What level of plasma homocyst(e)ine should be treated? Effects of vitamin therapy on progression of carotid atherosclerosis in patients with homocyst(e)ine levels above and below 14 micromol/L

Lactobacillus Eats Amyloid Plaque and Post-Biotically Attenuates Senescence Due to Repeat Expansion Disorder and Alzheimer's Disease

Patients with Alzheimer's disease and related dementia (ADRD) are faced with a formidable challenge of focal amyloid deposits and cerebral amyloid angiopathy (CAA). The treatment of amyloid deposits in ADRD by targeting only oxidative stress, inflammation and hyperlipidemia has not yielded significant positive clinical outcomes. The chronic high-fat diet (HFD), or gut dysbiosis, is one of the major contributors of ADRD in part by disrupted transport, epigenetic DNMT1 and the folate 1-carbon metabolism (FOCM) cycle, i.e., rhythmic methylation/de-methylation on DNA, an active part of epigenetic memory during genes turning off and on by the gene writer (DNMT1) and eraser (TET2/FTO) and the transsulfuration pathway by mitochondrial 3-mercaptopyruvate sulfur transferase (3MST)-producing H2S. The repeat CAG expansion and m6A disorder causes senescence and AD. We aim to target the paradigm-shift pathway of the gut-brain microbiome axis that selectively inhibits amyloid deposits and increases mitochondrial transsulfuration and H2S. We have observed an increase in DNMT1 and decreased FTO levels in the cortex of the brain of AD mice. Interestingly, we also observed that probiotic lactobacillus-producing post-biotic folate and lactone/ketone effectively prevented FOCM-associated gut dysbiosis and amyloid deposits. The s-adenosine-methionine (SAM) transporter (SLC25A) was increased by hyperhomocysteinemia (HHcy). Thus, we hypothesize that chronic gut dysbiosis induces SLC25A, the gene writer, and HHcy, and decreases the gene eraser, leading to a decrease in SLC7A and mitochondrial transsulfuration H2S production and bioenergetics. Lactobacillus engulfs lipids/cholesterol and a tri-directional post-biotic, folic acid (an antioxidant and inhibitor of beta amyloid deposits; reduces Hcy levels), and the lactate ketone body (fuel for mitochondria) producer increases SLC7A and H2S (an antioxidant, potent vasodilator and neurotransmitter gas) production and inhibits amyloid deposits. Therefore, it is important to discuss whether lactobacillus downregulates SLC25A and DNMT1 and upregulates TET2/FTO, inhibiting β-amyloid deposits by lowering homocysteine. It is also important to discuss whether lactobacillus upregulates SLC7A and inhibits β-amyloid deposits by increasing the mitochondrial transsulfuration of H2S production.

Analysis of Plasma Homocysteine Levels in Patients with Chronic Periodontitis Before and After Nonsurgical Periodontal Therapy Using High-Performance Liquid Chromatography

INTRODUCTION

Homocysteine (Hcy), an inflammatory biomarker, is a sulfur-containing amino acid. Elevated levels of plasma Hcy are evident in various inflammatory conditions and have been described as an independent risk factor for cardiovascular disease. The literature has also stated that a similar association could exist between the chronic periodontitis and plasma-Hcy levels, in otherwise systemically healthy individuals. However, studies on Hcy levels in periodontitis are scarce. Hence, this study aimed to assess the levels of plasma Hcy in patients with chronic periodontitis before and after nonsurgical periodontal therapy.

MATERIALS AND METHODS

This longitudinal, case-control clinical study included a total of 60 patients who were divided into two groups. Periodontal parameters including Plaque Index, Gingival Index, Sulcus Bleeding Index, probing depth, and clinical attachment level were recorded at baseline and 12 weeks after periodontal therapy. A high-performance liquid chromatography analysis was performed to measure the Hcy levels. The results were evaluated statistically for intergroup pair-wise comparisons by Mann-Whitney U-test and intragroup comparison by Wilcoxon-matched pairs test. Correlation between the plasma-Hcy levels with other clinical parameters in all groups was done by Spearman's rank correlation method.

RESULTS

The Hcy was detectable in all the samples. At baseline, the mean levels of plasma Hcy were found to be low in the control group, whereas in the test group, it is found to be higher. These plasma-Hcy levels and all periodontal parameters were reduced significantly after nonsurgical periodontal therapy.

CONCLUSION

The results demonstrated that plasma-Hcy levels are reduced after nonsurgical periodontal therapy but not to the levels comparable with those found in healthy individuals. Therefore, nonsurgical periodontal therapy may be used as an adjunctive Hcy-lowering therapy, contributing toward primary prevention against cardiovascular diseases.

Sensitive three-dimensional ultrasound assessment of carotid atherosclerosis by weighted average of local vessel wall and plaque thickness change

PURPOSE

Vitamin B deficiency has been identified as a risk factor for vascular events. However, the reduction of vascular events was not shown in large randomized controlled trials evaluating B-Vitamin therapy. There is an important requirement to develop sensitive biomarkers to be used as efficacy targets for B-Vitamin therapy as well as other dietary treatments and lifestyle regimes that are being developed. Carotid vessel-wall-plus-plaque thickness change (VWT-Change) measured from 3D ultrasound has been shown to be sensitive to atorvastatin therapies in previous studies. However, B-Vitamin treatment is expected to confer a smaller beneficial effect in carotid atherosclerosis than the strong dose of atorvastatin. This paper introduces a sensitive atherosclerosis biomarker based on the weighted mean VWT-Change measurement from 3D ultrasound with a purpose to detect statistically significant effect of B-Vitamin therapy.

METHODS

Of the 56 subjects analyzed in this study, 27 were randomized to receive a B-Vitamin tablet daily and 29 received a placebo tablet daily. Participants were scanned at baseline and 1.9 ± 0.8 yr later. The 3D VWT map at each scanning session was computed by matching the outer wall and lumen surfaces on a point-by-point basis. The 3D annual VWT-Change maps were obtained by first registering the 3D VWT maps obtained at the baseline and follow-up scanning sessions, and then taking the point-wise difference in VWT and dividing the result by the years elapsed from the baseline to the follow-up scanning session. The 3D VWT-Change maps constructed for all patients were mapped to a 2D carotid template to adjust for the anatomic variability of the arteries. A weight at each point of the carotid template was assigned based on the degree of correlation between the VWT-Change measurements exhibited at that point and the treatment received (i.e., B-Vitamin or placebo) quantified by mutual information. The weighted mean of VWT-Change for each patient, denoted by ΔVWT¯Weighted, was computed according to this weight. T-tests were performed to compare the sensitivity of ΔVWT¯Weighted with existing biomarkers in detecting treatment effects. These biomarkers included changes in intima-media thickness (IMT), total plaque area (TPA), vessel wall volume (VWV), unweighted average of VWT-Change (ΔVWT¯) and a previously described biomarker, denoted by ΔVWT¯S, that quantifies the mean VWT-Change specific to regions of interest identified by a feature selection algorithm.

RESULTS

Among the six biomarkers evaluated, the effect of B Vitamins was detected only by ΔVWT¯Weighted in this cohort (P=4.4×10-3). The sample sizes per treatment group required to detect an effect as large as exhibited in this study were 139, 178, 41 for ΔVWV, ΔVWT¯ and ΔVWT¯Weighted respectively.

CONCLUSION

The proposed weighted mean of VWT-Change is more sensitive than existing biomarkers in detecting treatment effects. This measurement tool will allow for many proof-of-principal studies to be performed for various novel treatments before a more costly study involving a larger population is held to validate the results.

