1
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Booth S, Kirkwood A, Johnson P, Barrington S, Gallop‐Evans E, Peggs K, Warbey V, Burton C, Ardavan A, Phillips B, Lawrie E, Pike L, Northend M, Clifton‐Hadley L, Jenner R, Collins GP. ANIMATE: A PHASE II STUDY OF NIVOLUMAB IN TRANSPLANT ELIGIBLE PATIENTS WITH RELAPSED/REFRACTORY CLASSIC HODGKIN LYMPHOMA. Hematol Oncol 2021. [DOI: 10.1002/hon.159_2880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- S. Booth
- Oxford University Hospitals Department of Haematology Oxford UK
| | - A. Kirkwood
- UCL Cancer Institute CR UK and UCL Cancer Trials Centre London UK
| | - P. Johnson
- University of Southampton Department of Medicine London UK
| | - S. Barrington
- King’s College London King’s College London and Guys’ & St Thomas PET Imaging Centre London UK
| | - E. Gallop‐Evans
- Velindre University NHS Trust Department of Oncology Cardiff UK
| | - K. Peggs
- University College London Hospitals Haematology London UK
| | - V. Warbey
- King’s College London King’s College London and Guys’ & St Thomas PET Imaging Centre London UK
| | - C. Burton
- Leeds Cancer Centre Haematology Leeds UK
| | - A. Ardavan
- University of Oxford Department of Physics Oxford UK
| | - B. Phillips
- University of Manchester and Manchester Academic Health Science Centre Division of Cancer Science Manchester UK
| | - E. Lawrie
- UCL Cancer Institute CR UK and UCL Cancer Trials Centre London UK
| | - L. Pike
- King’s College London King’s College London and Guys’ & St Thomas PET Imaging Centre London UK
| | - M. Northend
- UCL Cancer Institute CR UK and UCL Cancer Trials Centre London UK
| | | | - R. Jenner
- UCL Cancer Institute CR UK and UCL Cancer Trials Centre London UK
| | - G. P. Collins
- Oxford University Hospitals Department of Haematology Oxford UK
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2
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Hoskin P, Kirkwood A, Popova B, Schofield O, Brammer C, Robinson M, Brunt M, Krishnaswamy M, Illidge T, Gallop-Evans E, Syndikus I, Clifton-Hadley L. LONG TERM FOLLOW-UP OF FoRT: A PHASE 3 MULTI-CENTER PROSPECTIVE RANDOMIZED TRIAL OF RADIATION THERAPY FOR FOLLICULAR AND MARGINAL ZONE LYMPHOMA. Hematol Oncol 2019. [DOI: 10.1002/hon.34_2630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- P. Hoskin
- Cancer Centre; Mount Vernon Cancer Centre and University of Manchester; Northwood United Kingdom
| | - A. Kirkwood
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London United Kingdom
| | - B. Popova
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London United Kingdom
| | - O. Schofield
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London United Kingdom
| | - C. Brammer
- Cancer Centre; Clatterbridge Cancer Centre; Wirral United Kingdom
| | - M. Robinson
- Radiotherapy; Weston Park Hospital; Sheffield United Kingdom
| | - M. Brunt
- Cancer Centre; Royal Stoke University Hospital & Keele University, Stoke-on-Trent; Staffordshire United Kingdom
| | - M. Krishnaswamy
- Oncology; Southend University Hospital; Westcliff-on-Sea United Kingdom
| | - T. Illidge
- Manchester Cancer Research Institute; University of Manchester; Manchester United Kingdom
| | - E. Gallop-Evans
- Velindre Hospital; Velindre Cancer Centre; Cardiff United Kingdom
| | - I. Syndikus
- Cancer Centre; Clatterbridge Cancer Centre; Wirral United Kingdom
| | - L. Clifton-Hadley
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London United Kingdom
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3
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Lim S, Burton C, Barrans S, Kirkwood A, Patrick P, Stevens L, Clifton-Hadley L, Johnson P, Thirdborough S. TRANSCRIPTIONAL NETWORKS ASSOCIATED WITH TREATMENT FAILURE IN ADVANCED-STAGE HODGKIN LYMPHOMA: DATA FROM THE RATHL TRIAL (CRUK/07/033). Hematol Oncol 2019. [DOI: 10.1002/hon.103_2630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- S.H. Lim
- Centre for Cancer Immunology & CRUK Centre; University of Southampton; Southampton United Kingdom
| | - C. Burton
- HMDS; Leeds Cancer Centre; Leeds United Kingdom
| | - S. Barrans
- HMDS; Leeds Cancer Centre; Leeds United Kingdom
| | - A. Kirkwood
- CR UK & UCL Cancer Trials Centre; UCL Cancer Institute, University College London; London United Kingdom
| | - P. Patrick
- CR UK & UCL Cancer Trials Centre; UCL Cancer Institute, University College London; London United Kingdom
| | - L. Stevens
- CR UK & UCL Cancer Trials Centre; UCL Cancer Institute, University College London; London United Kingdom
| | - L. Clifton-Hadley
- CR UK & UCL Cancer Trials Centre; UCL Cancer Institute, University College London; London United Kingdom
| | - P.W. Johnson
- Centre for Cancer Immunology & CRUK Centre; University of Southampton; Southampton United Kingdom
| | - S.M. Thirdborough
- Centre for Cancer Immunology & CRUK Centre; University of Southampton; Southampton United Kingdom
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4
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Trotman J, Fosså A, Federico M, Stevens L, Kirkwood A, Clifton-Hadley L, Patrick P, Berkahn L, D'Amore F, Enblad G, Luminari S, Radford J, Barrington S, Johnson P. RESPONSE-ADJUSTED THERAPY FOR ADVANCED HODGKIN LYMPHOMA (RATHL) TRIAL: LONGER FOLLOW UP CONFIRMS EFFICACY OF DE-ESCALATION AFTER a NEGATIVE INTERIM PET SCAN (CRUK/07/033). Hematol Oncol 2017. [DOI: 10.1002/hon.2437_53] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- J. Trotman
- Haematology, Concord Repatriation General Hospital; University of Sydney; Concord Australia
| | - A. Fosså
- Medical Oncology; Oslo University Hospital; Oslo Norway
| | - M. Federico
- Diagnostic Clinical and Public Health Medicine; University of Modena and Reggio Emilia; Modena Missouri Italy
| | - L. Stevens
- Cancer Trials Centre; Cancer Research UK and University College London; London UK
| | - A. Kirkwood
- Cancer Trials Centre; Cancer Research UK and University College London; London UK
| | - L. Clifton-Hadley
- Cancer Trials Centre; Cancer Research UK and University College London; London UK
| | - P. Patrick
- Cancer Trials Centre; Cancer Research UK and University College London; London UK
| | - L. Berkahn
- Haematology; Auckland City Hospital; Auckland New Zealand
| | - F. D'Amore
- Haematology; Aarhus University Hospital; Aarhus C Denmark
| | - G. Enblad
