bluuebunny/crossref_metadata_2025 huggingface dataset:
Transgenic Mice with Chronic NGF Deprivation and Alzheimer's Disease-Like Pathology Display Hippocampal Region-Specific Impairments in Short- and Long-Term Plasticities
Authors: Houeland Gry , Romani Armando , Marchetti Cristina , Amato Gianluca , Capsoni Simona , Cattaneo Antonino , Marie Hélène
Published: September 2010

The etiology of Alzheimer's disease (AD) remains elusive. The “amyloid” hypothesis states that toxic action of accumulated β-amyloid peptide (Aβ) on synaptic function causes AD cognitive decline. This hypothesis is supported by analysis of familial AD (FAD)-based transgenic mouse models, where altered amyloid precursor protein (APP) processing leads to Aβ accumulation correlating with hippocampal-dependent memory deficits. Some studies report prominent dentate gyrus (DG) glutamatergic plasticity alterations in these mice, while CA1 plasticity remains relatively unaffected. The “neurotrophic unbalance” hypothesis, on the other hand, states that AD-related loss of cholinergic signaling and altered APP processing are due to alterations in nerve growth factor (NGF) trophic support. This hypothesis is supported by analysis of the AD11 mouse, which exhibits chronic NGF deprivation during adulthood and displays AD-like pathology, including Aβ accumulation and hippocampal-dependent memory deficits. In this study, we analyzed CA1 and DG glutamatergic plasticity in AD11 mice to evaluate whether these mice also share with FAD models a common phenotype in hippocampal synaptic dysfunction. We report that AD11 mice display age-dependent short- and long-term DG plasticity deficits, while CA1 plasticity remains relatively spared. We also report that both structures exhibit enhanced glutamatergic transmission under lower, yet physiological, neurotransmitter release conditions, a defect that should be considered when further evaluating hippocampal synaptic deficits underlying AD pathology. We conclude that severe deficits in DG plasticity represent another common denominator between these two etiologically different types of AD mouse models, independent of the initial insult (overexpression of FAD mutation or NGF deprivation).
Maternal Care and DNA Methylation of a Glutamic Acid Decarboxylase 1 Promoter in Rat Hippocampus
Authors: Zhang Tie-Yuan , Hellstrom Ian C. , Bagot Rosemary C. , Wen Xianglan , Diorio Josie , Meaney Michael J.
Published: September 2010

Parenting and the early environment influence the risk for various psychopathologies. Studies in the rat suggest that variations in maternal care stably influence DNA methylation, gene expression, and neural function in the offspring. Maternal care affects neural development, including the GABAergic system, the function of which is linked to the pathophysiology of diseases including schizophrenia and depression. Postmortem studies of human schizophrenic brains have revealed decreased forebrain expression of glutamic acid decarboxylase 1 (GAD1) accompanied by increased methylation of aGAD1promoter. We examined whether maternal care affectsGAD1promoter methylation in the hippocampus of adult male offspring of high and low pup licking/grooming (high-LG and low-LG) mothers. Compared with the offspring of low-LG mothers, those reared by high-LG dams showed enhanced hippocampalGAD1mRNA expression, decreased cytosine methylation, and increased histone 3–lysine 9 acetylation (H3K9ac) of theGAD1promoter. DNA methyltransferase 1 expression was significantly higher in the offspring of low- compared with high-LG mothers. Pup LG increases hippocampal serotonin (5-HT) and nerve growth factor-inducible factor A (NGFI-A) expression. Chromatin immunoprecipitation assays revealed enhanced NGFI-A association with and H3K9ac of theGAD1promoter in the hippocampus of high-LG pups after a nursing bout. Treatment of hippocampal neuronal cultures with either 5-HT or an NGFI-A expression plasmid significantly increasedGAD1mRNA levels. The effect of 5-HT was blocked by a short interfering RNA targeting NGFI-A. These results suggest that maternal care influences the development of the GABA system by alteringGAD1promoter methylation levels through the maternally induced activation of NGFI-A and its association with theGAD1promoter.
Specificity of Human Parietal Saccade and Reach Regions during Transcranial Magnetic Stimulation
Authors: Vesia Michael , Prime Steven L. , Yan Xiaogang , Sergio Lauren E. , Crawford J. Douglas
Published: September 2010

Single-unit recordings in macaque monkeys have identified effector-specific regions in posterior parietal cortex (PPC), but functional neuroimaging in the human has yielded controversial results. Here we used on-line repetitive transcranial magnetic stimulation (rTMS) to determine saccade and reach specificity in human PPC. A short train of three TMS pulses (separated by an interval of 100 ms) was delivered to superior parieto-occipital cortex (SPOC), a region over the midposterior intraparietal sulcus (mIPS), and a site close to caudal IPS situated over the angular gyrus (AG) during a brief memory interval while subjects planned either a saccade or reach with the left or right hand. Behavioral measures then were compared to controls without rTMS. Stimulation of mIPS and AG produced similar patterns: increased end-point variability for reaches and decreased saccade accuracy for contralateral targets. In contrast, stimulation of SPOC deviated reach end points toward visual fixation and had no effect on saccades. Contralateral-limb specificity was highest for AG and lowest for SPOC. Visual feedback of the hand negated rTMS-induced disruptions of the reach plan for mIPS and AG, but not SPOC. These results suggest that human SPOC is specialized for encoding retinally peripheral reach goals, whereas more anterior-lateral regions (mIPS and AG) along the IPS possess overlapping maps for saccade and reach planning and are more closely involved in motor details (i.e., planning the reach vector for a specific hand). This work provides the first causal evidence for functional specificity of these parietal regions in healthy humans.
GABAergic Synaptic Scaling in Embryonic Motoneurons Is Mediated by a Shift in the Chloride Reversal Potential
Authors: Gonzalez-Islas Carlos , Chub Nikolai , Garcia-Bereguiain Miguel Angel , Wenner Peter
Published: September 2010

