1
|
Möller AM, Vázquez-Hernández M, Kutscher B, Brysch R, Brückner S, Marino EC, Kleetz J, Senges CHR, Schäkermann S, Bandow JE, Narberhaus F. Common and varied molecular responses of Escherichia coli to five different inhibitors of the lipopolysaccharide biosynthetic enzyme LpxC. J Biol Chem 2024; 300:107143. [PMID: 38458396 PMCID: PMC10998244 DOI: 10.1016/j.jbc.2024.107143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/19/2024] [Accepted: 02/21/2024] [Indexed: 03/10/2024] Open
Abstract
A promising yet clinically unexploited antibiotic target in difficult-to-treat Gram-negative bacteria is LpxC, the key enzyme in the biosynthesis of lipopolysaccharides, which are the major constituents of the outer membrane. Despite the development of dozens of chemically diverse LpxC inhibitor molecules, it is essentially unknown how bacteria counteract LpxC inhibition. Our study provides comprehensive insights into the response against five different LpxC inhibitors. All compounds bound to purified LpxC from Escherichia coli. Treatment of E. coli with these compounds changed the cell shape and stabilized LpxC suggesting that FtsH-mediated proteolysis of the inactivated enzyme is impaired. LpxC inhibition sensitized E. coli to vancomycin and rifampin, which poorly cross the outer membrane of intact cells. Four of the five compounds led to an accumulation of lyso-phosphatidylethanolamine, a cleavage product of phosphatidylethanolamine, generated by the phospholipase PldA. The combined results suggested an imbalance in lipopolysaccharides and phospholipid biosynthesis, which was corroborated by the global proteome response to treatment with the LpxC inhibitors. Apart from LpxC itself, FabA and FabB responsible for the biosynthesis of unsaturated fatty acids were consistently induced. Upregulated compound-specific proteins are involved in various functional categories, such as stress reactions, nucleotide, or amino acid metabolism and quorum sensing. Our work shows that antibiotics targeting the same enzyme do not necessarily elicit identical cellular responses. Moreover, we find that the response of E. coli to LpxC inhibition is distinct from the previously reported response in Pseudomonas aeruginosa.
Collapse
Affiliation(s)
- Anna-Maria Möller
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | | | - Blanka Kutscher
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Raffael Brysch
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Simon Brückner
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Emily C Marino
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Julia Kleetz
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Christoph H R Senges
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Sina Schäkermann
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Julia E Bandow
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Franz Narberhaus
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany.
| |
Collapse
|
2
|
Brückner S, Müller F, Schadowski L, Kalle T, Weber S, Marino EC, Kutscher B, Möller AM, Adler S, Begerow D, Steinchen W, Bange G, Narberhaus F. (p)ppGpp and moonlighting RNases influence the first step of lipopolysaccharide biosynthesis in Escherichia coli. Microlife 2023; 4:uqad031. [PMID: 37426605 PMCID: PMC10326835 DOI: 10.1093/femsml/uqad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/12/2023] [Accepted: 06/13/2023] [Indexed: 07/11/2023]
Abstract
The outer membrane (OM) protects Gram-negative bacteria from harsh environmental conditions and provides intrinsic resistance to many antimicrobial compounds. The asymmetric OM is characterized by phospholipids in the inner leaflet and lipopolysaccharides (LPS) in the outer leaflet. Previous reports suggested an involvement of the signaling nucleotide ppGpp in cell envelope homeostasis in Escherichia coli. Here, we investigated the effect of ppGpp on OM biosynthesis. We found that ppGpp inhibits the activity of LpxA, the first enzyme of LPS biosynthesis, in a fluorometric in vitro assay. Moreover, overproduction of LpxA resulted in elongated cells and shedding of outer membrane vesicles (OMVs) with altered LPS content. These effects were markedly stronger in a ppGpp-deficient background. We further show that RnhB, an RNase H isoenzyme, binds ppGpp, interacts with LpxA, and modulates its activity. Overall, our study uncovered new regulatory players in the early steps of LPS biosynthesis, an essential process with many implications in the physiology and susceptibility to antibiotics of Gram-negative commensals and pathogens.
