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Find video protocols related to scientific articles indexed in Pubmed.
Reducing the mobility of arsenic in brownfield soil using stabilised zero-valent iron nanoparticles.
J Environ Sci Health A Tox Hazard Subst Environ Eng
PUBLISHED: 07-30-2014
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The use of nanoscale zero-valent iron (nZVI) as a new tool for the treatment of polluted soils and groundwater has received considerable attention in recent years due to its high reactivity, in situ application and cost-effectiveness. The objectives of this study were to investigate the effectiveness of using a commercial stabilised suspension of nZVI to immobilise As in brownfield soil and to investigate its impact on Fe availability in the treated soil. The phytotoxicities of the soil samples were also evaluated using a germination test with two plant species: barley (Hordeum vulgare L) and common vetch (Vicia sativa L). Two doses of the commercial nZVI suspension were studied, 1% and 10%, and two soil-nanoparticle interaction times, 72 h and 3 mo, were used to compare the stabilities of the soils treated with nZVI. The As availability was evaluated using a sequential extraction procedure and the toxicity characteristics leaching procedure (TCLP) test. The application of nZVI significantly decreased the availability of As in the soil. The immobilisation of As was more effective and more stable over time with the 10% dose than with the 1% dose of the commercial nZVI suspension. The application of nZVI did not induce an important increase in Fe mobility because the Fe leachability was less than 2 mg L(-1) over the time period studied. The lower availability of As in the soil led to a decrease in the phytotoxicity of the soil to barley and vetch germination. Thus, the proposed nanotechnology could be a potential alternative for the in situ remediation of As-polluted soils and could be combined with remediation processes where plants are involved.
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Can parent training for parents with high levels of expressed emotion have a positive effect on their child's social anxiety improvement?
J Anxiety Disord
PUBLISHED: 05-28-2014
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The role that parents' involvement may play in improving their child's social anxiety is still under debate. This paper aimed to investigate whether training parents with high expressed emotion (EE) could improve outcomes for adolescent social anxiety intervention. Fifty-two socially anxious adolescents (aged 13-18 years), whose parents exhibited high levels of expressed emotion, were assigned to either (a) a school-based intervention with an added parent training component, or (b) a school-based program focused solely on intervening with the adolescent (no parental involvement). Post-treatment and 12-month follow-up findings showed that school-based intervention with parent training was superior to the adolescent-specific program, yielding significant reductions in diagnosis remission, social and depressive symptomatology, particularly when the EE status of parents changed. Overall, the findings suggest that high-EE parents of children with social anxiety need to be involved in their child's therapy.
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Chemo-, regio-, and stereoselective silver-catalyzed aziridination of dienes: scope, mechanistic studies, and ring-opening reactions.
J. Am. Chem. Soc.
PUBLISHED: 03-28-2014
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Silver complexes bearing trispyrazolylborate ligands (Tp(x)) catalyze the aziridination of 2,4-diene-1-ols in a chemo-, regio-, and stereoselective manner to give vinylaziridines in high yields by means of the metal-mediated transfer of NTs (Ts = p-toluensulfonyl) units from PhI?NTs. The preferential aziridination occurs at the double bond neighboring to the hydroxyl end in ca. 9:1 ratios that assessed a very high degree of regioselectivity. The reaction with the silver-based catalysts proceeds in a stereospecific manner, i.e., the initial configuration of the C?C bond is maintained in the aziridine product (cis or trans). The degree of regioselectivity was explained with the aid of DFT studies, where the directing effect of the OH group of 2,4-diene-1-ols plays a key role. Effective strategies for ring-opening of the new aziridines, deprotection of the Ts group, and subsequent formation of ?-amino alcohols have also been developed.
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THDP17 Decreases Ammonia Production through Glutaminase Inhibition. A New Drug for Hepatic Encephalopathy Therapy.
PLoS ONE
PUBLISHED: 01-01-2014
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Ammonia production is implicated in the pathogenesis of hepatic encephalopathy (HE), being intestinal glutaminase activity the main source for ammonia. Management of ammonia formation can be effective in HE treatment by lowering intestinal ammonia production. The use of glutaminase inhibitors represents one way to achieve this goal. In this work, we have performed a search for specific inhibitors that could decrease glutaminase activity by screening two different groups of compounds: i) a group integrated by a diverse, highly pure small molecule compounds derived from thiourea ranging from 200 to 800 Daltons; and ii) a group integrated by commonly use compounds in the treatment of HE. Results shown that THDP-17 (10 µM), a thiourea derivate product, could inhibit the intestinal glutaminase activity (57.4±6.7%). Inhibitory effect was tissue dependent, ranging from 40±5.5% to 80±7.8% in an uncompetitive manner, showing Vmax and Km values of 384.62 µmol min-1, 13.62 mM with THDP-17 10 µM, respectively. This compound also decreased the glutaminase activity in Caco-2 cell cultures, showing a reduction of ammonia and glutamate production, compared to control cultures. Therefore, the THDP-17 compound could be a good candidate for HE management, by lowering ammonia production.
