Biomedical subjects

K H Bønaa

Publications and source records attributed to K H Bønaa.

At least 19 recordsLinked to original sources

PubMed2003

Intra- and interobserver variability in the measurements of abdominal aortic and common iliac artery diameter with computed tomography. The Tromsø study.

OBJECTIVES: to assess intra- and interobserver variability in the measurement of aortic and common iliac artery diameter by means of computed tomography (CT). DESIGN: reproducibility study. MATERIAL AND METHODS: three radiologists performed measurements of aortic diameter at five different levels and of both common iliac arteries with CT. Fifty-nine subjects were examined, 29 with and 30 without abdominal aortic aneurysms (AAA) as assessed by ultrasound. RESULTS: intraobserver variability varied between radiologists, measurement plane (anterior-posterior vs transverse) and measurement level. The interobserver variability was markedly higher at the bifurcation than at the suprarenal level and higher than intraobserver variability for measurements at all levels. Both intraobserver and interobserver variability increased with increasing vessel diameter and were largest in patients with AAA. The absolute intraobserver difference of the maximal infrarenal aortic diameter was 2mm or less in 94% of intraobserver pairs. The corresponding interobserver difference was 82%. CONCLUSIONS: interobserver variability of CT measurements of aortic and common iliac artery diameter is not negligible and should be taken into account when making clinical decisions. When assessing change in aortic diameter, previous CT-scans should be reviewed simultaneously as a routine to exclude interobserver variability.

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PubMed2001

Prevalence of and risk factors for abdominal aortic aneurysms in a population-based study : The Tromsø Study.

In a population-based study of 6,386 men and women aged 25--84 years in Tromsø, Norway, in 1994--1995, the authors assessed the age- and sex-specific distribution of the abdominal aortic diameter and the prevalence of and risk factors for abdominal aortic aneurysm. Renal and infrarenal aortic diameters were measured with ultrasound. The mean infrarenal aortic diameter increased with age. The increase was more pronounced in men than in women. The age-related increase in the median diameter was less than that in the mean diameter. An aneurysm was present in 263 (8.9%) men and 74 (2.2%) women (p < 0.001). The prevalence of abdominal aortic aneurysm increased with age. No person aged less than 48 years was found with an abdominal aortic aneurysm. Persons who had smoked for more than 40 years had an odds ratio of 8.0 for abdominal aortic aneurysm (95% confidence interval: 5.0, 12.6) compared with never smokers. Low serum high density lipoprotein cholesterol was associated with an increased risk for abdominal aortic aneurysm. Other factors associated with abdominal aortic aneurysm were a high level of plasma fibrinogen and a low blood platelet count. Antihypertensive medication (ever use) was significantly associated with abdominal aortic aneurysm, but high systolic blood pressure was a risk factor in women only. This study indicates that risk factors for atherosclerosis are also associated with increased risk for abdominal aortic aneurysm.

Adult↗

PubMed2001

Echolucent plaques are associated with high risk of ischemic cerebrovascular events in carotid stenosis: the tromsø study.

BACKGROUND: The purpose of the study was to assess in a prospective design whether plaque morphology is associated with risk of ischemic stroke and other cerebrovascular events in subjects with carotid stenosis. METHODS AND RESULTS: A total of 223 subjects with carotid stenosis (123 with 35% to 49% degree of stenosis, 100 with 50% to 99% stenosis) and 215 control subjects matched by age and sex who participated in a population health survey at baseline were followed up for 3 years. Plaque echogenicity was assessed by ultrasound at baseline and scored as echolucent, predominantly echolucent, predominantly echogenic, or echogenic. Forty-four subjects experienced >/=1 ischemic cerebrovascular events in the follow-up period. Plaque echogenicity, degree of stenosis, and white blood cell count were independent predictors of cerebrovascular events. The unadjusted relative risk for cerebrovascular events was 13.0 (95% CI 4.5 to 37.4) in subjects with echolucent plaques and 3.7 (95% CI 0.7 to 18.2) in subjects with echogenic plaques when subjects without stenosis were used as the reference. The adjusted relative risk for cerebrovascular events in subjects with echolucent plaques was 4.6 (95% CI 1.1 to 18.9), and there was a significant linear trend (P=0.015) for higher risk with increasing plaque echolucency. The adjusted relative risk for a 10% increase in the degree of stenosis was 1.2 (95% CI 1.04 to 1.4). CONCLUSIONS: Subjects with echolucent atherosclerotic plaques have increased risk of ischemic cerebrovascular events independent of degree of stenosis and cardiovascular risk factors. Subjects at high risk for ischemic vascular events may be identified by ultrasound assessment of plaque morphology.

