bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glutamate regulates neurite outgrowth of cultured descending brain neurons from larval lamprey
Authors: Ryan Sarah K. , Shotts Lindsay R. , Hong Soo‐Kyung , Nehra Deepika , Groat Carl R. , Armstrong Jon R. , McClellan Andrew D. 
Published: January 2007

AbstractIn larval lamprey, descending brain neurons, which regenerate their axons following spinal cord injury, were isolated and examined in cell culture to identify some of the factors that regulate neurite outgrowth. Focal application of 5 mMor 25 mML‐glutamate to single growth cones inhibited outgrowth of the treated neurite, but other neurites from the same neuron were not inhibited, an effect that has not been well studied for neurons in other systems. Glutamate‐induced inhibition of neurite outgrowth was abolished by 10 mMkynurenic acid. Application of high potassium media to growth cones inhibited neurite outgrowth, an effect that was blocked by 2 mMcobalt or 100 μMcadmium, suggesting that calcium influx via voltage‐gated channels contributes to glutamate‐induced regulation of neurite outgrowth. Application of glutamate to growth cones in the presence of 2 μMω‐conotoxin MVIIC (CTX) still inhibited neurite outgrowth, while CTX blocked high potassium‐induced inhibition of neurite outgrowth. Thus, CTX blocked virtually all of the calcium influx resulting from depolarization. To our knowledge, this is the first direct demonstration that calcium influx via ligand‐gated ion channels can contribute to regulation of neurite outgrowth. Finally, focal application of glutamate to the cell bodies of descending brain neurons inhibited outgrowth of multiple neurites from the same neuron, and this is the first demonstration that multiple neurites can be regulated in this fashion. Signaling mechanisms involving intracellular calcium, similar to those shown here, may be important for regulating axonal regeneration following spinal cord injury in the lamprey. © 2006 Wiley Periodicals, Inc. Develop Neurobiol 67: 173–188, 2007.
Electrical stimulation promotes peripheral axon regeneration by enhanced neuronal neurotrophin signaling
Authors: English Arthur W. , Schwartz Gail , Meador William , Sabatier Manning J. , Mulligan Amanda 
Published: January 2007

AbstractElectrical stimulation of cut peripheral nerves at the time of their surgical repair results in an enhancement of axon regeneration. Regeneration of axons through nerve allografts was used to evaluate whether this effect is due to an augmentation of cell autonomous neurotrophin signaling in the axons or signaling from neurotrophins produced in the surrounding environment. In the thy‐1‐YFP‐H mouse, a single 1 h application of electrical stimulation at the time of surgical repair of the cut common fibular nerve results in a significant increase in the proportion of YFP+ dorsal root ganglion neurons, which were immunoreactive for BDNF or trkB, as well as an increase in the length of regenerating axons through allografts from wild type litter mates, both 1 and 2 weeks later. Axon growth through allografts from neurotrophin‐4/5 knockout mice or grafts made acellular by repeated cycles of freezing and thawing is normally very poor, but electrical stimulation results in a growth of axons through these grafts, which is similar to that observed through grafts from wild type mice after electrical stimulation. When cut nerves in NT‐4/5 knockout mice were electrically stimulated, no enhancement of axon regeneration was found. Electrical stimulation thus produces a potent enhancement of the regeneration of axons in cut peripheral nerves, which is independent of neurotrophin production by cells in their surrounding environment but is dependent on stimulation of trkB and its ligands in the regenerating axons themselves. © 2006 Wiley Periodicals, Inc. Develop Neurobiol 67: 158–172, 2007.
Eph receptor and ephrin signaling in developing and adult brain of the honeybee (Apis mellifera)
Authors: Vidovic Maria , Nighorn Alan , Koblar Simon , Maleszka Ryszard 
Published: January 2007

