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Johnson M, Morrison FJ, McMahon G, Su M, Turchin A. Outcomes in patients with cardiometabolic disease who develop hyperkalemia while treated with a renin-angiotensin-aldosterone system inhibitor. Am Heart J 2023; 258:49-59. [PMID: 36642227 DOI: 10.1016/j.ahj.2023.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [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] [Received: 09/24/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 05/11/2023]
Abstract
BACKGROUND Many patients with indications for renin-angiotensin-aldosterone system inhibitor (RAASi) therapy are not receiving these medications. Concern about hyperkalemia is thought to contribute to this lack of evidence-based therapy. METHODS A retrospective cohort study included adult patients in primary care practices affiliated with an integrated health care delivery system treated with RAASi between 2000 and 2019 for any of the following indications: (a) coronary artery disease (CAD); (b) heart failure (HF) with a left ventricle ejection fraction ≤ 40%; (c) diabetes mellitus (DM) with proteinuria; or (d) chronic kidney disease (CKD) with proteinuria. Relationship between hyperkalemia (K > 5.0 mEg/L) over the first 12 months of follow-up and a composite end point of cardiovascular events, renal dysfunction, and all-cause mortality was evaluated. RESULTS Among 82,732 study patients, 7,727 (9.34%) developed hyperkalemia. Patients with hyperkalemia were older (69.0 vs 64.6) and more likely to have CAD (57.8 vs 53.7%), CKD (57.3 vs 51.1%), HF (19.3 vs 9.7%), and DM (45.3 vs 33.3%) (P < .001 for all). Five-year cumulative risk of the primary outcome was higher in patients who did (63.9%; 95% CI: 62.8%-65.1%) versus did not (37.2%; 95% CI: 36.8%-37.6%) develop hyperkalemia. Five-year cumulative risk of ED visit or hospitalization for hyperkalemia was 15.6% (14.7%-16.6%) for patients with versus 2.7% (95% CI: 2.6-2.9) for patients without hyperkalemia, rising to 25.9% (95% CI: 22.4-29.9) for patients with severe (K > 6.0 mEq/dL) hyperkalemia. Patients who experienced hyperkalemia were more likely (34.4%) than patients who did not (29.2%) to deintensify RAASi therapy (P < .001). Five-year cumulative risk of the primary outcome was higher in patients who lowered RAASi dose (50.4%; 95% CI: 48.5%-52.4%) or stopped RAASi therapy completely (49.3%; 95% CI: 48.5%-50.1%), compared to patients who continued RAASi therapy (36.1%; 95% CI: 25.7-36.5). Similar findings were observed in multivariable analyses and for individual components of the primary outcome. CONCLUSIONS Hyperkalemia is a common complication of RAASi therapy and is associated with an increased risk of multiple adverse outcomes. Patients who have their RAASi medications deintensified after a hyperkalemic event have higher incidence of cardiovascular events, renal dysfunction and death.
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Affiliation(s)
- Matthew Johnson
- Division of Endocrinology, Brigham and Women's Hospital, Boston, MA; Columbia University College of Physicians and Surgeons, New York, NY
| | | | - Gearoid McMahon
- Division of Endocrinology, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA
| | - Maxwell Su
- Harvard School of Public Health, Boston, MA; Phase V, Wellesley Hills, MA
| | - Alexander Turchin
- Division of Endocrinology, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA.
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Macdougall IC, Meadowcroft AM, Blackorby A, Cizman B, Cobitz AR, Godoy S, Jha V, Johansen KL, McMahon G, Obrador GT, Wong MG, Singh AK. Regional Variation of Erythropoiesis-Stimulating Agent Hyporesponsiveness in the Global Daprodustat Dialysis Study (ASCEND-D). Am J Nephrol 2023; 54:1-13. [PMID: 36739866 DOI: 10.1159/000528696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/23/2022] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Hyporesponsiveness to erythropoiesis-stimulating agents (ESAs) affects 10-15% of the chronic dialysis population. We explored baseline characteristics and predictors of ESA hyporesponsiveness in a global randomized cardiovascular outcomes study comparing an investigational hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI), daprodustat, with conventional ESA treatment. METHODS ASCEND-D (NCT02879305) recruited 2964 chronic dialysis patients receiving ESA treatment (standardized to weekly intravenous [IV] epoetin) who were iron replete at baseline. The primary ESA hyporesponsiveness definition was an ESA Resistance Index (ERI, ESA Units/kg/week/hemoglobin g/l) ≥2 or IV standardized ESA dose ≥450 Units/kg/week. Predictors of ESA hyporesponsiveness were determined using a multivariable regression model. Alternative hyporesponder definitions were explored. RESULTS Using the primary definition, 354 (12%) patients were ESA hyporesponsive. Geographic region, notably Latin America, lower baseline body mass index and transferrin saturation, younger age, lower albumin concentration, and a higher baseline IV iron dose were identified as strongly associated (P < 0.001) with ESA hyporesponsiveness. Additional predictors of ESA hyporesponsiveness included female sex (P = 0.010), history of heart failure (P = 0.035), longer dialysis vintage (P = 0.077), smoking status (P = 0.247), aspirin use (P = 0.121), and angiotensin-converting enzyme inhibitor/ angiotensin receptor blocker use (P = 0.214). CONCLUSION This is the first global HIF-PHI study to report pre-specified definitions and predictors of ESA hyporesponsiveness. While most of the predictors identified in our study have been previously reported, geographic region stands out as an unexpected finding, meriting further investigation.
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Van Hout MC, Bigland C, Marsden A, Bangura A, Ngcobo F, Mponela LM, McMahon G. Precarious migrants and COVID-19 responses: leave no one behind. Public Health 2022; 207:e1-e2. [PMID: 35469659 PMCID: PMC8940564 DOI: 10.1016/j.puhe.2022.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/13/2022] [Indexed: 11/29/2022]
Affiliation(s)
- M-C Van Hout
- Public Health Institute, Liverpool John Moores University, Liverpool, UK.
| | - C Bigland
- Public Health Institute, Liverpool John Moores University, Liverpool, UK
| | - A Marsden
- Refugee and Asylum Seeker Participatory Action Research, Manchester, UK
| | - A Bangura
- Refugee and Asylum Seeker Participatory Action Research, Manchester, UK
| | - F Ngcobo
- Refugee and Asylum Seeker Participatory Action Research, Manchester, UK
| | - L M Mponela
- Refugee and Asylum Seeker Participatory Action Research, Manchester, UK
| | - G McMahon
- Refugee and Asylum Seeker Participatory Action Research, Manchester, UK
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Kelly YP, Mistry K, Ahmed S, Shaykevich S, Desai S, Lipsitz SR, Leaf DE, Mandel EI, Robinson E, McMahon G, Czarnecki PG, Charytan DM, Waikar SS, Mendu ML. Controlled Study of Decision-Making Algorithms for Kidney Replacement Therapy Initiation in Acute Kidney Injury. Clin J Am Soc Nephrol 2022; 17:194-204. [PMID: 34911731 PMCID: PMC8823944 DOI: 10.2215/cjn.02060221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 02/09/2021] [Accepted: 12/08/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND AND OBJECTIVES AKI requiring KRT is associated with high mortality and utilization. We evaluated the use of an AKI Standardized Clinical Assessment and Management Plan (SCAMP) on patient outcomes, including mortality, hospital length of stay, and intensive care unit length of stay. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We conducted a 12-month controlled study in the intensive care units of a large academic tertiary medical center. We alternated use of the AKI-SCAMP with use of a "sham" control form in 4- to 6-week blocks. The primary outcome was risk of inpatient mortality. Prespecified secondary outcomes included 30- and 60-day mortality, hospital length of stay, and intensive care unit length of stay. Generalized estimating equations were used to estimate the effect of the AKI-SCAMP on mortality and length of stay. RESULTS There were 122 patients in the AKI-SCAMP group and 102 patients in the control group. There was no significant difference in inpatient mortality associated with AKI-SCAMP use (41% versus 47% control). AKI-SCAMP use was associated with significantly reduced intensive care unit length of stay (mean, 8; 95% confidence interval, 8 to 9 days versus mean, 12; 95% confidence interval, 10 to 13 days; P<0.001) and hospital length of stay (mean, 25; 95% confidence interval, 22 to 29 days versus mean, 30; 95% confidence interval, 27 to 34 days; P=0.02). Patients in the AKI-SCAMP group were less likely to receive KRT in the context of physician-perceived treatment futility than those in the control group (2% versus 7%; P=0.003). CONCLUSIONS Use of the AKI-SCAMP tool for AKI KRT was not significantly associated with inpatient mortality, but was associated with reduced intensive care unit length of stay, hospital length of stay, and use of KRT in cases of physician-perceived treatment futility. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER Acute Kidney Injury Standardized Clinical Assessment and Management Plan for Renal Replacement Initiation, NCT03368183. PODCAST This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_02_07_CJN02060221.mp3.
