1
|
Villar M, Valiente M, Toscano M, Galmés M, González C, Ortiz M, Vega F, Oporto M, Bibiloni P, Chinchilla JL, Molina J, Ríos Á, Peña C, Rubí S. Development of a thin layer chromatography method for plasma correction of [ 18F]fluorocholine metabolites in positron emission tomography quantification studies in humans. Nucl Med Biol 2019; 74-75:34-40. [PMID: 31473490 DOI: 10.1016/j.nucmedbio.2019.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/05/2019] [Accepted: 08/19/2019] [Indexed: 11/27/2022]
Abstract
INTRODUCTION After its intravenous injection, [18F]fluorocholine is oxidized by choline-oxidase into its main plasma metabolite, [18F]fluorobetaine. If PET kinetic modeling quantification of [18F]fluorocholine uptake is intended, the plasma input time-activity-curve of the parent tracer must be obtained, i.e., the fraction of the total plasma radioactivity corresponding to the nonmetabolized [18F]fluorocholine at each time has to be known. Hence our aim was to develop an easy-routine Thin-Layer-Chromatography (TLC) method to separate and quantify the relative fractions of [18F]fluorocholine and [18F]fluorobetaine as a function of time during PET imaging in humans. METHODS First, we tested several combinations of solvents systems and layers to select the one showing the best resolution on non-radioactive standards. Thereafter, [18F]fluorobetaine was obtained through chemical oxidation of an [18F]fluorocholine sample at diferent incubation times and we applied the selected TLC-system to aliquots of this oxidation solution, both in a saline and in human deproteinized plasma matrices. The plates were detected by a radio-TLC-scanner. This TLC-system was finally applied to arterial plasma samples from 9 patients with high-grade-glioma undergoing brain PET imaging and a parent fraction curve was obtained in each of them. RESULTS A TLC-system based on Silica-Gel-60//MeOH-NH3 was selected from the choline/betaine non-radioactive standards assay. Radiochromatograms of [18F]fluorocholine oxidation solution yielded two separated and well-defined peaks, Rf = 0,03 ([18F]fluorocholine) and Rf = 0.78 (18F]fluorobetaine) consistent with those observed on non-radioactive standards. During the oxidation, the [18F]fluorocholine radioactivity peak decreased progressively at several incubation times, while the other peak ([18F]fluorobetaine) increased accordingly. The mean values of the parent fraction of [18F]fluorocholine of the 9 patients studied (mean+/-SD) were 94% ± 6%, 58% ± 15%, 43% ± 10%, 39% ± 6% and 37% ± 6% at 2.8 min, 5.8 min, 8.8 min, 11.7 min and 14.7 min post-injection, respectively. CONCLUSIONS We have developed a TLC-system, easy to perform in a standard radiopharmacy unit, that enables the metabolite correction of arterial input function of [18F]fluorocholine in patients undergoing PET oncologic quantitative imaging.
Collapse
Affiliation(s)
- Marina Villar
- Radiopharmacy Unit, Hospital Universitari Son Espases, Palma, Spain
| | - Manuel Valiente
- Radiopharmacy Unit, Hospital Universitari Son Espases, Palma, Spain
| | - María Toscano
- Radiopharmacy Unit, Hospital Universitari Son Espases, Palma, Spain
| | - Margalida Galmés
- Radiopharmacy Unit, Hospital Universitari Son Espases, Palma, Spain
| | - Carlos González
- SCOPIA Research Group, Universitat de les Illes Balears, Palma, Spain
| | - Marta Ortiz
- Department of Hospital Pharmacy, Hospital Universitari Son Espases, Palma, Spain
| | - Fernando Vega
- Radiopharmacy Unit, Hospital Universitari Son Espases, Palma, Spain
| | - Magdalena Oporto
- Department of Nuclear Medicine, Hospital Universitari Son Espases, Palma, Spain
| | - Pedro Bibiloni
- SCOPIA Research Group, Universitat de les Illes Balears, Palma, Spain
| | | | - Jesús Molina
- Department of Nuclear Medicine, Hospital Universitari Son Espases, Palma, Spain
| | - Ángel Ríos
- Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma, Spain
| | - Cristina Peña
- Department of Nuclear Medicine, Hospital Universitari Son Espases, Palma, Spain; Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma, Spain
| | - Sebastià Rubí
- Department of Nuclear Medicine, Hospital Universitari Son Espases, Palma, Spain; Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma, Spain.
