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Biomedical subjects

G R CUMMING

Publications and source records attributed to G R CUMMING.

At least 19 recordsLinked to original sources
PubMed1964

RESPONSE OF THE INFANT KIDNEY TO DIURETIC DRUGS.

The diuretic response of normal infants, 6 to 47 days of age, to single doses of mercaptomerin, chlorothiazide, acetazolamide, triamterene and spironolactone was studied by following urinary electrolytes, pH and osmolality. Peak diuresis occured two to four hours after drug administration, and because of compensatory mechanisms little change in urinary excretion was found if only 24-hour urines were studied. Mercaptomerin increased sodium excretion seven-fold, compared to three- to four-fold increases for the other diuretics. Control urinary Na:K ratios averaged 0.68 in infants compared to 2.8 for adults, and mercaptomerin produced the largest increase in this ratio. Qualitatively the response to diuretics is the same in newborn in the ages studied as it is reported to be for adults; no immaturity of the infant kidney in this regard was demonstrated.

Acetazolamide↗
PubMed1963

Indirect measurement of left ventricular function during exercise.

The electrocardiogram, phonocardiogram and carotid pulse curve were recorded during increasing work loads on an electrically braked bicycle. Heart rate increased linearly with increasing work loads while total systole and tension period decreased. In contrast, during the first periods of light work, systolic ejection time increased. As work load increased, the ejection period also decreased. The findings were interpreted as indicating an early increase in stroke volume with exercise and a later increase in the velocity of ejection.

Electrocardiography↗
PubMed1963

Acute hemodynamic effects of angiotensin II. Preliminary report.

Angiotensin II was given to over 200 patients during heart catheterization studies. Left to right shunts through atrial and ventricular septal defects were increased. Shunts not detected under control conditions could then be recognized. In normal subjects left atrial pressure increased about 5-10 mm. Hg, producing a secondary rise in pulmonary artery pressure. The response of the pulmonary vessels to angiotensin was usually passive. Cardiac output declined in the normal subject after angiotensin administration. Right to left shunts decreased after angiotensin administration in some patients with cyanotic congenital heart disease, thus decreasing cyanosis. This finding has possible therapeutic applications. The pulmonary arterioles of patients with pulmonary hypertension may respond to angiotensin in a different manner from those with normal pulmonary arterioles.

Angiotensin II↗
PubMed1963

Working capacity of normal children tested on a bicycle ergometer.

Working capacity defined as that work load performed at a minute pulse rate of 170 was determined in 200 school children aged 6 to 16 and in 40 young adults. Working capacity increased gradually with age and was greater in boys than girls at all ages. The range of normal was large. Working capacities of 11- and 12-year-old Winnipeg children in kg./M./min. were 384 for boys and 300 for girls, these values being 19 and 14% below comparable studies from California and Sweden. Working capacities of Winnipeg student nurses averaged 478 kg./M./min., half the value reported for nurses from Sweden.

Adult↗
PubMed1963

The heart and physical exercise.

Cardiac hypertrophy and extreme bradycardia occur in the highly trained endurance athlete, but not in those with lesser degrees of training. Several longevity studies in athletes fail to show any beneficial effects of athletic training confined to the college years. The invaluable British studies relating physical activity of various occupations to coronary disease show that while exercise does not prevent coronary atherosclerosis, it may reduce the incidence of large and fatal infarctions and of complete coronary obstructions. Various American studies have not confirmed this beneficial effect of exercise. To be of any value in the prevention of coronary disease, exercise must be continued on into middle age. The sedentary life characteristic of western civilization is probably not a major factor in the high incidence of coronary disease.

Cardiomegaly↗