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Humpert S, Schneider D, Bier D, Schulze A, Neumaier F, Neumaier B, Holschbach M. 8-Bicycloalkyl-CPFPX derivatives as potent and selective tools for in vivo imaging of the A 1 adenosine receptor. Eur J Med Chem 2024; 271:116380. [PMID: 38615410 DOI: 10.1016/j.ejmech.2024.116380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/16/2024]
Abstract
Imaging of the A1 adenosine receptor (A1R) by positron emission tomography (PET) with 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propyl-xanthine ([18F]CPFPX) has been widely used in preclinical and clinical studies. However, this radioligand suffers from rapid peripheral metabolism and subsequent accumulation of radiometabolites in the vascular compartment. In the present work, we prepared four derivatives of CPFPX by replacement of the cyclopentyl group with norbornane moieties. These derivatives were evaluated by competition binding studies, microsomal stability assays and LC-MS analysis of microsomal metabolites. In addition, the 18F-labeled isotopologue of 8-(1-norbornyl)-3-(3-fluoropropyl)-1-propylxanthine (1-NBX) as the most promising candidate was prepared by radiofluorination of the corresponding tosylate precursor and the resulting radioligand ([18F]1-NBX) was evaluated by permeability assays with Caco-2 cells and in vitro autoradiography in rat brain slices. Our results demonstrate that 1-NBX exhibits significantly improved A1R affinity and selectivity when compared to CPFPX and that it does not give rise to lipophilic metabolites expected to cross the blood-brain-barrier in microsomal assays. Furthermore, [18F]1-NBX showed a high passive permeability (Pc = 6.9 ± 2.9 × 10-5 cm/s) and in vitro autoradiography with this radioligand resulted in a distribution pattern matching A1R expression in the brain. Moreover, a low degree of non-specific binding (5%) was observed. Taken together, these findings identify [18F]1-NBX as a promising candidate for further preclinical evaluation as potential PET tracer for A1R imaging.
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Affiliation(s)
- Swen Humpert
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Daniela Schneider
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Dirk Bier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Annette Schulze
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany; Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany; Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany; Max Planck Institute for Metabolism Research, Gleueler Straße 50, 50931, Cologne, Germany.
| | - Marcus Holschbach
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
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Humpert S, Schneider D, Lang M, Schulze A, Neumaier F, Holschbach M, Bier D, Neumaier B. Radiosynthesis and In Vitro Evaluation of [ 11C]tozadenant as Adenosine A 2A Receptor Radioligand. Molecules 2024; 29:1089. [PMID: 38474602 DOI: 10.3390/molecules29051089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Tozadenant (4-hydroxy-N-(4-methoxy-7-morpholinobenzo[d]thiazol-2-yl)-4-methylpiperidine-1-carboxamide) is a highly selective adenosine A2A receptor (A2AR) antagonist and a promising lead structure for the development of A2AR-selective positron emission tomography (PET) probes. Although several 18F-labelled tozadenant derivatives showed favorable in vitro properties, recent in vivo PET studies observed poor brain penetration and lower specific binding than anticipated from the in vitro data. While these findings might be attributable to the structural modification associated with 18F-labelling, they could also reflect inherent properties of the parent compound. However, PET studies with radioisotopologues of tozadenant to evaluate its cerebral pharmacokinetics and brain distribution are still lacking. In the present work, we applied N-Boc-O-desmethyltozadenant as a suitable precursor for the preparation of [O-methyl-11C]tozadenant ([11C]tozadenant) by O-methylation with [11C]methyl iodide followed by acidic deprotection. This approach afforded [11C]tozadenant in radiochemical yields of 18 ± 2%, with molar activities of 50-60 GBq/µmol (1300-1600 mCi/µmol) and radiochemical purities of 95 ± 3%. In addition, in vitro autoradiography in pig and rat brain slices demonstrated the expected striatal accumulation pattern and confirmed the A2AR specificity of the radioligand, making it a promising tool for in vivo PET studies on the cerebral pharmacokinetics and brain distribution of tozadenant.
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Affiliation(s)
- Swen Humpert
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Daniela Schneider
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Markus Lang
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Annette Schulze
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Marcus Holschbach
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Dirk Bier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
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Schneider D, Schulze A, Humpert S, Holschbach M, Bier D, Neumaier B. Evaluation of a multifunctional blood-brain barrier co-culture model prepared from rat primary brain endothelial cells and astrocytes: first results. Nucl Med Biol 2022. [DOI: 10.1016/s0969-8051(22)00233-5] [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: 10/18/2022]
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Cologni R, Ermert J, Carloni P, Neumaier B, Holschbach M, Bier D. 18F-labelled probes for non-invasive assessment of the IDH genotype in diffuse glioma. Nucl Med Biol 2022. [DOI: 10.1016/s0969-8051(22)00081-6] [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: 10/18/2022]
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Hoffmann C, Evcüman S, Neumaier F, Zlatopolskiy BD, Humpert S, Bier D, Holschbach M, Schulze A, Endepols H, Neumaier B. [ 18F]ALX5406: A Brain-Penetrating Prodrug for GlyT1-Specific PET Imaging. ACS Chem Neurosci 2021; 12:3335-3346. [PMID: 34449193 DOI: 10.1021/acschemneuro.1c00284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Selective inhibition of glycine transporter 1 (GlyT1) has emerged as a potential approach to alleviate N-methyl-d-aspartate receptor (NMDAR) hypofunction in patients with schizophrenia and cognitive decline. ALX5407 is a potent and selective inhibitor of GlyT1 derived from the metabolic intermediate sarcosine (N-methylglycine) that showed antipsychotic potential in a number of animal models. Whereas clinical application of ALX5407 is limited by adverse effects on motor performance and respiratory function, a suitably radiolabeled drug could represent a promising PET tracer for the visualization of GlyT1 in the brain. Herein, [18F]ALX5407 and the corresponding methyl ester, [18F]ALX5406, were prepared by alcohol-enhanced copper mediated radiofluorination and studied in vitro in rat brain slices and in vivo in normal rats. [18F]ALX5407 demonstrated accumulation consistent with the distribution of GlyT1 in in vitro autoradiographic studies but no brain uptake in μPET experiments in naı̈ve rats. In contrast, the methyl ester [18F]ALX5406 rapidly entered the brain and was enzymatically transformed into [18F]ALX5407, resulting in a regional accumulation pattern consistent with GlyT1 specific binding. We conclude that [18F]ALX5406 is a promising and easily accessible PET probe for preclinical in vivo imaging of GlyT1 in the brain.
