bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of matrix metalloproteinase MMP-9 on dendritic spine morphology
Authors: Michaluk Piotr , Wawrzyniak Marcin , Alot Przemyslaw , Szczot Marcin , Wyrembek Paulina , Mercik Katarzyna , Medvedev Nikolay , Wilczek Ewa , De Roo Mathias , Zuschratter Werner , Muller Dominique , Wilczynski Grzegorz M. , Mozrzymas Jerzy W. , Stewart Michael G. , Kaczmarek Leszek , Wlodarczyk Jakub
Published: September 2011

An increasing body of data has shown that matrix metalloproteinase-9 (MMP-9), an extracellularly acting, Zn2+-dependent endopeptidase, is important not only for pathologies of the central nervous system but also for neuronal plasticity. Here, we use three independent experimental models to show that enzymatic activity of MMP-9 causes elongation and thinning of dendritic spines in the hippocampal neurons. These models are: a recently developed transgenic rat overexpressing autoactivating MMP-9, dissociated neuronal cultures, and organotypic neuronal cultures treated with recombinant autoactivating MMP-9. This dendritic effect is mediated by integrin β1 signalling. MMP-9 treatment also produces a change in the decay time of miniature synaptic currents; however, it does not change the abundance and localization of synaptic markers in dendritic protrusions. Our results, considered together with several recent studies, strongly imply that MMP-9 is functionally involved in synaptic remodelling.
Comparative gene expression profiles for highly similar aggressive phenotypes in male and female cichlid fishes (Julidochromis)
Authors: Schumer Molly , Krishnakant Kavita , Renn Suzy C. P.
Published: September 2011

Julidochromis marlieri and Julidochromis transcriptus are two closely related Tanganyikan cichlids that have evolved different behavior and mating strategies since they diverged from their common ancestor. While J. transcriptus follows the ancestral pattern of male dominance, male-biased sexual size dimorphism and territoriality, the pattern is reversed in J. marlieri. In J. marlieri, females show all of these behavioral and morphological characteristics. This raises the question of whether female J. marlieri achieve the dominant phenotype by expressing the same genes as J. transcriptus males or whether novel brain gene expression patterns have evolved to produce a similar behavioral phenotype in the females of J. marlieri. This study used cDNA microarrays to investigate whether female J. marlieri and male J. transcriptus show conserved or divergent patterns of brain gene expression. Analysis of microarray data in both species showed certain gene expression patterns associated with sex role independent of gonadal sex and, to a lesser extent, gene expression patterns associated with sex independent of sex role. In general, these data suggest that while there has been substantial divergence in gene expression patterns between J. transcriptus and J. marlieri, we can detect a highly significant overlap for a core set of genes related to aggression in both species. These results suggest that the proximate mechanisms regulating aggressive behavior in J. transcriptus and J. marlieri may be shared.
Intra-retinal variation of opsin gene expression in the guppy (Poecilia reticulata)
Authors: Rennison Diana J. , Owens Gregory L. , Allison W. Ted , Taylor John S.
Published: September 2011

Although behavioural experiments demonstrate that colouration influences mate choice in many species, a complete understanding of this form of signalling requires information about colour vision in the species under investigation. The guppy (Poecilia reticulata) has become a model species for the study of colour-based sexual selection. To investigate the role of opsin gene duplication and divergence in the evolution of colour-based mate choice, we used in situ hybridization to determine where the guppy's nine cone opsins are expressed in the retina. Long wavelength-sensitive (LWS) opsins were more abundant in the dorsal retina than in the ventral retina. One of the middle wavelength-sensitive opsins (RH2-1) exhibited the opposite pattern, while the other middle wavelength-sensitive opsin (RH2-2) and the short wavelength-sensitive opsins (SWS1, SWS2A and SWS2B) were expressed throughout the retina. We also found variation in LWS opsin expression among individuals. These observations suggest that regions of the guppy retina are specialized with respect to wavelength discrimination and/or sensitivity. Intra-retinal variability in opsin expression, which has been observed in several fish species, might be an adaptation to variation in the strength and spectral composition of light entering the eye from above and below. The discovery that opsin expression varies in the guppy retina may motivate new behavioural experiments designed to study its role in mate choice.
Peripheral injury induces long-term sensitization of defensive responses to visual and tactile stimuli in the squid Loligo pealeii, Lesueur 1821
Authors: Crook Robyn J. , Lewis Trevor , Hanlon Roger T. , Walters Edgar T.
Published: September 2011

