Showing papers in "Chemico-Biological Interactions in 1976"

TL;DR: The results indicate a mechanism for the initiation and promotion of peroxidative attacks on membrane lipids and suggest that the role of antioxidants in intracellular metabolism may be to inhibit initiation of degradative reactions by the highly reactive radicals formed extraneously during metabolic activity.

TL;DR: The structural analysis of the persistently bound form of the carcinogen N-acetyl-2-aminofluorene to rat liver DNA in vivo is described, which appears to result from the formation of a covalent bond between carbon-3 of the aromatic ring and the amino group of guanine.

TL;DR: Accumulation of cadmium was associated with an increased zinc concentration in the liver and an increased copper concentration inThe kidney; these increases were correlated with increases in liver and kidney metallothioneins induced by cad mium.

TL;DR: Chloroethylene oxide was found to be approximately 450 times more effective as a mutagen than chloroacetaldehyde when the comparison is based on exposure doses, defined as the time-dependent concentrations of the compounds in the treatment solutions, integrated between the times of onset and termination of treatment.

TL;DR: 62 pyrrolizidine alkaloids and derivatives have been screened for acute and chronic hepato- and pneumotoxicity by the single dose method, with new findings significant in relation to hepatotoxicity.

TL;DR: Amino acid incorporation studies revealed that active biosynthesis of metallothionein took place in the kidney as well as in the liver of cadmium-exposed rats.

TL;DR: It is demonstrated that Cu(I) is more toxic than Cu(II) to cells when applied under anoxic conditions and that colonies on plates are largely anoxic even when incubated aerobically.

TL;DR: Exposure of rats to elemental mercury vapor results in increased amounts of a metallothionein-like protein in kidney tissue but not in liver, and a significant incorporation of [U-14C]-cystine into this protein in rat kidney alone on exposure to mercury vapor confirms its induced biosynthesis in the kidney.

TL;DR: The H202 generating capacity of mitomycin-DNA complexes inside the nucleus may play a role in the drug-induced biological damage to the genetic material of cells.

TL;DR: It is suggested that methylations of adenine or guanine in DNA at N-3 constitute blocks to template activity of DNA and stimulate a "repair" response of enzymatic removal of 3-methylpurines.

TL;DR: Differential growth inhibition of two E. coli cultures was evaluated as a rapid screening technique for chemical carcinogens, and only "direct acting" carcinogens produced positive results.

TL;DR: In general, enzyme activity was strongly reduced by heavy metal inorganic cations; less strongly by organometallic cations, some anions, and certain pesticides; and weakly inhibited by light metal cations and Organometallic and organic compounds.

TL;DR: Preliminary data linking this phenotypic lag to the slow degradation rate of hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and to an apparent requirement for very low cellular HGPRT content in order for cells to be resistant to 10 mug 6TG/ml are presented.

TL;DR: The degradation in alkali of normal DNA and DNA alkylated with dimethyl sulphate (DMS), N-methyl-N-nitrosourea (MNUA) and N-ethyl-N -nitrosOUrea (ENUA) has been investigated using analytical ultracentrifugation techniques.

TL;DR: Preliminary studies in vitro using bacteriophage T7-DNA have shown that breaks formed in the DNA on the alkaline hydrolysis of apurinic sites and phosphotriesters can be distinguished from each other by measuring the extent of degradation of the DNA immediately after adding NaOH to 0.1 M and after incubating for 1 h in 0.5 M NaOH.

TL;DR: Administration of 3-methylcholanthrene to rats greatly enhanced the aryl hydrocarbon hydroxylase (AHH) activity of liver nuclei, but the binding in vitro [3H]benzo[alpha]pyrene (BP) to DNA within the nuclei which occurred at the same time ashydroxylation of BP was much less enhanced.

TL;DR: It is shown that the three pure hexachlorobiphenyl isomers initially produce changes in hepatic microsomal activity which resemble those seen after treatment with phenobarbitone (PB), and a relationship may exist between the mixed pattern of enzyme induction and the onset of hepatic porphyrin accumulation.

TL;DR: It is proposed that inhibition of this post-replicative DNA repair process provides a molecular basis for the previously observed potentiation by caffeine of cis Pt(II)-induced chromosomal aberrations and lethality.

TL;DR: Treatment of Syrian hamster embryo cells with diverse classes of chemical carcinogens enhanced transformation by a carcinogenic simian adenovirus, SA7, and chemicals that cause DNA damage, which can be repaired by hamster cells, may enhance viral transformation by providing additional sites for integration of viral DNA during the repair process.

TL;DR: It is concluded that binding of Hg2+ by pre-induced cadmium-thionein alone cannot explain the protection by Cd2+ against the nephrotoxicity of HG2+.

TL;DR: The glutathione concentration in the livers of the retrorsine-dosed rats is higher than those of the corresponding controls and there was no significant change in the liver weights of the treated rats relative to the controls.

TL;DR: It is shown that PR toxin inhibits both initiation and elongation of the polynucleotide chain in the transcription process affected, and in vitro results suggest thatPR toxin impairs the activity of the RNA polymerase itself.

TL;DR: The formation of tris(GS)-DMAP in red cells was found to be of importance for the termination of catalytic ferrihemoglobin formation by DMAP in vivo, and reduced glutathione in high concentrations substantially diminished binding of oxidized DMAP to hemoglobin.

TL;DR: While both phenobarbital and MC powerfully repress the DMN-demethylase, it is confirmed that they are strong inducers of the synthesis of P-450 and P-448, respectively, as estimated from the difference spectra.

TL;DR: Equinatoxin, a highly basic protein extracted from Actinia equina, causes an increase in the survival time of mice bearing the ascitic form of Ehrlich carcinoma, whereas it has no effect on L1210 leukaemia, suggesting its mechanism of action may be related to interactions with lipids or other charged components of cell membrane.

TL;DR: It was shown that the carcinogen binds preferentially to the regions of chromatin sensitive to the enzyme; however, the areas of DNA tightly bound to histones and resistant to the enzymes react comparatively well.

TL;DR: Thymidine kinase activity and DNA polymerase activity were enhanced in the lungs of BHT-treated animals and maximum activity of these enzymes appeared to precede maximum thymidine incorporation by 24 h.

TL;DR: The kinetics of benzypyrene (BP) metabolism were examined in liver microsomes, and in accordance with the results of Hansen and Fouts, curcilinear Lineweaver-Burk plots were exhibited.

TL;DR: In vivo experiments using 203Pb and radioactively labelled precursors such as [14C] arginine and [3H] tryptophan were performed to identify lead binding components in rat liver, showing that lead was almost exclusively bound to membranes of rough-surfaced microsomes associated with the heavy rough membrane subfraction.