bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical simulations on beam and/or null forming performance of ESPAR antennas
Authors: Akiyama Akira , Gyoda Koichi , Ohira Takashi , Ando Makoto
Published: June 2003

The radiation pattern of the ESPAR antenna is controlled by variable reactances loaded to its passive elements. In this paper, the effects of the number of elements and the variable range of the reactance value on the beam and null forming capability are studied by simulation using the method of moments. It is found that a beam with a directivity of more than 8 dBi and a null of less than −40 dBi can be scanned independently in all directions when the number of elements is more than 5 and the reactance value range is ±50 Ω. The reactance range of ±50 Ω is needed for simultaneous forming of a single beam of more than 5 dBi and a single null of less than −30 dBi, while ± 100 Ω is needed for simultaneous forming of a single beam of more than 5 dBi and multiple nulls of less than −15 dBi. The direction of the beam and null can be close as the number of elements is increased. The input impedance of the feed element is also studied and the standard return loss of a seven‐element antenna is found to be 15.8 dBi. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(12): 1–11, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10141
Cellular search performance of a W‐CDMA cellular system using diversity
Authors: Imai Tetsuro , Mori Shinichi
Published: June 2003

Broadband DS‐CDMA (W‐CDMA) has been adopted as the wireless access scheme for the next‐generation mobile communication system IMT‐2000. Since the scheme is asynchronous between base stations, there must be functions for discrimination and synchronization timing detection of the spreading code (scrambling code). The three‐step cell search method is proposed as its realization. Various diversity methods have been used in mobile communication in order to improve communications quality. Performance improvement is also expected from the proposed scheme with the use of diversity. This paper considers the case in which (1) the transmit diversity (TSTD) and (2) the receiving antenna diversity are used in the three‐step cell search method. The performance is analyzed and the effectiveness of each diversity is investigated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(12): 91–104, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1182
A study on multilevel decision feedback viterbi equalizer to (1,7) code at the optical disk recorder
Authors: Itoi Satoshi
Published: June 2003

We examined an algorithm for a multilevel adaptive decision feedback (DF) Viterbi equalizer that combines PR(1,1), PR(1,2,1), PR(2,3,2), or PR(1,2,2,1) preequalization, RAM‐DFE (Decision Feedback Equalizer), and Viterbi decoding with the (1,7) code as an ideal recording code and equalization detection scheme in optical disk recorders and evaluated its performance by simulations. The results showed that the minimum bit length of 0.24 µm could be realized in current recording and playback systems by applying PR(1,2,2,1) and 7‐level decision feedback Viterbi equalization. We also verified that the proposed equalization decision scheme is also suited to recorded codes that are not DC free in order to improve the error rate reduction when a DC offset is generated and is effective in shortening the convergence time at low bit rates due to the fast recovery speed from burst errors. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 51–63, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10087
The effects of laser annealing ambient and the number of laser shots on the morphology of poly‐si films
Authors: Suga Katsuyuki , Chida Mitsuru , Hara Akito , Mishima Yasuyoshi , Sasaki Nobuo
Published: June 2003

We have examined the effects of the laser annealing ambient and the number of laser shots on the morphology and the grain size of excimer laser‐annealed poly‐Si films. In the case of a high oxygen partial pressure (> 10e−3Torr), the surface roughness increases with the number of laser shots. However, the surface roughness decreases as the number of laser shots increases at a low oxygen partial pressure (< 10e−3Torr). The grain size of poly‐Si decreases as the oxygen partial pressure decreases. A thin surface oxide film formed by laser irradiation is the cause of these phenomena. There is no saturation point regarding the surface roughness, even at an oxygen partial pressure of 10e−5Torr, so that it is important to control the oxygen in the laser annealing ambient and on silicon film surfaces in order to control poly‐Si TFT performance. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 42–50, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10098
Simultaneous measurement of permittivity and permeability of lossy sheet using flanged rectangular waveguide
Authors: Hayashi Yukinari , Mishima Gen , Hirayama Koichi , Hayashi Yoshio
Published: June 2003

We describe a method for simultaneously measuring the complex permittivity and the complex permeability of a lossy sheet that is inserted between two flanged rectangular waveguides. The equivalence principle of the electromagnetic fields is applied to the boundary surfaces between the sheet and the waveguides to derive the integral equations while taking the high‐order modes excited at the boundary surfaces into account. Then the method of moments is used in these equations to formulate the direct problem. Newton's method is applied to the inverse problem, and the convergence performance of the solution is examined. Furthermore, the reflection coefficients and the transmission coefficients are measured for some samples, and their complex permittivities and complex permeabilities are estimated from these coefficients. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 32–41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10104
A line structure component using a conducting polymer
Authors: Masuda Koichiro , Satoh Masaharu , Tohya Hirokazu
Published: June 2003

