PubMed · 4435421
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
P P Dikun. 1974. [Possible principles for setting standards for carcinogenic substances].. https://pubmed.ncbi.nlm.nih.gov/4435421/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
This paper presented a framework for analysis of chemical concentration in the environment and evaluation of variance propagation within the model. This framework was illustrated through a case study of selected organic compounds of benzo[alpha]pyrene (BAP) and hexachlorobenzene (HCB) in the Great Lakes region. A multimedia environmental fate model was applied to perform stochastic simulations of chemical concentrations in various media. Both uncertainty in chemical properties and variability in hydrometeorological parameters were included in the Monte Carlo simulation, resulting in a distribution of concentrations in each medium. Parameters of compartmental dimensions, densities, emissions, and background concentrations were assumed to be constant in this study. The predicted concentrations in air, surface water and sediment were compared to reported data for validation purpose. Based on rank correlations, a sensitivity analysis was conducted to determine the influence of individual input parameters on the output variance for concentration in each environmental medium and for the basin-wide total mass inventory. Results of model validation indicated that the model predictions were in reasonable agreement with spatial distribution patterns, among the five lake basins, of reported data in the literature. For the chemical and environmental parameters given in this study, parameters associated to air-ground partitioning (such as moisture in surface soil, vapor pressure, and deposition velocity) and chemical distribution in soil solid (such as organic carbon partition coefficient and organic carbon content in root-zone soil) were targeted to reduce the uncertainty in basin-wide mass inventory. This results of sensitivity analysis in this study also indicated that the model sensitivity to an input parameter might be affected by the magnitudes of input parameters defined by the parameter settings in the simulation scenario. Therefore, uncertainty and sensitivity analyses for environmental fate models was suggested to be conducted after the model output was validated based on an appropriate input parameter settings.
Benzo[a]pyrene (BP) is a widely distributed environmental pollutant that is metabolized by mammalian cells to a variety of genotoxic and carcinogenic intermediates that form covalent adducts with cellular DNA. One such pathway involves the metabolic activation of BP by members of the aldo-keto-reductase (AKR) family of enzymes to the highly reactive ortho-quinone, benzo[a]pyrene-7,8-dione (BPQ). This compound has been reported to react with the 2'-deoxynucleosides, dA and dG, under physiological conditions. Four BPQ-dG adducts and two -dA adducts were identified by mass spectrometry and NMR methods [Balu et al. (2004) Chem. Res. Toxicol. 17, 827-838]. However, the detailed conformations and absolute configurations around the linkage site have not been resolved. In order to determine the full conformations of these purine adducts, we carried out quantum mechanical geometry optimization using density functional theory. In the case of the BPQ-guanine adducts, six possible structures, each of which consists of two isomers, were identified. However, in the case of the adenine adducts, only four isomers were identified. The results suggest that stereoisomeric adduct pairs are expected to adopt opposite orientations with respect to the 5'-->3' direction of the modified DNA strands. The stereochemistry-dependent variations in adduct orientation may produce different biological effects, as has been observed in the case of DNA adducts derived from other metabolites of polycyclic aromatic hydrocarbons.
With the [Re(CO)(3)Br(3)](2-) ion as a precursor for the Re(I)(CO)(3) fragment, the diols (1R,2R)-cyclohexane-1,2-diol [(1R,2R)-Chxd], anhydroerythritol (AnEryt), and (1S,2S)-cyclopentane-1,2-diol [(1S,2S)-Cptd] form dinuclear monoanions in the salts (NBu(4))[(Re(2)(CO)(6){mu-(1R,2R)-ChxdH(-1)}(3)] (1), [K([18]crown-6)][Re(2)(CO)(6)(mu-OMe)(2)(mu-AnErytH(-1))] (2) and (NBu(4))[Re(2)(CO)(6){mu-(1S,2S)-CptdH(-1)}(3)] (3). The monoanionic diolato ligands in these triply bridged dirhenates(I) are monodentate. Bridging triolato ligation in the trirhenates(I) is supported by the anions of glycerol (Glyc) and methyl beta-D-ribopyranoside (Me-beta-D-Ribp), the latter binding in its (1)C(4) conformation, in (DBUH)(2)[Re(3)(CO)(9)(mu(3)-O)(mu(3)-GlycH(-3))]0.5 MeCN (4 a), (NEt(4))[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-GlycH(-3))] (4 b) and (DBUH)[Re(3)(CO)(9)(mu(3)-OMe)(mu(3)-(1)C(4)-Me-beta-D-Ribp2,3,4H(-3))] (5). The chiral sugar alcohols L-threitol (L-Thre) and D-arabitol (D-Arab) act as tetra- and pentadentate ligands, respectively, in (NEt(4))[Re(2)(CO)(6)(L-ThreH(-3))]MeCN (6) and (NEt(4))(2)(DBUH)(2)[Re(6)(CO)(18)(D-ArabH(-5))(2)] (7). Complexes 6 and 7 are free of supporting oxo or methoxo ligands and use solely the O-atom pattern of the polyol for the connection of the Re(I)(CO)(3) moieties.