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The Chemistry of Phenylimidotechnetium(V) Complexes with Isocyanides: Steric and Electronic Factors.Molecules (Basel, Switzerland) Dec 2022Organometallic approaches are of ongoing interest for the development of novel functional Tc radiopharmaceuticals, while the basic organotechnetium chemistry seems...
Organometallic approaches are of ongoing interest for the development of novel functional Tc radiopharmaceuticals, while the basic organotechnetium chemistry seems frequently to be little explored. Thus, structural and reactivity studies with the long-lived isotope Tc are of permanent interest as the foundation for further progress in the related radiopharmaceutical research with this artificial element. Particularly the knowledge about the organometallic chemistry of high-valent technetium compounds is scarcely developed. Here, phenylimido complexes of technetium(V) with different isocyanides are introduced. They have been synthesized by ligand-exchange procedures starting from [Tc(NPh)Cl(PPh)]. Different reactivity patterns and products have been obtained depending on the steric and electronic properties of the individual ligands. This involves the formation of 1:1 and 1:2 exchange products of Tc(V) with the general formulae [Tc(NPh)Cl(PPh)(isocyanide)], - or -[Tc(NPh)Cl(isocyanide)], but also the reduction in the metal and the formation of cationic technetium(I) complex of the formula [Tc(isocyanide)] when p-fluorophenyl isocyanide is used. The products have been studied by single-crystal X-ray diffraction and spectroscopic methods, including IR and multinuclear NMR spectroscopy. DFT calculations on the different isocyanides allow the prediction of their reactivity towards electron-rich and electron-deficient metal centers by means of the empirical SADAP parameter, which has been derived from the potential energy surface of the electron density on their potentially coordinating carbon atoms.
Topics: Technetium; Cyanides; Radiopharmaceuticals; Crystallography, X-Ray; Ligands; Magnetic Resonance Spectroscopy; Metals
PubMed: 36500639
DOI: 10.3390/molecules27238546 -
Bioorganic & Medicinal Chemistry Letters Jan 2014The purpose of this study was to examine the biodistribution of (99m)Tc-RAD-Arg-(Arg(11))CCMSH in B16/F1 melanoma-bearing C57 mice to determine whether the replacement...
The purpose of this study was to examine the biodistribution of (99m)Tc-RAD-Arg-(Arg(11))CCMSH in B16/F1 melanoma-bearing C57 mice to determine whether the replacement of the Lys linker with an Arg linker could decrease the renal uptake of (99m)Tc-RAD-Arg-(Arg(11))CCMSH. (99m)Tc-RAD-Arg-(Arg(11))CCMSH exhibited rapid and high tumor uptake (17.98±4.96% ID/g at 2h post-injection) in B16/F1 melanoma-bearing C57 mice. As compared to (99m)Tc-RAD-Lys-(Arg(11))CCMSH, the replacement of the Lys linker with an Arg linker dramatically decreased the renal uptake of (99m)Tc-RAD-Arg-(Arg(11))CCMSH by 68%, 62%, 73% and 64% at 0.5, 2, 4 and 24h post-injection, respectively. Flank B16/F1 melanoma lesions were clearly imaged at 2h post-injection using (99m)Tc-RAD-Arg-(Arg(11))CCMSH as an imaging probe.
Topics: Animals; Kidney; Melanoma; Mice; Mice, Inbred C57BL; Molecular Structure; Oligopeptides; Technetium; Tissue Distribution; alpha-MSH
PubMed: 24316121
DOI: 10.1016/j.bmcl.2013.11.042 -
Cancer Reports (Hoboken, N.J.) Jan 2022The fluorescent dye indocyanine green (ICG) has emerged as a promising tracer for intraoperative detection of sentinel lymph nodes (SLNs) in early-stage cervical cancer.... (Comparative Study)
Comparative Study Meta-Analysis
BACKGROUND
The fluorescent dye indocyanine green (ICG) has emerged as a promising tracer for intraoperative detection of sentinel lymph nodes (SLNs) in early-stage cervical cancer. Although researchers suggest the SLN detection of ICG is equal to the more conventional combined approach of a radiotracer and blue dye, no consensus has been reached.
