Human Vitamin Research Articles

Inhibition of vitamin C transport impairs neuronal differentiation of hiPSCs

Vitamin C is an antioxidant that acts as a free radical scavenger and cofactor for many important biological reactions. It plays an important role in stem cell homeostasis, proliferation and differentiation. However, the role of vitamin C transporters in the neuronal differentiation of human induced pluripotent stem cells (hiPSCs) has not yet been investigated. Therefore, we investigated if vitamin C transporter knockdown impairs neuronal differentiation in hiPSCs. We differentiated hiPSCs into neurons from undifferentiated hiPSCs using established protocols and employed siRNA‐mediated knockdown experiments. Validation of results was performed by RT‐qPCR, Western blot analysis, RNA‐Sequencing (RNA‐Seq) and confocal imaging. First, we determined the expression of the human sodium‐dependent vitamin C transporters, hSVCT1 and hSVCT2 (products of the SLC23A1 and SLC23A2 genes, respectively) using RNA‐Seq analysis. RNA‐Seq analysis showed that both SLC23A1 and SLC23A2 were expressed during differentiation of neuronal hiPSCs. As expected, the immunofluorescence results showed that the hSVCT2 is predominantly expressed on the plasma membrane during neuronal hiPSCs differentiation. We validated the effectiveness of SLC23A1, SLC23A2and SCAMP2 (a vitamin C transporter interacting protein) knockdown by gene specific siRNA using RT‐qPCR analysis. RT‐qPCR analysis found that the expression of all three genes were significantly reduced. We also demonstrated that knockdown of SLC23A1, SLC23A2 and SCAMP2 was accompanied by a significant decrease in the number of Tuj‐1 (early neuron marker)‐positive cells during neuronal hiPSCs differentiation. Reciprocally, we demonstrated vitamin C supplementation dose‐dependently increases Tuj‐1 positive cells during neuronal hiPSCs differentiation. In conclusion, we demonstrate that knockdown of vitamin C transporter impairs neuronal differentiation of hiPSCs. These findings suggest that vitamin C and its transporters play an important role in neuronal differentiation, development, and function in hiPSCs.

Therapeutic potential of a combination of recombinant human growth hormone (r-hGH) and vitamin D in children with idiopathic short stature

Purpose: To study the effectiveness and clinical significance of recombinant human growth hormone (rhGH) in combination with vitamin D in the treatment of idiopathic short-stature children.Methods: A total of 90 idiopathic short-stature children admitted at Children Health Care Center of Shiyan Maternal and Child Health Care Hospital, Shiyan between March 2017 and March 2020 were assigned to three groups: A, B and C, based on dose of r-hGH given. Group A received r-hGH at a dose of 0.26 mg/kg/week, while groups B and C received r-hGH at doses of 0.35 and 0.42mg/kg/week, respectively. All the patients were given vitamin D along with the r-hGH doses administered. Height, growth rate, bone age, height standard deviation score, fasting blood glucose, thyroid function and treatment effectiveness were determined and compared among the three groups before treatment, and one year after treatment.Results: Significantly higher height standard deviation score, growth rate, bone age, and height were observed in the three groups of patients after one year of treatment than before treatment, with group A < group B < group C (p < 0.05). Fasting blood glucose and thyroid function were not significantly different amongst the three groups after treatment (p < 0.05). Group C showed the highest treatment effectiveness, followed by group B, and then group A (p < 0.05).Conclusion: The use of a combination of r-hGH and vitamin D produces a favorable treatment effectiveness in idiopathic short-stature children. However, further clinical trials are required to validate this treatment strategy.

