21 results on '"Frank, Bernhard"'
Search Results
2. Das Konformationsgleichgewicht des Neuropeptid‐Y2‐Rezeptors in Lipidmembranen
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Daniel Huster, Anika Gloge, Anette Kaiser, Clemens Glaubitz, Frank Bernhard, Ulrike Krug, Vsevolod V. Gurevich, Marcel Gauglitz, Johanna Becker-Baldus, Cindy Montag, Sergey A. Vishnivetskiy, Annette G. Beck-Sickinger, and Peter Schmidt
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Chemistry ,General Medicine - Published
- 2020
3. The Conformational Equilibrium of the Neuropeptide Y2 Receptor in Bilayer Membranes
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Clemens Glaubitz, Frank Bernhard, Cindy Montag, Johanna Becker-Baldus, Sergey A. Vishnivetskiy, Vsevolod V. Gurevich, Ulrike Krug, Peter Schmidt, Marcel Gauglitz, Daniel Huster, Anette Kaiser, Annette G. Beck-Sickinger, and Anika Gloge
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Models, Molecular ,Molecular Conformation ,receptors ,Receptors | Hot Paper ,010402 general chemistry ,01 natural sciences ,Catalysis ,NMR spectroscopy ,Extracellular ,Arrestin ,Humans ,Research Articles ,Molecular switch ,arrestin ,010405 organic chemistry ,Chemistry ,Bilayer ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,Carbon-13 NMR ,structural dynamics ,Neuropeptide Y receptor ,Receptors, Neuropeptide Y ,molecular switch ,0104 chemical sciences ,Membrane ,Biophysics ,500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften ,Research Article - Abstract
Dynamic structural transitions within the seven‐transmembrane bundle represent the mechanism by which G‐protein‐coupled receptors convert an extracellular chemical signal into an intracellular biological function. Here, the conformational dynamics of the neuropeptide Y receptor type 2 (Y2R) during activation was investigated. The apo, full agonist‐, and arrestin‐bound states of Y2R were prepared by cell‐free expression, functional refolding, and reconstitution into lipid membranes. To study conformational transitions between these states, all six tryptophans of Y2R were 13C‐labeled. NMR‐signal assignment was achieved by dynamic‐nuclear‐polarization enhancement and the individual functional states of the receptor were characterized by monitoring 13C NMR chemical shifts. Activation of Y2R is mediated by molecular switches involving the toggle switch residue Trp2816.48 of the highly conserved SWLP motif and Trp3277.55 adjacent to the NPxxY motif. Furthermore, a conformationally preserved “cysteine lock”‐Trp11623.50 was identified., Structural transitions of crucial molecular switches of the activation of the human neuropeptide Y receptor type 2 are reported from the 13C‐tryptophan labeled molecule by solid‐state NMR spectroscopy in lipid membranes. The molecule shows high structural dynamics in the apo and agonist‐bound states, which is reduced by arrestin binding.
- Published
- 2020
4. The synaptic vesicle protein SV31 assembles into a dimer and transports Zn2+
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Lisa Waberer, Erik Henrich, Volker Dötsch, Nina Morgner, Walter Volknandt, Frank Bernhard, and Oliver Peetz
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inorganic chemicals ,0301 basic medicine ,chemistry.chemical_classification ,Dimer ,Mutagenesis ,Chemical modification ,Biochemistry ,Synaptic vesicle ,Divalent ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,biological sciences ,Aspartic acid ,health occupations ,Biophysics ,bacteria ,Histidine ,Nanodisc - Abstract
The integral synaptic vesicle protein SV31 has been shown to bind divalent cations. Here we demonstrate that SV31 protein synthesized within a cell-free system binds Zn2+ and to a lower extent Ni2+ and Cu2+ ions. Expression with Zn2+ stabilized the protein and increased solubility. SV31 was preferentially monomeric in detergent and revealed specific binding of Zn2+. When co-translationally inserted into defined nanodisc bilayers, SV31 assembled into dimeric complexes, resulting in increased binding of Zn2+. Putative Zn2+-binding motifs within SV31 comprise aspartic acid and histidine residues. Site-directed mutagenesis of two conserved aspartic acid residues lead to a potent decrease in Zn2+ binding but did not affect dimerization. Chemical modification of histidine residues abolished some of the Zn2+ binding capacity. We demonstrate proton-dependent transport of Zn2+ as by accumulation of fluorescent FluoZin-1 inside of SV31-containing proteoliposomes. Transport activity has a Km value of 44.3 μM and required external Zn2+ and internal acidic pH. Our results demonstrate that the synaptic vesicle-integral protein SV31 functions as a proton-dependent Zn2+-transporter. SV31 may attribute specific and yet undiscovered functions to subsets of synapses. This article is protected by copyright. All rights reserved.
