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The imbalance of gut microbiota is known to be associated with inflammatory bowel disease, but it remains unknown whether dysbiosis is a cause or consequence of chronic gut inflammation. In order to investigate the effects of gut inflammation on microbiota and metabolome, the sequential changes in gut microbiota and metabolites from the onset of colitis to the recovery in dextran sulfate sodium-induced colitic mice were characterized by using meta 16S rRNA sequencing and proton nuclear magnetic resonance (1H-NMR) analysis. Mice in the colitis progression phase showed the transient expansions of two bacterial families including Bacteroidaceae and Enterobacteriaceae and the depletion of major gut commensal bacteria belonging to the uncultured Bacteroidales family S24-7, Rikenellaceae, Lachnospiraceae, and Ruminococcaceae. After the initiation of the recovery, commensal Lactobacillus members promptly predominated in gut while other normally abundant bacteria excluding the Erysipelotrichaceae remained diminished. Furthermore, 1H-NMR analysis revealed characteristic fluctuations in fecal levels of organic acids (lactate and succinate) associated with the disease states. In conclusion, acute intestinal inflammation is a perturbation factor of gut microbiota but alters the intestinal environments suitable for Lactobacillus members.

Radical cations of pyrene were investigated by the pulse radiolysis technique in solutions of benzonitrile, acetone, and dichloroethane. A 450-nm absorption band of a pyrene monomer cation was replaced by new bands with maxima at 500, 580, and 750 nm as the pyrene concentration was increased. The latter absorption bands were exclusively assigned to a pyrene dimer cation in equilibrium with the monomer cation at room temperature. Equilibrium constants evaluated were (2.7 ±0.2) X 10 2 and (5.1±0.5) X 102M~1 at 20°C for benzonitrile and acetone solutions, respectively. The decay processes of both the monomer and dimer cations were discussed. In addition, rate constants of the reactions of both the monomer and dimer cations with triethylamine were found to be 2.7XI09 and 5.4X108JI~1·sec-l, respectively.

The effect of temperature on the absorption spectra of the solvated electron in various liquid alcohols is reported. From 25° to −78°C, the energy corresponding to the absorption maximum increases by 0.23, 0.35, 0.36, and 0.46 eV for methanol, ethanol, isopropanol, and n-butanol, respectively. Within experimental error there is no change in the width (in electron volts) of the absorption at half-maximum. The absorption spectra of the solvated electron in several binary mixtures at room temperature are reported. In all mixtures examined the spectrum has only one peak at wavelengths intermediate to the absorption maxima of the pure components, and the exact position depends on the mixture composition. In 50:50 mixtures of many of the materials used, the absorption maxima and half-widths are closer to those of one pure component than of the other. The fact that there is no evidence of two peaks in mixtures indicates that the solvation of the electron depends on the macroscopic properties of the solution in the sense that a particular electron interacts significantly with a large number of solvent molecules. However, the results indicate that at least in some mixtures the electron is associated on a microscopic scale preferentially with one component. Partial spectra, at low temperature, of the solvated electron in the liquids diethyl ether, monomethylamine, and monoethylamine are also reported.

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The reactions of the triplet state of 4-nitroquinoline 1-oxide (4NQO) with a series of amino acids and some proteins in aqueous solutions have been studied by using a laser flash technique. Only tryptophan (TrpH) and tyrosine (TyrOH) among a series of amino acids quench the triplet 4NQO (T4NQO) at a diffusion-controlled rate. Lysozyme, ribonuclease, and histone, which contain TrpH and/or TyrOH residues, had rate constants comparable to those of TrpH and TyrOH. The formation of the H adduct of 4NQO (4NQOH*), which may be produced by the reaction of 4NQO" with water, was confirmed from the transient absorption spectra for 4NQO solutions containing these quenchers. The transient absorption spectra observed for TrpH and TyrOH solutions elucidated the formation of the deprotonated forms of TrpH+ and TyrOH"1" (Trp* and TyrO') together with 4NQOH*. The result demonstrates that the electron transfer from TrpH or TyrOH to T4NQO occurs in the triplet quenching by TrpH or TyrOH. Since the almost same transient spectra as Trp* and TyrO* were observed for lysozyme and ribonuclease solutions, respectively, TrpH residues on lysozyme and TyrOH residues on ribonuclease are main quenching sites, where electron transfer and deprotonation occur. The quantum yields of T4NQO, 4NQOH*, Trp*, and TyrO" produced by the excitation of the 4NQO solution containing TrpH or TyrOH with a 355-nm light pulse were determined to be 0.46, 0.47, 0.41, and 0.41, respectively. The result shows that the efficiency in electron transfer from TrpH or TyrOH to T4NQO is ~90%. For the reaction of T4NQO with methionine, arginine, histidine, lysozyme, or ribonuclease, the efficiency in electron transfer was also estimated to be nearly equal to that for the reaction with TrpH or TyrOH.