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Allegri G, Deplazes S, Grisch-Chan HM, Mathis D, Fingerhut R, Häberle J, Thöny B. A simple dried blood spot-method for in vivo measurement of ureagenesis by gas chromatography-mass spectrometry using stable isotopes. Clin Chim Acta 2016; 464:236-243. [PMID: 27923571 DOI: 10.1016/j.cca.2016.11.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/07/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Clinical management of inherited or acquired hyperammonemia depends mainly on the plasma ammonia level which is not a reliable indicator of urea cycle function as its concentrations largely fluctuate. The gold standard to assess ureagenesis in vivo is the use of stable isotopes. METHODS Here we developed and validated a simplified in vivo method with [15N]ammonium chloride ([15N]H4Cl) as a tracer. Non-labeled and [15N]urea were quantified by GC-MS after extraction and silylation. RESULTS Different matrices were evaluated for suitability of analysis. Ureagenesis was assessed in ornithine transcarbamylase (OTC)-deficient spfash mice with compromised urea cycle function during fasted and non-fasted feeding states, and after rAAV2/8-vector delivery expressing the murine OTC-cDNA in liver. Blood (5μL) was collected through tail vein puncture before and after [15N]H4Cl intraperitoneal injections over a two hour period. The tested matrices, blood, plasma and dried blood spots, can be used to quantify ureagenesis. Upon [15N]H4Cl challenge, urea production in spfash mice was reduced compared to wild-type and normalized following rAAV2/8-mediated gene therapeutic correction. The most significant difference in ureagenesis was at 30min after injection in untreated spfash mice under fasting conditions (19% of wild-type). Five consecutive injections over a period of five weeks had no effect on body weight or ureagenesis. CONCLUSION This method is simple, robust and with no apparent risk, offering a sensitive, minimal-invasive, and fast measurement of ureagenesis capacity using dried blood spots. The stable isotope-based quantification of ureagenesis can be applied for the efficacy-testing of novel molecular therapies.
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Affiliation(s)
- Gabriella Allegri
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland
| | - Sereina Deplazes
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland
| | - Hiu Man Grisch-Chan
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland
| | - Déborah Mathis
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Switzerland
| | - Ralph Fingerhut
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland; Swiss Newborn Screening Laboratory, University Children's Hospital Zurich, Switzerland
| | - Johannes Häberle
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland; Zurich Centre for Integrative Human Physiology (ZIHP) and the Neuroscience Centre Zurich (ZNZ), Zurich, Switzerland
| | - Beat Thöny
- Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Switzerland; Zurich Centre for Integrative Human Physiology (ZIHP) and the Neuroscience Centre Zurich (ZNZ), Zurich, Switzerland.
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2
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Opladen T, Lindner M, Das AM, Marquardt T, Khan A, Emre SH, Burton BK, Barshop BA, Böhm T, Meyburg J, Zangerl K, Mayorandan S, Burgard P, Dürr UHN, Rosenkranz B, Rennecke J, Derbinski J, Yudkoff M, Hoffmann GF. In vivo monitoring of urea cycle activity with (13)C-acetate as a tracer of ureagenesis. Mol Genet Metab 2016; 117:19-26. [PMID: 26597322 DOI: 10.1016/j.ymgme.2015.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/12/2015] [Accepted: 11/12/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND The hepatic urea cycle is the main metabolic pathway for detoxification of ammonia. Inborn errors of urea cycle function present with severe hyperammonemia and a high case fatality rate. Long-term prognosis depends on the residual activity of the defective enzyme. A reliable method to estimate urea cycle activity in-vivo does not exist yet. The aim of this study was to evaluate a practical method to quantify (13)C-urea production as a marker for urea cycle function in healthy subjects, patients with confirmed urea cycle defect (UCD) and asymptomatic carriers of UCD mutations. METHODS (13)C-labeled sodium acetate was applied orally in a single dose to 47 subjects (10 healthy subjects, 28 symptomatic patients, 9 asymptomatic carriers). RESULTS The oral (13)C-ureagenesis assay is a safe method. While healthy subjects and asymptomatic carriers did not differ with regards to kinetic variables for urea cycle flux, symptomatic patients had lower (13)C-plasma urea levels. Although the (13)C-ureagenesis assay revealed no significant differences between individual urea cycle enzyme defects, it reflected the heterogeneity between different clinical subgroups, including male neonatal onset ornithine carbamoyltransferase deficiency. Applying the (13)C-urea area under the curve can differentiate between severe from more mildly affected neonates. Late onset patients differ significantly from neonates, carriers and healthy subjects. CONCLUSION This study evaluated the oral (13)C-ureagenesis assay as a sensitive in-vivo measure for ureagenesis capacity. The assay has the potential to become a reliable tool to differentiate UCD patient subgroups, follow changes in ureagenesis capacity and could be helpful in monitoring novel therapies of UCD.