- Immunology, Genetics and Pathology; Uppsala University; Uppsala Sweden
| | - S. Luminari
- Arcispedale Santa Maria Nuova; Istituti di Ricovero e Cura a Carattere Scientifico; Reggio Emilia Italy
| | - J. Radford
- Medical Oncology; Christie Hospital; Manchester UK
| | - S.F. Barrington
- The PET Imaging Centre, King's College London; King's Health Partners, St. Thomas' Hospital; London UK
| | - P. Johnson
- Cancer Research UK Centre; University of Southampton; Southampton UK
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5
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Russell J, Collins A, Fowler A, Karanth M, Saha C, Shyamsundar V, Docherty S, Kirkwood A, Maw K, Cooke L, Hodson A, Shah N, Sadullah S, Grigoropoulos N, Uttenthal B, Follows G. Advanced Hodgkin lymphoma in the east of England cancer network: A 10-year comparative analysis of outcomes for ABVD and escalated-BEACOPP treated patients aged 16 to 59. Hematol Oncol 2017. [DOI: 10.1002/hon.2439_59] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- J. Russell
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
| | - A. Collins
- Clinical Haematology; Norfolk and Norwich University Hospital; Norwich UK
| | - A. Fowler
- Clinical Haematology; Peterborough City Hospital; Peterborough UK
| | - M. Karanth
- Clinical Haematology; West Suffolk Hospital; Bury Saint Edmunds UK
| | - C. Saha
- Clinical Haematology; Norfolk and Norwich University Hospital; Norwich UK
| | - V. Shyamsundar
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
| | - S. Docherty
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
| | - A. Kirkwood
- Cancer Research UK and UCL Cancer Trials Centre; University College London; London UK
| | - K. Maw
- Clinical Haematology; James Paget University Hospital; Great Yarmouth UK
| | - L. Cooke
- Clinical Haematology; Queen Elizabeth Hospital; King's Lynn UK
| | - A. Hodson
- Clinical Haematology; Ipswich Hospital; Ipswich UK
| | - N. Shah
- Clinical Haematology; Norfolk and Norwich University Hospital; Norwich UK
| | - S. Sadullah
- Clinical Haematology; James Paget University Hospital; Great Yarmouth UK
| | - N. Grigoropoulos
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
| | - B. Uttenthal
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
| | - G. Follows
- Clinical Haematology; Cambridge University Hospitals NHS Foundation Trust; Cambridge UK
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6
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Preston A, Kirkwood A, Federico M, Trotman J, Fossa A, Stevens L, Clifton-Hadley L, Patrick P, Berkahn L, d'Amore F, Enblad G, Luminari S, Radford J, Johnson P. OUTCOMES OF TREATMENT FOR OBESE PATIENTS WITH ADVANCED HODGKIN LYMPHOMA IN THE RATHL TRIAL (CRUK/07/033). Hematol Oncol 2017. [DOI: 10.1002/hon.2438_31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- A. Preston
- Pharmacy; University Hospitals Bristol; Bristol UK
| | - A. Kirkwood
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London UK
| | - M. Federico
- Diagnostic Clinical and Public Health Medicine; University of Modena and Reggio Emilia; Modena Italy
| | - J. Trotman
- Haematology, Concord Repatriation General Hospital; University of Sydney; Concord Australia
| | - A. Fossa
- Medical Oncology; Oslo University Hospital; Oslo Norway
| | - L. Stevens
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London UK
| | - L. Clifton-Hadley
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London UK
| | - P. Patrick
- Cancer Research UK & UCL Cancer Trials Centre; University College London; London UK
| | - L. Berkahn
- Haematology; Auckland City Hospital; Auckland New Zealand
| | - F. d'Amore
- Haematology; Aarhus University Hospital; Aarhus C Denmark
| | - G. Enblad
- Immunology, Genetics and Pathology; Uppsala University; Uppsala Sweden
| | - S. Luminari
- Arcispedale Santa Maria Nuova; Istituti di Ricovero e Cura a Carattere Scientifico; Reggio Emilia Italy
| | - J. Radford
- Medical Oncology; Christie Hospital; Manchester UK
| | - P.W. Johnson
- Cancer Research UK Centre; University of Southampton; Southampton UK
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7
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King J, Palmer DH, Johnson P, Ross P, Hubner RA, Sumpter K, Darby S, Braconi C, Iwuji C, Swinson D, Collins P, Patel K, Nobes J, Muazzam I, Blesing C, Kirkwood A, Nash S, Meyer T. Sorafenib for the Treatment of Advanced Hepatocellular Cancer - a UK Audit. Clin Oncol (R Coll Radiol) 2017; 29:256-262. [PMID: 27964898 DOI: 10.1016/j.clon.2016.11.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 10/28/2016] [Accepted: 11/01/2016] [Indexed: 01/08/2023]
Abstract
AIMS Sorafenib is the current standard treatment for advanced hepatocellular carcinoma. We carried out a national audit of UK patients treated with sorafenib as standard-of-care and those treated with systemic therapy in first-line trials. MATERIALS AND METHODS Sorafenib-treated and trial-treated patients were identified via the Cancer Drugs Fund and local databases. Data were collected retrospectively from medical records according to a standard case report form. The primary outcome measure was overall survival, estimated by the Kaplan-Meier method. RESULTS Data were obtained for 448 sorafenib-treated patients from 15 hospitals. The median age was 68 years (range 17-89) and 75% had performance status ≤ 1. At baseline, 77% were Child-Pugh A and 16.1% Child-Pugh B; 38% were albumin-bilirubin grade 1 (ALBI-1) and 48% ALBI-2; 23% were Barcelona Clinic Liver Classification B (BCLC-B) and 72% BCLC-C. The median time on sorafenib was 3.6 months, with a mean daily dose of 590 mg. The median overall survival for 448 evaluable sorafenib-treated patients was 8.5 months. There were significant differences in overall survival comparing Child-Pugh A versus Child-Pugh B (9.5 versus 4.6 months), ALBI-1 versus ALBI-2 (12.9 versus 5.9 months) and BCLC-B versus BCLC-C (13.0 versus 8.3 months). For trial-treated patients (n=109), the median overall survival was 8.1 months and this was not significantly different from the sorafenib-treated patients. CONCLUSION For Child-Pugh A patients with good performance status, survival outcomes were similar to those reported in global randomised controlled trials. Patients with ALBI grade > 1, Child-Pugh B or poor performance status seem to derive limited benefit from sorafenib treatment.
