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Biomedical subjects

R Vandongen

Publications and source records attributed to R Vandongen.

At least 19 recordsLinked to original sources
PubMed1998

A controlled trial of health promotion programs in 11-year-olds using physical activity "enrichment" for higher risk children.

OBJECTIVE: To evaluate the short and long term benefits of a school and home based physical activity "enrichment" program for children at higher risk of cardiovascular disease as identified by cluster analysis. STUDY DESIGN: During two 10-week school terms, 800 11-year-olds took part in a randomized controlled trial with the standard physical activity and nutrition program in six schools, the standard program in a further seven schools but with the addition of physical activity enrichment for higher risk children in those schools, and no program in five control schools. Cluster analysis identifying the 29% or so highest risk children used systolic blood pressure, percent body fat, physical fitness, and blood cholesterol. RESULTS: Fitness improved significantly in program schools, particularly with enrichment in higher risk boys. Substantial improvements persisted 6 months later in girls from program schools. At "Enrichment" schools, cholesterol showed significant benefits in higher risk girls and, 6 months later, in both boys and higher risk girls. Sodium intake and, in girls, subscapular skinfolds were lower in "Enrichment" schools when the program ended, but not 6 months later. CONCLUSION: Two-semester health programs with physical activity enrichment for higher risk children can produce benefits sustained for at least 6 months. Improvements extend to lower risk children exposed indirectly to the enrichment. Attenuation of effects on diet and body composition in the longer-term suggest the need for on-going programs.

Anthropometry↗
PubMed1996

Differences in response to nutrition and fitness education programmes in relation to baseline levels of cardiovascular risk in 10 to 12-year-old children.

OBJECTIVE: To examine associations between children's responses to nutrition and fitness programmes and their baseline levels of cardiovascular risk factors. DESIGN: A randomised controlled trial. SETTING: Primary schools in Perth, Western Australia. PARTICIPANTS: 1147 children aged 10-12 years. INTERVENTIONS: Fitness, fitness+school nutrition, school +home nutrition or home nutrition programmes and a control group. MAIN OUTCOME MEASURES: Blood pressure (BP), cholesterol, nutrient intake, fitness, and body fat. RESULTS: Fall in systolic BP was significantly greater in the higher risk groups with the fitness intervention for boys and the home nutrition intervention for girls. Overall, diastolic BP fell for girls in the fitness intervention with no differences related to cluster membership. Higher risk boys in the fitness intervention showed greater improvement in fitness than the lower risk boys. Fitness improved in girls in the fitness programme but responses did not differ significantly according to cluster membership. Decrease in triceps skinfolds was significantly greater for higher risk boys in the home nutrition group and in higher risk girls except for those receiving the school+home nutrition intervention. Home nutrition programmes were associated with decreased intake of fat and greater intake of fibre in girls in the higher risk group and of sugar in higher risk boys. CONCLUSIONS: The greatest improvement in the higher risk children were associated with fitness and home nutrition programmes. Health education programmes aiming to include higher risk children should focus on these areas.

Adipose Tissue↗
PubMed1995

A controlled evaluation of a fitness and nutrition intervention program on cardiovascular health in 10- to 12-year-old children.

BACKGROUND: Programs to improve cardiovascular health in schoolchildren need careful scientific evaluation. METHOD: In a randomized controlled trial of nutrition and fitness programs over a period of about 9 months, 1,147 10- to 12-year-olds from 30 schools were allocated to one of five health programs: fitness, fitness + school nutrition, school-based nutrition, school + home nutrition, home-based nutrition, or a control group. Nutrient intake, fitness, anthropometry, blood pressure, and blood cholesterol were measured before and after intervention. RESULTS: Fitness increased and diastolic blood pressure and triceps skinfolds decreased significantly for girls in the fitness groups. Baseline consumption of sugar, fat, and fiber was outside national guidelines; blood cholesterol exceeded recommendations in one-third of children. In girls, fat intake decreased significantly in the two home nutrition groups and fiber intake increased in the school + home nutrition and fitness groups. Boys in the fitness, fitness + school nutrition, and school + home nutrition group reduced sugar intake. Change in sugar intake correlated negatively with change in fat intake in both boys and girls. CONCLUSIONS: Teacher-implemented health packages are feasible with minimal training but programs should differ between boys and girls. Fitness programs were more successful than nutrition education particularly in girls. Clearer nutrition messages should prevent reciprocal changes in sugar and fat. For girls, the 3 mm Hg reduction of diastolic blood pressure, less obesity, and increased fitness could translate into a substantial reduction in cardiovascular risk in adult life.

