Biomedical subjects

G H Dahlen

Publications and source records attributed to G H Dahlen.

7 recordsLinked to original sources

PubMed1998

Perceived health modifies the effect of biomedical risk factors in the prediction of acute myocardial infarction. An incident case-control study from northern Sweden.

OBJECTIVES: To assess the importance of biomedical risk factors, social factors and self-reported health in the prediction of the first event of acute myocardial infarction (AMI) in an apparently healthy middle-aged population. DESIGN: An incident case-control study. SETTING: The study was nested within the Västerbotten Intervention Program and the Northern Sweden MONICA cohorts. SUBJECTS: The study consists of 78 AMI cases with two randomly selected controls per case from the same study cohorts. RESULTS: Significant odds ratios were found for history of diabetes, daily smoking, cholesterol, body-mass index, hypertension, lower education and perceived ill health. In multivariate logistic regression smoking, hypertension and cholesterol of > or =7.8 mmol L(-1) remained significant. An interaction was observed between number of biomedical risk factors and perceived health. CONCLUSIONS: Smoking, hypertension and hypercholesterolaemia explain a major share of incident AMI events in a Swedish middle-aged population. The study further illustrates that perceived ill health negatively modifies the impact of these risk factors.

Case-Control Studies↗

PubMed1995

Influence of oral contraceptive use on lipoprotein (a) and other coronary heart disease risk factors.

We have studied the influence of oral contraceptive use on lipoprotein (a) levels in a cohort of women aged 18, 21 and 24 years (n = 559). Data was available on oral contraceptive formulation and dosage, anthropometric variables, exercise, serum lipoprotein (a), insulin, lipid and apolipoprotein levels. Lipoprotein (a) was determined by radioimmunoassay. Differences were assessed with non-parametric statistical methods. Forty per cent of the study women used oral contraceptives. The use of desogestrel-containing monophasic preparations was associated with lower levels of lipoprotein (a) compared to triphasic/levonorgestrel formulations or to non-users (P = 0.005). This effect was seen only in non-smoking women. Oral contraceptive users had higher levels of serum apolipoprotein B, HDL3-cholesterol, apolipoprotein A-I, triglycerides and systolic blood pressure, and lower serum lecithin:cholesterol acyltransferase activity. Lifestyle factors (smoking, exercise) showed no significant influence on lipoprotein levels. In conclusion, the use of desogestrel-containing oral contraceptives has a marked lowering effect on lipoprotein levels. Prospective studies will be needed to assess the net influence of oral contraceptive use on cardiovascular health.

Adolescent↗

PubMed1994

Lipoprotein (a) levels in children and young adults: the influence of physical activity. The Cardiovascular Risk in Young Finns Study.

A high lipoprotein(a) (Lp(a)) level is an independent and predominantly genetically determined risk factor for coronary heart disease and other vascular diseases. We studied the levels of Lp(a) and the influence of physical activity on Lp(a) in the young Finnish population. The study cohort comprised children and young adults aged 9, 12, 15, 18, 21 and 24 years (n = 2464) participating in a large multicenter follow-up study of cardiovascular risk factors in children and young adults. Data were available on physical activity, anthropometric variables, serum Lp(a), insulin and lipid levels. A physical activity index was calculated based on several physical activity variables. Lp(a) was determined by radioimmunoassay with a detection threshold of 3 mg/dl. Differences were assessed with non-parametric statistical analyses. The observed range of Lp(a) was from < 3 to 90.8 mg/dl. The distribution of Lp(a) was highly skewed as 88% of the population (89% males and 87% females) had Lp(a) concentrations less than 25 mg/dl. A total of 35% of the subjects had Lp(a) levels less than 3 mg/dl. There were no significant differences in Lp(a) levels with respect to age or gender. The serum concentration of Lp(a) was statistically significantly correlated with the level of physical activity. Other behavioral variables studied did not have a significant contribution to the variability of Lp(a) levels. These results demonstrate that levels of Lp(a) are not related to age, gender or many of the known coronary heart disease risk factors. However, physical activity is associated with favorable Lp(a) levels, as high levels of Lp(a) (> 25 mg/dl) were less frequent in the physically most active subjects.

Adolescent↗

PubMed1991

Racial (black-white) differences in serum lipoprotein (a) distribution and its relation to parental myocardial infarction in children. Bogalusa Heart Study.

BACKGROUND: The value of lipoprotein (a) [Lp(a)] in the prediction of coronary artery disease risk very early in life remains to be established in different racial groups. METHODS AND RESULTS: Serum Lp(a) distribution and its relation to parental histories of myocardial infarction were examined in 2,438 children (8-17 years old) from a biracial community. Parental myocardial infarction was used as a surrogate measure of future risk of disease in the offspring. Lp(a) levels averaged 1.7-fold higher in blacks than in whites (p less than 0.0001). A small but significant sex difference (females greater than males, p less than 0.05) was seen in both races. Race was the only independent variable that contributed appreciably (9%) to the variability of Lp(a) in serum. White children with parental myocardial infarction (n = 90) had increased levels of Lp(a) compared with those without parental myocardial infarction (22.4 versus 17.1 mg/dl, p less than 0.01). Furthermore, among white children, the prevalence of parental myocardial infarction was higher in those with Lp(a) levels of more than 25 mg/dl than in those with values of 25 mg/dl or less (9.5% versus 5.4%, p less than 0.01). In contrast, the relation of Lp(a) to parental myocardial infarction was not seen in black children. No associations were observed between parental myocardial infarction and serum levels of any of the lipids or lipoprotein cholesterol classes in children of either race. CONCLUSIONS: Serum Lp(a) levels may prove valuable in the assessment of coronary artery disease risk early in life among white populations. These findings also emphasize the need to evaluate the atherogenic potential of Lp(a) in different racial groups.

