Search PubMed⌕ Search

Biomedical subjects

A Frans

Publications and source records attributed to A Frans.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Effect of almitrine administered by the oral route on levels of 2,3-diphosphoglycerate and on the affinity of hemoglobin for oxygen in healthy subjects].

Clinical and pharmacological studies have shown that almitrine increased arterial blood oxygen partial pressure (PaO2) and tissular oxygenation. We have verified whether this drug could also increase the 2,3 diphosphoglycerate (DPG) level and so modify the oxyhemoglobin dissociation curve (ODC). Determinations performed 3 hours and 5 days after daily oral administration (1,5 mg/kg) of the drug showed no alterations of DPG and ODC in normal subjects. The presence of almitrine does not explain the observed PaO2 increase by means of a direct effect on the hemoglobin oxygen affinity. However, one cannot exclude almitrine long term effect; indeed, after 15 days, DPG levels and Hill coefficient increased significantly (p less than 0.05) but no the P50 (respectively + 1,5 mumole/gHb; +0.1 and 26.0 vs 26.5 mmHg).

2,3-Diphosphoglycerate↗
PubMed1983

Effects of gas density on pulmonary gas exchange of normal man at rest and during exercise.

Changes in the physical properties of inspired gas might be expected to influence the distribution of ventilation in the lungs as well as the diffusive and convective (cardiogenic) mixing of inspired gas with lung residual gas, thus possibly affecting pulmonary gas exchange for O2 and CO2. The purpose of our work was to assess to what extent this occurs in practise in human subjects, who could compensate for the changes directly brought about by altering the physical characteristics of the inhaled gas by changing their breathing pattern. Six healthy, non-smoking men breathed, at rest and during moderate exercise, gas mixtures containing 21% oxygen completed either by 79% nitrogen (air), helium (O2-He) or sulphur hexafluoride (O2-SF6). We observed that the inhalation of these three different gas mixtures whilst at rest did not affect arterial partial pressures of O2 or CO2, the physiological dead space to tidal volume ratio, or the alveolo-aADCO2). During exercise, AaDO2 was slightly (2-3 mm Hg) but significantly higher with both O2-He and O2-SF6 than with air. Although minute ventilation did not change, breathing frequency was slightly but significantly affected by the type of gas mixture breathed, being lower with O2-SF6 and higher with O2-He. We conclude that, within the range studied, the physical properties of the inhaled gas do not affect pulmonary gas exchange in healthy man, either because the changes affected are minimal or because they compensate for each other.

Adult↗
PubMed1983

Pulmonary vascular tone is a determinant of basal lung perfusion in normal seated subjects.

In the human upright lung the downward increase in lung perfusion reverses in the lower third, thus giving rise to a zone of reduced basal perfusion (zone 4). The flow in zone 4 is regulated by the extra-alveolar vessels, the diameter of which is determined by lung volume, perivascular interstitial pressure, and vasomotor tone. To estimate the role of pulmonary vascular tone in the formation of zone 4, we infused nitroprusside (NTP), a potent pulmonary vasodilator, in six normal seated subjects. We measured their regional perfusion distribution using 133Xe in control conditions and at two dose levels of NTP (20.8 and 52.1 micrograms/min). Regional perfusion distribution was measured similarly and according to the same protocol in six subjects receiving only a placebo solution. In four of the six subjects receiving NTP, right-heart catheterization allowed simultaneous estimations of cardiac output and pulmonary arterial pressure to be made. NTP slightly decreased the perfusion of the nondependent parts of the lungs and markedly increased the perfusion of the lung bases, thus reducing the extent of zone 4. No changes were observed in the placebo experiments. Cardiac output and indices of ventilation and gas exchange did not change significantly. Peripheral and pulmonary arterial pressure fell slightly but significantly during NTP infusion. We attribute the observed changes in basal perfusion to the vasodilatory effects of NTP on the extra-alveolar vessels. Our findings thus support the hypothesis that in normal subjects zone 4 is partly created by the pulmonary vascular tone.

Adult↗
PubMed1982

Effect of age on the regional perfusion and washouts of injected xenon in normal men.

