Effect of mixed ligand complex therapy on the retention of 95Nb and 144Ce in mice.

We have examined in mice the effects of mixed ligand treatments with desferrioxamine B (DFOA), Na3Ca-diethylenetriamine pentaacetic acid (DTPA), and DL-penicillamine (PA) on the retention of a mixture of 95Nb and 144Ce. The results show that 95Nb + 144Ce could be mobilized effectively by simultaneous application of specific agents (i.e., DFOA, DTPA) with no decrease in their efficiencies.

Age-related efficiency of Ca-DTPA to reduce 141Ce retention in rats.

The study was aimed at evaluating the influence of age on the efficiency of chelation therapy for cerium in case of late administration. The efficacy of trisodium calcium diethylene-triaminepentaacetate (Ca-DTPA) administered as a first dose 48 and 72 h after 141Ce was investigated in 8-week-old and 2-week-old rats. The effect of treatment gradually decreased depending on the time period between radionuclide and chelating agent administration. Higher efficacy of chelation therapy in reducing the whole-body retention of 141Ce in older animals was constantly shown to be independent of the time of administration of chelating agent. The influence of age on the efficacy of chelation therapy was different for various organs and tissues; e.g., for liver and gut chelation therapy it was more effective in older animals, for kidneys it was equally effective in both age groups, while for bone it was more effective in the younger animals. The present results indicate that the effect of age in chelation therapy is influenced by the time of administration of the agent as well as by radionuclide distribution in organs and their availability for chelation.

153Gadolinium as a useful radiolanthanide for long-term labeling of tissues in Japanese quail.

153Gadolinium (153Gd), with gamma energies of 97 keV (30%) and 103 keV (20%), and a nuclear-life of 242 days and with no primary charged particles, was selected as the radiolanthanide for labeling proteins and tissues in Japanese quail. Ranges of dose-responses 18 hr after giving Gd (153Gd labeled) were: males, livers 24.4% for .00015 mumol/100 g to 63.8% for .15 mumol/100 g; laying females, livers 6.5% for .00015 mumol/100 g to 72.7% for 15 mumol/100 g and growing oocytes 83.2% for .00015 mumol/100 g to 6.4% for 15 mumol/100 g. Accumulation of .015 mumol/100 g doses of 153Gd in tissues common to both sexes were greater in males than in females at 1, 6, and 18 hr. The exception was the pancreas, where for all three sampling times the percentages for females were twice those for males. Comparison of 153Gd with 140lanthanum (140La) showed 18-hr levels of 27%/g liver in males and 1.6%/g liver and 11.8%/g growing oocyte in females for both nuclides. Double-labeling with 153Gd and 144cerium (144Ce) showed that a near-toxic dose of La (15 mumol/100 g) caused a marked decrease in labeling of growing oocytes (e.g., largest oocyte, La-treated females, Gd 14.6%, Ce 6.1%; controls Gd 42.2%, Ce 35.5%) and a marked increase in labeling of livers (La-treated, Gd 51.2%, Ce 43.3%; controls; Gd 7.62%, Ce 4.75%).

The behavior of 137Cs and other fallout radionuclides on a Michigan dairy farm.

The behavior of the fallout radionuclides 137Cs, 54Mn, 14Ce-Pr and 90Sr in the milk-food chain was studied at a commercial dairy farm near Tecumseh, Michigan during 1964 and 1965. The main purpose of the study was to develop mathematical models to describe the movement of radionuclides from air to milk. Three models are presented: the first predicts the total deposition on precipitation collectors given the air concentration and rainfall rate; the second predicts the concentration in forage from air concentration, rainfall rate, and the rates at which the forage grows and is consumed by the dairy herd; the third predicts the milk concentration from the concentration in each type of feed and the rate at which each feed type is consumed by the dairy herd. The first two models are applicable to all four radionuclides but the milk model is valid only for 137Cs. Milk concentrations for the other three radionuclides are treated individually. The model for deposition on precipitation collectors was developed independently and is shown to predict weekly deposition rates to within a factor of three (95% of the time). This uncertainty is reduced as the time span for the prediction is increased. Development of the other two models was based in part on data from the Tecumseh study; both still require independent verification. The forage model fits the weekly experimental data to within a factor of 2.2. The milk model fits the weekly measurements of 137Cs concentrations to within a factor of 1.5. The error of the latter 2 models also decreases as the time span for the prediction is increased.

Reduction of 85Sr, 137Cs, 131I and 141Ce retention in rats by simultaneous oral administration of calcium alginate, ferrihexacyanoferrate(II), KI and Zn-DTPA.

The effect of simultaneous oral administration of a mixture of calcium alginate, ferrihexacyanoferrate(II) and KI and of the chelating agent zinc diethylenetriaminepentaacetate (Zn-DTPA) on the retention of radioactive Sr, Cs, I and Ce was investigated in 7-week-old female rats. The respective antidotes were administered in food during the first three days of the experiment and the radionuclides were administered on the second day of the experiment. The radionuclide retention was determined in the whole body, carcass, gut, liver, kidneys and respective critical organs six days after oral administration of 85Sr, 137Cs, 131I and intraperitoneal administration of 141Ce and one day after oral administration of 141Ce. Simultaneous oral administration of the four therapeutic agents reduced the retention of radioactive Sr, Cs and I administered orally and Ce applied intraperitoneally. Zn-DTPA did not diminish efficacy of antidotes from the mixture nor did the mixture significantly alter the effect of Zn-DTPA. Simultaneous oral administration of calcium alginate, ferrihexacyanoferrate(II), KI and Zn-DTPA might present a convenient method for delayed therapy especially in cases of prolonged increased environmental exposure to several radionuclides.

