published_or_final_version / Diagnostic Radiology / Doctoral / Doctor of Philosophy

This study employed a new model of mild-to-moderate head trauma to specifically identify the role of dural mast cell (MC) histamine in trauma-induced increased permeability in the blood-brain barrier (BBB). A single line was scored partially through the left dorsal parietal skull. Immediately following the trauma, degranulation was seen in 39% of the MCs on the left and in 2% on the right. After a 20 min survival period, left duras showed 55% with MC degranulation (fewer with complete degranulation) compared to 34% on the right. In the other experiments two parallel lines were scored following the injection of Evan's blue. Histamine assay showed histamine increased in the left cortex to 154% at 5 min, 174% at 10 min, and 151% at 20 min. Fluorescent quantitation of extravasated Evan's blue at 20 min following the trauma gave an increase of 1385% over the value measured for the right cortex. Zolantidine, a selective histamine H2 receptor antagonist, administered at 10- and 20- mg/kg 30 min before the trauma blocked 65% of the Evan's blue extravasation compared with the control and 2.5 mg group.

Founded by the Fatimids in 970 A.D., al-Azhar has been described variously as "the great mosque of Islam," "the brilliant one," "a great seat of learning...whose light was dimmed." Yet despite its assumed centrality, the illustrious mosque-seminary has elicited little critical study. The existing historiography largely relies on colonial-nationalist teleologies that are grounded in a strong centrifugal essentialism: positioning Cairo (and al-Azhar) at a center, around which faithfully revolve concentric peripheries. Setting its focus on the eighteenth century and beyond, this dissertation investigates the discursive postulates that organize the writing of the history of al-Azhar. Through textual explorations that pivot in space and time, it elucidates shifts in the entanglement of disciplines of knowledge with those of the self at a particular historical juncture and location. It thus locates al-Azhar in the modern order of knowledge, even as it imagines another intellectual universe bound by ideas, texts and authors who lived before and outside Europe: one which articulated itself in conceptual, epistemic, moral, social, cultural and institutional ways, modernity as such cannot not capture.

Traumatic brain injury (TBI) is the signature injury of the ongoing military conflicts in the Middle East and Afghanistan, largely due to the use of improvised explosive devices (IEDs), which have affected soldiers and civilians alike. Blast-induced TBI (bTBI) biomechanics are complex and multiphasic. While research has clearly demonstrated the negative effects of penetrative (secondary blast) and inertia-driven (tertiary blast) injury, the effect of shock wave loading (primary blast) on the brain remains unclear. Combined primary-tertiary blast exposure in vivo has been reported previously to alter brain function, specifically hippocampal function; however, it is extremely difficult to deliver primary blast exposure in isolation with an in vivo injury model. The research presented in this thesis utilized a custom-designed in vitro blast injury model to deliver military-relevant shock wave exposures, in isolation, to organotypic hippocampal slice cultures (OHSCs). To contextualize blast-induced pathobiology with previous TBI studies, the first goal of this thesis was to experimentally characterize the deformation profile induced in OHSCs with our blast injury model. Using stereoscopic, high-speed cameras and digital image correlation to calculate strain, we found that our blast model induced low strain magnitudes (<9%) but at high strain rates (25-86s-1), which aligned closely with associated computational simulations of our model. The second aim was to determine if primary blast was capable of altering hippocampal electrophysiological function. We exposed OHSCs to a range of shock intensities and found, using a micro-electrode array system, that long-term potentiation (LTP), a measure of synaptic plasticity, was very sensitive to primary blast exposure; a threshold for disruption of LTP was found between 9 and 39 kPa•ms impulse. Alternative measures of basal electrophysiology were less sensitive than LTP. Blast exposure significantly reduced LTP between 1 and 24 hours post-injury, and this deficit persisted through 6 days post-injury. Depending on shock intensity, LTP spontaneously recovered 10 days post-injury. The third aim was to explore the cellular mechanisms for blast-induced LTP deficits. Using a chemical LTP induction protocol, blast exposure altered key proteins necessary for the induction of LTP by 24 hours post-injury including, postsynaptic density protein-95 (PSD-95), a major scaffolding protein that organizes the postsynaptic density (PSD), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptor 1 (AMPA-GluR1), and stargazin, an auxiliary GluR1 protein that binds AMPA-GluR1 to PSD-95. Modulation of the cyclic adenosine monophosphate (cAMP) pathway reversed the observed effects of blast on LTP. We theorized that blast-induced disruption of PSD-95 prevented translocation, and subsequent phosphorylation, of GluR1-containing AMPARs to the postsynaptic membrane, which, in turn, prevented potentiation. The final aim was to investigate the efficacy of phosphodiesterase-4 (PDE4) inhibitors, which block degradation of cAMP, as a therapeutic strategy. When delivered immediately following primary blast injury, multiple PDE4 inhibitors proved efficacious in restoring LTP measured 24 hours post-injury. Roflumilast, a Food and Drug Administration-approved PDE4 inhibitor, was effective when delivered at a clinically relevant concentration (1nM) and at a delayed time point (up to 6 hours). Roflumilast reversed blast-induced changes in expression/phosphorylation of the key LTP protein targets. We hypothesized that maintenance of PSD-95 drove the observed therapeutic effect. Greater work is necessary to determine how blast exposure degrades PSD-95 and how roflumilast prevented these detrimental effects. This thesis has shown that primary blast exposure can negatively alter neurological function, as well as protein expression and phosphorylation. These studies expand the understanding of primary blast injury mechanisms, provide computational models with important tissue-level tolerance criteria, inform protective equipment design, inform clinical care guidelines for bTBI, and present a promising therapeutic candidate for further clinical investigation.

