Biomedical subjects

E J De Geus

Publications and source records attributed to E J De Geus.

7 recordsLinked to original sources

PubMed2001

Evidence for genetic factors explaining the association between birth weight and low-density lipoprotein cholesterol and possible intrauterine factors influencing the association between birth weight and high-density lipoprotein cholesterol: analysis in twins.

Recent studies have demonstrated an association between low weight at birth and an atherogenic lipid profile in later life. To examine the influences of intrauterine and genetic factors, we investigated 53 dizygotic and 61 monozygotic adolescent twin pairs. Regression analysis demonstrated that low birth weight was associated with high levels of total cholesterol, low-density lipoprotein (LDL) cholesterol and apolipoprotein B (-0.17 mmol/liter per kg, P = 0.07; -0.18 mmol/liter per kg, P = 0.04; and -0.07 g/liter per kg, P = 0.02, respectively) and with low levels of high-density lipoprotein (HDL) cholesterol (+0.04 mmol/liter per kg, P = 0.1), after adjustment for age, sex, and body mass index. Intrapair differences in birth weight were significantly associated with differences in total cholesterol, LDL cholesterol, and apolipoprotein B in dizygotic twins after adjustment for differences in current body mass index (-0.49 mmol/liter per kg, P = 0.02; -0.51 mmol/liter per kg, P = 0.01; and -0.10 g/liter per kg, P = 0.04, respectively), demonstrating that the larger the difference in birth weight, the higher these risk factors in the twin with the lower birth weight, compared with the cotwin with the higher birth weight. In monozygotic twins, however, the associations between intrapair differences in birth weight and differences in total cholesterol, LDL cholesterol, and apolipoprotein B were in the opposite direction (+0.32 mmol/liter per kg, P = 0.03; +0.23 mmol/liter per kg, P = 0.08; and +0.06 g/liter per kg, P = 0.04, respectively). The association between intrapair differences in birth weight and differences in HDL cholesterol was not significant in dizygotic twins (+0.04 mmol/liter per kg, P = 0.6) and of borderline significance in monozygotic twins (+0.11 mmol/liter per kg, P = 0.05). These data suggest that genetic factors account for the association of low birth weight with high levels of total cholesterol, LDL cholesterol, and apolipoprotein B, whereas intrauterine factors possibly play a role in the association between birth weight and HDL cholesterol.

Adult↗

PubMed2000

Waist circumference and VO2max are associated with metabolic and hemostatic risk in premenopausal nurses.

In 21 nurses (34.4+/-3.9 yr), VO2max physical activity, body composition and lifestyle parameters were measured to determine which of these characteristics are related to metabolic and hemostatic risk for cardiovascular disease. Physical activity was assessed with the 7-day recall interview. VO2max was measured in a progressive and continuous treadmill test to volitional fatigue. Fasting insulin, total cholesterol, HDL-C, triglycerides, fibrinogen, tPA-act, tPA-ag, and PAI-1-ag were determined from fasting blood samples. Contrary to our expectation, there was no association of physical activity with any of these risk indicators. High VO2max was associated with lower levels of insulin and fibrinogen. Regression analyses indicated that metabolic and hemostatic risk indicators, as measured in healthy premenopausal nurses, were mainly predicted by waist circumference and oral contraceptive use.

Adult↗

PubMed2000

Job strain and risk indicators for cardiovascular disease in young female nurses.

This study examined the possible effects of job demands, decision latitude, and job-related social support on risk indicators for cardiovascular disease (CVD) in 165 female nurses. Job strain was measured with the Job Content Questionnaire; CVD risk was measured with insulin, total cholesterol, triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), fibrinogen, tissue-type plasminogen activator (tPA) antigen, tPA activity, plasminogen activator inhibitor-1 antigen, and blood pressure. Multivariate analysis of covariance and regression analyses revealed no effects of either job strain or social support on these risk indicators. All risk indicators deteriorated with age and body mass index. Oral contraceptive use improved fibrinolytic potential and increased HDL-C but had adverse effects on TG levels. Results suggest that in healthy young women job strain is not associated with an unfavorable metabolic or fibrinolytic risk profile.

