bluuebunny/crossref_metadata_2025 huggingface dataset:
MENSURAÇÃO DA SATISFAÇÃO DOS CONSUMIDORES DE POSTOS DE COMBUSTÍVEIS A PARTIR DE ATRIBUTOS QUALITATIVOS/EVALUATION OF CUSTOMER SATISFACTION WITH GAS STATIONS BASED ON QUALITATIVE ATTRIBUTES
Authors: Pinheiro Osvaldo Daniel dos Santos , Brambilla Flávio Régio
Published: April 2018

A satisfação do cliente está intimamente relacionada à qualidade dos atributos qualitativos que caracterizam os serviços de postos de combustíveis. Em decorrência disso, o objetivo do estudo foi medir a satisfação do consumidor de postos de combustível a partir da identificação de atributos que impactam os serviços na opinião do público-alvo e propor estratégias a partir dos atributos de maior insatisfação. Para tanto, a metodologia empregada na pesquisa envolveu inicialmente um estudo exploratório qualitativo, para identificar os atributos relevantes que impactam na satisfação dos clientes, através da Técnica do Incidente Crítico. A segunda etapa caracterizou-se por uma pesquisa descritiva quantitativa, com a elaboração de um questionário estruturado a partir das necessidades específicas identificadas na etapa exploratória, o que permitiu avaliar a satisfação dos consumidores a partir de uma amostra não probabilística de 300 consumidores de postos de combustíveis de Santa Cruz do Sul/RS. Os resultados culminaram numa lista de 11 atributos nos quais os clientes utilizam para avaliar a qualidade dos serviços prestados pelos postos, além dos percentuais de satisfação para cada variável (atributo) mensurado na avaliação da etapa descritiva. O Índice Global (Geral) de satisfação com os postos de combustíveis avaliados ficou com 83,70% de consumidores satisfeitos e 80,10% de consumidores que disseram que voltariam a comprar no mesmo posto onde abasteceram na última vez. Também foram sugeridas estratégias de melhoria aos serviços de postos de combustíveis com base nas variáveis de maior insatisfação.
GESTÃO DE MARKETING NA PEQUENA EMPRESA DE CONFECÇÃO DE VESTUÁRIOS/MARKETING MANAGEMENT IN A SMALL COMPANY OF CLOTHING MANUFACTURING
Authors: Cittadin Jackson , Sarquis Aléssio Bessa , Soares João Coelho , Cohen Eric David
Published: April 2018

A gestão de marketing tem papel relevante na pequena empresa de confecção de vestuários. Este estudo analisa como acontece a gestão de marketing na pequena empresa de confecção de vestuários da região AMREC, no Estado de Santa Catarina, Brasil. Trata-se de pesquisa exploratória, qualitativa e na forma de estudos de caso (múltiplos), com coleta de dados por meio de levantamento documental, entrevista em profundidade e observação direta. Os dados coletados foram analisados pela análise de conteúdo com categorização temática e uso do software Atlas TI. Os resultados contêm evidências relacionadas ao processo de planejamento de marketing, estratégias convencionais e contemporâneas utilizadas e processo de avaliação do desempenho de marketing. O estudo contribui para ampliar o conhecimento acadêmico sobre o tema, na medida em que permitiu coletar dados detalhados e evidências relacionadas à gestão de marketing na pequena empresa de confecção de vestuários e para a verificação de proposições teóricas e resultados de outros estudos.
A DINÂMICA DO TURISMO DE EVENTOS NO ESTADO DO RIO GRANDE DO SUL/BRASIL, NO CONTEXTO DO PLANEJAMENTO E DA COMUNICAÇÃO/THE DYNAMICS OF EVENT TOURISM IN THE STATE OF RIO GRANDE DO SUL/BRAZIL, IN THE CONTEXT OF PLANNING AND COMMUNICATION
Authors: Dotto Dalva Maria Righi , Cerezer Lilian Coradini , Pons Monica Elisa Dias , Denardin Adriele Carine Menezes
Published: April 2018

O turismo de eventos possui como principais peculiaridades, em relação às demais atividades turísticas, a duração limitada, o local específico, uma ou mais temáticas definidas e um elevado grau de interação entre os turistas e a comunidade do local em que o evento é desenvolvido. Decorrente da grande variedade de tipologias e atributos inerentes aos eventos, a sua organização pode ser considerada complexa, necessitando de planejamento e gestão adequada para a efetivação de seus objetivos. Visando compreender a dinâmica do turismo de eventos no estado do Rio Grande do Sul e, através de pesquisa exploratória, com abordagem de investigação qualitativa, este estudo teve como intenção realizar o mapeamento, caracterização e análise dos eventos realizados neste Estado. Os resultados demonstraram que, relativo à comunicação, constata-se uma baixa utilização do website da Secretaria Estadual de Turismo para a divulgação dos eventos realizados no Estado e, referente à organização, que os eventos com temáticas relacionadas ao movimento que enaltecem as raízes culturais do povo gaúcho, com atividades vinculadas a preservação das tradições como gastronomia, vestimentas e apresentações culturais, predominam em termos quantitativos e, também, possuem planejamento estruturado quanto ao calendário dos eventos e a diversidade de opções de atrativos.
MARKETING DE RELACIONAMENTO: ESTUDO EM EMPRESAS DE PEQUENO PORTE/RELATIONSHIP MARKETING: STUDY IN SMALL BUSINESS COMPANIES
Authors: Daradda Lidiane Fernanda Rocha , Miura Marcio Nakayama , Ribeiro Ivano
Published: April 2018

