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Search Results: 1 - 10 of 1070 matches for " Ulrike Erben "
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Combined Pulse Electroporation – A Novel Strategy for Highly Efficient Transfection of Human and Mouse Cells
Thorsten Stroh,Ulrike Erben,Anja A. Kühl,Martin Zeitz,Britta Siegmund
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009488
Abstract: The type of a nucleic acid and the type of the cell to be transfected generally affect the efficiency of electroporation, the versatile method of choice for gene regulation studies or for recombinant protein expression. We here present a combined square pulse electroporation strategy to reproducibly and efficiently transfect eukaryotic cells. Cells suspended in a universal buffer system received an initial high voltage pulse that was continuously combined with a subsequent low voltage pulse with independently defined electric parameters of the effective field and the duration of each pulse. At comparable viable cell recoveries and transfection efficiencies of up to 95% of all cells, a wide variety of cells especially profited from this combined pulse strategy by high protein expression levels of individual cells after transfection. Long-term silencing of gene expression by transfected small interfering RNA was most likely due to the uptake of large nucleic acid amounts as shown by direct detection of fluorochromated small interfering RNA. The highly efficient combined pulse electroporation strategy enables for external regulation of the number of naked nucleic acid molecules taken up and can be easily adapted for cells considered difficult to transfect.
Hydroxyproline-containing collagen analogs trigger the release and activation of collagen-sequestered proMMP-2 by competition with prodomain-derived peptide P33-42
Martin Ruehl, Marion Muche, Christian Freise, Ulrike Erben, Ulf Neumann, Detlef Schuppan, Yury Popov, Walburga Dieterich, Martin Zeitz, Richard W Farndale, Rajan Somasundaram
Fibrogenesis & Tissue Repair , 2011, DOI: 10.1186/1755-1536-4-1
Abstract: In situ zymography and immunohistology showed association of enzymatically inactive prodomain-containing proMMP-2 and proMMP-9 but not of their activated forms to fibrillar collagen structures, which are not substrates of these gelatinases. In solid-phase binding studies with human collagens and collagen fragments, up to 45% of [125I]-labeled proMMP-2 and proMMP-9 but not of active (act)MMP-2 and actMMP-9 were retained by natural collagenous molecules and by synthetic analogs containing repeated Gly-Pro-Hyp triplets (GPO). Surface plasmon resonance yielded binding constants for the interaction of collagen type I (CI) with proMMP-2 and proMMP-9 in a nanomolar range. Values for actMMP-2 and actMMP-9 were 30-40 times higher. Tenfold molar excesses of (GPO)10 reduced the interaction of CI with pro- and actMMP-2 by 22- or 380-fold and resulted in prodomain release accompanied by high enzymatic activation and activity. Pointing to gelatine substrate displacement, higher (GPO)10 concentrations blocked the enzymatic activity. The MMP-2 prodomain-derived collagen-binding domain peptide (P33-42) binds to the collagen-binding domain of MMP-2, thereby preserving enzymatic inactivity. Synthetic P33-42 peptide competed with proMMP-2 binding to CI and prevented (GPO)10-mediated proMMP-2 activation. In contrast to (GPO)10, P33-42 did not activate proMMP-2, making triple helical and hydroxyproline-containing (GPO)10 unique in modulating gelatinase availability and activity.These findings suggest novel strategies using collagen analogs for the resolution of liver fibrosis via fibrotic matrix-sequestered gelatinases.Matrix metalloproteinases (MMPs) form a large family of zinc-dependent metalloendopeptidases that degrade extracellular matrix (ECM) molecules, including various collagens, gelatine, elastin, fibronectin and aggrecan [1]. The diversity of MMP-binding partners and of MMP substrates suggests a central role for MMPs in the "protease web" beyond their proteolytic activity. MMP
A hepatoprotective Lindera obtusiloba extract suppresses growth and attenuates insulin like growth factor-1 receptor signaling and NF-kappaB activity in human liver cancer cell lines
Christian Freise, Martin Ruehl, Ulrike Erben, Ulf Neumann, Daniel Seehofer, Ki Kim, Wolfram Trowitzsch-Kienast, Thorsten Stroh, Martin Zeitz, Rajan Somasundaram
BMC Complementary and Alternative Medicine , 2011, DOI: 10.1186/1472-6882-11-39
