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Search Results: 1 - 10 of 1430 matches for " Ulf Nestler "
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MALDI-TOF Mass Spectrometric Analysis of Brain Tumor Cyst Fluid Reveals a Protein Peak Corresponding to ApoC1 and LuzP6  [PDF]
Mathias Groll, Jochen Frenzel, Matthias Krause, Anne Sch?nzer, Wolf Müller, Klaus Eschrich, Ulf Nestler
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.83021
Abstract: Objectives: SELDI-TOF and MALDI-TOF mass spectrometry (MS) are laser desorption technologies that allow for proteomic examination of molecular masses in small amounts of samples. In a precedent study, the feasibility of SELDI-TOF MS assessment of proteins in cerebrospinal fluid and tumor cyst fluid had been shown. In the present study, we analyzed whether MALDI-TOF MS examination of these fluids leads to comparable results. Methods: During neurosurgical intervention, cyst fluids from 24 glioblastomas and 15 metastases were collected. As control, cerebrospinal fluid samples from 23 patients were obtained. The samples were prepared using a protocol optimized for MALDI-TOF MS. Mass spectra were recorded and peaks were extracted, characterized by masses and relative intensities. These peaks were analyzed for statistically significant differences between the diagnosis groups and compared to SELDI-TOF MS data. Results: 41 protein peaks known from the SELDI-TOF MS analysis could be confirmed by MALDI-TOF MS, and the cellular expression of the proteins LuzP6 and ApoC1, corresponding to the protein peaks 6433 and 6632, was shown immunohistochemically in glioblas-toma tissue. The MALDI-TOF spectrometry extends the range of analysis down to 1.4 kDa, whereas the upper detection limit lies below 23 kDa. Discussion: The presented proteomic approach yields an inventory of protein masses, found in the tumor cyst at the time of puncture. It does not reveal pathophysiologic, metabolic or secretory pathways that lead to the presence of proteins in the cyst. These have to be assessed immunohistochemically or on mRNA level in the surrounding tumor cells. Conclusion: MALDI-TOF MS of tumor cyst fluid discloses protein sizes, overexpressed or lost in tumor tissue. A thorough proteomic work-up is needed to identify the underlying proteins and metabolic pathways.
Sinogenic Subdural Empyema in a Ten-Year-Old Boy with Sickle Cell Anemia  [PDF]
Ulf Nestler, Daniel Memia-Zolo, Nidal Salloum, Mehdi Mejdoubi, Fran?ois Lengelle, Raoul Santiago, William Cécile, Remus Stegaru, Norbert Manzo
Open Journal of Modern Neurosurgery (OJMN) , 2013, DOI: 10.4236/ojmn.2013.34012
Abstract: Objective: Sinogenic subdural empyema remains a neurosurgical emergency, even in the antibiotic era. Sickle cell disease is one of the most frequent hereditary diseases, with an incidence of around 4 in 1000 newborns, which necessitates special considerations before a neurosurgical intervention. Case Description: The case of a 10-year-old boy with sickle cell disease type HbSC is reported, who presented with meningitis about ten days after a nasal sinusitis. CT and MRI showed subdural empyema and immediate intravenous antibiotic treatment was started. The patient received partial exchange transfusion. Craniotomy allowed evacuation of empyema and repairment of a frontobasal dural defect. Endoscopic evacuation of the paranasal sinuses was done in the same anesthesia. After initial good recovery, the patient developed right sided paresis with epileptic seizures a few days later. CT scan revealed three distant empyema recurrencies which were evacuated in a second neurosurgical intervention. The child recovered without neurologic deficit, and control MRI examinations three and twelve months after surgery found frontal and parietal dural thickening as sequelae. Conclusion: Urgent neurosurgical interventions in the presence of sickle cell anemia require special anesthesiologic preparations. An immediate, multidisciplinary approach can lead to a good outcome in these life-threatening situations.