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Affiliation(s)
- Chris Hoffmann
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Sibel Evcüman
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Felix Neumaier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Boris D. Zlatopolskiy
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Swen Humpert
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Dirk Bier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Marcus Holschbach
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Annette Schulze
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Heike Endepols
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
- Nuclear Medicine Department, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
| | - Bernd Neumaier
- Nuclear Chemistry (INM-5), Institute of Neuroscience and Medicine, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine, and University Hospital Cologne, 50937 Cologne, Germany
- Max Planck Institute of Metabolism Research, 50931 Cologne, Germany
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Evcüman S, Holschbach M, Bier D, Zlatopolskiy B, Neumaier B. Development and biological evaluation of 18F-labeled adenosine-A1-receptor partial agonists. Nucl Med Biol 2021. [DOI: 10.1016/s0969-8051(21)00281-x] [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: 10/21/2022]
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Renk DR, Skraban M, Bier D, Schulze A, Wabbals E, Wedekind F, Neumaier F, Neumaier B, Holschbach M. Design, synthesis and biological evaluation of Tozadenant analogues as adenosine A 2A receptor ligands. Eur J Med Chem 2021; 214:113214. [PMID: 33548636 DOI: 10.1016/j.ejmech.2021.113214] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 12/19/2022]
Abstract
With the aim to obtain potent adenosine A2A receptor (A2AR) ligands, a series of eighteen derivatives of 4-hydroxy-N-(4-methoxy-7-morpholin-4-yl-1,3-benzo[d]thiazol-2-yl)-4-methylpiperidine-1-carboxamide (SYN-115, Tozadenant) were designed and synthesized. The target compounds were obtained by a chemical building block principle that involved reaction of the appropriate aminobenzothiazole phenyl carbamates with either commercially available or readily synthesized functionalized piperidines. Their affinity and subtype selectivity with regard to human adenosine A1-and A2A receptors were determined using radioligand binding assays. Ki values for human A2AR ranged from 2.4 to 38 nM, with more than 120-fold selectivity over A1 receptors for all evaluated compounds except 13k which had a Ki of 361 nM and 18-fold selectivity. The most potent fluorine-containing derivatives 13e, 13g and 13l exhibited Ki values of 4.9 nM, 3.6 nM and 2.8 nM for the human A2AR. Interestingly, the corresponding values for rat A2AR were found to be four to five times higher. Their binding to A2AR was further confirmed by radiolabeling with 18F and in vitro autoradiography in rat brain slices, which showed almost exclusive striatal binding and complete displacement by the A2AR antagonist ZM 241385. We conclude that these compounds represent potential candidates for the visualization of the A2A receptor and open pathways to novel therapeutic treatments of neurodegenerative disorders or cancer.
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Affiliation(s)
- Dana R Renk
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging, Kerpener Straße 62, 50937, Köln, Germany; Forschungszentrum Jülich GmbH, Germany
| | - Marcel Skraban
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; Forschungszentrum Jülich GmbH, Germany
| | - Dirk Bier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; Forschungszentrum Jülich GmbH, Germany
| | - Annette Schulze
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; Forschungszentrum Jülich GmbH, Germany
| | - Erika Wabbals
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; Forschungszentrum Jülich GmbH, Germany
| | - Franziska Wedekind
- Molecular Organization of the Brain (INM-2), Wilhelm-Johnen-Straße, 52428, Jülich, Germany; Forschungszentrum Jülich GmbH, Germany
| | - Felix Neumaier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging, Kerpener Straße 62, 50937, Köln, Germany; Forschungszentrum Jülich GmbH, Germany
| | - Bernd Neumaier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging, Kerpener Straße 62, 50937, Köln, Germany; Forschungszentrum Jülich GmbH, Germany
| | - Marcus Holschbach
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Germany; Forschungszentrum Jülich GmbH, Germany.
