bluuebunny/crossref_metadata_2025 huggingface dataset:
The death of radical thought: from dispassionate to disinterested professionalism in intellectual labour
Authors: Lee Martyn
Published: May 2006

Much has been written on the role that the intellectual classes play as ‘workers’ within the reproduction of advanced capitalist systems of production. This article traces some of the salient developments of this group of workers during the twentieth century focusing on
their critical, although sometimes problematic, relation to capital. Using the seminal ideas of Aglietta, Lipietz and others associated with the French ‘regulation school’ I propose the idea that intellectual workers function as key agents within the mode of capitalist regulation,
most significantly as ‘cultural regulators’. The article goes on to suggest that there has been a significant drift in the status of this group following the demise of ‘Fordism’ and the emergence of new ‘post-Fordist’ economic configurations and their corresponding
‘promotional cultures’ throughout many advanced industrial nations. It is suggested that this shift marks a crucial realignment of notions of professionalism within the occupations and job prospects of the intellectual classes, signalling a move away from a ‘professional
radicalism’ in intellectual work towards a far more routinized and bureaucratic mode of labour. The article considers how this shift has impacted upon higher education within the context of the United Kingdom.
The hand that sets the table... The political economy and self-reflexive project of intellectual property law in relation to traditional knowledge
Authors: Hermanns Kwela Sabine
Published: May 2006

The article critically examines the political economy of intellectual property (IP), and the encounter within TRIPS between traditional knowledge holders and a Western-led international IP law regime that is turning ever more global. Patents, copyright and trade marks are protected
by intellectual property rights. The international regime which governs these is based on Western thinking around ownership and has most recently culminated in the Agreement on Trade Related Aspects of Intellectual Property Rights (TRIPS). TRIPS is an attempt to harmonize and enforce intellectual
property on a global scale. But this globalizing IP regime has difficulty accommodating the more localized interests of developing countries and indigenous communities who find themselves rich in traditional knowledge (TK). For a number of reasons, TK is not easily accommodated by Western
IP law categories. Therefore, TK often remains unprotected by law, and this can lead to uneven commercial and cultural exploitation of agricultural, medicinal and biodiversity-related knowledge, as well as of expressions of folklore in music, dance, song, designs, stories, artwork and handicraft.
The article calls for a renewed focus on moral philosophy in addressing the power relations and the negotiations between different IP interests. A brief history of Western IP law is included to illuminate these interests, and global IP law is challenged to develop novel self-reflexive identities
to reflect heterogeneity and difference. At the same time, the interests of traditional knowledge holders are discussed, and an attempt is made to group these into categories including articulations for remuneration, recognition, and return of traditional knowledge. The article suggests that
these various articulations themselves use, directly or indirectly, traditional Western categories of intellectual ownership and protection. The article further argues that in circumstances in which the international IP law regime is associated with an over-homogenized legal self-identity,
and with legal-legislative imperialist practices, a global regime should build cultural bridges and incorporate legal hybridities and heterogeneous identities.
Call for submission of Commentaries
Authors: Byerly Carolyn M.
Published: May 2006

The Commentaries within the International Journal of Media and Cultural Politics will be published to provoke thought and debate about the politics of media and cultural issues within and across nations. We also welcome responses to previously published commentaries and articles
in order to engage in a dialogue. This first issue kicks off with a collection of essays by scholars from around the world laying out their thinking about a range of issues related to media and cultural politics. In subsequent issues, pieces will be published in a specific Commentaries section
and will pick up on many of these themes, as well as other emerging concerns.
The architecture of post-industrialism: empire at Ground Zero
Authors: Mosco Vincent
Published: May 2006

At the end of World War II the United States was poised for empire. But in order to extend its imperial hegemony the United States would need to deepen it by solidifying the empire at home. Indeed, success in the war at home is a precondition for success abroad.
Introduction: Liberating images
Authors: Fisher Celeste A
Published: May 2006

Black women, particularly those of us who have chosen radical subjectivity, can move toward revolutionary social change that will address the diversity of our experiences and our needs. Collectively bringing our knowledge, resources, skills and wisdom to one another, we make the site where radical black female subjectivity can be nurtured and sustained.
Releasing the pursuit of bouncin' and behavin' hair: natural hair as an Afrocentric feminist aesthetic for beauty
Authors: White Shauntae Brown
Published: May 2006

Hair, like the issue of skin colour, carries much historical and social baggage in the African American community. Since slavery, the colour caste system within the African American community has perpetuated internalized racism and selfhatred. The system promotes a hierarchy that suggests
the more European one's features - the lighter one's skin, the less ethnic one's facial features and the straighter and longer one's hair - the greater one's social value. Since non-discursive phenomena are included in the scope of rhetoric, visual images, such as choice of hairstyles, are
rhetorical. Using an Afrocentric-feminist critical framing, I argue that some women who choose to wear their hair natural are making a rhetorical statement that resists Eurocentric standards of beauty while engaging in an act of self-definition and liberation. Since one of the primary interests
in both Afrocentric and black feminist criticism is to understand how oppression is constructed and eliminated, this study seeks to understand (1) how a Eurocentric standard of beauty is constructed and perpetuated in American culture and (2) how some women have challenged and transformed
this universal standard by the choice they make in how they wear their hair. This rhetorical analysis will provide an overview of the politics of hair in the African American community and apply an Afrocentric-black feminist critical lens to the narratives of fourteen women who have chosen
to wear their hair natural.
Reviews
Authors: Enli Gunn Sara , Jansen Sue Curry , Carter Cynthia
Published: May 2006

Entertaining the Citizen: When Politics and Popular Culture Converge, Liesbet van Zoonen, (2004) Lanham, MD: Rowman & Littlefield, 181 pp., ISBN 0742529061 (hbk), 69.00; ISBN 074252907X (pbk), 26.95.

