bluuebunny/crossref_metadata_2025 huggingface dataset:
On a micro‐macro transition for a poroelastic three‐component model
Authors: Albers B.
Published: July 2010

In this paper a macroscopic linear model is constructed which is intended to describe wave propagation processes in partially saturated soils under isothermal conditions. A porous medium consisting of a deformable skeleton and compressible pore fluids is investigated. The form of the partial stresses is an extension to the two‐component model of Biot. Additionally to the classical coupling between solid and fluid there appear coupling parameters between solid and gas and fluid and gas. Macroscopic material parameters have to be determined from their measurable microscopic counterparts either by a micro‐macro‐transition or using relations for the three‐component body by Santos, Douglas, and Corberó which are analogous to the Gassmann relations for saturated porous media. The transition is illustrated using the examples of oil‐water and air‐water‐mixtures in sandstone. Finally, a glance on the results of the application of the model to wave propagation is given.
Acute Myocardial Infarction With Simultaneous Involvement of Right Coronary Artery and Left Anterior Descending Artery: A Case Report
Authors: Lee Wen‐Hsien , Hsu Po‐Chao , Lin Tsung‐Hsien , Su Ho‐Ming , Lai Wen‐Ter , Sheu Sheng‐Hsiung
Published: July 2010

Acute myocardial infarction is usually caused by rupture of unstable plaque and involves a single coronary artery. Simultaneous occlusions of multiple coronary arteries in patients with ST elevation myocardial infarction are uncommon and lead to a fatal outcome. We report a 75‐year‐old male presenting with persistent chest pain complicated by ventricular fibrillation. After defibrillation and cardiopulmonary resuscitation, an emergency coronary angiogram showed total occlusion of the right coronary artery, and thrombus in the proximal left anterior descending artery. Both coronary arteries underwent successful balloon inflation and stenting. The patient finally survived under ventilatory support. This rare case suggests that aggressive reperfusion therapy and even mechanical support to improve poor clinical outcome are suggested in high risk patients with multivessel occlusions.
The potential for increasing the concentrations of micro-nutrients relevant to human nutrition in meat, milk and eggs
Authors: ROOKE J. A. , FLOCKHART J. F. , SPARKS N. H.
Published: July 2010

A possible outcome of policies designed to reduce obesity in the human population and to mitigate greenhouse gas (GHG) emissions may be a decrease in human consumption of livestock products. However, livestock products currently make substantial contributions to intakes of specific micro-nutrients. Therefore, the present review examines the potential for increasing micro-nutrient concentrations of milk, muscle meats and eggs by nutritional and genetic means. Of the trace elements, copper (Cu), iron (Fe) and zinc (Zn) concentrations were largely resistant to manipulation by dietary means, but iodine (I) and selenium (Se) could be readily manipulated. Similarly, whileα-tocopherol concentrations were readily manipulated, responses to dietary supplementation with retinol, folate and cobalamin were lower and riboflavin was resistant to dietary manipulation. There were differences between products in the ease with which composition could be manipulated: egg concentrations were most responsive followed by milk and muscle meats. However, livestock products with increased micro-nutrients concentrations can supply a substantial proportion of the daily reference nutrient intake.
On the retrograde propagation of critical thermal convection in a slowly rotating spherical shell
Authors: TAKEHIRO SHIN-ICHI
Published: July 2010

The retrograde propagation mechanism of critical thermal convection with a sectorial pattern emerging in a slowly rotating spherical shell is investigated through vorticity budget analysis. In the equatorial region, stretching and shrinking of the fluid columns in the direction of the axis of rotation due to the radial component of velocity causes retrograde propagation, whereas in the mid-latitudes, tilting of the radial component of planetary vorticity by the radial shear of the latitudinal component of velocity is dominant. The switching of the propagating direction from retrograde to prograde according to the increase in the rotation speed of the shell originates from the transition of the morphology of vortices from the ‘banana-shaped’ type due to the constraint of the spherical geometry to the columnar type due to the Taylor–Proudman constraint. The variation of the morphology of vortices reverses the tendency of stretching/shrinking of fluid columns accompanied by their cylindrically radial displacement.
Brazilian Abolitionism, Its Historiography, and the Uses of Political History
Authors: NEEDELL JEFFREY D.
Published: July 2010

Explanations of the Abolitionist movement's success in Brazil (1888) have, since the 1960s and 1970s, emphasised the movement's material context, its class nature, and the agency of the captives. These analyses have misunderstood and gradually ignored the movement's formal political history. Even the central role of urban political mobilisation is generally neglected; when it is addressed, it is crippled by lack of informed analysis of its articulation with formal politics and political history. It is time to recover the relationship between Afro-Brazilian agency and the politics of the elite. In this article this is illustrated by analysing two conjunctures critical to the Abolitionist movement: the rise and fall of the reformist Dantas cabinet in 1884–85, and the relationship between the reactionary Cotegipe cabinet (1885–88), the radicalisation of the movement, and the desperate reformism that led to the Golden Law of 13 May 1888.
Democracy without Parties? Some Lessons from Peru
Authors: CRABTREE JOHN
Published: July 2010

Thirty years on from Peru's return to democracy in 1980, the country's record with democratisation has been chequered. Not only was the process of ‘consolidation’ reversed in the 1990s under the Fujimori government, but the degree to which durable linkages have been established between state and society is very limited. More than in most countries of Latin America, the party system has failed to fulfil the representative role allotted to it in the literature, a role that cannot easily be assumed by other sorts of institution. It is therefore an important case study for those concerned with the more structural obstacles to the development of representative politics. The article seeks to look at some key issues affecting party development: the chimera of consolidation, the persistence of clientelism and patrimonialism, the interaction with social movements and the significance of political culture.
‘Virtuous war’ and the emergence ofjus post bellum
Authors: BANTA BENJAMIN R.
Published: July 2010