O presente trabalho analisou o marketing de relacionamento na fidelização dos associados da AMIC – Associação de Microempresas e Empresas de Pequeno Porte do Oeste do Paraná. A metodologia utilizada contemplou uma survey online aplicada aos associados da entidade, sendo realizada uma análise por meio de regressão linear múltipla. Identificou-se que existe uma relação positiva e significante entre o nível de comunicação utilizado pela associação e a fidelização dos associados. Já as variáveis: confiança, compromisso e tratamento de conflitos não influenciam na fidelização dos associados. Como principal contribuição, o estudo fornece indícios sobre o direcionamento do marketing de relacionamento ao terceiro setor e empresas de pequeno porte, tendo em vista os diferenciais que essa modalidade de organização possui em relação às empresas tradicionais.
Editorial
Authors: Silveira-Martins Elvis
Published: April 2018

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Influence of nerve on the formation and survival of acetylcholine receptor and cholinesterase patches on embryonic Xenopus muscle cells in culture
Authors: Moody-Corbett F , Cohen MW
Published: April 2018

Embryonic Xenopus muscle cells grown in culture develop discrete patches of high acetylcholine receptor (AChR) density. By following identified muscle cells after staining with fluorescent alpha- bungarotoxin, we have found that many of these AChR patches survive in a fixed position for several days. For AChR patches on the lower surface of the cell (the surface apposed to the culture dish), more than 60% of those which were followed beginning on day 2 survived for a further 4 days. The survival rate was greater when patches were followed from day 3 or later and was almost as high for AChR patches on the upper surface. New AChR patches also formed on all of the muscle cells. When muscle cells were cultured together with spinal cord cells, nerve-muscle contacts developed with a characteristic localization of AChRs along the path of contact. AChR patches did not form elsewhere on these contacted cells. Nerve-contacted muscle cells examined 2 to 3 days after adding spinal cord cells to established (2- to 5-day-old) muscle cultures also exhibited a marked reduction of AChR patches away from the site of contact. This reduction was not due to the nerve having contacted pre-existing AChR patches. Rather, the findings indicate that contact by an appropriate nerve inhibits the formation of AChR patches elsewhere on the contracted muscle cells and reduces the survival of pre-existing AChR patches. Nerve contact also inhibited the formation of cholinesterase (ChE) patches remote from the site of contact and appeared to cause some reduction in the survival of pre- existing ChE patches. Spontaneous twitching was not observed in these experiments, thereby indicating that the remote effects of nerve contact were not mediated by muscle action potentials or contraction. Such remote influences of the nerve may play a role in determining the pattern of innervation on individual muscle cells.
Temporal Regulation ofShaker- andShab-Like Potassium Channel Gene Expression in Single Embryonic Spinal Neurons during K+Current Development
Authors: Gurantz Devorah , Ribera Angeles B. , Spitzer Nicholas C.
Published: April 2018

A developmental increase in density of delayed rectifier potassium current (IKv) in embryonicXenopusspinal neurons shortens action potential durations and limits calcium influx governing neuronal differentiation. Although previous work demonstrates that maturation ofIKvdepends on general mRNA synthesis, it is not known whether increases in K+channel gene transcripts direct maturation of the current. Accordingly, the developmental appearance of specific Kv potassium channel genes was determined using single-cell reverse transcription-PCR techniques after whole-cell recording ofIKvduring the period of its development. Detection of a coexpressed housekeeping gene along with the potassium channel gene controlled for successful aspiration of cellular mRNA and allowed scoring of cells in which Kv gene transcripts were not detected. Diverse types ofXenopusspinal neurons exhibit homogenous development ofIKvbothin vivoand in culture. In contrast, transcripts of two genes encoding delayed rectifier current, Kv1.1 (Shaker) and Kv2.2 (Shab), are expressed heterogeneously during the period in which the current develops. Kv1.1 mRNA achieves maximal appearance in ∼30% of cells, whileIKvis immature; Kv2.2 mRNA appears later in ∼60% of mature neurons. Kv1.1 and 2.2 are thus candidates for generation ofIKv, and spinal neurons are a heterogeneous population with respect to potassium channel gene expression. Moreover, correlation of gene expression with current properties shows that neurons lacking Kv2.2 have a characteristic voltage dependence of activation ofIKv.
Projection Cells and Interneurons of the Lateral and Basolateral Amygdala: Distinct Firing Patterns and Differential Relation to Theta and Delta Rhythms in Conscious Cats
Authors: Paré Denis , Gaudreau Hélène
Published: April 2018

To study relations between the basolateral (BL) amygdaloid complex and major electroencephalogram (EEG) rhythms of the entorhinal cortex (delta and theta), neurons of the lateral and BL nuclei were recorded in conscious cats. An essential task to this end was to obtain criteria allowing the identification of projection cells and interneurons. BL projection cells, identified by their antidromic response to parahippocampal stimuli, generated stereotyped high-frequency bursts (2–4 spikes at 140–250 Hz), which repeated at low rates. Projection cells of the lateral nucleus were virtually silent, but their presence was disclosed by cortical-evoked responses. In both nuclei, the firing rates and/or responsiveness of projection cells increased from waking to slow-wave sleep (S). In contrast with projection cells, presumed interneurons discharged at high rates (∼10–15 Hz) and displayed various discharge patterns ranging from tonic to phasic. The bipartite classification of BL neurons on the basis of their discharge patterns and synaptic responses was supported by the differential relation existing between EEG rhythms and the activity of the two cell types. Indeed, fast-firing and bursting cells of the BL nucleus tended to fire on opposite phases of the delta oscillation of S and entorhinal theta oscillation of paradoxical sleep. The unusual state-related changes in activity displayed by lateral and BL neurons point to functional similarities between the amygdala and hippocampus. This idea is supported by the presence of coherent theta oscillations in the amygdalo-hippocampal circuit that might favor the emergence of recurring time windows when synaptic interactions will be facilitated in this limbic network.
The Vesicular Monoamine Transporter, in Contrast to the Dopamine Transporter, Is Not Altered by Chronic Cocaine Self-Administration in the Rat
Authors: Wilson Julie M. , Kish Stephen J.
Published: April 2018

