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Himmelreich N, Blau N, Thöny B. Molecular and metabolic bases of tetrahydrobiopterin (BH 4) deficiencies. Mol Genet Metab 2021; 133:123-136. [PMID: 33903016 DOI: 10.1016/j.ymgme.2021.04.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/09/2021] [Accepted: 04/09/2021] [Indexed: 01/01/2023]
Abstract
Tetrahydrobiopterin (BH4) deficiency is caused by genetic variants in the three genes involved in de novo cofactor biosynthesis, GTP cyclohydrolase I (GTPCH/GCH1), 6-pyruvoyl-tetrahydropterin synthase (PTPS/PTS), sepiapterin reductase (SR/SPR), and the two genes involved in cofactor recycling, carbinolamine-4α-dehydratase (PCD/PCBD1) and dihydropteridine reductase (DHPR/QDPR). Dysfunction in BH4 metabolism leads to reduced cofactor levels and may result in systemic hyperphenylalaninemia and/or neurological sequelae due to secondary deficiency in monoamine neurotransmitters in the central nervous system. More than 1100 patients with BH4 deficiency and 800 different allelic variants distributed throughout the individual genes are tabulated in database of pediatric neurotransmitter disorders PNDdb. Here we provide an update on the molecular-genetic analysis and structural considerations of these variants, including the clinical courses of the genotypes. From a total of 324 alleles, 11 are associated with the autosomal recessive form of GTPCH deficiency presenting with hyperphenylalaninemia (HPA) and neurotransmitter deficiency, 295 GCH1 variant alleles are detected in the dominant form of L-dopa-responsive dystonia (DRD or Segawa disease) while phenotypes of 18 alleles remained undefined. Autosomal recessive variants observed in the PTS (199 variants), PCBD1 (32 variants), and QDPR (141 variants) genes lead to HPA concomitant with central monoamine neurotransmitter deficiency, while SPR deficiency (104 variants) presents without hyperphenylalaninemia. The clinical impact of reported variants is essential for genetic counseling and important for development of precision medicine.
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Affiliation(s)
- Nastassja Himmelreich
- Center for Child and Adolescent Medicine, Dietmar-Hopp Metabolic Center, Division 1, Heidelberg, Germany
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland.
| | - Beat Thöny
- Division of Metabolism and Children's Research Centre, University Children's Hospital Zürich, Zürich, Switzerland.
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2
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Jones P, Lucock M, Scarlett CJ, Veysey M, Beckett EL. Folate and Inflammation – links between folate and features of inflammatory conditions. JOURNAL OF NUTRITION & INTERMEDIARY METABOLISM 2019. [DOI: 10.1016/j.jnim.2019.100104] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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3
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Shi W, Hegeman MA, Doncheva A, van der Stelt I, Bekkenkamp‐Grovenstein M, van Schothorst EM, Brenner C, de Boer VCJ, Keijer J. Transcriptional Response of White Adipose Tissue to Withdrawal of Vitamin B3. Mol Nutr Food Res 2019; 63:e1801100. [PMID: 30990964 PMCID: PMC6618275 DOI: 10.1002/mnfr.201801100] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 03/11/2019] [Indexed: 01/24/2023]
Abstract
SCOPE Distinct markers for mild vitamin B3 deficiency are lacking. To identify these, the molecular responses of white adipose tissue (WAT) to vitamin B3 withdrawal are examined. METHODS AND RESULTS A dietary intervention is performed in male C57BL/6JRccHsd mice, in which a diet without nicotinamide riboside (NR) is compared to a diet with NR at the recommended vitamin B3 level. Both diets contain low but adequate level of tryptophan. Metabolic flexibility and systemic glucose tolerance are analyzed and global transcriptomics, qRT-PCR, and histology of epididymal WAT (eWAT) are performed. A decreased insulin sensitivity and a shift from carbohydrate to fatty acid oxidation in response to vitamin B3 withdrawal are observed. This is consistent with molecular changes in eWAT, including an activated MEK/ERK signaling, a lowering of glucose utilization markers, and an increase in makers of fatty acid catabolism, possibly related to the consistent lower expression of mitochondrial electron transport complexes. The synthesis pathway of tetrahydropteridine (BH4), an essential cofactor for neurotransmitter synthesis, is transcriptionally activated. Genes marking these processes are technically validated. CONCLUSION The downregulation of Anp32a, Tnk2 and the upregulation of Mapk1, Map2k1, Qdpr, Mthfs, and Mthfsl are proposed as a WAT transcriptional signature marker for mild vitamin B3 deficiency.
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Affiliation(s)
- Wenbiao Shi
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands
| | - Maria A. Hegeman
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands,Educational Consultancy & Professional DevelopmentFaculty of Social and Behavioural Sciences, Utrecht University3584CSUtrechtThe Netherlands
| | - Atanaska Doncheva
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands
| | - Inge van der Stelt
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands
| | | | | | - Charles Brenner
- Department of BiochemistryCarver College of Medicine, University of IowaIowa CityIA52242USA
| | - Vincent C. J. de Boer
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands
| | - Jaap Keijer
- Human and Animal PhysiologyWageningen UniversityPO Box 3386700AHWageningenThe Netherlands
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Garbazza C, Manconi M. Management Strategies for Restless Legs Syndrome/Willis-Ekbom Disease During Pregnancy. Sleep Med Clin 2018; 13:335-348. [PMID: 30098751 DOI: 10.1016/j.jsmc.2018.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Restless legs syndrome/Willis-Ekbom disease is a common disorder during pregnancy that may significantly impact on the health of affected women, leading to negative consequences in the short and long term. An accurate diagnosis helps to recognize the syndrome and choose the optimal therapeutic strategy, based on the characteristics and needs of the patient. This article summarizes the main treatment options recommended by the consensus clinical guidelines of the International Restless Legs Syndrome Study Group and provides a short guide to the management of restless leg syndrome during pregnancy in clinical practice.
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Affiliation(s)
- Corrado Garbazza
- Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital of Lugano (EOC), Via Tesserete 46, Lugano CH-6903, Switzerland.
| | - Mauro Manconi
- Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital of Lugano (EOC), Via Tesserete 46, Lugano CH-6903, Switzerland
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5
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Affiliation(s)
- Teodoro Bottiglieri
- Kimberly H. Courtwright and Joseph W. Summers Metabolic Disease Center, Baylor Research Institute
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Stanhewicz AE, Kenney WL. Role of folic acid in nitric oxide bioavailability and vascular endothelial function. Nutr Rev 2017; 75:61-70. [PMID: 27974600 PMCID: PMC5155615 DOI: 10.1093/nutrit/nuw053] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Folic acid is a member of the B-vitamin family and is essential for amino acid metabolism. Adequate intake of folic acid is vital for metabolism, cellular homeostasis, and DNA synthesis. Since the initial discovery of folic acid in the 1940s, folate deficiency has been implicated in numerous disease states, primarily those associated with neural tube defects in utero and neurological degeneration later in life. However, in the past decade, epidemiological studies have identified an inverse relation between both folic acid intake and blood folate concentration and cardiovascular health. This association inspired a number of clinical studies that suggested that folic acid supplementation could reverse endothelial dysfunction in patients with cardiovascular disease (CVD). Recently, in vitro and in vivo studies have begun to elucidate the mechanism(s) through which folic acid improves vascular endothelial function. These studies, which are the focus of this review, suggest that folic acid and its active metabolite 5-methyl tetrahydrofolate improve nitric oxide (NO) bioavailability by increasing endothelial NO synthase coupling and NO production as well as by directly scavenging superoxide radicals. By improving NO bioavailability, folic acid may protect or improve endothelial function, thereby preventing or reversing the progression of CVD in those with overt disease or elevated CVD risk.
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Affiliation(s)
- Anna E Stanhewicz
- A.E. Stanhewicz and W.L. Kenney are with the Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, USA.
| | - W Larry Kenney
- A.E. Stanhewicz and W.L. Kenney are with the Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, USA
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7
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Zahra C, Tabone C, Camilleri G, Felice AE, Farrugia R, Bezzina Wettinger S. Genetic causes of Parkinson's disease in the Maltese: a study of selected mutations in LRRK2, MTHFR, QDPR and SPR. BMC MEDICAL GENETICS 2016; 17:65. [PMID: 27613114 PMCID: PMC5016953 DOI: 10.1186/s12881-016-0327-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 08/27/2016] [Indexed: 12/05/2022]
Abstract
Background Mutations in Leucine-rich repeat kinase 2 NM_198578 (LRRK2 c.6055G > A (p.G2019S), LRRK2 c.4321C > G (p.R1441G)) and alpha-synuclein NM_000345 (SNCA c.209G > A (p.A53T)) genes causing Parkinson’s disease (PD) are common in Mediterranean populations. Variants in the Quinoid Dihydropteridine Reductase NM_000320 (QDPR c.68G > A (p.G23D)), Sepiapterin Reductase NM_003124 (SPR c.596-2A > G) and Methylenetetrahydrofolate Reductase NM_005957 (MTHFR c.677C > T and c.1298A > C) genes are frequent in Malta and potential candidates for PD. Methods 178 cases and 402 control samples from Malta collected as part of the Geoparkinson project were genotyped for MTHFR polymorphisms, QDPR and SPR mutations. Only PD and parkinsonism cases were tested for SNCA and LRRK2 mutations. Results LRRK2 c.4321C > G and SNCA c.209G > A were not detected. The LRRK2 c.6055G > A mutation was found in 3.1 % of Maltese PD cases. The QDPR mutation was found in both cases and controls and did not increase risk for PD. The SPR mutation was found in controls only. The odds ratios for MTHFR polymorphisms were not elevated. Conclusions The LRRK2 c.6055G > A is a cause of PD in the Maltese, whilst QDPR c.68G > A, SPR c.596-2A > G and MTHFR c.677C > T and c.1298A > C are not important determinants of PD. Electronic supplementary material The online version of this article (doi:10.1186/s12881-016-0327-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Charmaine Zahra
- Laboratory of Molecular Genetics, Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Christine Tabone
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta
| | - Graziella Camilleri
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta
| | - Alex E Felice
- Laboratory of Molecular Genetics, Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Rosienne Farrugia
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta
| | - Stephanie Bezzina Wettinger
- Laboratory of Molecular Genetics, Department of Physiology and Biochemistry, University of Malta, Msida, Malta. .,Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta.
