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Present Work (present + work)
Selected AbstractsThe role of a novel p -phenylen-bis-maleamic acid grafted atactic polypropylene interfacial modifier in polypropylene/mica composites as evidenced by tensile propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009J. M. García-Martínez Abstract Present work is devoted to the study of the tensile behavior of polypropylene (PP)/mica composites with improved interfacial interactions from the matrix side caused by the presence of a p -phenylen-bis-maleamic acid grafted atactic polypropylene (aPP- pPBM) as an interfacial agent. Hence, aPP- pPBM was previously obtained, in our laboratories, by reactive processing in the melt of a by-product (atactic PP) from industrial polymerization reactors. Present article is two-fold, on one hand it has been planned to evidence the so called interfacial effects caused by this novel interfacial agent (aPP- pPBM) yielding better final properties of the heterogeneous system as a whole as revealed by tensile mechanical properties, and on the other to obtain models to forecast the overall behavior of the system. For such purpose, a Box-Wilson experimental design considering the amount of mica particles and of interfacial agent as independent variables was used to obtain polynomials to forecast the behavior of the PP/Mica system in the experimental space scanned. The existence of a critical amount of aPP- pPBM to optimize mechanical properties appears to emerge. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] New reference for the age at childhood onset of growth and secular trend in the timing of puberty in SwedishACTA PAEDIATRICA, Issue 6 2000YX Liu The objectives of the present work were to present a new reference for the age at childhood onset of growth and to investigate the secular trend in the timing of puberty in a community-based normal population in Sweden. A total of 2432 children with longitudinal length/height data from birth to adulthood were used to determine the two measures by visual inspection of the measured attained length/height and the change in growth velocity displayed on a computer-generated infancy-childhood-puberty (ICP) based growth chart. The series represents a sample of normal full-term children born around 1974 in Göteborg, Sweden. We found about 10% of children were delayed (>12 mo of age) in the childhood onset of growth based on the previous reported normal range, i.e. 14% in boys and 8% in girls. Distribution of the age at childhood onset of growth was skewed. The medians were 10 and 9 mo for boys and girls, respectively. After natural logarithmic transformation, the mean and standard deviation (SD) were 2.29 (anti-log 9.9 mo) and 0.226 for boys, 2.23 (anti-log 9.3 mo) and 0.220 for girls, respectively. The 95% normal ranges were 6.3-15.4 and 6.0-14.3 for boys and girls, respectively. The distribution of the timing of PHV was close to the normal distribution. The mean values were 13.5 y for boys and 11.6 y for girls with 1 y SD for both sexes. Conclusion: A downward secular trend in the onset of puberty was clearly shown in the population. The age at childhood onset of growth did not correlate with the timing of puberty (r=,0.01 and 0.05, p > 0.7 and 0.1 in boys and girls, respectively). Normal ranges of the age at childhood onset of growth are in need of revise, as this study indicates. The new reference presented here could be a reliable indicator in further studies. [source] Contamination by nickel, copper and zinc during the handling of euro coinsCONTACT DERMATITIS, Issue 4 2003Paul-Guy Fournier The introduction of the euro has revived interest in the risk of nickel allergy due to the handling of coins. In the present work, the transfer of metallic contamination during the manipulation of coins is examined by means of leaching experiments and manipulation tests. It is shown that pre-existing metallic species present on the surface of the coins are the major source of contamination during manipulation, and that friction inherent to everyday usage contributes predominantly to their transfer to the hands. The comparison of coins as to their relative risks of metal contamination should therefore rely on tests that simulate the friction inherent in everyday human handling. Carrying out such tests with the newly issued 1, and 2, pieces, we find, contrary to long-term leaching measurements, that the euros release less nickel than previously circulated pure-nickel coins, but that this decrease is less pronounced than might have been hoped for on the basis of their surface composition. When the coins are rubbed to a shiny polish before manipulation, contamination of the fingers is reduced by more than a factor of 10. A comparison of coins used in France indicates that the introduction of the common currency has led to a fourfold reduction in contamination by nickel, while causing a 45% increase in contamination by copper. [source] Assessing cytotoxicity of (iron oxide-based) nanoparticles: an overview of different methods exemplified with cationic magnetoliposomesCONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2009Stefaan J. H. Soenen Abstract Iron oxide nanoparticles are the most widely used