MTHFR 677C → T genotype modulates the effect of a 5-year supplementation with B-vitamins on homocysteine concentration: The SU.FOL.OM3 randomized controlled trial.

AIMS: To study how MTHFR 677C→T genotype modulates the effect of supplementation with B-vitamins on total homocysteine (tHcy) and B-vitamin concentrations. METHODS: 2381 patients with a personal history of cardiovascular disease were randomly assigned to one of four groups: 1) B-vitamins alone (560 µg of 5-methyl-THF, 3 mg of vitamin B6 and 20 µg of vitamin B12), 2) n-3 fatty acids alone (600 mg of EPA and DHA in a 2:1 ratio), 3) B-vitamins and n-3 fatty acids, and 4) placebo. Participants were followed up for 4.7 years. At baseline and annually thereafter, biological parameters were assessed. Multivariate and linear mixed models were fit to study the interaction between B-vitamins and MTHFR genotype. RESULTS: Among supplemented participants, concentrations of all three B-vitamins increased during the first year (all p<0.0001) across MTHFR genotype categories. tHcy decreased by 26.3% during the first year (p<0.0001), then steadily increased throughout the 5 years (ptrend<0.001). However, at the end of follow-up, that increase was smaller among TT than among CT or CC subjects (pinteraction<0.02). At baseline, the difference in tHcy concentrations between TT homozygous and CC homozygous subjects was 2.33 µmol/l (p<0.001). After 5 years, that difference was reduced to 1.06 µmol/l and remained statistically significant (p<0.001). CONCLUSION: Participants with the TT genotype exhibited a lower 5-year decrease in tHcy concentrations following a B-vitamin supplementation than did participants with the CC or CT genotype. CLINICAL TRIAL REGISTRATION: Current Controlled Trials # ISRCTN41926726.

Increased Symmetric Dimethylarginine Level Is Associated with Worse Hospital Outcomes through Altered Left Ventricular Ejection Fraction in Patients with Acute Myocardial Infarction.

OBJECTIVES: We aimed to investigate whether SDMA- symmetric dimethylarginine -the symmetrical stereoisomer of ADMA- might be a marker of left ventricular function in AMI. BACKGROUND: Asymmetric dimethylarginine (ADMA) has been implicated in the prognosis after acute myocardial infarction (AMI) and heart failure (HF). METHODS: Cross sectional prospective study from 487 consecutive patients hospitalized <24 hours after AMI. Patients with HF on admission were excluded. Serum levels of ADMA, SDMA and L-arginine were determined using HPLC. Glomerular filtration rate (eGFR) was estimated based on creatinine levels. Outcomes were in-hospital severe HF, as defined by Killip class >2, and death. RESULTS: Patients were analysed based on SDMA tertiles. Sex, diabetes, dyslipidemia, and prior MI were similar for all tertiles. In contrast, age and hypertension increased across the tertiles (p<0.001). From the first to the last tertile, GRACE risk score was elevated while LVEF and eGFR was reduced. The rate of severe HF and death were gradually increased across the SDMA tertiles (from 0.6% to 7.4%, p = 0.006 and from 0.6% to 5.0%, p = 0.034, respectively). Backward logistic multivariate analysis showed that SDMA was an independent estimate of developing severe HF, even when adjusted for confounding (OR(95%CI): 8.2(3.0-22.5), p<0.001). Further, SDMA was associated with mortality, even after adjustment for GRACE risk score (OR(95%CI): 4.56(1.34-15.52), p = 0.015). CONCLUSIONS: Our study showed for the first time that SDMA is associated with hospital outcomes, through altered LVEF and may have biological activity beyond renal function.

Association between serum concentration of vitamin D and 1-year mortality in stroke patients.