Survivable injuries are a common yet costly experience. The ability to sense and respond to noxious stimuli is an almost universal trait, and prolonged behavioral alterations, including sensitization to touch and other stimuli, may function to ameliorate fitness costs associated with injury. Cephalopods can modify their behavior by learned association with noxious electric shock, but non-associative alterations of behavioral responses after tissue injury have not been studied. The aim of this study was to make the first systematic investigations in any cephalopod of behavioral responses and alterations elicited by explicit, minor injury. By testing responsiveness in the longfin squid, Loligo pealeii, to the approach and contact of an innocuous filament applied to different parts of the body both before and after injury to the distal third of one arm, we show that a cephalopod expresses behavioral alterations persisting for at least 2 days after injury. These alterations parallel forms of nociceptive plasticity in other animals, including general and site-specific sensitization to tactile stimuli. A novel finding is that hyper-responsiveness after injury extends to visual stimuli. Injured squid are more likely to employ crypsis than escape in response to an approaching visual stimulus shortly after injury, but initiate escape earlier and continue escape behaviors for longer when tested from 1 to 48 h after injury. Injury failed to elicit overt wound-directed behavior (e.g. grooming) or change hunting success. Our results show that long-lasting nociceptive sensitization occurs in cephalopods, and suggest that it may function to reduce predation risk after injury.
Regulation of bat echolocation pulse acoustics by striatal dopamine
Authors: Tressler Jedediah , Schwartz Christine , Wellman Paul , Hughes Samuel , Smotherman Michael
Published: September 2011

The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg–1) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D1- and D2-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D2-type dopamine receptor agonist (Quinpirole) but not by a D1-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D2-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats.
Symmorphosis and the insect respiratory system: allometric variation
Authors: Snelling Edward P. , Seymour Roger S. , Runciman Sue , Matthews Philip G. D. , White Craig R.
Published: September 2011

Taylor and Weibel's theory of symmorphosis predicts that structures of the respiratory system are matched to maximum functional requirements with minimal excess capacity. We tested this hypothesis in the respiratory system of the migratory locust, Locusta migratoria, by comparing the aerobic capacity of the jumping muscles with the morphology of the oxygen cascade in the hopping legs using an intraspecific allometric analysis of different body mass (Mb) at selected juvenile life stages. The maximum oxygen consumption rate of the hopping muscle during jumping exercise scales as Mb1.02±0.02, which parallels the scaling of mitochondrial volume in the hopping muscle, Mb1.02±0.08, and the total surface area of inner mitochondrial membrane, Mb0.99±0.10. Likewise, at the oxygen supply end of the insect respiratory system, there is congruence between the aerobic capacity of the hopping muscle and the total volume of tracheoles in the hopping muscle, Mb0.99±0.16, the total inner surface area of the tracheoles, Mb0.99±0.16, and the anatomical radial diffusing capacity of the tracheoles, Mb0.99±0.18. Therefore, the principles of symmorphosis are upheld at each step of the oxygen cascade in the respiratory system of the migratory locust.
Spectral and duration sensitivity to light-at-night in ‘blind’ and sighted rodent species
Authors: Zubidat Abed E. , Nelson Randy J. , Haim Abraham
Published: September 2011

Light-at-night (LAN) has become a defining feature of human and animal ecosystems and may possibly compromise human and animal physiology and health. Spectral and acclimation duration (AD) sensitivity were compared between social voles (Microtus socialis) and ‘blind’ mole rats (Spalax ehrenbergi) in four increasing ADs (0, 1, 7 and 21 days) to LAN (1×30 min, 293 μW cm–2) of three different monochromatic lights [blue (479 nm), yellow (586 nm) and red (697 nm)]. Animals were sampled for urine and oxygen consumption (VO2) promptly after each LAN-AD. Urine samples were analyzed for production rate, urinary 6-sulfatoxymelatonin and urinary metabolites of adrenalin and cortisol. Overall, the blue light elicited the greatest effects on the biological markers of M. socialis, whereas similar effects were detected for S. ehrenbergi in response to red light. The increasing LAN-AD resulted in a dose-dependent decrement of all markers tested, except of stress hormones, which showed a direct positive correlation with LAN-AD. Our results suggest that: (1) photoperiod is an important cue for entraining physiological functions in the ‘blind’ S. ehrenbergi, which is essentially characterized by red-shifted sensitivity compared with the blue-shifted sensitivity detected for the sighted counterpart species, and (2) there is a strong association between LAN of the appropriate wavelength and adrenal endocrine responses, suggesting that LAN is a potential environmental stressor.
Roles of biogenic amines in regulating bioluminescence in the Australian glowworm Arachnocampa flava
Authors: Rigby Lisa M. , Merritt David J.
Published: September 2011

