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Biomedical subjects

J F Costello

Publications and source records attributed to J F Costello.

90 records · Page 5Linked to original sources
PubMed1983

Effects of nifedipine on antigen-induced bronchoconstriction.

We have investigated the effects of the calcium antagonist nifedipine on antigen-induced bronchoconstriction in vivo and in vitro. Eight grass-pollen-sensitive asthmatics were given either nifedipine (20 mg sublingually) or placebo 30 min before antigen challenge. The fall in forced expiratory volume in one second after pretreatment with placebo was 42.8 +/- 10.1%. After nifedipine this fall was significantly reduced to 26.5 +/- 11.7% (p less than 0.005). Two in vitro models of allergic asthma have been studied: actively sensitized guinea pig tracheal strips (GPT) and passively sensitized human bronchial muscle (HBM). Contraction of GPT by acetylcholine, histamine, and antigen challenge was unaffected by nifedipine 10(-4)M. Contraction of HBM by acetylcholine, histamine and grass pollen antigen challenge was significantly reduced by nifedipine 10(-4)M and 10(-6)M. The magnitude of the reduction in contraction to antigen challenge was comparable to the inhibition of acetylcholine and histamine responses. It would appear most likely that nifedipine exerts its effect mainly on bronchial muscle contractility rather than by stabilizing mast cells.

Adult↗
PubMed1983

Adverse effect of rifampicin administration on steroid-dependent asthma.

Induction of steroid metabolism has been reported after rifampicin administration but it is not known how much corticosteroid requirements increase and whether disease control can be satisfactorily maintained with increases in corticosteroid dosage. Because rifampicin may be needed in the treatment of tuberculosis in patients with steroid-dependent asthma, the dose of prednisolone needed to control this condition after rifampicin administration (600 mg daily for 6 wk) was determined in 6 patients in a randomized, double-blind, placebo-controlled trial. The plasma elimination half-life and bioavailability of prednisolone decreased significantly after rifampicin administration, but despite an increase of 93% in the dose of prednisolone (p less than 0.02), asthma control remained inferior compared to placebo. Asthma relapse in a seventh patient necessitated withdrawal from the trial after 2 wk of rifampicin administration despite a five-fold increase in prednisolone dosage. It is concluded that despite substantial increases in the dose of prednisolone the coadministration of rifampicin and prednisolone to steroid-dependent patients may seriously complicate their clinical management.

Adult↗
PubMed1983

Incomplete recovery of inequality of ventilation after clinical recovery from acute asthma.

Studies of lung function were carried out on 8 asthmatics during and after an acute attack. Inequality of ventilation as measured by the argon alveolar plateau (Ar(1-2] showed gradual improvement during the period of observation in most of these asthmatic subjects. Residual inequality of ventilation was detected in these subjects during clinical 'remission' when compared to values for Ar(1-2) in normal subjects (P less than 0.01). The degree of inequality of ventilation observed correlated with hypoxaemia (P less than 0.05). All subjects tested with helium-oxygen flow-volume curves were initially 'non-responders', but 7 out of 8 became responders during their clinical recovery. This suggests that the main site of airflow obstruction may be in the peripheral airways in acute severe asthma but that this improves during clinical recovery and then the main site of airflow limitation switches to the larger airways. The mean respiratory exchange ratio difference between one and two litres of expiration R(1-2) was raised in the first 4 days of observation (P less than 0.05) reflecting the presence of ventilation-perfusion imbalance. However no residual imbalance was detected in the mean R(1-2) after day 11.

Adult↗
PubMed1982

A comparative double-blind study of the bronchodilator effects and side effects of inhaled fenoterol and terbutaline administered in equipotent doses.