Although much evidence suggests that the brain dopamine transporter (DAT) is susceptible to dopaminergic regulation, only limited information is available for the vesicular monoamine transporter (VMAT2). In the present investigation, we used a chronic, unlimited-access, cocaine self-administration paradigm to determine whether brain levels of VMAT2, as estimated using [3H]dihydrotetrabenazine (DTBZ) binding, are altered by chronic exposure to a dopamine uptake blocker. Previously, we showed that striatal and nucleus accumbens DAT levels, as estimated by [3H]WIN 35,428 and [3H]GBR 12,935 binding, are altered markedly using this animal model (Wilson et al., 1994). However, in sequential sections from the same animals, [3H]DTBZ binding was normal throughout the entire rostrocaudal extent of the basal ganglia (including striatum and nucleus accumbens), cerebral cortex, and diencephalon, as well as in midbrain and brainstem monoamine cell body regions, both on the last day of cocaine access and after 3 weeks of drug withdrawal. These data provide additional evidence that VMAT2, unlike DAT, is resistant to dopaminergic regulation.
Multiple Structural Elements Determine Subunit Specificity of Mg2+Block in NMDA Receptor Channels
Authors: Kuner Thomas , Schoepfer Ralf
Published: April 2018

In NMDA receptor channels, subtype-specific differences of Mg2+block are determined by the NR2 subunits. Channels assembled from the NR1-NR2A or NR1-NR2B subunits are blocked more strongly than channels formed by the NR1-NR2C or NR1-NR2D subunits, predominantly reflecting a difference in voltage dependence. A determinant of Mg2+block common to the NR2 subunits is located in the M2 domain (N-siteorQ/R/N-site). However, subunit-specific differences of block suggested that additional structural elements exist. Chimeric NR2 subunits were constructed by replacing segments of the least sensitive NR2C subunit with homologous segments of the most sensitive NR2B subunit. Mutant NR2 subunits were coexpressed with wild-type NR1 inXenopusoocytes, and Mg2+block was quantified. Replacement of the entire M1–M4 region resulted in a chimera with a sensitivity of Mg2+block similar to that of the NR2B wild type. Replacing smaller segments or introducing point mutations did not generate channels with Mg2+block characteristic of NR2B wild type. However, combining in a single chimera three small segments (M1, M2–M3 linker, M4), each independently mediating an increase in Mg2+block, produced channels close to NR2B wild type. Thus, differences in Mg2+block as controlled by the NR2 subunits cannot be explained by a single structural determinant in addition to theN-site. Moreover, three elements of the NR2 subunit are the major determinants of subtype-specific differences of Mg2+block in heteromeric NMDA receptor channels.
Identification and Characterization of a Ca2+-Sensitive Nonspecific Cation Channel Underlying Prolonged Repetitive Firing inAplysiaNeurons
Authors: Wilson Gisela F. , Richardson Frank C. , Fisher Thomas E. , Olivera Baldomero M. , Kaczmarek Leonard K.
Published: April 2018

The afterdischarge ofAplysiabag cell neurons has served as a model system for the study of phosphorylation-mediated changes in neuronal excitability. The nature of the depolarization generating the afterdischarge, however, has remained unclear. We now have found that venom fromConus textiletriggers a similar prolonged discharge, and we have identified a slow inward current and corresponding channel, the activation of which seems to contribute to the onset of the discharge. The slow inward current is voltage-dependent and Ca2+-sensitive, reverses at potentials slightly positive to 0 mV, exhibits a selectivity of K ≅ Na ≫ Tris > N-methyl-d-glucamine (NMDG), and is blocked by high concentrations of tetrodotoxin. Comparison of these features with those observed in channel recordings provides evidence that a Ca2+-sensitive, nonspecific cation channel is responsible for a slow inward current that regulates spontaneous repetitive firing and suggests that modulation of the cation channel underlies prolonged changes in neuronal response properties.
Functional Anatomy of a Prelearned Sequence of Horizontal Saccades in Humans
Authors: Petit Laurent , Orssaud Christophe , Tzourio Nathalie , Crivello Fabrice , Berthoz Alain , Mazoyer and Bernard
Published: April 2018

