INTRODUÇÃO: A morte encefálica (ME) associa-se à instabilidade hemodinâmica, disfunção microvascular e inflamação, comprometendo a viabilidade dos órgãos para o transplante. O hormônio 17beta-estradiol caracteriza-se por seus efeitos protetores vasculares e propriedades antiinflamatórias. OBJETIVO: Neste estudo investigou-se os efeitos do 17beta- estradiol, como modulador da microcirculação, em modelo de indução rápida de morte encefálica em ratos machos. MÉTODOS: Ratos Wistar machos foram submetidos à indução rápida de morte encefálica através da insuflação intracraniana do cateter de Fogarty. Os animais foram randomizados em 3 grupos: ratos falso-operados, apenas trepanados (FO, n=11); ratos submetidos à ME (ME, n=11); ratos tratados com 17beta-estradiol (280 ug/Kg, iv) 60 minutos após a indução da ME (E2, n=11). Os experimentos foram realizados decorridos 180 minutos após a ME. A perfusão e o fluxo sanguíneo na microcirculação mesentérica foram avaliados através das técnicas de microscopia intravital e fluxometria a laser. A expressão gênica relativa da sintase endotelial do óxido nítrico (eNOS) e da endotelina-1, no mesentério e pulmão, foi avaliada por técnica de PCR (polymerase chain reaction) em tempo real. A expressão proteica de eNOS, endotelina-1, P-selectina, molécula de adesão intercelular (ICAM)-1, molécula de adesão vascular (VCAM)-1 e molécula de adesão da plaqueta/célula endotelial (PECAM)-1 foi determinada por técnica de imunohistoquímica. As alterações histopatológicas pulmonares foram analisadas por técnica histomorfométrica. A expressão da sintase induzível do óxido nítrico (iNOS) no pulmão foi determinada por técnica de imunohistoquímica. Citocinas, quimiocinas, corticosterona e 17beta-estradiol foram quantificados por enzima-imunoensaio (ELISA). RESULTADOS: O grupo ME apresentou redução da porcentagem de microvasos perfundidos ( < 30 um) no mesentério comparado ao grupo FO e ao grupo E2, decorridos 180 minutos (p=0,0117), sem alterações no fluxo sanguíneo mesentérico (p=0,3692). Houve aumento na expressão proteica (p < 0,0001) e gênica (p=0,0009) de eNOS no mesentério no grupo E2. Não houve diferenças na expressão proteica e gênica da endotelina-1 entre os grupos. A expressão de ICAM-1 nos microvasos mesentéricos aumentou no grupo ME (p < 0,0001) e a expressão de VCAM-1 foi reduzida no grupo E2 (p=0,0008). Não houve diferenças significativas na expressão de P-selectina entre os grupos (p=0,0675). As análises histopatológicas do pulmão demonstraram aumento do edema (p < 0,0001) e hemorragia (p < 0,0001) no grupo ME comparado aos grupos FO e E2, sem diferenças no número de células inflamatórias (células polimorfonucleares: p=0,4033; células linfomononucleares: p=0,5003). A expressão de iNOS no tecido pulmonar aumentou no grupo ME comparado aos grupos FO e E2 (p < 0,0001). A expressão proteica de eNOS no pulmão diminuiu nos ratos ME e aumentou nos ratos E2 (p=0,0002). A expressão proteica de endotelina-1 no pulmão assim como a expressão gênica pulmonar de eNOS e endotelina-1 não diferiram entre os grupos. Com relação à expressão de moléculas de adesão na microcirculação pulmonar observou-se que os níveis de ICAM-1 não diferiram entre os grupos (p=0,4550); os níveis de VCAM-1 reduziram-se no grupo E2 (p < 0,0001); níveis de PECAM-1 foram reduzidos nos ratos ME (p=0,0037). Observou-se aumento das concentrações séricas de TNF-alfa (p=0,0004) e redução de VEGF sérico (p=0,0380) nos ratos ME. Houve redução das concentrações séricas de CINC-1 (p=0,0020) e aumento de MCP- 1 (p=0,0094) no grupo E2. CONCLUSÃO: O tratamento com o 17beta-estradiol foi efetivo em restaurar a perfusão mesentérica e reduzir a lesão pulmonar associadas à morte encefálica. Sugere-se que o estradiol, como modulador microcirculatório, possa contribuir para a preservação dos órgãos destinados ao transplante / BACKGROUND: Brain death (BD) is associated with hemodynamic instability, microvascular dysfunction and inflammation, which compromise the viability of the organs for transplantation. The hormone 17?