Courting The Abyss: Free Speech and the Liberal Tradition,
John Durham Peters, (2005) Chicago and London: The University of Chicago Press, 316 pp., ISBN 0226662748 (hbk), 29.00.

Mixed Media: Feminist Presses and Publishing Politics, Simone Murray, (2004) London: Pluto Press, 260 pp., ISBN 0745320163 (hbk), 55.00; ISBN 0745320155
(pbk), 16.99.

Simone Murray's book looks at the contribution of the second wave feminist presses to the advancement of feminist ideas in the United Kingdom from the early 1970s to the first years of the twenty-first century. These presses, she claims, have profoundly reshaped the publishing
industries and the wider literary culture and education. To appreciate the complex interrelations between feminist politics, feminist presses, mainstream publishers, academic feminist publishing, and feminist bestsellers, Murray argues for the development of a publishing centred analysis.
This approach enables movement beyond a focus on individual texts so as to contextualize them within the dynamics of the broader publishing industry. Such presses have experienced great difficulties (most are now defunct). Moreover, many mainstream publishers now have extensive gender lists.
Nevertheless, Murray argues that feminist presses continue to be a crucial safeguard, against the vagaries of a publishing industry whose interest in feminist texts lies in their ability to generate profit rather than in any real commitment to a feminist political agenda.
Class analysis, culture and inequality in the information society
Authors: Butt Danny
Published: May 2006

This paper argues that class analysis contains important tools for understanding contemporary socio-economic inequality in the new media environment. For research seeking to promote the reduction of inequality, the Marxian class analytical tradition has two important features: (1) it
identifies collectively-held interests in contrast to the methodological individualism of neo-classical economics, thus providing a basis for political action; and (2) it understands those interests as relational and socially constituted, and therefore processual and able to be changed. Class
analysis has declined in effectiveness due to its failure to respond to critiques emanating from identity-based new social movements (e.g. feminism, anti-racism, etc.). These critiques have required universalist social theory such as classical Marxism to reflexively understand its cultural
and historical specificity. I argue that such an understanding is becoming possible through analysis of the role of information in the economy. The evidence suggests that the economy is fundamentally a cultural/informational entity, rather than a base for a cultural/ideological superstructure.
The paper sketches a revised class theory from a cultural perspective to yield a class analytical framework that will be useful for those excluded from the dominant networks of economic and cultural exchange.
Analysis of Knock-Out Mice to Determine the Role of HPC-1/Syntaxin 1A in Expressing Synaptic Plasticity
Authors: Fujiwara Tomonori , Mishima Tatsuya , Kofuji Takefumi , Chiba Tomoki , Tanaka Keiji , Yamamoto Akitsugu , Akagawa Kimio
Published: May 2006

The protein HPC-1/syntaxin 1A is abundantly expressed in neurons and localized in the neuronal plasma membrane. It forms a complex with SNAP-25 (25 kDa synaptosomal-associated protein) and VAMP-2 (vesicle-associated membrane protein)/synaptobrevin called SNARE (a solubleN-ethylmaleimide-sensitive fusion protein attachment protein receptor) complex, which is considered essential for synaptic vesicle exocytosis; thus, HPC-1/syntaxin 1A is considered crucial for synaptic transmission. To examine the physiological function of HPC-1/syntaxin 1Ain vivo, we produced knock-out (KO) mice by targeted gene disruption. Although HPC-1/syntaxin 1A expression was completely depleted without any effect on the expression of other SNARE proteins, the KO mice were viable. They grew normally, were fertile, and displayed no difference in appearance compared with control littermate. In cultured hippocampal neurons derived from the KO mice, the basic synaptic transmissionin vitrowas normal. However, the mutant mice had impaired long-term potentiation in the hippocampal slice. Also, although KO mice exhibited normal spatial memory in the hidden platform test, consolidation of conditioned fear memory was impaired. Interestingly, the KO mice had impaired conditioned fear memory extinction. These observations suggest that HPC-1/syntaxin 1A may be closely related to synaptic plasticity.
External Ions Are Coactivators of Kainate Receptors
Authors: Wong Adrian Y. C. , Fay Anne-Marie L. , Bowie Derek
Published: May 2006

The activation of ligand-gated ion channels is thought to depend solely on the binding of chemical neurotransmitters. In this study, we demonstrate that kainate (KA) ionotropic glutamate receptors (iGluRs) require not only the neurotransmitterl-glutamate (l-Glu) but also external sodium and chloride ions for activation. Removal of external ions traps KA receptors (KARs) in a novel inactive state that bindsl-Glu with picomolar affinity. Moreover, occupancy of KARs byl-Glu precludes external ion binding, demonstrating crosstalk between ligand- and ion-binding sites. AMPA iGluRs function normally in the absence of external ions, revealing that even closely related iGluR subfamilies operate by distinct gating mechanisms. This behavior is interchangeable via a single amino acid residue that operates as a molecular switch to confer AMPA receptor behavior onto KARs. Our findings identify a novel allosteric site that singles out KARs from all other ligand-gated ion channels.
Molecular Composition of the Endocannabinoid System at Glutamatergic Synapses
Authors: Katona István , Urbán Gabriella M. , Wallace Matthew , Ledent Catherine , Jung Kwang-Mook , Piomelli Daniele , Mackie Ken , Freund Tamás F.
Published: May 2006

