bluuebunny/crossref_metadata_2025 huggingface dataset:
The Applicability of Numerical Models to Adequately Characterize Ground-Water Flow in Karstic and Other Triple-Porosity Aquifers
Authors: Quinlan JF , Davies GJ , Jones SW , Huntoon PW
Published: March 2009

Numerical models of ground-water flow have met with limited success when applied to aquifers in soluble rocks, commonly referred to as karstic aquifers. Although modeling of karstic processes is often possible and numerical flow models can sometimes simulate hydraulic heads, ground-water fluxes, and spring discharge, they often fail to correctly predict such fundamental information as flow direction, destination, and velocity. The poor performance of numerical models in karstic aquifers has resulted from: 1) inappropriate emphasis on the local scale when flow paths are often orders of magnitude longer, 2) the large amount of hydrogeologic data required to model such anisotropic, heterogeneous aquifers and the additional data requirements necessary to establish realistic boundary conditions 3) the necessity to develop models which incorporate triple continuum concepts, 4) the difficulty of properly characterizing and modeling transient events in karst aquifers and, 5) the inadequacy of laminar flow equations or Darcy's law to describe the flow in conduits in the aquifer. Most numerical models of ground-water flow in karst aquifers nevertheless continue to employ single-continuum porous-medium models such as MODFLOW and are based on invalid interpolation of inappropriate data collected far too infrequently from points that did not intersect preferential flow paths. Unfortunately, some of these modeling attempts have been substituted for the collection of the additional data that are essential to providing adequate characterization of ground-water flow at sites underlain by karstic aquifers.
Regulation of Glucose Transporter 3 Surface Expression by the AMP-Activated Protein Kinase Mediates Tolerance to Glutamate Excitation in Neurons
Authors: Weisová Petronela , Concannon Caoimhín G. , Devocelle Marc , Prehn Jochen H. M. , Ward Manus W.
Published: March 2009

Ischemic and excitotoxic events within the brain result in rapid and often unfavorable depletions in neuronal energy levels. Here, we investigated the signaling pathways activated in response to the energetic stress created by transient glutamate excitation in cerebellar granule neurons. We characterized a glucose dependent hyperpolarization of the mitochondrial membrane potential (Δψm) in the majority of neurons after transient glutamate excitation. Expression levels of the primary neuronal glucose transporters (GLUTs) isoforms 1, 3, 4, and 8 were found to be unaltered within a 24 h period after excitation. However, a significant increase only in GLUT3 surface expression was identified 30 min after excitation, with this high surface expression remaining significantly above control levels in many neurons for up to 4 h. Glutamate excitation induced a rapid alteration in the AMP:ATP ratio that was associated with the activation of the AMP-activated protein kinase (AMPK). Interestingly, pharmacological activation of AMPK with AICAR (5-aminoimidazole-4-carboxamide riboside) alone also increased GLUT3 surface expression, with a hyperpolarization of Δψmevident in many neurons. Notably, inhibition of the CaMKK (calmodulin-dependent protein kinase kinase) had little affect on GLUT translocation, whereas the inhibition or knockdown of AMPK (compound C, siRNA) activity prevented GLUT3 translocation to the cell surface after glutamate excitation. Furthermore, gene silencing of GLUT3 eradicated the increase in Δψmassociated with transient glutamate excitation and potently sensitized neurons to excitotoxicity. In summary, our data suggest that the activation of AMPK and its regulation of cell surface GLUT3 expression is critical in mediating neuronal tolerance to excitotoxicity.
Identified Ankle Extensor and Flexor Motoneurons Display Different Firing Profiles in the Neonatal Rat
Authors: Cotel Florence , Antri Myriam , Barthe Jean-Yves , Orsal Didier
Published: March 2009

The present study was designed to compare the firing profiles exhibited by lumbar flexor or extensor motoneurons in response to injection of depolarizing/repolarizing currents. Motoneurons were recorded intracellularly in thein vitrobrainstem-spinal cord of newborn rats (P4–P7). They were synaptically isolated and identified by antidromic stimulations of the central stump of flexor or extensor muscle nerves: tibialis anterior (ankle flexor) and gastrocnemius medialis or lateralis (ankle extensors). Two protocols were applied to establish the four firing profiles previously described (type I–IV) (Bennett et al., 2001): (1) symmetric depolarizing/repolarizing ramps of current and (2) progressive steps of depolarizing currents followed by equivalent steps of repolarizing current. According to such profiles, this study clearly shows that flexor and extensor motoneurons are different. The whole population of flexor motoneurons solely exhibited the type II profile, characterized by a frequency–current (F–I) relationship with a clockwise hysteresis. In contrast, in addition to this type II profile, the other three profiles of repetitive firing (type I, III and IV) were observed in extensor motoneurons; a linearF–Irelationship (type I profile), a self-sustained discharge pattern together with a linearF–Irelationship (type III profile) and a self-sustained firing pattern together with anF–Irelationship showing a counter-clockwise hysteresis (type IV profile). Thus, during the early postnatal development, a significant part of the population of extensor motoneurons, but not flexors, are able to produce self-sustained discharges known to involve the activation of persistent inward currents.
DSCAM Deficiency Causes Loss of Pre-Inspiratory Neuron Synchroneity and Perinatal Death
Authors: Amano Kenji , Fujii Morimitsu , Arata Satoru , Tojima Takuro , Ogawa Masaharu , Morita Noriyuki , Shimohata Atsushi , Furuichi Teiichi , Itohara Shigeyoshi , Kamiguchi Hiroyuki , Korenberg Julie R. , Arata Akiko , Yamakawa Kazuhiro
Published: March 2009

