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Biomedical subjects

C Lacombe

Publications and source records attributed to C Lacombe.

At least 181 records · Page 10Linked to original sources
PubMed1983

Tentative application of the tangent simple system method to the study of the viscoelastic behaviour of blood.

The method of the tangent simple systems is applied to the study of the viscoelastic behaviour of human blood in unstationary flow for rectangular steps and triangular ramps of shear rate. The tangent systems we utilize, Maxwell liquids, enable us to determine, at every point of the rheograms, apparent instantaneous values of retardation or relaxation time, viscosity coefficient and elasticity modulus of the studied blood samples, and to plot the curves of variation of these parameters as a function of flow duration. A qualitative interpretation of the results is proposed from data on the aggregation-disaggregation kinetics of red blood cells. Examples are given for samples of normal and pathological bloods.

Biomechanical Phenomena↗
PubMed1983

[The effect of insulin on hyperlipoproteinemia induced by a semi-synthetic diet rich in saturated fats in a rabbit].

The influence of insulin therapy on changes in the lipoprotein profile induced by a semi-synthetic saturated-fat diet was studied in the rabbit. Hypercholesterolemia, observed after two months diet, corresponded to an increase in all lipoprotein fractions as well as an enrichment in cholesterol esters of VLDL and LDL. Treatment with insulin had only a slight effect on the increase in the lipoproteins, but completely prevented the appearance of abnormal LDL. Changes in the lipoprotein profile were markedly aggravated, without an additional increase in plasma cholesterol, when the semi-synthetic diet was continued for six months. All lipoprotein fractions showed increases in cholesterol esters and in free cholesterol at the expense of triglycerides and proteins. The animals receiving the semi-synthetic diet and treated with insulin showed decreased glucose tolerance but no additional modifications in the lipoprotein profile or in the composition of aortic tissue. Therefore, insulin initially prevents alterations in LDL, induced by the semi-synthetic diet, prevention which is not maintained in the long term.

Animals↗
PubMed1983

[Production of an erythropoietic factor by mouse leukemia].

The graft of a transplantable leukemia (IW 32) induced by a biologically cloned helper of a Friend virus devoid of SFFV activity, was shown to induce a polycythemia in recipient animals. An in vitro continuous cell line was derived from this leukemia. The supernatant was shown to induce an erythroid differentiation both in vivo in Mice rendered polycythemic by transfusion, and in vitro in plasma clot CFUE assay. This erythropoietic activity was heat stable (30 min. 56 degrees C, 3 min. 100 degrees C) which ruled out the hypothesis that the IW 32 cell line produced a polycythemia inducing virus. The erythropoietic factor produced by IW 32 leukemic cells might be erythropoietin.

Animals↗
PubMed1983

Relationship between metabolism and composition of low density lipoproteins in rabbits on semi-purified diet.

The metabolism of 125I-labelled apoprotein of low density lipoproteins was studied in rabbits fed either commercial or semi-purified, cholesterol-free, diet. The rise in apo-LDL intravascular pool size observed in the semi-purified group is accompanied by a marked decrease in the fractional catabolic rate and an increase in the total catabolic rate. The semi-purified diet induces an increase in the cholesterol ester/triglyceride ratio of the LDL which is normalized by cholestyramine therapy. The concomitant alterations in both LDL metabolism and lipid composition raise the possibility that enrichment of LDL in cholesterol esters is a consequence of the delayed LDL clearance from the plasma.

Animals↗
PubMed1981

[Transient rheological study of blood stored in a liquid state].

