The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform

L R Ranganath - One of the best experts on this subject based on the ideXlab platform.

Andrew T. Hughes - One of the best experts on this subject based on the ideXlab platform.

  • alkaptonuria many questions answered further challenges beckon
    Annals of Clinical Biochemistry, 2020
    Co-Authors: Andrew S Davison, Andrew T. Hughes, Anna M. Milan, J A Gallagher, Nicolas Sireau, L R Ranganath
    Abstract:

    Alkaptonuria is an iconic rare inherited inborn error of metabolism affecting the tyrosine metabolic pathway, resulting in the accumulation of Homogentisic Acid in the circulation, and significant ...

  • Homogentisic Acid is not only eliminated by glomerular filtration and tubular secretion but also produced in the kidney in alkaptonuria
    Journal of Inherited Metabolic Disease, 2020
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Anna M. Milan, Milad Khedr, Lakshminarayan R Ranganath, Ella Shweihdi
    Abstract:

    The clinical effects of alkaptonuria (AKU) are delayed and ageing influences disease progression. Morbidity of AKU is secondary to high circulating Homogentisic Acid (HGA) and ochronosis. It is not known whether HGA is produced by or processed in the kidney in AKU. Data from AKU patients from four studies were merged to form a single AKU group. A control group of non-AKU subjects was generated by merging data from two non-AKU studies. Data were used to derive renal clearance and fractional excretion (FE) ratios for creatinine, HGA, phenylalanine (PHE) and tyrosine (TYR) using standard calculations, for comparison between the AKU and the control groups. There were 225 AKU patients in the AKU group and 52 in the non-AKU control group. Circulating HGA increased with age (P < 0.001), and was significantly associated with decreased HGA clearance (CLHGA ) (P < 0.001) and FEHGA (P < 0.001). CLHGA and FEHGA were increased beyond the theoretical maximum renal plasma flow, confirming renal production and emphasising the greater contribution of net tubular secretion than glomerular filtration to renal elimination of HGA. The kidneys are crucial to elimination of HGA. Elimination of HGA is impaired with age resulting in worsening disease over time. The kidney is an important site for production of HGA. Tubular secretion of HGA contributes more to elimination of HGA in AKU than glomerular filtration.

  • evaluation of the mitra microsampling device for use with key urinary metabolites in patients with alkaptonuria
    Bioanalysis, 2018
    Co-Authors: Joseph M Taylor, Andrew T. Hughes, Andrew S Davison, Anna M. Milan, L R Ranganath, James Rudge
    Abstract:

    Aim: Alkaptonuria is a disorder of tyrosine metabolism where elevated circulating Homogentisic Acid causes progressive dysfunction of collagenous tissues. Logistical, financial and patient experien...

  • the effect of nitisinone on Homogentisic Acid and tyrosine a two year survey of patients attending the national alkaptonuria centre liverpool
    Annals of Clinical Biochemistry, 2017
    Co-Authors: Anna M. Milan, Andrew T. Hughes, Andrew S Davison, J A Gallagher, Jean Devine, J Usher, Sarah Curtis, Milad Khedr, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare, debilitating autosomal recessive disorder affecting tyrosine metabolism. Deficiency of homogentisate 1,2-dioxygenase leads to increased Homogentisic Acid which is ...

  • serum markers in alkaptonuria simultaneous analysis of Homogentisic Acid tyrosine and nitisinone by liquid chromatography tandem mass spectrometry
    Annals of Clinical Biochemistry, 2015
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Gordon Ross, Anna M. Milan, J A Gallagher, Peter Christensen, John Dutton, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare debilitating autosomal recessive disorder of tyrosine metabolism, where deficiency of homogentisate 1,2-dioxygenase results in increased Homogentisic Acid. Homogentisic Acid is deposited as an ochronotic pigment in connective tissues, especially cartilage, leading to a severe early onset form of osteoarthritis, increased renal and prostatic stone formation and hardening of heart vessels. Treatment with the orphan drug, nitisinone, an inhibitor of 4-hydroxyphenylpyruvate dioxygenase has been shown to reduce urinary excretion of Homogentisic Acid.MethodA reverse phase liquid chromatography tandem mass spectrometry method has been developed to simultaneously analyse serum Homogentisic Acid, tyrosine and nitisinone. Using matrix-matched calibration standards, two product ion transitions were identified for each compound (Homogentisic Acid, tyrosine, nitisinone) and their respective isotopically labelled internal standards (13C6-Homogentisic Acid, d2-tyrosine, 13C6-nitisinone)....

