Many small alkyl and vinyl halides are used on a large scale in industrial settings, and most are potentially capable of causing cancer. In general these compounds cause mutations, after activation by various metabolic pathways. In many cases oxidation by cytochrome P450 enzymes results in the formation of electrophiles that bind DNA ; however, sometimes activation is the result of enzymatic conjugation with glutathione (GSH). The adducts derived from vinyl chloride (via 2-chlorooxirane) are best characterized and include N⁷-(2-oxoethyl) guanine, 1, N⁶-etheno (ε) adenine, 5, 6, 7, 9-tetrahydro-7-hydroxy-9-oxoimidazo [1, 2-a] purine, 3, N⁴-ε-cytosine, N², 3-ε-guanine, and 1, N²-ε-guanine. All of the ε adducts are capable of miscoding in various situations, and the extent of misincorporation seems to vary with the polymerase. Monoalkyl halides react directly with DNA, and evidence exists for the importance of O⁶-alkyl guanines and O²- and O⁴-alkyl thymidines in miscoding. Several of the vinyl and alkyl halides can be activated to electrophiles by enzymatic GSH conjugation. This group includes polyhalogenated olefins, which appear to yield N-acyl-modified DNA adducts and their derivatives. GSH conjugation with 1, 2-dihaloalkanes yields half-mustards, which form episulfonium ions due to anchimeric assistance. Known DNA adducts derived from 1, 2-dibromoethane include S-[2-(N⁷-guanyl) ethyl] GSH, S-[2-(N¹-adenyl) ethyl] GSH, S-[2-(N²-guanyl) ethyl] GSH, and S-[2-(O⁶-guanyl) ethyl] GSH. One of the guanyl adducts appears to be responsible for the GC to AT transitions observed in several different systems. The activation of dihalomethanes (e.g. CH₂Cl₂) is also understood in terms of GSH conjugation, which yields S-[1-(N²-guanyl) methyl] GSH. This type of activation scheme may also apply with CHCl₃.

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The absorption spectra, ethidium bromide fluorescent spectra and circular dichroism (CD) spectra indicate that six β-carboline derivatives, norharman, harman, harmol, harmine, harmalol and harmaline intercalate into DNA. This result is supported by unwinding experiments using the superhelical plasmid pBR322 DNA, and the magnitude of intercalation except for harmalol decreased in the order of harmol>harmine>harmaline>harman>norharman. The potency of the interactions was further determined by spectrophotometric titration. The Scatchard plots were then analyzed using the Langmuir equation including two terms for specific and non-specific interactions. The interaction of the β-carboline derivatives with DNA is characterized as follows : 1) Substitution into the β-carboline skeleton rings decreases the number of binding sites. 2) The polar groups OH and OCH₃ increase the binding affinity at the first specific term. 3) A decrease in the planarity of the β-carboline skeleton decreases the binding affinity. 4) The interaction of harmalol with DNA may be less potent than that of harmine.

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The preventive effects of the extract (DP-extract) prepared from leaves of Eucommia ulmoides OLIVER, Eucommiaceae (Du-Zhong leaf) and roots of Panax ginseng C.A. MEYER (Ginseng), which are widely used as healthful teas, on acute toxicity of chlorpyrifos, a common organophosphorus insecticide, were investigated in mice. A 50% lethal dose of chlorpyrifos was 16.9% higher in the group pretreated with DP-extract for 3 weeks (6.66 g of dried leaves and root/kg/d, p.o.) than in the chlorpyrifos alone group. Cholinesterase (ChE) activities in serum were higher and the residual chlorpyrifos in liver was lower in mice pretreated with DP-extract than in the chlorpyrifos-alone group. Hepatic cytochrome P450 content, activities of NADPH-cytochrome c reductase and carboxylesterase (EC3.1.1.1) in livers of DP-extract pretreated mice were significantly higher than those of untreated control immediately after chlorpyrifos injection. The activities of those enzymes were also significantly higher in the DP-extract pretreated mice than the controls. Northern blot analysis of microsomes from livers of DP-extract pretreated mice revealed the increased transcription of NADPH-cytochrome c reductase and carboxylesterase. These results suggest that DP-extract increased the activities of cytochrome P450 and carboxylesterase and accelerated detoxification of chlorpyrifos to prevent the acute toxicity of the organophosphorus insecticide.

