bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends and issues in delivery of integrated catchment scale river restoration: Lessons learned from a national river restoration survey within Scotland
Authors: Gilvear David J. , Casas‐Mulet Roser , Spray Chris J.
Published: July 2010

This paper provides data on the changing character of river restoration within one country within a single policy and legislative framework. The information gathered was based on web searches, meetings and questionnaire responses with organizations and individuals working as environmental policy developers, stakeholders and practitioners of catchment management and river restoration. The paper utilizes this information to explore generic issues promoting and constraining a move to integrated catchment scale river restoration. Catchment scale river restoration was defined as ‘any river restoration activity that singly, or in combination, restores natural catchment processes and a naturally functioning ecosystem and brings benefit or environmental services to the whole catchment and not just to the site of restoration’.

The river restoration project data compiled showed that the number of projects in Scotland is on a strong upward trajectory, but the number of catchment scale projects is still limited. The data also showed a trend towards a range of underpinning reasons for river restoration. Traditionally the reasons for river restoration in Scotland have been strongly fisheries focussed, with another key driver being biodiversity conservation. Sustainable flood management and climate change adaptation are seen as emerging drivers of river restoration. In terms of the individuals interviewed, most appreciated that river restoration can bring about multiple benefits and should be underpinned by a good understanding of catchment processes.

Our overall assertion based on our study is that unless there is a fundamental paradigm shift, a change in the nature and level of funding for river restoration and a single organization is given overall authority to direct river restoration. ‘business as usual’ will continue and the benefits of catchment scale river restoration will be limited. Copyright © 2010 John Wiley & Sons, Ltd.
Reactivity of Copper(I) Halides CuCl, CuI with Double Alkoxides MAl(iOPr)4 (M = Na, K)
Authors: Tomar Nobel , Ghanti Epsita , Nagarajan Rajamani
Published: July 2010

The heterogeneous reaction between CuX (X = Cl–, I–) with alkali metal double alkoxides MAl(iOPr)4 (M = Na, K) for the synthesis of CuI containing single source precursor has been studied. The orange colored precursor obtained showed strong absorption in the UV region (235 nm) and photo luminescence emission band at 450 nm, which evidenced the formation of an adduct between the reactants. Controlled hydrolysis and decomposition of the gel yielded delafossite structured CuAlO2 along with some CuO.
Rare Earth Metal Complexes Supported by Ancillary Imidazolin‐2‐iminato Ligands
Authors: Trambitas Alexandra G. , Panda Tarun K. , Tamm Matthias
Published: July 2010

The coordination chemistry of imidazolin‐2‐iminato ligands towards rare earth metal atoms is reviewed. The structural characterization of a large number of mono‐, bis‐ and tris(imidazolin‐2‐iminato) complexes – in most cases scandium, yttrium, gadolinium, and lutetium complexes – reveals almost exclusively the formation of mononuclear complexes with very short metal–nitrogen bonds, which confirms the ability of imidazolin‐2‐iminato ligands to efficiently act as imido‐type 2σ,4π‐electron donors. In particular, mono(imidazolin‐2‐iminato) metal dichlorides proved to be excellent starting materials for the introduction of alkyl, amido, cyclopentadienyl, cyclooctatetraenyl, and carboranyl ligands and also for the preparation of efficient pre‐catalysts for ring‐opening, hydroamination and hydrosilylation reactions, which allow to establish imidazolin‐2‐iminato ligands as novel valuable members of the growing family of ancillary ligands in organo rare earth metal and organolanthanide chemistry. In addition, the coordination chemistry of several imidazolin‐2‐imine‐hybrid ligands such as cyclopentadienyl‐imine and pincer‐type diimine ligands is described, and the structural characterization of the resulting complexes indicates that also neutral imidazolin‐2‐imines act as strong amido‐type donor ligands towards rare earth metal ions.
Bis(1,3‐dinitratoprop‐2‐yl) Nitramine, a New Sensitive Explosive Combining a Nitrate Ester with a Nitramine
Authors: Klapötke Thomas M. , Krumm Burkhard , Steemann F. Xaver , Umland Klaus‐Daniel
Published: July 2010

Nitro functionalized compounds comprise a large substance class and are the most popular explosive materials. Recent research furnished a solid energetic nitrate ester of potential interest. This work is concerned with the synthesis and characterization of novel aliphatic nitramine compounds with similar features.
Chromosome 21 non-disjunction and Down syndrome birth in an Indian cohort: analysis of incidence and aetiology from family linkage data
Authors: GHOSH SUJOY , BHAUMIK PRANAMI , GHOSH PRIYANKA , DEY SUBRATA KUMAR
Published: July 2010

We analysed the family linkage data obtained from short tandem repeat (STR) genotyping of 212 unrelated Indian families having a single Down syndrome (DS) baby each, in order to explore the incidence and aetiology of this human aneuploidy in our cohort. The estimated values of maternal meiotic I and meiotic II non-disjunction (NDJ) errors of chromosome 21 (Ch 21) were ~78 and ~22%, respectively. Within the paternal outcome group, about 47 and 53% were accounted for NDJ at meiosis I and meiosis II, respectively. We estimated only ~2% post-zygotic mitotic errors. The comparison of average age of conception between controls and DS-bearing mothers revealed a significant difference (P<0·001) with DS-bearing women were on an average older than controls and meiotic II non-disjoined mothers were oldest among meiotic outcome groups. Our linkage analysis suggested an overall reduction in recombination by more than 50% on meiotic I non-disjoined maternal Ch 21 with error prone to susceptible chiasma formation within the ~5·1 kbp segment near the telomeric end. We stratified meiotic I non-disjoined women in three age groups, viz. young (⩽28 years), middle (29–34 years) and old (⩾35 years) and found linear decrease in the frequency of achiasmate meiosis from the young to the old group. In contrary, a linear increase in the multiple chiasma frequency from the young to the old group was observed. Considering these results together, we propose that the risk factors for Ch 21 NDJ are of two types, one being ‘maternal age-independent’ and the other being ‘maternal age-dependent’. Moreover, a comparison of our present Indian dataset with that of other published data of ethnically different populations suggested that the genetics that underlies the NDJ of Ch 21 is probably universal irrespective of racial difference across human populations. The present study is the first population-based report on any DS cohort from the Indian subcontinent and our work will help future workers in understanding better the aetiology of this birth defect.
Structures of membrane proteins
Authors: Vinothkumar Kutti R. , Henderson Richard
Published: July 2010

