1
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Galloway JM, Aslam ZP, Yeandel SR, Kulak A, Ilett MA, Kim YY, Bejarano-Villafuerte A, Pokroy B, Drummond-Brydson RM, Freeman CL, Harding JH, Kapur N, Meldrum FC. Electron transparent nanotubes reveal crystallization pathways in confinement. Chem Sci 2023; 14:6705-6715. [PMID: 37350829 PMCID: PMC10283488 DOI: 10.1039/d3sc00869j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/13/2023] [Indexed: 06/24/2023] Open
Abstract
The cylindrical pores of track-etched membranes offer excellent environments for studying the effects of confinement on crystallization as the pore diameter is readily varied and the anisotropic morphologies can direct crystal orientation. However, the inability to image individual crystals in situ within the pores in this system has prevented many of the underlying mechanisms from being characterized. Here, we study the crystallization of calcium sulfate within track-etched membranes and reveal that oriented gypsum forms in 200 nm diameter pores, bassanite in 25-100 nm pores and anhydrite in 10 nm pores. The crystallization pathways are then studied by coating the membranes with an amorphous titania layer prior to mineralization to create electron transparent nanotubes that protect fragile precursor materials. By visualizing the evolutionary pathways of the crystals within the pores we show that the product single crystals derive from multiple nucleation events and that orientation is determined at early reaction times. Finally, the transformation of bassanite to gypsum within the membrane pores is studied using experiment and potential mean force calculations and is shown to proceed by localized dissolution/reprecipitation. This work provides insight into the effects of confinement on crystallization processes, which is relevant to mineral formation in many real-world environments.
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Affiliation(s)
| | - Zabeada P Aslam
- Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds Leeds LS2 9JT UK
| | - Stephen R Yeandel
- Department of Materials Science and Engineering Sir Robert Hadfield Building, Mappin Street Sheffield S1 3JD UK
| | | | - Martha A Ilett
- Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds Leeds LS2 9JT UK
| | - Yi-Yeoun Kim
- School of Chemistry, University of Leeds Leeds LS2 9JT UK
| | | | - Boaz Pokroy
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology Haifa 3200003 Israel
| | - Rik M Drummond-Brydson
- Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds Leeds LS2 9JT UK
| | - Colin L Freeman
- Department of Materials Science and Engineering Sir Robert Hadfield Building, Mappin Street Sheffield S1 3JD UK
| | - John H Harding
- Department of Materials Science and Engineering Sir Robert Hadfield Building, Mappin Street Sheffield S1 3JD UK
| | - Nikil Kapur
- School of Mechanical Engineering, University of Leeds Leeds LS2 9JT UK
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2
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Anderson MW, Bennett M, Cedeno R, Cölfen H, Cox SJ, Cruz-Cabeza AJ, De Yoreo JJ, Drummond-Brydson R, Dudek MK, Fichthorn KA, Finney AR, Ford I, Galloway JM, Gebauer D, Grossier R, Harding JH, Hare A, Horváth D, Hunter L, Kim J, Kimura Y, Kirschhock CEA, Kiselev AA, Kras W, Kuttner C, Lee AY, Liao Z, Maini L, Nilsson Lill SO, Pellens N, Price SL, Rietveld IB, Rimer JD, Roberts KJ, Rogal J, Salvalaglio M, Sandei I, Schuszter G, Sefcik J, Sun W, Ter Horst JH, Ukrainczyk M, Van Driessche AES, Veesler S, Vekilov PG, Verma V, Whale T, Wheatcroft HP, Zeglinski J. Understanding crystal nucleation mechanisms: where do we stand? General discussion. Faraday Discuss 2022; 235:219-272. [PMID: 35789238 DOI: 10.1039/d2fd90021a] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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3
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Radajewski D, Hunter L, He X, Nahi O, Galloway JM, Meldrum FC. An innovative data processing method for studying nanoparticle formation in droplet microfluidics using X-rays scattering. Lab Chip 2021; 21:4498-4506. [PMID: 34671784 DOI: 10.1039/d1lc00545f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
X-ray scattering techniques provide a powerful means of characterizing the formation of nanoparticles in solution. Coupling these techniques to segmented-flow microfluidic devices that offer well-defined environments gives access to in situ time-resolved analysis, excellent reproducibility, and eliminates potential radiation damage. However, analysis of the resulting datasets can be extremely time-consuming, where these comprise frames corresponding to the droplets alone, the continuous phase alone, and to both at their interface. We here describe a robust, low-cost, and versatile droplet microfluidics device and use it to study the formation of magnetite nanoparticles with simultaneous synchrotron SAXS and WAXS. Lateral outlet capillaries facilitate the X-ray analysis and reaction times of between a few seconds and minutes can be accommodated. A two-step data processing method is then described that exploits the unique WAXS signatures of the droplets, continuous phase, and interfacial region to identify the frames corresponding to the droplets. These are then sorted, and the background scattering is subtracted using an automated frame-by-frame approach, allowing the signal from the nanoparticles to be isolated from the raw data. Modeling these data gives quantitative information about the evolution of the sizes and structures of the nanoparticles, in agreement with TEM observations. This versatile platform can be readily employed to study a wide range of dynamic processes in heterogeneous systems.
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Affiliation(s)
- Dimitri Radajewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Liam Hunter
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Xuefeng He
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Ouassef Nahi
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Johanna M Galloway
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Fiona C Meldrum
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
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4
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Galloway JM, Bray HEV, Shoemark DK, Hodgson LR, Coombs J, Mantell JM, Rose RS, Ross JF, Morris C, Harniman RL, Wood CW, Arthur C, Verkade P, Woolfson DN. De Novo Designed Peptide and Protein Hairpins Self-Assemble into Sheets and Nanoparticles. Small 2021; 17:e2100472. [PMID: 33590708 DOI: 10.1002/smll.202100472] [Citation(s) in RCA: 12] [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] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Indexed: 06/12/2023]
Abstract
The design and assembly of peptide-based materials has advanced considerably, leading to a variety of fibrous, sheet, and nanoparticle structures. A remaining challenge is to account for and control different possible supramolecular outcomes accessible to the same or similar peptide building blocks. Here a de novo peptide system is presented that forms nanoparticles or sheets depending on the strategic placement of a "disulfide pin" between two elements of secondary structure that drive self-assembly. Specifically, homodimerizing and homotrimerizing de novo coiled-coil α-helices are joined with a flexible linker to generate a series of linear peptides. The helices are pinned back-to-back, constraining them as hairpins by a disulfide bond placed either proximal or distal to the linker. Computational modeling indicates, and advanced microscopy shows, that the proximally pinned hairpins self-assemble into nanoparticles, whereas the distally pinned constructs form sheets. These peptides can be made synthetically or recombinantly to allow both chemical modifications and the introduction of whole protein cargoes as required.
