Les souches humaines de rotavirus du groupe A (RVA) reconnaissent des glycannes fucosylés de la famille des Histo-Blood Group Antigens (HBGAs) et des gangliosides via la protéine de capside VP8*. L’interaction avec les gangliosides est essentielle pour l’entrée cellulaire et l’absence de ligands fucosylés dû au polymorphisme génétique des HBGAs est associée à une résistance à la gastroentérite sévère. Nos objectifs étaient de délimiter la contribution des HBGAs et du ganglioside GM1a dans le processus d’infection et d’explorer les conséquences du polymorphisme des HBGAs sur la transmission du virus et l’efficacité des vaccins vivants disponibles.génoty Ces travaux ont permis de montrer la concordance entre la spécificité glycannique des VP8* P[8], génotype le plus fréquent en France, et la sensibilité HBGA-dépendante à la gastroentérite sévère. La reconnaissance des HBGAs par les souches humaines de RVA apparaît donc essentielle pour l’infection symptomatique. Néanmoins, nos résultats suggèrent que l’attachement aux HBGAs correspond à un événement précoce puisqu’il n’est pas nécessaire pour l’infection de cellules peu différenciées par les souches P[8] adaptées à la culture. La contribution du GM1a dans l’infection reste incertaine. Enfin, nous avons montré que la reconnaissance des HBGAs est conservée entre des souches P[8] récentes et anciennes, indiquant que le polymorphisme des HBGAs pourrait contribuer à expliquer le défaut d’efficacité des vaccins dans les régions où la fréquence d’individus n’exprimant pas les ligands fucosylés est élevée. / Human strains of rotavirus A (RVAs) recognize fucosylated glycans of the histo-blood group family (HBGAs) as well as gangliosides through the VP8* protein of their capsid. Interaction with gangliosides is essential for cell entry and lack of fucosylated ligands due to HBGAs genetic polymorphism is associated with resistance to RVA gastroenteritis. Our goals are to delineate the contribution of HBGAs and gangliosides in the infection process and to explore the consequences of HBGAs polymorphisms on the virus transmission and efficacy of the available live vaccines. This study highlighted the concordance between the glycan specificity of P[8] VP8*, the most common genotype in France, and the HBGA-dependant susceptibility to RVA gastroenteritis. The recognition of HBGAs by human RVA strains therefore appears essential to the infection. Yet, our results suggest that HBGA binding corresponds to an early event since it is not required for infection of poorly differentiated cells by cell culture-adapted P[8] strains. The contribution of GM1a on infection remains unclear. Finally, we showed that HBGA recognition is conserved between recent and older P[8] strains, suggesting that HBGAs polymorphism may contribute to explain the low efficacy of vaccines in areas where the frequency of individuals who do not express fucosylated ligands is high.

Made available in DSpace on 2016-08-29T14:12:02Z (GMT). No. of bitstreams: 1 tese_4625_André_Ferreira_Mello.pdf: 1073767 bytes, checksum: 6f3b59f894e176122b4d4e0aabcebf67 (MD5) Previous issue date: 2011-05-05 / O objetivo central deste estudo é analisar as relações entre representação histórica e identidade nacional nos escritos do chileno José Victorino Lastarria. Assim, buscamos rastrear os procedimentos através dos quais o pueblo-nación chileno é transformado no principal sujeito de suas narrativas históricas, a partir de quais dispositivos conceptuais ele procurou tornar a nação chilena uma entidade tangível, conformando, assim, um discurso sobre sua nacionalidade.

The disciplinary anxiety that has emerged between art history and visual culture studies increasingly dominates academic research and institutional practice both in global and South African contexts. The research posed here explores the contested relationship between the discipline of art history and the newly-emerging field of visual culture studies. For, despite the fact that art history has already transformed itself due to ideological pressures, this transformation is evidently no longer sufficient to ward off the visual cultural onslaught. Since the disciplinary boundaries between art history and visual culture studies intersect - or, more aptly, collide - this research examines whether these two fields are complementary or antagonistic endeavours. The proliferation of multitudes of ambiguous visual images, perpetuated by the rise of new media technologies, has complicated image production and consumption. As a result, a critique of all image-making technologies - including art - has gained momentum in light of the increasing entanglement of images with human existence. In particular, this research argues that art history can no longer maintain its allegiance to hierarchical distinctions between images, nor can it rely on traditional art historical methodologies only in its analysis and interpretation of images. This research proposes that art history visual culture studies can critically analyse the ideological functions of images in our postmodern era more appropriately than traditional art history is able to do. / Dissertation (MA (Visual Arts))--University of Pretoria, 2007. / Visual Arts / unrestricted

