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Biomedical subjects

A Frans

Publications and source records attributed to A Frans.

At least 55 records · Page 3Linked to original sources
PubMed1991

Disappearance of molsidomine effects on pulmonary circulation of patients with chronic obstructive pulmonary disease after a three week treatment.

The effect of oral molsidomine (M) on the pulmonary artery hypertension of patients with chronic obstructive pulmonary disease (COPD) was investigated during an acute study (4 mg once) and after a 3 week-treatment (3 times 4 mg a day), on a double-blind basis in 16 patients, 8 receiving a placebo, and 8 molsidomine. Ventilatory and cardiocirculatory indices were obtained at rest and during exercise. When acutely given, molsidomine reduces the mean pulmonary arterial pressure (PAP), the pulmonary vascular resistance (PVR) and the arterial O2 partial pressure (PaO2), increasing heart rate (HR) as well as the alveo-arterial O2 partial pressure difference (P(A-a)O2). During exercise, pulmonary arterial pressure and pulmonary vascular resistance decrease while heart rate increases without modification of arterial blood gases. After a 3-week treatment, molsidomine no more improves any index but significantly reduces cardiac output during exercise and consequently the O2 delivery to the tissues. The same feature has already been observed for other nitrates. It thus seems inappropriate to prescribe nitrates or nitrate-like drugs to chronic obstructive pulmonary disease patients with a view to lower their pulmonary hypertension.

Blood Gas Analysis↗
PubMed1990

Aspirin--relieved asthma.

It is widely known that there might occur three different responses to the administration of ASA or NSAID to patients with bronchial asthma-bronchoconstriction, bronchodilatation or lack of bronchopulmonary action. Nevertheless, the beneficial effect of SAID has been confirmed in patients who are both nonallergic and cortico-dependent asthmatics. Our hypothesis is that in these specific cases the arachidonic acid metabolism is diverted towards cyclo-oxygenase products and that this metabolic diversion leads to an increased production of bronchoconstriction prostaglandins. The administration of NSAID inhibits the cyclo-oxygenase suppressing the enhanced basal production of these bronchoconstrictors and relieving the bronchospasm. The suspected abnormality in arachidonic acid metabolism would be restricted to the respiratory system.

Arachidonic Acid↗
PubMed1990

Paradoxical evolution of arterial blood gases during exercise in patients with chronic obstructive bronchitis.

In more than a thousand chronic obstructive lung disease (COLD) patients we have observed in six cases, that exercise-induced hypercapnia was accompanied by a concomitant improvement in arterial oxygen tension (PaO2) and a decrease in the alveolo-arterial O2. This behaviour was not due to technical errors. We explained the increase in PaO2 during exercise by three nonmutually exclusive mechanisms: 1) an increase in the respiratory quotient; 2) the exercise induced increase in alveolar ventilation, although inadequate to match the increase in CO2 production, would be redistributed to previously poorly ventilated regions of the lung, these regions therefore receiving enough oxygen to arterialize the blood flowing through the alveolar capillaries; 3) alternatively, perfusion would be redistributed in a more efficient way during exercise, so that even in the presence of hypoventilation, oxygenation would be improved.

Aged↗
PubMed1989

Effect of phosphate on oxygen-hemoglobin affinity, diphosphoglycerate and blood gases during recovery from diabetic ketoacidosis.

The effects of intravenous phosphate administration on the hemoglobin-oxygen affinity, the 2,3 diphosphoglycerate level and blood gases were investigated in twenty severe diabetic patients with ketoacidosis in the intensive care unit. Ten received phosphate (mean total amount for each patient = 300 mEq) and the others did not. The only significant difference noted in all indices measured during the recovery period of eight days was seen to occur after 48 h; the P50 in vivo (Torr) was slightly higher in the group who received phosphate (22.5 +/- 1.6 vs 20.5 +/- 2.2) and for the Hill coefficient (2.4 +/- 0.2 vs 2.2 +/- 0.1). This drop in the oxygen affinity of hemoglobin may be useful in subjects at risk of hypoxia, for example those with cardiac or respiratory failure and justifies the use of phosphate in the first 48 h of treatment of patients with diabetic ketoacidosis.

Adult↗
PubMed1989

Effects of two inotropic drugs, dopamine and dobutamine, on pulmonary gas exchange in artificially ventilated patients.