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Affiliation(s)
- Johanna M Galloway
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Harriet E V Bray
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Deborah K Shoemark
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Lorna R Hodgson
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio/Bristol Biodesign Institute, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Jennifer Coombs
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- Bristol Centre for Functional Nanomaterials, School of Physics, University of Bristol, HH Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - Judith M Mantell
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Ruth S Rose
- School of Biological and Chemical Sciences, Fogg Building, Queen Mary University of London, Mile End Road, London, E1 4QD, UK
| | - James F Ross
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Caroline Morris
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
- BrisSynBio/Bristol Biodesign Institute, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
- School of Chemistry, University of Glasgow, 0/1 125 Novar Drive, Glasgow, G12 9TA, UK
| | - Robert L Harniman
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Christopher W Wood
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
- BrisSynBio/Bristol Biodesign Institute, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
- School of Biological Sciences, Roger Land Building, King's Buildings, Edinburgh, EH9 3JQ, UK
| | - Christopher Arthur
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio/Bristol Biodesign Institute, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Derek N Woolfson
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK
- BrisSynBio/Bristol Biodesign Institute, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
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5
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Galloway JM, Senior L, Fletcher JM, Beesley JL, Hodgson LR, Harniman RL, Mantell JM, Coombs J, Rhys GG, Xue WF, Mosayebi M, Linden N, Liverpool TB, Curnow P, Verkade P, Woolfson DN. Bioinspired Silicification Reveals Structural Detail in Self-Assembled Peptide Cages. ACS Nano 2018; 12:1420-1432. [PMID: 29275624 PMCID: PMC5967840 DOI: 10.1021/acsnano.7b07785] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/24/2017] [Indexed: 05/25/2023]
Abstract
Understanding how molecules in self-assembled soft-matter nanostructures are organized is essential for improving the design of next-generation nanomaterials. Imaging these assemblies can be challenging and usually requires processing, e.g., staining or embedding, which can damage or obscure features. An alternative is to use bioinspired mineralization, mimicking how certain organisms use biomolecules to template mineral formation. Previously, we have reported the design and characterization of Self-Assembled peptide caGEs (SAGEs) formed from de novo peptide building blocks. In SAGEs, two complementary, 3-fold symmetric, peptide hubs combine to form a hexagonal lattice, which curves and closes to form SAGE nanoparticles. As hexagons alone cannot tile onto spheres, the network must also incorporate nonhexagonal shapes. While the hexagonal ultrastructure of the SAGEs has been imaged, these defects have not been observed. Here, we show that positively charged SAGEs biotemplate a thin, protective silica coating. Electron microscopy shows that these SiO2-SAGEs do not collapse, but maintain their 3D shape when dried. Atomic force microscopy reveals a network of hexagonal and irregular features on the SiO2-SAGE surface. The dimensions of these (7.2 nm ± 1.4 nm across, internal angles 119.8° ± 26.1°) are in accord with the designed SAGE network and with coarse-grained modeling of the SAGE assembly. The SiO2-SAGEs are permeable to small molecules (<2 nm), but not to larger biomolecules (>6 nm). Thus, bioinspired silicification offers a mild technique that preserves soft-matter nanoparticles for imaging, revealing structural details <10 nm in size, while also maintaining desirable properties, such as permeability to small molecules.
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Affiliation(s)
- Johanna M. Galloway
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
| | - Laura Senior
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
| | - Jordan M. Fletcher
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
| | - Joseph L. Beesley
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
| | - Lorna R. Hodgson
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
| | - Robert L. Harniman
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
| | - Judith M. Mantell
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- Wolfson
Bioimaging Facility, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
| | - Jennifer Coombs
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- Bristol
Centre for Functional Nanomaterials, NSQI, University of Bristol, Tyndall Avenue, Bristol, BS8 1FD, U.K.
| | - Guto G. Rhys
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
| | - Wei-Feng Xue
- School
of Biosciences, Stacy Building, University
of Kent, Canterbury, CT2 7NJ, U.K.
| | - Majid Mosayebi
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, U.K.
- School of
Mathematics, University of Bristol, University Walk, Bristol, BS8 1TW, U.K.
| | - Noah Linden
- School of
Mathematics, University of Bristol, University Walk, Bristol, BS8 1TW, U.K.
| | - Tanniemola B. Liverpool
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, U.K.
- School of
Mathematics, University of Bristol, University Walk, Bristol, BS8 1TW, U.K.
| | - Paul Curnow
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, U.K.
| | - Paul Verkade
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- Wolfson
Bioimaging Facility, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, U.K.
| | - Derek N. Woolfson
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, U.K.
- School
of Biochemistry, University of Bristol, Biomedical Sciences Building, University
Walk, Bristol, BS8 1TD, U.K.
- BrisSynBio, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, U.K.
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6
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Galloway JM, Bird SM, Talbot JE, Shepley PM, Bradley RC, El-Zubir O, Allwood DA, Leggett GJ, Miles JJ, Staniland SS, Critchley K. Nano- and micro-patterning biotemplated magnetic CoPt arrays. Nanoscale 2016; 8:11738-11747. [PMID: 27221982 DOI: 10.1039/c6nr03330j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Patterned thin-films of magnetic nanoparticles (MNPs) can be used to make: surfaces for manipulating and sorting cells, sensors, 2D spin-ices and high-density data storage devices. Conventional manufacture of patterned magnetic thin-films is not environmentally friendly because it uses high temperatures (hundreds of degrees Celsius) and high vacuum, which requires expensive specialised equipment. To tackle these issues, we have taken inspiration from nature to create environmentally friendly patterns of ferromagnetic CoPt using a biotemplating peptide under mild conditions and simple apparatus. Nano-patterning via interference lithography (IL) and micro-patterning using micro-contact printing (μCP) were used to create a peptide resistant mask onto a gold surface under ambient conditions. We redesigned a biotemplating peptide (CGSGKTHEIHSPLLHK) to self-assemble onto gold surfaces, and mineralised the patterns with CoPt at 18 °C in water. Ferromagnetic CoPt is biotemplated by the immobilised peptides, and the patterned MNPs maintain stable magnetic domains. This bioinspired study offers an ecological route towards developing biotemplated magnetic thin-films for use in applications such as sensing, cell manipulation and data storage.
