Characterization of Secretory Phospholipase A<Subscript>2</Subscript> with Phospholipase A<Subscript>1</Subscript> Activity in Tobacco, <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> (L.)

A cDNA encoding protein with homology to plant secretory phospholipase A₂ (sPLA₂), denoted as Nt1 PLA₂, was isolated from tobacco (Nicotiana tabacum). The cDNA encodes a mature protein of 118 amino acid residues with a putative signal peptide of 29 residues. The mature form of Nt1 PLA₂ has 12 cysteines, Ca²⁺ binding loop and catalytic site domain that are commonly conserved in plant sPLA₂s. The recombinant Nt1 PLA₂ was expressed as a fusion protein with thioredoxin in E. coli BL21 cells and was purified by an ion exchange chromatography after digestion of the fusion proteins by Factor Xa protease to obtain the mature form. Interestingly, Nt1 PLA₂ could hydrolyze the ester bond at the sn-1 position of glycerophospholipids as well as at the sn-2 position, when the activities were determined using mixed-micellar phospholipids with sodium cholate. Both activities for the sn-1 and -2 positions of glycerophospholipids required Ca²⁺ essentially, and maximal activities were found in an alkaline region when phosphatidylcholine, phosphatidylglycerol or phosphatidylethanolamine was used as a substrate. The level of Nt1 PLA₂ mRNA was detected at a higher level in tobacco flowers than stem, leaves and roots, and was induced by salicylic acid.     

Influence of film structure on gas barrier properties of SiOxNy films

SiO_xN_y thin films were deposited on PET substrates by dc magnetron sputtering under various nitrogen gas flow ratios, and the influence of the nitrogen gas flow ratio on the gas barrier performance was examined on the basis of local structure of SiO_xN_y. The surface morphology of the films was evaluated by FE-SEM and AFM observations. The local structure of SiO_xN_y was determined by FT-IR analysis and measurement of refractive index. No obvious macro-defects, such as pinholes, were observed in the films and the surface morphology of all samples was similar. The film density increased with increasing nitrogen gas flow ratio during the deposition process. However, the gas barrier performance decreased with increasing nitrogen gas flow ratio. On the basis of FT-IR analysis, it was determined that the structure of the SiO_xN_y film was a random bonding model (RBM) structure and an increase in the nitrogen gas flow ratio caused an increase in hydrogen termination in the Si-O-N network. The degradation of gas barrier performance at a high nitrogen gas flow ratio is due to the discontinuous Si-O-N network caused by the hydrogen termination.     

The novel functional nucleic acid iRed effectively regulates target genes following cytoplasmic delivery by faint electric treatment

An intelligent shRNA expression device (iRed) contains the minimum essential components needed for shRNA production in cells, and could be a novel tool to regulate target genes. However, general delivery carriers consisting of cationic polymers/lipids could impede function of a newly generated shRNA via electrostatic interaction in the cytoplasm. Recently, we found that faint electric treatment (fET) of cells enhanced delivery of siRNA and functional nucleic acids into the cytoplasm in the absence of delivery carriers. Here, we examined fET of cells stably expressing luciferase in the presence of iRed encoding anti-luciferase shRNA. Transfection of lipofectamine 2000 (LFN)/iRed lipoplexes showed an RNAi effect, but fET-mediated iRed transfection did not, likely because of the endosomal localization of iRed after delivery. However, fET in the presence of lysosomotropic agent chloroquine significantly improved the RNAi effect of iRed/fET to levels that were higher than those for the LFN/iRed lipoplexes. Furthermore, the amount of lipid droplets in adipocytes significantly decreased following fET with iRed against resistin in the presence of chloroquine. Thus, iRed could be a useful tool to regulate target genes following fET-mediated cytoplasmic delivery with endosomal escape devices.     

