bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cloning and expression analysis of the chick DAN gene, an antagonist of the BMP family of growth factors
Authors: Gerlach‐Bank Lisa M. , Ellis Amanda D. , Noonen Bridgette , Barald Kate F. 
Published: August 2002

AbstractDifferential screening‐selected gene aberrative in neuroblastoma (DAN) is a member of a cystine knot protein family that includes Cerberus and Gremlin. First isolated in a screen to identify genes down‐regulated in transformed rat fibroblasts, DAN has subsequently been cloned in Xenopus, mouse, and human. Overexpression of DAN suppresses the transformed phenotype and retards the cell's entry into S phase. Biochemical analyses have demonstrated DAN's ability to bind bone morphogenetic proteins and antagonize their signaling activity. In this study, chick DAN was cloned and sequenced, revealing a conserved cystine knot region as well as an N‐glycosylation site. A riboprobe was designed from the 3′ chick DAN coding sequence and used for analysis of DAN in the developing chick embryo by in situ hybridization. Chick DAN was expressed beginning at stage 10 in the developing somites and the medial otic epithelium. Expression in the neural layer of the eye became apparent at stage 14. By stage 17, expression had expanded to the base of the hindbrain. Limb bud labeling began at stage 20, whereas expression in the branchial arches appeared at stage 25. Chick DAN expression generally corresponded to that of mouse DAN expression as shown by comparative in situ hybridization. However, chick DAN was found in the otic epithelium and notochord, whereas mouse DAN was restricted to the overlying otic ectomesenchyme and was absent from the notochord. This observation suggests that DAN may play different roles in chick and mouse otic and notochord development. © 2002 Wiley‐Liss, Inc.
Spatial and temporal distribution of nerves, ganglia, and smooth muscle during the early pseudoglandular stage of fetal mouse lung development
Authors: Tollet Jenny , Everett Alan W. , Sparrow Malcolm P. 
Published: August 2002

AbstractNeural tissue and smooth muscle appear early in the developing fetal lung, but little is known of their origin and subsequent distribution. To investigate the spatial and temporal distribution of nerves, ganglia, and airway smooth muscle during the early pseudoglandular stage, fetal mouse lungs at embryonic days (E) 11 to 14 were immunostained as whole‐mounts and imaged by confocal microscopy. At E11, the primordial lung consisted of the future trachea and two budding epithelial tubules that were covered in smooth muscle to the base of the growing buds. The vagus and processes entering the lung were positive for the neural markers PGP 9.5 (protein gene product 9.5) and synapsin but no neurons were stained at this stage. An antibody to p75NTR revealed neural crest cells on the future trachea as well as in the vagus and in processes extending from the vagus to the lung. This finding indicates that even though neuronal precursors are already present at this stage, they are still migrating into the lung. By E12, neural tissue was abundant in the proximal part of the lung and nerves followed the smooth muscle‐covered tubules to the base of the growing buds. At E13 and E14, a neural network of interconnected ganglia, innervated by the vagus, covered the trachea. The postganglionic nerves mainly followed the smooth muscle‐covered tubules, but some extended out into the mesenchyme beyond the epithelial buds. Furthermore, we show in a model of cultured lung explants that neural tissue and smooth muscle persist and continue to grow and differentiate in vitro. By using fluorescent markers and confocal microscopy, we present the developing lung as a dynamic structure with smooth muscle and neural tissue in a prime position to influence growth and development. © 2001 Wiley‐Liss, Inc.
Becoming glial in the neural retina
Authors: Vetter Monica L. , Moore Kathryn B. 
Published: August 2002

