RESUMEN
Developmental myelination is a protracted process in the mammalian brain1. One theory for why oligodendrocytes mature so slowly posits that myelination may stabilize neuronal circuits and temper neuronal plasticity as animals age2-4. We tested this theory in the visual cortex, which has a well-defined critical period for experience-dependent neuronal plasticity5. During adolescence, visual experience modulated the rate of oligodendrocyte maturation in visual cortex. To determine whether oligodendrocyte maturation in turn regulates neuronal plasticity, we genetically blocked oligodendrocyte differentiation and myelination in adolescent mice. In adult mice lacking adolescent oligodendrogenesis, a brief period of monocular deprivation led to a significant decrease in visual cortex responses to the deprived eye, reminiscent of the plasticity normally restricted to adolescence. This enhanced functional plasticity was accompanied by a greater turnover of dendritic spines and coordinated reductions in spine size following deprivation. Furthermore, inhibitory synaptic transmission, which gates experience-dependent plasticity at the circuit level, was diminished in the absence of adolescent oligodendrogenesis. These results establish a critical role for oligodendrocytes in shaping the maturation and stabilization of cortical circuits and support the concept of developmental myelination acting as a functional brake on neuronal plasticity.
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Envejecimiento , Vaina de Mielina , Plasticidad Neuronal , Oligodendroglía , Corteza Visual , Animales , Femenino , Masculino , Ratones , Envejecimiento/fisiología , Diferenciación Celular/genética , Espinas Dendríticas/fisiología , Espinas Dendríticas/metabolismo , Vaina de Mielina/metabolismo , Plasticidad Neuronal/fisiología , Oligodendroglía/citología , Oligodendroglía/metabolismo , Oligodendroglía/fisiología , Privación Sensorial/fisiología , Transmisión Sináptica/fisiología , Visión Monocular/fisiología , Corteza Visual/citología , Corteza Visual/fisiología , Corteza Visual/crecimiento & desarrolloRESUMEN
We have previously shown that recovery of visual responses to a deprived eye during the critical period in mouse primary visual cortex requires phosphorylation of the TrkB receptor for BDNF [M. Kaneko, J. L. Hanover, P. M. England, M. P. Stryker, Nat. Neurosci. 11, 497-504 (2008)]. We have now studied the temporal relationship between the production of mature BDNF and the recovery of visual responses under several different conditions. Visual cortical responses to an eye whose vision has been occluded for several days during the critical period and is then re-opened recover rapidly during binocular vision or much more slowly following reverse occlusion, when the previously intact fellow eye is occluded in a model of "patch therapy" for amblyopia. The time to recovery of visual responses differed by more than 18 h between these two procedures, but in each, the production of mature BDNF preceded the physiological recovery. These findings suggest that a spurt of BDNF production is permissive for the growth of connections serving the deprived eye to restore visual responses. Attenuation of recovery of deprived-eye responses by interference with TrkB receptor activation or reduction of BDNF production by interference with homeostatic synaptic scaling had effects consistent with this suggestion.
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Ambliopía , Corteza Visual , Ratones , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Receptor trkB/metabolismo , Corteza Visual/fisiología , Visión Ocular , Privación Sensorial/fisiología , Plasticidad Neuronal/fisiologíaRESUMEN
When adult mice are repeatedly exposed to a particular visual stimulus for as little as 1 h per day for several days while their visual cortex (V1) is in the high-gain state produced by locomotion, that specific stimulus elicits much stronger responses in V1 neurons for the following several weeks, even when measured in anesthetized animals. Such stimulus-specific enhancement (SSE) is not seen if locomotion is prevented. The effect of locomotion on cortical responses is mediated by vasoactive intestinal peptide (VIP) positive interneurons, which can release both the peptide and the inhibitory neurotransmitter GABA. Previous studies have examined the role of VIP-ergic interneurons, but none have distinguished the individual roles of peptide from GABA release. Here, we used genetic ablation to determine which of those molecules secreted by VIP-ergic neurons is responsible for SSE. SSE was not impaired by VIP deletion but was prevented by compromising release of GABA from VIP cells. This finding suggests that SSE may result from Hebbian mechanisms that remain present in adult V1.NEW & NOTEWORTHY Many neurons package and release a peptide along with a conventional neurotransmitter. The conventional view is that such peptides exert late, slow effects on plasticity. We studied a form of cortical plasticity that depends on the activity of neurons that express both vasoactive intestinal peptide (VIP) and the inhibitory neurotransmitter GABA. GABA release accounted for their action on plasticity, with no effect of deleting the peptide on this phenomenon.
