Comportamento evolutivo de extrassístoles ventriculares por provável hiper automatismo em adolescente. Quando o seguimento clínico é melhor que a intervenção. / Evolutionary behavior of ventricular extrasystoles due to probable hyperautomatism in adolescents. When clinical follow-up is better than intervention

INTRODUÇÃO: As extrassístoles ventriculares (EVs) em adolescentes são fenômenos relativamente frequentes e podem apresentar densidade menor do que em fases de infância e pré- -puberdade. Dados de literatura sugerem que durante a puberdade há redução da densidade de ectopias ventriculares, principalmente quando o mecanismo arrítmico é atividade deflagrada ou hiper automatismo. A atividade deflagrada apresenta como característica o período de acoplamento fixo e habitualmente remissão no pico do esforço com exacerbação da arritmia na fase de recuperação do teste ergométrico. O hiper automatismo apresenta o mesmo comportamento na maioria dos casos, podendo ser diferenciado pelo acoplamento variável durante a monitorização de Holter, caracterizando um foco Parassistólico que não depende do batimento anterior para ocorrer. OBJETIVO: Descrever o quadro clínico de uma adolescente com EVs frequentes com comportamento parassistólico, que apresenta uma densidade arrítmica em redução após o término da puberdade. DESCRIÇÃO DO CASO: Adolescente, feminina, 19 anos, com histórico de palpitações frequentes na infância. Iniciou acompanhamento por quadro de EVs com morfologia de origem na via de saída do ventrículo direito em provável posição póstero lateral na via de saída. Análise ecocardiográfica e de ressonância magnética não evidenciava alterações estruturais no coração. O Holter de 24 horas demonstrava EVs frequentes em processo de redução na evolução (figuras 1 e 2). O teste ergométrico evidenciava EVs com melhora da densidade arrítmica no pico do esforço. Análise detalhada da eletrocardiografia dinâmica demonstrava período de acoplamento variável, denotando a possibilidade de hiper automatismo com EVs de acoplamento variável. Durante a evolução clínica houve melhora das queixas de palpitação e redução da densidade de ectopias em relação a admissão em nosso serviço aos 12 anos de idade (ainda pré menarca). CONCLUSÃO: Arritmias ventriculares, em pacientes jovens e sem cardiopatia estrutural, podem apresentar redução ou remissão espontânea; a avaliação do acoplamento entre o batimento antecessor e a extrassístole pode ajudar a descartar batimentos de maior risco (acoplamento curto) e indicar hiper automatismo como nos casos de acoplamento variável (figuras 1 e 2); a remissão das extrassístoles no pico do esforço indica um critério de benignidade para remissão ou redução da densidade arrítmica após o termino do desenvolvimento corpóreo.

Effects of Grain Boundary Misorientation Angle on the Mechanical Behavior of Al Bicrystals.

This research article explores the effect of grain boundary (GB) misorientation on the mechanical behavior of aluminum (Al) bicrystals by means of molecular dynamics (MD) simulations. The effect of GB misorientation on the mechanical properties, fracture resistance, and crack propagation are evaluated under monotonic and cyclic load conditions. The J-integral and the crack tip opening displacement (CTOD) are assessed to establish the effect of the GB misorientation angle on the fracture resistance. The simulations reveal that the misorientation angle plays a significant role in the mechanical response of Al bicrystals. The results also evidence a gradual change in the mechanical behavior from brittle to ductile as the misorientation angle is increased.

Does rassi score caracterize patients with chagas disease with complex ventricular arrhythmias?

INTRODUCTION: Rassi score (NYHA functional class III/IV HF [5 points], cardiomegaly [5 points], contractions abnormalities [3 points], non-sustained ventricular tachycardia [3 points], low amplitude QRS [2 points] and male sex [2 points]) is used in the clinic for risk stratification due to cardiovascular death in patients with Chagas disease (P-CD). Whether this score has any role in identifying patients at risk of complex ventricular arrhythmias has not been determined. OBJECTIVE: Assess whether there is an association between Rassi score and the presence of potentially malignant complex ventricular arrhythmias in P-CD. METHODS: 79 P-CD (34 men, age 61±11 years-old), consecutively referred for 24h-Holter were divided into 2 groups: low risk Rassi score (57 P, 0-6 points) and medium-high risk (22 P, 7-20 points). The amount and complexity of ventricular arrhythmia (> 30/ h, ventricular tachycardia [VT]), LVEF, heart rate turbulence (HRT) indexes (turbulence onset [TO] and turbulence slope [TS]) and HRT category (0 [without disautonomy], 1 and/or 2 [presence of disautonomy]) were evaluated. RESULTS: Compared to P-CD with low risk score, those with medium-high risk had more ventricular arrhythmias, lower LVEF, worse HRT indexes and more HRT categories 1 and/or 2 (see table below). CONCLUSIONS: 1) P-CD and Rassi score of medium to high risk have a greater amount of ventricular arrhythmias; 2) These findings can be explained by the presence of greater degree of disautonomy, assessed by HRT, and by the lower LVEF; 3) Prospective studies are necessary to confirm these findings in clinical practice.

Design of titanium uncemented femoral stems for hip prosthesis suitable for the Colombian young adult population.

The increase of revision surgeries in hip replacement procedure in Colombian young adult population can be addressed by a new design of femoral stem that reduces stress shielding. A new femoral stem was designed using topology optimization as a design aid to reduce the mass in the femoral stem and its overall stiffness, combined with the theoretical, computational, and experimental assessment of the new design that complies with a static and fatigue safety factor greater than one. The new femoral stem design can be used as a design tool to reduce the number of revision surgeries caused by stress shielding.

Crack Length Effect on the Fracture Behavior of Single-Crystals and Bi-Crystals of Aluminum.

