Comparison of DNA sequencing analysis with phenotyping test for identification of yeasts isolated from foods

The identification of 20 strains of yeasts isolated from foods by means of DNA sequence analysis with two kinds of universal primers for the rDNA region was examined, and the results were compared with those of the conventional phenotyping test using API 20C AUX. In the analysis of the 26S region, all 20 yeast strains tested were identified at the species level. In the ITS1 region, 16 strains were also classified at the species level. In addition, all results of DNA sequence analysis were consistent with those of the phenotyping test at the genus level. Furthermore, DNA sequence analysis was able to identify causative yeasts observed in two suspect foods, though phenotyping tests alone failed to identify them.     

Stabilizing effect of the cyclodextrins additive to spray-dried particles of curcumin/polyvinylpyrrolidone on the supersaturated state of curcumin

Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD.     

Preparation of microporous polypropylene sheets containing CaCO3 filler: Effect of draft ratio

Microporous polypropylene sheets were prepared as follows. First, polypropylene pellet-containing CaCO₃ filler was extruded to prepare base sheets, which were then biaxially stretched. The draft effect at the extrusion process was studied in relation to some properties of the resultant microporous polypropylene sheets. © 1996 John Wiley & Sons, Inc.     

Microporous polypropylene fibers containing poly(methylsilsesquioxane) filler

Microporous polypropylene fibers were prepared by stretching polypropylene fibers containing poly(methylsilsesquioxane) filler. The properties of the resultant fibers are controllable by adjusting the filler content and stretching degree. The resultant fibers have a fine texture of polypropylene fibrils, in which the filler particles are dispersed. Some properties were investigated: tensile strength, elongation, Young's modulus, porosity, pore size, and specific surface area. © 1996 John Wiley & Sons, Inc.     

Mouse Gastric Epithelial Cells Resist CagA Delivery by the Helicobacter pylori Type IV Secretion System

The initial step in bacterial infection is adherence of the bacterium to the target cell surface. Helicobacter pylori exploits the interaction of bacterial adhesin protein HopQ with human epithelial CEACAMs (CEACAM1, 5, and 6) to stably adhere to gastric epithelial cells, which is necessary for delivery of the H. pylori CagA oncoprotein into the epithelial cells via a type IV secretion system. In contrast to human CEACAMs, however, HopQ does not interact with Ceacam1 (mouse CEACAM1) in vitro or in CHO cells ectopically expressing Ceacam1. Since the mouse genome lacks Ceacam5 and Ceacam6, no significant HopQ–Ceacam interaction may occur in mouse gastric epithelial cells. Here, we found that the mouse stomach has a much lower expression level of Ceacam1 than the expression level of CEACAM1 in the human stomach. Consistently, mouse gastric epithelial cells resist CagA delivery by cagA-positive H. pylori, and the delivery is restored by ectopic expression of human CEACAM1 or CEACAM5 in mouse gastric epithelial cells. Thus, despite the fact that mice are routinely used for H. pylori infection studies, a low expression level of Ceacam1 in the mouse stomach together with the loss or greatly reduced interaction of HopQ with Ceacams make the mouse an inappropriate model for studying the role of H. pylori-delivered CagA in gastric pathogenesis, including the development of gastric cancer.     

Deposition of Lead Phosphate by Lead-Tolerant Bacteria Isolated from Fresh Water near an Abandoned Mine

Specialist bacteria can synthesize nanoparticles from various metal ions in solution. Metal recovery with high efficiency can be achieved by metal-tolerant microorganisms that proliferate in a concentrated metal solution. In this study, we isolated bacteria (Pseudomonas sp. strain KKY-29) from a bacterial library collected from water near an abandoned mine in Komatsu City, Ishikawa Prefecture, Japan. KKY-29 was maintained in nutrient medium with lead acetate and synthesized hydrocerussite and pyromorphite nanoparticles inside the cell; KKY-29 also survived nanoparticle synthesis. Quantitative PCR analysis of genes related to phosphate metabolism showed that KKY-29 decomposed organic phosphorus to synthesize lead phosphate. KKY-29 also deposited various metal ions and synthesized metal nanoparticles when incubated in various metal salt solutions other than lead. The present study considers the development of biotechnology to recover lead as an economically valuable material.     

Molecular Hydrogen Enhances Proliferation of Cancer Cells That Exhibit Potent Mitochondrial Unfolded Protein Response

Molecular hydrogen ameliorates pathological states in a variety of human diseases, animal models, and cell models, but the effects of hydrogen on cancer have been rarely reported. In addition, the molecular mechanisms underlying the effects of hydrogen remain mostly unelucidated. We found that hydrogen enhances proliferation of four out of seven human cancer cell lines (the responders). The proliferation-promoting effects were not correlated with basal levels of cellular reactive oxygen species. Expression profiling of the seven cells showed that the responders have higher gene expression of mitochondrial electron transport chain (ETC) molecules than the non-responders. In addition, the responders have higher mitochondrial mass, higher mitochondrial superoxide, higher mitochondrial membrane potential, and higher mitochondrial spare respiratory capacity than the non-responders. In the responders, hydrogen provoked mitochondrial unfolded protein response (mtUPR). Suppression of cell proliferation by rotenone, an inhibitor of mitochondrial ETC complex I, was rescued by hydrogen in the responders. Hydrogen triggers mtUPR and induces cell proliferation in cancer cells that have high basal and spare mitochondrial ETC activities.     