Concise biomarker for spatial-temporal change in three-dimensional ultrasound measurement of carotid vessel wall and plaque thickness based on a graph-based random walk framework: Towards sensitive evaluation of response to therapy

Rapid progression in total plaque area and volume measured from ultrasound images has been shown to be associated with an elevated risk of cardiovascular events. Since atherosclerosis is focal and predominantly occurring at the bifurcation, biomarkers that are able to quantify the spatial distribution of vessel-wall-plus-plaque thickness (VWT) change may allow for more sensitive detection of treatment effect. The goal of this paper is to develop simple and sensitive biomarkers to quantify the responsiveness to therapies based on the spatial distribution of VWT-Change on the entire 2D carotid standardized map previously described. Point-wise VWT-Changes computed for each patient were reordered lexicographically to a high-dimensional data node in a graph. A graph-based random walk framework was applied with the novel Weighted Cosine (WCos) similarity function introduced, which was tailored for quantification of responsiveness to therapy. The converging probability of each data node to the VWT regression template in the random walk process served as a scalar descriptor for VWT responsiveness to treatment. The WCos-based biomarker was 14 times more sensitive than the mean VWT-Change in discriminating responsive and unresponsive subjects based on the p-values obtained in T-tests. The proposed framework was extended to quantify where VWT-Change occurred by including multiple VWT-Change distribution templates representing focal changes at different regions. Experimental results show that the framework was effective in classifying carotid arteries with focal VWT-Change at different locations and may facilitate future investigations to correlate risk of cardiovascular events with the location where focal VWT-Change occurs.

Design and statistical issues in the homocysteinemia in kidney and end stage renal disease (HOST) study

The Homocysteine Study (HOST) Veterans Affairs Cooperative Studies Program No. 453, is a prospective, randomized, two arm, double blind study of patients with end stage renal disease (ESRD) or advanced chronic kidney disease (ACKD, defined as an estimated creatinine clearance of 30 ml/min or less). Its primary objective is to determine whether administration of high doses of three vitamins, folic acid, vitamin B6 and vitamin B12, to lower the high plasma homocysteine levels, will reduce all cause mortality. The secondary objectives are to examine whether the treatment lowers the incidence of myocardial infarction, stroke, amputation of a lower extremity, a composite of death and the foregoing three events, the plasma homocysteine level, and, in ESRD patients undergoing hemodialysis, thrombosis of the vascular access. A unique feature of this trial is that after initial evaluation at enrollment and one return visit the follow up is exclusively by phone (or, if necessary, by mail). The subject is contacted every three months throughout the duration of the study from a central location. The study drug is shipped to the patient from a central location rather supplied locally. In a two year enrollment period, 2006 patients are to be enrolled. The duration of the observation period is four to six years. Data will be stored and analyzed at a coordinating center. The study design has the power to detect a reduction in all cause mortality rate of 17%. Issues related to the unique features of the design of this study are discussed.

Hyperhomocysteinemic Diabetic Cardiomyopathy: Oxidative Stress, Remodeling, and Endothelial-Myocyte Uncoupling

Accumulation of oxidized-matrix (fibrosis) between the endothelium (the endothelial cells embedded among the myocytes) and cardiomyocytes is a hallmark of diabetes mellitus and causes diastolic impairment. In diabetes mellitus, elevated levels of homocysteine activate matrix metalloproteinase and disconnect the endothelium from myocytes. Extracellular matrix functionally links the endothelium to the cardiomyocyte and is important for their synchronization. However, in diabetes mellitus, a disconnection is caused by activated metalloproteinase, with subsequent accumulation of oxidized matrix between the endothelium and myocyte. This contributes to endothelial-myocyte uncoupling and leads to impaired diastolic relaxation of the heart in diabetes mellitus. Elevated levels of homocysteine in diabetes are attributed to impaired homocysteine metabolism by glucose and insulin and decreased renal clearance. Homocysteine induces oxidative stress and is inversely related to the expression of peroxisome proliferators activated receptor (PPAR). Several lines of evidence suggest that ablation of the matrix metalloproteinase (MMP-9) gene ameliorates the endothelial-myocyte uncoupling in diabetes mellitus. Homocysteine competes for, and decreases the PPARγ activity. In diabetes mellitus, endothelial-myocyte uncoupling is associated with matrix metalloproteinase activation and decreased PPARγ activity. The purpose of this review is to discuss the role of endothelial-myocyte uncoupling in diabetes mellitus and increased levels of homocysteine, causing activation of latent metalloproteinases, decreased levels of thioredoxin and peroxiredoxin, and cardiac tissue inhibitor of metalloproteinase (CIMP) in response to antagonizing PPARγ.

Myriad Cardiac Manifestation of Hyperhomocysteinemia

Homocysteine has been recognized as a risk factor for various cardiovascular manifestations including thrombosis of arterial and venous system, spontaneous dissection involving various vessels in the body including coronaries and aneurysms. Here we report a young gentleman who was diagnosed as stroke in young and found to have dilated cardiomyopathy, with left ventricular dysfunction and hyperhomocysteinemia. Now the patient was presenting with unstable angina and found to have layered left ventricular thrombus on echocardiography and spontaneous coronary artery dissection on angiography. Our patient is being followed up on optimal medical management, as he is asymptomatic with medications.

Effect of non-surgical periodontal therapy on plasma homocysteine levels in Indian population with chronic periodontitis: a pilot study

AIM

Homocysteine (Hcy) is implicated in the development of cardiovascular diseases (CVD). The effect of periodontal disease and periodontal therapy on plasma Hcy remains controversial. Hence, in this pilot study we assessed the effect of periodontal disease and non-surgical periodontal therapy (NSPT) on plasma Hcy in systemically healthy Indian subjects.

MATERIALS AND METHODS

Forty participants (30 to 39 years) were enrolled in the study and were divided into two groups based on gingival index, probing depth, and clinical attachment level (CAL): Healthy (control group; n = 20) and Chronic Periodontitis (test group; n = 20). Plasma samples were collected and quantified at baseline and 12 weeks after scaling and root planing (SRP) for Hcy using High Performance Liquid Chromatography with fluorescent detection (HPLC-fld).

RESULTS

Plasma Hcy levels of chronic periodontitis (17.87 ± 1.21 μmol/l) subjects was significantly higher than healthy subjects (9.09 ± 2.11 μmol/l). Post-therapy, the plasma Hcy concentration reduced significantly (11.34 ± 1.87 μmol/l) (p < 0.05).

CONCLUSION

The rise and descent of plasma Hcy levels with periodontal inflammation and therapy, respectively, indicate a direct relationship of Hcy with chronic periodontitis. NSPT may be employed as an adjunctive Hcy Lowering Therapy, contributing towards primary prevention against CVD's.

The effects of normalizing hyperhomocysteinemia on clinical and operative outcomes in patients with critical limb ischemia

PURPOSE

To assess the outcome of patients with medically treated hyperhomocysteinemia (HHC) requiring intervention for critical limb ischemia (CLI).