Blood Pressure↗
PubMed1995

Clustering of cardiovascular risk factors in Australian adolescents: association with dietary excesses and deficiencies.

BACKGROUND: Effective cardiovascular disease prevention requires strategies aimed at those children and adolescents most at risk. This study was designed to identify adolescents with clustering of higher levels of cardiovascular risk factors related to diet, blood pressure, fitness, fatness and blood cholesterol. METHODS: A representative sample of 555 schoolchildren aged 15 years from the Perth, Australia metropolitan area, was included in a cross-sectional survey analysing relationships between nutrient intake, fitness, physical activity, percentage of body fat, blood pressure and heart rate. RESULTS: Cluster analysis identified 21.1% of boys and 20.7% of girls with significantly worse risk profiles. Higher cardiovascular risk was associated with both dietary excesses, particularly in fat, cholesterol and sodium intake, and deficiencies of a number of minerals, vitamins and dietary fibre. Socioeconomic status was inversely associated with cardiovascular risk and undernutrition in girls. CONCLUSIONS: The analysis has identified a subgroup of about 21% of 15-year-old schoolchildren who share features of a range of unhealthy lifestyle variables, putting them at substantial risk of cardiovascular disease and other ill health in later life.

Adolescent↗
PubMed1994

Effects of varying dietary fat, fish, and fish oils on blood lipids in a randomized controlled trial in men at risk of heart disease.

This study aimed to determine the effects of incorporating fish with 40%- or 30%-fat diets and the differences in response to fish or fish oil omega 3 fats. Men with high-normal blood pressure and elevated serum cholesterol were randomly allocated to one of seven diets for 12 wk. Fish or fish oil with a 40%-fat diet increased total cholesterol, HDL cholesterol, HDL2 cholesterol, and LDL cholesterol, and reduced triglycerides. The 30%-fat diet alone reduced cholesterol, LDL cholesterol, and HDL cholesterol, with triglycerides unchanged. Fish with the 30%-fat diet reduced cholesterol, LDL cholesterol, and triglycerides and increased HDL2 cholesterol. This study has shown that plasma lipids are affected similarly by fish or fish oil in men consuming a 40%-fat diet. Adverse effects of omega 3 fats on total and LDL cholesterol are reversed by a 30%-fat diet, whereas one daily fish meal substantially lowers triglycerides and reverses the fall in HDL cholesterol that is usual with a low-fat diet.

Adult↗
PubMed1993

Neutrophil platelet-activating factor in normal and hypertensive pregnancy and in pregnancy-induced hypertension.