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Affiliation(s)
- J M Galloway
- School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK and School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - S M Bird
- Department of Chemistry, University of Sheffield, Dainton Building, Brook Hill, S3 7HF, UK
| | - J E Talbot
- School of Computer Science, University of Manchester, Kilburn Building, Oxford Road, Manchester, M13 9PL, UK
| | - P M Shepley
- School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - R C Bradley
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Maplin Street, Sheffield, S1 3JD, UK
| | - O El-Zubir
- Department of Chemistry, University of Sheffield, Dainton Building, Brook Hill, S3 7HF, UK and School of Chemistry, University of Newcastle, Chemical Nanoscience Laboratories, Bedson Building, Newcastle Upon Tyne, NE1 7RU, UK
| | - D A Allwood
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Maplin Street, Sheffield, S1 3JD, UK
| | - G J Leggett
- Department of Chemistry, University of Sheffield, Dainton Building, Brook Hill, S3 7HF, UK
| | - J J Miles
- School of Computer Science, University of Manchester, Kilburn Building, Oxford Road, Manchester, M13 9PL, UK
| | - S S Staniland
- Department of Chemistry, University of Sheffield, Dainton Building, Brook Hill, S3 7HF, UK
| | - K Critchley
- School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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7
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Bird SM, Rawlings AE, Galloway JM, Staniland SS. Using a biomimetic membrane surface experiment to investigate the activity of the magnetite biomineralisation protein Mms6. RSC Adv 2016; 6:7356-7363. [PMID: 27019707 PMCID: PMC4786949 DOI: 10.1039/c5ra16469a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 01/04/2016] [Indexed: 12/13/2022] Open
Abstract
Using a surface-based mimic of a magnetosome interior, the biomineralisation protein Mms6 was found to be a more effective nucleator than binder of magnetite nanoparticles, and performs better than its C-terminal region alone.
Magnetotactic bacteria are able to synthesise precise nanoparticles of the iron oxide magnetite within their cells. These particles are formed in dedicated organelles termed magnetosomes. These lipid membrane compartments use a range of biomineralisation proteins to nucleate and regulate the magnetite crystallisation process. A key component is the membrane protein Mms6, which binds to iron ions and helps to control the formation of the inorganic core. We have previously used Mms6 on gold surfaces patterned with a self-assembled monolayer to successfully produce arrays of magnetic nanoparticles. Here we use this surface system as a mimic of the interior face of the magnetosome membrane to study differences between intact Mms6 and the acid-rich C-terminal peptide subregion of the Mms6 protein. When immobilised on surfaces, the peptide is unable to reproduce the particle size or homogeneity control exhibited by the full Mms6 protein in our experimental setup. Moreover, the peptide is unable to support anchoring of a dense array of nanoparticles to the surface. This system also allows us to deconvolute particle binding from particle nucleation, and shows that Mms6 particle binding is less efficient when supplied with preformed magnetite nanoparticles when compared to particles precipitated from solution in the presence of the surface immobilised Mms6. This suggests that Mms6 binds to iron ions rather than to magnetite surfaces in our system, and is perhaps a nucleating agent rather than a controller of magnetite crystal growth. The comparison between the peptide and the protein under identical experimental conditions indicates that the full length sequence is required to support the full function of Mms6 on surfaces.
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Affiliation(s)
- Scott M Bird
- University of Sheffield, Department of Chemistry, Dainton Building, Sheffield, S3 7HF, UK.
| | - Andrea E Rawlings
- University of Sheffield, Department of Chemistry, Dainton Building, Sheffield, S3 7HF, UK.
| | - Johanna M Galloway
- University of Bristol, School of Chemistry, Cantock's Close, Bristol, BS8 1TS, UK
| | - Sarah S Staniland
- University of Sheffield, Department of Chemistry, Dainton Building, Sheffield, S3 7HF, UK.
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8
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Bird SM, Galloway JM, Rawlings AE, Bramble JP, Staniland SS. Taking a hard line with biotemplating: cobalt-doped magnetite magnetic nanoparticle arrays. Nanoscale 2015; 7:7340-7351. [PMID: 25825205 DOI: 10.1039/c5nr00651a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Rapid advancements made in technology, and the drive towards miniaturisation, means that we require reliable, sustainable and cost effective methods of manufacturing a wide range of nanomaterials. In this bioinspired study, we take advantage of millions of years of evolution, and adapt a biomineralisation protein for surface patterning of biotemplated magnetic nanoparticles (MNPs). We employ soft-lithographic micro-contact printing to pattern a recombinant version of the biomineralisation protein Mms6 (derived from the magnetotactic bacterium Magnetospirillum magneticum AMB-1). The Mms6 attaches to gold surfaces via a cysteine residue introduced into the N-terminal region. The surface bound protein biotemplates highly uniform MNPs of magnetite onto patterned surfaces during an aqueous mineralisation reaction (with a mean diameter of 90 ± 15 nm). The simple addition of 6% cobalt to the mineralisation reaction maintains the uniformity in grain size (with a mean diameter of 84 ± 14 nm), and results in the production of MNPs with a much higher coercivity (increased from ≈ 156 Oe to ≈ 377 Oe). Biotemplating magnetic nanoparticles on patterned surfaces could form a novel, environmentally friendly route for the production of bit-patterned media, potentially the next generation of ultra-high density magnetic data storage devices. This is a simple method to fine-tune the magnetic hardness of the surface biotemplated MNPs, and could easily be adapted to biotemplate a wide range of different nanomaterials on surfaces to create a range of biologically templated devices.
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Affiliation(s)
- Scott M Bird
- University of Sheffield, Department of Chemistry, Dainton Building, Sheffield, S3 7HF, UK.
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9
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McMahon PB, Caldwell RR, Galloway JM, Valder JF, Hunt AG. Quality and age of shallow groundwater in the Bakken Formation production area, Williston Basin, Montana and North Dakota. Ground Water 2015; 53 Suppl 1:81-94. [PMID: 25392910 DOI: 10.1111/gwat.12296] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/16/2014] [Indexed: 06/04/2023]
Abstract
The quality and age of shallow groundwater in the Bakken Formation production area were characterized using data from 30 randomly distributed domestic wells screened in the upper Fort Union Formation. Comparison of inorganic and organic chemical concentrations to health based drinking-water standards, correlation analysis of concentrations with oil and gas well locations, and isotopic data give no indication that energy-development activities affected groundwater quality. It is important, however, to consider these results in the context of groundwater age. Most samples were recharged before the early 1950s and had 14C ages ranging from <1000 to >30,000 years. Thus, domestic wells may not be as well suited for detecting contamination associated with recent surface spills as shallower wells screened near the water table. Old groundwater could be contaminated directly by recent subsurface leaks from imperfectly cemented oil and gas wells, but horizontal groundwater velocities calculated from 14C ages imply that the contaminants would still be less than 0.5 km from their source. For the wells sampled in this study, the median distance to the nearest oil and gas well was 4.6 km. Because of the slow velocities, a long-term commitment to groundwater monitoring in the upper Fort Union Formation is needed to assess the effects of energy development on groundwater quality. In conjunction with that effort, monitoring could be done closer to energy-development activities to increase the likelihood of early detection of groundwater contamination if it did occur.