Healthy tooth formation is crucially dependent on normal development of enamel and dentin. Any deviation from norm could lead to serious effects on the teeth function. Amelogenesis Imperfecta (AI) and Dentinogenesis Imperfecta (DGI) are genetically inherited conditions that affect the teeth formation. Thus is imperative to investigate the genes and proteins that contribute to these conditions. Some of the known proteins that play a role in amelogenesis include AMELOGENIN (AMLEX), KALLIKREIN 4(KLK4), FAMILY WITH SEQUENCE SIMILARITY 83H (FAM83H), WD REPEAT-CONTAINING PROTEIN 72 (WDR72) and DENTIN SIALOPHSOPHPROTEIN (DSPP). The purpose of this research project was to investigate the expression/localization pattern of gene products which are known to be causative for Amelogenesis Imperfecta and Dentinogenesis Imperfecta.The study was carried out using mouse heads which were fixed, demineralized and paraffin-embedded. Samples were then sectioned and immunohistochemical analysis was performed with various enamel/dentin protein antibodies. The data showed the following results: KLK4 showed immunoreactivity mainly in ameloblasts and in the pulp, DSPP showed immunoreactivity in dentin, in the pulp and in the epithelial cells on one location as indicated by the arrow in figure 3 of the tooth cross section, FAM83H has a faint immunoreactivity identified in the ameloblasts, WDR72 showed weak immunoreactivity in the ameloblasts and AMELX showed immunoreactivity on the enamel and the ameloblasts. In conclusion these findings were supported by previous studies and conveyed the validity of IHC experiments in locating these proteins in odontogenic tissues.

No description available.

Hypertension is a risk factor for many cardiovascular and cerebrovascular diseases such as atherosclerosis and stroke. It is therefore important to understand the effect of hypertension on temporal growth and remodeling of arteries. In this study, experimental hypertension was induced in the mini-pig by aortic coarctation. Basilar arteries and aortas were collected for analysis over an eight week period of hypertension with specimens from normotensive animals serving as controls. Changes in mechanical properties of the basilar artery were evaluated by in vitro pressure-diameter tests on intact cylindrical segments at their in situ length. The basilar arteries from hypertensive animals became less distensible, reflecting increases in both structural and material stiffness, compared to their normotensive counterparts. The circumferential stress rapidly returned toward its homeostatic value by increasing the wall thickness within two weeks. Immunohistochemistry, which is capable of illustrating the localization and distribution of protein expression, was performed to examine changes in wall constituents in the aorta. The increased medial thickness observed in hypertensive pigs compared to normotensive pigs was due to hyperplasia of smooth muscle cells (SMCs) and accumulation of extracellular matrix proteins, which were accompanied by the phenotypic modulation of SMCs. The increased interlamellar thickness, collagen fibers, and the thickness of elastic lamina found in the inner media of hypertensive animal may be associated with the gradient of stress decreasing into the outer media. SMC proliferation, if any, was found evenly distributed across the media, however. In cases showing increased proliferation and matrix protein synthesis, the SMC contractile markers were down-regulated whereas the SMC synthetic markers were up-regulated. While the aortic intima appeared normal in the normotensive animals, neointima formation, which may predispose the vessel to atheroma formation, was found in the hypertensive animals. Immunohistochemistry of Hsp47 and procollagen revealed that the endothelial cells (ECs) may produce collagen, specifically type I collagen in response to hypertension and contribute to the thickened intima. In addition, lectin staining for ECs markers and immunostaining for eNOS suggested that endothelial cells may transdifferentiate into intimal SMCs. These findings suggested an alternative role that ECs may play in hypertension-induced atherogenesis.

No description available.

