Homocysteine and cardiovascular disease

Fluorescence detection of glutathione and oxidized glutathione in blood with a NIR-excitable cyanine probe

Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids, and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase and the reducing agent nicotinamideadenine dinucleotide phosphate, without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems.

A novel fluorescent probe for imaging the process of HOCl oxidation and Cys/Hcy reduction in living cells

A new on-off-on fluorescent probe, CMOS, based on coumarin was developed to detect the process of hypochlorous acid (HOCl) oxidative stress and cysteine/homocysteine (Cys/Hcy) reduction. The probe exhibited a fast response, good sensitivity and selectivity. Moreover, it was applied for monitoring the redox process in living cells.

A new on–off–on fluorescent probe, CMOS, was designed and applied to detect the process of HOCl oxidation and Cys/Hcy reduction.

A fluorescence and UV/vis absorption dual-signaling probe with aggregation-induced emission characteristics for specific detection of cysteine

Biological thiols with similar structures, such as glutathione (GSH), N-acetyl-l-cysteine (NAC), homocysteine (Hcy) and cysteine (Cys), play important roles in human physiology and are associated with different diseases. Thus, the discrimination of these thiols is a great necessity for various biochemical investigations and the diagnosis of related diseases. Herein, we present a new dual-signaling probe consisting of a typical aggregation induced emission fluorogen of a tetraphenylethylene group and 2,4-dinitrobenzenesulfonyl moiety. The probe can be used to selectively and quantitatively detect Cys over a variety of bio-species, including GSH, NAC and Hcy, from both UV/vis absorption and fluorescence channels. The mechanism study showed that the fluorescence and UV/vis absorption were turned on as the probe undergoes displacement of the 2,4-dinitrobenzenesulfonyl group with Cys, where the UV/vis and fluorescence signals originate from the dinitrophenyl-containing compounds and aggregates of TPE-OH, respectively. In addition, the discrimination of Cys was achieved by more rapid intramolecular displacement of sulfur with the amino group of Cys than NAC, Hcy and GSH. Moreover, the probe shows ignorable cytotoxicity against HepG2 cells, which demonstrates the great potential of the probe in selectively detecting Cys in vivo.

A dual-signaling of fluorescence and UV/vis absorption modes for selective and quantitative detection of cysteine over homocysteine, N-acetyl-l-cysteine and glutathione is developed on the basis of aggregation-induced emission (AIE) effect.

Aldehyde-functionalized metal–organic frameworks for selective sensing of homocysteine over Cys, GSH and other natural amino acids

Aldehyde-functionalized luminescent MOFs represent the first example of MOF-implicated sensors for discriminating Hcy from Cys and GSH.

A Michael addition–cyclization-based switch-on fluorescent chemodosimeter for cysteine and its application in live cell imaging

We designed and synthesized a fast response fluorescent probe, BTAC (benzothiazol-azacoumarin), for detection of cysteine (Cys).

A multi-signal fluorescent probe for the discrimination of cysteine/homocysteine and glutathione and application in living cells and zebrafish

A multi-signal fluorescent probe for the discrimination of cysteine/homocysteine and glutathione was engineered in living cells by one-photon and two-photon modes and zebrafish by one-photon modes.

Influence of MTHFR gene variations on perceived stress modification: Preliminary results of NURSE study

Background: High level of perceived stress in nurses is due to a genetic predisposition and environmental stressors. The aim of NURSE (Nursing Unacquainted Related Stress Etiologies) study was to investigate the association of C677T MTHFR gene polymorphism and stress perception among nurses.

Methods: In this comprehensive study, 216 female nurses were recruited. Perceived stress was assessed using the Cohen Perceived Stress Scale (PSS). Genomic DNA was extracted from peripheral blood, and MTHFR genotype was detected by the polymerase chain reaction.

Results: MTHFR C677T genotype analysis revealed that half of the participants had normal C/C genotype, and the remaining half presented higher frequencies of C/T genotype (39.8%) compared to T/T genotype (10.2%). The mean±SD stress score in morning shift, night shift, and rotation was 15.39±4.75, 15.92±4.94, and 15.83±5.61, respectively (p= 0.7). Perceived stress score was more in highly educated group but it was not significant (p= 0.2). Distribution of different MTHFR genotypes in diverse groups revealed that in groups with more stress score, the frequency of heterozygote (C/T) and homozygote (T/T) genotypes increased. Data revealed that in low stress category, 87% of the participants had a normal genotype. However, in high stress category, 71.3% of the participants had a normal genotype.

Conclusion: MTHFR genotype, independent of folate availability and probable confounding parameters, might be a potential risk factor of perceived stress among nurses.

