An inhibitor specific for the mouse T-cell associated serine proteinase 1 (TSP-1) inhibits the cytolytic potential of cytoplasmic granules but not of intact cytolytic T cells

We have investigated a proteinase inhibitor, designed according to the preferred amino acid sequence that is cleaved by the murine T-cell specific serine proteinase 1 (TSP-1) for its effect on the cytolytic potential of cloned cytotoxic T-cell lines (CTLL) and of cytoplasmic granules, derived from these cells. Pretreatment of effector cells with H-D-Pro-Phe-Arg-chloromethyl-ketone (PFR-CK) prior to the cytotoxicity assay did not result in inhibition of cytolytic activity of three independent CTLL and did not effect their granule-associated TSP-1 activity after extraction with Triton X-100. Furthermore, PFR-CK did not interfere with cytolysis of target cells by CTLL when present for the entire incubation period. In contrast, PFR-CK inhibited in a dose-dependent manner both TSP-1 activity and the hemolytic/cytolytic potential of isolated cytoplasmic granules after their pretreatment with high-salt concentration. We interpret these results to mean that cytolysis of target cells by CTLL involves the granule-associated proteinase TSP-1, which probably becomes active upon exocytosis following effector-target cell interactions.     

“Trees Live on Soil and Sunshine!”- Coexistence of Scientific and Alternative Conception of Tree Assimilation

Successful learning is the integration of new knowledge into existing schemes, leading to an integrated and correct scientific conception. By contrast, the co-existence of scientific and alternative conceptions may indicate a fragmented knowledge profile. Every learner is unique and thus carries an individual set of preconceptions before classroom engagement due to prior experiences. Hence, instructors and teachers have to consider the heterogeneous knowledge profiles of their class when teaching. However, determinants of fragmented knowledge profiles are not well understood yet, which may hamper a development of adapted teaching schemes. We used a questionnaire-based approach to assess conceptual knowledge of tree assimilation and wood synthesis surveying 885 students of four educational levels: 6^th graders, 10^th graders, natural science freshmen and other academic studies freshmen. We analysed the influence of learner’s characteristics such as educational level, age and sex on the coexistence of scientific and alternative conceptions. Within all subsamples well-known alternative conceptions regarding tree assimilation and wood synthesis coexisted with correct scientific ones. For example, students describe trees to be living on “soil and sunshine”, representing scientific knowledge of photosynthesis mingled with an alternative conception of trees eating like animals. Fragmented knowledge profiles occurred in all subsamples, but our models showed that improved education and age foster knowledge integration. Sex had almost no influence on the existing scientific conceptions and evolution of knowledge integration. Consequently, complex biological issues such as tree assimilation and wood synthesis need specific support e.g. through repeated learning units in class- and seminar-rooms in order to help especially young students to handle and overcome common alternative conceptions and appropriately integrate scientific conceptions into their knowledge profile.     

Can Schools Support HIV/AIDS-Affected Children? Exploring the ‘Ethic of Care’ amongst Rural Zimbabwean Teachers

How realistic is the international policy emphasis on schools ‘substituting for families’ of HIV/AIDS-affected children? We explore the ethic of care in Zimbabwean schools to highlight the poor fit between the western caring schools literature and daily realities of schools in different material and cultural contexts. Interviews and focus groups were conducted with 44 teachers and 55 community members, analysed in light of a companion study of HIV/AIDS-affected pupils’ own accounts of their care-related experiences. We conceptualise schools as spaces of engagement between groups with diverse needs and interests (teachers, pupils and surrounding community members), with attention to the pathways through which extreme adversity impacts on those institutional contexts and social identifications central to giving and receiving care. Whilst teachers were aware of how they might support children, they seldom put these ideas into action. Multiple factors undermined caring teacher-pupil relationships in wider contexts of poverty and political uncertainty: loss of morale from low salaries and falling professional status; the inability of teachers to solve HIV/AIDS-related problems in their own lives; the role of stigma in deterring HIV/AIDS-affected children from disclosing their situations to teachers; authoritarian teacher-learner relations and harsh punishments fuelling pupil fear of teachers; and lack of trust in the wider community. These factors undermined: teacher confidence in their skills and capacity to support affected pupils and motivation to help children with complex problems; solidarity and common purpose amongst teachers, and between teachers and affected children; and effective bridging alliances between schools and their surrounding communities–all hallmarks of HIV-competent communities. We caution against ambitious policy expansions of teachers'' roles without recognition of the personal and social costs of emotional labour, and the need for significant increases in resources and institutional recognition to enable teachers to adopt support roles. We highlight the need for research into how best to create opportunities for teacher recognition in deprived and disorganised institutional settings, and the development of more culturally appropriate notions of caring.     

The Influence of Age and Gender on Skin-Associated Microbial Communities in Urban and Rural Human Populations

Differences in the bacterial community structure associated with 7 skin sites in 71 healthy people over five days showed significant correlations with age, gender, physical skin parameters, and whether participants lived in urban or rural locations in the same city. While body site explained the majority of the variance in bacterial community structure, the composition of the skin-associated bacterial communities were predominantly influenced by whether the participants were living in an urban or rural environment, with a significantly greater relative abundance of Trabulsiella in urban populations. Adults maintained greater overall microbial diversity than adolescents or the elderly, while the intragroup variation among the elderly and rural populations was significantly greater. Skin-associated bacterial community structure and composition could predict whether a sample came from an urban or a rural resident ~5x greater than random.     

Cytosolic phospholipase A2 from U937 cells: size of the functional enzyme by radiation inactivation.

We have studied the cytosolic phospholipase A2 (cPLA2) of human U937 cells by radiation inactivation in order to characterize the functional form of the native enzyme by a method that was independent of the discrepancies observed by SDS-PAGE and cDNA cloning. The Radiation Inactivation Size of cPLA2 was reproducible and gave a value of 76,800-80,100 daltons. We eluted the active enzyme from polyacrylamide-gradient gel electrophoresis at a molecular weight of 77,000, confirming the irradiation result. We conclude that cPLA2 is active as the monomeric enzyme and is composed of a single major functional domain that is sensitive to irradiation.