Iso-propyl stilbene: a life cycle signal?

Members of the Gram-negative bacterial genus Photorhabdus are all highly insect pathogenic and exist in an obligate symbiosis with the entomopathogenic nematode worm Heterorhabditis. All members of the genus produce the small-molecule 3,5-dihydroxy-4-isopropyl-trans-stilbene (IPS) as part of their secondary metabolism. IPS is a multi-potent compound that has antimicrobial, antifungal, immunomodulatory and anti-cancer activities and also plays an important role in symbiosis with the nematode. In this study we have examined the response of Photorhabdus itself to exogenous ectopic addition of IPS at physiologically relevant concentrations. We observed that the bacteria had a measureable phenotypic response, which included a decrease in bioluminescence and pigment production. This was reflected in changes in its transcriptomic response, in which we reveal a reduction in transcript levels of genes relating to many fundamental cellular processes, such as translation and oxidative phosphorylation. Our observations suggest that IPS plays an important role in the biology of Photorhabdus bacteria, fulfilling roles in quorum sensing, antibiotic-competition advantage and maintenance of the symbiotic developmental cycle.

Implementing a training intervention to support caregivers after stroke: a process evaluation examining the initiation and embedding of programme change.

BACKGROUND: Medical Research Council (MRC) guidance identifies implementation as a key element of the development and evaluation process for complex healthcare interventions. Implementation is itself a complex process involving the mobilization of human, material, and organizational resources to change practice within settings that have pre-existing structures, historical patterns of relationships, and routinized ways of working. Process evaluations enable researchers and clinicians to understand how implementation proceeds and what factors impact on intended program change. A qualitative process evaluation of the pragmatic cluster randomized controlled trial; Training Caregivers after Stroke was conducted to examine how professionals were engaged in the work of delivering training; how they reached and involved caregivers for whom the intervention was most appropriate; how did those on whom training was targeted experience and respond to it. Normalization Process Theory, which focuses attention on implementing and embedding program change, was used as a sensitizing framework to examine selected findings. RESULTS: Contextual factors including organizational history and team relationships, external policy, and service development initiatives, impinged on implementation of the caregiver training program in unintended ways that could not have been predicted through focus on mechanisms of individual and collective action at unit level. Factors that facilitated or impeded the effectiveness of the cascade training model used, whether and how stroke unit teams made sense of and engaged individually and collectively with a complex caregiver training intervention, and what impact these factors had on embedding the intervention in routine stroke unit practice were identified. CONCLUSIONS: Where implementation of complex interventions depends on multiple providers, time needs to be invested in reaching agreement on who will take responsibility for delivery of specific components and in determining how implementation and its effectiveness will be monitored. This goes beyond concern with intervention fidelity; explicit consideration also needs to be given to the implementation process in terms of how program change can be effected at organizational, practice, and service delivery levels. Normalization Process Theory's constructs help identify vulnerable features of implementation processes in respect of the work involved in embedding complex interventions.