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Bradley JM, Bugg Z, Sackey A, Andrews SC, Wilson MT, Svistunenko DA, Moore GR, Le Brun NE. The Ferroxidase Centre of Escherichia coli Bacterioferritin Plays a Key Role in the Reductive Mobilisation of the Mineral Iron Core. Angew Chem Int Ed Engl 2024; 63:e202401379. [PMID: 38407997 DOI: 10.1002/anie.202401379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 02/28/2024]
Abstract
Ferritins are multimeric cage-forming proteins that play a crucial role in cellular iron homeostasis. All H-chain-type ferritins harbour a diiron site, the ferroxidase centre, at the centre of a 4 α-helical bundle, but bacterioferritins are unique in also binding 12 hemes per 24 meric assembly. The ferroxidase centre is known to be required for the rapid oxidation of Fe2+ during deposition of an immobilised ferric mineral core within the protein's hollow interior. In contrast, the heme of bacterioferritin is required for the efficient reduction of the mineral core during iron release, but has little effect on the rate of either oxidation or mineralisation of iron. Thus, the current view is that these two cofactors function in iron uptake and release, respectively, with no functional overlap. However, rapid electron transfer between the heme and ferroxidase centre of bacterioferritin from Escherichia coli was recently demonstrated, suggesting that the two cofactors may be functionally connected. Here we report absorbance and (magnetic) circular dichroism spectroscopies, together with in vitro assays of iron-release kinetics, which demonstrate that the ferroxidase centre plays an important role in the reductive mobilisation of the bacterioferritin mineral core, which is dependent on the heme-ferroxidase centre electron transfer pathway.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Zinnia Bugg
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Aaren Sackey
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Simon C Andrews
- School of Biological Sciences, University of Reading, Whiteknights, Reading, RG6 6AS, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
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2
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Bradley JM, Hutchings M, Arden MA, O'Cathain A, Maguire C, Wildman MJ. A RCT to explore the effectiveness of supporting adherence to nebuliser medication in adults with cystic fibrosis: fidelity assessment of study interventions. BMC Pulm Med 2024; 24:148. [PMID: 38509494 PMCID: PMC10956306 DOI: 10.1186/s12890-024-02923-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/22/2024] [Indexed: 03/22/2024] Open
Abstract
BACKGROUND A multi-component self-management intervention 'CFHealthHub' was developed to reduce pulmonary exacerbations in adults with Cystic Fibrosis (CF) by supporting adherence to nebuliser medication. It was evaluated in a randomized controlled trial (RCT) involving 19 CF centres, with 32 interventionists, 305 participants in the intervention group, and 303 participants in the standard care arm. Ensuring treatment fidelity of intervention delivery was crucial to ensure that the intervention produced the expected outcomes. METHODS Fidelity of the CFHealthHub intervention and standard care was assessed using different methods for each of the five fidelity domains defined by the Borrelli framework: study design, training, treatment delivery, receipt, and enactment. Study design ensured that the groups received the intended intervention or standard care. Interventionists underwent training and competency assessments to be deemed certified to deliver the intervention. Audio-recorded intervention sessions were assessed for fidelity drift. Receipt was assessed by identifying whether participants set Action and Coping Plans, while enactment was assessed using click analytics on the CFHealthHub digital platform. RESULTS Design: There was reasonable agreement (74%, 226/305) between the expected versus actual intervention dose received by participants in the CFHealthHub intervention group. The standard care group did not include focused adherence support for most centres and participants. Training: All interventionists were trained. Treatment delivery: The trial demonstrated good fidelity (overall fidelity by centre ranged from 79 to 97%), with only one centre falling below the mean threshold (> 80%) on fidelity drift assessments. Receipt: Among participants who completed the 12-month intervention, 77% (205/265) completed at least one action plan, and 60% (160/265) completed at least one coping plan. Enactment: 88% (268/305) of participants used web/app click analytics outside the intervention sessions. The mean (SD) number of web/app click analytics per participant was 31.2 (58.9). Additionally, 64% (195/305) of participants agreed to receive notifications via the mobile application, with an average of 53.6 (14.9) notifications per participant. CONCLUSIONS The study demonstrates high fidelity throughout the RCT, and the CFHealthHub intervention was delivered as intended. This provides confidence that the results of the RCT are a valid reflection of the effectiveness of the CFHealthHub intervention compared to standard care. TRIAL REGISTRATION ISRCTN registry: ISRCTN55504164 (date of registration: 12/10/2017).
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Affiliation(s)
- J M Bradley
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, UK.
| | - M Hutchings
- Sheffield Adult Cystic Fibrosis Centre, Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK
| | - M A Arden
- Centre for Behavioural Science and Applied Psychology, Sheffield Hallam University, Collegiate Crescent, Sheffield, S10 2BQ, UK
| | - A O'Cathain
- School of Health and Related Research, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - C Maguire
- Clinical Trials Research Unit, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - M J Wildman
- Sheffield Adult Cystic Fibrosis Centre, Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK
- School of Health and Related Research, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
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3
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Jenner LP, Crack JC, Kurth JM, Soldánová Z, Brandt L, Sokol KP, Reisner E, Bradley JM, Dahl C, Cheesman MR, Butt JN. Reaction of Thiosulfate Dehydrogenase with a Substrate Mimic Induces Dissociation of the Cysteine Heme Ligand Giving Insights into the Mechanism of Oxidative Catalysis. J Am Chem Soc 2022; 144:18296-18304. [PMID: 36173876 PMCID: PMC9562282 DOI: 10.1021/jacs.2c06062] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Thiosulfate dehydrogenases are bacterial cytochromes
that contribute
to the oxidation of inorganic sulfur. The active sites of these enzymes
contain low-spin c-type heme with Cys–/His axial ligation. However, the reduction potentials of these hemes
are several hundred mV more negative than that of the thiosulfate/tetrathionate
couple (Em, +198 mV), making it difficult
to rationalize the thiosulfate oxidizing capability. Here, we describe
the reaction of Campylobacter jejuni thiosulfate dehydrogenase (TsdA) with sulfite, an analogue of thiosulfate.
The reaction leads to stoichiometric conversion of the active site
Cys to cysteinyl sulfonate (Cα-CH2-S-SO3–) such that the protein exists in a form
closely resembling a proposed intermediate in the pathway for thiosulfate
oxidation that carries a cysteinyl thiosulfate (Cα-CH2-S-SSO3–). The active
site heme in the stable sulfonated protein displays an Em approximately 200 mV more positive than the Cys–/His-ligated state. This can explain the thiosulfate
oxidizing activity of the enzyme and allows us to propose a catalytic
mechanism for thiosulfate oxidation. Substrate-driven release of the
Cys heme ligand allows that side chain to provide the site of substrate
binding and redox transformation; the neighboring heme then simply
provides a site for electron relay to an appropriate partner. This
chemistry is distinct from that displayed by the Cys-ligated hemes
found in gas-sensing hemoproteins and in enzymes such as the cytochromes
P450. Thus, a further class of thiolate-ligated hemes is proposed,
as exemplified by the TsdA centers that have evolved to catalyze the
controlled redox transformations of inorganic oxo anions of sulfur.
