845 resultados para Self and peer review
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The immunodominant, CD8+ cytotoxic T lymphocyte (CTL) response to the HLA-B8-restricted peptide, RAKFKQLL, located in the Epstein–Barr virus immediate-early antigen, BZLF1, is characterized by a diverse T cell receptor (TCR) repertoire. Here, we show that this diversity can be partitioned on the basis of crossreactive cytotoxicity patterns involving the recognition of a self peptide—RSKFRQIV—located in a serine/threonine kinase and a bacterial peptide—RRKYKQII—located in Staphylococcus aureus replication initiation protein. Thus CTL clones that recognized the viral, self, and bacterial peptides expressed a highly restricted αβ TCR phenotype. The CTL clones that recognized viral and self peptides were more oligoclonal, whereas clones that strictly recognized the viral peptide displayed a diverse TCR profile. Interestingly, the self and bacterial peptides equally were substantially less effective than the cognate viral peptide in sensitizing target cell lysis, and also resulted only in a weak reactivation of memory CTLs in limiting dilution assays, whereas the cognate peptide was highly immunogenic. The described crossreactions show that human antiviral, CD8+ CTL responses can be shaped by peptide ligands derived from autoantigens and environmental bacterial antigens, thereby providing a firm structural basis for molecular mimicry involving class I-restricted CTLs in the pathogenesis of autoimmune disease.
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Flowering plants have evolved various genetic mechanisms to circumvent the tendency for self-fertilization created by the close proximity of male and female reproductive organs in a bisexual flower. One such mechanism is gametophytic self-incompatibility, which allows the female reproductive organ, the pistil, to distinguish between self pollen and non-self pollen; self pollen is rejected, whereas non-self pollen is accepted for fertilization. The Solanaceae family has been used as a model to study the molecular and biochemical basis of self/non-self-recognition and self-rejection. Discrimination of self and non-self pollen by the pistil is controlled by a single polymorphic locus, the S locus. The protein products of S alleles in the pistil, S proteins, were initially identified based on their cosegregation with S alleles. S proteins have recently been shown to indeed control the ability of the pistil to recognize and reject self pollen. S proteins are also RNases, and the RNase activity has been shown to be essential for rejection of self pollen, suggesting that the biochemical mechanism of self-rejection involves the cytotoxic action of the RNase activity. S proteins contain various numbers of N-linked glycans, but the carbohydrate moiety has been shown not to be required for the function of S proteins, suggesting that the S allele specificity determinant of S proteins lies in the amino acid sequence. The male component in self-incompatibility interactions, the pollen S gene, has not yet been identified. The possible nature of the pollen S gene product and the possible mechanism by which allele-specific rejection of pollen is accomplished are discussed.
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v.33:no.13(1975)
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More than 10 years ago, it was suggested that sociometry and systematic observation were two potentially useful but under-utilized methods for the study of peers in youth sport (Smith, 2003). Despite this call, the methods used to study peers in sport remain largely focused on athletes' perceptions through questionnaires and interviews. Thus, the purpose of this descriptive study was to investigate the utility of sociometry in relation to sport competence and observed athlete behavior in youth sport. Three adolescent female volleyball teams were videotaped during three practice sessions, and sport competence and sociometric status were assessed using questionnaires. An observational coding system was developed and used to code athlete behaviors and data were compared across sociometric status groups. Results revealed significant differences between sociometric status groups on peer ratings of sport competence, but not on athlete behavior. However, interesting findings emerged with respect to how status groups interacted with teammates and coaches. Thus, sport competence seems to be an important factor in gaining acceptance among youth peer groups. Further, sociometry and behavioral observation appear to be useful techniques that should continue to be employed in the study of peer relations in youth sport.
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Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014
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Bound in a vol. with supplied title: [Austin-Topolovampo railroad documents]
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Mode of access: Internet.
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Mode of access: Internet.
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Published: New York : Leavitt, Trow and Co., 1845- ; The Proprietors, -1850.
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