Associations of plasma homocysteine and the methylenetetrahydrofolate reductase C677T polymorphism with carotid intima media thickness among South Asian, Chinese and European Canadians

Homocysteine, Vitamins B6, B12, and Folate and the Risk of Ischemic and Hemorrhagic Stroke: A Case-control Study from Northeast India

Background

Stroke is a major leading global health complication. Identification and management of risk factors associated with stroke can help in prior detection, prevention, and improvement in patient care.

Purpose

To investigate the prevalence of hyperhomocysteinemia (HHcy) and Vitamins B6, B12, and folate deficiency in stroke patients and also to assess other risk factors associated with ischemic and hemorrhagic stroke.

Methods

Detail history of all the subjects in the study including history of hypertension, anemia, fasting glucose, carotid artery thickness, smoking, alcohol, and dietary intake was recorded. Standard assays for homocysteine (Hcy), Vitamins B6, B12, and folate estimation were done. Lipid and renal profile tests were also performed. The prevalence and odds of having HHcy, Vitamins B6, B12, and folate deficiency, and other risk factors in ischemic and hemorrhagic stroke patients were evaluated. Student’s t-tests and chi-square tests were done for statistical validation of the data.

Results

Prevalence of HHcy and Vitamins B6, B12, and folate deficiency was not observed in ischemic cases. HHcy and folate deficiency was found to be prevalent in hemorrhagic stroke patients. The odds that a person with HHcy and folate deficiency has hemorrhagic stroke was found to be significantly high.

Conclusion

In our study, high Hcy and low folate levels emerged as risk factors for hemorrhagic stroke.

Association of the methylenetetrahydrofolate reductase (MTHFR) gene variant C677T with serum homocysteine levels and the severity of ischaemic stroke: a case-control study in the southwest of China

OBJECTIVE

To determine whether the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism is linked to the risk of ischaemic stroke and circulating homocysteine (Hcy) levels in a Chinese population.

METHODS

This case-control study recruited angiogram-diagnosed patients with ischaemic stroke and healthy control subjects. The plasma Hcy concentrations were measured and the MTHFR C677T gene polymorphism was genotyped. The National Institutes of Health Stroke Scale (NIHSS) was used to assess the severity of the ischaemic stroke.

RESULTS

This study recruited 198 patients with ischaemic stroke and 168 controls. The TT genotype conferred a higher risk for ischaemic stroke than the CC genotype (odds ratio of 3.563; 95% confidence interval [CI] 1.412, 4.350). The T allele was the predisposing allele for ischaemic stroke. Hcy had an area under the receiver operating characteristic (ROC) curve of 0.624 (95% CI 0.530, 0.758). The ROC for Hcy demonstrated its usefulness in predicting ischaemic stroke. Hcy levels were not associated with ischaemic stroke severity as measured by the NIHSS.

CONCLUSION

The MTHFR C677T gene polymorphism affects circulating Hcy levels. The MTHFR C677T gene polymorphism and hyperhomocysteinaemia may play important roles in predicting the risk of ischaemic stroke.

Vitamin B12, folate and homocysteine concentrations during pregnancy and early signs of atherosclerosis at school-age

Background & aims

Suboptimal circulating vitamin B12, folate and homocysteine concentrations during fetal life seem to be associated with cardiometabolic health at school-age. We examined whether fetal exposure to lower circulating vitamin B12 and folate concentrations and higher circulating homocysteine concentrations is also associated with early signs of atherosclerosis at school-age.

Methods

This study among 3826 school-age children and their mothers was embedded in the Generation R Study, a population-based prospective cohort study from early pregnancy onwards. We examined the associations of early-pregnancy and cord blood serum total and active B12 and plasma folate and homocysteine concentrations with common carotid artery intima-media thickness and distensibility in the children aged ten years.

Results

As compared to normal early-pregnancy serum total B12 concentrations (≥145 pmol/L), low serum total B12 concentrations (<145 pmol/L) were associated with higher carotid intima-media thickness in the children at school-age (difference 0.09 standard deviations score (SDS); 95% confidence interval (CI): 0.01, 0.16). As compared to normal early-pregnancy plasma folate concentrations (≥8 nmol/L), low plasma folate concentrations (<8 nmol/L) were associated with lower carotid disten-sibility in the children at school-age (difference −0.16 SDS; 95% CI: −0.28, −0.04). Early-pregnancy circulating total and active B12, folate and homocysteine concentrations measured continuously were not associated with carotid intima-media thickness or carotid distensibility in the children at school-age. One SDS higher plasma homocysteine concentrations measured in cord blood at birth was associated with a −0.05 SDS (95% CI: −0.09, −0.02) lower carotid distensibility at school-age. Cord blood total and active B12 and folate concentrations were not associated with carotid intima-media thickness or carotid distensibility at school-age.

Conclusions

Circulating total B12, folate and homocysteine concentrations during fetal life seem to be associated with markers of subclinical atherosclerosis at school-age. Further studies need to examine the causality and mechanisms underlying these associations.

Serum Homocysteine, Folate, and Vitamin B12 Levels in Patients with Systemic Lupus Erythematosus: A Meta-Analysis and Meta-Regression

BACKGROUND

Patients with systemic lupus erythematosus (SLE) have elevated cardiovascular risk. Hyperhomocysteinemia may be one of the contributing factors to this phenomenon. This study therefore aimed to compare the serum homocysteine levels and the levels of folate and vitamin B12, cofactors for homocysteine metabolism, between individuals with and without SLE.

METHODS

A literature search was performed in PubMed, Embase, and the Cochrane library (from inception to March 31, 2019). Studies comparing serum homocysteine, folate or vitamin B₁₂ levels between individuals with and without SLE were selected. Of the 1040 screened studies, 50 studies met the inclusion criteria.

RESULTS

A total of 50 studies involving 4396 patients with SLE were included. Patients with SLE had a significantly higher serum level of homocysteine (standardized mean difference [SMD], 1.134; 95% CI, 0.795-1.474) and lower level of vitamin B₁₂ (SMD, -0.359; 95% CI, -0.638 to -0.080) than controls. The folate level didn't differ markedly between SLE patients and the control group (SMD, -0.276; 95% CI, -0.674-0.123). Subgroup analysis showed consistent results in adult SLE patients. A random effects meta-regression analysis revealed a significantly inverse correlation between the SMD of homocysteine levels and C3 levels (coefficient, -0.0356, 95% CI, -0.054 to -0.0171; P < .001) and C4 levels (coefficient, -0.0876, 95% CI, -0.1407 to -0.0345; P = .0012).

CONCLUSIONS

Serum homocysteine levels were higher and vitamin B₁₂ levels were lower among individuals with SLE than those without SLE. Physicians are encouraged to monitor these parameters and offer timely interventions for patients with SLE.

Expression of the C677T Polymorphism of the 5, 10-Methylenetetrahydrofolate Reductase (MTHFR) Gene in Patients with Carotid Artery Atherosclerosis

Background

The C677T polymorphism of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism has been associated with hypertension and coronary heart disease, but its relationship with carotid artery remains unknown. This study aimed to investigate the association between the C677T polymorphism of the MTHFR gene in patients with confirmed carotid artery atherosclerosis.

Material/Methods

This retrospective study included 210 patients with carotid artery atherosclerosis (the patient group) and 210 controls (the control group). Color Doppler ultrasound was used to identify carotid artery intimo-medial thickness and atherosclerotic plaques. Sanger sequencing using the polymerase chain reaction (PCR) was used to detect the MTHFR C677T gene polymorphism. Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose (FPG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), glycosylated hemoglobin (HbA1c), and other laboratory indicators were measured.