Abstract: Four human HCC cell lines representing diverse stages of differentiation were treated with L.obtusiloba extract, standardized according to its known suppressive effects on proliferation and TGF-β-expression. Beside measurement of proliferation, invasion and apoptosis, effects on signal transduction and NF-κB-activity were determined.L.obtusiloba extract inhibited proliferation and induced apoptosis in all HCC cell lines and provoked a reduced basal and IGF-1-induced activation of the IGF-1R signaling cascade and a reduced transcriptional NF-κB-activity, particularly in the poorly differentiated SK-Hep1 cells. Pointing to anti-angiogenic effects, L.obtusiloba extract attenuated the basal and IGF-1-induced expression of hypoxia inducible factor-1α, vascular endothelial growth factor, peroxisome proliferator-activated receptor-γ, cyclooxygenase-2 and inducible nitric oxide synthase.The traditional application of the extract is confirmed by our experimental data. Due to its potential to inhibit critical receptor tyrosine kinases involved in HCC progression via the IGF-1 signaling pathway and NF-κB, the standardized L.obtusiloba extract should be further analysed for its active compounds and explored as (complementary) treatment option for HCC.Hepatocellular carcinoma (HCC) results from chronic liver disease and is the most common malignancy of the liver [1]. Chronic Hepatitis B or C leading to liver cirrhosis are major risk factors for the development of HCC [2]. Even in developing countries less than 40% of patients have a chance for cure when the tumor is diagnosed. In more advanced stages there are only reduced therapeutic options, since e.g. the use of more aggressive chemotherapeutic approaches is often limited by significant liver dysfunction/cirrhosis. Thus, the median survival in advanced HCC without therapy ranges from 4.2 to 7.9 months or even less [3,4]. Small molecules, targeting tumor angiogenesis, apoptosis or specific signal transduction pathways, have ga
Diagnosis of Rabies via RT-PCR on Skin Samples of Wild and Domestic Animals  [PDF]
Ulrike Zieger
Open Journal of Veterinary Medicine (OJVM) , 2015, DOI: 10.4236/ojvm.2015.59026
Abstract: In developing countries, brain tissues from rabies suspect animals are not always available for diagnosis for a variety of reasons, such as lack of transport to submit a carcass or the difficulty of removing an animal’s head or brain under field conditions. To enable diagnosis in such cases, there is a need for a reliable method, using an alternative non-neural tissue, which can be removed and submitted to the diagnostic laboratory without special training or equipment. In human medicine, skin is used successfully for the detection of rabies virus antigen using RT-PCR technology. Little work has been done in animals using RT-PCR on skin or extracted hair follicles. The current study was conducted in Grenada on skin from 36 wild and domestic animals, in which rabies virus infection had been confirmed in brain tissue via the direct fluorescent antibody (DFA) test, and in 31 negative control animals. RT-PCR on skin yielded a sensitivity of 97.2% (35/36) and a specificity of 100% (31/31). It is concluded that the examination of skin samples via RT-PCR provides a valuable diagnostic alternative in those cases where brain tissue is not readily available.
The CAF1-NOT complex of trypanosomes
Esteban Erben,Christine Clayton
Frontiers in Genetics , 2014, DOI: 10.3389/fgene.2013.00299
Abstract: In African trypanosomes, there is no control of transcription initiation by RNA polymerase II at the level of individual protein-coding genes. Transcription is polycistronic, and individual mRNAs are excised by trans-splicing and polyadenylation. As a consequence, trypanosomes are uniquely reliant on post-transcriptional mechanisms for control of gene expression. Rates of mRNA decay vary over up to two orders of magnitude, making these organisms an excellent model system for the study of mRNA degradation processes. The trypanosome CAF1-NOT complex is simpler than that of other organisms, with no CCR4 or NOT4 homolog: it consists of CAF1, NOT1, NOT2, NOT5 NOT9, NOT10, and NOT11. It is important for the initiation of degradation of most, although not all, mRNAs. There is no homolog of NOT4, and Tho and TREX complexes are absent. Functions of the trypanosome NOT complex are therefore likely to be restricted mainly to deadenylation. Mechanisms that cause the NOT complex to deadenylate some mRNAs faster than others must exist, but have not yet been described.