Analysis of reflector antenna system including frequency selectivesurfaces

Frequency selective surfaces (FSS) are often used in spaceborne applications of reflector antennas because of their ability to allow multiple feeds to utilize the same reflector dish. The problems inherent in evaluating the FSS separately from the reflector system are discussed. A method of integrating the FSS effects into the reflector system analysis is presented. An example is given for the proposed Advanced Tracking and Delay Relay Satellite System (ATDRSS) single-access triband reflector antenna     

A PWM rectifier/inverter system capable of suppressing both harmonics and EMI

This paper proposes a new PWM rectifier/inverter system that is capable of suppressing not only supply harmonic currents but also electromagnetic interference (EMI). The conversion system consists of a PWM rectifier and inverter, and an active common‐noise canceler (ACC) which has been proposed by the authors. The ACC developed for this system is characterized by the sophisticated connection of a common mode transformer which can compensate for common mode voltages produced by both the PWM rectifier and inverter. As a result, the size of the common mode transformer can be reduced to one‐third, compared with the previously proposed ACC. A prototype PWM rectifier/inverter system (2.2 kW) has been implemented and tested. Some experimental results show reduction characteristics of the supply harmonic current and EMI. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 59–68, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10062     

Human monoclonal rheumatoid factors augment arthritis in mice by the activation of T cells

In order to investigate the in vivo role of rheumatoid factor (RF), the effects of the administration of human monoclonal (m) IgM-RF and IgG-RF on the development of arthritis in mice were examined. The administration of human mRFs into mice immunized with type II collagen (CII) markedly enhanced the clinical score and paw swelling. The severity of arthritic joint disease with a marked infiltration of lymphoid cells, proliferation of synovial membrane, pannus formation and destruction of articular cartilage was significantly enhanced in both groups receiving RF (RF-enhanced arthritis). Skin ulcers were also observed in some of these RF-enhanced arthritis mice, whereas no such signs were observed in CII-immunized mice without mRFs. Both IgM-RF and IgG-RF increased CII-specific IgG antibodies in circulation, and the severity of arthritis correlated with the production of high titres of anti-CII antibodies. In vivo treatment of RF-enhanced arthritis mice with an anti-CD4 MoAb or an anti-CD8 MoAb inhibited the induction and progression of arthritis in these mice. Administration of RF to severe combined immunodeficient (SCID) mice with arthritis developed by the transfer of spleen cells from CII-immunized mice, prolonged the arthritis and enhanced the severity. This murine model of RF-enhanced arthritis may provide a useful tool for analysing the pathogenesis of rheumatoid arthritis in RF-positive patients.     

Effect of defects and moisture on insulation characteristics of XLPE insulated cable

Sample cables having a few types of defects (such as voids, contaminants, and protrusions) with more volume than usual, were prepared intentionally to clarify how these defects affect separately insulation characteristics under the presence/nonpresence of moisture. In the case of void inclusion, insulation characteristics are even more susceptible to ac voltage than impulse voltage, and the distribution of lifetimes is classified into a wornout failure type due to discharge deterioration. While protrusions and some other contaminants can greatly deteriorate original dielectric strength, these defects have a relatively slight effect on long-term endurance in the atmosphere. Therefore, the distribution of lifetimes is classified into an early-failure type. With reference to the influence of moisture, in a strong electric field (exceeding 15 kV/mm) and in a short-term region, there is an increase in harmfulness around defects with water absorbed, thereby inducing electrical trees and resulting in a breakdown. In the light electric field (no more than 15 kV/mm) and in a long-term region, harmfulness of defects will not deepen to a considerable extent, and the growth of water trees very possibly is influential.     

Effect of the Manganese Valence State on the Electrical Conductivity of Barium Titanate

The effect of defect structure on electrical conductivity for Mn-doped BaTiO₃ at high temperatures was studied experimentally and theoretically. The measured conductivity was proportional to P_o2^−1/4 in the n -type region, and to P _o2^+1/6 in the p -type region in the temperature range between 900° and 1000°C. The results agree with calculations on the basis of the equilibrium equation for the valence change of Mn ions between tetravalent and trivalent. In the p -type region, the concentration of trivalent Mn ions decreases with P _o2^−1/6.