Biomedical subjects

L Barthelemy

Publications and source records attributed to L Barthelemy.

At least 19 recordsLinked to original sources

PubMed1993

[Activity of plasma dopamine-beta-hydroxylase in newborn infants. Implication in prematurity, maternal pathology and growth].

The aim of the study was to determine plasma dopamine-beta-hydroxylase activity (DBH) in newborn infants and possible changes with maturation, mode of delivery and maternal disease: pregnancy-induced hypertension and gestational diabetes. DBH activity was determined by high performance liquid chromatography from 82 neonates divided in 2 groups: group I: 27 neonates (age: 1 to 8 days) including 6 preterm and 21 full-term neonates; group II: 55 full-term neonates divided in 5 classes: A: vaginal delivery; B: forceps; C: elective caesarean section; D: vaginal delivery and maternal hypertension; E: vaginal delivery and gestational diabetes. The plasma DBH activity was low in neonates and not influenced by prematurity. Significantly lower DBH activity was found after caesarean section. Hypertension and gestational diabetes did not affect umbilical cord plasma DBH activity.

Adult↗

PubMed1992

[Neurotransmission and sudden infant death. Study of cerebrospinal fluid].

The study of 33 cerebrospinal fluids of infants victims of sudden death shows a very significant increase of the metabolites of dopamine and serotonin. These determinations, compared to a control group, indicate a failure, concerning these two neurotransmitters, which could induce a cardiorespiratory seizure. This failure has likely a multifactorial origin.

Heart Arrest↗

PubMed1992

Changes in striatal and cortical amino acid and ammonia levels of rat brain after one hyperbaric oxygen-induced seizure.

Changes in amino acids (AA) and ammonia were investigated in the cerebral cortex and striatum of rats after the following conditions: 1) one hyperbaric oxygen (HBO)-induced seizure (6 ATA O2); 2) exposure to 6 ATA air; and 3) exposure to atmospheric pressure (no seizures in both latter groups). Exposure to 6 ATA air produced no change with respect to atmospheric pressure. After HBO seizure, AA levels (except for gamma-amino butyric acid, GABA, and glutamine), with respect to 6 ATA air levels, were altered in the striatum with a concomitant rise in ammonia (+70%) at variance with the cortex. These changes could be explained by increased oxidative deamination in the striatum. Decrease in taurine content (-66%) in the striatum, where HBO lipoperoxidation exists, suggests an alteration of glial function leading to blockade of uptake and loss of released products in interstitial fluid. This pattern of change recalls the one seen in ischemic conditions, but cannot be confirmed in the absence of measurements of extracellular amino acid levels under HBO conditions. The maintenance in the level of GABA would favor its role in controlling seizure. In the cortex, only a few AA levels decreased, along with a nonsignificant trend for ammonia to increase. The remaining abnormalities in the striatum, after the first HBO seizure, may explain the already known repetition of seizures in continuously exposed animals and are consistent with previous data on the important role of the striatum.

Amino Acids↗

PubMed1991

The influence of one hyperbaric oxygen-induced seizure on brain eicosanoid content.

The levels of prostaglandin F1 (6-keto-PGF1 alpha), thromboxane B2 (11-dehydro-TxB2), and peptidoleukotriene C4 (LTC4) were measured (acetylcholinesterase immunoassay) in the frontal cortex (FC) and the striatum (SA) of the rat brain to study the possible role of eicosanoids in seizures induced by hyperbaric oxygen (HBO). The rats were exposed to (1) hyperbaric oxygen (HBO, 6 ATA O2) up to the first seizure (2) compressed air (6 ATA air, i.e., approximately equal to 1.25 ATA O2) or (3) atmospheric pressure (1 ATA air, i.e., 0.21 ATA O2); there was no seizure in groups 2 and 3. Transition from 6 ATA to atmospheric pressure was obtained in 15 min; the rats were then decapitated and their heads frozen in liquid nitrogen before extraction and analysis of prostanoids. Whatever the conditions, cortical levels of 6-keto-PGF1 alpha and 11-dehydro-Tx B2 are higher than striatal levels; considering the same area, 11-dehydro-Tx B2 and LTC4 concentrations were not significantly different whatever the condition, but there is a trend for lower 6-keto-PGF1 alpha levels in FC after HBO seizure. Biochemical mechanisms are discussed. Eicosanoids do not seem to play a major role in HBO seizures, although some modifications of their metabolism may take place.

