Carotid artery intima-media thickness and brachial artery flow-mediated vasodilation in asymptomatic Japanese male subjects amongst apolipoprotein E phenotypes

Apolipoprotein E genotypes were not associated with intracranial atherosclerosis: a population-based autopsy study

BACKGROUND

Apolipoprotein E gene (APOE) ε4 allele is associated with a higher risk of carotid atherosclerosis, but less is known about the association of APOE with intracranial atherosclerotic disease (IAD). We aimed to investigate the association of APOE alleles with IAD in a cross-sectional autopsy study.

METHODS

We measured the stenosis in the 12 arteries of the Circle of Willis using postmortem morphometric measurements. The APOE polymorphism was determined by real-time polymerase chain reaction. We assessed the association between APOE polymorphism and IAD using regression models adjusted for sociodemographic and clinical variables. We also verified the modifier effect of age, sex, and race on this association. We stratified the analysis by age group to investigate the possibility of attrition bias.

RESULTS

In 400 participants (mean age=73.2±12.3 years old, 51% female, and 64% White), IAD was evaluated in 4,504 artery segments. APOE-ε4 was not associated with IAD nor with the number of artery stenosis compared to non-APOE-ε4 carriers. Sociodemographic variables did not modify this relationship. Among participants older than 70 years, there was a trend towards an association between APOE allele ε4 and a lower stenosis index in the middle cerebral artery, suggesting attrition bias related to the APOE-ε4 effect on mortality.

CONCLUSIONS

APOE alleles were not associated with IAD in this population-based autopsy study. Lower stenosis in older participants suggests the possibility of attrition bias.

Can and should carotid ultrasound be used in cardiovascular risk assessment?: the internist's perspective

Cardiovascular risk management is a major and challenging task for internists. Risk scores using algorithms based on traditional risk factors are helpful in identifying patients in whom intensive prevention strategies are warranted. However there remains a need for more accurate screening tools to allow clinicians to individualize the primary prevention programs to their patients. Approximately 40-80% of apparently healthy, asymptomatic subjects exhibit increased thickness of the lamina intima-media of the carotid artery or have atherosclerotic carotid plaques. These abnormalities can be measured safely and at low cost by ultrasound. Subclinical carotid lesions are strongly associated with generalized atherosclerotic burden and the risk of future cardiovascular events. Although many cardiovascular risk management guidelines recommend the use of these parameters incorporation in clinical practice is still not commonplace. Based on the current literature it can be stated that in high risk patients there is no additional value of carotid ultrasound because even in the absence of carotid lesions these patients should receive an intensive risk reduction regime. In the large low-intermediate risk group however carotid ultrasound findings carry subtle but possibly clinically relevant information about cardiovascular risk profile. The effect of treatment decisions based on carotid ultrasound parameters has not been studied. Sequential measurements to monitor progression and evaluate treatment response on an individual basis are not sufficiently reproducible. We therefore recommend the use of carotid ultrasound in low to intermediate risk patients but emphasize the importance of interpreting the results in conjunction with all cardiovascular risk factors and avoid follow-up measurements.

APOE polymorphism and carotid atherosclerosis in Korean population: the Dong-gu Study and the Namwon Study

OBJECTIVE

We evaluated the association between APOE polymorphism and carotid atherosclerosis in two large independent cohorts from South Korea.

METHODS

The datasets were from the Dong-gu Study (N = 9056) and the Namwon Study (N = 10,158). Carotid ultrasonography was performed to measure carotid intima-media thickness (IMT) and the presence of carotid plaques. The APOE polymorphism was determined by PCR-RFLP. We performed combined and separate analyses for the two datasets.

RESULTS

In the combined analysis, individuals with E2E2 or E2E3 genotype had a lower common carotid IMT compared with individuals with E3E3 genotype (0.684 mm vs. 0.736 mm, p = 0.007; 0.718 mm vs. 0.736 mm, p < 0.001, respectively). This association was very slightly attenuated but remained statistically significant after adjustment for blood lipids (0.690 mm vs. 0.736 mm, p = 0.033; 0.725 mm vs. 0.736 mm, p = 0.005, respectively). Compared with individuals with E3E3 genotype, individuals with E2E3 genotype had lower risk for carotid plaque (odds ratio (OR) = 0.83, 95% confidence interval (CI) = 0.75-0.93), while individuals with E3E4 genotype had a higher risk for carotid plaque (OR = 1.09, 95% CI = 1.00-1.20). After adjustment for blood lipids, ORs of E2E3 genotype for carotid plaque was slightly attenuated but remained significant (OR = 0.87 95% CI = 0.78-0.97), while OR of E3E4 genotype were slightly attenuated and not significant (OR = 1.08, 95% CI, 0.99-1.18).