Effect of matrix's type on the dynamic properties for short fiber-elastomer composite

The dynamic moduli, E′ and E″, and tan δ for PET–CR, PET–EPDM, and PET–UR composites with unidirectional short fibers were studied as a function of temperature by using a Rheovibron. The temperature dependence of tan δ showed three peaks for PET–elastomer composites. The peaks at the low temperature corresponded to the main dispersion of the respective matrixes and the peak at about 140°C to the α-dispersion of PET fiber. A small and broad peak observed at a temperature between 60 and 120°C may be caused by the relaxation of the interface region between fibers and matrix. The longitudinal storage modulus for the composite E was given by the parallel model as \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm E'}_\parallel = V_f \cdot E'_f + V_m \cdot E'_m $\end{document}, where E and E are the storage moduli for fiber and matrix and V_f and V_m are the volume fraction of fiber and matrix, respectively. In the transverse direction of fibers, the composite modulus E was expressed by the logarithmic law of mixing as follows: \documentclass{article}\pagestyle{empty}\begin{document}$ \log E'_ \bot = V_f \cdot \log E'_f + V_m \cdot \log E'_m $\end{document}. The peak values of tan δ from the main dispersion of the respective matrixes were given by the equation, (tan δ_⊥max)_c/(tan δ_max)_m 1 ? β · V_f, where (tan δ_⊥max)_c and (tan δ_max)_m are the maximum values of the loss tangent for the composite and matrix, respectively, and β is coefficient depending on matrix's type. The β value of PET–CR composite is the largest one among those of the composites.     

Indentation-induced ductile behavior of glass–ceramics involving layered aluminosilicates

Contact damage in materials is critical in engineering applications because it influences mechanical resistance, such as wear, erosion, and impact failure. Indentation tests were performed using a tungsten carbide ball indenter (Hertzian contact) on the surfaces of glass–ceramics containing hexagonal CaAl₂Si₂O₈ or mica crystals (fluorophlogopite), both of which have a layered structure. The stress–strain relation and the permanent deformation on the surface, as well as the observation of the microcrack zone by X-ray computed tomography using synchrotron radiation, revealed that the glass–ceramic with hexagonal CaAl₂Si₂O₈ showed ductility similar to the quasi-plastic behavior previously observed in the mica glass–ceramic. The yield stresses of the glass–ceramics were estimated from the stress deviating from the stress–strain relation assuming complete elastic response between the ball and the sample. The ratio of the yield stress to Young modulus (Y/E) of the glass–ceramic with hexagonal CaAl₂Si₂O₈ was determined to be higher than that of the mica glass–ceramic.     

Residual stress versus microstructural effects on the strength and toughness of phase-separated PbO–B2O3–Al2O3 glasses

A few authors have reasonably proposed that liquid–liquid phase-separated (LLPS) glasses could show improved fracture strength, S_f, and toughness, K_Ic, as the second phase could provide a barrier to crack propagation via deflection, bowing, trapping, or bridging. Due to the associated tensile or compressive residual stresses, the second phase could also act as a toughening or a weakening mechanism. In this work, we investigated five glasses of the PbO–B₂O₃–Al₂O₃ system spanning across the miscibility gap: Four of them undergo LLPS—three are binodal (two B₂O₃-rich and one PbO-rich) and one is spinodal—and one does not show LLPS (composition outside the miscibility gap). Their compositions were designed in such a way that the amorphous particles are under compressive residual stresses in some and under tensile residual stresses in others. The following mechanical properties were determined: the Vickers hardness, ball on three balls (B3B) strength, and toughness, K_Ic-SEVNB (single-edge V-notch beam [SEVNB]). The microstructures and compositions were analyzed using scanning electron microscopy with energy-dispersive X-ray spectrometry. The spinodal glass showed, by far, the best mechanical properties. Its K_Ic-SEVNB = 1.6 ± 0.1 MPa m^1/2, which embodies an increase of almost 50% over the B₂O₃-rich binodal composition, and 90% considering the PbO-rich binodal composition. Moreover, its fracture strength, S_f = 166 ± 7 MPa, is one of the highest ones ever reported for an LLPS glass. Fracture analyses evidenced that the spinodal composition exhibited the lowest net stress at the fracture point. Moreover, calculations indicate that the internal residual stress level is the lowest in the spinodal glass. The overall results indicate that the microstructural effect of the spinodal glass is the most significant factor for its superior mechanical properties. This work corroborates the idea that LLPS provides a feasible and stimulating solution to improve the mechanical properties of glasses.