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10
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Galloway JM, Bird SM, Bramble JP, Critchley K, Staniland SS. Biotemplating Magnetic Nanoparticles on Patterned Surfaces for Potential Use in Data Storage. ACTA ACUST UNITED AC 2013. [DOI: 10.1557/opl.2013.828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTThin-films of magnetic nanoparticles (MNPs) with high coercivities are deposited onto surfaces for use in data storage applications. This usually requires specialist clean-room facilities, sputtering equipment and high temperatures to achieve the correct crystallographic phases. One possible cheaper and more environmentally friendly alternative could be to use biomolecules. Many biomineralization and biotemplating molecules have been identified that are able to template a wide range of technologically relevant materials using mild, aqueous chemistry under physiological reaction conditions. Here, we have designed a dual affinity peptide (DAP) sequence to template MNPs onto a surface. One end of the DAP has a high binding affinity for SiO2 and the other for MNPs of the L10 phase of CoPt, a high coercivity magnetic material. Images of the biomineralized substrates show that nanoparticles of CoPt are localized onto the areas that were functionalized with the biotemplating DAP. Magnetic force microscopy (MFM) plots of the biotemplated nanoparticles show that there is magnetic contrast on the patterned surface.
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11
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de Simone G, Devereux RB, Roman MJ, Chinali M, Barac A, Panza JA, Lee ET, Galloway JM, Howard BV. Does cardiovascular phenotype explain the association between diabetes and incident heart failure? The Strong Heart Study. Nutr Metab Cardiovasc Dis 2013; 23:285-291. [PMID: 21940153 PMCID: PMC3246029 DOI: 10.1016/j.numecd.2011.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2010] [Revised: 06/06/2011] [Accepted: 06/15/2011] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND AIMS Diabetes remains a predictor of incident heart failure (HF), independent of intercurrent myocardial infarction (MI) and concomitant risk factors. Initial cardiovascular (CV) characteristics, associated with incident heart failure (HF) might explain the association of diabetes with incident HF. METHODS AND RESULTS Participants to the 2nd Strong Heart Study exam, without prevalent HF or coronary heart disease, or glomerular filtration rate <30 mL/min/1.73 m(2), were analyzed (n = 2757, 1777 women, 1278 diabetic). Cox regression of incident HF (follow-up 8.91 ± 2.76 years) included incident MI censored as a competing risk event. Acute MI occurred in 96 diabetic (7%) and 84 non-diabetic participants (6%, p = ns). HF occurred in 156 diabetic (12%) and in 68 non-diabetic participants (5%; OR = 2.89, p < 0.001). After accounting for competing MI and controlling for age, gender, BMI, systolic blood pressure, smoking habit, plasma cholesterol, antihypertensive treatment, heart rate, fibrinogen and C-reactive protein, incident HF was predicted by greater LV mass index, larger left atrium, lower systolic function, greater left atrial systolic force and urinary albumin/creatinine excretion. Risk of HF was reduced with more rapid LV relaxation and anti-hypertensive therapy. Diabetes increases hazard of HF by 66% (0.02 < p < 0.001). The effect of diabetes could be explained by the level of HbA1c. CONCLUSIONS Incident HF occurs more frequently in diabetes, independent of intercurrent MI, abnormal LV geometry, subclinical systolic dysfunction and indicators of less rapid LV relaxation, and is influenced by poor metabolic control. Identification of CV phenotype at high-risk for HF in diabetes should be advised.
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Affiliation(s)
- G de Simone
- Weill Cornell Medical College, New York, NY, USA.
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12
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Galloway JM, Bramble JP, Rawlings AE, Burnell G, Evans SD, Staniland SS. Biotemplated magnetic nanoparticle arrays. Small 2012; 8:204-208. [PMID: 22052737 DOI: 10.1002/smll.201101627] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 10/18/2011] [Indexed: 05/31/2023]
Abstract
Immobilized biomineralizing protein Mms6 templates the formation of uniform magnetite nanoparticles in situ when selectively patterned onto a surface. Magnetic force microscopy shows that the stable magnetite particles maintain their magnetic orientation at room temperature, and may be exchange coupled. This precision-mixed biomimetic/soft-lithography methodology offers great potential for the future of nanodevice fabrication.
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Affiliation(s)
- Johanna M Galloway
- School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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13
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Galloway JM, Staniland SS. Protein and peptide biotemplated metal and metal oxide nanoparticles and their patterning onto surfaces. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31620j] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [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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14
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Galloway JM, Arakaki A, Masuda F, Tanaka T, Matsunaga T, Staniland SS. Magnetic bacterial protein Mms6 controls morphology, crystallinity and magnetism of cobalt-doped magnetite nanoparticles in vitro. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm12003d] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Abstract
OBJECTIVE To describe a case of procainamide-induced psychosis in an adult treated for atrial fibrillation. CASE SUMMARY A 45-year-old Native American woman developed acute psychosis within 72 hours of initiating procainamide for atrial fibrillation. Symptoms abated within 24 hours of discontinuing procainamide. Serum procainamide/N-acetylprocainamide concentrations were therapeutic throughout treatment. Sotalol was started without recurrence of symptoms. DISCUSSION Psychosis is a rare complication of treatment with procainamide, but the exact mechanism for this adverse event is not fully understood. Seven cases implicating procainamide as the cause of acute psychosis are reported in the literature. Cases of psychosis involving other antiarrhythmic agents have also been reported. CONCLUSIONS Healthcare personnel should be aware of this adverse event related to procainamide and other antiarrhythmic agents.
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Affiliation(s)
- E D Bizjak
- College of Pharmacy, The University of Arizona, Tucson 85721, USA
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16
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Abstract
Arrhythmogenic right ventricular (RV) dysplasia consists of a dilatation of the right ventricle with a reduction of RV ejection fraction with fibrofatty replacement of the RV myocardium in the face of a well-preserved left ventricular systolic function. Arrhythmogenic RV dysplasia, which is a cause of sudden unexpected death, has been reported from many geographic areas, including the United States, Europe, and the Far East. This case report presents the first case of arrhythmogenic RV dysplasia in an American Indian (Native American) patient.