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Affiliation(s)
- Yvelynne P. Kelly
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Kavita Mistry
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Salman Ahmed
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Shimon Shaykevich
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sonali Desai
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Department of the Chief Medical Officer, Brigham and Women's Hospital, Boston, Massachusetts
| | - Stuart R. Lipsitz
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - David E. Leaf
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ernest I. Mandel
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Emily Robinson
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Gearoid McMahon
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Peter G. Czarnecki
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - David M. Charytan
- Nephrology Division, New York University Grossman School of Medicine, New York, New York
| | - Sushrut S. Waikar
- Section of Nephrology, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts
| | - Mallika L. Mendu
- Division of Renal Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Department of the Chief Medical Officer, Brigham and Women's Hospital, Boston, Massachusetts
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Schofield BJ, Andreani NA, Günther CS, Law GR, McMahon G, Swainson M, Goddard MR. Livestock microbial landscape patterns: Retail poultry microbiomes significantly vary by region and season. Food Microbiol 2022; 101:103878. [PMID: 34579846 PMCID: PMC8494115 DOI: 10.1016/j.fm.2021.103878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/18/2020] [Accepted: 08/02/2021] [Indexed: 11/21/2022]
Abstract
Microbes play key roles in animal welfare and food safety but there is little understanding of whether microbiomes associated with livestock vary in space and time. Here we analysed the bacteria associated with the carcasses of the same breed of 28 poultry broiler flocks at different stages of processing across two climatically similar UK regions over two seasons with 16S metabarcode DNA sequencing. Numbers of taxa types did not differ by region, but did by season (P = 1.2 × 10-19), and numbers increased with factory processing, especially in summer. There was also a significant (P < 1 × 10-4) difference in the presences and abundances of taxa types by season, region and factory processing stage, and the signal for seasonal and regional differences remained highly significant on final retail products. This study therefore revealed that both season and region influence the types and abundances of taxa on retail poultry products. That poultry microbiomes differ in space and time should be considered when testing the efficacy of microbial management interventions designed to increase animal welfare and food safety: these may have differential effects on livestock depending on location and timing.
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Affiliation(s)
- B J Schofield
- School of Life Sciences, University of Lincoln, Lincolnshire, United Kingdom
| | - N A Andreani
- School of Life Sciences, University of Lincoln, Lincolnshire, United Kingdom
| | - C S Günther
- School of Life Sciences, University of Lincoln, Lincolnshire, United Kingdom
| | - G R Law
- School of Health and Social Care, University of Lincoln, Lincolnshire, United Kingdom
| | - G McMahon
- Moy Park Ltd., Craigavon, Co. Armagh, United Kingdom
| | - M Swainson
- National Centre for Food Manufacturing, University of Lincoln, Lincolnshire, United Kingdom
| | - M R Goddard
- School of Life Sciences, University of Lincoln, Lincolnshire, United Kingdom.
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Kilgallon JL, Gannon M, Burns Z, McMahon G, Dykes P, Linder J, Bates DW, Waikar S, Lipsitz S, Baer HJ, Samal L. Multicomponent intervention to improve blood pressure management in chronic kidney disease: a protocol for a pragmatic clinical trial. BMJ Open 2021; 11:e054065. [PMID: 34937722 PMCID: PMC8705218 DOI: 10.1136/bmjopen-2021-054065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION The purpose of this study is to incorporate behavioural economic principles and user-centred design principles into a multicomponent intervention for the management of uncontrolled hypertension (HTN) in chronic kidney disease (CKD) in primary care. METHODS AND ANALYSIS This is a multicentre, pragmatic, controlled trial cluster-randomised at the clinician level at The Brigham and Women's Practice -Based Research Network of 15 practices. Of 220 total clinicians, 184 were eligible to be enrolled, and the remainder were excluded (residents and clinicians who see urgent care or walk-in patients); no clinicians opted out. The intervention consists of a clinical decision support system based in behavioural economic and user-centred design principles that will: (1) synthesise existing laboratory tests, medication orders and vital sign data; (2) increase recognition of CKD, (3) increase recognition of uncontrolled HTN in CKD patients and (4) deliver evidence-based CKD and HTN management recommendations. The primary endpoint is the change in mean systolic blood pressure between baseline and 6 months compared across arms. We will use the Reach Effectiveness Adoption Implementation Maintenance framework. At the conclusion of this study, we will have: (1) validated an intervention that combines laboratory tests, medication records and clinical information collected by electronic health records to recognise uncontrolled HTN in CKD patients and recommend a course of care, (2) tested the effectiveness of said intervention and (3) collected information about the implementation of the intervention that will aid in dissemination of the intervention to other practice settings. ETHICS AND DISSEMINATION The Human Subjects Institutional Review Board at Brigham and Women's Hospital provided an expedited review and approval for this study protocol, and a Data Safety Monitoring Board will ensure the ongoing safety of the trial. TRIAL REGISTRATION NUMBER NCT03679247.
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Affiliation(s)
- John L Kilgallon
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Michael Gannon
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Zoe Burns
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Gearoid McMahon
- Division of Nephrology, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Patricia Dykes
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey Linder
- Division of General Internal Medicine and Geriatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - David Westfall Bates
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Sushrut Waikar
- Nephrology, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Stuart Lipsitz
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Heather J Baer
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Lipika Samal
- Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
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Edge L, Cunningham C, Murphy N, Dillon A, Flynn S, O'Shaughnessy Í, Davis A, O'Rourke B, Brossier L, Doran C, Hennessy A, Kennedy U, McMahon G, McNamara R, Shields D, Staunton P, Horgan F. 142 FRAILTY IDENTIFICATION AND INTERDISCIPLINARY ASSESSMENT OF OLDER PEOPLE IN THE EMERGENCY DEPARTMENT. Age Ageing 2021. [DOI: 10.1093/ageing/afab219.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Abstract
Background
Older People are attending Emergency Departments (EDs) in increasing numbers but the optimal assessment measures to use have yet to be established. This study examined the clinical utility of different assessments of strength, functional mobility, sarcopenia, cognition and frailty used by the physiotherapist in an interdisciplinary team (IDT) in the ED and determined any associations with clinical outcomes.
Methods
This observational cross-sectional study recruited adults ≥70 years who were assessed by an IDT on weekdays during working hours. Demographic variables such as age, gender, social situation, baseline mobility, falls and clinical measures such as Clinical Frailty Scale (CFS), 4AT, hand-held dynamometry, calf circumference and functional mobility in ED were recorded. Clinical outcomes were admission to hospital, discharge from ED with onward referral (ambulatory care or community) and discharge from ED with no referral. Ethical approval was obtained and SPSS was used for statistical analysis.
Results
Two hundred and fifty four participants were recruited, 58.3% female, mean age 80.23 (SD 6.56). Median CFS was 4 (IRQ 2.0), range 1–7 with 32.7% (n = 83) considered frail. Sarcopenia prevalence was 89.3% using grip strength and 7.1% using calf circumference. Grip strength predicted frailty even after adjusting for age (p < 0.0001), gender (p < 0.0001) and falls (p = 0.043). Admission to hospital was predicted by major diagnostic category (p = 0.016) and inability to sit to stand independently in ED (p < 0.0001). Seventy percent (n = 179) of participants were discharged from ED, with 27.6% referred to ambulatory care or community services. Onward referral was predicted by frailty (p = 0.016) and falls in the last six months (p = 0.028).
Conclusion
Grip strength in addition to a validated tool such as CFS may assist an experienced IDT in identifying frailty, which can in turn inform decision-making regarding ED disposition and pathways of care for older people. Functional assessment in the ED is also important to determine the need for hospital admission.
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Affiliation(s)
- L Edge
- St James's Hospital , Dublin, Ireland
| | | | - N Murphy
- St James's Hospital , Dublin, Ireland
| | - A Dillon
- St James's Hospital , Dublin, Ireland
| | - S Flynn
- St James's Hospital , Dublin, Ireland
| | | | - A Davis
- St James's Hospital , Dublin, Ireland
| | - B O'Rourke
- Royal College of Surgeons in Ireland , Dublin, Ireland
| | - L Brossier
- Royal College of Surgeons in Ireland , Dublin, Ireland
| | - C Doran
- Royal College of Surgeons in Ireland , Dublin, Ireland
| | | | - U Kennedy
- St James's Hospital , Dublin, Ireland
| | - G McMahon
- St James's Hospital , Dublin, Ireland
| | | | - D Shields
- St James's Hospital , Dublin, Ireland
| | | | - F Horgan
- Royal College of Surgeons in Ireland , Dublin, Ireland
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8
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Howley F, Lavan A, McMahon G, Mehmood M, Briggs R. 162 TRENDS IN EMERGENCY DEPARTMENT USE BY OLDER PEOPLE DURING THE COVID-19 PANDEMIC. Age Ageing 2021. [PMCID: PMC8690002 DOI: 10.1093/ageing/afab216.162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background Older people have been disproportionately affected by the COVID-19 pandemic with reports suggesting that many older people deferred seeking healthcare during the pandemic due to fear of contracting COVID-19. The aim of this study was to examine trends of emergency department (ED) use by older people during the first wave of the COVID-19 pandemic compared to previous years. Methods The study site is a 1,000-bed university teaching hospital with annual ED new-patient attendance of >50,000. All ED presentations of patients aged ≥70 years from March–August 2020, 2019 and 2018 inclusive (n = 13,989) were reviewed and compared for presenting complaint, Manchester Triage Score, and admission/discharge decision. Results There was a 16% reduction in presentations across the 6 months in 2020 compared to the average of 2018/2019. On average 4 fewer people aged ≥70 years presented to the ED per day in 2020. Much of this was concentrated in March (33% fewer presentations) and April (31% fewer presentations), when the country was in ‘lockdown’, i.e. non-essential journeys were banned. There was a 20% reduction in patients presenting with stroke and cardiac complaints. In the three months following easing of restrictions, there was a 25% increase in falls and orthopaedic injuries when compared to 2018/2019. Conclusion This study demonstrates a significant decline in the number of older people presenting to the ED for unscheduled care, including for potentially time-dependent illnesses such as stroke or cardiac complaints. Presenting to the ED remains the most frequent route by which unwell older people access acute hospital care and it is vitally important that they continue to do so in a timely manner when necessary. Given the possibility of further lockdowns and restrictions, this message needs to be communicated to older people clearly by healthcare professionals and governmental bodies to mitigate against adverse outcomes related to delayed or deferred care.
