Search results for " INDUCTION"

Synthesis and inhibitory activity of dimethylamino-chalcone derivatives on the induction of nitric oxide synthase.

2002

A series of nine dimethylamino-chalcone derivatives (1,3-diaryl-propenones) was synthesized and screened as potential inhibitors of NO and PGE(2) production in the RAW 264.7 macrophage cell line. 4-Dimethylamino-2',5'-dimethoxychalcone (6) was found to be the most potent and dual inhibitor (IC(50s) in the submicromolar range) of NO and PGE(2) production. 2',6'-Dimethoxylation appeared to be an effective requirement for selective and potent inhibition of nitric oxide synthase induction as it was confirmed by Western blot analysis. Chalcone (6) at 25 mg kg(-1) by oral route, inhibited significantly the formation of oedema in the carrageenan-induced model of inflammation in mice.

13C-Decoupled J-Coupling Spectroscopy Using Two-Dimensional Nuclear Magnetic Resonance at Zero-Field

2017

We present a two-dimensional method for obtaining 13C-decoupled, 1H-coupled nuclear magnetic resonance (NMR) spectra in zero magnetic field using coherent spin-decoupling. The result is a spectrum determined only by the proton–proton J-coupling network. Detection of NMR signals in zero magnetic field requires at least two different nuclear spin species, but the proton J-spectrum is independent of isotopomer, thus potentially simplifying spectra and thereby improving the analytical capabilities of zero-field NMR. The protocol does not rely on a difference in Larmor frequency between the coupled nuclei, allowing for the direct determination of J-coupling constants between chemically equivalen…

Dual effects of increased glycogen synthase kinase-3β activity on adult neurogenesis

2013

Adult neurogenesis, the generation of new neurons during the adulthood, is a process controlled by several kinases and phosphatases among which GSK3β exerts important functions. This protein is particularly abundant in the central nervous system, and its activity deregulation is believed to play a key role in chronic disorders such as Alzheimer's disease. Previously, we reported that in vivo overexpression of GSK3β (Tet/GSK3β mice) causes alterations in adult neurogenesis, leading to a depletion of the neurogenic niches. Here, we have further characterized those alterations, finding a delay in the switching-off of doublecortin marker as well as changes in the survival and death rates of imm…

Definition of response to antiviral therapy in chronic hepatitis C

2000

Recent Advances in Asymmetric [3,3]-SigmatropicRearrangements

2003

The synthesis of new complex structures is still a challenge in preparative organic chemistry. Focusing on the generation of defined stereogenic centers, the [3,3]-sigmatropic rearrangements are known as reliable reactions. Always, a highly ordered transition state must be passed through, which allows the shift of chiral information from the reactant into the nascent product. Generally, the complete [1,3]- and, frequently, the [1,4]-chirality transfer enables one to predict the configuration of the new centers. This review focuses on Claisen and Cope rearrangements, which adopt the chiral information via a so termed asymmetric induction. This means, that the directing chiral subunit is plac…

Microsomal activation of dibenzo[def,mno]chrysene (anthanthrene), a hexacyclic aromatic hydrocarbon without a bay-region, to mutagenic metabolites.

2002

Metabolically formed dihydrodiol epoxides in the bay-region of polycyclic aromatic hydrocarbons are thought to be responsible for the genotoxic properties of these environmental pollutants. The hexacyclic aromatic hydrocarbon dibenzo[def,mno]chrysene (anthanthrene), although lacking this structural feature, was found to exhibit considerable bacterial mutagenicity in histidine-dependent strains TA97, TA98, TA100, and TA104 of S. typhimurium in the range of 18-40 his(+)-revertant colonies/nmol after metabolic activation with the hepatic postmitochondrial fraction of Sprague-Dawley rats treated with Aroclor 1254. This mutagenic effect amounted to 44-84% of the values determined with benzo[a]py…

Interplay of Chiral Side Chains and Helical Main Chains in Polyisocyanates

1996

Here we describe the synthesis of seven new copolymer series prepared by copolymerization of hexyl isocyanate with seven new chiral azo chromophores with an isocyano functionality. The resulting copolyisocyanates (Nylon 1) possess a helical polymer conformation. In the cases in which the chiral group and polymer chain are linked to the same phenyl ring (copolymer series VI-IX) a transfer of chirality to the polymer chain is possible. I.e. one helical twist sense is preferred in this case. By variation of the chiral center, polymers with preferable right- or left-handed helical conformation are accessible. The photochemical isomerization of the azo chromophore (trans → cis) is possible in hi…

Strategies to In Vitro Assessment of Major Human CYP Enzyme Activities by Using Liquid Chromatography Tandem Mass Spectrometry

2008

At the early stage of drug discovery, thousands of new chemical entities (NCEs) may be screened before a single candidate can be identified for development. Determining the role of CYP enzymes in the metabolism of a compound and evaluating the effect of NCEs on human CYP activities are key issues in pharmaceutical development as they may explain inter-subject variability, drug-drug interactions, non-linear pharmacokinetics and toxic effects. Reliable methods for determining enzyme activities are needed to characterize an individual CYP enzyme and to obtain a tool for the evaluation of its role in drug metabolism in humans. Different liquid chromatography tandem mass spectrometry methodologi…

Recent Advances in Asymmetric [3,3]-Sigmatropic Rearrangements.

2003

The synthesis of new complex structures is still a challenge in preparative organic chemistry. Focusing on the generation of defined stereogenic centers, the [3,3]-sigmatropic rearrangements are known as reliable reactions. Always, a highly ordered transition state must be passed through, which allows the shift of chiral information from the reactant into the nascent product. Generally, the complete [1,3]- and, frequently, the [1,4]-chirality transfer enables one to predict the configuration of the new centers. This review focuses on Claisen and Cope rearrangements, which adopt the chiral information via a so termed asymmetric induction. This means, that the directing chiral subunit is plac…

Feedback linearization control of wind turbine equipped with doubly fed induction generator

2017

This paper focuses on several control techniques of a wind turbine of rated power of about 1 MW. In particular, a wind generator equipped with an asynchronous doubly-fed induction machine has been considered and its dynamic model in MATLAB/SIMULINK environment has been implemented. Starting from this model the feedback linearization control has been derived, and several simulations have been carried out, with the aim of compare its dynamic performances with the classical field oriented control, and with the V/f control. The results allow us to conclude that a DFIG controlled by a feedback linearization technique ensures better dynamic performance.