Different acute effects of oral and intratracheal administration of disodium arsenate and gallium arsenide on heme synthesis in rats

The acute influences of arsenic compounds on the metabolism of porphyrins and heme in various organs of rats after oral or intratracheal administration of disodium arsenate (Na₂HAsO₄) and gallium arsenide (GaAs) were examined and compared. For the oral administration experiments, 21 or 84 mg of Na₂HAsO₄, or 2 or 4 g of GaAs, per cm³ saline per kg body weight of each animal was administered to Jcl: Wistar male rats and the organs were removed after exsanguination from the vein of the right axilla under anesthesia with ether, 16 h after administration. In the case of intratracheal administration, rats given 8.2 or 16.4 mg of Na₂HAsO₄, or 0.2 or 0.4 g GaAs per cm³ saline per kg body weight were examined under the same experimental conditions as for the administration route. Increase in the body weight of rats was suppressed after intratracheal administration of the two arsenic compounds. In these rats the hematocrit value increased significantly. These changes were not shown by the orally administered rats. Elevation in δ-aminolevulinate synthase (ALA-S, EC 2.3.1.37) activity in erythroblasts by Na₂HAsO₄ was much higher after intratracheal administration than after oral administration. Suppression in the activities of δ-aminolevulinate dehydratase (ALA-D, EC 4.2.1.24) and porphobilinogen deaminase (PBG-D, EC 4.3.1.8) in peripheral erythrocytes by Na₂HAsO₄ and GaAs were stronger by intratracheal administration than by the oral route. Influences of GaAs on the activity of PBG-D in rat liver were shown to be more effective by oral administration than by the intratracheal route. Oral administration of Na₂HAsO₄ and GaAs had a stronger suppression effect on the activities of ALA-D and PBG-D in rat kidney. It seems from these results that the different extents of the influence of arsenic compounds might depend on the routes of intake.     

Surface-enhanced Raman scattering study of polymer on metals. III. Chemisorbed polybenzimidazole and its corrosion-inhibiting properties at high temperature

Chemisorption of polybenzimidazole on silver and copper etched with nitric acid has been observed by surface-enhanced Raman scattering (SERS). The polymer is found to react chemically with silver, forming a complexed film on the surface. The SERS spectra show that polybenzimidazole film inhibits oxidation of the metal at high temperature, unlike chemisorbed benzimidazole, benzotriazole, and poly(4-vinyl pyridine). © 1992 John Wiley & Sons, Inc.     

Mechanism of Interaction of γ-Halogenated Salts of Pyrylium and Benzopyrylium with Aromatic Amines

Stoichiometry and kinetics of reactions of 2,6-diphenyl-4-chloropyrylium, 4-chloroflavylium, 4-bromoflavylium, and 4-iodoflavylium perchlorates with nucleophiles N,N-dimethylaniline and n-phenylenediamine are studied using cyclic voltammetry and spectroscopy. Nucleophilic substitution in these compounds proceeds via the formation of a charge-transfer complex, which converts into a radical ion pair as a result of the electron transfer. Heterolytic clevage of the C–Hal bond occurs at the stage of pyranyl (flavanyl) radical.