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Biomedical subjects

E Labeyrie

Publications and source records attributed to E Labeyrie.

12 recordsLinked to original sources
PubMed2000

[Hormone replacement therapy after endometrial or ovarian cancer].

Use of hormonal replacement therapy after treatment of ovarian or endometrial cancer remains a matter of debate. Novel adjuvant therapies tend to increase the survival of these patients, who are exposed to risk factors of hormonal deficiency subsequent to primary therapy. Therefore, the aims of the present review of literature was to analyse epidemiologic and clinical parameters on behalf on hormonal replacement therapy in this population.

Endometrial Neoplasms↗
PubMed1989

A dynamic analysis of the ventilatory response to hypoxia in man.

1. The dynamics of the ventilatory response to isocapnic hypoxia were studied in seven healthy subjects using four different levels of hypoxia, (inspired oxygen pressures, PI,O2 equal to 110, 100, 80 and 60 mmHg) successively increasing and decreasing stepwise. 2. Five such progressions were performed for each subject, corresponding to five different durations of the steps (t) ranging between 0.33 and 5.00 min. The overall duration of one test (T) was taken as the sum of the seven successive PI,O2 hypoxic steps (t) plus one step t of air breathing. Thus, the values of T ranged between 2.6 and 40.0 min. 3. End-tidal CO2 pressure was maintained constant (+/- 1 mmHg) throughout the test by manipulation of inspired CO2 pressure. 4. We measured, as a function of T, (i) the magnitude of the loops formed by the ventilatory response curves (PA,O2-VE) as measured by their surface area (S), (ii) the magnitude of ventilatory response to each rising hypoxic step, and (iii) the difference between resting VE and VE observed at PA,O2 equal to 50 mmHg (delta V50). On average, we found one maximum in absolute value of S at T = 8 min and one minimum at T = 12 min, along with two maxima of ventilatory response at T values of 8 and 24 min. 5. The same measurements were made on tidal volume response curves (PA,O2-VT) and ventilatory frequency response curves (PA,O2-f): on average we observed two non-significant peaks in the progression with T of VT and S(VT) and two significant peaks in that of delta VT,50 for T = 8 and T = 24 min. No significant peak was observed in the progression with T of f curve parameters. 6. These results are discussed together with the current dynamic model of the ventilatory control system, which includes a central neural controller with no dynamics of its own and a linear response to chemoreceptor inputs. We discuss the physiological meaning of a negative loop area in relation to the previously described depressant effect of hypoxia upon the brain stem. 7. We conclude that the dynamics of the controlling neuronal network are responsible for the observed singularities which result from differential sensitivity properties of the controller. We propose the existence of discrete excitatory states of the controller as a possible explanation of the shape of the steady-state response curve to hypoxia and of the loop variations.

Adult↗
PubMed1988

A dynamic analysis of the ventilatory response to carbon dioxide inhalation in man.

1. The dynamics of the ventilatory response to carbon dioxide inhalation were studied in ten healthy young men using four different inspired fractions of carbon dioxide (FI, CO2) in air (0.015, 0.030, 0.045 and 0.060) successively increasing and decreasing stepwise. 2. Seven such different progressions were performed for each subject and each of seven different durations of the steps (t) ranging between 0.1 (i.e. one ventilatory cycle) and 10 min ('steady-state' conditions). The overall duration of one test (T) was taken as the sum of the seven successive FI, CO2 steps (t) plus one step, t, of air breathing. Thus, the values of T ranged between 0.8 (i.e. eight ventilatory cycles) and 80 min. Three subjects were tested twice. 3. We measured, as a function of T, the magnitude of the loops formed by the curves PA, CO2-VE and the value of the highest ventilatory response (VE max) to each progression. For all ten subjects, both functions had two maxima, one for T values of 2.6 or 8.0 min and one for T values of 24 or 40 min, and one minimum at T equal to 12 min. 4. The same measurements were made on tidal volume-response curves (PA, CO2-VT) and ventilatory frequency-response curves (PA, CO2-f) and yielded the same results except for the ventilatory frequency-response curves, for which we only found a statistically insignificant single maximum for T values of 24 or 40 min. 5. The locations of the maxima in loop magnitude and VE max were similar in duplicate tests in three subjects, whereas the quantitative values of these variables showed wide differences. 6. We compared our results with what is expected from the current linear dynamic model of ventilatory control submitted to the same forcing function: the first maximum in the loop magnitude is predicted by the model, but the second is not. The model shows no peak in the evolution of VE max. 7. We conclude that controlled system dynamics, which are the only ones included in dynamic models of ventilatory control, cannot by themselves account for our observations, and that one should take into consideration the dynamics of the controlling neuronal network.