The glowworm Arachnocampa flava is a carnivorous fly larva (Diptera) that uses light to attract prey into its web. The light organ is derived from cells of the Malpighian tubules, representing a bioluminescence system that is unique to the genus. Bioluminescence is modulated through the night although light levels change quite slowly compared with the flashing of the better-known fireflies (Coleoptera). The existing model for the neural regulation of bioluminescence in Arachnocampa, based on use of anaesthetics and ligations, is that bioluminescence is actively repressed during the non-glowing phase and the repression is partially released during the bioluminescence phase. The effect of the anaesthetic, carbon dioxide, on the isolated light organ from the present study indicates that the repression is at least partially mediated at the light organ itself rather than less directly through the central nervous system. Blocking of neural signals from the central nervous system through ligation leads to uncontrolled release of bioluminescence but light is emitted at relatively low levels compared with under anaesthesia. Candidate biogenic amines were introduced by several methods: feeding prey items injected with test solution, injecting the whole larva, injecting a ligated section containing the light organ or bathing the isolated light organ in test solution. Using these methods, dopamine, serotonin and tyramine do not affect bioluminescence output. Exposure to elevated levels of octopamine via feeding, injection or bathing of the isolated light organ indicates that it is involved in the regulation of repression. Administration of the octopamine antagonists phentolamine or mianserin results in very high bioluminescence output levels, similar to the effect of anaesthetics, but only mianserin acts directly on the light organ.
Fast-Food Consumption and the Ban on Advertising Targeting Children: The Quebec Experience
Authors: Dhar Tirtha , Baylis Kathy
Published: September 2011

Amid growing concerns about childhood obesity and the associated health risks, several countries are considering banning fast-food advertising targeting children. In this article, the authors study the effect of such a ban in the Canadian province of Quebec. Using household expenditure survey data from 1984 to 1992, authors examine whether expenditure on fast food is lower in those groups affected by the ban than in those that are not. The authors use a triple difference-indifference methodology by appropriately defining treatment and control groups and find that the ban's effectiveness is not a result of the decrease in fast food expenditures per week but rather of the decrease in purchase propensity by 13% per week. Overall, the authors estimate that the ban reduced fast-food consumption by Us$88 million per year. The study suggests that advertising bans can be effective provided media markets do not overlap.
The Role of Reciprocity in Clarifying the Performance Payoff of Relational Behavior
Authors: Hoppner Jessica J. , Griffith David A.
Published: September 2011

The authors theorize that the inconsistencies in prior research regarding the relational behavior–performance relationship arise from the type of reciprocity the firm internalizes. The results of a longitudinal study of 284 buyer–supplier relationships indicate that relational behavior enhances financial performance when what is exchanged does not need to be directly comparable with what was received (i.e., heteromorphic equivalence reciprocity) or can be returned over a longer time horizon (i.e., long-term immediacy reciprocity). Moreover, relational behavior diminishes financial performance when what is exchanged must be directly comparable in form (i.e., homeomorphic equivalence reciprocity) or returned over a short time horizon (i.e., short-term immediacy reciprocity). The authors further conclude that a longitudinal interaction effect model provides a more accurate understanding of the relational behavior–performance relationship when compared with a cross-sectional interaction effect model, because it minimizes the unobserved heterogeneity effect, thus strengthening causal inference.
Telocytes
Authors: Pellegrini Maria-Simonetta Faussone , Popescu Laurenţiu M.
Published: September 2011

Here, we review the history, morphology, immunohistochemical phenotype, and presumptive roles of a new type of interstitial tissue cells, formerly called interstitial Cajal-like cells (ICLC) and by 2010 named ‘telocytes’ (TC). Many different techniques have been used to characterize TC and provide their unequivocal identification: (i) in vitro, cultures and isolated cells; (ii) in situ, fixed specimens examined by light and fluorescence microscopy, transmission (TEM) and scanning electron microscopy, and electron tomography. TEM allowed sure identification and characterization of the most peculiar feature of TC: the long, thin, and convoluted prolongations named ‘telopodes’. An enormous variety of antibodies have been tested, but presently none are reliable to specifically label TC. TC have a mesenchymal origin and are resident connective tissue (stromal) cells. Possible identification with ‘already identified’ stromal cell types (fibroblasts, fibrocytes, fibroblast-like cells, and mesenchymal stromal cells) is discussed. We conclude that in adulthood, most of the TC have the morphology of fibrocytes. Apparently, immunocytochemistry suggests that a variety of TC populations showing different, likely organ-specific, immunophenotypes might exist. Several roles have been hypothesized for TC: mechanical roles, intercellular signaling, guiding and nursing of immature cells during organogenesis, and being themselves a pool of precursors for many of the mesenchyme-derived cells in adulthood; however, none of these roles have been proven yet. On the basis of the available data, we propose TC may be key players in organ regeneration and repair.
Calcineurin and Its Regulator Sra/DSCR1 Are Essential for Sleep inDrosophila
Authors: Nakai Yasuhiro , Horiuchi Junjiro , Tsuda Manabu , Takeo Satomi , Akahori Shin , Matsuo Takashi , Kume Kazuhiko , Aigaki Toshiro
Published: September 2011

