Computational quest for understanding the role of astrocyte signaling in synaptic transmission and plasticity.

The complexity of the signaling network that underlies astrocyte-synapse interactions may seem discouraging when tackled from a theoretical perspective. Computational modeling is challenged by the fact that many details remain hitherto unknown and conventional approaches to describe synaptic function are unsuitable to explain experimental observations when astrocytic signaling is taken into account. Supported by experimental evidence is the possibility that astrocytes perform genuine information processing by means of their calcium signaling and are players in the physiological setting of the basal tone of synaptic transmission. Here we consider the plausibility of this scenario from a theoretical perspective, focusing on the modulation of synaptic release probability by the astrocyte and its implications on synaptic plasticity. The analysis of the signaling pathways underlying such modulation refines our notion of tripartite synapse and has profound implications on our understanding of brain function.

Rapid diagnostic tests for the home-based management of malaria, in a high-transmission area.

Rapid diagnostic tests (RDT) are sometimes recommended to improve the home-based management of malaria. The accuracy of an RDT for the detection of clinical malaria and the presence of malarial parasites has recently been evaluated in a high-transmission area of southern Mali. During the same study, the cost-effectiveness of a 'test-and-treat' strategy for the home-based management of malaria (based on an artemisinin-combination therapy) was compared with that of a 'treat-all' strategy. Overall, 301 patients, of all ages, each of whom had been considered a presumptive case of uncomplicated malaria by a village healthworker, were checked with a commercial RDT (Paracheck-Pf). The sensitivity, specificity, and positive and negative predictive values of this test, compared with the results of microscopy and two different definitions of clinical malaria, were then determined. The RDT was found to be 82.9% sensitive (with a 95% confidence interval of 78.0%-87.1%) and 78.9% (63.9%-89.7%) specific compared with the detection of parasites by microscopy. In the detection of clinical malaria, it was 95.2% (91.3%-97.6%) sensitive and 57.4% (48.2%-66.2%) specific compared with a general practitioner's diagnosis of the disease, and 100.0% (94.5%-100.0%) sensitive but only 30.2% (24.8%-36.2%) specific when compared against the fulfillment of the World Health Organization's (2003) research criteria for uncomplicated malaria. Among children aged 0-5 years, the cost of the 'test-and-treat' strategy, per episode, was about twice that of the 'treat-all' (U.S.$1.0. v. U.S.$0.5). In older subjects, however, the two strategies were equally costly (approximately U.S.$2/episode). In conclusion, for children aged 0-5 years in a high-transmission area of sub-Saharan Africa, use of the RDT was not cost-effective compared with the presumptive treatment of malaria with an ACT. In older patients, use of the RDT did not reduce costs. The question remains whether either of the strategies investigated can be made affordable for the affected population.

Ubiquitin-mediated protein degradation and methylation-induced gene silencing cooperate in the inactivation of the INK4/ARF locus in Burkitt lymphoma cell lines.

Burkitt lymphoma is one of the most aggressive tumors affecting humans. Together with the characteristic chromosomal translocation that constitutively activates the c-Myc oncogene, alterations in cellular tumor suppressor pathways are additionally required in order to allow the cells to overcome anti-oncogenic barriers and proliferate in an uncontrolled manner. The INK4a/ARF locus on chromosome 9p21 is considered a safeguard locus since it encodes the two important tumor suppressor proteins, p14 (ARF) and p16 (INK4a) . By regulating the p53 and Rb pathways p14 (ARF) and p16 (INK4a) respectively act as pro-apoptotic and cell cycle inhibitor proteins. The importance of the INK4a/ARF locus has been well documented in several human tumors as well as in Burkitt lymphoma. Although the mechanisms responsible for the transcriptional regulation of the INK4a/ARF locus have been thoroughly characterized, less is known about its posttranscriptional control. In this study we found that p16 (INK4a) and p14 (Arf) are concurrently inactivated in a panel of BL cell lines. We demonstrate that along with the epigenetic silencing of the p16INK4a gene, the complete inactivation of the locus is achieved by the improper turnover of INK4/ARF proteins by the ubiquitin-proteasome system (UPS), as the proteasome inhibitor MG-132 blocks p14 (ARF) degradation and induces a dramatic stabilization of the p16 (INK4a ) protein. We establish that the simultaneous deregulation of both DNA methylation patterns and the ubiquitin-dependent proteolysis system is required to completely inactive the INK4/ARF locus, opening new prospects for the understanding and treatment of Burkitt lymphoma.