MTHFR A1298C and C677T Polymorphisms Are Associated with Increased Risk of Venous Thromboembolism: A Retrospective Chart Review Study

BACKGROUND

Methylene tetrahydrofolate reductase (MTHFR) is a key enzyme in homocysteine metabolism. This study aims to determine the impact of MTHFR polymorphisms on plasma homocysteine levels and risks of venous thromboembolism (VTE).

METHODS

This retrospective chart review study included a total of 188 subjects who were tested for MTHFR polymorphisms at Metrowest Coagulation Laboratory between April 2011 and April 2016. Two independent coders were trained to extract relevant clinical data for statistical analysis.

RESULTS

VTE occurred in 50% of patients with compound mutation, compared with only 28.6% of subjects from the wild-type group. Patients with heterozygous or homozygous A1298C or C677T variants had an intermediate risk of VTE. The median homocysteine level in the wild-type group was slightly lower than that of heterozygous or homozygous MTHFR variants. The difference, however, was not significant (p = 0.6193). Moreover, there was no difference in plasma homocysteine level between patients with VTE versus VTE-free (p = 0.4923).

CONCLUSIONS

Heterozygous or homozygous MTHFR variants, especially a compound mutation, are associated with increased risk of VTE. Hyperhomocysteinemia does not correlate with MTHFR polymorphisms or VTE risk. Hence, MTHFR genotyping provides more consistent assessment of VTE risk. This information can be incorporated into risk stratification for early intervention and prophylaxis of VTE.

Association between insulin resistance and total plasma homocysteine levels in type 2 diabetes mellitus patients in south west Nigeria

AIM

To determine the levels of serum homocysteine and its association with insulin resistance among T2DM patients at Obafemi Awolowo University Teaching Hospital, Ile Ife Nigeria.

METHODS

It was a cross sectional study. It involved consecutive recruitment of 100 T2DM subjects with 100 age and sex matched controls. The fasting plasma glucose, serum creatinine, fasting lipid profile, glycosylated haemoglobin levels, fasting serum insulin and plasma homocysteine concentration were done. Insulin resistance was also determined. SPSS version 17.0 was used for data analysis.

RESULTS

The mean age of subjects was not significantly different from controls. (58.9±8.3 vs. 59.0±8.3years, p=0.926 respectively). Mean Homocysteine level (tHcy) was significantly higher among T2DM subjects compared to controls (27.4±12.1 and 8.3±3.2μmol/L respectively, p=0.0001). Hyperhomocystinaemia was commoner among diabetic subjects compared with controls (81% vs. 5%, p<0.0001). T2DM with hyperhomocystinaemia were more likely to have poorer glucose control profile using glycated haemoglobin (7.4±1.9 vs 6.4±1.4%, p=0.04) and fasting blood glucose 8.6±2.2 vs 7.5±2.4mmol/L p=0.047 and insulin resistance (4.4±4.3 vs. 2.0±0.6, p=0.02) compared with T2DM with normohomocystenaemia. There were significant associations between hyperhomocystinaemic T2DM patients and IR, HbA1c, TC, TG and LDL cholesterol.

CONCLUSION

The study showed higher homocysteine levels in T2DM than controls. Homocysteine level is worsened by increasing insulin resistance, dyslipidaemia and poor glucose control. Homocysteine level is a potential cardiovascular risk marker in type 2 diabetic mellitus subjects.

The Effects of Methionine-Enriched and Vitamins (Folate, Pyridoxine and Cobalamine)-Deficient Diet on Exploratory Activity in Rats - A Brief Report

The aim of this study was to evaluate the impact of increased homocysteine levels induced by methionine nutritional overload (twice as standard) and deficiency of the vitamins folate, pyridoxine and cobalamine, which plays an important role in homocysteine metabolism in anxiety-related behaviour, expressed by means of exploratory activity in rats. Twenty-three male Wistar albino rats (4 weeks old, 100±15 g body weight) were divided into three groups: control (n=8), methionine-enriched (Meth+, 7.7 g of methionine/kg chow, n=7) and methionine-enriched vitamin-deficient (Meth+Vit-, 7.7 g of methionine/ kg chow, deficient in folate, pyridoxine and cobalamine - 0.08, 0.01 and 0.01 mg/kg, n=8). All animals had free access to food and water for 30 days. Behavioural testing was performed using the elevated plus maze (EPM) test. Standard parameters for vertical exploratory activity, the number of rearings and the number of head-dippings, as well as the total exploratory activity (summarizing overall exploratory activity in the EPM) were significantly reduced following 30 days of methionine nutritional overload (p<0.05, p<0.05 and p<0.01, respectively). A methionine-enriched diet coupled with a reduction in some B vitamins resulted in a more pronounced decline in exploratory drive observed in the EPM test compared to the control (p<0.01). The decline in total exploratory activity associated with vitamin deficiency was significant compared to the Meth+ group (p<0.05). The results of this study highlight the important role of homocysteine in the modulation of exploratory activity in rats. Decreased exploratory drive induced by both a methionine-enriched and vitamin-deficient diet could be attributed to an anxiogenic effect of hyperhomocysteinemia.