AbstractRoles for Eph receptor tyrosine kinase and ephrin signaling in vertebrate brain development are well established. Their involvement in the modulation of mammalian synaptic structure and physiology is also emerging. However, less is known of their effects on brain development and their function in adult invertebrate nervous systems. Here, we report on the characterization of Eph receptor and ephrin orthologs in the honeybee, Apis mellifera (Am), and their role in learning and memory. In situ hybridization for mRNA expression showed a uniform distribution of expression of both genes across the developing pupal and adult brain. However, in situ labeling with Fc fusion proteins indicated that the AmEphR and Amephrin proteins were differentially localized to cell body regions in the mushroom bodies and the developing neuropiles of the antennal and optic lobes. In adults, AmEphR protein was localized to regions of synaptic contacts in optic lobes, in the glomeruli of antennal lobes, and in the medial lobe of the mushroom body. The latter two regions are involved in olfactory learning and memory in the honeybee. Injections of EphR‐Fc and ephrin‐Fc proteins into the brains of adult bees, 1 h before olfactory conditioning of the proboscis extension reflex, significantly reduced memory 24 h later. Experimental amnesia in the group injected with ephrin‐Fc was apparent 1 h post‐training. Experimental amnesia was also induced by post‐training injections with ephrin‐Fc suggesting a role in recall. This is the first demonstration that Eph molecules function to regulate the formation of memory in insects. © 2006 Wiley Periodicals, Inc. Develop Neurobiol 67: 233–251, 2007.
Overexpression of Bcl‐2 or Bcl‐xL prevents spiral ganglion neuron death and inhibits neurite growth
Authors: Hansen Marlan R. , Roehm Pamela C. , Xu Ningyong , Green Steven H. 
Published: January 2007

AbstractSpiral ganglion neurons (SGNs) provide afferent innervation to the cochlea and rely on contact with hair cells (HCs) for their survival. Following deafferentation due to hair cell loss, SGNs gradually die. In a rat culture model, we explored the ability of prosurvival members of the Bcl‐2 family of proteins to support the survival and neurite outgrowth of SGNs. We found that overexpression of either Bcl‐2 or Bcl‐xL significantly increases SGN survival in the absence of neurotrophic factors, establishing that the Bcl‐2 pathway is sufficient for SGN cell survival and that SGN deprived of trophic support die by an apoptotic mechanism. However, in contrast to observations in central neurons and PC12 cells where Bcl‐2 appears to promote neurite growth, both Bcl‐2 and Bcl‐xL overexpression dramatically inhibit neurite outgrowth in SGNs. This inhibition of neurite growth by Bcl‐2 occurs in nearly all SGNs even in the presence of multiple neurotrophic factors implying that Bcl‐2 directly inhibits neurite growth rather than simply rescuing a subpopulation of neurons incapable of extending neurites without additional stimuli. Thus, although overexpression of prosurvival members of the Bcl‐2 family prevents SGN loss following trophic factor deprivation, the inhibition of neurite growth by these molecules may limit their efficacy for support of auditory nerve maintenance or regeneration following hair cell loss. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Locomotor activity is regulated by D2‐like receptors in Drosophila: An anatomic and functional analysis
Authors: Draper Isabelle , Kurshan Peri T. , McBride Edward , Jackson F. Rob , Kopin Alan S. 
Published: January 2007

AbstractIn mammals, dopamine 2‐like receptors are expressed in distinct pathways within the central nervous system, as well as in peripheral tissues. Selected neuronal D2‐like receptors play a critical role in modulating locomotor activity and, as such, represent an important therapeutic target (e.g. in Parkinson's disease). Previous studies have established that proteins required for dopamine (DA) neurotransmission are highly conserved between mammals and the fruit fly Drosophila melanogaster. These include a fly dopamine 2‐like receptor (DD2R; Hearn et al. PNAS 2002 99(22):14554) that has structural and pharmacologic similarity to the human D2‐like (D2R). In the current study, we define the spatial expression pattern of DD2R, and functionally characterize flies with reduced DD2 receptor levels. We show that DD2R is expressed in the larval and adult nervous systems, in cell groups that include the Ap‐let cohort of peptidergic neurons, as well as in peripheral tissues including the gut and Malpighian tubules. To examine DD2R function in vivo, we generated RNA‐interference (RNAi) flies with reduced DD2R expression. Behavioral analysis revealed that these flies show significantly decreased locomotor activity, similar to the phenotype observed in mammals with reduced D2R expression. The fly RNAi phenotype can be rescued by administration of the DD2R synthetic agonist bromocriptine, indicating specificity for the RNAi effect. These results suggest Drosophila as a useful system for future studies aimed at identifying modifiers of dopaminergic signaling/locomotor function. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Serotonin in a diencephalic nucleus controlling communication in an electric fish: Sexual dimorphism and relationship to indicators of dominance
Authors: Telgkamp Petra , Combs Nicole , Smith G. Troy 
Published: January 2007

