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Biomedical subjects

B Teichmann

Publications and source records attributed to B Teichmann.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Significance of chemical carcinogens in the atmosphere for carcinogenesis].

After some remarks on air pollution by chemical carcinogens from natural or man-made sources a few figures area given on the production of chemicals and their emission, to characterize the situation. Our little knowledge on the carcinogenic risk from carcinogens in the ambient air is demonstrated with benzo[a]pyrene as an example. The role of nitroaromatic hydrocarbons as possible carcinogenic factors is indicated. We know, that carcinogens exist in the ambient air. Their quantity and sources are partially known. Their activity as a complex is as well unknown as the resulting level of health risk for humans.

Air Pollution↗
PubMed1981

[Screening of chemicals and tests for carcinogenicity - part of comprehensive toxicological investigation].

Screening tests (short-term tests) can be utilized as methods to select suspicious chemicals which should or must be further tested in long-term animal experiments. Up to now long-term animal bioassays rank prominent in predicting possible carcinogenicity of a compound in man even when taking into account all limitations of evaluation and extrapolation of results obtained to man. Any substance which is shown to cause tumors in animals should be considered carcinogenic and therefore to be a potential hazard for man, Distinction between "animal" carcinogens and "human" carcinogens is not justified and should be avoided. Screening of chemicals and testing for carcinogenicity are parts of protective measurements related to primary cancer prevention. In special cases it can be necessary to weigh risk against benefit from a chemical to enable realistic political decisions in the field of health protection.

Animals↗
PubMed1981

Chemical carcinogens: screening, testing, risk assessment for man.

Testing of chemicals for carcinogenic activities is an important part of a comprehensive toxicological test program. Screening tests (short-term tests) can be utilized as methods to select suspicious chemicals which should or must be further tested in long-term animal experiments. Up to now long-term animal bioassays, even when taking into account all limitations of evaluation and extrapolation of results to man, rank prominent in predicting carcinogenicity of a compound in man. Any substance which is shown to cause tumors in animals should be considered carcinogenic and therefore a potential hazard for man.

Animals↗
PubMed1980

Metabolizing activities of postmitochondrial liver fractions (S-9) on benzo[a]pyrene and dimethylnitrosamine.

The mutagenic activity of the carcinogens benz[a]pyrene and dimethylinitrosamine after being metabolised by postmitochondrial liver fractions (S-9) from rats, Syrian hamsters and rabbits was estimated in the Ames' test. The liver donors were pretreated with phenobarbital, 3-methylcholanthrene, PCB (Delor 106) or peanut oil. Parallel to the mutagenicity tests, enzymes of S-9 such as dimethylnitrosamine demethylase and aryl hydrocarbon hydroxylase were estimated and their activity evaluated with reference to the results of the Ames' test.

Animals↗
PubMed1980

Nitrosation of orally administered drugs under simulated stomach conditions.

Of a total of 61 drugs considered to be potentially nitrosatable on the basis of their chemical structure, 7 have indeed been nitrosated in gastric juice at pH 2 and under simulated human stomach conditions, where the pH was varied from about 7 to 2 within 60 min. The 7 nitrosatable drugs were ethambutole, despiramine hydrochloride, clomipramine hydrochloride, phenoxymethyl penicillin, aminophenazone, piperazine diadipate and analgine. Inhibition of nitrosation under simulated stomach conditions was also investigated using ascorbic acid, sulfanilamide, p-aminosalicylic acid and sulfamic acid. The first three agents were effective inhibitors, whereas sulfamic acid stimulated nitrosation within a distinct pH range.

Animals↗
PubMed1979

'Human' and 'animal' carcinogens.

A clarification is made of the meanings of the terms 'human carcinogen' and 'animal carcinogen' in cancer research, cancer prevention and legislative actions. A chemical proven to have carcinogenic activity in animals should be considered to represent a risk to humans. However, non-experts tend to consider that 'animal carcinogens' produce cancer only in animals and can be neglected with regard to the human situation. The use of these terms should thus be avoided or they should be used as standard terms based on generally accepted and available definitions.

Animals↗
PubMed1978

[Action of polychlorinated biphenyls (Kanechlor 500 and Delor 106) and 3-methylcholanthrene on the activity of some rat liver microsomal enzymes].

The influence of 3-methylcholanthrene and two commercially available mixtures of polychlorinated biphenyls (Kanechlor 500 and Delor 106) on the activity of some microsomal rat liver enzymes has been investigated. The studies included the demethylation of ethylmorphine, dimethylnitrosamine, and 4-dimethylaminoazobenzene as well as the investigation of the activity of aryl hydrocarbon hydroxylase and of azoreductase using benzo(a)pyrene and 4-dimethylaminoazobenzene as substrates, respectively. 3-methylcholanthrene induced the aryl hydrocarbon hydroxylase and azoreductase and led to an increase in the demethylation of 4-dimethylaminoazobenzene but not in the ethylmorphine demethylation. The relatively low increase in the dimethylnitrosamine demethylation was not statistically significant. These polychlorinated biphenyls caused a significant increase in all the enzyme activities studied. In most cases Delor 106 was more active than Kanechlor 500. The results are discussed and compared with those of other authors.