Scholars from various subfields have recognised a dangerous novelty for ethical thought on war in the combination of a detached, or virtual, technical ability to wage war and the ethical imperatives of human rights norms – deemed ‘virtuous war’. This article begins by discussing the contention that the just war tradition acts as the enabling discourse for virtuous war, and the further contention that the wars being enabled are paradoxically unjust. After assessing the validity of the virtuous war claim it is argued that the just war tradition's core ethical commitment not only remains the most sound starting point for thinking about the morality of war, but is a commitment that those in the virtuous war literature suggesting alternate ethical doctrines on war implicitly reject. It is contended, though, that the addition of a third pillar to the just war structure of cause and means criteria – a justice after war orjus post bellum– has arisen due to the virtuous war reality, and is necessary in order for the just war tradition to remain committed to its core ethical principle in a 21st century marked by virtuous war. Lastly, I present a brief sketch ofjus post belluminformed by the article's key claims.
Targeting physical activity and nutrition interventions towards mothers with young children: a review on components that contribute to attendance and effectiveness
Authors: Hartman Marieke A , Hosper Karen , Stronks Karien
Published: July 2010

Objective

To gain insight into intervention components targeted specifically to mothers of young children that may contribute to attendance and effectiveness on physical activity and healthy eating.

Design

Systematic literature searches were performed using MEDLINE, Embase and cited references. Articles were included if they evaluated the effectiveness of a lifestyle intervention to promote physical activity and/or healthy eating in an experimental design among mothers with young children (age 0–5 years). Data were extracted on study characteristics, intervention components targeted towards mothers with young children, attendance and effectiveness. Extracted data were analysed in a descriptive manner.

Results

Eleven articles describing twelve interventions met the inclusion criteria. Of the six studies that measured attendance, two reported high attendance. Embedding the intervention within routine visits to child health clinics seems to increase attendance. Three studies found significant effects on physical activity and three on healthy eating. Effective interventions directed at physical activity included components such as counselling on mother-specific barriers or community involvement in intervention development and implementation. One of the three interventions that effectively increased healthy eating had components targeted at mothers (i.e. used targeted motivational appeals).

Conclusions

The number of experimental intervention studies for promoting physical activity and healthy eating among new mothers is limited. However, useful first recommendations can be set for targeting interventions towards mothers, in particular for promoting attendance and physical activity. More insight is required about the need for targeting health promotion programmes at new mothers, especially of those directed at nutritional behaviour.
Quantification of Sample Thickness and In-Concentration of InGaAs Quantum Wells by Transmission Measurements in a Scanning Electron Microscope
Authors: Volkenandt T. , Müller E. , Hu D.Z. , Schaadt D.M. , Gerthsen D.
Published: July 2010

High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images of electron-transparent samples show dominant atomic number (Z-) contrast with a high lateral resolution. HAADF STEM at low electron energies <30 keV is applied in this work for quantitative composition analyses of InGaAs quantum wells. To determine the local composition, normalized experimental image intensities are compared with results of Monte Carlo simulations. For verification of the technique, InGaAs/GaAs quantum-well structures with known In concentration are used. Transmission electron microscopy samples with known thickness are prepared by the focused-ion-beam technique. The method can be extended to other material systems and is particularly promising for the analysis of materials that are sensitive toward knock-on damage.
Artifacts at the centre of routines: performing the material turn in routines theory
Authors: D'ADDERIO LUCIANA
Published: July 2010

Existing theories of organizational routines have generally had simplistic and extreme views of artifacts as fully deterministic or largely inconsequential. Artifacts have been treated as either too solid to be avoided, or too flexible to have an effect. This paper endeavours to improve our understanding of the influence of artifacts on routines dynamics by proposing a novel and deeper conceptualization of their mutual relationship. In drawing from recent advances in Routines and STS/Performativity Theory, the paper contributes to advancing our understanding of routines dynamics by bringing artifacts and materiality from the periphery to the very centre of routines and Routines Theory.
Auroral signatures of flow bursts released during magnetotail reconnection at Jupiter
Authors: Radioti A. , Grodent D. , Gérard J.‐C. , Bonfond B.
Published: July 2010

Recent studies based on Hubble Space Telescope (HST) data reported the presence of transient polar dawn spots in the Jovian auroral region and interpreted them as signatures of internally driven magnetic reconnection in the Jovian magnetotail. Even though an association of the polar dawn spots with the reconnection process has been suggested, it has not been yet investigated which part of the process and what mechanism powers these auroral emissions. In the present study, we examine the scenario that the auroral spots are triggered by the inward moving flow bursts released during magnetic reconnection at Jupiter. We base our analysis on a model adapted from the terrestrial case, according to which moving plasma flow burst is coupled with the ionosphere by field‐aligned currents, giving rise to auroral emissions. We estimate the upward field‐aligned current at the flank of the flow bursts, using in‐situ magnetic field measurements and we derive the auroral emitted power. We statistically study the observed emitted power of the polar dawn spots, based on HST data from 1998 to 2007, and we compare it with the emitted power derived according to the proposed scenario. Apart from the emitted power, other properties of the polar dawn spots such as their location, periodicity, duty cycle and multiplicity suggest that they are associated with the inward moving flow bursts released during magnetic reconnection in Jupiter's tail.
Asymmetries in Saturn's radiation belts
Authors: Paranicas C. , Mitchell D. G. , Krimigis S. M. , Carbary J. F. , Brandt P. C. , Turner F. S. , Roussos E. , Krupp N. , Kivelson M. G. , Khurana K. K. , Cooper J. F. , Armstrong T. P. , Burton M.
Published: July 2010