Results

SBP, DBP, FPG, TC, LDL-C, HbA1c, and intimo-medial thickness were significantly increased in the patient group compared with the control group, and HDL-C was significantly lower. The allele frequencies of the C667T locus of MTHFR gene were significantly different between the two groups (P<0.05), and the TT genotype and the T allele frequencies in the patient group were higher than in the control group. Logistic regression analysis showed that SBP, TC, LDL-C, and the C667T MTHFR gene polymorphism were risk factors for carotid artery atherosclerosis.

Conclusions

The C677T polymorphism of the MTHFR gene was expressed in patients with carotid artery atherosclerosis.

Homocysteine, but not MTHFR gene polymorphism, influences depressive symptoms in patients with schizophrenia

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is the key enzyme of folate metabolism in the process of one-carbon cycle and its deficiency results in elevated homocysteine concentration. In this study, we hypothesized that MTHFR C677T polymorphism and homocysteine concentration may play important roles in the development of depressive symptoms in schizophrenia.

METHODS

We recruited 715 patients with stable schizophrenia, and among them, 197 schizophrenia patients under olanzapine monotherapy were enrolled for homocysteine concentration analysis. The Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS) were employed to evaluate psychiatric and depressive symptoms.

RESULTS

When the 715 schizophrenia patients were evaluated by CDSS, 326 individuals (45.6%) had depressive symptoms. No significant differences were observed in C677T genotype and allele distributions between the schizophrenia with or without depression groups. Schizophrenia patients with depression have higher levels of homocysteine than those without depression (P = 0.019). There was a positive correlation between the homocysteine levels and CDSS score (r = 0.22, P = 0.002).

CONCLUSION

Our findings suggested that higher levels of homocysteine may be a risk factor for the development of depressive symptoms in schizophrenia patients.

Serum Homocysteine Levels Had Important Associations with Activity and Quality of Daily Living in Chinese Centenarians

BACKGROUND

Population aging is an important problem worldwide, with activity and quality of daily living commonly reduced in elderly people. leading to increased hospitalization and mortality rates, and substantial individual and social burdens.

OBJECTIVE

This study was designed to investigate the associations of serum homocysteine levels with activity and quality of daily living in Chinese centenarians for the first time.

PARTICIPANTS

The China Hainan Centenarian Cohort Study was performed in 18 cities and counties of Hainan Province.

MAIN MEASURES

Home interview, physical examination and blood analysis were performed in 787 centenarians following standard procedures.

KEY RESULTS

The median age was 102 years, ranging between 100 and 115 years. There were 634 females (80.6%) and 153 males (19.4%) in all. The median level of serum homocysteine was 23.80 (18.80-29.90) umol/L, whereas median values of Barthel Index and EuroQol 5 Dimensions were 85(60-95) and 0.661(0.558-0.766), respectively. The centenarians with serum homocysteine levels ≥23.8μmol/L were more likely to had lower values of Barthel Index and EuroQol 5 Dimensions than those with serum homocysteine levels <23.8μmol/L (P<0.05 for all). In multivariate linear regression analyses, serum homocysteine levels were significantly associated with Barthel Index and EuroQol 5 Dimensions (P<0.05 for all).

CONCLUSIONS

Serum homocysteine levels had important associations with activity and quality of daily living in Chinese centenarians. Future research should focus on the value of intervening in serum homocysteine levels by supplying folic acid (vitamin B9) and vitamin B12 on improving activity and quality of daily living in elderly people.

Contribution of MTHFR gene variants in lupus related subclinical atherosclerosis

OBJECTIVE

Elevated concentrations of homocysteine have been previously identified as an independent risk factor for subclinical atherosclerosis in patients with systemic lupus erythematosus (SLE). Given that heightened homocysteine levels are known to be strongly influenced by genetic factors, in the current study we investigated the contribution of high homocysteine levels as well as of functional polymorphisms of the gene encoding for the enzyme 5, 10- methylenetetrahydrofolate reductase (MTHFR) to atherosclerotic disease characterizing SLE patients.

METHODS

Peripheral DNA samples from 150 SLE patients, 214 rheumatoid arthritis (RA) patients and 561 age/sex matched apparently healthy volunteers (HC) were genotyped by PCR-based assays for the detection of the MTHFR gene polymorphisms (c. 677C > T and c. 1298A > C). All SLE patients and 30 age sex matched RA patients underwent assessment for subclinical atherosclerosis [ultrasound measurement of intima-media thickness scores (IMT) and detection of carotid and/or femoral (C/F) plaque] and complete clinical and laboratory evaluation including serum homocysteine levels. Data were analyzed using univariate and multivariate models (SPSS 21.0).

RESULTS

Hyperhomocysteinemia was detected in 26.0% of SLE patients compared to 6.7% of age/sex matched RA controls (p = 0.02). Higher serum B12 levels and decreased frequency of the MTHFR 677TT variant in RA patients could potentially account for the observed differences between the groups. In SLE patients, both hyperhomocysteinemia and MTHFR 677TT genotype were identified as independent contributors for plaque formation, following adjustment for traditional cardiovascular risk factors and disease related features, including age, sex, BMI, cholesterol and triglyceride levels, presence of arterial hypertension, smoking (pack/years), disease duration and total steroid dose [OR 95% (CI): 5.8 (1.0-35.8) and 5.2 (1.1-24.0), respectively]. MTHFR 677TT genotype, but not hyperhomocysteinemia was also found to confer increased risk for arterial wall thickening, after the above confounders were taken into account [OR (95%) CI: 4.9 (1.2-20.6)].

CONCLUSIONS

Hyperhomocysteinemia and MTHFR 677TT genetic variant emerged as independent risk factors for subclinical atherosclerosis in SLE patients, implying genetic influences as potential contributors to the increased burden of atherosclerotic disease characterizing SLE.

Cardiovascular disease in systemic lupus erythematosus: A comprehensive update

Heightened rates of both cardiovascular (CV) events and subclinical atherosclerosis, documented by imaging and vascular function techniques are well established in systemic lupus erythematosus (SLE). While traditional CV factors such as smoking, dyslipidemia, diabetes mellitus (DM), hypertension, central obesity and hyperhomocysteinemia have been reported to be prevalent in lupus patients, they do not fully explain the high rates of ischemic events so far reported, implying that other factors inherent to disease itself could account for the enhanced risk, including disease duration, activity and chronicity, psychosocial factors, medications, genetic variants and altered immunological mechanisms. Though the exact pathogenesis of atherosclerosis in the setting of lupus remains ill defined, an imbalance between endothelial damage and atheroprotection seems to be a central event. Insults leading to endothelial damage in the setting of lupus include oxidized low density lipoprotein (oxLDL), autoantibodies against endothelial cells and phospholipids, type I interferons (IFN) and neutrophil extracellular traps (NETs) directly or through activation of type I IFN pathway. Increased oxidative stress, reduced levels of the normally antioxidant high density lipoprotein (HDL), increased levels of proinflammatory HDL (piHDL) and reduced paraoxonase activity have been related to increased oxLDL levels. On the other hand, impaired atheroprotective mechanisms in lupus include decreased capacity of endothelial repair-partly mediated by type I IFN- and dampened production of atheroprotective autoantibodies. In the present review, traditional and disease related risk factors for CV disease (CVD) in the setting of chronic autoimmune disorders with special focus on SLE will be discussed.

