bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroscopic Investigation of Atmospheric-Pressure Counterflow Diffusion Flames Inhibited by Halons
Authors: McNesby K. L. , Daniel R. G. , Widder J. M. , Miziolek A. W.
Published: May 2005

Infrared spectra of atmospheric-pressure counterflow diffusion flames inhibited by halons (a contraction of halogenated hydrocarbons) and a few of their potential replacements are measured with the use of Fourier transform spectroscopy. Results are compared to spectra of similar flame systems examined at low pressure. It is shown that, for atmospheric-pressure counterflow diffusion methane/air flames inhibited by CF3Br, CF2H2, and CF4, the two major fluorine-containing combustion products are HF and CF2O. A correlation is shown between flame inhibition efficiency and CF2O formation for atmospheric-pressure counterflow diffusion flames inhibited by these halons. For low-pressure premixed flames inhibited by CF3Br, HF appears to be the only fluorine-containing combustion product, even at relative dopant levels 15 times higher than those capable of extinguishing atmospheric-pressure counterflow diffusion flames. The results of these experiments illustrate the need for flame inhibitant testing over a wide spectrum of flame conditions, while providing further evidence that, for atmospheric-pressure inhibition of real fires by halons, CF2O may be a good indicator of inhibitor efficiency when that inhibition is at least partly accomplished by chemical scavenging of reactive combustion intermediates.
Polymer Film Thickness Determination with a High-Precision Scanning Reflectometer
Authors: Shelley Paul H. , Booksh Karl S. , Burgess Lloyd W. , Kowalski Bruce R.
Published: May 2005

A fiber-optic-based optical low coherence reflectometer (OLCR) is used to measure the thickness of polyester films. The measurements are made on both stationary and moving films to show the feasibility of this technique in a process environment. Autocorrelation is used to extract useful data from raw reflectometry data, and a statistical analysis of the data from both moving and stationary films is done to help demonstrate the application of this method. Although the reflectometer is not optimally configured for process analysis, a reliable estimate of polymer film thickness is shown in less than one minute measurement time for the moving films.
Surface-Enhanced Fourier Transform Raman Scattering Study on the Adsorption Structure of an RNA Triple Helix at a Silver Electrode
Authors: Fang Ye , Bai Chunli , Wei Ying , Tang Youqi
Published: May 2005

In this research, we studied the adsorption structure of an RNA triplex, poly[rU]poly[rA]poly[rU], at a silver electrode by surface-enhanced Fourier transform Raman scattering (FT-SERS) spectroscopy and compared it to those of the corresponding single-stranded poly[rA] and duplex poly[rA] · poly[rU]. Some interesting phenomena have been observed. At the ex situ electrochemically roughened silver electrode, the SERS behavior of the duplex RNA is close to that of the single-stranded poly[rA], thereby indicating that the duplex RNA adsorbed at the electrode might be partly destabilized. However, on the highly positively charged surfaces, the SERS spectra revealed that the triplex was predominantly adsorbed at the electrode via the phosphate-moiety-directed mechanism, and thus the helical structure of the triplex molecules was well preserved; furthermore, since the electrode potential was set to approach the potential of zero charge (pzc) of the silver metal, in the spectral region between 1800 and 600 cm−1 the triplex gives rise to SERS spectra similar to those of the corresponding duplex, and also yields only two enhanced signals at 734 and 1382 cm−1, due to the ring-breathing and ring-vibration modes of the adsorbed adenine residues, respectively, along with the disappearance of some bands originating from the corresponding rU residues and phosphate groups. In fact, a dramatic transition of the SERS spectra of the triplex at the electrode was found to occur between −0.2 and −0.4 V. On the basis of the structural characteristics of triple-helical nucleic acids, we concluded that in this case there are two types of competitive adsorbed species—the triplex itself and the unpaired adenine residues in the incomplete region of the triplex RNA—which might be responsible for the unique potential-dependent transition.
Vaporization of Nonvolatile and Matrix-Isolated Molecules Using a Novel Laser Vaporization Technique
Authors: Fletcher T. Rick , Rekow Matt , Rogge Dwayne , Sammeth David
Published: May 2005

A technique is described which uses a laser-generated high-velocity polymer flyer to vaporize nonvolatile molecules and low-temperature matrix-isolated species. Morphology studies, time-of-flight measurements, static collection methods, and real-time laser-induced fluorescence were used to characterize the new vaporization technique. Cr(CO)6 in a mineral oil glass at 77 K, rhodamine dye, and naphthalene were vaporized in these experiments.
Contemporary artworks and art education
Authors: Zupancic Tomaz
Published: May 2005

First I try to define contemporary art education. I touch on the globalization process, postmodern theories, openness, popular culture, interculturalism, nonvisual art disciplines, transcending the canon of Western art, peace culture and the need to reject absolute rules in judging
contemporary art. I then read some examples of contemporary work. The reading of an installation by the Atlas Group explores the issue of individual authorship. The reading of Helena, by Marco Evaristti, engages with ethical issues in contemporary art. The reading of Oleg Kulik’s
performance of Pavlov’s Dog tries to establish the nature of Kulik’s ‘sin’. I also urge art educators not to introduce Leni Riefenstahl into classrooms. The article ends with a short reading of Fiona Tan’s video work Countenance, as shown in Documenta
11.
Multi-roled and skilled teachers of art
Authors: Räsänen Marjo
Published: May 2005

