Showing papers in "Chemico-Biological Interactions in 1993"

TL;DR: A profound similarity in structural requirements for TTR binding between hydroxy-PCB, -PCDD and -PCDF metabolites and the physiological ligand, T4 is found, e.g. halogen substitution adjacent to the para hydroxy group, while planarity does not seem to influence the ligand-binding potency.

TL;DR: A chemical hypothesis of arsenic biomethylation is developed from an examination of data and observations presented by researchers who conducted numerous in vivo and in vitro experiments and it is likely that a combination of pathways is actually used during methylation of arsenic in vivo.

TL;DR: The role of quinone methides in the synthesis of several complex plant and animal polymers, including lignin, cuticle and melanin, and the role of alkylphenols in these various processes is reviewed.

TL;DR: There is now considerable evidence that the esterase exists in two genetically determined allozymic forms, and these A and B allozymes possess both paraoxonase and arylesterase activities.

TL;DR: Human and rabbit paraoxonases/arylesterases were purified to homogeneity by chromatographic and gel electrophoretic/isofocusing procedures coupled with activity stains and it was verified that paraox onase retains its signal sequence (except for the N-terminal Met).

TL;DR: Spectroscopic evidence demonstrates that cadmium induces an oxidation of NAD(P)H in mitochondria in states 1 and 4 and prevents the reduction of mitochondrial NAD( P)+ by substrates, thus indicating that the site must be localized between NAD-linked substrates and respiratory chain.

TL;DR: It was found that the active site consists of a catalytic triad which lies close to the bottom of a deep and narrow gorge, which is lined with the rings of 14 aromatic amino acid residues, and it was suggested that the quaternary group of the choline moiety makes close contact with the indole ring of W84.

TL;DR: The cytotoxic and genotoxic properties of PAH-o-quinones suggest that DD may initiate a hitherto unrecognized pathway ofPAH activation.

TL;DR: It is hypothesized that, in OPIDN, hyperphosphorylation of cytoskeletal proteins and axonal swelling are causally linked and found of the anomalous accumulation of phosphorylated neurofilament aggregates in the central and peripheral axons of hens treated with TOCP.

TL;DR: Four mutations have been identified in resistant strains: Phe115 to Ser, Ileu199 to Val, Gly303 to Ala and Phe368 to Tyr, which led to a different pattern of resistance and combinations between these mutations led to highly resistant enzymes.

TL;DR: The purpose of this presentation is to explore similarities and differences between the esterases and to discuss possible routes for progress in the A-esterase group.

TL;DR: It is found that the H2 receptor antagonists like cimetidine, burimamide, ranitidine, famotidine and tiotidine except for being good inhibitors in histamine-stimulated gastric acid secretion, were also very powerful hydroxyl radical scavengers.

TL;DR: The protecting effect of lipoic acid was time- and pH-dependent and significant protection was seen even at 50 microM, and metal chelation with EDTA decreased the protection by lipoate, indicating that metal ions may be involved.

TL;DR: The formation and persistence of benzo[a]pyrene (BaP)- and 7H-dibenzo[c,g]-carbazole (DBC)-DNA adducts in liver of English sole and the effect of multiple doses of BaP showed that adduct levels increased linearly, suggest that hepatic xenobiotic-DNA adduction levels in English sole are molecular dosimeters of relatively longterm environmental exposure to genotoxic polycyclic aromatic compounds.

TL;DR: A wide spectrum of activities and reactivities were seen, suggesting a significant heterogeneity between the functionally similar enzymes that are present in these bacterial species, which have considerable potential for the decontamination and demilitarization of chemical warfare agents.

TL;DR: The most thoroughly studied of these enzymes is the organophosphate hydrolase (opd gene product) of Pseudomonas diminuta and Flavobacterium sp.

TL;DR: The results suggest that the enhanced potency of the MGP-PAH mixture is due to unknown interactions between the individual PAHs present in the mixture.

TL;DR: Human serum paraoxonase is responsible for the hydrolysis of organophosphate anticholinesterases, however, whether the enzyme has a physiological role other than the detoxication of insecticides and nerve gases has remained uncertain.

TL;DR: Concentrations of parent pesticide and corresponding diethylphosphorus metabolites in blood serum and urine were investigated in persons who had ingested a concentrated solution of organophosphorus pesticide chlorpyrifos and confirmed that part of chlorp Pyrifos was hydrolysed before its oxidation.

TL;DR: Dose-response studies showed maximum inducible levels for 1a-2 and 2b-10 protein, beyond which the mRNAs continued to increase while the protein levels remained constant, and an Ah receptor-independent mechanism for induction of these isozymes was suggested.

TL;DR: These products could be isolated by their hydrolysis from DNA at neutral pH, followed by chromatography of the hydrolysate in an ion-pair ODS system using a solvent containing tetrabutylammonium hydroxide as ion- Pairing reagent; this gave better separation than the previously described method using SP-Sephadex.

TL;DR: It is suggested that mercury-thiol complexes possess redox activity in biological systems, which promotes the oxidation of porphyrinogens and possibly other biomolecules.

TL;DR: It is suggested that CarbEs are more sensitive than AChE to these N-methylcarbamates and inhibition of CarbE by iso-OMPA raises the concentration of N- methyl carbamates available to inhibit A cholinesterase resulting in increased toxicity.

TL;DR: Use of acetylcholinesterase as a single pretreatment drug provided greater protection against both lethal and behavioral effects of potent organophosphates than current multicomponent drug treatments that prevent neither signs of toxicity nor behavioral deficits.

TL;DR: Tissue specific changes in the cytochrome P-450 (P-450) monooxygenase system were observed following a single subcutaneous dose of sodium arsenite, a known inducer of stress proteins, and this results are consistent with the presence of more than one form of QOR in the guinea pig.

TL;DR: The effect of various tocopherols, beta-carotene, retinol, and ascorbic acid on NO2-induced SSBs in V79 cells was investigated and none of these vitamins had any effects on DNA or the viability of cells.

TL;DR: Study of the potentiation of OPIDN may yield insight into mechanisms involved in the pathogenesis of delayed neurotoxicity and the role of NTE in both the prevention and potentiation is presented.

TL;DR: There is growing evidence for the existence of a number of enzymes which hydrolyse P-F or P-CN bonds of organophosphorous diesters e.g., the nerve gases tabun and soman, which presents further problems of classification and nomenclature.

TL;DR: Glyceryl trinitrate was denitrated in rat hepatic subcellular fractions, with formation of glyceryl dinitrates and Glyceryl mononitrates, and the cytosolic activity was shown to be dependent on glutathione and glutathion transferase and was not inhibited by dioxygen.

TL;DR: The finding that relative toxicity among a series of bromobenzene congeners is paralleled by their relative covalent binding measured in the same system in which toxicity is assessed adds support to the hypothesis that covalENT binding contributes to the observed toxicity, rather than merely being a correlated epiphenomenon.