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Search Results: 1 - 10 of 130413 matches for " Stangl V "
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Contrast-enhanced MR imaging of atherosclerosis using citrate-coated superparamagnetic iron oxide nanoparticles: calcifying microvesicles as imaging target for plaque characterization
Wagner S,Schnorr J,Ludwig A,Stangl V
International Journal of Nanomedicine , 2013,
Abstract: Susanne Wagner,1 J rg Schnorr,1 Antje Ludwig,2 Verena Stangl,2 Monika Ebert,1 Bernd Hamm,1 Matthias Taupitz11Department of Radiology, Section of Experimental Radiology, Charité – Universit tsmedizin Berlin, Campus Charité Mitte, and Campus Benjamin Franklin, Berlin, Germany; 2Department of Cardiology, Section of Experimental Cardiology, Charité – Universit tsmedizin Berlin, Campus Charité Mitte, Berlin, GermanyObjective: To evaluate the suitability of citrate-coated very small superparamagnetic iron oxide particles (VSOP) as a contrast agent for identifying inflammation in atherosclerotic lesions using magnetic resonance imaging (MRI).Methods and results: VSOP, which have already been evaluated as a blood pool contrast agent for MR angiography in human clinical trials, were investigated in Watanabe heritable hyperlipidemic rabbits to determine to what extent their accumulation in atherosclerotic lesions is a function of macrophage density and other characteristics of progressive atherosclerotic plaques. In advanced atherosclerotic lesions, a significant MRI signal loss was found within 1 hour after intravenous administration of VSOP at the intended clinical dose of 0.05 mmol Fe/kg. Histological examinations confirmed correlations between the loss of MRI signal in the vessel wall and the presence of Prussian blue-stained iron colocalized with macrophages in the plaque cap, but surprisingly also with calcifying microvesicles at the intimomedial interface. Critical electrolyte magnesium chloride concentration in combination with Alcian blue stain indicates that highly sulfated glycosaminoglycans are a major constituent of these calcifying microvesicles, which may serve as the key molecules for binding VSOP due to their highly complexing properties.Conclusion: Calcifying microvesicles and macrophages are the targets for intravenously injected VSOP in atherosclerotic plaques, suggesting that VSOP-enhanced MRI may render clinically relevant information on the composition and inflammatory activity of progressive atherosclerotic lesions at risk of destabilization.Keywords: atherosclerosis, inflammation, magnetic resonance imaging, iron oxide nanoparticles, glycosaminoglycans, calcifying microvesicles
Contrast-enhanced MR imaging of atherosclerosis using citrate-coated superparamagnetic iron oxide nanoparticles: calcifying microvesicles as imaging target for plaque characterization
Wagner S, Schnorr J, Ludwig A, Stangl V, Ebert M, Hamm B, Taupitz M
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S38702
Abstract: ntrast-enhanced MR imaging of atherosclerosis using citrate-coated superparamagnetic iron oxide nanoparticles: calcifying microvesicles as imaging target for plaque characterization Original Research (660) Total Article Views Authors: Wagner S, Schnorr J, Ludwig A, Stangl V, Ebert M, Hamm B, Taupitz M Published Date February 2013 Volume 2013:8 Pages 767 - 779 DOI: http://dx.doi.org/10.2147/IJN.S38702 Received: 01 October 2012 Accepted: 02 December 2012 Published: 20 February 2013 Susanne Wagner,1 J rg Schnorr,1 Antje Ludwig,2 Verena Stangl,2 Monika Ebert,1 Bernd Hamm,1 Matthias Taupitz1 1Department of Radiology, Section of Experimental Radiology, Charité – Universit tsmedizin Berlin, Campus Charité Mitte, and Campus Benjamin Franklin, Berlin, Germany; 2Department of Cardiology, Section of Experimental Cardiology, Charité – Universit tsmedizin Berlin, Campus Charité Mitte, Berlin, Germany Objective: To evaluate the suitability of citrate-coated very small superparamagnetic iron oxide particles (VSOP) as a contrast agent for identifying inflammation in atherosclerotic lesions using magnetic resonance imaging (MRI). Methods and results: VSOP, which have already been evaluated as a blood pool contrast agent for MR angiography in human clinical trials, were investigated in Watanabe heritable hyperlipidemic rabbits to determine