Background-Meta-analyses predict that a 25% lowering of plasma homocysteine would reduce the risk of coronary heart disease by 11% to 16% and stroke by 19% to 24%. Individuals homozygous for the methylenetetrahydrofolate reductase (MTHFR) 677C3 T polymorphism have reduced MTHFR enzyme activity resulting from the inappropriate loss of the riboflavin cofactor, but it is unknown whether their typically high homocysteine levels are responsive to improved riboflavin status. Methods and Results-From a register of 680 healthy adults 18 to 65 years of age of known MTHFR 677C3 T genotype, we identified 35 with the homozygous (TT) genotype and age-matched individuals with heterozygous (CT, nϭ26) or wild-type (CC, nϭ28) genotypes to participate in an intervention in which participants were randomized by genotype group to receive 1.6 mg/d riboflavin or placebo for a 12-week period. Supplementation increased riboflavin status to the same extent in all genotype groups (8% to 12% response in erythrocyte glutathione reductase activation coefficient; PϽ0.01 in each case). However, homocysteine responded only in the TT group, with levels decreasing by as much as 22% overall (from 16.1Ϯ1.5 to 12.5Ϯ0.8 mol/L; Pϭ0.003; nϭ32) and markedly so (by 40%) in those with lower riboflavin status at baseline (from 22.0Ϯ2.9 and 13.2Ϯ1.0 mol/L; Pϭ0.010; nϭ16). No homocysteine response was observed in the CC or CT groups despite being preselected for suboptimal riboflavin status. Conclusions-Although previously overlooked, homocysteine is highly responsive to riboflavin, specifically in individuals with the MTHFR 677 TT genotype. Our findings might explain why this common polymorphism carries an increased risk of coronary heart disease in Europe but not in North America, where riboflavin fortification has existed for Ͼ50 years.

The present review focuses on the B-vitamins, i.e. folate, vitamin B 12 , vitamin B 6 and riboflavin, that are involved in homocysteine metabolism. Homocysteine is a S-containing amino acid and its plasma concentrations can be raised by various constitutive, genetic and lifestyle factors, by inadequate nutrient status and as a result of systemic disease and various drugs. Hyperhomocysteinaemia is a modest independent predictor of CVD and stroke, but causality and the precise pathophysiological mechanism(s) of homocysteine action remain unproven. The predominant nutritional cause of raised plasma homocysteine in most healthy populations is folate insufficiency. Vitamin B 12 and, to a lesser extent, vitamin B 6 are also effective at lowering plasma homocysteine, especially after homocysteine lowering by folic acid in those individuals presenting with raised plasma homocysteine. However, riboflavin supplementation appears to be effective at lowering plasma homocysteine only in those individuals homozygous for the T allele of the C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene. This gene codes for the MTHFR enzyme that produces methyltetrahydrofolate, which, in turn, is a substrate for the remethylation of homocysteine by the vitamin B 12 -dependent enzyme methionine synthase. Individuals with the MTHFR 677TT genotype are genetically predisposed to elevated plasma homocysteine, and in most populations have a markedly higher risk of CVD.Homocysteine: Folate: Vitamin B 12 : Vitamin B 6 : Riboflavin Epidemiological and experimental evidence is accumulating to indicate a probable role for certain B-vitamins in the prevention of CVD. Active forms of four B-vitamins, i.e. folate, vitamin B 12 , vitamin B 6 and riboflavin, are involved in the metabolism of a S-containing amino acid, homocysteine. Homocysteine metabolism links the methionine cycle with the folate cycle (Fig. 1). In most tissues and cells the major, or only, pathway for the conversion of homocysteine to methionine is the transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine, catalysed by the vitamin B 12 -dependent enzyme methionine synthase. One product of this reaction, methionine, can donate the methyl group via the activated form of methionine S-adenosylmethionine to a range of substrates, including proteins, phospholipids and DNA. The other product of the methionine synthase reaction, tetrahydrofolate, is reconverted to 5-methyltetrahydrofolate via the folate cycle. The reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate in the folate cycle is catalysed by the methylenetetrahydrofolate reductase (MTHFR) enzyme, which has a FAD (derived from riboflavin) prosthetic group. The metabolically-active form of vitamin B 6 , pyridoxal phosphate, is an enzyme cofactor for cystathionine b-synthase, which is involved in the catabolism of homocysteine to sulfate in the transsulfuration pathway (Fig.

