Aujourd’hui, la transplantation est le seul traitement efficace proposé aux patients souffrant d’une insuffisance hépatique fulminante. La nécessité de disposer d’un système de suppléance hépatique transitoire apparaît donc indispensable. C’est dans cet axe que se sont développés les systèmes qualifiés de foies bio artificiels (BAL). Leur principale caractéristique est d’incorporer un bioréacteur hébergeant des cellules pouvant restaurer l’activité hépatiques dans son ensemble. A l’heure actuelle, les hépatocytes primaire humains (HEP) issus de foies de donneurs non transplantables sont considérées comme le meilleur choix. Cependant, leur utilisation reste limitée par leur faible disponibilité et la difficulté à les maintenir différenciés en culture in vitro. Pour remédier à ce dernier point, l’approche la plus prometteuse semble être une co-culture des hépatocytes avec les cellules non parenchymateuses afin de recréer un environnement proche des sinusoïdes hépatiques. Ce travail de thèse repose sur la mise en place d’une nouvelle approche de co-culture tridimensionnelle sous la forme de sphéroïdes, d’HEP primaires avec les principaux types de cellules non-parenchymateuses (les cellules de Kupffer, les cellules endothéliales et les cellules étoilées) selon des proportions spécifiques. Puis de leurs encapsulations dans des billes d’alginate et leurs cultures au sein d’un bioréacteur à lit fluidisé. Ce modèle s’est révélé pertinent et approprié à maintenir les fonctions hépatiques dans le temps. Bien que beaucoup d’optimisation reste à définir, ce travail exploratoire témoigne de l’intérêt de cette approche intéressante pour le progrès des systèmes BAL. / Liver shortage makes transplantation inapplicable to all acute liver failure patients. Bioartificial Iiver (BAL) devices represent a temporary solution for these patients which are thereby bridged tilt Iiver transplantation or regeneration BAL treatment offers blood purification and substitution of metabolic functions through the activity of hepatocytes (HEPs), which are integrated in the device within acclimating containers, so-called bioreactors. Primary human hepatocytes are the ideal cell type to use in BAL, but they are scarcely available and difficult to maintain in vitro. Co-culture of HEPs with supporting cells has been proposed as the most promising strategy for preserving HEP behaviors in in vitro conditions. In fact, assisting cells types hold their ability to influence functional responses of the HEPs by providing them with cues of the native organ.This PhD work proposed a novel approach of co-culture for the functional sustain and preservation of the HEPs in the environment of the fluidized bed bioreactor (designed in our Iaboratory). Definition of this model took inspiration from the cellular organization in the organ; therefore, it employed three major sinusoidal non-parenchymal cell populations (liver sinusoidal, Kupffer, and hepatic stellate cells) which, together with HEPs, were cultured with three-dimensional arrangement (spheroids) and according to specific proportions. The resulting model was characterized in terms of functional benefits for the HEPs, and then applied in the microenvironment of alginate beads, which provide cells with immunological and mechanical protection in the fluidized bed bioreactor. This spheroidal multi-cultured model revealed its potentiality in sustaining in vitro HEP behaviors over time. Although much remains to be refined, this model may represent an interesting approach for the progress of BAL

The thesis deals with the classification of the retinal blood vessels in retinal image data. The first part of the thesis deals with the anatomy of the human eye and focuses on the description of the retina and its blood circulation. It further describes the principle of fundus camera and experimental video ophthalmoscope. The second part of the thesis is devoted to a literature search of academic publications that deal with the classification of the retinal vessels into arteries and veins. Subsequently, the principle of selected machine learning methods is presented. Based on the literature research, two methods for the classification of the blood vessels were proposed, the first one using the SVM classifier and the second one using the convolutional neural network U-Net. At the end, the analysis of vascular pulsations was performed. The practical part of the thesis was carried out in Matlab programming interface and images from the RITE, IOSTAR and AFIO database were used for classification and the retinal video sequences taken with an experimental video ophthalmoscope were processed in the analysis of pulsations.