- Published
- 2016
5. Innentitelbild: Das Konformationsgleichgewicht des Neuropeptid‐Y2‐Rezeptors in Lipidmembranen (Angew. Chem. 52/2020)
- Author
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Frank Bernhard, Anika Gloge, Annette G. Beck-Sickinger, Marcel Gauglitz, Vsevolod V. Gurevich, Ulrike Krug, Daniel Huster, Clemens Glaubitz, Johanna Becker-Baldus, Peter Schmidt, Sergey A. Vishnivetskiy, Anette Kaiser, and Cindy Montag
- Subjects
General Medicine - Published
- 2020
6. Inside Cover: The Conformational Equilibrium of the Neuropeptide Y2 Receptor in Bilayer Membranes (Angew. Chem. Int. Ed. 52/2020)
- Author
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Clemens Glaubitz, Anika Gloge, Ulrike Krug, Anette Kaiser, Annette G. Beck-Sickinger, Vsevolod V. Gurevich, Sergey A. Vishnivetskiy, Cindy Montag, Johanna Becker-Baldus, Peter Schmidt, Daniel Huster, Marcel Gauglitz, and Frank Bernhard
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Molecular switch ,Membrane ,Chemistry ,Bilayer ,Arrestin ,Biophysics ,Neuropeptide ,Cover (algebra) ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,Receptor ,Catalysis - Published
- 2020
7. Hydrophobic supplements in cell-free systems: Designing artificial environments for membrane proteins
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Erika Orbán, Frank Bernhard, Christopher Hein, Erik Henrich, and Volker Dötsch
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Reaction conditions ,Folding (chemistry) ,Environmental Engineering ,Membrane protein ,Biochemistry ,Chemistry ,Solubilization ,Bioengineering ,Computational biology ,Nanodisc ,Protein expression ,Biotechnology - Abstract
Membrane proteins (MPs) are of central interest for the pharmaceutical industry but their production is usually a challenging task. The complex folding mechanisms of newly synthesized MPs often require interactions with specific compounds for improved stability. Conditions for the production of high-quality samples are therefore difficult to predict and frequently cannot be provided in conventional protein expression platforms. Cell-free (CF) biosynthetic systems allow, in contrast to living cells, nonrestricted access to the protein production machinery. Reaction conditions can be adjusted according to particular requirements and modified by supplementing single additives or even cocktails of compounds. These options have initiated completely new research fields for the cotranslational stabilization and folding of MPs in artificial environments. Based on established and efficient CF production protocols, a recent focus was to explore and define suitable supplements for CF expression reactions that are useful for the generation of high-quality MP samples. Besides classical detergents and lipids, a variety of new compounds with interesting properties have been discovered and synthesized. We compile the currently available toolbox for MP solubilization in CF systems and summarize new developments and perspectives for the directed modulation of CF biosynthetic environments.
