bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of interleukin-1β-induced Ca2+ signals in mouse cortical astrocytes: roles of store- and receptor-operated Ca2+ entry
Authors: Beskina Olga , Miller Anna , Mazzocco-Spezzia Amparo , Pulina Maria V. , Golovina Vera A.
Published: August 2007

Many neurodegenerative disorders are accompanied by chronic glial activation, which is characterized by the abundant production of proinflammatory cytokines, such as IL-1β. IL-1β disrupts Ca2+ homeostasis and stimulates astrocyte reactivity. The mechanisms by which IL-1β induces Ca2+ dysregulation are not completely defined. Here, we examined how acute and chronic (24–48 h) treatment with IL-1β affect Ca2+ homeostasis in freshly dissociated and primary cultured mouse cortical astrocytes. Cytosolic free Ca2+ concentration ([Ca2+]cyt) was measured with fura-2 using digital imaging. An acute application of 10 ng/ml IL-1β induced Ca2+ mobilization from intracellular stores and activated store-operated Ca2+ entry (SOCE) and receptor-operated Ca2+ entry (ROCE) in both freshly dissociated and cultured actrocytes. Treatment of cultured astrocytes with IL-1β for 24 and 48 h elevated resting [Ca2+]cyt, decreased Ca2+ store content [associated with sarco(endo)plasmic reticulum Ca2+-ATPase 2b downregulation], and augmented ROCE. Based on evidence that receptor-operated, but not store-operated Ca2+ channels are Ba2+ permeable, Ba2+ entry was used to distinguish receptor-operated Ca2+ channels from store-operated Ca2+ channels. ROCE was activated by the diacylglycerol analog, 1-oleoyl-2-acetyl- sn-glycerol (OAG). In the presence of extracellular Ba2+, OAG-induced elevations of cytosolic Ba2+ (fura-2 340-to-380-nm ratio) were significantly larger in astrocytes treated with IL-1β. These changes in IL-1β-treated astrocytes correlate with augmented expression of transient receptor potential cation channel (TRPC)6 protein, which likely mediates ROCE. Knockdown of the TRPC6 gene markedly reduced ROCE. The data suggest that IL-1β-induced dysregulation of Ca2+ homeostasis is the result of enhanced ROCE and TRPC6 expression. The disruption of Ca2+ homeostasis appears to be an upstream component in the cascade of IL-1β-activated pathways leading to neurodegeneration.
Fractal scale-invariant and nonlinear properties of cardiac dynamics remain stable with advanced age: a new mechanistic picture of cardiac control in healthy elderly
Authors: Schmitt Daniel T. , Ivanov Plamen Ch.
Published: August 2007

Heart beat fluctuations exhibit temporal structure with robust long-range correlations, fractal and nonlinear features, which have been found to break down with pathologic conditions, reflecting changes in the mechanism of neuroautonomic control. It has been hypothesized that these features change and even break down also with advanced age, suggesting fundamental alterations in cardiac control with aging. Here we test this hypothesis. We analyze heart beat interval recordings from the following two independent databases: 1) 19 healthy young (average age 25.7 yr) and 16 healthy elderly subjects (average age 73.8 yr) during 2 h under resting conditions from the Fantasia database; and 2) 29 healthy elderly subjects (average age 75.9 yr) during ≈8 h of sleep from the sleep heart health study (SHHS) database, and the same subjects recorded 5 yr later. We quantify: 1) the average heart rate (); 2) the SD σR-Rand σΔR-Rof the heart beat intervals R-R and their increments ΔR-R; 3) the long-range correlations in R-R as measured by the scaling exponent αR-Rusing the Detrended Fluctuation Analysis; 4) fractal linear and nonlinear properties as represented by the scaling exponents αsgnand αmagfor the time series of the sign and magnitude of ΔR-R; and 5) the nonlinear fractal dimension D( k) of R-R using the fractal dimension analysis. We find: 1) No significant difference in ( P > 0.05); 2) a significant difference in σR-Rand σΔR-Rfor the Fantasia groups ( P < 10−4) but no significant change with age between the elderly SHHS groups ( P > 0.5); and 3) no significant change in the fractal measures αR-R( P > 0.15), αsgn( P > 0.2), αmag( P > 0.3), and D( k) with age. Our findings do not support the hypothesis that fractal linear and nonlinear characteristics of heart beat dynamics break down with advanced age in healthy subjects. Although our results indeed show a reduced SD of heart beat fluctuations with advanced age, the inherent temporal fractal and nonlinear organization of these fluctuations remains stable. This indicates that the coupled cascade of nonlinear feedback loops, which are believed to underlie cardiac neuroautonomic regulation, remains intact with advanced age.
Experimental dissociation of neural circuits underlying conditioned avoidance and hypophagic responses to lithium chloride
Authors: Rinaman Linda , Dzmura Victoria
Published: August 2007

