University of Tsukuba

About: University of Tsukuba is a education organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Population & Gene. The organization has 36352 authors who have published 79483 publications receiving 1934752 citations. The organization is also known as: Tsukuba daigaku & Tsukuba University.

Crystal structure and ferroelectric properties of A Bi 2 Ta 2 O 9 ( A = Ca , Sr, and Ba)

Abstract: Crystal structures and ferroelectric properties of a series of Bi-layered compounds, ${\mathrm{CaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9},$ ${\mathrm{SrBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9},$ and ${\mathrm{BaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9},$ were investigated. The structures of ${\mathrm{CaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9}$ and ${\mathrm{SrBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9}$ are orthorhombic, while that of ${\mathrm{BaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9}$ is pseudotetragonal on the macroscopic scale but consists of microdomains with orthorhombic distortion. The ferroelectric Curie temperature of ${\mathrm{CaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9}$ was over 600 \ifmmode^\circ\else\textdegree\fi{}C, and that of ${\mathrm{SrBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9}$ was over 300 \ifmmode^\circ\else\textdegree\fi{}C. ${\mathrm{BaBi}}_{2}{\mathrm{Ta}}_{2}{\mathrm{O}}_{9},$ in contrast, showed relaxor-type ferroelectric behavior; that is, in the plot of temperature dependence of dielectric constant, a broad peak appeared around 60 \ifmmode^\circ\else\textdegree\fi{}C. As the size of the A-site cation decreases from ${\mathrm{Ba}}^{2+}$ to ${\mathrm{Ca}}^{2+},$ the lattice mismatch between ${\mathrm{TaO}}_{2}$ and $A\mathrm{O}$ planes in the perovskite-type unit of $A{\mathrm{Ta}}_{2}{\mathrm{O}}_{7}$ increases and the structural distortion becomes more pronounced. This distortion leads to the higher Curie temperature and the larger spontaneous ferroelectric polarization.

Troglitazone Inhibits Atherosclerosis in Apolipoprotein E–Knockout Mice: Pleiotropic Effects on CD36 Expression and HDL

Abstract: —Atherosclerotic coronary heart disease is a common complication of the insulin resistance syndrome that can occur with or without diabetes mellitus. Thiazolidinediones (TZDs), which are insulin-sensitizing antidiabetic agents, can modulate the development of atherosclerosis not only by changing the systemic metabolic conditions associated with insulin resistance but also by exerting direct effects on vascular wall cells that express peroxisome proliferator–activated receptor-γ (PPAR-γ), a nuclear receptor for TZDs. Here we show that troglitazone, a TZD, significantly inhibited fatty streak lesion formation in apolipoprotein E–knockout mice fed a high-fat diet (en face aortic surface lesion areas were 6.9±2.5% vs 12.7±4.7%, P<0.05; cross-sectional lesion areas were 191 974±102 911 μm2 vs 351 738±175 597 μm2, P<0.05; n=10). Troglitazone attenuated hyperinsulinemic hyperglycemia and increased high density lipoprotein cholesterol levels. In the aorta, troglitazone markedly increased the mRNA levels o...

Distinct roles of the co-activators p300 and CBP in retinoic-acid-induced F9-cell differentiation.

Abstract: The related proteins p300 and CBP (cAMP-response-element-binding protein (CREB)-binding protein)) are transcriptional co-activators that act with other factors to regulate gene expression and play roles in many cell-differentiation and signal transduction pathways Both proteins have intrinsic histone-acetyltransferase activity and may act directly on chromatin, of which histone is a component, to facilitate transcription They are also involved in growth control pathways, as shown by their interaction with the tumour suppressor p53 and the viral oncogenes E1A and SV40 T antigen Here we report functional differences of p300 and CBP in vivo We examined their roles during retinoic-acid-induced differentiation, cell-cycle exit and programmed cell death (apoptosis) of embryonal carcinoma F9 cells, using hammerhead ribozymes capable of cleaving either p300 or CBP messenger RNAs F9 cells expressing a p300-specific ribozyme became resistant to retinoic-acid-induced differentiation, whereas cells expressing a CBP-specific ribozyme were unaffected Similarly, retinoic-acid-induced transcriptional upregulation of the cell-cycle inhibitor p21Cip1 required normal levels of p300, but not CBP, whereas the reverse was true for p27Kip1 In contrast, both ribozymes blocked retinoic-acid-induced apoptosis, indicating that both co-activators are required for this process Thus, despite their similarities, p300 and CBP have distinct functions during retinoic-acid-induced differentiation of F9 cells

Polyamines and their ability to provide environmental stress tolerance to plants

Abstract: The present review highlights some recent advances regarding the function of polyamines in the environmental stress tolerance of plants. When exposed to adverse environmental stresses, such as salt, drought, low temperature, and ozone, the complex dynamic kinetics of polyamine biosynthesis was observed. Polyamines titers altered in different manners dependent upon several factors, such as plant species, tolerance or sensitivity to stress, and duration of stress. The exogenous addition of polyamines to stress-treated cells or tissues could lead to injury alleviation and growth promotion in most cases, although the effects varied between polyamines and among plant species. Key genes responsible for polyamine biosynthesis have been cloned from a variety of plant species, whose expressions following stress have been investigated on a molecular basis. Overexpression of the genes caused the modification of polyamine biosynthesis in the transformants coupled with enhancement of stress tolerance. All of these results seem to indicate that polyamines are an important component in a plant's response to stress and that they play a significant role in counteracting stress.