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Iyer RS, Needham SR, Galdadas I, Davis BM, Roberts SK, Man RCH, Zanetti-Domingues LC, Clarke DT, Fruhwirth GO, Parker PJ, Rolfe DJ, Gervasio FL, Martin-Fernandez ML. Drug-resistant EGFR mutations promote lung cancer by stabilizing interfaces in ligand-free kinase-active EGFR oligomers. Nat Commun 2024; 15:2130. [PMID: 38503739 PMCID: PMC10951324 DOI: 10.1038/s41467-024-46284-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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 02/20/2024] [Indexed: 03/21/2024] Open
Abstract
The Epidermal Growth Factor Receptor (EGFR) is frequently found to be mutated in non-small cell lung cancer. Oncogenic EGFR has been successfully targeted by tyrosine kinase inhibitors, but acquired drug resistance eventually overcomes the efficacy of these treatments. Attempts to surmount this therapeutic challenge are hindered by a poor understanding of how and why cancer mutations specifically amplify ligand-independent EGFR auto-phosphorylation signals to enhance cell survival and how this amplification is related to ligand-dependent cell proliferation. Here we show that drug-resistant EGFR mutations manipulate the assembly of ligand-free, kinase-active oligomers to promote and stabilize the assembly of oligomer-obligate active dimer sub-units and circumvent the need for ligand binding. We reveal the structure and assembly mechanisms of these ligand-free, kinase-active oligomers, uncovering oncogenic functions for hitherto orphan transmembrane and kinase interfaces, and for the ectodomain tethered conformation of EGFR. Importantly, we find that the active dimer sub-units within ligand-free oligomers are the high affinity binding sites competent to bind physiological ligand concentrations and thus drive tumor growth, revealing a link with tumor proliferation. Our findings provide a framework for future drug discovery directed at tackling oncogenic EGFR mutations by disabling oligomer-assembling interactions.
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Affiliation(s)
- R Sumanth Iyer
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
- Immunocore Limited, 92 Park Drive, Milton Park, Abingdon, UK
| | - Sarah R Needham
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Ioannis Galdadas
- School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland
- ISPSO, University of Geneva, Geneva, Switzerland
| | - Benjamin M Davis
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Selene K Roberts
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Rico C H Man
- Imaging Therapies and Cancer Group, Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | | | - David T Clarke
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
| | - Gilbert O Fruhwirth
- Imaging Therapies and Cancer Group, Comprehensive Cancer Centre, School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, London, UK
- School of Cancer and Pharmaceutical Sciences, Guy's Campus, King's College London, London, UK
| | - Daniel J Rolfe
- Central Laser Facility, UKRI-STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK.
| | - Francesco L Gervasio
- School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
- ISPSO, University of Geneva, Geneva, Switzerland.
- Chemistry Department, University College London, London, UK.
- Swiss Institute of Bioinformatics, University of Geneva, Geneva, Switzerland.
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Batt NM, Rodrigues B, Bloom S, Sawhney R, George ES, Hodge A, Vootukuru N, McCrae C, Sood S, Roberts SK, Dev A, Bell S, Thompson A, Ryan MC, Kemp W, Gow PJ, Sood S, Nicoll AJ. Metabolic-associated fatty liver disease and hepatocellular carcinoma: a prospective study of characteristics and response to therapy. J Gastroenterol Hepatol 2024. [PMID: 38369382 DOI: 10.1111/jgh.16501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/31/2023] [Accepted: 01/16/2024] [Indexed: 02/20/2024]
Abstract
BACKGROUND AND AIM The rising incidence of hepatocellular carcinoma (HCC) in Australia is related to increasing rates of metabolic-associated fatty liver disease (MAFLD). This study aimed to prospectively characterize the metabolic profile, lifestyle, biometric features, and response to treatment of HCC patients in an Australian population. METHOD Multicenter prospective cohort analysis of newly diagnosed HCC patients at six multidisciplinary team meetings over a 2-year period. RESULTS Three hundred and thirteen (313) newly diagnosed HCC patients with MAFLD (n = 77), MAFLD plus other liver disease (n = 57) (the "mixed" group), and non-MAFLD (n = 179) were included in the study. Alcohol-associated liver disease (ALD) (43%) and MAFLD (43%) were the most common underlying liver diseases. MAFLD-HCC patients were older (73 years vs 67 years vs 63 years), more likely to be female (40% vs 14% vs 20%), less likely to have cirrhosis (69% vs 88% vs 85%), showed higher ECOG, and were less likely to be identified by screening (29% vs 53% vs 45%). Metabolic syndrome was more prevalent in the MAFLD and mixed groups. The severity of underlying liver disease and HCC characteristics were the same across groups. While the MAFLD population self-reported more sedentary lifestyles, reported dietary patterns were no different across the groups. Dyslipidemia was associated with tumor size, and those taking statins had a lower recurrence rate. CONCLUSION Equal to ALD, MAFLD is now the most common underlying liver disease seen in HCC patients in Australia. Future HCC prevention screening and treatment strategies need to take this important group of patients into consideration.
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Affiliation(s)
- N M Batt
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
| | - B Rodrigues
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
| | - S Bloom
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
- Eastern Health Clinical School, Monash University, Melbourne, Victoria, Australia
| | - R Sawhney
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
- Eastern Health Clinical School, Monash University, Melbourne, Victoria, Australia
| | - E S George
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - A Hodge
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
- Eastern Health Clinical School, Monash University, Melbourne, Victoria, Australia
| | - N Vootukuru
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
| | - C McCrae
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
| | - Surbhi Sood
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - S K Roberts
- Department of Gastroenterology, Alfred Health, Melbourne, Victoria, Australia
- Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - A Dev
- Department of Gastroenterology, Monash Health, Clayton, Victoria, Australia
| | - S Bell
- Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Gastroenterology, Monash Health, Clayton, Victoria, Australia
| | - A Thompson
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Victoria, Australia
- University of Melbourne, Parkville, Victoria, Australia
| | - M C Ryan
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Victoria, Australia
- University of Melbourne, Parkville, Victoria, Australia
| | - W Kemp
- Department of Gastroenterology, Alfred Health, Melbourne, Victoria, Australia
| | - P J Gow
- Department of Gastroenterology, Austin Health, Heidelberg, Victoria, Australia
| | - Siddharth Sood
- Department of Gastroenterology and Hepatology, Melbourne Health, Parkville, Victoria, Australia
| | - A J Nicoll
- Department of Gastroenterology, Eastern Health, Box Hill, Victoria, Australia
- Eastern Health Clinical School, Monash University, Melbourne, Victoria, Australia
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Needham SR, Iyer S, Davis B, Zanetti Domingues L, Roberts SK, Rolfe DR, Martin-Fernandez M. Investigating the Structure of Epidermal Growth Factor Receptor (EGFR) Dimers and Oligomers in Cells. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Freeman E, Cheung W, Kavnoudias H, Majeed A, Kemp W, Roberts SK. Irreversible Electroporation For Hepatocellular Carcinoma: Longer-Term Outcomes At A Single Centre. Cardiovasc Intervent Radiol 2020; 44:247-253. [PMID: 33051707 DOI: 10.1007/s00270-020-02666-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/22/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIMS Irreversible electroporation (IRE) is a non-thermal ablation technique for unresectable hepatocellular carcinoma (HCC) not amenable to standard thermal ablation. The aim of this study was to report our longer-term outcomes using this treatment modality. METHOD We identified all patients at our institution who underwent IRE for HCC between December 2008 and October 2019 as recommended after multi-disciplinary team review. Demographic, clinical, tumour response and survival data up until 1 March, 2020 were analysed. The primary outcome was local recurrence-free survival (LRFS) in patients who had a complete response (CR). Secondary outcomes included CR rates, procedure-related complications and the incidence of death or liver transplantation. RESULTS A total of 23 patients (78% males, median age 65.2 years) received IRE therapy to 33 HCC lesions during the study period with the median tumour size being 2.0 cm (range 1.0-5.0 cm). Twenty-nine (87.9%) lesions were successfully ablated after one (n = 26) or two (n = 3) procedures. The median follow-up time for these lesions was 20.4 months. The median overall LRFS was 34.5 (95% CI 24.8 -) months with a 6- and 12-month LRFS of 87.9% (95% CI 75.8-100) and 83.6% (95% CI 70.2-99.7), respectively. Tumours < 2 cm had a 12-month LRFS of 100% (95% CI 100-100). CONCLUSION IRE appears to be an efficacious local ablative method for early stage HCC not amenable to standard ablative techniques, with very good CR rates and longer-term LRFS, particularly for smaller lesions. Further studies comparing this technique to more widely accepted ablative methods such as radiofrequency and microwave ablation are warranted.
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Affiliation(s)
- E Freeman
- Department of Gastroenterology, Alfred Hospital, The Alfred55 Commercial Rd, Melbourne, 3004, Australia
| | - W Cheung
- Department of Radiology, Alfred Hospital, Melbourne, Australia
| | - H Kavnoudias
- Department of Radiology, Alfred Hospital, Melbourne, Australia
| | - A Majeed
- Department of Gastroenterology, Alfred Hospital, The Alfred55 Commercial Rd, Melbourne, 3004, Australia.,Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
| | - W Kemp
- Department of Gastroenterology, Alfred Hospital, The Alfred55 Commercial Rd, Melbourne, 3004, Australia.,Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
| | - S K Roberts
- Department of Gastroenterology, Alfred Hospital, The Alfred55 Commercial Rd, Melbourne, 3004, Australia. .,Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia.
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5
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Fedorenko OA, Kaufman IK, Gibby WAT, Barabash ML, Luchinsky DG, Roberts SK, McClintock PVE. Ionic Coulomb blockade and the determinants of selectivity in the NaChBac bacterial sodium channel. Biochim Biophys Acta Biomembr 2020; 1862:183301. [PMID: 32360369 DOI: 10.1016/j.bbamem.2020.183301] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 01/30/2020] [Accepted: 03/29/2020] [Indexed: 10/24/2022]
Abstract
Mutation-induced transformations of conductivity and selectivity in NaChBac bacterial channels are studied experimentally and interpreted within the framework of ionic Coulomb blockade (ICB), while also taking account of resonant quantised dehydration (QD) and site protonation. Site-directed mutagenesis and whole-cell patch-clamp experiments are used to investigate how the fixed charge Qf at the selectivity filter (SF) affects both valence selectivity and same-charge selectivity. The new ICB/QD model predicts that increasing ∣Qf∣ should lead to a shift in selectivity sequences toward larger ion sizes, in agreement with the present experiments and with earlier work. Comparison of the model with experimental data leads to the introduction of an effective charge Qf∗ at the SF, which was found to differ between Aspartate and Glutamate charged rings, and also to depend on position within the SF. It is suggested that protonation of the residues within the restricted space of the SF is important in significantly reducing the effective charge of the EEEE ring. Values of Qf∗ derived from experiments on divalent blockade agree well with expectations based on the ICB/QD model and have led to the first demonstration of ICB oscillations in Ca2+ conduction as a function of the fixed charge. Preliminary studies of the dependence of Ca2+ conduction on pH are qualitatively consistent with the predictions of the model.
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Affiliation(s)
- O A Fedorenko
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK; School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK.
| | - I Kh Kaufman
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - W A T Gibby
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
| | - M L Barabash
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
| | - D G Luchinsky
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK; SGT, Inc., Greenbelt, MD 20770, USA.
| | - S K Roberts
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, UK.
| | - P V E McClintock
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK.