| |
Collapse
|
2
|
Dixon SP, Pitfield ID, Perrett D. Comprehensive multi-dimensional liquid chromatographic separation in biomedical and pharmaceutical analysis: a review. Biomed Chromatogr 2006; 20:508-29. [PMID: 16779789 DOI: 10.1002/bmc.672] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
'Multi-dimensional' liquid separations have a history almost as long as chromatography. In multi-dimensional chromatography the sample is subjected to more than one separation mechanism; each mechanism is considered an independent separation dimension. The separations can be carried out either offline via fraction collection, or directly coupled online. Early multi-dimensional separations using combinations of paper chromatography, electrophoresis and gels, in both planar and columnar modes are reviewed. Developments in HPLC have increased the number of measurable analytes in ever more complex matrices, and this has led to the concept of 'global metabolite profiling'. This review focuses on the theory and practice of modern 'comprehensive' multi-dimensional liquid chromatography when applied to biomedical and pharmaceutical analysis.
Collapse
Affiliation(s)
- Steven P Dixon
- Bioanalytical Science (WHRI), Barts and The London, Queen Mary's School of Medicine and Dentistry, John Vane Science Centre, Charterhouse Square, UK.
| | | | | |
Collapse
|
3
|
Katz-Brull R, Koudinov AR, Degani H. Direct detection of brain acetylcholine synthesis by magnetic resonance spectroscopy. Brain Res 2005; 1048:202-10. [PMID: 15921662 DOI: 10.1016/j.brainres.2005.04.080] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 04/24/2005] [Accepted: 04/26/2005] [Indexed: 11/26/2022]
Abstract
The cholinergic system is an important modulatory neurotransmitter system in the brain. Changes in acetylcholine concentration have been previously determined directly in animal models and human brain biopsy specimens, and indirectly, by the effects of drugs, in living humans. Here, we developed a method for direct determination of acetylcholine synthesis in living brain tissue. The method is based on administration of choline, enriched with carbon-13 (stable isotope) in the two methylene positions, and detection of labeled acetylcholine and all other metabolic fates of choline, by carbon-13 magnetic resonance spectroscopy. We tested this method in rat brain slices and found it to be specific for acetylcholine synthesis in both the cortex and hippocampus. This method is potentially useful as a research tool for exploring the cholinergic system role in cognitive processes and memory storage as well as in diseases in which the malfunction of the cholinergic system has been implicated.
Collapse
Affiliation(s)
- Rachel Katz-Brull
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel.
| | | | | |
Collapse
|
4
|
Sasaki T, Kawamura K, Tanaka Y, Ando S, Senda M. Assessment of choline uptake for the synthesis and release of acetylcholine in brain slices by a dynamic autoradiographic technique using [11C]choline. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 2002; 10:1-11. [PMID: 12379431 DOI: 10.1016/s1385-299x(02)00159-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The uptake of choline for the synthesis and release of acetylcholine was investigated in brain slices by dynamic positron autoradiography using [11C]choline. Brain slices (330 microm) were incubated with [11C]choline in oxygenated Krebs-Ringer medium at 34 degrees C and serial two-dimensional time-resolved images of the uptake and release of radioactivity were recorded on Storage Phosphor screens. [11C]choline uptake increased with the period of incubation and was 1.9 times higher in the striatum than cerebral cortex. The uptake in the striatum was significantly diminished by hemicholinium-3 (HC-3), an inhibitor of high-affinity choline uptake. Pretreatment of brain slices with 50 mM K(+) for 20 min enhanced the uptake in striatum. The uptake of [11C]choline in brain slices was saturable using nonlabeled choline. Two uptake systems, a high-affinity and a low-affinity system, were confirmed to exist by kinetic analysis using Lineweaver-Burk plots. The 11C radioactivity that had accumulated in the striatum disappeared on treatment with veratridine, a depolarization agent, in the presence of HC-3. This pattern of disappearance was consistent with that of the appearance of unlabeled and labeled acetylcholine in the medium. These results indicate that this method is useful for obtaining information regarding the uptake of choline for the synthesis and release of acetylcholine in live brain tissues.
Collapse
Affiliation(s)
- Toru Sasaki
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan.
| | | | | | | | | |
Collapse
|