Search Results
Abstract
The authors report here a new approach for making99mTc generators based on neutron irradiation of metallic molybdates and direct elution eliminating intermediate chemical processing steps. This approach tested using zirconium molybdate was found to yield99mTc with good yield and purity. This seems to be the simplest way of making column type99mTc generator even using low flux reactors and merits further detailed evaluation.
Abstract
A nomogram is presented to estimate the radiooctivity of99mTc in99Mo−99mTc generators, based on equations of radioactive equilibrium. Since the parent element decays through two isomeric states of the daughter, the ratio of the total mass of technetium per millicurie of99mTc is a function of the time elapsed between two consecutive elutions. Values of the amount of99mTc expressed as a mole fraction or in moles or grams of total technetium per millicurie of99mTcm are also presented.
Abstract
The confirmation that N-substituted imidodiacetic acids, as small and simple ligand systems containing amines and carboxylic acids, could be coordinated to the tricarbonyl core and form inert complexes with [99mTc (CO)3(H2O)3]+, is demonstrated. The HPLC quality control results of 99mTc-carbonyl tagged IDA molecules, performed by gradient HPLC, have shown that HIDA, EHIDA and p-butyl-IDA form complexes with [99mTc(CO)3(H2O)3]+, with a labeling yield of ~90% for each of 99mTc(CO)3 IDA derivatives. However, the changes in the structure of labeled compounds, e.g., EHIDA, influence the changes in the biological behavior. In comparison with 99mTc-EHIDA, the biliary excretion of 99mTc(CO)3 EHIDA was lower, but the urinary excretion higher.
Abstract
A new purity control method was developed in order to assure the radiochemical purity of thiamine pyrophosphate-Sn-99mTc. The method described consists in ascending cromatography using Whatman No 1 for support and 5% sodium citrate as solvent. It is capable of detecting free99mTcO 4 – and colloid formation, the most frequent impurities found in99mTc radiopharmaceuticals.
Abstract
The Radiopharmaceutical Group have undertaken a program to study and develop methods for production and quality control of different kinds of99mTc-kits. Here we present some results and properties for pyrophosphate, gluconate, phytate, DTPA, HEDPA and MDP kits. Work is under way to develop others' radiopharmaceuticals and99mTc-kits.
Abstract
Some parameters influencing the efficiency of labelling of bleomycin with99mTc using tin electrodes for electrolytic production of tin(II) ions were investigated. Different analytical techniques for quality control of99mTc-bleomycin were applied. From the results obtained, it has been concluded that gel filtration on Sephadex G-25 can give applicable information about the quality of this radiopharmaceutical.
Abstract
The aim of this research is to use acetylacetonate as a 99mTc chelating agent label with porphyrin and evaluate its radiochemical and biological characteristics. Stannous chloride was used as a reductant to determine the chemical and biological characterization of 99mTc-complexes from labeling porphine{4′,4′′,4′′′-(2lH,23H-Porphine-5,10,15,20-terayl)tetrakis-(benzoic acid), TPPB} with 99mTc–pertechnetate. Instant thin layer chromatography (ITLC), size exclusion chromatography (SEC), paper electrophoresis, and UV/Vis spectrophotometry were used to evaluate chemical characterization. Finally, biodistribution and liver function tests were applied to evaluate biological characteristics. The results of this study show that the labeling efficiency of 99mTc(acac)–TPPB was nearly 100% when using acetylacetone (acac) as a conjugator. Three major 99mTc(acac)–TPPB complexes were separated by SEC, and all of them were hydrophilic. The UV-Vis spectra of 99mTc(acac)–TPPB complexes closely resembled those of the TPPB, but the wave lengths of their peaks changed 430, 521, 556, 591 and 647 nm after complexation. The biodistribution study selected the liver as the target organ. The 99mTc(acac)–TPPB complex may cause short-term liver injury. However, this injury can be repaired, and the reagent is quickly metabolized. Hence, the toxicity of the 99mTc(acac)–TPPB complex is within an acceptable range, and making it a promising liver imaging agent.
Abstract
The aim of this study is to prepare radiolabeled guanine with 99mTc(CO)3 + core. For this purpose, guanine has been radiolabeled with 99mTc(CO)3 + core. Quality control study of radiolabeled guanine molecule with 99mTc(CO)3 + core was performed by thin layer radio chromatography (TLRC) and high performance liquid radio chromatography (HPLRC). The results showed that the radiolabeling yield was quite high (94 ± 3%). Beside that 99mTc(CO)3–Gua complex has showed good in vitro stability during the 24 h period. Radiopharmaceutical potential of this complex was evaluated in Wistar Albino Rats. It was concluded that 99mTc(CO)3–Gua could be used as a nucleotide radiopharmaceutical for in vivo applications.
Abstract
99mTc-labeled transferrin was prepared by reduction of99mTcO 4 − ; with stannous DTPA or stannous citrate followed by equilibration of the technetium chelate with human transferrin. The rate of transfer of99mTc to transferrin in the presence of 0.015M citrate buffer was dependent on pH in the order pH 2.1> pH 7.2> pH 4.1> pH 5.9. The incorporation rate was inversely proportional to the concentration of DTPA and citrate buffer. The replacement of citrate buffer by acetate buffer or oxalate buffer reduced drastically the formation of99mTc-labeled transferrin at pH 4.1. The formation of99mTc-labeled transferrin prepared from the reduction of99mTcO 4 − with stannous citrate was faster than that from the reduction with stannous DTPA in the presence of 0.015M citrate buffer and pH 2.5. Equilibration of transferrin with99mTc-labeled pyrophosphate did not produce99mTc-labeled transferrin at pH 4.5. The ligand exchange labeling of99mTc to transferrin in 0.015M citrate did not cause appreciable denaturation of the protein at all pH values. This method also enabled labeling of the protein in a low concentration (2.6·10−4 M) via tin reduction. Sequential external imaging of the99mTc-labeled transferrin in Sprague-Dawley rats bearing Walker-256 carcinosarcoma showed optimal tumor localization occurred at 3 hr after injection. In spite of this,99mTc-labeled transferrin does not appear to be a suitable imaging agent because of the low tumor to blood ratio of99mTc (0.50±0.17) at 3 hr post injection. This is similar to that of6 7Ga-citrate (0.43±0.15%).
Abstract
The aim of the current study was to design a nucleotide-based radiopharmaceutical which could be labeled with 99mTc and to investigate its radiopharmaceutical efficiency and stability. GHA (glucoheptonate) was used as bifunctional chelate. GHA was labeled with 99mTc by SnCl2 reduction method first, and then G (guanine) was conjugated with 99mTc-GHA at 90 °C. In order to determine its radiopharmaceutical stability, thin layer radio chromatography (TLRC) and electrophoresis were employed. In addition, the results were confirmed using high performance liquid radio chromatography (HPLRC). Scintigraphic imaging was performed on rats with mammary tumors, while tissue distribution was determined on Albino Wistar rats. Labeling yield was found to be over 95% and the labeled complex maintained its stability during the study period. The lipophilicity of the 99mTc-GHG was measured and the partition coefficient (logP) of the labeled compound calculated. The results demonstrated that the uptake of 99mTc-GHG (99mTc-glucoheptonate-guanine) reached its maximum at 3 hours p.i. in stomach and intestines. Main way of excretion was renal. Hepatobiliary excretion was also observed. In conclusion, 99mTc-GHG may be useful as a nucleotide-based radiopharmaceutical for in vivo applications.