- Published
- 2014
8. Inhibition of microsomal prostaglandin E2 synthase-1 as a molecular basis for the anti-inflammatory actions of boswellic acids from frankincense
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Ulf Siemoneit, Antonietta Rossi, Thorsten J. Maier, Oliver Werz, Moritz Verhoff, Sina Reckel, Lidia Sautebin, Andreas Koeberle, V Doetsch, Friederike Dehm, Johann Jauch, Hinnak Northoff, and Frank Bernhard
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Pharmacology ,biology ,medicine.drug_class ,Prostaglandin ,Frankincense ,biology.organism_classification ,Anti-inflammatory ,chemistry.chemical_compound ,chemistry ,Eicosanoid ,Biochemistry ,In vivo ,medicine ,Boswellic acid ,Prostaglandin E2 ,Boswellia ,medicine.drug - Abstract
BACKGROUND AND PURPOSE Frankincense, the gum resin derived from Boswellia species, showed anti-inflammatory efficacy in animal models and in pilot clinical studies. Boswellic acids (BAs) are assumed to be responsible for these effects but their anti-inflammatory efficacy in vivo and their molecular modes of action are incompletely understood.
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- 2010
9. Production of membrane proteins using cell-free expression systems
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Volker Dötsch, Daniel Schwarz, and Frank Bernhard
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Proteomics ,Cell-free protein synthesis ,Cell-Free System ,High-throughput screening ,Gene Expression ,Membrane Proteins ,Computational biology ,Biology ,Models, Biological ,Biochemistry ,Transmembrane protein ,Expression (mathematics) ,Membrane protein ,Gene expression ,Protein Expression Analysis ,Animals ,Humans ,Molecular Biology - Abstract
Production of membrane proteins (MPs) is a challenging task as their hydrophobic nature and their specific requirements in cellular expression systems frequently prevent an efficient synthesis. Cell-free (CF) expression systems have been developed in recent times as promising tools by offering completely new approaches to synthesize MPs directly into artificial hydrophobic environments. A considerable variety of CF produced MPs has been characterized by functional and structural approaches and the high success rates and the rapidly accumulating data on quality and expression efficiencies increasingly attract attention. In addition, CF expression is a highly dynamic and versatile technique and new modifications for improved performance as well as for extended applications for the labeling, throughput expression and proteomic analysis of MPs are rapidly emerging.
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- 2008
10. Measuring zinc on the Roche cobas c502 analyzer-Validation, comparison, and pre-analytic aspects
- Author
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Kraus, Frank Bernhard, primary and Ludwig-Kraus, Beatrice, additional
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- 2017
- Full Text
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11. Similar but not consistent: Revisiting the pitfalls of measuring IgG subclasses with different assays
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Ludwig‐Kraus, Beatrice, primary and Kraus, Frank Bernhard, additional
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- 2017
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12. Functional analysis of cell-free-produced human endothelin B receptor reveals transmembrane segment 1 as an essential area for ET-1 binding and homodimer formation
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Friederike Junge, Volker Doetsch, Hartmut Michel, Michael Beyermann, Ankita Srivastava, Daniel Schwarz, Nora Eifler, Frank Bernhard, and Christian Klammt
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Biochemistry ,B-cell receptor ,5-HT5A receptor ,Cell Biology ,GABBR1 ,Biology ,Interleukin-13 receptor ,Receptor ,Molecular Biology ,Protease-activated receptor 2 ,Nuclear receptor co-repressor 1 ,G protein-coupled receptor - Abstract
The functional and structural characterization of G-protein-coupled receptors (GPCRs) still suffers from tremendous difficulties during sample preparation. Cell-free expression has recently emerged as a promising alternative approach for the synthesis of polytopic integral membrane proteins and, in particular, for the production of G-protein-coupled receptors. We have now analyzed the quality and functional folding of cell-free produced human endothelin type B receptor samples as an example of the rhodopsin-type family of G-protein-coupled receptors in correlation with different cell-free expression modes. Human endothelin B receptor was cell-free produced as a precipitate and subsequently solubilized in detergent, or was directly synthesized in micelles of various supplied mild detergents. Purified cell-free-produced human endothelin B receptor samples were evaluated by single-particle analysis and by ligand-binding assays. The soluble human endothelin B receptor produced is predominantly present as dimeric complexes without detectable aggregation, and the quality of the sample is very similar to that of the related rhodopsin isolated from natural sources. The binding of human endothelin B receptor to its natural peptide ligand endothelin-1 is demonstrated by coelution, pull-down assays, and surface plasmon resonance assays. Systematic functional analysis of truncated human endothelin B receptor derivatives confined two key receptor functions to the membrane-localized part of human endothelin B receptor. A 39 amino acid fragment spanning residues 93-131 and including the proposed transmembrane segment 1 was identified as a central area involved in endothelin-1 binding as well as in human endothelin B receptor homo-oligomer formation. Our approach represents an efficient expression technique for G-protein-coupled receptors such as human endothelin B receptor, and might provide a valuable tool for fast structural and functional characterizations.