An Examination of Stroke Risk and Burden in South Asians

BACKGROUND

South Asians (India, Pakistan, Sri Lanka, Bangladesh, Nepal, and Bhutan) are at a disproportionately higher risk of stroke and heart disease due to their cardiometabolic profile. Despite evidence for a strong association between diabetes and stroke, and growing stroke risk in this ethnic minority-notwithstanding reports of higher stroke mortality irrespective of country of residence-the explanation for the excess risk of stroke remains unknown.

METHODS

We have used extensive literature review, epidemiologic studies, morbidity and mortality records, and expert opinions to examine the burden of stroke among South Asians, and the risk factors identified thus far.

RESULTS

We summarize existing evidence and indicate gaps in current knowledge of stroke epidemiology among South Asian natives and immigrants.

CONCLUSIONS

This research focuses attention on a looming epidemic of stroke mainly due to modifiable risk factors, but also new determinants that might aggravate the effect of vascular risk factors in South Asians causing more disabling strokes and death.

Associations between homocysteine metabolism related SNPs and carotid intima-media thickness: a Chinese sib pair study

Carotid intima-media thickness (CIMT) is a good surrogate for atherosclerosis. Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. We aim to investigate the relationships between homocysteine (Hcy) related biochemical indexes and CIMT, the associations between Hcy related SNPs and CIMT, as well as the potential gene–gene interactions. The present study recruited full siblings (186 eligible families with 424 individuals) with no history of cardiovascular events from a rural area of Beijing. We examined CIMT, intima-media thickness for common carotid artery (CCA-IMT) and carotid bifurcation, tested plasma levels for Hcy, vitamin B6 (VB6), vitamin B12 (VB12) and folic acid (FA), and genotyped 9 SNPs on MTHFR, MTR, MTRR, BHMT, SHMT1, CBS genes. Associations between SNPs and biochemical indexes and CIMT indexes were analyzed using family-based association test analysis. We used multi-level mixed-effects regression model to verify SNP-CIMT associations and to explore the potential gene–gene interactions. VB6, VB12 and FA were negatively correlated with CIMT indexes (p < 0.05). rs2851391 T allele was associated with decreased plasma VB12 levels (p = 0.036). In FABT, CBS rs2851391 was significantly associated with CCA-IMT (p = 0.021) and CIMT (p = 0.019). In multi-level mixed-effects regression model, CBS rs2851391 was positively significantly associated with CCA-IMT (Coef = 0.032, se = 0.009, raw p < 0.001) after Bonferoni correction (corrected α = 0.0056). Gene–gene interactions were found between CBS rs2851391 and BHMT rs10037045 for CCA-IMT (p = 0.011), as well as between CBS rs2851391 and MTR rs1805087 for CCA-IMT (p = 0.007) and CIMT (p = 0.022). Significant associations are found between Hcy metabolism related genetic polymorphisms, biochemical indexes and CIMT indexes. There are complex interactions between genetic polymorphisms for CCA-IMT and CIMT.

The Impact of Homocysteine, Vitamin B12, and Vitamin D Levels on Functional Outcome after First-Ever Ischaemic Stroke

We explored the relationship between acute ischaemic stroke (IS) early functional outcome and serum levels of homocysteine, vitamin B12, and D in a noninterventional prospective clinical study. We enrolled 50 patients with first-ever IS and performed laboratory tests and functional assessment at three time points: on admission and three and six months after stroke. Modified Rankin Scale (mRS), NIHSS scale, and Barthel index (BI) scores were assessed in all participants by trained examiner blinded to laboratory data. Patients did not receive treatment that might alter laboratory data. Admission NIHSS correlated with homocysteine levels (r = 0.304, p < 0.05), B12 level (r = −0.410, p < 0.01), and vitamin D levels (r = −0.465, p < 0.01). Functional outcome measures (BI and mRS) did not significantly correlate with homocysteine and vitamin D3 levels at 3 and 6 months. However, a positive correlation with vitamin B12 levels was detected for BI both at 3 and 6 months and mRS at 6 months. Higher serum vitamin B12 levels were associated with better functional outcome at follow-up.

The Effects of Folate Supplementation on Carotid Intima-Media Thickness and Metabolic Status in Patients with Metabolic Syndrome

BACKGROUND

This study was carried out to evaluate the effects of folate supplementation on carotid intima-media thickness (CIMT) and metabolic status among patients with metabolic syndrome (MetS).

METHODS

This randomized, double-blind, placebo-controlled trial was conducted among 60 patients with type 2 diabetes mellitus and coronary heart disease. They were all overweight in the age range 40-85 years. Participants were randomly divided into 2 groups: group A (n = 30) received 5 mg folate supplements and group B (n = 30) received placebo for 12 weeks.

RESULTS

Folate supplementation resulted in a significant reduction in maximum levels of left CIMT (-0.05 ± 0.13 vs. +0.02 ± 0.11 mm, p = 0.01) compared with the placebo. Changes in fasting plasma glucose (-2.2 ± 37.5 vs. +30.2 ± 65.8 mg/dl, p = 0.02), serum insulin concentration (-2.0 ± 10.7 vs. +3.0 ± 7.6 µIU/ml, p = 0.04) and homeostasis of assessment-estimated insulin resistance (-0.6 ± 2.3 vs. +0.9 ± 2.3, p = 0.01) in supplemented patients were significantly different from those of patients in the placebo group. Changes in serum triglycerides (p = 0.04), high-density lipoprotein-cholesterol (p = 0.001), high sensitivity C-reactive protein (p = 0.01) and plasma nitric oxide concentrations (p < 0.001) were significantly different between the supplemented patients and placebo group.

CONCLUSIONS

Overall, 5 mg/day folate supplementation for 12 weeks among patients with MetS had beneficial effects on CIMT and the metabolic status.

Diabetes and associated complications in the South Asian population

The rising prevalence of diabetes in South Asians has significant health and economic implications. South Asians are predisposed to the development of diabetes due to biologic causes which are exacerbated by lifestyle and environmental factors. Furthermore, they experience significant morbidity and mortality from complications of diabetes, most notably coronary artery disease, cerebrovascular disease, and chronic kidney disease. Therefore, understanding the pathophysiology and genetics of diabetes risk factors and its associated complications in South Asians is paramount to curbing the diabetes epidemic. With this understanding, the appropriate screening, preventative and therapeutic strategies can be implemented and further developed. In this review, we discuss in detail the biologic and lifestyle factors that predispose South Asians to diabetes and review the epidemiology and pathophysiology of microvascular and macrovascular complications of diabetes in South Asians. We also review the ongoing and completed diabetes prevention and management studies in South Asians.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Prevalence of MTHFR C677T single nucleotide polymorphism in genetically isolated populations in Jordan

Methylenetetrahydrofolate reductase (MTHFR) C677T single nucleotide polymorphism is a major inherited risk factor of venous thromboembolism. We sought to determine its prevalence in genetically isolated populations of Chechens and Circassians in Jordan. The MTHFR C677T mutation was analyzed from blood samples taken from 120 random unrelated Chechens and 72 Circassians. The prevalence of the MTHFR mutation in the Chechen population was 27.5% (allele frequency 15%); the prevalence among the Circassians was 50% (allele frequency 29.2%). The prevalence in the Chechen population is similar to that in Jordan and other world populations, but it is higher in the Circassian population. This study will contribute to understanding the interaction between genetic and environmental risk factors underlying thrombosis and will be useful in deciding which genetic variants should be tested in a clinical genetic testing service.

