RESUMO
Astrocytes release glutamate upon activation of various GPCRs to exert important roles in synaptic functions. However, the molecular mechanism of release has been controversial. Here, we report two kinetically distinct modes of nonvesicular, channel-mediated glutamate release. The fast mode requires activation of G(αi), dissociation of G(ßγ), and subsequent opening of glutamate-permeable, two-pore domain potassium channel TREK-1 through direct interaction between G(ßγ) and N terminus of TREK-1. The slow mode is Ca(2+) dependent and requires G(αq) activation and opening of glutamate-permeable, Ca(2+)-activated anion channel Best1. Ultrastructural analyses demonstrate that TREK-1 is preferentially localized at cell body and processes, whereas Best1 is mostly found in microdomains of astrocytes near synapses. Diffusion modeling predicts that the fast mode can target neuronal mGluR with peak glutamate concentration of 100 µM, whereas slow mode targets neuronal NMDA receptors at around 1 µM. Our results reveal two distinct sources of astrocytic glutamate that can differentially influence neighboring neurons.
Assuntos
Astrócitos/metabolismo , Proteínas do Olho/metabolismo , Ácido Glutâmico/metabolismo , Canais Iônicos/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Sequência de Aminoácidos , Animais , Bestrofinas , Células Cultivadas , Exocitose , Proteínas do Olho/genética , Células HEK293 , Humanos , Canais Iônicos/genética , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Canais de Potássio de Domínios Poros em Tandem/genética , Alinhamento de Sequência , Transdução de SinaisRESUMO
Astrocytes play an essential role in regulating synaptic transmission. This study describes a novel form of modulation of excitatory synaptic transmission in the mouse hippocampus by astrocytic G-protein-coupled receptors (GPCRs). We have previously described astrocytic glutamate release via protease-activated receptor-1 (PAR1) activation, although the regulatory mechanisms for this are complex. Through electrophysiological analysis and modeling, we discovered that PAR1 activation consistently increases the concentration and duration of glutamate in the synaptic cleft. This effect was not due to changes in the presynaptic glutamate release or alteration in glutamate transporter expression. However, blocking group II metabotropic glutamate receptors (mGluR2/3) abolished PAR1-mediated regulation of synaptic glutamate concentration, suggesting a role for this GPCR in mediating the effects of PAR1 activation on glutamate release. Furthermore, activation of mGluR2/3 causes glutamate release through the TREK-1 channel in hippocampal astrocytes. These data show that astrocytic GPCRs engage in a novel regulatory mechanism to shape the time course of synaptically-released glutamate in excitatory synapses of the hippocampus.
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Astrócitos , Região CA1 Hipocampal , Ácido Glutâmico , Camundongos Endogâmicos C57BL , Receptor PAR-1 , Receptores de Glutamato Metabotrópico , Sinapses , Animais , Receptores de Glutamato Metabotrópico/metabolismo , Astrócitos/metabolismo , Ácido Glutâmico/metabolismo , Sinapses/metabolismo , Região CA1 Hipocampal/metabolismo , Receptor PAR-1/metabolismo , Camundongos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Masculino , Transmissão Sináptica/fisiologia , Transmissão Sináptica/efeitos dos fármacos , Canais de Potássio de Domínios Poros em Tandem/metabolismoRESUMO
µ-opioid receptor (MOR) is a class of opioid receptors that is critical for analgesia, reward, and euphoria. MOR is distributed in various brain regions, including the hippocampus, where traditionally, it is believed to be localized mainly at the presynaptic terminals of the GABAergic inhibitory interneurons to exert a strong disinhibitory effect on excitatory pyramidal neurons. However, recent intensive research has uncovered the existence of MOR in hippocampal astrocytes, shedding light on how astrocytic MOR participates in opioid signaling via glia-neuron interaction in the hippocampus. Activation of astrocytic MOR has shown to cause glutamate release from hippocampal astrocytes and increase the excitability of presynaptic axon fibers to enhance the release of glutamate at the Schaffer Collateral-CA1 synapses, thereby, intensifying the synaptic strength and plasticity. This novel mechanism involving astrocytic MOR has been shown to participate in hippocampus-dependent conditioned place preference. Furthermore, the signaling of hippocampal MOR, whose action is sexually dimorphic, is engaged in adult neurogenesis, seizure, and stress-induced memory impairment. In this review, we focus on the two profoundly different hippocampal opioid signaling pathways through either GABAergic interneuronal or astrocytic MOR. We further compare and contrast their molecular and cellular mechanisms and their possible roles in opioid-associated conditioned place preference and other hippocampus-dependent behaviors.
