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Gochman A, Do TQ, Kim K, Schwarz JA, Thorpe MP, Blackwell DJ, Ritschel PA, Smith AN, Rebbeck RT, Akers WS, Cornea RL, Laver DR, Johnston JN, Knollmann BC. ent-Verticilide B1 Inhibits Type 2 Ryanodine Receptor Channels and is Antiarrhythmic in Casq2 -/- Mice. Mol Pharmacol 2024; 105:194-201. [PMID: 38253398 PMCID: PMC10877729 DOI: 10.1124/molpharm.123.000752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 12/20/2023] [Accepted: 01/02/2024] [Indexed: 01/24/2024] Open
Abstract
Intracellular Ca2+ leak from cardiac ryanodine receptor (RyR2) is an established mechanism of sudden cardiac death (SCD), whereby dysregulated Ca2+ handling causes ventricular arrhythmias. We previously discovered the RyR2-selective inhibitor ent-(+)-verticilide (ent-1), a 24-membered cyclooligomeric depsipeptide that is the enantiomeric form of a natural product (nat-(-)-verticilide). Here, we examined its 18-membered ring-size oligomer (ent-verticilide B1; "ent-B1") in RyR2 single channel and [3H]ryanodine binding assays, and in Casq2 -/- cardiomyocytes and mice, a gene-targeted model of SCD. ent-B1 inhibited RyR2 single channels and RyR2-mediated spontaneous Ca2+ release in Casq2 -/- cardiomyocytes with sub-micromolar potency. ent-B1 was a partial RyR2 inhibitor, with maximal inhibitory efficacy of less than 50%. ent-B1 was stable in plasma, with a peak plasma concentration of 1460 ng/ml at 10 minutes and half-life of 45 minutes after intraperitoneal administration of 3 mg/kg in mice. In vivo, ent-B1 significantly reduced catecholamine-induced ventricular arrhythmias in Casq2 -/- mice in a dose-dependent manner. Hence, we have identified a novel chemical entity - ent-B1 - that preserves the mechanism of action of a hit compound and shows therapeutic efficacy. These findings strengthen RyR2 as an antiarrhythmic drug target and highlight the potential of investigating the mirror-image isomers of natural products to discover new therapeutics. SIGNIFICANCE STATEMENT: The cardiac ryanodine receptor (RyR2) is an untapped target in the stagnant field of antiarrhythmic drug development. We have confirmed RyR2 as an antiarrhythmic target in a mouse model of sudden cardiac death and shown the therapeutic efficacy of a second enantiomeric natural product.
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Affiliation(s)
- Aaron Gochman
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Tri Q Do
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Kyungsoo Kim
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Jacob A Schwarz
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Madelaine P Thorpe
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Paxton A Ritschel
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Abigail N Smith
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Robyn T Rebbeck
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Wendell S Akers
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Razvan L Cornea
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Derek R Laver
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Jeffrey N Johnston
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
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Šeflová J, Schwarz JA, Smith AN, Svensson B, Blackwell DJ, Phillips TA, Nikolaienko R, Bovo E, Rebbeck RT, Zima AV, Thomas DD, Van Petegem F, Knollmann BC, Johnston JN, Robia SL, Cornea RL. RyR2 Binding of an Antiarrhythmic Cyclic Depsipeptide Mapped Using Confocal Fluorescence Lifetime Detection of FRET. ACS Chem Biol 2023; 18:2290-2299. [PMID: 37769131 DOI: 10.1021/acschembio.3c00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Hyperactivity of cardiac sarcoplasmic reticulum (SR) ryanodine receptor (RyR2) Ca2+-release channels contributes to heart failure and arrhythmias. Reducing the RyR2 activity, particularly during cardiac relaxation (diastole), is a desirable therapeutic goal. We previously reported that the unnatural enantiomer (ent) of an insect-RyR activator, verticilide, inhibits porcine and mouse RyR2 at diastolic (nanomolar) Ca2+ and has in vivo efficacy against atrial and ventricular arrhythmia. To determine the ent-verticilide structural mode of action on RyR2 and guide its further development via medicinal chemistry structure-activity relationship studies, here, we used fluorescence lifetime (FLT)-measurements of Förster resonance energy transfer (FRET) in HEK293 cells expressing human RyR2. For these studies, we used an RyR-specific FRET molecular-toolkit and computational methods for trilateration (i.e., using distances to locate a point of interest). Multiexponential analysis of FLT-FRET measurements between four donor-labeled FKBP12.6 variants and acceptor-labeled ent-verticilide yielded distance relationships placing the acceptor probe at two candidate loci within the RyR2 cryo-EM map. One locus is within the Ry12 domain (at the corner periphery of the RyR2 tetrameric complex). The other locus is sandwiched at the interface between helical domain 1 and the SPRY3 domain. These findings document RyR2-target engagement by ent-verticilide, reveal new insight into the mechanism of action of this new class of RyR2-targeting drug candidate, and can serve as input in future computational determinations of the ent-verticilide binding site on RyR2 that will inform structure-activity studies for lead optimization.
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Affiliation(s)
- Jaroslava Šeflová
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Jacob A Schwarz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Abigail N Smith
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Taylor A Phillips
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Björn C Knollmann
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Răzvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Gochman A, Do TQ, Kim K, Schwarz JA, Thorpe MP, Blackwell DJ, Smith AN, Akers WS, Cornea RL, Laver DR, Johnston JN, Knollmann BC. ent -Verticilide B1 inhibits type 2 ryanodine receptor channels and is antiarrhythmic in Casq2-/- mice. bioRxiv 2023:2023.07.03.547578. [PMID: 37461611 PMCID: PMC10349981 DOI: 10.1101/2023.07.03.547578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Ca 2+ leak from cardiac ryanodine receptor (RyR2) is an established mechanism of sudden cardiac death (SCD), whereby dysregulated Ca 2+ handling causes ventricular arrhythmias. We previously discovered the RyR2-selective inhibitor ent- (+)-verticilide ( ent -1), a 24-membered cyclooligomeric depsipeptide that is the enantiomeric form of a natural product ( nat -(-)-verticilide). Here, we examined its 18-membered ring-size oligomer ( ent -verticilide B1; " ent -B1") in single RyR2 channel assays, [ 3 H]ryanodine binding assays, and in Casq2 -/- cardiomyocytes and mice, a gene-targeted model of SCD. ent -B1 inhibited RyR2 single-channels and [ 3 H]ryanodine binding with low micromolar potency, and RyR2-mediated spontaneous Ca 2+ release in Casq2-/- cardiomyocytes with sub-micromolar potency. ent -B1 was a partial RyR2 inhibitor, with maximal inhibitory efficacy of less than 50%. ent -B1 was stable in plasma, with a peak plasma concentration of 1460 ng/ml at 10 min and half-life of 45 min after intraperitoneal administration of 3 mg/kg in mice. Both 3 mg/kg and 30 mg/kg ent -B1 significantly reduced catecholamine-induced ventricular arrhythmia in Casq2-/- mice. Hence, we have identified a novel chemical entity - ent -B1 - that preserves the mechanism of action of a hit compound and shows therapeutic efficacy. These findings strengthen RyR2 as an antiarrhythmic drug target and highlight the potential of investigating the mirror-image isomers of natural products to discover new therapeutics. Significance statement The cardiac ryanodine receptor (RyR2) is an untapped target in the stagnant field of antiarrhythmic drug development. We have confirmed RyR2 as an antiarrhythmic target in a mouse model of sudden cardiac death and shown the therapeutic efficacy of a second enantiomeric natural product.
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Blackwell DJ, Smith AN, Do T, Gochman A, Schmeckpeper J, Hopkins CR, Akers WS, Johnston JN, Knollmann BC. In Vivo Pharmacokinetic and Pharmacodynamic Properties of the Antiarrhythmic Molecule ent-Verticilide. J Pharmacol Exp Ther 2023; 385:205-213. [PMID: 36894328 PMCID: PMC10201578 DOI: 10.1124/jpet.122.001455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/19/2023] [Accepted: 02/24/2023] [Indexed: 03/11/2023] Open
Abstract
The unnatural verticilide enantiomer (ent-verticilide) is a selective and potent inhibitor of cardiac ryanodine receptor (RyR2) calcium release channels and exhibits antiarrhythmic activity in a murine model of catecholaminergic polymorphic ventricular tachycardia (CPVT). To determine verticilide's pharmacokinetic and pharmacodynamic properties in vivo, we developed a bioassay to measure nat- and ent-verticilide in murine plasma and correlated plasma concentrations with antiarrhythmic efficacy in a mouse model of CPVT. nat-Verticilide rapidly degraded in plasma in vitro, showing >95% degradation within 5 minutes, whereas ent-verticilide showed <1% degradation over 6 hours. Plasma was collected from mice following intraperitoneal administration of ent-verticilide at two doses (3 mg/kg, 30 mg/kg). Peak C max and area under the plasma-concentration time curve (AUC) scaled proportionally to dose, and the half-life was 6.9 hours for the 3-mg/kg dose and 6.4 hours for the 30-mg/kg dose. Antiarrhythmic efficacy was examined using a catecholamine challenge protocol at time points ranging from 5 to 1440 minutes after intraperitoneal dosing. ent-Verticilide inhibited ventricular arrhythmias as early as 7 minutes after administration in a concentration-dependent manner, with an estimated potency (IC50) of 266 ng/ml (312 nM) and an estimated maximum inhibitory effect of 93.5%. Unlike the US Food and Drug Administration-approved pan-RyR blocker dantrolene, the RyR2-selective blocker ent-verticilide (30 mg/kg) did not reduce skeletal muscle strength in vivo. We conclude that ent-verticilide has favorable pharmacokinetic properties and reduces ventricular arrhythmias with an estimated potency in the nanomolar range, warranting further drug development. SIGNIFICANCE STATEMENT: ent-Verticilide has therapeutic potential to treat cardiac arrhythmias, but little is known about its pharmacological profile in vivo. The primary purpose of this study is to determine the systemic exposure and pharmacokinetics of ent-verticilide in mice and estimate its efficacy and potency in vivo. The current work suggests ent-verticilide has favorable pharmacokinetic properties and reduces ventricular arrhythmias with an estimated potency in the nanomolar range, warranting further drug development.
