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Goedegebuur J, Abbel D, Accassat S, Achterberg WP, Akbari A, Arfuch VM, Baddeley E, Bax JJ, Becker D, Bergmeijer B, Bertoletti L, Blom JW, Calvetti A, Cannegieter SC, Castro L, Chavannes NH, Coma-Auli N, Couffignal C, Edwards A, Edwards M, Enggaard H, Font C, Gava A, Geersing GJ, Geijteman ECT, Greenley S, Gregory C, Gussekloo J, Hoffmann I, Højen AA, van den Hout WB, Huisman MV, Jacobsen S, Jagosh J, Johnson MJ, Jørgensen L, Juffermans CCM, Kempers EK, Konstantinides S, Kroder AF, Kruip MJHA, Lafaie L, Langendoen JW, Larsen TB, Lifford K, van der Linden YM, Mahé I, Maiorana L, Maraveyas A, Martens ESL, Mayeur D, van Mens TE, Mohr K, Mooijaart SP, Murtagh FEM, Nelson A, Nielsen PB, Ording AG, Ørskov M, Pearson M, Poenou G, Portielje JEA, Raczkiewicz D, Rasmussen K, Trinks-Roerdink E, Schippers I, Seddon K, Sexton K, Sivell S, Skjøth F, Søgaard M, Szmit S, Trompet S, Vassal P, Visser C, van Vliet LM, Wilson E, Klok FA, Noble SIR. Towards optimal use of antithrombotic therapy of people with cancer at the end of life: A research protocol for the development and implementation of the SERENITY shared decision support tool. Thromb Res 2023; 228:54-60. [PMID: 37276718 DOI: 10.1016/j.thromres.2023.05.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/02/2023] [Accepted: 05/05/2023] [Indexed: 06/07/2023]
Abstract
BACKGROUND Even though antithrombotic therapy has probably little or even negative effects on the well-being of people with cancer during their last year of life, deprescribing antithrombotic therapy at the end of life is rare in practice. It is often continued until death, possibly resulting in excess bleeding, an increased disease burden and higher healthcare costs. METHODS The SERENITY consortium comprises researchers and clinicians from eight European countries with specialties in different clinical fields, epidemiology and psychology. SERENITY will use a comprehensive approach combining a realist review, flash mob research, epidemiological studies, and qualitative interviews. The results of these studies will be used in a Delphi process to reach a consensus on the optimal design of the shared decision support tool. Next, the shared decision support tool will be tested in a randomised controlled trial. A targeted implementation and dissemination plan will be developed to enable the use of the SERENITY tool across Europe, as well as its incorporation in clinical guidelines and policies. The entire project is funded by Horizon Europe. RESULTS SERENITY will develop an information-driven shared decision support tool that will facilitate treatment decisions regarding the appropriate use of antithrombotic therapy in people with cancer at the end of life. CONCLUSIONS We aim to develop an intervention that guides the appropriate use of antithrombotic therapy, prevents bleeding complications, and saves healthcare costs. Hopefully, usage of the tool leads to enhanced empowerment and improved quality of life and treatment satisfaction of people with advanced cancer and their care givers.
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Affiliation(s)
- J Goedegebuur
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands; Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands
| | - D Abbel
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands; Department of Medicine - Internal Medicine and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands
| | - S Accassat
- Department of Vascular and Therapeutical Medicine, University Hospital of Saint-Etienne, Saint-Étienne, France
| | - W P Achterberg
- Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, the Netherlands
| | - A Akbari
- Swansea University, Swansea, Wales, United Kingdom
| | - V M Arfuch
- Department of Medical Oncology, Hospital Clinic Barcelona, Clinical Institute of Haematological and Oncological Diseases (ICMHO), IDIBAPS, Barcelona, Spain
| | - E Baddeley
- Cardiff University, Cardiff, United Kingdom
| | - J J Bax
- Department of Medicine - Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | - D Becker
- University Medical Center Mainz, Mainz, Germany
| | | | - L Bertoletti
- Department of Vascular and Therapeutical Medicine, Jean Monnet University, University Hospital of Saint-Étienne, Saint-Étienne, France
| | - J W Blom
- Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, the Netherlands
| | - A Calvetti
- Assistance Publique-Hopitaux de Paris, Paris, France
| | - S C Cannegieter
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands; Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, the Netherlands
| | - L Castro
- Vall d'Hebron Research Institute, Barcelona, Spain
| | - N H Chavannes
- Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, the Netherlands
| | - N Coma-Auli
- Department of Medical Oncology, Hospital Clinic Barcelona, Clinical Institute of Haematological and Oncological Diseases (ICMHO), IDIBAPS, Barcelona, Spain
| | - C Couffignal
- Hôpital Louis Mourier, APHP, Assistance Publique-Hopitaux de Paris, Paris, France
| | - A Edwards
- Cardiff University, Cardiff, United Kingdom
| | - M Edwards
- Cardiff University, Cardiff, United Kingdom
| | - H Enggaard
- Aalborg University Hospital, Aalborg, Denmark
| | - C Font
- Department of Medical Oncology, Hospital Clinic Barcelona, Clinical Institute of Haematological and Oncological Diseases (ICMHO), IDIBAPS, Barcelona, Spain
| | - A Gava
- Societa per l'Assistenza al Malato Oncologico Terminale Onlus (S.A.M.O.T.) Ragusa Onlus, Ragusa, Italy
| | - G J Geersing
- Julius Center for Health Sciences and Primary Care, Department of General Practice, University Medical Center Utrecht, Utrecht, the Netherlands
| | - E C T Geijteman
- Department of Medical Oncology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - S Greenley
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - C Gregory
- Cardiff University, Cardiff, United Kingdom
| | - J Gussekloo
- Department of Medicine - Internal Medicine and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands; Department of Public Health and Primary Care, Leiden University Medical Center, Leiden, the Netherlands
| | - I Hoffmann
- Hôpital Bichat, APHP, Assistance Publique-Hopitaux de Paris, Paris, France
| | - A A Højen
- Aalborg University Hospital, Aalborg, Denmark
| | - W B van den Hout
- Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands
| | - M V Huisman
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands
| | - S Jacobsen
- Aalborg University Hospital, Aalborg, Denmark
| | - J Jagosh
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - M J Johnson
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - L Jørgensen
- Aalborg University Hospital, Aalborg, Denmark
| | - C C M Juffermans
- Centre of Expertise in Palliative Care, Leiden University Medical Center, Leiden, the Netherlands
| | - E K Kempers
- Department of Hematology, Erasmus MC, Erasmus University Medical Center, Rotterdam, the Netherlands
| | | | - A F Kroder
- Todaytomorrow, Rotterdam, the Netherlands
| | - M J H A Kruip
- Department of Hematology, Erasmus MC, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - L Lafaie
- Department of Geriatrics and Gerontology, Jean Monnet University, University Hospital of Saint-Étienne, Saint-Étienne, France
| | | | - T B Larsen
- Aalborg University Hospital, Aalborg, Denmark
| | - K Lifford
- Cardiff University, Cardiff, United Kingdom
| | - Y M van der Linden
- Centre of Expertise in Palliative Care, Leiden University Medical Center, Leiden, the Netherlands; Netherlands Comprehensive Cancer Organization, Utrecht, the Netherlands
| | - I Mahé
- Department of Innovative Therapies in Haemostasis, Hôpital Louis Mourier, APHP, Paris, France
| | - L Maiorana
- Societa per l'Assistenza al Malato Oncologico Terminale Onlus (S.A.M.O.T.) Ragusa Onlus, Ragusa, Italy
| | - A Maraveyas
- Clinical Sciences Centre Hull York Medical School University of Hull, Hull, United Kingdom
| | - E S L Martens
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands
| | - D Mayeur
- Centre Georges-François Leclerc, Dijon, France
| | - T E van Mens
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands
| | - K Mohr
- University Medical Center Mainz, Mainz, Germany
| | - S P Mooijaart
- Department of Medicine - Internal Medicine and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands
| | - F E M Murtagh
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - A Nelson
- Cardiff University, Cardiff, United Kingdom
| | - P B Nielsen
- Aalborg University Hospital, Aalborg, Denmark
| | - A G Ording
- Aalborg University Hospital, Aalborg, Denmark
| | - M Ørskov
- Aalborg University Hospital, Aalborg, Denmark
| | - M Pearson
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - G Poenou
- Department of Vascular and Therapeutical Medicine, Jean Monnet University, University Hospital of Saint-Étienne, Saint-Étienne, France
| | - J E A Portielje
- Department of Medicine - Internal medicine and Medical Oncology, Leiden University Medical Center, Leiden, the Netherlands
| | - D Raczkiewicz
- Department of Medical Statistics, School of Public Health, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - K Rasmussen
- Aalborg University Hospital, Aalborg, Denmark
| | - E Trinks-Roerdink
- Julius Center for Health Sciences and Primary Care, Department of General Practice, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - K Seddon
- Wales Cancer Research Centre, Cardiff, UK
| | - K Sexton
- Cardiff University, Cardiff, United Kingdom
| | - S Sivell
- Cardiff University, Cardiff, United Kingdom
| | - F Skjøth
- Aalborg University Hospital, Aalborg, Denmark
| | - M Søgaard
- Aalborg University Hospital, Aalborg, Denmark
| | - S Szmit
- Department of Cardio-Oncology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - S Trompet
- Department of Medicine - Internal Medicine and Geriatrics, Leiden University Medical Center, Leiden, the Netherlands
| | - P Vassal
- Department of Vascular and Therapeutical Medicine, University Hospital of Saint-Etienne, Saint-Étienne, France
| | - C Visser
- Department of Hematology, Erasmus MC, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - L M van Vliet
- Department of Health, Medicine and Neuropsychology, Leiden University, Leiden, the Netherlands
| | - E Wilson
- Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, Hull, United Kingdom
| | - F A Klok
- Department of Medicine - Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, the Netherlands.