Endocannabinoids play central roles in retrograde signaling at a wide variety of synapses throughout the CNS. Although several molecular components of the endocannabinoid system have been identified recently, their precise location and contribution to retrograde synaptic signaling is essentially unknown. Here we show, by using two independent riboprobes, that principal cell populations of the hippocampus express high levels of diacylglycerol lipase α (DGL-α), the enzyme involved in generation of the endocannabinoid 2-arachidonoyl-glycerol (2-AG). Immunostaining with two independent antibodies against DGL-α revealed that this lipase was concentrated in heads of dendritic spines throughout the hippocampal formation. Furthermore, quantification of high-resolution immunoelectron microscopic data showed that this enzyme was highly compartmentalized into a wide perisynaptic annulus around the postsynaptic density of axospinous contacts but did not occur intrasynaptically. On the opposite side of the synapse, the axon terminals forming these excitatory contacts were found to be equipped with presynaptic CB1cannabinoid receptors. This precise anatomical positioning suggests that 2-AG produced by DGL-α on spine heads may be involved in retrograde synaptic signaling at glutamatergic synapses, whereas CB1receptors located on the afferent terminals are in an ideal position to bind 2-AG and thereby adjust presynaptic glutamate release as a function of postsynaptic activity. We propose that this molecular composition of the endocannabinoid system may be a general feature of most glutamatergic synapses throughout the brain and may contribute to homosynaptic plasticity of excitatory synapses and to heterosynaptic plasticity between excitatory and inhibitory contacts.
A G-Protein-Coupled Estrogen Receptor Is Involved in Hypothalamic Control of Energy Homeostasis
Authors: Qiu Jian , Bosch Martha A. , Tobias Sandra C. , Krust Andree , Graham Sharon M. , Murphy Stephanie J. , Korach Kenneth S. , Chambon Pierre , Scanlan Thomas S. , Rønnekleiv Oline K. , Kelly Martin J.
Published: May 2006

Estrogens are involved in the hypothalamic control of multiple homeostatic functions including reproduction, stress responses, energy metabolism, sleep cycles, temperature regulation, and motivated behaviors. The critical role of 17β-estradiol (E2) is evident in hypoestrogenic states (e.g., postmenopause) in which many of these functions go awry. The actions of E2in the brain have been attributed to the activation of estrogen receptors α and β through nuclear, cytoplasmic, or membrane actions. However, we have identified a putative membrane-associated estrogen receptor that is coupled to desensitization of GABABand μ-opioid receptors in guinea pig and mouse hypothalamic proopiomelanocortin neurons. We have synthesized a new nonsteroidal compound, STX, which selectively targets the Gαq-coupled phospholipase C–protein kinase C–protein kinase A pathway, and have established that STX is more potent than E2in mediating this desensitization in an ICI 182, 780-sensitive manner in both guinea pig and mouse neurons. Both E2and STX were fully efficacious in estrogen receptor α,β knock-out mice. Moreover,in vivotreatment with STX, similar to E2, attenuated the weight gain in hypoestrogenic female guinea pigs. Therefore, this membrane-delimited signaling pathway plays a critical role in the control of energy homeostasis and may provide a novel therapeutic target for treatment of postmenopausal symptoms and eating disorders in females.
Brief Uncontrollable Stress Causes Dendritic Retraction in Infralimbic Cortex and Resistance to Fear Extinction in Mice
Authors: Izquierdo Alicia , Wellman Cara L. , Holmes Andrew
Published: May 2006

Extinction of conditioned fear responses is an active learning process resulting from the repeated presentation of a conditioned stimulus in the absence of the unconditioned aversive stimulus. Recent research implicates the medial prefrontal cortex (mPFC) in the mediation of fear extinction in rodents and the pathophysiology of posttraumatic stress disorder. However, there is currently little understanding of precisely how stress can impact fear extinction and the neural circuitry subserving this behavior. The present study examined the effects of brief exposure to an uncontrollable stressor on (1) fear conditioning and fear extinction, and (2) dendritic morphology of pyramidal neurons in the infralimbic (IL) and prelimbic (PL) regions of the mPFC in mice. Exposure to three episodes of stress ending 24 h before fear conditioning significantly attenuated the rate of cued fear extinction relative to nonstressed controls, but did not affect fear conditioning or cue or context recall. Analysis of Golgi-stained neurons showed that one or three exposures to daily swim stress caused significant retraction of terminal branches of apical, but not basilar, dendrites of IL neurons. In contrast, PL neuronal morphology was unaltered by stress. These data demonstrate that IL, but not PL, neurons are highly sensitive to even brief exposure to stress, and that this same form of stress impairs fear extinction. Present findings suggest that trauma may compromise the functional integrity of the mPFC with implications for the pathophysiology of certain neuropsychiatric disorders.
NMDA Receptor NR2 Subunit Dependence of the Slow Component of Magnesium Unblock
Authors: Clarke Richard J. , Johnson Jon W.
Published: May 2006

