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Search Results: 1 - 10 of 459859 matches for " Philip M. W. Bath "
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The Cog-4 Subset of the National Institutes of Health Stroke Scale as a Measure of Cognition: Relationship with Baseline Factors and Functional Outcome after Stroke Using Data from the Virtual International Stroke Trials Archive
Sandeep Ankolekar,Cheryl Renton,Nikola Sprigg,Philip M. W. Bath
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/562506
Abstract:
The Cog-4 Subset of the National Institutes of Health Stroke Scale as a Measure of Cognition: Relationship with Baseline Factors and Functional Outcome after Stroke Using Data from the Virtual International Stroke Trials Archive
Sandeep Ankolekar,Cheryl Renton,Nikola Sprigg,Philip M. W. Bath
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/562506
Abstract: Background. Assessing poststroke cognitive impairment is complex. A subscale of the NIHSS, the Cog-4, has been proposed as a quick test of “cognitive impairment.” but a study of its properties in a larger dataset is lacking. Methods. Data from 9,147 patients with acute stroke from the VISTA archive was used to generate Cog-4 scores. The statistical properties of Cog-4, its relationship with baseline clinical characteristics, and other functional outcome measures at day 90 were assessed. Results. Mean age of patients was 69.2 years and 45.8%, were females. Day-90 Cog-4 was highly positively skewed (skewness 0.926). Patients with left hemispheric stroke had higher day-90 Cog-4 score ( ). Age, stroke severity, and previous stroke were significant predictors of Cog-4. Cog-4 was significantly correlated with dependency (modified Rankin Scale, ), and disability (Barthel Index, ). Conclusions. The Cog-4 scale at day 90 cannot be considered a useful test of cognition since it only superficially measures cognition. It is heavily dependent on the side of stroke, is inevitably associated with functional outcome (being a subset of the NIHSS), and suffers from a profound “floor” effect. Specific and validated measures are more appropriate for the assessment of poststroke cognition than Cog-4. 1. Introduction Poststroke cognitive impairment (PSCI) is an important but poorly studied consequence of stroke and is a significant risk factor for developing frank dementia [1, 2]. PSCI diagnosed in the first few months after stroke may progress to dementia, remain stable, or improve over the following months to years [3, 4]. It is important to understand factors that are responsible for the development of PSCI, and study the impact of PSCI on other functional outcomes to develop preventative and management strategies. However, research on PSCI has been hindered, partly by the relative lack of relevant measures of cognition and standardised diagnostic criteria to identify this condition, and partly by the lack of use of these in acute stroke and secondary prevention trials [5]. It is well established that the neurocognitive profile of PSCI, poststroke dementia, and vascular dementia differs from Alzheimer’s disease, the most common type of dementia [6–8], but their frequent coexistence can cause diagnostic challenges. Vascular dementia typically damages executive function and yet standard cognitive screening tests such as the Mini-Mental State Examination (MMSE) lack a significant measure of executive component [9, 10]. A number of newer cognitive screening tests, including
Publication Bias in Reports of Animal Stroke Studies Leads to Major Overstatement of Efficacy
Emily S. Sena,H. Bart van der Worp,Philip M. W. Bath,David W. Howells,Malcolm R. Macleod
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000344
Abstract: The consolidation of scientific knowledge proceeds through the interpretation and then distillation of data presented in research reports, first in review articles and then in textbooks and undergraduate courses, until truths become accepted as such both amongst “experts” and in the public understanding. Where data are collected but remain unpublished, they cannot contribute to this distillation of knowledge. If these unpublished data differ substantially from published work, conclusions may not reflect adequately the underlying biological effects being described. The existence and any impact of such “publication bias” in the laboratory sciences have not been described. Using the CAMARADES (Collaborative Approach to Meta-analysis and Review of Animal Data in Experimental Studies) database we identified 16 systematic reviews of interventions tested in animal studies of acute ischaemic stroke involving 525 unique publications. Only ten publications (2%) reported no significant effects on infarct volume and only six (1.2%) did not report at least one significant finding. Egger regression and trim-and-fill analysis suggested that publication bias was highly prevalent (present in the literature for 16 and ten interventions, respectively) in animal studies modelling stroke. Trim-and-fill analysis suggested that publication bias might account for around one-third of the efficacy reported in systematic reviews, with reported efficacy falling from 31.3% to 23.8% after adjustment for publication bias. We estimate that a further 214 experiments (in addition to the 1,359 identified through rigorous systematic review; non publication rate 14%) have been conducted but not reported. It is probable that publication bias has an important impact in other animal disease models, and more broadly in the life sciences.
