Association between elevated plasma total homocysteine and increased common carotid artery wall thickness

Associations of smoking status with carotid atherosclerosis: Mediated role of blood indexes and blood pressure

BACKGROUND AND AIMS

We aimed to assess the relationship between smoking status and carotid atherosclerosis (CA) with different manifestations and to explore the underlying mechanisms.

METHODS AND RESULTS

A total of 60,655 middle-aged and elderly participants were recruited. Logistic regression models were used to examine the association of smoking, various blood indexes [i.e., blood pressure, blood lipid, glycated hemoglobin (HbA1c) and homocysteine (Hcy)] with CA in different manifestations including carotid intima-media thickness (cIMT), plaques, and stenosis. Compared with nonsmokers, current smokers were associated with a higher prevalence of CA (OR = 3.48, 95%CI: 3.21-3.77) and its specific manifestations including cIMT (OR = 2.66, 95%CI: 2.42-2.93), plaques (OR = 3.67, 95%CI: 3.35-4.02) and stenosis (OR = 2.04, 95%CI: 1.64-2.54), after adjusting for potential confounders. Former smokers were also associated with an increased prevalence of CA (OR = 1.82, 95%CI: 1.54-2.14), cIMT (OR = 1.39, 95%CI: 1.14-1.69), plaques (OR = 2.04, 95%CI: 1.71-2.44) and stenosis (OR = 1.72, 95%CI: 1.18-2.51), but the associations were consistently weaker than that of the current smokers. The prevalence of CA, cIMT, plaques and stenosis among current smokers was positively associated with pack-years of cigarette smoking, partially mediated by SBP, HbA1c, TG, HDL-C and Hcy with a mediated proportion of 1.12%, 3.28%, 6.33%, 6.01% and 12.7%, respectively. Stratified analysis by sex showed a significantly higher CA among the current male smokers than females.

CONCLUSIONS

Current and former smoking was associated with increased carotid atherosclerosis, predominantly by current male smokers. A positive gradient between pack-years and carotid atherosclerosis among current smokers is partially mediated by SBP, HbA1c, TG, HDL-C and Hcy.

An unusual case of thrombotic storm in an amateur cricketer-a case report

BACKGROUND

Thrombotic storm is a series of acute to subacute thrombotic events that evolve over a few days to weeks and result in progressive thromboses at multiple sites. There is often a predisposing event to thromboses, such as trauma or infections. Prompt initiation of anti-coagulation can prove life-saving in such patients.

CASE REPORT

We describe a previously healthy young male who developed thromboses of the right axillary, brachial, radial, and ulnar arteries while bowling in a cricket match. A few hours later, he developed a stroke involving the right anterior and middle cerebral arteries. His thrombophilia workup was significant for elevated homocysteine levels. Although he had a delayed presentation to our hospital, he was treated with anticoagulation and given a trial of thromboembolectomy, which failed and he had to ultimately undergo a right below-elbow guillotine amputation.

CONCLUSION

Thrombotic storm should be recognized promptly in the Emergency Department and timely anticoagulation should be initiated.

Pathophysiological concepts and screening of cardiovascular disease in dialysis patients

Dialysis patients experience 10-20 times higher cardiovascular mortality than the general population. The high burden of both conventional and nontraditional risk factors attributable to loss of renal function can explain higher rates of cardiovascular disease (CVD) morbidity and death among dialysis patients. As renal function declines, uremic toxins accumulate in the blood and disrupt cell function, causing cardiovascular damage. Hemodialysis patients have many cardiovascular complications, including sudden cardiac death. Peritoneal dialysis puts dialysis patients with end-stage renal disease at increased risk of CVD complications and emergency hospitalization. The current standard of care in this population is based on observational data, which has a high potential for bias due to the paucity of dedicated randomized clinical trials. Furthermore, guidelines lack specific guidelines for these patients, often inferring them from non-dialysis patient trials. A crucial step in the prevention and treatment of CVD would be to gain better knowledge of the influence of these predisposing risk factors. This review highlights the current evidence regarding the influence of advanced chronic disease on the cardiovascular system in patients undergoing renal dialysis.

Non-Conventional Risk Factors: "Fact" or "Fake" in Cardiovascular Disease Prevention?

Cardiovascular diseases (CVDs), such as arterial hypertension, myocardial infarction, stroke, heart failure, atrial fibrillation, etc., still represent the main cause of morbidity and mortality worldwide. They significantly modify the patients' quality of life with a tremendous economic impact. It is well established that cardiovascular risk factors increase the probability of fatal and non-fatal cardiac events. These risk factors are classified into modifiable (smoking, arterial hypertension, hypercholesterolemia, low HDL cholesterol, diabetes, excessive alcohol consumption, high-fat and high-calorie diet, reduced physical activity) and non-modifiable (sex, age, family history, of previous cardiovascular disease). Hence, CVD prevention is based on early identification and management of modifiable risk factors whose impact on the CV outcome is now performed by the use of CV risk assessment models, such as the Framingham Risk Score, Pooled Cohort Equations, or the SCORE2. However, in recent years, emerging, non-traditional factors (metabolic and non-metabolic) seem to significantly affect this assessment. In this article, we aim at defining these emerging factors and describe the potential mechanisms by which they might contribute to the development of CVD.

Intima-media thickness: indicator of cardiovascular risk and measure of the extent of atherosclerosis

The measurement of intima-media thickness (IMT) of large superficial arteries, especially the carotid, using high-resolution B-mode ultrasonography has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and for assessing cardiovascular risk. IMT measurement obtained by ultrasonography correlates very well with pathohistologic measurements and the reproducibility of this technique is good. Population studies have shown a strong correlation between carotid IMT and several cardiovascular risk factors, and it has also been found to be associated with the extent of atherosclerosis and end-organ damage of high-risk patients. Therefore, increased carotid IMT is a measure of athero-sclerotic burden and a predictor of subsequent events. Because of its quantitative value, carotid IMT measurement is more and more frequently used in clinical trials to test the effects of different preventive measures, including drugs. More recently, there has been interest in the clinical use of this technique for detecting preclinical (asymptomatic) atherosclerosis and for identifying subjects at high risk. Measurement of carotid IMT could influence a clinician to intervene with medication and to use more aggressive treatment of risk factors in primary prevention, and in patients with atherosclerotic disease in whom there is evidence of progression and extension of atherosclerotic disease. For more extensive use of this method in clinical practice a consensus concerning the standardization of methods of measurement and precise definition of threshold between normal and pathologic IMT value is urgently needed.

Studies on the pathophysiology and genetic basis of migraine

Migraine is a neurological disorder that affects the central nervous system causing painful attacks of headache. A genetic vulnerability and exposure to environmental triggers can influence the migraine phenotype. Migraine interferes in many facets of people's daily life including employment commitments and their ability to look after their families resulting in a reduced quality of life. Identification of the biological processes that underlie this relatively common affliction has been difficult because migraine does not have any clearly identifiable pathology or structural lesion detectable by current medical technology. Theories to explain the symptoms of migraine have focused on the physiological mechanisms involved in the various phases of headache and include the vascular and neurogenic theories. In relation to migraine pathophysiology the trigeminovascular system and cortical spreading depression have also been implicated with supporting evidence from imaging studies and animal models. The objective of current research is to better understand the pathways and mechanisms involved in causing pain and headache to be able to target interventions. The genetic component of migraine has been teased apart using linkage studies and both candidate gene and genome-wide association studies, in family and case-control cohorts. Genomic regions that increase individual risk to migraine have been identified in neurological, vascular and hormonal pathways. This review discusses knowledge of the pathophysiology and genetic basis of migraine with the latest scientific evidence from genetic studies.