Down syndrome cell adhesion molecule (DSCAM) is a neural adhesion molecule that plays diverse roles in neural development. We disrupted theDscamlocus in mice and found that the null mutants (Dscam−/−) died within 24 h after birth. Whole-body plethysmography showed irregular respiration and lower ventilatory response to hypercapnia in the null mutants. Furthermore, a medulla–spinal cord preparation ofDscam−/−mice showed that the C4 ventral root activity, which drives diaphragm contraction for inspiration, had an irregular rhythm with frequent apneas. Optical imaging of the preparation using voltage-sensitive dye revealed that the pre-inspiratory neurons located in the rostral ventrolateral medulla and belonging to the rhythm generator for respiration, lost their synchroneity inDscam−/−mice.Dscam+/−mice, which survived to adulthood without any overt abnormalities, also showed irregular respiration but milder thanDscam−/−mice. These results suggest that DSCAM plays a critical role in central respiratory regulation in a dosage-dependent manner.
Mg2+Imparts NMDA Receptor Subtype Selectivity to the Alzheimer's Drug Memantine
Authors: Kotermanski Shawn E. , Johnson Jon W.
Published: March 2009

N-Methyl-d-aspartate receptors (NMDARs) mediate interneuronal communication and are broadly involved in nervous system physiology and pathology (Dingledine et al., 1999). Memantine, a drug that blocks the ion channel formed by NMDARs, is a widely prescribed treatment of Alzheimer's disease (Schmitt, 2005; Lipton, 2006; Parsons et al., 2007). Research on memantine's mechanism of action has focused on the NMDAR subtypes most highly expressed in adult cerebral cortex, NR1/2A and NR1/2B receptors (Cull-Candy and Leszkiewicz, 2004), and has largely ignored interactions with extracellular Mg2+(Mg2+o). Mg2+ois an endogenous NMDAR channel blocker that binds near memantine's binding site (Kashiwagi et al., 2002; Chen and Lipton, 2005). We report that a physiological concentration (1 mm) of Mg2+odecreased memantine inhibition of NR1/2A and NR1/2B receptors nearly 20-fold at a membrane voltage near rest. In contrast, memantine inhibition of the other principal NMDAR subtypes, NR1/2C and NR1/2D receptors, was decreased only ∼3-fold. As a result, therapeutic memantine concentrations should have negligible effects on NR1/2A or NR1/2B receptor activity but pronounced effects on NR1/2C and NR1/2D receptors. Quantitative modeling showed that the voltage dependence of memantine inhibition also is altered by 1 mmMg2+o. We report similar results with the NMDAR channel blocker ketamine, a drug used to model schizophrenia (Krystal et al., 2003). These results suggest that currently hypothesized mechanisms of memantine and ketamine action should be reconsidered and that NR1/2C and/or NR1/2D receptors play a more important role in cortical physiology and pathology than previously appreciated.
p27KIP1Regulates Neurogenesis in the Rostral Migratory Stream and Olfactory Bulb of the Postnatal Mouse
Authors: Li Xuekun , Tang Xiaobing , Jablonska Beata , Aguirre Adan , Gallo Vittorio , Luskin Marla B.
Published: March 2009

Neuronal progenitor cells of the anterior subventricular zone (SVZa) migrate along the rostral migratory stream (RMS) to the olfactory bulb, where they exit the cell cycle and differentiate. The molecular mechanisms that regulate SVZa progenitor proliferation and cell-cycle exit are largely undefined. We investigated the role of p27KIP1in regulating cell proliferation and survival in the RMS and olfactory bulb between postnatal day 1 (P1) and P14, the peak period of olfactory bulb neuron generation. A large proportion of cells in the RMS and the olfactory bulb express cytoplasmic p27KIP1, but a small percentage display high nuclear p27KIP1immunostaining, which exhibit a caudallow–rostralhighgradient: lowest in the SVZa and highest in the glomerular layer of the olfactory bulb. p27KIP1is also present in the nucleus and/or the cytoplasm of neuron-specific type III β-tubulin(+) cells. Cells with strong nuclear p27KIP1expression are BrdU(−) and Ki67(−). The percentage of BrdU(+) cells in the SVZa, RMS, and olfactory bulb is higher in p27KIP1null than wild-type (WT) mice at all ages analyzed. Consistent with these findings, p27KIP1overexpression in cultured p27KIP1null and WT SVZ cells reduced cell proliferation and self-renewal. Finally, in p27KIP1null mice, the diameter of the horizontal limb of the RMS is larger than in WT mice, and development of the olfactory bulb granule cell layer is delayed, together with increased apoptotic cell density. Our results indicate that in the postnatal brain, p27KIP1regulates the proliferation and survival of neuronal cells in the RMS and olfactory bulb.
Differential Corticosteroid Modulation of Inhibitory Synaptic Currents in the Dorsal and Ventral Hippocampus
Authors: Maggio Nicola , Segal Menahem
Published: March 2009

