Dissertations / Theses on the topic 'Structural alterations'

Fibromyalgia syndrome (FMS) is a widespread chronic pain disorder affecting 2−5% of the general population and particularly women of middle age (McBeth and Mulvey, 2012). The syndrome is frequently comorbid with a variety of clinical, functional and psychological disorders (Weir et al., 2006) and associated with a large socio-economic burden (Lachaine et al., 2010). In spite of significant previous research, the underlying aetiology and pathophysiology of FMS is not fully understood (Schmidt-Wilcke and Clauw, 2011). However, aberrant structural and functional brain alterations have been proposed as a casual or maintaining factor of the disorder (Schweinhardt et al., 2008). This thesis utilised functional and structural imaging methods and novel experimental paradigms to explore brain alterations in FMS patients. A comprehensive review of previous experimental findings was performed to identify novel research questions. EEG and MRI data for 5 unique studies was collected over two sessions. In the first study dynamic mechanical stimulation was applied to the forearm of FMS patients and healthy participants, and an ERD analysis of corresponding EEG data was performed. The results revealed that FMS patients exhibited alterations to cortical excitability during brushing stimuli which correlated with clinical measures. These findings indicate that abnormal processing of innocuous somatosensory stimulation may contribute to the pathophysiology and clinical symptom severity of FMS. Secondly, an ERP analysis of EEG data from the observation of pain and non-pain pictures was performed. FMS patients exhibited differences in ERP components and source activation patterns during observation of pain pictures relative to healthy people. Alterations to processing of observed pain occurred in parahippocampal gyrus and may relate to clinical and psychological aspects of FMS, this finding could be utilised to further understand the heterogeneity of psychological profiles of FMS patients in order to better target therapeutic interventions. The third study of the thesis describes a novel comparison of functional connectivity with resting-state network structures utilising fMRI recordings. Functional connectivity with default mode network structures was shown to be altered in FMS. This finding may reflect an ongoing time-dependent reorganisation of resting-state networks due to ongoing chronic pain. In the fourth study, a morphological analysis of subcortical structures was performed using high-resolution T1-weighted MR images. FMS patients demonstrated alterations to the morphology of the brainstem, an important structure in descending nociceptive control. Volumetric alterations in this structure correlated with clinical measures of symptom severity suggesting an important role for brainstem alterations in FMS pain symptoms. In the final study the microstructural integrity of white matter was compared between FMS patients and healthy participants. Although no significant differences were identified the findings indicate that FMS is not likely to be related to abnormal development of white matter tracts. Therefore structural alterations associated with FMS are likely to occur only in the grey matter.

The thesis investigated progression of the central 10° visual field with structural changes at the macula in a cross-section of patients with varying degrees of agerelated macular degeneration (AMD). The relationships between structure and function were investigated for both standard and short-wavelength automated perimetry (SWAP). Factors known to influence the measure of visual field progression were considered, including the accuracy of the refractive correction on SWAP thresholds and the learning effect. Techniques of assessing the structure to function relationships between fundus images and the visual field were developed with computer programming and evaluated for repeatability. Drusen quantification of fundus photographs and retro-mode scanning laser ophthalmoscopic images was performed. Visual field progression was related to structural changes derived from both manual and automated methods. Principal Findings: • Visual field sensitivity declined with advancing stage of AMD. SWAP showed greater sensitivity to progressive changes than standard perimetry. • Defects were confined to the central 5°. SWAP defects occurred at similar locations but were deeper and wider than corresponding standard perimetry defects. • The central field became less uniform as severity of AMD increased. SWAP visual field indices of focal loss were of more importance when detecting early change in AMD, than indices of diffuse loss. • The decline in visual field sensitivity over stage of severity of AMD was not uniform, whereas a linear relationship was found between the automated measure of drusen area and visual field parameters. • Perimetry exhibited a stronger relationship with drusen area than other measures of visual function. • Overcorrection of the refraction for the working distance in SWAP should be avoided in subjects with insufficient accommodative facility. • The perimetric learning effect in the 10° field did not differ significantly between normal subjects and AMD patients. • Subretinal deposits appeared more numerous in retro-mode imaging than in fundus photography.

Depressive disorders are common and debilitating conditions; however, current methods of diagnosis and treatment are suboptimal, largely due to a lack of understanding of the biological basis of these disorders. Neuroimaging has provided substantial insights in this area, but one particularly understudied area is the relationship between unipolar and bipolar depression. These disorders have similar symptom profiles but require different treatment strategies, making their diagnosis and management challenging for clinicians. The overarching aim of this thesis is to understand differences and similarities in the structure and neurochemistry of neurobiological systems underlying unipolar and bipolar depression. This question is addressed in three ways: Firstly meta-analyses structural neuroimaging studies looking at alterations in grey and white matter were performed to identify patterns of changes that were common or specific to either disorder. Secondly, an original investigation was carried out to identify patterns of neurochemical alteration that differ between unmedicated patients with unipolar and bipolar depression. Lastly, the appropriateness of a dimensional approach to bipolarity in depression was evaluated by looking for structural neural correlates of bipolar symptoms within patients with unip9olar and bipolar depression. The results of these studies show that although many neurobiological alterations are common to unipolar and bipolar depression, there are changes in grey matter volume that are specific to unipolar depression, and changes in white matter volume that are specific to bipolar depression. However, alterations in grey matter volume do not correlate with bipolarity when treated as a dimensional characteristic. These results contribute to our understanding of structural and neurochemical alterations in depressive disorders, and provide targets for future research into improved diagnosis of these conditions.

Collagen plays an important role in many biological tissues, including skin, which, once dried and treated, forms parchment and leather. The structural alterations that occur in collagenous materials due to X-ray radiation damage, fluctuation of relative humidity, and mechanical deformation (with a special focus on historical parchment) are the focus of this thesis. The primary aim of this thesis is to investigate major structural changes to collagen within parchment when exposed to inappropriate levels of relative humidity during conservation treatments, and cyclic-humidity during long-term storage in archives, museums and libraries. This study led to the discovery that each parchment sample reacted to the application and removal of moisture in a different way, indicating the fundamental need to treat individual parchment documents as in-homogeneous materials. This thesis investigates the changes that fibrillar collagen undergoes and describes the creation of computational models capable of reproducing the X-ray diffraction patterns for collagen. Previous structural models have been created that sufficiently account for native collagen, however, models created as part of this thesis succeed where previous models have failed in explaining the X-ray diffraction patterns collected from damaged collagen. This study provided the opportunity to contribute towards a large-scale international collaborative project on the hugely important historical resource, the Domesday Book. X-ray diffraction was used to provide unprecedented analysis of Domesday Book samples, providing a structural survey at a molecular level. This analysis produced the conclusion that the majority of samples displayed the presence of collagen axial structure, and were generally of a degraded state as a consequence of the method used to source them the samples were scrapings from the surface, which was less intact than the bulk of the parchment.

Chemical-induced post-translational modifications (PTMs) can alter the structure of proteins, with consequences that may alter protein function, including interference with protein-protein interactions, subcellular protein compartmentalization, and disruption of cellular signaling pathways. To identify the impact of PTMs on the structure and function of protein targets in vitro and in vivo, electrophiles with known toxicity were utilized. Hydroquinone, and its thioether metabolites, cause renal proximal tubular cell necrosis and nephrocarcinogenicity in rats. The adverse effects of these chemicals are in part a result of their oxidation to 1,4-benzoquinones (BQ). Cytochrome c and caspase-7 have been studied as model proteins to identify site-specific adductions and the resulting structural and functional consequences associated with apoptosis. BQ and 2-(N-acetylcystein-S-yl)benzoquinone (NAC-BQ) preferentially bind to solvent-exposed lysine-rich regions within cytochrome c, and specific glutamic acid residues within cytochrome c are novel sites of NAC-BQ adduction. Furthermore, the microenvironment at the site of adduction governs both the initial specificity and the structure of the final adduct. Solvent accessibility and local pKa of the adducted and neighboring amino acids contribute to the selectivity of adduction. Post-adduction chemistry subsequently alters the nature of the final adduct. BQ induced PTMs in cytochrome c produce changes in the structure sufficient to inhibit its ability to initiate caspase-3 activation in native lysates, and its ability to promote Apaf-1 oligomerization into an apoptosome complex, in a purely reconstituted system.Quinone-thioether-protein adduct stability is also dependent upon physiological conditions. Adduct formation on cysteine residues under physiological conditions may be transient, whilst remaining capable of impacting cell signaling events, and of thus contributing to the toxic response elicited by these compounds. Indeed, in vitro analysis of caspase-7 revealed that cysteine residues within the protein are transiently modified with BQ, including the active site thiolate anion. In vitro and in vivo analysis of quinone-thioether adduction on caspase proteins also provided evidence that these catalytic proteins may be in vivo quinone-thioether targets, and could contribute to a mechanistic understanding of the necrotic mode of cell death initiated by quinone-thioether exposure. In summary, mass spectroscopic, molecular modeling, and biochemical approaches collectively confirm that electrophile-protein adducts produce structural changes that influence biological function. Identification of such chemical-induced PTMs on target proteins can provide critical mechanistic understanding of their role in response to environmental chemicals and the associated disease progression. Furthermore, because quinones are a well-known class of electrophilic species and the quinone moiety exits in a number of chemotherapeutic agents, identification of these PTMs will provide insight into the field of drug development and the role electrophilic drug metabolite-PTMs may play in unwanted drug-induced toxicities.

National concern over traumatic brain injury (TBI) is growing rapidly. Recent focus is on mild TBI (mTBI), which is the most prevalent injury level in both civilian and military demographics. A preeminent sequelae of mTBI is cognitive network disruption. Advanced neuroimaging of mTBI victims supports this premise, revealing alterations in activation and structure-function of excitatory and inhibitory neuronal systems, which are essential for network processing. However, clinical neuroimaging cannot resolve the cellular and molecular substrates underlying such changes. Therefore, to understand the full scope of mTBI-induced alterations it is necessary to study cortical networks on the microscopic level, where neurons form local networks that are the fundamental computational modules supporting cognition. Recently, in a well-controlled animal model of mTBI, we demonstrated in the excitatory pyramidal neuron system, isolated diffuse axonal injury (DAI), in concert with electrophysiological abnormalities in nearby intact (non-DAI) neurons. These findings were consistent with altered axon initial segment (AIS) intrinsic activity functionally associated with structural plasticity, and/or disturbances in extrinsic systems related to parvalbumin (PV)-expressing interneurons that form GABAergic synapses along the pyramidal neuron perisomatic/AIS domains. The AIS and perisomatic GABAergic synapses are domains critical for regulating neuronal activity and E-I balance. In this dissertation, we focus on the neocortical excitatory pyramidal neuron/inhibitory PV+ interneuron local network following mTBI. Our central hypothesis is that mTBI disrupts neuronal network structure and function causing imbalance of excitatory and inhibitory systems. To address this hypothesis we exploited transgenic and cre/lox mouse models of mTBI, employing approaches that couple state-of-the-art bioimaging with electrophysiology to determine the structural- functional alterations of excitatory and inhibitory systems in the neocortex.

