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Ryan A, Twomey PJ. Homocystinuria: a commentary. J Clin Pathol 2023; 76:153-155. [PMID: 36460459 DOI: 10.1136/jcp-2022-208606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/15/2022] [Indexed: 12/03/2022]
Affiliation(s)
- Aidan Ryan
- Chemical Pathology, Cork University Hospital Biochemistry Laboratory, Cork, Ireland .,Pathology, University College Cork College of Medicine and Health, Cork, Ireland
| | - Patrick J Twomey
- Clinical Chemistry, St Vincent's University Hospital, Dublin, Ireland.,University College Dublin School of Medicine and Medical Science, Dublin, Ireland
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Gerrard A, Dawson C. Homocystinuria diagnosis and management: it is not all classical. J Clin Pathol 2022; 75:jclinpath-2021-208029. [PMID: 36123115 DOI: 10.1136/jcp-2021-208029] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/02/2022] [Indexed: 11/04/2022]
Abstract
Homocystinuria (HCU) refers to a group of inherited disorders of homocysteine metabolism associated with high blood homocysteine concentration, thromboembolic tendency and neurocognitive symptoms. The most common causes of a high blood homocysteine relate to underlying vitamin B12 or folate deficiency which must be excluded first. Thereafter, an inherited metabolic condition can be considered.The most prevalent inherited disorder of homocysteine metabolism is classical HCU caused by deficiency of the pyridoxine-dependent enzyme, cystathione beta-synthase, which converts homocysteine to cystathionine in the transsulphuration pathway. An alternative route for homocysteine metabolism is its remethylation to methionine by the cobalamin-dependent enzyme, methionine synthase, using the folate derivative, methyltetrahydrofolate, as a methyl donor. Remethylation defects are caused by impaired activity of methionine synthase itself, of an enzyme required to generate its methylcobalamin cofactor from dietary vitamin B12, or of the enzyme methyltetrahydrofolate reductase (MTHFR), which generates the methyl donor.The correct diagnosis can be inferred from additional laboratory investigations including a complete blood count and quantitation of methionine and methylmalonic acid. Methionine is high/normal in HCU and low in the remethylation disorders. In the latter, cobalamin defects are readily distinguished from MTHFR by a coexisting macrocytic anaemia and further delineated by presence or absence of methylmalonic acid in urine or plasma.Lowering homocysteine reverses thromboembolic risk. In HCU, this may be achieved with pyridoxine alone or with betaine as an alternative methyl donor. Some patients additionally follow a methionine-restricted diet. Betaine is the primary treatment for MTHFR and cobalamin disorders are managed with high-dose hydroxocobalamin.
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Affiliation(s)
- Adam Gerrard
- Department of Clinical Chemistry, Birmingham Women's and Children's Hospitals NHS Foundation Trust, Birmingham, UK
| | - Charlotte Dawson
- Department of Endocrinology and Metabolism, Queen Elizabeth Hospital Birmingham, Birmingham, UK
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Rahman M, Sharma M, Aggarwal P, Singla S, Jain N. Homocystinuria and ocular complications - A review. Indian J Ophthalmol 2022; 70:2272-2278. [PMID: 35791106 PMCID: PMC9426183 DOI: 10.4103/ijo.ijo_309_22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Homocystinuria is a rare metabolic inborn disorder caused due to dysfunctional cystathionine β-synthase (CBS) enzyme activity, thus resulting in elevated levels of methionine and homocysteine in the blood and urine. The timely recognition of this rare metabolic disorder and prompt methionine-restricted diet are crucial in lessening the systemic consequences. The recalcitrant cases have a higher risk for cardiovascular diseases, neurodegenerative diseases, neural tube defects, and other severe clinical complications. This review aims to present the ophthalmic spectrum of homocystinuria and its molecular basis, the disease management, as well as the current and potential treatment approaches with a greater emphasis on preventive strategies.
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Affiliation(s)
- Mehzabeen Rahman
- Department of Ophthalmology, Tirupati Eye Center, Noida, Uttar Pradesh, India
| | - Mohita Sharma
- Department of Ophthalmology, Tirupati Eye Center, Noida, Uttar Pradesh, India
| | - Pragati Aggarwal
- Department of Ophthalmology, Tirupati Eye Center, Noida, Uttar Pradesh, India
| | - Silkee Singla
- Department of Ophthalmology, Tirupati Eye Center, Noida, Uttar Pradesh, India
| | - Neha Jain
- Department of Ophthalmology, Tirupati Eye Center, Noida, Uttar Pradesh, India
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Mikaliunaite L, Green DB. Using a 3-hydroxyflavone derivative as a fluorescent probe for the indirect determination of aminothiols separated by ion-pair HPLC. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:2915-2925. [PMID: 34109341 DOI: 10.1039/d1ay00499a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Homocysteine, cysteine, cysteinyl-glycine, and glutathione are significant biological aminothiols (ATs) that are marker-molecules in Down syndrome, Alzheimer's disease, or have been implicated as risk factors in atherosclerosis and other vascular diseases, and therefore rapid determination of these molecules is desirable. After reduction of the disulfides, a widely used method utilizes derivatization with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F) as a fluorogenic probe prior to reversed-phase HPLC separation followed by fluorescence detection. The traditional HPLC determination of ATs is time consuming and economically expensive. We have developed an ion-pair HPLC method coupled with indirect fluorescence detection after post-column reaction with a 2,4-dinitrobenzenesulfonate derivative of a 3-hydroxyflavone. The accuracy, precision, post-column temperature and residence time, and limit-of-detection were evaluated. Sample throughput and reduced sample preparation time of over an hour for the existing methods to less than 20 minutes for the new method is also demonstrated. No statistical differences in HCy, Cys, or Cys-Gly determinations in plasma samples were observed between our method and the traditional HPLC method.
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Affiliation(s)
- Lina Mikaliunaite
- Department of Chemistry, Pepperdine University, Malibu, CA 90263, USA.
| | - David B Green
- Department of Chemistry, Pepperdine University, Malibu, CA 90263, USA.