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Affiliation(s)
- Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Abigail N Smith
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Tri Do
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Aaron Gochman
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jeffrey Schmeckpeper
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Corey R Hopkins
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Wendell S Akers
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jeffrey N Johnston
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Bjorn C Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
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van Opbergen CJM, Bagwan N, Maurya SR, Kim JC, Smith AN, Blackwell DJ, Johnston JN, Knollmann BC, Cerrone M, Lundby A, Delmar M. Exercise Causes Arrhythmogenic Remodeling of Intracellular Calcium Dynamics in Plakophilin-2-Deficient Hearts. Circulation 2022; 145:1480-1496. [PMID: 35491884 PMCID: PMC9086182 DOI: 10.1161/circulationaha.121.057757] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Exercise training, and catecholaminergic stimulation, increase the incidence of arrhythmic events in patients affected with arrhythmogenic right ventricular cardiomyopathy correlated with plakophilin-2 (PKP2) mutations. Separate data show that reduced abundance of PKP2 leads to dysregulation of intracellular Ca2+ (Ca2+i) homeostasis. Here, we study the relation between excercise, catecholaminergic stimulation, Ca2+i homeostasis, and arrhythmogenesis in PKP2-deficient murine hearts. METHODS Experiments were performed in myocytes from a cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout murine line (PKP2cKO). For training, mice underwent 75 minutes of treadmill running once per day, 5 days each week for 6 weeks. We used multiple approaches including imaging, high-resolution mass spectrometry, electrocardiography, and pharmacological challenges to study the functional properties of cells/hearts in vitro and in vivo. RESULTS In myocytes from PKP2cKO animals, training increased sarcoplasmic reticulum Ca2+ load, increased the frequency and amplitude of spontaneous ryanodine receptor (ryanodine receptor 2)-mediated Ca2+ release events (sparks), and changed the time course of sarcomeric shortening. Phosphoproteomics analysis revealed that training led to hyperphosphorylation of phospholamban in residues 16 and 17, suggesting a catecholaminergic component. Isoproterenol-induced increase in Ca2+i transient amplitude showed a differential response to β-adrenergic blockade that depended on the purported ability of the blockers to reach intracellular receptors. Additional experiments showed significant reduction of isoproterenol-induced Ca2+i sparks and ventricular arrhythmias in PKP2cKO hearts exposed to an experimental blocker of ryanodine receptor 2 channels. CONCLUSIONS Exercise disproportionately affects Ca2+i homeostasis in PKP2-deficient hearts in a manner facilitated by stimulation of intracellular β-adrenergic receptors and hyperphosphorylation of phospholamban. These cellular changes create a proarrhythmogenic state that can be mitigated by ryanodine receptor 2 blockade. Our data unveil an arrhythmogenic mechanism for exercise-induced or catecholaminergic life-threatening arrhythmias in the setting of PKP2 deficit. We suggest that membrane-permeable β-blockers are potentially more efficient for patients with arrhythmogenic right ventricular cardiomyopathy, highlight the potential for ryanodine receptor 2 channel blockers as treatment for the control of heart rhythm in the population at risk, and propose that PKP2-dependent and phospholamban-dependent arrhythmogenic right ventricular cardiomyopathy-related arrhythmias have a common mechanism.
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Affiliation(s)
- Chantal JM van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Navratan Bagwan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Svetlana R Maurya
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joon-Chul Kim
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Abigail N Smith
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey N Johnston
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Marina Cerrone
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Alicia Lundby
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
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6
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Thorpe MP, Smith AN, Crocker MS, Johnston JN. Resolving Bromonitromethane Sourcing by Synthesis: Preparation at the Decagram Scale. J Org Chem 2022; 87:5451-5455. [PMID: 35364809 PMCID: PMC9109156 DOI: 10.1021/acs.joc.2c00405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The accessibility of bromonitromethane has declined in recent years, limiting its viability as a reagent for chemical synthesis. The reinvestigation and optimization of a variety of preparations, and the development of safe operating principles, are described. The reproducible protocol described here leverages the effectiveness of hydroxide for nitromethane bromination while respecting its incompatibility with the product it forms. This careful balance was achieved at scales up to 56 g, resulting in a reproducible procedure that provides straightforward, sustainable, and affordable access to this critical reagent.
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Affiliation(s)
- Madelaine P Thorpe
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Abigail N Smith
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Michael S Crocker
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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7
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Schwarz JA, Blackwell D, Smith AN, Rebbeck RT, Johnston JN, Knollmann BC, Cornea RL. Insight into the therapeutic potential of ent-verticilide based on direct measures of RyR function. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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8
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Smith AN, Blackwell DJ, Knollmann BC, Johnston JN. Ring Size as an Independent Variable in Cyclooligomeric Depsipeptide Antiarrhythmic Activity. ACS Med Chem Lett 2021; 12:1942-1947. [PMID: 34917258 DOI: 10.1021/acsmedchemlett.1c00508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022] Open
Abstract
Hit-to-lead studies employ a variety of strategies to optimize binding to a target of interest. When a structure for the target is available, hypothesis-driven structure-activity relationships (SAR) are a powerful strategy for refining the pharmacophore to achieve robust binding and selectivity characteristics necessary to identify a lead compound. Recrafting the three-dimensional space occupied by a small molecule, optimization of hydrogen bond contacts, and enhancing local attractive interactions are traditional approaches in medicinal chemistry. Ring size, however, is rarely able to be leveraged as an independent variable because most hits lack the symmetry required for such a study. Our discovery that the cyclic oligomeric depsipeptide ent-verticilide inhibits mammalian cardiac ryanodine receptor calcium release channels with submicromolar potency provided an opportunity to explore ring size as a variable, independent of other structural or functional group changes. We report here that ring size can be a critical independent variable, suggesting that modest conformational changes alone can dramatically affect potency.
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Affiliation(s)
- Abigail N. Smith
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Daniel J. Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Bjorn C. Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Jeffrey N. Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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9
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Smith AN, Johnston JN. The Formation of Impossible Rings in Macrocyclooligomerizations for Cyclodepsipeptide Synthesis: The 18-from-12 Paradox. J Org Chem 2021; 86:7904-7919. [PMID: 34097410 DOI: 10.1021/acs.joc.0c03069] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A reinvestigation into the macrocyclooligomerization (MCO) of a tetradepsipeptide is reported, uncovering a paradox in which the MCO of depsipeptide monomers can produce "impossible" ring sizes: a 12-atom chain produced the expected 24-membered ring, alongside unexpected 18- and 30-membered cyclic oligomeric depsipeptides (CODs). We report an alternative preparation of authentic 18- and 36-membered macrocycles for this case using a stepwise synthesis that provides definitive analytical characterization for each ring size. Our investigation yields a recharacterization and reassignment of two macrocycles originally reported in this MCO series, along with updated yields and isothermal titration calorimetry data after implementation of new critical protocols for purification and subsequent analysis. Initial studies to probe this mechanistic conundrum are described.
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Affiliation(s)
- Abigail N Smith
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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10
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Abstract
RATIONALE The class Ic antiarrhythmic drug flecainide prevents ventricular tachyarrhythmia in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), a disease caused by hyperactive RyR2 (cardiac ryanodine receptor) mediated calcium (Ca) release. Although flecainide inhibits single RyR2 channels in vitro, reports have claimed that RyR2 inhibition by flecainide is not relevant for its mechanism of antiarrhythmic action and concluded that sodium channel block alone is responsible for flecainide's efficacy in CPVT. OBJECTIVE To determine whether RyR2 block independently contributes to flecainide's efficacy for suppressing spontaneous sarcoplasmic reticulum Ca release and for preventing ventricular tachycardia in vivo. METHODS AND RESULTS We synthesized N-methylated flecainide analogues (QX-flecainide and N-methyl flecainide) and showed that N-methylation reduces flecainide's inhibitory potency on RyR2 channels incorporated into artificial lipid bilayers. N-methylation did not alter flecainide's inhibitory activity on human cardiac sodium channels expressed in HEK293T cells. Antiarrhythmic efficacy was tested utilizing a Casq2 (cardiac calsequestrin) knockout (Casq2-/-) CPVT mouse model. In membrane-permeabilized Casq2-/- cardiomyocytes-lacking intact sarcolemma and devoid of sodium channel contribution-flecainide, but not its analogues, suppressed RyR2-mediated Ca release at clinically relevant concentrations. In voltage-clamped, intact Casq2-/- cardiomyocytes pretreated with tetrodotoxin to inhibit sodium channels and isolate the effect of flecainide on RyR2, flecainide significantly reduced the frequency of spontaneous sarcoplasmic reticulum Ca release, while QX-flecainide and N-methyl flecainide did not. In vivo, flecainide effectively suppressed catecholamine-induced ventricular tachyarrhythmias in Casq2-/- mice, whereas N-methyl flecainide had no significant effect on arrhythmia burden, despite comparable sodium channel block. CONCLUSIONS Flecainide remains an effective inhibitor of RyR2-mediated arrhythmogenic Ca release even when cardiac sodium channels are blocked. In mice with CPVT, sodium channel block alone did not prevent ventricular tachycardia. Hence, RyR2 channel inhibition likely constitutes the principal mechanism of antiarrhythmic action of flecainide in CPVT.