Sleep is a fundamental biological process for all animals. However, the molecular mechanisms that regulate sleep are still poorly understood. Here we report that sleep-like behavior inDrosophilais severely impaired by mutations insarah(sra), a member of the Regulator of Calcineurin (RCAN) family of genes. Sleep reduction insramutants is highly correlated with decreases in Sra protein levels. Pan-neural expression ofsrarescues this behavioral phenotype, indicating that neuronalsrafunction is required for normal sleep. Since Sra regulates calcineurin (CN), we generated and examined the behavior of knock-out mutants for allDrosophilaCN genes:CanA-14F,Pp2B-14D, andCanA1(catalytic subunits), andCanBandCanB2(regulatory subunits). While all mutants show at least minor changes in sleep,CanA-14FKOandCanBKOhave striking reductions, suggesting that these are the major CN subunits regulating sleep. In addition, neuronal expression of constitutively active forms of CN catalytic subunits also significantly reduces sleep, demonstrating that both increases and decreases in CN activity inhibit sleep.srasleep defects are suppressed by CN mutations, indicating thatsraand CN affect sleep through a common mechanism. Our results demonstrate that CN and its regulation by Sra are required for normal sleep inDrosophilaand identify a critical role of Ca2+/calmodulin-dependent signaling in sleep regulation.
Variability of the Relationship between Electrophysiology and BOLD-fMRI across Cortical Regions in Humans
Authors: Conner Christopher R. , Ellmore Timothy M. , Pieters Thomas A. , DiSano Michael A. , Tandon Nitin
Published: September 2011

The relationship between blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal and the underlying neural electrical activity in humans is a topic of intense interest to systems neuroscience. This relationship has generally been assumed to be invariant regardless of the brain region and the cognitive task being studied. We critically evaluated these assumptions by comparing the BOLD-fMRI response with local field potential (LFP) measurements during visually cued common noun and verb generation in 11 humans in whom 1210 subdural electrodes were implanted. As expected, power in the mid-gamma band (60–120 Hz) correlated positively (r2= 0.16,p< 10−16) and power in the beta band (13–30 Hz) correlated negatively (r2= 0.09,p< 10−16) with the BOLD signal change. Beta and mid-gamma band activity independently explain different components of the observed BOLD signal. Importantly, we found that the location (i.e., lobe) of the recording site modulates the relationship between the electrocorticographic (ECoG) signal and the observed fMRI response (p< 10−16,F21,1830= 52.7), while the type of language task does not. Across all brain regions, ECoG activity in the gamma and beta bands explains 22% of the fMRI response, but if the lobar location is considered, 28% of the variance can be explained. Further evaluation of this relationship at the level of individual gyri provides additional evidence of differences in the BOLD-LFP relationship by cortical locus. This spatial variability in the relationship between the fMRI signal and neural activity carries implications for modeling of the hemodynamic response function, an essential step for interregional fMRI comparisons.
Spinal 5-HT3Receptor Activation Induces Behavioral Hypersensitivity via a Neuronal-Glial-Neuronal Signaling Cascade
Authors: Gu Ming , Miyoshi Kan , Dubner Ronald , Guo Wei , Zou Shiping , Ren Ke , Noguchi Koichi , Wei Feng
Published: September 2011

Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT3receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT3receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT3receptor by intrathecal injection of a selective 5-HT3receptor agonist, SR57227, induced spinal glial hyperactivity, neuronal hyperexcitability, and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via the cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous brain-derived neurotrophic factor-induced descending pain facilitation was accompanied by upregulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, and these events were significantly prevented by functional blockade of spinal 5-HT3receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia.
Selective Hippocampal Neurodegeneration in Transgenic Mice Expressing Small Amounts of Truncated Aβ Is Induced by Pyroglutamate–Aβ Formation
Authors: Alexandru Anca , Jagla Wolfgang , Graubner Sigrid , Becker Andreas , Bäuscher Christoph , Kohlmann Stephanie , Sedlmeier Reinhard , Raber Kerstin A. , Cynis Holger , Rönicke Raik , Reymann Klaus G. , Petrasch-Parwez Elisabeth , Hartlage-Rübsamen Maike , Waniek Alexander , Rossner Steffen , Schilling Stephan , Osmand Alexander P. , Demuth Hans-Ulrich , von Hörsten Stephan
Published: September 2011

Posttranslational amyloid-β (Aβ) modification is considered to play an important role in Alzheimer's disease (AD) etiology. An N-terminally modified Aβ species, pyroglutamate-amyloid-β (pE3–Aβ), has been described as a major constituent of Aβ deposits specific to human AD but absent in normal aging. Formed via cyclization of truncated Aβ species by glutaminyl cyclase (QC;QPCT) and/or its isoenzyme (isoQC;QPCTL), pE3–Aβ aggregates rapidly and is known to seed additional Aβ aggregation. To directly investigate pE3–Aβ toxicityin vivo, we generated and characterized transgenic TBA2.1 and TBA2.2 mice, which express truncated mutant human Aβ. Along with a rapidly developing behavioral phenotype, these mice showed progressively accumulating Aβ and pE3–Aβ deposits in brain regions of neuronal loss, impaired long-term potentiation, microglial activation, and astrocytosis. Illustrating a threshold for pE3–Aβ neurotoxicity, this phenotype was not found in heterozygous animals but in homozygous TBA2.1 or double-heterozygous TBA2.1/2.2 animals only. A significant amount of pE3–Aβ formation was shown to be QC-dependent, because crossbreeding of TBA2.1 with QC knock-out, but not isoQC knock-out, mice significantly reduced pE3–Aβ levels. Hence, lowering the rate of QC-dependent posttranslational pE3–Aβ formation can, in turn, lower the amount of neurotoxic Aβ species in AD.
Acquisition of Neural Learning in Cerebellum and Cerebral Cortex for Smooth Pursuit Eye Movements
Authors: Li Jennifer X. , Medina Javier F. , Frank Loren M. , Lisberger Stephen G.
Published: September 2011

