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Walsh DJ, Bernard DJ, Fiddler JL, Pangilinan F, Esposito M, Harold D, Field MS, Parle-McDermott A, Brody LC. Vitamin B12 status and folic acid supplementation influence mitochondrial heteroplasmy levels in mice. PNAS NEXUS 2024; 3:pgae116. [PMID: 38560530 PMCID: PMC10978065 DOI: 10.1093/pnasnexus/pgae116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 02/29/2024] [Indexed: 04/04/2024]
Abstract
One-carbon metabolism is a complex network of metabolic reactions that are essential for cellular function including DNA synthesis. Vitamin B12 and folate are micronutrients that are utilized in this pathway and their deficiency can result in the perturbation of one-carbon metabolism and subsequent perturbations in DNA replication and repair. This effect has been well characterized in nuclear DNA but to date, mitochondrial DNA (mtDNA) has not been investigated extensively. Mitochondrial variants have been associated with several inherited and age-related disease states; therefore, the study of factors that impact heteroplasmy are important for advancing our understanding of the mitochondrial genome's impact on human health. Heteroplasmy studies require robust and efficient mitochondrial DNA enrichment to carry out in-depth mtDNA sequencing. Many of the current methods for mtDNA enrichment can introduce biases and false-positive results. Here, we use a method that overcomes these limitations and have applied it to assess mitochondrial heteroplasmy in mouse models of altered one-carbon metabolism. Vitamin B12 deficiency was found to cause increased levels of mitochondrial DNA heteroplasmy across all tissues that were investigated. Folic acid supplementation also contributed to elevated mitochondrial DNA heteroplasmy across all mouse tissues investigated. Heteroplasmy analysis of human data from the Framingham Heart Study suggested a potential sex-specific effect of folate and vitamin B12 status on mitochondrial heteroplasmy. This is a novel relationship that may have broader consequences for our understanding of one-carbon metabolism, mitochondrial-related disease and the influence of nutrients on DNA mutation rates.
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Affiliation(s)
- Darren J Walsh
- Gene and Environment Interaction Section, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
- School of Biotechnology, Dublin City University, Dublin 9, Ireland
| | - David J Bernard
- Gene and Environment Interaction Section, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Joanna L Fiddler
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14850, USA
- Department of Food, Nutrition, and Packaging Sciences, Clemson University, Clemson, SC 29634, USA
| | - Faith Pangilinan
- Gene and Environment Interaction Section, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Madison Esposito
- Gene and Environment Interaction Section, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Denise Harold
- School of Biotechnology, Dublin City University, Dublin 9, Ireland
| | - Martha S Field
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14850, USA
| | | | - Lawrence C Brody
- Gene and Environment Interaction Section, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
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2
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Halczuk K, Kaźmierczak-Barańska J, Karwowski BT, Karmańska A, Cieślak M. Vitamin B12-Multifaceted In Vivo Functions and In Vitro Applications. Nutrients 2023; 15:2734. [PMID: 37375638 DOI: 10.3390/nu15122734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/01/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Vitamin B12 plays a key role in DNA stability. Research indicates that vitamin B12 deficiency leads to indirect DNA damage, and vitamin B12 supplementation may reverse this effect. Vitamin B12 acts as a cofactor for enzymes such as methionine synthase and methylmalonyl-CoA mutase, which are involved in DNA methylation and nucleotide synthesis. These processes are essential for DNA replication and transcription, and any impairment can result in genetic instability. In addition, vitamin B12 has antioxidant properties that help protect DNA from damage caused by reactive oxygen species. This protection is achieved by scavenging free radicals and reducing oxidative stress. In addition to their protective functions, cobalamins can also generate DNA-damaging radicals in vitro that can be useful in scientific research. Research is also being conducted on the use of vitamin B12 in medicine as vectors for xenobiotics. In summary, vitamin B12 is an essential micronutrient that plays a vital role in DNA stability. It acts as a cofactor for enzymes involved in the synthesis of nucleotides, has antioxidant properties and has potential value as a generator of DNA-damaging radicals and drug transporters.