Homeostatic synaptic plasticity ensures that networks maintain specific levels of activity by regulating synaptic strength in a compensatory manner. When spontaneous network activity was blockedin vivoin the embryonic spinal cord, compensatory increases in excitatory GABAergic synaptic inputs were observed. This homeostatic synaptic strengthening was observed as an increase in the amplitude of GABAergic miniature postsynaptic currents. We find that this process is mediated by an increase in chloride accumulation, which produces a depolarizing shift in the GABAergic reversal potential (EGABA). The findings demonstrate a previously unrecognized mechanism underlying homeostatic synaptic scaling. Similar shifts inEGABAhave been described following various forms of neuronal injury, introducing the possibility that these shifts inEGABArepresent a homeostatic response.
Lesions in Posterior Parietal Area 5 in Monkeys Result in Rapid Behavioral and Cortical Plasticity
Authors: Padberg Jeffrey , Recanzone Gregg , Engle James , Cooke Dylan , Goldring Adam , Krubitzer Leah
Published: September 2010

We examined the effects of focal lesions of posterior parietal area 5 in macaque monkeys on bimanual behavior performed with and without visual guidance. The animals were trained on two reaching tasks and one tactile texture discrimination task. Task 1 simply involved reaching toward and grasping a reward from one of five well positions. Task 2 required the monkey to use both hands simultaneously to obtain a reward. The tactile texture discrimination task required the monkey to signal the roughness of a passively delivered texture using its jaw. After lesions to area 5, the monkeys showed a decrease in hand use for tasks 1 and 2 and an inability to perform task 2 in specific locations in visual space. These deficits recovered within several days. No deficits were observed in the tactile texture discrimination task or in an analgesic control monkey. Electrophysiological recordings made just before the lesion, immediately after the lesion, and 2 months after the lesion demonstrated that cortical areas just rostral to the lesioned area 5, and areas 1 and 2, were topographically reorganized and that receptive fields for neurons in these fields changed location on the body surface. These cortical map changes are correlative and may, in part, contribute to the rapid behavioral recovery observed. The mechanism for such rapid changes may be the unmasking of existing divergent and convergent thalamocortical connections that are part of the normal cortical circuitry.
Weight Gain Is Associated with Reduced Striatal Response to Palatable Food
Authors: Stice Eric , Yokum Sonja , Blum Kenneth , Bohon Cara
Published: September 2010

Consistent with the theory that individuals with hypofunctioning reward circuitry overeat to compensate for a reward deficit, obese versus lean humans have fewer striatal D2 receptors and show less striatal response to palatable food intake. Low striatal response to food intake predicts future weight gain in those at genetic risk for reduced signaling of dopamine-based reward circuitry. Yet animal studies indicate that intake of palatable food results in downregulation of D2 receptors, reduced D2 sensitivity, and decreased reward sensitivity, implying that overeating may contribute to reduced striatal responsivity. Thus, we tested whether overeating leads to reduced striatal responsivity to palatable food intake in humans using repeated-measures functional magnetic resonance imaging. Results indicated that women who gained weight over a 6 month period showed a reduction in striatal response to palatable food consumption relative to weight-stable women. Collectively, results suggest that low sensitivity of reward circuitry increases risk for overeating and that this overeating may further attenuate responsivity of reward circuitry in a feedforward process.
CREB Binding Protein Is Required for Both Short-Term and Long-Term Memory Formation
Authors: Chen Guiquan , Zou Xiaoyan , Watanabe Hirotaka , van Deursen Jan M. , Shen Jie
Published: September 2010

CREB binding protein (CBP) is a transcriptional coactivator with histone acetyltransferase activity. Our prior study suggested that CBP might be a key target of presenilins in the regulation of memory formation and neuronal survival. To elucidate the role of CBP in the adult brain, we generated conditional knock-out (cKO) mice in which CBP is completely inactivated in excitatory neurons of the postnatal forebrain. Histological analysis revealed normal neuronal morphology and absence of age-dependent neuronal degeneration in theCBPcKO cerebral cortex.CBPcKO mice exhibited robust impairment in the formation of spatial, associative, and object-recognition memory. In addition to impaired long-term memory,CBPcKO mice also displayed deficits in short-term associative and object-recognition memory. Administration of a histone deacetylase inhibitor, trichostatin A, rescued the reduction of acetylated histones in theCBPcKO cortex but failed to rescue either short- or long-term memory deficits, suggesting that the memory impairment may not be caused by general reduction of histone acetyltransferase activity inCBPcKO mice. Further microarray and Western analysis showed decreased expression of calcium-calmodulin-dependent kinase isoforms and NMDA and AMPA receptor subunits in the cerebral cortex ofCBPcKO mice. Collectively, these findings suggest a crucial role for CBP in the formation of both short- and long-term memory.
Linked Control of Syllable Sequence and Phonology in Birdsong
Authors: Wohlgemuth Melville J. , Sober Samuel J. , Brainard Michael S.
Published: September 2010

