<p>Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that results in a myriad of physical and mental symptoms. Current disease-modifying therapies do not prevent long-term disability accumulation and are particularly ineffective for patients with a progressive disease onset. Exercise may represent an alternative strategy for managing symptoms and disability accumulation, particularly in progressive MS.</p> <p>Whereas the benefits of exercise have been established primarily in ambulatory MS patients with a relapsing disease course, few studies have investigated the benefits of exercise for patients with progressive MS with greater impairment. Therefore, the purpose of this dissertation was to determine the short-term, long-term, and maintenance effects of adapted exercise interventions for patients with progressive MS of high disability which was addressed by conducting two adapted exercise interventions.</p> <p>The first intervention examined the effects of 24 weeks of body weight supported treadmill training (BWSTT) on outcomes of physical and mental functioning, fatigue, quality of life, and brain health. Outcomes were evaluated at baseline, 12, and 24 weeks following the intervention, and again 12 weeks post-intervention. The second intervention evaluated and compared the effects of 12 weeks of total-body recumbent stepper training (TBRST) to BWSTT on outcomes of safety, physical and mental functioning, fatigue, quality of life, and equipment preference.</p> <p>Safety of BWSTT and TBRST was established. Significant improvements in fatigue and QoL were observed with both training modalities; however, neither significantly improved physical function. There was some evidence to suggest long-term BWSTT may improve cognitive performance and brain health, and that TBRST was the preferred exercise modality. Furthermore, most beneficial effects of long-term BWSTT tended not to be maintained when exercise was discontinued.</p> <p>This dissertation established evidence for the potential benefits of BWSTT and TBRST in patients with progressive MS with high disability. BWSTT and TBRST may represent viable alternative strategies for disease management.<strong></strong></p> / Doctor of Philosophy (PhD)

<p>Huntington’s disease (HD) is a progressive, neurodegenerative disorder that leads to the selective loss of neurons in the striatum and the cerebral cortex. HD is caused by a CAG trinucleotide repeat expansion beyond the normal length in the <em>IT15 </em>(<em>Htt</em>) gene. The CAG stretch codes for an elongated polyglutamine tract within the amino‐terminus of the huntingtin protein. Polyglutamine tracts with lengths exceeding 37 repeats cause HD whereas repeat lengths below do not. This phenomenon has plagued the HD community since the discovery of the gene in 1993. In this thesis, we sought to elucidate the molecular mechanism by which huntingtin becomes toxic at polyglutamine lengths above 37. Using Förster resonance energy transfer (FRET) techniques, we describe an intramolecular proximity between the first 17 residues (N17) and the proline-rich regions, which flank the polyglutamine tract of huntingtin. We report that we can precisely measure differences between the conformations adopted by the huntingtin protein with polyglutamine tracts below and above the pathogenic repeat threshold of 37 repeats. Our data supports the hypothesis that polyglutamine tracts below the pathogenic threshold can act as a flexible hinge allowing the N17 domain to freely fold back upon huntingtin and come into close 3D proximity with the polyproline region. This flexibility is lost in polyglutamine tracts with >37 repeats resulting in a diminished spatial proximity between N17 and the polyproline domain.</p> / Doctor of Philosophy (PhD)

Stroke is a leading cause of long-term disability, affecting thousands of individuals annually and significantly impairing their mobility, independence, and quality of life. Traditional methods for assessing motor impairments are often costly and invasive, creating substantial barriers to effective rehabilitation. This thesis explores the use of DeepLabCut (DLC), a deep-learning-based pose estimation tool, to extract clinically meaningful kinematic features from video data of stroke survivors with upper-extremity (UE) impairments. To conduct this investigation, a specialized protocol was developed to tailor DLC for analyzing movements characteristic of UE impairments in stroke survivors. This protocol was validated through comparative analysis using peak acceleration (PA), mean squared jerk (MSJ), and area under the curve (AUC) as kinematic features. These features were extracted from the DLC output and compared to those derived from the assumed ground-truth data from IMU sensors worn by the participants. The accuracy of this analysis was quantified using percent mean squared error (PMSE) between each IMU sensor and DLC. PMSE analysis indicates that DLC-based kinematic features capture aspects of both accelerometer and gyroscope for the control participant. PA (8.78%) and AUC (3.28%) align more closely with the gyroscope, while MSJ (5.20%) demonstrates greater agreement with the accelerometer. On the other hand, for the stroke participant, DLC estimations for all kinematic features predominantly reflect data from the accelerometer. Across all datasets, AUC has the smallest PMSE values, suggesting that, based on our data, motor effort and energy expenditure in the tasks are best represented by DLC. Additionally, PMSE values for the stroke dataset are higher than those for the control, highlighting DLC's limitations in accurately detecting finer details of motion data in individuals with UE impairments. The results indicate that DLC reasonably estimates kinematic data for both participants, although further refinement of the methods is necessary to enhance the analysis of stroke data.