The ubiquitin-dependent ATPase, p97, extracts ubiquitinated protein from macromolecular complexes by utilizing ATP-driven conformational changes. Consequently, p97 facilitates essential cellular quality control processes upstream of the proteasome, including endoplasmic reticulum associated degradation (ERAD) and ubiquitin fusion degradation (Ufd). Mutations in p97 are linked to an unusual muti-systemic disease (IBMPFD), involving skeletal muscle degeneration, Paget disease of bone, and fronto-temporal dementia, where the accumulation of ubiquitin-rich protein aggregates suggests impairment in p97-dependent activities. Interestingly, the accumulation of ubiquitin-rich aggregates is also well documented in common neurodegenerative diseases, such as Alzheimer Disease (AD). This thesis is focused on (i) understanding the structural and biochemical consequences of p97 mutations, and (ii) substantiating whether disruption of p97 cell biological function occurs in neurodegeneration. First, we employed a variety of biochemical and biophysical approaches to show that two p97 mutations, Arg155Pro and Ala232Glu, alter the conformational state and ATPase activity. We further demonstrated that these alterations were directly related to p97 protein aggregation in solution. Secondly, we identified p97 as a target of Caspase-6 (Casp6) proteolytic activity in AD and further demonstrated that the overexpression of a Casp6 cleaved p97 fragment compromises the ubiquitin-proteasome system (UPS). Finally, considering the role of IBMPFD-linked p97 mutations in activating caspases, we used simulation annealing modeling to provide evidence that structural defects in pathogenic p97 mutants enhanced p97 susceptibility to caspase-mediated processing. We further showed that p97 was indeed cleaved in dystrophic neurites and activated astrocytes of patients diagnosed with p97-linked fronto-temporal dementia (FTD). Collectively, this work identifies caspase-mediated cleavage of p97 as
La p97, une ATPase ubiquitine-dépendante, extrait des protéines ubiquitinées des complexes macromoléculaires en utilisant les changements conformationnels activés par l'ATP. Conséquemment, la p97 facilite les processus essentiels du contrôle-qualité cellulaire en amont du protéasome, incluant la dégradation associée au réticulum endoplasmique (ERAD) et la voie de dégradation des fusions ubiquitinées (Ufd). Les mutations dans la p97 sont liées à une maladie multisystémique inhabituelle (IBMPFD), impliquant comme effets la dégénération musculosquelettique, la maladie osseuse de Paget et la démence fronto-temporale, où l'accumulation d'aggrégats protéiques riches en ubiquitine suggère la perturbation des activités dépendantes à la p97. Il est intéressant de noter que cette accumulation d'aggrégats riches en ubiquitine est aussi bien démontrée dans les maladies neurodégénératives, telle que la maladie d'Alzheimer (MA). Cette thèse s'intéresse à (i) comprendre les conséquences structurales et biochimiques des mutations dans la p97, et (ii) confirmer si la pertubation de la fonction cellulaire biologique de la p97 s'observe dans la neurodégénération. D'abord, nous avons utilisé une variété d'approches biochimiques et biophysiques pour révéler que les deux mutations dans la p97, Arg155Pro et Ala232Glu, modifient l'état conformationnel et l'activité ATPase. Nous avons de plus démontré que ces altérations étaient directement liées à l'aggrégation protéique de la p97 en solution. Ensuite, nous avons identifié la p97 comme étant une cible de l'activité protéolytique de la Caspase-6 (Casp6) dans la MA et ainsi prouvé que la surexpression d'un fragment p97 clivé par la Casp6 compromet le système ubiquitine protéasome (UPS). Enfin, en tenant compte du rôle des mutations dans la p97 liées à l'IBMPFD dans les caspases activatrices, nous avons utilisé un modèle de simulation de l'appariement pour prouver que$

Background: Diabetes mellitus (DM) is a major metabolic disorder leading to severe long term complications including cardiomyopathy, nephropathy, retinopathy and neuropathy that are common in type 1 DM (T1DM) and type 2 DM (T2DM). Epidemiological studies have demonstrated a role of hyperglycaemia (HG) in eliciting adverse cardiac and renal outcomes including heart failure (HF), diastolic and renal dysfunction. This study investigated the effect of HG on left ventricle (LV) and kidney structural remodelling, function and underlying molecular events associated with the two organs over a period of 2 and 4 months compared to age-matched control. Methods: Molecular mechanisms underlying HG-induced remodelling changes including extracellular matrix (ECM) and myocyte apoptosis deposition, underlying cytokine induction, recapitulation of foetal genes, and transcriptional alterations that may influence the ECM and intracellular calcium [Ca2+]i handling in the LV and kidney of T1DM as well as T2DM were examined in this study. LV and kidney isolations following 2 and 4 months of the development of T1DM were used to assess the remodelling changes and underlying transforming growth factor β1 (TGFβ1) activity, gene expression profile of the ECM and calcium mediators using histological, immunohistochemical and quantitative gene expression analyses compared to age-matched Wistar control rats. Results: The results show that T1DM over 4 months can elicit severe structural and molecular changes in the LV and the kidney compared to 2 months of DM. The severity of these changes was significantly less in respective healthy age-matched control animals. The isolated ventricular cardiomyocytes from T1DM rats displayed altered cellular calcium (Ca2+) homeostasis and [Ca2+]i translating to alterations in mRNA abundance of key Ca2+ handling proteins, cardiac sarcoplasmic reticulum Ca2+ATPase 2a (SERCA2a), ryanodine receptor (RyR2), Na2+/Ca2+ exchanger, phospholamban (Plb), L-type Ca2+ channel proteins (Cav1.2 and Cav1.3), calmodulin2 (Calm2) and Ca2+/calmodulin-dependant protein kinase II delta (CaMK2d) were significantly (p < 0.05) altered in DM compared to age-matched control animals. The results showed LV and kidney remodelling in the T1DM rats with increased ECM deposition that translated into increased gene expressions of key components (collagen 1α, collagen 3α, fibronectin and elastin) and modulators i.e. MMP2 and MMP9 and their tissue inhibitor (TIMP4), connective tissue growth factor (CTGF), integrin 5α and connexin 43 (Cx43) of the ECM. Molecular derangements underlying this phenotype included increased TGFβ1 transcription and activity, recapitulation of foetal gene phenotype atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) with marked hypertrophy, underscored by caspase-3 mediated cell apoptosis. Electron microscopic analysis revealed ultrastructural alterations in LV highlighted by increased mitochondrial number and altered mitochondrial population, whereas the kidney presented with increase glomerular basement membrane thickness in T1DM compared to controls. These data clearly show that adult vs young adult, in combination with STZ-induced T1DM, can elicit severe changes to both the heart and the kidney, respectively in structural, functional and biochemical alterations. The final part of the study revealed exercise training after 2-3 months may have beneficial effects in T2DM animals compared to sedentary control rats. Ventricular myocyte and shortening were generally well preserved despite alterations in mRNA gene expression encoding a variety of cardiac muscle proteins in the exercised trained adult GK diabetic rat. LV remodelling in GK rat presented with marked hypertrophy of cardiomyocytes and increased ECM deposition that altogether translated into increased ECM components and regulators which were reversed by exercise training. Conclusions: The present results have demonstrated that T1DM, if left untreated, can lead to severe changes to both the heart and the kidney. These changes seem to occur at structural and molecular levels leading to dysfunction of the heart and kidney and the severity of the damage is enhanced over time. Data suggests that diabetic cardiomyopathy (DCM) may have possible origins in pro-fibrotic and pro-hypertrophic mechanisms. Moreover, this study demonstrates that physical exercise training continues to be one of the most valuable forms of non-pharmacological therapy in DM. Data concerning molecular signalling cascades and ECM phenotype is particularly significant as targeting features of structural remodelling may delay onset and severity of myocardial and renal complications.

Orientador: Priscila Lupino Gratão
Resumo: As plantas estão expostas a adversidades no ambiente que as circundam, como a contaminação por cádmio (Cd). Este metal pesado tem aumentado na atmosfera devido a atividades humanas. As plantas podem absorver o Cd, causando sérias alterações estruturais, fisiológicas e bioquímicas. As plantas desenvolveram sistemas de defesa complexos, incluindo mecanismos não enzimáticos e enzimáticos para evitar uma cascata de oxidação descontrolada causada pelo estresse oxidativo. Alguns elementos, como o selênio (Se), se utilizados em concentração adequadas, podem induzir uma melhora no sistema antioxidante, no crescimento e nos atributos fotossintéticos. Ainda é pouco conhecido o papel do Se nas respostas das plantas ao estresse. O objetivo deste trabalho foi obter novas informações sobre o papel do selenato e selenito no sistema de desintoxicação das plantas, incluindo a avaliação da nutrição mineral, atividade de enzimas antioxidantes e conteúdo de compostos não enzimáticos, pigmentos, alterações estruturais e o papel do Se na modulação do etileno, com o uso de mutantes hormonais como ferramenta. Nossos dados indicam que o Se é uma estratégia interessante para melhorar o metabolismo da planta sob condições normais ou estressantes. O selênio pode induzir aumento da ação do metabolismo de defesa antioxidante, provavelmente devido a alterações na sinalização do etileno. Além disso, em condições normais, o Se induz alterações estruturais nas células, o que pode contribuir para o desenvolvim... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Cadmium (Cd) contamination is a worldwide concern and one of the most severe causes of abiotic stress in plants, triggering losses in crop production and contamination risks to human health. This heavy metal increased in atmosphere due to human activities. Plants can uptake Cd, causing serious changes in structural, physiological and biochemical processes. Plants developed a complex defence systems including non-enzymatic and enzymatic mechanism to avoid oxidative stress and prevent an uncontrolled oxidation cascade. Some elements, such as selenium (Se), if used in adequate concentration, may induce an improvement in antioxidant system, growth and photosynthetic attributes. It is still unknown the mechanisms of Se in stress responses. The aim of this work was get new insights about the role of selenate and selenite-mediated detoxification strategies, including the evaluation of mineral nutrition, the activity of antioxidant enzymes and non enzymatic compounds, pigments, structural alterations and the role of Se in modulate ethylene, with the use of hormonal mutants as a tool. Our data indicates that Se is an interesting strategy to improve plant metabolism under normal or Cd stressful-condition. Selenium may induce enhancement in antioxidant defence metabolism, probably due to alterations in ethylene signalling. Moreover, under normal condition Se induce structural alterations in cells, which may contribute to plant development. Thus, the information available in this work is... (Complete abstract click electronic access below)
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Hypertension has been associated with causing deleterious effects to the cerebrovasculature, which are thought to underlie the formation of white matter lesions (WML) and predispose individuals to age related cognitive decline. In humans hypertension frequently occurs concomitantly with other vascular risk factors making it difficult to ascertain the primary mechanisms of hypertension in isolation. Animal models of hypertension have been used in an aid to establish the mechanisms of hypertension in isolation. To date the knowledge gleaned from animal models has undoubtedly provided an insight as to the role of hypertension and cerebrovasculature remodelling but, these models have limitations such as lack of genetically matched controls and the inability to control the severity of hypertension, restricting the understanding of the underlying mechanisms. All studies within this thesis used the Cyp1a1 Ren2 inducible hypertensive rat model, induced by dietary addition of Indole-3-carbinol (I3C), allowing the severity and duration of hypertension to be tightly controlled and compared to genetically matched controls. This thesis set out to address the hypothesis that sustained hypertension will lead to alterations to the structural integrity of the cerebrovasculature and white matter, which will be exacerbated with age and that hypertension will be associated with alterations to gene expression and cognitive function. Initially this thesis sought to investigate the effect of hypertension on the structural integrity of the vasculature in the Cyp1a1 Ren2 rat model. Firstly, blood pressure in the Cyp1a1 Ren2 rat model was characterised and it was found that the dietary addition of I3C, caused a sustained level of increased blood pressure in all three cohorts. Cerebrovascular alterations were found to consist of increased eNOS expression in the young brain, which progressed with increased duration of hypertension to vascular morphological alterations of decreased vessel width and a redistribution of tight junction protein claudin-5. With age, hypertensive vascular alterations consisted of increased eNOS expression and vascular density. Additionally, there was evidence that hypertension caused a vascular inflammatory response in the young and aged brain. Secondly, this thesis investigated the effect of hypertension on gene expression. Overall it was found that hypertension altered genes related to collagen growth factors, ion channels, eNOS related Map-Kinase pathway and inflammatory genes. Thirdly, this thesis sought to investigate the impact of hypertension on the overall structural integrity of the brain and white matter examining neurons, myelin, oligodendrocytes, axons and microglia, in several regions of the young and aged brain. In general, this study found that hypertension did not cause overt structural or myelin alterations in the majority of regions analysed, with only evidence of myelin alterations occurring within the subcortex of hypertensive animals from each of the young cohorts analysed. However, an adverse subcortical inflammatory response was found in hypertensive animals of the young 6-month cohort and also in hypertensive animals from the aged 4-month cohort, where the inflammatory response was not exclusive to the subcortex of hypertensive animals but also occurred in multiple white matter tracts. Lastly this thesis chose to examine the effect of hypertension on cognitive function, specifically spatial reference and working memory using the Morris water maze and found no evidence of alterations in the cognitive functions examined. Conclusions The results presented within this thesis demonstrated that hypertension in isolation leads to modest alterations to the integrity of the cerebrovasculature and white matter, with no evidence of alterations to specific cognitive functions examined, demonstrating the importance of studying hypertension in isolation. Additionally, this study highlights the initial hypertensive induced alterations to the cerebrovasculature, such as endothelial signalling, vascular structure and inflammation, providing a window for therapeutic intervention at a time point when there are minimal alterations to the overall structural integrity of the brain. Future studies in this model should concentrate on examining different severities of hypertension and also hypertension concomitantly with other vascular risk factors to try and recapitulate pathological alterations found in humans.

