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Biomedical subjects

D M Park

Publications and source records attributed to D M Park.

At least 37 records · Page 2Linked to original sources
PubMed1976

Differences in the metabolic and hormonal response to exercise between racing cyclists and untrained individuals.

1. Six well-trained cyclists and six untrained subjects were studied during and immediately after four successive 7 min periods of exercise at 30, 45, 60 and 75% of their maximal work capacity. 2. Venous blood samples were taken at rest, at the end of each exercise period and 5 min following the end of exercise, for estimation of metabolites in blood and plasma insulin, growth hormone, cortisol and catecholamines. 3. The results showed significant differences in the mobilization and utilization of muscle fuels between the athletically fit cyclists and the untrained group. In the cyclists, glucose, glycerol and free fatty acid concentrations were higher, but lactate, pyruvate and alanine were lower than in the untrained subjects during exercise. 4. Plasma catecholamines rose in both groups during exercise but the rise was significantly less in the racing cyclists. Plasma insulin was depressed to a greater extent in the untrained subjects during exercise and plasma glucagon rose to a greater extent during strenuous exercise and remained elevated after the end of exercise in the untrained group. Plasma human growth hormone rose to a greater extent during exercise and remained elevated after the end of exercise in the untrained group. Plasma cortisol fell at low and moderate exercise rates in both groups, but to a smaller extent in the cyclists. Cortisol values rose at higher workloads and were significantly higher in the cyclists at the end of exercise. 5. It is concluded that there are significant differences in the metabolic and hormonal responses to exercise between athletically trained and untrained individuals, even when the physically fit subjects work at the same percentage of their maximal capacity as the unfit subjects.

Adult↗
PubMed1976

Nomifensine in parkinsonism.

Nomifensine, a tetrahydroisoquinolone antidepressant which facilitates dopaminergic and noradrenergic transmission, was studied in 28 Parkinsonism patients most of whom were also receiving conventional medications. Double-blind evaluations revealed a moderate therapeutic action at a mean dose level of 150 mg daily. Adverse reactions were encountered, similar to those identical by levodopa.

Aged↗
PubMed1976

Uptake and release of hormones and metabolites by tissues of exercising leg in man.

To examine release of insulin from tissues of the exercising llin, growth hormone, cortisol, and circulating metabolites were studied in five men before, during, and after exercise on a bicycle ergometer at 60% of their maximum work capacity. At rest, insulin, growth hormone, and cortisol were taken up by leg tissues. During exercise arterial plasma insulin concentration fell, but cortisol and growth hormone levels rose; there was net release of insulin into venous blood but little change in uptake of cortisol and growth hormone. Insulin release persisted after exercise for 15-30 min. During exercise arterial concentrations and uptake of glucose and free fatty acids (FFA) increased. Examination of the changes in hormones and metabolites failed to identify any single hormonal or metabolic factor causing the observed reversal of insulin uptake with exercise.

Adult↗
PubMed1975

Raised intracranial pressure and cerebral blood flow. 5. Effects of episodic intracranial pressure waves in primates.

The effects of episodic waves of intracranial pressure on cerebral blood flow were studied in primates. Six pressure waves each of 20 minutes' duration and ranging from 50 to 100 mmHg in magnitude were induced in baboons, at intervals of 30 minutes, in an attempt to simulate clinical plateau waves. With pressure waves up to 75 mmHg, cerebral blood flow remained at control levels despite falling cerebral perfusion pressures. Between the initial pressure waves a marked hyperaemia developed, with cerebral blood flow increasing by as much as 100%, and this appeared to be a means whereby adequate flow was maintained during pressure waves. Later pressure waves, up to 100 mmHg, eventually reduced blood flow below control levels, although moderately high flows were maintained during periods of very low perfusion pressure. Brain metabolism was affected by eht episodic pressure waves, although no consistent change was seen.

Acetoacetates↗
PubMed1973

Recurrent hyperkalaemia due to selective aldosterone deficiency: correction by angiotensin infusion.

A patient with recurrent weakness and blurring of consciousness associated with hyperkalaemia due to aldosterone deficiency is reported. The plasma concentrations of renin, angiotensin II, and aldosterone were low and did not increase during sodium deprivation. Blood angiotensin I was also low while renin-substrate concentration was normal. Infusion of angiotensin produced a distinct rise in plasma aldosterone. The patient was treated successfully with fludrocortisol.The results support the concept that the renin-angiotensin system is an important regulator of aldosterone secretion and that in the syndrome of acquired selective hypoaldosteronism the primary abnormality may be a deficiency of renin. It is suggested that a selective lack of aldosterone should be considered in all cases of otherwise unexplained hyperkalaemia.

Adrenal Glands↗
PubMed1973

Intermittent hypothermia. Independence of central and reflex thermoregulatory mechanisms.

Three patients who had suffered episodes of spontaneous hypothermia are described. Circulatory control was normal for their age but there was evidence of a persistent defect of thermoregulatory mechanisms. In all patients vascular thermoregulatory reflexes dependent upon peripheral receptors were active and in two patients reflex shivering could be obtained. There appeared, however, to be a failure of central thermoregulation as the vascular reflexes were active at abnormally low central temperatures and a fall in central temperature did not initiate shivering. It is concluded that in patients who have suffered spontaneous hypothermia there may be a persistent defect of central mechanisms subserving vasomotion and shivering, although thermoregulatory reflexes dependent upon peripheral receptors can be active. The reflex pathways for thermoregulation in man therefore have a separate integrity, physiologically independent of the central thermoregulatory mechanisms.

Aged↗