The dysregulation of immune system function has been centrally implicated in numerous age-related and neurodegenerative disorders, including Alzheimer’s disease (AD). Genetic susceptibility studies have positioned microglia, brain-resident immune cells, as critical actors in the development and the progression of the disease. Microglia are highly plastic cells with diverse functions across many modalities, and the appropriate regulation of their activities are a prerequisite for central nervous system homeostasis and cognitive health. Aging and pathogenic contexts are posited to modify microglial behavior, inhibiting their neuroprotective function and promoting a dysfunctional state that drives disease. However, the mechanisms underlying these pathogenic alterations in microglial state and function are complex and poorly understood. This thesis identifies three elements that are altered in the AD brain and investigates how these mechanisms may serve as triggers producing microglial dysregulation in AD. Chapter 3 examines the role of expression of the transposable element LINE-1 in AD-related microglial dysfunction. Chapter 4 explores the regulation of PLCG2, which encodes a critical AD-associated signaling enzyme. Chapter 5 investigates the role of the AD-linked sorting receptor SORL1 in microglia. Together, these data expand our understanding of mechanisms driving altered microglial pathophysiology in AD and illuminate pathways of interest with potential therapeutic applications meriting deeper exploration.

Thesis (DPhil)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This qualitative study comprised an in-depth investigation into the subjective - the explicitly human - experience of those suffering from Myalgic Encephalomyelitis (ME). I was, firstly, concerned with the nature and meaning of the social side of illness, that is, the sufferer's encounters with doctor, family member, friend and acquaintance alike. I was, secondly, set to develop greater insight into the essentially personal experience of being ill. I was able to conclude that, even amidst the inhumane presence of utter ignorance that permeate the very experience of ME, no ME sufferer is inevitably doomed a victim. They can always make a deliberate decision to have a say in their situation, in their own experience of their circumstances. They have the power of personal choice. Recommendations are, therefore, directed at expanding the potential extent and magnitude of this dynamic power. The substantive focus of my study was enriched by a deliberate concern with the methodological implications of my own intimate involvement within the research process. I was here primarily concerned with my personal contribution to the research process as well as the influence thereof on the research relationships developed and the research strategies chosen and applied. I could not but conclude that the understanding I explicate is, as all social science theory, essentially a human construction, developed by me, in my distinctly human capacity. Recommendations are, therefore, geared to sensitise all social researchers to their own contribution to the construction of that which is eventually presented (and taken) as truthful knowl~dge. In conclusion, I am thoroughly convinced that the experience of both illness and research is fundamentally human. This "humanness" cannot and should not be denied. Instead, I advocate a more deliberate focus on the human dimension of illness and research. Without such a focus, a more comprehensive understanding of either realm will continue to linger as but an elusive ideal. / AFRIKAANSE OPSOMMING: Hierdie kwalitatiewe studie is gebaseer op 'n in-diepte ondersoek gerig op die subjektiewe - die onteenseglik menslike - ervaring van diegene wat ly aan Myaligië Enkefalomiëlitis (ME). Ek was, eerstens, geïnteresseerd in die aard en betekenis van die sosiale dimensie van siekte, dit wil sê, die lyer se ervaring van sosiale kontak met dokters, gesinslede, vriende en kennisse. Ek was, tweedens, gerig op die ontwikkeling van 'n grondige insig in die uiters persoonlike ervaring van siek-wees. Ek het tot die gevolgtrekking gekom dat, selfs te midde van die onmenslike teenwoordigheid van blatante onkunde wat die ganse ervaring van ME kenmerk, geen ME lyer noodwendig tot 'n slagoffer-status gedoem is nie. Hulle kan altyd 'n doelbewuste besluit neem om 'n sê te hê in hul eie situasie, in hul eie ervaring van hul omstandighede. Hulle het die mag van persoonlike keuse. Aanbevelings is dus daarop gerig om die potentiële trefwydte en impak van hierdie dinamiese mag uit te brei. Die substantiewe dimensie van my studie is verryk deur 'n doelbewuste fokus op die metodologiese implikasies van my eie intieme betrokkenheid in die navorsingsproses. Ek was hoofsaaklik gemoeid met my persoonlike bydrae tot die navorsingsproses en die invloed daarvan op die ontwikkel van navorsingsverhoudings en die toepassing van gekose navorsingstrategieë. Hierdie fokus het gelei tot die besef dat die beskrywing wat ek aanbied, soos inderdaad alle sosiale teorie, essensieël 'n menslike konstruksie is, soos ontwikkel deur my, in my uitdruklik menslike kapasiteit. Aanbevelings is dus daarop gerig om alle sosiale navorsers te sensitiseer ten opsigte van hul eie bydrae tot die konstruksie van dit wat uiteindelik voorgestel (en geag) word as die waarheidsgetroue kennis. In slotsom, is ek oortuig dat die ervaring van beide siekte en navorsing fundamenteel menslik is. Hierdie "mensheid" kan en behoort nie ontken te word nie. Inteendeel, ek bepleit 'n doelbewuste fokus op die menslike dimensie van siekte en navorsing. Sonder só 'n fokus sal 'n meer diepgaande begrip van iedere area bloot 'n onbereikbare ideaal bly.

