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Search Results: 1 - 10 of 236812 matches for " Andrea R. Durrant "
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D-Serine in Neuropsychiatric Disorders: New Advances
Andrea R. Durrant,Uriel Heresco-Levy
Advances in Psychiatry , 2014, DOI: 10.1155/2014/859735
Abstract: D-Serine (DSR) is an endogenous amino acid involved in glia-synapse interactions that has unique neurotransmitter characteristics. DSR acts as obligatory coagonist at the glycine site associated with the N-methyl-D-aspartate subtype of glutamate receptors (NMDAR) and has a cardinal modulatory role in major NMDAR-dependent processes including NMDAR-mediated neurotransmission, neurotoxicity, synaptic plasticity, and cell migration. Since either over- or underfunction of NMDARs may be involved in the pathophysiology of neuropsychiatric disorders; the pharmacological manipulation of DSR signaling represents a major drug development target. A first generation of proof-of-concept animal and clinical studies suggest beneficial DSR effects in treatment-refractory schizophrenia, movement, depression, and anxiety disorders and for the improvement of cognitive performance. A related developing pharmacological strategy is the indirect modification of DSR synaptic levels by use of compounds that alter the function of main enzymes responsible for DSR production and degradation. Accumulating data indicate that, during the next decade, we will witness important advances in the understanding of DSR role that will further contribute to elucidating the causes of neuropsychiatric disorders and will be instrumental in the development of innovative treatments. 1. Introduction Although the enzyme D-amino-acid oxidase (DAAO) has been identified in higher organisms in 1935 [1], historically, D-amino acids were thought to be absent in mammalian tissue. This dogma was revolutionized at the beginning of 1990’s when it was found that abundant quantities of free D-serine (DSR) occur in the mammalian brain, at concentrations comparable with those of classical neurotransmitters and higher than those of most essential amino acids [2, 3]. Presently, DSR is considered the most biologically active D-amino acid described in mammalian systems [4]. Phylogenetically, its concentrations appear to be extremely low in the brains of fish, amphibians, and birds, suggesting that endogenous DSR is specifically maintained at high levels in the mammalian brain among vertebrates [5]. In the late 1990s, it was demonstrated that DSR is an obligatory endogenous coagonist of the N-methyl-D-aspartate receptor (NMDAR), functioning in vivo as a specific and potent full agonist at the NMDAR-associated glycine (GLY) modulatory site (GMS). The NMDAR subtype of glutamate (GLU) receptors is widely expressed in the central nervous system (CNS) and has a cardinal role in activity-dependent changes in synaptic
Serum cholinesterases are differentially regulated in normal and dystrophin-deficient mutant mice
Andrea R. Durrant,Liliya Tamayev,Lili Anglister
Frontiers in Molecular Neuroscience , 2012, DOI: 10.3389/fnmol.2012.00073
Abstract: The cholinesterases, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) (pseudocholinesterase), are abundant in the nervous system and in other tissues. The role of AChE in terminating transmitter action in the peripheral and central nervous system is well understood. However, both knowledge of the function(s) of the cholinesterases in serum, and of their metabolic and endocrine regulation under normal and pathological conditions, is limited. This study investigates AChE and BChE in sera of dystrophin-deficient mdx mutant mice, an animal model for the human Duchenne muscular dystrophy (DMD) and in control healthy mice. The data show systematic and differential variations in the concentrations of both enzymes in the sera, and specific changes dictated by alteration of hormonal balance in both healthy and dystrophic mice. While AChE in mdx-sera is elevated, BChE is markedly diminished, resulting in an overall cholinesterase decrease compared to sera of healthy controls. The androgen testosterone (T) is a negative modulator of BChE, but not of AChE, in male mouse sera. T-removal elevated both BChE activity and the BChE/AChE ratio in mdx male sera to values resembling those in healthy control male mice. Mechanisms of regulation of the circulating cholinesterases and their impairment in the dystrophic mice are suggested, and clinical implications for diagnosis and treatment are considered.