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Affiliation(s)
- J King
- Department of Oncology, Royal Free London NHS Foundation Trust, London, UK
| | - D H Palmer
- University of Birmingham, Birmingham, UK; University of Liverpool, Liverpool, UK; Clatterbridge Cancer Centre, Wirral, UK
| | - P Johnson
- University of Birmingham, Birmingham, UK; University of Liverpool, Liverpool, UK; Clatterbridge Cancer Centre, Wirral, UK
| | - P Ross
- King's College Hospital, London, UK
| | - R A Hubner
- The Christie NHS Foundation Trust, Manchester, UK
| | - K Sumpter
- The Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, UK
| | - S Darby
- Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - C Braconi
- University of Glasgow, Beatson West of Scotland Cancer Centre, Glasgow, UK
| | - C Iwuji
- Leicester Royal Infirmary, Leicester, UK
| | - D Swinson
- Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - P Collins
- University Hospitals Bristol NHS Foundation Trust, Bristol, UK
| | - K Patel
- Oxford University Hospitals NHS Trust, Oxford, UK
| | - J Nobes
- Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
| | - I Muazzam
- Hull and East Yorkshire Hospitals NHS Trust, Hull, UK
| | - C Blesing
- Great Western Hospital NHS Trust, Swindon, UK
| | - A Kirkwood
- Cancer Research UK & UCL Cancer Trials Centre, London, UK
| | - S Nash
- Cancer Research UK & UCL Cancer Trials Centre, London, UK
| | - T Meyer
- Department of Oncology, Royal Free London NHS Foundation Trust, London, UK; UCL Cancer Institute, London, UK.
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8
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Brown N, Ganguli S, Kirkwood A, Imseeh G, Kristeleit R, Forster M, Meyer T. Clinical outcomes and predicting early death in early phase trials: The NIHR UCLH clinical research facility (CRF) experience. Ann Oncol 2016. [DOI: 10.1093/annonc/mdw368.46] [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: 11/14/2022] Open
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9
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Perna C, Eminowicz G, Asghar U, Imseeh G, Kirkwood A, Mitra A, Arora R, Kristeleit R, McCormack M. Uterine carcinosarcoma: a retrospective clinical cohort analysis. Ann Oncol 2016. [DOI: 10.1093/annonc/mdw374.45] [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: 11/13/2022] Open
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10
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Kularatne B, Arora R, Elshstein G, Guppy N, Kirkwood A, Meyer T, Kristeleit R. Immunohistochemistry (IHC) evaluation of a novel 4-protein prognostic and predictive biomarker panel in endometrial cancer (EC). Ann Oncol 2016. [DOI: 10.1093/annonc/mdw374.36] [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: 11/13/2022] Open
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11
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Gallagher S, Kapur A, Lovell MJ, Jones DA, Kirkwood A, Hassan S, Archbold RA, Wragg A, Uppal R, Yaqoob MM. Impact of diabetes mellitus and renal insufficiency on 5-year mortality following coronary artery bypass graft surgery: a cohort study of 4869 UK patients. Eur J Cardiothorac Surg 2014; 45:1075-81. [DOI: 10.1093/ejcts/ezt630] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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12
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Kirkwood A, Stacey S, Broomhead C. Yes, what about prions? Anaesthesia 2013; 68:1073-4. [DOI: 10.1111/anae.12440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Hoskin P, Kirkwood A, Popova B, Brammer C, Diez P, Robinson M, Syndikus I, Jack A, Smith P. FoRT: A Phase 3 Multi-Center Prospective Randomized Trial of Low Dose Radiation Therapy for Follicular and Marginal Zone Lymphoma. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2012.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Savonenko A, Munoz P, Melnikova T, Wang Q, Liang X, Breyer RM, Montine TJ, Kirkwood A, Andreasson K. Impaired cognition, sensorimotor gating, and hippocampal long-term depression in mice lacking the prostaglandin E2 EP2 receptor. Exp Neurol 2009; 217:63-73. [PMID: 19416671 DOI: 10.1016/j.expneurol.2009.01.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/19/2008] [Accepted: 01/16/2009] [Indexed: 02/08/2023]
Abstract
Cyclooxygenase-2 (COX-2) is a neuronal immediate early gene that is regulated by N-methyl d aspartate (NMDA) receptor activity. COX-2 enzymatic activity catalyzes the first committed step in prostaglandin synthesis. Recent studies demonstrate an emerging role for the downstream PGE(2) EP2 receptor in diverse models of activity-dependent synaptic plasticity and a significant function in models of neurological disease including cerebral ischemia, Familial Alzheimer's disease, and Familial amyotrophic lateral sclerosis. Little is known, however, about the normal function of the EP2 receptor in behavior and cognition. Here we report that deletion of the EP2 receptor leads to significant cognitive deficits in standard tests of fear and social memory. EP2-/- mice also demonstrated impaired prepulse inhibition (PPI) and heightened anxiety, but normal startle reactivity, exploratory behavior, and spatial reference memory. This complex behavioral phenotype of EP2-/- mice was associated with a deficit in long-term depression (LTD) in hippocampus. Our findings suggest that PGE(2) signaling via the EP2 receptors plays an important role in cognitive and emotional behaviors that recapitulate some aspects of human psychopathology related to schizophrenia.
