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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

The Role of miR-126/126* in Microenvironmental Regulation of Cancer Metastasis

Zhang, Yun January 2013 (has links)
<p>Cancer metastasis is the cause of about 90% of cancer patients' deaths. Despite significant improvements in the past three decades in understanding the molecular bases of oncogenic transformation of cancer cells, little is known about the molecular mechanisms underlying tumour cells' alteration of their microenvironment, entrance into the circulation, and colonization of distant organs. In recent years, accumulating evidence has indicated that tumour microenvironment, which consists of a variety of cell types and extracellular matrix components&#65292;plays an important role in regulating the metastatic abilities of carcinoma cells. Co-opted by cancer cells, those stromal cells promote tumour progression via multiple mechanisms, including enhancement of tumour invasiveness, elevation of angiogenesis, and suppression of immune surveillance activity. </p><p>Using a series of human breast cancer cell lines with different metastatic potentials <italic>in vivo</italic>, we performed an unbiased screen examining expression of miRNAs, and found that miR-126 and miR-126*, whose expression are regulated by methylation of the promoter of their host gene Egfl7 inside tumour cells, were significantly negatively correlated with metastatic potential. Using both mouse xenograft models and <italic>in vitro</italic> assays, we showed that this pair of miRNAs suppressed breast cancer metastasis through shaping the tumour microenvironment without changing tumour cell autonomous properties. Specifically, miR-126 and miR-126* act independently to suppress the sequential recruitment of mesenchymal stem cells (MSCs) and inflammatory monocytes into the primary tumour stroma, consequently inhibiting lung metastasis by breast tumour cells. Mechanistically, these miRNAs directly inhibit the production of stromal cell-derived factor-1 alpha (Sdf-1&alpha;, also known as Cxcl12), and indirectly suppress the expression of chemokine (C-C motif) ligand 2 (Ccl2) by the cancer cells within the tumour mass in an Sdf-1&alpha;-dependent manner. In addition, in contrast with the majority of reports which have shown incorporation of only the guiding strand of the miRNA duplex into the mRNA-targeting RNA induced silencing complex (RISC), both strands of the miR-126 RNA duplex are maintained at a similar level and suppress Sdf-1&alpha; expression independently. </p><p>Collectively, we have determined a dynamic process by which the composition of the primary tumour microenvironment could be altered via a change in the expression of two tumour-suppressive miRNAs derived from a single miRNA precursor to favor metastasis by breast cancer cells. Importantly, this work provides a prominent mechanism to explain the clinical correlation between reduced expression of miR-126/126* and poor metastasis-free survival of breast cancer patients.</p> / Dissertation
32

Role of the SDF-1/CXCR4/eNOS Signaling Pathway in Chronic Kidney Disease

Chen, Li-Hao (Henry) 21 November 2012 (has links)
Loss of the renal microvasculature is a common feature of almost all forms of chronic kidney disease (CKD). Here we explored the role of the angiogenic chemokine stromal cell-derived factor-1-alpha (SDF-1) and its cognate receptor CXCR4 in experimental and human CKD. CXCR4 was present on endothelial cells and podocytes, while SDF-1 was detectable on podocytes, arteriolar smooth muscle cells, interstitial fibroblasts and occasional endothelial cells. CXCR4 mRNA was elevated in the kidneys of rats with CKD and chronic antagonism of CXCR4 accelerated renal decline and capillary loss. Acute SDF-1 infusion activated glomerular endothelial nitric oxide synthase (eNOS) in vivo, while functional response to SDF-1 was impaired in glomerular endothelial cells derived from eNOS-/- mice. Finally, CXCR4 mRNA was also found to be increased in biopsies of patients with secondary focal segmental glomerulosclerosis. These observations indicate that local eNOS-dependent SDF-1/CXCR4 signaling exerts a compensatory reno-protective effect in the setting of CKD.
33