Anna M. Milan - One of the best experts on this subject based on the ideXlab platform.

  • alkaptonuria many questions answered further challenges beckon
    Annals of Clinical Biochemistry, 2020
    Co-Authors: Andrew S Davison, Andrew T. Hughes, Anna M. Milan, J A Gallagher, Nicolas Sireau, L R Ranganath
    Abstract:

    Alkaptonuria is an iconic rare inherited inborn error of metabolism affecting the tyrosine metabolic pathway, resulting in the accumulation of Homogentisic Acid in the circulation, and significant ...

  • Homogentisic Acid is not only eliminated by glomerular filtration and tubular secretion but also produced in the kidney in alkaptonuria
    Journal of Inherited Metabolic Disease, 2020
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Anna M. Milan, Milad Khedr, Lakshminarayan R Ranganath, Ella Shweihdi
    Abstract:

    The clinical effects of alkaptonuria (AKU) are delayed and ageing influences disease progression. Morbidity of AKU is secondary to high circulating Homogentisic Acid (HGA) and ochronosis. It is not known whether HGA is produced by or processed in the kidney in AKU. Data from AKU patients from four studies were merged to form a single AKU group. A control group of non-AKU subjects was generated by merging data from two non-AKU studies. Data were used to derive renal clearance and fractional excretion (FE) ratios for creatinine, HGA, phenylalanine (PHE) and tyrosine (TYR) using standard calculations, for comparison between the AKU and the control groups. There were 225 AKU patients in the AKU group and 52 in the non-AKU control group. Circulating HGA increased with age (P < 0.001), and was significantly associated with decreased HGA clearance (CLHGA ) (P < 0.001) and FEHGA (P < 0.001). CLHGA and FEHGA were increased beyond the theoretical maximum renal plasma flow, confirming renal production and emphasising the greater contribution of net tubular secretion than glomerular filtration to renal elimination of HGA. The kidneys are crucial to elimination of HGA. Elimination of HGA is impaired with age resulting in worsening disease over time. The kidney is an important site for production of HGA. Tubular secretion of HGA contributes more to elimination of HGA in AKU than glomerular filtration.

  • evaluation of the mitra microsampling device for use with key urinary metabolites in patients with alkaptonuria
    Bioanalysis, 2018
    Co-Authors: Joseph M Taylor, Andrew T. Hughes, Andrew S Davison, Anna M. Milan, L R Ranganath, James Rudge
    Abstract:

    Aim: Alkaptonuria is a disorder of tyrosine metabolism where elevated circulating Homogentisic Acid causes progressive dysfunction of collagenous tissues. Logistical, financial and patient experien...

  • the effect of nitisinone on Homogentisic Acid and tyrosine a two year survey of patients attending the national alkaptonuria centre liverpool
    Annals of Clinical Biochemistry, 2017
    Co-Authors: Anna M. Milan, Andrew T. Hughes, Andrew S Davison, J A Gallagher, Jean Devine, J Usher, Sarah Curtis, Milad Khedr, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare, debilitating autosomal recessive disorder affecting tyrosine metabolism. Deficiency of homogentisate 1,2-dioxygenase leads to increased Homogentisic Acid which is ...

  • serum markers in alkaptonuria simultaneous analysis of Homogentisic Acid tyrosine and nitisinone by liquid chromatography tandem mass spectrometry
    Annals of Clinical Biochemistry, 2015
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Gordon Ross, Anna M. Milan, J A Gallagher, Peter Christensen, John Dutton, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare debilitating autosomal recessive disorder of tyrosine metabolism, where deficiency of homogentisate 1,2-dioxygenase results in increased Homogentisic Acid. Homogentisic Acid is deposited as an ochronotic pigment in connective tissues, especially cartilage, leading to a severe early onset form of osteoarthritis, increased renal and prostatic stone formation and hardening of heart vessels. Treatment with the orphan drug, nitisinone, an inhibitor of 4-hydroxyphenylpyruvate dioxygenase has been shown to reduce urinary excretion of Homogentisic Acid.MethodA reverse phase liquid chromatography tandem mass spectrometry method has been developed to simultaneously analyse serum Homogentisic Acid, tyrosine and nitisinone. Using matrix-matched calibration standards, two product ion transitions were identified for each compound (Homogentisic Acid, tyrosine, nitisinone) and their respective isotopically labelled internal standards (13C6-Homogentisic Acid, d2-tyrosine, 13C6-nitisinone)....

