Interplay between Structure and Electronic Properties in Organic Conductors

It is known that the ground states of organic conductors have a diversity reflecting the spatial arrangement of the constituent molecules within the unit cell. A systematic theoretical search for the unifying view behind such possible ground states has been made based on the Hartree-Fock mean field approximation not only to the on-site but also to intersite Coulomb interactions with special emphasis on the families of typical organic conductors (TMTCF)$_2X$ and (ET)$_2X$.Comment: 6 pages, 3 figures, proceedings of LT22 (Helsinki, Finland, August 4-11, 1999

Ambipolar Organic Field-Effect Transistors Based on Indigo Derivatives

In order to improve the ambipolar performance of indigo-based semiconductors, we have investigated halogen-substituted (1 - 4) and phenyl-substituted (5) indigo derivatives at the 5-position. We show that introduction of iodine atoms, namely 5,5'-diiodoindigo (4), leads to the strong halogen-halogen interaction (iodine-iodine interaction) that gives a significant effect on the molecular packing. Thanks to the supramolecular network coming from the extra iodine-iodine interaction, the molecules are arranged approximately perpendicular to the substrate in the thin film. This results in remarkable transistor performance of the maximum hole and electron mobilities (µh/µe) = 0.42/0.85 cm2V–1s–1, which are one of the highest among small-molecule ambipolar organic transistors. Furthermore, introducing phenyl groups, 5 improves the transistor performances up to the maximum mobilities µh/µe = 0.56/0.95 cm2V–1s–1. We have found that the phenyl groups destroy the standard molecular packing of indigo to achieve a unique structure that is a hybrid of the herringbone and brickwork structures

Membrane-Type 1 Matrix Metalloproteinase Cleaves Cd44 and Promotes Cell Migration

Migratory cells including invasive tumor cells frequently express CD44, a major receptor for hyaluronan and membrane-type 1 matrix metalloproteinase (MT1-MMP) that degrades extracellular matrix at the pericellular region. In this study, we demonstrate that MT1-MMP acts as a processing enzyme for CD44H, releasing it into the medium as a soluble 70-kD fragment. Furthermore, this processing event stimulates cell motility; however, expression of either CD44H or MT1-MMP alone did not stimulate cell motility. Coexpression of MT1-MMP and mutant CD44H lacking the MT1-MMP–processing site did not result in shedding and did not promote cell migration, suggesting that the processing of CD44H by MT1-MMP is critical in the migratory stimulation. Moreover, expression of the mutant CD44H inhibited the cell migration promoted by CD44H and MT1-MMP in a dominant-negative manner. The pancreatic tumor cell line, MIA PaCa-2, was found to shed the 70-kD CD44H fragment in a MT1-MMP–dependent manner. Expression of the mutant CD44H in the cells as well as MMP inhibitor treatment effectively inhibited the migration, suggesting that MIA PaCa-2 cells indeed use the CD44H and MT1-MMP as migratory devices. These findings revealed a novel interaction of the two molecules that have each been implicated in tumor cell migration and invasion

The metastasis-promoting protein S100A4 regulates mammary branching morphogenesis

AbstractHigh levels of the S100 calcium binding protein S100A4 also called fibroblast specific protein 1 (FSP1) have been established as an inducer of metastasis and indicator of poor prognosis in breast cancer. The mechanism by which S100A4 leads to increased cancer aggressiveness has yet to be established; moreover, the function of this protein in normal mammary gland biology has not been investigated. To address the role of S100A4 in normal mammary gland, its spatial and temporal expression patterns and possible function in branching morphogenesis were investigated. We show that the protein is expressed mainly in cells of the stromal compartment of adult humans, and during active ductal development, in pregnancy and in involution of mouse mammary gland. In 3D culture models, topical addition of S100A4 induced a significant increase in the TGFα mediated branching phenotype and a concomitant increase in expression of a previously identified branching morphogen, metalloproteinase-3 (MMP-3). These events were found to be dependent on MEK activation. Downregulation of S100A4 using shRNA significantly reduced TGFα induced branching and altered E-cadherin localization. These findings provide evidence that S100A4 is developmentally regulated and that it plays a functional role in mammary gland development, in concert with TGFα by activating MMP-3, and increasing invasion into the fat pad during branching. We suggest that S100A4-mediated effects during branching morphogenesis provide a plausible mechanism for how it may function in breast cancer progression

Low X-ray Efficiency of a Young High-B Pulsar PSR J1208-6238 Observed with Chandra

High magnetic field (high-B) pulsars are key sources to bridge magnetars and conventional rotation powered pulsars, and thus to understand the origin of magnetar activities. We have estimated a tight upper-limit on the X-ray flux of one of the youngest high-B pulsars PSR J1208-6238 for the first time; a Chandra 10 ks observation shows no significant source. Depending on the emission models, the 3sigma upper-limit on the intrinsic 0.5-7 keV flux to (2.2-10.0)e-14 erg/s/cm2.Comment: 7 pages, 6 figures, Ap&SS, accepte

A four-dimensional organoid system to visualize cancer cell vascular invasion

Yanagisawa, K.; Konno, M.; Liu, H.; Irie, S.; Mizushima, T.; Mori, M.; Doki, Y.; Eguchi, H.; Matsusaki, M.; Ishii, H. A Four-Dimensional Organoid System to Visualize Cancer Cell Vascular Invasion. Biology 2020, 9, 361

Ca2+-permeable mechanosensitive channels MCA1 and MCA2 mediate cold-induced cytosolic Ca2+ increase and cold tolerance in Arabidopsis

Cold shock triggers an immediate rise in the cytosolic free calcium concentration ([Ca2+]cyt) in Arabidopsis thaliana and this cold-induced elevation of [Ca2+]cyt is inhibited by lanthanum or EGTA. It is suggested that intracellular calcium mainly contributes to the cold-induced [Ca2+]cyt response by entering into the cytosol. Two calcium-permeable mechanosensitive channels, MCA1 and MCA2 (mid1-complementing activity), have been identified in Arabidopsis. Here, we demonstrate that MCA1 and MCA2 are involved in a cold-induced increase in [Ca2+]cyt. The cold-induced [Ca2+]cyt increase in mca1 and mca2 mutants was markedly lower than that in wild types. The mca1 mca2 double mutant exhibited chilling and freezing sensitivity, compared to wild-type plants. Expression of At5g61820, At3g51660, and At4g15490, which are not regulated by the CBF/DREB1s transcription factor, was down-regulated in mca1 mca2. These results suggest that MCA1 and MCA2 are involved in the cold-induced elevation of [Ca2+]cyt, cold tolerance, and CBF/DREB1-independent cold signaling

Anticancer drug sensitivity by human tumor clonogenic assay.

The anticancer drug sensitivity of human cancers was tested by the human tumor clonogenic assay (HTCA). Of 152 human cancer specimens tested, 63 (41%) formed more than 30 tumor cell colonies in control plates and could be used to evaluate the drug sensitivity of tumor cells. In 42 (93%) of 45 clinical trials in 24 patients, a parallel correlation was observed between the in vitro anticancer drug sensitivity measured by the HTCA and the clinical response of tumors to anticancer drugs. These results suggest that the HTCA is a good technique for the in vitro test of the anticancer drug sensitivity of human cancers.</p