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Biomedical subjects

I B Puddey

Publications and source records attributed to I B Puddey.

At least 73 records · Page 4Linked to original sources
PubMed1996

Alcohol and hypertension--kill or cure?

An association between alcohol consumption and blood pressure levels has been observed in over 60 population studies world wide. The relationship is generally linear but with some studies showing a threshold effect at around 2-3 standard drinks a day. Effects are seen with all types of alcoholic beverages, and in men and women. The affect appears additive to effects of obesity and higher dose oral contraceptives. Studies of acute effects of alcohol suggest an initial vasodilator response, while population studies suggest that heavy drinkers may show some rebound hypertension. Randomized controlled trials show that reducing alcohol consumption lowers blood pressure in both treated and untreated hypertensives. Mechanisms of alcohol induced hypertension are still unclear. Despite predisposing to hypertension, regular light to moderate drinking (1-4 standard drinks a day) appears to protect against coronary deaths and ischaemic strokes, while heavier drinking increases the risk of haemorrhagic stroke and heart disease. There is some suggestion that wine drinking may be associated with lower cardiovascular risks, however in a study of 343 working men we found that beverage preference and drinking patterns correlated strongly with diet habits, smoking education and socioeconomic status, factors that are likely to confound the interpretation of epidemiological studies suggesting favourable cardiovascular effects to a particular beverage. Although light drinkers have lower mortality than non drinkers those drinking more than 2 standard alcohol drinks per day show a rising mortality as well as an increased risk of hypertension. Those facts should be the basis of public health advice on 'safe' levels of drinking.

Alcohol Drinking↗
PubMed1995

Absence of increased susceptibility of LDL to oxidation in type 1 diabetics.

Insulin-dependent diabetics have a greatly increased risk of developing premature coronary artery disease which is not entirely explained by known risk factors. A possible explanation may be enhanced oxidative modification of low density lipoprotein (LDL). The aim of this study was to determine firstly, whether or not LDL from moderately well controlled type 1 diabetics is more readily oxidisable than LDL from healthy non-diabetics and, secondly, to assess whether potential predictors of LDL oxidisability differ between type 1 diabetics and controls. Twenty type 1 diabetic men were carefully matched with healthy non-diabetic men on the basis of age and body mass index and each pair attended the department on the same morning for blood sampling. LDL oxidisability was assessed using both copper in PBS, 15 and 30 mM glucose, and with AAPH. There was no difference between type 1 diabetics and controls in the susceptibility of the LDL to either copper-dependent or non-transition metal-dependent oxidation. Furthermore, there was no difference between the groups for LDL vitamin E content, LDL fatty acid composition in cholesteryl esters, triglycerides or phospholipids, or LDL copper reductive capacity, but LDL glycation was elevated in the IDDM subjects. Given the absence of increased LDL oxidisability in these subjects, the recommendation of vitamin E supplementation in type 1 diabetics should be considered a secondary priority to achieving adequate glucose control.

Adult↗
PubMed1995

Exercise in the prevention and treatment of hypertension.

There is substantial evidence to suggest that regular physical activity reduces the risk of heart disease. Less clear is the extent to which this is caused by blood pressure reduction. This review considers effects of exercise on blood pressure and overall cardiovascular risk in normotensive and hypertensive individuals.

Exercise Therapy↗
PubMed1995

Increased blood pressure and changes in membrane lipids associated with chronic ethanol treatment of rats.

1. Changes in membrane fluidity have been proposed to contribute to the pathogenesis of ethanol-induced hypertension possibly through changes in membrane lipid patterns, but reports are inconsistent. 2. In a controlled trial we documented ethanol-induced changes in blood pressure and composition of membrane lipids in ethanol-fed rats. 3. Systolic blood pressure increased significantly in the ethanol-treated rats (9.3 mmHg, s.e.m. 2.9) compared with the control group (-1.3 mmHg, s.e.m. 2.6). Mean cholesterol content in red cell membranes did not differ significantly between ethanol-fed and control rats. Phospholipids of aorta, red cells and kidney showed a significant decrease in the polyunsaturated to saturated fatty acid ratio, while membrane phospholipids from the heart showed a significant increase in the polyunsaturated to saturated fatty acid ratio with ethanol treatment. 4. In univariate regression blood pressure was significantly negatively related to levels of arachidonic acid in the kidney (P = 0.0013) and to linoleic acid in the aorta (P = 0.0341) and red cells (P = 0.0289). Blood pressure was not significantly related to fatty acids in the heart nor to membrane cholesterol or phospholipids. 5. Differences in fatty acid composition of phospholipids between controls and ethanol-fed rats are consistent with altered membrane fluidity. Altered membrane function is a potential mechanism involved in ethanol-induced hypertension.