Viruses are common causes of both endemic and epidemic gastroenteritis, infecting millions of people per year, with norovirus, rotavirus and adenovirus-F as the main causative agents, and sapovirus and astrovirus as contributing viruses. These viruses are highly infectious and most severe in the very young, old, or individuals who are immunocompromised. The viral infection usually causes self-limited gastroenteritis, although chronic infection has been observed in highly immunocompromised patients. African and South-East Asian regions are disproportionally affected by diarrhoeal disease. These regions (especially South Africa) are also more severely affected by human immunodeficiency virus (HIV) infections. It has been suggested that immunocompromised individuals may form part of a reservoir for novel virus variants and recombinants. It should be taken into account that not every person is equally susceptible to infection after pathogen exposure and that not all infected persons develop clinical symptoms (Ramani and Giri, 2019). One host genetic factor that can influence susceptibility to enteric infection is the expression of histo-blood group antigens (HBGAs). Histo-blood group antigens are a major group of complex carbohydrates and are determinants of both human and animal ABO blood groups and the Lewis blood group systems, which are distributed in abundance on the mucosal epithelia of the gastrointestinal tract. Histo-blood group antigens have been proven to influence susceptibility to rotavirus and norovirus infections. Saliva, blood and stool specimens (n=205) have previously been collected from children (≤ 5 years of age) hospitalised with gastroenteritis at Kalafong Provincial Tertiary Hospital from June 2016 to December 2017. Follow up stool specimens were then collected six weeks after enrolment when possible. A descriptive questionnaire was completed by each child’s guardian, giving information on age, residential area, HIV status etc. of the participating child. The stool specimens were screened for six gastroenteritis causing viruses (norovirus GI and –GII, rotavirus, sapovirus, astrovirus and adenovirus) by multiplex PCR. Forty-seven percent (96/205) of specimens tested positive for at least one gastroenteritis causing virus. Rotavirus predominated (46/205), followed by norovirus (32/205), adenovirus (15/205), sapovirus (9/205) and astrovirus (3/205). A total of 27/32 norovirus (GI.3, GII.2, GII.3, GII.4, GII.7, GII.12 and GII.21), 44/46 rotavirus (G1P[8], G2P[4], G2P[6], G3P[4], G3P[8], G8P[4], G8P[6], G9P[6] and G9P[8]) and 8/9 sapovirus (GI.1, GI.2, GII.1, GII.4 and GII.8) strains have been genotyped, of which norovirus GII.4 and rotavirus G3P[4] predominated. A total of 46/205 children submitted a follow up stool specimen to be tested. Of the 46 children, 9 tested positive for norovirus infection with initial stool specimen testing. Follow up screening resulted in 13/46 (28%) specimens testing positive for either norovirus GI or GII, with all patients presenting as asymptomatic. After genotyping it was observed that only one of the follow up specimens were identical to the original sequence genotyped, indicating prolonged shedding. FUT2 genotyping of 205/205 children showed a 71%:29% ratio between secretors and non-secretors. Eighty percent (77/96) of the virus-infected children were secretors whereas only 20% (19/96) were non-secretors. Rotavirus (p<0.01) and norovirus GII.4 (p<0.05) specifically were found to be more prevalent in secretors. In this study, no statistical significance was observed in terms of severity of and susceptibility to gastroenteritis viruses between HIV-infected, HIV-exposed uninfected or HIV-uninfected individuals. Histo-blood group phenotyping has resulted in various combinations, with Le(b) being the most prevalent antigen found. Next generation sequencing was unsuccessful. In future, fresh specimens should be considered for testing, with more funding and time for optimisation of this process and to give adequate results. In summary, gastroenteritis is still a leading cause of childhood morbidity and mortality, with all advancements in understanding the disease helping to decrease the impact of it. This study again reinforced the importance of these viruses, as they are circulating in such high abundance. It also reinforced the concept that susceptibility to noro- and rotavirus infection is affected by the secretor status of a person. This could in future help with better understanding the viral infection mechanisms and in turn help with vaccine development and treatment / Dissertation (MSc (Medical Virology))--University of Pretoria, 2020. / Reese Mushrooms / Discovery grant / PRF / Medical Virology / Msc / Unrestricted

Syftet med detta examensarbete var att försöka undersöka hur f-3 lärare ser på yngre barns förmåga att förstå historia samt hur de undervisar för att utveckla elevernas historiska kunskaper och ämnesförståelse. Detta genom att med semistrukturerade intervjuer fråga två lärare om hur de väljer att planera och undervisa i ämnet för att skapa förutsättningar för eleverna att utveckla ett historiemedvetande. Detta tillvägagångssätt gör dock att resultatet inte går att generalisera. Resultatet kan tolkas som att de båda lärarna strävar efter att möta det centrala innehållet för att eleverna ska nå målen inom ämnet och få en så god kronologisk överblick som möjligt. Men att mycket av den utvecklingspsykologiska tanken kring hur yngre barn kan tillägna sig historieundervisningen verkar leva kvar. / The purpose of this thesis was to try to investigate how f-3 teachers view younger children's ability to understand history and how they teach to develop students' historical knowledge and subject understanding. This by using semi-structured interviews to ask two teachers about how they choose to plan and teach the subject in order to create conditions for the students to develop a historical consciousness. However, this approach makes the result impossible to generalize. The result can be interpreted as the two teachers striving to meet the central content in order for the students to achieve the goals within the subject and get as good a chronological overview as possible. But that much of the developmental psychology idea about how younger children can acquire history education seems to remain.