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Bier D, Schulze A, Holschbach M, Neumaier B, Baumann A. Development and Evaluation of a Versatile Receptor-Ligand Binding Assay Using Cell Membrane Preparations Embedded in an Agarose Gel Matrix and Evaluation with the Human Adenosine A1Receptor. Assay Drug Dev Technol 2020; 18:328-340. [DOI: 10.1089/adt.2020.991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Dirk Bier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Annette Schulze
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Marcus Holschbach
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Bernd Neumaier
- Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Arnd Baumann
- Institute of Biological Information Processing, Molecular and Cell Physiology (IBI-1), Forschungszentrum Jülich GmbH, Jülich, Germany
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Schneider D, Oskamp A, Holschbach M, Neumaier B, Bier D, Bauer A. Influence of binding affinity and blood plasma level on cerebral pharmacokinetics and PET imaging characteristics of two novel xanthine PET radioligands for the A1 adenosine receptor. Nucl Med Biol 2020; 82-83:1-8. [DOI: 10.1016/j.nucmedbio.2019.12.001] [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] [Received: 10/09/2019] [Revised: 11/16/2019] [Accepted: 12/01/2019] [Indexed: 10/25/2022]
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Schneider D, Oskamp A, Holschbach M, Neumaier B, Bauer A, Bier D. Relevance of In Vitro Metabolism Models to PET Radiotracer Development: Prediction of In Vivo Clearance in Rats from Microsomal Stability Data. Pharmaceuticals (Basel) 2019; 12:ph12020057. [PMID: 31013984 PMCID: PMC6631687 DOI: 10.3390/ph12020057] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 04/10/2019] [Accepted: 04/12/2019] [Indexed: 01/03/2023] Open
Abstract
The prediction of in vivo clearance from in vitro metabolism models such as liver microsomes is an established procedure in drug discovery. The potentials and limitations of this approach have been extensively evaluated in the pharmaceutical sector; however, this is not the case for the field of positron emission tomography (PET) radiotracer development. The application of PET radiotracers and classical drugs differs greatly with regard to the amount of substance administered. In typical PET imaging sessions, subnanomolar quantities of the radiotracer are injected, resulting in body concentrations that cannot be readily simulated in analytical assays. This raises concerns regarding the predictability of radiotracer clearance from in vitro data. We assessed the accuracy of clearance prediction for three prototypical PET radiotracers developed for imaging the A1 adenosine receptor (A1AR). Using the half-life (t1/2) approach and physiologically based scaling, in vivo clearance in the rat model was predicted from microsomal stability data. Actual clearance could be accurately predicted with an average fold error (AFE) of 0.78 and a root mean square error (RMSE) of 1.6. The observed slight underprediction (1.3-fold) is in accordance with the prediction accuracy reported for classical drugs. This result indicates that the prediction of radiotracer clearance is possible despite concentration differences of more than three orders of magnitude between in vitro and in vivo conditions. Consequently, in vitro metabolism models represent a valuable tool for PET radiotracer development.
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Affiliation(s)
- Daniela Schneider
- Institute of Neuroscience and Medicine-Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Angela Oskamp
- Institute of Neuroscience and Medicine-Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Marcus Holschbach
- Institute of Neuroscience and Medicine-Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Bernd Neumaier
- Institute of Neuroscience and Medicine-Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Andreas Bauer
- Institute of Neuroscience and Medicine-Molecular Organization of the Brain (INM-2), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
- Neurological Department, Medical Faculty, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Dirk Bier
- Institute of Neuroscience and Medicine-Nuclear Chemistry (INM-5), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
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Cavani M, Bier D, Holschbach M, Coenen HH. Efficient synthesis of [ 18 F]FPyME: A new approach for the preparation of maleimide-containing prosthetic groups for the conjugation with thiols. J Labelled Comp Radiopharm 2016; 60:87-92. [PMID: 27862235 DOI: 10.1002/jlcr.3469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [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: 06/09/2016] [Revised: 08/31/2016] [Accepted: 09/26/2016] [Indexed: 11/08/2022]
Abstract
An improved high yielding radiosynthesis of the known thiol-reactive maleimide-containing prosthetic group1-[3-(2-[18 F]fluoropyridine-3-yloxy)propyl]pyrrole-2,5-dione ([18 F]FPyME) is described. The target compound was obtained by a two-step one-pot procedure starting from a maleimide-containing nitro-precursor that was protected as a Diels-Alder adduct with 2,5-dimethylfurane. Nucleophilic radiofluorination followed by heat induced deprotection through a Retro Diels Alder reaction yielded, after chromatographic isolation, [18 F]FPyME with a radiochemical yield of 20% in about 60 min overall synthesis time. A variety of other [18 F]fluoropyridine based maleimide-containing prosthetic groups should be accessible via the described synthetic strategy.
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Affiliation(s)
- Melanie Cavani
- Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry Forschungszentrum Jülich, Jülich, Germany
| | - Dirk Bier
- Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry Forschungszentrum Jülich, Jülich, Germany
| | - Marcus Holschbach
- Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry Forschungszentrum Jülich, Jülich, Germany
| | - Heinz H Coenen
- Institute of Neuroscience and Medicine, INM-5: Nuclear Chemistry Forschungszentrum Jülich, Jülich, Germany
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Bier D, Hartmann R, Holschbach M. Collision-induced dissociation studies of caffeine in positive electrospray ionisation mass spectrometry using six deuterated isotopomers and one N1-ethylated homologue. Rapid Commun Mass Spectrom 2013; 27:885-895. [PMID: 23495058 DOI: 10.1002/rcm.6520] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 01/19/2013] [Accepted: 01/21/2013] [Indexed: 06/01/2023]
Abstract
RATIONALE In order to deepen the understanding of electrospray ionisation collision-induced dissociation (ESI-CID) fragmentation reactions of xanthine derivatives for the identification of metabolites using low-resolution liquid chromatography/mass spectrometry (LC/MS) analysis, basic experiments using caffeine (1,3,7-trimethylxanthine) as model compound have been performed. METHODS Six deuterium isotopomers and one N1-ethylated homologue of caffeine have been synthesized and their ESI fragmentation spectra have been obtained by using LC/MS in combination with either standard or perdeuterated eluent mixtures. RESULTS One result of these studies is the finding that the positive charges of the ESI-CID caffeine fragments are caused by the addition of protons. Furthermore, the performed experiments allow the determination of all molecular formulae of each ESI-CID caffeine fragment. CONCLUSIONS As basic CID reactions of caffeine have been elucidated in this work, the developed fragmentation scheme may serve as a valuable tool for the interpretation of ESI-CID fragmentation spectra of more complex xanthine derivatives and their respective metabolites.
