Biomedical subjects

L J Beilin

Publications and source records attributed to L J Beilin.

At least 19 recordsLinked to original sources

PubMed1992

Low density lipoprotein composition and oxidizability in coronary disease--apparent favourable effect of beta blockers.

The oxidative modification of LDL in vivo may have an important role in atherogenesis. To determine whether LDL fatty acid, anti-oxidant composition and sensitivity to oxidation in vitro is different in subjects with established atherosclerosis we compared 20 men with angiogram proven coronary disease with 25 controls without clinical evidence of arterial disease. LDL-cholesterol, total triglycerides and LDL fatty acid composition did not differ significantly between the groups. LDL oxidation lag time and oxidation rate in coronary patients (132 min, 0.02 absorbance units/min) and controls (140, 0.017) were not significantly different. However coronary disease subjects taking beta-blockers had evidence for reduced LDL oxidizability (lag time 148 +/- 7 min; oxidation rate 0.017 +/- 0.002 abs units/min) compared with those not on beta-blockers (lag time 114 +/- 7 min, rate 0.025 +/- 0.003, P < 0.005). LDL beta-carotene was significantly lower in coronary patients (0.92 mumol/mmol LDL cholesterol; controls 1.58; P = 0.001). LDL alpha-tocopherol appeared lower in coronary patients (2.8 mumol/mmol LDL cholesterol; controls 3.3; P = 0.056) and was significantly lower in smokers (2.56; non-smokers 3.24; P = 0.04). LDL oxidation rate was negatively correlated with LDL alpha-tocopherol (r = -0.51, P = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

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

A factorial study of salt restriction and a low-fat/high-fibre diet in hypertensive subjects.

OBJECTIVE: To compare the independent and additive effects of sodium restriction and a low-fat, high polyunsaturated: saturated fatty acids (P:S) ratio, high-fibre diet upon blood pressure. DESIGN: A randomized, parallet, double-blind, placebo-controlled (for sodium) 2 x 2 factorial trial. SETTING: Clinical. PARTICIPANTS: Ninety-five hypertensive subjects (mean blood pressure, 137/83 mmHg), mean age 53.5 years, consuming less than 30 ml ethanol/day were selected from community volunteers. Seventy-nine treated and twelve untreated hypertensives completed the trial. INTERVENTION: Subjects followed either a low-sodium, low-fat/high-fibre diet (less than 60 mmol sodium/day; 30% fat energy; P:S ratio = 1; 30-50 g fibre/day) or a low-sodium, normal-fat/normal-fibre diet (less than 60 mmol sodium/day; 40% fat energy; P:S ratio = 0.3; 15 g fibre/day) for 8 weeks. Half of each group received 100 mmol/day NaCl and the remainder received placebo. MAIN OUTCOME MEASURES: Blood pressure and blood lipids. RESULTS: Sodium restriction significantly reduced standing and supine systolic blood pressure, with no effect upon diastolic blood pressure. The low-fat/high-fibre diet had no effect upon blood pressure, but significantly reduced total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. CONCLUSIONS: Sodium restriction reduced blood pressure and did not raise low-density lipoprotein cholesterol. A low-fat/high-fibre diet did not reduce blood pressure but lowered cholesterol levels. A combination of the two regimes has the greater potential for reducing cardiovascular risk in hypertensives.

Adult↗

PubMed1992

Fish oil feeding selectively attenuates contractile responses to noradrenaline and electrical stimulation in the perfused mesenteric resistance vessels of spontaneously hypertensive rats.

1. The mechanism of the antihypertensive effects of n-3 fatty acids were examined in spontaneously hypertensive rats (SHR) by feeding 'Max EPA' fish oil or hydrogenated coconut oil and determining the responses of perfused mesenteric resistance vessels to various contractile agents and peri-arterial nerve stimulation. 2. Fish oil feeding for 4 weeks caused a decrease in the responses to exogenous noradrenaline and electrical nerve stimulations but had no significant effect on vasopressin and KCl (80 mmol/L) induced contractions. 3. These results provide direct evidence for specific attenuation of vascular responses to sympatho-adrenal stimulation in resistance vessels following fish oil feeding and may account for the antihypertensive effects seen in humans and in some forms of hypertension in rats.

Animals↗

PubMed1992

Study of mechanisms of glucocorticoid hypertension in rats: endothelial related changes and their amelioration by dietary fish oils.