Electromagnetic interference (EMI) of electronic equipment is becoming an increasingly important problem as circuits are operated at faster speeds and higher frequencies. Power supply decoupling is used as a way to trap the RF power generated by switching of LSI and circuits in the neighborhood of the source and suppress its propagation to the environment. However, the capacitors used in conventional decoupling devices cannot cover the entire bandwidth necessary with one device. Therefore, several types of capacitors are combined. Nevertheless, it is difficult to suppress frequencies exceeding several hundred megahertz. This paper discusses the fabrication and evaluation of a power supply decoupling device that can cover a wide frequency range with one device. The tested device emulates a shielded microstrip transmission line and has a configuration consisting of aluminum as the inner conductor, aluminum oxide (Al2O3) as the dielectric substrate, and a conductive polymer as the outer conductor. Evaluation of the power transmission characteristics (S21) shows that the tested device is effective over a wide frequency range. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 23–31, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10128
Application of multigrid method to lightwave propagation in two‐dimensional optical waveguide
Authors: Yokota Mitsuhiro , Sugio Naomi
Published: June 2003

The multigrid method widely used in computational fluid dynamics is applied to the problem of propagation of an optical wave in an optical waveguide. This method is a technique for accelerating the convergence speed of the relaxation method. The electromagnetic field components contain various frequency components. Higher‐frequency components contain local effects of the shape. On the other hand, the lower‐frequency components contain more global aspects. By using this phenomenon, the discretized equations are made to reduce errors corresponding to the grid size. As a numerical example, linear and nonlinear directional couplers are treated and the effects of the number of levels and the number of iterations in the multigrid method are studied. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 14–22, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10131
Improved resolution of thick‐film resist (effect of development technique)
Authors: Sensu Yoshihisa , Sekiguchi Atsushi , Miyake Yasuhiro
Published: June 2003

In view of the fact that little analysis of the mechanism for the achievement of high resolution or a high aspect ratio in the thick‐film resist process has been performed, we have studied development properties with respect to differences between the development methods employed for pattern formation using thick‐film resists. This study identifies the most effective development method for thick‐film resists and reports the mechanism of development. For this investigation, we use a development rate measurement system, a mask aligner, and lithography simulator to examine the dipping development method, the step puddle development method, the vibration development method, and the reverse development method. We employ a thick‐film positive resist composed of diazo‐naphthoquinone (DNQ) and Novolak resin, which is coated on a silicon substrate to a thickness of 24 µm. After prebaking, the coated substrate is placed in a vacuum desiccator to remove water, followed by immersion in deionized water for a fixed period. A mask pattern is transferred to the resist‐coated substrate with a Mask Aligner Q4000 made by Quintel Corporation, and then the rate of development is measured. A laser microscope analysis of the result indicates that the step puddle development method gives the highest pattern resolution and sharpness, followed by the vibration development method, the dipping development method, and lastly the reverse development method. The mechanisms of the development are studied by comparing the development contrast and the energy of activation involved in each development method, and by conducting resist pattern simulations. The results indicate that the factors responsible for retarding the progression of the development process and causing a degradation of pattern profile and resolution are development inhibition due to N2 released from inside the resist during the development process, and due to products that are dissolved in the development solution. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 1–13, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10141
Surface defects on SOI wafers and their influence on device characteristics
Authors: Naruoka Hideki , Hattori Nobuyoshi , Iwamatsu Toshiaki , Ipposhi Takashi , Sudo Mitsuro , Nakai Tetsuya , Yamamoto Hidekazu , Mashiko Yoji
Published: June 2003

We have classified the surface defects present in two kinds of wafers processed by high‐dose separation by implanted oxygen (HD‐SIMOX), for which the starting substrates were grown by the Czochralski (CZ) and epitaxial (EPI) methods, respectively. Our classification included several kinds of categories, based on our investigations of the densities and distributions of these defects. In addition, we varied the shapes of the defects by sacrificing the oxide layers, and investigated their cross‐sectional structure. The two main classes of surface defects are pit‐type defects and undulation‐type defects. Our view is that the former are attributable to grown‐in defects such as crystal‐originated particles (COPs), the latter to the behavior of these particles during the implantation and SIMOX anneal stages. We also investigated the influence of surface defects on the integrity of the oxide layer and the quality of the buried‐oxide (BOX) material. We found that some undulation‐type defects that lose the silicon‐on‐insulator (SOI) layer during the thinning process can degrade the oxide film integrity, while those defects that lose both the BOX layer and the SOI layer during the thinning process can lead to both degradation of the oxide film integrity and BOX leakage. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 64–72, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1125
Organic EL device using SrOx as an electron injection material
Authors: Tanaka Kuniaki , Maeda Kenji , Usui Hiroaki
Published: June 2003

