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

A Label-Free Electrochemical Biosensor for Homocysteine Detection Using Molecularly Imprinted Polymer and Nanocomposite-Modified Electrodes

An essential biomarker for the early detection of cardiovascular diseases is serum homocysteine (Hcy). In this study, a molecularly imprinted polymer (MIP) and nanocomposite were used to create a label-free electrochemical biosensor for reliable Hcy detection. A novel Hcy-specific MIP (Hcy-MIP) was synthesized using methacrylic acid (MAA) in the presence of trimethylolpropane trimethacrylate (TRIM). The Hcy-MIP biosensor was fabricated by overlaying the mixture of Hcy-MIP and the carbon nanotube/chitosan/ionic liquid compound (CNT/CS/IL) nanocomposite on the surface of a screen-printed carbon electrode (SPCE). It showed high sensitivity, with a linear response of 5.0 to 150 µM (R² of 0.9753) and with a limit of detection (LOD) at 1.2 µM. It demonstrated low cross-reactivity with ascorbic acid, cysteine, and methionine. Recoveries of 91.10-95.83% were achieved when the Hcy-MIP biosensor was used for Hcy at 50-150 µM concentrations. The repeatability and reproducibility of the biosensor at the Hcy concentrations of 5.0 and 150 µM were very good, with coefficients of variation at 2.27-3.50% and 3.42-4.22%, respectively. This novel biosensor offers a new and effective method for Hcy assay compared with the chemiluminescent microparticle immunoassay at the correlation coefficient (R²) of 0.9946.

Effects of Coffee Supplementation on Homocysteine and Leptin Levels: A Systematic Review and Meta-analysis of Clinical Trials

BACKGROUND

It has been reported that the consumption of antioxidant foods and beverages may benefit the development of cardiovascular risk factors. However, the impact of coffee consumption on some of these factors, such as homocysteine and leptin is controversial. Some clinical trials have suggested that coffee administration increases plasma total homocysteine levels, while others have found no significant changes in leptin concentrations.

OBJECTIVE

This study aimed to assess the effects of coffee supplementation on homocysteine and leptin concentrations in a meta-analysis of clinical trials.

METHODS

PubMed, Web of Science, Scopus, ClinicalTrials.gov, and Google Scholar databases were searched from inception to September 29, 2021. A fixed-effects model and the generic inverse variance weighting method were used for meta-analysis.

RESULTS

The meta-analysis demonstrated that coffee administration significantly increases homocysteine levels (WMD: 0.55 μmol/L, 95% CI: 0.17, 0.93, p = 0.005, I2 = 0%) but has no significant changes in leptin concentrations (WMD: 1.34 ng/mL, 95% CI: -0.78, 3.45, p = 0.21, I2 = 0%). Additionally, the sensitivity analysis was robust for both homocysteine and leptin levels.

CONCLUSION

The results of the present meta-analysis revealed that coffee supplementation raises serum homocysteine concentrations but has no effect on circulating leptin levels.

SARS-CoV-2 Infection: What Is Currently Known about Homocysteine Involvement?

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world causing health, social and economic instability. The severity and prognosis of patients with SARS-CoV-2 infection are associated with the presence of comorbidities such as cardiovascular disease, hypertension, chronic lung disease, cerebrovascular disease, diabetes, chronic kidney disease, and malignancy. Thrombosis is one of the most serious complications that can occur in patients with COVID-19. Homocysteine is a non-proteinogenic α-amino acid considered a potential marker of thrombotic diseases. Our review aims to provide an updated analysis of the data on the involvement of homocysteine in COVID-19 to highlight the correlation of this amino acid with disease severity and the possible mechanisms by which it intervenes.

Sortilin and Homocysteine as Potential Biomarkers for Coronary Artery Diseases

Purpose

The aim of this study was to assess the relationship of coronary artery disease (CAD) with levels of homocysteine and sortilin in Egyptian patients.

Background

CAD is a primary contributor to cardiac disease and a prominent cause of death globally.

Patients and Methods

We enrolled 45 patients with CAD evaluated by coronary CT angiography and 42 control subjects without CAD. Plasma-homocysteine and -sortilin levels were measured with a commercial ELISA kit.

Results

Elevated levels of homocysteine and sortilin were observed in the CAD patients compared to controls (13.75±1.40 vs 7.73±2.06 μmol/L, P=0 and 160.91±32.17 vs 143.02±32.30 ng/dL, P=0.02, respectively). Significantly higher total cholesterol, low density–lipoprotein cholesterol and triglycerides (P<0.05) and lower high density–lipoprotein cholesterol (P<0.05) were seen among patients with CAD than the control group. Sortilin levels were positively associated with homocysteine levels (r=0.32, P=0.006), total cholesterol (r=0.61, P=0), low density–lipoprotein cholesterol (r=0.37, P=0.001), triglycerides (r=0.91, P=0), troponin I (r=0.82, P=0), Gensini score (r=0.93, P=0) and high-sensitivity CRP (r=0.87, P=0) in all subjects. Homocysteine has a significantly negative association with high density–lipoprotein cholesterol (r=−0.42, P=0).

Conclusion

Elevated homocysteine and sortilin levels are crucial risk factors of CAD in Egyptian patients.

Effects of MTHFR C677T polymorphism on vitamin D, homocysteine and natural killer cell cytotoxicity in women with recurrent pregnancy losses

STUDY QUESTION

Is there any relationship between vitamin D [25 (OH) vitamin D], total plasma homocysteine and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in women with recurrent pregnancy losses (RPL)?

SUMMARY ANSWER

Women with MTHFR 677TT (homozygous mutation, TT) genotype have significantly lower vitamin D levels, higher homocysteine and natural killer (NK) cell cytotoxicities than those of women with MTHFR 677CC (wild type, CC) and 677CT (heterozygous mutation, CT) genotypes.

WHAT IS KNOWN ALREADY

Vitamin D insufficiency, MTHFR C677T polymorphism and hyperhomocysteinemia have been reported as risk factors for RPL. However, the relationship between these risk factors is not known in this population.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cross-sectional study, including 837 women with RPL, who were enrolled in Reproductive Medicine and Immunology, Chicago Medical School, between 2012 and 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women with two or more RPL prior to 20 weeks of gestation were included. To investigate whether the MTHFR C677T polymorphism affects the levels of homocysteine and vitamin D as well as immune parameters in women with RPL, biochemical data, such as plasma total homocysteine and serum vitamin D levels, and immune parameters, including NK cell cytotoxicity, were analyzed by MTHFR C677T genotype (CC, CT and TT).

MAIN RESULTS AND THE ROLE OF CHANCE

The serum level of vitamin D in TT was significantly lower when compared with those of CT (P = 0.001) and CC (P = 0.003), while the level of homocysteine in TT was significantly higher than those in CT (P = 0.01) and CC (P = 0.01). NK cytotoxicity in TT was significantly higher than that of CC (P = 0.04) but not CT (P = 0.09). There was a significant negative correlation between the levels of vitamin D and homocysteine in TT (r = -0.357, P < 0.01). In multivariate analysis, vitamin D insufficiency (<30 ng/ml) was an independent risk factor for hyperhomocysteinemia (adjusted odds ratio 1.89, 95% CI 1.41-2.52).

LIMITATIONS, REASONS FOR CAUTION

The study was retrospective and included only women with RPL but not healthy fertile controls. In addition, folic acid, vitamin B6 and B12 intake, which could modify the level of homocysteine and vitamin D, were not investigated. Thus, a considerable part of women might have folic acid and vitamin D supplementation and prenatal vitamin pills, and there are probable confounders in this study associated with unrestricted vitamin supplementation. Therefore, the findings should be carefully interpreted and applied to RPL women with MTHFR gene polymorphism.