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Astrócitos/metabolismo , Ácido Glutâmico/metabolismo , Hipocampo/fisiologia , Interneurônios/metabolismo , Receptores Opioides mu/metabolismo , Transdução de Sinais , Animais , Astrócitos/citologia , Ácido Glutâmico/análise , Hipocampo/citologia , Humanos , Interneurônios/citologia , Receptores Opioides mu/análise , Transmissão SinápticaRESUMO
The postsynaptic density (PSD)-95-like, disk-large (DLG) membrane-associated guanylate kinase (PSD/DLG-MAGUK) family of proteins scaffold α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) complexes to the postsynaptic compartment and are postulated to orchestrate activity-dependent modulation of synaptic AMPAR functions. SAP102 is a key member of this family, present from early development, before PSD-95 and PSD-93, and throughout life. Here we investigate the role of SAP102 in synaptic transmission using a cell-restricted molecular replacement strategy, where SAP102 is expressed against the background of acute knockdown of endogenous PSD-95. We show that SAP102 rescues the decrease of AMPAR-mediated evoked excitatory postsynaptic currents (AMPAR eEPSCs) and AMPAR miniature EPSC (AMPAR mEPSC) frequency caused by acute knockdown of PSD-95. Further analysis of the mini events revealed that PSD-95-to-SAP102 replacement but not direct manipulation of PSD-95 increases the AMPAR mEPSC decay time. SAP102-mediated rescue of AMPAR eEPSCs requires AMPAR auxiliary subunit cornichon-2, whereas cornichon-2 knockdown did not affect PSD-95-mediated regulation of AMPAR eEPSC. Combining these observations, our data elucidate that PSD-95 and SAP102 differentially influence basic synaptic properties and synaptic current kinetics potentially via different AMPAR auxiliary subunits. NEW & NOTEWORTHY Synaptic scaffold proteins postsynaptic density (PSD)-95-like, disk-large (DLG) membrane-associated guanylate kinase (PSD-MAGUKs) regulate synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) function. However, the functional diversity among different PSD-MAGUKs remains to be categorized. We show that distinct from PSD-95, SAP102 increase the AMPAR synaptic current decay time, and the effect of SAP102 on synaptic AMPAR function requires the AMPAR auxiliary subunit cornichon-2. Our data suggest that PSD-MAGUKs target and modulate different AMPAR complexes to exert specific experience-dependent modification of the excitatory circuit.
Assuntos
Potenciais Pós-Sinápticos Excitadores , Neuropeptídeos/metabolismo , Receptores de AMPA/metabolismo , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/metabolismo , Região CA1 Hipocampal/fisiologia , Células Cultivadas , Proteína 4 Homóloga a Disks-Large/metabolismo , Potenciais Pós-Sinápticos em Miniatura , Células Piramidais/metabolismo , Células Piramidais/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
PURPOSE: We determined the prognostic impact of a synchronous second primary malignancy on overall survival in patients with metastatic prostate cancer. Identifying features that stratify the risk of overall survival is critical for judiciously applying definitive therapy. MATERIALS AND METHODS: We retrospectively analyzed the records of 582 consecutive patients with prostate cancer diagnosed with metastasis between May 7, 1998 and August 27, 2011. Patient age, body mass index, ECOG performance status, Charlson comorbidity index, prostate specific antigen, T and N stages, Gleason and ASA® scores, progression to castration resistant prostate cancer, prior local treatments and synchronous second primary malignancies at metastasis were assessed. A synchronous second primary malignancy was defined as a cytologically or histologically proven solid malignancy. Cox proportional hazards regression analysis was done to estimate overall survival by second primary type and evaluate predictive variables. RESULTS: A total of 164 patients (28.1%) had a synchronous second primary malignancy, of which colorectal (9.1%), stomach (7.3%) and lung (7.1%) cancers were the most prevalent types. During a median followup of 34.1 months patients without a synchronous second primary malignancy had a significantly higher overall survival rate than those with lung or stomach cancer. However, men without a second malignancy had outcomes comparable to those in men with colorectal cancer. Clinical stage T4 or greater, ASA score 1 or greater and lung or stomach cancer were independent predictors of overall mortality. CONCLUSIONS: A substantial proportion of patients with metastatic prostate cancer present with a synchronous second primary malignancy. Definitive therapy targeting prostate cancer may confer a limited survival benefit in patients with synchronous lung or stomach cancer.