to what extent their accumulation in atherosclerotic lesions is a function of macrophage density and other characteristics of progressive atherosclerotic plaques. In advanced atherosclerotic lesions, a significant MRI signal loss was found within 1 hour after intravenous administration of VSOP at the intended clinical dose of 0.05 mmol Fe/kg. Histological examinations confirmed correlations between the loss of MRI signal in the vessel wall and the presence of Prussian blue-stained iron colocalized with macrophages in the plaque cap, but surprisingly also with calcifying microvesicles at the intimomedial interface. Critical electrolyte magnesium chloride concentration in combination with Alcian blue stain indicates that highly sulfated glycosaminoglycans are a major constituent of these calcifying microvesicles, which may serve as the key molecules for binding VSOP due to their highly complexing properties. Conclusion: Calcifying microvesicles and macrophages are the targets for intravenously injected VSOP in atherosclerotic plaques, suggesting that VSOP-enhanced MRI may render clinically relevant information on the composition and inflammatory activity of progressive atherosclerotic lesions at risk of destabilization.
Decrease of the electric field penetration into the ionosphere due to low conductivity at the near ground atmospheric layer
M. Ampferer, V. V. Denisenko, W. Hausleitner, S. Krauss, G. Stangl, M. Y. Boudjada,H. K. Biernat
Annales Geophysicae (ANGEO) , 2010,
Abstract: It is well known that lithospheric electromagnetic emissions are generated before earthquakes occurrence. In our study, we consider the physical penetration mechanism of the electric field from the Earth's surface, through the atmosphere-ionosphere layers, and until its detection in space by satellites. A simplified approach is investigated using the electric conductivity equation, i.e., σ· Φ)=0 in the case of a vertical inclination of the geomagnetic field lines. Particular interest is given to the conductivity profile near the ground and the electric field distribution at the Earth's surface. Our results are discussed and compared to the models of Pulinets et al. (2003) and Denisenko et al. (2008). It is shown that the near ground atmospheric layer with low conductivity decreases the electric field penetration into the ionosphere. The model calculations have demonstrated that the electric field of lithospheric origin is too weak to be observed at satellite altitudes.
Historical floods in the Dutch Rhine Delta
R. Glaser,H. Stangl
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2003,
Abstract: Historical records provide direct information about the climatic impact on society. Especially great natural disasters such as river floods have been for long attracting the attention of humankind. Time series for flood development on the Rhine branches Waal, Nederrijn/Lek and IJssel in the Dutch Rhine Delta are presented in this paper. In the case of the Waal it is even possible to compare historical flood frequencies based on documentary data with the recent development reconstructed from standardized instrumental measurements. In brief, we will also discuss various parameters concerning the structure of the flood series and the "human dimension" of natural disaster, i.e. the vulnerability of society when facing natural disasters.
Strain determination in the Si channel above a single SiGe island inside a field effect transistor using nanobeam x-ray diffraction
N. Hrauda,J. J. Zhang,E. Wintersberger,T. Etzelstorfer,J. Stangl,D. Carbone,C. Biasotto,V. Jovanovic,L. K. Nanver,J. Moers,D. Grützmacher,G. Bauer
Physics , 2010,
Abstract: SiGe islands are used to induce tensile strain in the Si channel of Field Effect Transistors to achieve larger transconductance and higher current driveabilities. We report on x-ray diffraction experiments on a single fully-processed and functional device with a TiN+Al gate stack and source, gate, and drain contacts in place. The strain fields in the Si channel were explored using an x-ray beam focused to 400 nm diameter combined with finite element simulations. A maximum in-plane tensile strain of about 1% in the Si channel was found, which is by a factor of three to four higher than achievable for dislocation-free tensile strained Si in state-of-the-art devices.