In reviewing the structures of membrane proteins determined up to the end of 2009, we present in words and pictures the most informative examples from each family. We group the structures together according to their function and architecture to provide an overview of the major principles and variations on the most common themes. The first structures, determined 20 years ago, were those of naturally abundant proteins with limited conformational variability, and each membrane protein structure determined was a major landmark. With the advent of complete genome sequences and efficient expression systems, there has been an explosion in the rate of membrane protein structure determination, with many classes represented. New structures are published every month and more than 150 unique membrane protein structures have been determined. This review analyses the reasons for this success, discusses the challenges that still lie ahead, and presents a concise summary of the key achievements with illustrated examples selected from each class.
South‐north asymmetry of field‐aligned currents in the magnetotail observed by Cluster
Authors: Shi J. K. , Cheng Z. W. , Zhang T. L. , Dunlop M. , Liu Z. X. , Torkar K. , Fazakerley A. , Lucek E. , Rème H. , Dandouras I. , Lui A. T. Y. , Pu Z. Y. , Walsh A. P. , Volwerk M. , Lahiff A. D. , Taylor M. G. G. T. , Grocott A. , Kistler L. M. , Lester M. , Mouikis C. , Shen C.
Published: July 2010

We statistically investigated features of the field‐aligned current (FAC) distribution in plasma sheet boundary layers between 17 and 19 RE in the magnetotail using the curlometer technique to calculate the current from four‐point magnetic field measurements taken in 2001. The results show that the FAC distribution in the plasma sheet boundary layers in the magnetotail has dusk‐dawn asymmetry, earthward‐tailward (polarity) asymmetry, and north‐south asymmetry. The occurrence and polarities of FACs in the Northern Hemisphere are different from those in the Southern Hemisphere. The average density and the standard deviation of the FACs that are most likely to be connected to the Earth are 4.90 nA m−2 and 2.55 nA m−2 in the Northern Hemisphere and 4.21 nA m−2 and 1.80 nA m−2 in the Southern Hemisphere, respectively. For investigating the mechanism of the north‐south asymmetry, we mapped the FACs along the field line into the polar region. The footprints of the FACs also show a difference between the Southern and Northern hemispheres (as a function of mapped latitude). These characteristics suggest a north‐south asymmetry of the FACs in the magnetosphere. Further investigation is needed to identify the causes of this asymmetry, although the configuration of the magnetosphere, the polar cap boundary, the conductivity in the ionosphere, or the various solar wind‐magnetosphere interaction processes all may be contributors. That the FAC densities are different between the hemispheres suggests that an important source of these currents must be a voltage generator.
Influence of climate model biases and daily‐scale temperature and precipitation events on hydrological impacts assessment: A case study of the United States
Authors: Ashfaq Moetasim , Bowling Laura C. , Cherkauer Keith , Pal Jeremy S. , Diffenbaugh Noah S.
Published: July 2010

The Intergovernmental Panel on Climate Change's Fourth Assessment Report concludes that climate change is now unequivocal, and associated increases in evaporation and atmospheric water content could intensify the hydrological cycle. However, the biases and coarse spatial resolution of global climate models limit their usefulness in hydrological impact assessment. In order to reduce these limitations, we use a high‐resolution regional climate model (RegCM3) to drive a hydrological model (variable infiltration capacity) for the full contiguous United States. The simulations cover 1961–1990 in the historic period and 2071–2100 in the future (A2) period. A quantile‐based bias correction technique is applied to the times series of RegCM3‐simulated precipitation and temperature. Our results show that biases in the RegCM3 fields not only affect the magnitude of hydrometeorological variables in the baseline hydrological simulation, but they also affect the response of hydrological variables to projected future anthropogenic increases in greenhouse forcing. Further, we find that changes in the intensity and occurrence of severe wet and hot events are critical in determining the sign of hydrologic change. These results have important implications for the assessment of potential future hydrologic changes, as well as for developing approaches for quantitative impacts assessment.
Stability of bubbles in a linear elastic medium: Implications for bubble growth in marine sediments
Authors: Algar C. K. , Boudreau B. P.
Published: July 2010

Methane bubbles in muddy fine‐grained sediments grow initially through a process of elastic expansion, punctuated by discrete fracture events (LEFM‐growth). The ability of the surrounding sediments to support a stress and actively resist expansion can, under conditions of low gas production or high sediment toughness, result in the cessation of growth and the presence of stable bubbles. Thus, it is possible for a bubble to stop growing despite the presence of a source in the sediments that continues to produce gas. This contrasts with growth of bubbles in a fluid medium, which cannot support a stress and so will continue to grow as long as a surrounding source provides gas. This “no‐growth” condition is the result of the coupling between gas supply (methane production or supersaturation) and the sediment mechanics. Here we quantify this condition and present a criterion for the switch between no‐growth and the LEFM growth regimes. We apply this theory to the sediments of Eckernförde Bay, in the Kiel Bight, Germany, and despite the absence of measurements for the key sediment mechanical properties, we can provide a qualitative explanation for the sizes and shapes of the observed bubble population with depth in the sediment. We also show how the release of hydrostatic pressure can stimulate growth, by pushing otherwise stable bubbles into the LEFM growth regime. This could provide a mechanism for the release of bubbles during periods of low water, such as during low tide or wave events.
Simulating the thermal behavior of northern peatlands with a 3‐D microtopography
Authors: Kettridge Nicholas , Baird Andrew J.
Published: July 2010