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Affiliation(s)
- Thomas Opladen
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany.
| | - Martin Lindner
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany; Division of Neuropaediatrics, Prevention, Endocrinology and Pediatric Metabolic Diseases, University Children's Hospital Frankfurt, Germany.
| | - Anibh M Das
- Division of Metabolic Disorders, Medical School Hannover, Germany.
| | - Thorsten Marquardt
- Division of Metabolic Disorders, University Children's Hospital Münster, Germany.
| | - Aneal Khan
- Department of Medical Genetics & Pediatrics, Alberta Children's Hospital, Calgary, Canada.
| | - Sukru H Emre
- Department of Surgery, Yale University School of Medicine, New Haven, USA.
| | | | - Bruce A Barshop
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA.
| | - Thea Böhm
- Cytonet GmbH & Co. KG, Albert-Ludwig-Grimm-Str. 20, Weinheim, Germany.
| | - Jochen Meyburg
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany.
| | - Kathrin Zangerl
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany.
| | | | - Peter Burgard
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany.
| | - Ulrich H N Dürr
- Cytonet GmbH & Co. KG, Albert-Ludwig-Grimm-Str. 20, Weinheim, Germany.
| | - Bernd Rosenkranz
- Division of Clinical Pharmacology, Faculty of Medicine and Health Sciences, Department of Medicine, Stellenbosch University, South Africa.
| | - Jörg Rennecke
- Cytonet GmbH & Co. KG, Albert-Ludwig-Grimm-Str. 20, Weinheim, Germany.
| | - Jens Derbinski
- Cytonet GmbH & Co. KG, Albert-Ludwig-Grimm-Str. 20, Weinheim, Germany.
| | - Marc Yudkoff
- Division of Metabolic Disease, Children's Hospital of Philadelphia, USA.
| | - Georg F Hoffmann
- Division of Neuropediatrics and Pediatric Metabolic Medicine, University Children's Hospital Heidelberg, Germany.
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3
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- Inborn Errors of Amino Acid Metabolism. Amino Acids 2013. [DOI: 10.1201/b14661-16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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4
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Cunningham SC, Spinoulas A, Carpenter KH, Wilcken B, Kuchel PW, Alexander IE. AAV2/8-mediated correction of OTC deficiency is robust in adult but not neonatal Spf(ash) mice. Mol Ther 2009; 17:1340-6. [PMID: 19384294 PMCID: PMC2835243 DOI: 10.1038/mt.2009.88] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Accepted: 03/30/2009] [Indexed: 11/08/2022] Open
Abstract
Ornithine transcarbamylase (OTC) deficiency, the most common urea cycle disorder, is associated with severe hyperammonemia accompanied by a high risk of neurological damage and death in patients presenting with the neonatal-onset form. Contemporary therapies, including liver transplantation, remain inadequate with considerable morbidity, justifying vigorous investigation of alternate therapies. Clinical evidence suggests that as little as 3% normal enzyme activity is sufficient to ameliorate the severe neonatal phenotype, making OTC deficiency an ideal model for the development of liver-targeted gene therapy. In this study, we investigated metabolic correction in neonatal and adult male OTC-deficient Spf(ash) mice following adeno-associated virus (AAV)2/8-mediated delivery of the murine OTC complementary DNA under the transcriptional control of a liver-specific promoter. Substantially supraphysiological levels of OTC enzymatic activity were readily achieved in both adult and neonatal mice following a single intraperitoneal (i.p.) injection, with metabolic correction in adults being robust and life-long. In the neonates, however, full metabolic correction was transient, although modest levels of OTC expression persisted into adulthood. Although not directly testable in Spf(ash) mice, these levels were theoretically sufficient to prevent hyperammonemia in a null phenotype. This loss of expression in the neonatal liver is the consequence of hepatocellular proliferation and presents an added challenge to human therapy.