TOR-mediated regulation of metabolism in aging

Cellular metabolism is regulated by the mTOR kinase, a key component of the molecular nutrient sensor pathway that plays a central role in cellular survival and aging. The mTOR pathway promotes protein and lipid synthesis and inhibits autophagy, a process known for its contribution to longevity in several model organisms. The nutrient‐sensing pathway is regulated at the lysosomal membrane by a number of proteins for which deficiency triggers widespread aging phenotypes in tested animal models. In response to environmental cues, this recently discovered lysosomal nutrient‐sensing complex regulates autophagy transcriptionally through conserved factors, such as the transcription factors TFEB and FOXO, associated with lifespan extension. This key metabolic pathway strongly depends on nucleocytoplasmic compartmentalization, a cellular phenomenon gradually lost during aging. In this review, we discuss the current progress in understanding the contribution of mTOR‐regulating factors to autophagy and longevity. Furthermore, we review research on the regulation of metabolism conducted in multiple aging models, including Caenorhabditis elegans, Drosophila and mouse, and human iPSCs. We suggest that conserved molecular pathways have the strongest potential for the development of new avenues for treatment of age‐related diseases.

A plasma proteomics method reveals links between ischemic stroke and MTHFR C677T genotype

Methylene Tetrahydrofolate Reductase (MTHFR) catalyzes the conversion of methylene tetrahydrofolate to methylte trahydrofolate. The 677th nucleotide of the MTHFR gene is often regarded as a risk factor of cardiovascular disease. Previous studies demonstrated an elevated risk of ischemic stroke with the MTHFR677TT genotype. In this study, we employed a plasma proteomics method to investigate the connection between the polymorphism of the target nucleotide and stroke. In total, 28 protein spots were differentially expressed between the two groups, and of which, 25 protein spots were up-regulated and 3 were down-regulated. Five randomly selected spots were successfully identified as Haptoglobin (HPT) and Transferrin (TRFE). A functional analysis indicated that most of the differential expressed proteins (DEPs) were related to the inflammatory immune response. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these DEPs were involved in the complement cascade reaction. Meanwhile, protein-protein interactions (PPIs) analysis highlighted the novel association between the C677T MTHFR genotype and Vitamin D binding protein (DBP), which was confirmed by a molecular genetic analysis. The results suggested that the phenotype of the MTHFR might be associated with multiple proteins that have a synergistic effect, which might be related to the mechanism of ischemic stroke.

A near-infrared fluorescent probe based on BODIPY derivative with high quantum yield for selective detection of exogenous and endogenous cysteine in biological samples

Cysteine (Cys) is involved in cellular growth and Cys deficiency is related with many diseases. So far, a number of fluorescent probes have been constructed for the detection of Cys successfully. However, the probes are difficult to discriminate Cys from Hcy and the emission wavelength of the probes is in ultraviolet or visible range. Herein, a NIR fluorescent probe named NIR-BODIPY-Ac is synthesized and used to detect Cys. The emission wavelength of the probe is at 708 nm that belongs to near-infrared (NIR) region by attaching indolium to BODIPY core, which is suitable for bioimaging in vivo. Moreover, the probe exhibits high fluorescence quantum yield (Φ = 0.51) after the addition of Cys and high sensitivity toward Cys with 81-fold fluorescence enhancement. The linear range of the probe for Cys covers from 0.2 to 30 μM with a detection limit of 0.05 μM. Furthermore, the probe shows high selectivity towards Cys owing to the fact that there is more fast reaction rate between the probe and Cys than that of Hcy. In particular, the NIR fluorescent probe is applied for the detection of exogenous and endogenous Cys in biological samples such as cell, tissue and mouse with satisfactory results.