We present both energetic proton and electron data from the main radiation belts of Saturn. When organized by L shell and equatorial pitch angle, data from Cassini's Magnetospheric Imaging Instrument reveal proton radiation belts that are highly symmetric in local time. The energetic electron radiation belts are asymmetric in two principal ways. Using data from two close passes of the planet, we find for energies near a few MeV, electron intensity levels are different between noon and midnight. Furthermore, when Cassini was inbound to Saturn, electron fluxes dropped precipitously before the spacecraft reached the main rings. Outbound, electron fluxes returned to high levels when the spacecraft moved outward of the main rings. In this paper, we suggest that electron flux level asymmetries are due in part to the presence of local time stationary particles in Saturn's inner magnetosphere. We also consider possible mechanisms to account the drop off of electrons near the ring edge on the dayside.
Optical complexity in Long Island Sound and implications for coastal ocean color remote sensing
Authors: Aurin D. A. , Dierssen H. M. , Twardowski M. S. , Roesler C. S.
Published: July 2010

The optical properties of estuaries can vary considerably with the delivery of pigmented materials from surrounding watersheds and marine waters. In this study, optical properties sampled at 158 stations throughout the Long Island Sound (LIS) estuary between 2004 and 2007 show significant regional variability. Chlorophyll, total suspended matter, light absorption, and scattering are exceptionally high compared to other coastal data. Inherent optical properties and sea surface reflectances revealed at least two optical domains: a phytoplankton‐dominated regime in western LIS and New York Bight and a sediment‐dominated regime in central and eastern LIS. Multivariate ordination analysis identified clusters of stations conforming to these optical domains, as well as stations near the Hudson and Connecticut rivers representing optical end‐members in LIS characterized by high chromophoric dissolved material (CDM) and biomass (Hudson River) and high sediment loads (Connecticut River). However, winds, tides, and subtidal estuarine circulation redistribute optical constituents throughout the major basins of LIS and homogenize riverine influence. Ocean color parameters, used to define the spectral quality of optical constituents, such as the spectral slopes of particulate backscattering and CDM absorption, and the chlorophyll‐specific phytoplankton absorption did not cluster and are relatively constant throughout the region at all times of year. Therefore, variability in spectral reflectance in LIS is principally controlled by the relative magnitudes of the optical properties at each station rather than by significant differences in spectral quality of optically significant constituents. Consistency in these ocean color parameters minimizes the necessity for subregional or seasonal “tuning” of ocean color algorithms.
Mercury dynamics in relation to dissolved organic carbon concentration and quality during high flow events in three northeastern U.S. streams
Authors: Dittman Jason A. , Shanley James B. , Driscoll Charles T. , Aiken George R. , Chalmers Ann T. , Towse Janet E. , Selvendiran Pranesh
Published: July 2010

Mercury (Hg) contamination is widespread in remote areas of the northeastern United States. Forested uplands have accumulated a large reservoir of Hg in soil from decades of elevated anthropogenic deposition that can be released episodically to stream water during high flows. The objective of this study was to evaluate spatial and temporal variations in stream water Hg species and organic matter fractions over a range of hydrologic conditions in three forested upland watersheds (United States). Mercury and organic matter concentrations increased with discharge at all three sites; however, the partitioning of Hg fractions (dissolved versus particulate) differed among sites and seasons. Associated with increased discharge, flow paths shifted from mineral soil under base flow to upper soil horizons. As flow paths shifted, greater concentrations of dissolved organic carbon (DOC) richer in aromatic substances were flushed from upper soil horizons to stream water. The hydrophobic organic matter associated with humic material from upper soils appears to have had a greater capacity to bind Hg. Because of the strong correlation between Hg and DOC, we hypothesize that there was a concurrent shift in the source of Hg with DOC from lower mineral soil to upper soil horizons. Our study suggests that stream discharge is an effective predictor of dissolved total Hg flux.
Atmospheric mineral dust in dryland ecosystems: Applications of environmental magnetism
Authors: Reynolds Richard L. , Goldstein Harland L. , Miller Mark E.
Published: July 2010

Magnetic properties of shallow (<10‐cm depth), fine‐grained surficial sediments contrast greatly with those of immediately underlying bedrock across much of the dry American Southwest. At 26 study sites in fine‐grained (<63 μm) surficial sediments isolated from alluvial inputs, isothermal remanent magnetization (IRM; mean of 67 samples = 6.72 × 10−3 Am2 kg−1) is more than two orders of magnitude greater than that for underlying Paleozoic and Mesozoic sedimentary rocks. This contrast is mainly caused by the presence of silt‐size, titanium‐bearing magnetite particles in the surficial deposits and their absence in bedrock. Because of their size, composition, and isolated location, the magnetite particles represent a component of atmospheric dust likely deposited over the past few centuries. The positive correlation of sediment‐IRM values with amounts of potential plant nutrients reveals the importance of atmospheric dust to soil fertility over much of the American Southwest. Subsequent disturbance of landscapes, by domestic livestock grazing as an example, commonly results in wind erosion, which then depletes exposed surfaces of original aeolian magnetite and associated fine‐grained sediment. Declines in soil fertility and water‐holding capacity in these settings can be estimated in some field settings via decreases in magnetic susceptibility, relative to nearby undisturbed areas. Along gentle hillslope gradients of the Colorado Plateau, field measures for aeolian magnetite demonstrate that the redistribution of deposited atmospheric dust influences landscape‐level patterns in the distribution of invasive exotic plant species. Our results indicate that environmental magnetism has high potential for assessing the development and degradation of dry landscapes elsewhere.
Chemical composition of simulated Titan's midatmospheric aerosols
Authors: Jacovi R. , Laufer D. , Dimitrov V. , Bar‐Nun A.
Published: July 2010