- Published
- 2007
13. Cell-free expression as an emerging technique for the large scale production of integral membrane protein
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Daniel Schwarz, Frank Löhr, Birgit Schneider, Frank Bernhard, Christian Klammt, and Volker Dötsch
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Protein Folding ,Cell-Free System ,Protein Conformation ,Membrane transport protein ,Membrane Proteins ,Cell Biology ,Biology ,Membrane transport ,Biochemistry ,Transport protein ,Membrane protein ,Escherichia coli ,biology.protein ,Biophysics ,Animals ,Humans ,Receptor ,Overproduction ,Hydrophobic and Hydrophilic Interactions ,Molecular Biology ,Integral membrane protein ,Triticum ,G protein-coupled receptor - Abstract
Membrane proteins are highly underrepresented in structural data banks due to tremendous difficulties that occur upon approaching their structural analysis. Inefficient sample preparation from conventional cellular expression systems is in many cases the first major bottleneck. Preparative scale cell-free expression has now become an emerging alternative tool for the high level production of integral membrane proteins. Many toxic effects attributed to the overproduction of recombinant proteins are eliminated by cell-free expression as viable host cells are no longer required. A unique characteristic is the open nature of cell-free systems that offers a variety of options to manipulate the reaction conditions in order to protect or to stabilize the synthesized recombinant proteins. Detergents or lipids can easily be supplemented and membrane proteins can therefore be synthesized directly into a defined hydrophobic environment of choice that permits solubility and allows the functional folding of the proteins. Alternatively, cell-free produced precipitates of membrane proteins can efficiently be solubilized in mild detergents after expression. Highly valuable for structural approaches is the fast and efficient cell-free production of uniformly or specifically labeled proteins. A considerable number of membrane proteins from diverse families like prokaryotic small multidrug transporters or eukaryotic G-protein coupled receptors have been produced in cell-free systems in high amounts and in functionally active forms. We will give an overview about the current state of the art of this new approach with special emphasis on technical aspects as well as on the functional and structural characterization of cell-free produced membrane proteins.
- Published
- 2006
14. Combination of cell-free expression and NMR spectroscopy as a new approach for structural investigation of membrane proteins
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Volker Dötsch, Frank Bernhard, Alexander Koglin, Christian Klammt, Nikola Trbovic, Daniel Schwarz, Birgit Schäfer, Birgit Schneider, and Frank Löhr
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chemistry.chemical_classification ,Cell-Free System ,Chemistry ,Peripheral membrane protein ,Membrane Proteins ,General Chemistry ,Cell free ,Nuclear magnetic resonance spectroscopy ,Protein Structure, Secondary ,Amino acid ,Protein structure ,Biochemistry ,Membrane protein ,Solvents ,General Materials Science ,Protein–lipid interaction ,Nuclear Magnetic Resonance, Biomolecular ,Integral membrane protein - Abstract
Despite major technical advance in methods used for structural investigations of proteins structure determination of membrane proteins still poses a significant challenge. Recently, the application of cell-free expression systems to membrane proteins has demonstrated that this technique can be used to produce quantities sufficient for structural investigations for many different membrane proteins. In particular for NMR spectroscopy, cell-free expression provides major advantages since it allows for amino acid type selective and even amino acid position specific labeling. In this mini-review we discuss the combination of cell-free membrane protein expression and liquid state NMR spectroscopy. Copyright © 2006 John Wiley & Sons, Ltd.