Thiamine Deficiency in Children with Type I Diabetes Mellitus and Ketoacidosis Hospitalized in a Referral Pediatric Hospital in 2019 - 2020

Background: Thiamine is an essential coenzyme, reduced in type I and II diabetes. There has been little research on thiamine levels and their role in children with diabetic ketoacidosis (DKA). Objectives: This study aimed to analyze thiamine deficiency in this patient group. Methods: A cross-sectional study was done in 2019 - 2020 in Children’s Medical Center, a pediatric referral hospital with 350 beds, on children with type I diabetes hospitalized in the PICU for DKA. A blood sample was taken on admission to obtain biochemical laboratory parameters and measure electrolytes and thiamine levels. Blood gases were taken regularly, and the first pH and first bicarbonate level were measured. The time required for pH normalization and recovery from acidosis was recorded. Hospital stay duration was also calculated. Plasma thiamine measurement was done with a Human Vitamin B1 (VB1) ELISA Kit from Bioassay Technology Laboratory. Data were analyzed with SPSS version 22 software. Results: Of 62 patients, 56.5% were females with a mean age of 63 months. Thiamine level was 1.61 ± 1.17 μg/dL, and 66.1% of the patients were thiamine deficient. Hospitalization duration was 3.52 ± 0.41 days in the thiamine deficient group and 2.47 ± 0.32 days in the normal group (P value < 0.05). The white blood cell (WBC) count was higher in thiamine deficient patients. Thiamine levels were independently and inversely related to age. Conclusions: Thiamine deficiency is common among children with DKA and could be a prognostic and therapeutic factor.

The Importance of Vitamin D in Long-Term Care Residents

The Importance of Vitamin D in Long-Term Care Residents

Human Vitamin K Epoxide Reductase as a Target of Its Redox Protein.

Human vitamin K epoxide reductase (hVKORC1) enzymatic activity requires an initial activation by a specific redox protein, a less studied step in the hVKORC1 vital cycle. Significant steric conditions must be met by enzymes, being that to adapt their configurations is mandatory for hVKORC1 activation. We studied, by molecular dynamics (MD) simulations, the folding and conformational plasticity of hVKORC1 in its inactive (fully oxidised) state using available structures, crystallographic and from de novo modelling. According to the obtained results, hVKORC1 is a modular protein composed of the stable transmembrane domain (TMD) and intrinsically disordered luminal (L) loop, possessing the great plasticity/adaptability required to perform various steps of the activation process. The docking (HADDOCK) of Protein Disulfide Isomerase (PDI) onto different hVKORC1 conformations clearly indicated that the most interpretable solutions were found on the target closed L-loop form, a prevalent conformation of hVKORC1’s oxidised state. We also suggest that the cleaved L-loop is an appropriate entity to study hVKORC1 recognition/activation by its redox protein. Additionally, the application of hVKORC1 (membrane protein) in aqueous solution is likely to prove to be very useful in practice in either in silico studies or in vitro experiments.

Vitamin D status and its Association with Atherogenic Index of Plasma in Young Subjects with PCOS

Background-PCOS subjects often suffer from metabolic co-morbidities . Atherogenic Index of Plasma(AIP) is a reliable risk marker for CV disease. Vitamin D receptor gene regulates about 3% of the human genome and Vitamin D deficiency is considered to be involved in the pathogenesis of metabolic syndrome.

Role of human cartilage glycoprotein-39 and vitamin C in the development and clinical course of knee arthrosis in combination with coronary artery disease, hypertension, dyslipidemia, cholelithiasis

Aim. To study the role of human cartilage glycoprotein-39 (HC gp-39) and vitamin C in the development and clinical course of knee arthrosis (gonarthrosis) in combination with coronary artery disease (CAD), hypertension (HTN), dyslipidemia, cholelithiasis, depending on inflammatory changes in the joints, X-ray stage, pain intensity and the degree of joints’ functional impairment.Material and methods. We examined 140 patients with gonarthrosis in combination with CAD, HTN, dyslipidemia, cholelithiasis, who were treated in the rheumatology department of the North Ossetian State Medical Academy. In all patients, the main clinical parameters of gonarthrosis were assessed, and the content of HC gp-39, vitamin C, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and serum lipids was determined.Results. An increase in HC gp-39 levels was revealed in all examined patients. The highest rate of HC gp-39 was found in patients with X-ray stage III arthrosis, especially with reactive synovitis. A decrease in blood serum concentration of vitamin C was revealed depending on gonarthrosis stage. A significant correlation was noted between HC gp-39 level and main clinical indices of gonarthrosis, as well as CRP, ESR, cholesterol, atherogenic coefficient, and vitamin C.Conclusion. Changes in the levels of HC gp-39, vitamin C, CRP and lipid profile reflect the inflammation severity, which is an important component of the pathogenesis of osteoarthritis, atherosclerosis, and cholelithiasis.

