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Search Results: 1 - 10 of 54 matches for " Engelbert Knosp "
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Hypothermia in the operating theatre
Andreas Gruber, Wilhelm Behringer, Engelbert Knosp
Critical Care , 2012, DOI: 10.1186/cc11275
Abstract: Cerebral ischaemia results from a reduction or complete loss of cerebral blood flow (CBF) and lack of cerebral oxygenation, followed by depletion of ATP, dysfunction of ATP-dependent membrane pumps and subsequently occurrence of anoxic depolarisation. A large amount of glutamate is released from the intracellular space into the extracellular space, causing excitotoxic injury by stimulating N-methyl-D-aspartate (NMDA) receptors and triggering calcium influx. Increased intracellular calcium levels per se amplify injury by increasing calcium permeability and glutamate release via second messenger mechanisms. These acute cascades lead to necrotic neuronal death by interfering with the mitochondrial respiratory chain. Ischaemia and reperfusion further enhance excitotoxicity by providing oxygen as a substrate for several enzymatic oxidation reactions, thereby generating products of reactive oxygen species in large quantities. These free radicals enhance protein oxidation and lipid membrane disintegration and in conjunction with blood-brain barrier (BBB) disruption further contribute to ischaemic necrosis. Apoptosis also occurs in cerebral ischemia, with antiapoptotic proteins being selectively upregulated in surviving neurons and proapoptotic proteins being highly expressed in dying cells.The first controlled attempts to cool the human brain were undertaken by the neurosurgeon Temple Fay in 1938 [1]. Irrigating the brain directly with ice water and sometimes achieving solid parenchymal freezing, he claimed 'extremely gratifying results' in a paper on 'local and generalized refrigeration of the human brain'. Over time, many mechanisms have been proposed regarding the neuroprotective effect of hypothermia. First, hypothermia results in a temperature-dependent decrease of oxygen and glucose metabolism; that is, a 10°C decrease in temperature reduces ATP consumption and the cerebral metabolic rate (CMR) of oxygen, glucose, and lactate twofold to fourfold [2]. Second, intra-is
5-Aminolevulinic Acid Induced Fluorescence Is a Powerful Intraoperative Marker for Precise Histopathological Grading of Gliomas with Non-Significant Contrast-Enhancement
Georg Widhalm, Barbara Kiesel, Adelheid Woehrer, Tatjana Traub-Weidinger, Matthias Preusser, Christine Marosi, Daniela Prayer, Johannes A. Hainfellner, Engelbert Knosp, Stefan Wolfsberger
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076988
Abstract: Background Intraoperative identification of anaplastic foci in diffusely infiltrating gliomas (DIG) with non-significant contrast-enhancement on MRI is indispensible to avoid histopathological undergrading and subsequent treatment failure. Recently, we found that 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PpIX) fluorescence can visualize areas with increased proliferative and metabolic activity in such gliomas intraoperatively. As treatment of DIG is predominantely based on histopathological World Health Organisation (WHO) parameters, we analyzed whether PpIX fluorescence can detect anaplastic foci according to these criteria. Methods We prospectively included DIG patients with non-significant contrast-enhancement that received 5-ALA prior to resection. Intraoperatively, multiple samples from PpIX positive and negative intratumoral areas were collected using a modified neurosurgical microscope. In all samples, histopathological WHO criteria and proliferation rate were assessed and correlated to the PpIX fluorescence status. Results A total of 215 tumor specimens were collected in 59 patients. Of 26 WHO grade III gliomas, 23 cases (85%) showed focal PpIX fluorescence, whereas 29 (91%) of 33 WHO grade II gliomas were PpIX negative. In intratumoral areas with focal PpIX fluorescence, mitotic rate, cell density, nuclear pleomorphism, and proliferation rate were significantly higher than in non-fluorescing areas. The positive predictive value of focal PpIX fluorescence for WHO grade III histology was 85%. Conclusions Our study indicates that 5-ALA induced PpIX fluorescence is a powerful marker for intraoperative identification of anaplastic foci according to the histopathological WHO criteria in DIG with non-significant contrast-enhancement. Therefore, application of 5-ALA optimizes tissue sampling for precise histopathological diagnosis independent of brain-shift.
Bildanalyse und technologischer Standard - ein kritischer Rückblick auf Multimedia
Engelbert, Arthur
Zeitenblicke , 2003,
Abstract: In dem Beitrag geht es um einen Rückblick auf die Anf nge des manipulierbaren, digitalen Bildes im Kontext der Kunst. An einem Fallbeispiel, dem Johannesaltar des Rogier van der Weyden, erfolgt eine praktische Auseinandersetzung mit den technologisch bedingten Grenzen der Bildanalyse. Dies mündet in eine kritische Bilanz vorfabrizierter Wissensvermittlung und Sichtbarkeitserfahrung nicht nur im Bereich der Kunstgeschichte. Die These lautet von daher ganz allgemein gefasst: Tradierte Bildlichkeit fristet ihr Dasein nicht mehr allein im musealen Raum, sondern ist bereits in einen technologisch bedingten transferiert.
