129 research outputs found

    Suikerbieten als tussenteelt voor vergisting : opbrengst, energierendement, broeikasgasemissiereductie en nutriëntenafvoer

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    In het kader van het project Energieboerderij is de mogelijkheid onderzocht om voor vergisting suikerbieten te telen na een vroegruimend gewas, waarbij de oogst na de winter plaatsvindt (tussenteelt). Alleen bij vroege uitzaai voor begin augustus werden voldoende hoge opbrengsten verkregen met een hoog energierendement en een broeikasgasemissiereductie die voldeed aan het duurzaamheidscriterium. Tussen de onderzochte rassen bestonden er significante verschillen in methaanopbrengst van zowel wortel als loof. Bij vroege zaai met voldoende hoge opbrengst worden aanzienlijke hoeveelheden nutriënten met het gewas afgevoerd. Vooral voor fosfaat kan dit problemen geven, indien er niet voldoende ruimte is om hiervoor te compenseren. Ook is het vorstrisico te groot om altijd na de winter te kunnen oogsten

    Beheersing van Rhizoctonia solani door verhoogde bodemweerbaarheid

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    In de afgelopen jaren is uitgebreid gezocht naar een methodiek die wel de ziektewering tegen Rhizoctonia betrouwbaar kan stimuleren. Hierbij is ontdekt dat de antagonistische bacteriegroep Lysobacter spp., die van nature in diverse Nederlandse gronden voorkomt, correleert met ziektewering. In 2012 zijn voor het eerst veldproeven uitgevoerd

    Astrocyte-mediated short-term synaptic depression in the rat hippocampal CA1 area: two modes of decreasing release probability

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    <p>Abstract</p> <p>Background</p> <p>Synaptic burst activation feeds back as a short-term depression of release probability at hippocampal CA3-CA1 synapses. This short-term synaptic plasticity requires functional astrocytes and it affects both the recently active (< 1 s) synapses (post-burst depression) as well as inactive neighboring synapses (transient heterosynaptic depression). The aim of this study was to investigate and compare the components contributing to the depression of release probability in these two different scenarios.</p> <p>Results</p> <p>When tested using paired-pulses, following a period of inactivity, the transient heterosynaptic depression was expressed as a reduction in the response to only the first pulse, whereas the response to the second pulse was unaffected. This selective depression of only the first response in a high-frequency burst was shared by the homosynaptic post-burst depression, but it was partially counteracted by augmentation at these recently active synapses. In addition, the expression of the homosynaptic post-burst depression included an astrocyte-mediated reduction of the pool of release-ready primed vesicles.</p> <p>Conclusions</p> <p>Our results suggest that activated astrocytes depress the release probability via two different mechanisms; by depression of vesicular release probability only at inactive synapses and by imposing a delay in the recovery of the primed pool of vesicles following depletion. These mechanisms restrict the expression of the astrocyte-mediated depression to temporal windows that are typical for synaptic burst activity.</p

    Duurzaamheid teelt van suikerbieten voor covergisting; resultaten 2008-2010 van vijf telers in het project Energieboerderij

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    In deze IRS-publicatie staan de resultaten uit het project Energieboerderij met betrekking tot vijf telers, waar de suikerbietenteelt drie jaar lang is gevolgd. Alle teelthandelingen en inputs zijn meegenomen in de berekening van het energierendement en de broeikasgasemissiereductie. Aan de hand van deze twee duurzaamheidparameters is de keten suikerbieten en loof voor vergisting doorgerekend. Suikerbieten telen voor (co)vergisting tot groene stroom uit biogas voldoet aan de gestelde eisen voor duurzaamheid met een broeikasgasemissiereductie van gemiddeld 78%. De telers verschilden onderling niet op de twee duurzaamheidscriteria. De methaanopbrengst is sterk gecorreleerd aan de suikeropbrengst. Naast een efficiënte teelt is ook een efficiënte logistiek nodig. Afvoer van loof voor vergisting heeft een positieve bijdrage voor de duurzaamheid. Wel worden er dan aanzienlijke hoeveelheden nutriënten extra afgevoerd

    A genetically encoded reporter of synaptic activity in vivo

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    To image synaptic activity within neural circuits, we tethered the genetically encoded calcium indicator (GECI) GCaMP2 to synaptic vesicles by fusion to synaptophysin. The resulting reporter, SyGCaMP2, detected the electrical activity of neurons with two advantages over existing cytoplasmic GECIs: it identified the locations of synapses and had a linear response over a wider range of spike frequencies. Simulations and experimental measurements indicated that linearity arises because SyGCaMP2 samples the brief calcium transient passing through the presynaptic compartment close to voltage-sensitive calcium channels rather than changes in bulk calcium concentration. In vivo imaging in zebrafish demonstrated that SyGCaMP2 can assess electrical activity in conventional synapses of spiking neurons in the optic tectum and graded voltage signals transmitted by ribbon synapses of retinal bipolar cells. Localizing a GECI to synaptic terminals provides a strategy for monitoring activity across large groups of neurons at the level of individual synapses

    A pilot randomized controlled trial of exercise to improve cognitive performance in patients with stable glioma:A proof of concept

