Growth arrest and morphological changes triggered by emodin on Trypanosoma cruzi epimastigotes cultivated in axenic medium.

Emodin is an anthraquinone obtained from Rheum palmatum rootstocks. Here we tested the cytotoxic effects of emodin on Trypanosoma cruzi epimastigotes, as well as the morphological changes that were induced by this compound in the parasite. Emodin was permeable and blocked in vitro cell division of T. cruzi epimastigotes in axenic medium, causing growth arrest in a dose-dependent but reversible manner. Emodin-exposed epimastigotes underwent duplication of organelles, such as the nucleus, kinetoplast and flagellum, but were incapable of completing cytokinesis. Neither elongation of the parasite body nor appearance of the regular longitudinal cleavage furrow was displayed, suggesting that emodin is most likely affecting components of the parasite cytoskeleton. Moreover, drug-treated parasites acquired alterations such as protuberances, folds and indentations on their membrane surface. Since emodin has been shown to be a potent protein kinase CK2 inhibitor, and we have previously described an association between tubulin and CK2 in T. cruzi epimastigotes (De Lima et al. Parasitology132, 511-523, 2006), we also measured the indirect effect of the drug on tubulin. Incubation of epimastigotes with axenic medium containing emodin hindered the endogenous phosphorylation of tubulin in whole-cell parasite extracts. All our results suggested that the parasite CK2 may be important for the maintenance of the morphology and for the regulation of mitosis-cytokinesis transition in T. cruzi epimastigotes.

Morfometría Comparativa de Cinco Aislados Venezolanos Trypanosoma vivax / Comparative Morfometric of five Venezuelan Trypanosoma vivax isolates

La tripanosomosis causada por Trypanosoma vivax, se encuentra distribuida en las regiones tropicales y subtropicales de África, América Latina y Asia, causando grandes pérdidas económicas. Los análisis biométricos previos reportan que T. vivax mide entre 18 y 31 µm; sin embargo, pocos estudios de este tipo se han realizado en Venezuela. El objetivo del presente estudio fue describir y comparar la morfometría de cinco aislados de T. vivax, con el propósito de demostrar la variabilidad en el tamaño de los protozoarios obtenidos a partir de bovinos con infecciones activas en diferentes zonas geográficas del país. Para ello, se realizaron infecciones experimentales en ovinos y se tomaron muestras de sangre en el primer pico de parasitemia. Se registraron microfotografías de los estadios hematozoicos (20 micrografías de microscopia electrónica de barrido) de cada aislado para estudios morfológicos. Los resultados revelaron diferencias significativas (p<0,05); (p<0,01) en la longitud entre los aislados. Los valores totales promedios fueron: 20,99 ± 2,10 µm, con variaciones medias entre 18,12 ± 4,42 µm en los de menor tamaño y 24,35 ± 5,55 µm en la mayor longitud, respectivamente. Por lo tanto, se demostró la existencia de variabilidad en el tamaño de estos hemoparásitos de Venezuela.

Trypanosomosis caused by Trypanosoma vivax (T. vivax), is distributed in tropical and subtropical regions of Africa, Latin America and Asia, causing great economic losses. Previous biometric analysis report that T. vivax measures between 18 and 31 µm; but few such studies have been conducted in Venezuela. The aim of this study was to describe and compare the morphometry of five isolates of T. vivax, to demonstrate the variability in size of the protozoa obtained from naturally-infected cattle in different geographical areas of Venezuela. To accomplish this, experimental infections were induced in sheep and blood samples were taken at the first peak of parasitemia. Micrographs of stages of hematozoa (20 micrographs of each specimen using scanning electron microscopy) were recorded for morphological studies. The results of this research revealed significant (p<0.05); (p<0.01) statistical differences in length among them. The total average length was 20.99 ± 2.10 µm, with variations which ranged from 18.12 ± 4.42 µm, for smaller lengths, and 24.35 ± 5.55 µm, for greater lengths, respectively. Therefore, the existence of variability in the size of these hemoparasites in Venezuela was demonstrated.

Disruption of the intestinal barrier and bacterial translocation in an experimental model of intestinal obstruction

Clinical evidence and the use of experimental models in laboratory animals indicate that the intestine is a reservoir of microorganisms that can cause systemic infection in the human. The purpose of this work was to study the possible effect of intestinal obstruction (IO) on the mechanical and chemical barriers that bring protection against microorganisms crossing from the intestinal lumen towards the systemic tissues. We demonstrated that 24 hours after IO, histological and ultrastructural alterations do occur, seriously compromising the structure of the intestinal barrier in 100 per cent of the studies animals. Likewise, it was observed that during the same period, microorganisms translocation from intestine to the peritoneal cavity and liver (100 and 80 per cent respectively) occurred. The lungs were spared. Changes observed in the intestinal epithelium are related to a process similar to that produced by intestinal ischemia: mitochondrial destruction, with subsequent decrease of its capacity to supply eb

Identificación ultraestructural de Ehrlichia sp en un perro de Venezuela infectado experimentalmente / Ultraestructural identification of Ehrlichia spïin experimental infected dog from Venezuela

El presente estudio constituye el primer reporte en Venezuela de las características ultraestructurales de Ehrlichia sp en células mononucleares de sangre periférica en un perro infectado experimentalmente, utilizándose para ello microscopía electrónica de transmisión. El animal desarrolló manifestaciones clínicas características de la infección y al realizar los extendidos sanguíneos coloreados con Giemsa modificado, se observaron al microscopio de luz las inclusiones intracitoplasmáticas características en células mononucleares. Al microscopio electrónico se evidenciaron microorganismo extremadamente pleomórficos que se corresponden con los cuerpos elementales dentro de vacuolas citoplasmáticas, rodeados por una doble membrana, cada uno constituido por gránulos electrodensos, características ultraestructurales que identifican al género Ehrlichia

Tipicidad y atipicidad del eritema discromico perstans / Typical and aty[ical erythema dyschromicum perstans

Los autores evalúan un grupo de pacientes (49), referidos en los últimos 10 años con el diagnóstico clínico de Eritema Discrómico Perstans a la consulta externa del Hospital Vargas (Instituto de Biomedicina). Se tomaron los siguientes parámetros: clínico, histopatológico, M. electrónica, subpoblaciones celulares en tejido, inmunofluorescencia, anticuerpos antinucleares y otros exámenes paraclínicos. Todos estos parámetros fueron tomados en cuenta con la finalidad de precisar aquellos pacientes con EDP típico en contraposición con aquellos pacientes atípico. Hacen consideraciones para reconocer el EDP típico como una entidad aparte, mientras que los pacientes con EDP atípico podrían ser una expresión de otra nosología