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Search Results: 1 - 10 of 587 matches for " Dietmar Pum "
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S-Layer Protein Self-Assembly
Dietmar Pum,Jose Luis Toca-Herrera,Uwe B. Sleytr
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14022484
Abstract: Crystalline S(urface)-layers are the most commonly observed cell surface structures in prokaryotic organisms (bacteria and archaea). S-layers are highly porous protein meshworks with unit cell sizes in the range of 3 to 30 nm, and thicknesses of ~10 nm. One of the key features of S-layer proteins is their intrinsic capability to form self-assembled mono- or double layers in solution, and at interfaces. Basic research on S-layer proteins laid foundation to make use of the unique self-assembly properties of native and, in particular, genetically functionalized S-layer protein lattices, in a broad range of applications in the life and non-life sciences. This contribution briefly summarizes the knowledge about structure, genetics, chemistry, morphogenesis, and function of S-layer proteins and pays particular attention to the self-assembly in solution, and at differently functionalized solid supports.
Sensitivity of Aspergillus nidulans to the Cellulose Synthase Inhibitor Dichlobenil: Insights from Wall-Related Genes’ Expression and Ultrastructural Hyphal Morphologies
Gea Guerriero, Lucia Silvestrini, Michael Obersriebnig, Marco Salerno, Dietmar Pum, Joseph Strauss
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0080038
Abstract: The fungal cell wall constitutes an important target for the development of antifungal drugs, because of its central role in morphogenesis, development and determination of fungal-specific molecular features. Fungal walls are characterized by a network of interconnected glycoproteins and polysaccharides, namely α-, β-glucans and chitin. Cell walls promptly and dynamically respond to environmental stimuli by a signaling mechanism, which triggers, among other responses, modulations in wall biosynthetic genes’ expression. Despite the absence of cellulose in the wall of the model filamentous fungus Aspergillus nidulans, we found in this study that fungal growth, spore germination and morphology are affected by the addition of the cellulose synthase inhibitor dichlobenil. Expression analysis of selected genes putatively involved in cell wall biosynthesis, carried out at different time points of drug exposure (i.e. 0, 1, 3, 6 and 24 h), revealed increased expression for the putative mixed linkage β-1,3;1,4 glucan synthase celA together with the β-1,3-glucan synthase fksA and the Rho-related GTPase rhoA. We also compared these data with the response to Congo Red, a known plant/fungal drug affecting both chitin and cellulose biosynthesis. The two drugs exerted different effects at the cell wall level, as shown by gene expression analysis and the ultrastructural features observed through atomic force microscopy and scanning electron microscopy. Although the concentration of dichlobenil required to affect growth of A. nidulans is approximately 10-fold higher than that required to inhibit plant cellulose biosynthesis, our work for the first time demonstrates that a cellulose biosynthesis inhibitor affects fungal growth, changes fungal morphology and expression of genes connected to fungal cell wall biosynthesis.
On the lipid-bacterial protein interaction studied by quartz crystal microbalance with dissipation, transmission electron microscopy and atomic force microscopy
Mihaela Delcea,Susana Moreno-Flores,Dietmar Pum,Uwe Bernd Sleytr,Jose Luis Toca-Herrera
Physics , 2009,
Abstract: The interaction between the bacterial S-protein SbpA on different types of lipid membranes has been studied using atomic force microscopy, transmission electron microscopy, and quartz crystal microbalance with dissipation. On one hand, It has been found that the bacterial forms two dimensional nanocrystals on zwitterionic DOPC bilayers and negatively charged DMPG vesicles adsorbed on mica, on zwitterionic DPPC and charged DPPC/DMPG (1:1) monolayers adsorbed on carbon grids. On the other hand, SbpA protein adsorption took place on zwitterionic DOPC bilayers and DOPC/DOPS (4:1) bilayers, previously adsorbed on silicon supports. SbpA adsorption also took place on DPPC/DOPS (1:1) monolayers adsorbed on carbon grids. Finally, neither SbpA adsorption, nor recrystallization was observed on zwitterionic DMPC vesicles (previously adsorbed on polyelectrolyte multilayers), and on DPPC vesicles supported on silicon.