WIDER IMPLICATIONS OF THE FINDINGS

The findings attained in this analysis regarding the MTHFR polymorphism and its relationship with vitamin D, homocysteine and NK cytotoxicity may aid in uncovering the underlying etiology and mechanism for RPL. The study highlights an interplay between nutrition and immune responses in RPL.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received for this study. None of the authors have any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Unexplored nutritive potential of tomato to combat global malnutrition

Tomato, a widely consumed vegetable crop, offers a real potential to combat human nutritional deficiencies. Tomatoes are rich in micronutrients and other bioactive compounds (including vitamins, carotenoids, and minerals) that are known to be essential or beneficial for human health. This review highlights the current state of the art in the molecular understanding of the nutritional aspects, conventional and molecular breeding efforts, and biofortification studies undertaken to improve the nutritional content and quality of tomato. Transcriptomics and metabolomics studies, which offer a deeper understanding of the molecular regulation of the tomato's nutrients, are discussed. The potential uses of the wastes from the tomato processing industry (i.e., the peels and seed extracts) that are particularly rich in oils and proteins are also discussed. Recent advancements with CRISPR/Cas mediated gene-editing technology provide enormous opportunities to enhance the nutritional content of agricultural produces, including tomatoes. In this regard, genome editing efforts with respect to biofortification in the tomato plant are also discussed. The recent technological advancements and knowledge gaps described herein aim to help explore the unexplored nutritional potential of the tomato.

Lipid lowering therapy in cardiovascular disease: From myth to molecular reality

Lipid-lowering therapy is one major cornerstone of medical treatment of cardiovascular disease in order to modulate atherosclerosis. Statins, ezetimibe and novel PCSK9-inhibitors are already recommended in current guidelines and were shown to improve lipid profiles and have positive effects on the rate of ischemic events and cardiovascular mortality. Recent studies suggest that the concept of "The lower the better" might be valid at least regarding low density lipoproteins. In addition, lowering lipoprotein (a) still displays a major challenge in lipid therapy. Furthermore, also lowering triglycerides seems to improve cardiovascular outcome. Regarding triglycerides, icosapent ethyl, a polyunsaturated fatty acid recently attracted attention showing cardiovascular risk reduction due to triglyceride lowering. Therefore, new therapeutic strategies and drug classes are eagerly awaited. Targeting LDL, bempedoic acid and the siRNA inclisiran provide promising results. Moreover, regarding TG a monoclonal antibody called evinacumab and an antisense-oligonucleotide against ANGPTL3 showed effective TG-lowering. At least, using antisense-oligonucleotides against ApoC-III and Lp(a) resulted in promising outcomes. In this review, current and future options for lipid management are presented depending on different drug classes.

Potential nutraceutical and food additive properties and risks of coffee: a comprehensive overview

Coffee is a composite mixture of more than a thousand diverse phytochemicals like alkaloids, phenolic compounds, vitamins, carbohydrates, lipids, minerals and nitrogenous compounds. Coffee has multifunctional properties as a food additive and nutraceutical. As a nutraceutical, coffee has anti-inflammatory, anti-oxidant, antidyslipidemic, anti-obesity, type-2 diabetes mellitus (DM), and cardiovascular diseases (CVD), which can serve for the treatment and prevention of metabolic syndrome and associated disorders. On the other hand, as a food additive, coffee has antimicrobial activity against a wide range of microorganisms, inhibits lipid peroxidation (LPO), and can function as a prebiotic. The outcomes of different studies also revealed that coffee intake may reduce the incidence of numerous chronic diseases, like liver disease, mental health, and it also overcomes the all-cause mortality, and suicidal risks. In some studies, high intake of coffee is linked to increase CVD risk factors, like cholesterol, plasma homocysteine and blood pressure (BP). There is also a little evidence that associated the coffee consumption with increased risk of lung tumors in smokers. Among adults who consume the moderate amount of coffee, there is slight indication of health hazards with strong indicators of health benefits. Moreover, existing literature suggests that it may be cautious for pregnant women to eliminate the chances of miscarriages and impaired fetal growth. The primary purpose of this narrative review is to provide an overview of the findings of the positive impacts and risks of coffee consumption on human health. In conclusion, to date, the best available evidence from research indicates that drinking coffee up to 3-4 cups/day provides health benefits for most people.

Translational Aspects of Sphingolipid Metabolism in Renal Disorders

Sphingolipids, long thought to be passive components of biological membranes with merely a structural role, have proved throughout the past decade to be major players in the pathogenesis of many human diseases. The study and characterization of several genetic disorders like Fabry’s and Tay Sachs, where sphingolipid metabolism is disrupted, leading to a systemic array of clinical symptoms, have indeed helped elucidate and appreciate the importance of sphingolipids and their metabolites as active signaling molecules. In addition to being involved in dynamic cellular processes like apoptosis, senescence and differentiation, sphingolipids are implicated in critical physiological functions such as immune responses and pathophysiological conditions like inflammation and insulin resistance. Interestingly, the kidneys are among the most sensitive organ systems to sphingolipid alterations, rendering these molecules and the enzymes involved in their metabolism, promising therapeutic targets for numerous nephropathic complications that stand behind podocyte injury and renal failure.

Methionine-supplemented diet affects the expression of cardiovascular disease-related genes and increases inflammatory cytokines in mice heart and liver

Some important environmental factors that influence the development of cardiovascular diseases (CVD) include tobacco, excess alcohol, and unhealthy diet. Methionine obtained from the diet participates in the synthesis of DNA, proteins, lipids and affects homocysteine levels, which is associated with the elevated risk for CVD development. Therefore, the aim of this study was to investigate the manner in which dietary methionine might affect cellular mechanisms underlying CVD occurrence. Swiss albino mice were fed either control (0.3% DL-methionine), methionine-supplemented (2% DL-methionine), or a methionine-deprived diet (0% DL-methionine) over a 10-week period. The parameters measured included plasma homocysteine concentrations, oxidative stress by reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, levels of inflammatory cytokines IL-1ß, TNF-α, and IL-6, as well as expression of genes associated with CVD. The levels of apolipoprotein A5 (APOA5), a regulator of plasma triglycerides, were measured. The methionine-supplemented diet increased oxidative stress by lowering the GSH/GSSG ratio in heart tissues and decreased expression of the genes Apob, Ctgf, Serpinb2, Spp1, Il1b, and Sell, but elevated expression of Thbs4, Tgfb2, Ccr1, and Vegfa. Methionine-deprived diet reduced expression of Col3a1, Cdh5, Fabp3, Bax, and Hbegf and increased expression of Sell, Ccl5, Itga2, Birc3, Msr1, Bcl2a1a, Il1r2, and Selp. Methionine-deprived diet exerted pro-inflammatory consequences as evidenced by elevated levels of cytokines IL-1ß, TNF-α, and IL-6 noted in liver. Methionine-supplemented diet increased hepatic IL-6 and cardiac TNF-α. Both methionine supplementation and deprivation lowered hepatic levels of APOA5. In conclusion, data demonstrated that a methionine-supplemented diet modulated important biological processes associated with high risk of CVD development.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease, which includes coronary artery disease, stroke and peripheral vascular disease, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor for cardiovascular disease is an elevated circulating total homocysteine level. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events has been investigated. This is an update of a review previously published in 2009, 2013, and 2015.

