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Biomedical subjects

P Lechat

Publications and source records attributed to P Lechat.

At least 199 records · Page 11Linked to original sources
PubMed1980

Influence of some irritating or immunostimulating substances on experimental pleurisy in the rat.

Irritating substances, such as turpentine, carrageenan and a reticulo-endothelial system-activating immunostimulant (crude cell walls of Mycobacterium smegmatis), when administered parenterally, inhibit various types of experimental pleurisies. These anti-inflammatory properties may be related to the increase which they induce in serum and pleural exudate levels of haptoglobin and of oxidative activity towards paraphenylenediamine.

Adjuvants, Immunologic↗
PubMed1979

Chronotropic effect of histamine on cultured neonatal rat heart cells.

The positive chronotropic effect (PCE) of histamine in cultured neonatal rat heart cells was monitored using a microscopic method as well as an electro-optically recording device. The action potential frequency was also measured (by means of microelectrodes). An increase in PCE was noted when histamine (from 1 X 10(-6) M to 1 X 10(-5) M) was added to the cells. However, higher concentrations (from 1 X 10(-5) M to 1 X 10(-4) M) were less effective. The PCE of histamine was reduced by pretreating the cells with antihistaminic drugs. H1-blocking agents (promethazine and mepyramine) were more potent than H2-blocking drugs (metiamide and cimetidine). In addition, the PCE of histamine was abolished when the cells were in presence of high K+ medium (26 mEq) but contraction and action potential amplitudes were increased. Our results demonstrate that these cultures respond to histamine and that this response is abolished by antihistaminic drugs thus suggesting the H1 and/or H2 receptors may be present in the neonatal rat heart cell cultures.

Animals↗
PubMed1979

Inhibitory effect of kanamycin on evoked transmitter release. Reversal by 3,4-diaminopyridine.

The effect of kanamycin (Kn) on evoked transmitter release was examined in frog end-plates in vitro. By a presynaptic action, Kn (0.02 to 1 mM) significantly reduced the amount of acetylcholine liberated by nerve stimulation. In addition to its presynaptic effects, Kn (0.96 mM) decreased the size of the miniature end-plate potentials possibly by acting at the postsynaptic level. 3,4-Diaminopyridine (4.5 microM) reversed the presynaptic effects of Kn but did not modify its postsynaptic action.

Aminopyridines↗
PubMed1979

[Reduction of isoprenaline induced tachycardia in pregnant rats. Role of a serum factor].

The in vivo isoprenaline (50 microgram/kg) induced tachycardia (beta 1 adrenergic stimulant effect) was decreased in pregnant (20th day) Rats compared to non pregnant Rats. The in vitro positive chronotropic effect of isoprenaline (10 ng/ml) on cultured Rat heart cells was abolished by pregnant Rat serum whereas progesterone (0.10 to 5 microgram/ml) or oestradiol (0.1 to 25 microgram/ml) were ineffective. The decreased beta 1 adrenergic responsiveness in pregnant Rats could be related to a seric factor, different from these two hormones.

Animals↗
PubMed1979

Analysis of the action of 4-aminopyridine during repetitive stimulation at the neuromuscular junction.

4-Aminopyridine (4-AP) increased the quantal content (m) of end-plate potentials (e.p.p.s) evoked by continual stimulation (0.2--25 Hz) in frog end-plates depressed by Mg2+. The increase in m was due to an increase in the binomial parameter n. This was interpreted to mean that 4-AP increased the number of activated release sites. In junctions blocked by d-tubocurarine, 4-AP first increased and then decreased the amplitude of e.p.p.s. elicited during a train of stimuli of increasing frequency, indicating that 4-AP increased transmitter release more than mobilization.

Aminopyridines↗
PubMed1979

Effect of human chorionic gonadotrophin on phagocytic activity and proliferative capacity of rat peritoneal macrophages in culture.

Human chorionic gonadotrophic hormone (hCG) decreased phagocytosis of rat peritoneal macrophages in culture and also inhibited their capacity to be stimulated by an inflammatory exudate. Both effects were related to the concentration used. These experimental results suggest that elevated levels of hCG may play a role in the prevention of the rejection of the foetal allograft by the maternal host.

Animals↗
PubMed1979

[Biological determination of the beta blocking activity of human serum].

A method of biological assessment of the Beta blocking activity of human serum is reported. It is based on the catecholamine response of rat myocardial cells in culture, incubated in the serum to be tested. Its advantage is that it takes into account all block-blocking substances present in the serum, not only the drug itself but also its possible active metabolites. The results obtained by this method in 10 healthy subjects after 60 mg penbutolol were compared with those given by chemical dosage and ergometry. The ergometric and biological changes were parallel from the 2nd and the 8th hour while the serum levels of the drug rapidly. This discordance could be due to the presence of an active metabolite, 4-hydroxy-penbutolol.

