Long-term (trophic) purinergic signalling: purinoceptors control cell proliferation, differentiation and death

The purinergic signalling system, which uses purines and pyrimidines as chemical transmitters, and purinoceptors as effectors, is deeply rooted in evolution and development and is a pivotal factor in cell communication. The ATP and its derivatives function as a 'danger signal' in the most primitive forms of life. Purinoceptors are extraordinarily widely distributed in all cell types and tissues and they are involved in the regulation of an even more extraordinary number of biological processes. In addition to fast purinergic signalling in neurotransmission, neuromodulation and secretion, there is long-term (trophic) purinergic signalling involving cell proliferation, differentiation, motility and death in the development and regeneration of most systems of the body. In this article, we focus on the latter in the immune/defence system, in stratified epithelia in visceral organs and skin, embryological development, bone formation and resorption, as well as in cancer. Cell Death and Disease (2010) 1, e9; doi:10.1038/cddis.2009.11; published online 14 January 201

Bone Mineral Density in HIV-Negative Men Participating in a Tenofovir Pre-Exposure Prophylaxis Randomized Clinical Trial in San Francisco

Pre-exposure prophylaxis (PrEP) trials are evaluating regimens containing tenofovir-disoproxil fumarate (TDF) for HIV prevention. We determined the baseline prevalence of low bone mineral density (BMD) and the effect of TDF on BMD in men who have sex with men (MSM) in a PrEP trial in San Francisco.We evaluated 1) the prevalence of low BMD using Dual Energy X-ray Absorptiometry (DEXA) in a baseline cohort of 210 HIV-uninfected MSM who screened for a randomized clinical trial of daily TDF vs. placebo, and 2) the effects of TDF on BMD in a longitudinal cohort of 184 enrolled men. Half began study drug after a 9-month delay to evaluate changes in risk behavior associated with pill-use. At baseline, 20 participants (10%) had low BMD (Z score≤-2.0 at the L2-L4 spine, total hip, or femoral neck). Low BMD was associated with amphetamine (OR = 5.86, 95% CI 1.70-20.20) and inhalant (OR = 4.57, 95% CI 1.32-15.81) use; men taking multivitamins, calcium, or vitamin D were less likely to have low BMD at baseline (OR = 0.26, 95% CI 0.10-0.71). In the longitudinal analysis, there was a 1.1% net decrease in mean BMD in the TDF vs. the pre-treatment/placebo group at the femoral neck (95% CI 0.4-1.9%), 0.8% net decline at the total hip (95% CI 0.3-1.3%), and 0.7% at the L2-L4 spine (95% CI -0.1-1.5%). At 24 months, 13% vs. 6% of participants experienced >5% BMD loss at the femoral neck in the TDF vs. placebo groups (p = 0.13).Ten percent of HIV-negative MSM had low BMD at baseline. TDF use resulted in a small but statistically significant decline in BMD at the total hip and femoral neck. Larger studies with longer follow-up are needed to determine the trajectory of BMD changes and any association with clinical fractures.ClinicalTrials.gov: NCT00131677

NMR-based metabolic characterization of chicken tissues and biofluids: a model for avian research

Introduction Poultry is one of the most consumed meat in the world and its related industry is always looking for ways to improve animal welfare and productivity. It is therefore essential to understand the metabolic response of the chicken to new feed formulas, various supplements, infections and treatments. Objectives As a basis for future research investigating the impact of diet and infections on chicken’s metabolism, we established a high-resolution proton nuclear magnetic resonance (NMR)-based metabolic atlas of the healthy chicken (Gallus gallus). Methods Metabolic extractions were performed prior to 1H-NMR and 2D NMR spectra acquisition on twelve biological matrices: liver, kidney, spleen, plasma, egg yolk and white, colon, caecum, faecal water, ileum, pectoral muscle and brain of 6 chickens. Metabolic profiles were then exhaustively characterized. Results Nearly 80 metabolites were identified. A cross-comparison of these matrices was performed to determine metabolic variations between and within each section and highlighted that only eight core metabolites were systematically found in every matrice. Conclusion This work constitutes a database for future NMR-based metabolomic investigations in relation to avian production and health

Monitoring the newly qualified nurses in Sweden: the Longitudinal Analysis of Nursing Education (LANE) study

BACKGROUND: The Longitudinal Analysis of Nursing Education (LANE) study was initiated in 2002, with the aim of longitudinally examining a wide variety of individual and work-related variables related to psychological and physical health, as well as rates of employee and occupational turnover, and professional development among nursing students in the process of becoming registered nurses and entering working life. The aim of this paper is to present the LANE study, to estimate representativeness and analyse response rates over time, and also to describe common career pathways and life transitions during the first years of working life. METHODS: Three Swedish national cohorts of nursing students on university degree programmes were recruited to constitute the cohorts. Of 6138 students who were eligible for participation, a total of 4316 consented to participate and responded at baseline (response rate 70%). The cohorts will be followed prospectively for at least three years of their working life. RESULTS: Sociodemographic data in the cohorts were found to be close to population data, as point estimates only differed by 0-3% from population values. Response rates were found to decline somewhat across time, and this decrease was present in all analysed subgroups. During the first year after graduation, nearly all participants had qualified as nurses and had later also held nursing positions. The most common reason for not working was due to maternity leave. About 10% of the cohorts who graduated in 2002 and 2004 intended to leave the profession one year after graduating, and among those who graduated in 2006 the figure was almost twice as high. Intention to leave the profession was more common among young nurses. In the cohort who graduated in 2002, nearly every fifth registered nurse continued to further higher educational training within the health professions. Moreover, in this cohort, about 2% of the participants had left the nursing profession five years after graduating. CONCLUSION: Both high response rates and professional retention imply a potential for a thorough analysis of professional practice and occupational health

Relative contribution of Rill/Interrill and Gully/Channel erosion to small reservoir siltation in Mediterranean environments

International audienceReservoir siltation because of water erosion is an important environmental issue in Mediterranean countries where storage of clear surface water is crucial for their economic and agricultural development. The high density of gully systems observed in Mediterranean regions raises the question of their contribution to reservoir siltation. In this context, this study quantified the absolute and relative contributions of rill/interrill and gully/channel erosion in sediment accumulation at the outlet of small Tunisian catchments (0·1–10 km$^2$) during the last 15 years (1995–2010). To this end, a fingerprinting method based on measurements of caesium‐137 and total organic carbon combined with long‐term field monitoring of catchment sediment yield was applied to five catchments in order to cover the diversity of environmental conditions found along the Tunisian Ridge and in the Cape Bon region. Results showed the very large variability of erosion processes among the selected catchments, with rill/interrill erosion contributions to sediment accumulated in outlet reservoirs ranging from 20 to 80%. Overall, rill/interrill erosion was the dominant process controlling reservoir siltation in three catchments whereas gully/channel erosion dominated in the other two catchments. We identified the presence of marly gypsum substrates and the proportion of catchment surface covered by soil management/conservation measures as the main drivers of erosion process variability at the catchment scale. These results provided a sound basis to propose guidelines for erosion mitigation in these Mediterranean environments and suggested to apply models simulating both rill/interrill and gully/channel erosion in catchments of the region