Serum level of homocysteine is correlated to carotid artery atherosclerosis in Chinese with ischemic stroke

OBJECTIVES

To investigate the relationship between serum level of homocysteine (Hcy) and carotid artery atheroscleosis (CAA).

METHODS

Both sides of the common carotid artery and internal carotid artery in 126 Chinese patients with ischemic stroke were measured by B-mode ultrasound. The patients were divided into groups: normal, A, B, C and D according to the severity of CAAs. With fasting serum, Hcy as well as folate, vitamin B(12) and lipids were detected. The mean +/- SD age was 64 +/- 13 years (range 39-87 years).

RESULTS

In a logistic regression model, the Hcy concentrations were associated with an elevated risk of CAAs independent of all traditional risk factors, and when CAAs became severer, the serum Hcy was higher. The levels of the normal group and A, B, C, D groups were 13.22 +/- 6.15 micromol/L, 16.29 +/- 9.81 micromol/l, 19.49 +/- 11.16 micromol/l, 27.21 +/- 17.47 micromol/l, and 24.14 +/- 8.64 micromol/l, respectively. Rank test showed a significant difference between normal and other groups (p<0.05). The levels of folate and vitamin B(12) were negatively correlated with the Hcy concentrations. Spearman correlation coefficient were -0.23 and -0.42 (p<0.05).

CONCLUSIONS

Hyperhomocysteinaemia is an independent risk factor of CAAs and the degree of CAAs is highly correlated with the level of Hcy in serum. The causes of hyperhomocysteinemia may be the result from the decrease in folate and vitamin B(12). Clinical trials are now required to evaluate the effect of treatment with these vitamins on the primary and secondary prevention of cerebral vascular diseases.

Nutrition and human health from a sex-gender perspective

Nutrition exerts a life-long impact on human health, and the interaction between nutrition and health has been known for centuries. The recent literature has suggested that nutrition could differently influence the health of male and female individuals. Until the last decade of the 20th century, research on women has been neglected, and the results obtained in men have been directly translated to women in both the medicine and nutrition fields. Consequently, most modern guidelines are based on studies predominantly conducted on men. However, there are many sex-gender differences that are the result of multifactorial inputs, including gene repertoires, sex steroid hormones, and environmental factors (e.g., food components). The effects of these different inputs in male and female physiology will be different in different periods of ontogenetic development as well as during pregnancy and the ovarian cycle in females, which are also age dependent. As a result, different strategies have evolved to maintain male and female body homeostasis, which, in turn, implies that there are important differences in the bioavailability, metabolism, distribution, and elimination of foods and beverages in males and females. This article will review some of these differences underlying the impact of food components on the risk of developing diseases from a sex-gender perspective.

Mesenteric vascular remodeling in hyperhomocysteinemia

Remodeling by its very nature implies synthesis and degradation of extracellular matrix components (such as elastin, collagen, and connexins). Most of the vascular matrix metalloproteinase (MMP) are latent because of the presence of constitutive nitric oxide (NO). However, during oxidative stress peroxinitrite (ONOO-) activates the latent MMPs and instigates vascular remodeling. Interestingly, in mesenteric artery, homocysteine (Hcy) decreases the NO bio-availability, and folic acid (FA, an Hcy-lowering agent) mitigates the Hcy-mediated mesentery artery dysfunction. Dimethylarginine dimethylaminohydrolase-2 (DDAH-2) and endothelial nitric oxide synthase (eNOS) increases NO production. The hypothesis was that the Hcy decreased NO bio-availability, in part, activating MMP, decreasing elastin, DDAH-2, eNOS and increased vasomotor response by increasing connexin. To test this hypothesis,the authors used 12-week-old C57BJ/L6 wild type (WT) and hyperhomocysteinemic (HHcy)-cystathione beta synthase heterozygote knockout (CBS+/-) mice. Blood pressure measurements were made by radio-telemetry. WT and MMP-9 knockout mice were administered with Hcy (0.67 mg/ml in drinking water). Superior mesenteric artery and mesenteric arcade were analyzed with light and confocal microscopy. The protein expressions were measured by western blot analysis. The mRNA levels for MMP-9 were measured by RT-PCR. The data showed decreased DDAH-2 and eNOS expressions in mesentery in CBS-/+ mice compared with WT mice. Immuno-fluorescence and western blot results suggest increased MMP-9 and connexin-40 expression in mesenteric arcades of CBS-/+ mice compared with WT mice. The wall thickness of third-order mesenteric artery was increased in CBS-/+ mice compared to WT mice. Hcy treatment increased blood pressure in WT mice. Interestingly, in MMP-9 KO, Hcy did not increase blood pressure. These results may suggest that HHcy causes mesenteric artery remodeling and narrowing by activating MMP-9 and decreasing DDAH-2 and eNOS expressions, compromising the blood flow, instigating hypertension, and acute abdomen pain.

Serum total homocysteine, folate, 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T genotype and subclinical atherosclerosis

OBJECTIVE

To determine the relationship of serum total homocysteine (tHcy), serum folate and 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T genotype with ultrasonic arterial wall measurements associated with subclinical atherosclerosis.

STUDY DESIGN

Cross-sectional analysis of 767 participants in an ongoing prospective study. Intima-media thickness (IMT) of the common carotid (IMTcc), IMT of the internal carotid including plaque when present (IMT(max)) and the sum of the thickest plaques present in both carotid and both common femoral bifurcations (total plaque thickness (TPT)) were measured using ultrasound.

RESULTS

People in the upper homocysteine quartile were more likely to have clinical cardiovascular disease (CVD) than those in the lowest three quartiles. They were also more likely to have plaques. The MTHFR 677C-->T genotype was not associated with any of the measures of subclinical atherosclerosis in either men or women but was the most important determinant of total homocysteine levels in men under 60 years of age.

CONCLUSIONS

Increased homocysteine levels but not MTHFR 677C-->T genotype, are associated with subclinical atherosclerosis and the presence of plaques. Our results indicate that measurements of blood levels of homocysteine and folate in people at intermediate risk for atherosclerotic CVD before symptoms occur, might improve risk stratification and facilitate the decision to provide folate/B vitamin intervention in primary prevention.

Homocysteine and carotid intima-media thickness in ischemic stroke patients are not correlated

INTRODUCTION

Hyperhomocysteinemia has been linked to cardiovascular morbidity and mortality by numerous authors. Whether this association is causal or not remains uncertain. The aim of the study was to investigate the association of hyperhomocysteinemia with the degree of carotid atherosclerosis in stroke patients.

METHODS

We studied 97 Greek patients in our stroke unit who were hospitalized as a result of ischemic stroke between March 2006 and May 2007. The patients were divided into two groups: the first (52 patients) included stroke patients with serum levels of homocysteine below 15 mumol/L, but in the second group (45 patients) serum homocysteine exceeded this value. We measured carotid intima-media thickness (cIMT) in all patients and correlated it with serum homocysteine.