We have used positron emission tomography (PET) to study the functional anatomy of the repetition of a prelearned sequence of horizontal saccadic eye movements. Five subjects had to memorize a sequence of six successive horizontal saccades. The subjects were scanned in total darkness under three different conditions: at rest, during the execution of self-paced horizontal saccades, and while repeating a prelearned saccades sequence. The repetition of the prelearned saccades sequence led to specific normalized regional cerebral blood flow (NrCBF) increases at the depth of the superior frontal sulcus as well as at the rostral part of the supplementary motor area, whereas at the parietal level an important activation was observed in the intraparietal sulcus extending up to the precuneus. In addition, it was noticed that compared with the resting control condition, both oculomotor tasks activated a common set of cortical and subcortical areas. At the cortical level, this network was composed of the frontal eye fields, the supplementary eye fields, the median part of the cingulate gyrus, and the insula. At the subcortical level, the lenticular nucleus and the thalamus as well as the cerebellar vermis were activated consistently. A direct comparison of our results with those of other PET studies on spatial vision suggests that the dorsal visuospatial pathway could be extended toward the frontal premotor region. In such a scheme, visuospatial information computed in the intraparietal sulcus would be transmitted to the frontal premotor cortex to optimize a spatial-oriented behavior. This is consistent with the early proposal that perceptual and intentional components of spatial information are mediated through superior parietal and frontal areas, respectively.
Neural Agrin Activates a High-Affinity Receptor in C2 Muscle Cells that Is Unresponsive to Muscle Agrin
Authors: Bowen David C. , Sugiyama Janice , Ferns Michael , Hall Zach W.
Published: April 2018

During synaptogenesis, agrin, released by motor nerves, causes the clustering of acetylcholine receptors (AChRs) in the skeletal muscle membrane. Although muscle α-dystroglycan has been postulated to be the receptor for the activity of agrin, previous experiments have revealed a discrepancy between the biological activity of soluble fragments of two isoforms of agrin produced by nerves and muscles, respectively, and their ability to bind α-dystroglycan. We have determined the specificity of the signaling receptor by investigating whether muscle agrin can block the activity of neural agrin on intact C2 myotubes. We find that a large excess of muscle agrin failed to inhibit either the number of AChR clusters or the phosphorylation of the AChR induced by picomolar concentrations of neural agrin. These results indicate that neural, but not muscle, agrin interacts with the signaling receptor. Muscle agrin did block the binding of neural agrin to isolated α-dystroglycan, however, suggesting either that α-dystroglycan is not the signaling receptor or that its properties in the membrane are altered. Direct assay of the binding of muscle or neural agrin to intact myotubes revealed only low-affinity binding. We conclude that the signaling receptor for agrin is a high-affinity receptor that is highly specific for the neural form.
Determinants of Competitive Antagonist Sensitivity on Neuronal Nicotinic Receptor β Subunits
Authors: Harvey Scott C. , Luetje Charles W.
Published: April 2018

We constructed a series of chimeric and mutant neuronal nicotinic acetylcholine receptor β subunits to map amino acid residues that determine sensitivity to competitive antagonists. The β2 and β4 subunits form pharmacologically distinct receptors when expressed in combination with the α3 subunit inXenopusoocytes. At equipotent acetylcholine concentrations, α3β2 is 56-fold more sensitive to blockade by dihydro-β-erythroidine than is α3β4. The α3β2 combination is also sensitive to long-term blockade by neuronal bungarotoxin, whereas α3β4 is not. Pharmacological analysis of receptors formed by chimeric β subunits reveals that amino acid residues that determine both dihydro-β-erythroidine and neuronal bungarotoxin sensitivity are located within several sequence segments. The major determinant of sensitivity to both competitive antagonists is located between residues 54 and 63. A minor determinant of sensitivity to both antagonists lies between residues 1 and 54, whereas a minor determinant of NBT sensitivity lies between residues 74 and 80. Within region 54–63 of β2, mutant β2 subunits were used to identify threonine 59 as a residue critical in determining competitive antagonist sensitivity. Changing threonine 59 to lysine, as occurs in β4, causes a 9-fold decrease in dihydro-β-erythroidine sensitivity and a 71-fold decrease in neuronal bungarotoxin sensitivity. Changing polar threonine 59 to negatively charged aspartate causes a 2.5-fold increase in neuronal bungarotoxin sensitivity and has no effect on dihydro-β-erythroidine sensitivity.
Temporal Representations of Odors in an Olfactory Network
Authors: Laurent Gilles , Wehr Michael , Davidowitz Hananel
Published: April 2018

The responses of projection neurons in the antennal lobe of the locust brain (the functional analog of mitral–tufted cells in the vertebrate olfactory bulb) to natural blends and simple odors were studied with multiple intra- and extracellular recordingsin vivo. Individual odors evoked complex temporal response patterns in many neurons. These patterns differed across odors for a given neuron and across neurons for a given odor, but were stable for each neuron over repeated presentations (separated by seconds to minutes) of the same odor. The response of individual neurons to an odor was superimposed on an odor-specific coherent oscillatory population activity. Each neuron usually participated in the coherent oscillations during one or more specific epochs of the ensemble activity. These epochs of phase locking were reliable for each neuron over tens of repeated presentations of one odor. The timing of these epochs of synchronization differed across neurons and odors. Correlated activity of specific pairs of neurons, hence, generally occurred transiently during the population response, at times that were specific to these pairs and to the odor smelled. The field potential oscillations, therefore, fail to reveal a progressive transformation of the synchronized ensemble as the response to the odor unfolds. We propose that (1) odors are represented byspatiallyandtemporallydistributed ensembles of coherently firing neurons, and (2) the field potential oscillations that characterize odor responses in the olfactory system occur, at least in this animal, in parallel with a slower dynamic odor representation.
Homeostasis of Synaptic Transmission inDrosophilawith Genetically Altered Nerve Terminal Morphology
Authors: Stewart Bryan A. , Schuster Christoph M. , Goodman Corey S. , Atwood Harold L.
Published: April 2018

