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Search Results: 1 - 10 of 224650 matches for " Kimberly R Byrnes "
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Delayed mGluR5 activation limits neuroinflammation and neurodegeneration after traumatic brain injury
Kimberly R Byrnes, David J Loane, Bogdan A Stoica, Jiangyang Zhang, Alan I Faden
Journal of Neuroinflammation , 2012, DOI: 10.1186/1742-2094-9-43
Abstract: One month after controlled cortical impact traumatic brain injury, C57Bl/6 mice were randomly assigned to treatment with single dose intracerebroventricular CHPG, vehicle or CHPG plus a selective mGluR5 antagonist, 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine. Lesion volume, white matter tract integrity and neurological recovery were assessed over the following three months.Traumatic brain injury resulted in mGluR5 expression in reactive microglia of the cortex and hippocampus at one month post-injury. Delayed CHPG treatment reduced expression of reactive microglia expressing NADPH oxidase subunits; decreased hippocampal neuronal loss; limited lesion progression, as measured by repeated T2-weighted magnetic resonance imaging (at one, two and three months) and white matter loss, as measured by high field ex vivo diffusion tensor imaging at four months; and significantly improved motor and cognitive recovery in comparison to the other treatment groups.Markedly delayed, single dose treatment with CHPG significantly improves functional recovery and limits lesion progression after experimental traumatic brain injury, likely in part through actions at mGluR5 receptors that modulate neuroinflammation.Traumatic brain injury (TBI) causes cell death and neurological dysfunction through both direct physical disruption of tissue or pathways (primary injury), as well as delayed and potentially reversible molecular and cellular pathophysiological mechanisms (secondary injury) resulting in progressive white matter and grey matter damage [1]. Such delayed injury begins within seconds to minutes after the insult and may continue for days, weeks or potentially months to years [2]. These processes are characterized by neuronal cell death, as well as infiltration and activation of blood-borne immune cells, such as macrophages and lymphocytes, and activation of resident microglia [3].After TBI, microglia become activated and undergo marked changes in cell morphology and behavior. Upon acti
Delayed inflammatory mRNA and protein expression after spinal cord injury
Kimberly R Byrnes, Patricia M Washington, Susan M Knoblach, Eric Hoffman, Alan I Faden
Journal of Neuroinflammation , 2011, DOI: 10.1186/1742-2094-8-130
Abstract: Adult male rats were subjected to mild, moderate or severe spinal cord contusion injury at T9 using a well-characterized weight-drop model. Tissue from the lesion epicenter was obtained 4 hours, 24 hours, 7 days, 28 days, 3 months or 6 months post-injury and processed for microarray analysis and protein expression.Anchor gene analysis using C1qB revealed a cluster of genes that showed elevated expression through 6 months post-injury, including galectin-3, p22PHOX, gp91PHOX, CD53 and progranulin. The expression of these genes occurred primarily in microglia/macrophage cells and was confirmed at the protein level using both immunohistochemistry and western blotting. As p22PHOX and gp91PHOX are components of the NADPH oxidase enzyme, enzymatic activity and its role in SCI were assessed and NADPH oxidase activity was found to be significantly up-regulated through 6 months post-injury. Further, treating rats with the nonspecific, irreversible NADPH oxidase inhibitor diphenylene iodinium (DPI) reduced both lesion volume and expression of chronic gene cluster proteins one month after trauma.These data demonstrate that inflammation-related genes are chronically up-regulated after SCI and may contribute to further tissue loss.Spinal cord injury (SCI) is followed by delayed secondary damage that occurs for days, weeks and even months following the initial insult [1,2]. Inflammation, including the activation and migration of microglia and macrophages, plays a significant role in this secondary injury [3-9]. Microglia are the primary immune response cells in the CNS [10] and can be activated by a number of pro-inflammatory cytokines and chemokines or other alterations in the CNS environment [11,12]. Microglia respond quickly, within minutes, to environmental changes such as increases in ATP concentration or injury [13]. After SCI, microglia are the dominant monocyte occupying the injury site through 3 days post-injury, after which macrophages begin to invade the lesion site [14
FDG-PET imaging in mild traumatic brain injury: A critical review
Kimberly R. Byrnes,Colin Wilson,Fiona Brabazon,Ramona von Leden,Jennifer Jurgens,Terrence R. Oakes,Reed Selwyn
Frontiers in Neuroenergetics , 2013, DOI: 10.3389/fnene.2013.00013
