445 research outputs found

    Central synapses release a resource-efficient amount of glutamate.

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    Why synapses release a certain amount of neurotransmitter is poorly understood. We combined patch-clamp electrophysiology with computer simulations to estimate how much glutamate is discharged at two distinct central synapses of the rat. We found that, regardless of some uncertainty over synaptic microenvironment, synapses generate the maximal current per released glutamate molecule while maximizing signal information content. Our result suggests that synapses operate on a principle of resource optimization

    TARP γ-7 selectively enhances synaptic expression of calcium-permeable AMPARs

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    Regulation of calcium-permeable AMPA receptors (CP-AMPARs) is crucial in normal synaptic function and neurological disease states. Although transmembrane AMPAR regulatory proteins (TARPs) such as stargazin (γ-2) modulate the properties of calcium-impermeable AMPARs (CI-AMPARs) and promote their synaptic targeting, the TARP-specific rules governing CP-AMPAR synaptic trafficking remain unclear. We used RNA interference to manipulate AMPAR-subunit and TARP expression in γ-2–lacking stargazer cerebellar granule cells—the classic model of TARP deficiency. We found that TARP γ-7 selectively enhanced the synaptic expression of CP-AMPARs and suppressed CI-AMPARs, identifying a pivotal role of γ-7 in regulating the prevalence of CP-AMPARs. In the absence of associated TARPs, both CP-AMPARs and CI-AMPARs were able to localize to synapses and mediate transmission, although their properties were altered. Our results also establish that TARPed synaptic receptors in granule cells require both γ-2 and γ-7 and reveal an unexpected basis for the loss of AMPAR-mediated transmission in stargazer mice

    Driven Assembly of Lignin into Microcapsules for Storage and Delivery of Hydrophobic Molecules

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    Oil-filled microcapsules of kraft lignin were synthe- sized by first creating an oil in water emulsion followed by a high- intensity, ultrasound-assisted cross-linking of lignin at the water/oil interface. The rationale behind our approach is based on promoting documented lignin hydrophobic interactions within the oil phase, followed by locking the resulting spherical microsystems by covalent cross-linking using a high intensity ultrasound treatment. As further evidence in support of our rationale, confocal and optical microscopies demonstrated the uniformly spherical morphology of the created lignin microparticles. The detailed elucidation of the cross-linking processes was carried out using gel permeation chromatography (GPC) and quantitative 31P NMR analyses. The ability of lignin microcapsules to incorporate and release Coumarin-6 was evaluated in detail. In vitro studies and confocal laser scanning microscopy analysis were carried out to assess the internalization of capsules into Chinese hamster ovary (CHO) cells. This part of our work demonstrated that the lignin microcapsules are not cytotoxic and readily incorporated in the CHO cells

    The Role of Percentage of Prostate-specific Antigen Reduction After Focal Therapy Using High-intensity Focused Ultrasound for Primary Localised Prostate Cancer. Results from a Large Multi-institutional Series

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    Focal therapy (FT) for prostate cancer (PCa) is emerging as a novel therapeutic approach for patients with low- to intermediate-risk disease, in order to provide acceptable oncological control, whilst avoiding the side effects of radical treatment. Evidence regarding the ideal follow-up strategy and the significance of prostate-specific antigen (PSA) kinetics after treatment is needed. In this study, we aimed to assess the value of the percentage of PSA reduction (%PSA reduction) after FT in predicting the likelihood of any additional treatment or any radical treatment. We retrospectively analysed a multicentre cohort of 703 men receiving FT for low- and intermediate-risk PCa. Overall, the rates of any additional treatment and any radical treatment were 30% and 13%, respectively. The median follow-up period was 41 mo. The median %PSA reduction after FT was 73%. At Cox multivariable analysis, %PSA reduction was an independent predictor of any additional treatment (hazard ratio [HR]: 0.96; p 90%, the probability of any additional treatment within 5 yr was 20%. Conversely, for %PSA reduction of <10%, the probability of receiving any additional treatment within 5 yr was roughly 70%. This study is the first to assess the role of %PSA reduction in the largest multicentre cohort of men receiving FT for PCa. Given the lack of standardised follow-up strategies in the FT field, the use of the %PSA reduction should be considered

    Comprehensive evaluation of focal therapy complications in prostate cancer: a standardized methodology