J A Gallagher - One of the best experts on this subject based on the ideXlab platform.

  • alkaptonuria many questions answered further challenges beckon
    Annals of Clinical Biochemistry, 2020
    Co-Authors: Andrew S Davison, Andrew T. Hughes, Anna M. Milan, J A Gallagher, Nicolas Sireau, L R Ranganath
    Abstract:

    Alkaptonuria is an iconic rare inherited inborn error of metabolism affecting the tyrosine metabolic pathway, resulting in the accumulation of Homogentisic Acid in the circulation, and significant ...

  • ochronotic pigmentation is caused by Homogentisic Acid and is the key event in alkaptonuria leading to the destructive consequences of the disease a review
    Journal of Inherited Metabolic Disease, 2019
    Co-Authors: Brendan P Norman, L R Ranganath, J A Gallagher
    Abstract:

    Ochronosis is the process in alkaptonuria (AKU) that causes all the debilitating morbidity. The process involves selective deposition of Homogentisic Acid (HGA)-derived pigment in tissues altering the properties of these tissues, leading to their failure. Some tissues like cartilage are more easily affected by ochronosis while others such as the liver and brain are unaffected for reasons that are still not understood. In vitro and mouse models of ochronosis have confirmed the dose relationships between HGA and ochronosis and also their modulation by p-hydroxyphenylpyruvate dioxygenase inhibition. Ochronosis cannot be fully reversed and is a key factor in influencing treatment decisions. Earlier detection of ochronosis preferably by noninvasive means is desirable. A cause-effect relationship between HGA and ochronosis is discussed. The similarity in AKU and familial hypercholesterolaemia is explored and lessons learnt. More research is needed to more fully understand the crucial nature of ochronosis.

  • the effect of nitisinone on Homogentisic Acid and tyrosine a two year survey of patients attending the national alkaptonuria centre liverpool
    Annals of Clinical Biochemistry, 2017
    Co-Authors: Anna M. Milan, Andrew T. Hughes, Andrew S Davison, J A Gallagher, Jean Devine, J Usher, Sarah Curtis, Milad Khedr, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare, debilitating autosomal recessive disorder affecting tyrosine metabolism. Deficiency of homogentisate 1,2-dioxygenase leads to increased Homogentisic Acid which is ...

  • serum markers in alkaptonuria simultaneous analysis of Homogentisic Acid tyrosine and nitisinone by liquid chromatography tandem mass spectrometry
    Annals of Clinical Biochemistry, 2015
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Gordon Ross, Anna M. Milan, J A Gallagher, Peter Christensen, John Dutton, L R Ranganath
    Abstract:

    BackgroundAlkaptonuria is a rare debilitating autosomal recessive disorder of tyrosine metabolism, where deficiency of homogentisate 1,2-dioxygenase results in increased Homogentisic Acid. Homogentisic Acid is deposited as an ochronotic pigment in connective tissues, especially cartilage, leading to a severe early onset form of osteoarthritis, increased renal and prostatic stone formation and hardening of heart vessels. Treatment with the orphan drug, nitisinone, an inhibitor of 4-hydroxyphenylpyruvate dioxygenase has been shown to reduce urinary excretion of Homogentisic Acid.MethodA reverse phase liquid chromatography tandem mass spectrometry method has been developed to simultaneously analyse serum Homogentisic Acid, tyrosine and nitisinone. Using matrix-matched calibration standards, two product ion transitions were identified for each compound (Homogentisic Acid, tyrosine, nitisinone) and their respective isotopically labelled internal standards (13C6-Homogentisic Acid, d2-tyrosine, 13C6-nitisinone)....

