Thesis (Ph. D.)--Cornell University, August, 2008. / Vita. Includes bibliographical references (leaves 126-141).

Thesis (M.Sc. (Anatomy)) -- Mahidol University, 1976.

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 99-114).

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 95-104).

Orientadores: Fernando Cendes, Elba Cristina Sa de Camargo Etchebehere / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T16:14:13Z (GMT). No. of bitstreams: 1 Amorim_BarbaraJuarez_D.pdf: 19998647 bytes, checksum: 077344d8015d725dd9cde43d2987f38d (MD5) Previous issue date: 2007 / Resumo: O statistical parametric mapping (SPM) é uma ferramenta de quantificação que tem sido usada no SPECT de perfusão cerebral (SPECT), mas apenas poucos trabalhos na literatura comparam a sua sensibilidade com a da análise visual em pacientes com epilepsia de lobo temporal (ELT) OBJETIVO: Avaliar a capacidade da análise com SPM no SPECT em detectar o foco epileptogênico e alterações perfusionais em regiões extra-temporais em pacientes com epilepsia de lobo temporal mesial (ELTM), comparando os seus achados com os da análise visual MÉTODOS: Foram realizados SPECTs ictal e interictal em 22 pacientes com ELTM refratários ao tratamento clínico. O lado do foco epileptogênico foi definido com base na história clínica, ressonância magnética, eletroencefaiogramas seriados e telemetria. Os SPECTs foram submetidos à análise visual sendo que os SPECTs interictal e ictal foram analisados em conjunto pelos observadores (SPECT-visual-inter e SPECT-visual-ictal). Foi aplicado o SPM2 que comparou os pacientes com um grupo controle de 50 indivíduos normais. No SPM foram realizadas as seguintes comparações: grupo de SPECT interictal com o grupo controle (SPM-grupo-inter); SPECT interictal de cada paciente com o grupo controle (SPM-indiv-inter); grupo de SPECT ictal com o grupo controle (SPM-grupo-ictal); SPECT ictal de cada paciente com o grupo controle (SPM-indiv-ictal). Foram também comparadas as intensidades das alterações perfusionais nos lobos temporais procurando-se por um aumento da perfusão no SPECT ictal em relação ao interictal (SPM-indiv-ictal/inter). RESULTADOS: Não foi observada nenhuma alteração perfusional significativa no SPM-grupo-inter Já no SPM-grupo-ictal o foco epileptogênico foi a região de hiperperfusão mais significativa No SPM-indiv-inter a sensibilidade na localização do foco foi de 45% e no SPM-indiv-ictal a sensibilidade foi de 64%. O SPM-indiv-ictal/inter apresentou a maior sensibilidade para detectar o foco dentre as análises realizadas no SPM (77%) A sensibilidade do SPECT-visual-inter foi de 68% e para o SPECT-visuai-ictal foi de 100%. Por outro lado, diversas áreas de hiperperfusão e hipoperfusão à distância no SPECT ictal foram detectadas principalmente com o SPM CONCLUSÃO: O SPM é uma ferramenta que não depende do operador e é capaz de demonstrar mais áreas de alteração perfusional à distância do foco epileptogênico do que a análise visual. Ele pode ajudar a entender melhor a patofisiologia das crises epilépticas em pacientes com ELTM estudando a relação das diferentes regiões corticais e subcorticais na gênese e na propagação das crises parciais. Entretanto, essa ferramenta não acrescentou um aumento na sensibilidade na localização do foco epileptogênico em relação á análise visual, tanto do SPECT interictal quanto do SPECT ictal / Abstract: Statistical parametric mapping (SPM) is a quantitative tool which has been used in the brain perfusion SPECT (SPECT) However, few works in literature compare its sensitivity with the visual analysis in patients with temporal lobe epilepsy (TLE). PURPOSE: To investigate the capability of SPM analysis in SPECT to detect the epileptogenic focus and distant perfusion abnormalities in patients with mesial temporal lobe epilepsy (MTLE) and to compare these findings to the visual analysis. METHODS: Interictal and ictal SPECTs of 22 patients with refractory MTLE were performed. Epileptic foci were determined based on clinical history, magnetic resonance, electroencephalograms (EEG) and ictal video-EEG. SPECTs were submitted to visual analysis. Ictal and interictal SPECTs were analyzed together by the nuclear physicians (SPECT-visual-inter and SPECT-visual-ictal). It was also performed the SPM2 analysis which used a control group composed of 50 volunteers. The following comparisons were performed in SPM: interictal SPECT group with control group (SPM-group-inter); interictal SPECT from each patient with control group (SPM-indiv-inter); ictal SPECT group with control group (SPM-group-ictal), ictal SPECT from each patient with control group (SPM-indiv-ictal). It was also compared the perfusion intensity in temporal lobes looking for an increase in perfusion on ictal SPECT in relation to interictal SPECT (SPM-indiv-ictal/inter). RESULTS: No significant perfusion alterations were observed on SPM-group-inter. On the other hand, the epileptogenic temporal lobe was the region with most significant hypoperfusion on SPM-group-ictal. The sensitivity to localize the focus on SPM-indiv-inter was 45% and on SPM-indiv-ictal was 64%. The SPM-indiv ictal/inter revealed the highest sensitivity among the SPM analysis to detect the focus (77%). The sensitivity of SPECT-visual-inter was 68% and to SPECT-visual-ictal was 100%. On the other hand, several areas of distant hypoperfusion and hypoperfusion were detected mainly with SPM. CONCLUSION: SPM is a tool which does not depend on the operator and can detect more distant perfusion abnormalities than the visual analysis. It can improve the understanding of pathophysiology in seizures of patients with MTLE by studying the relation among different cortical and subcortical areas in the genesis and propagation of partial seizures. However, this tool did not increase the visual analysis sensitivity to localize the epileptogenic focus in interictal SPECT as well as in ictal SPECT / Doutorado / Neurologia / Doutor em Ciências Médicas