Corticosterone has been known to mediate the effects of stress on cognitive functions associated with the hippocampus. Acting at mineralocorticosteroid receptors (MRs) and glucocorticosteroid receptors (GRs), corticosterone exerts several effects in the hippocampus and elsewhere. Assuming that there are major functional differences between the dorsal hippocampus (DH) and ventral hippocampus (VH), and that these may be regulated by local interneurons, we analyzed the action of corticosterone on inhibitory synaptic currents in patch-clamped pyramidal neurons, recorded in acute slices of DH and VH. Corticosterone, through activation of MRs, reduced the frequency of spontaneous IPSCs in VH but not in DH neurons, and markedly suppressed paired-pulse facilitation of evoked inhibitory synaptic currents. These effects were mimicked by aldosterone, an MR agonist, and were blocked by an MR antagonist. In contrast, corticosterone caused an increase in the magnitude of IPSCs in both the DH and VH via its activation of GRs. This effect was mimicked by a GR agonist, dexamethasone, which produced a slow-onset, large potentiation reaching a peak within 45–60 min after onset of perfusion, and was blocked by a GR antagonist. The amplitude of mIPSCs was markedly increased by the GR agonist, indicating a synaptic locus of effect. These results indicate that corticosterone has a dual action, which may underlie the differential functional effects of stress hormones in the DH and VH.
Exercise Reduces GABA Synaptic Input onto Nucleus Tractus Solitarii Baroreceptor Second-Order Neurons via NK1 Receptor Internalization in Spontaneously Hypertensive Rats
Authors: Chen Chao-Yin , Bechtold Andrea G. , Tabor Jocelyn , Bonham Ann C.
Published: March 2009

A single bout of mild to moderate exercise can lead to a postexercise decrease in blood pressure in hypertensive subjects, namely postexercise hypotension (PEH). The full expression of PEH requires a functioning baroreflex, hypertension, and activation of muscle afferents (exercise), suggesting that interactions in the neural networks regulating exercise and blood pressure result in this fall in blood pressure. The nucleus tractus solitarii (NTS) is the first brain site that receives inputs from nerves carrying blood pressure and muscle activity information, making it an ideal site for integrating cardiovascular responses to exercise. During exercise, muscle afferents excite NTS GABA neurons via substance P and microinjection of a substance P–neurokinin 1 receptor (NK1-R) antagonist into the NTS attenuates PEH. The data suggest that an interaction between the substance P NK1-R and GABAergic transmission in the NTS may contribute to PEH. We performed voltage clamping on NTS baroreceptor second-order neurons in spontaneously hypertensive rats (SHRs). All animals were killed within 30 min and the patch-clamp recordings were performed 2–8 h after the sham/exercise protocol. The data showed that a single bout of exercise reduces (1) the frequency but not the amplitude of GABA spontaneous IPSCs (sIPSCs), (2) endogenous substance P influence on sIPSC frequency, and (3) sIPSC frequency response to exogenous application of substance P. Furthermore, immunofluorescence labeling in NTS show an increased substance P NK1-R internalization on GABA neurons. The data suggest that exercise-induced NK1-R internalization results in a reduced intrinsic inhibitory input to the neurons in the baroreflex pathway.
Activity of Neurochemically Heterogeneous Dopaminergic Neurons in the Substantia Nigra during Spontaneous and Driven Changes in Brain State
Authors: Brown Matthew T. C. , Henny Pablo , Bolam J. Paul , Magill Peter J.
Published: March 2009

Dopaminergic neurons of the substantia nigra (SN) and ventral tegmental area (VTA) are collectively implicated in motor- and reward-related behaviors. However, dopaminergic SN and VTA neurons differ on several functional levels, and dopaminergic SN neurons themselves vary in their intrinsic electrical properties, neurochemical characteristics and connections. This heterogeneity is not only important for normal function; calbindin (CB) expression by some dopaminergic SN neurons has been linked with their increased survival in Parkinson's disease. To test whether the activity of CB-negative and CB-positive dopaminergic SN neurons differs during distinct spontaneous and driven brain states, we recorded single units in anesthetized rats before, during and after aversive somatosensory stimuli. Recorded neurons were juxtacellularly labeled, confirmed to be dopaminergic, and tested for CB immunoreactivity. During cortical slow-wave activity, the firing of most dopaminergic neurons was slow and regular/irregular and unrelated to cortical slow oscillations. During spontaneous cortical activation, dopaminergic SN neurons fired in a more regular manner, with fewer bursts, but did not change their firing rate. Regardless of brain state, CB-negative dopaminergic neurons fired significantly faster than CB-positive dopaminergic neurons. This difference in firing rate was not mirrored by different firing patterns. Most CB-negative and CB-positive dopaminergic neurons did not respond to the aversive stimuli; of those that did respond, most were inhibited. We conclude that CB-negative and CB-positive dopaminergic neurons exhibit different activitiesin vivo. Furthermore, the firing of dopaminergic SN neurons is brain state-dependent, and, unlike dopaminergic VTA neurons, they are not commonly recruited or inhibited by aversive stimuli.
Control of the Postsynaptic Membrane Viscosity
Authors: Renner Marianne , Choquet Daniel , Triller Antoine
Published: March 2009

The physical properties of the postsynaptic membrane (PSM), including its viscosity, determine its capacity to regulate the net flux of synaptic membrane proteins such as neurotransmitter receptors. To address these properties, we studied the lateral diffusion of glycophosphatidylinositol-anchored green fluorescent protein and cholera toxin bound to the external leaflet of the plasma membrane. Relative to extrasynaptic regions, their mobility was reduced at synapses and even more at inhibitory than at excitatory ones. This indicates a higher density of obstacles and/or higher membrane viscosity at inhibitory contacts. Actin depolymerization reduced the confinement and accelerated a population of fast, mobile molecules. The compaction of obstacles thus depends on actin cytoskeleton integrity. Cholesterol depletion increased the mobility of the slow diffusing molecules, allowing them to diffuse more rapidly through the crowded PSM. Thus, the PSM has lipid-raft properties, and the density of obstacles to diffusion depends on filamentous actin. Therefore, lipid composition and actin-dependent protein compaction regulate viscosity of the PSM and, consequently, the molecular flow in and out of synapses.
Axial Diffusivity Is the Primary Correlate of Axonal Injury in the Experimental Autoimmune Encephalomyelitis Spinal Cord: A Quantitative Pixelwise Analysis
Authors: Budde Matthew D. , Xie Mingqiang , Cross Anne H. , Song Sheng-Kwei
Published: March 2009