Collapse
Affiliation(s)
- Simon Brückner
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Fabian Müller
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Laura Schadowski
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Tyll Kalle
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Sophia Weber
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Emily C Marino
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Blanka Kutscher
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Anna-Maria Möller
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Sabine Adler
- Evolution of Plants and Fungi, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
| | - Dominik Begerow
- Evolution of Plants and Fungi, Faculty of Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, Bochum, Germany
- Organismische Botanik und Mykologie, Institut für Planzenwissenschaften und Mikrobiologie, Fachbereich Biologie, Universität Hamburg,Ohnhorststrasse 18, Hamburg, Germany
| | - Wieland Steinchen
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Karl-von-Frisch-Strasse 14, Marburg, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Karl-von-Frisch-Strasse 14, Marburg, Germany
| | - Franz Narberhaus
- Corresponding author. Faculty of Biology and Biotechnology, Microbial Biology, Ruhr University Bochum, Universitätsstrasse 150, NDEF 06/784, 44780 Bochum, Germany. Tel: +492343223100; Fax: +492343214620; E-mail:
| |
Collapse
|
3
|
Möller AM, Brückner S, Tilg LJ, Kutscher B, Nowaczyk MM, Narberhaus F. LapB (YciM) orchestrates protein-protein interactions at the interface of lipopolysaccharide and phospholipid biosynthesis. Mol Microbiol 2023; 119:29-43. [PMID: 36464488 DOI: 10.1111/mmi.15005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/14/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria functions as an essential barrier and is characterized by an asymmetric bilayer with lipopolysaccharide (LPS) in the outer leaflet. The enzyme LpxC catalyzes the first committed step in LPS biosynthesis. It plays a critical role in maintaining the balance between LPS and phospholipids (PL), which are both derived from the same biosynthetic precursor. The essential inner membrane proteins YejM (PbgA, LapC), LapB (YciM), and the protease FtsH are known to account for optimal LpxC levels, but the mechanistic details are poorly understood. LapB is thought to be a bi-functional protein serving as an adaptor for FtsH-mediated turnover of LpxC and acting as a scaffold in the coordination of LPS biosynthesis. Here, we provide experimental evidence for the physical interaction of LapB with proteins at the biosynthetic node from where the LPS and PL biosynthesis pathways diverge. By a total of four in vivo and in vitro assays, we demonstrate protein-protein interactions between LapB and the LPS biosynthesis enzymes LpxA, LpxC, and LpxD, between LapB and YejM, the anti-adaptor protein regulating LapB activity, and between LapB and FabZ, the first PL biosynthesis enzyme. Moreover, we uncovered a new adaptor function of LapB in destabilizing not only LpxC but also LpxD. Overall, our study shows that LapB is a multi-functional protein that serves as a protein-protein interaction hub for key enzymes in LPS and PL biogenesis presumably by virtue of multiple tetratricopeptide repeat (TPR) motifs in its cytoplasmic C-terminal region.
Collapse
Affiliation(s)
| | - Simon Brückner
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | | | | | | | | |
Collapse
|
4
|
Apolle R, Rehm M, Thiele J, Brückner S, Hampe J, Troost E. PO-0954: Fiducial markers and daily kV imaging improve patient setup during proton RT of esophageal cancer. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)31264-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
|
5
|
Henneke LE, Brückner S, Tautenhahn HM, Heß T, Schumacher J, Christ B. Charakterisierung der Akut-Phase Reaktion in humanen Lebergewebekulturen mittels transkriptomweiter Expressionsanalysen. Z Gastroenterol 2016. [DOI: 10.1055/s-0036-1597461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- LE Henneke
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Germany
| | - S Brückner
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Germany
| | - HM Tautenhahn
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Germany
| | - T Heß
- Universität Bonn, Institute of Human Genetics, Department of Genomics, Life and Brain Center, Bonn, Germany
| | - J Schumacher
- Universität Bonn, Institute of Human Genetics, Biomedical Center, Bonn, Germany
| | - B Christ
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Germany
| |
Collapse
|
6
|
Winkler S, Müller K, Brückner S, Hempel M, Schoon HA, Christ B. Mesenchymale Stammzellen vermindern die durch Diethylnitrosamin induzierte Entstehung prä-neoplastischer Foci in der Mausleber. Z Gastroenterol 2016. [DOI: 10.1055/s-0036-1597483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- S Winkler
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Deutschland
| | - K Müller
- Universität Leipzig, Institut für Veterinär-Pathologie, Leipzig, Deutschland
| | - S Brückner
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Deutschland
| | - M Hempel
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Deutschland
| | - HA Schoon
- Universität Leipzig, Institut für Veterinär-Pathologie, Leipzig, Deutschland
| | - B Christ
- Universität Leipzig, Klinik und Poliklinik für Viszeral-, Transplantations-, Thorax- und Gefäßchirurgie, Angewandte Molekulare Hepatologie, Leipzig, Deutschland
| |
Collapse
|
7
|
Tautenhahn HM, Brückner S, Pankow F, Uder C, Brach J, Gittel C, Hempel M, Berthold C, Lange UG, Broschewitz J, Dietel C, Bartels M, Pietsch UC, Christ B. Stammzelltherapie bei ausgedehnter Leberresektion im Schwein. Z Gastroenterol 2015. [DOI: 10.1055/s-0035-1568061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
8
|
Winkler S, Hempel M, Brückner S, Mallek F, Weise A, Liehr T, Tautenhahn HM, Bartels M, Christ B. Mouse white adipose tissue-derived mesenchymal stem cells gain pericentral and periportal hepatocyte features after differentiation in vitro, which are preserved in vivo after hepatic transplantation. Acta Physiol (Oxf) 2015; 215:89-104. [PMID: 26235702 DOI: 10.1111/apha.12560] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 07/17/2015] [Accepted: 07/29/2015] [Indexed: 12/13/2022]