Role of the SDF-1/CXCR4/eNOS Signaling Pathway in Chronic Kidney Disease

Chen, Li-Hao (Henry) 21 November 2012 (has links)
Loss of the renal microvasculature is a common feature of almost all forms of chronic kidney disease (CKD). Here we explored the role of the angiogenic chemokine stromal cell-derived factor-1-alpha (SDF-1) and its cognate receptor CXCR4 in experimental and human CKD. CXCR4 was present on endothelial cells and podocytes, while SDF-1 was detectable on podocytes, arteriolar smooth muscle cells, interstitial fibroblasts and occasional endothelial cells. CXCR4 mRNA was elevated in the kidneys of rats with CKD and chronic antagonism of CXCR4 accelerated renal decline and capillary loss. Acute SDF-1 infusion activated glomerular endothelial nitric oxide synthase (eNOS) in vivo, while functional response to SDF-1 was impaired in glomerular endothelial cells derived from eNOS-/- mice. Finally, CXCR4 mRNA was also found to be increased in biopsies of patients with secondary focal segmental glomerulosclerosis. These observations indicate that local eNOS-dependent SDF-1/CXCR4 signaling exerts a compensatory reno-protective effect in the setting of CKD.
34

Design and Implementation of an Asynchronous Pipelined FFT Processor / Design och implementering av en asynkron pipelinad FFT processor

Claesson, Jonas January 2003 (has links)
FFT processors are today one of the most important blocks in communication equipment. They are used in everything from broadband to 3G and digital TV to Radio LANs. This master's thesis project will deal with pipelined hardware solutions for FFT processors with long FFT transforms, 1K to 8K points. These processors could be used for instance in OFDM communication systems. The final implementation of the FFT processor uses a GALS (Globally Asynchronous Locally Synchronous) architecture, that implements the SDF (Single Delay Feedback) radix-22 algorithm. The goal of this report is to outline the knowledge gained during the master's thesis project, to describe a design methodology and to document the different building blocks needed in these kinds of systems.
35

Bone Marrow Targeted Liposomal Drug Delivery Systems

Baki, Mert 01 June 2011 (has links) (PDF)
Homing is the process that stem cells move to their own stem cell niches under the influence of chemokines like stromal-derived factor-1&alpha / (SDF-1&alpha / ) upon bone marrow transplantation (BMT). There is a need for increasing homing efficiency after BMT since only 10-15% of the transplanted cells can home to their own niches and a limited amount of donor marrow can be transplanted. In this study, we aimed to develop and characterize bone marrow targeted liposomal SDF-1&alpha / delivery system prepared by extrusion method. Alendronate conjugation was chosen to target the liposomes to bone marrow microenvironment, particularly the endosteal niche. Optimization studies were conducted with the model protein (
36

La construction psychique de l'errance : Stratégies institutionnelles d'offres et de demandes

Boinot, Karine 03 February 2007 (has links) (PDF)
Cherchant à comprendre les dynamiques amenant des personnes sans abri en situation d'errance, nous analysons les dispositifs existants en questionnant leur accès afin de parvenir à des objectifs opérationnels concernant les politiques préventives et curatives et les pratiques professionnelles. Dans une conception plurifactorielle de l'errance, nous étudions sa fonction sur le plan de l'économie psychique. Dans une réflexion sur la territorialité et sur l'errance, nous montrons comment l'exclusion, donne au corps une place centrale condensant espace psychique, physique et social du sujet. Nous interrogeons ce que l'exclusion renvoie aux institutions en tant qu'entreprises managériales des sujets SDF en termes d'incasabilité. D'une déchéance « privée » à une « déchéance « publique », le mouvement de soi à l'objet interrogeant la position subjective, il s'agit de caractériser la stratégie défensive du sujet SDF. Au travers de la dimension pulsionnelle autour du regard, analyser les effets contre-transférentiels produits. Contraints à une visibilité permanente, avec une notion d' « obscénité » relevant d'une dimension philosophique de l'insolence, nous évoquons l'adoption d'une position cynique ; figure générique se symptomalisant en figures paradigmatiques : le monstre, le bouffon et le dissident. Visant une restitution de la dimension subjective, à travers l'étude de la subjectivation et de la réification dont les sujets SDF sont l'objet, nous interrogeons la relation subjective, les formes prises du fait de la position activiste du sujet SDF, les représentations sociales des intervenants ainsi que les relations et les conduites établies. L'objet est de mettre à l'épreuve de la clinique le projet énoncé par Olivier Douville de prendre la mesure des facteurs excluants sur la structuration du psychisme.
37

SDF-1/IGF-1 conjugated to a PEGylated fibrin matrix as a treatment for an ischemia reperfusion injury in skeletal muscle repair

