Biologic characteristics of cultured human vitiligo melanocytes

BACKGROUND: Vitiligo is a pigmentary disorder of unknown cause characterized by depigmented patches due to destruction of melanocytes. Recently, the inherent cellular defect theory has been discussed. To investigate the biologic characteristics of cultured melanocytes from normal and vitiligo subjects, this study had the purpose to examine the functional and ultrastructural characteristics of these melanocytes and to observe the morphologic and functional changes of melanocytes in response to ultraviolet B irradiation. METHODS: Melanocytes were isolated and cultured from foreskin and arm skin of normal and vitiligo subjects. The DNA synthesis, tyrosinase activity assay, transmission and scanning electron microscopic examination, and the effects of ultraviolet B(UVB)-irradiation on cultured melanocytes were studied. RESULTS: Vitiligo melanocytes showed no significant differences in DNA synthesis and tyrosinase activity compared with normal melanocytes, but the vitiligo melanocytes contained dilated and/or circular rough endoplasmic reticulum (RER) on transmission electron microscopic examination. Exposure of the cultured melanocytes to UVB resulted in increased protein synthesis and tyrosinase activity. Morphologic alterations and changes in DNA synthesis were also noted. Compared with normal melanocytes, the responses of vitiligo melanocyte to UVB showed no significant difference. CONCLUSIONS: Normal and vitiligo melanocytes showed similar biologic characteristics except in the changes of RERs in the vitiligo melanocytes. The ultrastructural aberrations in vitiligo subjects do not seem to be directly related to the biologic characteristics and the responses to UVB irradiation in vitiligo melanocytes.     

Constituents isolated from Glehnia littoralis suppress proliferations of human cancer cells and MMP expression in HT1080 cells

Crude extract and solvent-partitioned fraction of Glehnia littoralis were found to possess different anti-proliferative effects against AGS, HT1080 and U937 human cancer cells. The crude extracts and solvent fractions dose-dependently inhibited cell proliferation. Especially, n-hexane and 85% aqueous MeOH fractions exhibited comparatively higher anti-proliferative effects and reduced expressions of Bcl-2, COX-2 and iNOS genes. Systematic separation of all solvent fractions by chromatographic methods led to the isolation of three glucopyranosides, four furanocoumarins and two polyacetylenic alcohols. All the nine compounds were evaluated for their inhibitory effects against both proliferation of human cancer cells and expressions of MMP-2 and -9 in HT1080 cells. Two polyacetylenic alcohols exerted the highest inhibitory activity against both human cancer cell lines, and MMP-2 and -9. These results suggest that G. littoralis may possibly be used as a valuable chemopreventive agent or food supplement for reducing cancer risk.     

Cyclic delay diversity with frequency domain turbo equalization for uplink fast fading channels

Cyclic delay diversity (CDD) is an attractive diversity technique due to its low complexity and compatibility to existing wireless communication systems. This letter proposes a CDD with frequency domain turbo equalization (FDTE) for single carrier (SC) transmission, in order to achieve the full spatial diversity of frequency-selective multi-antenna channels. The frequency diversity inherent in SC is picked up from the increased channel selectivity of CDD. The noise or intersymbol interference enhanced by equalization for highly selective channels is then mitigated through applying FDTE at the receiver. Simulation results show that the performance of proposed system approaches the corresponding orthogonal spacetime block coding (STBC) system in slowly fading channels without any data rate loss, and considerably outperforms the STBC system in fast fading channels.     

Fabrication of Ordered Nanostructured Arrays Using Poly(dimethylsiloxane) Replica Molds Based on Three‐Dimensional Colloidal Crystals

Hexagonally arrayed structures of colloidal crystals with uniform surface are a good candidate for master molds to be used in soft lithography. Here, the fabrication of periodically arrayed nanostructures using poly(dimethylsiloxane) (PDMS) molds based on three‐dimensionally (3D) ordered colloidal crystals is reported. A robust, high‐quality 3D colloidal‐crystal master molds is prepared using the colloidal suspension containing a water‐soluble polymer. The surface patterns of the 3D colloidal crystals can then be transferred onto a polymer film via soft lithography, by means of the replication of the surface pattern with PDMS. Various hexagonally arrayed nanostructure patterns can be fabricated, including close‐packed and non‐close‐packed 2D arrays and honeycomb structures by the structural modification of the 3D colloidal‐crystal templates. The replicated hexagonally arrayed structures can also be used as templates for producing colloidal crystals with 2D superlattices.     

Surface Modification of Exfoliated Layered Gadolinium Hydroxide for the Development of Multimodal Contrast Agents for MRI and Fluorescence Imaging

A novel method for modifying the surface of magnetic‐resonance‐contrasting layered gadolinium hydroxide (LGdH) is developed providing them with water‐ and bio‐compatibility and acid‐resistance, all of which are essential for medical applications. A stable colloid of exfoliated layers is synthesized by exchanging interlayer anions of LGdH with oleate ions. The delaminated layers are successively coated with phospholipids with poly(ethylene glycol) tail groups, and their effectiveness as a contrast agent for magnetic resonance imaging (MRI) is demonstrated. The adaptability of this surface modification approach for incorporating functional molecules and fabricating a fluorescent colloid of LGdH, which has the potential utility as a multimodal probe, is also demonstrated. This result provides a novel approach for expanding the applications of layered inorganic materials and developing a new class of MRI contrast agents.     