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Affiliation(s)
- A Savonenko
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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15
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Ou ZJ, Ou JS, Ma H, Su CJ, Pritchard KA, Kirkwood A. [A comparison between L-4F and SC-4F in preventing low density lipoprotein induced endothelial cell dysfunction in cell culture]. Zhonghua Xin Xue Guan Bing Za Zhi 2005; 33:411-4. [PMID: 15932696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
OBJECTIVE To investigate the importance of the specific structure of L-4F, an apolipoprotein A-1 mimetic, in inhibiting atherosclerosis. The study was designed to compare the effect of L-4F and scramble-4F (SC-4F) in preventing low density lipoprotein (LDL) induced endothelial cell dysfunction. L-4F and SC-4F has the same amino acids but different nucleotide sequence. METHODS Bovine aortic endothelial cells (BAEC) were incubated with single L-4F 10 microg/ml or SC-4F 10 microg/ml, or LDL 6.2 mmol/L in the absence or presence of L-4F 10 microg/ml or SC-4F 10 microg/ml for 24 h and assayed for (1) changes of superoxide anion (O2-*) generation in BAEC by superoxide dismutase (SOD)-inhibitable ferricytochrome C reduction, and (2) the production of nitric oxide (NO) in BAEC by ozone chemiluminescence with VCL3. RESULTS (1) L-4F and SC-4F themselves had no affect on BAEC O2-* generation. (2) LDL significantly increased O2-* generation in BAEC and LDL-induced O2-* generation was inhibited by pretreatment of LDL with L-4F. However, pretreatment of LDL with SC-4F had no effect on inhibition of LDL-induced O2-* generation. (3) LDL significantly inhibited NO generation in BAEC and pretreatment of LDL with L-4F could inhibit LDL-induced decrease of NO generation, but pretreatment of LDL with SC-4F still inhibited NO generation in BAEC. CONCLUSION L-4F can prevent LDL induced endothelial cell dysfunction by maintaining the balance of NO and O2-*, but SC-4F doesn't. It suggests that the specific structure of L-4F may play a crucial role in preventing atherosclerosis and it may provide a new clue for searching a novel approach on prevention and therapeutics of atherosclerosis in the future.
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Affiliation(s)
- Zhi-jun Ou
- Department of Cardiology, First Affiliated Hospital of Guangzhou Medical College, Guangzhou 510120, China
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16
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Morales B, Rozas C, Pancetti F, Kirkwood A. [Critical period of cortical plasticity]. Rev Neurol 2003; 37:739-43. [PMID: 14593633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
INTRODUCTION AND DEVELOPMENT Alterations of sensory experience cause large-scale re-arrangements of cortical connectivity only early in life. After a critical period that roughly ends by puberty, comparable modifications requires more invasive manipulations, including deafferentation and cortical lesions. At a cellular level, the elementary mechanisms responsible for synaptic modification appear to be available throughout life. Thus, in adults, experience dependent plasticity might be constrained additional factors, like the maturation of inhibition or changes in the extra cellular matrix. Such view is consistent with a limited, but not absent, modifiability of adult cortical circuits. This view also has interesting therapeutical implications. CONCLUSION In this scenario, manipulation of these limiting factors, for example reducing synaptic inhibition, might be a useful strategy to enhance plasticity and to restore function in the adult cortex.
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Affiliation(s)
- B Morales
- Faculdad de Química y Biología, Universidad de Santiago de Chile, Santiago de Chile, Chile
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17
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Yu H, Saura CA, Choi SY, Sun LD, Yang X, Handler M, Kawarabayashi T, Younkin L, Fedeles B, Wilson MA, Younkin S, Kandel ER, Kirkwood A, Shen J. APP processing and synaptic plasticity in presenilin-1 conditional knockout mice. Neuron 2001; 31:713-26. [PMID: 11567612 DOI: 10.1016/s0896-6273(01)00417-2] [Citation(s) in RCA: 197] [Impact Index Per Article: 8.6] [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: 12/25/2022]
Abstract
We have developed a presenilin-1 (PS1) conditional knockout mouse (cKO), in which PS1 inactivation is restricted to the postnatal forebrain. The PS1 cKO mouse is viable and exhibits no gross abnormalities. The carboxy-terminal fragments of the amyloid precursor protein differentially accumulate in the cerebral cortex of cKO mice, while generation of beta-amyloid peptides is reduced. Expression of Notch downstream effector genes, Hes1, Hes5, and Dll1, is unaffected in the cKO cortex. Although basal synaptic transmission, long-term potentiation, and long-term depression at hippocampal area CA1 synapses are normal, the PS1 cKO mice exhibit subtle but significant deficits in long-term spatial memory. These results demonstrate that inactivation of PS1 function in the adult cerebral cortex leads to reduced Abeta generation and subtle cognitive deficits without affecting expression of Notch downstream genes.
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Affiliation(s)
- H Yu
- Center for Neurologic Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA
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18
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Rozas C, Frank H, Heynen AJ, Morales B, Bear MF, Kirkwood A. Developmental inhibitory gate controls the relay of activity to the superficial layers of the visual cortex. J Neurosci 2001; 21:6791-801. [PMID: 11517267 PMCID: PMC6763109] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
A developmental reduction in the radial transmission of synaptic activity has been proposed to underlie the end of the critical period for experience-dependent modification in layers II/III of the visual cortex. Using paired-pulse stimulation, we investigated in visual cortical slices how the propagation of synaptic activity to the superficial layers changes during development and how this process is affected by sensory experience. The results can be summarized as follows. (1) Layers II/III responses to repetitive stimulation of the white matter become increasingly depressed between the third and sixth week of postnatal development, a time course that parallels the end of the critical period. (2) Paired-pulse depression is reduced after dark rearing and also by blocking inhibitory synaptic transmission. (3) Paired-pulse depression and its regulation by age and sensory experience is more pronounced when stimulation is applied to the white matter than when applied to layer IV. Together, these results are consistent with the idea that the maturation of intracortical inhibition reduces the capability of the cortex to relay incoming high-frequency patterns of activity to the supragranular layers.
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Affiliation(s)
- C Rozas
- Department of Neuroscience, Howard Hughes Medical Institute, Brown University, Providence, Rhode Island 02912, USA
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19
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Abstract
Cortical plasticity seems to be critical for the establishment of permanent memory traces. Little is known, however, about the molecular and cellular processes that support consolidation of memories in cortical networks. Here we show that mice heterozygous for a null mutation of alpha-calcium-calmodulin kinase II (alpha-CaMKII+/-) show normal learning and memory 1-3 days after training in two hippocampus-dependent tasks. However, their memory is severely impaired at longer retention delays (10-50 days). Consistent with this, we found that alpha-CaMKII+/- mice have impaired cortical, but not hippocampal, long-term potentiation. Our results represent a first step in unveiling the molecular and cellular mechanisms underlying the establishment of permanent memories, and they indicate that alpha-CaMKII may modulate the synaptic events required for the consolidation of memory traces in cortical networks.