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Affiliation(s)
- Dirk Bier
- Institut für Neurowissenschaften und Medizin (INM-5), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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Boy C, Holschbach M, Herzog H, Bauer A, Coenen HH, Zilles K. Präoperative Untersuchung in der Epilepsiechirurgie: GABA- und Adenosinrezeptoren bei pharmakoresistenter, fokaler Temporallappenepilepsie mit Positronenemissionstomographie (PET). KLIN NEUROPHYSIOL 2002. [DOI: 10.1055/s-2002-34827] [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: 10/27/2022]
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Abstract
Competing labelling of solvent dimethyl sulfoxide (DMSO) can occur during the 11C-methylation of amine precursors. A kinetic analysis of the methylation reaction of DMSO with n.c.a. [11C]CH3I was performed at 120 degrees C resulting in rate constants. The rate constant for the formation of the intermediate, methylated DMSO ([11C]DMSO-M), is compared to the reaction of [11C]CH3I with two tertiary amines, namely Dexetimide and Desmethyloxotremorine-M. The specific activity of the labelled product is reduced due to partial 12C-methylation of the precursor amines by [11C]DMSO-M in cases of significant DMSO labelling as side reaction.
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Affiliation(s)
- A T Klein
- Institut für Nuklearchemie, Forschungszentrum Jülich GmbH, Germany
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Rossouw DD, Visser E, Coenen HH, Holschbach M. Radiosyntheses and radiochemical stability evaluation of various 123I-labelled organic prosthetic groups linked to model compounds. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.25804401337] [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: 11/12/2022]
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18
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Langen KJ, Bonnie R, Mühlensiepen H, Jansen P, Bröer S, Holschbach M, Coenen HH. 3-[123I]iodo-alpha-methyl-L-tyrosine transport and 4F2 antigen expression in human glioma cells. Nucl Med Biol 2001; 28:5-11. [PMID: 11182559 DOI: 10.1016/s0969-8051(00)00178-5] [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: 11/17/2022]
Abstract
3[(123)I]iodo-alpha-methyl-L-tyrosine is a tracer of amino acid transport in brain tumors using single-photon emission-computed tomography and predominantly transported by amino acid transport system L. The 4F2 antigen has been identified to be linked to system L-like transport and is assumed to be a part of the transporter protein. We demonstrated that system L-mediated transport of IMT and 4F2 antigen expression are dependent on proliferation rate of human glioma cells and significantly correlated with each other.
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Affiliation(s)
- K J Langen
- Institute of Medicine, Research Center Jülich GmbH, D-52425, Jülich, Germany.
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Langen KJ, Mühlensiepen H, Holschbach M, Hautzel H, Jansen P, Coenen HH. Transport mechanisms of 3-[123I]iodo-alpha-methyl-L-tyrosine in a human glioma cell line: comparison with [3H]methyl]-L-methionine. J Nucl Med 2000; 41:1250-5. [PMID: 10914918] [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: 02/17/2023] Open
Abstract
UNLABELLED The amino acid analog 3-[(123)I]iodo-alpha-methyl-L-tyrosine (IMT) is under clinical evaluation as a SPECT tracer of amino acid transport in brain tumors. This study investigated the carrier systems involved in IMT transport in human glioma cells in comparison with [3H-methyl]-L-methionine (3H-MET). METHODS Human glioma cells, type 86HG-39, were cultured and incubated for 1 min at 37 degrees C with IMT and 3H-MET in the lag phase (1.2 d after seeding), exponential growth phase (3 d after seeding), and plateau phase (8 d after seeding). Experiments were performed in the presence and absence of Na+, during inhibition of system L amino acid transport by 2-aminobicyclo[2.2.1 ]heptane-2-carboxylic acid (BCH), and during inhibition of system A amino acid transport by 2-(methylamino)-isobutyric acid (MeAIB). RESULTS IMT and 3H-MET uptake decreased by 55%-73% when the cells entered from the exponential growth phase into the plateau phase (P< 0.05; n = 3-11). Inhibition by BCH reduced uptake of IMT in the lag phase, exponential growth phase, and plateau phase by 90%-98% (P < 0.001; n = 3-6) and the uptake of 3H-MET by 73%-83% (P < 0.001; n = 3-11). In a Na+-free medium 3H-MET uptake was reduced by 23%-33% (P < 0.05; n = 3-11), whereas IMT uptake was not significantly different. MeAIB showed no significant effect on IMT or 3H-MET uptake in either phase. CONCLUSION Transport of both IMT and 3H-MET depends on the proliferation rate of human glioma cells in vitro and is dominated by BCH-sensitive transport. These data indicate that system L is induced in rapidly proliferating glioma cells and is the main contributor to the uptake of both tracers. 3H-MET transport showed a minor Na+ dependency that was not attributable to system A. The similarity of transport mechanisms of both tracers emphasizes the clinical equivalence of IMT SPECT and (11)C-MET PET for the diagnostic evaluation of gliomas.