OBJECTIVES

To determine whether homocysteine-lowering interventions, provided to patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as reducing all-cause mortality, and to evaluate their safety.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (1946 to 1 June 2017), Embase (1980 to 2017 week 22) and LILACS (1986 to 1 June 2017). We also searched Web of Science (1970 to 1 June 2017). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We calculated the number needed to treat for an additional beneficial outcome (NNTB). We measured statistical heterogeneity using the I2 statistic. We used a random-effects model. We conducted trial sequential analyses, Bayes factor, and fragility indices where appropriate.

MAIN RESULTS

In this third update, we identified three new randomised controlled trials, for a total of 15 randomised controlled trials involving 71,422 participants. Nine trials (60%) had low risk of bias, length of follow-up ranged from one to 7.3 years. Compared with placebo, there were no differences in effects of homocysteine-lowering interventions on myocardial infarction (homocysteine-lowering = 7.1% versus placebo = 6.0%; RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I2 = 0%, 12 trials; N = 46,699; Bayes factor 1.04, high-quality evidence), death from any cause (homocysteine-lowering = 11.7% versus placebo = 12.3%, RR 1.01, 95% CI 0.96 to 1.06, I2 = 0%, 11 trials, N = 44,817; Bayes factor = 1.05, high-quality evidence), or serious adverse events (homocysteine-lowering = 8.3% versus comparator = 8.5%, RR 1.07, 95% CI 1.00 to 1.14, I2 = 0%, eight trials, N = 35,788; high-quality evidence). Compared with placebo, homocysteine-lowering interventions were associated with reduced stroke outcome (homocysteine-lowering = 4.3% versus comparator = 5.1%, RR 0.90, 95% CI 0.82 to 0.99, I2 = 8%, 10 trials, N = 44,224; high-quality evidence). Compared with low doses, there were uncertain effects of high doses of homocysteine-lowering interventions on stroke (high = 10.8% versus low = 11.2%, RR 0.90, 95% CI 0.66 to 1.22, I2 = 72%, two trials, N = 3929; very low-quality evidence).We found no evidence of publication bias.

AUTHORS' CONCLUSIONS

In this third update of the Cochrane review, there were no differences in effects of homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo on myocardial infarction, death from any cause or adverse events. In terms of stroke, this review found a small difference in effect favouring to homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination comparing with placebo.There were uncertain effects of enalapril plus folic acid compared with enalapril on stroke; approximately 143 (95% CI 85 to 428) people would need to be treated for 5.4 years to prevent 1 stroke, this evidence emerged from one mega-trial.Trial sequential analyses showed that additional trials are unlikely to increase the certainty about the findings of this issue regarding homocysteine-lowering interventions versus placebo. There is a need for additional trials comparing homocysteine-lowering interventions combined with antihypertensive medication versus antihypertensive medication, and homocysteine-lowering interventions at high doses versus homocysteine-lowering interventions at low doses. Potential trials should be large and co-operative.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

Hyperhomocysteinemia exacerbates Alzheimer's disease pathology by way of the β-amyloid fibrinogen interaction

Essentials Evidence suggests a comorbidity between hyperhomocysteinemia (HHC) and Alzheimer's disease (AD). Homocysteine (HC) could affect the β-amyloid (Aβ)-fibrinogen interaction in AD pathology. AD patients with concomitant HHC have increased fibrin and Aβ deposits in their brains. HC contributes to AD pathology via the Aβ-fibrinogen interaction.

SUMMARY

Background Accumulating clinical evidence suggests that hyperhomocysteinemia (HHC) is correlated with Alzheimer's disease (AD) and vascular dementia. Objective This study was carried out to elucidate the specific role of elevated homocysteine (HC) levels in AD pathophysiology. Methods Immunohistochemistry was used to examine β-amyloid (Aβ) deposition along blood vessels, also known as cerebral amyloid angiopathy (CAA), fibrin(ogen) deposition, and their correlation to each other in the brains of AD patients with and without HHC. To study AD-HHC co-morbidity in detail, an AD mouse model was administered a high methionine diet for several months. Parenchymal Aβ plaques, CAA-positive vessels and fibrin deposits were then assessed by immunohistochemistry at different stages of AD progression. Memory deficits were evaluated with contextual fear conditioning and the Barnes maze. Additionally, the effect of HC and its metabolite, homocysteine thiolactone (HCTL), on the Aβ-fibrinogen interaction was analyzed by pull-down, ELISA and fibrin clot formation and fibrinolysis assays in vitro. Results We found increased fibrin(ogen) levels and Aβ deposits in the blood vessels and brain parenchyma of AD patients with HHC. We demonstrate that HC and HCTL enhance the interaction between fibrinogen and Aβ, promote the formation of tighter fibrin clots and delay clot fibrinolysis. Additionally, we show that diet-induced HHC in an AD mouse model leads to severe CAA and parenchymal Aβ deposition, as well as significant impairments in learning and memory. Conclusions These findings suggest that elevated levels of plasma HC/HCTL contribute to AD pathology via the Aβ-fibrin(ogen) interaction.

The effect of soy or isoflavones on homocysteine levels: a meta-analysis of randomised controlled trials

BACKGROUND

The present study aimed to evaluate the effect of soy or isoflavones on blood homocysteine levels via a systematic review and meta-analysis.

METHODS

Pubmed, Embase, Web of Science and the Cochrane Library (up to 16 December 2015) were used for the literature review. Only randomised controlled trials were included. The primary outcome was the standard mean difference (SMD) of blood homocysteine levels between the experimental and control groups.

RESULTS

Nineteen randomised controlled studies were included for qualitative analysis. Eighteen studies were included in the data synthesis. Soy or isoflavones were found to have no effect on homocysteine levels, with a SMD of -0.21 (95% confidence interval = -0.43 to 0.00, I² =67.7%, random effect model). No publication bias was found among those studies (P = 0.296 for Egger's test, and P = 0.198 for Begg's test).

CONCLUSIONS

Soy or isoflavones were not found to be associated with a reduction in homocysteine levels. Further studies might still be needed in carefully selected populations.

Glucose tolerance and cardiovascular risk biomarkers in non-diabetic non-obese obstructive sleep apnea patients: Effects of long-term continuous positive airway pressure

BACKGROUND

Insulin resistance, glucose dyshomeostasis and oxidative stress are associated to the cardiovascular consequences of obstructive sleep apnea (OSA). The effects of a long-term continuous positive airway pressure (LT-CPAP) treatment on such mechanisms still remain conflicting.

OBJECTIVE

To investigate the effect of LT-CPAP on glucose tolerance, insulin sensitivity, oxidative stress and cardiovascular biomarkers in non-obese non-diabetic OSA patients.

PATIENTS & METHODS

Twenty-eight apneic, otherwise healthy, men suffering from OSA (mean age = 48.9 ± 9.4 years; apnea-hypopnea index = 41.1 ± 16.1 events/h; BMI = 26.6 ± 2.8 kg/m(2); fasting glucose = 4.98 ± 0.37 mmol/L) were evaluated before and after LT-CPAP by an oral glucose tolerance test (OGTT), measuring plasma glucose, insulin and proinsulin. Glycated hemoglobin, homeostasis model assessment resistance insulin, blood lipids, oxidative stress, homocysteine and NT-pro-brain natriuretic peptide (NT-proBNP) were also measured.

RESULTS

LT-CPAP treatment lasted 13.9 ± 6.5 months. At baseline, the time spent at SaO2<90%, minimal and mean SaO2 were associated with insulin area under the curve during OGTT (r = 0.448, P = 0.011; r = -0.382; P = 0.047 and r = -0.424; P = 0.028, respectively) and most other glucose/insulin homeostasis biomarkers, as well as with homocysteine (r = 0.531, P = 0.006; r = -0.487; P = 0.011 and r = -0.409; P = 0.034, respectively). LT-CPAP had no effect on all the OGTT-related measurements, but increased plasma total antioxidant status (+7.74%; P = 0.035) in a duration-dependent manner (r = 0.607; P < 0.001), and decreased both homocysteine (-15.2%; P = 0.002) and NT-proBNP levels (-39.3%; P = 0.002).