Abstract
AIM Mesenchymal stem cells may differentiate into hepatocyte-like cells in vitro and in vivo. Therefore, they are considered a novel cell resource for the treatment of various liver diseases. Here, the aim was to demonstrate that mesenchymal stem cells may adopt both perivenous and periportal hepatocyte-specific functions in vitro and in vivo. METHODS Adipose tissue-derived mesenchymal stem cells were isolated from immunodeficient C57BL/6 (B6.129S6-Rag2(tm1Fwa) Prf1(tm1Clrk) ) mice and differentiated into the hepatocytic phenotype by applying a simple protocol. Their physiological and metabolic functions were analysed in vitro and after hepatic transplantation in vivo. RESULTS Mesenchymal stem cells changed their morphology from a fibroblastoid into shapes of osteocytes, chondrocytes, adipocytes and hepatocytes. Typical for mesenchymal stem cells, hematopoietic marker genes were not expressed. CD90, which is not expressed on mature hepatocytes, decreased significantly after hepatocytic differentiation. Markers indicative for liver development like hepatic nuclear factor 4 alpha, or for perivenous hepatocyte specification like cytochrome P450 subtype 3a11, and CD26 were significantly elevated. Periportal hepatocyte-specific markers like carbamoylphosphate synthetase 1, the entry enzyme of the urea cycle, were up-regulated. Consequently, cytochrome P450 enzyme activity and urea synthesis increased significantly to values comparable to cultured primary hepatocytes. Both perivenous and periportal qualities were preserved after hepatic transplantation and integration into the host parenchyma. CONCLUSIONS Adult mesenchymal stem cells from adipose tissue differentiated into hepatocyte-like cells featuring both periportal and perivenous functions. Hence, they are promising candidates for the treatment of region-specific liver cell damage and may support organ regeneration in acute and chronic liver diseases.
Collapse
Affiliation(s)
- S. Winkler
- Applied Molecular Hepatology Laboratory; Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
| | - M. Hempel
- Applied Molecular Hepatology Laboratory; Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
| | - S. Brückner
- Applied Molecular Hepatology Laboratory; Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
| | - F. Mallek
- Jena University Hospital; Institute of Human Genetics; Friedrich Schiller University; Jena Germany
| | - A. Weise
- Jena University Hospital; Institute of Human Genetics; Friedrich Schiller University; Jena Germany
| | - T. Liehr
- Jena University Hospital; Institute of Human Genetics; Friedrich Schiller University; Jena Germany
| | - H.-M. Tautenhahn
- Applied Molecular Hepatology Laboratory; Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
- Translational Centre for Regenerative Medicine (TRM); University of Leipzig; Leipzig Germany
- Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
| | - M. Bartels
- Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
| | - B. Christ
- Applied Molecular Hepatology Laboratory; Department of Visceral, Transplantation, Thoracic and Vascular Surgery; University Hospital of Leipzig; Leipzig Germany
- Translational Centre for Regenerative Medicine (TRM); University of Leipzig; Leipzig Germany
| |
Collapse
|
9
|
Brückner S, Kammer T. P69. Does theta burst stimulation on visual cortex only modulate phosphene threshold after high visual demand? Clin Neurophysiol 2015. [DOI: 10.1016/j.clinph.2015.04.203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
10
|
Ehrhard D, Brückner S, Kammer T. P151. The effects of occipital tDCS on phosphene thresholds in dependence of visual demand. Clin Neurophysiol 2015. [DOI: 10.1016/j.clinph.2015.04.221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
11
|
May T, Pfäfflin M, Brückner S, Lutz M, Schade B, Coban I, Faulmüller A. Behandlungserfolg bei stationären Patienten in diakonischen Epilepsiezentren. Z Epileptol 2015. [DOI: 10.1007/s10309-014-0388-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
12
|
Brückner S, Tautenhahn HM, Winkler S, Stock P, Jonas S, Dollinger M, Christ B. Isolation and hepatocyte differentiation of mesenchymal stem cells from porcine bone marrow--"surgical waste" as a novel MSC source. Transplant Proc 2014; 45:2056-8. [PMID: 23769107 DOI: 10.1016/j.transproceed.2013.01.101] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/15/2013] [Accepted: 01/31/2013] [Indexed: 12/17/2022]
Abstract
Mesenchymal stem cells (MSC) isolated from bone marrow and differentiated into hepatocyte-like cells have increasingly gained attention for clinical cell therapy of liver diseases because of their high regenerative capacity. They are available from bone marrow aspirates of the os coxae after puncture of the crista iliaca or from bone marrow "surgical waste" gained from amputations or knee and hip operations. Thus, the aim of the study was to demonstrate whether these pBM-MSC (porcine bone marrow-derived mesenchymal stem cells) displayed mesenchymal features and hepatocyte differentiation potential. MSC were isolated either from crista iliaca punctures or after sampling and collagenase digestion of bone marrow from the os femoris. Mesenchymal features were assessed by flow cytometry for specific surface antigens and their ability to differentiate into at least 3 lineages. Functional properties, such as urea or glycogen synthesis and cytochrome P450 activity, as well as the cell morphology were examined during hepatocyte differentiation. pBM-MSC from both sources lacked the hematopoietic markers CD14 and CD45 but expressed the typical mesenchymal markers CD44, CD29, CD90, and CD105. Both cell types could differentiate into adipocyte, osteocyte, and hepatocyte lineages. After hepatocyte differentiation, CD105 expression decreased significantly and cells changed morphology from fibroblastoid into polygonal, displaying significantly increased glycogen storage, urea synthesis, and cytochrome activity. pBM-MSC from various sources were identical in respect to their mesenchymal features and their hepatocyte differentiation potential. Hence, long bones might be a particularly useful resource to isolate bone marrow mesenchymal stem cells for transplantation.