BACKGROUND: The prevalence of 25-hydroxyvitamin D [25(OH)D] deficiency is high in patients presenting with an acute stroke, and it may be associated with greater clinical severity and a poor early functional prognosis. However, no data about its impact on long-term prognosis is available. In this study, we aimed to assess the association between 25(OH)D levels and 1-year mortality in stroke patients. METHODS: From February to December 2010, 382 Caucasian stroke patients admitted to the Department of Neurology of the University Hospital of Dijon, France, were enrolled prospectively. Demographics and clinical information including stroke severity assessed using the National Institutes of Health Stroke Scale score were collected. The serum concentration of 25(OH)D was measured at baseline. Multivariable Cox regression models were used to evaluate the association between 1-year all-cause mortality and serum 25(OH)D levels treated as either a log-transformed continuous variable or dichotomized (<25.7 and ≥25.7 nmol/l) at the first tertile of their distribution. RESULTS: Of the 382 stroke patients included, 63 (16.5%) had died at 1 year. The mean 25(OH)D level was lower in these patients (32.3 ± 22.0 vs. 44.6 ± 28.7 nmol/l, p < 0.001), and survival at 1 year was worse in patients in the lowest tertile of 25(OH)D levels (defined as <25.7 nmol/l); log-transformed 25(OH)D levels were inversely associated with 1-year mortality (hazard ratio, HR = 0.62; 95% confidence interval, 95% CI: 0.44-0.87; p = 0.007), and patients with 25(OH)D levels <25.7 nmol/l were at a higher risk of death at 1 year (HR = 1.95; 95% CI: 1.14-3.32; p = 0.014). In multivariable analyses, the association was no longer significant but a significant interaction was found for age, and stratified analyses by age groups showed an inverse relationship between 25(OH)D levels and 1-year mortality in patients aged <75 years [HR = 0.38; 95% CI: 0.17-0.83; p = 0.015 for log-transformed 25(OH)D levels, and HR = 3.12; 95% CI: 0.98-9.93; p = 0.054 for 25(OH)D levels <25.7 vs. >25.7 nmol/l]. CONCLUSION: A low serum 25(OH)D level at stroke onset may be associated with higher mortality at 1 year in patients <75 years old. Further studies are needed to confirm these findings and to determine whether vitamin D supplementation could improve survival in stroke patients.

Influence of lipolysis and fatty acid availability on fuel selection during exercise

The aim of the present study was to investigate the influence of substrate availability on fuel selection during exercise. Eight endurance-trained male cyclists performed 90-min exercise at 70 % of their maximal oxygen uptake in a cross-over design, either in rested condition (CON) or the day after 2-h exercise practised at 70 % of maximal oxygen uptake (EX). Subjects were given a sucrose load (0.75 g kg−1 body weight) 45 min after the beginning of the 90-min exercise test. Lipolysis was measured in subcutaneous abdominal adipose tissue (SCAT) by microdialysis and substrate oxidation by indirect calorimetry. Lipid oxidation increased during exercise and tended to decrease during sucrose ingestion in both conditions. Lipid oxidation was higher during the whole experimental period in the EX group (p = 0.004). Interestingly, fuel selection, assessed by the change in respiratory exchange ratio (RER), was increased in the EX session (p = 0.002). This was paralleled by a higher rate of SCAT lipolysis reflected by dialysate glycerol, plasma glycerol, and fatty acids (FA) levels (p < 0.001). Of note, we observed a significant relationship between whole-body fat oxidation and dialysate glycerol in both sessions (r 2 = 0.33, p = 0.02). In conclusion, this study highlights the limiting role of lipolysis and plasma FA availability to whole-body fat oxidation during exercise in endurance-trained subjects. This study shows that adipose tissue lipolysis is a determinant of fuel selection during exercise in healthy subjects

Agreement of seven 25-hydroxy vitamin D3 immunoassays and three high performance liquid chromatography methods with liquid chromatography tandem mass spectrometry.

BACKGROUND: Several recent studies have shown some discrepancies between 25-hydroxyvitamin D [25(OH)D] assay methods, despite some improvement in the past few years. The accuracy of 25(OH)D assay methods is still a real challenge for clinical laboratories. The aim of this study was to assess the agreement between a large panel of routine assays and a two-dimensional liquid chromatography/tandem mass spectrometry (2D LC-MS/MS) method, selected as the reference method. METHODS: Forty-nine human plasma samples with only endogenous 25(OH)D3 were analyzed with 11 different methods, especially with three LC-UV methods that differed in the extraction step. Seven routine immunoassays were also tested: two manual (RIA and EIA from IDS) and five fully-automated methods. The results of the 25(OH)D3 assays were compared with those of the 2D LC-MS/MS method using weighted Deming regression analysis, Bland-Altman plots and concordance correlation coefficient (CCC). The ability of these methods to properly classify patients was evaluated by sorting results depending on vitamin D status. RESULTS: The CCC was >0.90 for the three LC-UV methods and for most of the automated IA, meaning substantial agreement with 2D LC-MS/MS results. The ability to properly classify patients according to their vitamin D status was overall satisfactory for most of the methods tested (concordance >90%). CONCLUSIONS: The immunoassays available on Liaison, Isys, Architect and Elecsys, together with our in-house LC-UV method preceded by an SLE step met the minimum requirements for the assessment of vitamin D status in clinical laboratories.