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Interneuronas , Péptido Intestinal Vasoactivo , Corteza Visual , Ácido gamma-Aminobutírico , Animales , Péptido Intestinal Vasoactivo/metabolismo , Interneuronas/metabolismo , Interneuronas/fisiología , Ácido gamma-Aminobutírico/metabolismo , Ratones , Corteza Visual/metabolismo , Corteza Visual/fisiología , Ratones Endogámicos C57BL , Masculino , Estimulación Luminosa , FemeninoRESUMEN
BACKGROUND: For simultaneous prediction of phenotypic drug susceptibility test (pDST) for multiple anti-tuberculosis drugs, the whole genome sequencing (WGS) data can be analyzed using either catalogue-based approach, wherein one causative mutation suggests resistance, (e.g., WHO catalog) or non-catalogue-based approach using complicated algorithm (e.g., TB-profiler, machine learning). The aim was to estimate the predictive ability of WGS-based tests with pDST as the reference, and to compare the two approaches. METHODS: Following the systematic literature search, the diagnostic test accuracies for 14 drugs were pooled using a random-effect bivariate model. RESULTS: Out of 779 articles, 44 articles with 16,821 specimens for meta-analysis and 13 articles not for meta-analysis were adopted. The areas under summary receiver operating characteristic curve suggested "excellent" (0.97-1.00) for 2 drugs (isoniazid 0.975, rifampicin 0.975), "very good" (0.93-0.97) for 8 drugs (pyrazinamide 0.946, streptomycin 0.952, amikacin 0.968, kanamycin 0.963, capreomycin 0.965, para-aminosalicylic acid 0.959, levofloxacin 0.960, ofloxacin 0.958), and "good" (0.75-0.93) for 4 drugs (ethambutol 0.926, moxifloxacin 0.896, ethionamide 0.878, prothionamide 0.908). The non-catalogue-based and catalogue-based approaches had similar ability for all drugs. CONCLUSION: WGS accurately identifies isoniazid and rifampicin resistance. For most drugs, positive WGS results reliably predict pDST positive. The two approaches had similar ability.
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The maturation of GABAergic inhibitory circuits is necessary for the onset of the critical period for ocular dominance plasticity (ODP) in the postnatal visual cortex (Hensch, 2005; Espinosa and Stryker, 2012). When it is deficient, the critical period does not start. When inhibitory maturation or signaling is precocious, it induces a precocious critical period. Heterochronic transplantation of GABAergic interneuron precursors derived from the medial ganglionic eminence (MGE) can induce a second period of functional plasticity in the visual cortex (Southwell et al., 2010). Although the timing of MGE transplantation-induced plasticity is dictated by the maturation of the transplanted cells, its mechanisms remain largely unknown. Here, we sought to test the effect of blocking vesicular GABA loading and subsequent release by transplanted interneurons on the ability to migrate, integrate, and induce plasticity in the host circuitry. We show that MGE cells taken from male and female donors that lack vesicular GABA transporter (Vgat) expression disperse and differentiate into somatostatin- and parvalbumin-expressing interneurons upon heterochronic transplantation in the postnatal mouse cortex. Although transplanted Vgat mutant interneurons come to express mature interneuron markers and display electrophysiological properties similar to those of control cells, their morphology is significantly more complex. Significantly, Vgat mutant MGE transplants fail to induce ODP, demonstrating the pivotal role of vesicular GABAergic transmission for MGE transplantation-induced plasticity in the postnatal mouse visual cortex.SIGNIFICANCE STATEMENT Embryonic inhibitory neurons thrive when transplanted into postnatal brains, migrating and differentiating in the host as they would have done if left in the donor. Once integrated into the host, these new neurons can have profound effects. For example, in the visual cortex, such neurons induce a second critical period of activity-dependent plasticity when they reach the appropriate stage of development. The cellular mechanism by which these transplanted GABAergic interneurons induce plasticity is unknown. Here, we show that transplanted interneurons that are unable to fill synaptic vesicles with GABA migrate and integrate into the host circuit, but they do not induce a second period of plasticity. These data suggest a role for the vesicular GABA transporter in transplantation-mediated plasticity.
