Oxidation Of Choline Research Articles

Molecular genetic analysis of candidate genes for glutaric aciduria type II in a cohort of patients from Queensland, Australia

Glutaric aciduria type II (GAII) is a heterogeneous genetic disorder affecting mitochondrial fatty acid, amino acid and choline oxidation. Clinical manifestations vary across the lifespan and onset may occur at any time from the early neonatal period to advanced adulthood. Historically, some patients, in particular those with late onset disease, have experienced significant benefit from riboflavin supplementation. GAII has been considered an autosomal recessive condition caused by pathogenic variants in the gene encoding electron-transfer flavoprotein ubiquinone-oxidoreductase (ETFDH) or in the genes encoding electron-transfer flavoprotein subunits A and B (ETFA and ETFB respectively). Variants in genes involved in riboflavin metabolism have also been reported. However, in some patients, molecular analysis has failed to reveal diagnostic molecular results. In this study, we report the outcome of molecular analysis in 28 Australian patients across the lifespan, 10 paediatric and 18 adult, who had a diagnosis of glutaric aciduria type II based on both clinical and biochemical parameters. Whole genome sequencing was performed on 26 of the patients and two neonatal onset patients had targeted sequencing of candidate genes. The two patients who had targeted sequencing had biallelic pathogenic variants (in ETFA and ETFDH). None of the 26 patients whose whole genome was sequenced had biallelic variants in any of the primary candidate genes. Interestingly, nine of these patients (34.6%) had a monoallelic pathogenic or likely pathogenic variant in a single primary candidate gene and one patient (3.9%) had a monoallelic pathogenic or likely pathogenic variant in two separate genes within the same pathway. The frequencies of the damaging variants within ETFDH and FAD transporter gene SLC25A32 were significantly higher than expected when compared to the corresponding allele frequencies in the general population. The remaining 16 patients (61.5%) had no pathogenic or likely pathogenic variants in the candidate genes. Ten (56%) of the 18 adult patients were taking the selective serotonin reuptake inhibitor antidepressant sertraline, which has been shown to produce a GAII phenotype, and another two adults (11%) were taking a serotonin-norepinephrine reuptake inhibitor antidepressant, venlafaxine or duloxetine, which have a mechanism of action overlapping that of sertraline. Riboflavin deficiency can also mimic both the clinical and biochemical phenotype of GAII. Several patients on these antidepressants showed an initial response to riboflavin but then that response waned. These results suggest that the GAII phenotype can result from a complex interaction between monoallelic variants and the cellular environment. Whole genome or targeted gene panel analysis may not provide a clear molecular diagnosis.

RNAi screens identify HES4 as a regulator of redox balance supporting pyrimidine synthesis and tumor growth.

NADH/NAD+ redox balance is pivotal for cellular metabolism. Systematic identification of NAD(H) redox regulators, although currently lacking, would help uncover unknown effectors critically implicated in the coordination of growth metabolism. In this study, we performed a genome-scale RNA interference (RNAi) screen to globally survey the genes involved in redox modulation and identified the HES family bHLH transcription factor HES4 as a negative regulator of NADH/NAD+ ratio. Functionally, HES4 is shown to be crucial for maintaining mitochondrial electron transport chain (ETC) activity and pyrimidine synthesis. More specifically, HES4 directly represses transcription of SLC44A2 and SDS, thereby inhibiting mitochondrial choline oxidation and cytosolic serine deamination, respectively, which, in turn, ensures coenzyme Q reduction capacity for DHODH-mediated UMP synthesis and serine-derived dTMP production. Accordingly, inhibition of choline oxidation preserves mitochondrial serine catabolism and ETC-coupled redox balance. Furthermore, HES4 protein stability is enhanced under EGFR activation, and increased HES4 levels facilitate EGFR-driven tumor growth and predict poor prognosis of lung adenocarcinoma. These findings illustrate an unidentified mechanism, underlying pyrimidine biosynthesis in the intersection between serine and choline catabolism, and underscore the physiological importance of HES4 in tumor metabolism.

Choline degradation in Paracoccus denitrificans: identification of sources of formaldehyde.