T2/T2* contrast agents and for biomedical research purposes, one of the main applications is the in vitro labeling of stem or therapeutic cells, allowing them to be subsequently tracked in vivo upon transplantation. To allow this, the nanoparticles used should not show any sign of cytotoxicity and not affect cellular physiology as this could impede normal cell functionality in vivo or lead to undesired side-effects. Assessing the biocompatibility of the nanoparticles has proven to be quite a difficult task. In the present work, a small overview of commonly used assays is presented in order to assess several aspects, such as cell viability, induction of reactive oxygen species, nanoparticle uptake, cellular morphology, cellular proliferation, actin cytoskeleton architecture and differentiation of stem cells. The main focus is on comparing the advantages and disadvantages of the different assays, highlighting several common problems and presenting possible solutions to these problems as well as pointing out the high importance of the relationship between intracellular nanoparticle concentration and cytotoxicity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Numerical Analysis and Simulation Analysis for Space-Time DataCONTRIBUTIONS TO PLASMA PHYSICS, Issue 10 2006M. A. Hassouba Abstract Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio- temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg-Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio-temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space-time data and theoretical simulation space-time results was obtained. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microwave Breakdown Field in a Resonant Spherical CavityCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2006R. Tomala Abstract In the present work, the microwave breakdown threshold in a gas-filled spherical resonator, is determined for the case when the cavity is excited in its lowest order mode, which implies that the microwave field strength depends on both radius and azimuthal angle. A semi-analytical approximation of the breakdown threshold is found using a direct variational approach. The variational predictions are compared with the results of full numerical calculations and demonstrate very good agreement [source] Managers' profile in environmental strategy: a review of the literatureCORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 5 2006Esteban Fernández Abstract Environmental legislation and stakeholders are putting pressure on organizations to change. The role of management is a key factor. The aim of the present work is to determine the key characteristics required of a manager with environmental responsibilities and determine which are the critical aptitudes and attitudes for environmental success through a deep review of the literature. We include three kinds of characteristic: (a) managerial attitude and social influence, (b) individual characteristics (demographic characteristics, capability to perceive strategic opportunities, leadership, individual entrepreneurial ability and international awareness) and (c) organizational characteristics (organizational culture, capability to influence strategy, long-term orientation, organizational structure and demographic characteristics). With this purpose, we have collected and integrated the most relevant contributions of the literature. We have also suggested future research streams: for example, analysis of the interdependences among the diverse dimensions of a manager with environmental responsibilities, analysis of the characteristics typical of external stakeholders that condition the managerial behaviour and other aspects of environmental strategy on which management attitude has an influence. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment. [source] The use of economic, social and environmental indicators as a measure of sustainable development in SpainCORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 2 2006Isabel Gallego Abstract In recent years the concept of corporate social responsibility has gained prominence among academics from a wide range of disciplines. According to the Green Paper issued by the Commission of the European Communities in July 2001, corporate social responsibility is defined as a concept whereby companies integrate social and environmental concerns in their business operations and in their interaction with their stakeholders on a voluntary basis. The problem is how firms have made known the information on corporate social responsibility. With this in mind, we undertook the present work in an attempt to verify empirically how certain Spanish firms present their economic, social and environmental information, how they use the indicators proposed by the Global Reporting Initiative (GRI) that are accepted in all countries and how this information can affect sustainable development. To perform this study we examined some Spanish firms that present economic, social and environmental information according to the GRI framework. Certain relevant conclusions indicate that in Spain in the last few years there has been an increase and an improvement in the information given by firms on economic, social and environmental concerns and that the information most presented by firms has to do with the social indicators related to labour, practices and decent work, strategy and management, non-discrimination, freedom of association, child labour and forced and compulsory labour as well as the environmental indicators related to energy, water, biodiversity and emissions, effluents and waste. This information reveals the great importance afforded in Spain to social and environmental information for sustainable development. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment. [source] Mechanical activation of precursors for nanocrystalline materialsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2003H. Heegn Abstract Nanostructured materials win big scientific interest and increasingly economic meaning through their specific exceptional properties. Precursors that were compacted by pressing and sintering are normally used preparation of materials. In present work, the influence of mechanical activation by grinding on the structure as well as on compacting and sintering behavior of oxides from magnesium, aluminium and silicon has been investigated. Starting materials for each metal oxide differ in microstructure, dispersity, and porosity. The influence of mechanical activation on the destruction of crystalline structure to nanocrystalline, as well as to the amorphous stage and the compaction of powders with nano-particles, as well as structures with nanoscale pores have been compared. The possibilities of the consolidation of nanostructured materials were investigated. The mechanical activation took place in a disc vibration mill. The mechanical activated materials as well as their pressing and their sintering products were characterized by density, particle-sizedistribution, specific surface, pore-structure, microstructure, and crystallite size by X-ray powder diffraction (XRD). The mechanical activation of the model-substances led, in most cases, to an improvement of the compaction properties; thus, this improvement can be achieved with subsequent sintering densities up to 98% of the theoretical density. From these experiments, generalizations transferable to other materials can be made. [source] Myosin localization during meiosis I of crane-fly spermatocytes gives indications about its role in divisionCYTOSKELETON, Issue 2 2003Rosalind V. Silverman-Gavrila Abstract We showed previously that in crane-fly spermatocytes myosin is required for tubulin flux [Silverman-Gavrila and Forer, 2000a: J Cell Sci 113:597,609], and for normal anaphase chromosome movement and contractile ring contraction [Silverman-Gavrila and Forer, 2001: Cell Motil Cytoskeleton 50:180,197]. Neither the identity nor the distribution of myosin(s) were known. In the present work, we used immunofluorescence and confocal microscopy to study myosin during meiosis-I of crane-fly spermatocytes compared to tubulin, actin, and skeletor, a spindle matrix protein, in order to further understand how myosin might function during cell division. Antibodies to myosin II regulatory light chain and myosin II heavy chain gave similar staining patterns, both dependent on stage: myosin is associated with nuclei, asters, centrosomes, chromosomes, spindle microtubules, midbody microtubules, and contractile rings. Myosin and actin colocalization along kinetochore fibers from prometaphase to anaphase are consistent with suggestions that acto-myosin forces in these stages propel kinetochore fibres poleward and trigger tubulin flux in kinetochore fibres, contributing in this way to poleward chromosome movement. Myosin and actin colocalization at the cell equator in cytokinesis, similar to studies in other cells [e.g., Fujiwara and Pollard, 1978: J Cell Biol 77:182,195], supports a role of actin-myosin interactions in contractile ring function. Myosin and skeletor colocalization in prometaphase spindles is consistent with a role of these proteins in spindle formation. After microtubules or actin were disrupted, myosin remained in spindles and contractile rings, suggesting that the presence of myosin in these structures does not require the continued presence of microtubules or actin. BDM (2,3 butanedione, 2 monoxime) treatment that inhibits chromosome movement and cytokinesis also altered myosin distributions in anaphase spindles and contractile rings, consistent with the physiological effects, suggesting also that myosin needs to be active in order to be properly distributed. Cell Motil. Cytoskeleton 55:97,113, 2003. © 2003 Wiley-Liss, Inc. [source] Lactic Acid Chemical Peels as a New Therapeutic Modality in Melasma in Comparison to Jessner's Solution Chemical PeelsDERMATOLOGIC SURGERY, Issue 12 2006KHALIFA E. SHARQUIE MBCHB BACKGROUND Many chemicals have been used in the skin peeling for melasma such as Jessner's solution and glycolic acid. Lactic acid is an ,-hydroxy acid that has not been used before in chemical peeling of melasma. OBJECTIVE The purpose of the present work was to evaluate the efficacy and safety of lactic acid in chemical peeling of melasma in comparison to Jessner's solution chemical peels. METHODS This study was conducted at the Department of Dermatology and Venereology, Baghdad Hospital, in the period between April 2001 and