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Biomedical subjects

P Magnin

Publications and source records attributed to P Magnin.

At least 19 recordsLinked to original sources
PubMed1992

Met-enkephalin, beta-endorphin and cortisol responses to sub-maximal exercise after sleep disturbances.

The present study compared the effects of partial sleep deprivation and the effects of an intake of a hypnotic compound (zolpidem) prior to bedtime, on sleep and on hormonal and metabolic adaptations to subsequent exercise. Sleep deprivation consisted of a delayed bedtime and an early getting-up time. Eight young subjects, who slept well and were highly trained athletes, were enrolled in this study. Sleep was recorded polygraphically and the following afternoon exercise was performed on a cycle ergometer for 30 min at 75% of maximal oxygen consumption (VO2max) after a 10-min warm up. Met-enkephalin, beta-endorphin, cortisol, and lactate concentrations were measured at rest and during exercise. The data obtained after experimental sleep, with and without medication were compared with those obtained in the reference condition with normal sleep. Both types of sleep reduction decreased the total sleep time, stage 2 sleep, and rapid eye movement sleep, whereas zolpidem administration did not modify either the duration of sleep or the sleep stages. After the reference night, plasma met-enkephalin did not show any significant change at the end of the submaximal exercise, whereas beta-endorphin, cortisol, and lactic acid concentrations increased significantly in all subjects. The changes in concentration in beta-endorphin were significantly related to the changes in cortisol (r = 0.78; P less than 0.01) and to the changes in plasma lactic acid (r = 0.58; P less than 0.05). Cortisol concentrations were also related to lactic acid values (r = 0.94; P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Value of sophisticated explorative techniques of the pulmonary function in the preoperative evaluation of respiratory risk].

In order to estimate the preoperative evaluation of the respiratory risk, a well adapted clinical examination associated with a routine pulmonary function test (VC, FEV1) can be sufficient. Although some patients with cardiopulmonary disorders or candidates to lung resection need more complex assessments: the flow-volume loop to detect small airways obstruction (MEF 50%, MEF 25%), measure of bronchial hyperreactivity to predict bronchospasm during anaesthesia, residual volume for the diagnosis of emphysema, diffusing capacity (DCO) to discover lung fibrosis: these parameters disruption always make the pronostic worse. It is also useful to couple together preoperative function test and pulmonary scintigraphy to predict post-operative values after lung resection. But, these criteria for operability are not always a good indicator of post-operative complications. So it is possible to use in addition the results of exercise testing to determine cardio-respiratory performances and maximal oxygen consumption (VO2MAX) which seem better correlated with mortality and post-operative lung surgical complications. Preliminary results of our study concerning thirty patients hospitalized in Besancon-St-Jacques Hospital, agree with the hypothesis that exercise testing is an important criterion in the pre-operative evaluation and to predict post-operative mortality and morbidity of patients candidates to thoracic surgery.

Humans↗
PubMed1991

Simple equilibrium dialysis-high-performance liquid chromatographic method for the in vitro assessment of 5-methoxypsoralen bound to human albumin.

Increasingly used in therapeutics, 5-methoxypsoralen (5-MOP), a linear furocoumarin, associated with UVA irradiation (PUVA), is now an established treatment for skin diseases such as vitiligo, mycosis funcoides and particularly psoriasis. Successful PUVA therapy depends on a sufficiently high peak 5-MOP plasma concentration coinciding with the UVA irradiation. However, as with most drugs, only the free plasma fraction is able to enter the target cells and has a pharmacological effect. In this work, the binding of 5-MOP to human albumin was studied in vitro, using a dialysis chamber. Bound and free 5-MOP fractions were quantified by a modification of Stolk's high-performance liquid chromatographic method. Dialysis was performed at 37 degrees C and pH 7.4 for 2 h, against a 4% albumin solution in phosphate buffer. The 5-MOP concentrations used were from 5 x 10(-5) to 5 x 10(-2) g/l in 1 x 10(-1) g/l steps. The 5-MOP bound strongly to human albumin in an unsaturable way. The mean 5-MOP binding to albumin was 95.3%. These results are in accordance with those published by Artuc et al. and not with those of Veronese et al., who found a lower saturable fixation (91%). These two research groups used tritiated 5-MOP. The technique used in this work is simple and inexpensive. It can be employed easily in vivo, e.g., for the assessment of 5-MOP free fractions in different therapeutic conditions.

5-Methoxypsoralen↗
PubMed1991

Effects of sleep disturbances on subsequent physical performance.

The purpose of the study was to compare the cardiovascular, respiratory and metabolic responses to exercise of highly endurance trained subjects after 3 different nights i.e. a baseline night, a partial sleep deprivation of 3 h in the middle of the night and a 0.25-mg triazolam-induced sleep. Sleep-waking chronobiology and endurance performance capacity were taken into account in the choice of the subjects. Seven subjects exercised on a cycle ergometer for a 10-min warm-up, then for 20 min at a steady exercise intensity (equal to the intensity corresponding to 75% of the predetermined maximal oxygen consumption) followed by an increased intensity until exhaustion. The night with 3 h sleep loss was accompanied by a greater number of periods of wakefulness (P less than 0.01) and fewer periods of stage 2 sleep (P less than 0.05) compared with the results recorded during the baseline night. Triazolam-induced sleep led to an increase in stage 2 sleep (P less than 0.05), a decrease in wakefulness (P less than 0.05) and in stage 3 sleep (P less than 0.05). After partial sleep deprivation, there were statistically significant increases in heart rate (P less than 0.05) and ventilation (P less than 0.05) at submaximal exercise compared with results obtained after the baseline night. Both variables were also significantly enhanced at maximal exercise, while the peak oxygen consumption (VO2) dropped (P less than 0.05) even though the maximal sustained exercise intensity was not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Pharmacological interactions between diltiazem and thiopental. A study on an electrophysiological model of guinea pig isolated papillary muscle. Value of positive inotropic agent].