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Psychometric properties of the screen for child anxiety related emotional disorders for socially anxious and healthy spanish adolescents.
Span J Psychol
PUBLISHED: 07-20-2013
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Socially anxious and healthy Spanish adolescents were studied in order to test the psychometric properties of the Screen for Child Anxiety Related Emotional Disorders (SCARED). Confirmatory factor analyses were employed to test measurement invariance between these two populations, Cronbachs alphas were calculated to determine the reliabilities of the scales, and partial eta-square tests calculated the effect size of the differences between socially anxious and healthy adolescents and between the adolescent boys and girls. The psychometric properties of the SCARED were good, as demonstrated by having acceptable reliabilities (ranging from .75 - .41) and a moderate multivariate effect size (? p 2 = .08) between the adolescent boys and girls. Most importantly, it was demonstrated that the SCARED could differentiate between socially anxious and healthy Spanish adolescents as demonstrated by measurement invariance (? 2 = 254.27, df = 1343, GFI = .884, AGFI = .872, RMR = .031) and the large effect size (? p 2 = .22) between the samples.
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Introducing copper as catalyst for oxidative alkane dehydrogenation.
J. Am. Chem. Soc.
PUBLISHED: 03-04-2013
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The dehydrogenation of n-hexane and cycloalkanes giving n-hexene and cycloalkenes has been observed in the reaction of such hydrocarbons with hydrogen peroxide, in the presence of copper complexes bearing trispyrazolylborate ligands. This catalytic transformation provides the typical oxidation products (alcohol and ketones) with small amounts of the alkenes, a novel feature in this kind of oxidative processes. Experimental data exclude the participation of hydroxyl radicals derived from Fenton-like reaction mechanisms. DFT studies support a copper-oxo active species, which initiates the reaction by H abstraction. Spin crossover from the triplet to the singlet state, which is required to recover the catalyst, yields the major hydroxylation and minor dehydrogenation products. Further calculations suggested that the superoxo and hydroperoxo species are less reactive than the oxo. A complete mechanistic proposal in agreement with all experimental and computational data is proposed.
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A general mechanism for the copper- and silver-catalyzed olefin aziridination reactions: concomitant involvement of the singlet and triplet pathways.
J. Am. Chem. Soc.
PUBLISHED: 01-22-2013
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The olefin aziridination reactions catalyzed by copper and silver complexes bearing hydrotris(pyrazolyl)borate (Tp(x)) ligands have been investigated from a mechanistic point of view. Several mechanistic probe reactions were carried out, specifically competition experiments with p-substituted styrenes, stereospecificity of olefins, effects of the radical inhibitors, and use of a radical clock. Data from these experiments seem to be contradictory, as they do not fully support the previously reported concerted or stepwise mechanisms. But theoretical calculations have provided the reaction profiles for both the silver and copper systems with different olefins to satisfy all experimental data. A mechanistic proposal has been made on the basis of the information that we collected from experimental and theoretical studies. In all cases, the reaction starts with the formation of a metal-nitrene species that holds some radical character, and therefore the aziridination reaction proceeds through the radical mechanism. The silver-based systems however hold a minimum energy crossing point (MECP) between the triplet and closed-shell singlet surfaces, which induce the direct formation of the aziridines, and stereochemistry of the olefin is retained. In the case of copper, a radical intermediate is formed, and this intermediate constitutes the starting point for competition steps involving ring-closure (through a MECP between the open-shell singlet and triplet surfaces) or carbon-carbon bond rotation, and explains the loss of stereochemistry with a given substrate. Overall, all the initially contradictory experimental data fit in a mechanistic proposal that involves both the singlet and the triplet pathways.
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Catalytic cross-coupling of diazo compounds with coinage metal-based catalysts: an experimental and theoretical study.