Biodegradation of polycyclic aromatic hydrocarbons by soil fungi
Clemente, Andrea R.;Anazawa, Tania A.;Durrant, Lucia R.;
Brazilian Journal of Microbiology , 2001, DOI: 10.1590/S1517-83822001000400001
Abstract: thirteen deuteromycete ligninolytic fungal strains were grown in media containing polycyclic aromatic hydrocarbons (pahs), for 6 and 10 days. the pahs were added directly with the inocula or on the third day of cultivation. a selection of the best strains was carried out based on the levels of degradation of the pahs and also on the ligninolytic activities produced by the fungi. the selected strains were cultivated for 3, 6, 9, 12 and 15 days in the pahs-containing media. degradation of pahs, as measured by reversed-phase hplc on a c18 column, varied with each strain as did the ligninolytic enzymes present in the culture supernatants. highest degradation of naphthalene (69%) was produced by the strain 984, having mn-peroxidase activity, followed by strain 870 (17%) showing lignin peroxidase and laccase activities. the greatest degradation of phenanthrene (12%) was observed with strain 870 containing mn-peroxidase and laccase activities. when anthracene was used, the strain 710 produced a good level of degradation (65%).
Biodegradation of polycyclic aromatic hydrocarbons by soil fungi
Clemente Andrea R.,Anazawa Tania A.,Durrant Lucia R.
Brazilian Journal of Microbiology , 2001,
Abstract: Thirteen deuteromycete ligninolytic fungal strains were grown in media containing polycyclic aromatic hydrocarbons (PAHs), for 6 and 10 days. The PAHs were added directly with the inocula or on the third day of cultivation. A selection of the best strains was carried out based on the levels of degradation of the PAHs and also on the ligninolytic activities produced by the fungi. The selected strains were cultivated for 3, 6, 9, 12 and 15 days in the PAHs-containing media. Degradation of PAHs, as measured by reversed-phase HPLC on a C18 column, varied with each strain as did the ligninolytic enzymes present in the culture supernatants. Highest degradation of naphthalene (69%) was produced by the strain 984, having Mn-peroxidase activity, followed by strain 870 (17%) showing lignin peroxidase and laccase activities. The greatest degradation of phenanthrene (12%) was observed with strain 870 containing Mn-peroxidase and laccase activities. When anthracene was used, the strain 710 produced a good level of degradation (65%).
Prognosis and Outcome Predictors in Psychogenic Nonepileptic Seizures
Joseph Durrant,Hugh Rickards,Andrea E. Cavanna
Epilepsy Research and Treatment , 2011, DOI: 10.1155/2011/274736
Abstract: It is estimated that one in five patients referred to specialist epilepsy clinics for refractory seizures have psychogenic nonepileptic seizures (PNES). Despite the high prevalence, little is known about the prognosis of patients with PNES. In this paper we set out to systematically assess published original studies on the prognosis and outcome predictors of patients with PNES. Our literature search across the databases Medline, PsycINFO, and EMBASE generated 18 original studies meeting the search criteria. Prognosis was found to be poor in adults, but good in children. Predictors of poor outcome included the presence of coexisting epilepsy or psychiatric comorbidities, violent seizure phenomenology, dependent lifestyle, and poor relationships. Overall, too much reliance is placed on seizure remission as an outcome measurement for patients with PNES, and the impact of many of the outcome predictors requires evaluation using larger studies with longer followup. 1. Introduction Psychogenic nonepileptic seizures (PNESs) are paroxysmal changes in behavior resembling epileptic seizures, in the absence of electrophysiological brain correlates. Time-limited changes in behavioral, motor, sensory, cognitive, and emotional function are all common features, with observers and clinicians often mistaking the condition for epilepsy. PNESs are often considered to be physical manifestations of underlying psychological stressors, despite being perceived as involuntary [1, 2]. PNESs have an incidence of 1.4/100,000 people per year [3], but it is estimated that about 20% of the patients referred to tertiary care epilepsy centers for refractory seizures have this condition [4], making it an important issue in this context. Patients with PNES are often misdiagnosed with epilepsy and treated with antiepileptic drugs (AEDs) for a number of years, resulting in unnecessary exposure to AEDs’ side effects. Patients with PNES can also be offered invasive procedures on the assumption that their seizures are manifestations of an underlying treatment-refractory epileptic disorder [5]. Because of these problems, clinical research on patients with PNES has mainly focussed on the differential diagnosis with epilepsy, somewhat neglecting the question of long-term outcome, which is essential for the optimization of therapeutic resources for this patient population. This paper is aimed at systematically assessing the scientific literature on the prognosis of PNES, in order to identify the most reliable outcome predictors. 2. Methods A systematic literature search was conducted on the
The evolution of policy making within a local education authority
John Durrant
Educate~ , 2006,
Abstract: Contextualisation This paper summarises the progress as at the summer of 2001 of the research for my thesis for the Ed D. The paper is divided into four main sections. First, the location of the research; secondly, identification of issues concerning methodology; thirdly, the preliminary presentation of some tentative results; and finally some initial conclusions from the research.
