PubMed Health⌕ Search

Biomedical subjects

B Chataing

Publications and source records attributed to B Chataing.

At least 19 recordsLinked to original sources
PubMed1999

Purification and properties of phosphoglucose isomerases of Trypanosoma cruzi.

Glucosephosphate isomerase (PGI; EC 5.3.1.9) of Trypanosoma cruzi epimastigotes was found in about the same proportion in the glycosome and the cytosol. This subcellular distribution is similar to that of Leishmania mexicana, but contrasts with that of T. brucei bloodstream form, where the enzyme is essentially restricted to the glycosome. Glucosephosphate isomerase was highly purified from a glycosome-enriched fraction and to about 70% purity from the soluble extract. Both enzymes displayed Michaelis-Menten-Henri kinetics. Km values for fructose 6-phosphate were 0.125 +/- 0.07 and 0.80 +/- 0.10 mM for the glycosomal and the cytosolic PGIs, respectively. Erythrose-4-phosphate, 6-phosphogluconate and mannose-6-phosphate were inhibitors for both PGIs. Phosphogluconate and erythrose phosphate showed higher affinity for cytosolic PGI than for glycosomal PGI, by 2.5- and 4-fold respectively. The PGIs differed slightly in their isoelectric point (7.1 +/- 0.15 and 7.5 +/- 0.12) and optimum pH range. Both PGIs also differed in their chromatographic properties (ion-exchange and phenyl Sepharose), indicating a difference in charge and hydrophobicity, with the glycosomal enzyme being more hydrophobic. The molecular mass of both PGIs was 186,000 +/- 9000 Da, which is higher than that of other known PGIs, including those from T. brucei and other trypanosomatids. The molecular mass of the subunit, 63 kDa, is similar to that of PGIs from other sources. It appears that PGIs from T. cruzi are trimeric, in contrast with all other known PGIs which are dimeric.

Animals↗
PubMed1998

Inhibition of Trypanosoma cruzi growth in vitro by Solanum alkaloids: a comparison with ketoconazole.

The glycoalkaloids alpha-chaconine, alpha-solamargine, alpha-solanine, solasonine, sycophantine, and tomatine, as well as the aglycones demissidine, solanidine, solanocapsine, solasodine, tomatidine, and veratrine were tested as growth inhibitors of Trypanosoma cruzi, strain EP, in LIT medium. Their activity was compared with the antifungal ketoconazole. Glycoalkaloids containing alpha-chacotriose showed trypanolytic activity against the epimastigote form and trypanocidal activity against the bloodstream and metacyclic trypomastigote form of Trypanosoma cruzi in culture medium in micromolar concentrations. Ketoconazole showed a lower activity, at the same concentrations of alpha-chaconine and alpha-solamargine. The observations indicate that the initial target of the compound is at the membrane level with a concomitant change in the parasite morphology. Moreover, internal compartments of the parasites were observed to be affected by the drugs, revealing the dissolution of some organelles as mitocondrias and glycosomes.

Alkaloids↗
PubMed1990

[Transfusion of concentrates enriched in neocytes in the thalassemic child. Preliminary results].

In this study, we compared the results of young red cells transfusion for 12 months with the administration of conventional red cells units during the year before, in three thalassemic children. We used the Neocel system (Cutter laboratories) to prepare neocytes. A quality control of neocyte units was developed: especially the phthalate oil technique which shows a 70% enrichment of young red cells. These patients received 170.4 +/- 9 ml/kg of body weight of neocytes compared with 197 +/- 20 ml/kg of body weight of conventional red cells concentrates. The mean decrease of hemoglobin transfused per kg of body weight per year was 22%. The mean pretransfusion hemoglobin level did not change during the 2 years of study. The children grow without any problem and no pathologic event occurred during the study. The control of the serological ferritin levels does not allow for definitive conclusions in the evolution of the iron overload of our three patients. However, this overload seems to decrease. It's why it's necessary to carry on with our study.

Blood Transfusion↗
PubMed1985

[Limulus test using a chromogenic method: application to the control of pyrogens in blood derivatives].