Arginine and nitric oxide synthase: regulatory mechanisms and cardiovascular aspects.

L-Arginine (L-Arg) is a conditionally essential amino acid in the human diet. The most common dietary sources of L-Arg are meat, poultry and fish. L-Arg is the precursor for the synthesis of nitric oxide (NO); a key signaling molecule via NO synthase (NOS). Endogenous NOS inhibitors such as asymmetric-dimethyl-L-Arg inhibit NO synthesis in vivo by competing with L-Arg at the active site of NOS. In addition, NOS possesses the ability to be "uncoupled" to produce superoxide anion instead of NO. Reduced NO bioavailability may play an essential role in cardiovascular pathologies and metabolic diseases. L-Arg deficiency syndromes in humans involve endothelial inflammation and immune dysfunctions. Exogenous administration of L-Arg restores NO bioavailability, but it has not been possible to demonstrate, that L-Arg supplementation improved endothelial function in cardiovascular disease such as heart failure or hypertension. L-Arg supplementation may be a novel therapy for obesity and metabolic syndrome. The utility of l-Arg supplementation in the treatment of L-Arg deficiency syndromes remains to be established. Clinical trials need to continue to determine the optimal concentrations and combinations of L-Arg, with other protective compounds such as tetrahydrobiopterin (BH4 ), and antioxidants to combat oxidative stress that drives down NO production in humans.

Influence of lipolysis and fatty acid availability on fuel selection during exercise.

The aim of the present study was to investigate the influence of substrate availability on fuel selection during exercise. Eight endurance-trained male cyclists performed 90-min exercise at 70% of their maximal oxygen uptake in a cross-over design, either in rested condition (CON) or the day after 2-h exercise practised at 70% of maximal oxygen uptake (EX). Subjects were given a sucrose load (0.75 g kg(-1) body weight) 45 min after the beginning of the 90-min exercise test. Lipolysis was measured in subcutaneous abdominal adipose tissue (SCAT) by microdialysis and substrate oxidation by indirect calorimetry. Lipid oxidation increased during exercise and tended to decrease during sucrose ingestion in both conditions. Lipid oxidation was higher during the whole experimental period in the EX group (p = 0.004). Interestingly, fuel selection, assessed by the change in respiratory exchange ratio (RER), was increased in the EX session (p = 0.002). This was paralleled by a higher rate of SCAT lipolysis reflected by dialysate glycerol, plasma glycerol, and fatty acids (FA) levels (p < 0.001). Of note, we observed a significant relationship between whole-body fat oxidation and dialysate glycerol in both sessions (r (2) = 0.33, p = 0.02). In conclusion, this study highlights the limiting role of lipolysis and plasma FA availability to whole-body fat oxidation during exercise in endurance-trained subjects. This study shows that adipose tissue lipolysis is a determinant of fuel selection during exercise in healthy subjects.

[What is a vitamin?]. / Qu'est-ce qu'une vitamine?

In industrialized countries, the major vitamin deficiency syndromes have virtually disappeared. Today they are superseded by marginal deficits, characterized by insufficient vitamins reserves to maintain normal physiologic state. These states strike populations such as infants, pregnant women, alcoholics and the elderly, and may have long-term adverse effects on health. This assumption stems from the analysis of studies that show an increase in the incidence of various diseases such as cancers and cardiovascular, ocular and osteoarticular pathologies in subjects with low vitamin status. Although causal relationships are difficult to establish, a huge scope for public health appears to be open for vitamins, substituting the notion of minimal intake, indispensable to prevent signs of deficiency, to that ensuring optimal health in the medium and long-terms. However, the paradoxical character of the results obtained in several randomized trials should prompt caution in the use of vitamin supplements to prevent chronic diseases.