Preparation and characterization of proton conducting polysulfone grafted poly(styrene sulfonic acid) polyelectrolyte membranes

The syntheses of series of proton conducting comb copolymer membrane involving polysulfone back bone as main chain and poly(styrene sulfonic acid) (PSSA) being side chain, i.e. polysulfone grafted poly(styrene sulfonic acid) (PSU-g-PSSA) are presented. Chloromethylation of the polysulfone backbone was done by Fridel Craft alkylation reaction. Atom transfer radical polymerization was used for control grafting from the chloromethylated positions. The successful substitution of the chloromethyl group and its grafting with PSSA was characterized by elemental analysis and proton nuclear magnetic resonance. Water uptake, electrochemical properties like ion exchange capacity (IEC) and proton conductivities increase with increase in PSSA contents. Thermal gravimetric analysis (TGA) showed the thermal stability of membranes up to 250 °C. Proton conductivity for maximum amount of grafting is 0.02 S/cm.     

Synthesis and characterization of poly(ether sulfone) grafted poly(styrene sulfonic acid) for proton conducting membranes

Two-step synthesis of proton-conducting poly(ether sulfone) (PES) graft copolymer electrolyte membrane is proposed. Fridel Craft alkylation reaction was used to introduce chloromethyl pendant group onto the PES polymer backbone. Later on, atom transfer radical polymerization (ATRP) was applied to synthesize a series of poly(ether sulfone) grafted poly(styrene sulfonic acid) (PES-g-PSSA). Successful chloromethyl substitution and grafting of the pendant group was characterized by the ¹H-NMR and elemental analysis. Electrochemical properties such as ion exchange capacity (IEC), water uptake and proton conductivity increased with increasing PSSA contents. Thermal gravimetric analysis (TGA) showed the thermal stability of membranes up to 270 °C. Proton conductivity for maximum amount of grafting was 0.00297 S/cm.     

Novel immobilization of titanium dioxide (TiO2) on the fluidizing carrier and its application to the degradation of azo-dye

A photocatalyst was prepared by attaching TiO(2) powder (diameter, 50nm) in the sol state to fluidizing spherical ceramic carriers using a silicon binder. A high initial photocatalytic activity and strong attachment was obtained at a sintering temperature of 500 degrees C. An azo-dye (Orange-G) was used as the test contaminant to examine the photocatalytic effect of the new photocatalyst. The initial pseudo-first order degradation rate constant for Orange-G was 0.11min(-1). However, the photocatalytic activity doubled when boric acid was added to the silicon binder at a B to Si ratio of 106.5%. When sodium ethoxide was added to the silicon binder at a sodium ion to Si ratio of 15.0%, as much as 80% of the initial photocatalytic activity was maintained after the photocatalyst had been agitated at 180rpm for 300min. Adding both boric acid at a B/Si ratio of 106.5% and sodium ethoxide at a Na/Si ratio of 15% increased the photocatalytic activity and stability by three and four times, respectively.     

Material property variations and defects of carbon/carbon brake disks monitored by ultrasonic methods

Several ultrasonic techniques were applied to carbon/carbon brake disks for the evaluation of spatial variations in material properties that are attributable to the manufacturing process. In a carbon/carbon brake disk manufactured by a combination of pitch impregnation and vapor infiltration methods, the spatial variation of ultrasonic velocity was measured and found to be consistent with the nonuniform densification behavior in the manufacturing process. Low frequency (e.g. 1–5 MHz) through-transmission scans were used for mapping out the material property inhomogeneity. These results were compared with that obtained by dry-coupling ultrasonics. A good correlation was found between ultrasonic velocity and material density on a set of small blocks cut out of the disk. Pulse-echo C-Scans (10–25 MHz) were used to image near-surface material property anomalies associated with certain steps in the manufacturing process. Ultrasonic velocities in the in-plane directions were affected more by the relative contents of fabric and chopped fiber, and less by the void content.     

ZnO-Based Low-Voltage Inverter With Quantum-Well-Structured Nanohybrid Dielectric

We report on the fabrication of 2-V-operating ZnO-based inverter with two n-channel thin-film transistors (TFTs) on 22-nm-thin organic/inorganic nanohybrid dielectric, which contains AlO_x/TiO_x/AlO_x in triple-layer structure. The inverter shows a high voltage gain of ~20 under the supply voltage (V_DD) of 2 V but with a marginal transition voltage of 0.1 V (operation range of 0-2 V). To control the transition voltage to a more adequate value, an 8-V gate pulse was applied on driving ZnO-TFT so that some of the channel electrons would be tunneled through the AlO_x-based barrier and trapped in the TiO_x-based layer. Our inverter then displayed an optimum transition voltage of 0.75 V.