Dalton Trans
PUBLISHED: 01-19-2013
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We examined the ability of Tp(x)M (Tp(x) = hydrotris(pyrazolyl)borate ligand; M = Cu and Ag) and IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene; M = Cu, Ag, Au) complexes as catalyst precursors for the cross-coupling of diazo compounds. Experimental data showed that the metal centre can be tuned with the appropriate selection of the ligand to yield either the homo- or hetero-coupling (cross-coupling) products. A computational study of the reaction mechanism allowed the rationalization of the experimental reactivity patterns, and the identification of the key reaction step controlling the selectivity: the initial reaction between the metallocarbene intermediate and one of the diazo compounds.
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Potential diffusion of doramectin into a soil amended with female pig manure. A field experiment.
J. Agric. Food Chem.
PUBLISHED: 09-09-2011
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Doramectin is a veterinary drug used as an antihelminthic and is excreted mainly in the feces as the nonmetabolized drug. This study investigated the time profile of doramectin excretion in pig feces and the potential transfer and persistence of doramectin in the soil when the pig manure is used as an organic amendment to the soil. The concentration of doramectin in feces peaked at 143.0 ng/g in the dry feces 4 days after treatment. On day 62, the drug was still detected in the pig feces. After the land application of pig manure, the maximum concentration of doramectin in soil (ppb level) was detected 6 days after treatment. Seven months after the manure application, traces of doramectin were detected in the soil from the surface to a depth of 90 cm. Successive applications of manure from pigs treated with doramectin in a specific area could produce an accumulation of this drug in the soil.
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Two-step oxidation of glycerol to glyceric acid catalyzed by the Phanerochaete chrysosporium glyoxal oxidase.
Enzyme Microb. Technol.
PUBLISHED: 08-29-2011
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Glyoxal oxidase of P. chrysosporium is a radical copper oxidase that catalyzes oxidation of aldehydes to carboxylic acids coupled to dioxygen reduction to H(2)O(2). In addition to known substrates, glycerol is also found to be a substrate for glyoxal oxidase. During enzyme turnover, glyoxal oxidase undergoes a reversible inactivation, probably caused by loss of the active site free radical, resulting in short-lasting enzyme activities and undetectable substrate conversions. Enzyme activity could be extended by including two additional enzymes, horseradish peroxidase and catalase, in addition to a redox chemical activator, such as Mn(III) (or Mn(II)+H(2)O(2)) or hexachloroiridate. Using this three-enzyme system glycerol was converted in glyceric acid in a two-step reaction, with glyceraldehyde as intermediate. A possible operation mechanism is proposed in which the three enzymes would work coordinately allowing to maintain a sustained glyoxal oxidase activity. In the course of its catalytic cycle, glyoxal oxidase alternates between two functional and interconvertible reduced and oxidized forms resulting from a two-electron transfer process. However, glyoxal oxidase can also undergo an one-electron reduction to a catalytically inactive form lacking the active site free radical. Horseradish peroxidase could use glyoxal oxidase-generated H(2)O(2) to oxidize Mn(II) to Mn(III) which, in turn, would reoxidize and reactivate the inactive form of glyoxal oxidase. Catalase would remove the excess of H(2)O(2) generated during the reaction. In spite of the improvement achieved using the three-enzyme system, glyoxal oxidase inactivation still occurred, which resulted in low substrate conversions. Possible causes of inactivation, including end-product inhibition, are discussed.
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[The prognosis for children of mothers with preeclampsia. Part 2: long-term effects].
Arch Argent Pediatr
PUBLISHED: 08-15-2011
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Preeclampsia affects between 4% to 8% of all human pregnancies. It compromised both mothers and offspring beyond perinatal period. This is the second of two papers devoted to show the available evidence about the effect of preeclampsia on offsprings beyond perinatal period from cohort studies, some over 60-years follow-up. From this perspective, these children are at great risk to develop cardiovascular disorders as hypertension, as well as other disorders, as cancer or neuropsychiatric ones.
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[The prognosis for children of mothers with preeclampsia. Part 1: short-term effects].
Arch Argent Pediatr
PUBLISHED: 08-15-2011
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Preeclampsia affects between 4 to 8% of all human pregnancies. It compromised both mothers and offspring beyond perinatal period. This is the first o two papers related whit this phenomenon and shows the available evidence about the effect of preeclampsia over the preeclamptic offspring from cohort studies. It is devoted to develop all facts related with respiratory distress syndrome, sepsis, neurological issues and other problems presented over neonatal period.
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Direct, copper-catalyzed oxidation of aromatic C-H bonds with hydrogen peroxide under acid-free conditions.
Chem. Commun. (Camb.)
PUBLISHED: 06-16-2011
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The direct oxidation of benzene into phenol using hydrogen peroxide has been achieved in the absence of any acid with Tp(x)Cu(NCMe) complexes as the catalysts. In the case of anthracenes as the substrates, valuable anthraquinones have been quantitatively obtained in the same manner.
