Search results for " Inhibition"
showing 10 items of 435 documents
Author response: ON selectivity in the Drosophila visual system is a multisynaptic process involving both glutamatergic and GABAergic inhibition
2019
A computational approach for the assessment of executive functions in patients with obsessive-compulsive disorder
2019
Previous studies on obsessive–compulsive disorder (OCD) showed impairments in executive domains, particularly in cognitive inhibition. In this perspective, the use of virtual reality showed huge potential in the assessment of executive functions; however, unfortunately, to date, no study on the assessment of these patients took advantage of the use of virtual environments. One of the main problems faced within assessment protocols is the use of a limited number of variables and tools when tailoring a personalized program. The main aim of this study was to provide a heuristic decision tree for the future development of tailored assessment protocols. To this purpose, we conducted a study that…
Considering syntrophic acetate oxidation and ionic strength improves the performance of models for food waste anaerobic digestion.
2021
Current mechanistic anaerobic digestion (AD) models cannot accurately represent the underlying processes occurring during food waste (FW) AD. This work presents an update of the Anaerobic Digestion Model no. 1 (ADM1) to provide accurate estimations of free ammonia concentrations and related inhibition thresholds, and model syntrophic acetate oxidation as acetate-consuming pathway. A modified Davies equation predicted NH3 concentrations and pH more accurately, and better estimated associated inhibitory limits. Sensitivity analysis results showed the importance of accurate disintegration kinetics and volumetric mass transfer coefficients, as well as volatile fatty acids (VFAs) and hydrogen up…
Metabolic signatures across the full spectrum of non-alcoholic fatty liver disease.
2022
Funder: European Commission
Influence of gamma-aminobutyric acid on baclofen intestinal absorption.
1994
Since previous studies suggested that baclofen absorption in the rat middle intestine was inhibited by beta-alanine and therefore mediated, at least in part, by the beta-aminoacid carrier, we focused our new studies on the analysis of the possible inhibition of the drug by a gamma-aminoacid model compound, gamma-aminobutyric acid (GABA). A rat jejunum in situ study was undertaken in order to evaluate the effect of GABA on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen with starting GABA concentrations ranging from 0 to 100 mM are reported. The results show that the absorption rate pseudoconstants of the drug decrease a…
Partially competitive inhibition of intestinal baclofen absorption by beta-alanine, a nonessential dietary aminoacid.
1991
In situ intestinal absorption of baclofen in the rat in the presence of beta-alanine has been investigated. Through the perfusion of 0.50 mM baclofen solutions containing variable concentrations of the aminoacid (from 5 to 100 mM), a partially competitive inhibition of baclofen absorption was characterized: absorption rate pseudoconstants of the spasmolytic drug decrease as beta-alanine concentration increases, until a limiting value is obtained (36.8 per cent of that found for baclofen alone). A computer method was developed in order to calculate parameters governing baclofen absorption in the presence of beta-aminoacid, with the following results: Vm = 11.22 mM h-1; Km = 7.42 mM; Ki = 2.4…
Intestinal absorption pathway of gamma-aminobutyric acid in rat small intestine.
1994
Intestinal absorption of gamma-aminobutyric acid (GABA), as a model compound for gamma-aminoacids, has not been extensively studied from the kinetic viewpoint. Since data from our laboratory suggested that some competition arises between intestinal absorption of beta-alanine and GABA and since our intent was to maintain the aqueous stagnant diffusion layer in order to approach absorption tests to in vivo physiological conditions, a rat jejunum in situ study was undertaken in order to gain an insight into the mechanism of GABA absorption. In the present paper, results from assays using isotonic perfusion solutions with starting GABA concentrations ranging from 1 to 50 mM are reported. They s…
Evidence of competitive inhibition for the intestinal absorption of baclofen by phenylalanine
1996
Abstract Previous studies showed that the absorption of the antispastic drug baclofen, in the rat middle intestine, is inhibited by β-alanine, γ-aminobutyric acid (GABA) and leucine. It was concluded that baclofen intestinal transport was mediated, at least in part, by the β-, γ- and α-amino acid carriers. We therefore focused our next studies on the analysis of the possible inhibition of drug absorption by an aromatic α-amino acid model compound, phenylalanine. An in situ study in the rat small intestine was undertaken in order to evaluate the effect of phenylalanine on baclofen absorption and to establish the inhibition model. Assays using isotonic perfusion solutions of 0.5 mM baclofen w…
Purification and characterization of the catabolic ?-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris
1995
The α-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris was purified to homogeneity in SDS-PAGE. The enzyme is a trimer of 3×55,000 Da. It was unstable but could be preserved by addition of pyruvate and thiamine pyrophosphate in the buffer. The enzyme exhibits Michaelis-Menten kinetics, and Km for pyruvate is 10 mM. Three intermediates in glucose metabolism (ATP, 3-phosphoglycerate, and phosphoenolpyruvate) exhibit a noncompetitive inhibition towards the enzyme. This enzyme does not require any divalent metal ion for activity. The α-acetolactate synthase from Leuconostoc mesenteroides subsp. cremoris is not inhibited by the branched-chain amino acids (valine, leucine, and…
The relation between neuronal chloride transporter activities, GABA inhibition, and neuronal activity
2020
Abstract The intracellular chloride concentration [Cl−]i in neurons is regulated by a set of transmembrane transporters, with the Cl−-loader NKCC1 and the Cl−-extruder KCC2 as most relevant members. The expression of these transporters is tightly regulated, with the general trend that KCC2 expression is low in immature neurons, which are thus characterized by a high [Cl−]i. As [Cl−]i is the main factor determining the polarity of GABAergic responses, such a high [Cl−]i is related to depolarizing GABAergic responses. However, depolarizing GABAergic responses are not per se excitatory, but can also contribute to shunting inhibition. The excitatory/inhibitory action of GABAergic responses is m…