VictorJuiz/thesis huggingface dataset:
Bidirectional co-signalling between the erythropoietin receptor and stem cell derived tyrosine kinase

Friend virus-mediated erythroleukemia is a well-established model of murine oncogenesis. Key molecular events include constitutive activation of the EPO-R as well as expression and kinase activity of Sf-STK. While both receptors are essential in Friend disease, it is unknown whether Sf-STK modulates EPO-R-mediated signalling. In this study we show constitutive co-immunoprecipitation of EPO-R with both Sf-STK and STK. Furthermore, we demonstrate that EPO-R and STK participate in bi-directional cross-talk and co-stimulation, resulting in enhanced tyrosine phosphorylation of both receptors. Unlike EPO-R, STK ligand-independent tyrosine phosphorylation was dependent on its kinase activity. STK was shown to co-regulate specific EPO-dependent signalling pathways. Co-operative phosphorylation was observed for ERK 1/2 and PKB, but not JAK2, STAT1, STAT5, SAPK and p38, in a GAB2-dependent manner. Additionally, STK expression enhanced EPO-regulated expression of cis and socs-3. This work suggests that Sf-STK contributes to Friend disease by enhancing proliferative and survival signals downstream of the EPO-R.
The quality of civil society participation in national education sector policy processes: a case study of Mali

This thesis explores the participation of Mali's civil society actors in policy design and implementation processes relating to Mali's education sector program, PRODEC (Programme Décennal de Développement de l'Education). Drawing from scholarly literature, this research applies concepts of civil society, governance of education and participation to civil society actors in their support, negotiation, interpretation, and contestation of national education sector policy. The timeframe is from the early 1990s to the mid-2000s. The study examines the dramatic changes of that period, including the expansion of community schools and the introduction of education decentralization. Particular attention is paid to: the variation in experiences between different types of civil society actors; the relationships of civil society actors with government and with international donors; and the relationships between civil society actors themselves. The study identifies six major factors which influence the quality of civil society actors' participation in policy design and implementation processes.
Mgat5, a regulator of metabolic homeostasis in mice

Golgi beta1,6N-acetylglucosaminyltransferase V (Mgat5) produces beta1,6GIcNAc-branched N-glycans on glycoproteins, which increases their affinity for galectins and opposes loss from cell surface to constitutive endocytosis. Oncogenic transformation increases Mgat5 expression, and enhances sensitivities to growth factors, cell motility and tumour metastasis. Therefore, I explored growth and tissue renewal of Mgat5-/- mice, and found that they are hypoglycaemic, resistant to weight-gain, hypersensitive to fasting, display increased oxidative respiration, reduced fecundity and decreased serum leptin. These phenotypes are similar to that of calorie restricted (CR) rodents; however, unlike CR animals, Mgat5-/- mice have accelerated loss of muscle and bone mass and reduced lifespan. CR-induced longevity involve downregulation of the PI3K/Akt/TOR pathway, downstream of many growth factor receptors including EGF, PDGF and IR. In this regard, Mgat5-/- primary MEFs and macrophages are suppressed in MAPK activation in response to EGF, PDGF, IGF, and FCS. However, muscle satellite cells and bone marrow osteoblasts revealed a FCS-induced signalling imbalance, favouring Smad2/3 activation over Erk, which may contribute to reduced growth, self-renewal and longevity of the Mgat5-/- animals. Pten opposes PI3K/Akt signalling and is a potent tumour suppressor. Mgat5 +/- Pten+/- and Mgat5-/- Pten +/- mutant mice showed a small increase in lifespan compared with Pten+/- mice, due to an apparent delay in tumour progression. Primary Pten+/-Mgat5-/- MEFs are normalised for Akt activation and cell spreading, and Pten+/- MEFs have enhanced L-PHA staining, suggesting that Mgat5 structures are regulated by P13K signalling. Aged CR rodents exhibit decreased oxidative damage, implicating either decreased ROS production or elevated antioxidant activity. I demonstrated that Mgat5-/- primary MEFs have decreased glucose uptake and mitochondrial ROS. Unlike WT control, PyMT Mgat5-/- cells fail to down regulate glucose transport, protein synthesis, ROS and activation of Erk and Akt following serum withdrawal. PyMT transformation reveals that Mgat5-deficiency not only impairs positive growth signalling, but also suppresses negative growth regulation, allowing for proliferation and tumourigenicity. Mgat5 participates upstream of PyMT signalling through N-glycan modification of growth factor receptors, but also downstream of Akt signalling through its dependence on glucose uptake for supply of UDP-GlcNAc. Therefore, Mgat5 enhances cellular signalling and growth, and metabolism and longevity in the animal.
Characterization of the RNA translocation of Potato Virus X (PVX) into chloroplast