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Affiliation(s)
- J M Galloway
- Division of Cardiology, University of Arizona Health Sciences Center, Tucson, USA
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Howard BV, Lee ET, Cowan LD, Devereux RB, Galloway JM, Go OT, Howard WJ, Rhoades ER, Robbins DC, Sievers ML, Welty TK. Rising tide of cardiovascular disease in American Indians. The Strong Heart Study. Circulation 1999; 99:2389-95. [PMID: 10318659 DOI: 10.1161/01.cir.99.18.2389] [Citation(s) in RCA: 292] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Although cardiovascular disease (CVD) used to be rare among American Indians, Indian Health Service data suggest that CVD mortality rates vary greatly among American Indian communities and appear to be increasing. The Strong Heart Study was initiated to investigate CVD and its risk factors in American Indians in 13 communities in Arizona, Oklahoma, and South/North Dakota. METHODS AND RESULTS A total of 4549 participants (1846 men and 2703 women 45 to 74 years old) who were seen at the baseline (1989 to 1991) examination were subjected to surveillance (average 4.2 years, 1991 to 1995), and 88% of those remaining alive underwent a second examination (1993 to 1995). The medical records of all participants were exhaustively reviewed to ascertain nonfatal cardiovascular events that occurred since the baseline examination or to definitively determine cause of death. CVD morbidity and mortality rates were higher in men than in women and were similar in the 3 geographic areas. Coronary heart disease (CHD) incidence rates among American Indian men and women were almost 2-fold higher than those in the Atherosclerosis Risk in Communities Study. Significant independent predictors of CVD in women were diabetes, age, obesity (inverse), LDL cholesterol, albuminuria, triglycerides, and hypertension. In men, diabetes, age, LDL cholesterol, albuminuria, and hypertension were independent predictors of CVD. CONCLUSIONS At present, CHD rates in American Indians exceed rates in other US populations and may more often be fatal. Unlike other ethnic groups, American Indians appear to have an increasing incidence of CHD, possibly related to the high prevalence of diabetes. In the general US population, the rising prevalence of obesity and diabetes may reverse the decline in CVD death rates. Therefore, aggressive programs to control diabetes and its risk factors are needed.
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Affiliation(s)
- B V Howard
- Medlantic Research Institute and Washington Hospital Center, Washington, DC, USA.
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18
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Ramamoorthy P, Johnson BJ, Wilkinson AR, Galloway JM, McCollum PT. Vascular surgical society of great britain and ireland: limb salvage in the octogenarian. Br J Surg 1999; 86:706. [PMID: 10361343 DOI: 10.1046/j.1365-2168.1999.0706b.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND: Critical limb ischaemia (CLI) presents a unique set of problems in the elderly patient. Foremost among these is the much greater likelihood of loss of independence and reduced quality of life if major amputation is required. For this reason it has been this unit's policy to attempt reconstructive vascular surgery in almost all cases of CLI. The outcome of this policy was examined. METHODS: All patients had surgery performed under one consultant and data were entered prospectively on to a database. RESULTS: Risk factors included diabetes (17 per cent), smoking (78 per cent) and ischaemic heart disease (31 per cent). Some 127 patients had either femoropopliteal (59), femorodistal (64) or popliteal-distal grafts (four) performed for limb-threatening ischaemia. Follow-up was performed at 3, 6 and 12 months and then at annual intervals until death. Seventeen of these patients required a subsequent major amputation, 12 at the below-knee and five at the above-knee level. Mean follow-up was 2 years. The perioperative mortality rate was 15 per cent, although eight of these patients were admitted with acute or chronic ischaemia. Cumulative graft secondary patency rate was 68 per cent at 4 years for vein grafts. Some 95 per cent of patients with patent grafts were independently mobile. CONCLUSION: Excellent results can be achieved for limb salvage with a relatively low morbidity in this group. Elderly patients with CLI do not live long and avoidance of amputation is particularly desirable in order to maximize the quality of their remaining life.
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Curley PJ, Norrie L, Nicholson A, Galloway JM, Wilkinson AR. Accuracy of carotid duplex is laboratory specific and must be determined by internal audit. Eur J Vasc Endovasc Surg 1998; 15:511-4. [PMID: 9659886 DOI: 10.1016/s1078-5884(98)80111-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To assess the accuracy of carotid duplex in a single vascular laboratory at the prediction of an angiographic 70% internal carotid artery stenosis. DESIGN A retrospective review of all patients who underwent both carotid duplex and angiography in a 1-year period at a vascular unit which participates in the ACST trial. METHODS Peak systolic velocity was used as a primary end-point in carotid duplex examinations with a PSV > 130 cm/s used as an indication for angiographic assessment. Biplanar arch aortography and selective carotid catheterisation were performed as indicated and diameter reduction calculated by the ECST method. RESULTS The sensitivity of 130 cm/s for the detection of a 70% stenosis was 96% and the specificity 67%. If a PSV of 250 cm/s were used the sensitivity would be only 37% and specificity 96%. CONCLUSIONS Applying duplex criteria from one centre to another is inappropriate. Laboratory specific audit of duplex and angiography is essential before deciding to abandon preoperative angiography for carotid disease.
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Affiliation(s)
- P J Curley
- Department of Vascular Surgery, Hull Royal Infirmary, U.K
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20
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Dyet JF, Gaines PA, Nicholson AA, Cleveland T, Cook AM, Wilkinson AR, Galloway JM, Beard J. Treatment of chronic iliac artery occlusions by means of percutaneous endovascular stent placement. J Vasc Interv Radiol 1997; 8:349-53. [PMID: 9152906 DOI: 10.1016/s1051-0443(97)70570-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [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: 02/04/2023] Open
Abstract
PURPOSE A retrospective evaluation of outcomes in patients with chronic iliac occlusions treated with insertion of metallic endovascular stents, without previous thrombolysis, on an intention-to-treat basis. MATERIALS AND METHODS Seventy-two patients with chronic iliac occlusion underwent attempted stent placement from either the ipsilateral or contralateral femoral artery. There were 49 men and 23 women. Mean age was 63.1 years (range, 39-88 years). A total of 89 stents were deployed in 67 patients. Follow-up was from 24 to 69 months (mean, 37.5 months). RESULTS Stents were successfully deployed in 67 patients (93%), with two early failures, giving a primary success rate of 90%. There were five significant and four insignificant procedural complications. There were four late failures (all within the first year) and four non-stent-related deaths. CONCLUSION Endovascular stent placement offers an alternative to surgery in the treatment of chronic iliac occlusions.