CONCLUSIONS

In non-obese non-diabetic OSA patients, nocturnal oxygen desaturation is strongly associated to insulin resistance. LT-CPAP does not improve glucose homeostasis nor insulin sensitivity but has a favorable effect on antioxidant capacity and cardiovascular risk biomarkers.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease, which includes coronary artery disease, stroke and congestive heart failure, is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is an elevated circulating total homocysteine level, which is associated with cardiovascular events. The impact of homocysteine-lowering interventions, given to patients in the form of vitamins B6, B9 or B12 supplements, on cardiovascular events. This is an update of a review previously published in 2009 and 2013.

OBJECTIVES

To determine whether homocysteine-lowering interventions, provided in patients with and without pre-existing cardiovascular disease are effective in preventing cardiovascular events, as well as all-cause mortality and evaluate their safety.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 1), MEDLINE (1950 to January week 5 2014), EMBASE (1980 to 2014 week 6) and LILACS (1986 to February 2014). We also searched Web of Science (1970 to 7 February 2014). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

In this second updated Cochrane Review, we identified no new randomised controlled trials. Therefore, this new version includes 12 randomised controlled trials involving 47,429 participants. In general terms, 75% (9/12) trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (1743/23,590 (7.38%) versus 1247/20,190 (6.17%); RR 1.02, 95% confidence interval (CI) 0.95 to 1.10, I(2) = 0%, high quality evidence), stroke (968/22,348 (4.33%) versus 974/18,957 (5.13%); RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%, high quality evidence) or death from any cause (2784/22,648 (12.29%) versus 2502/19,250 (10.64%); RR 1.01, 95% CI 0.96 to 1.07, I(2) = 6%, high quality evidence). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1558/18,130 (8.59%) versus 1334/14,739 (9.05%); RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%, high quality evidence).

AUTHORS' CONCLUSIONS

This second update of this Cochrane Review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence to suggest that homocysteine-lowering interventions are associated with an increased risk of cancer.

Subclinical carotid artery disease and plasma homocysteine levels in patients with hypertension

Information on the association between homocysteine (Hcy) levels and subclinical carotid artery disease is limited. We investigated the relationship of plasma Hcy concentration with carotid artery plaques and intima-media thickness (IMT) in patients with hypertension. In 486 essential hypertensive patients who underwent ultrasound examination of the carotid arteries, we measured plasma levels of Hcy, vitamin B12, folate, and C-reactive protein. Plaques were detected in 34% of the study patients. Plasma Hcy levels were significantly greater in hypertensive patients with evidence of carotid plaques than patients without carotid plaques. Carotid IMT progressively increased across quartiles of plasma Hcy levels. Multivariate regression showed that carotid IMT was independently related with age, blood pressure, C-reactive protein, and Hcy levels. In a logistic regression, age, blood pressure, triglyceride, and Hcy independently predicted the presence of carotid plaques. Thus, elevated plasma Hcy levels are associated with asymptomatic carotid disease in hypertensive patients suggesting a role of Hcy in the development and progression of carotid atherosclerosis in these patients.

Nutritional B vitamin deficiency alters the expression of key proteins associated with vascular smooth muscle cell proliferation and migration in the aorta of atherosclerotic apolipoprotein E null mice

Low B vitamin status is linked with human vascular disease. We employed a proteomic and biochemical approach to determine whether nutritional folate deficiency and/or hyperhomocysteinemia altered metabolic processes linked with atherosclerosis in ApoE null mice. Animals were fed either a control fat (C; 4 % w/w lard) or a high-fat [HF; 21 % w/w lard and cholesterol (0/15 % w/w)] diet with different B vitamin compositions for 16 weeks. Aorta tissue was prepared and global protein expression, B vitamin, homocysteine and lipoprotein status measured. Changes in the expression of aorta proteins were detected in response to multiple B vitamin deficiency combined with a high-fat diet (P < 0.05) and were strongly linked with lipoprotein concentrations measured directly in the aorta adventitia (P < 0.001). Pathway analysis revealed treatment effects in the aorta-related primarily to cytoskeletal organisation, smooth muscle cell adhesion and invasiveness (e.g., fibrinogen, moesin, transgelin, vimentin). Combined B vitamin deficiency induced striking quantitative changes in the expression of aorta proteins in atherosclerotic ApoE null mice. Deregulated expression of these proteins is associated with human atherosclerosis. Cellular pathways altered by B vitamin status included cytoskeletal organisation, cell differentiation and migration, oxidative stress and chronic inflammation. These findings provide new insight into the molecular mechanisms through which B vitamin deficiency may accelerate atherosclerosis.

Novel metabolic biomarkers of cardiovascular disease

Coronary heart disease (CHD) accounts for one in every six deaths in US individuals. Great advances have been made in identifying important risk factors for CHD, such as hypertension, diabetes mellitus, smoking and hypercholesterolaemia, which have led to major developments in therapy. In particular, statins represent one of the greatest successes in the prevention of CHD. While these standard risk factors are important, an obvious opportunity exists to take advantage of ongoing scientific research to better risk-stratify individuals and to identify new treatment targets. In this Review, we summarize ongoing scientific research in a number of metabolic molecules or features, including lipoproteins, homocysteine, calcium metabolism and glycaemic markers. We evaluate the current state of the research and the strength of evidence supporting each emerging biomarker. We also discuss whether the associations with CHD are strong and consistent enough to improve current risk stratification metrics, and whether these markers enhance our understanding of the underlying biology of CHD and thus point towards new treatment options.

Plasma homocysteine, dietary B vitamins, betaine, and choline and risk of peripheral artery disease

OBJECTIVE

Few studies have examined the roles of homocysteine and related nutrients in the development of peripheral artery disease (PAD). We examined the associations between plasma homocysteine, dietary B vitamins, betaine, choline, and supplemental folic acid use and incidence of PAD.

METHODS

We used two cohort studies of 72,348 women in the Nurses' Health Study (NHS, 1990-2010) and 44,504 men in the Health Professionals Follow-up Study (HPFS, 1986-2010). We measured plasma homocysteine in nested matched case-control studies of clinically recognized PAD within both cohorts, including 143 PAD cases and 424 controls within the NHS (1990-2010) and 143 PAD cases and 428 controls within the HPFS (1994-2008). We examined the association between diet and risk of incident PAD in the cohorts using a food frequency questionnaire and 790 cases of PAD over 3.1 million person-years of follow-up.

RESULTS

Higher homocysteine levels were positively associated with risk of PAD in men (adjusted IRR 2.17; 95% CI, 1.08-4.38 for tertile 3 vs. 1). There was no evidence of an association in women (adjusted IRR 1.14; 95% CI, 0.61-2.12). Similarly, higher folate intake, including supplements, was inversely associated with risk of PAD in men (adjusted HR 0.90; 95% CI, 0.82-0.98 for each 250 μg increase) but not women (HR 1.01, 95% CI, 0.88-1.15). Intakes of the other B vitamins, betaine, and choline were not consistently associated with risk of PAD in men or women.

CONCLUSION

Homocysteine levels were positively associated and dietary folate intake was inversely associated with risk of PAD in men but not in women.