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Affiliation(s)
- Dmytro O Kryshtal
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Christian L Egly
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Abigail N Smith
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Suzanne M Batiste
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Jeffrey N Johnston
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, Australia (D.R.L.)
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
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11
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Affiliation(s)
- A N Smith
- Department of Clinical Surgery, University of Edinburgh and Gastrointestinal Unit, Western General Hospital, Edinburgh, EH4 2XU
| | - W O Kirwan
- Department of Clinical Surgery, University of Edinburgh and Gastrointestinal Unit, Western General Hospital, Edinburgh, EH4 2XU
| | - S Shariff
- Department of Clinical Surgery, University of Edinburgh and Gastrointestinal Unit, Western General Hospital, Edinburgh, EH4 2XU
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12
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Playford MC, Dawson K, Playford SE, Smith AN, Page SW, Collins K, Forsberg N. Effect of an immunomodulatory feed additive on markers of immunity in pasture-fed dairy cows. Aust Vet J 2015; 92:479-81. [PMID: 25424760 DOI: 10.1111/avj.12269] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Infectious diseases in dairy cows often follow a time of nutritional or physiological stress and the subsequent altered immune system function. This study aimed to determine if the immunomodulatory effects of a feed additive previously observed in experimental animals and housed cattle fed total mixed rations could be reproduced in pasture-fed dairy cattle under Australian conditions. METHODS The study included 34 pasture-fed dairy cattle given the treatment (n = 17) or placebo (bentonite, n = 17) for an acclimation period of 15 days followed by 60 days of supplementation. Blood tests were taken pre-trial and then 30, 60 and 90 days after acclimation. Blood samples were extracted and preserved in Trizol and analysed for immune markers. RESULTS Pasture-fed dairy cows in the treatment group had significantly higher levels of the immune markers interleukin-8R and L-selectin in comparison with placebo-fed cows at 60 days after the start of supplementation. CONCLUSION The immunomodulatory effects of the additive observed in the current study and the associated enhanced neutrophil function demonstrated by other studies suggest a role in decreasing the rates of mastitis and other infectious diseases of dairy cattle, particularly during times of nutritional or physiological stress.
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Affiliation(s)
- M C Playford
- Dawbuts Pty Ltd, PO Box 1118, Camden, New South Wales, 2570, Australia.
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13
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Playford MC, Smith AN, Love S, Besier RB, Kluver P, Bailey JN. Prevalence and severity of anthelmintic resistance in ovine gastrointestinal nematodes in Australia (2009-2012). Aust Vet J 2015; 92:464-71. [PMID: 25424758 DOI: 10.1111/avj.12271] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVE This study aimed to provide an indication of the prevalence and severity of anthelmintic resistance (AR) in the Australian sheep industry by compiling the results of faecal worm egg count reduction tests (FECRTs). METHODS Government and private parasitology laboratories, pharmaceutical companies and veterinarians known to have conducted FECRTs were asked to provide results that conformed to Australian and New Zealand standard diagnostic procedures. RESULTS Data were available from a total of 390 tests, with larval differentiation conducted in 222 cases. Pooled results from all states for the macrocyclic lactone (ML) class showed a lower prevalence of AR against combined species for moxidectin (54%) compared with abamectin (77%) and ivermectin (87%). Analysis by state revealed higher levels of ML-resistant Teladorsagia sp. in Tasmania and Western Australia than in other states and ML-resistant Haemonchus sp. was more frequently detected in New South Wales. CONCLUSION This compilation of results of FECRTs conducted by Australian parasitology laboratories in 2009-12 showed widespread AR of the common sheep nematodes (Teladorsagia, Trichostrongylus and Haemonchus) to all broad-spectrum anthelmintics, with the exception of monepantel, whether used singly or in combination.
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14
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Collette SA, Allstadt SD, Chon EM, Vernau W, Smith AN, Garrett LD, Choy K, Rebhun RB, Rodriguez CO, Skorupski KA. Treatment of feline intermediate- to high-grade lymphoma with a modified university of Wisconsin-Madison protocol: 119 cases (2004-2012). Vet Comp Oncol 2015; 14 Suppl 1:136-46. [PMID: 26109275 DOI: 10.1111/vco.12158] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 05/03/2015] [Accepted: 05/04/2015] [Indexed: 12/31/2022]
Abstract
CHOP-based (cyclophosphamide, doxorubicin, vinca alkaloid, prednisolone) chemotherapy protocols are often recommended for treatment of feline lymphoma. While maintenance-free CHOP-based protocols have been published and readily used in dogs, there is limited literature regarding similar maintenance-free protocols in cats. The purpose of this study was to describe the outcome of cats with intermediate- to high-grade lymphoma that were prescribed a modified 25-week University of Wisconsin-Madison (UW-25) chemotherapy protocol. A secondary objective was examination of potential prognostic factors. One hundred and nineteen cats from five institutions treated with a UW-25-based protocol were included. The Kaplan-Meier median progression-free interval (PFI) and survival time (MST) were 56 and 97 (range 2-2019) days, respectively. Cats assessed as having a complete response (CR) to therapy had significantly longer PFI and MST than those with partial or no response (PFI 205 versus 54 versus 21 days, respectively, P < 0.0001 and MST 318 versus 85 versus 27 days, respectively, P < 0.0001).
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Affiliation(s)
- S A Collette
- Veterinary Medical Teaching Hospital, University of California-Davis, Davis, CA, USA.,Oncology Service, Upstate Veterinary Specialists, Greenville, SC, USA
| | - S D Allstadt
- Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA, USA.,Oncology Service, Blue Pearl Veterinary Partners, Louisville, KY, USA
| | - E M Chon
- Department of Medical Sciences, Univeristy of Wisconsin-Madison, Madison, WI, USA
| | - W Vernau
- Department of Pathology, Microbiology and Immunology, University of California-Davis, CA, USA
| | - A N Smith
- Department of Clinical Sciences, Auburn University, Auburn, AL, USA
| | - L D Garrett
- Department of Veterinary Clinical Medicine, University of Illinois, Urbana, IL, USA
| | - K Choy
- Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA, USA.,Oncology Service, Seattle Veterinary Specialists, Seattle, WA, USA
| | - R B Rebhun
- Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA, USA
| | - C O Rodriguez
- Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA, USA
| | - K A Skorupski
- Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA, USA
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15
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Back AR, Schleis SE, Smrkovski OA, Lee J, Smith AN, Phillips JC. Mechlorethamine, vincristine, melphalan and prednisone (MOMP) for the treatment of relapsed lymphoma in dogs. Vet Comp Oncol 2013; 13:398-408. [PMID: 23910023 DOI: 10.1111/vco.12055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/18/2013] [Accepted: 06/18/2013] [Indexed: 12/20/2022]
Abstract
Eighty-eight dogs with relapsed lymphoma were treated with the MOMP (mechlorethamine, vincristine, melphalan and prednisone) protocol on a 28-day treatment cycle. The overall response rate (ORR) to the MOMP protocol was 51.1% for a median of 56 days (range 7-858 days). Twelve percent of dogs experienced a complete response for a median of 81 days (range 42-274 days) and 38.6% experienced a partial response for a median of 49 days (range 7-858 days). Dogs with T-cell lymphoma had an ORR of 55% for a median of 60 days (range 49-858 days) while those with B-cell lymphoma had an ORR of 57% for a median of 81 days (range 7-274 days) (P = 0.783). The overall survival time for all dogs was 183 days (range 17-974 days). Fifty-four percent of dogs experienced toxicity with the majority classified as grade I. The MOMP protocol seems well-tolerated and is an option for dogs with relapsed lymphoma.
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Affiliation(s)
- A R Back
- Comparative Oncology Program, Department of Clinical Sciences, Auburn University, College of Veterinary Medicine, Auburn, AL, USA
| | - S E Schleis
- Comparative Oncology Program, Department of Clinical Sciences, Auburn University, College of Veterinary Medicine, Auburn, AL, USA
| | - O A Smrkovski
- Comparative Oncology Program, Department of Small Animal Medicine, University of Tennessee, College of Veterinary Medicine, Knoxville, TN, USA
| | - J Lee
- Comparative Oncology Program, Department of Small Animal Medicine, University of Tennessee, College of Veterinary Medicine, Knoxville, TN, USA
| | - A N Smith
- Comparative Oncology Program, Department of Clinical Sciences, Auburn University, College of Veterinary Medicine, Auburn, AL, USA
| | - J C Phillips
- Animal Emergency Critical Care and Referral Center, Knoxville, TN, USA
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16
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Abstract
An intact, 8-year-old, male Golden Retriever dog was presented for evaluation of a nasal mass and approximately 30 firm, raised, variably ulcerated dermal and subcutaneous masses. Histopathology of both nasal and multiple skin masses revealed multiple nonencapsulated, infiltrative masses comprising clusters, anastomosing trabeculae, and packets of neoplastic, round to ovoid, hyperchromatic cells with marked nuclear molding. Surrounding the neoplastic cells was a marked stromal response in which many of the spindle-shaped cells expressed muscle-specific actin and had ultrastructural features consistent with myofibroblasts. A literature search indicates that this is the first report in a peer-reviewed journal of cutaneous metastasis of a nasal neuroendocrine tumor in any domestic animal species.