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Affiliation(s)
- K J Langen
- Institute of Medicine, Research Center Jülich, Germany
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Boy C, Klimke A, Holschbach M, Herzog H, Mühlensiepen H, Rota Kops E, Sonnenberg F, Gaebel W, Stöcklin G, Markstein R, Müller-Gärtner HW. Imaging dopamine D4 receptors in the living primate brain: a positron emission tomography study using the novel D1/D4 antagonist [11C]SDZ GLC 756. Synapse 1998; 30:341-50. [PMID: 9826226 DOI: 10.1002/(sici)1098-2396(199812)30:4<341::aid-syn1>3.0.co;2-6] [Citation(s) in RCA: 24] [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: 11/09/2022]
Abstract
The dopamine D4 receptor has lately attracted interest since it has been hypothesized to be involved in the pathogenesis and pharmacotherapy of neuropsychiatric diseases. The present study provides first in vivo evidence of dopamine D4 receptors in primate brain using a [11C]benzo[g]quinoline, the novel radioligand [11C]SDZ GLC 756 ([11C]GLC: in vitro dissociation constants at human receptor clones [nM]: 1.10 at D1; 0.40 at D2; 25 at D3; 0.18 at D4.2; 6.03 at D5). Dynamic positron emission tomography scans were performed on healthy baboons (Papio hamadryas, n = 3). Specific receptor binding (SB) was calculated for striatum and neocortex (frontal, temporal, parietal, and occipital) based on the differences between the regional and the cerebellar concentration of [11C]. Blockade of D1 and D5 receptors by SCH23390 (1.7 pmol/kg) diminished SB in the striatum by 55 +/- 4% (mean +/- standard deviation, P < 0.05) and in the frontal cortex by 13 +/- 8% (P < 0.05) when compared to SB in the unblocked state (SB(D1-D5)). In the presence of the dopamine antagonists SCH23390 (1.7 micromol/kg) and raclopride (5.7 pmol/kg)--which mask the D1, D2, D3, and D5 subtypes--SB of [11C]GLC to D4 receptors (SB(D4)) was demonstrated in the striatum and all cortical regions of interest. In the striatum, the ratio of SB(D4)/SB(D1-D5) was 0.13 +/- 0.07. In the neocortex, SB(D4)/SB(D1-D5) was notably higher (0.77 +/- 0.29; mean of all cortical regions of interest). The widespread distribution of dopamine D4 receptors suggests a basic functional role of this receptor subtype in the modulation of cortical and subcortical neuronal activity.
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Affiliation(s)
- C Boy
- Institute of Medicine, Research Center Jülich, Germany
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Weckesser M, Fixmann A, Holschbach M, Müller-Gärtner HW. Influence of acetylcholine on binding of 4-[125I]iododexetimide to muscarinic brain receptors. Nucl Med Biol 1998; 25:777-80. [PMID: 9863566 DOI: 10.1016/s0969-8051(98)00039-0] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The distribution of nicotinic and muscarinic cholinergic receptors in the human brain in vivo has been successfully characterized using radiolabeled tracers and emission tomography. The effect of acetylcholine release into the synaptic cleft on receptor binding of these tracers has not yet been investigated. The present study examined the influence of acetylcholine on binding of 4-[125I]iododexetimide to muscarinic cholinergic receptors of porcine brain synaptosomes in vitro. 4-Iododexetimide is a subtype-unspecific muscarinic receptor antagonist with high affinity. Acetylcholine competed with 4-[125I]iododexetimide in a dose-dependent manner. A concentration of 500 microM acetylcholine inhibited 50% of total specific 4-[125I]iododexetimide binding to synaptosomes when both substances were given simultaneously. An 800 microM acetylcholine solution reduced total specific 4-[125I]iododexetimide binding by about 35%, when acetylcholine was given 60 min after incubation of synaptosomes with 4-[125I]iododexetimide. Variations in the synaptic acetylcholine concentration might influence muscarinic cholinergic receptor imaging in vivo using 4-[123I]iododexetimide. Conversely, 4-[123I]iododexetimide might be an appropriate molecule to investigate alterations of acetylcholine release into the synaptic cleft in vivo using single photon emission computed tomography.
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Affiliation(s)
- M Weckesser
- Institute of Medicine, Research Center Jülich, Germany.
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Langen KJ, Clauss RP, Holschbach M, Mühlensiepen H, Kiwit JC, Zilles K, Coenen HH, Müller-Gärtner HW. Comparison of iodotyrosines and methionine uptake in a rat glioma model. J Nucl Med 1998; 39:1596-9. [PMID: 9744350] [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: 02/08/2023] Open
Abstract
UNLABELLED This study compares brain tumor imaging with 3-[123I]iodo-alpha-methyl-L-tyrosine (IMT) and 3-[123I/125I]iodo-O-methyl-alpha-methyl-L-tyrosine (OMIMT) to that with [methyl-3H]-L-methionine (Met) in a rat glioma model by double-tracer autoradiography. METHODS Cells of the glioma clone F-98 were implanted stereotactically into the right basal ganglia of 22 Fischer 344 rats. After 8 days of tumor growth, the animals simultaneously were injected with a mixture of either 123I-IMT and 3H-Met (n=5), 123I-OMIMT and 3H-Met (n=8) or 123I-IMT and 125I-OMIMT (n=9). The animals were killed 15 min after the tracer injection and cryosections of the tumor-bearing brain area were exposed to phosphor-imaging plates both immediately and after the decay of 123I. Tumor-to-brain ratios (T/B) and intratumoral distribution of the different tracers and of the cresyl violet staining of the tissue were compared. RESULTS There was a significant correlation of the T/B ratios between all tracers (IMT versus Met: r=0.97, n=5, p < 0.01; OMIMT versus Met: r=0.94, n=8, p < 0.001; OMIMT versus IMT: r=0.95, n=9, p < 0.001). Intratumoral tracer distribution was similar for all tracers and the extent of tumor labeling was identical to that of the histological tumor extent. Mean values of the T/B ratios, however, were lower for IMT (2.81+/-0.78, n=14, mean+/-s.d., p < 0.01 compared with Met) and for OMIMT (2.03+/-0.57, n=17, p < 0.01 compared with Met) than for Met (3.86+/-1.12, n=13). CONCLUSION This study confirms that tumor imaging with IMT is similar to that of Met but T/B ratios of IMT are lower. OMIMT intratumoral tracer distribution and tumor size are similar to Met and IMT, but the T/B contrast is rather low and makes this amino acid less suitable for clinical application.