Animals↗

PubMed1990

CO2 chemoreflex drive of ventilation in man: effects of hyperoxia and sex differences.

CO2 single breaths have been performed in 7 men and 7 women in conditions of normoxia (FICO2 congruent to 0.13; FIO2 congruent to 0.21; FIN2 congruent to 0.66) and of hyperoxia (FICO2 congruent to 0.13; FIO2 congruent to 0.87). Ventilatory responses of the subjects and modifications of breathing pattern in the course of the CO2 tests were also explored in the two conditions. The results (mean +/- SEM) show that, whatever the oxygenation, men and women exhibit the same ventilatory response during a CO2 test from a qualitative point of view but with a smaller intensity in women (men: 0.37 +/- 0.088 LBTPS.min-1.Torr-1; women: 0.15 +/- 0.025 LBTPS.min-1.Torr-1; p less than 0.05). Considering men and women together, CO2 tests induced an increase of minute volume VE (p less than 0.001), VT (p less than 0.01) and rate of breathing (NS) but this response is decreased in hyperoxic conditions (p less than 0.05) mainly in men (men: 0.19 +/- 0.043 LBTPS.min-1.Torr-1; women: 0.11 +/- 0.023 LBTPS.min-1.Torr-1). These results show that sensitivity to transient hypercapnia and its interaction with hyperoxia are weaker in women than in men.

Adult↗

PubMed1990

[Abnormalities of respiratory function in civil defence firefighter-submarine divers. Respective role of diving and occupational exposure related to occupational firefighter's functions].

Lung function was studied in 20 firemen-submarine divers (mean age 36 +/- 1.2 years) of the French civil defence undergoing the medical check-up compulsory for professional divers (lung function tests are not systematically performed in ordinary firemen). Compared with the CECA standards: (1) vital capacity (VC) was increased, residual volume (RV) was decreased and total lung capacity (TLC) was unchanged; (2) with the exception of peak respiratory flow, all expiratory flow values (FEV1, MEF50, MEF25) were decreased; (3) the permeability factor (KCO) was decreased. These functional abnormalities were moderately worse in subjects who smoked. Some abnormalities (increased VC, decreased RV) are typical of diving activities, but the deterioration of effort-dependent expiratory flow values and alveolar-capillary diffusion must be ascribed to specific nuisances (fumes, polluants, toxic substances) associated with fireman's activities. Monitoring lung function in all professional firemen therefore seems to be necessary, if not indispensable.

Adult↗

PubMed1990

Ammonia and monoamine concentrations in two brain areas in rats after one hyperoxic seizure.

Monoamines (catecholamines, serotonin, and metabolites) and ammonia were studied within two areas of the rat brain--the frontal cortex (FC) and the striatum (SA)--after exposure to hyperbaric oxygen (HBO) at 6 ATA up to the first seizure. An increase of norepinephrine (NE), dopamine (DA), and metabolites (HVA, DOPAC) measured by the HPLC/EC method were found in SA with a parallel increase of ammonia at variance with the FC where no monoamine changes, but a slight increase of ammonia, were found. Blood ammonia did not change with HBO. So, 20 min after one HBO seizure, there are regional differences in the brain, which are consistent with the previous findings of an SA start of electrocortical abnormalities at the onset of a seizure. Elevated DA, and possibly NE, levels may contribute to the accumulation of ammonia in the brain. During prolonged HBO exposure, this rise of ammonia could be one of the mechanisms involved in the relapse of seizures. It might also be implicated in initiation of the first seizure. By their situations and contents, SA glial cells could play an important role in brain HBO susceptibility.

