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Riley JM, Caruso F, Verdi C, Duffy LB, Watson MD, Bawden L, Volckaert K, van der Laan G, Hesjedal T, Hoesch M, Giustino F, King PDC. Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO. Nat Commun 2018; 9:2305. [PMID: 29899336 PMCID: PMC5998015 DOI: 10.1038/s41467-018-04749-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 05/22/2018] [Indexed: 11/10/2022] Open
Abstract
Strong many-body interactions in solids yield a host of fascinating and potentially useful physical properties. Here, from angle-resolved photoemission experiments and ab initio many-body calculations, we demonstrate how a strong coupling of conduction electrons with collective plasmon excitations of their own Fermi sea leads to the formation of plasmonic polarons in the doped ferromagnetic semiconductor EuO. We observe how these exhibit a significant tunability with charge carrier doping, leading to a polaronic liquid that is qualitatively distinct from its more conventional lattice-dominated analogue. Our study thus suggests powerful opportunities for tailoring quantum many-body interactions in solids via dilute charge carrier doping.
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Affiliation(s)
- J M Riley
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - F Caruso
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, 12489, Germany
| | - C Verdi
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - L B Duffy
- Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- ISIS, STFC, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - M D Watson
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - K Volckaert
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - G van der Laan
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - T Hesjedal
- Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK.
- DESY Photon Science, Deutsches Elektronen-Synchrotron, Hamburg, D-22603, Germany.
| | - F Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York, 14853, USA.
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
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2
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Clark OJ, Neat MJ, Okawa K, Bawden L, Marković I, Mazzola F, Feng J, Sunko V, Riley JM, Meevasana W, Fujii J, Vobornik I, Kim TK, Hoesch M, Sasagawa T, Wahl P, Bahramy MS, King PDC. Fermiology and Superconductivity of Topological Surface States in PdTe_{2}. Phys Rev Lett 2018; 120:156401. [PMID: 29756894 DOI: 10.1103/physrevlett.120.156401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/17/2018] [Indexed: 05/12/2023]
Abstract
We study the low-energy surface electronic structure of the transition-metal dichalcogenide superconductor PdTe_{2} by spin- and angle-resolved photoemission, scanning tunneling microscopy, and density-functional theory-based supercell calculations. Comparing PdTe_{2} with its sister compound PtSe_{2}, we demonstrate how enhanced interlayer hopping in the Te-based material drives a band inversion within the antibonding p-orbital manifold well above the Fermi level. We show how this mediates spin-polarized topological surface states which form rich multivalley Fermi surfaces with complex spin textures. Scanning tunneling spectroscopy reveals type-II superconductivity at the surface, and moreover shows no evidence for an unconventional component of its superconducting order parameter, despite the presence of topological surface states.
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Affiliation(s)
- O J Clark
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - M J Neat
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - K Okawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - I Marković
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - F Mazzola
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - J Feng
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
- Suzhou Institute of Nano-Tech. and Nanobionics (SINANO), CAS, 398 Ruoshui Road, SEID, SIP, Suzhou 215123, China
| | - V Sunko
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - J M Riley
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - W Meevasana
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
- ThEP, Commission of Higher Education, Bangkok 10400, Thailand
| | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - T Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - P Wahl
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - M S Bahramy
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- RIKEN center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
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3
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Sunko V, Rosner H, Kushwaha P, Khim S, Mazzola F, Bawden L, Clark OJ, Riley JM, Kasinathan D, Haverkort MW, Kim TK, Hoesch M, Fujii J, Vobornik I, Mackenzie AP, King PDC. Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking. Nature 2018; 549:492-496. [PMID: 28959958 DOI: 10.1038/nature23898] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/26/2017] [Indexed: 11/09/2022]
Abstract
Engineering and enhancing the breaking of inversion symmetry in solids-that is, allowing electrons to differentiate between 'up' and 'down'-is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies-that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with spin-orbit interactions, can mediate Rashba-like spin splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the spin splitting in the CoO2- and RhO2-derived surface states of delafossite oxides becomes controlled by the full atomic spin-orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like spin splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.