Aged↗

PubMed2001

Serum lipids and regulation of tissue factor-induced coagulation in middle-aged men.

Formation of an occlusive thrombus by exposure of tissue factor (TF) to circulating blood and subsequent triggering of coagulation by TF-activated factor VII (FVIIa) complexes on ruptured atherosclerotic plaques is thought to be a key event in myocardial infarction. Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of TF-induced coagulation in which the anticoagulant function most probably is restricted to free TFPI in human plasma. The present study was undertaken to assess the interrelations between serum lipids and components of TF-induced coagulation in 234 apparently healthy men aged 36-56 years recruited from the general population. Plasma free TFPI antigen (Ag) was positively correlated (P < .001) with total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, apolipoprotein B (apoB-100), fibrinogen, total amount of FVII (FVIIam), coagulation activity of factor VII (FVIIc), and FVIIa. The significant predictors for free TFPI Ag were total cholesterol, triglycerides, fibrinogen, FVIIc, and age, which explained 33% of the plasma variation in free TFPI Ag assessed by multiple regression analysis. A highly significant (P < .0001) linear trend for increase in atherogenic lipids (i.e., total cholesterol and triglycerides), FVII (i.e., FVIIc and FVIIa), and fibrinogen across quartiles of TFPI Ag was demonstrated after adjustment for confounders. These findings may indicate a compensatory increase in plasma free TFPI with lipid and hemostatic risk factors for atherothrombotic diseases in healthy middle-aged men.

Adult↗

PubMed2001

Age and sex differences in the relationship between inherited and lifestyle risk factors and subclinical carotid atherosclerosis: the Tromsø study.

BACKGROUND: Ultrasound measurement of carotid artery intima-media thickness (IMT) is regarded as a valid index of atherosclerosis. Age and sex differences in the distribution of, and risk factors for, IMT have not been investigated thoroughly. METHODS: In 1994-1995 a total of 6408 men and women aged 25-84 years living in the municipality of Tromsø, Norway, underwent ultrasound examination of carotid artery IMT and measurements of cardiovascular risk factors. RESULTS: Age, systolic blood pressure, total cholesterol, HDL cholesterol, body mass index, and smoking were independent predictors of IMT in both sexes. Fibrinogen levels and physical activity were associated with IMT in men only, whereas triglyceride levels were associated with IMT independently of HDL cholesterol in women only. A family history of cardiovascular disease (CVD) was an independent predictor of IMT in both sexes, also when controlling for traditional CVD risk factors. The magnitude of the association between most risk factors and IMT did not differ depending on age, but the effects of physical activity and triglycerides were more pronounced at higher age. CONCLUSION: These data suggest that there are significant age and sex differences in the distribution and the determinants of subclinical atherosclerosis.

Adult↗

PubMed2001

Determinants of serum calcium in men and women. The Tromsø Study.

The level of serum calcium appears to be associated with blood pressure and metabolic risk factors for cardiovascular disease. Determinants of serum calcium may therefore be of interest. In a health survey in Tromsø in 1994-1995, 27,159 subjects were examined. The survey included measurements of serum calcium and questionnaires on diet and lifestyle factors. In males mean serum calcium declined from 2.41 mmol/l for those in their 20s to 2.34 mmol/l for those in their 80s. In females mean serum calcium was stable at a level of 2.35 mmol/l before the menopause, and thereafter reached a plateau of 2.39 mmol/l. In both sexes serum calcium showed a positive association with body mass index (BMI) and coffee consumption that persisted after correcting for other variables in a multiple regression model (p < 0.05). Physical activity had no significant association with serum calcium. In females alcohol consumption was negatively, and cigarette smoking positively associated with serum calcium (p < 0.01). No significant effect on the serum calcium levels was found for the intake of calcium or vitamin D, except for males with a calcium intake below 200 mg/day. Some of the observed effects, like the variation with age, may partly be explained by alterations in levels of serum albumin to which approximately 40% of circulating calcium is bound and which was not adjusted for in this study, whereas that is hardly the case for the association with BMI and coffee consumption. However, none of these factors could affect the serum calcium level more than 0.02 mmol/l, and the biological significance of the observed associations questionable.