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Affiliation(s)
- P W Frankland
- Departments of Neurobiology, Psychiatry and Psychology, Brain Research Institute, University of California, Los Angeles, California 90095-1761, USA
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20
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Affiliation(s)
- A Kirkwood
- Mind Brain Institute, Department of Neurosciences, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
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21
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Huang ZJ, Kirkwood A, Pizzorusso T, Porciatti V, Morales B, Bear MF, Maffei L, Tonegawa S. BDNF regulates the maturation of inhibition and the critical period of plasticity in mouse visual cortex. Cell 1999; 98:739-55. [PMID: 10499792 DOI: 10.1016/s0092-8674(00)81509-3] [Citation(s) in RCA: 893] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Maturation of the visual cortex is influenced by visual experience during an early postnatal period. The factors that regulate such a critical period remain unclear. We examined the maturation and plasticity of the visual cortex in transgenic mice in which the postnatal rise of brain-derived neurotrophic factor (BDNF) was accelerated. In these mice, the maturation of GABAergic innervation and inhibition was accelerated. Furthermore, the age-dependent decline of cortical long-term potentiation induced by white matter stimulation, a form of synaptic plasticity sensitive to cortical inhibition, occurred earlier. Finally, transgenic mice showed a precocious development of visual acuity and an earlier termination of the critical period for ocular dominance plasticity. We propose that BDNF promotes the maturation of cortical inhibition during early postnatal life, thereby regulating the critical period for visual cortical plasticity.
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Affiliation(s)
- Z J Huang
- Center for Learning and Memory, Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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22
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Kirkwood A, Rozas C, Kirkwood J, Perez F, Bear MF. Modulation of long-term synaptic depression in visual cortex by acetylcholine and norepinephrine. J Neurosci 1999; 19:1599-609. [PMID: 10024347 PMCID: PMC6782177] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
In a slice preparation of rat visual cortex, we discovered that paired-pulse stimulation (PPS) elicits a form of homosynaptic long-term depression (LTD) in the superficial layers when carbachol (CCh) or norepinephrine (NE) is applied concurrently. PPS by itself, or CCh and NE in the absence of synaptic stimulation, produced no lasting change. The LTD induced by PPS in the presence of NE or CCh is of comparable magnitude with that obtained with prolonged low-frequency stimulation (LFS) but requires far fewer stimulation pulses (40 vs 900). The cholinergic facilitation of LTD was blocked by atropine and pirenzepine, suggesting involvement of M1 receptors. The noradrenergic facilitation of LTD was blocked by urapidil and was mimicked by methoxamine, suggesting involvement of alpha1 receptors. beta receptor agonists and antagonists were without effect. Induction of LTD by PPS was inhibited by NMDA receptor blockers (completely in the case of NE; partially in the case of CCh), suggesting that one action of the modulators is to control the gain of NMDA receptor-dependent homosynaptic LTD in visual cortex. We propose that this is a mechanism by which cholinergic and noradrenergic inputs to the neocortex modulate naturally occurring receptive field plasticity.
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Affiliation(s)
- A Kirkwood
- Mind Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218, USA
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23
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Kirkwood A. Safe water for Africa. Afr Health 1998; 20:9-11. [PMID: 12321818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
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24
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Abstract
Synaptic long-term potentiation (LTP) and long-term depression (LTD) were studied in the visual cortex of mutant mice lacking alpha-calcium/calmodulin-dependent protein kinase II (alphaCaMKII). In adult mutants, little LTD or LTP could be elicited using standard conditioning protocols. However, substantial LTD and LTP were induced in 4- to 5-week-old mutants. Thus, the reduction in cortical plasticity in alphaCaMKII (-/-) mice is conditional, with the relevant condition being postnatal age.
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Affiliation(s)
- A Kirkwood
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
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25
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Aizenman CD, Kirkwood A, Bear MF. A current source density analysis of evoked responses in slices of adult rat visual cortex: implications for the regulation of long-term potentiation. Cereb Cortex 1996; 6:751-8. [PMID: 8922331 DOI: 10.1093/cercor/6.6.751] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In slices of visual cortex, long-term potentiation (LTP) of synaptic responses in layer III can be evoked by high-frequency stimulation of a site in the middle of the cortical thickness, corresponding mainly to layer IV. In contrast, stimulation of the white matter-layer VI border typically fails to evoke LTP in adult visual cortex unless GABAA receptors are partially blocked. We performed current-source density (CSD) analysis to determine how the patterns of cortical activation compare under these different stimulation conditions. Single-pulse stimulation of the middle layers (corresponding to layer IV and superficial V) and the deep layers (corresponding to white matter and deep layer VI) yielded very similar CSD patterns. The major current sinks were located within 500 mu m of the pia, corresponding to layers II and III, regardless of the stimulation site. The amplitude of all current sinks was diminished, and the latency was increased, in the presence of high concentrations of divalent cations (12 mM Ca2+ and 12 mM mg2+). Nonetheless, the major synaptic current sink was still present at a depth of approximately 400 microns regardless of the site of stimulation, indicating that stimulation of either site leads to monosynaptic EPSCs in layer III. However, superficial sinks, at a depth of approximately 200 microns, were virtually eliminated by high concentrations of divalent cations after deep layer stimulation, but not after middle layer stimulation, suggesting that stimulation at the two sites recruits different monosynaptic circuits. This conclusion was supported by experiments using paired-pulse stimulation of the two sites (12.5 ms interstimulus interval). While there was little evidence of a paired-pulse interaction after stimulation of the middle layers, there was marked paired-pulse suppression of superficial layer III current sinks after stimulation of the deep layers. Taken together, the data suggest a model in which deep layer stimulation activates the dendrites of layer III cells by a monosynaptic route and by a disynaptic route. The disynaptic input originates in the middle cortical layers and is controlled by inhibition. Differences in synaptic plasticity evoked from the different sites could be explained if the recruitment of middle layer inputs were required for the generation of LTP in layer III.
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Affiliation(s)
- C D Aizenman
- Department of Neuroscience, Howard Hughes Medical Institute, Brown University, Providence, RI 02912, USA
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26
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27
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Abstract
In many regions of the cerebral cortex, Ca2+ influx through NMDA (N-methyl-D-aspartate) sensitive glutamate receptors (NMDA receptors) can trigger two forms of synaptic plasticity: long-term depression (LTD) and long-term potentiation (LTP). LTD is induced by low levels of postsynaptic NMDA-receptor activation, for instance in response to low-frequency stimulation, whereas LTP is induced by the stronger activation that occurs following high-frequency stimulation. Theoretical studies have shown that the properties of synaptic LTD and LTP can account for many aspects of experience-dependent plasticity in the developing visual cortex, provided that the LTD-LTP crossover point (the modification threshold, theta(m)) varies as a function of the history of cortical activity. Here we provide direct experimental evidence that the value of theta(m) depends on sensory experience. We find in visual cortex of light-deprived rats that LTP is enhanced and LTD diminished over a range of stimulation frequencies, and that these effects can be reversed by as little as two days of light exposure. Our findings support the idea that a variable synaptic modification threshold allows synaptic weights in neural networks to achieve a stable equilibrium.
