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Biomedical subjects

M Lesne

Publications and source records attributed to M Lesne.

At least 19 recordsLinked to original sources
PubMed1988

Comparison of the pharmacokinetics and pharmacodynamics of torasemide and furosemide in healthy volunteers.

The pharmacodynamic effects and the pharmacokinetic parameters of torasemide (1-isopropyl-3- ([4-(3-methyl-phenylamino)pyridine]-3-sulfonyl)urea) 20 mg and furosemide 40 mg were compared after oral and intravenous administration in 6 healthy volunteers. The plasma elimination half-life for i.v. and oral torasemide was 2.2 h and 2.8 h, its bioavailability after oral administration was 91%, about 25% of the total body clearance was due to renal excretion both after iv. or oral application. For furosemide, a plasma elimination half-life of 0.6 h for i.v. and 0.8 h for oral application was found. The bioavailability was 40%, and about 62% of the drug was excreted via the kidney. Both drugs produced a similar diuretic and natriuretic effect. However, torasemide showed an increased duration of action compared to furosemide and a higher relation between urinary Na and K excretion, both after i.v. and oral administration, suggesting less loss of potassium after To. Both agents were well tolerated.

Administration, Oral↗
PubMed1987

Benzodiazepine receptors are involved in tabernanthine-induced tremor: in vitro and in vivo evidence.

Tabernanthine, an indol alkaloid, is structurally related to carbolines (harmane, harmaline) which, in vitro, displace specific flunitrazepam binding to brain benzodiazepine receptors. In vivo, both tabernanthine and carbolines cause a fine general tremor, suggesting that a possible interaction with benzodiazepine receptors could be involved in the activity of tabernanthine. This hypothesis was validated by the in vitro and in vivo antagonism of benzodiazepine by tabernanthine. In vitro, tabernanthine inhibited specific flunitrazepam binding in a competitive manner with an affinity (IC50 150 microM) in the same range as harmane. Tabernanthine appeared as a benzodiazepine receptor inverse agonist in a discriminant in vitro binding assay. In vivo, the time course of tremorigenic activity was related to the tabernanthine concentration in brain (half-life = 2 h). Moreover, tabernanthine-induced tremor was inhibited reversibly by flunitrazepam or by Ro-15 1788 (an antagonist of benzodiazepine-receptors). These results suggest that part of the action of tabernanthine may be mediated by an interaction at the benzodiazepine receptor level.

Alkaloids↗
PubMed1987

New automated high-performance liquid chromatographic analysis of cyclosporin A and G in human serum.

An automated isocratic high-performance liquid chromatographic (HPLC) method is described for the determination of cyclosporin A and G in human serum. This method involves the use of an automated solid-liquid extraction procedure following rapid protein precipitation with acetonitrile. The use of a disposable C8 extraction cartridge allows a good recovery of cyclosporine (87%) from serum and a detection limit of 20 ng/ml with good reproducibility using 0.5 ml of sample. This method can also be adapted to whole blood measurements. The choice of a 3-micron cyano analytical column and of the mobile phase hexane-isopropanol (85:15) permitted a low column temperature (50 degrees C), a low flow-rate (0.6 ml/min) and a short run time (14 min). This method allows the accurate and fast routine monitoring of cyclosporine by HPLC, which is particularly important in hepatic transplantations.

Autoanalysis↗
PubMed1987

The quantification of gamma-aminobutyric acid in the cerebrospinal fluid by a radioreceptorassay.

The development of a radioreceptor assay designed to measure gamma-aminobutyric acid (GABA) in CSF is described. The method is based on the presence of high affinity and selective GABA binding sites obtained from rat brain membrane preparations treated with 0.05% Triton X-100. The optimum protein concentration in the incubation medium, the duration of incubation to reach equilibrium, the temperature and the optimum pH are discussed. The standard curve permits measurements in the range 35 to 2250 nmol/l GABA. The imprecision of the method calculated from three different concentrations: 1125, 562 and 281 nmol/l shows coefficients of variation for 'within' and 'between' assays, between 5.2% and 9.3% and between 7.4% and 12.4%, respectively. The percentage of recovery is 102 +/- 3.3% (n = 4). This radioreceptorassay has a sensitivity of 14 nmol/l. The method is easy, rapid and not expensive. It enables analysis of small volumes of CSF (200 microliters). Several samples (greater than 20) can be analysed in the same run in about one hour.