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Affiliation(s)
- Krzysztof Halczuk
- Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland
| | - Julia Kaźmierczak-Barańska
- Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland
| | - Bolesław T Karwowski
- Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland
| | - Aleksandra Karmańska
- Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland
| | - Marcin Cieślak
- Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland
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3
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Firat CK, Ozkan BN, Guler EM. Beneficial effects of vitamin B 12 treatment in pediatric patients diagnosed with vitamin B 12 deficiency regarding total-native thiol, oxidative stress, and mononuclear leukocyte DNA damage. Free Radic Res 2022; 56:631-639. [PMID: 36571212 DOI: 10.1080/10715762.2022.2162392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vitamin B12 is involved in biochemical metabolic pathways. B12 deficiency is common in childhood when the need for the vitamin increases and growth and development occur. Various hematological, neurological, psychiatric, and gastrointestinal disorders are observed in its deficiency. In addition, B12 deficiency is associated with oxidative stress and DNA damage. Therefore, the aim of our study is to evaluate oxidative stress, thiol/disulfide homeostasis, and DNA damage pre and post-treatment in children diagnosed with B12 deficiency. A total of 40 children with B12 deficiency were included in the study after the consent form was approved. Blood was drawn from children pre and posttreatment. Hemoglobin (HGB), hematocrit (HCT), and red blood cells (RBC) were measured by autoanalyzer; total antioxidant status (TAS), total oxidant status (TOS), total thiol (TT), and native thiol (NT) were measured by the photometric method, and DNA damage was analyzed by the comet assay method. Oxidative stress index (OSI) and disulfide (DIS) values were calculated. As a result of the experiments, HGB, HCT, and RBC increased with treatment. While TAS, TT, and NT as antioxidant parameters increased; TOS, OSI, and DIS decreased with treatment compared to pretreatment. DNA damage was also found to decrease with treatment. Additionally, these data were statistically significant (p < 0.001). It was found that oxidative stress and DNA damage decreased with oral B12 treatment in children with B12 deficiency, and clinical parameters were also improved.
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Affiliation(s)
- Cem Koray Firat
- Department of Pediatry, Bezmialem Vakif University School of Medicine, Istanbul, Turkey
| | - Beyza Nur Ozkan
- Department of Medical Biochemistry, University of Health Sciences Turkey, Hamidiye School of Medicine, Istanbul, Turkey
| | - Eray Metin Guler
- Department of Medical Biochemistry, University of Health Sciences Turkey, Hamidiye School of Medicine, Istanbul, Turkey.,Department of Medical Biochemistry, University of Health Sciences Turkey, Hamidiye Faculty of Medicine, Haydarpasa Numune Health Application and Research Center, Istanbul, Turkey
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4
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The frequency of vitamin B12, iron, and folic acid deficiency in the neonatal period and infancy, and the relationship with maternal levels. Turk Arch Pediatr 2020; 55:139-148. [PMID: 32684759 PMCID: PMC7344137 DOI: 10.14744/turkpediatriars.2020.14042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Indexed: 12/16/2022]
Abstract
Aim: The most important function of vitamin B12 is to accomplish DNA synthesis, which is necessary for cell division and proliferation. Deficiency of vitamin B12 causes megaloblastic anemia, retardation of growth, and delay in neuromotor maturation. Newborns whose mothers have vitamin B12 deficiency are born with low vitamin B12 storages, and are at risk in terms of vitamin B12 deficiency symptoms during infancy. The aim of our study was to investigate the frequency of anemia and deficiency of vitamin B12, folic acid, and iron in pregnant women living in our region, in their newborn babies, and during the infancy period of these babies. Another aim of our study was to investigate the correlation between the levels of these vitamins in newborns and in their mothers. Material and Methods: In our study, 250 pregnant women at 38–42 gestational weeks, who were admitted for delivery to Gynecology and Obstetrics Clinic and their babies with a birth weight over 2500 g were included in the study. Results: We determined that 24.8% of the pregnant women had anemia, 28% had low ferritin levels, 90.4% had vitamin B 12 deficiency, and 22.4% had folic acid deficiency. Some 3.2% of the newborns had anemia, 2.8% had low ferritin levels, and 72.4% had vitamin B12 deficiency. Among the infants who presented for a follow-up visit at 6 months of age, 22.3% had anemia, 14.9% had low ferritin levels, 40.4% had vitamin B12 deficiency, and 1.06% had folic acid deficiency. In addition, we found that the levels of vitamin B12 and folic acid in newborns were related to the levels of vitamin B12 and folic acid in their mothers. Conclusion: Development of low vitamin B12 stores in newborns and the development of vitamin B12 deficiency during infancy, which may result in irreversible complications including neurologic complications, can be prevented by preventing vitamin B12 deficiency during pregnancy.