[Vitamin B1 (thiamine)]. / Vitamine B1 (thiamine).

Vitamin B1 (or thiamine) plays a key role in energy production from glucose. Since the main fuel of the nervous system is glucose, thiamine deficiency causes severe neurological symptoms. The biological exploration of vitamin B1 status is based on the measurement of thiamine pyrophosphate concentration or of the activity of a thiamine-dependent enzyme, transketolase, in erythrocytes. Severe deficiency states can be observed in chronic alcoholics, after protracted vomiting during pregnancy and after bariatric surgery. Mild deficiencies are common in the general population, but their clinical consequences are still unclear.

[Vitamin B9]. / Vitamine B9.

Vitamin B9 is represented by the group of folate, whose structure is derived from folic acid. The biologically active form is reduced tetrahydrofolates, serving as an essential cofactor in methylation reactions, including the vitamin B12-dependent formation of methionine from homocysteine, and as a carrier of one-carbon units involved in the synthesis of purines and pyrimidines. Folate deficiency is associated with hyperhomocysteinemia, megaloblastic anemia, leuco- and thrombocytopenia, cardiovascular disease, embryonic defects, in particular neural tube defects, and, possibly, malignancies, depression and cognitive impairment.

[Vitamin B12 (cobalamin)]. / Vitamine B12 (cobalamines).

The term "vitamin B12" refers to four cobalamins (Cbl), including methyl-Cbl and adenosyl-Cbl, the two enzyme co-factors of methionine synthase and methylmalonyl-CoA mutase, respectively. Vitamin B12 deficiency produces clinical disorders that include mainly megaloblastic anaemia, peripheral and central neurological manifestations. The clinical significance of low blood B12 concentrations in the absence of manifestations of deficiency is a matter of debate. The biochemical diagnosis of the subclinical and clinical deficiency of vitamin B12 has been enriched by several parameters, including serum methylmalonic acid, homocysteine, and holo-transcobalamine, which have been evaluated over the past two decades.

[Vitamin D]. / Vitamine D.

There is a recent renewed interest in vitamin D, due to its description as a hormone with a positive impact on global health. Even though many former epidemiological studies have suggested a possible link between a low vitamin D status and the risk of developing chronic diseases, recent data have proven to be more discordant or modest. Looking forward to clearly needed randomized intervention studies, optimal vitamin D status and intakes should be defined on the basis of the vitamin D indisputable effects on calcium homeostasis and skeletal mineralization.

Nitric oxide synthase inhibition and oxidative stress in cardiovascular diseases: possible therapeutic targets?

Nitric oxide (NO) is synthetized enzymatically from l-arginine (l-Arg) by three NO synthase isoforms, iNOS, eNOS and nNOS. The synthesis of NO is selectively inhibited by guanidino-substituted analogs of l-Arg or methylarginines such as asymmetric dimethylarginine (ADMA), which results from protein degradation in cells. Many disease states, including cardiovascular diseases and diabetes, are associated with increased plasma levels of ADMA. The N-terminal catalytic domain of these NOS isoforms binds the heme prosthetic group as well as the redox cofactor, tetrahydrobiopterin (BH(4)) associated with a regulatory protein, calmodulin (CaM). The enzymatic activity of NOS depends on substrate and cofactor availability. The importance of BH(4) as a critical regulator of eNOS function suggests that BH(4) may be a rational therapeutic target in vascular disease states. BH(4) oxidation appears to be a major contributor to vascular dysfunction associated with hypertension, ischemia/reperfusion injury, diabetes and other cardiovascular diseases as it leads to the increased formation of oxygen-derived radicals due to NOS uncoupling rather than NO. Accordingly, abnormalities in vascular NO production and transport result in endothelial dysfunction leading to various cardiovascular disorders. However, some disorders including a wide range of functions in the neuronal, immune and cardiovascular system were associated with the over-production of NO. Inhibition of the enzyme should be a useful approach to treat these pathologies. Therefore, it appears that both a lack and excess of NO production in diseases can have various important pathological implications. In this context, NOS modulators (exogenous and endogenous) and their therapeutic effects are discussed.

