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Biomedical subjects

T Evans

Publications and source records attributed to T Evans.

At least 217 records · Page 12Linked to original sources
PubMed1980

RMI 12330A, an inhibitor of cyclic nucleotide phosphodiesterases and adenylate cyclase in kidney preparations.

N-(cis-2-phenylcyclopentyl)azacyclotridecan-2-imine hydrochloride (RMI 12330A) inhibited cyclic AMP and cyclic GMP phosphodiesterase activities in kidney preparations from rat and mouse. The drug was effective in the concentration range 0.1-1 mM. The agent was much less effective in inhibiting chick kidney cyclic nucleotide phosphodiesterases. The onset of inhibition of rat particulate cyclic AMP phosphodiesterase activities was rapid (less than 30 s) and irreversible. The inhibition of the low Km forms of cyclic AMP phosphodiesterase in mouse kidney homogenates was of the non-competitive type. RMI 12330A inhibited cyclic AMP phosphodiesterase activities in intact rat renal tubules. Adenylate cyclase activity, both basal and stimulated, was inhibited in all three species by the drug. Since RMI 12330A affects cyclic GMP metabolism as well as cyclic AMP metabolism, caution must be exercised in interpreting its effects upon cellular processes in terms of its actions upon the adenylate cyclase-cyclic AMP pathway alone.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1980

Surgical treatment of endomyocardial fibrosis with preservation of mitral valve.

A 48-year-old Kenyan African, who presented with a history of coronary and cerebral embolism, was found to have endomyocardial fibrosis of the left ventricle. It proved possible to remove all diseased tissue at operation, and at the same time to preserve the mitral valve. It is important to inspect the mitral valve from both the atrial and ventricular aspects so that the valve can be spared, if it is not involved in the disease process. The choice of transatrial of transventricular surgical approach for the removal of pathological tissue may depend on whether or not the mitral valve requires replacement.

Endomyocardial Fibrosis↗
PubMed1979

Very slow growth of Escherichia coli.

A recycling fermentor (a chemostat with 100% biomass feedback) was used to study glucose-limited behavior of Escherichia coli B. The expectation from mass transfer analysis that growth would asymptotically approach a limit mass determined by the glucose provision rate (GPR) and the culture's maintenance requirement was not met. Instead, growth proceeded at progressively lower rates through three distinct phases. After the fermentor was seeded, but before glucose became limiting, growth followed the usual, exponential path (phase 1). About 12 h postseeding, residual glucose in the fermentor fell below 1 microgram . ml-1 and the growth rate (dx/dt) became constant and a linear function of GPR (phase 2). The specific growth rate, mu, therefore fell continuously throughout the phase. Biomass yield and glucose assimilation (13%) were near the level for exponential growth, however, and independent of GPR over a broad range. At a critical specific growth rate (0.04 h-1 for this strain), phase 2 ended abruptly and phase 3 commenced. In phase 3, the growth rate was again constant, although lower than in phase 2, so that mu continued to fall, but growth rates and yields were praboloid functions of GPR. They were never zero, however, at any positive value of GPR. By inference, the fraction of metabolic energy used for maintenance functions is constant for a given GPR, although different for phases 2 and 3, and independent of biomass. In both phases 2 and 3, orcinol, diphenylamine, and Lowry reactive materials were secreted at near-constant rates such that over 50% as much biosynthetic mass was secreted as was retained by the cells.

Adenosine Triphosphate↗
PubMed1979

Effect of nifedipine on atrioventricular conduction as compared with verapamil. Intracardiac electrophysiological study.

Intravenous nifedipine, a powerful calcium antagonist, had no obvious effect on atrioventricular conduction when administered to 11 patients during routine intracardiac electrophysiological studies. Verapamil on the other hand showed potent antiarrhythmic properties, depressing atrioventricular nodal conduction. Nifedipine thus appears safe in patients with angina pectoris who have disorders of atrioventricular nodal conduction, and in those receiving beta-adrenergic blocking drugs. There appear to be differential effects on the slow inward channels of cardiac cells with different 'calcium antagonists'.

Adolescent↗
PubMed1979

'Bradycardia-tachycardia' syndrome 8 yr after correction of Fallot's tetralogy.

A 13-yr-old boy presented with atrial flutter 8 yr after surgical correction of tetralogy of Fallot; antiarrhythmic therapy caused depression of the sinoatrial node, with syncope. Disordered sinoatrial function and intraventricular conduction were demonstrated by intracardiac electrography, and appear to have resulted from the operation. Sinoatrial disease may be responsible for supraventricular arrhythmias or syncope long after operative correction of Fallot's tetralogy and may be one of the explanations for the tendency of such patients to die suddenly.

Adolescent↗
PubMed1976

Diabetic emergencies: hypoglycemia and ketoacidosis.

Because hypoglycemia may be rapidly fatal it must be diagnosed and treated early. Ketoacidosis may be difficult to differentiate from hypoglycemia. The diagnosis, treatment and causes of both diabetic emergencies are described. Once rehydration is instituted, further management can be directed using appropriate laboratory and bedside studies that allow stabilization with a high degree of control.

Diabetes Complications↗
PubMed1976

Sustained release procainamide in patients with myocardial infarction.

Sustained release procainamide tablets were administered to 34 patients 48 hours after the onset of an acute myocardial infarct. Therapeutic blood levels of procainamide in the range of 4 to 8 mug/ml were consistently achieved using an 8-hourly maintenance dose of 1.5g after an initial loading dose of 2g. In contrast conventional procainamide capsules administered to 21 comparable patients repeatedly failed to produce plasma concentrations in the therapeutic range, despite the administration of a maintenance dose of 375 mg 3 hourly, after a loading dose of 1g. It is suggested that when the oral administration of procainamide is indicated for the management of ventricular arrhythmias after myocardial infarction, a sustained release preparation should be used.

Delayed-Action Preparations↗