Traumatic Brain Injury (TBI) can be defined as an alteration in brain function or evidence of brain pathology caused by an external force. In this thesis the focus of attention is on brain diffuse axonal injury (DAI). DAI is widespread damage to axons throughout the white matter in the brain, caused by sustained acceleration and deceleration forces at the moment of injury (Adams, 1982). Is characterised by the presence of microhaemorrhages mainly in the cerebral hemispheres, corpus callosum, and brainstem. However, other regions such as the thalamus, basal ganglia and fornices are also susceptible (Adams, 1989). Diffuse damage makes the main contribution to neurological dysfunction in TBI patients and typically associated with poor prognosis (Smith and Meaney, 2000). In the absence of significant focal contusions, diffuse brain damage may be not detected on neuroimaging MRI initial scans and macroscopical brain examination. However, microscopic primary damage can be appreciated. In a first stage, primary damage, which is the direct consequence of the direct impact either by mechanical or external forces, produces tissue segmentation. Secondary damage then occurs. This includes a cascade of biological reactions which provokes cytoskeletal disorganization, protein accumulation, metabolic, hypoxic and microvascular damage, and excitotoxicity. As DAI is an evolving process, thus traumatic axonal injury (TAI) has more recently been suggested as a more appropriate term for describing diffuse axonal damage. These secondary processes can result in injury or complete disruption of critical white matter pathways between the cortex and deep grey matter structures (Buki & Povlishock, 2006). Taking into account that this disruption of white matter pathways may be causing cognitive deficits, the main hypothesis of this thesis is that white matter damage is responsible for the alterations in connectivity making the main contribution to cognitive deficits after diffuse, chronic and severe TBI. Moreover, the main objective to identify possible structural and functional connectivity alterations in the brains of patients suffering from diffuse axonal injury and to relate them with cognitive impairment by applying neuropsychological assessment and magnetic resonance imaging techniques. To investigate the connectivity alteration and their relationship with cognitive impairment after chronic TBI, we performed four studies. The first study aimed to investigate the role of white matter damage in declarative and working memory deficits after diffuse TBI focusing on the main associative fasciculi. Given that memory impairment is one of the most common deficits of patients with severe TBI, and taking into account the white matter alterations resulting from the first study, we performed this second study with the aim of assessing structural brain damage in subjects with diffuse and chronic severe TBI and to study its relationship with declarative memory impairment. The third study was the first multimodal approach study in TBI to explore the functional and structural patterns of connectivity underlying working memory impairment after severe traumatic axonal injury. And finally, in the fourth study, we wanted to take advantage of the analysis of resting state fMRI and aimed to explore abnormalities in brain activity and connectivity during the resting state in patients with chronic traumatic axonal injury and examine the relationship of these abnormalities with deficits in structural connectivity and global cognitive outcome. The general conclusion extracted from the results of the studies performed here is that, although after TAI there are clear widespread patterns of white matter damage and cortical atrophy, the results of these studies seem to suggest that long-term cognitive sequelae after diffuse TBI follows a predominant frontal pattern of alteration. Disrupted frontal white matter structural connectivity and the basal activity of the frontal lobe at rest are the main alterations explaining cognitive outcome after diffuse and chronic TBI.
INTRODUCCIÓN: El daño axonal difuso que se sufre después de un traumatismo craneoencefálico, produce alteraciones cerebrales estructurales y funcionales que se pueden visualizar y analizar mediante imágenes por resonancia magnética (IRM). Estas alteraciones pueden explicar los déficits cognitivos. OBJETIVO: Identificar las posibles alteraciones funcionales y estructurales cerebrales en pacientes con daño axonal difuso y su relación con sus déficits cognitivos mediante la aplicación de pruebas neuropsicológicas y IRM MÉTODOS/ESTUDIOS: La tesis incluye cuatro artículos de investigación en los que se combinan técnicas por tensor de difusión, resonancia magnética funcional, estudio de grosor cortical y volumetría junto con tests neuropsicológicos. La batería de test escogida incluye diferentes pruebas para la evaluación de los dominios cognitivos más frecuentemente alterados en estos pacientes: funciones ejecutivas, aprendizaje y memoria, atención y velocidad de procesamiento mental. Los pacientes incluidos en los estudios se caracterizan principalmente por ser pacientes adultos jóvenes (20-45 años) con TCE grave (GCS≤8) en estado crónico (≤2años desde el traumatismo craneo-encefálico), con evidencia de patología cerebral difusa en la IRM clínica, Los pacientes se han emparejado con un grupo control de acuerdo con las variables edad, escolaridad y dominancia manual. RESULTADOS: 1) El decremento de anisotropía fraccional (AF) en fascículos largos asociativos explica los déficits de memoria de trabajo mientras que una disrupción más local se relaciona más con déficits de memoria declarativa; 2) a pesar de una afectación general de sustancia blanca en todos los tractos cerebrales evidenciado por una reducción de AF y una reducción generalizada cortical, los déficits de memoria declarativa se explican por una alteración cortico-subcortical de sustancia blanca y por la reducción cortical en el área del precuneus; 3) La alteración de la conectividad estructural explica las alteraciones cerebrales de activación funcional y explica los déficits de memoria de trabajo; 4) El incremento de actividad funcional del lóbulo frontal en estado de reposo está asociado a un mejor rendimiento cognitivo. CONCLUSIÓN: La alteración de la conectividad estructural, especialmente la alteración de conexiones con el lóbulo frontal, junto con la alteración de la actividad funcional basal medida en estado de reposo, son las alteraciones principales causantes de las alteraciones cognitivas después de un traumatismo craneo-encefálico de carácter difuso.

Follicle stimulating hormone (FSH) acting on Sertoli cells of the testis plays important roles during reproductive development. FSH-R knockout (FORKO) mice provide a model to examine alterations in testicular and epididymal structure and function in its absence. Examination of the FORKO testis revealed a gross alteration of Sertoli cell structure indicative of a fluid imbalance. Functional parameters, such as ABP secretion were also significantly reduced in FORKO testis. Morphometry revealed quantitative reductions in seminiferous tubule size. The epididymal epithelium, appeared abnormal and morphometry revealed that epididymal tubule size was reduced in the knockout. Computer Assisted Sperm Analysis on sperm from the cauda epididymidis revealed significant alterations in parameters corresponding to sperm motility as well as sperm counts. These data suggest an important role for the FSH receptor on Sertoli cell structure and functions and on epididymal epithelial size and functions in relation to sperm motility.

An epidemiological shift towards the elderly population has occurred in traumatic brain injury (TBI). Age is believed to be one of the strongest prognostic indicators following TBI. Diffuse axonal injury (DAI), a prevalent feature of TBI, is believed to be the primary cause for much of the morbidity and mortality associated with TBI. The pathobiology associated with DAI is believed to occur in response to the primary injury in a progressive, secondary fashion. Though the injury mechanisms behind DAI have been shown to occur at numerous sites along the axon, recent work suggests that the axon initial segment (AIS) may show specific vulnerability to DAI and be the primary site of axonal pathobiogenesis. Despite its established predilection for injury, the mechanisms responsible for the pathobiology remain largely unclear – particularly with regard to the age. The current study aims to shed light on the mechanisms responsible for injury by investigating structural alterations to the AIS following DAI in young and old mice. To address this question we have used a central fluid percussion injury (cFPI) model to induce mild DAI on 22-month old aged mice and 3-month old young mice at 3-hours and 24-hours survival time. Double-labeling fluorescent immunohistochemistry was used to demonstrate colocalization of ankG, an AIS domain marker, and APP, a marker used to establish traumatic axonal injury (TAI). Qualitative-quantitative observations based on confocal microscopy demonstrated an increase in APP accumulation associated with AIS over time, post-injury. Initial segments displaying APP association consistently showed a significant overall shortening in young and aged groups at both survival times. No significant difference in AIS length was detected between AIS populations of young and aged mice. Qualitative findings, however, suggest that AIS degradation could be more profound with age, which could have implications on neuronal outcome.