Abstract: Traumatic brain injury (TBI) affects an estimated 1.7 million people in the United States and is a contributing factor to one third of all injury related deaths annually. According to the CDC, approximately 75% of all reported TBIs are concussions or considered mild in form, although the number of unreported mild TBIs and patients not seeking medical attention is unknown. Currently, classification of mild TBI (mTBI) or concussion is a clinical assessment since diagnostic imaging is typically inconclusive due to subtle, obscure, or absent changes in anatomical or physiological parameters measured using standard magnetic resonance (MR) or computed tomography (CT) imaging protocols. Molecular imaging techniques that examine functional processes within the brain, such as measurement of glucose uptake and metabolism using [18F]fluorodeoxyglucose and positron emission tomography (FDG-PET), have the ability to detect changes after mild TBI. Recent technological improvements in the resolution of PET systems, the integration of PET with MRI, and the availability of normal healthy human databases and commercial image analysis software contribute to the growing use of molecular imaging in basic science research and advances in clinical imaging. This review will discuss the technological considerations and limitations of FDG-PET, including differentiation between glucose uptake and glucose metabolism and the significance of these measurements. In addition, the current state of FDG-PET imaging in assessing mild TBI in clinical and preclinical research will be considered. Finally, this review will provide insight into potential critical data elements and recommended standardization to improve the application of FDG-PET to mild TBI research and clinical practice.
The Current Role of Carotid Duplex Ultrasonography in the Management of Carotid Atherosclerosis: Foundations and Advances
Kelly R. Byrnes,Charles B. Ross
International Journal of Vascular Medicine , 2012, DOI: 10.1155/2012/187872
Abstract: The management of atherosclerotic carotid occlusive disease for stroke prevention has entered a time of dramatic change. Improvements in medical management have begun to challenge traditional interventional approaches to asymptomatic carotid stenosis. Simultaneously, carotid artery stenting (CAS) has emerged as an alternative to carotid endarterectomy (CE). Finally, multiple factors beyond degree of stenosis and symptom status now mitigate clinical decision making. These factors include brain perfusion, plaque morphology, and patency of intracranial collaterals (circle of Willis). With all of these changes, it seems prudent to review the role of carotid duplex ultrasonography in the management of atherosclerotic carotid occlusive disease for stroke prevention. Carotid duplex ultrasonography (CDU) for initial and serial imaging of the carotid bifurcation remains an essential component in the management of carotid bifurcation disease. However, correlative axial imaging modalities (computer tomographic angiography (CTA) and contrast-enhanced magnetic resonance angiography (CE-MRA)) increasingly aid in the assessment of individual stroke risk and are important in treatment decisions. The purpose of this paper is twofold: (1) to discuss foundations and advances in CDU and (2) to evaluate the current role of CDU, in light of other imaging modalities, in the clinical management of carotid atherosclerosis. 1. Introduction Carotid atherosclerosis is one of several etiological factors for stroke, an important health problem with a high burden of disease in the western world and in developing countries. Of all strokes, an estimated 88% are ischemic in nature [1–5]. Less than 20% of these are caused by atheroma in the carotid bifurcation [6–8]. While the percentage of strokes attributed to carotid disease is relatively low, the overall social and economic burden is high. It is, therefore, important to identify and manage carotid atherosclerosis with the aim of stroke prevention. The mortality rate for stroke in the United States has declined by nearly 70% since 1950 [9]. In December 2010, the Center for Disease Control and Prevention announced stroke was the fourth leading cause of death in the United States (down from its third place ranking which it held for decades) [10]. The identification of major risk factors through population-based studies [1, 11, 12] and randomized controlled trials (RCTs) of symptomatic [13–15] and asymptomatic [16, 17] patients has led to effective public health and clinic-based control strategies. These strategies include combining
Preparing Leaders in Public Health for Success in a Flatter, More Distributed and Collaborative World
John R. Kimberly
Public Health Reviews , 2011,
Abstract: In a world that is rapidly changing, what are the challenges for which leaders in public health in the future need to be prepared, what are the qualities and skills they will need for success, and where will they get the training they require? Addressing each of these questions in succession, this article contends that success in a flatter, more distributed and collaborative world will require a new generation of leaders in public health with new mindsets, an appetite for innovation and interdisciplinary collaboration and a strong dose of political savvy. Faculty, curricula and com-petencies in academic centers play an important role in this equation.
