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Biomedical subjects

C Lacombe

Publications and source records attributed to C Lacombe.

At least 199 records · Page 11Linked to original sources
PubMed1978

[Demonstration of erythroblastic differentiation after 14 days in blood in vitro during Vaquez's disease without addition of erythropoietin].

Leucocytes of normal individuals and patients with polycythemia vera were isolated from the peripheral blood by Ficoll-Hipaque density gradient centrifugation and cultured in vitro suing the bovine plasma clot culture technique with a minor modification: the addition of fresh normal serum. After 14 days in the presence of sheep erythropoïetin (3U/ml) erythropoïetic bursts containing between 3 and 10 subcolonies were observed in normal and polycythemia vera cultures. Blood leucocytes of patients with polycythemia vera rise to these erythropoïetic bursts without addition of erythropoïetin to the culture. This behavior was never observed in the blood of normal individuals. These results indicate that in polycythemia vera commited erythroïd stem cells of high proliferative capacity closely resembling the murine erythroïd burst forming unit have an abnormal sensitivity to erythropoïetin as well as the immediate precursors of the proerythroblasts. The culture of these cells from the peripheral blood offers some practical advantages.

Cell Differentiation↗
PubMed1978

[Comparative study of effects of tannic acid and oxidized tannic acid on growth, body composition and biological utilization of nutriments in rats].

The nutritional effects of oxidized tannic acid in rats have been compared with the effects of tannic acid supplemented or not with a reductor: sodium sulfite. The results indicate that in the group which ingested oxidized tannic acid, fecal nitrogen excretion is lower than in the group which ingested tannic acid; its action on growth is mainly exerted by reduction of the retention coefficient; urinary nitrogen excretion being increased. With regard to the other groups of animals, oxidized tannic acid decreases the weight gain of the thymus and slightly increases the weight gain of the heart. Sulfite supplementation does not change the effects of tannic acid on growth; nevertheless, a higher weight gain of the kidneys is noted.

Animal Nutritional Physiological Phenomena↗
PubMed1978

[In vitro study of erythroid precursors in Vaquez' disease (polycythemia vera). Evidence supporting 2 populations of erythroid 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 dose 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 independent 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. In 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.

Cell Differentiation↗
PubMed1977

[Abnormal sensitivity to erythropoietin in the erythroblast precursors in Vaquez disease].

Marrow specimens of patients with polycythemia vera rise to erythrocytic colonies in vitro without addition of erythropoietin to the culture. This behavior was never observed with marrow cells of normal subjects or secondary erythrocytosis. These results indicate that the sensitivity of some erythrocytic progenitor cells to erythropoietin is altered in polycythemia vera.

Bone Marrow↗
PubMed1977

Tannic acid and oxidized tannic acid on the functional state of rat intestinal epithelium.

Diets containing tannic acid at the level of 3% of dry matter were fed to rats in order to ascertain the origin of fecal nitrogen and the effect of tannic acid on the intestinal mucosa. At the same time in order to explain the effect of oxidation of tannins, we administered diets containing oxidized tannic acid or tannic acid associated with an antioxidizer (sodium sulfite) at the level of 1% of dry matter. The increased excretion of sialic acid and glucosamine during ingestion of tannic acid indicated that the excess of fecal nitrogen mainly corresponds to the mucus hypersecretion observed by histology. Fecal analysis revealed perturbations in movements of water and ions. The study of the metabolic activity of isolated enterocytes and the activity of some enzymes in a homogenate of these cells showed an inhibition of oxygen consumption and succinic dehydrogenase activity. Addition of reducing agent (sodium sulfite) to the diet had little effect on the action of tannic acid; but previous oxidation of the tannin reduced the effects observed, particularly in the case of fecal nitrogen loss.

Animals↗
PubMed1977

A circular dichroism study of DNA-basic peptides associations in the absence or in the presence of Ca++.

The interaction of DNA with basic peptides (Lys methyl ester*, Lys2, (Lys)2methyl ester) has been studied by circular dichroism. The changes of the DNA CD spectra in the presence of peptides are interpreted as a transconformation from the B form to the C form of DNA. The presence of Ca++ in the mixture induces a supplementary transconformation. These observations suggest Ca++-basic peptides-DNA complexes as a structural model for chromatin.

Animals↗
PubMed1977

[Characterization of the membrane attached to the folded chromosome isolated from Escherichia coli].

Phospholipid analysis of the membranes associated with fast sedimenting folded chromosomes prepared by lysis of E. coli CR 34 shows that both inner and outer membranes are parts of the complex, in proportions not very different from that found in the whole bacteria. During the preparation of the folded chromosomes, the most recently synthesized molecules of phosphatidylglycerol and phosphatidylethanoamine are more sensitive to solubilisation, particularly those from the cytoplasmic membrane. Identification of a dominant fraction, the outer membrane, in some complexes, results from a preferential solubilization of the inner membrane. These results do not favor any specific association between the folded chromosome and the membranes.

Cell Fractionation↗
PubMedDate not supplied

[Toxicokinetics of a thioquinoxaline component: the oxythioquinox (author's transl)].

The absorption and distribution of Morestan 35S in the organism of the rat were studied after administration by stomach tube. It was shown that Morestan, in vivo and in vitro, forms a complex with plasma proteins and particularly with albumins. Most of the plasma Morestan is distributed like this. After intravenous admininstration, the constant of elimination, K13, and the biological half-life determination show that plasma Morestan 35S is eliminated very slowly. The K12 and K21 constants indicate that there is an equilibrium between the plasma compartment and a peripheral compartment. After intragastric administration, the increase of radioactivity in epididymal adipose tissue, indicate that the peripheral compartment should include the adipose tissue.

Administration, Oral↗
PubMedDate not supplied

Relevance of measuring red blood cell disaggregability in insulin-dependent diabetic patients.

A viscometric study of blood from insulin-treated diabetic patients is carried out. Patients are divided into three major groups--group I: without or with minimal retinopathy and recent diabetes (n = 37), group II: without or with minimal retinopathy and at least 20 years of diabetes duration (n = 35), group III: with severe retinopathy (n = 27). Each group is also subdivided according to the glycosylated hemoglobin (HbA1c) level, used to assess long-term glycemic control. Finally, the rheological parameters of six groups are compared: three of which have a HbA1c level less than 7.5% [I1 (n = 15), II1 (n = 9), III1 (n = 9)] and three others have a HbA1c level more than 7.5% [I2 (n = 22), II2 (n = 26), III2 (n = 18)]. The most important result concerns the thixotropy index xi t, which reflects the dynamic property of red blood cell (RBC) disaggregability under shear. Strong correlations between this parameter and HbA1c level are found for groups I (r = -0.53, p < 0.001) and III (r = -0.68, p < 0.001), providing evidence of a RBC disaggregability disorder for a poor glycemic control of diabetes. In contrast, such a correlation is not pointed out for the group II. As the value for xi t is not statistically different for groups II1 and II2 and is close to the normal value in both groups, the existence of a rheological protection against the retinopathy could be involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