Trends in drug consumption and risk of transmission of HIV and hepatitis C virus among injecting drug users in Switzerland, 1993-2006

As a part of the HIV behavioural surveillance system in Switzerland, repeated cross-sectional surveys were conducted in 1993, 1994, 1996, 2000 and 2006 among attenders of all low threshold facilities (LTFs) with needle exchange programmes and/or supervised drug consumption rooms for injection or inhalation in Switzerland. Data were collected in each LTF over five consecutive days, using a questionnaire that was partly completed by an interviewer and partly self administered. The questionnaire was structured around three topics: socio-demographic characteristics, drug consumption, health and risk/preventive behaviour. Analysis was restricted to attenders who had injected drugs during their lifetime (IDUs). Between 1993 and 2006, the median age of IDUs rose by 10 years. IDUs are severely marginalised and their social situation has improved little. The borrowing of used injection equipment (syringe or needle already used by other person) in the last six months decreased (16.5% in 1993, 8.9% in 2006) but stayed stable at around 10% over the past three surveys. Other risk behaviour, such as sharing spoons, cotton or water, was reported more frequently, although also showed a decreasing trend. The reported prevalence of HIV remained fairly stable at around 10% between 1993 and 2006; reported levels of hepatitis C virus (HCV) prevalence were high (56.4% in 2006). In conclusion, the overall decrease in the practice of injection has reduced the potential for transmission of infections. However as HCV prevalence is high this is of particular concern, as the current behaviour of IDUs indicates a potential for further spreading of the infection. Another noteworthy trend is the significant decrease in condom use in the case of paid sex.

Alimentation et transmission mère-enfant

Bien que de nombreux auteurs aient traité, dans la relation mère-enfant, l'importance de l'alimentation, (et donc du rapport à la nourriture) et l'interprétation des troubles qui peuvent en résulter, nous proposons dans cet article de constituer une vérification expérimentale d'une question spécifique: que se transmet-il entre mère et enfant dans le contexte alimentaire ? Au travers d'une recherche multidisciplinaire alliant socio-anthropologie et psychologie, nous avons constitué et étudié un recueil de données couplant représentations socioculturelles, histoires alimentaires personnelles ainsi qu'observations et analyses de la qualité des interactions alimentaires auprès d'une population de mères françaises et leur enfant (sain) âgé de 1 à 2 ans.

Entre l'exemple et l'expérience: de la transmission par la famille d'une tradition à celle d'un ethos religieux

(Résumé de l'ouvrage) Les textes rassemblés dans cet ouvrage proposent diverses approches du phénomène religieux contemporain. Ils en montrent le caractère "flottant", les frontières incertaines. Ils font découvrir de nouveaux lieux vers lesquels s'oriente aujourd'hui une certaine quête de sens et de sacré. Ils pistent les dérives des grandes religions traditionnelles occidentales et les tentatives qu'entreprennent celles-ci pour freiner l'abandon qu'elles enregistrent ou - pire- l'indifférence qu'elle suscitent. Récusant tout autant "la mort de Dieu" que " le retour du religieux", les auteurs soulignent tous la complexité croissante de ce qu'on appelle couramment le religieux.

Use of the chicken lysozyme 5' matrix attachment region to generate high producer CHO cell lines.

Scaffold or matrix attachment region (S/MAR) genetic elements have previously been proposed to insulate transgenes from repressive effects linked to their site of integration within the host cell genome. We have evaluated their use in various stable transfection settings to increase the production of recombinant proteins such as monoclonal antibodies from Chinese hamster ovary (CHO) cell lines. Using the green fluorescent protein coding sequence, we show that S/MAR elements mediate a dual effect on the population of transfected cells. First, S/MAR elements almost fully abolish the occurrence of cell clones that express little transgene that may result from transgene integration in an unfavorable chromosomal environment. Second, they increase the overall expression of the transgene over the whole range of expression levels, allowing the detection of cells with significantly higher levels of transgene expression. An optimal setting was identified as the addition of a S/MAR element both in cis (on the transgene expression vector) and in trans (co-transfected on a separate plasmid). When used to express immunoglobulins, the S/MAR element enabled cell clones with high and stable levels of expression to be isolated following the analysis of a few cell lines generated without transgene amplification procedures.