Animals↗
PubMed1978

[Test of 0,0-dimethyl (l-hydroxy-2,2,2-trichloroethyl)-phosphonate (trichlorfon) for carcinogenic activity in mice by oral (oesophageal-gastric intubation), intraperitoneal and dermal application (author's transl)].

0,0-Dimethyl(1-hydroxy-2,2,2-trichloroethyl)-phosphonate (Trichlorfon; TCP) was tested for carcinogenic activity in male and female mice derived from strain AB/Jena by oral (oesophageal-gastric intubation), intraperitoneal and dermal administration. The maximum period of treatment was 73 (oral), 73 (intraperitoneal) or 75 (dermal) weeks. During this period the following maximum mean total doses of TCP per animal had been administered: 157.5 mg(male, oral), 154 mg (female, oral), 160.8 mg (male, intraperitoneal), 149.7 mg (female, intraperitoneal). The dermally treated male and female mice had received a maximum total dose of 375 mg per animal. The study was terminated at 80 weeks. There is no statistic significant difference when compared the total tumour incidence of TCP-treated animals and control mice or the incidence of the different corresponding groups of mice separated by the route of administration or the incidence of malignant and benign tumours separated for the different groups. These findings were independent from whether the groups of TCP-treated animals and solvent control animals were combined or divided by sex for comparison.

Adenocarcinoma↗
PubMed1978

[Test of O,O-dimethyl(1-hydroxy-2,2,2-trichloroethyl)phosphonate (Trichlorfon) for carcinogenic acitivity in rats by oral (oesphageal-gastric intubation) and intraperitoneal application (author's transl)].

O,O-Dimethyl (1-hydroxy-2,2,2-trichloroethyl)phosphonate (Trichlorfon) is produced at a large scale and used in many countries e. g. in agriculture and housholds to control insects and on animals to control parasties. The compound (dissolved in isotonic sodium chloride solution) was tested for carcinogenic activity in albino rats by oral (oesophageal-gastric intubation) and intraperitoneal administration. The period of treatment was 90 weeks. The experiment was terminated at 118 weeks. There was no statistically significant difference when the tumor incidence in the groups of treated and control animals was compared. No carcinogenic activity of the compound could be demonstrated in rats at either route of application.

Administration, Oral↗
PubMed1978

[Test of 0,0-dimethyl(1-hydroxy-2,2,2-trichlorethyl)phosphonate (Trichlorfon) for carcinogenic activity in Syrian golden hamsters (Mesocricetus auratus Waterhouse) by intraperitoneal administration (author's transl)].

0,0-Dimethyl(1-hydroxy-2,2,2-trichlorethyl)phosphonate (Trichlorfon; TCP) was tested for carcinogenic activity in male and female Syrian hamsters (Mesocricetus auratus Waterhouse) by intraperitoneal administration. The period of administration was 90 weeks, when maximum total doses of 204 mg (male) and 206 mg (female) TCP per animal had been injected. The study was terminated at 100 weeks. There was no statistically significant difference, when compared the total tumour incidence, or the incidence of malignant and benign tumours separated, of the groups of treated and control animals. These findings were independent from whether the groups of TCP-injected animals and controls were combined or divided by sex.

Animals↗
PubMed1977

[The significance of in-vitro tests with respect to testing of substances for carcinogenic activities (author's transl)].

The actual possibilities to test chemical substances for carcinogenic activities are critically assessed. Short-term-tests are especially discussed. By these tests--now utilized for screening of chemicals--specific biological activities can be determined, which correlate with carcinogenic effects in vivo. The phase of checking and improving the vitro-tests is not yet finished with regard to the rate of correlation of the results from those tests and the results from long-term experiments in animals as well as from clinical and epidemiological human data. Parallel to this investigations, results from long-term-tests should be critically evaluated, because the experimental induction of tumors in animals is up to now the only way to prove carcinogenic activity of a chemical. Short-term-tests should be utilized as screening methods for the selection of suspicious substances, which should or must be further tested in long-term animal experiments. At present results from short-term-tests are not sufficient to classify a substance as a carcinogen or a non-carcinogen. Certain short-term-tests can and will get significance for the evaluation of the carcinogenic risk of chemicals to man when comparing the metabolism of carcinogens in vitro using enzymatic systems of a series of mammalians including man.

Adrenal Cortex↗