19,545 research outputs found

    Regional Differences in Heat Shock Protein 25 Expression in Brain and Spinal Cord Astrocytes of Wild-Type and SOD1 (G93A) Mice

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    Heterogeneity of glia in different CNS regions may contribute to the selective vulnerability of neuronal populations in neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS). Here, we explored regional variations in the expression of heat shock protein 25 in glia under conditions of acute and chronic stress. Hsp27 (Hsp27; murine orthologue: Hsp25) fulfils a number of cytoprotective functions and may therefore be a possible therapeutic target in ALS. We identified a subpopulation of astrocytes in primary murine mixed glial cultures that expressed Hsp25. Under basal conditions, the proportion of Hsp25-positive astrocytes was twice as high in spinal cord cultures than in cortical cultures. To explore the physiological role of the elevated Hsp25 expression in spinal cord astrocytes, we exposed cortical and spinal cord glia to acute stress, using heat stress and pro-inflammatory stimuli. Surprisingly, we observed no stress-induced increase in Hsp25 expression in either cortical or spinal cord astrocytes. Similarly, exposure to endogenous stress, as modelled in glial cultures from SOD1 G93A-ALS mice, did not increase Hsp25 expression above that observed in astrocytes from wild-type mice. In vivo, Hsp25 expression was greater under conditions of chronic stress present in the spinal cord of SOD1 G93A mice than in wild-type mice, although this increase in expression is likely to be due to the extensive gliosis that occurs in this model. Together, these results show that there are differences in the expression of Hsp25 in astrocytes in different regions of the central nervous system, but Hsp25 expression is not upregulated under acute or chronic stress conditions

    Structural and ethnobotanical characterization of velvet tamarind (Dialium guineense willd), a multipurpose tree species

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    The velvet tamarind (Dialium guineense Willd) is one of the key species for domestication in Sub-Saharan Africa. In order to help the sustainable management and conservation of this species, its structural characteristics and ethnobotanical traits were studied in the 4 vegetation types (typical dense forest, degraded dense forest, young fallow and old fallow) of the Lama forest reserve. A forest inventory was carried out in 100 randomly selected squared plots of one ha each in the 4 vegetation types. One rectangular plot of 0.15 ha was set up within each 1 ha plot for their  structural description. Moreover, 10 squared plots of 10 m side were  established on one of the diagonal in each one ha plot in order to  estimate regeneration density. An ethnobotanical survey was also carried out among 100 randomly selected people of the Holli, Fon and Adja sociocultural groups living adjacent to the forest. Results showed that there were significant differences between the 4 vegetation types according dendrometric parameters. Stem diameter structure showed a nonnormal shape. Ethnobotanical survey revealed that D. guineense is an agroforestry species and most of ethnobotanical knowledge is held by men of Holli sociocultural group.Key-words: Benin, Dialium guineense, structure, ethnobotany, Lama forest reserve, vegetation types

    Uncertainty Principle Enhanced Pairing Correlations in Projected Fermi Systems Near Half Filling

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    We point out the curious phenomenon of order by projection in a class of lattice Fermi systems near half filling. Enhanced pairing correlations of extended s-wave Cooper pairs result from the process of projecting out s-wave Cooper pairs, with negligible effect on the ground state energy. The Hubbard model is a particularly nice example of the above phenomenon, which is revealed with the use of rigorous inequalities including the Uncertainty Principle Inequality. In addition, we present numerical evidence that at half filling, a related but simplified model shows ODLRO of extended s-wave Cooper pairs.Comment: RevTex 11 pages + 1 ps figure. Date 19 September 1996, Ver.

    Physicians’ views of performance reports: grading the graders

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    Structural and ethnobotanical characterization of velvet tamarind (Dialium guineense willd), a multipurpose tree species

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    The velvet tamarind (Dialium guineense Willd) is one of the key species for domestication in Sub-Saharan Africa. In order to help the sustainable  management and conservation of this species, its structural characteristics and ethnobotanical traits were studied in the 4 vegetation types (typical  dense forest, degraded dense forest, young fallow and old fallow) of the  Lama forest reserve. A forest inventory was carried out in 100 randomly  selected squared plots of one ha each in the 4 vegetation types. One  rectangular plot of 0.15 ha was set up within each 1 ha plot for their   structural descri ption. Moreover, 10 squared plots of 10 m side were  established on one of the diagonal in each one ha plot in order to estimate regeneration density. An ethnobotanical survey was also carried out among 100 randomly selected people of the Holli, Fon and Adja sociocultural  groups living adjacent to the forest. Results showed that there were   significant differences between the 4 vegetation types according   dendrometric parameters. Stem diameter structure showed a nonnormalshape. Ethnobotanical survey revealed that D. guineense is an agroforestry species and most of ethnobotanical knowledge is held by men of Holli sociocultural group.Key-words: Benin, Dialium guineense, structure, ethnobotany, Lama forest reserve, vegetation types