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Affiliation(s)
- K J Langen
- Institute of Medicine, Research Center Jülich, Germany
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Herzog H, Boy C, Schuth G, Holschbach M, Klimke A, Gaebel W, Müller-Gärtner HW. Kinetic Analysis of the D4-Receptor Ligand 11C-SDZ GLC 756. Neuroimage 1998. [DOI: 10.1016/s1053-8119(18)31885-8] [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: 12/01/2022] Open
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25
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Boy C, Holschbach M, Mühlensiepen H, Herzog H, Shah J, Olsson R, Coenen H, Müller-Gärtner HW. A1-Adenosine Receptor (A1AR) Mapping in Primate Brain Using the Novel A1AR-Antagonist [18F]CPFPX. Neuroimage 1998. [DOI: 10.1016/s1053-8119(18)31908-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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26
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Boy C, Klimke A, Holschbach M, Herzog H, Gaebel W, Eickhoff M, Beu M, Markstein R, Coenen H, Müller-Gärtner HW. Imaging Dopamine Receptors in Schizophrenia: PET – Studies Using the Novel Dopamine D4 – Antagonist [11C]SDZ GLC 756. Neuroimage 1998. [DOI: 10.1016/s1053-8119(18)31911-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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27
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Weckesser M, Griessmeier M, Schmidt D, Sonnenberg F, Ziemons K, Kemna L, Holschbach M, Langen K, Müller-Gärtner H. Iodine-123 alpha-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent. Eur J Nucl Med 1998; 25:150-6. [PMID: 9473263 DOI: 10.1007/s002590050208] [Citation(s) in RCA: 11] [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] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Single-photon emission tomography (SPET) with the amino acid analogue l-3-[123I]iodo-alpha-methyl tyrosine (IMT) is helpful in the diagnosis and monitoring of cerebral gliomas. Radiolabelled amino acids seem to reflect tumour infiltration more specifically than conventional methods like magnetic resonance imaging and computed tomography. Automatic tumour delineation based on maximal tumour uptake may cause an overestimation of mean tumour uptake and an underestimation of tumour extension in tumours with circumscribed peaks. The aim of this study was to develop a program for tumour delineation and calculation of mean tumour uptake which takes into account the mean background activity and is thus optimised to the problem of tumour definition in IMT SPET. Using the frequency distribution of pixel intensities of the tomograms a program was developed which automatically detects a reference brain region and draws an isocontour region around the tumour taking into account mean brain radioactivity. Tumour area and tumour/brain ratios were calculated. A three-compartment phantom was simulated to test the program. The program was applied to IMT SPET studies of 20 patients with cerebral gliomas and was compared to the results of manual analysis by three different investigators. Activity ratios and chamber extension of the phantom were correctly calculated by the automatic analysis. A method based on image maxima alone failed to determine chamber extension correctly. Manual region of interest analysis in patient studies resulted in a mean inter-observer standard deviation of 8.7% +/ -6.1% (range 2.7% -25.0%). The mean value of the results of the manual analysis showed a significant correlation to the results of the automatic analysis (r = 0.91, P<0. 0001 for the uptake ratio; r = 0.87, P<0.0001 for the tumour area). We conclude that the algorithm proposed simplifies the calculation of uptake ratios and may be used for observer-independent evaluation of IMT SPET studies. Three-dimensional tumour recognition and transfer to co-registered morphological images based on this program may be useful for the planning of surgical and radiation treatment.