RESULTS

The mean homocysteine concentration was 11.5 mumol/L in the first group and 21.5 mumol/L in the second group. Carotid IMT was 1.012 mm in the first group, and 1.015 mm in the second group, an insignificant difference. On the contrary, serum folate concentration was 21.3 nmol/L in the first group compared with 16.7 nmol/L in the second group (p < 0.001). VitB12 was 401 pmol/L in the first group and 340 pmol/L in the second group, a statistically significant difference (p < 0.001).

CONCLUSIONS

Serum levels of homocysteine were not correlated with cIMT in ischemic stroke patients. Both folate and vitB12 were decreased in hyperhomocysteinemic ischemic stroke patients.

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.

Augmentation index and carotid intima-media thickness are differently related to age, C-reactive protein and oxidized low-density lipoprotein

OBJECTIVE

Ageing, plasma circulating C-reactive protein (CRP), oxidized low-density lipoprotein (OxLDL) and homocysteine (Hcy) are associated with atherosclerosis. The aim of this study was to evaluate the relationship between age, inflammatory and oxidative stress-related markers with functional and structural changes of the arteries in asymptomatic persons.

METHODS

CRP, OxLDL and Hcy were measured in 175 clinically healthy subjects, aged 40-70 years. Ultrasonography and pulse wave analysis were used to measure carotid intima-media thickness (IMT) and augmentation index (AIx).

RESULTS

OxLDL was correlated with IMT (r = 0.24, P = 0.003), whereas CRP was correlated with AIx (r = 0.21, P = 0.005). No correlation was detected between Hcy and AIx or age-adjusted IMT. There was a significant association between AIx and age <or=50 years (r = 0.33; P = 0.001) and between IMT and age > 50 years (r = 0.40; P = 0.001). In stepwise regression analysis age, weight, white blood cell count, OxLDL, heart rate and timing of the reflected waveform adjusted for height were significantly and independently associated with IMT (R = 0.41; P < 0.001). At the same time, AIx as the dependent variable correlated positively with age, gender, CRP and mean arterial pressure, and negatively with heart rate, weight and height, in stepwise regression analysis (R = 0.63; P < 0.001).

CONCLUSION

The results of the present study showed that CRP, OxLDL, Hcy and age are not similarly related to AIx and IMT in asymptomatic persons. The results suggest that CRP and younger age are related to arterial stiffness, whereas OxLDL and older age become more important determinants of structural changes of the arteries in asymptomatic persons.

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.

Hyperhomocysteinemia and thrombosis: an overview

CONTEXT

Homocysteine, a sulfur-containing amino acid, absent in natural diets, is a metabolic intermediary in transmethylation and transsulfuration reactions. Such reactions are essential to normal cellular growth, differentiation, and function. Excess homocysteine is associated with vascular disease and related disorders.

OBJECTIVE

To review homocysteine metabolism, the pathogenesis and classification of hyperhomocysteinemia, and the published literature investigating the association of homocysteine and methylenetetrahydrofolate reductase defects with arterial and venous thromboembolism and related disorders. The role of vitamin supplementation in patients with hyperhomocysteinemia is addressed.

DATA SOURCES

Published medical and scientific literature. Articles addressing the objectives were selected and reviewed. Pertinent studies and conclusions were summarized, grouped, and contrasted.

CONCLUSIONS

The association of hyperhomocysteinemia and arterial and venous thrombosis is controversial. Severe hyperhomocysteinemia is associated with atherosclerosis. The effect of mild hyperhomocysteinemia is less certain. Coinheritance of methylenetetrahydrofolate reductase defects and factor V Leiden is likely to increase the risk of venous thromboembolism. The association of methylenetetrahydrofolate reductase defects combined with no additional thrombophilic risk factors with venous thrombosis is less clear. High doses of folic acid to lower homocysteine levels might not be necessary.

Homocysteine levels are associated with increased risk of congestive heart failure in patients with and without coronary artery disease

BACKGROUND

Increased homocysteine (HCY) is associated with increased risk of vascular disease. Whether HCY affects development of congestive heart failure (CHF) independent of coronary artery disease (CAD) is uncertain. We evaluated whether increased HCY predicts low ejection fraction or clinical CHF.

METHODS

Patients (n = 2,842) undergoing coronary angiography had HCY measured between 1994 and 1999 and were prospectively studied. Left ventricular dysfunction (LVD) was defined as ejection fraction < or =40%. Multivariable regressions assessed predictive strength of HCY for LVD or LVD/CHF.

RESULTS

The average age was 64 +/- 12 years; 69% were men, and 74% had CAD. LVD was present in 12% and the combination of either LVD or clinical CHF was present in 21.9%. Quartiles of HCY were: < or =10.5 (Q1), 10.5-13.2 (Q2), 13.3-17.0 (Q3) and > or =17.1 micromol/l (Q4). LVD and LVD/CHF were more prevalent in Q3 (15, 25%) and Q4 (15, 27%) than in Q1 HCY (8.4, 18%; p < 0.001 vs. Q4). After adjustment, Q3 and Q4 HCY independently predicted LVD (OR = 1.7, 95% CI 1.2-2.5, p = 0.004; OR = 1.8, 95% CI 1.3-2.6, p = 0.002) or LVD/CHF (OR = 1.4, 95% CI 1.04-1.8, p = 0.03; OR = 1.7, 95% CI 1.3-2.2, p < 0.001). Findings did not differ by disease etiology: for Q4 among non-CAD patients, OR = 1.7 for LVD and OR = 1.7 for LVD/CHF. Further, there was no interaction of results with gender.

CONCLUSION

High HCY levels (Q3/4 > or =13.3 micromol/l) are associated with LVD and combined endpoint of LVD/clinical CHF. This relationship is independent of CHF etiology and gender. Further research is indicated to distinguish between a causal or noncausal mechanism for this association.

Homocysteine is not associated with arterial thickness and stiffness in healthy middle-aged French volunteers

BACKGROUND

To study the association between the total plasma homocysteine (tHcy) concentration and the carotid artery intima-medial wall thickness (IMT), pulse wave velocity (PWV) and the presence of arterial plaques in a French population.

METHODS

Cross-sectional analysis of data from 556 male and 559 female middle-aged participants (mean (+/-SD) age 59.6+/-4.7 years) provided by an ongoing intervention trial.

RESULTS

Mean geometric tHcy concentration was higher for men than for women (10.6 vs. 8.5 micromol/L, p<0.001) and was associated in the expected direction with known determinants. The mean IMT was 0.71+/-0.1 mm for men and 0.69+/-0.1 mm for women (p<0.001), the mean PWV was, respectively, 12.0+/-2.8 and 10.9+/-2.2 m/sec (p<0.001), and the percentages of subjects with plaques were, respectively, 40.8% and 22.7% (p<0.001). In men only, the age-adjusted mean IMT and PWV increased with an increasing tHcy concentration: the IMT was 0.71 mm in the first tHcy-quartile and 0.73 mm in the fourth tHcy-quartile (p for linear trend=0.03), the PWV values were, respectively, 11.6 and 12.4 m/sec (p for linear trend=0.01). These associations disappeared after adjustment for conventional cardiovascular disease risk factors.