The dissociation between magnetic resonance imaging (MRI) and permanent disability in multiple sclerosis (MS), termed the clinicoradiological paradox, can primarily be attributed to the lack of specificity of conventional, relaxivity-based MRI measurements in detecting axonal damage, the primary pathological correlate of long-term impairment in MS. Diffusion tensor imaging (DTI) has shown promise in specifically detecting axonal damage and demyelination in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). To quantify the specificity of DTI in detecting axonal injury,in vivoDTI maps from the spinal cords of mice with EAE and quantitative histological maps were both registered to a common space. A pixelwise correlation analysis between DTI parameters, histological metrics, and EAE scores revealed a significant correlation between the water diffusion parallel to the white matter fibers, or axial diffusivity, and EAE score. Furthermore, axial diffusivity was the primary correlate of quantitative staining for neurofilaments (SMI31), markers of axonal integrity. Both axial diffusivity and neurofilament staining were decreased throughout the entire white matter, not solely within the demyelinated lesions seen in EAE. In contrast, although anisotropy was significantly correlated with EAE score, it was not correlated with axonal damage. The results demonstrate a strong, quantitative relationship between axial diffusivity and axonal damage and show that anisotropy is not specific for axonal damage after inflammatory demyelination.
Synaptically Released Zinc Triggers Metabotropic Signaling via a Zinc-Sensing Receptor in the Hippocampus
Authors: Besser Limor , Chorin Ehud , Sekler Israel , Silverman William F. , Atkin Stan , Russell James T. , Hershfinkel Michal
Published: March 2009

Zn2+is coreleased with glutamate from mossy fiber terminals and can influence synaptic function. Here, we demonstrate that synaptically released Zn2+activates a selective postsynaptic Zn2+-sensing receptor (ZnR) in the CA3 region of the hippocampus. ZnR activation induced intracellular release of Ca2+, as well as phosphorylation of extracellular-regulated kinase and Ca2+/calmodulin kinase II. Blockade of synaptic transmission by tetrodotoxin or CdCl inhibited the ZnR-mediated Ca2+rises. The responses mediated by ZnR were largely attenuated by the extracellular Zn2+chelator, CaEDTA, and in slices from mice lacking vesicular Zn2+, suggesting that synaptically released Zn2+triggers the metabotropic activity. Knockdown of the expression of the orphan G-protein-coupled receptor 39 (GPR39) attenuated ZnR activity in a neuronal cell line. Importantly, we observed widespread GPR39 labeling in CA3 neurons, suggesting a role for this receptor in mediating ZnR signaling in the hippocampus. Our results describe a unique role for synaptic Zn2+acting as the physiological ligand of a metabotropic receptor and provide a novel pathway by which synaptic Zn2+can regulate neuronal function.
Identifying Heritable Brain Phenotypes in an Extended Pedigree of Vervet Monkeys
Authors: Fears Scott C. , Melega William P. , Service Susan K. , Lee Chris , Chen Kelly , Tu Zhuowen , Jorgensen Matthew J. , Fairbanks Lynn A. , Cantor Rita M. , Freimer Nelson B. , Woods Roger P.
Published: March 2009

The area and volume of brain structural features, as assessed by high-resolution three-dimensional magnetic resonance imaging (MRI), are among the most heritable measures relating to the human CNS. We have conducted MRI scanning of all available monkeys >2 years of age (n= 357) from the extended multigenerational pedigree of the Vervet Research Colony (VRC). Using a combination of automated and manual segmentation we have quantified several correlated but distinct brain structural phenotypes. The estimated heritabilities (h2) for these measures in the VRC are higher than those reported previously for such features in humans or in other nonhuman primates: total brain volume (h2= 0.99, SE = 0.06), cerebral volume (h2= 0.98, SE = 0.06), cerebellar volume (h2= 0.86, SE = 0.09), hippocampal volume (h2= 0.95, SE = 0.07) and corpus callosum cross-sectional areas (h2= 0.87, SE = 0.07). These findings indicate that, in the controlled environment and with the inbreeding structure of the VRC, additive genetic factors account for almost all of the observed variance in brain structure, and suggest the potential of the VRC for genetic mapping of quantitative trait loci underlying such variance.
Roles of the Insular Cortex in the Modulation of Pain: Insights from Brain Lesions
Authors: Starr Christopher J. , Sawaki Lumy , Wittenberg George F. , Burdette Jonathan H. , Oshiro Yoshitetsu , Quevedo Alexandre S. , Coghill Robert C.
Published: March 2009

