Evaluation of the in vitro effect of a Lantana camara extract on the labeling of blood constituents of rats with technetium-99m.

Blood constituents labeled with technetium-99m (99mTc) have been used in nuclear medicine procedures and drugs are capable to interfere on this labeling. Lantana camara (lantana) has medicinal properties and it has been used in folk medicine. The aim is to verify the effect of a lantana extract on the labeling of blood constituents with 99mTc. Blood of rats was incubated with extract, stannous chloride and 99mTc, as sodium pertechnetate. Plasma (P) and blood cells (BC) were isolated, also precipitated with trichloroacetic acid and soluble (SF) and insoluble fractions (IF) were separated. The % of radioactivity (%ATI) in these samples was calculated. Samples of labeled BC were washed and the %ATI maintained (%ATI-M) in the BC was determined. The results showed that lantana extract decreased significantly (p < 0.05) in the IF-P from 70.24 +/- 2.59 to 11.95 +/- 3.07. This effect was not observed in the BC and IF-BC. The BC-%ATI-M was significantly (p < 0.05) decreased in all concentrations tested when the BC was washed. This fact was not observed in the control. Substances present on the extract should have redoxi action decreasing the concentration of the stannous ion and this condition could justify the effect on the IF-P. The results about the BC-%ATI-M should indicate a possible effect on the transport of ions through the erythrocyte membrane.

Quality control validation for exogenous natural surfactant labeled with 99mTc.

OBJECTIVE: Exogenous natural surfactant (ENS) labeled with 99mTc shows an elevated lung specificity allowing the acquisition of high-quality images for ventilation scintigraphy. METHODS: The methods for 99mTc-ENS quality control (physical properties, pH determination, radiochemical studies, and biologic studies) were evaluated and validated. RESULTS: The physical properties of the nonradioactive precursor and of the radiopharmaceutical were analyzed as general descriptors of the product. The pH of the radiopharmaceutical was determined by using pH test papers, a method described and validated in the United States Pharmacopeia. Chromatographic studies performed using the acetone/Whatman-1 paper system were validated as a method to evaluate the radiochemical purity of the 99mTc-ENS. Biodistribution studies on rats after intratracheal administration were validated as a method to estimate the radiopharmaceutical biodistribution in humans. CONCLUSION: The proposed method for 99mTc-ENS quality control studies and stability studies was evaluated and validated following international standards.

Procedure for radiolabeling gizzerosine and basis for a radioimmunoassay.

A method for the labeling of gizzerosine (GZ), a biogenic amine found in fish meal, is described. The labeling procedure with (125)I using a water-soluble Bolton-Hunter reagent and a mild water-insoluble oxidant (Iodogen) reagent is rapid and reproducible. The (125)I-GZ hapten was demonstrated to be immunologically active in a radioimmunoassay developed with polyclonal antibodies to GZ absorbed with a histamine-Sepharose column. The curves were linear in the range of 0.0001 and 0.1 microgram/mL. Samples of fish meal previously extracted of histamine with methanol and submitted to acid hydrolysis were contaminated with known amounts of GZ and submitted to the assay. The fish meal samples contaminated with GZ show a dose-response effect similar to the standard curve, and apparently the other component present in the sample did not interfere with the binding of the antibodies to (125)I-GZ. These data indicate the suitability of the radioimmunoassay to determine specifically GZ in fish meal.

99mTc direct labeling of anti-CEA monoclonal antibodies: quality control and preclinical studies.

The anti-carcinoembryonic B2C114 monoclonal antibody was radiolabeled with 99mTc by a direct method and quality control tested in vitro by instant thin layer chromatography, gel column scanning and cellulose acetate electrophoresis and assessed in vivo for radioimmunodetection on a murine spontaneous mammary carcinoma. The optimal results of percent 99mTc bound to protein were obtained at a dithiothreitol:antibody molar ratio ranging from 800:1 to 1000:1 and at a methylene diphosphonate:stannous fluoride weight ratio of 4.3:1. Although cysteine removed up to 18% of the label during the first 4 h, the stability of the tracer appeared to be excellent in human serum at 37 degrees C and when challenged with DTPA. 99mTc-labeled B2C114 demonstrated good and specific in vivo tumor targeting.