METHODS

A parallel observational study was conducted to compare the clinical and revascularization outcomes of CLI patients who received standardized treatment for HHC preoperatively (folic acid and vitamin B12) vs. contemporaneous patients with normal homocysteine levels. The threshold for HHC diagnosis was 13.0 μmol/L. From 2009 to 2011, 169 patients underwent revascularization procedures for CLI. Of these, all 66 patients (40 men; mean age 69.6 ± 11.2 years) with HHC (mean 17.3 μmol/L, range 13.5-34.9) were treated to normalize the homocysteine level prior to lower limb revascularization. The remaining 103 patients (58 men; mean age 72.7±8.1 years) had normal homocysteine levels (8.2 μmol/L, range 5-12.3) before revascularization. The primary endpoint was symptomatic and hemodynamic improvement in the treated HHC group. The secondary endpoints were all-cause survival, binary restenosis, reintervention, amputation-free survival, and major adverse events. The treated HHC cohort was compared to an age/sex-matched historical group of patients with untreated HHC from 2002 to 2006 before HHC pretreatment became routine. All interventions (endovascular, hybrid, and open) were performed by the same surgeon, and the groups were evenly matched.

RESULTS

Patients with HHC were treated for a mean 12.2 days, which significantly reduced their mean homocysteine level after 3 weeks to 10.1 μmol/L (range 6.2-14.4, p<0.05). After revascularization, immediate clinical improvement was similar between normal homocysteine and medically corrected HHC groups. There was no significant difference in time to binary restenosis (p=0.822). Secondary endpoints and all-cause mortality were similar. Multivariate logistic regression showed that untreated HHC was a significant factor for graft occlusion and limb loss (p<0.0001), but medically corrected HHC was no longer predictive of adverse operative outcome.

CONCLUSION

Patients with medically corrected HHC have similar outcomes compared to those with normal homocysteine levels. Thus, aggressively treating HHC with folic acid and vitamin B12 may help enhance the clinical outcome of CLI patients undergoing revascularization.

Homocysteine alters cerebral microvascular integrity and causes remodeling by antagonizing GABA-A receptor

High levels of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), are associated with cerebrovascular diseases, such as vascular dementia, stroke, and Alzheimer's disease. The γ-amino butyric acid (GABA) is an inhibitory neurotransmitter and a ligand of GABA-A receptor. By inhibiting excitatory response, it may decrease complications associated with vascular dementia and stroke. Hcy specifically competes with the GABA-A receptors and acts as an excitotoxic neurotransmitter. Previously, we have shown that Hcy increases levels of NADPH oxidase and reactive oxygen species (ROS), and decreases levels of thioredoxin and peroxiredoxin by antagonizing the GABA-A receptor. Hcy treatment leads to activation of matrix metalloproteinases (MMPs) in cerebral circulation by inducing redox stress and ROS. The hypothesis is that Hcy induces MMPs and suppresses tissue inhibitors of metalloproteinase (TIMPs), in part, by inhibiting the GABA-A receptor. This leads to degradation of the matrix and disruption of the blood brain barrier. The brain cortex of transgenic mouse model of HHcy (cystathionine β-synthase, CBS-/+) and GABA-A receptor null mice treated with and without muscimol (GABA-A receptor agonist) was analysed. The mRNA levels were measured by Q-RT-PCR. Levels of MMP-2, -9, -13, and TIMP-1, -2, -3, and -4 were evaluated by in situ labeling and PCR-gene arrays. Pial venular permeability to fluorescence-labeled albumin was assessed with intravital fluorescence microscopy. We found that Hcy increases metalloproteinase activity and decreases TIMP-4 by antagonizing the GABA-A receptor. The results demonstrate a novel mechanism in which brain microvascular permeability changes during HHcy and vascular dementias, and have therapeutic ramifications for microvascular disease in Alzheimer's patients.

Why do homocysteine-lowering B vitamin and antioxidant E vitamin supplementations appear to be ineffective in the prevention of cardiovascular diseases?

Homocysteine has been established as a serious, independent risk factor for atherosclerosis. An elevated plasma homocysteine concentration is accompanied by increased cardiovascular risk; therefore, it can be assumed that lowering the plasma homocysteine level results in a decreased risk. Vitamin B complex (folic acid, and vitamins B6 and B12) substitution therapy decreases the plasma homocysteine level, inhibits oxidative stress, and ameliorates some biochemical and clinical parameters that indicate the progression of atherosclerosis. Vitamin E administration may also reduce atherogenesis through its antioxidant effect. The effectiveness of B and E vitamin substitution in decreasing cardiovascular risk has been suggested by cohort as well as prospective and retrospective studies undertaken during the last two decades. On the other hand, recent large, randomized clinical trials did not substantiate a beneficial effect of homocysteine-lowering B vitamin supplementation or vitamin E antioxidant therapies in reducing cardiovascular risk in humans. We analyzed eight B vitamin and four E vitamin trials from a critical point of view, and in this article we reviewed and commented on their results and focused on the contradictions found in them. We showed that the possible factors implicated in the failure of vitamin therapies included inappropriate designs. The protocols neglected an essential fact: that the impact of some confounding factors, such as concomitant use of statins, acetylsalicylic acid, folic acid, and other drugs, might have led to bias and an inappropriate interpretation of the data. The cardiovascular protective and preventive effects of statins and aspirin might have reduced or abolished the possibility of observing a difference in the number of events between the vitamin and placebo groups for the clinical endpoints. We concluded that the vitamin preventive effect on cardiovascular disease may not be rejected in reference to the negative trial evidence.

Hyperhomocysteinemia is Associated with Aortic Atheroma Progression in Stroke/TIA Patients

Significance: Aortic arch (AA) atheroma and AA atheroma progression are independent risk factors for recurrent vascular events in stroke/transient ischemic attack (TIA) patients. Total homocysteine level (tHcy) is an independent risk marker for atherosclerosis including that found in AA. The purpose of this study was to prospectively test the association between AA atheroma progression and tHcy. Methods: This is a cohort study of 307 consecutive hospitalized stroke/TIA patients undergoing transesophageal echocardiogram (TEE) as a part of their clinical workup. Measurable AA atheroma was detected in 167 patients of whom 125 consented to a protocol-mandated follow-up TEE at 12 months. Patients had evaluation for vascular risk factors, dietary factors (folate, B12 and pyridoxine), and methylene tetrahydrofolate reductase (MTHFR) polymorphism. One hundred eighteen stroke/TIA patients had tHcy, acceptable paired AA images, and detailed plaque measurements. An increase by ≥1 grade of AA atheroma was defined as progression. Results: Of the 118 patients, 33 (28%) showed progression and 17 (14%) showed regression of their index arch lesion at 1 year. tHcy (≥14.0 μmol/l) was significantly associated with progression on both univariate (RR = 3.4, 95% CI 2.0–5.8) and multivariate analyses (adjusted RR = 3.6, 95% CI 2.2–4.6). The changes in AA plaque thickness (r² = 0.11; p < 0.001) and AA plaque area (r² = 0.08; p = 0.002) correlated with tHcy. tHcy was associated with change in plaque thickness over 12 months, independent of age, dietary factors, renal function and MTHFR polymorphism (Standardized β-coefficient 0.335, p = 0.02). Conclusions: Our results validate the association and a linear correlation between tHcy and progression of AA atheroma.

Randomized clinical trial of folate supplementation in patients with peripheral arterial disease

BACKGROUND

The aim was to determine whether folate supplementation improved arterial function in patients with peripheral arterial disease (PAD).

METHODS

Individuals with PAD were randomly assigned to receive 400 microg folic acid (45 patients) or 5-methyltetrahydrofolate (5-MTHF) (48) daily, or placebo (40) for 16 weeks. Primary endpoints were changes in plasma total homocysteine (tHcy), ankle : brachial pressure index (ABPI) and pulse wave velocity (PWV). Secondary outcomes were changes in plasma inflammatory markers.

