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Search Results: 1 - 10 of 6713 matches for " Sven Oliver Eicker "
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The Impact of Experimental Preconditioning Using Vascular Endothelial Growth Factor in Stroke and Subarachnoid Hemorrhage
Sven Oliver Eicker,Moritz Hoppe,Nima Etminan,Stephan Macht
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/948783
Abstract:
The Impact of Experimental Preconditioning Using Vascular Endothelial Growth Factor in Stroke and Subarachnoid Hemorrhage
Sven Oliver Eicker,Moritz Hoppe,Nima Etminan,Stephan Macht,Jason Perrin,Hans-Jakob Steiger,Daniel H?nggi
Stroke Research and Treatment , 2013, DOI: 10.1155/2013/948783
Abstract: Vascular endothelial growth factor (VEGF) stimulating angiogenesis was shown to be a potential novel therapeutic approach for the treatment of ischemic vascular diseases. The goal of the present study was to examine whether transfection of VEGF before occurrence of major stroke (part I) and cerebral vasospasm after experimental subarachnoid hemorrhage (SAH; part II) develops neuroprotective qualities. A total of 25 (part I) and 26 (part II) brains were analyzed, respectively. In part one, a significant reduction of infarct volume in the VEGF-treated stroke animals (43% reduction, ) could be detected. In part two, significant vasospasm was induced in all hemorrhage groups . Analyzing microperfusion, a significant higher amount of perfused vessels could be detected , whereas no significant effect could be detected towards macroperfusion. Histologically, no infarctions were observed in the VEGF-treated SAH group and the sham-operated group. Minor infarction in terms of vasospasm-induced small lesions could be detected in the control vector transduced group and saline-treated group . The present study demonstrates the preconditioning impact of systemic intramuscular VEGF injection in animals after major stroke and induced severe vasospasm after SAH. 1. Introduction Cerebral vasospasm and delayed cerebral ischemia contribute the major part of secondary morbidity and mortality after severe subarachnoid hemorrhage (SAH) [1–5]. Despite the current treatment strategies, the rate of related permanent disability is estimated at 10% to 20% [6–9]. Vascular endothelial growth factor (VEGF) is involved in neurogenesis, inhibition of apoptosis, learning, and memory [10]. It can directly promote neuroprotection, but first of all VEGF is the main factor responsible for angiogenesis whereby an indirect neuroprotection is discussed. VEGF expression is increased during cerebral ischemia in humans and animals [11]. However, endogenous VEGF seems to be insufficient to protect the brain from ischemic injury completely. Interestingly, it could be shown that exogenous administrated VEGF induces angiogenic changes that result in a reduction of cerebral ischemic injury [12, 13]. For this reason VEGF was adopted as a potential novel therapeutic approach for the treatment of ischemic vascular disease, particularly in ischemic stroke [14–18]. The aim of the present experimental study was to examine the effect of systemic overexpression of VEGF prior to stroke and SAH with regard to cerebral infarction, vasospasm, and perfusion. 2. Material and Methods This study was carried out in
In silico design of targeted SRM-based experiments
Nahnsen Sven,Kohlbacher Oliver
BMC Bioinformatics , 2012, DOI: 10.1186/1471-2105-13-s16-s8
Abstract: Selected reaction monitoring (SRM)-based proteomics approaches enable highly sensitive and reproducible assays for profiling of thousands of peptides in one experiment. The development of such assays involves the determination of retention time, detectability and fragmentation properties of peptides, followed by an optimal selection of transitions. If those properties have to be identified experimentally, the assay development becomes a time-consuming task. We introduce a computational framework for the optimal selection of transitions for a given set of proteins based on their sequence information alone or in conjunction with already existing transition databases. The presented method enables the rapid and fully automated initial development of assays for targeted proteomics. We introduce the relevant methods, report and discuss a step-wise and generic protocol and we also show that we can reach an ad hoc coverage of 80 % of the targeted proteins. The presented algorithmic procedure is implemented in the open-source software package OpenMS/TOPP.
