Search results for "Kinetics"
showing 10 items of 2224 documents
rbFOX1/MBNL1 competition for CCUG RNA repeats binding contributes to myotonic dystrophy type 1/type 2 differences
2018
Myotonic dystrophy type 1 and type 2 (DM1, DM2) are caused by expansions of CTG and CCTG repeats, respectively. RNAs containing expanded CUG or CCUG repeats interfere with the metabolism of other RNAs through titration of the Muscleblind-like (MBNL) RNA binding proteins. DM2 follows a more favorable clinical course than DM1, suggesting that specific modifiers may modulate DM severity. Here, we report that the rbFOX1 RNA binding protein binds to expanded CCUG RNA repeats, but not to expanded CUG RNA repeats. Interestingly, rbFOX1 competes with MBNL1 for binding to CCUG expanded repeats and overexpression of rbFOX1 partly releases MBNL1 from sequestration within CCUG RNA foci in DM2 muscle ce…
Kinetic evidence for interaction of TMPyP4 with two different G-quadruplex conformations of human telomeric DNA
2018
Background: Stabilization of G-quadruplex helices by small ligands has attracted growing attention because they inhibit the activity of the enzyme telomerase, which is overexpressed in> 80% cancer cells. TMPyP4, one of the most studied G-quadruplex ligands, is used as a model to show that the ligands can exhibit different binding features with different conformations of a human telomeric specific sequence. Methods: UV–Vis, FRET melting Assay, Isothermal Titration Calorimetry, Time-resolved Fluorescence lifetime, T-Jump and Molecular Dynamics. Results: TMPyP4 yields two different complexes with two Tel22 telomeric conformations in the presence of Na+ or K+. T-Jump kinetic experiments show th…
Molecular docking-based design and development of a highly selective probe substrate for UDP-glucuronosyltransferase 1A10
2018
Intestinal and hepatic glucuronidation by the UDP-glucuronosyltransferases (UGTs) greatly affect the bioavailability of phenolic compounds. UGT1A10 catalyzes glucuronidation reactions in the intestine, but not in the liver. Here, our aim was to develop selective, fluorescent substrates to easily elucidate UGT1A10 function. To this end, homology models were constructed and used to design new substrates, and subsequently, six novel C3-substituted (4-fluorophenyl, 4-hydroxyphenyl, 4-methoxyphenyl, 4-(dimethylamino)phenyl, 4-methylphenyl, or triazole) 7-hydroxycoumarin derivatives were synthesized from inexpensive starting materials. All tested compounds could be glucuronidated to nonfluorescen…
Reactions of Flavonoids with o‑Quinones Interfere with the Spectrophotometric Assay of Tyrosinase Activity
2016
Flavonoids are important food components with antioxidant properties and many of them have been described as tyrosinase inhibitors. Oxidation of quercetin, kaempferol, morin, catechin, and naringenin by mushroom tyrosinase and their influence on the oxidation of l-dopa and l-tyrosine was studied. Reaction rates measured spectrophotometrically and by oxygen consumption differed substantially. All tested flavonoids reacted with 4-tert-butyl-o-benzoquinone and/or 4-methyl-o-benzoquinone, although at different rates. These reactions generated products whose UV-vis spectra either overlapped or did not overlap with the spectrum of dopachrome. They therefore strongly influence the kinetic analysis…
Chemistry, Pharmacodynamics, and Pharmacokinetics of NSAIDs
2016
Numerous chemically different entities are clustered under the label of nonsteroidal anti-inflammatory drugs (NSAIDs). They share the ability to inhibit prostanoid synthesis by blocking the activity of the cyclooxygenase enzymes and, as a consequence, to exert anti-inflammatory, analgesic, and antipyretic effects. On the other hand, by hindering the housekeeping roles of prostaglandins, they also deteriorate the gastrointestinal mucosal barrier and the renal and endothelial hemodynamic regulation. The present chapter compiles available pharmacokinetic and pharmacodynamic data that may help to understand the different therapeutic profiles reported for particular agents.
