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Biomedical subjects

M Gent

Publications and source records attributed to M Gent.

At least 163 records · Page 9Linked to original sources
PubMed1981

Synergism between ipratropium and theophylline in asthma.

Ipratropium bromide is a bronchodilator whose effect has been compared with beta agonists but not with theophylline. Twelve asthmatics were given four two-week courses of the different combinations of ipratropium (40 micrograms in two puffs), theophylline capsules, and their corresponding placebos in a random, double-blind fashion. There was a significant increase in FEV1 and MMFR 60 minutes after theophylline was administered (p less than 0.05) when measured after one and two weeks of therapy. FEV1 and MMFR were significantly increased (p less than 0.05) 30 and 60 minutes after ipratropium inhalation and this increase was significantly greater when the patient had also been taking theophylline compared with placebo capsules (p less than 0.05). There was no toxicity associated with this combination. The synergism demonstrated may be related to the time sequence of drug administration, mechanical or cellular factors.

Adult↗
PubMed1981

Clinical validity of a negative venogram in patients with clinically suspected venous thrombosis.

Although it is generally accepted that negative venography excludes deep vein thrombosis (DVT) in patients in whom it is clinically suspected, there is no evidence to support this conclusion. To test the correctness of withholding anticoagulant therapy in these patients, we followed 160 consecutive patients who had clinically suspected DVT and negative venograms to determine the frequency of postvenographic DVT. Anticoagulant therapy was withheld in all patients. No patient died or developed pulmonary embolism during 3 months of follow-up. Two of the 160 patients (1.3%) attended the clinic on an emergency basis during follow-up with new symptoms of DVT and in both patients, DVT was confirmed by objective testing. These events developed within 5 days of venography, which suggests that they were induced by venography. Nevertheless, the findings indicate it is safe to withhold treatment in patients with clinically suspected DVT and negative venograms.

Adolescent↗
PubMed1981

Enhanced platelet accumulation onto injured carotid arteries in rabbits after aspirin treatment.

Prostacyclin (PGI2) is a powerful inhibitor of platelet aggregation, but its role in the pathogenesis of arterial thrombosis is uncertain. We have studied the thrombogenic effect of inhibiting PGI2 production by aspirin (ASA) in carotid arteries of rabbits given 0, 3, 10, or 100 mg ASA/kg either 1, 3, 6, or 20 h beforehand. Platelet accumulation onto injured carotid arteries was enhanced with ASA in a dose of 10 mg/kg. A higher dose of ASA (100 mg/kg) had no further effect. The enhanced thrombogenic effect of ASA persisted for at least 20 h and was associated with a decrease in vessel wall PGI2 production. There was a strong inverse correlation (r = 0.55, P less than 0.01) between PGI2 production and platelet accumulation. The findings suggest that the margin of safety in obtaining an antithrombotic effect of ASA and producing a potential thrombotic effect in arteries may not be as large as predicted by studies using cultured endothelial cells or experimentally induced thrombosis in veins.

Animals↗
PubMed1981

Replacement of venography in suspected venous thrombosis by impedance plethysmography and 125I-fibrinogen leg scanning: a less invasive approach.

Noninvasive diagnostic testing is gaining acceptance in the evaluation of patients with clinically suspected venous thrombosis. Although clinically useful, all these tests have limitations, and the safety of basing therapeutic decisions on their outcome has not been assessed. We have done a prospective study of 322 symptomatic patients to ascertain the safety of replacing venography with impedance plethysmography and leg scanning. To provide a diagnostic reference, we did venography in all patients but withheld anticoagulants if the noninvasive tests were negative irrespective of the results of venography. None of the 163 patients with negative noninvasive tests died or developed clinical pulmonary embolism during 3 months' follow-up, confirming the safety of this approach. In two, clinically evident postvenographic venous thrombosis developed, confirmed by repetition of these objective tests. Also, the positive predictive values indicate that therapeutic decisions can be based on a positive noninvasive outcome in patients without clinical disorders known to produce false-positive results.

Adolescent↗
PubMed1981

The effect of ipratropium on exercise-induced bronchoconstriction.