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Segunda Neoplasia Primária/mortalidade , Neoplasias da Próstata/mortalidade , Neoplasias da Próstata/patologia , Humanos , Masculino , Metástase Neoplásica , Prognóstico , Estudos Retrospectivos , Risco , Taxa de SobrevidaRESUMO
BACKGROUND: Platinum-based systemic chemotherapy is the treatment of choice for patients with advanced urothelial carcinoma (UC). Although no chemotherapeutic regimen is established as a second-line therapy, recent studies reported that methotrexate, vinblastine, Adriamycin and cisplatin (MVAC) elicited a significant response in patients who failed gemcitabine and platinum (GP) chemotherapy. We investigated the clinical factors useful for predicting a favourable response to MVAC in UC patients who failed GP. METHODS: Forty-five patients with advanced UC who received second-line MVAC chemotherapy after failure with first-line GP chemotherapy were enrolled in this study. Univariate and multivariate analyses based on Cox's regression were performed to identify independent prognostic factors for progression-free survival (PFS) after second-line MVAC chemotherapy. RESULTS: The median follow-up period after the first MVAC administration was 10.0 months. The median PFS and overall survival (OS) were 6.5 months (95% confidence interval [CI]: 5.1-7.9) and 14.5 months (95% CI, 7.4-21.4), respectively. The overall response rate was 57.8%. The response to first-line GP chemotherapy (hazard ratio [HR], 2.500; p = 0.012) and patient age (HR, 1.047; p = 0.033) were predictors of PFS after MVAC chemotherapy. CONCLUSIONS: The response to first-line GP chemotherapy and age were independent predictors of PFS in patients who received second-line MVAC chemotherapy. This report is the first to describe independent predictors of PFS after MVAC chemotherapy.
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Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Desoxicitidina/análogos & derivados , Platina/administração & dosagem , Neoplasias Urológicas/diagnóstico , Neoplasias Urológicas/tratamento farmacológico , Urotélio/patologia , Idoso , Cisplatino/administração & dosagem , Desoxicitidina/administração & dosagem , Intervalo Livre de Doença , Doxorrubicina/administração & dosagem , Feminino , Seguimentos , Humanos , Masculino , Metotrexato/administração & dosagem , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Falha de Tratamento , Vimblastina/administração & dosagem , GencitabinaRESUMO
BACKGROUND: Epigenetic modifications play a critical role in the regulation of all DNA-based processes, such as transcription, repair, and replication. Inappropriate histone modifications can result in dysregulation of cell growth, leading to neoplastic transformation and cell death. Renal tumors have been shown to have a higher global methylation percentage and reduced histone acetylation. Preclinical models have revealed that histone gene modifiers and epigenetic alterations play important roles in renal cell carcinoma (RCC) tumorigenesis. Recently, a novel HDAC inhibitor, N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), has been introduced as an example of a new class of anti-cancer agents. The anti-cancer activity of HNHA and the underlying mechanisms of action remain to be clarified. METHODS: The MTS assay using a panel of RCC cells was used to evaluate the anti-proliferative effects of HNHA. The established HDAC inhibitors, SAHA and TSA, were used for comparison. Western blotting analysis was performed to investigate the acetylation of histone H3 and the expression of apoptotic markers in vitro and in vivo. Subcellular fractionation was performed to evaluate expression of Bax and cytochrome c in the cytosol and mitochondria, and also translocation of cytochrome c from the cytoplasm to the nucleus. A confocal microscopic evaluation was performed to confirm inhibition of cell proliferation, induction of apoptosis, and the nuclear translocation of cytochrome c in RCC cells. RESULTS: In this study, we investigated the apoptosis-inducing activity of HNHA in cultured kidney cancer cells. Apoptosis in the HNHA-treated group was induced significantly, with marked caspase activation and Bcl-2 suppression in RCC cells in vitro and in vivo. HNHA treatment caused cytochrome c release from mitochondria, which was mediated by increased Bax expression and caspase activation. HNHA also induced nuclear translocation of cytochrome c, suggesting that HNHA can induce caspase-independent nuclear apoptosis in RCC cells. An in vivo study showed that HNHA had greater anti-tumor and pro-apoptotic effects on RCC xenografts than the established HDAC inhibitors. CONCLUSIONS: HNHA has more potent anti-tumor activity than established HDAC inhibitors. Its activities are mediated by caspase-dependent and cytochrome-c-mediated apoptosis in RCC cells. These results suggest that HNHA may offer a new therapeutic approach to RCC.
