Plasma measuring oxidation products

Detailed Procedures for Some Methods that Measure Oxidation Products in Plasma... 

For these reasons, and because they can be measured in urine and plasma, PGF are generally considered to offer a noninvasive, sensitive, specific direct method for measuring lipid peroxidation in vivo (Y1). The main drawback is that the methods are very complicated, tedious, and not usually available in clinical laboratories. Like other lipid oxidation products, PGF can be generated ex vivo. For this reason, fluids should be preserved with butylated hydroxy toluene (BHT) and EDTA to prevent further oxidation and measured immediately or stored at —70°C (M8). An ELISA has been developed for urine for 8-Iso-PGF2a that is commercially available (02), but the method is tedious since it requires a column separation prior to ELISA (Bl). Also, since PGF are mainly indicators of arachidonic acid oxidation, they do not reflect oxidation of the major PUFA comprising lipoproteins. 

HODEs are primarily Cl8 oxidation products of linoleic acid (J9). These have not been as widely studied as isoprostanes, but like isoprostanes, these are specific products of nonenzymatic lipid peroxidation that are associated with arteriosclerotic disease and are found in arteriosclerotic plaques (J9, W2). Likewise, they are measured by specific GC/MS techniques that are generally not available in clinical laboratories (JIO). They have the advantage that they are products of the major PUFA in lipoproteins—linoleic acid— but they have generally been measured only in lipoproteins extracted from plasma. 

HNE is a 4-hydroxy-2-alkenal (Fig. 5) that is a product of arachidonic and linoleic acid and better represents the mixture of fatty acids in lipoproteins than do some other oxidation products. HNE is cytotoxic to cells and causes the rapid depletion of glutathione, inhibition of DNA, RNA, and protein synthesis and, at high levels, inhibition of many metabolic processes leading to rapid cell death (E4). HNE is a specific product that has been measured by GC/MS and HPLC (E4). HPLC methods may be more accessible to clinical laboratories than GC/MS and have been used both for measuring levels of HNE and HNE protein adducts (U2), but generally they have been measured only in lipoprotein extracts or tissue and not in whole plasma or serum. 

Our study relied on regression analysis to examine the relative effects of two related dietary factors (TG and oxidized TG). Obviously, it would be better if we could have compared the effects of fresh and aged walnut oil on factor Vila. Furthermore, we need to identify the active component. However, it is of interest that plasma linoleic acid had been identified as the factor that activated factor VII in Swedish men (52). In that study, oxidation products of linoleic acid were not measured. Could it be that linoleic acid reflected the absorption of linoleic acid oxidation products in the Swedish study Perhaps the oxidized linoleic acid and not the cfr.cw-linoleic acid itself was the activator of factor VII. 

Fatty acid oxidation disorders should be considered in any case of unexplained hypoglycemia and/or myopathy. The laboratory diagnosis relies on the measurement of plasma acylcarnitines and urine organic acids, mainly the alternative fatty acid oxidation products. Novel defects may be expected to be delineated, especially the short- and medium-chain enzymes have not... 

Potassium cyanide catalyzed oxidation of PLP with subsequent quantification of the highly fluorescent oxidation product, 4-pyridoxic acid-5 -phosphate, has been used to determine PLP levels in human plasma, brain tissue and cell cultures (74,126,127). The sensitivity of this method has been reported to be even better than methods based on PLP semicarbazone formation (127). PL is not determined by these methods this vitamer is oxidized to 4-pyridoxic acid lactone, which shows little fluorescence at pH 2.5 to 3.8 of the mobile phases used (Table 2). Hess and Vuilleumier (128) overcame this problem by alkaline delactonization of pyridoxic acid lactone to yield the highly fluorescent 4-PA. The determination of PL as 4-PA suffers from the disadvantage that each sample has to be analyzed twice. In the first analysis, cyanide oxidation is omitted and the basal 4-PA concentration is measured. In the second analysis, PL is converted to 4-PA as described. The concentration of PL is determined from the difference between the two assays for 4-PA. 

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

Two colorimetric methods are recommended for boron analysis. One is the curcumin method, where the sample is acidified and evaporated after addition of curcumin reagent. A red product called rosocyanine remains it is dissolved in 95 wt % ethanol and measured photometrically. Nitrate concentrations >20 mg/L interfere with this method. Another colorimetric method is based upon the reaction between boron and carminic acid in concentrated sulfuric acid to form a bluish-red or blue product. Boron concentrations can also be deterrnined by atomic absorption spectroscopy with a nitrous oxide—acetjiene flame or graphite furnace. Atomic emission with an argon plasma source can also be used for boron measurement. 

Peroxide Value, Fats and Oils (PV) (Cd 8-53) determines all substances, in terms of milliequivalents of peroxide per 1000 g of sample, that oxidize potassium iodide (KI). These substances generally are assumed to be peroxides or products of fat oxidation. Phosphorus in Oils (Ca 13-55) estimates the phospholipid content of crude, degummed, and refined vegetable oils in terms of phosphorus. Refineries often use induction coupled plasma (ICP) spectrographs to analyze divalent cations rapidly in aspirated crude oil. The calcium and magnesium measured are mainly responsible for nonhydratable phosphatides (NHP) and are determined directly. An AOCS method for analysis by ICP is being developed. 

Hydrous sodium titanate was prepared by the method of Dosch and Stephens (1). Titanium isopropoxide was slowly added to a 15 wt% solution of sodium hydroxide in methanol. The resulting solution was hydrolyzed by addition to 10 vol% water in acetone. The hydrolysis product is an amorphous hydrous oxide with a Na Ti ratio of 0.5 which contains, after vacuum drying at room temperature, approximately 13.5 wt% water and 2.5 wt% residual alcohol. The ion-exchange characteristics of the sodium titanate and the hydrolysis behavior of the nickel nitrate solutions were characterized using a combination of potentiometric titrations, inductively coupled plasma atomic emission (ICP) analysis of filtrates, and surface charge measurements obtained using a Matec electrosonic amplitude device. 

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