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PubMed2001

Free radical oxidative damage and Alzheimer's disease.

There is increasing evidence that free radical-induced oxidative damage may play a role in the pathogenesis of Alzheimer's disease. Free radicals are reactive oxygen compounds that may attack and damage lipids, proteins, and DNA. The brain is especially sensitive to oxidative damage because of its high content of readily oxidized fatty acids, high use of oxygen, and low levels of antioxidants. Evidence for oxidative damage has been obtained from postmortem brain tissue as well as from living patients with Alzheimer's disease. Antioxidants such as vitamin E show promise that they may help in treating the disease.

Aged↗
PubMed1998

Enzymatic repair of oxidative damage to human apolipoprotein A-I.

Oxidative damage to apolipoprotein A-I that occurs in vivo commonly involves methionine oxidation, and is accompanied by alterations in structure, lipid association, and cholesterol efflux function. We have used the enzyme peptide methionine sulfoxide reductase (PMSR) to reverse this damage, and shown by a variety of criteria that enzyme treatment restores the primary, secondary, and tertiary structure and lipid association characteristic of the native unoxidized protein. Lipid-associated as well as lipid-free apolipoprotein A-I reacts with PMSR, suggesting that enzymatic reduction of oxidized apolipoprotein A-I in high density lipoproteins can result in restoration of biological activity and the ability to promote cholesterol efflux from cells.

Animals↗
PubMed2001

Age-related changes in oxidative damage to lipids and DNA in rat skin.

Skin is a tissue exposed most frequently to oxidative stress from the environment in daily life. Age-related changes of oxidative damage and antioxidant enzyme activity in the skin were examined in male Fischer 344 rats aged 6 to 30 months. The contents of phosphatidylcholine hydroperoxide (PCOOH) and thiobarbituric acid-reacting substances (TBARS) increased linearly with age. The content of cholesterol hydroperoxide increased until 24 months of age and then decreased. The content of 8-oxo-2'-deoxyguanosine (8-oxodG) increased gradually with age, and was significantly higher at 30 months of age than at 6 months of age. Superoxide dismutase activity tended to decrease with age. The activities of catalase and glutathione peroxidase showed no changes with age. We examined the effect of dietary restriction on the accumulation of oxidative damage in rat skin. The increase in PCOOH content in the skin of dietary-restricted rats was suppressed until 30 months of age. The TBARS and cholesterol hydroperoxide contents in the skin of dietary-restricted rats were significantly lower than in the skin of ad libitum-fed rats, while the 8-oxodG content was somewhat lower in the dietary-restricted rats than the ad libitum-fed rats. These results indicate that oxidative damage to the lipids and DNA in rat skin increases with age and that dietary restriction delays the accumulation of oxidative damage in skin.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

Different onsets of oxidative damage to DNA and lipids in bone marrow and liver in rats given total body irradiation.

We examined time-dependent changes in antioxidant vitamins and oxidative damage to DNA and lipids in the bone marrow, liver, and plasma of rats given total body irradiation (TBI) with X-rays at 3 Gy. The oxidative damage to DNA and lipids was evaluated by measuring increases of 8-hydroxydeoxyguanosine (8OHdG) in DNA and 4-hydroxy-2-nonenal (HNE), respectively. After the TBI, marked increases in 8OHdG and HNE were detected at 3 to 5 h in the bone marrow, while gradual increases in these parameters were detected after a few days in the liver. These changes in 8OHdG and HNE were well correlated within each tissue. In the bone marrow, levels of both vitamin C and vitamin E were decreased by the TBI; however, the changes in vitamin C were earlier and greater than those in vitamin E. In the liver, the level of vitamin C did not decrease, but that of vitamin E decreased due to the TBI. Changes in HNE, vitamin C, and vitamin E in the plasma were similar to those in the liver. Within each tissue, the time of decrease in antioxidants was almost the same as that of the increase in oxidative damage. An increase in total iron due to the TBI was also detected in these tissues. In particular, the total iron in the bone marrow was markedly increased at a few hours after the TBI, with a slight increase in transferrin and no increase in ferritin. Exposure studies performed on cells or isolated DNA showed that an increase in 8OHdG was detected immediately after irradiation at more than 100 Gy in bone marrow cells and at less than 10 Gy in isolated DNA, suggesting that an increase in 8OHdG is undetectable even in bone marrow immediately after the TBI at 3 Gy. These results indicate that the onset of oxidative damage to DNA and lipids was delayed after TBI at 3 Gy, that it was quite different in the bone marrow and the liver, and that an increase in iron and decrease in antioxidant vitamins were involved in the mechanism of oxidative damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Oxidative damage during aging targets mitochondrial aconitase.