Les métastases hépatiques du cancer colorectal (MHCR) sont fréquentes et sont associées à une mortalité significative. Ces dernières décennies, des progrès thérapeutiques importants ont permis d'en améliorer le pronostic. Plus particulièrement, le rôle des résections hépatiques s'est considérablement élargi dans la maladie métastatique limitée au foie, conduisant à un changement radical dans la prise en charge. Ceci a naturellement eu des répercussions sur l'imagerie, qui doit être très performante au niveau lésionnel, nécessitant des sensibilité et spécificité très élevées. Si les techniques modernes ont permis une amélioration très nette en termes de sensibilité, en particulier grâce aux produits de contraste hépatospécifiques et de l'imagerie pondérée en diffusion, l'amélioration de la spécificité est moins claire et moins bien évaluée. Pourtant, la spécificité est tout aussi importante dans ce contexte, où les erreurs diagnostiques sont coûteuses, avec des chirurgies inutiles en cas de faux positifs, et des résections incomplètes en cas de faux négatifs. Ces deux situations sont accompagnées d'une morbi-mortalité très importante. Le présent travail de thèse va donc explorer de nouvelles pistes dont l'objectif ultime serait d'améliorer la spécificité de l'imagerie des MHCR. La première étude confronte l'apparence des métastases d'origine colorectale en IRM de haute résolution et leur histologie sous-jacente. Cette étude originale démontre que la fibrose tumorale apparait en hypersignal T2 et la nécrose tumorale en hyposignal T2 et hypersignal T1, ce qui va à l'encontre du dogme classique. La seconde étude explore la faisabilité de la fusion d'images IRM/échographie dans l'exploration de lésions hépatiques focales chez des patients ayant un cancer colorectal. Cette étude montre qu'un nombre significatif de lésions ne peuvent être visualisées à l'échographie qu'en utilisant la fusion, ouvrant la voie à une meilleure caractérisation lésionnelle en combinant les atouts de l'échographie et de l'IRM. Enfin, la troisième étude, complétée d'une revue iconographique, analyse le comportement IRM des lésions hépatiques après injection d'un produit de contraste intravasculaire. Elle montre une accumulation progressive du contraste au sein des angiomes, mais pas dans les métastases, conduisant à des apparences très différentes sur la phase tardive. Ceci était aussi observé dans les lésions de petites tailles, ce qui devrait permettre une meilleure spécificité dans les cas difficiles / Colorectal cancer liver metastases (CRCLM) are common and result in significant mortality. During the past decades, important therapeutic advances have improved the prognosis signficantly, especially through a marked expansion of the role of hepatic resections in liverlimited metastatic disease, leading to a radical change in management. This was naturally accompanied by an equally radical change in the imaging paradigm, now centered at the lesion level and not at the patient level, requiring very high sensitivity and specificity. While modern techniques have allowed a significant improvement in terms of sensitivity, especially through the use of hepatospecific contrast agents and diffusion imaging, the benefits in term of specificity are less clear, with only few studies focusing on and reporting the specificity of the techniques. However, specificity is equally important in this context, where diagnostic errors are costly, resulting either in unnecessary surgeries in case of false positives or in incomplete resections in case of false negatives. In this setting, our thesis will examine the results of three studies, which objective is to offer possible solutions to better understand the imaging of metastases and improve the specificity of liver imaging of CRCLM. The first study analyzes the association between high resolution MRI appearance of CRCLM and their underlying histology, showing that tumor fibrosis was in hypersignal on T2 Weighted Imaging while tumor necrosis was in hyposignal on T2 Weighted Imaging and hypersignal on T1 Weighted Imaging, which goes against the classical teaching about these lesions. The second study assesses the feasibility of using an MRI/Ultrasound fusion system in the exploration of liver lesions in patients with colorectal cancer. This study shows that more lesions were detected with ultrasound when using the fusion system, suggesting that a fusion system may allow a better characterization of lesions by combining the complementary information of MRI and ultrasound. Finally, the third study and its accompanying pictorial essay, explored the behavior of liver lesions after injection of an intravascular contrast agent. The main finding of this study was that hemangioma were accumulating the contrast over time while metastases were not, a key differentiating feature. This finding was found even in small lesions, often difficult to diagnose, suggesting that using such contrast in the exploration of liver lesions in patients with CRCLM would result in a higher specificity of the method