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Kožich V, Sokolová J, Morris AAM, Pavlíková M, Gleich F, Kölker S, Krijt J, Dionisi‐Vici C, Baumgartner MR, Blom HJ, Huemer M. Cystathionine β-synthase deficiency in the E-HOD registry-part I: pyridoxine responsiveness as a determinant of biochemical and clinical phenotype at diagnosis. J Inherit Metab Dis 2021; 44:677-692. [PMID: 33295057 PMCID: PMC8247016 DOI: 10.1002/jimd.12338] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/27/2020] [Accepted: 12/07/2020] [Indexed: 11/23/2022]
Abstract
Cystathionine β-synthase (CBS) deficiency has a wide clinical spectrum, ranging from neurodevelopmental problems, lens dislocation and marfanoid features in early childhood to adult onset disease with predominantly thromboembolic complications. We have analysed clinical and laboratory data at the time of diagnosis in 328 patients with CBS deficiency from the E-HOD (European network and registry for Homocystinurias and methylation Defects) registry. We developed comprehensive criteria to classify patients into four groups of pyridoxine responsivity: non-responders (NR), partial, full and extreme responders (PR, FR and ER, respectively). All groups showed overlapping concentrations of plasma total homocysteine while pyridoxine responsiveness inversely correlated with plasma/serum methionine concentrations. The FR and ER groups had a later age of onset and diagnosis and a longer diagnostic delay than NR and PR patients. Lens dislocation was common in all groups except ER but the age of dislocation increased with increasing responsiveness. Developmental delay was commonest in the NR group while no ER patient had cognitive impairment. Thromboembolism was the commonest presenting feature in ER patients, whereas it was least likely at presentation in the NR group. This probably is due to the differences in ages at presentation: all groups had a similar number of thromboembolic events per 1000 patient-years. Clinical severity of CBS deficiency depends on the degree of pyridoxine responsiveness. Therefore, a standardised pyridoxine-responsiveness test in newly diagnosed patients and a critical review of previous assessments is indispensable to ensure adequate therapy and to prevent or reduce long-term complications.
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Affiliation(s)
- Viktor Kožich
- Department of Pediatrics and Inherited Metabolic DisordersCharles University‐First Faculty of Medicine and General University Hospital in PraguePragueCzech Republic
| | - Jitka Sokolová
- Department of Pediatrics and Inherited Metabolic DisordersCharles University‐First Faculty of Medicine and General University Hospital in PraguePragueCzech Republic
| | - Andrew A. M. Morris
- Manchester Centre for Genomic MedicineManchester University Hospitals NHS TrustManchesterUK
| | - Markéta Pavlíková
- Department of Probability and Mathematical StatisticsCharles University‐Faculty of Mathematics and PhysicsPragueCzech Republic
| | - Florian Gleich
- Division of Neuropaediatrics and Metabolic Medicine, Centre for Paediatric and Adolescent MedicineUniversity HospitalHeidelbergGermany
| | - Stefan Kölker
- Division of Neuropaediatrics and Metabolic Medicine, Centre for Paediatric and Adolescent MedicineUniversity HospitalHeidelbergGermany
| | - Jakub Krijt
- Department of Pediatrics and Inherited Metabolic DisordersCharles University‐First Faculty of Medicine and General University Hospital in PraguePragueCzech Republic
| | - Carlo Dionisi‐Vici
- Division of MetabolismBambino Gesù Children's Research Hospital, IRCCSRomeItaly
| | - Matthias R. Baumgartner
- Division of Metabolism and Children's Research CenterUniversity Children's HospitalZurichSwitzerland
- University of ZürichZürichSwitzerland
| | - Henk J. Blom
- Department of Clinical Genetics, Center for Lysosomal and Metabolic DiseasesErasmus Medical CenterRotterdamNetherlands
| | - Martina Huemer
- Division of Metabolism and Children's Research CenterUniversity Children's HospitalZurichSwitzerland
- Department of PediatricsLandeskrankenhaus BregenzBregenzAustria
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6
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Morris AAM, Kožich V, Santra S, Andria G, Ben-Omran TIM, Chakrapani AB, Crushell E, Henderson MJ, Hochuli M, Huemer M, Janssen MCH, Maillot F, Mayne PD, McNulty J, Morrison TM, Ogier H, O'Sullivan S, Pavlíková M, de Almeida IT, Terry A, Yap S, Blom HJ, Chapman KA. Guidelines for the diagnosis and management of cystathionine beta-synthase deficiency. J Inherit Metab Dis 2017; 40:49-74. [PMID: 27778219 PMCID: PMC5203861 DOI: 10.1007/s10545-016-9979-0] [Citation(s) in RCA: 184] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/11/2016] [Accepted: 09/12/2016] [Indexed: 12/17/2022]
Abstract
Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 μmol/L. Nevertheless, we recommend keeping the concentration below 100 μmol/L because levels fluctuate and the complications associated with high levels are so serious.
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Affiliation(s)
- Andrew A M Morris
- Institute of Human Development, University of Manchester, Manchester, UK.
