4,074 research outputs found

    Epigenetic silencing of SOCS3 expression contributes to fibrosis in Crohn’s disease

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    Identified risk polymorphisms affecting the Jak-STAT3 pathway in patients with Crohn’s disease could affect TGF-β1 and collagen I expression and in the pathway’s negative regulator, SOCS3. Genetic factors, however, account for only ~25% of disease. Epigenetic events also shape gene expression. Recent experiments showed that autocrine IL-6 production in mesenchymal cells, subepithelial myofibroblasts (SEMF) and muscle cells, of patients with fibrostenotic Crohn’s disease causes sustained Jak-STAT3 activity, excess TGF-β1 and Collagen I production and fibrosis. SOCS3 paradoxically decreased in these cells. We now identify epigenetic mechanisms that silence SOCS3 expression in SEMF of patients with fibrostenotic Crohn’s disease. In a previous experiment, using isolated SEMF of normal ileum and affected ileum from patients with each Crohn’s phenotype, inflammatory (Montreal B1), fibrostenotic (B2) and penetrating (B3), we confirmed decreased SOCS3 protein levels were unique to B2 patients. Expression of miR-19b increased in SEMF of affected ileum. SOCS3 transcriptional activity decreased after transfection of miR-19b mimic and increased when antagomiR-19b was expressed. Epigenetic silencing of SOCS3 in ileal SEMF of patients with fibrostenotic Crohn’s disease occurs by increased miR-19b mediated inhibition of SOCS3

    A near infrared spectroscopic study of the interstellar gas in the starburst core of M82

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    Researchers used the McDonald Observatory Infrared Grating Spectrometer, to complete a program of spatially resolved spectroscopy of M82. The inner 300 pc of the starburst was observed with 4 inch (50 pc) resolution. Complete J, H and K band spectra with resolution 0.0035 micron (lambda/delta lambda=620 at K) were measured at the near-infrared nucleus of the galaxy. Measurements of selected spectral features including lines of FeII, HII and H2 were observed along the starburst ridge-line, so the relative distribution of the diagnostic features could be understood. This information was used to better define the extinction towards the starburst region, the excitation conditions in the gas, and to characterize the stellar populations there

    Complete Journal Spring 1984

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    For historical reasons we have uploaded PDF files for volumes previously published in paper form. Attached you will find the entire volume 1, no. 1 issue from Spring 1984

    Uranium-series dating of corals from the southwest Pacific

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    The uranium-series technique is based on the observation that carbonates precipitating in nature, in particular corals and oolites, show an initial disequilibrium between Th²³⁰ and its parent U²³⁸. The amount of Th²³⁰ initially present in a coral is negligible in comparison to that subsequently generated by the radioactive decay of uranium. If the system remains closed then the ratio of Th²³⁰ to U²³⁸ is a simple function of time. Because there is a 15 percent excess of U²³⁴ to U²³⁸ in sea water this has to be taken into account when determining the age. Corals from New Guinea, the Loyalty Islands, and the east coast of Australia were provided for dating. The New Guinea corals, from the Huon Peninsula, had been dated previously, and so they provided a check on the reliability of the techniques used in this study. With one exception the ages from this study are within the error limits placed on the original ages. The one sample that does not agree is shown to have a high proportion-of void-filling low-Mg calcite cement. Corals from the Capricorn Group and Hayman Island within the Great Barrier Reef province show relatively young ages. One coral recovered by drilling at a depth of 17m on the Hayman Island reef indicates that the time of recolonization of the reef towards the end of the Holocene transgression is about 8,300 yr B.P. Coral samples below a marked discontinuity at a depth of about 20m are extensively recrystallized. Ages of corals from the Inner Barrier of New South Wales show that this feature 'formed during the last inter-glacial at about 120,000 yr B.P. The ages suggest that there were two periods of high sea level at about this time. Ages from reef terraces 2-6m above present sea level from three islands of the Loyalty Archipelago show the varying degrees of uplift of these islands. Corals from +2m on Beautemps-Beaupre are older than 200,000 yr B.P., while a coral at +6.5m from Ouvea gave an age of 117,000 ± 6,000 yr B.P. Ages from the +2m terrace on Lifou support the interpretation of a relatively high sea level at about 180,000 yr B.P. Ages of corals from a slightly raised fringing reef around Mud Island, Moreton Bay indicate a sea level about one metre higher than present during the interval 4,000 - 6,000 yrs B.P. This slightly higher sea level could have been the result of a changing.tidal regime within the bay

    A stochastic vortex structure method for interacting particles in turbulent shear flows

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    In a recent study, we have proposed a new synthetic turbulence method based on stochastic vortex structures (SVSs), and we have demonstrated that this method can accurately predict particle transport, collision, and agglomeration in homogeneous, isotropic turbulence in comparison to direct numerical simulation results. The current paper extends the SVS method to non-homogeneous, anisotropic turbulence. The key element of this extension is a new inversion procedure, by which the vortex initial orientation can be set so as to generate a prescribed Reynolds stress field. After validating this inversion procedure for simple problems, we apply the SVS method to the problem of interacting particle transport by a turbulent planar jet. Measures of the turbulent flow and of particle dispersion, clustering, and collision obtained by the new SVS simulations are shown to compare well with direct numerical simulation results. The influence of different numerical parameters, such as number of vortices and vortex lifetime, on the accuracy of the SVS predictions is also examined