A large fraction of the major unsaturated species (C2H2 C2H4, HCN, and HC3N) with mixing ratios of about 3 × 10−6, 10−7–10−8, 3 × 10−7, and 10−9–10−10 reside in Titan's atmosphere between 150 and 500 km (Vinatier et al., 2009; Coustenis et al., 2007) before they condense near the tropopause. A large flux of medium‐wavelength UV penetrates down to these levels, resulting in the polymerization of these unsaturated compounds and the formation of aerosols. We performed our experiments on aerosol formation at these altitudes where both abundances and solar UV flux are high, bearing in mind that additional photolysis occurs at both higher and lower altitudes. In the gas phase, C2H2 photolysis results in unsaturated C4 species that, on further addition of C2, form the cyclic benzene. These gas‐phase intermediates are consumed when an acetylene‐poor gas mixture is irradiated for a long time, giving rise to larger solid‐state species, mainly by addition of C2, followed by further cyclization. The largest species formed was the condensed 5‐ring benzpyrene, not the 7‐ring coronen molecule, which could have been detected there. Another fraction of the polymers consists of polyvinyl and vinyl acetylene chains, which are cross‐linked due to their labile π electrons and form an insoluble solid matrix. This explains the reduction of the C:H ratio from the condensed aromatics of 1.2 to the measured C:H = 1.013 ± 0.001 of the polymers.
Prevalence of salivary Streptococcus mutans in mothers and in their preschool children
Authors: Thorild I. , Lindau‐jonson B. , Twetman S.
Published: July 2010

Summary. Objectives. To establish the prevalence and possible relationship of oral Streptococcusmutans colonization in mother–child pairs.

Design and setting. An analytical cross‐sectional study was carried out at a well‐baby evaluation clinic held at the Public Dental Clinic, Varberg, Sweden.

Sample and methods. Two hundred preschool children, 100 of which were 18 months old and the remaining 100 were 3 years old, and their mothers attended the clinic. All mothers were interviewed and their children’s medical history, oral hygiene routines and dietary habits established. All children were clinically examined. The presence and level of S. mutans was estimated in the mother–child pairs with the aid of the Strip mutans chair‐side test.

Results. Nearly 50% of mothers exhibited high levels of salivary S. mutans, prevalence among the 18‐month‐ and 3‐year‐olds was 30% and 42%, respectively. A statistically significant (P < 0·01) mother–child relationship was found; a greater presence in mothers led to a higher number of children found harbouring the bacteria. Logistic regression analysis found that high maternal S. mutans levels (P < 0·001), daily sweet intake (P < 0·01) and sugary drinks in feeding bottles (P < 0·05) were significant factors for S. mutans colonization in children. Absence of daily toothbrushing and use of feeding bottles at night failed to fit into the model. Caries prevalence (initial and manifest decayed surfaces) was significantly related to S. mutans colonization (P < 0·01).

Conclusion. The results support the concept of vertical transmission (mother–child), emphasizing the importance of the dietary component, and justifying a primary preventive approach with targeted action directed at mothers with high levels of S. mutans colonization.
An Ibotenate‐Selective Metabotropic Glutamate Receptor: Mediates Protein Phosphorylation in Cultured Hippocampal Pyramidal Neurons
Authors: Scholz W. K.
Published: July 2010

Abstract: Previous results showed that within 30 s after glutamate stimulation of cultured rat hippocampal pyramidal neurons there occurred an elevation of Ca2+ and diacylglycerol, and the phosphorylation of three acidic protein kinase C substrates, i.e., an 87‐kDa protein known as myristoylated alanine‐rich C kinase substrate and a 120‐and a 48‐kDa protein. In addition, it was suggested that a metabotropic‐type glutamate receptor might be responsible for the phosphorylation observed. This work examines the ability of metabotropic and ionotropic glutamate receptor agonists to quickly activate phospholipases in 1.26 mM versus 50 nM extracellular Ca2+ by measuring the generation of inositol phosphates. NMDA, quisqualate, and trans‐(±)‐1‐amino‐1,3‐cyclopentanedicarboxylic acid did not stimulate the generation of inositol phosphates in the presence of normal or low extracellular Ca2+ in pyramidal neurons. Kainate stimulated the production of inositol phosphates in the presence of 1.26 mM extracellular Ca2+ but not in 50 nM extracellular Ca2+. Other than glutamate, only ibotenate was able to stimulate the generation of inositol phosphates in both normal and low extracellular Ca2+. The maximal response to ibotenate was approximately equal to that of glutamate, when pyramidal neurons were stimulated in 50 nM extracellular Ca2+. The generation of inositol phosphates by glutamate and ibotenate could be partially blocked (50–60% reduction) by pretreatment of neurons with pertussis toxin (250 ng/ml),‐suggesting that a GTP‐binding protein might be involved. In addition, ibotenate stimulated the immediate phosphorylation of the same three protein kinase C substrates as glutamate. The NMDA receptor blocker MK‐801 had no effect on this phosphorylation. These results suggest that the stimulation of phosphorylation in pyramidal neurons by glutamate occurs predominantly through the activation of an ibotenate‐selective metabotropic glutamate receptor.
Food Deprivation Protects the Rat Striatum Against Hypoxia‐Ischemia Despite High Extracellular Glutamate
Authors: Dijk S. N. , Gastel W. Krop‐van , Obrenovitch T. P. , Korf J.
Published: July 2010

