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Biomedical subjects

K Norpoth

Publications and source records attributed to K Norpoth.

At least 73 records · Page 4Linked to original sources
PubMed1985

Determination of mutagenic activities in different fractions of automobile exhaust condensate by the Salmonella/oxygenase mutagenicity test system.

Automobile exhaust condensate of a passenger car (gasoline engine) was separated into fractions of 2-3 rings containing -, 4-7 rings containing polycyclic aromatic hydrocarbons (PAHs) and PAH-free fractions. All fractions were tested for mutagenicity by the Ames system. The highest dose-dependent increase in revertant colonies was found for the 4-7 ring PAH-fraction when tested with Salmonella typhimurium TA 98 and TA 100. These results are compatible with data obtained in in-vivo tests by previous investigations. The mutagenicity of these fractions in the absence of the oxygenase was negligible.

Animals↗
PubMed1985

[Carcinogenic agents in our environment].

Recent developments in the field of experimental toxicology might lead one to a better classification of the environmental chemicals into the groups of carcinogens and non-carcinogens. The enhanced sensitivity of the available test systems has lead us to obtain an increased number of the chemicals with low carcinogenic potencies as well as the doubtful findings that fit within no specific class. The widely discussed cancer risk of smokers and the cancer risks due to diet enhance possibilities that lead to cancer prevention, as are exampled here. In this connection, individual risk factors and the promises in risk control by the measures of Biological monitoring are emphasized.

Aflatoxins↗
PubMed1984

Non-mutagenicity of some wood-related compounds in the bacterial/microsome plate incorporation and microsuspension assays.

Seven commercially available wood-related compounds have been tested for mutagenicity by the use of the Ames and fluctuation test-systems. All compounds were found to be non-mutagenic. Among these compounds, 2,6-dimethoxy-p-benzoquinone showed a very weak and questionable mutagenic activity against Salmonella typhimurium TA 100. In this connection, probable causes of nasal adenocarcinoma of woodworkers are briefly discussed.

Animals↗
PubMed1984

Urinary excretion of frameshift mutagens in rats caused by passive smoking.

Several male Wistar rats were individually placed in a chamber resembling a room provided with minimal air flow. They were exposed separately to the main- and sidestream smoke of a commercial brand of cigarettes smoked by a smoking machine. Exposure to both sidestream and mainstream smoke of at least two cigarettes resulted in significant excretions of frameshift mutagens in urine within 24 h, detected by the bacterial microtiter fluctuation test with Salmonella typhimurium TA1538. Doubling exposure to the mainstream smoke resulted in similar quantitative mutagenic activities. Doubling exposure to the sidestream smoke resulted in reduced water intake by the animals and thus toxic effects of the urine concentrates on the test bacteria.

Air↗
PubMed1984

The influence of 18 environmentally relevant polycyclic aromatic hydrocarbons and Clophen A50, as liver monooxygenase inducers, on the mutagenic activity of benz[a]anthracene in the Ames test.

In the presence of various liver S9 preparations induced by different polycyclic aromatic hydrocarbons, the weak carcinogen, benz[a]anthracene, exhibited mutagenic activities comparable to those of benzo[a]pyrene in the Ames test. A series of positive correlations were found between mutagenic activity and the hydroxylation products of benz[a]anthracene at the 3,4-, 5,6- and 8,9-positions, of which 5,6-position was the most pronounced one (p less than 0.01). Our results suggest that the observed mutagenic activity is due mainly to the generation of K-region epoxides.

Animals↗
PubMed1983

Mutagenicity of hydrazides of pyrimidine-nucleotide-precursors in the Salmonella-oxygenase test.

Five newly synthesized hydrazides: L-aspartic acid dihydrazide, DL-ureido-succinic acid dihydrazide, DL-dihydroorotic acid hydrazide, orotic acid hydrazide, and 2,2'-anhydro-1-(beta-D-arabinofuranosyl)-orotic acid hydrazide were tested for mutagenicity in the Ames test. All these hydrazides except DL-ureidosuccinic acid dihydrazide were found to be non-mutagenic. The mutagenic activities of the latter compound which causes base-pair substitution was decreased in the presence of metabolic activator.