The control of sequenced behaviors, including human speech, requires that the brain coordinate the production of discrete motor elements with their concatenation into complex patterns. In birdsong, another sequential vocal behavior, the acoustic structure (phonology) of individual song elements, or “syllables,” must be coordinated with the sequencing of syllables into a song. However, it is unknown whether syllable phonology is independent of the sequence in which a syllable is produced. We quantified interactions between phonology and sequence in Bengalese finch song by examining both convergent syllables, which can be preceded by at least two different syllables and divergent syllables, which can be followed by at least two different syllables. Phonology differed significantly based on the identity of the preceding syllable for 97% of convergent syllables and differed significantly with the identity of the upcoming syllable for 92% of divergent syllables. Furthermore, sequence-dependent phonological differences extended at least two syllables away from the convergent or divergent syllable. To determine whether these phenomena reflect differences in central control, we analyzed premotor neural activity in the robust nucleus of the arcopallium (RA). Activity associated with a syllable varied significantly depending on the sequence in which the syllable was produced, suggesting that sequence-dependent variations in premotor activity contribute to sequence-dependent differences in phonology. Moreover, these data indicate that RA activity could contribute to the sequencing of syllables. Together, these results suggest that, rather than being controlled independently, the sequence and phonology of birdsong are intimately related, as is the case for human speech.
Unimodal Responses Prevail within the Multisensory Claustrum
Authors: Remedios Ryan , Logothetis Nikos K. , Kayser Christoph
Published: September 2010

The claustrum receives afferent inputs from multiple sensory-related brain areas, prompting speculation about a role in integrating information across sensory modalities. Here we directly test this hypothesis by probing neurons in the primate claustrum for functional characteristics of multisensory processing. To this end we recorded neuronal responses to naturalistic audio-visual stimuli from the claustra of alert monkeys. Our results reveal the existence of distinct claustral zones comprised of unimodal neurons associated with the auditory and visual modalities. In a visual zone within the ventral claustrum neurons responded to visual stimuli but not to sounds, whereas in an auditory zone located within the central claustrum neurons responded to sounds but not to visual stimuli. Importantly, we find that neurons within either zone are not influenced by stimuli in the other modality and do not exhibit the typical response characteristics usually associated with multisensory processing. While these results confirm the notion of the claustrum as a multisensory structure per se, they argue against the hypothesis of the claustrum serving as an integrator of sensory information.
Medial Parietal Cortex Encodes Perceived Heading Direction in Humans
Authors: Baumann Oliver , Mattingley Jason B.
Published: September 2010

The ability to encode and update representations of heading direction is crucial for successful navigation. In rats, head-direction cells located within the limbic system alter their firing rate in accordance with the animal's current heading. To date, however, the neural structures that underlie an allocentric or viewpoint-independent sense of direction in humans remain unknown. Here we used functional magnetic resonance imaging (fMRI) to measure neural adaptation to distinctive landmarks associated with one of four heading directions in a virtual environment. Our experiment consisted of two phases: a “learning phase,” in which participants actively navigated the virtual maze; and a “test phase,” in which participants viewed pairs of images from the maze while undergoing fMRI. We found that activity within the medial parietal cortex—specifically, Brodmann area 31—was modulated by learned heading, suggesting that this region contains neural populations involved in the encoding and retrieval of allocentric heading information in humans. These results are consistent with clinical case reports of patients with acquired lesions of medial posterior brain regions, who exhibit deficits in forming and recalling links between landmarks and directional information. Our findings also help to explain why navigation disturbances are commonly observed in patients with Alzheimer's disease, whose pathology typically includes the cortical region we have identified as being crucial for maintaining representations of heading direction.
Genetic Deletion of Paired Immunoglobulin-Like Receptor B Does Not Promote Axonal Plasticity or Functional Recovery after Traumatic Brain Injury
Authors: Omoto Shusaku , Ueno Masaki , Mochio Soichiro , Takai Toshiyuki , Yamashita Toshihide
Published: September 2010

The rewiring of neural networks is a fundamental step in recovering behavioral functions after brain injury. However, there is limited potential for axonal plasticity in the adult CNS. The myelin-associated proteins Nogo, myelin-associated glycoprotein (MAG), and oligodendrocyte myelin glycoprotein (OMgp) are known to inhibit axonal plasticity, and thus targeting the inhibitory pathways they participate in is a potential means of promoting plasticity and functional recovery. Each of Nogo, MAG, and OMgp interacts with both the Nogo receptor (NgR) and paired immunoglobulin-like receptor B (PirB). Here, we determined whether blocking PirB activity enhances axonal reorganization and functional recovery after cortical injury. We found that axons of the contralesional corticospinal tract sprouted into the denervated side of the cervical spinal cord after unilateral injury of the motor cortex. The extent to which this axonal reorganization occurred was far greater in mice lesioned during early postnatal days than in mice lesioned at an age when myelin had begun to form. This suggests that myelin-associated proteins might limit axonal remodelingin vivo. However, the number of sprouting fibers within either the corticospinal or corticorubral tract was not enhanced in PirB−/−mice. Blocking PirB signaling also failed to enhance functional recovery with three motor tests. Our results suggest that blocking the function of PirB is not sufficient to promote axonal reorganization or functional recovery after cortical injury.
The Src Homology 2 Domain Protein Shep1 Plays an Important Role in the Penetration of Olfactory Sensory Axons into the Forebrain
Authors: Wang Lei , Vervoort Virginie , Wallez Yann , Coré Nathalie , Cremer Harold , Pasquale Elena B.
Published: September 2010

