24 research outputs found

    Multi-wavelength Stellar Polarimetry of the Filamentary Cloud IC5146: I. Dust Properties

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    We present optical and near-infrared stellar polarization observations toward the dark filamentary clouds associated with IC5146. The data allow us to investigate the dust properties (this paper) and the magnetic field structure (Paper II). A total of 2022 background stars were detected in RcR_{c}-, ii'-, HH-, and/or KK-bands to AV25A_V \lesssim 25 mag. The ratio of the polarization percentage at different wavelengths provides an estimate of λmax\lambda_{max}, the wavelength of peak polarization, which is an indicator of the small-size cutoff of the grain size distribution. The grain size distribution seems to significantly change at AVA_V \sim 3 mag, where both the average and dispersion of PRc/PHP_{R_c}/P_{H} decrease. In addition, we found λmax\lambda_{max} \sim 0.6-0.9 μ\mum for AV>2.5A_V>2.5 mag, which is larger than the \sim 0.55 μ\mum in the general ISM, suggesting that grain growth has already started in low AVA_V regions. Our data also reveal that polarization efficiency (PE Pλ/AV\equiv P_{\lambda}/A_V) decreases with AVA_V as a power-law in RcR_c-, ii'-, and KK-bands with indices of -0.71±\pm0.10, -1.23±\pm0.10 and -0.53±\pm0.09. However, HH-band data show a power index change; the PE varies with AVA_V steeply (index of -0.95±\pm0.30) when AV<2.88±0.67A_V < 2.88\pm0.67 mag but softly (index of -0.25±\pm0.06) for greater AVA_V values. The soft decay of PE in high AVA_V regions is consistent with the Radiative Aligned Torque model, suggesting that our data trace the magnetic field to AV20A_V \sim 20 mag. Furthermore, the breakpoint found in HH-band is similar to the AVA_V where we found the PRc/PHP_{R_c}/P_{H} dispersion significantly decreased. Therefore, the flat PE-AVA_V in high AVA_V regions implies that the power index changes result from additional grain growth.Comment: 31 pages, 17 figures, and 3 tables; accepted for publication in Ap

    Pedigree of family 2048 with Stargardt.

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    <p>Solid symbols indicated affected individuals. Open symbols indicated unaffected individuals and arrow indicates the proband.</p

    Topological organization of ABCA4 and conservation analysis.

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    <p>(A) Protein alignment showed conservation of residues ABCA4 Y808X and G607R across nine species. These two mutations occured at an evolutionarily conserved amino acid. The ABCA4 mutation G607R occured in the NBD1 while Y808X occured in the disc lumen region between TMD1. (B) Topological organization of ABCA4 in the disc membrane was shown. The domain organization included exocytoplamic domain (ECD), nucleotide binding domain (NBD) and transmembrane domain (TMD).</p

    Representative photographs of patients of family 2048.

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    <p>(A) Fundus photographs showing pigment mottling and yellow-white flecks in both maculae. (B) Fluorescein angiography (FA) images showing the hyperfluorescent flecks extended to the midperipheral retina and fluorescence blocking by the pigment mottling in the mcular. (C) mfERG records showing severe depressed central waveform and significant paracentral/pereferral loss of retinal response. (D) Macular OCTs showing hyper-reflective deposits within the RPE layer and the level of the outer segments of the photoreceptors, thinning of the retinal outer layers and enhanced choroidal reflectivity associated with overlying atrophic retina.</p

    Iodine and GPXs involved in Thyroid Hormones Biosynthesis.

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    <p>The serum sodium iodide is transported into the thyrocyte and then iodine is incorporated into the thyroglobulin molecule (Tg) in a reaction catalyzed by the hemoprotein thyroid peroxidase (TPO). In this reaction, H<sub>2</sub>O<sub>2</sub> generated by the NADPH-dependent thyroxidase (ThOx) is required as substrate by TPO for the iodination and coupling of tyrosyl residues in Tg. Then, thyroid hormones triiodothyronine (T3) and tetraiodothyronine (T4) are released into the bloodstream. H<sub>2</sub>O<sub>2</sub> used in this reaction decreases the amount of H<sub>2</sub>O<sub>2</sub> that would otherwise be available for damaging oxidation reactions. Selenium-dependent glutathione peroxidase 1 (<i>GPX 1</i>) and other GPX s remove H<sub>2</sub>O<sub>2</sub> from the tissues, also decreasing oxidative damage. (Modified from: J. Köhrle <i>et al</i>. Selenium, the thyroid, and the endocrine system. Endocrine Reviews, December 2005, 26(7):944–984; Lyn Patrick, ND. Iodine: deficiency and therapeutic considerations. Alternative Medicine Review, 2008, 13(2):116–127).</p

    Mutation identification of <i>ABCA4</i> gene.

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    <p>Electropherogram analysis of <i>ABCA4</i> in family 2048 showing the compound heterozygous mutations (c.C2424G and c.G1819A) co-segregated with the phenotype. II1 and II2 patients harbored compound heterozygous c.C2424G and c.G1819A mutations of the <i>ABCA4</i> gene. c.C2424G mutation was carried by the mother I2 while c.G1819A mutation was carried by the father I1.</p