1. To investigate possible mechanisms of increased systolic blood pressure after 1 weeks treatment with dexamethasone and its amelioration by fish oil feeding, we have examined the reactivity of aortic rings and perfused mesenteric resistance vessels. 2. Thirty six Sprague-Dawley rats were initially divided into two groups and fed a semisynthetic diet containing either (10% by weight) hydrogenated coconut oil and safflower oil mixture (HCO/S) (24 rats) or fish oil (12 rats) for 5 weeks. From the end of the fourth week, dexamethasone (1.25 mg ml-1) in drinking water, was given to half the rats on hydrogenated coconut oil (HCO/S+Dex) and to the fish oil-fed group (fish oil+Dex). 3. One week of dexamethasone treatment raised systolic blood pressure in the HCO/S+Dex rats but not in the fish oil+Dex group. 4. Endothelium-dependent relaxation to acetylcholine (ACh) was decreased in aortic rings taken from HCO/S+Dex rats compared to rats on HCO/S alone. Relaxant responses to ACh of aortic rings from rats given fish oil+Dex were intermediate between the three groups. Aortic endothelium-independent responses to sodium nitroprusside (SNP) were unchanged between the groups, while aortic contractile responses to noradrenaline were similar in all the groups. 5. In the perfused mesenteric resistance artery, sensitivity to noradrenaline was decreased in rats given fish oil and dexamethasone compared to the other two groups. There were no differences in resistance vessel relaxation to ACh or SNP between groups. 6. Serum corticosterone levels, used as a marker of dexamethasone absorption, were substantially suppressed in dexamethasone-treated rats but levels were higher in rats on fish oil than on HCO/S diets. 7. We suggest that the glucocorticoid-induced rise in systolic blood pressure may be due in part to decreased aortic compliance as a consequence of impaired endothelium-dependent relaxation and perhaps reduced nitric oxide synthesis. Fish oil feeding may ameliorate this rise in blood pressure through (i) changes in dexamethasone absorption, (ii) decrease in reactivity to noradrenaline of perfused mesenteric resistance arteries, (iii) an increase in endothelium-dependent relaxation to ACh or a combination of these three factors.

6-Ketoprostaglandin F1 alpha↗

PubMed1992

Relationships between blood pressure and measures of dietary energy intake, physical fitness, and physical activity in Australian children aged 11-12 years.

STUDY OBJECTIVE: The aim was to examine associations between blood pressure and dietary energy intake, physical activity, and physical fitness in Australian children. DESIGN: The study was a survey of year 7 children attending schools in metropolitan Perth. SETTING: Survey schools were located in suburbs representative of the range of socioeconomic strata in metropolitan Perth. PARTICIPANTS: Data were obtained on 1311 out of 2045 eligible children (64%). The sample included 681 boys and 630 girls. Mean age was 12.0 (SD 0.4) years. MEASUREMENTS AND MAIN RESULTS: Triplicate blood pressure measurements were obtained using a Dinamap oscillometric recorder. Dietary energy intakes were computed from two week day 24 h records. Physical activity was assessed using questionnaires. Physical fitness was measured using a shuttle run test. Additional measurements included weight, height, and skinfold thickness at four sites. A previous observation of an inverse relationship between diastolic blood pressure and dietary energy intake in boys was confirmed. There was evidence of an inverse relationship in girls but not in boys between blood pressure and physical activity. There was little evidence of relationships between blood pressure and physical fitness. CONCLUSIONS: Compared with weight and body mass index, dietary energy intake and the chosen measures of physical activity and physical fitness are poor predictors of blood pressure in the population studied.

Blood Pressure↗

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

Strategies and difficulties in dietary intervention in myocardial infarction patients.

Randomized controlled trials along with 'within group' studies of patients with symptomatic coronary artery disease suggest that dietary and other lifestyle changes can halt progression of coronary atherosclerosis, induce regression of pre-existing severe lesions, and reduce the severity or frequency of angina. Varying combinations have been tested, including restriction of dietary total, saturated and polyunsaturated fat using lean meat or vegetarian diets, fish oil supplements, smoking cessation, stress management, and exercise training. The relative importance of each of these remains unclear. In patients with recent myocardial infarction high fish diets appeared effective in reducing both ischaemic heart deaths and total death rates over two years, whereas modest changes in dietary saturated fats or fibre had no influence on outcome. These results suggest that a far more active dietary approach is needed for patients with symptomatic coronary disease. Further research is required into the possible complementary role of dietary measures and drug treatment for reversing the disease process and improving outcome, using new techniques for achieving behavioural change.

Animals↗

PubMed1992

Effect of chronic ethanol consumption upon cardiovascular reactivity, heart rate and blood pressure in spontaneously hypertensive and Wistar-Kyoto rats.

