77 research outputs found
Espace, Inter/action & Cognition<br />[No spécial de la revue Intellectica 41-42]
No full texthttp://www.intellectica.org/archives/n41_42/n41_42_table.htmL. Mondada : Introduction J. Haviland : Directional Precision in Zinacantec Deictic Gestures : (cognitive ?) preconditions of talk about space A. Spagnolli, L. Gamberini, L. Renò : Mediated Pointing and the Corporeal Field L. Mondada : La constitution de l'origo déictique comme travail interactionnel des participants : une approche praxéologique de la spatialité E. Laurier : Searching for a parking space C. Heath, P. Luff, et M. Sanchez-Svensson : Espaces configurants : le déploiement de l'organisation M. Relieu : Les usages des TIC en situation naturelle : une approche éthnométhodologique de l'hybridation des espaces d'activité B. Conein : Agir dans et sur l'espace de travail avec des objets ordinaires C. Brassac, F. Le Ber : Inscription spatiale d'une activité cognitive collective de représentation de l'espaceO. Söderström : De la mégalopole au split screen. Trois esthétiques urbaines contemporaines F. Rousseaux : Par delà les Connaissances inventées par les informaticiens : les Collections
Polystyrene surface coated with vitamin E modulates human granulocyte adhesion and MMP-9 release
No full textVitamin E (Vit.E, α-tocopherol) is a natural biological antioxidant and antinflammatory agent, which protects cells from the effects of free radicals and inhibits inflammation. For such properties Vit.E has been used to improve the biocompatibility of materials such as cellulose membrane for hemodialysis. In this study granulocytes adhesion and activation have been studied after contact with normal cell culture grade polystyrene (PS) and Vit.E-coated polystyrene (Vit.E 0.1 and 0.3% (v/v)) using optical microscopy, flow cytometry and substrate zymography. Vit.E increased the number of adherent granulocytes both at 0.1% (11470±1064 cells/cm2, P<0.01) and 0.3% (13706±818 cells/cm2, P<0.001) concentration compared to normal PS (5529±692 cells/cm2). The morphology of granulocytes adherent to Vit.E-PS appeared lightly altered and no differences have been observed in their respiratory burst compared to control granulocyte, while matrix metalloproteinase 9 or gelatinase B (MMP-9) release and activation were increased compared to the normal PS samples. Our data indicate that Vit.E-coated surface induced an increase in granulocytes adhesion and MMP-9 release in the absence of the typical oxidative stress, hallmark of granulocytes activation. A possible explanation of the phenomenon is that Vit.E modifies the surface protein adsorption thus increasing cell adhesion and in turn MMP-9 releasing
Textile industry manufacturing by-products induce human melanoma cell proliferation via ERK1/2 activation
No full textOBJECTIVES:
Textiles used to make clothing can represent a source, often ignored, of chemicals potentially noxious to both skin and the whole organism. Among the most frequently produced potentially noxious chemical manufacturing by-products are formaldehyde (FA), nickel (Ni) and hexavalent chromium (Cr); they are of potential clinical interest as all are known to be carcinogenic to humans and to be potent skin sensitizers. The aim of this study was to investigate, in vitro, effects of these potentially dangerous compounds on two different melanoma cell lines. In particular, attention was focused on A375P, a poorly metastatic and low invasive cell line and SK-MEL-28, a highly metastatic cell line.
MATERIALS AND METHODS:
Effects of these compounds was evaluated on A375P and SK-MEL-28 cells. FA (1-5 × 10(-5) m), NiSO4 (10(-6) -10(-3) m), K2 Cr2 O7 (10(-7) -10(-6) m) effects on cell proliferation were evaluated by cell counting, while ERK pathway involvement was evaluated by Western blot analysis.
RESULTS:
Low concentrations of the chemicals, covering a range that corresponds to commonly accepted limits in textile production, induced a significant increase in cell proliferation concomitant with transient activation of phosphorylated ERK expression.
CONCLUSIONS:
Data obtained suggest that increasing attention must be focused on these by-products' potentially harmful effects in chemical manufacturing of clothes and accessories, that remain for long periods of time, in contact with human skin
Which Model for the Italian Interest Rates?
No full textIn the recent years, di usion models for interest rates became very pop- ular. In this paper, we try to do a selection of a suitable di usion model for the Italian interest rates. Our data set is given by the yields on three-month BOT, from 1981 to 2001, for a total of 470 observations. We investigate among stochastic volatility models, paying more attention to a ne models. Estimating di usion models via maximum likelihood,which would lead to e ciency, is usually unfeasible since the transition density is not available. Recently it has been proposed a method of mo- ments which gains full e ciency, hence its name of E cient Method of Moments (EMM); it selects the moments as the scores of an auxiliary model, to be computed via simulation,thus EMM is suitable to di usions whose transition density is un- known, but which are convenient to simulate. The auxiliary model is selected among a family of densities which spans the density space. As a by-product, EMM provides diagnostics which are easy to compute and to interpret. We nd evidence that one- factor models are rejected, while a logarithmic speci cation of the volatility provides the best t to the data, in agreement with the ndings on U.S. data. Moreover, we provide evidence that this model allows a more exible representation of the yield curve.Estimation by simulation; method of moments; stochastic differential equations; diffusions; interest rate term structure; yield curve.