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Affiliation(s)
- Leon P Jenner
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Julia M Kurth
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Zuzana Soldánová
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Linda Brandt
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Katarzyna P Sokol
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Christiane Dahl
- Institut für Mikrobiologie & Biotechnologie, Friedrich Wilhelms Universität Bonn, D-53115Bonn, Germany
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
| | - Julea N Butt
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, NorwichNR4 7TJ, United Kingdom
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4
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Abstract
The thermal and chemical stability of 24mer ferritins has led to attempts to exploit their naturally occurring nanoscale (8 nm) internal cavities for biotechnological applications. An area of increasing interest is the encapsulation of molecules either for medical or biocatalysis applications. Encapsulation requires ferritin dissociation, typically induced using high temperature or acidic conditions (pH ≥ 2), which generally precludes the inclusion of fragile cargo such as proteins or peptide fragments. Here we demonstrate that minimizing salt concentration combined with adjusting the pH to ≤8.5 (i.e. low proton/metal ion concentration) reversibly shifts the naturally occurring equilibrium between dimeric and 24meric assemblies of Escherichia coli bacterioferritin (Bfr) in favour of the disassembled form. Interconversion between the different oligomeric forms of Bfr is sufficiently slow under these conditions to allow the use of size exclusion chromatography to obtain wild type protein in the purely dimeric and 24meric forms. This control over association state was exploited to bind heme at natural sites that are not accessible in the assembled protein. The potential for biotechnological applications was demonstrated by the encapsulation of a small, acidic [3Fe-4S] cluster-containing ferredoxin within the Bfr internal cavity. The capture of ∼4-6 negatively charged ferredoxin molecules per cage indicates that charge complementarity with the inner protein surface is not an essential determinant of successful encapsulation.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Elizabeth Gray
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Jake Richardson
- Bioimaging Facility, John Innes Centre, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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5
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Abstract
Ferritins are proteins forming 24meric rhombic dodecahedral cages that play a key role in iron storage and detoxification in all cell types. Their function requires the transport of Fe2+ from the exterior of the protein to buried di-iron catalytic sites, known as ferroxidase centres, where Fe2+ is oxidized to form Fe3+-oxo precursors of the ferritin mineral core. The route of iron transit through animal ferritins is well understood: the Fe2+ substrate enters the protein via channels at the threefold axes and conserved carboxylates on the inner surface of the protein cage have been shown to contribute to transient binding sites that guide Fe2+ to the ferroxidase centres. The routes of iron transit through prokaryotic ferritins are less well studied but for some, at least, there is evidence that channels at the twofold axes are the major route for Fe2+ uptake. SynFtn, isolated from the cyanobacterium Synechococcus CC9311, is an atypical prokaryotic ferritin that was recently shown to take up Fe2+ via its threefold channels. However, the transfer site carboxylate residues conserved in animal ferritins are absent, meaning that the route taken from the site of iron entry into SynFtn to the catalytic centre is yet to be defined. Here, we report the use of a combination of site-directed mutagenesis, absorbance-monitored activity assays and protein crystallography to probe the effect of substitution of two residues potentially involved in this pathway. Both Glu141 and Asp65 play a role in guiding the Fe2+ substrate to the ferroxidase centre. In the absence of Asp65, routes for Fe2+ to, and Fe3+ exit from, the ferroxidase centre are affected resulting in inefficient formation of the mineral core. These observations further define the iron transit route in what may be the first characterized example of a new class of ferritins peculiar to cyanobacteria.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Joshua Fair
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.,Centre for Molecular and Structural Biochemistry, School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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6
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2O 2 but Slowly with O 2. Angew Chem Weinheim Bergstr Ger 2021; 133:8442-8450. [PMID: 38529354 PMCID: PMC10962548 DOI: 10.1002/ange.202015964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 11/09/2022]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo-EcBfr, pre-loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di-Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2-unreactive di-Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Michael T. Wilson
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Martin Clémancey
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Geneviève Blondin
- Université Grenoble AlpesCNRS, CEA, IRIGLaboratoire de Chimie et Biologie des Métaux, UMR 524917 rue des Martyrs38000GrenobleFrance
| | - Justin M. Bradley
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Geoffrey R. Moore
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Nick E. Le Brun
- School of ChemistryUniversity of East AngliaNorwich Research Park NorwichNorfolkNR4 7TJUK
| | - Marina Lučić
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
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7
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Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA. Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H 2 O 2 but Slowly with O 2. Angew Chem Int Ed Engl 2021; 60:8361-8369. [PMID: 33482043 PMCID: PMC8049013 DOI: 10.1002/anie.202015964] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/05/2021] [Indexed: 01/08/2023]
Abstract
Both O2 and H2O2 can oxidize iron at the ferroxidase center (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV/Vis, EPR, and Mössbauer spectroscopies have been used to follow the reactions when apo‐EcBfr, pre‐loaded anaerobically with Fe2+, was exposed to O2 or H2O2. We show that O2 binds di‐Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di‐Fe2+ FC, at a rate circa 1000 faster than O2, ensuring an overall 1:4 stoichiometry of iron oxidation by O2. Initially formed Fe3+ can further react with H2O2 (producing protein bound radicals) but relaxes within seconds to an H2O2‐unreactive di‐Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2O2 rather than sequester iron.
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Affiliation(s)
- Jacob Pullin
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Martin Clémancey
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Geneviève Blondin
- Université Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, UMR 5249, 17 rue des Martyrs, 38000, Grenoble, France
| | - Justin M Bradley
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Geoffrey R Moore
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Nick E Le Brun
- School of Chemistry, University of East Anglia, Norwich Research Park Norwich, Norfolk, NR4 7TJ, UK
| | - Marina Lučić
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Jonathan A R Worrall
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
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8
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Pullin J, Bradley JM, Moore GR, Le Brun NE, Wilson MT, Svistunenko DA. Electron Transfer from Haem to the Di-Iron Ferroxidase Centre in Bacterioferritin. Angew Chem Weinheim Bergstr Ger 2021; 133:8457-8460. [PMID: 38505322 PMCID: PMC10946800 DOI: 10.1002/ange.202015965] [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] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/05/2021] [Indexed: 03/21/2024]
Abstract
The iron redox cycle in ferritins is not completely understood. Bacterioferritins are distinct from other ferritins in that they contain haem groups. It is acknowledged that the two iron motifs in bacterioferritins, the di-nuclear ferroxidase centre and the haem B group, play key roles in two opposing processes, iron sequestration and iron mobilisation, respectively, and the two redox processes are independent. Herein, we show that in Escherichia coli bacterioferritin, there is an electron transfer pathway from the haem to the ferroxidase centre suggesting a new role(s) haem might play in bacterioferritins.
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Affiliation(s)
- Jacob Pullin
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
| | - Justin M. Bradley
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNorfolkNR4 7TJUK
| | - Geoffrey R. Moore
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNorfolkNR4 7TJUK
| | - Nick E. Le Brun
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNorfolkNR4 7TJUK
| | - Michael T. Wilson
- School of Life SciencesUniversity of EssexWivenhoe ParkColchesterEssexCO4 3SQUK
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9
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Pullin J, Bradley JM, Moore GR, Le Brun NE, Wilson MT, Svistunenko DA. Electron Transfer from Haem to the Di-Iron Ferroxidase Centre in Bacterioferritin. Angew Chem Int Ed Engl 2021; 60:8376-8379. [PMID: 33460502 PMCID: PMC8048850 DOI: 10.1002/anie.202015965] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/05/2021] [Indexed: 12/14/2022]
Abstract
The iron redox cycle in ferritins is not completely understood. Bacterioferritins are distinct from other ferritins in that they contain haem groups. It is acknowledged that the two iron motifs in bacterioferritins, the di‐nuclear ferroxidase centre and the haem B group, play key roles in two opposing processes, iron sequestration and iron mobilisation, respectively, and the two redox processes are independent. Herein, we show that in Escherichia coli bacterioferritin, there is an electron transfer pathway from the haem to the ferroxidase centre suggesting a new role(s) haem might play in bacterioferritins.
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Affiliation(s)
- Jacob Pullin
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Justin M Bradley
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK
| | - Geoffrey R Moore
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK
| | - Nick E Le Brun
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
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10
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Bradley JM, Svistunenko DA, Wilson MT, Hemmings AM, Moore GR, Le Brun NE. Bacterial iron detoxification at the molecular level. J Biol Chem 2021; 295:17602-17623. [PMID: 33454001 PMCID: PMC7762939 DOI: 10.1074/jbc.rev120.007746] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/07/2020] [Indexed: 01/18/2023] Open
Abstract
Iron is an essential micronutrient, and, in the case of bacteria, its availability is commonly a growth-limiting factor. However, correct functioning of cells requires that the labile pool of chelatable "free" iron be tightly regulated. Correct metalation of proteins requiring iron as a cofactor demands that such a readily accessible source of iron exist, but overaccumulation results in an oxidative burden that, if unchecked, would lead to cell death. The toxicity of iron stems from its potential to catalyze formation of reactive oxygen species that, in addition to causing damage to biological molecules, can also lead to the formation of reactive nitrogen species. To avoid iron-mediated oxidative stress, bacteria utilize iron-dependent global regulators to sense the iron status of the cell and regulate the expression of proteins involved in the acquisition, storage, and efflux of iron accordingly. Here, we survey the current understanding of the structure and mechanism of the important members of each of these classes of protein. Diversity in the details of iron homeostasis mechanisms reflect the differing nutritional stresses resulting from the wide variety of ecological niches that bacteria inhabit. However, in this review, we seek to highlight the similarities of iron homeostasis between different bacteria, while acknowledging important variations. In this way, we hope to illustrate how bacteria have evolved common approaches to overcome the dual problems of the insolubility and potential toxicity of iron.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
| | | | - Michael T Wilson
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom; Centre for Molecular and Structural Biochemistry, School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich, United Kingdom.
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11
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Arden MA, Hutchings M, Whelan P, Drabble SJ, Beever D, Bradley JM, Hind D, Ainsworth J, Maguire C, Cantrill H, O'Cathain A, Wildman M. Development of an intervention to increase adherence to nebuliser treatment in adults with cystic fibrosis: CFHealthHub. Pilot Feasibility Stud 2021; 7:1. [PMID: 33390191 PMCID: PMC7780635 DOI: 10.1186/s40814-020-00739-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 11/30/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Cystic fibrosis (CF) is a life-limiting genetic condition in which daily therapies to maintain lung health are critical, yet treatment adherence is low. Previous interventions to increase adherence have been largely unsuccessful and this is likely due to a lack of focus on behavioural evidence and theory alongside input from people with CF. This intervention is based on a digital platform that collects and displays objective nebuliser adherence data. The purpose of this paper is to identify the specific components of an intervention to increase and maintain adherence to nebuliser treatments in adults with CF with a focus on reducing effort and treatment burden. METHODS Intervention development was informed by the Behaviour Change Wheel (BCW) and person-based approach (PBA). A multidisciplinary team conducted qualitative research to inform a needs analysis, selected, and refined intervention components and methods of delivery, mapped adherence-related barriers and facilitators, associated intervention functions and behaviour change techniques, and utilised iterative feedback to develop and refine content and processes. RESULTS Results indicated that people with CF need to understand their treatment, be able to monitor adherence, have treatment goals and feedback and confidence in their ability to adhere, have a treatment plan to develop habits for treatment, and be able to solve problems around treatment adherence. Behaviour change techniques were selected to address each of these needs and were incorporated into the digital intervention developed iteratively, alongside a manual and training for health professionals. Feedback from people with CF and clinicians helped to refine the intervention which could be tailored to individual patient needs. CONCLUSIONS The intervention development process is underpinned by a strong theoretical framework and evidence base and was developed by a multidisciplinary team with a range of skills and expertise integrated with substantial input from patients and clinicians. This multifaceted development strategy has ensured that the intervention is usable and acceptable to people with CF and clinicians, providing the best chance of success in supporting people with CF with different needs to increase and maintain their adherence. The intervention is being tested in a randomised controlled trial across 19 UK sites.
