Showing papers in "Chemico-Biological Interactions in 1972"

TL;DR: A class of compounds have been found which are some thirty to forty times more active against the plasma cell tumour than the platinum complex at present on clinical trial.

TL;DR: Relationships can be demonstrated between the acute hepatotoxicity of some pyrrolizidine alkaloids and the amounts of pyrrolic metabolites found in livers of rats given the alkaloid, suggesting that toxic effects are caused by such metabolites.

TL;DR: A spot test with selected repair-deficient strains of Escherichia coli is described which not only provides a sensitive assay for the mutagenic activity of chemicals, but also gives useful information about the characteristics of the Mutagenic process.

TL;DR: A single dose of 2 mg of N -methyl- N -nitrosourea was instilled directly into the urinary bladder of each of 50 male Wistar rats, but despite initial epithelial necrosis followed by hyperplasia none of these developed tumours.

TL;DR: Drugs containing one or two allyl substituents were found to depress the activity of catalase and the levels of cytochrome P-450; they were also porphyrogenic.

TL;DR: Studying of the kinetics of the binding of the Pt compounds to bacteriophage suggest that aggregation or polymerisation of the compounds may be reactions competing with the binding process.

TL;DR: The in vivo administration of piperonyl butoxide or propyl isome to mice affects the levels of several hepatic cytochrome P-450 spectral interactions, and the ethyl isocyanide (EtNC) equilibrium point undergoes a biphasic shift.

TL;DR: An assay for quantitating repair replication in HeLa cells was utilized which employed hydroxyurea (HU) for the purpose of selectively suppressing normal, semi-conservative replication, and none of the compounds tested exerted a marked inhibitory effect upon repair synthesis in UV-irradiated cells.

TL;DR: In hamster embryonic cells that undergo malignant transformation, the epoxide of benz[a]anthracene was bound to all macromolecules to a much greater extent than the hydrocarbon and other derivatives.

TL;DR: Although it remains to be shown whether DNA methylation is related to the initiation of cancer, the data presented are consistent with the hypothesis that cytoplasmic mutations are involved in carcinogenesis.

TL;DR: It is suggested that DDE is a more potent inducer of microsomal protein, cytochrome P-450 and aniline hydroxylase in both species, than DDT fed at the same level, and the effects of DDT were best expressed in terms of the resulting DDE residue levels.

TL;DR: From these results, it is clear that the mode of action of the 1,8-naphthalic anhydride is not that of a simple interference in the uptake or metabolism of EPTC but indicates that a more subtle or complicated process is involved.

TL;DR: Subcutaneous administrations of methylmercury hydroxide to male rats markedly reduced the content of microsomal cytochromes P-450 and b 5, and depression of aminopyrine demethylase on a per gram liver basis occurred primarily in the SER.

TL;DR: A comparison of difference spectra formed with microsomal cytochrome P-450 from a susceptible and a resistant strain of house flies shows both quantitative and qualitative differences, similar to those observed for the same spectra between normal and phenobarbital- or 3-methylcholanthrene-treated mammals.

TL;DR: The extremely low solubility of benzpyrene in aqueous solutions, together with the propensity of this polycyclic hydrocarbon to bind to non-hydroxylating sites on proteins, suggested that the kinetics of substrate availability might significantly contribute to the observed non-Michaelis-Menten kinetics.

TL;DR: An isopycnic gradient technique is described by which interstrand cross-linking of DNA in mammalian cells resulting from treatment with difunctional alkylating agents can be quantitated.

TL;DR: Correlations were studied between the inhibitory effect and certain physicochemical properties of chemicals, the best being found between the inhibition of GOT and the equilibrium constants of metal sulfides.

TL;DR: Cloned cell lines established from Yoshida ascites tumour lines known to be sensitive and resistant to methylene dimethanesulphonate in vivo show similar sensitivities to methyl methanesulponate (MMS) and X-rays.

TL;DR: According to gel-filtration experiments, radioactivity is bound to plasma proteins, predominantly albumin, to a comparable degree a few hours after administration of all three compounds, which implies that binding sites are not saturated and reactive metabolites are not increased in the blood during 6 weeks of feeding low, but carcinogenic doses of trans-DAS.

TL;DR: The binding of [3H]urethane to liver DNA and RNA has been examined in partially hepatectomised and intact male Crackenbush mice and neither the restoration of liver mass nor an alteration in the metabolism of urethane appeared to account for the different levels of binding.

TL;DR: Failure of efficient protection of DNA by nucleic acid constituents against bisulfite action further suggests that the DNA molecule is a far more sensitive target than mononucleotides or the RNA molecule.

TL;DR: The ability of Pb2+ depolymerized tRNA to bind to ribosomes in response to its appropriate codon is impaired to a greater extent than the ability of the t RNA to accept amino acids.

TL;DR: It appears that there is a structural requirement in the coenzyme Q family for stimulation of phagocytosis in rats for a quinoidal moiety with an at least partially unsaturated side chain.

TL;DR: Spectral interactions of various cannabinoids with rat liver microsomes were studied and it was suggested that the lack of inhibitory effect on Δ 1 -THC hydroxylation by hexobarbital may be ascribed to substantial differences in binding affinity for cytochrome P-450 by the two substances.

TL;DR: It is concluded that the liver-N-demethylating enzyme activity governs (a) the rate of methylation of liver DNA, and (b) the amount of systemic DMNA available for metabolic demethylation and DNA methylation in lung and kidney.

TL;DR: In this paper, a single intraperitoneal dose of dimethylnitrosamine (DMNA) (30 mg/kg) to rats produces centrilobular hepatocellular necrosis within 18-24h.

TL;DR: In the reconstituted liver microsomal hydroxylation system, the rate of pentobarbital oxidation is greater in the presence of cytochrome P-450 than in the present day, which may explain the inhibitory effect of 3-methylcholanthrene on pentobarBital metabolism in vivo.