The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Pierre Bohn - One of the best experts on this subject based on the ideXlab platform.
-
synthesis and biological evaluation of a novel 99mtc labeled 2 Nitroimidazole Derivative as a potential agent for imaging tumor hypoxia
Bioorganic & Medicinal Chemistry Letters, 2013Co-Authors: Yoann Joyard, Vadim Le Joncour, Helene Castel, Cherif Bounana Diouf, Laurent Bischoff, Cyril Papamicael, Vincent Levacher, Pierre Vera, Pierre BohnAbstract:Abstract Tumor hypoxia plays a major role in reducing the efficacy of therapeutic modalities like chemotherapy and radiation therapy in combating cancer. In order to target hypoxic tissues, a tripeptide ligand having a 2-Nitroimidazole moiety, as a bioreductive species, was synthesized. The latter was radiolabeled with 99m Tc for imaging hypoxic regions of tumors and was characterized by means of its rhenium analogue. The biodistribution and scintigraphic image of the corresponding 99m Tc-complex showed accumulation in tumor and these results suggest that it could be a marker for imaging tumor hypoxia.
-
Synthesis and biological evaluation of a novel (99m)Tc labeled 2-Nitroimidazole Derivative as a potential agent for imaging tumor hypoxia.
Bioorganic and Medicinal Chemistry Letters, 2013Co-Authors: Yoann Joyard, Vadim Le Joncour, Helene Castel, Cherif Bounana Diouf, Laurent Bischoff, Cyril Papamicael, Vincent Levacher, Pierre Vera, Pierre BohnAbstract:Tumor hypoxia plays a major role in reducing the efficacy of therapeutic modalities like chemotherapy and radiation therapy in combating cancer. In order to target hypoxic tissues, a tripeptide ligand having a 2-Nitroimidazole moiety, as a bioreductive species, was synthesized. The latter was radiolabeled with (99m)Tc for imaging hypoxic regions of tumors and was characterized by means of its rhenium analogue. The biodistribution and scintigraphic image of the corresponding (99m)Tc-complex showed accumulation in tumor and these results suggest that it could be a marker for imaging tumor hypoxia.
Juan A. Squella - One of the best experts on this subject based on the ideXlab platform.
-
Voltammetric Reduction of a 4‐Nitroimidazole Derivative on a Multiwalled Carbon Nanotubes Modified Glassy Carbon Electrode
Electroanalysis, 2008Co-Authors: Paola Jara-ulloa, Luis J. Núñez-vergara, Soledad Bollo, Juan A. SquellaAbstract:We report the electrochemical behavior of a 4-Nitroimidazole Derivative, 1-methyl-4-nitro-2-hydroxymethylimidazole (4-NImMeOH), on glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNT). As dispersing agents, dimethylformamide (DMF) and water were used. The electrochemical response of the resulting electrodes was evaluated using linear sweep, cyclic and square-wave voltammetry (LSV, CV and SWV). Several parameters such as medium pH, nature and concentration of the CNTs dispersion and accumulation time were tested. The optimal conditions determined for obtain better response were: pH 2, dispersion concentration=4 mg/mL of CNT in water, accumulation time=7 min. The MWCNT-modified GCE exhibited attractive electrochemical properties producing enhanced currents with a significant reduction in the overpotential and good signal-to-noise characteristics, in comparison with the bare GCE. The modified electrode is highly repeatable for consecutive measurements, reaching a variation coefficient of 2.9% for ten consecutive runs.
-
Micellar effects on the reduction of 4-Nitroimidazole Derivative: Detection and quantification of the nitroradical anion
Electroanalysis, 2007Co-Authors: Paola Jara-ulloa, Luis J. Núñez-vergara, Juan A. SquellaAbstract:The reductive electrochemistry of 1-methyl-4-nitro-2-hydroxymethylimidazole, a 4-Nitroimidazole Derivative, was examined in the presence of surfactants anionic as sodium dodecyl sulfate (SDS), nonionic, Triton-X, Cationic, Hyamine and Cetyl Trimethyl Ammonium Bromide (CTAB). The reductive mechanism of the Nitroimidazole Derivative was found to be dependent of both, nature and concentration of the surfactants.