The impact of regional and neighbourhood deprivation on physical health in Germany: a multilevel study
Sven Voigtl?nder, Ursula Berger, Oliver Razum
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-403
Abstract: Using 2004 data from the German Socio-Economic Panel Study (SOEP) merged with regional and neighbourhood characteristics, we fitted multilevel linear regression models with subjective physical health, as measured by the SF-12, as the dependent variable. The models include regional and neighbourhood proxies of deprivation (i.e. regional unemployment quota, average purchasing power of the street section) as well as specific neighbourhood exposures (i.e. perceived air pollution). Individual characteristics including socioeconomic status and health behaviour have been controlled for.This study finds a significant association between area deprivation and physical health which is independent of compositional factors and consistent across different spatial scales. Furthermore the association between neighbourhood deprivation and physical health can be partly explained by specific features of the neighbourhood environment. Among these perceived air pollution shows the strongest association with physical health (-2.4 points for very strong and -1.5 points for strong disturbance by air pollution, standard error (SE) = 0.8 and 0.4, respectively). Beta coefficients for perceived air pollution, perceived noise and the perceived distance to recreational resources do not diminish when including individual health behaviour in the models.This study highlights the difference regional and in particular neighbourhood deprivation make to the physical health of individuals in Germany. The results support the argument that specific neighbourhood exposures serve as an intermediary step between deprivation and health. As people with a low socioeconomic status were more likely to be exposed to unfavourable neighbourhood characteristics these conditions plausibly contribute towards generating health inequalities.Research concerned with contextual influences on health, that is the effect of regional and neighbourhood factors on individual health outcomes, and their interplay with compositional
Three-Dimensional Rotational Angiography in Congenital Heart Disease: Estimation of Radiation Exposure  [PDF]
Gloria Reinke, Julia Halbfa?, Sven Dittrich, Rosemarie Banckwitz, Christoph K?hler, Stephan Achenbach, Oliver Rompel, Martin Gl?ckler
Open Journal of Radiology (OJRad) , 2013, DOI: 10.4236/ojrad.2013.33020
Abstract:

Objectives: There is an increasing use of three-dimensional rotational angiography (3D-RA) during catheterization of congenital heart disease. Dose-area-product (DAP) measured by the angiography system and computed-tomography dose index (CTDI) do not appear practical for dose assessment. Hence, we performed real dose measurements in anthropomorphic phantoms. Methods: Three different anthropomorphic phantoms (10 kg, 19 kg and 73 kg bodyweight) equipped with thermoluminescent dosimeters (TLD) were used. We used a typical standard diagnostic program and a low-dose program. The effective dose (ED) was calculated according to the International Commission on Radiological Protection (ICRP) 103. The 3D distribution of radiation in the body was assessed. Results: ED for the male 10 kg phantom was 0.192 mSv in the diagnostic program and 0.050 mSv (male) in the low-dose program. The 19 kg phantom received an ED of 0.205 mSv (male) in the diagnostic program. In the low-dose program the ED reached 0.058 mSv (male). The male adult 73 kg phantom was exposed with an ED of 0.730 mSv in the diagnostic program and 0.282 mSv in the low-dose program. ED for the female phantoms was slightly higher for both acquisition-programs. Dose distribution was inhomogeneous with a dose maximum in the esophageal region behind the heart, whereas in the brain, intestine and gonads we found nearly no radiation. Conclusions: 3D-RA imaging in the interventional catheter laboratory is possible with an effective dose lower than 1 mSv. With its potential to reduce fluoroscopic time and the number of control angiographies in catheterization and intervention in complex anatomy, it can decrease the radiation dose.

