Synthesis and biodistribution of 99m Tc-PyDA as a potential marker for tumor hypoxia imaging

The ^99m Tc-pyrimidine-4,5-diamine (^99m Tc-PyDA) complex was prepared. The yield under the optimum conditions (5 mg of PyDA, pH 8, 25 μg of SnCl₂·2H₂O) was 96 ± 3%. The complex is stable in vitro for 24 h. The complex was tested on mice as potential marker for tumor hypoxia imaging. The complex showed high tumor hypoxia uptake with the target/nontarget (T/NT) ratio as high as ～3.     

Radiosynthesis of 99m Tc-labeled novobiocin dithiocarbamate complex as a potential Staphylococcus aureus infection radiotracer

The ^99m Tc complex with dithiocarbamate derivative of novobiocin, ^99m Tc(CO)₃-NBND, was prepared using the [^99m Tc(CO)₃(H₂O)₃]⁺ precursor. The complex was examined to evaluate its radiochemical permanence in saline and serum, in vitro bacterial uptake, and biodistribution in male Wistar rats (MWR). The ^99m Tc(CO)₃-NBND complex showed more than 90% radiochemical stability in saline for up to 4 h. The complex gave maximum stability of 99.10 ± 0.24% in saline after 30 min of reconstitution. In serum, 12.40% side products are accumulated within 16 h. The ^99m Tc(CO)₃-NBND complex showed 76.80 ± 0.90% in vitro binding with Staphylococcus aureus (S. aureus). In infected MWR muscles, ^99m Tc(CO)₃-NBND uptake was approximately 6 times higher than in inflamed and normal muscles. High stability of ^99m Tc(CO)₃-NBND in saline and serum, in vitro binding with live S. aureus, and specific higher uptake in the infected (live S. aureus) muscles make it a potential infection radiotracer.     

Synthesis of 99m Tc-L-carnitine as a model for tumor imaging

An L-carnitine derivative labeled with ^99m Tc was prepared. It is effective in tumor imaging. The labeling was done using SnCl₂ as a reducing agent. The optimum conditions required to label 25 ??g of L-carnitine were as follows: 100 ??g of SnCl₂, 30 min reaction time, room temperature, pH 7 (0.5 M phosphate buffer). The radiochemical purity of the labeled compound was determined by paper chromatography. The yield was about 93%. About 2.5 × 10⁶ Ehrlich ascites carcinoma (EAC) cells were injected intraperitoneally to produce ascites and intramuscularly in the right thigh to produce solid tumor in female mice. Biodistribution studies were carried out by injecting a solution of ^99m Tc-L-carnitine into normal and tumor-bearing mice. The uptake in ascites and in solid tumor was over 5% of the injected dose per gram tissue at 4 h post injection. These data revealed localization of the tracer in the tumor tissues with high percentage sufficient to use ^99m Tc-L-carnitine as a promising tool for diagnosis of tumor.     

Synthesis of 99m Tc-erythromycin complex as a model for infection sites imaging

Labeling of erythromycin with ^99m Tc using SnCl₂·2H₂O as a reducing agent was investigated. Dependence of the yield of ^99m Tc-erythromycin complex on the concentrations of erythromycin and reducing agent, on pH, and on the reaction time was studied. 97% labeling yield of ^99m Tc-erythromycin complex was achieved by performing the reaction with 1.5 mg of erythromycin and 15 μg of SnCl₂·2H₂O at pH 4 for 15 min. ^99m Tc-erythromycin complex was stable for 6 h. Biodistribution studies in Albino mice bearing septic and aseptic inflammation models showed that ^99m Tc-erythromycin does not allow differentiation between septic (Staphylococcus aureus) and aseptic inflammation. The maximum accumulation of ^99m Tc-erythromycin at the infection site was observed in 30 min after administration and was followed by gradual decline. The abscess-tomuscle ratio for ^99m Tc-erythromycin was 5 ± 0.6, whereas that for the commercially available ^99m Tc ciprofloxacin was 3.8 ± 0.8.     