NMDA receptor activity is important for many physiological functions, including synapse formation and alterations in synaptic strength. NMDA receptors are composed most commonly of NR1 and NR2 subunits. There are four NR2 subunits (NR2A–NR2D). NR2 subunit expression varies across both brain regions and developmental stages. The identity of the NR2 subunit within a functional NMDA receptor helps to determine many pharmacological and biophysical receptor properties, including strength of block by external Mg2+(Mgo2+). Mgo2+block confers strong voltage dependence to NMDA receptor-mediated responses and is critically important for many of the functions that the NMDA receptor plays within the CNS. Here we describe the NR2 subunit dependence of the kinetics of Mgo2+unblock after rapid depolarizations. We find that Mgo2+unblocks from NR1/2A and NR1/2B receptors with a prominent slow component similar to that previously described in native hippocampal and cortical NMDA receptors. Strikingly, this slow component of Mgo2+unblock is completely absent from NR1/2C and NR1/2D receptors. Thus currents from NR1/2C and NR1/2D receptors respond more rapidly to fast depolarizations than currents from NR1/2A and NR1/2B receptors. In addition, the slow component of Mgo2+unblock from NR1/2B receptors is consistently slower than from NR1/2A receptors. This makes rapid depolarizations, such as action potential waveforms, more efficacious at stimulating Mgo2+unblock from NR1/2A than from NR1/2B receptors. These NR2 subunit differences in the kinetics of Mgo2+unblock are likely to help determine the contribution of each NMDA receptor subtype to current flow during synaptic activity.
Stress Increases Vulnerability to Inflammation in the Rat Prefrontal Cortex
Authors: de Pablos R. M. , Villarán R. F. , Argüelles S. , Herrera A. J. , Venero J. L. , Ayala A. , Cano J. , Machado A.
Published: May 2006

Inflammation could be involved in some neurodegenerative disorders that accompany signs of inflammation. However, because sensitivity to inflammation is not equal in all brain structures, a direct relationship is not clear. Our aim was to test whether some physiological circumstances, such as stress, could enhance susceptibility to inflammation in the prefrontal cortex (PFC), which shows a relative resistance to inflammation. PFC is important in many brain functions and is a target for some neurodegenerative diseases. We induced an inflammatory process by a single intracortical injection of 2 μg of lipopolysaccharide (LPS), a potent proinflammogen, in nonstressed and stressed rats. We evaluated the effect of our treatment on inflammatory markers, neuronal populations, BDNF expression, and behavior of several mitogen-activated protein (MAP) kinases and the transcription factor cAMP response element-binding protein. Stress strengthens the changes induced by LPS injection: microglial activation and proliferation with an increase in the levels of the proinflammatory cytokine tumor necrosis factor-α; loss of cells such as astroglia, seen as loss of glial fibrillary acidic protein immunoreactivity, and neurons, studied by neuronal-specific nuclear protein immunohistochemistry and GAD67 and NMDA receptor 1A mRNAs expression byin situhybridization. A significant increase in the BDNF mRNA expression and modifications in the levels of MAP kinase phosphorylation were also found. In addition, we observed a protective effect from RU486 [mifepristone (11β-[p-(dimethylamino)phenyl]-17β-hydroxy-17-(1-propynyl)estra-4,9-dien-3-one)], a potent inhibitor of the glucocorticoid receptor activation. All of these data show a synergistic effect between inflammation and stress, which could explain the relationship described between stress and some neurodegenerative pathologies.
Transcriptional Signatures of Cellular Plasticity in Mice Lacking the α1 Subunit of GABAAReceptors
Authors: Ponomarev Igor , Maiya Rajani , Harnett Mark T. , Schafer Gwen L. , Ryabinin Andrey E. , Blednov Yuri A. , Morikawa Hitoshi , Boehm Stephen L. , Homanics Gregg E. , Berman Ari , Lodowski Kerrie H. , Bergeson Susan E. , Harris R. Adron
Published: May 2006

GABAAreceptors mediate the majority of inhibitory neurotransmission in the CNS. Genetic deletion of the α1 subunit of GABAAreceptors results in a loss of α1-mediated fast inhibitory currents and a marked reduction in density of GABAAreceptors. A grossly normal phenotype of α1-deficient mice suggests the presence of neuronal adaptation to these drastic changes at the GABA synapse. We used cDNA microarrays to identify transcriptional fingerprints of cellular plasticity in response to altered GABAergic inhibition in the cerebral cortex and cerebellum of α1 mutants.In silicoanalysis of 982 mutation-regulated transcripts highlighted genes and functional groups involved in regulation of neuronal excitability and synaptic transmission, suggesting an adaptive response of the brain to an altered inhibitory tone. Public gene expression databases permitted identification of subsets of transcripts enriched in excitatory and inhibitory neurons as well as some glial cells, providing evidence for cellular plasticity in individual cell types. Additional analysis linked some transcriptional changes to cellular phenotypes observed in the knock-out mice and suggested several genes, such as the early growth response 1 (Egr1), small GTP binding protein Rac1 (Rac1), neurogranin (Nrgn), sodium channel β4 subunit (Scn4b), and potassium voltage-gated Kv4.2 channel (Kcnd2) as cell type-specific markers of neuronal plasticity. Furthermore, transcriptional activation of genes enriched in Bergman glia suggests an active role of these astrocytes in synaptic plasticity. Overall, our results suggest that the loss of α1-mediated fast inhibition produces diverse transcriptional responses that act to regulate neuronal excitability of individual neurons and stabilize neuronal networks, which may account for the lack of severe abnormalities in α1 null mutants.
Nogo-A-Deficient Mice Reveal Strain-Dependent Differences in Axonal Regeneration
Authors: Dimou Leda , Schnell Lisa , Montani Laura , Duncan Carri , Simonen Marjo , Schneider Regula , Liebscher Thomas , Gullo Miriam , Schwab Martin E.
Published: May 2006