The rheological properties of blood stored in different conditions (in liquid state or as globular concentrates in the presence of the classical anticoagulant ACD or CPD solutions, or according to the SAG procedure) have beenn studied with a Couette viscosimeter. Apparent viscosity was measured at very low shear stress (0.05 s-1) as a function of the storage time. Furthemore the dynamic rheological parameters (thixotropy, viscoelasticity and rheofluidification) were determined. Blood viscosity increases strongly as a function of storage time, particularly on whole blood. Its variation is weaker on globular concentrates, particularly with SAG. Thixotropy, viscoelasticity and rheofluidification, on the contrary, are not strongly perturbated. These rheological modifications are closely related with the changaes occuring in the morphology and in the aggregation state of the stored red blood cells.

Adult↗
PubMed1981

Erythroid progenitors in polycythemia vera.

Recent data concerning in vitro studies of erythroid progenitors in polycythemia vera (PV) are reviewed. As shown by different laboratories, at least two populations of CFUE seem to coexist in the bone marrow of such patients: one exhibits normal in vitro behavior; the other, probably of clonal origin, is abnormally sensitive to erythropoietin. This abnormal population of CFUE is highly sensitive to trace amounts of erythropoietin and is probably responsible for the in vivo development of polycythemia despite a depressed level of erythropoietin. At the BFUE level, two populations also seem to coexist. However, the abnormal behavior of erythroid progenitors is probably not expressed at this early level of differentiation but only at the late CFUE level. This is in agreement with some of the data, which suggest that in the differentiation of erythroid progenitors into erythroblasts, erythropoietin is only needed at a level very close to CFUE.

Animals↗
PubMed1980

Breed differences in nutritionally induced hyperlipoproteinemia in the rabbit.

The influence of a high-fat, cholesterol-free diet on the lipoprotein pattern is compared in New Zealand hyperresponder and Fauve de Bourgogne hyporesponder rabbits. Quantitative as well as qualitative differences were observed. The high-fat diet induces an increase in both LDL and HDL in the Fauve de Bourgogne, the ratio VLDL + LDL/HDL cholesterol being unchanged. By contrast, New Zealand rabbits present a greater increase in plasma cholesterol which is mainly transported by the VLDL and the LDL. Consequently the proportion of HDL cholesterol is markedly decreased. The breed difference in response to the diet is also noted in lipoproteins composition since only New Zealand rabbits show abnormal VLDL. These results are discussed in terms of differences in susceptibility to experimental atherosclerosis reported between the two strains.

Animals↗
PubMed1980

Lipoprotein modifications with changing dietary proteins in rabbits on a high fat diet.

Rabbits received a high-fat diet containing either casein or soya protein. Casein, in contrast to soya, enhanced the effect of the high-fat diet on the rise in plasma and liver cholesterol. The very low density lipoprotein (VLDL) and low density lipoprotein (LDL) of animals receiving casein showed an enrichment in cholesterol esters which coincided with a decrease in the triglyceride content. These cholesterol-rich beta lipoproteins may contribute to the potential atherogenicity of casein.

Animals↗
PubMed1979

[In vitro study of erythroblast precursors in Vasquez disease (polycythemia vera). Arguments in favor of a double population of erythroblastic stem cells in the bone marrow].

In vitro studies using the plasma clot culture system have been performed in order to compare the red cell pregenitors able to rise to erythrocytic colonies in 7 days (CFUE) in the bone marrow of polycythemia vera (PV), secondary polycythemias and normal subjects. In PV but never in normal individuals or secondary polycythemias, the bone marrow cells producing erythroid colonies without addition of erythropoietin were found. The erythropoietin dode response curves in PV is biphasic with a plateau up to a concentration of erythropoietin of 0.02-0.05 i.U./ml followed by a near normal response to erythropoietin at higher doses. Thus our results demonstrate that two populations of erythroid stem cells coexist in PV, one being abnormally sensitive to (or independant of) erythropoietin, the other normally responding to erythropoietin. After remission induced by P32 treatment, the abnormal population can disappear but the prognostic significance of this disappearance is uncertain. On the whole these results are in agreement with those of others laboratories using the plasma clot culture system. The reasons of the disagreement with the data published using the methylcellulose technic of culture are discussed.

Animals↗