In vitro study of the efficacy of acrylic bone cement loaded with supplementary amounts of gentamicin: Effect on mechanical properties, antibiotic release, and biofilm formation

Background: Infection remains a severe complication following a total hip replacement. If infection is suspected when revision surgery is being performed, additional gentamicin is often added to the cement on an ad hoc basis in an attempt to reduce the risk of recurrent infection.

Methods and results: In this in vitro study, we determined the effect of incorporating additional gentamicin on the mechanical properties of cement. We also determined the degree of gentamicin release from cement, and also the extent to which biofilms of clinical Staphylococcus spp. isolates form on cement in vitro. When gentamicin was added to unloaded cement (1–4 g), there was a significant reduction in the mechanical performance of the loaded cements compared to unloaded cement. A significant increase in gentamicin release from the cement over 72 h was apparent, with the amount of gentamicin released increasing significantly with each additional 1 g of gentamicin added. When overt infection was modeled, the incorporation of additional gentamicin did result in an initial reduction in bacterial colonization, but this beneficial effect was no longer apparent by 72 h, with the clinical strains forming biofilms on the cements despite the release of high levels of gentamicin.

Interpretation: Our findings indicate that the addition of large amounts of gentamicin to cement is unlikely to eradicate bacteria present as a result of an overt infection of an existing implant, and could result in failure of the prosthetic joint because of a reduction in mechanical performance of the bone cement.

Genetic testing and the relationship between specific and general self-efficacy

The study examined the extent to which variations in health-specific self-efficacy could affect general self-efficacy. In a repeated measures design, 300 participants were administered an efficacy questionnaire, before and after an alleged news report, aimed at increasing or decreasing self-efficacy over genetic-testing decision making. The results found that self-efficacy over testing was significantly reduced after reading the negative news report in those participants who felt personal efficacy over testing decisions was important. Levels of general self-efficacy were also significantly decreased. The findings suggest that being denied control over a specific area of self-efficacy can have a wider impact, with a lack of perceived efficacy over testing decision making adversely impacting on levels of general well-being. The wider implications of this generalization effect and the processes involved in efficacy generalization are discussed.

Efficacy and ethics:An investigation into the role of ethics, legitimacy and power in planning

The main thrust of the article is to consider the role of ethics, legitimacy, power and evidence-based policy in planning practice. The laboratory for the investigation is provided by developments in policymaking and implementation in the jurisdiction of Northern Ireland. In this context, each of the key themes is developed to establish a conceptual framework and the emerging issues are subsequently explored in an empirical investigation which deals with policy formulation and implementation, enabling lessons to be learnt about the motivations, tactics and strategies of the various participants in the process.

Self-esteem and self-efficacy: Associations with alcohol consumption in a sample of adolescents in Northern Ireland

Cross-sectional and longitudinal studies have reported equivocal findings regarding the association between self-esteem, self-efficacy and adolescent alcohol use. Data were collected from a sample of 11-16-year olds in Northern Ireland (n = 4088) over two consecutive academic years measuring global self-esteem, academic, social and emotional self-efficacy and alcohol involvement. Results showed a domain-specific association between alcohol involvement and self-efficacy, with more problematic alcohol use associated with higher social self-efficacy but lower emotional and academic self-efficacy. Additionally, regression analyses revealed that all self-concept measures significantly predicted drinking group membership. The results are discussed in terms of reported drinking behaviour, interventions with adolescent groups and general development.