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Affiliation(s)
- A Kirkwood
- Department of Neuroscience and Howard Hughes Medical Institute, Brown University, Providence, Rhode Island 02912, USA
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Kirkwood A, Lee HK, Bear MF. Co-regulation of long-term potentiation and experience-dependent synaptic plasticity in visual cortex by age and experience. Nature 1995; 375:328-31. [PMID: 7753198 DOI: 10.1038/375328a0] [Citation(s) in RCA: 356] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Long-term potentiation (LTP) is a lasting enhancement of excitatory synaptic transmission that follows specific patterns of electrical stimulation. Although the mechanism of LTP has been intensively studied, particularly in the hippocampus, its significance for normal brain function remains unproven. It has been proposed that LTP-like mechanisms may contribute to naturally occurring, experience-dependent synaptic modifications in the visual cortex. The formation of normal binocular connections within the visual cortex requires simultaneous input from both eyes during a postnatal critical period that can be delayed by rearing animals in complete darkness. To explore the role of LTP in this experience-dependent maturation process, we induced LTP in visual cortical slices taken at different ages from light-reared and dark-reared rats. Susceptibility to LTP coincides with the critical period and, like the critical period, can be prolonged by rearing animals in darkness. These findings support the hypothesis that LTP reflects a normal mechanism of experience-dependent synaptic modification in the developing mammalian brain.
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Affiliation(s)
- A Kirkwood
- Howard Hughes Medical Institute, Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA
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29
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Kirkwood A. Right to nurse. Culture transplant. Nurs Stand 1994; 9:17-8. [PMID: 7833234 DOI: 10.7748/ns.9.10.17.s32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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30
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Kirkwood A, Bear MF. Homosynaptic long-term depression in the visual cortex. J Neurosci 1994; 14:3404-12. [PMID: 8182481 PMCID: PMC6577491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have investigated the characteristics and mechanism of activity-dependent decreases in synaptic effectiveness in visual cortex. Repetitive, low-frequency stimulation (LFS) of either layer IV or the white matter of visual cortical slices was shown to result in a long-term depression (LTD) of intra- and extracellularly recorded synaptic responses in layer III. In preparations in which responses to stimulation of two independent pathways could be monitored, LFS of one pathway produced LTD of responses to test stimulation of that input only, showing that this form of LTD is homosynaptic. This form of LTD was dependent on the frequency and/or pattern of conditioning stimulation and on activation of NMDA receptors. Okadaic acid, an inhibitor of protein phosphatases 1 and 2a, inhibited LTD, but had no effect on induction of long-term potentiation. In all of these respects, LFS-induced LTD in visual cortex closely resembles what has been recently documented in hippocampus. The combined data support a model in which LTD is triggered by a modest elevation in postsynaptic Ca2+ and activation of protein-serine, threonine phosphatases.
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Affiliation(s)
- A Kirkwood
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
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31
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Abstract
The responses to single photon absorptions (quantum bumps) vary randomly in size in Limulus photoreceptors. This variability is a natural consequence of simple chemical reactions involving a small number of molecules. The measured size distributions differ significantly from the exponential distribution predicted by the simplest transduction cascade models, one feature of which is that light-activated rhodopsin (R*) is turned off in a single step process. As shown in the companion paper, the nonexponential size distributions can be accounted for if R* is turned off in a multi-step process. This would lead to a nonexponential (peaked) distribution in the number of G-protein molecules activated during a quantum bump and to a nonexponential distribution in the size of bumps. To test this possibility we measured the distribution of quantum bump size under two conditions in which the variability in the number of activated G-proteins was eliminated. eliminated. In one method, bumps were produced by direct activation of single G-proteins using GTP-gamma-S; in the second GDP-beta-S reduced the R* gain to the point where most quantal events were due to activation of a single G-protein. In both cases the size distribution of bumps became much closer to an exponential distribution than that of normal light-induced bumps. These results support the idea that the size distribution of light-induced bumps is dependent on events at the R* level and reflects to the multi-step deactivation of R*.
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Affiliation(s)
- A Kirkwood
- Department of Biology, Brandeis University, Waltham, Massachusetts 02254
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32
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Kirkwood A, Bear MF. Hebbian synapses in visual cortex. J Neurosci 1994; 14:1634-45. [PMID: 8126560 PMCID: PMC6577523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We discovered in slices of rat visual cortex that reliable long-term potentiation (LTP) of synaptic responses in layer III could be elicited by theta burst stimulation delivered to a site in the middle of the cortical thickness, corresponding mainly to layer IV. This synaptic plasticity was reflected in the extracellular field potentials and intracellular EPSPs in layer III, but was not observed in the intracellular responses of layer V neurons, suggesting a preferential involvement of synapses on layer III neurons. Tetanus-induced LTP in this preparation was input specific, and was blocked by application of an NMDA receptor antagonist (but not by an antagonist of nitric oxide synthase). In addition, LTP of layer IV-evoked responses could also be produced reliably by pairing low-frequency synaptic stimulation (approximately 100 pulses at 1 Hz) with strong intracellular depolarization of layer III neurons. Thus, LTP in this circuit satisfies the definition of a "Hebbian" modification. Tetanic stimulation of the white matter, in sharp contrast, consistently failed to elicit LTP in layer III unless a GABAA receptor antagonist was applied to the slice. Analysis indicated that the critical difference between layer IV and white matter stimulation was not the magnitude of the responses to single stimuli delivered to the two sites, but that it might lie in the postsynaptic response during high-frequency stimulation. Consistent with this idea, "associative" LTP could be elicited from white matter when converging but independent inputs from the white matter and layer IV simultaneously received tetanic conditioning stimulation. A hypothetical model is presented to account for the differences between layer IV and white matter stimulation. According to this "plasticity gate hypothesis," inhibitory circuitry in layer IV normally acts as a sort of band-pass filter that constrains the types of activity patterns that can gain access to the modifiable synapses in layer III. By stimulating in layer IV, we have bypassed this filter and therefore do not need to block GABAA receptors to achieve the threshold for LTP in layer III.