The inotropic agents, dopamine (DP) and dobutamine (DB), both decrease PaO2, probably by a redistribution of the VA/Q ratio. The aim of this study was to assess the effect of both drugs on the VA/Q ratio, using the multiple inert gas elimination method. Ten artificially ventilated patients (eight males), aged 45-74 years were investigated. Blood gases, cardiac output and concentrations of inert gases were measured before and 30 min after infusion of DB or DP. DP and DB were administered alternatively at a rate of 5 micrograms.k-1 min-1. The decrease in PaO2 was significantly greater with DP (12 +/- 9 torr) than with DB (7 +/- 9 torr) (P less than 0.01). Both drugs similarly increased cardiac output: +2.61.min-1 +/- 1.4 for DP and 2.21.min-1 +/- 1.5 for DB. Both DP and DB significantly (P less than 0.01) increased the perfusion of alveoli with VA/Q = 0 (+4 +/- 7% for DP and +3 +/- 7% for DB) and 0 less than VA/Q less than 0.1 (+11 +/- 8.5% for DP and +5.5 +/- 10.5% for DB) (no significant difference between the drugs). When shunt and "shunt-like" effect are considered together, there was a significantly greater increase in the amount of blood going to alveoli with a low VA/Q ratio with DP compared to DB. Both drugs decreased the perfusion of alveoli with 0.1 less than VA/Q less than 10, but the decrease was significantly less for DB than for DP (-15 +/- 6.5% for DP and -8.5 +/- 7% for DB, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Cough as the sole manifestation of airway hyperreactivity.

The authors report 18 patients who presented to the ENT department with isolated cough, which had begun one month to 14 years previously. As the ENT examination was negative, the patients were referred to the Department of General Medicine where a bronchial reactivity test with acetylcholine was found to be positive, leading to a diagnosis of airway hyperreactivity. The group was predominantly female (15/18) and atopy was rare; indeed, only one patient, who had a history of allergic rhinitis, was found to be atopic. Bronchodilators and inhaled steroids cured or helped the cough in 16/18 patients. When a patient presents with chronic cough without other respiratory symptoms it is important to consider a diagnosis of airway hyperreactivity and to confirm this with a challenge test of bronchoconstriction.

Adolescent↗
PubMed1989

Pulmonary gas exchange during graded exercise in normal, sedentary, non-smoking subjects.

There is some discordance in the literature on the evolution of the alveolo-arterial oxygen tension difference (A-a)DO2 from rest (R) to graded exercise (E) in healthy subjects. For some authors and not for others (A-a)DO2 increased during exercise. In order to solve this problem we have examined 9 healthy, non-smoking sedentary students (5 males). In every subject PaO2 increased from rest to the highest level of exercise. (A-a)DO2 significantly increased from R and E1 to E2 and from E3 to E4. (A-a)DO2 at rest was 7.5 +/- 4.1 torr; at E1: 7.0 +/- 4.3 torr; at E2: 11.5 +/- 4.2 torr; at E3: 12.5 +/- 3.9 torr; and at E4: 16.5 +/- 4.3 torr. The oxyhemoglobin dissociation curve (ODC) was significantly shifted to the right from 53 to 92% saturation. This shift favours the liberation of O2 from hemoglobin to the tissues but cannot explain the evolution of (A-a)DO2. We believe that the increase in (A-a)DO2 is due to an increased maldistribution of the ventilation-perfusion ratio.

Adult↗
PubMed1989

Acute effect of molsidomine on pulmonary circulation of patients with chronic obstructive pulmonary disease.

Chronic obstructive lung diseases (COLD) are very often complicated by pulmonary arterial hypertension and right heart failure. Several drugs including nitrates have been used to counteract this type of hypertension. Molsidomine (M) is a recent nitrates-like drug acting for a longer time than the classical nitrates. Our aim was to investigate whether M could significantly lower pulmonary arterial hypertension of patients suffering from COLD. Ten male patients were investigated before and after intake of 4.0 mg M given sublingually. Ventilatory and cardiocirculatory indices were measured at rest and during a 30 and a 50 watts exercise. During exercise, M significantly lowers pulmonary arterial pressure and pulmonary vascular resistance without detrimental effect on arterial blood gases. M seems to be a promising drug to counteract the pulmonary hypertension of patients with COLD.

Heart Failure↗
PubMed1989

[Asthma relieved by aspirin].

Some particular cases of bronchial asthma are improved by acetylsalicylic acid. The clinical characteristics of these patients are very similar to those of asthmatic ASA-sensitive cases: a cortico-dependent asthma occurring in later life, in nonatopic patients with chronic rhinitis, sinusitis and/or nasal polyposis. The patient notices that taking an occasional aspirin tablet for some other problem reduces his respiratory symptoms. The bronchodilator effect of aspirin and other Non Steroidal Anti-Inflammatory Drugs in such patients has been clearly demonstrated, although all drugs don't have the same effectiveness. It is important to diagnose these aspirin-relieved asthma cases, using an oral aspirin test, because the treatment with aspirin allows us then to reduce the needed corticosteroid dose. We hypothesize that a diversion of the arachidonic acid metabolism towards cyclo-oxygenase products causes this syndrome.

Arachidonic Acids↗
PubMed1988

Oxygen transport properties of blood in two different bovine breeds.