We evaluated the emergence of neural learning in the frontal eye fields (FEFSEM) and the floccular complex of the cerebellum while monkeys learned a precisely timed change in the direction of pursuit eye movement. For each neuron, we measured the time course of changes in neural response across a learning session that comprised at least 100 repetitions of an instructive change in target direction. In both areas, the average population learning curves tracked the behavioral changes with high fidelity, consistent with possible roles in driving learning. However, the learning curves of individual neurons sometimes bore little relation to the smooth, monotonic progression of behavioral learning. In the FEFSEM, neural learning was episodic. For individual neurons, learning appeared at different times during the learning session and sometimes disappeared by the end of the session. Different FEFSEMneurons expressed maximal learning at different times relative to the acquisition of behavioral learning. In the floccular complex, many Purkinje cells acquired learned simple-spike responses according to the same time course as behavioral learning and retained their learned responses throughout the learning session. A minority of Purkinje cells acquired learned responses late in the learning session, after behavioral learning had reached an asymptote. We conclude that learning in single neurons can follow a very different time course from behavioral learning. Both the FEFSEMand the floccular complex contain representations of multiple temporal components of learning, with different neurons contributing to learning at different times during the acquisition of a learned movement.
Depth-Dependent Temporal Response Properties in Core Auditory Cortex
Authors: Christianson G. Björn , Sahani Maneesh , Linden Jennifer F.
Published: September 2011

The computational role of cortical layers within auditory cortex has proven difficult to establish. One hypothesis is that interlaminar cortical processing might be dedicated to analyzing temporal properties of sounds; if so, then there should be systematic depth-dependent changes in cortical sensitivity to the temporal context in which a stimulus occurs. We recorded neural responses simultaneously across cortical depth in primary auditory cortex and anterior auditory field of CBA/Ca mice, and found systematic depth dependencies in responses to second-and-later noise bursts in slow (1–10 bursts/s) trains of noise bursts. At all depths, responses to noise bursts within a train usually decreased with increasing train rate; however, the rolloff with increasing train rate occurred at faster rates in more superficial layers. Moreover, in some recordings from mid-to-superficial layers, responses to noise bursts within a 3–4 bursts/s train were stronger than responses to noise bursts in slower trains. This non-monotonicity with train rate was especially pronounced in more superficial layers of the anterior auditory field, where responses to noise bursts within the context of a slow train were sometimes even stronger than responses to the noise burst at train onset. These findings may reflect depth dependence in suppression and recovery of cortical activity following a stimulus, which we suggest could arise from laminar differences in synaptic depression at feedforward and recurrent synapses.
Group II/III Metabotropic Glutamate Receptors Exert Endogenous Activity-Dependent Modulation of TRPV1 Receptors on Peripheral Nociceptors
Authors: Carlton Susan M. , Zhou Shengtai , Govea Rosann , Du Junhui
Published: September 2011

There is pharmacological evidence that group II and III metabotropic glutamate receptors (mGluRs) function as activity-dependent autoreceptors, inhibiting transmission in supraspinal sites. These receptors are expressed by peripheral nociceptors. We investigated whether mGluRs function as activity-dependent autoreceptors inhibiting pain transmission to the rat CNS, particularly transient receptor potential vanilloid 1 (TRPV1)-induced activity. Blocking peripheral mGluR activity by intraplantar injection of antagonists LY341495 [(2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid] (LY) (20, 100 μm, group II/III), APICA [(RS)-1-amino-5-phosphonoindan-1-carboxylic acid] (100 μm, group II), or UBP1112 (α-methyl-3-methyl-4-phosphonophenylglycine) (30 μm, group III) increased capsaicin (CAP)-induced nociceptive behaviors and nociceptor activity. In contrast, group II agonist APDC [(2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate] (0.1 μm) or group III agonistl-(+)-2-amino-4-phosphonobutyric acid (l-AP-4) (10 μm) blocked the LY-induced increase. Ca2+imaging in dorsal root ganglion (DRG) cells confirmed LY enhanced CAP-induced Ca2+mobilization, which was blocked by APDC andl-AP-4. We hypothesized that excess glutamate (GLU) released by high intensity and/or prolonged stimulation endogenously activated group II/III, dampening nociceptor activation. In support of this, intraplantar GLU + LY produced heat hyperalgesia, and exogenous GLU + LY applied to nociceptors produced enhanced nociceptor activity and thermal sensitization. Intraplantar Formalin, known to elevate extracellular GLU, enhanced pain behaviors in the presence of LY. LY alone produced no pain behaviors, no change in nociceptor discharge rate or heat-evoked responses, and no change in cytosolic Ca2+in DRG cells, demonstrating a lack of tonic inhibitory control. Group II/III mGluRs maintain an activity-dependent autoinhibition, capable of significantly reducing TRPV1-induced activity. They are endogenously activated after high-frequency and/or prolonged nociceptor stimulation, acting as built-in negative modulators of TRPV1 and nociceptor function, reducing pain transmission to the CNS.
GENETICS IN ENDOCRINOLOGY: The genetics of phaeochromocytoma: using clinical features to guide genetic testing
Authors: Jafri Mariam , Maher Eamonn R
Published: September 2011