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Affiliation(s)
- J W Koehler
- Auburn University College of Veterinary Medicine, Department of Pathobiology, Auburn, Alabama, USA.
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17
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Joiner KS, Smith AN, Henderson RA, Brawner WR, Spangler EA, Sartin EA. Multicentric cutaneous neuroendocrine (Merkel cell) carcinoma in a dog. Vet Pathol 2010; 47:1090-4. [PMID: 20634406 DOI: 10.1177/0300985810375945] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multicentric cutaneous neuroendocrine (Merkel cell) carcinoma was diagnosed in a 5-year-old castrated male Keeshond dog with multiple firm nodular cutaneous masses. The neoplastic tissue locally effaced the periadnexal and deep dermis and consisted of densely cellular confluent clusters of round to polygonal cells supported by a delicate fibrovascular stroma. The cells were moderately immunoreactive with chromogranin A, synaptophysin, and cytokeratin. Ultrastructurally, the cells had characteristic membrane-bound dense-core neuroendocrine granules approximately 120 nm in diameter and randomly dispersed throughout the cytoplasm. Effacement of dermal structures and multicentric distribution suggested low-grade malignant phenotype. These findings contrast with the typical benign behavior of canine cutaneous neuroendocrine tumors.
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Affiliation(s)
- K S Joiner
- Department of Pathobiology, 166 Greene Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5519, USA.
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18
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O'Brien PM, Davies MJ, Scurry JP, Smith AN, Barton CA, Henderson MJ, Saunders DN, Gloss BS, Patterson KI, Clancy JL, Heinzelmann-Schwarz VA, Murali R, Scolyer RA, Zeng Y, Williams ED, Scurr L, DeFazio A, Quinn D, Watts CKW, Hacker NF, Henshall SM, Sutherland RL. Erratum: The E3 ubiquitin ligase EDD is an adverse prognostic factor for serous epithelial ovarian cancer and modulates cisplatin resistance in vitro. Br J Cancer 2008. [PMCID: PMC2410105 DOI: 10.1038/sj.bjc.6604419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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19
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O'Brien PM, Davies MJ, Scurry JP, Smith AN, Barton CA, Henderson MJ, Saunders DN, Gloss BS, Patterson KI, Clancy JL, Heinzelmann-Schwarz VA, Murali R, Scolyer RA, Zeng Y, Williams ED, Scurr L, Defazio A, Quinn DI, Watts CKW, Hacker NF, Henshall SM, Sutherland RL. The E3 ubiquitin ligase EDD is an adverse prognostic factor for serous epithelial ovarian cancer and modulates cisplatin resistance in vitro. Br J Cancer 2008; 98:1085-93. [PMID: 18349819 PMCID: PMC2275489 DOI: 10.1038/sj.bjc.6604281] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Despite a high initial response rate to first-line platinum/paclitaxel chemotherapy, most women with epithelial ovarian cancer relapse with recurrent disease that becomes refractory to further cytotoxic treatment. We have previously shown that the E3 ubiquitin ligase, EDD, a regulator of DNA damage responses, is amplified and overexpressed in serous ovarian carcinoma. Given that DNA damage pathways are linked to platinum resistance, the aim of this study was to determine if EDD expression was associated with disease recurrence and platinum sensitivity in serous ovarian cancer. High nuclear EDD expression, as determined by immunohistochemistry in a cohort of 151 women with serous ovarian carcinoma, was associated with an approximately two-fold increased risk of disease recurrence and death in patients who initially responded to first-line chemotherapy, independently of disease stage and suboptimal debulking. Although EDD expression was not directly correlated with relative cisplatin sensitivity of ovarian cancer cell lines, sensitivity to cisplatin was partially restored in platinum-resistant A2780-cp70 ovarian cancer cells following siRNA-mediated knockdown of EDD expression. These results identify EDD as a new independent prognostic marker for outcome in serous ovarian cancer, and suggest that pathways involving EDD, including DNA damage responses, may represent new therapeutic targets for chemoresistant ovarian cancer.
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Affiliation(s)
- P M O'Brien
- Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales 2010, Australia .
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Heinzelmann-Schwarz VA, Gardiner-Garden M, Henshall SM, Scurry JP, Scolyer RA, Smith AN, Bali A, Bergh PV, Baron-Hay S, Scott C, Fink D, Hacker NF, Sutherland RL, O'Brien PM. A distinct molecular profile associated with mucinous epithelial ovarian cancer. Br J Cancer 2006; 94:904-13. [PMID: 16508639 PMCID: PMC2361366 DOI: 10.1038/sj.bjc.6603003] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mucinous epithelial ovarian cancers (MOC) are clinically and morphologically distinct from the other histological subtypes of ovarian cancer. To determine the genetic basis of MOC and to identify potential tumour markers, gene expression profiling of 49 primary ovarian cancers of different histological subtypes was performed using a customised oligonucleotide microarray containing >59 000 probesets. The results show that MOC express a genetic profile that both differs and overlaps with other subtypes of epithelial ovarian cancer. Concordant with its histological phenotype, MOC express genes characteristic of mucinous carcinomas of varying epithelial origin, including intestinal carcinomas. Differences in gene expression between MOC and other histological subtypes of ovarian cancer were confirmed by RT–PCR and/or immunohistochemistry. In particular, galectin 4 (LGALS4) was highly and specifically expressed in MOC, but expressed at lower levels in benign mucinous cysts and borderline (atypical proliferative) tumours, supporting a malignant progression model of MOC. Hence LGALS4 may have application as an early and differential diagnostic marker of MOC.
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Affiliation(s)
- V A Heinzelmann-Schwarz
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
- Division of Gynecology, University Hospital Zurich, Switzerland
| | - M Gardiner-Garden
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - S M Henshall
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - J P Scurry
- South Eastern Area Laboratory Service, Prince of Wales Hospital, Randwick, NSW 2031, Australia
| | - R A Scolyer
- Department of Anatomical Pathology, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - A N Smith
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - A Bali
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - P Vanden Bergh
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - S Baron-Hay
- Kolling Institute of Medical Research, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - C Scott
- Kolling Institute of Medical Research, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
| | - D Fink
- Division of Gynecology, University Hospital Zurich, Switzerland
| | - N F Hacker
- Gynaecological Cancer Centre, Royal Hospital for Women, Randwick, NSW 2031, Australia
| | - R L Sutherland
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - P M O'Brien
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
- Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia.
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21
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Smith AN. An illustrated guide to gastrointestinal motility. D. Kumar, S. Gustavsson. 255 × 195mm. Pp. 470. Illustrated. 1988. Chichester: John Wiley and Sons. £65.00. Br J Surg 2005. [DOI: 10.1002/bjs.1800761251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- A N Smith
- Western General Hospital, Edinburgh EH4 2XU, UK
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Abstract
Infection with HIV may develop to AIDS at different rates in different individuals, with a spectrum varying from rapid progression to long-term non-progression. The variable course of HIV-1 infection causes emotional trauma for the infected person and complicates the design and interpretation of therapeutic trials because of unrecognized differences in prognosis. Owing to the variable clinical expression of HIV infection, the use of non-clinical disease markers has become important to patient management. Thus, it is essential to have tests which can accurately assess the stage of infection in an individual, as well as predict its course and monitor its progression. These laboratory tests are valuable during the period of clinical latency and subsequently supplement various clinical parameters.
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Affiliation(s)
- P Kiepiela
- Nelson R Mandela School of Medicine, University of Kwazulu-Natal, HIV Pathogenesis Programme, DDMRI, 719 Umbilo Road, Congella, Durban, 4013 Natal, South Africa.
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Abstract
In recent years, several inhibitors that prevent caspase activation and apoptosis have emerged. At high doses, however, these inhibitors can have nonspecific effects and/or become cytotoxic. In this study, we determined the effectiveness of broad spectrum caspase inhibitors to prevent apoptosis. A carboxy terminal phenoxy group conjugated to the amino acids valine and aspartate (Q-VD-OPh) potently inhibited apoptosis. Q-VD-OPh was significantly more effective in preventing apoptosis than the widely used inhibitors, ZVAD-fmk and Boc-D-fmk, and was also equally effective in preventing apoptosis mediated by the three major apoptotic pathways, caspase 9/3, caspase 8/10, and caspase 12. In addition to the increased effectiveness, Q-VD-OPh was not toxic to cells even at extremely high concentrations. Our data indicate that the specificity, effectiveness, and reduced toxicity of caspase inhibitors can be significantly enhanced using carboxyterminal o-phenoxy groups and may have important uses in vivo.
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Affiliation(s)
- T M Caserta
- Department of Physiology and Biophysics, Wright State University School of Medicine, Dayton, Ohio 45435, USA
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24
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Cohen M, Sartin EA, Whitley EM, Whitley RD, Smith AN, Brawner WR, Henderson R, Behrend EN. Ocular metastasis of a vaccine-associated fibrosarcoma in a cat. Vet Comp Oncol 2003; 1:232-40. [PMID: 19379185 DOI: 10.1111/j.1476-5810.2003.00031.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A 6-year-old, neutered male domestic shorthair cat was evaluated for a recurrent vaccine-associated fibrosarcoma. The cat had three excisions of the tumour prior to presentation and was referred for radiation therapy. Ten months following treatment with radiation therapy, the cat was presented again for a cloudy appearance to the eye. An exenteration was performed, and biopsy revealed fibrosarcoma. At the same time, two discrete pulmonary nodules were identified on thoracic radiographs. Two doses of doxorubicin (20 mg/m(2)) and cyclophosphamide (100 mg/m(2)) were administered intravenously 3 weeks apart. Despite treatment, the pulmonary nodule doubled in size. This case represents the first antemortem report of ocular metastasis of a vaccine-associated sarcoma and supports the highly aggressive nature of these tumours.