We previously reported that noradrenergic (NA) neurons in the nucleus of the solitary tract (NST) are necessary for exogenous CCK octapeptide to inhibit food intake in rats. To determine whether NST NA neurons also are necessary for lithium chloride (LiCl) to inhibit food intake and/or to support conditioned avoidance behavior, saporin toxin conjugated to an antibody against dopamine beta hydroxylase (DSAP) was microinjected bilaterally into the NST to ablate resident NA neurons. DSAP and sham control rats subsequently were tested for the ability of LiCl (0.15M, 2% body wt) to inhibit food intake and to support conditioned flavor avoidance (CFA). LiCl-induced hypophagia was significantly blunted in DSAP rats, and those with the most extensive loss of NST NA neurons demonstrated the most attenuated LiCl-induced hypophagia. Conversely, LiCl supported a robust CFA that was of similar magnitude in sham control and DSAP rats, including rats with the most extensive NA lesions. A terminal c-Fos study revealed intact LiCl-induced c-Fos expression in the lateral parabrachial nucleus and central amygdala in DSAP rats, despite significant loss of NST NA neurons and attenuated c-Fos activation of corticotropin-releasing hormone-positive neurons in the paraventricular nucleus of the hypothalamus (PVN). Thus, NST NA neurons contribute significantly to LiCl-induced hypophagia and recruitment of stress-responsive PVN neurons but appear to be unnecessary for CFA learning and expression. These findings support the view that distinct central nervous system circuits underlie LiCl-induced inhibition of food intake and conditioned avoidance behavior in rats.
Characterization of a long-term rat mTAL cell line
Authors: Eng Ben , Mukhopadhyay Somshuvra , Vio Carlos P. , Pedraza Paulina L. , Hao Shoujin , Battula Sailaja , Sehgal Pravin B. , McGiff John C. , Ferreri Nicholas R.
Published: August 2007

A medullary thick ascending limb (mTAL) cell line, termed raTAL, has been established from freshly isolated rat mTAL tubules and cultured continuously for up to 75 passages; it retains characteristics of mTAL cells even after retrieval from storage in liquid nitrogen for several months. The cells express Tamm-Horsfall glycoprotein (THP), a TAL-specific marker, grow to confluence, exhibit a polygonal morphology characteristic of epithelial cells, and form “domes.” Detection of THP, Na+-K+-2Cl−cotransporter (NKCC2), Na+-K+-ATPase, and renal outer medullary K+channel (ROMK) was achieved using indirect immunofluorescence and confocal microscopy. Western blot analysis of NKCC2 expression using two different antibodies revealed a band of ∼160 kDa, and RT-PCR analysis demonstrated the presence of NKCC2 isoforms A and F, which was confirmed by DNA sequencing; transport of Cl−into raTAL cells was inhibited by furosemide. Ouabain- and bumetanide-sensitive oxygen consumption, an index of ion transport activity in the mTAL, was observed in raTAL cells, and the number of domes present was reduced significantly when cells were incubated in the presence of ouabain or bumetanide. The specific activity of Na+-K+-ATPase activity was determined in raTAL cells (0.67 ± 0.18 nmol Pi·μg protein−1·min−1), primary cultures of mTAL cells (0.39 ± 0.08 nmol Pi·μg protein−1·min−1), and freshly isolated mTAL tubules (1.10 ± 0.29 nmol Pi·μg protein−1·min−1), and ∼30–50% of total cellular ATPase activity was inhibited by ouabain, in accord with other mTAL preparations. This cell line will be used in studies that address biochemical, molecular, and physiological mechanisms in the mTAL.
Role of Precise Spike Timing in Coding of Dynamic Vibrissa Stimuli in Somatosensory Thalamus
Authors: Montemurro Marcelo A. , Panzeri Stefano , Maravall Miguel , Alenda Andrea , Bale Michael R. , Brambilla Marco , Petersen Rasmus S.
Published: August 2007

Rats discriminate texture by whisking their vibrissae across the surfaces of objects. This process induces corresponding vibrissa vibrations, which must be accurately represented by neurons in the somatosensory pathway. In this study, we investigated the neural code for vibrissa motion in the ventroposterior medial (VPm) nucleus of the thalamus by single-unit recording. We found that neurons conveyed a great deal of information (up to 77.9 bits/s) about vibrissa dynamics. The key was precise spike timing, which typically varied by less than a millisecond from trial to trial. The neural code was sparse, the average spike being remarkably informative (5.8 bits/spike). This implies that as few as four VPm spikes, coding independent information, might reliably differentiate between 106 textures. To probe the mechanism of information transmission, we compared the role of time-varying firing rate to that of temporally correlated spike patterns in two ways: 93.9% of the information encoded by a neuron could be accounted for by a hypothetical neuron with the same time-dependent firing rate but no correlations between spikes; moreover, ≥93.4% of the information in the spike trains could be decoded even if temporal correlations were ignored. Taken together, these results suggest that the essence of the VPm code for vibrissa motion is firing rate modulation on a submillisecond timescale. The significance of such a code may be that it enables a small number of neurons, firing only few spikes, to convey distinctions between very many different textures to the barrel cortex.
Response Properties of Neighboring Neurons in the Auditory Midbrain for Pure-Tone Stimulation: A Tetrode Study
Authors: Seshagiri Chandran V. , Delgutte Bertrand
Published: August 2007