- Published
- 2006
15. Evaluation of detergents for the soluble expression of α-helical and β-barrel-type integral membrane proteins by a preparative scale individual cell-free expression system
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Klaus Fendler, Winfried Haase, Daniel Schwarz, Frank Bernhard, Volker Dötsch, and Christian Klammt
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Vesicle-associated membrane protein 8 ,Membrane protein ,Biochemistry ,Peripheral membrane protein ,Denaturation (biochemistry) ,Cell Biology ,Biology ,Membrane transport ,Molecular Biology ,Integral membrane protein ,Transmembrane protein ,G protein-coupled receptor - Abstract
Cell-free expression has become a highly promising tool for the fast and efficient production of integral membrane proteins. The proteins can be produced as precipitates that solubilize in mild detergents usually without any prior denaturation steps. Alternatively, membrane proteins can be synthesized in a soluble form by adding detergents to the cell-free system. However, the effects of a representative variety of detergents on the production, solubility and activity of a wider range of membrane proteins upon cell-free expression are currently unknown. We therefore analyzed the cell-free expression of three structurally very different membrane proteins, namely the bacterial alpha-helical multidrug transporter, EmrE, the beta-barrel nucleoside transporter, Tsx, and the porcine vasopressin receptor of the eukaryotic superfamily of G-protein coupled receptors. All three membrane proteins could be produced in amounts of several mg per one ml of reaction mixture. In general, the detergent 1-myristoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] was found to be most effective for the resolubilization of membrane protein precipitates, while long chain polyoxyethylene-alkyl-ethers proved to be most suitable for the soluble expression of all three types of membrane proteins. The yield of soluble expressed membrane protein remained relatively stable above a certain threshold concentration of the detergents. We report, for the first time, the high-level cell-free expression of a beta-barrel type membrane protein in a functional form. Structural and functional variations of the analyzed membrane proteins are evident that correspond with the mode of expression and that depend on the supplied detergent.
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- 2005
16. High level cell-free expression and specific labeling of integral membrane proteins
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Winfried Haase, Birgit Schäfer, Heinz Rüterjans, Frank Bernhard, Clemens Glaubitz, Frank Löhr, Christian Klammt, and Volker Dötsch
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Circular dichroism ,Protein Conformation ,Proteolipids ,Detergents ,medicine.disease_cause ,Biochemistry ,Micelle ,medicine ,Freeze Fracturing ,Nuclear Magnetic Resonance, Biomolecular ,Escherichia coli ,Integral membrane protein ,DNA Primers ,chemistry.chemical_classification ,Base Sequence ,Cell-Free System ,Chemistry ,Circular Dichroism ,Escherichia coli Proteins ,Membrane Proteins ,Transporter ,Transmembrane protein ,Amino acid ,Microscopy, Electron ,Cysteine - Abstract
We demonstrate the high level expression of integral membrane proteins (IMPs) in a cell-free coupled transcription/translation system using a modified Escherichia coli S30 extract preparation and an optimized protocol. The expression of the E. coli small multidrug transporters EmrE and SugE containing four transmembrane segments (TMS), the multidrug transporter TehA with 10 putative TMS, and the cysteine transporter YfiK with six putative TMS, were analysed. All IMPs were produced at high levels yielding up to 2.7 mg of protein per mL of reaction volume. Whilst the vast majority of the synthesized IMPs were precipitated in the reaction mixture, the expression of a fluorescent EmrE-sgGFP fusion construct showed evidence that a small part of the synthesized protein 'remained soluble and this amount could be significantly increased by the addition of E. coli lipids into the cell-free reaction. Alternatively, the majority of the precipitated IMPs could be solubilized in detergent micelles, and modifications to the solubilization procedures yielded proteins that were almost pure. The folding induced by formation of the proposed alpha-helical secondary structures of the IMPs after solubilization in various micelles was monitored by CD spectroscopy. Furthermore, the reconstitution of EmrE, SugE and TehA into proteoliposomes was demonstrated by freeze-fracture electron microscopy, and the function of EmrE was additionally analysed by the specific transport of ethidium. The cell-free expression technique allowed efficient amino acid specific labeling of the IMPs with 15N isotopes, and the recording of solution NMR spectra of the solubilized EmrE, SugE and YfiK proteins further indicated a correctly folded conformation of the proteins.