Abstract: In a model that combines hypoxia with ischemia, the relationship between histological outcome, evoked rise in blood glucose, and striatal glutamate release was investigated in the 24‐h food‐deprived and normally fed rat. Food deprivation protected the dorsolateral striatum very effectively, as was shown with a silver stain. An on‐ line monitoring technique based on microdialysis showed that, in the protected condition, more glutamate was re‐ leased into the striatal extracellular space than in the com‐ promised condition. The possibility that the microdialysis results were influenced by a difference in shrinking of the extracellular space following food deprivation was ex‐ cluded by the measurements of whole‐tissue impedance. During the hypoxic‐ischemic challenge, blood glucose rose in normally fed rats, but was suppressed almost com‐ pletely after food deprivation. These results led us to con‐ clude that, in our model of hypoxia‐ischemia, the amount of glutamate released is not related directly to the extent of brain damage, but the increase in blood glucose may determine at least part of the brain damage.
Acute and Persistent Suppression of Preproenkephalin mRNA Expression in the Striatum Following Developmental Hypoxic‐Ischemic Injury
Authors: Burke Robert E. , Franklin Steven O. , Inturrisi Charles E.
Published: July 2010

Abstract: The striatum is vulnerable to hypoxic‐ischemic injury during development. In a rodent model of perinatal hypoxia‐ischemia, it has been shown that striatal neurons are not uniformly vulnerable. Cholinergic neurons and NADPH‐diaphorase‐positive neurons are relatively spared. However, it is unknown what classes of striatal neurons are relatively sensitive. One of the major classes of striatal neurons uses enkephalin as a neurotransmitter. We have studied the effect of early hypoxic‐ischemic injury on this class of neurons using a quantitative solution hybridization assay for preproenkephalin mRNA in conjunction with in situ hybridization. Hypoxia‐ischemia results in an early (up to 24 h) decrease in striatal preproenkephalin mRNA, which is shown by in situ hybridization to occur mainly in the dorsal portion of the striatum. By 14 days, whole striatal preproenkephalin mRNA and total enkephalin‐containing peptide levels are normal. However, at 14 days, in situ hybridization reveals that regions of complete preproenkephalin mRNA‐positive neuron loss remain in the dorsal region. Normal whole striatal levels are due to an up‐regulation of preproenkephalin mRNA expression in the ventrolateral region of the injured striatum. Given the important role that the enkephalin‐containing striatal efferent projection plays in regulating motor function, its relative loss may be important in the chronic disturbances of motor control observed in brain injury due to developmental hypoxic‐ischemic injury.
A Kinetic Analysis of 6‐[18F]Fluoro‐l‐Dihydroxyphenylalanine Metabolism in the Rat
Authors: Cumming Paul , Kuwabara Hiroto , Gjedde Albert
Published: July 2010

Abstract: A previous study of the metabolism of 6‐[18F]‐fluoro‐l‐3,4‐dihydroxyphenylalanine (FDOPA) in rats pretreated with carbidopa contained information amenable to kinetic analysis. Using these data, tracer transfer coefficients and metabolic rate constants were estimated. After intravenous injection, FDOPA in circulation was O‐methylated (kD0 = 0.055 min−1), and the metabolite (O‐methyl‐FDOPA) escaped from plasma with a rate constant (kM−1) of 0.01 min−1. The initial clearance of FDOPA to striatum (KD1) was 0.07 ml g−1 min−1, and the equilibrium distribution volume (VDe) was 0.67 ml g−1. The initial clearance of O‐methyl‐FDOPA to striatum (KM1) was 0.08 ml g−1 min−1, and the equilibrium distribution volume (VMe) was 0.75 ml g−1. The rate constant of FDOPA decarboxylation (kD3) was 0.17 min−1 in striatum. The elimination of 6‐[18F]fluorodopamine (FDA) from striatum suggested an apparent rate constant for monoamine oxidase activity (k′7) of 0.055 min−1. 6‐[18F]Fluorohomovanillic acid (FHVA) was formed from 6‐[18F]fluoro‐l‐3,4‐dihydroxyphenylacetic acid with a rate constant (k11) of 0.083 min−1, and FHVA was eliminated from striatum (k9) with a rate constant of 0.12 min−1. The steady‐state concentration ratios of FDA and its metabolites were shown to be functions of these rate constants.
Kinetic Evaluation of the Commonality Between the Site(s) of Action of Cocaine and Some Other Structurally Similar and Dissimilar Inhibitors of the Striatal Transporter for Dopamine
Authors: Meiergerd Susan M. , Schenk James O.
Published: July 2010