Collapse
Affiliation(s)
- S Brückner
- University Hospital Leipzig, Department of Visceral, Transplantation, Thoracic and Vascular Surgery, Leipzig, Germany
| | | | | | | | | | | | | |
Collapse
|
13
|
Brückner S, Kiefer M, Kammer T. P 57. Continuous theta burst stimulation in a cognitive task: Virtual lesion comparable to 1Hz TMS? Clin Neurophysiol 2013. [DOI: 10.1016/j.clinph.2013.04.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
14
|
Brückner S, Kammer T. P 47. Does intermittent theta burst stimulation on visual cortex modulate visual acuity? Clin Neurophysiol 2013. [DOI: 10.1016/j.clinph.2013.04.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
15
|
Brückner S, Kiefer M, Kammer T. Comparing the after-effects of continuous theta burst stimulation and conventional 1Hz rTMS on semantic processing. Neuroscience 2013; 233:64-71. [DOI: 10.1016/j.neuroscience.2012.12.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/07/2012] [Accepted: 12/07/2012] [Indexed: 01/08/2023]
|
16
|
Wuttke C, Becker M, Brückner S, Rothhardt M, Rauschenbeutel A. Nanofiber Fabry-Perot microresonator for nonlinear optics and cavity quantum electrodynamics. Opt Lett 2012; 37:1949-1951. [PMID: 22660083 DOI: 10.1364/ol.37.001949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and cavity quantum electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications.
Collapse
Affiliation(s)
- C Wuttke
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Wien, Austria
| | | | | | | | | |
Collapse
|
17
|
Brumm T, Möps A, Dolainsky C, Brückner S, Bayerl TM. Macroscopic orientation effects in broadline NMR-spectra of model membranes at high magnetic field strength: A method preventing such effects. Biophys J 2010; 61:1018-24. [PMID: 19431822 DOI: 10.1016/s0006-3495(92)81909-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The partial orientation of multilamellar vesicles (MLV) in high magnetic fields has been studied and a method to prevent such effects is herewith proposed. The orientation effect was measured with (2)H-, (31)P-NMR and electron microscopy on MLVs of dipalmitoyl phosphatidylcholine with 30 mol% cholesterol. We present the first freeze-etch electron microscopy data obtained from MLV samples that were frozen directly in the NMR magnet at a field strength of 9.4 Tesla. These experiments clearly show that the MLVs adopt an ellipsoidal (but not a cylindrical) shape in the magnetic field. Best fit (31)P-NMR lineshape calculations assuming an ellipsoidal distribution of molecular director axes to the experimentally obtained spectra provide a quantitative measure of the average semiaxis ratio of the ellipsoidal MLVs and its change with temperature. The application of so-called spherical supported vesicles (SSV) is found to prevent any partial orientation effects so that undistorted NMR powder pattern of the bilayer can be measured independently of magnetic field strength and temperature.The usefulness of SSVs is further demonstrated by a direct comparison of spectral data such as (31)P-and (2)H-NMR lineshapes and relaxation times as well as (2)H-NMR dePaked spectra obtained for both model systems. These experiments show that spectral data obtained from partially oriented MLVs are not unambiguous to interpret, in particular, if an external parameter such as temperature is varied.
Collapse
Affiliation(s)
- T Brumm
- Technische Universität München, Physik Department E22, D-W 8046 Garching
| | | | | | | | | |
Collapse
|
18
|
Rothhardt J, Hädrich S, Gottschall T, Limpert J, Tünnermann A, Rothhardt M, Becker M, Brückner S, Bartelt H. Generation of flattop pump pulses for OPCPA by coherent pulse stacking with fiber Bragg gratings. Opt Express 2009; 17:16332-16341. [PMID: 19724632 DOI: 10.1364/oe.17.016332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a simple and robust pulse shaping device based on coherent pulse stacking. The device is embedded in a polarisation maintaining step index fiber. An input pulse is sent through a fiber optical circulator. Up to four pulse replicas are reflected by fiber Bragg gratings and interfere at the output. Temperature control allows tuning of the relative pulse phases of the sub-pulses. Additionally fine tuning of the sub-pulse amplitudes is demonstrated. We experimentally generated 235 ps and 416 ps long flattop pulses with rising and falling edges shorter than 100 ps. In contrast to other pulse shaping techniques the presented setup is robust, alignment free, provides excellent beam quality and is also suitable for pulse durations up to several nanoseconds.