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Período Crítico Psicológico , Interneuronas/metabolismo , Interneuronas/trasplante , Plasticidad Neuronal/fisiología , Proteínas del Transporte Vesicular de Aminoácidos Inhibidores/biosíntesis , Corteza Visual/metabolismo , Animales , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Estimulación Luminosa/métodos , Corteza Visual/crecimiento & desarrolloRESUMEN
The responses of neurons in the visual cortex (V1) of adult mammals have long been thought to be stable over long periods. Here, we investigated whether repeated exposure to specific stimuli would enhance V1 visual responses in mice using intrinsic signal imaging through the intact skull and two-photon imaging of calcium signals in single neurons. Mice ran on Styrofoam balls floating on air while viewing one of three different, high-contrast visual stimuli. V1 responses to the stimuli that were viewed by the animal were specifically enhanced, while responses to other stimuli were unaffected. Similar exposure in stationary mice or in mice in which NMDA receptors were partially blocked did not significantly enhance responses. These findings indicate that stimulus-specific plasticity in the adult visual cortex depends on concurrent locomotion, presumably as a result of the high-gain state of the visual cortex induced by locomotion.SIGNIFICANCE STATEMENT We report a rapid and persistent increase in visual cortical responses to visual stimuli presented during locomotion in intact mice. We first used a method that is completely noninvasive to image intrinsic signals through the intact skull. We then measured the same effects on single neurons using two-photon calcium imaging and found that the increase in response to a particular stimulus produced by locomotion depends on how well the neuron is initially driven by the stimulus. To our knowledge, this is the first time such enhancement has been described in single neurons or using noninvasive measurements.
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Locomoción/fisiología , Red Nerviosa/fisiología , Plasticidad Neuronal/fisiología , Estimulación Luminosa/métodos , Corteza Visual/fisiología , Percepción Visual/fisiología , Animales , Potenciales Evocados Visuales/fisiología , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Análisis y Desempeño de TareasRESUMEN
Because ≈90% of malaria cases occur in Africa, emergence of artemisinin-resistant Plasmodium falciparum in Africa poses a serious public health threat. To assess emergence of artemisinin-resistant parasites in Uganda during 2014-2016, we used the recently developed ex vivo ring-stage survival assay, which estimates ring-stage-specific P. falciparum susceptibility to artemisinin. We conducted 4 cross-sectional surveys to assess artemisinin sensitivity in Gulu, Uganda. Among 194 isolates, survival rates (ratio of viable drug-exposed parasites to drug-nonexposed controls) were high (>10%) for 4 isolates. Similar rates have been closely associated with delayed parasite clearance after drug treatment and are considered to be a proxy for the artemisinin-resistant phenotype. Of these, the PfKelch13 mutation was observed in only 1 isolate, A675V. Population genetics analysis suggested that these possibly artemisinin-resistant isolates originated in Africa. Large-scale surveillance of possibly artemisinin-resistant parasites in Africa would provide useful information about treatment outcomes and help regional malaria control.