The complex anatomical structure of the central nucleus of the inferior colliculus (ICC), the principal auditory nucleus in the midbrain, may provide the basis for functional organization of auditory information. To investigate this organization, we used tetrodes to record from neighboring neurons in the ICC of anesthetized cats and studied the similarity and difference among the responses of these neurons to pure-tone stimuli using widely used physiological characterizations. Consistent with the tonotopic arrangement of neurons in the ICC and reports of a threshold map, we found a high degree of correlation in the best frequencies (BFs) of neighboring neurons, which were mostly <3 kHz in our sample, and the pure-tone thresholds among neighboring neurons. However, width of frequency tuning, shapes of the frequency response areas, and temporal discharge patterns showed little or no correlation among neighboring neurons. Because the BF and threshold are measured at levels near the threshold and the characteristic frequency (CF), neighboring neurons may receive similar primary inputs tuned to their CF; however, at higher levels, additional inputs from other frequency channels may be recruited, introducing greater variability in the responses. There was also no correlation among neighboring neurons' sensitivity to interaural time differences (ITD) measured with binaural beats. However, the characteristic phases (CPs) of neighboring neurons revealed a significant correlation. Because the CP is related to the neural mechanisms generating the ITD sensitivity, this result is consistent with segregation of inputs to the ICC from the lateral and medial superior olives.
From Politik als Beruf to Politics as a Vocation
Authors: Borchert Jens
Published: August 2007

Max Weber's 1919 lecture Politik als Beruf is still considered a classical text in the social sciences. The reception of the text in the Anglo-Saxon world has been profoundly shaped by the translation provided by Hans H. Gerth and C. Wright Mills, first appearing in 1946. Their Politics as a Vocation is more than a vivid transposition of Weber's rather peculiar German rhetoric—it is rendered in a way that suggests a certain interpretation and makes others highly improbable. The present article traces the reception of Weber's text back to certain decisions made by the translators after World War II. It argues that the translation emphasized philosophical and ethical parts of the text at the expense of others that were more geared toward a political sociology of modern politics. Moreover, the adoption of Weber's approach in empirical research was hindered if not foreclosed by a distorted presentation of his key typologies and some central concepts.
Corrigendum
Authors: Tilmans Karin
Published: August 2007

The article “Applying Begriffsgeschichte to Dutch History: Some Remarks on the Practice and Future of a Project” (Contributions to the History of Concepts, vol. 2, no. 1, March 2006, pp. 43-58) is based on a collective paper Wyger Velema and I wrote for the first HSPCG conference held at the Finnish Institute in London, June 1998. It contains therefore substantive parts written by him, and as this is not at all clear from the published article, I would very much herewith like to rectify this and apologize for any inconvenience caused.
A Zonal Momentum Balance on Density Layers for the Central and Eastern Equatorial Pacific
Authors: Brown Jaclyn N. , Godfrey J. Stuart , Fiedler Russell
Published: August 2007

Brown et al. analyzed the kinematics of flow in the equatorial Pacific Ocean, along time-varying isopycnals in a three-dimensional eddy-permitting model. Here the dynamics of these flows is explored in the same model via the zonal momentum equation (ZME). Previous work has shown that the dominant terms of the ZME, on and near the equator, are the pressure gradient, wind stress, and Coriolis term. In one model study, the nonlinear and friction terms were significant but negated each other. In this study, with a higher-resolution model and more realistic friction scheme it is shown that the nonlinear term is important along and north of the equator, while the explicit friction term is negligible. The part of the nonlinear term derived from high-frequency eddy flows acts like a friction on the Equatorial Undercurrent, while the remaining part of the nonlinear term from smooth flows enhances it. In density coordinates, meridional tropical cells lie on either side of the equator in the first half of the year (January–June) as expected. In July–December, a continuous southward surface flow appears from 4°N into the Southern Hemisphere and arises from variations in the geostrophic flow and the nonlinear term. Variations in the geostrophic flow are due to both seasonal variability in the thermocline and a surface bolus effect arising from baroclinic instability. The nonlinear term increases in the surface layers at the same time assisting the southward flow, most likely because of tropical instability waves.
Dissipative Losses in Nonlinear Internal Waves Propagating across the Continental Shelf
Authors: Moum J. N. , Farmer D. M. , Shroyer E. L. , Smyth W. D. , Armi L.
Published: August 2007

A single nonlinear internal wave tracked more than 100 wavelengths across Oregon’s continental shelf over a 12-h period exhibited nearly constant wave speed, c = 0.75 m s−1, and amplitude, a = 15 m. The wavelength L gradually decreased from 220 m in 170-m water depth to 60 m in 70-m water depth. As the water shallowed beyond 50 m, the wave became unrecognizable as such. The total energy decreased from 1.1 to 0.5 MJ m−1. The rate at which wave energy was lost, −dE/dt = 14 [7, 22] W m−1, was approximately equal to the energy lost to turbulence dissipation, ρɛ = 10 [7, 14] W m−1, as inferred from turbulence measurements in the wave cores plus estimates in the wave-induced bottom boundary layer. The approximate balance, dE/dt = −ρɛ, differs from the solibore model of Henyey and Hoering in which the potential energy across the wave balances ρɛ. However, other evidence suggests that the wave evolved from a solibore-like state to a dissipative solitary wavelike state over the observed propagation path.
Self-Regulation and Conduct Problems Among Low-Income African American Youth From Single-Mother Homes: The Roles of Perceived Neighborhood Context and Child Gender
Authors: Zalot Alecia A. , Jones Deborah J. , Forehand Rex , Brody Gene
Published: August 2007