Anorexia nervosa (AN) is a severe disorder, accepted to be of a multifactorial etiology. Although there is evidence for alterations in neural networks contributing to the onset, development and maintenance of AN, the knowledge of alterations of brain circuits is very limited. To this purpose, we investigated in three MRI experiments (two published, one in review) putative alterations in brain systems in a group of 20 female outpatients with AN, restrictive subtype, compared to a group at 20 female healthy controls. The first study aimed, in an exploratory manner, to find alterations in white matter tracts microstructure; important in the context of brain systems and the major shaping of white matter in adolescence, a vulnerable period for AN development (Study 1). To evaluate alterations in brain function, we aimed at targeting either alterations in a system known to present abnormal responses in AN: the reward system, but in a social context (Study 2), or brain alterations associated with a core symptom of the disorder: own-body processing alterations (Study 3). In Study 1, we looked at differences in quantitative scalar measures in white matter tracts, derived from diffusion tensor imaging techniques (DTI). There were two clusters of significant between-group differences, at the superior longitudinal fasciculus (SLF)-parietal parts and at the fimbria-fornix (FFo). The pattern of alterations was different, possibly corresponding to myelinisation deficits in SLF and more complex pathophysiological processes overlapped at the FFo. The location of differences suggested a link with body distortion or alterations in the reward associated with food. In Study 2, we evaluated between-group brain differences in the response to receiving either social acceptance (reward) or rejection (punishment). Patients showed differences in the dorsomedial prefrontal cortex during acceptance and in visual areas during rejection, interpreted as a motivational biased response for social relationships: low engagement in positive feedbacks and hyperattention to negative ones. Interaction and correlation analyses between brain activation and sensitivity to reward/punishment or the severity of the disorder suggested an aberrant modulation of reward areas -frontal opercula/anterior insula, ventral striatum- involved in responses to social acceptance and rejection, respectively. In Study 3, we evaluated alterations in body processing during the visualization of video-recorded own- and another’s body. The interest was in the self-evaluative component of body processing; to this purpose, our analyses were focused to brain activity differences within the default mode network (DMN). In regions with between-group differences, we additionally evaluated functional connectivity differences with other areas of the DMN during either at rest or the task. Medial parietal areas, at the dorsal posterior cingulated cortex (dPCC) and at the Precuneus, showed differences due either to an hyperresponse of patients to the own-body evaluation (dPCC) or a lack of a differential response in patients to the processing of another’s body (Precuneus). There was an additional increased dPCC to anterior cingulate cortex during own processing but decreased with angular gyrus during resting-state in patients. These results were interpreted as increased ruminative state during own-body processing in AN, possibly associated with body distortion, as well as a putative more tonic, task-unrelated alterations of posterior DMN regions. Moreover, there was an increased precuneus to mid temporal cortex functional connectivity during the other’s processing in patients; alterations to the other’s body were possibly related to alterations in social cognition processes. The three studies support alterations in two systems, a prefronto-parietal circuit -possibly associated with alterations in body processing- and in a reward/motivational system. The integration of these results in current research lines resulted in the presentation of a new theoretical frame for AN, linking self-body image, relation to others, and alterations in social interaction and reward responses.
La anorexia nerviosa es un trastorno grave y de etiología multifactorial. Actualmente se sabe que existen alteraciones en diversos circuitos cerebrales, que, a pesar de la reciente emergencia de técnicas como la deep brain stimulation (DBS) que pretenden modularlos, no conocemos suficiente. En la presente tesis se evaluaron alteraciones neuroestructurales y neurofuncionales en un grupo de 20 pacientes mujeres con anorexia nerviosa (AN), subtipo restrictivo, mediante técnicas de resonancia magnética (RM). En el primer estudio evaluamos diferencias en la microestructura de los tractos de sustancia blanca. Se encontraron alteraciones posiblemente relacionadas con distintas alteraciones de la microsestrutura en el fascículo longitudinal superior y en el fórnix. En el segundo estudio, y en relación con la creciente importancia de las alteraciones del sistema del refuerzo en AN, se evaluó la respuesta cerebral durante una situación experimental de aceptación o rechazo social. Se hallaron diferencias en la respuesta del área dorsomedial del córtex prefrontal y de áreas visuales. La actividad de estructuras del sistema del refuerzo como la ínsula y el núcleo estriado ventral se hallaron vinculadas a rasgos de personalidad y a la severidad del trastorno, influyendo en diferencias en la respuesta cerebral. En el tercer estudio, se pretendió evaluar las alteraciones de la percepción de la imagen corporal asociadas a un componente autoevaluativo. Se hallaron alteraciones en áreas de la red neuronal por defecto (RND), así como en su conectividad funcional durante la tarea y durante el estado de reposo. Las alteraciones se presentaron durante la autopercepción corporal, pero también en la percepción del cuerpo de otra persona. De forma integrada, los resultados de los tres estudios (dos publicados y uno en revisión) sugirieron la presencia de alteraciones funcionales y estructurales, en AN, en un sistema fronto-parietal, posiblemente asociado con la distorsión de la imagen corporal, también en áreas vinculadas a la motivación en un contexto social, así como en áreas del sistema de refuerzo. Los resultados, integrados en el marco de las líneas de investigación actuales, sirvieron para la presentación de un nuevo marco teórico que vincula la autopercepción corporal, interacción social y respuestas al refuerzo.

Schizophrenia is often a debilitating psychiatric disorder, characterised by both positive and negative symptoms, and cognitive and psychosocial impairments. The established disorder has been associated with a number of brain abnormalities, however it is at present unknown whether these brain changes occur prior to onset of schizophrenia, or in unaffected relatives with a familial vulnerability to develop the disorder, or only in those at high risk that go on to develop the disorder. Furthermore, most studies have been conducted cross-sectionally, which may have obscured subtle longitudinal changes in familial high risk individuals, and these studies tend to have focused on localized cortical gray matter , and thus it is unclear whether they affect different cortical parameters differentially. Prospective familial high risk studies utilizing surface based MRI programmes provide a good method to investigate this. In the Edinburgh High Risk Study, structural magnetic resonance imaging (MRI) scans of 150 young individuals at familial high risk of schizophrenia, 34 patients with first-episode schizophrenia and 36 matched controls were obtained. Of the high risk participants with scans suitable for analysis, 17 developed schizophrenia after the scans were taken, whilst 57 experienced isolated or sub-clinical psychotic symptoms, and 70 remained well. We used Freesurfer to extract volumetric and surface-based measurements of several cortical and localized sub-cortical regions with the aim of assessing whether any alterations found were present in all those at high risk, or selectively in the high risk cohort based on future clinical outcome, or only in those experiencing their first-episode of psychosis. It was found that those experiencing their first episode of schizophrenia exhibited significantly more widespread brain alterations compared to those at high risk or controls, both on a more global cortical level and in more localized regions of the cortex, with cortical thickness being generally thinner than in the other groups, and cortical surface area and gyrification increased compared to the other groups. An increased global surface area was also shared with the HR[ill] group, suggesting that this could be a marker that is predictive of future transition to psychosis. Within the high risk cohort, some brain alterations seemed to present as general vulnerability markers, specifically in the temporal lobe at baseline, whilst longitudinally both localized and global cortical alterations distinguished the high risk cohort from the control group, and a different developmental trajectory of the hippocampus was also found. These findings show that some brain alterations may be more accurately characterized as general vulnerability markers of the disorder, whilst some are specifically present in patients who have experienced their first episode of schizophrenia, whilst some also occur before disorder onset in those at high risk that go on to develop schizophrenia. The findings have some clinical implications, as they suggest that it is possible to assess who at high risk will go on to develop schizophrenia based on brain structural alterations. This may provide clinicians with an early window of opportunity for intervention, as it has been found that early intervention may improve patient's prognosis. The findings also have important implications for the understanding of the underlying eitology of schizophrenia, as they suggest that some of these alterations are present before illness onset, and not associated with medication effects, thus potentially lying on the causal path of developing schizophrenia.

Thesis (Ph.D.)--Indiana University, Dept. of Psychological and Brain Sciences and Program in Neuroscience, 2007.
Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 7017. Adviser: George Rebec. Title from dissertation home page (viewed May 20, 2008).