AbstractDuring development of the vertebrate neural retina, multipotent stem cells give rise to retinal neurons as well as to Müller cells, the principal glial population in the retina. Recent studies have shed light upon the extracellular and intracellular signaling pathways that regulate Müller glial cell genesis. Emerging evidence demonstrates that activation of the Notch signaling pathway can play a role in regulating Müller cell development as well as gliogenesis in other parts of the central nervous system. Cyclin dependent kinase (CDK) inhibitors of the Cip/Kip subfamily are cell cycle regulators that can regulate progenitor proliferation during retinal development, but also regulate the proliferation of Müller glia when they become activated in response to stress or injury. Surprisingly this class of proteins can also promote the development of Müller glia. In this review we discuss the role of both Notch and the CDK inhibitors in regulating Müller cell development. © 2001 Wiley‐Liss, Inc.
Neonatal estrogen exposure inhibits steroidogenesis in the developing rat ovary
Authors: Ikeda Yayoi , Nagai Akiko , Ikeda Masa‐Aki , Hayashi Shinji 
Published: August 2002

AbstractTreatment of newborn female rats with estrogens significantly inhibits the growth and differentiation of the ovary. To understand the molecular mechanism of estrogen action in the induction of abnormal ovary, we examined the expression profiles of steroidogenic factor 1 (SF‐1) and several of its target genes in the developing ovaries after neonatal exposure to synthetic estrogen, estradiol benzoate (EB) by using reverse transcriptase polymerase chain reaction, in situ hybridization, and immunohistochemistry. Morphologic examination indicated inhibitory effects of estrogen on the stratification of follicles and development of theca and interstitial gland during postnatal ovarian differentiation. The expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side‐chain cleavage cytochrome P450 (P450SCC), which are both essential for steroid biosynthesis, markedly decreased in theca and interstitial cells throughout the postnatal development of the EB‐treated ovary. However, expression of the transcriptional activator of the two genes, SF‐1 was unaffected in theca and interstitial cells, although the number of these cells was lower in the EB‐treated ovary than in the control ovary. The expression of the estrogen mediator, estrogen receptor‐α (ER‐α), diminished specifically in theca cells at P6 and recovered by P14 in the EB‐treated ovary. These results indicate that the effect of estrogens is mediated by means of ER‐α resulting in the down‐regulation of StAR and P450SCC genes during early postnatal development of the ovary. These results suggest that the abnormal ovarian development by neonatal estrogen treatment is closely correlated with the reduced steroidogenic activity, and the data obtained by using this animal model may account in part the mechanism for aberrant development and function of the ovary in prenatally estrogen‐exposed humans. © 2001 Wiley‐Liss, Inc.
TGFβ2 activation status during cardiac morphogenesis
Authors: McCormick Kathleen M. 
Published: August 2002

AbstractTransforming growth factor beta (TGFβ) is secreted as a biologically inactive complex by many cell types in vitro, but little is known of TGFβ's activation status in vivo. This study examined the in vivo expression of active and total (active + acid‐activatable) TGFβ2 in embryonic chicken hearts during cardiac morphogenesis (Hamburger‐Hamilton stage 10–24). The concentration of TGFβ2 was measured by an enzyme‐linked immunoassay that recognized active TGFβ2. Whole heart homogenates were either left untreated to measure active TGFβ2 or treated with acid before assay to measure total (active + acid‐activatable) TGFβ2. Total TGFβ2 concentration increased more than 16‐fold between stage 10/11 and stage 24. Active TGFβ2 concentration was highest at stage 14/15, but overall remained relatively constant varying at most by 2.8‐fold. When expressed relative to total TGFβ2, the amount of active TGFβ2 progressively declined from 70% in stage 10/11 hearts to 7% in stage 24 hearts. The distribution of active and total TGFβ2 was examined by immunostaining with an antibody against active TGFβ2. Before immunostaining, sections were either treated with acid or left untreated to determine the distribution of total and active TGFβ2, respectively. Active TGFβ2 immunostaining was first detected in the endothelium, myocardium, and cardiac jelly of stage 14 hearts. Acid treatment had no effect on the distribution or intensity of immunostaining at this stage. Faint, active TGFβ2 immunostaining was restricted to the ventricular myocardium in stage 18 hearts. Acid treatment resulted in a marked increase in staining intensity in the ventricle, but no staining was observed in the atrium or outflow tract. In stage 24 hearts, faint active TGFβ2 staining was detected in the ventricle before acid treatment. After acid treatment, patches of intense punctate stain were found in all regions of the embryonic heart. Increases in TGFβ2 concentration and immunostaining intensity after acidification suggest that a significant amount of TGFβ2 is in the latent form. Stage‐dependent differences in activation status suggest that activation may be a developmentally regulated process in the chick heart and support the notion that activation is an important step in regulating TGFβ actions in vivo. © 2001 Wiley‐Liss, Inc.
Quantitative axial profiles of retinoic acid in the embryonic mouse spinal cord: 9‐Cis retinoic acid only detected after all‐trans‐retinoic acid levels are super‐elevated experimentally
Authors: Ulven Stine M. , Gundersen Thomas E. , Sakhi Amrit K. , Glover Joel C. , Blomhoff Rune 
Published: August 2002