CONCLUSION

In this population, the tHcy concentration was not associated with measures of arterial thickness and stiffness.

Is there a possible relation between atrophic gastritis and premature atherosclerosis?

BACKGROUND

In this study, we have aimed to show the possible relation between atrophic gastritis and premature atherosclerosis via hyperhomocysteinemia.

MATERIALS AND METHODS

Thirty-four patients with atrophic gastritis were enrolled to the study. The control group consisted of 35 patients with non-atrophic gastritis. Classical cardiovascular disease risk factors did not significantly differ between atrophic gastritis and control subjects. The presence and degree of atrophic gastritis were assessed histologically and Helicobacter pylori infection was determined by both histologic and serologic methods. Body mass index was measured by standard technique blood fasting glucose, serum creatinine, total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, vitamin B12, folic acid, and homocysteine levels were measured by biochemical methods. Carotid intima-media thickness was measured by B-mode ultrasonography to examine the premature atherosclerosis.

RESULTS

Plasma vitamin B12 levels were significantly lower (p = .00) and homocysteine levels were significantly higher (p = .01) in the atrophic gastritis group. There was no statistically significant difference in plasma folic acid levels between the two groups (p = .728). Carotid intima-media thickness was higher in the atrophic gastritis group than in the control group (0.516 mm versus 0.465 mm), but this difference did not show any statistical significance (p = .062).

CONCLUSION

Our results showed that atrophic gastritis may cause hyperhomocysteinemia, which is an independent risk factor for atherosclerosis and cardiovascular diseases. However, when compared with controls, carotid intima-media thickness of the atrophic gastritis patients was found to be higher but did not reach statistically significant levels.

Homocysteine, renal disease and cardiovascular disease in a remote Australian Aboriginal community

BACKGROUND

Rates of renal and cardiovascular disease are high among Aboriginal Australians living in remote communities. Nutritional problems, in particular low folate levels, are also common. This suggests that increased homocysteine concentrations might be widespread, and a possible contributor to the high rates of cardiovascular disease.

AIMS

To examine homocysteine concentrations, and their relationships to folate levels, and to markers of renal disease and cardiovascular disease in a remote Aboriginal Australian community

METHODS

As part of a cross-sectional survey among adults in one community, homocysteine concentrations, concentrations of the crucial determinants (red blood cell (RBC) folate, vitamin B(12) and the C677T methylene tetrahydrofolate reductase polymorphism) and cardiovascular risk factors were examined.

RESULTS

Among 221 people, geometric mean homocysteine concentration was 11.8 micromol/L (range: 11.1-12.5 micromol/L), with 57/221 (26%) values > or =15.0 micromol/L. Higher concentrations were associated with older age, male gender, lower RBC folate and lower vitamin B(12) concentrations and homozygosity for C677T. Homocysteine concentrations were not related to the presence of albuminuria, other than over the overt albuminuria range. Homocysteine concentrations were inversely correlated with calculated glomerular filtration rate (GFR). Carotid intima-media thickness, however, was not related to homocysteine concentration. In multivariate analyses, age, male gender, lower RBC folate concentrations, lower vitamin B(12) concentrations, lower calculated GFR and the C677T polymorphism were all associated with homocysteine concentrations.

CONCLUSIONS

Homocysteine concentrations were consistent with previous limited reports in Aboriginal communities. Although superficially they are similar to reports from non-Aboriginal settings, the younger age of this cohort and the association of homocysteine concentrations with age suggest that age-specific concentrations are higher among Aboriginal Australians. In addition to dietary determinants, the high prevalence of apparently reduced renal function renal disease appears to be an important determinant of homocysteine concentrations in remote Aboriginal communities. The role of homocysteine concentrations as a potential mediator of the high rates of cardiovascular disease remains to be determined.

Low concentrations of folate, not hyperhomocysteinemia, are associated with carotid intima-media thickness

AIM

We examined whether total homocysteine, B vitamins and the 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphism are related to common carotid intima-media thickness, a marker of atherosclerosis, and carotid distension, a marker of arterial stiffness.

METHODS

We used cross-sectional data from 819 individuals aged 50-70 years. B-mode ultrasound of the distal common carotid arteries was performed to determine maximum carotid intima-media thickness, mean carotid intima-media thickness and distension.

RESULTS

Carotid intima-media thickness and distension did not differ across homocysteine, serum folate, vitamin B(6) and vitamin B(12) quartiles or between MTHFR C677T genotype. Erythrocyte folate was independently associated with maximum carotid intima-media thickness (mean difference first versus third quartile, 0.03 mm, 95% CI 0.004-0.06 mm; first versus fourth quartile, 0.03 mm, 95% CI -0.002 to 0.06 mm). Further adjustment for homocysteine did not affect this association. Folate deficient subjects had greater maximum carotid intima-media thickness than those with high-normal folate concentrations (serum folate: mean difference 0.05 mm, 95% CI 0.01-0.08 mm; erythrocyte folate: mean difference 0.04 mm, 95% CI -0.03 to 0.11 mm).

CONCLUSION

Low folate concentrations, independent of hyperhomocysteinemia, may promote atherogenesis. Our findings confirm the null association of homocysteine with carotid intima-media thickness observed in other population-based studies, suggesting that hyperhomocysteinemia does not perpetuate atherosclerosis or arterial stiffness.

The effects of coffee consumption on lipid peroxidation and plasma total homocysteine concentrations: a clinical trial

Despite extensive research, the cardiovascular effects of coffee consumption in humans remain controversial. Our aim was to investigate the excretion of coffee phenols and the effects of filtered coffee consumption on oxidative stress and plasma homocysteine (tHcy) concentration in humans. The study consisted of a multiple-dose clinical supplementation trial and a single-dose study. In the long-term trial, 43 healthy nonsmoking men optionally consumed daily either no coffee, 3 cups (450 mL), or 6 cups (900 mL) of filtered coffee for 3 weeks, while in the short-term study 35 subjects consumed a single dose of 0, 1 (150 mL), or 2 cups (300 mL) of coffee. Long-term consumption of coffee increased the urinary excretion of caffeic and ferulic acid. The change in the total excretion of phenolic acids in 3 and 6 cups groups represented 3.8 and 2.5% of the amount ingested daily. Plasma tHcy concentrations increased nonsignificantly, but the consumption of coffee had neither short-nor long-term effects on lipid peroxidation or the activity of measured antioxidant enzymes. In conclusion, the consumption of filtered coffee does not have any detectable effects on lipid peroxidation in healthy nonsmoking men. The effect of coffee consumption on tHcy concentrations needs further investigation.

Homocysteine and carotid intima-media thickness: a critical appraisal of the evidence

This review examines the relationship between hyperhomocysteinemia, a risk factor for vascular disease, and carotid intima-media thickness (CIMT), a valid marker of generalized atherosclerosis and future vascular disease risk. The relationship between two important determinants of hyperhomocysteinemia in the general population-folate status and the 677C --> T methylenetetrahydrofolate reductase (MTHFR) polymorphism-and CIMT is also covered.

METHODS

We searched literature databases for articles examining homocysteine and CIMT published before September 2003.