Phaeochromocytoma is a rare, usually benign, tumour predominantly managed by endocrinologists. Over the last decade, major advances have been made in understanding the molecular genetic basis of adrenal and extra-adrenal phaeochromocytoma (also referred to as adrenal phaeochromocytoma (aPCA) and extra-adrenal functional paraganglioma (eFPGL)). In contrast to the previously held belief that only 10% of cases had a genetic component, currently about one-third of all aPCA/eFPGL cases are thought to be attributable to germline mutations in at least nine genes (NF1, RET, SDHA, SDHB, SDHC, SDHD, TMEM127, MAX and VHL). Recognition of inherited cases of aPCA/eFPGL is critical for optimal patient management. Thus, the identification of a germline mutation can predict risks of malignancy, recurrent disease, associated non-chromaffin tumours and risks to other family members. Mutation carriers should be offered specific surveillance programmes (according to the relevant gene). In this review, we will describe the genetics of aPCA/eFPGL and strategies for genetic testing.
Diaphragmatic hernia or hiatus hernia: a diagnostic problem in 5-month-old infant
Authors: Józsa Gergő , Juhász Zsolt , Vajda Péter , Mohay Gabriella , Pintér András
Published: September 2011

Authors present a case of a 5-month-old infant, in whom following an uneventful perinatal adaptation, symptoms of recurrent respiratory infections, vomiting and growth failure developed. Based on chest X-ray, right-sided diaphragmatic hernia was suspected. However, barium swallow examination delineated the stomach above the right diaphragm. The case report draws attention to the differential diagnostic difficulties between congenital diaphragmatic and hiatal hernia. Orv. Hetil., 2011, 152, 1500–1503.
Ecological incumbency impedes stochastic community assembly in Holocene foraminifera from the Huon Peninsula, Papua New Guinea
Authors: Reymond Claire E. , Bode Michael , Renema Willem , Pandolfi John M.
Published: September 2011

Persistence in the structure of ecological communities can be predicted both by deterministic and by stochastic theory. Evaluating ecological patterns against the neutral theory of biodiversity provides an appropriate methodology for differentiating between these alternatives. We traced the history of benthic foraminiferal communities from the Huon Peninsula, Papua New Guinea. From the well-preserved uplifted reef terrace at Bonah River we reconstructed the benthic foraminiferal communities during a 2200-year period (9000–6800 yr B.P.) of reef building during the Holocene transgressive sea-level rise. We found that the similarity of foraminiferal communities was consistently above 60%, even when comparing communities on either side of a massive volcanic eruption that smothered the existing reef system with ash. Similarly, species diversity and rank dominance were unchanged through time. However, similarity dropped dramatically in the final stages of reef growth, when accommodation space was reduced as sea-level rise slowed. We compared the community inertia index (CII) computed from the observed species abundances with that predicted from neutral theory. Despite the differences in foraminiferal community composition in the younger part of the reef sequence, we found an overall greater degree of community inertia with less variance in observed communities than was predicted from neutral theory, regardless of foraminiferal community size or species migration rate. Thus, persistent species assemblages could not be ascribed to neutral predictions. Ecological incumbency of established foraminiferal species likely prevented stochastic increases in both migrant and rare taxa at the Bonah River site. Regardless of the structuring mechanisms, our reconstruction of Holocene foraminiferal assemblages provides historical context for the management and potential restoration of degraded species assemblages.
Relation between anatomy and lifestyles in Recent and Early Cambrian chaetognaths
Authors: Casenove David , Goto Taichiro , Vannier Jean
Published: September 2011

The Burgess Shale-type Lagerstätten of the Early Cambrian Maotianshan Shale record an apparently sudden conquest of pelagic niches by ten phyla of metazoans. One of these phyla is Chaetognatha, a group of predatory marine worms. Given their role as major predators in modern planktonic ecosystems, the chaetognaths discovered in the Maotianshan Shale (Yunnan Province, South China) suggest that the pelagos at the time was already quite complex. Modern chaetognaths, however, can be divided into benthic and pelagic forms; the pelagic nature ofEognathacantha ercainellashould therefore be validated by strong morphological evidence.

Knowing that planktonic animals present morphological adaptations that increase their buoyancy, we studied the drag produced during the active phase of chaetognath locomotion for the modern formsParaspadella gotoi(benthic) andSagitta elegans(pelagic). By using a motion model developed by Jordan in 1992, we could calculate the resistive force produced by the undulatory movement of chaetognaths' bodies.