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Affiliation(s)
- M A Arden
- Centre for Behavioural Science and Applied Psychology, Sheffield Hallam University, 2.03a Heart of the Campus, Collegiate Crescent Campus, Sheffield, S10 2BQ, UK.
| | - M Hutchings
- Sheffield Adult Cystic Fibrosis Unit Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK
| | - P Whelan
- Health eResearch Centre-Farr Institute, Division of Imaging, Informatics and Data Sciences, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9GB, UK
| | - S J Drabble
- School of Health and Related Research, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - D Beever
- Clinical Trials Research Unit, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - J M Bradley
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - D Hind
- Clinical Trials Research Unit, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - J Ainsworth
- Health eResearch Centre-Farr Institute, Division of Imaging, Informatics and Data Sciences, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9GB, UK
| | - C Maguire
- Clinical Trials Research Unit, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - H Cantrill
- Clinical Trials Research Unit, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - A O'Cathain
- School of Health and Related Research, University of Sheffield, Regent Court, 30 Regent Street, Sheffield, S1 4DA, UK
| | - M Wildman
- Sheffield Adult Cystic Fibrosis Unit Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK
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12
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Bradley JM, Pullin J, Moore GR, Svistunenko DA, Hemmings AM, Le Brun NE. Routes of iron entry into, and exit from, the catalytic ferroxidase sites of the prokaryotic ferritin SynFtn. Dalton Trans 2020; 49:1545-1554. [DOI: 10.1039/c9dt03570b] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This work describes the identification of two residues, D137 and E62, that are critical for, respectively, the transport of Fe2+ into, and Fe3+ out of, the catalytic sites of a prokaryotic ferritin.
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Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich
- UK
| | - Jacob Pullin
- School of Biological Sciences
- University of Essex
- Colchester CO4 3SQ
- UK
| | - Geoffrey R. Moore
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich
- UK
| | | | - Andrew M. Hemmings
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich
- UK
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich
- UK
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13
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Pellicer Martinez MT, Crack JC, Stewart MYY, Bradley JM, Svistunenko DA, Johnston AWB, Cheesman MR, Todd JD, Le Brun NE. Mechanisms of iron- and O 2-sensing by the [4Fe-4S] cluster of the global iron regulator RirA. eLife 2019; 8:e47804. [PMID: 31526471 PMCID: PMC6748827 DOI: 10.7554/elife.47804] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 07/29/2019] [Indexed: 01/05/2023] Open
Abstract
RirA is a global regulator of iron homeostasis in Rhizobium and related α-proteobacteria. In its [4Fe-4S] cluster-bound form it represses iron uptake by binding to IRO Box sequences upstream of RirA-regulated genes. Under low iron and/or aerobic conditions, [4Fe-4S] RirA undergoes cluster conversion/degradation to apo-RirA, which can no longer bind IRO Box sequences. Here, we apply time-resolved mass spectrometry and electron paramagnetic resonance spectroscopy to determine how the RirA cluster senses iron and O2. The data indicate that the key iron-sensing step is the O2-independent, reversible dissociation of Fe2+ from [4Fe-4S]2+ to form [3Fe-4S]0. The dissociation constant for this process was determined as Kd = ~3 µM, which is consistent with the sensing of 'free' iron in the cytoplasm. O2-sensing occurs through enhanced cluster degradation under aerobic conditions, via O2-mediated oxidation of the [3Fe-4S]0 intermediate to form [3Fe-4S]1+. This work provides a detailed mechanistic/functional view of an iron-responsive regulator.
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Affiliation(s)
- Ma Teresa Pellicer Martinez
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Melissa YY Stewart
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | | | - Andrew WB Johnston
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
| | - Jonathan D Todd
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of ChemistryUniversity of East AngliaNorwichUnited Kingdom
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14
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Jenner LP, Kurth JM, van Helmont S, Sokol KP, Reisner E, Dahl C, Bradley JM, Butt JN, Cheesman MR. Heme ligation and redox chemistry in two bacterial thiosulfate dehydrogenase (TsdA) enzymes. J Biol Chem 2019; 294:18002-18014. [PMID: 31467084 PMCID: PMC6879331 DOI: 10.1074/jbc.ra119.010084] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/26/2019] [Indexed: 01/04/2023] Open
Abstract
Thiosulfate dehydrogenases (TsdAs) are bidirectional bacterial di-heme enzymes that catalyze the interconversion of tetrathionate and thiosulfate at measurable rates in both directions. In contrast to our knowledge of TsdA activities, information on the redox properties in the absence of substrates is rather scant. To address this deficit, we combined magnetic CD (MCD) spectroscopy and protein film electrochemistry (PFE) in a study to resolve heme ligation and redox chemistry in two representative TsdAs. We examined the TsdAs from Campylobacter jejuni, a microaerobic human pathogen, and from the purple sulfur bacterium Allochromatium vinosum. In these organisms, the enzyme functions as a tetrathionate reductase and a thiosulfate oxidase, respectively. The active site Heme 1 in both enzymes has His/Cys ligation in the ferric and ferrous states and the midpoint potentials (Em) of the corresponding redox transformations are similar, −185 mV versus standard hydrogen electrode (SHE). However, fundamental differences are observed in the properties of the second, electron transferring, Heme 2. In C. jejuni, TsdA Heme 2 has His/Met ligation and an Em of +172 mV. In A. vinosum TsdA, Heme 2 reduction triggers a switch from His/Lys ligation (Em, −129 mV) to His/Met (Em, +266 mV), but the rates of interconversion are such that His/Lys ligation would be retained during turnover. In summary, our findings have unambiguously assigned Em values to defined axial ligand sets in TsdAs, specified the rates of Heme 2 ligand exchange in the A. vinosum enzyme, and provided information relevant to describing their catalytic mechanism(s).
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Affiliation(s)
- Leon P Jenner
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Julia M Kurth
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich Wilhelms Universität Bonn, D-53115 Bonn, Germany
| | - Sebastian van Helmont
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich Wilhelms Universität Bonn, D-53115 Bonn, Germany
| | - Katarzyna P Sokol
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Erwin Reisner
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Christiane Dahl
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich Wilhelms Universität Bonn, D-53115 Bonn, Germany
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Julea N Butt
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Myles R Cheesman
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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15
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Bennett SP, Soriano-Laguna MJ, Bradley JM, Svistunenko DA, Richardson DJ, Gates AJ, Le Brun NE. NosL is a dedicated copper chaperone for assembly of the Cu Z center of nitrous oxide reductase. Chem Sci 2019; 10:4985-4993. [PMID: 31183047 PMCID: PMC6530538 DOI: 10.1039/c9sc01053j] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [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] [Received: 03/01/2019] [Accepted: 04/01/2019] [Indexed: 11/21/2022] Open
Abstract
Nitrous oxide reductase (N2OR) is the terminal enzyme of the denitrification pathway of soil bacteria that reduces the greenhouse gas nitrous oxide (N2O) to dinitrogen. In addition to a binuclear CuA site that functions in electron transfer, the active site of N2OR features a unique tetranuclear copper cluster bridged by inorganic sulfide, termed CuZ. In copper-limited environments, N2OR fails to function, resulting in truncation of denitrification and rising levels of N2O released by cells to the atmosphere, presenting a major environmental challenge. Here we report studies of nosL from Paracoccus denitrificans, which is part of the nos gene cluster, and encodes a putative copper binding protein. A Paracoccus denitrificans ΔnosL mutant strain had no denitrification phenotype under copper-sufficient conditions but failed to reduce N2O under copper-limited conditions. N2OR isolated from ΔnosL cells was found to be deficient in copper and to exhibit attenuated activity. UV-visible absorbance spectroscopy revealed that bands due to the CuA center were unaffected, while those corresponding to the CuZ center were significantly reduced in intensity. In vitro studies of a soluble form of NosL without its predicted membrane anchor showed that it binds one Cu(i) ion per protein with attomolar affinity, but does not bind Cu(ii). Together, the data demonstrate that NosL is a copper-binding protein specifically required for assembly of the CuZ center of N2OR, and thus represents the first characterised assembly factor for the CuZ active site of this key environmental enzyme, which is globally responsible for the destruction of a potent greenhouse gas.
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Affiliation(s)
- Sophie P Bennett
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
| | - Manuel J Soriano-Laguna
- Centre for Molecular and Structural Biochemistry , School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
| | - Dimitri A Svistunenko
- School of Biological Sciences , University of Essex , Wivenhoe Park , Colchester CO4 3SQ , UK
| | - David J Richardson
- Centre for Molecular and Structural Biochemistry , School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
| | - Andrew J Gates
- Centre for Molecular and Structural Biochemistry , School of Biological Sciences , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK .
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16
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Child SA, Bradley JM, Pukala TL, Svistunenko DA, Le Brun NE, Bell SG. Electron transfer ferredoxins with unusual cluster binding motifs support secondary metabolism in many bacteria. Chem Sci 2018; 9:7948-7957. [PMID: 30542550 PMCID: PMC6237146 DOI: 10.1039/c8sc01286e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [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] [Received: 03/20/2018] [Accepted: 08/21/2018] [Indexed: 01/06/2023] Open
Abstract
The proteins responsible for controlling electron transfer in bacterial secondary metabolism are not always known or characterised. Here we demonstrate that many bacteria contain a set of unfamiliar ferredoxin encoding genes which are associated with those of cytochrome P450 (CYP) monooxygenases and as such are involved in anabolic and catabolic metabolism. The model organism Mycobacterium marinum M contains eleven of these genes which encode [3Fe-4S] or [4Fe-4S] single cluster containing ferredoxins but which have unusual iron-sulfur cluster binding motif sequences, CXX?XXC(X) n CP, where '?' indicates a variable amino acid residue. Rather than a cysteine residue, which is highly conserved in [4Fe-4S] clusters, or alanine or glycine residues, which are common in [3Fe-4S] ferredoxins, these genes encode at this position histidine, asparagine, tyrosine, serine, threonine or phenylalanine. We have purified, characterised and reconstituted the activity of several of these CYP/electron transfer partner systems and show that all those examined contain a [3Fe-4S] cluster. Furthermore, the ferredoxin used and the identity of the variable motif residue in these proteins affects the functionality of the monooxygenase system and has a significant influence on the redox properties of the ferredoxins. Similar ferredoxin encoding genes were identified across Mycobacterium species, including in the pathogenic M. tuberculosis and M. ulcerans, as well as in a wide range of other bacteria such as Rhodococcus and Streptomyces. In the majority of instances these are associated with CYP genes. These ferredoxin systems are important in controlling electron transfer across bacterial secondary metabolite production processes which include antibiotic and pigment formation among others.
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Affiliation(s)
- Stella A Child
- Department of Chemistry , University of Adelaide , SA 5005 , Australia .
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK
| | - Tara L Pukala
- Department of Chemistry , University of Adelaide , SA 5005 , Australia .
| | - Dimitri A Svistunenko
- School of Biological Sciences , University of Essex , Wivenhoe Park , Colchester CO4 3SQ , UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry , School of Chemistry , University of East Anglia , Norwich Research Park , Norwich , NR4 7TJ , UK
| | - Stephen G Bell
- Department of Chemistry , University of Adelaide , SA 5005 , Australia .
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17
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Kay KL, Zhou L, Tenori L, Bradley JM, Singleton C, Kihlken MA, Ciofi-Baffoni S, Le Brun NE. Kinetic analysis of copper transfer from a chaperone to its target protein mediated by complex formation. Chem Commun (Camb) 2018; 53:1397-1400. [PMID: 28078344 DOI: 10.1039/c6cc08966f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chaperone proteins that traffic copper around the cell minimise its toxicity by maintaining it in a tightly bound form. The transfer of copper from chaperones to target proteins is promoted by complex formation, but the kinetic characteristics of transfer have yet to be demonstrated for any chaperone-target protein pair. Here we report studies of copper transfer between the Atx1-type chaperone CopZ from Bacillus subtilis and the soluble domains of its cognate P-type ATPase transporter, CopAab. Transfer of copper from CopZ to CopAab was found to occur rapidly, with a rate constant at 25 °C of ∼267 s-1, many orders of magnitude higher than that for Cu(i) dissociation from CopZ in the absence of CopAab. The data demonstrate that complex formation between CopZ and CopAab, evidence for which is provided by NMR and electrospray ionisation mass spectrometry, dramatically enhances the rate of Cu(i) dissociation from CopZ.
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Affiliation(s)
- Kristine L Kay
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Liang Zhou
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Leonardo Tenori
- Magnetic Resonance Center CERM and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Chloe Singleton
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Margaret A Kihlken
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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18
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O'Neill B, McDonough SM, Wilson JJ, Bradbury I, Hayes K, Kirk A, Kent L, Cosgrove D, Bradley JM, Tully MA. Comparing accelerometer, pedometer and a questionnaire for measuring physical activity in bronchiectasis: a validity and feasibility study? Respir Res 2017; 18:16. [PMID: 28088206 PMCID: PMC5237513 DOI: 10.1186/s12931-016-0497-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 12/21/2016] [Indexed: 11/21/2022] Open
Abstract
Background There are challenges for researchers and clinicians to select the most appropriate physical activity tool, and a balance between precision and feasibility is needed. Currently it is unclear which physical activity tool should be used to assess physical activity in Bronchiectasis. The aim of this research is to compare assessment methods (pedometer and IPAQ) to our criterion method (ActiGraph) for the measurement of physical activity dimensions in Bronchiectasis (BE), and to assess their feasibility and acceptability. Methods Patients in this analysis were enrolled in a cross-sectional study. The ActiGraph and pedometer were worn for seven consecutive days and the IPAQ was completed for the same period. Statistical analyses were performed using SPSS 20 (IBM). Descriptive statistics were used; the percentage agreement between ActiGraph and the other measures were calculated using limits of agreement. Feedback about the feasibility of the activity monitors and the IPAQ was obtained. Results There were 55 (22 male) data sets available. For step count there was no significant difference between the ActiGraph and Pedometer, however, total physical activity time (mins) as recorded by the ActiGraph was significantly higher than the pedometer (mean ± SD, 232 (75) vs. 63 (32)). Levels of agreement between the two devices was very good for step count (97% agreement); and variation in the levels of agreement were within accepted limits of ±2 standard deviations from the mean value. IPAQ reported more bouted- moderate - vigorous physical activity (MVPA) [mean, SD; 167(170) vs 6(9) mins/day], and significantly less sedentary time than ActiGraph [mean, SD; 362(115) vs 634(76) vmins/day]. There were low levels of agreement between the two tools (57% sedentary behaviour; 0% MVPA10+), with IPAQ under-reporting sedentary behaviour and over-reporting MVPA10+ compared to ActiGraph. The monitors were found to be feasible and acceptable by participants and researchers; while the IPAQ was accepta ble to use, most patients required assistance to complete it. Conclusions Accurate measurement of physical activity is feasible in BE and will be valuable for future trials of therapeutic interventions. ActiGraph or pedometer could be used to measure simple daily step counts, but ActiGraph was superior as it measured intensity of physical activity and was a more precise measure of time spent walking. The IPAQ does not appear to represent an accurate measure of physical activity in this population. Trial registration Clinical Trials Registration Number NCT01569009: Physical Activity in Bronchiectasis.
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Affiliation(s)
- B O'Neill
- Centre for Health and Rehabilitation Technologies, Institute for Nursing and Health Research, Ulster University, Newtownabbey, UK
| | - S M McDonough
- Centre for Health and Rehabilitation Technologies, Institute for Nursing and Health Research, Ulster University, Newtownabbey, UK.,UKCRC Centre of Excellence for Public Health (Northern Ireland), Belfast, UK
| | - J J Wilson
- UKCRC Centre of Excellence for Public Health (Northern Ireland), Belfast, UK.,Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | - I Bradbury
- Centre for Health and Rehabilitation Technologies, Institute for Nursing and Health Research, Ulster University, Newtownabbey, UK
| | - K Hayes
- Centre for Health and Rehabilitation Technologies, Institute for Nursing and Health Research, Ulster University, Newtownabbey, UK
| | - A Kirk
- School of Psychological Sciences and Health, University of Strathclyde, Glasgow, UK
| | - L Kent
- Northern Ireland Clinical Research Network, Respiratory Health, Belfast Health and Social Care Trust, Belfast, UK
| | - D Cosgrove
- Northern Ireland Clinical Research Network, Respiratory Health, Belfast Health and Social Care Trust, Belfast, UK
| | - J M Bradley
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, Belfast, UK.
| | - M A Tully
- UKCRC Centre of Excellence for Public Health (Northern Ireland), Belfast, UK.,Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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19
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Bradley JM, Svistunenko DA, Moore GR, Le Brun NE. Tyr25, Tyr58 and Trp133 ofEscherichia colibacterioferritin transfer electrons between iron in the central cavity and the ferroxidase centre. Metallomics 2017; 9:1421-1428. [DOI: 10.1039/c7mt00187h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tyr58 and Trp133 play key roles in the formation and decay of the Tyr25 radical species ofE. coliBFR.
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Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | | | - Geoffrey R. Moore
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
| | - Nick E. Le Brun
- Centre for Molecular and Structural Biochemistry
- School of Chemistry
- University of East Anglia
- Norwich Research Park
- Norwich
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20
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Greene LM, Royal KD, Bradley JM, Lascelles BDX, Johnson LR, Hawkins EC. Severity of Nasal Inflammatory Disease Questionnaire for Canine Idiopathic Rhinitis Control: Instrument Development and Initial Validity Evidence. J Vet Intern Med 2016; 31:134-141. [PMID: 28019044 PMCID: PMC5259640 DOI: 10.1111/jvim.14629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/04/2016] [Accepted: 11/08/2016] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Effective treatments are needed for idiopathic chronic rhinitis in dogs, but assessment of efficacy requires a practical, quantifiable method for assessing severity of disease. OBJECTIVES To develop and perform initial validity and reliability testing of an owner-completed questionnaire for assessing clinical signs and dog and owner quality of life (QOL) in canine chronic rhinitis. ANIMALS Twenty-two dogs with histopathologically confirmed chronic rhinitis and 72 healthy dogs. METHODS In this prospective study, an online questionnaire was created based on literature review and feedback from veterinarians, veterinary internists with respiratory expertise, and owners of dogs with rhinitis. Owners of affected dogs completed the questionnaire twice, 1 week apart, to test reliability. Healthy dogs were assessed once. Data were analyzed using the Rasch Rating Scale Model, and results were interpreted using Messick's framework for evaluating construct validity evidence. RESULTS Initial item generation resulted in 5 domains: nasal signs, paranasal signs, global rhinitis severity, and dog's and owner's QOL. A 25-item questionnaire was developed using 5-point Likert-type scales. No respondent found the questionnaire difficult to complete. Strong psychometric evidence was available to support the substantive, generalizability, content, and structural aspects of construct validity. Statistical differences were found between responses for affected and control dogs for all but 2 items. These items were eliminated, resulting in the 23-item Severity of Nasal Inflammatory Disease (SNIFLD) questionnaire. CONCLUSIONS AND CLINICAL IMPORTANCE The SNIFLD questionnaire provides a mechanism for repeated assessments of disease severity in dogs with chronic rhinitis.
