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  • 1
    Language: German
    In: Praxis, 22 August 2012, Vol.101(17), pp.1131-3
    Keywords: Brachiocephalic Trunk -- Diagnostic Imaging ; Image Interpretation, Computer-Assisted -- Methods ; Ultrasonography, Doppler, Color -- Methods
    ISSN: 1661-8157
    E-ISSN: 16618165
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  • 2
    Language: German
    In: Praxis, 08/2012, Vol.101(16), pp.1010-1011
    Description: Ultrasound-based technologies are competing more and more success-fully against computerized tomography and magnetic resonance based imaging procedures. This thanks to technological improvements as well as accumulating evidence, stemming from properly conducted controlled clinical studies. The reduced cost and radiation safety issues are additional arguments in its favor. This article reviews new developments in ultrasound medicine as applied to the liver. Emphasis lies on new data related to contrast-ultrasound (Sulphur Hexafluoride SonoVue®) which allows a dynamic analysis of liver perfusion and hence improved characterization of focal liver lesions, such as metastases of extrahepatic tumors, regenerative nodules in patients with liver cirrhosis, focal nodular hyperplasia, hepatocellular carcinoma, liver hemangioma, liver adenoma and or focal hypo-respectively hypersteatosis. This article also deals with important new techniques, which allow assessment of liver stiffness such as transient elastography (Fibroscan), ARFI (Acoustic Radiation Force Impulse) or real-time-tissue elastography. These new techniques will help us to assess and quantify the levels of liver steatosis with more precision and permit accurate follow-up measurements.
    Keywords: Phospholipids ; Sulfur Hexafluoride ; Contrast Media -- Administration & Dosage ; Elasticity Imaging Techniques -- Methods ; Image Enhancement -- Methods ; Image Interpretation, Computer-Assisted -- Methods ; Liver -- Blood Supply ; Liver Diseases -- Diagnostic Imaging ; Liver Neoplasms -- Diagnostic Imaging;
    ISSN: 1661-8157
    E-ISSN: 1661-8165
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  • 3
    Language: German
    In: Praxis, 03/2012, Vol.101(7), pp.449-450
    ISSN: 1661-8157
    E-ISSN: 1661-8165
    Source: Hogrefe & Huber (via CrossRef)
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  • 4
    Language: English
    In: Plant physiology, September 2014, Vol.166(1), pp.190-201
    Description: Freezing can severely damage plants, limiting geographical distribution of natural populations and leading to major agronomical losses. Plants native to cold climates acquire increased freezing tolerance during exposure to low nonfreezing temperatures in a process termed cold acclimation. This involves many adaptative responses, including global changes in metabolite content and gene expression, and the accumulation of cold-regulated (COR) proteins, whose functions are largely unknown. Here we report that the chloroplast proteins COR15A and COR15B are necessary for full cold acclimation in Arabidopsis (Arabidopsis thaliana). They protect cell membranes, as indicated by electrolyte leakage and chlorophyll fluorescence measurements. Recombinant COR15 proteins stabilize lactate dehydrogenase during freezing in vitro. However, a transgenic approach shows that they have no influence on the stability of selected plastidic enzymes in vivo, although cold acclimation results in increased enzyme stability. This indicates that enzymes are stabilized by other mechanisms. Recombinant COR15 proteins are disordered in water, but fold into amphipathic α-helices at high osmolyte concentrations in the presence of membranes, a condition mimicking molecular crowding induced by dehydration during freezing. X-ray scattering experiments indicate protein-membrane interactions specifically under such crowding conditions. The COR15-membrane interactions lead to liposome stabilization during freezing. Collectively, our data demonstrate the requirement for COR15 accumulation for full cold acclimation of Arabidopsis. The function of these intrinsically disordered proteins is the stabilization of chloroplast membranes during freezing through a folding and binding mechanism, but not the stabilization of chloroplastic enzymes. This indicates a high functional specificity of these disordered plant proteins.
    Keywords: Acclimatization ; Freezing ; Arabidopsis -- Physiology ; Arabidopsis Proteins -- Metabolism ; Intracellular Membranes -- Metabolism
    ISSN: 00320889
    E-ISSN: 1532-2548
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  • 5
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 18 March 2014, Vol.111(11), pp.4019-24
    Description: The mechanisms by which gene expression is regulated by oxygen are of considerable interest from basic science and therapeutic perspectives. Using mass spectrometric analyses of Saccharomyces cerevisiae ribosomes, we found that the amino acid residue in closest proximity to the decoding center, Pro-64 of the 40S subunit ribosomal protein Rps23p (RPS23 Pro-62 in humans) undergoes posttranslational hydroxylation. We identify RPS23 hydroxylases as a highly conserved eukaryotic subfamily of Fe(II) and 2-oxoglutarate dependent oxygenases; their catalytic domain is closely related to transcription factor prolyl trans-4-hydroxylases that act as oxygen sensors in the hypoxic response in animals. The RPS23 hydroxylases in S. cerevisiae (Tpa1p), Schizosaccharomyces pombe and green algae catalyze an unprecedented dihydroxylation modification. This observation contrasts with higher eukaryotes, where RPS23 is monohydroxylated; the human Tpa1p homolog OGFOD1 catalyzes prolyl trans-3-hydroxylation. TPA1 deletion modulates termination efficiency up to ∼10-fold, including of pathophysiologically relevant sequences; we reveal Rps23p hydroxylation as its molecular basis. In contrast to most previously characterized accuracy modulators, including antibiotics and the prion state of the S. cerevisiae translation termination factor eRF3, Rps23p hydroxylation can either increase or decrease translational accuracy in a stop codon context-dependent manner. We identify conditions where Rps23p hydroxylation status determines viability as a consequence of nonsense codon suppression. The results reveal a direct link between oxygenase catalysis and the regulation of gene expression at the translational level. They will also aid in the development of small molecules altering translational accuracy for the treatment of genetic diseases linked to nonsense mutations.