Globally, peatlands represent important stores of carbon which may have an important influence on future climatic conditions. Understanding how peatlands will influence, and also respond to, future climates will require an understanding of their thermal behavior. Peatland surfaces are often characterized by a 3‐D microtopography. Therefore, we might expect strong horizontal thermal gradients and exchanges between neighboring microforms with contrasting hydrological regimes and vegetation composition. However, previous peatland temperature models have assumed that horizontal temperature gradients are insignificant and that temperatures can be simulated adequately by applying 1‐D vertical models. We outline the development, parameterization, and evaluation of a 3‐D model that simulates peat temperatures in two microforms, a Sphagnum fuscum hummock surrounded by a Sphagnum magellanicum lawn, to identify the importance of such horizontal heat fluxes. The 3‐D Heat‐in‐Peat (HIP) model provides a reasonable representation of temperatures in the microforms with a root‐mean‐squared error between modeled and measured peat temperatures ranging from 2.33° to 0.20°C. The 3‐D HIP model highlights the importance of a 3‐D microtopography on the surface energy balance and peat temperatures. Comparison of the 3‐D HIP model with 1‐D simulations of peat temperatures shows that horizontal temperature gradients significantly influence peat temperatures within the hummock, with simulated temperatures at a depth of 0.375 m beneath the hummock being underestimated by up to 1.2°C in 1‐D simulations. In contrast, temperatures within the Sphagnum magellanicum lawn were adequately simulated by ignoring horizontal heat fluxes.
Tumor Necrosis Factor‐α (TNF‐α), Interferon‐γ, and Interleukin‐6 but Not TNF‐β Induce Differentiation of Neuroblastoma Cells: The Role of Nitric Oxide
Authors: Muñoz‐Fernández M. Angeles , Cano Eva , O'Donnell Catherine A. , Doyle Jackie , Liew F. Y. , Fresno Manuel
Published: July 2010

Abstract:Tumor necrosis factor‐a (TNF‐α), interferon‐γ (IFN‐7), and interleukin‐6 (IL‐6), but not TNF‐β, can induce the in vitro differentiation of the neuroblastoma cell line N103 in a dose‐dependent manner. Differentiation of N103 was accompanied by the arrest of cell growth and neurite formation. The induction of neuroblastoma cell differentiation by TNF‐α and IFN‐γ can be specifically inhibited by a nitric oxide (NO) synthase inhibitor,l‐NG‐monomethylarginine. In contrast, the differentiation of N103 cells by IL‐6 was not affected byl‐NG‐monomethylarginine. These results indicate that TNF‐α and IFN‐γ, but not IL‐6, induce the differentiation of neuroblastoma cells via NO. This is confirmed by the finding that the culture super‐ natants of N103 cells induced by TNF‐α and IFN‐γ, but not that by IL‐6, contained high levels of NO2−, the production of which was inhibited byl‐NG‐monomethylarginine. Furthermore, the differentiation of N103 cells can be induced directly in a dose‐dependent manner by the addition of nitroprusside, a generator of NO, into the culture medium. These data therefore indicate that NO may be an important mediator in the induction of neuronal cell differentiation by certain cytokines such as TNF‐α and IFN‐γ and that neuronal cells, in addition to the macrophagelike brain cells, can be induced by immunological stimuli to produce large quantities of NO.
Endothelin‐ and Sarafotoxin‐Induced Phosphoinositide Hydrolysis in Cultured Canine Tracheal Smooth Muscle Cells
Authors: Yang Chuen Mao , Yo Ying‐Ling , Ong Richard , Hsieh Jen‐Tsung
Published: July 2010

Abstract:The endothelins (ETs) and sarafotoxin are two structurally related classes of potently contractile peptides. To understand the mechanism of action of ETs, we have examined the effect of ETs and sarafotoxin on phosphoinositide (PI) hydrolysis in cultured canine tracheal smooth muscle cells (TSMCs). ET‐1, ET‐2, ET‐3, and sarafotoxin caused dose‐dependent accumulation of inositol phosphates (IPs) and tracheal smooth muscle contraction. BQ‐123, an ETAreceptor antagonist, had a high affinity to block the ET‐1‐induced IP accumulation and tracheal smooth muscle contraction withpKBvalues of 7.3 and 7.4, respectively. Pretreatment of TSMCs with cholera toxin impaired the ability of ET‐1 and ET‐2 to stimulate IP formation, whereas there was no effect by treatment with pertussis toxin. Stimulation of PI turnover by these peptides required the presence of extracellular Ca2+and was blocked by treatment with EGTA. The addition of Ca2+(3–620 nM) to digitonin‐permeabilized TSMCs directly stimulated IP accumulation. A further Ca2+‐dependent increase in IP formation was obtained by inclusion of either GTPrS or ET‐1. The combined presence of GTPrS and ET‐1 elicited an additive effect on IP formation. Short‐term exposure to phorbol 12‐myristate 13‐acetate (PMA, 1 μM) abolished the stimulation of PI hydrolysis induced by these peptides. The inhibitory effect of PMA on ET‐induced response was reversed by staurosporine, a protein kinase C (PKC) inhibitor, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. Prolonged incubation of TSMCs with PMA resulted in a recovery of receptor responsiveness that may be due to down regulation of PKC. Inactive phorbol ester, 4α‐phorbol 12, 13‐didecanoate at 1 μM, did not inhibit this response. The site of this response was further investigated by examining the effect of PMA on AIF4−‐induced IP accumulation in canine TSMCs. AIF4−‐induced IP accumulation was inhibited by PMA treatment, suggesting that G protein(s) can be directly activated by AIF4−, which was uncoupled to phospholipase C by PMA treatment. These data conclude that ET‐stimulated PI hydrolysis and tracheal smooth muscle contraction are mediated by the activation of ETAreceptors coupling to a G protein and dependent on the external Ca2+. The transduction mechanism of ETs is sensitive to feedback regulation by PKC.
Identification of Endothelin Receptor Subtype (ETB) in Human Cerebral Cortex Using Subtype‐Selective Ligands
Authors: Fernández‐Durango Raquel , de Juan José A. , Zimman Horatio , Moya Francisco J. , Coba Mario Garcia de la , Fernández‐Cruz Arturo
Published: July 2010