Enhancing the health-promoting effects of tomato fruit for biofortified food

Consumption of tomato fruits, like those of many other plant species that are part of the human diet, is considered to be associated with several positive effects on health. Indeed, tomato fruits are an important source of bioactive compounds with known beneficial effects including vitamins, antioxidants, and anticancer substances. In particular, antioxidant metabolites are a group of vitamins, carotenoids, phenolic compounds, and phenolic acid that can provide effective protection by neutralizing free radicals, which are unstable molecules linked to the development of a number of degenerative diseases and conditions. In this review, we will summarize the recent progress on tomatoes nutritional importance and mechanisms of action of different phytochemicals against inflammation processes and prevention of chronic noncommunicable diseases (e.g., obesity, diabetes, coronary heart disease, and hypertension). In addition, we will summarize the significant progress recently made to improve the nutritional quality of tomato fruits through metabolic engineering and/or breeding.

Homocysteine levels and treatment effect in the PROspective Study of Pravastatin in the Elderly at Risk

Objectives

To assess the effect of preventive pravastatin treatment on coronary heart disease (CHD) morbidity and mortality in older persons at risk for cardiovascular disease (CVD), stratified according to plasma levels of homocysteine.

Design

A post hoc subanalysis in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), started in 1997, which is a double-blind, randomized, placebo-controlled trial with a mean follow-up of 3.2 years.

Setting

Primary care setting in two of the three PROSPER study sites (Netherlands and Scotland).

Participants

Individuals (n = 3,522, aged 70–82, 1,765 male) with a history of or risk factors for CVD were ranked in three groups depending on baseline homocysteine level, sex, and study site.

Intervention

Pravastatin (40 mg) versus placebo.

Measurements

Fatal and nonfatal CHD and mortality.

Results

In the placebo group, participants with a high homocysteine level (n = 588) had a 1.8 higher risk (95% confidence interval (CI) = 1.2–2.5, P = .001) of fatal and nonfatal CHD than those with a low homocysteine level (n = 597). The absolute risk reduction in fatal and nonfatal CHD with pravastatin treatment was 1.6% (95% CI = −1.6 to 4.7%) in the low homocysteine group and 6.7% (95% CI = 2.7–10.7%) in the high homocysteine group (difference 5.2%, 95% CI = 0.11–10.3, P = .046). Therefore, the number needed to treat (NNT) with pravastatin for 3.2 years for benefit related to fatal and nonfatal CHD events was 14.8 (95% CI = 9.3–36.6) for high homocysteine and 64.5 (95% CI = 21.4–∞) for low homocysteine.

Conclusion

In older persons at risk of CVD, those with high homocysteine are at highest risk for fatal and nonfatal CHD. With pravastatin treatment, this group has the highest absolute risk reduction and the lowest NNT to prevent fatal and nonfatal CHD.

Homocysteine-lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease (including coronary artery disease, stroke and congestive heart failure), is a leading cause of death worldwide. Homocysteine is an amino acid with biological functions in methionine metabolism. A postulated risk factor is elevated circulating total homocysteine levels, which are associated with cardiovascular events. This is an update of a review previously published in 2009.

OBJECTIVES

To assess the clinical effectiveness of homocysteine-lowering interventions in people with or without pre-existing cardiovascular disease.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (2012, Issue 2), MEDLINE (1950 to Feb week 2 2012), EMBASE (1980 to 2012 week 07), and LILACS (1986 to February 2012). We also searched ISI Web of Science (1970 to February 2012). We handsearched the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of homocysteine-lowering interventions for preventing cardiovascular events with a follow-up period of one year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We performed study selection, 'Risk of bias' assessment and data extraction in duplicate. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model.

MAIN RESULTS

In this updated systematic review, we identified four new randomised trials, resulting in a total of 12 randomised controlled trials involving 47,429 participants. In general terms, the trials had a low risk of bias. Homocysteine-lowering interventions compared with placebo did not significantly affect non-fatal or fatal myocardial infarction (pooled RR 1.02, 95% CI 0.95 to 1.10, I(2) = 0%), stroke (pooled RR 0.91, 95% CI 0.82 to 1.0, I(2) = 11%) or death by any cause (pooled RR 1.01 (95% CI 0.96 to 1.07, I(2): 6%)). Homocysteine-lowering interventions compared with placebo did not significantly affect serious adverse events (cancer) (1 RR 1.06, 95% CI 0.98 to 1.13; I(2) = 0%).

AUTHORS' CONCLUSIONS

This updated Cochrane review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence suggesting that homocysteine-lowering interventions are associated with an increased risk of cancer.

Common variant in FUT2 gene is associated with levels of vitamin B(12) in Indian population

Vitamin B(12) is an essential micronutrient synthesized by microorganisms. Mammals including humans have evolved ways for transport and absorption of this vitamin. Deficiency of vitamin B(12) (either due to low intake or polymorphism in genes involved in absorption and intracellular transport of this vitamin) has been associated with various complex diseases. Genome-wide association studies have recently identified several common single nucleotide polymorphisms (SNPs) in fucosyl transferase 2 gene (FUT2) to be associated with levels of vitamin B(12)-the strongest association was with a non-synonymous SNP rs602662 in this gene. In the present study, we attempted to replicate the association of this SNP (rs602662) in an Indian population since a significant proportion has been reported to have low levels of vitamin B(12) in this population. A total of 1146 individuals were genotyped for this SNP using a single base extension method and association with levels of vitamin B(12) was assessed in these individuals. Regression analysis was performed to analyze the association considering various confounding factors like for age, sex, diet, hypertension, diabetes mellitus and coronary artery disease status. We found that the SNP rs602662 was significantly associated with the levels of vitamin B(12) (p value<0.0001). We also found that individuals adhering to a vegetarian diet with GG (homozygous major genotype) have significantly lower levels of vitamin B(12) in these individuals. Thus, our study reveals that vegetarian diet along with polymorphism in the FUT2 gene may contribute significantly to the high prevalence of vitamin B(12) deficiency in India.

Hydrogen sulfide in the mammalian cardiovascular system

For more than a century, hydrogen sulfide (H(2)S) has been regarded as a toxic gas. This review surveys the growing recognition of the role of H(2)S as an endogenous signaling molecule in mammals, with emphasis on its physiological and pathological pathways in the cardiovascular system. In biological fluids, H(2)S gas is a weak acid that exists as about 15% H(2)S, 85% HS(-), and a trace of S(2-). Here, we use "H(2)S" to refer to this mixture. H(2)S has been found to influence heart contractile functions and may serve as a cardioprotectant for treating ischemic heart diseases and heart failure. Alterations of the endogenous H(2)S level have been found in animal models with various pathological conditions such as myocardial ischemia, spontaneous hypertension, and hypoxic pulmonary hypertension. In the vascular system, H(2)S exerts biphasic regulation of a vascular tone with varying effects based on its concentration and in the presence of nitric oxide. Over the past decade, several H(2)S-releasing compounds (NaHS, Na(2)S, GYY4137, etc.) have been utilized to test the effect of exogenous H(2)S under different physiological and pathological situations in vivo and in vitro. H(2)S has been found to promote angiogenesis and to protect against atherosclerosis and hypertension, while excess H(2)S may promote inflammation in septic or hemorrhagic shock. H(2)S-releasing compounds and inhibitors of H(2)S synthesis hold promise in alleviating specific disease conditions. This comprehensive review covers in detail the effects of H(2)S on the cardiovascular system, especially in disease situations, and also the various underlying mechanisms.

Nutritional B vitamin deficiency disrupts lipid metabolism causing accumulation of proatherogenic lipoproteins in the aorta adventitia of ApoE null mice

SCOPE

Cardiovascular disease is the major cause of death in the world. Low dietary folate, elevated homocysteine, and high circulating cholesterol are risk factors.