    Keywords: 2-Oxoglutarate Oxygenase ; Hypoxia ; Nonsense Readthrough ; Ribosomal Hydroxylation ; Translation ; Protein Biosynthesis -- Physiology ; Protein Processing, Post-Translational -- Physiology ; Ribosomal Proteins -- Metabolism ; Ribosomes -- Physiology
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 6
    In: Perspectives on Politics, 2012, Vol.10(2), pp.418-421
    Description: We live in a world laced with forms of political violence. Kristen Renwick Monroe's latest work develops an interesting social psychological account of the conduct of victims, perpetrators, and bystanders of the most extreme form of violence—genocide. It also employs an interesting narrative approach that contributes to broad methodological discussions in political science about the ways in which subjective experience can best be understood. We have thus invited a diverse group of political scientists and historians to comment on the book's analysis of political violence and on its broader approach to the study of politics.—Jeffrey C. Isaac, Editor
    ISSN: 1537-5927
    E-ISSN: 1541-0986
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  • 7
    Language: English
    In: Biomaterials, 2010, Vol.31(8), pp.2097-2104
    Description: Nanostructured materials provide a new dimension of interaction with biological systems that takes place on a sub-cellular level with a high degree of specificity. In the field of neuroscience the nanoscale corresponds to the size of synapses; the specific connections between brain cells. In this context, diamond-based materials have attracted much attention due to their extreme mechanical and electrical properties and their chemical inertness. Here the suitability of nanodiamond (ND) monolayers to act as a platform for neuronal growth is investigated. Neurons cultured on various ND-coated substrates perform remarkably well, and similar to those grown on standard protein-coated materials with respect to their initial cell attachment, sustained neurite outgrowth, cell-autonomous neuronal excitability and functionality of the resulting electrical networks. ND layering provides an excellent growth substrate on various materials for functional neuronal networks and bypasses the necessity of protein coating, which promises great potential for chronic medical implants.
    Keywords: Diamond ; Electrophysiology ; Nanoparticle ; Neural Network ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 8
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 10 January 2012, Vol.109(2), pp.443-8
    Description: The concept of DNA "repair centers" and the meaning of radiation-induced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here, we provide strong evidence for the existence of repair centers. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double-strand breaks (DSBs) 1 to 2 μm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF/Gy after 2 Gy exposure compared to approximately 64 RIF/Gy after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results. The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances casts considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provides a mechanism that could more accurately address risk dose dependency of ionizing radiation.
    Keywords: Dose-Response Relationship, Radiation ; Breast Neoplasms -- Genetics ; DNA Breaks, Double-Stranded -- Radiation Effects ; DNA Repair -- Physiology ; DNA-Binding Proteins -- Metabolism ; Intracellular Signaling Peptides and Proteins -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 9
    Language: English
    In: SIAM Journal on Numerical Analysis, 2012, Vol.50(6), pp.3231-3258
    Description: In this work, the issue of favorable numerical methods for the space and time discretization of low-dimensional nonlinear Schrödinger equations is addressed. The objective is to provide a stability and error analysis of high-accuracy discretizations that rely on spectral and splitting methods. As a model problem, the time-dependent Gross--Pitaevskii equation arising in the description of Bose--Einstein condensates is considered. For the space discretization pseudospectral methods collocated at the associated quadrature nodes are analyzed. For the time integration high-order exponential operator splitting methods are studied, where the decomposition of the function defining the partial differential equation is chosen in accordance with the underlying spectral method. The convergence analysis relies on a general framework of abstract nonlinear evolution equations and fractional power spaces defined by the principal linear part. Essential tools in the derivation of a temporal global error estimate are further the formal calculus of Lie-derivatives and bounds for iterated Lie-commutators. Numerical examples for higher-order time-splitting pseudospectral methods applied to time-dependent Gross--Pitaevskii equations illustrate the theoretical result.
    Keywords: Nonlinear Schrödinger Equations ; Time-Dependent Gross--Pitaevskii Equations ; Spectral Methods ; Splitting Methods ; Stability ; Error ; Convergence ; 65l05 ; 65m12 ; 65j15
    ISSN: 0036-1429
    E-ISSN: 1095-7170
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  • 10
    Language: German
    In: Praxis, 15 December 2010, Vol.99(25), pp.1580-1
    Keywords: Ultrasonography, Doppler, Color ; Aneurysm, Dissecting -- Diagnostic Imaging ; Aortic Aneurysm -- Diagnostic Imaging ; Carotid Artery Diseases -- Diagnostic Imaging ; Carotid Artery, Common -- Diagnostic Imaging
    ISSN: 1661-8157
    E-ISSN: 16618165
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