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Antimaláricos/farmacología , Artemisininas/farmacología , Resistencia a Medicamentos , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Plasmodium falciparum/efectos de los fármacos , Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Preescolar , Estudios Transversales , Femenino , Genotipo , Historia del Siglo XXI , Humanos , Malaria Falciparum/historia , Malaria Falciparum/mortalidad , Masculino , Mutación , Fenotipo , Plasmodium falciparum/genética , Tasa de Supervivencia , Uganda/epidemiología , Secuenciación Completa del GenomaRESUMEN
Accumulation of amyloid-ß protein (Aß) in the brain causes cognitive impairment in Alzheimer's disease. We hypothesized that an extracorporeal system that rapidly removed Aß from the blood may accelerate Aß drainage from the brain. We previously reported that dialyzers remove blood Aßs effectively, mainly by adsorption on the inner surfaces of the hollow fibers, resulting in lower Aß accumulation in the brains of patients undergoing hemodialysis than the controls without hemodialysis. The aim of the present study was to create a more convenient and effective blood Aß removal system using adsorptive filtration, in which the filtrate returned to the body. Filtration from inside to outside of the fibers may enhance the adsorption of plasma Aßs on the surface of micropores inside the hollow fiber walls. Hence, pool solutions of 4 ng/mL synthetic Aß1-40 and Aß1-42 peptides (300 mL) or human plasma (1000 mL of 250-346 pg/mL Aß1-40 and 30-48 pg/mL Aß1-42) were circulated through polysulfone dialyzers at a flow rate of 50 mL/min to evaluate an adsorptive filtration system. The rates of Aß reduction from the pool solutions significantly increased along with the filtration rates. A filtration rate of > 1 mL/min, preferably 5-10 mL/min resulted in an 80-100% reduction of Aßs within 30 min of circulation. The rates of Aßs passing through the membrane walls were maintained around 0% for plasma Aßs during circulation. Thus, our adsorptive filtration systems may be useful for removing blood Aßs for patients with Alzheimer's disease.
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Enfermedad de Alzheimer/terapia , Péptidos beta-Amiloides/aislamiento & purificación , Hemodiafiltración , Adsorción , Péptidos beta-Amiloides/sangre , Encéfalo , Filtración , Humanos , Polímeros , Diálisis Renal , SulfonasRESUMEN
Underlying the complexity of the mammalian brain is its network of neuronal connections, but also the molecular networks of signaling pathways, protein interactions, and regulated gene expression within each individual neuron. The diversity and complexity of the spatially intermingled neurons pose a serious challenge to the identification and quantification of single neuron components. To address this challenge, we present a novel approach for the study of the ribosome-associated transcriptome-the translatome-from selected subcellular domains of specific neurons, and apply it to the Purkinje cells (PCs) in the rat cerebellum. We combined microdissection, translating ribosome affinity purification (TRAP) in nontransgenic animals, and quantitative nanoCAGE sequencing to obtain a snapshot of RNAs bound to cytoplasmic or rough endoplasmic reticulum (rER)-associated ribosomes in the PC and its dendrites. This allowed us to discover novel markers of PCs, to determine structural aspects of genes, to find hitherto uncharacterized transcripts, and to quantify biophysically relevant genes of membrane proteins controlling ion homeostasis and neuronal electrical activities.
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Perfilación de la Expresión Génica , Células de Purkinje/metabolismo , Animales , Sitios de Unión , Mapeo Cromosómico , Análisis por Conglomerados , Citoplasma/metabolismo , Dendritas/metabolismo , Retículo Endoplásmico Rugoso/metabolismo , Familia de Multigenes , Regiones Promotoras Genéticas , Biosíntesis de Proteínas , ARN no Traducido/genética , ARN no Traducido/metabolismo , Ratas , Ribosomas/fisiología , TranscriptomaRESUMEN
Modulation of the calcium sensing receptor (CaSR) is one of the physiological activities of γ-glutamyl peptides such as glutathione (γ-glutamylcysteinylglycine). γ-Glutamyl peptides also possess a flavoring effect, i.e., sensory activity of kokumi substances, which modifies the five basic tastes when added to food. These activities have been shown to be positively correlated, suggesting that kokumi γ-glutamyl peptides are perceived through CaSRs in humans. Our research is based on the hypothesis that the discovery of highly active CaSR agonist peptides will lead to the creation of practical kokumi peptides. Through continuous study of the structure-CaSR-activity relation of a large number of γ-glutamyl peptides, we have determined that the structural requirements for intense CaSR activity of γ-glutamyl peptides are as follows: existence of an N-terminal γ-L-glutamyl residue; existence of a moderately sized, aliphatic, neutral substituent at the second residue in an L-configuration; and existence of a C-terminal carboxylic acid, preferably with the existence of glycine as the third constituent. By the sensory analysis of γ-glutamyl peptides selected by screening using the CaSR activity assay, γ-glutamylvalylglycine was found to be a potent kokumi peptide. Furthermore, norvaline-containing γ-glutamyl peptides, i.e., γ-glutamylnorvalylglycine and γ-glutamylnorvaline, possessed excellent sensory activity of kokumi substances. A novel, practical industrial synthesis of regiospecific γ-glutamyl peptides is also required for their commercialization, which was achieved through the ring opening reaction of N-α-carbobenzoxy-L-glutamic anhydride and amino acids or peptides in the presence of N-hydroxysuccinimide.