Paracoccus denitrificans is a facultative methylotroph that can grow on methanol and methylamine as sole sources of carbon and energy. Both are oxidized to formaldehyde and then to formate, so growth on C1 substrates induces the expression of genes encoding enzymes required for the oxidation of formaldehyde and formate. This induction involves a histidine kinase response regulator pair (FlhSR) that is likely triggered by formaldehyde. Catabolism of some complex organic substrates (e.g., choline and L-proline betaine) also generates formaldehyde. Thus, flhS and flhR mutants that fail to induce expression of the formaldehyde catabolic enzymes cannot grow on methanol, methylamine, and choline. Choline is oxidized to glycine via glycine betaine, dimethylglycine, and sarcosine. By exploring flhSR growth phenotypes and the activities of a promoter and enzyme known to be upregulated by formaldehyde, we identify the oxidative demethylations of glycine betaine, dimethylglycine, and sarcosine as sources of formaldehyde. Growth on glycine betaine, dimethylglycine, and sarcosine is accompanied by the production of up to three, two, and one equivalents of formaldehyde, respectively. Genetic evidence implicates two orthologous monooxygenases in the oxidation of glycine betaine. Interestingly, one of these appears to be a bifunctional enzyme that also oxidizes L-proline betaine (stachydrine). We present preliminary evidence to suggest that growth on L-proline betaine induces expression of a formaldehyde dehydrogenase distinct from the enzyme induced during growth on other formaldehyde-generating substrates.IMPORTANCEThe bacterial degradation of one-carbon compounds (methanol and methylamine) and some complex multi-carbon compounds (e.g., choline) generates formaldehyde. Formaldehyde is toxic and must be removed, which can be done by oxidation to formate and then to carbon dioxide. These oxidations provide a source of energy; in some species, the CO2 thus generated can be assimilated into biomass. Using the Gram-negative bacterium Paracoccus denitrificans as the experimental model, we infer that oxidation of choline to glycine generates up to three equivalents of formaldehyde, and we identify the three steps in the catabolic pathway that are responsible. Our work sheds further light on metabolic pathways that are likely important in a variety of environmental contexts.

Bi-enzyme assay coupled with silver nanoplate transformation for insecticide detection.

A novel colorimetric method utilizing a bi-enzyme assay using silver nanoplates (AgNPls) as a direct signal source was developed to enable rapid insecticide detection. This innovative system leverages the in situ generated H2O2 from the consecutive enzyme-catalyzed reactions of acetylcholine hydrolysis and choline oxidation to introduce oxidative etching of AgNPls, transforming them into aggregated silver nanospheres (AgNSs). The morphological transformation of silver nanoparticles could be observed with the naked eye due to the solution's color shifts from pink-violet to blue-violet. The presence of insecticide, i.e., dichlorvos (DDVP), could inhibit acetylcholinesterase activity, thereby limiting H2O2 production and affecting the transformation of AgNPls into aggregated AgNSs. Furthermore, the extent of AgNPl-to-aggregated AgNS transformation and the subsequent solution's color change was inversely proportional to the amount of DDVP. Under optimal conditions, the developed bi-enzyme assay enables the quantification of DDVP within 5 minutes, achieving detection limits of 0.5 ppm and 0.1 ppm by naked-eye detection and UV-visible spectrophotometry, respectively. Furthermore, the practical application of this assay was validated for detecting insecticides in real vegetable samples, demonstrating both accuracy and reliability.

Vitamin B and One-Carbon Metabolite Profiles Show Divergent Associations with Cardiometabolic Risk Markers but not Cognitive Function in Older New Zealand Adults: A Secondary Analysis of the REACH Study