Association of serum vitamin B12 with immuno-hematological parameters in treatment-naive HIV positive cases.

The manifestations of human immunodeficiency virus (HIV) infection and vitamin B12 deficiency overlap each other, so early diagnosis and intervention is important. The study aims to find out serum vitamin B12 level and its association with CD4 and CD8 count, clinical-staging, and hemato-biochemical status in newly diagnosed HIV positive cases. Fifty-five confirmed HIV cases above 18 years of age and equal number of age and sex matched controls were recruited for the study. CD4 and CD8 counts were analyzed by Flow cytometer. Complete Blood Count, Serum vitamin B12, Folic acid, ferritin, and C-Reactive Protein (CRP) concentration were done. Serum vitamin B12 was observed to be significantly low in HIV positive cases than healthy controls with a mean value of 240.62 ± 56.75 pg/ml and 317.57 ± 52.56 pg/ml, respectively. Decreased CD4 counts with elevated levels of ferritin and CRP was seen in HIV positive individuals. The subgroup analysis based on the levels of vitamin B12 was directly proportional to CD4 counts. CD8 counts also registered a significant association with serum B12 level, yet the response is not proportionate with the level of vitamin B12 deficiency. Nearly one-third of HIV positive cases revealed vitamin B12 deficiency. During the early stage, fast dividing immune cells cause increased consumption of micronutrients contributing toward vitamin B12 deficiency. It contributes to disorders in methylation affecting the immune function and NK Cell activity which increases the number of CD8 cells. Hence, vitamin B12 is a beneficial immunological modulator of HIV infection and can be a potent game changer in resource constrained set up.

Regulatory role and anticarcinogenic properties of certain vitamins' active derivatives and vitamin-like substances

Vitamins are low-molecular compounds consisting of an essential part of the human diet. After entering the human organism vitamins or their precursors can undergo chemical modification, changing their biological properties and regulatory activity. For many decades, vitamins were considered mainly as precursors of enzyme cofactors, and hypovitaminosis was interpreted as a deficiency of a particular metabolite resulting from enzyme's insufficient activity. However, with the development of molecular biology techniques and breakthrough in understanding of gene expression regulation and cell signaling mechanisms, as well as in molecular mechanisms of diseases associated with impaired functions, it became clear that there are significantly more active forms of vitamins, and their functions in the human body are more diverse than it had been suggested previously. The purpose of this review was to consider vitamins' and vitamins' derivatives regulatory and anti-tumor role and their potential for clinical application as main or adjuvant drugs for malignant neoplasms treatment. Material and methods. The present review is based on the results of literature analysis conducted in the Scopus, PubMed, Science Direct databases for the keywords «vitamin A AND cancer», «retinoids AND cancer», «vitamin D AND cancer», «vitamins AND cancer», «vitamins AND cancer». The search depth was 6 years (2016-2021). Results. Active forms of hydrophilic and lipophilic vitamins are key participants in the processes of chromatin remodeling, genome stability maintaining, covalent modification of proteins, including signaling and regulatory ones, and also act as chemical messengers themselves. Therefore, vitamin deficiency is associated with autoimmune and chronic diseases such as cancer, atherosclerosis, diabetes mellitus, etc. This review considers the regulatory role of active forms of vitamins, their derivatives and vitamin-like substances as well as their involvement in the process of carcinogenesis. Conclusions. Modern studies confirm the high therapeutic potential of vitamins: the use of pharmacological doses of vitamins or their derivatives may help to prevent or fight non-communicable diseases, including cancer.

Membrane Protein Production in the Yeast P. pastoris.