Abstract: The inhibition by cocaine of the apparent initial rate of the transport of striatal dopamine was compared with inhibitions produced by cocaethylene, benztropine, GBR‐12909, mazindol, and nomifensine. Rotating disk electrode voltammetry was used to measure the kinetically resolved, inwardly directed transport of dopamine in striatal suspensions. Evidence is presented that the primary site of action of cocaine may be at the external face of the transporter. Experiments to determine whether or not the other inhibitors bind to the same site as cocaine were conducted by comparing the inhibitions observed for each of the inhibitors alone with that observed when paired with cocaine. The resulting changes in the velocity of the transport of dopamine induced by the inhibitors were then fit to one of the previously developed models of inhibition by pairs of inhibitors affecting the kinetics of actively transporting systems: a single‐site model, a two‐site model in which the two binding sites for the inhibitors interact, and a two‐site model in which the two binding sites for the two inhibitors act independently. Cocaine inhibited the transport of dopamine competitively with its structural analogues, cocaethylene and benztropine. The structurally dissimilar inhibitor, GBR‐12909, was found also to be competitive with cocaine. In contrast, mazindol and nomifensine were found to bind to separate interactive sites when individually paired with cocaine. These results suggest that mazindol and nomifensine may interact with the kinetically active transporter for dopamine in a manner different from that of cocaine. Mazindol was tested and found to inhibit competitively the inward transport of dopamine into striatal suspensions. In contrast, our previous published findings show cocaine to be an uncompetitive inhibitor of the transport of striatal dopamine. These results suggest that cocaine inhibits inward transport of dopamine by reducing the intramembrane turnover of the transporter, whereas mazindol alters the kinetics of the recognition of dopamine by the transporter. Finally, the potential effects of these binding modes of inhibitors on synaptic chemical communication in dopaminergic systems were analyzed. The results of these analyses suggest that different effects on the extracellular concentrations of dopamine can result from the different patterns of inhibition, suggesting that different modulatory influences on pre‐ and postsynaptic receptor occupation can result from inhibition of the transport of dopamine.
Density of NMDA‐Coupled and Uncoupled 1‐[1‐(2‐[3H]Thienyl)cyclohexyl]piperidine Recognition Sites in the Brain and Spinal Cord: Differential Effects of NMDA Agonists and Antagonists
Authors: Kovács Katalin J. , Larson Alice A.
Published: July 2010

Abstract: Binding of 1‐[1‐(2‐[3H]thienyl)cyclohexyl]piperidine ([3H]TCP) to mouse brain and spinal cord membranes was studied using compounds selective for the NMDA‐coupled 1‐(1‐phenylcyclohexyl)piperidine (PCP) and/or σ recognition sites. In both tissues, [3H]TCP labeled two populations of binding sites. Density of the low‐affinity sites was approximately the same in both tissues, but the population of the high‐affinity [3H]TCP sites was three times bigger in the brain than in the spinal cord. Self‐ and cross‐displacement studies showed that the high‐affinity [3H]TCP binding sites could be identical with NMDA receptor‐coupled PCP sites, whereas the low‐affinity [3H]TCP sites may be associated with σ binding sites in both tissues. The NMDA‐coupled PCP sites labeled in the presence of 6.25 nM [3H]TCP constituted a much higher percentage of the total binding in the brain (75%) than in the spinal cord (44%). Consistent with this, reintroduction of glycine and glutamate significantly increased, but DA antagonists significantly inhibited [3H]TCP binding in the brain but not in the spinal cord. Together, these data suggest that a large component of [3H]TCP‐labeled binding sites in the spinal cord may be associated with σ but not the NMDA receptor‐coupled PCP sites.
Phosphorylation of DARPP‐32 Is Regulated by GABA in Rat Striatum and Substantia Nigra
Authors: Snyder Gretchen L. , Fisone Gilberto , Greengard Paul
Published: July 2010

Abstract: In the medium‐sized spiny neurons of the striatonigral pathway, a cascade of events involving the activation of dopamine D1 receptors, an increase in cyclic AMP, and activation of cyclic AMP‐dependent protein kinase causes the phosphorylation of DARPP‐32 on Thr34, converting DARPP‐32 into a powerful inhibitor of protein phosphatase‐1. In the present study, the incubation of striatal or substantia nigra slices with GABA also increased the phosphorylation of DARPP‐32 on Thr34. GABA did not significantly increase cyclic AMP levels in slices. The phosphorylation of DARPP‐32 by GABA was blocked in both brain regions by pretreatment of slices with the GABAA receptor antagonist, bicuculline, but not with the GABAB receptor antagonist, phaclofen. Moreover, the threonine phosphorylation of DARPP‐32 produced by maximally effective doses of either forskolin (in striatum) or l‐3,4‐dihydroxyphenylalanine (in substantia nigra) was increased further by GABA. The data are consistent with a model in which GABA increases the phosphorylation state of DARPP‐32 by inhibiting dephosphorylation of the protein by the calcium/calmodulin‐dependent protein phosphatase, calcineurin.
3‐Nitropropionic Acid Toxicity in the Striatum
Authors: Wüllner U. , Young A. B. , Penney J. B. , Beal M. F.
Published: July 2010

