[Community-based screening: a motivating experience for drug users]. / Dépister hors les murs d’un centre de dépistage?: une expérience mobilisatrice pour des usagers de drogues.

OBJECTIVES: Hepatitis C virus infection (HCV) is a major public health problem among drug users. Screening for hepatitis C virus in this population is complicated. The aim of the study was to describe a community-based screening experience conducted by the Tours university hospital addiction medicine team. METHODS: Between 2008 and 2010, a free 14-day HCV, hepatitis B virus (HBV) and HIV community-based screening programme was conducted by the addiction medicine and prevention team. A questionnaire collected the main risk factors for transmission of these viruses and the subject's viral serology status. RESULTS: 76% of the 219 screened subjects reported being drug users. HCV prevalence was 20%. Risk factors for HCV infection were exclusive intravenous use and the use of several routes of administration. Among the 30 HCV patients with positive RNA, 83% were followed up. CONCLUSIONS: The prevalence of HCV infection was similar to that reported in the literature for drug users, whereas the number of patients treated and followed up was higher than in the literature. A community-based screening experience facilitated initiation and follow-up of medical care.

Caspase-2(L), caspase-9, and caspase-3 during in vitro maturation and fragmentation of the mouse oocyte.

Several studies have shown that apoptotic pathways control fragmentation of unfertilized ovulated oocyte, induced by doxorubicin. But very few have investigated the basis of this process, from prophase I to later stages. Our results revealed the presence of caspase-2(L), caspase-9, and caspase-3 in their zymogen and cleaved forms in the oocyte before meiosis resumption. Caspase-2(L) and caspase-9 were detected in the nucleus of GV-oocytes in a distribution related to chromatin configuration. The inhibition of caspase activity by Z-VAD-fmk accelerated the transition from metaphase I to metaphase II, and caspase-9 and caspase-3 were detected along the meiotic spindle. Surprisingly, Western blot analysis revealed that the three cleaved caspases were present in similar amounts in healthy and fragmented oocytes and caspase inhibition did not prevent doxorubicin-induced apoptosis. Our results suggest that, if cleaved, caspases may be dispensable for final oocyte death and they could be involved in regulating the maturation process.

Comparison of the expression patterns of five neural RNA binding proteins in the Xenopus retina.

An increasing body of evidence indicates that gene expression can be modulated by posttranscriptional mechanisms. RNA binding proteins, for instance, control gene expression at many regulatory levels including RNA splicing, transport, stability, and translation. Although numerous RNA binding proteins have been identified, very few have been studied extensively in the context of developmental processes. We focused our study on five neural RNA binding proteins: one Musashi homolog, Nrp-1, one member of the Bruno gene family, BruL-1 (also known as Etr-1), and three members of the ELAV/Hu family, ElrB, ElrC, and ElrD. As an initial step in addressing their function during Xenopus neurogenesis, we used in situ hybridization to determine their expression patterns during retinal development. We found that RNA binding proteins belonging to different families have distinct spatio-temporal expression. These combinatorial expression patterns are reminiscent of previously described cell type-specific expression patterns of transcription factors during retinal development. The distribution of RNA binding proteins within the retina suggests that these regulators of posttranscriptional events may play important roles in multiple steps of retinogenesis.

Retinal stem cells in vertebrates: parallels and divergences.

During the development of the nervous system, after a given number of divisions, progenitors exit the cell cycle and differentiate as neurons or glial cells. Some cells however do not obey this general rule and persist in a progenitor state. These cells, called stem cells, have the ability to self-renew and to generate different lineages. Understanding the mechanisms that allow stem cells to "resist" differentiating stimuli is currently one of the most fascinating research areas for biologists. The amphibian and fish retinas, known to contain stem cell populations, have been pioneering models for neural stem cell research. The Xenopus retina enabled the characterization of the genetic processes that occur in the path from a pluripotent stem cell to a committed progenitor to a differentiated neuron. More recently, the discovery that avian and mammalian retinas also contain stem cell populations, has contributed to the definitive view of the adult nervous system of upper vertebrates as a more dynamic and plastic structure than previously thought. This has attracted the attention of clinicians who are attempting to employ stem cells for transplantation into damaged tissue. Research in this area is promising and will represent a key instrument in the fight against blindness and retinal dystrophies. In this review, we will focus primarily on describing the main characteristics of various retinal stem cell populations, highlighting their divergences during evolution, and their potential for retinal cell transplantation. We will also give an overview of the signaling cascades that could modulate their potential and plasticity.