- Willink Unit, Manchester Centre for Genomic Medicine, Central Manchester University Hospitals, St Mary's Hospital, Oxford Road, Manchester, M13 9WL, UK.
| | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, Charles University in Prague-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Saikat Santra
- Clinical IMD, Birmingham Children's Hospital, Birmingham, UK
| | - Generoso Andria
- Department of translational medicine, Federico II University, Naples, Italy
| | | | | | - Ellen Crushell
- National Centre for Inherited Metabolic Disorders, Temple Street Children's University Hospital, Dublin, Ireland
| | - Mick J Henderson
- Willink Unit, Manchester Centre for Genomic Medicine, Central Manchester University Hospitals, St Mary's Hospital, Oxford Road, Manchester, M13 9WL, UK
- Biochemical Genetics, St James' University Hospital, Leeds, UK
| | - Michel Hochuli
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital Zürich, Zurich, Switzerland
| | - Martina Huemer
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, Zurich, Switzerland
- Rare Disease Initiative Zürich, University of Zürich, Zurich, Switzerland
- Dept. of Paediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria
| | - Miriam C H Janssen
- Department of Internal medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - Philip D Mayne
- Newborn Bloodspot Screening Laboratory, Temple Street Children's University Hospital, Dublin, Ireland
| | - Jenny McNulty
- National Centre for Inherited Metabolic Disorders, Temple Street Children's University Hospital, Dublin, Ireland
| | | | - Helene Ogier
- Service de Neurologie Pédiatrique et des Maladies Métaboliques, Hôpital Robert Debré, Paris, France
| | | | - Markéta Pavlíková
- Institute of Inherited Metabolic Disorders, Charles University in Prague-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | | | - Allyson Terry
- Institute of Human Development, University of Manchester, Manchester, UK
- Dietetic Department, Alder Hey Hospital, Liverpool, UK
| | - Sufin Yap
- Dept of Inherited Metabolic Diseases, Sheffield Children's Hospital, Sheffield, UK
| | - Henk J Blom
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, University Medical Centre Freiburg, Freiburg im Breisgau, Germany
| | - Kimberly A Chapman
- Division of Genetic and Metabolism, Children's National Health System, Washington, DC, USA
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Huemer M, Diodato D, Schwahn B, Schiff M, Bandeira A, Benoist JF, Burlina A, Cerone R, Couce ML, Garcia-Cazorla A, la Marca G, Pasquini E, Vilarinho L, Weisfeld-Adams JD, Kožich V, Blom H, Baumgartner MR, Dionisi-Vici C. Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency. J Inherit Metab Dis 2017; 40:21-48. [PMID: 27905001 PMCID: PMC5203859 DOI: 10.1007/s10545-016-9991-4] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/28/2016] [Accepted: 10/04/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions. OBJECTIVE To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management. DATA SOURCES Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach. KEY RECOMMENDATIONS We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.
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Affiliation(s)
- Martina Huemer
- Division of Metabolism and Children's Research Center, University Childrens' Hospital Zürich, Zurich, Switzerland
- radiz - Rare Disease Initiative Zürich, Clinical Research Priority Program, University of Zürich, Zurich, Switzerland
- Department of Paediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria
| | - Daria Diodato
- Division of Metabolism, Bambino Gesù Children's Research Hospital, Rome, Italy
| | - Bernd Schwahn
- Willink Biochemical Genetics Unit, Saint Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Manuel Schiff
- Reference Center for Inborn Errors of Metabolism, Robert Debré University Hospital, APHP, Paris, France
- Inserm U1141, Robert Debré Hospital, Paris, France
- Université Paris-Diderot, Sorbonne Paris Cité, site Robert Debré, Paris, France
| | | | - Jean-Francois Benoist
- Reference Center for Inborn Errors of Metabolism, Robert Debré University Hospital, APHP, Paris, France
- Inserm U1141, Robert Debré Hospital, Paris, France
- Biochimie, faculté de pharmacie, Université Paris Sud, Paris, France
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Pediatrics, University Hospital Padova, Padova, Italy
| | - Roberto Cerone
- University Dept of Pediatrics, Giannina Gaslini Institute, Genoa, Italy
| | - Maria L Couce
- Congenital Metabolic Diseases Unit, Hospital Clínico Universitario de Santiago de Compostela, IDIS, CIBER, Compostela, Spain
| | - Angeles Garcia-Cazorla
- Department of Neurology, Neurometabolism Unit, and CIBERER (ISCIII), Hospital Sant Joan de Deu, Barcelona, Spain
| | - Giancarlo la Marca
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firence, Italy
| | - Elisabetta Pasquini
- Metabolic and Newborn Screening Clinical Unit, Department of Neurosciences, A. Meyer Children's University Hospital, Florence, Italy
| | - Laura Vilarinho
- Newborn Screening, Metabolism & Genetics Unit, National Institute of Health, Porto, Portugal
| | - James D Weisfeld-Adams
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Inherited Metabolic Diseases Clinic, Childrens Hospital Colorado, Aurora, CO, USA
| | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic
| | - Henk Blom
- Laboratory of Clinical Biochemistry and Metabolism, Center for Pediatrics and Adolescent Medicine University Hospital, Freiburg, Freiburg, Germany
| | - Matthias R Baumgartner
- Division of Metabolism and Children's Research Center, University Childrens' Hospital Zürich, Zurich, Switzerland.
- radiz - Rare Disease Initiative Zürich, Clinical Research Priority Program, University of Zürich, Zurich, Switzerland.
| | - Carlo Dionisi-Vici
- Division of Metabolism, Bambino Gesù Children's Research Hospital, Rome, Italy.
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D'Souza SW, Solanky N, Guarino J, Moat S, Sibley CP, Taggart M, Glazier JD. Human Placental Arterial Distensibility, Birth Weight, and Body Size Are Positively Related to Fetal Homocysteine Concentration. Reprod Sci 2016; 24:1070-1078. [PMID: 27879450 DOI: 10.1177/1933719116678694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Methionine demethylation during metabolism generates homocysteine (Hcy) and its remethylation requires folate and cobalamin. Elevated Hcy concentrations are associated with vascular-related complications of pregnancy, including increased vascular stiffness, predictive of clinical vascular disease. Maternal and fetal total Hcy (tHcy) concentrations are positively related, yet the influence of Hcy on fetoplacental vascular function in normal pregnancy has not been examined. We hypothesized that Hcy alters fetoplacental vascular characteristics with influences on fetal growth outcomes. We investigated (1) placental chorionic plate artery distensibility and neonatal blood pressure in relation to umbilical plasma tHcy; (2) relationships between cord venous (CV) and cord arterial (CA) plasma tHcy, folate, and cobalamin concentrations; and (3) tHcy associations with birth weight and anthropometric measurements of body size as indices of fetal growth in normal pregnancies with appropriate weight-for-gestational age newborns. Maternal plasma tHcy, folate, and cobalamin concentrations were consistent with published data. Placental chorionic plate artery distensibility index (β; measure of vessel stiffness) was inversely related to CA tHcy, yet neonatal blood pressure was not significantly affected. CV and CA tHcy concentrations were positively related and CV tHcy negatively related to CV cobalamin but not folate. CV tHcy concentration positively related to birth weight, corrected birth weight percentile, length, head circumference, and mid-arm circumference of newborns. CV cobalamin was inversely related to fetal growth indices but not to folate concentration. Our study demonstrates a potential relationship between fetal tHcy and placental artery distensibility, placing clinical relevance to cobalamin in influencing Hcy concentration and maintaining low vascular resistance to facilitate nutrient exchange favorable to fetal growth.
