Alteration in erythrocyte membrane lipids of chronic lead intoxicated male rabbits and their modulation with vitamin E

Membrane lipids specially fatty acids appear to be one of the critical target associated with lead intoxication. The aim of our research was to elucidate the changes in erythrocyte membrane fatty acids composition, cholesterol and phospholipids [that may affect different aspect of cell structure and function] under the effect of chronic lead toxicity and their modulation with vitamin E. For this purpose forty two male new-Zealand rabbits of 2-3 months old, average body weight 2-3 kg were randomly divided into three equal groups, each of 14 animals. The first group [GI] kept as control. The second group [G II] received orally lead acetate [l/20 of L.D.50] daily for 90 days. The third group [G III] administrated orally [lead acetate + vitamin E] daily for 90 days. Heparinized blood samples were obtained from all groups, plasma was separated and used for determination of lipid peroxidation [L. malondialdehyde]. Red blood cells were processed for determination of cholesterol, phospholipids and fatty acid composition in erythrocytes membrane. Our data revealed significant increase in plasma MDA level [P < 0.001] and erythrocyte membrane cholesterol [P < 0.05] in lead intoxicated group, which decreased after vitamine E treatment. Whereas a significant decrease in membrane phospholipids [P < 0.05] and alteration in fatty acid pattern which also modulated by vitamin E supplementation

The differential effect of liposomal amphotericin B on human erythrocytes and promastigotes of Leishmania sp / Efecto diferencial de la anfotericina B ligada a liposomas sobre eritrocitos humanos y promastigotes de Leishmania sp

In this work, it was studied the effect that amphotericin B bound to liposomes (L-AmB) exerted on the potassium permeability of human erythrocytes and also on the rate of growth on culture of promastigotes of Leishmania sp. Liposomal amphotericin B was prepared by adding AmB to sonicated liposomes composed of egg-phosphatidylcholine (PC) or dipalmitoyl-phosphatidylcholine (DPPC). Incubation of human erythrocytes with free AmB (dissolved in organic solvent) led to a rapid enhancement of potassium efflux from erythrocytes. This permeabilizing effect of amphotericin B in erythrocytes decreased when the polyene antibiotic was added dissolved in a salt solution but it was negligible when AmB was added bound to liposomes (L-AmB). Liposomal AmB preparations made of PC or DPPC were equally effective in reducing AmB -induced potassium efflux from red cells to a minimum. By contrast, it was found that exposure of Leishmania promastigotes to liposomal AmB (PC or DPPC L-AmB) led to an inhibition of cell growth rate in a magnitude comparable to that exerted by AmB added in salt solution. Short term measurements of the magnitude of cell lysis after treating Leishmania promastigotes with amphotericin B revealed that the lytic effect of AmB added in aqueous solution, organic solvent or as PC-Liposomal AmB can be detected much earlier than that exerted by DPPC-Liposomal AmB. These results are discussed in terms of the differential capacity of AmB binding to liposomes of different composition and also on the characteristics of the mechanism of incorporation of AmB molecules to the membrane of target cells