BackgroundVitamin B inadequacies and elevated homocysteine status have been associated with impaired cognitive and cardiometabolic health with aging. There is, however, a scarcity of research investigating integrated profiles of one-carbon (1C) metabolites in this context, including metabolites of interconnected folate, methionine, choline oxidation, and transsulfuration pathways. ObjectivesThe study aimed to examine associations between vitamins B and 1C metabolites with cardiometabolic health and cognitive function in healthy older adults, including the interactive effects of Apolipoprotein E-ε4 status. MethodsThree hundred and thirteen healthy participants (65-74 y, 65% female) were analyzed. Vitamins B were estimated according to dietary intake (4-d food records) and biochemical status (serum folate and vitamin B12). Fasting plasma 1C metabolites were quantified by liquid chromatography with tandem mass spectrometry. Measures of cardiometabolic health included biochemical (lipid panel, blood glucose) and anthropometric markers. Cognitive function was assessed by the Computerized Mental Performance Assessment System (COMPASS) and Montreal Cognitive Assessment (MoCA). Associations were analyzed using multivariate linear (COMPASS, cardiometabolic health) and Poisson (MoCA) regression modeling. ResultsOver 90% of participants met dietary recommendations for riboflavin and vitamins B6 and B12, but only 78% of males and 67% of females achieved adequate folate intakes. Higher serum folate and plasma betaine and glycine concentrations were associated with favorable cardiometabolic markers, whereas higher plasma choline and homocysteine concentrations were associated with greater cardiometabolic risk based on body mass index and serum lipids concentration values (P< 0.05). Vitamins B and homocysteine were not associated with cognitive performance in this cohort, though higher glycine concentrations were associated with better global cognitive performance (P = 0.017), episodic memory (P = 0.016), and spatial memory (P = 0.027) scores. Apolipoprotein E-ε4 status did not modify the relationship between vitamins B or 1C metabolites with cognitive function in linear regression analyses. ConclusionsVitamin B and 1C metabolite profiles showed divergent associations with cardiometabolic risk markers and limited associations with cognitive performance in this cohort of healthy older adults.

CHDH, a key mitochondrial enzyme, plays a diagnostic role in metabolic disorders diseases and tumor progression.

Human choline dehydrogenase (CHDH) is a transmembrane protein located in mitochondria. CHDH has been shown to be one of the important catalytic enzymes that catalyze the oxidation of choline to betaine and is involved in mitochondrial autophagy after mitochondrial damage. In recent years, an increasing number of studies have focused on CHDH and found a close association with the pathogenesis of various diseases, including tumor prognosis. Here we summarized the genomic localization, protein structure and basic functions of CHDH and discuss the progress of CHDH research in metabolic disorders and other diseases. Moreover, we described the regulatory role of CHDH on the progression of different types of malignant tumors. In addition, major pathogenic mechanisms of CHDH in multiple diseases may be associated with single nucleotide polymorphism (SNP). We look forward to providing new strategies and basis for clinical diagnosis and prognosis prediction of diseases by diagnosing SNP loci of CHDH genes. Our work evaluates the feasibility of CHDH as a molecular marker relevant to the diagnosis of some metabolic disorders diseases and tumors, which may provide new targets for the treatment of related diseases and tumors.

Healthy Nordic diet and associations with plasma concentrations of metabolites in the choline oxidation pathway: a cross-sectional study from Northern Sweden

BackgroundThe choline oxidation pathway and metabolites involved have been linked to diseases including cardiovascular disease, type 2 diabetes and cancer. A healthy Nordic diet is a recently defined dietary pattern associated with decreased risk for these diseases. Our aim was to explore associations between adherence to a healthy Nordic diet and plasma concentrations of metabolites of the choline oxidation pathway.MethodsThe Healthy Nordic Food Index (HNFI) and Baltic Sea Diet Score (BSDS) were applied to cross-sectional data (n = 969) from the Västerbotten Intervention Programme in Northern Sweden to score adherence to a healthy Nordic diet. Data included responses to a dietary questionnaire and blood sample analyses (1991–2008). Associations of diet scores with plasma concentrations of metabolites of the choline oxidation pathway and total homocysteine (tHcy), seven metabolites in total, were evaluated with linear regression, adjusting for age, BMI, education and physical activity.ResultsHNFI scores showed linear relationships with plasma choline (β = 0.11), betaine (β = 0.46), serine (β = 0.98) and tHcy (β = − 0.38), and BSDS scores with betaine (β = 0.13) and tHcy (β = − 0.13); unstandardized beta coefficients, all significant at P < 0.05. The regression models predicted changes in plasma metabolite concentrations (± 1 SD changes in diet score) in the range of 1–5% for choline, betaine, serine and tHcy. No other statistically significant associations were observed.ConclusionsA healthy Nordic diet was associated with plasma concentrations of several metabolites of the choline oxidation pathway. Although relationships were statistically significant, effect sizes were moderate. Further research is warranted to explore the underlying mechanisms and associations with health outcomes.