Financialization, income distribution and the crisis
Engelbert Stockhammer
Investigación económica , 2012,
Abstract:
Karotis-Sinus-cavernosus-Fistel
Gruber A,Knosp E
Journal für Neurologie, Neurochirurgie und Psychiatrie , 2013,
Abstract:
Neurochirurgische OP-Indikation bei malignen Mediainfarkten
Gruber A,Knosp E
Journal für Neurologie, Neurochirurgie und Psychiatrie , 2011,
Abstract: Bei Patienten mit malignen Mediainfarkten kann durch dekompressive Hemikraniektomie (DHC) die unter konservativem Management bei 80 % liegende Mortalit t auf 30 % gesenkt werden. überleben und gutes neurologisches Outcome nach Mediainfarkt und DHC sind vor allem dann zu erwarten, wenn jüngere Patienten ( 60 Jahre) früh ( 48 Stunden nach Symptombeginn) zur Operation gelangen. Für 60-j hrige Patienten sowie für den Zeitraum 48 Stunden nach Symptombeginn gibt es derzeit keine sicheren Daten und die Entscheidung über eine m gliche Operation muss einzelfallabh ngig erfolgen. Die diesen überlegungen zugrunde liegenden Metaanalysen weisen methodische Probleme, konkret Post-hoc- Subgruppenanalysen (2009) und eine Modifikation des prim ren Studienendpunkts (2007) auf. Die Grundaussage der Studien und damit die Rationale für DHC bei malignem Mediainfarkt bleiben davon jedoch unberührt.
Custos de Troca em Tecnologia da Informa o: a Proposi o de um Modelo Taxon mico Integrado a partir da Literatura Switching costs in Information Technology: the proposal of an integrated taxonomic model based on literature
Ricardo Engelbert,Alexandre Graeml
Revista Organiza??es em Contexto , 2011,
Abstract: Este artigo tem como objetivo a proposi o de um modelo taxon mico integrado para os custos de troca em tecnologia da informa o (TI). Estes custos desempenham papel decisivo nos processos de mudan a de tecnologia executados pelas organiza es, podendo limitar ou mesmo impedir que ocorram, reduzindo a flexibilidade do negócio para ajustar-se a novas condi es ambientais. Em fun o do aprisionamento a que podem submeter uma organiza o, é importante que se estudem os custos de troca e formas de realizar a sua medi o, de modo a reduzir o seu impacto sobre o processo decisório de ado o de novas tecnologias. Os constru-tos que comp em o modelo abrangente foram obtidos a partir de meticulosa análise da litera-tura das áreas de estratégia, economia, marketing, sistemas de informa o e psicologia. As defini es presentes nos diversos estudos publicados nessas áreas foram analisadas a partir dos níveis da solu o, do fornecedor e dos processos de gest o envolvidos na troca de tecnologias. Uma perspectiva temporal capaz de possibilitar a compreens o de custos que ocorrem em diversos estágios do processo de mudan a também foi incluída no modelo, para contemplar tanto custos prévios quanto custos potenciais, que só se concretizam após a efetiva o da troca de tecnologia. Os custos foram classificados como: custos de sele o, custos de ativa o, custos de constru o, custos formais, custos psicológicos, custos de oportunidade e custos de se voltar à solu o anterior. Ao se adotar uma perspectiva interdisciplinar, ou ao menos ao se dar aten o às contribui es proporcionadas pelas diversas disciplinas, os autores acreditam ter contribuído para a amplia o do entendimento dos pesquisadores em administra o, e mais especificamente de sistemas de informa o, sobre este assunto, t o relevante para a área. O modelo abrangente ora desenvolvido (nenhum outro modelo anterior tinha agregado tantos tipos distintos de custos de troca em uma única representa o) pode também ser útil para profissionais que vivenciem em seu dia-a-dia organizacional a necessidade de tomar decis es em que os custos de troca sejam fatores importantes a considerar. Como as ambi es do modelo s o apenas descritivas dos custos de troca, e considerando que ele se baseou em outros estudos que por sua vez se apoiaram na prática do mercado empresarial e no comportamento humano em processos decisórios, n o há necessidade de valida o empírica para que o modelo possa ser prontamente utilizado. Ainda assim, futuros estudos podem se concentrar em identificar quais desses custos s o predomi nantes em que situa
Gravitation Is Torsion
Engelbert L. Schucking
Physics , 2008,
Abstract: The mantra about gravitation as curvature is a misnomer. The curvature tensor for a standard of rest does not describe acceleration in a gravitational field but the \underline{gradient} of the acceleration (e.g. geodesic deviation). The gravitational field itself (Einstein 1907) is essentially an accelerated reference system. It is characterized by a field of orthonormal four-legs in a Riemann space with Lorentz metric. By viewing vectors at different events having identical leg-components as parallel (teleparallelism) the geometry in a gravitational field defines torsion. This formulation of Einstein's 1907 principle of equivalence uses the same Riemannian metric and the same 1916 field equations for his theory of gravitation and fulfills his vision of General Relativity.
Einstein's Apple and Relativity's Gravitational Field
Engelbert L. Schucking
Physics , 2009,
Abstract: The foundations of Einstein's first (1907) principle of equivalence are explored and their consequences are stated in terms of invariance under generalized Lorentz transformations, first explored by Hessenberg.
Dental gold alloys
Helmut Knosp,Mirza Nawaz,Manfred Stümke
Gold Bulletin , 1981, DOI: 10.1007/BF03214598
Abstract: The special qualities called for in materials for restorative and corrective dental devices have led to the development of a wide variety of dental alloys. Gold alloys, ranging from simple to very complex, are available which satisfy the technical and aesthetic needs of both practitioners and technicians.
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