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Singh MD, Thomas P, Owens J, Hague W, Fenech M. Potential role of folate in pre-eclampsia. Nutr Rev 2015; 73:694-722. [PMID: 26359215 DOI: 10.1093/nutrit/nuv028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Dietary deficiencies of folate and other B vitamin cofactors involved in one-carbon metabolism, together with genetic polymorphisms in key folate-methionine metabolic pathway enzymes, are associated with increases in circulating plasma homocysteine, reduction in DNA methylation patterns, and genome instability events. All of these biomarkers have also been associated with pre-eclampsia. The aim of this review was to explore the literature and identify potential knowledge gaps in relation to the role of folate at the genomic level in either the etiology or the prevention of pre-eclampsia. A systematic search strategy was designed to identify citations in electronic databases for the following terms: folic acid supplementation AND pre-eclampsia, folic acid supplementation AND genome stability, folate AND genome stability AND pre-eclampsia, folic acid supplementation AND DNA methylation, and folate AND DNA methylation AND pre-eclampsia. Forty-three articles were selected according to predefined selection criteria. The studies included in the present review were not homogeneous, which made pooled analysis of the data very difficult. The present review highlights associations between folate deficiency and certain biomarkers observed in various tissues of women at risk of pre-eclampsia. Further investigation is required to understand the role of folate in either the etiology or the prevention of pre-eclampsia.
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Affiliation(s)
- Mansi Dass Singh
- M.D. Singh, J. Owens, and W. Hague are with the School of Pediatrics and Reproductive Health, Discipline of Obstetrics and Gynecology, Faculty of Health Sciences, Robinson Institute, Australian Research Centre for Health of Women and Babies, The University of Adelaide, Adelaide, South Australia, Australia. M.D. Singh, P. Thomas and M. Fenech are with the Genome Health and Personalized Nutrition Laboratory Commonwealth Scientific and Industrial Research Organization (CSIRO), Food and Nutrition Flagship, Adelaide, South Australia, Australia
| | - Philip Thomas
- M.D. Singh, J. Owens, and W. Hague are with the School of Pediatrics and Reproductive Health, Discipline of Obstetrics and Gynecology, Faculty of Health Sciences, Robinson Institute, Australian Research Centre for Health of Women and Babies, The University of Adelaide, Adelaide, South Australia, Australia. M.D. Singh, P. Thomas and M. Fenech are with the Genome Health and Personalized Nutrition Laboratory Commonwealth Scientific and Industrial Research Organization (CSIRO), Food and Nutrition Flagship, Adelaide, South Australia, Australia
| | - Julie Owens
- M.D. Singh, J. Owens, and W. Hague are with the School of Pediatrics and Reproductive Health, Discipline of Obstetrics and Gynecology, Faculty of Health Sciences, Robinson Institute, Australian Research Centre for Health of Women and Babies, The University of Adelaide, Adelaide, South Australia, Australia. M.D. Singh, P. Thomas and M. Fenech are with the Genome Health and Personalized Nutrition Laboratory Commonwealth Scientific and Industrial Research Organization (CSIRO), Food and Nutrition Flagship, Adelaide, South Australia, Australia
| | - William Hague
- M.D. Singh, J. Owens, and W. Hague are with the School of Pediatrics and Reproductive Health, Discipline of Obstetrics and Gynecology, Faculty of Health Sciences, Robinson Institute, Australian Research Centre for Health of Women and Babies, The University of Adelaide, Adelaide, South Australia, Australia. M.D. Singh, P. Thomas and M. Fenech are with the Genome Health and Personalized Nutrition Laboratory Commonwealth Scientific and Industrial Research Organization (CSIRO), Food and Nutrition Flagship, Adelaide, South Australia, Australia
| | - Michael Fenech
- M.D. Singh, J. Owens, and W. Hague are with the School of Pediatrics and Reproductive Health, Discipline of Obstetrics and Gynecology, Faculty of Health Sciences, Robinson Institute, Australian Research Centre for Health of Women and Babies, The University of Adelaide, Adelaide, South Australia, Australia. M.D. Singh, P. Thomas and M. Fenech are with the Genome Health and Personalized Nutrition Laboratory Commonwealth Scientific and Industrial Research Organization (CSIRO), Food and Nutrition Flagship, Adelaide, South Australia, Australia.
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9
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A NOS3 polymorphism determines endothelial response to folate in children with type 1 diabetes or obesity. J Pediatr 2015; 166:319-25.e1. [PMID: 25477161 DOI: 10.1016/j.jpeds.2014.10.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/05/2014] [Accepted: 10/21/2014] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To determine the effect of polymorphisms in NOS3 and folate pathway enzymes on vascular function and folate status and endothelial response to folate in children with diabetes or obesity. STUDY DESIGN A total of 244 subjects (age 13.8 ± 2.8 years, 125 males) were studied for NOS3 and/or folate pathway polymorphisms using polymerase chain reaction/restriction fragment length polymorphism, including at baseline: 139 with type 1 diabetes; 58 with obesity; and 47 controls. The effect of NOS3 genotype on endothelial response to folate (5 mg) was assessed in 85 subjects with diabetes and 28 obese subjects who received active treatment during intervention trials. Vascular function (flow-mediated dilatation [FMD] and glyceryl trinitrate-mediated dilatation), clinical, and biochemical measurements were assessed at baseline and 8 weeks in folate intervention studies. RESULTS Folate pathway enzyme and NOS3 polymorphisms did not significantly affect baseline vascular function. The polymorphism in intron 4 of endothelial nitric oxide synthase altered endothelial response to folate significantly: in subjects with diabetes FMD improved by 6.4 ± 5% (insertion carriers) vs 2.3 ± 6.6% (deletion carriers), P = .01; in obese subjects FMD improved by 1.8 ± 5.4% (insertion carriers) and deteriorated by -3.2 ± 7.2% (deletion carriers), P = .05. More subjects carrying the insertion normalized FMD after folate supplementation (insertion 64% vs deletion 28%, χ(2) = 10.14, P = .001). CONCLUSIONS A NOS3 polymorphism predicts endothelial response to folate in children with diabetes or obesity, with implications for vascular risk and folate intervention studies.
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10
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Bendall JK, Douglas G, McNeill E, Channon KM, Crabtree MJ. Tetrahydrobiopterin in cardiovascular health and disease. Antioxid Redox Signal 2014; 20:3040-77. [PMID: 24294830 PMCID: PMC4038990 DOI: 10.1089/ars.2013.5566] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 11/01/2013] [Accepted: 12/02/2013] [Indexed: 01/03/2023]
Abstract
Tetrahydrobiopterin (BH4) functions as a cofactor for several important enzyme systems, and considerable evidence implicates BH4 as a key regulator of endothelial nitric oxide synthase (eNOS) in the setting of cardiovascular health and disease. BH4 bioavailability is determined by a balance of enzymatic de novo synthesis and recycling, versus degradation in the setting of oxidative stress. Augmenting vascular BH4 levels by pharmacological supplementation has been shown in experimental studies to enhance NO bioavailability. However, it has become more apparent that the role of BH4 in other enzymatic pathways, including other NOS isoforms and the aromatic amino acid hydroxylases, may have a bearing on important aspects of vascular homeostasis, inflammation, and cardiac function. This article reviews the role of BH4 in cardiovascular development and homeostasis, as well as in pathophysiological processes such as endothelial and vascular dysfunction, atherosclerosis, inflammation, and cardiac hypertrophy. We discuss the therapeutic potential of BH4 in cardiovascular disease states and attempt to address how this modulator of intracellular NO-redox balance may ultimately provide a powerful new treatment for many cardiovascular diseases.
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Affiliation(s)
- Jennifer K Bendall
- Division of Cardiovascular Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford , John Radcliffe Hospital, Oxford, United Kingdom
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11
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Srivanitchapoom P, Pandey S, Hallett M. Restless legs syndrome and pregnancy: a review. Parkinsonism Relat Disord 2014; 20:716-22. [PMID: 24768121 DOI: 10.1016/j.parkreldis.2014.03.027] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 11/17/2022]
Abstract
Restless legs syndrome (RLS) is a common sensorimotor neurological disorder that is diagnosed according to the revised criteria of the International RLS Study Group (IRLSSG). The pathophysiology of RLS is still unknown and its prevalence is influenced by ethnicity, age, and gender. RLS is divided into two types by etiology: primary or idiopathic and secondary. Primary RLS is strongly influenced by a genetic component while secondary RLS is caused by other associated conditions such as end-stage renal disease or peripheral neuropathy. Another common condition associated with RLS is pregnancy. The prevalence of RLS during pregnancy is two to three times higher than in the normal population and is influenced by the trimester and the number of parity. The main mechanisms that may contribute to the pathophysiology of RLS during pregnancy are hormonal changes and iron and folate status. Standard medications for treating RLS during pregnancy are not established. Most medications have been used according to the evidence from non-pregnant patients. Therefore, consideration of the medical treatment for treating RLS during pregnancy should be balanced between the benefit of relieving the symptoms and maternal and fetal risk. In general, the prognosis of RLS during pregnancy is good and symptoms are usually relieved after delivery.