Detailed analysis of gene polymorphisms associated with ischemic stroke in South Asians

The burden of stroke is disproportionately high in the South Asian subcontinent with South Asian ethnicity conferring a greater risk of ischemic stroke than European ancestry regardless of country inhabited. While genes associated with stroke in European populations have been investigated, they remain largely unknown in South Asians. We conducted a comprehensive meta-analysis of known genetic polymorphisms associated with South Asian ischemic stroke, and compared effect size of the MTHFR C677T-stroke association with effect sizes predicted from homocysteine-stroke association. Electronic databases were searched up to August 2012 for published case control studies investigating genetic polymorphisms associated with ischemic stroke in South Asians. Pooled odds ratios (OR) for each gene-disease association were calculated using a random-effects model. We identified 26 studies (approximately 2529 stroke cases and 2881 controls) interrogating 33 independent genetic polymorphisms in 22 genes. Ten studies described MTHFR C677T (108 with TT genotype and 2018 with CC genotype) -homocysteine relationship and six studies (735 stroke cases and 713 controls) described homocysteine-ischemic stroke relationship. Risk association ORs were calculated for ACE I/D (OR 5.00; 95% CI, 1.17–21.37; p = 0.03), PDE4D SNP 83 (OR 2.20; 95% CI 1.21–3.99; p = 0.01), PDE4D SNP 32 (OR 1.57; 95% CI 1.01–2.45, p = 0.045) and IL10 G1082A (OR 1.44; 95% CI, 1.09–1.91, p = 0.01). Significant association was observed between elevated plasma homocysteine levels and MTHFR/677 TT genotypes in healthy South Asians (Mean difference (ΔX) 5.18 µmol/L; 95% CI 2.03–8.34: p = 0.001). Our results demonstrate that the genetic etiology of ischemic stroke in South Asians is broadly similar to the risk conferred in Europeans, although the dataset is considerably smaller and warrants the same clinical considerations for risk profiling.

Genetic and environmental influences on total plasma homocysteine and its role in coronary artery disease risk

BACKGROUND

Elevated levels of total plasma homocysteine are a risk factor for atherosclerotic disease.

AIMS

The rationale behind this study is to explore the correlation between degree and site of coronary lesion and hyperhomocysteinemia in Lebanese CAD patients and assess environmental and genetic factors for elevated levels of total plasma homocysteine.

METHODS

A total of 2644 patients were analyzed for traditional CAD risk factors. Logistic regression was performed to determine the association of hyperhomocysteinemia with degree and site of coronary lesions controlling for risk factors. Environmental and genetic factors for hyperhomocysteinemia were analyzed by logistic regression using a candidate gene approach.

RESULTS

Traditional risk factors were correlated with stenosis. Hyperhomocysteinemia associated with increased risk of overall stenosis, and risk of mild and severe occlusion in major arteries. Hyperhomocysteinemia and hypertension were highly correlated suggesting that hyperhomocysteinemia acts as a hypertensive agent leading to CAD. Diuretics and genetic polymorphisms in MTHFR and SLCO1B1 were associated with hyperhomocysteinemia.

CONCLUSIONS

Hyperhomocysteinemia is a medical indicator of specific vessel stenosis in the Lebanese population. Hypertension is a major link between hyperhomocysteinemia and CAD occurrence. Genetic polymorphisms and diuretics' intake explain partly elevated homocysteine levels. This study has important implications in CAD risk prediction.

Effect of folic acid supplementation on the progression of carotid intima-media thickness: a meta-analysis of randomized controlled trials

OBJECTIVES

We conducted a meta-analysis of relevant randomized trials to assess whether folic acid supplementation reduces the progression of atherosclerosis as measured by carotid intima-media thickness (CIMT).

METHODS

This analysis included 2052 subjects from ten folic acid randomized trials with the change in CIMT reported as one of the end points. Summary estimates of weighted mean differences (WMDs) and 95% CIs were obtained by using random-effect models. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity.

RESULTS

Our analysis showed that folic acid supplementation significantly reduces the progression of CIMT (WMD: -0.04 mm; 95%CI: -0.07, -0.02; P<0.001), particularly in subjects with chronic kidney disease (CKD) (WMD: -0.16 mm; 95%CI: -0.26, -0.07; P=0.0006) or high cardiovascular disease (CVD) risk (WMD: -0.05 mm; 95%CI: -0.11, 0.00; P=0.06) but not in subjects who were generally healthy with only elevated homocysteine concentrations (WMD:0.00 mm; 95%CI: -0.01, 0.01; P=0.35). Furthermore, meta-regression analysis of the data showed that the baseline CIMT levels (P=0.011) and the percent reduction of homocysteine (P<0.001) were positively related to the effect size. Consistently, a greater beneficial effect was seen in those trials with baseline CIMT levels ≥0.8 mm (WMD: -0.14 mm; 95%CI: -0.19, -0.08; P<0.0001), and a reduction in the homocysteine concentration ≥30% (WMD: -0.22 mm; 95%CI: -0.38, -0.06; P=0.009). In the corresponding comparison groups, the effect sizes were attenuated and insignificant.

CONCLUSIONS

Our findings indicate that folic acid supplementation is effective in reducing the progression of CIMT, particularly in subjects with CKD or high CVD risk and among trials with higher baseline CIMT levels or a larger homocysteine reduction.

Guidelines for the primary prevention of stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

This guideline provides an overview of the evidence on established and emerging risk factors for stroke to provide evidence-based recommendations for the reduction of risk of a first stroke.

METHODS

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association (AHA) Stroke Council Scientific Statement Oversight Committee and the AHA Manuscript Oversight Committee. The writing group used systematic literature reviews (covering the time since the last review was published in 2006 up to April 2009), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations using standard AHA criteria (Tables 1 and 2). All members of the writing group had the opportunity to comment on the recommendations and approved the final version of this document. The guideline underwent extensive peer review by the Stroke Council leadership and the AHA scientific statements oversight committees before consideration and approval by the AHA Science Advisory and Coordinating Committee.

RESULTS

Schemes for assessing a person's risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic predisposition. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, excessive alcohol consumption, drug abuse, use of oral contraceptives, sleep-disordered breathing, migraine, hyperhomocysteinemia, elevated lipoprotein(a), hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

CONCLUSIONS

Extensive evidence identifies a variety of specific factors that increase the risk of a first stroke and that provide strategies for reducing that risk.

Deciphering the causes of cardiovascular and other complex diseases in populations: achievements, challenges, opportunities, and approaches

This paper provides an overview of key achievements of the Framingham Heart Study and identifies areas and approaches for future research in cardiovascular disease epidemiology and prevention. There is a need for a range of different studies using diverse designs (i.e. case-control, cohort, multi-community, birth cohort, family-based cohorts and randomized trials) in different settings and involving multiple ethnic groups. Incorporation of a range of new disciplines, such as genetics, behavioural sciences, social epidemiology, measures of the environment, geography, and health policy are required to understand the root determinants of cardiovascular diseases.

The association between methylene-tetrahydrofolate reductase gene polymorphism and lung cancer risk

This study aimed to determine the relation between methylene-tetrahydrofolate reductase (MTHFR) gene polymorphism and lung cancer risk and the frequency of this polymorphism. The study involved 64 lung cancer patients (the study group) with definitive diagnosis and 61 noncancerous subjects (the control group). MTHFR C677T and A1298C mutation analysis was made using DNA isolated from peripheric blood and multiplex PCR and reverse hybridization strip test. Eighty-four percent of the patients were male. The age, gender, and history of alcohol use of the patients and control group were statistically similar. While MTHFR 677T and 677C allele frequency was 0.33 and 0.67 in the patients respectively, it was 0.29 and 0.71 in the control group. The frequencies of MTHFR 1298C and 1298A were 0.33 and 0.67 in the patients, and it was 0.31 and 0.69 in the control group respectively. When MTHFR 677TT and 677CT genotypes were compared with 677CC genotype, lung cancer risk was 2.4 times higher in the 677TT genotype. When MTHFR 1298AC and 1298CC genotypes were compared with 1298AA genotype, lung cancer risk was 1.5 times higher in 1298CC genotype. According to the results, allele frequency of homozygote T and C was high in lung cancer patients. It was 3.05 and 1.29 times higher in smokers than in non-smokers, and 3.05 and 1.64 times higher in males than in females; 3.0 and 2.44 times higher in those with non-small cell lung cancer than in those with small-cell lung cancer.

