Search PubMed⌕ Search

Biomedical subjects

K J Collins

Publications and source records attributed to K J Collins.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effects of age on body temperature and blood pressure in cold environments.

Mean deep body temperature fell by 0.4 +/- 0.1 (SD) degrees C in five sedentary, clothed 63-70 year old men and by 0.1 +/- 0.1 degrees C in four young adults after 2 h exposure in still air at 6 degrees C (P less than 0.001). The mean increase in systolic and diastolic pressure was significantly greater (P less than 0.002) in the older subjects (24 +/- 4 mmHg systolic, 13 +/- 4 mmHg diastolic) than in the young (14 +/- 6 mmHg systolic, 7 +/- 3 mmHg diastolic) after 2 h at 6 degrees C. A small rise in blood pressure occurred in the older men at 12 degrees C, but there was no increase in either group at 15 degrees C. The association of variables is particularly marked between systolic blood pressure and core temperature changes at 6 degrees C. There were no appreciable cold-adaptive changes in blood pressure or thermoregulatory responses after 7-10 days repeated exposure to 6 degrees C for 4 h each day. Blood pressure elevation in the cold was slower but more marked in the older men. These changes in blood pressure may provide a possible basis for delineating low domestic limiting temperature conditions.

Adolescent↗
PubMed1985

Headache.

Explore the source record for details and available documents.

Adolescent↗
PubMed1983

Late onset post-traumatic hypothalamic hypothermia.

A case of post-traumatic hypothalamic hypothermia is described. An unusually selective defect in thermoregulatory function was demonstrated together with a defect in thyroid function suggestive of impaired hypothalamic control.

Body Temperature Regulation↗
PubMed1983

1983 Henderson Award Lecture. Thermal homeostasis in old age.

The relationships of homeostasis to the physiologic and socioeconomic concomitants of aging are presented. Neurohumoral control of body temperature may become deranged in old age as a result of changes in the intrinsic regulatory system. Drugs and stressful climatic temperatures can have deleterious effects. Sensitivity of the elderly to environmental temperature changes is diminished, and their resources to control environmental temperatures are likely to be limited, leaving them more vulnerable than the young to hypothermia and hyperthermia.

Aged↗
PubMed1981

Urban hypothermia: preferred temperature and thermal perception in old age.

A study of 17 elderly men and 13 young adults of similar body build and wearing equivalent clothing insulation (0.8 clo) showed that when given control over their environment the elderly preferred the same mean comfort temperature (22-23 degrees C) but manipulated ambient temperature much less precisely than the young. Slow adjustment of ambient temperature was related to some cases to a higher temperature-discrimination threshold. These findings suggest that both physiological and behavioural changes contribute to the increased vulnerability of old people in cold conditions.

Adolescent↗
PubMed1981

An assessment of anti-schistosomal treatment on physical work capacity.

Acting as their own controls, village subjects from the Gezira are of the Sudan with relatively high levels of schistosomiasis infection were first tested in an exercise laboratory in Khartoum and the tests were then repeated after a period of about 1 yr during which time the subjects were treated with hycanthone and periodically monitored to ensure that they had remained free of the disease. In the meantime they were also given anti-malarial prophylaxis. Laboratory tests showed a significant improvement in physiological work capacity of up to 20% after treatment compared with untreated controls. An overall improvement in pulmonary function, particularly forced vital capacity, was observed as well as a significant increase in mean haemoglobin concentration by 1.1 g/100 ml of blood in the treated group. Apart from these improvements in physical working capacity, the treated subjects subjectively felt better after the exercise tests, as expressed by the disappearance of fatiguability.

Adolescent↗
PubMed1980

Functional changes in autonomic nervous responses with ageing.