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Affiliation(s)
- J F Dyet
- Department of Radiology, Hull Royal Infirmary, England
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21
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Affiliation(s)
- P Curley
- Department of Vascular Surgery, Hull Royal Infirmary, UK
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22
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Last GC, Curley P, Galloway JM, Wilkinson A. Impact of the New Deal on vascular surgical training. Ann R Coll Surg Engl 1996; 78:263-6. [PMID: 8944496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The rapid development and technological advances in vascular surgery have provided the impetus for the establishment of dedicated pure vascular surgical services. It remains unclear whether all vascular surgery will be provided by such units in the future or whether several district general hospitals will combine resources and provide dedicated vascular on-call rotas between surgeons on separate sites. Training in vascular surgery is also changing rapidly. A modular training scheme encompassing three levels of training has been recommended (1). Some of the training will only be performed in large training units, but there remains a requirement for general surgeons to be exposed to some vascular surgery during their training. The "New Deal' for junior doctors has imposed limits on the amount of hours worked during a week. Junior doctors should not on average be contracted for more than 72 hours a week or work more than 56 (2). The maximum on-call rota which fulfils these criteria is a 1 in 4 on-call with no early starts, late finishes and no prospective cover. Allowing for holidays, study leave, early starts and late finishes a 1 in 5 or 1 in 6 rota system is required. Implementation of the Calman report in higher specialist training would reduce the time spent in training at high specialist level to perhaps five years. In a modular training programme in vascular surgery there may be as little as one year Level II training spent in vascular surgery or perhaps two years if the candidate opted to have vascular surgery as their only sub-specialty. In an attempt to assess the impact of the New Deal and the Calman report on vascular surgical training we have assessed the exposure to vascular surgical procedure of hypothetical trainees on a 1 in 6 rota.
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Geroulakos G, Botchway LT, Pai V, Wilkinson AR, Galloway JM. Effect of carotid endarterectomy on the ocular circulation and on ocular symptoms unrelated to emboli. Eur J Vasc Endovasc Surg 1996; 11:359-63. [PMID: 8601250 DOI: 10.1016/s1078-5884(96)80086-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To evaluate haemodynamic changes in the ophthalmic artery and the retina following carotid endarterectomy and their effect on the pathophysiology of the eye. DESIGN Prospective study. METHOD Twenty-two consecutive patients with severe carotid stenosis underwent 23 carotid endarterectomies and one subclavian-carotid bypass. The following measurements were made preoperatively and 3 months after operation; Ophthalmic artery (OA) and retinal arteriole (RA) peak systolic velocity (PSV) and peak diastolic velocity (PDV), macular photostress recovery time, visual acuity, intraocular pressures, colour vision and visual fields testing. RESULT The RA PSV increased by 50% (p = 0.005) and PDV increased by 22% (p = 0.03). The OA PSV increased by 51% (p = 0.001). Macular photostress testing decreased from 58 s to 42 s (p = 0.001). Visual acuity improved in four and was unchanged in 13 eyes ipsilateral to the endarterectomy which had abnormal preoperative measurements. One patient experienced a dramatic increase in the ipsilateral intraocular pressure associated with visual deterioration. In two patients there was resolution of periorbital pain. CONCLUSION Our results demonstrate an increase in the PSV of the RA and OA following carotid surgery. There are pathophysiological changes in the eye, which accompany tight stenotic extracranial carotid artery disease and these may be influenced by carotid endarterectomy.
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Affiliation(s)
- G Geroulakos
- Department of Vascular Surgery, Hull Royal Infirmary, U.K
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Affiliation(s)
- A Nicholson
- Department of Cardiovascular Radiology, Royal Hull Hospital Trust, Kingston upon Hull, UK
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25
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Black IW, Fatkin D, Sagar KB, Khandheria BK, Leung DY, Galloway JM, Feneley MP, Walsh WF, Grimm RA, Stollberger C. Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study. Circulation 1994; 89:2509-13. [PMID: 8205657 DOI: 10.1161/01.cir.89.6.2509] [Citation(s) in RCA: 192] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Transesophageal echocardiography (TEE) has been used recently to detect atrial thrombi before cardioversion of atrial arrhythmias. It has been assumed that embolic events after cardioversion result from embolism of preexisting atrial thrombi that are accurately detected by TEE. This study examined the clinical and echocardiographic findings in patients with embolism after cardioversion of atrial fibrillation despite exclusion of atrial thrombi by TEE. METHODS AND RESULTS Clinical and echocardiographic data in 17 patients with embolic events after TEE-guided electrical (n = 16) or pharmacological (n = 1) cardioversion were analyzed. All 17 patients had nonvalvular atrial fibrillation, including four patients with lone atrial fibrillation. TEE before cardioversion showed left atrial spontaneous echo contrast in five patients and did not show atrial thrombus in any patient. Cardioversion resulted in return to sinus rhythm without immediate complication in all patients. Thirteen patients had cerebral embolic events and four patients had peripheral embolism occurring 2 hours to 7 days after cardioversion. None of the patients were therapeutically anticoagulated at the time of embolism. New or increased left atrial spontaneous echo contrast was detected in four of the five patients undergoing repeat TEE after cardioversion including one patient with a new left atrial appendage thrombus. CONCLUSIONS Embolism may occur after cardioversion of atrial fibrillation in inadequately anticoagulated patients despite apparent exclusion of preexisting atrial thrombus by TEE. These findings suggest de novo atrial thrombosis after cardioversion or imperfect sensitivity of TEE for atrial thrombi and suggest that screening by TEE does not obviate the requirement for anticoagulant therapy at the time of and after cardioversion. A randomized clinical trial is needed to compare conventional anticoagulant management with a TEE-guided strategy including anticoagulation after cardioversion.
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Affiliation(s)
- I W Black
- Department of Cardiology, Cleveland Clinic Foundation, OH 44195
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26
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Appleton CP, Galloway JM, Gonzalez MS, Gaballa M, Basnight MA. Estimation of left ventricular filling pressures using two-dimensional and Doppler echocardiography in adult patients with cardiac disease. Additional value of analyzing left atrial size, left atrial ejection fraction and the difference in duration of pulmonary venous and mitral flow velocity at atrial contraction. J Am Coll Cardiol 1993; 22:1972-82. [PMID: 8245357 DOI: 10.1016/0735-1097(93)90787-2] [Citation(s) in RCA: 566] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVES The purpose of this study was to determine whether left atrial size and ejection fraction are related to left ventricular filling pressures in patients with coronary artery disease. BACKGROUND In patients with coronary artery disease, left ventricular filling pressures can be estimated by using Doppler mitral and pulmonary venous flow velocity variables. However, because these flow velocities are age dependent, additional variables that indicate elevated left ventricular filling pressures are needed to increase diagnostic accuracy. METHODS Echocardiographic left atrial and Doppler mitral and pulmonary venous flow velocity variables were correlated with left ventricular filling pressures in 70 patients undergoing cardiac catheterization. RESULTS Left atrial size and volumes were larger and left atrial ejection fractions were lower in patients with elevated left ventricular filling pressures. Mean pulmonary wedge pressure was related to mitral E/A wave velocity ratio (r = 0.72), left atrial minimal volume (r = 0.70), left atrial ejection fraction (r = -0.66) and atrial filling fraction (r = -0.66). Left ventricular end-diastolic and A wave pressures were related to the difference in pulmonary venous and mitral A wave duration (both r = 0.77). By stepwise multilinear regression analysis, the ratio of mitral E to A wave velocity was the most important determinant of pulmonary wedge (r = 0.63) and left ventricular pre-A wave (r = 0.75) pressures, whereas the difference in pulmonary venous and mitral A wave duration was the most important variable for both left ventricular A wave (r = 0.75) and left ventricular end-diastolic (r = 0.80) pressures. The sensitivity of a left atrial minimal volume > 40 cm3 for identifying a mean pulmonary wedge pressure > 12 mm Hg was 82%, with a specificity of 98%. CONCLUSIONS Left atrial size, left atrial ejection fraction and the difference between mitral and pulmonary venous flow duration at atrial contraction are independent determinants of left ventricular filling pressures in patients with coronary artery disease. The additive value of left atrial size and Doppler variables in estimating filling pressures and the possibility that left atrial size may be less age dependent than other mitral and pulmonary venous flow velocity variables merit further investigation.
