patients from mechanical ventilation. The limited mobility of critically ill patients, and of the diaphragm in particular when prolonged mechanical ventilation support is required, promotes the early onset of respiratory muscle dysfunction, but this can also be caused or exacerbated by other factors that are common in these patients, such as sepsis, malnutrition, advanced age, duration and type of ventilation, and use of certain medications, such as steroids and neuromuscular blocking agents. In this review we will study in depth this multicausal origin, in which a common mechanism is altered protein metabolism, according to the findings reported in various models. The understanding of this multicausality produced by the same pathophysiological mechanism could facilitate the management and monitoring of patients undergoing mechanical ventilation

Respiratory muscle dysfunction: a multicausal entity in the critically ill patient undergoing mechanical ventilation.

Respiratory muscle dysfunction, particularly of the diaphragm, may play a key role in the pathophysiological mechanisms that lead to difficulty in weaning patients from mechanical ventilation. The limited mobility of critically ill patients, and of the diaphragm in particular when prolonged mechanical ventilation support is required, promotes the early onset of respiratory muscle dysfunction, but this can also be caused or exacerbated by other factors that are common in these patients, such as sepsis, malnutrition, advanced age, duration and type of ventilation, and use of certain medications, such as steroids and neuromuscular blocking agents. In this review we will study in depth this multicausal origin, in which a common mechanism is altered protein metabolism, according to the findings reported in various models. The understanding of this multicausality produced by the same pathophysiological mechanism could facilitate the management and monitoring of patients undergoing mechanical ventilation.