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Affiliation(s)
- L M Greene
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
| | - K D Royal
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
| | - J M Bradley
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
| | - B D X Lascelles
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
| | - L R Johnson
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | - E C Hawkins
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
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O’Neill B, O’Shea OM, McDonough SM, McGarvey L, Bradbury I, Arden MA, Troosters T, Cosgrove D, McManus T, McDonnell TJ, Bradley JM. S33 Physical activity intervention versus pulmonary rehabilitation in copd: the lively copd project. Thorax 2016. [DOI: 10.1136/thoraxjnl-2016-209333.39] [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: 11/04/2022]
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McDowell K, Bradley JM, McAuley DF, Blackwood B, O’Neill B. S14 Patients’ perceptions of an exercise programme delivered following discharge from hospital after critical illness (the revive trial). Thorax 2016. [DOI: 10.1136/thoraxjnl-2016-209333.20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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23
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O’Neill K, Moran F, Bradbury I, Downey DG, Rendall J, Tunney MM, Elborn JS, Bradley JM. P95 Exploring the timing of Hypertonic Saline (HTS) and Airways Clearance Techniques (ACT) in Cystic Fibrosis (CF): a cross over study. Thorax 2016. [DOI: 10.1136/thoraxjnl-2016-209333.238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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24
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El Hajj MC, Ninh VK, El Hajj EC, Bradley JM, Gardner JD. Estrogen receptor antagonism exacerbates cardiac structural and functional remodeling in female rats. Am J Physiol Heart Circ Physiol 2016; 312:H98-H105. [PMID: 27769996 DOI: 10.1152/ajpheart.00348.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 10/04/2016] [Accepted: 10/17/2016] [Indexed: 12/24/2022]
Abstract
We have previously demonstrated the cardioprotective effects of ovarian hormones against adverse ventricular remodeling imposed by chronic volume overload. Here, we assess the estrogen receptor dependence of this cardioprotection. Four groups of female rats were studied: sham-operated (Sham), volume overloaded [aortocaval fistula (ACF)], Sham treated with estrogen receptor antagonist ICI 182,780 (Sham + ICI), and ACF treated with ICI. Cardiac function was assessed temporally using echocardiogram, and tissue samples were collected at 5 days and 6 wk postsurgery. All rats with volume overload had significantly increased cardiac output (96 ± 32 ml/min for ACF and 108 ± 11 ml/min for ACF + ICI vs. 31 ± 2 for Sham, P < 0.05). At 6 wk, volume overload induced significant left ventricular (LV) hypertrophy in both untreated and treated ACF groups. Both ACF groups developed significantly increased LV end-diastolic diameter (LVEDD), indicating LV dilatation, with the ACF + ICI group having the greatest increase (340%, relative to Sham). Ejection fraction was significantly reduced in the ACF + ICI group (23% reduction) at 6 wk postsurgery compared with untreated ACF (P < 0.05). Interstitial collagen staining was significantly reduced by volume overload, with estrogen receptor antagonism causing greater collagen loss at both 5 days and 6 wk postsurgery. Furthermore, volume overload induced a significant increase in LV wall stress only in rats treated with estrogen antagonist. These data indicate that estrogen receptor signaling is essential for sex hormone-dependent cardioprotection against adverse remodeling. The maintenance of myocardial extracellular matrix collagen appears to play a key role in this cardioprotection. NEW & NOTEWORTHY We assessed the estrogen receptor (ER) dependence of female-specific cardioprotection using a rat model of chronic volume-overload stress. ER antagonism worsened ventricular wall stress, ventricular dilation, and cardiac dysfunction induced by volume overload. Further, blocking ERs resulted in cardiac remodeling and functional changes similar to that previously found in ovariectomized rats.
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Affiliation(s)
- M C El Hajj
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - V K Ninh
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - E C El Hajj
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - J M Bradley
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - J D Gardner
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
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25
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Patterson JE, Bradley JM, Elborn JS. Airway clearance in bronchiectasis: a randomized crossover trial of active cycle of breathing techniques (incorporating postural drainage and vibration) versus test of incremental respiratory endurance. Chron Respir Dis 2016; 1:127-30. [PMID: 16281653 DOI: 10.1191/1479972304cd034oa] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [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: 11/05/2022] Open
Abstract
Objectives:The purpose of this study was to compare the efficacy of the test of incremental respiratory endurance (TIRE) with active cycle of breathing techniques (ACBT) [incorporating postural drainage (PD) and vibration] as methods of airway clearance in adults with bronchiectasis. Design:A randomized crossover study in which a single session of ACBT (incorporating PD and vibration) was compared to a single session of TIRE was carried out in 20 patients (14 female) with stable, productive bronchiectasis. Measurements:Weight of sputum (treatment plus 30 min) was the primary outcome measure recorded. Pre and post-treatment measures of lung function and SpO2 were also recorded. Results:All 20 patients were stable during the study period. Sputum weight expectorated during and 30 min post-ACBT (incorporating PD and vibration) treatment was significantly greater than the sputum weight expectorated during and 30 min post-TIRE treatment [mean difference 2.44 g (95% CI 0.43-4.45)]. Conclusion:ACBT (incorporating PD and vibration) is a more effective method of airway clearance in bronchiectasis than TIRE during single treatment sessions.
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Affiliation(s)
- J E Patterson
- School of Rehabilitation Sciences, University of Ulster at Jordanstown, Northern Ireland BT37 0QB, UK
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26
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O'Neill B, Bradley JM, McKevitt AM, Heaney L, Riley M, McGovern V, MacMahon J. Prescribing practice for intermittent oxygen therapy: a GP survey. Chron Respir Dis 2016; 1:139-42. [PMID: 16281655 DOI: 10.1191/1479972304cd036oa] [Citation(s) in RCA: 1] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Introduction:UK figures show that the prescription of home oxygen cylinders for intermittent use is substantial. Aim: To examine GP assessment criteria and prescribing practice for intermittent oxygen therapy in patients with a diagnosis of chronic obstructive pulmonary disease (COPD) in Northern Ireland. Methods:A postal questionnaire was sent to all GPs (n = 534) in two health boards who had prescribed cylinder oxygen in a six month period prior to the study. The questionnaire was piloted to establish reliability and validity. Results:Completed questionnaires were returned by 52% (280/534) of GPs. GPs ‘most frequently’ used advice from hospital specialists [82% (230/280)] to determine the need for intermittent oxygen. Criteria such as breathlessness score on exercise (e.g., BORG), oximetry on exercise, local guidelines or national guidelines were used less frequently or never. Conclusions:Most patients are likely to have been prescribed intermittent oxygen without any objective assessment. Implementation of evidence-based guidelines and a formal oxygen assessment service, would rationalize the use of intermittent oxygen therapy and enable better targeting of this expensive resource.
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Affiliation(s)
- B O'Neill
- School of Rehabilitation Sciences, University of Ulster and Regional Respiratory Centre, Belfast City Hospital, Belfast, UK
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27
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Girvan HM, Bradley JM, Cheesman MR, Kincaid JR, Liu Y, Czarnecki K, Fisher K, Leys D, Rigby SEJ, Munro AW. Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex. Biochemistry 2016; 55:5073-83. [DOI: 10.1021/acs.biochem.6b00204] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hazel M. Girvan
- Centre
for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM),
Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Justin M. Bradley
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Myles R. Cheesman
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - James R. Kincaid
- Department
of Chemistry, Marquette University, 535 North 14th Street, Milwaukee, Wisconsin 53233, United States
| | - Yilin Liu
- Department
of Chemistry, Marquette University, 535 North 14th Street, Milwaukee, Wisconsin 53233, United States
| | - Kazimierz Czarnecki
- Department
of Chemistry, Marquette University, 535 North 14th Street, Milwaukee, Wisconsin 53233, United States
| | - Karl Fisher
- Centre
for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM),
Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - David Leys
- Centre
for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM),
Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Stephen E. J. Rigby
- Centre
for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM),
Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Andrew W. Munro
- Centre
for Synthetic Biology of Fine and Specialty Chemicals (SYNBIOCHEM),
Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
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Abstract
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe2+ to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.