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Affiliation(s)
- F Howley
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland,Department of Emergency Medicine, St James's Hospital, Dublin, Ireland
| | - A Lavan
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - G McMahon
- Department of Emergency Medicine, St James's Hospital, Dublin, Ireland
| | - M Mehmood
- Department of Emergency Medicine, St James's Hospital, Dublin, Ireland
| | - R Briggs
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
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Abstract
Multi-isotope imaging mass spectrometry (MIMS) allows the measurement of turnover of molecules within intracellular compartments with a spatial resolution down to 30 nm. We use molecules enriched in stable isotopes administered to animals by diet or injection, or to cells through the culture medium. The stable isotopes used are, in general, 15 N, 13 C, 18 O, and 2 H. For stem cell studies, we essentially use 15 N-thymidine, 13 C-thymidine, and 81 Br from BrdU. This protocol describes the practical use of MIMS with specific reference to applications in stem cell research. This includes choice and administration of stable isotope label(s), sample preparation, best practice for high-resolution imaging, secondary ion mass spectrometry using the Cameca NanoSIMS 50L, and methods for robust statistical analysis of label incorporation in regions of interest (ROI). © 2021 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Stable isotope labeling of DNA in cultured cells Basic Protocol 2: Stable isotope labeling of DNA in animals Basic Protocol 3: Preparation of Si chips, the general sample support for NanoSIMS analysis Basic Protocol 4: Stable isotope analysis of DNA replication in single nuclei in a population of cells with NanoSIMS Basic Protocol 5: Data reduction and processing.
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Affiliation(s)
- G. McMahon
- National Physical Laboratory, Teddington UK
| | - C.P. Lechene
- Division of Genetics, Brigham and Women’s Hospital and Harvard Medical School, Boston MA USA
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Jusmanova K, Rice C, Bourke R, Lavan A, McMahon G, Cunningham C, Kenny RA, Briggs R. Letter to the editor, reply re: 'Impact of a specialist service in the emergency department on admission, length of stay and readmission of patients presenting with falls, syncope and dizziness'. QJM 2021; 114:349-350. [PMID: 33823036 DOI: 10.1093/qjmed/hcab068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Indexed: 11/12/2022] Open
Affiliation(s)
- K Jusmanova
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
| | - C Rice
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R Bourke
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
| | - A Lavan
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
| | - G McMahon
- Department of Emergency Medicine, St James's Hospital, Dublin, Ireland
| | - C Cunningham
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R A Kenny
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R Briggs
- Falls & Syncope Unit, Mercer's Institute for Successful Ageing, St James's Hospital, James's St, Dublin 8, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
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11
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Steele P, McMahon J, Dickson K, Zubair F, Puglia F, McMahon G, Wales C, McCaul J, Ansell M, Hislop S, Thomson E, Subramaniam S. Applying the British Association of Oral and Maxillofacial Surgeons quality outcomes metrics to a UK oncology and reconstructive surgery service - benchmarking the data. Br J Oral Maxillofac Surg 2021; 59:1079-1084. [PMID: 34275677 DOI: 10.1016/j.bjoms.2021.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 03/16/2021] [Indexed: 11/15/2022]
Abstract
The British Association of Oral and Maxillofacial Surgery is soon to implement the Quality Outcomes in Oral in Maxillofacial Surgery (QOMS) to provide a platform for quality management across the specialty in the UK. The initial oncology and reconstruction audits for QOMS involves data collection on specific procedures and metrics. The aim of this report is to determine their appropriateness using extant audit datasets in our institution that overlap substantially with the QOMS audits. Pre-existing datasets comprising information on patients treated for oral cavity SCC with curative intent were analysed. Data on surgical margins, lymphadenectomy lymph node yield, delay between surgery and adjuvant radiotherapy, duration of hospital stay, and complications including flap failures were analysed. All statistical analyses were performed with SPSS 25. Run charts describing longitudinal data were generated using SPC for Excel version 6. Twenty three patients (3.1%) of 701 resections had a positive surgical margin reported. Seventeen (4.3%) of patients had less than 18 LNs in the ND specimen analysed. Mean time to start date of adjuvant therapy was 62 days. Only 9% of patients commenced adjuvant therapy within 6 weeks. The median duration of stay was 18 days. In 1153 free flaps a failure rate of 4.3% was identified. A total of 1349 complications (CD I-V) were recorded in the 1111 patients undergoing major surgery with free flap reconstruction. The QOMS selected metrics for oncology and reconstruction are clinically relevant, readily measurable, and likely to be actionable by the surgical team.
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Affiliation(s)
- P Steele
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - J McMahon
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - K Dickson
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - F Zubair
- University of Glasgow Medical School, Faculty of Life Sciences, United Kingdom.
| | - F Puglia
- BAOMS Royal College of Surgeons of England, 35/43 Lincoln's Inn Fields, London, United Kingdom.
| | - G McMahon
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - C Wales
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - J McCaul
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - M Ansell
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - S Hislop
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - E Thomson
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
| | - S Subramaniam
- Oral and Maxillofacial Surgery Department, Queen Elizabeth University Hospital Glasgow, United Kingdom.
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Jusmanova K, Rice C, Bourke R, Lavan A, McMahon G, Cunningham C, Kenny RA, Briggs R. Response: Impact of a specialist service in the emergency department on admission, length of stay and readmission of patients presenting with falls, syncope and dizziness. QJM 2021; 114:78-79. [PMID: 33237312 DOI: 10.1093/qjmed/hcaa315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- K Jusmanova
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - C Rice
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R Bourke
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - A Lavan
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - G McMahon
- Department of Emergency Medicine, St James's Hospital, Dublin, Ireland
| | - C Cunningham
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R A Kenny
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
| | - R Briggs
- Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
- Department of Medical Gerontology, Trinity College Dublin, Dublin, Ireland
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13
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McMahon G, Rogers A, Woulfe Z, Tuthill E, Doyle M, Burke G, Imcha M. Women's Opinions on Cardiotocograph Monitoring and Staff Communication During Labour. Ir Med J 2019; 112:1022. [PMID: 32311252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- G McMahon
- Dept. of Obstetrics and Gynaecology, University Maternity Hospital Limerick, Ireland
| | - A Rogers
- Labour Ward, University Maternity Hospital Limerick, Ireland
| | - Z Woulfe
- Labour Ward, University Maternity Hospital Limerick, Ireland
| | - E Tuthill
- Dept. of Obstetrics and Gynaecology, University Maternity Hospital Limerick, Ireland
| | - M Doyle
- Labour Ward, University Maternity Hospital Limerick, Ireland
| | - G Burke
- Dept. of Obstetrics and Gynaecology, University Maternity Hospital Limerick, Ireland
| | - M Imcha
- Dept. of Obstetrics and Gynaecology, University Maternity Hospital Limerick, Ireland
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14
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Santos M, McMahon G, Castelo Branco M, Silva R, Donato P, Domingues C, Marinho A, Alves P, Gomes A, Martins R, Pego M, Goncalves L, Ferreira M. P4348Increased renal artery 18F-NaF uptake is associated with reduced with glomerular filtration rate: an exploratory analysis in subjects with no manifest cardiovascular disease. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx504.p4348] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Appleby N, Groarke E, Crowley M, Wahab FA, McCann AM, Egan L, Gough D, McMahon G, O'Donghaile D, O'Keeffe D, O'Connell N. Reversal of warfarin anticoagulation using prothrombin complex concentrate at 25 IU kg−1: results of the RAPID study. Transfus Med 2016; 27:66-71. [DOI: 10.1111/tme.12371] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/19/2016] [Accepted: 09/19/2016] [Indexed: 11/27/2022]
Affiliation(s)
- N. Appleby
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - E. Groarke
- Department of Haematology; Limerick University Hospital; Limerick Ireland
| | - M. Crowley
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - F. A. Wahab
- Department of Haematology; Limerick University Hospital; Limerick Ireland
| | - A. M. McCann
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - L. Egan
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - D. Gough
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - G. McMahon
- Department of Emergency Medicine; St. James's University Hospital; Dublin Ireland
| | - D. O'Donghaile
- Department of Haematology; St James's University Hospital; Dublin Ireland
| | - D. O'Keeffe
- Department of Haematology; Limerick University Hospital; Limerick Ireland
| | - N. O'Connell
- Department of Haematology; St James's University Hospital; Dublin Ireland
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Papineau D, De Gregorio B, Fearn S, Kilcoyne D, McMahon G, Purohit R, Fogel M. Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India. Geobiology 2016; 14:3-32. [PMID: 26490161 DOI: 10.1111/gbi.12164] [Citation(s) in RCA: 6] [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] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 09/02/2015] [Indexed: 06/05/2023]
Abstract
Stromatolites composed of apatite occur in post-Lomagundi-Jatuli successions (late Palaeoproterozoic) and suggest the emergence of novel types of biomineralization at that time. The microscopic and nanoscopic petrology of organic matter in stromatolitic phosphorites might provide insights into the suite of diagenetic processes that formed these types of stromatolites. Correlated geochemical micro-analyses of the organic matter could also yield molecular, elemental and isotopic compositions and thus insights into the role of specific micro-organisms among these communities. Here, we report on the occurrence of nanoscopic disseminated organic matter in the Palaeoproterozoic stromatolitic phosphorite from the Aravalli Supergroup of north-west India. Organic petrography by micro-Raman and Transmission Electron Microscopy demonstrates syngeneity of the organic matter. Total organic carbon contents of these stromatolitic phosphorite columns are between 0.05 and 3.0 wt% and have a large range of δ(13) Corg values with an average of -18.5‰ (1σ = 4.5‰). δ(15) N values of decarbonated rock powders are between -1.2 and +2.7‰. These isotopic compositions point to the important role of biological N2 -fixation and CO2 -fixation by the pentose phosphate pathway consistent with a population of cyanobacteria. Microscopic spheroidal grains of apatite (MSGA) occur in association with calcite microspar in microbial mats from stromatolite columns and with chert in the core of diagenetic apatite rosettes. Organic matter extracted from the stromatolitic phosphorites contains a range of molecular functional group (e.g. carboxylic acid, alcohol, and aliphatic hydrocarbons) as well as nitrile and nitro groups as determined from C- and N-XANES spectra. The presence of organic nitrogen was independently confirmed by a CN(-) peak detected by ToF-SIMS. Nanoscale petrography and geochemistry allow for a refinement of the formation model for the accretion and phototrophic growth of stromatolites. The original microbial biomass is inferred to have been dominated by cyanobacteria, which might be an important contributor of organic matter in shallow-marine phosphorites.