The present study examines perceived neighborhood context and gender as moderators of the relation between self-regulation and conduct problems among low-income African American youth (7 to 15 years old; 50% girls) from single-mother homes. Mother-child dyads (N = 277) provided ratings of self-regulation, neighborhood resources and risks, and aggression and other conduct problems. Analyses revealed a significant three-way interaction among self-regulation, neighborhood context, and gender. Neighborhoods lower in resources and higher in risks exacerbated the link between poor self-regulation and aggression and conduct problems for girls, but not for boys. Clinical implications of the findings and future research directions are discussed.
Musical distracters, personality type and cognitive performance in school children
Authors: Furnham Adrian , Stephenson Rebecca
Published: August 2007

The aim of this study was to ascertain the nature of the interaction between the affective value of musical distraction, personality type and performance on the cognitive tasks of reading comprehension, free recall, mental arithmetic and verbal reasoning in children aged 11—12 years. It was hypothesized that the cognitive performance of extraverts would be signifcantly poorer when in the presence of background music that has a negatively affective value than when in the presence of background music that has a positively affective value. It was predicted that the converse of this would be true of introverts and neurotic personality types. Although few signifcant results were found in support of the central hypothesis, several results supported theoretical assumptions and showed clear trends that warrant further investigation. Limitations of this study and both experimental and interpretational problems in this area are discussed.
Context specificity in music perception of musicians
Authors: Madsen Clifford K. , Geringer John M. , Wagner Michael J.
Published: August 2007

Regardless of the extremely subtle acoustic changes that are perceptible within almost all perception research studies, it is the total overall effect that generally occupies each individual listener. A long line of research indicates that many subtle `music changes' are often not perceived accurately and are actually mistakenly identified. Another line of research indicates that almost everyone is capable of discriminating extremely small acoustic alterations if directed to do so. This study investigated spliced versions of Johann Strauss's Blue Danube Waltz all performed by the Vienna Philharmonic Orchestra with five different conductors demonstrating a wide range of conducting styles recorded across an 18-year period. Four groups of musicians ( N = 108) participated in the study: (1) video-only; (2) audio-video combination; (3) audio-only with verbal cues asking whether there were different conductors, ensembles, or compositions; and (4) audio-only without cues. Results indicated that while several of the audio-only with cues participants indicated differences in conductors, none in the non-cued group did. Not one of the music major participants in the two audio-only groups correctly identified that the stimulus had five different conductors.
The effects of altering environmental and instrumental context on the performance of memorized music
Authors: Mishra Jennifer , Backlin Willia M
Published: August 2007

Three experiments investigated whether musical memory was context dependent. Instrumental musicians memorized music in one context and recalled in either the same or a different context. Contexts included atypical performing environments (Experiment 1: lobby/conference room) or commonly encountered environments (Experiment 2: practice room, professor's studio, stage). Experiment 3 extended the definition of `context' to include instrument. Pianists memorized and recalled on either a grand piano or an upright. In Experiment 2, memory was not significantly different when the learning environment was altered; however, significant context effects were found in Experiments 1 and 3. A memory preference for the one context was discovered in Experiment 1, while in Experiment 3, musicians who memorized and performed on the same piano recalled significantly more than musicians who changed pianos. Some evidence exists for context effects in music; altering the environment at performance may lead to retrieval failure.
The Social Complexity of Organizational Learning: The Dynamics of Learning and Organizing
Authors: Antonacopoulou Elena , Chiva Ricardo
Published: August 2007

This article examines the social complexity of Organizational Learning. We built on and seek to extend recent conceptualizations of Organizational Learning that emphasize the emergent and fluid nature of learning in organizations, by drawing on some of the principles of Complexity Science. We selectively introduce two sets of principles of complexity that provide further richness to our understanding of Organizational Learning as a social complex process. The two sets of principles are `schemas—diversity' and `interaction—interdependence'. We discuss the main characteristics of these principles of Complexity Science and show they can help us understand aspects of the social complexity of Organizational Learning. Our analysis shows that one of the main contributions of the Complexity Science perspective to understanding Organizational Learning is that it reveals more clearly the tensions that underpin learning in social contexts. We provide a re-conceptualization of tensions as revealing elasticity and not only conflict. We argue that Organizational Learning as a source of tensions keeps the organization in tension, which allows us to better capture the dynamics of learning and organizing. We conclude by outlining some issues that future OL research would address if OL is conceptualized as a dynamic complex process.
Conversion between non-isothermal and isothermal transformation kinetics of γ to α for C–Mn and Nb microalloyed steels
Authors: Jia T. , Liu Z. Y. , Yuan X. Q. , Liu X. H. , Wang G. D.
Published: August 2007