Comprehensive Analysis of Genomic Variation in the LPA Locus and Its Relationship to Plasma Lipoprotein(a) in South Asians, Chinese, and European Caucasians

Background— Functional copy number variation in the apolipoprotein(a) gene ( LPA ) underlies a variable number of protein kringle domains repeated in tandem in the lipoprotein(a) [Lp(a)] particle. Genomic analysis of LPA , including both single-nucleotide polymorphisms (SNPs) and kringle IV type 2 (KIV-2) copy number, has yet to be performed.

Methods and Results— First, we genotyped 49 SNPs within 100 kb of LPA in a multiethnic sample comprising South Asians (n=330), Chinese (n=304), and European Caucasians (n=272). Second, using quantitative polymerase chain reaction, we estimated the KIV-2 copy number in each sample. European Caucasians had the lowest KIV-2 copy number but displayed the strongest correlation between KIV-2 copy number and plasma Lp(a) concentration ( r s =−0.31, P =4.2�10 −7 ). SNP rs10455872, only prevalent in European Caucasians, was strongly associated with both plasma Lp(a) concentration ( P =4.2�10 −29 ) and KIV-2 copy number ( P =7.2�10 −5 ). LPA SNP rs6415084, within the same haplotype block as the KIV-2 variation, was significantly associated with both Lp(a) concentration and KIV-2 copy number in the same direction in all 3 ethnicities [Lp(a), P =5.3�10 −7 ; KIV-2, P =2.6�10 −4 ]. SNPs and KIV-2 copy number together explain a larger proportion of variation in plasma Lp(a) concentrations in European Caucasians (36%) than in Chinese (27%) or South Asians (21%).

Conclusions— LPA SNPs are in linkage disequilibrium with KIV-2 copy number, but KIV-2 copy number explains an increment in plasma Lp(a) variation over SNPs alone. Thus, both SNPs and KIV-2 copy number should be included in future genetic epidemiology studies of Lp(a).

Multi-ethnic genetic association study of carotid intima-media thickness using a targeted cardiovascular SNP microarray

BACKGROUND AND PURPOSE

Identification of subclinical atherosclerosis by ultrasonographic measurement of carotid intima-media thickness (IMT) is a validated tool, in conjunction with traditional risk factors, for clinical assessment of cardiovascular disease risk. IMT has also been recognized as a quantitative measure of cardiovascular disease progression in asymptomatic individuals, and many candidate gene association studies have attempted to identify genetic variants associated with interindividual differences in IMT with limited success. We sought to test the association between subclinical atherosclerosis measured by IMT and approximately 50,000 SNPs, densely mapping approximately 2100 genes found on the gene-centric Illumina cardiovascular disease beadchip in a multi-ethnic population-based sample.

METHODS

IMT was measured by B-mode ultrasound and DNA was collected from a population-based sample of South Asian (n=328), Chinese (n=302), and European Caucasian (n=268) participants. Genetic association was measured using multivariate linear regression including adjustment for covariates.

RESULTS

The most robust association across all models tested was observed for a SNP (rs3791398) in histone deacetylase 4 (HDAC4; P=1.8e-5 to P=3.6e-5), while another strong association signal was observed with natriuretic peptide receptor a/guanylate cyclase A (NPR1) (rs10082235, P=5.4e-5). Seven of 13 previously reported functional candidate genes contained a SNP that was marginally associated (0.01 < P < or = 0.05).

CONCLUSION

This initial multi-ethnic high-density association study of carotid IMT suggests some novel loci requiring further evaluation in follow-up studies.

Asymmetric dimethylarginine reference intervals determined with liquid chromatography-tandem mass spectrometry: results from the Framingham offspring cohort

BACKGROUND

Accumulating evidence links higher circulating asymmetric dimethylarginine (ADMA) to greater risk of cardiovascular disease (CVD). Relatively small differences in ADMA concentrations between healthy individuals and those with disease underscore the need to formulate reference intervals that may aid risk stratification of individuals.

METHODS

We formulated reference intervals for plasma ADMA concentrations using a community-based reference sample from the Framingham Offspring Study consisting of 1126 nonsmoking individuals [mean (SD) age 56 (9) years; 60% women] who were free of clinical CVD, hypertension, diabetes, and obesity and who attended a routine examination at which ADMA was assayed. ADMA concentrations were determined using a validated tandem mass spectrometry-liquid chromatography assay.

RESULTS

In the study sample, the mean ADMA concentration was 0.52 (0.11) micromol/L, and the reference limits were 0.311 and 0.732 (2.5th and 97.5th percentile). The sex-specific reference limits were 0.310 and 0.745 in men and 0.313 and 0.721 micromol/L in women. In multivariable regression analysis, ADMA plasma concentrations were positively correlated with age and total plasma homocysteine (both P < 0.001).

CONCLUSIONS

Reference limits calculated for circulating ADMA in our large community-based healthy reference sample confirm the previous observation of a relatively narrow distribution of concentrations. This suggests a tight physiological control of ADMA plasma concentrations, presumably by dimethylarginine dimethylaminohydrolase (DDAH) metabolism of ADMA.

Ethnicity does not affect the homocysteine-lowering effect of B-vitamin therapy in Singaporean stroke patients

BACKGROUND AND PURPOSE

Increased total homocysteine (tHcy) is a risk factor for stroke. This study examines whether the efficacy of B-vitamins in reducing tHcy is modified by ethnicity in a Singaporean ischemic stroke population.

METHODS

505 patients (419 Chinese, 41 Malays and 45 Indians) with ischemic stroke were randomized to receive placebo or B-vitamins. Fasting blood samples collected at baseline and 1 year were assayed for tHcy. MTHFR polymorphisms were genotyped.

RESULTS

Ethnicity did not independently determine tHcy at baseline. The magnitude of tHcy reduction by B-vitamin treatment was consistent across ethnic groups (Chinese -3.8+/-4.5, Malay -4.9+/-4.2, and Indian -3.3+/-3.6 micromol/L) despite ethnic differences in MTHFR genotype and baseline folic acid (FA) and vitamin B(12) (vitB(12)) concentrations.

CONCLUSIONS

Ethnicity does not appear to affect the tHcy-lowering effect of B-vitamins, despite differences in dietary intake and prevalence of MTHFR polymorphisms. This suggests that the effect of B-vitamins in lowering tHcy is generalizable across Asian populations. However, due to relatively small numbers of non-Chinese studied, confirmation in other populations is required.

Hyperhomocysteinemia, intima-media thickness and C677T MTHFR gene polymorphism: a correlation study in patients with cognitive impairment

OBJECTIVE

Intima-media thickness (IMT) seems associated with risk of Alzheimer disease (AD). Homocysteine (hcy) is a risk factor for vascular diseases and dementia. This study aimed at investigating the possible relationship among IMT, plasma hcy and C677T methylentetrahydrofolate reductase (MTHFR) polymorphism in relation to cognitive status.

METHODS

Sixty-three patients with cognitive impairment and 64 controls underwent biochemical, neuropsychological and carotid ultrasound assessment.

