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result(s) for
"Tasker, R. R."
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Epidemiology of traumatic brain injury in children receiving intensive care in the UK
by
Parslow, R C
,
Morris, K P
,
Tasker, R C
in
Accidents, Traffic - statistics & numerical data
,
Adolescent
,
Age groups
2005
Aims: To describe the epidemiology of children with traumatic brain injury (TBI) admitted to paediatric intensive care units (PICUs) in the UK. Methods: Prospective collection of clinical and demographic information from paediatric and adult intensive care units in the UK and Eire between February 2001 and August 2003. Results: The UK prevalence rate for children (0–14 years) admitted to intensive care with TBI between February 2001 and August 2003 was 5.6 per 100 000 population per year (95% Poisson exact confidence intervals 5.17 to 6.05). Children admitted to PICUs with TBI were more deprived than the population as a whole (mean Townsend score for TBI admissions 1.19 v 0). The commonest mechanism of injury was a pedestrian accident (36%), most often occurring in children over 10. There was a significant summer peak in admissions in children under 10 years. Time of injury peaked in the late afternoon and early evening, a pattern that remained constant across the days of the week. Injuries involving motor vehicles have the highest mortality rates (23% of vehicle occupants, 12% of pedestrians) compared with cyclists (8%) and falls (3%). In two thirds of admissions (65%) TBI was an isolated injury. Conclusions: TBI in children requiring intensive care is more common in those from poorer backgrounds who have been involved in accidents as pedestrians. The summer peak in injury occurrence for 0–10 year olds and late afternoon timing give clear targets for community based injury prevention.
Journal Article
Effects of elevated temperature, reduced hydroperiod, and invasive bullfrog larvae on pacific chorus frog larvae
2022
Climate change and invasive species threaten many ecosystems, including surface freshwater systems. Increasing temperatures and reduced hydroperiod due to climate change may promote the persistence of invasive species and facilitate new invasions due to potentially higher tolerance to environmental stress in successful invaders. Amphibians demonstrate high levels of plasticity in life history characteristics, particularly those species which inhabit both ephemeral and permanent water bodies. We tested the influence of two projected effects of climate change (increased temperature and reduced hydroperiod) on Pacific chorus frog ( Pseudacris regilla ) tadpoles alone and in combination with the presence of tadpoles of a wide-spread invasive amphibian, the American bullfrog ( Lithobates catesbeianus ). Specifically, we explored the effects of projected climate change and invasion on survival, growth, mass at stage 42, and development rate of Pacific chorus frogs. Direct and indirect interactions between the invasive tadpole and the native tadpole were controlled via a cage treatment and were included to account for differences in presence of the bullfrog compared to competition for food resources and other direct effects. Overall, bullfrogs had larger negative effects on Pacific chorus frogs than climate conditions. Under future climate conditions, Pacific chorus frogs developed faster and emerged heavier. Pacific chorus frog tadpoles developing in the presence of American bullfrogs, regardless of cage treatment, emerged lighter. When future climate conditions and presence of invasive American bullfrog tadpoles were combined, tadpoles grew less. However, no interaction was detected between climate conditions and bullfrog presence for mass, suggesting that tadpoles allocated energy towards mass rather than length under the combined stress treatment. The maintenance of overall body condition (smaller but heavier metamorphs) when future climate conditions overlap with bullfrog presence suggests that Pacific chorus frogs may be partially compensating for the negative effects of bullfrogs via increased allocation of energy towards mass. Strong plasticity, as demonstrated by Pacific chorus frog larvae in our study, may allow species to match the demands of new environments, including under future climate change.