The first crystal structures of recombinant mammalian membrane proteins were solved using high-quality protein that had been produced in yeast cells. One of these, the rat Kv1.2 voltage-gated potassium channel, was synthesized in Pichia pastoris. Since then, this yeast species has remained a consistently popular choice of host for synthesizing eukaryotic membrane proteins because it is quick, easy, and cheap to culture and is capable of posttranslational modification. Very recent structures of recombinant membrane proteins produced in P. pastoris include a series of X-ray crystallography structures of the human vitamin K epoxide reductase and a cryo-electron microscopy structure of the TMEM206 proton-activated chloride channel from pufferfish. P. pastoris has also been used to structurally and functionally characterize a range of membrane proteins including tetraspanins, aquaporins, and G protein-coupled receptors. This chapter provides an overview of the methodological approaches underpinning these successes.

Survey of Vitamin D Deficiency and Associated Comorbidities in Lahore

Vitamin D is recognized for its importance in bone health along with the reduced risk of cardiovascular, autoimmune and several chronic diseases. Objectives: Present study was designed to explore the prevalence of vitamin D deficiency and its association with comorbidities (Type 2 Diabetes, Thyroid Disease, Hypertension, Asthma, Heart Disease, Gastritisand Osteoporosis) among the subjects visiting outpatient departments (OPDs) of public hospitals in Lahore. Methods: Adult (>18 years) male and female subjects (n = 200) participated in present cross-sectional study. Participating individuals were required to fill questionnaires which recorded their medical history and BMI. Blood samples were taken for laboratory evaluation of vitamin D3 deficiency. Data was analyzed for evaluation of diverse risk factors. Serum level of vitamin D3 (25-hydroxyvitamin D [25(OH)D3]) were measured using standard procedures of measurement using Human Vitamin D3 (VD3) ELISA Kit (MyBioSource, Inc. USA). Results: Vitamin D deficiency was more prevalent in females than in males. Of the 200 individuals, the highest number of patients suffered from Diabetes Myelitis Type-II (61%) followed by Thyroid Disease (38%). Whereas, the least number of vitamin D3 deficient subjects were suffering from Osteoporosis (5%).

Changes in Antioxidant Defence System in Durum Wheat under Hyperosmotic Stress: A Concise Overview.

Durum wheat is one of the most commonly cultivated species in the world and represents a key commodity for many areas worldwide, as its grain is used for production of many foods, such as pasta, bread, couscous, and bourghul. Durum wheat grain has a relevant role in the human diet, providing carbohydrates, proteins, lipids, fibres, vitamins, and minerals, as well as highly valued bioactive compounds contributing to a healthy diet. Durum wheat is largely cultivated in the Mediterranean basin, where it is mainly grown under rain-fed conditions, thus currently undergoing drought stress, as well as soil salinity, which can hamper yield potential and influence the qualitative characteristics of grain. When plants suffer drought and/or salinity stress, a condition known as hyperosmotic stress is established at cellular level. This leads to the accumulation of ROS thus generating in turn an oxidative stress condition, which can ultimately result in the impairment of cellular integrity and functionality. To counteract oxidative damage due to excessive ROS production under stress, plants have evolved a complex array of both enzymatic and non-enzymatic antioxidant mechanisms, working jointly and synergically for maintenance of ROS homeostasis. Enhancement of antioxidant defence system has been demonstrated as an adaptive mechanism associated to an increased tolerance to hyperosmotic stress. In the light of these considerations, this review provides a concise overview on recent advancements regarding the role of the ascorbate-glutathione cycle and the main antioxidant enzymes (superoxide dismutase, catalase, and peroxidases) in durum wheat response to drought and salt stresses that are expected to become more and more frequent due to the ongoing climate changes.

Potential Drug Candidates in Clinical Trials for the Treatment of Covid-19: An Updated Overview