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K W, J O, P P, K DG, K K, M Z, M B, M S. Residential exposure to radon and levels of histone γH2AX and DNA damage in peripheral blood lymphocytes of residents of Kowary city regions (Poland). CHEMOSPHERE 2020; 247:125748. [PMID: 31954338 DOI: 10.1016/j.chemosphere.2019.125748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 06/10/2023]
Abstract
INTRODUCTION Radon-induced biological effects have been studied mainly through epidemiological investigations, and well-controlled in vitro and in vivo experiments. To provide data explaining radon exposure-induced harmful effects in natural environment, exposure assessment under these conditions is needed. The objective of the study was to examine the level of genetic damage assessed with biomarkers of DNA single- and double-strand breaks (SSBs and DSBs) in peripheral blood mononuclear cells obtained from individuals continuously exposed to Rn in homes. Naturally elevated Rn concentrations in homes can be found in the South of Poland, in Kowary city. METHODS Measurements of expression of phosphorylated histone γH2AX was used as a marker of DNA double strand breaks. To detect DNA single and double-strand breaks and alkali labile sites, the alkaline comet assay was used. Oxidative damage of DNA was evaluated by formamidopyrimidyne (FPG)-modified comet assay. The blood was collected from 94 volunteers living in Kowary. Subjects were grouped according to their status of living in radon concentration ≥100 Bq/m3 (n = 67), and <100 Bq/m3 (n = 27). RESULTS The statistically significant differences in levels of DNA damage in peripheral lymphocytes assessed with comet assay were found to be associated with levels of radon exposure in indoor air (p = 0.034). DNA damage in the comet assay was significantly correlated with DNA damage assessed with γH2AX staining. CONCLUSIONS Results of the present study indicate the suitability of alkaline comet assay for the detection of DNA damage in peripheral blood lymphocytes of people environmentally exposed to radon.
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Affiliation(s)
- Walczak K
- Radiological Protection Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland.
| | - Olszewski J
- Radiological Protection Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Politański P
- Radiological Protection Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Domeradzka-Gajda K
- Toxicology and Carcinogenesis Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Kowalczyk K
- Toxicology and Carcinogenesis Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Zmyślony M
- Radiological Protection Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Brodecki M
- Radiological Protection Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
| | - Stępnik M
- Toxicology and Carcinogenesis Dept, Nofer Institute of Occupational Medicine, ul. Św. Teresy od Dzieciątka Jezus 8, 91-348, Łódź, Poland
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Contestabile R, di Salvo ML, Bunik V, Tramonti A, Vernì F. The multifaceted role of vitamin B 6 in cancer: Drosophila as a model system to investigate DNA damage. Open Biol 2020; 10:200034. [PMID: 32208818 PMCID: PMC7125957 DOI: 10.1098/rsob.200034] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A perturbed uptake of micronutrients, such as minerals and vitamins, impacts on different human diseases, including cancer and neurological disorders. Several data converge towards a crucial role played by many micronutrients in genome integrity maintenance and in the establishment of a correct DNA methylation pattern. Failure in the proper accomplishment of these processes accelerates senescence and increases the risk of developing cancer, by promoting the formation of chromosome aberrations and deregulating the expression of oncogenes. Here, the main recent evidence regarding the impact of some B vitamins on DNA damage and cancer is summarized, providing an integrated and updated analysis, mainly centred on vitamin B6. In many cases, it is difficult to finely predict the optimal vitamin rate that is able to protect against DNA damage, as this can be influenced by a given individual's genotype. For this purpose, a precious resort is represented by model organisms which allow limitations imposed by more complex systems to be overcome. In this review, we show that Drosophila can be a useful model to deeply understand mechanisms underlying the relationship between vitamin B6 and genome integrity.