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- 2004
17. The autoregulatory role of EsaR, a quorum-sensing regulator in Pantoea stewartii ssp. stewartii: evidence for a repressor function
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Frank Bernhard, Markus Wehland von Trebra, Susanne B. von Bodman, and Timothy D. Minogue
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Regulation of gene expression ,Quorum sensing ,Biochemistry ,Pantoea ,Repressor ,Inducer ,Biology ,biology.organism_classification ,Molecular Biology ,Microbiology ,Gene ,Derepression ,Palindromic sequence - Abstract
Capsular polysaccharide synthesis and virulence in the plant pathogenic bacterium Pantoea stewartii ssp. stewartii requires the quorum-sensing regulatory proteins, EsaR and EsaI, and the diffusible inducer N-(3-oxo-hexanoyl)-L-homoserine lactone. Prior mutational studies suggested that EsaR might function as a repressor of quorum sensing in the control of capsular polysaccharide synthesis. Further, a lux box-like palindromic sequence coinciding with the putative -10 element of the esaR promoter suggested a possible negative autoregulatory role for EsaR. This report presents genetic evidence that EsaR represses the esaR gene under inducer-limiting conditions, and that addition of inducer promotes rapid, dose-dependent derepression. DNA mobility-shift assays and analyses by surface plasmon resonance refractometry show that EsaR binds target DNAs in a ligand-free state, and that inducer alters the binding characteristics of EsaR. Physical measurements indicate that the EsaR protein binds N-(3-oxo-hexanoyl)-L-homoserine lactone, in a 1:1 protein:ligand ratio, and that inducer binding enhances the thermal stability of the EsaR protein. These combined genetic and biochemical data establish that EsaR regulates its own expression by signal-independent repression and signal-dependent derepression. Additionally, we provide evidence that EsaR does not govern the expression of the linked esaI gene, thus EsaR has no role in controlling coinducer synthesis.
- Published
- 2002
18. Male‐biased dispersal promotes large scale gene flow in a subterranean army ant, Dorylus (Typhlopone) fulvus
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Barth, Matthias Benjamin, primary, Moritz, Robin Frederik Alexander, additional, Pirk, Christian Walter Werner, additional, and Kraus, Frank Bernhard, additional
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- 2013
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19. The correlation of the Narcotrend Index with endtidal sevoflurane concentrations and hemodynamic parameters in children
- Author
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WEBER, FRANK, primary, HOLLNBERGER, HARALD, additional, GRUBER, MICHAEL, additional, FRANK, BERNHARD, additional, and TAEGER, KAI, additional
- Published
- 2005
- Full Text
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20. Automated immunohistochemistry of intra-epidermal nerve fibres in skin biopsies: A proof-of-concept study.
