Homologue and isomer distribution of dioxins observed in water samples collected from Kahokugata Lagoon and inflowing rivers, Japan

Water samples were collected at 17 sites in Kahokugata Water Basin, a closed water basin in central Japan. We determined the concentration of dioxins of the water samples. Linear relationships between toxic equivalent (TEQ) concentrations of dioxin and concentrations of suspended solid (SS) were obtained at sites in Kahokugata Lagoon and in the rivers flowing into the lagoon. Homologue composition of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) indicated that all the water samples were still strongly influenced by chlorinated herbicides, such as chloronitrofen (CNP) and pentachlorophenol (PCP) that had been widely used in rice fields. The main isomer distributions of the PCDD homologues were not significantly different among the sampling sites, while the main isomer distributions of the PCDF homologues were considerably different among the sampling sites. At a few sampling points in the downstream part of one of the rivers, high concentrations of 1,3,6,7,8-pentachloro dibenzofuran (1,3,6,7,8-PeCDF) and its related isomers (1,3,6,8-chlorine-substituted PCDFs) were traced to a dye manufacturing plant. These non-toxic isomers are usually only minor constituents in environmental water samples and are not indicators of any known dioxin sources. The dyeing discharge was found to make a contribution only in the water samples collected near the plant and the seasonal variation of the contribution might depend on the flow rate of the river.     

Grassypeptolides as Natural Inhibitors of Dipeptidyl Peptidase 8 and T‐Cell Activation

Natural products made by marine cyanobacteria are often highly modified peptides and depsipeptides that have the potential to act as inhibitors for proteases. In the interests of finding new protease inhibition activity and selectivity, grassypeptolide A ( 1 ) was screened against a panel of proteases and found to inhibit DPP8 selectively over DPP4. Grassypeptolides were also found to inhibit IL‐2 production and proliferation in activated T‐cells, consistent with a putative role of DPP8 in the immune system. These effects were also observed in Jurkat cells, and DPP activity in Jurkat cell cytosol was shown to be inhibited by grassypeptolides. In silico docking suggests two possible binding modes of grassypeptolides—at the active site of DPP8 and at one of the entrances to the internal cavity. Collectively these results suggest that grassypeptolides might be useful tool compounds in the study of DPP8 function.     

Methyl Yellow: A Potential Drug Scaffold for Parkinson's Disease

Parkinson's disease (PD) is an age‐related neurodegenerative disease affecting movement. To date, there are no currently available therapeutic agents which can prevent or slow disease progression. Here, we evaluated an azobenzene derivative, methyl yellow (MY), as a potential drug scaffold for PD; its inhibitory activity toward monoamine oxidase B (MAO‐B) as well as drug‐like properties were investigated. The inhibitory effect of MY on MAO activity was determined by a MAO enzyme inhibition assay. In addition, the in vitro properties of MY as a drug candidate (e.g., blood–brain barrier (BBB) permeability, serum albumin binding, drug efflux through P‐glycoprotein (P‐gp), drug metabolism by P450, and mitochondrial toxicity) were examined. In vivo effectiveness of MY was also evaluated in the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) Parkinsonian mouse model. MY selectively inhibited MAO‐B in a dose‐dependent and reversible manner. MY was BBB‐permeable, bound relatively weakly to serum albumin, was an unlikely substrate for both systems of P‐gp and P450, and did not cause mitochondrial toxicity. Results from the MPTP Parkinsonian mouse model indicated that, upon treatment with MY, neurotoxicity induced by MPTP was mitigated. Investigations of MY demonstrate its inhibitory activity toward MAO‐B, compliant properties for drug consideration, and its neuroprotective capability in the MPTP Parkinsonian mouse model. These data provide insights into potential use, optimization, and new design of azobenzene derivatives for PD treatment.     

Influence of pH and flow on the polarisation behaviour of pure magnesium in borate buffer solutions

The influence of pH and flow on the polarisation and impedance behaviour of pure Mg was investigated in 0.6 wt% NaCl borate buffer solutions at pH 6.7, 7.6, and 9.3 using a rotating electrode. The existence of flow prevented the accumulation of the corrosion product and promoted uniform corrosion, leading to an increase of the anodic current density and a decrease of the impedance regardless of the pH of the bulk solution. The influence of the pH did not obviously appear under the static condition, whereas, under the dynamic condition, the anodic current density at pH 6.7 and 7.6 was higher than that at pH 9.3. This result suggests that pH near the surface can be buffered at the pH of bulk solution by borate buffer with the acceleration of ion diffusion.     

Enhancement of the Catalytic Activity of a Dawson-type Heteropoly Acid Induced by the Loading on a Silica Support

The Friedel–Crafts alkylation, benzylation of anisole with benzyl alcohol, was carried out over heteropoly acids (HPAs) supported on SiO₂. A Dawson-type HPA, in which Nb atoms were partially substituted with W atoms, exhibited the highest activity among various kinds of HPAs. The catalyst was reusable in the reaction after the filtration and it kept high activity even after the washing with hot water when the catalyst was calcined at 743 K. In contrast, the unsupported catalyst was almost inactive after the thermal treatment. The change in the activity was in good agreement with the degree in the acid amount measured by NH₃-TPD. Unlike the Dawson-type heteropoly acid, the activity of the Keggin-H₃PW₁₂O₄₀/SiO₂ remarkably dropped through the repeated use for the reaction. Based on the structural analysis of Dawson-type HPAs, the partially decomposed HPA on the support of SiO₂ was ascribed to the active species.     