The aim of this article is to evoke discussion of the changing roles of generalist and specialist art educators in Finland. It explores ways in which art educators can integrate the roles of cultural worker, teacher, artist, and researcher as suggested by three case studies. First,
it describes pre-service classroom teachers’ memories of their art lessons in school and expectations of teaching art in the future. This data comes from a web discussion that took place at the University of Turku. Second, it reports how student teachers of art articulated their professional
identity during a course in qualitative research methods at the University of Art and Design, Helsinki. Finally, key issues arising from a debate about art educators’ professional identity that took place on the web pages of the Finnish Association of Art Teachers are summarized. In
each case, the challenge of multiple roles is explored and suggestions are offered for solving a particular dilemma.
SchoolArts: DBAE and multicultural art education in the United States of America
Authors: Kader Themina
Published: May 2005

This article discusses how articles written by art teachers in the magazine SchoolArts reflect developments in multicultural and discipline-based (DBAE) art education in the United States. SchoolArts, which has the largest readership of any art publication, reflects current
classroom practices. Examining the articles in SchoolArts over a period of 33 years revealed that art teachers continue to teach multicultural art education based on the ‘additive approach’, which concentrates on cultural events that occur throughout a calendar year. Discipline-based
art education has provided additional impetus for art teachers to write articles, in the form of lessons, about personal multicultural experiences. The article argues that, overall. articles on multicultural art in SchoolArts lack sufficient historical content and other pertinent information,
thus missing the very goal teachers are trying to fulfil – to make the curriculum more culturally diverse.
Communicating feelings through visual language. My visual art diary: how I am feeling today
Authors: Dancevic Mirjana Tomasevic
Published: May 2005

This project, conducted at the Potocnica Early Years Education Centre in Zagreb, Croatia, investigated drawing as a means of projecting children’s emotional condition. It was grounded in psychological and psychiatric theory and practice. The assumption underpinning the project
was that children ‘draw what they feel and not what they think or know’ (Nazor, 1998, p. 259); that is why drawings can be viewed as expressions of children’s wishes, fears and frustrations. It is assumed that children and grown-ups alike adapt lines and colours in their
drawings according to their actual feelings, moods and conditions. However, it is not possible to establish beyond doubt that there is a unique language of lines, shapes and colours relating to feelings. Consequently, one should be cautious about drawing conclusions about the real messages
a child is sending through colours or arrangement of objects.
Executive Insights: Exploring the Practical Effects of Country of Origin, Animosity, and Price–Quality Issues: Two Case Studies of Taiwan and Acer in China
Authors: Amine Lyn S. , Chao Mike C.H. , Arnold Mark J.
Published: May 2005

The authors review relevant literature and present two new case studies—one of Taiwan's country image campaign and the other of Acer's entry into global markets—to gain a further understanding of two related constructs, country of origin (from the field of international marketing) and animosity (from the field of consumer behavior). The authors formulate four research propositions and discuss them in reference to the two case studies. They show how the Taiwanese government has used various marketing and advertising strategies to create a positive country image and how Acer has mitigated negative country-of-origin effects and animosity in world markets, especially in China.
Postadolescent Changes in Regional Cerebral Protein Synthesis: AnIn VivoStudy in theFmr1Null Mouse
Authors: Qin Mei , Kang Julia , Burlin Thomas V. , Jiang Chunhui , Smith Carolyn Beebe
Published: May 2005

Methylation-induced transcriptional silencing of the fragile X mental retardation-1 (Fmr1) gene leads to absence of the gene product, fragile X mental retardation protein (FMRP), and consequently fragile X syndrome (FrX), an X-linked inherited form of mental retardation. Absence of FMRP inFmr1null mice imparts some characteristics of the FrX phenotype, but the precise role of FMRP in neuronal function remains unknown. FMRP is an RNA-binding protein that has been shown to suppress translation of certain mRNAsin vitro. We applied the quantitative autoradiographicl-[1-14C]leucine method to thein vivodetermination of regional rates of cerebral protein synthesis (rCPS) in adult wild-type (WT) andFmr1null mice at 4 and 6 months of age. Our results show a substantial decrease in rCPS in all brain regions examined between the ages of 4 and 6 months in both WT andFmr1null mice. Superimposed on the age-dependent decline in rCPS, we demonstrate a regionally selective elevation in rCPS inFmr1null mice. Our results suggest that the process of synaptic pruning during young adulthood may be reflected in decreased rCPS. Our findings support the hypothesis that FMRP is a suppressor of translation in brainin vivo.
Molecular Determinants of KCNQ (Kv7) K+Channel Sensitivity to the Anticonvulsant Retigabine
Authors: Schenzer Anne , Friedrich Thomas , Pusch Michael , Saftig Paul , Jentsch Thomas J. , Grötzinger Joachim , Schwake Michael
Published: May 2005