High levels of asymmetric dimethylarginine are strongly associated with low HDL in patients with acute myocardial infarction.

OBJECTIVES: Low levels of high-density lipoprotein (HDL) cholesterol are associated with an increased risk of acute myocardial infarction possibly through impaired endothelial atheroprotection and decreased nitric oxide (NO) bioavailability. Asymmetric dimethylarginine (ADMA) mediates endothelial function by inhibiting nitric oxide synthase activity. In patients with acute myocardial infarction, we investigated the relationship between serum levels of HDL and ADMA. APPROACH AND RESULTS: Blood samples from 612 consecutive patients hospitalized for acute MI <24 hours after symptom onset were taken on admission. Serum levels of ADMA, its stereoisomer, symmetric dimethylarginine (SDMA) and L-arginine were determined using high-performance liquid chromatography. Patients with low HDL (<40 mg/dL for men and <50 mg/dL for women) were compared with patients with higher HDL. Most patients (59%) had low HDL levels. Median ADMA levels were markedly higher in the low HDL group (0.69 vs. 0.50 µmole/L, p<0.001). In contrast, SDMA and L-arginine levels were similar for the two groups (p = 0.120 and p = 0.064). Notably, ADMA, but not SDMA or L-arginine, was inversely correlated with HDL (r = -0.311, p<0.001). In stratified analysis, this relationship was only found for low HDL levels (r = -0.265, p<0.001), but not when HDL levels were higher (r = -0.077, p = 0.225). By multivariate logistic regression analysis, ADMA level was strongly associated with low HDL levels (OR(95%CI):6.06(3.48-10.53), p<0.001), beyond traditional confounding factors. CONCLUSIONS: Our large population-based study showed for the first time a strong inverse relationship between HDL and ADMA in myocardial infarction patients, suggesting a functional interaction between HDL and endothelium, beyond metabolic conditions associated with low HDL levels.

Severe hypovitaminosis D correlates with increased inflammatory markers in HIV infected patients.

BACKGROUND: Even though it has been suggested that antiretroviral therapy has an impact on severe hypovitaminosis D (SHD) in HIV infected patients, it could be speculated that the different levels of residual inflammation on HAART (Highly Active Anti Retroviral Therapy) could contribute to SHD and aggravate bone catabolism in these patients. METHODS: A cross-sectional study was carried out in an unselected cohort of 263 HIV infected outpatients consulting during Spring 2010. Clinical examinations were performed and medical history, food habits, sun exposure and addictions were collected. Fasting blood samples were taken for immunological, virological, inflammation, endocrine and bone markers evaluations. RESULTS: Ninety-five (36%) patients had SHD. In univariate analysis, a significant and positive association was found between SHD and IL6 (p = 0.001), hsCRP (p = 0.04), increased serum C-Telopeptides X (CTX) (p = 0.005) and Parathyroid Hormon (PTH) (p < 0.0001) levels. In multivariate analysis, SHD deficiency correlated significantly with increased IL-6, high serum CTX levels, lower mean daily exposure to the sun, current or past smoking, hepatitis C, and functional status (falls), but not with the time spent on the current HAART (by specific drug or overall). CONCLUSIONS: SHD is frequent and correlates with inflammation in HIV infected patients. Since SHD is also associated with falls and increased bone catabolism, it may be of interest to take into account not only the type of antiretroviral therapy but also the residual inflammation on HAART in order to assess functional and bone risks. This finding also suggests that vitamin D supplementation may be beneficial in these HIV-infected patients.

Postnatal overfeeding in rats leads to moderate overweight and to cardiometabolic and oxidative alterations in adulthood.