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Affiliation(s)
- D Papineau
- London Centre for Nanotechnology, University College London, London, UK
- Department of Earth Sciences, University College London, London, UK
| | - B De Gregorio
- Material Science and Technology Division, Naval Research Laboratory, Washington, DC, USA
| | - S Fearn
- Department of Material Sciences, Imperial College, London, UK
| | - D Kilcoyne
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - G McMahon
- School of Materials, The University of Manchester, Manchester, UK
| | - R Purohit
- Department of Geology, Government College Sirohi, Sirohi, Rajasthan, India
| | - M Fogel
- University of California at Merced, Merced, CA, USA
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17
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Eltweri AM, McMahon G, Gravante G. The use of tonsil swabs in laparoscopic surgery. Ann R Coll Surg Engl 2014; 96:631-2. [PMID: 25350201 DOI: 10.1308/rcsann.2014.96.8.631] [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: 11/22/2022] Open
Affiliation(s)
- A M Eltweri
- University Hospitals of Leicester NHS Trust, UK
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18
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Morley D, McNamara P, Kennelly S, McMahon G, Bergin C. Limitations to the identification of HIV-associated neurocognitive disorders in clinical practice. HIV Med 2013; 14:497-502. [PMID: 23594179 DOI: 10.1111/hiv.12036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVES The objective of this study was to establish the level of awareness of HAND among healthcare providers, the screening tools that are currently used in its detection and factors that limit cognitive assessments. METHODS We distributed a 12-item questionnaire to doctors and nurses who work in the Department of Genitourinary Medicine and Infectious Disease (GUIDE) service and also to doctors who work in the emergency department (ED) at St James Hospital. RESULTS 35 surveys were collected, 54% (n = 19) from the GUIDE service and 46% (n = 16) from the ED. 82% (n = 29) of participants were doctors from interns to consultants. There was reasonable appreciation among participants with regards the prevalence of neurocognitive impairment (estimated at 29.1% among patients on HAART, and 39.3% among patients not on HAART). Screening tools were rarely used by GUIDE and ED clinicians (25% vs. 15% of the time). The Mini Mental State Examination (MMSE) was previously used by 37% (n = 13) of the group. Very few people had used the HIV Dementia Scale (HIVDS) 6% (n = 2). 34% of respondents felt that 'Orientation in Person, Place and Time was a sufficient screening tool for cognitive assessment'. Lack of time, exposed environment and lack of availability of screening tool were cited as limitations to cognitive screening in the ED environment. CONCLUSIONS This study examines awareness of HAND among healthcare providers and also reasons for inadequate assessment. There is a need for consensus on screening guidelines. A quick, easy to use and readily available screening tool may have a role in the acute setting in identifying high-risk patients.
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Affiliation(s)
- D Morley
- Infectious Disease, Cork University Hospital, Cork, Ireland.
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19
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Rizal B, Ye F, Dhakal P, Chiles TC, Shepard S, McMahon G, Burns MJ, Naughton MJ. Imprint-Templated Nanocoax Array Architecture: Fabrication and Utilization. NATO Science for Peace and Security Series B: Physics and Biophysics 2013. [DOI: 10.1007/978-94-007-5313-6_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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20
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Cox RF, Hernandez-Santana A, Ramdass S, McMahon G, Harmey JH, Morgan MP. Microcalcifications in breast cancer: novel insights into the molecular mechanism and functional consequence of mammary mineralisation. Br J Cancer 2012; 106:525-37. [PMID: 22233923 PMCID: PMC3273345 DOI: 10.1038/bjc.2011.583] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mammographic microcalcifications represent one of the most reliable features of nonpalpable breast cancer yet remain largely unexplored and poorly understood. METHODS We report a novel model to investigate the in vitro mineralisation potential of a panel of mammary cell lines. Primary mammary tumours were produced by implanting tumourigenic cells into the mammary fat pads of female BALB/c mice. RESULTS Hydroxyapatite (HA) was deposited only by the tumourigenic cell lines, indicating mineralisation potential may be associated with cell phenotype in this in vitro model. We propose a mechanism for mammary mineralisation, which suggests that the balance between enhancers and inhibitors of physiological mineralisation are disrupted. Inhibition of alkaline phosphatase and phosphate transport prevented mineralisation, demonstrating that mineralisation is an active cell-mediated process. Hydroxyapatite was found to enhance in vitro tumour cell migration, while calcium oxalate had no effect, highlighting potential consequences of calcium deposition. In addition, HA was also deposited in primary mammary tumours produced by implanting the tumourigenic cells into the mammary fat pads of female BALB/c mice. CONCLUSION This work indicates that formation of mammary HA is a cell-specific regulated process, which creates an osteomimetic niche potentially enhancing breast tumour progression. Our findings point to the cells mineralisation potential and the microenvironment regulating it, as a significant feature of breast tumour development.
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Affiliation(s)
- R F Cox
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
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21
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Abstract
The mammalian target of rapamycin (mTOR) plays a key role in the immune response. mTOR inhibitors suppress T cell activation and proliferation and are effective immunosuppressants. Today there is growing interest in their potential role in inducing tolerance after transplantation. mTOR inhibitors induce anergy in naïve T cells, promote the expansion of regulatory T cells, and inhibit the maturation of dendritic cells, thus promoting immunologic tolerance. Here we review the mechanisms by which mTOR inhibitors promote tolerance. We discuss the clinical relevance of these mechanisms and suggest how they might be used in the design of future protocols to induce tolerance.
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Affiliation(s)
- Gearoid McMahon
- Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA.
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22
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Fox D, O’Connor R, Mallon P, McMahon G. Development of a single-tube, low-cost, analytical process to extract, separate and determine efavirenz and rifampicin plasma concentrations in HIV/TB co-infected patients. J Int AIDS Soc 2010. [PMCID: PMC3112926 DOI: 10.1186/1758-2652-13-s4-p149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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23
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Lacey C, McMahon G, Bones J, Barron L, Morrissey A, Tobin J. An LC–MS method for the determination of pharmaceutical compounds in wastewater treatment plant influent and effluent samples. Talanta 2008; 75:1089-97. [DOI: 10.1016/j.talanta.2008.01.011] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 12/17/2007] [Accepted: 01/07/2008] [Indexed: 11/29/2022]
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24
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O'Connell B, McMahon G, Kelleher M, Rossney AS. Meticillin-resistant Staphylococcus aureus blood-stream infection among patients attending the emergency department of an urban tertiary-referral hospital. Ir Med J 2007; 100:433-5. [PMID: 17566479] [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] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Meticillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen but reports of community-acquired (CA) MRSA are increasing. This study determined the incidence of MRSA-blood-stream infection (BSI) among patients attending the Emergency Department (ED) of an urban tertiary-referral hospital between January 2004 and September 2005, the proportion of cases that were CA or health-care associated (HCA), the epidemiological types of isolates and the presence of pvl genes in CA-MRSA. Eighteen patients presented with MRSA-BSI; 16 cases were categorised as HCA and two as CA. Most patients were male, elderly and lived locally. Two patients (aged <30 years) had no recent previous HC exposure. Only one patient received appropriate empiric antimicrobial therapy. Isolates from patients with HCA-MRSA were similar to the predominant MRSA strain in Irish hospitals. The two CA-MRSA isolates exhibited different epidemiological types; one was pvl-positive. A significant cohort of patients present to the ED with MRSA-BSI. Careful consideration of appropriate empiric antimicrobial therapy for suspected staphylococcal infection is required.
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Affiliation(s)
- B O'Connell
- Microbiology Department, St. James's Hospital, James's Street, Dublin.
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25
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McMahon G, Saint-Cyr HF, Lechene C, Unkefer CJ. CN- secondary ions form by recombination as demonstrated using multi-isotope mass spectrometry of 13C- and 15N-labeled polyglycine. J Am Soc Mass Spectrom 2006; 17:1181-7. [PMID: 16750387 DOI: 10.1016/j.jasms.2006.04.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 04/01/2006] [Accepted: 04/08/2006] [Indexed: 05/10/2023]
Abstract
We have studied the mechanism of formation CN- secondary ions under Cs+ primary ion bombardment. We have synthesized 13C and 15N labeled polyglycine samples with the distance between the two labels and the local atomic environment of the 13C label systematically varied. We have measured four masses in parallel: 12C, 13C, and two of 12C14N, 13C14N, 12C15N, and 13C15N. We have calculated the 13C/12C isotope ratio, and the different combinations of the CN isotope ratios (27CN/26CN, 28CN/27CN, and 28CN/26CN). We have measured a high 13C15N- secondary ion current from the 13C and 15N labeled polyglycines, even when the 13C and 15N labels are separated. By comparing the magnitude of the varied combinations of isotope ratios among the samples with different labeling positions, we conclude the following: CN- formation is in large fraction due to recombination of C and N; the CO double bond decreases the extent of CN- formation compared to the case where carbon is singly bonded to two hydrogen atoms; and double-labeling with 13C and 15N allows us to detect with high sensitivity the molecular ion 13C15N-.