Blast-induced traumatic brain injury (bTBI) has been described as the defining injury of Operations Enduring Freedom and Iraqi Freedom (OEF/OIF). Previously, most blast injury research has focused on the effects of blast on internal, gas filled organs due to their increased susceptibility. However, due to a change in enemy tactics combined with better armor and front-line medical care, bTBI has become one of the most common injuries due to blast. Though there has been a significant amount of research characterizing the brain injury produced by blast, a sound understanding of the contribution of each component of the shockwave to the injury is needed. Large animal models of bTBI utilize chemical explosives as their shockwave source while small animal models predominantly utilize compressed air-driven membrane rupture as their shockwave source. We designed and built a multi-mode shock tube capable of utilizing compressed gas (air or helium)-driven membrane rupture or chemical explosives (oxyhydrogen – a 2:1 mixture of hydrogen and oxygen gasses, or RDX – high order explosive) to produce a shockwave. Analysis of the shockwaves produced by each mode of the McMillan Blast Device (MBD) revealed that compressed air-driven shockwaves exhibited longer duration positive phases than compressed helium-, oxyhydrogen-, or RDX-driven shockwaves of similar peak overpressure. The longer duration of compressed air-driven shockwaves results in greater energy being imparted on a test subject than would be imparted by shockwaves of identical peak overpressures from the other sources. Animals exposed to compressed air-driven shockwaves exhibited more extensive brain surface hematoma, more blood-brain barrier compromise, more extensive reactive astrocytosis, and greater numbers of activated microglia in their brains than did animals exposed to oxyhydrogen-driven shockwaves of even greater peak overpressure. Taken together, these data suggest that compressed air-driven shockwaves contain more energy than their chemical explosive-derived counterparts of equal peak overpressure and can result in greater injury in an experimental animal model. Additionally, these data suggest that exposure to longer duration shockwaves, which is common in certain realworld scenarios, can result in more severe bTBI. The results of this study can be used to aid design of blast wave mitigation technology and future clinical intervention.

Noninvasive assessment of diabetic cardiovascular autonomic neuropathy (AN): Cardiac and vascular dysfunctions resulting from AN are complications of diabetes, often undiagnosed. Our objectives were to: 1) determine sympathetic and parasympathetic components of compromised blood pressure regulation in patients with polyneuropathy, and 2) rank noninvasive indexes for their sensitivity in diagnosing AN. Continuous 12-lead electrocardiography (ECG), blood pressure (BP), respiration, regional blood flow and bio-impedance were recorded from 12 able-bodied subjects (AB), 7 diabetics without (D0), 7 with possible (D1) and 8 with definite polyneuropathy (D2), during 10 minutes supine control, 30 minutes 70-degree head-up tilt and 5 minutes supine recovery. During the first 3 minutes of tilt, systolic BP decreased in D2 while increased in AB. Parasympathetic control of heart rate, baroreflex sensitivity, and baroreflex effectiveness and sympathetic control of heart rate and vasomotion were reduced in D2, compared with AB. Baroreflex effectiveness index was identified as the most sensitive index to discriminate diabetic AN. Four-dimensional multiscale modeling of ECG indexes of diabetic autonomic neuropathy: QT interval prolongation which predicts long-term mortality in diabetics with AN, is well known. The mechanism of QT interval prolongation is still unknown, but correlation of regional sympathetic denervation of the heart (revealed by cardiac imaging) with QT interval in 12-lead ECG has been proposed. The goal of this study is to 1) reproduce QT interval prolongation seen in diabetics, and 2) develop a computer model to link QT interval prolongation to regional cardiac sympathetic denervation at the cellular level. From the 12-lead ECG acquired in the study above, heart rate-corrected QT interval (QTc) was computed and a reduced ionic whole heart mathematical model was constructed. Twelve-lead ECG was produced as a forward solution from an equivalent cardiac source. Different patterns of regional denervation in cardiac images of diabetic patients guided the simulation of pathological changes. Minimum QTc interval of lateral leads tended to be longer in D2 than in AB. Prolonging action potential duration in the basal septal region in the model produced ECG and QT interval similar to that of D2 subjects, suggesting sympathetic denervation in this region in patients with definite neuropathy.