RESULTS

After age and folate adjustment, plasma hcy correlated with both Mini Mental State Examination (MMSE) score (r=-0.7, p<0.01) and IMT (r=0.7, p<0.01). Among patients with cognitive impairment, carriers of TT677 MTHFR genotype had plasma hcy (p<0.001) and IMT (p<0.01) values higher than non carriers. Furthermore, multiple regression analysis showed that MMSE scores were associated with plasma hcy (beta=-0.3, p=0.01), IMT (beta=-0.3, p=0.01) and TT677 MTHFR genotype (beta=-0.3, p=0.02). Structural equation modelling showed that the relation between hcy levels and MMSE score was partly direct (parameter estimate=-0.6; p=0.01) and partly mediated by IMT values (parameter estimate=-0.4; p=0.03). Finally, IMT resulted associated with hypertension (parameter estimate=0.8; p<0.0001).

CONCLUSION

Our findings suggest that TT677 MTHFR genotype promotes plasma homocysteine increase which in turn may favour intima-media thickening in patients with cognitive impairment. Hcy may promote neuronal damage through multiple mechanisms, including a micro-vascular damage, mediated by IMT increase, and a direct neuro-toxic effect.

Measuring subclinical atherosclerosis: is homocysteine relevant?

OBJECTIVES

We systematically reviewed published studies looking at the relationship between total serum homocysteine (tHcy) and subclinical markers of atherosclerosis, such as carotid intimal-medial thickness (C-IMT), coronary artery calcium (CAC) and ankle-brachial index (ABI) in asymptomatic individuals. We analyzed these studies to examine this relationship as well as to guide future avenues of investigation by identifying studies that will help in the inclusion of tHcy levels in current guidelines on atherosclerotic disease management.

BACKGROUND

tHcy has been known to be associated with clinically evident atherosclerotic disease. However, tHcy is not incorporated in current guidelines for diagnosis of subclinical disease in high-risk asymptomatic individuals.

METHODS

We searched online databases (e.g., PUBMED, MEDLINE) for published articles assessing the relationship between tHcy and C-IMT, CAC and ABI. We limited the studies to asymptomatic populations, and excluded any study including symptomatic patients or individuals with a history of coronary, peripheral or cerebrovascular disease.

RESULTS

A systemic review of 19 articles revealed a significant association between elevated levels of tHcy and subclinical markers of atherosclerosis in asymptomatic individuals in most studies. Mean tHcy levels were consistently found to be higher in men compared to women. A total of 12 studies showed a significant association between tHcy and other risk markers of atherosclerosis, even after adjusting for age, sex and conventional risk factors. There were seven studies in unique populations that showed no significant relationship. We also observed that studies lowering baseline tHcy levels did not lead to an improvement in C-IMT, CAC or ABI scores. This might indicate that tHcy has a stronger role as a marker of atherosclerotic disease than as a risk factor for the same.

CONCLUSIONS

Based on our review, we conclude that there is a significant association between the subclinical atherosclerotic process and tHcy, and it shows potential as a cheap marker for risk stratification of asymptomatic patients. However, future studies further elucidating this association and elaborating the exact role of tHcy in the atherosclerotic disease process are required. The results of these studies suggest the incorporation of plasma tHcy levels in future risk reduction protocols for identification of individuals at higher risk of atherosclerotic events, and thus to categorize them for more aggressive treatment with established preventive and therapeutic measures.

Interrelation of saturated fat, trans fat, alcohol intake, and subclinical atherosclerosis

BACKGROUND

Intake of saturated fat, trans fat, and alcohol alter cardiovascular disease risk, but their effect on subclinical atherosclerosis remains understudied.

OBJECTIVE

The objective was to examine and quantify the interrelation of saturated fat, trans fat, alcohol intake, and mean carotid artery intimal medial thickness (IMT).

DESIGN

We conducted a population-based, cross-sectional study among 620 persons of Aboriginal, South Asian, Chinese, or European origin aged 35-75 y, who had lived in Canada for >or=5 y. Mean IMT was calculated from 6 well-defined segments of the right and left carotid arteries with standardized B-mode ultrasound, and saturated fat, trans fat, and alcohol intakes were measured with validated food-frequency questionnaires.

RESULTS

For every 10-g/d increase in saturated fat intake, IMT was 0.03 mm higher (P=0.01) after multivariate adjustment. A 1-g/d higher intake of trans fat was associated with a 0.03-mm higher IMT (P=0.02) after multivariate adjustment. The ratio of polyunsaturated to saturated fat (P:S) was inversely associated with IMT after multivariate adjustment (change in IMT: -0.06 mm; P<0.01). Saturated and trans fat intakes were independently associated with IMT thickness (change in IMT: 0.03 mm; P<0.01 and 0.02, respectively; P for interaction=0.01). Polyunsaturated, monounsaturated, cholesterol, and total fat intakes were unrelated to IMT. The relation between saturated fat intake and IMT strengthened (beta=0.0066, P<0.001) in persons who never or rarely consumed alcohol as compared with moderate or heavy drinkers (beta=0.0001, P=0.79, P for interaction=0.01).

CONCLUSION

Higher habitual intakes of saturated and trans fats are independently associated with increased subclinical atherosclerosis, and alcohol intake may attenuate the relation between saturated fat and subclinical atherosclerosis.

Associations of methylenetetrahydrofolate reductase C677T polymorphism with markers of subclinical atherosclerosis: the Cardiovascular Risk in Young Finns Study

OBJECTIVE

To study whether the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism or serum homocysteine concentration is associated with carotid artery intima media thickness (IMT), carotid artery compliance (CAC) or brachial artery flow mediated dilatation (FMD) in a healthy Finnish adult population.

METHODS

Cross-sectional data obtained in 2001 for the Cardiovascular Risk in Young Finns Study were used. Carotid artery IMT, CAC and brachial FMD were measured by ultrasound and serum homocysteine concentrations using a commercial immunoassay kit. We studied 1,440 subjects (aged 24-39 years). Genotyping was performed using the 5' nuclease TaqMan assay.

RESULTS

Homocysteine values differed between genotypes in women and men (ANOVA, p<0.001 for both sex groups): the genotype raised values in the order of CC, CT, TT. There was a significant difference in CAC values between the MTHFR genotypes in men (ANOVA, p = 0.008), and the CC genotype had the lowest values. In multivariate linear regression analysis adjusted for other major coronary risk factors (e.g. age, smoking, body mass index, systolic blood pressure, C-reactive protein), the association remained significant (R (2) = 25.8 %, beta = 0.091; p = 0.02). Homocysteine level was directly associated with CAC in the whole population (R (2) = 18.0 %, beta = 0.012; p = 0.014) and in women (R (2) = 9.3%, beta = 0.02; p = 0.013), but not in men (R (2) = 15.2 %, beta = 0.004; p = 0.444). We found no association between homocysteine level or the MTHFR polymorphism and carotid IMT or brachial artery FMD.

CONCLUSIONS

The findings suggest that the MTHFR polymorphism does not influence IMT or FMD, but that the T allele may have an effect on CAC in men.

