Real-time imaging of novel spatial and temporal responses to photodynamic stress.

Cells subjected to various forms of stress have been shown to induce bystander responses in nontargeted cells, thus extending the stress response to a larger population. However, the mechanism(s) of bystander responses remains to be clearly identified, particularly for photodynamic stress. Oxidative stress and cell viability were studied on the spatial and temporal levels after photodynamic targeting of a subpopulation of EMT6 murine mammary cancer cells in a multiwell plate by computerized time-lapse fluorescence microscopy. In the targeted population a dose-dependent loss of cell viability was observed in accordance with increased oxidative stress. This was accompanied by increased oxidative stress in bystander populations but on different time scales, reaching a maximum more rapidly in targeted cells. Treatment with extracellular catalase, or the NADPH oxidase inhibitor diphenyleneiodinium, decreased production of reactive oxygen species (ROS) in both populations. These effects are ascribed to photodynamic activation of NADPH-oxidase in the targeted cells, resulting in a rapid burst of ROS formation with hydrogen peroxide acting as the signaling molecule responsible for initiation of these photodynamic bystander responses. The consequences of increased oxidative stress in bystander cells should be considered in the overall framework of photodynamic stress.

A healthy settings framework: an evaluation and comparison of midwives' responses to addressing domestic violence

Objectives: to compare and contrast how midwives working in either hospital- or community-based settings address domestic violence by evaluating their views on: prevalence of domestic violence; their role in addressing domestic violence; the acceptability of routine enquiry; and barriers encountered in asking clients questions about violence and abuse in pregnancy. Design: a postal survey questionnaire. Setting: Northern Ireland. Study population: 983 hospital and community midwives. Findings: overall, 488 midwives returned a completed questionnaire; a 57% response rate. Comparisons were made using descriptive, inferential statistics and cross-tabulation. Although there were significant differences between hospital- and community-based midwives in relation to domestic violence, both groups of midwives tended to underestimate its prevalence. Key conclusions: the findings suggest that midwives per se identify and respond to a fraction of the cases of domestic abuse in pregnancy, due to lack of confidence, education and training. This reinforces the need for both hospital and community midwives to gain further confidence and an understanding of the many psychosocial factors that surround domestic violence. Implications for practice: healthy settings theory can be used effectively to identify good practice with women who experience domestic violence. Effective investment for health care requires the gaps between hospital- and community-based practice to be bridged, and for work to be integrated.

Echinostoma caproni: Differential tegumental responses to growth in compatible and less compatible hosts

The topography of the tegument of Echinostoma caproni adults collected from high (mice) and low (rats) compatible hosts was compared by SEM. In the oral (OS) and the ventral sucker (VS) areas, a worm age-host species interaction was found with regard to the density of spines. There was a decrease in the density of spines in the adults collected from mice, whereas an increase occurred in the OS area in worms from rats over time. The tegumentary spines in adults from mice became larger and blunter. Some spines from the VS area in adults from mice at 4 wpi were multipointed. The spines of adults from rats were sharper, not covered by the tegument and no multipointed spines were observed. We detected a greater level of actin gene expression in the adults collected from rats. These facts suggest that the low compatible host induces an increased turnover of tegumentary spines. (C) 2010 Elsevier Inc. All rights reserved.

Aggressive responses to broadband trills are related to subsequent pairing success in nightingales

In sexually selected signals, distinct components often have specific signal value in mate choice or male-male competition. In songbirds, structural song traits such as trills, that is, a series of repetitive notes, can be important in female choice. However, little is known about their signal value in male-male interactions. Here, we investigated the hypothesis that males assess the competitive abilities of rivals based on the use and performance of rapid broadband trills produced within songs. Using a 2-speaker playback experiment, we exposed territorial male nightingales, Luscinia megarhynchos, that differed in their subsequent pairing success, to a simulated vocal interaction between 2 unfamiliar rivals. The singing of the 2 simulated rivals differed in the number of songs containing rapid broadband trills. Subjects responded significantly more strongly to the loudspeaker that broadcast songs containing such trills than to the loudspeaker that broadcast exclusively songs without such trills. Moreover, responses also depended on the fine structure of trills. Males that became paired later in the season significantly increased their response intensity with increasing trill performance, whereas males that remained unpaired responded in the opposite way and decreased their response intensity with increasing trill performance. These results indicate that rapid broadband trills are a signal of aggression and that the nature of the response in vocal interactions reflects aspects of the challenged male's fitness. © The Author 2008. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.


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Repertoire of HLA-DR1-restricted CD4 T cell responses to capsular Caf1 antigen of Y. pestis HLA-transgenic mice

Yersinia pestis is the causative agent of plague, a rapidly fatal infectious disease that has not been eradicated worldwide. The capsular Caf1 protein of Y. pestis is a protective antigen under development as a recombinant vaccine. However, little is known about the specificity of human T cell responses for Caf1. We characterized CD4 T cell epitopes of Caf1 in 'humanized'-HLA-DR1 transgenic mice lacking endogenous MHC class II molecules. Mice were immunized with Caf1 or each of a complete set of overlapping synthetic peptides, and CD4 T cell immunity was measured with respect to proliferative and IFNgamma T cell responses and recognition by a panel of T cell hybridomas, as well as direct determination of binding affinities of Caf1 peptides to purified HLA-DR molecules. Although a number of DR1-restricted epitopes were identified following Caf1 immunization, the response was biased towards a single immunodominant epitope near the C-terminus of Caf1. In addition, potential promiscuous epitopes, including the immunodominant epitope, were identified by their ability to bind multiple common HLA alleles, with implications for the generation of multivalent vaccines against plague for use in humans.

Stable isotope analysis of archived roach (Rutilus rutilus) scales for retrospective study of shallow lake responses to nutrient reduction

1. There is increasing interest in the use of stable isotope analysis of archived materials to study the long-term impacts of lake perturbations, including nutrient manipulation or species invasion. We tested the utility of this approach in a shallow productive lake using the zooplanktivorous early life stages of roach ( Rutilus rutilus), a fish species that is widespread throughout Eurasian lakes.