Supermassive Black Hole Binaries: The Search Continues

Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.Comment: 17 pages, 4 figures. To appear in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Inhibitory effects of endogenous and exogenous interferon-γ on bronchial hyperresponsiveness, allergic inflammation and T-helper 2 cytokines in Brown–Norway rats

Interferon-γ (IFN-γ) is an important cytokine involved in the regulation of allergen-induced immune responses. We examined the role of IFN-γ in a Brown–Norway rat model of bronchial hyperresponsiveness (BHR) and airway eosinophilia, and its effects on the mRNA expression of T helper type 1 (Th1)/Th2 cytokine. Ovalbumin (OA)-sensitized animals were given either exogenous IFN-γ (105 U/rat over 3 days, intraperitoneally) or anti-IFN-γ blocking antibody (DB-1 0·3 mg/rat, intravenously) prior to exposure to OA aerosol and were studied 18–24 hr later. In sensitized animals, OA induced significant BHR, accumulation of eosinophils, T lymphocytes and neutrophils in bronchoalveolar lavage (BAL) fluid, and also increased eosinophils and CD8+ T cells in the airways. Exogenous IFN-γ attenuated allergen-induced BHR (P<0·02, compared with sham-treated animals) together with a significant reduction in eosinophil and neutrophil numbers in BAL fluid (P<0·005), and eosinophils and CD8+ T cells in airways (P<0·05). By contrast, anti-IFN-γ antibody increased airway CD4+ T cells and BHR. Using reverse transcriptase–polymerase chain reaction, significant increases in Th2 [interleukin-4 (IL-4), IL-5 and IL-10], and IFN-γ cytokine mRNA were found in the lungs of sensitized and OA-exposed animals, while exogenous IFN-γ significantly suppressed IL-4, IL-5 and IL-10 mRNA expression, and anti-IFN-γ antibody increased IL-4 and IL-5 mRNA expression. These results indicate that Th1 effects, such as those mediated by IFN-γ, play a down-regulatory role to suppress the Th2 responses associated with allergen-induced BHR and eosinophilic inflammation