In the present paper, austenite γ to ferrite α transformation kinetics of steels at different cooling rates has been measured by thermal dilatation. The relationship between lnln[1/(1 − X)] and ln(| CR|) ( CR: cooling rate) was plotted using the data at early stage of cooling, which well fitted a linear relationship for the calculation of exponential values of n in the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation for isothermal kinetics using the method developed by Rios. The values of k in the JMAK equation obtained with the Rios method, however, have led to big discrepancies when the isothermal equations were used to predict the transformation kinetics during cooling. By assuming a Gaussian function of temperature, k was calculated using an optimisation method based on the rule of additivity. The isothermal transformation model was used to predict the transformation kinetics during cooling, showing good agreement with the measured data. It has been proved that even though the rule of additivity has to be relaxed to take into account the effects of cooling rates, precise conversion between non-isothermal and isothermal kinetics can still be realised.
Piercing/extrusion and FSW nugget microstructure formation in Al alloys
Authors: McQueen H. J. , Cabibbo M. , Evangelista E.
Published: August 2007

Friction stir welding generates complex microstructures in the nugget and thermomechamically affected zones that have led to diverse explanations. Consideration as an extension of microstructure development in piercing/extrusion can lead to a better understanding of flow patterns and microstructures during friction stir welding. The nugget, thermomechanically affected and heat affected zones were microstructurally characterised in terms of grain and cell structures and of strain, strain rate and temperatures. The microstructure between the advancing and retreating zones showed an asymmetry in size and shape of grains and cells, clearly owing to a different level of strain rate to which were subjected the two zone as the pin passed.
Characterisation of FR-4 substrate with various plasma treatment conditions
Authors: Noh B.-I. , Jung S.-B.
Published: August 2007

The effects of plasma treatment on the surface of the flame resistant-4 (FR-4) substrate with underfills under various treatment conditions (operating gas, operating time, operating power) are investigated by using contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The plasma treatment on substrate surfaces increased the oxygen containing functional groups or the polar component of the surface free energy, improving the wetting characteristics of the underfills/FR-4 substrates. The plasma treatment conditions which minimised the contact angle between the underfills and FR-4 substrates were an operating power of 300 W and operating time of 180 s under Ar gas atmosphere.
Division of character zones and elements distribution of Fe3Al/Cr–Ni alloy fusion bonded joint
Authors: Ma H. J. , Li Y. J. , Li J. N. , Wang J.
Published: August 2007

A Fe3Al/Cr–Ni alloy fusion bonded joint was divided into four character zones of a homogeneous mixture zone, a partial mixture zone, a partially fused zone and a heat affected zone. The microstructures, elements distribution and phase constitutions of the various character zones were analysed via metalloscope, SEM, electron probe microanalysis and X-ray diffraction. The results indicated that the microstructures were dissimilar in the different character zones. A 0·04–0·05 mm austenite rich band existed in the partial mixture zone. The diffusion of Fe, Al, Cr, Ni and C mainly occurred in fusion zone where Cr and Ni diffused into Fe3Al to substitute some Fe on α1, α2, and β sublattices to form substitutional solid solution. The phase constitutions of Fe3Al/Cr–Ni joint were Fe3Al, γ-Fe, FeAl, NiAl, an unidentified Fe–C compound and an Fe–Cr–C compound (Cr9Fe)7C3.
Investigation of radiation damage to microcapsules in environmental SEM
Authors: Ren Y. L. , Donald A. M. , Zhang Z. B.
Published: August 2007

The radiation damage to a specimen in the chamber of electron microscopes has been studied extensively in the past few years. However, for the specific case of specimens with a core/shell structure, such as microcapsules and biological cells, there has been little experimentation devoted to understanding how the radiation may affect their mechanical properties. In the present work, single melamine formaldehyde (MF) microcapsules were imaged using an environmental electron microscope (ESEM) under both dry and wet modes under conditions of different accelerating voltages. The changes in the morphology (shape) were monitored as a function of radiation time. In addition, a newly developed ESEM based nanomanipulation technique was used to measure how the force imposed on single MF microcapsules for a given deformation changed with radiation time, in order to identify a time window within which the radiation damage to the microcapsules may be negligible in order to be able to study the mechanical properties of the particles. Based on the findings, the nanomanipulation technique was applied to measure the force versus displacement for compressing single microcapsules to rupture, including determination of their rupture mode.
Improved properties of SrFe12O19 synthesised by gel self-propagating combustion technique with glycol as solvent
Authors: Pan X. F. , Mu G. H. , Chen N. , Gan K. K. , Yang K. , Gu M. Y.
Published: August 2007

In this work SrFe12O19 is synthesised by gel self-propagating combustion technique with glycol as solvent. The morphology, crystal structure and magnetic properties of the as fabricated powders are investigated with X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis/differential scanning calorimetry and vibrating sample magnetometry. The results show that the coercivity and specific saturation magnetisation of the as fabricated SrFe12O19 are increased to 528 kA m−1 and 59·6 EMU g−1, in comparison with 404 kA m−1 and 57·6 EMU g−1 using water as solvent. The 528 kA m−1 is the highest Hc value recorded for isotropic SrFe12O19.
Effects of dilution on microstructure and wear behaviour of NiCr hardface deposits
Authors: Das C. R. , Albert S. K. , Bhaduri A. K. , Nithya R.
Published: August 2007