We present a new test of the hypothesis that synaptic strength is directly related to nerve terminal morphology through analysis of synaptic transmission atDrosophilaneuromuscular junctions with a genetically reduced number of nerve terminal varicosities. Synaptic transmission would decrease in target cells with fewer varicosities if there is a relationship between the number of varicosities and the strength of synaptic transmission. Animals that have an extreme hypomorphic allele of the gene for the cell adhesion molecule Fasciclin II possess fewer synapse-bearing nerve terminal varicosities; nevertheless, synaptic strength is maintained at a normal level for the muscle cell as a whole. Fewer failures of neurotransmitter release and larger excitatory junction potentials from individual varicosities, as well as more frequent spontaneous release and larger quantal units, provide evidence for enhancement of transmitter release from varicosities in the mutant. Ultrastructural analysis reveals that mutant nerve terminals have bigger synapses with more active zones per synapse, indicating that synaptic enlargement and an accompanying increase in synaptic complexity provide for more transmitter release at mutant varicosities. These results show that morphological parameters of transmitting nerve terminals can be adjusted to functionally compensate for genetic perturbations, thereby maintaining optimal synaptic transmission.
Synaptic Vesicle Movements Monitored by Fluorescence Recovery after Photobleaching in Nerve Terminals Stained with FM1-43
Authors: Henkel A. W. , Simpson L. L. , Ridge R. M. A. P. , Betz W. J.
Published: April 2018

We used the fluorescence recovery after photobleaching technique to monitor movements of synaptic vesicles in top views of living frog motor nerve terminals that had been prestained with the fluorescent dye FM1-43. In each experiment, a small portion of a single stained vesicle cluster was bleached with a laser and monitored subsequently for signs of recovery as neighboring, unbleached vesicles moved into the bleached region. In resting terminals, little or no recovery from photobleaching occurred. Repetitive nerve stimulation, which caused all fluorescent spots to grow dim as dye was released from exocytosing vesicles, did not promote recovery from photobleaching. Pretreatment with botulinum toxin (type A, C, or D) blocked exocytosis and destaining, but intense nerve stimulation still did not cause significant recovery in bleached regions. These results suggest that lateral movements of synaptic vesicles are restricted severely in both resting and stimulated nerve terminals.

We tested for laser-induced photodamage in several ways. Bleached regions could be restained fully with FM1-43, and these restained regions could be destained fully by nerve stimulation. Partially bleached regions could be destained, although the rate of destaining was lower than normal. Brisk recovery from photobleaching occurred after treatment with okadaic acid, which disrupts synaptic vesicle clusters and causes vesicles to spread throughout the nerve terminal. These results suggest that vesicle translocation and recycling machinery was intact in photobleached regions.
A Distinct Pattern of Trophic Factor Expression in Myelin-Deficient Nerves ofTremblerMice: Implications for Trophic Support by Schwann Cells
Authors: Friedman Hana C. Hyman , Jelsma Tony N. , Bray Garth M. , Aguayo Albert J.
Published: April 2018

Distal to a peripheral nerve transection, myelin degradation and Schwann cell (SC) proliferation are accompanied by a marked upregulation of brain-derived neurotrophic factor (BDNF) and a decrease of ciliary neurotrophic factor (CNTF) in non-neuronal cells. To investigate the role of SC differentiation in trophic factor regulation, we studied BDNF and CNTF expression in sciatic nerves fromTrembler-J(Tr-J) mice. In these animals, a mutation in thepmp-22gene causes a failure of myelination and continuous SC proliferation, but axonal continuity is preserved. In spite of the severe abnormalities inTr-Jnerves, BDNF levels remained as low as in the intact controls. Thus, the primary SC disorder inTr-Jproduces a different pattern of BDNF expression from that caused by axonal breakdown due to nerve transection. Furthermore, the upregulation of BDNF mRNA triggered by transection was 70-fold in control nerves, but only 30-fold inTr-Jsciatic nerves. Because these results raised the possibility that axonal loss may influence neurotrophin expression only in SCs that have differentiated toward a myelinating phenotype, we measured BDNF mRNA after axotomy in the cervical sympathetic trunk (CST), a predominantly unmyelinated autonomic nerve. In contrast to the sciatic nerves, the BDNF mRNA level barely increased in the injured CST, supporting the idea that not all SCs are equal sources of trophic molecules. InTr-Jsciatic nerves, CNTF mRNA levels were fourfold lower than normal, implying that the downregulation of this cytokine is a sensitive indicator of a spectrum of SC perturbations that affect myelinating cells.
Impaired Differentiation of Schwann Cells in Transgenic Mice with IncreasedPMP22Gene Dosage
Authors: Magyar Josef P. , Martini Rudolf , Ruelicke Thomas , Aguzzi Adriano , Adlkofer Katrin , Dembic Zlatko , Zielasek Jürgen , Toyka Klaus V. , Suter Ueli
Published: April 2018