This mechanistic approach evaluates the effect of three motion parameters (relative speed, total length, and tail ratio) on the drag force produced during locomotion. Our results show that the increase of size contributes to higher drag while the shorter tail of the pelagic form balances this effect by reducing the wetted surface subject to friction. For chaetognaths, therefore, a bigger body (both in length and width) and a shorter tail indicate a pelagic lifestyle, a finding that can be applied to the study of the fossilEognathacantha ercainella. A discriminant analysis can confirm that the Early Cambrian chaetognath presents a pelagic morphology with similarities to modern bathypelagic and mesopelagic species.
Local and global abundance associated with extinction risk in late Paleozoic and early Mesozoic gastropods
Authors: Payne Jonathan L. , Truebe Sarah , Nützel Alexander , Chang Ellen T.
Published: September 2011

Ecological theory predicts an inverse association between population size and extinction risk, but most previous paleontological studies have failed to confirm this relationship. The reasons for this discrepancy between theory and observation remain poorly understood. In this study, we compiled a global database of gastropod occurrences and collection-level abundances spanning the Early Permian through Early Jurassic (Pliensbachian). Globally, the database contains 5469 occurrences of 496 genera and 2156 species from 839 localities. Within the database, 30 collections distributed across seven stages contain at least 75 specimens and ten genera—our minimum criteria for within-collection analysis of extinction selectivity. We use logistic regression analysis, based on global and local measures of population size and stage-level extinction patterns in Early Permian through Early Jurassic marine gastropods, to assess the relationship between abundance and extinction risk. We find that global genus occurrence frequency is inversely associated with extinction risk (i.e., positively associated with survival) in 15 of 16 stages examined, statistically significantly so in five stages. Although correlation between geographic range and occurrence frequency may account for some of this association, results from multivariable regression analysis suggest that the association between occurrence frequency and extinction risk is largely independent of geographic range. Within local assemblages, abundance (number of individuals) is also inversely associated with extinction risk. The strength of association is consistent across time and modes of fossil preservation. Effect strength is poorly constrained, particularly in analyses of local collections. In addition to limited power due to small sample size, this poor constraint may result from confounding by ecological variables not controlled for in the analyses, by taphonomic or collection biases, or from non-monotonic relationships between abundance and extinction risk. Two factors are likely to account for the difference between our results and those of most previous studies. First, many previous studies focused on the end-Cretaceous mass extinction event; the extent to which these results can be generalized to other intervals remains unclear. Second, previous findings of nonselective extinction could result from insufficient statistical power rather than the absence of an underlying effect, because nonselective extinction is generally used as the null hypothesis for statistical convenience. Survivorship patterns in late Paleozoic and early Mesozoic gastropods suggest that abundance has been a more important influence on extinction risk through the Phanerozoic than previously appreciated.
Target reliability-based optimisation for internal seismic stability of reinforced soil structures
Authors: BASHA B.M. , BABU G.L.S.
Published: September 2011

In this paper, an approach for target component and system reliability-based design optimisation (RBDO) to evaluate safety for the internal seismic stability of geosynthetic-reinforced soil (GRS) structures is presented. Three modes of failure are considered: tension failure of the bottom-most layer of reinforcement, pullout failure of the topmost layer of reinforcement, and total pullout failure of all reinforcement layers. The analysis is performed by treating backfill properties, geometric and strength properties of reinforcement as random variables. The optimum number of reinforcement layers and optimum pullout length needed to maintain stability against tension failure, pullout failure and total pullout failure for different coefficients of variation of friction angle of the backfill, design strength of the reinforcement and horizontal seismic acceleration coefficients by targeting various system reliability indices are proposed. The results provide guidelines for the total length of reinforcement required, considering the variability of backfill as well as seismic coefficients. One illustrative example is presented to explain the evaluation of reliability for internal stability of reinforced soil structures using the proposed approach. In the second illustration (the stability of five walls), the Kushiro wall subjected to the Kushiro-Oki earthquake, the Seiken wall subjected to the Chiba-ken Toho-Oki earthquake, the Ta Kung wall subjected to the Ji-Ji earthquake, and the Gould and Valencia walls subjected to Northridge earthquake are re-examined.
The role of chitin in the decomposition of ectomycorrhizal fungal litter
Authors: Fernandez Christopher W. , Koide Roger T.
Published: September 2011