Animals↗
PubMed1986

Selective affinity of one enantiomer of suriclone demonstrated by a binding assay with benzodiazepine receptors.

The binding of racemic 3H-suriclone on the BZD receptor was performed in special conditions in order to discriminate between the affinity of the two enantiomers: a rebinding method was used. In the first incubation 40% of 3H-suriclone was specifically bound to the BZD receptor. In the second incubation performed with the supernatant coming from the first incubation, less than 1% of the radiolabelled suriclone was specifically bound to the BZD receptor. These results suggest that most probably only one of the two enantiomers of suriclone may bind the BZD receptor. It appears that this enantiomer has the greatest affinity constant ever found for a BZD receptor agonist (Kd = 20 pM at 37 degrees C in presence of GABA and 70 pM in absence of GABA).

Animals↗
PubMed1979

The binding of gitoxin to human plasma proteins.

The binding of gitoxin, digitoxin and digoxin to human plasma proteins was measured by ultracentrifugation and equilibrium dialysis. At concentrations in the range of therapeutic plasma levels, protein binding amounted, respectively, to 85, 92 and 20%, the last two values being consistent with data reported in the literature. The affinity of purified human albumin was not significantly different for the three cardiac glycosides tested. No other protein than albumin was found to bind gitoxin in human plasma.

Blood Proteins↗
PubMed1979

Digoxin acute intoxication: evaluation of the efficiency of charcoal hemoperfusion.

Since there is no widely used method of reducing the severity of massive digoxin intoxication, the capacity of hemoperfusion with coated, activated charcoal to remove digoxin was evaluated in a case of suicidal digoxin ingestion (25 mg). Seven hours after ingestion the digoxin plasma level was equal to 8.9 ng/ml. This was decreased to 4.5 ng/ml after 6 hr hemoperfusion. The amount of digoxin adsorbed by the column represents 4.8% of the absorbed dose. At a blood flow rate of 170 ml/min, the mean digoxin clearance by hemoperfusion was 44.5 +/- 26.9 ml/min. From these results we conclude that charcoal hemoperfusion in acute digoxin intoxication is of little value.

Adult↗
PubMed1979

Bioavailability study of gitoxin in a solid dosage form.

Although the cardiotonic activity of gitoxin is known for almost half a century, this digitalis glycoside has never been used in therapy, due to its apparent lack of resorption after administration by oral route. Recent studies have demonstrated that the bioavailability of gitoxin could be upraised to 100% provided it be given as a hydroalcoholic solution. The present paper deals with the development of a solid dosage form (tablets) using a physical association of gitoxin and sodium escinate.

Adult↗
PubMed1979

[Placental sulfatase deficiency and sex-linked recessive ichthyosis. Two cases found in two sisters (author's transl)].

The diagnosis of placental sulfatase deficiency was made at the same time in two sisters who were pregnant. This is the first case history reported of two women who were carriers of this abnormality and who were linked by parentage. The inborn error of metabolism was able to be found in its post-natal state in two of the sons of one of the women in the form of retention cutaneous ichthyosis of a sex-linked type.

Adult↗
PubMed1978

Pharmacological reevaluation of gitoxin in man.

The aim of the present investigation was to reevaluate the pharmacokinetic and pharmacodynamic parameters of gitoxin in man. Gitoxin given as a solution is quasi-completely absorbed after oral administration in a fasting man. A dose of 1.5 mg modifies the left ventricular ejection time index (LVETI) as digoxin or digitoxin does. The biological half-life of gitoxin calculated on the basis of plasma concentrations or urinary data is about one day. The urinary elimination of gitoxin is smaller than 21% of the dose. Therefore the two main advantages of gitoxin versus digoxin or digitoxin are: 1) its short biological half-life and 2) its elimination being less dependent on the renal function of the patient.

Administration, Oral↗
PubMed1977

Development of a radioimmunoassay for aprindine.

We have developed a radioimmunoassay for aprindine, a new antiarrhythmic drug used in the treatment of ventricular disorders. The antibodies were produced by immunization of New-zealand rabbits with aprindine coupled to human serum albumin. Their biochemical characteristics have been determined. Tritiated aprindine was used as radioactive competitor. The cross-reactivity with several metabolites of aprindine was studied too. Finally, the results obtained by RIA in plasma and tissues of dogs were compared to those obtained by gas-chromatography.

Animals↗