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Morsbach S, García-Bardon A, Kamuf J, Müller B, Beghersa N, Mohr K, Landfester K. Quantification of fluorescent dyes in organ tissue samples via HPLC analysis. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1072:34-39. [PMID: 29132023 DOI: 10.1016/j.jchromb.2017.11.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 05/31/2017] [Revised: 11/07/2017] [Accepted: 11/08/2017] [Indexed: 10/18/2022]
Abstract
The determination of regional blood flow via the accumulation of fluorescent microspheres is a concept regularly used in medical research. Typically, the microbeads get extracted from the tissue of interest and are then quantified by measuring the absorption or fluorescence of the incorporated dyes without further separation from the medium. However, in that case the absorption spectra of different dyes can overlap when used simultaneously, leading to an overestimation of the concentration. Additionally, background absorption from the medium can be problematic. Therefore, a high performance liquid chromatography method for the simultaneous detection of four dyes (orange, crimson, yellow-green and red) incorporated in different microbeads in samples from biological media such as organ tissue (brain, heart and kidneys) was developed. Since for biological samples often a large sample size is required for sufficient statistics, the method was optimized to yield very short run times. With this method it was possible to detect very low concentrations of only one microsphere per gram of organ tissue. By applying this sensitive quantification technique, it was demonstrated that the application of microbeads for perfusion measurements might not be reliable due to different organ distributions in each animal.
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Affiliation(s)
- S Morsbach
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128 Germany.
| | - A García-Bardon
- Department of Anesthesiology, Medical Center of the Johannes Gutenberg University, Langenbeckstraße 1, Mainz, 55131 Germany
| | - J Kamuf
- Department of Anesthesiology, Medical Center of the Johannes Gutenberg University, Langenbeckstraße 1, Mainz, 55131 Germany
| | - B Müller
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128 Germany
| | - N Beghersa
- Department of Anesthesiology, Medical Center of the Johannes Gutenberg University, Langenbeckstraße 1, Mainz, 55131 Germany
| | - K Mohr
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128 Germany
| | - K Landfester
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128 Germany
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Müller LK, Simon J, Schöttler S, Landfester K, Mailänder V, Mohr K. Pre-coating with protein fractions inhibits nano-carrier aggregation in human blood plasma. RSC Adv 2016. [DOI: 10.1039/c6ra17028e] [Citation(s) in RCA: 29] [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: 01/21/2023] Open
Abstract
The change of a nanoparticles' physicochemical properties after incubation with defined protein fractions or whole human plasma was utilized for tailoring its properties regarding stability against aggregation and cellular response.
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Affiliation(s)
- L. K. Müller
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - J. Simon
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - S. Schöttler
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Dermatology Clinic
- University Medical Center Mainz
| | - K. Landfester
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - V. Mailänder
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Dermatology Clinic
- University Medical Center Mainz
| | - K. Mohr
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
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Schrage R, De Min A, Hochheiser K, Kostenis E, Mohr K. Superagonism at G protein-coupled receptors and beyond. Br J Pharmacol 2015; 173:3018-27. [PMID: 26276510 DOI: 10.1111/bph.13278] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/01/2015] [Accepted: 08/08/2015] [Indexed: 12/18/2022] Open
Abstract
Ligands targeting GPCRs can be categorized according to their intrinsic efficacy to trigger a specific, receptor-mediated response. A ligand endowed with the same level of efficacy as the endogenous agonist can be classified as a full agonist, whereas a compound that displays greater efficacy, that is, higher receptor signalling output than the endogenous agonist, can be called a superagonist. Subsequent to GPCR activation, an intracellular signalling cascade is set in motion, which may generate substantial amplification of the signal. This may obscure superagonism in pharmacological assays and, therefore, the definition of superagonism necessitates a combination of operational approaches, reduction of spare receptors or estimation of receptor activation close to the receptor level to quantify relative agonist efficacies in a particular system. The first part of this review will compare GPCR superagonism with superagonism in the field of immunology, where this term is well established. In the second part, known GPCR superagonists will be reviewed. Then, the experimental and analytical challenges in the deconvolution of GPCR superagonism will be addressed. Finally, the potential benefit of superagonism is discussed. The molecular mechanisms behind GPCR superagonism are not completely understood. However, crystallography shows that agonist binding alone is not sufficient for a fully active receptor state and that binding of the G protein is at least equally important. Accordingly, the emerging number of reported superagonists implies that ligand-induced receptor conformations more active than the ones stabilized by the endogenous agonist are indeed feasible. Superagonists may have therapeutic potential when receptor function is impaired or to induce negative feedback mechanisms. Linked Articles This article is part of a themed section on Molecular Pharmacology of G Protein-Coupled Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.20/issuetoc.
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Affiliation(s)
- R Schrage
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany.
| | - A De Min
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany
| | - K Hochheiser
- Peter Doherty Institute, Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, 3100, Australia
| | - E Kostenis
- Molecular-, Cellular-, and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, 53115, Bonn, Germany
| | - K Mohr
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany
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Sanker P, Richard KE, Firsching R, Mohr K, Wallenfang T. Tumors of the Craniocervical Junction in Infancy: Particularities of Diagnosis and Management. Skull Base Surg 2015. [DOI: 10.1159/000429775] [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: 11/19/2022]
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Winzen S, Schoettler S, Baier G, Rosenauer C, Mailaender V, Landfester K, Mohr K. Complementary analysis of the hard and soft protein corona: sample preparation critically effects corona composition. Nanoscale 2015; 7:2992-3001. [PMID: 25599336 DOI: 10.1039/c4nr05982d] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Here we demonstrate how a complementary analysis of nanocapsule-protein interactions with and without application media allows gaining insights into the so called hard and soft protein corona. We have investigated how both human plasma and individual proteins (human serum albumin (HSA), apolipoprotein A-I (ApoA-I)) adsorb and interact with hydroxyethyl starch (HES) nanocapsules possessing different functionalities. To analyse the hard protein corona we used sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and a protein quantitation assay. No significant differences were observed with regards to the hard protein corona. For analysis of the soft protein corona we characterized the nanocapsule-protein interaction with isothermal titration calorimetry (ITC) and dynamic light scattering (DLS). DLS and ITC measurements revealed that a high amount of plasma proteins were adsorbed onto the capsules' surface. Although HSA was not detected in the hard protein corona, ITC measurements indicated the adsorption of an HSA amount similar to plasma with a low binding affinity and reaction heat. In contrast, only small amounts of ApoA-I protein adsorb to the capsules with high binding affinities. Through a comparison of these methods we have identified ApoA-I to be a component of the hard protein corona and HSA as a component of the soft corona. We demonstrate a pronounced difference in the protein corona observed depending on the type of characterization technique applied. As the biological identity of a particle is given by the protein corona it is crucial to use complementary characterization techniques to analyse different aspects of the protein corona.