The effects of ageing on autonomic nervous responses have been investigated in 29 young adults, 64 healthy elderly in the age range 66 to 86 years, and 20 elderly in-patients with hypothermia, instability of bladder function or marked orthostatic hypotension. In the healthy elderly group, the beat-to-beat variation in response to postural change was significantly diminished, the vasoconstrictor response to cooling reduced and baroreflex sensitivity during lower-body negative pressure was decreased compared with young adults. Patients with an atronic bladder, determined by urodynamic tests, showed an even more marked decrease in baroreflex sensitivity. The multisystem nature of these autonomic disturbances suggests that physiological impairment may occur in autonomic neural pathways with ageing.

Adult↗
PubMed1979

Secretion and metabolism of cortisol and aldosterone during controlled hyperthermia.

1. The rates of secretion and metabolic clearance of cortisol and aldosterone in response to passive heating have been investigated in fifteen young men by the controlled hyperthermia technique combined with continuous I.V. infusion of [14C]cortisol and [3H]aldosterone. 2. During a 1 hr period of elevation of deep body temperature to 38.0 degrees C mean hepatic blood flow measured by indocyanine green clearance decreased by more than 25% compared with normothermic condition. 3. The pattern of response in hyperthermia involved decreasing plasma specific activities indicating increased adrenal secretion of both cortisol and aldosterone. 4. Aldosterone metabolic clearance rate usually decreased in hyperthermia when there was little change in the clearance rate of cortisol, but an increased aldosterone clearance rate was observed when there were significant increases in the clearance rate of cortisol. A contributing factor to elevation of plasma aldosterone concentration in the heat is the reduction in hepatic blood flow which reduces aldosterone metabolic clearance rate. 5. Suppression of the thermally induced rise in plasma cortisol concentration by dexamethasone was associated with a decrease in aldosterone clearance rate which may reflect increased availability of aldosterone-binding plasma protein. 6. Marked rises in plasma cortisol were always accompanied by simultaneous rises in aldosterone, but rises in aldosterone sometimes occurred in the absence of a rise in cortisol. We therefore suggest that ACTH stimulation plays an important, but not exclusive, role in the stimulation of aldosterone secretion during hyperthermia.

Aldosterone↗
PubMed1977

Accidental hypothermia and impaired temperature homoeostasis in the elderly.

A longitudinal study of the age-related decline in thermoregulatory capacity was made in 47 elderly people to try to identify those at risk from spontaneous hypothermia. During the winters of 1971-2 and 1975-6 environmental and body temperature profiles were obtained in the home, and thermoregulatory function was investigated by cooling and warming tests. Environmental temperature and socioeconomic conditions had not changed but the body core-shell temperature gradients were smaller in 1976, indicating progressive thermoregulatory impairment. People at risk of developing hypothermia also seem to have low resting peripheral blood flows, a nonconstrictor pattern of vasomotor response to cold, and a higher incidence of orthostatic hypotension.

Aged↗
PubMed1976

Energy expenditure and physiological performance of Sudanese cane cutters.

The thermal and exercise tolerances of 165 Sudanese cane cutters were measured in the laboratory and related to work performance and productivity in the cane fields. The results showed that the amount of cane cut per minute in the field was significantly correlated with changes in body weight (r = +0-53) during the third hour of work, aerobic energy expenditure (r = + 0-43), and cardiac frequency during work. These variables in turn were associated with predicted maximal power output (VO2 max) measured in the laboratory. The average energy expenditure during cane cutting was 1-66 +/- 0-33 1/min-1 (34-9 kJ/min-1) which represents approximately 60% of the workers predicted VO2 max. This rate of energy expenditure was sustained in the cane fields for at least three hours without significant pauses for rest. The sweat losses measured in 32 cane cutters during the two and three hours of work averaged 637 +/- 221 and 770 +/- 282 g/h-1 respectively, while the mean urine temperature immediately on cessation of effort was 37-74 +/- 0-46 degrees C. Despite the additional environmental heat load of the tropics, it would seem that cane cutters performing a self-paced task demanding heavy physical effort, are able to sustain work levels well in excess of those recommended for most European factory workers without obvious signs of fatigue or heat stress.

Adult↗