The Discursive Constitution of Ocean Sustainability  [PDF]
Ulrike Kronfeld-Goharani
Advances in Applied Sociology (AASoci) , 2015, DOI: 10.4236/aasoci.2015.512030
Abstract: As part of a search for political responses to protect and conserve marine ecosystems, this study explores the discourse on ocean affairs with a special emphasis on the articulation of the concept of sustainability. Drawing on the discourse theory of Ernesto Laclau and Chantal Mouffe, it is argued that post structuralism offers important insights on the construction of the discourse on maritime-related affairs. The analysis shows that the discourse on ocean affairs is closely tied to the empty signifier “management”, while the analysis of the empty signifier “sustainability” confirms the traditional three dimensional structure comprising economic, social and environmental dimensions, supplemented by an institutional one. The article shows that the use of such signifiers is necessary to define sustainability in all its complexity. In this context, it is argued that Laclau and Mouffe’s discourse theory provides an approach to grasp the ambiguity of the concept of sustainability. It helps to explain the practice of institutions in rephrasing existing objectives and activities in compliance with sustainability without really changing their business as usual approach. The paper concludes with an estimation of how useful it is to adhere to sustainability in ocean affairs especially in view of the complexity, uncertainty and continuous change of marine ecosystems.
Kompetenzorientierung im Fremdsprachenunterricht: was heiβt das eigentlich?
Arras, Ulrike;
Pandaemonium Germanicum , 2009, DOI: 10.1590/S1982-88372009000100011
Abstract: in recent years, the teaching of foreign languages in schools, universities and other institutions involved with language learning has faced several changes and new orientations. the main reason for these changes certainly is the common european framework of languages, published in 2001 by the european council. in germany we additionally develop new educational standards, considering as representative examples english and french as first foreign languages taught in our school system (kultusministerkonferenz (ed.) 2004; tesch et al. (eds.) 2008). normally, such changes in educational systems lead to uncertainty and confusion, a context this article intends to clarify. are we now asked to design our classes, our material and our curricula in completely new modes? what consequences do teachers as well as learners face up to following these new approaches in teaching and learning? what does competence orientation mean exactly? and which chances does it offer?
Die Bibliothek der Medizinischen Universit t Graz: Visionen – Konzepte – Fakten / The library of the Medical University of Graz: visions – concepts – facts
Kortschak, Ulrike
GMS Medizin-Bibliothek-Information , 2009,
Abstract: This article gives short overview of the history and the philosophy of the Library of the Medical University of Graz. The library was founded in 2004 and developed in the last five years modern standards.
Performative Forschung in der Kunstp dagogik am Beispiel von Szenen aus dem Seminar "Erforschen performativer Rituale im Stadtraum" Performative Research in Art Education: Scenes from the Seminar "Exploring Performative Rituals in City Space" Investigación performativa en la educación artística: escenas del seminario Análisis de los rituales performativos en el espacio de la ciudad
Ulrike Stutz
Forum : Qualitative Social Research , 2008,
Abstract: In meinem Beitrag fundiere ich einen performativen Ansatz kunstp dagogischer Forschung und wende diesen auf drei Beispiele aus einem Performance-Seminar mit Studierenden an. Hierbei unterziehe ich Video-Dokumentationen, die innerhalb von performativen Aktionen entstanden, einer inszenierenden Analyse mit medialen Verfahren. Mein Untersuchungsinteresse richtet sich dabei auf die Reaktionen von Passant/innen als expanded audience dieser Aktionen einer site specific art und somit auf die Ver nderungen der Qualit t des sozialen Raums, die durch die inszenierenden Interventionen stattfanden. Der Beitrag ist in der Verwendung von Texten, Videos und Animationen als multimediales Dokument aufbereitet. Durch die parallele Pr sentation unterschiedlicher Medienformate werden differenzsetzende und aktivierende Lesarten produziert. URN: urn:nbn:de:0114-fqs0802514 In my contribution, I lay the foundations for