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Radiolabeled Compounds (radiolabeled + compound)
Selected AbstractsThe [Tc(N)(PNP)]2+ metal fragment labeled cholecystokinin-8 (CCK8) peptide for CCK-2 receptors imaging: in vitro and in vivo studiesJOURNAL OF PEPTIDE SCIENCE, Issue 4 2007Stefania Agostini Abstract The radiolabeling of the natural octapeptide CCK8, derivatized with a cysteine residue (Cys-Gly-CCK8), by using the metal fragment [99mTc(N)(PNP3)]2+ (PNP3 = N,N -bis(dimethoxypropylphosphinoethyl)methoxyethylamine) is reported. The [99mTc(N)(NS-Cys-Gly-CCK8)(PNP3)]+ complex was obtained according to two methods (one-step or two-step procedure) that gave the desired compound in high yield. The complex is stable in aqueous solution and in phosphate buffer. In vitro challenge experiments with an excess of cysteine and glutathione indicate that no transchelation reactions occur, confirming the high thermodynamic stability and kinetic inertness of this compound. Stability studies carried out in human and mouse serum, as well as in mouse liver homogenates, show that the radiolabeled compound remains intact for prolonged incubation at 37 °C. Binding properties give Kd (19.0 ± 4.6 nmol/l) and Bmax (,106 sites/cell) values in A431 cells overexpressing the CCK2-R. In vivo evaluation of the compound shows rapid and specific targeting to CCK2-R, a fourfold higher accumulation compared to nonreceptor expressing tumors. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis and evaluation of two uncharged 99mTc-labeled derivatives of thioflavin-T as potential tracer agents for fibrillar brain amyloidJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 6 2009K. Serdons Abstract Thioflavin-T is a fluorescent dye for in vitro detection of fibrillar amyloid ,, a protein found in the brain of patients suffering from Alzheimer's disease. We synthesized and biologically evaluated two uncharged 99mTc-labeled derivatives of thioflavin-T. The precursors for labeling were synthesized by coupling an S,S, -bis-triphenylmethyl- N - tert -butoxycarbonyl bis-amino-bis-thiol tetradentate ligand via a propoxy spacer to 2-(4,-aminophenyl)-1,3-benzothiazole at the 6-position or the 2,-position. Deprotection and labeling with 99mTc were done via a one-pot procedure (15% yield) after which the labeled compound was isolated by high performance liquid chromatography (LC). LC in combination with mass spectrometry (MS) was used for identity confirmation of the labeled compounds. Results of electrophoresis and log,P determination supported the assumption that the radiolabeled compounds could cross the blood,brain barrier by passive diffusion. However, in normal mice both compounds showed a low brain uptake 2,min post injection. They were mainly excreted through the hepatobiliary system, with some accumulation in the stomach. Sixty minutes after intravenous injection, 37% of the 99mTc-activity in the blood corresponded to the original compound. In view of the low brain uptake, it is concluded that the studied 99mTc-labeled derivatives of thioflavin-T are not suitable as tracer agents for in vivo visualization of amyloid in brain. Copyright © 2009 John Wiley & Sons, Ltd. [source] Radiosynthesis of 3-[18F]fluoropropyl and 4-[18F]fluorobenzyl triarylphosphonium ionsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2004Hayden T. Ravert Abstract 3-[18F]Fluoropropyl-, 4-[18F]fluorobenzyl-triphenylphosphonium and 4-[18F]fluorobenzyltris-4-dimethylaminophenylphosphonium cations were synthesized in multi-step reactions from no carrier added (nca) [18F]fluoride. The time for synthesis, purification, and formulation was 56, 82, and 79 min with an average radiochemical yield of 12, 6 and 15%, respectively (not corrected for decay). The average specific radioactivity for the three radiolabeled compounds was 14.9 GB q/µmole (403 mCi/µmole) at end of synthesis (EOS). Copyright © 2004 John Wiley & Sons, Ltd. [source] In vitro transcorneal and transscleral diffusion of radiolabeled compounds in human and rabbit cornea and in human, monkey, dog, and rabbit scleraACTA OPHTHALMOLOGICA, Issue 2009CB STRUBLE Purpose To determine the in vitro diffusion of selected compounds across the cornea or sclera of humans, monkeys, dogs, and rabbits. Methods Human and NZW rabbit corneas were obtained and the epithelium was removed from one cornea of each pair. Corneas were mounted in chambers with 3H-water or 3H-dexamethasone on the epithelial side and BSS solution on the endothelial side. Serial aliquots were taken from each chamber and assayed by LSC. Scleral sections from human, NZW rabbit, dog, or monkey eyes were mounted in perfusion chambers. Adjacent sclera was used for H&E histology. 3H-water, 3H-dexamethasone, or 70kD-14C-dextran were added to the episcleral surface while perfusing BSS across the choroidal side. Serial aliquots were collected up to 5 hrs and assayed by LSC. Scleral permeability (ktrans) was calculated. H&E slides were used to determine scleral thickness. Results 3H-water diffused through cornea faster than 3H-dexamethasone, especially with denuded epithelium. Scleral thickness and molecular weight were determinant of diffusion in sclera. Monkey sclera was thinnest, followed by dog, rabbit, and human. ktrans for 70kD-14C-Dextran and 3H-dexamethasone were greatest in monkey, followed by dog, rabbit, and human. ktrans values for 3H-water were similar in all species, and greater than values for 14C-dextran and 3H-dexamethasone. Conclusion These studies demonstrate permeability of cornea and sclera in human and animal models with compounds of varied molecular weights representative of drugs being developed for treatment of ocular diseases. The results of this study indicate that these techniques are valuable as screening tools in the development of ocular drugs. [source] | ||||||||||