Previous studies demonstrated that the capsid protein (CP) and RNA of Potato Virus X (PVX) accumulate within chloroplasts of transgenic potato plants carrying the tandem 8kD and CP genes of the virus. To elucidate the mechanism(s) of this RNA translocation, transgenic tobacco plants carrying variations of the 8kD-CP construct were produced. Subsequent RT-PCR analyses of total chloroplastic RNA, not only authenticated the RNA translocation event, but also suggested an interesting mechanism for it. Contrary to the proposed hypothesis, transcripts of the constructs with either the 8kD protein or the CP knocked out were shown to successfully enter chloroplasts. The data suggested that neither the 8kD protein nor the CP, otherwise known to mediate cell-to-cell transport of PVX RNA, were responsible for the observed RNA translocation into chloroplasts. Furthermore, it was postulated that a particular sequence within the region (possibly the IRBS of CP), along with host factor(s), may act as an "RNA tractor" into chloroplasts.
Factors affecting hepatic drug removal: Red cell carriage and microcirculation in harmol metabolism by perfused rat liver

Binding and hepatic artery (HA) bypass effects were investigated with harmol which exhibited high extraction ratio (E), red blood cell (RBC) distribution and sulfation (S) upstream of glucuronidation (G) in rat liver. The RBC-to-plasma efflux rate constant (krp) was too rapid to be characterized in vitro . The almost complete extraction of harmol during the distribution phases of portal vein (PV)-perfused livers (<3 min) resulted in disequilibrium between RBC and plasma, allowing estimation of krp (0.074 min−1 ) which corresponded to a long RBC turnover time (13 min). Upon dual perfusion with PV and HA at flow ratios of 12:0 and 8:4 ml/min for harmol (3.2 to 120 μM) delivery to the single-pass rat liver preparation, the presence of HA reduced S at low concentrations but did not affect E, G nor S/G. The study revealed a red cell carriage for harmol and evidence of HA bypass of the rat liver.
Formation of hybrid particles by phase separation-induced heterocoagulation of a polyferrocenylsilane polyelectrolyte with silica

Hybrid organometallic-inorganic particles with a core-shell structure have been synthesized with silica nanoparticles and [fcSiMe(CH2CH 2Ch2NH3Cl)]n, 1, a polyferrocenylsilane-based polycation in a two step process. In the first step, monodisperse, negatively charge silica nanoparticles (dave = 493.2 nm by PCS; dave = 390.4 nm by SEM) were coated with 1 in water via an electrostatic self-assembly route. The zeta potential measurements before (ζ = −52.4mV) and after (ζ = +70.9mV) the treatment with the polyelectrolyte shows that the assembly was successful. In order to increase the thickness of the polymer coating, acetone, a non-solvent for 1, was introduced slowly to the system to induce controlled phase separation of 1. The resulting phase-separated polymer nanoclusters of 1 undergoes heterocoagulation with the polymer-coated particles from the first step to produce a core-shell structure with d ave = 696.2 nm by photon correlation spectroscopy and d = 482.8 nm by image analysis of scanning electron micrographs. The Hildebrand solubility parameter (δ) for poly(ferrocenylmethylphenylsilane) was determined to be 19.4 MPa−1 through an indirect gel swelling method. The quasi-ternary phase diagram of poly(ferrocenylmethylphenylsilane) in xylenes and n-decane was constructed for room temperature to 70°C.
Long-horizon regression test of mean reversion: a finite-sample analysis