August 2002. Thirty patients with melasma were included in this study. They were mostly of skin type IV according to Fitzpatrick's classification, 26 (86.67%) were women, and 4 (13.33%) were men, with an age range from 18 and 50 years (mean±SD, 33.53±6.96 years). Full clinical examination was done to all patients including Wood's light. The severity of melasma was assessed by MASI (Melasma Area Severity Index). Pure lactic acid full strength (92%, pH 3.5) was used as a new peeling agent on the left side of the face while Jessner's solution was applied to the right side of the face. The chemical peeling sessions were done every 3 weeks until the desired response was achieved. Follow-up was carried out for 6 months after the last session. RESULTS Six patients were defaulted from the study after the first session for unknown reasons. Twenty-four patients completed the study. Twenty (83.33%) were women and four were men (16.67%). Wood's light examination showed increased contrast in all patients of mostly epidermal melasma. The number of sessions ranged from 2 to 5. All patients showed marked improvement as calculated by MASI score before and after treatment, and the response was highly statistically significant. No side effect was recorded in all treated patients. CONCLUSION Lactic acid was found to be an effective and safe peeling agent in the treatment of melasma, and it was as effective as Jessner's solution. [source] Fractional CO2 laser: a novel therapeutic device upon photobiomodulation of tissue remodeling and cytokine pathway of tissue repairDERMATOLOGIC THERAPY, Issue 2009F. Prignano ABSTRACT Minimally ablative fractional laser devices have gained acceptance as a preferred method for skin resurfacing. Notable improvements in facial rhytides, photodamage, acne scarring, and skin laxity have been reported. The aim of the present work was to compare how different CO2 laser fluences, by modulating the secretory pathway of cytokines, are able to influence the wound-healing process, and how these fluences are associated with different clinical results. Eighteen patients, all with photodamaged skin, were treated using a fractional CO2 laser (SmartXide DOT, Deka M.E.L.A., Florence, Italy) with varying laser fluences (2.07, 2.77, and 4.15 J/cm2). An immunocytochemical study was performed at defined end points in order to obtain information about specific cytokines of the microenvironment before and after treatment. The secretory pathway of cytokines changed depending on the re-epithelization and the different laser fluences. Different but significant improvements in wrinkles, skin texture, and hyperpigmentation were definitely obtained when using 2.07, 2.77, and 4.15 J/cm2, indicating fractional CO2 laser as a valuable tool in photorejuvenation with good clinical results, rapid downtime, and an excellent safety profile. [source] Novel functions of ribosomal protein S6 in growth and differentiation of Dictyostelium cellsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 6 2009Kazutaka Ishii We have previously shown that in Dictyostelium cells a 32 kDa protein is rapidly and completely dephosphorylated in response to starvation that is essential for the initiation of differentiation (Akiyama & Maeda 1992). In the present work, this phosphoprotein was identified as a homologue (Dd-RPS6) of ribosomal protein S6 (RPS6) that is an essential member for protein synthesis. As expected, Dd-RPS6 seems to be absolutely required for cell survival, because we failed to obtain antisense-RNA mediated cells as well as Dd-rps6 -null cells by homologous recombination in spite of many trials. In many kinds of cell lines, RPS6 is known to be located in the nucleus and cytosol, but Dd-RPS6 is predominantly located in the cell cortex with cytoskeletons, and in the contractile ring of just-dividing cells. In this connection, the overexpression of Dd-RPS6 greatly impairs cytokinesis during axenic shake-cultures in growth medium, resulting in the formation of multinucleate cells. Much severe impairment of cytokinesis was observed when Dd-RPS6-overexpressing cells (Dd-RPS6OE cells) were incubated on a living Escherichia coli lawn. The initiation of differentiation triggered by starvation was also delayed in Dd-RPS6OE cells. In addition, Dd-RPS6OE cells exhibit defective differentiation into prespore cells and spores during late development. Thus, it is likely that the proper expression of Dd-RPS6 may be of importance for the normal progression of late differentiation as well as for the initiation of differentiation. [source] Expression, functional, and structural analysis of proteins critical for otoconia developmentDEVELOPMENTAL DYNAMICS, Issue 10 2010Yinfang Xu Abstract Otoconia, developed during late gestation and perinatal stages, couple mechanic force to the sensory hair cells in the vestibule for motion detection and bodily balance. In the present work, we have investigated whether compensatory deposition of another protein(s) may have taken place to partially alleviate the detrimental effects of Oc90 deletion by analyzing a comprehensive list of plausible candidates, and have found a drastic increase in the deposition of Sparc-like 1 (aka Sc1 or hevin) in Oc90 null versus wt otoconia. We