Collapse
Affiliation(s)
- J Rothhardt
- Friedrich Schiller University Jena, Institute of Applied Physics, Albert-Einstein-Str. 15, 07745 Jena, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Stölzel F, Pursche S, Brückner S, Bornhäuser M, Ehninger G, Schaich M. Yersinia pseudotuberculosis causing abscesses in a 31-year-old patient in the post-immunosuppression period after allogeneic HSCT. Bone Marrow Transplant 2008; 43:515-6. [DOI: 10.1038/bmt.2008.357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
20
|
Madisch A, Schmolders J, Brückner S, Aust D, Miehlke S. Less favorable clinical outcome after diagnostic and interventional double balloon enteroscopy in patients with suspected small-bowel bleeding? Endoscopy 2008; 40:731-4. [PMID: 18698535 DOI: 10.1055/s-2008-1077521] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND STUDY AIMS Double balloon enteroscopy (DBE) is a new endoscopic technique that allows diagnosis and therapeutic interventions of small-bowel lesions. One of the main indications for DBE is suspected small-bowel bleeding (SSBB). Data about clinical outcome after DBE are limited. The aim of the present study was to prospectively assess the short-term clinical outcome of this procedure. PATIENTS AND METHODS Of all consecutive patients undergoing DBE for various indications, follow-up results in patients with SSBB were analyzed. Standardized questionnaires were used, including assessment of gastrointestinal symptoms, especially signs of gastrointestinal bleeding, blood transfusions, demand for re-intervention, and hospitalization. RESULTS Of a total of 180 DBEs performed in 124 patients during a 2-year period, SSBB was the indication in 84 patients (M/F = 46/38; mean age 63 years) who underwent a total of 111 DBEs. Of these patients 52 could be followed (mean follow-up 2 months, range 1-5 months). In this subgroup, positive findings were obtained in 30 (mostly angiodysplasia), with therapeutic interventions being performed in 18 of these patients. At follow-up, the rate of re-bleeding in patients who had undergone interventions (20%) was similar to that in patients who had not (18%). CONCLUSION In this pilot study, DBE did not seem to have a major effect on re-bleeding. Better patient selection or modification of therapeutic regimens appears to be necessary to better utilize DBE in SSBB.
Collapse
Affiliation(s)
- A Madisch
- Medical Department I, Technical University Hospital, Dresden, Germany.
| | | | | | | | | |
Collapse
|
21
|
Miehlke S, Tausche AK, Brückner S, Aust D, Morgner A, Madisch A. Retrieval of two retained endoscopy capsules with retrograde double-balloon enteroscopy in a patient with a history of complicated small-bowel disease. Endoscopy 2007; 39 Suppl 1:E157. [PMID: 17570097 DOI: 10.1055/s-2006-925375] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- S Miehlke
- Dept. of Medicine I and Institute of Pathology, Technical University of Dresden Hospital, Dresden, Germany.
| | | | | | | | | | | |
Collapse
|
22
|
Fellmer E, Brückner S. Der Tierarzt als gerichtlicher und außergerichtlicher Sachverständiger – Gutachten nach neuem Delikts- und Werkvertragsrecht. Tierarztl Prax Ausg G Grosstiere Nutztiere 2004. [DOI: 10.1055/s-0038-1623546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
23
|
Böhme A, Brückner S. Wann ist ein Tier »gebraucht«? Überlegungen zu einer Kuriosität des neuen Kaufrechts. Tierarztl Prax Ausg G Grosstiere Nutztiere 2003. [DOI: 10.1055/s-0038-1622957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
ZusammenfassungUnter der Voraussetzung, dass es sich um einen »gebrauchten « Kaufgegenstand handelt, kann der unternehmerisch tätige Verkäufer die Verjährungsfrist von zwei Jahren auf 12 Monate reduzieren. Wann aber sind Tiere gebraucht? Die Autoren setzen sich in dem vorliegenden Beitrag mit den fragmentarischen Antworten der Rechtsprechung sowie den denktheoretisch möglichen und praxisrelevanten Lösungsansätzen kritisch auseinander. Aufgrund der hierdurch gewonnenen Erkenntnisse wird schließlich ein eigener Vorschlag unterbreitet.