Nogo-A, a membrane protein enriched in myelin of the adult CNS, inhibits neurite growth and regeneration; neutralizing antibodies or receptor blockers enhance regeneration and plasticity in the injured adult CNS and lead to improved functional outcome. Here we show that Nogo-A-specific knock-outs in backcrossed 129X1/SvJ and C57BL/6 mice display enhanced regeneration of the corticospinal tract after injury. Surprisingly, 129X1/SvJ Nogo-A knock-out mice had two to four times more regenerating fibers than C57BL/6 Nogo-A knock-out mice. Wild-type newborn 129X1/SvJ dorsal root gangliain vitrogrew a much higher number of processes in 3 d than C57BL/6 ganglia, confirming the stronger endogenous neurite growth potential of the 129X1/SvJ strain. cDNA microarrays of the intact and lesioned spinal cord of wild-type as well as Nogo-A knock-out animals showed a number of genes to be differentially expressed in the two mouse strains; many of them belong to functional categories associated with neurite growth, synapse formation, and inflammation/immune responses. These results show that neurite regenerationin vivo, under the permissive condition of Nogo-A deletion, and neurite outgrowthin vitrodiffer significantly in two widely used mouse strains and that Nogo-A is an important endogenous inhibitor of axonal regeneration in the adult spinal cord.
Synapsin Utilization Differs among Functional Classes of Synapses on Thalamocortical Cells
Authors: Kielland Anders , Erisir Alev , Walaas S. Ivar , Heggelund Paul
Published: May 2006

Several proteins in nerve terminals participate in synaptic transmission between neurons. The synapsins, which are synaptic vesicle-associated proteins, have widespread distribution in the brain and are assumed essential for sustained recruitment of vesicles during high rates of synaptic transmission. We compared the role of synapsins in two types of glutamatergic synapses on thalamocortical cells in the dorsal lateral geniculate nucleus of mice: retinogeniculate synapses, which transmit primary afferent input at high frequencies and show synaptic depression, and corticogeniculate synapses, which provide modulatory feedback at lower frequencies and show synaptic facilitation. We used electrophysiological methods to determine effects of gene knock-out of synapsin I and II on short-term synaptic plasticity in paired-pulse, pulse-train, and posttetanic potentiation paradigms. The gene inactivation changed the plasticity properties in corticogeniculate, but not in retinogeniculate, synapses. Immunostaining with antibodies against synapsins in wild-type mice demonstrated that neither synapsin I nor II occurred in retinogeniculate terminals, whereas both occurred in corticogeniculate terminals. In GABAergic terminals, only synapsin I occurred. In corticogeniculate terminals of knock-out mice, the density of synaptic vesicles was reduced because of increased terminal size rather than reduced number of vesicles and the intervesicle distance was increased compared with wild-type mice. In the retinogeniculate terminals, no significant morphometric differences occurred between knock-out and wild-type mice. Together, this indicates that synapsin I and II are not present in the retinogeniculate terminals and therefore are not essential for sustained, high-rate synaptic transmission.
Amplitude and Kinetics of Action Potential-Evoked Ca2+Current and Its Efficacy in Triggering Transmitter Release at the Developing Calyx of Held Synapse
Authors: Yang Yi-Mei , Wang Lu-Yang
Published: May 2006

Action potentials (APs) play a crucial role in evoking Ca2+currents (ICa) through voltage-gated calcium channels (VGCCs) and transmitter release. During development and neuromodulation, both depolarization and repolarization phases of APs change, but how such changes affect the characteristics of ICaand its efficacy at central synapses is not clear. By paired voltage-clamp recordings of ICaand excitatory postsynaptic currents (IEPSC) with pseudo-APs and real APs, we examined these issues in the developing calyx of Held synapse of postnatal mice. We found that speeding the AP depolarization rate primarily reduces the number of activated VGCCs, whereas shortening the AP repolarization phase decreases the number of activated VGCCs and accelerates their kinetics. The ICa–IESPCrelationships are well predicted by the integral but not the amplitude of ICa, and exhibit development- and temperature-dependent shifts toward left, indicating an enhancement in downstream Ca2+coupling efficacy. Cross-correlation analyses of ICaand IEPSCevoked by real APs and pseudo-APs demonstrated that AP shortening in the half-width from 0.4 ms at postnatal day 8 (P8)–P12 to 0.27 ms at P16–P18 decreases ICaintegral by 36%, but increases IEPSCby 72% as a result of developmental upregulation in coupling efficacy. These counteracting actions maintain the release fraction evoked by an AP at ∼10% of the maximal quantal output. We suggest that AP narrowing is a critical adaptation for the calyx of Held synapse to control the quantal output per AP and is likely important for the efficient use of the readily releasable pool of synaptic vesicles during high-frequency neurotransmission.
alx, a Zebrafish Homolog ofChx10, Marks Ipsilateral Descending Excitatory Interneurons That Participate in the Regulation of Spinal Locomotor Circuits
Authors: Kimura Yukiko , Okamura Yasushi , Higashijima Shin-ichi
Published: May 2006