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Silver-catalyzed C-C bond formation between methane and ethyl diazoacetate in supercritical CO?.
Science
PUBLISHED: 05-14-2011
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Even in the context of hydrocarbons general resistance to selective functionalization, methanes volatility and strong bonds pose a particular challenge. We report here that silver complexes bearing perfluorinated indazolylborate ligands catalyze the reaction of methane (CH(4)) with ethyl diazoacetate (N(2)CHCO(2)Et) to yield ethyl propionate (CH(3)CH(2)CO(2)Et). The use of supercritical carbon dioxide (scCO(2)) as the solvent is key to the reactions success. Although the catalyst is only sparingly soluble in CH(4)/CO(2) mixtures, optimized conditions presently result in a 19% yield of ethyl propionate (based on starting quantity of the diazoester) at 40°C over 14 hours.
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Gold-catalyzed naphthalene functionalization.
Beilstein J Org Chem
PUBLISHED: 03-31-2011
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The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene, M = Cu, 1a; M = Au, 1b), in the presence of one equiv of NaBAr(4) (Ar = 3,5-bis(trifluoromethyl)phenyl), catalyze the transfer of carbene groups: C(R)CO(2)Et (R = H, Me) from N(2)C(R)CO(2)Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C-H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed.
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Brain biomolecules oxidation in portacaval-shunted rats.
Liver Int.
PUBLISHED: 03-29-2011
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Oxidative stress induced by a high ammonia concentration has been suggested to be implicated in the pathophysiology of hepatic encephalopathy (HE). Therefore, oxidative damage of brain biomolecules could contribute towards explaining the neurological and motor alterations observed in HE.
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Mercury uptake by Silene vulgaris grown on contaminated spiked soils.
J. Environ. Manage.
PUBLISHED: 04-07-2010
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Mercury is a highly toxic pollutant with expensive clean up, because of its accumulative and persistent character in the biota. The objective of this work was to evaluate the effectiveness of Silene vulgaris, facultative metallophyte which have populations on both non-contaminated and metalliferous soils, to uptake Hg from artificially polluted soils. A pot experiment was carried out in a rain shelter for a full growth period. Two soils (C pH = 8.55 O.M. 0.63% and A pH = 7.07 O.M. 0.16%) were used, previously contaminated with Hg as HgCl(2) (0.6 and 5.5 mg Hg kg(-1) soil). Plants grew healthy and showed good appearance throughout the study without significantly decreasing biomass production. Mercury uptake by plants increased with the mercury concentration found in both soils. Differences were statistically significant between high dosage and untreated soil. The fact that S. vulgaris retains more mercury in root than in shoot and also, the well known effectiveness of these plants in the recovering of contaminated soils makes S. vulgaris a good candidate to phytostabilization technologies.
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Selective synthesis of N-substituted 1,2-dihydropyridines from furans by copper-induced concurrent tandem catalysis.
J. Am. Chem. Soc.
PUBLISHED: 03-17-2010
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A novel transformation in which mono- or dialkyl-substituted furans are converted into 1,2-dihydropyridines upon reaction with PhI horizontal lineNTs at room temperature is reported. The reaction is catalyzed by complexes of general formula Tp(x)M (M = Cu, Ag) and consists of a one-pot procedure with four consecutive catalytic cycles. Furan aziridination is followed by aziridine ring-opening, transimination reaction, inverse-electronic-demand aza-Diels-Alder reaction, and a final hydrogen elimination reaction. The mechanism of the overall transformation is proposed where the metal complex displays a crucial role along the reaction pathway.
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Evaluation of wine aromatic compounds by a sensory human panel and an electronic nose.
J. Agric. Food Chem.
PUBLISHED: 11-19-2009
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A comparative study between the perception and recognition thresholds of volatile components calculated for an electronic nose and a human sensory panel is presented. The electronic nose is home-developed for wine purposes and is based on thin film semiconductor sensors. The human sensory panel is formed by 25 tasters with previous experience in wine tasting. Both systems were trained in parallel to detect 17 volatile compounds involved in aromatic and off-flavor notes (grouped under 9 aromatic descriptors) from the threshold concentrations found in the literature (T) to increasing concentrations (T, 2T, and 4T). The results showed that the perception level of the human nose is superior in relation to the electronic nose, but the electronic nose gave better results in the recognition threshold of the some aroma. According to these results, it can be concluded that the electronic nose could be a useful complementary tool to sensory human panels.
