1,246 research outputs found

    Full Length Research Paper Curcumin induces cleavage of -catenin by activation of capases and downregulates the &#946-catenin/Tcf signaling pathway in HT-29 cells

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    β-Catenin/Tcf-4 signaling pathway plays important roles in colorectal tumorigenesis. RT-PCR, western blotting and immunoprecipitation were used to study the effects of curcumin on β-catenin/Tcf-4 signaling pathway in HT-29 cells. Treatment of curcumin could induce cleavage of β-catenin and the cleavage could be inhibited by caspase inhibitors. The association of β-catenin with Tcf-4 in nucleus could be inhibited by curcumin. The expression of c-myc and cyclinD1 was downregulated by curcumin, which could not be blocked by Z-DEVD-FMK. The results showed curcumin could induce thecleavage of β-catenin by activition of caspases and downregulate the activity of β-catenin/Tcf signaling pathway independent of the caspases in HT-29 cells

    Spin-polarized transport in a lateral two-dimensional diluted magnetic semiconductor electron gas

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    The transport property of a lateral two-dimensional diluted magnetic semiconductor electron gas under a spatially periodic magnetic field is investigated theoretically. We find that the electron Fermi velocity along the modulation direction is highly spin-dependent even if the spin polarization of the carrier population is negligibly small. It turns out that this spin-polarized Fermi velocity alone can lead to a strong spin polarization of the current, which is still robust against the energy broadening effect induced by the impurity scattering.Comment: 3 pages, 3 figures, submitted to Appl. Phys. Let

    Interplay between s-d exchange interaction and Rashba effect: spin-polarized transport

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    We investigate the spin-polarized transport properties of a two-dimensional electron gas in a n-type diluted magnetic narrow gap semiconductor quantum well subjected to a perpendicular magnetic and electric field. Interesting beating patterns in the magneto resistance are found which can be tuned significantly by varying the electric field. A resonant enhancement of spin-polarized current is found which is induced by the competition between the s-d exchange interaction and the Rashba effect [Y. A. Bychkov and E. I. Rashba, J. Phys. C 17, 6039 (1984)].Comment: 4 pages, 3 figures, Appl. Phys. Lett. (in press

    Phenotypic and functional modulation of porcine monocyte-derived dendritic cells for foot-and-mouth disease virus

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    Dendritic cells (DCs) play an important role in inducing primary antigen-specific immune responses to viral antigens. In this study, the peripheral blood monocyte-derived (PBMC) were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4. After 6 days of culture, immature monocyte-derived dendritic cells (Mo-DCs) were generated. The addition of lipopolysaccharide (LPS) during differentiation of Mo-DCs enhanced their ability to stimulate allogeneic mixed lymphocyte reaction (MLR) and alter their ability to produce cytokines. Then, we investigated the interaction between foot-and-mouth disease virus (FMDV) and porcine Mo-DCs in vitro and confirmed that the immunological phenotype and function of porcine Mo-DCs were modulated during FMDV infection. A down-regulated expression of MHC II and CD1 were observed at 48 h post FMDV infection. In addition, the infected porcine Mo-DCs exhibited ultrastructural morphological changes, FMDV-infected porcine Mo-DCs failed to stimulate T cell proliferation in vitro. Moreover, infection of porcine Mo-DCs in vitro induced the secretion of IFN-γ and the suppressive cytokine IL-10 in porcine Mo-DCs. Results indicated that the down-regulation of MHC II and CD1 molecules and the increased secretion of the IFN-γ and IL-10 cytokines might be the mechanisms that FMDV uses to evade the host immune responses.Key words: Dendritic cells, foot-and-mouth disease virus, MHC II, modulation, cytokines

    RXRα acts as a carrier for TR3 nuclear export in a 9-cis retinoic acid-dependent manner in gastric cancer cells