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Affiliation(s)
- S Winzen
- Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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Schrage R, Seemann WK, Klöckner J, Dallanoce C, Racké K, Kostenis E, De Amici M, Holzgrabe U, Mohr K. Agonists with supraphysiological efficacy at the muscarinic M2 ACh receptor. Br J Pharmacol 2014; 169:357-70. [PMID: 23062057 DOI: 10.1111/bph.12003] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/18/2012] [Accepted: 09/19/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Artificial agonists may have higher efficacy for receptor activation than the physiological agonist. Until now, such 'superagonism' has rarely been reported for GPCRs. Iperoxo is an extremely potent muscarinic receptor agonist. We hypothesized that iperoxo is a 'superagonist'. EXPERIMENTAL APPROACH Signalling of iperoxo and newly synthesized structural analogues was compared with that of ACh at label-free M2 muscarinic receptors applying whole cell dynamic mass redistribution, measurement of G-protein activation, evaluation of cell surface agonist binding and computation of operational efficacies. KEY RESULTS In CHO-hM2 cells, iperoxo significantly exceeds ACh in Gi /Gs signalling competence. In the orthosteric loss-of-function mutant M2 -Y104(3.33) A, the maximum effect of iperoxo is hardly compromised in contrast to ACh. 'Superagonism' is preserved in the physiological cellular context of MRC-5 human lung fibroblasts. Structure-signalling relationships including iperoxo derivatives with either modified positively charged head group or altered tail suggest that 'superagonism' of iperoxo is mechanistically based on parallel activation of the receptor protein via two orthosteric interaction points. CONCLUSION AND IMPLICATIONS Supraphysiological agonist efficacy at muscarinic M2 ACh receptors is demonstrated for the first time. In addition, a possible underlying molecular mechanism of GPCR 'superagonism' is provided. We suggest that iperoxo-like orthosteric GPCR activation is a new avenue towards a novel class of receptor activators.
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Affiliation(s)
- R Schrage
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, Bonn, Germany
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Dierking I, Gießelmann F, Zugenmaier P, Mohr K, Zaschke H, Kuczynski W. The Origin of the Helical Twist Inversion in Single Component Cholesteric Liquid Crystals. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/zna-1994-1116] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The cholesteric twist inversion by temperature variation o f a single component thermotropic liquid crystalline system was experimentally investigated and is explained by the partial twisting power model, evaluating the temperature dependent pitch o f five different configurations of a benzoic acid biphenyl ester with two chiral centers. The temperature dependence o f the twisting power and the cholesteric pitch for several stereoisomeric compounds can in first approximation be predicted by the partial twisting powers of the individual chiral centers determined from the partially racemic configurations.
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Affiliation(s)
- I. Dierking
- Institut für Physikalische Chemie der TU Clausthal, Arnold-Sommerfeld-Straße 4, D-38678 Clausthal-Zellerfeld
| | - F. Gießelmann
- Institut für Organische Chemie, Martin-Luther-Universität Halle, Weinbergweg 16, D-06120 Halle
| | - P. Zugenmaier
- Institut für Physikalische Chemie der TU Clausthal, Arnold-Sommerfeld-Straße 4, D-38678 Clausthal-Zellerfeld
| | - K. Mohr
- Institut für Organische Chemie, Martin-Luther-Universität Halle, Weinbergweg 16, D-06120 Halle
| | - H. Zaschke
- Institut für Organische Chemie, Martin-Luther-Universität Halle, Weinbergweg 16, D-06120 Halle
| | - W. Kuczynski
- Institute of Molecular Physics, Polish Academy of Science, Smoluchowskiego 17/19 PL-60-179 Poznan, Poland
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Ahmedat AS, Warnken M, Seemann WK, Mohr K, Kostenis E, Juergens UR, Racké K. Pro-fibrotic processes in human lung fibroblasts are driven by an autocrine/paracrine endothelinergic system. Br J Pharmacol 2013; 168:471-87. [PMID: 22935082 DOI: 10.1111/j.1476-5381.2012.02190.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 07/27/2012] [Accepted: 08/08/2012] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Since endothelin (ET) may act as pro-fibrotic mediator, expression and release of ET isoforms, their receptors and potential pro-fibrotic ET effects were studied in human lung fibroblasts. EXPERIMENTAL APPROACH MRC-5 and primary human lung fibroblasts (phLFb) were cultured. Expression of prepro-ET isoforms was determined by qPCR and release of ET-1 by elisa. ET receptor function was analysed by real-time measurement of dynamic mass redistribution (DMR). Incorporation of [(3) H]-thymidine was determined as measure of proliferation and that of [(3) H]-proline for collagen synthesis. Phospho-p42/44 MAP kinase was determined by Western blot. KEY RESULTS ET-1 is the predominant ET in human lung fibroblasts (hLF), and TGF-β caused a further, selective and sustained up-regulation of ET-1 resulting in increased extracellular ET-1 accumulation. hLFb express mRNA encoding ET-A and ET-B receptors. Expression of both receptors was confirmed at protein level. ET-1 induced marked DMR signals, an effect that involved ET-A and ET-B receptors. Stimulatory effects of ET-1 on hLFb proliferation and collagen synthesis were mediated exclusively via ET-A receptors. ET-1, again via ET-A receptors, induced rapid activation of ERK MAPK, shown to be a crucial cellular signal in ET-1-induced collagen synthesis. ET-1-induced activation of ERK and collagen synthesis was, in contrast to corresponding effect of a muscarinic agonist, largely insensitive to pertussis toxin. CONCLUSIONS AND IMPLICATIONS hLFb are endowed with all elements necessary to build a functional autocrine/paracrine endothelinergic system, which appears to drive pro-fibrotic airway and lung remodelling processes, effects for which only ET-A, but not ET-B receptors appear to be of significance.
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Affiliation(s)
- A S Ahmedat
- Institute of Pharmacology & Toxicology, University of Bonn, Bonn, Germany
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Lamyel F, Warnken-Uhlich M, Seemann WK, Mohr K, Kostenis E, Ahmedat AS, Smit M, Gosens R, Meurs H, Miller-Larsson A, Racké K. The β2-subtype of adrenoceptors mediates inhibition of pro-fibrotic events in human lung fibroblasts. Naunyn Schmiedebergs Arch Pharmacol 2011; 384:133-45. [PMID: 21603974 DOI: 10.1007/s00210-011-0655-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/09/2011] [Indexed: 01/10/2023]
Abstract
Fibrosis is part of airway remodelling observed in bronchial asthma and COPD. Pro-fibrotic activity of lung fibroblasts may be suppressed by β-adrenoceptor activation. We aimed, first, to characterise the expression pattern of β-adrenoceptor subtypes in human lung fibroblasts and, second, to probe β-adrenoceptor signalling with an emphasis on anti-fibrotic actions. Using reverse transcription PCR, messenger RNA (mRNA) encoding β(2)-adrenoceptors was detected in MRC-5, HEL-299 and primary human lung fibroblasts, whereas transcripts for β(1)- and β(3)-adrenoceptors were not found. Real-time measurement of dynamic mass redistribution in MRC-5 cells revealed β-agonist-induced G(s)-signalling. Proliferation of MRC-5 cells (determined by [(3)H]-thymidine incorporation) was significantly inhibited by β-agonists including the β(2)-selective agonist formoterol (-logIC(50), 10.2) and olodaterol (-logIC(50), 10.6). Formoterol's effect was insensitive to β(1)-antagonism (GCP 20712, 3 μM), but sensitive to β(2)-antagonism (ICI 118,551; apparent, pA (2), 9.6). Collagen synthesis in MRC-5 cells (determined by [(3)H]-proline incorporation) was inhibited by β-agonists including formoterol (-logIC(50), 10.0) and olodaterol (-logIC(50), 10.3) in a β(2)-blocker-sensitive manner. α-Smooth muscle actin, a marker of myo-fibroblast differentiation, was down-regulated at the mRNA and the protein level by about 50% following 24 and 48 h exposure to 1 nM formoterol, a maximally active concentration. In conclusion, human lung fibroblasts exclusively express β(2)-adrenoceptors and these mediate inhibition of various markers of pro-fibrotic cellular activity. Under clinical conditions, anti-fibrotic actions may accompany the therapeutic effect of long-term β(2)-agonist treatment of bronchial asthma and COPD.
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Affiliation(s)
- F Lamyel
- Institute of Pharmacology & Toxicology, University of Bonn, Bonn, Germany
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Thudium F, Mohr K, Schindler O, Reichstein T. Die Glykoside von Acokanthera Schimperi (A. DC.) Benth. et Hook. 2. Mitteilung. Untersuchung des Wurzel- und Zweig-Holzes der Form, die von den Wa-Giriama zur Pfeilgiftbereitung verwendet wird. Glykoside und Aglykone, 189. Mitteilung. Helv Chim Acta 2010. [DOI: 10.1002/hlca.660410303] [Citation(s) in RCA: 6] [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: 11/09/2022]
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Schuren J, Mohr K. Pascal's law and the dynamics of compression therapy: a study on healthy volunteers. INT ANGIOL 2010; 29:431-435. [PMID: 20924347] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
AIM The aim of this paper was to determine whether Pascal's law can be used to explain the dynamics of compression therapy. METHODS Sub-bandage pressures were recorded at three different levels to investigate the transmission of applied pressure on the legs of 12 healthy volunteers and 216 applications. RESULTS The experimental model revealed that when pressure is increased at a certain area in a compressed leg, the pressure is transmitted within the compressed area. CONCLUSION The dynamics of effective compression therapy are explained by Pascal's Law, which states that when pressure is applied on a fluid (a muscle or muscle group) in a closed container (fascia muscularis and compression bandage), there is an equal increase at every other point in the container.