Collapse
|
24
|
Funke K, Banhatti RD, Brückner S, Cramer C, Krieger C, Mandanici A, Martiny C, Ross I. Ionic motion in materials with disordered structures: conductivity spectra and the concept of mismatch and relaxation. Phys Chem Chem Phys 2002. [DOI: 10.1039/b200122p] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
25
|
Allegra G, Brückner S. Copolymer Chain Statistics. The Pseudo-Stereochemical Equilibrium Approach within the Continuum of Rotational States. The Unperturbed Dimensions of Atactic Polypropylene. Macromolecules 2002. [DOI: 10.1021/ma60055a022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
26
|
Roth-Isigkeit A, Ocklitz E, Brückner S, Ros A, Dibbelt L, Friedrich HJ, Gehring H, Schmucker P. Development and evaluation of a video program for presentation prior to elective cardiac surgery. Acta Anaesthesiol Scand 2002; 46:415-23. [PMID: 11952443 DOI: 10.1034/j.1399-6576.2002.460415.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND : The objective of the present study was to develop and evaluate the effects of a preparatory videotape on endocrine stress responses of patients prior to cardiac surgery and to analyze patient acceptance of this video for preoperative preparation. METHODS : 101 male patients prior to elective cardiac surgery were enrolled into the study. On the day before surgery, patients were assigned to one of the following groups: group 1 (n = 51) saw a video with realistic information about the upcoming perioperative procedure, and group 2 (n = 50) saw a video of the same length without surgery-related information. Venous blood was sampled before and 15 min after the video presentation. On the second postoperative day, patients filled in a questionnaire concerning their experiences of having preoperatively watched the video. RESULTS : After viewing the video, blood levels of cortisol, adrenocorticotropic hormone (ACTH), beta-endorphin, prolactin, epinephrine and norepinephrine in patients of group 1 were not significantly different compared to values measured before the video presentation. In patients of group 2, blood levels of cortisol, ACTH, prolactin and norepinephrine were significantly lower after video presentation compared to values obtained before the video. Patients of group 1 (compared to group 2) were significantly more often of the opinion that the video had helped in the preparation for surgery, and that they would like to repeat this adjunct preoperative video preparation in another similar situation. CONCLUSION : We conclude from our results that (i); cardiac surgical patients prefer preoperatively an adjunct surgery-related video preparation to a non-specific video presentation, and that (ii); preoperative preparation with realistic information about the upcoming medical procedure in patients undergoing cardiac surgery does not lead to an increase in endocrine stress hormone levels.
Collapse
Affiliation(s)
- A Roth-Isigkeit
- Department of Anesthesia, Medical University of Luebeck, Luebeck, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Roth-Isigkeit A, Hasselbach L, Ocklitz E, Brückner S, Ros A, Gehring H, Schmucker P, Rink L, Seyfarth M. Inter-individual differences in cytokine release in patients undergoing cardiac surgery with cardiopulmonary bypass. Clin Exp Immunol 2001; 125:80-8. [PMID: 11472429 PMCID: PMC1906109 DOI: 10.1046/j.1365-2249.2001.01521.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response with secretion of cytokines (e.g. IL-6, TNF-alpha, IL-1 beta and sIL-2R). The objective of the following study was to investigate in vitro and in vivo cytokine responses and white blood cell counts (WBC) of patients with high versus low cytokine secretion after a coronary artery bypass grafting (CABG) procedure. Twenty male patients undergoing elective CABG surgery with CPB under general anaesthesia were enrolled in the study. On the day of surgery (postoperatively), serum levels of TNF-alpha and IL-1 beta were significantly higher in patients of the high IL-6 level group compared to the respective values in the patient group with low IL-6 levels. The inter-individual differences in IL-6 release in patients undergoing CABG surgery with CPB were accompanied by differences in the release of other cytokines, such as TNF-alpha, IL-1 beta and sIL-2R. To understand whether genetic background plays a role in influencing cytokine plasma levels under surgical stress, we examined the distribution of polymorphic elements within the promoter regions of the TNF-alpha and IL-6 genes, and determined their genotype regarding the BAT2 gene and TNF-beta intron polymorphisms. Our preliminary data suggests that regulatory polymorphisms in or near the TNF locus, more precisely the allele set 140/150 of the BAT2 microsatellite marker combined with the G allele at -308 of the TNF-alpha gene, could be one of the genetic constructions providing for a less sensitive response to various stimuli. Our results suggest: (1) close relationships between cytokine release in the postoperative period, and (2) inter-individually varying patterns of cytokine release in patients undergoing CABG surgery with CPB.
Collapse
Affiliation(s)
- A Roth-Isigkeit
- Department of Anaesthesia, Medical University of Luebeck, Luebeck, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Heringlake M, Brückner S, Schmucker P. Different batches of human albumin solutions from one manufacturer may induce heterogenous cardiovascular effects. Intensive Care Med 2000; 26:1011-2. [PMID: 10990124 DOI: 10.1007/s001340051300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
29
|
Abstract
Antiphospholipid antibodies (APAs) are considered risk factors in patients with thromboembolic diseases. Although the incidence of such acquired coagulation disturbances in adults are well described, only few data exist for children. Therefore, in a first step to collect new data we analyzed the presence of different APAs in 202 consecutive children and compared them with two groups of adults. The children screened for APA were exclusively those who did not have any thromboembolic complications or a tendency for thrombophilia due to other underlying diseases such as systemic lupus or malignancy in their past or present medical history. Consecutive blood samples were evaluated from routine laboratory specimens. The two groups of adults comprised 200 patients after deep vein thrombosis and 200 patients without thromboembolic events that served as controls. Four lupus anticoagulant (LA) screening tests were determined: the dilute Russell's viper venom test; a lupus anticoagulant-sensitive activated partial thromboplastin time reagent; a second lupus-sensitive activated partial thromboplastin time; and the Kaolin clotting time. Furthermore, three different antiphospholipid antibodies ELISA assays against cardiolipin (ACA), beta2-glycoprotein I, and phosphatidyl-serine, were determined. The children had a much higher prevalence for LA than did the adults. On the other hand, their values for ACA were significantly lower than in adults with a history of thromboembolism. Findings in children were similar to the normal adult group. This has to be taken into account when evaluating children with thromboembolic diseases.
