337 research outputs found

    Extragalactic Results from the Infrared Space Observatory

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    More than a decade ago the IRAS satellite opened the realm of external galaxies for studies in the 10 to 100 micron band and discovered emission from tens of thousands of normal and active galaxies. With the 1995-1998 mission of the Infrared Space Observatory the next major steps in extragalactic infrared astronomy became possible: detailed imaging, spectroscopy and spectro-photometry of many galaxies detected by IRAS, as well as deep surveys in the mid- and far- IR. The spectroscopic data reveal a wealth of detail about the nature of the energy source(s) and about the physical conditions in galaxies. ISO's surveys for the first time explore the infrared emission of distant, high-redshift galaxies. ISO's main theme in extragalactic astronomy is the role of star formation in the activity and evolution of galaxies.Comment: 106 pages, including 17 figures. Ann.Rev.Astron.Astrophys. (in press), a gzip'd pdf file (667kB) is also available at http://www.mpe.mpg.de/www_ir/preprint/annrev2000.pdf.g

    Forming a three-dimensional porous organic network via solid-state explosion of organic single crystals

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    Solid-state reaction of organic molecules holds a considerable advantage over liquid-phase processes in the manufacturing industry. However, the research progress in exploring this benefit is largely staggering, which leaves few liquid-phase systems to work with. Here, we show a synthetic protocol for the formation of a three-dimensional porous organic network via solid-state explosion of organic single crystals. The explosive reaction is realized by the Bergman reaction (cycloaromatization) of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene. The origin of the explosion is systematically studied using single-crystal X-ray diffraction and differential scanning calorimetry, along with high-speed camera and density functional theory calculations. The results suggest that the solid-state explosion is triggered by an abrupt change in lattice energy induced by release of primer molecules in the 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene crystal lattice

    Immunological predictors of CD4+ T cell decline in antiretroviral treatment interruptions

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    <p>Abstract</p> <p>Background</p> <p>The common response to stopping anti-HIV treatment is an increase of HIV-RNA load and decrease in CD4<sup>+</sup>, but not all the patients have similar responses to this therapeutic strategy. The aim was to identify predictive markers of CD4<sup>+ </sup>cell count declines to < 350/ΞΌL in CD4-guided antiretroviral treatment interruptions.</p> <p>Methods</p> <p>27 HIV-infected patients participated in a prospective multicenter study in with a 24 month follow-up. Patients on stable highly active antiretroviral therapy (HAART), with CD4<sup>+ </sup>count > 600/ΞΌL, and HIV-RNA < 50 copies/ml for at least 6 months were offered the option to discontinue antiretroviral therapy. The main outcome was a decline in CD4<sup>+ </sup>cell count to < 350/ΞΌL.</p> <p>Results</p> <p>After 24 months of follow-up, 16 of 27 (59%) patients (who discontinued therapy) experienced declines in CD4<sup>+ </sup>cell count to < 350/ΞΌL. Patients with a CD4<sup>+ </sup>nadir of < 200 cells/ΞΌL had a greater risk of restarting therapy during the follow-up (RR (CI95%): 3.37 (1.07; 10.36)). Interestingly, lymphoproliferative responses to <it>Mycobacterium tuberculosis </it>purified protein derivative (PPD) below 10000 c.p.m. at baseline (4.77 (1.07; 21.12)), IL-4 production above 100 pg/mL at baseline (5.95 (1.76; 20.07)) in PBMC cultured with PPD, and increased IL-4 production of PBMC with p24 antigen at baseline (1.25 (1.01; 1.55)) were associated to declines in CD4<sup>+ </sup>cell count to < 350/ΞΌL.</p> <p>Conclusion</p> <p>Both the number (CD4<sup>+ </sup>nadir) and the functional activity of CD4<sup>+ </sup>(lymphoproliferative response to PPD) predict the CD4<sup>+ </sup>decrease associated with discontinuation of ART in patients with controlled viremia.</p