Detailed Micro Raman Spectroscopy Analysis of Doped Silicon Thin Film Layers and Its Feasibility for Heterojunction Silicon Wafer Solar Cells  [PDF]
Z. P. Ling, J. Ge, R. Stangl, A. G. Aberle, T. Mueller
Journal of Materials Science and Chemical Engineering (MSCE) , 2013, DOI: 10.4236/msce.2013.15A001
Abstract:

Hydrogenated doped silicon thin films deposited using RF (13.56 MHz) PECVD were studied in detail using micro Raman spectroscopy to investigate the impact of doping gas flow, film thickness, and substrate type on the film characteristics. In particular, by deconvoluting the micro Raman spectra into amorphous and crystalline components, qualitative and quantitative information such as bond angle disorder, bond length, film stress, and film crystallinity can be determined. By selecting the optimum doped silicon thin film deposition conditions, and combining our p-doped and n-doped silicon thin films in different heterojunction structures, we demonstrate both (i) an efficient field effect passivation and (ii) further improvement to c-Si/a-Si:H(i) interface defect density with observed improvement in implied open-circuit voltage VOC and minority carrier lifetimes across all injections levels of interest. In particular, the heterojunction structure (a-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(i)/a-Si:H(p)) demonstrates a minority carrier lifetime of 2.4 ms at an injection level of 1015 cm-3, and a high implied open-circuit voltage of 725 mV. Simulation studies reveal a strong dependence of the interface defect density Dit on the heterojunction silicon wafer solar cell performance, affected by the deposition conditions of the overlying doped silicon thin film layers. Using our films, and a fitted Dit of 5 × 1010 cm-2·eV-1

xrayutilities: A versatile tool for reciprocal space conversion of scattering data recorded with linear and area detectors
Dominik Kriegner,Eugen Wintersberger,Julian Stangl
Physics , 2013, DOI: 10.1107/S0021889813017214
Abstract: We present general algorithms to convert scattering data of linear and area detectors recorded in various scattering geometries to reciprocal space coordinates. The presented algorithms work for any goniometer configuration including popular four-circle, six-circle and kappa goniometers. We avoid the use of commonly employed approximations and therefore provide algorithms which work also for large detectors at small sample detector distances. A recipe for determining the necessary detector parameters including mostly ignored misalignments is given. The algorithms are implemented in a freely available open-source package.
Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/AlInSb quantum well structures
S. Stachel,P. Olbrich,C. Zoth,U. Hagner,T. Stangl,C. Karl,P. Lutz,V. V. Bel'kov,S. K. Clowes,T. Ashley,A. M. Gilbertson,S. D. Ganichev
Physics , 2011, DOI: 10.1103/PhysRevB.85.045305
Abstract: We report on the observation of linear and circular magnetogyrotropic photogalvanic effects in InSb/AlInSb quantum well structures. We show that intraband (Drude-like) absorption of terahertz radiation in the heterostructures causes a dc electric current in the presence of an in-plane magnetic field. The photocurrent behavior upon variation of the magnetic field strength, temperature and wavelength is studied. We show that at moderate magnetic fields the photocurrent exhibits a typical linear field dependence. At high magnetic fields, however, it becomes nonlinear and inverses its sign. The experimental results are analyzed in terms of the microscopic models based on asymmetric relaxation of carriers in the momentum space. We demonstrate that the observed nonlinearity of the photocurrent is caused by the large Zeeman spin splitting in InSb/AlInSb structures and an interplay of the spin-related and spin-independent roots of the magnetogyrotropic photogalvanic effect.