Molecular dynamics simulations of cracked nanocrystals of aluminum were performed in order to investigate the crack length and grain boundary effects. Atomistic models of single-crystals and bi-crystals were built considering 11 different crack lengths. Novel approaches based on fracture mechanics concepts were proposed to predict the crack length effect on single-crystals and bi-crystals. The results showed that the effect of the grain boundary on the fracture resistance was beneficial increasing the fracture toughness almost four times for bi-crystals.

Influence of Density-Based Topology Optimization Parameters on the Design of Periodic Cellular Materials.

The density based topology optimization procedure represented by the SIMP (Solid isotropic material with penalization) method is the most common technique to solve material distribution optimization problems. It depends on several parameters for the solution, which in general are defined arbitrarily or based on the literature. In this work the influence of the optimization parameters applied to the design of periodic cellular materials were studied. Different filtering schemes, penalization factors, initial guesses, mesh sizes, and optimization solvers were tested. In the obtained results, it was observed that using the Method of Moving Asymptotes (MMA) can be achieved feasible convergent solutions for a large amount of parameters combinations, in comparison, to the global convergent method of moving asymptotes (GCMMA) and optimality criteria. The cases of studies showed that the most robust filtering schemes were the sensitivity average and Helmholtz partial differential equation based filter, compared to the Heaviside projection. The choice of the initial guess demonstrated to be a determining factor in the final topologies obtained.

Relación entre el índice de masa corporal bajo previo al embarazo y el riesgo de parto prematuro / Relationship between low body mass index before pregnancy and the risk of preterm birth

Resumen OBJETIVOS: identificar si existe relación entre el índice de masa corporal bajo previo a la concepción y el riesgo de parto pretérmino y de ruptura prematura de membranas pretérmino. MATERIALES Y MÉTODOS: estudio transversal, analítico, de una muestra al azar de pacientes atendidas entre enero de 2015 y enero de 2016. Variables de estudio: edad, índice de masa corporal, ganancia ponderal durante el embarazo, antecedentes de infección de vías urinarias, cervicovaginitis, amenaza de aborto y ruptura prematura de membranas. El análisis se efectuó con un modelo de regresión lineal generalizada para identificar la influencia del índice de masa corporal y del resto de las variables estudiadas en el riesgo de parto prematuro. RESULTADOS: se analizaron los datos de 120 pacientes y la regresión lineal generalizada mostró una relación estadísticamente significativa entre el índice de masa corporal previo al embarazo y el riesgo de parto pretérmino (r2 = 0.016, p = < 0.001). CONCLUSIONES: el IMC bajo, previo al embarazo, se relaciona con aumento poco importante del riesgo de parto pretérmino; el riesgo de ruptura prematura de membranas se incrementa discretamente en pacientes con antecedente de amenaza de aborto y ruptura prematura de membranas pretérmino.

Abstract OBJECTIVE: To identify if there is a relationship between the low pre-conceptional body mass index and the risk of preterm delivery and / or PROM. MATERIALS AND METHODS: Analytical cross-sectional study was conducted with a random sample of 120 patients treated between January 2015 to January 2016. Patients were analyzed for age, body mass index, and weight gain during pregnancy, history of urinary tract infection, vaginal infections, threat of abortion and premature rupture of membranes. The analysis was performed using a generalized linear regression model to identify the influence of body mass index and the rest of the variables studied on the risk of preterm delivery. RESULTS: The generalized linear regression showed a statistically significant relationship between the pre gestational body mass index and the risk of preterm delivery. (R2 = 0.016, p = <0.001) CONCLUSION: Body mass index influenced the risk of preterm delivery but not premature rupture of preterm membranes.

[Prognosis of nephrosis]. / Pronóstico de la nefrosis.

Renal biopsy, the introduction of immunohistologic methods and electron microscopy have allowed the differentiation of clinicopathologic entities associated to nephrotic syndrome. Two main categories must be differentiated: in the first, diffuse lesions of the glomerulus, including those secondary to specific diseases the same as those that are apparently primary, are responsible for the increased permeability of glomerular capillaries. Any one of the following clinical signs suggests this category: acute onset with nephritic syndrome, moderate nephritic syndrome, moderate nephrotic syndrome, gross hematuria, persistent hypertension and/or renal failure, poor selectivity of proteinuria and drop in complement serum levels (C3). In the second category, known as idiopathic nephrotic syndrome, the mechanism of disorder of the glomerular capillary is unknown and the nephrotic syndrome is more marked. In most cases with idiopathic nephrotic syndrome, minimal glomerular lesions (MGL) are present. The clinicopathologic correlation among these three types of lesions shows that the type with MGL is characterized by selective proteinuria, absence of hematuria, good response to corticosteroids and good outlook; whereas in types with diffuse mesangial proliferation (DMP) and segmentary sclerosis, proteinuria is frequently non selective, hematuria shows in 50 to 75% of the patients; prognosis is poor. However, MGL, DMP and focal segmentary glomerular sclerosis are not different entities, but represent variants of the same disease. Considering that corticosensitive nephrosis to this moment is the most common cause of the nephrotic syndrome, especially in children under 8 years, renal biopsy should be done only under two circumstances: a) when the clinical symptoms suggest diffuse glomerular lesions and b), when resistance to corticosteroids becomes evident.

Isolation of a hypotensive substance from seeds of Casimiroa edulis.

The hypotensive activity of the alcoholic and aqueous extracts of C. edulis has been previously reported. The present paper describes the pharmacological studies of a substance isolated from the alcoholic extract. Preliminary chemical and pharmacological data allowed a histamine-like compound to be proposed as the hypotensive principle. Studies were performed by means of in vitro and in vivo animal experiments.