The coronavirus (SARS-CoV-2) emerged in December 2019 in Wuhan, China and by the end of April 2020, it spread to more than 200 countries worldwide. Particularly the USA, Brazil, Spain, Italy, France, Germany, UK, Turkey, Iran, and Russia were the most affected countries till December 2020. Currently, most of the researchers are in a continuous struggle to develop a vaccine or new drugs to combat Covid-19. There are more than 30 drug candidates including Western medicines, natural products, and traditional Chinese medicines, that have shown to exhibit some efficacy against this highly infectious virus. This review encompasses the potential efficacy of some key drugs recently tested against Covid-19. With the rapid spread of Covid-19 reaching a new level every day, there is an immediate need to find safe and effective measures to diagnose, treat, mitigate, and combat the disease. Looking at the alarming dimensions that the disease is acquiring, treatment strategies among the different drug systems are being investigated. Currently, clinical management includes infection prevention, control measures, and supportive care, including supplemental oxygen and mechanical ventilation when indicated. The pharmaceutical interventions evaluated for the treatment of Covid-19 include human immunoglobulin, interferons, chloroquine, hydroxychloroquine, arbidol, remdesivir, oseltamivir, favipiravir, carrimycin, methylprednisolone, bevacizumab, thalidomide, vitamin C, pyrodfenidone, darthviravir, bromexistone, ryrexavir, lopinavir, xiyanping, and traditional Chinese medicine. But still, the researchers are struggling to discover the most effective drug for the treatment of the current pandemic of Covid-19. DOI: http://dx.doi.org/10.17807/orbital.v13i4.1638

Very preterm infants admitted to a tertiary neonatal unit in central Vietnam showed poor postnatal growth.

We aimed to evaluate the postnatal growth of very preterm infants. This was a cross-sectional observational study of neonates born before 32weeks of gestation and admitted to the neonatal unit at Da Nang Hospital for Women and Children, Vietnam, between 1 February 2020 and 30 September 2020.Morbidities, therapies, nutrition modalities and growth status were recorded from admission to discharge. The 78 infants (51% female) were born at a median of 29weeks and mean birth weight of 1247grams. The mean weight gain velocity from regaining their birth weight until discharge was 12.7±4.9g/kg/d. At discharge, the Z-scores for weight, length, both weight and length and weight for length were lower than at birth in 94%, 67%, 64% and 95% of infants and the Delta Z-scores were less than -1 in 73%, 44%, 39% and 82%. Late-onset sepsis (LOS) and bronchopulmonary dysplasia (BPD) were significantly associated with growth failure, with adjusted odds ratios of 3.6 and 20.1, respectively. The high rate of poor growth among the very preterm infants in our study indicates the need to reduce LOS and BPD and ensure the availability of human milk fortifier, vitamin and mineral supplements.

Transcriptomic and metabolomics of flavonoid compounds in Actinidia arguta var. arguta

Actinidia arguta (Sieb. et Zucc.) Planch ex Miq. is fruit plant with high added value, rich in bioactive compounds relevant for human health, like flavonoids and vitamin C, and has high antioxidant activity. These flavonoids also play important roles in plant immune responses and have strong medicinal implications. Moreover, it is very widely distributed in China and attracted more attention with great economic significance in recent years. However, the majority of research on flavonoids has been focused on fruit, not much has been elucidated in leaf in A. arguta. Whether are the leaves of Actinidia arguta also rich in flavonoids and other biologically active ingredients? The metabolome and transcriptome in fruits and leaves of A. arguta var. arguta cv. Changjiang No.1 (CJ-1) was analyzed in this study. We detected ten flavonoids in CJ-1 leaves that belonged to quercetin, isorhamnetin and kaempferol and using LC-MS/MS technology. Flavonoid quercetin were all detected in five tissues. Flavonoid qualification indicated that total flavonoids in young apical leaves were the highest (10219.84 µg·g−1) and 129.8 folds than in fruits (78.75 µg·g−1). From the transcriptome data, we obtained 70,631 non-redundant unigenes in total. There were 32,593 differentially expressed genes (DEGs) to be identified, including 29,617 up-regulated and 2976 down-regulated genes in fruits and young apical leaves. There were 127 metabolic pathways enriched with 3567 DEGs, in which 45 DEGs were associated with flavonoid biosynthesis. Next, the expression of qRT-PCR of key flavonoid pathway genes in leaves were higher than that in other tissues, which was consistent with the higher total flavonoid level. The data provided here were valuable for knowing the molecular mechanisms of flavonoids accumulating in different tissues. Our results were of significant contribution to the literature as they proposed possible new insights of applying leaves in A. arguta in the food and healthcare industries for their high content of flavonoids.