    The chemopreventive polyphenol Curcumin prevents hematogenous breast cancer metastases in immunodeficient mice

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    Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitro and in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA- MB- 231 cells in correlation with reduced activation of the survival pathway NF kappa B, as a consequence of diminished I kappa B and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NF kappa B activity and transcriptional downregulation of AP-1. NF kappa B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NF kappa B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NF kappa B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible. Copyright (c) 2007 S. Karger AG, Basel

    Understanding the edge effect in TASEP with mean-field theoretic approaches

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    We study a totally asymmetric simple exclusion process (TASEP) with one defect site, hopping rate q<1q<1, near the system boundary. Regarding our system as a pair of uniform TASEP's coupled through the defect, we study various methods to match a \emph{finite} TASEP and an \emph{infinite} one across a common boundary. Several approximation schemes are investigated. Utilizing the finite segment mean-field (FSMF) method, we set up a framework for computing the steady state current JJ as a function of the entry rate % \alpha and qq. For the case where the defect is located at the entry site, we obtain an analytical expression for J(α,q)J(\alpha, q) which is in good agreement with Monte Carlo simulation results. When the defect is located deeper in the bulk, we refined the scheme of MacDonald, et.al. [Biopolymers, \textbf{6}, 1 (1968)] and find reasonably good fits to the density profiles before the defect site. We discuss the strengths and limitations of each method, as well as possible avenues for further studies.Comment: 16 pages, 4 figure

    Fate and transport of volatile organic compounds in glacial till and groundwater at an industrial site in Northern Ireland

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    Volatile organic compound (VOC) contamination of subsurface geological material and groundwater was discovered on the Nortel Monkstown industrial site, Belfast, Northern Ireland. The objectives of this study were to (1) investigate the characteristics of the geological material and its influences on contaminated groundwater flow across the site using borehole logs and hydrological evaluations, and (2) identify the contaminants and examine their distribution in the subsurface geological material and groundwater using chemical analysis. This report focuses on the eastern car park (ECP) which was a former storage area associated with trichloroethene (TCE) degreasing operations. This is where the greatest amount of volatile organic compounds (VOCs), particularly TCE, were detected. The study site is on a complex deposit of clayey glacial till with discontinuous coarser grained lenses, mainly silts, sands and gravel, which occur at 0.45-7.82 m below ground level (bgl). The lenses overall form an elongated formation that acts as a small unconfined shallow aquifer. There is a continuous low permeable stiff clayey till layer beneath the lenses that performs as an aquitard to the groundwater. Highest concentrations of VOCs, mainly TCE, in the geological material and groundwater are in these coarser lenses at similar to 4.5-7 m bgl. Highest TCE measurements at 390,000 mu g L-1 for groundwater and at 39,000 mu g kg(-1) at 5.7 m for geological material were in borehole GA19 in the coarse lens zone. It is assumed that TCE gained entrance to the subsurface near this borehole where the clayey till was thin to absent above coarse lenses which provided little retardation to the vertical migration of this dense non-aqueous phase liquid (DNAPL) into the groundwater. However, TCE is present in low concentrations in the geological material overlying the coarse lens zone. Additionally, VOCs appear to be associated with poorly drained layers and in peat &lt; 3.0 m bgl in the ECP. Some indication of natural attenuation as VOCs degradation products vinyl chloride (VC) and dichloromethane (DCM) also occur on the site

    Scaling and Formulary cross sections for ion-atom impact ionization

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    The values of ion-atom ionization cross sections are frequently needed for many applications that utilize the propagation of fast ions through matter. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. This paper briefly summarizes the most important theoretical results and approaches to cross section calculations in order to place the discussion in historical perspective and offer a concise introduction to the topic. Based on experimental data and theoretical predictions, a new fit for ionization cross sections is proposed. The range of validity and accuracy of several frequently used approximations (classical trajectory, the Born approximation, and so forth) are discussed using, as examples, the ionization cross sections of hydrogen and helium atoms by various fully stripped ions.Comment: 46 pages, 8 figure

    The Second Byurakan Survey Galaxies. I. The Optical Database

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    A database for the entire catalog of the Second Byurakan Survey (SBS) galaxies is presented. It contains new measurements of their optical parameters and additional information taken from the literature and other databases. The measurements were made using Ipg(near-infrared), Fpg(red) and Jpg(blue) band images from photographic sky survey plates obtained by the Palomar Schmidt telescope and extracted from the STScI Digital Sky Survey (DSS). The database provides accurate coordinates, morphological type, spectral and activity classes, apparent magnitudes and diameters, axial ratios, and position angles, as well as number counts of neighboring objects in a circle of radius 50 kpc. The total number of individual SBS objects in the database is now 1676. The 188 Markarian galaxies which were re-discovered by SBS are not included in this database. We also include redshifts that are now available for 1576 SBS objects, as well as 2MASS infrared magnitudes for 1117 SBS galaxies.Comment: 13 pages, 1 figure, 1 tabl
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