UHMWPE and vitamin E bioactivity: An emerging perspective
No full textUltra-high molecular weight polyethylene (UHMWPE) is a semi crystalline biomaterial widely used in the components for articular prosthesis for its excellent mechanical qualities.
Two major problems limit the UHMWPE prosthesis life-wearing and delamination, both phenomena being mainly due to chemical oxidation of polymer. Wearing causes the release of generated particulate that triggers a macrophage reaction leading to chronic inflammation and osteolysis, while delamination, due to the mechanical stress, macroscopically alters the surfaces. The most diffused method to reduce wearing is UHMWPE molecular cross-linking by high-energy irradiation followed by melting that also reduces polymer fatigue strength. For this reason, the use of vitamin E (a-tocopherol), as an anti-oxidative and biocompatible additive for normal and cross-linked UHMWPE, has been suggested as an alternative method to improve polymer wearing resistance without altering its mechanical strength. This paper describes briefly the rationale of vitamin E as UHMWPE additive and its possible use as an emerging perspective in the orthopaedic field
Nonparametric estimation in models with Lévy type jumps and stochastic volatility
No full textWe introduce a nonparametric estimator of the volatility function in univariate processes with Lévy type jumps and stochastic volatility when we observe the state variable at discrete times. Our results rely on the fact that it is possible to recognize the discontinuous part of the state variable from those squared increments between observations exceeding a suitable threshold. We discuss the implementation of the estimator with high-frequency data
Effect of prostaglandin E2 on PMA-induced macrophage differentiation
No full textMajor trauma such as severe burns and extensive surgery could result in accelerated macrophage differentiation and hyperactivation causing an excessive release of proinflammatory cytokines and prostaglandin E2 (PGE2) with consequent severe impairment of immunologic reactivity. HL-60 cells stimulated with phorbol 12-myristate 13-acetate (PMA) have been used as a model to asses the PGE2 role in the macrophage differentiation observed after major trauma. Cell adhesion, matrix metalloproteinase-9 (MMP-9) and tumor necrosis factor-α (TNF-α) production were measured after 24 h of PMA treatment in the presence of PGE2 (lnM-l μM). PGE2 increased both the PMA-induced cell adhesion and MMP-9 production via EP2/EP4 receptors while it had no effect on the induced TNF-α release. The cAMP/PKA pathway, usually linked to EP2/EP4 activation, was not involved in the phenomenon, suggesting that an alternative signalling pathway could be linked to a PKC-activated enzyme. In fact PGE2 activity was partially inhibited by Wortmannin, a phosphoinositide-3 kinase (PI-3K) inhibitor indicating that PGE2 act as a co-factor able to increase macrophage differentiation in vitro via a PI-3K dependent pathway that could be also involved in the immunosuppression observed in the aftermath of trauma
Discrete-time volatility forecasting with persistent leverage effect and the link with continuous-time volatility modeling
No full textWe first propose a reduced-form model in discrete time for S&P 500 volatility showing that the forecasting performance can be significantly improved by introducing a persistent leverage effect with a long-range dependence similar to that of volatility itself. We also find a strongly significant positive impact of lagged jumps on volatility, which however is absorbed more quickly. We then estimate continuous-time stochastic volatility models that are able to reproduce the statistical features captured by the discrete-time model. We show that a single-factor model driven by a fractional Brownian motion is unable to reproduce the volatility dynamics observed in the data, while a multifactor Markovian model fully replicates the persistence of both volatility and leverage effect. The impact of jumps can be associated with a common jump component in price and volatility
Breaking a Vicious Circle: Lymphangiogenesis as a New Therapeutic Target in Wound Healing
No full textThe lymphatic system is of fundamental importance in maintaining a fluid balance in the body and tissue homeostasis; it drains protein-rich lymph from the interstitial space and facilitates the release of cells that mediate the immune response. When one tissue is damaged, more cells and tissues work to repair the damaged site. Blood and lymph vessels are particularly important for tissue regeneration and healing. Angiogenesis is the process of the formation of new blood vessels and is induced by angiogenic factors such as VEGF-A; VEGF-C/D-induced lymphangiogenesis and both occur simultaneously during wound healing. After the inflammatory phase, lymphatic vessels suppress inflammation by aiding in the drainage of inflammatory mediators; thus, disorders of the lymphatic system often result in chronic and disabling conditions. It has recently been clarified that delayed wound healing, as in diabetes, can occur as a consequence of impaired lymphangiogenesis. In this review, we have highlighted recent advances in understanding the biology underlying lymphangiogenesis and its key role in wound healing, and the possibility of its pharmacological modulation as a novel therapeutic strategy for the treatment of chronic wounds
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