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  • 1
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Guppy, snail, elodea, and coontail, when exposed to water containing203Hg-labeled phenylmercuric acetate (PMA), readily take up PMA and the PMA uptake is related to the time of exposure and the PMA concentration, the absorbed PMA being mainly converted to inorganic mercury. Ethylmercuric chloride is a minor metabolic product. Mercury-203 is not quickly eliminated from the guppy, elodea, and coontail when they are placed in fresh water, the biological half-life of203Hg residues ranging between 43 to 58 days.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Rats fed diets containing 0.1 percent of three polychlorinated biphenyls (PCBs) (Arochlor 1248, Arochlor 1254, Arochlor 1262) for six weeks show a progressive enlargement of the liver. This liver hypertrophy is attributed to proliferation of the smooth endoplasmic reticulum, development of large membranous concentric arrays, and increase in lipid droplets within the cytoplasm of the affected liver cells. Liver homogenates show increased levels of protein and RNA and reduced concentrations of DNA. Microsomal fractions have increased levels of protein and phospholipids, and reduced levels of cholesterol. Also, there are modifications in the activity of certain hepatic microsomal enzymes. By the sixth week, the animals have progressed from a stimulatory effect on the liver by the PCBs to a stage where regressive hepatic changes are occurring, such as a decreased activity of microsomal enzymes, dissolution of concentric membrane arrays, vesiculation of the endoplasmic reticulum, and accumulation of lipid droplets within the cytoplasm of the affected cells.
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  • 3
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Chemical and physical decontamination procedures for dicofol [1,1′-bis(p-chlorophenyl)-2,2,2-trichloroethanol; Kelthane®], as applied to apples under controlled laboratory conditions, were studied on Red Delicious apple pomace (stems, cores, seeds, and peelings). Oven heating the contaminated pomace at 100°C for 24 hours, with and without excess moisture, removes 59.0% to 81.7% of the total dicofol residues. If the pomace is mixed with dry powdered alkali and heated, the residues are reduced 85.5% to 94.1%. If the pomace is mixed with dry powdered alkali and excess moisture, and heated, the total residues are reduced 98.7% to 99.1%. Vapor washing the pomace with water reduces the dicofol residues from 31.0% to 51.6%. Vapor washing the pomace with isopropanol reduces the dicofol by 65.6%. Cool-air drying, sunlight drying, ultraviolet light drying, and hot-air drying further reduces the total dicofol levels by 43.3%, 30.7%, 24.2%, and 40.6%, respectively, for the water-vapor-washed pomace, and 68.0%, 71.0%, 83.2%, and 94.0%, respectively, on the isopropanol-vapor-washed pomace. Dicofol residues can be effectively reduced on apple pomace by the above physical and chemical decontamination procedures. The decontaminated pomace can be utilized as a valuable feed by-product from apples.
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  • 4
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Nine mallard ducks were raised artificially from eggs and fed the same long-term doses of dieldrin as their parents (0, 4, or 10 ppm); in addition, three ducks from 10 ppm parents were raised on 50 ppm. The parents had been on dieldrin-treated feed for two years. The juvenile ducks were tested at approximately two months of age. Each duck was trained to respond (key peck) differentially to light wavelengths of 552 mµ (S+) and 610 mµ (S−) and, subsequently, was presented 13 different wavelengths, in random order. Differential responding was analyzed for stimulus generalization. No significant differences (p〈.05) were found between the control and treated groups' mean stimulus generalization gradients. Only the group receiving 50 ppm in their feed had a mean whole-brain dieldrin residue significantly larger (p〈.05) than that of the control group. These results indicate that the ingestion of dieldrin, under the test conditions used, does not have a measurable effect on light wavelength discrimination in mallard ducks.
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  • 5
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The uptake and the tissue distribution of ethylmercuric chloride (EMC) by inhalation and oral administration were studied in adult female rats. The pulmonary uptake of EMC linearly increases with the time of exposure and is proportional to the concentration of EMC vapor. With the exception of stomach, intestine, and hair, the tissue distribution of203Hg from pulmonary uptake is quite similar to that from oral administration. The biological halflife of EMC in the organs is longer from pulmonary uptake than from oral administration. Kidney and liver convert EMC to in-organic mercury irrespective of the routes of administration. A small amount of203Hg is found in the fetus, and the fetal liver accumulates more203Hg than the fetal kidney.