Circulating homocysteine and large arterial stiffness and thickness in a population-based sample of middle-aged and elderly men

Elevated plasma homocysteine (tHcy) is considered as a risk factor for cardiovascular events, and has been associated with arterial stiffness and subclinical atherosclerosis in subjects with classical cardiovascular risk factors. The aim of this study is to investigate the association of plasma tHcy with functional and structural changes in the large arteries by measuring aortic pulse-wave velocity (PWV) and carotid artery intima-media thickness (CIMT). In a population-based sample of 376 middle-aged and elderly men, tHcy levels were measured by using fluorescence polarization immunoassay. Aortic stiffness was assessed non-invasively by measuring carotid-femoral PWV with the use of applanation tonometry. CIMT was measured by ultrasonography. We used multivariate linear regression analysis with the log-transformed value of tHcy as the determinant, and aortic PWV and CIMT as outcomes. In the univariate model, PWV increased with increasing tHcy concentration; PWV increased by 2.64 m/s (95% confidence interval (CI) 1.74; 3.54) per unit change in log tHcy. After adjustment for confounders, no statistically significant association remained; PWV increased by 0.42 m/s (95% CI -0.27; 1.11) per unit change in log tHcy. Furthermore, in the univariate model, CIMT increased significantly with increasing tHcy concentration; CIMT increased by 0.19 mm (95% CI 0.11; 0.26) per unit increase log tHcy. This association was attenuated and did not remain significant after additional adjustment for age and cardiovascular confounders (beta=0.06 (95% CI -0.01; 0.13)). The results of this study do not support the presence of an independent relationship between circulating tHcy levels and large artery stiffness and thickness.

Role of MTHFR polymorphisms and folate levels in different phenotypes of sporadic colorectal cancers

BACKGROUND AND AIMS

By altering both DNA methylation and nucleotide synthesis, folate metabolism is thought to contribute to colorectal carcinogenesis. We examined the role of folate metabolism in three different phenotypes of sporadic colorectal cancers (CRCs), phenotypes that were classified by the status of microsatellite instability (MSI) and chromosomal instability (CIN): MSI-H, microsatellite stability (MSS)/aneuploidy, and MSS/diploid.

PATIENTS AND METHODS

A total of 195 sporadic colorectal tumors and another 195 age- and gender-matched healthy volunteers in Taipei-Veteran General Hospital and Taipei City Hospital were collected. We analyzed for MTHFR (methylenetetrahydrofolate reductase) polymorphisms (C677T, A1297C), folate, and vitamin B(12) levels. We determined MSI status and DNA ploidy with fluorescent polymerase chain reaction and flow cytometry. Relations between clinicopathological variables and molecular variables were analyzed by chi (2) tests (with Yates' correction) for categorical variables and Student's t test for numerical variables.

RESULTS

Folate levels (5.02+/-4.43 ng/ml) were significantly lower in cancer patients than in controls (7.22+/-4.46 ng/ml). Vitamin B(12) level was similar between cancer patients and controls. The frequency of the TT genotype of MTHFR C627T (12.3%) was slightly higher than controls (8.2%), but it did not reach statistical significance (p=0.174). Within the low-folate group (<5 ng/ml), the frequency of the TT genotype in cancer patients (14.4%) was significantly higher than in controls (4.6%). Sixteen patients who had MSI-H CRC (8.2%) had a significantly higher frequency of TT MTHFR (37.5%) and lower folate levels (3.56+/-2.41 ng/ml) than patients with MSS tumors (10.1%, 5.14+/-3.72 ng/ml). Patients with MSS/aneuploid tumors had significantly lower folate levels (4.50+/-3.06 ng/ml) than those with MSS/diploid tumors (6.69+/-4.73 ng/ml).

CONCLUSION

Folate deficiency and the MTHFR genetic polymorphism play an important role in colorectal carcinogenesis, including MSI and CI.

SYNOPSIS

Folate metabolism plays an important role in colorectal carcinogenesis. We demonstrate that patients with MSI-H tumors had higher frequency of TT MTHFR C627T (37.5%), and patients with MSS/aneuploid tumor had lower folate level (4.50+/-3.06 ng/ml).

Dietary measures and exercise training contribute to improvement of endothelial function and atherosclerosis even in patients given intensive pharmacologic therapy

PURPOSE

Atherosclerosis contributes to cardiovascular mortality and morbidity even with aggressive lipid management. Our objective is to determine whether a combined pharmacological and lifestyle intervention can improve atherosclerosis.

METHODS

We conducted a 2-year observational study at a specialized clinic in a tertiary care hospital. One hundred fifty-six subjects with coronary disease were enrolled in an intensive pharmacological management and lifestyle measures (including counseling and exercise training) program designed to reach specific targets. The main outcome measures were carotid intima media thickness and plaque area; brachial artery flow-mediated dilation; nitroglycerin-mediated dilation; flow-mediated dilation-nitroglycerin-mediated dilation ratio; laboratory parameters including lipids, glucose, creatinine, and homocysteine; and physical fitness.

RESULTS

At completion, there were improvements in lipids and physical fitness. There were no overall changes in flow-mediated dilation, nitroglycerin-mediated dilation, or carotid intima media thickness in the entire cohort. However, multivariate logistic regression showed that dietary and exercise variables, such as increasing fiber intake and reducing body weight and body fat percentage, were independent predictors of improvements in endothelial function and carotid plaque burden.

CONCLUSIONS

Even in the setting of intensive pharmacological therapy, lifestyle interventions, including exercise training and dietary changes, are important determinants of improved endothelial function and atherosclerosis.

Carotid intima-media thickness in coronary slow flow: relationship with plasma homocysteine levels

BACKGROUND AND OBJECTIVE

Coronary slow-flow phenomenon is characterized by delayed opacification of coronary vessels in a normal coronary angiogram. Although clinical and pathological features have been previously described, the underlying pathophysiology has not been fully elucidated. Thus, it still remains to be determined whether either microvascular or epicardial diffuse atherosclerotic disease is related to slow flow. In this study, we aimed to determine the carotid artery intima-media thickness, which is a marker of atherosclerosis in patients with coronary slow flow, and its possible relationship with the total homocysteine level.

METHOD

The study population consisted of 88 patients who underwent coronary angiography because of typical and quasi-typical symptoms of angina. Forty-four patients with angiographically proven coronary slow flow and 44 individuals with normal coronary flow pattern with similar risk profiles were enrolled in the study. Coronary flow patterns of the latter were determined by the thrombolysis in myocardial infarction frame count method. Intima-media thickness was measured by recording ultrasonographic images of both the left and the right common carotid artery with a 12-MHz linear array transducer. Plasma homocysteine, folate and B12 levels were measured from blood samples.

RESULTS

Plasma homocysteine levels (mumol/l) and carotid intima-media thickness (mm) of patients with coronary slow flow were found to be significantly higher than that of controls (12.4+/-4.9 vs. 8.5+/-2.8, P=0.0001; 0.75+/-0.08 vs. 0.69+/-0.06, P=0.0001, respectively). The plasma folate level (ng/ml) was lower in coronary slow-flow patients than in controls (13.8+/-4.4 vs. 16.5+/-5.6, P=0.014). The plasma homocysteine level was significantly positively correlated with the mean thrombolysis in myocardial infarction frame count and intima-media thickness of the carotid artery in correlation analysis (r=0.58, P=0.0001; r=0.41, P=0.0001; respectively).

CONCLUSION

Homocysteine levels and carotid intima-media thickness increased but folate levels decreased in patients with coronary slow flow. The present findings allow us to conclude that the possible disturbance in the metabolism of homocysteine in patients with coronary slow flow may have a role in the etiopathogenesis of this phenomenon by causing generalized atherosclerosis.

Differential effects of oral conjugated equine estrogen and transdermal estrogen on atherosclerotic vascular disease risk markers and endothelial function in healthy postmenopausal women

BACKGROUND

Recent studies have revealed that HRT may increase the risk for atherosclerotic vascular disease (ASVD).