    Increasing risk of revision due to deep infection after hip arthroplasty: A study on 97,344 primary total hip replacements in the Norwegian Arthroplasty Register from 1987 to 2007

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    Background and purpose Over the decades, improvements in surgery and perioperative routines have reduced the incidence of deep infections after total hip arthroplasty (THA). There is, however, some evidence to suggest that the incidence of infection is increasing again. We assessed the risk of revision due to deep infection for primary THAs reported to the Norwegian Arthroplasty Register (NAR) over the period 1987–2007

    Ultraviolet radiation shapes seaweed communities

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    Spatial Patterns in Herbivory on a Coral Reef Are Influenced by Structural Complexity but Not by Algal Traits

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    Background: Patterns of herbivory can alter the spatial structure of ecosystems, with important consequences for ecosystem functions and biodiversity. While the factors that drive spatial patterns in herbivory in terrestrial systems are well established, comparatively less is known about what influences the distribution of herbivory in coral reefs. Methodology and Principal Findings: We quantified spatial patterns of macroalgal consumption in a cross-section of Ningaloo Reef (Western Australia). We used a combination of descriptive and experimental approaches to assess the influence of multiple macroalgal traits and structural complexity in establishing the observed spatial patterns in macroalgal herbivory, and to identify potential feedback mechanisms between herbivory and macroalgal nutritional quality. Spatial patterns in macroalgal consumption were best explained by differences in structural complexity among habitats. The biomass of herbivorous fish, and rates of herbivory were always greater in the structurally-complex coral-dominated outer reef and reef flat habitats, which were also characterised by high biomass of herbivorous fish, low cover and biomass of macroalgae and the presence of unpalatable algae species. Macroalgal consumption decreased to undetectable levels within 75 m of structurally-complex reef habitat, and algae were most abundant in the structurally-simple lagoon habitats, which were also characterised by the presence of the most palatable algae species. In contrast to terrestrial ecosystems, herbivory patterns were not influenced by the distribution, productivity or nutritional quality of resources (macroalgae), and we found no evidence of a positive feedback between macroalgal consumption and the nitrogen content of algae. Significance: This study highlights the importance of seascape-scale patterns in structural complexity in determining spatial patterns of macroalgal consumption by fish. Given the importance of herbivory in maintaining the ability of coral reefs to reorganise and retain ecosystem functions following disturbance, structural complexity emerges as a critical feature that is essential for the healthy functioning of these ecosystems

    Exosome-Related Multi-Pass Transmembrane Protein TSAP6 Is a Target of Rhomboid Protease RHBDD1-Induced Proteolysis

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    We have previously reported that rhomboid domain containing 1 (RHBDD1), a mammalian rhomboid protease highly expressed in the testis, can cleave the Bcl-2 protein Bik. In this study, we identified a multi-pass transmembrane protein, tumor suppressor activated pathway-6 (TSAP6) as a potential substrate of RHBDD1. RHBDD1 was found to induce the proteolysis of TSAP6 in a dose- and activity-dependent manner. The cleavage of TSAP6 was not restricted to its glycosylated form and occurred in three different regions. In addition, mass spectrometry and mutagenesis analyses both indicated that the major cleavage site laid in the C-terminal of the third transmembrane domain of TSAP6. A somatic cell knock-in approach was used to genetically inactivate the endogenous RHBDD1 in HCT116 and RKO colon cancer cells. Exosome secretion was significantly elevated when RHBDD1 was inactivated in the two cells lines. The increased exosome secretion was verfied through the detection of certain exosomal components, including Tsg101, Tf-R, FasL and Trail. In addition, the elevation of exosome secretion by RHBDD1 inactivation was reduced when TSAP6 was knocked down, indicating that the role of RHBDD1 in regulating exosomal trafficking is very likely to be TSAP6-dependent. We found that the increase in FasL and Trail increased exosome-induced apoptosis in Jurkat cells. Taken together, our findings suggest that RHBDD1 is involved in the regulation of a nonclassical exosomal secretion pathway through the restriction of TSAP6
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