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Affiliation(s)
- Prachaya Srivanitchapoom
- Division of Neurology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, 10700, Thailand; Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sanjay Pandey
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Govind Ballabh Pant Hospital, New Delhi 110002, India
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Chi Y, Pei L, Chen G, Song X, Zhao A, Chen T, Su M, Zhang Y, Liu J, Ren A, Zheng X, Xie G, Jia W. Metabonomic Profiling of Human Placentas Reveals Different Metabolic Patterns among Subtypes of Neural Tube Defects. J Proteome Res 2014; 13:934-45. [PMID: 24397701 DOI: 10.1021/pr4009805] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Yi Chi
- School
of Pharmacy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lijun Pei
- Institute
of Population Research, Peking University, 5 Yiheyuan Road, Beijing 100871, China
| | - Gong Chen
- Institute
of Population Research, Peking University, 5 Yiheyuan Road, Beijing 100871, China
- WHO
Collaborating Center for Reproductive Health and Population Science, 5 Yiheyuan Road, Beijing 100871, China
| | - Xinming Song
- Institute
of Population Research, Peking University, 5 Yiheyuan Road, Beijing 100871, China
- WHO
Collaborating Center for Reproductive Health and Population Science, 5 Yiheyuan Road, Beijing 100871, China
| | - Aihua Zhao
- Center
for Translational Medicine, Shanghai Jiao Tong University Affiliated
Sixth People’s Hospital, 600
Yishan Road, Shanghai 200233, China
| | - Tianlu Chen
- Center
for Translational Medicine, Shanghai Jiao Tong University Affiliated
Sixth People’s Hospital, 600
Yishan Road, Shanghai 200233, China
| | - Mingming Su
- University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, Hawaii 96813, United States
| | - Yinan Zhang
- Center
for Translational Medicine, Shanghai Jiao Tong University Affiliated
Sixth People’s Hospital, 600
Yishan Road, Shanghai 200233, China
| | - Jianmeng Liu
- Health Science
Center, Peking University, 38 Xueyuan Road, Beijing 100871, China
| | - Aiguo Ren
- Health Science
Center, Peking University, 38 Xueyuan Road, Beijing 100871, China
| | - Xiaoying Zheng
- Institute
of Population Research, Peking University, 5 Yiheyuan Road, Beijing 100871, China
- WHO
Collaborating Center for Reproductive Health and Population Science, 5 Yiheyuan Road, Beijing 100871, China
| | - Guoxiang Xie
- Center
for Translational Medicine, Shanghai Jiao Tong University Affiliated
Sixth People’s Hospital, 600
Yishan Road, Shanghai 200233, China
- University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, Hawaii 96813, United States
| | - Wei Jia
- Center
for Translational Medicine, Shanghai Jiao Tong University Affiliated
Sixth People’s Hospital, 600
Yishan Road, Shanghai 200233, China
- University of Hawaii Cancer Center, 701 Ilalo Street, Honolulu, Hawaii 96813, United States
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Kirsch SH, Herrmann W, Obeid R. Genetic defects in folate and cobalamin pathways affecting the brain. Clin Chem Lab Med 2013. [DOI: 10.1515/cclm-2012-0673] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Zheng X, Su M, Pei L, Zhang T, Ma X, Qiu Y, Xia H, Wang F, Zheng X, Gu X, Song X, Li X, Qi X, Chen G, Bao Y, Chen T, Chi Y, Zhao A, Jia W. Metabolic Signature of Pregnant Women with Neural Tube Defects in Offspring. J Proteome Res 2011; 10:4845-54. [DOI: 10.1021/pr200666d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Xiaoying Zheng
- WHO Collaborating Center for Reproductive Health and Population Science, Beijing, P. R. China
- Institute of Population, Peking University, Beijing, P. R. China
| | - Mingming Su
- Ministry of Education Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, P. R. China
- David H Murdock Research Institute, North Carolina Research Campus, Kannapolis, North Carolina, United States
| | - Lijun Pei
- Institute of Population, Peking University, Beijing, P. R. China
| | - Ting Zhang
- Capital Institute of Pediatrics, Beijing, P. R. China
| | - Xu Ma
- Reproductive and Genetic Center of National Research Institute for Family Planning, Beijing, P. R. China
| | - Yunping Qiu
- Department of Nutrition, University of North Carolina at Greensboro/The UNCG Center for Research Excellence in Bioactive Food Components, North Carolina Research Campus, Kannapolis, North Carolina, United States
| | - Hongfei Xia
- Reproductive and Genetic Center of National Research Institute for Family Planning, Beijing, P. R. China
| | - Fang Wang
- Capital Institute of Pediatrics, Beijing, P. R. China
| | - Xiaojiao Zheng
- Department of Nutrition, University of North Carolina at Greensboro/The UNCG Center for Research Excellence in Bioactive Food Components, North Carolina Research Campus, Kannapolis, North Carolina, United States
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Xue Gu
- Capital Institute of Pediatrics, Beijing, P. R. China
| | - Xinming Song
- WHO Collaborating Center for Reproductive Health and Population Science, Beijing, P. R. China
- Institute of Population, Peking University, Beijing, P. R. China
| | - Xin Li
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Xin Qi
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Gong Chen
- WHO Collaborating Center for Reproductive Health and Population Science, Beijing, P. R. China
- Institute of Population, Peking University, Beijing, P. R. China
| | - Yihua Bao
- Capital Institute of Pediatrics, Beijing, P. R. China
| | - Tianlu Chen
- Ministry of Education Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Yi Chi
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Aihua Zhao
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Wei Jia
- Institute of Population, Peking University, Beijing, P. R. China
- Department of Nutrition, University of North Carolina at Greensboro/The UNCG Center for Research Excellence in Bioactive Food Components, North Carolina Research Campus, Kannapolis, North Carolina, United States
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Crabtree MJ, Channon KM. Synthesis and recycling of tetrahydrobiopterin in endothelial function and vascular disease. Nitric Oxide 2011; 25:81-8. [PMID: 21550412 PMCID: PMC5357050 DOI: 10.1016/j.niox.2011.04.004] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 04/14/2011] [Accepted: 04/17/2011] [Indexed: 01/08/2023]
Abstract
Nitric oxide, generated by the nitric oxide synthase (NOS) enzymes, plays pivotal roles in cardiovascular homeostasis and in the pathogenesis of cardiovascular disease. The NOS cofactor, tetrahydrobiopterin (BH4), is an important regulator of NOS function, since BH4 is required to maintain enzymatic coupling of L-arginine oxidation, to produce NO. Loss or oxidation of BH4 to 7,8-dihydrobiopterin (BH2) is associated with NOS uncoupling, resulting in the production of superoxide rather than NO. In addition to key roles in folate metabolism, dihydrofolate reductase (DHFR) can 'recycle' BH2, and thus regenerate BH4. It is therefore likely that net BH4 cellular bioavailability reflects the balance between de novo BH4 synthesis, loss of BH4 by oxidation to BH2, and the regeneration of BH4 by DHFR. Recent studies have implicated BH4 recycling in the direct regulation of eNOS uncoupling, showing that inhibition of BH4 recycling using DHFR-specific siRNA and methotrexate treatment leads to eNOS uncoupling in endothelial cells and the hph-1 mouse model of BH4 deficiency, even in the absence of oxidative stress. These studies indicate that not only BH4 level, but the recycling pathways regulating BH4 bioavailability represent potential therapeutic targets and will be discussed in this review.
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Affiliation(s)
- Mark J Crabtree
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
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16
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Rakovich T, Boland C, Bernstein I, Chikwana VM, Iwata-Reuyl D, Kelly VP. Queuosine deficiency in eukaryotes compromises tyrosine production through increased tetrahydrobiopterin oxidation. J Biol Chem 2011; 286:19354-63. [PMID: 21487017 DOI: 10.1074/jbc.m111.219576] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Queuosine is a modified pyrrolopyrimidine nucleoside found in the anticodon loop of transfer RNA acceptors for the amino acids tyrosine, asparagine, aspartic acid, and histidine. Because it is exclusively synthesized by bacteria, higher eukaryotes must salvage queuosine or its nucleobase queuine from food and the gut microflora. Previously, animals made deficient in queuine died within 18 days of withdrawing tyrosine, a nonessential amino acid, from the diet (Marks, T., and Farkas, W. R. (1997) Biochem. Biophys. Res. Commun. 230, 233-237). Here, we show that human HepG2 cells deficient in queuine and mice made deficient in queuosine-modified transfer RNA, by disruption of the tRNA guanine transglycosylase enzyme, are compromised in their ability to produce tyrosine from phenylalanine. This has similarities to the disease phenylketonuria, which arises from mutation in the enzyme phenylalanine hydroxylase or from a decrease in the supply of its cofactor tetrahydrobiopterin (BH4). Immunoblot and kinetic analysis of liver from tRNA guanine transglycosylase-deficient animals indicates normal expression and activity of phenylalanine hydroxylase. By contrast, BH4 levels are significantly decreased in the plasma, and both plasma and urine show a clear elevation in dihydrobiopterin, an oxidation product of BH4, despite normal activity of the salvage enzyme dihydrofolate reductase. Our data suggest that queuosine modification limits BH4 oxidation in vivo and thereby potentially impacts on numerous physiological processes in eukaryotes.
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Affiliation(s)
- Tatsiana Rakovich
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
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17
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Cario H, Smith DE, Blom H, Blau N, Bode H, Holzmann K, Pannicke U, Hopfner KP, Rump EM, Ayric Z, Kohne E, Debatin KM, Smulders Y, Schwarz K. Dihydrofolate reductase deficiency due to a homozygous DHFR mutation causes megaloblastic anemia and cerebral folate deficiency leading to severe neurologic disease. Am J Hum Genet 2011; 88:226-31. [PMID: 21310277 DOI: 10.1016/j.ajhg.2011.01.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Revised: 01/13/2011] [Accepted: 01/17/2011] [Indexed: 11/27/2022] Open
Abstract
The importance of intracellular folate metabolism is illustrated by the severity of symptoms and complications caused by inborn disorders of folate metabolism or by folate deficiency. We examined three children of healthy, distantly related parents presenting with megaloblastic anemia and cerebral folate deficiency causing neurologic disease with atypical childhood absence epilepsy. Genome-wide homozygosity mapping revealed a candidate region on chromosome 5 including the dihydrofolate reductase (DHFR) locus. DHFR sequencing revealed a homozygous DHFR mutation, c.458A>T (p.Asp153Val), in all siblings. The patients' folate profile in red blood cells (RBC), plasma, and cerebrospinal fluid (CSF), analyzed by liquid chromatography tandem mass spectrometry, was compatible with DHFR deficiency. DHFR activity and fluorescein-labeled methotrexate (FMTX) binding were severely reduced in EBV-immortalized lymphoblastoid cells of all patients. Heterozygous cells displayed intermediate DHFR activity and FMTX binding. RT-PCR of DHFR mRNA revealed no differences between wild-type and DHFR mutation-carrying cells, whereas protein expression was reduced in cells with the DHFR mutation. Treatment with folinic acid resulted in the resolution of hematological abnormalities, normalization of CSF folate levels, and improvement of neurological symptoms. In conclusion, the homozygous DHFR mutation p.Asp153Val causes DHFR deficiency and leads to a complex hematological and neurological disease that can be successfully treated with folinic acid. DHFR is necessary for maintaining sufficient CSF and RBC folate levels, even in the presence of adequate nutritional folate supply and normal plasma folate.
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18
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Hyland K, Shoffner J, Heales SJ. Cerebral folate deficiency. J Inherit Metab Dis 2010; 33:563-70. [PMID: 20668945 DOI: 10.1007/s10545-010-9159-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 05/21/2010] [Accepted: 06/21/2010] [Indexed: 11/26/2022]
Abstract
Cerebral folate deficiency (CFD) is defined as any neurological syndrome associated with a low cerebrospinal fluid (CSF) concentration of 5-methyltetrahydrofolate (5MTHF) in the presence of normal peripheral folate status. CFD has a wide clinical presentation, with reported signs and symptoms generally beginning at around 4 months of age with irritability and sleep disturbances. These can be followed by psychomotor retardation, dyskinesia, cerebellar ataxia and spastic diplegia. Other signs may include deceleration of head growth, visual disturbances and sensorineural hearing loss. Identification of CFD is achieved by determining 5MTHF concentration in CSF. Once identified, CFD can in many cases be treated by administering oral folinic acid. Supplementation with folic acid is contraindicated and, if used, may exacerbate the CSF 5MTHF deficiency. Generation of autoantibodies against the folate receptor required to transport 5MTHF into CSF and mutations in the folate receptor 1 (FOLR1) gene have been reported to be causes of CFD. However, other mechanisms are probably also involved, as CFD has been reported in Aicardi-Goutiere's and Rett syndromes and in mitochondriopathies. Several metabolic conditions and a number of widely used drugs can also lead to a decrease in the concentration of CSF 5MTHF, and these should be considered in the differential diagnosis if a low concentration of 5MTHF is found following CSF analysis.