-estradiol is known to display vascular protective effects and anti-inflammatory properties. OBJECTIVE: This study aimed to investigate the effects of 17beta-estradiol, as a microcirculatory modulator, in a sudden onset BD model in male rats. METHODS: Male Wistar rats underwent rapid onset BD by inflating a Fogarty catheter in the intracranial space. Rats were randomly divided in three groups: sham-operated rats submitted to trepanation only (SH, n=11); rats submitted to BD (BD, n=11); and rats treated with 17beta-estradiol (E2, 280 ug/kg, iv) 60 min after BD (E2, n=11). Experiments were performed 180 min thereafter. Laser Doppler flowmetry and intravital microscopy were used to evaluate mesenteric microvascular alterations. Gene expression of endothelial nitric oxide synthase (eNOS) and endothelin-1 in the mesentery and lungs were measured by real-time polymerase chain reaction. Protein expression of eNOS, endothelin-1, Pselectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, and platelet/endothelial cell adhesion molecule (PECAM)-1 was investigated by immunohistochemistry. Lung histopathological changes were evaluated by histomorphometry and tissue expression of inducible nitric oxide synthase (iNOS) by immunohistochemistry. Cytokines, chemokines, 17beta- estradiol, and corticosterone were measured by enzyme-linked immunosorbent assay. RESULTS: The proportion of mesenteric perfused small vessels ( < 30 um diameter) was reduced in BD rats compared to SH and E2 rats at 180 min (p=0.0117), without changes in mesenteric blood flow (p=0.3692). Protein expression of eNOS was increased in E2 group (p < 0.0001), as well gene expression of eNOS (p=0.0009). There were no differences in protein and gene expression of endothelin-1 between groups. The expression of ICAM-1 on mesenteric vessels was increased in BD group (p < 0.0001) and expression of VCAM-1 was reduced in E2 rats (p=0.0008). There were no differences in the expression of P-selectin between groups (p=0.0675). Lung histopathological analyses showed increased edema (p < 0.0001) and hemorrhage (p < 0.0001) in BD group compared to SH and E2 groups, without differences in the number of inflammatory cells (polymorphonuclear cells: p=0.4033; lymphomononuclear cells: p=0.5003). The expression of iNOS on lung tissue was increased in BD group, compared with SH and E2 groups (p < 0.0001). Lung protein expression of eNOS decreased in BD rats, and increased in E2 rats (p=0.0002). Protein expression of lung endothelin-1 as well as gene expression of lung eNOS and endothelin-1 did not differ among groups. Regarding the expression of adhesion molecules on lung microcirculation, it was observed that ICAM-1 levels did not differ between groups (p=0.4550); levels of VCAM-1 decreased in E2 group (p < 0.0001); PECAM-1 levels were reduced in BD rats (p=0.0037). BD rats showed increased levels of TNF-alpha (p=0.0004), and a reduction in the levels of VEGF (p=0,0380) in the serum. BD-E2 rats exhibited reduced CINC-1 levels (p=0.0020) and increased levels of MCP-1 (p=0,0094) in the serum. CONCLUSION: Data presented showed that 17beta-estradiol treatment was effective in restoring mesenteric perfusion and reducing lung injury in braindead rats. Estradiol, as a microcirculatory modulator, is a promise therapy to improve organs viability to transplant

INTRODUÇÃO: A hipercolesterolemia provoca alterações inflamatórias no sistema cardiovascular, induzindo disfunção endotelial e mudanças estruturais na microcirculação, com alterações significativas da homeostase vascular, processo este reversível com o tratamento hipolipemiante. Clinicamente, tais fenômenos podem ser demonstrados pela avaliação da reserva de fluxo coronário e da reatividade vascular periférica. A ecocardiografia de perfusão miocárdica em tempo real (EPMTR) possui características que a tornam ideal para a avaliação da microcirculação coronária, como a utilização de contrastes intravasculares, além de ótimas resoluções temporal e espacial. MÉTODOS: 16 pacientes com hipercolesterolemia e sem lesões coronárias obstrutivas (grupo HF) e 10 indivíduos saudáveis, sem doença arterial coronária obstrutiva estabelecida (grupo controle) foram avaliados por EPMTR e por ultrassonografia da artéria braquial em dois momentos: pré-tratamento com atorvastatina no grupo HF (período livre de medicação >6 semanas) e 12 semanas após o primeiro exame. A análise do fluxo miocárdico foi realizada nos 17 segmentos do ventrículo esquerdo obtendo-se índices de volume de sangue relativo no miocárdio (AN), da velocidade do fluxo () e do fluxo miocárdico absoluto (ANx) na condição de repouso e durante a vasodilatação com adenosina. A reserva de fluxo foi definida como a razão entre o fluxo durante vasodilatação e o fluxo do repouso. Para estudo da reatividade vascular periférica, todos os indivíduos foram submetidos à ultrassonografia da artéria braquial, com avaliação dos diâmetros da artéria braquial antes e depois de um período de isquemia de 5 minutos. RESULTADOS: Os dois grupos foram comparáveis quanto à idade, sexo, peso, superfície corpórea, índice de massa corpórea, índice de massa do VE, frequência cardíaca e pressões arteriais sistólica e diastólica, tanto no repouso quanto durante a infusão de adenosina. Os valores evolutivos de LDL-C (mg.dL-1) nos dois momentos foram 106±36 e 107±35; p=NS para o grupo controle vs 278±48 e 172±71; p<0,001 para o grupo HF. Na avaliação inicial, a dilatação braquial estava reduzida nos pacientes do grupo HF 0,08±0,04 vs 0,15±0,02; p<0,001 relativamente ao grupo controle, com aumento do diâmetro arterial basal (mm): 3,42±0,63 vs 3,07±0,53; p<0,001. O grupo HF, quando comparado ao grupo controle na avaliação inicial, apresentava valores mais altos de AN: (dB) 0,56±0,08 vs 0,49±0,05; p=0,02, de (s-1) 0,56±0,14 vs 0,45±0,04; p=0,02 e ANx: (dB.dB-1 s-1) 0,28±0,06 vs 0,20±0,02; p<0,001, maiores valores de AN: durante infusão de adenosina 0,64±0,08 vs 0,57±0,06; p=0,001 e menores reservas de : 2,59±0,61 vs 3,25±0,45; p=0,001 e de ANx: 2,78±0,71 vs 3,43±0,66; p=0,03. Após o uso de atorvastatina, as alterações foram revertidas, tanto na circulação periférica quanto na coronária. CONCLUSÕES: A EPMTR monstrou que em indivíduos com hipercolesterolemia e sem doença coronária obstrutiva existe aumento do fluxo microvascular em repouso e redução da reserva de fluxo miocárdico. Após o tratamento com atorvastatina houve normalização do fluxo em repouso. Adicionalmente, alterações similares ocorreram na circulação periférica dos indivíduos hipercolesterolêmicos, revertidas por utilização da atorvastatina. / BACKGROUND: Hypercholesterolemia induces inflammatory changes on the cardiovascular system, causing endothelial dysfunction and structural alterations of microcirculation, with substantial imbalance of vascular homeostasis. Reduction of blood cholesterol levels can stop these processes. These circulation alterations can be demonstrated by coronary flow reserve and peripheral vascular reactivity evaluation. Real time myocardial perfusion echocardiography (EPMTR) is an excellent method to demonstrate coronary microcirculation alterations, as ultrasound contrast agent has rheological properties close to red cells. Additionally, EPMTR has optimal spatial and temporal resolutions. METHODS: 16 patients with hypercholesterolemia (group-HF) without overt obstructive coronary disease and 10 healthy volunteers (group-C) were evaluated by EPMTR and vascular ultrasound in 2 moments: before atorvastatin treatment (group-HF, >6 weeks free of statin) and 12 weeks after beginning medication (group-HF), or 12 weeks after the first evaluation (group-C). For myocardial blood flow evaluation, the left ventricle was divided into 17 segments, and indexes of myocardial blood volume (AN), blood flow velocity (), and myocardial blood flow (ANx) were obtained for each myocardial segment at rest condition and after adenosine infusion. Myocardial flow reserve was calculated as the hyperemic to rest values of AN, e ANx. Peripheral vascular reactivity was evaluated by vascular ultrasound. Measures of braquial artery diameter were obtained before and after 5 minutes of arterial flow occlusion. RESULTS: Both groups were comparable for age, sex, body weight, body surface area, body mass index, left ventricular mass index, heart rate, and systolic and diastolic arterial blood pressure. These variables were also comparable, under basal or adenosine stress conditions. LDL-C values (mg.dL-1) in different moments (intra-group) were 106±36 and 107±35; p=NS for group-C vs 278±48 and 172±71; p<0,001 for group-HF. Group-HF as compared to group-C had higher initial resting values of AN (dB): 0,56±0,08 vs 0,49±0,05; p=0,02, (s-1): 0,56±0,14 vs 0,45±0,04; p=0,02, and ANx (dBdB-1s-1): 0,28±0,06 vs 0,20±0,02; p<0,001, and higher hyperemic value of AN 0,64±0,08 vs 0,57±0,06; p=0,04, and lesser reserves of 2,59±0,61 vs 3,25±0,45; p=0,01 and of ANx: 2,78±0,71 vs 3,43±0,66; p=0,03. After atorvastatin treatment no difference was observed at rest, hyperemic and reserve values of AN, and ANx between the groups. CONCLUSION: In patients with hypercholesterolemia and without coronary obstruction, there was augmented myocardial blood flow and reduced coronary flow reserve at rest, compared to healthy volunteers. After atorvastatin treatment at rest myocardial blood flow was normalized in those patients. Additionally, similar alterations in peripheral circulation could be demonstrated in hypercholesterolemia, and were reverted with atorvastatin.