Porous silicon-mesoporous carbon nanocomposite based electrochemical sensor for sensitive and selective detection of ascorbic acid in real samples

Ascorbic acid (AA) is one of the vital water-soluble antioxidants in blood serum and can function as a key blood serum biomarker for oxidative stress. Therefore, we have developed a highly sensitive and selective AA electrochemical sensor based on novel porous silicon-mesoporous carbon nanocomposites (PSi-MC NCs) modified glassy carbon electrode (GCE). The structural properties and morphological investigation of the PSi-MC NCs were systematically studied by different techniques. This newly designed PSi-MC/GCE-based non-enzymatic electrochemical sensor can measure an extremely wide range of AA (0.5–2473 μM) in phosphate buffer solution (PBS) with a sensitivity 0.1982 μAμM−1cm−2 and a logical limit of detection (LOD) 30.0±0.1 nM. The proposed AA sensor was also applied to detect possible interference from common interfering substances that are present in human blood, showing highly selective performance. The proposed AA sensor also showed highly acceptable results towards the detection of AA levels in human blood serum and vitamin C tablets. This new combination of active material PSi-MC NCs provided steady, excellent reproducibility, repeatability, and long-term stability.

The technology of functional bakery cookies with fructose and food fibers

In Ukraine, the number of socially conditioned diseases, such as diabetes and obesity, has increased sharply in recent years, which is influenced by excessive consumption of easily digestible carbohydrates. The most important factor in the health of the population is nutrition and intensity of lifestyle. The human diet should include fiber, hemicellulose, pectin, gums, which are physiologically important components of food that prevent many human diseases, including due to deteriorating environmental conditions, increasing the number of stressful situations, reduced immunity to many pathogens diseases. The quality and technology of flour confectionery depends on the quality and functional properties of raw materials. Products of processing cereals, fruits and vegetables are sources of physiologically necessary for the functioning of the human body proteins, vitamins, minerals and dietary fiber. The development of functional foods with high nutritional value and the creation of ways to improve the structure of nutrition in general will affect the further development of technologies for foods with high nutritional value and low glycemic index. It is possible to prevent a rapid increase in blood glucose levels through the use of raw materials enriched with dietary fiber. The main problem in our country is to provide the population with useful food products that meet the physiological needs of the body and ensure physical health and active work. The article considers the topicality and development of technologies of functional shortbread cookies with low glycemic index using fiber and fructose. Organoleptic, technological and physicochemical studies were conducted, which proved the feasibility of replacing wheat flour and sugar in the developed technology. In the process of technological development, taking into account the organoleptic evaluation, a prototype was selected and the technology of shortbread cookies "Crispy" with partial replacement of flour and sugar with fiber and fructose, respectively. In determining the rational concentration of fiber and fructose in the partial replacement of flour and sugar in the technology of shortbread cookies, technological processing of recipes and studied the organoleptic characteristics of the model compositions. The quality of finished culinary products is characterized by organoleptic, physicochemical, biological and microbiological indicators, and a comprehensive quality indicator is used for the overall assessment. Calculating the quality indicators of shortbread cookies "Crispy", the following indicators were selected: organoleptic evaluation, content of proteins, fats, carbohydrates, mineral and vitamin composition, dietary fiber and energy value. According to the results of the research, the technology of functional shortbread cookies with high content of dietary fiber, reduced amount of mono- and disaccharides was developed. The developed confectionery can be recommended for food in the daily diets of people working in heavy industry, living in environmentally contaminated areas and all segments of the population, as well as to meet consumer demand for functional foods. Social efficiency is to expand the range of low-sugar flour confectionery using the sweetener fructose and wheat germ fiber. Key words: technology, nutritional value, confectionery, functional cookies, fiber, wheat germ, grape seeds, fructose.

Improving the bioavailability of oil-soluble vitamins by optimizing food matrix effects: A review

The potency of oil-soluble vitamins (vitamins A, D, E and K) in fortified foods can be improved by understanding how food matrices impact their bioavailability. In this review, the major food matrix effects influencing the bioavailability of oil-soluble vitamins are highlighted: oil content, oil composition, particle size, interfacial properties, and food additives. Droplet size and aggregation state in the human gut impact vitamin bioavailability by modulating lipid digestion, vitamin release, and vitamin solubilization. Vitamins in small isolated oil droplets typically have a higher bioavailability than those in large or aggregated ones. Emulsifiers, stabilizers, or texture modifiers can therefore affect bioavailability by influencing droplet size or aggregation. The dimensions of the hydrophobic domains in mixed micelles depends on lipid type: if the domains are too small, vitamin bioavailability is low. Overall, this review highlights the importance of carefully designing food matrices to improve vitamin bioavailability.