AbstractStudies using bioassays in normal mice and gene activation in transgenic reporter mice have demonstrated peaks of retinoic acid receptor (RAR) signaling in the brachial and lumbar regions of the spinal cord. Recently, Solomin et al. (Solomin et al. [1998] Nature 395:398–402) detected a retinoid X receptor (RXR) signal in the same region of the developing spinal cord at a slightly later stage than the RAR signal. This finding raises the question of which retinoid ligands underlie RAR and RXR signaling in this part of the embryo. Quantitative measurements of regional differences in retinoid profiles have not been reported previously due to limitation in the sensitivity and specificity of available retinoid detection methods. Here, by using a recently developed ultrasensitive HPLC technique (Sakhi et al. [1998] J. Chromatogr. A 828:451–460), we address this question in an attempt to identify definitively the endogenous retinoids present in different regions of the spinal cord at the stages when regional differences in RAR and RXR signaling have been reported. We find a bimodal distribution of all‐trans retinoic acid (at‐RA), the ligand for RARs, and relate this to the expression of several retinoid‐synthesizing enzymes. However, we do not detect 9‐cis‐retinoic acid (9‐cis‐RA), the putative RXR ligand, in any region of the spinal cord unless retinoid levels are massively increased experimentally by gavage feeding pregnant mice with teratogenic doses of at‐RA. This study provides for the first time quantitative profiles of endogenous retinoids along the axis of the developing spinal cord, thereby establishing a foundation for more definitive studies of retinoid function in the future. It sets definite limits on how much 9‐cis‐RA potentially is present and demonstrates that at‐RA predominates over 9‐cis‐RA by at least 30‐ to 180‐fold in different spinal cord regions. © 2001 Wiley‐Liss, Inc.
Egocentric mental rotation in Hungarian dyslexic children
Authors: Karádi Kázmér , Kovács Beatrix , Szepesi Tímea , Szabó Imre , Kállai János 
Published: August 2002

AbstractA mental rotation task was given to 27 dyslexic children (mean age 9 years, 2 months) and to 28 non‐dyslexic children (mean age 8 years, 8 months). Pictures of right and left hands were shown at angles of 0, 50, 90 and 180 degrees, and the subjects were required to indicate whether what was shown was a right hand or a left hand. It was found that, in this task, the dyslexics did not show the normal pattern of response times at different angles, and also, that they made more errors than the controls. It is argued that this result is compatible with hypothesis that, in typical cases of dyslexia, there is a malfunctioning in the posterior parietal area. Copyright © 2001 John Wiley & Sons, Ltd.
Serum beta‐carotene in anorexia nervosa patients: A case‐control study
Authors: Boland Benoît , Beguin Claire , Zech Francis , Desager Jean‐Pierre , Lambert Michel 
Published: August 2002