CONCLUSIONS

We found that APOE polymorphism is associated with carotid atherosclerosis and this association was partly mediated through blood lipid. Our results suggest that APOE polymorphism may influence atherosclerosis through non-lipid pathways.

Flow-mediated vasodilation was found to be an independent predictor of changes in the carotid plaque status during a 5-year follow-up

AIM

It has previously been shown that flow-mediated vasodilation is a predictor of the progression of the intima-media thickness (IMT). In the present study, the degree of endothelium-dependent vasodilation in both resistance and conduit arteries was evaluated as a predictor of the IMT and plaque progression.

METHODS

In the population-based Prospective Study of the Vasculature in Uppsala Seniors(PIVUS) trial(1,016 subjects all 70 years of age), the invasive forearm technique using acetylcholine administered in the brachial artery (resistance artery, EDV) and the brachial artery ultrasound technique with measurement of flow-mediated dilatation (conduit artery, FMD) were evaluated. The IMT and number of carotid arteries with plaques (0, 1 or 2) were recorded using ultrasound at the baseline investigation and the follow-up visit conducted five years later.

RESULTS

A total of 760 subjects had valid measurements of the IMT and carotid artery plaques at both the investigations conducted at 70 and 75 years of age. Neither the FMD nor EDV significantly predicted the change in IMT over five years. However, the FMD, but not EDV, was associated with the change in carotid plaque burden during the follow-up period, independent of classical risk factors, such as gender, waist circumference, fasting blood glucose, systolic and diastolic blood pressure, HDL- and LDL-cholesterol, serum triglycerides, BMI and smoking (OR 0.81 for a 1 SD change in FMD, 95%CI 0.68 to 0.95, p=0.010).

CONCLUSIONS

The FMD was found to be a predictor of changes in the carotid plaque status, but not IMT, during the 5-year follow-up period, independent of classical cardiovascular risk factors.

The effects of apoA-I/C-III/A-IV, apoE and apoB polymorphisms on carotid artery intima-media thickness

Different apolipoprotein combinations explain most of the functional differences between plasma lipoproteins. This emphasizes the pivotal role of apolipoproteins in the homeostasis and physiological control of lipid metabolism. Genetic polymorphisms of apolipoprotein (apo)A-I/C-III/A-IV, apoE and apoB have been suggested to modulate plasma lipid levels as well as the risk of coronary artery disease and stroke. Carotid artery intima-media thickness has been shown to represent preclinical atherosclerosis and has, therefore, been used as a surrogate in quantifying the early stages of atherosclerosis. The effects of the polymorphisms in apoA-I/C-III/A-IV and apoB on carotid intima-media thickness are poorly known. The corresponding influence of apoE polymorphisms has been studied more extensively, but the results are not yet conclusive. In this review, these results are presented in detail and the potential reasons and mechanisms for the discrepancies are discussed.

Comparison of brachial and carotid artery ultrasound for assessing extent of subclinical atherosclerosis in HIV: a prospective cohort study

Background

Non-invasive surrogate measures which are valid and responsive to change are needed to study cardiovascular risks in HIV. We compared the construct validity of two noninvasive arterial measures: carotid intima medial thickness (IMT), which measures anatomic disease; and brachial flow-mediated vasodilation (FMD), a measure of endothelial dysfunction.

Methods

A sample of 257 subjects aged 35 years or older, attending clinics in five Canadian centres, were prospectively recruited into a study of cardiovascular risk among HIV subjects. The relationship between baseline IMT or FMD and traditional vascular risk factors was studied using regression analysis. We analyzed the relationship between progression of IMT or FMD and risk factors using fixed-effects models. We adjusted for use of statin medication and CD4 count in both models.

Results

Baseline IMT was significantly associated with age (p < 0.001), male gender (p = 0.034), current smoking status (p < 0.001), systolic blood pressure (p < 0.001) and total:HDL cholesterol ratio (p = 0.004), but not statin use (p = 0.904) and CD4 count (p = 0.929). IMT progression was significantly associated with age (p < 0.001), male gender (p = 0.0051) and current smoking status (p = 0.011), but not statin use (p = 0.289) and CD4 count (p = 0.927). FMD progression was significantly associated with current statin use (p = 0.019), but not CD4 count (p = 0.84). Neither extent nor progression of FMD was significantly associated with any of the examined vascular risk factors.