We report here the application of the LAL Test to a chromogenic substrate to detect endotoxins in Human Blood Products. In order to reduce the cost, we used a microplate procedure with the Multiskan Reader. Quantitative results in the range of 0,01 to 0,1 ng/ml allowed for a good correlation with the Rabbit Pyrogen test. For 20% albumins and 4% albumins, the mean endotoxins levels of non pyrogenic lots were 0,38 +/- 0,18 and 0,09 +/- 0,03 ng/ml. All the lots which passed the Rabbit Pyrogen test had endotoxins levels lower than 1 ng/ml and 0,2 ng/ml, respectively. We can use this test for other plasma derivatives; Gammaglobulines and PPSB are easily tested. Dried Concentrated Antihemophilic Factor and Dried plasma contain citrate which inhibits the reaction. Dilution and Addition of Calcium Chloride overcome this inhibition. For dried plasma, we should destroy plasma inhibitors by heating at 75 degrees C. This sensitive and reproductible in vitro assay improves the control of pyrogenecity in Human Blood Products.

Blood Transfusion↗
PubMed1982

Plasma protein-facilitated coupled exchange of phosphatidylcholine and cholesteryl ester in the absence of cholesterol esterification.

A protein(s) which catalyzes the exchange of phosphatidylcholine and cholesteryl ester between plasma lipoproteins has been purified 10,000-fold from lipoprotein-free human plasma. The apparent molecular weight of the protein of the active fraction, designated lipid transfer complex (LTC), is approximately 61,000; when electrophoresed in 6 M urea, 0.1% sodium dodecyl sulfate on a 3-20% polyacrylamide gradient, the protein appears as a doublet of molecular weights 58,000 and 63,000. The active material is a glycoprotein which binds to concanavalin A. Human LTC is a lipid-protein complex with phospholipid, cholesterol, cholesteryl ester, and glyceride comprising 7% of the total mass. A similar glycoprotein (or glycoproteins) exists in rat plasma, although the fold-purification thus far achieved is low: about 500-fold. Moreover, the rat preparation enhances exchange of phosphatidylcholine, but does not appreciably enhance exchange of cholesteryl ester. Partially purified LTC (less than or equal to 3500-fold) exists in a complex with lecithin: cholesterol acyltransferase. Active lecithin: cholesterol acyltransferase is not, however, required for exchange of phosphatidylcholine or cholesteryl ester facilitated by human LTC. The rates of exchange of phosphatidylcholine and cholesteryl ester facilitated by human LTC are equal. Coupled lipid exchange occurs at all stages of LTC purification, at values of pH between 5 and 10, and at ionic strengths as great as 0.9. Moreover, phosphatidylcholine and cholesteryl ester are exchanged with 1:1 stoichiometry in the presence of thiol group reagents such as 5,5'-dithiobis-(2-nitrobenzoic acid). Both lipid exchange activities are relatively resistant to elevated temperatures. Coupled exchange of phospholipid and neutral lipid is not dictated by the nature of the lipoprotein donor and acceptor substrates: bovine liver phospholipid exchange protein catalyzes exchange of phosphatidylcholine but not cholesteryl ester between low and high density lipoproteins under conditions identical with those in which human LTC facilitates exchange of both lipids.

Animals↗
PubMed1982

Kinetics of plasma protein-catalyzed exchange of phosphatidylcholine and cholesteryl ester between plasma lipoproteins.

A lipid transfer complex (LTC) isolated from human plasma catalyzes equimolar exchange of cholesteryl ester and phosphatidylcholine between low density (LDL) and high density (HDL) plasma lipoproteins. Activation parameters for LTC-catalyzed exchange of neutral and polar lipid are equal and are not influenced by the degree of purity of the catalyst. Activation parameters for exchange of both cholesteryl ester and phosphatidylcholine are influenced by the extent of saturation of phosphatidylcholine fatty acyl groups. The activation parameters also depend on the amount of HDL present in the assay. The flux rates of lipid exchange depend on the concentration of both LDL and HDL. At constant HDL concentration, flux rates become independent of LDL concentration when the ratio of [LDL]:[HDL] exceeds 9:1 (based on cholesteryl ester); at constant LDL concentration, facilitated LDL,HDL lipid exchange is inhibited at high HDL concentration, suggesting preferential HDL,HDL exchange. Analysis of the dependence of initial lipid exchange rate on LDL concentration at two constant HDL concentrations suggests that, in the reaction pathway, LTC mediates a productive collision (ternary complex) between LDL and HDL. A kinetic mechanism consistent with the data is one in which lipid exchange occurs in a ternary complex consisting of LTC, HDL and LDL. At low HDL concentration, this complex is formed by a random sequential route; at high HDL concentration, the mechanism is ordered sequential since the reactants are an LTC-HDL complex and LDL.

