Sentidos atribuídos pelos alunos do I Ciclo de Ensino Secundário às práticas do recreio da Escola do Cabassango II em Cabinda- Angola

Exportado OPUSMade available in DSpace on 2019-08-12T20:38:36Z (GMT). No. of bitstreams: 1 disserta__o_compilada_celso_chipi_c_pia.pdf: 4006854 bytes, checksum: e5ea6c67fdc8f449b191279f13bf059b (MD5) Previous issue date: 20O propósito deste trabalho é o de verificar o que os alunos pensam e o que fazem no tempo destinado ao recreio/intervalo escolar e de que maneira este tempo/espaço se relaciona com o conjunto das atividades desenvolvidas na escola. Dentre os objetivos delineados, procurou-se mapear e identificar as práticas realizadas no tempo livre e quais são os sentidos e significados atribuídos a elas pelos alunos. Esse estudo procurou investigar o recreio, compreendendo-o como uma prática social, dentro do contexto da Segunda Reforma Educativa em Angola que tem como lema o desenvolvimento de uma escola de qualidade para todos. A investigação teve como pressuposto teórico-metodológico a Abordagem Histórico-cultural de Vygotsky (1934/1987) articulada com a perspectiva da Aprendizagem Situada de Lave e Wenger (1991) e Lave (1990) que entende o ser humano como essencialmente social e que constrói suas aprendizagens imersos em práticas sociais concretas. Este trabalho circunscreve-se no campo das pesquisas qualitativas e na busca pela compreensão dos sentidos e significados que os sujeitos adolescentes atribuem ao tempo livre na escola. Para compreender o fenômeno pesquisado foi necessário um estudo sistematizado da história educacional de Angola, bem como uma imersão ao campo. Os dados foram coletados por meio de entrevistas e gravações em vídeo do cotidiano da escola. Com a análise dos dados foi possível obter evidências de que: (a) a existência ou não do recreio escolar é controversa quando se examina os documentos oficiais, os discursos dos dirigentes das escolas e a organização dos tempos; (b) a relação que os estudantes e professores estabelecem com o tempo vivido na escola é totalmente diversa àquela estabelecida nos documentos oficiais; (c) os sentidos atribuídos pelos alunos ao tempo livre vivenciado na escola faz emergir uma outra escola dentro da escola oficial; (d) a implementação da Reforma educativa no sistema educacional angolano, está em processo de consolidação, demanda infraestrutura adequada e recursos disponíveis. Ao investigarmos a prática do recreio em uma escola de Cabinda, nos deparamos com problemas historicamente constituídos que demandam soluções no âmbito das políticas educacionais que estabeleçam princípios de Higiene, Saúde e Segurança no Ambiente Escolar, para um país em vias de construção.The purpose of this study is to verify what students think and what they do in time for the playground/school break and that way this time/space relates to the set of activities developed at school. Among the goals outlined, sought to map and identify the practices carried out in the free time and what are the senses and meanings assigned to them by the students. This study sought to investigate the playground, understanding it as a social practice, within the context of the second educational reform in Angola, which has as its motto the development of a quality school for all. The investigation had as theoretical-methodological assumption the historical-cultural Approach of Vygotsky (1934-1987) articulated with the perspective of situated Learning Lave and Wenger (1991) and Lave (1990) who understands human beings as essentially social and building their learnings immersed in concrete social practices. This work is limited in the field of qualitative research and the quest for understanding of the senses and meanings that the subjects teens attributed to free time at school. To understand the phenomenon researched was required a systematic study of the educational history of Angola, as well as an immersion into the field. The data were collected through interviews and video recordings of the daily life of the school. With the analysis of the data it was possible to obtain evidence that: (a) the existence or not of the school playground is controversial when it examines the official documents, the speeches of leaders of schools and the Organization of the times; (b) the relationship that students and teachers establish with time lived at school is totally different to that established in the official documents; (c) the meanings assigned by students to free time experienced at school makes emerge another school within the school; (d) the implementation of educational reform in the Angolan education system, is in the process of consolidation, demand adequate infrastructure and resources available. To investigate the practice Cabinda school playground we encounter problems historically constituted that demand solutions within the framework of educational policies that establish principles of hygiene, health, safety in the school environment, to a country in the process of construction