Conclusion

IMT correlates better than FMD with established cardiovascular risk factors in this cohort of HIV patients. Standardization of protocols for FMD and IMT will facilitate the comparison of results across studies.

Relationship between brachial flow-mediated dilation and carotid intima-media thickness in an elderly cohort: the Cardiovascular Health Study

OBJECTIVE

The aim of this study was to determine the relationship between brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) in a large multi-ethnic elderly cohort.

BACKGROUND

Brachial flow-mediated dilation (FMD) is a physiologic measure and carotid IMT is an anatomic structural measure of subclinical atherosclerosis. Both brachial FMD and carotid IMT have been associated with cardiovascular risk factors and cardiovascular events. The relationship between brachial FMD and carotid IMT is less clear especially in older adults.

METHODS

Brachial FMD, carotid IMT and traditional cardiovascular risk factors were measured in 2338 adults, age 72-98 years who were participants in the Cardiovascular Health Study. The relationship between FMD and IMT was assessed both unadjusted and also after adjusting for age, gender and race/ethnicity, BMI, HDL, LDL, systolic and diastolic blood pressure, serum creatinine, current smoking, diabetes mellitus, hormone therapy and prior CVD.

RESULTS

Both brachial FMD and carotid IMT correlated significantly with age, HDL levels, waist/hip ratio, serum cholesterol and number of CV risk factors. Brachial FMD was not associated with CCA IMT in this elderly cohort (Pearson partial correlation coefficient=-0.0252, p=0.222). In the adjusted linear regression model with CCA IMT as the dependent variable, brachial FMD was also not associated with CCA IMT (beta coefficient=-0.006, p=0.470).

CONCLUSION

Brachial FMD and CCA IMT are not related in population-based older adults. Brachial FMD and CCA IMT may be distinct and independent stages in the complex atherosclerotic process.

Relation of apolipoprotein E polymorphism to markers of early atherosclerotic changes in young adults--the Cardiovascular Risk in Young Finns Study

BACKGROUND

Carotid artery intima-media thickness (IMT), which is measured by ultrasound, is used in the assessment of early atherosclerotic changes, and has been associated with apolipoprotein E (APOE) polymorphism in many studies comprising elderly subjects. However, results are still inconclusive and data relating to young adults are missing. Whether common APOE polymorphism is related to carotid IMT was studied in a population of young adults. Also brachial flow-mediated dilatation (FMD) and carotid artery compliance (CAC) were determined to clarify their relation to this genetic factor.

METHODS AND RESULTS

A total of 1,188 young adults (aged 24-39 years) participating in the Cardiovascular Risk in Young Finns Study with complete data of common APOE polymorphism underwent a carotid and brachial ultrasound. Patients' lipid levels and blood pressure were also examined. There was no significant association between the APOE phenotypes and carotid IMT, brachial FMD or CAC either in young men or in young women. The results were similar for systolic and diastolic blood pressure. In the same population, the well-known association between APOE phenotypes and lipids was seen.

CONCLUSIONS

Common APOE polymorphism does not seem to be an independent genetic determinant of carotid IMT, brachial FMD or CAC.

Brachial artery vasoreactivity is associated with cross-sectional and longitudinal anatomical measures of atherosclerosis in postmenopausal women with coronary artery disease

BACKGROUND

The diagnostic and prognostic importance of brachial artery flow-mediated dilation (BFMD) for cardiovascular disease (CVD) is not certain and associations between BFMD and recognized measures of atherosclerosis have not been well established.

METHODS

We investigated cross-sectional and longitudinal correlations between repeated measures of BFMD and quantitative coronary artery angiographic (QCA) measurements of average percent diameter stenosis, number of lesions and minimum luminal diameter (MLD), and ultrasonographic measurement of carotid artery intima-media thickness (CIMT) in an ethnically diverse cohort of postmenopausal women (n=132) with coronary artery disease (CAD). Subjects were participants in a 3-year randomized, placebo-controlled clinical trial, testing the efficacy of hormone therapy on atherosclerosis progression. Associations between BFMD and QCA measures, and between BFMD and CIMT were examined using measurements from the same study visit.