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Affiliation(s)
- Justin M Bradley
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Nick E Le Brun
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Geoffrey R Moore
- Center for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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29
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Bradley JM, Svistunenko DA, Lawson TL, Hemmings AM, Moore GR, Le Brun NE. Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin. Angew Chem Int Ed Engl 2015; 54:14763-7. [PMID: 26474305 PMCID: PMC4691338 DOI: 10.1002/anie.201507486] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/17/2015] [Indexed: 12/20/2022]
Abstract
Ferritins are iron storage proteins that overcome the problems of toxicity and poor bioavailability of iron by catalyzing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di-Fe(3+) site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe(3+) into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe(2+) oxidation in the cavity. Herein, we demonstrate that EcBFR mineralization depends on three aromatic residues near the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe(2+) oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Dimitri A Svistunenko
- School of Biological Sciences, University of EssexWivenhoe Park, Colchester CO4 3SQ (UK)
| | - Tamara L Lawson
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
- School of Biological SciencesNorwich Research ParkUniversity of East AngliaNorwich NR4 7TJ (UK)
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East AngliaNorwich Research Park, Norwich, NR4 7TJ (UK) E-mail:
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30
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Bradley JM, Svistunenko DA, Lawson TL, Hemmings AM, Moore GR, Le Brun NE. Three Aromatic Residues are Required for Electron Transfer during Iron Mineralization in Bacterioferritin. ACTA ACUST UNITED AC 2015; 127:14976-14980. [PMID: 27478271 PMCID: PMC4954121 DOI: 10.1002/ange.201507486] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/17/2015] [Indexed: 11/29/2022]
Abstract
Ferritins are iron storage proteins that overcome the problems of toxicity and poor bioavailability of iron by catalyzing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di‐Fe3+ site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe3+ into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe2+ oxidation in the cavity. Herein, we demonstrate that EcBFR mineralization depends on three aromatic residues near the diiron site, Tyr25, Tyr58, and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe2+ oxidation in the BFR cavity, to the di‐ferric catalytic site for safe reduction of O2.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
| | - Dimitri A Svistunenko
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (UK)
| | - Tamara L Lawson
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
| | - Andrew M Hemmings
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK); School of Biological Sciences, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ (UK)
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ (UK)
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31
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Pfaffen S, Bradley JM, Abdulqadir R, Firme MR, Moore GR, Le Brun NE, Murphy MEP. A Diatom Ferritin Optimized for Iron Oxidation but Not Iron Storage. J Biol Chem 2015; 290:28416-28427. [PMID: 26396187 PMCID: PMC4653698 DOI: 10.1074/jbc.m115.669713] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 12/30/2022] Open
Abstract
Ferritin from the marine pennate diatom Pseudo-nitzschia multiseries (PmFTN) plays a key role in sustaining growth in iron-limited ocean environments. The di-iron catalytic ferroxidase center of PmFTN (sites A and B) has a nearby third iron site (site C) in an arrangement typically observed in prokaryotic ferritins. Here we demonstrate that Glu-44, a site C ligand, and Glu-130, a residue that bridges iron bound at sites B and C, limit the rate of post-oxidation reorganization of iron coordination and the rate at which Fe(3+) exits the ferroxidase center for storage within the mineral core. The latter, in particular, severely limits the overall rate of iron mineralization. Thus, the diatom ferritin is optimized for initial Fe(2+) oxidation but not for mineralization, pointing to a role for this protein in buffering iron availability and facilitating iron-sparing rather than only long-term iron storage.
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Affiliation(s)
- Stephanie Pfaffen
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Raz Abdulqadir
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Marlo R Firme
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Geoffrey R Moore
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom.
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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32
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Behera RK, Torres R, Tosha T, Bradley JM, Goulding CW, Theil EC. Fe(2+) substrate transport through ferritin protein cage ion channels influences enzyme activity and biomineralization. J Biol Inorg Chem 2015. [PMID: 26202907 DOI: 10.1007/s00775-015-1279-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ferritins, complex protein nanocages, form internal iron-oxy minerals (Fe2O3·H2O), by moving cytoplasmic Fe(2+) through intracage ion channels to cage-embedded enzyme (2Fe(2+)/O2 oxidoreductase) sites where ferritin biomineralization is initiated. The products of ferritin enzyme activity are diferric oxy complexes that are mineral precursors. Conserved, carboxylate amino acid side chains of D127 from each of three cage subunits project into ferritin ion channels near the interior ion channel exits and, thus, could direct Fe(2+) movement to the internal enzyme sites. Ferritin D127E was designed and analyzed to probe properties of ion channel size and carboxylate crowding near the internal ion channel opening. Glu side chains are chemically equivalent to, but longer by one -CH2 than Asp, side chains. Ferritin D127E assembled into normal protein cages, but diferric peroxo formation (enzyme activity) was not observed, when measured at 650 nm (DFP λ max). The caged biomineral formation, measured at 350 nm in the middle of the broad, nonspecific Fe(3+)-O absorption band, was slower. Structural differences (protein X-ray crystallography), between ion channels in wild type and ferritin D127E, which correlate with the inhibition of ferritin D127E enzyme activity include: (1) narrower interior ion channel openings/pores; (2) increased numbers of ion channel protein-metal binding sites, and (3) a change in ion channel electrostatics due to carboxylate crowding. The contributions of ion channel size and structure to ferritin activity reflect metal ion transport in ion channels are precisely regulated both in ferritin protein nanocages and membranes of living cells.
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Affiliation(s)
- Rabindra K Behera
- Children's Hospital Oakland Research Institute (CHORI), 5700 Martin Luther King Jr. Way, Oakland, CA, 94609, USA
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34
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Bradley JM, Moore GR, Le Brun NE. Mechanisms of iron mineralization in ferritins: one size does not fit all. J Biol Inorg Chem 2014; 19:775-85. [PMID: 24748222 DOI: 10.1007/s00775-014-1136-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 04/07/2014] [Indexed: 12/23/2022]
Abstract
Significant progress has been made in recent years toward understanding the processes by which an iron mineral is deposited within members of the ferritin family of 24mer iron storage proteins, enabled by high-resolution structures together with spectroscopic and kinetic studies. These suggest common characteristics that are shared between ferritins, namely, a highly symmetric arrangement of subunits that provides a protein coat around a central cavity in which the mineral is formed, channels through the coat that facilitate ingress and egress of ions, and catalytic sites, called ferroxidase centers, that drive Fe(2+) oxidation. They also reveal significant variations in both structure and mechanism amongst ferritins. Here, we describe three general types of structurally distinct ferroxidase center and the mechanisms of mineralization that they are associated with. The highlighted variation leads us to conclude that there is no universal mechanism by which ferritins function, but instead there exists several distinct mechanisms of ferritin iron mineralization.
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Affiliation(s)
- Justin M Bradley
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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35
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Hegarty BC, Bradley JM, Lappin MR, Balakrishnan N, Mascarelli PE, Breitschwerdt EB. Analysis of seroreactivity against cell culture-derived Bartonella spp. antigens in dogs. J Vet Intern Med 2013; 28:38-41. [PMID: 24341682 PMCID: PMC4895527 DOI: 10.1111/jvim.12263] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 10/02/2013] [Accepted: 10/28/2013] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Little is known about the specificity of Bartonella spp. immunofluorescent antibody (IFA) assays in dogs. Bacteremia in sick dogs most often has been associated with Bartonella henselae (Bh), Bartonella vinsonii subspecies berkhoffii (Bvb), and Bartonella koehlerae (Bk). Clarification of the diagnostic utility of IFA serology when testing against these organisms is needed. OBJECTIVE To evaluate the specificity of Bartonella IFA assays utilizing 6 cell culture-grown antigen preparations. ANIMALS Archived sera from SPF dogs (n = 29) and from dogs experimentally infected with Bvb (n = 10) and Bh (n = 3). METHODS Antibodies (Abs) to Bvb genotypes I, II, and III, Bh serotype I, strains H-1 and SA2, and to Bk were determined by IFA testing. RESULTS Serum from naïve SPF dogs shown to be negative for Bartonella bacteremia did not react with any of the 6 Bartonella antigens by IFA testing. Dogs experimentally infected with Bvb genotype I developed Abs against homologous antigens, with no cross-reactivity to heterologous Bvb genotypes, Bh H-1, SA2 strains, or to Bk. Dogs experimentally infected with Bh serotype I developed Abs against Bh H-1, but not to Bh SA2 strain with no cross-reactive Abs to Bvb genotypes I-III or to Bk. CONCLUSIONS AND CLINICAL IMPORTANCE Bartonella spp. Ab responses during acute experimental infections are species and type specific.
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Affiliation(s)
- B C Hegarty
- Intracellular Pathogens Research Laboratory, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, NCSU, Raleigh, NC
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36
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Kent L, Reix P, Innes JA, Zielen S, Le Bourgeois M, Braggion C, Lever S, Arets HGM, Brownlee K, Bradley JM, Bayfield K, O'Neill K, Savi D, Bilton D, Lindblad A, Davies JC, Sermet I, De Boeck K. Lung clearance index: evidence for use in clinical trials in cystic fibrosis. J Cyst Fibros 2013; 13:123-38. [PMID: 24315208 DOI: 10.1016/j.jcf.2013.09.005] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [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: 06/19/2013] [Revised: 09/10/2013] [Accepted: 09/23/2013] [Indexed: 02/09/2023]
Abstract
The ECFS-CTN Standardisation Committee has undertaken this review of lung clearance index as part of the group's work on evaluation of clinical endpoints with regard to their use in multicentre clinical trials in CF. The aims were 1) to review the literature on reliability, validity and responsiveness of LCI in patients with CF, 2) to gain consensus of the group on feasibility of LCI and 3) to gain consensus on answers to key questions regarding the promotion of LCI to surrogate endpoint status. It was concluded that LCI has an attractive feasibility and clinimetric properties profile and is particularly indicated for multicentre trials in young children with CF and patients with early or mild CF lung disease. This is the first article to collate the literature in this manner and support the use of LCI in clinical trials in CF.