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Affiliation(s)
- Roberto Contestabile
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy
| | - Martino Luigi di Salvo
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy
| | - Victoria Bunik
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia.,Sechenov Medical University, Sechenov University, 119048 Moscow, Russia
| | - Angela Tramonti
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy.,Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Pl.e A. Moro, 5, 00185 Roma, Italy
| | - Fiammetta Vernì
- Dipartimento di Biologia e Biotecnologie 'Charles Darwin', Sapienza Università di Roma, Pl.e A. Moro, 5, 00185 Roma, Italy
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7
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Mohsenzadegan M, Kourosh Arami M, Oshaghi M, Sedigh Maroufi S. A review of the effects of the anesthetic gas nitrous oxide on the immune system; a starting point for future experiences. Immunopharmacol Immunotoxicol 2020; 42:179-186. [PMID: 32131654 DOI: 10.1080/08923973.2020.1735412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nitrous oxide is a common gas used as an anesthetic agent and analgesic medication in operating rooms. The gas inhibits vitamin B12 dependent-methionine synthase, which converts L-homocysteine and 5-methyltetrahydrofolate to L-methionine and tetrahydrofolate, respectively, via a methylation process. The immune system has been frequently reported to be suppressed in anesthetized subjects during the postoperative period. Although previous reviews have focused on the pathophysiologic role of nitrous oxide, none of them has considered the harmful effects of nitrous oxide on the Defense system of the host. In this article, the authors review current studies on the effects of nitrous oxide on the immune system of both patients undergoing surgery and occupational exposure, as well as preclinical studies. Moreover, this paper opens a new horizon for future studies in the context of underlying mechanisms of nitrous oxide actions on the immune system.
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Affiliation(s)
- Monireh Mohsenzadegan
- Department of Medical Laboratory Science, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Masoumeh Kourosh Arami
- Department of Basic Sciences, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mojgan Oshaghi
- Department of Medical Laboratory Science, Faculty of Allied Medical Sciences, Iran University of Medical Sciences, Tehran, Iran
| | - Shahnam Sedigh Maroufi
- Department of Anesthetics, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
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8
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Determination of Lymphocyte Cytokinesis-Block Micronucleus Values in Apparently Healthy Children by means of Age and Sex. BIOMED RESEARCH INTERNATIONAL 2019; 2019:8729561. [PMID: 31950057 PMCID: PMC6944958 DOI: 10.1155/2019/8729561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/12/2019] [Accepted: 11/25/2019] [Indexed: 11/18/2022]
Abstract
The cytokinesis-block micronucleus (MN) assay on blood lymphocytes is one of the most important tests implemented in cytogenetics for the measurement of genotoxicity. For the purpose of biological dosing, it is crucial to know the spontaneous frequency of MN and its normal values in general population, especially in children, which are used for the population databases. In this study, MN levels were investigated in cytokinesis-blocked lymphocytes of 150 apparently healthy children aged 1 to 15. Our aim was to assess the variability of MN values according to age and sex. The mean MN frequency among boys was 3.69 ± 1.747‰ and 4.12 ± 1.867‰ in girls where there was no significant difference in relation to age and sex. However, when we separated age groups as 0–2 years, 3–5 years, 6–10 years, and 11–15 years, one-way ANOVA test showed significant association. Significance was obvious in the 0–2 years age group with the 3–5 years age group and 6–10 years age group. When we grouped our study population as 0–2 years and 3–15 years, the mean MN frequency among the 0–2 years age group was 2.85 ± 1.599‰ and 4.07 ± 1.867‰ in the 3–15 years age group which was also statistically significant. This difference may be attributed to age-related increase of close contact with environmental hazardous agents. In conclusion, normal values of MN obtained in this study will add valuable information in regard to update the current childhood population data and will act as a reference for further genotoxicity studies.