Human T Cell Crosstalk Is Induced by Tumor Membrane Transfer

<div><p>Trogocytosis is a contact-dependent unidirectional transfer of membrane fragments between immune effector cells and their targets, initially detected in T cells following interaction with professional antigen presenting cells (APC). Previously, we have demonstrated that trogocytosis also takes place between melanoma-specific cytotoxic T lymphocytes (CTLs) and their cognate tumors. In the present study, we took this finding a step further, focusing on the ability of melanoma membrane-imprinted CD8⁺ T cells to act as APCs (CD8⁺T-APCs). We demonstrate that, following trogocytosis, CD8⁺T-APCs directly present a variety of melanoma derived peptides to fraternal T cells with the same TCR specificity or to T cells with different TCRs. The resulting T cell-T cell immune synapse leads to (1) Activation of effector CTLs, as determined by proliferation, cytokine secretion and degranulation; (2) Fratricide (killing) of CD8⁺T-APCs by the activated CTLs. Thus, trogocytosis enables cross-reactivity among CD8⁺ T cells with interchanging roles of effectors and APCs. This dual function of tumor-reactive CTLs may hint at their ability to amplify or restrict reactivity against the tumor and participate in modulation of the anti-cancer immune response.</p></div

CD8⁺ T-APCs induce degranulation of effector CTLs with different antigen specificity.

<p>(<b>A, B</b>) CD8⁺ clones with different antigen specificity were used as CD8⁺T-APCs and effector CTLs. Biotinylated effector CTLs were co-cultured with CD8⁺T-APCs, stained with anti-CD107A mAb and streptavidin-allophycocyanin and analyzed by flow cytometry. (<b>A</b>) The gp100_154–162-specific clone 1G2 was used as CD8⁺T-APC for the MART-1_26–35-specific CTL clones (2E2 and 2D11). <b>(B)</b> The MART-1_26–35-specific clones 2E2 and 2D11 were used as CD8⁺T-APC for the gp100_154–162-specific clone (1G2). Numbers in upper right quadrants indicate the percentage of CD107A⁺streptavidin⁺ lymphocytes, gated on the CD8⁺ population (effector CTLs). Data are representative of three independent experiments. (<b>C</b>) Graphic presentation of intra- and inter-clonal T cell cross talk.</p

The effect of CD8⁺T-APCs on effector CTLs is mediated by tumor-derived pMHC.

<p><b>(A)</b> Ova-expressing EG7 and parental EL4 target cell lines (<i>Left column</i>) and target-entrained CD8⁺T-APC (generated following co-culture of OT-I CD8⁺ T cells with designated targets, <i>right column</i>) were labeled with Ova_257–264/H-2Kb-specific mAb (<i>black histogram</i>). <i>Grey histogram</i>, background staining with isotype control antibody. <b>(B)</b> Proliferation of OT-I CD8⁺ T cells stimulated with CD8⁺T-APCs. CFSE-labeled OT-I T cells were left untreated (no target) or co-cultured with the following T-APCs: OT-I CD8⁺ pre-incubated with EL4 (EL4) or OT-I CD8⁺ pre-incubated with EG7 cells (EG7). ConA stimulation was used as positive control (right). <i>Scale bars</i>, proliferating lymphocytes that divided at least twice. <i>Numbers</i>, percentage of dividing CD8⁺ T cells. Data are representative of two independent experiments.</p

CD8⁺T-APCs activate anti-tumor CD8 T cells of the same antigen specificity.