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Affiliation(s)
- Stephen W D'Souza
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, St Mary's Hospital, Manchester, UK
| | - Nita Solanky
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, St Mary's Hospital, Manchester, UK
| | - Jane Guarino
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, St Mary's Hospital, Manchester, UK
| | - Stuart Moat
- 2 Department of Medical Biochemistry and Immunology, University Hospital of Wales and Cardiff School of Medicine, Cardiff University, Heath Park, Cardiff, United Kingdom
| | - Colin P Sibley
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, St Mary's Hospital, Manchester, UK
| | - Michael Taggart
- 3 Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle, United Kingdom
| | - Jocelyn D Glazier
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, St Mary's Hospital, Manchester, UK
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Fischer S, Huemer M, Baumgartner M, Deodato F, Ballhausen D, Boneh A, Burlina AB, Cerone R, Garcia P, Gökçay G, Grünewald S, Häberle J, Jaeken J, Ketteridge D, Lindner M, Mandel H, Martinelli D, Martins EG, Schwab KO, Gruenert SC, Schwahn BC, Sztriha L, Tomaske M, Trefz F, Vilarinho L, Rosenblatt DS, Fowler B, Dionisi-Vici C. Clinical presentation and outcome in a series of 88 patients with the cblC defect. J Inherit Metab Dis 2014; 37:831-40. [PMID: 24599607 DOI: 10.1007/s10545-014-9687-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 01/27/2014] [Accepted: 01/30/2014] [Indexed: 12/17/2022]
Abstract
UNLABELLED The cblC defect is the most common inborn error of vitamin B12 metabolism. Despite therapeutic measures, the long-term outcome is often unsatisfactory. This retrospective multicentre study evaluates clinical, biochemical and genetic findings in 88 cblC patients. The questionnaire designed for the study evaluates clinical and biochemical features at both initial presentation and during follow up. Also the development of severity scores allows investigation of individual disease load, statistical evaluation of parameters between the different age of presentation groups, as well as a search for correlations between clinical endpoints and potential modifying factors. RESULTS No major differences were found between neonatal and early onset patients so that these groups were combined as an infantile-onset group representing 88 % of all cases. Hypotonia, lethargy, feeding problems and developmental delay were predominant in this group, while late-onset patients frequently presented with psychiatric/behaviour problems and myelopathy. Plasma total homocysteine was higher and methionine lower in infantile-onset patients. Plasma methionine levels correlated with "overall impression" as judged by treating physicians. Physician's impression of patient's well-being correlated with assessed disease load. We confirmed the association between homozygosity for the c.271dupA mutation and infantile-onset but not between homozygosity for c.394C>T and late-onset. Patients were treated with parenteral hydroxocobalamin, betaine, folate/folinic acid and carnitine resulting in improvement of biochemical abnormalities, non-neurological signs and mortality. However the long-term neurological and ophthalmological outcome is not significantly influenced. In summary the survey points to the need for prospective studies in a large cohort using agreed treatment modalities and monitoring criteria.
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Affiliation(s)
- Sabine Fischer
- University Children's Hospital Basel, Spitalstrasse 33, Basel, 4506, Switzerland
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10
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Adam S, Almeida MF, Carbasius Weber E, Champion H, Chan H, Daly A, Dixon M, Dokoupil K, Egli D, Evans S, Eyskens F, Faria A, Ferguson C, Hallam P, Heddrich-Ellerbrok M, Jacobs J, Jankowski C, Lachmann R, Lilje R, Link R, Lowry S, Luyten K, MacDonald A, Maritz C, Martins E, Meyer U, Müller E, Murphy E, Robertson LV, Rocha JC, Saruggia I, Schick P, Stafford J, Stoelen L, Terry A, Thom R, van den Hurk T, van Rijn M, van Teefelen-Heithoff A, Webster D, White FJ, Wildgoose J, Zweers H. Dietary practices in pyridoxine non-responsive homocystinuria: a European survey. Mol Genet Metab 2013; 110:454-9. [PMID: 24206934 DOI: 10.1016/j.ymgme.2013.10.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 10/05/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Within Europe, the management of pyridoxine (B6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice. AIM A comparison of dietetic management practices of patients with B6 non-responsive HCU in European centres. METHODS A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium). RESULTS 181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n=119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n=62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and >16 years, 45 g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20 g; and >16 years, 38 g. Fifty-two percent (n=15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free l-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied. CONCLUSION In B6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines.