AbstractSerotonin regulates aggressive behavior. The production or release of serotonin is sexually dimorphic and related to social rank in many species. We examined serotonin expression in the central posterior/prepacemaker nucleus (CP/PPn) of the electric fish Apteronotus leptorhynchus. The CP/PPn is a thalamic nucleus that controls agonistic and reproductive electrocommunication signals known as chirps and gradual frequency rises. In parts of the CP/PPn that control chirping, females had more than twice as many serotonergic fibers and terminals as did males. Serotonin immunoreactivity in chirp‐controlling areas of the CP/PPn was also negatively correlated with two indicators of dominance: electric organ discharge (EOD) frequency and body mass. Within sexes, the negative correlation between EOD frequency and serotonergic innervation of the PPn was significant in females, but not in males. Females with higher EOD frequencies had less serotonin in the CP/PPn than did females with lower EOD frequencies. Thus, the CP/PPn contained more serotonin in females than in males, and in particular, more serotonin in females with EOD frequencies typical of social subordinates than in females with EOD frequencies typical of social dominants. These results, combined with previous findings that serotonin inhibits chirping and that females chirp much less than males, suggest that serotonin may link sex, social rank, and the production of agonistic communication signals. The relative simplicity of the neural circuits that control the EOD and chirping make the electromotor system well‐suited for studying the cellular, physiological, and behavioral mechanisms by which serotonin modulates agonistic communication. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Efficient DNA Cleavage Induced by Copper(II) Complexes of Hydrolysis Derivatives of 2,4,6‐Tri(2‐pyridyl)‐1,3,5‐triazine in the Presence of Reducing Agents
Authors: Borrás Joaquín , Alzuet Gloria , González‐Alvarez Marta , García‐Giménez Jose L. , Macías Benigno , Liu‐González Malva 
Published: January 2007

AbstractThe reaction of 2,4,6‐tri(pyridyl)‐1,3,5‐triazine (ptz) and copper(II) salts in dmf/water (1:1) results in the hydrolysis of ptz and formation of the anions bis(2‐pyridylcarbonyl)amide (ptO2–) and bis(2‐pyridylamine)amide (ptN2–), which are found in the complexes [Cu(ptN2)(OAc)]·3H2O (1), [Cu(ptO2)(OAc)(H2O)]·H2O (2), [Cu(ptN2)(for)]·3H2O (3) (for = formate), [Cu(ptO2)(for)(H2O)] (4), [Cu(ptO2)(benz)]·H2O (5) (benz = benzoate), and [Cu(ptO2)F(H2O)]2·3H2O (6). This report includes the chemical and spectroscopic characterization of all these complexes along with the crystal structures of 4–6. The coordination spheres of CuII in 4 and 5 are best described as distorted tetragonal square pyramidal for the former and distorted square planar for the latter. The crystal structure of 6 shows the presence of two discrete monomeric [Cu(ptO2)F(H2O)] entities in the crystallographic asymmetric unit in which both copper(II) ions have a distorted square‐pyramidal coordination geometry. The binding of the complexes to DNA has been investigated with the aid of viscosity and thermal denaturation studies, both of which indicate that the interaction is probably due to the outer‐sphere mechanism. The ability of the compounds to cleave DNA has also been tested. Efficient oxidative cleavage was observed in the presence of a mild reducing agent (ascorbate) and dioxygen. Mechanistic studies with reactive oxygen species (ROS) scavengers confirm that hydrogen peroxide, the hydroxyl radical, singlet oxygen‐like species, and the superoxide anion are necessary diffusible intermediates in the scission process. A mechanism involving either the Fenton or theHaber–Weiss reaction plus the formation of copper oxene species is proposed for the DNA cleavage mediated by these compounds.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Preparation, Structure and Reactivity of Polynuclear Gold(I) Phosphanyl Alkanethiolates
Authors: Battisti Antonella , Bellina Oliver , Diversi Pietro , Losi Serena , Marchetti Fabio , Zanello Piero 
Published: January 2007

