Ferroelectricity from iron valence ordering in the charge-frustrated system LuFe2O4

Ferroelectric materials are widely used in modern electric devices such as memory elements, filtering devices and high-performance insulators. Ferroelectric crystals have a spontaneous electric polarization arising from the coherent arrangement of electric dipoles (specifically, a polar displacement of anions and cations). First-principles calculations and electron density analysis of ferroelectric materials have revealed that the covalent bond between the anions and cations, or the orbital hybridization of electrons on both ions, plays a key role in establishing the dipolar arrangement. However, an alternative model-electronic ferroelectricity-has been proposed in which the electric dipole depends on electron correlations, rather than the covalency. This would offer the attractive possibility of ferroelectric materials that could be controlled by the charge, spin and orbital degrees of freedom of the electron. Here we report experimental evidence for ferroelectricity arising from electron correlations in the triangular mixed valence oxide, LuFe(2)O(4). Using resonant X-ray scattering measurements, we determine the ordering of the Fe(2+) and Fe(3+) ions. They form a superstructure that supports an electric polarization consisting of distributed electrons of polar symmetry. The polar ordering arises from the repulsive property of electrons-electron correlations-acting on a frustrated geometry.     

Radioprotective effect of reticuloendothelial system blockade in mice

Zusammenfassung Die i.v. Injektion von Kohlepartikeln an Mäusen, 24 h vor einer Bestrahlung mit 600 R, bietet einen bemerkenswerten Strahlenschutz. Die Problematik der biologischen Schutzfunktion durch die Reticulo-histiocytäre Systemblockade wird diskutiert.     

Periostin in vitreoretinal diseases

Proliferative vitreoretinal diseases such as diabetic retinopathy, proliferative vitreoretinopathy (PVR), and age-related macular degeneration are a leading cause of decreased vision and blindness in developed countries. In these diseases, retinal fibro(vascular) membrane (FVM) formation above and beneath the retina plays an important role. Gene expression profiling of human FVMs revealed significant upregulation of periostin. Subsequent analyses demonstrated increased periostin expression in the vitreous of patients with both proliferative diabetic retinopathy and PVR. Immunohistochemical analysis showed co-localization of periostin with α-SMA and M2 macrophage markers in FVMs. In vitro, periostin blockade inhibited migration and adhesion induced by PVR vitreous and transforming growth factor-β2 (TGF-β2). In vivo, a novel single-stranded RNAi agent targeting periostin showed the inhibitory effect on experimental retinal and choroidal FVM formation without affecting the viability of retinal cells. These results indicated that periostin is a pivotal molecule for FVM formation and a promising therapeutic target for these proliferative vitreoretinal diseases.     

Release of 3,5,3′-triiodothyronine,thyroxine and thyroglobulin from TSH-stimulated mouse thyroids in the perifusion system

Summary We established a perifusion system using mouse thyroid glands. In this system, TSH increased the release of T₃ and T₄ significantly, and the response of thyroglobulin to TSH was delayed in comparison with that of T₃ and T₄.     

Granulocytosis induced in vivo by a mouse marrow stromal cell line,BMA1, which produces colony stimulating factor

Summary Nude mice were inoculated with BMA1 cells. These are cells which produce granulocyte-macrophage colony stimulating factor (GM-CSF); They are derived from mouse bone marrow stromal cells transfected with adenovirus 5 DNA. Progressive neutrophilia developed as the tumor grew, but disappeared quickly after local tumor excision. Media conditioned with tumor cells had GM-CSF but neither erythropoietin, nor burst-promoting activity. In all the tumors which developed, focal areas of bone formation were found among fibrosarcomatous tissues.     

Development of new hypoxic cell sensitizers: Amides of nitrobenzoic acid with spermidine and spermine

Summary New type hypoxic cell sensitizers, N¹, N¹⁰-bis(4-nitrobenzoyl)spermidine (1) and N¹,N¹⁴-bis(4-nitrobenzoyl)-spermine (2), have been developed. These compounds were shown to be more effective radiosensitizers to hypoxic cells than misonidazole (3).     

Radioprotection of LPS-resistant C3H/HeJ mice by RES-blockade

Summary The radioprotective effect of RES-blockade was studied in LPS-resistant mice. Injection of carbon particles protected these mice from radiation lethality whereas LPS did not; thus a difference in the mechanism of radioprotection was demonstrated.This work was supported in part by Grants-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan.     

Effects of three synthetic peptides analogous to neurohypophyseal hormones on the excitability of giant neurones ofAchatina fulica Férussac

Summary Deamino-dicarba-(d-d-)oxytocin andd-d-Arg-vasotocin at 10^–4 kg/l showed an excitatory effect on the periodically oxcillating neurone (PON) ofAchatina fulica Férussac.d-d-Arg-vasopressin had no effect.