Increasing doses of fenoterol and terbutaline were administered by inhaler to 12 stable asthmatics in a double-blind crossover trial. 100 microgram doses of fenoterol were shown to be equal in potency to 250 microgram doses of terbutaline, as measured by increases in forced expiratory volume in the first second (FEV1) and specific airways conductance (sGaw). FEV1 and sGaw remained significantly greater than pretreatment levels up to five hours after both drugs and terbutaline showed a significantly greater effect on FEV1 than fenoterol after four hours suggesting a small but significantly longer duration of activity. Fenoterol used at the dosage of 100 micrograms per puff (half the standard commercially available dose of 200 micrograms per puff) caused significantly more cardiac effects than terbutaline, as measured by the magnitude and duration of increases in heart rate, and the incidence of reported palpitations.

Adolescent↗
PubMed1981

Diaphragm pacing in ventilatory failure.

Diaphragm pacing, which entails electrical stimulation to the phrenic nerve, is an effective means of managing patients with ventilatory insufficiency and intact lowermotor-neurone innervation of the diaphragm. The pacing apparatus is used to pace the right and left hemidiaphragms alternately to avoid fatigue, which may damage the muscle irreversibly. Among the important benefits of pacing in quadriplegics with paralysis or respiratory muscles are the social and psychological advantages of not being dependent on a mechanical ventilator.

Adult↗
PubMed1978

Changes in theophylline clearance during acute illness.

Three patients demonstrated twofold to threefold changes in total-body theophylline clearance during the course of a single hospitalization for an acute illness. These changes paralleled the changes in the patients' clinical status. Theophylline clearance decreased in one patient with worsening airway obstruction, whereas clearance increased in one patient with resolving pneumonia and in one patient with improving congestive heart failure. Total-body theophylline clearance may be unstable in acute, severe illness. Close monitoring of plasma theophylline concentration in such situations will allow appropriate dose adjustments to be made and is, therefore, indicated.

Acute Disease↗
PubMed1976

Effect of intravenous infusion of salbutamol on ventilatory response to carbon dioxide and hypoxia and on heart rate and plasma potassium in normal men.

Intravenous infusion of salbutamol 10 mug/min in seven healthy subjects significantly increased their ventilatory responses to inhaled CO2 in both hypoxia and hyperoxia. These changes in chemical control of breathing are unlikely to be significant when the drug is used in severe asthma but may benefit patients with acute exacerbations of chronic ventilatory failure. The infusion also increased heart rate, which was most pronounced when hypoxia was combined with hypercapnia. The infusion produced an average fall in plasma potassium from 3-99 to 3-10 mmol/l, which was associated with an increase in plasma glucose and serum insulin, suggesting that this arose from a shift of potassium from the extracellular to the intracellular space. Routine monitoring of plasma potassium and the electrocardiogram is indicated when an intravenous salbutamol infusion is used to treat severe asthma as the drug may predispose to cardiac dysrhythmias.

Adult↗
PubMed1975

Acute effects of smoking tobacco and a tobacco substitute on lung function in man.

The acute effects on airway function of smoking one cigarette of a tobacco substitute 'New Smoking Material' (NSM), one cigarette of conventional tobacco, and one cigarette containing 70% tobacco and 30% NSM, were studied in 6 healthy nonsmokers and 6 healthy smokers. None of the cigarettes produced any change in three tests of small-airway function (flow-volume curves, closing volume, frequency dependence of compliance). However, smoking either one conventional tobacco cigarette or the 30% NSM/70% tobacco cigarette produced an acute fall in specific airways conductance, of similar degree with both cigarettes, whereas the 100% NSM cigarette produced no such change.

Adolescent↗
PubMed1975

Diagnosis and management of alveolar proteinosis: the rôle of electron microscopy.

The diagnosis and management of three cases of pulmonary alveolar proteinosis are described. The electron microscopic appearances of lung biopsy material, lung washings, and sputum and the value of this method of sputum examination in extremely ill patients are demonstrated. The practical details of controlled volume bronchial lavage are described and the good clinical and physiological response of patients reported. The findings have been compared with those of experimental pulmonary alveolar proteinosis, and the pathogenesis of the condition is discussed.

Adult↗