Synthesis and evaluation of 99m Tc-NIDA and 99m Tc-DMIDA complexes for hepatobiliary imaging

1-Naphthylcarbamoylmethyliminodiacetic acid (NIDA) and diphenylmethylcarbamoylmethyliminodiacetic acid (DMIDA) were synthesized, characterized, and labeled with ^99m Tc using SnCl₂ as reducing agent. The parameters affecting the yield of ^99m Tc-NIDA and ^99m Tc-DMIDA were studied in detail. The optimum conditions ensuring high yield of ^99m Tc-NIDA (94.2 ± 2%) and ^99m Tc-DMIDA (93.1 ± 2%) are as follows: 30 mg of NIDA or DMIDA, 0.3 mg of SnCl₂·H₂O, pH 6, 15 min. The biodistribution in mice injected with ^99m Tc-NIDA and ^99m Tc-DMIDA showed high liver uptake at 10 min post injection, with fast biliary excretion. Accumulation of the activity in kidneys was negligible, especially after a long time post injection. Both ^99m Tc-NIDA and ^99m Tc-DMIDA can be applied as hepatobiliary imaging agents for the evaluation of the functional status of the hepatocytes and the patency of the biliary duct.     

Use of99m Tc as an energy standard for electron spectroscopy: promise and limitations

An electrostatic spectrometer was used to study the dependence of the position of theM ₅ line of conversion electrons from the 2.17-keV transition in⁹⁹Tc on the source thickness, in samples of different chemical compounds of Tc: metallic technetium, technetium dioxide, and pertechnate. Recommendations are given concerning the use of a source in the form of a film of metallic technetium (less than 10⁻⁷ g/cm² thick) on a platinum substrate for calibrating electron spectrometers in the energy range of a few kiloelectron volts. A procedure is described for preparing films of metallic technetium. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 66–68, August, 1997.     

Technetium-99m Labeling of Antineoplaston A10 and Its Bioevaluation as a Potential Tumor Imaging Agent

Radiochemistry - Antineoplastons (ANPs) are compounds that have antitumor activities. ANPA10 was labeled with technetium-99m using stannous chloride as a reducing agent with the labeling yield of...     

Radiochemical and biological characterization of 99m Tc-piracetam for brain imaging

Experiments on piracetam labeling with ^99m Tc were performed. The radiochemical yield of 97% was obtained under the optimum conditions: pH 6, SnCl₂·2H₂O as reducing agent, room temperature, 30 min. In vivo biodistribution studies showed that the initial brain uptake correlated fairly well with the brain binding affinity of the compound. The brain uptake of ^99m Tc-piracetam was as high as 6, 12.3, 5.3, and 3.3% per gram tissue at 5, 30, 60, and 120 min post injection, respectively. ^99m Tc-piracetam shows promise in radioreceptor assays of neuroleptic drug levels and, in the labeled form, for brain imaging.     

Labeling and biological evaluation of 99m Tc-azithromycin for infective inflammation diagnosis

Azithromycin, an antibiotic used to treat bacterial infections, was labeled with ^99m Tc. The maximum radiochemical yield of ^99m Tc-azithromycin, 97.5 ± 0.9%, was attained under the following conditions: addition of ^99m Tc to 2 mg of azithromycin in the presence of 50 μg of SnCl₂·2H₂O at pH 4, reaction time 30 min. ^99m Tc-azithromycin complex was stable for 6 h. Biological distribution of ^99m Tc-azithromycin was studied in mice infected with Staphylococcus aureus in the left thigh. The ratio of ^99mTc-azithromycin uptake in the bacterially infected and contralateral thighs, T/NT, for was found to be 6.20 ± 0.12 at 2 h after intravenous injection (higher than the ratio obtained with the commercially available ^99m Tc-ciprofloxacin), which was followed by gradual decline. The results obtained show that ^99m Tc-azithromycin can be used for infection imaging and allows differentiation between bacterial infection and sterile inflammation.     

