Central nervous system tumors related to gliomas are of neuroectodermal origin and cover about 30% of all primary brain tumors. Glioma is not susceptible to any therapy and surgical attack remains one of the main approaches to its treatment. Preoperative tumor imaging methods, such as positron emission tomography (PET), are currently used to distinguish malignant tissue to increase the accuracy of glioma removal. However, PET is lacking a specific visualization of cells possessing certain molecular markers. Here, we report an application of aptamers to enhancing specificity in imaging tumor cells bearing the epidermal growth factor receptor (EGFR). Glioblastoma is characterized by increased EGFR expression, as well as mutations of this receptor associated with active division, migration, and adhesion of tumor cells. Since 2021, EGFR has been included into the WHO classification of gliomas as a molecular genetic marker. To obtain conjugates of aptamers GR20 and GOL1-specific to EGFR, a 4-[18F]fluorobenzylazide radiotracer was used as a synthon. For the production of the synthon, a method of automatic synthesis on an Eckert & Ziegler research module was adapted and modified using spirocyclic iodonium ylide as a precursor. Conjugation of 4-[18F]fluorobenzylazide and alkyne-modified aptamers was carried out using Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) with/without the TBTA ligand. As a result, it was possible to obtain 18F-labelled conjugates with 97% radiochemical purity for [18F]FB-GR20 and 98% for [18F]FB-GOL1. The obtained conjugates can be used for further studies in PET analysis on model animals with grafted glioblastoma.
Oxygen metabolism is a key factor in the life of a living organism. The article is the first part of a review of methods for measuring oxygen metabolism.Purpose. The aim of this review is to present an insight into the evolution of methods for measuring oxygen metabolism in a way from global to local measurement of brain perfusion. The role of the 15O isotope as the “gold standard” for measuring oxygen metabolism using positron emission tomography (PET) is described. We also provide a case report of brain tumor perfusion measurements from our clinic.Materials and methods. More than 200 Pubmed publications were studied with the keywords “positron emission tomography + O-15”. Relevant publications that do not contain these keywords or contain them in a different wording were also analyzed. A clinical case of a brain tumor perfusion using CT perfusion, MR-ASL and PET with H215O is provided.Results. The evolution of methods for measuring perfusion, oxygen extraction, and oxygen metabolism, is described. More than 50 papers are cited depicting key advances in measurement technologies. Examples of the use of PET with H215O in fundamental research and clinical practice are given.Conclusion. The obvious value of oxygen-isotope PET data is combined with the invasiveness (in some cases), technical complexity and high cost of the procedure. The second part of the review will be devoted to alternative methods for measuring oxygen metabolism, which are developing in the 21st century and which are intended for wide clinical use.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.