Adult↗

PubMed2001

Prevalence of and risk factors associated with carotid artery stenosis: the Tromsø Study.

BACKGROUND AND PURPOSE: To assess prevalence, distribution, ultrasound characteristics and determinants of carotid artery stenosis in a large, population-based study of both women and men. METHODS: A total of 6,727 persons aged 25-84 years were screened for extracranial stenosis with Duplex ultrasound of the right carotid artery. Risk factors were compared in 225 persons with stenosis and 5,514 persons without. RESULTS: The prevalence of carotid stenosis was higher in men than in women, where 3.8% (95% CI, 3.2-4.6%) had carotid stenosis, compared to 2.7% (95% CI, 2.2-3.3%) in women (p = 0.001). The prevalence gradually increased by age in both genders. Cholesterol, HDL cholesterol, fibrinogen, systolic blood pressure levels and current smoking were independently associated with carotid artery stenosis in both women and men. The presence of carotid stenosis was significantly associated with a history of cerebrovascular disease, coronary heart disease and peripheral artery disease. For each 10% increase in the degree of carotid stenosis, the risk of having had a cerebrovascular event increased by 26%. CONCLUSIONS: The prevalence of carotid stenosis in the general population, as measured by ultrasound, is low. Age, male gender, smoking, total cholesterol, HDL cholesterol (inverse), fibrinogen and systolic blood pressure are all independent predictors of carotid artery stenosis.

Adult↗

PubMed2001

Low levels of high-density lipoprotein cholesterol are associated with echolucent carotid artery plaques: the tromsø study.

BACKGROUND AND PURPOSE: Ultrasound-assessed plaque morphology is an independent predictor of ischemic stroke. The purpose of this population-based cross-sectional nested case-control study was to examine the risk factors associated with carotid plaque morphology. METHODS: Ultrasonography of the right carotid artery was conducted on 6727 participants in a population health survey (response rate 79%). Plaque echogenicity, defined as reflectance of the emitted ultrasound signal, was scored as echolucent, predominantly echolucent, predominantly echogenic, or echogenic. Information on cardiovascular risk factors in all 216 participants who had carotid stenosis and in 223 control subjects matched by age and sex who did not have carotid stenosis was obtained from measurements of blood pressure, weight, height, and nonfasting blood samples and from a self-administered questionnaire. RESULTS: In both univariate and multivariate analyses, low levels of HDL cholesterol and increasing degree of stenosis were independently associated with an increased risk of having an echolucent plaque. For 1-SD increase in HDL cholesterol, the adjusted odds of being in a lower plaque echogenicity category decreased by approximately 30% (OR 0.69, 95% CI 0.52 to 0.93). CONCLUSIONS: These findings indicate that low levels of HDL cholesterol are associated with an increased risk of having echolucent, rupture-prone atherosclerotic plaques.

Adult↗

PubMed2000

Fatty acid chain length and degree of unsaturation are inversely associated with serum triglycerides.

Little is known about the association between dietary fatty acids and serum triglycericle concentrations. Plasma fatty acids may reflect dietary intake and can be used to study the relationship between concentrations of individual fatty acids and serum lipids. We examined the cross-sectional relationship of plasma fatty acids with serum nonfasting triglyceride and total cholesterol concentrations. Relative concentrations of individual plasma phospholipid fatty acids were determined by gas liquid chromatography among 4,158 men aged 40-42 yr, who participated in a population study. The pattern of associations between individual fatty acids and cholesterol was different from that between individual fatty acids and triglyceride concentrations. All fatty acids displayed positive associations with total cholesterol concentration except linoleic acid, which was inversely related to cholesterol. In contrast, associations between individual fatty acids and triglyceride concentrations differed in strength and direction depending on both carbon chain length and the degree of unsaturation. Concentrations of very long chain (20 carbon atoms or more) saturated, monounsaturated, and n-3 polyunsaturated fatty acids showed significant inverse associations with triglycerides, whereas shorter fatty acids within these classes were positively associated with triglyceride concentrations. The present data suggest that the associations between concentrations of serum triglycerides and plasma phospholipid fatty acids depend on both fatty acid chain length and the degree of unsaturation.