Labeling of omeprazole with technetium-99m for diagnosis of stomach

Omeprazole, a proton pump inhibitor, was labeled with ^99m Tc to obtain ^99m Tc-omeprazole in ～96% yield in basic media. The optimum conditions were as follows: pH 9, 50 μg of SnCl₂·2H₂O, 30 min, and 3 mg of the substrate. ^99m Tc-omeprazole was stable for 6 h. Intravenous biodistribution of ^99m Tc-omeprazole showed that it concentrated in the stomach ulcer to reach about 22% of the total injected dose at 1 h post injection. This concentration of ^99m Tc-omeprazole in stomach ulcer may be sufficient for ulcer imaging.     

Optimization of labeling conditions and bioevalution of 99m Tc-Meloxicam for inflammation imaging

Labeling of Meloxicam with ^99m Tc was done by direct addition of pertechnetate in isotonic solution to Sn-Meloxicam solution. High labeling yield (98%) was attained in 30 min at room temperature. The effect of various factors on the labeling yield was studied. No less than 0.5 mg of Meloxicam should be used to prevent the formation of colloids in the reaction medium. 75 μg of stannous chloride dihydrate was found to be sufficient to reduce all pertechnetate without the detection of free pertechnetate or colloids in the reaction mixture. The labeling should be done in alkaline solutions (pH 9–11). The labeled compound was separated and purified by HPLC. The biological distribution in infected mice demonstrates the suitability of ^99m Tc-labeled Meloxicam for inflammation and tumor imaging.     

Development of an automated unit for extraction-chromatographic separation of the 99Mo/99m Tc generator couple

The design and automatic control scheme were developed for an extraction-chromatographic unit for producing ^99m Tc preparations. The unit is intended for operation under the conditions of medical radiological laboratories. Technical trials showed that the mean time of preparation of sodium [^99m Tc]pertechnetate radiopharmaceutical did not exceed 25 min.     

An intercomparison of a Cu nuclear susceptibility thermometer and an Sn99 mösbauer effect thermometer between 6 mK and 1 K

The cold-absorber Sn¹¹⁹ Mössbauer effect thermometer discussed by Parshin et al, has been compared with the steady-field Cu nuclear magnetic susceptibility thermometer. The Curie constant of the Cu thermometer was also determined from simultaneous measurements using a ballistic CMN thermometer. The sensors were installed in the mixing chamber of a dilution refrigerator capable of producing temperatures below 6 mK in the single cycle mode. The absorber never cooled below 7.8 mK due to heat leaks. Good consistency and reproducibility were established between 10 and 100 mK.     

Graphene transistor as a probe for streaming potential

We explore the dependence of electrical transport in a graphene field effect transistor (GraFET) on the flow of water/sodium chloride electrolyte within the immediate vicinity of that transistor. We find large and reproducible shifts in the charge neutrality point of GraFETs that are dependent on the liquid velocity and the ion concentration. We show that these shifts are consistent with the variation of the local electrochemical potential of the liquid next to graphene that are caused by the fluid flow (streaming potential). Furthermore, we utilize the sensitivity of electrical transport in GraFETs to the parameters of the fluid flow to demonstrate graphene-based mass flow and ionic concentration sensing. We successfully detect a flow as small as ～70 nL/min and detect a change in the ionic concentration as small as ～40 nM.     

Labeling of tannic acid with technetium-99m for diagnosis of stomach ulcer

A procedure was developed for labeling tannic acid with ^99m Tc. The following conditions are required to achieve 95.5% yield of ^99m Tc-tannic acid: 150 μg of SnCl₂·2H₂O, 50 μg of the substrate, 30 min, pH 7. ^99m Tc-tannic was stable for 6 h. Experiments on biodistribution of orally administered ^99m Tc-tannic acid showed that it is concentrated in the stomach ulcer (50% of the total administrated dose at 1 h post administration). This concentration of ^99m Tc-tannic acid in stomach ulcer may be sufficient for ulcer radioimaging.     