AbstractObjectiveTo study the prevalence of hypercarotenemia in a large cohort of patients with anorexia nervosa (AN), to compare serum beta‐carotene (βC) values among restricting and purging AN subjects, and to investigate whether hypercarotenemia is related to an increase in low‐density lipoprotein (LDL) cholesterol.MethodRetrospective case‐control study including 101 female patients and 95 age‐matched normal controls in whom fasting serum βC and lipid profiles were determined.ResultsThe prevalence of hypercarotenemia (>200 μg/dl) in the AN population was 62%. Mean serum βC level was significantly higher in AN patients than in controls (237 ± 103 vs. 160 ± 45 μg/dl, p < .0001). Among AN patients, the level was higher in restricters than in purgers (271 ± 110 vs. 186 ± 78 μg/dl, p < .005). Fasting serum total and LDL cholesterol levels were also significantly higher in patients with AN than in controls, but no correlation was found between serum βC and LDL cholesterol values.DiscussionHypercarotenemia is a common finding in AN patients, especially in the restricter subgroup. The high prevalence of elevated serum βC in AN patients supports its diagnostic value in atypical forms of eating disorders. © 2001 by John Wiley & Sons, Inc. Int J Eat Disord 30: 299–305, 2001.
System for measurement of the development parameters of electron beam resists
Authors: Sekiguchi Atsushi , Tajima Keiichi , Matsuzawa Toshiharu , Kurihara Masaaki 
Published: August 2002

AbstractThe accuracy of profile simulation calculations depends heavily on the accuracy of the parameters used. In particular, the development parameters, which represent the development characteristics (profile and sensitivity) of the resist, have a significant effect on profile simulation accuracy. However, as yet there have been almost no studies into methods used to calculate the development parameters for electron beam lithography, nor have there been comparisons of simulation results using these development parameters with observed resist profiles. In light of this, the authors have developed a system for the measurement of development parameters for use in simulations of electron beam lithography, and have undertaken study into the methods used to calculate such development parameters. In addition, the authors have also attempted to compare simulation results with observed resist profiles. Specifically, a diazanaphthoquinone–novolac resin positive‐type electron beam resist and a chemically amplified positive‐type electron beam resist were used, to which the Fujino development rate equation and the Mack development rate equation were applied. Trial calculations of the development parameters were performed, and the parameters thus obtained were input into a ProBEAM/3D electron beam lithography simulator. The electron beam resist profiles were simulated and compared with SEM images of actual resist samples. From the results it was found that both the Fujino and Mack development rate equations accurately reproduce resist behavior for the novolac positive‐type electron beam resist, whereas the Mack development rate equation was more accurate than the Fujino equation for the chemically amplified positive‐type electron beam resist. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(4): 16–25, 2001
Development of real‐time diagnostic system for VLBI using public communication lines
Authors: Nishio Masanori , Liu Qinghui , Miyazaki Tomoyuki , Kawaguchi Noriyuki , Sasao Tetuo , Omodaka Toshihiro , Morimoto Masaki 
Published: August 2002

AbstractIn this paper, a real‐time diagnostic system for VLBI (Very Long Baseline Interferometer) facilities via public communication lines is proposed, and experimental results to check its diagnostic performance are described with a prototype model. In the system, narrow‐band radio waves such as beacons of geostationary satellites or emission from strong cosmic maser sources are used as test input signals, which make it possible to reduce the signal sampling rate and to transmit sampled data via public communication lines. Thus, diagnostic results can be obtained in real time. The prototype model was connected to the 6‐m radio telescope at the Kagoshima VLBI station and the 10‐m radio telescope at the Mizusawa VLBI station, and a test operation was conducted using beacon waves of satellites. It was found that the correlation results of the data transmitted in real time coincide with those obtained by the conventional procedure for VLBI, confirming the effectiveness of the system. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 1–9, 2001
Quality of a‐Si:H/Si3N4 multilayer films fabricated by double tubed coaxial line type MPCVD system and application of the films to optical circuit element
Authors: Kato Isamu , Sagisaka Masahiko , Sugai Takayoshi , Kamigaichi Takeshi 
Published: August 2002