Adult↗

PubMed2000

Primary hyperparathyroidism detected in a health screening. The Trømsø study.

Serum calcium was measured in 12,339 men and 13,394 women ages 25 to 75. Primary hyperparathyroidism, defined as a combination of serum calcium and parathyroid hormone (PTH) levels within the extreme or upper normal range, was diagnosed in 17 men and 47 women. The prevalence in both sexes increased with age. When 42 subjects with asymptomatic primary hyperparathyroidism were followed for 3 years, no significant increase in serum calcium or PTH was seen. In a subgroup of 473 men and 517 women ages 50 to 75, serum PTH was measured along with serum calcium. Depending on the criteria used to define primary hyperparathyroidism, the prevalence in older women within this subgroup ranged from 3.6% to 13.9%. The study concluded that a high prevalence of primary hyperparathyroidism exists in older women, although the progression of the disease, judging by serum calcium and PTH measurements, appears to be very slow.

Adult↗

PubMed2000

Population-based study of age at menopause and ultrasound assessed carotid atherosclerosis: The Tromsø Study.

Early menopause has been associated with higher prevalence and incidence of cardiovascular disease and death than late menopause, indicating that early loss of ovarian function and subsequent deficiency of estrogen may promote such diseases. No population-based studies have, however, examined the relation between age at menopause and atherosclerosis. We assessed the prevalence and the extent of carotid atherosclerosis by high-resolution B-mode ultrasound in 2588 postmenopausal women who participated in a population health survey. Information about age at menopause and menarche, parity, use of hormone replacement therapy, and prevalent diseases was collected, and cardiovascular risk factor levels were measured. Women with late menopause and women who ever had used postmenopausal estrogens had significantly less atherosclerosis than women with early menopause and those with never use of estrogen. This study provides further support for the hypothesis that estrogen protects women against cardiovascular disease.

Adult↗

PubMed2000

Sex differences in the relationship of risk factors to subclinical carotid atherosclerosis measured 15 years later : the Tromsø study.

BACKGROUND AND PURPOSE: Ultrasound measurement of carotid artery intima-media thickness (IMT) is regarded as a valid index of atherosclerosis. Determinants of IMT in cross-sectional studies have been established, but the long-term relationship between cardiovascular risk factors and subclinical atherosclerosis has not been investigated thoroughly. METHODS: We included in the study 3128 middle-aged men and women in Tromsø, Norway, who in 1980 attended the baseline examination with measurements of cardiovascular risk factors and who underwent carotid ultrasonography after 15 years of follow-up. RESULTS: Age, blood pressure, total cholesterol, HDL cholesterol, and body mass index were independent long-term predictors of IMT in both men and women. Triglyceride levels were associated with an increase in IMT in women only, while physical activity and smoking were predictors of IMT in men only. However, smoking was associated with increased risk of having atherosclerotic plaque in both men and women. There were no differences in the strength of risk factor effects on IMT in the common carotid artery and the carotid bifurcation. CONCLUSIONS: The present study indicates that established cardiovascular risk factors are independent predictors of subclinical atherosclerosis measured after 15 years of follow-up. However, there may be significant sex differences in the relationship between triglycerides, smoking, and physical activity and the risk of atherosclerosis.

Adult↗

PubMed2000

Relationship between apolipoprotein E polymorphism, postprandial hyperlipemia and hemostatic variables in patients with combined hyperlipemia.

BACKGROUND AND AIM: Combined hyperlipemia is a common lipid abnormality associated with coronary heart disease (CHD). Aim of this study was to investigate the relationship between this abnormality and hemostatic risk factors related to thrombosis. METHODS AND RESULTS: Forty-one patients were examined in the fasting state and during postprandial hyperlipemia. They had high levels of factor VIIc in the fasting state. During postprandial hyperlipemia a highly significant (p < 0.001) increase of activated factor (VIIa) occurred. This activation was not correlated to the increase in free fatty acids, but to the degree of postprandial hypertriglyceridemia. The absolute postprandial triglyceridemia was highest in subjects with the apolipoprotein (apo) E2 allele. Tissue factor pathway inhibitor activity (TFPIa) was correlated to LDL cholesterol and apo B concentrations and was highest in subjects with genotypes containing the E4 allele. CONCLUSIONS: Subjects with combined hyperlipemia may have an increased thrombotic risk related to activation of factor VII during postprandial hyperlipemia. Subjects with genotypes including the apoE4 allele may have a high lipid risk profile associated with high levels of LDL cholesterol.