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Affiliation(s)
- A Kirkwood
- Brown University Department of Neuroscience, Providence, Rhode Island 02912
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33
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Arfeen S, Goodship TH, Kirkwood A, Channon S, Ward MK. 1% amino acid peritoneal dialysate: single-cycle study in diabetic patients with end-stage renal disease. Am J Kidney Dis 1994; 23:86-90. [PMID: 8285202 DOI: 10.1016/s0272-6386(12)80816-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Uremia is associated with multiple abnormalities of carbohydrate and protein metabolism, which are partially corrected by continuous ambulatory peritoneal dialysis with dextrose-based solutions. The hormonal and metabolic effects of amino acid (AA)-based peritoneal dialysis have been studied in nondiabetic uremic patients. Such solutions may be particularly suitable for diabetic patients with end-stage renal disease provided the safety and efficacy of such solutions can be established. We have studied and compared the metabolic and hormonal responses to a single-cycle exchange of dextrose versus a 1% AA-based continuous ambulatory peritoneal dialysis solution in six diabetic patients with end-stage renal disease. In the fasting state and under similar free insulin concentrations, use of the AA solution led to a higher mean glucose concentration (109 +/- 16 mg/dL with dextrose solution v 128 +/- 25 mg/dL with AA solution, P < 0.05). Levels of alanine, lactate, pyruvate, glycerol, non-esterified fatty acids, and triglycerides were similar with the use of either solution. Use of the AA-based solution led to increases in the mean values of the branched chain AAs for the period of the study (valine 131 +/- 10 mumol/L with dextrose solution v 331 +/- 40 mumol/L with AA solution, P < 0.01; leucine 72 +/- 7 mumol/L with dextrose solution v 129 +/- 11 mumol/L with AA solution, P < 0.01; isoleucine 48 +/- 5 mumol/L with dextrose solution v 103 +/- 11 mumol/L with AA solution, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Arfeen
- Department of Internal Medicine, University of Missouri Health Sciences Center, Columbia 65212
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34
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Abstract
Activity-dependent synaptic plasticity in the superficial layers of juvenile cat and adult rat visual neocortex was compared with that in adult rat hippocampal field CA1. Stimulation of neocortical layer IV reliably induced synaptic long-term potentiation (LTP) and long-term depression (LTD) in layer III with precisely the same types of stimulation protocols that were effective in CA1. Neocortical LTP and LTD were specific to the conditioned pathway and, as in the hippocampus, were dependent on activation of N-methyl-D-aspartate receptors. These results provide strong support for the view that common principles may govern experience-dependent synaptic plasticity in CA1 and throughout the superficial layers of the mammalian neocortex.
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Affiliation(s)
- A Kirkwood
- Department of Neuroscience, Brown University, Providence, RI 02912
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35
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Abstract
LTP is a form of activity-dependent synaptic plasticity that has been investigated mainly in the hippocampus. It is considered likely that similar mechanisms may also account for aspects of naturally occurring plasticity in the neocortex. Consequently, an increasing number of studies have been devoted to the investigation of neocortical LTP. Recent results suggest that at least two forms of LTP coexist in layer III of the neocortex. One depends on NMDA-receptor activation and resembles the LTP observed in hippocampal field CA1. A second form is independent of NMDA receptors and requires activation of voltage-sensitive Ca2+ channels.
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Affiliation(s)
- M F Bear
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
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36
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Abstract
M-current is a voltage-gated K+ current that can be turned off by the muscarinic action of acetylcholine. We examined the effects of postsynaptic action potential firing on the level of M-current in B-cells of the bullfrog sympathetic ganglion. High frequency stimulation of action potentials induced an approximately two-fold increase in the level of the M-current that could last up to 35 min. The 'enhanced' M-current was similar to the 'resting' one in its time-dependence, voltage-dependence and sensitivity to neurotransmitters. Experiments were undertaken to examine the functional consequences of the enhanced M-current. Following high frequency stimulation the number of spikes evoked by depolarizing current was reduced. In addition, the excitatory postsynaptic potential (EPSP) evoked by maximal input became subthreshold, thereby blocking information flow through the ganglion cell. These results indicate that the enhancement of M-current by spikes provides a negative feedback mechanism for the control of excitability. It has been reported that postsynaptic stimulation of ganglion cells also produces a long-term increase in the nicotinic EPSP, but we were unable to confirm this observation.
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Affiliation(s)
- A Kirkwood
- Department of Biology, Brandeis University, Waltham, MA 02154
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Lisman J, Erickson MA, Richard EA, Cote RH, Bacigalupo J, Johnson E, Kirkwood A. Mechanisms of amplification, deactivation, and noise reduction in invertebrate photoreceptors. Soc Gen Physiol Ser 1992; 47:175-99. [PMID: 1369761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
In this review we have discussed the problem of deactivation at both the rhodopsin and G protein levels. Of particular interest is the novel observation that rhodopsin deactivation can be modulated by light. This modulation is likely to play an important role in light adaptation by reducing the gain of transduction. One interesting possibility is that this modulation involves the phosphorylation of an arrestin-like molecule, but this remains to be tested. One of the experimental advantages of Limulus photoreceptors is the large size of the single photon responses and the fact that even single G proteins produce a detectable response. This made possible the observation that nonhydrolyzable GTP analogues produce discrete transient events rather than the step-like events that would be predicted by previous models. This observation led us to a new view of how enzyme deactivation is coupled to GTP hydrolysis on G protein. According to this view, enzymes are activated by G protein, but can be deactivated by processes that are not dependent on G protein or the hydrolysis of GTP. We have conducted several types of experiments, including some on the vertebrate rod system, that strongly support this hypothesis. A second major theme of this review is transduction noise. The available biochemical evidence suggests that both G protein and G protein-activated enzymes are likely to become spontaneously active and generate undesirable noise. Our measurements indicate, however, that this noise is orders of magnitude smaller than would be predicted by simple models, suggesting that special mechanisms must exist for suppressing this noise. We have proposed a specific mechanism by which enzymes regulated allosterically by multiple subunits could act as coincidence detectors to reduce transduction noise. Finally, there is the fundamental question of which second messengers have a direct role in invertebrate phototransduction. After Fesenko et al. (1985) showed that the light-dependent conductance in vertebrate rods was modulated by cGMP and not by Ca2+, there was rapid progress in understanding the vertebrate photoreceptor transduction mechanism. Now that it has been established that invertebrate light-dependent channels are regulated by cGMP and not by Ca2+, we can expect rapid progress in understanding invertebrate phototransduction. A key question that needs to be answered is whether the InsP3-Ca2+ pathway somehow triggers changes in cGMP or whether there is an altogether different pathway by which cGMP metabolizing enzymes are affected by light.