Integrated enzyme-linked immunosensor with biofunctionalized ion-selective membranes by pulstrode delivery of substrate

A new principle for electrochemical enzyme immunoassays is proposed where the enzyme substrate is selectively delivered by an electrochemical excitation pulse to the location where the biomolecular interaction takes place. This is achieved by covalent attachment of the capture antibody on the surface of a polymeric ion-selective membrane, which also serves to monitor the enzyme activity over time by open circuit chronopotentiometry. The membrane biofunctionalization was accomplished by using a click chemistry protocol in addition to N-hydroxysuccinimide ester crosslinking and was characterized using confocal microscopy and electrochemical impedance spectroscopy. To demonstrate the principle, a choline-oxidase labelled antibody served as the detection reporter in a sandwich immunoassay for the determination of human lysozyme in saliva in the range of 10–100 μg mL−1 with a detection limit of 0.7 μg mL−1 (3σ). The enzyme-immunocomplex at the sensing surface catalyzes the oxidation of choline, an ion marker to which the membrane is selective and that is released from the membrane by a pulstrode protocol (galvanostatic pulse of 1 s duration and 10 μA magnitude). The enzyme turnover is interrogated by measuring the open circuit potential of the electrode over time after the release pulse. A model based on diffusion and enzyme kinetics is developed to rationalize the sensing principle and to guide the experiments. The results with this integrated immunosensor compare well to that of a conventional enzyme-linked immunoassay.

Synthesizing glycine betaine via choline oxidation pathway as an osmoprotectant strategy in Haloferacales

The accumulation of organic compatible solutes, such as glycine betaine, is one of the osmoprotective strategies used by halophilic archaea to adapt to high salinity. The uptake of glycine betaine from the external environment using various transporters has been widely studied in different halophilic archaea. However, the de novo biosynthesis of glycine betaine and its distribution in halophilic archaea remain unclear. In this study, an extremely halophilic archaea strain, named Halorubrum sp. 2020YC2 and previously isolated from a salt-lake sample, was identified with complete choline oxidation pathway genes. Halorubrum sp. 2020YC2 could synthesize and accumulate 1.56–4.25 μmol per mg of protein of glycine betaine in a defined medium, with its content increasing along with increasing salinity. The intracellular content of glycine betaine remained relatively stable at different salinities when another exogenous solute such as trehalose was provided. The metabolic profile and transcriptional results strongly suggested that the intracellular glycine betaine was derived from serine, which came from the glycolytic intermediate 3-phosphoglycerate when glucose was used as the sole carbon source. Out of 205 available genomes of halophilic archaea, genes encoding the choline oxidation pathway were identified in 30 genomes, and more than half of the strains belonging to order Haloferacales contained the choline oxidation pathway. Phylogenetic analysis further indicated that this pathway evolved from halophilic Proteobacteria, and its absence in some genera indicated a possible gene loss event during evolution. The analysis of reported culture data of halophilic archaea strains eventually demonstrated that the presence of the choline oxidation pathway had no significant effects on the adaptation of Haloferacales to high salinity habitats. Therefore, the de novo biosynthesis of glycine betaine via the choline oxidation pathway could be an auxiliary osmoprotective strategy in halophilic archaea.

Effects Of A Lifestyle Intervention On Trimethylamine N-oxide (tmao) Concentrations In Overweight And Obese Adults