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We have already reported the effect of ultraviolet-A (UVA)-sensitization of hematoporphyrin (HP) on the production of lipid hydroperoxides in erythrocytes and on their hemolysis. In this report, we investigated these effects under ultraviolet-B (UVB) irradiation and compared the results with those under UVA irradiation. It was found that an increase in lipid hydroperoxide preceded hemolysis, and that the UVB irradiation resulted in an increase in phosphatidylethanolamine hydroperoxide (PEOOH) and 2-thiobarbituric acid reactive substances (TBA-RS) at an earlier stage in comparison with UVA irradiation. Under either UVA or UVB irradiation, hemolysis was inhibited by anti-oxidants such as sodium azide and ascorbic acid (singlet oxygen scavengers), but not by mannitol, sorbitol (hydroxyl radical scavengers) or superoxide disumutase (SOD) (superoxide radical scavenger). These results suggest that singlet oxygen (¹O₂) produced by UV irradiation peroxidized the lipids of erythrocyte membranes, and therefore, the hemolysis of erythrocytes occured when the amount of hydroperoxides increased to a constant level, but auto-oxidation of lipids did not affect the hemolysis.

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The analytical procedure and detectable period of a muscular relaxant, suxamethonium, in postmortem rat tissues were studied. Rats were killed by intraperitoneal administration of suxamethonium at doses of 10 mg/kg body weight. The dead rats were stored at room temperature (25°C) and in refrigerator (0°C) until the time of the analysis. Suxamethonium in the tissues was identified and quantitated using Frit-FAB LC-MS following the solid phase extraction with a Bond Elut CBA cartridge. The rat tissue was homogenized and deproteinized with perchloric acid. The resulting supernatant was applied to the cartridge. Suxamethonium adsorbed on the cartridge was eluted with 1 ml of 0.1 M hydrochloride-methanol (1 : 1, v/v). Hexamethonium solution was added to the eluate as an internal standard. An aliquot (1 μl) of the eluate was injected into the Frit-FAB LC-MS system. The LC column used was a capillary-type Develosil ODS-UG-5 (0.3 mm i.d.×150 mm). The gradient mobile phase system was composed of eluent A (0.1% trifluoroacetic acid, including 0.4% glycerol) and eluent B (methanol, including 0.4% glycerol), and the concentration of eluent B increased from 0% to 30% over 20 min. The flow rate was 5 μl/min. The mass spectrum of suxamethonium gave the adduct of a molecular ion with trifluoroacetic acid (m/z 403) as a base peak. The detection limit of suxamethonium in the tissue by selected ion monitoring (SIM) was 5 ng/g. Suxamethonium in rats stored at 25°C and 0°C after death were found to be detectable for 7 and 42 d in the liver, 7 and 42 d in the kidney, and 2 and 4 d in the heart, respectively.

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The experimental studies on the improvement of electrode materials used for the electrolytic enrichment of tritium and on the establishment of rapid procedure for the analysis of tritium and its application to tritium monitoring in environmental surface water at south Osaka area were carried out. The more efficient recovery rate and reappearance of tritium were obtained by the trial of the exchange of the electrode material from nickel (Ni) to iron (Fe) at high current condition. However, by considering the electrolytic corrosiveness of iron, a combined multi plate electrode of Fe (-)-Ni (+) (an effective surface area ; 63cm²) was adopted. In the case of such operational conditions that a current density ; 180 mA/cm² and a cooling temperature ; 5°C using a 100 ml glass cell inserted into the electrode, time required for decreasing the volume of sample solution from 100 ml to 15 ml was more than 22 h. In addition the recovery rate and the concentration ratio of tritium were 90% and 6 times respectively. Then, the tritium activity of the water sample could be counted rapidly with a relative counting error of ±20% for 4 h in a low level liquid scintillation counter. By the trial using the above mentioned method for the tritium monitoring in environmental surface water at south Osaka area from 1986 to 1992, it was proved that the tritium activities decreased to the naturally producing level of tritium (BG) during this term and the decreasing half times of tritium concentration in this area by dilution were about 4 years.