RESULTS

We identified 54 studies. Observational studies generally failed to demonstrate a relationship between homocysteine and CIMT in homocystinuric, uremic, hypercholesterolemic or non-insulin-dependent diabetes mellitus patients or in subjects with insulin insensitivity. Weak associations, but usually only in certain sub-populations were found in vascular disease patients and in population-based studies. B vitamins reduce the progression of CIMT in renal transplant recipients and vascular disease patients as demonstrated by two trials. The majority of studies demonstrated increased CIMT in individuals with the MTHFR 677TT genotype. Folate status showed no relation to CIMT.

DISCUSSION

In non-patient populations, hyperhomocysteinemia is weakly associated with CIMT. The association of the 677 C--> T MTHFR polymorphism with CIMT further supports this finding. Lastly, folate levels may need to reach a critically low status before an association can be found between folate and CIMT. Larger trials in various population types are needed to determine whether folate alone or in combination with Vitamins B6 and B12 will slow down or even reverse atherosclerotic progression.

Homocysteine potentiates calcification of cultured rat aortic smooth muscle cells

Aortic calcification was demonstrated in experimental animal models of hyperhomocysteinemia. Mild hyperhomocysteinemia was associated with aortic calcification, suggesting a relationship between homocysteine (HCY) and the pathogenesis of aortic calcification. In the present study, the effect of HCY on vascular calcification was examined in calcifying and non-calcifying vascular smooth muscle cells (VSMCs). Cell calcification was induced by incubation of VSMCs with beta-glycerophosphate. Proliferation of VSMCs was studied by cell counting, 3H-thymidine (3H-TdR) and 3H-leucine (3H-Leu) incorporation. 45Ca accumulation, cell calcium content, and alkaline phosphatase (ALP) activity were measured as indices of calcification. The results showed that the proliferation of calcifying VSMCs, which was indicated by cell counting, 3H-TdR and 3H-Leu incorporation in calcifying VSMCs, was enhanced as compared with that of non-calcifying VSMCs. HCY promoted increases in cell number, 3H-TdR and 3H-Leu incorporation in both calcifying and non-calcifying VSMCs, but with more prominent effect in calcifying VSMCs. The stimulating effects of HCY on the three parameters in calcifying VSMCs were antagonized by PD98059, a specific inhibitor of mitogen activated protein kinase kinase (MAPKK). The ALP activity, 45Ca uptake, and calcium deposition in the calcifying VSMCs were greater than those in non-calcifying VSMCs. PD98059 had no effect on ALP activity, 45Ca uptake, and calcium deposition in calcifying VSMCs. HCY caused marked increases in 45Ca uptake and calcium deposition both in calcifying and non-calcifying VSMCs. HCY, however, enhanced ALP activity in the calcified VSMCs but not in the non-calcifying VSMCs. The non-calcifying VSMCs treated with HCY showed the same low ALP activity, as did the control VSMCs. In calcifying VSMCs, the HCY-induced increases in 45Ca uptake, calcium deposition, and ALP activity were also attenuated by PD98059. The results demonstrated that HCY potentiated VSMC calcification probably through the mechanisms by which HCY promotes atherosclerosis.

Vitamin supplementation reduces the progression of atherosclerosis in hyperhomocysteinemic renal-transplant recipients

BACKGROUND

We previously demonstrated among renal-transplant recipients (RTRs) a high prevalence of hyperhomocysteinemia, which might account for their elevated cardiovascular risk. The purpose of our study was to document, in hyperhomocysteinemic RTRs, the effect of vitamin supplementation on carotid intima-media thickness (cIMT), which is an early sign of atherosclerosis.

METHODS

A total of 56 stable hyperhomocysteinemic RTRs were randomly assigned to vitamin supplementation (folic acid 5 mg/day; vitamin B(6) 50 mg/day; vitamin B(12) 400 microg) (group A) or placebo treatment (group B) for 6 months. All subjects underwent cardiovascular risk-factor assessment, including fasting homocysteine (Hcy) levels assay, and high resolution B-mode ultrasound to measure the intima-media thickness of common carotid arteries, at time of enrollment and after 6 months.

RESULTS

Fasting Hcy levels markedly decreased in group A after treatment (21.8 [15.5-76.6] micromol/L vs. 9.3 [5.8-13] micromol/L; P<0.0001), whereas no significant changes were observed in group B (20.5 [17-37.6] micromol/L vs. 20.7 [15-34] micromol/L; P=not significant). In group A, cIMT significantly decreased after treatment (0.95+/-0.20 mm vs. 0.64+/-0.17 mm; P<0.0001). All except one patient showed a reduction of cIMT and the mean percentage of cIMT decrease was -32.2+/-12.9%. Patients with methylenetetrahydrofolate reductase (MTHFR) C677T +/+ genotype, with higher Hcy levels, had the major percentage of decrease of Hcy with respect to the other genotypes (mean decrease: MTHFR +/+ 74.8+/-5.7%; MTHFR +/- 58.1+/-10%; MTHFR -/- 56.3+/-8.6%). In hyperhomocysteinemic patients without vitamin supplementation (group B) we documented a significant increase in cIMT after 6 months (0.71+/-0.16 mm vs. 0.87+/-0.19 mm; P<0.05). In 19 of 28 subjects we observed an increase in cIMT, and in 9 of 28 the cIMT was unmodified. The mean percentage of cIMT increase was + 23.3+/-21.1%.

CONCLUSIONS

Our results demonstrate a beneficial effect of the treatment of hyperhomocysteinemia by vitamin supplementation on cIMT in a group of RTRs.

Anticardiolipin antibody titre and plasma homocysteine level independently predict intima media thickness of carotid arteries in subjects with idiopathic antiphospholipid antibodies

This study evaluated whether IgG anticardiolipin antibody (aCL) titre and traditional risk factors for atherosclerosis bore any relationship to the intima media thickness (IMT) of carotid arteries of patients with idiopathic antiphospholipid antibodies (aPL). IMT was assessed by high-resolution sonography at the common carotid, carotid bifurcation and internal carotid in 42 (13 male, 29 female, mean age 31+/-10 years) aPL subjects, 29 with primary thrombotic antiphospholipid syndrome and 13 with persistence of aPL in the absence of any underlying disorder. In the same subjects the following were measured: plasma fibrinogen (FNG), von Willebrand factor (vWF), plasminogen activator inhibitor (PAI), homocysteine (HC), total cholesterol (CHO), triglycerides (TG), high density and low density lipoprotein (HDL and LDL), platelet numbers and aCL of IgG and IgM isotype. IMT of the internal carotid was greater in males than females (0.48+/-0.03 vs 0.39+/-0.01 mm, P=0.02). IMT of the carotid bifurcation was greater in thrombotic than nonthrombotic subjects (0.50+/-0.02 vs 0.42+/-0.02 mm, P=0.04). By simple regression, IMT of the common carotids correlated with age (P< 0.0001) IgG aCL titre (P=0.001), FNG (P=0.006), LDL (0.01), CHO (0.02) and PAI (P=0.02). IMT of the carotid bifurcation correlated with age (P=0.002), IgG aCL titre (P=0.0002), FNG (P=0.0001), HC (P=0.009), CHO (P=0.02), vWF (P=0.01) and number of thrombotic events (P=0.03). IMT of the internal carotids correlated with age (P=0.002), IgG aCL titre (P=0.0001), FNG (P=0.0008), PAI (P=0.002) and HC (P=0.01). By stepwise multiple regression analysis, IgG aCL titre independently predicted IMT at all carotid segments examined (P always <0.005). In addition, plasma FNG and HC also resulted independent predictors of IMT at the carotid bifurcation (P=0.001 and P<0.0001, respectively) and internal carotid (P=0.03 and P<0.0001, respectively). These data strongly support an atherogenic role for IgG aCL in patients with aPL. Measurement of plasma HC and FNG may help define aPL subjects at higher vascular risk who may require lowering of HC and FNG by vitamin and/or pharmacologic intervention.