Pham, Chantal Bich Phuong 26 April 2013 (has links)
Ischemia/reperfusion (I/R) injury causes extensive damage to skeletal muscle, often resulting in prolonged functional deficits. This current study determines the efficacy of controlled release of SDF-1α and IGF-1 by conjugation to biodegradable, polyethylene glycol, (PEG)ylated fibrin gel matrix in skeletal muscle repair of an I/R injury. Male Sprague-Dawley rats underwent a 2-hour tourniquet induced I/R injury on their hind limbs. Twenty-four hours post injury the following treatments were administered: PEGylated fibrin gel (PEG-Fib), SDF-1 conjugated PEGylated fibrin gel (PEG-Fib/SDF-1), or dual protein IGF-1 and SDF-1 conjugated PEGylated fibrin gel (PEG-Fibrin/SDF-1/IGF-1. Following 14 days after injury, functional and histological evaluations were performed. There was no significant difference in maximum tetanic force production recovery between PEG-Fib and PEG-Fib/SDF-1 groups. However, PEG-Fib/SDF-1/IGF-1 group resulted in significant improvement of force production relative to the other treatment groups. The same results were found for specific tension. Histological analysis revealed a greater distribution of small myofibers in the PEG-Fib/SDF-1 group than the PEG-Fib group, while the PEG-Fib/SDF-1/IGF-1 group had the smallest distribution of small fibers and similar to controls (uninjured). There were also a greater number of centrally located nuclei in the PEG-Fib/SDF-1 group than the PEG-Fib group, while the PEG-Fib/SDF-1/IGF-1 group had similar values to controls. Although these results confirm the protective role of exogenous IGF-1, SDF-1 did not have an effect on skeletal muscle repair. / text
38

Molecular Mechanisms of E. coli Shiga Toxin Pathogenesis

Petruzziello, Tania Nadia 31 August 2012 (has links)
Shiga toxin-producing E. coli (STEC) comprise a group of pathogenic organisms that elaborate a family of protein exotoxins known as Shiga toxins (Stxs). Intestinal infection with these organisms may lead to hemorrhagic colitis and hemolytic uremic syndrome, a life-threatening condition characterized by thrombocytopenia, non-immune hemolytic anemia, and acute renal failure. Vascular endothelial damage is believed to be a key initiating event in Stx-mediated diseases. At the molecular level, these toxins depurinate human 28S rRNA and inhibit translation. In addition, at concentrations that only minimally affect global protein synthesis, they have been found to alter expression of specific target genes. To better understand the endothelial damage induced by Stx, we investigated the global effects of Stx on endothelial gene expression, and defined a specific group of genes whose expression was altered by the toxin. Of interest, the CXCR4/CXCR7/SDF-1 chemokine pathway, a pathway central to vascular biology, was activated by Stx. In vitro studies demonstrated that Stx enhanced both transcript levels of these molecules, as well as their association with ribosomes. To define the relevance of these findings in vivo, a mouse model was established and key changes were noted in plasma and tissue content of CXCR4/CXCR7/SDF-1 following Stx exposure. Inhibition of CXCR4/SDF-1 interaction decreased indices of endothelial activation and organ injury and improved animal survival. Importantly, in children infected with E. coli O157:H7, plasma SDF-1 levels were significantly elevated in individuals who progressed to hemolytic uremic syndrome. A second pathway critical to endothelial health and function is VEGF signaling. Of interest, our endothelial gene expression analyses revealed changes in this pathway in vitro. VEGF mRNA association with cellular polyribosomes increased following Stx treatment. Further studies in vivo demonstrated decreased cardiac function and blood pressure, and increased vascular permeability in specific tissues. VEGF, an important inducer of vascular permeability, increased in mouse plasma. Additionally, altered mRNA expression was observed in key organs, such as the kidney and heart, following Stx challenge. Inhibition of VEGF significantly improved survival of animals treated with Stx, indicating that VEGF plays a role in Stx-mediated pathogenesis. Moreover, in vitro studies demonstrated that Stx-mediated endothelial permeability was attenuated in the presence of a VEGF inhibitor. Taken together, these data indicate that E. coli-derived Stxs induce pathological changes in two pathways key to vascular biology. These pathways represent novel targets for the development of preventative and therapeutic strategies for complications associated with Shiga toxin-producing E. coli infection.
39