Ammonia↗

PubMed1989

Effects of long-term exposure to hydrostatic pressure per se (101 ATA) on eel metabolism.

Oxygen consumption, MO2, has been measured in yellow freshwater eels (Anguilla anguilla L.) exposed in normoxic conditions for 31 days at a hydrostatic pressure of 101 ATA (atmosphere absolute; 1 ATA = 0.1 MPa) using a high pressure water circulation system. The results (series I) show that from a maximal value observed at the end of compression, MO2 decreases exponentially with time (tau congruent to 1.4 days) then reaches a steady state (MO2 = 0.67 +/- 0.05 mmol.h-1.kg-1) at a lower level than observed at 1 ATA before compression (MO2 = 1.04 +/- 0.03 mmol.h-1.kg-1). These observations are in agreement with the hypothesis that shallow water fish are able to adapt to pressure; the possible mechanisms of this adaptation are discussed. Results from a second experimental series show that fish previously submitted to pressure for 1 month (then decompressed to 1 ATA) adjust faster to a new pressure exposure (4 days later) than fish that have never experienced pressure exposure. This observation suggests that the mechanisms triggered by long-term pressure exposure could persist, at least in part, for several days after decompression to atmospheric pressure.

Anguilla↗

PubMed1988

Effects of breathing an O2-H2 (20%-80%) mixture on the energy metabolism of the eel at 1 ATA.

The hypothesis of a specific effect of hydrogen on living organisms was investigated. Three tissues were studied: brain, muscle, and liver. Nucleotide concentrations (ATP, ADP, AMP, IMP, NAD) were determined using an HPLC method, and energy charge (EC) was calculated. These measurements were performed at atmospheric pressure for 50 or 132 h. Experiments were carried out using 15 control eels that breathed aerated water and 15 eels that breathed water saturated with oxygen (20%) and hydrogen (80%). No significant variation was found of the measured concentrations in muscle or liver, irrespective of the exposure duration to H2. In contrast, hydrogen induced in brain tissue a significant increase of AMP (p less than 0.005) and significant decreases of ATP (p less than 0.005) and EC (p less than 0.001). It should be noted that the EC decrease is already significant (p less than 0.05) after 50 h of exposure to H2. These modifications in energetic nucleotides were coupled with a small decrease of NAD (NS) in the three tissues explored. From the present results, obtained from eels at atmospheric pressure, it appeared that hydrogen could induce a perturbation of energy metabolism at the brain level. Its origin could be a partial saturation of respiratory chain carriers with exogen H2.

Adenosine Monophosphate↗

PubMed1988

A study of barosensitivity in the European eel (Anguilla anguilla, L.): effects of arterial pressure changes on heart rate and ventilation.

A study of the effects of arterial pressure changes on heart rate and ventilation was carried out on the eel (Anguilla anguilla L.). The anatomical characteristics of this fish enabled extracorporeal circulation in both the ventral and dorsal aorta to be set up. The pressure was changed mechanically, either by clamping external circulations or, in some cases, by modifying the frequency of a pulsatory pump placed in series with the heart, thus ensuring constant blood flows in the ventral aorta. The maximal pressure decreases obtained by clamping the external ventral aorta circulation (70%-80%) failed to induce significant changes in either heart rate or ventilation. An increase of arterial pressure up to about 50% of the control values did not induce bradycardia and ventilatory response. In the range of 50%-100% increase, a weak decrease of heart rate and slight hyperventilation were observed. Such a ventilatory response was contrary to the hypoventilation classically reported in mammals when systemic arterial pressure was increased, but similar to the hyperventilation observed when blood pressure was increased in the pulmonary arteries. The results emphasized functional analogies in regulation, originating from the circulatory bed, between the two highly compliant circulatory systems: fish circulation and pulmonary circulation of mammals.