<p><b>(A-C)</b> Cytokine production by effector CTLs in response to activation by T-APCs. <b>(A)</b> DiIC₁₈-labeled CD8⁺T-APCs (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118244#sec002" target="_blank">materials and methods</a>) were incubated for 6 hours with surface-biotinylated effector CTLs. Cytokine-producing effector CTLs were defined based on intracellular IFN-γ or TNF-α staining of CD8⁺streptavidin⁺ lymphocytes. Numbers in upper right quadrants indicate the percentage of IFN-γ ⁺ (upper panel) or TNF-α ⁺ (lower panel) effector CTLs. Labels indicate cells used as targets for CTLs: CTLs co-cultured with 624<i>mel</i> melanoma cells are designated T-APC; CTLs co-cultured with irrelevant M171 melanoma cells are designated non T-APC. <b>(B)</b> Confocal images of cytokine-producing effector CTLs. Calcein AM labeled CD8⁺T-APCs (<i>green</i>, upper panel) or non T-APCs (<i>green</i>, lower panel) were co-cultured for 6 hours with streptavidin-allophycocyanin-stained effector CTLs (<i>red</i>). Intracellular TNF-α production (<i>blue</i>) by effector CTLs is shown. Scale bars are 10 μm (upper panel) and 20 μm (lower panel). <b>(C)</b> Time period that CD8⁺T-APCs activate effector CTLs. Effector CTLs were co-cultured with CD8⁺T-APCs either immediately or 6, 24 and 48 hours after CD8⁺T-APC purification. Data are mean ± SE (n = 3 replicates/group) percentage of IFN-γ ⁺ effector CTLs, gated on CD8⁺ T cells. <b>(D)</b> CD8⁺T-APCs trigger degranulation of effector CTLs. CD8⁺T-APCs were generated as described above (1A) and co-cultured with effector CTLs. Cytolytic activity of T cells was measured by detection of surface CD107A on CD8⁺streptavidin⁺ effector CTLs. Number in upper right quadrants indicates the percentage of CD107A⁺ streptavidin⁺ effector CTLs. Data are representative of at least three independent experiments.</p

CD8⁺T-APC induce secondary trogocytosis by tumor specific CTL.

<p><b>(A, B)</b> CD8⁺T-APCs and non-T-APCs were generated by co-incubation with cognate or irrelevant melanoma, respectively. They were then sorted, labeled with DiIC18 (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118244#sec002" target="_blank">Methods</a>) and co-cultured with surface biotinylated 2C7 or 2E2 clones (effector CTL). The culture was then stained with anti-CD8 antibodies and streptavidin- allophycocyanin, and subjected to flow cytometry. <b>(A)</b> Histograms indicate secondary trogocytosis by the presence of DiIC18 on 2C7 or 2E2 CTLs, gated on CD8⁺streptavidin⁺ populations, following co-culture with CD8⁺T-APC (<i>blue</i>) or non-T-APC (<i>grey</i>). <b>(B)</b> Secondary trogocytosis was measured by presence of DiIC18 on the CD8⁺streptavidin⁺ population (effector CTL) and streptavidin-allophycocyanin on the CD8⁺DiIC18⁺ population (<i>left column</i>, non-T-APC, <i>right column</i>, T-APC). Numbers in upper right quadrants indicate the percentage of DiIC18- stained effector CTL (performing secondary trogocytosis). <b>(C)</b> PKH67-labeled CD8⁺T-APCs (<i>red</i>) were co-cultured with PKH26-labeled effector CTLs (<i>blue</i>). The lymphocytes were co-incubated in a chambered cover-glass and subjected to confocal microscopy. A snapshot series of 8 min is presented. <i>Arrows</i>, transfer of membrane fragments (secondary trogocytosis) from CD8⁺T-APC to CTL. Scale bars, 15 μm. Data are representative of at least five independent experiments (A, B) or of three experiments (C).</p

Assessment of CTL fratricide activity based on detection of cleaved caspase-3.

<p>MART-1- or MUC-1- reactive CTLs were co-cultured with DDAO-SE-tagged CD8⁺T-APCs and non T-APCs, generated by co-incubation of 2E2 cells with 624<i>mel</i> and M171 melanoma cells, respectively. T-APC damage was examined based on detection of intracellular cleaved caspase-3 in the DDAO-SE⁺CD8⁺ population. Numbers in upper right quadrants indicate the percentage of cleaved caspase 3-positive CD8⁺T-APC cells. Data are representative of three independent experiments.</p