Structure and expression of the human SM22alpha gene, assignment of the gene to chromosome 11, and repression of the promoter activity by cytosine DNA methylation

The pore-forming alpha 1 subunit of L-type calcium (Ca2+) channels is the molecular target of Ca2+ channel blockers such as phenylalkylamines (PAAs). Association and dissociation rates of (-)devapamil were compared for a highly PAA-sensitive L-type Ca2+ channel chimera (Lh) and various class A Ca2+ channel mutants. These mutants carry the high-affinity determinants of the PAA receptor site in a class A sequence environment. Apparent drug association and dissociation rate constants were significantly affected by the sequence environment (class A or L-type) of the PAA receptor site. Single point mutations affecting the high-affinity determinants in segments IVS6 of the PAA receptor site, introduced into a class A environment, reduced the apparent drug association rates. Mutation I1811M in transmembrane segment IVS6 (mutant AL25/-I) had the highest impact and decreased the apparent association rate for (-)devapamil by approximately 30-fold, suggesting that this pore-lining isoleucine in transmembrane segment IVS6 plays a key role in the formation of the PAA receptor site. In contrast, apparent drug dissociation rates of Ca2+ channels in the resting state were almost unaffected by point mutations of the PAA receptor site.     

Leaching and cytotoxicity of formaldehyde and methyl methacrylate from acrylic resin denture base materials

Acrylic resin dentures have the potential to elicit irritation, inflammation, and an allergic response of the oral mucosa. Studies of substances leachable from acrylic resins, their cytotoxicity to cultured cells, and means of reducing their leaching were systematically conducted. Under in vivo and in vitro conditions, formaldehyde and methyl methacrylate were significantly leached into human saliva and saliva-substitute buffer, especially from autopolymerized resins. Both leachable substances showed cytotoxic potentials in the range of their leaching concentrations. Formaldehyde was cytotoxic at lower concentrations than methyl methacrylate. Preleaching in water reduced subsequent leaching of both formaldehyde and methyl methacrylate, and the amount of reduction depended on an increase in the preleaching temperatures. Immersion of acrylic resin dentures in hot water (50 degrees C) before insertion is recommended, especially for autopolymerized resins used either for rebasing or as denture base materials, to minimize the risk of adverse reactions in patients who wear acrylic resin dentures.     

Combined addition of glutathione and iron chelators for decrease of intracellular level of reactive oxygen species and death of Chinese hamster ovary cells

The combined addition of reduced form of glutathione (GSH) and iron chelators for decrease of the intracellular level of reactive oxygen species (ROSs) and death of Chinese hamster ovary (CHO) cells was investigated. The addition of GSH to the serum-free cultures of CHO cells markedly lowered the intracellular ROS level, which effect was comparable to that of the addition of serum (0.4, 10%) and might be due to the reduction of ROS. The addition of iron chelators, deferoxamine and aurintricarboxylic acid, to the serum-free cultures also decreased the intracellular ROS level and increased the residual concentration of viable cells during the serum-free maintenance culture, which should be due to the inhibition of the Fenton and Harber-Weiss reactions stimulating the synthesis of ROS. The combined addition of GSH and the chelators decreased ROS level and cell death more effectively compared with their single addition.     

Transduction of static pressure signal to expression of human granurocytes macrophage colony stimulating factor mRNA in Chinese hamster ovary cells

The expression level of human granurocytes macrophage colony stimulating factor (hGM-CSF) mRNA in Chinese hamster ovary (CHO) DR1000L4N cells increased by 24% with pressurization. Treatment of cells with chelerythrine chloride (10 nM, 15 min), an inhibitor of protein kinase C (PKC), did not suppress the pressure-induced (0.9 MPa) expression of hGM-CSF mRNA, while it decreased the hGM-CSF gene expression level at normal pressure (0.1 MPa). Treatment with U0126 (20 microM, 60 min), a specific inhibitor of extracellular signal-related kinase (ERK1/2), decreased the expression level of hGM-CSF mRNA at 0.1 MPa to 80% of that without U0126 treatment. Similarly, treatment with U0126 decreased the pressure-induced (0.9 MPa) expression level of hGM-CSF mRNA to 79% of the control expression level at 0.1 MPa without treatment. The amount of intracellular phosphorylated ERK1/2 increased with pressurization (0.9 MPa). These results suggest that the pressure-induced expression of hGM-CSF mRNA in CHO DR1000L4N cells depends not on PKC but on the ERK1/2 signaling cascade.     

Real Space Imaging of the Electronic States in Underdoped Ca2−x Na x CuO2Cl2 Single Crystals

Scanning tunneling microscopy (STM) has been performed on underdoped Ca_2–x Na _x CuO₂Cl₂ (Na-CCOC) single crystals to investigate the electronic states of doped Mott insulators near the metal-insulator transition. STM images taken at 7 K show patch-like or river-like irregular features superposed on the atomic corrugations. The irregular structure has a characteristic length scale of 20 Å, which is unchanged in different samples and at different doping levels studied (0.08<x<0.12). Bias voltage dependence of the STM image suggests that Na-CCOC consists of two distinct phases with different electronic states.     

Superconducting Gap Structure of YNi2B2C Determined by Thermal Conductivity

In order to determine the superconducting gap structure of the borocarbide superconductor YNi₂B₂C, we have measured the angular variation of the c-axis thermal conductivity _zz in magnetic field rotated within the ab-planes. A clear fourfold symmetry with narrow cusps was observed in the angular variation of _zz . These results provide a strong evidence that the gap function has point nodes which are located along the a- and b-axes of the crystal.     

Dietary CLA and DHA modify skin properties in mice

This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation.     

Preparation and characterization of the Sb-doped TiO2 photocatalysts

Doped TiO₂ photocatalysts have been prepared by a coprecipitation method. Uniformly doped nanocrystalline TiO₂ of 10–20 nm sizes was synthesized by calcinating the coprecipitated gels at 400–650°C. Photocatalytic characterization along with the microstructural investigation for each catalyst provides better understanding of the photocatalytic behavior. It was found that the photodegradation of methylene blue (MB) was a complex function of the doping type and its concentration and the microstructural characteristics of the catalysts. Antimony doing significantly improved photocatalytic performance as compared to the undoped TiO₂. Post-treatment of the as-precipitated wet doped Ti gels in an organic solvent also increased the surface area, forming approximately 8 nm size doped TiO₂ with surface area 149 m²/g. Superior catalytic activity was observed in the Sb-doped TiO₂ samples at a doping concentration ranging from 1 to 5 at%. Using the 5 at% Sb-doped TiO₂ catalyst treated in butanol, 100 ppm of MB could be decomposed completely within 1 h, which was better than the commercial Degussa P-25.