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F Korte

Publications and source records attributed to F Korte.

At least 37 records · Page 2Linked to original sources
PubMed1985

Interactions in the fate of chemicals in terrestrial systems.

In outdoor lysimeters, [14C]atrazine (0.9 mg/kg dry soil), [14C]atrazine combined with the detergent n-dodecylbenzenesulfonate (0.9 and 10 mg/kg, respectively), [14C]n-dodecylbenzene-sulfonate (10 mg/kg), and [14C]n-dodecylbenzenesulfonate combined with atrazine (10 and 0.9 mg/kg, respectively) were applied to soils. Maize was grown in the first year and barley in the second year. n-Dodecylbenzenesulfonate increased the mobility of atrazine and its metabolites in soil as well as its leaching into water, its uptake by maize plants, and its volatilization from soil. Atrazine had a negative influence on mineralization, mobility in soil, leaching, plant uptake by both species, and binding rates of radiocarbon derived from the surfactant in soil and plants. The results were confirmed by short-term laboratory tests. Whereas the effects of the detergent on the fate of atrazine and its conversion products were apparent only in the first growing season, those of atrazine on the fate of detergent-derived residues could also be observed in the second year due to the persistence of atrazine in soil.

Atrazine↗
PubMed1985

Influence of benzene on the phytoplankton and on Daphnia pulex in compartments of an experimental pond.

Benzene, with initial concentrations of 100 and 50 mg per liter, was dosed in duplicates into four compartments of a small pond. The decrease of chemical concentration in the water was exponential with a mean half-life of 4.7 +/- 0.9 days. Following benzene application, the phytoplankton density and diversity slightly increased relative to the controls. Both concentrations were lethal for the daphnids present. During 24-hr in vitro tests with Daphnia pulex (initial benzene concentrations less than 50 mg per liter), a direct correlation between mobility and decreasing chemical concentration was observed.

Animals↗
PubMed1985

The role of the chimpanzee in the evaluation of the risk of foreign chemicals to man.

Various species of laboratory animals are used to evaluate the efficacy and safety of drugs in man. However, the extrapolation of data from animals to man is often complicated by species differences in the disposition of foreign chemicals. The findings of comparative metabolism studies are used to illustrate species differences in metabolic pathways, rates of biotransformation, kinetics, and excretion routes. Biochemical and structural consequences of the significant differences in enzyme induction between rodents and primate species are discussed. Among the primates, the chimpanzee has been shown to be the most closely related to man not only in the disposition of xenobiotics, but also in the aspects of endocrinology, serology, and immunology. It would, therefore, be the best possible model to predict the fate and effects of foreign chemicals in man. Due to the limited availability of chimpanzees, however, they can only be used for the evaluation of the most critical chemicals and drugs. Comparative metabolism and disposition studies, e.g., of compounds representative of classes of chemicals in chimpanzees and other animals. Only when the pertinent differences between the selected test species and man are known can correct extrapolations to man be made.

Animals↗
PubMed1985

Accumulation of pollutants in fish.

The amount of radioactivity which derived from 14C-labeled pollutants was determined in liver, kidney, intestine, blood, muscle and gills of carp, exposed for 6, 24 and 72 hr to high external concentrations of urea, methanol, atrazine and PCP. The results allowed one to calculate roughly the uptake rate for these compounds. It was low for urea (0.055 micrograms/g per hr), higher for methanol (0.12) and atrazine (0.16) and highest for PCP (1.5). The bioaccumulation factors (BFs) were determined for the different substances and organs. They correlated with the hydrophilic-lipophilic nature of the chemicals. The more lipophilic the substances the more accumulation occurred in the liver. PCP accumulated the most. BF was 300-400 in most tissues except muscle where it was quite low. The BF was 3-4 for atrazine in liver, kidney and intestine, but just 1 in blood, muscle and gills. There is some evidence that the BF for methanol equals 1 in liver, kidney, gills and intestine. It is less than 1 in blood and muscle. Urea was equally distributed in all organs and in the external medium.

Animals↗
PubMed1979

Fate of chloroalkylene-9-14C in carrots, sugar beets, and soil under outdoor conditions.