Epilepsy is caused by an electrical hyperexcitability in the CNS. Because K+channels are critical for establishing and stabilizing the resting potential of neurons, a loss of K+channels could support neuronal hyperexcitability. Indeed, benign familial neonatal convulsions, an autosomal dominant epilepsy of infancy, is caused by mutations inKCNQ2orKCNQ3K+channel genes. Because these channels contribute to the native muscarinic-sensitive K+current (M current) that regulates excitability of numerous types of neurons, KCNQ (Kv7) channel activators would be effective in epilepsy treatment. A compound exhibiting anticonvulsant activity in animal seizure models is retigabine. It specifically acts on the neuronally expressed KCNQ2-KCNQ5 (Kv7.2-Kv7.5) channels, whereas KCNQ1 (Kv7.1) is not affected. Using the differential sensitivity of KCNQ3 and KCNQ1 to retigabine, we constructed chimeras to identify minimal segments required for sensitivity to the drug. We identified a single tryptophan residue within the S5 segment of KCNQ3 and also KCNQ2, KCNQ4, and KCNQ5 as crucial for the effect of retigabine. Furthermore, heteromeric KCNQ channels comprising KCNQ2 and KCNQ1 transmembrane domains (attributable to transfer of assembly properties from KCNQ3 to KCNQ1) are retigabine insensitive. Transfer of the tryptophan into the KCNQ1 scaffold resulted in retigabine-sensitive heteromers, suggesting that the tryptophan is necessary in all KCNQ subunits forming a functional tetramer to confer drug sensitivity.
Tuft Calcium Spikes in Accessory Olfactory Bulb Mitral Cells
Authors: Urban Nathaniel N. , Castro Jason B.
Published: May 2005

The mammalian accessory olfactory system is critical for the detection and identification of pheromones and the representation of complex stimuli including sex, genetic relatedness, and individual identity. Mitral cells, the principal cells of the accessory olfactory bulb (AOB), receive monosynaptic input from the sensory periphery and already show highly specific response properties, firing selectively for combinations of genetic markers and gender-specific cues. Vomeronasal sensory neuron axons form synapses onto distal tuft-like branches of mitral cell primary dendrites. We have studied dendritic excitability and synaptic integration in AOB mitral cell dendrites, and we show that dendrites of accessory olfactory bulb mitral cells support action potential propagation and can fire regenerative spike-like events that are likely to contribute to the integration of inputs to these cells. These tuft spikes may be important for the specificity of AOB mitral cell responses.
Pallidal Origin of GABA Release within the Substantia Nigra Pars Reticulata during High-Frequency Stimulation of the Subthalamic Nucleus
Authors: Windels François , Carcenac Carole , Poupard Annie , Savasta Marc
Published: May 2005

High-frequency stimulation of the subthalamic nucleus (HFS-STN) is an effective treatment for alleviating the motor symptoms of parkinsonian patients. However, the neurochemical basis of its effects remains unknown. We showed previously that 1 h of HFS-STN in normal rats increases extracellular glutamate (Glu) level in the output nuclei of the STN, the globus pallidus (GP), and the substantia nigra pars reticulata (SNr), consistent with an increase in the activity of STN neurons. HFS-STN also increases GABA levels in the SNr, but the origin of this increase is unclear. We investigated the effectiveness of HFS-STN for improving Parkinson's disease symptoms, using intracerebral microdialysis to determine the extracellular Glu and GABA levels of the GP and SNr in response to HFS-STN in anesthetized hemiparkinsonian rats [6-hydroxydopamine lesion of the substantia nigra pars compacta (SNc)]. Basal levels of Glu and GABA in the GP and SNr were significantly higher in hemiparkinsonian than in intact rats. HFS-STN did not affect extracellular Glu level in the SNr of hemiparkinsonian rats but doubled the level of GABA. Ibotenic acid lesion of the GP abolished the increase in GABA levels in the SNr induced by HFS-STN in SNc-lesioned rats. These results provide neurochemical confirmation of the hyperactivity of the STN after dopaminergic denervation and suggest that the therapeutic effects of HFS-STN may result partly from the stimulation of pallidonigral fibers, thereby revealing a potential role for pallidal GABA in the inhibition of basal ganglial output structures during HFS-STN.
Mutually Exclusive Glomerular Innervation by Two Distinct Types of Olfactory Sensory Neurons Revealed in Transgenic Zebrafish
Authors: Sato Yuki , Miyasaka Nobuhiko , Yoshihara Yoshihiro
Published: May 2005

The olfactory epithelium of fish contains two major types of olfactory sensory neurons (OSNs) that are distinct morphologically (ciliated vs microvillous) and possibly functionally. Here, we found that these OSNs express different sets of signal transduction machineries: the ciliated OSNs express OR-type odorant receptors, cyclic nucleotide-gated channel A2 subunit, and olfactory marker protein (OMP), whereas the microvillous OSNs express V2R-type receptors and transient receptor potential channel C2 (TRPC2). To visualize patterns of axonal projection from the two types of OSNs to the olfactory bulb (OB), we generated transgenic zebrafish in which spectrally distinct fluorescent proteins are expressed in the ciliated and microvillous OSNs under the control ofOMPandTRPC2gene promoters, respectively. An observation of whole-mount OB in adult double-transgenic zebrafish revealed that the ciliated OSNs project axons mostly to the dorsal and medial regions of the OB, whereas the microvillous OSNs project axons to the lateral region of the OB. A careful histological examination of OB sections clarified that the axons from the two distinct types of OSNs target different glomeruli in a mutually exclusive manner. This segregation is already established at very early developmental stages in zebrafish embryos. These findings clearly demonstrate the relationships among cell morphology, molecular signatures, and axonal terminations of the two distinct types of OSNs and suggest that the two segregated neural pathways are responsible for coding and processing of different types of odor information in the zebrafish olfactory system.
Adaptation of Sensory Neurons to Hyalectin and Decorin Proteoglycans
Authors: Lemons Michele L. , Barua Suman , Abanto Michael L. , Halfter Willi , Condic Maureen L.
Published: May 2005

