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Biomedical subjects

I B Puddey

Publications and source records attributed to I B Puddey.

104 records · Page 6Linked to original sources
PubMed1985

Sulphate conjugation limits fluctuations in free catecholamines in phaeochromocytoma.

More than 80% of total noradrenaline (NA) and adrenaline (A) and nearly 100% of dopamine (DA) circulate in blood as sulphates, and it has been proposed that sulphate conjugation contributes to the inactivation of catecholamines (CA). Sulphate conjugation rapidly responds to changes in sympathetic activity and may buffer the haemodynamic and metabolic consequences of wide fluctuations in CA release in phaeochromocytoma. This hypothesis was tested in seven patients with phaeochromocytoma by consecutive measurements of plasma-free and conjugated NA, under resting conditions, before operation and at least 4 weeks after tumour removal. Free and total (free + sulphates) NA were markedly elevated before compared with 1-4 months after surgery. Similar elevations were seen in free and total A and free DA. Before surgery consecutive measurements of total NA, 5 min apart, were markedly different (17 +/- 4.1 and 13.7 +/- 4.4 ng/ml, respectively), whereas only small differences in free NA levels were present (4.1 +/- 1.5 and 4.3 +/- 1.8 ng/ml). These differences between total and free levels were also apparent for A and DA, but to a lesser degree. In three patients, fluctuations in total NA concentration greater than 12 ng/ml were associated with either no change (one patient) or changes of 0.6 and 2.8 ng/ml in free levels for the other two patients, respectively. Mean blood pressure (BP) varied less than 8 mmHg in these patients. These findings suggest that sulphate conjugation is a dynamic process which may limit wide fluctuations in free CA concentration during episodic secretory activity in phaeochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1985

Alcohol stimulation of renin release in man: its relation to the hemodynamic, electrolyte, and sympatho-adrenal responses to drinking.

Alcohol stimulation of the renin-angiotensin axis has been proposed as an explanation for the higher blood pressure in drinkers. This study examines the acute effects of moderate alcohol intake on PRA in relation to change in fluid and electrolyte balance, sympatho-adrenal activity, blood pressure, and heart rate in 20 normal men, aged 20-24 yr. They consumed either 750 ml nonalcoholic beer as a control or the same beverage with 1 ml/kg alcohol added, which increased the plasma alcohol concentration to 16.7 +/- 1.0 (+/- SE) mM within 70 min. PRA increased more than 2-fold 90 min after the ingestion of alcohol. This was accompanied by a decrease in diastolic blood pressure and a fall in plasma potassium, both possible stimuli to the rise in PRA. A late increase in plasma sodium, also occurring 90 min after alcohol ingestion, was attributed to plasma volume contraction after an alcohol-induced diuresis. This may have been an additional factor in stimulating renin release. Norepinephrine levels increased during both alcohol and control studies. In contrast, plasma epinephrine decreased significantly during the control study, but did not change after alcohol ingestion. Hence, alcohol stimulation of sympathetic nervous activity is unlikely to have mediated the renin release. We conclude that the acute increase in PRA associated with moderate alcohol consumption is predominantly a secondary response to changes in fluid and electrolyte balance and blood pressure. Although a direct action of alcohol on renin release was not excluded, the possibility that repeated activation of the renin-angiotensin system mediates the pressor effect of regular moderate alcohol consumption is, therefore, diminished.

Adult↗
PubMed1984

Smoking withdrawal programme: baseline indicators of smoking exposure and biochemical monitoring of successful outcome.

