High-performance Liquid Chromatography of Aflatoxins with Fluorescence Detection

Aflatoxins B_l, B₂, G₁ and G₂ were quantitatively detected by high-performance liquid chromatography on a 12 µl flow-cell in the fluorometric detector using the mobile phase of toluene system instead of chloroform, dichloromethane or methanol system. Various kinds of columns and mobile phases were tested, and fine mutual separation of all the four aflatoxins without quenching their fluorescence was achieved by using sHica gel column and toluene- ethyl acetate-formic acid-methanol (89.0: 7.5: 2.0: 1.5 v/v/v/v). The relationship between the fluorescence peak area and the amount injected was linear in the range of 0.3 ng to 120 ng. This method, as applied to food and feed extracts, is sensitive at the 10~20 ppb levels of the four kinds of aflatoxins.     

Synthesis of cytochrome c oxidase in the liver of Rana catesbeiana tadpole treated with griseofulvin

The effect of griseofulvin treatment on the synthesis of cytochrome c oxidase was studied with the liver of the tadpole, Rana catesbeiana. (1) In the liver of tadpole treated with griseofulvin, a ferrochelatase inhibitor, the synthesis of heme a, but not cytochrome c oxidase protein, is inhibited. (2) The apocytochrome c oxidase which is formed in the liver of tadpole treated with griseofulvin is converted to the active holoenzyme by exogenously added heme a.     

Structure-activity relations of inhibitory effects of various flavonoids on lipopolysaccharide-induced prostaglandin E2 production in rat peritoneal macrophages: comparison between subclasses of flavonoids.

A study of the structure-activity relations of the inhibitory effect of flavonoids on lipopolysaccharide (LPS)-induced prostaglandin production was carried out via a comparative examination of 39 flavonoids and related compounds. A comparison of the subclasses showed that flavones were most effective, followed by flavanones. Flavonols were less effective than those two groups. These results suggest that the C2-C3 double-bond and 4-oxo functional group of the C-ring are important factors for the high inhibition activities. Flavonoids showed the strongest inhibitory effect on the expression of Cox-2 protein. These results help to explain part of the reason for the pharmacological efficacy of flavonoids as anti-inflammatory compounds.     

Relationship between surface marker expression and encephalitogenic potency of BP-cultured lymphocytes

The relationship between surface marker expression and encephalitogenicity of lymphocytes from various lymphoid organs of Lewis rats was studied. The encephalitogenicities after culture with BP were spleen cells greater than lymph node cells much greater than thymus cells, in this descending order. The cells from every lymphoid organ proliferated significantly in response to BP. In spleen and lymph node cells, the expression of W3/25 and OX-3 molecules on T cells increased markedly after culture with BP, but the expression of OX-19 or OX-8 molecules did not change significantly. The up-regulations of W3/25 and OX-3 molecules were more pronounced in spleen cells than in lymph node cells. Thymus cells also showed a significant increase in the W3/25 molecule after the culture with BP. Therefore, T cells from all the lymphoid organs showed a selective up-regulation of the W3/25 molecule after culture with BP, and the degree of the up-regulation seems to correspond to the encephalitogenic potency in vivo. Since the W3/25 molecule apparently plays a direct role in the effector phase of experimental allergic encephalomyelitis (EAE) by enhancing BP-reactive T cell/antigen-presenting cell interaction in the central nervous system, the up-regulation on BP-cultured T cells may strengthen interaction with the class II major histocompatibility complex molecule on antigen-presenting cells, and therefore, contribute to the efficient transfer of EAE.     

Sex difference in susceptibility to teratogenic effect of maternal biotin deficiency in mouse embryos

When pregnant mice were fed biotin-deficient diets, cleft palate occurred more frequently in male fetuses than in female fetuses. Possible underlying mechanisms are speculated on, and some methodological problems in the analysis of sex-related differences in multiparous animals are discussed.