No description available.

No description available.

Diabetes mellitus is a chronic disease affecting millions of people worldwide. The degenerative changes caused by diabetes can, however, be controlled through the correct treatment. The outcome of diabetes mellitus depends mainly on the patient's self-management. Health professionals therefore have a major responsibility to assist patients to acquire the essential knowledge, skills and attitudes for self-management. The purpose of this study was to identify diabetic patients and family members' knowledge and views about diabetes mellitus and its treatment regimen. A quantitative descriptive survey design was used. Questionnaires were used to collect data from a convenient sample of diabetic patients and family members. Data was analysed by a computer program called Statistical Package for Social Sciences. Findings revealed that patients and family members lack adequate knowledge on diabetes mellitus and its treatment. Recommendations regarding the required information and assistance to be given to diabetic patients and their family members were formulated. / Health Studies / (MA (Health Studies))

The importance of coronary microcirculatory perfusion is highlighted by the severe impact of microvascular diseases such as diabetes and hypertension on heart function. Recently, highly-detailed three-dimensional (3D) data on ex vivo coronary microvascular structure have become available. However, hemodynamic information in individual myocardial capillaries cannot yet be obtained using current in vivo imaging techniques. In this thesis, a novel data-driven modelling framework is developed to predict tissue-scale flow properties from discrete anatomical data, which can in future be used to aid interpretation of coarse-scale perfusion imaging data in healthy and diseased states. Mathematical models are parametrised by the 3D anatomical data set of Lee (2009) from the rat myocardium, and tested using flow measurements in two-dimensional rat mesentery networks. Firstly, algorithmic and statistical tools are developed to separate branching arterioles and venules from mesh-like capillaries, and then to extract geometrical properties of the 3D capillary network. The multi-scale asymptotic homogenisation approach of Shipley and Chapman (2010) is adapted to derive a continuum model of coronary capillary fluid transport incorporating a non-Newtonian viscosity term. Tissue-scale flow is captured by Darcy's Law whose coefficient, the permeability tensor, transmits the volume-averaged capillary-scale flow variations to the tissue-scale equation. This anisotropic permeability tensor is explicitly calculated by solving the capillary-scale fluid mechanics problem on synthetic, stochastically-generated periodic networks parametrised by the geometrical data statistics, and a thorough sensitivity analysis is conducted. Permeability variations across the myocardium are computed by parametrising synthetic networks with transmurally-dependent data statistics, enabling the hypothesis that subendocardial permeability is much higher in diastole to compensate for severely-reduced systolic blood flow to be tested. The continuum Darcy flow model is parametrised by purely structural information to provide tissue-scale perfusion metrics, with the hypothesis that this model is less sensitive and more reliably parametrised than an alternative, estimated discrete network flow solution.

Les fonctions vasculaires sont régulées par diverses stimulations biochimiques ou mécaniques qui activent les différentes cellules composant les vaisseaux sanguins.Les réponses cellulaires qui en résultent peuvent impliquer une réorganisation du cytosquelette, des changements morphologiques, l'expression de protéines membranaires ou la libération de nombreux médiateurs. Tous ces événements sont susceptibles d'influencer les propriétés mécaniques des cellules. Ainsi, le but de la présente étude est de déterminer l'impact de l'activation de certains récepteurs au niveau des propriétés mécaniques des cellules, des modifications qui pourraient avoir de fortes implications au niveau vasculaire. Pour ce faire, nous avons utilisé deux approches expérimentales permettant d'évaluer des changements morphologiques et mécaniques de très faible amplitude : la microscopie à force atomique (AFM) et la résonance des plasmons de surface (SPR). Nous avons ainsi étudié les effets de l'activation des récepteurs de l'angiotensine II, la thrombine et la bradykinine sur la morphologie et les propriétés mécaniques de modèles cellulaires importants dans l'étude des fonctions vasculaires. Nous avons observé que l'activation du récepteur AT[indice inférieur 1] pour l'angiotensine II induit une réponse mécanique transitoire qui se traduit par une contraction du corps cellulaire, une augmentation du module d'élasticité de la cellule et une diminution de l'intégrité de l'épithélium. Quant à l'activation du récepteur PAR-1 pour la thrombine et du récepteur B[indice inférieur 2] pour la bradykinine, celle-ci provoque aussi une modification de la rigidité des cellules, mais de façon soutenue dans le temps. Ces deux agonistes augmentent aussi l'interaction entre la membrane et le cytosquelette, un phénomène observé par l'augmentation des forces requises pour l'étirement de la membrane cellulaire. Ainsi, la présente étude montre qu'une cellule peut subir des modifications importantes au niveau de ses propriétés mécaniques suivant son activation par différents agonistes, ce qui peut avoir des conséquences directes sur certaines fonctions physiologiques dépendantes des propriétés mécaniques des vaisseaux. En effet, ces changements observés au niveau de la cellule pourraient, entre autres, contribuer au contrôle du diamètre et de la compliance des capillaires, à l'adhésion des cellules inflammatoires ainsi que modifier la perception de stimuli mécaniques par les cellules endothéliales.

