Depew M. Chauncey

The effect of parathyroid hormone on technetium-99m pyrophosphate distribution in rats

Sprague-Dawley rats were treated with varying quantities of parathyroid hormone for 1–3 days, then sacrificed at periods ranging from 1–6h after administration of 99mTc-pyrophosphate. Very little increase in bone accumulation of tracer occurred with this treatment. A small, but obvious decrease occurred in the blood levels of 99mTc-pyrophosphate and a smaller and less consistent decrease was affected in the muscle levels of the radiopharmaceutical. The overall result was an improvement in the bone/blood and bone/muscle ratios. It is suggested that the basis of the “supernormal” bone scan of hyperparathyroidism is achieved by this mechanism and that the increased bone uptake of other ions in response to parathyroid hormone is not shared by 99mTc-pyrophosphate.

The effect of certain variables on the tumor and tissue distribution of tracers. Part 1; Carrier.

Buffalo rats bearing thigh-implanted strain-7777 Morris hepatomas were used as a model for studying the effect of carrier material on the body distribution, tumor uptake, excretion, and tumor-to-background ratios of 67Ga and 54Mn. An effort was also made to observe the changes in 67Ga and 54Mn concentrations induced by carrier in viable tumor and skeletal muscle, relative to their interstitial fluid space. This value is referred to as the Tissue Distribution Index. Carrier manipulation resulted in striking changes in the distribution of the two ions from the carrier-free state. The data also indicated a difference in the pharmacodynamics of 67Ga and 54Mn in malignant and healthy tissues which could be of importance to nuclear medicine and oncology.

The distribution of cadmium-115m chloride, cobalt-57 bleomycin, iodine-125 human serum albumin, selenium-75 selenite and selenomethionine-75 in a rat hepatoma model: a comparison with gallium-67 citrate.

The distribution of cadmium-115m chloride, cobalt-57 bleomycin, selenium-75 selenite, selenium-75 selenomethionine and iodine-125 human serum albumin was investigated in rats bearing thigh implanted Morris 7777 hepatomas. Viable and nonviable tumor tissue were collected in order to determine the relative affinities of these radiopharmaceuticals for these tissues. Groups of animals were sacrificed at 4, 24, 48, 72 and 96 h following injection. Viable tumor-to-blood and muscle ratios for cadmium-115m chloride and cobalt-57 bleomycin were higher than those for gallium-67 bitrate at 4 h post-injection. The unusually high cobalt-57 bleomycin ratios for both viable and nonviable tumor were the result of very low muscle and blood values rather than high tumor uptake. Tumor-to-background ratios for iodine-125 human serum albumin, selenium-75 selenomethionine and selenium-75 selenite were inferior to those derived for cobalt-57 bleomycin or gallium-67 citrate. None of the agents included in this study compared well with gallium-67 citrate as a tumor localizing agent with the possible exception of cadmium-115m chloride and coblat-57 bleomycin at early time periods. As in most other radiopharmaceuticals studied in this model, a reversal occurred in the viable-to-nonviable tumor ratios as the time after injection increased.

Preparation and stability of 131I-tetracycline

Abstract A method for the iodination of tetracycline is presented which yields >85% labeling efficiency. The product is stable for a minimum of 72 hr and appears to retain tetracycline-like properties when studied in vivo . The critical factors in the synthesis are reaction temperature, acidity, and drying temperature. The data suggest that 131 I-TET can be studied as a tumor scanning agent without fear of product artifact.

Distributions of 137Cs, 201Tl, 203Hg, 203Pb and 57Co in a rat hepatoma model. Comparison with 67Ga.

The distribution of carrier-free 203Pb-acetate, 203HgCl2, 57 CoCl2, 137CsCl and 201TlCl was investigated in rats bearing thigh-implanted Morris 7777 hepatomas. Viable and nonviable tumor tissue was collected in order to determine the relative affinities of the radiopharmaceuticals for these tissues. The animals were sacrificed at 4, 24, 48, 72 and 96 hrs following intravenous injection. Washout of the radioisotope from the viable tumor tissue was rapid, the maximum concentration being reached on or before 4 hrs following injection. In contrast, residual activity within the nonviable tumor tissue decreased much more slowly and in some cases even increased with time. Viable tumor-to-muscle and nonviable tumor-to-muscle ratios for 203Pb, 203Hg and 57Co were comparable to the analogous ratios reported for 67Ga. However, none of these isotopes approached 67Ga as a potential tumor imaging agent because the large ratios were the result of low muscle uptake rather than high tumor uptake. Blood clearance of 67Ga was faster than any of the five cations, while viable and nonviable tumor affinity for 67Ga was greater than for any of the radiopharmaceuticals studied.