The effect of dilution on the microstructure, hardness and wear properties of two nickel base NiCr hardfacing alloys deposited using the gas tungsten arc welding (GTAW) process has been studied. Dilution from the base metal altered the microstructure, volume fraction and type of precipitates in the deposit, all of which varied with the distance from the deposit/substrate interface. The microstructural variation in the deposit was accompanied by corresponding variation in the deposit hardness. A pin on disc wear test, carried out using pins with varying thickness of deposit, showed that the wear resistance of the deposit increased with increasing thickness of the deposit, indicating that the wear resistance decreases with increasing dilution from the base metal. The present study brings out the effect of dilution from the substrate material on the properties of NiCr hardface deposits and the need to ensure a minimum thickness of GTAW deposits of these hardfacing alloys for obtaining the desired wear resistance.
Synthesis of TiB2 metal matrix composite on plain steel substrate: Microstructure and wear properties
Authors: Darabara M. , Papadimitriou G. D. , Bourithis L.
Published: August 2007

Metal matrix composites (MMC) synthesised on steel or on titanium substrates can be used in industry for parts demanding high wear resistance. In particular, TiB2 can be used as reinforcing material in MMCs due to its high melting point, high hardness and good wear and corrosion resistance. In the present paper, a titanium diboride composite is deposited on low carbon steel by the plasma transferred arc technique (PTA). Layers with ∼ 1 mm in thickness and 600 HV in hardness are obtained and their microstructure and wear resistance are studied. The wear rate of the alloyed layer against a tool steel counterbody is in the order of 10−5 mm3 m−1, while that for the alloyed layer against alumina is in the order of 10−4 mm3 m−1. The friction coefficient for the alloyed layer–tool steel system is 0·12 and for the alloyed layer–alumina system is 0·59. These differences in friction and wear behaviour are due to the different wear mechanisms of the corresponding tribosystems.
Resin transfer moulded silica fibre/phenolics composites fabricated via solution impregnation route
Authors: Wang B. C. , Huang Y. D. , Chen P. , Gao Y.
Published: August 2007

Silica fibre/phenolics composites produced by resin transfer moulding (RTM) solution impregnation technique are finding applications as aerospace structures. Typical phenolics contain solvent to facilitate injection and mould filling. It has been found that volatilisations of solvent and condensation polymerisation byproduct would cause void in cured composites, which is believed to affect the properties of the final product. In the present study, the role of solvent in the RTM impregnation process of silica fibre/phenolics composites was investigated. Experiments on wettability and flow were performed to evaluate the thermodynamical interaction on microscopic level occurring in fibre and resin system. Void content and interfacial strength were also examined. For the first time it has shown that the RTM process of silica fibre/phenolics composites is highly solvent dependent. Phenolics form distribution gradient in RTM mould with respect to isomeric composition under the effect of solvent, which results, to a varying extent, in the inhomogeneity of void content and thus interlaminar shear strength of the resulting product. The present work gives an insight into the role of organic solvent in RTM processing and this will help in choosing the best possible solvent for the solution impregnation system.
Simple model for carbonitride dissolution in microalloyed steels
Authors: Wang H. R. , Wang W.
Published: August 2007

Based on local equilibrium at the moving phase boundary and diffusion control a simple but comprehensive model concerning the carbonitride dissolution kinetics has been constructed. This model describes the evolution of a single particle or a distribution of particles in a finite austenite matrix with annealing temperature or time. It is shown that at temperatures below the dissolution temperature of carbonitrides the particle size decreases rapidly in early stages and then slows down approaching the equilibrium state. When the temperature, however, exceeds the dissolution temperature of precipitates the particles will be completely dissolved. The time evolution curves of particle size and volume fraction drop quickly and level off at certain temperatures. In contrast, the volume fraction and mean radius of precipitates decrease slowly first at lower temperatures and then drop drastically at higher temperatures. Finally the present model has been validated by the experimental data in the literature.
Target proteins of C/EBPαp30 in AML: C/EBPαp30 enhances sumoylation of C/EBPαp42 via up-regulation of Ubc9
Authors: Geletu Mulu , Balkhi Mumtaz Y. , Peer Zada Abdul A. , Christopeit Maximilian , Pulikkan John A. , Trivedi Arun K. , Tenen Daniel G. , Behre Gerhard
Published: August 2007

CCAAT/enhancer-binding protein α (C/EBPα) is a critical regulator for early myeloid differentiation. Mutations in C/EBPα occur in 10% of patients with acute myeloid leukemia (AML), leading to the expression of a 30-kDa dominant-negative isoform (C/EBPαp30). In the present study, using a global proteomics approach to identify the target proteins of C/EBPαp30, we show that Ubc9, an E2-conjugating enzyme essential for sumoylation, is increased in its expression when C/EBPαp30 is induced. We confirmed the increased expression of Ubc9 in patients with AML with C/EBPαp30 mutations compared with other subtypes. We further confirmed that the increase of Ubc9 expression was mediated through increased transcription. Furthermore, we show that Ubc9-mediated enhanced sumoylation of C/EBPαp42 decreases the transactivation capacity on a minimal C/EBPα promoter. Importantly, overexpression of C/EBPαp30 in granulocyte colony-stimulating factor (G-CSF)–stimulated human CD34+ cells leads to a differentiation block, which was overcome by the siRNA-mediated silencing of Ubc9. In summary, our data indicate that Ubc9 is an important C/EBPαp30 target through which C/EBPαp30 enhances the sumoylation of C/EBPαp42 to inhibit granulocytic differentiation.
A cis-regulatory logic simulator
Authors: Zeigler Robert D , Gertz Jason , Cohen Barak A
Published: August 2007

Background

A major goal of computational studies of gene regulation is to accurately predict the expression of genes based on the cis-regulatory content of their promoters. The development of computational methods to decode the interactions among cis-regulatory elements has been slow, in part, because it is difficult to know, without extensive experimental validation, whether a particular method identifies the correct cis-regulatory interactions that underlie a given set of expression data. There is an urgent need for test expression data in which the interactions among cis-regulatory sites that produce the data are known. The ability to rapidly generate such data sets would facilitate the development and comparison of computational methods that predict gene expression patterns from promoter sequence.

