HOCl-modified phosphatidylcholines induce apoptosis and redox imbalance in HUVEC-ST cells

Electrophilic attack of hypochlorous acid on unsaturated bonds of fatty acyl chains is known to result mostly in chlorinated products that show cytotoxicity to some cell lines and were found in biological systems exposed to HOCl. This study aimed to investigate more deeply the products and the mechanism underlying cytotoxicity of phospholipid-HOCl oxidation products, synthesized by the reaction of HOCl with 1-stearoyl-2-oleoyl-, 1-stearoyl-2-linoleoyl-, and 1-stearoyl-2-arachidonyl-phosphatidylcholine. Phospholipid chlorohydrins were found to be the most abundant among obtained products. HOCl-modified lipids were cytotoxic towards HUVEC-ST (endothelial cells), leading to a decrease of mitochondrial potential and an increase in the number of apoptotic cells. These effects were accompanied by an increase of the level of active caspase-3 and caspase-7, while the caspase-3/-7 inhibitor Ac-DEVD-CHO dramatically decreased the number of apoptotic cells. Phospholipid-HOCl oxidation products were shown to affect cell proliferation by a concentration-dependent cell cycle arrest in the G/G phase and activating redox sensitive p38 kinase. The redox imbalance observed in HUVEC-ST cells exposed to modified phosphatidylcholines was accompanied by an increase in ROS level, and a decrease in glutathione content and antioxidant capacity of cell extracts

Thermal Stability of the Human Immunodeficiency Virus Type 1 (HIV-1) Receptors, CD4 and CXCR4, Reconstituted in Proteoliposomes

BACKGROUND: The entry of human immunodeficiency virus (HIV-1) into host cells involves the interaction of the viral exterior envelope glycoprotein, gp120, and receptors on the target cell. The HIV-1 receptors are CD4 and one of two chemokine receptors, CCR5 or CXCR4. METHODOLOGY/PRINCIPAL FINDINGS: We created proteoliposomes that contain CD4, the primary HIV-1 receptor, and one of the coreceptors, CXCR4. Antibodies against CD4 and CXCR4 specifically bound the proteoliposomes. CXCL12, the natural ligand for CXCR4, and the small-molecule CXCR4 antagonist, AMD3100, bound the proteoliposomes with affinities close to those associated with the binding of these molecules to cells expressing CXCR4 and CD4. The HIV-1 gp120 exterior envelope glycoprotein bound tightly to proteoliposomes expressing only CD4 and, in the presence of soluble CD4, bound weakly to proteoliposomes expressing only CXCR4. The thermal stability of CD4 and CXCR4 inserted into liposomes was examined. Thermal denaturation of CXCR4 followed second-order kinetics, with an activation energy (E(a)) of 269 kJ/mol (64.3 kcal/mol) and an inactivation temperature (T(i)) of 56°C. Thermal inactivation of CD4 exhibited a reaction order of 1.3, an E(a) of 278 kJ/mol (66.5 kcal/mol), and a T(i) of 52.2°C. The second-order denaturation kinetics of CXCR4 is unusual among G protein-coupled receptors, and may result from dimeric interactions between CXCR4 molecules. CONCLUSIONS/SIGNIFICANCE: Our studies with proteoliposomes containing the native HIV-1 receptors allowed an examination of the binding of biologically important ligands and revealed the higher-order denaturation kinetics of these receptors. CD4/CXCR4-proteoliposomes may be useful for the study of virus-target cell interactions and for the identification of inhibitors

Étude de la (bio)dégradation des polymères par RMN.

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Étude de la (bio)dégradation des polymères par Résonance Magnétique Nucléaire.

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Le marquage isotopique pour évaluer de la biodégradation du Polyéthylène.

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Tracking the fate of carbon during microbial biodegradation of plastics.

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Solid-state NMR for the study of membrane systems: the use of anisotropic interactions

A review with 91 refs. The use of solid-state NMR as a tool to det. the structure of membrane mols. is reviewed with a particular emphasis on techniques that provide information on orientation or order. Expts. reported here have been performed in membranes, rather than in micelles or org. solvents. Several ways to prep. and handle the samples are discussed, like sample orientation and magic-angle spinning (MAS). Results concerning lipids, membrane peptides and proteins are included, as well as a discussion regarding the potential of such methods and their pitfalls. [on SciFinder (R)

Les outils moléculaires pour étudier la biodégradation des plastiques.

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Antimethanogenic activity of Monascus metabolites in the rumen revealed by the concentration of statins, their diversity and the presence of acid forms

International audienceMonascus-fermented cereals reduce methane production from the rumen. The identification of the metabolites responsible of the antimethanogenic effect is important to assess the potential of this strategy as a mitigation option in ruminant production. This study highlights metabolites from Monascus ruber associated to methane inhibition. An in vitro rumen screening test was used to rank solid-state fermented wheat samples for their ability to inhibit methane. Four active and four less -active samples were selected for metabolomics analysis using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) and the identity of discriminant variables responsible for this group distinction was assigned thanks to tandem mass spectrometry (MS/MS) experiments. A total of 28 discriminating metabolites were putatively identified based on their accurate m/z values, fragmentation pathways and information from databases. The chemical structure (identification level 1) was confirmed for 9 of them thanks to the available authentic chemical standards. Most of these metabolites belong to the chemical class of statins and their derivatives (n =13), four of them annotated as statin-like molecules were observed here for the first time. A targeted approach using LC-MS/MS was performed to measure the levels of known metabolites and showed that the lovastatin concentration in active samples was 16 -fold greater than in least -active samples. Whereas lovastatin was the major metabolite, up to 40 % of the total statins were represented by other statin molecules. Comparison of the functional capability of lovastatin lactone and lovastatin acid demonstrates that the acid form is responsible for the antimethanogenic activity in the rumen environment. This study shows that Monascus - fermented feeds contain a wide variety of statins in both lactone and acid forms. Information from this work provides insight for improving the antimethanogenic efficacy of diets containing bioactive Monascus metabolites in ruminant