Homocysteine is the only plasma thiol associated with carotid artery remodeling

Several authors have reported that moderate hyperhomocysteinemia is related to asymptomatic carotid arterial wall remodeling, but few data are available on other thiol compounds with potential vascular toxicity. We, therefore, investigated the relationships between major plasma thiol compounds (homocysteine, cysteine and glutathione) and the structural phenotype of the common carotid artery in a cohort of 123 subjects with no evidence of cardiovascular disease. Fasting levels of thiol compounds were measured by high-performance liquid chromatography, and arterial geometry was evaluated using high-resolution echotracking devices. In univariate regression analysis, plasma homocysteine and plasma cysteine concentrations were positively associated with carotid artery internal diameter (P=0.0001 and 0.002, respectively) and intima media thickness (P=0.003 and 0.004), but the plasma glutathione concentration was not. In multivariate analysis, plasma homocysteine was independently and positively associated with carotid artery internal diameter (P<0.005) and intima media thickness (P<0.05), but plasma cysteine was not. These data suggest that homocysteine is the only plasma thiol compound that may be considered as a risk factor for preclinical cardiovascular disease.

Homocysteine and cardiovascular disease: current evidence and future prospects

Hyperhomocysteinemia is an independent risk factor for cardiovascular disease. Despite the well-known effectiveness of vitamin supplementation in reducing homocysteine levels, it is not known whether lowering of homocysteine levels is associated with a reduction in cardiovascular morbidity and mortality. The aim of this review is to discuss the epidemiologic evidence about the relation between homocysteine and cardiovascular disease, the pathophysiologic mechanisms responsible for the deleterious vascular and hemostatic effects of homocysteine, and studies of the potential benefits of homocysteine-lowering therapy.

Nutriceuticals and cardiovascular health in women

This article examines the evidence on use of nutriceuticals for promotion of cardiovascular health in women. Studies elucidating mechanism of action, physiologic effects of antioxidant vitamins, carotenoids, flavonoids, and garlic are presented. Emerging evidence for the impact of homocysteine on cardiovascular risk factors and events and evidence for the impact of different types of fats on cardiovascular markers are reviewed. The effects of a heart-healthy diet are supported in this review of research on nutriceuticals. Primary prevention of cardiovascular disease in women is clearly efficacious, and this article summarizes information to be shared with women about nutriceuticals and diet to better enable decisions they can adopt to promote cardiovascular health.

APOC3, CETP, fibrinogen, and MTHFR are genetic determinants of carotid intima-media thickness in healthy men (the Stanislas Cohort)

The purpose of this study was to examine the relationship between carotid intima-media thickness (CIMT) inter-individual variability and 16 polymorphisms of 11 genes associated with cardiovascular risk factors (genes among lipid and homocysteine metabolisms, blood viscosity, platelet aggregation, leukocyte adhesion and renin-angiotensin system). CIMT was measured by high resolution B-mode ultrasonography in an healthy population of 77 men and 84 women, aged 35-54 years and selected from a French Cohort: the Stanislas Cohort. The polymorphisms studied were genotyped by a multilocus approach. Statistical analyses were carried out by ANOVA, after adjustment of CIMT for age, body mass index, and smoking, and by multiple regression analyses. No association was found with APOB Thr71Ile, APOC3 -482C/T, -455T/C, GpIIIa P1A, AT1R 1166A/C, AGT Met235Thr, CBS Ile278Thr, SELE 98G/T, and SELE Ser128Arg, polymorphisms neither in men nor in women. Although, in women we did not find any association for APOC3 3206T/G, 3175C/G, 1100C/T, CETP Ile405Val, MTHFR 677C/T and fibrinogen -455G/A polymorphisms; in men these polymorphisms were associated with CIMT variability (p< or =0.01; p< or =0.05). The most interesting finding was that altogether these genes in men were able to explain a considerable part, 20.6%, of CIMT variability. Therefore, our study gives a new opportunity to understand CIMT variability.

Increasing levels of dietary homocystine with carotid endarterectomy produced proportionate increases in plasma homocysteine and intimal hyperplasia

PURPOSE

The role that homocysteine may play in post-carotid endarterectomy (CEA) restenosis due to intimal hyperplasia is not well understood. This study was designed to investigate the effects of different levels of dietary homocystine on: (1) plasma homocysteine; (2) post-CEA intimal hyperplasia; and (3) levels of the methyl donor S-adenosylmethionine (SAM) and its counterpart S-adenosylhomocysteine (SAH) in the homocysteine pathway.

METHODS

Male rats were fed specialized diets for 2 weeks pre- and post-CEA. Groups included control (0 homocystine added, n=9), 1.5 (1.5 g/kg homocystine added, n=10), 3.0 (3.0 g/kg homocystine added, n=9), and 4.5 (4.5 g/kg homocystine added, n=11). The rats underwent a surgical carotid endarterectomy. Endpoints included; plasma homocysteine, intimal hyperplasia, replicative index using with alpha-SM actin and BrdU, hepatic SAM levels, SAH levels, and the hepatic activities of methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS).

RESULTS

Increasing dietary homocystine produced a proportionate increase in plasma homocysteine and an increase in intimal hyperplasia. Regression analysis of plasma homocysteine levels and intimal hyperplasia showed a significant correlation (r=0.71,P=0.003). Plasma homocysteine levels above 15 microM were associated with significant increases in intimal hyperplasia above 6.5% (P=0.04). Elevation of plasma homocysteine levels to moderate levels (5-25 microM) resulted in significant post-CEA intimal hyperplasia. Cellular analysis of the area of intimal hyperplasia in all diet groups showed comparable amounts of cells positive for alpha-SM actin. However, with increasing levels of dietary homocystine and plasma homocysteine there was an increase in replicative index (P<0.001) as determined by BrdU staining. Increasing dietary homocystine increased plasma homocysteine and was followed by increases in the replicative index thus producing increased intimal hyperplasia and lumenal stenosis. In hepatic measurements the 1.5 and 3.0 g/kg homocystine diets caused: increased liver activity of MTHFR (P=0.03) and decreased hepatic levels of SAM, SAH and SAM/SAH ratios compared to controls. Homocystine treatment did not cause significant alterations in CBS levels (P=0.992). These studies also showed no correlation of the MTHFR and CBS enzymes with plasma homocysteine levels or intimal hyperplasia. However, hepatic levels of SAM showed significant negative correlations with plasma homocysteine (r=-0.58; P=0.006) and with BrdU percentages of cellular proliferation (r=-0.69; P=0.06).