Subjective sensory experiences are constructed by the integration of afferent sensory information with information about the uniquely personal internal cognitive state. The insular cortex is anatomically positioned to serve as one potential interface between afferent processing mechanisms and more cognitively oriented modulatory systems. However, the role of the insular cortex in such modulatory processes remains poorly understood. Two individuals with extensive lesions to the insula were examined to better understand the contribution of this brain region to the generation of subjective sensory experiences. Despite substantial differences in the extent of the damage to the insular cortex, three findings were common to both individuals. First, both subjects had substantially higher pain intensity ratings of acute experimental noxious stimuli than age-matched control subjects. Second, when pain-related activation of the primary somatosensory cortex was examined during left- and right-sided stimulation, both individuals exhibited dramatically elevated activity of the primary somatosensory cortex ipsilateral to the lesioned insula in relation to healthy control subjects. Finally, both individuals retained the ability to evaluate pain despite substantial insular damage and no evidence of detectible insular activity. Together, these results indicate that the insula may be importantly involved in tuning cortical regions to appropriately use previous cognitive information during afferent processing. Finally, these data suggest that a subjectively available experience of pain can be instantiated by brain mechanisms that do not require the insular cortex.
Vasopressin 1b Receptor Knock-Out Impairs Memory for Temporal Order
Authors: DeVito Loren M. , Konigsberg Rachael , Lykken Christine , Sauvage Magdalena , Young W. Scott , Eichenbaum Howard
Published: March 2009

Mice lacking a functional vasopressin 1b receptor (Avpr1b) display decreased levels of aggression and social memory. Here, we used Avpr1b-knock-out (Avpr1b−/−) mice to examine whether an abnormality of this receptor results in specific cognitive deficits in the domain of hippocampal function. Avpr1b−/−mice were deficient in sociability and in detecting social novelty, extending previous findings of impairment in social recognition in these mutants. Avpr1b−/−mice could recognize previously explored objects and remember where they were experienced, but they were impaired in remembering the temporal order of presentation of those objects. Consistent with this finding, Avpr1b−/−mice were also impaired on an object–odor paired associate task that involved a temporal discontiguity between the associated elements. Finally, Avpr1b−/−mice performed normally in learning a set of overlapping odor discriminations and could infer relationships among odors that were only indirectly associated (i.e., transitive inference), indicating intact relational memory. The Avpr1b is expressed at much higher levels than any other part of the brain in the pyramidal cells of hippocampal CA2 area, a subfield of the hippocampus that has physiological and genetic properties that distinguish it from subfields CA1 and CA3. The combined results suggest that the Avpr1b, perhaps in CA2, may play a highly specific role in social behavior and episodic memory. Because schizophrenia and bipolar disorder are associated with a unique pathology in CA2 and impairments in both social behavior and episodic memory, this animal model could provide insights into the etiology of these disorders.
rhomboidMediates Specification of Blue- and Green-Sensitive R8 Photoreceptor Cells inDrosophila
Authors: Birkholz Denise A. , Chou Wen-Hai , Phistry Meridee M. , Britt Steven G.
Published: March 2009

Color vision is based on the differential color sensitivity of retinal photoreceptors, however the developmental programs that control photoreceptor cell differentiation and specify color sensitivity are poorly understood. InDrosophilathere is growing evidence that the color sensitivity of the R8 cell within an individual ommatidium is regulated by an inductive signal from the adjacent R7 cell. We previously examined the retinal patterning defect inScutoidmutants, which results from a disruption ofrhomboidexpression. Here we show that loss ofrhomboidblocks the induction of Rh5 expression and misexpression ofrhomboidleads to the inappropriate induction of Rh5. These effects are specific torhomboid, because its paralogueroughoidis neither required nor sufficient for the induction of Rh5 expression. We show thatrhomboidis required cell-autonomously within the R8 photoreceptor cells and nonautonomously elsewhere in the eye for Rh5 induction. Interestingly, we found that theEpidermal growth factor receptoris also required for Rh5 induction, and its activation is sufficient to rescue the loss of Rh5 induction in arhomboidmutant. This suggests thatrhomboidmay function in R8 cells to activateEpidermal growth factor receptorsignaling in R7 cells and promote their differentiation to a signaling competent state.
Histone Deacetylase Inhibitors Prevent p53-Dependent and p53-Independent Bax-Mediated Neuronal Apoptosis through Two Distinct Mechanisms
Authors: Uo Takuma , Veenstra Timothy D. , Morrison Richard S.
Published: March 2009

Pharmacological manipulation of protein acetylation levels by histone deacetylase (HDAC) inhibitors represents a novel therapeutic strategy to treat neurodegeneration as well as cancer. However, the molecular mechanisms that determine how HDAC inhibition exerts a protective effect in neurons as opposed to a cytotoxic action in tumor cells has not been elucidated. We addressed this issue in cultured postnatal mouse cortical neurons whose p53-dependent and p53-independent intrinsic apoptotic programs require the proapoptotic multidomain protein, Bax. Despite promoting nuclear p53 accumulation, Class I/II HDAC inhibitors (HDACIs) protected neurons from p53-dependent cell death induced by camptothecin, etoposide, heterologous p53 expression or the MDM2 inhibitor, nutlin-3a. HDACIs suppressed p53-dependent PUMA expression, a critical signaling intermediate linking p53 to Bax activation, thus preventing postmitochondrial events including cleavage of caspase-9 and caspase-3. In human SH-SY5Y neuroblastoma cells, however, HDACIs were not able to prevent p53-dependent cell death. Moreover, HDACIs also prevented caspase-3 cleavage in postnatal cortical neurons treated with staurosporine, 3-nitropropionic acid and a Bcl-2 inhibitor, all of which require the presence of Bax but not p53 to promote apoptosis. Although these three toxic agents displayed a requirement for Bax, they did not promote PUMA induction. These results demonstrate that HDACIs block Bax-dependent cell death by two distinct mechanisms to prevent neuronal apoptosis, thus identifying for the first time a defined molecular target for their neuroprotective actions.
Multilocus sequence typing for investigation of diversity of Campylobacter jejuni strains from humans and environment in Norway
Authors: Petkovic Jelena , Rudi Knut , Buncic Olivera , Katic Vera , Lepsanovic Zorica
Published: March 2009

