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Biomedical subjects

O Morin

Publications and source records attributed to O Morin.

At least 55 records · Page 3Linked to original sources
PubMed1982

Insulin and glucagon binding and stimulation of amino acid transport in isolated hepatocytes from streptozotocin diabetic rats.

The binding of insulin and glucagon and the effects of these hormones on amino acid transport were examined in isolated rat hepatocytes from streptozotocin diabetic rats. Hepatocytes from diabetic rats bound more insulin than cells from control animals. These changes were accounted for by a 50%-60% increase in the number of insulin receptors per cell. Glucagon binding did not significantly differ in hepatocytes from both groups. Following a 2 hr incubation of the cells in vitro, the basal rate of alpha-aminoisobutyric acid (AIB) influx was enhanced in diabetic rat hepatocytes compared to controls. This alteration was accounted for by an increase in the Vmax of both a low affinity and a high affinity component of transport. The ability of diabetic rat hepatocytes to respond to maximally stimulating concentrations of insulin or glucagon by enhancing further the rate of AIB influx was markedly diminished. Hormone responsiveness was restored to normal in hepatocytes from insulin-treated diabetic animals. The data suggest that in diabetic rat hepatocytes the diminished insulin and glucagon responsiveness with regard to the stimulation of amino acid transport stems from postreceptor alteration(s).

Aminoisobutyric Acids↗
PubMed1982

Binding and action of insulin and glucagon in monolayer cultures and fresh suspensions of rat hepatocytes.

Insulin and glucagon binding, and the subsequent stimulation of amino-acid transport, were investigated in adult-rat hepatocytes. Cells were used either in suspension shortly after isolation, or as monolayers after 20 h of culture in a serum-free medium. At 37 degrees C, hepatocytes in monolayer cultures bound 2.5 times as much insulin and glucagon as did freshly isolated cells, owing to an increase in the total number of binding sites per cell. For both hormones, these differences could be accounted for mainly by a greater number of low-affinity binding sites in primary cultured hepatocytes compared with freshly isolated cells. Exposure of hepatocytes to insulin or glucagon for 2-3 h at 37 degrees C in a medium free from amino acids increased the capacity (primary cultures) or induced the emergence (fresh suspensions) of a similar high-affinity component (Km approximately mM) of alpha-aminoisobutyric-acid (AIB) transport. Primary cultured hepatocytes were more sensitive to insulin (half-maximal effect occurred with insulin at approximately 0.3 nM) than freshly isolated cells (half-maximal effect approximately 0.7 nM) for the stimulation of AIB transport, whereas the dose-response curves were virtually indistinguishable for the glucagon stimulation of AIB transport in both preparations of cells (half-maximal effect occurred with glucagon at approximately 1.5 nM). These results indicate that, despite differences in the apparent insulin- and glucagon-binding capacities (which involved mainly a low affinity site), both freshly isolated and primary cultured (20-h monolayers) hepatocytes behave similarly in response to insulin and glucagon with regard to the stimulation of amino acid transport.

Amino Acids↗
PubMed1981

[Possible transfer between sarcomatous mouse cells (BP8) and yeasts (Saccharomyces cerevisiae, whole bodies and protoplasts)].

From our observation in vitro, we can suggest that : a direct contact between sarcomatous cells and physiologically active yeasts appears to be necessary for the transfer of the radioactive labelling; the presence of a filter with pores of 1.2 micrometer diameter prevents passage of fragments of DNA or RNA between the cells; this transfer is a very small fact, but implies about the third of the yeasts.

Animals↗
PubMed1980

[New approach to the study of the experimental inhibitory effect of the unicellular alga Chlorella pyrenoidosa against the murine sarcomas BP8 and L1210].

In this paper, the authors are relating the inhibitory effect of the unicellular alga Chlorella (Beijerinck, 1890) pyrenoidosa Zeitler and Lund, against the tumoural rodent strains BP8 and L1210, according to the amount of inoculum. The statistical study of the results allows to the conclusive fact of a real protective effect showed by this microorganism and of a demonstrative relation between the amount of the protective material and the tumoural answers the high amount giving a better inhibitory effect. The workers also insist on the lack of pathogenicity presented by the alga used in this study.

Animals↗
PubMed1978

Modulation of antibody synthesis by an anti-tumour alga.

An unicellular alga, Chlorella pyrenoidosa, which had been reported to protect C3H mice against sarcoma BP8, is shown, when injected in Freund's incomplete adjuvant, to modulate the antibody synthesis induced by immunization with a hapten-carrier complex. C. pyrenoidosa appeared to be able to initiate an antigenic competition between hapten and carrier determinants of the antigen molecule during antibody synthesis, and thus it could be speculated that C. pyrenoidosa modulates the immune response at the macrophage level.

Anaphylaxis↗
PubMed1977

[New scanning electron microscopy contribution to the study of yeast protoplasts].

Study by scanning electron microscopy enables us to describe with precision the morphology of protoplasts. We can confirm that the wrinkles more or less perceptible on the protoplasts studied, do belong to the morphology of those just mentioned, that the presence or the absence of globulous component is connected with the physiological activity of the cell and that it is possible to distinguish the different protoplasts thanks to their morphological aspect.

Candida↗
PubMed1977

[Autoradiography of the exchanges that can occur between murine sarcoma cells (BP 8) and yeast cells (Saccharomyces cerevisiae, complete or protoplast)].

We can tell after observing the resulting negative that yeasts are able, in our experimental conditions, to collect a sequence of ADN and of ARN proceeding from the cancerous cells. Then, those yeasts could turn their synthesis towards the production of new materials. If those informed yeasts were introduced into a mouse, they would induce at the level of the immunocompetent cells a specific immunizing antitumoral power.

Animals↗
PubMed1976

Binding of the opiate-like pentapeptide methionine-enkephalin to a particulate fraction from rat brain.

The characteristics of stereospecific binding of [3H] met-enkephalin (15 Ci/mmole) were studied in a particulate fraction from rat brain. The binding assay was performed for 70 min at degrees C and the bound radioactivity separated by filtration through glass fiber filters (Whatman, GF/C). In the absence of sodium, binding of [3H] met-enkephalin could be described on the basis of two independent binding sites with apparent KDs of 2.1 and 53 nM, respectively. The data are also consistent with one class of binding sites showing negative cooperativity. In the presence of 100 mM NaCl, binding of [3H] met-enkephalin was 90-95% reduced, thus indicating the agonist properties of the peptide. The highly stereospecific binding of [3H] met-enkephalin was evidenced by the 10,000-fold greater potency of levorphanol than its analgesically inactive enantiomer dextrorphan to compete for [3H] met-enkephalin binding. Similar conclusions could be reached using levallorphan, (+)-3-hydro-N-allyl-morphinan, (-) methadone and (+) methadone. The apparent affinity of various opiate agonists and antagonists for the binding sites was closely correlated with their known pharmacological activity.

Animals↗
PubMed1976

[Experimental role of the unicellular algae Prototheca and Chlorella (Chlorellaceae) in anti-cancer immunogenesis (murine BP8 sarcoma)].

Bacteria and Yeasts are able to induce, when inoculated into laboratory rodents, a general stimulation of defences by an immune process. We could estimate that unicellular algae would induce the same phenomenon because the chemical compounds of their walls are related to those of the precedings microorganisms specially to bacteria. Indeed, two Chlorellaceae, Prototheca segbwema and Chlorella pyrenoidosa are respectively protecting 78% and 82% CH3 mice against the sarcoma BP8 grafting.

Animals↗