Showing papers in "Chemico-Biological Interactions in 1991"

TL;DR: The higher redox potential benzoquinones and naphthoquinones are the most cytotoxic presumably because of their higher electrophilicty and thiol reactivity and/or because the quinones or GSH conjugates are more readily reduced to semiquinones which activate oxygen.

TL;DR: A comprehensive hypothesis is presented that focuses on the extracellular generation of reactive oxygen in the hepatic sinusoids, where Kupffer cell-derived reactive oxygen species seem to be involved in the initial vascular and parenchymal cell injury and indirectly also in the recruitment of neutrophils into the liver.

TL;DR: There is evidence emerging that release of Ca2+ from mitochondria may be physiologically important for cell proliferation and differentiation.

TL;DR: In in vitro experiments, using rat hepatocytes, the cytochrome P-450IA1 apoprotein level, 7-ethoxyresorufin O-deethylation activity (EROD) and DT-diaphorase activity (DTD) were markedly enhanced by DIM and CTI as well as BII.

TL;DR: The observation that carotenoids can inhibit neoplastic cell transformation when administered not only together with but also after the application of chemical or physical carcinogens might indicate a role of singlet oxygen in tumor promotion that could be independent of the direct or indirect DNA damaging properties.

TL;DR: Experimental evidence supporting a crucial role of thiol oxidation and elevation of cytoplasmic calcium concentration in bleb formation is provided and demonstrates that cytoskeletal structures and the microfilament system in particular, represent important targets in menadione-induced morphological changes in cultured cells.

TL;DR: The aim of this review is to summarize the current knowledge on the biosynthesis and toxicity of glutathione S-conjugates derived from halogenated alkanes, halogensated alkenes, and hydroquinones and quinones.

TL;DR: The results show that oral GSH can increase GSH concentrations in several tissues following GSH depletion, such as can occur in toxicological and pathological conditions in which GSH homeostasis is compromised.

TL;DR: It is hypothesized that BHA gives rise to tumor formation in rodent forestomach by inducing heritable changes in DNA, and evidence is being provided that reactive oxygen species, in particular hydroxylradicals, may play a crucial role.

TL;DR: Evidence is presented which supports a role for PHS in the bioactivation of several polycyclic aromatic hydrocarbons and aromatic amines, two classes of carcinogens which induce extrahepatic neoplasia.

TL;DR: It is suggested that the antioxidant action of captopril in vivo is likely to be limited, and may be restricted to protection against damage by hypochlorous acid derived from the action of neutrophil myeloperoxidase.

TL;DR: Eugenol is actively metabolized in hepatocytes and the cytotoxic effects of eugenol are suggested to be due to the formation of a reactive intermediate, possibly a quinone methide.

TL;DR: Superoxide dismutase (SOD) did not abolish the induction period but dramatically enhanced the autoxidation rate by more than two orders of magnitude, thus explaining the saturation effects of SOD.

TL;DR: It is demonstrated that organophosphates and organoph phosphites are relatively effective inhibitors of human monocyte CBE activity with the exception of the alkylphosphates which have no inhibitory activity.

TL;DR: The protective effect of the broccoli diet on chemically induced tumors in rodents may be caused by the broccoli-induced changes in P450IA and IIB associated enzyme activities.

TL;DR: The results show that vesiculation is a common phenomenon induced by amphiphiles in erythrocytes, and it is suggested that a rapid efflux of ions decreases the difference in osmotic pressure between cell interior and hypotonic buffer, thereby protecting cells from being lysed.

TL;DR: In the cells exposed to highly toxic metals such as cadmium and mercury, expression of cytotoxicity was remarkable at the metal concentrations higher than those saturating thionein induction, supporting the protective role of MTs against heavy metals.

TL;DR: The data of this paper are in favor of the conclusion that some lignans, like Sal, have strong anti-oxidant activity.

TL;DR: The metabolically inert PP, perfluorooctanoic acid, was found to act as a promoter of liver tumors in the rat induced by diethylnitrosamine in an initiation-selection-promotion protocol.

TL;DR: The Hb adducts proved to be stable and are therefore useful for dosimetry of long-term exposure to butadiene and are compatible with a linear dose response up to 1000 ppm.

TL;DR: These studies show that dietary BaP, and metabolites likely to be present in invertebrates, can be absorbed by the southern flounder and form DNA adducts in target organs.

TL;DR: The presence of Fe(II)-DTPA complex in the reaction medium led to a reduction in the amount of adenine N-1-oxide by a factor of 4 whereas radical DNA type damages including 8-hydroxyguanine and 5-hydroxymethyluracil was increased by a factors of 2-3.

TL;DR: The antioxidant capacity of thyroid hormones found in vitro may not be of relevance in physiological conditions, which exhibit variations of T3 and T4 levels in the nanomolar range, while the behaviour of propylthiouracil as an inhibitor of EPM lipid peroxidation is observed at concentrations close to the therapeutic levels, thus representing a possible complementary action to its antithyroid activity.

TL;DR: Juvenile English sole exposed intramuscularly to nitrofurantoin and the levels of 8-hydroxy-2' deoxyguanosine (8-OH-dG) in liver, kidney and blood were determined using reversed-phase HPLC with electrochemical detection demonstrate the first direct evidence for the formation of oxidized DNA bases resulting from the metabolism of a nitroaromatic compound by fish.

TL;DR: A direct comparison of propylene oxide with the homologous compound ethylene oxide on the basis of adduct levels introduced (in DNA and in hemoglobin) at equimolar injected amounts, shows that Propylene oxide is 6-10 times less effective than ethyleneoxide.

TL;DR: The potent mutagenicity of the fjord region diol-epoxides appears to be due to the high frequency with which they form DNA adducts in V79 cells, rather than to formation ofAdducts with greater mutagenic potential.

TL;DR: The highly efficient metabolic activation of dichlobenil to reactive intermediates in the olfactory mucosa is suggested to be of importance for the potent dichlOBenil-induced toxicity in this tissue.

TL;DR: It is proposed that DHAA by intercalating into the lipid bilayer of the membrane, affects the dynamics of the bilayer which in turn alters the permeability of the Bilayer and the function of ion transporting membrane proteins.

TL;DR: The results suggest that iron chelated to DNA may be significant in DNA damage induced by oxidizable chemicals.

TL;DR: The results suggest that large N-7-dGMP adducts are very poor substrates of T4 polynucleotide kinase, indicating stereoselectivity in the kinase reaction.