Antigenic heterogeneity of clones and subclones from human melanoma cell lines demonstrated by a panel of monoclonal antibodies and flow microfluorometry analysis.

Cells from two melanoma cell lines, Me43 and GLL-19, were cloned in methylcellulose cultures and 20 randomly selected colonies from each line were picked up by micromanipulation, expanded in liquid cultures, and considered as clones of the original cell lines. The antigenic cell surface phenotype of these clones defined by panel of 12 monoclonal antibodies (MAb) was analyzed by flow microfluorometry (FMF) using a fluorescence-activated cell sorter (FACS II) and compared with the known stable phenotype of the parent cell line. The antibody panel consisted of eight MAb against melanoma-associated antigens, two MAb against monomorphic determinants of HLA-DR (la) and HLA-ABC, respectively, one MAb against the common acute lymphoblastic leukemia antigen (CALLA) and one MAb against carcinoembryonic antigen used as control. A remarkable heterogeneity in terms of qualitative and quantitative expression of the cell surface antigens studied was observed among and within the different clones. The single-cell origin of the clones was assessed by comparing the clonogenic cell frequency, determined by limiting dilutions in microculture plates, with the cloning efficiency observed in Petri dishes. Both techniques using methylcellulose medium gave the same percentages of growing colonies. Cells from four Me43 clones were recloned in methylcellulose and the phenotype of five randomly selected subclones from each clone was analysed using the same panel of monoclonal antibodies. Each subclone also displayed heterogeneity with individual phenotypes different from that of the original clone and from the parental Me43 cell line. The antigen expression by individual cells in situ within clones was analyzed on frozen sections from colonies using the same panel of MAb and a biotin-avidin immunoperoxidase method. The results confirmed the marked heterogeneity of antigen expression within and among colonies, as indicated by the FMF analysis.

Phylogenetic reconstruction of transmission events from individuals with acute HIV infection: toward more-rigorous epidemiological definitions.

Phylogenetic reconstructions of transmission events from individuals with acute human immunodeficiency virus (HIV) infection are conducted to illustrate this group's heightened infectivity. Varied definitions of acute infection and assumptions about observed phylogenetic clusters may produce misleading results. We conducted a phylogenetic analysis of HIV pol sequences from 165 European patients with estimated infection dates and calculated the difference between dates within clusters. Nine phylogenetic clusters were observed. Comparison of dates within clusters revealed that only 2 could have been generated during acute infection. Previous analyses may have incorrectly assigned transmission events to the acutely HIV infected when they were more likely to have occurred during chronic infection.

Molecular epidemiology reveals long-term changes in HIV type 1 subtype B transmission in Switzerland.

BACKGROUND: Sequence data from resistance testing offer unique opportunities to characterize the structure of human immunodeficiency virus (HIV) infection epidemics. METHODS: We analyzed a representative set of HIV type 1 (HIV-1) subtype B pol sequences from 5700 patients enrolled in the Swiss HIV Cohort Study. We pooled these sequences with the same number of sequences from foreign epidemics, inferred a phylogeny, and identified Swiss transmission clusters as clades having a minimal size of 10 and containing >or=80% Swiss sequences. RESULTS: More than one-half of Swiss patients were included within 60 transmission clusters. Most transmission clusters were significantly dominated by specific transmission routes, which were used to identify the following patient groups: men having sex with men (MSM) (38 transmission clusters; average cluster size, 29 patients) or patients acquiring HIV through heterosexual contact (HETs) and injection drug users (IDUs) (12 transmission clusters; average cluster size, 144 patients). Interestingly, there were no transmission clusters dominated by sequences from HETs only. Although 44% of all HETs who were infected between 1983 and 1986 clustered with injection drug users, this percentage decreased to 18% for 2003-2006 (P<.001), indicating a diminishing role of injection drug users in transmission among HETs over time. CONCLUSIONS: Our analysis suggests (1) the absence of a self-sustaining epidemic of HIV-1 subtype B in HETs in Switzerland and (2) a temporally decreasing clustering of HIV infections in HETs and IDUs.