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Affiliation(s)
- M Cohen
- Comparative Oncology Program, Animal Cancer Treatment Unit, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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25
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Madala ND, Naicker S, Singh B, Naidoo M, Smith AN, Rughubar K. The pathogenesis of membranoproliferative glomerulonephritis in KwaZulu-Natal, South Africa is unrelated to hepatitis C virus infection. Clin Nephrol 2003; 60:69-73. [PMID: 12940606 DOI: 10.5414/cnp60069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Idiopathic membranoproliferative glomerulonephritis (MPGN) is a well-defined clinicopathological entity with a poor prognosis, with 50% of patients progressing to end stage renal disease (ESRD) within 10 years. It was reported in about 36% of adult Black patients with nephrotic syndrome in our center previously [Seedat et al. 1988]. Hepatitis C virus (HCV) infection has been shown to be associated with cryoglobulinemic as well as non-cryoglobulinemic (or idiopathic glomerulonephritis). The aim of this study was to determine whether an association exists between HCV infection and idiopathic MPGN in a population with a relatively high prevalence of MPGN. We studied adult patients referred with glomerular disease over a two-year period, 104 patients had primary glomerulonephritis. All 23 (22%) patients with idiopathic MPGN were enrolled, as well as 32 age-matched patients presenting with other primary glomerular diseases. We examined serum from all 55 patients for evidence of HCV antibodies and HCV RNA. None of the 55 patients showed evidence of HCV infection. Chronic renal failure was present in 82.6% of the patients with idiopathic MPGN and it was advanced in 52,2%, who either were dialysis-requiring at presentation or progressed to ESRD soon thereafter; 30.4% had moderate chronic renal failure, while only 17.4% had normal renal function. HCV infection is not associated with idiopathic MPGN in our patients. Idiopathic MPGN remains an idiopathic disease, possibly with a poor prognosis in our population.
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Affiliation(s)
- N D Madala
- Department of Medicine, Nelson R. Mandela School of Medicine, University of Natal, Durban, South Africa.
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26
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Abstract
Alpha II-spectrin is one of the major proteins responsible for maintaining the cytoskeletal integrity of the cell. The caspase 3-mediated cleavage of alpha II-spectrin during apoptotic cell death may play an important role in altering membrane stability and the formation of apoptotic bodies. In this study, we identified the primary caspase 3 cleavage site in alpha II-spectrin. We found that the transcriptional inhibitor, actinomycin D, induced caspase 3 activation and that caspase 3 activation is coincident with the cleavage of alpha II-spectrin protein at a primary cleavage site. Deletion analysis and site directed mutagenesis identified the primary cleavage site in alpha II spectrin at amino acid 1185 (DETD). The primary caspase 3 cleavage site in alpha II spectrin is conserved in immature and mature B cells. Our results indicate that alpha II-spectrin is initially cleaved at a caspase 3 consensus site and this primary event likely alters the structural conformation of the protein exposing subsequent cleavage sites and altering cytoskeletal integrity. Identification of the primary cleavage site for caspase 3 may help to elucidate the role of alpha II-spectrin in membrane stability and apoptosis as well as provide new insights into alpha II-spectrin autoantibody formation associated with the autoimmune disease, Sjögren's syndrome.
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Affiliation(s)
- S T Williams
- Department of Physiology & Biophysics, Wright State University School of Medicine, Dayton, OH 45435, USA
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27
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Abstract
In recent years, several inhibitors that prevent caspase activation and apoptosis have emerged. At high doses, however, these inhibitors can have nonspecific effects and/or become cytotoxic. In this study, we determined the effectiveness of broad spectrum caspase inhibitors to prevent apoptosis. A carboxy terminal phenoxy group conjugated to the amino acids valine and aspartate (Q-VD-OPh) potently inhibited apoptosis. Q-VD-OPh was significantly more effective in preventing apoptosis than the widely used inhibitors, ZVAD-fmk and Boc-D-fmk, and was also equally effective in preventing apoptosis mediated by the three major apoptotic pathways, caspase 9/3, caspase 8/10, and caspase 12. In addition to the increased effectiveness, Q-VD-OPh was not toxic to cells even at extremely high concentrations. Our data indicate that the specificity, effectiveness, and reduced toxicity of caspase inhibitors can be significantly enhanced using carboxyterminal o-phenoxy groups and may have important uses in vivo.
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Affiliation(s)
- T M Caserta
- Department of Physiology and Biophysics, Wright State University School of Medicine, Dayton, Ohio 45435, USA
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28
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Stover EH, Borthwick KJ, Bavalia C, Eady N, Fritz DM, Rungroj N, Giersch ABS, Morton CC, Axon PR, Akil I, Al-Sabban EA, Baguley DM, Bianca S, Bakkaloglu A, Bircan Z, Chauveau D, Clermont MJ, Guala A, Hulton SA, Kroes H, Li Volti G, Mir S, Mocan H, Nayir A, Ozen S, Rodriguez Soriano J, Sanjad SA, Tasic V, Taylor CM, Topaloglu R, Smith AN, Karet FE. Novel ATP6V1B1 and ATP6V0A4 mutations in autosomal recessive distal renal tubular acidosis with new evidence for hearing loss. J Med Genet 2002; 39:796-803. [PMID: 12414817 PMCID: PMC1735017 DOI: 10.1136/jmg.39.11.796] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Autosomal recessive distal renal tubular acidosis (rdRTA) is characterised by severe hyperchloraemic metabolic acidosis in childhood, hypokalaemia, decreased urinary calcium solubility, and impaired bone physiology and growth. Two types of rdRTA have been differentiated by the presence or absence of sensorineural hearing loss, but appear otherwise clinically similar. Recently, we identified mutations in genes encoding two different subunits of the renal alpha-intercalated cell's apical H(+)-ATPase that cause rdRTA. Defects in the B1 subunit gene ATP6V1B1, and the a4 subunit gene ATP6V0A4, cause rdRTA with deafness and with preserved hearing, respectively. We have investigated 26 new rdRTA kindreds, of which 23 are consanguineous. Linkage analysis of seven novel SNPs and five polymorphic markers in, and tightly linked to, ATP6V1B1 and ATP6V0A4 suggested that four families do not link to either locus, providing strong evidence for additional genetic heterogeneity. In ATP6V1B1, one novel and five previously reported mutations were found in 10 kindreds. In 12 ATP6V0A4 kindreds, seven of 10 mutations were novel. A further nine novel ATP6V0A4 mutations were found in "sporadic" cases. The previously reported association between ATP6V1B1 defects and severe hearing loss in childhood was maintained. However, several patients with ATP6V0A4 mutations have developed hearing loss, usually in young adulthood. We show here that ATP6V0A4 is expressed within the human inner ear. These findings provide further evidence for genetic heterogeneity in rdRTA, extend the spectrum of disease causing mutations in ATP6V1B1 and ATP6V0A4, and show ATP6V0A4 expression within the cochlea for the first time.
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Affiliation(s)
- E H Stover
- Department of Medical Genetics, University of Cambridge, UK
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Hudson CP, Moodley J, Smith AN. Stage of the epidemic and viral phenotype should influence recommendations regarding mother-to-child transmission of HIV-1. Lancet Infect Dis 2002; 2:115-9. [PMID: 11901643 DOI: 10.1016/s1473-3099(02)00186-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This article argues for a new approach to use of nevirapine in the prevention of vertical transmission of HIV-1. Existing antenatal surveillance should be strengthened to plan geographical allocation, and subsequent evaluation, of a "nevirapine plus" programme. As the epidemic evolves the programme should also and, ideally, care should be tailored to individual women. Underpinning this approach is evidence that a more virulent viral phenotype appears in many patients with advanced HIV-1 infection. This phenotype will become more common at the population level as the epidemic progresses. As efficacy of zidovudine correlates with viral phenotype, and use of the drug may alter phenotype, there is an urgent need for a replacement that is safe to use with nevirapine.
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Affiliation(s)
- C P Hudson
- Department of Virology, Nelson R Mandela Medical School, University of Natal, Durban, KwaZulu-Natal, South Africa
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30
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Cohen M, Wright JC, Brawner WR, Smith AN, Henderson R, Behrend EN. Use of surgery and electron beam irradiation, with or without chemotherapy, for treatment of vaccine-associated sarcomas in cats: 78 cases (1996-2000). J Am Vet Med Assoc 2001; 219:1582-9. [PMID: 11759998 DOI: 10.2460/javma.2001.219.1582] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate responses of cats with vaccine-associated sarcomas to treatment with surgery and radiotherapy, with or without adjunctive chemotherapy. DESIGN Retrospective study. ANIMALS 76 cats (78 tumors). PROCEDURE Medical records were reviewed. Factors potentially associated with survival time, time to recurrence, and time to development of metastases were evaluated. RESULTS Following excision, electron beam radiation, and, in some cases, chemotherapy, 32 (41%) cats experienced recurrence, and 9 (12%) cats developed metastases. One- and 2-year survival rates were 86 and 44%, respectively. Median survival time from onset of disease was 730 days (range, 30 to 2,014 days). Median disease-free interval was 405 days (range, 30 to 925 days). Cats that underwent only 1 surgery prior to radiotherapy had a lower recurrence rate than did cats that underwent > 1 surgery and had a significantly longer disease-free interval. Survival time and disease-free interval decreased as time between surgery and the start of radiotherapy increased. Cats that developed metastases had significantly shorter survival times and disease-free intervals than did cats that did not develop metastases. Castrated male cats had a significantly shorter survival time than did spayed female cats. Cats with larger tumors prior to the first surgery had shorter survival times. Twenty-six cats received chemotherapy in addition to surgery and radiotherapy. Whether cats received chemotherapy was not associated with recurrence rate, metastasis rate, or survival time. CONCLUSIONS AND CLINICAL RELEVANCE Results suggest that excision followed by electron beam irradiation may be beneficial for treatment of cats with vaccine-associated sarcomas. Extent of excision prior to radiotherapy did not seem to be associated with recurrence rate.
