Neopterin is an α-amino-hydroxypteridine derivative, and a precursor of biopterin, which is derived from guanosine triphosphate. As for biological roles of pteridines, 5, 6, 7, 8-tetrahydrobiopterin serves as a cofactor for mammalian aromatic amino acid monooxygenases, and thus regulate the biosynthesis of neurotransmitters including dopamine, norepinephrine and serotonin. Although the exact physiological functions of pteridines are still obscure, it has been suggested that neopterin might act as an endogenous inhibitor of folate synthesis in view of the major role of interferon-γ in the induction of antibacterial, anti-protozoal, and antifungal states in parasitized cells. In a clinical field, a significant elevation of urinary or serum pteridine levels has been found in patients with various malignant disorders, as well as in patients with viral diseases such as acquired immunodeficiency syndrome (AIDS). Active oxygen species such as superoxide anion radicals are thought to be potent pathogenic factors in various viral diseases, and the pathogenesis may involve not direct viral cytotoxicity and/or reactivity of active oxygen species. That is, an excess amount of active oxygen species following overreaction of immunodefense response against the virus-infected organs, may participate in the mechanism of tissue injuries observed in various types of viral diseases. Based on these reports, functional roles of neopetrin relating to the active oxygen species has easily been anticipated. In this review, neopterin as an endogenous antioxidant is described.

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The first departments of preventive medicine and hygiene in medical schools in Japan were established in the years around 1890 whereas the departments of public health were established in around 1950. Both departments were expected to serve people through researches which contribute to the people by solving the health problems in the communities. Studies in this field of medical science in Japan were initiated to prevent communicable diseases early in this century. In the field of chemical safety, the study was first focused on the prevention of industrial poisoning, management of pollution-induced diseases, measures for environmental preservation, international sharing of toxicity information, and cooperation with developing countries for the success of local efforts. The direction of the developments has been from therapy toward prevention, and solution of local problems toward international cooperation. The fields that need more attention in the nearest future from domestic viewpoints will be the studies to solve the problems due to rapid aging of the national population, and that from the viewpoints of international contribution will be the development of integrated science for not only healthy human life but sound ecosystem.

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Urine samples are known to foam and gelatinize solvent when shaken. The present work sought to develop a means of separating and characterizing urinary foaming material. A method was developed which can foam and gelatinize solvent. Human urine, after being filtered at pH 10, was bubbled at pH 4-5. The foam was shaken with n-hexane to gelatinize the solvent. The gelatinized solvent layer was washed with water several times, and dried on a glass plate ; dried material was then scraped off with a razor. A soft powder was obtained which was suggested to contain protein and sugar. The two moved together electrophoretically at the site of α-globulin, and are suggested to be a complex of protein and sugar (glycoprotein).

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The main objective of this study was to assess chromium exposure and to promote understanding of biological monitoring. Workplace activities observed involved production in a leather tannery. The urine Cr and serum Cr level in the specimens of non-occupational controls and occupational workers were determined by graphite furnace atomic absorption spectrophotometry (GFAAS). This technique includes a dilution of serum with 12 mM ultra nitric acid and 1% Triton X-100. The results showed that total serum Cr levels in the exposed occupational workers were significantly higher than those in unexposed non-occupational controls (p<0.05), and that there is a risk of chromium poisoning to the workers engaged in leather tannery worksites. The total urine Cr levels in the exposed workers were no different than in controls (p>0.05). The etiology of chromate poisoning is also briefly mentioned.

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O⁶-Methylguanine (O⁶-MeGua), formed in calf thymus DNA by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methyl-N-nitrosourea (MNU) in vitro was determined by high-performance liquid chromatography (HPLC) with electrochemical detection. The DNA treated with MNNG or MNU was hydrolyzed to nucleic bases under a mild acidic condition. O⁶-MeGua was separated from abundant normal adenine and guanine bases with a Sep-Pak C₁₈ cartridge prior to HPLC analysis. With the cartridge, the peak areas of adenine and guanine bases decreased less than 0.3% as compared to those without clean-up process, although the recovery of O⁶-MeGua through the clean-up process was more than 96%. The amount of O⁶-MeGua formed from 1μg of DNA treated with 7.3 nmol of MNNG and 14.7 nmol of MNU was 9.66 and 11.1 pmol, respectively.