show that such up-regulation is specific to Sc1, and that stable transfection of Oc90 and Sc1 full-length expression constructs in NIH/3T3 cells indeed promotes matrix calcification. Analysis and modeling of Oc90 and Sc1 protein structures show common features that may be critical requirements for the otoconial matrix backbone protein. Such information will serve as the foundation for future regenerative purposes. Developmental Dynamics 239:2659,2673, 2010. © 2010 Wiley-Liss, Inc. [source] Zac1 is expressed in progenitor/stem cells of the neuroectoderm and mesoderm during embryogenesis: Differential phenotype of the Zac1-expressing cells during developmentDEVELOPMENTAL DYNAMICS, Issue 2 2005Tony Valente Abstract Zac1, a new zinc-finger protein that regulates both apoptosis and cell cycle arrest, is abundantly expressed in many neuroepithelia during early brain development. In the present work, we study the expression of Zac1 during early embryogenesis and we determine the cellular phenotype of the Zac1-expressing cells throughout development. Our results show that Zac1 is expressed in the progenitor/stem cells of several tissues (nervous system, skeleton, and skeletal muscle), because they colocalize with several progenitor/stem markers (Nestin, glial fibrillary acidic protein, FORSE-1, proliferating cell nuclear antigen, and bromodeoxyuridine). In postnatal development, Zac1 is expressed in all phases of the life cycle of the chondrocytes (from proliferation to apoptosis), in some limbic ,-aminobutyric acid-ergic neuronal subpopulations, and during developmental myofibers. Therefore, the intense expression of Zac1 in the progenitor/stem cells of different cellular lineages during the proliferative cycle, before differentiation into postmitotic cells, suggests that Zac1 plays an important role in the control of cell fate during neurogenesis, chondrogenesis, and myogenesis. Developmental Dynamics 233:667,679, 2005. © 2005 Wiley-Liss, Inc. [source] G,, that interacts with adenylyl cyclase in opioid tolerance originates from a Gs proteinDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2006Hoau-Yan Wang Abstract We previously demonstrated that chronic morphine induces a change in G protein coupling by the mu opioid receptor (MOR) from Gi/o to Gs, concurrent with the instatement of an interaction between G,, and adenylyl cyclase types II and IV. These two signaling changes confer excitatory effects on the cell in place of the typical inhibition by opioids and are associated with morphine tolerance and dependence. Both signaling changes and these behavioral manifestations of chronic morphine are attenuated by cotreatment with ultra-low-dose naloxone. In the present work, using striatum from chronic morphine-treated rats, we isotyped the G, within Gs and Go heterotrimers that coupled to MOR and compared these to the G, isotype of the G,, that interacted with adenylyl cyclase II or IV after chronic morphine treatment. Isotyping results show that chronic morphine causes a Gs heterotrimer associated with MOR to release its G,, to interact with adenylyl cyclase. These data suggest that the switch to Gs coupling by MOR in response to chronic morphine, which is attenuated by ultra-low-dose opioid antagonist cotreatment, leads to a two-pronged stimulation of adenylyl cyclase utilizing both G, and G,, subunits of the Gs protein novel to this receptor. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Hemispheric asymmetries in children's perception of nonlinguistic human affective soundsDEVELOPMENTAL SCIENCE, Issue 1 2004Seth D. Pollak In the present work, we developed a database of nonlinguistic sounds that mirror prosodic characteristics typical of language and thus carry affective information, but do not convey linguistic information. In a dichotic-listening task, we used these novel stimuli as a means of disambiguating the relative contributions of linguistic and affective processing across the hemispheres. This method was applied to both children and adults with the goal of investigating the role of developing cognitive resource capacity on affective processing. Results suggest that children's limited computational resources influence how they process affective information and rule out attentional biases as a factor in children's perceptual asymmetries for nonlinguistic affective sounds. These data further suggest that investigation of perception of nonlinguistic affective sounds is a valuable tool in assessing interhemispheric asymmetries in affective processing, especially in parceling out linguistic contributions to hemispheric differences. [source] Glycemic risk factors of diabetic vascular complications: the role of glycemic variabilityDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 3 2009Francesco Zaccardi Abstract Achieving adequate targets relatively to all risk factors is considered a standard of care for patients with diabetes mellitus. To date, current guidelines underline the importance of the ,glucose triad' (post-prandial glucose, fasting plasma glucose and glycated haemoglobin) as the three glycemic factors that should be controlled in diabetes care; however, several literature data show that optimizing glycemic control needs achieving a control