Publication Bias in Reports of Animal Stroke Studies Leads to Major Overstatement of Efficacy
Emily S. Sena,H. Bart van der Worp,Philip M. W. Bath,David W. Howells,Malcolm R. Macleod
PLOS Biology , 2010, DOI: 10.1371/journal.pbio.1000344
Abstract: The consolidation of scientific knowledge proceeds through the interpretation and then distillation of data presented in research reports, first in review articles and then in textbooks and undergraduate courses, until truths become accepted as such both amongst “experts” and in the public understanding. Where data are collected but remain unpublished, they cannot contribute to this distillation of knowledge. If these unpublished data differ substantially from published work, conclusions may not reflect adequately the underlying biological effects being described. The existence and any impact of such “publication bias” in the laboratory sciences have not been described. Using the CAMARADES (Collaborative Approach to Meta-analysis and Review of Animal Data in Experimental Studies) database we identified 16 systematic reviews of interventions tested in animal studies of acute ischaemic stroke involving 525 unique publications. Only ten publications (2%) reported no significant effects on infarct volume and only six (1.2%) did not report at least one significant finding. Egger regression and trim-and-fill analysis suggested that publication bias was highly prevalent (present in the literature for 16 and ten interventions, respectively) in animal studies modelling stroke. Trim-and-fill analysis suggested that publication bias might account for around one-third of the efficacy reported in systematic reviews, with reported efficacy falling from 31.3% to 23.8% after adjustment for publication bias. We estimate that a further 214 experiments (in addition to the 1,359 identified through rigorous systematic review; non publication rate 14%) have been conducted but not reported. It is probable that publication bias has an important impact in other animal disease models, and more broadly in the life sciences.
A Randomised Controlled Trial of Triple Antiplatelet Therapy (Aspirin, Clopidogrel and Dipyridamole) in the Secondary Prevention of Stroke: Safety, Tolerability and Feasibility
Nikola Sprigg, Laura J. Gray, Tim England, Mark R. Willmot, Lian Zhao, Gillian M. Sare, Philip M. W. Bath
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002852
Abstract: Background Aspirin, dipyridamole and clopidogrel are effective in secondary vascular prevention. Combination therapy with three antiplatelet agents might maximise the benefit of antiplatelet treatment in the secondary prevention of ischaemic stroke. Methodology/Principal Findings A randomised, parallel group, observer-blinded phase II trial compared the combination of aspirin, clopidogrel and dipyridamole with aspirin alone. Adult patients with ischaemic stroke or transient ischaemic attack (TIA) within 5 years were included. The primary outcome was tolerability to treatment assessed as the number of patients completing randomised treatment. Recruitment was halted prematurely after publication of the ESPRIT trial (which confirmed that combined aspirin and dipyridamole is more effective than aspirin alone). 17 patients were enrolled: male 12 (71%), mean age 62 (SD 13) years, lacunar stroke syndrome 12 (71%), median stroke/TIA onset to randomisation 8 months. Treatment was discontinued in 4 of 9 (44%) patients receiving triple therapy vs. none of 8 taking aspirin (p = 0.08). One recurrent stroke occurred in a patient in the triple group who was noncompliant of all antiplatelet medications. The number of patients with adverse events and bleeding complications, and their severity, were significantly greater in the triple therapy group (p<0.01). Conclusions/Significance Long term triple antiplatelet therapy was asociated with a significant increase in adverse events and bleeding rates, and their severity, and a trend to increased discontinuations. However, the patients had a low risk of recurrence and future trials should focus on short term therapy in high risk patients characterised by a very recent event or failure of dual antiplatelet therapy. Trial Registration Controlled-Trials.com ISRCTN83673558
Effect of Telmisartan on Cerebral and Systemic Haemodynamics in Patients with Recent Ischaemic Stroke: A Randomised Controlled Trial
Gillian M. Sare,Andrew Ghadami,Sandeep Ankolekar,Timothy England,Fiona Hammonds,Margaret Adrian,Judith Clarke,Lynn Stokes,Dorothee Auer,Philip M. W. Bath
ISRN Stroke , 2013, DOI: 10.1155/2013/587954