A procedure for sorbent pretreatment for the production of high-activity 99Mo/99m Tc generators based on enriched 98Mo

The effect of the acid treatment on the adsorption capacity of aluminum oxides for Mo was examined. The areas of the initial (??_o) and limiting (??_lim) saturation of neutral and acidic aluminum oxides with hydrochloric acid were determined. The Mo adsorption maximum is attained at the limiting saturation, with the subsequent exponential decrease on approaching the point in which the interaction of the oxide with the acid starts to decelerate, after which the adsorption drastically decreases. In the area close to ??_o, the Mo breakthrough to the eluate is observed at any adsorbed amount of Mo. The results obtained allow prediction of the acid amount required for the adsorption of the preset amount of Mo.     

Comparison between a finite element and a composite method for a three-dimensional potential problem

This paper is concerned with the solution of the three-dimensional potential problem for electromagnetic river gauging. It extends previous ideas of joining finite elements in an interior region to one infinite external element treated by the boundary integral method^1,2 to this case where there are two external infinite elements representing the river and the ground. The boundary continuity conditions on the infinite river–ground interface, as well as the internal–external interfaces, are dealt with by introducing a variational principle with relaxed continuity requirement³.     

Preparation and Biodistribution of 99mTc-Trazodone as a Brain Imaging Probe

Radiochemistry - Trazodone was labeled with 99mTc by indirect method. More than 97% radiochemical yield was reached under the following optimized conditions: 100 µg of Trazodone, pH 7, 10 mg...     

99m Tc-labeled teicoplanin and its biological evaluation in experimental animals for detection of bacterial infection

Labeling of teicoplanin with ^99m Tc using SnCl₂·2H₂O as reducing agent was performed. The dependence of the ^99m Tc-teicoplanin yield on the concentrations of teicoplanin and reducing agent, pH of the reaction mixture, reaction time, and reaction temperature was studied. Under optimum conditions (2 mg of teicoplanin, 5 μg of SnCl₂·2H₂O, pH 9, 30 min, 25°C), the labeling yield of ^99m Tc-teicoplanin of 87.7 ± 1.3% was achieved. ^99m Tc-teicoplanin is stable for 4 h after labeling; then its relative content decreased gradually to reach 81.7 ± 1.1% in 8 h. Biodistribution studies in mice with infection induced in the left thigh by Staphylococcus aureus were carried out. The bacterial infected thigh/contralateral thigh uptake ratio (T/NT) was evaluated. The time for the maximum accumulation of ^99mTc-teicoplanin in the infection site was 2 h after administration of the labeled compound. The abscess-to-muscle ratio for ^99m Tc-teicoplanin was 4.33 ± 0.3, while that for commercially available ^99m Tc-ciprofloxacin was 3.8 ± 0.5 under similar conditions. Thus, ^99m Tc-teicoplanin can be used for infection imaging.     

Synthesis and properties of 99Tc(I) and 99m Tc(I) hexacarbonyl in aqueous solutions

A procedure was developed for preparing Tc(CO)₆ClO₄ by carbonylation of a solution of technetium(I) tricarbonyltriaqua complex in 2 M HClO₄ in a pressure vessel at 100–170°C and CO pressure of 150 atm. The hexacarbonyltechnetium cation in solution was characterized by IR and ⁹⁹Tc NMR spectroscopy, and also by high-performance liquid chromatography (HPLC). The effect of particular acid and of synthesis conditions on the yield of the hexacarbonyltechnetium cation was examined, and the stability of this cation in aqueous solutions was evaluated. Conditions were found for preparing an aqueous solution containing ^99m Tc(CO) ₆ ⁺ .