Due to the blood-brain barrier, delivery of many drugs to the brain has required intracranial surgery which is prone to complication. Here we show that Dopamine Neuron Stimulating Peptide 11 (DNSP-11), following non-invasive intranasal administration, protects dopaminergic neurons from a lesion model of Parkinson’s disease in the rat. A significant and dose-dependent increase in an index of dopamine turnover (the ratio of DOPAC to dopamine) was observed in the striatum of normal young adult Fischer 344 rats by whole-tissue neurochemistry compared to vehicle administered controls. Among animals challenged with a moderate, unilateral 6-hydroxy-dopamine (6-OHDA) lesion of the substantia nigra, those treated repeatedly with intranasally administered DNSP-11 exhibited greater numbers of tyrosine hydroxylase (TH) positive dopaminergic neuronal cell bodies in the substantia nigra and greater TH+ fiber density in the striatum when compared to animals treated intranasally with vehicle only or a scrambled version of the DNSP-11 sequence. Lesioned animals that received intranasal DNSP-11 treatment did not exhibit abnormal, apomorphine-induced rotation behavior, contrasted with animals that received only vehicle or scrambled peptide that did exhibit significantly greater rotation behavior. In addition, the endogenous expression of DNSP-11 from the pro-region of GDNF was investigated by immunohistochemistry with a custom, polyclonal antibody. Signal from the DNSP-11 antibody was found to be differentially localized from the mature GDNF protein both spatially and temporally. While DNSP-11-like immunoreactivity extensively colocalizes with GDNF immunoreactivity at post-natal day 10, the day of maximal GDNF expression, DNSP-11-like signal was found to be present in the 3 month old rat brain with signal in the substantia nigra, ventral thalamic nucleus, dentate gyrus of the hippocampus, with the strongest signal observed in the locus ceruleus where GDNF is not expressed. Results from immunoprecipitation of brain homogenate were not consistent with the synthetic, amidated 11 amino-acid rat DNSP-11 sequence. However, binding patterns in the literature of NPY, the only homologous sequence present in the CNS, do not recapitulate the immunoreactive patterns observed for the DNSP-11 signal. This study provides evidence for a potential easy-to-administer intranasal therapeutic using the DNSP-11 peptide for protection from a 6-OHDA lesion rat model of Parkinson’s disease.