An intrachromosomal duplication containing thePMP22gene is associated with the human hereditary peripheral neuropathy Charcot-Marie-Tooth disease type 1A, and PMP22 overexpression as a consequence of increasedPMP22gene dosage has been suggested as causative event in this frequent disorder of peripheral nerves. We have generated transgenic mice that carry additional copies of thepmp22gene to prove that increased PMP22 gene dosage is sufficient to cause PNS myelin deficiencies. Mice carrying approximately 16 and 30 copies of thepmp22gene display a severe congenital hypomyelinating neuropathy as characterized by an almost complete lack of myelin and marked slowing of nerve conductions. Affected nerves contain an increased number of nonmyelinating Schwann cells, which do not form onion bulbs but align in association with axons. The mutant Schwann cells are characterized by a premyelination-like state as indicated by the expression of embryonic Schwann cell markers. Furthermore, continued Schwann cell proliferation is observed into adulthood. We hypothesize that Schwann cells are impaired in their differentiation into the myelinating phenotype, leading to a disorder comparable to severe cases of hereditary motor and sensory neuropathies. Our findings, combined with the analysis of heterozygous and homozygous PMP22-deficient mice, indicate that aberrantpmp22gene copy numbers cause various forms of myelination defects.
Increased Susceptibility to Induction of Long-Term Depression and Long-Term Potentiation Reversal during Aging
Authors: Norris Christopher M. , Korol Donna L. , Foster Thomas C.
Published: April 2018

Homosynaptic long-term depression (LTD) and reversal of long-term potentiation (LTP) were examined extracellularly at CA3–CA1 synapses in stratum radiatum of slices from adult (6–9 months) and aged (20–24 months) Fischer 344 rats. Prolonged low-frequency stimulation (LFS) (900 pulses/1 Hz) of the Schaffer collaterals depressed the initial slope of the excitatory postsynaptic potential (EPSP) in aged but not adult rats. LTD at aged synapses was pathway-specific, persistent, and sensitive to the NMDA receptor antagonistdl-2-amino-5-phosphonopentanoic acid (AP5). Adult slices exhibited AP5-sensitive LTD in high [Ca2+] medium, whereas LTD in aged slices was blocked by high [Mg2+], suggesting that differences in Ca2+regulation may underlie susceptibility to LTD.

Despite age-related differences in LTD induction, no age difference in LTP magnitude was revealed. Additionally, LFS delivered 60 min after LTP induction resulted in similar LTP reversal for both age groups. Susceptibility differences to LTP reversal were indicated after multiple short-duration LFS bursts (30 pulses/1 Hz), with each burst separated by 10 min. Aged synapses exhibited significant reversal after a single burst and complete reversal after three LFS episodes. In adult slices, LTP reversal appeared after the fourth burst, and at no time was LTP depressed to initial baseline levels. This study provides the first characterization of homosynaptic LTD/LTP reversal in the aged animal and demonstrates that one form of plasticity, depression attributable to LFS, is increased during aging.
Mechanisms of H+and Na+Changes Induced by Glutamate, Kainate, and d-Aspartate in Rat Hippocampal Astrocytes
Authors: Rose Christine R. , Ransom Bruce R.
Published: April 2018

The excitatory transmitter glutamate (Glu), and its analogs kainate (KA), andd-aspartate (d-Asp) produce significant pH changes in glial cells. Transmitter-induced pH changes in glial cells, generating changes in extracellular pH, may represent a special form of neuronal–glial interaction. We investigated the mechanisms underlying these changes in intracellular H+concentration ([H+]i) in cultured rat hippocampal astrocytes and studied their correlation with increases in intracellular Na+concentration ([Na+]i), using fluorescence ratio imaging with 2′,7′-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) or sodium-binding benzofuran isophthalate (SBFI). Glu, KA, ord-Asp evoked increases in [Na+]i; Glu ord-Asp produced parallel acidifications. KA, in contrast, evoked biphasic changes in [H+]i, alkaline followed by acid shifts, which were unaltered after Ca2+removal and persisted in 0 Cl−-saline, but were greatly reduced in CO2/HCO−3-free or Na+-free saline, or during 4,4′-diisothiocyanato-stilbene-2,2′-disulphonic acid (DIDS) application. The non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocked KA-evoked changes in [H+]iand [Na+]i, indicating that they were receptor–ionophore mediated. In contrast, CNQX increased the [H+]ichange and decreased the [Na+]ichange induced by Glu.d-Asp, which is transported but does not act at Glu receptors, induced [H+]iand [Na+]ichanges that were virtually unaltered by CNQX. Our study indicates that [Na+]iincreases are not primarily responsible for Glu- or KA-induced acidifications in astrocytes. Instead, intracellular acidifications evoked by Glu ord-Asp are mainly caused by transmembrane movement of acid equivalents associated with Glu/Asp-uptake into astrocytes. KA-evoked biphasic [H+]ichanges, in contrast, are probably attributable to transmembrane ion movements mediated by inward, followed by outward, electrogenic Na+/HCO−3cotransport, reflecting KA-induced biphasic membrane potential changes.
Anatomical Demonstration of Ocular Dominance Columns in Striate Cortex of the Squirrel Monkey
Authors: Horton Jonathan C. , Hocking Davina R.
Published: April 2018

