Free energy and molecular dynamics calculations for the cubic-tetragonal phase transition in zirconia

The high-temperature cubic-tetragonal phase transition of pure stoichiometric zirconia is studied by molecular dynamics (MD) simulations and within the framework of the Landau theory of phase transformations. The interatomic forces are calculated using an empirical, self-consistent, orthogonal tight-binding (SC-TB) model, which includes atomic polarizabilities up to the quadrupolar level. A first set of standard MD calculations shows that, on increasing temperature, one particular vibrational frequency softens. The temperature evolution of the free energy surfaces around the phase transition is then studied with a second set of calculations. These combine the thermodynamic integration technique with constrained MD simulations. The results seem to support the thesis of a second-order phase transition but with unusual, very anharmonic behaviour above the transition temperature

Predictive habitat suitability models to aid conservation of elasmobranch diversity in the central Mediterranean Sea

Commercial fisheries have dramatically impacted elasmobranch populations worldwide. With high capture and bycatch rates, the abundance of many species is rapidly declining and around a quarter of the world’s sharks and rays are threatened with extinction. At a regional scale this negative trend has also been evidenced in the central Mediterranean Sea, where bottom-trawl fisheries have affected the biomass of certain rays (e.g. Raja clavata) and sharks (e.g. Mustelus spp.). Detailed knowledge of elasmobranch habitat requirements is essential for biodiversity conservation and fisheries management, but this is often hampered by a poor understanding of their spatial ecology. Habitat suitability models were used to investigate the habitat preference of nine elasmobranch species and their overall diversity (number of species) in relation to five environmental predictors (i.e. depth, sea surface temperature, surface salinity, slope and rugosity) in the central Mediterranean Sea. Results showed that depth, seafloor morphology and sea surface temperature were the main drivers for elasmobranch habitat suitability. Predictive distribution maps revealed different species-specific patterns of suitable habitat while high assemblage diversity was predicted in deeper offshore waters (400–800 m depth). This study helps to identify priority conservation areas and diversity hot-spots for rare and endangered elasmobranchs in the Mediterranean Sea

Habitat Selection and Temporal Abundance Fluctuations of Demersal Cartilaginous Species in the Aegean Sea (Eastern Mediterranean)

Predicting the occurrence of keystone top predators in a multispecies marine environment, such as the Mediterranean Sea, can be of considerable value to the long-term sustainable development of the fishing industry and to the protection of biodiversity. We analysed fisheries independent scientific bottom trawl survey data of two of the most abundant cartilaginous fish species (Scyliorhinus canicula, Raja clavata) in the Aegean Sea covering an 11-year sampling period. The current findings revealed a declining trend in R. clavata and S. canicula abundance from the late ′90 s until 2004. Habitats with the higher probability of finding cartilaginous fish present were those located in intermediate waters (depth: 200–400 m). The present results also indicated a preferential species' clustering in specific geographic and bathymetric regions of the Aegean Sea. Depth appeared to be one of the key determining factors for the selection of habitats for all species examined. With cartilaginous fish species being among the more biologically sensitive fish species taken in European marine fisheries, our findings, which are based on a standardized scientific survey, can contribute to the rational exploitation and management of their stocks by providing important information on temporal abundance trends and habitat preferences

Grain Size Control of Tetragonal Zirconia Polycrystals Using the Space Charge Concept

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65680/1/j.1151-2916.1990.tb06449.x.pd

CD19 LYMPHOCYTE PROLIFERATION INDUCED BY Bifidobacterium animalis subsp. lactis IN C57BL/6 MICE EXPERIMENTALLY INFECTED WITH Toxoplasma gondii

Toxoplasmosis is frequently acquired through the oral route by the ingestion of cysts or oocysts of Toxoplasma gondii. Once ingested, the parasites penetrate the intestinal epithelial cells and rapidly disseminate to all organs in the host. During T. gondii infection, the intestinal microbiota plays an important role in stimulating a protective immune response against the parasite. In this sense the use of probiotics is worthy of note since they are live microorganisms that have beneficial effects on the host through stimulation of the immune response that can be important in the control of T. gondii proliferation and dissemination in the host. In the present study, the action of the probiotic Bifidobacterium animalis subsp. lactis was investigated in C57BL/6 mice infected with oocysts of ME49 strain of T. gondii. The probiotic had an immunomodulatory action, inducing CD19 lymphocyte proliferation and consequently increasing anti-T. gondii antibody level.Bifidobacterium animalis subsp. lactisprovided protection in supplemented mice, compared to the control group. In addition, supplemented animals had milder inflammatory process in the small intestine, indicating that the probiotic protects the intestinal mucosa during infection with T. gondii. It was concluded that the probioticB. animalis subsp. lactis induces humoral immune response capable of providing protection against T. gondii infection

Estimating Trends of Population Decline in Long-Lived Marine Species in the Mediterranean Sea Based on Fishers' Perceptions

We conducted interviews of a representative sample of 106 retired fishers in Italy, Spain and Greece, asking specific questions about the trends they perceived in dolphin and shark abundances between 1940 and 1999 (in three 20 year periods) compared to the present abundance. The large marine fauna studied were not target species of the commercial fleet segment interviewed (trawl fishery). The fishers were asked to rank the perceived abundance in each period into qualitative ordinal classes based on two indicators: frequency of sightings and frequency of catches (incidental or intentional) of each taxonomic group. The statistical analysis of the survey results showed that both incidental catches and the sighting frequency of dolphins have decreased significantly over the 60+ years of the study period (except for in Greece due to the recent population increase). This shows that fishers' perceptions are in agreement with the declining population trends detected by scientists. Shark catches were also perceived to have diminished since the early 1940s for all species. Other long-lived Mediterranean marine fauna (monk seals, whales) were at very low levels in the second half of the 20th century and no quantitative data could be obtained. Our study supports the results obtained in the Mediterranean and other seas that show the rapid disappearance (over a few decades) of marine fauna. We show that appropriately designed questionnaires help provide a picture of animal abundance in the past through the valuable perceptions of fishers. This information can be used to complement scientific sources or in some cases be taken as the only information source for establishing population trends in the abundance of sensitive species