Purification and characterization of chondroitin 4-sulfotransferase from the culture medium of a rat chondrosarcoma cell line

Chondroitin 4-sulfotransferase, which transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 4 of N-acetylgalactosamine in chondroitin, was purified 1900-fold to apparent homogeneity with 6.1% yield from the serum-free culture medium of rat chondrosarcoma cells by affinity chromatography on heparin-Sepharose CL-6B, Matrex gel red A-agarose, 3',5'-ADP-agarose, and the second heparin-Sepharose CL-6B. SDS-polyacrylamide gel electrophoresis of the purified enzyme showed two protein bands. Molecular masses of these protein were 60 and 64 kDa under reducing conditions and 50 and 54 kDa under nonreducing conditions. Both the protein bands coeluted with chondroitin 4-sulfotransferase activity from Toyopearl HW-55 around the position of 50 kDa, indicating that the active form of chondroitin 4-sulfotransferase is a monomer. Dithiothreitol activated the purified chondroitin 4-sulfotransferase. The purified enzyme transferred sulfate to chondroitin and desulfated dermatan sulfate. Chondroitin sulfate A and chondroitin sulfate C were poor acceptors. Chondroitin sulfate E from squid cartilage, dermatan sulfate, heparan sulfate, and completely desulfated N-resulfated heparin hardly served as acceptors of the sulfotransferase. The transfer of sulfate to the desulfated dermatan sulfate occurred preferentially at position 4 of the N-acetylgalactosamine residues flanked with glucuronic acid residues on both reducing and nonreducing sides.     

A quantitative assay for angiogenesis of cultured choroidal tissues in streptozotocin-diabetic Wistar and spontaneously diabetic GK rats

Tenascin-C is an extracellular matrix component which is transiently expressed in association with epithelial cell detachment, proliferation, and migration. This molecule has been identified in respiratory tissue, but little is known about the cellular source of tenascin-C or the factors that regulate its production. Since air pollutants are known to disrupt epithelial integrity, we investigated the regulation of tenascin-C in response to 0.3 ppm ozone in differentiated primate nasal epithelial cells in culture at an air-medium interface. The expression of tenascin-C was upregulated in response to ozone, as determined by Northern blot analysis, Western blotting, and immunofluorescent staining. In contrast, there was no change in the mRNA levels for versican, biglycan, perlecan, or collagen type I. Reduced cellular attachment to the substrate was evident in ozone-treated cultures in association with tenascin-C deposition at the interfaces between cells and basal surfaces. The presence of tenascin-C on denuded areas of the matrix suggests that tenascin-C may have been instrumental in the loss of patches of cells. The modulation of tenascin-C synthesis and distribution may play a significant role in the response of respiratory epithelial cells to ozone exposure.     

Effect of surface oxide layer on deuterium permeation behaviors through a type 316 stainless steel

Effect of surface oxide layer on the hydrogen isotope permeation was studied. Iron oxide was uniformly formed in the oxide layer, although chromium was limited at the interface between the oxide layer and bulk SS-316. The permeation behavior of deuterium for oxidized SS-316 was compared with that for unoxidized SS-316 at temperature range of 333–673 K. The deuterium permeability for the oxidized SS-316 was reduced 1/10–1/20 times as high as that for unoxidized one. However, the activation energy of deuterium permeation as gas form for oxidized SS-316 was almost the same as that for unoxidized SS-316 and was 0.64 eV, which was almost consistent with the sum of activation energies for diffusion and solubility. This fact indicates that the deuterium permeation is diffusion limited. The permeability of deuterium as water form was almost constant even if heating temperature is high, showing that the deuterium was permeated through bulk SS-316 and react with oxygen at the oxide layer as water desorption, which is controlled by the permeation flux of deuterium and oxygen concentration on the surface of oxide layer in downstream side.     

Heteropolyacid-conjugated chitosan matrix for triphase catalyst

H₃PW₁₂O₄₀ (12-phosphotungstic acid; PWA) is efficient catalysts for the selective oxidation of alkanes, aldehydes, and perfluorinated acids. However, PWA molecules are high solubility in water and this property has been making it difficult to utilize as an industrial catalyst. In this study, the water-insoluble PWA-conjugated chitosan matrix was prepared by mixing the aqueous PWA and chitosan solutions. This conjugate matrix was constructed by the electrostatic interaction between amino group of chitosan and negative charge of PWA and showed the thermal stability at <100 °C. In addition, the PWA-conjugated chitosan matrix indicated the property for triphase catalyst as epoxidation of allylic alcohols, such as cinnamyl alcohol, farnesol, and so on. The isolated yield of epoxidation with the conjugate matrix was as same as that of pure PWA. Furthermore, since this conjugate matrix did not dissolve in water, matrices could easily separate from the reaction solvent and recycle more than 3 times. Therefore, the PWA-conjugated chitosan matrices may have a potential to utilize the novel catalyst for the epoxidation of various allylic alcohols.