Subject oxidative stress

HININGER I A, MEYER-WENGER A, MOSER U, WRIGHT A, SOUTHON S, THURNHAN D, CHOPRA M, VAN CEN BERG H, OLMEDILLA B, FAVIER A E and ROUSSEL A M (2001) No significant effects of lutein, lycopene or beta-carotene supplementation on biological markers of oxidative stress and LDL oxidisability in healthy adult subjects. J Am Coll Nutr. 20(3) 232-238. 

Experimental evidence in humans is based upon intervention studies with diets enriched in carotenoids or carotenoid-contaiifing foods. Oxidative stress biomarkers are measured in plasma or urine. The inhibition of low density lipoprotein (LDL) oxidation has been posmlated as one mechanism by which antioxidants may prevent the development of atherosclerosis. Since carotenoids are transported mainly via LDL in blood, testing the susceptibility of carotenoid-loaded LDL to oxidation is a common method of evaluating the antioxidant activities of carotenoids in vivo. This type of smdy is more precisely of the ex vivo type because LDLs are extracted from plasma in order to be tested in vitro for oxidative sensitivity after the subjects are given a special diet. 

Collier et al. (1990) extended their studies relating to oxidative stress and diabetes by demonstrating that the levels of several free-radical scavengers (red cell superoxide dismutase, plasma thiols) were significantly reduced in 22 type 2 diabetic patients (mean age 53 years) in comparison with 15 control subjects (mean age 51 years). No significant diflFerences in red cell lysate thiols or... 

Subjecting cells to oxidative stress can result in severe metabolic dysfunctions, including peroxidation of membrane lipids, depletion of nicotinamide nucleotides, rises in intracellular free Ca ions, cytoskeletal disruption and DNA damage. The latter is often measured as formation of single-strand breaks, double-strand breaks or chromosomal aberrations. Indeed, DNA damage has been almost invariably observed in a wide range of mammalian cell types exposed to oxidative stress in a number... 

Table 13.2 Methods used to subject cells to oxidative stress that has produced increased intracellular DNA damage (see Halil well and Aruoma, 1991)...

Hepatic reperfusion injury is not a phenomenon connected solely to liver transplantation but also to situations of prolonged hypoperfusion of the host s own liver. Examples of this occurrence are hypovolemic shock and acute cardiovascular injur) (heart attack). As a result of such cessation and then reintroduction of blood flow, the liver is damaged such that centrilobular necrosis occurs and elevated levels of liver enzymes in the serum can be detected. Particularly because of the involvement of other organs, the interpretation of the role of free radicals in ischaemic hepatitis from this clinical data is very difficult. The involvement of free radicals in the overall phenomenon of hypovolemic shock has been discussed recently by Redl et al. (1993). More specifically. Poll (1993) has reported preliminary data on markers of free-radical production during ischaemic hepatitis. These markers mostly concerned indices of lipid peroxidation in the serum and also in the erythrocytes of affected subjects, and a correlation was seen with the extent of liver injury. The mechanisms of free-radical damage in this model will be difficult to determine in the clinical setting, but the similarity to the situation with transplanted liver surest that the above discussion of the role of XO activation, Kupffer cell activation and induction of an acute inflammatory response would be also relevant here. It will be important to establish whether oxidative stress is important in the pathogenesis of ischaemic hepatitis and in the problems of liver transplantation discussed above, since it would surest that antioxidant therapy could be of real benefit. 

Stadler, R. H., Fay, L. B., Antioxidative reactions of caffeine formation of 8-oxocaffeine (1,3,7-trimethyluric acid) in coffee subjected to oxidative stress, J. Agric. Food Chem., 43(5), 1332, 1995. (CA122 289398f)... 

It has been shown in many studies that protective effects of carotenoids can be observed only at small carotenoid concentrations, whereas at high concentrations carotenoids exert pro-oxidant effects via propagation of free radical damage (Chucair et al., 2007 Lowe et al., 1999 Palozza, 1998, 2001 Young and Lowe, 2001). For example, supplementation of rat retinal photoreceptors with small concentrations of lutein and zeaxanthin reduces apoptosis in photoreceptors, preserves mitochondrial potential, and prevents cytochrome c release from mitochondria subjected to oxidative stress induced by paraquat or hydrogen peroxide (Chucair et al., 2007). However, this protective effect has been observed only at low concentrations of xanthophylls, of 0.14 and 0.17 pM for lutein and zeaxanthin, respectively. Higher concentrations of carotenoids have led to deleterious effects (Chucair et al., 2007). 