We thank Powers et al for their positive comments on our article. 1 Their criticism is that our sample is not representative of the United Kingdom or European populations, and that our interpretation of the results in relation to food policy is therefore inappropriate.The statement that statistical inference is compromised is misleading because it is very clear in our article that the inference is not being made about the general population, but rather a subpopulation, ie, people homozygous for the MTHFR 677C3 T polymorphism (ie, TT genotype). To specifically investigate this subpopulation, we screened 680 healthy adults and identified just over 10% with the TT genotype; this is typical of populations worldwide. Powers et al have inappropriately compared homocysteine levels in our TT subpopulation with those found in the general UK population. The correct comparison is with other studies that report homocysteine levels in TT genotype subpopulations. Homocysteine values in one such meta-analysis 2 were comparable with our data and were 25% higher in people with TT compared with CC (wild-type) genotypes; however, the extent of elevation varied considerably between studies, 2 presumably because of differences in the prevailing status of folate and/or riboflavin. The elevated homocysteine in TT supopulations is generally far less marked within US compared with European populations where (unlike the United States) there is no exposure to mandatory fortification with folate or riboflavin. Correspondingly, this polymorphism carries an increased risk of cardiovascular disease in European populations but not in those in North America. 3 We feel that our findings can contribute to the debate regarding food fortification with folate and related B-vitamins currently being considered by many governments. In our study, 1 the marked homocysteine-lowering effect of riboflavin in people with the TT genotype was achieved with very low doses (1.6 mg/d, ie, recommended dietary level). If a sufficiently powered clinical trial proves that homocysteine is linked in a causative way to heart disease or stroke, then exposure of the general population to low-dose riboflavin through fortification (as in the United States) may offer a cheap, safe, and effective means of reducing disease risk among substantial subpopulations who carry the TT genotype and are unaware of it. DisclosuresNone. Helene

There is currently a lack of an efficient, objective and systemic approach towards the classification of Alzheimer’s disease (AD), due to its complex etiology and pathogenesis. As AD is inherently dynamic, it is also not clear how the relationships among AD indicators vary over time. To address these issues, we propose a hybrid computational approach for AD classification and evaluate it on the heterogeneous longitudinal AIBL dataset. Specifically, using clinical dementia rating as an index of AD severity, the most important indicators (mini-mental state examination, logical memory recall, grey matter and cerebrospinal volumes from MRI and active voxels from PiB-PET brain scans, ApoE, and age) can be automatically identified from parallel data mining algorithms. In this work, Bayesian network modelling across different time points is used to identify and visualize time-varying relationships among the significant features, and importantly, in an efficient way using only coarse-grained data. Crucially, our approach suggests key data features and their appropriate combinations that are relevant for AD severity classification with high accuracy. Overall, our study provides insights into AD developments and demonstrates the potential of our approach in supporting efficient AD diagnosis.

Background-Patients with cystic fibrosis experience chronic systemic oxidative stress. This is coupled with chronic inflammation of the lung involving bronchial polymorphonuclear neutrophil accumulation and activation. We hypothesised that, during periods of acute respiratory exacerbation, free radical activity and consequent damage would be most marked and that intensive treatment of the infection would result in improvement towards values found during stable periods. Methods-Plasma and red blood cells were collected from 12 healthy normal volunteers and from 12 patients with cystic fibrosis with an acute respiratory exacerbation (increased respiratory symptoms, reduction in forced expiratory volume in one second (FEV 1 ) of more than 10%, and a decision to treat with intravenous antibiotics). Further samples were collected from patients following two weeks of treatment. Samples were analysed for inflammatory markers, markers of free radical damage, and aqueous and lipid phase scavengers. Conclusions-Abnormalities of markers of inflammation, free radical activity, and radical scavengers were significantly more extreme during acute respiratory exacerbations and showed improvement with treatment. The need to provide protection from inflammation and free radical damage should therefore be dynamic and related to the inflammatory and oxidative processes. Results-During