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Affiliation(s)
- S Adam
- Glasgow Royal Infirmary, Royal Hospital for Sick Children, UK
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11
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Moat SJ. Plasma total homocysteine: instigator or indicator of cardiovascular disease? Ann Clin Biochem 2008; 45:345-8. [DOI: 10.1258/acb.2008.008053] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cardiovascular disease (CVD) is a major cause of morbidity and mortality in developed countries. However, traditional risk factors cannot fully account for this. In the last 20 years, there has been an explosion of interest in plasma total homocysteine (tHcy) as a potential modifiable risk factor for CVD. Recent meta-analyses of epidemiological studies support the concept that increased tHcy concentrations are associated with CVD. This has led to the ‘homocysteine hypothesis’, which states that lowering plasma tHcy using folic acid and other B-vitamins will reduce the risk of CVD. In experimental studies, homocysteine has been shown to cause oxidative stress, endothelial cell dysfunction and promote thrombogenesis. However, data from recent large randomized controlled trials have shown that there is no clinical benefit to lowering plasma tHcy concentrations with folic acid and other B-vitamins. This lack of effect of tHcy lowering strongly suggests that homocysteine is not an instigator but merely an indicator of CVD.
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Affiliation(s)
- Stuart J Moat
- Department of Medical Biochemistry and Immunology, University Hospital of Wales and Wales College of Medicine, Heath Park, Cardiff CF14 4XW, UK
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12
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Shirodaria C, Antoniades C, Lee J, Jackson CE, Robson MD, Francis JM, Moat SJ, Ratnatunga C, Pillai R, Refsum H, Neubauer S, Channon KM. Global improvement of vascular function and redox state with low-dose folic acid: implications for folate therapy in patients with coronary artery disease. Circulation 2007; 115:2262-70. [PMID: 17420345 DOI: 10.1161/circulationaha.106.679084] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Although dietary folate fortification lowers plasma homocysteine and may reduce cardiovascular risk, high-dose folic acid therapy appears to not alter clinical outcome. Folic acid and its principal circulating metabolite, 5-methyltetrahydrofolate, improve vascular function, but mechanisms relating folate dose to vascular function remain unclear. We compared the effects of folic acid on human vessels using pharmacological high-dose versus low-dose treatment, equivalent to dietary folate fortification. METHODS AND RESULTS Fifty-six non-folate-fortified patients with coronary artery disease were randomized to receive low-dose (400 microg/d) or high-dose (5 mg/d) folic acid or placebo for 7 weeks before coronary artery bypass grafting. Vascular function was quantified by magnetic resonance imaging before and after treatment. Vascular superoxide and nitric oxide bioavailability were determined in segments of saphenous vein and internal mammary artery. Low-dose folic acid increased nitric oxide-mediated endothelium-dependent vasomotor responses, reduced vascular superoxide production, and improved enzymatic coupling of endothelial nitric oxide synthase through availability of the cofactor tetrahydrobiopterin. No further improvement in these parameters occurred with high-dose compared with low-dose treatment. Whereas plasma 5-methyltetrahydrofolate increased proportionately with treatment dose of folic acid, vascular tissue 5-methyltetrahydrofolate showed no further increment with high-dose compared with low-dose folic acid. CONCLUSIONS Low-dose folic acid treatment, comparable to daily intake and dietary fortification, improves vascular function through effects on endothelial nitric oxide synthase and vascular oxidative stress. High-dose folic acid treatment provides no additional benefit. These direct vascular effects are related to vascular tissue levels of 5-methyltetrahydrofolate rather than plasma levels. High-dose folic acid treatment likely confers no further benefit in subjects already receiving folate supplementation.
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Affiliation(s)
- Cheerag Shirodaria
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
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13
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Lee PJ, Briddon A. A rationale for cystine supplementation in severe homocystinuria. J Inherit Metab Dis 2007; 30:35-8. [PMID: 17186416 DOI: 10.1007/s10545-006-0452-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 11/30/2006] [Accepted: 12/01/2006] [Indexed: 10/23/2022]
Abstract
Previous studies have shown that the thiol redox, as measured by the ratio of free/bound cyst(e)ine in unaffected individuals, remains relatively constant. In severe homocystinuria (HCU) where cyst(e)ine moieties are significantly reduced, this redox is only restored when homocyst(e)ine moieties are also taken into account. This appears to stem from an increase in the free/bound homocyst(e)ine ratio with free homocystine acting as a surrogate for free cystine. We examined these ratios in 47 patients (two with a cobalamin C defect, two with methylenetetrahydrofolate reductase deficiency, 16 with pyridoxine-responsive HCU and 27 with pyridoxine-nonresponsive HCU). Comparing free/bound homocyst(e)ine ratios to the total cysteine concentration indicates a relative increase of free homocystine as total cysteine concentrations fall below 170 micromol/L. This provides a rationale and treatment algorithm for cyst(e)ine supplementation in homocystinuria.
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Affiliation(s)
- P J Lee
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
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14
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Clarke ZL, Moat SJ, Miller AL, Randall MD, Lewis MJ, Lang D. Differential effects of low and high dose folic acid on endothelial dysfunction in a murine model of mild hyperhomocysteinaemia. Eur J Pharmacol 2006; 551:92-7. [PMID: 17045583 DOI: 10.1016/j.ejphar.2006.08.085] [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: 05/16/2006] [Revised: 08/22/2006] [Accepted: 08/31/2006] [Indexed: 01/29/2023]
Abstract
The exact mechanism(s) by which hyperhomocysteinaemia promotes vascular disease remains unclear. Moreover, recent evidence suggests that the beneficial effect of folic acid on endothelial function is independent of homocysteine-lowering. In the present study the effect of a low (400 microg/70 kg/day) and high (5 mg/70 kg/day) dose folic acid supplement on endothelium-dependent relaxation in the isolated perfused mesenteric bed of heterozygous cystathionine beta-synthase deficient mice was investigated. Elevated total plasma homocysteine and impaired relaxation responses to methacholine were observed in heterozygous mice. In the presence of N(G)-nitro-L-arginine methyl ester relaxation responses in wild-type tissues were reduced, but in heterozygous tissues were abolished. Clotrimazole and 18alpha-glycyrrhetinic acid, both inhibitors of non-nitric oxide/non-prostanoid-induced endothelium-dependent relaxation, reduced responses to methacholine in wild-type but not heterozygous tissues. The combination of N(G)-nitro-L-arginine methyl ester and either clotrimazole or 18alpha-glycyrrhetinic acid completely inhibited relaxation responses in wild-type tissues. Both low and high dose folic acid increased plasma folate, reduced total plasma homocysteine and reversed endothelial dysfunction in heterozygous mice. A greater increase in plasma folate in the high dose group was accompanied by a more significant effect on endothelial function. In the presence of N(G)-nitro-L-arginine methyl ester, a significant residual relaxation response was evident in tissues from low and high dose folic acid treated heterozygous mice. These data suggest that the impaired mesenteric relaxation in heterozygous mice is largely due to loss of the non-nitric oxide/non-prostanoid component. While low dose folic acid may restore this response in a homocysteine-dependent manner, the higher dose has an additional effect on nitric oxide-mediated relaxation that would appear to be independent of homocysteine lowering.
