On the Polarization of H-alpha Lines Scattered by Neutral Hydrogen in Active Galactic Nuclei

Raman scattering by atomic hydrogen converts the UV continuum around Ly$\beta$ into optical continuum around H$\alpha$, and the basic atomic physics has been discussed in several works on symbiotic stars. We propose that the same process may operate in active galactic nuclei (AGN) and calculate the linear polarization of the broad emission lines Raman-scattered by a high column neutral hydrogen compnent. The conversion efficiency of the Raman scattering process is discussed and the expected scattered flux is computed using the spectral energy distribution of an AGN given by a typical power law. The high column H {\sc i} component in AGN is suggested by many observations encompassing radio through UV and X-ray ranges. When the neutral hydrogen component with a column density $\sim 10^{22} cm^{-2}$ is present around the active nucleus, it is found that the scattered H$\alpha$ is characterized by a very broad width $\sim 20,000 km/s$ and that the strength of the polarized flux is comparable to that of the electron-scattered flux expected from a conventional unified model of narrow line AGN. The width of the scattered flux is mainly determined by the column density of the neutral scatterers where the total scattering optical depth becomes of order unity. The asymmetry in the Raman scattering cross section around Ly$\beta$ introduces red asymmetric polarized profiles around H$\alpha$. The effects of the blended Ly$\beta$ and O {\sc vi} 1034 doublet are also investigated. We briefly discuss the spectropolarimetric observations performed on the Seyfert galaxy IRAS 110548-1131 and the narrow line radio galaxy Cyg A.Comment: 11 pages, 6 figures, accepted for publication in MNRA

Melittin (MEL) inhibited the HIF-1α protein accumulation induced by the EGF in the CaSki cells.

<p>(A) Dose-dependent effect of MEL on the viability of CaSki cells. Cells were treated with the indicated concentrations of MEL for 24 h. Viability was determined by WST-1 assay. Values represent the means ± SD of triplicate assays. *, <i>p</i><0.05 as compared to untreated control. Results were analyzed using one-way ANOVA. (B) Cells were pretreated with the indicated concentrations of MEL for 30 min, and then induced by EGF treatment for 6 h. (C) Cells were pretreated with the indicated concentrations of MEL for 30 min, and then induced by CoCl₂ treatment for 6 h. Nuclear extracts were subjected to Western blot using antibodies against HIF-1α and HIF-1β.</p

Melittin (MEL) suppressed the EGF-induced migration and angiogenesis in the CaSki cells.

<p>(A and B) CaSki 3×10⁴ cells/ml were mixed with 0.5 ml of Matrigel in the presence or absence of EGF (500 ng/ml) and MEL (1 and 2 µg/ml) in vivo. (C and D) Matrigel migration assay was carried out MEL (1 and 2 µg/ml) in the presence of EGF (20 ng/ml). After 24 h incubation, cells bottom side of filter were fixed, stained and counted. Data represents the means ± SD of three independent experiments. *, <i>p</i><0.05 as compared to EGF-treated control. Results were analyzed using one-way ANOVA.</p

Melittin (MEL) suppressed the EGF-induced HIF-1α protein synthesis by inhibiting the ERK and mTOR/p70S6K signaling pathways in the CaSki cells.

<p>(A) Effect of MEL on EGF-induced signaling leading to the expression of HIF-1α in CaSki cells. CaSki cells were pretreated with the indicated concentrations of MEL for 1 h, followed by incubation with EGF for 30 min. The phosphorylated levels of EGFR, P38, ERK, JNK, Akt, mTOR and p70S6K were determined by Western blot analysis. (B) Effects of MEL and inhibitors on EGF-induced expression of HIF-1α in CaSki cells. CaSki cells were pretreated with MEL, SB203580, SP600125, PD98059, wortmannin, rapamycin for 30 min, and then induced by EGF treatment for 6 h. Nuclear extracts were subjected to Western blot using antibodies against HIF-1α or β-actin. Data represents the means ± SD of three independent experiments. *, <i>p</i><0.05 as compared to EGF-treated control. Results were analyzed using one-way ANOVA.</p