Strontium oxide (SrOx) is known as an alkaline‐earth metal oxide that has a low work function. We have prepared an organic EL device with an ITO/PVCz (polyvinylcarbazole)/Alq/SrOx/Al structure. SrOx was stacked as an electron injection layer on the Alq (aluminum quinolinol complex) emission layer by means of a reactive vapor deposition method by evaporating metallic strontium under an oxygen atmosphere. By inserting the SrOx film of less than 5 nm in thickness, significant improvements were achieved in the device properties, including luminance, lifetime, threshold voltage, and efficiency. XPS measurement and AFM analysis showed that the film morphology of the SrOx layer had an island structure. The oxidation of SrOx was enhanced by setting the oxygen partial pressure for the reactive vapor deposition to 10−3 to 10−2 Pa, which yielded the optimum EL properties. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(7): 73–80, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1126
Synthesis of N,N‐Disubstituted 1‐Cyanocyclopropanecarboxamides
Authors: Yamagata Kenji , Okabe Fumi , Tagawa Yoshinobu
Published: June 2003

2‐(Disubstituted amino)‐4,5‐dihydro‐3‐furancarbonitriles 1a−i reacted with acetyl chloride to yield the corresponding ring‐opening products 2a−i. The cyclization of compounds 2a−f with bases gave the corresponding N,N‐disubstituted 1‐cyanocyclopropanecarboxamides 3a−c and (E)‐1‐cyano‐2‐phenylcyclopropanecarboxamides 3d−f. The same compounds 3d−f were also obtained by treatment of compounds 2g−i with sodium methoxide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Photochromism of Novel Chromene Derivatives Bearing a Monoazacrown Ether Moiety
Authors: Ahmed Saleh A. , Tanaka Mutsuo , Ando Hisanori , Iwamoto Hitoshi , Kimura Keiichi
Published: June 2003

Crowned chromenes − four novel naphthopyrans (chromenes) bearing monoaza‐12‐crown‐4, ‐15‐crown‐5, ‐18‐crown‐6, and a noncyclic analogue at the 5‐position − were synthesized, and their photochromism in acetonitrile was examined in the presence of alkali and alkaline‐earth metal ions. Incorporation of crown ether units to chromene moieties facilitated to a great extent both the thermal isomerization and photoisomerization of the chromene moiety, reflecting the metal‐ion‐binding ability of the crown ether moiety. Comparison of the crowned chromenes with the corresponding crowned spirobenzopyrans reveals that photochromism of the crowned chromene reflects an interaction between the metal ion and the crown ether moiety that is stronger than that of the crowned spirobenzopyran, and shows only positive photochromism with significant red‐shifts in the UV/Vis absorption spectra, in contrast to the crowned spirobenzopyrans reported previously. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Preparation of 1‐Ethynylpyrene‐Modified DNA via Sonogashira‐Type Solid‐Phase Couplings and Characterization of the Fluorescence Properties for Electron‐Transfer Studies
Authors: Rist Manuela , Amann Nicole , Wagenknecht Hans‐Achim
Published: June 2003

A range of 1‐ethynylpyrene‐modified oligonucleotides (Py−≡−dU) has been prepared by a special semi‐automated strategy using Sonogashira‐type cross‐coupling conditions in the solid phase. The absorption and fluorescence properties of the Py−≡−dU‐modified single strands and their corresponding double‐stranded duplexes have been characterized. The presented spectra show that the Py−≡−dU emission is quenched in DNA duplexes bearing a thymine or cytosine adjacent to the Py−≡−dU group. This shows that the Py−≡−dU moiety is able to inject an electron into the base stack while simultaneously acting as a spectroscopic label to enable the observation of these processes. Hence, Py−≡−dU‐modified oligonucleotides are promising donor systems in order to study electron injection and electron transport in DNA spectroscopically. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: The Effect of High Pressure on the Heck Reaction − A Contribution to a Deeper Understanding of the Mechanism (Eur. J. Org. Chem. 13/2003)
Authors: Buback Michael , Perković Thomas , Redlich Stefan , Meijere Armin de
Published: June 2003

The cover picture shows the influence of high pressure on the Heck cross‐coupling reaction. As reflected by its generally accepted mechanism, this palladium‐catalyzed reaction proceeds in a number of distinctly different steps, some of which ought to be retarded by high pressure. Yet, the overall effect leads to a significant acceleration, and the reaction has a negative volume of activation. The kinetic parameters were determined by monitoring the reaction in a massive metal cylinder − as seen in the background − by on‐line FT‐IR spectroscopy. Details are discussed in the article by A. de Meijere et al. on p. 2375 ff.
The flame retardant mechanism of polyolefins modified with chalk and silicone elastomer
Authors: Hermansson Anna , Hjertberg Thomas , Sultan Bernt‐Åke
Published: June 2003

This paper presents the current understanding of the flame retardant mechanism of Casico™. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from 13C MAS‐NMR and 29Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd.
Maintaining the stability of a leapfrog scheme in the presence of source terms
Authors: Kim Cheolwan
Published: June 2003

The instability encountered by applying the upwind leapfrog method to the advection equation having a source term is resolved. The source term is eliminated by transforming the governing equation. Two types of transformation are examined and the method of the space transformation leads to a stable and accurate scheme for the one‐dimensional advection equation. The method is also extended to the two‐dimensional acoustic equations in polar co‐ordinates. Copyright © 2003 John Wiley & Sons, Ltd.
A new VOF‐based numerical scheme for the simulation of fluid flow with free surface. Part I: New free surface‐tracking algorithm and its verification
Authors: Kim Min Soo , Lee Woo Il
Published: June 2003