Collapse
Affiliation(s)
- H J Siemens
- Department of Internal Medicine II, Lübeck, Germany.
| | | | | | | | | |
Collapse
|
30
|
Siemens HJ, Klüter H, Brückner S, Kirchner H, Katus HA, Wagner T. Evaluation of two new integrated adapters for blood drawing in closed blood bag systems: influence on different molecular coagulation markers. Transfus Med 1998; 8:325-32. [PMID: 9881427 DOI: 10.1046/j.1365-3148.1998.00167.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We compared a conventional blood donation bag system (A) with two newly developed ones (B, C) with integrated Y-shaped adapters. The new systems facilitate the withdrawal of blood samples in a closed system under aseptic conditions. The purpose of the study was to determine whether disturbances during blood donation in the different tubings influence the quality of the donated plasma due to activation processes of the coagulation system. In all bag samples from 34 probands for each system, we found higher levels of the global tests (aPTT, TT) compared to intraindividual controls. This was due to a greater amount of anticoagulant in the bag samples. An increase of procoagulant activity was demonstrated for bags A and C. Concerning the fibrinolytic system, values were reduced in all three systems compared to controls. In summary, the quality of the plasma in the three different bag devices was comparable to controls concerning factor activities measured as global tests. The activation of the coagulation system was only slightly higher in the new system B and C than in the conventional one (A). Therefore, the new closed systems are suitable for blood donation and reveal a high coagulation quality of the plasma.
Collapse
Affiliation(s)
- H J Siemens
- Department of Internal Medicine 2, Medical University at Lübeck, Germany
| | | | | | | | | | | |
Collapse
|
31
|
Abstract
Neurons in the avian nucleus laminaris (NL) are the first to receive binaural information and are presumed to play a role in encoding interaural time differences (ITD). NL not only receives excitatory projections from the ipsi- and contralateral nucleus magnocellularis, but also receives inhibitory (GABAergic) input. This study investigates how GABA (gamma-aminobutyric acid) influences ITD coding in NL. Intracellular responses of chick NL neurons were studied in a brain slice preparation. Both excitatory inputs to NL were electrically activated and the delay between trains of bilateral stimuli (simulated-interaural time difference [s-ITD]) was varied. The resulting s-ITD functions were recorded in the presence of 0-75 microM GABA. The discharge rate of NL neurons varied with s-ITD. Cells responded maximally using s-ITDs at which the peak of the ipsi- and contralateral excitatory postsynaptic potentials occurred simultaneously (favourable s-ITD). At unfavourable s-ITDs, the discharge rates usually fell below unilateral levels. GABA had contrary effects on the s-ITD functions depending on the drug concentration. A low GABA dose enhanced excitability at favourable s-ITD, but not at unfavourable s-ITDs. In contrast, higher GABA concentrations diminished excitability. Moderate GABA concentrations had no consistent effect. These results suggest that the GABAergic input to NL will either increase or decrease the excitability of the NL neuron depending on the degree to which this GABAergic input is activated. A gain control hypothesis is presented in which the GABAergic input makes ITD processing in NL independent of the stimulus intensity by adjusting the excitability of NL neurons.
Collapse
Affiliation(s)
- S Brückner
- Department of Psychology, Florida State University, Tallahassee 32306-1270, USA
| | | |
Collapse
|
32
|
Heringlake M, Brückner S, Sieg P, Schmucker P. Hypertensive reaction to a certain batch of albumin 5%: a case report. Crit Care 1998. [PMCID: PMC3301317 DOI: 10.1186/cc205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
33
|
Brückner S, Immirzi A. DEBVIN– a program for Rietveld refinement with generalized coordinates subjected to geometrical restraints. J Appl Crystallogr 1997. [DOI: 10.1107/s0021889896013441] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
34
|
|
35
|
Abstract
The spatial distribution of neurons with different binaural response properties was studied in two isofrequency areas of the inferior colliculus (IC) of the gerbil (Meriones unguiculatus). Single units were recorded in dorsomedial-to-ventrolaterally oriented electrode penetrations at different rostrocaudal positions, within a low (1-2 kHz; N = 108) and a high (23-27 kHz; N = 90) 'iso-frequency' sheet. Response types were not equally represented within the two layers. Within low-frequency regions, 41% of the units were excited following sound stimulation of either ear (EE), 21% received an excitatory input from one and an inhibitory input from the other ear (EI), and 12% were monaural (E0), while within high-frequency regions the distribution was 20% EE, 47% EI and 18% E0. However, the spatial arrangement of EE, EI and E0, within the dorsomedial-to-ventrolateral extent of the isofrequency sheets, was on the whole comparable within the two regions: EE-units were accumulated dorsomedially and EI-units ventrolaterally in the respective isofrequency sheets. E0-units were distributed equally within the low-frequency sheet but occurred more frequently in the middle part of the high-frequency lamina. About equal proportions of the units (low frequencies 9%; high frequencies 7%) had complex binaural response characteristics and were characterized as E/IE. In the rostrocaudal dimension of the nucleus, orderly arrangement of different unit types was less obvious. The results show that there is a tendency for grouping of different binaural unit types within the inferior colliculus. However, these unit types are not strictly segregated. Furthermore, it was shown that, despite the differences found in low- and high-frequency sites, there is a common scheme of 'binaural representation' across frequencies within the IC. Provided that EE-, EI-, and monaural response characteristics originate from separate sources, the data point to a convergence of binaural brainstem afferents within the IC.