METHODS AND RESULTS

We investigated whether folate and/or B vitamin deficiency would change lipoprotein and fatty acid metabolism and lipid accumulation in the aorta adventitia of ApoE null mice. Mice (n = 10 per group) were fed a control (C; 4%) or high saturated fat (HF; 21%), and high cholesterol (0.15%) diet for 16 weeks. Folate (F-) or folate, B6 and B12 deficiency (F-B-) were imposed on these diets. Feeding a HF diet increased plasma and liver total cholesterol and HDL cholesterol (two- to threefold; p < 0.05). Total cholesterol increased (twofold; p < 0.05) in aorta adventitial lipid in response to HF. Feeding a diet depleted of folate and B vitamins (F-B-) significantly increased cholesterol accumulation in both liver and aorta adventitial lipid (approximately 50-70%; p < 0.05). Moreover, the proportions of fatty acids in hepatic and adventitial lipid was significantly changed by B vitamin depletion, measured as an increase in saturated fatty acids (approximately 15%) and a decrease (approximately 11%) in monounsaturated fatty acids (p < 0.05).

CONCLUSION

B vitamin deficiency perturbs lipid metabolism in ApoE null mice, causing accumulation of proatherogenic cholesterol and fatty acids in the aorta adventitia.

Homocysteine upregulates soluble epoxide hydrolase in vascular endothelium in vitro and in vivo

RATIONALE

Hyperhomocysteinemia is a risk factor of atherogenesis. Soluble epoxide hydrolase (sEH) is a major enzyme that hydrolyzes epoxyeicosatrienoic acids and attenuates their cardiovascular protective effects. Whether homocysteine (Hcy) regulates sEH and the underlying mechanism remains elusive.

OBJECTIVE

To elucidate the mechanism by which Hcy regulates sEH expression and endothelial activation in vitro and in vivo.

METHODS AND RESULTS

Hcy treatment in cultured human endothelial cells dose-dependently and time-dependently upregulated sEH mRNA and protein. Hcy increased the expression of adhesion molecules, which was markedly reversed by inhibiting sEH activity. Hcy-induced sEH upregulation is associated with activation of activating transcription factor-6 (ATF6). Bioinformatics analysis revealed a putative ATF6-binding motif in the promoter region of the sEH gene, which was found at a methylation site. Site-directed mutagenesis and chromatin immunoprecipitation assays demonstrated that Hcy treatment or ATF6 overexpression promoted ATF6 binding to the promoter of sEH and increased its activity. Results of methylation-specific polymerase chain reaction revealed that the ATF6 binding site on the sEH promoter was partially methylated and was demethylated with Hcy. SiRNA knockdown of ATF6α or SP1 blocked and ATF6 overexpression and DNA methyltransferase inhibitor mimicked the effect of homocysteine on sEH upregulation. In vivo, immunofluorescence assay revealed elevated expression of sEH and adhesion molecules in the aortic intima of mice with mild hyperhomocysteinemia, which was attenuated by sEH deletion or inhibition.

CONCLUSION

ATF6 activation and DNA demethylation may coordinately contribute to Hcy-induced sEH expression and endothelial activation. Inhibition of sEH may be a therapeutic approach for treating Hcy-induced cardiovascular diseases.

Do cysteine residues regulate transient receptor potential canonical type 6 channel protein expression?

The regulation of calcium influx through transient receptor potential canonical type 6 (TRPC6) channel is mandatory for the activity of human monocytes. We submit the first evidence that cysteine residues of homocysteine (HC) or acetylcysteine (ACC) affect TRPC6 expression in human monocytes. We observed that patients with chronic renal failure had significantly elevated HC levels and TRPC6 mRNA expression levels in monocytes compared with control subjects. We further observed that administration of HC or ACC significantly increased TRPC6 channel protein expression compared with control conditions. We, therefore, hypothesize that cysteine residues increase TRPC6 channel protein expression in humans.

A sulfur amino acid-free meal increases plasma lipids in humans

The content of sulfur amino acid (SAA) in a meal affects postprandial plasma cysteine concentrations and the redox potential of cysteine/cystine. Because such changes can affect enzyme, transporter, and receptor activities, meal content of SAA could have unrecognized effects on metabolism during the postprandial period. This pilot study used proton NMR ((1)H-NMR) spectroscopy of human plasma to test the hypothesis that dietary SAA content changes macronutrient metabolism. Healthy participants (18-36 y, 5 males and 3 females) were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (depletion), and then fed isoenergetic, isonitrogenous meals containing 56 mg·kg(-1)·d(-1) SAA for 4.5 d (repletion). On the first and last day of consuming the chemically defined meals, a morning meal containing 60% of the daily food intake was given and plasma samples were collected over an 8-h postprandial time course for characterization of metabolic changes by (1)H-NMR spectroscopy. SAA-free food increased peak intensity in the plasma (1)H-NMR spectra in the postprandial period. Orthogonal signal correction/partial least squares-discriminant analysis showed changes in signals associated with lipids, some amino acids, and lactate, with notable increases in plasma lipid signals (TG, unsaturated lipid, cholesterol). Conventional lipid analyses confirmed higher plasma TG and showed an increase in plasma concentration of the lipoprotein lipase inhibitor, apoC-III. The results show that plasma (1)H-NMR spectra can provide useful macronutrient profiling following a meal challenge protocol and that a single meal with imbalanced SAA content alters postprandial lipid metabolism.

Association of body mass index and alcohol intake with hypertension subtypes among HAN Chinese

Obesity and excessive drinking are major risk factors for development of hypertension. We aimed to explore association of body mass index (BMI) and alcohol intake with isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and combined systolic/diastolic hypertension (SDH) among Shandong Shengli Oil field workers. A total of 26,681 subjects were cross-sectionally analyzed. Statistical calculations included polytomous logistic regression and interaction analysis. After assigning normotensives as a reference, the odds of being ISH decreased by 4% for moderate drinkers, whereas that of being IDH and SDH increased significantly by 1.50 and 1.15 folds (P < 0.001). The odds for heavy drinkers of being ISH, IDH, and SDH increased by 1.38, 2.41, and 2.25 folds, respectively (P < 0.001). For BMI, the odds of being ISH, IDH, and SDH increased in a dose-response manner (P < 0.001). For patients with BMI of [23, 25), [25, 27), [27, 30) and ≥ 30 kg/m(2), the odds (95% confidence interval (CI)) of being SDH increased significantly by 2.28 (2.07-2.50), 3.22 (2.93-3.55), 5.44 (4.93-6.01), and 8.45 (7.31-9.77) folds, respectively. Interaction analysis indicated that BMI and alcohol intake were interactively associated with ISH (P ≤ 0.045) rather than IDH (P ≥ 0.161). Our results demonstrated that BMI and alcohol intake interactively influenced systolic hypertension, especially for overweight and obese patients.

Nutraceuticals and headache: the biological basis

Nutrition must affect the structure and functioning of the brain. Since the brain has very high metabolic activity, what we consume throughout the day is likely to dramatically influence both its structure and moment to moment function. It follows that nutritional approaches to all neurological disorders are being researched and entering medical practice, while nutraceutical use is a mainstay of public habits. This review discusses the biological basis for non-conventional or non-mainstream approaches to the treatment of migraine. This requires at least limited discussion of current migraine pathophysiologic theory. How nutrients and other chemicals and approaches are mechanistically involved within migraine pathways is the focus of this article. The nutraceuticals reviewed in detail are: magnesium, riboflavin, coenzyme Q10, petasites, and feverfew with additional comments on marijuana and oxygen/hyperbaric oxygen. This article reviews the science when known related to the potential genetic susceptibility and sensitivity to these treatments. As we know, the basic science in this field is very preliminary, so whether to combine approaches and presumably mechanisms or use them alone or with or without conventional therapies is far from clear. Nonetheless, as more patients and providers participate in patient-centered approaches to care, knowledge of the science underpinning nutritional, nutraceutical, and complementary approaches to treatment for migraine will certainly benefit this interaction.

