BACKGROUND: Prostate specific membrane antigen (PSMA) is a type II membrane protein widely expressed on the surface of prostate cancer cells. One of its functions is to act as a receptor mediating the ligand internalization. This PSMA property is employed in the diagnostics and therapy of prostate cancer. Over the years, small molecules with high affinity for PSMA have been developed and labelled with positron emitters (e.g. 68Ga, 18F, 11C, 64Cu, or 86Y). One of these radiolabelled ligands, [68Ga] PSMA-11, is one of the most widespread tracers for PET imaging of the prostate cancer. Many techniques have been proposed and tested for the 68Ga labelling of PSMA-11. The aim of our work was to design a labelling method of PSMA-11 that minimizes number of the used chemicals and steps, providing quantitative labelling yield at laboratory temperature and may be easily automated. METHODOLOGY: A68Ge/68Ga generator eluate in 0.1 M HCl was loaded on an activated Oasis MCX cartridge, and the cartridge was then thoroughly washed with water. The radionuclide 68Ga was eluted from the cartridge with 0.1 M NaHCO3 (pH = 8.5, n = 36) or with the same solution with pH adjusted to 7.2-9.0 (n = 38). Precursor PSMA-11 was mixed directly with the cartridge eluate of 68Ga in 0.1 M NaHCO3 of given pH. For the stability test, samples of 68GaPSMA-11 in 0.1 M NaHCO3 (pH 8.5) were mixed in ratio 1 : 1 with the following solutions: 0.1 M NaHCO3 (pH 8.5), human serum, PBS and 0.9% NaCl. In order to estimate an effect of the time elapsed between 68Ga elution from the cartridge in 0.1 M NaHCO3 (pH 8.5) and the labelling onset of PSMA-11, the latter was initiated 0, 5, 10 and 20 min post elution and radiochemical yield was monitored. All the PSMA-11 labelled samples were subjected to radiochemical purity test using HPLC. The whole process starting from generator elution up to HPLC analysis commencement took 10-15 min. RESULTS: Recovery of 68Ga from cartridge Oasis MCX using 0.1 M NaHCO3 at pH 8.5 was 71.5 ± 1.4%. Thirty six PSMA-11 samples (10 μg in reaction mixture) were labelled at pH 8.5 with total average radiochemical yield of 98 ± 2%. Recovery of 68Ga from cartridge Oasis MCX using 0.1 M NaHCO3 at variable pH of 7.2-9.0 was 62.5 ± 1.8% showing certain decrease with decreasing pH. A total of 138 samples of PSMA-11 were labelled with 68 Ga at variable pH (7.2-9.0) and four different amounts of PSMA-11 (1, 2.5, 5 and 10 μg) resulting in the labelling yields of 54.0 ± 5.3%, 88.2 ± 3.2%, 99.4 ± 0.3% and 99.9 ± 0.1%, respectively. Irrespective of the pH, the radiolabelling yield was quantitative for the molar ratio PSMA-11: 68Ga > 5000 : 1 in the reaction mixture. Stability tests in 0.1 M NaHCO3 (pH 8.5), human serum, PBS and 0.9% NaCl revealed no observable release of 68Ga from the 68Ga-PSMA-11 complex within 3 h. Similarly, the delay between the 68Ga elution from the Oasis MCX cartridge in 0.1 M NaHCO3 (pH 8.5) and start of the labelling of PSMA-11 labelling has no effect on the radiochemical yield. CONCLUSION: A new method of labelling PSMA-11 ligand with 68Ga in 0.1 M NaHCO3 using Oasis MCX cartridges was proposed, developed and tested. The results demonstrated that it is rapid, simple, reproducible and easy to automate.
- MeSH
- antigeny povrchové chemie MeSH
- chlornan sodný chemie MeSH
- glutamátkarboxypeptidasa II chemie MeSH
- lidé MeSH
- ligandy MeSH
- radioizotopy galia chemie MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Human carbonic anhydrase IX is a membrane enzyme that is significantly expressed in some types of cancer cells, while copper radioisotopes offer wide range of diagnostic, therapeutic and theranostic properties. The work was focused on a new approach to the labelling of antibody IgG M75 for epitope human carbonic anhydrase IX with copper radioisotopes 61Cu and 64Cu and its in vivo testing in mice with inoculated colorectal cancer. Monoclonal antibody IgG M75 for epitope human carbonic anhydrase IX was successfully conjugated with copper-specific chelator "phosphinate" and labelled with 61Cu and 64Cu The obtained molecule has considerable potential as a radioimmuno pharmaceutical suitable for imaging of tumours expressing carbonic anhydrase IX by positron emission tomography (PET).