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Affiliation(s)
- L Kent
- Centre for Health and Rehabilitation Technologies (CHaRT), Institute for Nursing and Health Research, University of Ulster, Newtownabbey, UK; Regional Cystic Fibrosis Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - P Reix
- Centre de Référence de la Mucoviscidose, Hospices Civils de Lyon, Lyon, France
| | - J A Innes
- Scottish Adult Cystic Fibrosis Service, Western General Hospital, Edinburgh, UK; Molecular and Clinical Medicine, University of Edinburgh, UK
| | - S Zielen
- Department of Paediatrics, J.W. Goethe-Universität Frankfurt, Germany
| | - M Le Bourgeois
- Centre de Référence de la Mucoviscidose, Hôpital Necker-Enfants Malades, Paris, France
| | - C Braggion
- Cystic Fibrosis Center, Pediatric Department, Meyer Children's Hospital, Florence, Italy
| | - S Lever
- Erasmus MC, Rotterdam, The Netherlands
| | - H G M Arets
- Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Center Utrecht, The Netherlands
| | - K Brownlee
- Children's Cystic Fibrosis Centre, Leeds Teaching Hospitals, Leeds, UK
| | - J M Bradley
- Centre for Health and Rehabilitation Technologies (CHaRT), Institute for Nursing and Health Research, University of Ulster, Newtownabbey, UK; Regional Cystic Fibrosis Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - K Bayfield
- Department of Gene Therapy, Imperial College London, UK
| | - K O'Neill
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK
| | - D Savi
- Department of Pediatrics and Pediatric Neurology, Cystic Fibrosis Center, Sapienza University of Rome, Italy
| | - D Bilton
- Royal Brompton & Harefield NHS Foundation Trust, London, UK
| | - A Lindblad
- Gothenburg CF Centre, Queen Silvia Children's Hospital, Göteborg, Sweden
| | - J C Davies
- Department of Gene Therapy, Imperial College London, UK; Royal Brompton & Harefield NHS Foundation Trust, London, UK
| | - I Sermet
- Centre de Référence de la Mucoviscidose, Hôpital Necker-Enfants Malades, Paris, France; Université Paris Descartes, Paris, France
| | - K De Boeck
- Pediatric Pulmonology, University Hospitals Leuven and KU Leuven, Leuven, Belgium.
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O'Neill K, Bradley JM, Bradbury I, Johnston E, Reid A, McCaughan J, Moore JE, Tunney MM, Elborn JS. S10 Lung Clearance Index (LCI) and Pseudomonous aeruginosa in adults and children with Cystic Fibrosis (CF). Thorax 2013. [DOI: 10.1136/thoraxjnl-2013-204457.16] [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: 11/04/2022]
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McCullough AR, Hughes CM, Tunney M, Elborn JS, Bradley JM. P181 Adherence to Treatment in Patients with Bronchiectasis Infected with Pseudomonas Aeruginosa. Thorax 2012. [DOI: 10.1136/thoraxjnl-2012-202678.242] [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: 11/03/2022]
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Bradley JM, Marritt SJ, Kihlken MA, Haynes K, Hemmings AM, Berks BC, Cheesman MR, Butt JN. Redox and chemical activities of the hemes in the sulfur oxidation pathway enzyme SoxAX. J Biol Chem 2012; 287:40350-9. [PMID: 23060437 DOI: 10.1074/jbc.m112.396192] [Citation(s) in RCA: 12] [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: 11/06/2022] Open
Abstract
BACKGROUND SoxAX enzymes initiate microbial oxidation of reduced inorganic sulfur compounds. Their catalytic mechanism is unknown. RESULTS Cyanide displaces the CysS(-) ligand to the active site heme following reduction by S(2)O(4)(2-) but not Eu(II). CONCLUSION An active site heme ligand becomes labile on exposure to substrate analogs. SIGNIFICANCE Elucidation of SoxAX mechanism is necessary to understand a widespread pathway for sulfur compound oxidation. SoxAX enzymes couple disulfide bond formation to the reduction of cytochrome c in the first step of the phylogenetically widespread Sox microbial sulfur oxidation pathway. Rhodovulum sulfidophilum SoxAX contains three hemes. An electrochemical cell compatible with magnetic circular dichroism at near infrared wavelengths has been developed to resolve redox and chemical properties of the SoxAX hemes. In combination with potentiometric titrations monitored by electronic absorbance and EPR, this method defines midpoint potentials (E(m)) at pH 7.0 of approximately +210, -340, and -400 mV for the His/Met, His/Cys(-), and active site His/CysS(-)-ligated heme, respectively. Exposing SoxAX to S(2)O(4)(2-), a substrate analog with E(m) ~-450 mV, but not Eu(II) complexed with diethylene triamine pentaacetic acid (E(m) ~-1140 mV), allows cyanide to displace the cysteine persulfide (CysS(-)) ligand to the active site heme. This provides the first evidence for the dissociation of CysS(-) that has been proposed as a key event in SoxAX catalysis.
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Affiliation(s)
- Justin M Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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Bui SH, McLean KJ, Cheesman MR, Bradley JM, Rigby SEJ, Levy CW, Leys D, Munro AW. Unusual spectroscopic and ligand binding properties of the cytochrome P450-flavodoxin fusion enzyme XplA. J Biol Chem 2012; 287:19699-714. [PMID: 22500029 PMCID: PMC3366004 DOI: 10.1074/jbc.m111.319202] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 04/05/2012] [Indexed: 11/06/2022] Open
Abstract
The Rhodococcus rhodochrous strain 11Y XplA enzyme is an unusual cytochrome P450-flavodoxin fusion enzyme that catalyzes reductive denitration of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX). We show by light scattering that XplA is a monomeric enzyme. XplA has high affinity for imidazole (K(d) = 1.6 μM), explaining previous reports of a red-shifted XplA Soret band in pure enzyme. The true Soret maximum of XplA is at 417 nm. Similarly, unusually weak XplA flavodoxin FMN binding (K(d) = 1.09 μM) necessitates its purification in the presence of the cofactor to produce hallmark flavin contributions absent in previously reported spectra. Structural and ligand-binding data reveal a constricted active site able to accommodate RDX and small inhibitory ligands (e.g. 4-phenylimidazole and morpholine) while discriminating against larger azole drugs. The crystal structure also identifies a high affinity imidazole binding site, consistent with its low K(d), and shows active site penetration by PEG, perhaps indicative of an evolutionary lipid-metabolizing function for XplA. EPR studies indicate heterogeneity in binding mode for RDX and other ligands. The substrate analog trinitrobenzene does not induce a substrate-like type I optical shift but creates a unique low spin EPR spectrum due to influence on structure around the distal water heme ligand. The substrate-free heme iron potential (-268 mV versus NHE) is positive for a low spin P450, and the elevated potential of the FMN semiquinone/hydroquinone couple (-172 mV) is also an adaptation that may reflect (along with the absence of a key Thr/Ser residue conserved in oxygen-activating P450s) the evolution of XplA as a specialized RDX reductase catalyst.
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Affiliation(s)
- Soi H. Bui
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Kirsty J. McLean
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Myles R. Cheesman
- the School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Justin M. Bradley
- the School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Stephen E. J. Rigby
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Colin W. Levy
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - David Leys
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Andrew W. Munro
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
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Bradley JM, Silkstone G, Wilson MT, Cheesman MR, Butt JN. Probing a Complex of Cytochrome c and Cardiolipin by Magnetic Circular Dichroism Spectroscopy: Implications for the Initial Events in Apoptosis. J Am Chem Soc 2011; 133:19676-9. [DOI: 10.1021/ja209144h] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Justin M. Bradley
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, U.K
| | - Gary Silkstone
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K
| | - Michael T. Wilson
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K
| | - Myles R. Cheesman
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, U.K
| | - Julea N. Butt
- Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, U.K
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Affiliation(s)
| | - Clark N. Taylor
- US Airforce Research Laboratory, Wright-Patterson Air Force Base, OH 45433
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Abstract
Background: Respiratory muscle strength is used diagnostically in clinical practice and as an outcome measure in clinical trials in various chronic lung diseases. There is limited data on its repeatability in people with non-CF bronchiectasis. The aim of the present study was to assess the repeatability of maximal inspiratory (P Imax) and expiratory pressures (PEmax) in a group of patients with stable, moderate-to-severe non-CF bronchiectasis. Methods: Twenty participants with stable moderate-to-severe non-CF bronchiectasis were recruited. Respiratory muscle strength measurements (three maximal inspiratory and expiratory pressures) were made on 2 separate days. A standard protocol was used, including practice tests, before obtaining three technically acceptable and reproducible readings with a difference of 10% or less between values. Clinical trial registration number: ClinicalTrials.gov: NCT00487149. Results: The mean (SD) age of the non-CF bronchiectasis group was 63 (9) years. Maximal inspiratory pressures were repeatable with mean (SD) for highest PImax, Test 1 and Test 2, 75.90 (20) and 79.40 (19) cmH2O, and limits of agreement (mean difference ± 2SD) —3.50 ± 20 cmH2O, (p = 0.14). Maximal expiratory pressures differed significantly with mean (SD) for highest PEmax, Test 1 and Test 2, 102.25 (27) and 112.30 (32) cmH 2O, and limits of agreement (mean difference ± 2SD) —10.10 ± 35 cmH2O, (p = 0.02). The intraclass correlation coefficient (95% CI) for highest PImax and PEmax was 0.93 (95% CI 0.82 to 0.97) and 0.90 (95% CI 0.76 to 0.96), respectively. Conclusion: Maximal inspiratory pressure measurements were repeatable during a period of clinical stability in moderate-to-severe non-CF bronchiectasis, suggesting this may be a useful outcome measure in non-CF bronchiectasis. Once a baseline has been established, a second visit is not required. PEmax was not a repeatable measure and further study is necessary to ascertain how much practice testing is required to obtain an accurate value.