- Author
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Burgess J, Marshall A, Rapteas L, Hamill KJ, Marshall A, Malik RA, Frank B, and Alam U
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- Humans, Female, Male, Adult, Middle Aged, Biopsy, Epidermis innervation, Epidermis pathology, Aged, Ubiquitin Thiolesterase metabolism, Ubiquitin Thiolesterase analysis, Reproducibility of Results, Nerve Fibers pathology, Immunohistochemistry, Proof of Concept Study, Skin innervation, Skin pathology, Small Fiber Neuropathy diagnosis, Small Fiber Neuropathy pathology
- Abstract
Aims: To develop a standardised, automated protocol for detecting protein gene product 9.5 (PGP9.5) positive intra-epidermal nerve fibres (IENFs) in skin biopsies, transitioning from the established manual technique to an automated platform. This automated method, although currently intended for research applications, may improve the accessibility of this diagnostic test for small fibre neuropathy in clinical settings., Methods: Skin biopsies (n = 274) from 100 participants (fibromyalgia syndrome n = 62; idiopathic small fibre neuropathy: n = 16; healthy volunteers: n = 22) were processed using an automated immunohistochemistry platform. IENF quantification was performed by blinded examiners, with reliability assessed via a two-way mixed-effects model to evaluate inter- and intra-observer variability., Results: The automated staining system reproduced intra-epidermal nerve fibre density (IENFD) counts consistent with free-floating sections (mean ± standard deviation: free-floating: 5.6 ± 3.4 fibres/mm; automated: 5.9 ± 3.2 fibres/mm). A median difference of 0.3 with a lower bound 95% Confidence Interval (CI) at -0.00005 established non-inferiority against a margin of -0.4 (p = .08). Specifically, the inter-class correlation coefficient (class denotes consistency in measured observations) was 99% (95% CI: 0.9-1), indicating excellent agreement between free-floating and automated methods. The inter- and intra-class coefficient between examiners were both 99% (95% CI: 0.9-0.1) for IENFD, demonstrating high reliability using sections stained using the automated method., Interpretation: Automated immunohistochemistry provides high-throughput reliable and reproducible intra-epidermal nerve fibre quantification. This method, although currently proof-of-concept, for research use only, may be more widely deployed in histopathology laboratories to increase the adoption of IENFD assessment for the diagnosis of peripheral neuropathies., (© 2024 The Author(s). Journal of the Peripheral Nervous System published by Wiley Periodicals LLC on behalf of Peripheral Nerve Society.)
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- 2024
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21. Measuring zinc on the Roche cobas c502 analyzer-Validation, comparison, and pre-analytic aspects.
- Author
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Kraus FB and Ludwig-Kraus B
- Subjects
- Humans, Limit of Detection, Linear Models, Reproducibility of Results, Blood Chemical Analysis methods, Blood Chemical Analysis standards, Zinc blood
- Abstract
Objectives: Characterization of an in vitro diagnostic zinc assay (LT-SYS) on a Roche cobas c502 analyzer and evaluation of the influence of pre-analytic factors on zinc concentration measurements., Design and Methods: Imprecision, bias, linearity, limit of blank (LoB), and limit of detection (LoD) were established and method comparisons were performed based on the respective CLSI guidelines. The influence of time elapsed until analysis, the usage of a pneumatic tube delivery system (PTDS) and of special trace element sample tubes was evaluated as well., Results: Estimates of imprecision ranged from 0.9% to 5.0% and bias was low with 1.3% and 1.5% deviation from target value. Linearity was met for the measuring range of 1.15-34.7 μmol/L (7.51-226.9 μg/dL), LoB and LoD were 0.17 μmol/L (1.11 μg/dL) and 0.73 μmol/L (4.77 μg/dL) respectively. The method comparison revealed an average deviation of 8.44% (y=0.542+1.036x). Plasma samples had 7.3% higher zinc values than serum samples on the average. Zinc values of uncentrifuged serum and plasma samples increased 20% in 8 hours, while after centrifugation no significant increase could be detected. Usage of PTDS increased zinc values by 17% and usage of trace element sample tubes showed no advantage over normal ones., Conclusions: The LT-SYS zinc assay showed a fully acceptable performance with good degrees of imprecision and bias, no deviation from linearity and both a very low LoB and LoD. Samples for zinc analysis should be centrifuged timely and transport over PTDS should be avoided., (© 2017 Wiley Periodicals, Inc.)
- Published
- 2018
- Full Text
- View/download PDF
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