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Affiliation(s)
- Sharon C Cunningham
- Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Wentworthville, New South Wales, Australia
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5
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Deardorff MA, Gaddipati H, Kaplan P, Sanchez-Lara PA, Sondheimer N, Spinner NB, Hakonarson H, Ficicioglu C, Ganesh J, Markello T, Loechelt B, Zand DJ, Yudkoff M, Lichter-Konecki U. Complex management of a patient with a contiguous Xp11.4 gene deletion involving ornithine transcarbamylase: a role for detailed molecular analysis in complex presentations of classical diseases. Mol Genet Metab 2008; 94:498-502. [PMID: 18524659 PMCID: PMC2572572 DOI: 10.1016/j.ymgme.2008.04.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 04/14/2008] [Accepted: 04/14/2008] [Indexed: 02/04/2023]
Abstract
A male infant was diagnosed prenatally with a partial ornithine transcarbamylase (OTC) gene deletion and managed from birth. However, he displayed neurological abnormalities and developed pleural effusions, ascites and anasarca not solely explained by OTC deficiency (OTCD). Further evaluation of the gene locus using exon-specific PCR and high-density SNP array copy number analysis revealed a 3.9-Mb deletion from Xp11.4 to Xp21.1 including five additional gene deletions, three causing the known genetic diseases: Retinitis pigmentosa (RP3), X-linked chronic granulomatous disease (CGD) and McLeod syndrome. The case illustrates (1) the complexities of managing a patient with neonatal onset OTCD, CGD, RP3 and McLeod syndrome, (2) the need for detailed evaluation in seemingly "isolated" gene deletions and (3) the clinical utility of high-density copy number analysis for rapidly characterizing chromosomal lesions.
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Affiliation(s)
- Matthew A. Deardorff
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Section of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Himabindu Gaddipati
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Section of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Paige Kaplan
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Pedro A. Sanchez-Lara
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Section of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Neal Sondheimer
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Nancy B. Spinner
- Section of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Hakon Hakonarson
- Section of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Center for Applied Genomics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Can Ficicioglu
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Jaya Ganesh
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Thomas Markello
- Division of Genetics and Metabolism, Children's National Medical Center, Washington, DC
| | - Brett Loechelt
- Division of Stem Cell Transplantation & Immunology, Children's National Medical Center, Washington, DC
| | - Dina J. Zand
- Division of Genetics and Metabolism, Children's National Medical Center, Washington, DC
| | - Marc Yudkoff
- Section of Metabolic Diseases, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Uta Lichter-Konecki
- Division of Genetics and Metabolism, Children's National Medical Center, Washington, DC
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Banta-Wright SA, Steiner RD. Not so rare: errors of metabolism during the neonatal period. ACTA ACUST UNITED AC 2003. [DOI: 10.1053/s1527-3369(03)00116-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Trinh MU, Blake J, Harrison JR, Gerace R, Ranieri E, Fletcher JM, Johnson DW. Quantification of glutamine in dried blood spots and plasma by tandem mass spectrometry for the biochemical diagnosis and monitoring of ornithine transcarbamylase deficiency. Clin Chem 2003; 49:681-4. [PMID: 12651832 DOI: 10.1373/49.4.681] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Minh-Uyen Trinh
- Department of Chemical Pathology, Women's and Children's Hospital, 72 King William Rd., North Adelaide, South Australia 5006, Australia
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Abstract
Urea-cycle disorders (UCDs) are a group of inborn errors of hepatocyte metabolism that are caused by the loss of enzymes involved in the process of transferring nitrogen from ammonia to urea, via the urea cycle (UC). Recent genetic analyses of inherited disorders that present with hyperammonemia demonstrate the function of cellular transporters that regulate the availability of UC intermediates. The regulation of UC intermediates, such as arginine, could have far reaching implications on nitric-oxide synthesis and vascular tone. Hence, each UCD and UC-related disorder constitutes a unique gene-nutrient interaction that is crucial for postnatal homeostasis. Recent advances in the diagnosis and management of UCDs include the application of in vivo metabolic-flux measurements. Cumulative morbidity is still high despite dietary and pharmacological therapies and, hence, both cell and gene therapies are being pursued as possible long-term corrective treatments. Although gene-replacement therapy has suffered recent clinical setbacks, new vector developments offer hope for the treatment of cell-autonomous defects of hepatocyte metabolism.