Animals↗
PubMed1993

Genetic and environmental covariance of serum cholesterol and blood pressure in female twins.

Blood pressure elevation is frequently associated with elevated cholesterol, triglyceride or low density lipoprotein (LDL-C) or low high density lipoprotein (HDL-C). The relative importance of genetic and environmental factors in these associations is unclear. We examined the relative contribution of genetic and environmental influences to the association between blood pressure and serum lipids in 75 pairs of female twins using path analysis and maximum-likelihood model fitting. Associations between systolic blood pressure and total cholesterol (r = 0.44, P < 0.001), and LDL-C (r = 0.38, P < 0.001), but not HDL-C (r = 0.05, N.S.), remained significant after age and body mass index adjustment. Univariate models suggested genetic effects contributed 60-70% to the variance of total cholesterol, LDL-C, HDL-C and systolic blood pressure. The remaining variance was explained by age and/or unique environmental influences. Using bivariate models, we demonstrated genetic (P = 0.017) and unique environmental covariance (P = 0.011) of cholesterol and systolic blood pressure. Significant genetic covariance (P = 0.038) was observed between LDL-C and systolic blood pressure. The association between blood pressure and total cholesterol in these twins results from shared genetic and similar unique environmental influences. The association between LDL-C and blood pressure is partly due to shared genetic influences. We conclude that both additive genetic and environmental factors unique to the individual are important determinants of the relationships between serum lipids and blood pressure.

Adolescent↗
PubMed1993

The combined effects of aerobic exercise and alcohol restriction on blood pressure and serum lipids: a two-way factorial study in sedentary men.

OBJECTIVES: To determine whether vigorous exercise and alcohol restriction have additive and independent effects in reducing blood pressure in sedentary male alcohol drinkers. Also to assess whether 4 weeks of vigorous exercise could offset the fall in high-density lipoprotein cholesterol (HDL-cholesterol) usually observed after alcohol restriction. DESIGN: Seventy-five sedentary men were randomly assigned to drink low-alcohol beer or continue their normal drinking habits. Within these two groups subjects were further assigned either to a vigorous exercise programme of three 30-min sessions a week of cycling at 60-70% of maximum workload or to a control light-exercise programme. RESULTS: Seventy-two subjects completed the trial. Alcohol consumption fell by 85% in the low-alcohol group. Fitness increased by 10% following vigorous exercise, with a significant improvement in maximum oxygen uptake. After adjustment for weight loss, a significant effect of alcohol restriction in reducing both systolic and diastolic blood pressure was demonstrated. There was no effect of vigorous exercise on blood pressure. Serum total cholesterol, low-density lipoprotein cholesterol and apolipoprotein B were not influenced by alcohol restriction or vigorous exercise. However, alcohol restriction significantly reduced triglyceride, HDL-cholesterol, its subfractions HDL2-cholesterol and HDL3-cholesterol, and its major apolipoproteins apo A-I and apo A-II. These reductions were unaffected by moderate exercise. CONCLUSIONS: This study provides further evidence that alcohol restriction results in reductions in blood pressure in men who are regular alcohol drinkers. However, a simultaneous increase in fitness did not lead to lower blood pressures than those achieved with alcohol restriction alone, and was unable to offset alcohol-related falls in HDL-cholesterol, its subfractions and its major apolipoproteins.

Adult↗
PubMed1993

Genetic influences on plasma catecholamines in human twins.