Innate Immune Function in Placenta and Cord Blood of Hepatitis C – Seropositive Mother-Infant Dyads

Vertical transmission accounts for the majority of pediatric cases of hepatitis C viral (HCV) infection. In contrast to the adult population who develop persistent viremia in ∼80% of cases following exposure, the rate of mother-to-child transmission (2–6%) is strikingly low. Protection from vertical transmission likely requires the coordination of multiple components of the immune system. Placenta and decidua provide a direct connection between mother and infant. We hypothesized that innate immune responses would differ across the three compartments (decidua, placenta and cord blood) and that hepatitis C exposure would modify innate immunity in these tissues. The study was comprised of HCV-infected and healthy control mother and infant pairs from whom cord blood, placenta and decidua were collected with isolation of mononuclear cells. Multiparameter flow cytometry was performed to assess the phenotype, intracellular cytokine production and cytotoxicity of the cells. In keeping with a model where the maternal-fetal interface provides antiviral protection, we found a gradient in proportional frequencies of NKT and γδ-T cells being higher in placenta than cord blood. Cytotoxicity of NK and NKT cells was enhanced in placenta and placental NKT cytotoxicity was further increased by HCV infection. HCV exposure had multiple effects on innate cells including a decrease in activation markers (CD69, TRAIL and NKp44) on NK cells and a decrease in plasmacytoid dendritic cells in both placenta and cord blood of exposed infants. In summary, the placenta represents an active innate immunological organ that provides antiviral protection against HCV transmission in the majority of cases; the increased incidence in preterm labor previously described in HCV-seropositive mothers may be related to enhanced cytotoxicity of NKT cells

Expression et fonctions du "Transient Receptor potential vanilloid 4" sur les cellules épithéliales intestinales : un nouvel acteur de la réponse inflammatoire

Il a récemment été mis en évidence un rôle potentiel des canaux calciques, dans les Maladies Inflammatoires Chroniques de l'Intestin (MICI). Le rôle d'un membre de la famille des "Transient Receptor Potential Vanilloid " (TRPVs), le TRPV4, qui peut être activé par des dérivés de l'acide arachidonique n'a jamais été étudié dans le contexte des MICI. Nous avons émis l'hypothèse que l'activation de TRPV4, sur les cellules épithéliales intestinales, pourrait entraîner des signaux pro-inflammatoires et participerait donc à l'initiation et/ou au maintien de la réponse inflammatoire intestinale. L'expression de TRPV4, a été révélée sur les cellules épithéliales de patients souffrants ou non de MICI. L'induction de la colite chez la souris, a mis en évidence une augmentation des ARNm de TRPV4 dans les tissus coliques enflammés. Sur deux lignées de cellules épithéliales intestinales humaines, TRPV4 active les voies de signalisation NFkB et AP-1, aboutissant à la libération de cytokines pro-inflammatoires. In vivo, l'administration intracolique de l'agoniste spécifique de TRPV4 chez la souris, provoque une augmentation de la perméabilité paracellulaire et une inflammation. Dans un contexte inflammatoire, de nombreux médiateurs sont libérés, et pourraient réguler les fonctions de TRPV4. Parmi ces médiateurs, nous avons montré que les récepteurs aux protéases (PARs) pouvaient potentialiser la réponse de TRPV4 et à l'inverse le sulfure d'hydrogène (H2S) diminuait son activité. TRPV4 peut donc être considéré comme un nouvel acteur de la réponse inflammatoire intestinale, pouvant être responsable de l'initiation et /ou du maintien de l'inflammation observée au cours des MICI.Recent studies have highlighted a potential role of calcium channels in Inflammatory Bowel Disease (IBD). A recent study, revealed the role of one member of the "Transient Receptor Potential Vanilloid" (TRPV) family, the TRPV4, expressed on neurons, in visceral hypersensitivity. This study suggests a strong, TRPV4 expression, in the colonic mucosa of mice. Different mediators of inflammation can activate TRPV4, so it was important to study its role in intestinal inflammation and potentially on the intestinal epithelial cells. We hypothesized that TRPV4 activation, specifically on intestinal epithelial cells, may result in pro-inflammatory signals, and therefore participate in the initiation and/or maintenance, of the inflammatory response in IBD. TRPV4 expression was strongly detected on epithelial cells from patients with or without IBD. Induction of colitis in mice, showed an increase of TRPV4 mRNA in inflamed colon. In human intestinal epithelial cells lines, TRPV4 activates signalling pathways NF-kB and AP-1, resulting in the release of pro-inflammatory cytokines. In vivo, intracolonic administration of the specific agonist of TRPV4, allowed us to demonstrate that its activation in the colon, causes an increase in paracellular permeability and colitis. In an inflammatory context, many mediators are released and could regulate TRPV4 activity. Among these mediators, we showed that Protease-Activated Receptor (PAR) agonists can potentiate TRPV4 response and conversely hydrogen sulphide (H2S), can decrease TRPV4 activity. Thus, TRPV4 can be considered as a new actor in the intestinal inflammatory response, may be responsible for the initiation and/or maintenance of inflammation observed in IBD

Expression et fonctions du "Transient Receptor Potential Vanilloid 4" sur les cellules épithéliales intestinales (un nouvel acteur de la réponse inflammatoire)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF