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Biomedical subjects

F Lhoste

Publications and source records attributed to F Lhoste.

At least 73 records · Page 4Linked to original sources
PubMed1976

[Severe hyperkalemia in cardiac patients].

Hyperkalaemia with severe myocardial consequence may complicate the treatment of heart failure. In five patients who developed kalaemia ranging from 6.5. to 8.6. mEq/l, the ECG showed altered auriculogram and/or widened QRS, the latter change being associated with ST segment elevation and very large T wave in one case. Such hyperkalaemia cannot be termed iatrogenic, although it is promoted by diuretic-induced hyponatraemia and dehydration. The essential part is played by an aggravation of the haemodynamic status, responsible for acute renal insufficiency with oligoanuria, and by the attendant metabolic acidosis. The correction of this metabolic acidosis promotes diuresis, causing potassium depletion and the rapid regression of electrocardiographic abnormalities. Parenteral alkalinization with sodium bicarbonate, associated with furosemid to prevent sodium overload, instituted in emergency, is the only way to prevent asystole or ventricular fibrillation when kalaemia exceeds 8 mEq/l.

Acidosis↗
PubMed1976

Isoprenaline and canine cardiac refractory periods.

Atrioventricular refractory periods and their modifications induced by variable doses of sioprenaline have been investigated in dogs. Premature atrial stimuli (St2) were applied at variable intervals following regular stimuli (St1) which ensured atrial pacing. Atrial (AERP), nodoventricular (NERP) and global (GERP) effective refractory periods, as well as the global functional refractory period (GFRP) were determined before, during and after infusion of the drug. In low doses, isoprenaline did not significantly alter these various parameters. This confirms its lack of dromotropic effect on the healthy heart. In contrast, high doses of the drug significantly reduced the refractory periods, probably by simple correction of the negative dromotropic effects resulting from overstimulation. Also when the infusion was stopped, marked but reversible conduction depression was observed. It would appear that this reflects 'exhaustion' of cell metabolism induced by the drug.

Animals↗
PubMed1976

Anti-beta adrenoreceptor blockade activity of plasma ultrafiltrate in two uraemic patients: effect of parathyroidectomy.

A possible interaction between d-1 propranolol and hyperparathyroid plasma ultrafiltrate on guinea pig auricles has been studied in "in vitro" experiments. Plasma ultrafiltrates have been samples in two patients on chronci haemodialysis before (pre-PTx) and after (post-PTx) parathyroidectomy. A significant inhibition of propranolol depressant activity on cardiac contractile strength has been observed in the presence of pre-PTx plasma ultrafiltrates. On the contrary, no such inhibition was noted in the presence of post-PTx plasma ultrafiltrates.

Animals↗
PubMed1975

Beta-adrenergic blockade and atrio--ventricular conduction impairment.

Atrio--ventricular conduction and its modifications induced by six Beta-adrenergic blocking agents have been investigated in the dog. Premature atrial stimuli (St2) were applied at variable intervals following regular stimuli (St1) ensuring atrial pacing; atrial (AERP), nodoventricular (NERP) and global (GERP) effective refractory periods as well as global functional refractory period (GFRP) were determined before and after administration of each of the six drugs. When Beta-blockade was produced with d,1-propranolol which hwas membrane stabilizing effects (MSE) but no intrinsic sympathomimetic activity (ISA) or with sotalol, which has neither MSE nor ISA, all parameters were significantly increased. When Beta-blockade was achieved with pindolol or practolol, which have only a poor Beta-adrenolytic potency and no ISA. Alprenolol showed intermediate effects. Thus, it appears that Beta-blockade and not MSE, is responsible for the onset of A-V conduction impairment but that ISA, probably through a metabolic mechanism, affords protection against this impairment. On the other hand, measurement of ventricular effective refractory period (VERP) has shown that at the Purkinje-free junction, it is MSE which is mainly involved in conduction impairment.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Diseases and drug protein binding.

In a number of pathological states a decrease in the plasma protein binding of drugs is observed. This may be due to many factors related either to the protein, or the ligand (drug), or to the binding conditions. The most important of these disease states quantitatively are probably hypoalbuminaemia, conditions resulting in modification of the albumin compartment volume and the presence on albumin binding sites of pathological inhibitors of drug binding. A decrease in the extent of drug plasma protein binding does not necessarily lead to enhanced drug effects and therefore raises two important therapeutic questions. Firstly, does reduced protein binding have a clinically significant influence on the pharmacological effects of the drug? Secondly, if it does, is it preferable to modify the dosage regimen of the drug or to correct the plasma protein concentration prior to the administration of the drug? At present, only tentative answers can be given.

Bilirubin↗
PubMedDate not supplied

Is uranyl scavenger hexakis(3,6-anhydro) tetrakis(2A,B,D,E-O-octyl) cyclomaltohexaose (OCT) relevant with biosystems?

Hexakis(3,6-anhydro)tetrakis(2A,B,D,E-O-octyl) cyclomatohexaose (OCT) has been recently shown as a powerful cryptant for lead, mercury, and especially for uranyl. As previous results have been obtained in an organic solvent (methanol), a similar evaluation of OCT complex formation was achieved in aqueous medium and in the presence of membrane-mimicking systems such as phospholipid vesicles, liposomes and micelles. It was found that OCT, while completely insoluble in water, forms solid gel structures when in equimolar mixtures of water and methanol. Moreover, OCT exhibits detergent properties. Finally, OCT was successfully introduced in detergent solutions while keeping. Uranyl complexing properties. Possible applications of such models were also discussed.

Chelating Agents↗
PubMedDate not supplied

1H-NMR study of heavy metals complexation with hexakis(3,6-anhydro) tetrakis(2A,B,D,E-O-octyl) cyclomaltohexaose (OCT).

The selection of the cations bound by hexakis (3,6-anhydro) tetrakis (2A,B,D,E-O-octyl) cyclomatohexaose (OCT) was performed by thin layer chromatography. The three cations selected, UO(2)2+, Pb2+ and Hg2+ were then studied by 1H-NMR. A 2:1 OCT/cation stoichiometry was identified in the cases of UO(2)2+ and Pb2+. While UO(2)2+ binding (logK around 6) followed a fast exchange kinetics, a slow or intermediate complexation was found with Pb2+ (logK = 5.6) and Pb2+, respectively. In the latter case, the poor solubility of Hg2+ precluded to propose neither a stoichiometry nor an estimation of the affinity constant.

Chelating Agents↗
PubMedDate not supplied

Effects of six beta-blockers on the isolated guinea-pig trachea.

The effects of six beta-blocking agents (propranolol, metoprolol, atenolol, pindolol, medroxalol and labetalol) selected on the basis of their intrinsic sympathomimetic properties, membrane-stabilizing activities and selectivity for beta 1-adrenoceptors were investigated on the isolated guinea-pig trachea. Tracheal spirals were either allowed to remain under resting tension or were precontracted with histamine 2 X 10(-6) M or 2 X 10(-5) M. Pindolol, medroxalol and labetalol exerted a moderate relaxant effect on tracheal muscle. This effect was inhibited by propranolol, but not significantly modified by indomethacin. Propranolol and metoprolol exerted a moderate contracturant effect on the preparations. The effect was inhibited by indomethacin but not by FPL 55712. Atenolol had no effect on tracheal muscle. This in vitro study provided data concerning two properties of beta-blockers--intrinsic sympathomimetic and membrane-stabilizing activities--which are involved in the bronchomotor response to these drugs in vivo.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

[Use of cardiotonic heterosides in pediatrics].

The indications for the administration of cardiotonic heterosides are quite similar in adults and children. However, their use in children raises several practical problems, generally related to differences in kinetics and/or tissular sensitivity. The pharmacodynamic properties and the kinetics of cardiotonic glycosides of digitalis are reviewed and therapeutic and toxicologic effects are discussed.

Age Factors↗
PubMedDate not supplied

[Effects of histamine on the pressure-volume curve of the respiratory system in the guinea pig].

Intravenous infusion of histamine has been shown to constrict smooth muscle of alveolar ducts. In this study, we have assessed the effects of a prolonged infusion of histamine to obtain a steady state response on quasistatic pressure-volume curves (P-V curves) together with the changes in dynamic compliance (Cdyn) and conductance (G) of the respiratory system. Increasing doses of histamine were given in order to obtain the dose-response characteristics of the changes in Cdyn, G and P-V curves. In nine anesthetized guinea-pigs under mechanical ventilation, administration of histamine resulted in a fall in Cdyn and G with a decrease of 50% of initial value approximately for 150 ng X kg-1 X s-1 of histamine. Modifications of the P-V curves were characterized by a decrease in the maximal volume, and an increase in the hysteresis of the P-V loop due to the downward displacement of the inflation limb. With infusion of histamine, there was a large decrease of quasi-static compliance which appeared to account for most of the decrease in dynamic compliance. Such changes in P-V curves can be related both to a closure of alveolar ducts and to an alteration of lung distensibility. Comparison of the dose-response curves for the different parameters indicated that Cdyn and G reflect, at least in part, events occurring in the periphery of the lung.

Animals↗
PubMedDate not supplied

Bromocriptine and genetic hypertension development in young spontaneously hypertensive rats.

The effects of bromocriptine (BRC; 20 mg X kg-1, b.i.d., orally) on genetic hypertension development (GHD), cardiovascular hemodynamics, regional vascular reactivity to vasopressor agents and biological parameters have been investigated in spontaneously hypertensive rats (SHRs) treated from their 4th to 20th weeks of age. BRC only partially opposed GHD and this was due to a limitation of the progressive increase in peripheral resistance which normally develops in SHRs with ageing since simultaneously cardiac index was not modified. Renal blood flow was increased and renal and mesenteric vascular responsiveness to norepinephrine was reduced. BRC almost completely suppressed prolactin plasma levels and slightly reduced epinephrine and norepinephrine plasma levels. Plasma Na+ and urinary volume and ADH values were not modified. The discrepancy between the favourable antihypertensive profile of BRC and its limited preventive effects against GHD remains to be elucidated.

Aging↗