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Affiliation(s)
- Zoe L Clarke
- Wales Heart Research Institute, Wales College of Medicine, Cardiff University, Heath Park Campus, Cardiff, CF14 4XN, United Kingdom
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15
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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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16
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Doshi S, McDowell I, Goodfellow J, Stabler S, Boger R, Allen R, Newcombe R, Lewis M, Moat S. Relationship between S-adenosylmethionine, S-adenosylhomocysteine, asymmetric dimethylarginine, and endothelial function in healthy human subjects during experimental hyper- and hypohomocysteinemia. Metabolism 2005; 54:351-60. [PMID: 15736113 DOI: 10.1016/j.metabol.2004.09.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Experimental hyperhomocysteinemia after an oral methionine or homocysteine load is associated with impaired nitric oxide-dependent vasodilatation in healthy human beings. However, it remains unproven that this effect is mediated by elevations in plasma homocysteine. There is evidence that an increase in plasma homocysteine may increase the formation of asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxide synthase. The methyl groups within ADMA are derived from the conversion of S -adenosylmethionine to S -adenosylhomocysteine intermediates in the methionine/homocysteine pathway. No previous study has assessed the role of methylation status, its impact on ADMA formation, and their association with endothelial function in healthy human beings. In a randomized, placebo-controlled, crossover study, 10 healthy subjects (mean age, 29.1 +/- 3.9 years) were administered an oral dose of methionine (0.1 g/kg), l -homocysteine (0.01 g/kg), N-acetylcysteine (NAC) (0.1 g/kg), or placebo. Endothelial function as assessed by flow-mediated dilatation (FMD) of the brachial artery was impaired after both the methionine and homocysteine load compared with placebo at 4 hours (36 +/- 15, 67 +/- 23 vs 219 +/- 26 microm, respectively, P < .001). N-Acetylcysteine had no effect on flow-mediated dilatation. Plasma total homocysteine was significantly elevated at 4 hours after methionine (23.1 +/- 6.2) and homocysteine (41.5 +/- 8.9) loading, but significantly reduced after NAC 2.4 +/- 0.6 vs 7.1 +/- 2.1 micromol/L in the placebo (P < .001). Plasma S-adenosylmethionine/S-adenosylhomocysteine ratio was significantly (P < .001) increased at 4 hours after methionine (10.9 +/- 0.7) compared with homocysteine (5.4 +/- 0.4), NAC (5.0 +/- 0.3), and placebo (6.0 +/- 0.5). Plasma ADMA concentrations were not altered by any intervention. Our results suggest that endothelial dysfunction due to methionine or homocysteine loading is not associated with an increase in plasma ADMA or a disruption in methylation status.
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Affiliation(s)
- Sagar Doshi
- Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Heath Park CF14 4XN Cardiff, UK
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17
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Nakano E, Taiwo FA, Nugent D, Griffiths HR, Aldred S, Paisi M, Kwok M, Bhatt P, Hill MHE, Moat S, Powers HJ. Downstream effects on human low density lipoprotein of homocysteine exported from endothelial cells in an in vitro system. J Lipid Res 2005; 46:484-93. [PMID: 15576841 DOI: 10.1194/jlr.m400339-jlr200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A model system is presented using human umbilical vein endothelial cells (HUVECs) to investigate the role of homocysteine (Hcy) in atherosclerosis. HUVECs are shown to export Hcy at a rate determined by the flux through the methionine/Hcy pathway. Additional methionine increases intracellular methionine, decreases intracellular folate, and increases Hcy export, whereas additional folate inhibits export. An inverse relationship exists between intracellular folate and Hcy export. Hcy export may be regulated by intracellular S-adenosyl methionine rather than by Hcy. Human LDLs exposed to HUVECs exporting Hcy undergo time-related lipid oxidation, a process inhibited by the thiol trap dithionitrobenzoate. This is likely to be related to the generation of hydroxyl radicals, which we show are associated with Hcy export. Although Hcy is the major oxidant, cysteine also contributes, as shown by the effect of glutamate. Finally, the LDL oxidized in this system showed a time-dependent increase in uptake by human macrophages, implying an upregulation of the scavenger receptor. These results suggest that continuous export of Hcy from endothelial cells contributes to the generation of extracellular hydroxyl radicals, with associated oxidative modification of LDL and incorporation into macrophages, a key step in atherosclerosis. Factors that regulate intracellular Hcy metabolism modulate these effects.