El balance del cerebro se altera a nivel estructural y funcional por el consumo de alcohol y puede causar trastornos por consumo de alcohol (TCA). El objetivo de esta Tesis Doctoral fue investigar los efectos del consumo crónico y excesivo de alcohol en el cerebro desde una perspectiva funcional y estructural, mediante análisis de imágenes multimodales de resonancia magnética (RM). Realizamos tres estudios con objetivos específicos: i) Para entender cómo las neuroadaptaciones desencadenadas por el consumo de alcohol se ven reflejadas en la conectividad cerebral funcional entre redes cerebrales, así como en la actividad cerebral, realizamos estudios en ratas msP en condiciones de control y tras un mes con acceso a alcohol. Para cada sujeto se obtuvieron las señales específicas de sus redes cerebrales tras aplicar análisis probabilístico de componentes independientes y regresión espacial a las imágenes funcionales de RM en estado de reposo (RMf-er). Después, estimamos la conectividad cerebral en estado de reposo mediante correlación parcial regularizada. Para una lectura de la actividad neuronal realizamos un experimento con imágenes de RM realzadas con manganeso. En la condición de alcohol encontramos hipoconectividades entre la red visual y las redes estriatal y sensorial; todas con incrementos en actividad. Por el contrario, hubo hiperconectividades entre tres pares de redes cerebrales: 1) red prefrontal cingulada media y red estriatal, 2) red sensorial y red parietal de asociación y 3) red motora-retroesplenial y red sensorial, siendo la red parietal de asociación la única red sin incremento de actividad. Estos resultados indican que las redes cerebrales ya se alteran desde una fase temprana de consumo continuo y prolongado de alcohol, disminuyendo el control ejecutivo y la flexibilidad comportamental. ii) Para comparar el volumen de materia gris (MG) cortical entre 34 controles sanos y 35 pacientes con dependencia al alcohol, desintoxicados y en abstinencia de 1 a 5 semanas, realizamos un análisis de morfometría basado en vóxel. Las principales estructuras cuyo volumen de MG disminuyó en los sujetos en abstinencia fueron el giro precentral (GPreC), el giro postcentral (GPostC), la corteza motora suplementaria (CMS), el giro frontal medio (GFM), el precúneo (PCUN) y el lóbulo parietal superior (LPS). Disminuciones de MG en el volumen de esas áreas pueden dar lugar a cambios en el control de los movimientos (GPreC y CMS), en el procesamiento de información táctil y propioceptiva (GPostC), personalidad, previsión (GFM), reconocimiento sensorial, entendimiento del lenguaje, orientación (PCUN) y reconocimiento de objetos a través de su forma (LPS). iii) Caracterizar estados cerebrales dinámicos en señales de RMf mediante una metodología basada en un modelo oculto de Markov (HMM en inglés)-Gaussiano en un paradigma con diseño de bloques, junto con distintas señales temporales de múltiples redes: componentes independientes y modos funcionales probabilísticos (PFMs en inglés) en 14 sujetos sanos. Cuatro condiciones experimentales formaron el paradigma de bloques: reposo, visual, motora y visual-motora. Mediante la aplicación de HMM-Gaussiano a los PFMs pudimos caracterizar cuatro estados cerebrales a partir de la actividad media de cada PFM. Los cuatro mapas espaciales obtenidos fueron llamados HMM-reposo, HMM-visual, HMM-motor y HMM-RND (red neuronal por defecto). HMM-RND apareció una vez el estado de tarea se había estabilizado. En un futuro cercano se espera obtener estados cerebrales en nuestros datos de RMf-er en ratas, para comparar dinámicamente el comportamiento de las redes cerebrales como un biomarcador de TCA. En conclusión, las técnicas de neuroimagen aplicadas en imagen de RM multimodal para estimar la conectividad cerebral en estado de reposo, la actividad cerebral y el volumen de materia gris han permitido avanzar en el entendimiento de los mecanismos homeostático
La ingesta d'alcohol altera el balanç del cervell a nivell estructural i funcional i pot causar trastorns per consum d' alcohol (TCA). L'objectiu d'aquesta Tesi Doctoral fou estudiar els efectes en el cervell del consum crònic i excessiu d'alcohol, des d'un punt de vista funcional i estructural i per mitjà d'anàlisi d'imatges de ressonància magnètica (RM). Vam realitzar tres anàlisis amb objectius específics: i) Per a entendre com les neuroadaptacions desencadenades pel consum d'alcohol es veuen reflectides en la connectivitat cerebral funcional entre xarxes cerebrals, així com en l'activitat cerebral, vam realitzar estudis en rates msP en les condicions de control i després d'un mes amb accés a alcohol. Per a cada subjecte vam obtindre els senyals de les xarxes cerebrals tras aplicar a les imatges funcionals de RM en estat de repòs una anàlisi probabilística de components independents i regressió espacial. Després, estimàrem la connectivitat cerebral en estat de repòs per mitjà de correlació parcial regularitzada. Per a una lectura de l'activitat cerebral vam adquirir imatges de RM realçades amb manganés. En la condició d'alcohol vam trobar hipoconnectivitats entre la xarxa visual i les xarxes estriatal i sensorial, totes amb increments en activitat. Al contrari, va haver-hi hiperconnectivitats entre tres parells de xarxes cerebrals: 1) xarxa prefrontal cingulada mitja i xarxa estriatal, 2) xarxa sensorial i xarxa parietal d'associació i 3) xarxa motora-retroesplenial i xarxa sensorial, sent la xarxa parietal d'associació l'única xarxa sense increment d'activitat. Aquests resultats indiquen que les xarxes cerebrals ja s'alteren des d'una fase primerenca caracteritzada per consum continu i prolongat d'alcohol, disminuint el control executiu i la flexibilitat comportamental. ii) Per a comparar el volum de MG cortical entre 34 controls sans i 35 pacients amb dependència a l'alcohol, desintoxicats i en abstinència de 1 a 5 setmanes vam emprar anàlisi de morfometria basada en vòxel. Les principals estructures on el volum de MG va disminuir en els subjectes en abstinència van ser el gir precentral (GPreC), el gir postcentral (GPostC), la corteça motora suplementària (CMS), el gir frontal mig (GFM), el precuni (PCUN) i el lòbul parietal superior (LPS). Les disminucions de MG en eixes àrees poden donar lloc a canvis en el control dels moviments (GPreC i CMS), en el processament d'informació tàctil i propioceptiva (GPostC), personalitat, previsió (GFM), reconeixement sensorial, enteniment del llenguatge, orientació (PCUN) i reconeixement d'objectes a través de la seua forma (LPS). iii) Caracterització de les dinàmiques temporals del cervell com a diferents estats cerebrals, en senyals de RMf mitjançant una metodologia basada en un model ocult de Markov (HMM en anglès)-Gaussià en imatges de RMf, junt amb dos tipus de senyals temporals de múltiples xarxes cerebrals: components independents i modes funcionals probabilístics (PFMs en anglès) en 14 subjectes sans. Quatre condicions experimentals van formar el paradigma de blocs: repòs, visual, motora i visual-motora. HMM-Gaussià aplicat als PFMs (senyals de RM funcional de xarxes cerebrals) va permetre la millor caracterització dels quatre estats cerebrals a partir de l'activitat mitjana de cada PFM. Els quatre mapes espacials obtinguts van ser anomenats HMM-repòs, HMM-visual, HMM-motor i HMM-XND (xarxa neuronal per defecte). HMM-XND va aparèixer una vegada una tasca estava estabilitzada. En un futur pròxim s'espera obtindre estats cerebrals en les nostres dades de RMf-er en rates, per a comparar dinàmicament el comportament de les xarxes cerebrals com a biomarcador de TCA. En conclusió, s'han aplicat tècniques de neuroimatge per a estimar la connectivitat cerebral en estat de repòs, l'activitat cerebral i el volum de MG, aplicades a imatges multimodals de RM i s'han obtés resultats que han permés avançar en l'enteniment dels m
Alcohol intake alters brain balance, affecting its structure and function, and it may cause Alcohol Use Disorders (AUDs). We aimed to study the effects of chronic, excessive alcohol consumption on the brain from a functional and structural point of view, via analysis of multimodal magnetic resonance (MR) images. We conducted three studies with specific aims: i) To understand how the neuroadaptations triggered by alcohol intake are reflected in between-network resting-state functional connectivity (rs-FC) and brain activity in the onset of alcohol dependence, we performed studies in msP rats in control and alcohol conditions. Group probabilistic independent component analysis (group-PICA) and spatial regression were applied to resting-state functional magnetic resonance imaging (rs-fMRI) images to obtain subject-specific time courses of seven resting-state networks (RSNs). Then, we estimated rs-FC via L2-regularized partial correlation. We performed a manganese-enhanced (MEMRI) experiment as a readout of neuronal activity. In alcohol condition, we found hypoconnectivities between the visual network (VN), and striatal (StrN) and sensory-cortex (SCN) networks, all with increased brain activity. On the contrary, hyperconnectivities were found between three pairs of RSNs: 1) medial prefrontal-cingulate (mPRN) and StrN, 2) SCN and parietal association (PAN) and 3) motor-retrosplenial (MRN) and SCN networks, being PAN the only network without brain activity rise. Interestingly, the hypoconnectivities could be explained as control to alcohol transitions from direct to indirect connectivity, whereas the hyperconnectivities reflected an indirect to an even more indirect connection. These findings indicate that RSNs are early altered by prolonged and moderate alcohol exposure, diminishing the executive control and behavioral flexibility. ii) To compare cortical gray matter (GM) volume between 34 healthy controls and 35 alcohol-dependent patients who were detoxified and remained abstinent for 1-5 weeks before MRI acquisition, we performed a voxel-based morphometry analysis. The main structures whose GM volume decreased in abstinent subjects compared to controls were precentral gyrus (PreCG), postcentral gyrus (PostCG), supplementary motor cortex (SMC), middle frontal gyrus (MFG), precuneus (PCUN) and superior parietal lobule (SPL). Decreases in GM volume in these areas may lead to changes in control of movement (PreCG and SMC), in processing tactile and proprioceptive information (PostCG), personality, insight, prevision (MFG), sensory appreciation, language understanding, orientation (PCUN) and the recognition of objects by touch and shapes (SPL). iii) To characterize dynamic brain states in functional MRI (fMRI) signals by means of an approach based on the Hidden Markov model (HMM). Several parameter configurations of HMM-Gaussian in a block-design paradigm were considered, together with different time series: independent components (ICs) and probabilistic functional modes (PFMs) on 14 healthy subjects. The block-design fMRI paradigm consisted of four experimental conditions: rest, visual, motor and visual-motor. Characterizing brain states' dynamics in fMRI data was possible applying the HMM-Gaussian approach to PFMs, with mean activity driving the states. The four spatial maps obtained were named HMM-rest, HMM-visual, HMM-motor and HMM-DMN (default mode network). HMM-DMN appeared once a task state had stabilized. The ultimate goal will be to obtain brain states in our rs-fMRI rat data, to dynamically compare the behavior of brain RSNs as a biomarker of AUD. In conclusion, neuroimaging techniques to estimate rs-FC, brain activity and GM volume can be successfully applied to multimodal MRI in the advance of the understanding of brain homeostasis in AUDs. These functional and structural alterations are a biomarker of chronic alcoholism to explain impairments in executive control, reward evaluation and visuospatial processing.
Pérez Ramírez, MÚ. (2018). Characterizing functional and structural brain alterations driven by chronic alcohol drinking: a resting-state fMRI connectivity and voxel-based morphometry analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113164
TESIS

Orientador: Wilson Nadruz Júnior
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: Pacientes hipertensos exibem aumento do risco para desenvolvimento de eventos cardiovasculares e redução da função pulmonar quando comparados com a população geral. Contudo, ainda não está claro se esta associação se origina da coexistência de doenças altamente prevalentes ou de ações diretas ou indiretas de mecanismos fisiopatológicos em comum. Este estudo investigou a associação entre características das artérias carótidas e função pulmonar em hipertensos não fumantes com função pulmonar supostamente normal. Pacientes hipertensos (n=67) foram avaliados transversalmente por análises clínicas, hemodinâmicas, laboratoriais e ultrassom de carótidas. A capacidade vital forçada (CVF), o volume expiratório forçado no primeiro segundo (VEF1) e no sexto segundo (VEF6) e a idade pulmonar foram medidos por espirometria. Os indivíduos com anormalidades ventilatórias de acordo com o consenso da American Thoracic Society/ European Respiratory Society foram excluídos. Análises bivariadas mostraram que a idade pulmonar e o percentual do previsto para parâmetros espirométricos correlacionaram-se com espessura íntima-média, diâmetro e rigidez da artéria carótida comum. Níveis séricos de Proteína C-reativa e metaloproteinases 2 e 9 não influenciaram esta relação. Na análise de regressão tipo stepwise, a idade pulmonar foi o parâmetro espirométrico que exibiu os coeficientes de regressão mais significativos com as características carotídeas. Em conclusão, o declínio da função pulmonar, particularmente quando avaliado pela idade pulmonar, está independentemente associado com alterações estruturais carotídeas em indivíduos hipertensos não fumantes com função pulmonar supostamente normal
Abstract: Hypertensive patients exhibit higher cardiovascular risk and reduced lung function compared to the general population. Whether this association stems from the coexistence of two highly prevalent diseases or from direct or indirect links of pathophysiological mechanisms is presently unclear. This study investigated the association between lung function and carotid features in non-smoking hypertensive subjects with supposed normal lung function. Hypertensive patients (n=67) were cross-sectionally evaluated by clinical, hemodynamic, laboratory and carotid ultrasound analysis. Forced vital capacity, forced expired volume in 1s and in 6s and lung age were estimated by spirometry. Subjects with ventilatory abnormalities according to current guidelines were excluded. Bivariate analysis showed that lung age and the percentage of predicted spirometric parameters correlated with common carotid intima-media thickness, diameter and stiffness. C-reactive protein and matrix-metalloproteinases-2/9 levels did not influence this relationship. At stepwise regression analyses, lung age was the spirometric parameter exhibiting the most significant regression coefficients with carotid features. In conclusion, decline in lung function, particularly when assessed by lung age, is independently associated with carotid structural alterations in non-smoking hypertensive subjects with supposed normal lung function
Mestrado
Clinica Medica
Mestra em Clínica Médica

