-
[show abstract]
[hide abstract]
ABSTRACT: We perform a global fit study on the new agegraphic dark energy (NADE) model
in a non-flat universe by using the MCMC method with the full CMB power spectra
data from the WMAP 7-yr observations, the SNIa data from Union2.1 sample, BAO
data from SDSS DR7 and WiggleZ Dark Energy Survey, and the latest measurements
of $H_0$ from HST. We find that the value of $\Omega_{k0}$ is greater than 0 at
least at the 3$\sigma$ confidence levels (CLs), which implies that the NADE
model distinctly favors an open universe. Besides, our results show that the
value of the key parameter of NADE model,
$n=2.673^{+0.053+0.127+0.199}_{-0.077-0.151-0.222}$, at the 1--3$\sigma$ CLs,
where its best-fit value is significantly smaller than those obtained in
previous works. We find that the reason leading to such a change comes from the
different SNIa samples used. Our further test indicates that there is a
distinct tension between the Union2 sample of SNIa and other observations, and
the tension will be relieved once the Union2 sample is replaced by the Union2.1
sample. So, the new constraint result of the NADE model obtained in this work
is more reasonable than before.
12/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: The initial condition $\Omega_{\rm de}(z_{\rm ini})=n^2(1+z_{\rm
ini})^{-2}/4$ at $z_{\rm ini}=2000$ widely used to solve the differential
equation of the density of the new agegraphic dark energy (NADE) $\Omega_{\rm
de}$, makes the NADE model be a single-parameter dark-energy cosmological
model. However, we find that this initial condition is only applicable in a
flat universe with only dark energy and pressureless matter. In fact, in order
to obtain more information from current observational data, such as cosmic
microwave background (CMB) and baryon acoustic oscillations (BAO), we need to
consider the contribution of radiation. For this situation, the initial
condition mentioned above becomes invalid. To overcome this shortage, we
investigate the evolution of dark energy in the matter-dominated and
radiation-dominated epochs, and obtain a new initial condition $\Omega_{\rm
de}(z_{\rm ini})=\frac{n^2(1+z_{\rm ini})^{-2}}{4}(1+\sqrt{F(z_{\rm ini})})^2$
at $z_{\rm ini}=2000$, where
$F(z)\equiv\frac{\Omega_{r0}(1+z)}{\Omega_{m0}+\Omega_{r0}(1+z)}$ with
$\Omega_{r0}$ and $\Omega_{m0}$ being the current density parameters of
radiation and pressureless matter, respectively. This revised initial condition
is applicable for the differential equation of $\Omega_{\rm de}$ obtained in
the standard Friedmann-Robertson-Walker (FRW) universe with dark energy,
pressureless matter, radiation, and even spatial curvature, and can still keep
the NADE model being a single-parameter model. With the revised initial
condition and the observational data of type Ia supernova (SNIa), CMB and BAO,
we finally constrain the NADE model. The results show that the single free
parameter $n$ of the NADE model can be constrained tightly.
01/2012;
-
Arthritis & Rheumatism 02/2011; 63(2):568-9. · 7.87 Impact Factor
-
Arthritis & Rheumatism 11/2010; · 7.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Osteopontin (OPN) that is aberrantly produced in rheumatoid synovium is thought to play an important role in rheumatoid arthritis (RA). This study was undertaken to investigate the role of OPN in the differentiation and accumulation of Th17 cells in rheumatoid synovium.
Peripheral blood mononuclear cells and purified CD4+ T cells derived from patients with RA or healthy controls were used to test the effect of OPN in vitro. Cytokine expression was determined by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Intracellular staining and flow cytometry were used to detect the percentages of Th17 cells and OPN receptors. Signaling and molecular events were analyzed by immunoblotting and chromatin immunoprecipitation.
The levels of OPN correlated significantly with interleukin-17 (IL-17) production and the frequency of Th17 cells in the synovial fluid (SF) of RA patients. Endogenous OPN produced in RA SF was responsible for markedly increased production of IL-17 in T cells, which was blocked by OPN antibody. The effect of OPN in Th17 differentiation was mediated through a mechanism independent of the IL-6/STAT-3 pathway or other cytokines and specifically involved the OPN receptors CD44 and CD29 and the transcription factor retinoic acid-related orphan receptor (ROR). Furthermore, OPN was found to induce H3 acetylation of the IL17A gene promoter, mainly through the CD44 binding domain in CD4+ T cells, allowing the interaction of the IL17A gene locus with ROR.
This study reveals new evidence of the critical role of OPN in Th17 differentiation in rheumatoid synovitis.
Arthritis & Rheumatism 10/2010; 62(10):2900-8. · 7.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: IL-21 is a type I cytokine that like IL-2, IL-4, IL-7, IL-9, and IL-15 uses the common gamma chain of cytokine receptor. IL-21 has been shown to regulate the function of T cells, B cells, natural killer cells, and dendritic cells in immune responses. Although activated CD4(+) T cells produce IL-21, recent data suggest that novel subsets of effector T cells are the major producers in immune responses. In this study, we show that IL-21 expression correlates with the presence of Th17 cells in synovial fluid (SF) and peripheral blood in rheumatoid arthritis patients. Human CCR6+ CD4(+) T cells produce high levels of both IL-21 and IL-17. Similar to mouse T cells, IL-21 auto-regulates its own production in human CD4(+) T cells. IL-21 potently enhances Th17 proliferation and suppresses Foxp3 expression, leading to the expression of RORC. IL-21 is therefore an autocrine cytokine that regulates human Th17 cells in rheumatoid arthritis, and serves as a good target for treating this autoimmune disease.
