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Biomedical subjects

D Heseltine

Publications and source records attributed to D Heseltine.

18 recordsLinked to original sources
PubMed1991

Erythrocyte sodium, potassium and sodium fluxes with cell and subject ageing.

In young subjects erythrocyte sodium was lower in females than in males. In males juvenile erythrocyte sodium decreased with subject age whereas in females aged erythrocyte sodium increased with subject age. Therefore, the difference in erythrocyte sodium between young male and female subjects was not observed in the elderly. These differences in erythrocyte sodium appeared to be mainly due to differences in the sodium pump rate constant. In juvenile cells from young subjects the sodium pump rate constant was related to the ouabain sensitive sodium flux rate, but not in elderly subjects, suggesting disturbed control of cell sodium in the latter group. Juvenile erythrocytes had a higher potassium content in elderly than young subjects but this was mainly in the 'frail' hospitalised elderly and it decreased more rapidly with cell ageing. This could indicate more active erythrocytes entering the blood in elderly subjects and then ageing more rapidly. Differences between young and elderly subjects in erythrocyte sodium, potassium and sodium pump rate constant were more marked in the 'frail' hospitalised elderly.

Adult↗
PubMed1991

Effects of carbohydrate type on postprandial blood pressure, neuroendocrine and gastrointestinal hormone changes in the elderly.

Previous studies have demonstrated that blood pressure falls postprandially in fit elderly subjects, the greatest changes occurring after meals with a high carbohydrate content. To evaluate the influence of the type of carbohydrate on postprandial blood pressure, the effects of equivalent energy content (2.4 MJ) high complex (starch) and high simple (monosaccharide) carbohydrate meals were studied in seven healthy elderly subjects. Blood pressure, heart rate, autonomic function, plasma catecholamines, insulin and neurotensin levels were measured pre- and postprandially. Greater falls in supine and erect systolic blood pressure occurred after the high simple than the high complex carbohydrate meal (p less than 0.05). No differences were found in supine or erect diastolic blood pressure, heart rate or in any of the biochemical parameters measured between the meal types. It is concluded that a simple carbohydrate meal results in a greater postprandial fall in blood pressure than an equivalent energy complex carbohydrate meal in the elderly, although the mechanisms for these changes are unknown.

Aged↗
PubMed1991

The effect of caffeine on postprandial hypotension in the elderly.

In a double-blind, randomized trial the effects of caffeinated and decaffeinated drinks on postprandial hemodynamic and neurohumoral changes were studied in seven fit, elderly subjects after a standard 2.4MJ meal. There was a significant difference in supine postprandial systolic blood pressure between the placebo and caffeine phases (P less than 0.01); at 60 minutes, supine systolic blood pressure had fallen 14 mmHg [95% confidence interval (CI)-7 to-21 mmHg, p less than 0.01) after placebo, but was unchanged after caffeine (+9 mmHg, CI 0 to 18 mmHg, NS]. Similar differences between placebo and caffeine were seen in erect systolic and diastolic blood pressure (P less than 0.01), although orthostatic tolerance was maintained throughout each study period. Postprandial plasma noradrenaline levels were higher (P less than 0.02) and the increase greater (P less than 0.02) after caffeine than after placebo. Caffeine administered at the end of a standard test meal prevents the postprandial fall in blood pressure in fit, elderly subjects. The clinical relevance of this finding has yet to be determined, but it may offer a simple remedy for patients with symptomatic postprandial hypotension.

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PubMed1991

The effect of caffeine on postprandial blood pressure in the frail elderly.