Abstract: Specific endothelin (ET) binding sites were characterized in membranes prepared from human cerebral cortices using binding assay and cross‐linking analysis. The presence of immunoreactive (IR) ET‐1 was studied by radioimmunoassay. Saturation binding experiments revealed that theKDandBmaxfor125I‐ET‐1 and125l‐ET‐3 to membranes from gray matter were 25 ± 6pMand 115 ± 15 fmol/mg of protein and 24 ± 5 pMand 108 ± 13 fmol/mg of protein, respectively. Similar results were obtained for white matter. In the presence of 10 nMsarafotoxin‐6c, which is selective for ETBreceptors,125I‐ET‐1 and125l‐ET‐3 binding was totally abolished. However, in the presence of 1 μMBQ123, which is selective for ETAreceptors, both bindings were not affected. These results suggest that the human cerebral cortex contains only ETBreceptors. Cross‐linking of125I‐ET‐1 and125l‐ET‐3 to membranes with disuccinimidyl suberate resulted in the labeling of two bands of 48 and 31 kDa. Concentrations of IR‐ET‐1 in the gray and white matter were 7.0 ± 3.2 and 2.5 ± 1.7 fmol/g wet weight, respectively. The demonstration of high‐affinity ETBreceptors and the presence of IRET‐1 suggest that the peptide may act as a neurotransmitter or neuromodulator in the human cerebral cortex.
Subcellular Localization and Characterization of Neuronal Nitric Oxide Synthase
Authors: Hecker Markus , Mülsch Alexander , Busse Rudi
Published: July 2010

Abstract:In contrast to the predominantly participate, Ca2+/calmodulin‐dependent nitric oxide (NO) synthase in endothelial cells, the corresponding neuronal isoenzyme is considered to be mainly soluble, presumably owing to the lack of a posttranslational myristoylation. However, preliminary findings from this and other laboratories suggest that a substantial portion of the neuronal NO synthase activity may in fact be membrane bound. We have therefore investigated the distribution of this enzyme among subcellular fractions of the rat and rabbit cerebellum in more detail. Up to 60% of the total NO synthase activity was found in the particulate fraction and, according to density gradient ultracentrifugation, associated mainly with the endoplasmic reticulum fraction. There was no apparent difference between the soluble and particulate enzymes with respect to their specific activity, Ca2+and pH dependency, inhibitor sensitivity, or immunoreactivity, suggesting that both rat and rabbit cerebella contain a single Ca2+/calmodulin‐dependent NO synthase. The inhibition by the cytochrome P450 inhibitor SKF‐525A of the NO synthase activity in these subcellular fractions (IC50= 90 μM) and the fact that mammalian cytochrome P450 enzymes are endoplasmic reticulum‐bound proteins support the notion that the cerebellar NO synthase is a cytochrome P450‐type hemoprotein. Moreover, the aforementioned findings suggest that posttranslational myristoylation may not be the only factor determining the intracellular localization of NO synthase.
Temporal and Depolarization‐Induced Changes in the Absolute Amounts of mRNAs Encoding Metabotropic Glutamate Receptors in Cerebellar Granule Neurons In Vitro
Authors: Santi Maria Rita , Ikonomovic Snezana , Wroblewski Jarda T. , Grayson Dennis R.
Published: July 2010

Abstract: Cerebellar granule neurons in primary culture express metabotropic glutamate receptors (mGluRs) coupled to the stimulation of phosphoinositide hydrolysis and to the inhibition of cyclic AMP (cAMP) formation. To evaluate which mGluR mRNAs are expressed in granule neurons under different depolarizing conditions, we measured the absolute amounts of selected receptor mRNAs in neurons cultured for 3–13 days in the presence of either 10 or 25 mM KCl. mGluR‐specific primer pairs and internal standards, corresponding to unique regions of mGluR1a, mGluR2, mGluR3, mGluR4, and mGluR5, were constructed and used in a competitive PCR‐derived assay to quantify the corresponding mRNA levels. For phosphoinositide‐coupled receptors, the absolute content of mGluR1a mRNA was three to 10 times higher than the content of mGluR5 mRNA. The expression of mGluR5 mRNA increased up to 9 days in vitro and was much higher in 10 mM than in 25 mM KCl. For the cAMP‐coupled receptors, there was a large amount of mGluR4 mRNA and a much smaller content of the mGluR3 and mGluR2 mRNAs. Maintaining the granule neurons in vitro in 10 mM KCl increased the absolute amount of mRNAs encoding mGluR2 and mGluR4 at 9 and 13 days in vitro. In contrast, the content of the mGluR3 mRNA was consistently higher in neurons cultured in 25 mM KCl. These data are consistent with the possibility that in primary cultures of cerebellar neurons, phosphoinositide responses may be predominantly mediated by mGluR1a, rather than mGluR5, and that cAMP inhibition involves preferentially mGluR4 and mGluR3.
The Striatal Transporter for Dopamine in the Rat May Be Kinetically Up‐Regulated Following 3 Weeks of Withdrawal from Cocaine Self‐Administration
Authors: Meiergerd Susan M. , Hooks Stacy M. , Schenk James O.
Published: July 2010