RESULTS

BFMD was significantly inversely correlated with coronary artery stenosis at baseline (beta=-1.21% [S.E.(beta)=0.38], p=0.002). BFMD levels significantly predicted rate of change in CIMT over the trial period (beta=-0.76 microm/year [S.E.(beta)=0.29], p=0.008).

CONCLUSIONS

Physiological and anatomical measures of atherosclerosis are correlated among postmenopausal women with CAD, which provides some validation of BFMD as a measure of atherosclerosis in high-risk populations.

Association between apolipoprotein E genotype and carotid intima-media thickness may suggest a specific effect on large artery atherothrombotic stroke

BACKGROUND AND PURPOSE

Apolipoprotein E genotype (APOE) influences cholesterol levels and ischemic heart disease. Although there is no convincing overall association with ischemic stroke, APOE may influence large artery (atherothrombotic) stroke, for which carotid intima-media thickness (CIMT) is an informative intermediate phenotype. We therefore performed a systematic review and meta-analysis of the association between APOE and CIMT.

METHODS

We sought all published studies assessing the association between APOE and CIMT. From each study, we extracted available data on study methods, subjects' characteristics, and mean (and standard deviation) CIMT for each genotype or genotype group. We calculated study-specific and random effects pooled differences in mean CIMT between genotype groups, and assessed heterogeneity between studies and predefined subgroups using I(2) and chi(2) statistics.

RESULTS

Meta-analysis of 22 published studies (30,879 subjects) showed a significant association between APOE and CIMT (pooled mean difference epsilon 4- versus epsilon 2-allele containing genotypes 46 microm, 95% CI 29 to 62, P<0.00001). We found evidence of small study (mainly publication) bias, with a diminished (but still highly statistically significant) association in studies of >1000 subjects (pooled mean difference 17 microm, 95% CI 12 to 23, P<0.00001). The association was larger among high vascular risk and eastern Asian populations, but this may simply reflect the smaller size of these studies.

CONCLUSIONS

Our results show a clear association of APOE with CIMT, even though publication bias means that this is overestimated by the published literature. These findings suggest the possibility of a specific association with large artery ischemic stroke.

A common VLDLR polymorphism interacts with APOE genotype in the prediction of carotid artery disease risk

The genetic factors associated with carotid artery disease (CAAD) are not fully known. Because of its role in lipid metabolism, we hypothesized that common genetic variation in the very low density lipoprotein receptor (VLDLR) gene is associated with severe CAAD (>80% stenosis), body mass index (BMI), and lipid traits in humans. VLDLR was resequenced for variation discovery in 92 subjects, and single nucleotide polymorphisms (tagSNPs) were chosen for genotyping in a larger cohort (n = 1,027). Of the 17 tagSNPs genotyped, one tagSNP (SNP 1226; rs1454626) located in the 5' flanking region of VLDLR was associated with CAAD, BMI, and LDL-associated apolipoprotein B (apoB). We also identified receptor-ligand genetic interactions between VLDLR 1226 and APOE genotype for predicting CAAD case status. These findings may further our understanding of VLDLR function, its ligand APOE, and ultimately the pathogenesis of CAAD in the general population.

Apolipoprotein E epsilon4 genotype is independently associated with increased intima-media thickness in a recessive pattern

Polymorphisms in the apolipoprotein E (Apo E) gene have been associated with lipid levels, carotid intima media thickness (CCA-IMT), inflammation and cardiovascular disease (CVD). Earlier findings suggested an association of the Apo E alleles with increased CCA-IMT following a recessive pattern. Whether associations might be independent of C-reactive protein (CRP), lipid levels and other CVD risk factors is not known. We investigated the relationships between Apo E (epsilon2, epsilon3 and epsilon4 alleles) and CCA-IMT, measured by B-mode ultrasound, in dominant and recessive models in a community-based sample of 437 men 75 years of age. In men homozygous for the epsilon4 allele CCA-IMT was significantly increased by 0.13 mm to 0.86 +/- 0.16 mm compared to 0.73 +/- 0.19 mm in non- epsilon4-carriers (P = 0.0012) and 0.73 +/- 0.21 mm in epsilon4 heterozygous (P = 0.0044) in unadjusted recessive models. The association between Apo E epsilon4 genotype and CCA-IMT was independent of Apo E epsilon2 and Apo E epsilon3 alleles, CRP, lipid variables (TG, LDL, HDL) and other CVD risk factors (smoking, hypertension, body mass index, diabetes) (P = 0.018). No relations between Apo E genotype and CCA-IMT were observed in dominant models. No significant associations between the Apo E epsilon2 and epsilon3 alleles and CCA-IMT were found. In this study, men homozygous with the ApoE epsilon4 allele had thicker CCA-IMT, independently of Apo E epsilon2 and epsilon3 alleles, CRP, lipid variables (TG, LDL, HDL) and other CVD risk factors (smoking, hypertension, body mass index, diabetes), suggesting CCA-IMT to be modified by the ApoE epsilon4 genotype in a recessive pattern.