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Total inhalation deposition of direct-acting mutagenicity associated with environmental tobacco smoke (ETS) aerosol was measured in a human volunteer. The exposures were conducted in a normal office containing well circulated ETS. The ETS aerosol was collected by filtration in the exhaled air using the Hans Rudolph mask connected to a filter holder and respirometer. The inhaled indoor air was collected by low volume air sampler. The direct-acting mutagenicity of the aerosol was determined using the ultramicrosuspension forward mutation assay in Salmonella typhimurium strain TM677. The deposition ratio was estimated as ca. 55% from the difference of the mutagenicity between exhaled and inhaled air.

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Ester types (2, 4-dichlorophenoxyacetic acid (2, 4-D) ethyl, 2, 4-D butyl and MCPA-thioethyl) and free acid types (2, 4-D, 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T), 2-methyl-4-chlorophenoxyacetic acid (MCPA), m-chloroperbenzoic acid (MCPB), mecoprop and dichlorprop) of phenoxy acid herbicides in agricultural products were simultaneously extracted from samples with acetone for vegetables/fruits, and with acetonitrile for cereals/beans, and then re-extracted with ethyl acetate. Three ester types of herbicides extracted from the samples were cleaned up by Sep-Pak^[○!R] Florisil, and then determined by ECD-GC and GC-MS (SIM). Recoveries of the ester types of herbicides determined by GC and GC-MS spiked at 1.25 ppm to asparagus, taro, brown rice and corn were 61.4-76.9% and 50.8-63.9%, respectively. Six free acid types of herbicides were esterified by pentafluorobenzyl bromide or diazomethane and determined by GC-MS (SIM) without cleaning up by solid phase extraction. Recoveries of the free acid types of herbicides esterified by pentafluorobenzylation and methylation spiked at 1.25 ppm to the samples were 68.5-98.5% and 53.7-88.1%, respectively. It was clarified that the concentration of pentafluorobenzyl bromide in acetone should be 5-10% to have sufficient recoveries for the esterification. Methylation was superior to pentafluorobenzylation for the simplicity of manipulation, but was inferior for the sensitivity of GC and GC-MS.

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The disinfecting effects of an ultra sonic ozone washer were evaluated in antiseptic-resistant strains of methicillin-resistant Staphylococcus aureus (MRSA). Two antiseptic-sensitive strains and two antiseptic-resistant strains were killed after treatment with the washer. (The leakage of the ozone gas from the washer was not detected.) The resin-plates to which gingival bacteria, Candida albicans and gingivalis bacteria, Streptococcus sanguis, adhered, were used as a model for the washing of an artificial tooth. The numbers of these bacteria detected before the washing, were both 10⁷ cfu/ml while those detected in washing water before washing with ozonized water were respectively none and 10⁴ cfu/ml. Only 10-20 colonies were grown on the resin-plates of both bacteria. A resin-plate adhering Helicobacter pylori, which is presumed to be associated with active chronic gastritis and duodenal ulcer diseases, was also tested. Bacteria of 10⁸ cfu/ml before the washing was not detected in washing water after washing with ozonized water. Only 10-20 colonies were grown on the resin-plate. These results clearly confirmed that the ultra sonic ozone washer are a useful means for disinfecting instruments and devices contaminated with antisepticresistant strains of MRSA and an artificial tooth.

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