There are gaps in the fundamental understanding of the expression of nitric oxide synthases (NOS) in the microvasculature. We examined co-localization of NOS1 (nNOS), NOS2 (iNOS) and NOS3 (eNOS) in the spinotrapezius muscle of young adult male Wistar-Kyoto (WKY) and Spontaneously Hypertensive (SHR) rats according to fiber type using immunohistochemistry and brightfield microscopy. Data regarding fiber distribution, population and morphology data were collected. Alkaline phosphatase staining was used to determine capillary density and average number of capillaries around a fiber. Gel electrophoresis and Western blot techniques were used to compare myosin heavy chain (MHC) protein expression with fiber type population data and to determine NOS1-3 protein expression in whole muscle homogenate. This study should provide a more accurate understanding of differences in NOS expression between these two strains of rats.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

La perfusion est un facteur important dans la viabilité et la fonction du myocarde. Des atteintes microvasculaires diffuses, précédant l'infarctus ou l'insuffisance cardiaque sont impliqués dans bon nombre de pathologies cardiaques. Ce travail vise à améliorer les techniques existantes de mesure quantitatives et non-invasive de la perfusion myocardique par marquage de spins artériels (ASL). La première partie de mon travail de thèse a consisté en la mise place chez la souris d'une technique alternative pour mesurer la perfusion myocardique. Celle-ci est basée sur un marquage pulsé et régulièrement répété afin de construire un état d'équilibre de l'aimantation sous l'influence de la perfusion (approche steady-pulsed ASL). Le modèle théorique associé à cette technique spASL a été développé en parallèle afin de quantifier le flux sanguin tissulaire. Il a été montré que spASL permettait d'obtenir un résultat similaire aux techniques existantes avec en plus, les avantages d'améliorer la sensibilité au signal de perfusion ainsi que de réduire le temps d'acquisition. Dans un second temps, un transfert vers l'imagerie clinique pour une application chez l'homme a été entrepris. Le marquage de type spASL a été conservé et le module de lecture a été adapté aux spécificités de l'imagerie cardiaque chez l'homme pour une acquisition en respiration libre. Un post-traitement dédié qui comprend une correction de mouvement rétrospective a ensuite vu le jour afin d'améliorer la robustesse de nos mesures. Parallèlement aux développements conduits chez l'homme, nous avons exploité l'approche spASL chez l'animal en proposant diverses améliorations en fonction des études menées. / Myocardial blood flow is an important factor of tissue viability and function. Diffuse changes in microcirculation preceding heart failure are involved in various cardiac pathologies. This work aim at improving existing techniques allowing quantitative and non-invasive myocardial perfusion assessment using arterial spin labeling. The first step of my work was to design an alternative approach to quantify myocardial blood flow in mice. The so called steady-pulsed ASL (spASL) is based on a regularly repeated pulsed labeling in order to build up a stationary regime of the magnetization under the influence of perfusion. The associated theoretical model has been developed in parallel to quantify tissue blood flow. We have shown that spASL allows to obtain similar results than the previously employed techniques, with the additional advantages of an increased sensitivity to the perfusion signal and a reduced acquisition time. A transfer towards clinical imaging for human applications was then undertaken. The spASL labeling scheme has been preserved while adapting the readout module to the specificities of cardiac MRI when applied to free-breathing human acquisitions. A dedicated post-processing, which includes a retrospective motion correction, has emerged subsequently to improve the robustness of our measurements. In parallel to the developments made for human studies, some optimization of the spASL technique when applied to rodent have been carried out depending on the conducted studies.