New Insight Into the Association of Apolipoprotein E Genetic Variants With Carotid Plaques and Intima-Media Thickness

BACKGROUND AND PURPOSE

Carotid plaques and elevated carotid artery intima-media thickness (IMT) are major predictors of vascular morbidity and mortality. Our aim was to test their association with 2 polymorphisms of the apolipoprotein E (apoE) gene, epsilon and -219G/T.

METHODS

The study was performed on 5856 subjects aged > or =65 years recruited from the French population for the Three-City Study. Carotid ultrasound examination included an assessment of atherosclerotic plaques in the extracranial carotid arteries and a measurement of IMT in the common carotid arteries (CCA) at a site free of plaques. The genetic association was tested using genotype and haplotype analyses.

RESULTS

In a multivariate analysis including both polymorphisms and vascular risk factors, carotid plaques were more frequent in epsilon4 homozygotes (adjusted odds ratio=2.12, 95% CI=1.27 to 3.53) and less frequent in epsilon2 carriers (adjusted odds ratio=0.79, 95% CI=0.66 to 0.95) compared with epsilon3 homozygotes. Adjusting for and stratifying on lipid levels did not modify these results. CCA-IMT was higher in carriers of the epsilon34 genotype (mean CCA-IMT=0.744 mm versus 0.732 mm for the epsilon33 genotype, P=0.002), but the association disappeared after excluding subjects with carotid plaques. No association was found between the -219 polymorphism and either carotid plaques or CCA-IMT, and there was no interaction or cis-effect between -219 and epsilon.

CONCLUSIONS

This study, conducted on a large population cohort of French elderly, demonstrated that carotid plaques were significantly associated with the apoE epsilon polymorphism independently of the -219 polymorphism and vascular risk factors, in particular lipid levels.

Relations of APOE promoter polymorphisms to LDL cholesterol and markers of subclinical atherosclerosis in young adults

The common apolipoprotein E (apoE) gene (APOE) epsilon2/epsilon3/epsilon4 polymorphism explains part of serum lipid variation, and polymorphisms in the APOE promoter region have been proposed to participate in the regulation of serum lipid levels within the most common APOE epsilon3/epsilon3 genotype group. We determined APOE -219G/T and +113G/C promoter genotypes and estimated APOE haplotypes in 525 participants of the Cardiovascular Risk in Young Finns Study. We studied the associations of the APOE promoter polymorphisms and their haplotypes with cross-sectional and longitudinal serum lipid and apolipoprotein concentrations as well as with flow-mediated dilatation (FMD), carotid artery compliance (CAC), and intima-media thickness (IMT) within the APOE epsilon3/epsilon3 carriers. We found no significant association between the APOE promoter genotypes and serum lipids [low density lipoprotein-cholesterol (LDL-C), HDL-C, and triglycerides], apolipoproteins (apoA-I and apoB), or brachial artery FMD, CAC, or carotid IMT in either men or women. In longitudinal analyses in males, the carriers of heterozygous genotypes (-219G/T or +113G/C) and, furthermore, carriers of the -219T/+113C/epsilon3 haplotype had significantly higher LDL-C and total cholesterol concentrations throughout the 21 year follow-up period compared with homozygous G allele carriers or noncarriers of the -219T/+113C/epsilon3 haplotype. Such associations were not found in females. In summary, the APOE promoter polymorphisms -219G/T and +113G/C as well as their haplotype are associated with longitudinal changes in LDL-C and total cholesterol concentrations in young Finnish males but do not seem to be major determinants for FMD, CAC, or carotid IMT in males or females.

Relationship Between Carotid Artery Intima-Media Thickness and Brachial Artery Flow-Mediated Dilation in Middle-Aged Healthy Men

OBJECTIVES

We aimed to determine the relationship between carotid intima-media thickness (IMT) and brachial artery flow-mediated dilation (FMD) in healthy middle-age men.