Results

We developed a gene expression simulator which generates expression data using user-defined interactions between cis-regulatory sites. The simulator can incorporate additive, cooperative, competitive, and synergistic interactions between regulatory elements. Constraints on the spacing, distance, and orientation of regulatory elements and their interactions may also be defined and Gaussian noise can be added to the expression values. The simulator allows for a data transformation that simulates the sigmoid shape of expression levels from real promoters. We found good agreement between sets of simulated promoters and predicted regulatory modules from real expression data. We present several data sets that may be useful for testing new methodologies for predicting gene expression from promoter sequence.

Conclusion

We developed a flexible gene expression simulator that rapidly generates large numbers of simulated promoters and their corresponding transcriptional output based on specified interactions between cis-regulatory sites. When appropriate rule sets are used, the data generated by our simulator faithfully reproduces experimentally derived data sets. We anticipate that using simulated gene expression data sets will facilitate the direct comparison of computational strategies to predict gene expression from promoter sequence. The source code is available online and as additional material. The test sets are available as additional material.
Molecular evolution of the MAGUK family in metazoan genomes
Authors: te Velthuis Aartjan JW , Admiraal Jeroen F , Bagowski Christoph P
Published: August 2007

Background

Development, differentiation and physiology of metazoans all depend on cell to cell communication and subsequent intracellular signal transduction. Often, these processes are orchestrated via sites of specialized cell-cell contact and involve receptors, adhesion molecules and scaffolding proteins. Several of these scaffolding proteins important for synaptic and cellular junctions belong to the large family of membrane-associated guanylate kinases (MAGUK). In order to elucidate the origin and the evolutionary history of the MAGUKs we investigated full-length cDNA, EST and genomic sequences of species in major phyla.

Results

Our results indicate that at least four of the seven MAGUK subfamilies were present in early metazoan lineages, such as Porifera. We employed domain sequence and structure based methods to infer a model for the evolutionary history of the MAGUKs. Notably, the phylogenetic trees for the guanylate kinase (GK)-, the PDZ- and the SH3-domains all suggested a matching evolutionary model which was further supported by molecular modeling of the 3D structures of different GK domains. We found no MAGUK in plants, fungi or other unicellular organisms, which suggests that the MAGUK core structure originated early in metazoan history.

Conclusion

In summary, we have characterized here the molecular and structural evolution of the large MAGUK family. Using the MAGUKs as an example, our results show that it is possible to derive a highly supported evolutionary model for important multidomain families by analyzing encoded protein domains. It further suggests that larger superfamilies encoded in the different genomes can be analyzed in a similar manner.
A high resolution radiation hybrid map of bovine chromosome 14 identifies scaffold rearrangement in the latest bovine assembly
Authors: Marques Elisa , de Givry Simon , Stothard Paul , Murdoch Brenda , Wang Zhiquan , Womack James , Moore Stephen S
Published: August 2007

Background

Radiation hybrid (RH) maps are considered to be a tool of choice for fine mapping closely linked loci, considering that the resolution of linkage maps is determined by the number of informative meiosis and recombination events which may require very large mapping populations. Accurately defining the marker order on chromosomes is crucial for correct identification of quantitative trait loci (QTL), haplotype map construction and refinement of candidate gene searches.

Results

A 12 k Radiation hybrid map of bovine chromosome 14 was constructed using 843 single nucleotide polymorphism markers. The resulting map was aligned with the latest version of the bovine assembly (Btau_3.1) as well as other previously published RH maps. The resulting map identified distinct regions on Bovine chromosome 14 where discrepancies between this RH map and the bovine assembly occur. A major region of discrepancy was found near the centromere involving the arrangement and order of the scaffolds from the assembly. The map further confirms previously published conserved synteny blocks with human chromosome 8. As well, it identifies an extra breakpoint and conserved synteny block previously undetected due to lower marker density. This conserved synteny block is in a region where markers between the RH map presented here and the latest sequence assembly are in very good agreement.

Conclusion

The increase of publicly available markers shifts the rate limiting step from marker discovery to the correct identification of their order for further use by the research community. This high resolution map of bovine chromosome 14 will facilitate identification of regions in the sequence assembly where additional information is required to resolve marker ordering.
cDNA sequences reveal considerable gene prediction inaccuracy in the Plasmodium falciparum genome
Authors: Lu Fangli , Jiang Hongying , Ding Jinhui , Mu Jianbing , Valenzuela Jesus G , Ribeiro José MC , Su Xin-zhuan
Published: August 2007

Background

The completion of the Plasmodium falciparum genome represents a milestone in malaria research. The genome sequence allows for the development of genome-wide approaches such as microarray and proteomics that will greatly facilitate our understanding of the parasite biology and accelerate new drug and vaccine development. Designing and application of these genome-wide assays, however, requires accurate information on gene prediction and genome annotation. Unfortunately, the genes in the parasite genome databases were mostly identified using computer software that could make some erroneous predictions.