Ectomycorrhizal fungal tissues comprise a significant forest‐litter pool. Ectomycorrhizal (EM) fungi may also influence the decomposition of other forest‐litter components via competitive interactions with decomposer fungi and by ensheathing fine roots. Because of these direct and indirect effects of ectomycorrhizal fungi, the factors that control the decomposition of EM fungi will strongly control forest‐litter decomposition as a whole and, thus, ecosystem nutrient and carbon cycling. Some have suggested that chitin, a component of fungal cell walls, reduces fungal tissue decomposition because it is relatively recalcitrant. We therefore examined the change in chitin concentrations of EM fungal tissues during decomposition. Our results show that chitin is not recalcitrant relative to other compounds in fungal tissues and that its concentration is positively related to the decomposition of fungal tissues. Variation existing among EM fungal isolates in chitin concentration suggests that EM fungal community structure influences C and nutrient cycling.
A Note on a Double Temperature-Cascade Control Strategy for Distillation Columns
Authors: Urrea-Garcìa Galo R , Alvarez-Ramirez Jose , Luna-Solano Guadalupe , Bolaños-Reynoso Eusebio
Published: September 2011

A double temperature-cascade control strategy for controlling distillate composition is proposed. The control structure is based on two secondary loops that are designed for tracking the temperature of one tray in the rectifying and stripping section by manipulation of the reflux rate and reboiler heat input, respectively. Simulation results show that when saturations are imposed on controller outputs (reflux rate and heat input) both cascade controllers can act in a switching-like scheme without interaction problems. It is also shown that an adequate setting of a saturation parameter allows a low energy regulation of distillate composition under disturbances in feed composition.
Influence of monomer and crosslinker molar ratio on the swelling behaviour of thermosensitive hydrogels
Authors: Ilic-Stojanovic Snezana , Nikolic Ljubisa , Nikolic Vesna , Stankovic Mihajlo , Stamenkovic Jakov , Mladenovic-Ranisavljevic Ivana , Petrovic Slobodan
Published: September 2011

The synthesis of the
poly(N-isopropylacrylamide-co-2-hydroxypropylmethacrylate) hydrogel along
with the analysis of the residual monomers content and influence of monomer
and crosslinker molar ratios on the swelling behaviour was investigated.
Synthesis of thermosensitive hydrogel based on N-isopropylacrylamide was
carried out with the molar ratios of 5, 10, 15 and 20 mol. % of monomer 2-
hydroxypropyl-methacrylate, in the presence of ethylene glycol dimethacrylate
as a crosslinker (1, 1.5, 2 and 3 mol. %) and
2,2'-azobis(2-methylpropionitril) as an initiator in acetone. The quantities
of residual monomers in the synthesized copolymers were determined by HPLC
method, ranging from 0.19 to 0.49 % for N-isopropylacrylamide and from 0.13
to 0.63 % for 2-hydroxypropyl-methacrylate, counting the amount of xerogel.
The hydrogels swelling ratio depending on time at 20 and 40?C was examined.
It was found that hydrogel with 5 mol. % 2-hydroxypropyl-methacrylate and 1
mol. % ethylene glycol dimethacrylate had the highest degree of swelling (? =
29.59) at 20?C, and that hydrogel with 20 mol. % 2-hydroxypropyl-methacrylate
and 3 mol. % ethylene glycol dimethacrylate had the lowest swelling degree (?
= 2.17) at 40?C.
Mediobasal Hypothalamic SIRT1 Is Essential for Resveratrol’s Effects on Insulin Action in Rats
Authors: Knight Colette M. , Gutierrez-Juarez Roger , Lam Tony K.T. , Arrieta-Cruz Isabel , Huang Loli , Schwartz Gary , Barzilai Nir , Rossetti Luciano
Published: September 2011

OBJECTIVE

Sirtuin 1 (SIRT1) and its activator resveratrol are emerging as major regulators of metabolic processes. We investigate the site of resveratrol action on glucose metabolism and the contribution of SIRT1 to these effects. Because the arcuate nucleus in the mediobasal hypothalamus (MBH) plays a pivotal role in integrating peripheral metabolic responses to nutrients and hormones, we examined whether the actions of resveratrol are mediated at the MBH.

RESEARCH DESIGN AND METHODS

Sprague Dawley (SD) male rats received acute central (MBH) or systemic injections of vehicle, resveratrol, or SIRT1 inhibitor during basal pancreatic insulin clamp studies. To delineate the pathway(s) by which MBH resveratrol modulates hepatic glucose production, we silenced hypothalamic SIRT1 expression using a short hairpin RNA (shRNA) inhibited the hypothalamic ATP-sensitive potassium (KATP) channel with glibenclamide, or selectively transected the hepatic branch of the vagus nerve while infusing resveratrol centrally.

RESULTS

Our studies show that marked improvement in insulin sensitivity can be elicited by acute administration of resveratrol to the MBH or during acute systemic administration. Selective inhibition of hypothalamic SIRT1 using a cell-permeable SIRT1 inhibitor or SIRT1-shRNA negated the effect of central and peripheral resveratrol on glucose production. Blockade of the KATP channel and hepatic vagotomy significantly attenuated the effect of central resveratrol on hepatic glucose production. In addition, we found no evidence for hypothalamic AMPK activation after MBH resveratrol administration.

CONCLUSIONS

Taken together, these studies demonstrate that resveratrol improves glucose homeostasis mainly through a central SIRT1-dependent pathway and that the MBH is a major site of resveratrol action.