Integrin α7 and extracellular matrix Laminin 211 interaction promotes proliferation of acute myeloid leukemia cells and is associated with granulocytic sarcoma

学位記番号：医博甲174

Quantitation and Visualization of Ultraviolet Induced DNA Damage Using Specific Antibodies

The major types of DNA damage induced by sunlight in the skin are DNA photoproducts, such as cyclobutane pyrimidine dimers (CPDs), (6-4)photoproducts (6-4PPs) and Dewar isomers of 6-4PPs. A sensitive method for quantitating and visualizing each type of DNA photoproduct induced by biologically relevant doses of UV or sunlight is essential to characterize DNA photoproducts and their biologlcal effects. We have established monoclonal antibodies specific for CPDs, 6-4PPs or Dewar isomers. Those antibodies allow one to quantitate photoproducts in DNA purified from cultured cells or from the skin epidermis uslng an enzyme-linked immunosorbent assay. One can also use those specific antibodies with in situ laser cytometry to visualize and measure DNA photoproducts in cultured cells or in the skin, using indirect immunofluorescence and a laser-scannlng confocal microscope. This latter method allows us to reconstruct three-dimensional images of nuclei containlng DNA photoproducts, and to simultaneously examine DNA photoproducts and histology in multilayered epidermis. Using those techniques, one can determine the induction and repair of these three distinct types of DNA photoproducts in cultured cells and in the skin exposed to sublethal or suberythematous doses of UV or solar simulated radiation. As examples of the utility of these techniques and antibodies, we describe the DNA repalr kinetics followlng irradiation of human cell nuclei and the photoprotective effect of melanin against DNA photoproducts in cultured pigrlented cells and in human epidermis

A Computational Phase Field Study of Conducting Channel Formation in Dielectric Thin Films: A View Towards the Physical Origins of Resistive Switching

A phase field method is used to computationally study conducting channel morphology of resistive switching thin film structures. Our approach successfully predicts the formation of conducting channels in typical dielectric thin film structures, comparable to a range of resistive switches, offering an alternative computational formulation based on metastable states treated at the atomic scale. In contrast to previous resistive switching thin film models, our formulation makes no a priori assumptions on conducting channel morphology and its fundamental transport mechanisms

An electro-thermal computational study of conducting channels in dielectric thin films using self-consistent phase-field methodology: A view toward the physical origins of resistive switching

A large number of experimental studies suggest two-terminal resistive switching devices made of a dielectric thin film sandwiched by a pair of electrodes exhibit reversible multi-state switching behaviors; however coherent understanding of physical and chemical origins of their electrical properties needs to be further pursued to improve and customize the performance. In this paper, phase-field methodology is used to study the formation and annihilation of conductive channels resulting in reversible resistive switching behaviors that can generally occur in any dielectric thin films. Our focus is on the dynamical evolution of domains made of electrical charges under the influence of spatially varying electric field and temperature resulting in distinctive changes in electrical conductance.Comment: 6 pages, 5 figure

On the Phononic Bandgap of Carbon Nanotubes

On the phononic bandgap of carbon nanotubes (CNTs), we show in what chirality CNTs have phononic bandgaps and its dependence on the diameters of CNTs. We find that, though the rule where CNTs have phononic bandgaps is the same as in the electronic structure case, the diameter dependence is different. The phononic bandgaps of the zigzag-CNTs reveal “three” kinds of diameter dependence due to the anisotropy of graphene phonon band around the K point in k-space. We also show the crossover from one- to two-dimensional characteristics in phononic bandgaps

Melanin Reduces Ultraviolet-Induced DNA Damage Formation and Killing Rate in Cultured Human Melanoma Cells

Epidermal melanin pigment is believed to prevent development of ultraviolet (UV)–induced skin cancer by shielding cell nuclei and reducing DNA damage formation. It has not been experimentally proved, however, whether melanin reduces UV-induced DNA damage, because published experiments have been inconclusive. The present study was carried out to determine whether intracellular melanin protected cultured cells against UV-induced DNA damage and killing. Three human melanoma cell lines containing different amounts of melanin were used. Absorption spectrum, subcellular localization of melanin, and melanin concentration were examined in the three cell lines. Two types of DNA damages cyclobutane pyrimidine dimers and (6-4)photoproducts, were detected by an enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies specific for these photolesions. We found that melanin reduced the induction rates of both types of DNA damage in pigmented cells irradiated with low doses of UV in a melanin concentration-dependent manner. Almost no differences in repair capacity for the two types of photolesions were observed among the three melanoma cell lines. We also found that the more highly melanotic melanoma cell lines were more UV resistant than the less melanotic melanoma cell lines. These results suggest that intracellular melanin plays an important role in preventing UV-induced cell killing by reducing the formation of two types of DNA damage