Recent molecular genetic studies suggest that the expression of transcription factors in the developing spinal cord helps determine the morphological and physiological properties of neurons. Using the zebrafish preparation, we have examined the properties of neurons marked byalx, a zebrafish homolog of mammalianChx10. We performed morphological and physiological studies using transgenic zebrafish expressing fluorescent reporter constructs in cells that had at any time point expressedalx(alxneurons). Our data reveal that zebrafishalxneurons are all ipsilateral descending neurons that are positive for vesicular glutamate transporter 2, suggesting that they are glutamatergic excitatory interneurons. Patch recordings show that earlier-born neurons are active during stronger movements such as escapes and fast swimming (strong movement class), whereas later-born ones are involved in sustained weak swimming (weak movement class). Paired recordings betweenalxneurons and motoneurons show that neurons of the strong movement class make frequent monosynaptic excitatory connections onto motoneurons. Thus, neurons of this class are likely premotor interneurons that regulate motoneuron activity during escapes and fast swimming. We also show the existence of a monosynaptic connection between analxneuron of the weak movement class and a motoneuron. Collectively, our data demonstrate thatalxmarks ipsilateral descending neurons that are involved in the regulation of motoneuron activity during forms of locomotion, such as escape and swimming.
Pronociceptive and Antinociceptive Effects of Estradiol through Endogenous Opioid Neurotransmission in Women
Authors: Smith Yolanda R. , Stohler Christian S. , Nichols Thomas E. , Bueller Joshua A. , Koeppe Robert A. , Zubieta Jon-Kar
Published: May 2006

Prominent interindividual and sex-dependent differences have been described in responses to sustained pain and other stressful stimuli. Variations in μ-opioid receptor-mediated endogenous opioid neurotransmission may underlie some of these processes. We examined both baseline μ-opioid receptor levels and the activation of this neurotransmitter system during sustained pain using positron emission tomography in a sample of young healthy men and women. Women were studied twice, during low and high estrogen states. The high-estrogen state was associated with regional increases in baseline μ-opioid receptor availabilityin vivoand a greater activation of endogenous opioid neurotransmission during the pain stressor. The latter did not differ from that obtained in males. During the low estrogen condition, however, significant reductions in endogenous opioid tone were observed at the level of thalamus, nucleus accumbens, and amygdala, which were associated with hyperalgesic responses. Estrogen-associated variations in the activity of μ-opioid neurotransmission correlated with individual ratings of the sensory and affective perceptions of the pain and the subsequent recall of that experience. These data demonstrate a significant role of estrogen in modulating endogenous opioid neurotransmission and associated psychophysical responses to a pain stressor in humans.
Functional and Selective RNA Interference in Developing Axons and Growth Cones
Authors: Hengst Ulrich , Cox Llewellyn J. , Macosko Evan Z. , Jaffrey Samie R.
Published: May 2006

Developing axons and growth cones contain “local” mRNAs that are translated in response to various extracellular signaling molecules and have roles in several processes during axonal development, including axonal pathfinding, orientation of axons in chemotactic gradients, and in the regulation of neurotransmitter release. The molecular mechanisms that regulate mRNA translation within axons and growth cones are unknown. Here we show that proteins involved in RNA interference (RNAi), including argonaute-3 and argonaute-4, Dicer, and the fragile X mental retardation protein, are found in developing axons and growth cones. These proteins assemble into functional RNA-induced silencing complexes as transfection of small interfering RNAs selectively into distal axons results in distal axon-specific mRNA knock-down, without reducing transcript levels in proximal axons or associated diffusion of small interfering RNA into proximal axons or cell bodies. RhoA mRNA is localized to axons and growth cones, and intra-axonal translation of RhoA is required for growth cone collapse elicited by Semaphorin 3A (Sema3A), an axonal guidance cue. Selective knock-down of axonal RhoA mRNA abolishes Sema3A-dependent growth cone collapse. Our results demonstrate functional and potent RNAi in axons and identify an approach to spatially regulate mRNA transcripts at a subcellular level in neurons.
Learning Cross-Modal Spatial Transformations through Spike Timing-Dependent Plasticity
Authors: Davison Andrew P. , Frégnac Yves
Published: May 2006

A common problem in tasks involving the integration of spatial information from multiple senses, or in sensorimotor coordination, is that different modalities represent space in different frames of reference. Coordinate transformations between different reference frames are therefore required. One way to achieve this relies on the encoding of spatial information with population codes. The set of network responses to stimuli in different locations (tuning curves) constitutes a set of basis functions that can be combined linearly through weighted synaptic connections to approximate nonlinear transformations of the input variables. The question then arises: how is the appropriate synaptic connectivity obtained? Here we show that a network of spiking neurons can learn the coordinate transformation from one frame of reference to another, with connectivity that develops continuously in an unsupervised manner, based only on the correlations available in the environment and with a biologically realistic plasticity mechanism (spike timing-dependent plasticity).
BDNF Is Expressed in Skeletal Muscle Satellite Cells and Inhibits Myogenic Differentiation
Authors: Mousavi Kambiz , Jasmin Bernard J.
Published: May 2006

