Swiss chard, field-grown on soil amended with 100 dry tons per acre of municipal sewage sludge from Washington, DC, was fed to guinea pigs for 28 days. Control animals were fed Swiss chard grown on unfortified soi. Forty-one elements were determined in the sludge, the plant material, and liver, kidney, muscle, adrenal, and spleen tissues by neutron activation and other methods. Elevated concentrations of several elements found in the Swiss chard grown on the sludge-soil mixture also appeared at higher levels in certain of the animal tissues. These included antimony in adrenal, cadmium in kidney, manganese in liver tissues, and tin in several tissues. The animals showed no observable toxicological effects.

Adrenal Glands↗

PubMedDate not supplied

Heavy metal residues in plants cultivated on and in small mammals indigenous to old orchard soils.

Six vegetables and millet were grown on the site of an old orchard which had received heavy applications of lead arsenate and organic mercury fungicides for many years. Carrots and millet absorbed about 7 ppm (dry weight) of lead, the other crops containing smaller concentrations. Concentrations of arsenic and mercury showed only modest increases in crops grown on the orchard soil as compared to controls. Lead concentrations in kidney, liver, and bone tissue of meadow voles trapped in two old orchards were markedly higher (up to 300 ppm in bone) than control animals (up to 33 ppm). Intranuclear inclusion bodies diagnostic of lead poisoning were found in the renal epithelial cells of the proximal convoluted tubules in voles from lead arsenate treated orchards.

Animals↗

PubMedDate not supplied

Selenium in particulates and gaseous fractions of smoke from cigarettes prepared from tobacco grown on fly-ash-amended soil.

Cigarettes prepared from tobacco grown in pots of soils amended with soft coal fly ash were smoked, and the mainstream and gaseous fractions were analyzed for total selenium concentration. Fly-ash-grown and control (soil-grown) tobaccos contained, respectively, 0.79 and 0.03 ppm selenium. The quantities of selenium (ng per cigarette) found in the mainstream particulate and gaseous fractions were, respectively, 62.4 and 246.0 for the fly-ash-grown and 8.6 and 12.0 for the control treatments. Studies of the absorption, retention, effects, metabolism, and excretion of selenium in the body are reviewed.

Carbon↗

PubMedDate not supplied

Chemoprevention with triphenylselenonium chloride in selenium-deficient rats.

Cancer chemoprevention by high levels of selenium, including compounds like sodium selenite or selenomethionine, is generally not accompanied by increases in known selenoenzymes. There has been no information on whether selenoenzymes are obligatory mediators of the anticarcinogenic effect of selenium. Our previous experience with triphenylselenonium chloride suggests that it might be an ideal agent for studying selenium chemoprevention while simultaneously precluding the synthesis of selenoenzymes. Triphenylselenonium chloride has excellent tumor inhibitory activity but does not support the repletion of selenoenzymes in animals that have been deprived of a bioavailable form of selenium. In the present experiments, we evaluated the efficacy of mammary cancer protection by this compound in rats fed either a selenite-deficient (< 0.01 ppm Se) or selenite-adequate (0.1 ppm Se) diet. We also measured the activities of liver glutathione peroxidase and thioredoxin reductase as markers of selenium bioavailability in these different treatment conditions. In carcinogen-treated control animals not receiving triphenylselenonium chloride, mammary tumor incidence and the total number of tumors were similar between the selenite-deficient and selenite-adequate groups. Thus the correction of selenium deficiency by the addition of 0.1 ppm Se as selenite did not have detectable anticarcinogenic effects. Supplementation of triphenylselenonium chloride at a level of 30 ppm Se suppressed mammary tumorigenesis by approximately 50% regardless of dietary selenium nutritional status. However, this supplement had little effect on tissue selenium levels and did not increase liver glutathione peroxidase or thioredoxin reductase activities. In contrast, a level of 0.1 ppm Se as selenite did not affect mammary tumorigenesis but markedly increased tissue selenium concentrations and selenoenzyme activities. It is concluded that triphenylselenonium chloride does not release inorganic selenium for selenoprotein synthesis and that its anticancer activity involves mechanisms that are probably intrinsic to the compound. This study also shows for the first time that selenium chemoprevention is possible in an environment of severely depressed selenoenzyme expression. Thus selenium chemoprevention efficacy can be separated experimentally from selenoprotein synthesis using this model system.

Animals↗

PubMedDate not supplied

Gas chromatographic determination of fenvalerate insecticide residues in processed tomato products and by-products.