This report describes the use of the Multilocus Sequence Typing (MLST) method for typing 32 strains previously identified as
Campylobacter jejuni
. This system identified a great diversity between the investigated strains. The majority of strains belonged to already existing alleles found on the
Campylobacter
MLST home page, and most of them represented clonal complexes ST-21 and ST-45, but there were some newly identified alleles as well.
Detection of trace amounts of abamectin used as an antiparasitic agent in fallow deer tissues
Authors: Žele Diana , Kobal Silvestra , Vengušt Gorazd , Bidovec Andrej , Vengušt Anton , Tavčar-Kalcher Gabrijela
Published: March 2009

A sensitive and reliable method for the determination of trace amounts of abamectin in muscles, kidneys and fat tissue of fallow deer is presented. Abamectin was extracted from the tissues with acetonitrile and the extract was cleaned up on a C8 solid-phase extraction cartridge. Abamectin residue was derivatised with trifluoroacetic acid anhydride and 1-methylimidazole, and determined using reversed- phase high-performance liquid chromatography under isocratic conditions and fluorescence detection. The recoveries of the method were high and consistent, ranging from 78% to 90%. The limit of detection of the method was below 1 μg/kg when analysing muscle, kidney and fat tissue. Matrix-matched calibration was used in order to obtain accurate values and to avoid matrix interference.
Single oral inoculation with Escherichia coli (ATCC 25922) stimulates generalised production of nitric oxide in mice
Authors: Nemec Ana , Pavlica Zlatko , Crossley David , Zdovc Irena , Eržen Damijan , Šentjurc Marjeta , Nemec Marjana , Petelin Milan
Published: March 2009

Nitric oxide (NO) production was investigated in the lungs, thoracic aorta, heart, liver, spleen, kidneys and brain of mice inoculated orally withEscherichia coliATCC 25922. Detection of NO was performed by electron paramagnetic resonance (EPR) using diethyldithiocarbamate (DETC) spin trap. Nitric oxide synthase (NOS) inhibitors [nonselective: L-NAME and inducible NOS (iNOS) selective: 1400W] were used to determine the source of NO. Spin-trap only and untreated mice were included as controls. Within 2.5 hours (h) of a single oral inoculation withE. colihalf of the animals had increased NO levels in all investigated organs. Thereafter the signals dropped before increasing again to reach maximal median values by 25 h in all organs of all inoculated mice. The most intense response occurred in livers, followed by aorta and lungs. Early (2.5 h) inhibition of the signal was achieved using both NOS inhibitors. L-NAME was also effective at 25 h, while 1400W-treated mice had increased NO levels beyond 7 h. The generalised increase in NO production in the short and longer term indicates a host response toE. coliadministered by the oral route of infection.
Glycogenic induction of thyroid hormone conversion and leptin system activation in the liver of postpartum dairy cows
Authors: Győrffy Andrea , Keresztes Mónika , Faigl Vera , Frenyó Vilmos , Kulcsár Margit , Gaál Tibor , Mézes Miklós , Zsarnovszky Attila , Huszenicza Gyula , Bartha Tibor
Published: March 2009

In the regulation of energy metabolism, the liver plays an important role in the reinforcement of energy production. In periparturient cows the energy homeostasis turns into a negative energy balance that may shift the physiological regulation of energy balance towards pathological processes. Propylene glycol (PG), as a complementary source of energy used in the nutrition of dairy cows, alters systemic thyroid hormone economy; however, the exact mechanism through which highly glycogenic feed supplements impact liver metabolism is little known. Previous studies showed that only leptin receptors are expressed in the liver of cows, and now we report that leptin mRNA is expressed in the liver of cows as well. The present results show that the mRNA of leptin and its receptors are differentially modulated by the increased energy content of the feed consumed. Simultaneous changes in hepatic type I deiodinase activity suggest that hepatic modulation of the leptin system by PG supplementation may be mediated by an increased local thyroxine-triiodothyronine conversion. Since PG supplementation with simultaneous T4–T3 turnover and increased hepatic leptin- and short-form leptin receptor mRNA were not associated with a significant change in hepatic total lipid levels, it is suggested that the leptin system, directly or indirectly modulated by thyroid hormones, may represent a local defence mechanism to prevent fatty liver formation.
Spaying-related urinary incontinence and oestrogen therapy in the bitch
Authors: Veronesi Maria , Rota Alessandro , Battocchio Massimiliano , Faustini Massimo , Mollo Antonio
Published: March 2009

Some aspects of spaying-related urinary incontinence in the bitch still remain incompletely clarified. Therefore, the aims of the present study were to evaluate the prevalence of the disease among spayed dogs, to detect differences in risk related to the type of surgery, to describe the characteristics of incontinent bitches, to assess the influence of age at surgery on the onset of incontinence occurrence, and to assess the effectiveness and long-term side effects of oestrogen therapy in affected bitches. Among 750 bitches submitted to ovariectomy or ovariohysterectomy, those showing spaying-related urinary incontinence were evaluated. Oestrogen replacement therapy consisted of administering an effective dose followed by an individual maintenance dose. The results showed that the disease occurred in 5% of neutered bitches, the type of surgery did not affect the disease occurrence, affected bitches frequently represented large or giant breeds or large-size mongrels, the body weight of the affected bitches at surgery was often ≥ 20 kg, the disease seems to be associated with tail docking, the age at surgery influences the onset of incontinence, with earlier occurrence in older bitches, and that a strong co-operation between owners and veterinarians is necessary to achieve successful response to oestrogen replacement therapy. Long-term administration seems to be unrelated to oestrogenic side effects.
A biological hazard of our age: Bracken fern [ Pteridium aquilinum (L.) Kuhn] — A Review
Authors: Vetter János
Published: March 2009