Abstract: We examined the effects of chronic systemic administration of the mitochondrial toxin 3‐nitropropionic acid (3‐NP) in doses ranging from 12 to 16 mg/kg/day for 30 days on striatal cytoarchitecture in rats. Administration of 3‐NP at a dose of 16 mg/kg/day resulted in large lesions with a central necrotic core that was depleted of both neurons and glia. Glial fibrillary acidic protein (GFAP) gene expression was decreased in the lesion core, whereas the tissue surrounding this area showed a massive increase in signal intensity. Enkephalin and substance P mRNA expression in the striatum showed dose‐dependent decreases following administration of 3‐NP. A substantial decrease occurred even in animals treated with 3‐NP at a dose of 12 mg/kg/day, in which there was little discernible neuronal loss and no increase in GFAP gene expression. In contrast to the decrease in enkephalin and substance P mRNA expression, somatostatin mRNA‐expressing neurons were largely preserved. There was no preferential loss of [3H]naloxone patches in the rat striatum following chronic administration of 3‐NP. In animals treated with 12–15 mg/kg/day neither the area nor binding density of the patches was changed. To study the effect of 3‐NP on N‐methyl‐d‐aspartate (NMDA)‐gated Ca2+ channels we used in vivo administration of [3H]MK‐801. Three hours after a single injection of 3‐NP at a dose of 30 mg/kg there was a three‐ to fivefold increase in [3H]MK‐801 binding in cortex and striatum as compared with saline‐treated animals, consistent with an activation of NMDA receptors.
Changes in the Solubility of Glial Fibrillary Acidic Protein After Ischemic Brain Damage in the Mouse
Authors: Fahrig Thomas
Published: July 2010

Abstract: In the present study, changes in the content of glial fibrillary acidic protein (GFAP) in mouse cortex were investigated at different time intervals after unilateral middle cerebral artery occlusion. The GFAP content was assessed semiquantitatively by ELISA and immunoblotting. GFAP immunoreactivity was determined for each animal separately in protein fractions obtained from the ipsilateral, lesioned cortex and the contralateral, unlesioned cortex. Changes in the GFAP content of the lesioned cortex with respect to that of the unlesioned cortex were calculated for each fraction individually. GFAP was detectable in all protein fractions with a significant amount recovered from the aqueous extracts. A pronounced increase in the GFAP content of the lesioned cortex was observed. As measured by ELISA, this increase was maximal 5 days after injury and significantly more pronounced for the soluble and the Triton X‐100‐soluble protein fractions (mean increase 7 days after lesion, 281.4 and 240.2%, respectively) than for the crude cytoskeletal fraction (mean increase, 153.3%). A small and transient increase in GFAP immunoreactivity was also found in all protein fractions prepared from the contralateral, unlesioned cortex. These results were confirmed by immunoblotting.
Preferential Induction by Stress of the N‐Methyl‐d‐Aspartate Recognition Domain in Discrete Structures of Rat Brain
Authors: Yoneda Yukio , Han Daiken , Ogita Kiyokazu
Published: July 2010

Abstract: Immobilization stress in water for 3 h was effective in inducing significant potentiation of [3H](+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo [a,d] cyclohepten‐5,10‐imine ([3H]MK‐801) binding 5 days after the stressful manipulation in rat hypothalamus and cerebellum when determined before equilibrium in the absence of any added agonists, in addition to resulting in marked reduction of rearing behaviors of animals. However, the stressful manipulation failed to modulate the [3H]MK‐801 binding in other central regions examined, and binding of either [3H]dl‐α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid or [3H]kainic acid was not significantly affected in all brain structures studied 5 days after the stress application. In contrast, the stressful procedures potentiated binding of both l‐[3H]glutamic ([3H]Glu) and [3H]dl‐(E)‐2‐amino‐4‐propyl‐5‐phosphono‐3‐pentenoic ([3H]CGP‐39653) acids in the hypothalamus and cerebellum 5 days later, without affecting binding of [3H]‐glycine and 5,7‐dichloro[3H]kynurenic acid. The systemic administration of corticosterone mimicked the stress manipulation at doses of 5–50 mg/kg in terms of inducing significant enhancement of binding of both [3H]Glu and [3H]CGP‐39653 in the hypothalamus and cerebellum when determined 5 days after the single administration. The translation inhibitor cycloheximide was effective in preventing the stress‐induced potentiation of [3H]Glu binding in the cerebellum, without altering that in the hypothalamus. Furthermore, the stressful handling significantly increased the densities of [3H]Glu binding sites in the hypothalamus and cerebellum, with the affinities being unchanged. These results suggest that stress may preferentially potentiate binding of radioligands to the N‐methyl‐d‐aspartate recognition domain through facilitation of de novo biosynthesis in rat hypothalamus and cerebellum.
Dexamethasone Increases Adrenalectomy‐Depressed Na+,K+‐ATPase mRNA and Ouabain Binding in Spinal Cord Ventral Horn
Authors: González Susana , Grillo Claudia , De Nicola Alejandro G. , Piroli Gerardo , Angulo Jesus , McEwen Bruce S. , De Nicola Alejandro F.
Published: July 2010

Abstract: The Na+,K+‐ATPase plays a key role in the regulation of ion fluxes and membrane repolarization in the CNS. We have studied glucocorticoid effects on biosynthesis of the Na+,K+‐ATPase and on ouabain binding in the ventral horn of the spinal cord using intact rats, adrenalectomized (ADX) rats, and ADX rats receiving dexamethasone (ADX + DEX) during 4 days. Cryostat sections from spinal cords were incubated with a 35S‐oligonucleotide coding for the α3‐subunit or a 3H‐cDNA coding for the β1‐subunit of the Na+,K+‐ATPase using in situ hybridization techniques. In ventral horn motoneurons, grain density per cell and grain density per area of some for both probes were slightly reduced in ADX rats but significantly increased in the ADX + DEX group, using ANOVA and the Bonferroni's test. Statistical analysis of frequency histograms of neuronal densities further indicated a significant shift to the right for intact rats compared with ADX rats for both probes. Concomitantly, [3H]ouabain binding to membrane preparations from ventral horns was reduced in ADX rats and restored to normal by DEX administration. No effect of adrenalectomy or DEX treatment was obtained in the dorsal horn. In conclusion, glucocorticoids positively modulate the mRNA for the α3‐subunit and the β1‐subunit of the Na+,K+‐ATPase and recover ouabain binding to normal values. The increments of the synthesis and activity of an enzyme affecting membrane repolarization and synaptic neurotransmission are consistent with the alleged stimulatory effect of glucocorticoids on spinal cord function.
In Vivo Neuronal Synthesis and Axonal Transport of Kunitz Protease Inhibitor (KPI)‐Containing Forms of the Amyloid Precursor Protein
Authors: Moya Kenneth L. , Confaloni AnnaMaria , Allinquant Bernadette
Published: July 2010