Compte-tenu de l’importance des populations exposées, les effets à long terme des pesticides sont un enjeu de santé publique majeur. Leur étude pose néanmoins des problèmes méthodologiques complexes. Notre objectif était de contribuer à la connaissance des effets chroniques des pesticides sur le système nerveux central en explorant par une approche épidémiologique innovante le rôle des insecticides organophosphorés dans l’apparition de troubles cognitifs. Nous avons développé et utilisé deux outils de mesure de l’exposition (une matrice culture-exposition : PESTIMAT, et des algorithmes basés sur des études de terrain : PESTEXPO) afin d’estimer l’exposition à 34 insecticides organophosphorés utilisés en vigne, en considérant pour chaque individu l’ensemble des tâches viticoles exposant aux pesticides (préparation, application, nettoyage, réentrée) réalisées au cours de sa vie. Ces outils ont été appliqués dans le cadre du premier suivi (2001-2003) de la cohorte PHYTONER constituée en 1997 par l’inclusion de 925 affiliés à la Mutualité Sociale Agricole de Gironde. L’exposition aux organophosphorés définie par des index cumulés à l’aide de nos deux outils était associée à une baisse des performances cognitives, de manière plus marquée pour les tests explorant la mémoire de travail visuelle et la vitesse de traitement de l’information. Les niveaux de risque variaient en fonction des organophosphorés et étaient plus marqués pour le mévinphos. Cette thèse a confirmé le risque de troubles cognitifs chez les utilisateurs professionnels de pesticides et pose la question d’une évolution ultérieure vers une démence. Elle a également démontré la faisabilité et la pertinence d’une approche s’attachant à établir des scores d’exposition à des matières actives pesticides spécifiques pour en analyser les effets de santé. / Given the number of exposed persons, long term effects of pesticides are a foremost Public Health concern. However their study raises complex methodological issues. Our objective was to contribute to the knowledge of the pesticide chronic effects on the central nervous system by exploring the role of organophosphate insecticides in occurence of cognitive disorders by an innovative epidemiological approach. Two exposure assessment tools were developed (a crop exposure matrix: PESTIMAT and algorithms based on field studies: PESTEXPO) to estimate the lifetime cumulated exposure to 34 organophosphate insecticides used in vineyards, taking into account pesticide exposure during tasks (mixing, spraying, cleaning, re-entry) performed by wine-growers. These tools were used in the framework of the first follow-up (2001-2003) of the PHYTONER cohort, initiated in 1997 by the enrollment of 925 workers affiliated to the farmer health insurance system in Gironde, France. Cumulative organophosphate exposure defined by an index using the two tools was associated with poor cognitive performances, particularly for tests exploring the visual working memory and the processing speed. Risk level varied depending on the organophosphate, and was more pronounced for mevinphos. This thesis supports the hypothesis that cognitive impairment may be associated with pesticide occupational use and raises the question of a further evolution towards dementia. It also demonstrated the feasibility and the relevance of an approach based on chemical specific exposure scores to analyze health effects.

Stroke is the 5th leading cause of death in the U.S. with 130,000 deaths and around 800,000 affected annually. Currently, there is a significant disconnect between basic stroke research and clinical stroke therapeutic needs. Few animal models of stroke target the large vessels that produce cortical deficits seen in the clinical setting. Also, current routes of drug administration, intraperitoneal and intravenous, do not mimic the clinical route of intra-arterial drug administration. To bridge this divide, we have retro-engineered a mouse model of stroke from the current standard of care for emergent large vessel occlusion (ELVO) stroke, endovascular thrombectomy, to include selective intra-arterial pharmacotherapy administration. Using the tandem transient common carotid and middle cerebral artery occlusion (MCAo) model to induce stroke, we threaded micro-angio tubing into the external carotid artery (ECA) towards the bifurcation of the common carotid and internal carotid arteries (CCA/ICA) allowing for the delivery of agents to the site of acute ischemia. Our model was optimized through a flow rate and injection volume study using carbon black ink injected through the intra-arterial model at different flow rates and injection volumes. The purpose of this study was to demonstrate that our injections were arriving at the site of ischemia and to improve injection volumes for future dosing while mitigating systemic side effects by preventing or minimizing systemic distribution. We determined that a flow rate of 2.5 µl/minute and injection volume of 10 µl was optimal. Next, we tested potential neuroprotective compounds nitroglycerin, verapamil, and a combination of verapamil and lubeluzole. Compounds were chosen for drug synergy and to target specific pathways in either an acute or delayed manner. Acute treatments included nitroglycerin and/or verapamil while delayed treatment included lubeluzole. The known mechanism of action for FDA approved nitroglycerin is through vessel dilation that results in increased blood flow to the treated region. A secondary mechanism of nitroglycerin is the production of nitric oxide, which has demonstrated antioxidant and anti-apoptotic effects when processed and released from cells surrounding the blood vessels. Verapamil, a calcium channel blocker, also FDA-approved for cerebral artery vasospasm: is thought to act by blocking the L-type calcium channels on the cell membrane from opening following membrane depolarization after insult. Finally, lubeluzole, also FDA-approved, is proposed to work as an NMDA modulator inhibiting the release of glutamate and nitric oxide synthase and blocking sodium and calcium channels. Through our stroke model we were able to demonstrate that each drug(s) showed a significant decrease in infarct volume and improved functional recovery while simultaneously minimizing potential systemic side effects suggesting that our stroke model may improve the preclinical validation of potential stroke therapies and help bridge the bench to bedside divide in developing new stroke therapies.