Search results for "Response"
showing 10 items of 4136 documents
Reduced presynaptic efficiency of excitatory synaptic transmission impairs LTP in the visual cortex of BDNF-heterozygous mice
2006
The neurotrophin brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival, axonal and dendritic growth and synapse formation. BDNF has also been reported to mediate visual cortex plasticity. Here we studied the cellular mechanisms of BDNF-mediated changes in synaptic plasticity, excitatory synaptic transmission and long-term potentiation (LTP) in the visual cortex of heterozygous BDNF-knockout mice (BDNF(+/-)). Patch-clamp recordings in slices showed an approximately 50% reduction in the frequency of miniature excitatory postsynaptic currents (mEPSCs) compared to wild-type animals, in the absence of changes in mEPSC amplitudes. A presynaptic impairment of excita…
Beta-amyloid monomers are neuroprotective
2009
The 42-aa-long β-amyloid protein—Aβ1-42—is thought to play a central role in the pathogenesis of Alzheimer's disease (AD) (Walsh and Selkoe, 2007). Data from AD brain (Shankar et al., 2008), transgenic APP (amyloid precursor protein)-overexpressing mice (Lesné et al., 2006), and neuronal cultures treated with synthetic Aβ peptides (Lambert et al., 1998) indicate that self-association of Aβ1-42monomers into soluble oligomers is required for neurotoxicity. The function of monomeric Aβ1-42is unknown. The evidence that Aβ1-42is present in the brain and CSF of normal individuals suggests that the peptide is physiologically active (Shoji, 2002). Here we show that synthetic Aβ1-42monomers support …
The effects of glutamate receptor antagonists on cerebellar granule cell survival and development.
2007
N-Methyl-d-aspartate (NMDA) receptor stimulation promotes neuronal survival and differentiation under both in vitro and in vivo conditions. We studied the effects of various NMDA receptor antagonists acting at different NMDA receptor binding sites and non-NMDA receptor antagonists on the development and survival of cerebellar granule cell (CGC) culture. Only three of the drugs tested induced neurotoxicity-MK-801 (non-competitive NMDA channel blocking antagonist), ifenprodil (an antagonist of the NR2B site and polyamine site of the NMDA receptor) and L-701.324 (full antagonist at glycine site), while CGP-37849 (a competitive NMDA antagonist), (+)-HA-966 (a partial agonist of the glycine site…
Action of anticonvulsants on hippocampal slices in Mg-free medium
1989
The effects of six prototype anticonvulsant drugs were investigated on epileptiform field potential discharges evoked in hippocampal slices of rats by removing magnesium ions from the perfusion fluid in order to reveal a possible interaction with N-methyl-D-aspartate (NMDA) receptor activation. All drugs reduced the multiple discharges with the following order of potency: midazolam greater than carbamazepine = phenytoin = phenobarbital greater than ethosuximide = valproate. They had a stronger depressant effect on the later population spikes but none of them abolished the epileptiform discharge. These effects can be explained by known mechanisms of action of the anticonvulsants tested and l…
Design, modelling, and analysis of a large floating dock for spar floating wind turbine installation
2020
Installation of floating wind turbines at the offshore site is a challenging task. A significant part of the time efficiency and costs are related to the installation methods which are sensitive to weather conditions. This study investigates a large floating dock concept, which can be used to shield a floating wind turbine during installation of tower, nacelle, and rotor onto a spar foundation. In this paper, the concept is described in detail, and a design optimisation is carried out using simple design constraints. Hydrodynamic analysis and dynamic response analysis of the coupled system of the optimum dock and spar are conducted. Two spars of different sizes are considered, and the motio…
Role of Ge nanoclusters in the performance of photodetectors compatible with Si technology
2013
In this work, we investigate the spectral response of metal-oxide- semiconductor photodetectors based on Ge nanoclusters (NCs) embedded in a silicon dioxide (SiO2) matrix. The role of Ge NC size and density on the spectral response was evaluated by comparing the performance of PDs based on either densely packed arrays of 2 nm-diameter NCs or a more sparse array of 8 nm-diameter Ge NCs. Our Ge NC photodetectors exhibit a high spectral responsivity in the 500-1000 nm range with internal quantum efficiency of ~ 700% at - 10 V, and with NC array parameters such as NC density and size playing a crucial role in the photoconductive gain and response time. We find that the configuration with a more…
Optimal degradation of Ciprofloxacin in a heterogeneous Fenton-like process using (δ-FeOOH)/MWCNTs nanocomposite
2021
Abstract This study was aimed at the synthesis and characterization of ( δ -FeOOH)/MWCNTs nanocomposite as the catalyst for Ciprofloxacin (CIP) removal through a heterogeneous Fenton-like process. The proposed experimental design applies the central composite design (CCD) as a response surface methodology (RSM). The effect of influential parameters, including initial CIP concentration, catalyst dose, H 2 O2 concentration, initial pH, and reaction time on removal, were investigated. ( δ -FeOOH)/MWCNTs nanocomposite was synthesized using a single-step co-precipitation technique. Besides, nano-feroxyhyte and nanocomposite properties were characterized by transmission electron microscopy (TEM),…
Lipid nanocarriers containing esters prodrugs of Flurbiprofen. Preparation, physical-chemical characterization and biological studies.
2013
In this paper, the preparation, chemical-physical, technological and in vitro characterization of nanostructured lipid carriers (NLC) carrying R-flurbiprofen ester prodrugs, were analyzed for a potential pharmaceutical application. R-flurbiprofen was chosen as a model drug because it has been found to play an effective role in counteracting secretases involved in neurodegenerative diseases, although it does not cross the Blood Brain Barrier (BBB). In this study, two R-flurbiprofen ester prodrugs (ethyl and hexyl) were successfully synthesized and entrapped into non-pegylated and pegylated NLC. The obtained systems showed average diameters in the colloidal size range, negative zeta potential…
Cross-reinstatement by cocaine and amphetamine of morphine-induced place preference in mice
2005
The cross-reinstatement by psychostimulants of a conditioned place preference (CPP) induced by morphine was evaluated in mice. In Experiment 1, we examined the effects of a single dose of cocaine and amphetamine on a previously extinguished morphine CPP. After acquisition of CPP induced by morphine (40 mg/kg), animals underwent daily extinction sessions of 15 min duration until the CPP was extinguished. Subsequently, animals received a non-contingent injection of cocaine (25 mg/kg) or amphetamine (4 mg/kg), which produced the reinstatement of the extinguished morphine-induced CPP. In Experiment 2, we evaluated the reinstating effects of several priming doses of cocaine (Experiment 2A) or am…
Intracellular glutathione in human hepatocytes incubated with S-adenosyl-L-methionine and GSH-depleting drugs
1991
Abstract The present study was undertaken to investigate (a) whether S- adenosyl- L -methionine (SAMe) added to culture medium can increase intracellular glutathione (GSH) levels in human hepatocytes and (b) whether SAMe can prevent the GSH depletion found in human hepatocytes incubated with GSH-depleting drugs (paracetamol, opiates, ethanol). Incubation of hepatocytes with increasing concentrations of SAMe resulted in a dose-dependent elevation of intracellular GSH content, which reached its maximum (35% increase) at 30 μM after 20 h. SAMe, as the only sulfur source in the medium, was efficient in repleting GSH-depleted hepatocytes following treatment with diethyl maleate. Incubation of hu…