BACKGROUND

Carotid IMT and brachial artery FMD are frequently used as surrogate measures of subclinical atherosclerosis. Whereas carotid IMT identifies early structural abnormalities, brachial artery FMD, considered a bioassay of endothelial function, measures functional vascular integrity. The relationship between carotid IMT and brachial artery FMD has not been well studied.

METHODS

We measured traditional risk factors, carotid IMT, and brachial artery FMD in 1,578 middle-aged men without known cardiovascular disease and analyzed the relationship between carotid IMT and brachial FMD.

RESULTS

Carotid IMT correlated with age, systolic blood pressure, body mass index, fasting glucose, total and low-density lipoprotein (LDL) cholesterol, and with the overall Framingham risk score (p < 0.001 for all), whereas impaired brachial artery FMD correlated with systolic and diastolic blood pressure (p < 0.01). No relationship was observed between carotid IMT and brachial artery FMD for the entire cohort (r = -0.006, p = 0.82) and in subgroups defined by traditional risk factors or by quintiles of carotid IMT and brachial FMD.

CONCLUSIONS

In middle-aged healthy men, there is no significant correlation between carotid IMT and brachial artery FMD. This finding suggests that these are unique, independent surrogates that measure different aspects and stages of early atherosclerosis. Further studies are needed to define their role in clinical research and in cardiovascular risk assessment.

POLYMORPHISMS OF APOLIPOPROTEIN E AND ANGIOTENSIN-CONVERTING ENZYME GENES AND CAROTID ATHEROSCLEROSIS IN HEAVY DRINKERS

AIMS

To investigate the influence of apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) gene polymorphisms on carotid artery atherosclerosis in alcoholism.

METHODS

Polymorphism of both genes was identified by DNA analysis in 130 male alcohol-dependent patients. Intima-media thickness (IMT) was measured ultrasonographically.

RESULTS

Multivariate regression analysis showed that of all the known risk factors the greatest impact on carotid atherosclerosis in alcoholics was exerted by age, hypertension, LDL cholesterol and fasting plasma glucose levels. Subjects carrying the APO E epsilon4 allele were more liable to develop atherosclerotic changes in carotid arteries compared with subjects with the epsilon3/3 genotype, which showed statistical significance in patients under 50 years of age. No association was shown between ACE I/D polymorphism and carotid atherosclerosis.

CONCLUSIONS

APO E polymorphism can increase the risk of carotid atherosclerosis development in an alcoholic subject. The association of the APO E epsilon4 allele with carotid atherosclerosis was significant in younger patients. Since the elevated carotid IMT is considered to be a good marker of increased risk of generalized atherosclerosis the consequences could involve both cardiac and cerebrovascular events.

Apolipoprotein E phenotype affects the malondialdehyde-modified LDL concentration and forearm endothelial function in postmenopausal women

OBJECTIVE

We investigated whether the apolipoprotein E (apo E) phenotype affects the serum concentration of malondialdehyde-modified low-density lipoprotein (MDA-LDL) or forearm endothelial function in postmenopausal women.

PATIENTS AND MEASUREMENTS

Individuals were divided into three groups according to their apo E phenotype: E2 (E2/2 and E2/3, n = 12); E3 (E3/3, n = 71); and E4 (E3/4 and E4/4, n = 27). The serum concentrations of lipids and MDA-LDL were measured. Forearm blood flow during reactive hyperaemia and after sublingual nitroglycerin administration was measured by strain-gauge plethysmography.

RESULTS

The serum concentrations of total and LDL cholesterol were significantly higher in the E4 group than in the E2 group (P < 0.05) or in the E3 group (P < 0.05). The serum apo B concentration was significantly higher in the E4 group than in the E2 group (P < 0.05). The serum concentrations of high density lipoprotein (HDL) cholesterol and nitrite/nitrate were significantly lower in the E4 group than in the E2 group (P < 0.05). Other lipid concentrations did not differ in the three groups. The serum MDA-LDL concentration was highest in the E4 group, and was lowest in the E2 group (E2: 91.1 +/- 6.9 IU/l, E3: 112.3 +/- 5.9 IU/l, E4: 128.8 +/- 9.9 IU/l; P < 0.05). The forearm blood flow response to reactive hyperaemia was lowest in the E4 group, and highest in the E2 group (E2: 52.2 +/- 5.8 ml/min per 100 ml tissue, E3: 40.7 +/- 1.7 ml/min per 100 ml tissue, E4: 33.4 +/- 2.4 ml/min per 100 ml tissue; P < 0.05). The forearm blood flow changes in response to nitroglycerine were similar between all three groups.