-
Electrochemical reduction of 2-Nitroimidazole in aprotic medium: Influence of its dissociation equilibrium on the reduction mechanism
Electrochimica Acta, 2006Co-Authors: Juan A. Squella, A. Campero, J. J. Maraver, J. CarbajoAbstract:Abstract The electrochemical reduction of 2-Nitroimidazole in a non-aqueous medium using cyclic voltammetry (CV) at a mercury electrode was carried out. The 2-Nitroimidazole Derivative in DMF + 0.1 M tetra( n -butyl)ammonium hexafluorophosphate (TBAHFP6) resulted in the following dissociation equilibrium: HNRNO 2 ⇆ − NRNO 2 + H + The neutral species (HNRNO 2 ) and the corresponding conjugate base ( − NRNO 2 ) are characterized by UV absorption bands at 328 and 370 nm, respectively. The voltammograms of 2-Nitroimidazole produced two well-defined signals, which were determined by the above dissociation equilibrium. The first reduction peak was caused by the reduction of the neutral species according to the following overall mechanism: 5HNRNO 2 + 4e − → 4 − NRNO 2 + HNRNHOH + H 2 O The second quasi-reversible couple was caused by the reduction of the conjugate base according to the following equation: − NRNO 2 + e − → NRNO 2 −
Yoann Joyard - One of the best experts on this subject based on the ideXlab platform.
-
synthesis and biological evaluation of a novel 99mtc labeled 2 Nitroimidazole Derivative as a potential agent for imaging tumor hypoxia
Bioorganic & Medicinal Chemistry Letters, 2013Co-Authors: Yoann Joyard, Vadim Le Joncour, Helene Castel, Cherif Bounana Diouf, Laurent Bischoff, Cyril Papamicael, Vincent Levacher, Pierre Vera, Pierre BohnAbstract:Abstract Tumor hypoxia plays a major role in reducing the efficacy of therapeutic modalities like chemotherapy and radiation therapy in combating cancer. In order to target hypoxic tissues, a tripeptide ligand having a 2-Nitroimidazole moiety, as a bioreductive species, was synthesized. The latter was radiolabeled with 99m Tc for imaging hypoxic regions of tumors and was characterized by means of its rhenium analogue. The biodistribution and scintigraphic image of the corresponding 99m Tc-complex showed accumulation in tumor and these results suggest that it could be a marker for imaging tumor hypoxia.
-
Synthesis and biological evaluation of a novel (99m)Tc labeled 2-Nitroimidazole Derivative as a potential agent for imaging tumor hypoxia.
Bioorganic and Medicinal Chemistry Letters, 2013Co-Authors: Yoann Joyard, Vadim Le Joncour, Helene Castel, Cherif Bounana Diouf, Laurent Bischoff, Cyril Papamicael, Vincent Levacher, Pierre Vera, Pierre BohnAbstract:Tumor hypoxia plays a major role in reducing the efficacy of therapeutic modalities like chemotherapy and radiation therapy in combating cancer. In order to target hypoxic tissues, a tripeptide ligand having a 2-Nitroimidazole moiety, as a bioreductive species, was synthesized. The latter was radiolabeled with (99m)Tc for imaging hypoxic regions of tumors and was characterized by means of its rhenium analogue. The biodistribution and scintigraphic image of the corresponding (99m)Tc-complex showed accumulation in tumor and these results suggest that it could be a marker for imaging tumor hypoxia.
Xin-chen Sun - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and Preliminary Evaluation of a Novel 18F-Labeled 2-Nitroimidazole Derivative for Hypoxia Imaging
Frontiers in Oncology, 2021Co-Authors: Chi Zhang, Xi Yang, Xi-juan Yao, Qun Zhang, Xin-chen SunAbstract:ObjectiveHypoxia is prevalent in tumors and plays a pivotal role in resistance to chemoradiotherapy. 18F-MISO (18F-labeled fluoromisonidazole) is currently the preferred choice of PET hypoxia tracers in clinical practice, but has severe disadvantages involving complex labeling methods and low efficient imaging due to lipophilicity. We aimed to design a novel Nitroimidazole Derivative labeled by 18F via a chelation technique to detect hypoxic regions and provide a basis for planning radiotherapy.Materials and MethodsFirst, we synthesized a 2-Nitroimidazole precursor, 2-[4-(carboxymethyl)-7-[2-(2-(2-nitro-1H-imidazol-1-yl)acetamido)ethyl]-1,4,7-triazanonan-1-yl]acetic acid (NOTA-NI). For 18F-labeling, a 18F solution was reacted with a mixture of AlCl3 and NOTA-NI at pH 3.5 and 100°C for 20 min, and the radiochemical purity and stability were evaluated. Biological behaviors of Al18F-NOTA-NI were analyzed by an uptake study in ECA109 normoxic and hypoxic cells, and a biodistribution study and microPET imaging in ECA109 xenografted mice.ResultsAl18F-NOTA-NI required a straightforward and efficient labeling procedure compared with 18F-MISO. The uptake values were distinctly higher in hypoxic tumor cells. Animal studies revealed that the imaging agent was principally excreted via the kidneys. Due to hydrophilicity, the radioactivities in blood and muscle were decreased, and we could clearly distinguish xenografted tumors from para-carcinoma tissue by PET imaging.ConclusionsThe Nitroimidazole tracer Al18F-NOTA-NI steadily accumulated in hypoxic areas in tumors and was rapidly eliminated from normal tissue. It appears to be a promising candidate for hypoxia imaging with high sensitivity and resolution.