The squirrel monkey is the only primate reported to lack ocular dominance columns. Nothing anomalous about the visual capacity of squirrel monkeys has been found to explain their missing columns, leading to the suggestion that ocular dominance columns might be “an epiphenomenon, not serving any purpose” (Livingstone et al., 1995). Puzzled by the apparent lack of ocular dominance columns in squirrel monkeys, we made eye injections with transneuronal tracers in four normal squirrel monkeys. An irregular mosaic of columns, averaging 225 μm in width, was found throughout striate cortex. They were double-labeled by placing wheat germ agglutinin-horseradish peroxidase into the left eye and [3H]proline into the right eye. The tracers labeled opposite sets of interdigitating columns, proving they represent ocular dominance columns. The columns were much clearer in layer IVcα (magno-receiving) than IVcβ (parvo-receiving). In the lateral geniculate body, the parvo laminae showed extensive mixing of ocular inputs, suggesting that increased label spillover contributes to the blurred columns in layer IVcβ. The cytochrome oxidase (CO) patches were organized into distinct rows, but they bore no consistent relationship to the ocular dominance columns. These experiments indicate that ocular dominance columns are less well segregated in squirrel monkeys than macaques, but they are present. This fact is pertinent to a recent study reporting that ocular dominance columns are absent in normal squirrel monkeys, but induced to form by strabismus (Livingstone, 1996).
Expression of Normal and Mutant Huntingtin in the Developing Brain
Authors: Bhide Pradeep G. , Day Michelle , Sapp Ellen , Schwarz Cordula , Sheth Ami , Kim Johnny , Young Anne B. , Penney John , Golden Jeffrey , Aronin Neil , DiFiglia Marian
Published: April 2018

Huntington’s disease (HD) is caused by a genetic mutation that results in a polyglutamine expansion in huntingtin. The time course of neuronal loss in the HD striatum and other affected brain regions before the onset of symptoms is unknown. To determine the potential influence of huntingtin on brain development, we examined its expression in the developing mouse and in human control and HD brain. By Western blot, huntingtin was detected throughout the adult mouse brain and at all stages of embryonic and postnatal brain development. The protein increased significantly between postnatal day 7 (P7) and P15, which marks a period of active neuronal differentiation and enhanced sensitivity to excitotoxic injury in the rodent striatum. Immunoreactivity was found in neurons throughout the brain and localized mostly to the somatodendritic cytoplasm and to axons in fiber bundles. Staining was variable in different groups of neurons and within the same cell population. In developing brain, huntingtin was limited primarily to neuronal perikarya. Increased immunoreactivity in large neurons followed the gradient of neurogenesis and appeared in the basal forebrain and brainstem by embryonic days 15–17, in regions of cortex by P0–P1, and in the striatum by P7. In human brain at midgestation (19–21 weeks), huntingtin was detected in all regions. The brain of a 10-week-old infant with the expanded HD allele expressed a higher molecular weight mutant form of huntingtin at levels comparable to those of the wild-type protein. Thus, mutant huntingtin is expressed before neuronal maturation is complete. Results suggest that huntingtin has an important constitutive role in neurons during brain development, that heterogeneity in neuronal expression of the protein is developmentally regulated, and that the intraneuronal distribution of huntingtin increases in parallel with neuronal maturation. The presence of mutant huntingtin in the immature HD brain raises the possibility that neurons may be affected during brain development and possibly in the postnatal period when vulnerability to excitotoxic injury is at its peak.
Tau Binds to the Distal Axon Early in Development of Polarity in a Microtubule- and Microfilament-Dependent Manner
Authors: Kempf Martina , Clement Albrecht , Faissner Andreas , Lee Gloria , Brandt Roland
Published: April 2018

Microtubule-associated protein tau is localized to the axonin situand has been implicated in the development of neuronal polarity. Here we report that tau is extracted differentially in cultured hippocampal neurons yielding an axon-specific localization under conditions that keep the integrity of the plasma membrane. The amount of bound tau increases toward the distal axon and is highest at the transition from the axonal shaft to the growth cone. This distribution is significantly different from the distribution of axonal microtubules that are most concentrated at the proximal axon. Distal binding of tau to one process appears early in development of polarity in culture and correlates with the onset of axon formation (day 2 in culture). Binding to the distal axon requires intact microtubules and microfilaments. Distal tau binding does not stabilize microtubules selectively against drug-induced disassembly, because colchicine-induced microtubule depolymerization is highest distally. We conclude that binding of tau to the distal axon follows a complex mechanism, is an early event in the development of polarity, and reproduces the axon-specific localization of tauin situ.
Selective Vulnerability of Mouse CNS Neurons to Latent Infection with a Neuroattenuated Herpes Simplex Virus-1
Authors: Kesari Santosh , Lee Virginia M.-Y. , Brown S. Moira , Trojanowski John Q. , Fraser Nigel W.
Published: April 2018

Herpes simplex viruses that lack ICP34.5 are neuroattenuated and are presently being considered for cancer and gene therapy in the nervous system. Previously, we documented the focal presence of the latency-associated transcripts (LATs) in the hippocampi of immunocompromised mice after intracranial (IC) inoculation of an ICP34.5-deficient virus called strain 1716. To characterize further the biological properties of strain 1716 in the CNS of immunocompetent mice, we determined the extent of viral gene expression in different cell types and regions of the CNS after stereotactic IC inoculation of this virus. At survival times of >30 d after inoculation, we found that (1) infectious virus was not detectable by titration and immunohistochemical studies; (2) neurons harbored virus as demonstrated by the detection of the LATs byin situhybridization (ISH); (3) transcripts expressed during the lytic cycle of infection were not detected by ISH; and (4) subsets of neurons were selectively vulnerable to latent infection, depending on the site of inoculation. These results suggest that the absence of ICP34.5 does not abrogate latent infection of the CNS by strain 1716. Additional studies of strain 1716 in the model system described here will facilitate the elucidation of the mechanisms that regulate the selective vulnerability of CNS cells to latent viral infection and lead to the development of ICP34.5 mutant viruses as therapeutic vectors for CNS diseases.
Reinnervation Accuracy of the Rat Femoral Nerve by Motor and Sensory Neurons
Authors: Madison Roger D. , Archibald Simon J. , Brushart Thomas M.
Published: April 2018