Bracken fern (Pteridium aquilinum) is the fifth most distributed common weed species of the world. Its ecological distribution is very wide, and the plant can grow and spread successfully on many types of soil. The cover ofP. aquilinumis — in some cases — remarkable (e.g. in the United Kingdom). Bracken fern contains different poisonous agents: some cyanogen glycosides, factors (agents) of antithiamine character (thermolabile thiaminase and thermostable other compounds) and factors of carcinogenic activity (first of all ptaquiloside). This paper summarises and reviews different toxicological problems and poisonings caused by bracken fern in ruminants (cattle, sheep) and in non-ruminant animals (horses, pigs, rats, mice, etc.). The carcinogenic properties of the norsesquiterpene-type ptaquiloside make bracken fern a potent, living hazard. Recent investigations have shown that ptaquiloside pollution of different soil layers is a distinct possibility. Ptaquiloside may leach from the soil into the drinking water base. This ecotoxicological aspect seems to be the most hazardous phenomenon in relation toP. aquilinumand ptaquiloside. The carcinogenic effect of ptaquiloside is based on its hydrolysis, which leads to the formation of a dienon intermediate. It can produce DNA adducts, which are responsible for inducing carcinoma.
Antimicrobial activity of Enterococcus faecium EF 55 against Salmonella Enteritidis in chicks
Authors: Levkut Mikuláš , Pistl Juraj , Lauková Andrea , Revajová Viera , Herich Robert , Ševčíková Zuzana , Strompfová Viola , Szabóová Renáta , Kokinčáková Tatiana
Published: March 2009

The protective effect ofEnterococcus faeciumEF 55 againstSalmonella entericaserovar Enteritidis phage type 4 (SE PT4) was studied in 1-day-old chicks. The EF 55 strain (isolated and characterised by the authors earlier) was applied daily (1.109CFU/0.2 ml PBS) for 7 days. Oral inoculation of the SE PT4 strain was performed on day 8 in a single dose of 5.108CFU/0.2 ml PBS. The experiment lasted for 21 days. Samples were collected on day 1 of the experiment to verify the absence ofSalmonella, on day 8 to check colonisation of EF 55 and immunological status in experimental birds, and on days 2, 4, 6, 8 and 14 after SE PT4 infection of chicks. Strain EF 55 sufficiently colonised the digestive tract of chicks after 7 days of application. The highest numbers of EF 55 in the faeces of chicks were observed before SE infection and persisted to day 6 post infection (p.i.) in both the EF and EF+SE groups. PCR confirmed the identity of the EF 55 strain. The counts of SE PT4 strain in faeces of the EF+SE group were significantly reduced in comparison to those in the SE group on days 2 and 14 p.i. (P < 0.01). The significant reduction of salmonellae in the caecum was recorded at the end of the experiment (day 14 p.i.) in the EF+SE group in comparison to the SE group (P < 0.01). At day 4 p.i., colonies ofS. Enteritidis PT4 were found in the liver of chicks of the SE group in a higher concentration than in chicks of the EF+SE group (P < 0.001). Salmonellae were isolated from the liver until days 8 and 6 p.i. in the SE and EF+SE groups, respectively. The mean values of actual lymphocyte subpopulations in the blood and the relative percentage of caecal intraepithelial lymphocyte subpopulations (CD4, CD8, CD44, TCR, MHC II and IgM) were not influenced at a statistically significant level by the application of the EF 55 and/or the SE PT4 strain. The results demonstrate the antimicrobial effect ofE. faeciumEF 55 againstS. Enteritidis PT4.
Frequency of genotypes in the PrP prion protein gene locus in the polish sheep population
Authors: Rejduch Barbara , Knapik Jan , Piestrzyńska-Kajtoch Agata , Kozubska-Sobocińska Anna , Krupiński Jędrzej
Published: March 2009

Scrapie is an invariably fatal transmissible neurodegenerative disease of sheep, goats and moufflons, characterised by ataxia, lower body weight and changes in behaviour. The aim of this study was to determine the genotype distribution at codons 136, 154 and 171 of thePrPlocus in sheep bred in Poland. The genotypes of 801 sheep representing 10 different breeds and crossbreds were analysed using real-time PCR allele discrimination method. The combination of point mutations of the three codons (136, 154 and 171) created twelve different genotypes in thePrPlocus classified into five categories of risk. The highest frequency for the ARR/ARR genotype was characteristic of the Pogórze and Berrichon du Cher breeds (72.22% and 63.25%, respectively). In the Romanov breed (1.52%) and in crossbred sheep (2.61%) the VRQ/VRQ genotype was observed.
Secondary tumoural valvulopathy in a dog
Authors: Jakab Csaba , Szász Attila , Kulka Janina , Baska Ferenc , Rusvai Miklós , Gálfi Péter , Németh Tibor
Published: March 2009

This short report describes a case of tricuspid valvular metastasis of canine disseminated histiocytic sarcoma in a 9-year-old female Rottweiler. Immunohistochemically the malignant neoplastic cells gave a strong reaction for vimentin and lysozyme, and showed negativity for serotonin, CD3, CD79a and cytokeratin. The intratumoural microvessels were detected by immunohistochemistry using CD31 and claudin-5. This appears to be the first report of a valvular metastasis of canine malignant histiocytosis.
Squamous cell carcinoma and consequent otitis in a long-eared hedgehog ( Hemiechinus auritus ) — Case report
Authors: Gál János , Landauer Krisztina , Palade Elena , Ivaskevics Katalin , Rusvai Miklós , Demeter Zoltán
Published: March 2009