Abstract: Rotating disk electrode voltammetry was used to measure the inwardly directed Vmax and Km of dopamine with its transporter in striatal suspensions prepared from nonhandled control rats, rats that had been trained to self‐administer cocaine for 20 days (at 26 mg/day per rat) via a jugular catheter and subsequently withdrawn for 3 weeks, and rats that had received saline (155 mM NaCl) via a jugular catheter on the same schedule as the rats that had received cocaine. Because a limited number of animals was available from the self‐administration procedure, the velocity of dopamine transport as a function of [dopamine] was measured by incremental addition of dopamine to a given striatal preparation. In nonhandled controls the values of Vmax, Km, and turnover, observed in this experimental paradigm, were increased relative to results obtained in studies of the velocity‐[dopamine] relationship where dopamine was added to suspensions, one concentration per suspension. The kinetics of the association of dopamine with the transporter were unchanged. The Vmax to Km ratios obtained in the two experiments were statistically indistinguishable, suggesting that the two types of experiments probe the same transporter. Also, the increased velocity observed in the experiment involving sequential additions to the same preparation is evidence of trans acceleration, suggesting that the movement of dopamine across the membrane is carrier mediated as opposed to being mediated via channels or pores and that the rate‐limiting step in inwardly directed transport is the reorientation of the unloaded transporter from the inwardly to the outwardly facing forms. Saline‐treated rats in the self‐administration paradigm exhibited kinetic parameters of transport indistinguishable from those observed in nonhandled controls. In contrast, Vmax and Km of the transporter were increased in suspensions prepared from rats that self‐administered cocaine and were withdrawn for 3 weeks, relative to saline‐treated and nonhandled animals. Combined, these results suggest that the striatal uptake of dopamine is mediated by a transporter and that it is kinetically up‐regulated following withdrawal from repeated cocaine administered in a self‐administration paradigm.
Neonatal 6‐Hydroxydopamine and Adult SKF 38393 Treatments Alter Dopamine D1 Receptor mRNA Levels: Absence of Other Neurochemical Associations with the Enhanced Behavioral Responses of Lesioned Rats
Authors: Gong Li , Kostrzewa Richard M. , Li Chuanfu
Published: July 2010

Abstract: To study potential biochemical correlates of dopamine (DA) and serotonin receptor supersensitivity, rats were lesioned at 3 days after birth with 6‐hydroxydopamine (6‐OHDA; 67 µg in each lateral ventricle; desipramine pretreatment, 20 mg/kg i.p., 1 h) and then sensitized with the DA D1 agonist, SKF 38393 HCl (3.0 mg/kg i.p. per day) either ontogenetically (daily, for 28 consecutive days from birth) and/or in adulthood (four weekly injections, 6–9 weeks from birth). Controls received vehicle in place of 6‐OHDA or SKF 38393. Enhanced locomotor responses were observed after SKF 38393 at 6 weeks, only in rats that received SKF 38393 + 6‐OHDA in ontogeny. Locomotor responses were further enhanced in this group after the last of four weekly SKF 38393 injections at the 9th week. These weekly SKF 38393 treatments also produced enhanced responses in 6‐OHDA rats that did not receive SKF 38393 in ontogeny. When striata were studied at 11 weeks, the percentages of high and low affinity DA D1 binding sites were not altered. Basal as well as DA‐, NaF‐, and forskolin‐stimulated adenylyl cyclase activities also were not changed. Dot blot analysis showed that there was a reduction of mRNA levels for DA D1, but not serotonin1C, receptors in the 6‐OHDA groups. However, SKF 38393 at 6–9 weeks eliminated this alteration. Based on these findings it can be proposed that supersensitization may be a consequence of altered neuronal cross talk rather than an imbalance of receptor elements per se.
Regulation of Rat Brain Synaptosomal [3H]Hemicholinium‐3 Binding and [3H]Choline Transport Sites Following Exposure to Choline Mustard Aziridinium Ion
Authors: Ferguson S. S. G. , Rylett R. J. , Collier B.
Published: July 2010

Abstract: Choline uptake by cholinergic nerve terminals is increased by depolarization; the literature suggests that this results from either the appearance of occult transporters or the increased activity of existing ones. The present experiments attempt to clarify the mechanism by which choline transport is regulated by testing if the preexposure of synaptosomes to choline mustard aziridinium ion prevents the stimulation‐induced appearance of hemicholinium‐3 binding sites and/or choline transport activity. Choline mustard inhibited irreversibly most of the “ground‐state” (basal) high‐affinity choline transport but only 50% of “ground‐state” hemicholinium‐3 binding sites. Exposure of both striatal and hippocampal synaptosomes to the mustard, before stimulation, inhibited K+‐stimulated increases in choline transport and of [3H]hemicholinium‐3 binding. We conclude that the mechanism by which choline transport is regulated involves the increased activity of a pool of transport sites that are occluded to hemicholinium‐3 but are available to choline mustard aziridinium ion, and presumably to choline, before stimulation. However, the concentration of mustard needed to inhibit the stimulation‐induced increase of [3H]hemicholinium‐3 binding and choline transport was lower for striatal synaptosomes than for hippocampal synaptosomes. In the absence of extracellular Ca2+ or presence of high Mg2+ levels, the choline mustard did not prevent the appearance of extra striatal hemicholinium‐3 binding sites. Also, high Mg2+ levels removed the ability of the mustard to inhibit K+‐stimulated increases of either [3H]hemicholinium‐3 binding or choline transport by hippocampal synaptosomes. In contrast, the preexposure of hippocampal synaptosomes to the mustard in the presence of a calcium ionophore (A23187) reduced the concentration of inhibitor needed to prevent the activation of [3H]hemicholinium‐3 binding and choline uptake. Thus, we conclude that the ability of the choline mustard to alkylate the pool of choline transporters that are activated by stimulation appears dependent on the entry of extracellular Ca2+.
Metabotropic Glutamate Receptor in C6BU‐1 Glioma Cell Has NMDA Receptor‐Ion Channel Complex‐Like Properties and Interacts with Serotonin2 Receptor‐Stimulated Signal Transduction
Authors: Shinno Hideto , Mikuni Masahiko , Saitoh Kazuko , Tomita Urara , Yamawaki Shigeto , Takahashi Kiyohisa
Published: July 2010