- MeSH
- antigeny nádorové imunologie MeSH
- buňky HT-29 MeSH
- imunoglobulin G chemie MeSH
- imunokonjugáty chemie farmakokinetika MeSH
- karboanhydrasa IX imunologie MeSH
- kolorektální nádory diagnostické zobrazování enzymologie MeSH
- lidé MeSH
- monoklonální protilátky chemie farmakokinetika MeSH
- myši nahé MeSH
- myši MeSH
- pozitronová emisní tomografie MeSH
- radiofarmaka chemie farmakokinetika MeSH
- radioimunodetekce MeSH
- radioizotopy mědi chemie farmakokinetika MeSH
- tkáňová distribuce MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE: The purpose of this study was to evaluate a set of widely used nuclear medicine imaging agents as possible methods to study the early effects of systemic inflammation on the living brain in a mouse model of sepsis-associated encephalopathy (SAE). The lipopolysaccharide (LPS)-induced murine systemic inflammation model was selected as a model of SAE. PROCEDURES: C57BL/6 mice were used. A multimodal imaging protocol was carried out on each animal 4 h following the intravenous administration of LPS using the following tracers: [99mTc][2,2-dimethyl-3-[(3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(3E)-3-hydroxyiminobutan-2-yl]azanide ([99mTc]HMPAO) and ethyl-7-[125I]iodo-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylate ([125I]iomazenil) to measure brain perfusion and neuronal damage, respectively; 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) to measure cerebral glucose uptake. We assessed microglia activity on another group of mice using 2-[6-chloro-2-(4-[125I]iodophenyl)-imidazo[1,2-a]pyridin-3-yl]-N-ethyl-N-methyl-acetamide ([125I]CLINME). Radiotracer uptakes were measured in different brain regions and correlated. Microglia activity was also assessed using immunohistochemistry. Brain glutathione levels were measured to investigate oxidative stress. RESULTS: Significantly reduced perfusion values and significantly enhanced [18F]FDG and [125I]CLINME uptake was measured in the LPS-treated group. Following perfusion compensation, enhanced [125I]iomazenil uptake was measured in the LPS-treated group's hippocampus and cerebellum. In this group, both [18F]FDG and [125I]iomazenil uptake showed highly negative correlation to perfusion measured with ([99mTc]HMPAO uptake in all brain regions. No significant differences were detected in brain glutathione levels between the groups. The CD45 and P2Y12 double-labeling immunohistochemistry showed widespread microglia activation in the LPS-treated group. CONCLUSIONS: Our results suggest that [125I]CLINME and [99mTc]HMPAO SPECT can be used to detect microglia activation and brain hypoperfusion, respectively, in the early phase (4 h post injection) of systemic inflammation. We suspect that the enhancement of [18F]FDG and [125I]iomazenil uptake in the LPS-treated group does not necessarily reflect neural hypermetabolism and the lack of neuronal damage. They are most likely caused by processes emerging during neuroinflammation, e.g., microglia activation and/or immune cell infiltration.
- MeSH
- fluorodeoxyglukosa F18 farmakokinetika MeSH
- glukosa metabolismus MeSH
- jednofotonová emisní výpočetní tomografie metody MeSH
- lipopolysacharidy MeSH
- modely nemocí na zvířatech MeSH
- mozek diagnostické zobrazování metabolismus MeSH
- multimodální zobrazování metody MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- neurozobrazování metody MeSH
- nukleární lékařství metody MeSH
- pozitronová emisní tomografie metody MeSH
- radioaktivní indikátory * MeSH
- radioisotopová scintigrafie metody MeSH
- radioizotopy jodu farmakokinetika MeSH
- septická encefalopatie chemicky indukované diagnóza metabolismus patologie MeSH
- technecium 99mTc exametazim farmakokinetika MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
Úvod: Radioimunoterapie patří mezi rychle se rozvíjející klinické metody. Často je nejvhodnější možností terapie u pacientů s relabujícím lymfomem, případně u starších pacientů. Vývoj nových typů imunokonjugátů patří proto v posledních letech mezi klíčová témata ve vývoji radiofarmak. Metody: Imunoglobulin G M75 byl značen metodou elektrofilní jodace radionuklidem 125I, který je optimální pro vývoj metody značení a také pro stanovení vlastností značeného preparátu (vazebná aktivita, imunospecifita). Výhody 125I jsou zejména jeho dlouhý poločas (59,408 dne) a nízká radiační zátěž. Zachování vazby aktivního místa na antigen bylo testováno metodou ELISA, koncentrace byla stanovena modifikovanou metodou podle Bradfordové. Fyziologická distribuce byla testována na myších CD1-Foxn1nu. Výsledky: Stanovená kumulace značené protilátky v nádorové tkáni byla > 7 % podané radioaktivity, vazebná aktivita protilátky byla první den po značení vyšší než 90 % ve srovnání s vazebnou aktivitou neznačené protilátky. Závěr: Připravený radioimunokonjugát IgG M75 s 125I si zachovává dostatečnou schopnost vazby antigenu, a má proto potenciál v terapii tumorů exprimujících karbonátdehydratasu. Pro použití v radioterapii je třeba otestovat analogický radioimunokonjugát značený radionuklidem 131I.
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- Klíčová slova
- IgG M75 protilátky, CD1-Foxn1nu, radioimunokonjugát, elektrofilní jodace, chloramin-T, chloraminová metoda,
- MeSH
- chloraminy MeSH
- ELISA MeSH
- imunoglobulin G imunologie MeSH
- jodid sodný MeSH
- karboanhydrasy analýza imunologie MeSH
- kolorektální nádory radioterapie MeSH
- monoklonální protilátky * diagnostické užití MeSH
- myši MeSH
- protilátky nádorové analýza imunologie MeSH
- radioaktivita MeSH
- radiofarmaka * farmakokinetika chemická syntéza imunologie MeSH
- radioizotopy jodu * diagnostické užití imunologie MeSH
- tkáňová distribuce * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