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Affiliation(s)
- E Nakano
- Human Nutrition Unit, University of Sheffield, Coleridge House, The Northern General Hospital, Sheffield S5 7AU, United Kingdom
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18
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Moat SJ, Lang D, McDowell IFW, Clarke ZL, Madhavan AK, Lewis MJ, Goodfellow J. Folate, homocysteine, endothelial function and cardiovascular disease. J Nutr Biochem 2004; 15:64-79. [PMID: 14972346 DOI: 10.1016/j.jnutbio.2003.08.010] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2003] [Revised: 08/19/2003] [Accepted: 08/25/2003] [Indexed: 10/26/2022]
Abstract
Evidence reported from numerous clinical studies over the past decade has revealed an association between increased plasma total homocysteine (tHcy) concentrations and cardiovascular disease (CVD). In addition, epidemiological studies have identified an inverse association between blood folate concentrations, folate intake and cardiovascular endpoints, that are independent of homocysteine. Folic acid supplementation can lower plasma tHcy concentrations safely and inexpensively. Furthermore, folic acid can reverse endothelial dysfunction observed in patients with CVD. This reversal in endothelial dysfunction with folic acid has been shown to be independent of plasma tHcy lowering, suggesting that folate has pleiotropic effects on the vasculature other than homocysteine lowering. In vitro evidence demonstrates that 5-methyltetrahydrofolate (5MeTHF) the main circulating metabolite of folate, can increase nitric oxide production and can directly scavenge superoxide radicals. The potential beneficial role of folic acid supplements on vascular disease are currently being tested in randomized placebo controlled studies.
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Affiliation(s)
- Stuart J Moat
- Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Cardiff, UK.
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19
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Harvey Mudd S, Braverman N, Pomper M, Tezcan K, Kronick J, Jayakar P, Garganta C, Ampola MG, Levy HL, McCandless SE, Wiltse H, Stabler SP, Allen RH, Wagner C, Borschel MW. Infantile hypermethioninemia and hyperhomocysteinemia due to high methionine intake: a diagnostic trap. Mol Genet Metab 2003; 79:6-16. [PMID: 12765841 DOI: 10.1016/s1096-7192(03)00066-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Studies were carried out to identify the cause of combined severe hypermethioninemia and moderate hyperhomocysteinemia in a cluster of 10 infants ascertained between 1999 and early 2001. Although several were thought initially to have cystathionine beta-synthase (CBS) deficiency and treated accordingly, CBS deficiency and other known genetic causes of hypermethioninemia were ruled out by assay of CBS activity in fibroblasts of four patients and by assays of plasma cystathionine and S-adenosylmethionine. Retrospective data on dietary methionine intakes and plasma concentrations of methionine and related metabolites established that the hypermethioninemia in nine of the 10 babies was related to ingestion of an infant protein hydrolysate formula, the methionine content of which had been increased from May 1998 to February 2001. The formula in question has now been reformulated and is no longer available. The 10th infant manifested similar metabolic abnormalities while receiving TPN containing excessive methionine. Brain MRI abnormalities indicative of cerebral edema, most marked in the cerebral cortex and posterior brainstem, occurred in two patients near times of extreme hypermethioninemia. Metabolic and MRI abnormalities resolved when the methionine intake decreased. A third infant had a normal MRI 1 day after the formula was changed. The possible relationship between extreme hypermethioninemia and cerebral edema is discussed and a working hypothesis offered to explain the relative sensitivity of the inferior colliculi, based upon the facts that this is the region most active in glucose utilization and that Na(+),K(+)-ATPase is inhibited by methionine and related metabolites.
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Affiliation(s)
- S Harvey Mudd
- NIMH/DIRP/LMB, Laboratory of Molecular Biology, National Institute of Mental Health, Building 36, Room 1B-08, 36 Convent Drive, MSC 4034, Bethesda, MD 20892-4034, USA.
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20
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Moat SJ, Hill MH, McDowell IFW, Pullin CH, Ashfield-Watt PAL, Clark ZE, Whiting JM, Newcombe RG, Lewis MJ, Powers HJ. Reduction in plasma total homocysteine through increasing folate intake in healthy individuals is not associated with changes in measures of antioxidant activity or oxidant damage. Eur J Clin Nutr 2003; 57:483-9. [PMID: 12627187 DOI: 10.1038/sj.ejcn.1601554] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2001] [Revised: 06/14/2002] [Accepted: 06/18/2002] [Indexed: 11/08/2022]
Abstract
BACKGROUND Various mechanisms have been proposed to explain the association between plasma total homocysteine (tHcy) and risk of cardiovascular disease, including oxidative activity of homocysteine. OBJECTIVE To explore the putative role of reactive oxygen species in the association between plasma tHcy and risk of cardiovascular disease in healthy individuals. DESIGN A double-blind, placebo-controlled crossover intervention to increase folate intake through diet (increased consumption of folate-rich foods) and supplement (400 micro g folic acid) was carried out in 126 healthy men and women. Measurements were made of antioxidant activity in red blood cells and plasma, and products of oxidant damage in plasma. RESULTS Diet and supplement-based interventions led to an increase in measures of folate status and a reduction in plasma tHcy. This was not associated with any significant change in measures of antioxidant activity (plasma and red blood cell glutathione peroxidase activity and red blood cell superoxide dismutase activity) or oxidant damage (plasma malondialdehyde), although an improvement in plasma total antioxidant capacity just failed to reach significance. CONCLUSIONS In healthy individuals lowering plasma tHcy does not have any functional implications regarding oxidative damage.
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Affiliation(s)
- S J Moat
- The Centre for Human Nutrition, University of Sheffield, The Northern General Hospital, UK
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21
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Matthews A, Johnson TN, Rostami-Hodjegan A, Chakrapani A, Wraith JE, Moat SJ, Bonham JR, Tucker GT. An indirect response model of homocysteine suppression by betaine: optimising the dosage regimen of betaine in homocystinuria. Br J Clin Pharmacol 2002; 54:140-6. [PMID: 12207633 PMCID: PMC1874404 DOI: 10.1046/j.1365-2125.2002.01620.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2001] [Accepted: 04/09/2002] [Indexed: 11/20/2022] Open
Abstract
AIMS To investigate the pharmacokinetics (PK) and pharmacodynamics (PD) of betaine in the treatment of classical homocystinuria due to cystathionine beta-synthase (CbetaS) deficiency with a view to optimizing the dosage regimen. METHODS Betaine was given as a single oral dose of 100 mg kg(-1) to six patients (age range 6-17 years) who normally received betaine but whose treatment had been suspended for 1 week prior to the study. Plasma betaine and total homocysteine concentrations were measured by high performance liquid chromatography (h.p.l.c.) at frequent intervals over 24 h. The best-fit PK model was determined using the PK-PD program Win-Nonlin and the concentration-time-effect data analysed by an indirect PD model. Using the PK and PD parameters, simulations were carried out with the aim of optimizing betaine dosage. RESULTS Betaine PK was described by both mono- and bi-exponential disposition functions with first order absorption and a lag time. The correlation coefficient between betaine oral clearance and body weight was 0.6. Mean betaine clearance was higher in males than in females (P=0.03). PK-PD simulation indicated minimal benefit from exceeding a twice-daily dosing schedule and a 150 mg kg(-1) day(-1) dosage for betaine. CONCLUSIONS PK-PD modelling allows recommendations for optimal dosage of betaine in the treatment of homocystinuria, that have the potential for improved patient compliance and both therapeutic and pharmacoeconomic benefit.