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Affiliation(s)
- J Schuren
- 3M Deutschland GmbH, Infection Prevention and Skin and Wound Laboratory, Neuss, Germany.
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Mohr K, Ruschke K, Große R, Strauss HG, Holzhausen HJ, Spielmann RP, Hauptmann S, Thomssen C. Neoadjuvante Chemotherapie mit FEC und Paclitaxel±Trastuzumab beim lokal fortgeschrittenen Mammakarzinom. Geburtshilfe Frauenheilkd 2009. [DOI: 10.1055/s-0029-1238990] [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: 10/20/2022] Open
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Appenroth D, Decker M, Tränkle C, Mohr K, Lehmann J, Fleck C. In vivo investigations on the cholinesterase-inhibiting effects of tricyclic quinazolinimines: Scopolamine-induced cognitive impairments in rats are attenuated at low dosage and reinforced at higher dosage. Pflugers Arch 2007; 455:895-901. [PMID: 17717685 DOI: 10.1007/s00424-007-0325-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 05/18/2007] [Accepted: 07/09/2007] [Indexed: 10/22/2022]
Abstract
Tricyclic quinazolinimines as a novel class of potent inhibitors of cholinesterases in vitro are micro- and sub-micromolar inhibitors with activities at both acetyl- (AChE) and butyrylcholinesterase (BChE) or at BChE only. To further establish the antiamnesic properties of this class of compounds, an in vivo test system has been established. Cognitive impairment in rats was reversibly induced by scopolamine (0.05 mg/100 g body weight) and evaluated in an eight-arm radial maze. A representative quinazolinimine (MD212) showed attenuation of cognitive deficits at a low dosage (0.01 mg/100 g body weight), whereas at a high dosage (>0.1 mg/100 g body weight) the effect of scopolamine is markedly reinforced. As MD212 applied alone does not influence rat's cognition at all, the reinforcement of scopolamine effect has to be due to the amplification of scopolamine action possibly by (1) inhibition of scopolamine metabolism, (2) influence of scopolamine on MD212 metabolism or (3) allosteric modulation of mACh receptors. Receptor-binding studies proved hypothesis (3): MD212 stabilizes [3H]N-methylscopolamine binding to muscarinic receptors allosterically.
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Affiliation(s)
- D Appenroth
- Institute of Pharmacology and Toxicology, Friedrich Schiller University Jena, Jena, Germany
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Holzgrabe U, Schubert-Zsilavecz M, Mohr K, Dingermann T. [Scientific pharmacy and homeopathy]. Pharm Unserer Zeit 2006; 35:5. [PMID: 16465858 DOI: 10.1002/pauz.200690007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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Abstract
BACKGROUND While performing microsurgical disc excision, usually the sequestrated disc fragments as well as loosened or degenerated parts of the nucleus pulposus are removed. It is controversial whether this strategy is always necessary. The aim of this study was to examine this question based on clinical results. MATERIAL AND METHODS Prospectively all relevant data from 149 consecutive patients after sequestrectomy were collected including the clinical course of the patients with a mean follow-up of 2.3 years. A detailed analysis of the actual pain status, the functional capacity and possible additional spinal operations was performed. RESULTS During early follow-up, there was one superficial wound infection, which was treated conservatively. The success rate, as measured by patient self-assessment, was 62% for excellent and good and 25% for fair results; 13% of the patients treated declared a poor result having no benefits from surgery. The average FFbH score during follow-up was 74% (100% means no functional restriction). Radicular pain and low back pain had the same intensity on the average, in contrast to some other investigations, where low back pain was lower than radicular pain [14]. Of the 149 patients, 4 underwent a second spine surgery at the same level, 2 of which were recurrent disc herniations (=1.3%). CONCLUSION Simple fragment excision revealed similar results compared to standard microdiscectomy. There was an especially low number of recurrences in contrast to former reports [16]. This was probably caused by the conscientious selection of patients for sequestrectomy according to well-defined criteria. Whether simple sequestrectomy can effectively treat an additional low back pain component must be clarified by further prospective studies.
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Affiliation(s)
- E Kast
- Neurochirurgische Abteilung, Kantonsspital, Brauerstrasse 15, CH-8401 Winterthur, Switzerland.
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Kast E, Mohr K, Richter HP, Börm W. Complications of transpedicular screw fixation in the cervical spine. Eur Spine J 2005; 15:327-34. [PMID: 15912352 PMCID: PMC3489301 DOI: 10.1007/s00586-004-0861-7] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Revised: 11/10/2004] [Accepted: 11/26/2004] [Indexed: 10/25/2022]
Abstract
Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1 mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons.
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Affiliation(s)
- E Kast
- Neurosurgical Department, Kantonsspital Winterthur, Brauerstr. 15, Winterthur, 8401, Switzerland.
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Weissflog W, Möckel P, Kolbe A, Kresse H, Pelzl G, Mohr K, Zaschke H. Synthese und Eigenschaften kristallin-flüssiger Derivate des Rhodanins. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/prac.19843260314] [Citation(s) in RCA: 4] [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: 11/06/2022]
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v. Euw J, Gürtler J, Lardon A, Mohr K, Reber F, Richter R, Schindler O, Reichstein T. Die Glykoside vonStrophanthus sarmentosus P. DC. 8. Mitteilung. Untersuchung von Einzelpflanzen der „Sarmentogenin-produzierenden Variante b”︁Strophanthus sarmentosus var. senegambiae (A. DC.) Monachino. Glykoside und Aglykone, 183. Mitteilung. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19570400710] [Citation(s) in RCA: 7] [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: 11/08/2022]
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Mohr K, Thudium F, Schindler O, Reichstein T. Die Glykoside der Samen vonAcokanthera schimperi (A. DC.) Bentham & Hooker. 1. Mitteilung. Untersuchung der Pflanzen aus Erythräa. Glykoside und Aglykone, 185. Mitteilung. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19570400720] [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: 11/11/2022]
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Barton DHR, Mohr K, Reichstein T, Schindler O. Identifizierung von Substanz Nr. 752 mit Echinocystsäure. Glykoside und Aglykone, 160. Mitteilung. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19560390209] [Citation(s) in RCA: 8] [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: 11/11/2022]
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v. Euk J, Mohr K, Schindler O, Reichstein T. Die Glykoside der Samen von Strophanthus sarmentosus var. majorDewèvre. Die Glykoside der Samen von Strophanthus sarmentosus A. P. DC., 7. Mitteilung. Glykoside und Aglykone, 158. Mitteilung. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19560390137] [Citation(s) in RCA: 8] [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: 11/09/2022]
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Mohr K, Tränkle C, Holzgrabe U. Structure/activity relationships of M2 muscarinic allosteric modulators. Recept Channels 2004; 9:229-40. [PMID: 12893536] [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] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Allosteric modulation of G protein-coupled receptors has been intensively studied at muscarinic acetylcholine receptors. Findings made with archetypal allosteric agents such as gallamine, alcuronium, and bis(ammonio)alkane-type agents revealed that binding of orthosteric ligands that attach to the acetylcholine site can be allosterically decreased or increased or left unaltered in a subtype-selective fashion. Analyses of structure/activity relationships (SARs) help to elucidate the molecular events underlying the allosteric action and they may pilot the development of new allosteric agents with improved properties and therapeutic perspectives. With a focus on SARs, this review illustrates the principles of muscarinic allosteric interactions, gives an overview of SARs in congeners of archetypal allosteric agents, and considers the topology of M(2) muscarinic allosteric interactions that are characterized by divergent binding modes.
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Affiliation(s)
- K Mohr
- Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Bonn, Germany.
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Abstract
The residues derived from the uptake of fumonisin B1, a toxic metabolite of Fusarium verticillioides frequently occurring in corn and corn products, were determined in growing pigs. After oral administration of 100 mg FB(1)/animal/day for 5-11 days, serum, bile, lung, liver, kidney, brain, spleen, pancreas, heart, muscle, eye, and fat samples were collected immediately and analysed by LC-MS. The highest values were measured in kidney (833 +/- 1329 microg kg(-1), mean +/- SD), liver (231 +/- 163 microg kg(-1)), lung (170 +/- 311 microg kg(-1)) and spleen (854 +/- 2212 microg kg(-1)). Muscle contained 26 +/- 41 microg kg(-1), while in fat only 2 +/- 3 microg kg(-1) were traceable. Despite the potential accumulation over extended feeding periods as well as the large variations in the residue formation of FB(1), a carry-over in edible tissues from swine was considered not to be of toxicological relevance.