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Affiliation(s)
- J Lisman
- Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA
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Abstract
The role of intracellular Ca2+ in the muscarinic suppression of M-current was examined. Intracellular injection of Ca2+ buffer into cells in the intact ganglion reduced the response to muscarinic agonist. In similar experiments on isolated cells, Ca2+ buffer was introduced into the cytoplasm using a perfused recording pipette. Ca2+ buffer (20 mM) with the free Ca2+ concentration set to normal resting levels produced a reversible reduction of the muscarinic response. In a second line of investigation, it was found that pharmacological procedures designed to deplete internal stores of Ca2+ produced a decrease in the muscarinic response. These results, taken together with previous work, support the hypothesis that the muscarinic suppression of M-current is mediated by the release of Ca2+ from intracellular stores.
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Affiliation(s)
- A Kirkwood
- Department of Biology, Brandeis University, Waltham, Massachusetts 02254
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Arfeen S, Goodship TH, Kirkwood A, Ward MK. The nutritional/metabolic and hormonal effects of 8 weeks of continuous ambulatory peritoneal dialysis with a 1% amino acid solution. Clin Nephrol 1990; 33:192-99. [PMID: 2190721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Circulating intermediary metabolites, hormones and plasma amino acids (AA) were measured at intervals over 24 hours in seven non-diabetic patients with chronic renal failure treated by continuous ambulatory peritoneal dialysis (CAPD), before and after an 8-week period during which a 1% amino acid dialysis solution replaced two of the four dextrose exchanges. Mean 24-hour concentrations of plasma total and essential amino acid were higher following the AA dialysate (total pre: 2893 +/- 185; total post: 3357 +/- 244; p less than 0.05; essential pre: 751 +/- 47; essential post: 1064 +/- 57 mumol/l; p less than 0.001). Mean 24-hour concentrations of the branched chain amino acids leucine, isoleucine and valine were higher following the AA dialysate (valine pre: 201 +/- 18; valine post: 321 +/- 19; p less than 0.001; leucine pre: 102 +/- 6; leucine post: 127 +/- 9; p less than 0.01; isoleucine pre: 67 +/- 5; isoleucine post: 85 +/- 7 mumol/l; p less than 0.05). Serum albumin increased with use of the AA dialysate (pre: 36 +/- 1; 2 weeks, 40 +/- 1; 4 weeks, 40 +/- 1; 6 weeks, 41 +/- 1; 8 weeks, 38 +/- 2 g/l). 24-hour profiles and mean 24-hour concentrations of blood glucose, serum insulin, serum triglyceride, plasma non-esterified fatty acids (NEFA), plasma 3-hydroxybutyrate and plasma alanine were unchanged after the AA period. Plasma bicarbonate decreased with use of the amino acid solution (pre: 21 +/- 1; 2 weeks, 18 +/- 1; 4 weeks, 18 +/- 1; 6 weeks, 16 +/- 1; 8 weeks, 16 +/- 1 mmol/l). Use of a 1% amino acid solution over an 8-week period in CAPD patients improves the plasma amino acid profile but results in a metabolic acidosis. The other endocrine and metabolic abnormalities of uremia remain unchanged.
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Affiliation(s)
- S Arfeen
- Department of Medicine, University of Newcastle upon Tyne, UK
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Kirkwood A, Weiner D, Lisman JE. An estimate of the number of G regulator proteins activated per excited rhodopsin in living Limulus ventral photoreceptors. Proc Natl Acad Sci U S A 1989; 86:3872-6. [PMID: 2498877 PMCID: PMC287243 DOI: 10.1073/pnas.86.10.3872] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous work by others on Limulus photoreceptors has shown that application of a variety of guanine nucleotide-binding regulatory protein (G protein) activators produces discrete waves of depolarization similar to those generated by single photos, but smaller in size. We investigated whether these events might originate at a site other than the G protein. Initiation of the events did not depend on the state of the visual pigment, suggesting that the events do not originate at the pigment level. The events could be blocked by the G-protein blocker guanosine 5'-[beta-thio]diphosphate (GDP[betaS]) and thus support the conclusion that these discrete events are due to the activation of G protein itself. Quantitative measurements indicate that the average size of these events is approximately 8 times smaller than that evoked by single photons under the same conditions. Given certain reasonable assumptions, these results imply that the gain of the first stage of transduction in vivo is approximately 8, a value considerably lower than that measured in vitro in vertebrate rods (gain, 100-500). Furthermore, independent evidence for a low first-stage gain in Limulus is derived from the observation that GDP[betaS] barely affects the size of the response to single photons, but greatly reduces the probability that a photon evokes a response. These results can be explained if rhodopsin normally activates only a few G proteins.
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Affiliation(s)
- A Kirkwood
- Department of Biology, Brandeis University, Waltham, MA 02254
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Kirkwood A. Reassuring noises just won't do. Nurs Stand 1988; 2:14. [PMID: 3138548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Kirkwood A. Health politics. Social deprivation must be attacked first. Health Serv J 1986; 96:1577. [PMID: 10279737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
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Golowasch J, Kirkwood A, Miller C. Allosteric effects of Mg2+ on the gating of Ca2+-activated K+ channels from mammalian skeletal muscle. J Exp Biol 1986; 124:5-13. [PMID: 2428908 DOI: 10.1242/jeb.124.1.5] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ca2+-activated K+ channels from rat muscle transverse tubule membranes were inserted into planar phospholipid bilayers, and the activation of these channels by Ca2+ was studied. On the cytoplasmic side of the channel, calcium ions (in the range 10–100 mumol l-1) increase the opening probability of the channel in a graded way. This ‘activation curve’ is sigmoid, with an average Hill coefficient of about 2. Magnesium ions, in the range 1–10 mmol l-1, increase the apparent affinity of the channel for Ca2+ and greatly enhance the sigmoidicity of the Ca2+ activation curve. In the presence of 10 mmol l-1 Mg2+, the Hill coefficient for Ca2+ activation is about 4.5. This effect depends upon Mg2+ concentration but not upon applied voltage. Mg2+ is effective only when added to the cytoplasmic side of the channel. The results argue that this high-conductance, Ca2+-activated K+ channel contains at least six Ca2+-binding sites involved in the activation process.
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Kirkwood A. Sheep scab control with sheep showers. Vet Rec 1978; 103:343-4. [PMID: 569388 DOI: 10.1136/vr.103.15.343-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Kirkwood A. Case of Tumour in the Anterior Lobe of the Brain. MONTHLY JOURNAL OF MEDICAL SCIENCE 1851. [PMCID: PMC5872434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- A. Kirkwood
- Surgeon to the Berwick Dispensary, and to the Infirmary of the Berwick Union
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