The mechanisms that cause aging are not well understood. The oxidative stress hypothesis proposes that the changes associated with aging are a consequence of random oxidative damage to biomolecules. We hypothesized that oxidation of specific proteins is critical in controlling the rate of the aging process. Utilizing an immunochemical probe for oxidatively modified proteins, we show that mitochondrial aconitase, an enzyme in the citric acid cycle, is a specific target during aging of the housefly. The oxidative damage detected immunochemically was paralleled by a loss of catalytic activity of aconitase, an enzyme activity that is critical in energy metabolism. Experimental manipulations which decrease aconitase activity should therefore cause a decrease in life-span. This expected decrease was observed when flies were exposed to hyperoxia, which oxidizes aconitase, and when they were given fluoroacetate, an inhibitor of aconitase. The identification of a specific target of oxidative damage during aging allows for the assessment of the physiological age of a specific individual and provides a method for the evaluation of treatments designed to affect the aging process.

Aconitate Hydratase↗
PubMed2002

Oxidative damage increases with age in a canine model of human brain aging.

We assayed levels of lipid peroxidation, protein carbonyl formation, glutamine synthetase (GS) activity and both oxidized and reduced glutathione to study the link between oxidative damage, aging and beta-amyloid (Abeta) in the canine brain. The aged canine brain, a model of human brain aging, naturally develops extensive diffuse deposits of human-type Abeta. Abeta was measured in immunostained prefrontal cortex from 19 beagle dogs (4-15 years). Increased malondialdehyde (MDA), which indicates increased lipid peroxidation, was observed in the prefrontal cortex and serum but not in cerebrospinal fluid (CSF). Oxidative damage to proteins (carbonyl formation) also increased in brain. An age-dependent decline in GS activity, an enzyme vulnerable to oxidative damage, and in the level of glutathione (GSH) was observed in the prefrontal cortex. MDA level in serum correlated with MDA accumulation in the prefrontal cortex. Although 11/19 animals exhibited Abeta, the extent of deposition did not correlate with any of the oxidative damage measures, suggesting that each form of neuropathology accumulates in parallel with age. This evidence of widespread oxidative damage and Abeta deposition is further justification for using the canine model for studying human brain aging and neurodegenerative diseases.

Aging↗
PubMed2002

Human mitochondrial transcription factor A binds preferentially to oxidatively damaged DNA.

Mitochondrial transcription factor A (mtTFA) is necessary for both transcription and maintenance of mtDNA, and is also one of the high mobility group (HMG) proteins that preferentially binds to cisplatin-damaged DNA. In this study we confirmed the preferential binding of mtTFA to cisplatin-damaged DNA, and also discovered that mtTFA binds to oxidatively damaged DNA. The affinity for oxidatively damaged DNA of mtTFA is higher for A/8-oxo-dG and C/8-oxo-dG than for G/8-oxo-dG and T/8-oxo-dG. Our findings suggest that mtTFA plays an important role in the recognition of oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

Helicobacter pylori infection is associated with oxidatively damaged DNA in human leukocytes and decreased level of urinary 8-oxo-7,8-dihydroguanine.

Helicobacter pylori infection is responsible for inflammation, increased production of reactive oxygen species and oxidatively damaged DNA in the gastric mucosa. There is also evidence which suggests that H.pylori infection may lead to the development of several extragastroduodenal pathologies with reactive oxygen species involvement. In order to assess whether the infection may impose oxidatively damaged DNA not only in the target organ (stomach) but in other organs as well we decided, for the first time, to analyse the two kinds of oxidatively damaged DNA biomarkers: urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanine (8-oxoGua) as well as the level of oxidatively damaged DNA in leukocytes. Using high performance liquid chromatography prepurification/gas chromatography with isotope dilution mass detection methodology, we examined the amount of oxidatively damaged DNA products excreted into urine and the amount of 8-oxodG in the DNA of leukocytes' (with the the HPLC/EC technique) in three groups of children: (i) control group, (ii) H.pylori infected children and (iii) children with gastritis where H.pylori infection was excluded. The levels of 8-oxodG in DNA isolated from leukocytes of H.pylori infected patients and in the group with gastritis without H.pylori infection were significantly higher than in DNA isolated from the control group. The mean level of 8-oxoGua in urine samples of children infected with H.pylori was significantly lower than in the urine of the group with gastritis without H.pylori infection. The data suggest that inflammation itself, not just H.pylori infection, is responsible for the observed rise of 8-oxodG level in leukocytes. However, the observed decrease in the level of modified base in urine seems to be specific for H.pylori infection and possibly linked with nitric oxide mediated inhibition of a key base excision repair enzyme (human 8-oxo-7, 8-dihydroguanine glycosylase) responsible for the repair of 8-oxo-7,8-dihydroguanine.

Adolescent↗
PubMed2000

Caloric restriction of rhesus monkeys lowers oxidative damage in skeletal muscle.