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Affiliation(s)
- K Meyer
- Technische Universität München, Institute of Animal Hygiene, Freising, Germany.
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Zlotos DP, Buller S, Holzgrabe U, Mohr K. Bisquaternary dimers of strychnine and brucine. A new class of potent enhancers of antagonist binding to muscarinic M2 receptors. Bioorg Med Chem 2003; 11:2627-34. [PMID: 12757728 DOI: 10.1016/s0968-0896(03)00146-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [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: 11/21/2022]
Abstract
Bisquaternary dimers of strychnine and brucine were synthesized and their allosteric effect on muscarinic acetylcholine M(2) receptors was examined. The compounds retarded the dissociation of the antagonist [(3)H]N-methylscopolamine ([(3)H]NMS) from porcine cardiac cholinoceptors. This action indicated ternary complex formation. All compounds exhibited higher affinity to the allosteric site of [(3)H]NMS-occupied M(2) receptors than the monomeric strychnine and brucine, while the positive cooperativity with NMS was fully maintained. SAR studies revealed the unchanged strychnine ring as an important structural feature for high allosteric potency.
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Affiliation(s)
- D P Zlotos
- Pharmaceutical Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
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Antoniadis G, König RW, Mohr K, Kretschmer T, Richter HP. [Management of obstetrical brachial plexus palsy--own experience with the primary operative technique]. HANDCHIR MIKROCHIR P 2003; 35:98-105. [PMID: 12874720 DOI: 10.1055/s-2003-40773] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [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: 10/27/2022] Open
Abstract
Obstetrical brachial plexus palsy occurs at a frequency of 0.6 to 2.5 per 1000 births. 80 to 95% of these lesions recover spontaneously. If spontaneous recovery does not occur within the first six months of life, investigations like electrophysiology, and CT-myelography and surgical exploration of the brachial plexus are recommended. During the last ten years 73 children with obstetrical brachial plexus lesions were examined in our department. 29 newborns underwent surgery on the brachial plexus. In 20 out of 29 children nerve root avulsions were diagnosed preoperatively. We performed in 16 cases nerve grafting after neuroma excision, in four cases nerve grafting combined with neurotization, in seven cases external or internal neurolysis, and in the remaining two cases neurotization and plexo-plexal transfer, respectively. The children were followed up between 18 and 50 months (range 27 months) in 18 cases. Elbow function according to Gilbert scale achieved one half of the patients four to five points and the other half two to three points. We found shoulder function with abduction between 45 degrees to 128 degrees and external rotation in 61% (Grade II to V, according to Gilbert scale). In 31% hand function showed Grade III and IV (Gilbert and Raimondi scale). We recommend decision for surgery at the age of six months. Operation should be planned between six to nine months of life. In addition, physical therapy and options including muscle transfers and orthopaedic procedures must be available to ensure the optimal outcome for these children.
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Affiliation(s)
- G Antoniadis
- Neurochirurgische Klinik, Universität Ulm/Günzburg, Bezirkskrankenhaus Günzburg.
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Klein CD, Tabeteh GF, Laguna AV, Holzgrabe U, Mohr K. Lipophilicity and membrane interactions of cationic-amphiphilic compounds: syntheses and structure-property relationships. Eur J Pharm Sci 2001; 14:167-75. [PMID: 11500262 DOI: 10.1016/s0928-0987(01)00170-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [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: 11/22/2022]
Abstract
This study was performed to elucidate the relationship between steric factors, lipophilicity, and the potency of cationic-amphiphilic compounds to displace calcium ions from phosphatidylserine monolayers. The latter property is considered to be a substance/phospholipid affinity measure. A series of cationic-amphiphilic 3-phenyl-N,N-dimethylpropylamine derivatives with systematic structural variations was synthesized. Lipophilicity values were determined by chromatographic (RP-HPLC, log D(7.4)), shake-flask (log P), and theoretical (CLOGP) techniques. The potency of the compounds to displace calcium ions from phosphatidylserine monolayers was determined using a radiotracer technique, employing the isotope (45)Ca(2+). The experimental lipophilicity values of several isomeric biphenyl- and diphenyl-congeners differ more than could be expected from the CLOGP-calculations and show a good correlation to the calculated molecular surface areas. Although the affinity of the substances to the phospholipid monolayer tends to increase with lipophilicity, no general interrelation between the two properties could be found. Surprisingly, the assay system (a phospholipid monolayer) was quite sensitive towards small steric changes at the 'ligand' molecules. Stereochemical factors have a considerable influence on the interaction of solutes with phospholipid membranes. It must be questioned whether lipophilicity measures alone, without taking other molecular features into account, can meaningfully be used to explain or predict the influence of solutes on membrane-related processes and properties.
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Affiliation(s)
- C D Klein
- Pharmaceutical Chemistry, ETH Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland.
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Tränkle C, Kostenis E, Mohr K. Muscarinic allosteric modulation: M2/M3 subtype selectivity of gallamine is independent of G-protein coupling specificity. Naunyn Schmiedebergs Arch Pharmacol 2001; 364:172-8. [PMID: 11534857 DOI: 10.1007/s002100100441] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Among the five subtypes of muscarinic acetylcholine receptors, the sensitivity towards allosteric modulation is generally higher in M2 and M4 receptors that preferentially couple to inhibitory G-proteins of the Gi/o type than in M1, M3, and M5 that preferentially couple to stimulatory G-proteins such as Gq/11. We aimed to check whether the high allosteric sensitivity of the M2 receptor compared to M3 is related to the differential G-protein coupling preference. As the third intracellular loop (i3) is known to be the major determinant in receptor G-protein coupling specificity, we used wild-type M2 and M3 receptors and the related chimeric constructs with exchanged i3-loops, i.e., M2 containing M3-i3 (M2/M3-i3) and M3 containing M2-i3 (M3/M2-i3). The allosteric effect of the archetypal modulator gallamine on the dissociation and the equilibrium binding of [3H]N-methylscopolamine ([3H]NMS) was measured in membranes of mouse A9L cells stably expressing the wild-type and the chimeric receptors (4 mM Na2HPO4, 1 mM KH2PO4, pH 7.4, 23 degrees C). The dissociation of [3H]NMS was monophasic under all conditions studied. Control values of t 1/2 were (means +/- SEM, n = 4-7): M2: 3.8 +/- 0.2 min, M2/M3-i3: 4.8 +/- 0.3 min, M3:43.3 +/- 4.2 min, M3/M2-i3: 41.1 +/- 3.6 min. At M2 receptors, 0.2 microM gallamine allosterically reduced the apparent rate constant of dissociation k-1 to 51 +/- 5% of the control value (n = 5). At M2/M3-i3 the allosteric potency of gallamine was not significantly changed (0.2 microM gallamine --> k-1 = 61 +/- 4%, n = 7). At M3, a 20-fold higher concentration was required for an equieffective allosteric action (10 microM gallamine --> k-1 = 51 +/- 5%, n = 5). The potency of gallamine at M3/M2-i3 was not increased compared with M3 receptors (10 microM gallamine --> k-1 = 73 +/- 2%, n = 4) but even significantly diminished. [3H]NMS equilibrium binding experiments revealed that neither the binding constants of gallamine at free receptor subtypes (pKA,M2: 7.57 +/- 0.04, n = 4; pKA,M3: 5.56 +/- 0.13, n = 3) nor the factors of negative cooperativity with [3H]NMS (alphaM2 = 31 +/- 1, alphaM3 = 3 +/- 0.4) were affected by the exchanged i3-loops (pKA,M2/M3-i3: 7.65 +/- 0.03, pKA,M3/M2-i2: 5.35 +/- 0.24, alphaM2/M3-i3= 30 +/- 2, alphaM3/M2-i2 = 3 +/- 0.7). In conclusion, the different sensitivities of M2 and M3 receptors towards allosteric modulation by gallamine are not related to the G-protein coupling specificity of the receptors.
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Affiliation(s)
- C Tränkle
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Germany.
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Abstract
Alkane-bisammonium compounds carrying lateral phthalimido substituents are known to have a high affinity for the allosteric binding site of the acetylcholine M2 receptor. The purpose of this study was to replace the lateral phthalimido moieties with rigid tricyclic skeletons of a large volume in order to learn more about the function of the lateral heterocycles. In addition, methyl groups were introduced into the lateral connecting chains. Allosteric inhibition of the dissociation of [3H]N-methylscopolamine from the M2 receptors in porcine cardiac homogenates served to indicate binding of the test compounds to the allosteric site. The phthalimido groups could be replaced with dibenzazepine moieties without any loss in potency. Interestingly, the additional methyl group in the lateral spacer seems to have a significant influence on the allosteric behaviour.