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Affiliation(s)
- M Weckesser
- Institute of Medicine, Research Centre Jülich, Germany
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28
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Klimke A, Boy C, Eickhoff M, Herzog H, Holschbach M, Mühlensiepen H, Weckessec M, Rota-Kops E, Sonnenberg F, Gaebel W, Markstein R, Stöcklin G, Coenen H, Müller-Gärtner H. Dopamine D 1 and D 4-like receptors in untreated schizophrenic patients and healthy controls. Eur Psychiatry 1998. [DOI: 10.1016/s0924-9338(99)80289-2] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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29
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Schmidt D, Langen KJ, Herzog H, Wirths J, Holschbach M, Kiwit JC, Ziemons K, Coenen HH, Müller-Gärtner H. Whole-body kinetics and dosimetry of L-3--123I-iodo-alpha-methyltyrosine. Eur J Nucl Med 1997; 24:1162-6. [PMID: 9283111 DOI: 10.1007/bf01254250] [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: 02/05/2023]
Abstract
The synthetic amino acid L-3--123I-iodo-alpha-methyltyrosine (IMT) is currently under clinical evaluation as a single-photon emission tomography (SPET) tracer of amino acid uptake in brain tumours. So far, dosimetric data in respect of IMT are not available. Therefore we investigated the whole-body distribution of IMT in six patients with cerebral gliomas and the radiation doses were estimated. Whole-body scans were acquired at 1.5, 3 and 5 h after i.v. injection of 370-550 MBq IMT. The bladder was voided prior to each scan and the radioactivity excreted in the urine was measured. Based on the MIRD-11 method and the updated MIRDOSE3, the mean absorbed doses for various organs and the effective dose were calculated from geometric means of the anterior and posterior whole-body scans using seven source organs and the residence time. IMT was predominantly excreted by the kidneys (52.8%+/-11.5% at 1.5 h p.i., 63.0%+/-15.7% at 3 h p.i. and 74.6%+/-9.8% at 5 h p.i.). No organ system other than the urinary tract showed significant retention of the tracer. Early whole-body scans revealed slightly increased tracer uptake in the liver and in the bowel. Highest absorbed doses were found for the urinary bladder wall (0.047 mGy/MBq), the kidneys (0.010 mGy/MBq), the lower large intestinal wall (0.011 mGy/MBq) and the upper large intestinal wall (0.008 mGy/MBq). The effective dose according to ICRP 60 was estimated to be 0.0073 mSv/MBq for adults. This leads to an effective dose of 3.65 mSv in a typical brain SPET study using 500 MBq IMT. The MIRDOSE3 scheme yielded similar results. Thus, in spite of the relatively high tracer dose required for optimal brain scanning, radiation exposure in SPET studies with IMT is in the normal range of routine nuclear medicine investigations.
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Affiliation(s)
- D Schmidt
- Institute of Medicine, Research Center Jülich, Jülich, Germany
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Weckesser M, Hufnagel A, Ziemons K, Griessmeier M, Sonnenberg F, Hackländer T, Langen KJ, Holschbach M, Elger CE, Müller-Gärtner H. Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy. Eur J Nucl Med 1997; 24:1156-61. [PMID: 9283110 DOI: 10.1007/bf01254249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Animal experiments and preliminary results in humans have indicated alterations of hippocampal muscarinic acetylcholine receptors (mAChR) in temporal lobe epilepsy. Patients with temporal lobe epilepsy often present with a reduction in hippocampal volume. The aim of this study was to investigate the influence of hippocampal atrophy on the quantification of mAChR with single photon emission tomography (SPET) in patients with temporal lobe epilepsy. Cerebral uptake of the muscarinic cholinergic antagonist [123I]4-iododexetimide (IDex) was investigated by SPET in patients suffering from temporal lobe epilepsy of unilateral (n=6) or predominantly unilateral (n=1) onset. Regions of interest were drawn on co-registered magnetic resonance images. Hippocampal volume was determined in these regions and was used to correct the SPET results for partial volume effects. A ratio of hippocampal IDex binding on the affected side to that on the unaffected side was used to detect changes in muscarinic cholinergic receptor density. Before partial volume correction a decrease in hippocampal IDex binding on the focus side was found in each patient. After partial volume no convincing differences remained. Our results indicate that the reduction in hippocampal IDex binding in patients with epilepsy is due to a decrease in hippocampal volume rather than to a decrease in receptor concentration.
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Affiliation(s)
- M Weckesser
- Institute of Medicine, Research Centre Jülich, Germany
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Holschbach M, Hamkens W, Steinbach A, Hamacher K, Stöcklin G. [13N]Cisplatin: a fast and efficient on-line synthesis using a solid state support. Appl Radiat Isot 1997. [DOI: 10.1016/s0969-8043(96)00323-5] [Citation(s) in RCA: 12] [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: 11/24/2022]
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32
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Feinendegen DL, Ohlenschlaeger U, Grossmann K, Holschbach M, Shreeve WW, Feinendegen LE. Lipid metabolism in the liver studied in vivo with two isomers of labeled fatty acid analogs. J Nucl Med 1996; 37:1841-5. [PMID: 8917189] [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: 02/03/2023] Open
Abstract
UNLABELLED The two radioiodinated fatty acid analogs 15-(para-131 I-phenylpentadecanoic acid (pPPA) and 15-(ortho-131I-phenyl)-pentadecanoic acid (oPPA) are isomers with individually different routes in lipid metabolism but with near equal transport kinetics into tissue. METHODS Normal adult male Wistar rats (n = 79) and those with liver cell damage from adriamycin treatment (n = 84) received 1.48- 1.85 MBq 131I-pPPA or 131I-oPPA (specific activity, 33.3-46.3 GBq/microM) into the jugular vein. At 1, 2, 3, 5, 7, 10 and 20 min, livers of up to five animals per group were examined for total tracer uptake and tracer incorporation into various lipid fractions. RESULTS Uptake of both isomers into the total liver plateaued at about 2 min; the ratio oPPA/pPPA in normal liver averaged 2.63 and was significantly higher than the average ratio of 1.50 after adriamycin treatment. This fall in ratio was mainly due to an increase of pPPA uptake. Significant differences of the respective ratios were found in the plateau for the phospholipids (9.7 versus 3.0), cholesterol (2.4 versus 0.7) and triglycerides (2.0 versus 0.4). CONCLUSION The dual-tracer technique with pPPA and oPPA promises to be clinically useful for the diagnosis of liver disease by imaging the ratios of tracer uptake in the total liver and by in vitro analysis of the uptake ratio in serum triglycerides.