Numerical simulation of fluid flow with moving free surface has been performed. For the free surface flow, a volume of fluid (VOF)‐based algorithm utilizing a fixed grid system has been investigated. In order to reduce numerical smearing at the free surface represented on a fixed grid system, a new free surface‐tracking algorithm based on the donor–acceptor scheme has been proposed. Novel features of the proposed algorithm are characterized by two numerical tools; the orientation vector to represent the free surface orientation in each cell and the baby‐cell to determine the fluid volume flux at each cell boundary. The proposed algorithm can be easily implemented in any irregular non‐uniform grid systems usually encountered in the finite element method (FEM). Moreover, the proposed algorithm can be extended and applied to the 3D free surface flow problems without additional efforts. For computation of unsteady incompressible flow, a finite element approximation based on the explicit fractional step method has been adopted. In addition, the streamline upwind/Petrov–Galerkin (SUPG) method has been implemented to deal with convection dominated flows. Combination of the proposed free surface‐tracking scheme and the explicit fractional step formulation resulted in an efficient solution algorithm. Validity of the present solution algorithm was demonstrated from its application to the broken dam and the solitary wave propagation problems. Copyright © 2003 John Wiley & Sons, Ltd.
Adaptive strategy of transonic flows over vibrating blades with interblade phase angles
Authors: Yang S. Y.
Published: June 2003

An error indicator and a locally implicit scheme with anisotropic dissipation model on dynamic quadri‐ lateral–triangular mesh are developed to study transonic flows over vibrating blades with interblade phase angles. In the Cartesian co‐ordinate system, the unsteady Euler equations with moving domain effects are solved. The error indicator, in which unified magnitudes of dynamic grid speed, substantial derivative of pressure, and substantial derivative of vorticity magnitude are incorporated to capture the unsteady wave behaviours and vortex‐shedding phenomena due to unsteadiness. To assess the accuracy of the locally implicit scheme with anisotropic dissipation model on quadrilateral–triangular mesh, two flow calculations are performed. Based on the comparison with the related numerical and experimental data, the accuracy of the present approach is confirmed. According to the high‐resolutional result on the adaptive mesh, the unsteady pressure wave, shock and vortex‐shedding behaviours are clearly demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of under‐relaxation factors on turbulent flow simulations
Authors: Barron R. M. , Salehi Neyshabouri Ali A.
Published: June 2003

Under‐relaxation factors are significant parameters affecting the convergence of a numerical scheme. Some earlier work has been done to optimize these parameters, but this was restricted to special flow domains, and the range of changes for under‐relaxation factors and convective algorithms are limited.

In this paper, the effects of changing under‐relaxation factors for different variables, different convective schemes and grid sizes on the convergence of the numerical solution of three 2D turbulent flow situations are studied. These three flows are duct flow, trench flow and inclined free falling jet flow. Copyright © 2003 John Wiley & Sons, Ltd.
Hygromycin B‐selected cell lines from GAL4‐regulated pUAST constructs
Authors: Makridou Panagiota , Burnett Camilla , Landy Tim , Howard Ken
Published: June 2003

Summary: Here we report the generation of stable, selectable Drosophila S2 cell lines using the UAS‐GAL4 system. Cloning of the hygromycin resistance gene into the pUAST vector and cotransfection with other pUAST constructs in S2 cells results in coexpression of up to four different proteins under hygromycin selection. Protein expression is driven by the ubiquitous Actin5C‐GAL4 driver and cell cultures are maintained in hygromycin‐supplemented, serum‐free media to ensure constitutive protein production. Visual comparison of cells cotransfected with GFP and RFP demonstrates a uniform cell population expressing both markers simultaneously, while Western blot analysis shows concurrent expression of MYC3‐tagged proteins. In addition, fluorescent cell sorting (FACS) analysis shows that 80% of the total cell population express the GFP marker. Our data indicate that using this technique it is possible to establish stable, selectable cell lines that provide a pool of readily accessible protein. This facilitates protein‐based studies and abolishes the need to carry out time‐consuming and expensive transfections. genesis 36:83–87, 2003. © 2003 Wiley‐Liss, Inc.
Cre‐mediated recombination in the skin melanocyte lineage
Authors: Delmas Véronique , Martinozzi Silvia , Bourgeois Yveline , Holzenberger Martin , Larue Lionel
Published: June 2003