CONCLUSIONS

The apo E phenotype affects the serum MDA-LDL concentration and forearm endothelial function in postmenopausal women.

New advances in identifying genetic anomalies in stroke-prone probands

The past several years have been marked by significant progress in identifying genetic anomalies in stroke-prone probands. These advances have occurred in both highly penetrant single-gene disorders and in common stroke, which is influenced by risk/susceptibility genes. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) can be challenging to diagnose because of the wide range of notch 3 mutations that can cause disease, but a new immunohistochemical technique using a skin biopsy sample appears to be highly sensitive and specific. In a landmark Icelandic study, linkage was established between stroke and a locus on chromosome 5q12 designated STRK1. Association studies continue to identify polymorphisms that predispose to stroke and to markers for cerebrovascular atherosclerosis, such as intima-media thickness. Intense interest now surrounds genes involved in inflammation, including genes that encode for the interleukin-1 receptor antagonist and paraoxonase-1. In the foreseeable future, prevention, diagnosis, and treatment will incorporate genetic data to refine and individualize management of cerebrovascular disease.

Association of APOE genotype with carotid atherosclerosis in men and women

The aim of this study was to determine the association between APOE genotype and carotid atherosclerosis, defined as intimal-medial thickness (IMT) and stenosis, and to assess if other cardiovascular risk factors modify this association. A total of 1,315 men and 1,408 women from the Framingham Offspring Study underwent carotid ultrasound during examination cycle 6 and had complete data on APOE genotype. Three APOE genotype groups were defined: APOE2 (including E2/E2, E3/E2 genotypes), APOE3 (E3/E3), and APOE4 (including E4/E3, E4/E4 genotypes). Carotid IMT and the presence of carotid stenosis > 25% were determined by ultrasonography. In women, the APOE2 group was associated with lower carotid IMT (0.67 vs. 0.73 mm) and lower prevalence of stenosis (odds ratio = 0.49; 95% confidence interval = 0.30-0.81) compared with the APOE3 group. In men, APOE genotype was not associated with carotid IMT or stenosis in the whole group; however, diabetes modified the association between APOE genotype and carotid IMT (P for interaction = 0.044). Among men with diabetes, the APOE4 group was associated with a higher internal carotid artery IMT (1.22 mm) than the APOE3 group (0.90 mm) or the APOE2 group (0.84 mm). The E2 allele was associated with lower carotid atherosclerosis in women, and the E4 allele was associated with higher internal carotid IMT in diabetic men.

Genetics of Ultrasonographic Carotid Atherosclerosis

The search for genes related to the cause of common complex disorders such as cardiovascular disease has been frustrating, partly because of the many factors known to contribute to cardiovascular disease and the potential "distance" of cardiovascular disease as a phenotype from genes and gene products. Linkage and association studies for phenotypes more proximal in the pathway from DNA sequence variation to overt clinical disease, such as ultrasound-defined carotid atherosclerosis, may potentially be more enlightening. Only one genetic variant previously reported to be associated with atherosclerosis or clinically evident cardiovascular disease, matrix metalloproteinase (MMP) 3, has shown consistently positive associations with carotid disease, although it has not been studied widely. Another, PON1 L55M, is weakly associated in subgroups only, and 2, ApoE and MTHFR, are equivocal. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis. This may reflect the known inconsistency in associations of genetic variants with clinical cardiovascular disease itself. Alternatively, genetic determinants of ultrasound-defined carotid atherosclerosis may differ from those of clinically manifest cardiovascular disease and may require pursuit through large-scale genomic studies of carotid atherosclerosis as a distinct phenotype. Only 1 genetic variant, MMP 3, has shown consistently positive associations with ultrasonographic carotid disease, although it has not been studied widely. Another, PON1 L55 mol/L, is weakly associated in subgroups only. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis.

The role of cardiovascular risk factors in Alzheimer's disease

The distinction between Alzheimer's disease and vascular dementia, the two most common types of dementia, has been undermined by recent advances in epidemiologic, clinical, imaging, and neuropathological studies. Cardiovascular risk factors, traditionally regarded as distinguishing criteria between the two entities, have been shown to be associated with both AD and vascular dementia. In this article, we propose mechanisms of action of cardiovascular risk factors in AD, suggest possible explanations for the overlap with vascular dementia and discuss the implications this might have on future differential diagnosis, research, and treatment strategies.

