Plasma hydroperoxide determination

The FOX assay applied to a skatole oxidation product isolated by HPLC gave a positive result, supporting the contention that it is skatolyl hydroperoxide (40) . Mixtures of 183 and the eight diastereoisomeric hydroperoxides 184 and 185 derived from thymidine (42), as shown in equation 64, can be separated and detected by RP-HPLC with UVD at 229 nm. Each isomer is determined by applying the FOX assay using a capillary reactor heated at 60 °C to provide sufficient time for total oxidation of the Fe(ll) ions, followed by UVD at 596 mn . A commercial kit based on the FOX assay for hydroperoxide determination in plasma, serum and tissue homogenizates appears in Table 2. 

Transport of dangerous goods (TDG), 745-6 Trauma, plasma oxidation level, 631 Triacetone triperoxide explosive, 707-8 Triacylglycerides, mass spectrometry, 689 Triarylgermyl hydroperoxide, formation, 822 Triarylphosphine, hydroperoxide determination, 679... 

A correlation may be established between the concentration of oxidized lipids and the TEARS value, expressed as MDA equivalents, in uM units. Correction is due in some cases for the interference by dyes or other factors. For example, the presence of anthocyanins in red cabbage leaves or turbiditjf causes overestimation of lipid hydroperoxides in plant tissue by the TEARS method. TEARS was used to assert the level of endogenous peroxides in hypo- and hyperthyroidism, both conditions being characterized by low lipid and lipoprotein plasma levels and enhanced oxidative metabolism . In a procedure for determination of TEARS in edible oils, the sample is placed in a centrifuge at 12000 g before measuring at 532 nm (e = 1.56 x 10 M cm ) . A usual procedure for determination of TEARS in certain complex matrices involves steam distillation of the aldehydes responsible for the value, instead of extraction. In nitrite-cured meats, excess nitrite may cause nitrosation of MDA, thus interfering with distillation. To avoid this interference sulfanilamide is added, which is converted to a diazonium salt and... 

A procedure for determination of lipid hydroperoxides in human plasma is based on kinetic measurement of the CL of luminol (124) with hemin (75a) catalysis . CLD of microperoxidase-catalyzed oxidation of luminol (124) or isoluminol (190) was applied to detection and determination of amino acid hydroperoxides after exposure to UV and y-irradiation A method for determination of hydroperoxides in the phospholipids of cultured cells uses isoluminol (190) and microperoxidase as catalyst " . Simultaneous determination of phosphatidylcholine hydroperoxides and cholesteryl ester hydroperoxides in human serum is carried out by quantitative extraction of the lipids, HPLC separation by column switching and CLD using isoluminol (190) with microperoxidase catalysis . ... 

Glycerol-3-phosphate oxidase (GPO), triglyceride determination, 633 GlycerophosphochoUne, unsaturated, 737 GlycerophosphoUpid hydroperoxides, human plasma, 690... 

Asai et al. (1999) determined that phospholipid hydroperoxides (PLOOH) are key products for oxidative injury in membranous phospholipid layers in the plasma, red blood cells (RBC), and liver of mice. The formation and accumulation of PLOOH have been confirmed in several cellular disorders, various diseases, and in aging. A lower PLOOH level was found in RBC of the spice-extract-fed mice (65 to 74% of the nonsupplemented control mice). The liver lipid peroxidizability induced with Fe2+/ascorbic acid was effectively suppressed in mice by dietary supplementation with the turmeric and capsicum extracts. Although no difference in the plasma lipids was observed, the liver triacylglycerol concentration of the turmeric-extract-fed mice was markedly reduced to half of the level in the control mice. These findings suggest that these spice extracts could act antioxidatively in vivo by food supplementation, and that the turmeric extract has the ability to prevent the deposition of triacylglycerols in the liver. 

Plasma vs. Corona Treatment of Polypropylene (PP1. Corona treatments of polyolefins to modify their surfaces are very common in the polymer industry. The chemistry at such surfaces has been widely studied by XPS (4). It is generally assumed that corona treatments create abundant amounts of radicals which react with oxygen to form a hydroperoxide. This reacts further to eventually form crosslinks, oxidized products (ranging from hydroxyls to esters) with and without chain scission. The latter process is believed to lead to low-molecular weight material. There is some controversy over this material. Its role in determining the surface properties of the modified polymer is not completely understood. Its formation cannot be demonstrated directly by XPS, but only by comparing spectra before and after washing. 

N4. Nourooz-Zadeh, J., Tajaddini-Sarmadi, J., Ling, K. L., and Wolff, S. P., Low-density lipoprotein is the major carrier of lipid hydroperoxides in plasma. Relevance to determination of total plasma lipid hydroperoxide concentrations. Biochem. J. 313, 781-786 (1996). 

The oxidation products of plasma and lipoprotein phospholipids have been the subject of extensive study by chromatographic and mass spectrometric methods. Earlier, workers had reported the simultaneous determination of phospholipid hydroperoxides and cholesteryl ester hydroperoxides in human plasma by HPLC with chemiluminescence monitoring. Lipid hydroperoxides were quantitatively extracted from human plasma with a mixture of -hexane and... 

The direct separation of phosphohpidhydroperoxides has now been achieved by further advances in HPLC and increased sensitivity by chemiluminescence detection. By reverse-phase HPLC, the hydroperoxides of phosphatidylcholine and phosphatidylethanolamine were separated and determined in stored spray-dried eggs (2.4. 4%), fresh ground meat (0.2%), and raw fish (0.4%). Silica HPLC with post-column chemiluminescence detection has been used to determine phospholipid hydroperoxides in human blood plasma and in the low-density lipoprotein fraction. 

Miyazawa, T., Eujimoto, K. and Oikawa, S-1. Determination of lipid hydroperoxides in low-density lipoprotein from human plasma using high performance liquid chromatography with chemiluminescence detection. Biomedical Chromatography 4, 131-134 (1990). 

Hydrogel Coating ofPoly(ether sulfone). Due to the fact that PES has no functional groups which allow a wet chemical modification, plasma-induced hydroperoxide formation presents a suitable method to carry out the subsequent thermoinitiated graftpolymerization of HEMA (cf. Fig. 12). The iodometric determination of the hydroperoxide concentration at the surface shows that a saturation value is achieved after 4 min of argon plasma treatment and subsequent air exposure [113]. 

Cellular systems have evolved a powerful and complex antioxidant defence system to limit inappropriate exposure to these stressors. a-Tocopherol is quantitatively the most important chain-breaking antioxidant in plasma and biological membranes. The antioxidant activities of chain-breaking antioxidants are determined primarily by how rapidly they scavenge peroxyl radicals, thereby preventing the propagation of free radical reactions. When the chromanol phenolic group of a-tocopherol (TOH) encounters a ROO it forms hydroperoxide (ROOH), and in the process a tocopheroxyl radical (TO ) is formed ... 

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