AbstractThe object of this research was the fabrication of high‐quality a‐Si:H/Si3N4 multilayer films with ultrathin multilayered configurations to serve as a new photonic material, as well as the evaluation of the film quality and applications to photonics. The authors have succeeded in controlling the thickness of the multilayer film at subnanometer order as indicated by the X‐ray diffraction peak of the a‐Si:H/Si3N4 multilayer film. The theoretical curve and the experimental results for the optical energy band gap agree well for multilayer films fabricated by varying the thickness of the a‐Si:H layer while the thickness of the Si3N4 layer is kept constant, and hence excellent multilayer films are obtained. These multilayer films are applied to optical waveguides. The optical waveguide with an ultrathin multilayer structure, much thinner than the wavelength λ of the guided light, is expected to exhibit an anomalous propagation characteristic. It is found that the TM mode is transmitted while the TE mode is cut off in the present multilayer slab waveguide. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 1–7, 2001
Application layer access path selection by using mobile proxy agents
Authors: Tomikawa Yuki , Takai Yoshiaki 
Published: August 2002

AbstractThis paper deals with access path selection algorithms at an application layer. We focus on the independent property of proxies. If there is a possibility of choosing a proxy between a server and a client, better communication delay would be achieved by using an appropriate proxy. We propose a mobile proxy agent, which measures the communication delay, moves into an adequate host, and then becomes a proxy used exclusively for a client. The mobile proxy agent acts as a disposable personal proxy. Simulations of a wide‐area network show that the mobile proxy agents are well adaptable to the environmental changes of the network. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(12): 46–53, 2001
Energy tax harmonization in the European Union: a proposal based on the internalization of environmental external costs
Authors: Dorigoni Susanna , Gullí Francesco 
Published: August 2002

AbstractEnergy tax harmonization represents a fundamental target within the European Union. In fact fiscal harmonization is a crucial step towards the creation of a single market. In this article the possibility of achieving such an objective is discussed. The paper consists of two sections. In the first the European taxation on energy products is analysed. This analysis is useful in showing the differences that exist between the European countries that account for the difficulties met so far in the process of harmonization. In this respect we comment on the recent proposal of the Directive of the European Union, which lays down the obligation of minimum levels of taxation in all European member states.In the second section, after simulating the effects related to the adoption of a common environmental taxation (a first best solution based on the internalization of environmental external costs), we propose, as a second best solution, an excise tax harmonization model taking into consideration the specificity of each country and being, as far as possible, coherent with the environmental objective. This model proposes: the introduction of a minimum level of taxation on all products equal to the external cost due to the greenhouse effect (a common carbon tax); the possibility, given to the member states, of deviating from such minimum levels, in accordance with their specific requirements, internalizing in the price of the different products, by means of taxes additional to that CO2 minimum, the external costs associated with other pollutant agents (the same in all countries); the opportunity, in case it should be necessary to exceed the entire external cost, for the member states to apply increases that are in accordance with the environmental objective. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment
Russian environmentalism
Authors: Oldfield Jonathan D. 
Published: August 2002

AbstractThis paper provides an overview of developments relating to Russia's environmental policy and environmental legislation since the break‐up of the Soviet Union. It also highlights general trends evident within the country's environmental movement. All three areas have been characterized by significant change during the last decade.The paper suggests that the effectiveness of environmental policy and legislative change has been undermined by a combination of administrative, financial and operational constraints. These ensure that key policies struggle to extend beyond official rhetoric, a situation similar to that found during the Soviet period. Developments in Russia's environmental policy, particularly since the mid–late 1990s, appear to indicate the emergence of a more utilitarian approach towards the use of natural resources culminating in the removal of the State Committee for the Protection of the Environment during 2000. Russia's environmental movement has been assertive in attempting to keep the environment on the policy agenda in recent years. This is reflected in its efforts to carry out a national referendum during 2000. Nevertheless, its overall influence is limited by a combination of public apathy and political opposition.In view of Russia's potential to influence the European and global environment, the paper concludes by indicating the need for international assistance and co‐operation in order to address the noted policy and legislative weaknesses. Copyright © 2002 John Wiley & Sons, Ltd and ERP Environment.