Human immunology 04/2010; 71(4):334-41. · 2.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: IFN-beta currently serves as one of the major treatments for MS. Its anti-inflammatory mechanism has been reported as involving a shift in cytokine balance from Th1 to Th2 in the T-cell response against elements of the myelin sheath. In addition to the Th1 and Th2 groups, two other important pro-inflammatory cytokines, IL-17 and osteopontin (OPN), are believed to play important roles in CNS inflammation in the pathogenesis of MS. In this study, we examined the potential effects of IFN-beta on the regulation of OPN and IL-17 in MS patients. We found that IFN-beta used in vitro at 0.5-3 ng/mL significantly inhibited the production of OPN in primary T cells derived from PBMC. The inhibition of OPN was determined to occur at the CD4(+) T-cell level. In addition, IFN-beta inhibited the production of IL-17 and IL-21 in CD4(+) T cells. It has been described that IFN-beta suppresses IL-17 production through the inhibition of a monocytic cytokine, the intracellular translational isoform of OPN. Our further investigation demonstrated that IFN-beta also acted directly on the CD4(+) T cells to regulate OPN and IL-17 expression through the type I IFN receptor-mediated activation of STAT1 and suppression of STAT3 activity. Administration of IFN-beta to EAE mice ameliorated the disease severity. Furthermore, spinal cord infiltration of OPN(+) and IL-17(+) cells decreased in IFN-beta-treated EAE mice along with decreases in serum levels of OPN and IL-21. Importantly, decreased OPN production by IFN-beta treatment contributes to the reduced migratory activity of T cells. Taken together, the results from both in vitro and in vivo experiments indicate that IFN-beta treatment can down-regulate the OPN and IL-17 production in MS. This study provides new insights into the mechanism of action of IFN-beta in the treatment of MS.
European Journal of Immunology 09/2009; 39(9):2525-36. · 5.10 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: IFN-β currently serves as one of the major treatments for MS. Its anti-inflammatory mechanism has been reported as involving a shift in cytokine balance from Th1 to Th2 in the T-cell response against elements of the myelin sheath. In addition to the Th1 and Th2 groups, two other important pro-inflammatory cytokines, IL-17 and osteopontin (OPN), are believed to play important roles in CNS inflammation in the pathogenesis of MS. In this study, we examined the potential effects of IFN-β on the regulation of OPN and IL-17 in MS patients. We found that IFN-β used in vitro at 0.5–3 ng/mL significantly inhibited the production of OPN in primary T cells derived from PBMC. The inhibition of OPN was determined to occur at the CD4+ T-cell level. In addition, IFN-β inhibited the production of IL-17 and IL-21 in CD4+ T cells. It has been described that IFN-β suppresses IL-17 production through the inhibition of a monocytic cytokine, the intracellular translational isoform of OPN. Our further investigation demonstrated that IFN-β also acted directly on the CD4+ T cells to regulate OPN and IL-17 expression through the type I IFN receptor-mediated activation of STAT1 and suppression of STAT3 activity. Administration of IFN-β to EAE mice ameliorated the disease severity. Furthermore, spinal cord infiltration of OPN+ and IL-17+ cells decreased in IFN-β-treated EAE mice along with decreases in serum levels of OPN and IL-21. Importantly, decreased OPN production by IFN-β treatment contributes to the reduced migratory activity of T cells. Taken together, the results from both in vitro and in vivo experiments indicate that IFN-β treatment can down-regulate the OPN and IL-17 production in MS. This study provides new insights into the mechanism of action of IFN-β in the treatment of MS.
European Journal of Immunology 08/2009; 39(9):2525 - 2536. · 5.10 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Luminescent phenomenon, especially electroluminescence (EL), is studied for two samples with a structure of Si/SiO2/Si prepared by oxygen implantation. The asymmetry of EL found in this structure is attributed to the electrical asymmetry of these samples. Several luminescent spots can be observed at the exact same positions under both positive and negative bias, and their area density is about 102/cm2 in these samples. Photoemission microscope (PEM) and optical beam induced resistance change (OBIRCH) are used for the study of EL phenomenon before and after electrical breakdown of the samples, while transmission electron microscope (TEM) is used for the study of the sample's structure. Nc-Si (nanocrystal silicon) related peaks cannot be found in photoluminescence (PL) spectra for the sample containing Si islands, while oxygen defect related peaks between 350–650 nm can be found for all samples. Luminescence mechanism is discussed based on the model of defect luminescent center (DLC). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Physica Status Solidi (A) Applications and Materials 09/2007; 204(12):4272 - 4280. · 1.46 Impact Factor
-
Journal of The Electrochemical Society. 158(8):A924-A929.