The results of a 5-laboratory collaborative determination of residues of the synthetic pyrethroid insecticide fenvalerate in tomato products are presented. Tomatoes from plants treated in the field at 2-4 day intervals (13 foliar applications) were processed into chopped fresh tomatoes, canned quarters, juice, paste, and the by-product skins plus seeds. Gas chromatographic analysis of the commodities for fenvalerate showed the fresh produce to contain 0.26 ppm, and the skins plus seeds contained 1.9 ppm. Residues were barely detectable in canned peeled quarters and juice, but averaged 0.12 ppm for paste, the concentration product of juice. High residues were associated with the skin content of the product. Five laboratories using modifications of the same analytical technique obtained good collaborative agreement.

Chromatography, Gas↗

PubMedDate not supplied

Use of amprolium for the control of coccidiosis in pheasants.

Amprolium administered in feed during the first 4 weeks of life at a level of 0.0175% protected pheasants against three major pathogenic species of coccidia (Eimeria colchici, E. duodenalis, and E. phasiani) when they were exposed at 2 weeks of age. The difference was significant when mortalities were compared between medicated infected (3%) and unmedicated infected (35%) pheasants. The manufacturer's proposed level (0.0175%) and twice the proposed level (0.0350%) of amprolium had no significant effect on weight gains or mortality in the safety trial. Amprolium residues found in the muscles and livers of pheasants that received either level of amprolium did not exceed the tolerance levels for chickens and turkeys permitted by the U.S. Food and Drug Administration.

Amprolium↗

PubMedDate not supplied

Triphenylselenonium and diphenylselenide in cancer chemoprevention: comparative studies of anticarcinogenic efficacy, tissue selenium levels and excretion profile.

The objectives of the present study were to evaluate the cancer chemopreventive activity of triphenylselenonium chloride and diphenylselenide and to investigate the pharmacology of these two compounds with respect to their tissue accumulation and excretion profile. Although both phenyl selenide derivatives are related to each other structurally, they differ substantially in their intrinsic chemical properties. Triphenylselenonium is positively charged and amphiphilic, while diphenylselenide is uncharged and lipophilic. With the use of either the DMBA- or MNU-induced mammary tumor model in rats, triphenylselenonium was found to have superior chemopreventive efficacy compared to diphenylselenide. Both reagents were present at 30 ppm Se in the diet. At the time of sacrifice (22 weeks post-carcinogen), triphenylselenonium produced only minimal accumulation of selenium in the liver, kidney, mammary gland and plasma. In contrast, diphenylselenide caused a 2- to 3-fold elevation in selenium concentration depending on the tissue examined. Thus even though diphenylselenide was able to increase total selenium in tissues, it was less active in cancer protection. Fecal excretion following a single oral dose of triphenylselenonium (equal to the amount consumed in 1 day by an animal fed a diet containing 30 ppm Se) was approximately 78% and 8% of the dose during the first and second day, respectively, suggesting that the bulk of the dose was not absorbed. With diphenylselenide, fecal excretion was about 6% and 30% of the dose during the first and second day, and about 20% of the dose was excreted in the urine in each of the 2 days. This observation suggests that a large proportion of the diphenylselenide dose was absorbed and that urinary excretion was a major route of elimination for diphenylselenide once it was absorbed. Further studies are needed to clarify the basis for the differential effects of these phenyl selenide derivatives.

Animals↗

PubMedDate not supplied

Activities of structurally-related lipophilic selenium compounds as cancer chemopreventive agents.

The present study compared the effects of four lipophilic forms of selenium with regard to cancer chemopreventive activity, tissue selenium accumulation, and bioavailability for synthesis of a selenoprotein. These reagents included methylphenyl selenide, diphenyl selenide, triphenyl-selenonium chloride, and p-xylylbis(methylselenide). The maximum tolerable dose (added in the diet) for each of these compounds was 5, 30, > 200, and 5 ppm Se, respectively. Because of differences in their tolerance, the cancer chemopreventive activities (in a methylnitrosourea-induced mammary tumor model in rats) of all 4 compounds were assessed at the 5 ppm Se level. Methylphenyl selenide was the most effective--79% inhibition, followed by p-xylylbis-(methylselenide)--66% inhibition, triphenylselenonium chloride--27% inhibition, and diphenyl selenide--10% inhibition. With respect to tissue selenium levels, p-xylylbis(methylselenide) produced the highest accumulation of selenium (approximately 3-fold increase in liver and kidney, 14-fold increase in mammary gland); methylphenyl selenide and diphenyl selenide showed more modest increases (1.5-fold or less in liver and kidney, 2.5-fold or less in mammary gland); while triphenylselenonium chloride resulted in no change. Highest bioavailability of selenium was observed for p-xylylbis(methylselenide), which was followed closely by methylphenyl selenide. Bioavailability was very low with diphenyl selenide, and undetectable with triphenylselenonium chloride. The chemical reactivities of these different selenium compounds are discussed in relation to the biological effects reported here.

Animals↗