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Reinson K, Künnapas K, Kriisa A, Vals MA, Muru K, Õunap K. High incidence of low vitamin B12 levels in Estonian newborns. Mol Genet Metab Rep 2018; 15:1-5. [PMID: 29387561 PMCID: PMC5772002 DOI: 10.1016/j.ymgmr.2017.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/05/2017] [Accepted: 11/05/2017] [Indexed: 11/04/2022] Open
Abstract
Vitamin B12 deficiency seems to be more common worldwide than previously thought. However, only a few reports based on data from newborn screening (NBS) programs have drawn attention to that subject. In Estonia, over the past three years, we have diagnosed 14 newborns with congenital acquired vitamin B12 deficiency. Therefore, the incidence of that condition is 33.8/100,000 live births, which is considerably more than previously believed. None of the newborns had any clinical symptoms associated with vitamin B12 deficiency before the treatment, and all biochemical markers normalized after treatment, which strongly supports the presence of treatable congenital deficiency of vitamin B12. During the screening period, we began using actively ratios of some metabolites like propionylcarnitine (C3) to acetylcarnitine (C2) and C3 to palmitoylcarnitine (C16) to improve the identification of newborns with acquired vitamin B12 deficiency. In the light of the results obtained, we will continue to screen the congenital acquired vitamin B12 deficiency among our NBS program. Every child with aberrant C3, C3/C2 and C3/C16 will be thoroughly examined to exclude acquired vitamin B12 deficiency, which can easily be corrected in most cases.
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Affiliation(s)
- Karit Reinson
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
| | - Kadi Künnapas
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
| | - Annika Kriisa
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
| | - Mari-Anne Vals
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Children's Clinic, Tartu University Hospital, Tartu, Estonia
| | - Kai Muru
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
| | - Katrin Õunap
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
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10
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Folate rescues vitamin B 12 depletion-induced inhibition of nuclear thymidylate biosynthesis and genome instability. Proc Natl Acad Sci U S A 2017; 114:E4095-E4102. [PMID: 28461497 DOI: 10.1073/pnas.1619582114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Clinical vitamin B12 deficiency can result in megaloblastic anemia, which results from the inhibition of DNA synthesis by trapping folate cofactors in the form of 5-methyltetrahydrofolate (5-methylTHF) and subsequent inhibition of de novo thymidylate (dTMP) biosynthesis. In the cytosol, vitamin B12 functions in the remethylation of homocysteine to methionine, which regenerates THF from 5-methylTHF. In the nucleus, THF is required for de novo dTMP biosynthesis, but it is not understood how 5-methylTHF accumulation in the cytosol impairs nuclear dTMP biosynthesis. The impact of vitamin B12 depletion on nuclear de novo dTMP biosynthesis was investigated in methionine synthase-null human fibroblast and nitrous oxide-treated HeLa cell models. The nucleus was the most sensitive cellular compartment to 5-methylTHF accumulation, with levels increasing greater than fourfold. Vitamin B12 depletion decreased de novo dTMP biosynthesis capacity by 5-35%, whereas de novo purine synthesis, which occurs in the cytosol, was not affected. Phosphorylated histone H2AX (γH2AX), a marker of DNA double-strand breaks, was increased in vitamin B12 depletion, and this effect was exacerbated by folate depletion. These studies also revealed that 5-formylTHF, a slow, tight-binding inhibitor of serine hydroxymethyltransferase (SHMT), was enriched in nuclei, accounting for 35% of folate cofactors, explaining previous observations that nuclear SHMT is not a robust source of one-carbons for de novo dTMP biosynthesis. These findings indicate that a nuclear 5-methylTHF trap occurs in vitamin B12 depletion, which suppresses de novo dTMP biosynthesis and causes DNA damage, accounting for the pathophysiology of megaloblastic anemia observed in vitamin B12 and folate deficiency.
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Abstract
Vitamin B-12 deficiency (<148 pmol/L) is associated with adverse maternal and neonatal outcomes, including developmental anomalies, spontaneous abortions, preeclampsia, and low birth weight (<2500 g). The importance of adequate vitamin B-12 status periconceptionally and during pregnancy cannot be overemphasized, given its fundamental role in neural myelination, brain development, and growth. Infants born to vitamin B-12-deficient women may be at increased risk of neural tube closure defects, and maternal vitamin B-12 insufficiency (<200 pmol/L) can impair infant growth, psychomotor function, and brain development, which may be irreversible. However, the underlying causal mechanisms are unknown. This review was conducted to examine the evidence that links maternal vitamin B-12 status and perinatal outcomes. Despite the high prevalence of vitamin B-12 deficiency and associated risk of pregnancy complications, few prospective studies and, to our knowledge, only 1 randomized trial have examined the effects of vitamin B-12 supplementation during pregnancy. The role of vitamin B-12 in the etiology of adverse perinatal outcomes needs to be elucidated to inform public health interventions.