RESULTS

Plasma tHcy was significantly reduced in folic acid and 5-MTHF groups compared with controls: median difference: - 2.12 (95 per cent confidence interval - 3.70 to - 0.75) micromol/l (P = 0.002) and - 2.07 (-3.48 to - 0.54) micromol/l (P = 0.007) respectively. ABPI improved significantly: median difference 0.07 (0.04 to 0.11) (P < 0.001) and 0.05 (0.01 to 0.10) (P = 0.009) respectively. Brachial-knee PWV (bk-PWV) decreased significantly in individuals receiving 5-MTHF and tended to be reduced in those taking folic acid compared with controls: median difference: - 1.10 (-2.20 to - 0.20) m/s (P = 0.011) and - 0.90 (-2.10 to 0.00) m/s (P = 0.051) respectively. Plasma levels of inflammatory markers were not affected.

CONCLUSION

Folate administration reduced plasma homocysteine, and slightly improved ABPI and bk-PWV.

White blood cell count is associated with plasma total homocysteine in Japanese men

White blood cell (WBC) count has been related to risk for coronary heart disease. The relationship may be due to the association between WBC count and cardiovascular risk factors. So far, it has been shown that WBC count is associated with body mass index, total cholesterol, triglyceride, glucose, blood pressure and some lifestyle factors. It is not known, however, whether WBC count is associated with other risk factors such as total homocysteine or gamma-glutamyl transferase. The association between WBC count, total homocysteine and gamma-glutamyl transferase was analyzed cross-sectionally in middle-aged Japanese men. In a univariate regression analysis WBC count was associated positively with total homocysteine (beta (standard regression coefficient) = 0.112; p<0.001) but not with gamma-glutamyl transferase (beta = 0.033; p = 0.309). In a multivariate analysis which included cigarette smoking, physical activity, ethanol consumption, vegetable intake and body mass index, the association between WBC count and total homocysteine remained significant (beta = 0.062; p = 0.026). The association may partially explain the reported association between elevated WBC count and cardiovascular disease.

Association between vitamin B12-containing supplement consumption and prevalence of biochemically defined B12 deficiency in adults in NHANES III (third national health and nutrition examination survey)

OBJECTIVE

To explore the association between vitamin B(12) (B(12))-containing supplement use, low B(12) concentrations and biochemically defined B(12) deficiency in US adults.

DESIGN

A cross-sectional study with adjustment for survey design. Prevalence ratios for two age groups (18-50 and >50 years) were estimated using unconditional logistic models. Outcome measures included prevalence of low serum B(12) concentration (<148 pmol/l) and biochemical B(12) deficiency (serum B(12)< 148 pmol/l with concomitant homocysteine > 10 mumol/l).

SETTING

A population survey of health and nutritional measures.

SUBJECTS

Subjects were non-institutionalized adults, aged 18 years and older, who participated in Phase 2 of NHANES III (Third National Health and Nutrition Examination Survey).

RESULTS

Low B(12) concentrations were less prevalent among persons consuming B(12)-containing supplements (P = 0.001) with an adjusted prevalence ratio of 0.6 (95 % CI 0.3, 1.0). Biochemical B(12) deficiency showed a similar trend (P = 0.0002), with an adjusted prevalence ratio of 0.3 (95 % CI 0.1, 0.8). Prevalence ratios were similar in adults >50 years of age, although the prevalence of low B(12) and biochemical deficiency was proportionally higher.

CONCLUSIONS

Consumption of B(12)-containing supplements was associated with at least 50 % lower prevalence of both low serum B(12) and biochemical B12 deficiency in a nationally representative sample of US adults, suggesting increased consumption of B(12) from supplements or from fortified foods may reduce the prevalence of B(12) deficiency. Additionally, the current Recommended Daily Allowance for B(12) of 2.4 microg may be insufficient for those aged >50 years.

Longitudinal ultrasound evaluation of carotid atherosclerosis in one, two and three dimensions

The aim of this study was to compare the sensitivity of three ultrasound phenotypes of carotid atherosclerosis in a longitudinal study of patients with diabetic nephropathy. B-mode ultrasound-derived intima-media thickness (IMT), total plaque area (TPA) as well as three-dimensional ultrasound (3DUS) vessel wall volume (VWV) of the common carotid artery (CCA) (VWV(CCA)) and internal carotid artery (ICA). (VWV(CCA+ICA)) were all evaluated in subjects enrolled in a randomized placebo-controlled double blind study of vitamin B therapy. Of 106 subjects randomized, 77 subjects were scanned at baseline and 2.3 +/- 1 y later (range: 0.5 to 4.5 y); of these subjects, 71 had images of sufficient quality for complete analysis of all three measurements. Subjects were analyzed according to the two treatment groups (A and B) and the analysis was performed blinded to treatment group description to prevent any potential for bias in future analyses. There were differences in sensitivity to longitudinal changes observed in all the ultrasound measurements. Specifically, there was no difference in IMT change between treatment groups (0.02 +/- 0.07 mm/y and 0.02 +/- 0.1 mm/y p = 0.15, group A and B, respectively, rates not different from zero [p > 0.05]) or TPA rate between treatment groups (0.09 +/- 0.2 cm(2)/y, significantly different from 0, p = 0.013 and -0.02 +/- 0.3 cm(2)/y in group A and B, respectively). However, the VWV(CCA+ICA) rate of change was significantly greater than 0 for group B (53 +/- 110 mm(3)/y) (p = 0.008), which was significantly (p = 0.034) higher than the rate of change of VWV(CCA+ICA) (nonsignificant, p = 0.6) for group A (-12 +/- 137 mm(3)/y). The relationship between DeltaVWV and DeltaIMT was significant, such that in group A, DeltaVWV(CCA) was positively associated with DeltaIMT (r = 0.44, p < 0.05), and in group B, DeltaVWV(CCA) was negatively correlated with DeltaIMT (r = -0.44, p < 0.01). These results suggest that 3DUS-derived VWV provides necessary and sufficient sensitivity and specificity to measure longitudinal changes in small numbers of carotid atherosclerosis patients at risk of disease progression and over short periods of time.

Homocysteine and stroke prevention: have the trials settled the issue?

Recent publicity surrounding disappointing results of clinical trials of homocysteine lowering has led to the claim that 'homocysteine is dead'. However, there is strong evidence that elevated plasma total homocysteine is an important independent risk factor, and the highly plausible biological rationale is the following: total homocysteine increases coagulation, impairs endothelial function, increases oxidative stress and low density lipoprotein oxidation, and treatment with vitamins reverses these effects and halts progression of carotid plaque. Some studies have shown clinical benefit of vitamin therapy in coronary angioplasty and peripheral vascular disease. It has recently become apparent that vitamin B12 absorption is impaired in the elderly, and that metabolic B12 deficiency is much commoner than would be appreciated by statistical definitions of 'normal' serum B12; higher doses of B12 and perhaps other therapies such as betaine and thiols may be needed to achieve adequate reductions of total homocysteine. It remains likely that effective lowering of total homocysteine will reduce stroke and other vascular events.

Quantification of progression and regression of carotid vessel atherosclerosis using 3D ultrasound images

Atherosclerosis is an inflammatory process similar to scar formation in the inner wall of the artery. It is the underlying cause of heart attacks and some strokes. Atherosclerotic lesions in the artery wall are called plaques. 3D ultrasound (US) has been used to monitor the progression of carotid vessel plaques in symptomatic and asymptomatic patients. Different ways of measuring various ultrasound phenotypes of atherosclerosis have been developed. Here, we report on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US. In an effort to extend our previous work in plaque thickness analysis, we developed a procedure that facilitates the visualization and comparison of the distribution of plaque thickness by mapping the 3D arterial structure into a 2D plane.