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Elbediwy A, Zhang Y, Cobbaut M, Riou P, Tan RS, Roberts SK, Tynan C, George R, Kjaer S, Martin-Fernandez ML, Thompson BJ, McDonald NQ, Parker PJ. The Rho family GEF FARP2 is activated by aPKCι to control tight junction formation and polarity. J Cell Sci 2019; 132:jcs223743. [PMID: 30872454 PMCID: PMC6503954 DOI: 10.1242/jcs.223743] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/28/2019] [Indexed: 01/11/2023] Open
Abstract
The elaboration of polarity is central to organismal development and to the maintenance of functional epithelia. Among the controls determining polarity are the PAR proteins, PAR6, aPKCι and PAR3, regulating both known and unknown effectors. Here, we identify FARP2 as a 'RIPR' motif-dependent partner and substrate of aPKCι that is required for efficient polarisation and junction formation. Binding is conferred by a FERM/FA domain-kinase domain interaction and detachment promoted by aPKCι-dependent phosphorylation. FARP2 is shown to promote GTP loading of Cdc42, which is consistent with it being involved in upstream regulation of the polarising PAR6-aPKCι complex. However, we show that aPKCι acts to promote the localised activity of FARP2 through phosphorylation. We conclude that this aPKCι-FARP2 complex formation acts as a positive feedback control to drive polarisation through aPKCι and other Cdc42 effectors.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Ahmed Elbediwy
- Epithelial Biology Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Yixiao Zhang
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Mathias Cobbaut
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Philippe Riou
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Ray S Tan
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Selene K Roberts
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Chris Tynan
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Roger George
- Structural Biology Team, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Svend Kjaer
- Structural Biology Team, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Barry J Thompson
- Epithelial Biology Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Neil Q McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NE1 1AT, UK
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London SE1 1UL, UK
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Martin-Fernandez ML, Clarke DT, Roberts SK, Zanetti-Domingues LC, Gervasio FL. Structure and Dynamics of the EGF Receptor as Revealed by Experiments and Simulations and Its Relevance to Non-Small Cell Lung Cancer. Cells 2019; 8:E316. [PMID: 30959819 PMCID: PMC6523254 DOI: 10.3390/cells8040316] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/29/2019] [Accepted: 03/30/2019] [Indexed: 12/25/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is historically the prototypical receptor tyrosine kinase, being the first cloned and the first where the importance of ligand-induced dimer activation was ascertained. However, many years of structure determination has shown that EGFR is not completely understood. One challenge is that the many structure fragments stored at the PDB only provide a partial view because full-length proteins are flexible entities and dynamics play a key role in their functionality. Another challenge is the shortage of high-resolution data on functionally important higher-order complexes. Still, the interest in the structure/function relationships of EGFR remains unabated because of the crucial role played by oncogenic EGFR mutants in driving non-small cell lung cancer (NSCLC). Despite targeted therapies against EGFR setting a milestone in the treatment of this disease, ubiquitous drug resistance inevitably emerges after one year or so of treatment. The magnitude of the challenge has inspired novel strategies. Among these, the combination of multi-disciplinary experiments and molecular dynamic (MD) simulations have been pivotal in revealing the basic nature of EGFR monomers, dimers and multimers, and the structure-function relationships that underpin the mechanisms by which EGFR dysregulation contributes to the onset of NSCLC and resistance to treatment.
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Affiliation(s)
- Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK.
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK.
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK.
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK.
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Roberts SK, Hirsch M, McStea A, Zanetti-Domingues LC, Clarke DT, Claus J, Parker PJ, Wang L, Martin-Fernandez AML. Cluster Analysis of Endogenous HER2 and HER3 Receptors in SKBR3 Cells. Bio Protoc 2018; 8:e3096. [PMID: 34532543 DOI: 10.21769/bioprotoc.3096] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 01/11/2023] Open
Abstract
The Human Epidermal Growth Factor Receptor (HER) family of receptor tyrosine kinases consists of four, single pass, transmembrane receptor homologs (HER1-4) that act to regulate many critical processes in normal and tumor cells. HER2 is overexpressed in many tumors, and the deregulated proliferation of cancerous cells is driven by cooperation with its preferred receptor partner, HER3. The assessment of the in-situ organization of tagged HER2 and HER3 using super-resolution microscopy reveals quantitative Single Molecule Localization Microscopy (SMLM) as an ideal bioanalytical tool to characterize receptor clusters. Clustering of receptors is an important regulatory mechanism to prime cells to respond to stimuli so, to understand these processes, it is necessary to measure parameters such as numbers of clusters, cluster radii and the number of localizations per cluster for different perturbations. Previously, Fluorescence Localization Imaging with Photobleaching (FLImP), another nanoscale, single-molecule technique, characterized the oligomerization state of HER1 [or Epidermal Growth Factor Receptors (EGFR)] in cell membranes. To achieve an unprecedented resolution (< 5 nm) for inter-molecular separations in EGFR oligomers using FLImP, very few receptors are tagged, and so this method is unsuitable for measurements of whole receptor populations in cancer cells where receptors are frequently upregulated. Here, in order to detect all receptors involved in cluster formation, we saturate endogenous HER2 and HER3 membrane receptors with ligands at a 1:1 dye to protein ratio, in the presence or absence of therapeutic drugs (lapatinib or bosutinib). This is performed in the commonly used breast cancer cell line model SKBR3 cells, where there are ~1.6 million HER2 receptors/cell and 10,000-40,000 HER3 receptors/cell. The basal state of these receptors is studied using HER2- or HER3-specific Affibodies, and likewise, the active state is probed using the natural HER3 ligand, Neuregulin-beta1 (NRGβ1). Stochastic Optical Reconstruction Microscopy (STORM), one form of SMLM, was used here to image cells, which were chemically fixed to minimize image blurring and provide data (x and y coordinates and standard deviation of the measured localizations) for cluster analysis. Further analysis can also determine proportions of receptor colocalizations. Our findings show that lapatinib-bound HER2, complexed with HER3 via a non-canonical kinase dimer structure, induces higher order oligomers. We hypothesized that nucleation of receptors creates signaling platforms that explain the counterintuitive, increase in cell proliferation upon ligand binding, in the presence of the HER2-inhibitor lapatinib.
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Affiliation(s)
- Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Alexandra McStea
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Jeroen Claus
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,School of Cancer and Pharmaceutical Sciences, New Hunt's House, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Lin Wang
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - And Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK.,School of Cancer and Pharmaceutical Sciences, New Hunt's House, King's College London, Guy's Campus, London, SE1 1UL, UK
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9
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Zanetti-Domingues LC, Korovesis D, Needham SR, Tynan CJ, Sagawa S, Roberts SK, Kuzmanic A, Ortiz-Zapater E, Jain P, Roovers RC, Lajevardipour A, van Bergen En Henegouwen PMP, Santis G, Clayton AHA, Clarke DT, Gervasio FL, Shan Y, Shaw DE, Rolfe DJ, Parker PJ, Martin-Fernandez ML. The architecture of EGFR's basal complexes reveals autoinhibition mechanisms in dimers and oligomers. Nat Commun 2018; 9:4325. [PMID: 30337523 PMCID: PMC6193980 DOI: 10.1038/s41467-018-06632-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 09/11/2018] [Indexed: 11/09/2022] Open
Abstract
Our current understanding of epidermal growth factor receptor (EGFR) autoinhibition is based on X-ray structural data of monomer and dimer receptor fragments and does not explain how mutations achieve ligand-independent phosphorylation. Using a repertoire of imaging technologies and simulations we reveal an extracellular head-to-head interaction through which ligand-free receptor polymer chains of various lengths assemble. The architecture of the head-to-head interaction prevents kinase-mediated dimerisation. The latter, afforded by mutation or intracellular treatments, splits the autoinhibited head-to-head polymers to form stalk-to-stalk flexible non-extended dimers structurally coupled across the plasma membrane to active asymmetric tyrosine kinase dimers, and extended dimers coupled to inactive symmetric kinase dimers. Contrary to the previously proposed main autoinhibitory function of the inactive symmetric kinase dimer, our data suggest that only dysregulated species bear populations of symmetric and asymmetric kinase dimers that coexist in equilibrium at the plasma membrane under the modulation of the C-terminal domain.
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Affiliation(s)
- Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | | | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Antonija Kuzmanic
- Department of Chemistry, Faculty of Maths & Physical Sciences, University College London, London, WC1H 0AJ, UK
| | - Elena Ortiz-Zapater
- Peter Gore Department of Immunobiology, School of Immunology & Microbial Sciences, Kings College London, London, SE1 9RT, UK
| | - Purvi Jain
- Division of Cell Biology, Science Faculty, Department of Biology, Utrecht University, Utrecht, 3584 CH, The Netherlands
| | - Rob C Roovers
- Merus, LSI, Yalelaan 62, 3584 CM, Utrecht, The Netherlands
| | - Alireza Lajevardipour
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia
| | | | - George Santis
- Peter Gore Department of Immunobiology, School of Immunology & Microbial Sciences, Kings College London, London, SE1 9RT, UK
| | - Andrew H A Clayton
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Francesco L Gervasio
- Department of Chemistry, Faculty of Maths & Physical Sciences, University College London, London, WC1H 0AJ, UK
| | - Yibing Shan
- D. E. Shaw Research, New York, NY, 10036, USA
| | - David E Shaw
- D. E. Shaw Research, New York, NY, 10036, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK
| | - Peter J Parker
- Protein Phosphorylation Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW 1 1AT, UK
- School of Cancer and Pharmaceutical Sciences, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford, OX11 0QX, UK.
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10
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Brown A, Hézode C, Zuckerman E, Foster GR, Zekry A, Roberts SK, Lahser F, Durkan C, Badshah C, Zhang B, Robertson M, Wahl J, Barr E, Haber B. Efficacy and safety of 12 weeks of elbasvir ± grazoprevir ± ribavirin in participants with hepatitis C virus genotype 2, 4, 5 or 6 infection: The C-SCAPE study. J Viral Hepat 2018; 25:457-464. [PMID: 29152828 DOI: 10.1111/jvh.12801] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 09/02/2017] [Indexed: 02/06/2023]
Abstract
People with hepatitis C virus (HCV) infection other than genotype 1 represent a heterogeneous group. The aim of the phase 2 C-SCAPE study was to evaluate elbasvir/grazoprevir (EBR/GZR), with or without ribavirin (RBV), in participants with HCV genotype 2, 4, 5 or 6 infection. This was a part randomised, open-label, parallel-group study (NCT01932762; PN047-03) of treatment-naive, noncirrhotic participants. Participants with HCV genotype 2 infection received GZR 100 mg + RBV ± EBR 50 mg for 12 weeks and those with genotype 4, 5 or 6 infection were randomized to receive EBR/GZR ± RBV for 12 weeks. The primary endpoint was sustained virological response 12 weeks after completion of treatment (SVR12; HCV RNA <25 IU/mL). Among participants with genotype 2 infection, SVR12 was achieved by 80% (24/30) of those receiving EBR/GZR + RBV and 73% (19/26) of those receiving GZR + RBV. SVR rates were high in participants with HCV genotype 4 infection receiving EBR/GZR with and without RBV (100% [10/10] and 90% [9/10]; respectively). In contrast, the addition of RBV to EBR/GZR appeared to increase SVR12 in participants with genotype 5 infection (EBR/GZR, 25%; EBR/GZR + RBV 100% [4/4]). In participants with genotype 6 infection, SVR12 was 75% (3/4) in both those receiving EBR/GZR and those receiving EBR/GZR + RBV. The safety profile was similar across treatment arms, with adverse events tending to occur more frequently among participants receiving RBV. In conclusion, these data support the inclusion of participants with genotype 4 or 6 infection in the EBR/GZR phase 3 studies. EBR/GZR ± RBV was unsatisfactory for participants with genotype 2 or 5 infection.