We studied the effect of ipratropium on exercise-induced bronchoconstriction (EIB) at cold or warm temperatures. Although pulmonary function was better with ipratropium, its benefit was related to pre-exercise bronchodilation and not prevention of EIB. Ipratropium did not affect the augmented EIB in cold weather. Therefore, these phenomena are not primarily mediated via cholinergic mechanisms.

Adolescent↗
PubMed1980

Randomized trial of therapy with platelet antiaggregants for threatened stroke. 2: Observations on the pathogenesis and natural history of threatened stroke.

Transient cerebral ischemia and stroke may occur despite previous occlusion of the artery supplying the appropriate part of the brain. After occlusion of the internal carotid artery, emboli may pass from the "stump" of the occluded artery to later produce transient cerebral ischemia or a stroke. Transient cerebral ischemia and stroke are due to a variety of conditions, some of which are strongly correlated with platelet thromboembolism, while others have little primary relation to thrombosis. The impact of this on therapeutic considerations is obvious. Thromboembolism related to myxomatous degeneration of the mitral valve (mitral valve prolapse) is a factor to consider in determining the cause of a stroke in a younger person. The prognosis for the different varieties of threatened stroke is incompletely known. When due to arteriosclerosis of the large cerebral arteries, transient cerebral ischemia and minor strokes pose a cumulative threat for a major stroke or death of 13% in the first year, 22% in the second year and 30% in the third year.

Adolescent↗
PubMed1980

A randomized trial of aspirin and sulfinpyrazone in patients with threatened stroke. Results and methodologic issues.

In the Canadian Cooperative Study of aspirin and sulfinpyrazone in patients with threatened stroke, there was no demonstrable benefit of sulfinpyrazone but there was a significant overall risk reduction in stroke or death of 31% with aspirin (p less than 0.05). This benefit of aspirin was restricted to males, in whom the risk reduction in stroke or death was 48% (p less than 0.005). As with a large-scale clinical trials, questions have been raised about the methodology of the study, including the type of patient included, the choice of outcome measures, the factorial design and the analysis of subgroups. In this report, the design and principal results of the study are summarized and the above methodologic concerns are discussed.

Actuarial Analysis↗
PubMed1979

Warfarin sodium versus low-dose heparin in the long-term treatment of venous thrombosis.

Acute deep-vein thrombosis is usually treated with intravenous heparin for a number of days, then with oral anticoagulants for weeks to months. We have compared adjusted-dose warfarin sodium with fixed low-dose subcutaneous heparin in the prevention of recurrent deep-vein thrombosis. Sixty-eight patients with acute deep-vein thrombosis confirmed by venography were treated with intravenous heparin and then randomized to secondary prophylaxis. Nine of 35 patients receiving subcutaneous heparin, but none of 33 receiving warfarin sodium, had new episodes of objectively documented venous thromboembolism (P = 0.001). Seven patients on warfarin sodium experienced bleeding complications (of which four were major), as compared with no patients receiving subcutaneous heparin (P less than 0.005). Thus, adjusted-dose warfarin sodium is more effective than low-dose subcutaneous heparin in preventing recurrent venous thromboembolism, but its use is accompanied by a significant risk of bleeding.

Acute Disease↗
PubMed1979

The spectrum of ABO hemolytic disease of the newborn infant.

A series of 1,704 infants of blood group O mothers have been studied to determine the relation between the degree of red cell sensitization and the cord hemoglobin and bilirubin concentrations. The infants with blood group A or B had significantly higher cord bilirubin and lower cord hemoglobin concentrations than the group O babies. Those infants whose red cells had the greatest evidence of sensitization had the highest bilirubin and lowest hemoglobin levels. The infants in whom no antibody was demonstrable on the red cells or in the red cell eluate also had significantly higher cord bilirubin and lower cord hemoglobin levels than the ABO compatible group; it is suggested that these infants had sufficient erythrocyte sensitization to produce mild hemolysis. ABO incompatibility represents a spectrum of hemolytic disease extending from those in which there is little laboratory evidence of erythrocyte sensitization, but evidence of hemolysis, to severe hemolytic disease in which erythrocyte sensitization is usually easily demonstrable.

ABO Blood-Group System↗