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Affiliation(s)
- Julia L Finkelstein
- Division of Nutritional Sciences, Cornell University, Ithaca, NY; and St. John's Research Institute, St. John's National Academy of Health Sciences, Bangalore, India
| | | | - Patrick J Stover
- Division of Nutritional Sciences, Cornell University, Ithaca, NY; and
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12
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Milne E, Greenop KR, Ramankutty P, Miller M, de Klerk NH, Armstrong BK, Almond T, O'Callaghan NJ, Fenech M. Blood micronutrients and DNA damage in children. Mol Nutr Food Res 2015. [DOI: 10.1002/mnfr.201500110] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Elizabeth Milne
- Telethon Kids Institute; University of Western Australia; Perth Western Australia Australia
| | - Kathryn R. Greenop
- Telethon Kids Institute; University of Western Australia; Perth Western Australia Australia
| | - Padmaja Ramankutty
- Telethon Kids Institute; University of Western Australia; Perth Western Australia Australia
| | - Margaret Miller
- Child Health Promotion Research Centre; Edith Cowan University; Perth Western Australia Australia
| | - Nicholas H. de Klerk
- Telethon Kids Institute; University of Western Australia; Perth Western Australia Australia
| | - Bruce K. Armstrong
- Sydney School of Public Health; University of Sydney; Sydney New South Wales Australia
- Research Assets Division, Sax Institute; Sydney New South Wales Australia
| | - Theodora Almond
- Food and Nutrition Flagship; Commonwealth Scientific and Industrial Research Organization (CSIRO); Adelaide South Australia Australia
| | - Nathan J. O'Callaghan
- Food and Nutrition Flagship; Commonwealth Scientific and Industrial Research Organization (CSIRO); Adelaide South Australia Australia
| | - Michael Fenech
- Food and Nutrition Flagship; Commonwealth Scientific and Industrial Research Organization (CSIRO); Adelaide South Australia Australia
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13
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Ozdemir ZC, Koc A, Aycicek A, Kocyigit A. N-Acetylcysteine Supplementation Reduces Oxidative Stress and DNA Damage in Children with β-Thalassemia. Hemoglobin 2014; 38:359-64. [DOI: 10.3109/03630269.2014.951890] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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14
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Abstract
Abstract
Background:
Nitrous oxide inactivates methionine synthase and may lead to DNA damage and wound infection. By using single-cell gel electrophoresis (comet assay), the authors determined the effect of nitrous oxide on DNA damage in circulating leukocytes.
Methods:
In this double-blind, randomized controlled trial, 91 patients undergoing major colorectal surgery were randomized to receive 70% nitrous oxide (n = 31) or nitrous oxide-free anesthesia using 30 (n = 30) or 80% (n = 30) oxygen. Venous blood was collected before and 24 h after surgery. The primary outcome was extent of DNA damage, quantified as the percentage of DNA staining intensity in the comet tail using digital fluorescence microscopy. Incidence of postoperative wound infection was also recorded.
Results:
Nitrous oxide exposure was associated with a two-fold increase in the percentage of DNA intensity in tail (P = 0.0003), but not in the 30 (P = 0.181) or 80% oxygen groups (P = 0.419). There was a positive correlation between the duration of nitrous oxide exposure and extent of DNA damage, r = 0.33, P = 0.029. However, no correlation was observed in nitrous oxide-free patients. The proportions of postoperative wound infection, using the Centers for Disease Control and Prevention criteria, were 19.4% (6 of 31) in the 70% nitrous oxide group and 6.7% (2 of 30) in both the 30 and 80% oxygen groups, P = 0.21. An increase in DNA damage was associated with a higher risk of wound infection, adjusted odds ratio (95% CIs): 1.19 (1.07–1.34), P = 0.003.
Conclusions:
Nitrous oxide increased DNA damage compared with nitrous oxide-free anesthesia and was associated with postoperative wound infection.
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