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Affiliation(s)
- F. Moran
- University of Ulster, Newtownabbey, Northern Ireland,
| | - A. Piper
- University of Sydney, Sydney, Australia
| | - JS Elborn
- Centre for Infection and Immunity, Queens University, Belfast, Northern Ireland, Department of Respiratory Medicine, Belfast City Hospital, Belfast, Northern Ireland
| | - JM Bradley
- University of Ulster, Newtownabbey, Northern Ireland, Department of Respiratory Medicine, Belfast City Hospital, Belfast, Northern Ireland
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Hawkins EC, Clay LD, Bradley JM, Davidian M. Demographic and historical findings, including exposure to environmental tobacco smoke, in dogs with chronic cough. J Vet Intern Med 2010; 24:825-31. [PMID: 20492480 DOI: 10.1111/j.1939-1676.2010.0530.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [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] Open
Abstract
BACKGROUND Controlled studies investigating risk factors for the common presenting problem of chronic cough in dogs are lacking. HYPOTHESIS/OBJECTIVES To identify demographic and historical factors associated with chronic cough in dogs, and associations between the characteristics of cough and diagnosis. ANIMALS Dogs were patients of an academic internal medicine referral service. Coughing dogs had a duration of cough>or=2 months (n=115). Control dogs had presenting problems other than cough (n=104). METHODS Owners completed written questionnaires. Demographic information and diagnoses were obtained from medical records. Demographic and historical data were compared between coughing and control dogs. Demographic data and exposure to environmental tobacco smoke (ETS) also were compared with hospital accessions and adult smoking rates, respectively. Characteristics of cough were compared among diagnoses. RESULTS Most coughing dogs had a diagnosis of large airway disease (n=88; 77%). Tracheobronchomalacia (TBM) was diagnosed in 59 dogs (51%), including 79% of toy breed dogs. Demographic risk factors included older age, smaller body weight, and being toy breed (P<.001). No association was found between coughing and month (P=.239) or season (P=.414) of presentation. Exposure to ETS was not confirmed to be a risk factor (P=.243). No historical description of cough was unique to a particular diagnosis. CONCLUSIONS AND CLINICAL IMPORTANCE Associations with age, size, and toy breeds were strong. TBM is frequent in dogs with chronic cough, but descriptions of cough should be used cautiously in prioritizing differential diagnoses. The association between exposure to ETS and chronic cough deserves additional study.
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Affiliation(s)
- E C Hawkins
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
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Bradley JM, Thomson AJ, Inglis R, Milios CJ, Brechin EK, Piligkos S. MCD spectroscopy of hexanuclear Mn(iii) salicylaldoxime single-molecule magnets. Dalton Trans 2010; 39:9904-11. [DOI: 10.1039/c0dt00634c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
There should be a clear pathway through pulmonary rehabilitation and follow-on services. The aim of this survey was to determine the characteristics of the different components of the patient pathway, that is, pulmonary rehabilitation programs, ongoing exercise facilities, and support networks in Northern Ireland. Questionnaires were sent to current providers of pulmonary rehabilitation, providers of ongoing exercise, and support groups in Northern Ireland. Findings relating to the current status of pulmonary rehabilitation in Northern Ireland up to January 2007 are reported. There are currently 23 pulmonary rehabilitation programs in Northern Ireland. There appears to be a pathway through the short-term pulmonary rehabilitation program (6–8 weeks). Programs met standards for structure and format, except for the frequency of supervised exercise. Not all programs have links for the provision of ongoing exercise, but a range of exercise programs are available in leisure centers in Northern Ireland that include people with respiratory disease. There are 13 support groups for patients with respiratory disease in Northern Ireland and their function is diverse. Pulmonary rehabilitation is established in Northern Ireland, although not all patients are able to access these. Facilities for ongoing exercise and support groups are less developed. Improvements could be facilitated by better communication within the patient pathway and a strategic coordinated approach.
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Affiliation(s)
- B O’Neill
- Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, Co. Antrim, Northern Ireland
| | - JS Elborn
- Respiratory Medicine Research Group, Queens University Belfast
| | - J MacMahon
- Regional Respiratory Centre, Belfast Trust, City Hospital, Belfast, Northern Ireland
| | - JM Bradley
- Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, Co. Antrim, Northern Ireland; Regional Respiratory Centre, Belfast Trust, City Hospital, Belfast, Northern Ireland
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Bradley JM, Thomson AJ, McInnes EJL, Winpenny REP, Timco G. Magnetic circular dichroism spectroscopy of antiferromagnetically coupled hetero-metallic rings [H2NR2][Cr7MF8(O2CCMe3)16]. Dalton Trans 2008:3311-9. [DOI: 10.1039/b803269f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
BACKGROUND Non-invasive ventilation (NIV) may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis (CF). OBJECTIVES To compare the effect of NIV versus no NIV in people with CF. SEARCH STRATEGY We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials. Most recent search: October 2006. SELECTION CRITERIA Randomised controlled trials comparing a form of pressure preset or volume preset NIV to no NIV in people with acute or chronic respiratory failure in CF. DATA COLLECTION AND ANALYSIS Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data. MAIN RESULTS Fifteen trials were identified; seven trials met the inclusion criteria with a total of 106 participants. Six trials evaluated single treatment sessions only and one evaluated a six-week intervention. Four trials (79 participants) evaluated NIV for airway clearance compared with an alternative chest physiotherapy method and showed that airway clearance may be easier with NIV and people with CF may prefer it. We were unable to find any evidence that NIV increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated NIV for overnight ventilatory support. Lung function and nocturnal transcutaneous carbon dioxide were evaluated within two trials. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between NIV compared with oxygen or room air except for exercise performance, which significantly improved with NIV compared to room air over six weeks. AUTHORS' CONCLUSIONS Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with CF who have difficulty expectorating sputum. Non-invasive ventilation, when used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of NIV have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in CF airway clearance and exercise.
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Affiliation(s)
- F Moran
- University of Ulster, Room 14J07, School of Health Sciences, Shore Road, Newtownabbey, Northern Ireland, UK, BT37 0QB.
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Patterson JE, Hewitt O, Kent L, Bradbury I, Elborn JS, Bradley JM. Acapella versus 'usual airway clearance' during acute exacerbation in bronchiectasis: a randomized crossover trial. Chron Respir Dis 2007; 4:67-74. [PMID: 17621572 DOI: 10.1177/1479972306075483] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [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: 11/15/2022] Open
Abstract
Devices such as the Acapella may facilitate independent airway clearance, however, few clinical trials have investigated the efficacy of Acapella. The aim of this study was to compare the effectiveness of Acapella to 'usual airway clearance' in adults during an acute exacerbation of bronchiectasis requiring oral antibiotic therapy. Twenty patients with bronchiectasis and an acute exacerbation requiring oral antibiotic therapy were recruited into a randomized crossover trial. Patients were allocated to one of two groups determined by concealed computer generated randomization. Group 1 (n=10): airway clearance session using Acapella at home twice daily during oral antibiotic therapy. Group 2 (n=10): 'usual' airway clearance sessions at home during oral antibiotic therapy. Patients recorded duration of each treatment session, volume of sputum produced and perception of breathlessness. An independent assessor performed outcome measures of spirometric lung function, pulse oximetry and breathlessness at the beginning and end of the study period. The mean volume of sputum expectorated during Acapella sessions was greater than for usual airway clearance sessions although this difference was not significant 2.61 ml (95% CI-1.62 to 6.84). Mean duration of Acapella sessions was greater than usual airway clearance sessions and approached significance. There were no significant between group differences in changes in lung function. This study demonstrates that the Acapella device may offer an acceptable, user-friendly method of airway clearance in patients with bronchiectasis.
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Affiliation(s)
- J E Patterson
- Regional Respiratory Centre, Belfast City Hospital, and Physiotherapy, Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, Northern Ireland
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Abstract
BACKGROUND Predictive equations have been proposed as a simpler alternative to hypoxic challenge testing (HCT) for determining the risk of in-flight hypoxia. AIM To assess agreement between hypoxic challenge testing (HCT) and predictive equations for assessment of in-flight hypoxia. DESIGN Retrospective study. METHODS Patients with chronic obstructive pulmonary disease (COPD) (n = 15), interstitial lung disease (ILD) (n = 15) and cystic fibrosis (CF) (n = 15) were studied. Spirometry was recorded prior to hypoxic inhalation and oxygen saturations (SpO2) were recorded before, after and during hypoxic inhalation. Blood gases were analysed before and after hypoxic inhalation and when SpO2 = 85%. An HCT was performed using the Ventimask method. The PaO2 at altitude was estimated for each group using four published predictive equations, which use values of PaO2 (ground) and lung function measurements to predict altitude PaO2. Results were interpreted using the BTS recommendations for prescription of in-flight oxygen post HCT. The Stuart Maxwell test of overall homogeneity was used to assess agreement between HCT results and each of the predictive equations. RESULTS Ground PaO2 was significantly greater in patients with CF than either ILD or COPD (p < 0.05). PaO2 in all three groups significantly decreased following HCT. With the exception of equation 3, significantly fewer patients in each group would require in-flight O2 if prescription was based on HCT, compared to predictive equations (p < 0.05). DISCUSSION Predictive equations considerably overestimate the need for in-flight O2, compared to HCT.
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Affiliation(s)
- S E Martin
- Health and Rehabilitation Sciences Research Institute, School of Health Sciences, University of Ulster, UK
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