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Affiliation(s)
- Veronika Sunko
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK.,Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - H Rosner
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - P Kushwaha
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - S Khim
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - F Mazzola
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - O J Clark
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - J M Riley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK.,Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - D Kasinathan
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - M W Haverkort
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany.,Institute for Theoretical Physics, Heidelberg University, Philosophenweg 19, 69120 Heidelberg, Germany
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S.14, Km 163.5, 34149 Trieste, Italy
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S.14, Km 163.5, 34149 Trieste, Italy
| | - A P Mackenzie
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK.,Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
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4
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Bahramy MS, Clark OJ, Yang BJ, Feng J, Bawden L, Riley JM, Marković I, Mazzola F, Sunko V, Biswas D, Cooil SP, Jorge M, Wells JW, Leandersson M, Balasubramanian T, Fujii J, Vobornik I, Rault JE, Kim TK, Hoesch M, Okawa K, Asakawa M, Sasagawa T, Eknapakul T, Meevasana W, King PDC. Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides. Nat Mater 2018; 17:21-28. [PMID: 29180775 DOI: 10.1038/nmat5031] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 10/13/2017] [Indexed: 05/12/2023]
Abstract
Transition-metal dichalcogenides (TMDs) are renowned for their rich and varied bulk properties, while their single-layer variants have become one of the most prominent examples of two-dimensional materials beyond graphene. Their disparate ground states largely depend on transition metal d-electron-derived electronic states, on which the vast majority of attention has been concentrated to date. Here, we focus on the chalcogen-derived states. From density-functional theory calculations together with spin- and angle-resolved photoemission, we find that these generically host a co-existence of type-I and type-II three-dimensional bulk Dirac fermions as well as ladders of topological surface states and surface resonances. We demonstrate how these naturally arise within a single p-orbital manifold as a general consequence of a trigonal crystal field, and as such can be expected across a large number of compounds. Already, we demonstrate their existence in six separate TMDs, opening routes to tune, and ultimately exploit, their topological physics.
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Affiliation(s)
- M S Bahramy
- Quantum-Phase Electronics Center and Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
- RIKEN center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - O J Clark
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - B-J Yang
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Korea
- Center for Theoretical Physics (CTP), Seoul National University, Seoul 08826, Korea
| | - J Feng
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO) CAS, 398 Ruoshi Road, SEID, SIP, Suzhou 215123, China
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - J M Riley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - I Marković
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - F Mazzola
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - V Sunko
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - D Biswas
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - S P Cooil
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - M Jorge
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - J W Wells
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - M Leandersson
- MAX IV Laboratory, Lund University, PO Box 118, 221 00 Lund, Sweden
| | | | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - J E Rault
- Synchrotron SOLEIL, CNRS-CEA, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 Gif-sur-Yvette, France
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - K Okawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - M Asakawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - T Sasagawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - T Eknapakul
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - W Meevasana
- School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- ThEP, Commission of Higher Education, Bangkok 10400, Thailand
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
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5
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Riley JM, Meevasana W, Bawden L, Asakawa M, Takayama T, Eknapakul T, Kim TK, Hoesch M, Mo SK, Takagi H, Sasagawa T, Bahramy MS, King PDC. Negative electronic compressibility and tunable spin splitting in WSe2. Nat Nanotechnol 2015; 10:1043-1047. [PMID: 26389661 DOI: 10.1038/nnano.2015.217] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 08/20/2015] [Indexed: 06/05/2023]
Abstract
Tunable bandgaps, extraordinarily large exciton-binding energies, strong light-matter coupling and a locking of the electron spin with layer and valley pseudospins have established transition-metal dichalcogenides (TMDs) as a unique class of two-dimensional (2D) semiconductors with wide-ranging practical applications. Using angle-resolved photoemission (ARPES), we show here that doping electrons at the surface of the prototypical strong spin-orbit TMD WSe2, akin to applying a gate voltage in a transistor-type device, induces a counterintuitive lowering of the surface chemical potential concomitant with the formation of a multivalley 2D electron gas (2DEG). These measurements provide a direct spectroscopic signature of negative electronic compressibility (NEC), a result of electron-electron interactions, which we find persists to carrier densities approximately three orders of magnitude higher than in typical semiconductor 2DEGs that exhibit this effect. An accompanying tunable spin splitting of the valence bands further reveals a complex interplay between single-particle band-structure evolution and many-body interactions in electrostatically doped TMDs. Understanding and exploiting this will open up new opportunities for advanced electronic and quantum-logic devices.
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Affiliation(s)
- J M Riley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - W Meevasana
- School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - M Asakawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - T Takayama
- Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033, Japan
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - T Eknapakul
- School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - S-K Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley California 94720, USA
| | - H Takagi
- Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033, Japan
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - T Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Kanagawa 226-8503, Japan
| | - M S Bahramy
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
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6
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Lip GY, Bawden L, Hodson R, Rutland E, Snatchfold J, Beevers DG. Atrial fibrillation amongst the Indo-Asian general practice population. The West Birmingham Atrial Fibrillation Project. Int J Cardiol 1998; 65:187-92. [PMID: 9706815 DOI: 10.1016/s0167-5273(98)00125-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [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: 02/08/2023]
Abstract
Whilst there are recognised ethnic differences in cardiovascular disease, with a higher prevalence of hypertension and complications such as stroke amongst black/Afro-Caribbean populations, and ischaemic heart disease being more prevalent amongst Indo-Asians, the literature describing the clinical epidemiology of atrial fibrillation (AF) in non-caucasian groups is scarce. To survey the clinical features and management amongst Indo-Asian patients with known AF, we studied patients from six general practices in the west of Birmingham. The six general practices had a combined practice population of 25051, from which, the Indo-Asian population was 14670. A total of 12 Indo-Asian patients (six male, six female; mean age, 67 years; range, 42 to 95 years) with known AF were identified, suggesting a prevalence of AF in Indo-Asians aged >50 years of 0.6%. Six patients had chronic AF, two had recent onset (defined as onset <six months) and four had paroxysmal AF. Five patients had a history of ischaemic heart disease, three had hypertension, seven had heart failure, two had alcohol excess, four had mitral valve disease, and one patient with paroxysmal AF had sick sinus syndrome. None could be classified as having lone AF. Only four patients were anticoagulated, but, of the remaining eight, who were not taking warfarin, six were taking aspirin. None of the patients had contraindications to warfarin, but one of the patients who was taking aspirin had poor compliance to warfarin. In this survey of a general practice Indo-Asian population of approximately 14670, we found 12 patients with known AF. More information on the clinical epidemiology of AF in non-caucasian groups is still needed and urgently required, in view of the public health implications of this common cardiac arrhythmia.