of glycemic variations. The objective of the present work is reviewing biological and clinical data supporting the role of glycemic variability, its measurement and relationship with the three other well-known glycemic risk factors and evidencing the areas that need further investigation. At last, we propose a simple model that summarizes the ,glucose triad' plus the ,new' risk factor glycemic variability (the ,Pyramid of the Risk'). Copyright © 2009 John Wiley & Sons, Ltd. [source] Gestational diabetes affects platelet behaviour through modified oxidative radical metabolismDIABETIC MEDICINE, Issue 1 2004L. Mazzanti Abstract Aims Patients with Type 1 and Type 2 diabetes mellitus show altered platelet function including decreased nitric oxide synthase (NOS) activity and increased peroxynitrite production. Gestational diabetes mellitus (GDM) is a clinical condition which is ideal for evaluating short-term effects of impaired glucose metabolism, ruling out the possibility that the platelet abnormalities are a consequence of diabetic complications. The aim of the present work was to study NO metabolism in platelets from pregnant women with GDM. The production of peroxides was also studied as it is strongly involved in peroxynitrite formation. Methods Platelet NOS activity and peroxynitrite production, levels of hydroperoxides and thiobarbituric acid reactive substances (TBARS) in platelet membranes in the basal state and after in vitro peroxidative stress with phenylhydrazine were determined in 40 pregnant women with GDM, 40 healthy pregnant women (pregnant controls) of comparable age and gestational age, and 15 healthy non-pregnant women (controls). Results NOS activity was significantly increased in both groups of pregnant women compared with non-pregnant ones, and in GDM women compared with pregnant controls. Production of peroxynitrite was higher in GDM women than in pregnant controls, who also had significantly reduced production compared with non-pregnant women. Basal levels of peroxidation of the platelet membranes evaluated either by hydroperoxide content and TBARS levels or the susceptibility to peroxidation were increased in GDM patients in comparison with both control groups. Conclusions We have shown a modification in platelet NO and peroxynitrite production and an increase in platelet indicators of oxidative stress in GDM women compared with healthy pregnant women which might be at the basis of a cellular dysfunction. [source] Early survival of marble trout Salmo marmoratus: evidence for density dependence?ECOLOGY OF FRESHWATER FISH, Issue 2 2007S. Vincenzi Abstract,,, The role of endogenous and exogenous factors in regulating population dynamics of freshwater salmonids is still a matter of debate. The aim of the present work was to assess the relative importance of density-dependent and -independent factors in determining the survival of marble trout (Salmo marmoratus) yearlings in two populations living in Slovenian streams (Zakojska and Gorska). The investigation was performed by combining a classical life table analysis with Monte Carlo simulation. Size-dependent fecundity was estimated by stripping wild adults in the fish farm. A significant positive relationship was found between length of marble trout females and the number of eggs produced. Egg density was the major determinant of survival from eggs to age 1+ (,0) in both streams. Residuals of the relationship between ,0 and egg density were positively correlated with rainfall only in Zakojska, probably because, within a certain range, more intense rainfalls increases stream flow and, consequently, suitable habitat for trout. Our study shows how density-dependent and environmental factors can interact to determine the survival of marble trout during the first year of life. [source] Anticipating Regret: Why Fewer Options May Be BetterECONOMETRICA, Issue 2 2008Todd Sarver We study preferences over menus which can be represented as if the agent selects an alternative from a menu and experiences regret if her choice is ex post inferior. Since regret arises from comparisons between the alternative selected and the other available alternatives, our axioms reflect the agent's desire to limit her options. We prove that our representation is essentially unique. We also introduce two measures of comparative regret attitudes and relate them to our representation. Finally, we explore the formal connection between the present work and the literature on temptation. [source] Capillary electrophoresis-electrospray-mass spectrometry in peptide analysis and peptidomicsELECTROPHORESIS, Issue 10 2008Miguel Herrero Abstract In the present work, an exhaustive review of the main developments and applications of CE-MS for peptide analysis is given. This review includes the use of different CE separation modes, MS analyzers, capillary coatings, preconcentration techniques, on-chip applications as well as other different multidimensional strategies for peptide analysis. Key applications are critically discussed and relevant works published from January 2000 to May 2007 are summarized including information concerning the type of sample, CE-MS parameters as well as some figures of merit of the different CE-MS procedures developed