Summary: Organ‐specific expression of a Cre recombinase allows the analysis of gene function in a particular tissue or cell type. Using a 6.1 kb promoter from the mouse tyrosinase gene, we generated and characterized two lines of transgenic mice that express Cre recombinase in melanoblasts. Utilizing a Cre‐responsive reporter mouse strain, genetic recombination was detected in the melanoblasts of the skin from embryonic day 11.5. In addition, Cre‐expression was detected in the skin and eyes of mice. Cre transgene activity was occasionally detected in the brain and peripheral nerves but not in other tissues. When Tyr::Cre mice were crossed with mice carrying a homozygous loxP conditional mutation for the insulin‐like growth factor receptor gene (Igf1r), Cre‐melanoblast‐specific recombination pattern was confirmed and no abnormal phenotype was observed. In conclusion, Tyr::Cre transgenic mice provide a valuable tool to follow the cell lineage and to examine gene function in melanocyte development and transformation. genesis 36:73–80, 2003. © 2003 Wiley‐Liss, Inc.
Skeletal myogenesis in the mouse esophagus does not occur through transdifferentiation
Authors: Rishniw Mark , Xin Hong‐Bo , Deng Ke‐Yu , Kotlikoff Michael I.
Published: June 2003

Summary: To determine the developmental history of murine esophageal skeletal muscle, smooth muscle cells were fate mapped by lineage‐specific recombination and phenotypically marked by eGFP. Examination of embryonic and postnatal tissues revealed that esophageal skeletal muscle does not arise from transdifferentiation of committed smooth muscle cells. genesis 36:81–82, 2003. © 2003 Wiley‐Liss, Inc.
DSP1 interacts with bicoid for knirps enhancement
Authors: Daulny A. , Rappailles A. , Landemarre L. , Locker D. , Decoville M.
Published: June 2003

Summary: DSP1 is an HMG‐box protein which has been implicated in the regulation of homeotic genes in Drosophila melanogaster. Here we report that DSP1 is also involved in the regulation of the kni gap gene. Analysis of the phenotype of a null mutation of dsp1 (dsp11) reveals that the absence of maternal DSP1 results in A4 segmentation defects that are correlated with a diminution of the kni expression domain. Genetic interaction studies demonstrate that a bcd mutation enhances the A4 defect of dsp11. We present in vitro and in vivo evidences for a direct interaction between DSP1 and Bicoid, mediated by the BCD homeodomain and the HMG box of DSP1. Finally, we show by immunoprecipitation of cross‐linked chromatin the association of DSP1 with the kni‐regulating region and discuss the potential mechanism of DSP1‐mediated activation of kni. genesis 36:104–113, 2003. © 2003 Wiley‐Liss, Inc.
Effect of histone deacetylase inhibitors on heat shock protein gene expression during Xenopus development
Authors: Ovakim Daniel H. , Heikkila John J.
Published: June 2003

Summary: We examined the effect of histone deacetylase inhibitors (HDIs), trichostatin A (TSA), valproic acid (VPA), and sodium butyrate (NaB) on heat shock protein (hsp) gene expression during early Xenopus laevis development. HDIs enhance histone acetylation and result in the relief of repressed chromatin domains and ultimately increase the accessibility of transcription factors to target cis‐acting regulatory sites. Treatment of embryos with HDIs enhanced the heat shock‐induced accumulation of hsp70 mRNA in post‐midblastula stage embryos. No effect was observed with actin mRNA or other hsp70 family members including heat shock cognate 70 and immunoglobulin binding protein. Normally, hsp30 genes are not heat‐inducible until the late neurula or early tailbud stage of development. Treatment with HDIs resulted in heat‐induced expression of hsp30 genes at the gastrula stage with enhanced heat‐induced accumulation in neurula and tailbud stages. HDI treatment alone did not induce the accumulation of hsp70 or hsp30 mRNA. Whole‐mount in situ hybridization verified the RNA blot analyses and additionally revealed that TSA treatment did not result in any major alterations in the spatial pattern of stress‐induced hsp70 or hsp30 mRNA accumulation in early embryos. This study suggests that the states of Xenopus hsp70 and 30 chromatin are subject to repression beyond the midblastula transition. genesis 36:88–96, 2003. © 2003 Wiley‐Liss, Inc.
Cerebellar granule cell Cre recombinase expression
Authors: Aller M.I. , Jones A. , Merlo D. , Paterlini M. , Meyer A.H. , Amtmann U. , Brickley S. , Jolin H.E. , McKenzie A.N.J. , Monyer H. , Farrant M. , Wisden W.
Published: June 2003

Summary: The cerebellum maintains balance and orientation, refines motor action, stores motor memories, and contributes to the timing aspects of cognition. We generated two mouse lines for making Cre recombinase‐mediated gene disruptions largely confined to adult cerebellar granule cells. For this purpose we chose the GABAA receptor α6 subunit gene, whose expression marks this cell type. Here we describe mouse lines expressing Cre recombinase generated by 1) Cre knocked into the native α6 subunit gene by homologous recombination in embryonic stem cells; and 2) Cre recombined into an α6 subunit gene carried on a bacterial artificial chromosome (BAC) genomic clone. The fidelity of Cre expression was tested by crossing the mouse lines with the ROSA26 reporter mice. The particular α6BAC clone we identified will be valuable for delivering other gene products to cerebellar granule cells. genesis 36:97–103, 2003. © 2003 Wiley‐Liss, Inc.
Expression of laminin chains by central neurons: Analysis with gene and protein trapping techniques
Authors: Yin Yong , Kikkawa Yamato , Mudd Jacqueline L. , Skarnes William C. , Sanes Joshua R. , Miner Jeffrey H.
Published: June 2003