Identification of differentially expressed proteins in blood plasma of control and cigarette smoke-exposed mice by 2-D DIGE/MS

Cigarette smoke exposure is known to induce obstructive lung disease and several cardiovascular disease states in humans and also in animal models. Smoking leads to oxidative stress and inflammation that are important in triggering pulmonary and cardiovascular disease. The objective of the current study was to quantify differences in expression levels of plasma proteins of cigarette smoke -exposed and control mice, at the time of disease onset, and identify these proteins for use as potential biomarkers of the onset of smoking-induced disease. We utilized 2-D DIGE/MS to characterize these proteomic changes. 2-D DIGE of plasma samples identified 11 differentially expressed proteins in cigarette smoke -exposed mice. From these 11 proteins, 9 were downregulated and 2 were upregulated. The proteins identified are involved in vascular function, coagulation, metabolism and immune function. Among these, the alterations in fibrinogen (2.2-fold decrease), α-1-antitrypsin (1.8-fold increase) and arginase (4.5-fold decrease) are of particular interest since these have been directly linked to cardiovascular and lung pathology. Differences in expression levels of these proteins were also confirmed by immunoblotting. Thus, we observe that chronic cigarette smoke exposure in mice leads to prominent changes in the protein expression profile of blood plasma and these changes in turn can potentially serve as markers predictive of the onset and progression of cardiovascular and pulmonary disease.

The annexin A2 system and vascular homeostasis

Optimal fibrin balance requires precisely controlled plasmin generation on the surface of endothelial cells, which line the blood vessel wall. As a co-receptor for plasminogen and tissue plasminogen activator (tPA), which are key factors in plasmin generation, the annexin A2 (A2) complex promotes vascular fibrinolysis. The intracellular A2 complex is a heterotetramer of two A2 monomers and two copies of the associated protein, p11. In response to endothelial cell activation, A2 is phosphorylated by src-kinase, and translocated to the cell surface in a highly regulated manner. Over-expression of A2 is seen in acute promyelocytic leukemia during the early hemorrhagic phase, while high titer antibodies to A2, as in antiphospholipid syndrome or cerebral venous thrombosis, are associated with thrombosis. In experimental hyperhomocysteinemia, moreover, derivatization of A2 by homocysteine leads to intravascular fibrin accumulation and dysangiogenesis, features that phenocopy the Anxa2(-/-) mouse. Exogenous A2 may also offer a novel therapeutic approach to ischemic thrombotic stroke, as administration of A2 in conjunction with conventional tPA-based thrombolytic therapy improved outcome in an animal model. Here, we discuss the role of the A2 system in vascular homeostasis, the molecular interactions that regulate its profibrinolytic activity, and its potential role in the pathogenesis and treatment of vascular disease.

Differential effects of nutritional folic acid deficiency and moderate hyperhomocysteinemia on aortic plaque formation and genome-wide DNA methylation in vascular tissue from ApoE-/- mice

Low folate intake is associated with vascular disease. Causality has been attributed to hyperhomocysteinemia. However, human intervention trials have failed to show the benefit of homocysteine-lowering therapies. Alternatively, low folate may promote vascular disease by deregulating DNA methylation. We investigated whether folate could alter DNA methylation and atherosclerosis in ApoE null mice. Mice were fed one of six diets (n = 20 per group) for 16 weeks. Basal diets were either control (C; 4% lard) or high fat (HF; 21% lard and cholesterol, 0.15%) with different B-vitamin compositions: (1) folic acid and B-vitamin replete, (2) folic acid deficient (-F), (3) folic acid, B6 and B12 deficient (-F-B). -F diets decreased plasma (up to 85%; P < 0.05), whole blood (up to 70%; P < 0.05), and liver folate (up to 65%; P < 0.05) and hepatic SAM/SAH (up to 80%; P < 0.05). -F-B diets reduced plasma (up to 76%; P < 0.05), whole blood (up to 72%; P < 0.05), and liver B12 (up to 39%; P < 0.05) and hepatic SAM/SAH (up to 90%; P < 0.05). -F increased homocysteine 2-fold, while -F-B increased homocysteine 3.6- and 6.8-fold in the C and HF groups (P < 0.05). Plaque formation was increased 2-fold (P < 0.0001) in mice fed a HF diet. Feeding a HF-F diet increased lesion formation by 17% (P < 0.05). There was no change in 5-methyldeoxycytidine in liver or vascular tissue (aorta, periadventitial tissue and heart). These data suggest that atherogenesis is not associated with genome-wide epigenetic changes in this animal model.

Epigenetic modifications and human pathologies: cancer and CVD

Epigenetic changes are inherited alterations in DNA that affect gene expression and function without altering the DNA sequence. DNA methylation is one epigenetic process implicated in human disease that is influenced by diet. DNA methylation involves addition of a 1-C moiety to cytosine groups in DNA. Methylated genes are not transcribed or are transcribed at a reduced rate. Global under-methylation (hypomethylation) and site-specific over-methylation (hypermethylation) are common features of human tumours. DNA hypomethylation, leading to increased expression of specific proto-oncogenes (e.g. genes involved in proliferation or metastasis) can increase the risk of cancer as can hypermethylation and reduced expression of tumour suppressor (TS) genes (e.g. DNA repair genes). DNA methyltransferases (DNMT), together with the methyl donor S-adenosylmethionine (SAM), facilitate DNA methylation. Abnormal DNA methylation is implicated not only in the development of human cancer but also in CVD. Polyphenols, a group of phytochemicals consumed in significant amounts in the human diet, effect risk of cancer. Flavonoids from tea, soft fruits and soya are potent inhibitors of DNMT in vitro, capable of reversing hypermethylation and reactivating TS genes. Folates, a group of water-soluble B vitamins found in high concentration in green leafy vegetables, regulate DNA methylation through their ability to generate SAM. People who habitually consume the lowest level of folate or with the lowest blood folate concentrations have a significantly increased risk of developing several cancers and CVD. This review describes how flavonoids and folates in the human diet alter DNA methylation and may modify the risk of human colon cancer and CVD.

Meta-analysis of folic acid supplementation trials on risk of cardiovascular disease and risk interaction with baseline homocysteine levels

Experimental models and observational studies suggest that homocysteine-lowering therapy with folic acid (FA) may prevent cardiovascular disease (CVD). However, FA also stimulates cell proliferation and might promote progression of atherosclerosis. Our objectives were to perform a meta-analysis of FA supplementation trials on CVD events and to explore a potential interaction between FA supplementation and baseline homocysteine levels on CVD events. We searched MEDLINE for randomized controlled trials of FA supplementation to prevent CVD events (January 1966 to July 2009) and performed meta-analyses using random effects models. For trials that reported responses to FA supplementation stratified by baseline levels of homocysteine, we pooled within-trial estimates of differences in log-relative risks by baseline homocysteine levels using a random effects model. Overall, FA supplementation did not affect primary cardiovascular clinical end points (relative risk 1.02, 95% confidence interval [CI] 0.93 to 1.13, p = 0.66) or stroke (relative risk 0.95, 95% CI 0.84 to 1.08, p = 0.43). However, in trials that reported analyses stratified by baseline homocysteine, effect of FA supplementation differed by strata of baseline homocysteine (p for interaction = 0.030). Specifically, risks of primary clinical CVD events comparing FA supplementation to control were 1.06 (95% CI 1.00 to 1.13) in strata with mean baseline homocysteine levels >12 mumol/L and 0.94 (95% CI 0.86 to 1.03) in strata with baseline homocysteine levels <12 micromol/L. In conclusion, FA had no effect on CVD or stroke. However, analysis of within-trial results stratified by baseline homocysteine suggests potential harm in those with high homocysteine at baseline. This interaction may have important implications for recommendations of FA supplement use. In the meantime, FA supplementation should not be recommended as a means to prevent or treat CVD or stroke.