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior
IntroduÃÃo: Hà vÃrias evidÃncias na literatura que validaram o conceito de compressÃo neurovascular (CNV) como causa principal da neuralgia trigeminal (NT) primÃria, justificando a descompressÃo vascular microcirÃrgica (DVMC) como a principal opÃÃo terapÃutica. Paralelamente, outros estudos demonstraram que o resultado em longo prazo da DVMC depende do grau de intensidade da CNV. No tocante à fisiopatologia da NT, trabalhos recentes mostraram que a CNV pode ocasionar alteraÃÃes morfolÃgicas do nervo trigÃmeo (nTRI), tais como deformaÃÃo, desmielinizaÃÃo focal e atrofia neural. Contudo, pouca informaÃÃo à conhecida sobre a real natureza da lesÃo existente nos nTRI de pacientes com NT. Objetivo: O objetivo deste trabalho foi estudar as caracterÃsticas por ressonÃncia magnÃtica (RM) de alta resoluÃÃo das CNV e as alteraÃÃes estruturais dos nTRI em pacientes com NT primÃria. MÃtodo: Nos protocolos I (RM de 1,5 Tesla [T]) e II (RM de 3,0 T), foram estudados, respectivamente, 100 e 40 pacientes, submetidos à DVMC para tratamento de NT. Todos os pacientes foram submetidos, no prÃ-operatÃrio, Ãs trÃs sequÃncias seguintes em alta resoluÃÃo: 3D T2, 3D time-of-flight (TOF) magnetic resonance angiography (MRA) e 3D T1 com injeÃÃo de GadolÃnio (T1-Gd). As imagens foram analisadas e comparadas aos achados cirÃrgicos, quanto à identificaÃÃo e caracterizaÃÃo das CNV. No protocolo III, os parÃmetros anatÃmicos, volume (V) e Ãrea seccional (AS), dos nTRI de 50 pacientes com NT e de 20 indivÃduos normais (grupo controle), foram comparados entre os nTRI afetados (grupoipsilateralNT) e nÃo-afetados (grupo contralateralNT) dos pacientes e os nTRI controles. Osresultados foram correlacionados com as caracterÃsticas dos pacientes, as caracterÃsticas dasCNV e o resultado clÃnico dois anos apÃs a DVMC. No protocolo IV, a fraÃÃo de anisotropia(FA) e o coeficiente de difusÃo aparente (CDA) de 10 pacientes com NT e de seis indivÃduos normais (controle) foram obtidos em sequÃncia diffusion tensor imaging (DTI) em aparelhode 3,0 T e comparados entre os grupos ipsilateralNT, contralateralNT e controles. Resultados: No Protocolo I, a sensibilidade e a especificidade das imagens em detectar as CNV foram, respectivamente, 96,7% (88/91) e 100% (9/9). A anÃlise das imagens identificou corretamente o vaso responsÃvel pela compressÃo em 87,9% dos casos e o grau de intensidade da compressÃo em 84,6% casos. Jà no Protocolo II, a sensibilidade e a especificidade das imagens foram, respectivamente, 97,4% (37/38) e 100% (2/2). A anÃlise das imagensidentificou corretamente o vaso responsÃvel pela compressÃo em 89,1% dos casos e o grau deintensidade da compressÃo em 83,8% dos casos. No Protocolo III, as mÃdias de V e AS dogrupo ipsilateralNT foram menores (p<0,05) do que nos grupos contralateral NT e controle. No grupo ipsilateralNT, os menores valores de V e AS foram encontrados nos nTRI, cujas CNV eram de grau III, e naqueles, cujos pacientes foram considerados curados ao final do seguimento clÃnico (p<0,05). No Protocolo IV, a FA do grupo ipsilateralNT foi menor (p<0,05) do que nos grupos contralateralNT e controle. Jà o CDA do grupo ipsilateralNT foi maior (p<0,05) do que nos grupos contralateralNT e controle. ConclusÃo: As sequÃncias 3D T2, 3D TOF-MRA e 3D T1-Gd tiveram alta sensibilidade e alta especificidade na detecÃÃo de CNV e na prediÃÃo do grau de intensidade da compressÃo. Os resultados sugerem a existÃncia de importante atrofia nos nTRI afetados pelas CNV, estando a atrofia correlacionada ao grau
Introduction: Neurovascular compression (NVC) is commonly accepted as being, in most patients, the main or most common cause of primary trigeminal neuralgia (TN), justifying microvascular decompression (MVD) as first neurosurgical option. In the same idea, other studies demonstrated that the degree of severity of NVC correlated with the long-term sucess rate after MVD. The chronic NVC may originate morphological changes in the trigeminal nerve (TGN), like nerve deviation, focal demyelination and atrophy. By contrast, little information is available about the real nature of the underlying nerve lesions of patients with TN. Objetive: The aim of this thesis was to study the characteristics by high-resolutionimaging (MRI) of NVC and structural alterations of TGN in patients with primary TN. Methods: On the First (MRI 1.5 Tesla [T]) and Second (MRI 3.0 T) Protocols, we studied, respectively, 100 and 40 patients, who underwent MVD for TN. All patients underwent a MRI with 3D T2-weighted, 3D time-of-flight (TOF) magnetic resonance angiography(MRA), and 3D T1-weighted Gadolinium-enhanced sequences in combination. Imaging analysis were performed to detect and to assess features of NVC and these data compared with the operative findings. On the Third Protocol, anatomical TGN parameters (volume, V; and cross-sectional Ãrea, CSA), obtained in 50 patients with primary TN and in 20 normal control subjects (control group), were compared between the symptomatic (ipsilateralTN group) and asymptomatic (contralateralTN group) sides of the face of patients and both sides of the control group. These data were correlated with patientâs characteristics, NVC characteristics and clinical outcomes at the 2-year follow-up after surgery. On the Fourth Protocol, the fraction of anisotropy (FA) and the apparent diffusion coefficient (ADC) ofTGN, in 10 patients with primary TN and in 6 normal control subjects, were obtained in a diffusion tensor imaging (DTI) sequencing, in a 3,0 T MRI, and compared between the ipsilateralTN, contralateralTN and control groups. Results: On the First Protocol, MRI sensitivity was 96.7% (88/91) and specificity 100% (9/9) for NVC detection. Image analysis correctly identified compressible vessel in 87.9% of cases and degree of compression in 84,6% of cases. On the Second Protocol, MRI sensitivity was 97.4% (37/38) and specificity 100% (2/2) for NVC detection. Image analysis correctly identified compressible vessel in 89.1% of cases and degree of compression in 83.8% of cases. On the Third Protocol, the mean V and CSA of the TGN on the ipsilateralTN group was significantly smaller (p<0.05) than those for the contralateralTN and control groups. On the ipsilateralTN group, the lowest values of V and CSA were found in TGN with NVC of grade III and in those of patients considered cured at 2-year of follow-up (p<0.05). On the Fourth Protocol, the FA of the ipsilateralTN group was significantly smaller (p<0.05) than those for the contralateralTN and control groups. The ADC of ipsilateralTN group was significantly higher (p<0.05) than those for the contralateralTN and control groups. Conclusion: 1.5 T or 3.0 T MRI using 3D T2- weighted in combination with 3D TOF-MRA and 3D T1-weighted Gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression. Results showed that atrophic changes, found in TGN of affected side of patients, were correlated with the severity of compression and clinical outcomes. Our work demonstrated also that DTI revealed alteration in FA and ADC values of affected TGN, and these alterations were correlated with atrophic changes in patients with TN caused by NVC.

This thesis demonstrates that geological setting, depositional facies, open system flux of hot basinal brines and descending of shallow waters have a strong impact on the distribution of the diagenetic alterations within continental and paralic/shallow marine sandstones which in turn control the quality and heterogeneities of the reservoirs. Geological setting controls the mineralogical and textural maturity of sandstone, whereas depositional facies control the pore water chemistry (marine, brackish or meteoric), sedimentary texture and sand body geometry. Eogenetic alterations in the fluvial deposits are dominated by precipitation of infiltrated clays, kaolinitization of detrital silicates, whereas the shallow marine deposits are dominated by precipitation of early calcite and kaolinite. Conversely mesogenetic alterations are dominated by clay minerals transformation, quartz overgrowths and Ferroan- carbonates, barite and anhydrite. Flux of hot basinal brines is evidenced by precipitation of mesogenetic minerals that lack of internal sources (e.g. barite, anhydrite and ferroan carbonate cements), which is evidenced by: (1) restricted occurrence of these minerals in downthrown blocks. (2) The high fluid inclusion homogenization temperatures (Th) of quartz overgrowths (Th > 110-139°C), and carbonate cements (T > 80-140°C), which also have light δ18OV-PDB(-17.6‰ to -6.7‰). Flux of hot basinal brines is further evidenced by occurrence of saddle Fe-dolomite along stylolites. Fluid inclusion microthermometry further revealed a dramatic shift in pore- water chemistry from NaCl dominated brines during precipitation of quartz overgrowths to NaCl-CaCl2 dominated brines during cementation by Fe-dolomite. Presence of mixed brine (NaCl+CaCl2) systems in the fluid inclusions suggests flux of descending waters, which have circulated in the overlying carbonate-evaporite successions. The restricted occurrence of oil- filled inclusion to quartz overgrowths and methane to Fe-carbonate cements suggest migration of oil during precipitation by quartz and migration of methane during precipitation by Fe- carbonate cements. The extensive mesogenetic cements in the down thrown blocks is attributed to flux of basinal brines along deep seated faults, i.e. open system diagenesis. Integration of fluid inclusion microthermometry, isotopes, Raman spectrometry and thermal tectonic evolution of basins are essential techniques for unraveling the evolution of basinal fluids, cementation conditions and relative timing of hydrocarbons migration.

Errata: Felaktigt disputationsdatum på spikbladet.