for peptide analysis and peptidomics. [source] Structure,activity relationships for the mutagenicity and carcinogenicity of simple and ,-, unsaturated aldehydesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2003Romualdo Benigni Abstract Aldehydes are important industrial compounds that are used for the synthesis of chemicals and pharmaceuticals and as solvents, food additives, and disinfectants. Because of their reactivity, aldehydes are able to interact with electron-rich biological macromolecules and adverse health effects have been reported, including general toxicity, allergenic reactions, mutagenicity, and carcinogenicity. The cost, time, and number of animals necessary to adequately screen these chemicals places serious limitations on the number of aldehydes whose health potential can be studied and points to the need of using alternative methods for assessing, at least in a preliminary way, the risks associated with the use of aldehydes. A method of choice is the study of quantitative structure,activity relationships (QSARs). In the present work, we present QSAR models for the mutagenicity and carcinogenicity of simple aldehydes and ,-, unsaturated aldehydes. The models point to the role of electrophilicity, bulkiness, and hydrophobicity in the genotoxic activity of the aldehydes and lend themselves to the prediction of the activity of other untested chemicals of the same class. Environ. Mol. Mutagen. 42:136,143, 2003. © 2003 Wiley-Liss, Inc. [source] Application of supercritical fluid extraction to regenerate spent Pd-active carbon catalystENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2007Lidia D Abstract Pd-active carbon-type catalysts are used in a wide variety of processes, typical examples of which are liquid-phase hydrogenation reactions. In the case of these catalysts, a loss of their catalytic activity is observed. The aim of the present work was to assess the possibility of regenerating spent Pd/AC catalysts using supercritical fluid extraction. The following Pd/AC catalyst samples were investigated and compared: a commercial 10 wt % Pd catalyst (Aldrich) (denoted by CC), a spent catalyst (SC), SC subjected to supercritical fluid,CO2 extraction (SC/SFE/C), SC subjected to supercritical fluid,CO2,ethanol extraction (SC/SFE/C-Et), and SC subjected to supercritical fluid,ethane,propane extraction (SC/SFE/E-P). The last three catalysts were additionally subjected to heating in a hydrogen atmosphere at 410 K for 3 h. These were denoted by SC/SFE/C/H, SC/SFE/C-Et/H, and SC/SFE/E-P/H, respectively. The spent Pd/AC catalyst (SC) consists of mixed CC samples used in the reduction with hydrogen of various organic compounds. The catalysts CC, SC/SFE/C, SC/SFE/C/H, SC/SFE/C-Et/H, and SC/SFE/E-P/H were tested in the reduction of octanoylbenzene with hydrogen. The activity of the catalysts was estimated by measuring the reaction time and also the amount of hydrogen used in relation to the theoretical quantity required for the reaction. XPS and XRD methods were used to evaluate the changes occurring in the form of the palladium present on the Pd/AC catalyst surface during the regeneration processes. It was found that supercritical fluid-CO2 extraction followed by heating in a hydrogen atmosphere is the most effective method for regenerating that catalyst. The results of our investigations indicate that regeneration of a spent Pd/AC catalyst, irrespective of the reaction in which it has been used, should be based on the complete removal of byproducts, the purification of the catalyst surface, and the restoration of the original form of the palladium. The procedure proposed in this paper, i.e. SFE (CO2) and heating in H2, fulfils both the conditions mentioned above. © 2007 American Institute of Chemical Engineers Environ Prog, 2007 [source] Arsenate toxicity for wheat and lettuce in six Chinese soils with different propertiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Qing Cao Abstract To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination. [source] Uptake and accumulation of sediment-associated 4-nonylphenol in a benthic invertebrate (Lumbriculus variegatus, freshwater oligochaete)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2005Valeria Croce Abstract In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 × 10,2 (± 0.2 × 10,2; [g carbon/(g lipid-h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 ± 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators. [source] Degradation of nonylphenol ethoxylates in estuarine sediment under aerobic and anaerobic conditionsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2003P. Lee Ferguson Abstract Nonylphenol ethoxylate (NPEO) surfactants and their metabolites are ubiquitous contaminants of the aquatic environment. Despite considerable interest in the environmental fate of these compounds due to concerns over toxicity and estrogenic activity, the pathways of NPEO degradation in sediments have not previously been reported, in spite of the fact that sediment appears to be an important sink for these compounds in the environment. In the present work, we have examined the rates and pathways of NPEO degradation in batch sediment slurry experiments using radiolabeled NPEO mixtures. Results