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Affiliation(s)
- A Brown
- Imperial College Healthcare NHS Trust, London, UK
| | - C Hézode
- Henri Mondor Hospital, University of Paris-Est, Creteil, France
| | - E Zuckerman
- Liver Unit, Carmel Medical Center Technion Faculty of Medicine, Haifa, Israel
| | - G R Foster
- Liver Unit, Queen Mary University of London, London, UK
| | - A Zekry
- St George Hospital Clinical School, Inflammation and Infection Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - S K Roberts
- The Alfred Hospital, Melbourne, VIC, Australia
| | - F Lahser
- Merck & Co., Inc., Kenilworth, NJ, USA
| | - C Durkan
- Merck & Co., Inc., Kenilworth, NJ, USA
| | - C Badshah
- Merck & Co., Inc., Kenilworth, NJ, USA
| | - B Zhang
- Merck & Co., Inc., Kenilworth, NJ, USA
| | | | - J Wahl
- Merck & Co., Inc., Kenilworth, NJ, USA
| | - E Barr
- Merck & Co., Inc., Kenilworth, NJ, USA
| | - B Haber
- Merck & Co., Inc., Kenilworth, NJ, USA
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11
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Martin-Fernandez ML, Zanetti-Domingues LC, Korovesis D, Needham SR, Tynan CJ, Roberts SK, Clarke DT, Rolfe DJ, Parker PJ. Fluorescence Localisation Imaging with Photobleaching at 5 nm Resolution Reveals the Architecture of Basal EGFR Complexes and Mechanisms of Autoinhibition and Activation. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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12
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McCaughan GW, Thwaites PA, Roberts SK, Strasser SI, Mitchell J, Morales B, Mason S, Gow P, Wigg A, Tallis C, Jeffrey G, George J, Thompson AJ, Parker FC, Angus PW. Sofosbuvir and daclatasvir therapy in patients with hepatitis C-related advanced decompensated liver disease (MELD ≥ 15). Aliment Pharmacol Ther 2018; 47:401-411. [PMID: 29205432 DOI: 10.1111/apt.14404] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/14/2017] [Accepted: 10/11/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Antiviral therapy for hepatitis C has the potential to improve liver function in patients with decompensated cirrhosis. AIMS To examine the virological response and effect of viral clearance in patients with decompensated hepatitis C cirrhosis all with MELD scores ≥15 following sofosbuvir/daclatasvir ± ribavirin. METHODS We prospectively collected data on patients who commenced sofosbuvir/daclatasvir for 24-weeks under the Australian patient supply program (TOSCAR) and analysed outcomes including sustained viral response at 12 weeks (SVR12), death and transplant. RESULTS 108 patients (M/F, 79/29; median age 56years; Child-Pugh 10; MELD 16; genotype 1/3, 55/47) received sofosbuvir/daclatasvir and two also received ribavirin. On intention-to-treat, the SVR12 rate was 70% (76/108). Seventy-eight patients completed 24-weeks therapy. SVR12 was achieved in 56 of these patients on per-protocol-analysis (76%). SVR12 was 80% in genotype 1 compared to 69% in genotype 3. Thirty patients failed to complete therapy. In patients achieving SVR12, median MELD and Child-Pugh fell from 16(IQR15-17) to 14(12-17) and 10(9-11) to 8(7-9), respectively (P<.001). In those who died, MELD increased from 16 to 23 at death (P=.036). Patients who required transplantation had a significantly higher baseline MELD (20) compared to those patients completing treatment (16) (P=.0010). The odds ratio for transplant in patients with baseline MELD ≥20 was 13.8(95%CI 2.78-69.04). CONCLUSIONS SVR12 rates with sofosbuvir/daclatasvir in advanced liver disease are lower than in compensated disease. Although treatment improves MELD and Child-Pugh in most patients, a significant proportion will die or require transplantation. In those with MELD ≥20, it may be better to delay treatment until post-transplant.
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Affiliation(s)
- G W McCaughan
- Australian National Liver Transplant Unit, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - P A Thwaites
- Victorian Liver Transplant Unit, Austin Health, Heidelberg, Vic., Australia
| | - S K Roberts
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Vic., Australia
| | - S I Strasser
- Australian National Liver Transplant Unit, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - J Mitchell
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Vic., Australia
| | - B Morales
- Victorian Liver Transplant Unit, Austin Health, Heidelberg, Vic., Australia
| | - S Mason
- Australian National Liver Transplant Unit, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - P Gow
- Victorian Liver Transplant Unit, Austin Health, Heidelberg, Vic., Australia
| | - A Wigg
- South Australian Liver Transplant Unit, Flinders Medical Centre, Bedford Park, SA, Australia
| | - C Tallis
- Queensland Liver Transplant Unit, Princess Alexandra Hospital, Woolloongabba, Qld, Australia
| | - G Jeffrey
- Western Australian Liver Transplant Unit, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | - J George
- Department of Gastroenterology and Hepatology, Westmead Hospital, Westmead, NSW, Australia
| | - A J Thompson
- St Vincent's Hospital, University of Melbourne, Melbourne, Vic., Australia
| | - F C Parker
- Victorian Liver Transplant Unit, Austin Health, Heidelberg, Vic., Australia
| | - P W Angus
- Victorian Liver Transplant Unit, Austin Health, Heidelberg, Vic., Australia
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13
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Ooi GJ, Mgaieth S, Eslick GD, Burton PR, Kemp WW, Roberts SK, Brown WA. Systematic review and meta-analysis: non-invasive detection of non-alcoholic fatty liver disease related fibrosis in the obese. Obes Rev 2018; 19:281-294. [PMID: 29119725 DOI: 10.1111/obr.12628] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 09/11/2017] [Accepted: 09/15/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a significant disease burden in obesity. Liver fibrosis is an important prognostic factor in NAFLD, and detection is vital. The pathophysiological changes of obesity can alter the accuracy of non-invasive NAFLD tests. We aimed to review current evidence for common non-invasive tests for NAFLD-related fibrosis in obesity. METHODS We systematically searched for studies assessing the diagnostic accuracy of 11 biomarker panels and elastography techniques for NAFLD-related fibrosis in obesity. Meta-analyses were performed where possible. RESULTS Thirty-eight studies were identified assessing the selected tests in obese populations. Simple biomarker panels (e.g. NAFLD fibrosis score) were the most validated. Evidence showed better accuracy of complex biomarker panels (NAFLD fibrosis score: summary receiver operator characteristic [SROC] 0.795-0.813 vs. enhanced liver fibrosis: SROC 0.962); however, these were poorly validated in obesity. Elastography techniques were better studied and had high diagnostic accuracy (transient elastography: SROC 0.859; magnetic resonance elastography: SROC 0.965) but were limited by BMI-dependent failure. Limited evidence was found to validate the accuracy of any test in exclusively obese populations. CONCLUSION In obese subjects, complex biomarker panels and elastography have been reasonable to good accuracy for NAFLD-related fibrosis; however, these methods have not been well validated. Further study in this high-risk population is needed.
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Affiliation(s)
- G J Ooi
- Centre for Obesity Research and Education, Monash University, Melbourne, Australia.,Department of Surgery, The Alfred Hospital, Melbourne, Australia
| | - S Mgaieth
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Australia.,Department of Gastroenterology, Royal Melbourne Hospital, Melbourne, Australia
| | - G D Eslick
- The Whiteley-Martin Research Centre, Discipline of Surgery, The University of Sydney, Nepean Hospital, Penrith, Australia
| | - P R Burton
- Centre for Obesity Research and Education, Monash University, Melbourne, Australia.,Department of Surgery, The Alfred Hospital, Melbourne, Australia
| | - W W Kemp
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Australia
| | - S K Roberts
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Australia
| | - W A Brown
- Centre for Obesity Research and Education, Monash University, Melbourne, Australia.,Department of Surgery, The Alfred Hospital, Melbourne, Australia
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14
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Younossi ZM, Stepanova M, Jacobson IM, Asselah T, Gane EJ, Lawitz E, Foster GR, Roberts SK, Thompson AJ, Willems BE, Welzel TM, Pearlman B, Younossi I, Racila A, Henry L. Sofosbuvir and velpatasvir with or without voxilaprevir in direct-acting antiviral-naïve chronic hepatitis C: patient-reported outcomes from POLARIS 2 and 3. Aliment Pharmacol Ther 2018; 47:259-267. [PMID: 29181842 DOI: 10.1111/apt.14423] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 09/28/2017] [Accepted: 10/28/2017] [Indexed: 12/17/2022]
Abstract
BACKGROUND Chronic hepatitis C infection leads to impairment of patient-reported outcomes (PROs). Treatment with direct-acting antiviral regimens results in short- and long-term improvement of these outcomes. AIM To assess PROs in patients treated with a newly developed direct-acting antiviral, a fixed-dose combination of sofosbuvir/velpatasvir (SOF/VEL) with/without voxilaprevir (VOX). METHODS The PRO data were collected from participants of POLARIS-2 and POLARIS-3 clinical trials (DAA-naïve, all HCV genotypes). Participants self-administered SF-36v2, FACIT-F, CLDQ-HCV and WPAI:SHP instruments at baseline, during treatment, and in follow-up. RESULTS Of 1160 patients, 611 received SOF/VEL/VOX and 549 received SOF/VEL (52.8 ± 11.0 years, 55.9% male, 75.4% treatment-naïve, 33.9% cirrhotic). The sustained viral response at 12 weeks (SVR12) rates were 95%-98%. During treatment, improvements in most PRO scores were significant (all but one P < .01) and ranged from, on average, +2.3 to +15.0 points (on a 0-100 scale) by the end of treatment. These improvements were similar between SOF/VEL/VOX and SOF/VEL arms (all P > .05). After treatment discontinuation, patients treated with both regimens achieved significant and clinically meaningful PRO gains (+2.7 to +16.7 by post-treatment week 12, +3.9 to +20.1 by post-treatment week 24; all but one P < .001). Multivariate analysis showed that depression, anxiety and cirrhosis were the most consistent independent predictors of PRO impairment while no association of PROs with the treatment regimen choice was found (all P > .05). CONCLUSIONS The pan-genotypic regimens with SOF/VEL with or without VOX not only have excellent efficacy and safety, but also significantly positively impact patients' experience both during treatment and after achieving sustained virologic response in DAA-naïve patients with HCV.
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15
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Britto K, Cheung W, Cameron R, Roberts SK, Kemp W. Hepatobiliary and Pancreatic: Rare vascular tumor following treatment for hepatitis C with direct-acting antivirals. J Gastroenterol Hepatol 2017; 32:1912. [PMID: 28771829 DOI: 10.1111/jgh.13916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Affiliation(s)
- K Britto
- Department of Gastroenterology and Hepatology, Alfred Hospital, Melbourne, Victoria, Australia
| | - W Cheung
- Department of Radiology, Alfred Hospital, Melbourne, Victoria, Australia
| | - R Cameron
- Department of Anatomical Pathology, Alfred Hospital, Melbourne, Victoria, Australia
| | - S K Roberts
- Department of Gastroenterology and Hepatology, Alfred Hospital, Melbourne, Victoria, Australia
| | - W Kemp
- Department of Gastroenterology and Hepatology, Alfred Hospital, Melbourne, Victoria, Australia
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16
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Wedemeyer H, Craxí A, Zuckerman E, Dieterich D, Flisiak R, Roberts SK, Pangerl A, Zhang Z, Martinez M, Bao Y, Calleja JL. Real-world effectiveness of ombitasvir/paritaprevir/ritonavir±dasabuvir±ribavirin in patients with hepatitis C virus genotype 1 or 4 infection: A meta-analysis. J Viral Hepat 2017; 24:936-943. [PMID: 28480525 DOI: 10.1111/jvh.12722] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/20/2017] [Indexed: 12/13/2022]
Abstract
UNLABELLED The direct-acting antiviral regimen of ombitasvir (OBV)/paritaprevir (PTV)/ritonavir (r)±dasabuvir (DSV)±ribavirin (RBV) demonstrated high rates of sustained viral response at post-treatment week 12 (SVR12) in clinical trials for treatment of hepatitis C virus (HCV) genotypes (GT) 1 and 4. To confirm the effectiveness of this regimen in the real world, we conducted meta-analyses of published literature on 30 April 2016. Freeman-Tukey transformation determined the SVR rate within GTs 1a, 1b and 4, as well as specific SVR rates by cirrhosis or prior treatment experience status. Rates of virologic relapse, hepatic decompensation, drug discontinuation and serious adverse events were also analysed. In total, 20 cohorts across 12 countries were identified, totalling 5158 patients. The overall SVR12 rates were 96.8% (95% CI 95.8-97.7) for GT1 and 98.9% (95% CI 94.2-100) for GT4. For GT1a patients, the SVR rates were 94% and 97% for those with or without cirrhosis, and 94% overall. For GT1b patients, the SVR rates were 98% and 99% for those with or without cirrhosis, and 98% overall. The virologic relapse rate of GT1 patients was 1.3%, across 3524 patients in nine studies that reported this parameter. The rate of hepatic decompensation was less than 1% across five studies, including 3440 patients, 70% of which had cirrhosis. CONCLUSIONS Real-world SVR12 rates for OBV/PTV/r±DSV±RBV were consistently high across HCV GT1 and four irrespective of cirrhosis status or prior HCV treatment experience, confirming effectiveness within a diverse patient population across multiple cohorts and countries.
