Generalized quantization condition in topological insulator

The topological magnetoelectric effect (TME) is the fundamental quantization effect for topological insulators in units of the fine structure constant $\alpha$. In [Phys. Rev. Lett. 105, 166803(2010)], a topological quantization condition of the TME is given under orthogonal incidence of the optical beam, in which the wave length of the light or the thickness of the TI film must be tuned to some commensurate values. This fine tuning is difficult to realize experimentally. In this article, we give manifestly $SL(2,\mathbb{Z})$ covariant expressions for Kerr and Faraday angles at oblique incidence at a topological insulator thick film. We obtain a generalized quantization condition independent of material details, and propose a more easily realizable optical experiment, in which only the incidence angle is tuned, to directly measure the topological quantization associated with the TME.Comment: 3 figure

ISG15 inhibits IFN- a -Resistant liver cancer cell growth

Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide. Interferon-a (IFN-a) has been widely used in the treatment of HCC, but patients eventually develop resistance. ISG15 ubiquitin-like modifier (ISG15) is a ubiquitin-like protein transcriptionally regulated by IFN-a which shows antivirus and antitumor activities. However, the exact role of ISG15 is unknown. In the present study, we showed that IFN-a significantly induced ISG15 expression but failed to induce HepG2 cell apoptosis, whereas transient overexpression of ISG15 dramatically increased HepG2 cell apoptosis. ISG15 overexpression increased overall protein ubiquitination, which was not observed in cells with IFN-a-induced ISG15 expression, suggesting that IFN-a treatment not only induced the expression of ISG15 but also inhibited ISG15-mediated ubiquitination. The tumor suppressor p53 and p21 proteins are the key regulators of cell survival and death in response to stress signals such as DNA damage. We showed that p53 or p21 is only up regulated in HepG2 cells ectopically expressing ISG15, but not in the presence of IFN-a-induced ISG15. Our results suggest that ISG15 overexpression could be developed into a powerful gene-therapeutic tool for treating IFN-a-resistant HCC. © 2013 Xin-xing Wan et al

Impact of the tissue factor pathway inhibitor gene on apoptosis in human vascular smooth muscle cells

Tissue factor pathway inhibitor (TFPI) plays a vitally important role in the blood coagulation pathway. Recent studies indicated that TFPI induces apoptosis in vascular smooth-muscle cells (VSMCs) in animals. The present study investigated whether the TFPI gene could also induce apoptosis in human vascular smooth-muscle cells (hVSMCs). Such cells were isolated from human umbilical arteries and subsequently transfected with pIRES-TFPI plasmid (2 μg/mL). MTT assaying and cell counting were applied to measure cell viability and proliferation, RT-PCR was utilized to analyze TFPI gene expression in the cells. Apoptosis was analyzed by fluorescence activated cell sorting (FACS). Several key proteins involved in apoptosis were examined through Western blotting. It was shown that TFPI gene transfer led to its increased cellular expression, with a subsequent reduction in hVSMC proliferation. Further investigation demonstrated that TFPI gene expression resulted in lesser amounts of procaspase-3, procaspase-8 and procascase-9, and an increased release of mitochondrial cytochrome c (cyt-c) into cytoplasm, thereby implying the involvement of both extrinsic and intrinsic pathways in TFPI gene-induced apoptosis in hVSMCs

Cosmological Constraints on the Undulant Universe

We use the redshift Hubble parameter $H(z)$ data derived from relative galaxy ages, distant type Ia supernovae (SNe Ia), the Baryonic Acoustic Oscillation (BAO) peak, and the Cosmic Microwave Background (CMB) shift parameter data, to constrain cosmological parameters in the Undulant Universe. We marginalize the likelihood functions over $h$ by integrating the probability density $P\propto e^{-\chi^2/2}$. By using the Markov Chain Monte Carlo (MCMC) technique, we obtain the best fitting results and give the confidence regions on the $b-\Omega_{\rm m0}$ plane. Then we compare their constraints. Our results show that the $H(z)$ data play a similar role with the SNe Ia data in cosmological study. By presenting the independent and joint constraints, we find that the BAO and CMB data play very important roles in breaking the degeneracy compared with the $H(z)$ and SNe Ia data alone. Combined with the BAO or CMB data, one can improve the constraints remarkably. The SNe Ia data sets constrain $\Omega_{\rm m0}$ much tighter than the $H(z)$ data sets, but the $H(z)$ data sets constrain $b$ much tighter than the SNe Ia data sets. All these results show that the Undulant Universe approaches the $\Lambda \rm$CDM model. We expect more $H(z)$ data to constrain cosmological parameters in future.Comment: 10 pages,6 figures, 2 tables, accepted for publication in Research in Astronomy and Astrophysic

Constraints on smoothness parameter and dark energy using observational H(z)H(z) data

The universe, with large-scale homogeneity, is locally inhomogeneous, clustering into stars, galaxies and larger structures. Such property is described by the smoothness parameter $\alpha$ which is defined as the proportion of matter in the form of intergalactic medium. If we take consideration of the inhomogeneities in small scale, there should be modifications of the cosmological distances compared to a homogenous model. Dyer and Roeder developed a second-order ordinary differential equation (D-R equation) that describes the angular diameter distance-redshift relation for inhomogeneous cosmological models. Furthermore, we may obtain the D-R equation for observational $H(z)$ data (OHD). The density-parameter $\Omega_{\rm M}$, the state of dark energy $\omega$, and the smoothness-parameter $\alpha$ are constrained by a set of OHD in a spatially flat $\Lambda$CDM universe as well as a spatially flat XCDM universe. By using of $\chi^2$ minimization method we get $\alpha=0.81^{+0.19}_{-0.20}$ and $\Omega_{\rm M}=0.32^{+0.12}_{-0.06}$ at $1\sigma$ confidence level. If we assume a Gaussian prior of $\Omega_{\rm M}=0.26\pm0.1$, we get $\alpha=0.93^{+0.07}_{-0.19}$ and $\Omega_{\rm M}=0.31^{+0.06}_{-0.05}$. For XCDM model, $\alpha$ is constrained to $\alpha\geq0.80$ but $\omega$ is weakly constrained around -1, where $\omega$ describes the equation of the state of the dark energy ($p_{\rm X}=\omega\rho_{\rm X}$). We conclude that OHD constrains the smoothness parameter more effectively than the data of SNe Ia and compact radio sources.Comment: 11 pages, 12 figures, accepted for publication in Research in Astronomy and Astrophysic