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Affiliation(s)
- M Cohen
- Animal Cancer Treatment Unit, College of Veterinary Medicine, Auburn University, AL 36849-5523, USA
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31
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Smith AN, Finberg KE, Wagner CA, Lifton RP, Devonald MA, Su Y, Karet FE. Molecular cloning and characterization of Atp6n1b: a novel fourth murine vacuolar H+-ATPase a-subunit gene. J Biol Chem 2001; 276:42382-8. [PMID: 11495928 DOI: 10.1074/jbc.m107267200] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The 116-kDa a-subunit of the vacuolar proton pump (H(+)-ATPase) exists as several isoforms encoded by different genes and with different patterns of tissue expression. Its function within the multisubunit pump complex has yet to be elucidated. To date, three isoforms have been identified in mouse (designated a1-a3). We now report the cloning and characterization of Atp6n1b, encoding a novel fourth murine isoform (a4). Murine a4 has 833 residues and shows 85% amino acid identity to the human kidney-specific ATP6N1B protein in which loss-of-function alterations cause autosomal recessive distal renal tubular acidosis. The human and murine genes have similar genomic organization; furthermore, Atp6n1b maps to a region of mouse chromosome 6 that is syntenic with the segment of human 7q33-34 containing ATP6N1B. Together these findings establish the two genes as orthologs. The mouse a4 protein is 61, 52, and 47% identical to a1, a2, and a3, respectively. Phylogenetic analysis confirms that among vertebrates there are four a-subunit families, with a4 most resembling a1. Northern blot analysis of Atp6n1b reveals a 3.7-kilobase a4 transcript in kidney but not other major organs, and a reverse transcription polymerase chain reaction in 12 mouse tissues detects expression in kidney alone. Immunofluorescence studies in murine kidney demonstrate high intensity a4 staining at the surface of intercalated cells, with additional expression in the proximal tubule (not previously reported in human kidney). Similar apical a4 immunostaining is also present in male genital tissue. Identification of this novel murine kidney-enriched 116-kDa a-subunit provides a molecular tool for investigation of the currently unknown role of this protein, which is essential for proper function of the apical renal vacuolar H(+)-ATPase in man.
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Affiliation(s)
- A N Smith
- Department of Medical Genetics, Cambridge Institute for Medical Research, Box 139 Addenbrooke's Hospital, Cambridge CB2 2XY, United Kingdom
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Bishop KS, Blumberg L, Trollip AP, Smith AN, Roux L, York DF, Kiepiela P. Characterisation of the pncA gene in Mycobacterium tuberculosis isolates from Gauteng, South Africa. Int J Tuberc Lung Dis 2001; 5:952-7. [PMID: 11605890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
SETTING The use of pyrazinamide (PZA) is important for the treatment of Mycobacterium tuberculosis as it is bactericidal to semi-dormant mycobacteria that are not affected by other drugs. The incidence of resistance to PZA and other drugs used in the treatment of M. tuberculosis is increasing in South Africa. OBJECTIVE To characterise the pncA gene of M. tuberculosis isolates from Gauteng, South Africa, and to develop a rapid diagnostic method. DESIGN The pncA gene and the putative regulatory gene were characterised by sequence analysis in a total of six PZA susceptible and 15 resistant isolates. The association with classical PZA susceptibility testing and PZase activity was determined. RESULTS All PZA-resistant isolates were PZase negative as well as resistant to at least one other anti-tuberculosis drugs. Mutations were identified throughout the length of the pncA gene in 10/15 PZA-resistant isolates. Five lacked PZase activity, but the wild type pncA sequence was present. In all six PZase-positive strains, a PZA-susceptible pattern was obtained on BACTEC and the wild type pncA sequence was present. CONCLUSION Sequencing is an effective means to identify mutations in the pncA gene in M. tuberculosis and therefore resistance to PZA. The fact that some PZA-resistant M. tuberculosis isolates lack mutations in the pncA gene suggests that alternative mechanisms for drug resistance exist. In PZase negative strains with no genetic changes which are resistant to 100 microg/ml and susceptible to 300 microg/ml, 300 microg/ml may be a more reliable breakpoint.
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Affiliation(s)
- K S Bishop
- Department of Virology, Faculty of Medicine, University of Natal, Durban, KwaZulu-Natal, South Africa
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33
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Johnson GC, Esposito L, Barratt BJ, Smith AN, Heward J, Di Genova G, Ueda H, Cordell HJ, Eaves IA, Dudbridge F, Twells RC, Payne F, Hughes W, Nutland S, Stevens H, Carr P, Tuomilehto-Wolf E, Tuomilehto J, Gough SC, Clayton DG, Todd JA. Haplotype tagging for the identification of common disease genes. Nat Genet 2001; 29:233-7. [PMID: 11586306 DOI: 10.1038/ng1001-233] [Citation(s) in RCA: 908] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Genome-wide linkage disequilibrium (LD) mapping of common disease genes could be more powerful than linkage analysis if the appropriate density of polymorphic markers were known and if the genotyping effort and cost of producing such an LD map could be reduced. Although different metrics that measure the extent of LD have been evaluated, even the most recent studies have not placed significant emphasis on the most informative and cost-effective method of LD mapping-that based on haplotypes. We have scanned 135 kb of DNA from nine genes, genotyped 122 single-nucleotide polymorphisms (SNPs; approximately 184,000 genotypes) and determined the common haplotypes in a minimum of 384 European individuals for each gene. Here we show how knowledge of the common haplotypes and the SNPs that tag them can be used to (i) explain the often complex patterns of LD between adjacent markers, (ii) reduce genotyping significantly (in this case from 122 to 34 SNPs), (iii) scan the common variation of a gene sensitively and comprehensively and (iv) provide key fine-mapping data within regions of strong LD. Our results also indicate that, at least for the genes studied here, the current version of dbSNP would have been of limited utility for LD mapping because many common haplotypes could not be defined. A directed re-sequencing effort of the approximately 10% of the genome in or near genes in the major ethnic groups would aid the systematic evaluation of the common variant model of common disease.
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Affiliation(s)
- G C Johnson
- JDRF/WT Diabetes and Inflammation Laboratory, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, UK
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34
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Smith AN, Wright JC, Brawner WR, LaRue SM, Fineman L, Hogge GS, Kitchell BE, Hohenhaus AE, Burk RL, Dhaliwal RS, Duda LE. Radiation therapy in the treatment of canine and feline thymomas: a retrospective study (1985-1999). J Am Anim Hosp Assoc 2001; 37:489-96. [PMID: 11563450 DOI: 10.5326/15473317-37-5-489] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A retrospective study was performed of 17 dogs and seven cats with various stages of thymoma treated with radiation alone or as an adjunctive therapy. Analysis revealed an overall response rate of 75% (15/20 evaluable cases). Partial (i.e., >50% reduction in tumor size) and complete (i.e., no detectable tumor) responses were included. Complete responses were rare (4/20). Three of five animals with stable disease (i.e., <50% change in tumor size) had improvements in clinical signs, despite lack of measurable response. A median survival time of 248 days (range, 93 to 1,657+ days) was achieved in dogs, and a median survival time of 720 days (range, 485 to 1,825+ days) was achieved in cats. Radiation therapy appears to be useful in the management of invasive thymomas in dogs and cats.
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Affiliation(s)
- A N Smith
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Alabama 36849, USA
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35
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Hudson CP, Smith AN, Moodley J. To test or not to test--ethical dilemmas and practical realities in the use of co-trimoxazole and nevirapine in HIV-infected adults. S Afr Med J 2001; 91:656-8. [PMID: 11584779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Affiliation(s)
- C P Hudson
- Department of Virology, Nelson R Mandela School of Medicine, University of Natal, Durban
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36
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Abstract
The placenta is formed by developing trophoblast cells to facilitate fluid, gas and nutrient exchange with the mother. Inappropriate trophoblast responsiveness can lead to life threatening complications during pregnancy including intrauterine growth retardation, pre-eclampsia, spontaneous abortion and malignancy that could lead to fetal loss. Transforming growth factor beta (TGFbeta) is a multifunctional cytokine required for embryonic development and is an important regulator of human trophoblast function. Although TGFbeta is critical for placental and embryonic development, there are currently no established TGFbeta-responsive human trophoblast-derived cell lines available to study the mechanisms by which TGFbeta regulates trophoblast function. Our studies have examined the transformed human trophoblast-derived cell line, ED27, to determine if it is responsive to TGFbeta. Our data indicate that TGFbeta dose responsively and reversibly inhibits cell growth in ED27 cells and induces classic TGFbeta response genes, fibronectin and plasminogen activator inhibitor 1 (PAI-1). TGFbeta also induces an inhibitor of trophoblast invasion, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in ED27 cells. Our studies have identified a human trophoblast-derived cell line that parallels isolated primary human trophoblasts in their responses to TGFbeta. This cell line may provide us with the opportunity to determine TGFbeta-mediated responses on human trophoblast functions not previously possible.