Serum total homocysteine concentrations and risk of mortality from stroke and coronary heart disease in Japanese: The JACC study

Evidence for association between serum total homocysteine (tHcy) level and cardiovascular disease is limited in Asian populations. We conducted a nested case-control study under JACC Study. A total of 39,242 subjects aged 40-79 years provided serum samples at baseline surveys between 1988 and 1990. Control subjects were selected by matching for sex, age, community and year of serum storage. Serum tHcy levels were measured by high-performance liquid chromatography. During the 10-year follow-up, there were 444 deaths due to total cardiovascular disease, including 310 total stroke (131 hemorrhage and 101 ischemic strokes) and 134 coronary heart diseases. The risks of mortality from ischemic stroke, coronary heart disease, and total cardiovascular disease were significantly higher in individuals with the highest serum tHcy quartile (>or=15.3micromol/L) than in those with the lowest quartile (<10.5micromol/L); the respective multivariable odds ratios (95% CI) were 4.35 (1.12-16.9), 3.40 (1.17-9.86), and 1.68 (1.02-2.77). The multivariable odds ratios associated with a 5-micromol/L increase in tHcy were 1.49 (1.01-2.18), 2.01 (1.21-3.35), and 1.15 (1.00-1.32), respectively. High serum tHcy levels were associated with increased mortality from ischemic stroke, coronary heart disease and total cardiovascular disease among Japanese.

Homocysteine-lowering therapy: a role in stroke prevention?

On the basis of the results of several recent clinical trials, many researchers have concluded that vitamin therapy designed to lower total homocysteine concentrations is not effective in reducing the risk of cardiovascular events. However, whereas almost all myocardial infarctions are due to plaque rupture, stroke has many more pathophysiological mechanisms, and thrombosis-which is increased by raised total homocysteine concentrations-has an important role in many of these processes. Thus, stroke and myocardial infarction could respond differently to vitamin therapy. A detailed assessment of the results of the recent HOPE-2 trial and a reanalysis of the VISP trial restricted to patients capable of responding to vitamin therapy suggest that higher doses of vitamin B12 and perhaps new approaches to lowering total homocysteine besides routine vitamin therapy with folate, vitamin B6, and vitamin B12 could reduce the risk of stroke. Thus, therapy to lower homocysteine could still help to prevent stroke, if not other vascular outcomes.

Cardiac synchronous and dys-synchronous remodeling in diabetes mellitus

Glucose-mediated impairment of homocysteine (Hcy) metabolism and decrease in renal clearance contribute to hyperhomocysteinemia (HHcy) in diabetes. The Hcy induces oxidative stress, inversely relates to the expression of peroxisome proliferators activated receptor (PPAR), and contributes to diabetic complications. Extracellular matrix (ECM) functionally links the endothelium to the myocyte and is important for cardiac synchronization. However, in diabetes and hyperhomocysteinemia, a "disconnection" is caused by activated matrix metalloproteinase with subsequent accumulation of oxidized matrix (fibrosis) between the endothelium and myocyte (E-M). This contributes to "endothelial-myocyte uncoupling," attenuation of cardiac synchrony, leading to diastolic heart failure (DHF), and cardiac dys-synchronizatrion. The decreased levels of thioredoxin and peroxiredoxin and cardiac tissue inhibitor of metalloproteinase are in response to antagonizing PPARgamma.

Intensive management of risk factors for accelerated atherosclerosis: the role of multiple interventions

Patients at high risk of vascular events can reduce their risk by 75% to 80% through a combination of lifestyle changes and medical therapy. These include smoking cessation, a Mediterranean diet, daily exercise, maintaining a fit weight, moderate consumption of alcohol, effective control of blood pressure and diabetes, intensive treatment with lipid-lowering drugs and antiplatelet agents, and perhaps treatment with vitamins to lower homocysteine. Much of this is achieved primarily by the patient; physicians need to become better at assisting their patients in making lifestyle changes. Effective control of treatment-resistant hypertension can be improved by individualizing medical therapy to the underlying cause, based on measurement of plasma renin and aldosterone. Measurement of carotid plaque may be useful by providing feedback on the success of therapy.

Vital capacity and selected metabolic diseases in middle-aged Japanese men

OBJECTIVE

To elucidate the association between vital capacity and the presence of selected metabolic diseases in middle-aged Japanese men.

METHODS

A cross-sectional analysis of the associations among forced vital capacity (FVC), static vital capacity as a percentage of that predicted (%VC) and the presence of metabolic diseases was performed.

RESULTS

In a univariate linear regression analysis, FVC and %VC were inversely associated with poor vegetable intake, cigarette smoking and body mass index, but not with physical activity or ethanol consumption. In a logistic regression analysis adjusted for lifestyle factors, body mass index and age, the odds ratios for the presence of metabolic disease per 0.54 L (1 SD) decrease in FVC were 1.24 (95% CI 1.03 to 1.50) for type II diabetes, 1.21 (95% CI 1.02 to 1.42) for hypertension, 1.34 (95% CI 1.11 to 1.63) for hypertriglyceridemia, 1.23 (95% CI 1.03 to 1.46) for high gamma-glutamyl transferase levels and 1.63 (95% CI 1.10 to 2.41) for an episode of cardiovascular disease. FVC did not correlate with hyperhomocysteinemia, hypercholesterolemia or high white blood cell count. Similar results were also obtained for the association between %VC and metabolic diseases.

CONCLUSIONS

A decrease in FVC or %VC was associated with the presence of some metabolic diseases. The association may partly explain the reported association between low FVC and cardiovascular disease.

Is plasma homocysteine a modifiable risk factor for stroke?

Increased levels of plasma total homocysteine (tHcy) can be caused by genetic mutations, vitamin deficiencies, renal and other diseases, and numerous drugs. Raised tHcy also correlate with increasing age, and are associated with laboratory evidence of atherogenesis (e.g. endothelial dysfunction) and thrombosis, and with epidemiological evidence of an increased risk of atherothrombotic vascular disease, including ischemic stroke. The association between raised tHcy and increased risk of ischemic stroke is independent of other known vascular risk factors and is biologically plausible; however, randomized controlled trials have not revealed a causal relationship. The recently published Vitamins In Stroke Prevention (VISP) trial identified no significant reduction in the relative risk of stroke by lowering tHcy with B-vitamin therapy among 3,680 patients with recent ischemic stroke. It did not, however, reliably exclude a modest but important reduction of up to 20% in relative risk of stroke. Currently, there is insufficient evidence to confirm that homocysteine is a modifiable causal risk factor for stroke, or to recommend routine screening for, or treatment of, raised tHcy concentrations with folic acid and other vitamins, to prevent ischemic stroke.