Adult↗

PubMed1999

Population-based study of the relationship among muscle morphology, insulin action, and hypertension.

To examine whether changes in muscle morphology are linked to the metabolic abnormalities associated with the insulin resistance syndrome, muscle morphology and the metabolic profile were examined in 52 individuals with untreated hypertension (mean arterial pressure [MAP] = 117+/-7 mm Hg) and 38 carefully matched controls (MAP = 89+/-5 mm Hg). Oral glucose tolerance tests and hyperglycemic clamps were performed for measurements of insulin action on glucose disposal and suppression of nonesterified fatty acids (NEFA). Fully automated, computer-aided techniques were used for morphometric measurements of muscle biopsies from m. vastus lateralis. The hypertensive and normotensive groups did not differ in insulin sensitivity to glucose disposal (0.18+/-0.16 v. 0.19+/-0.13 micromol/kg/min/pmol/L; P = .20) and NEFA suppression (87.5+/-7.3 v. 87.2+/-9.4%, P>0.30) during a hyperglycemic clamp. The groups were similar in the proportion of types 1, 2a, and 2b muscle fibers, fiber size, and capillary density. Fiber roundness (ratio of fiber perimeter squared to fiber area) differed in the hypertensive (1.51+/-0.07) and normotensive (1.58+/-0.12, P = .004) groups, showing that the muscle fibers in the hypertensive group were more rounded in shape, a nonspecific change often seen after minimal ischemic lesions. The quotient expressing fiber roundness was associated with systolic (r = -0.29, P = .01) and diastolic (r = -0.32, P = .005) blood pressure. We conclude that persons with mild and moderate hypertension do not have abnormalities in muscle morphology that could explain the impairment of insulin action often observed in this condition. However, hypertensive individuals have increased muscle fiber roundness. It is wondered whether hypertension may be a condition with defects in the regulation of the transmembranous ion transport, leading to raised intracellular sodium concentration, swelling of the cytoplasma, and roundening of the fibers.

Adult↗

PubMed1999

Serum calcium and cardiovascular risk factors and diseases: the Tromsø study.

Total serum calcium levels were measured in 12 865 men and 14 293 women, between the ages of 25 and 97 years, in the Tromsø Study during 1994 and 1995. With the use of a sex-specific multiple linear regression model with age, calcium, body mass index, cholesterol, HDL cholesterol, triglycerides, systolic and diastolic blood pressure, and pulse as possible covariates, serum calcium was significantly (P<0.001) and positively associated with systolic and diastolic blood pressure, serum cholesterol, and HDL cholesterol in both sexes. A similar but weaker association was observed between serum calcium and triglycerides in men (P<0.01). In all age groups, serum calcium levels were higher in men with a history of myocardial infarction than in those without, and the difference was significant (P<0.0001) in a linear regression analysis adjusted for age. When all the other variables were also included in a logistic regression model, serum calcium was a highly significant (P<0.0001) predictor of myocardial infarction in men, with an odds ratio of 1.2 per 0.1 mmol/L increase in serum calcium. In women, a nonsignificant trend was again seen. Because the free or ionized form of calcium is the physiologically important form and serum calcium was not corrected for serum albumin in our study, the results must be interpreted with caution. However, it appears likely that serum calcium is a predictor of cardiovascular disease in men.

Adult↗

PubMed1999

Dietary and nutrient intake of a Sami population living in traditional reindeer herding areas in north Norway: comparisons with a group of Norwegians.