AbstractThe homoleptic gold(I) thiolates of formula [Au(SR)]n (R = CMe3, CH2CMe3, CH2CHMe2, CPh3) have been converted into their phosphane derivatives of general formula [Au(SR)(L)] (L = PMe3, PMe2Ph, PMePh2, PPh3) and [Au2(SR)2(dppe)] [dppe = 1,2‐bis(diphenylphosphanyl)ethane], which have been characterized by elemental analysis, mass spectrometry, 1H and 31P NMR spectroscopy and cyclic voltammetry. Complexes [Au(SCMe3)(PMePh2)] (1c), [Au2(SCMe3)2(dppe)] (1e) and [Au(SCH2CMe3)(PPh3)] (3d) have been characterized in the solid state by X‐ray diffraction: no aurophilic interactions have been found. The electrochemical behaviour of these phosphane thiolato derivatives shows two irreversible oxidation processes, the first of which involves 0.5 electrons per Au–SR. Chemical oxidation by [FeCp2]BF4 produces disulfide and cationic gold(I) complexes of formula [Au2(SR)(L)2][BF4] and [Au2(SR)(dppe)][BF4], characterized by elemental analysis, mass spectrometry and 1H and 31P NMR spectroscopy. All the complexes are presumably dimeric in the solid state as shown in the case of [Au4(SCMe3)2(dppe)2][BF4]2 (5e) and [Au4(SCH2CMe3)2(PMe3)4][BF4]2 (7a), which have been fully characterized by X‐ray diffraction. The aurophilic interactions form a structure of four gold atoms with pairs of atoms bonded by bridging thiolato ligands, which are arranged in an almost perfect square in the case of 7a and in an unprecedented zigzag sequence in the case of 5e. Complex 4a reacts with HSCMe3 under basic conditions to give [Au(SCMe3)(PMe3)] and with LiX (X = Me, CH2CMe3) to give a 1:1 mixture of [AuX(PMe3)] and [Au(SCMe3)(PMe3)].(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
An Efficient Synthesis of 7,8‐Dihydropyrimido[5,4‐d]pyrimidines
Authors: Carvalho M. Alice , Esperança Sandra , Esteves Teresa , Proença M. Fernanda 
Published: January 2007

Abstract7,8‐Dihydropyrimido[5,4‐d]pyrimidines 4 were isolated in very good yields by treatment of 9‐aryl‐6‐cyanopurines 1 with primary amines. Nucleophilic attack of the amine on C8 of the purine ring was followed by ring‐opening of the imidazole unit, and subsequent intramolecular cyclization involving the newly formed amidine group and the cyano substituent in the pyrimidine ring produced the 7,8‐dihydropyrimido[5,4‐d]pyrimidine structure 4. When ammonia was used instead of primary amines, compound 4 rapidly reacted further to afford the more stable pyrimido[5,4‐d]pyrimidine 6 as a result of tautomeric equilibration. The aromatic structure 6 was also isolated when purine 1a and an excess of ethanolamine were heated at reflux in methanol, and also whenpurine 1c was combined with an excess of (4‐methoxyphenyl)hydrazine in THF at room temperature in the presence of a catalytic amount of DBU. In both cases the product is formed by a Dimroth rearrangement of the precursor 7,8‐dihydropyrimido[5,4‐d]pyrimidine 4. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Formation of a Tetracyclic Isoquinoline Derivative by Rearrangement of a [(Bromophenyl)butyryl]oxazolidinone
Authors: Roydhouse Mark D. , Walton John C. 
Published: January 2007

AbstractTreatment of 3‐[4‐(2‐bromophenyl)‐2‐phenylbutyryl]‐4,4‐dimethyloxazolidin‐2‐one with LDA in THF launched a domino rearrangement sequence ending in the assembly of a tetracyclic cyclopentaoxazolo[3,2‐b]isoquinolin‐6‐one derivative. Two mechanisms involving an SRN1‐type process were proposed. EPR spectroscopic and13C‐labelling experiments suggested that both were operative.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Continuous measurement of sediment transport in the Erlenbach stream using piezoelectric bedload impact sensors
Authors: Rickenmann D. , McArdell B. W. 
Published: January 2007

AbstractWe report on bedload transport observations using piezoelectric bedload impact sensors (PBIS), an indirect method of estimating the volume of bedload transport of coarse sediment. The PBIS device registers vibrations produced by bedload (particle diameter >∼20 mm) and records the signal as a sum of the number of impulses per time. Sediment transport at the Erlenbach stream has been continuously monitored with a PBIS array starting in 1986. The sensor array spans the width of an entire cross‐section and is mounted flush with the surface of a check dam immediately upstream of a sediment retention basin. We compare PBIS data with long‐term sedimentation records obtained from repeated surveys of material stored in the sediment retention basin, with artificial sediment input under controlled conditions in the field, and also with laboratory experiments. The rate of bedload transport is proportional to the number of impacts on the sensor per unit time. The reliability of the calibration relationship increases with the length of the observation period, e.g. for higher numbers of impacts and larger bedload volumes. Sediment volumes for individual flood events estimated with the PBIS method are in agreement with volumes estimated using an independent empirical method based on the effective runoff volume of water, the peak water discharge, and the critical discharge for the onset of sediment transport. Copyright © 2007 John Wiley & Sons, Ltd.
Short‐term rock surface expansion and contraction in the intertidal zone
Authors: Porter Neil J. , Trenhaile A. S. 
Published: January 2007