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19
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Tsai EJ, Kass DA. Cyclic GMP signaling in cardiovascular pathophysiology and therapeutics. Pharmacol Ther 2009; 122:216-38. [PMID: 19306895 PMCID: PMC2709600 DOI: 10.1016/j.pharmthera.2009.02.009] [Citation(s) in RCA: 298] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 02/07/2023]
Abstract
Cyclic guanosine 3',5'-monophosphate (cGMP) mediates a wide spectrum of physiologic processes in multiple cell types within the cardiovascular system. Dysfunctional signaling at any step of the cascade - cGMP synthesis, effector activation, or catabolism - have been implicated in numerous cardiovascular diseases, ranging from hypertension to atherosclerosis to cardiac hypertrophy and heart failure. In this review, we outline each step of the cGMP signaling cascade and discuss its regulation and physiologic effects within the cardiovascular system. In addition, we illustrate how cGMP signaling becomes dysregulated in specific cardiovascular disease states. The ubiquitous role cGMP plays in cardiac physiology and pathophysiology presents great opportunities for pharmacologic modulation of the cGMP signal in the treatment of cardiovascular diseases. We detail the various therapeutic interventional strategies that have been developed or are in development, summarizing relevant preclinical and clinical studies.
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Affiliation(s)
- Emily J Tsai
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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20
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Verbeek MM, Blom AM, Wevers RA, Lagerwerf AJ, van de Geer J, Willemsen MAAP. Technical and biochemical factors affecting cerebrospinal fluid 5-MTHF, biopterin and neopterin concentrations. Mol Genet Metab 2008; 95:127-32. [PMID: 18722797 DOI: 10.1016/j.ymgme.2008.07.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 07/08/2008] [Accepted: 07/08/2008] [Indexed: 11/17/2022]
Abstract
BACKGROUND The diagnosis of pediatric neurologic disorders with a deficiency in the biosynthesis of either the neurotransmitters serotonin and dopamine, or the co-factor tetrahydrobiopterin or a cerebral 5-methyltetrahydrofolate (5-MTHF) deficiency, strongly relies on a robust analysis of neurotransmitter metabolites, pterins and 5-MTHF in the cerebrospinal fluid (CSF). The aim of this study was to investigate which technical and biochemical factors affect the CSF concentration of 5-MTHF, neopterin and biopterin in a pediatric population. METHODS We studied effects of the ventriculo-spinal gradient, total protein concentration, pretreatment with ascorbic acid (in case of 5-MTHF analysis), pretreatment of CSF with trichloro acetic acid (TCA)/dithiotreitol (DTE) and oxidation with either iodine or manganese oxide (in case of pterin analysis), storage time and age of the patients. We included CSF samples from children until the age of 18 years and analysed 5-MTHF, neopterin, biopterin, homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA) and total protein. RESULTS The major findings of our study are: (1) CSF 5-MTHF, neopterin and biopterin concentrations are not affected by the ventriculo-spinal gradient; (2) pretreatment of CSF with ascorbic acid has negligible effects on 5-MTHF concentrations; (3) pretreatment of CSF with TCA/DTE and oxidation with iodine results in the most accurate determination of neopterin and biopterin; (4) when adjusted for age and total protein, CSF 5-MTHF correlated with 5-HIAA, but not with HVA; (5) the reference value of 5-MTHF in CSF in childhood is age-dependent (r=-0.634; p0.001); (6) we did not observe an age-dependency for neopterin and biopterin in CSF. CONCLUSION 5-MTHF, neopterin and biopterin can be analysed in any volume of CSF that is collected. For correct analysis of pterins, CSF will have to be pretreated to stabilize the concentrations and stored properly, whereas such pretreatment is not necessary for 5-MTHF.
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Affiliation(s)
- M M Verbeek
- Department of Laboratory of Pediatrics, Radboud University Nijmegen Medical Centre, Donders Centre for Neuroscience, The Netherlands.
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21
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Moens AL, Vrints CJ, Claeys MJ, Timmermans JP, Champion HC, Kass DA. Mechanisms and potential therapeutic targets for folic acid in cardiovascular disease. Am J Physiol Heart Circ Physiol 2008; 294:H1971-7. [PMID: 18375715 DOI: 10.1152/ajpheart.91503.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Folic acid (FA) is a member of the B-vitamin family with cardiovascular roles in homocysteine regulation and endothelial nitric oxide synthase (eNOS) activity. Its interaction with eNOS is thought to be due to the enhancement of tetrahydrobiopterin bioavailability, helping maintain eNOS in its coupled state to favor the generation of nitric oxide rather than oxygen free radicals. FA also plays a role in the prevention of several cardiac and noncardiac malformations, has potent direct antioxidant and antithrombotic effects, and can interfere with the production of the endothelial-derived hyperpolarizing factor. These multiple mechanisms of action have led to studies regarding the therapeutic potential of FA in cardiovascular disease. To date, studies have demonstrated that FA ameliorates endothelial dysfunction and nitrate tolerance and can improve pathological features of atherosclerosis. These effects appear to be homocysteine independent but rather related to their role in eNOS function. Given the growing evidence that nitric oxide synthase uncoupling plays a major role in many cardiovascular disorders, the potential of exogenous FA as an inexpensive and safe oral therapy is intriguing and is stimulating ongoing investigations.
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Affiliation(s)
- An L Moens
- Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
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22
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Abstract
There is an association between cognitive function and vitamin B12 and folate status. Both vitamins participate in recycling the potentially toxic amino acid homocysteine to methionine and, ultimately, to the methyl donor S-adenosylmethionine (SAM). Consequently, B12 and folate indirectly influence glutathione synthesis – a major intracellular antioxidant. Neuroinflammation and oxidative stress are early features of Alzheimer’s disease (AD). Such stress impairs homocysteine recycling, degrades folate and decreases its cellular retention, resulting in limited SAM availability and increased homocysteine levels. Oxidized homocysteine derivatives, such as homocysteic acid, can initiate a vicious cycle by promoting free-radical formation. Decreased SAM also fosters development of characteristic AD neuropathologies – neurofibrillary tangles and amyloid plaques. The latter generate additional free radicals in a further feed-forward cascade. Future therapies should simultaneously halt neuroinflammation, restore redox homeostasis and replace depleted intracellular B vitamins. Developing early markers for these harmful processes will allow targeting of such therapy before irreversible cellular damage ensues.
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Affiliation(s)
- Andrew McCaddon
- Cardiff University, Cardiff School of Medicine, Gardden Road Surgery, Rhosllanerchrugog, Wrexham, North Wales, LL14 2EN, UK
| | - Peter R Hudson
- Maelor Hospital, Department of Medical Biochemistry, Croesnewydd Road, Wrexham, North Wales, LL13 7TD, UK
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23
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Abstract
Tetrahydrobiopterin is the reduced unconjugated pterin that serves as an essential cofactor for the normal enzymatic function of the aromatic amino acid hydroxylases and for the nitric oxide synthases (NOS). Its role in the latter biochemistry is being increasing appreciated, as depletion or oxidation of BH4 results in a condition of NOS uncoupling, resulting in a nitroso-oxidative imbalance. Recent experimental studies support an important pathophysiologic role of BH4 deficiency as well as the therapeutic potential of BH4 repletion for hypertension, endothelial dysfunction, atherosclerosis, diabetes, cardiac hypertrophic remodeling, and heart failure. In addition to BH4, studies are also examining the potential role of folic acid therapy, because folic acid can enhance BH4 levels and the NOS coupling state. This review summarizes these recent studies focusing on the biochemistry and pharmacology of BH4 and its potential role for treating cardiovascular disease.
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Affiliation(s)
- An L Moens
- Department of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
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24
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Hyland K. Inherited disorders affecting dopamine and serotonin: critical neurotransmitters derived from aromatic amino acids. J Nutr 2007; 137:1568S-1572S; discussion 1573S-1575S. [PMID: 17513427 DOI: 10.1093/jn/137.6.1568s] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many inherited disorders affecting aromatic amino acid metabolism have been described. This review will concentrate on the defects that lead to deficiencies of dopamine and serotonin within the central nervous system. Phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase all require tetrahydrobiopterin (BH4) as a cofactor. Inherited defects that reduce the concentration of BH4, therefore, in general, lead to phenylketonuria and to deficiencies of dopamine and serotonin, as tyrosine hydroxylase and tryptophan hydroxylase are the rate-limiting enzymes required for the synthesis of these neurotransmitters. Primary inherited defects of tyrosine hydroxylase and aromatic l-amino acid decarboxylase have also been described. The clinical phenotypes are very similar to those observed in patients with defects of BH4 metabolism. Differential diagnosis is critical as treatment is different in each of the disorders. To date, a primary deficiency of tryptophan hydroxylase has not been described; when it finally is, the clinical phenotype might surprise us, as many groups around the world have been searching for such a defect for a long time.
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Affiliation(s)
- Keith Hyland
- Department of Neurochemistry, Horizon Molecular Medicine, Atlanta, Georgia 30338, USA.
