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Biomedical subjects

M Leclerc

Publications and source records attributed to M Leclerc.

At least 73 records · Page 4Linked to original sources
PubMed1984

MLR-like reaction between axial organ cells from asterids.

The uptake of [3H]thymidine by axial organ (AO) cells arising from two starfishes and mixed together, in a ratio of 50/50 was studied. Mixed leucocyte reaction (MLR) combinations gave a positive response at the fifth day of culture in about 20% of the tested combination (index: 1.8-6.7). No positive reaction was observed in an allogeneic system. More significant results seem to be obtained with the nonadherent nylon-wool subpopulation cells from the two species, rather than with the whole axial organ cells.

Animals↗
PubMed1984

Fermentation of cellodextrins by different yeast strains.

The fermentation of cellodextrins by eight yeast species capable of fermenting cellobiose was monitored. Only two of these species, Torulopsis molischiana and T. wickerhamii, were able to ferment beta-glucosides with a degree of polymerization between one and six. These two species showed exocellular beta-glucosidase activity. Four other species were able to ferment cellotriose, and the last two species only fermented cellobiose. These latter six species produced a beta-glucosidase capable of attacking cellodextrins, but this enzyme was endocellular.

Journal Article↗
PubMed1984

Low molecular weight (LMW) heparin derivatives in experimental extra-corporeal circulation (ECC).

Low molecular weight (LMW) heparin has been shown to prevent experimental venous thrombosis. In order to investigate its biological action and its potential use in open heart surgery, we have conducted an experimental study using extracorporeal circulation (ECC) in sheep as an experimental model. 18 sheep were randomly selected to receive either LMW heparin (2 mg/kg), high dose heparin (HD; 160 U/kg), or low dose heparin (LD; 60 U/kg). The HD heparin yielded the same circulating anti-activated factor X (anti-Xa) activities as the LMW heparin and the LD heparin yielded the same anti-thrombin activity. LMW heparin and HD heparin were both effective in preventing blood clotting in the ECC circuit, demonstrating the antithrombotic activity of the LMW heparin. Clotting in the circuit was observed following LD heparin administration showing that the efficacy of LMW heparin does not only rely upon its weak anti-activated partial thromboplastin time (APTT) and anti-thrombin activity. Fibrinogen, fibrinogen degradation products (FDP), factor V (FV), platelet count, antithrombin III (AT III), fast acting antiplasmin (AP) were evaluated during and after ECC. The defects in hemostasis were similar in the three groups. Conclusions were: (1) heparin chain depolymerization diminishes the anti-APTT activity without altering the anti-thrombotic property; (2) LMW heparin is an effective alternative to heparin in cardiac surgery; (3) the absence of postoperative circulating anti-APTT activity might be associated with a reduced incidence of hemorrhagic complication, but we were not able to demonstrate it.

Animals↗
PubMed1983

Spontaneous and induced cytotoxicity of axial organ cells from Asterias rubens (Asterid--echinoderm).

Spontaneously occurring cytotoxicity of starfish axial organ cells on target cells has been studied. It appears that in an allogeneic system no cytotoxic phenomenon occurs after 4 or 6 h of culture, whereas spontaneous cytotoxicity toward malignant vertebrate target cells is shown and reaches its maximum at 37 degrees C. In a certain way, the axial organ cell population includes cells, which may be compared with vertebrate natural killer cells. On the other hand, it must also be noted that axial organ cells are able to exert in a few cases, an induced cytotoxicity on MBL2 cells. This phenomenon appears at the end of the fourth day of culture.

Animals↗
PubMed1983

Effect of in vivo inoculation of bacteria on the spontaneous cytotoxicity of axial organ cells from Asterias rubens.

In vivo inoculation of heat-killed bacteria in the coelomic cavity of starfish induces an increase of spontaneous cytotoxicity developed by axial organ (an ancestral lymphoid organ) cells, phenomenon demonstrated by an in vitro [51Cr]-release assay. This observation corroborates the existence of a sophisticated immune system in the echinoderms, a first-rate model for phylogenic study of the immune response.

Animals↗
PubMed1983

[Morphological aspect and chemical composition of Skeletonema costatum (Bacillariophyceae) growing in natural nutritive media with the aid of a culture system of dialysing fibers].

The growth of Skeletonema costatum, under natural nutriment conditions, was studied using a bulk culture fiber dialyzing apparatus. The diatom displayed normal development of chain length (average cell number per chain) which coincided with the culture growth stages; that is, the cell number per colony increased during the active division period and decreased thereafter with the beginning of the prestationary phase. This morphological behaviour showed that the alga cells were not affected by such physical shocks as collision or tension occurring during repeated cell transfers from growth chambers to the dialyzing apparatus or at the time of their passage through the fiber fascicles. Measured at different growth stages, the cell contents in carbon, nitrogen, and chlorophyll confirmed the above results and showed for S. costatum a biological productivity comparable with that obtained in smaller dialyzing containers (dialyzing bags). Through a comparison between the dialyzing culture and a static culture grown in an enriched medium, certain characteristics were determined.

Culture Media↗
PubMed1982

[Asymptomatic abetalipoproteinemia associated with partial apoprotein B deficiency: a familial case report].

The authors report a case of familial asymptomatic abetalipoproteinemia. The propositus has total abetalipoproteinemia associated with a partial apoprotein B defect. His two daughters have a subtotal betalipoprotein deficiency. This familial case, with autosomal dominant transmission, seems different from other reports. It supports the hypothesis that the primary involvement is a deficiency in apoprotein B synthesis, which appears more closely correlated with clinical symptoms.

Abetalipoproteinemia↗
PubMed1981

Properties of cell subpopulations of starfish axial organ: in vitro effect of pokeweed mitogen and evidence of lymphokine-like substances.

The in vitro effects of pokeweed mitogen (PWM) on axial organ (AO) cells of the echinoderm starfish Asteria rubens have been studied. PWM stimulates 3H-thymidine incorporation by the whole population of AO cells (index of stimulation 4-5). On the basis of surface adherence to nylon wool the AO cell population can be fractionated into adherent and non-adherent subpopulations. PWM strongly stimulates the non-adherent cells (index 14) but not the adherent cells (index 1.2-1.8). Specific soluble mediators obtained from stimulated non-adherent cells were able to stimulate the whole AO cell population but not the fractionated adherent or non-adherent cells.

Animals↗