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Affiliation(s)
- H Wedemeyer
- Medizinische Hochschule Hannover, Hannover, Germany
| | - A Craxí
- AOU Policlinico "P Giaccone" Dip Di Gastroenterologia ed Epatologia DBMIS, Palermo, Italy
| | - E Zuckerman
- Carmel Medical Center Liver Institute, Haifa, Israel
| | | | - R Flisiak
- Klinika Chorób Zakaznych i Hepatologii UM w Bialymstoku, Bialystok, Poland
| | - S K Roberts
- Alfred Hospital and Monash University, Melbourne, Australia
| | | | - Z Zhang
- AbbVie Inc., North Chicago, IL, USA
| | | | - Y Bao
- AbbVie Inc., North Chicago, IL, USA
| | - J-L Calleja
- Hospital Universitario Puerta de Hierro, Universidad Autonoma de Madrid, Spain
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17
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Mgaieth S, Kemp W, Gow P, Fink M, Lubel J, Nicoll A, Gazzola A, Hong T, Ryan M, Knight V, Dev AT, Sood S, Bell S, Paul E, Roberts SK. Impact of viral hepatitis aetiology on survival outcomes in hepatocellular carcinoma: A large multicentre cohort study. J Viral Hepat 2017; 24:982-989. [PMID: 28414893 DOI: 10.1111/jvh.12717] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 02/27/2017] [Indexed: 12/15/2022]
Abstract
While HBV and HCV are risk factors for HCC, uncertainty exists as to whether these viral infections have prognostic significance in HCC. Thus, we compared the overall survival of patients with HBV, HCV and nonviral HCC, and evaluated whether the presence of HBV and HCV predicts patient outcomes. We conducted a multicentre study of HCC cases diagnosed at six Melbourne tertiary hospitals between Jan 2000-Dec 2014. Patient demographics, liver disease and tumour characteristics and patient outcomes were obtained from hospital databases, computer records and the Victorian Death Registry. Survival outcomes were compared between HBV, HCV and nonviral hepatitis cases and predictors of survival determined using Cox proportional hazards regression. There were 1436 new HCC cases identified including 776 due to viral hepatitis (HBV 235, HCV 511, HBV-HCV 30) and 660 from nonviral causes. The median survival of HBV, HCV and nonviral HCC patients was 59.1, 28.4 and 20.9 months, respectively (P<.0001). On multivariate analysis, independent risk factors for survival included HCC aetiology, gender, BCLC stage, serum AFP, total number and size of lesions, and serum creatinine and albumin. After adjusting for these and method of detection, HBV remained an independent predictor of improved overall survival when compared to both nonviral (HR 0.60%, 95% CI 0.35-0.98; P=.03) and HCV-related HCC (HR 0.51%, 95% CI 0.30-0.85; P=.01). In this large multicentre study, HBV is independently associated with improved overall survival compared with HCV and nonviral-related HCC. Further studies are needed to determine the underlying factor(s) responsible.
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Affiliation(s)
- S Mgaieth
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
| | - W Kemp
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
| | - P Gow
- Department of Gastroenterology, Austin Hospital, Heidelberg, Vic., Australia
| | - M Fink
- Department of Surgery, Austin Hospital, Heidelberg, Vic., Australia
| | - J Lubel
- Department of Gastroenterology, Box Hill Hospital, Box Hill, Vic., Australia
| | - A Nicoll
- Department of Gastroenterology, Box Hill Hospital, Box Hill, Vic., Australia.,Department of Gastroenterology, Royal Melbourne Hospital, Parkville, Vic., Australia
| | - A Gazzola
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
| | - T Hong
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Vic., Australia
| | - M Ryan
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Vic., Australia
| | - V Knight
- Department of Gastroenterology, Monash Medical Centre, Clayton, Vic., Australia
| | - A T Dev
- Department of Gastroenterology, Monash Medical Centre, Clayton, Vic., Australia
| | - S Sood
- Department of Gastroenterology, Royal Melbourne Hospital, Parkville, Vic., Australia
| | - S Bell
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Vic., Australia
| | - E Paul
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Vic., Australia
| | - S K Roberts
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
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18
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Needham SR, Roberts SK, Arkhipov A, Mysore VP, Tynan CJ, Zanetti-Domingues LC, Kim ET, Losasso V, Korovesis D, Hirsch M, Rolfe DJ, Clarke DT, Winn MD, Lajevardipour A, Clayton AHA, Pike LJ, Perani M, Parker PJ, Shan Y, Shaw DE, Martin-Fernandez ML. EGFR oligomerization organizes kinase-active dimers into competent signalling platforms. Nat Commun 2016; 7:13307. [PMID: 27796308 PMCID: PMC5095584 DOI: 10.1038/ncomms13307] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 09/20/2016] [Indexed: 12/19/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) signalling is activated by ligand-induced receptor dimerization. Notably, ligand binding also induces EGFR oligomerization, but the structures and functions of the oligomers are poorly understood. Here, we use fluorophore localization imaging with photobleaching to probe the structure of EGFR oligomers. We find that at physiological epidermal growth factor (EGF) concentrations, EGFR assembles into oligomers, as indicated by pairwise distances of receptor-bound fluorophore-conjugated EGF ligands. The pairwise ligand distances correspond well with the predictions of our structural model of the oligomers constructed from molecular dynamics simulations. The model suggests that oligomerization is mediated extracellularly by unoccupied ligand-binding sites and that oligomerization organizes kinase-active dimers in ways optimal for auto-phosphorylation in trans between neighbouring dimers. We argue that ligand-induced oligomerization is essential to the regulation of EGFR signalling. Epidermal growth factor receptors have been shown to oligomerise upon binding to their cognate ligands. Here, the authors use biochemical, biophysical and cell biology techniques to analyse the structures of these oligomers, and argue that these formations are required for signalling.
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Affiliation(s)
- Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | | | | | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Eric T Kim
- D.E. Shaw Research, New York, New York 10036, USA
| | - Valeria Losasso
- Computational Science and Engineering Department, Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
| | - Martyn D Winn
- Computational Science and Engineering Department, Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK
| | - Alireza Lajevardipour
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Andrew H A Clayton
- Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Linda J Pike
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, Missouri 63110, USA
| | - Michela Perani
- Division of Cancer Studies, King's College London, Guy's Medical School Campus, London SE1 1UL, UK
| | - Peter J Parker
- Division of Cancer Studies, King's College London, Guy's Medical School Campus, London SE1 1UL, UK.,The Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Yibing Shan
- D.E. Shaw Research, New York, New York 10036, USA
| | - David E Shaw
- D.E. Shaw Research, New York, New York 10036, USA.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK
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19
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Majumdar A, Kitson MT, Roberts SK. Systematic review: current concepts and challenges for the direct-acting antiviral era in hepatitis C cirrhosis. Aliment Pharmacol Ther 2016; 43:1276-92. [PMID: 27087015 DOI: 10.1111/apt.13633] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/06/2015] [Accepted: 03/29/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND The burden of HCV cirrhosis is high and projected to increase significantly over the next decade. While interferon therapy is problematic in HCV cirrhosis, the era of direct-acting anti-viral (DAA) therapy provides effective treatment for patients with cirrhosis. AIM To systematically review the results of DAA therapy to date in patients with HCV cirrhosis, and highlight the ongoing challenges for DAA therapy in this population. METHODS A structured Medline search was conducted to obtain phase II and III HCV trials in patients with cirrhosis. Citations from review articles were cross-referenced and conference abstracts from EASL and AASLD liver meetings for the preceding 3 years were reviewed manually. Keywords used included hepatitis C, cirrhosis and the DAA's: sofosbuvir, ledipasvir, velpatasvir, grazoprevir, elbasvir, daclatasvir, beclabuvir, asunaprevir, simeprevir, paritaprevir, ombitasvir and dasabuvir. RESULTS Successful direct-acting anti-viral treatment is now possible in patients with HCV-related cirrhosis including those with liver decompensation with several regimens now offering sustained virological response (SVR) of 90-95%. Overall success rates in GT1 cirrhosis are excellent while GT3-infected patients with cirrhosis remain hard to cure. The pangenotypic combination of sofosbuvir and velpatasvir holds promise for GT3 cirrhosis achieving SVR of ~90%. CONCLUSIONS Potent DAA therapies provide much needed, safe and highly effective treatment options for persons with HCV cirrhosis including those previously deemed unsuitable for treatment. Combination therapy with two or more classes of drug is essential to achieve high efficacy and minimise viral resistance, with the role of ribavirin still under evaluation. However, several challenges remain including the hard-to-cure groups of GT3 cirrhosis and direct-acting anti-viral failures, and managing drug-drug interactions.
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Affiliation(s)
- A Majumdar
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia.,UCL Institute for Liver and Digestive Health and Sheila Sherlock Liver Centre Royal Free Hospital, London, UK
| | - M T Kitson
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
| | - S K Roberts
- Department of Gastroenterology, Alfred Hospital, Melbourne, Vic., Australia
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Tynan CJ, Lo Schiavo V, Zanetti-Domingues L, Needham SR, Roberts SK, Hirsch M, Rolfe DJ, Korovesis D, Clarke DT, Martin-Fernandez ML. A tale of the epidermal growth factor receptor: The quest for structural resolution on cells. Methods 2015; 95:86-93. [PMID: 26484734 DOI: 10.1016/j.ymeth.2015.10.009] [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] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 01/03/2023] Open
Abstract
The challenge of determining the architecture and geometry of oligomers of the epidermal growth factor receptor (EGFR) on the cell surface has been approached using a variety of biochemical and biophysical methods. This review is intended to provide a narrative of how key concepts in the field of EGFR research have evolved over the years, from the origins of the prevalent EGFR signalling dimer hypothesis through to the development and implementation of methods that are now challenging the conventional view. The synergy between X-ray crystallography and cellular fluorescence microscopy has become particularly important, precisely because the results from these two methods diverged and highlighted the complexity of the challenge. We illustrate how developments in super-resolution microscopy are now bridging this gap. Exciting times lie ahead where knowledge of the nature of the complexes can assist with the development of a new generation of anti-cancer drugs.
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Affiliation(s)
- Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Valentina Lo Schiavo
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Laura Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Dimitrios Korovesis
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - David T Clarke
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom.
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21
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Webb SED, Hirsch M, Needham SR, Coles BC, Scherer KM, Roberts SK, Zanetti-Domingues LC, Tynan CJ, Martin-Fernandez ML, Rolfe DJ. Nanometric molecular separation measurements by single molecule photobleaching. Methods 2015; 88:76-80. [PMID: 25980369 DOI: 10.1016/j.ymeth.2015.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/08/2015] [Accepted: 05/06/2015] [Indexed: 01/03/2023] Open
Abstract
Although considerable progress has been made in imaging distances in cells below the diffraction limit using FRET and super-resolution microscopy, methods for determining the separation of macromolecules in the 10-50 nm range have been elusive. We have developed fluorophore localisation imaging with photobleaching (FLImP), based on the quantised bleaching of individual protein-bound dye molecules, to quantitate the molecular separations in oligomers and nanoscale clusters. We demonstrate the benefits of using our method in studying the nanometric organisation of the epidermal growth factor receptor in cells.