Diaqua­bis(2,2′-biimidazole)cobalt(II) dichloride

There are independent cations and four chloride anions in the crystal structure of the title complex, [Co(C6H6N4)2(H2O)2]Cl2. In each cation, the CoII cation is coordinated by four N atoms from two biimidazole and two O atoms of two water mol­ecules; one Co atom is at a position of site symmetry m, the other at a position of site symmetry 2/m. All Cl− ions and water mol­ecules are also located on the mirror plane. Each structural unit is connected through O—H⋯Cl and N—H⋯Cl inter­molecular hydrogen bonds, forming a three–dimensional supramolecular structure

Differential expression of the catalytic subunits for PP-1 and PP-2A and the regulatory subunits for PP–2A in mouse eye

Purpose: Reversible protein phosphorylation is a fundamental regulatory mechanism in all biologic processes. Protein serine/threonine phosphatases-1 (PP-1) and 2A (PP-2A) account for 90% of serine/threonine phosphatase activity in eukaryote cells and play distinct roles in regulating multiple cellular processes and activities. Our previous studies have established the expression patterns of the catalytic subunits for PP-1 (PP-1cs) and PP-2A (PP-2Acs) in bovine and rat lenses. In the present study, we have determined the expression patterns of PP-1cs (PP-1α and PP-1β) and PP-2Acs (PP-2Aα and PP-2Aβ) in the retina and cornea along with the ocular lens of the mouse eye. Moreover, since the function of PP-2A is largely relied on its regulatory subunits, we have also analyzed the expression patterns of the genes encoding the scaffold A subunits of PP-2A, PP2A-Aα and PP2A-Aβ, and the regulatory B family subunits of PP-2A, PP2A-Bα, PP2A-Bβ, and PP2A-Bγ. In addition, we have also demonstrated the differential protections of PP-1 and PP-2A in mouse lens epithelial cell line, αTN4-1, against oxidative stress-induced apoptosis. Methods: Total RNAs and proteins were extracted from the retina, lens epithelium, lens fiber cells, and cornea of the mouse eye. Reverse transcription polymerase chain reaction (RT-PCR) and real time PCR were used to detect the mRNA expression. Western blot and immunohistochemistry analysis were applied to examine the protein expression and distribution. Stable clones of αTN4-1 cells expressing either PP-1α or PP-2Aα were used to analyze the differential protections against oxidative stress-induced apoptosis. Results: PP-1 is more abundant than PP-2A in the mouse eye. The catalytic subunits for PP-1 and PP-2A display similar expression patterns in the retina and cornea but much reduced in the lens. The mRNAs for all five isoforms of PP2A-A and PP2A-B subunits are highly expressed in the retina, but only three out of the five mRNAs are expressed in the cornea. In the ocular lens, only PP2A-Aβ and PP2A-Bγ mRNAs are clearly detectable. The A and B subunit proteins of PP-2A are highly expressed in the retina and cornea but are much reduced in the ocular lens. PP2A-Aα/β are differentially distributed in the mouse retina. When transfected into mouse lens epithelial cells, αTN4-1, PP-1α and PP-2Aα display differential protection against oxidative stress-induced apoptosis. Conclusions: Our results lead to the following conclusions regarding PP-1 and PP-2A in mouse eye: 1) PP1 is a more abundant phosphatase than PP-2A; 2) both PP-1 and PP-2A may play important roles, and the functions of PP-2A appear to be highly regulated by various regulatory subunits; and 3) the genes encoding PP-1α/β, PP-2Aα/ β, PP-2A-Aα/β, and PP-2A-B α/β/γ are all differentially expressed

Effects of Combined Anisodamine and Neostigmine Treatment on the Inflammatory Response and Liver Regeneration of Obstructive Jaundice Rats after Hepatectomy

Background. Cholestasis is associated with high rates of morbidity and mortality in patients undergoing major liver resection. This study aimed to evaluate the effects of a combined anisodamine and neostigmine (Ani+Neo) treatment on the inflammatory response and liver regeneration in rats with obstructive jaundice (OJ) after partial hepatectomy. Materials and Methods. OJ was induced in the rats by bile duct ligation. After 7 days biliary drainage and partial hepatectomy were performed. These rats were assigned to a saline group or an Ani+Neo treatment group. The expressions of inflammatory mediators, liver regeneration, and liver damage were assessed at 48 h after hepatectomy. Results. The mRNA levels of TNF-, IL-1 , IL-6, MCP-1, and MIP-1 , in the remnant livers, and the serum levels of TNF-and IL-1 were substantially reduced in the Ani+Neo group compared with saline group ( < 0.05). The Ani+Neo treatment obviously promoted liver regeneration as indicated by the liver weights and Ki-67 labeling index ( < 0.05). The serum albumin and -GT levels and liver neutrophil infiltration also significantly improved in the Ani+Neo group ( < 0.05) compared with the saline group. Conclusions. These results demonstrate that the combined anisodamine and neostigmine treatment is able to improve the liver regeneration in rats with OJ by substantially alleviating the inflammatory response