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Affiliation(s)
- G McMahon
- National Resource for Imaging Mass Spectrometry, Harvard Medical School and Brigham and Women's Hospital, Cambridge, Massachusetts 02139, USA
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26
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Murray-Lillibridge K, Barry J, Reagan S, O'flanagan D, Sayers G, Bergin C, Keenan E, O'briain S, Plunkett P, McMahon G, Keane C, O'sullivan P, Igoe D, Mullen L, Ward M, Smith A, Fischer M. Epidemiological findings and medical, legal, and public health challenges of an investigation of severe soft tissue infections and deaths among injecting drug users -- Ireland, 2000. Epidemiol Infect 2005; 134:894-901. [PMID: 16316497 PMCID: PMC2870441 DOI: 10.1017/s0950268805005418] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2005] [Indexed: 11/05/2022] Open
Abstract
In May 2000, public health authorities in Dublin, Ireland, identified a cluster of unexplained severe illness among injecting drug users (IDUs). Similar clusters were also reported in Scotland and England. Concurrent investigations were undertaken to identify the aetiology and source of the illnesses. In Dublin, 22 IDUs were identified with injection-site inflammation resulting in hospitalization or death; eight (36%) died. Common clinical findings among patients with severe systemic symptoms included leukaemoid reaction and cardiogenic shock. Seventeen (77%) patients reported injecting heroin intramuscularly in the 2 weeks before illness. Of 11 patients with adequate specimens available for testing, two (18%) were positive by 16S rDNA PCR for Clostridium novyi. Clinical and laboratory findings suggested that histotoxic Clostridia caused a subset of infections in these related clusters. Empiric treatment for infections among IDUs was optimized for anaerobic organisms, and outreach led to increased enrolment in methadone treatment in Dublin. Many unique legal, medical, and public health challenges were encountered during the investigation of this outbreak.
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27
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Patti ME, McMahon G, Mun EC, Bitton A, Holst JJ, Goldsmith J, Hanto DW, Callery M, Arky R, Nose V, Bonner-Weir S, Goldfine AB. Severe hypoglycaemia post-gastric bypass requiring partial pancreatectomy: evidence for inappropriate insulin secretion and pancreatic islet hyperplasia. Diabetologia 2005; 48:2236-40. [PMID: 16195867 DOI: 10.1007/s00125-005-1933-x] [Citation(s) in RCA: 292] [Impact Index Per Article: 15.4] [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] [Received: 04/06/2005] [Accepted: 06/13/2005] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Postprandial hypoglycaemia following gastric bypass for obesity is considered a late manifestation of the dumping syndrome and can usually be managed with dietary modification. We investigated three patients with severe postprandial hypoglycaemia and hyperinsulinaemia unresponsive to diet, octreotide and diazoxide with the aim of elucidating the pathological mechanisms involved. METHODS Glucose, insulin, and C-peptide were measured in the fasting and postprandial state, and insulin secretion was assessed following selective intra-arterial calcium injection. Pancreas histopathology was assessed in all three patients. RESULTS All three patients had evidence of severe postprandial hyperinsulinaemia and hypoglycaemia. In one patient, reversal of gastric bypass was ineffective in reversing hypoglycaemia. All three patients ultimately required partial pancreatectomy for control of neuroglycopenia; pancreas pathology of all patients revealed diffuse islet hyperplasia and expansion of beta cell mass. CONCLUSIONS/INTERPRETATION These findings suggest that gastric bypass-induced weight loss may unmask an underlying beta cell defect or contribute to pathological islet hyperplasia, perhaps via glucagon-like peptide 1-mediated pathways.
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Affiliation(s)
- M E Patti
- Research Division, Joslin Diabetes Center, Boston, MA 02215, USA.
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Schueneman A, Himmelfarb E, Geng L, Donnelly E, McMahon G, Laird D, Choy H, Hallahan D. Tyrosine kinase inhibition prevents tumor regrowth following fractionated irradiation of murine tumor models. Int J Radiat Oncol Biol Phys 2003. [DOI: 10.1016/s0360-3016(03)01156-8] [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: 11/24/2022]
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29
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McMahon G. Characterisation of the ester-substituted products of the reaction of p-t-butyl calix[4]arene and ethyl bromoacetate using LC-UV-MS and LC-DAD. Talanta 2002; 57:1119-32. [DOI: 10.1016/s0039-9140(02)00153-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2001] [Revised: 04/08/2002] [Accepted: 04/08/2002] [Indexed: 11/26/2022]
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30
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Melter M, Exeni A, Reinders ME, Fang JC, McMahon G, Ganz P, Hancock WW, Briscoe DM. Expression of the chemokine receptor CXCR3 and its ligand IP-10 during human cardiac allograft rejection. Circulation 2001; 104:2558-64. [PMID: 11714650 DOI: 10.1161/hc4601.098010] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [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: 01/19/2023]
Abstract
BACKGROUND Chemokines play an essential role in regulating the infiltration of leukocytes into allografts in experimental models. Little is known of their expression or function after human cardiac transplantation. METHODS AND RESULTS We analyzed 169 sequential human endomyocardial biopsies by immunocytochemistry for infiltration by CD3(+) T cells and the expression of the chemokine receptors CCR1, CCR3, CCR5, and CXCR3. In both cross-sectional and longitudinal analyses, the expression of each of the chemokine receptors correlated with the degree of CD3(+) T-cell infiltration. In particular, the expression of CXCR3 was temporally and spatially associated with CD3(+) T-cell infiltrates and correlated with the histopathological diagnosis of acute rejection (OR, 11.73 and 4.05, respectively; P<0.001). Of 7 patients followed up longitudinally for 1 year, 4 with consecutive biopsies developed intimal thickening by intravascular ultrasound. In these patients, there was a trend for persistent expression of CD3- and CXCR3-expressing infiltrates in the later part of the first posttransplant year. The chemokines eotaxin, IP-10, lymphotactin, MCP-1, Mig, RANTES, and SDF-1 were examined in an additional 35 biopsies by RT-PCR. Eotaxin, lymphotactin, MCP-1, Mig, and SDF-1 were present in both normal and rejecting biopsies. However, the CXCR3 ligand IP-10, which was rarely expressed in normal biopsies, was markedly induced in acute rejection (OR, 19.43; P=0.01). CONCLUSIONS The presence of CXCR3(+) T cells and the CXCR3 ligand IP-10 within endomyocardial biopsies is strongly associated with acute rejection. The CXCR3-IP-10 interaction warrants consideration as a therapeutic target in the management of cardiac allograft recipients.
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Affiliation(s)
- M Melter
- Division of Nephrology, Department of Medicine, Children's Hospital, and the Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
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Abdollahi A, Han X, Lipson K, Howlett A, McMahon G, Weber K, Krempien R, Wannenmacher M, Debus J, Huber P. Combined effects of angiogenesis inhibitors and radiation on human microvascular endothelial cells. Int J Radiat Oncol Biol Phys 2001. [DOI: 10.1016/s0360-3016(01)02236-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Solorzano CC, Jung YD, Bucana CD, McConkey DJ, Gallick GE, McMahon G, Ellis LM. In vivo intracellular signaling as a marker of antiangiogenic activity. Cancer Res 2001; 61:7048-51. [PMID: 11585733] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Alterations in endothelial cell (EC) signaling could serve as a marker of effective antiangiogenic therapy. We determined the effect of an antiangiogenic tyrosine kinase inhibitor, SU6668, on tumor EC signaling in liver metastases in mice. In vitro immunofluorescence verified that pretreatment of ECs with SU6668 before exposure to VEGF decreased in vitro phosphorylation of Erk and Akt. Using double-fluorescence immunohistochemistry, phosphorylated Erk and Akt were constitutively expressed in ECs in liver metastases in untreated mice, but SU6668 blocked activation of these signaling intermediates. Determining the activation status of the Erk and Akt signaling pathways in tumor ECs may serve as a surrogate marker for the effectiveness of antiangiogenic regimens.
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MESH Headings
- Androstadienes/pharmacology
- Angiogenesis Inhibitors/pharmacology
- Biomarkers, Tumor/physiology
- Blotting, Western
- Endothelial Growth Factors/pharmacology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/physiology
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Flavonoids/pharmacology
- Fluorescent Antibody Technique
- Humans
- Indoles/pharmacology
- Liver Neoplasms/blood supply
- Liver Neoplasms/secondary
- Lymphokines/pharmacology
- MAP Kinase Signaling System/drug effects
- MAP Kinase Signaling System/physiology
- Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/enzymology
- Neovascularization, Pathologic/physiopathology
- Oxindoles
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- Phosphorylation
- Propionates
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/antagonists & inhibitors
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Pyrroles/pharmacology
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor Protein-Tyrosine Kinases/physiology
- Receptors, Growth Factor/antagonists & inhibitors
- Receptors, Growth Factor/physiology
- Receptors, Vascular Endothelial Growth Factor
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factors
- Wortmannin
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Affiliation(s)
- C C Solorzano
- Department of Surgical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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McMahon G, Gregonis SM, Waltman SW, Omernik JM, Thorson TD, Freeouf JA, Rorick AH, Keys JE. Developing a spatial framework of common ecological regions for the conterminous United States. Environ Manage 2001; 28:293-316. [PMID: 11531234 DOI: 10.1007/s0026702429] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In 1996, nine federal agencies with mandates to inventory and manage the nation's land, water, and biological resources signed a memorandum of understanding entitled "Developing a Spatial Framework of Ecological Units of The United States." This spatial framework is the basis for interagency coordination and collaboration in the development of ecosystem management strategies. One of the objectives in this memorandum is the development of a map of common ecological regions for the conterminous United States. The regions defined in the spatial framework will be areas within which biotic, abiotic, terrestrial, and aquatic capacities and potentials are similar. The agencies agreed to begin by exploring areas of agreement and disagreement in three federal natural-resource spatial frameworks--Major Land Resource Areas of the US Department of Agriculture (USDA) Natural Resources Conservation Service, National Hierarchy of Ecological Units of the USDA Forest Service, and Level III Ecoregions of the US Environmental Protection Agency. The explicit intention is that the framework will foster an ecological understanding of the landscape, rather than an understanding based on a single resource, single discipline, or single agency perspective. This paper describes the origin, capabilities, and limitations of three major federal agency frameworks and suggests why a common ecological framework is desirable. The scientific and programmatic benefits of common ecological regions are described, and a proposed process for development of the common framework is presented.