Patients with cystic fibrosis (CF) experience a combination of chronic systemic oxidative stress, generation of free radicals in the lungs due to a hyperimmune response and a diminished ability to scavenge free radicals secondary to malabsorption and increased consumption. The authors asked the question, "Does breath isoprene content reflect systemic oxidative stress?"The study involved 12 CF patients and 12 matched healthy controls. The patients were sampled during acute respiratory exacerbation (increased respiratory symptoms, reduction in forced expiratory volume (FEV1) of >10%, and a decision to treat with intravenous antibiotics) and after two weeks of antibiotic treatment. Blood samples were examined for markers of oxidative stress. Breath samples were analysed for isoprene content.Malondialdehyde (MDA), erythrocyte membrane polyunsaturated fatty acids, protein sulphydryls and protein carbonyls all showed evidence of increased oxidative stress which was moderated by antibiotic treatment. Breath isoprene production rate was significantly lower in patients during exacerbation than in controls with a mean difference of -39 (95% confidence interval (CI) -11±57) pmol . min . kg -1 and increased to normal values following treatment (mean change 63 (95% CI 42±84) pmol . min . kg -1 ).In conclusion, breath isoprene cannot be considered a reliable marker of oxidative stress.

Although the use of low-calorie sweeteners (LCSs) is widespread, methods of assessing consumption within free-living populations have inherent limitations. Five commonly consumed LCSs, namely, acesulfame-K, saccharin, sucralose, cyclamate, and steviol glycosides, are excreted via the urine, and therefore a urinary biomarker approach may provide more objective LCS intake data. A LC-ESI-MS/MS method of simultaneously determining acesulfame-K, saccharin, sucralose, cyclamate, and the excretory metabolite of steviol glycosides, steviol glucuronide, in human urine was developed and validated. Linearity was observed over a concentration range of 10-1000 ng/mL with coefficients of determination ranging from 0.9969 to 0.9997. Accuracy ranged from 92 to 104%, and intrabatch and interday precisions were within acceptable limits with %CV below 8% for all compounds. A double-blind, randomized crossover dose-response study was conducted to assess the usefulness of urinary LCS excretions (from both fasting spot and a full 24-h urine collection) for investigating recent intakes. Both modes of sampling were useful for distinguishing between the three short-term intakes of acesulfame-K, saccharin, cyclamates, and steviol glycosides (p < 0.001), whereas for sucralose, urinary concentrations were useful for distinguishing between low (0.1% ADI) and high doses (10% ADI) only (p < 0.001). In summary, this biomarker approach may be useful for assessing intakes of five commonly consumed LCSs.

BackgroundAnxiety and depression are common, debilitating and costly. These disorders are influenced by multiple risk factors, from genes to psychological vulnerabilities and environmental stressors, but research is hampered by a lack of sufficiently large comprehensive studies. We are recruiting 40,000 individuals with lifetime depression or anxiety and broad assessment of risks to facilitate future research.MethodsThe Genetic Links to Anxiety and Depression (GLAD) Study (www.gladstudy.org.uk) recruits individuals with depression or anxiety into the NIHR Mental Health BioResource. Participants invited to join the study (via media campaigns) provide demographic, environmental and genetic data, and consent for medical record linkage and recontact.ResultsOnline recruitment was effective; 42,531 participants consented and 27,776 completed the questionnaire by end of July 2019. Participants’ questionnaire data identified very high rates of recurrent depression, severe anxiety, and comorbidity. Participants reported high rates of treatment receipt. The age profile of the sample is biased toward young adults, with higher recruitment of females and the more educated, especially at younger ages.DiscussionThis paper describes the study methodology and descriptive data for GLAD, which represents a large, recontactable resource that will enable future research into risks, outcomes, and treatment for anxiety and depression.