This master thesis deals with detection of blood-vessel bifurcations in retinal images and its properties. There are explained procedure of taking photographs of retina by fundus camera, optical coherence tomography (OCT) and scanning laser opthalmoscope (SLO) and properties of fundus images are described. In this thesis are mentioned some effective thresholding methods and there are explained the most important morphological operations with binary images, as well as with grayscale images. Detected bifurcations are used for image registration with second-order polynomial transformation using corresponding bifurcations.

From biometrical point of view, main features of retina are fovea, optic nerve and blood vessel tree. Blood vessel tree is unique for each person and this biological feature is used in biometric systems for person-recognition by retinal images. This document describes methods for optic disc and fovea localization, method for vessel tree segmentation, which is based on well-known \emph{Matched filters} method and also describes method for localization of blood vessel bifurcations. Main goal of this thesis is creation of program which can automatically preprocess input image, segment blood vessels and localize vessel bifircations. The program is implemented in Java with OpenCV library.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Factors released from coronary perivascular adipose tissue (PVAT), which surrounds large coronary arteries, have been implicated in the development of coronary disease. However, the precise contribution of coronary PVAT-derived factors to the initiation and progression of coronary vascular dysfunction remains ill defined. Accordingly, this investigation was designed to delineate the mechanisms by which PVAT-derived factors influence obesity-induced coronary smooth muscle dysfunction. Isometric tension studies of coronary arteries from lean and obese swine demonstrated that both lean and obese coronary PVAT attenuate vasodilation via inhibitory effects on smooth muscle K+ channels. Specifically, lean coronary PVAT attenuated KCa and KV7 channel-mediated dilation, whereas obese coronary PVAT impaired KATP channel-mediated dilation. Importantly, these effects were independent of alterations in underlying smooth muscle function in obese arteries. The PVAT-derived factor calpastatin impaired adenosine dilation in lean but not obese arteries, suggesting that alterations in specific factors may contribute to the development of smooth muscle dysfunction. Further studies tested the hypothesis that leptin, which is expressed in coronary PVAT and is upregulated in obesity, acts as an upstream mediator of coronary smooth muscle dysfunction. Long-term administration (3 day culture) of obese concentrations of leptin markedly altered the coronary artery proteome, favoring pathways associated with calcium signaling and cellular proliferation. Isometric tension studies demonstrated that short-term (30 min) exposure to leptin potentiated depolarization-induced contraction of coronary arteries and that this effect was augmented following longer-term leptin administration (3 days). Inhibition of Rho kinase reduced leptin-mediated increases in coronary artery contractions. Acute treatment was associated with increased Rho kinase activity, whereas longer-term exposure was associated with increases in Rho kinase protein abundance. Alterations in Rho kinase signaling were also associated with leptin-mediated increases in coronary vascular smooth muscle proliferation. These findings provide novel mechanistic evidence linking coronary PVAT with vascular dysfunction and further support a role for coronary PVAT in the pathogenesis of coronary disease.

No description available.

Von Hippel-Lindau (VHL) syndrome is an autosomal dominant predisposition to cancer in neurological tissues, the kidneys, adrenal glands, pancreas, and liver, including neurological hemangioblastoma (HB), pheochromocytoma (PCC), pancreatic neuroendocrine tumors (PNET), pancreatic and renal cysts, and clear cell renal cell carcinoma (ccRCC). The disease process follows Knudson's two-hit model, requiring spontaneous loss or mutation of a normal VHL tumor suppressor allele to induce expression of the disease. VHL syndrome principally involves dysregulation of oxygen sensing pathways including the Hypoxia Inducible Factor (HIF)-Vascular Endothelial Growth Factor-A (VEGF-A) and HIF-Erythropoietin (EPO) pathways. RNA sequencing (RNA-Seq) data from our previously published experiments revealed a potentially novel VEGF-A splice variant with excision of the VEGF Receptor-1 (VEGFR-1)/Flt-1 binding domain, rendering this isoform resistant to native down-regulation. Additionally, phenotypic changes were observed in adult VHL mutant mice, specifically very red appearing extremities with prominently visible vasculature. In order to determine the etiology of this phenotype, we observed red blood cell count, Epo gene expression levels, and arterialization of the blood vessels in these experimental mice as compared to littermate controls. Current research into the VEGF-A isoform is ongoing in the lab, and preliminary evidence for the etiology of the apparent chronic erythema phenotype is inconclusive due to lack of experimental replicates due to COVID-19 quarantine orders. / Master of Science / Von Hippel-Lindau (VHL) syndrome is characterized by cancer development primarily in the brain and spinal cord, kidneys, adrenal glands, pancreas, and liver. VHL syndrome involves mutations which render the VHL gene dysfunctional. Since the VHL gene's normal role is one of preventing cancer development, sensing oxygen levels, and impacting blood vessel development, it follows that the loss of this gene results in tumor development with a rich blood vessel network. One of the downstream effectors of this process is a signaling molecule called Vascular Endothelial Growth Factor-A (VEGF-A). Our lab found a unique variant of VEGF-A, which may be overactive in the body in the setting of VHL disease. Additionally, we noted that our VHL mutant mice turned very red, and we sought to identify the biological cause of this phenomenon. In order to determine the cause of this redness, we studied red blood cell counts and their regulatory gene (Erythropoietin, EPO), as well as potential blood vessel abnormalities using high-power microscopy.

