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Biomedical subjects

F J Kok

Publications and source records attributed to F J Kok.

At least 127 records · Page 7Linked to original sources
PubMed1990

Systolic blood pressure and cardiovascular mortality among 13,740 Dutch women.

Prospective data of cardiovascular mortality in relation to the systolic blood pressure of women are scarce, especially when combined with other risk factors. The association between systolic blood pressure and cardiovascular mortality was therefore studied in a 10-year follow-up of a population of 13,740 Dutch women, born between 1911 and 1925 who participated in a population-based breast cancer screening project (the DOM Project). Age-adjusted mortality rates over the 10-year follow-up period suggest a J-shaped pattern of cardiovascular mortality according to level of systolic blood pressure. Age-adjusted total cardiovascular, coronary, and cerebrovascular mortality rate ratios were significantly greater than 1.0 among women with elevated systolic blood pressure. Within categories of other risk factors (obesity index, diabetes mellitus, current smoking, and use of antihypertensive medicines) the age-adjusted cardiovascular rate ratios did not show confounding by any of these variables. A very high increase in cardiovascular mortality was observed among hypertensive diabetic women. This study shows that elevated systolic blood pressure is associated with increased rates of cardiovascular mortality for women in this age group.

Body Mass Index↗
PubMed1990

Iron status in the acute phase and six weeks after myocardial infarction.

In a case-control study of 84 myocardial infarction patients and 84 population controls we investigated the association between iron status parameters and myocardial infarction during the acute phase and after six weeks. Immediately after the infarction mean ferritin levels were significantly higher, whereas iron levels and iron saturation of transferrin were significantly lower in cases than in controls. Six weeks after the infarction, serum iron levels were still significantly lower in cases than in controls. Neither serum ferritin levels nor serum iron levels did show a clear association with the size of the ischemic tissue damage as estimated by creatine phosphokinase levels. Our results indicate that serum ferritin and iron levels are influenced by the traumatic effects of the myocardial infarction. Possibly, these transient changes are an acute effect, as seen in infections. An increased uptake of iron in the reticulo-endothelial system for synthesis of ferritin, may account for the lowered serum iron level and the iron saturation of transferrin.

Aged↗
PubMed1990

Serum uric acid correlates in elderly men and women with special reference to body composition and dietary intake (Dutch Nutrition Surveillance System).

In 460 apparently healthy Dutch elderly, aged 65-79 years, serum uric acid correlates were studied by linear regression analyses, for men and women separately. Diuretic therapy, total serum cholesterol (women only) and creatinine clearance (in bivariate analysis only) were significantly associated with serum uric acid level. Positive associations of serum uric acid with body weight, body mass index, body fatness (men) and lean body mass (men) were observed, with and without adjustment for diuretic therapy, creatinine clearance and age. Serum uric acid levels, whether adjusted or not for these variables and for body mass index, were positively associated with alcohol intake (men) and consumption of meat and fish (women), and inversely with consumption of bread, margarine and milk products (women). These results indicate that limited medication with diuretics, weight control and restriction of alcohol use may help to prevent hyperuricemia in the elderly.

Aged↗
PubMed1990

Selenium status and cardiovascular risk factors in healthy Dutch subjects.

To provide further insight into the possible role of selenium in cardiovascular disease, we examined the relationship between cardiovascular risk factors, some nutritional parameters, and short- and long-term selenium status. A total of 82 healthy Dutch volunteers, 59 men and 23 women, aged 40-75 years, were studied. Means and standard deviations of selenium parameters were: plasma selenium 106.4 +/- 23.7 micrograms/L, erythrocyte selenium 0.59 +/- 0.19 microgram/g Hb, toenail selenium 0.78 +/- 0.17 ppm, and erythrocyte glutathione peroxidase activity 28.0 +/- 8.1 U/g Hb. No association was found between selenium status and gender, age, serum total-, LDL-, and HDL-cholesterol, systolic and diastolic blood pressure, alcohol intake, and body mass index. A significantly lower plasma selenium level was observed among smokers compared to nonsmokers (101.0 micrograms/L, SE = 3.9 vs 112.0 micrograms/L, SE = 3.6, p = 0.04). A significant negative association was found between erythrocyte selenium and serum levels of vitamin A and ferritin. No relevant relationship was observed between selenium status and serum fatty acid composition, vitamin E, vitamin B6, and iron. Apart from an association between smoking and short-term selenium status, we found no indications that a possible effect of selenium on cardiovascular disease may operate through the known risk factors.

