A Proteomic and Cellular Analysis of Uropods in the Pathogen Entamoeba histolytica

Exposure of Entamoeba histolytica to specific ligands induces cell polarization via the activation of signalling pathways and cytoskeletal elements. The process leads to formation of a protruding pseudopod at the front of the cell and a retracting uropod at the rear. In the present study, we show that the uropod forms during the exposure of trophozoites to serum isolated from humans suffering of amoebiasis. To investigate uropod assembly, we used LC-MS/MS technology to identify protein components in isolated uropod fractions. The galactose/N-acetylgalactosamine lectin, the immunodominant antigen M17 (which is specifically recognized by serum from amoeba-infected persons) and a few other cells adhesion-related molecules were primarily involved. Actin-rich cytoskeleton components, GTPases from the Rac and Rab families, filamin, α-actinin and a newly identified ezrin-moesin-radixin protein were the main factors found to potentially interact with capped receptors. A set of specific cysteine proteases and a serine protease were enriched in isolated uropod fractions. However, biological assays indicated that cysteine proteases are not involved in uropod formation in E. histolytica, a fact in contrast to the situation in human motile immune cells. The surface proteins identified here are testable biomarkers which may be either recognized by the immune system and/or released into the circulation during amoebiasis

Tracing the Pathways of Evaluation Influence: From Theory to Practice

This study sought to explore the ways that evaluation influenced changes in attitudes and actions at the individual and interpersonal levels and the pathways through which this influence occurred, all in a real-world evaluation context. Specifically, Mark & Henry's (2004) proposed model of evaluation influence was used as the framework onto which various components of a completed evaluation were mapped. This was accomplished through mixed-method analyses of secondary data from a federally-funded school district evaluation of Small Learning Communities (SLCs). Survey data yielded potential evaluation outcomes which included indicators of behavioral and cognitive change as a result of evaluation findings and hypothesized pathways leading from one type of outcome to another. A series of logistic regressions were used to predict the likelihood of outcome occurrence. Predictors included characteristics such as school assignment and affiliation, measures of organizational context, and awareness. Qualitative analyses of interview and focus group data supported the quantitative findings and provided more nuanced insight into the emergent outcomes and pathways.Ultimately, the findings showed that the greater an individuals' awareness of the evaluation's findings and the greater their understanding of the SLC program's vision, purpose, and goals as well as their own role and comfort in how their specific part of the program had developed, the greater the odds of both behavioral and cognitive change as a result of those evaluation findings. These outcomes, or indicators of evaluation influence, took place largely at individual and interpersonal levels. Furthermore, the presence of some evaluation outcomes increased the odds of other outcomes occurring, providing supporting evidence for Mark & Henry's hypothesized pathways of evaluation influence.The findings generated from this study contribute to research on evaluation in the areas of use and the broader conception of evaluation influence by bridging the gap between theory and practice though systematic study. This expanded conception of evaluation consequences and influence will likely inform practitioners, guide evaluation practice, and promote a more focused awareness from the user perspective