Shep1 is a multidomain signaling protein that forms a complex with Cas, a key scaffolding component of integrin signaling pathways, to promote the migration of non-neuronal cells. However, the physiological function of Shep1 in the nervous system remains unknown. Interestingly, we found that Shep1 and Cas are both concentrated in the axons of developing olfactory sensory neurons (OSNs). These neurons extend their axons from the olfactory epithelium to the olfactory bulb located at the anterior tip of the forebrain. However, in developing Shep1 knock-out mice, we did not detect penetration of OSN axons across the pial basement membrane surrounding the olfactory bulb, suggesting that Shep1 function is important for the establishment of OSN connections with the olfactory bulb. Interestingly, we observed reduced levels of Cas tyrosine phosphorylation in OSN axons of Shep1 knock-out mice, suggesting compromised Cas signaling function. Indeed, when embedded in a three-dimensional gel of basement membrane proteins, explants from Shep1 knock-out olfactory epithelium extend neuronal processes less efficiently than explants from control epithelium. Furthermore, ectopic expression of Shep1 in non-neuronal cells promotes cell migration through a collagen gel. Later in development, loss of Shep1 function also causes a marked reduction in olfactory bulb size and disruption of bulb lamination, which may be primarily attributable to the defective innervation. The greatly reduced OSN connections and hypoplasia of the olfactory bulb, likely resulting in anosmia, are reminiscent of the symptoms of Kallmann syndrome, a human developmental disease that can be caused by mutations in a growing number of genes.
Impaired Efficiency of Functional Networks Underlying Episodic Memory-for-Context in Schizophrenia
Authors: Wang Liang , Metzak Paul D. , Honer William G. , Woodward Todd S.
Published: September 2010

Memory for context and episodic memory have been identified as primary contributors to cognitive impairments in schizophrenia. This study examined neural networks involved in episodic memory-for-context in schizophrenia using a multimodal strategy including a graph theoretical approach, combined with an assessment of the contribution of structural impairments to disruption in the efficiency of functional brain networks. Twenty-three patients with schizophrenia and 33 healthy controls performed an episodic memory-for-context task while undergoing functional magnetic resonance imaging scanning. Graph theory was used to characterize the small-world properties of functional connections between activated regions, and a morphometric analysis was used to investigate schizophrenia-related structural deficits. Similar functional activations were identified in the two groups; however, although small-world properties were present in the topological organization of the functional networks in both groups, significant reductions in local, but not global, efficiency were observed in the schizophrenia group. Several key network “hub” regions related to recollection, such as the bilateral dorsal anterior cingulate gyrus, showed reduced gray matter volume in schizophrenia patients. These findings suggest that loss of gray matter volume may contribute to local inefficiencies in the architecture of the network underlying memory-for-context in schizophrenia.
Diabetes-Associated SorCS1 Regulates Alzheimer's Amyloid-β Metabolism: Evidence for Involvement of SorL1 and the Retromer Complex
Authors: Lane Rachel F. , Raines Summer M. , Steele John W. , Ehrlich Michelle E. , Lah James A. , Small Scott A. , Tanzi Rudolph E. , Attie Alan D. , Gandy Sam
Published: September 2010

SorCS1 and SorL1/SorLA/LR11 belong to the sortilin family of vacuolar protein sorting-10 (Vps10) domain-containing proteins. Both are genetically associated with Alzheimer's disease (AD), andSORL1expression is decreased in the brains of patients suffering from AD.SORCS1is also genetically associated with types 1 and 2 diabetes mellitus (T1DM, T2DM). We have undertaken a study of the possible role(s) for SorCS1 in metabolism of the Alzheimer's amyloid-β peptide (Aβ) and the Aβ precursor protein (APP), to test the hypothesis thatSorcs1deficiency might be a common genetic risk factor underlying the predisposition to AD that is associated with T2DM. Overexpression of SorCS1cβ-myc in cultured cells caused a reduction (p= 0.002) in Aβ generation. Conversely, endogenous murine Aβ40and Aβ42levels were increased (Aβ40,p= 0.044; Aβ42,p= 0.007) in the brains of femaleSorcs1hypomorphic mice, possibly paralleling the sexual dimorphism that is characteristic of the genetic associations ofSORCS1with AD and DM. Since SorL1 directly interacts with Vps35 to modulate APP metabolism, we investigated the possibility that SorCS1cβ-myc interacts with APP, SorL1, and/or Vps35. We readily recovered SorCS1:APP, SorCS1:SorL1, and SorCS1:Vps35 complexes from nontransgenic mouse brain. Notably, total Vps35 protein levels were decreased by 49% (p= 0.009) and total SorL1 protein levels were decreased by 29% (p= 0.003) in the brains of femaleSorcs1hypomorphic mice. From these data, we propose that dysfunction of SorCS1 may contribute to both the APP/Aβ disturbance underlying AD and the insulin/glucose disturbance underlying DM.
Sol-gel synthesized NaLu1-xYbx(WO4)2 heteroepitaxial films for laser applications
Authors: Han Xiumei , Zaldo Carlos
Published: September 2010

