Todd L. Duncan

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We have identified from mouse the first mammalian beta-carotene 15,15'-dioxygenase (beta-CD), a crucial enzyme in development and metabolism that governs the de novo entry of vitamin A from plant-derived precursors. beta-CD is related to the retinal pigment epithelium-expressed protein RPE65 and belongs to a diverse family that includes the plant(More)
PURPOSE The inflammatory response of the retinal pigment epithelium (RPE) is implicated in the pathogenesis of age-related macular degeneration. The microRNAs miR-146a and miR-146b-5p can regulate the inflammatory process by attenuating cytokine signaling via the nuclear factor-κB pathway. The aim of the present study is to investigate the expression of(More)
PURPOSE MicroRNAs (miRNAs) are important regulators of many cellular functions due to their ability to target mRNAs for degradation or translational inhibition. Previous studies have reported that the expression of microRNA-9 (miR-9) is regulated by retinoic acid and reactive oxygen species (ROS). We have previously shown that N-(4-hydroxyphenyl)-retinamide(More)
Even after over 150 years of discussion, the interpretation of the second law of thermodynamics continues to be a source of confusion and controversy in physics. This confusion has been accentuated by recent challenges to the second law and by the difficulty in many cases of clarifying which formulation is threatened and how serious the implications of a(More)
In the search for a possible Drosophila melanogaster homolog of interphotoreceptor retinoid-binding protein (IRBP), a approximately 140-kDa retinoid- and fatty acid-binding glycoprotein found in vertebrates, the 110,000 g supernatant fraction prepared from homogenates of fly heads was analyzed for the presence of proteins capable of binding radiolabeled(More)
ARPE-19, a human retinal pigment epithelial (RPE) cell line, has been widely used in studies of RPE function as well as gene expression. Here, we report the novel finding that N-(4-hydroxyphenyl)retinamide (fenretinide), a synthetic retinoic acid derivative and a potential chemopreventive agent against cancer, induced the differentiation of ARPE-19 cells(More)
Activins, a subgroup of the transforming growth factor-beta (TGF-beta) superfamily, have been extensively studied in vertebrates for their roles in growth and development. However, activins are not thought to be expressed in invertebrates. The identification of the first invertebrate activin gene is reported here. A genomic clone representing 102 F region(More)
Retinyl esters play an important role in the visual cycle because they are involved in regeneration of 11-cis-retinal for use in rhodopsin formation. In the present study, retinyl ester concentrations were significantly elevated in eyes and livers of mice homozygous for the vitiligo mutation (mivit/mivit). Vitiligo mice demonstrate a slowly progressing(More)
Results obtained in a previous study showed that, compared with a normal eyecup preparation, the amount of rhodopsin regenerated and the rate at which it was resynthesized after bleaching were reduced by about 50% when the skate retina was detached from its pigment epithelium (RPE) and replaced immediately on the apical surface of the RPE (Sun and Ripps,(More)