a performative approach to art education research and then apply it to three examples from a performance seminar conducted with university students. In the process, I subject video documentaries produced during performative exploration of everyday rituals in public space, to a fresh performative analysis using media techniques. My research interest targets the reactions of passers-by as an expanded audience, i.e., it targets the qualitative changes of social space brought about by these actions of site specific art. The contribution is presented as a multimedia document with videos and animations. The parallel presentation of different media formats produces differentiating and activating readings. URN: urn:nbn:de:0114-fqs0802514 En mi contribución, pongo los cimientos de un enfoque performativo para la investigación en la educación artística y lo aplico luego a tres ejemplos de un seminario de performance dirigido a estudiantes de la universidad. En el proceso, someto los videos de documentales producidos durante la exploración performativa de los rituales diarios en el espacio público a un análisis performativo fresco que usa medios técnicos. Mi interés de investigación se centra en las reacciones de transeúntes como una amplia audiencia, es decir, se centra en los cambios cualitativos del espacio social provocados por estas acciones del arte de lugar específico. La contribución es presentada como un documento multimedia con videos y animaciones. La presentación paralela con formatos de diferentes medios causa lecturas diferenciadoras y activadoras. URN: urn:nbn:de:0114-fqs0802514
Spuren von Traumatisierungen in narrativen Interviews Traces of Traumatizations in Narrative Interviews Rastros de traumatización en entrevistas narrativas
Ulrike Loch
Forum : Qualitative Social Research , 2008,
Abstract: Traumatische Kindheitserfahrungen k nnen zur Ausbildung von Dissoziation als Reparaturmechanismus und infolgedessen zu fragmentierten Erinnerungen führen. In narrativen Interviews zeigen sich diese Fragmentierungen als Spuren im Ausdrucksfeld der Sprache. In diesem Beitrag wird anhand von Fallbeispielen aufgezeigt, wie sich Dissoziationen als Folge von Traumatisierungen in der Vergangenheit wie auch in der Gegenwart sprachlich ausdrücken k nnen und welche unterstützenden M glichkeiten Interviewer/innen in Forschungssituationen haben. Denn erst das Erkennen von traumatisch bedingten Inkonsistenzen erm glicht das Verstehen von Lebensgeschichten traumatisierter Menschen jenseits von kollektiv wirksamen Tabuisierungen. Auf diese Weise vermeiden Forscher/innen die Reproduktion von gesellschaftlich relevanten Schweigegeboten bzw. Verleugnungsprozessen im wissenschaftlichen Kontext. URN: urn:nbn:de:0114-fqs0801544 Traumatic childhood experiences often lead to the development of dissociation as a defense mechanism, and subsequently to fragmented memories. In narrative interviews this fragmentation is traced in the expressive field of language. In this article a range of case studies are used to illustrate how dissociations, resulting from traumatic experiences in the past as well as the present, may express themselves and how we, as interviewers, can give support to the client in interview situations. Only by understanding the inconsistencies caused by these traumatic experiences, interviewees are able to tell their life histories beyond the collectively effective taboos. By becoming aware of these mechanisms, the researcher can steer clear of reproducing the socially relevant silencing effects, i.e. denial processes, within the context of social scientific research. URN: urn:nbn:de:0114-fqs0801544 Experiencias infantiles traumáticas a menudo conducen al desarrollo de la disociación como un mecanismo de defensa y, por consiguiente, a memorias fragmentadas. En las entrevistas narrativas esta fragmentación se localiza en los campos expresivos del lenguaje. En este artículo un conjunto de estudios de caso ilustran como las disociaciones, resultantes de experiencias traumáticas tanto del pasado como del presente, pueden expresarse y como nosotros, en tanto entrevistadores, podemos brindar apoyo a los clientes en las situaciones de entrevista. Solamente mediante la comprensión de las inconsistencias causadas por esas experiencias traumáticas, los entrevistados son capaces de decir sus historias de vida más allá de los tabúes colectivamente efectivos. Al ser concient
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