PURPOSE: Trimethylamine N-Oxide (TMAO), a metabolite produced by gut microbiota and flavin-containing monooxygenase-3 (FMO3) of the liver, is found in foods high in carnitine, choline, and lecithin (e.g., egg yolks and full-fat dairy). The oxidation of choline that leads to betaine production also contributes to increased TMAO levels. Epidemiological studies have related TMAO concentrations to obesity and cardiovascular disease, yet few data exist on the effects of combined diet and exercise interventions on TMAO. METHODS: Twenty-six sedentary, overweight or obese adults (Age: 47.4 ± 10.7 yrs.; Weight: 95.1 ± 13.1 kg; BMI: 34.1 ± 3.2 kg/m2) completed a 10-week exercise and hypocaloric diet intervention to obtain clinically significant weight loss of ≥7%. Aerobic exercise volume began at 300 MET min per week and increased 50 MET min weekly until 700 MET min per week was reached. For 8 weeks, the OPTIFAST program included full meal replacement (~800 daily kcal). The last 2 weeks participants could replace 2 products with whole foods and increase intake (~1400 daily kcal). Weekly classes on behavior modification were also offered. Plasma blood samples were collected at baseline and follow-up and analyzed via nuclear magnetic resonance. RESULTS: At baseline, TMAO correlated with body weight (r = 0.40, p = 0.046), waist circumference (r = 0.40, p = 0.044), and RMR (r = 0.50, p = 0.009). Waist circumference (-7.6 cm), BMI (-3.1 kg/m2), body weight (-8.5 kg, -9.0%), total body fat (-1.7%), and triglycerides (-31.7 mg/dL) (all ps < 0.001) decreased following the intervention, however, there were no changes in TMAO (-0.3 μM, p = 0.292) or betaine (0.3 μM, p = 0.838) levels. Changes in TMAO were correlated with waist circumference (r = 0.50, p = 0.010), but not with change in body weight, body composition (lean mass, visceral mass, total fat mass), fitness, or cardiometabolic risk factors (all ps > 0.05), while changes in betaine were correlated with average RMR changes (r = -0.42, p = 0.037). CONCLUSIONS: Weight loss from a hypocaloric diet with aerobic exercise did not decrease TMAO, however, improvements in TMAO were associated with reductions in waist circumferenc in previously sedentary overweight and obese adults. Future studies should evaluate predictors of changes in TMAO during weight maintenance.

Consumption of a light meal affects serum concentrations of one-carbon metabolites and B-vitamins. A clinical intervention study.

The transfer of one-carbon units between molecules in metabolic pathways is essential for maintaining cellular homeostasis, but little is known about whether the circulating concentrations of metabolites involved in the one-carbon metabolism are affected by the prandial status. Epidemiological studies do not always consistently use fasting or non-fasting blood samples or may lack information on the prandial status of the study participants. Therefore, the main aim of the present study was to investigate the effects of a light breakfast on serum concentrations of selected metabolites and B-vitamins related to the one-carbon metabolism; i.e. the methionine-homocysteine cycle, the folate cycle, the choline oxidation pathway and the transsulfuration pathway. Sixty-three healthy adults (thirty-six women) with BMI ≥ 27 kg/m2 were included in the study. Blood was collected in the fasting state and 60 and 120 min after intake of a standardised breakfast consisting of white bread, margarine, white cheese, strawberry jam and orange juice (2218 kJ). The meal contained low amounts of choline, betaine, serine and vitamins B2, B3, B6, B9 and B12. Serum concentrations of total homocysteine, total cysteine, flavin mononucleotide, nicotinamide and pyridoxal 5'-phosphate were significantly decreased, and concentrations of choline, betaine, dimethylglycine, sarcosine, cystathionine and folate were significantly increased following breakfast intake (P < 0·05). Our findings demonstrate that the intake of a light breakfast with low nutrient content affected serum concentrations of several metabolites and B-vitamins related to the one-carbon metabolism.