Journal Article
Emergency management of children with severe sepsis in the United Kingdom: the results of the Paediatric Intensive Care Society sepsis audit
by
Inwald, D P
,
Nadel, S
,
Tasker, R C
in
Administrative Organization
,
Algorithms
,
Attrition (Research Studies)
2009
Objective:To audit current UK practice of the management of severe sepsis in children against the 2002 American College of Critical Care Medicine/Pediatric Advanced Life Support (ACCM-PALS) guideline.Design:Prospective observational study.Setting:17 UK paediatric intensive care units (PICUs) and two UK PICU transport services.Participants:200 children accepted for PICU admission within 12 h of arrival in hospital, whether or not successfully transported to a PICU, with a discharge diagnosis of sepsis or suspected sepsis.Main outcome measures:Medical interventions, physiological and laboratory data to determine the presence or absence of shock, inter-hospital transfer times, predicted mortality (using the Paediatric Index of Mortality, version 2 (PIM2) scoring system) and observed mortality.Results:34/200 (17%) children died following referral. Although children defined as being in shock received significantly more fluid (p<0.001) than those who were not in shock, overall fluid and inotrope management suggested by the 2002 ACCM-PALS guideline was not followed in 62% of shocked children. Binary logistic regression analysis demonstrated that the odds ratio for death, if shock was present at PICU admission, was 3.8 (95% CI 1.4 to 10.2, p = 0.008).Conclusions:The presence of shock at PICU admission is associated with an increased risk of death. Despite clear consensus guidelines for the emergency management of children with severe sepsis and septic shock, most children received inadequate fluid resuscitation and inotropic support in the crucial few hours following presentation.
Journal Article
Prefrontal Ischemia in the Rat Leads to Secondary Damage and Inflammation in Remote Gray and White Matter Regions
by
Weishaupt, Nina
,
Deziel, Robert A.
,
Tasker, R. Andrew
in
Anti-inflammatory agents
,
Axonal degeneration
,
Brain
2016
Secondary damage processes, such as inflammation and oxidative stress, can exacerbate an ischemic lesion and spread to adjacent brain regions. Yet, few studies investigate how regions remote from the infarct could also suffer from degeneration and inflammation in the aftermath of a stroke. To find out to what extent far-remote brain regions are affected after stroke, we used a bilateral endothelin-1-induced prefrontal infarct rat model. Brain regions posterior to the prefrontal cortical infarct were analyzed for ongoing neurodegeneration using FluoroJadeB (FJB) and for neuroinflammation using Iba1 and OX-6 immunohistochemistry 28 days post-stroke. The FJB-positive dorsomedial nucleus of the thalamus (DMN) and retrosplenial area (RSA) of the cortex displayed substantial neuroinflammation. Significant neuronal loss was only observed within the cortex. Significant microglia recruitment and activation in the FJB-positive internal capsule indicates remote white matter pathology. These findings demonstrate that even regions far remote from an infarct are affected predictably based on anatomical connectivity, and that white matter inflammation is an integral part of remote pathology. The delayed nature of this pathology makes it a valid target for preventative treatment, potentially with an extended time window of opportunity for therapeutic intervention using anti-inflammatory agents.
Journal Article
Pain-related neurons in the human cingulate cortex
by
Tasker, R. R.
,
Hutchison, W. D.
,
Lozano, A. M.
in
Animal Genetics and Genomics
,
Behavioral Sciences
,
Biological Techniques
1999
Although it is widely accepted that the cortex participates in pain perception, there is no direct evidence for the existence of cortical neurons that respond to noxious or painful stimuli in humans. Anatomical and neurophysiological studies in animals as well as brain imaging and evoked potential studies in humans suggest that the anterior cingulate cortex (ACC) is an important area for processing sensory information related to pain
1
,
2
,
3
,
4
,
5
,
6
,
7
. We have now identified single neurons in ACC that respond selectively to painful thermal and mechanical stimuli, supporting a role for the ACC in pain perception.