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Affiliation(s)
- Stephen E D Webb
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Michael Hirsch
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Sarah R Needham
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Benjamin C Coles
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Kathrin M Scherer
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Selene K Roberts
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Laura C Zanetti-Domingues
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0FA, UK.
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Bruggmann P, Berg T, Øvrehus ALH, Moreno C, Brandão Mello CE, Roudot-Thoraval F, Marinho RT, Sherman M, Ryder SD, Sperl J, Akarca U, Balık I, Bihl F, Bilodeau M, Blasco AJ, Buti M, Calinas F, Calleja JL, Cheinquer H, Christensen PB, Clausen M, Coelho HSM, Cornberg M, Cramp ME, Dore GJ, Doss W, Duberg AS, El-Sayed MH, Ergör G, Esmat G, Estes C, Falconer K, Félix J, Ferraz MLG, Ferreira PR, Frankova S, García-Samaniego J, Gerstoft J, Giria JA, Gonçales FL, Gower E, Gschwantler M, Guimarães Pessôa M, Hézode C, Hofer H, Husa P, Idilman R, Kåberg M, Kaita KDE, Kautz A, Kaymakoglu S, Krajden M, Krarup H, Laleman W, Lavanchy D, Lázaro P, Marotta P, Mauss S, Mendes Correa MC, Müllhaupt B, Myers RP, Negro F, Nemecek V, Örmeci N, Parkes J, Peltekian KM, Ramji A, Razavi H, Reis N, Roberts SK, Rosenberg WM, Sarmento-Castro R, Sarrazin C, Semela D, Shiha GE, Sievert W, Stärkel P, Stauber RE, Thompson AJ, Urbanek P, van Thiel I, Van Vlierberghe H, Vandijck D, Vogel W, Waked I, Wedemeyer H, Weis N, Wiegand J, Yosry A, Zekry A, Van Damme P, Aleman S, Hindman SJ. Historical epidemiology of hepatitis C virus (HCV) in selected countries. J Viral Hepat 2014; 21 Suppl 1:5-33. [PMID: 24713004 DOI: 10.1111/jvh.12247] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic infection with hepatitis C virus (HCV) is a leading indicator for liver disease. New treatment options are becoming available, and there is a need to characterize the epidemiology and disease burden of HCV. Data for prevalence, viremia, genotype, diagnosis and treatment were obtained through literature searches and expert consensus for 16 countries. For some countries, data from centralized registries were used to estimate diagnosis and treatment rates. Data for the number of liver transplants and the proportion attributable to HCV were obtained from centralized databases. Viremic prevalence estimates varied widely between countries, ranging from 0.3% in Austria, England and Germany to 8.5% in Egypt. The largest viremic populations were in Egypt, with 6,358,000 cases in 2008 and Brazil with 2,106,000 cases in 2007. The age distribution of cases differed between countries. In most countries, prevalence rates were higher among males, reflecting higher rates of injection drug use. Diagnosis, treatment and transplant levels also differed considerably between countries. Reliable estimates characterizing HCV-infected populations are critical for addressing HCV-related morbidity and mortality. There is a need to quantify the burden of chronic HCV infection at the national level.
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Affiliation(s)
- P Bruggmann
- Arud Centres for Addiction Medicine, Zurich, Switzerland
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Razavi H, Waked I, Sarrazin C, Myers RP, Idilman R, Calinas F, Vogel W, Mendes Correa MC, Hézode C, Lázaro P, Akarca U, Aleman S, Balık I, Berg T, Bihl F, Bilodeau M, Blasco AJ, Brandão Mello CE, Bruggmann P, Buti M, Calleja JL, Cheinquer H, Christensen PB, Clausen M, Coelho HSM, Cramp ME, Dore GJ, Doss W, Duberg AS, El-Sayed MH, Ergör G, Esmat G, Falconer K, Félix J, Ferraz MLG, Ferreira PR, Frankova S, García-Samaniego J, Gerstoft J, Giria JA, Gonçales FL, Gower E, Gschwantler M, Guimarães Pessôa M, Hindman SJ, Hofer H, Husa P, Kåberg M, Kaita KDE, Kautz A, Kaymakoglu S, Krajden M, Krarup H, Laleman W, Lavanchy D, Marinho RT, Marotta P, Mauss S, Moreno C, Murphy K, Negro F, Nemecek V, Örmeci N, Øvrehus ALH, Parkes J, Pasini K, Peltekian KM, Ramji A, Reis N, Roberts SK, Rosenberg WM, Roudot-Thoraval F, Ryder SD, Sarmento-Castro R, Semela D, Sherman M, Shiha GE, Sievert W, Sperl J, Stärkel P, Stauber RE, Thompson AJ, Urbanek P, Van Damme P, van Thiel I, Van Vlierberghe H, Vandijck D, Wedemeyer H, Weis N, Wiegand J, Yosry A, Zekry A, Cornberg M, Müllhaupt B, Estes C. The present and future disease burden of hepatitis C virus (HCV) infection with today's treatment paradigm. J Viral Hepat 2014; 21 Suppl 1:34-59. [PMID: 24713005 DOI: 10.1111/jvh.12248] [Citation(s) in RCA: 275] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The disease burden of hepatitis C virus (HCV) is expected to increase as the infected population ages. A modelling approach was used to estimate the total number of viremic infections, diagnosed, treated and new infections in 2013. In addition, the model was used to estimate the change in the total number of HCV infections, the disease progression and mortality in 2013-2030. Finally, expert panel consensus was used to capture current treatment practices in each country. Using today's treatment paradigm, the total number of HCV infections is projected to decline or remain flat in all countries studied. However, in the same time period, the number of individuals with late-stage liver disease is projected to increase. This study concluded that the current treatment rate and efficacy are not sufficient to manage the disease burden of HCV. Thus, alternative strategies are required to keep the number of HCV individuals with advanced liver disease and liver-related deaths from increasing.
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Affiliation(s)
- H Razavi
- Center for Disease Analysis, Louisville, Colorado, USA
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Wedemeyer H, Duberg AS, Buti M, Rosenberg WM, Frankova S, Esmat G, Örmeci N, Van Vlierberghe H, Gschwantler M, Akarca U, Aleman S, Balık I, Berg T, Bihl F, Bilodeau M, Blasco AJ, Brandão Mello CE, Bruggmann P, Calinas F, Calleja JL, Cheinquer H, Christensen PB, Clausen M, Coelho HSM, Cornberg M, Cramp ME, Dore GJ, Doss W, El-Sayed MH, Ergör G, Estes C, Falconer K, Félix J, Ferraz MLG, Ferreira PR, García-Samaniego J, Gerstoft J, Giria JA, Gonçales FL, Guimarães Pessôa M, Hézode C, Hindman SJ, Hofer H, Husa P, Idilman R, Kåberg M, Kaita KDE, Kautz A, Kaymakoglu S, Krajden M, Krarup H, Laleman W, Lavanchy D, Lázaro P, Marinho RT, Marotta P, Mauss S, Mendes Correa MC, Moreno C, Müllhaupt B, Myers RP, Nemecek V, Øvrehus ALH, Parkes J, Peltekian KM, Ramji A, Razavi H, Reis N, Roberts SK, Roudot-Thoraval F, Ryder SD, Sarmento-Castro R, Sarrazin C, Semela D, Sherman M, Shiha GE, Sperl J, Stärkel P, Stauber RE, Thompson AJ, Urbanek P, Van Damme P, van Thiel I, Vandijck D, Vogel W, Waked I, Weis N, Wiegand J, Yosry A, Zekry A, Negro F, Sievert W, Gower E. Strategies to manage hepatitis C virus (HCV) disease burden. J Viral Hepat 2014; 21 Suppl 1:60-89. [PMID: 24713006 DOI: 10.1111/jvh.12249] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The number of hepatitis C virus (HCV) infections is projected to decline while those with advanced liver disease will increase. A modeling approach was used to forecast two treatment scenarios: (i) the impact of increased treatment efficacy while keeping the number of treated patients constant and (ii) increasing efficacy and treatment rate. This analysis suggests that successful diagnosis and treatment of a small proportion of patients can contribute significantly to the reduction of disease burden in the countries studied. The largest reduction in HCV-related morbidity and mortality occurs when increased treatment is combined with higher efficacy therapies, generally in combination with increased diagnosis. With a treatment rate of approximately 10%, this analysis suggests it is possible to achieve elimination of HCV (defined as a >90% decline in total infections by 2030). However, for most countries presented, this will require a 3-5 fold increase in diagnosis and/or treatment. Thus, building the public health and clinical provider capacity for improved diagnosis and treatment will be critical.
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Affiliation(s)
- H Wedemeyer
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
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Duffy P, Magno LM, Yadav RB, Roberts SK, Ward AD, Botchway SW, Colavita PE, Quinn SJ. Incandescent porous carbon microspheres to light up cells: solution phenomena and cellular uptake. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm14303d] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Berzsenyi MD, Roberts SK, Preiss S, Woollard DJ, Beard MR, Skinner NA, Bowden DS, Visvanathan K. Hepatic TLR2 & TLR4 expression correlates with hepatic inflammation and TNF-α in HCV & HCV/HIV infection. J Viral Hepat 2011; 18:852-60. [PMID: 21050341 DOI: 10.1111/j.1365-2893.2010.01390.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Signalling activated by Toll-like receptors (TLRs) can result in the production of tumour necrosis factor alpha (TNF-α) which is implicated in hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection. No study has examined or compared hepatic expression of TLRs in both HCV and HCV/HIV. Liver and peripheral blood mononuclear cells (PBMCs) were obtained from HCV & HCV/HIV-infected patients and PBMCs from HIV-infected patients. Liver RNA was analysed by microarray and reverse transcription quantitative PCR (RT-qPCR). PBMCs were analysed by flow cytometry. Associations with hepatic histology and infection type were sought. Forty-six HCV, 20 HIV and 27 HCV/HIV-infected patients were recruited. Increasing Metavir inflammatory activity score was associated with increased hepatic TLR mRNA by RT-qPCR: TLR2 (P ≤ 0.001), TLR4 (P = 0.008) and TNF-α (P ≤ 0.001). A high degree of correlation was seen between hepatic mRNA expression of TNF-αvs TLR2 (r(2) = 0.66, P < 0.0001) and TLR4 (r(2) = 0.60, P < 0.0001). No differences in TLR gene or protein expression was observed between HCV, HCV/HIV- or HIV-infected groups. Hepatic TLR2, TLR4 and TNF-α mRNA are associated with hepatic inflammation in both HCV and HCV/HIV infection. High correlation between TNF-α and TLR2/TLR4 suggests a role for the innate immune response in TNF-α production. Activation of the innate immune response appears to be independent of infection type.
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Affiliation(s)
- M D Berzsenyi
- Department of Gastroenterology, Alfred Hospital, Prahran, Victoria, Australia.
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Clarke DT, Botchway SW, Coles BC, Needham SR, Roberts SK, Rolfe DJ, Tynan CJ, Ward AD, Webb SED, Yadav R, Zanetti-Domingues L, Martin-Fernandez ML. Optics clustered to output unique solutions: a multi-laser facility for combined single molecule and ensemble microscopy. Rev Sci Instrum 2011; 82:093705. [PMID: 21974592 DOI: 10.1063/1.3635536] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Optics clustered to output unique solutions (OCTOPUS) is a microscopy platform that combines single molecule and ensemble imaging methodologies. A novel aspect of OCTOPUS is its laser excitation system, which consists of a central core of interlocked continuous wave and pulsed laser sources, launched into optical fibres and linked via laser combiners. Fibres are plugged into wall-mounted patch panels that reach microscopy end-stations in adjacent rooms. This allows multiple tailor-made combinations of laser colours and time characteristics to be shared by different end-stations minimising the need for laser duplications. This setup brings significant benefits in terms of cost effectiveness, ease of operation, and user safety. The modular nature of OCTOPUS also facilitates the addition of new techniques as required, allowing the use of existing lasers in new microscopes while retaining the ability to run the established parts of the facility. To date, techniques interlinked are multi-photon/multicolour confocal fluorescence lifetime imaging for several modalities of fluorescence resonance energy transfer (FRET) and time-resolved anisotropy, total internal reflection fluorescence, single molecule imaging of single pair FRET, single molecule fluorescence polarisation, particle tracking, and optical tweezers. Here, we use a well-studied system, the epidermal growth factor receptor network, to illustrate how OCTOPUS can aid in the investigation of complex biological phenomena.