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25
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Wilson JB, Welsch M, Allen J, Thomson J, Tulley R, Lefevre M. The association of homocysteine and related factors to brachial artery diameter and flow-mediated dilation. Metabolism 2007; 56:641-8. [PMID: 17445539 DOI: 10.1016/j.metabol.2006.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 12/18/2006] [Indexed: 11/22/2022]
Abstract
Brachial artery flow-mediated dilation (BAFMD) has been proposed as a measurement of the degree and severity of cardiovascular disease. The purpose of this study was to (1) evaluate the associations between BAFMD and homocysteine, folate, vitamin B(12), vitamin B(6); (2) examine the influence of 5,10-methylenetetrahydrofolate reductase (MTHFR) genotypes on homocysteine levels and BAFMD; and (3) evaluate the effect of homocysteine on the baseline diameter of the vessel vs BAFMD. A total of 174 healthy research subjects were examined for BAFMD, homocysteine, folate, vitamin B(12), vitamin B(6), and MTHFR genotype, nucleotide 677 C-->T. The data indicated a significant inverse correlation between homocysteine and BAFMD (r = -0.1763, P = .02). There was a significant difference in BAFMD between MTHFR genotype groups (P = .01) (T/T vs C/C, P = .042; C/C vs C/T, P = .13; T/T vs C/T, P = .003). Homocysteine was significantly associated with the baseline brachial artery diameter (r = 0.1878, P = .013). The data confirmed a significant inverse correlation between baseline diameter and BAFMD (r = -0.3321, P = .0001). Regression analysis indicated that the MTHFR genotype, homocysteine, and age were significant predictors of BAFMD (P = .0001, r(2) = 0.118). When the baseline brachial diameter was incorporated into the model, the effect of homocysteine on BAFMD disappeared. The present data indicate an association between homocysteine and BAFMD and reduced BAFMD in individuals with the MTHFR nucleotide 677 T/T genotype, despite similar blood values for folate and homocysteine. Finally, the data suggest that the effect of homocysteine on vascular reactivity is in part a consequence of its influence on baseline brachial artery diameter.
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Affiliation(s)
- Joanie B Wilson
- Department of Kinesiology, Louisiana State University, Baton Rouge, LA 70802, USA
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26
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Oster rediscovered--mega-dose folate for symptomatic atherosclerosis. Med Hypotheses 2007; 69:325-32. [PMID: 17224245 DOI: 10.1016/j.mehy.2004.11.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 11/13/2004] [Indexed: 10/23/2022]
Abstract
Thirty years ago, Kurt Oster promulgated the avant-garde theory that bovine xanthine oxidase, absorbed intact from homogenized milk, promoted atherogenesis by oxidatively damaging membrane plasmalogens. Under the mistaken impression that folic acid is a xanthine oxidase inhibitor, he administered high-dose folate (80 mg daily) to hundreds of patients afflicted with symptomatic atherosclerosis, and reported marked improvements in angina, intermittent claudication, and wound healing; he also suspected that this regimen was decreasing heart attack risk. The xanthine oxidase theory has since fallen by the wayside, but there is now evidence that folic acid can lessen endothelial oxidative stress by improving the function of "uncoupled" nitric oxide synthase deficient in tetrahydrobiopterin. In light of these new findings, a properly controlled assessment of Oster's mega-dose folate therapy is warranted.
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27
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McCarty MF. High-dose folate may improve platelet function in acute coronary syndrome and other pathologies associated with increased platelet oxidative stress. Med Hypotheses 2007; 69:12-9. [PMID: 17293058 DOI: 10.1016/j.mehy.2004.08.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 08/13/2004] [Indexed: 11/27/2022]
Abstract
Although nitric oxide of endothelial origin plays a major role in warding off inappropriate thrombus formation, platelets also express the "constitutive" isoform of nitric oxide synthase (cNOS). Activation of this enzyme by calcium influx during platelet aggregation provides an important feedback signal that dampens platelet recruitment. Platelets also express a membrane-bound NAD(P)H oxidase complex, activated by collagen receptors, that produces superoxide. Superoxide can directly quench NO; moreover, by giving rise to peroxynitrite, it can oxidize the cNOS cofactor tetrahydrobiopterin (BH4), thereby suppressing cNOS activity and converting it to superoxide generator. In a canine model of acute coronary syndrome, infusion of BH4 has been shown to prevent thrombus formation. Platelets from patients with acute coronary syndrome produce markedly less NO than do control platelets. A reasonable explanation for these findings is that episodic contact with collagen boosts platelet superoxide production, oxidizing BH4. Since 5-methyltetrahydrofolate can reduce oxidized BH4, or otherwise compensate for its deficiency, supplementation with its precursor folic acid may improve platelet function in acute coronary syndrome and possibly reduce risk for coronary thrombosis in other at-risk patients. Other research demonstrates that superoxide production is increased, and nitric oxide production diminished, in platelets of diabetics; the ability of glutathione--a peroxynitrite scavenger--to largely ameliorate these abnormalities, is consistent with a prominent role for BH4 deficiency in diabetic platelet malfunction. Reports that platelet NO production is decreased, and/or superoxide production increased, in patients with disorders associated with insulin resistance syndrome, suggest that BH4 deficiency--potentially remediable with high-dose folate--may likewise contribute to the platelet hyperreactivity noted in these disorders. Supplemental vitamin C and arginine also have the potential to boost platelet production of NO Increased intakes of taurine, magnesium, gamma-tocopherol, fish oil, and garlic may help to stabilize platelets by additional mechanisms. As a complement to the proven benefits of low-dose aspirin, a supplemental regimen emphasizing these nutrients in appropriate doses may act directly on platelets to further diminish risk for thrombotic episodes.
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Affiliation(s)
- Mark F McCarty
- Natural Alternatives International, 1185 Linda Vista Road, San Marcos, CA 92078, USA.
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28
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Abstract
Tetrahydrobiopterin (BH4) is an essential cofactor for the aromatic amino acid hydroxylases, which are essential in the formation of neurotransmitters, and for nitric oxide synthase. It is presently used clinically to treat some forms of phenylketonuria (PKU) that can be ameliorated by BH4 supplementation. Recent evidence supports potential cardiovascular benefits from BH4 replacement for the treatment of hypertension, ischemia-reperfusion injury, and cardiac hypertrophy with chamber remodeling. Such disorders exhibit BH4 depletion because of its oxidation and/or reduced synthesis, which can result in functional uncoupling of nitric oxide synthase (NOS). Uncoupled NOS generates more oxygen free radicals and less nitric oxide, shifting the nitroso-redox balance and having adverse consequences on the cardiovascular system. While previously difficult to use as a treatment because of chemical instability and cost, newer methods to synthesize stable BH4 suggest its novel potential as a therapeutic agent. This review discusses the biochemistry, physiology, and evolving therapeutic potential of BH4 for cardiovascular disease.
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Affiliation(s)
- An L Moens
- Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, 720 Rutland Avenue, Baltimore, MD 21205, USA
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29
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Thöny B, Blau N. Mutations in the BH4-metabolizing genes GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase, carbinolamine-4a-dehydratase, and dihydropteridine reductase. Hum Mutat 2006; 27:870-8. [PMID: 16917893 DOI: 10.1002/humu.20366] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Tetrahydrobiopterin (BH(4)) deficiencies are a highly heterogeneous group of disorders with several hundred patients, and so far a total of 193 different mutant alleles or molecular lesions identified in the GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SR), carbinolamine-4a-dehydratase (PCD), or dihydropteridine reductase (DHPR) genes. The spectrum of mutations causing a reduction in one of the three biosynthetic (GTPCH, PTPS, and SR) or the two regenerating enzymes (PCD and DHPR) is tabulated and reviewed. Furthermore, current genomic variations or SNPs are also compiled. Mutations in GCH1 are scattered over the entire gene, and only 5 out of 104 mutant alleles, present in a homozygous state, are reported to cause the autosomal recessive form of inheritable hyperphenylalaninemia (HPA) associated with monoamine neurotransmitter deficiency. Almost all other 99 different mutant alleles in GCH1 are observed together with a wild-type allele and cause Dopa-responsive dystonia (DRD, Segawa disease) in a dominant fashion with reduced penetrance. Compound heterozygous or homozygous mutations are spread over the entire genes for PTS with 44 mutant alleles, for PCBD with nine mutant alleles, and for QDPR with 29 mutant alleles. These mutations cause an autosomal recessive inherited form of HPA, mostly accompanied by a deficiency of the neurotransmitters dopamine and serotonin. Lack of sepiapterin reductase activity, an autosomal recessive variant of BH(4) deficiency presenting without HPA, was diagnosed in patients with seven different mutant alleles in the SPR gene in exons 2 or 3 or in intron 2. Details on all mutations presented here are constantly updated in the BIOMDB database (www.bh4.org).
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Affiliation(s)
- Beat Thöny
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich, Switzerland
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30
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Hyland K. Cerebrospinal fluid analysis in the diagnosis of treatable inherited disorders of neurotransmitter metabolism. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.5.593] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The inherited disorders affecting dopamine and serotonin (5-hydroxytryptamine) metabolism are being recognized as treatable causes of neurological problems that affect infants, children and adults. Diagnosis of these conditions in many cases requires that neurotransmitter metabolites, and the cofactors required for their synthesis, be measured in cerebrospinal fluid (CSF). This review will concentrate on the inherited disorders that affect dopamine and serotonin biosynthesis and an overview will be given of the metabolism of these two neurotransmitters. The metabolite pattern found in each known defect is also given. Emphasis is put on the need to collect and handle CSF in the appropriate manner if meaningful results from neurotransmitter metabolite measurements are to be obtained. The clinical phenotypes that might be associated with neurotransmitter deficiency are described, and finally, speculation will be provided as to the metabolite patterns that might occur in the CSF in disorders that are yet to be discovered.
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Affiliation(s)
- Keith Hyland
- Horizon Molecular Medicine, One Dunwoody Park, Suite 250, Atlanta, GA 30338, USA
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31
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Moat SJ, Clarke ZL, Madhavan AK, Lewis MJ, Lang D. Folic acid reverses endothelial dysfunction induced by inhibition of tetrahydrobiopterin biosynthesis. Eur J Pharmacol 2006; 530:250-8. [PMID: 16387296 DOI: 10.1016/j.ejphar.2005.11.047] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 11/16/2005] [Accepted: 11/22/2005] [Indexed: 11/28/2022]
Abstract
While folic acid has been shown to reverse endothelial dysfunction, the exact underlying mechanism remains elusive. Here, folic acid reversed both the endothelial dysfunction and increased production of superoxide following depletion of rabbit aortic ring tetrahydrobiopterin (BH4) levels with 2,4-diamino-6-hydroxy-pyrimidine (DAHP) and N-acetyl-5-hydroxy-tryptamine (NAS). Incubation with l-nitroarginine methyl ester also attenuated the production of superoxide. DAHP and NAS reduced BH4 concentrations in both aorta and cultured porcine aortic endothelial cells. Folic acid had no effect on BH4 concentrations in either preparation. The superoxide anion scavenger Tiron but not folic acid reversed the endothelial dysfunction produced in aortic rings by inhibition of copper-zinc superoxide dismutase with diethyldithiocarbamic acid. Neither folic acid nor its metabolite 5-methyltetrahydrofolate prevented the in vitro oxidation of BH4. This study demonstrates that folic acid reverses the endothelial dysfunction induced by BH4 depletion independently of either the regeneration or stabilization of BH4 or an antioxidant effect.