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Affiliation(s)
- C P Appleton
- Cardiology Section, Veterans Affairs Medical Center, Tuscon, Arizona 85723
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Affiliation(s)
- J V Reynolds
- Department of Surgery, Hull Royal Infirmary, Humberside, U.K
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Abstract
Low yield pressure of the lower esophageal sphincter is associated with esophageal reflux, and fundoplication must increase yield pressure if it is to prevent reflux. We attempted to increase yield pressure endoscopically in the dog by using the Nd:YAG laser to produce a fibrous scar at the cardia in the approximate line of the gastric sling fibers. Ten beagle dogs were studied. In a pilot study with two dogs, 15 watts for 4.2 sec were found to produce a scar deep into the muscle coat of the stomach. Three configurations of scar were used. One produced significant rises in yield pressure in all four of the dogs treated, the second produced a significant rise in one of the two dogs treated, and the third caused a significant drop in yield pressure in the one dog treated. One dog died of gastric perforation 10 days after lasering, but no other animal experienced any ill effects. These findings may have therapeutic implications for the management of esophageal reflux.
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Affiliation(s)
- R C McGouran
- Department of Gastroenterology, Queen Elizabeth Hospital, Norfolk, England
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Abstract
Ninety-five patients, who underwent fine catheter peripheral angiography as outpatients, were followed up and assessed to determine the safety of this procedure. No patients reported any major side effects and in particular no patients experienced a rebleed from the arterial puncture site. This procedure could be safely adopted in any radiology department.
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Affiliation(s)
- J F Dyet
- Department of Radiology, Hull Royal Infirmary
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Bliss B, Mansfield AO, Shepherd R, Bradley JW, Naylor H, Vickery M, Fairgrieve J, Parry EW, Weale F, Galloway JM. Vascular injuries. J Bone Joint Surg Br 1989; 71:738. [PMID: 2684987 DOI: 10.1302/0301-620x.71b5.2684987] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Christopoulos D, Nicolaides AN, Cook A, Irvine A, Galloway JM, Wilkinson A. Pathogenesis of venous ulceration in relation to the calf muscle pump function. Surgery 1989; 106:829-35. [PMID: 2814817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Air plethysmography has been used to quantitate venous reflux by measuring the average filling rate of the veins (venous filling index; in milliliters per second) on standing from the supine position, the ejection fraction of the calf muscle pump as a result of one tip-toe movement, and the residual volume fraction after 10 tip-toe movements. Thirty normal limbs, 110 limbs with primary varicose veins, 34 limbs with reflux in the deep veins but without occlusion, and 31 limbs with deep venous occlusion, with or without reflux, have been studied. An increase in the incidence of ulceration occurred with increasing values of reflux and decreasing values of the calf muscle pump ejection fraction. A poor ejection fraction was the primary cause of venous ulceration in limbs with minimal reflux. A good ejection fraction, however, significantly reduced the incidence of ulceration in limbs with marked reflux (p less than 0.05). The residual volume fraction, which expresses the combined effect of venous reflux and ejection fraction with rhythmic exercise, showed a good correlation with the incidence of ulceration and the measurements of ambulatory venous pressure (r = 0.81). The air-plethysmographic measurements completely assess the calf muscle pump function and provide an accurate method to identify the predominant hemodynamic factor (ejection fraction, reflux, or both) responsible for the clinical picture of the patient.
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Affiliation(s)
- D Christopoulos
- Irvine Laboratory for Cardiovascular Investigations and Research, St. Mary's Hospital, London, England
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Abstract
Yield pressure at the cardia was measured before and after fundoplication in 10 patients; five had a Nissen fundoplication and five a Belsey mark IV procedure. Surgery was considered successful if oesophagitis healed or if 24 hour pH monitoring returned to normal. There was a marked rise in yield pressure in all eight patients with a successful operation. Yield pressure remained low in two patients in whom oesophagitis persisted.
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Affiliation(s)
- R C McGouran
- Department of Gastroenterology, Queen Elizabeth Hospital, King's Lynn, Norfolk
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Christopoulos D, Galloway JM, Grigg MJ. A perioperative technique for detection of retained valve cusps in the in situ vein graft. Surgery 1989; 105:553-5. [PMID: 2928957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A problem of the in situ vein bypass technique is the retained value cusp. To ensure that maximum flow has been obtained through the vein graft after valvotomy, a simple perioperative technique has been developed. This consists of infusing normal saline solution into the vein and comparing the distal to proximal (antegrade) flow with the proximal to distal (retrograde) flow under the same conditions. Twelve consecutive in situ vein grafts have been assessed. Antegrade and retrograde flow measurements were similar in four of the grafts but different in eight (40% to 80% reduced retrograde flow). Valvotomy was repeated and subsequent measurements of retrograde flow were similar or greater than the antegrade. The technique described is simple, reproducible, inexpensive, and may prove useful for routine intraoperative evaluation of valvotomy of in situ vein grafts.
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Affiliation(s)
- D Christopoulos
- Department of Vascular Surgery, Hull Royal Infirmary, England
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34
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Abstract
The hemodynamic effect of conventional surgery for varicose veins has been evaluated with a new method of air-plethysmography. The functional venous volume of the leg, venous reflux, and calf muscle pump-ejecting capacity have been measured in 42 legs with primary varicose veins. The patients were studied clinically, with Doppler ultrasound, duplex scanning, and phlebography preoperatively. Doppler ultrasound was repeated postoperatively. Air-plethysmography was performed one day before surgery and 8 to 10 days after surgery. A decrease of the functional venous volume of 16% has been observed (p less than 0.001). The abolition of venous reflux has been shown in all the patients. An improvement in the calf muscle pump-ejecting capacity has also been shown, with a 30% increase of the ejection fraction of the calf muscle pump and with a 43% decrease of the residual volume fraction after 10 tiptoe movements (p less than 0.001). The results indicate that this new method of air-plethysmography apart from its diagnostic value offers a new and unique technique for a noninvasive, objective, and quantitative evaluation of the results of established and experimental venous surgery.