Previous studies in the rat femoral nerve have shown that regeneratingmotorneurons preferentially reinnervate a terminal nerve branch to muscle as opposed to skin, a process that has been called preferential motor reinnervation. However, the ability ofsensoryafferent neurons to accurately reinnervate terminal nerve pathways has been controversial. Within the dorsal root ganglia, sensory neurons projecting to muscle are interspersed with sensory neurons projecting to skin. Thus, anatomical studies assessing the accuracy of sensory neuron regeneration have been hampered by the inability to reliably determine their original innervation status. A sensory neuron that regenerated an axon into a terminal nerve branch to muscle might representeitheran appropriate return of an original sensory afferent to muscle stretch receptorsorthe inappropriate recruitment of a cutaneous sensory afferent that originally innervated skin. The current experiments used a labeling strategy that effectively labels motor and sensory neurons projecting to a terminal nerve branch before experimental manipulation of the parent mixed nerve. Our results confirm previous observations concerning preferential motor reinnervation formotorneurons, and show for the first time anatomical evidence of specificity during regeneration ofsensoryafferent projections to muscle. In addition, the accuracy of sensory afferent regeneration was highly correlated with the accuracy of motor regeneration. This suggests that these two distinct neuronal populations that project to muscle respond in parallel to specific guidance factors during the regeneration process.
Cellular Organization of an Antennal Mechanosensory Pathway in the Cockroach,Periplaneta americana
Authors: Burdohan John A. , Comer Christopher M.
Published: April 2018

Escape responses of cockroaches,Periplaneta americana, can be triggered by wind and mediated by a group of “giant interneurons” that ascend from cercal mechanoreceptors to motor centers. Recently it has been observed that escape also can be triggered by tactile stimulation of the antennae, and it is then independent of the giant interneurons. Here we identify a descending antennal mechanosensory pathway that may account for escape. Cobalt backfills demonstrated that a limited number of cells in the head ganglia have axons that project through all three thoracic ganglia. Comparison with known wind-sensory pathways indicated that wind isnota reliable stimulus for activating descending antennal pathways. However, direct touch stimulation of an antenna reliably evoked short-latency responses in cells with axons in the cervical connectives. Intracellular recording and dye injection revealed members of this pathway, referred to as descending mechanosensory interneurons (DMIs). The two axons of largest diameter in the cervical connectives were found to belong to DMIs, and these large-caliber interneurons were studied in detail. One had a soma in the supraesophageal ganglion, and the other in the subesophageal ganglion. Both had extensive neuritic arborizations at the same level as the soma and axonal arbors in all three thoracic ganglia. Each of these DMIs exhibited short-latency responses to small antennal movements, demonstrated a degree of directional sensitivity, and rapidly conducted impulses to thoracic levels. These cells have properties suggesting that they play a role in a short-latency behavior such as touch-evoked escape.
Correspondence of Escape-Turning Behavior with Activity of Descending Mechanosensory Interneurons in the Cockroach,Periplaneta americana
Authors: Ye Shuping , Comer Christopher M.
Published: April 2018

Two bilaterally paired mechanosensory neurons that respond to antennal touch stimulation recently have been described in the cockroachPeriplaneta americana. Here chronic recordings were used to describe the activity of these interneurons in relation to behavior. Parallel intra/extracellular recording experiments showed that both pairs of previously identified descending mechanosensory interneurons (DMIs) were activated after touch stimulation of the antennae and before initiation of escape. On a trial-by-trial basis, the bilateral pattern of their activity was correlated with sensory input and behavior: when one antenna was touched, the contralateral DMI axons displayed impulses earlier and in greater numbers than their ipsilateral homologs; turns were made toward the side with greater DMI activity, i.e., away from the touched antenna. One parameter of DMI activity (the bilateral difference in number of DMI impulses) was correlated with the angular amplitude of turning. In the absence of touch stimulation, unilateral electrical stimulation of a cervical connective via the chronic electrodes produced turning movements similar to natural escape turning and of appropriate directionality. These results support the hypothesis that neural activity in DMIs is involved in the control of antennal touch-evoked escape, and they provide a basis for a model of DMI specification of the direction of escape turning.
Bcl-2 Sensitivity Differentiates Two Pathways for Motoneuronal Death in thewobblerMutant Mouse
Authors: Coulpier Muriel , Junier Marie-Pierre , Peschanski Marc , Dreyfus Patrick A.
Published: April 2018

The molecular events leading to motoneuronal death are still poorly understood. In mammals, thebcl-2proto-oncogene, which encodes a membrane-associated protein, has been shown to suppress both developmental motoneuronal death and experimental axotomy-induced motoneuronal death. We assessed a potential protective effect of Bcl-2 on pathological motoneuronal death processes in adult rodents. We took advantage of the murine mutantwobbler, which undergoes progressive degeneration of the spinal and brainstem motoneurons. A hybrid carrying both thewobblermutation and the humanbcl-2transgene under the control of the neuron-specific enolase promoter was produced. Although Bcl-2 protected spinal and brainstem motoneurons from developmental death and the postnatal motoneurons of the facial nucleus from axotomy-induced death, the pathological motoneuronal death was not altered in the adult hybrid. These results demonstrate that Bcl-2 sensitivity distinguishes at least two different motoneuronal death pathways in thewobblermutant. They support the hypothesis that experimental and pathological motoneuronal death are dependent on different cellular mechanisms.