Chagas' myocardiopathy, caused by the intracellular protozoan Trypanosoma cruzi, is characterized by microvascular alterations, heart failure and arrhythmias. Ischemia and arrythmogenesis have been attributed to proteins shed by the parasite, although this has not been fully demonstrated. The aim of the present investigation was to study the effect of substances shed by T. cruzi on ischemia/reperfusion-induced arrhythmias. We performed a triple ischemia-reperfusion (I/R) protocol whereby the isolated beating rat hearts were perfused with either Vero-control or Vero T. cruzi-infected conditioned medium during the different stages of ischemia and subsequently reperfused with Tyrode's solution. ECG and heart rate were recorded during the entire experiment. We observed that triple I/R-induced bradycardia was associated with the generation of auricular-ventricular blockade during ischemia and non-sustained nodal and ventricular tachycardia during reperfusion. Interestingly, perfusion with Vero-infected medium produced a delay in the reperfusion-induced recovery of heart rate, increased the frequency of tachycardic events and induced ventricular fibrillation. These results suggest that the presence of parasite-shed substances in conditioned media enhances the arrhythmogenic effects that occur during the I/R protocol.

By this study we seek the expectable range of waist circumference (WC) for every degree of body mass index (BMI), which will serve to studies targeting ascertaining the health risk. We studied 2,932 patients (39.6% men and 60.4% women, between 18 and 96 years ) of the same ethnic group who consecutively attended outpatient departments of our clinics between 2000 and 2004.. BMI correlated linearly with the WC (cc: 0.85; p < 0.001). The men, the obese, and diabetics were older (p < 0.001). BMI was greater in women and WC in men. The women had a greater WC if they had diabetes (p < 0.01), being equal to diabetic males. The men had greater WC when they had diabetes (p < 0.001). Waist at risk was detected (men > = 102 cm and women > = 88 cm) in 94.3% of the obese, in 32.3% of overweight patients, in 3.8% of patients with BMI < 25, in 84.3% of diabetics, and in 72.6% of patients without diabetes. We made graphic standardisation of WC with regard to BMI, and we calculated the percentiles 10, 25, 50, 75 and 90, grouping in ranges of 2 kg/m² of BMI. The diabetic patients are grouped in ranges of 4 kg/m². As conclusion we present a standardisation of the WC measurement of patients attended to in our Endocrinology and Nutrition practices distributed in percentiles as a clinically usable tool to define the ranges of WC for every BMI value.

En este estudio hemos buscado el rango de circunferencia de cintura (WC) para cada grado de índice de masa corporal (BMI), que sirva para estudios que determinen riesgos de salud. Estudiamos 2.932 pacientes (39,6% varones y 60,4% mujeres, entre 18 y 96 años) del mismo grupo étnico que consecutivamente asistieron a consultas externas de nuestras clínicas entre 2000 and 2004. El BMI correlacionó linealmente con la WC (cc: 0,85; p < 0,001). Eran mayores los varones, los obesos y los diabéticos. El BMI era mayor en mujeres y la WC en varones. Las mujeres tenían mayor WC si eran diabéticas (p < 0,01), igualando a los hombres. Los varones tenían mayor WC si eran diabéticos (p < 0,001). La circunferencia de riesgo (varones > = 102 cm y mujeres > = 88 cm) la presentaban el 94,3% de los obesos, el 32,3% de los pacientes con sobrepeso y el 3,8% de pacientes con BMI < 25, el 84,3% de diabéticos y el 72,6% de pacientes sin diabetes. Elaboramos una estandarización gráfica de WC en relación con BMI y calculamos los precentiles 10, 25, 50, 75 y 90, agrupados en rangos de 2 kg/m² de BMI. Como el número de diabeticos es menor, los agrupamos en rangos de 4 kg/m². En conclusión presentamos una estandarización de la WC de pacientes atendidos en nuestra consulta de endocrinología y nutrición distribuidos en percentiles como herramienta utilizable clínicamente para definir rangos de WC para cada valor de BMI.