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Affiliation(s)
- Angela Matthews
- Department of Chemical Pathology & Neonatal Screening, Sheffield Children's Hospital, Manchester, UK
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22
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Pullin CH, Bonham JR, McDowell IFW, Lee PJ, Powers HJ, Wilson JF, Lewis MJ, Moat SJ. Vitamin C therapy ameliorates vascular endothelial dysfunction in treated patients with homocystinuria. J Inherit Metab Dis 2002; 25:107-18. [PMID: 12118525 DOI: 10.1023/a:1015672625913] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVES We sought to investigate the effects of short- and long-term vitamin C therapy on endothelial dysfunction in patients with homocystinuria. BACKGROUND Untreated homocystinuria due to cystathionine beta-synthase deficiency is associated with premature atherothrombotic disease; 25% of untreated patients suffer a vascular event by the age of 16 years and 50% by 29 years. Treatment directed at reducing homocysteine accumulation significantly reduces this risk. However, despite 'optimal' treatment and compliance, hyperhomocysteinaemia usually persists and individuals exhibit endothelial dysfunction indicative of an adverse cardiovascular prognosis. Additional intervention is therefore required to further reduce cardiovascular risk. METHODS We investigated the endothelial effects of acute (2 g single dose) and chronic (1 g/day for 6 months) administration of oral vitamin C in 5 patients with homocystinuria (mean age 26 years, 1 male) and 5 age- and sex-matched controls. Brachial artery endothelium-dependent flow-mediated dilatation (FMD) and endothelium-independent responses to nitroglycerin (NTG) were measured using high-resolution ultrasonic vessel wall-tracking. RESULTS Baseline: Plasma total homocysteine was 100.8 +/- 61.6 and 9.2 +/- 1.9 micromol/L in the patient and control groups, respectively (p < 0.001). FMD responses were impaired in the patient group (20 +/- 40 microm) compared with the controls (116 +/- 30 microm) (p < 0.001). Vitamin C administration: FMD responses in the patient group improved both acutely, 160 +/- 65 microm at 4 h (p < 0.001), and chronically, 170 +/- 70 microm at 2 weeks (p < 0.001) and 170 +/- 40 microm at 6 months (p < 0.001). FMD responses in the control group were unaltered (p = 0.526). Within both groups, neither the vascular response to NTG nor plasma homocysteine was altered (p > 0.4). CONCLUSIONS Vitamin C ameliorates endothelial dysfunction in patients with homocystinuria, independent of changes in homocysteine concentration and should therefore be considered as an additional adjunct to therapy to reduce the potential long-term risk of atherothrombotic disease.
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Affiliation(s)
- C H Pullin
- Cardiovascular Sciences Research Group, Wales Heart Research Institute, Cardiff, UK
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Davis KR, Pearson H, Moat S, Bonham JR, Donnelly R. Acute hyperhomocysteinaemia affects pulse pressure but not microvascular vasodilator function. Br J Clin Pharmacol 2001; 52:327-32. [PMID: 11560567 PMCID: PMC2014549 DOI: 10.1046/j.0306-5251.2001.01447.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS Raised homocysteine (hcy) levels are associated with premature coronary artery disease, but the underlying vascular mechanism and the extent to which hcy affects small vessel vasodilator responses (especially non-nitric oxide mediated pathways) are unclear. METHODS This double-blind, placebo-controlled crossover study in 14 healthy male subjects evaluated the effects of single-dose oral methionine 15 g (to induce acute hyperhomocysteinaemia) on cutaneous microvascular vasodilator responses to incremental-dose iontophoretic administration of acetylcholine (Ach) and sodium nitroprusside (SNP) using laser Doppler fluximetry (LDF), and the effects on von Willibrand factor (vWF) levels and systemic haemodynamics. RESULTS Methionine administration produced a three fold rise in plasma hcy levels at 8 h, which was accompanied by a significant increase in pulse pressure (53 vs 49 mmHg, P < 0.05) but no change in heart rate. Acute hyperhomocysteinaemia had no significant effect on incremental microvascular vasodilator dose-response curves to Ach and SNP, or circulating levels of vWF. CONCLUSIONS The present study shows that acute hyperhomocysteinaemia increases pulse pressure (a marker of large vessel stiffness) but has no effect on endothelial-dependent (non-NO-mediated) microvascular vasodilation.
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Affiliation(s)
- K R Davis
- School of Medical and Surgical Sciences, University of Nottingham, UK
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Abstract
Elevated plasma homocysteine is considered to be a graded risk factor for cardiovascular disease, and for this reason there is great interest in high-performance analytical techniques. Methods have evolved from ion-exchange chromatography to embrace high-performance liquid chromatography with fluorescence or electrochemical detection, immunoassays, gas chromatography-mass spectroscopy and liquid chromatography with tandem mass spectrometry. Immunoassays and high-performance liquid chromatography methods are currently available in kit form, fluorescence polarization immunoassay showing the best performance.
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Affiliation(s)
- H J Powers
- The Centre for Human Nutrition, Division of Clinical Sciences, University of Sheffield, Sheffield, UK.
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