Surgical Treatment for Neonatal Hydrocephalus: Catheter-Based Cerebrospinal Fluid Diversion or Endoscopic Intervention?  [PDF]
Matthias Krause, Christos P. Panteliadis, Christian Hagel, Franz W. Hirsch, Ulrich H. Thome, Jürgen Meixensberger, Ulf Nestler
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.81002
Abstract: Neonatal hydrocephalus can arise from a multitude of disturbances, among them congenital aqueductal stenosis, myelomeningocele or posthemorrhagic complications in preterm infants. Diagnostic work-up comprises transfontanellar ultrasonography, T2 weighted MRI and clinical assessment for rare inherited syndromes. Classification of hydrocephalus and treatment guidelines is based on detailed consensus statements. The recent evidence favors catheter-based cerebrospinal fluid diversion in children below 6 months, but emerging techniques such as neuroendoscopic lavage carry the potential to lower shunt insertion rates. More long-term study results will be needed to allow for individualized, multidisciplinary decision making. This article gives an overview regarding contemporary pathophysiological concepts, the latest consensus statements and most recent technical developments.
OPTIMAL THICKNESS OF A CYLINDRICAL SHELL - AN OPTIMAL CONTROL PROBLEM IN LINEAR ELASTICITY THEORY
Peter Nestler
Mathematics and its Applications : Annals of the Academy of Romanian Scientists , 2013,
Abstract: In this paper we discuss optimization problems for cylindrical tubeswhich are loaded by an applied force. This is a problem of optimal control in linear elasticity theory (shape optimization). We are looking for an optimal thickness minimizing the deflection (deformation) of the tube under the influence of an external force. From basic equations of mechanics, we derive the equation of deformation. We apply the displacement approach from shell theory and make use of the hypotheses of Mindlin and Reissner. A corresponding optimal control problem is formulated and first order necessary conditions for the optimal solution (optimal thickness) are derived. We present numerical examples which were solved by the finite element method.
Julia Diek mper: Reproduziertes Leben. Biomacht in Zeiten der Pr implantationsdiagnostik. Bielefeld: transcript Verlag 2011.
Sebastian Nestler
querelles-net , 2012,
Abstract: Julia Diek mper zeigt mit ihrer Studie, wie die Pr implantationsdiagnostik (PID) zum umk mpften Gegenstand medialer Aushandlungen geworden ist. Anhand eines Vergleichs der Diskussion in deutschen und franz sischen Printmedien wird dargelegt, wie im Sinne Foucaults eine diskursive Auseinandersetzung um die PID stattfindet. Die Arbeit besticht durch ihren klar strukturierten empirischen Teil, der eine geologische Karte des PID-Diskurses zeichnet. Damit wird auch die aktuelle Relevanz des Begriffs der Bio-Macht unterstrichen. Ein Schritt in Richtung einer Genealogie bleibt aber aus. So verbleibt die Studie eher auf der deskriptiven Ebene, das von Foucault stets geforderte Infragestellen von Machtbeziehungen wird nicht eingel st, aber fundiertes Material für ein solches geliefert. With her study, Julia Diek mper shows how preimplantation genetic diagnosis (PGD) has become a fiercely disputed topic of medial negotiations. Based on a comparison of the discussion in German and French print media, she illustrates (in Foucauldian terms) how a discoursive controversy on PGD happens. The study impresses with its clearly structured empirical section, which draws a geological map of the PGD-discourse. This also underlines the current pertinence of the term biopower. However, the study fails to offer a step towards a genealogy. Thus, the study remains on the descriptive level; it does not implement the questioning of power relations, always postulated by Foucault, but it offers profound material for such questioning.
