A Major Intestinal Catabolite of Quercetin Glycosides, 3-Hydroxyphenylacetic Acid,Protects the Hepatocytes from the Acetaldehyde-Induced Cytotoxicity through the Enhancement of the Total Aldehyde Dehydrogenase Activity

Aldehyde dehydrogenases (ALDHs) are the major enzyme superfamily for the aldehyde metabolism. Since the ALDH polymorphism leads to the accumulation of acetaldehyde, we considered that the enhancement of the liver ALDH activity by certain food ingredients could help prevent alcohol-induced chronic diseases. Here, we evaluated the modulating effects of 3-hydroxyphenylacetic acid (OPAC), the major metabolite of quercetin glycosides, on the ALDH activity and acetaldehyde-induced cytotoxicity in the cultured cell models. OPAC significantly enhanced the total ALDH activity not only in mouse hepatoma Hepa1c1c7 cells, but also in human hepatoma HepG2 cells. OPAC significantly increased not only the nuclear level of aryl hydrocarbon receptor (AhR), but also the AhR-dependent reporter gene expression, though not the nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent one. The pretreatment of OPAC at the concentration required for the ALDH upregulation completely inhibited the acetaldehyde-induced cytotoxicity. Silencing AhR impaired the resistant effect of OPAC against acetaldehyde. These results strongly suggested that OPAC protects the cells from the acetaldehyde-induced cytotoxicity, mainly through the AhR-dependent and Nrf2-independent enhancement of the total ALDH activity. Our findings suggest that OPAC has a protective potential in hepatocyte models and could offer a new preventive possibility of quercetin glycosides for targeting alcohol-induced chronic diseases.     

Fabrication of tin-filled carbon nanofibres by microwave plasma vapour deposition and their in situ heating observation by environmental transmission electron microscopy

Sn-filled carbon nanofibres (CNFs) are fabricated by microwave plasma chemical deposition. Scanning electron microscopy observations revealed the existence of a Sn island under the CNFs. The structure of the CNFs is investigated, and the behaviour of Sn in the internal space of CNFs is revealed by performing in situ heating observations by environmental transmission electron microscopy (ETEM). ETEM observations reveal that they have low-crystallized carbon wall and Sn occupies not only the CNF’s internal space but also its carbon wall. The Sn inside the CNF is completely covered by the carbon wall. Further, the in situ heating observations reveal that Sn within the internal space and the carbon wall of the CNFs diffused to the outside during heating. Moreover, it is found that higher membered carbon rings and defects in the graphite layer act as diffusion routes between disordered carbon layers.     

Synthesis of polyvinyl alcohol stereoblock copolymer via the combination of living cationic polymerization and RAFT/MADIX polymerization using xanthate with vinyl ether moiety

Different types of novel xanthates containing a vinyl ether moiety, S-benzyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 1) and S-1-(ethoxycarbonyl)ethyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 2) were synthesized. In particular, the Xanthate 2 enabled to design polyvinyl alcohol (PVA) stereoblock copolymer via the combination of living cationic vinyl polymerization and RAFT/MADIX polymerization. For cationic polymerization of isobutyl vinyl ether (IBVE) and tert-butyl vinyl ether (TBVE), the polymerizations were conducted under Xanthate 1-HCl adduct/SnCl₄ and Xanthate 1 or 2-CF₃COOH adduct/EtAlCl₂ initiating system in the presence of ethyl acetate. Both systems proceeded in living polymerization fashion because the calculated M_n of both poly(IBVE) and poly(TBVE) matches with the M_n polymerized assuming that one polymer chain is formed per one molecule of the Xanthate 1 or 2. The resulting poly(TBVE) had a high number average α-end functionality as determined by MALDI-TOF-MS spectrometry. Xanthate 2 is more efficient for the following RAFT/MADIX polymerization of vinyl acetate (VAc). The RAFT/MADIX polymerization of vinyl acetate (VAc) using azobis(isobutyronitrile) (AIBN) at 60 °C was conducted using either poly(IBVE) or poly(TBVE) macro-CTA. The poly(TBVE) macro-CTAs synthesized from the Xanthate 2 were able to polymerize VAc smoothly via RAFT/MADIX polymerization, to prepare well-defined diblock copolymer, poly(TBVE)-b-poly(VAc). The resulting block copolymer was then hydrolyzed using KOH in methanol and followed by acid hydrolysis using HBr gas bubbling. The resulting polymer is inherently stereoblock like copolymer, isotactic rich PVA-b-atactic PVA (iPVA-b-aPVA). From the DSC measurement, the iPVA-b-aPVA has one glass transition at 69.5 °C and two melting points according to iPVA and aPVA at 237.9 and 198.1 °C, respectively. Thus, it can be suggested that the obtained PVA has two different geometries by the combination of living cationic polymerization and RAFT/MADIX polymerization.     