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    Purpose: Today, up to one-third of newly diagnosed prostate cancer (PCa) cases may be suitable for focal treatment. The lack of data about the toxicity profiles of lesion-targeting therapies, however, has made it difficult to compare treatment modalities. The aim of the present study was to evaluate comprehensively the incidence, severity, and timing of onset of complications for PCa patients undergoing focal high-intensity focused ultrasound (HIFU) and focal cryosurgical ablation of the prostate (CSAP). Materials and Methods: A total of 336 patients were included who underwent focal HIFU or focal CSAP as a primary treatment for PCa between January 2009 and December 2017. Mean follow-up was 11 months (standard deviation: 3.0). All complications were captured and graded according to severity, and classified by timing of onset. Univariate and multivariate analysis was performed to identify predictors of the most common side effects. Results: There were 98 complications in 79/210 patients (38%) undergoing focal HIFU and 34 complications in 27/126 patients (21%) undergoing focal CSAP. In terms of severity, 95% of the complications of focal HIFU and 91% of the complications of focal CSAP were minor. Most complications presented in the early postoperative period. On multivariate analysis, subtotal HIFU was associated with acute urinary retention (AUR), while a smaller prostate size and longer catheterization time with dysuria. In CSAP patients, longer catheterization time was associated with AUR and urethral sloughing. The main limitation is the nonrandomized and retrospective nature. Conclusions: Focal HIFU and focal CSAP provide a tolerable toxicity, with primarily minor complications presenting in the early postoperative period

    Low Vitamin D in Narcolepsy with Cataplexy

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    Narcolepsy with cataplexy (NC) is currently thought to be an autoimmune-mediated disorder in which environmental risk factors make a significant contribution to its development. It was proposed that vitamin D deficiency plays a role in autoimmune diseases. Here we investigated whether NC can be associated with 25-hydroxyvitamin D (25(OH)D) level deficiency in patients with NC compared with gender- and age-matched normal controls.Serum level of 25 (OH)D was determined in 51 European patients with typical NC compared to 55 age-, gender-, and ethnicity-matched healthy controls. Demographic and clinical data (age at onset, duration and severity of disease at baseline, and treatment intake at time of study) and season of blood sampling were collected to control for confounding variables.Serum 25(OH)D concentration was lower in NC compared to controls (median, 59.45 nmol/l [extreme values 24.05-124.03] vs. 74.73 nmol/l [26.88-167.48] p = 0.0039). Patients with NC had significantly greater vitamin D deficiency (<75 nmol/l) than controls (72.5% vs 50.9%, p = 0.0238). Division into quartiles of the whole sample revealed that the risk of being affected with NC increased with lower 25(OH)D level, with a 5.34 OR [1.65-17.27] for the lowest quartile (p = 0.0051). Further adjustment for BMI did not modify the strength of the association (OR: 3.63, 95% CI = 1.06-12.46, p = 0.0191). No between BMI and 25(OH)D interaction, and no correlation between 25(OH)D level and disease duration or severity or treatment intake were found in NC.We found a higher frequency of vitamin D deficiency in NC. Further studies are needed to assess the contribution of hypovitaminosis D to the risk of developing narcolepsy, and to focus on the utility of assessing vitamin D status to correct potential deficiency

    The Unknown Risk of Vertical Transmission in Sleeping Sickness—A Literature Review

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    Children with human African trypanosomiasis (HAT) present with a range of generally non-specific symptoms. Late diagnosis is frequent with often tragic outcomes. Trypanosomes can infect the foetus by crossing the placenta. Unequivocal cases of congenital infection that have been reported include newborn babies of infected mothers who were diagnosed with HAT in the first 5 days of life and children of infected mothers who had never entered an endemic country themselves

    Reliable Activation of Immature Neurons in the Adult Hippocampus

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    Neurons born in the adult dentate gyrus develop, mature, and connect over a long interval that can last from six to eight weeks. It has been proposed that, during this period, developing neurons play a relevant role in hippocampal signal processing owing to their distinctive electrical properties. However, it has remained unknown whether immature neurons can be recruited into a network before synaptic and functional maturity have been achieved. To address this question, we used retroviral expression of green fluorescent protein to identify developing granule cells of the adult mouse hippocampus and investigate the balance of afferent excitation, intrinsic excitability, and firing behavior by patch clamp recordings in acute slices. We found that glutamatergic inputs onto young neurons are significantly weaker than those of mature cells, yet stimulation of cortical excitatory axons elicits a similar spiking probability in neurons at either developmental stage. Young neurons are highly efficient in transducing ionic currents into membrane depolarization due to their high input resistance, which decreases substantially in mature neurons as the inward rectifier potassium (Kir) conductance increases. Pharmacological blockade of Kir channels in mature neurons mimics the high excitability characteristic of young neurons. Conversely, Kir overexpression induces mature-like firing properties in young neurons. Therefore, the differences in excitatory drive of young and mature neurons are compensated by changes in membrane excitability that render an equalized firing activity. These observations demonstrate that the adult hippocampus continuously generates a population of highly excitable young neurons capable of information processing
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