We examined the relative genetic and environmental influences on the variability in plasma epinephrine, norepinephrine, and dopamine levels in 109 twin pairs. Epinephrine levels were lower in females (P = 0.048). The norepinephrine concentration increased with age (r = 0.40; P < 0.001). Blood pressure (BP) was not associated with epinephrine levels in either sex or with norepinephrine levels in females. In males, there was a positive association between norepinephrine concentration and diastolic BP (r = 0.31; P = 0.020). A negative association between dopamine levels and systolic and diastolic BP in females (r = -0.22; P = 0.014 and r = -0.20; P = 0.027, respectively) was not maintained after accounting for age, body mass index, and sex. Using path analysis and maximum likelihood model fitting, genetic, unique environment, and age effects contributed 57% (P < or = 0.001), 27% (P < or = 0.001), and 16% (P < or = 0.001) to the variability in norepinephrine, respectively. Genetic effects explained 64% (P < 0.1) and 74% (P < 0.1) of the variability in epinephrine concentrations in females and males, respectively. Unique environmental influences explained the remainder. Genetic and unique environmental effects explained 72% (P < 0.01) and 28% (P < or = 0.001) of the variability in dopamine levels. These results indicate a substantial genetic influence on plasma catecholamine levels. Although consistent associations between plasma catecholamines and BP were not evident in this study, the observed genetic influence on circulating catecholamines may be relevant to the potential role of the sympathetic nervous system in the early stages of essential hypertension.

Adolescent↗
PubMed1993

Alcohol, hypertension and cardiovascular disease--implications for management.

Regular alcohol consumption raises blood pressure and in drinking populations contributes significantly to the prevalence of hypertension. The effect of alcohol is additive to that of obesity. Reduction in alcohol intake leads to a lowering of blood pressure over 1-4 weeks. Acute alcohol ingestion in the evening may lower blood pressures overnight. Heavy weekend drinking may lead to a pressor effect for the succeeding 3 to 4 days. Certain personality types or heavy job strain increase susceptibility to pressor effects of alcohol. Alcohol consumption in the range of 1-3 standard drinks a day appears to have a protective effect against coronary disease and ischaemic stroke, which may be greater in those with a higher risk of vascular disease. At higher levels of consumption the risks of haemorrhagic stroke, cardiomyopathy and hypertension deaths predominate. Moderation of alcohol consumption to no more than two standard drinks a day can be an effective means of improving blood pressure control reducing drug requirements in treated hypertensives, and avoiding drugs in mild hypertensives. Moderating alcohol and reducing excess weight have additive effects in reducing overall cardiovascular risk.

Adult↗
PubMed1992

Association of lifestyle and personality characteristics with blood pressure and hypertension: a cross-sectional study in the elderly.

The association between certain lifestyle and personality characteristics and blood pressure in the elderly was assessed in a cross-sectional study of 843 independent living 60-87 year old volunteers. They comprised 338 women and 505 men of whom 35 and 30% respectively were being treated with antihypertensive drugs. Among untreated volunteers, 28% of women and 28% of men had systolic blood pressure greater than 160 or diastolic blood pressure greater than 95. Isolated systolic hypertension was found in 20% of untreated women and 14% of untreated men. Lifestyle factors and personality characteristics associated with blood pressure were similar to those described in younger adult populations, although there were some differences related to gender and whether subjects were being treated for hypertension. Stepwise multiple regression showed that higher blood pressure was associated with greater body mass index (BMI), alcohol intake and coffee drinking and measures of irritability. Increased physical activity, and high values for measures of suspicion and extraversion were negatively related to blood pressure. Age was positively related to systolic, but not to diastolic blood pressure. The presence of hypertension was significantly associated with self-reports of raised cholesterol, diabetes or angina, as well as past history of heart failure, heart attack or stroke. Thus, in this elderly free-living population blood pressures are still significantly associated with behavioural characteristics which could be further investigated as an alternative or adjunct to antihypertensive therapy.

Aged↗
PubMed1992

Platelet cytosolic free calcium concentration, total plasma calcium concentration and blood pressure in human twins: a genetic analysis.