Homocysteine inhibits angiogenesis through cytoskeleton remodeling

Homocysteine (Hcy) is an intermediate non-diet amino acid connecting methionine and folate cycles. Elevated total Hcy level in blood, denoted as hyperhomocysteinemia, has emerged as a prevalent and strong risk factor for multiple diseases including atherosclerotic vascular disease in coronary, cerebral, and peripheral vessels. Its detrimental effect on vascular system implies the potential application as an inhibitor of angiogenesis. However, the detailed mechanism is unveiled. Inhibitory effect of Hcy was assessed on vascular endothelial growth factor (VEGF) induced cell proliferation and migration with endothelial cell (EC) culture system. Its effect on angiogenesis was further examined in vitro and in vivo After Hcy treatment, key angiogenic factors were measured by RT-qPCR. Cellular skeletal structure was also evaluated by actin stress fiber staining. VEGF-induced human umbilical vein EC (HUVEC) proliferation and migration were dramatically down-regulated by Hcy in a dose-responsive manner. Hcy treatment significantly inhibited the VEGF-induced angiogenesis in vitro by tube formation assay and chick chorioallantoic membrane (CAM) vessel formation in vivo Key angiogenic factors like VEGFR1/2 and angiopoietin (Ang)1/2 were substantially reduced by Hcy in HUVEC- and VEGF-induced actin stress fiber cytoskeletal structure was abolished. We demonstrated that Hcy could inhibit angiogenesis by targetting key angiogenic factor and disruption of actin cytoskeleton which is crucial for cell migration.

Muscular contraction frequency does not affect plasma homocysteine concentration in response to energy expenditure- and intensity-matched acute exercise in sedentary males

Acute exercise seems to increase total plasma homocysteine (tHcy); since this variable associated with cardiovascular risk, it is important to understand the determinants of its response to all types of exercise. The aim of this study was to examine the impact of cycling at 2 different rates of muscle contraction on the complete tHcy kinetics. Eight young sedentary males were required to complete 2 isocaloric (400 kcal) acute exercise trials at 50% peak oxygen uptake on separate occasions at 50 or 80 rpm. Blood samples were drawn at different points before (4 h before exercise and immediately before exercise), during (10, 20, 30, 45, and 60 min during exercise), and after exercise (immediately and 19 h after exercise). Dietary and lifestyle factors were controlled during the research. Maximum tHcy occurred during exercise for both conditions (50 rpm: 11.4 ± 2.7 μmol·L^-1; 80 rpm: 10.8 ± 3.2 μmol·L^-1). From this point onwards tHcy declined until the cessation of exercise and continued descending below pre-exercise values at 19 h postexercise (p < 0.05). No hyperhomocysteinemia were observed at any sampling point in both trials. In conclusion, the different muscular contraction frequency during exercise has no impact on tHcy during an acute bout of exercise in sedentary individuals, when at least 400 kcal are spent during exercise and the nutritional status for folate, B₁₂, and B₆ is adequate. This information is relevant to further inform healthy exercise prescription, not only in terms of duration and intensity of exercise, but also taking into account frequency of contraction.

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.

Blood lead, cadmium and mercury in relation to homocysteine and C-reactive protein in women of reproductive age: a panel study

BACKGROUND

To examine the relationship between cadmium, lead, and mercury concentrations with high-sensitivity C-reactive protein (hs-CRP) and homocysteine in women.

METHODS

Metals were measured at enrollment in whole blood. Homocysteine and hs-CRP were measured in one (N = 9) or two (N = 250) menstrual cycles up to 3 and 8 times per cycle, respectively. Linear mixed models with inverse probability of exposure weights to account for time varying confounding were used and models were stratified by dietary and serum vitamin status (dietary: vitamin B₆, B₁₂, folate; serum: folate).

RESULTS

Geometric mean (95% confidence interval (CI)) concentrations for cadmium, lead, and mercury were 0.29 (0.26-0.31) μg/L, 0.91 (0.86-0.96) μg/dL, and 1.05 (0.93-1.18) μg/L, respectively. Lead was associated with increased homocysteine (0.08; 95% CI: 0.01, 0.15) and this persisted among those in the lower three quartiles of consumption of vitamin B₆, B₁₂, folate, and serum folate but was not significant among those in the upper quartile. No associations were observed between metals and hs-CRP.

CONCLUSIONS

Blood lead was associated with increased homocysteine in a cohort of healthy, premenopausal women but these associations did not persist among those consuming ≥75th percentile of essential micronutrients. Cadmium, lead, and mercury were not associated with hs-CRP concentrations.