Identification of the Primary Factors Determining theSpecificity of Human VKORC1 Recognition by Thioredoxin-Fold Proteins.

Redox (reduction–oxidation) reactions control many important biological processes in all organisms, both prokaryotes and eukaryotes. This reaction is usually accomplished by canonical disulphide-based pathways involving a donor enzyme that reduces the oxidised cysteine residues of a target protein, resulting in the cleavage of its disulphide bonds. Focusing on human vitamin K epoxide reductase (hVKORC1) as a target and on four redoxins (protein disulphide isomerase (PDI), endoplasmic reticulum oxidoreductase (ERp18), thioredoxin-related transmembrane protein 1 (Tmx1) and thioredoxin-related transmembrane protein 4 (Tmx4)) as the most probable reducers of VKORC1, a comparative in-silico analysis that concentrates on the similarity and divergence of redoxins in their sequence, secondary and tertiary structure, dynamics, intraprotein interactions and composition of the surface exposed to the target is provided. Similarly, hVKORC1 is analysed in its native state, where two pairs of cysteine residues are covalently linked, forming two disulphide bridges, as a target for Trx-fold proteins. Such analysis is used to derive the putative recognition/binding sites on each isolated protein, and PDI is suggested as the most probable hVKORC1 partner. By probing the alternative orientation of PDI with respect to hVKORC1, the functionally related noncovalent complex formed by hVKORC1 and PDI was found, which is proposed to be a first precursor to probe thiol–disulphide exchange reactions between PDI and hVKORC1.

Vitamin E catabolism in women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase, nonrandomized crossover study

Human vitamin E (α-tocopherol) catabolism is a mechanism for regulating whole-body α-tocopherol. To determine the roles of the intestine and liver on α-tocopherol catabolism as affected by fat or fasting, 2 deuterium-labeled (intravenous d6- and oral d3-) forms of α-tocopherol were used. Healthy women received intravenous d6-α-tocopherol and consumed d3-α-tocopherol with a 600-kcal defined liquid meal (DLM; 40% or 0% fat, n=10) followed by controlled meals; or the 0% fat DLM (n=7) followed by a 12-h fast (0% fat-fast), then controlled meals ≤72 h. The order of the 3-phase crossover design was not randomized and there was no blinding. Samples were analyzed by LC/MS to determine the α-tocopherol catabolites and α-carboxyethyl hydroxychromanol (α-CEHC) in urine, feces, and plasma that were catabolized from administered oral d3- and intravenous d6-α-tocopherols. Urinary and plasma d3- and d6-α-CEHC concentrations varied differently with the interventions. Mean±SEM cumulative urinary d6-α-CEHC derived from the intravenous dose excreted over 72 h during the 40% fat (2.50±0.37 μmol/g creatinine) and 0% fat (2.37±0.37 μmol/g creatinine) interventions were similar, but a ∼50% decrease was observed during the 0% fat-fast (1.05±0.39 μmol/g creatinine) intervention (compared with 0% fat, P=0.0005). Cumulative urinary d3-α-CEHC excretion was not significantly changed by any intervention. Total urinary and fecal excretion of catabolites accounted for <5% of each of the administered doses. Differential catabolism of the intravenous d6-α-tocopherol and oral d3-α-tocopherol doses shows both liver and intestine have roles in α-tocopherol catabolism. During the 40% fat intervention, >90% of urinary d3-α-CEHC excretion was estimated to be liver-derived, whereas during fasting <50% was from the liver with the remainder from the intestine, suggesting that there was increased intestinal α-tocopherol catabolism while d3-α-tocopherol was retained in the intestine in the absence of adequate fat/food for α-tocopherol absorption.This trial was registered at clinicaltrials.gov as NCT00862433.