NaLu1-xYbx(WO4)2 films have been prepared by spin coating of sol-gel precursor solutions and thermal annealing between 400 and 800 °C. Films obtained on sapphire have a dense and transparent ceramic microstructure and photoluminescence properties similar to those of single crystals with same composition. The application of these films as laser media is envisaged.
Detecting Insect Infestation: A Novel Application of Carbon/Polyethylene-co-vinyl Acetate Sensors
Authors: Weerakoon Kanchana Anuruddika , Chin Bryan A
Published: September 2010

Plants, when attacked by herbivores emit plant volatile compounds as a defensive mechanism to protect themselves from herbivores and parasites. Secreting these volatiles is not only toxic towards these insects but also aids enemies of the herbivores to recognize infested plants to locate their prey. A low mass fraction carbon black/polyethylene-co-vinylacetate composite sensor was designed and fabricated to detect insect infestation. This sensor was cost efficient, easy to fabricate and was highly stable in air. When an organic vapor is present, the carbon/polymer active layer swells creating a discontinuity in the conducting pathway between adjacent carbon particles, increasing the resistance of the film. When the analyte is no longer present, the polymer will return to its original state, showing a decrease in resistance. A variety of Carbon/black polymer sensors with varying chemical characteristics could be created by using different polymer matrices. Polyethylene-co-vinyl acetate was chosen as the best polymer for this particular application based on its swelling ability in the presence of plant volatiles compared to other polymers. When the carbon concentration of the active layer was low enough to be near the percolation threshold, the sensor can be used as a “chemical switch”. The resistance of the sensor increased significantly mimicking a “switch off” response when exposed to the analyte vapor. When the analyte vapor was no longer present the sensor returned back to its original condition, showing a “switch on” response. The percolation point was obtained when the carbon concentration of the carbon/polymer composite was kept between 0.5-1 wt%. The sensor was tested and found to be sensitive to a variety of volatile organic compounds emitted during insect infestation including γ-terpinene, α-pinene, p-cymene, farnesene, and limonene and cis-hexenyl acetate.
Bio-composite Materials for the Detection of Estrogen in Water Using Piezoresistive Microcantilever Sensors
Authors: Porter Timothy L. , Vail Tim , Propper Catherine , Islam Nazmul
Published: September 2010

Embedded piezoresistive microcantilever (EPM) sensors were used to detect the presence of the compound estrogen in water samples. The sensor was fabricated with a host material hydrogel (Hypol) functionalized with estrogen antibody. This sensor was able to detect 1 ppm of estrogen in water, responding almost immediately to the estrogen addition, with a full sensor response (saturation) occurring after two minutes of exposure.
A Biosensor System for the Detection of Salmonella Typhimurium Using Multiple Phage-based Magnetoelastic Biosensors
Authors: Shen Wen , Li Yugui , Chen Huiqin , Horikawa Shin , Chin B. A.
Published: September 2010

Magnetoelastic (ME) sensors provide a fast, sensitive method to detect bacteria with smaller sensors have higher mass sensitivity for detecting lower concentrations of bacteria. However, signals from smaller sensors are weaker and have more noise due to manufacturing defects. In this paper, we present a biosensor system for the detection of Salmonella typhimurium using multiple magnetoelastic sensors, each with the size of 2000 × 400 × 30 μm. The sensors are immobilized with E2 phage, which specifically binds with S. typhimurium. Unlike traditional methods, our system uses a step pulse to “shock” the sensor, causing it to vibrate at its natural resonance frequency and produce a signal in the pickup coil due to reverse magnetostriction. A Fast Fourier Transform (FFT) was used to determine the resonance frequency. As the biosensor captures S. typhimurium cells, its mass increases with a corresponding decrease of its resonance frequency.The detection system was composed of one coil with a reference sensor to monitor stability, and another coil with three measurement sensors separated in three tubes for simultaneous detection of bacteria. With multi-sensors the effect of a manufacturing defect is decreased and we get the benefit of averaging for more accurate and reliable results. Stability tests show that the variance of frequency detection is less than 122 ppm of its resonance frequency. SEM pictures of the sensor surface show a uniform binding of S. typhimurium cells. Cells were counted and the mass change calculated. The measured frequency change corresponds well to the theoretical change. The results show that the multiple phage based ME biosensors are able to simultaneously detect S. typhimurium and offer good sensitivity and reliability of detection.
Local Electromechanical Properties of CaCu3Ti4O12 Ceramics
Authors: Tararam Ronald , Bdikin Igor , Varela Jose , Bueno Paulo R , Kholkin Andrei L.
Published: September 2010

Scanning probe microscopy (SPM) was used to probe piezoelectric vibrations and local conductivity in CaCu3Ti4O12(CCTO) ceramics at room temperature. Piezoelectric contrast was observed on the polished surfaces of CCTO in both vertical (out-of-plane) and lateral (in-plane) modes and depended on the grain orientation varying in sign and amplitude. The piezoelectric contrast is shown to be controlled by the electrical bias (local poling) and displayed a ferroelectric-like reversible hysteresis accompanied with a change of the phase of piezoelectric signal. Flexoelectric effect (strain-gradient-induced polarization) due to surface relaxation was invoked to explain the observed contrast inside the grains.
Structure/Property Relations in Bulk Versus Solution Derived Proton Conducting Ceramics of the Form SrCe0.95Yb0.05O3 With Applications in Membrane Separations
Authors: Brinkman Kyle , Fox Elise B , Korinko Paul , Lascola Robert , Liu Qiang , Chen Fanglin
Published: September 2010