Stress-related cognitive changes are still a matter of debate. In some particular neuropathological conditions such as focal ischemia, cognitive functions have been shown to be significantly impaired. These conditions, however, may be improved by some factors such as steroid hormones. The purpose of the current thesis was to assess the structural and functional effects of corticosterone-related experiences on the hippocampus before and after endothelin-1 (ET-1)-induced stroke. We found corticosterone-related experiences enhance the hippocampal recovery, and improve its function in both wet and dryland tasks after ET-1-induced focal stroke. Structural and functional effects of such experiences prior to the focal ischemia in the hippocampus, however, showed that stress, not corticosterone is a strong inhibitor for hippocampal recovery.
xii, 252 leaves : ill. ; 29 cm. --

Diabetes mellitus comprises a cohort of genetic and metabolic diseases which are characterized by the hallmark symptom of hyperglycemia. Diabetic subtypes are based on their pathogenetic origins: the most prevalent subtypes are the autoimmune-mediated type 1 diabetes mellitus (T1DM) and the metabolic disease of type 2 diabetes mellitus (T2DM). Genetic factors are major contributory aspects to diabetes development, particularly in T2DM where there is close to 80% concordance rates between monozygotic twins. However, the functional state of the pancreatic β cell is of paramount importance to the development of diabetes. Perturbations that lead to β cell dysfunction impair insulin production and secretion and precede diabetes onset. The endoplasmic reticulum (ER) is a subcellular organelle network of tubes and cisternae with multifaceted roles in cellular metabolism. Alterations to ER function such as those begotten by the accumulation of misfolded and unfolded ER client proteins upset the ER homeostatic balance, leading to a condition termed ER stress. Subsequent sensing of ER stress by three ER transmembrane proteins, initiates an adaptive reaction to alleviate ER stress: this is known as the unfolded protein response (UPR). Divergent cascades of the UPR attempt to mitigate ER stress and restore ER homeostasis: Failing that, the UPR initiates pro-apoptotic pathways. The demand of insulin production on the β cell necessitates the presence of a highly functional ER. However, the consequence of dependence on the ER for insulin synthesis and secretion portends disaster for the functional state of the β cell. Disturbances to the ER that elicit ER stress and UPR activation causes β cell dysfunction and may lead to apoptosis. There are numerous well-characterized models of ER stress-mediated diabetes, including genetic mutations in UPR transducers and insulin. Recently, polymorphisms in Wolfram syndrome 1 (WFS1), an ER transmembrane protein involved in the UPR, were suggested to contribute to T2DM risk. In this thesis, one of the highlighted WFS1 polymorphism, H611R, was examined to identify its contribution to β cell function and viability, and hence, diabetes risk. It was revealed that augmentation of WFS1 expression increased insulin secretion and cellular content. In addition, WFS1 protected β cells against ER stress-mediated dysfunction, with a more pronounced effect in the WFS1-R611 protective allele. Subsequent gene expression analysis identified netrin-1 as a WFS1-induced survival factor. As a contributory factor to diabetes progression, ER stress and UPR are potential drug and biomarker targets. In this dissertation, a novel UPR-regulating microRNA (miRNA) family was uncovered in ER stressed, WFS1-deficient islets. These miRNAs, the miR-29 family, are induced in WFS1 -/- islets as a possible adaptive alteration to chronic ER stress conditions, and indirectly decreases the expression of UPR transducers, while directly targeting downstream ER stress-related pro-apoptotic factors. Collectively, this work extends the function of WFS1 as a protective factor in the pancreatic β cell through the induction of netrin-1 signaling. Additionally, it further strengthens the role of miRNA as regulatory members of the UPR which contribute to cell survival.

Major depressive disorder (MDD) is a heritable and highly debilitating condition with antidepressants, first-line treatment, demonstrating low to modest response rates. No current biological mechanism substantially explains MDD but both neurostructural and neurochemical pathways have been suggested. Further explication of these may aid in identifying subgroups of MDD that are better defined by their aetiology. Specifically, genetic stratification provides an array of tools to do this, including the intermediate phenotype approach which was applied in this thesis. This thesis explores genetic overlap with regional brain volume and MDD and the genetic and non-genetic components of antidepressant response. The first study utilised the most recent published data from ENIGMA (Enhancing Neuroimaging Genetics through Meta-analysis) Consortium's genome-wide association study (GWAS) of regional brain volume to examine shared genetic architecture between seven subcortical brain volumes and intracranial volume (ICV) and MDD. This was explored using linkage disequilibrium score regression (LDSC), polygenic risk scoring (PRS) techniques, Mendelian randomisation (MR) analysis and BUHMBOX (Breaking Up Heterogeneous Mixture Based On Cross-locus correlations). Results indicated that hippocampal volume was positively genetically correlated with MDD (rg= 0.46, P= 0.02), although this did not survive multiple comparison testing. Additionally, there was evidence for genetic subgrouping in Generation Scotland: Scottish Family Health Study (GS:SFHS) MDD cases (P=0.00281), however, this was not replicated in two other independent samples. This study does not support a shared architecture for regional brain volumes and MDD, however, provided some evidence that hippocampal volume and MDD may share genetic architecture in a subgroup of individuals, albeit the genetic correlation did not survive multiple testing correction and genetic subgroup heterogeneity was not replicated. To explore antidepressant treatment resistance, the second study utilised prescription data in (GS:SFHS) to define a measure of (a) treatment resistance (TR) and (b) stages of resistance (SR) by inferring antidepressant switching as non-response. GWAS were conducted separately for TR in GS:SFHS and the GENDEP (Genome-based Therapeutic Drugs for Depression) study and then meta-analysed (meta-analysis n=4,213, cases=358). For SR, a GWAS on GS:SFHS only was performed (n=3,452). Additionally, gene-set enrichment, polygenic risk scoring (PRS) and genetic correlation analysis were conducted. No significant locus, gene or gene-set was associated with TR or SR, however power analysis indicated that this analysis was underpowered. Pedigree-based correlations identified genetic overlap with psychological distress, schizotypy and mood disorder traits. Finally, the role of neuroticism, psychological resilience and coping styles in antidepressant resistance was investigated. Univariate, moderation and mediation models were applied using logistic regression and structural equation modelling techniques. In univariate models, neuroticism and emotion-orientated coping demonstrated significant negative association with antidepressant resistance, whereas resilience, task-orientated and avoidance-orientated coping demonstrated significant positive association. No moderation of the association between neuroticism and TR was detected and no mediating effect of coping styles was found. However, resilience was found to partially mediate the association between neuroticism and TR. Whilst the first study does not indicate a genetic overlap between regional brain volumes and MDD, it demonstrates the utility of the intermediate approach in complex disease. Antidepressant resistance was associated with neuroticism both genetically and phenotypically, indicating its role as an intermediate phenotype. Nonetheless, larger sample sizes are needed to adequately address the components of antidepressant resistance. Further work in antidepressant non-response may help to identify biological mechanisms responsible in MDD pathology and help stratify individuals into more tractable groups.

La maladie de Parkinson (MP) est une pathologie neurodégénérative caractérisée par des troubles moteurs. Cependant, des symptômes non-moteurs tels que les troubles cognitifs font partie intégrante du tableau clinique de la maladie. Trois grandes présentations cliniques des troubles cognitifs dans la MP peuvent être distinguées : (a) l’absence de troubles significatifs malgré d’éventuels symptômes, (b) les troubles cognitifs légers et (c) la démence de la maladie de Parkinson. Les troubles cognitifs légers renvoient à des déficits cognitifs significatifs en l’absence de déclin cognitif global et d’impact sur les principales activités de la vie quotidienne. Ces troubles, communs dans la maladie de Parkinson, peuvent affecter diverses fonctions cognitives. L’hypothèse du double syndrome suggère l’existence de deux sous-types cognitifs : frontostriatal, caractérisé par des déficits attentionnels et/ou exécutifs, et cortical postérieur, caractérisé par des déficits visuospatiaux, mnésiques et/ou langagiers. Ce dernier a été associé avec un risque accru d’évolution précoce vers la démence. À ce jour, peu d’études ont pris en compte l’hétérogénéité des troubles cognitifs légers observés dans la MP et aucune étude n’a déterminé des sous-types sur la base de l’hypothèse du double syndrome. Par ailleurs, nous manquons de biomarqueurs in-vivo associés à ces sous-types cognitifs.Les objectifs principaux de cette thèse étaient (a) de proposer un état de l’art concernant les résultats en neuroimagerie associés à des sous-types cognitifs distincts de troubles cognitifs légers dans la maladie de Parkinson et (b) d’identifier en IRM des changements structuraux et fonctionnels du cerveau associés aux sous-types frontostriatal et cortical postérieur.Par conséquent, nous avons réalisé une revue systématique qui a montré un manque dans la littérature scientifique étant donné que seules dix études de neuroimagerie considérant des sous-types de troubles cognitifs légers dans la maladie de Parkinson ont été identifiées. Par la suite, nous avons conduit deux études en IRM pour identifier des modifications structurales et fonctionnelles de repos dans des sous-types cognitifs de troubles cognitifs légers. Nous avons utilisé les données issues d’un groupe de patients non-déments présentant une maladie de Parkinson (n=114) dont le sous-type cognitif a été déterminé sur la base de leurs performances à une batterie de tests neuropsychologiques : (a) avec une cognition normale (PD-NC) (n=41), (b) avec un sous-type frontostriatal (PD-FS) (n=16), (c) avec un sous-type cortical postérieur (PD-PC) (n=25) et (d) avec un sous-type mixte (PD-MS), c’est-à-dire une combinaison de déficits frontostriataux et corticaux postérieurs (n=32). Pour les analyses fonctionnelles, des données issues de 24 sujets sains appariés en âge ont également été utilisées.Nos résultats ont montré (a) des altérations structurales plus abondantes et plus étendues chez les patients avec des déficits corticaux postérieurs (PD-PC et PD-MS), (b) une augmentation de la connectivité fonctionnelle au sein des ganglions de la base chez les patients PD-PC et (c) une diminution de la connectivité fonctionnelle dans divers réseaux de repos chez les patients avec des déficits frontostriataux (PD-FS et PD-MS). De futures études longitudinales seront nécessaires pour évaluer la progression de ces modifications structurales et fonctionnelles et pour déterminer le potentiel prédictif de ces marqueurs au regard du risque d’évoluer vers la démence
Parkinson’s disease (PD) is a neurodegenerative disease characterized by motor disorders. However, non-motor symptoms, including cognitive impairment, are also part of the clinical presentation. According to the severity of cognitive impairment, three presentations are usually distinguished in PD: (a) the absence of significant cognitive impairment despite possible symptoms, (b) mild cognitive impairment (MCI) and (c) PD dementia. MCI refers to significant cognitive deficits without global cognitive decline nor impact on activities of daily living. This condition is common in Parkinson’s disease (PD-MCI), can affect one or several cognitive functions and is heterogenous. According to the dual syndrome hypothesis, PD-MCI can be subdivided into two cognitive subtypes: a frontostriatal one, characterized by attentional and/or executive deficits, and a posterior cortical one, characterized by visuospatial, memory and/or language deficits. The latter has been associated with a higher risk of developing dementia earlier. To date, only few studies have considered the cognitive heterogeneity in PD-MCI and no study defined PD-MCI subtypes based on the dual syndrome hypothesis. Besides, in-vivo biomarkers of these cognitive subtypes are lacking.The main objectives of this thesis were (a) to propose a state-of-the-art on neuroimaging outcomes associated with distinct PD-MCI cognitive subtypes, and (b) to identify structural and functional MRI brain changes associated with the frontostriatal and posterior cortical subtypes.Therefore, we performed a systematic review which showed a gap in the scientific literature given that only ten neuroimaging studies considering PD-MCI subtypes were identified. Thereafter, we conducted two studies to identify structural and resting-state functional MRI modifications in PD-MCI subtypes. We used data from non-demented PD patients (n=114) whose cognitive subtype was determined by their cognitive performance at a comprehensive neuropsychological test battery: (a) patients with normal cognition (PD-NC) (n=41), (b) patients with a frontostriatal subtype (PD-FS) (n=16), (c) patients with a posterior cortical subtype (PD-PC) (n=25) and (d) patients with a mixed subtype (PD-MS) (i.e. combination of frontostriatal and posterior cortical deficits) (n=32). For functional analyses, data from 24 age-matched healthy controls were also used.Our results showed (a) more abundant and more extensive structural alterations in patients with posterior cortical deficits (PD-PC and PD-MS), (b) increased functional connectivity within the basal ganglia in PD-PC patients and (c) decreased functional connectivity in various resting-state networks in patients with frontostriatal deficits (PD-FS and PD-MS). Further longitudinal studies are needed to assess the progression of these structural and functional modifications and to determine the predictive potential of these markers regarding the risk of developing dementia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The use of direct seeding system brought changes on the weed management, by the mean of increasing of chemical control. The intense use of herbicides may have effect over the ecology of non-target soil organism. Two studies were conduct aiming testing the effect of herbicides over composition of soil mesofauna under genetically modified glyphosate resistance soy (RR®) (Chapter I) and assess the cito- genotoxicity effect of glyphosate, ammonium gluphosinate, paraquat and saflufenacil herbicide, applied during non-selective operation spray, before soy seeding (Chapter II). In Chapter I, results showed that in both agricultural years, soil mesofauna was dominate by Acari followed by Collembola, were Oribatida and Entomobryomorpha were the most predominating, respectively. In Chapter I, results showed of ammonium glufosinate favored an increase of springtails (Entomobryomorpha) and mites (Eupodes sp. Scheloribates sp. Galumnidae and Mesostigmata). Paraquat favored springtails (Entomobryomorpha) and mites (Pygmephoridae, Scheloribates sp. and Mesostigmata). Mite population (Pygmephoridae and Scheloribates sp.) increase with glyphosate treatment; and mites (Scheloribates sp.) with saflufenacil application; while in the glyphosate with saflufenacil association there was an increased springtails (Entomobryomorpha) density. The Haplotaxida Order show a greater sensitivity to glufosinato herbicides, paraquat and saflufenacil. In Chapter II, results showed that the glyphosate commercial formulation and analytical standard did not show cytotoxic effect at 5, 10 or 26ppm concentrations over the A. cepa cells; and only commercial formulation presented genotoxic. The gluphosinate shows no cytotoxic action, but tested plant cells, evidenced little genotoxic effect. Paraquat commercial formulation reduced cell division at the test concentrations (2, 4 and 11ppm) without genotoxic evidence. Saflufenacil did not affect cell division and express a weak genotoxicity using 0,25ppm concentration in plant cells test.
Com a introdução do sistema de plantio direto ocorreram mudanças no manejo de plantas daninhas, onde se intensificou o controle químico. O uso intenso de herbicidas pode ter efeito na ecologia de organismos não alvo presentes no solo. Nesse sentido foram conduzidos dois trabalhos objetivando avaliar o efeito de herbicidas sobre a composição da mesofauna edáfica em soja geneticamente modificada e resistência ao herbicida glifosato (soja RR®) (Capítulo I) e verificar o efeito citotóxico e de genotoxicidade de diferentes concentrações dos herbicidas glifosato, glufosinato, paraquat e saflufenacil, aplicados na operação de dessecação em pré-semeadura da soja RR® (Capítulo II). No capítulo I, os resultados mostraram que glufosinato favoreceu o aumento de colêmbolos (Entomobryomorpha) e ácaros (Eupodes sp. e Scheloribates sp. predadores Galumnidae e Mesostigmata). Paraquat favoreceu o aumento de colêmbolos (Entomobryomorpha) e ácaros (Pygmephoridae, Scheloribates sp. e Mesostigmata). A população dos ácaros (Pygmephoridae e Scheloribates sp.) aumentou com o tratamento glifosato; e dos ácaros (Scheloribates sp) com a aplicação de saflufenacil. Enquanto que na associação de glifosato com saflufenacil houve aumento da densidade de colêmbolos (Entomobryomorpha). A Ordem Haplotaxida apresentou maior sensibilidade aos herbicidas glufosinato, paraquat e saflufenacil. No capítulo II, os resultados mostraram que a formulação comercial e o padrão analítico do glifosato não apresentaram efeito citotóxico nas concentrações de 5, 10 ou 26ppm em células de Allium cepa; e apenas a formulação comercial apresentou ação genotóxica. O glufosinato não apresentou ação citotóxica, porém em células da planta teste se evidenciou pouca ação genotóxica. A formulação comercial de paraquat reduziu a divisão celular nas concentrações testadas (2, 4 e 11ppm), sem evidências de ação genotóxica. Saflufenacil não afetou a divisão celular e apresentou baixa ação genotóxica na concentração de 0,25ppm em células da planta teste.