Proteoglycans are abundantly expressed in the pathways of developing and regenerating neurons, yet the responses of neurons to specific proteoglycans are not well characterized. We have shown previously that one chondroitin sulfate proteoglycan (CSPG), aggrecan, is potently inhibitory to sensory axon extension in short-term assays and that over time, embryonic neurons adapt to aggrecan-mediated inhibition through the transcriptional upregulation of integrin expression (Condic et al., 1999). Here, we have compared the response of embryonic sensory neurons to structurally distinct CSPGs that belong to either the hyalectin (or lectican) family of large, aggregating proteoglycans or the decorin (or small leucine-rich proteoglycan) family of smaller proteoglycans. Both of these structurally diverse proteoglycan families are expressed in developing embryos and inhibit outgrowth of embryonic sensory neurons in short-term cultures. These results document a previously uncharacterized inhibitory function for the decorin-family proteoglycan biglycan. Interestingly, embryonic neurons adapt to these diverse proteoglycans over time. Adaptation is associated with upregulation of select integrin α subunits in a proteoglycan-specific manner. Overexpression of specific integrin α subunits improves neuronal regeneration on some but not all decorin-family CSPGs, suggesting that neurons adapt to inhibition mediated by closely related proteoglycans using distinct mechanisms. Our findings indicate that CSPGs with diverse core proteins and distinct numbers of chondroitin sulfate substitution sites mediate a similar response in sensory neurons, suggesting that increased integrin expression may be an effective means of promoting axonal regeneration in the presence of diverse inhibitory proteoglycan speciesin vivo.
Multisensory Integration of Dynamic Faces and Voices in Rhesus Monkey Auditory Cortex
Authors: Ghazanfar Asif A. , Maier Joost X. , Hoffman Kari L. , Logothetis Nikos K.
Published: May 2005

In the social world, multiple sensory channels are used concurrently to facilitate communication. Among human and nonhuman primates, faces and voices are the primary means of transmitting social signals (Adolphs, 2003; Ghazanfar and Santos, 2004). Primates recognize the correspondence between species-specific facial and vocal expressions (Massaro, 1998; Ghazanfar and Logothetis, 2003; Izumi and Kojima, 2004), and these visual and auditory channels can be integrated into unified percepts to enhance detection and discrimination. Where and how such communication signals are integrated at the neural level are poorly understood. In particular, it is unclear what role “unimodal” sensory areas, such as the auditory cortex, may play. We recorded local field potential activity, the signal that best correlates with human imaging and event-related potential signals, in both the core and lateral belt regions of the auditory cortex in awake behaving rhesus monkeys while they viewed vocalizing conspecifics. We demonstrate unequivocally that the primate auditory cortex integrates facial and vocal signals through enhancement and suppression of field potentials in both the core and lateral belt regions. The majority of these multisensory responses were specific to face/voice integration, and the lateral belt region shows a greater frequency of multisensory integration than the core region. These multisensory processes in the auditory cortex likely occur via reciprocal interactions with the superior temporal sulcus.
Endogenous κ-Opioid Receptor Systems Regulate Mesoaccumbal Dopamine Dynamics and Vulnerability to Cocaine
Authors: Chefer Vladimir I. , Czyzyk Traci , Bolan Elizabeth A. , Moron Jose , Pintar John E. , Shippenberg Toni S.
Published: May 2005

Genetic and pharmacological approaches were used to examine κ-opioid receptor (KOR-1) regulation of dopamine (DA) dynamics in the nucleus accumbens and vulnerability to cocaine. Microdialysis revealed that basal DA release and DA extraction fraction (Ed), an indirect measure of DA uptake, are enhanced in KOR-1 knock-out mice. Analysis of DA uptake revealed a decreasedKmbut unchangedVmaxin knock-outs. Knock-out mice exhibited an augmented locomotor response to cocaine, which did not differ from that of wild-types administered a behavioral sensitizing cocaine treatment. The ability of cocaine to increase DA was enhanced in knock-outs, whereas c-fos induction was decreased. Although repeated cocaine administration to wild types produced behavioral sensitization, knock-outs exhibited no additional enhancement of behavior. Administration of the long-acting KOR antagonist nor-binaltorphimine to wild-type mice increased DA dynamics. However, the effects varied with the duration of KOR-1 blockade. Basal DA release was increased whereasEdwas unaltered after 1 h blockade. After 24 h, release andEdwere increased. The behavioral and neurochemical effects of cocaine were enhanced at both time points.

