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Volkmann C, Plöderl M, Hengartner MP. Comment on Osler et al: Misinterpretation of pre-post differences invalidates the authors' conclusions. Acta Psychiatr Scand 2019; 140:589-590. [PMID: 31610010 DOI: 10.1111/acps.13110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 10/08/2019] [Indexed: 12/27/2022]
Affiliation(s)
- C Volkmann
- Department of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - M Plöderl
- Department of Crisis Intervention and Suicide Prevention, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria
| | - M P Hengartner
- Department of Applied Psychology, Zurich University of Applied Sciences, Zurich, Switzerland
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Volkmann C, Brings N, Becker M, Hobeika E, Yang J, Reth M. Molecular requirements of the B-cell antigen receptor for sensing monovalent antigens. EMBO J 2016; 35:2371-2381. [PMID: 27634959 PMCID: PMC5090217 DOI: 10.15252/embj.201694177] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 08/16/2016] [Indexed: 11/22/2022] Open
Abstract
How the B‐cell antigen receptor (BCR) is activated upon interaction with its cognate antigen or with anti‐BCR antibodies is not fully understood. We have recently shown that B‐cell activation is accompanied by the opening of the pre‐organized BCR oligomers, an observation that strengthens the role of receptor reorganization in signalling. We have now analysed the BCR oligomer opening and signalling upon treatment with different monovalent stimuli. Our results indicate that monovalent antigens are able to disturb and open the BCR oligomer, but that this requires the presence and activity of the Src family kinase (SFK) Lyn. We have also shown that monovalent Fab fragments of anti‐BCR antibodies can open the BCR oligomers as long as they directly interact with the antigen‐binding site. We found that monovalent antigen binding opens both the IgM‐BCR and IgD‐BCR, but calcium signalling is only seen in cells expressing IgM‐BCR; this provides a molecular basis for IgM‐ and IgD‐BCR functional segregation.
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Affiliation(s)
- Christoph Volkmann
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Naema Brings
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Martin Becker
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Elias Hobeika
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany.,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.,Institute of Immunology University Hospital Ulm, Ulm, Germany
| | - Jianying Yang
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany .,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.,Freiburg Institute for Advanced Studies (FRIAS) University of Freiburg, Freiburg, Germany.,University of Strasbourg Institute for Advanced Study (USIAS) University of Strasbourg, Strasbourg, France
| | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, Department of Molecular Immunology, Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany .,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
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Fiedler HP, Kulik A, Schüz TC, Volkmann C, Zeeck A. Biosynthetic capacities of actinomycetes. 2. Juglomycin Z, a new naphthoquinone antibiotic from Streptomyces tendae. J Antibiot (Tokyo) 1994; 47:1116-22. [PMID: 7961161 DOI: 10.7164/antibiotics.47.1116] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [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: 01/28/2023]
Abstract
A new juglomycin-type antibiotic was identified by a HPLC-diode array screening technique in the culture filtrate of Streptomyces tendae Tü 901/8c. Juglomycin Z (1) differs from all other known juglomycin compounds by an additional methyl group in position 3 of the naphthoquinone ring system. Juglomycin Z is antibiotically active against Gram-positive and Gram-negative bacteria and against yeasts.
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Affiliation(s)
- H P Fiedler
- Biologisches Institut, LB Mikrobiologie/Antibiotika, Universität Tübingen, Germany
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Abraham S, Klein HP, Lin CY, Volkmann C. The effects of space flight on some rat liver enzymes regulating carbohydrate and lipid metabolism. Adv Space Res 1981; 1:199-217. [PMID: 11541711 DOI: 10.1016/0273-1177(81)90263-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have examined, in the livers of rats carried aboard the Cosmos 936 biosatellite, the activities of about 30 enzymes concerned with carbohydrate and lipid metabolism. In addition to the enzyme studies, the levels of glycogen and of the individual fatty acids in hepatic lipids were determined. Livers from flight and ground control rats at recovery (R0) and 25 days after recovery (R25) were used for these analyses. For all parameters measured, the most meaningful comparisons are those made between flight stationary (FS) and flight centrifuged (FC) animals at RQ. When these two groups of flight rats were compared at R0, statistically significant decreases in the activity levels of glycogen phosphorylase, alpha-glycerol phosphate acyl transferase, diglyceride acyl transferase, aconitase and 6-phosphogluconate dehydrogenase and an increase in the palmitoyl CoA desaturase were noted in the weightless group (FS). The significance of these findings was strengthened by the fact that all enzyme activities showing alterations at R0 returned to normal 25 days postflight. When liver glycogen and total fatty acids of the two sets of flight animals were determined, significant differences that could be attributed to reduced gravity were observed. The weightless group (FS) at R0 contained, on the average, more than twice the amount of glycogen than did the centrifuged controls (FC) and a remarkable shift in the ratio of palmitate to palmitoleate was noted. These metabolic alterations, both in enzyme levels and in hepatic constituents, appear to be characteristic of the weightless condition. Our data seem to justify the conclusion that centrifugation during flight is equivalent to terrestrial gravity.
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Affiliation(s)
- S Abraham
- Bruce Lyon Memorial Research Laboratory, Children's Hospital Medical Center, Oakland, CA, USA
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Abraham S, Lin CY, Klein HP, Volkmann C, Tigranyan RA, Vetrova EG. Studies of specific hepatic enzymes involved in the conversion of carbohydrates to lipids in rats exposed to prolonged spaceflight aboard Cosmos 1129. Physiologist 1980; 23:S55-S58. [PMID: 7243938] [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: 05/21/2023]
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Abstract
A crude small particle pellet, obtained from postmitochondrial supernatant fractions of Saccharomyces cerevisiae, contains about half the ergosterol and phospholipid of crude cell homogenates. Most of the phospholipid of this pellet is in a "heavy" fraction which, with the aid of electron microscopy, shows membranous elements in addition to discrete particles. The "heavy" fraction, upon treatment with deoxycholate, can be freed of membranes, or, with ribonuclease treatment, ribosomes can be removed, leaving relatively clean membranes. The "heavy" fraction resembles the microsomes of animal cells, but contains considerably less lipids, including phospholipids, thus suggesting a less well-developed intracellular membrane system.
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