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  • 6
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Cyanide markedly affected growth and resting metabolic rate while causing degenerative hepatic necrosis in juvenile rainbow trout (Salmo galrdneri, Richardson). This was revealed during two experiments performed in continuously renewed water at 12.5°C with fish fed a restricted artificial diet and exposed to assayed cyanide concentrations of 0.00, 0.01, 0.02, or 0.03 mg/L hydrogen cyanide (HCN) for 18 days. At 0.02 and 0.03 mg/L, HCN growth was reduced by 40 to 95% after 18 days. At all concentrations, cyanide caused a severe initial repression of specific growth rate, followed by a highly significant increase which was insufficient to compensate for the original repression. Previous exposure to cyanide promoted a higher resting metabolic rate during the six days following exposure, the effect increasing with cyanide concentration. At all concentrations tested, widespread cyanide-induced degenerative necrosis of hepatocytes was observed; it was more intense at higher cyanide concentrations and well established even at 0.01 mg/L HCN.
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  • 7
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The calculated, acute oral LD50 of acephate and methamidophos to dark-eyed juncos (Junco hyemalis) was 106 mg/kg and 8 mg/kg, respectively. Brain cholinesterase (ChE) activity in birds that died after acephate poisoning was depressed 80% below that of control birds. Birds that died of acute methamidophos poisoning had brain ChE depression of 60%. The birds killed by acephate had brain acephate residue concentrations greater than 2 mg/kg and methamidophos concentrations usually greater than 0.25 mg/kg. Eighty percent of the birds killed with methamidophos had brain methamidophos concentrations greater than 0.1 mg/kg. The five-day feeding LC50 for acephate was 1485 mg/kg. Brain ChE activities of birds which died early in the study were less depressed (51.5%) than those which died at a later date (69.6%). Brain residues of acephate and methamidophos were lower in these birds than in the birds of the acute oral LD50 studies. Brain ChE activity returned to normal within three days after the birds received a single sublethal dose of acephate. These studies indicate that the amount of acephate needed to produce the ChE depression found in other investigations in most dark-eyed juncos exposed to forest applications of insecticide is about one-fifth of the LD50; however, in a few birds the ChE activity may be depressed to near lethal levels.
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  • 8
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The effects of copper on the development ofCrassostrea gigas embryos were determined with a 48-hr static bioassay. In filtered, sterilized seawater from Bodega Bay, California, the LC100 was 20μg Cu/L, and the LC50 was 12μg Cu/L. Destruction of the naturally occurring dissolved organic material in the culture water by UV oxidation decreased embryo survival at 10μg Cu/L. The addition to seawater of five organic chelators (ethylenediaminetetraacetic acid (EDTA), sodium citrate, glycine, and oxalate at 1×10−6 M, and humic matter at 2 mg/L) increased embryo survival. EDTA and humic matter were the most effective chelators; EDTA significantly increased survival at 100μg Cu/L and humic matter did so at 40μg Cu/L. The ability of a chelator to increase survival was related to the stability constant of the copper-chelator complex.
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  • 9
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The acute and chronic toxicities of a simulated refinery effluent and its components toMysidopsis bahia were examined. The 96 hr LC50 forM. bahia was 4.7% of the Artificial Refinery Mixture (ARM). The mysid was more sensitive than an estuarine fish and grass shrimp, as well as 17 freshwater organisms previously tested. Fuel oil was the most toxic component of the ARM (96 hr LC50 0.73 mg/l) and contributed disproportionately to the toxicity of the mixture. Chronic exposure to 2.7% of the ARM formulation resulted in growth inhibition by day 8 and reproductive impairment. Long-term exposure to the 96 hr LC10 had deleterious effects on growth and/or reproduction for each component tested.
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  • 10
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Brain and plasma cholinesterase (ChE) activities were determined for mallard ducklings (Anas platyrhynchos) exposed to dicrotophos and fenthion. Recovery rates of brain ChE did not differ between ducklings administered a single oral dose vs. a 2-week dietary dose of these organophosphates. Exposure to the organophosphates, followed by recovery of brain ChE, did not significantly affect the degree of brain ChE inhibition or the recovery of ChE activity at a subsequent exposure. Recovery of brain ChE activity followed the general model Y=a+b(logX) with rapid recovery to about 50% of normal, followed by a slower rate of recovery until normal ChE activity levels were attained. Fenthion and dicrotophos-inhibited brain ChE were only slightly reactivatedin vitro by pyridine-2-aldoxime methiodide, which suggested that spontaneous reactivation was not a primary method of recovery of ChE activity. Recovery of brain ChE activity can be modeled for interpretation of sublethal inhibition of brain ChE activities in wild birds following environmental applications of organophosphates. Plasma ChE activity is inferior to brain ChE activity for environmental monitoring, because of its rapid recovery and large degree of variation among individuals.
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