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Oligopéptidos/química , Oligopéptidos/farmacología , Receptores Sensibles al Calcio/agonistas , Animales , Células HEK293 , Humanos , Conformación Molecular , Oocitos/metabolismo , Receptores Sensibles al Calcio/metabolismo , Relación Estructura-Actividad , XenopusRESUMEN
In the pathway of melanin biosynthesis, cysteine (Cys) is utilized for the synthesis of pheomelanin. Accordingly, Cys is considered to suppress the formation of brown-black eumelanin. Although attempts have been made to utilize Cys and its derivatives as skin-whitening agents, their instability and odor hinders their application as a cosmetic agent. Herein, N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid ethyl ester (AcCP2Et) was proposed as a candidate for a stable and prolonged-release derivative of Cys to inhibit dopachrome formation after its degradation in melanocytes. It was synthesized by acetylation of 2-methylthiazolidine-2,4-dicarboxylic acid 2-ethyl ester (CP2Et), the condensation derivative of Cys and ethyl pyruvate. AcCP2Et suppressed melanogenesis in melanocytes in vitro, was stable in phosphate buffer at 70°C for five days, and exhibited far less odor than CP2Et. Therefore, AcCP2Et was validated to be a useful deriative of Cys for application as a skin-whitening agent. AcCP2Et comprises four stereoisomers; thus characterization of each stereoisomer was required. The stereochemistry of AcCP2Et was confirmed via a single-crystal X-ray structure analysis of N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid (AcCP) derived from AcCP2Et. In the synthesis of AcCP2Et, the acetylation of CP2Et proceeded with epimerization at C4 to give trans-isomers when excess acetyl chloride and an organic amine was used, whereas it proceeded while retaining the original (R) configuration at C4 to give the cis- and trans-isomer when an equivalent of acetyl chloride with an inorganic base was used. These results indicate that the formation of an intermolecular mixed acid anhydride is responsible for the isomerization at the C4 asymmetric center.
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Cisteína/química , Melaninas/biosíntesis , Preparaciones para Aclaramiento de la Piel/síntesis química , Preparaciones para Aclaramiento de la Piel/farmacología , Tiazolidinas/síntesis química , Tiazolidinas/farmacología , Cristalografía por Rayos X , Melaninas/química , Modelos Moleculares , Conformación Molecular , Preparaciones para Aclaramiento de la Piel/química , Tiazolidinas/químicaRESUMEN
BACKGROUND: Approximately 80% of non-communicable diseases (NCDs) have been reported in low- and middle-income countries (LMICs). However, studies on the usefulness of educational interventions run by non-healthcare workers in combating NCDs in resource-limited areas in rural parts of LMICs are limited. This study aimed to identify the effectiveness of a community-based simple educational program run by non-healthcare trained staff for several outcomes associated with NCDs in a resource-limited area. METHODS: Six villages in the Narail district in Bangladesh were selected, two each in the first and second intervention and the control groups, in the Narail district in Bangladesh were selected. Pre- and post-intervention survey data were collected. The first intervention group received the "strong" educational intervention that included a checklist poster on the wall, phone call messages, personalized advice papers, seminar videos, and face-to-face seminars. The second intervention group received a "weak" intervention that included only a checklist poster on the wall in their house. The outcome was the proportion of NCDs and changes in systolic blood pressure and blood sugar level. Confidential fixed-effects logistic regression and multiple linear regression were performed to identify the effectiveness of the intervention. RESULTS: Overall, 600 participants completed the baseline survey and the follow-up survey. The mean systolic blood pressure reduced by 7.3 mm Hg (95% confidence interval [CI] 4.6-9.9) in the first intervention group, 1.9 mm Hg (95% CI - 0.5-4.2) in the second intervention group, and 4.7 mm Hg (95% CI 2.4-7.0) in the control group. Multiple linear regression analysis showed that the between-group differences in the decline in systolic blood pressure were significant for the first intervention versus control (p = 0.001), but not for the second intervention versus control (p = 0.21). The between-group differences in the reduction in blood glucose after the intervention, were not significant on multiple linear regression analysis. CONCLUSIONS: Community-based educational interventions for NCDs provided by non-healthcare staff improved the outcomes of hypertension and risk behaviors. Well-designed community-based educational interventions should be frequently implemented to reduce NCDs in rural areas of low- and middle-income countries. Trial registration UMIN Clinical Trials Registry (UMIN-CTR; UMIN000050171) retrospectively registered on January 29, 2023.