AIMS
We aimed to assess the differences in overall and bilateral SLN detection rates with ICG versus the combined approach, the radiotracer technetium-99m ( Tc) with blue dye.
METHODS AND RESULTS
We searched MEDLINE, Embase, and the Cochrane Library from inception to January 1, 2020 and included studies reporting on a comparison of SLN detection with ICG versus Tc with blue dye in early-stage cervical cancer. The overall and bilateral detection rates were pooled with random-effects meta-analyses. From 118 studies retrieved seven studies (one cross-sectional; six retrospective cohorts) were included, encompassing 589 patients. No significant differences were found in the pooled overall SLN detection rate of ICG versus Tc with blue dye. Meta-analyses of all studies showed ICG to result in a higher bilateral SLN detection rate than Tc with blue dye; 90.3% (95%CI, 79.8-100.0%) with ICG versus 73.5% (95%CI, 66.4-80.6%) with 99mTc with blue dye. This resulted in a significant and clinically relevant risk difference of 16.6% (95%CI, 5.3-28.0%). With sensitivity analysis, the risk difference of the bilateral detection rate maintained in favor of ICG but was no longer significant (13.2%, 95%CI -0.8-27.3%).
CONCLUSION
ICG appears to provide higher bilateral SLN detection rates compared to Tc with blue dye in patients with early-stage cervical cancer. However, in adherence with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, the quality of evidence is too low to provide strong recommendations and directly omit the combined approach of Tc with blue dye.
Topics: Female; Humans; Indocyanine Green; Predictive Value of Tests; Sentinel Lymph Node; Technetium; Uterine Cervical Neoplasms
PubMed: 33973745
DOI: 10.1002/cnr2.1401 -
Journal of Nuclear Medicine : Official... Oct 1985Technetium-99m galactosyl-neoglycoalbumin ([Tc] NGA), a labeled analog ligand to the hepatocyte-specific receptor, hepatic binding protein (HBP), was prepared and tested...
Technetium-99m galactosyl-neoglycoalbumin ([Tc] NGA), a labeled analog ligand to the hepatocyte-specific receptor, hepatic binding protein (HBP), was prepared and tested for labeling yield, stability, biodistribution, toxicity, and dosimetry. The ligand was synthesized by the covalent coupling of a carbohydrate bifunctional reagent, 2-imino-2-ethyloxymethyl-1-thiogalactose, to human serum albumin. Testing in mice and rabbits revealed the product to be nontoxic and apyrogenic. Technetium labeling yields in excess of 95%, by the electrolytic method, did not alter the molecular weight profile of the neoglycoalbumin. The NGA-bound activity remained stable for at least 4 hr. Biodistribution studies in rabbits demonstrated the liver as the single focus of tracer uptake. Dosimetry was based on kinetic studies in three baboons. Absorbed doses to liver, small intestine, urinary bladder wall, and uterus were 0.089, 0.28, 0.56, and 0.88 rad/mCi, respectively. Total body, lens of the eye, red marrow, ovaries, and testes were less than 0.06 rad/mCi. High liver specificity imparted by receptor binding combined with high labeling yield, stability, acceptable dosimetry, and safety provide [Tc]NGA with the attributes required for routine clinical assessment of hepatocyte function.
Topics: Albumins; Animals; Asialoglycoprotein Receptor; Carrier Proteins; Drug Evaluation, Preclinical; Energy Transfer; Female; Isotope Labeling; Kinetics; Male; Mice; Mice, Inbred BALB C; Organotechnetium Compounds; Papio; Quality Control; Rabbits; Radiation Dosage; Technetium; Tissue Distribution
PubMed: 4045560
DOI: No ID Found -
Journal of Nuclear Medicine Technology Jun 2010The accumulation of technetium by plants has been widely studied and reported in the literature from the perspective of the incorporation of environmental (99)Tc into...
