In view of pathological roles of leukotrienes a potent selective inhibitor of arachidonate 5-lipoxygenase was developed on the basis of an earlier finding that flavonoids suppressed anaphylactic reactions. 5-Hexyloxy-3',4'-dihydroxy-6,7-dimethoxyflavone 4'-disodium phosphate as a 5-lipoxygenase inhibitor inhibited in vivo production of peptidoleukotrienes in the gerbil brain subjected to ischemia and reperfusion. The monoclonal antibodies raised against 12- and 5-lipoxygenases and cyclooxygenase were utilized for development of peroxidase-linked immunoassays of these enzymes, which allowed a quantitative determination of the enzyme amount rather than the enzyme activity. The method was applied to lipoxygenase screening in various animal tissues. A clinical case of cyclooxygenase abnormality was analyzed by the enzyme immunoassay.

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A facultative methylotroph, Protaminobacter ruber, classified as nonphotosynthetic bacteria formed bacteriochlorophyll as well as vitamin B_<12> and cytochrome. The mode of bacteriochlorophyll formation was very unique, since oxygen was absolutely required for its synthesis and continuous exposure to light blocked it completely even at very low light intensity. Bacteriochlorophyll was not only formed in the dark, but also inducibly formed most abundantly by cultivating the bacterium in the dark after exposure to light during the relatively early stage of the growth. The regulation of tetrapyrrole biosyntheses including bacteriochlorophyll synthesis was examined in terms of 5-aminolevulinic acid (ALA) synthase. The two fractions of ALA synthase activity were obtained by Sepharose 6B column chromatography and the presence of an isozyme was demonstrated by the difference of two fractions in molecular weight, optimal pH and the effect of end-product such as hemin and vitamin B_<12> derivatives. One enzyme was formed inducibly in fairly good agreement with bacteriochlorophyll formation. The other constitutive enzyme seems to participate mainly in vitamin B_<12> and cytochrome formation.

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Methods of treatment and extraction of porcine blood were investigated for measurement of vitamin B_<12> (B_<12>) using a mutant of Escherichia coli which requires B_<12> for growth. B_<12> Values in whole blood treated with heparin, heparinized plasma and serum were almost the same, but those in plasma treated with EDTA were approximately 1.5 times as high as those by other treatments. The values of B_<12> were stable in the acetate buffer adjusted at pH 4.5-5.0, and not affected by addition of 0.5ml or less of KCN. The recovery of B_<12> by the boiling method was higher than that by the autoclave procedure, and the variance coefficients of the values obtained were lower in the former. The same value of B_<12> was obtained regardless of addition of meta-phosphoric acid. Almost constant B_<12> values were obtained until 7 days after sampling when serum and B_<12> extracts were stored below 4℃.

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A new high-perfomance liquid chromatography method and the conventional method of N^1-methylnicotinamide measurement were compared in analysis of urinary N^1-methylnicotinamide excretion in women's students. The N^1-methylnicotinamide value measured by the conventional method was 29.77 ±12.04μmol/daily urine (mean±SD, n=30), and that measured by the new method was 30.55±12.56μmol/daily urine. The correlation coefficient between the values obtained by the two methods was 0.972 (p<0.001), and the regression line was N^1-methylnicotinamide (new method, μmol/daily urine) = 1.015×N^1-methylnicotinamide (conventional method,μmol/daily urine) +0.342. These results show that the N^1-methylnicotinamide values obtained by the new method could be directly comparable with those obtained by the conventional method.

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