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Affiliation(s)
- G McMahon
- US Geological Survey, Raleigh, North Carolina 27607, USA
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34
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Lane ME, Yu B, Rice A, Lipson KE, Liang C, Sun L, Tang C, McMahon G, Pestell RG, Wadler S. A novel cdk2-selective inhibitor, SU9516, induces apoptosis in colon carcinoma cells. Cancer Res 2001; 61:6170-7. [PMID: 11507069] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Recent studies have indicated that the development of cyclin-dependent kinase (cdk)2 inhibitors that deregulate E2F are a plausible pharmacological strategy for novel antineoplastic agents. We show here that 3-[1-(3H-Imidazol-4-yl)-meth-(Z)-ylidene]-5-methoxy-1,3-dihydro-indol-2-one (SU9516), a novel 3-substituted indolinone compound, binds to and selectively inhibits the activity of cdk2. This inhibition results in a time-dependent decrease (4-64%) in the phosphorylation of the retinoblastoma protein pRb, an increase in caspase-3 activation (5-84%), and alterations in cell cycle resulting in either a G(0)-G(1) or a G(2)-M block. We also report here cell line differences in the cdk-dependent phosphorylation of pRb. These findings demonstrate that SU9516 is a selective cdk2 inhibitor and support the theory that compounds that inhibit cdk2 are viable resources in the development of new antineoplastic agents.
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Affiliation(s)
- M E Lane
- Division of Oncology, Department of Medicine, Albert Einstein College of Medicine and the Albert Einstein Cancer Center, Bronx, New York 10461, USA
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35
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Kish PE, Blaivas M, Strawderman M, Muraszko KM, Ross DA, Ross BD, McMahon G. Magnetic resonance imaging of ethyl-nitrosourea-induced rat gliomas: a model for experimental therapeutics of low-grade gliomas. J Neurooncol 2001; 53:243-57. [PMID: 11718257 DOI: 10.1023/a:1012222522359] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [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: 11/12/2022]
Abstract
Human low-grade gliomas represent a population of brain tumors that remain a therapeutic challenge. Preclinical evaluation of agents, to test their preventive or therapeutic efficacy in these tumors, requires the use of animal models. Spontaneous gliomas develop in models of chemically induced carcinogenesis, such as in the transplacental N-ethyl-N-nitrosourea (ENU) rat model. However, without the ability to detect initial tumor formation, multiplicity or to measure growth rates, it is difficult to test compounds for their interventional or preventional capabilities. In this study Fisher-334 rats, treated transplacentally with ENU, underwent magnetic resonance imaging (MRI) examination in order to evaluate this approach for detection of tumor formation and growth. ENU-induced intracranial cerebral tumors were first observable in T2-weighted images beginning at 4 months of age and grew with a mean doubling time of 0.487 +/- 0.112 months. These tumors were found histologically to be predominately mixed gliomas. Two therapeutic interventions were evaluated using MRI, vitamin A (all-trans retinol palmitate, RP), as a chemopreventative agent and the anti-angiogenic drug SU-5416. RP was found to significantly delay the time to first tumor observation by one month (P = 0.05). No differences in rates of tumor formation or growth rates were observed between control and RP-treated groups. MRI studies of rats treated with SU-5416 resulted in reduction in tumor growth rates compared to matched controls. These results show that MRI can be used to provide novel information relating to the therapeutic efficacy of agents against the ENU-induced tumor model.
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Affiliation(s)
- P E Kish
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor 48109-0338, USA.
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36
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Robinson GS, Ju M, Shih SC, Xu X, McMahon G, Caldwell RB, Smith LE. Nonvascular role for VEGF: VEGFR-1, 2 activity is critical for neural retinal development. FASEB J 2001; 15:1215-7. [PMID: 11344092 DOI: 10.1096/fj.00-0598fje] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- G S Robinson
- Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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37
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Wormstone IM, Del Rio-Tsonis K, McMahon G, Tamiya S, Davies PD, Marcantonio JM, Duncan G. FGF: an autocrine regulator of human lens cell growth independent of added stimuli. Invest Ophthalmol Vis Sci 2001; 42:1305-11. [PMID: 11328744] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
PURPOSE Posterior capsule opacification (PCO) arises because of a persistent growth of lens epithelial cells. Cultured human lens cells residing on their native collagen capsule and maintained in serum-free medium actively grow and thus show an intrinsic capacity for regulation. In the present study, the authors investigated the role of the putative FGF autocrine system in human capsular bags. METHODS Capsular bags were prepared from human donor eyes and maintained in a 5% CO(2) atmosphere at 35 degrees C. On-going observations were by phase-contrast microscopy. Cellular architecture was examined by fluorescence cytochemistry. De novo protein synthesis was determined by the incorporation of 35S-methionine. Basic fibroblast growth factor (FGF) and FGF receptor (R)-1 were detected using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) techniques. FGFR-1 inhibition was achieved using the specific antagonist SU5402. RESULTS Human lens epithelial cells can maintain metabolic activity for more than 1 year in a protein-free medium. Basic FGF was shown to be present in capsular bags throughout culture and also in capsular bags removed from donor eyes that had previously undergone cataract surgery. Furthermore, FGFR-1 was identified. Inhibition of FGFR-1 caused a significant retardation of growth on the posterior capsule. On no occasion did any treated bag reach confluence, whereas all match-paired control samples did. CONCLUSIONS The results provide evidence that FGF plays an integral role in the long-term survival and growth of human lens epithelial cells, independent of external stimuli. Inhibition of FGFR-1 by specific synthetic molecules, such as SU5402, could provide a potential therapeutic approach to resolving PCO.
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Affiliation(s)
- I M Wormstone
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
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38
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Krystal GW, Honsawek S, Kiewlich D, Liang C, Vasile S, Sun L, McMahon G, Lipson KE. Indolinone tyrosine kinase inhibitors block Kit activation and growth of small cell lung cancer cells. Cancer Res 2001; 61:3660-8. [PMID: 11325836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Six indolinone tyrosine kinase inhibitors were characterized for their ability to inhibit Kit kinase and for their effects on the growth of small cell lung cancer (SCLC) cell lines. All of the six compounds were potent inhibitors of Kit kinase in a biochemical assay. A homology model of compound binding to the ATP binding site could account for the increased potency observed with the addition of a propionate moiety to the indolinone core but not the increase observed with addition of a chloride moiety. Although all of the compounds tested were potent in the biochemical assay, several exhibited significantly less potency in cellular kinase assays. Their effects on stem cell factor (SCF)-dependent Kit autophosphorylation and SCLC cell growth were also examined. Inhibition of SCF-stimulated Kit activation and cell growth in the H526 cell line was dose-dependent. At concentrations that inhibited SCF-stimulated H526 cell growth, there was little effect on insulin-like growth factor-1-stimulated growth, suggesting that these compounds exhibit reasonable selectivity for inhibition of Kit-mediated proliferation. Higher doses of the compounds were needed to inhibit serum-stimulated growth. Of the six compounds examined, SU5416 and SU6597 demonstrated the best cellular potency and, therefore, their effect on the growth of multiple SCLC cell lines in serum-containing media was examined. In addition to inhibiting proliferation, these compounds also induced significant cell death of several SCLC cell lines, but not of normal human diploid fibroblasts, in complete media. These observations suggest that Kit kinase inhibitors such as these may offer a new approach for inhibiting Kit-mediated proliferation of tumors such as SCLC, gastrointestinal stromal tumors, seminomas, and leukemias.
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Affiliation(s)
- G W Krystal
- Department of Internal Medicine, and Microbiology/Immunology,Virginia Commonwealth University, McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249, USA.
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39
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Reinmuth N, Liu W, Jung YD, Ahmad SA, Shaheen RM, Fan F, Bucana CD, McMahon G, Gallick GE, Ellis LM. Induction of VEGF in perivascular cells defines a potential paracrine mechanism for endothelial cell survival. FASEB J 2001; 15:1239-41. [PMID: 11344100 DOI: 10.1096/fj.00-0693fje] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
MESH Headings
- Animals
- Anticoagulants/pharmacology
- Apoptosis/physiology
- Becaplermin
- Cell Survival
- Cells, Cultured
- Culture Media, Conditioned
- Endothelial Growth Factors/biosynthesis
- Endothelial Growth Factors/genetics
- Endothelial Growth Factors/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Gene Expression Regulation
- Humans
- Indoles/pharmacology
- Lymphokines/biosynthesis
- Lymphokines/genetics
- Lymphokines/metabolism
- Mice
- Models, Biological
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Oxindoles
- Paracrine Communication
- Platelet-Derived Growth Factor/pharmacology
- Propionates
- Proto-Oncogene Proteins c-sis
- Pyrroles/pharmacology
- RNA, Messenger/metabolism
- Tumor Cells, Cultured
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factors
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Affiliation(s)
- N Reinmuth
- Department of Cancer Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030-4009, USA
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40
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Yamasaki Y, Miyoshi K, Oda N, Watanabe M, Miyake H, Chan J, Wang X, Sun L, Tang C, McMahon G, Lipson KE. Weekly dosing with the platelet-derived growth factor receptor tyrosine kinase inhibitor SU9518 significantly inhibits arterial stenosis. Circ Res 2001; 88:630-6. [PMID: 11282898 DOI: 10.1161/01.res.88.6.630] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [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: 11/16/2022]
Abstract
The platelet-derived growth factor (PDGF) ligands and their receptors have been implicated as critical regulators of the formation of arterial lesions after tissue injury. SU9518 (3[5-(5-bromo-2-oxo-1,2-dihydroindol-3-ylidenemethyl)-2,4-dimethyl-1H-pyrrol-3-yl]propionic acid) is a novel synthetic indolinone that potently and selectively inhibits the cellular PDGF receptor kinase and PDGF receptor-induced cell proliferation. Inhibition of PDGF receptor phosphorylation in cell-based assays occurs within 5 minutes after drug exposure and persists for >6 hours after drug removal. The pharmacokinetics indicate plasma levels that exceeded the effective concentration required to inhibit the PDGF receptor in cells for up to 8 hours or 7 days after a single oral or subcutaneous administration, respectively. In the rat balloon arterial injury-induced stenosis model, once-daily oral or once-weekly subcutaneous administration of SU9518 reduced intimal thickening of the carotid artery (ratio of neointimal to medial area, 1.94+/-0.38 versus 1.03+/-0.29 [P<0.01] 2.21+/-0.32 versus 1.34+/-0.45 [P<0.01], respectively). These studies provide the rationale to evaluate PDGF receptor tyrosine kinase inhibitors, including inhibitors related to the indolinone, SU9518, for the treatment of arterial restenosis.