In a double-blind, random-order, cross-over study the effects of placebo and 100 mg of caffeine on postprandial sitting and erect blood pressure and heart rate were studied in 20 frail elderly subjects (mean age 84, range 75-93 years) after a standardized 400 K-calorie glucose drink. Maximal postprandial reduction in sitting systolic blood pressure occurred, at 60 minutes post-placebo, of - 11 mmHg (95% confidence interval -5 to -17 mmHg, P less than 0.01), and was attenuated by caffeine (P less than 0.05) with changes in systolic blood pressure, at 60 minutes post-drink, of 1 mmHg (95% CI -6 to 7 mmHg, not significant). Four subjects developed symptomatic postprandial hypotension after placebo which was prevented by caffeine. There were no significant changes in erect systolic blood pressure, postural systolic blood pressure change, sitting and erect, diastolic blood pressure and heart rate between treatment phases. Caffeine attenuates the postprandial fall in sitting blood pressure in frail elderly subjects and in particular prevented symptomatic blood pressure reductions in subjects with postprandial hypotension.

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PubMed1990

Blood pressure, heart rate and neuroendocrine responses to a high carbohydrate and a high fat meal in healthy young subjects.

1. The responses of blood pressure, heart rate, autonomic function and plasma insulin to a high carbohydrate and a high fat meal of equivalent energy value were studied in nine young volunteers. 2. Neither meal produced a significant change in supine or erect blood pressure. The high carbohydrate meal, however, resulted in an overall rise in both supine (6 beats/min) and erect (6 beats/min; P less than 0.05) heart rate, no such changes being seen after the high fat meal. 3. Plasma noradrenaline levels increased by a maximum of 126% at 90 min (0.98 to 2.22 nmol/l) after the high carbohydrate meal but were virtually unchanged after the high fat meal (P less than 0.01). Parasympathetic function showed no between-meal differences. Plasma insulin and glucose levels were significantly higher after the high carbohydrate meal than after the high fat meal. No postprandial difference in packed cell volume was found between meal types. 4. We conclude that, in young subjects, the postprandial blood pressure after a high carbohydrate meal is maintained by an increase in heart rate associated with increased sympathetic nervous system activity. These changes are at variance with the blood pressure and heart rate responses seen in the elderly after a high carbohydrate meal. A high fat meal has no significant cardiovascular or neuroendocrine effects in the young or old. The nutrient composition of meals has to be taken into account when studying the postprandial cardiovascular and neuroendocrine responses in the young.

Adult↗
PubMed1990

Potassium supplementation in the treatment of idiopathic postural hypotension.

We studied the effects of potassium supplementation (60 mmol/day) and matching placebo on the postural blood-pressure fall in ten elderly patients with symptomatic idiopathic postural hypotension in a double-blind, randomized cross-over trial. There was a significant decrease in the orthostatic fall in systolic blood pressure (SBP 33 +/- 5 mmHg to 16 +/- 9 mmHg, p less than 0.01) and in supine SBP (162 +/- 7 to 150 +/- 7 mmHg, p less than 0.01) between placebo and potassium phases. Supine diastolic and erect blood pressures were unchanged, though pulse rate showed a greater orthostatic increase (7 +/- 3 beats/min to 14 +/- 2 beats/min, p less than 0.05) following potassium therapy. No significant changes were seen in intracellular electrolytes, plasma renin activity, aldosterone levels or body weight. Seven patients reported symptomatic improvement with potassium, but none during the placebo phase. Potassium therapy was well tolerated and may be a successful and safe method of treating idiopathic postural hypotension.

Aged↗
PubMed1989

Effects of meal composition on the postprandial blood pressure, catecholamine and insulin changes in elderly subjects.

1. The effects of four meals of similar energy, but different nutritional, composition on postprandial blood pressure, heart rate, autonomic function, catecholamines, insulin and packed cell volume levels were studied in seven fit elderly subjects. 2. The high carbohydrate and high protein meals led to a significant overall fall in supine systolic and diastolic blood pressure compared either with no change or a rise after the normal (i.e. mixed) and high fat meals. Similar between-meal differences were seen with erect diastolic but not erect systolic blood pressure. No significant postural blood pressure fall occurred after any of the meals. Supine heart rate was unaffected by meal type or by time, and although erect heart rate showed a small increase during the study there was no between-meal difference. 3. Parasympathetic function was unaffected by meal type. Plasma noradrenaline rose after the high carbohydrate and mixed meals only, remaining elevated for 120 min after meal consumption. This increase was not related to the changes in blood pressure or plasma insulin levels. 4. Plasma insulin and glucose rose after the high carbohydrate and mixed meals, but were unchanged after the high protein and high fat meals. Packed cell volume showed a small decrease towards the end of the study, although there was no between-meal variation. 5. The differences in the cardiovascular changes after the different meals could not be ascribed to alterations in autonomic function, insulin release or fall in plasma volume. We propose that the postprandial changes in blood pressure are due to the nutrient composition of the meal rather than the actual energy load.