Sixty-four subjects who participated in a smoking withdrawal programme were analysed with respect to the relative usefulness of biochemical and hematological indices of smoking exposure. Plasma thiocyanate was found to be the best biochemical correlate of baseline cigarette consumption when compared to salivary thiocyanate or expired air carbon monoxide. Both plasma and salivary thiocyanate also correlated significantly with depth of inhalation per cigarette but not with any other questionnaire index of smoking exposure. After six weeks of successful smoking cessation all three indices fell significantly. Plasma thiocyanate proved the most sensitive biochemical index for monitoring ultimate outcome, accurately dichotomizing 90% of subjects as successful or unsuccessful in their attempts to stop smoking. The use of all three variables allowed accurate classification of 96% of subjects. White cell count, red cell count and hemoglobin also correlated significantly with baseline cigarette consumption and a significant decrease in these hematological indices occurred consequent to successful smoking cessation. However, these hematological changes were not as sensitive as biochemical indices in monitoring successful outcome.

Adult↗
PubMedDate not supplied

Comparison of oscillometric blood pressure measurements at the wrist with an upper-arm auscultatory mercury sphygmomanometer.

1. Oscillometric devices for blood pressure (BP) measurement at the wrist are becoming more widely used in clinical practice. However, systematic comparisons with standard auscultatory BP measurement at the brachial artery are scarce. Therefore, we compared two such devices, the Boso-Mediwatch (Bosch & Sohn GmbH U. Co., Jungingen, Germany) and the Omron R3 (Omron Corp., Tokyo, Japan), with upper-arm auscultatory mercury sphygmomanometry. 2. In 20 normotensive subjects and 20 treated hypertensive subjects, the Boso-Mediwatch was applied to the left wrist by observer 1 and was compared with mercury sphygmomanometry of the right upper arm by observer 2. Each observer swapped sides and the procedure was repeated. The Boso-Mediwatch was then applied to the right wrist by observer 1 and was compared with mercury sphygmomanometry of the left upper arm by observer 2. Each observer once again swapped sides and the procedure was repeated. An identical protocol was followed for the Omron R3 in a further 20 treated hypertensive subjects and 20 normotensive subjects. 3. There were no significant differences between observers or left versus right arm for either oscillometric device or when measurements were performed by mercury sphygmomanometry. In normotensive subjects, the Boso-Mediwatch readings were higher than mercury sphygmomanometer readings, with mean differences (95% confidence intervals) of 3.9 (0.1, 7.6; P = 0.045) and 7.0 mmHg (4.7, 9.2; P < 0.001) for systolic and diastolic BP, respectively. In hypertensive subjects, the Boso-Mediwatch readings were lower for systolic BP (mean difference -6.0 mmHg (-11.6, -0.3; P = 0.04) but were higher for diastolic BP (mean difference 3.8 mmHg (1.4, 6.3; P < 0.01). 4. In normotensive subjects, the Omron R3 readings were higher, with mean differences of 3.2 (0.6, 5.8; P = 0.018) and 4.2 mmHg (1.6, 6.7; P = 0.003) for systolic and diastolic BP, respectively. In hypertensive subjects, the Omron R3 readings were lower for both systolic and diastolic BP (mean differences: -5.8 (-8.8, -2.8; P = 0.001) and -5.5 (-9.3, -1.6; P = 0.008), respectively). 5. For the Boso-Mediwatch, weighted least products analysis confirmed the presence of both fixed and proportional error for systolic BP but not for diastolic BP. For the Omron R3, fixed or proportional error was not detected for either systolic or diastolic BP. 6. These wrist oscillometric devices, although offering portability and convenience, give BP measurements that frequently differ substantially (by at least 5 mmHg) from readings simultaneously measured at the upper arm by a mercury sphygmomanometer. The magnitude and direction of differences detected are dependent on both the device used and the underlying level of BP.

Adult↗
PubMedDate not supplied

Haemodynamic and neuroendocrine consequences of stopping smoking--a controlled study.

The haemodynamic and neuroendocrine consequences of stopping smoking for a 6 week period were studied in thirty-three smokers and their matched controls. Complete smoking cessation was associated with a significant fall in adrenaline and cortisol levels, consistent with the withdrawal of a nicotine stimulus to adrenomedullary and cortical activity. Supine systolic and diastolic blood pressure did not change significantly. However, the response to a cold pressor stimulus was altered with a delay in return of systolic blood pressure to basal values. This study has been unable to confirm findings from epidemiological studies of lower blood pressure in smokers. However, the possibility is raised that this phenomenon may be due to modification by smoking of the normal physiological response to stressful stimuli.