Homocysteine Levels in Patients Undergoing Open-Heart Surgery

Background: The aim of this prospective study was to determine the levels of plasma homocysteine (HCY) in patients who have undergone open-heart surgery for ischemic heart disease (IHD) or nonischemic heart disease (NIHD) and to evaluate whether an association is present between hyperhomocysteinemia and coronary artery disease.Material and Methods: We investigated prospectively 30 patients who underwent open-heart surgery. Of these patients, 15 had IHD, and 15 had NIHD such as mitral and/or aortic valve disease. The 2 groups were well matched for age, sex, body mass index, and blood pressure. In all patients HCY was assayed by high performance liquid chromatography preoperatively and on the first, second, and third day postoperatively.Results: The mean age of the patients was 57.2 years in group IHD and 52.6 years in group NIHD. The male:female ratio was 8:7 in group IHD and 7:8 in group NIHD. Of 15 patients in group IHD, 13 had hyperhomocysteinemia and 2 had normal plasma HCY levels. Of 15 patients in NIHD group, 1 had hyperhomocysteinemia and the others had normal plasma HCY levels. Preoperative plasma HCY levels of all patients in the IHD group were significantly lower during all subsequent time periods, whereas preoperative plasma HCY levels in the NIHD group were lower only on the first day post-surgery (P < .05).Conclusions: Our data suggest that plasma HCY levels in patients with IHD are associated with the development of atherogenesis and coronary artery disease. For this reason, HCY levels should be measured routinely and treated appropriately in patients with risk factors for atherosclerosis.

Nutrition and Stroke Prevention

Nutrition is much more important in prevention of stroke than is appreciated by most physicians. The powerful effects of statin drugs in lowering the levels of fasting cholesterol, combined with an unbalanced focus on fasting lipids (as opposed to postprandial fat and oxidative stress), have led many physicians and patients to believe that diet is relatively unimportant. Because the statins can lower fasting lipids by &50% to 60%, and a low-fat diet only lowers fasting cholesterol by &5% to 10%, this error is perhaps understandable. However, a Cretan Mediterranean diet, which is high in beneficial oils, whole grains, fruits, and vegetables and low in cholesterol and animal fat, has been shown to reduce stroke and myocardial infarction by 60% in 4 years compared with the American Heart Association diet. This effect is twice that of simvastatin in the Scandinavian Simvastatin Survival Study: a reduction of myocardial infarction by 40% in 6 years. Vitamins for lowering of homocysteine may yet be shown to be beneficial for reduction of stroke; a key issue is the high prevalence of unrecognized deficiency of vitamin B(12), requiring higher doses of vitamin B(12) than have been used in clinical trials to date. Efforts to duplicate with supplementation the evidence of benefit for vitamins E, C, and beta carotene have been largely fruitless. This may be related to the broad combination of antioxidants included in a healthy diet. A Cretan Mediterranean diet is probably more effective because it provides a wide range of antioxidants from fruits and vegetables of all colors.

Homocysteine Hypothesis for Atherothrombotic Cardiovascular Disease

Homocysteine has been implicated in promoting atherosclerotic and thrombotic vascular disease. During the last decade, the utility of homocysteine in predicting risk for atherothrombotic vascular disease has been evaluated in several observational studies in a large number of patients. These studies show that the overall risk for vascular disease is small, with prospective, longitudinal studies reporting a weaker association between homocysteine and atherothrombotic vascular disease compared to retrospective case-control and cross-sectional studies. Furthermore, randomized controlled trials of homocysteine-lowering therapy have failed to prove a causal relationship. On the basis of these results, there is currently insufficient evidence to recommend routine screening and treatment of elevated homocysteine concentrations with folic acid and other vitamins to prevent atherothrombotic vascular disease. This review outlines the metabolism and pathophysiology of homocysteine, highlights the results of homocysteine observational and interventional trials, and presents areas of uncertainty and potential future work.

Thiol exchange: An in vitro assay that predicts the efficacy of novel homocysteine lowering therapies

Elevated plasma total homocysteine (tHcy) is a risk factor for atherosclerosis. Hcy is 70-80% bound to albumin as a disulfide. Recent trials have evaluated ability of thiol-containing drugs to exchange with protein bound Hcy and consequently increase its renal clearance. The objective of this study was to develop an in vitro assay to predict the efficacy of thiol-containing drugs to lower tHcy in the clinical setting. The assay was used to test the effects of N-acetylcysteine (NAC), mesna, captopril, dimercaptosuccinic acid (DMSA), and penicillamine. Hcy was added in vitro to plasma of healthy subjects (n = 6) and equilibrated. Concentrations of thiol exchange agent were added and incubated at 37 degrees C. Aliquots were removed at selected intervals and free Hcy determined. Mesna, captopril, and NAC caused a concentration-dependent increase in free Hcy. Three-hundred micromolar mesna and captopril had a greater effect than equimolar NAC, increasing free Hcy by 33.9 +/- 5.0% and 32.0 +/- 2.6%, respectively compared to 22.3 +/- 2.4% for NAC, p < 0.001. Our in vitro results indicate that mesna, captopril, and NAC effectively exchange with covalently bound Hcy. This assay can act as screening tool for novel tHcy lowering therapies and should spare the expense of negative trials.

GABA receptors and nitric oxide ameliorate constrictive collagen remodeling in hyperhomocysteinemia

Elevated plasma levels of homocysteine (Hcy) are associated with vascular dementias and Alzheimer's disease. The role of Hcy in brain microvascular endothelial cell (MVEC) remodeling is unclear. Hcy competes with muscimol, an gamma-amino butyric acid (GABA)-A receptor agonist. GABA is the primary inhibitory neurotransmitter in the brain. Our hypothesis is that Hcy induces constrictive microvascular remodeling by altering GABA-A/B receptors. MVEC from wild type, matrix metalloproteinase-9 (MMP-9) knockout (-/-), heterozygote cystathionine beta synthase (CBS-/+), and endothelial nitric oxide synthase knockout (eNOS-/-) mouse brains were isolated. The MVEC were incorporated into collagen (3.2 mg/ml) gels and the decrease in collagen gel diameter at 24 h was used as an index of constrictive MVEC remodeling. Gels in the absence or presence of Hcy were incubated with muscimol or baclofen, a GABA-B receptor agonist. The results suggested that Hcy-mediated MVEC collagen gel constriction was ameliorated by muscimol, baclofen, MMP-9, and eNOS gene ablations. There was no effect of anti-alpha 3 integrin. However, Hcy-mediated brain MVEC collagen constriction was abrogated with anti-beta-1 integrin. The co-incubation of Hcy with L-arginine ameliorated the Hcy-mediated collagen gel constriction. The results of this study indicated amelioration of Hcy-induced MVEC collagen gel constriction by induction of nitric oxide through GABA-A and -B receptors.

Alcohol consumption and plasma homocysteine

A few reports show that consumption of spirits and of wine correlate with elevated plasma total homocysteine (tHcy), which is associated with the risk of cardiovascular disease. We analyzed the relation between tHcy and current daily ethanol consumption cross-sectionally in middle-aged Japanese men (n = 974, age 51-59 years). Plasma tHcy was positively associated with consumption of whiskey but not with consumption of shochu (Japanese spirits), sake, beer, or wine. Odds ratios of an increase in daily intake of 30 ml ethanol (approximately 1 standard deviation) for hyperhomocysteinemia (>14.0 micromol/l) were 2.58 (95% confidence interval, 1.29-5.14) for whiskey, 1.08 (0.78-1.50) for shochu, 0.99 (0.59-1.66) for sake, 0.98 (0.58-1.63) for beer, and 1.70 (0.31-9.50) for wine in a multivariate logistic regression analysis adjusted for the daily number of cigarettes smoked, physical activity, vegetable consumption, and serum creatinine levels. After inclusion of plasma folate and vitamin B12 in the multivariate analysis model, the association between whiskey ethanol consumption and hyperhomocysteinemia remained significant with odds ratio of 2.79 (1.36-5.72). These results suggest that whiskey consumption correlates with hyperhomocysteinemia independently of plasma folate or vitamin B12 or lifestyle factors in the population studied.