Adult↗

PubMed2000

Twin-singleton differences in intelligence?

The twin method has been criticised for its alleged non-generalisability. When population parameters of intellectual abilities are estimated from a twin sample, critics point to the twin-singleton differences in intrauterine and family environments. These differences are suggested to lead to suboptimal cognitive development in twins. Although previous studies have reported twin-singleton differences in intelligence, these studies had two major drawbacks: they tested young twins, and twins were compared with (genetically) unrelated singletons. To test accurately whether twin-singleton differences in intelligence exist, a group of adult twins and their non-twin siblings were administered the Dutch WAIS-III. The group was large enough to detect twin-singleton differences of magnitudes reported in earlier investigations. The data were analysed using maximum likelihood model fitting. No evidence of differences between adult twins and their non-twin siblings on cognitive performance was found. It is concluded that twin studies provide reliable estimates of heritabilities of intellectual abilities which can be generalised to the singleton population.

Adult↗

PubMed1997

Heritability of respiratory sinus arrhythmia: dependency on task and respiration rate.

In this study, we investigated the genetic and environmental origin of individual differences in respiratory sinus arrhythmia (RSA) during rest and during four stress tasks. We used a multivariate model including age, RSA, and respiration rate. Participants were 208 male and female pairs of middle-aged twins. A model without sex differences, specifying additive genetic and unique environmental factors, showed the best fit across all conditions. Heritability of RSA ranged from 28% to 43%. Correction for respiration rate yielded RSA heritabilities of similar size. The covariance between respiration rate and RSA was best explained by a combination of correlated unique environmental and correlated additive genetic factors. Combined with data from an earlier project, RSA from 317 adolescent and 712 middle-aged individuals of both sexes was available. This large data set showed that (a) sex differences in mean RSA are absent and (b) RSA decreases considerably from adolescence (111.5 ms) to middle age (60.0 ms).

Adolescent↗

PubMed1996

Genetic architecture of EEG power spectra in early life.

We measured the electroencephalogram (EEG) in 209 5 year old monozygotic (MZ) and dizygotic (DZ) twin pairs to estimate the relative contribution of genetic and environmental factors to EEG power spectra in early life. Data from same-sex and from opposite-sex twin pairs were used to test for sex differences in genetic influences. Results showed high concordance for EEGs of MZ twins for absolute and relative power in delta, theta, alpha 1, alpha 2, beta 1 and beta 2 bands. A model with additive genetic and unique environmental influences explained individual differences in both absolute and relative power in almost all bands and all electrode positions. Heritability of EEG power spectra was high. For absolute power the highest heritabilities were observed in theta, alpha 1, alpha 2 and beta 1 power bands (mean heritability 81, 81, 78, and 73%, respectively). Somewhat lower heritabilities were found in delta and beta 2 bands (mean heritability 55 and 64%, respectively). For relative power heritabilities were 63, 76, 71, 72, 68, and 65 for delta, theta, alpha 1, alpha 2, beta 1, and beta 2, respectively. Virtually no sex differences in heritability were found. These findings indicate that the background EEG is one of the most heritable characteristics in early life.

Brain↗

PubMed1996

Ambulatory monitoring of the impedance cardiogram.

The growing need for more advanced ambulatory monitoring has led to the development of an ambulatory monitor for impedance cardiography (VU-AMD). This paper presents two studies addressing the validity of the VU-AMD. In the first study, the cardiovascular responses of 25 subjects during various conditions were simultaneously recorded with the VU-AMD and a standard laboratory impedance device. Correlations between the responses of the ambulatory and laboratory devices were high, both inter- and intraindividually, except for stroke volume and cardiac output during exercise. In the second study, 26 subjects underwent 24-hr monitoring with the VU-AMD. The values obtained with the VU-AMD were realistic and varied in a predictable way over activity and posture. It is concluded that the VU-AMD is a valid device for the measurement of systolic time intervals in real-life situations, but its applicability for absolute stroke volume and cardiac output determination remains to be established.

Adult↗