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Affiliation(s)
- D L Feinendegen
- Institute of Medicine and Chemistry, Research Center Juelich, Germany
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Krummeich C, Holschbach M. Kit preparation of n.c.a. 3-[123I]Iodo-l-α-methyltyrosine [123I]IMT, [123I]OMIT and [123I]OMIMT using Sep-Pak™ C-18 cartridges. Appl Radiat Isot 1995. [DOI: 10.1016/0969-8043(95)93109-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bender D, Holschbach M, Stöcklin G. Synthesis of n.c.a. carbon-11 labelled clozapine and its major metabolite clozapine-N-oxide and comparison of their biodistribution in mice. Nucl Med Biol 1994; 21:921-5. [PMID: 9234345 DOI: 10.1016/0969-8051(94)90080-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
N.c.a. [11C]clozapine, [8-chloro-11-(4-[methyl-11C]-methyl-1-piperazinyl)-5H-dibenzo[b,e]-1, 4-diazepine], 1, an atypical neuroleptic was synthesized by N-methylation of the desmethyl compound norclozapine, 3, using [11C]methyl iodide or [11C]methyl triflate for comparison. Subsequent oxidation of 1 with m-chloroperoxybenzoic acid yielded clozapine-N-oxide, 2, the major metabolite of 1. Purification of both radiolabelled products was carried out using a combined semi-preparative HPLC/solid phase extraction procedure. In preparative scale runs overall radiochemical yields for 1 and 2 were 70 and 65%, respectively. The radiochemical purities of both compounds exceeded 98% and the specific activities were in the range of 92-130 GBq/mumol (2.5-3.5 Ci/mumol). Biodistribution of 1 and 2 has been studied in NMRI mice. 10 min p.i. clozapine shows a 24-fold higher brain uptake than its major metabolite. At 60 min p.i., however, the cerebral uptake of both compounds is almost identical.
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Affiliation(s)
- D Bender
- Institut für Nuklearchemie, Forschungszentrum Jülich GmbH, Germany
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Krummeich C, Holschbach M, Stöcklin G. Direct n.c.a. electrophilic radioiodination of tyrosine analogues; their in vivo stability and brain-uptake in mice. Appl Radiat Isot 1994; 45:929-35. [PMID: 7951181 DOI: 10.1016/0969-8043(94)90230-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [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: 01/28/2023]
Abstract
In order to improve tracers for amino acid transport studies with SPET we have radioiodinated methylated tyrosines and compared their brain uptake and in vivo deiodination in mice. O-methylation not only leads to a higher lipophilicity and hence significantly higher brain uptake with a maximum of 5% dose/g for 3-[123I]iodo-O-methyl-L-alpha-methyltyrosine (OMIMT) but also significantly prevents in vivo deiodination. High n.c.a. radioiodination yields (> or = 80%) are obtained for the activated aromatic compounds L-tyrosine and L-alpha-methyltyrosine using Iodo-gen iin a heterogeneous aqueous system. Direct n.c.a. radioiodination of the less-activated O-methyl analogues has been achieved in reasonable yields (60%) with Iodo-gen in homogeneous TFA solutions containing about 10% of water.
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Affiliation(s)
- C Krummeich
- Institut für Nuklearchemie, Forschungszentrum Jülich GmbH, Germany
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37
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Henrich MM, Grossmann K, Motz W, Vogt M, Vester E, Holschbach M, Hamkens W, Notohamiprodjo G, Strauer BE, Feinendegen LE. Beta-oxidation of 1-[14C]-17-[131I]-iodo-heptadecanoic acid following intracoronary injection in humans results in similar release of both tracers. Eur J Nucl Med 1993; 20:225-30. [PMID: 8462611 DOI: 10.1007/bf00170003] [Citation(s) in RCA: 4] [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] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Radioiodine labelled 17-iodo-heptadecanoic acid (IHA) is used for non-invasive study of myocardial metabolism in coronary heart disease and cardiomyopathy. Yet in the interpretation of in vivo myocardial tracer kinetics, it is controversial whether the intracellular degradation of IHA or the removal of iodide across cellular membranes is the rate-limiting step in iodide release from the myocardium. In five patients undergoing coronary sinus catheterization, a mixture of about 40 kBq of [123I] NaI was injected into the left coronary artery. During the following 15-min period, frequent blood samples were taken from the aorta and the coronary sinus. In the aqueous phase of the venous blood, 14CO2 and inorganic 131I appeared nearly in parallel, with a peak time of 4-5 min. Moreover, as shown by the AV difference, there was no significant back diffusion of IHA and no significant non-specific deiodination detectable over the period of observation. There was myocardial retention of inorganic iodide (123I) injected into the left coronary artery. The data strongly support the premise that lipid turnover through beta-oxidation is the rate-limiting step in the externally measured release of iodide after IHA injection, provided that recirculating inorganic radioactive iodide is corrected for. In addition, 15 volunteers were studied using [11C]palmitic acid and [123I]IHA using PET and dynamic planar camera scintigraphy with iodide correction. There was no significant difference between the mean values of the elimination half-times, and also no significant correlation between half-times of both fatty acids for single individuals.
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Affiliation(s)
- M M Henrich
- Institute of Medicine, Research Center Jülich, Federal Republic of Germany
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Holschbach M, Rüden H, Pape HD, Thofern E. [The permeability for microorganisms of sterile packaging materials]. Dtsch Zahnarztl Z 1976; 31:631-4. [PMID: 782847] [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: 12/24/2022]
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Pape HD, Hörster W, Holschbach M, Rinkens D. [Department for mouth and jaw surgery in the new hospital skyscraper at Cologne]. Zahnarztl Mitt 1974; 64:610-2. [PMID: 4528184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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