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    Retinoid X receptor (RXR) plays a crucial role in the cross talk between retinoid receptors and other hormone receptors including the orphan receptor TR3, forming different heterodimers that transduce diverse steroid/thyroid hormone signaling. Here we show that RXRalpha exhibits nucleocytoplasmic shuttling in MGC80-3 gastric cancer cells and that RXRalpha, shuttling is energy-dependent through a nuclear pore complex (NPC)mediated pathway for its import and an intact DNA binding domain-mediated pathway for its export. In the presence of its ligand 9-cis retinoic acid, RXRalpha was almost exclusively located in the cytoplasm. More importantly, we also show that RXRalpha. acts as a carrier to assist translocation of TR3, which plays an important role in apoptosis. Both RXRalpha and TR3 colocalized in the nucleus; however, upon stimulation by 9-cis retinoic acid they cotranslocated to the cytoplasm and then localized in the mitochondria. TR3 export depends on RXRalpha as in living cells GFP-TR3 alone did not result in export from the nucleus even in the presence of 9-cis retinoic acid, whereas GFP-TR3 cotransfected with RXRalpha was exported out of the nucleus in response to 9-cis retinoic acid. Moreover, specific reduction of RXRalpha levels caused by anti-sense RXRalpha abolished TR3 nuclear export. In contrast, specific knockdown of TR3 by antisense-TR3 or TR3-siRNA did not affect RXRalpha shuttling. These results indicate that RXRalpha is responsible for TR3 nucleocytoplasmic translocation, which is facilitated by the RXRalpha ligand 9-cis retinoic acid. In addition, mitochondrial TR3, but not RXRalpha was critical for apoptosis, as TR3 mutants that were distributed in the mitochondria induced apoptosis in the presence or absence of 9-cis retinoic acid. These data reveal a novel aspect of RXRalpha function, in which it acts as a carrier for nucleocytoplasmic translocation of orphan receptors

    HIV-Infected Former Plasma Donors in Rural Central China: From Infection to Survival Outcomes, 1985–2008

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    BACKGROUND: The HIV epidemic among former plasma donors (FPDs) in rural Central China in the early-mid 1990s is likely the largest known HIV-infected cohort in the world related to commercial plasma donation but has never been fully described. The objectives of this study are to estimate the timing and geographic spread of HIV infection in this cohort and to demonstrate the impact of antiretroviral therapy on survival outcomes. METHODOLOGY/PRINCIPAL FINDINGS: HIV-infected FPDs were identified using the national HIV epidemiology and treatment databases. Locations of subjects were mapped. Dates of infection and survival were estimated using the midpoint date between initial-final plasma donation dates from 1985-2008 among those with plasma donation windows ≤2 years. Among 37,084 FPDs in the two databases, 36,110 were included. 95% were located in focal areas of Henan Province and adjacent areas of surrounding provinces. Midpoint year between initial-final plasma donation dates was 1994 among FPDs with known donation dates. Median survival from infection to AIDS was 11.8 years and, among those not treated, 1.6 years from AIDS to death. Among those on treatment, 71% were still alive after five years. Using Cox proportional hazard modeling, untreated AIDS patients were 4.9 times (95% confidence interval 4.6-5.2) more likely to die than those on treatment. CONCLUSIONS/SIGNIFICANCE: The epidemic of HIV-infected FPD in China was not widespread throughout China but rather was centered in Henan Province and the adjacent areas of surrounding provinces. Even in these areas, infections were concentrated in focal locations. Overall, HIV infections in this cohort peaked in 1994, with median survival of 13.4 years from infection to death among those not treated. Among AIDS patients on treatment, 71% were still alive after five years

    A Phase Equilibrium Model for Gas Hydrates Considering Pore-Size Distribution of Sediments

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    The phase equilibrium condition for gas hydrates has been an important and difficult subject in gas hydrate-related research. In this paper, the mechanism of the effect of pore-size distribution on the phase equilibrium is first explored and the concept of effective pore radius is proposed. Using information on the pore-size distribution of sediments, a relationship between hydrate saturation and effective pore radius is developed. Combined with the van der Waals-Platteeuw model, this relationship was then used to develop a new phase equilibrium model for gas hydrates in sediments, which can properly account for the effect of pore-size distribution. In contrast to the traditional models, this new model does not represent a curve on the p-T plane but instead addresses the relationship between the temperature, pressure, and hydrate saturation. Such a feature allows the new model to take into account the effect of pore-size distribution on the phase equilibrium while treating the formation and/or dissolution processes of gas hydrates in pores more realistically. The simulated results were compared with the experimental data available in literature showing that the new model gives better results compared with the other traditional models. Given the temperature and the pore pressure, the hydrate saturation can be determined using the proposed model. Therefore, the new model can be used to estimate the amount of hydrate resources in the field
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