Journal Article
Longitudinal Assessment of Behaviour and Associated Bio-Markers Following Chronic Consumption of β-Sitosterol β-D-Glucoside in Rats: A Putative Model of Parkinson’s Disease
by
Tasker, R Andrew
,
Bigelow, Logan J
,
Ogilvie, Sarah L
in
Alzheimer's disease
,
Amyotrophic lateral sclerosis
,
Basal ganglia
2022
The consumption of cycad (Cycas circinalis) seeds has been linked to the development of Amyotrophic Lateral Sclerosis-Parkinsonism Dementia Complex (ALS-PDC) in humans. ALS-PDC is a clinically variable disease presenting as a combination of symptoms typical of PD and/or ALS. Chronic consumption of β-sitosterol β-D-glucoside (BSSG), a component of the cycad seed, by rats (Rattus norvegicus) has been previously reported to initiate a progressive pathology that develops over several months and manifests as behavioural and histopathological changes that resemble characteristic features of Parkinson’s disease. As part of an independent multi-site validation study, we have tried to replicate and further characterize the BSSG model with a focus on motor function, and associated immunohistochemical markers. Beginning at 3 months of age, male CD® (Sprague Dawley) rats (N=80) were dosed orally with either a flour pellet or a flour pellet containing BSSG (3 mg) daily (5x/week) for 16 weeks consistent with previous reports of the model. Following BSSG intoxication, separate cohorts of animals (n=10/treatment) were exposed to a behavioural test battery at 16, 24, 32, or 40 weeks post initial BSSG feeding. The test battery consisted of the open field test, cylinder test, and ultrasonic vocalization (USV) assessment. No changes in behaviour were observed at any time point. Following behavioural testing, animals were processed for immunohistochemical markers of substantia nigra integrity. Immunohistochemistry of brain tissue revealed no differences in the microglial marker, Iba1, or the dopaminergic integrity marker, tyrosine hydroxylase (TH), in the substantia nigra at any assessment point. The absence of any group differences in behaviour and immunhistochemistry indicates an inability to replicate previous reports. Further investigation into the sources of variability in the model is necessary prior to further utilization of the BSSG model in preclinical studies.
Journal Article
A diffusion tensor imaging analysis of white matter microstructures in non-operated craniosynostosis patients
2022
Purpose
In 7 to 15-year-old operated syndromic craniosynostosis patients, we have shown the presence of microstructural anomalies in brain white matter by using DTI. To learn more about the cause of these anomalies, the aim of the study is to determine diffusivity values in white matter tracts in non-operated syndromic craniosynostosis patients aged 0–2 years compared to healthy controls.
Methods
DTI datasets of 51 non-operated patients with syndromic craniosynostosis with a median [IQR] age of 0.40 [0.25] years were compared with 17 control subjects with a median of 1.20 [0.85] years. Major white matter tract pathways were reconstructed with ExploreDTI from MRI brain datasets acquired on a 1.5 T MRI system. Eigenvalues of these tract data were examined, with subsequent assessment of the affected tracts. Having syndromic craniosynostosis (versus control), gender, age, frontal occipital horn ratio (FOHR), and tract volume were treated as independent variables.
Results
ʎ
2
and
ʎ
3
of the tracts genu of the corpus callosum and the hippocampal segment of the cingulum bundle show a
ƞ
2
> 0.14 in the comparison of patients vs controls, which indicates a large effect on radial diffusivity. Subsequent linear regressions on radial diffusivity of these tracts show that age and FOHR are significantly associated interacting factors on radial diffusivity (
p
< 0.025).
Conclusion
Syndromic craniosynostosis shows not to be a significant factor influencing the major white matter tracts. Enlargement of the ventricles show to be a significant factor on radial diffusivity in the tracts corpus callosum genu and the hippocampal segment of the cingulate bundle.