Carrier Proteins↗
PubMed1978

[Incidence of monoclonal gammopathies in blood donors].

A routine screening of monoclonal gammopathies (M.G.) was performed in the serum from 36, 015 blood donors by cellulose acetate electrophoresis. The incidence of M.G. was estimated to 0.14 per cent. About 86 per cent of cases can be classified as asymptomatic M.G. and 14 per cent as malignant M.G. (myeloma or Waldenström macroglobulinemia). In asymptomatic forms, heavy chain classes are only IgG or IgM with a large predominance of IgG (86,4%). It is suggested that donors in whom M.G. have been detected should not be allowed to give blood. A yearly clinical, hematological and an immunoglobulin check-up is recommended to these patients in order to defect the first sign of a malignant process.

Adult↗
PubMed1976

[Changes in the erythrocyte membrane during blood preservation. Influence of progesterone].

Modifications of the erythrocyte membrane during blood conservation are studied. The functional condition of the membrane was observed by means of the biosynthesis of lecithines; modifications occurring at the level of the composition of the membrane proteins were then looked for. The study has been carried out on fresh blood and on blood stroed for 8 days, 15 days, 29 days and 43 days. Another series of assays has been done on stored blood in the presence of progesterone after the same conservation periods. The metabolic activity of the membrane, in the lecithine biosynthesis is studied by measuring the incorporation of fatty acid in the lysolecithines when the membrane is incubated in the presence of linoleic acid or [14] palmitic acid and coenzyme A, or in the presence of [14C] palmitoyl coenzyme A. Variations have been observed during blood conservation: the incorporation or radioactive fatty acid increases during the first 15 days of conservation, then it decreases to a value nearing the original value after 43 days. When the blood is stored in the presence of progesterone (1,6 mumole/1) a more stable incorporation of the fatty acid is observed; variations during conservation are weaker than without progesterone. Membrane proteins have been studied by electrophoresis on polyacrylamide gel after solubilisation by sodium dodecyl sulfate. The intensity of protein zones after coloring, decreases during conservation especially in proteins with a high molecular weight. A quantitative study has been made by chromatography on Sephadex G200 of dansylated proteins with a fluorimetric dosage. In the presence of progesterone, the decrease of the rate of proteins with a high molecular weight is weaker. Therefore, progesterone is proved to allow a better conservation of erythrocyte membrane proteins. As a conclurion, the results of these works show a positive action of progesterone on the erythrocyte membrane during blood conservation.

Blood Preservation↗
PubMed1976

[Clinical symptoms of transfusional malaria].

Tranfusional malaria in countries located outside zones of endemia is difficult to evidence because it is rarely aparent. The clinic can be compared to that of malaria through inoculation by anophele, but it can be difficult to evidence because of its intricacy with the symptomatology of the affection which justified the transfusion. Usually, it takes the appearance of a febril gastric problem, but it may have other aspects: intestinal, hepato-biliar, neurologic or hematologic symptoms. As soon as the diagnosis is established, it is easy to confirm by a cytologic test on peripheric blood and/or on bone marrow and specially by a sero diagnosis using immuno fluorescence.

Biliary Tract Diseases↗
PubMed1976

[Methods of sampling and preservation of blood used during extracorporeal circulation].

The blood supply of Cardiac Surgery Centers set quantitative and qualitative problems to the Centers of blood dispatch. In this work, from a Lyonese experience on 4,000 E.C.C., authors try to define the best preservative solution, especially for the respiratory function of the red blood cell. The C.P.D. solution (citrate, phosphate, dextrose) answers to requirements in this field when the blood used is less than 48 hours old. In the meantime, it is not impossible that studies based on definite criteriums of evaluation and on severe comparisons allows to adapt new process from which some are described and criticized in this work.

Blood Preservation↗