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Affiliation(s)
- G Y Lip
- University Department of Medicine, City Hospital, Birmingham, UK.
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7
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Hunter MG, Bawden L, Brotherton D, Craig S, Cribbes S, Czaplewski LG, Dexter TM, Drummond AH, Gearing AH, Heyworth CM, Lord BI, McCourt M, Varley PG, Wood LM, Edwards RM, Lewis PJ. BB-10010: an active variant of human macrophage inflammatory protein-1 alpha with improved pharmaceutical properties. Blood 1995; 86:4400-8. [PMID: 8541527] [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: 01/31/2023] Open
Abstract
The stem cell inhibitor, macrophage inflammatory protein-1 alpha (MIP-1 alpha) or LD78, protects multipotent hematopoietic progenitors in murine models from the cytotoxic effects of chemotherapy. Clinical use of human MIP-1 alpha during chemotherapy could therefore lead to faster hematologic recovery and may allow dose intensification. We have also shown that human MIP-1 alpha causes the rapid mobilization of hematopoietic cells, suggesting an additional clinical use in peripheral blood stem cell transplantation. However, the clinical evaluation of human MIP-1 alpha is complicated by its tendency to associate and form high molecular weight polymers. We have produced a variant of rhMIP-1 alpha, BB-10010, carrying a single amino acid substitution of Asp26 > Ala, with a reduced tendency to form large polymers at physiologic pH and ionic strength. This greatly increases its solubility, facilitating its production and clinical formulation. We confirmed the potency of BB-10010 as a human MIP-1 alpha-like agonist in receptor binding, calcium mobilization, inhibition of colony formation, and thymidine suicide assays. The myeloprotective activity of BB-10010 was shown in a murine model of repeated chemotherapy using hydroxyurea. BB-10010 is therefore an ideal variant with which to evaluate the therapeutic potential of recombinant human MIP-1 alpha.
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Affiliation(s)
- M G Hunter
- British Biotech Pharmaceuticals Ltd, Oxford, UK
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Sutton C, Depledge P, Bawden L, Carne A, Meltzer M, Newton V, Vodinelich L. Purification and sequencing of glycosylation variants of BSF-1, as a MAF, from the EL-4 leukaemia cell line. J Biol Stand 1989; 17:65-74. [PMID: 2646299 DOI: 10.1016/0092-1157(89)90029-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Macrophage activation activity was characterized from a PMA-induced subclone of the murine EL-4 leukaemic cell line. The MAF was purified from the cell line culture supernatant by concentration, CM-Sepharose and lentil lectin Sepharose chromatography, AcA 54 gel filtration, Mono Q FPLC and reverse phase HPLC. Four protein bands of different abundance were observed on SDS-PAGE with molecular weights of 17,500 to 21,000 Da. Three of the four proteins were sequenced from the N-terminal and shared homology with the published sequence of BSF-1. Variation of the molecular weight due to glycosylation was demonstrated by N-glycanase treatment, all four proteins gave a band of 14,200 Da after deglycosylation. Both glycosylated and deglycosylated forms of BSF-1 were equally active in the MAF assay. A monoclonal antibody to BSF-1 neutralized 80% of the activity from crude culture supernatants in the MAF assay. These studies have indicated that BSF-1 is the major, if not the only, MAF activity from this particular subline of the murine EL-4 leukaemic cell line.
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9
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Abstract
The use of a monoclonal antibody (MAb) affinity column to purify epidermal growth factor/urogastrone from human urine in a single-step process is described. The MAb was raised against purified recombinant human urogastrone derived from the expression of a cloned synthetic urogastrone gene. The MAb was characterised and shown to cross-react fully with recombinant and native human urogastrones. The material eluted from the column was shown to have retained biological activity. When the eluted material was run on SDS/PAGE under reducing conditions an apparently homogeneous species of 5400 Da apparent molecular weight was seen. When examined on acid PAGE, 2 molecular species corresponding to beta and gamma urogastrone were observed.
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