1. We used path analysis and maximum-likelihood model fitting to evaluate the relative contributions of genetic and environmental factors to the relationships observed between level of blood pressure and both total plasma calcium concentration and platelet cytosolic free calcium concentration in 109 twin pairs. 2. Total plasma calcium concentration was positively associated with systolic (r = 0.26, P less than 0.001) but not diastolic blood pressure, a relationship which remained significant after adjustment for albumin, age and body mass index. A relationship between platelet cytosolic free calcium concentration and both systolic and diastolic blood pressure (r = 0.17 and r = 0.13, respectively, P less than or equal to 0.05) was no longer significant after adjustment for age and body mass index. 3. Additive genetic influences, unique environmental effects and age contributed to 60%, 30% and 10% of the variance in systolic blood pressure, respectively. Additive genetic effects explained 78% of the variance in plasma total calcium concentration and at least 48% of the variance in platelet cytosolic free calcium concentration in females and 37% in males. 4. Bivariate factor models provided evidence of genetic, but not environmental, co-variation of total plasma calcium concentration and systolic blood pressure, suggesting that a common genetic factor (or factors) contributes to their univariate relationship. In contrast, there was evidence of environmental, but not genetic, covariation of platelet cytosolic free calcium concentration and systolic blood pressure, suggesting that some of the individual experiences specific to each twin may be causing these two traits to vary together. 5. The possible confounding effects of adiposity and environmental factors should be considered in future studies investigating the role of intracellular calcium levels in the pathogenesis of hypertension.

Adolescent↗
PubMed1992

Effects of alcohol and caloric restrictions on blood pressure and serum lipids in overweight men.

We have examined the independent and combined effects on blood pressure and blood lipids of alcohol restriction and weight loss in overweight male drinkers with a view to assessing overall effects on cardiovascular risk of two widely promoted nonpharmacological approaches for hypertension. Eighty-six men with a mean age of 44.3 years, a mean regular alcohol intake of 440 ml/wk (five or six standard drinks per day), a mean blood pressure of 137.4 mm Hg systolic and 84.8 mm Hg diastolic, and a mean body mass of 92.5 kg entered a controlled two-way factorial study. The subjects were randomly assigned to four groups for an 18-week intervention in which members of two groups drank only low-alcohol beer, thereby reducing their alcohol intake by 374 ml/wk, while those of the other two groups continued their normal alcohol intake. Within the low and normal alcohol intake groups subjects either continued their usual diet or reduced their caloric intake by 4,200-6,300 kJ/day (1,000-1,500 kcal/day) (with protein, fat, and carbohydrate provided as 15%, 30%, and 55% of total calories, respectively). Calorie reduction and alcohol restriction caused weight losses of 7.5 (p less than 0.001) and 2.1 (p less than 0.01) kg, respectively. Calorie reduction and alcohol restriction were associated with decreases in systolic blood pressure of 5.4 (p less than 0.001) and 4.8 (p less than 0.01) mm Hg, respectively, and in diastolic blood pressure of 4.2 (p less than 0.001) and 3.3 (p less than 0.01) mm Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Alcohol and hypertension.

The relationship between regular alcohol consumption and blood pressure elevation is now firmly established. Outstanding issues which will be discussed relate to the nature of the dose response curve, interactions between alcohol and other dietary and behavioural factors, mechanisms involved and the question of any protective influence of alcohol on atherosclerotic and ischaemic cardiovascular disease associated with hypertension. Alcohol is an important contributory to the prevalence of hypertension, and resistance to drug therapy in drinking communities. Heavy drinking and binge drinking increases the risk of stroke.

Adult↗
PubMed1992

Changes in markers of alcohol intake in man below 'safe' drinking levels.

In a group of 343 working men, only 34 of whom regularly drank more than 60 ml of ethanol per day, logistic regression was used to determine the combination of biomarkers which best discriminated between those who regularly drank less than 30 ml or 30 ml or more of ethanol daily. The index consisted of apolipoprotein A-II, uric acid, gamma-glutamyl transpeptidase and mean corpuscular volume. Even with the relatively low level of alcohol intake reported in these subjects (assessed using a 7-day retrospective alcohol diary), the groups with higher or lower intake of alcohol were separated with a sensitivity of 68%, a specificity of 74% and a positive predictive value of 71%. Systolic blood pressure, adjusted for age and body mass index, was also linearly related to alcohol intake, and when included in the biomarker index improved the proportion correctly classified from 71% to 75%. Using the biomarkers only, 94% of subjects regularly drinking at least 80 ml of ethanol equivalent per day and 100% of the non-drinkers were correctly classified.