These data demonstrate the existence of an endogenous KOR-1 system that tonically inhibits mesoaccumbal DA neurotransmission. Its loss induces neuroadaptations characteristic of “cocaine-sensitized” animals, indicating a critical role of KOR-1 in attenuating responsiveness to cocaine. The increased DA uptake after pharmacological inactivation or gene deletion highlights the plasticity of mesoaccumbal DA neurons and suggests that loss of KOR-1 and the resultant disinhibition of DA neurons trigger short- and long-term DA transporter adaptations that maintain normal DA levels, despite enhanced release.
The Functional Divide for Primary Reinforcement of D-Amphetamine Lies between the Medial and Lateral Ventral Striatum: Is the Division of the Accumbens Core, Shell, and Olfactory Tubercle Valid?: Figure 1.
Authors: Ikemoto Satoshi , Qin Mei , Liu Zhong-Hua
Published: May 2005

When projection analyses placed the nucleus accumbens and olfactory tubercle in the striatal system, functional links between these sites began to emerge. The accumbens has been implicated in the rewarding effects of psychomotor stimulants, whereas recent work suggests that the medial accumbens shell and medial olfactory tubercle mediate the rewarding effects of cocaine. Interestingly, anatomical evidence suggests that medial portions of the shell and tubercle receive afferents from common zones in a number of regions. Here, we report results suggesting that the current division of the ventral striatum into the accumbens core and shell and the olfactory tubercle does not reflect the functional organization for amphetamine reward. Rats quickly learned to self-administerd-amphetamine into the medial shell or medial tubercle, whereas they failed to learn to do so into the accumbens core, ventral shell, or lateral tubercle. Our results suggest that primary reinforcement of amphetamine is mediated via the medial portion of the ventral striatum. Thus, the medial shell and medial tubercle are more functionally related than the medial and ventral shell or the medial and lateral tubercle. The current core-shell-tubercle scheme should be reconsidered in light of recent anatomical data and these functional findings.
Regulation of NMDA Receptors by Neuregulin Signaling in Prefrontal Cortex
Authors: Gu Zhenglin , Jiang Qian , Fu Amy K. Y. , Ip Nancy Y. , Yan Zhen
Published: May 2005

Recent linkage studies have identified a significant association of the neuregulin gene with schizophrenia, but how neuregulin is involved in schizophrenia is primarily unknown. Aberrant NMDA receptor functions have been implicated in the pathophysiology of schizophrenia. Therefore, we hypothesize that neuregulin, which is present in glutamatergic synaptic vesicles, may affect NMDA receptor functions via actions on its ErbB receptors enriched in postsynaptic densities, hence participating in emotional regulation and cognitive processes that are impaired in schizophrenia. To test this, we examined the regulation of NMDA receptor currents by neuregulin signaling pathways in prefrontal cortex (PFC), a prominent area affected in schizophrenia. We found that bath perfusion of neuregulin significantly reduced whole-cell NMDA receptor currents in acutely isolated and cultured PFC pyramidal neurons and decreased NMDA receptor-mediated EPSCs in PFC slices. The effect of neuregulin was mainly blocked by application of the ErbB receptor tyrosine kinase inhibitor, phospholipase C (PLC) inhibitor, IP3receptor (IP3R) antagonist, or Ca2+chelators. The neuregulin regulation of NMDA receptor currents was also markedly attenuated in cultured neurons transfected with mutant forms of Ras or a dominant-negative form of MEK1 (mitogen-activated protein kinase kinase 1). Moreover, the neuregulin effect was prevented by agents that stabilize or disrupt actin polymerization but not by agents that interfere with microtubule assembly. Furthermore, neuregulin treatment increased the abundance of internalized NMDA receptors in cultured PFC neurons, which was also sensitive to agents affecting actin cytoskeleton. Together, our study suggests that both PLC/IP3R/Ca2+and Ras/MEK/ERK (extracellular signal-regulated kinase) signaling pathways are involved in the neuregulin-induced reduction of NMDA receptor currents, which is likely through enhancing NR1 internalization via an actin-dependent mechanism.
Estradiol Activates Group I and II Metabotropic Glutamate Receptor Signaling, Leading to Opposing Influences on cAMP Response Element-Binding Protein
Authors: Boulware Marissa I. , Weick Jason P. , Becklund Bryan R. , Kuo Sidney P. , Groth Rachel D. , Mermelstein Paul G.
Published: May 2005

In addition to mediating sexual maturation and reproduction through stimulation of classical intracellular receptors that bind DNA and regulate gene expression, estradiol is also thought to influence various brain functions by acting on receptors localized to the neuronal membrane surface. Many intracellular signaling pathways and modulatory proteins are affected by estradiol via this unconventional route, including regulation of the transcription factor cAMP response element-binding protein (CREB). However, the mechanisms by which estradiol acts at the membrane surface are poorly understood. Because both estradiol and CREB have been implicated in regulating learning and memory, we characterized the effects of estradiol on this transcription factor in cultured rat hippocampal neurons. Within minutes of administration, estradiol triggered mitogen-activated protein kinase (MAPK)-dependent CREB phosphorylation in unstimulated neurons. Furthermore, after brief depolarization, estradiol attenuated L-type calcium channel-mediated CREB phosphorylation. Thus, estradiol exhibited both positive and negative influences on CREB activity. These effects of estradiol were sex specific and traced to membrane-localized estrogen receptors that stimulated group I and II metabotropic glutamate receptor (mGluR) signaling. Activation of estrogen receptor α (ERα) led to mGluR1a signaling, triggering CREB phosphorylation through phospholipase C regulation of MAPK. In addition, estradiol stimulation of ERα or ERβ triggered mGluR2/3 signaling, decreasing L-type calcium channel-mediated CREB phosphorylation. These results not only characterize estradiol regulation of CREB but also provide two putative signaling mechanisms that may account for many of the unexplained observations regarding the influence of estradiol on nervous system function.
Camguk/CASK Enhances Ether-Á-Go-Go Potassium Current by a Phosphorylation-Dependent Mechanism
Authors: Marble Daniel D. , Hegle Andrew P. , Snyder Eric D. , Dimitratos Spiros , Bryant Peter J. , Wilson Gisela F.
Published: May 2005

