The initial education of high school teachers : a critical review of major issues and trends

This paper draws on major research findings in international literature in order to provide a critical review of a number of key issues and trends in the initial education of high school teachers. Firstly, this paper contextualizes the prevalent discourse surrounding the field of initial teacher education (ITE) and explores the effect that this discourse has on the conceptualization of teachers’ work. Secondly, this paper focuses on the debates regarding the most propitious site for the teacher education enterprise, the programme structure for ITE, the field placement or practicum, the relationship between subject study and pedagogy, and the overall effectiveness of teacher education. The paper concludes by considering the new challenges that the field of initial teacher education must confront and the implications of such challenges for the ITE curriculum.peer-reviewe

Efficient Transduction of Vascular Endothelial Cells with Recombinant Adeno-Associated Virus Serotype 1 and 5 Vectors

Recombinant adeno-associated virus (rAAV) has become an attractive tool for gene therapy because of its ability to transduce both dividing and nondividing cells, elicit a limited immune response, and the capacity for imparting long-term transgene expression. Previous studies have utilized rAAV serotype 2 predominantly and found that transduction of vascular cells is relatively inefficient. The purpose of the present study was to evaluate the transduction efficiency of rAAV serotypes 1 through 5 in human and rat aortic endothelial cells (HAEC and RAEC). rAAV vectors with AAV2 inverted terminal repeats containing the human α1-antitrypsin (hAAT) gene were transcapsidated using helper plasmids to provide viral capsids for the AAV1 through 5 serotypes. True type rAAV2 and 5 vectors encoding β-galactosidase or green fluorescence protein were also studied. Infection with rAAV1 resulted in the most efficient transduction in both HAEC and RAEC compared to other serotypes (p < 0.001) at 7 days posttransduction. Interestingly, expression was increased in cells transduced with rAAV5 to levels surpassing rAAV1 by day 14 and 21. Transduction with rAAV1 was completely inhibited by removal of sialic acid with sialidase, while heparin had no effect. These studies are the first demonstration that sialic acid residues are required for rAAV1 transduction in endothelial cells. Transduction of rat aortic segments ex vivo and in vivo demonstrated significant transgene expression in endothelial and smooth muscle cells with rAAV1 and 5 serotype vectors, in comparison to rAAV2. These results suggest the unique potential of rAAV1 and rAAV5-based vectors for vascular-targeted gene-based therapeutic strategies

Uptake and intracellular distribution of ferritin in the rat distal convoluted tubule

Uptake and intracellular distribution of ferritin in the rat distal convoluted tubule. The purpose of this study was to determine the uptake and intracellular distribution of anionic ferritin (AF) and cationic ferritin (CF) in the distal convoluted tubule (DCT) of the rat kidney. Male Sprague-Dawley rats were prepared for micropuncture, and individual distal tubules were perfused with 5 or 10 mg/ml of AF or 0.1 or 0.5 mg/ml of CF in isotonic saline for either 30sec or 3min. The tubules were fixed by perfusion with 6.25% glutaraldehyde either immediately or at different time intervals after exposure to ferritin. Electron microscopy of tubules fixed immediately after perfusion showed no binding of AF to the apical cell membrane, and only traces of AF were observed in small apical structures. In contrast, CF was extensively bound to the apical cell membrane and located in apical vesicles and tubules, and in multivesicular bodies. Occasionally, CF was observed in Golgi vesicles and cisternae. Sixtymin after perfusion with ferritin, traces of AF were present in multivesicular bodies and lysosome-like structures. Thirty and 60min after perfusion, large concentrations of CF were located in multivesicular bodies and lysosome-like bodies. This study reveals that in the DCT, CF is bound to the apical cell membrane and taken up into the tubule cells, whereas only traces of AF are taken up, indicating that the charge of a protein molecule may determine whether or not the protein is reabsorbed by the DCT. The demonstration of CF in the Golgi complex is compatible with the existence of membrane recycling in cells of the DCT.Captation et distribution intracellulaire de la ferritine dans le tube contourné distal du rat. Notre étude a été fit de déterminer la captation et la distribution intracellulaire de la ferritine anionique (AF) et de la ferritine cationique (CF) dans le tube contourné distal (DCT) du rein de rat. Des rats mâles Sprague-Dawley ont été préparés pour des expériences de microponction et des tubes distaux individuels ont été perfusés avec 5 ou 10 mg/ml de l'AF ou 0,1 ou 0,5 mg/ml de la CF dans du soluté salé isotonique pendant 30sec ou 3 mn. Les tubules ont été fixés par perfusion au moyen de glutaraldéhyde à 6,25% soit immédiatement, soit à divers intervalles de temps après l'exposition à la ferritine. La microscopie électronique des tubules fixés immédiatement après perfusion n'a pas montré de liaison de AF à la membrane cellulaire apicale et seules quelques traces de AF ont été détectées dans les petites structures apicales. Au contraire, CF est liée de façon importante à la membrane cellulaire apicale et localisée dans les vésicules et les tubules apicaux et dans les corps multivésiculaires. De façon in constante CF a été observée dans les vésicules et les citernes de Golgi. Soixante minutes après la perfusion de ferritine des traces d'AF étaient encore détectées dans les corps multivésiculaires et les structures semblables aux lysosomes. Trente et 60min après la perfusion, des concentrations importantes de CF ont été détectées dans les corps multivésiculaires et dans les corps semblables à des lysosomes. Notre étude révèle que dans le DCT CF est liée à la membrane cellulaire apicale et captée à l'intérieur des cellules, alors que seules des traces d'AF sont captées, ce qui indique que la charge d'une molécule protéique peut être un facteur qui détermine sa réabsorption par le DCT. La description de CF dans l'appareil de Golgi est compatible avec l'existence d'un recyclage membranaire dans les cellules du DCT