This study was designed to assess in vitro the effects of Thiopental alone and Thiopental--Dobutamine association on control and on Diltiazem pretreated papillary muscle. The Diltiazem treatment do not increase the negative inotropic effect of Thiopental but the effect of Dobutamine is less important in pretreated group. The Diltiazem treatment protect to arrhythmogenic action of Thiopental and Thiopental-Dobutamine association.

Animals↗
PubMed1990

[In vitro study, in perfused rabbit heart, of interaction between two anti-arrhythmia agents: amiodarone and disopyramide].

The influence of 15 day's amiodarone administration (30 mg/kg/day) on myocardial uptake kinetics and electrocardiographic changes of disopyramide was examined on the isolated perfused rabbit heart (n = 24) under electrical stimulation. Amiodarone significantly reduced myocardial uptake and potentialized the effect of disopyramide on intraventricular conduction.

Amiodarone↗
PubMed1990

[Pediatric anesthesia and pharmacokinetics of propofol administered at a constant rate].

The pharmacokinetic properties of propofol given at a constant rate, were studied in 10 children. Propofol was administered at a dose according to I.C.I. Pharma advices. For minor surgery, a low quality of general anesthesia was observed in correlation with low plasma levels of propofol. An increase in dosage would be necessary in children above 8 years old.

Adolescent↗
PubMed1989

Preliminary results of nuclear magnetic resonance studies of healthy human saliva.

Relaxation times T1 and T2 of water protons for stimulated and unstimulated parotid and submandibular saliva from healthy patients were measured in the conventional way using the Bruker PC 20 Minispec. Some measurements of dispersion were also carried out. An interpretation of the average values for T1 and T2 observed in the 20 MHz range is proposed for these types of saliva in relation to biochemical composition (total proteins, amylase activity, sialic acids and hexosamins) and viscosity. For parotid saliva T2(-1)-T1(-1) correlates significantly with amylase activity. In the submandibular saliva T2(-1)-T1(-1) correlates significantly with both mucins and alpha-amylase activity.

Amylases↗
PubMed1989

[Pharmacologic aspects of sleep disorders].

Sleep disorders are becoming a major issue. Insomnia affects a substantial part of the population and may compromise individual quality of life. The principal existing hypnotic drugs, Barbiturates and Benzodiazepines are not safely. They have modes of action which results in the action of common mechanism: facilitating neurotransmission in GABAergic synapses. Stimulation of GABA receptors of the A type opens chloride ion channels which inhibits the ability of neurons to conduct nerve impulse. The clinical effects resulting which induce anticonvulsant, muscle relaxant, anxiolytic, sedative, hypnotic and amnesic effects are discussed.

Animals↗
PubMed1989

[Antispasmodic effect of warm water administered in aerosols or parenteral injections].

The aerosol of thermal water given just before the administration of spasmogenic substances did not prevent the histamine or acetylcholine induced bronchospasm. After a daily parenteral dose of thermal water during 21 days, a systemic delay of the bronchospasm induced by both mediators was observed. With arsenic pretreatment the delay in onset of bronchospasm was shorter.

Acetylcholine↗
PubMed1989

[Disturbance of sports performance after partial sleep deprivation].

The changes in cardiac and ventilatory responses were measured in 7 endurance athletes during physical exercise on a bicycle ergometer, taking place after a control night and after a night with partial sleep deprivation in the middle of the night. The results show that, despite the maximal work load was not modified with control, heart rate, ventilation and VE/VO2 ratio (ERO2) were greater at the submaximal (75% of the VO2 max) and maximal work load and oxygen consumption decreased at maximal work, after the night of partial sleep deprivation as compared to the control. These findings suggest that acute sleep loss may contribute to alter the endurance performance by impairment of aerobic pathways.

Adult↗
PubMed1988

[Recent data on the mechanism of action of theophylline].

Since Sutherland's work simply based on the inhibition of phosphodiesterase was questioned, other researches have been carried out, indicating that many mechanisms located in the nervous system, the smooth muscle, and the immunity system interfere. The participation of receptors to adenosine, intracellular calcium ions, regulating calciproteins and autacoids such as prostaglandins was the purpose of numerous experimental researches that allow today to fill up the gap left by the fact that the inhibitor of phosphodiesterase was questioned. However, there are not sufficient but there are many seducing research and hypotheses.

Adenosine↗
PubMed1987

Oxidation-reduction potential studies: a new method in pharmacology principles, materials, and methods.

Oxidation-reduction (redox) potential measurement is not used in pharmacology at the present time. However, it represents a physicochemical parameter that may be as important as the other currently used physicochemical parameters, such as pH and pKa. Redox potential variations include conformational modifications that may influence bioavailability of drugs. We report here an original and convenient equilibrium method to determine this potential in biological fluids, especially in blood.

Female↗