OBJECTIVE: Clarification of the effect of chronic ethanol consumption upon cardiovascular reactivity in rats. DESIGN: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) normotensive rats were randomly allocated in groups of 10 to ethanol in tap water [20% (v:v) after the first week or tap water for 7-12 weeks]. METHODS: Intra-arterial blood pressure and heart rate were measured at rest and in response to vibration and noise stress. Vascular reactivity was assessed in isolated paired perfused hindquarters and in mesenteric arterioles in a Mulvany-Halpern myograph. RESULTS: Resting intra-arterial blood pressure but not heart rate was lower in both ethanol-treated groups. The ethanol treatment increased the SHR heart rate response to sudden noise but the WKY response did not increase. Pressor responses to noise were initially greater in the ethanol-treated SHR. The ethanol had no effect upon isolated perfused hindquarter resistance at maximal dilation, dose-response curves in response to noradrenaline or vasopressin, or maximal contractile strength. Isolated mesenteric arterioles showed that ethanol had no effect upon responses to nerve stimulation or upon the 50% effective dose required for a response to noradrenaline or vasopressin. CONCLUSIONS: Ethanol treatment heightened the heart rate reactivity to stress without substantially affecting vascular neuro-effector characteristics in SHR. This is likely to be a central effect, caused by suppression of the central nervous inhibitory systems that influence the heart rate and baroreflex activity in a strain of rat already showing evidence of an impaired ability to modulate the heart rate and blood pressure in response to stress. The small reduction in resting blood pressure may be a consequence of the lower weight in the ethanol-treated rats, and/or may reflect a direct depressing action by the alcohol on vascular and cardiac muscle. These findings are discussed in the context of ethanol-induced hypertension in humans and possible genetic variations in central nervous, cardiac and vascular effects.

Alcoholism↗

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

Blood pressure and body composition in children: importance of allowing for cuff size.

A cross-sectional study of blood pressure (BP) was conducted in a sample of 1312 Australian school children aged 11-12 yrs. In line with current recommendations for the measurement of BP, a cuff of appropriate size was chosen for each subject based on his or her arm circumference. Analyses revealed statistically significant independent relationships between measured BP and cuff size. Observed relationships in the sample between measured BP and body composition variables were substantially affected when BP measurements were adjusted to remove the effect of cuff size. Cuff-associated biases in estimates of relationships between BP and body composition variables may still exist even though cuffs are carefully chosen to suit arms of different circumferences. It would appear that this potential problem is largely unrecognised. Some previous studies of relationships between BP and body composition may have been affected.

Anthropometry↗

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↗

PubMed1992

Dietary salt and risk factors for cardiovascular disease.

Sodium restriction by 50 to 100 mmol/day in populations with intakes averaging 150 to 180 mmol/day would likely lead to a reduction of population mean blood pressures, and less of a tendency for blood pressures to rise with age. Fewer people would require antihypertensive drug therapy, and those who did would require less drugs. The extent of any blood pressure fall would be greatest in the elderly or those with established hypertension. A corresponding reduction in stroke incidence might be anticipated, with less certain effects on coronary deaths and diseases. Other factors, such as weight control, alcohol moderation and increased physical activity, may be of greater importance in preventing hypertension in many populations, while cessation of smoking, control of obesity, increased physical fitness and reduction in dietary saturated fat consumption should probably receive the highest priority in terms of overall reduction in the risk of atheromatous cardiovascular disease. In countries such as Japan, which has a relatively high incidence of stroke and a low incidence of coronary disease, a high sodium intake assumes relatively greater importance, in conjunction with obesity and alcohol, as a risk factor for cerebrovascular disease.

Cardiovascular Diseases↗

PubMed1991

Reflotron cholesterol measurements in 1112 Australian children aged 10-12 years.

OBJECTIVE: To study the distribution of blood cholesterol concentration in a sample of Western Australian schoolchildren. DESIGN: The Reflotron dry-chemistry system (Boehringer Mannheim, Germany) was used to measure cholesterol in finger-prick blood samples obtained from Year 6 children aged 10-12 years attending government schools in metropolitan Perth. Recruitment methods ensured that children from different socioeconomic strata were represented. PARTICIPANTS: For the 1239 children enrolled in Year 6 in 30 government schools, parental consent to participate was obtained for 1144; of these cholesterol concentration was measured in 1112. RESULTS: The measurement method proved practicable and was generally well accepted. Cholesterol levels were somewhat lower than those obtained using a laboratory reference method and a bias, relative to national quality assurance standards, was estimated to be -0.32 mmol/L. Mean cholesterol level in boys (4.28 mmol/L, SD 0.69) was not significantly different from that in girls (4.35 mmol/L, SD 0.72). Allowing for measurement bias, 52% of boys and 57% of girls had cholesterol levels exceeding the National Heart Foundation's designated "desirable" level of 4.5 mmol/L for children. CONCLUSIONS: The distribution of cholesterol levels in Australian children compares unfavourably with distributions in children in countries with low rates of cardiovascular disease and indicates a need for widespread, appropriate diet and lifestyle changes.

Australia↗

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↗