The accumulation of technetium by plants has been widely studied and reported in the literature from the perspective of the incorporation of environmental (99)Tc into the food chain. Pertechnetate (TcO(4)(-)) is the most stable surface chemical form of technetium and is known to be extracted by plant roots, transported by the xylem, and reduced in the leaves; however, the mechanism of action is not entirely clear. Measuring the distribution of technetium in plants has been challenging, many questions remaining unanswered. To date, tracer studies for plant physiology (radionuclide and color dye) have relied on destructive sampling, prohibiting repeat-design experimentation. This article explores the technical issues relating to the application of scintigraphic imaging to plant physiology. The benefits and limitations of methods for introducing radiotracers to plants are outlined. Strategies for the successful labeling of various plant organs with (99m)Tc and several unanticipated artifacts are described. The relevance of these labeling experiments to the study of plant vascular transport is explained, and strategies for optimizing the scintigraphic imaging of plants are outlined. Assessing plant physiology is an emerging frontier, especially given the growing importance of water management and the increased competing demand for crops as biofuels.
Topics: Biological Transport; Image Processing, Computer-Assisted; Nuclear Medicine; Plant Physiological Phenomena; Plants; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium; Xylem
PubMed: 20484181
DOI: 10.2967/jnmt.109.071886 -
Chemistry (Weinheim An Der Bergstrasse,... Jan 2022Bis-arene sandwich complexes are generally prepared by the Fischer-Hafner reaction, which conditions are incompatible with most O- and N- functional groups. We report a...
Bis-arene sandwich complexes are generally prepared by the Fischer-Hafner reaction, which conditions are incompatible with most O- and N- functional groups. We report a new way for the synthesis of sandwich type complexes [Re(η -arene) ] and [Re(η -arene)(η -benzene)] from [Re(η -napht) ] and [Re(η -napht)(η -benzene)] , with functionalized arenes and pharmaceuticals. N-methylpyrrolidine (NMP) facilitates the substitution of naphthalene with the incoming arene. A series of fully characterized rhenium sandwich complexes with simple arenes, such as aniline, as well as with active compounds like lidocaine and melatonin are presented. With these rhenium compounds in hand, the radioactive sandwich complexes [ Tc(η -pharm) ] (pharm=pharmaceutical) can be unambiguously confirmed. The direct labelling of pharmaceuticals with Tc through η -coordination to phenyl rings and the confirmation of the structures with the rhenium homologues opens a path into molecular theranostics.
Topics: Naphthalenes; Pharmaceutical Preparations; Rhenium; Technetium
PubMed: 34817903
DOI: 10.1002/chem.202103566 -
Proceedings of the Japan Academy.... 2021Interest has been growing in the development of medical radioisotopes used for noninvasive nuclear medicine imaging of disease and cancer therapy. Especially the...
Interest has been growing in the development of medical radioisotopes used for noninvasive nuclear medicine imaging of disease and cancer therapy. Especially the development of an alternative production scheme of Mo, the mother radioisotope of Tc used for imaging, is required, because the current supply chain of the reactor product Mo is fragile worldwide. We have proposed a new production scheme of Mo as well as therapeutic radioisotopes, such as Cu and Cu, using accelerator neutrons provided by the C(d,n) reaction. Based on this scheme we have obtained high-quality Tc, Cu, and Cu suitable for clinical use by developing both production and separation methods of the radioisotopes. We proposed a new facility to constantly and reliably produce a wide variety of high-quality, carrier-free radioisotopes, including Mo, with accelerator neutrons. We report on the development of the proposed scheme and future prospects of the facility toward the domestic production of medical radioisotopes.
Topics: Molybdenum; Neutrons; Radioisotopes; Radiopharmaceuticals; Technetium
PubMed: 34121042
DOI: 10.2183/pjab.97.017 -
European Journal of Pharmaceutics and... Aug 2022Negatively charged microspheres (NCMs) are postulated as a new form of treatment for chronic wounds. Despite the efficacy shown at clinical level, more studies are...
Preclinical safety of negatively charged microspheres (NCMs): Optimization of radiolabeling for in vivo and ex vivo biodistribution studies after topical administration on full-thickness wounds in a rat model.
