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Biomedical subjects

F Korte

Publications and source records attributed to F Korte.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1977

Epoxidation of aldrin to exo-dieldrin by soil bacteria.

Twenty-two strains of soil bacteria, including representatives of the genera Bacillus, Micromonospora, Mycobacterium, Nocardia, Streptomyces, Thermoactinomyces, and Pseudomonas and 10 unidentified gram-negative, motile, rod-shaped bacteria, were shown to degrade aldrin to its epoxide dieldrin. In every case, the exo-stereoisomer of dieldrin was produced exclusively.

Aldrin↗
PubMed1976

Contributions to ecological chemistry CVII1. Fate of lindane-14C in lettuce, endives and soil under outdoor conditions.

In seven successive outdoor experiments, lindane-14C was applied to lettuce or endive leaves as an aqueous formulation (about 12 mg on 20 plants for each experiment). The growing periods varied between 21 and 37 days. After this time, between 4.5% and 13.9% of the applied radiocarbon was recovered from the plants. Conversion rates to soluble metabolites as well as to unextractable residues appeared to be dependent on weather conditions. During the summer months, the radiocarbon in plants consisted of 36% soluble metabolites and of 30% unextractable residues (average of 4 experiments); in autumn, the conversion rates were much lower. The following metabolites were identified in both plant species by gas chromatography/mass spectrometry: a polar group (a free trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, conjugates of the latter two compounds, and unidentified water-soluble products) amounting to 35% of the radioactivity in plants cultivated in summer, and a nonpolar group (a dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,5, and/or 1,2,4,5-tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, and gamma-pentachlorocyclohexene) amounting to 1% of the radioactivity in plants cultivated in summer. The 20 cm top-soil layer had about 14% of the total radioactivity applied to all plants. Six % of the radioactivity recovered from the soil was soluble metabolites and about 50% was not extractable. The soluble metabolites comprised a polar group (free and conjugated 2,3,4,6-tetrachlorophenol, pentachlorophenol, and unidentified water soluble products) amounting to 5% of the radioactivity in the soil as well as a nonpolar group (1,2,3-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5 and/or 1,2,4,5-tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, and gamma-pentachlorocyclohexene) amounting to 1% of the radioactivity in the soil.

Biodegradation, Environmental↗
PubMed1976

Contributions to ecological chemistry CXII1. Balance of conversion of buturon-14C in wheat under outdoor conditions.

The urea herbicide buturon (N-[p-chlorophenyl]-N'-methyl-N'-isobutinyl-urea), 14C-labeled, was sprayed on winter wheat as an aqueous formulation (2.98 kg/ha) under outdoor conditions. Upon harvest (three months after application), a total of 49.2% of the applied radiocarbon was recovered: 2.0% in the plants, 46.9% in the soil, and 0.3% in the leaching water (depth greater than 50 cm); less than 0.1% was in the grains (0.464 ppm). Only about half of the radioactivity present in plants could be recovered under mild extraction conditions; about half of this was unchanged buturon. In straw and husk extracts, the following metabolites were identified by gaschromatography/mass spectrometry:N-(p-chlorophenyl)-N-methyl-O-methyl-carbamate (metabolite I), N-phenyl-N'-formyl-urea (metabolite II), two unstable metabolites giving (p-chlorophenyl)-isocyanate upon purification (metabolites III and IV), N-(p-chlorophenyl)-N'-methyl-N'-isobutenylol-urea (metabolite V), p-chloroformanilide (metabolite VI) and biologically bound p-chloroaniline (metabolite VII). In the root and basal stem extract, the following metabolites were identified by gas chromatography/mass spectrometry: N-(p-chlorophenyl)-O-methyl-carbamate (metabolite VIII) and N-(p-chlorophenyl)-N'-methyl-urea (metabolite IX).

Chromatography, Gas↗
PubMed1976

Contributions to ecological chemistry, CXIV1. Fate of 2,2'-dichlorobiphenyl-14C in rats upon long-term feeding.

Each of five male and five female rats was orally dosed with 49.2 mug 2,2'-dichlorobiphenyl-14C daily for 42 days. After 36 days, the radioactivity in the body reached a plateau level, and male rats had excreted 84.5% of the applied radioactivity, females 87.9%; the residues in most organs were below 0.2 mg/kg. The daily excreted radioactivity after 50 days had decreased to 0.7% (males) and 0.5% (females) of the daily dose; the total excretion was then 86.2% (males) and 89.4% (females) of the total applied dose, and the organs contained less than 0.1 mg/kg. More than 90% of the radioactivity in the excreta was due to metabolites (one monomethoxy-, three monohydroxy-, three dihydroxy-, one trihydroxy-2, 2' -dichlorobiphenyl, conjugates, and a dechlorinated derivative).

Animals↗