It has been demonstrated in other cell types that lutein can inhibit expression of MMPs and/ or activity (Philips et al., 2007). For example, in dermal fibroblasts lutein inhibits expression of MMP-1 and decreases levels of MMP-2 protein (Philips et al., 2007). In melanoma cells, lutein inhibits MMP-1 expression while stimulating TIMP-2 (Philips et al., 2007). Moreover it has been shown that lutein inhibits elastin expression in fibroblasts subjected to oxidative stress by exposure to ultraviolet light (Philips et al., 2007). These results clearly indicate that lutein can play an important role in remodeling of the extracellular matrix. 

Ellis et al. [72] recently studied the effects of short- and long-term vitamin C therapy in the patients with chronic heart failure (CHF). It was found that oxygen radical production and TBAR product formation were higher in patients with CHF than in control subjects. Both short-term (intravenous) and long-term (oral) vitamin C therapy exhibited favorable effects on the parameters of oxidative stress in patients the treatments decreased oxygen radical formation and the level of lipid peroxidation and improved flow-mediated dilation in brachial artery. However, there was no correlation between changes in endothelial function and oxidative stress. 

Cystic fibrosis is the most common lethal autosomal-recessive disease, in which oxidative stress takes place at the airway surface [274]. This disease is characterized by chronic infection and inflammation. Enhanced free radical formation in cystic fibrosis has been shown as early as 1989 [275] and was confirmed in many following studies (see references in Ref. [274]). Contemporary studies also confirm the importance of oxidative stress in the development of cystic fibrosis. Ciabattoni et al. [276] demonstrated the enhanced in vivo lipid peroxidation and platelet activation in this disease. These authors found that urinary excretion of the products of nonenzymatic lipid peroxidation PGF2 and TXB2 was significantly higher in cystic fibrotic patients than in control subjects. It is of importance that vitamin E supplementation resulted in the reduction of the levels of these products of peroxidation. Exhaled ethane, a noninvasive marker of oxidative stress, has also been shown to increase in cystic fibrosis patients [277]. 

Figure 2. NO inhibits iron-induced lipid peroxidation. The rate of Oj consumption of HL-60 cells (5 X 10 /ml) was detennined using a YSI O2 monitor. Fe (20 pM) was added at the first arrow and subsequently NO (0.45 pM) was added (other arrows). When NO was added, the O2 consumption was inhibited for a period of a few min, then it resumed at near its initial rate until the reintroduction of additional NO. Also shown (lower dashed line) is a control of HL-60 cells subjected to Fe -induced oxidative stress in the absence of NO addition. The background rate of O2 uptake of the HL-60 cell suspension before the addition of Fe was 10 nM/sec. Upon the addition of 20 pM Fe, this rate increased to 220 nM/sec. The addition of NO resulted in a decrease in O2 consumption to <10 nM/sec. (From Kelley, E.E., Wagner, B.A., Buettner, G.R., and Bums, C.P., 1999, Arch. Biochem. Biophys. 370 97-104).

Cells may show a low level of autofluorescence at 413 nm when irradiated at 324 nm. This fluorescence dramatically increases when d -parinaric acid (159) is incorporated into the cell membrane, either by intercalation or esteriflcation. Exposure to oxidation stress of cells enriched with the 159 fluorescent probe causes diminution of the fluorescence intensity and is directly correlated with formation of lipid hydroperoxides. Addition of antioxidants, such as Vitamin E (21), abates fluorescence diminution. A blanc run of cells enriched with 159 but not subjected to oxidation stress is necessary to follow the degradation of 159 when exposed to UV irradiation. This method was applied to track lipid oxidation during apoptosis and other phenomena, triggered by toxic compounds such as H2O2, f-BuOOH and cumyl hydroperoxide (27)"° 11,424... 

An alternative method to TBARS for determination of MDA is formation of the DNP derivative and quantitation by RP-HPLC with DA-UVD, recording in the 195 to 500 nm range. Other carbonyl compounds present in the sample also form the corresponding DNP compounds and are also determined. The method was applied to MDA determination in plasma of rats, after they were subjected to oxidative stress by intraparental injection of a dose of bacterial lipopolysaccharide" . 

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