Negatively charged microspheres (NCMs) are postulated as a new form of treatment for chronic wounds. Despite the efficacy shown at clinical level, more studies are required to demonstrate their safety and local effect. The objective of the work was to confirm the lack of NCM systemic absorption performing a biodistribution study of the NCMs in an open wound rat animal model. To this end, radiolabeling of NCMs with technetium-99 m was optimized and biodistribution studies were performed by in vivo SPEC/CT imaging and ex vivo counting during 24 h after topical administration. The studies were performed on animals treated with a single or repeated dose to study the effect of macrophages during a prolonged treatment. NCM radiolabeling was achieved in a simple, efficient and stable manner with high yield. SPECT/CT images showed that almost all NCMs (about 85 %) remained on the wound for 24 h either after single or multiple administrations. Ex vivo biodistribution studies confirmed that there was no accumulation of NCMs in any organ or tissue except in the wound area, suggesting a lack of absorption. In conclusion, NCMs can be considered safe as local wound treatment since they remain at the administration area.
Topics: Administration, Topical; Animals; Microspheres; Rats; Technetium; Tissue Distribution
PubMed: 35697288
DOI: 10.1016/j.ejpb.2022.06.001 -
European Review For Medical and... Dec 2020The aim of this study was to propose a quantitative analysis method using technetium (Tc)-99m-labeled red blood cell RBC imaging to allow calculation of the amount and...
OBJECTIVE
The aim of this study was to propose a quantitative analysis method using technetium (Tc)-99m-labeled red blood cell RBC imaging to allow calculation of the amount and the rate of gastrointestinal (GI) bleeding.
MATERIALS AND METHODS
Rabbit models of fixed-GI and continuous-GI bleeding were created using catheter infusion. The amount and rate of bleeding were calculated and compared with the infused amount and rate.
RESULTS
No significant differences in calculated or actual amounts or rates of GI bleeding were observed after 2, 4, and 6 hours of catheter infusion of Tc-99m-RBCs.
CONCLUSIONS
The proposed quantitative analysis method using Tc-99m-RBCs GI scintigraphy can accurately calculate the actual amount and rate of GI bleeding.
Topics: Animals; Erythrocytes; Gastrointestinal Hemorrhage; Models, Animal; Rabbits; Radiopharmaceuticals; Technetium
PubMed: 33378028
DOI: 10.26355/eurrev_202012_24179 -
Environmental Science & Technology Nov 2015Technetium, uranium, and neptunium are contaminants that cause concern at nuclear facilities due to their long half-life, environmental mobility, and radiotoxicity. Here...
Technetium, uranium, and neptunium are contaminants that cause concern at nuclear facilities due to their long half-life, environmental mobility, and radiotoxicity. Here we investigate the impact of microbial reduction of Fe(III) in biotite and chlorite and the role that this has in enhancing mineral reactivity toward soluble TcO4(-), UO2(2+), and NpO2(+). When reacted with unaltered biotite and chlorite, significant sorption of U(VI) occurred in low carbonate (0.2 mM) buffer, while U(VI), Tc(VII), and Np(V) showed low reactivity in high carbonate (30 mM) buffer. On reaction with the microbially reduced minerals, all radionuclides were removed from solution with U(VI) reactivity influenced by carbonate. Analysis by X-ray absorption spectroscopy (XAS) confirmed reductive precipitation to poorly soluble U(IV) in low carbonate conditions and both Tc(VII) and Np(V) in high carbonate buffer were also fully reduced to poorly soluble Tc(IV) and Np(IV) phases. U(VI) reduction was inhibited under high carbonate conditions. Furthermore, EXAFS analysis suggested that in the reaction products, Tc(IV) was associated with Fe, Np(IV) formed nanoparticulate NpO2, and U(IV) formed nanoparticulate UO2 in chlorite and was associated with silica in biotite. Overall, microbial reduction of the Fe(III) associated with biotite and chlorite primed the minerals for reductive scavenging of radionuclides: this has clear implications for the fate of radionuclides in the environment.
Topics: Aluminum Silicates; Bacteria; Chlorides; Ferrous Compounds; Minerals; Neptunium; Oxidation-Reduction; Solutions; Technetium; Uranium; X-Ray Absorption Spectroscopy
PubMed: 26488884
DOI: 10.1021/acs.est.5b03463