Biomedical subjects
Publications and source records attributed to S M Shaw.
The dissolution profiles for [131I]sodium iodide therapeutic capsules from three commercial vendors were studied. The 131I release rate in water was rapid for the capsules with 100% release attained within 35 min. There was no significant difference in dissolution profiles for the capsules from the three vendors.
The biodistribution of [75Se]BISTAES was studied in guinea pigs. A higher concentration of radioactivity was observed in articular cartilage than in other tissues or organs. A minimal amount of radioactivity was found in the blood, muscle and bone. The compound was excreted rapidly in urine. The target to background ratios were encouraging. [75Se]BISTAES has potential as an articular cartilage imaging agent and further studies in osteoarthritic animals are merited.
This study looks at techniques for promoting fitness participation among adolescent girls, in particular those which emphasize the "slim ideal." Various promotional posters were designed which systematically used different models (slim, average, and overweight) and different messages (slimness, activity, and health). The relative effectiveness of these posters was tested using a probability sample of 627 female high school students. The slim model was found to be the most effective poster, while slimness was the least effective of the messages. Demographic and self- and body-image factors had relatively little effect on the ratings of the posters. Focus group interviews conducted with the student sample indicated that they were concerned about their body weight, and that they associated slimness with fitness. However, the slimness message was not thought to encourage participation in fitness because overt emphasis on body image may lead to self-consciousness and fear of social rejection. The idea that participation would lead to a slim physique was also thought to be unrealistic. The students were more critical of the slimness message than of the slim model in the posters. Overall, the data indicate that promoting fitness through messages relating fitness to slimness is not an effective approach with adolescent girls. The use of very slim models in promotional material may be effective, but this approach may not be desirable because it reinforces the dominant cultural stereotype of the "ideal" slim female form.
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The biodistributions of six chromatographically pure 99mTc-HEDP complexes have been determined in soft tissues, normal bone and osteogenic lesions (induced with a Walker 256 tumor) in Fisher 344 rats. The physical properties of each 99mTc-HEDP complex including anionic charge, partial molar volume, molecular weight and spectral characteristics are known; thus allowing structure-activity relationships to be drawn. The results indicate that the smallest, low charged, mononuclear 99mTc-HEDP complexes have the greatest uptake in bone lesions, and the highest lesion to muscle and lesion to normal bone ratios.
A mammalian model has been developed for the in vivo evaluation of bone imaging agents. The model is based upon the quantification of a discrete, initial secondary periosteal osteogenesis induced in cortical bone immediately adjacent to an intramuscularly implanted Walker 256 tumor in Fisher 344 rats. Evaluation of the model consists of a histopathological examination of the periosteal bone formation, biodistribution studies on 99mTc-MDP and 99mTc-HMDP commercial kit preparations, and biodistribution studies on two 99mTc-HEDP component fractions isolated after anion exchange chromatographic separations from an investigative "carrier added" preparation. Reversed phase HPLC separations of the 99mTc-MDP and 99mTc-HMDP commercial kit preparations illustrate distinct differences in chemical composition between the two bone agents.
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The deterioration of stannous ion (Sn++) in inhouse-prepared and commercial radiopharmaceutical kits was studied. Sn++ content of three types of nonlyophilized, deoxygenated, aqueous inhouse-prepared kits [diethylenetriamine pentaacetic acid (DTPA), pyrophosphate and glucoheptonate] and of three commercially prepared kits (two lyophilized pyrophosphate kits and one diphosphonate in sealed glass ampul kit) was measured by differential pulse polarography. Inhouse-prepared kits were assayed initially and after storage for 6, 12, 24 and 48 days at 24, 5 and -18 C. Commercial kits were assayed initially and after storage for 12, 24 and 48 days at 5 and 24 C. Of the inhouse-prepared kits, Sn++ stability when stored for 48 days at 5 and 24 C. Freezer storage should be used, when possible, to insure maximum stability of Sn++ in inhouse-prepared, nonlyophilized ratiopharmaceutical kits. The commercial procedures of lyophilization and of sealing the reagent in a sealed glass ampul prolong Sn++ stability.
Pregnant rats received a single administration of 0.5, 1.0, or 2.0 mg/kg of cadmium on day 18 or 20 or gestation. Maternal animals were killed on day 21 and samples of the caudate nucleus from fetal brains were examined using the transmission electron microscope. A 2.0 mg/kg dose of cadmium administered to maternal rats on day 20 of gestation caused the formation of vacuoles in the endothelial cells of capillaries in the fetal brain. Significant endothelial cell vacuolization was not observed in the brain of fetuses from other treatment groups. The vacuoles occurred singly, were spherical in shape, were located adjacent to the intercellular junctions and caused focal distortion of the endothelial cell. Vacuoles were the only ultrastructural alteration observed in the caudate nucleus of fetal brains.
Liposome formulations were studied to achieve an efficient entrapment procedure for the production of liposomes of 99mTc-pentetic acid. The entrapment efficiency was studied by separation of the product using column chromatography. The particle-size range of the prepared liposomes was evaluated using electron microscopy. Entrapment techniques and separation procedures led to a liposome preparation with particles in the colloidal size range (0.001-0.5 micron). Dramatic differences in the organ distribution of the liposome preparation in mice were produced when different particle-size ranges were injected. Liposomes eluted in the first fraction after the void volume led to a maximum uptake by the liver and spleen 10 min after intravenous injection. Liposomes from pooled fractions provided less than half of the activity in the liver, as did the narrow size range liposome preparation.