Molecular Mechanisms of E. coli Shiga Toxin Pathogenesis

Petruzziello, Tania Nadia 31 August 2012 (has links)
Shiga toxin-producing E. coli (STEC) comprise a group of pathogenic organisms that elaborate a family of protein exotoxins known as Shiga toxins (Stxs). Intestinal infection with these organisms may lead to hemorrhagic colitis and hemolytic uremic syndrome, a life-threatening condition characterized by thrombocytopenia, non-immune hemolytic anemia, and acute renal failure. Vascular endothelial damage is believed to be a key initiating event in Stx-mediated diseases. At the molecular level, these toxins depurinate human 28S rRNA and inhibit translation. In addition, at concentrations that only minimally affect global protein synthesis, they have been found to alter expression of specific target genes. To better understand the endothelial damage induced by Stx, we investigated the global effects of Stx on endothelial gene expression, and defined a specific group of genes whose expression was altered by the toxin. Of interest, the CXCR4/CXCR7/SDF-1 chemokine pathway, a pathway central to vascular biology, was activated by Stx. In vitro studies demonstrated that Stx enhanced both transcript levels of these molecules, as well as their association with ribosomes. To define the relevance of these findings in vivo, a mouse model was established and key changes were noted in plasma and tissue content of CXCR4/CXCR7/SDF-1 following Stx exposure. Inhibition of CXCR4/SDF-1 interaction decreased indices of endothelial activation and organ injury and improved animal survival. Importantly, in children infected with E. coli O157:H7, plasma SDF-1 levels were significantly elevated in individuals who progressed to hemolytic uremic syndrome. A second pathway critical to endothelial health and function is VEGF signaling. Of interest, our endothelial gene expression analyses revealed changes in this pathway in vitro. VEGF mRNA association with cellular polyribosomes increased following Stx treatment. Further studies in vivo demonstrated decreased cardiac function and blood pressure, and increased vascular permeability in specific tissues. VEGF, an important inducer of vascular permeability, increased in mouse plasma. Additionally, altered mRNA expression was observed in key organs, such as the kidney and heart, following Stx challenge. Inhibition of VEGF significantly improved survival of animals treated with Stx, indicating that VEGF plays a role in Stx-mediated pathogenesis. Moreover, in vitro studies demonstrated that Stx-mediated endothelial permeability was attenuated in the presence of a VEGF inhibitor. Taken together, these data indicate that E. coli-derived Stxs induce pathological changes in two pathways key to vascular biology. These pathways represent novel targets for the development of preventative and therapeutic strategies for complications associated with Shiga toxin-producing E. coli infection.
40

En röd tråd – eller High Chaparall? : -En studie om implementeringsarbetet av spelarutbildningsplanen i gräsroten

Dorch, Pontus, Servin, Melker, Wahlgren, Jesper January 2018 (has links)
Syftet med denna studie är att undersöka hur tränarna i gräsrotsföreningarna arbetar i relation till Svenska Fotbollförbundets spelarutbildningsplan, samt att kartlägga hur specialdistriktsförbunden arbetar med att implementera spelarutbildningsplanen i deras dagliga verksamhet. Vidare undersöks vilket stöd tränarna i gräsrotsföreningarna vill ha från sitt specialdistriktsförbund. Studien tar sin utgångspunkt i ramfaktorteorin som syftar till att förklara sambandet mellan resultatet och undervisningens ramar som utbildningen ger. För att besvara studiens syfte har en kvalitativ datainsamling gjorts där semistrukturerade respondentintervjuer tillämpats. Respondenterna representerar tre stycken specialdistriktsförbund och nio stycken tränare i gräsrotsföreningar.   Resultatet och analysen ger en bild av hur relationen ser ut mellan specialdistriktsförbunden och tränarna i gräsrotsföreningarna. Det visade sig att de olika specialdistriktsförbunden arbetar utefter olika strategier för att nå ut med spelarutbildningsplanen till gräsrotstränarna. Vidare kunde det identifieras vikten av en tydlig strategi och en gemensam röd tråd mellan organisationerna för ett lyckat implementeringsarbete. Det upptäcktes att en viktig länk mellan specialdistriktsförbunden och tränarna är organisationsledarna i gräsrotsföreningarna. Det medför att informationen stannar på föreningsnivå och inte når ut till tränarna. Därmed kunde det urskiljas ett samband där tränarna inte hade full insyn i spelarutbildningsplanen och att verksamheten därmed styrs utifrån deras egna föreställningar och kompetens snarare än efter en röd tråd.

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