Aged↗
PubMed1990

Dietary fat and the risk of breast cancer.

Age-adjusted dietary fat intake of 133 incident Dutch breast cancer cases was significantly (p less than 0.01) higher than in 289 apparently healthy controls (mean and standard deviation: 102 +/- 36 g and 92 +/- 30 g, respectively). The age-adjusted relative odds of breast cancer showed a positive trend (p less than 0.05) with increasing fat intake. The multivariate adjusted relative odds was 3.5 (95% Cl = 1.6-7.6) for subjects in the highest quintile of fat intake (above 113 g) compared to those in the lowest quintile (below 65 g); this corresponds to a 30% increased risk per 10% of energy derived from fat. The association could not be attributed to energy intake, nor to the degree of saturation of the fat nor to any specific dietary source of fat.

Adolescent↗
PubMed1990

Selenium in diet, blood, and toenails in relation to breast cancer: a case-control study.

The association between breast cancer and selenium, measured in the diet, plasma, erythrocytes, and toenails, was investigated in a case-control study in the Netherlands during 1985-1987. Dietary selenium intake was assessed by a structured dietary history technique among 133 breast cancer cases and 238 population controls. Absolute and energy-adjusted selenium intake and selenium concentrations in plasma, erythrocytes, and toenails were similar in cases and controls. The multivariate adjusted odds ratios of breast cancer for subjects in the lowest quartile compared with the highest quartile were 1.6 (95% confidence interval (CI) 0.8-3.4) for dietary selenium, 2.0 (95% CI 0.9-4.4) for plasma selenium, 0.9 (95% CI 0.4-1.9) for erythrocyte selenium, and 1.1 (95% CI 0.6-2.1) for toenail selenium. No statistically significant trend was observed in the odds ratios for any of the four indicators of selenium. These results do not suggest a substantial association between selenium and breast cancer for both short- and long-term markers of selenium status.

Adult↗
PubMed1990

Cross-sectional versus longitudinal investigations of the diet-cancer relation.

Within a prospective cohort study on diet and cancer, information was collected on cancer prevalence and baseline meat consumption. A nested case-control study on meat and cancer was conducted with 656 prevalent colorectal cases, 1,894 breast cancer cases, and 4,701 controls. When analyzed cross-sectionally, prevalence odds ratios for eating meat rarely versus regularly were 2.08 for female colorectal and 1.75 for breast cancer. In the longitudinal analysis, cases who started consuming meat rarely after diagnosis were excluded, resulting in odds ratios of 0.51 for female colorectal and 1.17 for breast cancer. These opposite findings highlight the problem of cross-sectional designs.

Aged↗
PubMed1989

[A study of the relationship between blood pressure and mineral intake in elderly Dutch subjects].

In a nationwide survey among 530 apparently healthy elderly people, aged 65-79 years, the prevalence of hypertension was 58% in males and 68% in females. About 40% of them had no medical antihypertensive treatment. After exclusion of subjects on antihypertensive medication or on a prescribed diet, the energy, fat, alcohol, potassium and calcium intake, the sodium, potassium, magnesium and calcium excretion in the 24-hour urine and the Quetelet Index of normotensive elderly were compared with those of hypertensive elderly. Hypertensive males had a higher sodium:potassium ratio and a lower potassium:creatinine ratio in the 24-hour urine. Hypertensive females had a higher calcium excretion. No differences were observed between normotensive and hypertensive elderly in the mineral intake, whereas there were some differences in mineral excretions with the urine. The correlations of the mineral excretions with the creatinine clearance proved to be stronger among hypertensives. This might indicate a lower bioavailability and (or) aberrant metabolism of minerals (especially calcium in hypertensive women and potassium in hypertensive men).

Aged↗
PubMed1989

Consumption of fermented milk products and breast cancer: a case-control study in The Netherlands.

