Vera C. O. Carvalho

Alterações nos níveis de colesterol, triglicerídeo e fosfolipídeo total em plasma de Callithrix jacchus (sagüi) reinfectado por Schistosoma mansoni

Little information is available on the lipid changes caused by Schistosoma mansoni reinfection. In this work it was evaluated alteration in the plasma lipids due to one reinfection by Schistosoma mansoni in the non human primate Callithrix jacchus (sagüi). Blood samples from C. jacchus, prior and after 60 days infection and reinfection, were collected by intravenous puncture, anticoagulated with EDTA (1mg/mL) and centrifuged at 2,500 xg, in order to obtain the plasma. Total cholesterol, cholesteryl ester, total phospholipid and triglyceride levels were determined by spectrophotometer methods. The results showed that there are significant reduction in cholesterol total, cholesteryl ester, total phospholipid and triglyceride concentrations in plasma of animals reinfected by Schistosoma mansoni, in comparison to the same animals prior and after one infection. This study showed that a second infection of Callithrix jacchus by Schistosoma mansoni causes plasma lipid alterations, which are more significant than after a single infection.

Efeito de tratamento cirúrgico sobre a atividade da enzima hepática lecitina: colesterol aciltransferase (LCAT) na esquistossomose mansônica

Schistosomiasis mansoni is a tropical disease and remains as an important public healthy problem in Northeast - Brazil, where it is highly endemic. This disease has the liver as the major focus of its histological lesions, physiopathological alterations and clinical manifestations. Previous studies have shown alteration on lipid metabolism in the hepatosplenic form of Schistosomiasis. One of the main alterations is the reduction on lecithin: cholesterol acyltransferase (LCAT) activity, an hepatic enzyme that catalyze the esterification of cholesterol in plasma In this work, we evaluate the LCAT activity in plasma from patients with hepatosplenic Schistosomiasis mansoni who were subjected to a new surgical treatment, which consists of splenectomy followed by auto-transplantation of spleen tissue. LCAT activity was detected by using a radioactive substrate. Both [14C]free and esterified cholesterol produced by the LCAT reaction were separated by thin layer chromatography, and the sample radioactivity was counted in a liquid scintilation analyzer. LCAT activity from plasma of patients subjected to splenectomy and spleen tissue implantation were reduced by 32 %, in comparison to the control group. However, in Schistosoma mansoni patients who were only clinically treated the reduction on LCAT activity was twice (64%) as much as that found in plasma of patients subjected to splenectomy and spleen tissue implantation. These results suggest a significant improvement on LCAT activity after the surgical treatment of patients with the hepatosplenic form of Schistosomiasis mansoni.

Schistosoma mansoni: A comparative study of plasma and erythrocyte lipid alterations in the experimentally infected mouse and in selected human patients

Abstract Alterations of plasma and erythrocyte lipids associated with hepatosplenic schistosomiasis mansoni were studied in the mouse and in human patients. Qualitative and quantitative differences were observed between the two species which indicated that the experimentally infected mouse should not be used as a model for altered lipid metabolism associated with Schistosoma mansoni infections in man. Also blood lipid values should not be used as prophylactic indicators for experimental therapeutical studies in the infected mouse, although lipid determinations could have clinical value in studies of human patients. In infected mice plasma cholesterol and phospholipid were significantly reduced (40 and 25%, respectively), but proportions of individual plasma phospholipids were unchanged. In contrast, only plasma cholesterol was reduced in human patients with compensated or decompensated hepatosplenic schistosomiasis (16 and 29%, respectively); of the individual phospholipids, lecithin was significantly increased and lysolecithin was decreased. The percentage of plasma total cholesterol was reduced in infected mice and patients suggesting that hypocholesterolemia is due mainly to decreased cholesteryl ester. Lipid changes also occurred in erythrocytes. Those of infected mice had significantly elevated membrane phospholipid content and no changes in cholesterol or in the proportions of the individual phospholipid fractions. In marked contrast, the erythrocytes of two groups of human patients had significantly higher levels of cholesterol without a raised total phospholipid concentration. Moreover, decreased proportions of lysolecithin and increased proportions of lecithin were apparent although only the increased membrane lecithin associated with compensated patients was statistically significant.

Lipid composition of erythrocytes from reptiles and amphibians

Abstract 1. 1. The concentrations of cholesterol and phospholipids in erythrocytes from seven species of reptiles and two species of amphibians were compared with the lipid composition of human and mouse erythrocytes. 2. 2. The phospholipid composition of reptile and amphibian erythrocytes were all remarkably similar whereas large differences occur between mammalian species. 3. 3. Erythrocyte cholesterol/phospholipid ratio was much lower for reptiles and amphibians than for mammals.

A comparative study of lecithin:cholesterol acyltransfer in plasma of five species of amphibians from Northeast Brazil

Abstract 1. 1. Lecithin:cholesterol acyltransfer (LCAT) was studied radiochemically in plasma from five species of Salienta, Bufo paracnemis, B. granulosus, Rana palmipes, Hyla raniceps and Leptodactylus ocellatus. 2. 2. Large inter- and intra-species variations in plasma LCAT activity were observed but activity correlated significantly with plasma triglyceride concentrations. 3. 3. The effects of pH and inhibitors on LCAT activity in amphibian plasma were similar to those described for mammalian plasma. 4. 4. Storage at −15°C for several weeks reduced LCAT activity in amphibian plasma but not in human plasma. 5. 5. Cholesteryl esters synthesised by LCAT were predominantly monoenoic in plasma of Bufo species and polyenoic in plasma of other species.

Influence of hypoxanthine and other purines on the lecithin:cholesterol acyltransferase reaction in the plasma of rat and other species

1. Esterification of radiolabelled cholesterol in the plasma of rat, mouse, pig, ox and, to a lesser extent, guinea pig was partially inhibited by hypoxanthine, xanthine and guanine; esterification in human plasma and in plasma from 12 other vertebrate species was unaffected by purines. 2. Esterification of endogenous cholesterol and the formation of lysolecithin in rat plasma were decreased in the presence of purines indicating that it was the lecithin:cholesterol acyltransferase (LCAT) reaction that was inhibited rather than the isotopic equilibration of labelled cholesterol with the endogenous substrate lipoproteins. 3. Maximum inhibition of the LCAT reaction in rat plasma occurred at 1.4 mM hypoxanthine or xanthine; inhibition was not dependent upon the concentration of LCAT or plasma lipoproteins but increased with the amount of lipoprotein depleted rat plasma (LDRP) present in the incubation mixture. 4. Partial inhibition of the LCAT reaction in rat or mouse plasma by purines had no significant effect on the fatty acyl composition of the cholesteryl esters (CE) formed by LCAT. 5. In the presence of heated rat plasma, LDRP or, to a lesser extent, rat high density lipoproteins (HDL) prepared from heated plasma, the LCAT reaction in human plasma was inhibited by hypoxanthine. 6. Rat HDL and LDRP prepared from plasma pre-incubated at 37 degrees C for 4 hr before heating increased and decreased, respectively, the inhibitory effect of hypoxanthine on human plasma LCAT compared with HDL and LDRP prepared from unincubated rat plasma.(ABSTRACT TRUNCATED AT 250 WORDS)