Summary: Laminins exert numerous effects on neurons in vitro, but expression of laminin subunit genes by neurons in vivo remains controversial. To reexamine this issue, we generated mice from ES cells in which the laminin α1, α5, β1, and γ1 genes had been “trapped” by insertion of a histochemically detectable selectable marker, βgeo (β‐galactosidase fused to neomycin phosphotransferase). The presence of laminin‐βgeo fusion proteins was assayed histochemically and immunochemically, revealing expression of laminin β1 and γ1 genes, but not α chain genes, by defined subsets of neurons in brain and retina. We also used the gene traps in a novel way to assay expression of endogenous laminin subunits, which were barely detectable by ordinary immunohistochemical methods. The trapping vector included a transmembrane domain that anchors proteins otherwise destined for secretion. Laminin α/β/γ heterotrimers are assembled intracellularly, and we show that the trapped laminin γ1 fusion protein “co‐trapped” endogenous β1 intracellularly. The laminin γ1 fusion was also able to co‐trap transgene‐derived α chains, but we detected no co‐trapped endogenous α chains. The co‐trapping method may be generally useful for identifying proteins or isolating protein complexes associated with trapped gene products. genesis 36:114–127, 2003. © 2003 Wiley‐Liss, Inc.
An Early Picture of Cancer
Authors: Bremer Christoph
Published: June 2003

Novel optical techniques are making it possible to visualise enzymes responsible for the spread of cancer cells
Only at the Start is Everyone Equal
Authors: Abele‐Brehm Andrea E.
Published: June 2003

The careers of men and women still take different paths. The career patterns of male and female academics also differ. Scientists are studying and comparing the reasons for this
Of Krauts and Frogs: Stereotypes and their Uses
Authors: Mohrmann Ruth‐E. , Meyer Silke
Published: June 2003

Seen through the eyes of an Englishman travelling in 18th century Europe: historical caricatures and illustrations provide an unexpected insight into contemporary and current clichés and their contexts
Ethical aspects of technical safety
Authors: Gethmann Carl Friedrich
Published: June 2003

Uncertainty and inequality are the most important phenomena that lead to the situation in which the modern technical age, in contrast to the premodern technical phase, gives rise to specifically moral problems which in the premodern era played only a marginal role or no role at all. So modern, technically constituted societies must learn to develop from the initial perception of dangers to a rational risk assessment. To justify this ethical obligation, the first section discusses the relation between danger and risk. The problem of weighing risks is analyzed in the second section; in this context the concept of pragmatic consistency is introduced. In the third section, the term safety is explicated as a comparative concept by means of the principle of pragmatic consistency. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 243–252, 2003.
Changes in expression and activity of glutathione S‐transferase in different organs of schistosoma haematobium‐infected hamster
Authors: Sheweita S. A. , Mostafa M. H. , Ebid F. , El‐Sayed W.
Published: June 2003

Schistosomiasis is a major health problem in many subtropical developing countries, causing a number of serious pathologies, including bladder cancer. Most of the toxic compounds formed as a result of these infestations are derived either exogenously or formed endogenously and can be conjugated with glutathione (GSH) via glutathione S‐transferase (GST). The present study investigates the effect of Schistosma haematobium infection on the activity of GST and glutathione reductase (GR) and levels of glutathione and free radicals (measured as thiobarbituric acid reactive substances) in different organs of the male hamster. The total activity of GST was increased in several organs; in kidney by 50 and 46% at 6 and 10 weeks postinfection, respectively, and in bladder tissues by 169, 23, and 130% at 2, 4, and 6 weeks postinfection, respectively. In support of this, the expression of GST isozymes was also induced in kidney and bladder tissues at early stages (2, 4, and 6 weeks) and reduced at the later stages of infection (8 and 10 weeks). In contrast, the expression of these isozymes was decreased in the spleen and liver at 2, 4, 6, 8, and 10 weeks postinfection. Also, such activity was decreased in lungs by 74 and 78% and in bladders by 65 and 72% at 8 and 10 weeks postinfection, respectively. GSH levels increased in lungs by 95, 40, and 56% at 2, 4, and 6 weeks and in spleen by 26 and 74% at 4 and 6 weeks, respectively, but decreased at later stages of S. haematobium infection in these organs. The depletion of GSH levels also occurred in bladders by 72 and 54% at 8 and 10 weeks postinfection, respectively. The activity of GR was increased in the livers, lungs, and kidneys of the S. haematobium‐infected hamster. TBARS also increased in the lung by 14, 65, 53, 828, and 624% and in the kidney by 64, 29, 87, 190, and 111%, and in the bladder by 216, 23, 1468, 528, and 1025% at 2, 4, 6, 8, and 10 weeks postinfection, respectively. This study indicates that low GST expression and high levels of free radicals could provide new evidence for damage to the bladder and other organs as a result of S. haematobium infection. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:138–145, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10071
Effect of oral administration of arabic gum on cisplatin‐induced nephrotoxicity in rats
Authors: Al‐Majed Abdulhakeem A. , Abd‐Allah Adel R. A. , Al‐Rikabi Ammar C. , Al‐Shabanah Othman A. , Mostafa Adel M.
Published: June 2003