Signaling complexes are essential for the modulation of excitability within restricted neuronal compartments. Adaptor proteins are the scaffold around which signaling complexes are organized. Here, we demonstrate that the Camguk (CMG)/CASK adaptor protein functionally modulatesDrosophilaEther-á-go-go (EAG) potassium channels. Coexpression of CMG with EAG inXenopusoocytes results in a more than twofold average increase in EAG whole-cell conductance. This effect depends on EAG-T787, the residue phosphorylated by calcium- and calmodulin-dependent protein kinase II (Wang et al., 2002). CMG coimmunoprecipitates with wild-type and EAG-T787A channels, indicating that T787, although necessary for the effect of CMG on EAG current, is not required for the formation of the EAG-CMG complex. Both CMG and phosphorylation of T787 increase the surface expression of EAG channels, and in COS-7 cells, EAG recruits CMG to the plasma membrane. The interaction of EAG with CMG requires a noncanonical Src homology 3-binding site beginning at position R1037 of the EAG sequence. Mutation of basic residues, but not neighboring prolines, prevents binding and prevents the increase in EAG conductance. Our findings demonstrate that membrane-associated guanylate kinase adaptor proteins can modulate ion channel function; in the case of CMG, this occurs via an increase in the surface expression and phosphorylation of the EAG channel.
Physiological Maturation of Photoreceptors Depends on the Voltage-Gated Sodium Channel NaV1.6 (Scn8a)
Authors: Côté Patrice D. , De Repentigny Yves , Coupland Stuart G. , Schwab Yannick , Roux Michel J. , Levinson S. Rock , Kothary Rashmi
Published: May 2005

Voltage-gated sodium channels (VGSCs) ensure the saltatory propagation of action potentials along axons by acting as signal amplifiers at the nodes of Ranvier. In the retina, activity mediated by VGSCs is important for the refinement of the retinotectal map. Here, we conducted a full-field electroretinogram (ERG) study on mice null for the sodium channel NaV1.6. Interestingly, the light-activated hyperpolarization of photoreceptor cells (the a-wave) and the major “downstream” components of the ERG, the b-wave and the oscillatory potentials, are markedly reduced and delayed in these mice. The functional deficit was not associated with any morphological abnormality. We demonstrate thatScn8ais expressed in the ganglion and inner nuclear layers and at low levels in the outer nuclear layer beginning shortly before the observed ERG deficit. Together, our data reveal a previously unappreciated role for VGSCs in the physiological maturation of photoreceptors.
Selectivity of Canary HVC Neurons for the Bird's Own Song: Modulation by Photoperiodic Conditions
Authors: Del Negro Catherine , Lehongre Katia , Edeline Jean-Marc
Published: May 2005

To what extent seasonal factors modify the neuronal functional properties within the nuclei of the avian song system remains an open question. In adult songbirds, neurons of the song premotor nucleus HVC (used as a proper name) exhibit selective responses for the bird's own song (BOS). Here we examine whether, outside the breeding season, when songs are less stereotyped, HVC neurons of male canaries still respond selectively to the BOS produced during this period. In an initial experiment, single-unit recordings (n= 114) revealed that the neuronal selectivity for the current BOS was attenuated in males exposed to a short-day photoperiod (typical of the nonbreeding season) compared with that found in males exposed to a long-day photoperiod. In long-day conditions, 35% of the cells responded to the BOS, whereas only 12% did in short-day conditions; there were four times more selective cells (d′ > 1) in long-day than in short-day conditions.

To determine whether these effects were the consequence of differences in acoustic features between breeding and nonbreeding songs, neurons (n= 72) recorded in short-day conditions were tested with both a short-day BOS and a long-day BOS. A low percentage of neurons exhibited responses to short-day or to long-day BOS (11% for each song). Responses of putative interneurons (spike duration <0.4 ms) and of putative relay cells were similarly attenuated by the short-day conditions. These results strongly suggest that, in canary, rather than being a fixed property, the selectivity for the BOS moves along a continuum and peaks when the day length mimics the breeding conditions.
Tissue Inhibitor of Metalloproteinase-2 Promotes Neuronal Differentiation by Acting as an Anti-Mitogenic Signal
Authors: Pérez-Martínez Leonor , Jaworski Diane M.
Published: May 2005