In skeletal muscle, brain-derived neurotrophic factor (BDNF) has long been thought to serve as a retrograde trophic factor for innervating motor neurons throughout their lifespan. However, its localization in mature muscle fibers has remained elusive. Given the postulated roles of BDNF in skeletal muscle, we performed a series of complementary experiments aimed at defining the localization of BDNF and its transcripts in adult muscle. By reverse transcription-PCR,in situhybridization, and immunofluorescence, we show that BDNF, along with the receptor p75NTR, is not expressed at significant levels within mature myofibers and that it does not accumulate preferentially within subsynaptic regions of neuromuscular junctions. Interestingly, expression of BDNF correlated with that of Pax3, a marker of muscle progenitor cells, in several different adult skeletal muscles. Additionally, BDNF was expressed in Pax7+ satellite cells where it colocalized with p75NTR. In complementary cell culture experiments, we detected high levels of BDNF and p75NTRin myoblasts. During myogenic differentiation, expression of BDNF became drastically reduced. Using small interfering RNA (siRNA) technology to knock down BDNF expression, we demonstrate enhanced myogenic differentiation of myoblasts. This accelerated rate of myogenic differentiation seen in myoblasts expressing BDNF siRNA was normalized by administration of recombinant BDNF. Collectively, these findings show that BDNF plays an important regulatory function during myogenic differentiation. In addition, the expression of BDNF in satellite cells is coherent with the notion that BDNF serves a key role in maintaining the population of muscle progenitors in adult muscle.
Transient Suppression of Ipsilateral Primary Somatosensory Cortex during Tactile Finger Stimulation
Authors: Hlushchuk Yevhen , Hari Riitta
Published: May 2006

The whole human primary somatosensory (SI) cortex is activated by contralateral tactile stimuli, whereas its subarea 2 displays neuronal responses also to ipsilateral stimuli. Here we report on a transient deactivation of area 3b of the ipsilateral SI during long-lasting tactile stimulation.

We collected functional magnetic resonance imaging data with a 3 T scanner from 10 healthy adult subjects while tactile pulses were delivered at 1, 4, or 10 Hz in 25 s blocks to three right-hand fingers. In the contralateral SI cortex, activation [positive blood oxygenation level-dependent (BOLD) response] outlasted the stimulus blocks by 20 s, with an average duration of 45 s. In contrast, a transient deactivation (negative BOLD response) occurred in the ipsilateral rolandic cortex with an average duration of 18 s. Additional recordings on 10 subjects confirmed that the deactivation was not limited to the right SI but occurred in the SI cortex ipsilateral to the stimulated hand. Moreover, the primary motor cortex (MI) contained voxels that were phasically deactivated in response to both ipsilateral and contralateral touch.

These data indicate that unilateral touch of fingers is associated, in addition to the well known activation of the contralateral SI cortex, with deactivation of the ipsilateral SI cortex and of the MI cortex of both hemispheres. The ipsilateral SI deactivation could result from transcallosal inhibition, whereas intracortical SI–MI connections could be responsible for the MI deactivation. The shorter time course of deactivation than activation would agree with stronger decay of inhibitory than EPSP at the applied stimulus repetition rates.
Regelung adaptronischer Systeme, Teil I: Piezoelektrische Strukturen (Control of Adaptronic Systems, Part I: Piezoelectric Structures)
Authors: Kugi Andreas , Thull Daniel , Meurer Thomas
Published: May 2006

Dieser Beitrag setzt sich aus zwei Teilen zusammen und beschäftigt sich mit der Regelung adaptronischer Systeme anhand von zwei konkreten Anwendungen, nämlich einer piezoelektrischen Verbundstruktur im Teil I und einem elektrorheologischen Aktor im Teil II. Nach einer ausführlichen Übersicht über die systemtheoretischen Konzepte zur Regelung piezoelektrischer Strukturen widmet sich dieser erste Teil dem Problem der Trajektorienfolgeregelung für einen Trimorph Kragbalken mit Endmasse. Dabei ist es das Ziel, eine Regelung so zu entwerfen, dass innerhalb der technisch möglichen Grenzen die Auslenkung und der Winkel der Endmasse gleichzeitig und möglichst entkoppelt entlang vorgegebener Solltrajektorien geführt werden. Der Reglerentwurf basiert dabei direkt auf der partiellen Differenzialgleichung des Verbundbalkens und nutzt die Theorie der flachheitsbasierten Vorsteuerung in Kombination mit einer passivitätsbasierten Stabilisierung des Trajektorienfehlersystems. Die Brauchbarkeit des hier vorgestellten Konzeptes wird anhand von Simulationsstudien unter Zugrundelegung der Parameter eines kommerziell erhältlichen Trimorph Piezobiegers demonstriert.
Simulation of Adaptronic Structures (Simulation adaptronischer Strukturen)
Authors: Baier Horst , Müller Uwe
Published: May 2006

Adaptronic structures contain integrated sensors, actuators and controllers. Their structural behaviour is triggered by a controller in such a way that the deformations and vibrations are as close as possible to the required ones. Here, typical steps in modelling and simulation of such adaptive structures are given together with some results obtained for a practical example of a large astronomical telescope.
Adaptronic Systems for Aerospace Applications (Adaptronische Systeme für Anwendungen in der Luftfahrt)
Authors: Boller Christian
Published: May 2006