Abstract: We found in cultured glioma (C6BU‐1) cells that excitatory amino acids (EAAs) such as glutamate, N‐methyl‐d‐aspartate (NMDA), aspartate, and metabotropic glutamate receptor agonist trans‐(±)‐1‐amino‐1,3‐cyclopentanedicarboxylate caused an increase in the inositol 1,4,5‐trisphosphate formation and the intracellular Ca2+ concentration ([Ca2+]i) in the absence of extracellular Mg2+ and Ca2+. Pertussis toxin treatment abolished this glutamate‐induced [Ca2+]i increase. Various antagonists against NMDA receptor‐ion channel complex, such as Mg2+, d‐2‐amino‐5‐phosphonovalerate (d‐APV), HA‐966, and MK‐801, also inhibited the increase in [Ca2+]i induced by glutamate. These results indicate that these metabotropic EAA receptors coupled to pertussis toxin‐susceptible GTP‐binding protein and phospholipase C system in C6BU‐1 glioma cells have the pharmacological properties of NMDA receptor‐ion channel complexes. We also found that in the presence of Mg2+ these metabotropic receptors resemble the NMDA receptor‐ion channel complex interacted with 5‐hydroxytryptamine2 (5‐HT2) receptor signaling. EAAs inhibited 5‐HT2 receptor‐mediated intracellular Ca2+ mobilization and inositol 1,4,5‐trisphosphate formation in a concentration‐dependent manner. The inhibitory effect of glutamate was reversed by various NMDA receptor antagonists (d‐APV, MK‐801, phencyclidine, and HA‐966), but l‐APV failed to block the inhibitory effect of glutamate. The same result was observed in the absence of extracellular Ca2+. In addition, this inhibitory effect on 5‐HT2 receptor‐mediated signal transduction was abolished by treatment of C6BU‐1 cells with pertussis toxin, whereas 5‐HT2 receptor‐mediated [Ca2+]i increase was not abolished by pertussis toxin treatment. We can, therefore, conclude that the inhibitory effect of glutamate is not a result of the influx of Ca2+ through the ion channel and that it operates via metabotropic glutamate receptors, having NMDA receptor‐ion channel complex‐like properties and being coupled with pertussis toxin‐sensitive GTP‐binding protein and phospholipase C.
Thyroid Hormone Replacement Restores Circulating Enkephalin Concentrations in Hypophysectomized Fetal Sheep
Authors: Simonetta Giuseppe , Young I. Ross , McMillen I. Caroline
Published: July 2010

Abstract: We have investigated the effects of fetal hypophysectomy (HX) with or without thyroxine (T4) replacement on the plasma concentrations of free methionine‐enkephalin (free Met‐Enk), noradrenaline, and adrenaline in late gestation sheep fetus. Plasma adrenaline concentrations were significantly higher in intact fetal sheep (1.05 ± 0.12 pmol/L) between 125 and 140 days of gestation when compared with the HX + saline (0.64 ± 0.10 pmol/L) and HX + T4 (0.61 ± 0.08 pmol/L) groups. During the first 15 days of the T4 or saline infusion, the plasma concentrations of free Met‐Enk were significantly higher in the HX + T4 group (392 ± 40 pmol/L) than in the HX + saline group (299 ± 43 pmol/L). At this stage of gestation, however, circulating concentrations of free Met‐Enk were significantly higher in intact fetal sheep (556 ± 51 pmol/L) than in either of the HX groups. Between 125 and 140 days of gestation, plasma free Met‐Enk concentrations were similar and significantly higher in the intact and HX + T4 groups than those measured in the HX + saline fetal sheep. We conclude that the decrease in circulating free Met‐Enk concentrations after removal of the fetal pituitary is primarily a consequence of functional athyroidism.
Photoaffinity Labeling with Progesterone‐11α‐Hemisuccinate‐(2‐[125I]Iodohistamine) Identifies Four Protein Bands in Mouse Brain Membranes
Authors: Büküsoglu Cüneyt , Krieger Neil R.
Published: July 2010

Abstract: The radiolabeled progesterone (PG) analogue progesterone‐11α‐hemisuccinate‐(2‐[125I]iodohistamine) was used to label PG binding proteins in brain membranes from mouse cerebellum. Photoaffinity labeling and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis identified specific PG binding protein bands 1–4 of 64−29 kDa. Bands 1 and 4 were well resolved on the gel and easily quantified. Preincubation with PG inhibited photolabeling in a dose‐dependent manner. The labeling was specific with respect to steroid structure. For band 1, the extent of inhibition of labeling by PG and 3α,5α‐pregnanolone (3α) was pronounced. Other steroids such as testosterone (Tes), estradiol (Est), and corticosterone (Cor) were less effective, whereas pregnenolone sulfate (PS) and cholesterol (Cho) were ineffective. With respect to band 4, Est was the most effective; PG, 3α, and Tes were intermediate; and PS, Cho, and Cor were ineffective. The results describe specific membrane proteins that bind PG (band 1) and Est (band 4).
Diacylglycerol Kinase Is Stimulated by Arachidonic Acid in Neural Membranes
Authors: Raja Rao K. V. , Vaidyanathan V. V. , Sastry P. S.
Published: July 2010