Adrenergic beta-Antagonists↗
PubMed1978

Inhibited response to isoproterenol and altered action potential of beating rat heart cells by human serum in septic shock.

Human serum, obtained within 24 hours after the onset of septic shock, was evaluated for its effects on the chronotropic response of cultured rat myocardial cells to isoproterenol. Transmembrane action potential (AP) was measured in some experiments. Sera obtained after the first four to five hours, when central venous pressure (CVP) was normal or high, inhibited increased cell beats, while this property was not evidenced for samples taken soon after septic shock when CVP was low. Sera were also found to alter AP in much the same way as Sotalol, an adrenergic beta-blocking drug. These two effects were never observed with control sera obtained from healthy male adults at rest. These findings demonstrate that sera from patients in septic shock depress the beta-adrenergic response of rat myocardial cells, after the early phase of septic shock characterized by sympathoadrenergic activity. They strongly suggest the mediation of unidentified humoral factors, which might interfere in the pathogenesis of myocardial dysfunction during the intermediate phase of septic shock.

Action Potentials↗
PubMed1978

Effect of in vivo treatment by dexamethasone and indometacin on DNA synthesis in rat macrophages in culture stimulated by inflammatory exudate.

The acute inflammatory exudate obtained 4 hr after intrapleural injection of dextran in rats is able to induce DNA synthesis and division of normal rat macrophages in culture. The influence on this phenomenon of two types of pretreatment of rats with dexamethasone or indometacin has been investigated. Exudates of rats treated with dexamethasone decreased the DNA synthesis in control macrophages. On the contrary, exudates of rats treated with indometacin had no effect on this DNA synthesis. These results could be explained by the different actions of the two anti-inflammatory agents on cellular migration in pleural exudates. In macrophages harvested from rats treated with dexamethasone or indometacin the DNA synthesis induced by inflammatory exudates was decreased. This identical response elicited by these two agents could be related to their direct antimitotic activity on macrophages.

Animals↗
PubMed1978

The influence of anti-inflammatory compounds on some effects of BCG in the rat.

In the rat, intravenous injection of BCG induced an increase in complement activity, oxidative activity towards paraphenylenediamine and serum haptoglobin level. A strong correlation was shown between oxidative activity and haptoglobin level. These increases were inhibited by glucocorticoids (cortisone, dexamethasone, methylprednisolone) but not by two non-steroidal anti-inflammatory drugs (indometacin, phenylbutazone). It is suggested that these BCG effects are related to the release of macrophage constituents and that this is inhibited by glucocorticoids.

Animals↗
PubMed1977

[Stimulation of the growth of murine bone marrow colonies in vitro by an acute inflammatory exudate. Comparison with colony stimulating factor CSF)].

Formation of colonies from mice bone marrow progenitors of macrophages and granulocytes in methylcellulose culture was induced by an inflammatory pleural exudate obtained from mice injected with dextran. Mitogenic activity of this acute inflammatory exudate was compared with that of colony stimulating factor (CSF). It was found that colony and cluster counts, during 10 days of culture, were similar with the two types of stimulating factors. When used at the same dose, exudate was less active than CSF. It was concluded that inflammatory exudate showed an activity similar to that of CSF but contained a smaller amount of stimulating factor. Further cytochemical studies are necessary to specify whether or not the two factors induced the same type of colonies (monocytic or granulocytic).

Animals↗
PubMed1977

[Increase in spontaneous beating frequency in rat heart cells cultured in homologous serum].

Rat serum at different concentrations added to cultured Rat heart cells medium increased spontaneous beating frequency of myoblasts. This increase occurred instantaneously and lasted more than 24 hrs. It was related to the serum concentration used. Electrophysiological recording showed a decrease in the iso-electric phase duration of membrane potential, with no change in action potential. In spite of the beating frequency increase, cells remained sensitive to the chronotrope positive action induced by Isoprenaline. There was no difference between male and female sera. The global results could partly be explained by the action of Ca++ in Rat serum.

Action Potentials↗
PubMed1977

[Modification of chromatin condensation in cultured macrophages during induction of cell division by an inflammatory exudate].

The determination of chromatin condensation in rat peritoneal macrophages in culture showed a predominance of heterochromatin with low transcriptory activity. After induction of division in rat peritoneal macrophages in culture by an acute inflammatory exudate, a decrease of heterochromatin and an increase of euchromatin were observed. This result brings further evidence to support previous observations according to which this type of exudate shows mitogenic properties.

Animals↗