M.A. / Himmehoch (1984, 1987) in discussion of major mood disorders related to epilepsy, describes an affective condition termed subictal mood disorder. Patients with subictal mood disorder are divided into manic-depressive and dysthymic subtypes, the former resembling an atypical, usually rapid-cycling bipolar mood disorder. The latter dysthymic group, are characterised by a baseline dysthymia, severe recurrent depressive episodes, and transient euphorias. In addition, these dysthymic patients are described as being especially prone to impulsive suicide attempts, extreme irritability, rage outbursts and deliberate self-harm. Himmelhoch (1984, 1987) postulates temporolimbic dysfunction with both ictal and subictal (subclinical) changes as the underlying aetiology. Temporolimbic phenomena such as anamnesic, dissociative and perceptive distortions are important aspects of neuropsychiatric phenomenology. Clinical evidence, however, suggests that these occurrences are not routinely sought for or uncovered during the clinical evaluation of patients and their relevance for atypical affective presentations not clearly understood. The aim of this clinical survey was to evaluate the presence and nature of both temporolimbic dysfunction and subictal mood disorder among a subpopulation of private psychiatric patients. Furthermore in order to explicate a possible association between the above, the electroencephalographic records of these patients were examined. Records of 761 patients who attended a private practice over a two-year period were retrospectively reviewed. 546 patients had been questioned in sufficient detail and were deemed reliable in their responses. Of the 546 patients reviewed 128 (23,4%) were found to have experienced significant temporolimbic phenomena. The most common features were dissociative states, deja vu, premonitions, jamais vu and tactile hallucinations. 150 (27,5%) patients met Himmelhoch's criteria for the presence of subictal mood disorder. Of those 150, 100 (66,7%) demonstrated significant temporolimbic phenomena. EEG results, with the exclusion of 16 patients (the appropriate records not being available), highlighted 64 iY (76,2%) ofthe probands as having met the criteria for significant temporolimbic phenomena and subictal mood disorder and demonstrating unequivocal abnormality onEEG. Taking into account the sample bias of this particular private practice, and the obvious flaws of a retrospective, naturalistic survey of this nature, the concept of sub ictal mood disorder is discussed. Case vignettes are used to illustrate the phenomenological presentation ofthese patients and the potential benefits of the addition of anticonvulsants in their management.

In theoretical part, this master´s thesis deals with vibrations in cutting machine and description of creation of self-excited vibrations theory. In practical part, there is problem of chatter in cutting machine solved with using simulation program Adams and computing program MATLAB. Gradually, Multi body system of cutting machine and model of cutting tool with features flexible body are analyzed. At the end all both models were used to create complex model of the cutting machine .

No description available.