1. Platelet-activating factor is a phospholipid with potent vasodilator and platelet-activating properties. To test the hypothesis that a generalized change in cellular platelet-activating factor metabolism may be involved in the systemic vasodilatation of normal pregnancy or pregnancy-induced hypertension, we studied platelet-activating factor and eicosanoid synthesis in isolated leucocytes obtained from pregnant women before and after delivery compared with age-matched non-pregnant control subjects. Parallel observations were carried out in age- and gestation-matched women with uncomplicated hypertension in pregnancy and in women with pregnancy-induced hypertension and a further set of normotensive pregnant control subjects. 2. Leucocyte counts were higher in all pregnant groups compared with non-pregnant control subjects. Neutrophil production of platelet-activating factor and metabolites of prostacyclin, prostaglandin E2 and thromboxane in response to calcium ionophore stimulation were all lower in pregnant women compared with non-pregnant control subjects, but returned to similar levels 6 weeks post partum. There was no significant difference between essential hypertensive and normotensive groups. When women with pregnancy-induced hypertension were a priori sub-divided into those with or without proteinuria, subjects with proteinuria showed significantly lower levels of neutrophil platelet-activating factor synthesis. 3. Plasma levels of the platelet-activating factor metabolite (lyso-platelet-activating factor) were also lower in pregnancy, suggesting alterations in the activity of enzymes controlling synthesis or degradation of this phospholipid in pregnancy. In pregnancy-induced hypertension the levels of plasma lyso-platelet-activating factor were higher than in normal pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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

Effects on blood pressure of omega 3 fats in subjects at increased risk of cardiovascular disease.

This study was conducted to compare the effects of omega 3 fatty acids, taken as fish or fish-oil supplements in the setting of a high- or low-fat dietary background, on blood pressure and heart rate in men with moderate cardiovascular risks. One hundred twenty men were randomly allocated to five high-fat (40% of daily energy) and two low-fat (30% of energy) groups to undertaken a 12-week dietary intervention period involving fish, fish oil, or a combination of these. Sodium intake was restricted to less than 90 mmol/d. The five high-fat groups were assigned to take either 6 or 12 fish-oil capsules daily, fish or a combination of fish oil and fish, or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals were devised to provide 1.3 g of eicosapentaenoic acid daily, equivalent to that contained in 6 fish-oil capsules. Subjects were instructed to eat a selection of fish that provided an average of 3.65 g/d (range, 3.2 to 4.1 g/d) of total omega 3 fatty acids. Subjects were seen at regular intervals during the baseline and dietary intervention periods for measurement of weight, blood pressure, heart rate, dietary compliance, urinary electrolyte excretion, platelet phospholipid fatty acids, blood glucose, and insulin concentration. There was a greater fall in both systolic and diastolic blood pressures in subjects allocated fish or fish oil, particularly in the low-fat groups, compared with control subjects. However, there was no significant group effect.(ABSTRACT TRUNCATED AT 250 WORDS)

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↗
PubMed1992

Measurement of ascorbic acid in platelets and its relationship to polymorphonuclear leukocyte levels.

A simplified method for measuring ascorbic acid (AA) concentrations in platelets is described. Platelet ascorbate was determined as the difference in concentrations between platelet rich plasma and platelet free plasma. In 20 healthy individuals concentrations of AA in platelets and polymorphonuclear leukocytes were found to be significantly correlated (r = 0.72, P < 0.01). Measurement of platelet ascorbate may provide an estimate of tissue AA status.

Adult↗
PubMed1992

Enhancement of platelet 12-HETE production in the presence of polymorphonuclear leukocytes during calcium ionophore stimulation.

This study investigates the effect of platelet/neutrophil interactions on eicosanoid production. Human platelets and polymorphonuclear leukocytes (PMNs) were stimulated alone and in combination, with calcium ionophore A23187 and the resulting eicosanoids 12S-hydroxy-(5Z,8Z,10E,14Z)-eicosatetraenoic acid (12-HETE), 12S-heptadecatrienoic acid (HHT), 5S,12R-dihydroxy-(6Z,8E,10E,14Z)-eicosatetraenoi c acid (LTB4) and 5S-hydroxy-(6E,8Z,11Z,14Z)-eicosatetraenoic acid (5-HETE) were measured by HPLC. The addition of PMNs to platelet suspensions caused a 104% increase in 12-HETE, a product of 12-lipoxygenase activity, but had only a modest effect on the cyclooxygenase product HHT (increase of 18%). By using PMNs labelled with [14C]arachidonic acid it was shown that the increases in these platelet eicosanoids could be accounted for by translocation of released arachidonic acid from PMNs to platelets and its subsequent metabolism. The observation that 12-lipoxygenase was about five times more efficient than cyclooxygenase at utilising exogenous arachidonic acid during the platelet/PMN interactions was confirmed in experiments in which platelets were stimulated with A23187 in the presence of [14C]arachidonic acid. Stimulations of platelets with thrombin in the presence of PMNs resulted in a decrease in 12-HETE and HHT levels of 40% and 26%, respectively. The presence of platelets caused a small increase in neutrophil LTB4 output but resulted in a decrease in 5-HETE production of 43% during stimulation with A23187. This study demonstrates complex biochemical interactions between platelets and PMNs during eicosanoid production and provides evidence of a mechanism to explain the large enhancement in 12-HETE production.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Plasma lipid levels and platelet and neutrophil function in patients with vascular disease following fish oil and olive oil supplementation.