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Affiliation(s)
- David T Clarke
- Science and Technology Facilities Council, Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxford OX11 0FA, United Kingdom
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Patterson SJ, George J, Strasser SI, Lee AU, Sievert W, Nicoll AJ, Desmond PV, Roberts SK, Locarnini S, Bowden S, Angus PW. Tenofovir disoproxil fumarate rescue therapy following failure of both lamivudine and adefovir dipivoxil in chronic hepatitis B. Gut 2011. [PMID: 21036792 DOI: 10.1136/gut] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To determine the efficacy of tenofovir disoproxil fumarate (TDF) in adults with chronic hepatitis B virus (HBV) infection who had previously failed lamivudine (LAM) and had significant viral replication (HBV DNA >10⁵ copies/ml if HBeAg positive, > 10⁴ copies/ml if HBeAg negative) despite at least 24 weeks of treatment with adefovir dipivoxil (ADV). DESIGN A prospective open-label study of TDF 300 mg daily. Patients receiving combination ADV/LAM prior to baseline were switched to TDF/LAM. SETTING Multiple tertiary referral centres. METHODS Sixty patients were enrolled. The median age was 48.5 years (range 21e80), 46 (77%) were male and 40 (67%) were HBeAg positive. Thirty-eight patients (63%) were switched from ADV to TDF, the remainder from ADV/LAM to TDF/LAM. At baseline, substitutions conferring resistance to LAM or ADV were present in 20 patients (33%) and 17 patients (28%), respectively. The median baseline viral load was 5.33 log₁₀ IU/ml (range 2.81-8.04). Patients initially treated with TDF monotherapy with persistent viral replication at or after 24 weeks were switched to TDF/LAM. The main outcome measures were change in HBV viral load from baseline and percentage of patients achieving an undetectable viral load (<15 IU/ml). RESULTS Results are reported at 96 weeks of treatment. One patient discontinued TDF at 10 days due to rash. The time-weighted change in viral load from baseline to week 12 was -2.19 log10 IU/ml overall. The median change in HBV DNA from baseline to weeks 12, 24, 48 and 96 was -2.86, -3.23, -3.75 and -4.03 log₁₀ IU/ml, respectively. At 48 and 96 weeks, 27/59 (46%) and 38/59 (64%) patients achieved a HBV DNA <15 IU/ml. The response was independent of baseline LAM therapy or mutations conferring ADV resistance. CONCLUSIONS In heavily pretreated patients with a high rate of genotypic resistance, TDF retains significant activity against HBV although this appears diminished in comparison with studies of naïve patients.
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Affiliation(s)
- S J Patterson
- Liver Transplant Unit, Austin Health, Studley Road, Heidelberg, VIC 3084, Australia.
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Patterson SJ, George J, Strasser SI, Lee AU, Sievert W, Nicoll AJ, Desmond PV, Roberts SK, Locarnini S, Bowden S, Angus PW. Tenofovir disoproxil fumarate rescue therapy following failure of both lamivudine and adefovir dipivoxil in chronic hepatitis B. Gut 2011; 60:247-54. [PMID: 21036792 DOI: 10.1136/gut.2010.223206] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To determine the efficacy of tenofovir disoproxil fumarate (TDF) in adults with chronic hepatitis B virus (HBV) infection who had previously failed lamivudine (LAM) and had significant viral replication (HBV DNA >10⁵ copies/ml if HBeAg positive, > 10⁴ copies/ml if HBeAg negative) despite at least 24 weeks of treatment with adefovir dipivoxil (ADV). DESIGN A prospective open-label study of TDF 300 mg daily. Patients receiving combination ADV/LAM prior to baseline were switched to TDF/LAM. SETTING Multiple tertiary referral centres. METHODS Sixty patients were enrolled. The median age was 48.5 years (range 21e80), 46 (77%) were male and 40 (67%) were HBeAg positive. Thirty-eight patients (63%) were switched from ADV to TDF, the remainder from ADV/LAM to TDF/LAM. At baseline, substitutions conferring resistance to LAM or ADV were present in 20 patients (33%) and 17 patients (28%), respectively. The median baseline viral load was 5.33 log₁₀ IU/ml (range 2.81-8.04). Patients initially treated with TDF monotherapy with persistent viral replication at or after 24 weeks were switched to TDF/LAM. The main outcome measures were change in HBV viral load from baseline and percentage of patients achieving an undetectable viral load (<15 IU/ml). RESULTS Results are reported at 96 weeks of treatment. One patient discontinued TDF at 10 days due to rash. The time-weighted change in viral load from baseline to week 12 was -2.19 log10 IU/ml overall. The median change in HBV DNA from baseline to weeks 12, 24, 48 and 96 was -2.86, -3.23, -3.75 and -4.03 log₁₀ IU/ml, respectively. At 48 and 96 weeks, 27/59 (46%) and 38/59 (64%) patients achieved a HBV DNA <15 IU/ml. The response was independent of baseline LAM therapy or mutations conferring ADV resistance. CONCLUSIONS In heavily pretreated patients with a high rate of genotypic resistance, TDF retains significant activity against HBV although this appears diminished in comparison with studies of naïve patients.
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Affiliation(s)
- S J Patterson
- Liver Transplant Unit, Austin Health, Studley Road, Heidelberg, VIC 3084, Australia.
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Rabbitts JA, Strom NA, Sawyer JR, Curry TB, Dietz NM, Roberts SK, Kingsley-Berg SM, Charkoudian N. Influence of endogenous angiotensin II on control of sympathetic nerve activity in human dehydration. J Physiol 2009; 587:5441-9. [PMID: 19805740 DOI: 10.1113/jphysiol.2009.176693] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Arterial blood pressure can often fall too low during dehydration, leading to an increased incidence of orthostatic hypotension and syncope. Systemic sympathoexcitation and increases in volume regulatory hormones such as angiotensin II (AngII) may help to maintain arterial pressure in the face of decreased plasma volume. Our goals in the present study were to quantify muscle sympathetic nerve activity (MSNA) during dehydration (DEH), and to test the hypothesis that endogenous increases in AngII in DEH have a mechanistic role in DEH-associated sympathoexcitation. We studied 17 subjects on two separate study days: DEH induced by 24 h fluid restriction and a euhydrated (EUH) control day. MSNA was measured by microneurography at the peroneal nerve, and arterial blood pressure, electrocardiogram, and central venous pressure were also recorded continuously. Sequential nitroprusside and phenylephrine (modified Oxford test) were used to evaluate baroreflex control of MSNA. Losartan (angiotensin type 1 receptor (AT1) antagonist) was then administered and measurements were repeated. MSNA was elevated during DEH (42 +/- 5 vs. EUH: 32 +/- 4 bursts per 100 heartbeats, P = 0.02). Blockade of AT1 receptors partially reversed this change in MSNA during DEH while having no effect in the control EUH condition. The sensitivity of baroreflex control of MSNA was unchanged during DEH compared to EUH. We conclude that endogenous increases in AngII during DEH contribute to DEH-associated sympathoexcitation.
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Affiliation(s)
- J A Rabbitts
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA.
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Kästner J, Loeffler HH, Roberts SK, Martin-Fernandez ML, Winn MD. Ectodomain orientation, conformational plasticity and oligomerization of ErbB1 receptors investigated by molecular dynamics. J Struct Biol 2009; 167:117-28. [DOI: 10.1016/j.jsb.2009.04.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 03/21/2009] [Accepted: 04/21/2009] [Indexed: 02/01/2023]
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Webb SED, Rolfe DJ, Needham SR, Roberts SK, Clarke DT, McLachlan CI, Hobson MP, Martin-Fernandez ML. Simultaneous widefield single molecule orientation and FRET microscopy in cells. Opt Express 2008; 16:20258-20265. [PMID: 19065164 DOI: 10.1364/oe.16.020258] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We combine single molecule fluorescence orientation imaging with single-pair fluorescence resonance energy transfer microscopy, using a total internal reflection microscope. We show how angles and FRET efficiencies can be determined for membrane proteins at the single molecule level and provide data from the epidermal growth factor receptor system in cells.
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Affiliation(s)
- S E D Webb
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, UK.
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33
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Jones KL, Brown LE, Eriksson EMY, Ffrench RA, Latour PA, Loveland BE, Wall DM, Roberts SK, Jackson DC, Gowans EJ. Human dendritic cells pulsed with specific lipopeptides stimulate autologous antigen-specific T cells without the addition of exogenous maturation factors. J Viral Hepat 2008; 15:761-72. [PMID: 18637077 DOI: 10.1111/j.1365-2893.2008.01003.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Serum-free culture conditions to generate immature human monocyte-derived DC (Mo-DC) were optimized, and the parameters that influence their maturation after exposure to lipopeptides containing CD4(+) and CD8(+) T-cell epitopes were examined. The lipopeptides contained a single CD4(+) helper T-cell epitopes, one of a number of human leucocyte antigen (HLA)-A2-restricted cytotoxic T-cell epitope and the lipid Pam2Cys. To ensure complete maturation of the Mo-DC, we examined (i) the optimal lipopeptide concentration, (ii) the optimal Mo-DC density and (iii) the appropriate period of exposure of the Mo-DC to the lipopeptides. The results showed that a high dose of lipopeptide (30 microm) was no more efficient at upregulating maturation markers on Mo-DC than a low dose (6 microm). There was an inverse relationship between Mo-DC concentration and the mean fluorescence intensity of maturation markers. In addition, at the higher cell concentrations, the chemotactic capacity of the Mo-DC towards a cognate ligand, CCL21, was reduced. Thus, high cell concentrations during lipopeptide exposure were detrimental to Mo-DC maturation and function. The duration of exposure of Mo-DC to the lipopeptides had little effect on phenotype, although Mo-DC exposed to lipopeptides for 48 rather than 4 h showed an increased ability to stimulate autologous peripheral blood mononuclear cells to release interferon-gamma in the absence of exogenous maturation factors. These findings reveal conditions for generating mature antigen-loaded DC suitable for targeted immunotherapy.
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Affiliation(s)
- K L Jones
- Department of Immunology, Monash University, Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia
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Webb SE, Roberts SK, Needham SR, Tynan CJ, Rolfe DJ, Winn MD, Clarke DT, Barraclough R, Martin-Fernandez ML. Single-molecule imaging and fluorescence lifetime imaging microscopy show different structures for high- and low-affinity epidermal growth factor receptors in A431 cells. Biophys J 2007; 94:803-19. [PMID: 17890389 PMCID: PMC2186246 DOI: 10.1529/biophysj.107.112623] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Epidermal growth factor (EGF) receptor (EGFR) modulates mitosis and apoptosis through signaling by its high-affinity (HA) and low-affinity (LA) EGF-binding states. The prevailing model of EGFR activation-derived from x-ray crystallography-involves the transition from tethered ectodomain monomers to extended back-to-back dimers and cannot explain these EGFR affinities or their different functions. Here, we use single-molecule Förster resonant energy transfer analysis in combination with ensemble fluorescence lifetime imaging microscopy to investigate the three-dimensional architecture of HA and LA EGFR-EGF complexes in cells by measuring the inter-EGF distances within discrete EGF pairs and the vertical distance from EGF to the plasma membrane. Our results show that EGFR ectodomains form interfaces resulting in two inter-EGF distances ( approximately 8 nm and < 5.5 nm), different from the back-to-back EGFR ectodomain interface ( approximately 11 nm). Distance measurements from EGF to the plasma membrane show that HA EGFR ectodomains are oriented flat on the membrane, whereas LA ectodomains stand proud from it. Their flat orientation confers on HA EGFR ectodomains the exclusive ability to interact via asymmetric interfaces, head-to-head with respect to the EGF-binding site, whereas LA EGFRs must interact only side-by-side. Our results support a structural model in which asymmetric EGFR head-to-head interfaces may be relevant for HA EGFR oligomerization.