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Background: Combining multiple tumor markers increases sensitivity for lung cancer diagnosis in the cost of false positive. However, some would like to check as many as tumor markers in the fear of missing cancer. We though to propose a panel of fewer tumor markers for lung cancer diagnosis. Methods: Patients with suspected lung cancer who simultaneously underwent all six tests [carcinoembryonic antigen (CEA), cytokeratin-19 fragment (CYFRA), squamous cell carcinoma-associated antigen (SCC), neuron-specific enolase (NSE), pro-gastrin-releasing peptide (ProGRP), and sialyl Lewis-X antigen (SLX)] were included. Tumor markers with significant impact on the lung cancer in a logistic regression model were included in our panel. Area under the curve (AUC) was compared between our panel and the panel of all six. Results: We included 1,733 [median 72 years, 1,128 men, 605 women, 779 (45%) confirmed lung cancer]. Logistic regression analysis suggested CEA, CYFRA, and NSE were independently associated with the lung cancer diagnosis. The panel of these three tumor markers [AUC =0.656, 95% confidence interval (CI): 0.630-0.682, sensitivity 0.650, specificity 0.662] had better (P<0.001) diagnostic performance than six tumor markers (AUC =0.575, 95% CI: 0.548-0.602, sensitivity 0.829, specificity 0.321). Conclusions: Compared to applying all six markers (at least one marker above the upper limit of normal), the panel with three markers (at least one marker above the upper limit of normal) led to a better predictive value by lowering the risk of false positives.
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Sensory experience in early postnatal life shapes neuronal connections in the brain. Here we report that the local synthesis of brain-derived neurotrophic factor (BDNF) in dendrites plays an important role in this process. We found that dendritic spines of layer 2/3 pyramidal neurons of the visual cortex in mutant mice lacking dendritic Bdnf mRNA and thus local BDNF synthesis were normal at 3 weeks of age, but thinner, longer, and more closely spaced (morphological features of immaturity) at 4 months of age than in wild-type (WT) littermates. Layer 2/3 of the visual cortex in these mutant animals also had fewer GABAergic presynaptic terminals at both ages. The overall size and shape of dendritic arbors were, however, similar in mutant and WT mice at both ages. By using optical imaging of intrinsic signals and single-unit recordings, we found that mutant animals failed to recover cortical responsiveness following monocular deprivation (MD) during the critical period, although they displayed normally the competitive loss of responsiveness to an eye briefly deprived of vision. Furthermore, MD still induced a loss of responsiveness to the closed eye in adult mutant mice, but not in adult WT mice. These results indicate that dendritic BDNF synthesis is required for spine pruning, late-phase spine maturation, and recovery of cortical responsiveness following sensory deprivation. They also suggest that maturation of dendritic spines is required for the maintenance of cortical responsiveness following sensory deprivation in adulthood.
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Factor Neurotrófico Derivado del Encéfalo/biosíntesis , Espinas Dendríticas/metabolismo , Privación Sensorial/fisiología , Corteza Visual/citología , Corteza Visual/metabolismo , Animales , Dendritas/metabolismo , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones MutantesRESUMEN
Experience-dependent cortical plasticity has been studied by using loss-of-function methods. Here, we take the complementary approach of using a genetic gain-of-function that enhances plasticity. We show that a constitutively active form of H-ras (H-ras(G12V)), expressed presynaptically at excitatory synapses in mice, accelerates and enhances multiple, mechanistically distinct forms of plasticity in the developing visual cortex. In vivo, H-ras(G12V) not only increased the rate of ocular dominance change in response to monocular deprivation (MD), but also accelerated recovery from deprivation by reverse occlusion. In vitro, H-ras(G12V) expression decreased baseline presynaptic release probability and enhanced presynaptically expressed long-term potentiation (LTP). H-ras(G12V) expression also accelerated the increase following MD in the frequency of miniature excitatory potentials, mirroring accelerated plasticity in vivo. These findings demonstrate accelerated neocortical plasticity, which offers an avenue toward future therapies for many neurological and neuropsychiatric disorders.