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Affiliation(s)
- Y Yamasaki
- Taiho Pharmaceutical Co, Ltd, Hanno Research Center, Saitama, Japan
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41
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Geng L, Donnelly E, McMahon G, Lin PC, Sierra-Rivera E, Oshinka H, Hallahan DE. Inhibition of vascular endothelial growth factor receptor signaling leads to reversal of tumor resistance to radiotherapy. Cancer Res 2001; 61:2413-9. [PMID: 11289107] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Certain refractory neoplasms, such as glioblastoma multiforme (GBM) and melanoma, demonstrate a resistant tumor phenotype in vivo. We observed that these refractory tumor models (GBM and melanoma) contain blood vessels that are relatively resistant to radiotherapy. To determine whether the vascular endothelial growth factor receptor-2 (Flk-1/KDR) may be a therapeutic target to improve the effects of radiotherapy, we used the soluble extracellular component of Flk-1 (ExFlk), which blocks vascular endothelial growth factor binding to Flk-1 receptor expressed on the tumor endothelium. Both sFlk-1 and the Flk-1-specifc inhibitor SU5416 eliminated the resistance phenotype in GBM and melanoma microvasculature as determined by both the vascular window and Doppler blood flow methods. Human microendothelial cells and human umbilical vein endothelial cells showed minimal radiation-induced apoptosis. The Flk-1 antagonists sFlk-1 and SU5416 reverted these cell models to apoptosis-prone phenotype. Flk-1 antagonists also reverted GBM and melanoma tumor models to radiation-sensitive phenotype after treatment with 3 Gy. These findings demonstrate that the tumor microenvironment including the survival of tumor-associated endothelial cells contributes to tumor blood vessel resistance to therapy.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Animals
- Cell Survival/drug effects
- Cell Survival/physiology
- Cell Survival/radiation effects
- Dose-Response Relationship, Radiation
- Endothelial Growth Factors/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/radiation effects
- Enzyme Inhibitors/pharmacology
- Glioblastoma/blood supply
- Glioblastoma/radiotherapy
- Indoles/pharmacology
- Lymphokines/metabolism
- Melanoma, Experimental/blood supply
- Melanoma, Experimental/radiotherapy
- Mice
- Mice, Inbred C57BL
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/radiotherapy
- Pyrroles/pharmacology
- Radiation Tolerance/drug effects
- Radiation Tolerance/physiology
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor Protein-Tyrosine Kinases/pharmacology
- Receptor Protein-Tyrosine Kinases/physiology
- Receptors, Growth Factor/antagonists & inhibitors
- Receptors, Growth Factor/metabolism
- Receptors, Growth Factor/physiology
- Receptors, Vascular Endothelial Growth Factor
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factors
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Affiliation(s)
- L Geng
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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42
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Shaheen RM, Tseng WW, Davis DW, Liu W, Reinmuth N, Vellagas R, Wieczorek AA, Ogura Y, McConkey DJ, Drazan KE, Bucana CD, McMahon G, Ellis LM. Tyrosine kinase inhibition of multiple angiogenic growth factor receptors improves survival in mice bearing colon cancer liver metastases by inhibition of endothelial cell survival mechanisms. Cancer Res 2001; 61:1464-8. [PMID: 11245452] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Redundant mechanisms mediate colon cancer angiogenesis. Targeting multiple angiogenic factors simultaneously may improve survival of mice with colon cancer metastases. BALB/c mice underwent splenic injection with CT-26 colon cancer cells to generate liver metastases and received administration of either vehicle alone or a tyrosine kinase inhibitor for vascular endothelial growth factor, basic fibroblast growth factor, and platelet-derived growth factor receptors (SU6668). Mice were sacrificed when they became moribund as determined by a blinded observer. In a parallel experiment, groups of mice were sacrificed at earlier time points to better define the kinetics of the effect of SU6668 on angiogenic parameters over time. SU6668 increased median survival by 58% (P < 0.001) and led to a progressive increase in tumor cell and endothelial cell apoptosis that increased over time. In addition, pericyte vessel coverage and tumor vascularity were significantly decreased in mice treated with SU6668. Based on current knowledge of endothelial cell survival, these data suggest that SU6668 may prevent tumor endothelial cell survival directly (vascular endothelial growth factor) and indirectly (pericyte coverage) by affecting endothelial cell survival mechanisms.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Animals
- Apoptosis/drug effects
- Cell Division/drug effects
- Cell Survival
- Colonic Neoplasms/blood supply
- Colonic Neoplasms/drug therapy
- Colonic Neoplasms/pathology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Indoles/pharmacology
- Liver Neoplasms, Experimental/blood supply
- Liver Neoplasms, Experimental/drug therapy
- Liver Neoplasms, Experimental/secondary
- Mice
- Mice, Inbred BALB C
- Neovascularization, Pathologic/drug therapy
- Oxindoles
- Propionates
- Pyrroles/pharmacology
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptors, Fibroblast Growth Factor/antagonists & inhibitors
- Receptors, Growth Factor/antagonists & inhibitors
- Receptors, Platelet-Derived Growth Factor/antagonists & inhibitors
- Receptors, Vascular Endothelial Growth Factor
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Affiliation(s)
- R M Shaheen
- Department of Surgical Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA
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43
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Dührsen U, Martinez T, Vohwinkel G, Ergün S, Sun L, McMahon G, Dürig J, Hossfeld DK, Fiedler W. Effects of vascular endothelial and platelet-derived growth factor receptor inhibitors on long-term cultures from normal human bone marrow. Growth Factors 2001; 19:1-17. [PMID: 11678206 DOI: 10.3109/08977190109001072] [Citation(s) in RCA: 15] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Endothelial cells and fibroblasts are important constituents of the haemopoietic microenvironment. Growth and function of these cells are controlled by a variety of cytokines, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). We analysed the effects of novel tyrosine kinase inhibitors targeting the VEGF and PDGF receptors (compounds SU5614 and SU5768) on the performance of long-term cultures from normal human bone marrow. In developing cultures, the inhibitors induced a dose-dependent reduction in stromal fibroblasts, macrophages and endothelial cells with a concomitant decrease in blood cell production and an increase in fat cells. For SU5614, the concentration inhibiting stroma formation by 50% (IC50) was 123nM, and the IC50 for haemopoietic colony forming cell output was 186 nM. For SU5768, the respective values were 871 nM and 331 nM. Changes in stroma composition and inhibition of haemopoietic cell production were also demonstrable after delayed addition of the inhibitors to established cultures. By contrast, haemopoietic colony formation in clonogenic agar cultures was unimpaired (IC50 not reached at 100 microM). Immunofluorescence studies and time course analyses suggested that the primary effect of the inhibitors was interference with the proliferation and function of fibroblasts and endothelial cells which in turn resulted in decreased haemopoiesis and increased adipogenesis. This was associated with decreased levels in conditioned media of granulocyte-macrophage colony-stimulating factor, interleukin-6 and leptin. VEGF and PDGF may play a hitherto underestimated role in the control of blood cell formation. VEGF/PDGF receptor inhibitors may have therapeutic potential in stroma diseases such as myelofibrosis. Since they weaken the stimulatory signals provided by the microenvironment, they may also be of value in the treatment of leukaemia and other neoplastic bone marrow diseases.
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Affiliation(s)
- U Dührsen
- Zentrum für Innere Medizin, Abteilung für Hämatologie, Universitätsklinikum Essen, Germany.
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Laird AD, Vajkoczy P, Shawver LK, Thurnher A, Liang C, Mohammadi M, Schlessinger J, Ullrich A, Hubbard SR, Blake RA, Fong TA, Strawn LM, Sun L, Tang C, Hawtin R, Tang F, Shenoy N, Hirth KP, McMahon G. SU6668 is a potent antiangiogenic and antitumor agent that induces regression of established tumors. Cancer Res 2000; 60:4152-60. [PMID: 10945623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Vascular endothelial growth factor, fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) and their cognate receptor tyrosine kinases are strongly implicated in angiogenesis associated with solid tumors. Using rational drug design coupled with traditional screening technologies, we have discovered SU6668, a novel inhibitor of these receptors. Biochemical kinetic studies using isolated Flk-1, FGF receptor 1, and PDGF receptor beta kinases revealed that SU6668 has competitive inhibitory properties with respect to ATP. Cocrystallographic studies of SU6668 in the catalytic domain of FGF receptor 1 substantiated the adenine mimetic properties of its oxindole core. Molecular modeling of SU6668 in the ATP binding pockets of the FIk-1/KDR and PDGF receptor kinases provided insight to explain the relative potency and selectivity of SU6668 for these receptors. In cellular systems, SU6668 inhibited receptor tyrosine phosphorylation and mitogenesis after stimulation of cells by appropriate ligands. Oral or i.p. administration of SU6668 in athymic mice resulted in significant growth inhibition of a diverse panel of human tumor xenografts of glioma, melanoma, lung, colon, ovarian, and epidermoid origin. Furthermore, intravital multifluorescence videomicroscopy of C6 glioma xenografts in the dorsal skinfold chamber model revealed that SU6668 treatment suppressed tumor angiogenesis. Finally, SU6668 treatment induced striking regression of large established human tumor xenografts. Investigations of SU6668 activity in cancer patients are ongoing in Phase I clinical trials.