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Affiliation(s)
- D Christopoulos
- Irvine Laboratory for Cardiovascular Investigations and Research, St. Mary's Hospital Medical School, London, England
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McGouran RC, Galloway JM, Spence DS, Morton CP, Marchant D. Does measurement of yield pressure at the cardia during endoscopy provide information on the function of the lower oesophageal sphincter mechanism? Gut 1988; 29:275-8. [PMID: 3356356 PMCID: PMC1433611 DOI: 10.1136/gut.29.3.275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We describe a technique for measuring the yield pressure at the cardia during upper gastrointestinal endoscopy. The test was applied to 47 patients with macroscopic oesophagitis and nine patients with achalasia. Controls were 123 patients from the routine endoscopy list in whom no abnormality was found and 21 healthy volunteers. Yield pressure was similar in both control groups, but was significantly higher in achalasia (p less than 0.001) and lower in oesophagitis (p less than 0.001). Yield pressures fell dramatically after pneumatic dilatation in the achalasia patients. The test was reproducible and yield pressure was not affected by age, sex, weight, or sedation. Measurement of yield pressure during endoscopy provides information which may reflect the function of the whole antireflux mechanism, and not just the lower oesophageal sphincter.
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Affiliation(s)
- R C McGouran
- Department of Gastroenterology, Queen Elizabeth Hospital, Norfolk
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Mohammed AM, Wilkinson AR, Galloway JM. Upper limb vascular injuries. J R Coll Surg Edinb 1984; 29:210-3. [PMID: 6481668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Stanley NN, Galloway JM, Flint KC, Campbell DB. Increased respiratory chemosensitivity induced by oral almitrine in healthy man. Br J Dis Chest 1983; 77:136-46. [PMID: 6871083 DOI: 10.1016/0007-0971(83)90019-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cardiorespiratory effects of 50 mg and 100 mg doses of almitrine and placebo given orally on separate test days to twelve healthy volunteers were assessed in a double-blind crossover study. The drug caused no significant changes in ventilation, mixed venous CO2 tension, metabolic rate, heart rate or blood pressure while they were resting and breathing room air. With progressive hypercapnia, however, the ventilatory response increased by 5% after the 50 mg dose (NS) and by 27% after the 100 mg dose (P less than 0.05). There were greater increases in the response to progressive hypoxia by 78% after 50 mg of almitrine (P less than 0.01) and by 120% after 100 mg (P less than 0.01), which was also significantly greater than the increase after the 50 mg dose (P less than 0.01). In contrast there were only minor and inconsistent changes in chemosensitivity after administering placebo. The findings are consistent with an agonist action of almitrine in the peripheral chemoreceptors and suggest that it may have clinical value in managing respiratory failure due to hypoventilation.
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Stanley NN, Galloway JM, Gordon B, Pauly N. Increased respiratory chemosensitivity induced by infusing almitrine intravenously in healthy man. Thorax 1983; 38:200-4. [PMID: 6134350 PMCID: PMC459519 DOI: 10.1136/thx.38.3.200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The respiratory effects of intravenously infused almitrine were evaluated in healthy volunteers. In the dose range 0.25-1.0 mg/kg/hour it caused large and dose-dependent increases in hypoxic chemosensitivity, which were longlasting and more persistent than the drug's retention in the plasma. Increases in sensitivity to hypercapnia were much less and were detected only when the plasma almitrine exceeded 200 ng/ml. Small increases in resting ventilation and metabolic rate with a decrease in mixed venous carbon dioxide tension occurred only at the highest infusion rate. The findings accord with an action of almitrine in the peripheral chemoreceptors, which may be of therapeutic value in managing some cases of respiratory failure.
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Galloway JM. A growing concern: hospitals and the unrelated business income tax. Healthc Financ Manage 1982; 36:38-42. [PMID: 10315237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Abstract
A 62-year-old man with intermittent claudication but normal foot pulses at rest had no atheroma shown on femoral arteriography. There was evidence of external compression of the artery at the level of a popliteal cyst which was demonstrated by arthrography on films taken after sufficient exercise to be in communication with the knee joint. At operation the cyst was continuous with changes of cystic adventitial disease of the popliteal artery. Both the main cyst and th cystic changes in the artery were removed. Postoperatively the patient's claudication disappeared. Evidence is presented that synovial cysts play a part in the production of arterial cystic adventitial disease.
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Galloway JM. Hospital and donor both benefit from deferred gift. Hosp Financ Manage 1979; 33:66-8, 70. [PMID: 10244285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Galloway JM. Tax benefits of property gifts. Hosp Financ Manage 1978; 32:8-11. [PMID: 10308278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Galloway JM. The swollen leg. Practitioner 1977; 218:676-81. [PMID: 887539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Gabriel R, Galloway JM, Newling DW. Late haemorrhage following renal biopsy. Br J Urol 1975; 47:358. [PMID: 1180978 DOI: 10.1111/j.1464-410x.1975.tb03983.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Karmody AM, Galloway JM. Aneurysm of the profunda femoris artery. J R Coll Surg Edinb 1972; 17:261-3. [PMID: 5073914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
Abstract
Serious haemorrhage late in the course of severe acute pancreatitis is an uncommon but wellrecognized condition. Massive intraperitoneal bleeding as a presenting symptom is extremely rare and has not previously been recorded. A case where bleeding occurred from the left gastric artery is presented. Attention is drawn to the need for laparotomy or paracentesis in the profoundly shocked patient with pancreatitis who fails to respond to conservative care, for in such cases the haemorrhage may readily be arrested and a fatal outcome averted.
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Ewen SW, Anderson J, Galloway JM, Miller JD, Kyle J. Crohn's disease initially confined to the appendix. Gastroenterology 1971; 60:853-7. [PMID: 5581328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Abstract
Abstract
Experiments have been carried out in dogs to determine the optimal method of use of streptokinase in venous thrombosis.
The experiments show that:– High-dose regional infusion is the most efficient system of producing thrombolysis.Occlusive thrombi are readily removed by this system.Low-dose regional infusions and high-dose systemic infusions are much less efficient but, in general, regional delivery is preferable when possible.
As a result of these experimental conclusions a number of patients have been successfully treated with high-dose regional infusions of streptokinase (Mavor, Bennett, Galloway, and Karmody, 1969; Mavor, Galloway, and Karmody, 1970).
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Mavor GE, Galloway JM, Karmody AM. The surgical aspects of deep vein thrombosis. Proc R Soc Med 1970; 63:126-31. [PMID: 5440749 PMCID: PMC1811315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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