Aged↗
PubMed1989

Testicular enlargement and elevated serum inhibin concentrations occur in patients with pituitary macroadenomas secreting follicle stimulating hormone.

We studied four male patients with pituitary macroadenomas. Before treatment all had high serum FSH concentrations, but LH and testosterone were normal or subnormal; all patients were found to have large testes. All had had normal sexual function, and three patients had fathered children. After pituitary surgery there were decreases in serum gonadotrophins and testosterone, which were accompanied by decreases in testicular volumes. hCG stimulation tests in two patients showed normal responses of testosterone and oestradiol, confirming normal Leydig cell function. Inhibin levels were increased in two patients studied when FSH levels were high, suggesting a defect in gonadal-pituitary feedback control. Later, as FSH concentrations decreased to normal, so did inhibin levels. Histology showed that increased testicular size was due to increased lengths of seminiferous tubules. The association of pituitary macroadenomas, large testes and increased serum inhibin has not been reported previously. Assessment of testicular size in patients with raised serum FSH is important, since enlarged testes suggest the likely pathogenesis is that of a pituitary gonadotrophinoma, rather than primary gonadal failure. Increased inhibin levels may then confirm this, and be a biochemical marker for these tumours.

Adenoma↗
PubMed1988

Unilateral facial pain in patients with lung cancer: a referred pain via the vagus?

In 8 patients presenting with unilateral facial pain, subsequent investigation revealed an ipsilateral lung tumour. The interval between presentation with the pain and the discovery of the lung cancer varied between 6 wk and 4 yr. Radiotherapy cured the facial pain in 7 cases. Facial pain may be caused by lung cancer, and could be referred to the face via the vagus nerve.

Adult↗
PubMed1988

High erythrocyte water content causes discrepancy between values of automated and micro-centrifuged haematocrit.

Erythrocyte water content, micro-haematocrit (micro-Hct) and haematocrit (Hct) as derived by Coulter Counter were determined on 41 subjects. Significant discrepancies were observed between manual and automated Hct which could not be explained by abnormal red cell morphology and abnormal plasma osmolality, but appeared to be related to high erythrocyte water content (r = 0.54, p less than 0.001). As human ageing is associated with increased erythrocyte water content, these results question the reliability of Hct readings in the elderly. Further studies need to be performed to evaluate which estimation of Hct should be applied for subjects with high erythrocyte cell water.

Adult↗
PubMed1988

Loop diuretics cause less postural hypotension than thiazide diuretics in the frail elderly.

Seventy frail elderly patients attending a day hospital were studied to investigate the incidence of postural hypotension in control patients on no diuretic treatment (n = 30), patients on loop diuretics (frusemide) for mild cardiac failure (n = 20) and patients on thiazide diuretics for mild cardiac failure (n = 20). The results showed that patients on thiazide diuretics had a higher incidence of postural hypotension (reduction in systolic blood pressure greater than 20 mmHg on standing after 2 minutes) than patients on loop diuretics (12 out of 20 vs 4 out of 20, p less than 0.05). Mean plasma potassium levels were lower in the thiazide group than in the frusemide group (p less than 0.05) and this correlated significantly with change in systolic blood pressure from supine to standing position (r = -0.56, p less than 0.01). These findings indicate that a loop diuretic (frusemide) is as safe if not safer than thiazides in older patients and the latter have an unjustified reputation of being safer first-line drugs for the treatment of cardiac failure.

Aged↗