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Chlorhexidine degradation by clinical isolates such as Pseudomonas aeruginosa, Pseudomonas cepacia, Alcaligenes faecalis, Alcaligenes xylosoxidans, Serratia marcescens and Pseudomonas sp. strain No. A-3 (as a control organism) was investigated after enrichment with chlorhexidine. By this enrichment, P. aeruginosa (Nos. 1-3), A. faecalis, A. xylosoxidans (No.2) and S. marcescens IFO 3046 smoothly acquired resistance to a high concentration of chlorhexidine. Among them, only S. marcescens IFO 3046 showed the same degradation pattern as the control organism, which degraded chlorhexidine via a modified degradation pathway. The other strains were thought to have a different resistance system from that of Pseudomonas sp. strain No. A-3 and S. marcescens IFO 3046.

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Acidification of blood, which is a general pretreatment procedure for cyanide analysis, caused artifactual cyanide formation from thiocyanate. A method for the determination of trace levels of blood cyanide has been developed using headspace gas chromatography with a nitrogen-phosphorus detector and a GS-Q column. By the addition of 30 mmol/l of ascorbic acid, this method eliminated thiocyanate interference. The detection limit was roughly 0.05μmol/l blood (S/N=3). Using this established method, blood cyanide levels were determined for transfusion blood samples from healthy donors, and also plasma thiocyanate levels were determined by the Konig colorimetric method. The artifactually formed cyanide levels, which were obtained by subtraction of the cyanide levels determined in the presence of ascorbic acid from those in its absence, were in proportion to the thiocyanate levels, indicating that plasma thiocyanate is oxidized to cyanide through oxyhemoglobin acidification.

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Adsorption characteristics of β-carotene from triglyceride n-hexane solution were invesitigated to elucidate the inhibition effect of trilinolein on β-carotene adsorption by attapulgites and sepiolites. The inhibition effect of trilinolein was larger than that of triolein in the initial adsorption rate and the adsorbed amount of β-carotene. Inhibition of trilinolein in maximum amount of β-carotene adsorbed on clay minerals was 1.2 times as strong as that of triolein. It was suggested that adsorption of β-carotene on clay minerals was inhibited due to binding trilinolein to β-carotene in n-hexane. The total inhibition effect was not in direct proportion to the number or the concentration of triglycerides coexisted in n-hexane.

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Effects of the acids and storage temperatures on the phospholipase A (PLase A) activities in oyster digestive glands (ODG) were investigated. The results were summarized as follows ; 1) Specific activities of both PLase A₁ and A₂ in ODG treated with acetic acid and stood at 37°C were higher than those in control group. The increase of these enzyme activities in ODG treated with 4% acetic acid (pH 2.5) was larger than those with 1% and 16% acetic acid. The enhancement of the enzyme activities in ODG was induced within 1 hr after the treatment. 2) No significant change was observed in the specific activities of PLase A₁ and A₂ in ODG treated with 0.01 N HCl (pH 2.2) and stood at 37°C throughout experimental period (5 h). The values were not different from those in control group. 3) Protein contents in all ODG samples treated with acids were lower than those in control group. The ODG treated with 4% acetic acid at 37°C had the lowest value. 4) Specific activities of both PLase A₁ and A₂ increased 3 d after the storage at 5°C. The increase of these specific activities observed until 2 weeks after the storage at 5°C was considered to be due to the decrease ofprotein contents. The degree of increase in enzyme specific activity at 3 weeks, however, was proportionally larger than that of the decrease in protein contents. No significant change was observed in PLase A activity in ODG stored at both -20°C and -70°C. 5) The optimum temperatures of PLase A₁ and A₂ were 37°C. The results showed that an increase of PLase A activity was induced in the early stage of oyster marination stood at 37°C. It was suggested that hydrolysis in phospholipid and protein denaturation would precede the enhancement of PLase A, and temperature could be one of the important factors on the enzyme activation.