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Exploring the relevance of expressed emotion to the treatment of social anxiety disorder in adolescence.
J Adolesc
PUBLISHED: 08-10-2009
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The role that the involvement of parents may play in the treatment outcome of their children with anxiety disorders is still under debate. Some studies dealing with other disorders have examined the role that the expressed emotion (EE) construct (parental overinvolvement, criticism and hostility) may play in treatment outcome and relapse. Given that some of these aspects have been associated with social anxiety for a long time, it was hypothesized that EE may be associated with lower treatment outcome. The sample was composed of 16 adolescents who benefited from a school-based, cognitive-behavioural intervention aimed at overcoming social anxiety. Then, parents were classified with high or low EE. The results revealed that the adolescents whose parents had low EE showed a statistically significant reduction of their social anxiety scores at posttest, as opposed to adolescents of parents with high expressed emotion. These findings suggest that parental psychopathology (parents with high EE) should be taken into consideration to prevent poor adolescent treatment outcome.
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Highly active gold-based catalyst for the reaction of benzaldehyde with ethyl diazoacetate.
Chem. Commun. (Camb.)
PUBLISHED: 07-16-2009
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The gold complex [IPrAu(NCMe)]BF(4) catalyzes the reaction of ethyl diazoacetate with benzaldehyde to give mixtures of ethyl 3-oxo-3-phenylpropanoate and ethyl 3-hydroxy-2-phenylacrylate in the first example of a group 11 metal-based catalyst for this transformation; the catalyst activity is improved by a factor of 2500 compared to those of previously reported iron-based catalysts.
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The selective catalytic formation of beta-boryl aldehydes through a base-free approach.
Org. Biomol. Chem.
PUBLISHED: 03-11-2009
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(NHC)Cu(I) complexes are key in a new strategy to selectively add a boron unit at the beta-position of alpha,beta-unsaturated aldehydes in the absence of a base.
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Role of diabetes mellitus on hepatic encephalopathy.
Metab Brain Dis
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Hepatic encephalopathy is the main cognitive dysfunction in cirrhotic patients associated with impaired prognosis. Hyperammonemia plus inflammatory response do play a crucial role on hepatic encephalopathy. However, in some patients HE appeared without hyperammonemia and patients with increased levels of ammonia could not show cognitive dysfunction. This has led to investigate other factors that could act in a synergistic way. Diabetes mellitus and insulin resistance are characterized by releasing and enhancing these pro-inflammatory cytokines and, additionally, has been related to hepatic encephalopathy. Indeed, patients with diabetes showed raised risk of over hepatic encephalopathy in comparison with non-cirrhotics. Type 2 diabetes mellitus could impair hepatic encephalopathy by different mechanisms that include: a) increasing glutaminase activity; b) impairing gut motility and promoting constipation, intestinal bacterial overgrowth and bacterial translocation. Despite of insufficient clarity about the practicability of anti-diabetic therapy and the most efficacious therapy, we would have to pay a special attention to the management of type 2 diabetes mellitus and insulin resistance in cirrhotic patients.
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Metformin inhibits glutaminase activity and protects against hepatic encephalopathy.
PLoS ONE
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To investigate the influence of metformin use on liver dysfunction and hepatic encephalopathy in a retrospective cohort of diabetic cirrhotic patients. To analyze the impact of metformin on glutaminase activity and ammonia production in vitro.
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Selective intentional forgetting in adolescents with social anxiety disorder.
Psychiatry Res
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Anxiety in young adults has recently been linked to reduced capacities to inhibit the processing of non-affective perceptual distractors. However, no previous research has addressed the relationship between social anxiety disorder (SAD) and the ability to intentionally inhibit no longer relevant memories. In an experimental study with adolescents diagnosed with SAD and matched nonclinical controls, a selective directed forgetting procedure was used to assess the extent to which anxious individuals showed lower memory impairment for to-be-forgotten information than their non-anxious counterparts. The results revealed that while the nonclinical sample group demonstrated the ability to selectively forget when instructed, the anxious adolescents demonstrated good memory for to-be-forgotten material and therefore failed to forget. Interestingly, more severe SAD symptomatology inversely predicted a degree of forgetting. We conclude that the main difference between socially anxious and non-anxious participants is specifically related to the ability to intentionally forget and could reflect cognitive functioning that is associated with vulnerability to anxiety. Impairment of the ability to make unwanted memories less retrievable could prompt some individuals to initiate or maintain anxiety disorders. Future psychological treatments could benefit from including modules on memory control training.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.