In the past two decades, long-horizon regression has become a popular choice for testing mean reversion in stock prices. Due to an overlapping and multi-period return summation, a finite-sample analysis of sample long-horizon regression coefficients is complicated and largely unavailable in the literature. Empirical studies rely almost entirely on asymptotic tests that can have serious size distortions and be highly unreliable in finite samples. We fill the void by providing a finite-sample analysis of the long-horizon regression under the assumption that stock returns follow a multivariate elliptical distribution. First, we derive analytical expressions for the moments of the OLS estimator of long-horizon regression slope coefficient, and provide simple formulas that approximate the mean and variance extremely well. Second, we develop efficient numerical procedures to compute the exact distribution, allowing us to perform an exact test. In addition, we propose a simple and reliable approximate test assuming the coefficient estimate to follow a normal distribution. Third, we analyze the size and power of the exact test under various popular alternatives. Using the exact test, we find that the power of the long-horizon regression test is very sensitive to the choice of the return horizon. Finally, when applied to the empirical data, the exact test lends less support of mean reversion than asymptotic tests. Even such moderate evidence is mainly due to the pre-1941 data.
Identification of new components of the MHC class I peptide loading complex

In this thesis, I sought to identify novel components of the "peptide loading complex" (PLC) that is involved in delivering peptide ligands to major histocompatibility complex (MHC) class I molecules. An anti-tapasin affinity column was used for the large-scale isolation of the PLC from EL4 cell microsomes. The isolated PLC was separated on an SDS-PAGE gel and protein components were visualized with silver staining. Proteins of interest were processed for tandem mass spectrometry analysis. GenBank database searching with information obtained from the mass spectrometry analysis revealed three novel components, heat shock cognate protein 70 (Hsc70), ribophorin I and oligosaccharide transferase 48 (OST48). Their presence in the PLC was confirmed by Western blot, suggesting a physical link between protein degradation pathways and the PLC. Based on the findings I discussed how such a link may ensure efficient generation of MHC class I:peptide complexes for T cell surveillance.
Mechanical response and failure mechanism of 2024 aluminum alloy processed by equal channel angular pressing

Experiments were conducted to investigate the mechanical response and failure mechanism of commercial 2024 aluminum alloy processed by Equal Channel Angular Pressing (ECAP). Microstructure refinement was examined by Transmission Electron Microscope (TEM), and material properties were investigated in terms of tensile properties, work-hardening behavior, the Bauschinger effect, fracture surface morphology and micro-void distribution. The experimental results showed that through the ECAP process, the alloy was refined into ultra fine grained structure with grain size of about 300 nm. The ECAPed samples exhibited much enhanced tensile strength, only slightly reduced overall ductility, and unique work hardening behavior. The Bauschinger effect was improved after ECAP, and the ECAPed material displayed a typical ductile microvoid coalescence fracture mode. Attention should be given to these fundamental properties in future commercial applications of ECAPed materials.
Tending the gardens of citizenship: child protection in Toronto 1880s-1920s

Sparked by several high profile child deaths, Ontario's Child Welfare Reform at the turn of the twenty-first century has resulted in a restructuring of the child protection system. This dissertation uses historical analyses to develop a critical understanding of the Reform. The analyses are influenced by the Foucaultian governmentality approach. Specifically, it explores the transformation of conceptions of human identities, citizenship, and technologies of power, from the threshold of the “social” era to our present “post-social” era. The dissertation examines child protection ideas and practices during the period from the late 1880s to 1920s. It argues that preventing crime and immorality and building a useful and Christian citizenry were the main objectives of child protection. Gardening metaphors were used widely to construct a humanist identity for children as “future citizens” and to promote technologies of parental power which were primarily governmental in Foucault's sense. Cruelty and neglect deviated from the gardening mode of parental power. Child protection workers governed parents' cruelty or bad morals so that parents could in turn govern children properly. The study identifies a range of child protection technologies, also represented by gardening metaphors. Child protection connected the conduct of individuals with issues of societal importance. While the focus of child protection was on individuals' conduct, the “social” mode of thinking allowed a consideration of resource issues in other related areas. The analyses of the early history of child protection are used to understand the recent Reform. Instead of being considered as “future citizens,” today children are constituted as the ideal citizens. The child-citizen discourse accentuates children's rights to personal safety and portrays parents as (potential) criminals. In contrast to the earlier period, the primary objective of current child protection is “keeping kids safe.” This understanding severely limits the kinds of collective actions to be considered. New technologies of risk management and criminal punishment subsume child protection to criminality. These changes reflect the “privatization of citizenship.” The dissertation challenges the tendency of reducing complex structural issues to a matter of children's personal safety.
Analyses of mRNA expression and immunolocalization of bone sialoproteins in mineralized connective tissues