CONCLUSION

The degree of post-CEA intimal hyperplasia in a rat model is directly related to the plasma level of homocysteine. The hyperplastic effects of homocysteine may be mediated in part by a physiological insufficiency of methyl donors as shown by decreases in SAM. Thus, increasing levels of plasma homocysteine enhanced and accelerated the smooth muscle cell response after CEA which led to increased intimal hyperplasia and lumenal stenosis.

Serum homocysteine does not associate with uncomplicated coronary heart disease

BACKGROUND

Elevated serum homocysteine concentrations have been related to coronary heart disease. However, the association has not indisputably been proven, and the mechanisms by which homocysteine may be atherogenic have only partially been elucidated. The objective of the present study was to investigate whether serum homocysteine is associated with angina pectoris and myocardial infarction.

METHODS

We compared serum homocysteine concentrations in subjects with clinical evidence of angina pectoris or history of myocardial infarction to age-matched controls. The study included 248 males, who participated in a large cross-sectional risk factor survey carried out in five geographic areas in Finland.

RESULTS

Serum homocysteine concentration was significantly higher in subjects with a history of myocardial infarction compared to controls (15.3 micromol L-1 and 13.9 micromol L-1 respectively, P = 0.037). In a logistic regression model including several cardiovascular risk factors, serum homocysteine was significantly associated with myocardial infarction (95% CI 1.0157-1.2990, P = 0.027). Serum homocysteine concentrations did not differ between subjects with angina pectoris and age-matched controls (13.9 micromol L-1 and 14.2 micromol L-1 respectively).

CONCLUSIONS

Our results suggest that elevated serum homocysteine is associated with myocardial infarction but not with uncomplicated coronary heart disease.

Homocysteine and ischaemic stroke in men: the Caerphilly study

OBJECTIVE

To assess the risk of ischaemic stroke associated with total serum homocyst(e)ine (tHcy) concentration.

DESIGN

Cohort study.

SETTING

Caerphilly, South Wales

PARTICIPANTS

2254 men age 50 to 64 years recruited between 1984 and 1988.

RESULTS

107 men developed ischaemic stroke and mean follow up time was 10.2 years. There was no significant difference in mean serum total homocyst(e)ine levels between stroke cases (12.2 micromol 95% CI 11.6 to 13.1) and non-cases (11.7 micromol 95% CI 11.5 to 11.9) (p=0.14). There was no significant risk for a standard deviation increase in homocyst(e)ine (adjusted hazard ratio = 1.1, 95% CI 0.9 to 1.4). An interaction was observed between homocyst(e)ine and age at entry (p=0.003). The adjusted odds ratio comparing the top quintile of homocyst(e)ine with the rest was 2.5 (95% CI 1.0 to 6.2) for strokes occurring under 65 years and 0.5 (95% CI 0.2 to 1.3) at 65 years or older (p value for interaction =0.02). Risk also differed by blood pressure status. The adjusted hazard ratio for a standard deviation increase in homocyst(e)ine was 0.8, (95% CI 0.6 to 1.2) for normotensive men and 1.3 (95% CI 1.1 to 1.7) for hypertensive men (p value for interaction =0.01).

CONCLUSIONS

Overall, there is no significant relation between homocyst(e)ine and ischaemic stroke in this cohort. However, its aetiological importance may be greater for premature ischaemic strokes (<65 years) and in hypertensive men.

Low plasma lycopene concentration is associated with increased intima-media thickness of the carotid artery wall

Although a number of epidemiological studies have evaluated the association between ss-carotene and the risk of cardiovascular diseases, there has been little research on the role of lycopene, an acyclic form of ss-carotene, with regard to the risk of cardiovascular disease. We investigated the relationship between plasma concentrations of lycopene and intima-media thickness of the common carotid artery wall (CCA-IMT) in 520 middle-aged men and women (aged 45 to 69 years) in eastern Finland. They were examined from 1994 to 1995 at the baseline of the Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) study, a randomized trial concerning the effect of vitamin E and C supplementation on atherosclerotic progression. The subjects were classified into 2 categories according to the median concentration of plasma lycopene (0.12 micromol/L in men and 0.15 micromol/L in women). Mean CCA-IMT of the right and left common carotid arteries was 1.18 mm in men and 0.95 mm in women with plasma lycopene levels lower than the median and 0.97 mm in men (P:<0.001 for difference) and 0.89 mm in women (P:=0.027 for difference) with higher levels of plasma lycopene. In ANCOVA adjusting for cardiovascular risk factors and intake of nutrients, in men, low levels of plasma lycopene were associated with a 17.8% increment in CCA-IMT (P:=0.003 for difference). In women, the difference did not remain significant after the adjustments. We conclude that low plasma lycopene concentrations are associated with early atherosclerosis, manifested as increased CCA-IMT, in middle-aged men living in eastern Finland.

Plasma total homocysteine concentration and the risk of acute coronary events: the Kuopio Ischaemic Heart Disease Risk Factor Study

OBJECTIVES

Results from prospective studies concerning the association between plasma total homocysteine (tHcy) concentration and coronary heart disease (CHD) are conflicting. The purpose of this study was to test the hypothesis that plasma tHcy is associated with an increased risk of acute coronary events in middle-aged men.

DESIGN AND SUBJECTS

We investigated this association in a prospective nested case-control study among Eastern Finnish men aged 42-60 years. Plasma tHcy measurements were carried out for 163 men who had an acute coronary event during an average 8 years and 11 months follow-up of the whole cohort and for 163 control subjects. Both the cases and the controls were from a cohort of 2005 men who had no clinical CHD at the Kuopio Ischaemic Heart Disease (KIHD) baseline.

RESULTS

Men in the highest plasma tHcy concentration quarter had no increase in the risk of coronary events compared with men with lower tHcy concentrations (odds ratio = 0.88, 95% confidence interval 0.44-1.76). Average follow-up time before the first coronary event was 4.9 years (SD 3.2) in men in the highest plasma tHcy quarter and 5.5 years (SD 3.1) in men in the three lowest quarters (P = 0.368).

CONCLUSION

We conclude that plasma tHcy is not associated with an increased risk of coronary events in the middle-aged male population in eastern Finland.

Plasma homocysteine and its association with carotid intimal-medial wall thickness and prevalent coronary heart disease: NHLBI Family Heart Study

Mildly elevated plasma total homocysteine (tHcy) levels have been associated with increased risk of coronary heart disease (CHD). Carotid artery intimal-medial wall thickening is a predictor of cardiovascular disease and has been previously shown to be positively associated with plasma tHcy in studies of asymptomatic subjects. In the current study we examined 1467 subjects with regard to their fasting plasma tHcy levels and intimal-medial wall thickness as measured by B-mode ultrasound and early onset CHD. The results showed that there is a significant positive association between plasma tHcy levels and carotid-artery wall thickness in participants 55 years or older even after the tHcy levels are adjusted for age, smoking and anti-hypertensive medication. The direction and magnitude of the relationship is similar although the result was not statistically significant in younger participants ( < 55 years). Early onset CHD at any age was not significantly different across the tHcy quintiles. The lack of an association of tHcy and CHD in the presence of a positive association with intimal-medial wall thickening may be a reflection of increased statistical power of quantitative versus qualitative traits. We conclude that the present finding of a positive association between tHcy and intimal-medial wall thickness strengthens the in vitro finding of the stimulating effect of homocysteine on vascular smooth muscle cell growth. Vascular smooth muscle cell proliferation may be an important mechanism through which mildly elevated plasma tHcy promotes atherosclerosis.