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Affiliation(s)
- Asad Mian
- Dept of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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9
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Abstract
Long-term correction of urea cycle disorders is achieved by correction of the enzymatic defect in hepatocytes. Currently, orthotopic liver transplantation is the primary means of achieving this correction. In the United States most liver transplantations for urea cycle disorders have been restricted to patients with ornithine transcarbamylase deficiency and argininosuccinic aciduria. However, patients with citrullinemia have also received transplants, but more so in Europe and Japan. Recent advances in organ procurement, surgical technique, and immunosuppression have significantly decreased morbidity and mortality. However, unique short-term complications associated with surgery and long-term complications associated with chronic immunosuppression have spurred continued efforts to develop gene replacement therapies for management of acute metabolic decompensations as intercurrent therapy until liver transplantation, and ultimately, for long-term correction. The pathophysiology of urea cycle disorders requires gene vector delivery systems that are highly efficient for liver transduction and transgene expression. To date, adenoviral vectors are unique in fulfilling these criteria, and significant data have been gained in both animal and human studies with early versions of adenoviral vectors. Ultimately, the development of helper-dependent adenoviral vectors may offer the long-term expression and increased margin of safety necessary for adjunctive therapies.
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Affiliation(s)
- B Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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10
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Abstract
Deficiency of any of the five enzymes in the urea cycle results in the accumulation of ammonia and leads to encephalopathy. Episodes of encephalopathy and associated symptoms are unpredictable and, if untreated, are lethal or produce devastating neurologic sequelae in long-term survivors. Although these disorders do not produce liver disease, the consequences of hyperammonemia resemble those seen in patients with hepatic failure or in a transient interference with the urea cycle, as seen in some forms of organic acidemias. Therefore, investigation for hyperammonemia in any infant or child with altered mental status (in the absence of obvious causes, such as trauma, infection, or poisoning) is essential for prompt diagnosis of urea cycle disorders and institution of treatment to avoid brain damage and death. This article addresses the function of the urea cycle and the diagnosis and management of urea cycle disorders.
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Affiliation(s)
- B K Burton
- Division of Genetics, Department of Pediatrics, Northwestern University Medical School, Chicago, Illinois, USA
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11
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Butterworth RF. Evidence for forebrain cholinergic neuronal loss in congenital ornithine transcarbamylase deficiency. Metab Brain Dis 2000; 15:83-91. [PMID: 10885542 DOI: 10.1007/bf02680015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Congenital ornithine transcarbamylase (OTC) deficiency in humans results in failure to thrive, hypotonia, seizures and mental retardation. Neuropathologic evaluation reveals significant cerebral cortical atrophy, delayed myelination and Alzheimer type II astrocytosis. Using an animal model of congenital OTC deficiency, the sparse fur (spf) mouse, studies reveal convincing evidence of a loss of forebrain cholinergic neurons in this condition. Evidence includes (i) reduced activities of the cholinergic nerve terminal enzyme choline acetyltransferase (ChAT), (ii) a 25% loss of ChAT immunostaining, (iii) reduced high affinity transport of [3H]choline by cortical synaptosomes and (iv) a selective reduction in densities of presynaptic muscarinic M2 binding sites, in spf mouse brain compared to controls. A partial correction of the cholinergic deficit was observed following treatment with acetyl-L-carnitine. Possible mechanisms responsible for cholinergic neuronal loss in congenital OTC deficiency include decreased synthesis of the ChAT substrate acetyl CoA, impaired cerebral energy metabolism and NMDA receptor-mediated excitotoxicity. Loss of forebrain cholinergic neurons is consistent with the severe cognitive impairment characteristic of congenital OTC deficiency.
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Affiliation(s)
- R F Butterworth
- Neuroscience Research Unit, CHUM/Hôpital Saint-Luc, Montreal, Quebec, Canada.
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