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The behavior of methylated selenium metabolites in the urine and in the expiration of rats which administered orally at various dosages (0, 0.31, 1.25 and 5.00 mg Se/kg diet) of selenite, was investigated. The contents of selenium in organs depended on the dose levels. Using Sephadex gel chromatograms of rat liver cytosols it was shown that at the toxic levels the amount of selenium more than that physiologically required for the active site of GSH-Px may bind to the other site. Excretions of trimethylselenonium ion (TMSe) in the urine and dimethyl selenide (DMSe) in exhaust gas increased with increasing accumulative levels of selenium. The excretion behaviors of TMSe and DMSe for 30 d after administration showed the same content level only at toxic dosage (average selenium intake level : 95μg Se/d). The present study suggested that as exposed by deficient to nutrient levels, selenium levels and GSH-Px activity in organs may be used to evaluate selenium level in the body, and the amount of TMSe in the urine and DMSe in exhaust gas may be utilized as indicators to predict the toxic selenium exposure level.

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When the content of methanol in certain types of waterproofing aerosol products was determined according to the official method for household products containing harmful substances, the existence of an interfering substance in the products was found. The interfering substance was identified to be tert-butanol by GC-MS. In order to avoid this interference, we developed a simple headspace (HS)-gas chromatographic (GC) method. For this method, one gram of the sample sprayed into a 200 ml flask under ice cooling was weighed into a centrifugal tube. Each 10 ml of water and chloroform was added to the centrifugal tube. After shaking vigorously and centrifuging (3500 rpm, 5 min), 0.5 g of the aqueous layer was weighed into a 24 ml bottle. The bottle was incubated for 30 minutes at 25°C and then 50μl of the HS gas was injected into a GC with a fused silica capillary column coated with methyl phenyl cyanopropyl silicone. The proposed method was successfully applied to the screening analysis of methanol in 70 kinds of commercial household aerosol products.

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Indoor air pollution by chlorpyrifos and S-421 applied to building timbers for the control of termite was studied. Chlorpyrifos and S-421 in indoor air were adsorbed on silica gel by suction using a diaphragm air pump, eluted with 50 ml of acetone and determined by gas chromatograph-mass spectrometry. Chlorpyrifos and S-421 levels in indoor air ranged from 0 to 0.258 and from 0.012 to 0.174μg/m³, respectively and tended to be higher in summer with a rise in atmospheric temperature than those in other seasons. Chlorpyrifos and S-421 levels in the air of the Japanese-style room are higher than those of the wash room. The chlorpyrifos and S-421 levels were found to decrease by the use of a ventilator.

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This reports a study of the selenium (Se) content in some Astragalus (Se indicator plants), related plants (vetch), and soils in Japan. The Se content of Japanese Astragalus was 0.06-2.17 mg/kg of dry weight. The Se content in Hedysarum and Oxytropis, the species of vetch, was 0.05-2.04 mg/kg. We did not find any vetch in Japan in which Se had accumulated. Se content in plants is influenced by Se level in the soil. We measured the Se content in the surface soils in Japan and plotted a Japanese Se map ; the soil content was 0.2-1 mg/kg, except around a few volcanoes such as Tateyama Murodo (148 mg/kg) and Mt. Zao (10.0 mg/kg). We showed in detail the Se content in the soils and plants around the Tateyama Murodo region. The Se content of soils and ashes from many volcanoes such as Mt. Unzen and Mt. Pinatubo (Philippines) was low (0.1-0.6 mg/kg).

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