The Samis are an ethnic minority living in the Northern region of Norway, Sweden, Finland and Russia. Traditionally the Samis made their living from reindeer herding with some fishing and agriculture. Earlier studies have shown that their diet consisted of large amounts of reindeer meat, some fish and wild berries with low intakes of other fruits, vegetables and dairy products. Due to the introduction of technical improvements like snowmobiles and terrain vehicles which makes moving with the herd less necessary, their lifestyle has changed. There is little documentation how this has affected their dietary habits. In this study, the dietary pattern and nutrient intake of a group of Samis (n = 75) living in traditional reindeer herding areas of North Norway were investigated and compared with that of a group of Norwegians (n = 65). Dietary information was obtained through an interview by a nutritionist using the dietary history method. The findings indicate that nutrient content of the Sami diet is adequate except for folic acid. Calcium and iron intake was slightly below recommended levels for Sami females. There seems to be some difference between the diet of the Samis and Norwegians. The Samis consume more meat, fat, table sugar and coffee and less fruits and vegetables. The dietary pattern of the Samis seems, however, to be changing toward a more typically Norwegian diet.

Adult↗

PubMed1999

DNA polymorphisms of the apolipoprotein B gene (XbaI, EcoRI, and MspI RFLPs) in Norwegians at risk of atherosclerosis and healthy controls.

OBJECTIVES: Apo B is the exclusive protein constituent of LDL and is ligand on LDL, recognized and bound by the LDL receptor. Several restriction fragment length polymorphisms (RFLPs) of the apo B gene have been shown to be associated with variation in serum lipid levels in different populations. In this study we sought to determine the frequency of XbaI, EcoRI, and MspI polymorphisms and the haplotypes generated by these three polymorphic sites of the apo B gene and their influence on lipid levels in a sample of Norwegian subjects at risk of atherosclerosis and healthy control subjects. METHODS AND RESULTS: 108 White Norwegians at risk of atherosclerosis (cases) and 64 healthy individuals (controls) were examined for possible association between the alleles at the XbaI (X), EcoRI (R), and MspI (M) polymorphic restriction sites of the apolipoprotein B gene and serum lipid levels. The frequency of the M allele (absence of restriction site) was significantly higher in cases with high total cholesterol (TC), high low-density lipoprotein cholesterol (LDLC), and high apolipoprotein B (apo B) than in controls with normal TC, LDLC, and apo B (P < 0.04, P < 0.02, and P < 0.01, respectively). The frequencies of apo B genotypes detected with XbaI, EcoRI, and MspI did not differ significantly between cases and control subjects. A significant association between MspI genotypes and TC (P < 0.02), LDLC (P = 0.03), and apo B (P = 0.001) was observed only in cases. However, cases with the genotype M+/M+ had the lowest and those with the genotype M+/M- had the highest levels of serum TC, LDLC, and apo B. We did not observe any significant association between the alleles or genotypes detected with XbaI or EcoRI and serum lipid levels. In cases, genotypes defined by EcoRI and MspI RFLP paired loci differed significantly for apo B (chi 2 = 19; P = 0.007) but not for other blood lipids. EcoRI and MspI RFLPs change glutamic acid (Glu) 4154 to lysine (Lys) and arginine (Arg) 3611 to glutamine (Gln), respectively, which lie near the low density lipoprotein receptor binding region of apo B. Haplotypes containing "Lys/Arg Lys/Arg" (all basic amino acids) in cases were associated with low serum TC, LDLC, and apo B. In individuals at risk of atherosclerosis the concentration of serum lipids tends to be inversely related to the number of lysine and arginine. CONCLUSION: We conclude that variations in the apo B gene, resulting in changes of charged amino acids, affect the circulating blood lipids and that these may contribute to the risk of atherosclerosis.

Adult↗

PubMed1998

[Coronary heart diseases among Lapps and Norwegians in Finnmark].

The Finnmark Health Survey of 1987-88 showed that there was no significant difference in the prevalence of coronary heart disease between a Sámi population and a Norwegian population. Among men 40-59 years of age, a prevalence of myocardial infarction or angina pectoris or both, of 5.5%, was found both in Norwegians and in the predominantly Sámi population of Inner Finnmark. Among women, a prevalence of 3.1% and 3.3% was found among Norwegians and Sámis, respectively. The difference in results between males and females was less among Sámis than Norwegians, despite Sámi women having a lower risk factor level than Norwegian women. A clinical follow-up study done in 1992-93 showed no significant differences in serum lipid concentrations between the Sámi and the Norwegian population. Sámis had a lower familial occurrence of coronary heart disease than Norwegians. Waist to hip ratio was higher among Sámis than Norwegians.

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