Production and purification of a bacteriocin peptide produced by Lactococcus sp. strain GM005, isolated from Miso-paste

Lactococcus sp. GM005 was isolated from Miso-paste and was found to produce a bacteriocin with strong antibacterial activity. A culture of Lactococcus sp. GM005, maintained at 30 degrees C and a constant pH of 6.0, exhibited bacteriocin activity eightfold higher than that of a culture grown under pH-uncontrolled conditions. GM005 bacteriocin was purified to homogeneity on SDS-PAGE by hydrophobic column chromatography and gel filtration. The estimated molecular weight of GM005 bacteriocin was approximately 9.6 kDa based on gel-filtration analysis, and was approximately 2.4 kDa based on tricine-SDS-PAGE analysis, indicating a tetrametric structure. N-terminal amino acid analysis revealed that the N-terminal end was blocked. Amino acid composition analysis revealed a high proportion of hydrophobic amino acid residues and lanthionine. This differs from the composition of some antibiotics. GM005 bacteriocin exhibits a bactericidal activity against Lactobacillus sakei JCM1157T.     

Analysis of thickening polysaccharides by the improved diethyldithioacetal derivatization method

The identification test for thickening polysaccharides containing neutral saccharides and uronic acids was investigated by GC analysis of constituent monosaccharides. The reported method, in which monosaccharides were converted to diethyldithioacetal derivatives with ethanethiol followed by trimethylsilylation, was improved in terms of operability and reproducibility of GC/MS analysis. The suitability of the improved diethyldithioacetal derivatization method was determined for seven thickening polysaccharides, i.e., carob bean gum, guar gum, karaya gum, gum arabic, gum ghatti, tragacanth gum and peach gum. The samples were acid-hydrolyzed to form monosaccharides. The hydrolysates were derivatized and analyzed with GC/FID. Each sugar derivative was detected as a single peak and was well separated from others on the chromatograms. The amounts of constituent monosaccharides in thickening polysaccharides were successfully estimated. Seven polysaccharides were distinguished from each other on the basis of constituent monosaccharides. Further examination of the time period of hydrolysis of polysaccharides using peach gum showed that the optimal times were not the same for all monosaccharides. A longer time was needed to hydrolyze glucuronic acid than neutral saccharides. The findings suggest that hydrolysis time may sometimes affect the analytical results on composition of constituent monosaccharides in polysaccharides.     

CFD analysis of the convection flow in the pan during induction heating and gas range heating

One difference between induction heating (IH) and gas range heating (GRH) is that, because the heating location of the pan is different, the convection in the pan is different. In particular, in cooking situations in which solids are mixed with liquids, such as the boiling of soup containing solid foods, the natural convection flow in the pan may affect food quality. The convection in the pan during IH and GRH was analyzed by using computational fluid dynamics (CFD), and the temperature distribution and the flow velocity distribution in the pan were obtained. These results were then compared with the measurement results. In GRH, the heat flux at the wall of the pan was obtained by experiment, and it was used for the analysis as a boundary condition. In IH, the heat generation distribution obtained by electromagnetic field analysis was used for the analysis as the boundary condition. Differences in convection flow in the pan during IH and GRH were observed by CFD modeling especially at the initial stage of heating. The simulated convection in the pan showed the same tendency as the captured movement of the tracer particle using flow visualization.     

Experimental investigation of distributed navigation and collision avoidance for a robotic swarm

Artificial Life and Robotics - In this study, we focus on the navigation of a robotic swarm and perform an experimental investigation. A decentralized control method using only local information...