Blood Pressure↗
PubMedDate not supplied

A randomized controlled trial of the effect of alcohol consumption on blood pressure.

Forty-six healthy normotensive male drinkers participated in a randomized, controlled, crossover trial to study the effects of varying alcohol intake on blood pressure. Alcohol consumption (calculated from weekly diaries) was reduced from 336.3 (s.e.m. = 20.2) to 64.5 (s.e.m. = 5.6) ml ethanol/week by drinking low alcohol content beer alone. Systolic blood pressure fell significantly during reduction of alcohol intake and rose again when normal drinking habits were resumed, the mean difference during the last 2 weeks of normal or low alcohol intake being 3.8 mmHg. This effect of alcohol on blood pressure was independent of a small but significant decrease in weight following reduction of alcohol intake. The change in blood pressure correlated with change in alcohol consumption (r = 0.53, P less than 0.001) with a 1 mmHg fall predicted for each 100 ml of reduction in ethanol intake/week. We conclude that regular moderate alcohol consumption has a direct (but reversible) pressor effect in normotensive men.

Adult↗
PubMedDate not supplied

Hypertension management: a comparison of urban versus rural general practitioners in Western Australia.

1. We have conducted a survey of 75 rural and 75 urban randomly selected general practioners (GPs) in Western Australia to ascertain how closely current practice mirrors published Australian guidelines for the management of hypertension. 2. Fifty-one rural and 49 urban GPs completed the 19 item questionnaire. The two groups were well matched in terms of age and years in general practice. An assessment of the criteria utilized to diagnose hypertension revealed a tendency for much greater scatter in the cut points used to define systolic compared to diastolic hypertension, but no systematic difference between urban and rural GPs. 3. After an initial finding of mild hypertension the follow-up time to the next check-up was significantly longer for rural patients compared to urban patients (72 +/- 13 and 36 +/- 5 days respectively, P < 0.01). Urban GPs reviewed established hypertensive patients more commonly at 1-3 monthly intervals (89%) while rural GPs reviewed more commonly at 3-6 monthly intervals (86%). 4. In terms of target blood pressure (BP) for BP reduction, 67% rural compared to 83% urban GPs aimed for a systolic BP of < 140 mmHg (P = 0.06), while 95% of both groups aimed for diastolic BP < 90 mmHg. 5. The profile of first line antihypertensive agents most commonly used was also similar in both groups with 46% preferring angiotensin converting enzyme inhibitors, 18.5% diuretics, 18.5% beta blockers, 16% calcium entry blockers and 1% prazosin. 6. This study demonstrates a clear preference for the newer anti-hypertensive agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive Agents↗
PubMedDate not supplied

Determinants of change in blood pressure during S.W.E.A.T.: the sedentary women exercise adherence trial.

1. In a long-term study of the optimal approach to initiating and maintaining a regular exercise programme in previously sedentary older women (40-65 years), we have assessed determinants of change in resting blood pressure (BP) after 6 and 12 months. 2. Women (n = 126) were randomly assigned to either a centre-based or home-based exercise programme for an initial 6 months. The centre-based group attended supervised sessions three times per week, while the home-based group exercised unsupervised at home three times per week. Both groups were home-based during a second 6 months. Within each arm, subjects were further randomized to either exercise at moderate intensity (40-55% heart rate reserve; HRres) or at vigorous intensity (65-80% HRres). A nonintervention comparison group of 30 women was followed throughout. 3. At 6 months there was a fall in BP with moderate, but not vigorous intensity exercise (-2.7 mmHg; P = 0.025), an effect no longer significant at 12 months. 4. Change in BP was unrelated to improvements in fitness (VO2max), increases in lean tissue mass, number of exercise sessions completed or a composite measure of the total number of exercise sessions completed multiplied by the mean exercise intensity expressed as a percentage of heart rate reserve (%HRres). 5. Continuing participation in any regular exercise was a consistent predictor of change in BP, with those subjects still exercising in the 2 weeks before BP measurement having 1.9 mmHg lower BP at 6 months (P = 0.038) and 3.8 mmHg lower BP at 12 months (P = 0.016). 6. We conclude that the small effects of exercise on resting BP in these older women are predominantly related to continuing participation in lower intensity exercise, rather than to improvements in fitness or body composition.