Adult↗
PubMed1985

[Not Available].

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Economics, Medical↗
PubMed1983

[Dynamic study of the diffusion and clearance of proteins in human interstitial tissue].

The application of a venous tourniquet leads to distension of the distal venous and capillary circulation and a local increase in plasma volume. In the normal subject, plasma volume returns to its initial level within approximately 10 sec of tourniquet release. In subjects affected by cyclical oedema, the local increase in plasma volume persists several minutes after tournique release. Radioactive labelling of plasma proteins shows that this delay is associated with the retention of plasma proteins by the tissues. These proteins are subsequently cleared by lymphatic drainage or diffusion back into veins. These results suggest that the combination of tournique test with the labelling of plasma proteins measures capillary and venous permeability as well as tissue protein clearance kinetics.

Body Fluid Compartments↗
PubMed1982

[Mechanism of action of benzothiadiazides in arterial hypertension: the energetic theory].

Hydrochlorothiazide, tienilic acid, chlorthalidone and indapamide inhibit membrane adenylate cyclase of pigeon erythrocytes in vitro. This effect is related to the action of these substances on the interface between the membranous phospholipids and adenylate cyclase. Indapamide with its strong lipophic properties, has a more specific action on the intracellular regulation of adenylate cyclase. The relationship between the inhibition of adenylate cyclase and the antihypertensive effects of these drugs is discussed.

Adenylyl Cyclase Inhibitors↗
PubMed1979

Photoelectrode with a very short time-constant for recording intracerebrally Ca2+ transients at a cellular level.

In order to study calcium transients in the central nervous system of vertebrates a microphotoelectrode was designed. It is composed of three channels, through the first aequorin is perfused into the extracellular space under constant pressure, the second is an optical glass light-conducting channel, and the third a classical NaCl-filled recording pipette. The light emitted by the interaction of the injected aequorin with the local extracellular calcium is transmitted through the optic fiber to a photomultiplier of high sensitivity.

Aequorin↗
PubMed1976

[Increased transmission at electronic synapses and paroxysmal depolarization induced by cardiazol in the Mauthner cell].

Cardiazol induces in the Mauthner cell the paroxysmal depolarizing shifts which are characteristic of epilepsia at the neuronal level. The period of depolarizations is preceded and, later, accompanied by an increased transmission at the electrotonic synapses which are established upon this neuron by primary afferent vestibular fibers. Increased excitability of the chemical synapses occurs subsequently.

Animals↗
PubMed1976

[Evaluation of the opening of the sphincter of Oddi].

Measurement of the activity of the sphincter of Oddi by the method of classical manometry did not reveal any significant difference before and after vagotomy. However, the existence after perfusion of residual pressure greater than initial pressure, suggests that a deformity of the duct during perfusion disturbs measurement of the opening of the sphincter. The mechanical properties of the duct were measured in vitro, as a first approximation it was suggested that the error due to a deformity of the duct, might be eliminated using several perfusion rates and calculating for each rate the opening R of the sphincter using the following formula: R equals (Perfusion pressure-Residual pressure) Flow rate. When the opening of the sphincter is calculated in this way, one may observe that vagotomy leads to definite reduction of the resistance of Oddi's sphincter.

Ampulla of Vater↗