Search results for "acids"

Liver X Receptor Regulates Arachidonic Acid Distribution and Eicosanoid Release in Human Macrophages

2013

Objective— Liver X receptors (LXRs) are oxysterol-activated nuclear receptors that are highly expressed in macrophages and regulate lipid homeostasis and inflammation. Among putative LXR target genes, lysophosphatidylcholine acyltransferase 3 (LPCAT3) involved in the Lands cycle controls the fatty acid composition at the sn-2 position of glycerophospholipids and, therefore, the availability of fatty acids, such as arachidonic acid (AA), used for eicosanoid synthesis. The aim of our study was to determine whether LXRs could regulate the Lands cycle in human macrophages, to assess the consequences in terms of lipid composition and inflammatory response, and to work out the relative contribut…

Lipoprotein-induced phenoloxidase-activity in tarantula hemocyanin.

2015

Phenoloxidases play vital roles in invertebrate innate immune reactions, wound closure and sclerotization processes in arthropods. In chelicerates, where phenoloxidases are lacking, phenoloxidase-activity can be induced in the oxygen carrier hemocyanin in vitro by proteolytic cleavage, incubation with the artificial inducer SDS, or lipids. The role of protein-protein interaction has up to now received little attention. This is remarkable, as lipoproteins - complexes of proteins and lipids - are present at high concentrations in arthropod hemolymph. We characterized the three lipoproteins present in tarantula hemolymph, two high-density lipoproteins and one very high-density lipoprotein, and…

Physico-chimie des lipopolysaccharides et réponse inflammatoire : rôle des lipoprotéines

2014

LPS is a potent bacterial pro-inflammatory agent, consisting of hydrophilic, polysaccharide part and of a lipid A which is considered like active moiety. Nevertheless, the O chain of LPS influences their aggregation in aqueous media. Therefore, our goal has been to determine the role of O chain on the LPS biological and physiopathological effects. Our work was organized according to three main axes, and led to the following findings :- development of a new LPS assay by LC-MS/MS. The combination of this new technique with LAL test allowed us to calculate an inactivation ratio which reflects the ability of host organism to inactivate LPS, especially through their transfer to HDL by PLTP. The …

Studien zum Vorgang der Wasserstoffübertragung, 67. Endioldiester durch acylierende elektroreduktive Dimerisierung von Carbonsäurechloriden mit Lithi…

1983

Aromatische, aliphatische und aromatisch-aliphatische Carbonsaurechloride (und Anhydride) werden mit Lithiumamalgam (Li/Hg) durch acylierende reduktive Dimerisierung in wechselnden Ausbeuten (meist 70%) in cis- und/oder trans-Endioldiester 1–10 ubergefuhrt. Der Einflus des Losungsmittels auf den Reaktionsverlauf wird untersucht. Aus 2,2′-Diphensauredichlorid entsteht das Phenanthrenderivat 7, aus Phthaloyldichlorid Phthalid 8. Li/Hg wandelt Diphenyl-phosphinylchlorid in Tetraphenyldiphosphandioxid (15) um. Auf die Bestimmung der Halbstufenpotentiale von 12 Saurechloriden und vier 1,2-Diketonen grundet sich die Formulierung des Reaktionsmechanismus. 1,2-Diketone sind Zwischenprodukte der acy…

Cavitands incorporating a Lewis acid dinickel chelate function as receptors for halide anions.

2015

The halide binding properties of the cavitand [Ni2(L(Me2H4))](2+) (4) are reported. Cavitand 4 exhibits a chelating N3Ni(μ-S)2NiN3 moiety with two square-pyramidal Ni(II)N3S2 units situated in an anion binding pocket of ∼4 Å diameter formed by the organic backbone of the (L(Me2H4))(2-) macrocycle. The receptor reacts with fluoride, chloride (in MeCN/MeOH), and bromide (in MeCN) ions to afford an isostructural series of halogenido-bridged complexes [Ni2(L(Me2H4))(μ-Hal)](+) (Hal = F(-) (5), Cl(-) (6), and Br(-) (7)) featuring a N3Ni(μ-S)2(μ-Hal)NiN3 core structure. No reaction occurs with iodide or other polyatomic anions (ClO4(-), NO3(-), HCO3(-), H2PO4(-), HSO4(-), SO4(2-)). The binding ev…

Photochemical Synthesis and Reactivity of New Chloro-Bridged Complexes with Tungstenocene (η5-C5H5)(η5-C5H4PPh2)WClX (X = H, Cl) and Tetracarbonylmet…

1999

Chloro-bridged bimetallic complexes (η5-C5H5)[η5-C5H4PPh2M′(CO)4]W(μ-Cl)X [X = Cl (3), × = H (4); M′ = Cr, W] were prepared by photochemical irradiation of (η5-C5H5)[η5-C5H4PPh2M′(CO)5]WClX [X = Cl (1), × = H (2); M′ = Cr, W]. The reactivity of the chloro-bridged complexes towards Lewis bases was studied; by exposure to CO or phosphanes, a facile cleavage of the chloro bridge accompanied by regio- and stereospecific coordination at M′ occurs. The X-ray structure of complex 3 (M′ = W) is reported.

Activation of C−H Bonds in Five-Membered Heterocycles by a Half-Sandwich Yttrium Alkyl Complex

2001

Bonding Trends in Lewis Acid Adducts of S 4 N 4 – X‐ray Structure of TeCl 4 ·S 4 N 4

2006

Tetrasulfur tetranitride and tellurium tetrachloride react in dichloromethane to form a 1:1 adduct TeCl4·S4N4 (1). The crystal structure of 1 shows that TeCl4 is bonded to the S4N4 ring through a Te–N linkage. As a consequence, the transannular S···S bonds in S4N4 are broken and the molecule assumes an open, monocyclic conformation. The Te–N bond of 2.16(1) A is slightly longer than the single bond. The S–N bonds span a range of 1.55(1)–1.67(1) A. The adduct 1 was also characterized by mass spectrometry and Raman spectroscopy. The bonding and spectroscopic properties of 1 are compared by DFT calculations at the B3PW91/(RLC ECP) level of theory with those of BF3·S4N4 (2), SO3·S4N4 (3), AsF5·…

Aqueous solution chemistry of alkyltin(IV) compounds for speciation studies in biological fluids and natural waters

2012

Abstract Organotin(IV) cations behave as Lewis acids of different strength depending on the charge, according to the following acidity scale: RSn3+ > R2Sn2+ > R3Sn+. For this reason they can react with Lewis bases containing –O, –N, –S donor groups to form complex species of different stability. Complex formation of organotin(IV) moieties with a great number of inorganic and organic ligands in aqueous solution is reviewed here in the light of their environmental and biological impact. To this end, complex species formation was considered in different ionic media and at different ionic strengths, with reference to the composition of natural waters and biological fluids. In particular, the in…

Functionality of endothelial cells on silk fibroin nets: Comparative study of micro- and nanometric fibre size

2007

Biomimetic material design, such as mimicking nanostructured components of the extracellular matrix, is an actual challenge for biomaterial research with a high impact on tissue engineering and regenerative medicine. Thus, understanding the cellular response at the cell biological and molecular level and the consequences of various chemically or physically modified biomaterials is highly important. In the present study we assessed the response of human umbilical vein endothelial cells (HUVEC) and outgrowth endothelial cells (OEC) from endothelial progenitor cells to different variants of nanofibrous silk fibroin nets in comparison to microfibrous silk fibroin scaffolds with regard to cellul…