Binding of Human Milk to Pathogen Receptor DC-SIGN Varies with Bile Salt-Stimulated Lipase (BSSL) Gene Polymorphism

OBJECTIVE: Dendritic cells bind an array of antigens and DC-SIGN has been postulated to act as a receptor for mucosal pathogen transmission. Bile salt-stimulated lipase (BSSL) from human milk potently binds DC-SIGN and blocks DC-SIGN mediated trans-infection of CD4(+) T-lymphocytes with HIV-1. Objective was to study variation in DC-SIGN binding properties and the relation between DC-SIGN binding capacity of milk and BSSL gene polymorphisms. STUDY DESIGN: ELISA and PCR were used to study DC-SIGN binding properties and BSSL exon 11 size variation for human milk derived from 269 different mothers distributed over 4 geographical regions. RESULTS: DC-SIGN binding properties were highly variable for milks derived from different mothers and between samplings from different geographical regions. Differences in DC-SIGN binding were correlated with a genetic polymorphism in BSSL which is related to the number of 11 amino acid repeats at the C-terminus of the protein. CONCLUSION: The observed variation in DC-SIGN binding properties among milk samples may have implications for the risk of mucosal transmission of pathogens during breastfeeding

HIV-1 Disease Progression Is Associated with Bile-Salt Stimulated Lipase (BSSL) Gene Polymorphism

Background: DC-SIGN expressed by dendritic cells captures HIV-1 resulting in trans-infection of CD4+ T-lymphocytes. However, BSSL (bile-salt stimulated lipase) binding to DC-SIGN interferes with HIV-1 capture. DC-SIGN binding properties of BSSL associate with the polymorphic repeated motif of BSSL exon 11. Furthermore, BSSL binds to HIV-1 co-receptor CXCR4. We hypothesized that BSSL modulates HIV-1 disease progression and emergence of CXCR4 using HIV-1 (X4) variants. Results: The relation between BSSL genotype and HIV-1 disease progression and emergence of X4 variants was studied using Kaplan Meier and multivariate Cox proportional hazard analysis in a cohort of HIV-1 infected men having sex with men (n = 334, with n = 130 seroconverters). We analyzed the association of BSSL genotype with set-point viral load and CD4 cell count, both pre-infection and post-infection at viral set-point. The number of repeats in BSSL exon 11 were highly variable ranging from 10 to 18 in seropositive individuals and from 5-17 in HRSN with 16 repeats being dominant (>80% carry at least one allele with 16 repeats). We defined 16 to 18 repeats as high (H) and less than 16 repeats as low (L) repeat numbers. Homozygosity for the high (H) repeat number BSSL genotype (HH) correlated with high CD4 cell numbers prior to infection (p = 0.007). In HIV-1 patients, delayed disease progression was linked to the HH BSSL genotype (RH = 0.462 CI = 0.282-0.757, p = 0.002) as was delayed emergence of X4 variants (RH = 0.525, 95% CI = 0.290-0.953, p = 0.034). The LH BSSL genotype, previously found to be associated with enhanced DC-SIGN binding of human milk, was identified to correlate with accelerated disease progression in our cohort of HIV-1 infected MSM (RH = 0.517, 95% CI = 0.328-0.818, p = 0.005). Conclusion: We identify BSSL as a marker for HIV-1 disease progression and emergence of X4 variants. Additionally, we identified a relation between BSSL genotype and CD4 cell counts prior to infectio

Applying a new concept of embedding qualitative research: An example from a quantitative study of carers of people in later stage dementia

BACKGROUND: Qualitative methods are increasingly included in larger studies to provide a richer understanding of people's experience. This paper explores the potential of using a novel approach to embedded qualitative design as part of an observational study examining the effectiveness of home support for people in later stage dementia in England. The method involved collecting and analysing unsolicited conversational comments made by participants as they completed standardised measures. An evaluation of the method is presented using the voices of participants to illustrate its potential. METHODS: The conversations of 17 carers recruited to an observational study were audio recorded to gather commentary made while completing a structured interview. Data were interrogated using thematic analysis to investigate the feasibility of conducting an embedded qualitative study, the potential richness of the material and participants' reactions to formal questioning and participating in research. RESULTS: The findings revealed that qualitative data were available from this approach. Analysis generated three themes from carers: conflicting carer emotions; the importance of maintaining normality and agency within day-to-day life; and tensions between these desires and making use of formal services. Important issues for carers were revealed establishing the benefit of using the method. The advantages of exploiting unsolicited conversation included enhancing understanding of people's lived experience, reducing participant burden in research and easing the process of data collection. In addition, it provided an opportunity to evaluate individuals' experience of the research process. CONCLUSIONS: The findings demonstrate how unsolicited comments during structured interviews may appear incidental but can reveal important aspects of living with dementia. The method also emphasised methodological challenges for research in dementia, including the influence and impact of the research context. Further research is required to evaluate the method with other groups including people with dementia themselves

Opening the black box of guideline implementation : primary health care nurses' use of a guideline for cardiovascular risk

University of Technology, Sydney. Faculty of Nursing, Midwifery and Health.The implementation of evidence-based clinical practice guidelines in primary health care can substantially improve health promotion, early disease detection and the reduction of the burden of chronic disease. However, the implementation of evidence into clinical practice is a highly complex endeavour that has been said to occur in a 'black box‘, defying easily reached explanations of how it happens in practice. The aim of this study is to explore the 'black box‘ of guideline implementation associated with primary health care nurses‘ use of a guideline that targets high health need populations in a region of New Zealand. The potential for improvement of cardiovascular health overall and the reduction of the marked disparities between Mäori (indigenous people of New Zealand) and non-Mäori drives the imperative to enact the recommendations of the Assessment and Management of Cardiovascular Risk guideline. Primary health care nurses are well positioned at the frontline of healthcare to implement the guideline and an investigation of the realities of their practice as they do so will help to illuminate the contents of this particular 'black box‘. The aim is achieved in two components by: 1. Exploring the complexities of primary health care nurses‘ use of the New Zealand Assessment and Management of Cardiovascular Risk guideline. 2. Employing the Promoting Action on Research Implementation in Health Services (PARiHS) framework to identify the enablers and barriers to guideline implementation in the primary health care setting. Method Both components of this study involve qualitative methods. The first component involves qualitative description utilising focus groups and interviews to explore the perceptions and experiences of a range of primary health care professionals involved in implementing the AMCVR guideline and thematic analysis of data. The second component utilises template analysis of the data, based on the Promoting Action of Research Implementation in Health Services (PARiHS) framework. There are three elements of the PARiHS framework: Evidence, Context and Facilitation. This second component of the study is a systematic analysis of the enablers and barriers encountered by nurses as they implement the AMCVR guideline. Results The first component of the study generated four themes, which together have provided a rich portrait of the realities for nurses as they implemented the guideline. The four themes are self-managing client, everyday nursing practice, developing new relationships in the health team, and impact on health care delivery. The template analysis revealed that there were several enablers and barriers to guideline implementation in relation to Evidence and Context and that Facilitation was not occurring in a planned way. Conclusion Successful guideline implementation demands multidisciplinary, transformational practice development to create an effective workplace culture. Practice development is a powerful approach well suited to supporting primary health care nurses to maximise their practice-based knowledge and skills, and for them to contribute to the development of systems that will meet the information and communication requirements of successful guideline implementation. The imperative to improve cardiovascular health overall and specifically to address Mäori health inequity mandates sustained effort and mobilisation of resources to ensure successful implementation of the AMCVR guideline