Identification and characterization of domains responsible for self-assembly and cell wall binding of the surface layer protein of Lactobacillus brevis ATCC 8287
Silja ?vall-J??skel?inen, Ulla Hyn?nen, Nicola Ilk, Dietmar Pum, Uwe B Sleytr, Airi Palva
BMC Microbiology , 2008, DOI: 10.1186/1471-2180-8-165
Abstract: In this work, the self-assembly and cell wall binding domains of SlpA were characterized. The C-terminal self-assembly domain encompassed residues 179–435 of mature SlpA, as demonstrated by the ability of N-terminally truncated recombinant SlpA to form a periodic structure indistinguishable from that formed by full length SlpA. Furthermore, a trypsin degradation analysis indicated the existence of a protease resistant C-terminal domain of 214 amino acids. By producing a set of C-terminally truncated recombinant SlpA (rSlpA) proteins the cell wall binding region was mapped to the N-terminal part of SlpA, where the first 145 amino acids of mature SlpA alone were sufficient for binding to isolated cell wall fragments of L. brevis ATCC 8287. The binding of full length rSlpA to the cell walls was not affected by the treatment of the walls with 5% trichloroacetic acid (TCA), indicating that cell wall structures other than teichoic acids are involved, a feature not shared by the Lactobacillus acidophilus group S-layer proteins characterized so far. Conserved carbohydrate binding motifs were identified in the positively charged N-terminal regions of six Lactobacillus brevis S-layer proteins.This study identifies SlpA as a two-domain protein in which the order of the functional domains is reversed compared to other characterized Lactobacillus S-layer proteins, and emphasizes the diversity of potential cell wall receptors despite similar carbohydrate binding sequence motifs in Lactobacillus S-layer proteins.Surface layers (S-layers) are cell envelope structures ubiquitously found in Gram-positive and Gram-negative bacterial species as well as in Archaea. They are composed of numerous identical (glyco)protein subunits, 40–200 kDa in molecular weight, which completely cover the cell surface forming a two-dimensional, regular array having either oblique (p1, p2), square (p4) or hexagonal (p3, p6) symmetry. The subunits are held together and attached to the underlying cell surfac
Vollrechtsf higkeit, was nun? Neue Ausbildungsformen im BID-Wesen in sterreich
Gabriele Pum
Libreas : Library Ideas , 2005,
Abstract:
Trust between Boundary-Spanning Agents: The Role of Relational Competencies  [PDF]
Isabella Hatak, Dietmar Roessl
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.33001
Abstract:

Against the background of principal-agent and transaction-cost theoretical considerations, this study addresses the question whether relational competencies relate to trust within cooperative relationships, taking into account also situational and personal factors. In its conclusion, the study presents an experimentally confirmed model (n = 282) that shows the strong causal relationship between relational competencies and trust allowing boundary-spanning agents to exert influence on the development and maintenance of complex cooperative relationships characterized by long-term objectives.

Combined Ang-2 and VEGF Targeting Therapies in Renal Cell Carcinoma  [PDF]
Nikolett Molnar, Dietmar W. Siemann
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.49A2001
Abstract:

Angiogenesis, the growth of new vessels from pre-existing ones, is an important feature of tumor growth that has been exploited as a therapeutic target in oncology. Given its key role in facilitating blood vessel sprouting, VEGF has been a major focus of anti-angiogenic strategies, but the observation of resistance in some clinical trials utilizing such agents has led to a search for new or complementary targets in angiogenesis process. The Angiopoietin/Tie2 pathway and in particular the Angiopoietin-2 (Ang-2) ligand which is critically involved in the destabilization of normal vasculature, has been identified as one such target. The current study investigated the potential benefits of combining an Ang-2 targeted therapy with small molecule VEGF targeted agents (Sunitinib, Cediranib) in a human renal cell carcinoma model. The results showed that while both Ang-2 and VEGF interference on their own impaired tumor growth and new blood vessel formation, the combination of agents that targeted both pathways resulted in significantly superior anti-tumor and anti-angiogenic effects.