Abstract: High blood pressure (BP) is common in acute stroke and is independently associated with a poor outcome. Lowering BP might improve outcome if cerebral blood flow (CBF) is unaffected in the presence of dysfunctional autoregulation. We investigated the effect of telmisartan on systemic and cerebral haemodynamics in patients with recent stroke. Patients with ischaemic stroke (<5 days) were randomised to 90 days of telmisartan (80?mg) or placebo. CBF (primary outcome) was measured using xenon CT at baseline and 4 hours. BP and transcranial doppler (TCD) were performed at baseline, 4 hours after-treatment, and on days 4, 7, and 90. Cerebral perfusion pressure and zero filling pressure (ZFP) were calculated. Of a planned 24 patients, 17 were recruited. Telmisartan significantly accentuated the fall in systolic and diastolic BP over 90 days (treatment-time interaction , resp.) but did not alter BP at 4 hours after treatment (171/99 versus 167/87?mmHg), CBF, or CBF velocity. ZFP was significantly lower in the treatment group . Impairment at 7 days and dependency at 90 days did not differ between the groups. In this underpowered study, telmisartan did not significantly alter BP or CBF after the first dose. Telmisartan reduced BP over the subsequent 90 days and significantly lowered ZFP. This trial is registered with ISRCTN 41456162. 1. Introduction High blood pressure (BP) is common and associated independently with a poor outcome in patients with acute stroke [1–3]. However, there are no definitive data guiding the management of high BP. Individual small studies of BP modifying agents in acute stroke have indicated potential efficacy [4–6] or harm [7, 8]. A metaregression analysis of these and other trials suggested that systolic BP reductions in the order of 10–15?mmHg reduction were associated with a trend to reduced death at the end of trial, although the confidence intervals were wide and compatible with benefit or harm [9]; more extreme BP lowering or any form of BP elevation was associated with harm [3, 9]. The recently published large SCAST trial showed that candesartan only modestly lowered BP and had no beneficial effect on dependency or further vascular events [10]. Further large trials of BP lowering in acute stroke are underway including ENOS and INTERACT-2 [11]. However, since antihypertensive agents vary in their mode of action and their potential effects on cerebral blood flow, trials of individual agents may not be generalisable across all antihypertensive agents. Cerebral autoregulation is dysfunctional in acute stroke [12] and BP lowering could
Determining the Feasibility of Ambulance-Based Randomised Controlled Trials in Patients with Ultra-Acute Stroke: Study Protocol for the “Rapid Intervention with GTN in Hypertensive Stroke Trial” (RIGHT, ISRCTN66434824)
Sandeep Ankolekar,Gillian Sare,Chamila Geeganage,Michael Fuller,Lynn Stokes,Nikola Sprigg,Ruth Parry,A. Niroshan Siriwardena,Philip M. W. Bath
Stroke Research and Treatment , 2012, DOI: 10.1155/2012/385753
Abstract: Background. Time from acute stroke to enrolment in clinical trials needs to be reduced to improve the chances of finding effective treatments. No completed randomised controlled trials of ambulance-based treatment for acute stroke have been reported in the UK, and the practicalities of recruiting, consenting, and treating patients are unknown. Methods. RIGHT is an ambulance based, single-blind, randomised controlled trial with blinded-outcome assessment. The trial will assess feasibility of using ambulance services to deliver ultra-acute stroke treatments; a secondary aim is to assess the effect of glyceryl trinitrate (GTN) on haemodynamic variables and functional outcomes. Initial consent, randomisation, and treatment are performed by paramedics prior to hospitalisation. Patients with ultra-acute stroke (≤4 hours of onset) are randomised to transdermal GTN (5?mg/24 hours) or gauze dressing daily for 7 days. The primary outcome is systolic blood pressure at 2 hours. Secondary outcomes include feasibility, haemodynamics, dependency, and other functional outcomes. A nested qualitative study is included. Trial Status. The trial has all relevant ethics and regulatory approvals and recruitment started on February 15, 2010. The trial stopped recruitment in December 2011 after 41 patients were recruited. Trial Registration. The trial registration number is ISRCTN66434824 and EudraCT number is 2007-004766-40. 