Immediately after application of chloroalkylene-9-14C to soil (1.32 ppm, based on dry weight of soil in the upper layer of 0 to 10 cm) under outdoor conditions, carrots were sown; in the following year, sugar beets were grown. About 80% of the radioactivity applied volatilized within one vegetation period. Most of the remaining radioactivity was still in the upper soil layer; 0.8% had dispersed to a depth of 40 cm, and 3.3% was taken up by the carrot plants. In the second year, no more decreases of soil residues was observed; uptake by sugar beets was 0.1% of the applied radioactivity. In the first year, the residues in the upper soil layer consisted of 41% unchanged chloroalkylene-9, 19% soluble metabolites, and 40% unextractable residues; the amount of unextractable residues rose to 68% in the second year. The following conversion products were characterized in the soil extracts: a monohydroxylated dichlorobiphenyl, a monomethoxylated dichlorobiphenyl, and two isomeric monohydroxylated, monoisopropylated dichlorobiphenyls; in carrot roots, a monomethoxylated dichlorobiphenyl was detected. Conjugates occurring in the soil yielded, after acid hydrolysis, a monohydroxylated dichlorobiphenyl among other compounds.

Hydrolysis↗
PubMed1979

Mass spectrometry and stability of t-butyldimethylsilylethers of some estrogens and androstanes.

In addition to using radioimmunoassays for the determination of estrogens and other steroids, the possibility of using mass fragmentography for analysis was investigated. t-Butyldimethylsilyl chloride was selected as a reagent for derivatisation because it forms rather stable silylethers. In all the mass-spectra obrained from the steroid derivatives, one pronounced peak suitable for mass fragmentography was always present. Some of the spectra of the investigated estrogens, as well as testosterone, 3 alpha-hydroxy-5 alpha-androstan-17-one and 17 alpha-methyl-17 beta-hydroxy-5 alpha-androstan-3-one are discussed. The stability of various t-butyldimethylsilylethers and the rate of enolization of testosterone and progesterone in the presence of the silylation-agent under different conditions were established.

Androstanes↗
PubMed1979

Fate of 2,5,4'-trichlorobiphenyl in rats.

1. Following the administration of daily oral doses (1 mg/kg) of 2,5,4'-trichloro-[14C]biphenyl to rats for 14 days, the compound was rapidly excreted, only small amounts (3--4%) being stored in the organs. 2. The majority of the biphenyl was metabolized (greater than 85%) and the major metabolites excreted were identified as hydroxy-, dechloro- and conjugated derivatives.

Animals↗
PubMed1978

[Polychlorinated biphenyls (PCB) in food. The situation in the Federal Republic of Germany (author's transl)].

In a coordinated research program of the Federal Ministry of Research and Technology (BMFT), a screening study was carried out with representative samples. In spite of rather large ranges of PCB concentrations, the most important food-stuffs show clearly defined clusters with mean values of approx. 0.005 microgram/g in low fat food components of plant origin such as cereals or potatoes, approx. 0.05 microgram/g in vegetable fats, approx. 0.3 microgram/g in fat from milk, butter and cheese, approx. 0.15 microgram/g in animal fat, approx. 0.03 in chicken eggs and approx. 10 microgram/g in fish fat. Considering the mean diet in the FRG, a daily PCB intake of about 29 microgram from animal fat and of 6 microgram from the other food-stuffs results. The total intake of about 35 microgram per day and capita is almost the same as the figure conditionally suggested by the WHO as the acceptable daily HCB (hexachlorobenzene) intake.

Animals↗
PubMed1978

Endocrine effects of chlorinated hydrocarbons in rhesus monkeys.

After the rhesus monkey was demonstrated to be a suitable model for man in both metabolic and endocrinological studies, effects of hexachlorobenzene (HCB) and polychlorinated biphenyls (PCB) on the pattern of sexual hormones in cycling female rhesus monkeys were investigated. After confirmed ovulation, four adult female rhesus monkeys were treated during the following cycle with 4 mg/kg/day of HCB, and four other monkeys were treated with the same dose of Clophen A 30. Ovulation was blocked in three PCB-treated and one HCB-treated monkeys. Whereas the levels of luteinizing hormone and follicle-stimulating hormone did not seem to be changed directly by the treatment, low estrogen levels were found during the anovulatory cycles. Studies with PCB- and HCB-treated superovulated rats indicated interaction of the chemicals with ovarian steroidogenesis. Altered hepatic steroid metabolism may also cause low estrogen levels in treated animals.

Animals↗