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Affiliation(s)
- Stuart J Moat
- Department of Medical Biochemistry, University Hospital of Wales, Heath Park, Cardiff, CF14 4XN, United Kingdom
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McCarty MF. Adjuvant strategies for prevention of glomerulosclerosis. Med Hypotheses 2006; 67:1277-96. [PMID: 16828231 DOI: 10.1016/j.mehy.2004.11.048] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 11/29/2004] [Indexed: 12/23/2022]
Abstract
The glomerulosclerosis which frequently complicates diabetes and severe hypertension is mediated primarily by increased mesangial production and activation of transforming growth factor-beta (TGF-beta), which acts on mesangial cells to boost their production of matrix proteins while suppressing extracellular proteolytic activity. Hyperglycemia and glomerular hypertension work in various complementary ways to stimulate superoxide production via NADPH oxidase in mesangial cells; the resulting oxidant stress results in the induction and activation of TFG-beta. Nitric oxide, generated by glomerular capillaries and by mesangial cells themselves, functions physiologically to oppose mesangial TGF-beta overproduction; however, NO bioactivity is compromised by oxidant stress. In addition to low-protein diets and drugs that suppress angiotensin II activity, a variety of other agents and measures may have potential for impeding the process of glomerulosclerosis. These include vitamin E, which blunts the rise in mesangial diacylglycerol levels induced by hyperglycemia; statins and (possibly) policosanol, which down-regulate NADPH oxidase activity by diminishing isoprenylation of Rac1; lipoic acid, whose potent antioxidant activity antagonizes the impact of oxidant stress on TGF-beta expression; pyridoxamine, which inhibits production of advanced glycation endproducts; arginine, high-dose folate, vitamin C, and salt restriction, which may support glomerular production of nitric oxide; and estrogen and soy isoflavones, which may induce nitric oxide synthase in glomerular capillaries while also interfering with TGF-beta signaling. Further research along these lines may enable the development of complex nutraceuticals which have important clinical utility for controlling and preventing glomerulosclerosis and renal failure. Most of these measures may likewise reduce risk for left ventricular hypertrophy in hypertensives, inasmuch as the signaling mechanisms which mediate this disorder appear similar to those involved in glomerulosclerosis.
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Affiliation(s)
- Mark F McCarty
- NutriGuard Research, 1051 Hermes Ave., Encinitas, CA 92024, USA.
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Symons JD, Rutledge JC, Simonsen U, Pattathu RA. Vascular dysfunction produced by hyperhomocysteinemia is more severe in the presence of low folate. Am J Physiol Heart Circ Physiol 2005; 290:H181-91. [PMID: 16143648 DOI: 10.1152/ajpheart.00765.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Earlier we reported that dietary folate depletion causes hyperhomocysteinemia (HHcy) and arterial dysfunction in rats (Symons JD, Mullick AE, Ensunsa JL, Ma AA, and Rutledge JC. Arterioscler Thromb Vasc Biol 22: 772-780, 2002). Both HHcy and low folate (LF) are risk factors for cardiovascular disease. Therefore, the dysfunction we observed could have resulted from HHcy, LF, and/or their combination (HHcy + LF). We tested the hypothesis that HHcy-induced vascular dysfunction is more severe in the presence of LF. Four groups of rats consumed diets for approximately 10 wk that produced plasma homocysteine (microM) and liver folate (microg folate/g liver) concentrations, respectively, of 7 +/- 1 and 15 +/- 1 (Control; Con; n = 16), 17 +/- 2 and 15 +/- 2 (HHcy; n = 17), 10 +/- 1 and 8 +/- 1 (LF; n = 14), and 21 +/- 2 and 8 +/- 1 (HHcy + LF; n = 18). We observed that maximal ACh-evoked vasorelaxation was greatest in aortas and mesenteric arteries from Con rats vs. all groups. While the extent of dysfunction was similar between LF and HHcy animals, it was less severe compared with arteries from HHcy + LF rats. Maximal ACh-evoked vasorelaxation in coronary arteries was not different between Con and LF rats, but both were greater than HHcy + LF animals. In segments of aortas, 1) ACh-evoked vasorelaxation was similar among groups after incubation with the nonenzymatic intracellular O2(-) scavenger Tiron, 2) vascular O2(-) estimated using dihydroethidium staining was greatest in HHcy + LF vs. all groups, and 3) tension development in response to nitric oxide (NO) synthase inhibition was greatest in Con vs. all other groups. We conclude that HHcy + LF evokes greater dysfunction than either HHcy alone (aortas, mesentery) or LF alone (aortas, mesentery, coronary), likely by producing more O2(-) within the vasculature and thereby reducing NO bioavailability.
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Affiliation(s)
- J David Symons
- College of Health, Univ. of Utah, Salt Lake City, UT, USA.
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Abstract
Homocysteine is a sensitive marker of folate and vitamin B12 deficiency. Numerous studies have confirmed the association between folate deficiency and depression. It is not completely understood whether homocysteine is solely a marker for folate deficiency or if it may play a more direct role in the expression of mood disorders. This review describes the biochemical, neurochemical and clinical correlations of folate deficiency and hyperhomocysteinemia in relation to depression.
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Affiliation(s)
- Teodoro Bottiglieri
- Baylor University Medical Center, Institute of Metabolic Disease, Dallas, TX 75226, USA.
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Durga J, Verhoef P, Bots ML, Schouten E. Homocysteine and carotid intima-media thickness: a critical appraisal of the evidence. Atherosclerosis 2004; 176:1-19. [PMID: 15306169 DOI: 10.1016/j.atherosclerosis.2003.11.022] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Revised: 10/22/2003] [Accepted: 11/21/2003] [Indexed: 10/26/2022]
Abstract
UNLABELLED This review examines the relationship between hyperhomocysteinemia, a risk factor for vascular disease, and carotid intima-media thickness (CIMT), a valid marker of generalized atherosclerosis and future vascular disease risk. The relationship between two important determinants of hyperhomocysteinemia in the general population-folate status and the 677C --> T methylenetetrahydrofolate reductase (MTHFR) polymorphism-and CIMT is also covered. METHODS We searched literature databases for articles examining homocysteine and CIMT published before September 2003. RESULTS We identified 54 studies. Observational studies generally failed to demonstrate a relationship between homocysteine and CIMT in homocystinuric, uremic, hypercholesterolemic or non-insulin-dependent diabetes mellitus patients or in subjects with insulin insensitivity. Weak associations, but usually only in certain sub-populations were found in vascular disease patients and in population-based studies. B vitamins reduce the progression of CIMT in renal transplant recipients and vascular disease patients as demonstrated by two trials. The majority of studies demonstrated increased CIMT in individuals with the MTHFR 677TT genotype. Folate status showed no relation to CIMT. DISCUSSION In non-patient populations, hyperhomocysteinemia is weakly associated with CIMT. The association of the 677 C--> T MTHFR polymorphism with CIMT further supports this finding. Lastly, folate levels may need to reach a critically low status before an association can be found between folate and CIMT. Larger trials in various population types are needed to determine whether folate alone or in combination with Vitamins B6 and B12 will slow down or even reverse atherosclerotic progression.
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Affiliation(s)
- Jane Durga
- Division of Human Nutrition, Wageningen Centre for Food Sciences, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands.
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Taylor MJ, Carney SM, Goodwin GM, Geddes JR. Folate for depressive disorders: systematic review and meta-analysis of randomized controlled trials. J Psychopharmacol 2004; 18:251-6. [PMID: 15260915 DOI: 10.1177/0269881104042630] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The objective of this review was to determine the effectiveness, adverse effects and acceptability of folate in the treatment of depression. Electronic databases (Cochrane Controlled Trials Register and the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register) and reference lists were searched, and authors, experts and pharmaceutical companies contacted to identify randomized controlled trials that compared treatment with folic acid or 5'-methyltetrahydrofolic acid to an alternative treatment, for patients with a diagnosis of depressive disorder. Three randomized trials (247 participants) were included. Two studies assessed the use of folate in addition to other treatment, and found that adding folate reduced Hamilton Depression Rating Scale (HDRS) scores on average by a further 2.65 points [95% confidence interval (CI) 0.38-4.93]. Fewer patients treated with folate experienced a reduction in their HDRS score of less than 50% at 10 weeks (relative risk 0.47, 95% CI 0.24-0.92). The remaining study found no statistically significant difference when folate alone was compared with trazodone. The identified trials did not find evidence of any problems with the acceptability or safety of folate. The limited available evidence suggests folate may have a potential role as a supplement to other treatment for depression. It is currently unclear if this is the case both for people with normal folate levels, and for those with folate deficiency.
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Affiliation(s)
- Matthew J Taylor
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
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Beccia M, Mele MC, Ferrari M, Ranieri M, Barini A, Rasura M. Young stroke and basal plasma and post-methionine load homocysteine and cysteine levels 1 year after the acute event: do plasma folates make the difference? Eur J Neurol 2004; 11:269-75. [PMID: 15061829 DOI: 10.1046/j.1468-1331.2003.00774.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We conducted a case-control study to evaluate the relationship between ischemic stroke in young adults (<45 years of age) and plasma homocysteine (Hcy), plasma folate and vitamin B(12), after a methionine load. We studied 42 patients with a history of ischemic stroke and 29 controls with a negative clinical history of cardio- or cerebrovascular diseases, venous thrombosis and renal disease. A fasting blood sample was drawn from each participant; the second and third samples were collected, respectively, 120 and 240 min after the methionine load. Whilst there was no difference between controls and patients in basal total homocysteine (tHcy), we found a statistically significant difference in both the 120- and 240-min samples. We compared the basal and 240-min tHcy in patients and controls. We obtained a median value of 17.8 and 11.6 micromol/l in patients and controls, respectively. The difference between these two values was highly significant. The methionine loading test (MLT) reveals Hcy metabolism abnormalities that were not revealed by the basal sample. MLT may help identify and treat this new risk factor, which seems to be both atherogenic and prothrombotic, and is hypothesized to operate through various mechanisms.
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Affiliation(s)
- M Beccia
- Department of Neurological Sciences, II Faculty of Medicine, University of Rome 'La Sapienza', Rome, Italy.