Decrease of carotid intima-media thickness in patients at risk to cerebral ischemia after supplementation with folic acid, Vitamins B6 and B12

OBJECTIVE

Hyperhomocysteinemia is associated with atherosclerotic risk. Although vitamins can lower homocysteine (Hcy), information about effects on atherosclerosis is scarce.

METHODS

We used carotid intima-media thickness (IMT) as an accepted marker of atherosclerotic changes. Fifty patients (60 +/- 8 years) with IMT> or =1 mm were included. In a double blind, randomized trial they received daily 2.5 mg folic acid, 25 mg Vitamin B6, and 0.5mg Vitamin B12 or placebo for 1 year.

RESULTS

In the treatment group, Hcy decreased from 10.50 +/- 3.93 to 6.56 +/- 1.53 micromol/l (P < 0.0001), whereas it remained unchanged in the placebo group (10.76 +/- 2.36 versus 10.45+/-3.30 micromol/l). IMT decreased from 1.50 +/- 0.44 to 1.42 +/- 0.48 mm (P = 0.034) in the treatment group, whereas it increased from 1.47 +/- 0.57 to 1.54 +/- 0.71 mm in the placebo group. The mean individual changes of IMT between both groups differed significantly (-0.08 +/- 0.17 versus 0.07 +/- 0.25 mm, P = 0.019). Multiple regression analysis revealed that the observed effect on IMT depended only on medication.

CONCLUSIONS

Vitamin supplementation significantly reduces IMT in patients at risk. This effect is independent of Hcy concentration.

Quantification of carotid plaque volume measurements using 3D ultrasound imaging

An accurate and reliable technique used to quantify carotid plaque volume has practical importance in research and patient management. In this study, we develop and investigate a theoretical description of carotid plaque volume measurements made using three-dimensional (3D) ultrasound (US) images and compare it with experimental results. Multiple observers measured 48 3D US patient images of carotid plaque (13.2 to 544.0 mm(3)) by manual planimetry. Coefficients of variation in the measurement of plaque volume were found to decrease with increasing plaque size for both inter- (90.8 to 3.9%) and intraobserver (70.2 to 3.1%) measurements. Plaque volume measurement variability was found to increase with interslice distance (ISD), while the relative measurement accuracy remained constant for ISDs between 1.0 and 3.0 mm and then decreased. Root-mean-square (RMS) difference between our theoretical description of plaque volume measurement variance and the experimental results was 5.7%. Thus, our results support the clinical utility of measuring carotid plaque volume by manual planimetry noninvasively using 3D US.

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.

Clinical usefulness of plasma homocysteine in vascular disease

Raised plasma homocysteine (tHcy) concentrations are caused by genetic mutations, vitamin deficiencies, renal and other diseases, numerous drugs, and increasing age. Raised tHcy concentrations are associated with laboratory evidence of atherogenesis (eg, endothelial dysfunction) and thrombosis, and epidemiological evidence of an increased risk of atherothrombotic vascular disease. An association between raised tHcy concentration and an increased risk of atherothrombosis is independent of other vascular risk factors, strong, dose-related and biologically plausible, but has not been proven to be causal in randomised controlled trials. A recent trial identified no significant benefit from lowering tHcy concentration by folic-acid-based multivitamin therapy among 3680 patients with recent ischaemic stroke, but did not reliably exclude a modest but important reduction in the relative risk of stroke of up to 20%; a difference of only 2 mmol/L in tHcy concentration between the two treatment groups was probably due to widespread vitamin use and fortification of grains and staple foods with folate in North America. There is currently insufficient evidence to recommend routine screening and treatment of high tHcy concentrations with folic acid and other vitamins to prevent atherothrombotic vascular disease.

Homocysteine, B-vitamin supplementation, and stroke prevention: from observational to interventional trials

BACKGROUND

Homocysteine is an amino acid, the metabolism of which is linked to that of several vitamins-especially folic acid, B6, and B12. A high concentration of homocysteine in the plasma is linked to vascular disease, including stroke. Concentrations of homocysteine can be inexpensively and safely lowered by treatment with a combination of folate, vitamin B12, and vitamin B6. However, whether the association between high plasma concentrations of homocysteine and vascular disease is causal is unclear.

RECENT DEVELOPMENTS

Two studies have assessed the relation between dietary or supplementary B vitamin intake on the risk of stroke. In a prospective observational study of 43?732 healthy men, there was an inverse relation between dietary folate intake and the risk of ischaemic stroke. The Vitamin Intervention for Stroke Prevention study (VISP) was the first large-scale randomised interventional study that investigated the lowering of homocysteine concentrations with B vitamins in patients with ischaemic stroke. There was an association between baseline homocysteine concentrations and vascular risk in this trial. Plasma concentrations of homocysteine were only modestly reduced by high-dose versus low-dose formulation, and there was no treatment effect on recurrent stroke, coronary events, or deaths. Limitations of VISP included that only patients with mild increases in baseline homocysteine concentrations were studied, only modest reductions of homocysteine concentrations were achieved, and follow up was short. In addition, fortification of food with folate and treatment of low vitamin-B12 concentrations may have masked the effect of treatment on stroke risk. WHAT NEXT?: When exposure can be safely assigned at random, as in the case of B-vitamin therapy, randomised trials should be the standard proof to determine the effect of therapy. The results of the first randomised clinical trial of B vitamins for secondary prevention of stroke were neutral. Larger trials with longer follow-up, selection of patients with higher plasma concentrations of homocysteine, and systematic assessment of cognitive functions and dementia are needed. In the meantime, homocysteine-lowering treatment that is cheap and well-tolerated should be considered a rational approach in patients at high risk of stroke and high concentrations of homocysteine.

Large-artery stroke in a young patient with Crohn's disease. Role of vitamin B6 deficiency-induced hyperhomocysteinemia

An increased incidence of ischemic stroke has been reported in patients with Crohn's disease. Cerebral infarcts are usually considered as a complication of the hypercoagulable state associated with this inflammatory bowel disease (IBD). The association between Crohn's disease, hyperhomocysteinemia and large-artery stroke of the young has rarely been reported. A 39-year-old woman, with prior medical history of Crohn's disease and hypertension, presented with an ischemic stroke of the left internal carotid artery (ICA) territory. Etiological workup disclosed bilateral high-grade ICA stenosis and atheroma of the subclavian and vertebral arteries. Exhaustive search for prothrombotic factors showed inflammation, with an increased level of fibrinogen and factor IX, and a marked hyperhomocysteinemia. Both vitamin B1 and vitamin B6 plasmatic levels were decreased. Heterozygous C677T methylene-tetrahydrofolate reductase gene mutation was present. This observation highlights the combined proatherogenic effect of vitamin B deficiency-induced hyperhomocysteinemia and inflammation leading to large-artery stroke of the young in the setting of Crohn's disease. Our case report stresses the importance of vitamin deficiency screening in patients with IBD in terms of stroke prevention.

Progress in Clinical Neurosciences: Pharmacotherapies for the Secondar Prevention of Stroke

Stroke is a leading cause of mortality and long-term disability worldwide. Survivors of a previous stroke or transient ischemic attack are vulnerable to further cerebrovascular events, as well as myocardial infarction, peripheral vascular disease, congestive heart failure and vascular death. Traditional approaches to the secondary prevention of stroke have included aspirin after ischemic stroke, warfarin for stroke associated with cardioembolic sources, and carotid endarterectomy for eligible candidates with significant carotid artery stenosis. In recent years, much evidence has emerged to support a broader array of pharmacotherapies, including newer antiplatelet agents, lipid lowering drugs, and several classes of blood pressure lowering therapies. Also under study are B vitamins for patients with cerebrovascular disease and hyper-homocysteinemia, and oral direct thrombin inhibitors for high-risk patients with atrial fibrillation. We review the literature to determine the clinical significance of these therapies, and provide recommendations regarding their use in the prevention of recurrent stroke.