Adult↗
PubMed1992

Postural fall in blood pressure in the elderly in relation to drug treatment and other lifestyle factors.

In a study of 843 independent-living men and women aged between 60 and 87 in Perth, Western Australia, stepwise multiple regression, after correction for initial levels of systolic blood pressure, showed that postural fall in systolic blood pressure was positively related to alcohol intake of more than 20 ml/day, the use of sleeping tablets and higher levels of anxiety on the Spielberger state-trait scale, and negatively related to body mass index. Postural fall in blood pressure was not significantly related to treatment for hypertension, age, sex, patterns of usual physical activity, tea or coffee drinking, or the diagnosis of diabetes mellitus. This analysis is the first to examine the relationship between lifestyle factors and the magnitude of the fall in systolic blood pressure on standing after adjustment for the association between the change in a variable and its initial level. Our analysis suggests the need for further study of the possible role of lifestyle factors such as the use of sleeping tablets and alcohol in postural hypotension in the elderly.

Aged↗
PubMed1991

Effects of alcohol intake on plasma fatty acids assessed independently of diet and smoking habits.

1. This study was designed to determine prospectively whether changing alcohol consumption influenced the proportion of plasma linoleic acid independently of diet or smoking habits, and to evaluate changes in the plasma linoleic acid concentration as a potential marker of changes in alcohol consumption. 2. Fasting plasma fatty acid profiles were investigated in 72 male drinkers who were randomly assigned to drink low-alcohol beer or to maintain their usual drinking habits for a period of 4 weeks. 3. At entry to the study, a higher alcohol intake was associated with lower proportions of plasma linoleic acid, arachidonic acid and dihomolinolenic acid and higher proportions of plasma palmitoleic acid, independently of changes in body mass index. Smoking habits were unchanged and there were no major changes in diet during the period of the intervention. 4. Because the plasma palmitoleic acid concentration has been suggested as a possible marker of 'at risk' drinking, we investigated plasma fatty acid concentrations as indicators of alcohol intake. The plasma palmitoleic acid concentration was not a useful discriminator. Indices determined using logistic regression and combining plasma apolipoprotein A-II and linoleic acid concentrations gave better discrimination than either variable alone.

Adult↗
PubMed1991

A double-blind placebo-controlled trial of the effects of short-term potassium supplementation on blood pressure and atrial natriuretic peptide in normotensive women.

To determine the early effect of potassium loading on blood pressure regulatory mechanisms, the effect of 4 days' supplementation with 80 mmol/day KCl on blood pressure and vasodilator hormone release was examined using a double-blind crossover design in normotensive women with a baseline potassium excretion of 51.8 +/- 2.7 mmol/day. Systolic blood pressure fell 1.7 +/- 0.6 mm Hg, (P less than .01) in association with a mean increase in sodium excretion of 14.7 +/- 4.5 mmol/day and an increase in urine volume of 122.6 +/- 57.0 mL/day. There was a small but significant fall in plasma atrial natriuretic peptide (ANP) over the 4 days of potassium supplementation, while significant increases were seen in the levels of plasma potassium (P less than .01) and aldosterone (P less than .01). After 4 days of KCl, urinary 6-keto-PGF1 alpha was significantly elevated and correlated positively with urinary sodium excretion. Plasma renin activity was unchanged. The results suggest that increased vasodilator prostanoid synthesis and a mild natriuresis may contribute to the transient fall in systolic blood pressure. The increase in aldosterone and reduction in ANP probably represent homeostatic responses to this natriuresis, and could account for the failure of potassium supplementation to induce a long-term reduction in blood pressure in other studies in normotensive subjects.

6-Ketoprostaglandin F1 alpha↗