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McCarty MF. Coping with endothelial superoxide: potential complementarity of arginine and high-dose folate. Med Hypotheses 2004; 63:709-18. [PMID: 15325022 DOI: 10.1016/j.mehy.2002.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 11/11/2002] [Indexed: 01/31/2023]
Abstract
Superoxide overproduction is a prominent mediator of the endothelial dysfunction associated with a range of vascular disorders, acting in a number of complementary ways to inhibit effective endothelial nitric oxide (NO) activity. The ability of superoxide to quench NO is well known, but oxidants derived from superoxide also appear to inhibit dimethylarginine dimethylaminohydrolase (DDAH) and to oxidize tetrahydrobiopterin (THBP). The former effect boosts the level of methylated arginines that act as potent competitive inhibitors of NO synthase, whereas the latter effect decreases the ability of this enzyme to generate NO, while converting it to a form that readily generates superoxide. The adverse impact of DDAH deficiency on NO production can be offset with supplemental arginine. Although supplementation with THBP has the potential to compensate for the rapid oxidative destruction of this compound, and maintaining optimal vitamin C nutrition may protect or restore the endothelial THBP pool to a limited extent, the most practical way to optimize NO synthase activity in the context of THBP deficit may be administration of high-dose folic acid. The primary circulating metabolite of folate, 5-methyltetrahydrofolate (5MTHF), is structurally analogous to THBP, and appears to normalize the activity of NO synthase in THBP-depleted endothelial cells, either because it "pinch hits" for the absent THBP, or interacts allosterically with NO synthase in some other way to promote the proper function of this enzyme. This observation may rationalize recent clinical studies showing a favorable effect of oral folic acid (5-10 mg daily) on dysfunctional endothelium, independent of any concurrent modulation of homocysteine levels. A recent study reports that, whereas either arginine or THBP alone have only a modest impact on dysfunctional aortic endothelium derived from hypercholesterolemic mice, the combination of the two produces a complete normalization of endothelial function. In aggregate, these considerations suggest that joint administration of arginine and high-dose folate may represent a fruitful approach to preventing and treating vascular disorders - albeit the underlying overproduction of superoxide should also be addressed by ameliorating relevant vascular risk factors.
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Affiliation(s)
- Mark F McCarty
- Pantox Laboratories, 4622 Santa Fe St., San Diego, CA 92109, USA.
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Blau N, Bonafé L, Krägeloh-Mann I, Thöny B, Kierat L, Häusler M, Ramaekers V. Cerebrospinal fluid pterins and folates in Aicardi-Goutières syndrome: a new phenotype. Neurology 2003; 61:642-7. [PMID: 12963755 DOI: 10.1212/01.wnl.0000082726.08631.e7] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To describe three unrelated children with a distinctive variant of Aicardi-Goutières syndrome (AGS) characterized by microcephaly, severe mental and motor retardation, dyskinesia or spasticity, and occasional seizures. RESULTS Neuroimaging showed bilateral calcification of basal ganglia and white matter. CSF glucose, protein, cell count, and interferon alpha were normal. Abnormal CSF findings included extremely high neopterin (293 to 814 nmol/L; normal 12 to 30 nmol/L) and biopterin (226 to 416 nmol/L; normal 15 to 40 nmol/L) combined with lowered 5-methyltetrahydrofolate (23 to 48 nmol/L; normal 64 to 182 nmol/L) concentrations in two patients. The absence of pleocytosis and normal CSF interferon alpha was a characteristic finding compared to the classic AGS syndrome. Genetic and enzymatic tests excluded disorders of tetrahydrobiopterin metabolism, including mutation analysis of GTP cyclohydrolase feed-back regulatory protein. CSF investigations in three patients with classic AGS also showed increased pterins and partially lowered folate levels. CONCLUSIONS Intrathecal overproduction of pterins is the first biochemical abnormality identified in patients with AGS variants. Long-term substitution with folinic acid (2-4 mg/kg/day) resulted in substantial clinical recovery with normalization of CSF folates and pterins in one patient and clinical improvement in another. The underlying defect remains unknown.
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Affiliation(s)
- N Blau
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich, Switzerland.
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40
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Pi J, Horiguchi S, Sun Y, Nikaido M, Shimojo N, Hayashi T, Yamauchi H, Itoh K, Yamamoto M, Sun G, Waalkes MP, Kumagai Y. A potential mechanism for the impairment of nitric oxide formation caused by prolonged oral exposure to arsenate in rabbits. Free Radic Biol Med 2003; 35:102-13. [PMID: 12826260 DOI: 10.1016/s0891-5849(03)00269-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have recently found evidence for impairment of nitric oxide (NO) formation and induction of oxidative stress in residents of an endemic area of chronic arsenic poisoning in Inner Mongolia, China. To investigate the underlying mechanisms responsible for these phenomena, a subchronic animal experiment was conducted using male New Zealand White rabbits. After 18 weeks of continuous exposure of rabbits to 5 mg/l of arsenate in drinking water, a significant decrease in systemic NO production occurred, as shown by significantly reduced plasma NO metabolites levels (76% of control) and a tendency towards decreased serum cGMP levels (81.4% of control). On the other hand, increased oxidative stress, as shown by significantly increased urinary hydrogen peroxide (H(2)O(2)) (120% of control), was observed in arsenate-exposed rabbits. In additional experiments measuring aortic tension, the addition of either the calcium ionophore A23187 or acethylcholine (ACh) induced a transient vasoconstriction of aortic rings prepared from arsenate-exposed rabbits, but not in those prepared from control animals. This calcium-dependent contractility action observed in aorta rings from arsenate-exposed rabbits was markedly attenuated by the superoxide (O2(.-)) scavenging enzyme Cu, Zn-SOD, as well as diphenyleneiodonium (DPI) or N(G)-nitro-L-arginine methyl ester (L-NAME), which are inhibitors for nitric oxide synthase (NOS). However, the cyclooxygenase inhibitor indomethacin or the xanthine oxidase blocker allopurinol had no effect on this vasoconstriction. These results suggest that arsenate-mediated reduction of systemic NO may be associated with the enzymatic uncoupling reaction of NOS with a subsequent enhancement of reactive oxygen species such as O2(.-), an endothelium-derived vasoconstricting factor. Furthermore, hepatic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH(4)), a cofactor for NOS, were markedly reduced in arsenate-exposed rabbits to 62% of control, while no significant change occurred in cardiac L-arginine levels. These results suggest that prolonged exposure of rabbits to oral arsenate may impair the bioavailability of BH(4) in endothelial cells and, as a consequence, disrupt the balance between NO and O2(.-) produced from endothelial NOS, such that enhanced free radicals are produced at the expense of NO.
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Affiliation(s)
- Jingbo Pi
- Graduate School Doctoral Program in Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
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Abstract
OBJECTIVES The possible link between folic acid or folate and tetrahydrobiopterin (H(4)B), vitamin C, polyunsaturated fatty acids (PUFAs), and nitric oxide (NO), which may explain the beneficial actions of these nutrients in various vascular conditions, was investigated. METHODS The literature pertaining to the actions of folic acid/folate, H(4)B, vitamin C, PUFAs, and NO was reviewed. RESULTS Impaired endothelial NO (eNO) activity is an early marker for cardiovascular disease. Most risk factors for atherosclerosis are associated with impaired endothelium-dependent vasodilatation due to reduced NO production. Folate not only reduces plasma homocysteine levels but also enhances eNO synthesis and shows anti-inflammatory actions. It stimulates endogenous H(4)B regeneration, a cofactor necessary for eNO synthesis, inhibits intracellular superoxide generation, and thus enhances the half-life of NO. H(4)B in turn enhances NO generation and augments arginine transport into the cells. Folic acid increases the concentration of omega-3 PUFAs, which also enhance eNO synthesis. Vitamin C augments eNO synthesis by increasing intracellular H(4)B and stabilization of H(4)B. Insulin stimulates H(4)B synthesis and PUFA metabolism, suppresses the production of proinflammatory cytokine tumor necrosis factor-alpha and superoxide anion, and enhances NO generation. The ability of folate to augment eNO generation is independent of its capacity to lower plasma homocysteine levels. CONCLUSIONS The common mechanism by which folic acid, H(4)B, vitamin C, omega-3 fatty acids, and L-arginine bring about their beneficial actions in various vascular diseases is by enhancing eNO production. Hence, it remains to be determined whether a judicious combination of folic acid, vitamins B12, B6, and C, H(4)B, L-arginine, and omega-3 fatty acids in appropriate amounts may form a novel approach in the prevention and management of various conditions such as hyperlipidemias, coronary heart disease, atherosclerosis, peripheral vascular disease, and some neurodegenerative conditions.
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Pannirselvam M, Anderson TJ, Triggle CR. Endothelial cell dysfunction in type I and II diabetes: The cellular basis for dysfunction. Drug Dev Res 2003. [DOI: 10.1002/ddr.10127] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Doshi S, McDowell I, Moat S, Lewis M, Goodfellow J. Folate Improves Endothelial Function in Patients with Coronary Heart Disease. Clin Chem Lab Med 2003; 41:1505-12. [PMID: 14656033 DOI: 10.1515/cclm.2003.231] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Elevated plasma homocysteine is associated with increased cardiovascular risk but it remains unproven that the effect is directly causal. Folate and homocysteine metabolism are closely linked such that administration of folic acid in doses ranging from 0.2-10 mg/day lowers plasma total homocysteine (tHcy) by up to 25%. Folic acid has been widely advocated as a therapy which may reduce cardiovascular risk, but the clinical benefit remains as yet unproven and the choice of dose remains unclear. The effect of folic acid on endothelial function has been investigated in patients with proven coronary heart disease (CHD) by measuring flow-mediated dilatation (FMD) in the brachial artery. Oral folic acid (5 mg/day) markedly enhances endothelial function (FMD) and lowers homocysteine. Studies of the acute effects of folic acid have shown that this improvement occurs within the first 2-4 hours following the first dose, at which times there was no significant reduction in plasma tHcy. Administration of 5-methyltetrahydrofolate directly into the brachial artery markedly enhances FMD, an effect that is blocked by monomethyl arginine (LNMMA), suggesting that the effects of folate are mediated by nitric oxide. This Review summarises studies which show that pharmacological doses of folate markedly enhance endothelial function in patients with CHD. The discordance with changes in plasma homocysteine suggests that these effects may occur by mechanisms distinct from homocysteine lowering.