It has been recently postulated from our laboratory that Arabic gum (AG) offers a protective effect in the kidney of rats against nephrotoxicity induced by gentamicin via inhibiting lipid peroxidation. It has also recently shown a powerful antioxidant effect through scavenging superoxide anions. In this study we utilized a rat model of cisplatin (CP)‐induced nephrotoxicity to determine its peak time following (1, 2, 5, and 7 days) of a single CP (7.5 mg/kg, i.p.) injection. Also, a possible protective effect of cotreatment with AG (7.5 g/kg/day p.o.) on CP‐induced nephrotoxicity was investigated. Biochemical as well as histological assessments were carried out. CP‐induced nephrotoxicity was manifested by significant elevations of the functional parameters blood urea, serum creatinine, and kidney/body weight ratio. Maximum toxic effects of CP were observed 5 days after its injection, while it started after day 1 in the biochemical parameters, such as glutathione depletion in the kidney tissue with concomitant increases in lipid peroxides and platinum content. Additionally, severe necrosis and desquamation of tubular epithelial cells in renal cortex as well as interstitial nephritis were observed after 5 days in CP‐treated animals. Five days after AG cotreatment with CP did not protect the kidney from the damaging effects of CP. However, it significantly reduced CP‐induced lipid peroxidation. These findings suggest that lipid peroxidation is not the main cause of CP‐induced nephrotoxicity but it is rather more dependent on other factors such as platinum disposition in renal interstitial tubules. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:146–153, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10072
Voltage‐dependent ebselen and diorganochalcogenides inhibition of 45Ca2+ influx into brain synaptosomes
Authors: Moretto M. B. , Rossato J. I. , Nogueira C. W. , Zeni G. , Rocha J. B. T.
Published: June 2003

By mediating the Ca2+ influx, Ca2+ channels play a central role in neurotransmission. Chemical agents that potentially interfere with Ca2+ homeostasis are potential toxic agents. In the present investigation, changes in Ca2+ influx into synaptosomes by organic forms of selenium and tellurium were examined under nondepolarizing and depolarizing conditions induced by high KCl concentration (135 mM) or by 4‐aminopyridine (4‐AP). Under nondepolarizing conditions, ebselen (400 μM) increased Ca2+ influx; diphenyl ditelluride (40–400 μM) decreased Ca2+ in all concentrations tested; and diphenyl diselenide decreased Ca2+ influx at 40 and 100 μM, but had no effect at 400 μM. In the presence of KCl as depolarizing agent, ebselen and diphenyl ditelluride decreased Ca2+ influx in a linear fashion. In contrast, diphenyl diselenide did not modify Ca2+ influx into isolated nerve terminals. In the presence of 4‐AP (3 mM) as depolarizing agent, ebselen (400 μM) caused a significant increase, whereas diphenyl diselenide and diphenyl ditelluride inhibited Ca2+ influx into synaptosomes. The results can be explained by the fact that the mechanism through which 4‐AP and high K+ induced elevation of intracellular Ca2+ is not exactly coincident. The mechanism by which diphenyl ditelluride and ebselen interact with Ca2+ channel is unknown, but may be related to reactivity with critical sulfhydryl groups in the protein complex. The results of the present study indicate that the effects of organochalcogenides were rather complex depending on the condition and the depolarizing agent used. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:154–160, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10073
Relationship between expression of HSP70 and metallothionein and oxidative stress during mercury chloride induced acute liver injury in rats
Authors: Reus Isabel Sánchez , Bando Inmaculada , Andrés David , Cascales María
Published: June 2003

Mercury is a highly toxic metal which induces oxidative stress. Metallothionein and heat shock protein 70 (HSP70) are stress proteins involved in response to different stimuli. In the present study rats were administered per oral application by gavage, a single daily dose (0.1 mg/kg) of HgCl2 for 3 consecutive days. To find a relation between these two stress proteins and mercury, parameters of liver injury, redox state of the cells, and the expression and protein levels of HSP70 and metallothionein by Northern and Western blot analysis were assayed either in blood or in liver. HgCl2 at the doses of 0.1 mg/kg induced liver injury detected by a slight increase in serum aspartate aminotransferase and alkaline phosphatase activities and by the enhanced levels of bilirubin. Oxidative stress was detected by a significant decrease in protein–SH and an increase in thiobarbituric acid reactive substances in liver following one dose of mercury. mRNA and protein levels of both metallothionein and HSP70 increased progressively from first to third doses of mercury. We conclude that against low doses of mercury that produce a slight liver injury and oxidative stress, the liver rapidly responds by inducing the expression of metallothionein and HSP70. We suggest that metallothionein induction attenuates the decrease in protein–SH induced by the first dose of mercury, since metallothionein increases the pool of thiol groups in the cytosol eliminating oxygen radicals and inhibiting lipid peroxidation. From these results we can suggest that the changes observed in these stress proteins by the effect of mercury appear to be a response rapidly induced at transcriptional and at translational levels. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:161–168, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10074
Catalyzation of cocaine N‐demethylation by cytochromes P4502B, P4503A, and P4502D in fish liver
Authors: Arinç Emel , Bozcaarmutlu Azra
Published: June 2003