Cysteamine revisited: repair of arginine to cysteine mutations

Cysteamine is a small aminothiol endogenously derived from coenzyme A degradation. For some decades, synthetic cysteamine has been employed for the treatment of cystinosis, and new uses of the drug continue to emerge. In this review, we discuss the role of cysteamine in cellular and extracellular homeostasis and focus on the potential use of aminothiols to reconstitute the function of proteins harboring arginine (Arg) to cysteine (Cys) mutations, via repair of the Cys residue into a moiety that introduces an amino group, as seen in basic amino acid residues Lys and Arg. Cysteamine has been utilized in vitro and ex vivo in four different genetic disorders, and thus provides "proof of principle" that aminothiols can modify Cys residues. Other aminothiols such as mercaptoethylguanidine (MEG) with closer structural resemblance to the guanidinium moiety of Arg are under examination for their predicted enhanced capacity to reconstitute loss of function. Although the use of aminothiols holds clinical potential, more studies are required to refine specificity and treatment design. The efficacy of aminothiols to target proteins may vary substantially depending on their specific extracellular and intracellular locations. Redox potential, pH, and specific aminothiol abundance in each physiological compartment are expected to influence the reactivity and turnover of cysteamine and analogous drugs. Upcoming research will require the use of suitable cell and animal models featuring Arg to Cys mutations. Since, in general, Arg to Cys changes comprise about 8% of missense mutations, repair of this specific mutation may provide promising avenues for many genetic diseases.

Correlation between serum homocysteine concentration and severity of mitral valve disease in dogs

OBJECTIVE To measure serum homocysteine concentrations in dogs with myxomatous mitral valve disease (MMVD) and identify any association between this variable and stage of MMVD. ANIMALS 53 client-owned dogs with MMVD and 10 healthy control Beagles. PROCEDURES Dogs with MMVD were allocated to 3 groups in accordance with the staging system for chronic valvular heart disease in dogs and cats of the American College of Veterinary Internal Medicine. Blood samples were collected from all dogs, and serum homocysteine and cardiac troponin 1 concentrations were measured by enzyme immunoassay and chemiluminescence immunoassay, respectively. Analyte values were tested for associations with each other and with stage of MMVD. RESULTS A significant correlation was identified between serum homocysteine concentration and stage of MMVD. Mean ± SD concentrations were 6.72 ± 1.65 μmol/L for control dogs, 13.37 ± 4.16 μmol/L for dogs with stage B MMVD, 18.86 ± 6.73 μmol/L for dogs with stage C disease, and 28.26 ± 4.48 μmol/L for dogs with stage D disease. In addition, serum homocysteine concentration was correlated with serum cardiac troponin 1 (r = 0.34) and creatinine (r = 0.46) concentrations, systolic blood pressure (r = 0.57), and left atrium-to-aortic root ratio (r = 0.28), all of which were positively correlated with stage of MMVD. CONCLUSIONS AND CLINICAL RELEVANCE Serum homocysteine concentrations of dogs with MMVD were significantly higher than those of control dogs, and significant correlations were identified between these values and several risk factors for heart failure. Measurement of serum homocysteine concentration may be useful in the prediction of severity of disease in dogs with MMVD.

Chronic transgenerational vitamin B12 deficiency of severe and moderate magnitudes modulates adiposity-probable underlying mechanisms

We have demonstrated previously that severe but not moderate vitamin B12 deficiency altered body composition and induced adiposity in female C57BL/6 mice. This study aims to elucidate the effects of chronic transgenerational dietary vitamin B12 restriction on body composition and various biochemical parameters in the F1 generation offspring of our mouse models of severe and moderate vitamin B12 deficiency established earlier. Female weanling C57BL/6 mice received, ad libitum, for 4 weeks a (i) control diet, (ii) vitamin B12-restricted diet with pectin as dietary fiber (severely deficient diet), or (iii) vitamin B12-restricted diet with cellulose as dietary fiber (moderately deficient diet) and then mated with control males. The offspring of control and severely deficient dams continued on the respective diets of their mothers. Few moderately deficient dams were rehabilitated to control diet from parturition and their pups were weaned to control diet. Also, some offspring born to moderately B12 deficient dams were weaned to control diet, while others continued on the same diet as their mothers. Various parameters were determined in the F1 offspring after 12 and 36 weeks of feeding. The results indicate that both severe and moderate maternal vitamin B12 restrictions were associated with accelerated catch-up growth, increased body fat percentage, visceral adiposity, dyslipidemia, fasting hyperglycemia and insulin resistance in the F1 offspring. Inflammation, increased glucocorticoid and oxidative stress and poor antioxidant defence probably underlie these adverse effects. Rehabilitation from parturition but not weaning was beneficial in delaying the onset of the adverse outcomes in the offspring. © 2016 BioFactors, 43(3):400-414, 2017.