Bone sialoprotein II (BSP) and osteopontin (OPN) are two major non-collagenous proteins synthesized and secreted by osteoblasts and deposited in the bone matrix. Their biological functions in bone formation and mineralization, however, are not well understood. The aim of the studies presented here was to determine the gene expression of BSP and OPN at various developmental stages and to localize the proteins at both light and electron microscopic levels and thereby provide insights into the role of these proteins in formation and remodeling of mineralized connective tissues. Using Northern and in situ hybridization, BSP was found to be expressed at the early stages of bone development. BSP mRNA was specifically detected in osteogenic cells actively forming bone matrix; maximal expression being observed at 21 days gestation in fetal rat mineralized tissues. The hybridization signals diminished with subsequent development and aging with barely detectable levels of BSP mRNA in young adult animal tissues. Immunohistochemical analysis using affinity-purified polyclonal antibodies against porcine BSP and OPN showed that BSP was localized in the mineralized bone matrix, dentin and cementum of developing teeth. Using a high-resolution protein A-gold labeling technique, BSP and OPN were localized at the electron microscopical level to electron dense areas concentrated at the mineralizing front and in cement lines. BSP, in particular, was also associated with ‘crystal ghosts’ that are believed to be the site of mineral crystal formation. OPN, which shows a different developmental pattern of mRNA expression and histological distribution from BSP, was also observed in various mineralized connective tissues, but was more specifically located at sites of osteoclastic resorption. When developmental expression of BSP and OPN was compared with type I collagen, and other major non-collagenous bone proteins, osteonectin, osteocalcin and alkaline phosphatase, distinct patterns were observed for each protein. These studies show that BSP is essentially specific to mineralized connective tissues and is likely to have a role in de novo bone formation, with the potential of acting as a nucleator in hydroxyapatite formation. In comparison, OPN appears to be multifunctional with potential roles in both bone resorption and formation.
Molecular mechanisms underlying the expression of the Caudal homeobox gene Cdx-2 -- role of cyclic AMP in the proglucagon producing endocrine cells

Cdx-2, a multiple functional transcription factor, is expressed in differentiated intestinal epithelia and pancreatic islets. Cdx-2 −/− mice are embryonic lethal, whereas Cdx-2 +/− mutants show multiple malfunctions. However, the expression of proglucagon, an endocrine cell downstream target, appears unaltered in Cdx-2+/− mice. We propose that mechanisms underlying Cdx-2 expression differ in different types of cells. We found that forskolin specifically up-regulated Cdx-2 promoter and endogenous Cdx-2 expression in the proglucagon producing endocrine cell lines, GLUTag, STC-1 and InR1-G9. The activation appeared in a PKA independent manner because the activation: (1) was observed in a PKA-deficient cell line InR1-G9, (2) was not observed by co-transfecting the catalytic subunit of PKA into the GLUTag and InR1-G9 cells, and (3) could not be attenuated by the PKA inhibitor H-89 in the PKA active GLUTag cells. My study provides additional evidence that PKA does not account for all the intracellular functions of cAMP.
Development of solid lipid nanoparticles (SLNs) for enhanced delivery of the protease inhibitor (PI), atazanavir, to human brain endothelial cells