Circulating Angiogenic Factors in Patients with Thromboangiitis Obliterans
Bernd Hewing, Verena Stangl, Karl Stangl, Kathrin Enke-Melzer, Gert Baumann, Antje Ludwig
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034717
Abstract: Background Thromboangiitis obliterans (TAO, also known as Buerger's disease) is a non-atherosclerotic inflammatory vascular disease that primarily affects arteries in the extremities of young adult smokers. Since the etiology of TAO is still unknown, therapeutic options are limited. Recent attempts in therapeutic angiogenesis have been promising. Therefore, the aim of our study was to evaluate angiogenic processes and factors including circulating progenitor cells in TAO. Methodology/Principal Findings TAO patients with critical limb ischemia and age- and gender-matched nonsmokers and smokers without cardiovascular disease (n = 12 in each group) were enrolled in the study. Flow cytometric analysis of peripheral blood showed significantly decreased levels of circulating CD45dimCD34+ progenitor cells in TAO patients and in smokers compared to nonsmokers. In contrast to both control groups, the proportion of CD45dimCD34+ progenitor cells co-expressing VEGF receptor-2 (VEGFR2) was significantly elevated in TAO patients. Enzyme-linked immunosorbent assay (ELISA) of common angiogenic factors (such as VEGF) did not clearly point to pro- or antiangiogenic conditions in serum or plasma of TAO patients. Serum of TAO patients and controls was evaluated in proliferation, migration (scratch assay) and spheroid sprouting assays using human umbilical vein endothelial cells (HUVECs). Serum of TAO patients exhibited a diminished sprouting capacity of HUVECs compared to both control groups. Proliferation and migration of endothelial cells were impaired after treatment with serum of TAO patients. Conclusion Levels of circulating progenitor cells were altered in TAO patients compared to healthy nonsmokers and smokers. Furthermore, serum of TAO patients exhibited an antiangiogenic activity (impaired endothelial cell sprouting, migration and proliferation) on endothelial cells, which may contribute to vascular pathology in this patient population.
Renal Denervation Therapy: Indications and Success Factors
Karl Stangl,Verena Stangl,Marius Schwerg,Julia Searle,Martin M?ckel
Conference Papers in Science , 2013, DOI: 10.1155/2013/804764
Abstract: Arterial hypertension is a common and an increasing health care problem. In Germany and other Western countries, prevalence rates are as high as 50%. Of these, 13% of patients suffer from refractory hypertension, where the target blood pressure is not achievable with >3 antihypertensive substances. Renal denervation therapy (RDT) is a relatively new, catheterization-based intervention to treat patients with refractory hypertension. The rationale of RDT is the mechanical destruction with high frequency ablation of renal sympathetic fibers, which can be easily accessed via the renal artery. The first clinical trials evaluating effect and safety of the procedure have been promising, and RDT is being routinely used in specialized centers. 1. Introduction Arterial hypertension is one of the most important and prevalent risk factors for cardiovascular diseases. In Germany and other Western industrialized countries, a double-digit million number of patients suffer from arterial hypertension. Unfortunately, in the past, perception of arterial hypertension as a major risk factor was poor, as expressed in citations by John Hay: “The greatest danger to a man with high blood pressure lies in its discovery, because then some fool is certain to try and reduce it” [1] and Paul D White in 1931: “The treatment of the hypertension itself is a difficult and almost hopeless task … we know the hypertension may be an important compensatory mechanism” (Paul D White. Heart Disease (1st edn.) McMillan, New York (1931)). This perception was of political relevance: US President Franklin Delano Roosevelt died “unexpecteditly” at the end of World War II from a hemorrhagic stroke caused by exorbitantly increased arterial blood pressure as recorded by his personal physician during the Yalta Conference. Since then, the attitude towards arterial hypertension has changed. Today, we know that the blood pressure significantly correlates with the incidence of cardiovascular events; reduction of only 20 and 10?mmHg in systolic and diastolic blood pressure, respectively, results in an almost 50% decrease of death caused by cardiovascular events, independent of the patient’s age [2]. Today, cut-off values for a detailed definition of hypertension are available. Gold standard is the 24-hour blood pressure measurement, which should not exceed 125–130/80?mmHg. Most clinical trials use the office blood pressure, where the threshold is set at 140/90?mmHg. Cut-off values for day, night, and home measurement have also been defined [3]. Using these cut-offs, the prevalence of arterial hypertension in
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