Membrane separations are a key enabling technology for future energy conversion devices. Ionic transport membranes must have both proton and electronic conductivity to function as hydrogen separation membranes without an external power supply. A technical obstacle to material modification by compositional changes is that the hydrogen flux through a dense membrane is a function of both the proton ionic conductivity and the electronic conductivity. An alternative way to modify the materials conductivity without changing the ratio of the chemical constituents is by altering the microstructure. In this study, SrCe0.95Yb0.05O3 was produced by conventional mixed oxide bulk ceramic techniques and chemical solution routes self-rising approaches using urea as the leavening agent. In conventional ceramic processing routes, the perovskite phase was observed to form at temperatures near 1300oC, while solution techniques resulted in perovskite phase formation starting near 1000oC with complete phase transformations occurring at 1100oC. Thermogravimetric analysis (TGA) was conducted in various gas atmospheres resulting in bulk oxide route powders exhibiting a 0.6% weight loss at 800oC under a nitrogen environment as compared to chemically derived powders which displayed weight losses on the order of 3.4%.The increased weight loss observed in chemically derived SrCe0.95Yb0.05O3 is correlated with an increase in the number of electron charge carriers and results in elevated electronic conduction. This study will report on the development of structure property relations in the model proton conducting ceramic system SrCe0.95Yb0.05O3.
Fabrication of Electrode With 3 Dimensionally Ordered Structure for All-Solid-State Battery
Authors: Kotobuki Masashi , Kanamura Kiyoshi
Published: September 2010

Fabrication of all-solid-state Li battery has been strongly required to overcome safety issue of present Li battery. One of promising structures for ceramics electrolyte in all-solid-state battery is 2-layered structure composed of 3 dimensionally ordered macroporous layer (3DOM) and dense layer. In this study, we prepared LLT ceramics electrolyte with the 2-layered structure by suspension filtration method. Thicknesses of the dense and the porous layers were about 17 and 111 μm, respectively. The porous layer involved uniform pores of 1.8 μm in diameter. An electrochemical property of LiMn2O4/2-layered LLT composite, prepared by impregnation of precursor sol for LiMn2O4 into the pores followed by calcination, was tested. A rechargeable behavior of the composite electrode was clearly observed. From this result, it can be said that the composite can work as rechargeable battery. The discharge capacity of the composite was 27 mA h g-1.
Enhancement of On-chip Bioassay Efficiency With Electrothermal Effect
Authors: Huang K. R. , Chang J. S. , Chao Sheng Der , Wu K. C.
Published: September 2010

We have performed the finite element simulations to study the binding reaction kinetics of the analyte-ligand protein pairs, C-reactive protein (CRP) and anti-CRP, in a reaction chamber of a biosensor. For diffusion limited reactions, diffusion boundary layers often develop on the reaction surface, thus hindering the reaction. To enhance the efficiency of a biosensor, a non-uniform AC electric field is applied to induce the electrothermal force which stirs the flow field. Biosensors with different arrangements of the electrode pairs and the reaction surface are designed to study the effects of geometric configurations on the binding efficiency. The maximum initial slope of the binding curve can be 6.94 times of the field-free value in the association phase, under an AC field of 15 rms and an operating frequency of 100 kHz. With the electrothermal effect, it is possible to use a slower flow and save much sample consumption without sacrificing the performance of a biosensor. Several design factors not studied in our previous works such as the thermal boundary conditions are discussed.
Experimental Characterization of the Whipping Instability of Charged Microjets in Liquid Baths
Authors: Riboux Guillaume , Gómez-Marín Álvaro , Barrero Antonio , Fernández-Nieves Alberto , Loscertales Ignacio G.
Published: September 2010

Capillary liquid flows have shown their ability to generate micro and nano-structures which can be used to synthesize material in the micro or nanometric size range. For instance, electrified capillary liquid jets issued from a Taylor are broadly used to spin micro and nanofibers when the liquid consists of a polymer solution or melt, a process termed electrospinning. In this process, the electrified capillary jet may develop a nonaxisymmetric instability, usually referred to as whipping instability, which very efficiently transforms electric energy into stretching energy, thus leading to the formation of extremely thin polymer fibers. Even though non axysimmetric instabilities of electrified jets were first investigated some decades ago, the existing theoretical models provide a qualitative understanding of the phenomenon but none of them is accurate enough when compared with experimental results. This whipping instability usually manifests itself as fast and violent lateral motion of the charged jet, which makes it difficult its characterization in the laboratory. However, this instability also develops when electrospinning is performed within a liquid bath instead of air. Although it is essentially the same phenomenon, the frequency of the whipping oscillations is much slower in the former case than in the latter, thus allowing detailed experimental characterization of the whipping instability. Furthermore, since the outer fluid is a liquid, its density and viscosity may now be used to influence the dynamics of the electrified capillary jet. In this work we present and rationalize the experimental data collecting the influence of the main parameters on the whipping characteristics of the electrified jet (frequency, amplitude, etc.).
Toward a Merged Microfluidic/Microelectrode Array Device for Culture of Unidirectional Neural Network
Authors: Mo Alexander , Heilshorn Sarah
Published: September 2010