A phase I study of nintedanib combined with cisplatin/gemcitabine as first-line therapy for advanced squamous non-small cell lung cancer (LUME-Lung 3)
2018
Abstract Background There are limited treatment options for squamous non-small cell lung cancer (sqNSCLC) and prognosis remains poor. The safety and pharmacokinetics (PK) of nintedanib, a triple angiokinase inhibitor, plus cisplatin/gemcitabine as first-line treatment for advanced sqNSCLC patients, were evaluated. Materials and methods A phase I, dose-escalation study administering drugs in a 21-day cycle: cisplatin (75 mg/m2, Day 1), gemcitabine (1250 mg/m2, Days 1 and 8) and nintedanib (Days 2–7, 9–21) were given for 4–6 cycles, followed by monotherapy until disease progression or adverse events (AEs). Two nintedanib doses were tested, 150 mg twice daily (bid) and 200 mg bid, to determine…
Drug Distribution to Retinal Pigment Epithelium: Studies on Melanin Binding, Cellular Kinetics, and Single Photon Emission Computed Tomography/Comput…
2016
Melanin binding is known to affect the distribution and elimination of ocular drugs. The purpose of this study was to evaluate if the extent of drug uptake to primary retinal pigment epithelial (RPE) cells could be estimated based on in vitro binding studies with isolated melanin and evaluate the suitability of single photon emission computed tomography/computed tomography (SPECT/CT) in studying pigment binding in vivo with pigmented and albino rats. Binding of five compounds, basic molecules timolol, chloroquine, and nadolol and acidic molecules methotrexate and 5(6)-carboxy-2',7'-dichlorofluorescein (CDCF), was studied using isolated melanin from porcine choroid-RPE at pH 5.0 and 7.4. The…
Population pharmacokinetic meta-analysis of individual data to design the first randomized efficacy trial of vancomycin in neonates and young infants.
2019
Abstract Objectives In the absence of consensus, the present meta-analysis was performed to determine an optimal dosing regimen of vancomycin for neonates. Methods A ‘meta-model’ with 4894 concentrations from 1631 neonates was built using NONMEM, and Monte Carlo simulations were performed to design an optimal intermittent infusion, aiming to reach a target AUC0–24 of 400 mg·h/L at steady-state in at least 80% of neonates. Results A two-compartment model best fitted the data. Current weight, postmenstrual age (PMA) and serum creatinine were the significant covariates for CL. After model validation, simulations showed that a loading dose (25 mg/kg) and a maintenance dose (15 mg/kg q12h if <…
Comparison Study of Two Differently Clicked 18F-Folates—Lipophilicity Plays a Key Role
2018
Within the last decade, several folate-based radiopharmaceuticals for Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) have been evaluated; however, there is still a lack of suitable 18F-folates for clinical PET imaging. Herein, we report the synthesis and evaluation of two novel 18F-folates employing strain-promoted and copper-catalyzed click chemistry. Furthermore, the influence of both click-methods on lipophilicity and pharmacokinetics of the 18F-folates was investigated. 18F-Ala-folate and 18F-DBCO-folate were both stable in human serum albumin. In vitro studies proved their high affinity to the folate receptor (FR). The lipophilic character of …
Physical mechanisms of micro- and nanodomain formation in multicomponent lipid membranes.
2016
This article summarizes a variety of physical mechanisms proposed in the literature, which can generate micro- and nanodomains in multicomponent lipid bilayers and biomembranes. It mainly focusses on lipid-driven mechanisms that do not involve direct protein-protein interactions. Specifically, it considers (i) equilibrium mechanisms based on lipid-lipid phase separation such as critical cluster formation close to critical points, and multiple domain formation in curved geometries, (ii) equilibrium mechanisms that stabilize two-dimensional microemulsions, such as the effect of linactants and the effect of curvature-composition coupling in bilayers and monolayers, and (iii) non-equilibrium me…