Assessment of betaine content in commercial cow and goat milk

Betaine is a cytoplasmic osmolyte and a methyl group donor in many biochemical pathways. It exhibits numerous beneficial biological effects and has shown health benefits against some common chronic metabolic and degenerative diseases. In humans, it is obtained mostly from the diet, but it can also be endogenously synthesised by choline oxidation. Although betaine is a valuable human nutrient, information concerning its concentration in milk is still limited. Therefore, the aim of the present work was to quantify and compare the betaine content in commercial cow and goat milk. The betaine content was estimated using a simple isocratic HPLC-UV method following derivatisation with 4-bromophenacyl bromide. The sample pre-treatment included deproteinisation with 0.3% trifluoroacetic acid in acetonitrile. Betaine concentrations in cow milk ranged from 5.56 mg/L in milk with 0.5% fat, to 8.14 mg/L in milk with 2.8% fat. A positive but not significant relationship between fat and the betaine content in milk (r = 0.43) was observed. The average betaine concentration in commercial cow milk (7.21 mg/L) was in line with the results of previous studies. On the other hand, the average level of betaine in commercial goat milk was three times greater (22.82 mg/L). As far as the authors are aware, there are no published results of the betaine content in goat milk, and the present work is the first in this field. The present work demonstrated that the application of a simple and efficient sample pre-treatment and the HPLC-UV method for betaine determination allows for its successful quantification in milk.

The choline dehydrogenase BetA of Acinetobacter baumannii: a flavoprotein responsible for osmotic stress protection.

Acinetobacter baumannii is outstanding for its ability to cope with low water activities which significantly contributes to its persistence in hospital environments. The vast majority of bacteria are able to prevent loss of cellular water by amassing osmoactive compatible solutes or their precursors into the cytoplasm. One such precursor of an osmoprotectant is choline that is taken up from the environment and oxidized to the compatible solute glycine betaine. Here, we report the identification of the osmotic stress operon betIBA in A. baumannii. This operon encodes the choline oxidation pathway important for the production of the solute glycine betaine. The salt-sensitive phenotype of a betA deletion strain could not be rescued by addition of choline, which is consistent with the role of BetA in choline oxidation. We found that BetA is a choline dehydrogenase but also mediates in vitro the oxidation of glycine betaine aldehyde to glycine betaine. BetA was found to be associated with the membrane and to contain a flavin, indicative for BetA donating electrons into the respiratory chain. The choline dehydrogenase activity was not salt dependent but was stimulated by the compatible solute glutamate.

Electrochemical Sensor for Choline Based on Iron (III) Oxide and Functionalized Multi-Walled Carbon Nanotube at the Glassy Carbon Electrode Surface

Iron (III) oxide nanoparticle (Fe3O4NP) was synthesized via green route using Callistemon viminalis leaf extract. A composite of Fe3O4NP with functionalized multi-walled carbon nanotube (f-MWCNT) was then applied as glassy carbon electrode modifier to develop a choline sensor. Electrocatalytic oxidation of choline on nanocomposite modified electrode (GCE/f-MWCNT/Fe3O4NP) was studied by cyclic voltammetry while mechanism of electron transfer process during choline electrocatalytic oxidation was monitored by electrochemical impedance spectroscopy at fixed potential 0.5 V with frequencies between 100 kHz and 0.01 Hz. Active surface coverage area of choline, charge transfer coefficient and number of electron transferred were reported. Square wave voltammetry (SWV) was employed for the determination of choline over a linear concentration range of 24.3 - 215.6 μM. A sensitivity of 0.0244 μA/μM and 9.9 μM detection limit was found. The sensor was selective to choline (0.1 mM) in the presence of 100 mM and 0.1 mM ascorbic acid (AA) and dopamine (DA) respectively using SWV and chronoamperometry. The designed electrode was reproducible and stable. The sensor was successfully used for choline detection in choline dietary supplements with resultant good recoveries. The fabrication of the sensor was simple and cost-effective. Figure 1

Biomarkers and Fatty Fish Intake: A Randomized Controlled Trial in Norwegian Preschool Children.

