999 resultados para Y. pestis


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In this project, antigen-containing microspheres were produced using a range of biodegradable polymers by single and double emulsion solvent evaporation and spray drying techniques. The proteins used in this study were mainly BSA, tetanus toxoid, F1 and V, Y. pestis subunit vaccines and the cytokine, interferon-gamma. The polymer chosen for use in the vaccine preparation will directly determine the characteristics of the formulation. Full in vitro analysis of the preparations was carried out, including surface hydrophobicity and drug release profiles. The influence of the surfactants employed on microsphere surface hydrophobicity was demonstrated. Preparations produced with polyhydroxybutyrate and poly(DTH carbonate) polymers were also shown to be more hydrophobic than PLA microspheres, which may enhance particle uptake by antigen presenting cells and Peyer's patches. Systematic immunisation with microspheres with a range of properties showed differences in the time course and extent of the immune response generated, which would allow optimisation of the dosing schedule to provide maximal response in a single dose preparation. Both systematic and mucosal responses were induced following oral delivery of microencapsulated tetanus toxoid indicating that the encapsulation of the antigen into a microsphere preparation provides protection in the gut and allows targeting of the mucosal-associated lymphoid tissue. Co-encapsulation of adjuvants for further enhancement of immune response was also carried out and the effect on loading and release pattern assessed. Co-encapsulated F1 and interferon-gamma was administered i.p. and the immune responses compared with singly encapsulated and free subunit antigen.

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Topoisomerase inhibitors are effective for antibacterial and anticancer therapy because they can lead to the accumulation of the intermediate DNA cleavage complex formed by the topoisomerase enzymes, which trigger cell death. Here we report the application of a novel enzyme-based high-throughput screening assay to identify natural product extracts that can lead to increased accumulation of the DNA cleavage complex formed by recombinant Yersinia pestistopoisomerase I as part of a larger effort to identify new antibacterial compounds. Further characterization and fractionation of the screening positives from the primary assay led to the discovery of a depside, anziaic acid, from the lichen Hypotrachyna sp. as an inhibitor for both Y. pestis and Escherichia colitopoisomerase I. In in vitro assays, anziaic acid exhibits antibacterial activity against Bacillus subtilis and a membrane permeable strain of E. coli. Anziaic acid was also found to act as an inhibitor of human topoisomerase II but had little effect on human topoisomerase I. This is the first report of a depside with activity as a topoisomerase poison inhibitor and demonstrates the potential of this class of natural products as a source for new antibacterial and anticancer compounds.

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Infection of plant cells by potyviruses induces the formation of cytoplasmic inclusions ranging in size from 200 to 1000 nm. To determine if the ability to form these ordered, insoluble structures is intrinsic to the potyviral cytoplasmic inclusion protein, we have expressed the cytoplasmic inclusion protein from Potato virus Y in tobacco under the control of the chrysanthemum ribulose-1,5-bisphosphate carboxylase small subunit promoter, a highly active, green tissue promoter. No cytoplasmic inclusions were observed in the leaves of transgenic tobacco using transmission electron microscopy, despite being able to clearly visualize these inclusions in Potato virus Y infected tobacco leaves under the same conditions. However, we did observe a wide range of tissue and sub-cellular abnormalities associated with the expression of the Potato virus Y cytoplasmic inclusion protein. These changes included the disruption of normal cell morphology and organization in leaves, mitochondrial and chloroplast internal reorganization, and the formation of atypical lipid accumulations. Despite these significant structural changes, however, transgenic tobacco plants were viable and the results are discussed in the context of potyviral cytoplasmic inclusion protein function.

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In recent times, complaining about the Y Generation and its perceived lack of work ethic has become standard dinner-party conversation amongst Baby Boomers. Discussions in the popular press (Salt, 2008) and amongst some social commentators (Levy, Carroll, Francoeur, & Logue, 2003) indicate that the group labelled Gen Y have distinct and different generational characteristics. Whether or not the differences are clearly delineated on age is still open to discussion but in the introduction to "The Generational Mirage? a pilot study into the perceptions of leadership by Generation X and Y", Levy et al. argue that "the calibre of leadership in competing organisations and the way they value new and existing employees will play a substantial role in attracting or discouraging these workers regardless of generational labels". Kunreuther's (2002) suggests that the difference between younger workers and their older counterparts may have more to do with situational phenomena and their position in the life cycle than deeper generational difference. However this is still an issue for leadership in schools.

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This collection of historical accounts provides diverse perspectives on the structure and culture of the community of researchers who participate in activities of the Australasian Science Education Research Association (ASERA). It describes the formation of the Association, and identifies major changes and challenges for the ever growing and internationalisation of its membership.

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Este libro es una invitación reconceptualizar las maneras de escuchar, conocer, acompañar y educar a los niños desde la primera infancia en un mundo multicultural, cambiante y posmoderno. Los trabajos que lo integran parten de perspectivas que generan nuevas formas de ver, hacer y estar en el mundo, ofrecen una reconstrucción de la psicología del desarrollo y destacan la importancia de la cultura, la etnia, el género y la sexualidad, sin olvidar la historia, la política y el discurso científico.

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Well implemented criterion-referenced assessment (CRA) requires dedicated time and effort, especially in describing realistic expectations of evidence of achievement to students in the form of criteria sheets (or grading rubrics). It is also takes time out of delivering content to teach students how to judge their own work using criteria sheets. In 2007, to engage third year Microbiology students in using criteria sheets for the first time in their degree, we devised an innovative assessment tutorial supported by online resources. We were sceptical of much of the literature that reported ‘agreed’ characteristics of our predominantly gen Y cohort, because of the older ages of the majority of authors. These authors claim gen Y has a propensity for digital media, overconfidence in their own abilities and a collaborative orientation. We rejected this stereotype when developing the tutorial. Evaluations by students were positive and there was no dramatic change to grades for the unit. These results are similar to those in the literature for non gen Y cohorts. This lends support to our claim that giving students control over their own learning, irrespective of their generational label, is worth the time and effort.

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Raman spectroscopy has been used to study the rare earth mineral churchite-(Y) of formula (Y,REE)(PO4) •2H2O. The mineral contains yttrium and depending on the locality, a range of rare earth metals. The Raman spectra of two churchite-(Y) mineral samples from Jáchymov and Medvědín in the Czech Republic were compared with the Raman spectra of churchite-(Y) downloaded from the RRUFF data base. The Raman spectra of churchite-(Y) are characterized by an intense sharp band at 975 cm-1 assigned to the ν1 (PO4)3- symmetric stretching mode. A lower intensity band observed at around 1065 cm-1 is attributed to the ν3 (PO43-) antisymmetric stretching mode. The (PO43-) bending modes are observed at 497 cm-1 (ν2) and 563 cm-1(ν4). Some small differences in the band positions between the four churchite-(Y) samples from four different localities were found. These differences are possible to explain as different compositions of the churchite-(Y) minerals.