Search results for "Kinetic"
showing 10 items of 3064 documents
Contribution of CYP3A5 to the in vitro hepatic clearance of tacrolimus.
2005
Abstract Background: Tacrolimus is metabolized predominantly to 13-O-demethyltacrolimus in the liver and intestine by cytochrome P450 3A (CYP3A). Patients with high concentrations of CYP3A5, a CYP3A isoenzyme polymorphically produced in these organs, require higher doses of tacrolimus, but the exact mechanism of this association is unknown. Methods: cDNA-expressed CYP3A enzymes and a bank of human liver microsomes with known CYP3A4 and CYP3A5 content were used to investigate the contribution of CYP3A5 to the metabolism of tacrolimus to 13-O-demethyltacrolimus as quantified by liquid chromatography–tandem mass spectrometry. Results: Demethylation of tacrolimus to 13-O-demethyltacrolimus was …
Identification of the mstE Gene Encoding a Glucose-inducible, Low Affinity Glucose Transporter in Aspergillus nidulans
2006
The mstE gene encoding a low affinity glucose transporter active during the germination of Aspergillus nidulans conidia on glucose medium has been identified. mstE expression also occurs in hyphae, is induced in the presence of other repressing carbon sources besides glucose, and is dependent on the function of the transcriptional repressor CreA. The expression of MstE and its subcellular distribution have been studied using a MstE-sGFP fusion protein. Concordant with data on mstE expression, MstE-sGFP is synthesized in the presence of repressing carbon sources, and fluorescence at the periphery of conidia and hyphae is consistent with MstE location in the plasma membrane. Deletion of mstE …
Overexpression and functional characterization of kinin receptors reveal subtype-specific phosphorylation.
1999
G protein-coupled receptors such as the receptors for bradykinin are present in low copy numbers in most natural cells. To overcome the problems associated with the analysis of these receptors at the protein level, we used highly efficient expression systems such as the baculovirus/insect cell system. However, the structural and functional statuses of recombinant receptors have often remained elusive. We have expressed the two types of human kinin receptors, B1 and B2, in Sf9 cells. Both receptors are found on the surface of infected cells where they display the same pharmacological profiles as their cognate receptors of native cells. The functional analysis of kinin receptors coupled to th…
Arbutin synthase, a novel member of the NRD1β glycosyltransferase family, is a unique multifunctional enzyme converting various natural products and …
2002
Plant glucosyltransferases (GTs) play a crucial role in natural product biosynthesis and metabolization of xenobiotics. We expressed the arbutin synthase (AS) cDNA from Rauvolfia serpentina cell suspension cultures in Escherichia coli with a 6 x His tag and purified the active enzyme to homogeneity. The recombinant enzyme had a temperature optimum of 50 degrees C and showed two different pH optima (4.5 and 6.8 or 7.5, depending on the buffer). Out of 74 natural and synthetic phenols and two cinnamyl alcohols tested as substrates for the AS, 45 were accepted, covering a broad range of structural features. Converting rates comparable to hydroquinone were not achieved. In contrast to this broa…
Hirālu piridīna organokatalizatoru izstrāde un pielietojums
2015
Maģistra darba ietvaros tika izstrādāta hirālu DMAP organokatalizatoru sintēze. Iegūto organokatalizatoru aktivitāte tika pārbaudīta tetrazola hemiaminālu dinamiskajā kinētiskajā sadalīšanā.
Transglutaminase and polyamine dependence of effector functions of human immunocompetent cells
1982
AbstractThe effects of the transglutaminase inhibitor dansyl cadaverine (DC) and the polyamine antagonist methyl glyoxal-bis-(guanylhydrazone) (MeGbG) on the response of lymphocytes towards allogeneic and lectin stimulation and on the zymosan-induced chemiluminescence of neutrophilic granulocytes was studied. Application of DC resulted in dose-dependent suppression of chemiluminiscence and lymphocyte proliferation; no difference of inhibitory potential occurred with variation of incubation time in the latter system. MeGbG was inactive in granulocytes, but inhibited lymphocyte proliferation; its effect increased with time. The experiments provide further evidence for the importance of transg…
Micellar electrokinetic chromatography with bile salts for predicting ecotoxicity of aromatic compounds.
2004
The retention factors of several aromatic compounds were obtained by micellar electrokinetic chromatography (MEKC) using cholate, taurocholate, deoxycholate and deoxytaurocholate as micellar systems. The possibility of using these retention factors to describe and predict several ecotoxicological activities of different aromatic compounds was evaluated. Adequate correlations retention–ecotoxicity (log LC50 in fish and daphnia, log EC50 in green algae and daphnia, chronic values in fish and green algae, bioconcentration factor, and soil sorption coefficient) were obtained for the micellar systems studied. The predictive ability of the models obtained for these micellar systems was compared. …
IMI – Oral biopharmaceutics tools project – Evaluation of bottom-up PBPK prediction success part 4: Prediction accuracy and software comparisons with…
2020
Oral drug absorption is a complex process depending on many factors, including the physicochemical properties of the drug, formulation characteristics and their interplay with gastrointestinal physiology and biology. Physiological-based pharmacokinetic (PBPK) models integrate all available information on gastro-intestinal system with drug and formulation data to predict oral drug absorption. The latter together with in vitro-in vivo extrapolation and other preclinical data on drug disposition can be used to predict plasma concentration-time profiles in silico. Despite recent successes of PBPK in many areas of drug development, an improvement in their utility for evaluating oral absorption i…
Supramolecular Eutecto Gels: Fully Natural Soft Materials
2018
The obtainment of materials featured by high environmental compatibility is one of the main goals of modern research. On this subject, we herein report the first example of supramolecular gel in deep eutectic solvents. In particular, we prepared gels of the L-amino acids isoleucine and tryptophan in choline chloride/phenylacetic acid 1:2. All gel components are readily available and nontoxic. Gels have been fully characterized by standard gelation tests, rheology, X-ray diffraction, morphology and gelation kinetics. Data collected show that gels properties depend on the gelator nature. In particular, gel phases exhibit strong colloidal forces and, this high mechanical resistance, together w…
Endocrine disrupter compounds removal in wastewater using microalgae: Degradation kinetics assessment
2018
[EN] This paper describes a study carried out to determine the removal kinetics of four micropollutants (4-tert-octylphenol (OP), technical-nonylphenol (t-NP), 4-nonylphenol (4-NP) and bisphenol-A (BPA)) usually found in wastewater streams. The kinetic experiments were carried out in batch reactors containing the effluent of an Anaerobic Membrane BioReactor (AnMBR) in the presence of light, oxygen and microalgae. As the degradation process of the studied micropollutants obeyed a pseudo-first-order kinetics, the second-order kinetics for each micropollutant was then calculated. The second order rate constants for the hydroxyl radical (k.(OH)) ranged from 7.0.10(+10) to 6.6.10(+12) L.mol(-1).…