Assuntos
Antineoplásicos/uso terapêutico , Apoptose/efeitos dos fármacos , Carcinoma de Células Renais/tratamento farmacológico , Citocromos c/metabolismo , Inibidores de Histona Desacetilases/uso terapêutico , Ácidos Hidroxâmicos/uso terapêutico , Neoplasias Renais/tratamento farmacológico , Naftalenos/uso terapêutico , Acetilação , Animais , Western Blotting/métodos , Carcinoma de Células Renais/enzimologia , Carcinoma de Células Renais/patologia , Caspases/metabolismo , Fracionamento Celular/métodos , Histonas/metabolismo , Humanos , Proteínas I-kappa B/metabolismo , Marcação In Situ das Extremidades Cortadas , Neoplasias Renais/enzimologia , Neoplasias Renais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Mitocôndrias/enzimologia , Transplante de Neoplasias , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Células Tumorais Cultivadas , Proteína X Associada a bcl-2/metabolismoRESUMO
GABA is the major inhibitory transmitter in the brain and is released not only from a subset of neurons but also from glia. Although neuronal GABA is well known to be synthesized by glutamic acid decarboxylase (GAD), the source of glial GABA is unknown. After estimating the concentration of GABA in Bergmann glia to be around 5-10 mM by immunogold electron microscopy, we demonstrate that GABA production in glia requires MAOB, a key enzyme in the putrescine degradation pathway. In cultured cerebellar glia, both Ca(2+)-induced and tonic GABA release are significantly reduced by both gene silencing of MAOB and the MAOB inhibitor selegiline. In the cerebellum and striatum of adult mice, general gene silencing, knock out of MAOB or selegiline treatment resulted in elimination of tonic GABA currents recorded from granule neurons and medium spiny neurons. Glial-specific rescue of MAOB resulted in complete rescue of tonic GABA currents. Our results identify MAOB as a key synthesizing enzyme of glial GABA, which is released via bestrophin 1 (Best1) channel to mediate tonic inhibition in the brain.
Assuntos
Monoaminoxidase/metabolismo , Neuroglia/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Cerebelo/citologia , Cerebelo/metabolismo , Corpo Estriado/citologia , Corpo Estriado/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Monoaminoxidase/genética , Inibição Neural , Neuroglia/fisiologiaRESUMO
New psychoactive substances (NPSs) are compounds designed to mimic illegal recreational drugs. In particular, there are difficulties in legal restrictions because there is no fast NPS detection method to suppress the initial spread of NPS with criminal records; thus, they expose the public to serious health threats, including toxicity and dependence. However, the effects of NPSs on the brain and the related cellular mechanisms are well unknown. One of the recently emerging drugs is 4-ethylamphetamine-NBOMe (4-EA-NBOMe), a member of the 2 C phenylalanine family with a similar structure to methamphetamine (methA). In this study, we tested the effect of methA analogs on the glutamatergic synaptic transmission on primary cultured cortical neurons of SpragueDawley (SD) rats and C57BL/6 mice, and also layer 2/3 pyramidal neurons of the medial prefrontal cortex (mPFC) of C57BL/6 mice. We found that acute treatment with 4-EA-NBOMe inhibits spontaneous excitatory postsynaptic currents (EPSCs) and that withdrawal after chronic inhibition by 4-EA-NBOMe augments glutamatergic synaptic transmission. These modifications of synaptic responses are mediated by 5-HT1A receptors. These findings suggest that 4-EA-NBOMe directly affects the central nervous system by changing the efficacy of glutamatergic synaptic transmission.