Hydrogen sulfide: regulatory role on blood pressure in hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is a metabolic disorder marked by an excess amount of the amino acid homocysteine (Hcy) in the blood stream. Hcy is a H(2)S precursor-formed from the metabolism of methionine. Elevated Hcy levels have been associated with higher blood pressure. However, the precise contribution of H(2)S to blood pressure in HHcy is not known. In the current study, we have examined a novel link between H(2)S, blood pressure and HHcy. Male Sprague-Dawley rats were injected with PAG, NaHS, L-NAME+PAG and saline. HHcy condition was induced by providing methionine (1 g/kg) in drinking water for 8 weeks. After 8 weeks, plasma Hcy and H(2)S were measured. The treated rats were anaesthetized with a mixture of ketamine hydrochloride and medetomidine. Blood pressures were measured by intra-carotid artery catheterization and to further investigate the immediate effect of NO and H(2)S, exogenous drugs namely NaHS, SNP, Ach and NA were administered. Plasma Hcy levels were higher in HHcy groups and this group exhibited hypertension. We observed high blood pressure at low levels of H(2)S and vice versa. Endogenous H(2)S in HHcy condition facilitated a mild decrease in MAP (Mean Arterial Pressure). Exogenous SNP (NO donor) showed a greater pressure decrease in HHcy group. The underlying mechanism is yet to be exploited. High levels of Hcy play an important role in the pathogenesis of hypertension. The results suggest that both endogenous and exogenous H(2)S may play a vital role in regulating blood pressure in HHcy.

Homocysteine inhibits neoangiogenesis in mice through blockade of annexin A2-dependent fibrinolysis

When plasma levels of homocysteine (HC), a thiol amino acid formed upon methionine demethylation, exceed 12 muM, individuals are at increased risk of developing large vessel atherothrombosis and small vessel dysfunction. The annexin A2 complex (termed "A2") is the cell surface coreceptor for plasminogen and TPA and accelerates the catalytic activation of plasmin, the major fibrinolytic agent in mammals. We previously showed that HC prevents A2-mediated, TPA-dependent activation of plasminogen in vitro by disulfide derivatization of the "tail" domain of A2. We also demonstrated that fibrinolysis and angiogenesis are severely impaired in A2-deficient mice. We now report here that, although hyperhomocysteinemic mice had a normal coagulation profile and normal platelet function, fibrin accumulated in their tissues due to reduced perivascular fibrinolytic activity and angiogenesis was impaired. A2 isolated from hyperhomocysteinemic mice failed to fully support TPA-dependent plasmin activation. However, infusion of hyperhomocysteinemic mice with fresh recombinant A2, which localized to neoangiogenic endothelial cells, resulted in normalization of angiogenesis and disappearance of peri- and intravascular fibrin. We therefore conclude that hyperhomocysteinemia impairs postnatal angiogenesis by derivatizing A2, preventing perivascular fibrinolysis, and inhibiting directed endothelial cell migration. These findings provide a mechanistic explanation for microvascular dysfunction and macrovascular occlusion in individuals with hyperhomocysteinemia.

Homocysteine lowering interventions for preventing cardiovascular events

BACKGROUND

Cardiovascular disease such as coronary artery disease, stroke and congestive heart failure, is a leading cause of death worldwide. A postulated risk factor is elevated circulating total homocysteine (tHcy) levels which is influenced mainly by blood levels of cyanocobalamin (vitamin B12), folic acid (vitamin B9) and pyridoxine (vitamin B6). There is uncertainty regarding the strength of association between tHcy and the risk of cardiovascular disease.

OBJECTIVES

To assess the clinical effectiveness of homocysteine-lowering interventions (HLI) in people with or without pre-existing cardiovascular disease.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (issue 3 2008), MEDLINE (1950 to August 2008), EMBASE (1988 to August 2008), and LILACS (1982 to September 2, 2008). We also searched in Allied and Complementary Medicine (AMED; 1985 to August 2008), ISI Web of Science (1993 to August 2008), and the Cochrane Stroke Group Specialised Register (April 2007). We hand searched pertinent journals and the reference lists of included papers. We also contacted researchers in the field. There was no language restriction in the search.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) assessing the effects of HLI for preventing cardiovascular events with a follow-up period of 1 year or longer. We considered myocardial infarction and stroke as the primary outcomes. We excluded studies in patients with end-stage renal disease.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model to synthesise the findings.

MAIN RESULTS

We included eight RCTs involving 24,210 participants with a low risk of bias in general terms. HLI did not reduce the risk of non-fatal or fatal myocardial infarction, stroke, or death by any cause (pooled RR 1.03, 95% CI 0.94 to 1.13, I(2) = 0%; pooled RR 0.89, 95% CI 0.73 to 1.08, I(2) = 15%); and pooled RR 1.00 (95% CI 0.92 to 1.09, I(2): 0%), respectively.

AUTHORS' CONCLUSIONS

Results from available published trials suggest that there is no evidence to support the use of HLI to prevent cardiovascular events.

Potential influences of complementary therapy on motor and non-motor complications in Parkinson's disease

Nearly two-thirds of patients with Parkinson's disease (PD) use vitamins or nutritional supplements, and many more may use other complementary therapies, yet <50% of patients have discussed the use of these complementary therapies with a healthcare professional. Physicians should be aware of the complementary therapies their patients with PD are using, and the possible effects of these therapies on motor and non-motor symptoms. Complementary therapies, such as altered diet, dietary supplements, vitamin therapy, herbal supplements, caffeine, nicotine, exercise, physical therapy, massage therapy, melatonin, bright-light therapy and acupuncture, may all influence the symptoms of PD and/or the effectiveness of dopaminergic therapy. Preliminary evidence suggests complementary therapy also may influence non-motor symptoms of PD, such as respiratory disorders, gastrointestinal disorders, mood disorders, sleep and orthostatic hypotension. Whenever possible, clinicians should ensure that complementary therapy is used appropriately in PD patients without reducing the benefits of dopaminergic therapy.

Genome-wide association study of vitamin B6, vitamin B12, folate, and homocysteine blood concentrations

The B vitamins are components of one-carbon metabolism (OCM) that contribute to DNA synthesis and methylation. Homocysteine, a by-product of OCM, has been associated with coronary heart disease, stroke and neurological disease. To investigate genetic factors that affect circulating vitamin B6, vitamin B12, folate and homocysteine, a genome-wide association analysis was conducted in the InCHIANTI (N = 1175), SardiNIA (N = 1115), and BLSA (N = 640) studies. The top loci were replicated in an independent sample of 687 participants in the Progetto Nutrizione study. Polymorphisms in the ALPL gene (rs4654748, p = 8.30 x 10(-18)) were associated with vitamin B6 and FUT2 (rs602662, [corrected] p = 2.83 x 10(-20)) with vitamin B12 serum levels. The association of MTHFR, a gene consistently associated with homocysteine, was confirmed in this meta-analysis. The ALPL gene likely influences the catabolism of vitamin B6 while FUT2 interferes with absorption of vitamin B12. These findings highlight mechanisms that affect vitamin B6, vitamin B12 and homocysteine serum levels.