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    BACKGROUND: Patients with glioma often suffer from cognitive deficits. Physical exercise has been effective in ameliorating cognitive deficits in older adults and neurological patients. This pilot randomized controlled trial (RCT) explored the possible impact of an exercise intervention, designed to improve cognitive functioning in glioma patients, regarding cognitive test performance and patient-reported outcomes (PROs). METHODS: Thirty-four clinically stable patients with World Health Organization grades II/III glioma were randomized to a home-based remotely coached exercise group or an active control group. Patients exercised 3 times per week for 20-45 minutes, with moderate to vigorous intensity, during 6 months. At baseline and immediate follow-up, cognitive performance and PROs were assessed with neuropsychological tests and questionnaires, respectively. Linear regression analyses were used to estimate effect sizes of potential between-group differences in cognitive performance and PROs at 6 months. RESULTS: The exercise group (n = 21) had small- to medium-sized better follow-up scores than the control group (n = 11) on several measures of attention and information processing speed, verbal memory, and executive function, whereas the control group showed a slightly better score on a measure of sustained selective attention. The exercise group also demonstrated small- to medium-sized better outcomes on measures of self-reported cognitive symptoms, fatigue, sleep, mood, and mental health-related quality of life. CONCLUSIONS: This small exploratory RCT in glioma patients provides a proof of concept with respect to improvement of cognitive functioning and PROs after aerobic exercise, and warrants larger exercise trials in brain tumor patients

    EGLN1 Inhibition and Rerouting of α-Ketoglutarate Suffice for Remote Ischemic Protection

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    Ischemic preconditioning is the phenomenon whereby brief periods of sublethal ischemia protect against a subsequent, more prolonged, ischemic insult. In remote ischemic preconditioning (RIPC), ischemia to one organ protects others organs at a distance. We created mouse models to ask if inhibition of the alpha-ketoglutarate (αKG)-dependent dioxygenase Egln1, which senses oxygen and regulates the hypoxia-inducible factor (HIF) transcription factor, could suffice to mediate local and remote ischemic preconditioning. Using somatic gene deletion and a pharmacological inhibitor, we found that inhibiting Egln1 systemically or in skeletal muscles protects mice against myocardial ischemia-reperfusion (I/R) injury. Parabiosis experiments confirmed that RIPC in this latter model was mediated by a secreted factor. Egln1 loss causes accumulation of circulating αKG, which drives hepatic production and secretion of kynurenic acid (KYNA) that is necessary and sufficient to mediate cardiac ischemic protection in this setting.Broad Institute of MIT and Harvard. SPARC ProgramBurroughs Wellcome Fun

    AMPA Receptor Activation Causes Silencing of AMPA Receptor-Mediated Synaptic Transmission in the Developing Hippocampus

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    Agonist-induced internalization of transmembrane receptors is a widespread biological phenomenon that also may serve as a mechanism for synaptic plasticity. Here we show that the agonist AMPA causes a depression of AMPA receptor (AMPAR) signaling at glutamate synapses in the CA1 region of the hippocampus in slices from developing, but not from mature, rats. This developmentally restricted agonist-induced synaptic depression is expressed as a total loss of AMPAR signaling, without affecting NMDA receptor (NMDAR) signaling, in a large proportion of the developing synapses, thus creating AMPAR silent synapses. The AMPA-induced AMPAR silencing is induced independently of activation of mGluRs and NMDARs, and it mimics and occludes stimulus-induced depression, suggesting that this latter form of synaptic plasticity is expressed as agonist-induced removal of AMPARs. Induction of long-term potentiation (LTP) rendered the developing synapses resistant to the AMPA-induced depression, indicating that LTP contributes to the maturation-related increased stability of these synapses. Our study shows that agonist binding to AMPARs is a sufficient triggering stimulus for the creation of AMPAR silent synapses at developing glutamate synapses

    Prognostic value and kinetics of circulating endothelial cells in patients with recurrent glioblastoma randomised to bevacizumab plus lomustine, bevacizumab single agent or lomustine single agent. A report from the Dutch Neuro-Oncology Group BELOB trial

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    Background:Angiogenesis is crucial for glioblastoma growth, and anti-vascular endothelial growth factor agents are widely used in recurrent glioblastoma patients. The number of circulating endothelial cells (CECs) is a surrogate marker for endothelial damage. We assessed their kinetics and explored their prognostic value in patients with recurrent glioblastoma.Methods:In this side study of the BELOB trial, 141 patients with recurrent glioblastoma were randomised to receive single-agent bevacizumab or lomustine, or bevacizumab plus lomustine. Before treatment, after 4 weeks and after 6 weeks of treatment, CECs were enumerated.Results:The number of CECs increased during treatment with bevacizumab plus lomustine, but not during treatment in the single-agent arms. In patients treated with lomustine single agent, higher absolute CEC numbers after 4 weeks (log 10 CEC hazard ratio (HR) 0.41, 95% CI 0.18-0.91) and 6 weeks (log 10 CEC HR 0.16, 95% CI 0.05-0.56) of treatment were associated with improved overall survival (OS). Absolute CEC numbers in patients receiving bevacizumab plus lomustine or bevacizumab single agent were not associated wit
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