AbstractTransverse micro‐erosion meter (TMEM) stations were installed in rock slabs from shore platforms in eastern Canada. The slabs were put into artificial sea water for 1, 6 or 11 hours, representing high, mid‐ and low tidal areas, respectively. The TMEMs were used to record changes in surface elevation as the rocks dried during the remainder of the 12 h of a semi‐diurnal tidal cycle. A similar technique was used on the same rock types at intertidal TMEM stations in the field, as the rocks dried during low tide. Argillite and basalt surface contraction was from 0 to 0·04 mm: there was little surface expansion. Sandstones contracted by up to 0·03 mm in the field, but there was almost no contraction in the laboratory. Argillite and basalt contraction tended to be greatest in the upper intertidal zone, and to increase with rates of longer‐term surface downwearing, but there was little relationship with rock hardness or air temperature and humidity. Changes in elevation at the same points at TMEM stations in the laboratory and field were quite consistent from one tidal cycle to the next, but there were considerable variations within single tidal cycles between different points within each station. The data suggest that contraction within the elevational zone that is normally submerged twice a day by the tides is by alternate wetting and drying. Short‐term changes in elevation are generally low compared with annual rates of downwearing owing to erosion, but they may generate stresses that contribute to rock breakdown. Copyright © 2007 John Wiley & Sons, Ltd.
Hydrodynamics in an expanded bed of large size ion‐exchange resin, and natural product adsorption
Authors: Chen Wei‐Dong , Wang Yan‐Dong , Hu Han‐Hua , Su Zhi‐Guo 
Published: January 2007

AbstractSuccessful applications of expanded bed adsorption (EBA) technology have been widely reported in the literature for protein purification. Little has been reported on the recovery of natural products and active components of Chinese herbal preparations using EBA technology. In this study, the hydrodynamic behavior in an expanded bed of cation resin, 001 × 7 Styrene‐DVB, was investigated. Ephedrine hydrochloride (EH) was used as a model natural product to test the dynamic binding capacity (DBC) in the expanded bed. EBA of EH directly from a feedstock containing powdered herbs has also been investigated. These particles are different from commercially available expanded bed adsorbents by virtue of their large size (205 to 1030 µm). When the adsorbent bed is expanded to approximately 1.3 to 1.5 times its settled bed height, the axial liquid‐phase dispersion coefficient was found to be of the order 10−5 m2 s−1, which falls into the range 1.0 × 10−6 to 1.0 × 10−5 m2 s−1 observed previously in protein purification. Because of the favorable column efficiency (low axial dispersion coefficient), the recovery yield and purification factor values of EH directly from a feedstock reached 86.5% and 18, respectively. The results suggest that EBA technology holds promise for the recovery of natural products and active components of Chinese herbal preparations. Copyright © 2007 Society of Chemical Industry
Degradation products formed from long‐chain PUFA during deodorization of fish oil
Authors: Fournier Véronique , Destaillats Frédéric , Lambelet Pierre , Dionisi Fabiola , Sébédio Jean‐Louis , Berdeaux Olivier 
Published: January 2007

AbstractOmega‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) are sensitive to heat and may be destroyed by thermal processes such as deodorization. For example, deodorization of fish oil may induce polymerization, geometrical isomerization and cyclization of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. In this paper, we review our main findings on the effects of deodorization at three different temperatures on semi‐refined fish oil LC‐PUFA. Cyclic structures have been elucidated and mechanisms responsible for ring formation have been discussed. Polymers were found to be the most abundant degradation products formed during fish oil deodorization. A method for quantitative measurement of geometrical isomers of EPA and DHA by gas‐liquid chromatography (GLC) has been developed and validated. Overall assessment of the results obtained with this method suggests that deodorization at temperatures above 180°C affects the quality and the content of LC‐PUFA in fish oil.