In a case-control study in The Netherlands, we observed a significantly lower consumption of fermented milk products (predominantly yogurt and buttermilk) among 133 incident breast cancer cases as compared to 289 population controls (mean +/- SD among users only, 116 +/- 100 versus 157 +/- 144 g/day; P less than 0.01). The age-adjusted odds ratio of daily consumption of 1.5 glasses (greater than or equal to 225 g) of fermented milk versus none was 0.50 (95% confidence interval, 0.23-1.08). When fermented milk was entered as a continuous variable (per g) in either age-adjusted or multivariate analysis, the odds ratio expressed per 225 g was 0.63 (multivariate-adjusted 95% confidence interval, 0.41-0.96). After multivariate adjustment for intake of fat and other confounders, a statistically significant decrease in breast cancer risk was also observed for increasing intake of Gouda cheese. The multivariate-adjusted odds ratio expressed per 60 g of this fermented product was 0.56 (95% confidence interval, 0.33-0.95). For daily intake of milk, no statistically significant differences were observed between cases and controls. These results support the hypothesis that high consumption of fermented milk products may protect against breast cancer.

Animals↗
PubMed1989

[Socioeconomic differences in nutrition and nutritional status in 10-11-year-old boys].

The relation between socio-economic status and food consumption and nutritional status was investigated in boys aged 10-11 yr (n = 125) who participated in a survey in 1987. Based on the parents' education and profession, boys were categorized in three levels of socio-economic status. In the lower socio-economic category (n = 59) body mass index and skinfold thickness are higher (p less than 0.05) than in the highest category (n = 41) and caries is more prevalent (83% vs 51%). In comparison with both higher groups, dairy products, vegetables and fruit are less frequently used in the lower category, and consumption of protein, calcium and riboflavin is lower (p less than 0.05). These results indicate an increased risk of caries and obesity in the lower socio-economic group. The other differences clearly have an unfavourable tendency, but do not indicate directly increased risk of nutritional deficiencies or nutrition-related diseases in the lower socio-economic group.

Child↗
PubMed1989

Increased risk of atherosclerosis in women after the menopause.

An increase in the incidence of cardiovascular disease has generally been observed in postmenopausal women, but there have been few studies of the association between menopausal state and atherosclerosis. In this study 294 premenopausal and 319 postmenopausal women aged 45 to 55 were examined radiographically for calcified deposits in the abdominal aorta, which have been shown to represent intimal atherosclerosis. Aortic atherosclerosis was present in eight (3%) of the premenopausal women and in 38 (12%) of the postmenopausal women. After adjustments for age and other indicators of cardiovascular risk women with a natural menopause had a 3.4 times greater risk of atherosclerosis than premenopausal women (95% confidence interval 1.2 to 9.7; p less than 0.05); women who had had a bilateral oophorectomy had a 5.5 times greater risk (1.9 to 15.8; p less than 0.005). No excess risk of atherosclerosis was observed among women who had had a hysterectomy without removal of both ovaries. These results suggest that when oestrogen production stops, either naturally or after surgery, the risk of atherosclerosis is increased.

Age Factors↗
PubMed1989

Low vitamin B6 status in patients with acute myocardial infarction.

The vitamin B6 status of 84 patients with acute myocardial infarction was compared with that of 84 control subjects. Pyridoxal and pyridoxal 5'-phosphate (PLP) in plasma and erythrocytes, as well as the basal and total potential activity of the PLP-dependent enzyme aspartate aminotransferase in erythrocytes, were measured for a comprehensive assessment of vitamin B6 status. The mean levels of all vitamin B6 indexes (except pyridoxal) were lower in the patients than in the control subjects. The differences were statistically significant, except for erythrocyte PLP and total potential enzyme activity. The adjusted relative odds of a myocardial infarction for subjects in the lowest quartile of plasma PLP was about 5 times higher when compared with those in the highest quartile (relative odds = 5.2, 95% confidence interval = 1.4 to 18.9). Similar findings were found with the other vitamin B6 indexes. No significant association between infarct size, as estimated by creatine kinase level, and the vitamin B6 indexes was observed.

Aspartate Aminotransferases↗
PubMed1989

Decreased selenium levels in acute myocardial infarction.

To study the association between selenium status and the risk of myocardial infarction, we compared plasma, erythrocyte, and toenail selenium levels and the activity of erythrocyte glutathione peroxidase among 84 patients with acute myocardial infarction and 84 population controls. Mean concentrations of all selenium measurements were lower in cases than controls. The differences were statistically significant, except for the plasma selenium level. A positive trend in the risk of acute myocardial infarction from high to low toenail selenium levels was observed, which persisted after adjustment for other risk factors for myocardial infarction. In contrast, erythrocyte glutathione peroxidase activity was significantly higher in cases than controls (31.3 +/- 8.4 U/g of hemoglobin and 28.0 +/- 8.1 U/g of hemoglobin, respectively). Because the toenail selenium level reflects blood levels up to one year before sampling, these findings suggest that a low selenium status was present before the infarction and, thus, may be of etiologic relevance. The higher glutathione peroxidase activity in the cases may be interpreted as a defense against increased oxidant stress either preceding or following the acute event.