Homocysteine and cardiovascular disease: biological mechanisms, observational epidemiology, and the need for randomized trials

Basic research indicates that homocysteine causes endothelial dysfunction and damage, accelerates thrombin formation, inhibits native thrombolysis, promotes lipid peroxidation through free radical formation, and induces vascular smooth muscle proliferation and monocyte chemotaxis. Most, but not all, observational epidemiological studies indicate that individuals with higher homocysteine levels have increased risks of cardiovascular disease. The magnitude ranges from approximately 20% in prospective studies to approximately 80% in retrospective case-control studies. In all observational epidemiological studies, however, the amount of uncontrolled and uncontrollable confounding is as large as the postulated small to moderate effect size. Thus, the totality of evidence should include randomized trials of sufficient sample size and duration with clinical end points. Folic acid reduces levels of homocysteine, but at present, despite several plausible biological mechanisms and a large body of observational epidemiological data, it is unclear whether supplementation will reduce risks of cardiovascular disease. It is also unclear whether any benefit of folic acid is attributable to lowering homocysteine levels. The current evidence is necessary, but not sufficient to judge causality. Such judgments await the availability of data from large-scale randomized trials. The availability of such data would permit rational clinical decision-making for individual patients and policy decisions for the health of the general public.

Evidence for a protective (synergistic?) effect of B-vitamins and omega-3 fatty acids on cardiovascular diseases

The results of dietary intervention trials favor the hypothesis that higher intakes of B-vitamins (folate, vitamin B(6) and B(12)), and subsequently lower total homocysteine (tHcy) concentrations, are causally associated with a decreased risk of vascular disease in patients with cardiovascular diseases (CVD). The same is true for a higher intake of omega-3 fish fatty acids. Yet, the lack of hard end points and/or appropriate study designs precludes a definitive conclusion about causality. In the future, intervention trials with hard end points and randomized double-blind placebo-controlled designs should be able to elucidate the causality problem. There are several pathways by which B-vitamins and omega-3 fatty acids may exert their protective effect on CVD, a common pathway is a beneficial effect on the endothelial function and hemostasis. With respect to synergy between B-vitamins and omega-3 fatty acids, there is no evidence that fish oils have a tHcy-lowering effect beyond the effect of the B-vitamins. Nevertheless, animal studies clearly illustrate that vitamin B(6)- as well as folate-metabolism are linked with those of long-chain omega-3 fatty acids. Furthermore, a human study indicated synergistic effects of folic acid (synthetic form of folate) and vitamin B(6) together with omega-3 fatty acids on the atherogenic index and the fibrinogen concentration. Although these results are promising, they were produced in very small selective study populations. Thus, confirmation in large well-designed intervention trials is warranted.

Young stroke and basal plasma and post-methionine load homocysteine and cysteine levels 1 year after the acute event: do plasma folates make the difference?

We conducted a case-control study to evaluate the relationship between ischemic stroke in young adults (<45 years of age) and plasma homocysteine (Hcy), plasma folate and vitamin B(12), after a methionine load. We studied 42 patients with a history of ischemic stroke and 29 controls with a negative clinical history of cardio- or cerebrovascular diseases, venous thrombosis and renal disease. A fasting blood sample was drawn from each participant; the second and third samples were collected, respectively, 120 and 240 min after the methionine load. Whilst there was no difference between controls and patients in basal total homocysteine (tHcy), we found a statistically significant difference in both the 120- and 240-min samples. We compared the basal and 240-min tHcy in patients and controls. We obtained a median value of 17.8 and 11.6 micromol/l in patients and controls, respectively. The difference between these two values was highly significant. The methionine loading test (MLT) reveals Hcy metabolism abnormalities that were not revealed by the basal sample. MLT may help identify and treat this new risk factor, which seems to be both atherogenic and prothrombotic, and is hypothesized to operate through various mechanisms.

Measurement of carotid plaque volume by 3-dimensional ultrasound

BACKGROUND AND PURPOSE

Measurement of carotid plaque volume and its progression are important tools for research and patient management. In this study, we investigate the observer variability in the measurement of plaque volume as determined by 3-dimensional (3D) ultrasound (US). We also investigate the effect of interslice distances (ISD) and repeated 3D US scans on measurement variability. Materials and Methods Forty 3D US patient images of plaques (range, 37.43 to 604.1 mm3) were measured by manual planimetry. We applied ANOVA to determine plaque volume measurement variability and reliability. Plaque volumes were measured with 9 ISDs to determine the effect of ISD on measurement variability. Additional plaque volumes were also measured from multiple 3D US scans to investigate repeated scan acquisition variability. Results Intraobserver and interobserver measurement reliabilities were 94% and 93.2%, respectively. Plaque volume measurement variability decreased with increasing plaque volume (range, 27.1% to 2.2%). Measurement precision was constant for ISDs between 1.0 and 3.0 mm, whereas plaque volume measurement variability increased with ISD. Repeated 3D US scan measurements were not different from single-scan measurements (P=0.867). Conclusions The coefficient of variation in the measurement of plaque volume decreased with plaque size. The volumetric change that must be observed to establish with 95% confidence that a plaque has undergone change is approximately 20% to 35% for plaques <100 mm3 and approximately 10% to 20% for plaques >100 mm3. Measurement precision was unchanged for ISDs <3.0 mm, whereas measurement variability increased with ISD. Repeated 3D US scans did not affect plaque volume measurement variability.

The Women's Antioxidant Cardiovascular Study: Design and Baseline Characteristics of Participants

BACKGROUND

The evidence for a potential benefit of antioxidant vitamins and folic acid in cardiovascular disease (CVD) prevention is derived from laboratory, clinical, and observational epidemiological studies but remains inconclusive. Large-scale randomized trials with clinical end points are necessary to minimize confounding and provide unbiased estimates of the balance of benefits and risks, yet data from such trials are scarce, especially among women.

METHODS

The Women's Antioxidant Cardiovascular Study (WACS) is a randomized, double-blind, placebo-controlled trial testing whether antioxidant vitamins and a folic acid/vitamin B(6)/vitamin B(12) combination prevent future cardiovascular events among women with preexisting CVD or >or=3 CVD risk factors. This paper describes the design of the trial and baseline characteristics of participants, evaluates the success of randomization, and addresses the generalizability of future findings.

RESULTS

In a factorial design, 8171 U.S. female health professionals aged >or=40 years were randomized to vitamin E, vitamin C, beta-carotene, or placebos. Of these women, 5442 were also subsequently randomized to folic acid/vitamin B(6)/vitamin B(12) or placebo. The randomization was successful, as evidenced by similar distributions of baseline demographic, health, and behavioral characteristics across treatment groups. The clinical profile of participants was similar to that observed in another large trial of women with CVD.

CONCLUSIONS

The similar distribution of known potential confounders across treatment groups provides reassurance that unmeasured or unknown potential confounders are also equally distributed. Although a definitive conclusion regarding generalizability requires additional trials in diverse populations, there is little biological basis for supposing that the benefit-risk balance differs in other high-risk women.