Editorial on the Status of Hernia Surgery Back to Pure Tissue Repair or Forward to Tohubohu  [PDF]
Earl Byrnes Shouldice
International Journal of Clinical Medicine (IJCM) , 2014, DOI: 10.4236/ijcm.2014.513100

Edoardo Bassini is considered the father of modern surgery. His early results revealed a 2.7% recurrence rate. Earl Shouldice, his true successor, has improved the results to less than 1%. These results were produced by several well-known surgeons from 1970-2000 and well published. The need for mesh was meant for a small segment of the surgical patient population. What has happened? Generally, recurrence rates with mesh have not come down; instead, pain has become the bane of hernia repair as we begin the 21st century. A pain which makes the patient wish that he had a recurrence instead!

Density Matrix Renormalization Group Approach to the Massive Schwinger Model
T. Byrnes,P. Sriganesh,R. J. Bursill,C. J. Hamer
Physics , 2002, DOI: 10.1016/S0920-5632(02)01416-0
Abstract: The massive Schwinger model is studied, using a density matrix renormalization group approach to the staggered lattice Hamiltonian version of the model. Lattice sizes up to 256 sites are calculated, and the estimates in the continuum limit are almost two orders of magnitude more accurate than previous calculations. Coleman's picture of `half-asymptotic' particles at background field (theta = pi) is confirmed. The predicted phase transition at finite fermion mass (m/g) is accurately located, and demonstrated to belong in the 2D Ising universality class.
One and Two Dimensional Spin Systems in the Regime Close to Deconfinement of Spinons
T. M. R. Byrnes,M. T. Murphy,O. P. Sushkov
Physics , 1999, DOI: 10.1103/PhysRevB.60.4057
Abstract: Based on the Majumdar-Ghosh chain we construct several spin models which allow us to investigate spinon dynamics in the regime close to deconfinement of spinons. We consider the J_1 - J_2 - \delta model, two coupled J_1 - J_2 chains (ladder), and a 2D array of coupled J_1 - J_2 chains. Using the picture of two spinons interacting with a string confining potential we calculate the singlet- triplet splitting, magnetic structure factor, tunneling amplitude of two spinons and the excitation spectra for the ladder and the array.
Comprehensive analysis of the simplest curvaton model
Christian T. Byrnes,Marina Cortês,Andrew R. Liddle
Physics , 2014, DOI: 10.1103/PhysRevD.90.023523
Abstract: We carry out a comprehensive analysis of the simplest curvaton model, which is based on two non-interacting massive fields. Our analysis encompasses cases where the inflaton and curvaton both contribute to observable perturbations, and where the curvaton itself drives a second period of inflation. We consider both power spectrum and non-Gaussianity observables, and focus on presenting constraints in model parameter space. The fully curvaton-dominated regime is in some tension with observational data, while an admixture of inflaton-generated perturbations improves the fit. The inflating curvaton regime mimics the predictions of Nflation. Some parts of parameter space permitted by power spectrum data are excluded by non-Gaussianity constraints. The recent BICEP2 results [1] require that the inflaton perturbations provide a significant fraction of the total perturbation, ruling out the usual curvaton scenario in which the inflaton perturbations are negligible, though not the admixture regime where both inflaton and curvaton contribute to the spectrum.
Density Matrix Renormalisation Group Approach to the Massive Schwinger Model
T. Byrnes,P. Sriganesh,R. J. Bursill,C. J. Hamer
Physics , 2002, DOI: 10.1103/PhysRevD.66.013002
Abstract: The massive Schwinger model is studied, using a density matrix renormalisation group approach to the staggered lattice Hamiltonian version of the model. Lattice sizes up to 256 sites are calculated, and the estimates in the continuum limit are almost two orders of magnitude more accurate than previous calculations. Coleman's picture of `half-asymptotic' particles at background field theta = pi is confirmed. The predicted phase transition at finite fermion mass (m/g) is accurately located, and demonstrated to belong in the 2D Ising universality class.
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