An overview of different activities related to the application of adaptronics is given, which includes structural health monitoring, shape control and active flow, damping of vibration and noise, and smart skins. Micro aerial vehicles are described as an interesting adaptronics demonstrator platform with aerospace in general being vigorously showing where adaptronics can be applied.
Preferential Solvation Effects on the Kinetics and Thermodynamics of Oxidation of Anilines by Chromium(VI)
Authors: Bhuvaneshwari D. S. , Elango K. P.
Published: May 2006

The imidazolium fluorochromate (IFC) oxidation of fifteen meta - and para-substituted anilines, in varying mole fractions of benzene in 2-methylpropan-2-ol as mixtures, in the presence of p-toluenesulfonic acid (TsOH) is first order in IFC and TsOH and zero order in substrate. The various thermodynamic parameters for the oxidation have been reported and discussed. The validity of the isokinetic relationship and various linear free energy relationships have been tested and discussed. The activation free energy data failed to correlate with macroscopic solvent parameters such as εr and E
T
N. Correlation of Δ G
# with Kamlet–Taft solvatochromic parameters (α, β and π*) suggests that the specific solute–solvent interactions play a major role in governing the reactivity.
Study on the Structure Transition of CTAB/1-Butanol/Heptane/Water Microemulsions by Pt Ultramicroelectrode
Authors: Li Ling , Lu Yao , Du Xigang , Yang Zhenyu , Yang Zhengyu
Published: May 2006

Ultramicroelectrode voltammetric measurements have been used in the microemulsions of CTAB/1-butanol/heptane/water to calculate the diffusion coefficient which can reflect the structure transition of the microemulsions. It is found that with increasing water content of microemulsions, the apparent diffusion coefficient (D
app) of the probe decreases monotonically with three transition points. The first two transition points indicate the change in the structure of microemulsions, that is from water in oil region to bicontinuous phase and then to oil in water region, while the third one differs from previous reports. The time resolved fluorescence quenching (TRFQ) technique has been carried out to obtain the aggregation number of the microemulsions in order to analyze the abnormal transition point. According to the TRFQ experiment, we find that the aggregation number of the microemulsion decrease with water content increasing between 50%–60%, and then tend to identical. These results suggest that the last transition point of the diffusion coefficient is because of the forces between oil droplets. The self-diffusion coefficient of oil droplet in the o/w region is calculated simultaneously. Based on these experimental results, we analyze the composition of the interface between oil and water.
FTIR Study of Molecular Interaction in Butyl Methacrylate–Organic Solvents Mixtures
Authors: Dharmalingam K. , Ramachandran K. , Sivagurunathan P.
Published: May 2006

FTIR spectroscopic study of butyl methacrylate (BMA) in different pure organic solvents were undertaken to investigate the solute–solvent interactions. The frequency of carbonyl stretching vibration ν(C=O) of BMA is correlated with the solvent properties such as the KBM parameter, the solvent acceptor number (AN), and the linear salvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with LSER parameters than AN. While no linear correlation between dielectric constants and the frequencies showed that the KBM relationship was unsuitable for this molecule. Also the solvent effect on the strength of hydrogen bond formation between free OH group of 1-butanol and C=O group of BMA is discussed in terms of local specific interaction between the solute and solvent.
The Difference in Entropy Between a Stable and Metastable Phase as the Temperature Approaches Zero Kelvin
Authors: Wolf B. M. A. van der
Published: May 2006

The free energy of two different phases not in equilibrium at the limit of zero Kelvin must be different. This difference in free energy can be related to the enthalpy and entropy, resulting in a general relation between the transition entropy and enthalpy at the limit of zero Kelvin.
Synthesis, Structure, Electrical and Magnetic Properties of Li Substituted La/BaMnO3–δ
Authors: El-Sayed A. M. , Khalil M. Sh.
Published: May 2006

The characterization of the polycrystalline La0.7Ba0.3MnO3-δ (LBM) and La0.7Ba0.3Mn0.9Li0.1O3-δ (LBMLi) samples synthesized via the polymerized complex, sol-gel technique indicates the formation of cubic perovskite crystal structure of both samples by sintering at 900ºC for 2h. Substitution of Mn by Li having smaller ionic radius, leads to decrease the lattice constant and the cell volume which gives rise to a small shift and small intensity difference of the XRD patterns. A nanocrystalline structure of LBMLi with particles in the size range of 30–100nm was obtained. The temperature dependence of electrical conductivity and magnetic susceptibility of LBM and LBMLi were studied. The smaller electrical conductivity values and the calculated magnetic properties of Li substituted the Mn in LBM sample were investigated.
A NMR Study on the Interactions of 1-Alkyl-3-Methylimidazolium Ionic Liquids with Acetone
Authors: Zhai Cuiping , Wang Jianji , Zhao Yang , Tang Junming , Wang Hanqing
Published: May 2006

1H and 13C NMR chemical shifts have been determined to investigate the interactions of acetone with room temperature ionic liquids ([C4mim][PF6], [C6mim][PF6], [C8mim][PF6] and [C6mim][BF4]) at various acetone mole fractions. Changes in the chemical shifts of hydrogen and carbon atoms of the above systems indicated that hydrogen bonds were formed between the ring protons, the methyl and methylene next to the nitrogen of the ionic liquids and the carbonyl oxygen of the acetone molecules. The strength of hydrogen bond was found to be influenced not only by the type of the anion but also by the length of alkyl chain on the imidazolium ring of cations. At the same time, ab initio calculations have been performed to support the NMR results.