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Affiliation(s)
- R Li
- Department of Organic Chemistry, School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083, P.R. China
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Schröter A, Tränkle C, Mohr K. Modes of allosteric interactions with free and [3H]N-methylscopolamine-occupied muscarinic M2 receptors as deduced from buffer-dependent potency shifts. Naunyn Schmiedebergs Arch Pharmacol 2000; 362:512-9. [PMID: 11138843 DOI: 10.1007/s002100000316] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Muscarinic M2 acetylcholine receptors contain an allosteric site that is probably located at the entrance of the ligand binding pocket above the orthosteric binding site. With the orthosteric area not occupied, allosteric agents might gain access to this site. The interaction of allosteric agents with orthoster-occupied receptors is known to depend on the buffer conditions in an alloster-specific fashion. Utilizing the buffer-dependent potency shift as an indicator, we aimed to find out for two rod-like shaped and flexible allosteric agents whether or not there is evidence for a switch in the site of attachment in free compared with [3H]N-methylscopolamine ([3H]NMS)-occupied porcine heart M2 receptors. These agents are the bispyridinium compounds WDuo3 (1,3-bis[4-(phthalimidomethoxyimino-methyl)-pyridinium-1-yl] propane dibromide) and Duo3 (4,4'-bis-[(2,6-dichloro-benzyloxy-imino)-methyl]-1,1'-propane-1,3-diyl-bis-pyridinium dibromide). The prototype allosteric agents gallamine and alcuronium were included. Inhibition of [3H]NMS association was taken to reflect alloster interaction with free receptors, inhibition of [3H]NMS dissociation indicated binding to [3H]NMS-occupied receptors. In Na,K,Pi buffer (4 mM Na2HPO4, 1 mM KH2PO4, pH 7.4 at 23 degrees C) compared with Mg,Tris,Cl,Pi buffer (45 mM Tris-HCl, 2.6 mM MgHPO4, pH 7.3 at 37 degrees C) WDuo3 underwent the same loss of potency for the interaction with either free or [3H]NMS-liganded receptors. The loss of potency was quantified by a potency ratio (PR), i.e. the ratio between the concentrations of the modulator leading to a half-maximal delay of [3H]NMS association or dissociation, respectively, in Mg,Tris,Cl,Pi compared with Na,K,Pi. For WDuo3 the ratios were PRass=27 and PRdiss=22, respectively. For Duo3, the interaction with free and [3H]NMS-occupied receptors only slightly depended on the composition of the incubation medium: PRass=1.3, PRdiss=2.8. In contrast to the other agents, the concentration-effect curves of which had slope factors nH not different from unity, the curves of Duo3 were steep (nH about -1.6). For alcuronium the shift factors amounted to PRass=29 and PRdiss=25, for gallamine to PRass=216 and PRdiss=159. In conclusion, there was a wide variation between the allosteric agents with regard to the respective buffer dependence of action. Yet, for a given allosteric agent, the interaction with either free or [3H]NMS-occupied receptors was always characterized by the same buffer-dependent shift. Thus, even the applied rod-shaped allosteric agents do not appear to switch to the orthosteric site in free compared with orthoster-occupied M2 receptors.
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Affiliation(s)
- A Schröter
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Germany
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Zlotos DP, Buller S, Tränkle C, Mohr K. Bisquaternary caracurine V derivatives as allosteric modulators of ligand binding to M2 acetylcholine receptors. Bioorg Med Chem Lett 2000; 10:2529-32. [PMID: 11086722 DOI: 10.1016/s0960-894x(00)00509-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 10/18/2022]
Abstract
The allosteric effect on muscarinic acetylcholine M2 receptors of 11 bisquaternary salts of the Strychnos alkaloid caracurine V was determined. The effect was indicated by the concentration which retarded the rate of dissociation of the antagonist [3H]-N-methylscopolamine from porcine cardiac cholinoceptors by a factor of 2 (EC50). The most potent compounds carry allyl and propargyl substituents, respectively. Introduction of more bulky substituents (e.g., benzyl groups) resulted in a considerably reduced allosteric potency. The wide range of EC50 values (3 nM for R = allyl. 1750 nM for R = 2-naphthyl) suggests a sterically restricted binding pocket. Molecular modeling studies indicated that the caracurine V ring system satisfies the pharmacophore model for the allosteric interaction.
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Affiliation(s)
- D P Zlotos
- Pharmaceutical Institute, University of Würzburg, Germany.
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Botero Cid HM, Tränkle C, Baumann K, Pick R, Mies-Klomfass E, Kostenis E, Mohr K, Holzgrabe U. Structure-activity relationships in a series of bisquaternary bisphthalimidine derivatives modulating the muscarinic M(2)-receptor allosterically. J Med Chem 2000; 43:2155-64. [PMID: 10841794 DOI: 10.1021/jm991136e] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [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: 11/28/2022]
Abstract
Hexane-bisammonium-type compounds containing lateral phthalimide moieties are well-established ligands of the common allosteric binding site of muscarinic M(2) receptors. Previous structure-activity relationships (SAR) revealed two positively charged centers and two lateral phthalimide moieties in a defined arrangement to be essential of a high allosteric potency. The purpose of this study was to replace one carbonyl group of the phthalimides with hydrogens, hydroxy, alkoxy, phenyl, benzyl, and benzylidene groups in order to check the influence of these substituents on the allosteric activity in antagonist-linked receptors. The analysis of the quantitative SAR indicated that a high allosteric potency is related to a certain amount of rigidity as well as polarizibility and the ability to form hydrophobic interactions.
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Affiliation(s)
- H M Botero Cid
- Pharmaceutical Chemistry, Institute of Pharmacy, University of Würzburg
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Bender W, Staudt M, Tränkle C, Mohr K, Holzgrabe U. Probing the size of a hydrophobic binding pocket within the allosteric site of muscarinic acetylcholine M2-receptors. Life Sci 2000; 66:1675-82. [PMID: 10809164 DOI: 10.1016/s0024-3205(00)00490-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [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: 10/17/2022]
Abstract
Hexane-bisammonium-type compounds containing lateral phthalimide moieties are known to have a rather high affinity for the allosteric site of muscarinic M2 receptors. In order to get more insight into the contribution of the lateral substituents for alloster binding affinity, a series of compounds with unilaterally varying imide substituents were synthesized and tested for their ability to retard allosterically the dissociation of [3H]N-methylscopolamine from the receptor protein (control t1/2 = 2 min; 3 mM MgHCO4, 50 mM Tris, pH 7.3, 37 degrees C). Among the test compounds, the naphthalimide containing agent (half maximum effect at ECs5,diss = 60 nM) revealed the highest potency. Apparently, its affinity for the allosteric site in NMS-occupied receptors is 20fold higher compared with the phthalimide containing parent compound W 84. Analysis of quantitative structure-activity relationships yielded a parabolic correlation between the volume of the lateral substituents and the allosteric potency. The maximal volume was determined to be approximately 600 A3 suggesting that the allosteric binding site contains a binding pocket of a defined size for the imide moiety.
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Affiliation(s)
- W Bender
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Würzburg, Germany
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40
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Holzgrabe U, Bender W, Cid HM, Staudt M, Pick R, Pfletschinger C, Balatková E, Tränkle C, Mohr K. Ligands for the common allosteric site of acetylcholine M2-receptors: development and application. Pharm Acta Helv 2000; 74:149-55. [PMID: 10812952 DOI: 10.1016/s0031-6865(99)00028-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ligands for the allosteric site of acetylcholine M2 receptors are able to retard the dissociation of simultaneously bound ligands for the orthosteric site. This effect promotes receptor occupation by the orthosteric ligand. The allosteric effect opens various therapeutic perspectives, e.g., in organophosphorus poisoning. The aim of our studies was to optimize the affinity of the modulators for the common allosteric binding site of muscarinic M2 receptors, the orthosteric site of which was liganded with the N-methylscolopamine. The phthalimido substituted hexane-bisammonium compound W84 served as a starting point. Previous molecular modelling studies revealed two positive charges and two aromatic imides in a sandwich-like arrangement to be essential for a high allosteric potency. A three-dimensional quantitative structure activity relationship (3D QSAR) analysis predicted compounds with substituents of increasing size on the lateral imide moieties to enhance the affinity for the allosteric binding site. Thus, we synthesized and pharmacologically evaluated compounds bearing "saturated" phthalimide moieties as well as phthalimidines with substituents of systematically increasing size in position 3 or on the aromatic ring at one or both ends of the molecule. Within each series, QSAR could be derived: 1. "Saturation" of the aromatic ring of the phthalimide moiety results in less potent compounds. 2. Increasing the size of the substituents in position 3 of the phthalimide enhances the potency. 3. Putting substituents on the aromatic part of the phthalimide increases the potency more effectively: the introduction of a methyl group in position 5 gave a compound with a potency in the nanomolar concentration range which was subsequently developed as the first radioligand for the allosteric binding site.