The controversy over homocysteine and cardiovascular risk

Elevated plasma total homocysteine (tHcy) is a risk factor for occlusive cardiovascular disease (CVD). This concept is based on the observations of premature vascular disease in patients with homocystinuria, the relation between tHcy and both clinical CVD as well as preclinical atherosclerotic disease, the relation between tHcy in children and CVD in their parents or relatives, and reduction in CVD or surrogate endpoints after tHcy-lowering intervention with B vitamins. Plausible mechanisms include the in vivo interference with nitric oxide-dependent reactive vasodilatation. Some observations have raised questions about tHcy as a risk factor. 1) Some prospective studies showed a weak relation or no relation between tHcy and CVD. 2) Several traditional risk factors are associated with tHcy and may confound the relation between tHcy and CVD. 3) tHcy is related to renal function, and hyperhomocysteinemia may reflect early nephrosclerosis. 4) The C677T transition of the methylenetetrahydrofolate reductase gene causes a moderate increase in tHcy but no or only minor increased CVD risk. However, the strength of some of these arguments can be questioned because there is increasing evidence that tHcy is a proximate risk factor provoking the acute event, it strongly interacts with traditional risk factors, and it may predict CVD or death in patients with chronic renal failure. Furthermore, the studies of the C677T polymorphism lack statistical power, and the TT genotype may even modulate CVD risk independently of homocysteine. Thus, only placebo-controlled intervention studies with tHcy-lowering B vitamins and clinical endpoints can provide additional valid arguments for the debate over whether tHcy is a causal CVD risk factor.

Nutritional aspects and possible pathological mechanisms of hyperhomocysteinaemia: an independent risk factor for vascular disease

Numerous case-control and prospective studies have identified elevated plasma homocysteine as a strong independent risk factor for cerebovascular, cardiovascular and peripheral vascular disease. Homocysteine is formed as a result of the breakdown of the dietary amino acid methionine. Once formed, homocysteine is either remethylated to methionine, or undergoes a trans-sulfuration reaction to form cysteine. The re-methylation of homocysteine to methionine is dependent on three B-vitamins, i.e. riboflavin, vitamin B12 and folate. The second pathway of homocysteine metabolism is the trans-sulfuration pathway which requires both vitamin B6 and riboflavin for its activity. Thus, up to four B-vitamins are required for intracellular homocysteine metabolism. Many studies have noted strong inverse relationships between homocysteine levels and the status of both vitamin B12 and folate. However, the relationship between vitamin B6 status and homocysteine is still uncertain. Similarly, numerous intervention studies have demonstrated effective lowering of homocysteine levels as a result of folate and vitamin B12 supplementation, while the homocysteine-lowering ability of vitamin B6 is unclear. Even though riboflavin plays a crucial role in both the trans-sulfuration and remethylation pathways of homocysteine metabolism, the relationship between riboflavin status and homocysteine levels has not been investigated. The exact mechanism that explains the vascular toxicity of elevated homocysteine levels is unknown at present, studies indicate that it is both atherogenic and thrombogenic. To date, no randomized clinical trial has demonstrated that lowering of homocysteine levels is beneficial in terms of reducing the prevalence of vascular disease. It is probable, however, that optimal B-vitamin status is important in the prevention of vascular disease.

Carotid intima-media thickness as a measure of vascular target organ damage

This paper summarizes important investigations published within the past 2 years that use B-mode carotid ultrasound and measurements of intima-media thickness or plaque to elucidate the relationship between traditional or novel risk factors for the development of atherosclerotic or arteriosclerotic disease. This methodology is proposed as an extremely useful, noninvasive tool with proven ability to show cross-sectional associations with cardiovascular risk factors, prevalence of vascular disease, and predictive power. The method appears highly suited to the goal of detecting asymptomatic vascular target organ damage, which may greatly assist with assessment of risk and selection of appropriate, preventive, strategies for management of disease.

Total homocysteine and cardiovascular disease

Recent data have shown that an elevated plasma level of the amino acid homocysteine (Hcy) is a common, independent, easily modifiable and possibly causal risk factor for cardiovascular disease (CVD) which may be of equal importance to hypercholesterolemia, hypertension and smoking. This paper reviews the biochemical, clinical, epidemiological and experimental data underlying this conclusion and is critically questioning whether elevated tHcy is a causal factor.

Serum homocysteine, MTHFR gene polymorphism, and carotid intimal-medial thickness in NIDDM subjects

We assessed the contribution of serum homocysteine levels, an independent risk factor for vascular disease, and of the methylenetetrahydrofolate reductase (MTHFR) C677T mutation to the variability of carotid intimal-medial thickness (IMT) in patients with non-insulin-dependent diabetes mellitus (NIDDM). Ninety-five patients (33 males and 62 females, mean age 53 +/- 10 years) without nephropathy or other vascular complications were enrolled. Fasting total serum homocysteine and other biochemical analytes were measured. The MTHFR polymorphism was determined by the polymerase chain reaction. Common carotid IMT and plaques or stenoses in the carotid district were measured by ultrasonography. Serum total homocysteine concentrations were higher in subjects with the mutant (Val/Val) genotype than in those with the Ala/Val plus Ala/Ala genotypes (P = 0.02). On univariate analysis, carotid IMT was significantly associated with age, body mass index (BMI), systolic blood pressure, and total cholesterolemia. No significant association was found between IMT and serum homocysteine or the MTHFR polymorphism, although a slightly greater IMT was observed in the homozygous Val genotypes. On multiple regression analysis, only age and BMI were independently associated with IMT and explained about 40% of IMT variability. The results did not change when the analysis was restricted to the subgroups with or without atherosclerotic plaques in the carotid district. In 95 Italian NIDDM patients without nephropathy, neither basal levels of serum total homocysteine nor the MTHFR C677T polymorphism predicted significant changes in common carotid intimal-medial thickness.

Homocysteine as a novel risk factor for atherosclerosis

Homocysteine is a sulfhydryl amino acid formed during metabolism of methionine. Increasing evidence suggests that homocyst(e)ine may act as an independent risk factor for ischemic heart disease, cerebrovascular disease, and peripheral arterial disease. Recent prospective data have shown that homocyst(e)ine levels in the top 20% of the population increase the risk for ischemic heart disease by approximately twofold. Homocyst(e)ine seems to promote the progression of atherosclerosis by causing endothelial dysfunction, increasing oxidant stress, and promoting vascular smooth muscle growth. Recent human studies using methionine loading to experimentally induce moderate hyperhomocyst(e)inemia have demonstrated rapid and profound impairment of resistance and conduit artery endothelial function. No data are available from randomized, controlled trials of the effects of lowering plasma homocyst(e)ine on atherosclerotic vascular events; however, screening for hyperhomocyst(e)inemia should be actively considered in individuals with progressive and unexplained atherosclerosis. Both fasting and postmethionine load homocyst(e)ine levels should be measured. B vitamins, including folic acid and vitamins B6 and B12 are the mainstay of treatment of patients with hyperhomocyst(e)inemia. Primary prevention strategies await the completion of long-term, randomized, prospective studies.