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Genes ras , Potenciación a Largo Plazo , Sinapsis/metabolismo , Corteza Visual/metabolismo , Animales , Humanos , Ratones , Ratones Transgénicos , Sinapsis/genética , Corteza Visual/patologíaRESUMEN
BACKGROUND: Developmental myelination is a protracted process in the mammalian brain. One theory for why oligodendrocytes mature so slowly posits that myelination may stabilize neuronal circuits and temper neuronal plasticity as animals age. We tested this hypothesis in the visual cortex, which has a well-defined critical period for experience-dependent neuronal plasticity. OBJECTIVES/METHODS: To prevent myelin progression, we conditionally deleted Myrf, a transcription factor necessary for oligodendrocyte maturation, from oligodendrocyte precursor cells (Myrf cKO) in adolescent mice. To induce experience-dependent plasticity, adult control and Myrf cKO mice were monocularly deprived by eyelid suture. Functional and structural neuronal plasticity in the visual cortex were assessed in vivo by intrinsic signal optical imaging and longitudinal two photon imaging of dendritic spines, respectively. RESULTS: During adolescence, visual experience modulated the rate of oligodendrocyte maturation in visual cortex. Myrf deletion from oligodendrocyte precursors during adolescence led to inhibition of oligodendrocyte maturation and myelination that persisted into adulthood. Following monocular deprivation, visual cortex activity in response to visual stimulation of the deprived eye remained stable in adult control mice, as expected for post-critical period animals. By contrast, visual cortex responses to the deprived eye decreased significantly following monocular deprivation in adult Myrf cKO mice, reminiscent of the plasticity observed in adolescent mice. Furthermore, visual cortex neurons in adult Myrf cKO mice had fewer dendritic spines and a higher level of spine turnover. Finally, monocular deprivation induced spatially coordinated spine size decreases in adult Myrf cKO, but not control, mice. CONCLUSIONS: These results demonstrate a critical role for oligodendrocytes in shaping the maturation and stabilization of cortical circuits and support the concept of myelin acting as a brake on neuronal plasticity during development.
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Background: Immune checkpoint inhibitors (ICIs) have shown remarkable therapeutic outcomes among cancer patients. Durvalumab plus tremelimumab (DT) is under investigation as a new ICI combination therapy, and its efficacy has been reported in various types of cancer. However, the safety profile of DT remains unclear, especially considering rare adverse events (AEs). Objective: We aimed to assess the frequency of AEs associated with DT. Design: This study type is a systematic review and meta-analysis. Data Sources and Methods: Four databases were searched for articles. Randomized trials, single-arm trials, and prospective and retrospective observational studies were included. The type of cancer, previous treatment, and performance status were not questioned. Major AE indicators such as any AE and the pooled frequency of each specific AE were used as outcomes. As a subgroup analysis, we also compared cases in which DT was performed as first-line treatment with those in which it was performed as second-line or later treatment. The protocol for this systematic review was registered on the University Hospital Medical Information Network (UMIN) Center website (ID: UMIN000046751). Results: Forty-one populations including 3099 patients were selected from 30 articles. Pooled frequencies of key AE indicators are shown below: any AEs, 77.8% [95% confidence interval (CI): 67.9-87.6]; grade ⩾ 3 AEs, 29.3% (95% CI: 24.2-34.4); serious AEs, 34.9% (95% CI: 28.1-41.7); AE leading to discontinuation, 13.3% (95% CI: 9.3-17.4); treatment-related deaths, 0.98% (95% CI: 0.5-1.5). AEs with a frequency exceeding 15% are shown below: fatigue, 30.1% (95% CI: 23.8-36.3); diarrhea, 21.7% (95% CI: 17.8-25.6); pruritus 17.9% (95% CI: 14.4-21.3); decreased appetite, 17.7% (95% CI: 13.7-22.0); nausea, 15.6% (95% CI: 12.1-19.6). There were no significant differences in these pooled frequencies between subgroups. Conclusions: The incidence of any AE in DT therapy was approximately 78%, and the incidence of grade 3 or higher AEs was approximately 30%, which was independent of prior therapy.
