Veneno de Latrodectus mactans de Chile (Araneae, Theridiidae): su efecto sobre músculo liso / Venom of Latrodectus mactans from Chile (Araneae, Theridiidae): effect on smooth muscle

The venoms of Latrodectus sp. have been reported to induce contraction probably mediated by adrenergic and cholinergic transmitters. We have demonstrated that the venom of Chilean Latrodectus mactans contains neurotoxins that induce a contraction partially independent of transmitters release. Transmembrane mobility of Na+ and Ca2+ ions and more specifically, the increase of cytoplasmic calcium concentration are responsible for tonic contraction in smooth muscle. Calcium may enter the cell by several ways, such as the voltage-dependent Ca2+ L-type channels and the Na+/Ca2+ exchanger. This study aimed to examine the participation of this exchanger in the tonic contraction of smooth muscle in vas deferent of rat induced by the venom of the Chilean spider L. mactans. Blockers of Na+ channels (amiloride) and Ca2+ L-type channels (nifedipine), and a stimulator of the exchanger (modified Tyrode, Na+ 80 mM) were used. Simultaneously, variations of the cytoplasmic concentration of Ca2+ were registered by microfluorimetry (Fura-2 indicator) in the presence of nifedipine. In presence of amiloride, dose-dependent inhibition of venom-induced contraction was observed, suggesting the participation of voltage-dependent Ca2+ L-type channels. The contraction was only partially inhibited by nifedipine and the Ca2+ cytoplasmic concentration increased, as assessed by the microfluorimetric registration. Finally, the venom-induced contraction increased in the presence of modified Tyrode, probably due to the action of the Na+/Ca2+ exchanger. Taken together, our results support the idea that the Na+/Ca2+ exchanger is active and may be, at least in part, responsible for the contraction induced by the venom of Chilean L. mactans.

Análisis de los niveles de cortisol sérico en pacientes críticos con inestabilidad hemodinámica / Analysis of serum cortisol levels in critical patients with hemodynamic inestability

There is currently no consensus as to expected levels of serum cortisol (SC) in critical patients. Some authors, based on the ACTH test, consider 18 ug/dL and up as normal while others start >25-30 ug/dL. There are no reports of critical patients with Systemic Inflammatory Response Syndrome (SIRS). In this study we determine the SC in a group of critical patients with SIRS and correlate this value with the hemodynamic response and vasoactive drug requirements. SC was measured under conditions of stree defined by important hemodynamic instability within the SIRS context. We studied patients with no known history of steroid therapy nor use of other drugs that could alter the adrenal axis, and with no suspicion of adrenal failure. Enzimuntests Roche ES 300(CV 6 percent) was used. Based on our experience and on different studies, patients were classified into theree groups according to the SCvalue under stress. Group 1: SC <18 ug/dL, Group 2: SC 18,1 to 28 ug/dL, and Group 3: CS > 28 ug/dL. We studied 20 patients, 15 men and 5 women, all presenting SIRS, 17 with septic schock, 1 with severe head injuries, 1 hypovolemic shock, 1 postsurgery. The initial PA median was 80/50 mmHg. CS values varied between 10,3 and > 46 ug/dL. Group 1: 8/20 patients (40 percent) with a variation between 10,3 and 17,3 ug/dL; Group 2: 7/20 patients (35 percent) between 19,9 and 27,8 ug/dL, and Group 3: 5/20 (25 percent) between 30,8 and > 46 ug/dL. The most significant difference among groups was found in Group 1 patients who required maximun dosage of DVA and presented hemodynamic stabilization with 150 to 300 mg of hydrocortisone perc day. There were no differences between groups 2 and 3 in DVA dosage, which was lower than for Group 1, and these did not evidence hemodynamic stabilization with hydrocortisone. In conclusion: A SC level > 18 ug/dL can be expected in critical patients undergoing SIRS during periods of hemodynamic instability. 2.- SC values lower than 18 ug/dL contribute to the hemodynamic instability determined by the initial sickness, and these cases require the administration of hydrocortisone in stress dosage. 3.- Patients with cortisol levels over 18 ug/dL receive no benefits from hydrocortisone. 4.- More studies in this field are requires to establish different patterns of steroidad response in critical patients

Uso de microcomputadores en endocrinología de la reproducción / Use of microcomputers in endocrinology of the reproduction

Se presenta el método para obtener rápidamente, mediante un microcomputador y software específico, los gráficos de curvas hormonales promedio de hormona luteinizante (LH) de 15 ciclos concepcionales, en los que se determinan los valores plasmáticos de LH, de hormona folículo-estimulante (FSH), de prolactina (PRL), de estradiol (E2) y progesterona (P). Se establecen las ventajes para el investigador del uso de un sistema de informática personal

Efecto de la concentracion diaria de estradiol en las caracteristicas morfologicas del complejo cumulo-corona-ovocito obtenido en programas de fecundacion in vitro. / Effect of the daily concentration of estradiol on the morphological characteristics of the cumulus-corona-oocyte complex obtained in fertilization in vitro programs

El presente estudio analiza la relacion existente entre la concentracion diaria de estradiol en plasma y la morfologia del complejo cumulo-corona-ovocitos (CCO), obtenidos de aspiracion folicular en un programa de fecundacion in vitro (FIV). De un total de 99 ovocitos pertenecientes a 27 mujeres incorporadas en este estudio, 66% fueron morfologicamente del tipo II; 12% del tipo III, y 16% del tipo IV. El 80,6% de los ovocitos que se fertilizaron corespondian al tipo II, y 89,6% de los ovocitos que se segmentaron eran de esta misma caracterizacion morfologica. La concentracion diaria de estradiol en los dias que preceden a la aspiracion folicular supera al 100% cuando se obtienen ovocitos del tipo II. Sin embargo, en aquellos casos en que se obtienen ovocitos tipo III o IV el estradiol experimenta una estabilizacion en las 48 horas que preceden a la aspiracion folicular, y el incremento acumulativo total no sepera el 80%. Por otra parte, el aumento del volumen folicular total presenta un paralelismo con el incremento diario de estradiol. Cuando este paralelismo se quiebra, la probabilidad de encontrar ovocitos no fertilizables aumenta significativamente