Characterization and Interrelations of One-Carbon Metabolites in Tissues, Erythrocytes, and Plasma in Mice with Dietary Induced Folate Deficiency

Studies on one-carbon metabolism for the assessment of folate deficiency have focused on either metabolites of folate metabolism or methionine cycle. To bridge the gap between deficiency markers in these pathways we designed a dietary induced folate deficiency study using male C57BL/6N mice. After weaning (3 weeks) mice were fed a defined control diet (1 week) before being fed a folate deficient diet (n = 6 mice) and the control diet (n = 6 mice) for 12 additional weeks. Thereafter, we determined total homocysteine in plasma and folate in erythrocytes as well as S-adenosylmethionine, S-adenosylhomocysteine, and six folate vitamers in tissues including 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, 5,10-methenyltetrahydrofolate, tetrahydrofolate, 10-formylfolic acid, and folic acid by means of stable isotope dilution assays coupled with liquid chromatography tandem mass spectrometry. In all organs, except heart (mainly 5-mehtyltetrahydrofolate), tetrahydrofolate constitutes the main vitamer. Moreover, in liver tetrahydrofolate was most abundant followed by 5-methyltetrahydrofolate (heart: tetrahydrofolate), 5-formyltetrahydrofolate, and 5,10-methenyltetrahydrofolate. Because of the significant decrease (p < 0.05) of folate status and S-adenosylmethionine/S-adenosylhomocysteine ratio accompanied with increasing S-adenosylhomocysteine (p < 0.05), hepatocytes are most susceptible to folate deficiency. To the best of our knowledge, we herein present the first method for simultaneous quantitation of eight metabolites for both folate and methionine cycle in one tissue sample, tHcy in plasma, and erythrocyte folate to shed light on physiological interrelations of one-carbon metabolism.

A Ratiometric Near-Infrared Fluorogen for the Real Time Visualization of Intracellular Redox Status during Apoptosis

Direct monitoring of apoptotic progression is a major step forward for the early assessment of therapeutic efficacy of certain treatments and the accurate evaluation of the spread of a disease. Here, the regulatory role of glutathione (GSH) is explored as a potential biomarker for tracking apoptosis. For this purpose, a near- infrared (NIR) squaraine dye is introduced that is capable of sensing GSH in a ratiometric manner by switching its emission from NIR (690 nm) to visible region (560 nm). The favorable biocompatible attributes of the probe facilitated the real-time monitoring of apoptotic process in line with the conventional apoptotic assay. Furthermore, the robust nature of the probe was utilized for the quantitative estimation of GSH during different stages of apoptosis. Through this study, an easy and reliable method of assaying apoptosis is demonstrated, which can provide valuable insights in translational clinical research.

Associations between homocysteine metabolism related SNPs and carotid intima-media thickness: a Chinese sib pair study

Carotid intima-media thickness (CIMT) is a good surrogate for atherosclerosis. Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. We aim to investigate the relationships between homocysteine (Hcy) related biochemical indexes and CIMT, the associations between Hcy related SNPs and CIMT, as well as the potential gene–gene interactions. The present study recruited full siblings (186 eligible families with 424 individuals) with no history of cardiovascular events from a rural area of Beijing. We examined CIMT, intima-media thickness for common carotid artery (CCA-IMT) and carotid bifurcation, tested plasma levels for Hcy, vitamin B6 (VB6), vitamin B12 (VB12) and folic acid (FA), and genotyped 9 SNPs on MTHFR, MTR, MTRR, BHMT, SHMT1, CBS genes. Associations between SNPs and biochemical indexes and CIMT indexes were analyzed using family-based association test analysis. We used multi-level mixed-effects regression model to verify SNP-CIMT associations and to explore the potential gene–gene interactions. VB6, VB12 and FA were negatively correlated with CIMT indexes (p < 0.05). rs2851391 T allele was associated with decreased plasma VB12 levels (p = 0.036). In FABT, CBS rs2851391 was significantly associated with CCA-IMT (p = 0.021) and CIMT (p = 0.019). In multi-level mixed-effects regression model, CBS rs2851391 was positively significantly associated with CCA-IMT (Coef = 0.032, se = 0.009, raw p < 0.001) after Bonferoni correction (corrected α = 0.0056). Gene–gene interactions were found between CBS rs2851391 and BHMT rs10037045 for CCA-IMT (p = 0.011), as well as between CBS rs2851391 and MTR rs1805087 for CCA-IMT (p = 0.007) and CIMT (p = 0.022). Significant associations are found between Hcy metabolism related genetic polymorphisms, biochemical indexes and CIMT indexes. There are complex interactions between genetic polymorphisms for CCA-IMT and CIMT.