Anguilla↗

PubMed1987

Effects of hydrostatic pressure per se (101 ATA) on energetic processes in fish.

Nucleotides concentrations (ATP, ADP, AMP) have been measured in brain and muscle of eels exposed to 101 ATA of hydrostatic pressure (HP) for 3 hr. Survival times (ST) and oxygen arterial content (CaO2) have been measured in trouts exposed to HP = 101 ATA. The results show that at HP = 101 ATA, AMP increases (P less than 0.05) and ATP decreases (-12%; NS) in muscle but are not modified in brain; ST values are similar in normoxic and hyperoxic conditions, and CaO2 are similar at 1 ATA and 101 ATA of HP. It is concluded that HP tends to decrease aerobic production of energy. This phenomenon is not due to a failure in O2 transport from ambient medium to the cell but to a possible perturbation of the aerobic cellular processes leading to energy production (Krebs cycle and/or respiratory chain coupled to oxidative phosphorylation.

Adenine Nucleotides↗

PubMed1987

[Cardiovascular effects of salbutamol in rabbits anesthetized with sodium pentobarbital].

1) Heart rate, instantaneous carotid blood flow (electromagnetic probe) and arterial blood pressure were recorded for 60 minutes in rabbits anesthetized with sodium pentobarbital (40 mg/kg). Anesthetic induction was made one hour before starting the measurements to allow animal preparation. These measurements were performed on three experimental groups--(A) group: anesthetized animals without any treatment (control group); (A + SA) group: anesthetized animals + intravenous (I.V.) infusion of salbutamol (300 micrograms/kg); (A + SE) group : anesthetized animal + I.V. infusion of a saline solution in the same volume and time conditions than for (A + SA) group, that is to say (10 ml within 10 min): this series was conducted to explore the specific effects of hypervolemia. 2) Comparing the SE and SA groups, it appeared, within 30 to 120 seconds, that I.V. infusion of salbutamol induced a decrease in systolic and diastolic blood pressures and a significant increase in heart rate and carotid blood flow. While heart rate and blood pressures returned progressively to their control values (A group), carotid blood flow was still higher 60 minutes after starting salbutamol infusion. 3) The possible mechanisms involved in the observed cardiovascular responses to salbutamol are discussed. The predominant effect is probably the hypotension resulting from a peripheral vasodilatation by direct stimulation of beta 2-adrenergic receptors in vascular smooth muscle. The increase in heart rate and carotid blood flow may be explained by a two fold mechanisms: direct stimulation of the beta-adrenergic receptors (beta 1 and/or beta 2) and consequences of the vasodilatation.

Albuterol↗

PubMed1987

[Tracheal stenosis following direct laryngoscopy].

The appearance of progressive and disabling dyspnoea in a 58 year old lady, beginning three months after direct laryngoscopy (LD) led to a pulmonary function assessment after six months of mistaken diagnoses. The flow/volume (V/V) curves were characteristic of a high fixed obstruction. Fibreoptic endoscopy showed a non-neoplastic stenosis by a sub-glottic diaphragm. The stenosis was treated in a lasting fashion using a Yag laser (Medilas 2). Other than a congenital stenosis presenting in adulthood, the only cause that can be considered is a traumatic stenosis (post-LD) on an inflamed larynx. Such an aetiology for tracheal stenosis has never, to our knowledge, been described. Even if this type of stenosis is extremely rare, the possibility should not be ignored.

Airway Obstruction↗

PubMed1985

Effects of high hydrostatic pressure per se, 101 atm on eel metabolism.