-
synthesis and preliminary evaluation of a novel 18f labeled 2 Nitroimidazole Derivative for hypoxia imaging
Frontiers in Oncology, 2021Co-Authors: Chi Zhang, Xi Yang, Xi-juan Yao, Qun Zhang, Xin-chen SunAbstract:Objective: Hypoxia is prevalent in tumors and plays a pivotal role in resistance to chemoradiotherapy. 18F-MISO is currently the preferred choice of PET hypoxia tracers in clinical practice, but has severe disadvantages involving complex labeling methods and low efficient imaging due to lipophilicity. We aimed to design a novel Nitroimidazole Derivative labeled by 18F via a chelation technique to detect hypoxic regions and provide a basis for planning radiotherapy. Materials and Methods: First, we synthesized a 2-Nitroimidazole precursor, 2-[4-(carboxymethyl)-7-[2-(2-(2-nitro-1H-imidazol-1-yl)acetamido)ethyl]-1,4,7-triazanonan-1-yl]acetic acid (NOTA-NI). For 18F-labeling, a 18F solution was reacted with a mixture of AlCl3 and NOTA-NI at pH 3.5 and 100 °C for 20 min, and the radiochemical purity and stability were evaluated. Biological behaviors of Al18F-NOTA-NI were analyzed by an uptake study in ECA109 normoxic and hypoxic cells, and a biodistribution study and microPET imaging in ECA109 xenografted mice. Results: Al18F-NOTA-NI required a straightforward and efficient labeling procedure compared with 18F-MISO. The uptake values were distinctly higher in hypoxic tumor cells. Animal studies revealed that the imaging agent was principally excreted via the kidneys. Due to hydrophilicity, the radioactivities in blood and muscle were decreased, and we could clearly distinguish xenografted tumors from para-carcinoma tissue by PET imaging. Conclusions: The Nitroimidazole tracer Al18F-NOTA-NI steadily accumulated in hypoxic areas in tumors and was rapidly eliminated from normal tissue. It appears to be a promising candidate for hypoxia imaging with high sensitivity and resolution.
V. Gregoire - One of the best experts on this subject based on the ideXlab platform.
-
Preclinical validation of the hypoxia tracer 2-(2-nitroimidazol-1-yl)-N-(3,3,3-[^18F]trifluoropropyl)acetamide, [^18F]EF3
European Journal of Nuclear Medicine and Molecular Imaging, 2004Co-Authors: P. Mahy, M. De Bast, P. H. Leveque, J. Gillart, D. Labar, J. Marchand, V. GregoireAbstract:The 2-Nitroimidazole Derivative 2-(2-nitroimidazol-1-yl)- N -(3,3,3-trifluoropropyl)acetamide (EF3) is a marker which forms adducts into hypoxic cells. Radiosynthesis of [^18F]EF3 was recently performed by our group. Our aim was to study the pharmacokinetics, biodistribution, metabolism and specificity for hypoxia of [^18F]EF3. MCa-4, SCC VII, NFSA, FSA, FSA II or Sa-NH tumour-bearing C3H mice were injected intravenously with [^18F]EF3 and allowed to breathe air, 10% O_2 or carbogen until sacrifice 5–770 min after injection. Radioactivity was measured ex vivo in various organs, including urine and faeces. Selected organs were additionally processed to measure tracer metabolites with high-performance liquid chromatography. The half-life in blood was 73.9 min. [^18F]EF3 was eliminated mainly via the kidneys, with 75% of the injected activity found in the urine by 12 h 50 min. The biodistribution was fast and homogeneous except in the brain and the bone, where it was significantly lower, and in the liver and the kidney, where it was significantly higher. In most organs, the exceptions being the gastrointestinal and urinary tract, tissue-to-blood ratios were below or close to unity. In tumours, a relative accumulation of the tracer was observed with time, which, at 220 min after injection, depended on tumour strain and oxygenation conditions, i.e. 10% O_2 significantly increased the tumour-to-muscle ratio whereas carbogen decreased it. [^18F]EF3 was rapidly metabolised in the kidney and the liver. [^18F]EF3 is a promising tracer for detection of tumour hypoxia. A phase I study in head and neck cancer patients is in progress at our institution.