In contrast to the masses of data on obesity, few data are available concerning the cardiometabolic and oxidative consequences of moderate overweight. The model of postnatal overfeeding (OF) induces an increase in body weight at weaning that remains during adult life. Litters of Wistar rats were either maintained at 12 pups (normal-fed group, NF), or reduced to 3 pups at birth in order to induce OF. At 6 months of age, metabolic parameters, circulating oxidative stress and aortic and coronary vasoreactivity were assessed. Cardiac susceptibility to ischemia-reperfusion injury was also evaluated ex vivo as were markers of cardiac remodeling. OF led to an increase in body weight at weaning (+50%); the increase in body weight persisted throughout adult life, but was less marked (+10%). Significant increases in plasma levels of fasting glucose, insulin and leptin were found in OF rats. An increase in both plasma hydroperoxides and cardiac superoxide dismutase activity and a decrease in plasma ascorbate were found in OF rats. Vasoreactivity was not modified, but ex vivo, after 30 min of ischemia, isolated hearts from OF rats showed lower recovery of coronary flow along with a greater release of LDH. Studies on heart tissues showed an increase in collagen content and increased expression and activity of MMP-2. Our findings show that moderate overweight in adult rats, induced by postnatal overfeeding, leads to both metabolic and oxidative disturbances as well as a higher susceptibility to cardiac injury after ischemia ex vivo, which may be explained, at least in part, by ventricular remodeling.

General oxidative stress during doxorubicin-induced cardiotoxicity in rats: absence of cardioprotection and low antioxidant efficiency of alpha-lipoic acid.

To evaluate the effects of alpha-lipoic acid (AL) in a model of doxorubicin (DOX)-induced cardiotoxicity, male Wistar rats were treated with DOX (1 mg/kg/d; 10 d) in combination or not with AL (50 mg/kg/d; 15 d). Plasma oxidative stress was determined by hydroperoxides (ROOH) and the ascorbyl radical/ascorbate ratio. One and two months later, the functional parameters of the hearts were determined in vivo by catheterization and cardiac oxidative stress was assessed by malonedialdehyde (MDA) and O2*⁻ (dihydroethidium fluorescence) content in tissue. After two months, body weight was higher in the DOX-AL group than in DOX (+16%), but this was due to ascites. Histological liver alterations were observed in both the DOX and DOX-AL groups. Plasma ROOH concentrations decreased after 10 days of AL treatment, but were greater in both the DOX and DOX-AL groups. After two months, a decrease in the cardiac contractility index (-27% and -29%, respectively) and cardiac hypertrophy were observed in DOX and DOX-AL. These dysfunctions were associated with 1) a reduction in plasma ascorbate levels and an increase in the ascorbyl/ascorbate ratio and 2) an increase MDA and O2*⁻ content in cardiac tissue. In conclusion, a cumulative dose of 10 mg/kg doxorubicin induced functional alterations in the heart associated with plasma and cardiac oxidative stress. The co-administration of the antioxidant compound AL had no beneficial effects in this situation.

Oxidative stress and myocardial gene alterations associated with Doxorubicin-induced cardiotoxicity in rats persist for 2 months after treatment cessation.

The molecular mechanisms underlying doxorubicin (DOX)-induced cardiomyopathy include alterations in cardiomyocytes' oxidative stress status and in gene expression. Although such alterations have been reported during in vivo DOX treatment of animals, it remains to be clarified whether they persist after treatment cessation. To address this question, rats were injected with either saline (1 ml/kg/day i.p; control) or DOX (1 mg/kg/day i.p.) for 10 days, and 70 days later cardiac functional parameters were evaluated in vivo by left ventricular catheterization. Hearts were also harvested for histological analyses as well as measurements of oxidative stress parameters by various techniques and gene expression by quantitative polymerase chain reaction of markers of cardiac pathological remodeling, namely atrial natriuretic factor, myosin heavy chain ß, vascular endothelial growth factor A (VEGF-A), and sarcoplasmic reticulum Ca(+2) ATPase. Compared with controls, DOX-treated rats displayed marked alterations in most parameters even 2 months after cessation of treatment. These included 1) lower left ventricular contractility (+dP/dt), 2) increased levels of plasma and myocardial oxidative stress markers, namely thiobarbituric acid reactive substances or dihydroethidium fluorescence, and 3) markedly altered transcript levels for all measured markers of cardiac remodeling, except VEGF-A. These changes correlated significantly with +dP/dt values assessed in the two groups of animals. In conclusion, this study demonstrated that as many as 2 months after cessation of DOX treatment cardiac alterations persisted, reflecting increased oxidative stress and pathological remodeling, the latter being linked to the development of contractile dysfunction.