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MESH Headings
- 3T3 Cells
- Angiogenesis Inhibitors/chemistry
- Angiogenesis Inhibitors/pharmacology
- Animals
- Antineoplastic Agents/chemistry
- Antineoplastic Agents/pharmacology
- Cell Division/drug effects
- Crystallography, X-Ray
- Dose-Response Relationship, Drug
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/enzymology
- Enzyme Inhibitors/chemistry
- Enzyme Inhibitors/pharmacology
- Female
- Humans
- Indoles/chemistry
- Indoles/pharmacology
- Kinetics
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Models, Molecular
- Neoplasm Transplantation
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/drug therapy
- Neovascularization, Pathologic/drug therapy
- Oxindoles
- Propionates
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Pyrroles/chemistry
- Pyrroles/pharmacology
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor, Platelet-Derived Growth Factor beta/antagonists & inhibitors
- Receptors, Fibroblast Growth Factor/antagonists & inhibitors
- Receptors, Growth Factor/antagonists & inhibitors
- Receptors, Mitogen/antagonists & inhibitors
- Receptors, Vascular Endothelial Growth Factor
- Transplantation, Heterologous
- Tumor Cells, Cultured
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Affiliation(s)
- A D Laird
- SUGEN, Inc., San Francisco, California 94080, USA
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45
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Abstract
Protein tyrosine kinases have emerged as crucial targets for therapeutic intervention in cancer. More recently, growth factor ligands and their respective receptor tyrosine kinases (RTKs) have been shown to be required for tumor cell growth. This latter aspect includes tumor angiogenesis where the growth of tumors leads to compensatory effects on host cells in the tumor microenvironment leading to the growth of microvessels. The purpose of this review is to focus on synthetic chemical approaches to block RTKs associated with tumor angiogenesis as a means to limit the growth and spread of human tumors.
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Affiliation(s)
- L Sun
- SUGEN, 230 E Grand Avenue, South San Francisco, CA 94080, USA
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Sun L, Tran N, Liang C, Hubbard S, Tang F, Lipson K, Schreck R, Zhou Y, McMahon G, Tang C. Identification of substituted 3-[(4,5,6, 7-tetrahydro-1H-indol-2-yl)methylene]-1,3-dihydroindol-2-ones as growth factor receptor inhibitors for VEGF-R2 (Flk-1/KDR), FGF-R1, and PDGF-Rbeta tyrosine kinases. J Med Chem 2000; 43:2655-63. [PMID: 10893303 DOI: 10.1021/jm9906116] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [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: 11/28/2022]
Abstract
A series of new 3-substituted indolin-2-ones containing a tetrahydroindole moiety was developed as specific inhibitors of receptor tyrosine kinases associated with VEGF-R, FGF-R, and PDGF-R growth factor receptors. These compounds were evaluated for their inhibitory properties toward VEGF-R2 (Flk-1/KDR), FGF-R1, PDGF-Rbeta, p60(c)()(-)()(Src)(), and EGF-R tyrosine kinases and their ability to inhibit growth factor-dependent cell proliferation. Structure-activity relationships of this new pharmacophore have been determined at the level of kinase inhibition. Compounds containing a propionic acid moiety at the C-3' position of the tetrahydroindole ring represented the most potent indolin-2-ones to inactivate the VEGF, FGF, and PDGF receptor kinases. The inhibitory activities of 9d against VEGF-R2 (Flk-1), 9h against FGF-R1, and 9b against PDGF-Rbeta were 4, 80, and 4 nM, respectively. However, all of these compounds were inactive when tested against the EGF-R tyrosine kinase. Compounds 9a and 9b represented the most potent inhibitors of these classes to inhibit both biochemical kinase and growth factor-dependent cell proliferation for these three targets. In addition, compound 9a was cocrystallized with the catalytic domain of FGF-R1 providing evidence to explain the structure-activity relationship results. This study has provided evidence to support the potential of these new tyrosine kinase inhibitors for the treatment of angiogenesis and other growth factor-related diseases including human cancers.
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Affiliation(s)
- L Sun
- SUGEN, Inc., 230 East Grand Avenue, South San Francisco, California 94080-4811, USA.
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47
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Abstract
Following amputation of a urodele limb or teleost fin, the formation of a blastema is a crucial step in facilitating subsequent regeneration. Using the zebrafish caudal fin regeneration model, we have examined the hypothesis that fibroblast growth factors (Fgfs) initiate blastema formation from fin mesenchyme. We find that fibroblast growth factor receptor 1 (fgfr1) is expressed in mesenchymal cells underlying the wound epidermis during blastema formation and in distal blastemal tissue during regenerative outgrowth. fgfr1 transcripts colocalize with those of msxb and msxc, putative markers for undifferentiated, proliferating cells. A zebrafish Fgf member, designated wfgf, is expressed in the regeneration epidermis during outgrowth. Furthermore, we show that a specific inhibitor of Fgfr1 applied immediately following fin amputation blocks blastema formation, without obvious effects on wound healing. This inhibitor blocks the proliferation of blastemal cells and the onset of msx gene transcription. Inhibition of Fgf signaling during ongoing fin regeneration prevents further outgrowth while downregulating the established expression of blastemal msx genes and epidermal sonic hedgehog. Our findings indicate that zebrafish fin blastema formation and regenerative outgrowth require Fgf signaling.
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Affiliation(s)
- K D Poss
- Howard Hughes Medical Institute, Eccles Institute of Human Genetics, University of Utah Health Sciences Center, 15N 2030E, Salt Lake City, Utah, 84112, USA
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48
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Makarenkova HP, Ito M, Govindarajan V, Faber SC, Sun L, McMahon G, Overbeek PA, Lang RA. FGF10 is an inducer and Pax6 a competence factor for lacrimal gland development. Development 2000; 127:2563-72. [PMID: 10821755 DOI: 10.1242/dev.127.12.2563] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.8] [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: 11/20/2022]
Abstract
We investigated the mechanism of tissue induction and specification using the lacrimal gland as a model system. This structure begins its morphogenesis as a bud-like outgrowth of the conjunctival epithelium and ultimately forms a branched structure with secretory function. Using a reporter transgene as a specific marker for gland epithelium, we show that the transcription factor Pax6 is required for normal development of the gland and is probably an important competence factor. In investigating the cell-cell signaling required, we show that fibroblast growth factor (FGF) 10 is sufficient to stimulate ectopic lacrimal bud formation in ocular explants. Expression of FGF10 in the mesenchyme adjacent to the presumptive lacrimal bud and absence of lacrimal gland development in FGF10-null mice strongly suggest that it is an endogenous inducer. This was supported by the observation that inhibition of signaling by a receptor for FGF10 (receptor 2 IIIb) suppressed development of the endogenous lacrimal bud. In explants of mesenchyme-free gland epithelium, FGF10 stimulated growth but not branching morphogenesis. This suggested that its role in induction is to stimulate proliferation and, in turn, that FGF10 combines with other factors to provide the instructive signals required for lacrimal gland development.
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Affiliation(s)
- H P Makarenkova
- Skirball Institute for Biomolecular Medicine, Developmental Genetics Program, Cell Biology and Pathology Departments, New York University Medical Center, New York, NY 10016, USA
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49
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Abstract
The growth of human tumors and development of metastases depend on the de novo formation of blood vessels. The formation of new blood vessels is tightly regulated by specific growth factors that target receptor tyrosine kinases (RTKs). Vascular endothelial growth factor (VEGF) and the Flk-1/KDR RTK have been implicated as the key endothelial cell-specific factor signaling pathway required for pathological angiogenesis, including tumor neovascularization. Inhibition of the VEGF tyrosine kinase signaling pathway blocks new blood vessel formation in growing tumors, leading to stasis or regression of tumor growth. Advances in understanding the biology of angiogenesis have led to the development of several therapeutic modalities for the inhibition of the VEGF tyrosine kinase signaling pathway. A number of these modalities are under investigation in clinical studies to evaluate their potential to treat human cancers.
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Affiliation(s)
- G McMahon
- SUGEN, Inc., South San Francisco, California 94080, USA.
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50
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Abstract
Some forms of mastocytosis are caused by c-kit mutations which cause constitutive activation of kit kinase. Compounds that inhibit kit kinase, such as indolinones, are therefore attractive as potential therapeutic agents. A hierarchy exists in the ability of compounds to inhibit kit kinase effectively. Some compounds can inhibit ligand-induced activation of wild-type receptor but are ineffective against constitutively activated mutants. Other compounds can inhibit ligand-induced activation of wild-type kit and ligand-independent activation by juxtamembrane domain mutations but not activation by activation loop mutations. Still others effectively inhibit wild-type kit and constitutively activated kit bearing either juxtamembrane or kinase domain mutations and kill the neoplastic mast cells expressing these mutants. No therapy currently exists that specifically targets a cause of mastocytosis, but there are good reasons to believe that kit kinase inhibitors may fulfill that role someday.
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Affiliation(s)
- B J Longley
- Department of Dermatology, College of Physicians and Surgeons, Columbia University, New York, New York, USA.
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