ABSTRACTBackgroundBiomarkers such as omega-3 (n–3) PUFAs, urinary iodine concentration (UIC), 1-methylhistidine (1-MH), and trimethylamine N-oxide (TMAO) have been associated with fish intake in observational studies, but data from children in randomized controlled trials are limited.ObjectivesThe objective of this exploratory analysis was to investigate the effects of fatty fish intake compared with meat intake on various biomarkers in preschool children.MethodsWe randomly allocated (1:1) 232 children, aged 4 to 6 y, from 13 kindergartens. The children received lunch meals of either fatty fish (herring/mackerel) or meat (chicken/lamb/beef) 3 times a week for 16 wk. We analyzed 86 biomarkers in plasma (n = 207), serum (n = 195), RBCs (n = 211), urine (n = 200), and hair samples (n = 210). We measured the effects of the intervention on the normalized biomarker concentrations in linear mixed-effect regression models taking the clustering within the kindergartens into account. The results are presented as standardized effect sizes.ResultsWe found significant effects of the intervention on the following biomarkers: RBC EPA (20:5n–3), 0.61 (95% CI: 0.36, 0.86); DHA (22:6n–3), 0.43 (95% CI: 0.21, 0.66); total n–3 PUFAs, 0.41 (95% CI: 0.20, 0.64); n–3/n–6 ratio, 0.48 (95% CI: 0.24, 0.71); adrenic acid (22:4n–6, −0.65 (95% CI: −0.91, −0.40), arachidonic acid (20:4n–6), −0.54 (95% CI: −0.79, −0.28); total n–6 PUFAs, −0.31 (95% CI: −0.56, −0.06); UIC, 0.32 (95% CI: 0.052, 0.59); hair mercury, 0.83 (95% CI: 0.05, 1.05); and plasma 1-MH, −0.35 (95% CI: −0.61, −0.094).ConclusionsOf the 86 biomarkers, the strongest effect of fatty fish intake was on n–3 PUFAs, UIC, hair mercury, and plasma 1-MH. We observed no or limited effects on biomarkers related to micronutrient status, inflammation, or essential amino acid, choline oxidation, and tryptophan pathways.The trial was registered at clinicaltrials.gov (NCT02331667).

Electrochemical detection of choline at f-MWCNT/Fe3O4 nanocomposite modified glassy carbon electrode

Choline is employed as cholinergic activity marker in brain tissue in the field of clinical detection of diseases. Although, chromatographic methods and biosensors are the most commonly used techniques for choline detection, there is also an interest in exploring the efficacy of a cost effective non-enzyme based sensor for choline detection. Here, electrochemical sensors based on green synthesized metal oxides (iron (III) oxide nanoparticles) from Callistemon viminalis leaves and flowers extract (Fe3O4NPL and Fe3O4NPF) in combination of functionalized multi-walled carbon nanotube (f-MWCNT) supported on glassy carbon electrodes (GCE/f-MWCNT/Fe3O4NPL and GCE/f-MWCNT/Fe3O4NPF) were fabricated for choline detection. Morphological, structural and optical analysis of the nanocomposites were studied using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and ultra violet-visible (UV–vis) spectroscopy accordingly. In contrast, electron transport properties on bare glassy carbon electrode (GCE) and nanocomposite modified electrodes (GCE/f-MWCNT/Fe3O4NPL and GCE/f-MWCNT/Fe3O4NPF) was examined through electrochemical characterization using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Electrochemical oxidation of choline was also studied through CV, EIS, square wave voltammetry (SWV) and chronoamperometry (CA). The result proved that f-MWCNT enhanced the reactivity of Fe3O4NP towards choline oxidation with voltammetric limit of detection (0.83 and 0.36 μM) for choline at GCE/f-MWCNT/Fe3O4NPL and GCE/f-MWCNT/Fe3O4NPF electrodes respectively. Designed sensors proved selective, reproducible, stable and applicable for real sample sensing in choline dietary supplements.

Functional Expression of Choline Transporters in Human Neural Stem Cells and Its Link to Cell Proliferation, Cell Viability, and Neurite Outgrowth.

Choline and choline metabolites are essential for all cellular functions. They have also been reported to be crucial for neural development. In this work, we studied the functional characteristics of the choline uptake system in human neural stem cells (hNSCs). Additionally, we investigated the effect of extracellular choline uptake inhibition on the cellular activities in hNSCs. We found that the mRNAs and proteins of choline transporter-like protein 1 (CTL1) and CTL2 were expressed at high levels. Immunostaining showed that CTL1 and CTL2 were localized in the cell membrane and partly in the mitochondria, respectively. The uptake of extracellular choline was saturable and performed by a single uptake mechanism, which was Na+-independent and pH-dependent. We conclude that CTL1 is responsible for extracellular choline uptake, and CTL2 may uptake choline in the mitochondria and be involved in DNA methylation via choline oxidation. Extracellular choline uptake inhibition caused intracellular choline deficiency in hNSCs, which suppressed cell proliferation, cell viability, and neurite outgrowth. Our findings contribute to the understanding of the role of choline in neural development as well as the pathogenesis of various neurological diseases caused by choline deficiency or choline uptake impairment.

