W. Moore

Comparison of 115mcadmium retention in rats following different routes of administration

Abstract Whole body retention studies of 115m Cd were carried out on rats following four different routes of administration: oral, inhalation, intraperitoneal, and intravenous. The retention curve for each route of administration was divided into two components. The first component reflected the initial rapid clearance of 115m Cd primarily by the gastrointestinal tract and the second component indicated the absorption and turnover of 115m Cd. Extrapolation of the second component to the intercept gave initial absorption values of 93%, 91%, 41%, and 2.3% for intraperitoneal, intravenous, inhalation, and oral routes, respectively. Immediately after inhalation exposure, 9.7% of the total inhaled Cd was present in the lungs. The route of administration did not significantly influence the rate of elimination and biological half-life of the second component of the whole body retention curve.

Gastrointestinal absorption of different compounds of 115mcadmium and the effect of different concentrations in the rat

Abstract The absorption and retention of three different compounds of 115mcadmium and the effects of variations in concentration were studied in female rats. After a single oral dose, the chloride, sulfate, and acetate forms of 115mCd did not significantly influence the absorption, retention, or distribution of the 115mCd in the tissues. The only organs containing significant amounts of 115mCd were the liver, kidney, and gastrointestinal tract. Increases in concentration of cadmium resulted in more cadmium being absorbed from the gastrointestinal tract, although the amount absorbed was not proportional to the increase in concentration.

Oral toxicity of methylcyclopentadienyl manganese tricarbonyl (MMT) in rats

Abstract Rats were given a single oral dose of MMT diluted in Wesson Oil. Eight groups of animals were used and the dosages varied from 15 to 150 mg/kg body weight. Necropsies were performed and tissues were taken for histopathological and Mn determinations from animals dying during the study and from a selected number of animals euthanatized at the end of the study. The LD 50 14 was 58 mg MMT/kg body weight. Histopathological changes were found in the lungs, liver and kidney. The severity of the changes was related to the dose. Concentrations of Mn in selected tissues were elevated in animals dying from exposure. At 14 days post ingestion, the Mn concentrations had fallen to approximately normal values.

Biological fate of a single administration of 191Pt in rats following different routes of exposure.

Abstract The retention, tissue distribution, and excretion of 191 Pt in adult rats was determined following oral, intravenous (IV), and intratracheal administration. The highest retention was obtained following IV dosing, and lowest retention (less than 0.5%) occurred after oral dosing. Tissues containing the highest concentrations of 191 Pt following IV administration were the kidney, adrenal, spleen, and liver. Following a single oral dose, almost all of the 191 Pt was excreted in the feces due to nonabsorption, whereas after IV dosing, similar quantities were excreted in both the urine and feces. Following IV dosing of pregnant rats, 191 Pt was found in all the fetuses; however, the amount was small.

Fucoidan: Its Binding of Lead and Other Metals

Lead in its ionized form is a hazard to the body, therefore, rapid conversion of lead into a non-ionized form is of prime importance in the treatment of lead poisoning. Lead poisoning has normally been treated with chelating agents such äs ethylene-diamine-tetraacetic acid (EDTA) and penicillamine (PCA). These chelating agents are indeed highly effective in treatment ofacute lead poisoning. However, they have not been proven so in the treatment of chronic cases, or in the maintainance of low blood-lead levels among workers who are continuously exposed to lead. The use of PCA assists in the mobilization of lead, however, large doses are required and it also causes an excessive elimination of copper (Mj^sser and Bessman 1960); thereby decreasing its potential usefulness in lead poisoning. EDTA, a synthetic polyaminoacid has proved more promising in the alleviation of metal poisoning, although it too binds other metal ions besides those which require elimination from the body. Also, it does not give prompt relief of lead colic (Belknap and Perry 1954) and it is potentially nephiotonic and thus an overdose or prolonged treatment can cause nephrosis, which may or may not clear after therapy is discontinued.