Adolescent↗

PubMed1986

Association of levels of lipoprotein Lp(a), plasma lipids, and other lipoproteins with coronary artery disease documented by angiography.

In a study of 307 white patients who underwent coronary angiography, the relationship of coronary artery disease (CAD) to plasma levels of lipoprotein Lp(a) and other lipid-lipoprotein variables was examined. Lp(a) resembles low-density lipoprotein (LDL) in several ways, but can be distinguished and quantified by electroimmunoassay. CAD was rated as present or absent and was also represented by a quantitative lesion score derived from estimates of stenosis in four major coronary vessels. Coronary lesion scores significantly correlated with Lp(a), total cholesterol, triglycerides, LDL cholesterol, and high-density lipoprotein (HDL) cholesterol levels by univariate statistical analysis. By multivariate analysis levels of Lp(a) were associated significantly and independently with the presence of CAD (p less than .02), and tended to correlate with lesion scores (p = .06). Among subgroups Lp(a) level was associated with CAD in women of all ages and in men 55 years old or younger. An apparent threshold for coronary risk occurred at Lp(a) lipoprotein mass concentrations of 30 to 40 mg/dl, corresponding to Lp(a) cholesterol concentrations of approximately 10 to 13 mg/dl. Plasma Lp(a) in white patients appears to be a major coronary risk factor with an importance approaching that of the level of LDL or HDL cholesterol.

Cholesterol↗

PubMed1983

Human plasma lipoprotein [a]. Structural properties.

When lipoprotein [a] was isolated in the presence of the proteolytic inhibitor Trasylol, its apoprotein exhibited one dominant band corresponding to a molecular weight of about 1.2 million when analyzed by electrophoresis on 3.25% sodium dodecyl sulfate-polyacrylamide gels. After chemical reduction, this band was missing but was replaced by two bands, one corresponding to a molecular weight of about 490,000 and the other to a molecular weight of about 645,000. Before treatment with reducing agents, the apolipoprotein [a] and apolipoprotein B immunoreactivities were detectable in the same electrophoretic band, but after reduction the apolipoprotein [a] was demonstrated to be separate from the apolipoprotein B. These results suggest that the apoprotein of lipoprotein [a] is composed of two subunits which are similar in molecular weight and are held together by one or more disulfide bonds. One subunit possesses apolipoprotein [a] and the other apolipoprotein B immunoreactivity. The secondary structure of the apoprotein components within lipoprotein [a] has been studied by circular dichroism and found to differ significantly from the secondary structure of the apoproteins in low density lipoproteins and high density lipoproteins. About 30% alpha-helical structure was measured in lipoprotein [a] compared to 48% in low density lipoproteins and 70% in high density lipoproteins. Lipoprotein [a] exhibited a much higher percentage of disordered structure than either of the other two lipoproteins.

Circular Dichroism↗

PubMedDate not supplied

Relationship of plasma lipoprotein Lp(a) levels to race and to apolipoprotein B.

Lipoprotein Lp(a) is an atherogenic subfraction of plasma lipoproteins which has been studied predominantly in white populations. We quantified Lp(a) by electroimmunoassay in plasma from 105 black and 134 white healthy men and women. Results were correlated with clinical variables and plasma levels of lipids, other lipoproteins, and apolipoprotein (apo) B determined by radioimmunoassay. Black subjects had levels of Lp(a) that averaged twice those of whites (p less than 0.001). Among blacks, Lp(a) levels showed a bell-shaped frequency distribution, while among whites the distribution was strongly skewed, with the highest frequencies at low levels. Contrary to previously published results, the apo B levels in our study correlated significantly, though weakly, with Lp(a) (r = 0.21, p = 0.001 among whites, and r = 0.15, p = 0.02 among blacks, Kendall rank correlation). The regression slopes and variances suggested that apo B in the Lp(a) lipoprotein could account for the correlation. Lp(a) levels did not correlate significantly with any other plasma lipoprotein or lipid levels. The implications of this study are as follows: Despite the high levels of Lp(a) among blacks in the Houston area, these blacks do not experience greatly increased atherosclerotic progression and mortality. Thus, the atherogenicity of Lp(a) in blacks must be decreased or counterbalanced by other factors. The correlation between Lp(a) and apo B should be taken into account when analyzing atherogenic risk, but this correlation is not strong enough to dispute the independence of Lp(a) and apo B as risk factors.

Adolescent↗