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Biomedical subjects

F Korte

Publications and source records attributed to F Korte.

At least 37 records · Page 2Linked to original sources
PubMed1986

Comparison of methods to test chemicals for side effects on soil microorganisms.

The effects of the test chemicals pentachlorophenol (PCP) and HgCl2 on the bioactivity of microorganisms in three different soils were studied in low and high concentrations (2 and 20 ppm). Bioactivity was measured in long-term experiments (18 weeks) by a threefold application of chemicals to soils of varying moisture content. The selected tests were measurements of ATP, of heat output under aerobic and anaerobic conditions and after amendment with glucose, of soil respiration after the addition of glucose, and Fe(III) reduction. The suitability of each test depends on soil microorganisms, on environmental conditions, and on soil properties. The effects caused by the chemicals were as follows. For the low concentration, stimulation or inhibition were mostly repaired within the observation period. The high concentration mostly induced inhibitions which increased or decreased as a consequence of the repeated application of the chemicals. The effects of chemicals were strongly modified by the soil types: in a soil with high organic matter content, differences to the control were lower than in soils with lower organic matter content. These experiments also indicate that measurement of only one physiological parameter is not sufficient to characterize chemicals ecotoxicologically.

Carbon Dioxide↗
PubMed1986

Factors affecting the uptake of 14C-labeled organic chemicals by plants from soil.

The uptake of 14C from various 14C-labeled organic chemicals from different chemical classes by barley and cress seedlings from soil was studied for 7 days in a closed aerated laboratory apparatus. Uptake by roots and by leaves via the air was determined separately. Although comparative long-term outdoor studies showed that an equilibrium is not reached within a short time period, plant concentration factors after 7 days could be correlated to some physicochemical and structural substance properties. Barley root concentration factors due to root uptake, expressed as concentration in roots divided by concentration in soil, gave a fairly good negative correlation to adsorption coefficients based on soil organic carbon. Barley root concentration factors, expressed as concentration in roots divided by concentration in soil liquid, gave a positive correlation to the n-octanol/water partition coefficients. Uptake of chemicals by barley leaves via air was strongly positively correlated to volatilization of chemicals from soil. Both root and foliar uptake by barley could be correlated well to the molecular weight of 14 chemicals. Uptake of chemicals by cress differed from that by barley, and correlations to physicochemical substance properties mostly were poor.

Adsorption↗
PubMed1986

Bioconcentration potential of organic environmental chemicals in humans.

A list of environmental chemicals detectable in adipose tissue and/or milk of non-occupationally exposed humans is presented. Besides their physiochemical properties (n-octanol/water partition coefficient and water solubility), their acceptable daily intake (ADI) values, production figures, fate in the environment, concentrations in human adipose tissue, and data from total diet studies from market basket investigations are given. Average bioconcentration factors (BCF) of polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), DDT, hexachlorobenzene (HCB), dieldrin, hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH), pentachlorophenol (PCP), and 3,5-di-tert-butyl-4-hydroxytoluene (BHT) in human adipose tissue are calculated. The bioconcentration factors (wet wt basis) of these compounds are between 3 and 47 times higher in humans than in rats. The environmental chemicals are divided into three groups in respect to their bioconcentration factors in human adipose tissue: group I, high BCF (greater than 100); group II, medium BCF (10-100); and group III, low BCF (less than 10). The bioconcentration factors are useful for hazard assessment of chemicals to humans.

Adipose Tissue↗
PubMed1986

Review of analytical methods for identification and quantification of cannabis products.

About 100 recently published original papers, reviews, books and other communications concerning cannabis (hashish, marijuana) constituents have been reviewed with the aim of summarizing the status of analytical detection and quantitation. Detailed protocols of standard analytical methods are compared in order to recommend uniform methods for field and forensic samples and also to provide guidance to less experienced analysts in countries where cannabis sativa occurs (T. Maylon.In Big Deal: The Politics of the Illicit Drug Business, the Cannabis Commodity Market, pp. 63-107. Guernsey, London.). Because of its importance, there has been an increasing number of investigations of the chemical, botanical, pharmacological, clinical and sociological aspects of the marijuana (hashish) problem. Since analytical techniques have improved substantially during the last 10 years, many papers have been published containing a variety of methods for detection and quantification of cannabis constituents. Since the analytical situation is becoming increasingly confused and because many of the journals are unavailable in less developed countries, the aim of this paper is to give an overview of existing analytical techniques and to attempt to distinguish practical and effective methods from those which are complex or which provide questionable results.

Cannabinoids↗
PubMed1986

Assessment of the persistence of hexachlorobenzene in the ecosphere.