The role of electron localization in density functionals
M. J. P. Hodgson,J. D. Ramsden,T. R. Durrant,R. W. Godby
Physics , 2014, DOI: 10.1103/PhysRevB.90.241107
Abstract: We introduce a new functional for simulating ground-state and time-dependent electronic systems within density-functional theory. The functional combines an expression for the exact Kohn-Sham (KS) potential in the limit of complete electron localization with a measure of the actual localization. We find accurate self-consistent charge densities, even for systems where the exact exchange-correlation potential exhibits non-local dependence on the density, such as potential steps. We compare our results to the exact KS potential for each system. The self-interaction correction is accurately described, avoiding the need for orbital-dependent potentials.
Electron localization in static and time-dependent systems
T. R. Durrant,M. J. P. Hodgson,J. D. Ramsden,R. W. Godby
Physics , 2015,
Abstract: Electron localization is the tendency of an electron in a many-body system to exclude other electrons from its vicinity. Using a new natural measure of localization based on the exact manyelectron wavefunction, we find that localization can vary considerably between different ground-state systems, and can also be strongly disrupted, as a function of time, when a system is driven by an applied electric field. We use our new measure to assess the well-known electron localization function (ELF), both in its approximate single-particle form (often applied within density-functional theory) and its full many-particle form. The full ELF always gives an excellent description of localization, but the approximate ELF fails in time-dependent situations, even when the exact Kohn-Sham orbitals are employed.
Purification of alpha-galactosidase from seeds of Sesbania marginata
Falco, A.L.P.;Durrant, L.R.;Franco, T.T.;
Brazilian Journal of Chemical Engineering , 2000, DOI: 10.1590/S0104-66322000000400044
Abstract: alpha-galactosidase taken from a raw extract of sesbania marginata legume seeds was purified by partitioning in aqueous two-phase systems (atps). initially, galactomannan/dextran 2,000,000 systems were used for the purification, and the partition coefficients of a -galactosidase varied from 1.5 to 4.0. however, mass transport in these systems was poor due to the high viscosity of the employed polymers. therefore, partitioning in polyethyleneglycol (peg)/ sodium phosphate systems and the effect of sodium chloride upon the enzyme purification and the yield of a -galactosidase were also investigated. the purification achieved in a single-step was 5.7 with a recovery of 144% of a -galactosidase, possibly due to the removal of materials which inhibited a -galactosidase activity before the purification. the removal of the main protein contaminants and the highest yields were achieved in peg 4,000/ sodium phosphate + 6% nacl system at ph 5.0. further purification by preparative on-exchange chromatography was also developed.
Quantitative analysis of Terminal Restriction Fragment Length Polymorphism (T-RFLP) microbial community profiles: peak height data showed to be more reproducible than peak area
Caffaro-Filho, Roberto A.;Fantinatti-Garboggini, Fabiana;Durrant, Lucia R.;
Brazilian Journal of Microbiology , 2007, DOI: 10.1590/S1517-83822007000400027
Abstract: terminal restriction fragment length polymorphism (t-rflp) is a culture-independent fingerprinting method for microbial community analysis. profiles generated by an automated electrophoresis system can be analysed quantitatively using either peak height or peak area data. statistical testing demontrated that peak height data showed to be more reproducible than peak area data.
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