Memory impairment is an outcome of Traumatic Brain Injury (TBI), and associated with lower levels of post-morbid adjustment. This research isolated the memory impairment of retrieval deficit, and examined the efficacy of cues and mnemonics in remediating the impairment. Thirty-three male and female TBI survivors, 18 to 71 years old, were pre-tested for attention (COPY), short-term memory (SD), long-term memory (LD) and recognition memory (RS) employing the Rey Osterrieth Complex Figure Test (CFT), and Subtest. Sixteen subjects demonstrating a retrieval deficit were administered the post-test, with even random assignment into four treatment conditions: a control group (CONTROL), a group administered cues (CUES), a group administered mnemonics {MNEM), and a group administered mnemonics and cues (BOTH) (n = 4). A MANOVA revealed a significant effect of TRIAL (p5.05), no significant effect of TREATMENT, and no interaction. A power analysis indicated the lack of TREATMENT effect could be the result of sample size. Post-hoc t tests revealed a difference across TRIAL for SD and LO in the two experimental conditions which utilized mnemonics. The sample was divided into two groups according to subjects' level of functioning (HIGH and LOW). A MANOVA showed main effects for LEVEL for SD and RS, for TRIAL for SD, LO, and RS, and a LEVEL by TRIAL interaction for COPY (R

Traumatic brain injury (TBI) is a major health and socioeconomic concern in the United States and across the globe. Experimental models of TBI are used to study the mechanisms underlying cell dysfunction and death that result from injury, the functional deficits that result from injury, and the potential of various therapies to treat injury. This thesis explores the fundamental mechanical damage associated with brain trauma, investigating the effects of mechanical deformation on neurons at the molecular, cellular, tissue, and animal levels. First, a novel hydrogel system was developed to support 3-D neuronal cultures, and the cultures were studied in an in vitro model of neuronal injury. The dependence of cell viability on hydrogel stiffness and extracellular matrix ligand concentration revealed a role for molecular interactions in the cellular response to injury. Subsequently, in a rat model of TBI neuronal plasma membrane damage was observed coincidentally with cell death within the hippocampus; however not all permeable cells died, suggesting a complex role for plasma membrane damage in neuronal degeneration. The spatial profile of permeable cells in the hippocampus reveals further heterogeneity of neuronal plasma membrane damage, with populations of cells in certain hippocampal subregions exhibiting an increased vulnerability to plasma membrane damage. These observations support recent finite element model predictions of strains in the brain during injury. Finally a system for measuring locomotor disturbances is used for the first time following brain injury. Continued investigation of how neurons deform and fail mechanically will contribute to the understanding of the pathophysiology of brain injury and may help identify potential therapeutic targets.