Various degradation tests were carried out to assess the persistence of hexachlorobenzene (HCB) in the ecosphere. HCB was irradiated with light of various wave-lengths in organic solvents and in water, partly after addition of H2O2 or metal oxides. Photolysis to various dehalogenated products occurred at different rates, depending on concentration and irradiation time; HCB adsorbed on a silica gel was mineralized by light to CO2. A negligible amount of 14C-labelled HCB was mineralized to 14CO2 in various biodegradation tests. In an outdoor lysimeter experiment, 14C residues were found in all parts of wheat plants grown from seeds treated with 14C-HCB. Besides the parent compound and bound residues in plants and soil, very small amounts of soluble polar metabolites were present in the plants; the main product of this group, isolated from roots, was conjugated pentachlorothiophenol. Wheat grown in soil with 14C-HCB residues contained unchanged HCB and bound residues.

Biodegradation, Environmental↗
PubMed1985

Formation and fate of bound residues of [14C]benzene and [14C]chlorobenzenes in soil and plants.

Outdoor experiments with [14C]hexachlorobenzene, [14C]pentachlorobenzene, [14C]1,2,4-trichlorobenzene, and [14C]benzene in soil-crop systems indicate that the formation rate of bound residues in soil and plants, expressed as bound residues in percentage of total residue in the sample, decreases with increasing number of chlorine in the molecule and, thus, with increasing chemical stability. The time course of formation and fate of bound residues in soil and plants is characterized by a very slow decrease of residue levels in soil, indicating that biodegradation of bound residues hardly exceeds their reformation from the parent compound during one vegetation period, and by a decrease of residue levels in plants. The portion of bound residues as compared to the total residue increases with time, indicating that bound residues are more persistent than the parent compounds and their soluble metabolites; benzene is an exception. Cress plants, in general, contain less bound residues than do barley plants. Again, benzene is an exception. In deeper soil layers, soil-bound residues occur also. The ratio between bound and extractable residues does not differ to a larger extent between the soil layers.

Benzene↗
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↗
PubMed1984

Polychlorinated biphenyls (PCBs) in the marine environment, particularly in the Mediterranean.

Polychlorinated biphenyls (PCBs) possess a low water solubility, a high n-octanol/water partition coefficient, and a high persistence, particularly those which are highly chlorinated. Because of these properties they are bioaccumulated in many organisms in the environment. PCBs are still manufactured industrially and used in the Mediterranean countries (e.g., Italy, Spain, and France). Production figures for these countries and for the FRG, the United Kingdom, and the United States between 1973 and 1979 are given. The concentrations of PCBs in marine air, water, sediments, microplankton , algae, mussels, fish, and other marine organisms including seabirds from the Mediterranean area are reviewed and compared with PCB concentrations in marine samples from non-Mediterranean regions. Levels of PCBs in seawater are highest in the western and central Mediterranean. The data for mussels and fish give a clear indication that the PCB levels are higher in the Northwest and the Tyrrhenian Sea than in the eastern Mediterranean. The FDA in June 1979 set 2 mg/kg as the temporary maximum concentration for PCBs in fish and shellfish. The PCB residues in some fish from the northwestern Mediterranean and Tyrrhenian Sea and in some mussels from the Adriatic Sea are higher than this limit. The amount of PCBs ingested via food by the Mediterranean population is unknown.

Air Pollutants↗
PubMed1983

Fate of chemicals in plant-soil systems: comparison of laboratory test data with results of open air long-term experiments.

Three laboratory short-term test systems were used to determine volatilization rates, mineralization rates, and conversion rates of 14 14C-labeled chemicals in soils or soil-plant systems. The chemicals covered a wide range of water solubility, vapor pressure, chemical stability, and biodegradability. In order to compare the data obtained with the environmental behavior of the respective chemicals, data from an outdoor experimental setup which had been shown to give residue data within the range limits of field conditions were used. Volatilization rates, mineralization rates, and conversion rates obtained in the laboratory were correlated to those found under outdoor conditions. Based on these correlations, predictions of field residues were made. The predicted values for total field residues were comparable to those found experimentally with the exception of two chemicals. The prediction of residues of unchanged parent compounds in the field was less satisfactory. The reasons for differences observed are discussed.

Environmental Pollutants↗
PubMed1983

Elimination- and biodistribution studies of [14C]dodecylbenzene sulfonate in rats, following low dosing in the daily diet and a single i.p. administration.

14C-labelled sodium dodecylbenzene sulfonate (DBS) was administered daily in the diet at a concentration of 1.4 mg/kg to male rats for 5 weeks. From the total uptake (1.213 +/- 0.08 mg/animal) of DBS, 81.8% was excreted during the dosing period; 52.4% in feces and 29.4% in urine. Low levels of [14C]DBS-derived residues were detected in all tissues analyzed on day 35 of the experiment. Following 1 week on normal diet only 7.8% of the nominally stored amount of 14C was found in the excreta. Single i.p. application of 0.385 mg [14C]DBS/rat (2.26 +/- 0.15 mg/kg body wt.) resulted in a total elimination of 94.5% within 10 days. 84.7% of the dose was eliminated in the first 24 h. All fecal and renal [14C]DBS-derived activity consisted of highly polar metabolites.

Administration, Oral↗