The authors describe a squamous cell carcinoma arising from the ear canal of a Long-eared Hedgehog (
Hemiechinus auritus
). No metastasis could be identified elsewhere in the animal. Due to the irritation caused by the tumorous proliferation the animal constantly scratched the affected area, which led to secondary bacterial infection of the middle ear accompanied by the stagnation of an increased volume of local secretions. Using routine haematoxylin and eosin and immunohistochemical staining techniques, the tumour was identified as a squamous cell carcinoma. This work constitutes the first description of such a tumour in a Long-eared Hedgehog.
Effect of combined treatment with aflatoxin B 1 and T-2 toxin and metabolites on some production traits and lipid peroxide status parameters of broiler chickens
Authors: Pál László , Dublecz Károly , Weber Mária , Balogh Krisztián , Erdélyi Márta , Szigeti Gábor , Mézes Miklós
Published: March 2009

Three groups of cockerels were fed with a control diet, with a diet contaminated with T-2 and HT-2 toxin (0.31 and 0.26 mg/kg) or with that containing a combination of T-2 and HT-2 toxin (0.32 and 0.25 mg/kg) and aflatoxin B1(AFB1, 0.38 mg/kg) for 21 days. Body weight gain and feed conversion ratio did not differ significantly among the groups. Malondialdehyde concentration of the liver was lower in the group fed the diet contaminated with the combination of T-2 + HT-2 toxin and aflatoxin B1as compared to the control group or the group fed T-2 + HT-2 toxins. Reduced glutathione (GSH) content of the liver was lower in the T-2 + HT-2 group than in the group fed a combination of T-2, HT-2 and aflatoxin. Reduced glutathione content of the heart was higher in the T-2 + HT-2 group than in the control group. Mycotoxin contamination had no effect on glutathione peroxidase (GSH-Px) activity in comparison to the control, but significantly lower GSH-Px activity was found in the heart of chickens in the T-2 + HT-2 + AFB1group than in the T-2 + HT-2 group. In this study, T-2 + HT-2 toxin and aflatoxin B1contamination of the diets did not affect the production traits adversely and did not exert additive effects on lipid peroxidation and on the glutathione redox system.
Impact of the GSM Mobile Phone Network on the Speech Signal – Some Preliminary Findings
Authors: Guillemin Bernard John , Watson Catherine
Published: March 2009

The landline and mobile phone networks are very different in the manner in which they handle and process the speech signal, with consequential differences in their impact on the speech spectrum as well as on the acoustic parameters of interest in the forensic arena. This paper overviews the key features of both networks which give rise to these differences. Some findings are then presented showing the impact of the mobile network on fundamental frequency, F0, as well as on the first three formants in vowel sounds. It is shown that though the impact on F0 is not great, the impact on the formant frequencies, and particularly on the measurements of these determined using automated formant trackers, can be significant. These early findings are considered to be of great importance to forensic practitioners relying on acoustic measurements as part of their investigations.
New iodine derivatives of flavonol and isoflavone
Authors: Carvalho Mário G. de , Silva Virginia C. da , Silva Tânia M.S. da , Camara Celso A. , Braz-Filho Raimundo
Published: March 2009

The reaction of the flavonol 3,7,3', 4'-tetra-O-methylquercetin (1) and of the isoflavone 7,4'-di-O-methylgenistein (2) with alkaline iodine in methanol afforded four new iodine derivatives: 8-iodo-5-hydroxy-3,7,3', 4'-tetramethoxy- flavone (1a) and 6-iodo-5-hydroxy-3,7,3', 4'-tetramethoxyflavone (1b) from 1; 2 afforded a mixture of two compounds, identified as a racemic mixture of (±)-trans-5-hydroxy-2,3,7,4'-tetramethoxy-8-iodo-isoflavanone (2a) and (±)-trans-5-hydroxy-2,3,7,4'-tetramethoxy-6,8-diiodo-isoflavanone (2b). The formation of these different products reveals a significant difference involving the chemical interaction between the reactive site of α, β-unsaturated ketones of flavonol and isoflavone under the tested reaction conditions (using I2/KOH/MeOH). Furthermore, the trans stereo selectivity is noteworthy in the nucleophylic addition of methanol at the isoflavone α, β-unsaturated system. The structures were identified on the basis of spectral data, mainly 1D and 2D NMR and mass spectra.
Modulatory effects of rutin on biochemical and hematological parameters in hypercholesterolemic Golden Syrian hamsters
Authors: Kanashiro Alexandre , Andrade Daiani C.O. , Kabeya Luciana M. , Turato Walter M. , Faccioli Lucia H. , Uyemura Sérgio A. , Lucisano-Valim Yara M.
Published: March 2009

Flavonoids have been reported to exhibit several pharmacological properties, mainly in cardiovascular and inflammatory diseases. In the present study, we observed that rutin, a known glycosylated flavonoid isolated from Dimorphandra mollis, had a lowering effect on plasma triglyceride levels of diet-induced hypercholesterolemic Golden Syrian hamsters, but did not change total cholesterol and high-density lipoprotein cholesterol levels. Moreover, high-fat or rutin supplemented diets showed no immunotoxic effects, since no significant changes were observed on total white blood cells, granulocytes and mononuclear cells, as well as on the neutrophil apoptosis degree, when compared to untreated animals. Therefore, rutin seems to be a selective and non-toxic modulator of hypercholesterolemia, which can be promising for the development of new drugs.