This double-blind study was designed to examine and compare the effects of supplementing the existing diet with fish oil or olive oil on lipids and cell function in patients with peripheral vascular disease. Thirty-two patients with symptomatic and angiographically demonstrated peripheral vascular disease were screened, matched, and randomly allocated to take either 15 g/d fish oil or olive oil for 4 weeks. Fish oil reduced serum triglyceride levels by 26%, but increased total cholesterol levels due to a significant increase in both low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein-2 cholesterol (HDL2-C). There was a nonsignificant decrease in HDL3-C levels. Olive oil reduced total cholesterol levels, accountable to a significantly decrease in LDL-C levels. Serum thromboxane B2 (TXB2) levels remained unchanged following fish oil, but were significantly increased by olive oil. Urinary excretion of TXB2 and 6-keto-PGF1 alpha was unaffected by either oil supplement. Platelet aggregation, which was measured in platelet-rich plasma in response to two doses of collagen or platelet-activating factor (PAF), was significantly reduced after fish oil, but was increased by olive oil. Following fish oil, there was a significant increase in eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) levels and a decrease in arachidonic acid content of platelet phospholipids. The platelet fatty acid composition after olive oil was unchanged. Fish oil decreased neutrophil leukotriene B4 (LTB4) generation following calcium ionophore stimulation by 33%, while leukotriene B5 levels increased significantly. Neutrophil PAF production and plasma lyso-PAF were unaffected by either oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
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

Differential effect of aspirin on platelet aggregation in IDDM.

Diabetes mellitus is associated with a high incidence of cardiovascular diseases not directly attributable to hyperlipidemia, smoking, or hypertension, but which in part may be explained by an enhanced tendency to thrombosis due to increased platelet activity. The aim of this study was to evaluate platelet function and compare the effectiveness of the antiplatelet drug aspirin on platelet aggregation in diabetic and nondiabetic subjects. Platelet aggregation and composition were examined in 20 male insulin-dependent diabetes mellitus (IDDM) patients and 20 nondiabetic control subjects matched for age and body mass index. All were normotensive with serum total cholesterol less than 6.5 mM. Although within the clinically acceptable normal range, blood pressure was significantly higher in diabetic patients (130/75 mmHg) than in control subjects (123/70 mmHg) (P less than 0.05). Serum thromboxane B2 and ex vivo aggregation of platelets in response to two doses of the agonists collagen and platelet-activating factor (PAF) were similar to nondiabetic subjects. However, after taking 100 mg/day aspirin for 5 days, platelet aggregation to collagen was reduced by 76% in control subjects compared to 56% in IDDM patients (P less than 0.001). Aspirin treatment also reduced the slope of the aggregation curve and increased the lag time (the period between the addition of collagen and the start of irreversible aggregation) significantly more in control than in diabetic platelets. This difference in platelet aggregation could not be attributed to differences in platelet serotonin or thromboxane A2 secretion, the latter being almost completely suppressed by aspirin in each group. Platelet aggregation to PAF was similar in both groups and was not affected by aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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↗