Although traditionally recognized for maintaining extracellular matrix integrity during morphogenesis, the function of matrix metallo-proteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), in the mature nervous system is essentially unknown. Here, we report that TIMP-2 induces pheochromocytoma PC12 cell-cycle arrest via regulation of cell-cycle regulatory proteins, resulting in differentiation and neurite outgrowth. TIMP-2 decreases cyclins B and D expression and increases p21Cipexpression. Furthermore, TIMP-2 promotes cell differentiation via activation of the cAMP/Rap1/ERK (extracellular signal-regulated kinase) pathway. Expression of dominant-negative Rap1 blocks TIMP-2-mediated neurite outgrowth. Both the cell-cycle arrest and neurite outgrowth induced by TIMP-2 was independent of MMP inhibitory activity. Consistent with the PC12 cell data, primary cultures of TIMP-2 knock-out cerebral cortical neurons exhibit significantly reduced neurite length, which is rescued by TIMP-2. Thesein vitroresults were corroboratedin vivo. TIMP-2 deletion causes a delay in neuronal differentiation, as demonstrated by the persistence of nestin-positive progenitors in the neocortical ventricular zone. The interaction of TIMP-2 with α3β1 integrin in the cerebral cortex suggests that TIMP-2 promotes neuronal differentiation and maintains mitotic quiescence in an MMP-independent manner through integrin activation. The identification of molecules responsible for neuronal quiescence has significant implications for the ability of the adult brain to generate new neurons in response to injury and neurological disorders, such as Alzheimer's and Parkinson's diseases.
First-principle studies of the lattice dynamics of crystals, and related properties
Authors: Gonze Xavier , Rignanese Gian-Marco , Caracas Razvan
Published: May 2005

The crystal lattice is never rigid. Due to temperature, external fields or pressure, the nuclei vibrate, the lattice distorts, and instabilities can induce phase transitions. We review the basic concepts of density-functional perturbation theory, a computational method especially suited to determine from first-principles the microscopic parameters governing such behaviour. Then, we present the additional formalism leading to the following properties of minerals: the infra-red and Raman spectra; the prediction of (meta)stability or instability of a crystalline phase, based on the phonon spectrum; the computation of thermodynamics quantities like the free energy, entropy, specific heat; the atomic temperature factors. For each property, examples are given. When appropriate, we mention the computation of related properties, like dielectric tensor and Born effective charges that are needed to get infra-red spectra. Finally, we discuss briefly, on one hand, other applications of the density-functional perturbation theory, and, on the other hand, an alternative technique, the finite-difference computation of dynamical matrices.
First-principle study of materials involved in incommensurate transitions
Authors: Caracas Razvan , Gonze Xavier
Published: May 2005

We discuss the applicability of the density functional theory to the study of incommensurate crystals. After a brief introduction to these aperiodic but ordered materials we present several types of ab initio methodologies that are adequate in the context of incommensurate transitions and phases. We also give a survey of the corresponding applications, while providing two case studies: Pb2MgTeO6 and K2SeO4.
Ab initio theory of planetary materials
Authors: Oganov Artem R. , Price G. David , Scandolo Sandro
Published: May 2005

Ab initio simulations play an increasingly important role in the studies of deep planetary interiors. Here we review the current state of this field, concentrating on studies of the materials of the Earth’s deep interior (MgO—SiO2—FeO—Al2O3, Fe—Si—S—O) and of the interiors of giant planets (H—He system, H2O—CH4—NH3 system). In particular, novel phases and phase diagrams, insights into structural and electronic phase transitions, melting curves, thermoelasticity and the effects of impurities on physical properties of planet-forming materials are discussed.
GULP: Capabilities and prospects
Authors: Gale Julian D.
Published: May 2005

The current status and capabilities of the atomistic simulation code GULP are described. In particular, the differences between versions 1.3.2 and 3.0 are detailed, as well as a concise pointer to applications in computational crystallography.
The DL_POLY molecular dynamics package
Authors: Smith William , Todorov Ilian T. , Leslie Maurice
Published: May 2005

The DL_POLY package provides a set of classical molecular dynamics programs that have application over a wide range of atomic and molecular systems. Written for parallel computers they offer capabilities stretching from small systems consisting of a few hundred atoms running on a single processor, up to systems of several million atoms running on massively parallel computers with thousands of processors. In this article we describe the structure of the programs and some applications.
STM3: a chemistry visualization platform
Authors: Valle Mario
Published: May 2005

To support CSCS research users we built STM3, a software platform on which advanced chemistry visualization techniques can be integrated. Its main goal is not to replace existing tools, but to provide functionalities not covered by them. STM3’s unusual characteristic among chemistry visualization tools is its ability to combine chemistry and general visualization techniques in the same view. STM3 is built on top of a proven visualization environment (AVS/Express) that lets CSCS’s visualization staff concentrate its efforts on developing new technologies rather than investing time on graphical and user interface implementation issues.
Interaction of 2‐Hydroxy‐substituted Nile Red Fluorescent Probe with Organic Nitrogen Compounds
Authors: Sebök‐Nagy Krisztina , Miskolczy Zsombor , Biczók László
Published: May 2005