METHODS

We investigated the effects of HRT via different administration routes on the markers for ASVD and endothelial function in healthy postmenopausal women. The oral HRT group (n=18) received conjugated equine estrogen 0.625 mg/day; the transdermal HRT group (n=18) received 17beta-estradiol (E2) gel 0.6 mg/day for 6 months. The control group (n=30) had no treatment for 6 months.

RESULTS

The C-reactive protein (CRP) rose from 0.129+/-0.116 to 0.752+/-0.794 mg/dl (P<0.01) in the oral HRT group but remained unchanged in the transdermal HRT and control groups. The flow-mediated vasodilation (FMD) in the brachial artery was increased significantly by HRT from 6.0% before oral HRT to 14.7% after oral HRT (P<0.001) and from 5.9% before transdermal HRT to 13.9% after transdermal HRT (P=0.001).

CONCLUSIONS

These data suggest that oral estrogen induces ASVD risk by increasing acute inflammation; however, transdermal estrogen avoids this untoward effect. Additionally, transdermal estrogen exerts a positive effect on endothelial function similar to that of oral estrogen. Therefore, the transdermal route might be favourable in terms of ASVD risks.

Genetic determinants of carotid ultrasound traits

Atherosclerosis is a complex disease with various intermediate phenotypes that are themselves complex and influenced by many factors. Through the use of carotid ultrasound techniques, the intermediate stages of vascular disease can be imaged and studied for association with potential genetic determinants. In this article we review the most recent available data (reports published since 2004) on the genetic determinants of atherosclerosis, as measured by one-, two-, and three-dimensional ultrasonography of the carotid arteries. In general, associations are disparate and modest. For intima-media thickness, promising associations have been found for both TNFRSF1A R92Q and PPARG P12A, but associations also differed in the same individuals depending on the specific ultrasound trait studied (eg, linear intima-media thickness versus total plaque volume in carotid arteries). Some of the challenging issues for future studies include accounting for gene-environment interactions, sex-specific associations, and the distinctiveness of different carotid ultrasound measures.

Relationship between genetic alterations and prognosis in sporadic colorectal cancer

Because chromosomal chromosomal instability (CIN) and microsatellite instability (MSI) are important genetic alterations in colorectal cancers, we classified the sporadic colorectal cancers (CRC) on the status of the CIN and MSI and explored their molecular profiles. A total of 213 colorectal tumors were collected for analysis of DNA ploidy, MSI, loss of heterozygosity (LOH), mutation of p53 (exons 5 to 9), Ki-ras (exons 1 and 2) and BRAF (V599E). Relationships between clinicopathological variables and molecular analyses were analyzed with the chi(2) test (Yates' correction). Kaplan-Meier survival curves were compared using log-rank test. Variables with p < 0.1 were entered into the Cox regression hazard model for multivariate analysis. High microsatellite instability (MSI-H) existed in 19 tumors (8.9%), which were more likely to be right-sided (31.6%) with poor differentiation (26.3%). Seventy-one (33.3%) tumors were diploid and 142 (66.7%) were aneuploid. Mutations in p53, Ki-ras and BRAF were found in 45.1%, 41.8% and 4.2% of tumors, respectively. Based on MSI, and CIN, 3 classes were defined: (i) High microsatellite instability MSI-H tumors: young age, high carcinoembryonic antigen (CEA) level, right colon, poorly differentiated, mucin production, high BRAF mutation, lower allelic loss and relatively good prognosis; (ii) Microsatellite stability (MSS) diploid tumors: right colon, poorly differentiated, less infiltrative tumor, mucin production, lower allelic loss and low p53, BRAF mutation; (iii) MSS aneuploid tumors: more infiltrative invasion, greater allelic loss and high p53 mutation. According to multivariate analysis, tumor stage and p53 mutation were significantly associated with disease progression. The MSS diploid and MSS aneuploid CRCs could be subtyped with p53 mutation and had different prognostic outcome and molecular profiles. The 4-year disease-free survival (DFS) of patients with MSS-diploid, wild-type p53 tumors was 67% and significantly higher than those of patients with MSS-diploid, mutant p53 CRC (30%, p = 0.003). The same trend was found in patients with MSS-aneuploid CRC(wild p53 vs. mutant p53, 64% vs. 41%, p = 0.009). We concluded that CIN, MSI and p53 mutation status might be used as a multiple parameter profile for the prognosis of sporadic colorectal cancer.

Sex differences in risk of lung cancer associated with methylene-tetrahydrofolate reductase polymorphisms

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the metabolism of folate and nucleotides needed for DNA synthesis and repair. Variations in MTHFR functions likely play roles in the etiology of lung cancer. The MTHFR gene has three nonsynonymous single nucleotide polymorphisms (i.e., C677T, A1298C, and G1793A) that have a minor allele frequency of >5%. We investigated the associations between the frequencies of MTHFR variant genotypes and risk of lung cancer in a hospital-based case-control study of 1,051 lung cancer patients and 1,141 cancer-free controls in a non-Hispanic White population. We found that compared with the MTHFR 1298AA genotype, the 1298CC genotype was associated with a significantly increased risk of lung cancer in women [(odds ratio (OR), 2.09; 95% confidence interval (95% CI), 1.32-3.29)] but not in men (OR, 0.95; 95% CI, 0.62-1.45). The MTHFR 677TT genotype was associated with a significantly decreased risk of lung cancer in women (OR, 0.60; 95% CI, 0.40-0.92) but not in men. No association was found between the MTHFR G1793A polymorphism and risk of lung cancer. Further analysis suggested evidence of gene-dietary interactions between the MTHFR C677T polymorphism and dietary intake of vitamin B6, vitamin B12, and methionine in women and evidence of gene-environment interactions between the MTHFR C677T and A1298C polymorphisms and tobacco smoking in men. In conclusion, the polymorphisms of MTHFR may contribute to the risk of lung cancer in non-Hispanic Whites and modify the risk associated with the dietary and environmental exposure in a sex-specific manner.

The value of studying gene-environment interactions in culturally diverse populations

Cardiovascular disease (CVD) is the leading cause of death and disability in the world. It is anticipated that CVD will reach pandemic proportions by the year 2020. Although the major causes of CVD are well documented and explain the majority of cardiovascular deaths, the prevalence of conventional cardiovascular risk factors vary substantially across diverse cultural groups. These differences are attributed to cultural or genetic differences or to interactions between genes and environmental factors. Substantial efforts have been invested in determining the genetic influences on CVD development, and it is unlikely that a single gene is responsible for the development of atherosclerotic CVD or its classical risk factors such as blood pressure or plasma lipids. It is more plausible that multiple genes, acting either alone or in concert with one another, which display effect modification in the presence of certain environmental factors, are modestly associated with CVD or its main risk factors. Following this hypothesis, studying populations with diversity in environmental factors may increase the discovery potential of gene-environmental interactions. In this brief review, the advantage of studying gene-environment interactions across heterogeneous groups with diverse lifestyles is discussed.

The genetics of stroke

PURPOSE OF REVIEW

Ischaemic stroke is a heterogeneous disease caused by different pathogenic mechanisms, of which small artery and large artery stroke are the most common. The identification of the genes involved is unclear. The likely candidate genes associated with stroke are those that are associated with matrix deposition (stromelysin-1, MMP3), inflammation (IL-6), and lipid metabolism (hepatic lipase, APOE, PON1) and clotting (factor V Leiden, fibrinogen).

RECENT FINDINGS

In this review we will only discuss those genes in which there has been a significant contribution to the understanding of stroke since October 2003.

SUMMARY

The published data were reviewed to determine the robustness of these associations and to examine whether there is any evidence of risk modification by factors such as smoking habit, known to be associated with stroke.