1. Background Finding acute interventions which reduce early brain damage and improve outcome after acute stroke is of major importance and has proved challenging. Irreversible brain damage starts in the first minutes to hours after a stroke [1] and acute stroke treatments can be highly time dependent; outcomes after stroke thrombolysis are better when treatment is given early [2]. Ambulance administration of emergency treatment is standard in acute medical emergencies such as acute myocardial infarction and asthma; thrombolysis for MI was given 45 minutes earlier if administered in an ambulance than at hospital [3]. Treatments for acute ischaemic stroke (AIS) are not routinely administered prior to hospital since current therapies reduce haemostasis (e.g., aspirin and alteplase) and need neuroimaging to exclude primary intracerebral haemorrhage (PICH). However, other potential treatments for acute stroke such as neuroprotection and management of physiological disturbances (e.g., high blood pressure [BP], hyperglycaemia and pyrexia) do not necessarily need prior neuroimaging and could be delivered before hospitalisation. As benefits of such interventions
Teleseismic magnitude relations
M. BATH
Annals of Geophysics , 1977, DOI: 10.4401/ag-4825
Abstract: RIASSUNTO - Le raccomandazioni fatte a Zurigo nel 1967, sulla determinazione della magnitudo, hanno avuto diverse notevoli applicazioni usando valide serie complete di valori determinati dalla magnitudo, cominciando anzitutto a servirsi di quelli raccolti dal bollettino sismico di Uppsala. In questo modo sono state correlate le magnitudo (in) delle onde spaziali e quelle (M) delle onde superficiali, le une rispetto alle altre, per 12 diverse regioni sismiche diffuse e conosciute in tutto il mondo. Si sono trovate le correzioni di M relative a tutte le profondità focali. Sono state sviluppate formule che permettono il calcolo di M anche dalla componente verticale dei sismografi a lungo periodo. Sono state messe a confronto le magnitudo delle onde spaziali ottenute su registrazioni ad alta e bassa banda di sismografi a breve periodo e ne sono state dedotte le relazioni corrispondenti. Sono state fatte applicazioni sia ad esplosioni nucleari sotterranee sia a terremoti. Vengono inoltre valutate le possibilità di discriminare, servendosi della magnitudo, le esplosioni dai terremoti, come pure - sempre dalla magnitudo - di valutare quanto esplosivo sia stato usato. Per quanto riguarda i terremoti, vengono studiate le relazioni fra le magnitudo delle scosse principali e quelle delle repliche più forti. Per determinazioni più omogenee della magnitudo si suggerisce di istituire una rete mondiale di stazioni che possa fornire il necessario sistema d'informazioni.
SOME CONSEQUENCE OF THE EXISTENCE OF LOW-VELOCITY LAYERS
M. BATH
Annals of Geophysics , 1956, DOI: 10.4401/ag-5615
Abstract: The velocities of elastic waves (P and S) generally increase with depth in the earth. If at some depth this increase is replaced by a decrease over an interval of depth, again followed by an increase at some greater depth, we have, what we cali a low-velocity layer, provided the numerical value of the velocity decrease with depth in at least a part of the layer surpasses the criticai value v/r (v = velocity, r = radius; see Gutenberg, 1954 b, and Bullen, 1954, pp. 87-89). The most marked low-velocity layer (for P waves) exists on the inner side of the outer core. This low-velocity layer has already been recognized by ali seismologists long ago. If a low-velocity layer exists also at the boundary of the inner core, is not yet certain. According to Jeffreys there is one, whereas Gutenberg does not find suffìcient observational support for it.
The pathogenesis of primary pouchitis following ileal pouch-anal anastomosis: a review of current hypotheses  [PDF]
Sally Bath, Christian P. Selinger, Rupert W.L. Leong
Open Journal of Gastroenterology (OJGas) , 2011, DOI: 10.4236/ojgas.2011.12002
Abstract: Primary pouchitis is a common complication of ileal pouch-anal anastomosis following proctocolectomy in patients treated for ulcerative colitis (UC), but is un-usual for those treated for familial adenomatous polyposis (FAP). While a number of theories as to the pathogenesis of this inflammatory condition have been proposed, no single one has been wholly satis-factory. Much research has been devoted to investi-gating a link between the pathogenic factors involved in UC, but not FAP, and those underlying pouchitis. The contribution of sulfate-producing bacteria has also been explored. The role of other intraluminal factors, such as short chain fatty acids and unconju-gated bile salts, has also been investigated. A unifying theory of a multi-step process might explain the pathogenesis of pouchitis, but further research is re-quired to proof causation. It is likely that pouchitis develops as a result of a combination of genetic, im-munological, microbial and metabolic factors. Future insight into the causes of pouchitis may eventually allow for the development of more effective treat-ments.
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