1. The whole oxygen dissociation curve of oxyhemoglobin has been determined in double-muscled cattle of the Belgian White Blue breed and in Friesian cattle of different body weight. 2. In calves, P50 values are low and DPG level is high (4-20 mumol/g Hb). 3. P50 values of 25 +/- 1.4 mm Hg (mean +/- SD) and a level of DPG less than 1.5 mumol/g Hb have been found in animals weighing more than 80 kg. 4. Effects of temperature and pH on the oxygen dissociation curve have been measured at all levels of saturation. The temperature coefficient (dlog P50/dT) and the Bohr effect expressed as dlog P50/dpH were 0.017 and -0.40, respectively. 5. Hematocrit, hemoglobin concentrations and oxygen capacity of hemoglobin have been measured. 6. No difference between both breeds has been observed. 7. These data can be used to correct measured values of oxygen tension for temperature and pH and to measure oxygen content of blood in cattle.

Animals↗
PubMed1988

Effect of molsidomine on the lung diffusing capacity of normal men.

Molsidomine (M) is a new antianginal drug which induces a peripheral venous pooling and decreases pulmonary artery and pulmonary venous pressures. The purpose of our study is to assess whether M influences the filling of the pulmonary capillary bed as estimated by the single-breath lung diffusing capacity (DLCO). DLCO was measured before and 10, 20, 30, 40, 50 and 60 minutes after sublingual administration of 2 mg molsidomine in six healthy men examined in sitting and supine positions. The blood flow distribution was estimated by means of radioactive xenon, in sitting position only, before and 30 minutes after M intake. M. induces a significant fall in DLCO from the 20th to the 60th minute which indicates an emptying of the pulmonary capillary bed. Concomitantly, blood flow is redistributed from the apices to the lung bases. We explain the decrease in DLCO by two mutually non-exclusive mechanisms: an outflow of the blood from the thorax to the periphery and a change in the lung-perfusion distribution. From a practical point of view, two conclusions may be reached. First, in coronary patients a decrease in DLCO and DLCO/VA may be due to the intake of vasodilating agents such as molsidomine and not to emphysema or lung fibrosis. Secondly, the measurement of DLCO is a useful tool to assess the action of a drug on the pulmonary circulation.

Adult↗
PubMed1987

Impairment of ventilatory function and pulmonary gas exchange in non-smoking coalminers.

Indices of ventilatory function and pulmonary gas exchange in 32 non-smoking coalminers (mean age 38.1) were compared with those of 34 non-smoking steelworkers of similar age. The coalminers had significantly lower forced expiratory volume in 1 s (FEV1) and maximum expiratory flow rates and significantly higher residual volume, but similar vital capacity and indices derived from the single-breath test. Pulmonary diffusing capacity for CO and indices of CO2 exchange were similar in both groups. Arterial partial pressure of O2 (PaO2) was significantly lower and alveolar-arterial O2 difference was significantly higher in coalminers than in controls, both at rest and during exercise. There was no relation between lung function and radiological signs of simple pneumoconiosis (10 coalminers had pneumoconiosis). The differences in FEV1 (0.42 l) and in PaO2 (10 mm Hg) between the two groups are the same or larger than those usually found between smokers and non-smokers. Exposure to coaldust may result in biologically significant alterations of lung function even in the absence of pneumoconiosis.

Adult↗
PubMed1986

Hysteresis of the alveolar capillary membrane in normal subjects.

Weibel and associates (Respir. Physiol. 18: 285-308, 1973), using morphometric techniques, demonstrated in the rat that changes in lung volume related to inflation and deflation caused a hysteretic variation in alveolar capillary membrane which is locally pleated at low pulmonary volume, unfolds during inflation but does not immediately refold during deflation, possibly enhancing the CO diffusion throughout the membrane. The present study was conducted to verify the existence of this hysteresis in human lungs in vivo. Single-breath diffusing capacity for CO (DLCO) was measured in five healthy seated subjects before and 0, 0.5, 1, 3, and 7 min after an inflation-deflation maneuver (IDM) in 6 separate days. The value of mean DLCO was 36.4 +/- 3 (SD) before and 42.1 +/- 2.9, 41.6 +/- 3.3, 40.3 +/- 3.3, 39.2 +/- 3.2, and 38.1 +/- 2.7 ml X min-1 X Torr-1 after the IDM. Two mechanisms can explain our findings: an active filling of the capillary bed, or an unfolding of the alveolar capillary membrane. The first mechanism should be accompanied by changes in pulmonary circulation. Therefore, right-heart catheterization was performed in two normal subjects and in four patients examined for a chest pain syndrome. At the end of the IDM, the values for the pulmonary artery pressure and capillary wedge pressure had returned to control levels. This suggests that the capillary bed is not directly involved in the DLCO increase observed from 0.5 to 7 min after the IDM. The unfolding of the alveolar capillary membrane appears to better explain our findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Volume↗