Traumatic brain injury (TBI) affects 1.4 million people a year in the United States alone and despite the fact that 96% of people survive a TBI, the health and socioeconomic consequences can be grave, partially due to the fact that very few clinical treatments are available to reduce the damage and subsequent dysfunction following TBI. To better understand the various mechanical, electrical, and chemical events during neural injury, and to elucidate specific cellular events and mechanisms that result in cell dysfunction and death, new high-throughput models are needed to recreate the environmental conditions during injury. This thesis project focuses on the creation of a novel and clinically relevant single-cell injury model of traumatic brain injury (TBI). The implementation of the model requires the development of a novel injury device that allows specialized micro-interfacing functionality with neural micro environments, which includes the induction of prescribed strains and strain rates onto neural tissue, such as groups of cells, individual cells, and cell processes. The device consists of a high-resolution micro-electro-mechanical-system (MEMS) microtweezer microactuator tool that is introducible into both biological and aqueous environments and can be proximally positioned to specific targets in neural tissue and neural culture systems. This microtweezer, which is constructed using traditional photolithography and micromachining processes, is controllable by a custom developed software-automated controller that incorporates a high precision linear actuator and utilizes a luer-based microtool docking interface. The injury studies will include examination of intracellular calcium concentration over the injury time course to evaluate neuronal plasma membrane permeability, which is a significant contributor to secondary injury cascades following initial mechanical insult. Mechanical strain and strain rate input tolerance criteria will also be used to determined thresholds for cellular dysfunction and death.

Biomarker research is of great interest in the field of traumatic brain injury (TBI), since there are numerous potential markers that may indicate central nervous system damage, yet the brain is normally well isolated and discovery is at its infancy. Traditional methods for biomarker discovery include time consuming multi step chromatographic mass spectrometery (MS) techniques or pre-defined serial probing using traditional assays, making the identification of biomarker panels limiting and expensive. These shortfalls have motivated the development of a MS based probe that can be embedded into 3D neural cultures and obtain temporal and spatial information about the release of biomarkers. Using the high sensitivity MS ionization method of nano-electrospray ionization (nano-ESI) with an in-line microdialysis (MD) unit allows us to use MS to analyze low concentrations of TBI biomarkers from within cell cultures with no need for off-line sample manipulation. This thesis goes through the development of the probe by studying the theoretical principles, simulations and experimental results of the probe's capability to sample small local concentrations of a marker within cell culture matrix, the MD unit's sample manipulation capabilities, and the ability to detect markers using in-line MD-nano-ESI MS.

Brain damage in the first week of life is behaviorally and anatomically devastating for a rat. I investigated the use of pre- and/or postnatal experience as interventions that might improve the outcomes in rats with postnatal day 4 (P4) frontal cortex lesions. Prenatal maternal tactile stimulation or maternal complex housing facilitated recovery in P4 lesion animals and produced changes in brain organization. Post-lesion tactile stimulation also was found to be beneficial possibly via experience dependent changes in FGF-2 expression. Levels of FGF-2 were increased in both skin and brain after tactile stimulation and correlated with behavioral and anatomical changes. Direct post-lesion administration of FGF-2 had similar effects. These results are the first demonstration that prenatal experience can be prophylactic for postnatal brain injury and that behavioral experience can act on brain organization via enhanced trophic factor expression originating in skin. / xxi, 221 leaves : ill. ; 28 cm.

Basic fibroblast growth factor (FGF-2) is a trophic molecule involved in a number of functions within the central nervous system (CNS), including a prominent role in the regulation of CNS responses to injury. Prior studies suggest that rats recover differently from injury inflicted to different regions and at different ages throughout development, and that FGF-2 might underlie this phenomenon. This thesis examined whether the functional and structural outcome following bilateral injury to the motor cortex inflicted at postnatal day (P10) could be ameliorated by exogenous administration of a growth factor (FGF-2). Four complimentary studies were conducted that each assessed the role of FGF-2 in mediating recovery from bilateral motor cortex injury inflicted at P10. We found that FGF-2 improves physiological, anatomical, and functional outcome from bilateral lesions to motor cortex at P10. / xiii, 171 p. : ill. ; 28 cm.