Results

We aimed to obtain cDNA sequences to examine the accuracy of gene prediction in silico. We constructed cDNA libraries from mixed blood stages of P. falciparum parasite using the SMART cDNA library construction technique and generated 17332 high-quality expressed sequence tags (EST), including 2198 from primer-walking experiments. Assembly of our sequence tags produced 2548 contigs and 2671 singletons versus 5220 contigs and 5910 singletons when our EST were assembled with EST in public databases. Comparison of all the assembled EST/contigs with predicted CDS and genomic sequences in the PlasmoDB database identified 356 genes with predicted coding sequences fully covered by EST, including 85 genes (23.6%) with introns incorrectly predicted. Careful automatic software and manual alignments found an additional 308 genes that have introns different from those predicted, with 152 new introns discovered and 182 introns with sizes or locations different from those predicted. Alternative spliced and antisense transcripts were also detected. Matching cDNA to predicted genes also revealed silent chromosomal regions, mostly at subtelomere regions.

Conclusion

Our data indicated that approximately 24% of the genes in the current databases were predicted incorrectly, although some of these inaccuracies could represent alternatively spliced transcripts, and that more genes than currently predicted have one or more additional introns. It is therefore necessary to annotate the parasite genome with experimental data, although obtaining complete cDNA sequences from this parasite will be a formidable task due to the high AT nature of the genome. This study provides valuable information for genome annotation that will be critical for functional analyses.
Genome-wide analysis of ABA-responsive elements ABRE and CE3 reveals divergent patterns in Arabidopsis and rice
Authors: Gómez-Porras Judith L , Riaño-Pachón Diego Mauricio , Dreyer Ingo , Mayer Jorge E , Mueller-Roeber Bernd
Published: August 2007

Background

In plants, complex regulatory mechanisms are at the core of physiological and developmental processes. The phytohormone abscisic acid (ABA) is involved in the regulation of various such processes, including stomatal closure, seed and bud dormancy, and physiological responses to cold, drought and salinity stress. The underlying tissue or plant-wide control circuits often include combinatorial gene regulatory mechanisms and networks that we are only beginning to unravel with the help of new molecular tools. The increasing availability of genomic sequences and gene expression data enables us to dissect ABA regulatory mechanisms at the individual gene expression level. In this paper we used anin-silico-based approach directed towards genome-wide prediction and identification of specific features of ABA-responsive elements. In particular we analysed the genome-wide occurrence and positional arrangements of two well-described ABA-responsivecis-regulatory elements (CREs), ABRE and CE3, in thale cress (Arabidopsis thaliana) and rice (Oryza sativa).

Results

Our results show that Arabidopsis and rice use the ABA-responsive elements ABRE and CE3 distinctively. Earlier reports for various monocots have identified CE3 as a coupling element (CE) associated with ABRE. Surprisingly, we found that while ABRE is equally abundant in both species, CE3 is practically absent in Arabidopsis. ABRE-ABRE pairs are common in both genomes, suggesting that these can form functional ABA-responsive complexes (ABRCs) in Arabidopsis and rice. Furthermore, we detected distinct combinations, orientation patterns and DNA strand preferences of ABRE and CE3 motifs in rice gene promoters.

Conclusion

Our computational analyses revealed distinct recruitment patterns of ABA-responsive CREs in upstream sequences of Arabidopsis and rice. The apparent absence of CE3s in Arabidopsis suggests that another CE pairs with ABRE to establish a functional ABRC capable of interacting with transcription factors. Further studies will be needed to test whether the observed differences are extrapolatable to monocots and dicots in general, and to understand how they contribute to the fine-tuning of the hormonal response. The outcome of our investigation can now be used to direct future experimentation designed to further dissect the ABA-dependent regulatory networks.
Treatment of two postoperative endophthalmitis cases due to Aspergillus flavus and Scopulariopsis spp. with local and systemic antifungal therapy
Authors: Aydin Sayime , Ertugrul Bulent , Gultekin Berna , Uyar Guliz , Kir Erkin
Published: August 2007

Background

Endophthalmitis is the inflammatory response to invasion of the eye with bacteria or fungi. The incidence of endophthalmitis after cataract surgery varies between 0.072–0.13 percent. Treatment of endophthalmitis with fungal etiology is difficult.

Case Presentation

Case 1: A 71-year old male diabetic patient developed postoperative endophthalmitis due to Aspergillus flavus. The patient was treated with topical amphotericin B ophthalmic solution, intravenous (IV) liposomal amphotericin-B and caspofungin following vitrectomy.

Case 2: A 72-year old male cachectic patient developed postoperative endophthalmitis due to Scopulariopsis spp. The patient was treated with topical and IV voriconazole and caspofungin.

Conclusion

Aspergillus spp. are responsible of postoperative fungal endophthalmitis. Endophthalmitis caused by Scopulariopsis spp. is a very rare condition. The two cases were successfully treated with local and systemic antifungal therapy.