Low brain permeability of protease inhibitors (PIs) can lead to the development HIV-1 infection of the brain as well as antiretroviral drug resistance. The objective of this study was to develop and characterize a lipid nanoparticle system for enhanced brain delivery of atazanavir, using a human brain microvessel endothelial cell line (hCMEC/D3) representative of the blood-brain barrier. Solid lipid nanoparticles (SLNs) were prepared by a thin film hydration technique and analyzed for atazanavir encapsulation efficiency, particle size, morphology, zeta potential and drug release. Cytotoxicity experiments indicate that SLNs exhibit no toxicity in hCMEC/D3 cells up to a concentration corresponding to 200 nM of atazanavir. Nanoparticle delivered atazanavir had a significantly higher accumulation as compared to the aqueous solution of [3 H]-atazanavir. Additionally, Rhodamine-123 delivered by SLNs resulted in higher cellular accumulation. Taken together these data suggest that SLNs could be a promising antiviral drug delivery system to enhance brain uptake.
Arterial repair after balloon angioplasty and stenting: Role of extracellular matrix and adventitial microvessels in the development of intimal hyperplasia and restenosis

The development of restenosis after percutaneous coronary intervention (PCI) is a major limitation of such procedures and is associated with significant cost and morbidity. Although, the role of smooth muscle cells and vascular intima in arterial repair after PCI has been well investigated, limited information is available regarding the function of extracellular matrix (ECM) and vascular adventitia in this repair response. The research presented in this thesis focuses on these two important aspects of arterial repair (i.e. ECM turnover and changes in adventitial microvessels) in an attempt to identify new targets for therapeutic intervention. Although, collagen and elastin accumulation in the vessel wall has been identified as a critical component of the arterial repair response after PCI, therapeutic implications of these changes remain unclear. In view of the antifibrotic effects of cryotherapy application during tissue repair observed in skin and liver, intravascular cryotherapy was applied after balloon angioplasty in rabbit iliac arteries and effects on collagen accumulation and intimal hyperplasia determined at 72 hours and at 10 weeks. Cryotherapy application produced average vessel wall temperature of -26°C (range, -20°C to -45°C). Despite greater lumen areas noted immediately, both collagen content and intimal hyperplasia was increased two-fold in cryotherapy treated arteries compared to balloon only injured arteries. In addition, marked cell loss and morphologic changes in the form of cartilage and bone formation were noted in cryotherapy treated arteries suggesting that contrary to earlier observations in skin and liver tissue, intravascular cryotherapy after angioplasty increased intimal hyperplasia and induced fibrosis and chondro-metaplasia with no beneficial effects on restenosis. Inhibition of collagen accumulation in the arterial wall after PCI may also be achieved by inhibition of platelet derived growth factor (PDGF) and transforming growth factor beta (TGF beta), two profibrotic growth factors with increased expression after arterial injury. Decorin is a small leucine rich proteoglycan with potent in vitro activity against PDGF and TGF beta and demonstrated antifibrotic properties in animal models. Adenoviral mediated decorin overexpression was achieved in a rabbit carotid angioplasty model to investigate the role of decorin in the prevention of restenosis. Decorin overexpression after angioplasty inhibited both collagen content and intimal area at ten weeks compared to placebo (beta-galactosidase transfected) or injured non-transfected controls. These findings suggest a potential therapeutic role of decorin in the prevention of intimal hyperplasia and restenosis after PCI. (Abstract shortened by UMI.).
Human leukocyte antigen supertypes and hepatitis C virus infection

Hypothesis. The alleles encoding human leukocyte antigen (HLA) molecules that present viral epitopes required for effective immune responses should be associated with lower risk of HCV infection. Purpose/design. To determine which HLA supertype alleles (functional allelic groupings) are associated with HCV infection, HLA supertypes and behavioral factors were examined in participants from the Vancouver Injection Drug User Study open cohort, grouped according to HCV serostatus (93 seronegative, 120 seropositive). HCV seronegative participants were followed prospectively for factors associated with seroconversion. Results. No HLA supertypes were associated with HCV seronegativity or decreased seroconversion. Class I HLA supertype B62 was associated with increased HCV seroconversion (HR 2.35, p = 0.02). Individual class II HLA alleles and behavioral factors were associated with HCV serostatus and seroconversion. Conclusions . HLA associations with HCV infection might aid in the identification of epitopes important in HCV infection. For broad population coverage, HLA supertypes should be considered in epitope-based vaccine design.