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- De Bruyne, Elke, et al.
(författare)
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IGF-1 suppresses Bim expression in multiple myeloma via epigenetic and posttranslational mechanisms
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 115:12, s. 2430-2440
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Tidskriftsartikel (refereegranskat)abstract
- Insulin-like growth factor-1 (IGF-1) is an important growth and survival factor in multiple myeloma (MM). Here, we demonstrate that IGF-1 induces significant down-regulation of the proapoptotic BH3-only protein Bim in MM cells. Reduced Bim levels by RNA interference (RNAi) protected cells from drug-induced cell death. The IGF-1-mediated down-regulation of Bim was the result of (1) reduced transcription by activation of the Akt pathway and inactivation of the transcription factor FoxO3a, (2) increased proteasome-mediated degradation of the Bim extra-long protein by activation of the mitogen-activated protein kinase pathway, and (3) epigenetic regulation of both the Bim and the FoxO3a promoter. Treatment of cells with the histone deacetylase inhibitor LBH589 resulted in a clear up-regulation in the expression of Bim. Furthermore, the methylation inhibitor 5-aza-2'deoxycytidine (decitabine) significantly increased the effects of LBH589. On IGF-1 treatment, the Bim promoter region was found to be unmethylated, whereas chromatin immunoprecipitation analysis of the IGF-1-treated cells showed both a reduced histone H3 tail Lys9 (H3K9) acetylation and an increased H3K9 dimethylation, which contributed actively to its silencing. These data identify a new mechanism in the IGF-1-dependent survival of MM cells and emphasize the need for IGF-1-targeted drug therapy.
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- Hillen, M., et al.
(författare)
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The evolved circumbinary disk of AC Herculis : a radiative transfer, interferometric, and mineralogical study
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 578
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Tidskriftsartikel (refereegranskat)abstract
- Context. Many post-asymptotic giant branch (post-AGB) stars in binary systems have an infrared (IR) excess arising from a dusty circumbinary disk. The disk formation, current structure, and further evolution are, however, poorly understood. Aims. We aim to constrain the structure of the circumstellar material around the post-AGB binary and RV Tauri pulsator AC Her. We want to constrain the spatial distribution of the amorphous and of the crystalline dust. Methods. We present very high-quality mid-IR interferometric data that were obtained with the MIDI / VLTI instrument. We analyze the MIDI visibilities and di ff erential phases in combination with the full spectral energy distribution, using the MCMax radiative transfer code, to find a good structure model of AC Her's circumbinary disk. We include a grain size distribution and midplane settling of dust self-consistently in our models. The spatial distribution of crystalline forsterite in the disk is investigated with the mid-IR features, the 69 mu m band and the 11.3 mu m signatures in the interferometric data. Results. All the data are well fitted by our best model. The inclination and position angle of the disk are precisely determined at i = 50 +/- 8 degrees and PA = 305 +/- 10 degrees. We firmly establish that the inner disk radius is about an order of magnitude larger than the dust sublimation radius. The best-fit dust grain size distribution shows that significant grain growth has occurred, with a significant amount of mm-sized grains now being settled to the midplane of the disk. A large total dust mass >= 10(-3) M-circle dot is needed to fit the mm fluxes. By assuming alpha(turb) = 0 : 01, a good fit is obtained with a small grain size power law index of 3.25, combined with a small gas / dust ratio <= 10. The resulting gas mass is compatible with recent estimates employing direct gas diagnostics. The spatial distribution of the forsterite is di ff erent from the amorphous dust, as more warm forsterite is needed in the surface layers of the inner disk. Conclusions. The disk in the ACHer system is in a very evolved state, as shown by its small gas/dust ratio and large inner hole. Mid-IR interferometry o ff ers unique constraints, complementary to mid-IR features, for studying the mineralogy in disks. A better uv coverage is needed to constrain in detail the distribution of the crystalline forsterite in the disk of ACHer, but we find strong similarities with the protoplanetary disk HD 100546.
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- Sábio, Rafael M., et al.
(författare)
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Near-Infrared Luminescence from Visible-Light-Sensitized Ruthenium(II)-Neodymium(III) Heterobimetallic Bridged Complexes Containing Alkoxy(silyl) Functional Groups
- 2020
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Ingår i: Journal of the Brazilian Chemical Society. - : Sociedade Brasileira de Quimica (SBQ). - 0103-5053 .- 1678-4790. ; 31:4, s. 694-702
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Tidskriftsartikel (refereegranskat)abstract
- New infrared emitting d-f (ruthenium(II)–neodymium(III)) heterobimetallic complexes with alkoxy(silyl) functional groups have been prepared. Visible excitation evidenced energy transfer processes from the ruthenium(II) donor to neodymium(III) acceptors leading to infrared emission. Energy transfer rates (kEnT) and efficiency of energy transfer (ηEnT) are, respectively, 0.61 × 107 s-1 and 44% for RuL1–NdL3 complex. Larger values of kEnT (3.04 × 107 s-1) and ηEnT (84%) were detected for RuL2–NdL4 complex. RuL1–NdL3 and RuL2–NdL4 complexes were fully characterized by elementary analysis (EA), mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT-Raman). Total correlation spectroscopy (TOCSY1D), 1H{13C} heteronuclear single quantum correlation (HSQC) and 1H{13C} heteronuclear multiple bond correlation (HMBC) nuclear magnetic resonance (NMR) analyses were also carried out to characterize NdL3 and RuL1–NdL3 complexes. The presence of trialkoxysilyl-substituted ligands would allow further grafting onto any silica or silicated surface aiming at applications as new luminescent near infrared (NIR)-emitting biosensors or biomarkers.
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