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Affiliation(s)
- A N Smith
- Department of Physiology and Cell Biophysics, Wright State University School of Medicine, Dayton, Ohio 45435, USA
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38
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Smith AN, Skaug J, Choate KA, Nayir A, Bakkaloglu A, Ozen S, Hulton SA, Sanjad SA, Al-Sabban EA, Lifton RP, Scherer SW, Karet FE. Mutations in ATP6N1B, encoding a new kidney vacuolar proton pump 116-kD subunit, cause recessive distal renal tubular acidosis with preserved hearing. Nat Genet 2000; 26:71-5. [PMID: 10973252 DOI: 10.1038/79208] [Citation(s) in RCA: 268] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The multi-subunit H+-ATPase pump is present at particularly high density on the apical (luminal) surface of -intercalated cells of the cortical collecting duct of the distal nephron, where vectorial proton transport is required for urinary acidification. The complete subunit composition of the apical ATPase, however, has not been fully agreed upon. Functional failure of -intercalated cells results in a group of disorders, the distal renal tubular acidoses (dRTA), whose features include metabolic acidosis accompanied by disturbances of potassium balance, urinary calcium solubility, bone physiology and growth. Mutations in the gene encoding the B-subunit of the apical pump (ATP6B1) cause dRTA accompanied by deafness. We previously localized a gene for dRTA with preserved hearing to 7q33-34 (ref. 4). We report here the identification of this gene, ATP6N1B, which encodes an 840 amino acid novel kidney-specific isoform of ATP6N1A, the 116-kD non-catalytic accessory subunit of the proton pump. Northern-blot analysis demonstrated ATP6N1B expression in kidney but not other main organs. Immunofluorescence studies in human kidney cortex revealed that ATP6N1B localizes almost exclusively to the apical surface of -intercalated cells. We screened nine dRTA kindreds with normal audiometry that linked to the ATP6N1B locus, and identified different homozygous mutations in ATP6N1B in eight. These include nonsense, deletion and splice-site changes, all of which will truncate the protein. Our findings identify a new kidney-specific proton pump 116-kD accessory subunit that is highly expressed in proton-secreting cells in the distal nephron, and illustrate its essential role in normal vectorial acid transport into the urine by the kidney.
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MESH Headings
- Acidosis, Renal Tubular/genetics
- Acidosis, Renal Tubular/metabolism
- Acidosis, Renal Tubular/urine
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Adolescent
- Adult
- Amino Acid Sequence
- Audiometry
- Blotting, Northern
- Brain/metabolism
- Child
- Child, Preschool
- Chromosomes, Human, Pair 7
- Contig Mapping
- DNA, Complementary/metabolism
- Exons
- Female
- Gene Deletion
- Genes, Recessive
- Genetic Linkage
- Genetic Markers
- Hearing/genetics
- Hearing/physiology
- Homozygote
- Humans
- Kidney/metabolism
- Kidney/pathology
- Kidney Cortex/metabolism
- Male
- Microscopy, Fluorescence
- Mitochondrial Proton-Translocating ATPases
- Models, Genetic
- Molecular Sequence Data
- Mutation
- Pedigree
- Physical Chromosome Mapping
- Polymorphism, Genetic
- Polymorphism, Single-Stranded Conformational
- Pregnancy Proteins
- Protein Biosynthesis
- Protein Isoforms
- Proton Pumps/biosynthesis
- Proton Pumps/chemistry
- Proton Pumps/genetics
- Proton-Translocating ATPases
- RNA Splicing
- Recombination, Genetic
- Sequence Homology, Amino Acid
- Suppressor Factors, Immunologic
- Tissue Distribution
- Vacuolar Proton-Translocating ATPases
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Affiliation(s)
- A N Smith
- Wellcome Trust Centre for Molecular Mechanisms in Disease, University of Cambridge, Cambridge, UK
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Kiepiela P, Bishop KS, Smith AN, Roux L, York DF. Genomic mutations in the katG, inhA and aphC genes are useful for the prediction of isoniazid resistance in Mycobacterium tuberculosis isolates from Kwazulu Natal, South Africa. Tuber Lung Dis 2000; 80:47-56. [PMID: 10897383 DOI: 10.1054/tuld.1999.0231] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Genotypic analysis of isoniazid (INH) resistance in 79 isolates of M. tuberculosis (MTB) was undertaken by PCR-single strand conformation polymorphism (SSCP), Msp1 restriction enzyme analysis and sequence analysis of specific regions of three genes (part of the coding sequence of katG, and promoter regions of the inhA operon and ahpC) in order to determine the particular allelic variants within these genes. The epidemiologic relatedness was determined using IS6110 and polymorphic G-C region (PGRS (MTB484(1)) based restriction fragment length polymorphism (RFLP). Mutations in katG, inhA locus and ahpC were identified in 77/79, 19/79 and 10/79 isolates respectively. The ability of PCR-SSCP to detect mutations associated with INH resistance in katG, inhA and ahpC genes was 100% (CI 91.2-99.7%), 98.7% (CI 74.0-99.9%), and 100% (CI 69.2-100%) respectively. Specificity was 100%. All isolates with mutations in the 209 bp fragment of the MTB katG gene containing the Ser315Thr codon were positive by PCR-RFLP using Msp1 enzyme restriction analysis. Sixteen of 19 isolates with alterations on the 3' end of the ribosome binding site upstream of mabA in inhA locus simultaneously harbored Ser315Thr mutations in KatG. In 9/10 isolates, mutations in the ahpC promoter region were located in the 105 bp oxyR-ahpC intergenic region. None of 17 INH drug susceptible isolates harbored mutations in any of the three genetic regions, although the katG1 allele (Arg 463 Leu) was present in one isolate. Characterization by IS6110/PGRS(MTB484(1))RFLP analysis revealed that a number of drug resistant clones are widespread in the community. We conclude that the frequency of the Ser315Thr katG mutation in the local strain population makes the PCR-RFLP MTB katG assay a reliable, rapid and useful method for detecting INH resistance.
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Affiliation(s)
- P Kiepiela
- Department of Virology, University of Natal, Faculty of Medicine, Durban, South Africa.
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Smith AN, Spencer JA, Stringfellow JS, Vygantas KR, Welch JA. Disseminated infection with Phialemonium obovatum in a German shepherd dog. J Am Vet Med Assoc 2000; 216:708-12, 684-5. [PMID: 10707686 DOI: 10.2460/javma.2000.216.708] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A 4-year-old spayed female German Shepherd Dog was evaluated because of left forelimb lameness. A fungal granuloma on the distal portion of the radius was determined to be the cause of the lameness; the infecting organism was identified as Phialemonium obovatum. Despite aggressive treatment with amphotericin B, itraconazole, and ketoconazole and curettage of the local area, the dog developed systemic disease and was euthanatized 5 months after initial evaluation. Immune dysfunction may have played a role in development of disseminated disease, because although serum concentrations of total IgG, IgA, and IgM were within or greater than reference ranges, results of lymphocyte proliferation assays were abnormal, which indicated cellular immune dysfunction. Infection with Phialemonium obovatum should be considered as a differential diagnosis when branching fungal organisms are detected during histologic, cytologic, or microbiologic evaluation of tissue specimens.
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Affiliation(s)
- A N Smith
- Department of Small Animal Surgery, College of Veterinary Medicine, Auburn University, AL 36849, USA
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41
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Mein CA, Barratt BJ, Dunn MG, Siegmund T, Smith AN, Esposito L, Nutland S, Stevens HE, Wilson AJ, Phillips MS, Jarvis N, Law S, de Arruda M, Todd JA. Evaluation of single nucleotide polymorphism typing with invader on PCR amplicons and its automation. Genome Res 2000; 10:330-43. [PMID: 10720574 PMCID: PMC311429 DOI: 10.1101/gr.10.3.330] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Large-scale pharmacogenetics and complex disease association studies will require typing of thousands of single-nucleotide polymorphisms (SNPs) in thousands of individuals. Such projects would benefit from a genotyping system with accuracy >99% and a failure rate <5% on a simple, reliable, and flexible platform. However, such a system is not yet available for routine laboratory use. We have evaluated a modification of the previously reported Invader SNP-typing chemistry for use in a genotyping laboratory and tested its automation. The Invader technology uses a Flap Endonuclease for allele discrimination and a universal fluorescence resonance energy transfer (FRET) reporter system. Three hundred and eighty-four individuals were genotyped across a panel of 36 SNPs and one insertion/deletion polymorphism with Invader assays using PCR product as template, a total of 14,208 genotypes. An average failure rate of 2.3% was recorded, mostly associated with PCR failure, and the typing was 99.2% accurate when compared with genotypes generated with established techniques. An average signal-to-noise ratio (9:1) was obtained. The high degree of discrimination for single base changes, coupled with homogeneous format, has allowed us to deploy liquid handling robots in a 384-well microtitre plate format and an automated end-point capture of fluorescent signal. Simple semiautomated data interpretation allows the generation of approximately 25,000 genotypes per person per week, which is 10-fold greater than gel-based SNP typing and microsatellite typing in our laboratory. Savings on labor costs are considerable. We conclude that Invader chemistry using PCR products as template represents a useful technology for typing large numbers of SNPs rapidly and efficiently.