Collapse
Affiliation(s)
- S Brückner
- Lehrstuhl für Allgemeine Zoologie und Neurobiologie, Ruhr-Universität Bochum, FRG
| | | |
Collapse
|
36
|
Abstract
Employing high-sensitivity differential scanning calorimetry (DSC), we discovered a pretransition in binary mixtures of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol, the main feature of which is its extraordinarily high transition enthalpy of 6.3 Kcal/mol, nearly an order of magnitude higher than those values previously found for such transitions. Using DSC, deuterium nuclear magnetic resonance, and electron microscopy, it is shown that the energetic origin of this type of pretransition is caused by interactions between the phospholipids in their headgroup region. The most likely interaction involves the formation of a hydrogen bond between the headgroups of the two phospholipid species in the gel (L beta') phase which is disrupted at the transition to the "ripple" (P beta') phase. The finding that this large pretransition is unique for mixtures of phosphocholine and phosphoglycerol with myristoyl chains indicates a dependence of the headgroup long range order of such mixtures in the gel phase on the acyl chain length.
Collapse
Affiliation(s)
- T M Bayerl
- Technische Universität München, Physik Department E22, Garching, Federal Republic of Germany
| | | | | |
Collapse
|
37
|
Bigi A, Ripamonti A, Brückner S, Gazzano M, Roveri N, Thomas SA. Structure refinements of lead-substituted calcium hydroxyapatite by X-ray powder fitting. Acta Crystallogr B Struct Sci 1989. [DOI: 10.1107/s0108768189001928] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
38
|
Meille S, Brückner S, Lando J. The structure of γ-polypivalolactone: a combined analysis of single-crystal electron diffraction data and powder X-ray diffraction profiles with the Rietveld method. POLYMER 1989. [DOI: 10.1016/0032-3861(89)90174-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
39
|
Leeser R, Brückner S. Prolonged anaesthesia of the N. Femoralis. Pain 1987. [DOI: 10.1016/0304-3959(87)91833-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
40
|
Klose G, Brückner S, Bezzabotnov V, Borbely S, Ostanevich Y. Hydration and swelling of the total lipid fraction of egg yolk and the influence of some additives studied by small-angle neutron scattering. Chem Phys Lipids 1986. [DOI: 10.1016/0009-3084(86)90027-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
41
|
Brückner S. [Regression of left heart hypertrophy with clonidine. Prevention of hypertensive heart disease]. Fortschr Med 1986; 104:522-4. [PMID: 3744261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
42
|
Brückner S, Malpezzi L, Prosyanik AV, Bondarenko SV. The structures of two crystalline forms of 1-phenyl-2,2-aziridinedicarboxamide, C10H11N3O2. Acta Crystallogr C 1985. [DOI: 10.1107/s0108270185003389] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
43
|
Brückner S, Malpezzi L, Prosyanik AV, Bondarenko SV. The structure of diethyl 1-(p-methoxyphenylsulphonyl)-2,2-aziridinedicarboxylate, C15H19NO7S. Acta Crystallogr C 1985. [DOI: 10.1107/s0108270185003390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
44
|
Brückner S, Malpezzi L, Prosyanik AV, Bondarenko SV. The structure of 1-methyl-2,2-aziridinedicarboxamide, C5H9N3O2. Acta Crystallogr C 1985. [DOI: 10.1107/s0108270185003377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
45
|
Kozinskij VA, Zelenskaja OV, Brückner S, Malpezzi L. A new mesoionic thia-sydnone-arylimine system. Synthesis and molecular structure. J Heterocycl Chem 1984. [DOI: 10.1002/jhet.5570210661] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
46
|
Barbarella G, Brückner S, Pitacco G, Valentin E. Polyfunctionalized hexahydro-1 (2H)-pentalenones by rearrangement of bicyclic 1,2-oxazine N-oxide derivatives. Tetrahedron 1984. [DOI: 10.1016/s0040-4020(01)83495-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
47
|
Brückner S, Malpezzi L, Grassi M. Structure of tetramethyl bicyclo[2.2.2]oct-5-ene-2-endo,3-exo,7-endo,8-exo-tetracarboxylate, C16H20O8. Acta Crystallogr C 1983. [DOI: 10.1107/s0108270183005570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
48
|
|
49
|
Brückner S. An unusual example of packing among molecular layers: the structures of two crystalline forms of 2,2-aziridinedicarboxamide, C4H7N3O2. ACTA ACUST UNITED AC 1982. [DOI: 10.1107/s0567740882008887] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
50
|
Brückner S, Malpezzi Giunchi L, Di Silvestro G, Grassi M. The structures of 1,2,3,4,5,6-cis-cyclohexanehexacarboxylic acid and its hexamethyl ester. ACTA ACUST UNITED AC 1981. [DOI: 10.1107/s0567740881003622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|