Phase-field simulations of solidification in binary and ternary systems using a finite element method
Denis Danilov,Britta Nestler
Physics , 2004, DOI: 10.1016/j.jcrysgro.2004.10.139
Abstract: We present adaptive finite element simulations of dendritic and eutectic solidification in binary and ternary alloys. The computations are based on a recently formulated phase-field model that is especially appropriate for modelling non-isothermal solidification in multicomponent multiphase systems. In this approach, a set of governing equations for the phase-field variables, for the concentrations of the alloy components and for the temperature has to be solved numerically, ensuring local entropy production and the conservation of mass and inner energy. To efficiently perform numerical simulations, we developed a numerical scheme to solve the governing equations using a finite element method on an adaptive non-uniform mesh with highest resolution in the regions of the phase boundaries. Simulation results of the solidification in ternary Ni$_{60}$Cu$_{40-x}$Cr$_{x}$ alloys are presented investigating the influence of the alloy composition on the growth morphology and on the growth velocity. A morphology diagram is obtained that shows a transition from a dendritic to a globular structure with increasing Cr concentrations. Furthermore, we comment on 2D and 3D simulations of binary eutectic phase transformations. Regular oscillatory growth structures are observed combined with a topological change of the matrix phase in 3D. An outlook for the application of our methods to describe AlCu eutectics is given.
Dendritic to globular morphology transition in ternary alloy solidification
Denis Danilov,Britta Nestler
Physics , 2005, DOI: 10.1103/PhysRevLett.93.215501
Abstract: The evolution of solidification microstructures in ternary metallic alloys is investigated by adaptive finite element simulations of a general multicomponent phase-field model. A morphological transition from dendritic to globular growth is found by varying the alloy composition at a fixed undercooling. The dependence of the growth velocity and of the impurity segregation in the solid phase on the composition is analyzed and indicates a smooth type of transition between the dendritic and globular growth structures.
Phase-field modelling of solute trapping during rapid solidification of a Si-As alloy
Denis Danilov,Britta Nestler
Physics , 2006, DOI: 10.1016/j.actamat.2006.05.045
Abstract: The effect of nonequilibrium solute trapping by a growing solid under rapid solidification conditions is studied using a phase-field model. Considering a continuous steady-state concentration profile across the diffuse solid-liquid interface, a new definition of the nonequilibrium partition coefficient in the phase-field context is introduced. This definition leads, in particular for high growth velocities, to a better description of the available experimental data in comparison with other diffuse interface and sharp-interface predictions.
The Striatal Balancing Act in Drug Addiction: Distinct Roles of Direct and Indirect Pathway Medium Spiny Neurons
Mary Kay Lobo,Eric J. Nestler
Frontiers in Neuroanatomy , 2011, DOI: 10.3389/fnana.2011.00041
Abstract: The striatum plays a key role in mediating the acute and chronic effects of addictive drugs, with drugs of abuse causing long-lasting molecular and cellular alterations in both dorsal striatum and nucleus accumbens (ventral striatum). Despite the wealth of research on the biological actions of abused drugs in striatum, until recently, the distinct roles of the striatum’s two major subtypes of medium spiny neurons (MSNs) in drug addiction remained elusive. Recent advances in cell-type-specific technologies, including fluorescent reporter mice, transgenic, or knockout mice, and viral-mediated gene transfer, have advanced the field toward a more comprehensive understanding of the two MSN subtypes in the long-term actions of drugs of abuse. Here we review progress in defining the distinct molecular and functional contributions of the two MSN subtypes in mediating addiction.
Three-dimensional phase-field study of crack-seal microstructures - Insights from innovative post-processing techniques
Kumar Ankit,Michael Selzer,Britta Nestler
Physics , 2013, DOI: 10.5194/gmdd-7-631-2014
Abstract: Numerical simulations of vein evolution contribute to a better understanding of processes involved in their formation and possess the potential to provide invaluable insights into the rock deformation history and fluid flow pathways. The primary aim of the present article is to investigate the influence of a realistic boundary condition, i.e. an algorithmically generated fractal surface, on the vein evolution in 3-D using a thermodynamically consistent approach, while explaining the benefits of accounting for an extra dimensionality. The 3-D simulation results are supplemented by innovative numerical post-processing and advanced visualization techniques. The new methodologies to measure the tracking efficiency demonstrate the importance of accounting the temporal evolution; no such information is usually accessible in field studies and notoriously difficult to obtain from laboratory experiments as well. The grain growth statistics obtained by numerically post-processing the 3-D computational microstructures explain the pinning mechanism which leads to arrest of grain boundaries/multi-junctions by crack peaks, thereby, enhancing the tracking behavior.
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