Cocaine N‐demethylation by microsomal cytochrome P450s is the principal pathway in cocaine bioactivation and hepatotoxicity. P450 isozymes involved in N‐demethylation of cocaine have not been elucidated yet and they differ from species to species. In humans and mice, P4503A contributes to cocaine N‐demethylase activity, whereas in rats, both P4503A and P4502B participate. In the present study, contribution of different P450 isozymes to cocaine N‐demethylase activity was studied in vitro with fish liver microsomes. The specific cocaine N‐demethylase activity was found to be 0.672 ± 0.22 nmol formaldehyde formed/min/mg protein (mean ± SD, n = 6). Cocaine N‐demethylase exhibited biphasic kinetics, and from the Lineweaver–Burk plot, two Km values were calculated as 0.085 and 0.205 mM for the high‐ and low‐affinity enzyme. These results indicate that N‐demethylation of cocaine in mullet liver microsomes is catalyzed by at least two cytochrome P450 isozymes. Inhibitory effects of cytochrome P450 isozyme‐selective chemical inhibitors, ketoconazole, cimetidine, SKF‐525A, and quinidine, on cocaine N‐demethylase activity were studied at 50, 100, and 500 μM concentrations of these inhibitors. At 100 μM final concentrations, ketoconazole (P4503A inhibitor), SKF‐525A (inhibitor of both P4502B and P4503A), and cimetidine (P4503A inhibitor) inhibited N‐demethylation activity by 73, 69, and 63%, respectively. Quinidine, P4502D‐specific inhibitor, at 100 μM final concentration, reduced N‐demethylation activity down to 64%. Aniline, a model substrate for P4502E1, did not alter N‐demethylase activity in the final concentration of 100 μM. IC50 values were calculated to be 20 μM for ketoconazole, 48 μM for cimetidine (both specific P4503A inhibitors), 164 μM for quinidine (P4502D inhibitor), and 59 μM for SKF‐525A (inhibitor of both P4503A and P4502B). The contribution of P4502B to cocaine N‐demethylase activity in mullet liver microsomes was further explored by the use of purified mullet cytochrome P4502B in the reconstituted system containing purified mullet P450 reductase and lipid. The turnover number was calculated as 4.2 nmol HCOH/(min nmol P450). Overall, these results show that P4503A and P4502B are the major P450s responsible for N‐demethylation of cocaine, whereas contribution of P4502D is a minor one, and P4502E1 is not involved in the N‐demethylation of cocaine in mullet liver microsomes. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:169–176, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10075
Prophylactic protection by N‐acetylcysteine against the pulmonary injury induced by 2‐chloroethyl ethyl sulfide, a mustard analogue
Authors: Das Salil K. , Mukherjee Shyamali , Smith Milton G. , Chatterjee Diptendu
Published: June 2003

Mustard gas exposure causes adult respiratory distress syndrome associated with lung injury. The purpose of this study was to investigate whether an antioxidant, such as N‐acetylcysteine (NAC), has any protective effect. Guinea pigs were given single exposure (0.5–6 mg/kg body weight) of 2‐chloroethyl ethyl sulfide (CEES) as a mustard analogue intratracheally and maintained for various lengths of time (1 h to 21 days). Within 1 h of CEES infusion at 4 mg/kg, high levels of tumor necrosis factor α (TNF‐α), ceramides, and nuclear factor κB accumulated in lung and alveolar macrophages. Both acid and neutral sphingomyelinases were activated within 4 h. These signal transduction events were associated with alteration in the oxygen defense system. Within 1 h of exposure to CEES (6 mg/kg body weight), there was 10‐fold increase in the 125I‐BSA leakage into lung tissue, indicating severe lung injury. Although low level of CEES exposure (0.5 mg/kg body weight) produced symptoms of chemical burn in lung as early as 1 h after exposure, the severity of edema, congestion, hemorrhage, and inflammation increased progressively with time (1 h to 21 days). Feeding of single dose of NAC (0.5 g) by gavage just before the CEES infusion was ineffective to counteract these effects. However, consumption of the antioxidant in drinking water for 3 or 30 days prior to CEES exposure significantly inhibited the induction of TNF‐α, activation of neutral and acid sphingomyelinases, production of ceramides, activation of caspases, leakage of 125I‐bovine serum albumin (125I‐BSA) into lung tissue, and histological alterations in lung. Pretreatment with NAC for 3 and 30 days protected against 69–76% of the acute lung injury. Therefore, NAC may be an antidote for CEES‐induced lung injury. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:177–184, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10076