Adult↗
PubMedDate not supplied

Evidence for a direct effect of alcohol consumption on blood pressure in normotensive men. A randomized controlled trial.

A direct pressor effect of alcohol is proposed as the basis for the association between regular alcohol consumption and an increase in blood pressure found in population studies. To examine this further, a randomized controlled crossover trial of the effects of varying alcohol intake on blood pressure in 46 healthy male drinkers was conducted. From an average of 336 ml of ethanol per week, alcohol consumption was reduced by 80% for 6 weeks by drinking a low alcohol content beer alone. This reduction was associated with a significant reduction in systolic and diastolic blood pressure (p less than 0.001 and p less than 0.05 respectively). The mean difference in supine systolic blood pressure during the last 2 weeks of normal or low alcohol intake was 3.8 mm Hg, which correlated significantly with change in alcohol consumption (r = 0.53, p less than 0.001). Reduction of alcohol intake also caused a significant decrease in weight (p less than 0.001). After adjustment for weight change, an independent effect of alcohol on systolic but not diastolic blood pressure was still evident, with a 3.1 mm Hg fall predicted for a decrease in consumption from 350 ml of ethanol equivalent per week to 70 ml per week (p less than 0.01). Systolic blood pressure rose again when normal drinking habits were resumed. These results provide clear evidence for a direct and reversible pressor effect of regular moderate alcohol consumption in normotensive men and suggest that alcohol may play a major role in the genesis of early stages of blood pressure elevation.

Adult↗
PubMedDate not supplied

Sulphate conjugation limits fluctuations in free catecholamines in phaeochromocytoma.

Sulphate conjugation represents an efficient mechanism for inactivating catecholamines (CA) with more than 80% of total noradrenaline (NA) and adrenaline (A) and nearly 100% of dopamine (DA), circulating as conjugates. Sulphate conjugation responds rapidly to changes in sympathetic activity and may buffer the haemodynamic and metabolic consequences of wide fluctuations in CA release in phaeochromocytoma. This hypothesis was tested in seven patients with phaeochromocytoma by consecutive measurements of plasma free and conjugated NA, under resting conditions, before operation and at least 4 weeks after tumour removal. Free and total (free plus sulphates) NA were markedly elevated before (4.3, s.e.m. = 1.8 and 13.7, s.e.m. = 4.4 ng/ml, respectively) compared with 1-4 months after surgery (0.48, s.e.m. = 0.13 and 1.8, s.e.m. = 0.53 ng/ml). A and DA were similarly elevated before surgery; after surgery, A was undetectable in three patients and DA was undetectable in all patients. Before surgery consecutive measurements of total NA, 5 min apart, were markedly different (18.8, s.e.m. = 4.8 and 12, s.e.m. = 3.1 ng/ml, respectively), whereas only small differences in free NA levels were present (4.0, s.e.m. = 1.5 and 4.4, s.e.m. = 1.8 ng/ml). In three patients, fluctuations in total NA concentration greater than 12 ng/ml were associated with either no change (one patient) or changes of 0.6 and 2.8 ng/ml in levels of free NA, respectively. Mean blood pressure varied less than 8 mmHg in these patients. These findings indicate that sulphate conjugation is a dynamic process which may limit wide fluctuations in free CA concentration during episodic secretory activity in phaeochromocytoma.

Adrenal Gland Neoplasms↗