Assuntos
Metanfetamina , Serotonina , Camundongos , Ratos , Animais , Serotonina/farmacologia , Anfetamina , Camundongos Endogâmicos C57BL , Células Piramidais/fisiologia , Neurônios , Transmissão SinápticaRESUMO
BACKGROUND: Reactive astrogliosis is a hallmark of various brain pathologies, including neurodegenerative diseases and glioblastomas. However, the specific intermediate metabolites contributing to reactive astrogliosis remain unknown. This study investigated how glioblastomas induce reactive astrogliosis in the neighboring microenvironment and explores 11C-acetate PET as an imaging technique for detecting reactive astrogliosis. METHODS: Through in vitro, mouse models, and human tissue experiments, we examined the association between elevated 11C-acetate uptake and reactive astrogliosis in gliomas. We explored acetate from glioblastoma cells, which triggers reactive astrogliosis in neighboring astrocytes by upregulating MAO-B and MCT1 expression. We evaluated the presence of cancer stem cells in the reactive astrogliosis region of glioblastomas and assessed the correlation between the volume of 11C-acetate uptake beyond MRI and prognosis. RESULTS: Elevated 11C-acetate uptake is associated with reactive astrogliosis and astrocytic MCT1 in the periphery of glioblastomas in human tissues and mouse models. Glioblastoma cells exhibit increased acetate production as a result of glucose metabolism, with subsequent secretion of acetate. Acetate derived from glioblastoma cells induces reactive astrogliosis in neighboring astrocytes by increasing the expression of MAO-B and MCT1. We found cancer stem cells within the reactive astrogliosis at the tumor periphery. Consequently, a larger volume of 11C-acetate uptake beyond contrast-enhanced MRI was associated with worse prognosis. CONCLUSION: Our results highlight the role of acetate derived from glioblastoma cells in inducing reactive astrogliosis and underscore the potential value of 11C-acetate PET as an imaging technique for detecting reactive astrogliosis, offering important implications for the diagnosis and treatment of glioblastomas.
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Glioblastoma (GBM) is the most common and malignant form of primary brain tumor with a median survival time of 14-16 months in GBM patients. Surgical treatment with chemotherapy and radiotherapy may help increase survival by removing GBM from the brain. However, complete surgical resection to eliminate GBM is almost impossible due to its high invasiveness. When GBM cells migrate to the brain, they interact with various cells, including astrocytes, neurons, endothelial cells, and the extracellular matrix (ECM). They can also make their cell body shrink to infiltrate into narrow spaces in the brain; thereby, they can invade regions of the brain and escape from surgery. Brain tumor cells create an appropriate microenvironment for migration and invasion by modifying and degrading the ECM. During those processes, the Ca2+ signaling pathway and other signaling cascades mediated by various ion channels contribute mainly to gene expression, motility, and invasion of GBM cells. Furthermore, GBM cells release glutamate, affecting migration via activation of ionotropic glutamate receptors in an autocrine manner. This review focuses on the cellular mechanisms of glioblastoma invasion and motility related to ECM, Ca2+ signaling, and glutamate. Finally, we discuss possible therapeutic interventions to inhibit invasion by GBM cells.
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Central neurocytoma (CN) has been known as a benign neuronal tumor. In rare cases, CN undergoes malignant transformation to glioblastomas (GBM). Here we examined its cellular origin by characterizing differentiation potential and gene expression of CN-spheroids. First, we demonstrate that both CN tissue and cultured primary cells recapitulate the hierarchal cellular composition of subventricular zone (SVZ), which is comprised of neural stem cells (NSCs), transit amplifying progenitors (TAPs), and neuroblasts. We then derived spheroids from CN which displayed EGFR+/ MASH+ TAP and BLBP+ radial glial cell (RGC) characteristic, and mitotic neurogenesis and gliogenesis by single spheroids were observed with cycling multipotential cells. CN-spheroids expressed increased levels of pluripotency and tumor stem cell genes such as KLF4 and TPD5L1, when compared to their differentiated cells and human NSCs. Importantly, Gene Set Enrichment Analysis showed that gene sets of GBM-Spheroids, EGFR Signaling, and Packaging of Telomere Ends are enriched in CN-spheroids in comparison with their differentiated cells. We speculate that CN tumor stem cells have TAP and RGC characteristics, and upregulation of EGFR signaling as well as downregulation of eph-ephrin signaling have critical roles in tumorigenesis of CN. And their ephemeral nature of TAPs destined to neuroblasts, might reflect benign nature of CN.