Clinical trial registration:
MEC-2014-461
Journal Article
Transient domoic acid excitotoxicity increases BDNF expression and activates both MEK- and PKA-dependent neurogenesis in organotypic hippocampal slices
2013
Background
We have previously reported evidence of cell proliferation and increased neurogenesis in rat organotypic hippocampal slice cultures (OHSC) after a transient excitotoxic injury to the hippocampal CA1 area induced by low concentrations of the AMPA/kainate agonist domoic acid (DOM). An increased baseline rate of neurogenesis may contribute to recovery from DOM-induced mild injury but the intracellular mechanism(s) responsible for neuronal proliferation remain unclear. The current study investigated the key intracellular pathways responsible for DOM-induced neurogenesis in OHSC including the effects of transient excitotoxicity on the expression of brain-derived neurotrophic factor (BDNF), a well-known regulator of progenitor cell mitosis.
Results
Application of a low concentration of DOM (2 μM) for 24 h followed by recovery induced a significant and long lasting increase in BDNF protein levels expressed by both neurons and microglial cells. Furthermore, the mild DOM toxicity stimulated both PKA and MEK-dependent intracellular signaling cascades and induced a significant increase in BDNF- transcription factor CREB activation and BDNF-receptor TrkB expression. Coexposure to specific inhibitors of PKA and MEK phosphorylation resulted in a significant decrease in the neurogenic marker doublecortin.
Conclusions
Our results suggest that transient excitotoxic insult induced by DOM produces BDNF and CREB overexpression via MEK and PKA pathways and that both pathways mediate, at least in part, the increased neural proliferation resulting from mild excitotoxicity.
Journal Article
Standardised ginseng extract G115® potentiates the antidepressant-like properties of fluoxetine in the forced swim test
by
Terstege, Dylan J.
,
Tasker, R. Andrew
,
MacDonald, Debra S.
in
Animals
,
Antidepressants
,
Anxiety
2021
Ginsenosides, biologically active components of the root of Panax ginseng, have been reported to have therapeutic benefits in a number of disease states including psychiatric conditions such as major depressive disorder. Our objective was to determine if a standardised commercial ginseng extract, G115®, could reduce the signs of behavioural despair commonly observed in animal models of depression either alone or in combination with the selective serotonin reuptake inhibitor (SSRI) fluoxetine.
Male Sprague-Dawley (SD) rats (N = 51) were divided into four groups: vehicle control, G115® ginseng root extract, fluoxetine and fluoxetine plus G115®. Rats were trained to voluntarily consume treatments twice daily for 14 days and were then tested in an open field (OF), elevated plus maze (EPM) and forced swim test (FST). Post-mortem hippocampal and prefrontal cortex tissue was analysed for expression of brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) by western blot.
One-way Analysis of Variance revealed no significant group differences in the OF or plus-maze performance on any variable examined. In the FST, fluoxetine significantly reduced immobility time and increased latency to immobility. The effects of fluoxetine were further significantly potentiated by co-administration of G115®. Post-mortem tissue analysis revealed significant group differences in BDNF expression in the left hippocampus and left prefrontal cortex without any accompanying changes in TrkB expression.
We conclude that oral G115® significantly potentiates the antidepressant-like effect of fluoxetine in the FST in the absence of potentially confounding effects on locomotion and anxiety.
Journal Article
Bilateral ischaemic lesions of the medial prefrontal cortex are anxiogenic in the rat
2018
Stroke patients often suffer from delayed disturbances of mood and cognition. In rodents, the prefrontal cortex (PFC) is involved in both higher order cognition and emotion. Our objective was to determine if bilateral focal ischaemic lesions restricted to the medial prefrontal cortex (mPFC) could be used to model post-stroke anxiety and/or cognitive deficits.
Groups of adult male Sprague-Dawley rats (n=9) received bilateral injections of either endothelin-1 (ET-1) (400 pmol) or vehicle (artificial cerebrospinal fluid) into the mPFC and were tested at various times using both a test of temporal order memory and in an elevated plus maze. Lesions were verified histologically.
ET-1 lesioned rats had reduced mobility on post-surgery day 8 that had resolved by day 29 at which time they spent significantly more time in the closed arm of the plus maze CONCLUSION: We conclude that ischaemic lesions localised to the mPFC can be used to model post-stroke anxiety in rats.
Journal Article