Abstract: We have shown previously that the amyloid precursor protein (APP) is synthesized in retinal ganglion cells and is rapidly transported down the axons, and that different molecular weight forms of the precursor have different developmental time courses. Some APP isoforms contain a Kunitz protease inhibitor (KPI) domain, and APP that lacks the KPI domain is considered the predominant isoform in neurons. We now show that, among the various rapidly transported APPs, a 140‐kDa isoform contains the KPI domain. This APP isoform is highly expressed in rapidly growing retinal axons, and it is also prominent in adult axon endings. This 140‐kDa KPI‐containing APP is highly sulfated compared with other axonally transported isoforms. These results show that APP with the KPI domain is a prominent isoform synthesized in neurons in vivo, and they suggest that the regulation of protease activity may be an important factor during the establishment of neuronal connections.
Cell Growth Suppression of Astrocytoma C6 Cells by Glial Fibrillary Acidic Protein cDNA Transfection
Authors: Toda Masahiro , Miura Masayuki , Asou Hiroaki , Toya Shigeo , Uyemura Keiichi
Published: July 2010

Abstract: The cellular functions of the intermediate filament family including glial fibrillary acidic protein (GFAP) are not well known yet beyond their roles as structural elements of cells. Expression of GFAP, which is specific in astrocytes and regulated developmentally, suggests its involvement in cell growth and differentiation of astrocytes. We transfected murine GFAP cDNA into a rat astrocytoma C6 cell line to assess the specific effect of GFAP on cells. Two stable GFAP‐transfected cell lines, GFC6‐5 and GFC6‐6, exhibited a series of morphological and growth characteristics that distinguish them from their counterparts, i.e., NeoC6 cells transfected only with the neomycin‐resistant gene, and native C6 cells. Both GFC6‐5 and GFC6‐6 cells showed elongated cell shapes with extended processes rich in GFAP, markedly suppressed cell growth, and decreased bromodeoxyuridine uptake. Western blot analysis revealed a remarkable increase of GFAP expression in GFC6‐5 and GFC6‐6 compared with that in NeoC6 and C6, in contrast to similar vimentin expression in all cell lines. The results indicate that the expression of GFAP has dramatic effects on cell morphology and cell growth suppression in C6 cells, suggesting that GFAP may function as a tumor suppressor in astrocytoma.
Characterization of Neuronal Amino Acid Transporters: Uptake of Nitric Oxide Synthase Inhibitors and Implication for Their Biological Effects
Authors: Schmidt Kurt , List Barbara M. , Klatt Peter , Mayer Bernd
Published: July 2010

Abstract: In the present study we investigated uptake of the nitric oxide (NO) synthase inhibitors NG‐methyl‐l‐arginine and NG‐nitro‐l‐arginine by the mouse neuroblastoma × rat glioma hybrid cell line NG108‐15. Uptake of NG‐methyl‐l‐arginine was characterized by biphasic kinetics (Km1 = 8 µmol/L, Vmax1 = 0.09 nmol × mg−1× min−1; Km2 = 229 µmol/L, Vmax2 = 2.9 nmol × mg−1× min−1) and was inhibited by basic but not by neutral amino acids. Uptake of NG‐nitro‐l‐arginine followed Michaelis‐Menten kinetics (Km = 265 µmol/L, Vmax = 12.8 ± 0.86 nmol × mg−1× min−1) and was selectively inhibited by aromatic and branched chain amino acids. Further characterization of the transport systems revealed that uptake of NG‐methyl‐l‐arginine is mediated by system y+, whereas systems L and T account for the transport of NG‐nitro‐l‐arginine. In agreement with these data on uptake of the inhibitors, l‐lysine and l‐ornithine antagonized the inhibitory effects of NG‐methyl‐l‐arginine on bradykinin‐induced intracellular cyclic GMP accumulation, whereas l‐tryptophan, l‐phenylalanine, and l‐leucine interfered with the effects of NG‐nitro‐l‐arginine. These data suggest that rates of uptake are limiting for the biological effects of NO synthase inhibitors.
Localization of Basic Fibroblast Growth Factor in Bovine Adrenal Chromaffin Cells
Authors: Bieger Sophie C. , Henkel A. W. , Unsicker K.
Published: July 2010

Abstract: We have investigated basic fibroblast growth factor (FGF‐2) localization in and release from isolated bovine adrenal chromaffin cells. In contrast to previous reports, we found no evidence of fibroblast growth factor (FGF) storage in catecholamine‐containing chromaffin granules. Subcellular fractionation studies did not show enrichment of FGF‐2 immunoreactivity in granules, and cholinergic stimulation failed to release FGF‐2 into the medium. Our results suggest that adrenal chromaffin cells resemble other FGF‐2‐synthesizing cell types with respect to FGF storage and secretion.