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In mammalian brain, neurons and astrocytes are reported to express various chloride and anion channels, but the evidence for functional expression of Ca(2+)-activated anion channel (CAAC) and its molecular identity have been lacking. Here we report electrophysiological evidence for the CAAC expression and its molecular identity by mouse Bestrophin 1 (mBest1) in astrocytes of the mouse brain. Using Ca(2+) imaging and perforated-patch-clamp analysis, we demonstrate that astrocytes displayed an inward current at holding potential of -70 mV that was dependent on an increase in intracellular Ca(2+) after G(alphaq)-coupled receptor activation. This current was mediated mostly by anions and was sensitive to well known anion channel blockers such as niflumic acid, 5-nitro-2(3-phenylpropylamino)-benzoic acid, and flufenamic acid. To find the molecular identity of the anion channel responsible for the CAAC current, we analyzed the expression of candidate genes and found that the mRNA for mouse mBest1 is predominantly expressed in acutely dissociated or cultured astrocytes. Whole-cell patch-clamp analysis using HEK293T cells heterologously expressing full-length mBest1 showed a Ca(2+)-dependent current mediated by mBest1, with a complete impairment of the current by a putative pore mutation, W93C. Furthermore, mBest1-mediated CAAC from cultured astrocytes was significantly reduced by expression of mBest1-specific short hairpin RNA (shRNA), suggesting that the CAAC is mediated by a channel encoded by mBest1. Finally, hippocampal CA1 astrocytes in hippocampal slice also showed mBest1-mediated CAAC because it was inhibited by mBest1-specific shRNA. Collectively, these data provide molecular evidence that the mBest1 channel is responsible for CAAC function in astrocytes.
Assuntos
Astrócitos/fisiologia , Cálcio/metabolismo , Canais de Cloreto/fisiologia , Proteínas do Olho/metabolismo , Hipocampo/citologia , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/farmacologia , Análise de Variância , Animais , Animais Recém-Nascidos , Bestrofinas , Bradicinina/farmacologia , Células Cultivadas , Córtex Cerebral/citologia , Quelantes/farmacologia , Canais de Cloreto/genética , Dinoprostona/farmacologia , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Estimulação Elétrica/métodos , Inibidores Enzimáticos/farmacologia , Estrenos/farmacologia , Regulação da Expressão Gênica/genética , Humanos , Técnicas In Vitro , Canais Iônicos , Lisofosfolipídeos/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Oligopeptídeos/farmacologia , Técnicas de Patch-Clamp , Pirrolidinonas/farmacologia , RNA Interferente Pequeno/genética , Tapsigargina/farmacologia , Tionucleotídeos/farmacologia , Transfecção/métodosRESUMO
Climbing fibers from the inferior olive make strong excitatory synapses onto cerebellar Purkinje cell (PC) dendrites and trigger distinctive responses known as complex spikes. We found that, in awake mice, a complex spike in one PC suppressed conventional simple spikes in neighboring PCs for several milliseconds. This involved a new ephaptic coupling, in which an excitatory synapse generated large negative extracellular signals that nonsynaptically inhibited neighboring PCs. The distance dependence of complex spike-simple spike ephaptic signaling, combined with the known CF divergence, allowed a single inferior olive neuron to influence the output of the cerebellum by synchronously suppressing the firing of potentially over 100 PCs. Optogenetic studies in vivo and dynamic clamp studies in slice indicated that such brief PC suppression, as a result of either ephaptic signaling or other mechanisms, could effectively promote firing in neurons in the deep cerebellar nuclei with remarkable speed and precision.