Animals↗
PubMed1982

[Investigations on the correlation between vinyl chloride (VCM)-uptake and excretion of its metabolites by 15 VCM-exposed workers. II. Measurements of the urinary excretion of the vcm-metabolite thiodiglycolic acid ].

Fifteen workers employed in a PVC producing plant were investigated concerning their individual vinyl chloride (VCM) exposure and the urinary excretion of the VCM metabolite thiodiglycolic acid (TdGA). The urine concentrations found were in the range 0.94-20.4 microgram/ml. These could be compared with exposure data calculated from VCM air analyses performed by personal air sampling and corrected with respect to the exposure times of the workers. The amounts of TdGA excreted within 24 h were correlated with the effective VCM body concentrations calculated from the exposure data as mean values for 12 h periods (Spearman coefficient P=alpha less than 0.005). This correlation resembles a function of the Michaelis-Menten type. It could be shown that during short exposure periods of less than 5 min, the metabolite formation in relation to the exposure data was lower than during longer periods of exposure although, as would be expected, there were some fluctuations of the exposure level. Therefore, the VCM body concentrations could not normally reach steady state values.

Environmental Exposure↗
PubMed1981

Quantitative determination of bis (chloromethyl) ether (BCME) in the ppb range by using portable air sample collectors.

Using the GC-MS technique a new method could be developed for measuring air concentrations of the carcinogenic Bis(chloromethyl)ether (BCME) at the lower ppb level after the compound has been adsorbed to Porapak Q in a sample tube. Simulation experiments have shown that the whole amount of adsorbed BCME can be recovered from the adsorbent and that the former disturbing factors (such as co-adsorbed water and thermal desorption that tended to decompose the BCME and thus falsify the results of analyses) are wholly eliminated. The storage time of BCME in the tube has no influence on the recovery rate.

Air Pollutants↗
PubMed1981

Malignant tumors after chronic exposure to vinyl chloride.

Correlations between exposure to vinyl chloride and the development of malignant tumors in the liver have been know since 1974 and have been confirmed by many an experimental investigation. Based on the evaluation of mortality statistics from nine different countries an increased incidence of malignant tumors of the lung, the gastrointestinal tract, and the central nervous system (CNS), and of malignant lymphomas is documented in connection with exposure to vinyl chloride. Statistically significant increases, however, are only found in the incidence of malignant liver tumors. Metabolism and toxicology of vinyl chloride are discussed in detail.

Animals↗
PubMed1980

The detection of mutagenic air pollutants from filter samples by the Salmonella/Mammalian S-9 mutagenicity test (Ames test) with S. typhimurium TA 98 (Part 1).

Particulate airborne pollutants, collected in 1977 at an urban point in Wanne-Eickel, G.F.R., were investigated for mutagenic activity in the Ames Salmonella/mammalian S-9 mutagenicity tet with S. typhimurium TA98. Two kinds of filters were used: Mikrosorbanfilters (polystyrene) and Membranfilters (cellulose nitrate). Sample preparations obtained following gel chromatography of solutions of the Mikrosorbanfilters showed only weak mutagenic activity. Soxhlet extracts of the Membranfilters gave positive dose-response relations (figs. 3-6), while splitting the initial extract into six fractions resulted in the bacterial reversion rates due to certain sub-fractions increasing over the reversion rates due to the unfractionated preparation (fig. 7). The highest activities were observed in the fractions of the polar compounds and of the polycyclic aromatic hydrocarbons. Some (30-50%) of the mutagenic activity was not enzymatically mediated. GC-MS analysis of the samples demonstrated the presence of an average content of around 11 microgram benzo(a)-pyrene/1000 m3 of air.

Air↗
PubMed1980

Spectral evidence of interaction of spice constituents with hepatic microsomal cytochrome P-450.

Spectral evidence has been obtained of the interaction of constituents of two commonly used spices, capsicum and cinnamon, with hepatic microsomal cytochrome P-450. It is proposed that influences of spice constituents on hepatic mixed-function oxidase activities may merit consideration during the investigation of some health-related problems characteristic of, or peculiar to, a given region or cultural group. An example considered relates to the evaluation of certain 'traditional medicines'.

Capsicum↗