Oxygen consumption (MO2) of confined eels was measured at atmospheric pressure, 1 atm, and at 101 atm of hydrostatic pressure per se (HP). The tolerance of the eels to hypoxia was studied at the two experimental pressures. At atmospheric pressure, when oxygen partial pressure (PWO2) fell below the critical pressure, Pc = 22.4 +/- 1.95 Torr, there was a linear PWO2-related decrease in MO2. At maximal hypoxia, the eels survived for several hours by their efficient anaerobic metabolism. At 101 atm of HP, as soon as the experimental pressure was attained, a linear PWO2-related decrease in MO2 was observed at PWO2 levels much higher than those considered as critical at atmospheric pressure. The relation MO2 = f (PWO2) was similar to that observed at 1 atm when PWO2 less than Pc, that is, when aerobic metabolism was insufficient to ensure the eels' energetic requirement. Moreover, the eels tolerated hypoxia much less well at 101 atm of HP than at 1 atm. In conclusion, the exposure of eels to 101 atm of HP induced a sharp decrease in aerobic metabolism; then, at 101 atm, the energetic requirements must be ensured by anaerobic processes which produced lactates in plasma whose values were similar to those observed at 1 atm when PWO2 less than Pc.

Anaerobiosis↗

PubMed1985

Hydrostatic pressure and adrenergic drugs (agonists and antagonists): effects and interactions in fish.

Cardiac responses to alpha and beta adrenergic drugs have been studied in the eel firstly at atmospheric pressure (1 ATA), secondly at 101 ATA per se hydrostatic pressure. The exposure of treated eels for 1 hr at 101 ATA cancels the propranolol effect, increases the clonidine effect and induces paradoxal effects (reversal effect) of isoproterenol, phentolamine and phenylephrine. The highly significant interaction (P less than 0.001) between drugs and HP at 101 ATA is discussed and interpreted as effects of hydrostatic pressure inducing a change in receptor function.

Animals↗

PubMed1984

Effects of 5-HT serotonin on spontaneous locomotor activity of eels.

The swimming activity of eels maintained in tap water at 8-12 degrees C is significantly decreased after i.p. para-chlorophenylalanine (pCPA) administration at dose of 200 mg/kg (p less than 0.005 to respective control value). 5-Hydroxytryptophan (5-HTP) restored transitory swimming activity of eels. These results suggest that 5-HT has an important part in locomotor activity of eels.

5-Hydroxytryptophan↗

PubMed1984

Ventilatory and occlusion pressure responses to hypercapnia in patients with chronic renal failure.

Little is known of the effect of chronic renal failure (CRF) on ventilatory regulation. In 38 subjects (19 healthy, 19 with CRF before and after dialysis), we performed measurements of ventilation (VE) and occlusion pressure (P0.1) while the subjects were breathing air and hypercapnic gas mixtures. The results have shown that (1) during air ventilation, CRF patients exhibited lower values of VE and P0.1, which returned to normal after dialysis; (2) during hypercapnic ventilation, CRF patients had the same response as healthy subjects for VE but higher P0.1; hemodialysis induced an upward shift of the CO2 response curve in CRF patients. A twofold mechanism is probably involved: pulmonary edema, which reduces lung elasticity, and neuromuscular hypoexcitability, both implying a stronger central command.

Adult↗

PubMed1984

Effects of high hydrostatic pressure on catecholamine contents in tissues of the eel acclimatized at two temperatures.

Catecholamines (CA) are involved in many adaptative mechanisms of an organism to its environment. In fish, pressure is an environmental factor able to modify these mechanisms of adaptation, and some of the physiological perturbations observed under pressure can be compared to CA unloading. Moreover, the metabolic rate, and probably the CA metabolism of fish, are modified by the ambient temperature. This study has been conducted to measure tissue (brain and heart) CA contents (dopamine, norepinephrine, epinephrine) of eels acclimatized for 15 d at two temperatures, Tw, (15 degrees C or 25 degrees C). The measurements have been made either at atmospheric pressure (1 ATA) or after 60 min at 101 ATA of hydrostatic pressure "per se." The results show that 1) at a given Tw, pressure has no significant effect on tissue CA contents; and 2) there seems to exist a pressure-temperature antagonism concerning dopamine and epinephrine in the brain. It is suggested that this antagonism acts on enzymatic systems involved in the metabolism of these two amines.

Acclimatization↗