Assuntos
Potenciais de Ação , Células de Purkinje/fisiologia , Sinapses/patologia , Animais , Axônios/fisiologia , Dendritos/fisiologia , Fenômenos Eletrofisiológicos , Feminino , Masculino , Camundongos Endogâmicos C57BLRESUMO
There is a growing interest in window air filters to protect indoor air quality from ultrafine particulate matter (PM) in outdoor air. The filters for this purpose must achieve high filtering efficiency without compromising the original functions of the window, such as high air permeability and visibility. Several filters meeting these requirements have been developed and demonstrate a high PM2.5 filtering efficiency. However, these filters are installed outside the window or on the window screen guard, thereby requiring high levels of ultraviolet (UV), chemical, and thermal resistance. These requirements have been overlooked so far. In this study, we examine the fabrication and performance of a polybenzimidazole-benzophenone (PBI-BP) composite nanofiber air filter that demonstrates superb UV resistance and chemical and thermal durability. Because of the UV absorbance of the BP in the nanofibers, the filter membrane is robust even under prolonged UV exposure, which is essential for filters for this purpose. The filter membrane is not damaged even after treatment in strong acids or annealing at high temperature up to 400 °C. Thus, the PBI-BP composite filter is suitable for practical application in window air filters and can be adapted to develop filters used under other harsh environments.
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PURPOSE: We evaluated the clinical significance of lymphovascular invasion in transurethral resection of bladder tumor specimens in patients with newly diagnosed T1 urothelial carcinoma of the bladder. MATERIALS AND METHODS: Enrolled in the study were 118 patients with newly diagnosed T1 urothelial carcinoma of the bladder who underwent transurethral resection of bladder tumor between 2001 and 2007. Patient records were retrieved from a prospectively maintained bladder cancer database. We evaluated the correlation between lymphovascular invasion and other clinicopathological features, and the impact of lymphovascular invasion on disease recurrence, disease progression and metastasis. RESULTS: Lymphovascular invasion was histologically confirmed in 33 patients (28.0%). While lymphovascular invasion correlated with tumor grade (p = 0.002), it was not associated with gender, age, bladder tumor history, tumor size, multiplicity or concomitant carcinoma in situ. Recurrence, progression and metastasis developed in 45 (38.1%), 19 (16.1%) and 10 patients (8.5%), respectively. Univariate analysis showed that lymphovascular invasion was marginally associated with recurrence and significantly associated with progression (p = 0.011) and metastasis (p = 0.019). Multivariate Cox proportional hazards analysis revealed that recurrence was significantly associated with lymphovascular invasion (p = 0.029), and with bladder tumor history (p <0.001), tumor size (p = 0.031) and multiplicity (p = 0.043). Lymphovascular invasion was the only independent prognostic factor associated with progression (p = 0.016). CONCLUSIONS: In patients with newly diagnosed T1 urothelial carcinoma of the bladder lymphovascular invasion in transurethral resection of bladder tumor specimens predicts disease progression and metastasis.
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Carcinoma de Células de Transição/secundário , Carcinoma de Células de Transição/cirurgia , Cistectomia/métodos , Neoplasias da Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/cirurgia , Neoplasias Vasculares/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Progressão da Doença , Feminino , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia/patologia , Prognóstico , UretraRESUMO
Ultrafine particulate matters (PMs) are an imminent threat to the human respiratory system, as their sizes are comparable to and even smaller than human tissues. To cope with this situation, researchers have developed and commercialized various personal dust proof masks. However, because of the relatively thick filter membrane to guarantee filtering efficiency, a huge pressure drop across the active filter layer is inevitable and breathing through it becomes uncomfortable. In this work, we investigated the performance of electrospun polybenzimidazole (PBI) nanofiber membrane filters that can potentially be used for dust proof masks or other high-performance filters. Thanks to its high dipole moment (6.12) as confirmed by density functional theory (DFT) calculation, the surface potential of the PBI nanofiber air filter, measured by KPFM, was higher than that of other commercially available mask filters. The filter developed in this work provides high PM filtering efficiency of â¼98.5% at much reduced pressure drop (130 Pa) in comparison to those used in commercially available masks (386 Pa) with similar filtering efficiencies. Consequently, an approximately 3-fold higher quality factor (â¼0.032), evaluated for PM2.5, in comparison to that of commercial ones (â¼0.011) was achieved by using PBI nanofiber. Furthermore, we developed a cleaning method effective for the filter contaminated by both inorganic and organic PMs. Even after several cycles of cleaning, the PBI filter membrane demonstrated negligible damage and retained its original performance because of its mechanical, thermal, and chemical durability.