Association of C677T transition of the human methylenetetrahydrofolate reductase (MTHFR) gene with male infertility

The human methylenetetrahydrofolate reductase (MTHFR) gene encodes one of the key enzymes in folate metabolism. This gene is located on chromosome 1 (1p36.3), which has 12 exons. The aim of the present study was to investigate the possible association of the two (C677T and A1298C) polymorphisms of this gene with male infertility. In a case-control study, 250 blood samples were collected from IVF centres in Sari and Babol (Iran): 118 samples were from oligospermic men and 132 were from controls. Two single nucleotide polymorphisms of the MTHFR genotype were detected using polymerase chain reaction-restriction fragment length polymorphism. There was no association found between the A1298C variant and male infertility. However, carriers of the 677T allele (CT and TT genotypes) were at a higher risk of infertility than individuals with other genotypes (odds ratio 1.84; 95% confidence interval 1.11-3.04; P=0.0174). Structural analysis of human MTHFR flavoprotein showed that C677T transition played an important role in the change in affinity of the MTHFR-Flavin adenine dinucleotide binding site. Based on our results, we suggest that C677T transition in MTHFR may increase the risk of male infertility, and detection of the C677T polymorphism biomarker may be helpful in the screening of idiopathic male infertility.

Combinatorial Strategy to Identify Fluorescent Probes for Biothiol and Thiophenol Based on Diversified Pyrimidine Moieties and Their Biological Applications

We present a feasible paradigm of developing original fluorescent probes for target biomolecules via combinatorial chemistry. In this developmental program, pyrimidine moieties were investigated and optimized as unique recognition units for thiols for the first time through a parallel synthesis in combination with a rapid screening process. This time-efficient and cost-saving process effectively facilitated the developmental progress and provided detailed structure-reactivity relationships. As a result, Res-Biot and Flu-Pht were identified as optimal fluorescent probes for biothiol and thiophenol, respectively. Their favorable characteristics and superior applicability have been well demonstrated in both chemical and biological contexts. In particular, Res-Biot enables the direct visualization of biothiol fluctuations during oxidative stress and cell apoptosis, indicating its suitability in elucidation of a specific pathophysiological process in both living cells and living animals. Meanwhile, Flu-Pht is competent to visualize thiophenols without the interference from endogenous biothiols in living cells.

Maternal lipid profile and the relation with spontaneous preterm delivery: a systematic review

BACKGROUND

It is unknown whether an unfavorable (atherogenic) lipid profile and homocysteine level, which could supersede clinical cardiovascular disease, is also associated with an increased risk of spontaneous preterm delivery (sPTD). A systematic review of studies assessing the lipid profile and homocysteine value of women with sPTD compared to women with term delivery in pre-pregnancy and during pregnancy.

METHODS

A systematic search of peer-reviewed articles published between January 1980 and May 2014 was performed using MEDLINE, EMBASE and the Cochrane database. We included case-control and cohort studies that examined triglycerides, high/low density lipoprotein cholesterol, total cholesterol and homocysteine in women with sPTD. Articles were subdivided in pre-pregnancy, first, second and third trimester. Of 708 articles reviewed for eligibility, 14 met our inclusion criteria.

RESULTS AND CONCLUSION

Nine cohort studies and five case-control studies were analyzed, reporting on 1466 cases with sPTD and 11296 controls with term delivery. The studies suggest a possible elevated risk of sPTD in woman with high TG levels, no association of high and low density lipoprotein cholesterol with the risk of sPTD was found. High homocysteine levels are associated with sPTD in the second trimester. The role of triglycerides and homocysteine in sPTD should be explored further.

Associations of Maternal Vitamin B12 Concentration in Pregnancy With the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data

Vitamin B12 (hereafter referred to as B12) deficiency in pregnancy is prevalent and has been associated with both lower birth weight (birth weight <2,500 g) and preterm birth (length of gestation <37 weeks). Nevertheless, current evidence is contradictory. We performed a systematic review and a meta-analysis of individual participant data to evaluate the associations of maternal serum or plasma B12 concentrations in pregnancy with offspring birth weight and length of gestation. Twenty-two eligible studies were identified (11,993 observations). Eighteen studies were included in the meta-analysis (11,216 observations). No linear association was observed between maternal B12 levels in pregnancy and birth weight, but B12 deficiency (<148 pmol/L) was associated with a higher risk of low birth weight in newborns (adjusted risk ratio = 1.15, 95% confidence interval (CI): 1.01, 1.31). There was a linear association between maternal levels of B12 and preterm birth (per each 1-standard-deviation increase in B12, adjusted risk ratio = 0.89, 95% CI: 0.82, 0.97). Accordingly, B12 deficiency was associated with a higher risk of preterm birth (adjusted risk ratio = 1.21, 95% CI: 0.99, 1.49). This finding supports the need for randomized controlled trials of vitamin B12 supplementation in pregnancy.

Specific pH effect for selective colorimetric assay of glutathione using anti-aggregation of label-free gold nanoparticles

An operationally simple colorimetric method for measuring glutathione (GSH) concentration was developed using anti-aggregation of gold nanoparticles (AuNPs) in this work.

