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The monolayers of thiol-functionalized viologens, i.e., dihexafluorophosphate salts of N-butyl-N‘-(4-mercaptobutyl)-4,4‘-bipyridinium (C4V2+C4SH) and N-pentyl-N‘-(5-mercaptopentyl)-4,4‘-bipyridinium (C5V2+C5SH), on a polycrystalline gold electrode were characterized in several aqueous electrolyte solutions using cyclic voltammetry and electroreflectance (ER) spectroscopy. The voltammetric response for the viologen dication/radical cation couple (V2+/V•+) in Na2SO4, K2SO4, KPF6, or KF solution was found to be electrolyte anion dependent. However, considerable differences due to the electrolyte anion or the alkyl chain length in the fractional content of dimer forms in the V•+ state and the average orientation of the V•+ moiety, both estimated from the results of ER spectral measurements, were not observed. A large voltammteric peak width was observed in KF solution. Because the voltammetric measurements suggested a strong and weak binding to the viologen moiety respectively for PF6 - and F- ions, the dependence of voltammetric response on the concentration of PF6 - was investigated quantitatively for a monolayer of C4V2+C4SH in the mixed solutions of KPF6 and KF at a constant ionic strength. It was found that one PF6 - ion additionally binds to a viologen moiety upon the oxidation of V•+ to V2+. The ratio of the binding constant to V2+ and V•+ was estimated to be approximately 1.2 × 104 M-1 at an ionic strength of electrolyte of 0.4 M. The absence of considerable dependence of the PF6 - binding on the ionic strength was suggested by voltammetric measurements in the solutions containing solely KPF6. The electron-transfer rate constants for the monolayers were estimated to be no less in the order of magnitude than 1 × 104 s-1.

In order to study the relationship between cysteine protease and Der f l, which is one of the major allergens in the mite, Dermatophagoides farinae, isolation of cysteine protease was attempted using various column chromatographies. Both the potent cysteine protease activity and the allergenic activity were detected in the same fractions by anion exchange chromatography on a DEAE-Sephacel, gel chromatographies and chelating Sepharose 6B chromatography. In the double immunodiffusion test, the finally isolated fraction and rabbit anti-Der f I sera reacted to give a single precipitation line which fused completely with the precipitation line formed by Der f l and anti-Der f l sera. Sequence analysis for the first 10 N-terminal amino acids from cysteine protease and Der f l were identical. These results strongly suggest that cysteine protease of mites may be Der f l allergen and that measuring cysteine protease activity may possibly become a beneficial method for detecting Der f I allergens.

Previous studies have shown the physiological significance of dietary conjugated linoleic acid (CLA) in various experimental animals and in human beings. One of the important problems to better elucidate is the difference between triglyceride (TG) and free (FFA) dietary CLA. Here, using splenocytes, this study assesses how TG- and FFA-CLA modulate immunoglobulin and various cytokine productions. In this study, C57BL/6N mice were fed an experimental diet containing 0% CLA, 0.1 or 1% FFA-CLA, or 0.1 or 1% TG-CLA for 3 weeks. The production of immunoglobulin tended to be up-regulated by 1% FFA-CLA. As a result of protein array analysis using the supernatant from splenocytes cultured with no CLA, 1% FFA-CLA, and TG-CLA, some cytokine production was shown to be remarkably regulated by dietary FFA- and TG-CLA. A total of 32 cytokines were examined, and 11-14 produced cytokines that were 2-fold up-regulated as compared with control for FFA- or TG-CLA, respectively. Especially, the production of IL-9 and MCP-5 and other cytokines was remarkably up-regulated by both FFA- and TG-CLA. In addition, seven cytokines were 2-fold down-regulated by TG-CLA. These data show that there is a slight but significant difference between the functionalities of FFA- and TG-CLA.

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