Aged↗
PubMed1989

Isolated systolic hypertension in Dutch middle aged and all-cause mortality: a 25-year prospective study.

In the early 1950s, the blood pressure of 3901 Dutch civil servants and their spouses aged 40-65 years was measured in a general health survey. Isolated systolic hypertension (systolic pressure greater than 160 mmHg, diastolic pressure less than 90 mmHg) was observed in 6.3% of the women and 3.0% of the men. The prevalence increased with age and it was more common in women in all age groups. Using logistic regression, with adjustment for potential confounders (age, smoking, serum cholesterol, Quetelet index, alcohol consumption, haemoglobin level, pulse rate and diastolic blood pressure) the association of 15- and 25-year total mortality with isolated systolic hypertension was determined. Compared to normotensive people (systolic pressure less than or equal to 135 mmHg, diastolic pressure less than 90 mmHg), the risk of death from all causes was significantly higher for men with isolated systolic hypertension after 15 and 25 years of follow-up (odds ratio OR = 2.4, 95% confidence interval (CI) 1.2-4.8 and OR = 3.2, 95% CI 1.3-8.0). For women 15-years mortality risk was strongly associated with isolated systolic hypertension (OR = 3.7, 95% CI 1.4-9.7). The increased risk was less pronounced after 25 years of follow-up (OR = 1.7, 95% CI 0.96-3.0). Our results support those of other studies and indicate that isolated systolic hypertension is an important independent risk factor for all-cause mortality. Since isolated systolic hypertension may be an indicator for the early onset of ageing, it is important to study its determinants and to pay more attention to its diagnosis and treatment in middle-aged populations.

Adult↗
PubMed1989

Alcohol dose, frequency and age at first exposure in relation to the risk of breast cancer.

Habitual alcohol consumption, in terms of dose and frequency, average daily intake, as well as drinking alcohol at age 25 were compared between 120 incident breast cancer cases and 164 population controls in The Netherlands. Dietary and lifestyle factors, past and present alcohol consumption were established in 1985-1987 in home interviews. In premenopausal women a protective effect of low alcohol consumption (1-4 g/day) as compared to non-drinkers was suggested. The multivariate adjusted odds ratio (OR) comparing women drinking greater than or equal to 30 g with women drinking 1 to 4 g alcohol daily was 8.5 (95% confidence interval: (Cl) = 1.1-65.1). The OR for a dose of alcohol of greater than or equal to 15 g versus 1-14 g was 4.0 (Cl = 1.0-15.6) and for drinking more versus less than three times a week the OR was 2.8 (Cl = 0.8-9.8). In post-menopausal women no association was observed between recent drinking habits and breast cancer risk. In these women, however, the adjusted OR for drinking alcohol before the age of 25 was 2.4 (Cl = 1.0-5.6). Although causal inference is hampered by the cultural aspects of drinking habits, the results suggest that moderate drinking does not increase risk. Drinking more than 30 g daily or a high dose may enhance risk in premenopausal women. Furthermore, an early start to drinking alcohol may increase the relative risk for breast cancer even beyond menopause.

Adult↗
PubMed1988

Serum copper and zinc and the risk of death from cancer and cardiovascular disease.

To investigate the association of serum copper and zinc with mortality from cancer and cardiovascular disease, the authors performed a case-control analysis of data obtained in a Dutch prospective follow-up study. Cancer (n = 64) and cardiovascular disease (n = 62) deaths and their matched controls were taken from a cohort of 10,532 persons examined in 1975-1978. Trace elements were measured in baseline serum samples, which had been stored during the six to nine years of follow-up. The adjusted risk of death from cancer and cardiovascular disease was about four times higher for subjects in the highest serum copper quintile (greater than 1.43 mg/liter) compared with those with normal levels. The excess mortality observed in subjects with low copper status suggests a U-shaped relation. No significant change in the risk of death from cancer and cardiovascular disease was found for subjects with low or high baseline levels of serum zinc. However, a protective effect of a high zinc status on the risk of cancer and cardiovascular disease is compatible with the data. For definitive conclusions, analysis of larger prospective data sets is recommended.

Aged↗