The fluorescent properties of 2‐hydroxy Nile red dye (HONR) proved to be highly sensitive to the basicity of hydrogen bond acceptors. Fluorescence quantum yields and fluorescence decay profiles were measured as the function of the concentration of organic nitrogen compounds in solvents of various polarities. The detailed mechanism and the kinetics of the fluorescence quenching were revealed with the combined analysis of the steady‐state and time‐resolved spectroscopic data. The relative contribution of the competing reaction steps was found to be very sensitive to the basicity of the additive and to solvent polarity. The most profound change appeared in the unimolecular deactivation pathways of the excited hydrogen‐bonded HONR, whereas the formation rate of this species varied to a lesser extent. The dissociation into excited HONR and ground‐state base was able to compete with the energy dissipation only when 2,4,6‐trimethylpyridine was used as hydrogen bond acceptor in toluene. The bimolecular quenching of the excited hydrogen‐bonded complex played significant role in apolar solvents. Proton displacement along the hydrogen bond in the excited complex led to excited ion pairs in polar media.
Circular Dichroism of the Photoreceptor Pigment Oxyblepharismin
Authors: Pieroni Osvaldo , Plaza Pascal , Mahet Mathilde , Angelini Nicola , Checcucci Giovanni , Malatesta Manuela , Martin Monique M. , Lenci Francesco
Published: May 2005

Circular dichroism (CD) was used to study the structure of oxyblepharismin (OxyBP), the photoreceptor chromophore for the photophobic response of the blue form of Blepharisma japonicum. Both the chromophore associated to its native protein and the free chromophore in ethanol solution were investigated. CD spectra in the far‐UV range indicate that OxyBP induces a slight increase in the α‐helix content of the protein matrix. CD spectra in the near‐UV and visible region of the spectrum show that OxyBP adopts a chiral conformation with a preferential geometry not only when associated to its protein matrix, but also when isolated and dissolved in ethanol. This experimental result is related to the existence of a high‐energy interconversion barrier between two enantiomeric structures of the molecule and discussed on the basis of an asymmetric biosynthesis of its precursor, blepharismin.
Syndecan‐1 Expression During the Formation of Junctional Epithelium
Authors: Dias Rubia A. , Shibata Shunichi , Hashimoto‐Uoshima Mariko , Podyma‐Inoue Katarzyna A. , Ishikawa Isao , Yanagishita Masaki
Published: May 2005

Background: Syndecans are cell surface heparan sulfate proteoglycans (PG) which can bind to and modulate the action of growth factors and extracellular matrix components (ECM). Syndecan‐ 1 has been shown to play important roles during early tooth development and wound healing and repair. Among diverse cells and tissues that comprise the periodontium, the junctional epithelium (JE) constitutes a region of significant anatomic and clinical importance, but the nature of inductive signals and molecules involved in its formation is still unclear. Therefore, this work examines if syndecan‐1 is associated with formation of JE, and the distribution of other syndecan family members in the epithelium.

Methods:In situ hybridization and immunohistochemical techniques were performed using oral tissues from 4‐day‐old to 10‐week‐old mice to investigate the expression of syndecan‐ 1, ‐2, ‐3 and ‐4 mRNAs and their corresponding proteins.

Results: Based on in situ hybridization experiments, all syndecan mRNAs were detected in sulcular epithelium (SE), gingival epithelium (GE), and JE with varying intensity and distribution. Syndecan‐1 immunostaining was localized on the cell surface while that of syndecan‐2 did not show clear membrane localization. Our experiments in the developing tooth demonstrated that syndecan‐1 protein followed characteristic patterns of expression during JE formation and that immunoreactivity for syndecan‐1 protein decreased with age when JE cells underwent terminal differentiation.

Conclusion: Results of syndecan‐1 mRNA and protein expression patterns suggested that this proteoglycan might be an important molecule during the formation of JE. J Periodontol 2005;76:696‐704.
Characteristics of Periodontal Microflora in Acute Myocardial Infarction
Authors: Doĝan Başak , Buduneli Eralp , Emingil Gülnur , Atilla Gül , Akilli Azem , Antinheimo Johanna , Lakio Laura , Asikainen Sirkka
Published: May 2005

Background: Periodontitis has been linked to increased risk of cardiovascular diseases. Systemic reactions associated with cardiovascular events may depend on characteristics of the subgingival microflora in periodontitis. Our objectives were to compare the numbers of cultivable bacteria, composition of subgingival microflora and clonal distribution of Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) in two groups of patients with generalized chronic periodontitis (GCP), one with an acute myocardial infarction (AMI‐GCP) and the other one without AMI (non–AMI‐GCP).

Methods: In all, 150 dentate individuals were screened for suitability to this study. Subgingival bacterial samples were collected from 11 AMI‐GCP and 11 non–AMI‐GCP patients who had been selected using strict inclusion criteria in an attempt to exclude confounding factors and to increase comparability of periodontal conditions by matching for periodontal probing depths and attachment levels. Culture methods were used to determine the total viable counts and occurrence and proportions of six periodontal bacterial species and yeasts. Polymerase chain reaction (PCR) technique was used to detect A. actinomycetemcomitans and Porphyromonas gingivalis (P. gingivalis). Intraspecies characterization of A. actinomycetemcomitans included serotyping and genotyping.

Results: The mean proportions of P. gingivalis (P = 0.05) and Tannerella forsythensis (T. forsythensis) (P = 0.01) were significantly lower, but the numbers of Micromonas micros (M. micros) and A. actinomycetemcomitans were up to nine times higher and the mean total number of cultivable bacteria per sample higher (P <0.01) in AMI‐GCP than in non–AMI‐GCP.

Conclusion: The findings that no target subgingival species were overrepresented but the total bacterial number was higher in AMI‐GCP than non–AMI‐GCP patients may provide support to the hypothesis that elevated numbers of bacteria in close vicinity to sterile parenteral area present a risk for systemic health.J Periodontol 2005;76:740‐748.