The aim of this work was to localize the alveoli with low ventilation-perfusion ratio which are responsible for the age related increase of the ideal alveolar-arterial O2 partial pressure difference. For this purpose, we measured: (1) the washouts of perfused 133 Xenon (Xe) in the whole lung and in 6 horizontal slices of the right lung, and (2) the topographical distribution of perfusion (Qi) in 27 healthy, non-smoking seated men, between 18 and 65 years. The distribution of Qi is unaffected by age. The global and regional washouts slowed with age, the trends being the same in the 6 investigated regions. This data was interpreted as indicating that in our subjects the low VA/Q units are not situated predominantly at the base, but are scattered throughout the lung.

Adult↗
PubMed1982

Effect of nitroglycerin on pulmonary perfusion distribution and gas exchange of normal subjects.

In eight healthy subjects we assessed the effects of 3 mg sublingual nitroglycerin on lung distribution of ventilation and perfusion using 133Xe (sitting, supine and lateral decubitus) and on alveolo-arterial O2 and CO2 partial pressure differences [(PAO2-PaO2), (PaCO2-PACO2)] and physiological dead space to tidal volume ratio (VD/VT) (sitting). In all studied positions, nitroglycerin induced a significant decrease in uppermost perfusion indices, and a significant increase in dependent perfusion indices, without changing the distribution of ventilation. Significant increases in (PaCO2-PACO2) and VD/VT were observed up to 60 min after nitroglycerin. No changes in (PAO2-PaO2) occurred, except for a transient decrease due to transient hyperventilation following nitroglycerin. The redistribution of pulmonary perfusion after nitroglycerin may be attributed to the passive effects of lowered pulmonary vascular pressures, and to possible action on extra-alveolar vessels. The evolution of the indices of pulmonary gas exchange is compatible with the observed redistribution of ventilation/perfusion relationships.

Adult↗
PubMed1982

Effect of nitroglycerin on DL of normal subjects at rest and during exercise.

By use of the single-breath diffusing capacity for carbon monoxide (DL) as an index of the pulmonary capillary filling, the effects of 3 mg sublingual nitroglycerin (NTG) were studied in eight healthy subjects at rest and during exercise. At rest, NTG induced a significant and persistent decrease of DL when subjects were sitting or supine (60 min of observation) and also when they were in the lateral decubitus or supine with legs up position (30 min of observation). Subjects in the supine positions showed more pronounced percentage decreases in DL than when sitting. In the sitting position 1 mg NTG also induces a decrease of DL. During a moderate upright cycloergometer exercise, NTG also induces a significant decrease of DL; the decrease is smaller and of shorter duration (less than 15 min) than at rest, but it reappears as soon as the exercise is stopped. The decrease of DL may be attributed to an outward shift of blood from the thorax to the periphery or to a redistribution of lung perfusion consequent to changes in pulmonary vascular pressures.

Adult↗
PubMed1982

Bronchial asthma without increased airway reactivity.

We have observed nine asthmatic patients with less than 10% decrease in 1s forced expiratory volume (FEV1) after inhaling acetylcholine. Four of these patients with "intrinsic" asthma were studied before, during and after a spontaneously occurring asthmatic episode. FEV1 was significantly less (P less than 0.02) during airway obstruction than before and after recovery. The average decrease in FEV1 after inhalation of acetylcholine, before and after the obstructive episode, was 5%. In one patient, acetylcholine inhaled during the obstructive episode was followed by only 1% changes in FEV1. Histamine aerosols, administered either before or after the obstructive episode, induced an average drop in FEV1 of 4.7%. A fifth patient with "extrinsic asthma" had a 27% decrease in vital capacity following acetylcholine, during the exposure period to natural allergens, but less than 6% drop in FEV1 outside season when asymptomatic. The average diminution in FEV1 after histamine and acetylcholine was less than 3% in 13 healthy subjects, while in 14 consecutive asthmatics it averaged 40%. We conclude that airway hyperreactivity is not a constant feature in bronchial asthma.

Acetylcholine↗
PubMed1979

Effect of variations in blood hydrogen ion concentration on pulmonary gas exchange of artificially ventilated dogs.