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Benzimidazóis/química , Nanofibras/química , Material Particulado/química , Filtros de Ar , Teoria da Densidade Funcional , Filtração/métodos , Humanos , Tamanho da PartículaRESUMO
The underlying mechanisms of how positive emotional valence (e.g., pleasure) causes preference of an associated context is poorly understood. Here, we show that activation of astrocytic µ-opioid receptor (MOR) drives conditioned place preference (CPP) by means of specific modulation of astrocytic MOR, an exemplar endogenous Gi protein-coupled receptor (Gi-GPCR), in the CA1 hippocampus. Long-term potentiation (LTP) induced by a subthreshold stimulation with the activation of astrocytic MOR at the Schaffer collateral pathway accounts for the memory acquisition to induce CPP. This astrocytic MOR-mediated LTP induction is dependent on astrocytic glutamate released upon activation of the astrocytic MOR and the consequent activation of the presynaptic mGluR1. The astrocytic MOR-dependent LTP and CPP were recapitulated by a chemogenetic activation of astrocyte-specifically expressed Gi-DREADD hM4Di. Our study reveals that the transduction of inhibitory Gi-signaling into augmented excitatory synaptic transmission through astrocytic glutamate is critical for the acquisition of contextual memory for CPP.
Assuntos
Astrócitos/metabolismo , Região CA1 Hipocampal/metabolismo , Memória , Receptores Opioides mu/metabolismo , Animais , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Camundongos , Camundongos Knockout , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismo , Receptores Opioides mu/genéticaRESUMO
OBJECTIVE: Of the many surgical options available for ureteral reconstruction during surgery for non-urologic pelvic malignancies, the efficacy of transureteroureterostomy (TUU) was investigated. METHODS: Ureteral reconstruction was dichotomized as follows: group 1, end-to-end ureteroureterostomy and ureteroneocystostomy (UNC) with or without a psoas hitch; and group 2, TUU. TUU was preferably performed when partial bladder invasion was suspected or patients had undergone prior surgery or radiotherapy. Groups 1 and 2 included 17 and 28 patients, respectively. These patients were consecutively enrolled and analyzed with respect to complications and clinical outcomes. RESULTS: Of the complications that followed TUU, persistent hydronephrosis and a transient urine leak were detected in one patient each. No differences in complication rates were observed between the two groups with respect to hydronephrosis, azotemia, urine leak, and acute pyelonephritis. Patients who had a UNC with a psoas hitch tended to have more frequent voiding dysfunction postoperatively than those who had a TUU. CONCLUSIONS: TUU is a feasible technique for ureteral reconstruction when multivisceral resection, including the ureter, is performed during surgery for non-urologic pelvic malignancies. TUU could be a preferred method in patients requiring partial cystectomy or in those that have undergone prior surgery or radiotherapy.
Assuntos
Neoplasias Pélvicas/cirurgia , Procedimentos de Cirurgia Plástica/métodos , Ureter/cirurgia , Ureterostomia/métodos , Adulto , Idoso , Cistectomia , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Hidronefrose/etiologia , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia/mortalidade , Nefrectomia , Procedimentos de Cirurgia Plástica/efeitos adversos , Taxa de Sobrevida , Obstrução Ureteral/etiologiaRESUMO
INTRODUCTION: Frequent mutations or deletions of PTEN (phosphatase and tensin homolog deleted on chromosome 10) are reported in bladder cancer, while there are few studies which evaluated PTEN as a clinical prognostic parameter of superficial bladder cancer. We prospectively evaluated PTEN expression in patients with superficial bladder cancer by immunohistochemical staining and defined the value of PTEN mutations in predicting tumor behavior of superficial bladder cancer. MATERIALS AND METHODS: A total of 190 patients were enrolled in this study. All of the patients underwent transurethral resection of bladder tumor and had superficial tumors. All pathologic materials used in this study were obtained from transurethral resection of bladder tumor. Immunohistochemical stainings were performed. The immunohistochemical staining intensity was judged to be either normal or reduced compared with the PTEN protein expression of positive and negative controls. Disappearance of more than 50% stained cytoplasmic granules was defined as reduced PTEN expression. RESULTS: The alteration of PTEN expression was significantly different according to tumor stage and grade (p = 0.03, p = 0.048), especially high in carcinoma in situ. However, PTEN expression was not significantly correlated with disease recurrence, progression and recurrence- or progression-free survival. CONCLUSIONS: Reduced PTEN expression relates to aggressiveness of bladder tumors but seems not to have enough specificity for clinical use in the management of superficial bladder cancer.