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Affiliation(s)
- C A Mein
- Wellcome Trust Centre for the Study of Molecular Mechanisms in Disease, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2XY UK
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42
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Abstract
A one-year-old, intact male, 28-kg, mixed-breed dog developed neurological episodes consistent with emboli. An acquired III/VI holosystolic heart murmur was ausculted in the mitral area, and valvular endocarditis with pulmonic and aortic insufficiency were noted at echocardiographic examination. An abnormal communication (i.e., fistula) between the left ventricular outflow tract (LVOT) and the left atrium adjacent to the mitral valve annulus was noted with Doppler imaging and confirmed with angiography. Infective valvular endocarditis was confirmed based on two of three blood cultures being positive for Staphylococcus intermedius. In humans, a sequela to infective endocarditis of the aortic or mitral valve, or both, is rupture of the mitral-aortic intervalvular fibrosa, resulting in a communication between the LVOT and the left atrium. This is the first report of this sequela in the dog.
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Affiliation(s)
- A N Smith
- Small Animal Teaching Hospital, College of Veterinary Medicine, Auburn University, Alabama 36849-5523, USA
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Hostetler JL, Smith AN, Czajkowsky DM, Norris PM. Measurement of the electron-phonon coupling factor dependence on film thickness and grain size in Au, Cr, and Al. Appl Opt 1999; 38:3614-3620. [PMID: 18319965 DOI: 10.1364/ao.38.003614] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Femtosecond thermoreflectance data for thin films and bulk quantities of Au, Cr, and Al are compared with the parabolic two-step thermal diffusion model for the purpose of determining the electron-phonon coupling factor. The thin films were evaporated and sputtered onto different substrates to produce films that vary structurally. The measurement of the electron-phonon coupling factor is shown to be sensitive to grain size and film thickness. The thin-film thermoreflectance data are compared with that of the corresponding bulk material and to a theoretical model relating the coupling rate to the grain-boundary scattering and size effects on the mean free path of the relevant energy carrier.
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Affiliation(s)
- J L Hostetler
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22903, USA
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44
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Mein CA, Esposito L, Dunn MG, Johnson GC, Timms AE, Goy JV, Smith AN, Sebag-Montefiore L, Merriman ME, Wilson AJ, Pritchard LE, Cucca F, Barnett AH, Bain SC, Todd JA. A search for type 1 diabetes susceptibility genes in families from the United Kingdom. Nat Genet 1998; 19:297-300. [PMID: 9662409 DOI: 10.1038/991] [Citation(s) in RCA: 236] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Genetic analysis of a mouse model of major histocompatability complex (MHC)-associated autoimmune type 1 (insulin-dependent) diabetes mellitus (IDDM) has shown that the disease is caused by a combination of a major effect at the MHC and at least ten other susceptibility loci elsewhere in the genome. A genome-wide scan of 93 affected sibpair families (ASP) from the UK (UK93) indicated a similar genetic basis for human type 1 diabetes, with the major genetic component at the MHC locus (IDDM1) explaining 34% of the familial clustering of the disease (lambda(s)=2.5; refs 3,4). In the present report, we have analysed a further 263 multiplex families from the same population (UK263) to provide a total UK data set of 356 ASP families (UK356). Only four regions of the genome outside IDDM1/MHC, which was still the only major locus detected, were not excluded at lambda(s)=3 and lod=-2, of which two showed evidence of linkage: chromosome 10p13-p11 (maximum lod score (MLS)=4.7, P=3x10(-6), lambda(s)=1.56) and chromosome 16q22-16q24 (MLS=3.4, P=6.5x10(-5), lambda(s)=1.6). These and other novel regions, including chromosome 14q12-q21 and chromosome 19p13-19q13, could potentially harbour disease loci but confirmation and fine mapping cannot be pursued effectively using conventional linkage analysis. Instead, more powerful linkage disequilibrium-based and haplotype mapping approaches must be used; such data is already emerging for several type 1 diabetes loci detected initially by linkage.
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Affiliation(s)
- C A Mein
- Wellcome Trust Centre for Human Genetics, Nuffield Department of Surgery, University of Oxford, UK
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Abstract
OBJECTIVES To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant. METHODS Deaths were ascertained through various sources including data tapes from the Texas Department of Health and the national death index files. As many death certificates as possible were secured (304/315) and cause of death assigned. After select exclusions, 222 death certificates were used in the analysis. Causes of death were compared with age, race, and sex specific mortalities for the United States population with a commercial software package (OCMAP Version 2.0). RESULTS There was an excess of deaths from respiratory cancer including the bronchus, trachea, and lung (standardised mortality ratio (SMR) 277 with 95% confidence interval (95% CI) 193 to 385). Four pleural mesotheliomas and two peritoneal mesotheliomas were identified. The analysis also showed an increasing risk of respiratory malignancy with increased duration of exposure including a significant excess of total deaths from respiratory cancer with less than six months of work at the plant (SMR 268 with 95% CI 172 to 399). CONCLUSIONS The importance of the cohort lies with the pure amosite exposure which took place in the plant and the extended period of latency which has followed. The death certificate analysis indicates the pathogenicity of amosite, the predominant commercial amphibole used in the United States. These data confirm a link between amosite asbestos and respiratory malignancy as well as mesothelioma.
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Affiliation(s)
- J L Levin
- Department of Occupational and Environmental Medicine, University of Texas Health Center 75710, USA
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46
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Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, that encompasses 250 kb of genomic DNA, cause cystic fibrosis. More than 5-10% of CF patients in most populations studied carry undefined mutations and hence intragenic CA repeats are important tools in genetic counselling. To date, polymorphic intragenic repeats have been found in introns 6a, 8 and 17b. We have identified a novel CA repeat within intron 1 of the CFTR gene that lies about 70 kb 5' to intron 6a and so will be a useful additional diagnostic marker.
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Affiliation(s)
- D S Moulin
- Institute of Molecular Medicine, Oxford University, John Radcliffe Hospital, UK
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Madurai S, Moodley D, Coovadia HM, Gopaul W, Smith AN, York DF. Infant-maternal HIV-specific immunoglobulin G1 antibody ratios as an indicator of vertical transmission. AIDS 1997; 11:1191-3. [PMID: 9233473 DOI: 10.1097/00002030-199709000-00021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Abstract
The choice of scanning protocol in CT will affect the dose delivered to the patient. A nationwide survey of CT operators was carried out in Australia in 1994 to determine the variation in routine head CT protocols. Only 29% of respondents used the supraorbitomeatal (SOM) baseline and thus avoided scanning the eyes. At 74% of sites, the routine protocol included scans both before and after injection of contrast. However, the post-contrast protocol differed from that used in the pre-contrast series in a number of cases. Where 5 mm thick slices were used, the mAs was 16% higher than for 10 mm thick slices. Increased awareness of the influence of baseline, slice thickness/spacing and accompanying exposure factors on patient dose may lead to greater standardization of head CT scanning protocols.
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Affiliation(s)
- A N Smith
- Faculty of Medicine and Health Sciences, University of Newcastle, Australia
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49
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Abstract
Bile duct brushings (BDB) are the method of choice for pathological diagnosis of malignancy of the hepatobiliary system in our institution. We examined results of the cytological assessment of 267 BDB and compared them with biopsies, which were available in 131 cases. Sensitivity of BDB for diagnosis of malignancy was 44% and specificity 100%, in keeping with the experience of others. The review of "false-negative cases" reveals four main reasons for the relatively modest sensitivity of BDB in diagnosis of malignancy: poor sampling, lack of diagnostic criteria for dysplasia-carcinoma in situ, difficulties in recognition of special tumor types, and underestimating the significance of the smear background. After a critical review and with regard to these issues, the sensitivity of BDB in our series could have been improved to 78%. We conclude that BDB can give a confident and definitive diagnosis of malignancy, which can be relied upon without a tissue biopsy. A negative result does not exclude malignancy.
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Affiliation(s)
- G Kocjan
- Department of Histopathology, University College London Medical School, United Kingdom
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50
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Abstract
Studies of rectal sensory thresholds and compliance in patients with the irritable bowel syndrome have produced conflicting results though there is persistent evidence of rectal hypersensitivity particularly in those with diarrhoea-predominant symptoms. This study examined rectal sensation and compliance in 31 patients with constipation-predominant irritable bowel syndrome (mean age 41 years, 27 female) and 17 healthy volunteers (mean age 45 years, 17 female). A rectal balloon was inflated with fluid at a constant rate and the volume and intrarectal pressure at sensory threshold was recorded. The volumes at first (129 +/- 8 vs 229 +/- 24 ml, P < 0.001 Mann-Whitney-U test), constant (159 +/- 12 vs 286 +/- 21, P < 0.001) and maximum tolerated sensation (290 +/- 13 vs 509 +/- 19, P < 0.001) were all significantly less in the irritable bowel group. There was no significant difference in intrarectal pressures at any of these volumes (29.0 +/- 2.2 cmH2O vs 29.0 +/- 2.5, 35.0 +/- 2.5 vs 34.0 +/- 2.8, 71 +/- 2.5 vs 65.0 +/- 3.0 respectively). Rectal compliance was significantly less in the irritable bowel group (3.6 +/- 0.2 ml/cmH2O vs 8.7 +/- 0.4, P < 0.001). Twenty two patients complained of abdominal pain on balloon inflation, mimicking that experienced as part of their symptoms. Patients with constipation-predominant irritable bowel syndrome have rectal hypersensitivity and reduced compliance.
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Affiliation(s)
- B J Slater
- Department of Surgery, University of Newcastle upon Tyne, UK
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