  • urine Homogentisic Acid and tyrosine simultaneous analysis by liquid chromatography tandem mass spectrometry
    Journal of Chromatography B, 2014
    Co-Authors: Andrew T. Hughes, Andrew S Davison, Gordon Ross, Anna M. Milan, J A Gallagher, Peter Christensen, John Dutton, L R Ranganath
    Abstract:

    Alkaptonuria (AKU) is a rare debilitating autosomal recessive disorder of tyrosine metabolism. Deficiency of homogentisate 1,2-dioxygenase results in increased Homogentisic Acid (HGA) which although excreted in gram quantities in the urine, is deposited as an ochronotic pigment in connective tissues, especially cartilage. Ochronosis leads to a severe, early-onset form of osteoarthritis, increased renal and prostatic stone formation and hardening of heart vessels. Treatment with the orphan drug, Nitisinone, an inhibitor of the enzyme 4-hydroxyphenylpyruvate dioxygenase has been shown to reduce urinary excretion of HGA, resulting in accumulation of the upstream pre-cursor, tyrosine. Using reverse phase LC-MS/MS, a method has been developed to simultaneously quantify urinary HGA and tyrosine. Using matrix-matched calibration standards, two product ion transitions were identified for each compound and their appropriate isotopically labelled internal standards. Validation was performed across the AKU and post-treatment concentrations expected. Intrabatch accuracy for Acidified urine was 96-109% for tyrosine and 94-107% for HGA; interbatch accuracy (n=20 across ten assays) was 95-110% for tyrosine and 91-109% for HGA. Precision, both intra- and interbatch was <10% for tyrosine and <5% for HGA. Matrix effects observed with Acidified urine (12% decrease, CV 5.6%) were normalised by the internal standard. Tyrosine and HGA were proved stable under various storage conditions and no carryover, was observed. Overall the method developed and validated shows good precision, accuracy and linearity appropriate for the monitoring of patients with AKU, pre and post-nitisinone therapy.

Annalisa Santucci - One of the best experts on this subject based on the ideXlab platform.

  • Homogentisic Acid affects human osteoblastic functionality by oxidative stress and alteration of the wnt β catenin signaling pathway
    Journal of Cellular Physiology, 2020
    Co-Authors: Maria Lucia Schiavone, Giulia Bernardini, Lia Millucci, Barbara Marzocchi, Daniela Giustarini, Ranieri Rossi, Annalisa Santucci
    Abstract:

    Alkaptonuria (AKU) is a rare disease correlated with deficiency of the enzyme homogentisate 1,2 dioxygenase, which causes Homogentisic Acid (HGA) accumulation. HGA is subjected to oxidation/polymerization reactions, leading to the production of a peculiar melanin-like pigmentation (ochronosis) after chronic inflammation, which is considered as a triggering event for the generation of oxidative stress. Clinical manifestations of AKU are urine darkening, sclera pigmentation, early severe osteoarthropathy, and cardiovascular and renal complication. Despite major clinical manifestations of AKU being observed in the bones and skeleton, the molecular and functional parameters are so far unknown in AKU. In the present study, we used human osteoblasts supplemented with HGA as a AKU cellular model. We observed marked oxidative stress, and for the first time, we were able to correlate HGA deposition with an impairment in the Wnt/β-catenin signaling pathway, opening a range of possible therapeutic strategies for a disease still lacking a known cure.

  • quick diagnosis of alkaptonuria by Homogentisic Acid determination in urine paper spots
    JIMD reports, 2016
    Co-Authors: Gabriella Jacomelli, Lia Millucci, Giulia Bernardini, Vanna Micheli, Annalisa Santucci
    Abstract:

    Objectives: Two methods are described for Homogentisic Acid (HGA) determination in dried urine spots (DUS) on paper from Alkaptonuria (AKU) patients, devised for quick early diagnosis. AKU is a rare autosomal recessive disorder caused by deficiency of homogentisate 1,2-dioxygenase, yielding in accumulation of HGA. Its massive excretion causes urine darkening by exposure to air or alkalinization, and is a diagnostic marker. The deposition of polymers produced after HGA oxidation within the connective tissues causes ochronotic arthritis, a degenerative joint disease manifesting in adulthood and only rarely in childhood. No early diagnosis is usually accomplished, awareness following symptom development.