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Affiliation(s)
- U Holzgrabe
- Department of Pharmaceutical Chemistry, University of Würzburg, Germany.
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41
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Pfaffendorf M, Batink HD, Tränkle C, Mohr K, van Zwieten PA. Probing the selectivity of allosteric modulators of muscarinic receptors at other G-protein-coupled receptors. J Auton Pharmacol 2000; 20:55-62. [PMID: 11048962 DOI: 10.1046/j.1365-2680.2000.00163.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The aim of the present investigation was to analyse whether three prototype allosteric modulators of ligand binding to muscarinic receptors, i.e. alcuronium, gallamine, and the alkane-bis-ammonium compound W84 (hexane-1,6-bis[dimethyl-3'-phthalimidopropylammonium bromide]), may have allosteric effects on radioligand-binding characteristics at other G-protein-coupled receptors, such as cerebral A1 adenosine receptors (Gi-coupled), cardiac left ventricular alpha1-adrenoceptors (Gq), and beta-adrenoceptors (Gs). 2. The modulators were applied at concentrations known to be high with regard to the allosteric delay of the dissociation of the antagonist [3H]-N-methylscopolamine (NMS) from muscarinic M2-receptors: 30 micromol l(-1) W84, 30 micromol l(-1) alcuronium, 1000 micromol l(-1) gallamine. As radioligands, we used the adenosine A1-receptor ligand [3H]-cyclopentyl-dipropylxanthine (CPX), the alpha1-adrenoceptor ligand [3H]-prazosin (PRAZ), and the beta-adrenoceptor ligand (-)-[125I]-iodocyanopindolol (ICYP). Allosteric actions on ligand dissociation and the equilibrium binding were measured in the membrane fractions of rat whole forebrain (CPX) and of rat cardiac left ventricle (PRAZ, ICYP, NMS), respectively. 3. CPX and PRAZ showed a monophasic dissociation with half-lives of 5.88+/-0.15 and 12.27+/-0.46 min, respectively. In the case of CPX, neither the binding at equilibrium nor the dissociation characteristics were influenced by the allosteric agents. With PRAZ, the binding at equilibrium remained almost unaltered in the presence of W84, whereas it was reduced to 36+/-2% of the control value with alcuronium and to 42+/-2% with gallamine. The dissociation of PRAZ was not affected by W84, whereas it was moderately accelerated by alcuronium and gallamine. In the case of ICYP, the binding at equilibrium was not affected by the allosteric modulators. The dissociation of ICYP was slow, and after 3 h, more than 50% of the radioligand was still bound, so that a reliable half-life could not be calculated. ICYP dissociation was not affected by W84. In the presence of alcuronium and gallamine, the dissociation curve of ICYP revealed an initial drop from the starting level, followed by the major phase of dissociation being parallel to the control curve. 4. In summary, the allosteric action of the applied agents is not a common feature of G-protein-coupled receptors and appears to be specific for muscarinic receptors.
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Affiliation(s)
- M Pfaffendorf
- Department of Pharmacotherapy, Academic Medical Center, University of Amsterdam, The Netherlands
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Franken C, Tränkle C, Mohr K. Testing the specificity of allosteric modulators of muscarinic receptors in phylogenetically closely related histamine H1-receptors. Naunyn Schmiedebergs Arch Pharmacol 2000; 361:107-12. [PMID: 10685864 DOI: 10.1007/s002109900176] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gallamine, alcuronium and W84 (hexane-1,6-bis[dimethyl-3'-phthalimidopropyl-ammonium bromide]) are prototype allosteric modulators of the G-protein coupled muscarinic acetylcholine receptor family, especially of the M2-subtype. In order to probe the specificity of muscarinic allosteric modulation, we checked whether these agents interact with histamine H1-receptors which have a high homology with muscarinic receptors. Binding experiments (38 mM Na2HPO4, 12 mM KH2PO4, pH 7.5) were performed with the H1-receptor antagonist [3H]mepyramine ([3H]MEP) in guinea pig cerebellar homogenates. For the sake of comparison, binding of [3H]N-methylscopolamine ([3H]NMS) at muscarinic M2-receptors was measured in porcine cardiac homogenates under identical conditions. The modulators retarded [3H]NMS dissociation (t1/2 control=1.3 min) concentration-dependently indicating their allosteric action with half-maximum effects for gallamine at EC50,discs=27 microM, for alcuronium at EC50,diss=53 nM, and for W84 at EC50,diss=170 nM. In contrast, [3H]MEP dissociation from H1-receptors (t1/2,control=2.6 min) remained unchanged up to concentrations of 1 mM of the modulators. Equilibrium binding of [3H]NMS (KD=0.46 nM, Bmax=98 fmol/mg protein) was inhibited by gallamine, elevated by alcuronium and left almost unchanged by W84, indicating negative, positive and nearly neutral cooperativity, respectively, with the radioligand. The ternary complex model of allosteric actions yielded the equilibrium dissociation constants K(A) for the binding of the allosteric modulators to free M2-receptors: K(A,gallamine)=100 nM, K(A,alcuronium)=450 nM, K(A,W84)=69 nM. In H1-receptors, more than 1,000-fold higher concentrations than in M2-receptors were required to elicit an effect on the binding of [3H]MEP (KD=1.2 nM, Bmax=205 fmol/mg protein). Half-maximal reduction was observed at 10 mM for gallamine, 1 mM for alcuronium and 92 microM for W84. In conclusion, the muscarinic modulators have little effect on the histamine H1-receptors.
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Affiliation(s)
- C Franken
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Germany.
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43
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Schröter A, Mohr K. [Does budesonide affect growth?]. Dtsch Med Wochenschr 1999; 124:1324. [PMID: 10596297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Affiliation(s)
- A Schröter
- Pharmakologie und Toxíkologie, Pharmazeutisches Institut der Universität Bonn
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Tränkle C, Weyand O, Schröter A, Mohr K. Using a radioalloster to test predictions of the cooperativity model for gallamine binding to the allosteric site of muscarinic acetylcholine M(2) receptors. Mol Pharmacol 1999; 56:962-5. [PMID: 10531401 DOI: 10.1124/mol.56.5.962] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [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: 11/22/2022] Open
Abstract
The muscarinic M(2) receptor contains an orthosteric and an allosteric site. Binding of an allosteric agent may induce a shift alpha of the equilibrium dissociation constant K(D) of a radioligand for the orthosteric site. According to the cooperativity model, the K(A) of alloster binding is expected to be shifted to an identical extent depending on whether the orthosteric site is occupied by the orthoster or not. Here, the novel radioalloster [(3)H]dimethyl-W84 (N,N'-bis[3-(1,3-dihydro-1, 3-dioxo-4-methyl-2H-isoindol-2-yl)propyl]-N,N,N',N'-tetramethyl-1, 6-hexanediaminium diiodide) was applied to directly measure the K(A) shift induced for the prototype allosteric modulator gallamine by binding of N-methylscopolamine (NMS) to the orthosteric site of porcine heart M(2) receptors (4 mM Na(2)HPO(4), 1 mM KH(2)PO(4), pH 7.4; 23 degrees C; data are means +/- S.E.). First, in the common way, the concentration-dependent inhibition by gallamine of [(3)H]NMS equilibrium binding was measured and analyzed using the cooperativity model, which yielded for the affinity of gallamine binding at free receptors a pK(A)= 8.35 +/- 0.09 and a cooperativity factor alpha = 46 (n = 5). The dissociation constant for gallamine binding at NMS-occupied receptors was predicted as p(alpha. K(A)) = 6.69. Labeling of the allosteric site by [(3)H]dimethyl-W84 allowed the measure of competitive displacement curves for gallamine. The K(i) for gallamine at free receptors amounted to pK(i,-NMS) = 8.27 +/- 0.39 (n = 5), which is in line with the prediction of the cooperativtiy model. In the presence of 1 microM NMS, to occupy the orthosteric site, gallamine displaced [(3)H]dimethyl-W84 with pK(i, +NMS) = 6.60 +/- 0.19 (n = 3). Thus, the NMS-induced pK(i) shift amounted to 47, which matches the predicted value of alpha = 46. These results validate the cooperativity model.