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Changes in visual cortical responses that are induced by monocular visual deprivation are a widely studied example of competitive, experience-dependent neural plasticity. It has been thought that the deprived-eye pathway will fail to compete against the open-eye pathway for limited amounts of brain-derived neurotrophic factor, which acts on TrkB and is needed to sustain effective synaptic connections. We tested this model by using a chemical-genetic approach in mice to inhibit TrkB kinase activity rapidly and specifically during the induction of cortical plasticity in vivo. Contrary to the model, TrkB kinase activity was not required for any of the effects of monocular deprivation. When the deprived eye was re-opened during the critical period, cortical responses to it recovered. This recovery was blocked by TrkB inhibition. These findings suggest a more conventional trophic role for TrkB signaling in the enhancement of responses or growth of new connections, rather than a role in competition.
Asunto(s)
Receptor trkB/metabolismo , Privación Sensorial/fisiología , Visión Monocular/fisiología , Corteza Visual/metabolismo , Vías Visuales/fisiología , Sustitución de Aminoácidos , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Lateralidad Funcional/fisiología , Ratones , Ratones Mutantes , Inhibición Neural/fisiología , Plasticidad Neuronal/fisiología , Receptor trkB/genética , Recuperación de la Función/fisiologíaRESUMEN
PURPOSE: Amyloid-ß (Aß) is a brain protein that causes Alzheimer's disease. We have revealed that extracorporeal blood Aß-removal systems evoked a large Aß influx into the blood. This study investigated the system that is more effective in evoking Aß influx. METHODS: Aß removal activities were compared between hexadecyl-alkylated cellulose beads (HexDC) and fragments of polysulfone hollow fibers (PSf-HFs) in mini-columns to eliminate the filtration effect. Then, adsorptive filtration systems were adapted for PSf hemodialyzers to enhance Aß adsorption on micropores in the wall of hollow fibers. Plasma Aß concentrations of patients with renal failure were analyzed during treatment with PSf hemodialyzers alone for 8 h or tandemly connected HexDC and PSf hemodialyzers for 4 h. RESULTS: In the in vitro study, Aß removal efficiency for HexDC was approximately 100% during the 60 min treatment, whereas the removal efficiency for PSf-HF fragments gradually decreased. However, PSf hemodialyzer in adsorptive filtration systems removed Aßs comparably or more than HexDC. Aß influx into the blood increases time-dependently. Concomitant use of HexDC and PSf hemodialyzer evoked a larger Aß1-40 influx than that of PSf hemodialyzer alone. However, Aß1-42 influx by PSf hemodialyzer alone was similar to or a little larger than influx by the combined system. Both systems evoked almost doubled Aß influx than estimated Aßs existing in the normal brain during the 4 h treatment. CONCLUSION: PSf hemodialyzer alone for a longer period and concomitant use of HexDC and PSf hemodialyzer for a shorter time effectively evoked a larger Aß influx. To evoke Aß1-42 influx, PSf hemodialyzer alone was effective enough. These findings of devices and treatment time may lead to optimal clinical settings for therapy and prevention of Alzheimer's disease.
RESUMEN
Ephrin-As and their receptors, EphAs, are expressed in the developing cortex where they may act to organize thalamic inputs. Here, we map the visual cortex (V1) in mice deficient for ephrin-A2, -A3, and -A5 functionally, using intrinsic signal optical imaging and microelectrode recording, and structurally, by anatomical tracing of thalamocortical projections. V1 is shifted medially, rotated, and compressed and its internal organization is degraded. Expressing ephrin-A5 ectopically by in utero electroporation in the lateral cortex shifts the map of V1 medially, and expression within V1 disrupts its internal organization. These findings indicate that interactions between gradients of EphA/ephrin-A in the cortex guide map formation, but that factors other than redundant ephrin-As are responsible for the remnant map. Together with earlier work on the retinogeniculate map, the current findings show that the same molecular interactions may operate at successive stages of the visual pathway to organize maps.