Optic Flow Stimuli in and Near the Visual Field Centre: A Group fMRI Study of Motion Sensitive Regions
Sabine Ohlendorf, Andreas Sprenger, Oliver Speck, Sven Haller, Hubert Kimmig
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0004043
Abstract: Motion stimuli in one visual hemifield activate human primary visual areas of the contralateral side, but suppress activity of the corresponding ipsilateral regions. While hemifield motion is rare in everyday life, motion in both hemifields occurs regularly whenever we move. Consequently, during motion primary visual regions should simultaneously receive excitatory and inhibitory inputs. A comparison of primary and higher visual cortex activations induced by bilateral and unilateral motion stimuli is missing up to now. Many motion studies focused on the MT+ complex in the parieto-occipito-temporal cortex. In single human subjects MT+ has been subdivided in area MT, which was activated by motion stimuli in the contralateral visual field, and area MST, which responded to motion in both the contra- and ipsilateral field. In this study we investigated the cortical activation when excitatory and inhibitory inputs interfere with each other in primary visual regions and we present for the first time group results of the MT+ subregions, allowing for comparisons with the group results of other motion processing studies. Using functional magnetic resonance imaging (fMRI), we investigated whole brain activations in a large group of healthy humans by applying optic flow stimuli in and near the visual field centre and performed a second level analysis. Primary visual areas were activated exclusively by motion in the contralateral field but to our surprise not by central flow fields. Inhibitory inputs to primary visual regions appear to cancel simultaneously occurring excitatory inputs during central flow field stimulation. Within MT+ we identified two subregions. Putative area MST (pMST) was activated by ipsi- and contralateral stimulation and located in the anterior part of MT+. The second subregion was located in the more posterior part of MT+ (putative area MT, pMT).
The repertoire of equine intestinal α-defensins
Oliver Bruhn, Sven Paul, Jens Tetens, Georg Thaller
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-631
Abstract: Thirty-eight equine intestinal α-defensin transcripts were determined. After translation it became evident that at least 20 of them may code for functional peptides. Ten transcripts lacked matching genomic sequences and for 14 α-defensin genes apparently present in the genome no appropriate transcript could be verified. In other cases the same genomic exons were found in different transcripts.The large repertoire of equine α-defensins found in this study points to a particular importance of these peptides regarding animal health and protection from infectious diseases. Moreover, these findings make the horse an excellent species to study biological properties of α-defensins. Interestingly, the peptides were not found in other species of the Laurasiatheria to date. Comparison of the obtained transcripts with the genomic sequences in the current assembly of the horse (EquCab2.0) indicates that it is yet not complete and/or to some extent falsely assembled.Antimicrobial peptides are effector molecules of the innate immune system which provides the first line of defense against a wide variety of microbes [1]. These peptides act as endogenous antibiotics protecting the organism against infections with pathogenic microorganisms [2]. Antimicrobial peptides are synthesised by circulating phagocytic cells, leucocytes and epithelial cells of mucosal tissues. Defensins are an important class of antimicrobial peptides which can be found in plants [3], invertebrates [4] and vertebrates [5]. Defensins are cationic and cysteine-rich peptides with a molecular structure consisting of three antiparallel β-sheets [2]. They contain six highly conserved cysteine residues forming characteristic intramolecular disulfide bonds. Mammalian defensins are classified into three distinct sub-families due to the disulfide array: α-, β- und θ-defensins [6]. The peptides exhibit a direct antimicrobial activity against a broad spectrum of microorganisms including Gram-negative and Gram-positive bact
Lung dendritic cells facilitate extrapulmonary bacterial dissemination during pneumococcal pneumonia
Alva Rosendahl,Simone Bergmann,Sven Hammerschmidt,Oliver Goldmann,Eva Medina
Frontiers in Cellular and Infection Microbiology , 2013, DOI: 10.3389/fcimb.2013.00021
Abstract: Streptococcus pneumoniae is a leading cause of bacterial pneumonia worldwide. Given the critical role of dendritic cells (DCs) in regulating and modulating the immune response to pathogens, we investigated here the role of DCs in S. pneumoniae lung infections. Using a well-established transgenic mouse line which allows the conditional transient depletion of DCs, we showed that ablation of DCs resulted in enhanced resistance to intranasal challenge with S. pneumoniae. DCs-depleted mice exhibited delayed bacterial systemic dissemination, significantly reduced bacterial loads in the infected organs and lower levels of serum inflammatory mediators than non-depleted animals. The increased resistance of DCs-depleted mice to S. pneumoniae was associated with a better capacity to restrict pneumococci extrapulmonary dissemination. Furthermore, we demonstrated that S. pneumoniae disseminated from the lungs into the regional lymph nodes in a cell-independent manner and that this direct way of dissemination was much more efficient in the presence of DCs. We also provide evidence that S. pneumoniae induces expression and activation of matrix metalloproteinase-9 (MMP-9) in cultured bone marrow-derived DCs. MMP-9 is a protease involved in the breakdown of extracellular matrix proteins and is critical for DC trafficking across extracellular matrix and basement membranes during the migration from the periphery to the lymph nodes. MMP-9 was also significantly up-regulated in the lungs of mice after intranasal infection with S. pneumoniae. Notably, the expression levels of MMP-9 in the infected lungs were significantly decreased after depletion of DCs suggesting the involvement of DCs in MMP-9 production during pneumococcal pneumonia. Thus, we propose that S. pneumoniae can exploit the DC-derived proteolysis to open tissue barriers thereby facilitating its own dissemination from the local site of infection.
Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations
Fabian Gottwald,Sven Karsten,Sergei D. Ivanov,Oliver Kühn
Physics , 2015, DOI: 10.1063/1.4922941
Abstract: Fundamental understanding of complex dynamics in many-particle systems on the atomistic level is of utmost importance. Often the systems of interest are of macroscopic size but can be partitioned into few important degrees of freedom which are treated most accurately and others which constitute a thermal bath. Particular attention in this respect attracts the linear generalized Langevin equation (GLE), which can be rigorously derived by means of a linear projection (LP) technique. Within this framework a complicated interaction with the bath can be reduced to a single memory kernel. This memory kernel in turn is parametrized for a particular system studied, usually by means of time-domain methods based on explicit molecular dynamics data. Here we discuss that this task is most naturally achieved in frequency domain and develop a Fourier-based parametrization method that outperforms its time-domain analogues. Very surprisingly, the widely used rigid bond method turns out to be inappropriate in general. Importantly, we show that the rigid bond approach leads to a systematic underestimation of relaxation times, unless the system under study consists of a harmonic bath bi-linearly coupled to the relevant degrees of freedom.
Local Delivery of Nimodipine by Prolonged-Release Microparticles—Feasibility, Effectiveness and Dose-Finding in Experimental Subarachnoid Hemorrhage
Daniel H?nggi, Jason Perrin, Sven Eicker, Kerim Beseoglu, Nima Etminan, Marcel Alexander Kamp, Hi-Jae Heiroth, Nadia Bege, Stephan Macht, Katrin Frauenknecht, Clemens Sommer, Thomas Kissel, Hans-Jakob Steiger
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042597
Abstract: Background and Purpose To investigate the effect of locally applied nimodipine prolonged-release microparticles on angiographic vasospasm and secondary brain injury after experimental subarachnoid hemorrhage (SAH). Methods 70 male Wistar rats were categorized into three groups: 1) sham operated animals (control), 2) animals with SAH only (control) and the 3) treatment group. SAH was induced using the double hemorrhage model. The treatment group received different concentrations (20%, 30% or 40%) of nimodipine microparticles. Angiographic vasospasm was assessed 5 days later using digital subtraction angiography (DSA). Histological analysis of frozen sections was performed using H&E-staining as well as Iba1 and MAP2 immunohistochemistry. Results DSA images were sufficient for assessment in 42 animals. Severe angiographic vasospasm was present in group 2 (SAH only), as compared to the sham operated group (p<0.001). Only animals within group 3 and the highest nimodipine microparticles concentration (40%) as well as group 1 (sham) demonstrated the largest intracranial artery diameters. Variation in vessel calibers, however, did not result in differences in Iba-1 or MAP2 expression, i.e. in histological findings for secondary brain injury. Conclusions Local delivery of high-dose nimodipine prolonged-release microparticles at high concentration resulted in significant reduction in angiographic vasospasm after experimental SAH and with no histological signs for matrix toxicity.
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