Traditional neural cultures are formed from disassociating primary neurons that are sourced from animals. However by disassociating them, any larger organizational structure between the neurons is lost. In an effort to regain some of the lost organization a device that is capable of recreating and monitoring a unidirectional connection between two populations is proposed. Initial validation toward a fully functional device is presented. Using soft lithography techniques, a microfluidic chip has been designed and produced with a design conducive for facilitating such a neuron culture. Using a specialized adhesive method, this chip can be attached and removed from a commercially available microelectrode array. Finally, cell viability is demonstrated using the PC12 neuron-like cell line after exploring several device configurations. Further efforts will be focused on primary neuron culture and establishment of a unidirectional network.
Control of the Surface Properties of Microfludic Devices by Using Polyelectrolyte Multilayer Coatings
Authors: Park Hyun , An Yoo-Jin , Yang Sung Yun
Published: September 2010

Recently, more studies have been conducted in chemical and biological applications using microfluidic or nanofluidic devices.1 Polymer-based materials have been newly developed in this field due to the great needs of easy processing, cost-effectiveness and clarity for the material. However, it is still challenging to control of the surface properties of these devices on demand. Especially, for biological analysis or detection, micro-fluidics should handle aqueous samples but, most of the current materials in use for micro-fluidic devices are relatively hydrophobic (such as PDMS, PMMA and cyclo-olefin-co polymer, etc). Therefore, they usually need an extra assistance rather than a capillary force to flow the aqueous samples. In this paper, we utilized layer-by-layer deposition of polymer to modify the surface of the micro-channel of the device in order to control surface properties of the micro-channel. We have been studied polyelectrolyte multilayer(PEM) coatings to control surface wettability of the open structures and found various hydrophilic films. Here we demonstrate polyelectrolyte multilayer film as an effective coating for inner surface of micro-fluidic devices to lowering the water contact angle, so that the aqueous fluid will travel smoothly with the channels. Compared to the other surface treatment method such as base cleaning or plasma irradiation, the PEM coating exhibit highly sustained water wettability. Polyelectrolytes used for this study are weak polyelectrolytes including biodegradable polymer such as poly(hyaluronic acid) (HA) for future biological applications.
Fabrication and Applications of Three Dimensional Porous Microwells
Authors: Randall Christina L , Kalinin Yevgeniy V , Azam Anum , Gracias David
Published: September 2010

In many biological applications, such as cell therapy and drug delivery, there is a need to enhance diffusion by enabling chemical transport in all three dimensions. We highlight this need by comparing diffusion in a conventional two-dimensional (2D) microwell with diffusion in a three-dimensional (3D) cubic microwell using numerical simulations. We also describe the fabrication of hollow polymeric (and biocompatible) cubic microwells and microwell arrays. We emphasize that since the assembly process is compatible with 2D lithographic patterning, porosity can be precisely patterned in all three dimensions. Hence, this platform provides considerable versatility for a variety of applications.
Doença do disco intervertebral cervical em cães: 28 casos (2003-2008)
Authors: Santini Giancarlo , Mazzanti Alexandre , Beckmann Diego V. , Santos Rosmarini P. , Pelizzari Charles , Polidoro Dakir , Baumhardt Raquel
Published: September 2010

O objetivo deste estudo foi identificar cães com doença do disco intervertebral (DDIV) cervical atendidos no Hospital Veterinário Universitário (HVU) da Universidade Federal de Santa Maria (UFSM) entre janeiro de 2003 e outubro de 2008 e obter informações a respeito de raça, sexo, idade, sinais neurológicos, resposta ao tratamento cirúrgico, complicações, tempo de recuperação funcional após a cirurgia e ocorrência de recidiva. Hiperestesia cervical foi observada em todos os cães (n=28). Quanto ao grau de disfunção neurológica foram verificados: grau I (8/28[28,5%]), grau II (3/28 [10,7%]), grau III (5/28[17,8%]) e grau V (12/2 [42,8%]). A duração dos sinais neurológicos antes da cirurgia em sete cães (25%) permaneceu por até 15 dias, em 14 cães (50%) entre 15 e 30 dias e nos outros sete cães (25%) por mais de 30 dias. A recuperação satisfatória e sem recidiva foi observada em todos os cães submetidos ao tratamento cirúrgico e que sobreviveram (n=21). Pode-se concluir que a DDIV cervical em nossa rotina acomete principalmente cães adultos, machos, de raças condrodistróficas e não condrodistróficas, incluindo as de grande porte; a hiperestesia cervical é a principal manifestação clínica; a técnica de fenda ventral promove recuperação funcional satisfatória e sem recidiva; as principais complicações trans-operatórias são a hemorragia do plexo venoso, a bradicardia e a hipotensão; e a duração dos sinais clínicos não interfere no tempo de recuperação pós-operatória dos cães.
Monitoração e avaliação clínica da eficácia da transfusão de sangue total e concentrado de hemácias em cães
Authors: Morikawa Marcel K. , Bochio Mariana M. , Pincelli Vanessa A. , Freire Roberta L. , Pereira Patrícia M.
Published: September 2010