  • inhibition of para hydroxyphenylpyruvate dioxygenase by analogues of the herbicide nitisinone as a strategy to decrease Homogentisic Acid levels the causative agent of alkaptonuria
    ChemMedChem, 2016
    Co-Authors: Marcella Laschi, Giulia Bernardini, Daniela Braconi, Fabrizio Manetti, Elena Dreassi, Lia Millucci, Michela Geminiani, Barbara Marzocchi, Maurizio Botta, Annalisa Santucci
    Abstract:

    Alkaptonuria (AKU) is a rare multisystem metabolic disease caused by deficient activity of homogentisate 1,2-dioxygenase (HGD), which leads to the accumulation of Homogentisic Acid (HGA). Currently, there is no treatment for AKU. The sole drug with some beneficial effects is the herbicide nitisinone (1), an inhibitor of p-hydroxyphenylpyruvate dioxygenase (4-HPPD). 1 has been used as a life-saving drug in infants with type I tyrosinemia despite severe side effects due to the buildup of tyrosine. Four clinical trials of nitisinone to treat AKU have shown that 1 consistently decreases HGA levels, but also caused the accumulation of tyrosine in blood serum. Moreover, the human preclinical toxicological data for 1 are incomplete. In this work, we performed pharmacodynamics and toxicological evaluations of 1, providing the first report of LD50 values in human cells. Intracellular tyrosinemia was also evaluated. Three additional 4-HPPD inhibitors with a more favorable profile than that of 1 in terms of IC50, LD50, and tyrosine accumulation were also identified among commercially available compounds. These may be promising starting points for the development of new therapeutic strategies for the treatment of AKU.

  • Redox-proteomics of the effects of Homogentisic Acid in an in vitro human serum model of alkaptonuric ochronosis
    Journal of Inherited Metabolic Disease, 2011
    Co-Authors: Daniela Braconi, Giulia Bernardini, Marcella Laschi, Lia Millucci, Adriano Spreafico, Claretta Bianchini, Annalisa Santucci
    Abstract:

    Alkaptonuria (AKU) is a rare inborn error of metabolism associated with a deficient activity of homogentisate 1,2-dioxygenase (HGO), an enzyme involved in tyrosine and phenylalanine metabolism. Such a deficiency leads to the accumulation of Homogentisic Acid (HGA) and its oxidized/polymerized products in connective tissues, where melanin-like pigments accumulate (ochronosis). Ochronosis involves especially joints, where an ochronotic arthropathy develops. Little is known on the molecular mechanisms leading to ochronosis and ochronotic arthropathy in AKU. Previous works of ours showed that HGA in vitro propagates oxidative stress through its conversion into benzoquinone acetate (BQA). We hence used an in vitro model consisting of human serum treated with HGA and evaluated the activities of glutathione related anti-oxidant enzymes and levels of compounds indexes of oxidative stress. Proteomics and redox-proteomics were used to identify oxidized proteins and proteins more likely able to bind BQA. Overall, we found that the production of ochronotic pigment in HGA-treated serum is accompanied by lipid peroxidation, decreased activity of the enzyme glutathione peroxidase and massive depletion of thiol groups, together with increased protein carbonylation and thiol oxidation. We also found that BQA was likely to bind carrier proteins and naturally abundant serum proteins, eventually altering their chemico-physical properties. Concluding, our work points towards a critical importance of thiol compounds in counteracting HGA- and BQA- mediated stress in AKU, so that future research for disease biomarkers and pharmacological treatments for AKU and ochronosis will be more easily addressed.

  • proteomic and redox proteomic evaluation of Homogentisic Acid and ascorbic Acid effects on human articular chondrocytes
    Journal of Cellular Biochemistry, 2010
    Co-Authors: Daniela Braconi, Giulia Bernardini, J A Gallagher, Marcella Laschi, Laura Tinti, Adam Michael Taylor, Adriano Spreafico, Annalisa Santucci
    Abstract:

    Alkaptonuria (AKU) is a rare genetic disease associated with the accumulation of Homogentisic Acid (HGA) and its oxidized/polymerized products in connective tissues up to the deposition of melanin-like pigments (ochronosis). Since little is known on the effects of HGA and its metabolites on articular cells, we carried out a proteomic and redox-proteomic analysis to investigate how HGA and ascorbic Acid (ASC) affect the human chondrocytic protein repertoire. We settled up an in vitro model using a human chondrocytic cell line to evaluate the effects of 0.33 mM HGA, alone or combined with ASC. We found that HGA and ASC significantly affect the levels of proteins with specific functions in protein folding, cell organization and, notably, stress response and cell defense. Increased protein carbonyls levels were found either in HGA or ASC treated cells, and evidences produced in this paper support the hypothesis that HGA-induced stress might be mediated by protein oxidation. Our finding can lay the basis towards the settling up of more sophisticated models to study AKU and ochronosis.