suggest that NPEOs are more persistent in sediments under anaerobic conditions than in the presence of oxygen. In addition, it was illustrated that NPEO degradation proceeds via separate pathways in oxic and anoxic sediment. Discernible metabolites were identified and an overall mass balance for NPEO degradation in oxic and anoxic sediment was achieved. In contrast with previous studies, no evidence was observed for net production of nonylphenol from NPEOs during aerobic or anaerobic degradation. The observed relative rates at which NPEO ethoxymers disappeared in the sediment slurry experiments were consistent with previous reports for these compounds in sediment and other environmental media, although the absolute rates measured were somewhat faster than those reported for field sediments. [source] Modeling pentachlorophenol bioavailability and bioaccumulation by the freshwater fingernail clam Sphaerium corneum using artificial particles and humic acidsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Noemi R. Verrengia Guerrero Abstract The uptake of anthropogenic chemicals by benthic bivalves may occur through the water phase and also by the ingestion of particles from both the suspended matter and bottom sediments. Many chemicals sorb to sediments and, subsequently, are released in the digestive tract of animals. The assessment of sediment-bound chemicals has been difficult because of the complexity of the association between these chemicals and natural particles. To simplify this complexity, we previously devised a test system using artificial particles with known chemical structures. In the present work, we improved this experimental design by adding humic materials as a source of organic matter. Bioassays were conducted by exposing the fingernail clam Sphaerium corneum to sublethal levels of pentachlorophenol (PCP) in the presence or absence of the artificial particles, treated with or without a commercial preparation of humic acids. The results showed that the bioavailability and bioaccumulation could be explained on the basis of the interactions of PCP with the active groups and/or the backbone of the resins, both in systems with or without humic acids. This model may constitute a useful approach to modeling and predicting the uptake and accumulation of chemicals bound to natural sediments. [source] Prevention of life-threatening infections due to encapsulated bacteria in children with hyposplenia or asplenia: a brief review of current recommendations for practical purposesEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2003Elio Castagnola Abstract: The aim of the present work was to summarise in a single paper all the options for prevention of life-threatening infections due to encapsulated bacteria in patients with hyposplenism or asplenia. Prevention of these infections should be obtained in all patients with 1) patient and family education, 2) prophylaxis by means of vaccination against Haemophilus influenzae and Streptococcus pneumoniae, 3) antibiotic prophylaxis, based primarily on penicillin, 4) delay of elective splenectomy or use methods of tissue salvage in splenic trauma. Vaccination is not effective against all serotypes of S. pneumoniae and Neisseria meningitidis causing life-threatening infections in hypo/asplenic patients. Moreover, antibacterial prophylaxis could select antibacterial-resistant pathogens and is highly conditioned by patient's compliance. Therefore, empirical antibacterial therapy of fever and/or suspected infection should be recommended to all splenectomised patients independently from time elapsing from splenectomy, vaccinal status and assumption of antibacterial prophylaxis. [source] Erythrocytes as targets for gamma-glutamyltranspeptidase initiated pro-oxidant reactionEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2002Hayet Aberkane Abstract: Gamma-glutamyltranspeptidase (GGT) is a well known cell plasma membrane and serum circulating enzyme. In clinical chemistry, GGT is used as a marker of alcohol consumption and drug uptake. Serum GGT activity varies in hepatobiliary diseases and cancer. This enzyme is involved in glutathione (GSH) metabolism, which is generally associated with antioxidant properties. However, in recent years, findings from our group and from others showed that GGT-catalysed extracellular metabolism of GSH leads, in the presence of iron, to the generation of reactive oxygen species (ROS). It was demonstrated that those highly reactive species oxidise lipids, cell surface protein thiols or activate transcriptional factors such as Nuclear Factor ,B (NF,B). The objective of the present work is to determine whether the red blood cells are targets for plasma GGT-initiated pro-oxidant reaction. The results obtained demonstrate that the GGT/GSH/iron system oxidises isolated erythrocyte membranes. A significant release of haemoglobin and a decrease of erythrocyte deformability are also observed. In addition, in vivo studies showed a relationship between plasma GGT activity and erythrocyte deformability in 20 studied subjects. In conclusion, GGT-mediated ROS production is able to oxidise erythrocytes and thus disturbs their functions. [source] | ||||||||||||||||||||||||||||||||||||||||||||||