New advances in identifying genetic anomalies in stroke-prone probands

The past several years have been marked by significant progress in identifying genetic anomalies in stroke-prone probands. These advances have occurred in both highly penetrant single-gene disorders and in common stroke, which is influenced by risk/susceptibility genes. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) can be challenging to diagnose because of the wide range of notch 3 mutations that can cause disease, but a new immunohistochemical technique using a skin biopsy sample appears to be highly sensitive and specific. In a landmark Icelandic study, linkage was established between stroke and a locus on chromosome 5q12 designated STRK1. Association studies continue to identify polymorphisms that predispose to stroke and to markers for cerebrovascular atherosclerosis, such as intima-media thickness. Intense interest now surrounds genes involved in inflammation, including genes that encode for the interleukin-1 receptor antagonist and paraoxonase-1. In the foreseeable future, prevention, diagnosis, and treatment will incorporate genetic data to refine and individualize management of cerebrovascular disease.

Is the distinction between Alzheimer's disease and vascular dementia possible and relevant?

Advances in epidemiological, clinical, imaging, and neuropathological studies have undermined the clear distinction between vascular and Alzheimer-type dementia, which has characterized the last two decades of research in dementia. A significant degree of overlap between the two entities was demonstrated in terms of clinical expression, risk factors, and postmortem brain autopsy. In this article, we propose mechanisms by which cardiovascular risk factors might affect the manifestation of Alzheimer's disease, suggest possible explanations for the overlap with vascular dementia, and discuss the implications this might have on future differential diagnosis and treatment strategies.

Genetics of intima-media thickness

PURPOSE OF REVIEW

Increased carotid artery intima-media thickness is associated with an increased risk of coronary heart disease or cerebrovascular disease and is a powerful predictor of cardiovascular and cerebrovascular outcomes. Consequently, the measurement is now used in a number of case control, cohort and familial and linkage studies as an intermediate phenotype for the investigation of the genetic and environmental determinants of atherosclerosis. The aim of this paper is to review the most recent available data on the genetic determinants of carotid intima-media thickness.

RECENT FINDINGS

Genes could account for a significant amount of variation in carotid intima-media thickness: up to 30-66%. Carotid intima-media thickness progressed more rapidly with age in familial hypercholesterolemia patients than in patients without his condition. Familial hypercholesterolemia patients with a null LDL receptor allele tended to have higher carotid intima-media thickness than patients carrying the LDL receptor defective allele. Small association studies showing positive or negative results with the angiotensinogen gene variants as well as with the angiotensin converting enzyme I/D polymorphism add to the confusion in this largely controversial area. Differing results may depend on the vascular territory and genetic background. New associations have been described in small studies.

SUMMARY

Studies on the association of polymorphisms and intima-media thickness are frequently disappointing and lead occasionally to conflicting results. Among study limitations is the fact that mostly single gene effects are considered; longitudinal cohort studies may be more appropriate than case control studies. Ongoing large prospective population studies and clinical trials have integrated the measurements of intima-media thickness and genotype determination with a genomic approach. As a result, in the near future we may see more important and robust results with significant consequences on our understanding of genetic determinants of atherosclerotic cardiovascular disease.

Apolipoprotein and apolipoprotein receptor genes, blood lipids and disease

PURPOSE OF REVIEW

Apolipoproteins and their receptors are the main controllers of lipid metabolism and, as such, have a major impact not only on the risk of cardiovascular disease but also on the development and degeneration of the central nervous system. Variations in the genes coding for these apolipoproteins and their receptors and the interaction with the environment determine individual susceptibility to metabolic disturbances, the response to dietary or pharmacological intervention and, finally, to disease.

RECENT FINDINGS

This review will focus on recent findings, such as the latest concepts regarding apolipoprotein E in neurodevelopment, the newly identified apolipoprotein A-V and its influence in triglyceride metabolism, and the improved understanding of apolipoprotein A-I and HDL metabolism in the light of the discovery of the ABC family of transporters. Other key aspects of lipoprotein metabolism and cardiovascular disease risk such as apolipoprotein B-100, the LDL receptor, apolipoprotein C-III or apolipoprotein (a) will be updated.

SUMMARY

Variations in these genes will be analysed in relation to plasma lipid levels, their interactions with diet, treatment or other environmental stimuli, and their influence on the risk of cardiovascular disease and neurological disorders.