A terapia transfusional tem grande potencial de salvar vidas na clínica de pequenos animais, e é usada principalmente na terapêutica de emergência em animais anêmicos, entretanto este procedimento está associado a vários riscos. Uma das formas de minimizá-los é pela monitoração constante durante a transfusão sanguínea, permitindo assim avaliar a melhora clínica do paciente. O objetivo deste trabalho foi avaliar a eficácia da transfusão de sangue total e de concentrado de hemácias em cães anêmicos, por meio da monitoração dos parâmetros vitais. Foram avaliadas 77 transfusões em cães, sendo 52 de sangue total armazenado e 25 de concentrado de hemácias. Durante todo o procedimento aferiu-se (a cada 15-30 minutos) a temperatura, frequência cardíaca, frequência respiratória e a coloração de mucosas dos pacientes, além do tempo de preenchimento capilar. Os resultados obtidos mostraram que ambos os componentes promoveram melhora dos parâmetros avaliados a partir de 45 minutos do início da transfusão sanguínea, principalmente da frequência cardíaca, coloração de mucosas e tempo de preenchimento capilar (p<0,05). A transfusão bem sucedida proporcionou melhora clínica aparente a partir de duas horas do início do procedimento.
Morfologia do tubo digestório da tartaruga verde (Chelonia mydas)
Authors: Magalhães Marcela S. , Freitas Maria de Lourdes , Silva Naisandra B. da , Moura Carlos Eduardo B. de
Published: September 2010

Para avaliar a morfologia do tubo digestório da tartaruga verde (Chelonia mydas) 10 animais, 9 juvenis e 1 adulto, foram analisados. A retirada dos órgãos digestórios procedeu-se após abertura do plastrão. A descrição e a medida do comprimento de cada órgão [esôfago, estômago, intestino delgado (ID) e intestino grosso (IG)] foram realizadas com o tubo digestório aberto. Os resultados mostraram que tanto nos animais juvenis como no adulto, o esôfago foi marcado pela presença de papilas pontiagudas em sua mucosa interna. O estômago apresentou aspecto saculiforme com fundo cego. No ID foi observado pregas reticulares na mucosa duodenal, enquanto o jejuno e do íleo mostrou pregas retilíneas longitudinais. O IG foi marcado pela alternância de regiões abauladas (haustros ou saculações) e estreitamentos. A microscopia do tudo digestório em C. mydas revelou esôfago com mucosa pregueada revestida por epitélio estratificado pavimentoso queratinizado. O estômago mostrou-se dividido em regiões: cárdica, fúndica, pilórica, as quais diferiam quanto ao número de glândulas e disposição da camada muscular. O ID apresentou-se marcado por vilosidades, e o IG por mucosa pregueada contendo glândulas na lâmina própria. A morfologia do tubo digestório da tartaruga verde mostrou-se adaptada ao seu hábito alimentar, possuindo especializações e um longo trato digestório que promove o aumento da superfície de absorção, já que seu alimento é de difícil digestão.
Estudo morfofuncional das glândulas mamárias de Mão Pelada, Procyon cancrivorus
Authors: Bellatine Tatiana , Mançanares Celina A.F. , Franciolli André Luis R. , Ambrósio Carlos E. , Martins Daniele S. , Miglino Maria Angélica , Carvalho Ana Flávia
Published: September 2010

Para a descrição macro e microscópica das glândulas mamárias foram utilizadas três fêmeas de Mão Pelada (Procyon cancrivorus). As amostras das glândulas foram processadas conforme técnicas rotineiras para histologia. As fêmeas estudadas apresentaram 3 pares de glândulas mamárias, sendo um par de glândula mamária abdominal cranial, um par de abdominal caudal e um par de inguinal. As papilas mamárias apresentaram formato pendular, como os canídeos domésticos. Microscopicamente, a glândula mamária apresentou da porção externa para a interna: epiderme (epitélio estratificado pavimentoso queratinizado), derme (tecido conjuntivo frouxo e tecido conjuntivo denso não modelado), fibras musculares lisas e ductos papilíferos que abrem em vários ósteos papilares em formato de "chuveiro". A porção secretora glandular era caracteristicamente túbulo alveolar, com células cuboidais dispostas em camada simples. Os resultados indicam que o conjunto glandular estudado é semelhante ao da cadela (Cannis familiaris) tanto em seu aspecto macroscópico quanto em seu aspecto microscópico, este fato sugere que podemos utilizar o Mão Pelada e o Cão como modelos similares de estudo, para identificação de patologias relacionadas a este sistema.
A hipótese da curva de Kuznets ambiental global: uma perspectiva econométrico-espacial
Authors: Carvalho Terciane Sabadini , Almeida Eduardo
Published: September 2010

Com o objetivo de averiguar a relação entre crescimento econômico e aquecimento global, este trabalho analisa uma curva de Kuznets ambiental por meio de uma abordagem econométrica espacial. Estimou-se uma CKA para emissões de CO2 per capita contra a renda per capita e seu termo ao quadrado, controlando, para exportações per capita, o consumo de energia per capita, uma dummy indicando os países que ratificaram o Protocolo de Kyoto. Os resultados sugerem que existem evidências de uma CKA na forma de "U" invertido, isto é, o crescimento reduz o impacto ambiental da atividade econômica. Porém, a incorporação do termo cúbico para a renda revela que as emissões eventualmente voltam a aumentar em níveis muito elevados de crescimento, fazendo que a CKA global estimada apresente o formato de "N". Outra descoberta foi a evidência de que os países que ratificaram o Protocolo reduziram significativamente suas emissões de CO2 per capita.