Exercise is emerging as a promising low-cost intervention to mitigate age-related memory decline and promote successful aging. Aerobic exercise training enhances cardiorespiratory fitness (CRF) and improves integrity of the medial temporal lobe (MTL) memory system. The hippocampus, a brain region located within the MTL, is critically involved in episodic and spatial memory formation, including spatial navigation, and demonstrates subfield-specific plasticity in response to aerobic exercise among both animals and young adult humans. Yet it remains unclear whether hippocampal subfield-specific exercise training and CRF effects also extend to older adults. Another modulator of structural and functional integrity of the MTL is chronic stress. Importantly, chronic stress was shown to predominantly impact brain regions such as the hippocampus and associated cognitive functions, including episodic memory, that are highly vulnerable to the effects of chronic stress and decline with age. Allostatic load (AL), or the integrative biological dysregulation of multiple biological systems resulting from chronic stress, is associated with poorer cognition, and reduced structural brain integrity. Black Americans were shown to have high burden of AL compared to non-Hispanic White Americans, and this was associated with reports of greater perceived discrimination, a salient psychosocial stressor, among the former group. Although race is a sociocultural construct, Black-White disparities exist in cognitive task performance, and risk of Alzheimer’s disease (AD) and dementia, with Black Americans displaying significantly worse cognitive task performance scores, and a greater likelihood to be diagnosed with AD and dementia compared to non-Hispanic White Americans. Thus, greater AL and discriminatory experiences in Black compared to non-Hispanic White older adults may underlie the racial disparity in neurocognitive aging. The goal of this dissertation was to examine the opposing impact of chronic stress and exercise on neurocognitive aging. This was accomplished by 1) investigating aerobic exercise intervention effects on hippocampal subfield volume and fMRI activity during spatial navigation, a complex cognitive function that declines with age and that is, in part, supported by the MTL (Project 1), 2) examining the effect of AL as a cumulative, physiological stress measure on neurocognitive aging (Project 2), and 3) examining the effect of chronic psychosocial stress through the lens of social discrimination on the functional connectivity of the MTL subsystem of the default mode network, a resting state network that has been linked to episodic memory (Project 3). The secondary aim of this dissertation was to look at the effect of AL (Project 2) and social discrimination (Project 3) on racial neurocognitive disparities in cognitively intact older Black and non-Hispanic White adults. In the first project, data from two randomized controlled clinical trials of aerobic exercise intervention targeting healthy, initially sedentary adults aged 55-85 years were used to examine the effect of exercise training and exercise-related CRF on the hippocampal integrity on the subfield level. Both randomized controlled trials randomly assigned participants to either: aerobic exercise group or active control group and underwent baseline and end-of-study fitness testing, cognitive testing, and high resolution structural and functional MRI. The first objective of this project aimed to test whether aerobic exercise training increases CRF level, which, in turn, increases anterior hippocampal subfield volume and/or attenuates volumetric decline among older adults undergoing aerobic exercise training compared to those in the active control group. Partially supporting our prediction, results displayed that following the period of the 12-week exercise intervention, the active control group but not the aerobic exercise group showed a right dentate gyrus (DG) head volumetric decline that was trending toward statistical significance. Additionally, a positive significant association between changes in CRF and left subiculum (SUB) head volume following the exercise intervention among women was found. The second objective sought to examine whether aerobic exercise intervention modulates the activation in the hippocampus in a subfield-specific manner during virtual reality navigation task performance, particularly modulating activation in the SUB subfield. Consistent with our structural results an increase in CRF was associated with a decrease fMRI activity in the left SUB. Whole-brain analysis during virtual reality navigation task performance showed that an increase in CRF was associated with a decrease in fMRI activity in the cuneus and right middle frontal gyrus, both brain regions that repeatedly display activation during virtual navigation. In the second project, existing data from the Framingham Heart Study (FHS) was used. Cognitively intact men and women, who identified as either Black or African American from the first multiracial Omni group 1 cohort (OMNI1), or White non-Hispanic from the second-generation cohort (Gen2), and were native English speakers, were included in the study. AL was calculated using the values for 10 biomarkers available in the FHS database for the two cohorts studied that are biomarkers for immune, metabolic, and cardiovascular system function. The objective of this project sought to test the prediction that AL correlates with cognitive function and brain structures, particularly hippocampal volume. We additionally sought to examine the secondary prediction that AL mediates the relationship between race and cognitive task performance and structural brain integrity, in age- sex- and education matched racial groups of cognitively intact older adults after controlling for quality of education, cardiovascular-related comorbidities and depression in the FHS cohorts. Results demonstrated that there was no significant correlation between AL and cognitive and brain volumetric measures, however there were significant Black-White disparities in cognitive task performance in verbal and visual learning and memory, abstract reasoning and attention span. These Black-White cognitive task performance disparities existed even after controlling for quality of education, and cardiovascular-related comorbidities. Although there was no significant racial disparity in the mean score of AL index, our physiological stress measure, AL partially explained the observed Black-White disparity in cognitive task performance in verbal learning and memory. Importantly the observed AL effect was not driven by the cardio-metabolic component biomarkers that are part of the AL index, known to overlap with cardiovascular risk factors, but rather, the AL index drove this effect as a whole. There were no racial disparities in brain volumetric measures after controlling for cardiovascular-related comorbidities. Furthermore, there were no sex differences in the effect of AL in any of our neurocognitive outcome measures. In the third project, cognitively intact older Black and White adults (aged 55-80 years) were recruited from the greater Boston area. To measure perceived social discrimination, participants were asked to complete the Experiences of Discrimination questionnaires. Additionally, participants underwent fMRI scanning to examine the functional connectivity of resting-state brain networks. This project sought to test the prediction that greater perceived everyday discrimination would be associated with alteration of resting state functional connectivity, particularly in the MTL subsystem. Results showed that greater perceived everyday discrimination predicted stronger resting-state connectivity between the MTL subsystem, and a cluster located in the right control network, suggesting that perceived discrimination, a psychosocial stressor, may cause functional alteration in brain networks supporting memory and cognitive control in older adults. In conclusion, findings of these studies suggest a neuroprotective effect of exercise, where exercise may attenuate aging-related decline in the structure and function of hippocampal subfields, especially among women, and possibly by targeting the SUB. Furthermore, findings of these studies suggest stress related mechanisms underlying neurocognitive integrity, particularly in the MTL memory system.

No description available.