JVG9, a benzimidazole derivative, alters the surface and cytoskeleton of Trypanosoma cruzi bloodstream trypomastigotes

Trypanosoma cruzi has a particular cytoskeleton that consists of a subpellicular network of microtubules and actin microfilaments. Therefore, it is an excellent target for the development of new anti-parasitic drugs. Benzimidazole 2-carbamates, a class of well-known broad-spectrum anthelmintics, have been shown to inhibit the in vitro growth of many protozoa. Therefore, to find efficient anti-trypanosomal (trypanocidal) drugs, our group has designed and synthesised several benzimidazole derivatives. One, named JVG9 (5-chloro-1H-benzimidazole-2-thiol), has been found to be effective against T. cruzi bloodstream trypomastigotes under both in vitro and in vivo conditions. Here, we present the in vitro effects observed by laser scanning confocal and scanning electron microscopy on T. cruzi trypomastigotes. Changes in the surface and the distribution of the cytoskeletal proteins are consistent with the hypothesis that the trypanocidal activity of JVG9 involves the cytoskeleton as a target.

Isolation and identification of actin-binding proteins in Plasmodium falciparum by affinity chromatography

The invasion of the erythrocyte by Plasmodium falciparum depends on the ability of the merozoite to move through the membrane invagination. This ability is probably mediated by actin dependent motors. Using affinity columns with G-actin and F-actin we isolated actin binding proteins from the parasite. By immunoblotting and immunoprecipitation with specific antibodies we identified the presence of tropomyosin, myosin, a-actinin, and two different actins in the eluate corresponding to F-actin binding proteins. In addition to these, a 240-260 kDa doublet, different in size from the erythrocyte spectrin, reacted with an antibody against human spectrin. All the above mentioned proteins were metabolically radiolabeled when the parasite was cultured with 35S-methionine. The presence of these proteins in P. falciparum is indicative of a complex cytoskeleton and supports the proposed role for an actin-myosin motor during invasion.

Metaloproteinasas en placas de endarterectomía carotídea: actividad aumentada en áreas de estenosis crítica / Metalloproteinase in carotid endarterectomy plaques: increased activity in critical stenosis zones

The presence of metalloproteinases in etherosclerotic plaques has been described but their role is not well understood. An increased secretion of these proteolytic enzymes could explain plaque instability and distal embolization. Plaque were divided in 1 segment with and 1 segement without stenosis, the latter being used as control. Both segments were incubated in culture media for 48 h or were fixed for histology. The conditioned medium was studied using gelatin zimography and digital densitometry. Melloproteinases were identified by their molecular weight, inhibition with EDTA or Western blot. Standard histologic study and immunohistochemistry were done. In stenotic areas, metalloproteinase 9 (92kD) secretion was 269 percent higher than in regular plaques (191 and 73 kilopixels/ug protein respectively p<0.02). The histological study of stenotic areas showed macrophage infiltration and neoformation of blood vessels. The increased secretion of cellular matrix degrading enzyme metalloproteinase 9 in stenotic areas of atherosclerotic plaques could axplain plaque instability and subsequent embolization