Altered function and histology in guinea pigs after inhalation of diesel exhaust

Health effects of inhaled diesel engine exhaust were evaluated in infant guinea pigs following 4 and 8 weeks of exposure. Animals were exposed to 1 part exhaust diluted by 13 parts clean air for 20 hr/day, 7 days/week. Lung function, electrocardiogram, growth rate, and histopathology were assessed following exposure. After 4 weeks, animals exposed to irradiated exhaust, showed a 35% increase in pulmonary air flow resistance, and a small but significant decrease in heart rate. Necropsy, after 8 weeks, showed exhaust exposed animals to have black discoloration of the lungs and increased lung to body weight ratios. Microscopic examination of the lungs from these animals revealed black particulate material in the cytoplasm of alveolar macrophages and in draining lymph nodes.

The binding of lead by a pectic polyelectrolyte

The naturally occurring polyelectrolyte, pectate, was studied for its ability to bind divalent metal cations, with specific reference to lead and calcium. Studies were carried out in vitro by ultrafiltration and in vivo by the ligated intestinal loop technique using rats. By means of the efficiency of ion-exchange reactions with divalent cations, the order of preferential binding was established for pectate. This polyelectrolyte had the greatest affinity for lead with relatively little binding of calcium. Studies in vivo demonstrate up to an 87% reduction in the amount of lead absorbed by the rat when using pectate. It was concluded that this naturally occurring nontoxic polyelectrolyte is a suitable binding agent for lead and that the insignificant binding of calcium is an important criteria for biological and clinical application. The high biological activity of this compound depends on position and availability of functional groups for the ion-exchange process, and viscosity of the solution.

Exposure of laboratory animals to atmospheric maganese from automotive emissions

Abstract Rats and hamsters were exposed eight hours/day for 56 consecutive days to automotive emissions containing increased concentrations of Mn particulate which resulted from the use of a fuel additive, methylcyclopentadienyl manganese tricarbonyl. The exhaust gases were generated by using a 1972 Chevrolet 350 CID engine dynamometer system. The exhaust was diluted and the average concentration of Mn particulate in the irradiated animal exposure chambers was approximately 117 μg/m 3 . No gross changes in general condition or appearance were observed in any of the animals. Microscopic examination of tissues from the animals showed changes related to the exhaust emissions and no changes were found which could be solely attributed to the presence of Mn or MMT. Mn concentrations in the tissues from exposed animals were generally elevated.

Biological fate of 103Pd in rats following different routes of exposure

Abstract The retention, tissue distribution, and excretion of 103 Pd in adult rats was determined following oral, intravenous (iv), and intratracheal admission. The highest retention was obtained following iv dosing, and lowest retention (less than 0.5%) occurred after oral dosing. Tissues containing the highest concentrations of 103 Pd were the kidney, spleen, liver, lung, and bone. Following a single oral dose, almost all of the 103 Pd was excreted in the feces due to nonabsorption, whereas after iv dosing, similar quantities were excreted in both the urine and feces. In pregnant rats following iv dosing, 103 Pd did not readily move across the placental barrier, and statistically significant amounts of 103 Pd were not found in all the fetuses. Furthermore, 103 Pd was transferred to suckling rats via the dams milk.

Metabolic aspects of methylcyclopentadienyl manganese tricarbonyl in rats.

Whole-body retention, excretion, and tissue distribution of 54Mn were studied in rats following oral and intravenous dosing of methylcyclopentadienyl 54manganese tricarbonyl (MMT). An initial rapid excretion of most of the 54Mn occurred following both routes of exposure. Extraction of the urine and feces after dosing indicated that the MMT was metabolized and that the 54Mn was excreted in the inorganic form. The high levels of 54Mn found in the urine after MMT dosing are not typical of normal Mn excretion. The liver, kidneys, and lungs contained the highest concentrations of 54Mn following administration of MMT. In vitro experiments indicated that MMT was metabolized in the liver, lung, kidney, and to a small extent in the brain. Metabolism of MMT by kidney homogenate supported the hypothesis that biotransformation occurred in the kidney and explains the high levels of urinary excretion of inorganic 54Mn. The whole body retention curves for 54Mn labeled MMT and 54Mn Cl2 were very similar and are consistent with the hypothesis that MMT is rapidly metabolized. Both curves for 54Mn reflect the kinetics of inorganic Mn.