The cardiovascular system of bilaterians developed from a common ancestor. However, no endothelial cells exist in invertebrates demonstrating that primitive cardiovascular tubes do not require this vertebrate-specific cell type in order to form. This raises the question of how cardiovascular tubes form in invertebrates? Here we discovered that in the invertebrate cephalochordate amphioxus, the basement membranes of endoderm and mesoderm line the lumen of the major vessels, namely aorta and heart. During amphioxus development a laminin-containing extracellular matrix (ECM) was found to fill the space between the basal cell surfaces of endoderm and mesoderm along their anterior-posterior (A-P) axes. Blood cells appear in this ECM-filled tubular space, coincident with the development of a vascular lumen. To get insight into the underlying cellular mechanism, we induced vessels in vitro with a cell polarity similar to the vessels of amphioxus. We show that basal cell surfaces can form a vascular lumen filled with ECM, and that phagocytotic blood cells can clear this luminal ECM to generate a patent vascular lumen. Therefore, our experiments suggest a mechanism of blood vessel formation via basal cell surfaces in amphioxus and possibly in other invertebrates that do not have any endothelial cells. In addition, a comparison between amphioxus and mouse shows that endothelial cells physically separate the basement membranes from the vascular lumen, suggesting that endothelial cells create cardiovascular tubes with a cell polarity of epithelial tubes in vertebrates and mammals.

Estudou-se por morfologia, morfometria e imuno-histoquímica o remodelamento vascular (moléculas de adesão), epitelial (moléculas de adesão) e intersticial (colágeno V e células imunes) nos três tipos maiores de pneumonias intersticiais idiopáticas: em 62 casos de IPF, 22 casos de NSIP e 25 casos de AIP. O impacto dessas alterações foi avaliado nas provas de função, sobrevida e prognóstico. Demonstrou-se que o remodelamento vascular ativo e fibroelastótico é diretamente proporcional ao grau de atividade parenquimatosa principalmente na UIP. O colágeno V, o mapeamento das células imunes, o aumento da atividade endotelial e epitelial tiveram impacto no espectro diferencial e possivelmente na patogênese das três pneumonias intersticiais estudadas. A resposta imune celular na UIP teve impacto na sobrevida dos pacientes / Studied for morphology, morphometry and immunohischemistry the vascular (adhesion molecules), epithelial (adhesion molecules) and interstitial (collagen V and immune cells) remodeling in the three major types of idiopathic interstitial pneumonias: in 62 cases of IPF, 22 cases of NSIP, and 25 cases of AIP. The impact of these alterations was evaluated in the function tests, survival and prognostic. We demonstrated that the active and fibroelastotic vascular remodeling is directly proportional to the degree of parenchymal activity, mainly in the UIP. Collagen V, mapping of the immune cells, increase of the endothelial and epithelial activity had possibly impact in the distinguishing specter and in pathogenesis of the three interstitial pneumonias studied. The cellular immune reply in the UIP it had impact in survival of the patients