PubMed · 12458540
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Xiaoyu Li, David G Lynn. 2002-12-02. Polymerization on solid supports.. https://doi.org/10.1002/1521-3773(20021202)41%3A23%3C4567%3A%3Aaid-anie4567%3E3.0.co%3B2-6
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
A sensitive, selective, specific and rapid liquid chromatographic-electrospray ionization tandem mass spectrometric assay was developed and validated for the simultaneous determination in skeletal muscle of the Michael adducts between 4-hydroxy-trans-2-nonenal (HNE), one of the most reactive lipid peroxidation-driven unsaturated aldehyde, and glutathione (GSH) and the endogenous histidine-containing dipeptides carnosine (CAR) and anserine (ANS), with the final aim to use conjugated adducts as specific and unequivocal markers of lipid peroxidation. Samples (skeletal muscle homogenates from male rats) were prepared by protein precipitation with 1 vol. of a HClO(4) solution (4.2%; w/v) containing H-Tyr-His-OH as internal standard. The supernatant, diluted (1:1, v/v) in mobile phase, was separated on a Phenomenex Sinergy polar-RP column with a mobile phase of water-acetonitrile-heptafluorobutyric acid (9:1:0.01, v/v/v) at a flow rate of 0.2 ml/min, with a run time of 12 min. Detection was on a triple quadrupole mass spectrometer equipped with an ESI interface operating in positive ionization mode. The acquisitions were in multiple reaction monitoring (MRM) mode using the following precursor-->product ion combinations: H-Tyr-His-OH (IS): m/z 319.2--> 156.5+301.6; GS-HNE: m/z 464.3--> 179.1+308.0; CAR-HNE: m/z 383.1--> 110.1+266.6; ANS-HNE: m/z 397.2--> 109.1+126.1. The method was validated over the concentration ranges 1.5-90 (GS-HNE) and 0.4-40 (CAR-HNE, ANS-HNE) nmoles/g wet tissue, and the LLOQ were 1.25 and 0.33 pmoles injected respectively. The intra- and inter-day precisions (CV%) were <7.38% (<or=10.90% at the LLOQs); intra- and inter-assay accuracy (RE%) was within +/-7.0% for all the concentrations (<or=18% at the LLOQs). The method was applied to quantitate peptide-HNE Michael adducts in rat skeletal muscles exposed to oxidative stress to endogenously generate HNE, and the results indicate that CAR-HNE can be considered as an early, specific and stable marker of lipid peroxidation in excitable tissues.
3-Hydroxypropionaldehyde (3-HPA) produced by Lactobacillus reuteri is a broad-spectrum antimicrobial substance of glycerol conversion. The aim of the present work was to optimize 3-HPA production by Lb. reuteri ATCC 53608 using a two-step process. The first step was the production of Lb. reuteri cells in optimal conditions. Cells were then harvested by centrifugation and suspended in glycerol solution, which the resting cells bioconverted to 3-HPA. The effect of biomass concentration, temperature, glycerol concentration, anaerobic/micro-aerophilic conditions, and incubation time was studied for high 3-HPA production. 3-HPA accumulation was limited by the death of cells in contact with high concentrations of 3-HPA. However, a very high 3-HPA concentration of 235+/-3 mM was obtained after 45 min of incubation at 30 degrees C in 400 mM glycerol for an initial free-cell concentration of 1.6+/-0.3x10(10) viable cells/ml. A high viability was maintained at low temperatures in the range 5-15 degrees C, but with a slightly lower yield of 3-HPA at 5 degrees C compared with higher temperatures, up to 37 degrees C. Successive 1-h incubations of Lb. reuteri cells in 200 mM glycerol at 15 degrees C to tentatively reuse the cells resulted in decreasing 3-HPA concentrations at the end of each cycle, with two successful production cycles yielding high 3-HPA concentrations of 147+/-1 mM and 128+/-2 mM.
Cardiovascular disease (CVD) is the leading cause of death in most industrialized countries. Cranberries were evaluated for their potential roles in dietary prevention of CVD. Cranberry extracts were found to have potent antioxidant capacity preventing in vitro LDL oxidation with increasing delay and suppression of LDL oxidation in a dose-dependent manner. The antioxidant activity of 100 g cranberries against LDL oxidation was equivalent to 1000 mg vitamin C or 3700 mg vitamin E. Cranberry extracts also significantly induced expression of hepatic LDL receptors and increased intracellular uptake of cholesterol in HepG2 cells in vitro in a dose-dependent manner. This suggests that cranberries could enhance clearance of excessive plasma cholesterol in circulation. We propose that additive or synergistic effects of phytochemicals in cranberries are responsible for the inhibition of LDL oxidation, the induced expression of LDL receptors, and the increased uptake of cholesterol in hepatocytes.