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Affiliation(s)
- Sagar Doshi
- Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Cardiff, UK
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Abstract
BACKGROUND There are a number of effective interventions for the treatment of depression. It is possible that the efficacy of these treatments will be improved further by the use of adjunctive therapies such as folate. OBJECTIVES 1. To determine the effectiveness of folate in the treatment of depression 2. To determine the adverse effects and acceptability of treatment with folate. SEARCH STRATEGY The Cochrane Controlled Trials Register (CCTR), and the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register (CCDANCTR) incorporating results of group searches of EMBASE, MEDLINE, LILACS, CINAHL, PSYNDEX and PsycLIT were searched. Reference lists of relevant papers and major textbooks of affective disorder were checked. Experts in the field and pharmaceutical companies were contacted regarding unpublished material. SELECTION CRITERIA All randomised controlled trials that compared treatment with folic acid or 5'-methyltetrahydrofolic acid to an alternative treatment, whether another antidepressant medication or placebo, for patients with a diagnosis of depressive disorder (diagnosed according to explicit criteria). DATA COLLECTION AND ANALYSIS Data were independently extracted from the original reports by two reviewers. Statistical analysis was conducted using Review Manager version 4.1. MAIN RESULTS Three trials involving 247 people were included. Two studies involving 151 people assessed the use of folate in addition to other treatment, and found that adding folate reduced Hamilton Depression Rating Scale scores on average by a further 2.65 points (95% confidence interval 0.38 to 4.93). Fewer patients treated with folate experienced a reduction in their HDRS score of less than 50% at ten weeks (relative risk (RR) 0.47, 95% CI 0.24 to 0.92) The number needed to treat with folate for one additional person to experience a 50% reduction on this scale was 5 (95% confidence interval 4 to 33). One study involving 96 people assessed the use of folate instead of the antidepressant trazodone and did not find a significant benefit from the use of folate. The trials identified did not find evidence of any problems with the acceptability or safety of folate. REVIEWER'S CONCLUSIONS The limited available evidence suggests folate may have a potential role as a supplement to other treatment for depression. It is currently unclear if this is the case both for people with normal folate levels, and for those with folate deficiency.
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Affiliation(s)
- M J Taylor
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK, OX3 7JK.
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45
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Abstract
BACKGROUND An increased plasma level of homocysteine has been proposed as an independent risk factor for atherosclerosis; this review examines the evidence. METHODS A Medline search was undertaken for English language articles on homocysteine and vascular disease. Further papers were identified by cross-referencing from the reference lists of relevant major articles. RESULTS Although much interest has been generated about homocysteine and atherosclerotic disease, contradictory data exist regarding its role in disease progression. There is insufficient current evidence to regard increased homocysteine level as a causative factor in atherosclerotic disease. CONCLUSION It is not known whether lowering plasma homocysteine concentration will reduce cardiovascular risk in the long term. Until such data become available, there is no evidence for the widespread use of folic acid therapy to reduce cardiovascular disease risk.
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Affiliation(s)
- H O'Grady
- Department of Surgery, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland.
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46
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Abstract
It is increasingly recognized that folates may play a role in the prevention of cardiovascular disease. Over the last few years, several studies have reported beneficial effects of folates on endothelial function, a surrogate end point for cardiovascular risk. Consistently, observational studies have demonstrated an association between folate levels and cardiovascular morbidity and mortality. The exact mechanisms underlying the ameliorative effects of folates on the endothelium remain to be elucidated. Thus far, most studies have focused on the homocysteine-lowering effects of folates. However, recently, benefits of folates independent of homocysteine lowering have also been reported. Potential mechanisms include antioxidant actions, effects on cofactor availability, or direct interactions with the enzyme endothelial NO synthase. Obviously, beneficial effects of folates on cardiovascular risk would have important clinical and dietary consequences. However, for definite conclusions, the completion of ongoing randomized controlled trials will have to be awaited.
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Affiliation(s)
- M C Verhaar
- Department of Vascular Medicine, University Medical Centre Utrecht, Utrecht, the Netherlands.
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Bonafé L, Thöny B, Penzien JM, Czarnecki B, Blau N. Mutations in the sepiapterin reductase gene cause a novel tetrahydrobiopterin-dependent monoamine-neurotransmitter deficiency without hyperphenylalaninemia. Am J Hum Genet 2001; 69:269-77. [PMID: 11443547 PMCID: PMC1235302 DOI: 10.1086/321970] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2001] [Accepted: 05/31/2001] [Indexed: 11/03/2022] Open
Abstract
Classic tetrahydrobiopterin (BH(4)) deficiencies are characterized by hyperphenylalaninemia and deficiency of monoamine neurotransmitters. In this article, we report two patients with progressive psychomotor retardation, dystonia, severe dopamine and serotonin deficiencies (low levels of 5-hydroxyindoleacetic and homovanillic acids), and abnormal pterin pattern (high levels of biopterin and dihydrobiopterin) in cerebrospinal fluid. Furthermore, they presented with normal urinary pterins and without hyperphenylalaninemia. Investigation of skin fibroblasts revealed inactive sepiapterin reductase (SR), the enzyme catalyzing the final two-step reaction in the biosynthesis of BH(4). Mutations in the SPR gene were detected in both patients and their family members. One patient was homozygous for a TC-->CT dinucleotide exchange, predicting a truncated SR (Q119X). The other patient was a compound heterozygote for a genomic 5-bp deletion (1397-1401delAGAAC) resulting in abolished SPR-gene expression and an A-->G transition leading to an R150G amino acid substitution and to inactive SR as confirmed by recombinant expression. The absence of hyperphenylalaninemia and the presence of normal urinary pterin metabolites and of normal SR-like activity in red blood cells may be explained by alternative pathways for the final two-step reaction of BH(4) biosynthesis in peripheral and neuronal tissues. We propose that, for the biosynthesis of BH(4) in peripheral tissues, SR activity may be substituted by aldose reductase (AR), carbonyl reductase (CR), and dihydrofolate reductase, whereas, in the brain, only AR and CR are fully present. Thus, autosomal recessive SR deficiency leads to BH(4) and to neurotransmitter deficiencies without hyperphenylalaninemia and may not be detected by neonatal screening for phenylketonuria.
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Affiliation(s)
- Luisa Bonafé
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich; Children’s Hospital, Augsburg; and Children’s Hospital Königsborn, Unna, Germany
| | - Beat Thöny
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich; Children’s Hospital, Augsburg; and Children’s Hospital Königsborn, Unna, Germany
| | - Johann M. Penzien
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich; Children’s Hospital, Augsburg; and Children’s Hospital Königsborn, Unna, Germany
| | - Barbara Czarnecki
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich; Children’s Hospital, Augsburg; and Children’s Hospital Königsborn, Unna, Germany
| | - Nenad Blau
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich; Children’s Hospital, Augsburg; and Children’s Hospital Königsborn, Unna, Germany
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Doshi SN, McDowell IF, Moat SJ, Lang D, Newcombe RG, Kredan MB, Lewis MJ, Goodfellow J. Folate improves endothelial function in coronary artery disease: an effect mediated by reduction of intracellular superoxide? Arterioscler Thromb Vasc Biol 2001; 21:1196-202. [PMID: 11451751 DOI: 10.1161/hq0701.092000] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Homocysteine is a risk factor for coronary artery disease (CAD). Folic acid lowers homocysteine and may improve endothelial function in CAD, although the mechanism is unclear. We investigated the effect of folic acid on endothelial function, homocysteine, and oxidative stress in patients with CAD. We also examined the acute effect of 5-methyltetrahydrofolate (5-MTHF), the principal circulating folate, on endothelial function in vivo and on intracellular superoxide in cultured endothelial cells. A randomized crossover study of folic acid (5 mg daily) for 6 weeks was undertaken in 52 patients with CAD. Ten further patients were given intra-arterial 5-MTHF. Endothelial function was assessed by flow-mediated dilatation (FMD). Folic acid increased plasma folate (P<0.001), lowered homocysteine by 19% (P<0.001), and improved FMD (P<0.001). FMD improvement did not correlate with homocysteine reduction. Malondialdehyde and total plasma antioxidant capacity, markers of oxidative stress, were unchanged. 5-MTHF acutely improved FMD (P<0.001) without altering homocysteine (P=0.47). In vitro, 5-MTHF abolished homocysteine-induced intracellular superoxide increase (P<0.001); this effect was also observed with folic acid and tetrahydrobiopterin. Our data support the beneficial effect of folic acid on endothelial function in CAD but suggest that the mechanism is independent of homocysteine. Reduction of intracellular endothelial superoxide may have contributed to the effect.
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Affiliation(s)
- S N Doshi
- Department of Pharmacology, Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff, UK
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Abstract
Metabolism is one of the corner stones of nutritional science. As biology enters the post-genomic era and with functional genomics beginning to takeoff, we anticipate that the study of metabolism will play an increasingly important role in helping to link advances made via the reductionist paradigm, that has been so successful in molecular and cellular biology, with those emerging from observational studies in animals and human subjects. A reconstructive metabolically-focused approach offers a timely paradigm for enhancing the elegance of nutritional science. Here we give particular attention to the use of tracers as phenotyping tools and discuss the application of our metaprobe concepts with respect to some novel features of metabolism, including 'underground metabolism', 'metabolic hijacking', 'catalytic promiscuity' and 'moonlighting proteins'. The opportunities for enhancing the study of metabolism by new and emerging technologies, and the importance of the interdisciplinary research enterprise are also touched upon. We conclude that: (1) the metaprobe concepts and approach, discussed herein, potentially yield a quantitative physiological (metabolic) phenotype against which to elaborate partial or focused genotypes; (2) physiological (metabolic) phenotypes which have a whole-body or kinetically-discernible inter-organ tissue-directed metabolic signature are an ideal target for this directed tracer-based definition of the 'functional' genotype; (3) metabolism, probed with tracer tool kits suitable for measuring rates of turnover, change and conversion, becomes in the current sociology of the 'Net', like AOL, Yahoo. Alta Vista, Lycos or Ask Jeeves, the portal for an exploration of the metabolic characteristics of the 'Genomics Internet'.
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Affiliation(s)
- V R Young
- Laboratory of Human Nutrition, School of Science and Clinical Research Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Hyndman ME, Bridge PJ, Warnica JW, Fick G, Parsons HG. Effect of heterozygosity for the methionine synthase 2756 A-->G mutation on the risk for recurrent cardiovascular events. Am J Cardiol 2000; 86:1144-6, A9. [PMID: 11074217 DOI: 10.1016/s0002-9149(00)01177-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Increased dietary intake of folate has been shown to significantly reduce the risk for fatal myocardial infarction, possibly by lowering homocysteine levels. We therefore investigated the association between recurrent cardiovascular events and a mutation in methionine synthase (2756 A-->G)--an enzyme directly involved in folate and homocysteine metabolism. This mutation significantly reduced the risk for recurrent cardiovascular events and elevated red blood cell folate levels.
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Affiliation(s)
- M E Hyndman
- Department of Medical Genetics, University of Calgary, Alberta, Canada
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