T cell antigen receptor zeta chain down-regulation and impaired in vitro T cell function have been described in cancer and autoimmune and infectious diseases. However, the immunological basis for this phenomenon is unknown. Sustained exposure to antigen and chronic systemic inflammation, factors shared by the various pathologies, might account for this phenomenon. We developed an in vivo experimental system that mimics these conditions and show that sustained exposure of mice to bacterial antigens was sufficient to induce T cell antigen receptor zeta chain down-regulation and impair T cell function, provided an interferon-gamma-dependent T helper type 1 immune response developed. This indicates zeta chain down-regulation could be a physiological response that attenuates an exacerbated immune response. However, it can act as a 'double-edged sword', impairing immune responses to chronic diseases.

Summary It has been observed that in many woody plants the libriform fibres, and in some the fibre tracheids, retain living protoplasts in the entire sapwood. It is suggested, therefore, that the definition of fibres usually given in botanical textbooks, should be changed. From the preliminary study it appears that living protoplasts persist mainly in shrubs and subshrubs. As these life‐forms generally represent the woody vegetation of unfavourable habitats, it may be possible that living fibres are adaptive characters.

The current article presents a new intervention model for intragroup dialogue. Twenty-four Jewish-Israeli undergraduate students underwent a yearlong process to learn about the Israeli–Palestinian conflict, encountered Palestinian narratives, and reflected on the impact of the Palestinian other on their own identity as Jewish-Israelis. In this research we propose that such a process ameliorates identity threats posed by an intergroup conflict on collective identities, encouraging participants to adopt a more complex view of themselves, which validates both narratives of self and “other.” Research was conducted using both qualitative and quantitative methods to evaluate the intervention. Results showed that participants developed an increased capacity for acceptance of both Israeli and Palestinian collective narratives, and demonstrated a greater willingness toward reconciliation, manifested in more readiness to acknowledge responsibility and apologize for past transgressions. Discussion is dedicated to the added value of this model, specifically in relation to intergroup contact approaches to dialogue.

Infusion of parental bone marrow cells into F1 hybrids conditioned by total lymphoid irradiation (TLI) results in chimeras with a high percentage of donor-type cells, and without clinical signs of graft-vs.-host reaction. In these chimeras, a state of tolerance has been shown to be associated with paucity of cytotoxic T lymphocyte percursors (pCTL) reactive with host-type alloantigens. To determine whether the presence of tolerizing alloantigens is essential for maintenance of unresponsiveness, lymphohematopoietic cells obtained from such tolerant chimeras were transferred into supralethally irradiated recipients of two different genotypes: in one case the adoptive recipients were syngeneic with host-type cells, and in the other they were syngeneic with donor-type cells of the original chimeras, thus providing the chimeric cells with a tolerogen-free environment. After "parking" for 4 d in syngeneic donor-type mice, the transferred cells displayed a marked increase in the frequency of pCTL directed against tolerizing alloantigens, whereas a low pCTL frequency directed against the same H-2 target cells was maintained in allogeneic tolerizing-type adoptive recipients. Multiple injections of adoptive donor-type mice with tolerizing-type cells of the original chimera reestablished a low level of cytotoxic precursors. Cytotoxic activity against unrelated alloantigens was independent of the presence of tolerogen-presenting cells in the adoptively transferred mice. Our experimental model suggests that persistence of cells bearing tolerizing alloantigens is an essential requirement for maintenance of previously established tolerance.

No abstract

The research explored the rates and characteristics of exposure to community violence (CV) and its relevance to several sociodemographic factors among a sample of 833 Arab youth aged 14-18 years residing in diverse residential areas in Israel. Data were collected using a self-report questionnaire. The frequency of exposure to CV during the past 12 months correlated significantly with the children's gender. The frequency of witnessing CV during that period was higher than the frequency of personally experiencing CV, and exposure to mild CV incidents during that period was higher than the frequency of exposure to severe CV incidents during the same period, with no significant relationship to sociodemographic factors. Participants reported higher rates of exposure to most CV incidents outside of the neighborhood; however, exposure to beating was higher inside the participants' neighborhood. Moreover, the highest overall rate of exposure to CV was at school. C 2011 Wiley Periodicals, Inc. LITERATURE REVIEWPublic and scholarly interest in exposure to community violence among children and adolescents has been increasing during the last three decades in many countries. Nevertheless, there is a lack of similar research dealing with community violence

No abstract

No abstract