Abstract: The effect of arachidonic acid (AA) on the activity of diacylglycerol (DG) kinase in neural membranes was investigated. When rat brain cortical membranes were incubated with 0.5 mM dipalmitin and [γ‐32P]ATP, formation of phosphatidic acid (PA) was observed. It was linear up to 5 min, and the initial rate was ∼1.0 nmol/min/mg of protein. The DG kinase activity was stimulated twofold by 0.25 mM AA. The stimulation was apparent at the earliest time point measured (1 min) and with the lowest concentration of AA tested (62.5 µM). The stimulation was proportional to the concentration of AA up to 250 µM. AA was the most potent stimulator of DG kinase, and linolenic acid showed ∼40% stimulation. Oleic acid showed no effect, whereas linoleic and the saturated fatty acids tested were inhibitory. AA stimulation of DG kinase was observed only with membranes of cerebrum, cerebellum, and myelin and not with brain cytosol or liver membranes. AA also stimulated the formation of PA in the absence of added dipalmitin (endogenous activity) with membranes prepared from whole brain. DG kinase of neural membranes was extracted with 2 M NaCl, which on dialysis yielded a precipitate. Both the precipitate and the supernatant showed DG kinase activity, but only the enzyme in the precipitate was stimulated by AA at concentrations as low as 25 µM. It is suggested that AA, through its effect on DG kinase, regulates the level of DG in neural membranes, which in turn regulates protein kinase C activity.
Heterogeneous Expression of Transketolase in Rat Brain
Authors: Calingasan Noel Y. , Sheu Kwan‐Fu Rex , Baker Harriet , Jung Eun‐Hee , Paoletti Francesco , Gibson Gary E.
Published: July 2010

Abstract: Transketolase (TK; EC 2.2.1.1) is a key pentose phosphate shunt enzyme that plays an important role in the production of reducing equivalents and pentose sugars. TK activity declines in the brains of patients with Alzheimer's disease or Wernicke‐Korsakoff syndrome, as well as in thiamine‐deficient rats. Understanding the role of TK in the pathophysiology of these neurodegenerative conditions requires knowledge of its regional, cellular, and subcellular distribution within the brain. The current study employed in situ hybridization and immunocytochemistry to examine the distribution of TK mRNA and its encoded protein in adult rat brain. TK mRNA and protein were widely distributed throughout the brain. However, they were enriched in selective perikarya in the piriform cortex, nucleus of the diagonal band, red nucleus, dorsal raphe, pontine nucleus, locus coeruleus, trapezoid, inferior olive, and several cranial nerve nuclei. Lower expression of TK mRNA and protein occurred in layer V of cortex, olfactory tubercle, ventral pallidum, medial septal nucleus, hippocampus, thalamic and hypothalamic nuclei, mammillary body, central gray, and the substantia nigra. TK immunoreactivity also occurred in the nuclei of ubiquitously distributed glial cells, as well as ependymal cells. The heterogeneous distribution of TK may reflect a variety of metabolic activities among different brain regions but does not provide a simple molecular explanation for selective cell death in either thiamine deficiency or other conditions where TK is reduced.
N‐Linked Glycosylation of the α‐Amino‐3‐Hydroxy‐5‐Methylisoxazole‐4‐Propionate(AMPA)‐Selective Glutamate Receptor Channel α2 Subunit Is Essential for the Acquisition of Ligand‐Binding Activity
Authors: Kawamoto Susumu , Hattori Satoshi , Sakimura Kenji , Mishina Masayoshi , Okuda Kenji
Published: July 2010

Abstract: The N‐linked glycosylation of the α2 subunit of the mouse α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate(AMPA)‐selective glutamate receptor (GluR) channel was characterized. The receptor subunit protein has five putative N‐glycosylation sites. The recombinant receptor proteins were identified by [35S]methionine/[35S]cysteine metabolic labeling, western blot analysis, immunocytochemical detection, and [3H]AMPA binding experiments when expressed in insect Spodoptera frugiperda cells using a baculovirus system. The effect of tunicamycin on the metabolic labeling and immunoblots suggested that the two products, a major protein species of ∼102 kDa and a minor species of ∼98 kDa, correspond to glycosylated and unglycosylated forms, respectively, which was also supported by the enzymic deglycosylation experiments. Immunofluorescence staining of tunicamycin‐treated cells expressing only the unglycosylated form differed little from that of tunicamycin‐nontreated cells expressing both glycosylated and unglycosylated forms. The lack of AMPA‐binding activity of the unglycosylated form expressed in the presence of tunicamycin suggested that N‐glycosylation is required, directly or indirectly, for functional expression in insect cells for ligand binding. These results demonstrate that occupancy of at least one N‐glycosylation site is required for the formation and maintenance of the GluRα2 subunit protein in an active conformation for ligand binding. Possible roles of N‐glycosylation of GluRα2 subunit protein are discussed.
Accumulation of Enkephalin, Proenkephalin mRNA, and Neuropeptide Y in Immunologically Denervated Rat Adrenal Glands: Evidence for Divergent Peptide Regulation
Authors: Brimijoin S. , Dagerlind Å. , Rao R. , McKinzie S. , Hammond P.
Published: July 2010