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Affiliation(s)
- C Tränkle
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Bonn, Germany
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Klein CD, Klingmüller M, Schellinski C, Landmann S, Hauschild S, Heber D, Mohr K, Hopfinger AJ. Synthesis, pharmacological and biophysical characterization, and membrane-interaction QSAR analysis of cationic amphiphilic model compounds. J Med Chem 1999; 42:3874-88. [PMID: 10508436 DOI: 10.1021/jm980694a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [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: 11/28/2022]
Abstract
Cationic amphiphilic drugs have a propensity to interact with biological interphases. This study was designed to gain more insight into the molecular properties of catamphiphilic drugs which govern this type of interaction. A series of phenylpropylamine model compounds were synthesized in which modifications were incorporated at the aromatic part of the molecule. The replacement of (45)Ca(2+) from phosphatidylserine monolayers served to monitor drug binding to the phospholipid. The influence on the phase-transition temperature of liposomes of dipalmitoylphosphatidic acid was measured to assess the perturbing action of the drugs on the structural organization of phospholipid assemblies. The antiarrhythmic activity of the compounds was determined in Langendorff preparations of guinea pig hearts to assess the membrane-stabilizing action. Quantitative structure-activity relationship (QSAR) models for these endpoints were developed using both intra- and intermolecular QSAR descriptors. Intermolecular membrane-interaction descriptors were derived from molecular dynamics simulations of the compounds in a model phospholipid monolayer. QSAR models were derived for all endpoints using partial least-squares regression (PLS) and a genetic algorithm tool, the genetic function approximation (GFA). Membrane-interaction descriptors appear to be of a particular importance in explaining the influence of the compounds on the phase-transition temperature of DPPA liposomes, while the other endpoints can be adequately modeled by intramolecular descriptors. The calcium-displacing activity at phosphatidylserine monolayers is governed by the electrostatic properties of the compounds. Measures of lipophilicity and molecular size are of particular importance for antiarrhythmic activity. Possible improvements to both the molecular modeling and the applied computational protocol of membrane-solute systems are identified and discussed.
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Affiliation(s)
- C D Klein
- Laboratory of Molecular Modeling and Design, M/C 781, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612-7231, USA
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46
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Ohnmacht U, Tränkle C, Mohr K, Gmeiner P. [3H]Pramipexole: a selective radioligand for the high affinity dopamine D2 receptor in bovine striatal membranes. Pharmazie 1999; 54:294-7. [PMID: 10234741] [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] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The characterization of [3H]pramipexole binding to bovine striatal membranes is reported in full experimental detail. According to kinetic experiments, saturation and competition studies a single binding site can be selectively labeled which turned out to be the high affinity D2 receptor. Addition of GPP(NH)P resulted in almost complete loss of specific binding. The bovine D2 subtype shows high sequence identity with the human D2 receptor indicating that the heterologous competition assays are of interest for the evaluation of neurotropic drug candidates. Using the representative D2 agonists (+)-7-OH-DPAT, (-)-3-PPP and (S)-7-dipropylaminotetrahydroindolizine the same rank order of affinities was determined as described for rat striata labeled with [3H]pramipexole, however, the Ki values turned out to be significantly higher. Furthermore, the system facilitates structure activity relationship studied on D2 affinity modulating peptides. Using L-prolyl-L-leucyl-glycinamide as an example a significant increase of specific radioligand binding could be measured.
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Affiliation(s)
- U Ohnmacht
- Institut für Pharmazie und Lebensmittelchemie der Universität Erlangen-Nürnberg, Germany
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Thomas C, Ohnmacht U, Zahn K, Mohr K, Gmeiner P. Ex-chiral pool synthesis and pharmacological aspects of 3-pyrrolidinylisoxazoles. Pharmazie 1999; 54:248-50. [PMID: 10234735] [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] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Employing the dopamine autoreceptor agonist (-)-3-PPP (3) as well as the cholinergic receptor ligands 4 and 5 as lead compounds the 3-pyrrolidinylisoxazoles 2a,b as well as its optical antipodes ent 2a,b were synthesized from (R)-aspartic acid (6) and (S)-aspartic acid (ent-6), respectively. Pharmacological properties of the target compounds were evaluated employing dopamine D2 receptor binding studies and functional experiments on muscarinic M2 receptors.
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Affiliation(s)
- C Thomas
- Institut für Pharmazie und Lebensmittelchemie der Universität Erlangen-Nürnberg, Germany
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48
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Nassif-Makki T, Tränkle C, Zlotos D, Bejeuhr G, Cambareri A, Pfletschinger C, Kostenis E, Mohr K, Holzgrabe U. Bisquaternary ligands of the common allosteric site of M2 acetylcholine receptors: search for the minimum essential distances between the pharmacophoric elements. J Med Chem 1999; 42:849-58. [PMID: 10072682 DOI: 10.1021/jm981023f] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [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: 11/28/2022]
Abstract
Structurally diverse molecules, such as alcuronium, gallamine, and tubocurarine as well as W84 and WDUO, are known to interact allosterically with ligand binding to muscarinic M2 acetylcholine receptors. Preliminary molecular modeling studies revealed two positive charges in the middle and two lateral aromatic areas to be essential elements of a high allosteric potency. To find out the optimum distances between these pharmacophoric elements, a systematic variation of the spacer in the series of W84, WDUO, and IWDUO compounds was performed. The allosteric reduction of the rate of dissociation of the antagonist [3H]-N-methylscopolamine from porcine heart M2 receptors served as a test system. The minimal essential distance between the positive charges was found to be 10 A. The length of the peripheral spacers connecting the positive charge and the lateral aromatic moiety appears to depend on the chemical functionality; the peripheral spacers have to be long and flexible enough to position the aromatic skeletons in the spatial neighborhood of the alkane middle chain: in the case of an oxime ether containing peripheral spacer, six atoms are required, and in the case of an alkane chain, four carbon atoms are necessary to adopt the pharmacophoric S-shape conformation.
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Affiliation(s)
- T Nassif-Makki
- Pharmaceutical Chemistry and Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Kreuzbergweg 26, D-53115 Bonn, Germany
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49
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Schröter A, Tränkle C, Mohr K. Modes of allosteric interactions with muscarinic M2 receptors as deduced from buffer-dependent potency shifts. Life Sci 1999. [DOI: 10.1016/s0024-3205(99)90475-7] [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: 10/26/2022]
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50
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Tränkle C, Mies-Klomfass E, Cid MH, Holzgrabe U, Mohr K. Identification of a [3H]Ligand for the common allosteric site of muscarinic acetylcholine M2 receptors. Mol Pharmacol 1998; 54:139-45. [PMID: 9658199 DOI: 10.1124/mol.54.1.139] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [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: 11/22/2022] Open
Abstract
Muscarinic acetylcholine receptors bind allosteric modulators at a site apart from the orthosteric site used by conventional ligands. We tested in cardiac tissue whether modulator binding to ligand-occupied muscarinic M2 receptors is a preferential event that can be detected using a radioactive allosteric agent. The newly synthesized dimethyl-W84 (N,N'-bis[3-(1,3-dihydro-1, 3-dioxo-4-methyl-2H-isoindol-2-yl)propyl]-N,N,N',N'-tetramethyl-1, 6-hexanediaminium diiodide) has a particular high potency at M2 receptors occupied by the conventional antagonist N-methylscopolamine (NMS); dissociation of [3H]NMS is half-maximally retarded at an EC50,diss value of 3 nM. Using obidoxime as an "allosteric antagonist," evidence was found that dimethyl-W84 interacts with the postulated common allosteric site. Binding of [3H]dimethyl-W84 (0.3 nM; specific activity, 168 Ci/mmol) was measured in porcine heart homogenates (4 mM Na2HPO4, 1 mM KH2PO4, pH 7.4, 23 degrees) in the presence of 1 microM NMS. Homologous competition experiments revealed two components of saturable radioligand binding: one with a high affinity (KD = 2 nM) and small capacity ( approximately 30% of total saturable binding) and the other with a 20,000-fold lower affinity. The Bmax value of the high affinity sites (68 fmol/mg protein) matched muscarinic receptor density as determined by [3H]NMS (79 fmol/mg). Prototype allosteric agents, alcuronium, W84 (the parent compound of the radioligand), and gallamine, displaced high affinity [3H]dimethyl-W84 binding concentration-dependently (pKi values = 8.62, 7.83, and 6.72, respectively). The binding affinities of the modulators were in excellent correlation with their potencies to allosterically stabilize NMS/receptor complexes (EC50,diss = 8.40, 7.72, and 6.74, respectively). We conclude that high affinity binding of [3H]dimethyl-W84 reflects occupation of the common allosteric site of M2 receptors.
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Affiliation(s)
- C Tränkle
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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