Dietary treatment for decreasing 141Ce body burden in immature rats.

The purpose of this work was to evaluate the effect of prolonged (immediate or delayed) administration of dietary additives to suckling rats on the absorption and retention of radioactive cerium in the body. The experiment was performed on 6-day-old suckling rats. According to dietary treatment the animals were divided into three groups. Each group was artificially fed over 8 h for 6 or 12 days on one of the diets: the first group of animals was fed milk, the second group was given ingredients of rat diet and the third received milk during the first 2 days of the experiment and the ingredients of rat diet afterwards. At the end of the artificial feeding period the pups returned to their mothers and suckled overnight. On the 1st day of the experiment the food was labelled with 141Ce. Whole body radioactivity was determined in a double crystal scintillation counter every 48 h over a 12-day period. Half of the animals from each group were killed 6 days after 141Ce administration and the other half after 12 days. At these intervals retention was determined in the gut, liver, kidneys and femur. The early and delayed administration of rat diet ingredients--fish meal, sunflower meal, alfalfa, cane molasses and premix--greatly reduced whole body retention. The early treatment was more efficacious than the delayed one. The reduction was mostly due to decreased gut retention but organ retentions were also lower. The results obtained indicate that by prolonged (immediate or delayed) administration of some dietary means the retention of radioactive cerium in sucklings can be significantly decreased.

Reduction of 141Ce absorption in suckling rats.

The influence of diet or its ingredients on 141Ce absorption and retention was investigated in six-day-old rats. Animals were fed over 8h with cow's milk, rat diet or a mixture of rat diet ingredients (fish meal, sunflower meal, alfalfa, cane molasses and premix) labelled with 141Ce. Whole-body radioactivity was determined in a double crystal scintillation counter every 24 h over a six-day period. Gut, liver, kidney and femur retention and cerium distribution in the gut was determined at the end of the experiment. Compared to milk diet, administration of rat diet or ingredients caused respectively 3 and 7.5 times lower whole body retention. Carcass retention was reduced by rat diet or ingredients 2-3 times and intestinal retention 3 and 8 times respectively. Irrespective of the dietary treatment the main site of cerium intestinal retention was the ileum. Our present results indicate that some compounds of rat diet might be considered as a means of reducing cerium absorption and intestinal retention in the very young.

Effect of 60Co-Gamma whole body irradiation and treatment with radioprotector on the retention of 144Ce, in mice.

In animal experiments the effects of 7.5 Gy whole-body irradiation (LD50/30) and/or of radioprotecting compound (WR-2721) on the retention and elimination of 144Ce were investigated. It was stated that in the first three days there was an increase in the deposition of 144Ce after whole-body irradiation and upon treatment with radioprotective compound WR-2721.

[Decorporation of radionuclides investigations on the pharmacokinetics of DTPA by means of its decorporating effect on 144Cer (author's transl)]. / Dekorporation von Radionukliden. Uber die Eliminierung von inkorporiertem 144Cer mittels Zn-DTPA bei normaler und gestörter Nierenfunktion.

The influence of Zn-DTPA on the retention of 144Cer in several organs of the rat was investigated 4 days after 144Cer application either with intact or with prevented renal excretion. As the 144Cer activity mobilized from the liver is recovered in gut and faeces an excretion of DTPA bount 144Cer with the bile can be assumed. In animals with impeded renal function an amount of 144Cer is accumulated in blood and extracellular water which corresponds to that mobilized from the skeleton and is normally excreted with the urine.

Studies on the lysosomal binding of 141Ce, 239Np, 239Pu and 241Am in rat and Syrian hamster liver using carrier-free electrophoresis.

The binding of 141Ce, 239Np, 239Pu and 241Am in the liver of rats and Syrian hamsters, following injection in essentially monomeric form, was analyzed by carrier-free electrophoresis at 4-9 days and several months after radionuclide injection. In contrast to density gradient methods lysosomes can be clearly separated from other cell organelles by carrier-free electrophoresis. These, and previous results from this and other laboratories confirm that lysosomes are the main initial binding site for these four radionuclides in the livers of rats and Syrian or Chinese hamster. Light microscopic autoradiography showed that at all the time intervals studied 241Am was more or less uniformly distributed in the liver of all three species. Thus, the changes in the electrophoretic pattern of the nuclides, observed at later time periods in hamsters, cannot be explained by gross redistribution phenomena such as accumulation in macrophages.

The influence of age on the effectiveness of DTPA in reducing 141Ce retention in rats.

The influence of age on the effectiveness of chelation treatment in reducing retention of radioactive cerium was studied in two- and six-week-old albino rats. 141Ce was administered intraperitoneally, followed immediately and after 24 and 48 hours by intraperitoneal administration of the tri-sodium calcium salt of diethylenetriaminepentaacetic acid--Na3(CaDTPA) at 380 mumol/kg body weight. The whole-body retention was determined 2, 4 and 6 days after radiocerium administration, when the animals were killed and the organ retention was determined. The chelation therapy significantly reduced the whole-body retention of radiocerium. This treatment was however twice as effective in older as in younger animals.