Abstract: To investigate transsynaptic effects on peptides of adrenal chromaffin cells in the rat, presynaptic sympathetic terminals were destroyed by intravenous injection of monoclonal antibodies to acetylcholinesterase. At several times thereafter, neuropeptide Y (NPY)‐like immunoreactivity (NPY‐IR) and methionine‐enkephalin‐like immunoreactivity (Met‐Enk‐IR) were measured by radioimmunoassay. Within 2 days of antibody injection, adrenal Met‐Enk‐IR increased five‐ to 10‐fold and NPY‐IR increased 50%. These effects were accompanied by large increases in proenkephalin A mRNA assayed by polymerase chain reaction. The peptide responses could reflect either an acute activation, as presynaptic terminals degenerated, or a chronic synaptic inactivation after terminal degeneration. To test the possibilities, muscarinic and nicotinic receptors were inhibited by repeated injection of atropine (1 mg/kg) and chlorisondamine (5 mg/kg). Measurements of urinary free catecholamine excretion showed that this treatment prevented the paroxysmal release of norepinephrine and reduced the release of epinephrine that normally followed injection of acetylcholinesterase antibodies. When the drugs were given alone for 2 or 4 days, adrenal Met‐Enk‐IR increased modestly and NPY‐IR remained steady or declined. When given together with acetylcholinesterase antibodies, the cholinergic antagonists blocked the increase of NPY‐IR but not Met‐Enk‐IR. Adding naloxone (1 mg/kg) to the treatment regimen enhanced the blockade of epinephrine excretion and largely prevented the antibody‐induced increase in Met‐Enk‐IR. These findings indicate that adrenal NPY and enkephalin are not regulated identically. Adrenal NPY behaves as though controlled by transsynaptic cholinergic input. On the other hand, adrenal enkephalin may be regulated by additional or different mechanisms, possibly involving peptidergic transmission or synaptic inactivation.
DMAP‐85: A τ‐Like Protein from Drosophila melanogaster Larvae
Authors: Cambiazo Verónica , González Mauricio , Maccioni Ricardo B.
Published: July 2010

Abstract: Microtubule‐associated proteins (MAPs) play major regulatory roles in the organization and integrity of the cytoskeletal network. Our main interest in this study was the identification and the analysis of structural and functional aspects of Drosophila melanogaster MAPs. A novel MAP with a relative molecular mass of 85 kDa from Drosophila larvae was found associated with taxol‐polymerized microtubules. In addition, this protein bound to mammalian tubulin in an overlay assay and coassembled with purified bovine brain tubulin in microtubule sedimentation experiments. The estimated stoichiometry of 85‐kDa protein versus tubulin in the polymers was 1:5.3 ± 0.2 mol/mol. It was shown that the 85‐kDa protein bound specifically to an affinity column of Sepharose‐βII‐(422–434) tubulin peptide, which contains the sequence of the MAP binding domain on βII‐tubulin. Affinity‐purified 85‐kDa protein enhanced microtubule assembly in a concentration‐dependent manner. This effect was significantly decreased by the presence of the βII‐(422–434) peptide in the assembly assays, thus confirming the specificity of the 85‐kDa protein interaction with the C‐terminal domain on tubulin. Furthermore, this protein also exhibited a strong affinity for calmodulin, based on affinity chromatographic assays. Monoclonal and polyclonal anti‐τ antibodies, including sequence‐specific probes that recognize repeated microtubule‐binding motifs on τ, MAP‐2, and MAP‐4 and specific N‐terminal sequences of τ, cross‐reacted with the 85‐kDa protein from Drosophila larvae. These results suggest that τ and Drosophila 85‐kDa protein share common functional and structural epitopes. We have named this protein as DMAP‐85 for Drosophila MAP. The finding on a Drosophila protein with functional homology and structural similarities to mammalian τ opens new perspectives to understand the cellular roles of MAPs.
Electrochemical cell for neutron reflectometry studies of the structure of ionic liquids at electrified interface
Authors: Lauw Y. , Rodopoulos T. , Gross M. , Nelson A. , Gardner R. , Horne M. D.
Published: July 2010

We describe the design and use of a closed three-electrode electrochemical cell for neutron reflectometry studies of the structure of the electrical double-layer in ionic liquids. A transparent glass counter electrode was incorporated to allow easy monitoring of any gas bubbles trapped in the cell. A 100 mm diameter silicon wafer polished to 0.1 nm rms roughness coated with gold over a chromium adhesion layer was used as the working electrode. The utility of the cell was demonstrated during neutron reflectometry measurements of the ultrahigh purity ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyr][NTf2]) at two different applied potentials.
Growth of vertically-aligned carbon nanotube forests on conductive cobalt disilicide support
Authors: Zhang C. , Yan F. , Allen C. S. , Bayer B. C. , Hofmann S. , Hickey B. J. , Cott D. , Zhong G. , Robertson J.
Published: July 2010

We report the thermal chemical vapor deposition of vertically-aligned multiwalled carbon nanotube forests directly onto electrically conductive cobalt disilicide (CoSi2) support using Fe as catalyst. We find that CoSi2 support layer is able to prevent the agglomeration of the catalyst and favor vertically-aligned growth better than a SiO2 support and comparable to an Al2O3 support. This is an unusual behavior for a conductive support. This is because CoSi2 has a lower surface energy than most metals or metallic compounds. This has great benefits in the application of CoSi2 as support for CNTs as horizontal and vertical interconnects.
Direct hole injection in to 4,4′-N,N′-dicarbazole-biphenyl: A simple pathway to achieve efficient organic light emitting diodes
Authors: Wang Z. B. , Helander M. G. , Qiu J. , Liu Z. W. , Greiner M. T. , Lu Z. H.
Published: July 2010

The conventional carrier-blocking design of the exciton formation zone used in nearly all organic light emitting diodes is shown to be problematic, due to exciton quenching from accumulated radical cations. To reduce exciton quenching, a single layer of 4,4′-N,N′-dicarbazole-biphenyl (CBP) is used as hole transport layer, resulting in a dramatically improved device efficiency even at high luminance (e.g., 20.5 cd/A at 100 000 cd/m2 for fluorescent green). Various high work function transition metal oxides (WO3, V2O5, and MoO3) coated on indium tin oxide anodes have been shown to enable direct hole injection into the deep highest occupied molecular orbital of CBP (6.1 eV).