A polymer-based probe for specific discrimination of cysteine

A kind of polymer-based turn-on fluorescent probe for specific detection of cysteine with high sensitivity has been developed.

A highly water-soluble, sensitive, coumarin-based fluorescent probe for detecting thiols, and its application in bioimaging

In this study, a coumarin-based probe (probe 1) bearing a maleimide group was used to rapidly and selectively detect thiols.

A fluorescein-based chemosensor for relay fluorescence recognition of Cu(ii) ions and biothiols in water and its applications to a molecular logic gate and living cell imaging

Relay recognition of copper(ii) ions and biothiolsviaa fluorescence “on–off–on” cascade has been realized in 100% aqueous solution when excited by the visible light.

Selective Fluorescent Detection of Cysteine over Homocysteine and Glutathione by a Simple and Sensitive Probe

A simple fluorescent probe able to selectively and sensitively detect cysteine (Cys) with an excellent dose-dependent relationship between fluorescence intensity and concentration of Cys from 0 to 100 μM has been designed and synthesised.

A gold nanocluster-based ratiometric fluorescent probe for cysteine and homocysteine detection in living cells

A novel organic–inorganic ratiometric fluorescent probe AuNCs–NBD was developed for the detection of cysteine (Cys) and homocysteine (Hcy).

A near-infrared phosphorescent iridium(iii) complex for imaging of cysteine and homocysteine in living cells and in vivo

A novel NIR-emitting iridium(iii) complex was developed to detect Cys/Hcy levels in vitro and in vivo.

Conformational status of cytochrome c upon N-homocysteinylation: Implications to cytochrome c release

One of the proposed mechanisms of homocysteine (Hcy) toxicity is the post-translational modification of proteins by its metabolite, homocysteine thiolactone (HTL). Incubation of proteins with HTL has been shown to form covalent adducts with ε-amino group of lysine residues of protein (called N-homocysteinylation) which ultimately results in structural and functional alterations of the modified proteins. In the present study, the effects of HTL on the conformational and heme status of cytochrome c (cyt c) were investigated. Spectroscopic analyses revealed that HTL-modified cyt c undergoes certain conformational alterations leading to disturbed heme-Trp distance and packing of the apolar groups. These alterations were accompanied with the reduction of the heme moiety and activation of peroxidase-like function of cyt c, which is known to be a crucial event for initiation of the intrinsic apoptotic pathway. Further structural characterization revealed that disruption of the heme-Met80 interaction, thereby converting the hexa-coordinate cyt c to a penta-coordinate species (with a free heme ligand), was responsible for the activation of the peroxidase activity. The study provides insights for the possible role of cyt c N-homocysteinylation in eliciting its toxicity and cell death.

In Vitro Interaction Between Homocysteine and Copper Ions: Potential Redox Implications

Homocysteine (Hcys) has been implicated in various oxidative stress-related disorders. The presence of a thiol on its structure allows Hcys to exert a double-edge redox action. Depending on whether Cu2+ ions occur concomitantly, Hcys can either promote or prevent free radical generation and its consequences. We have addressed In vitro the interaction between Hcys and Cu2+ Ions, in terms of the consequences that such interaction may have on the free radical scavenging properties of Hcys and on the redox state and redox activity of the metal. To this end, we investigated the free radical-scavenging, O2--generating, and ascorbate-oxidizing properties of the interacting species by assessing the bleaching of ABTS'+ radicals, the reduction of O2--dependent cytochrome c, and the copper-dependent oxidation of ascorbate, respectively. In addition, electron paramagnetic resonance and Cu(I)-bathocuproine formation were applied to assess the formation of paramagnetic complexes and the metal redox state. Upon a brief incubation, the Hcys/Cu2+ Interaction led to a decrease in the free radical-scavenging properties of Hcys, and to a comparable loss of the thiol density. Both effects were partial and were not modified by increasing the Incubation time, despite the presence of Cu2+ excess. Depending on the molar Hcys : Cu2+ ratio, the interaction resulted in the formation of mixtures that appear to contain time-stable and ascorbate-reducible Cu(II) complexes (for ratios up to 2:1), and ascorbate- and oxygen-redox-inactive Cu(l) complexes (for ratios up to 4:1). Increasing the interaction ratio beyond 4:1 was associated with the sudden appearance of an O2--generating activity. The data indicate that depending on the molar ratio of interaction, Hcys and Cu2+ react to form copper complexes that can promote either antioxidant or pro-oxidant actions. We speculate that the redox activity arising from a large molar Hcys excess may partially underlie the association between hyper-homocysteinemia and a greater risk of developing oxidative-related cardiovascular diseases.