The effect of variation of blood hydrogen ion concentration on arterial and mixed venous PO2, ideal alveolar-arterial O2 pressure difference (PAiO2--PaO2), venous admixture (Qs/Qt), arterio-alveolar CO2 pressure difference (a--A)DCO2, physiological dead space to tidal volume ratio (VD/VT), cardiac output (Qt) and mean pulmonary arterial pressure (PAP) has been studied. Arterial and mixed venous PO2 increased and (PAiO2--PaO2) decreased with increasing blood hydrogen ion concentration. No change in Qs/Qt, (a--A)DCO2, VD/VT, Qt and PAP was observed. The effect of hydrogen ion concentration on arterial and mixed venous PO2 and on (PAiO2--PaO2) is mainly due to a shift of the blood oxyhemoglobin dissociation curve (ODC), i.e. due to the Bohr effect. The upper part of the ODC is more flat in alkalosis (shift to the left) than in acidosis (shift to the right). Therefore the same end-capillary to arterial O2 content difference results in a greater (PAiO2--PaO2) in alkalosis than in acidosis. Any factor influencing the slope of the upper part of the ODC is expected to affect the arterial PO2 and the (PAiO2--PaO2) by this mechanism. Similarly any factor shifting the steep part of the ODC is expected to affect the PO2 of the mixed venous blood.

Animals↗
PubMed1976

Evaluation of lung function indices for bronchodilator trials. Results of a cross-over study of fenoterol.

In 10 patients with airway obstruction, spirographic indices and maximal expiratory flow rates were measured before inhalation of fenoterol and at different time intervals, for 5 h, following the inhalation of 200 mug of this substance. 10 min after inhalation of fenoterol, there was a statistically significant increase in all lung function indices. A further increase was observed later. 3 h after inhalation of fenoterol, all indices were still significantly higher than control values. No side effects were observed. At all time intervals, the increase of the forced expiratory volume in 1 sec (FEV1.0), peak expiratory flow rate (PEFR) and maximal expiratory flow rate at 50 and 75% of the vital capacity reached a similar level of statistical significance. It is concluded that for the trial of the bronchodilator drugs, any of these indices may be used, and for practical purposes FEV1.0 and PEFR are best suited.

Adult↗
PubMed1976

Hemodynamic effects of lidoflazine during graded levels of bicycle exercise in normal subjects.

The hemodynamic effects of lidoflazine were studied in 12 young healthy subjects who received the drug orally (240 mg daily) for 8 weeks. During exercise after lidoflazine, heart rate (-2.6%), mean arterial pressure (-3.1%), arterio-venous oxygen (A-V02) difference (-3.4%), pressure rate product (-6.2%), and systemic vascular resistance (-8.6%) were significantly lower, while cardiac output (+5.4%) and stroke volume (+8.3%) were significantly greater. The maximal heart rate was lower after lidoflazine (-6 beats/min) but the maximal oxygen intake (VO2max) was not affected by the drug. The major hemodynamic effects of lidoflazine appear to be, on the one hand, an unexplained decrease in heart rate, and on the other, a decrease in systemic vascular resistance; the latter, which was expected from a vasodilator, could account for the greater stroke volume and contributes to the decrease of the pressure rate product. Lidoflazine has another unexplained effect, i.e. a decrease of the A-VO2 difference, suggesting a decreased peripheral extraction of oxygen at rest as well as during submaximal and maximal exercise.

Adult↗
PubMed1975

Smoking and pulmonary diffusing capacity.

The pulmonary diffusing capacity (DLCO SB) and its two components, the capillary blood volume (Vc) and the diffusing capacity of the membrane (DMCO), expressed in absolute values and per litre of alveolar volume (VA'), were measured at rest and on exercise in healthy male smokers and nonsmokers of similar age and height, and with identical values for haemoglobin and spirographic data. DLCO, DLCO/VA', DMCO and DMCO/VA' are significantly lower in smokers, at rest and on exercise; the decrease in Vc and thetaVc/VA' in smokers at rest is due to a higher level of carboxyhaemoglobin. The decrease of DLCO, DLCO/VA', DMCO and DMCO/VA' is apparently not due to carboxyhaemoglobin or distributional factors but to anatomical lesions, probably of emphysematous nature, altering the pulmonary membrane. Formulas predicting DLCO, DMCO, Vc, DLCO/VA', DMCO/VA' and thetaVc/VA' in terms of age and height were established in smokers and in nonsmokers.

Adult↗