Particulate matter (PM) as an important part of ambient air pollution has been associated with increased risks of cardiovascular diseases. Fibrin clot structure alteration is an emerging risk factor of many cardiovascular diseases, especially thrombosis. Therefore, the aim of this study was to investigate whether and how air particulate matter affects fibrin clot structure and endothelial cell behaviour. Turbidity assay, turbidity lysis assay and laser scanning confocal microscopy were used to analyse clots formed from normal pooled plasma or purified fibrinogen, in the presence of varying concentrations of PM. It was found that clots formed from plasma with higher concentrations of particles led to prolonged lysis time compared to control. No differences were seen for clots formed from fibrinogen. In a study of clots formed from plasma samples collected as part of a previous study on the effects of air pollution on deep vein thrombosis (DVT), alterations were observed in clots formed from plasma of DVT patients exposed to high levels of PM compared to those exposed to low levels, but the same differences were not observed in clots formed from plasma of control subjects. To investigate the potential role of venous endothelial cells in moderating clot structure following exposure to PM, human umbilical vein endothelial cells (HUVEC) were treated with PM for 24 hours and clots subsequently formed on the cells. Clots formed from plasma on the treated cells were altered compared to controls. RT-PCR and ELISA results showed increased gene expression of tissue factor (TF), protein expression of von Willebrand Factor (VWF) and plasminogen activation inhibitor-1 (PAI-1) and decreased thrombomodulin mRNA expression which were consistent with changes observed in clot structure. Engineered SiO2 nanoparticles caused denser clot structure in clots formed from normal pooled plasma. The gene expression of thrombomodulin was inhibited by SiO2 nanoparticles, but there were no significant difference in the TF mRNA expression between control and treated cells. Silica NPs caused increased concentrations of VWF, but not PAI-1 produced by endothelial cells. The results presented here show that PM can induce changes to clot structure and function, and that changes in gene expression induced in endothelial cells may be a mechanism by which a prothrombotic state is induced in response to PM exposure. Furthermore, some, but not all, similar changes were observed in clots and cells exposed to SiO2 nanoparticles, raising the possibility that such engineered nanoparticles may also have the potential to contribute to cardiovascular toxicity.

This thesis follows and analyses what happens to individuals who work at establishments that are closed down. I examine if and when the displaced workers are re-employed. Furthermore, I examine to what extent individuals have moved, changed industry of work, have started to commute or have become self-employed. Additionally I examine, if the workers become selfemployed after displacement, how many of them that does so within the same industry of work as they initially got displaced from. A unique longitudinal matched employer-employee data incorporating all firms, establishments and their employees in Sweden between the years 1997-2008 is used. All individuals between 25 and 55 years of age at the time of displacement that were displaced between 2000 and 2003 due to establishment closures are followed over a five-year period of time. Consistent with previous empirical research, it is shown that an absolute majority of the workers that are displaced one given year also recovers within that same year. The results moreover express that the longer the displaced workers are out of employment, the larger is the willingness to change industry of work, change municipality of living or move into self-employment. The willingness to commute is however found to be fairly constant over time. Finally, I find that those who become self-employed to a greater extent start business in other industries than they were displaced from as time passes.

Nous presentons dans cette etude les resultats de l'analyse moleculaire de deux genes directement impliques dans la regulation transcriptionnelle des cellules hematopoietiques, le gene du recepteur pour l'acide retinoique alpha (rar alpha), et le gene p53. Le premier est l'un des recepteurs nucleaires pour l'acide retinoique (ar), une molecule capable d'induire la differenciation cellulaire des leucemies aigues promyelocytaires (lap) in vitro et in vivo; le second, code pour un facteur transcriptionnel responsable du controle negatif de la proliferation cellulaire. Nos travaux ont permis d'evaluer le lien entre les reponses de differenciation mediees par l'ar, l'alteration structurale de son recepteur, specifiquement associee a cette pathologie et leucemogenese. La translocation t (15;17) (q22; q11-21) provoque le remaniement d'un allele du gene rar alpha qui donne naissance a des produits d'expression anormaux, observes dans la quasi-totalite des cas de lap. Le traitement par son ligand, aux doses pharmacologiques utilisees in vitro et in vivo, semble capable de restaurer une modulation positive de l'expression de l'allele normal residuel. Ceci pourrait contribuer a expliquer l'effet therapeutique exerce par l'ar et son action au niveau de la differenciation cellulaire. Nous avons aussi analyse la structure du gene onco-suppresseur p53 dans un vaste spectre de tumeurs lymphoides. Nous demontrons que les lesions de p53, frequentes dans les differents types de tumeurs epitheliales, sont par contre restreintes a certains sous-types de pathologie lymphoproliferative, notamment le lymphome de burkitt. L'incidence des mutations de p53 (sensiblement plus elevee dans les cas des lymphomes de burkitt se developpant dans le contexte de l'infection par hiv (human immunodeficiency virus). L'association preferentielle entre les alterations du gene p53 et de l'oncogene c-myc, egalement retrouvees dans ce type de lymphome, semble caracteriser d'une facon specifique la pathogenese moleculaire des lnh de type burkitt

Tourette Syndrome (TS) is a developmental neurological disorder characterised by vocal and motor tics and is associated with cortical-striatal-thalamic-cortical circuit dysfunction and hyper-excitability within cortical motor areas. TS symptoms often become more controlled throughout adolescence until the individual is largely tic-free by early adulthood. It is likely that adaptive changes occur in the development of brain structure and function throughout the critical developmental period of adolescence in people with TS, which leads to tic remission in some individuals. To investigate this I used multiple brain-imaging approaches including diffusion tensor imaging to look at white matter microstructure, T1-weighted anatomical MR imaging to measure cortical grey matter thickness and MR-Spectroscopy (MRS) to measure neurotransmitters of interest (GABA and glutamate) in a group of young people with TS and a typically developing matched control group. Brain function (measures of excitation and inhibition in M1) was also considered by using transcranial magnetic stimulation. A significant positive relationship was found between white matter structural integrity (FA) measured from the body of the corpus callosum that contained projections to M1 or the SMA and motor tic severity. The TS group had increased levels of GABA in the SMA, as measured by MRS, compared to the control group. SMA- GABA levels had a significant positive relationship with FA from the SMA ROI but a negative relationship with TMS measures of cortical excitability during movement preparation. This suggests that those individuals with the least severe tic symptoms also have reduced callosal white matter from the SMA (an area implicated in the production and suppression of tics) in adolescents with TS, which relates to a reduction in task based cortical excitability and a reduction in SMA-GABA compared to those with more severe tics. The results from this thesis suggest that tic-suppression may occur through decreasing excitatory inputs to M1, either through increasing the inhibition (GABA levels) of the SMA, or by decreasing the number of excitatory interhemispheric inputs to sensorimotor regions.