Quantum Measurements Generating Structures of Numerical Events  [PDF]
Dietmar Dorninger, Helmut L?nger
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.65085
Abstract: Let S be a set of states of a physical system and p(s) the probability of an occurrence of an event when the system is in state s∈S. The function p from S to [0,1] is called a numerical event, multidimensional probability or, more precisely, S-probability. If a set of numerical events is ordered by the order of real functions one obtains a partial ordered set P in which the sum and difference of S-probabilities are related to their order within P. According to the structure that arises, this further opens up the opportunity to decide whether one deals with a quantum mechanical situation or a classical one. In this paper we focus on the situation that P is generated by a given set of measurements, i.e. S-probabilities, without assuming that these S-probabilities can be complemented by further measurements or are embeddable into Boolean algebras, assumptions that were made in most of the preceding papers. In particular, we study the generation by S-probabilities that can only assume the values 0 and 1, thus dealing with so called concrete logics. We characterize these logics under several suppositions that might occur with measurements and generalize our findings to arbitrary S-probabilities, this way providing a possibility to distinguish between potential classical and quantum situations and the fact that an obtained structure might not be sufficient for an appropriate decision. Moreover, we provide some explanatory examples from physics.
Which is the best?: Re-ranking Answers Merged from Multiple Web Sources
Hyo-Jung Oh,Pum-Mo Ryu,Hyunki Kim
Journal of Emerging Technologies in Web Intelligence , 2012, DOI: 10.4304/jetwi.4.1.35-42
Abstract: The main motivation of this paper is to devise a way to select the best answers collected from multiple web sources. Depending on questions, we need to combine multiple QA modules. To this end, we analyze real-life questions for their characteristics and classify them into different domains and genres. In the proposed distributed QA framework, local optimal answers are selected by several specialized sub-QAs. For fining global optimal answers, merged candidates are re-ranked by adjusting confidence weights based on the question analysis. We adopt the idea of the margin separation of SVM classification algorithm to adjust confidence weights calculated by own ranking methods in sub-QAs. We also prove the effects of the proposed re-ranking algorithm based on a series of experiments.
The development of drugs for treatment of sleeping sickness: a historical review
Dietmar Steverding
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-15
Abstract: Human African trypanosomiasis or sleeping sickness is a disease caused by two subspecies of Trypanosoma brucei, T. b. rhodesiense and T. b. gambiense. The parasites live and multiply extracellularly in blood and tissue fluids of their human host and are transmitted by the bite of infected tsetse flies (Glossina spp.). The occurrence of sleeping sickness is restricted to the distribution of tsetse flies which are exclusively found in sub-Saharan Africa between 14°N and 20°S [1]. More than 250 discrete active sleeping sickness foci in 36 African countries are recognised most of which are in rural areas [2].Trypanosoma b. rhodesiense is found in East and southern Africa whereas T. b. gambiense occurs in West and Central Africa. The course of sleeping sickness is different depending on the subspecies. Infections with T. b. rhodesiense lead to an acute form of the disease while infections with T. b. gambiense give rise to a chronic infection. The symptoms of the first stage of the disease, defined by the restriction of trypanosomes to the blood and lymph system, include fever, headache, joint pain and itching [3,4]. The clinical signs of the second stage of the disease, characterised by the invasion of trypanosomes into the central nervous system, are neurological and endocrinal disorders [3,4]. If left untreated, sleeping sickness patients infected with T. b. rhodesiense will die within months whereas those infected with T. b. gambiense usually survive for several years.In the late 19th Century, Africa experienced several sleeping sickness epidemics the most devastating of which was an epidemic with 300,000 to 500,000 deaths between 1896 and 1906 which mainly affected the Congo Basin and the Busoga focus in Uganda and Kenya [5]. The disastrous effect of this epidemic persuaded the various colonial administrations to call for their medical scientists to develop a cure for sleeping sickness. At that time, the field of chemotherapy was developing and had begun to make use
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