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Affiliation(s)
- Stephen E.D. Webb
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - Selene K. Roberts
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - Sarah R. Needham
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - Christopher J. Tynan
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
- Physics Department and Surface Science Research Centre, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Daniel J. Rolfe
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - Martyn D. Winn
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - David T. Clarke
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
| | - Roger Barraclough
- School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Marisa L. Martin-Fernandez
- Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD, United Kingdom
- Address reprint requests to Marisa L. Martin-Fernandez, STFC Daresbury Laboratory, Warrington WA4 4AD, UK. Tel.: 44-1925-603568; Fax: 44-1925-603124.
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Zeuzem S, Alberti A, Rosenberg W, Marcellin P, Diago M, Negro F, Prati D, Puoti C, Roberts SK, Shiffman ML. Review article: management of patients with chronic hepatitis C virus infection and "normal" alanine aminotransferase activity. Aliment Pharmacol Ther 2006; 24:1133-49. [PMID: 17014573 DOI: 10.1111/j.1365-2036.2006.03073.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [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: 12/22/2022]
Abstract
BACKGROUND Hepatitis C virus infection, a major cause of chronic liver disease, occurs with normal serum alanine aminotransferase activity in approximately 25% of patients. These patients have historically remained untreated but substantial evidence indicates liver damage, progression of disease and impaired quality of life in some individuals. AIM To review the current management of patients with chronic hepatitis C and normal alanine aminotransferase activity. METHODS This review represents the summary of discussions at a Clinical Workshop with a comprehensive literature searching of available databases (PubMed and Embase). RESULTS Current limits defining normal serum alanine aminotransferase activity are not representative of a "healthy" status. Most patients with hepatitis C and normal alanine aminotransferase levels have histologically proven liver damage that, although generally mild, may be significant (> or =F2) in up to 20% of patients and progresses at approximately 50% of the rate in patients with elevated alanine aminotransferase levels. Some patients have persistently normal alanine aminotransferase activity and may have a more benign outcome, but a significant proportion (> or =20%) experience periods of increased serum alanine aminotransferase activity which may be associated with enhanced disease progression. CONCLUSIONS A treatment approach that considers host and virus-related variables and optimizes patient and cost benefits may therefore provide more effective management of patients with chronic hepatitis C and normal alanine aminotransferase activity.
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Affiliation(s)
- S Zeuzem
- Department of Internal Medicine, , Saarland University Hospital, 66421 Homburg/Saar, Germany.
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Webb SED, Needham SR, Roberts SK, Martin-Fernandez ML. Multidimensional single-molecule imaging in live cells using total-internal-reflection fluorescence microscopy. Opt Lett 2006; 31:2157-9. [PMID: 16794711 DOI: 10.1364/ol.31.002157] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We have developed a wide-field total-internal-reflection fluorescence microscope capable of imaging single molecules in live cells, resolved in both wavelength and polarization. We show fluorescence resonance energy transfer between single pairs of fluorescent molecules bound to signaling receptors in the plasma membrane of live cells and demonstrate the importance of polarization discrimination in addition to wavelength separation.
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Affiliation(s)
- S E D Webb
- CCLRC Daresbury Laboratory, Warrington, UK.
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Desmond CP, Roberts SK, Dudley F, Mitchell J, Day C, Nguyen S, Pianko S. Sustained virological response rates and durability of the response to interferon-based therapies in hepatitis C patients treated in the clinical setting. J Viral Hepat 2006; 13:311-5. [PMID: 16637861 DOI: 10.1111/j.1365-2893.2005.00685.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [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: 12/09/2022]
Abstract
International controlled trials have demonstrated increasing sustained virological response (SVR) rates to interferon-based therapies in hepatitis-C-treated patients. Response rates of 6-20% in the era of interferon monotherapy are compared with 42-82% with pegylated interferon plus ribavirin. The virological durability of the SVR is unknown and the optimal follow-up for these patients is unclear. The aim of our study was to determine SVR rates and the durability of the response to interferon-based therapies in the clinical setting. From our database of 1540 hepatitis C patients, 344 treatment courses of at least 12 weeks duration were identified, including interferon monotherapy (175 patients), interferon plus ribavirin (96 patients) and peginterferon plus ribavirin (73 patients). Interferon monotherapy was associated with an SVR rate of 5% in 103 genotype 1 patients and 25% in 72 genotype 2/3 patients. Response rates were higher (P < 0.001) with interferon plus ribavirin-41% in 34 genotype 1 patients and 73% in 62 genotype 2/3 patients-and with peginterferon plus ribavirin-47% in 47 genotype 1 patients and 79% in 26 genotype 2/3 patients. Of 147 patients with an SVR, 146 (>99%) remained hepatitis C virus PCR negative during a mean 2.3 years (range 0.3-10.3) of follow-up. In conclusion, with advances in therapies, we are achieving higher response rates in hepatitis C patients treated in the clinical setting. We can now expect an SVR in over half of the treated patients. Importantly, the response is durable and medium and long-term follow-up of these patients are of low yield and largely unnecessary.
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Affiliation(s)
- C P Desmond
- Department of Gastroenterology, The Alfred Hospital, Melbourne, Vic., Australia.
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38
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Charkoudian N, Eisenach JH, Joyner MJ, Roberts SK, Wick DE. Interactions of plasma osmolality with arterial and central venous pressures in control of sympathetic activity and heart rate in humans. Am J Physiol Heart Circ Physiol 2005; 289:H2456-60. [PMID: 16199481 DOI: 10.1152/ajpheart.00601.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [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: 11/22/2022]
Abstract
Plasma osmolality alters control of sympathetic activity and heart rate in animal models; however, it is unknown whether physiological increases in plasma osmolality have such influences in humans and what effect concurrent changes in central venous and/or arterial pressures may have. We tested whether physiological increases in plasma osmolality (similar to those during exercise dehydration) alter control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in humans. We studied 17 healthy young adults (7 women, 10 men) at baseline and during arterial pressure (AP) transients induced by sequential injections of nitroprusside and phenylephrine, under three conditions: control (C), after 1 ml/kg intravenous hypertonic saline (HT1), and after 2 ml/kg hypertonic saline (HT2). We continuously measured HR, AP, central venous pressure (CVP; peripherally inserted central catheter) and MSNA (peroneal microneurography) in all conditions. Plasma osmolality increased from 287 +/- 1 mosmol/kg in C to 290 +/- 1 mosmol/kg in HT1 (P < 0.05) but did not increase further in HT2 (291 +/- 1 mosmol/kg; P > 0.05 vs. C). Mean AP and CVP were similar between C and HT1, but both increased slightly in HT2. HR increased slightly but significantly during both HT1 and HT2 vs. C (P < 0.05). Sensitivity of baroreflex control of MSNA was significantly increased vs. C in HT1 [-7.59 +/- 0.97 (HT1) vs. -5.85 +/- 0.63 (C) arbitrary units (au).beat(-1).mmHg(-1); P < 0.01] but was not different in HT2 (-6.55 +/- 0.94 au.beat(-1).mmHg(-1)). We conclude that physiological changes in plasma osmolality significantly alter control of MSNA and HR in humans, and that this influence can be modified by CVP and AP.
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Affiliation(s)
- N Charkoudian
- Dept. of Physiology and Biomedical Engineering, JO 4-184W, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
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Abstract
Abdominal pain related to exercise, often loosely referred to as 'stitch', is not uncommon, particularly among participants in sports that involve running. The cause of this typically transient pain is poorly understood with several aetiologies proposed including diaphragmatic ischaemia (1, 2). Other gastrointestinal symptoms that are common during prolonged or high-intensity exercise include nausea, diarrhoea and gastrointestinal bleeding (3, 4). These symptoms are also usually transient and are thought to protect against critical organ damage by promoting cessation of exercise. Decreased gastrointestinal blood flow, increased motility and altered neuroendocrine modulation are postulated disease mechanisms (3). We report here a case of an elite runner with exercise-related severe abdominal pain and diarrhoea related to compression of the coeliac axis by the median arcuate ligament. Complete symptom relief was achieved with surgical division of the constricting ligament. The clinical characteristics and pathogenesis of coeliac axis compression syndrome are discussed.
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Affiliation(s)
- C P Desmond
- Dept of Gastroenterology, The Alfred Hospital, Melbourne, Victoria, Australia
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Bundey S, Raymond S, Dean P, Roberts SK, Dillon RJ, Charnley AK. Eicosanoid involvement in the regulation of behavioral fever in the desert locust, Schistocerca gregaria. Arch Insect Biochem Physiol 2003; 52:183-192. [PMID: 12655606 DOI: 10.1002/arch.10081] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The desert locust Schistocerca gregaria behaviorally thermoregulates in order to try and maintain a favoured "set point" body temperature. Locusts infected with the deuteromycete fungal pathogen Metarhizium anisopliae var acridumchoose a significantly elevated temperature. This "behavioral fever" greatly delays the progress of mycosis. We have confirmed this phenomenon and shown that desert locusts also fever when infected with the bacterial pathogen Serratia marcescens. Elevation in the prefered environmental temperature occurs also upon injection with laminarin and lipopolysaccharide (microbial cell wall components). Since such treatments also stimulate the immune system it would appear that "behavioral fever" is probably a feature of the immune response. The eicosanoid biosynthesis inhibitor dexamethasone prevented laminarin invoked fever. This effect was reversable by arachidonic acid. Therefore in common with the febrile response in mammals behavioral fever in insects may be mediated locally by circulating eicosanoids.
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Affiliation(s)
- S Bundey
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
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Abstract
AIMS To determine the expediency of a microtitre assay system for establishing, quantifying and antimicrobial testing of two representative oral pathogens. METHODS AND RESULTS Streptococcus mutans and Porphyromonas gingivalis were used. Morphological characteristics of the attached population were evaluated. Biofilm growth was evaluated spectrophotometrically (undisturbed and 1 N NaOH dissipated biofilm). The minimum concentration of chlorhexidine gluconate that inhibited biofilm growth was determined. Growth of the biofilms was successfully monitored by direct optical density measurements or those re-suspended in 1 N NaOH. The latter was necessary when glucans were present in Strep. mutans biofilms. The minimum concentration of chlorhexidine gluconate that inhibited biofilm growth was 1.25 microg ml(-1) for both species. The attached bacteria exhibited common biofilm characteristics. SIGNIFICANCE AND IMPACT OF THE STUDY The assay system developed was especially useful for monitoring the growth of adherent Strep. mutans in the presence of glucans, which is particularly significant for the study of anti-plaque chemicals.
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Affiliation(s)
- S K Roberts
- Department of Periodontics, College of Dentistry, University of Illinois-Chicago, Chicago, IL 60612, USA
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González-Koch A, Czaja AJ, Carpenter HA, Roberts SK, Charlton MR, Porayko MK, Rosen CB, Wiesner RH. Recurrent autoimmune hepatitis after orthotopic liver transplantation. Liver Transpl 2001; 7:302-10. [PMID: 11303289 DOI: 10.1053/jlts.2001.21449] [Citation(s) in RCA: 148] [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: 02/07/2023]
Abstract
To determine the frequency, risk factors, and consequences of recurrent autoimmune hepatitis after liver transplantation, 41 patients with type 1 disease were monitored after surgery in accordance with a surveillance protocol. Tacrolimus or cyclosporine plus prednisone were administered to each patient, and liver biopsy examinations were performed at least annually according to protocol. Corticosteroid therapy was ultimately discontinued in only 2 patients. Recurrent disease was defined as the presence of lymphoplasmacytic infiltrates in liver tissue in the absence of other causes of allograft dysfunction. Autoimmune hepatitis recurred in 7 patients (17%), and the mean time to recurrence was 4.6 +/- 1 years. Recurrence was asymptomatic in 4 of 7 patients and detected only by surveillance liver biopsy assessment in 2 patients. Histological changes were mild, and there was no progression to cirrhosis during 4.9 +/- 0.9 years of observation. Five-year patient (86% v. 82%; P =.9) and graft (86% v. 67%; P =.5) survival rates were not statistically different between patients with and without recurrent disease. HLA-DR3 or HLA-DR4 occurred more commonly in patients with than without recurrence (100% v. 40%; P =.008) and healthy subjects (100% v. 49%; P =.01). Recurrent disease was unrelated to donor HLA status. In conclusion, recurrence after transplantation for type 1 autoimmune hepatitis is common. Its mild manifestations and favorable prognosis may reflect early detection by a surveillance protocol and/or continuous corticosteroid treatment. HLA-DR3- or HLA-DR4-positive recipients are at risk for recurrence regardless of donor HLA status.