Exploring the potentials of betaine supplementation in poultry and pig: A review

The present review explores the nutritional and performance boosting functions of betaine in poultry and pig ration as a feed additive. Betaine, a trimethyl derivative of glycine is a normal metabolite in many plant and animal tissues. In all the animals, betaine is produced by oxidation of choline or supplied through feed. Its characteristics chemical structure makes betaine a dipolar zwitterion, conferring it osmoprotective and methyl donating properties. Over the past decades, numerous studies have investigated and published the favorable effects of betaine on performance in different animal species. Betaine is involved in transmethylation reactions for the synthesis of several metabolically active substances like creatine, carnitine etc. Also, it has shown evidence to increasing nutrient utilization, digestibility and methionine availability. Boosting immune status and reducing oxidative or heat stress are also some of the important functions of betaine. Most of the researches have specifically studied the growth promoting, carcass modulating, immune boosting or stress reducing properties of betaine in different species. Literature covering on different benefits of betaine as an essential feed supplement is not yet abundant. As both poultry and pig are important species of domesticated animals, betaine can be a better and cheaper, alternative feed supplement for enhancing the nutrient utilization and performance of poultry and pig. Therefore, an attempts have been made to delineate the functional effects of supplementary betaine in poultry and pig.

Electrochemical immunoassay based on choline oxidase-peroxidase enzymatic cascade

Horseradish peroxidase (HRP)-based electrochemical immunoassays are considered promising techniques for point-of-care clinical diagnostics, but the necessary addition of unstable H2O2 in the enzymatic system may hinder their practical application. Although glucose oxidase (GOx) has been widely explored for in situ generation of H2O2 in HRP-based immunoassay, the GOx-catalyzed reduction of oxidized peroxidase substrate may limit the immunosensing performance. Here, we report a sensitive electrochemical immunosensor based on a choline oxidase (ChOx)-HRP cascade reaction. In this design, ChOx catalyzes the oxidation of choline, during which H2O2 is generated in situ and thus oxidizes acetaminophen (APAP) in the presence of HRP. The electrochemical behavior of APAP in the ChOx-HRP cascade was compared with that of the commonly used GOx-HRP cascade, which confirmed that ChOx could be a superior preceding enzyme for sensitive immunoassay based on the bienzymatic cascade. The developed ChOx-HRP cascade was also further explored for a sandwich-type electrochemical immunoassay of parathyroid hormone in artificial and clinical serum. The calculated detection limit was ~3 pg/mL, indicating that the ChOx-HRP cascade is especially promising for highly sensitive electrochemical immunoassays when APAP is used as the peroxidase substrate.

Enhancement of interfacial catalysis in a triphase reactor using oxygen nanocarriers

Multiphase catalysis is used in many industrial processes; however, the reaction rate can be restricted by the low accessibility of gaseous reactants to the catalysts in water, especially for oxygen-dependent biocatalytic reactions. Despite the fact that solubility and diffusion rates of oxygen in many liquids (such as perfluorocarbon) are much higher than in water, multiphase reactions with a second liquid phase are still difficult to conduct, because the interaction efficiency between immiscible phases is extremely low. Herein, we report an efficient triphase biocatalytic system using oil core–silica shell oxygen nanocarriers. Such design offers the biocatalytic system an extremely large water-solid-oil triphase interfacial area and a short path required for oxygen diffusion. Moreover, the silica shell stabilizes the oil nanodroplets in water and prevents their aggregation. Using oxygen-dependent oxidase enzymatic reaction as an example, we demonstrate this efficient biocatalytic system for the oxidation of glucose, choline, lactate, and sucrose by substituting their corresponding oxidase counterparts. A rate enhancement by a factor of 10–30 is observed when the oxygen nanocarriers are introduced into reaction system. This strategy offers the opportunity to enhance the efficiency of other gaseous reactants involved in multiphase catalytic reactions.