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Affiliation(s)
- A González-Koch
- Department of Laboratory Medicine and Pathology, Mayo Clinic and Mayo Foundation, Rochester, MN, USA
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Abstract
OBJECTIVES To describe trends in primary hepatocellular carcinoma (HCC) incidence and mortality in Australia between 1978 and 1997, and to delineate the effects of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection by examining cases of HCC in Australian-born and overseas-born people separately. DESIGN AND SETTING Retrospective analysis of national incidence and mortality data in which the underlying cause was coded as HCC (International classification of diseases, ninth revision [ICD-9] code 155.0). MAIN OUTCOME MEASURES Changes in age-standardised HCC incidence rates in men and women between 1983 and 1996; age-standardised HCC death rates in Australian-born and overseas-born men and women between 1978 and 1997. RESULTS Age-standardised incidence rates increased in men and women (from 2.06 and 0.57 per 100,000 respectively in 1983-1985 to 3.97 and 0.99 respectively in 1995-1996). Age-standardised death rates increased in Australian-born and overseas-born men and overseas-born women (from 1.43, 2.35 and 0.62 respectively per 100,000 in 1978-1982 to 2.50, 4.41 and 1.36 respectively in 1993-1997). However, death rates in Australian-born women did not increase (0.58 per 100,000 in 1978-1982 and 0.63 in 1993-1997). CONCLUSIONS HCC incidence and death rates in Australia have increased over the past two decades, except in Australian-born women. A likely explanation for at least a portion of this increase is increased prevalences of HBV and HCV infection in Australia.
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Affiliation(s)
- M G Law
- National Centre in HIV Epidemiology and Clinical Research, The University of New South Wales, Sydney.
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Abstract
The transport and accumulation of K(+) in higher plant roots is regulated by ABA. Molecular and electrophysiological techniques have identified a number of discrete transporters which are involved in the translocation of K(+) from the soil solution to the shoots of higher plants. Furthermore, recent reports have shown that ABA regulates K(+) channel activity in maize and Arabidopsis roots which suggests that ABA regulation of K(+) transport in roots is, at least in part, ion channel-mediated. The signalling processes which underlie the ABA regulation of K(+) channels have been investigated. The effects of ABA on the membrane potential of intact maize root cells were also studied. It was found that ABA regulated the membrane potential of root cells and that this regulation is consistent with the hypothesis that ABA-induced K(+) accumulation in roots is mediated by K(+) channels.
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Affiliation(s)
- S K Roberts
- The Plant Laboratory, Department of Biology, University of York, PO Box 373, York YO1 5YW, UK.
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Baddour LM, Hicks DV, Tayidi MM, Roberts SK, Walker E, Smith RJ, Sweitzer DS, Herrington JA, Painter BG. Risk factor assessment for the acquisition of fluoroquinolone-resistant isolates of Pseudomonas aeruginosa in a community-based hospital. Microb Drug Resist 2000; 1:219-22. [PMID: 9158778 DOI: 10.1089/mdr.1995.1.219] [Citation(s) in RCA: 18] [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: 02/04/2023] Open
Abstract
A case-control study was performed in a community-based nonteaching hospital to assess patient risk factors for the acquisition of fluoroquinolone-resistant isolates of Pseudomonas aeruginosa. Fifty-five patients who were hospitalized between July 1, 1993 and December 31, 1993 and who had P. aeruginosa recovered from a clinical specimen were included in the analysis. Two patient populations were designated based on the fluoroquinolone susceptibility of their P. aeruginosa isolates. Statistical evaluation using univariate analysis of demographic and clinical data from the 42 patients with quinolone-susceptible P. aeruginosa and the 13 patients with quinolone-resistant P. aeruginosa demonstrated that prior receipt of a fluoroquinolone was the only significant risk factor for the subsequent emergence of fluoroquinolone resistance among P. aeruginosa isolated from patients hospitalized in this small community-based institution (p = 0.0196). Multivariate analysis supported the finding that prior receipt of a fluoroquinolone was the major risk factor for the isolation of fluoroquinolone-resistant P. aeruginosa (p = 0.0004); isolation of this Gram-negative bacillus from sputum (p = 0.0306) and a history of recent surgery (p = 0.0058) were also significantly associated as risk factors for resistance.
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Affiliation(s)
- L M Baddour
- Department of Medicine, University of Tennessee Medical Center at Knoxville 37920-6999, USA
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46
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Abstract
We have used the patch clamp technique to characterize whole-cell currents in spheroplasts isolated from a trk1Delta trk2Delta strain of Saccharomyces cerevisiae which lacks high- and moderate-affinity K+ uptake capacity. In solutions in which extracellular divalent cation concentrations were 0.1 mM, cells exhibited a large inward current. This current was not the result of increasing leak between the glass pipette and membrane, as there was no effect on the outward current. The inward current comprised both instantaneous and time-dependent components. The magnitude of the inward current increased with increasing extracellular K+ and negative membrane potential but was insensitive to extracellular anions. Replacing extracellular K+ with Rb+, Cs+, or Na+ only slightly modulated the magnitude of the inward current, whereas replacement with Li+ reduced the inward current by approximately 50%, and tetraethylammonium (TEA+) and choline were relatively impermeant. The inward current was blocked by extracellular Ca2+ and Mg2+ with apparent Kis (at -140 mV) of 363 +/- 78 and 96 +/- 14 microM, respectively. Furthermore, decreasing cytosolic K+ increased the magnitude of the inward current independently of the electrochemical driving force for K+ influx, consistent with regulation of the inward current by cytosolic K+. Uptake of 86Rb+ by intact trk1Delta trk2Delta cells was inhibited by extracellular Ca2+ with a Ki within the range observed for the inward current. Furthermore, increasing extracellular Ca2+ from 0.1 to 20 mM significantly inhibited the growth of these cells. These results are consistent with those of the patch clamp experiments in suggesting that low-affinity uptake of alkali cations in yeast is mediated by a transport system sensitive to divalent cations.
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Affiliation(s)
- S K Roberts
- Plant Laboratory, Department of Biology, University of York, York YO1 5YW, United
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47
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Abstract
End-stage liver disease secondary to cryptogenic cirrhosis is the indication for orthotopic liver transplantation (OLT) in 7% to 14% of recipients. However, there are no reports documenting the outcome of OLT for this indication. The aim of this study was to determine (1) survival and (2) the incidence of histological recurrence of cryptogenic cirrhosis after OLT. Between March 1985 and December 1994, 560 OLTs were performed at our institution. Of these, 39 transplants for cryptogenic cirrhosis were in patients who met the following criteria: antinuclear antibody < 1:40; negative anti-smooth muscle antibody, antimitochondrial antibody, polymerase chain reaction for hepatitis C virus, and hepatitis B surface antigen results; normal ceruloplasmin and alpha-1 antitrypsin phenotype; transferrin saturation < 65%; and liver biopsy specimen not suggestive of hemochromatosis or other known disorders. Histological recurrence was assessed with protocol liver biopsies in all patients who survived longer than 6 months. The mean age of cryptogenic recipients at the time of transplantation was significantly lower (40.6 years; range, 3 to 63 years) than that of noncryptogenic recipients (48.5 years; range, 1-70; P < .03). Median modified Child's-Pugh score was slightly higher for cryptogenic recipients at the time of transplantation (10.0 + 0.08 standard error of mean [SEM]), than for the noncryptogenic recipients (9.0 + 0.03 SEM; P < .02). Actuarial survival was 72% (+ 0.07 SEM) at 1 and 58% (+ 0.08 SEM) at 5 years for cryptogenic recipients compared with 89% at 1 and 80% at 5 years for noncryptogenic recipients. The difference in survival was significant (P < .001) at both 1 and 5 years. Among the 27 cryptogenic recipients surviving more than 6 months (mean follow-up, 5.5 years), 6 have persistent hepatitis histologically without apparent infectious, vascular, biliary, or drug origins. Four patients (15%) had chronic active hepatitis, and 2 (7%) had steatohepatitis. No cases of recurrent cryptogenic cirrhosis were seen. OLT for cryptogenic cirrhosis is associated with a poor outcome compared with other indications, hepatitis of uncertain origin occurred in 22% of cryptogenic recipients surviving longer than 6 months, and no evidence of recurrence of cryptogenic cirrhosis was seen thus far in follow-up.
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Affiliation(s)
- M R Charlton
- Liver Transplantation Unit, Mayo Clinic, Rochester, MN 55905, USA
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48
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Abstract
Upper gastrointestinal bleeding remains a common medical emergency with high morbidity and mortality. High risk patients are best managed in specialised units. Endoscopy is the procedure of choice for diagnosis and haemostatic therapy of peptic ulcers, reducing deaths and the probability of rebleeding, as well as the need for surgery; for acute variceal bleeding, pharmacotherapy followed by endoscopic ligation is recommended.
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Affiliation(s)
- S K Roberts
- Department of Gastroenterology, The Alfred Healthcare Group, Melbourne, VIC.
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49
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Abstract
The mechanisms mediating Na(+) transpdrt in higher plant roots were investigated by applying the patch clamp technique to protoplasts isolated from the cortex and stele of maize roots. In the cortex, permeation of Na+ through a time-dependent K(+)-selective inward rectifier was negligible. Instead, Na(+) influx into maize roots probably occurs via an instantaneously-activating current. This current was partially inhibited by extracellular Ca(2+), but was insensitive to extracellular TEA(+), Cs(+) and TTX. In outside-out patches, a plasma membrane ion channel was found which mediated an inward Na(+) current which, at least in part, underlies the whole-cell instantaneously-activating current. The unitary conductance of this channel was 15 pS in 102:121 mM Na(+) (outsidexytosol). Channel gating was voltage-independent and distinct from that observed for the inwardly rectifying K(+)-selective channel in the same cell type. Increasing extracellular Ca(2+) from 0.1 to 1 mM reduced the open probability and unitary conductance of this channel. In 102 mM Na(+) : 123 mM K(+) (outside:cytosol) a P(Na):P(K) of 2.1 was calculated. It is suggested that the plasma membrane Na(+)-permeable channel identified in the cortex of maize roots represents a pathway for low affinity Na(+) uptake by intact maize roots. In the stele, permeation of Na(+) through outwardly rectifying K(+) channels was found to be negligible and the channels are thus unlikely to be involved in the transport of Na(+) from the root symplasm.
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Affiliation(s)
- S K Roberts
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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50
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Abstract
Our understanding of the pathobiology of biliary epithelia is rapidly growing because of a surge of investigative activity. This became possible after suitable experimental models and techniques were developed with which to study cholangiocyte biology. Although the molecular mechanisms of bile formation by cholangiocytes and the role of these cells as a major cellular target in a variety of severe hepatobiliary diseases are currently being investigated, many questions remain unanswered, particularly regarding cholangiocellular functions, both in normal and abnormal conditions. As current experimental models become more refined, scientists with interests as diverse as cell biology and physiology, morphology, pharmacology, immunology, genetics, and oncology can be expected to further clarify the pathobiology of biliary epithelia.
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Affiliation(s)
- S K Roberts
- Department of Biochemistry and Molecular Biology, Mayo Medical School, Clinic and Foundation, Rochester, Minnesota, USA
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