In laboratory rodents, caloric restriction (CR) retards several age-dependent physiological and biochemical changes in skeletal muscle, including increased steady-state levels of oxidative damage to lipids, DNA, and proteins. We used immunogold electron microscopic (EM) techniques with antibodies raised against 4-hydroxy-2-nonenal (HNE) -modified proteins, dinitrophenol, and nitrotyrosine to quantify and localize the age-dependent accrual of oxidative damage in rhesus monkey vastus lateralis skeletal muscle. Using immunogold EM analysis of muscle from rhesus monkeys ranging in age from 2 to 34 years old, a fourfold maximal increase in levels of HNE-modified proteins was observed. Likewise, carbonyl levels increased approximately twofold with aging. Comparing 17- to 23-year-old normally fed to age-matched monkeys subjected to CR for 10 years, levels of HNE-modified proteins, carbonyls, and nitrotyrosine in skeletal muscle from the CR group were significantly less than control group values. Oxidative damage largely localized to myofibrils, with lesser labeling in other subcellular compartments. Accumulation of lipid peroxidation-derived aldehydes, such as malondialdehyde and 4-hydroxy-2-alkenals, and protein carbonyls were measured biochemically and confirmed the morphological data. Our study is the first to quantify morphologically and localize the age-dependent accrual of oxidative damage in mammalian skeletal muscle and to demonstrate that oxidative damage in primates is lowered by CR.

Animals↗
PubMed2001

Recent advances in the design of iron chelators against oxidative damage.

Iron imbalance plays a pivotal role in oxidative damages associated with a wide range of pathological conditions. However, owing to the essential role of iron in biological processes, the beneficial effects of iron chelation therapy against oxidative damage have to be balanced against potential toxicity. The present review briefly introduces iron redox biochemistry and oxidative-stress associated pathologies, surveys recent advances in iron chelating strategies and summarizes some of our recent findings in this field, with a special emphasis on the chemical design constraints one must satisfy in order to synthesize iron chelators which could be beneficial against oxidative stress without inducing iron depletion of the body. The concept of oxidative stress activatable iron chelators is presented as a new paradigm for safe and efficient treatment of oxidative-stress associated conditions.

Animals↗
PubMed2003

Hpr6.6 protein mediates cell death from oxidative damage in MCF-7 human breast cancer cells.

Reactive oxygen species (ROS) cause cell death and are associated with a variety of maladies, from trauma and infection to organ degeneration and cancer. Cells mount a complex response to oxidative damage that includes signaling from transmembrane receptors and intracellular kinases. We have analyzed the response to oxidative damage in human breast cancer cells expressing the Hpr6.6 (human membrane progesterone receptor) protein. Although Hpr6.6 is related to a putative progesterone-binding protein, Hpr6.6 is widely expressed in epithelial tissues and shares close homology with a budding yeast damage response protein called Dap1p (damage response protein related to membrane progesterone receptor). We report here that the Hpr6.6 protein regulates the response to oxidative damage in breast cancer cells. Expression of Hpr6.6 in MCF-7 cells sensitized the cells to death following long-term/low dose or short-term/high dose treatment with hydrogen peroxide. Cell death did not occur through a typical apoptotic mechanism and corresponded with hyperphosphorylation of the Akt and IkappaB proteins. However, inhibition of Akt activation and IkappaB degradation had no effect on Hpr6.6-mediated cell death, suggesting that Hpr6.6 regulates cell death through a novel oxidative damage response pathway. Our work indicates a key regulatory function for Hpr6.6 in epithelial tissues exposed to oxidative damage.

Amino Acid Sequence↗
PubMed2000

Antioxidant actions of du-zhong (Eucommia ulmoides Oliv.) toward oxidative damage in biomolecules.

This study aimed to investigate the antioxidant effect of water extracts of Du-zhong (WEDZ) on oxidative damage in biomolecules such as deoxyribose, DNA, and 2'-deoxyguanosine (2'-dG) as induced by Fenton reaction. The WEDZ used included leaves, raw cortex, and roasted cortex. All of the WEDZ inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H2O2/ascorbic acid in a concentration dependent manner. At a concentration of 1.14 mg/mL, the inhibitory effect of the extracts of leaves, roasted cortex, and raw cortex was 85.2%, 68.0% and 49.3%, respectively. The extract of leaves inhibited the strand-breaking of DNA induced by the Fenton reaction at concentrations of 5 and 10 micrograms/microL. This inhibitory effect was similar to mannitol whereas the extracts of raw cortex and roasted cortex had no inhibitory effect at all. WEDZ also inhibited the oxidation of 2'-dG to 8-OH-2'-dG induced by Fe(3+)-EDTA/H2O2/ascorbic acid. Gallic acid had a prooxidant effect, but trolox and mannitol had an antioxidant effect. The leaf extract had a marked inhibitory effect on Fenton reaction induced oxidative damage in biomolecules. The extract of roasted cortex exhibited modest inhibition while the extract of raw cortex had the least inhibitory effect on oxidative damage in biomolecules. This is in contrast to gallic acid in the same reaction system, whose higher reducing power and weaker chelating ability may contribute to its prooxidant effect. In the present study, leaf extract of Du-zhong had inhibitory effect on oxidative damage in biomolecules. Therefore, drinking of Du-zhong tea (leaf extract) over a long period of time may have anticancer potential.

Antibiotics, Antineoplastic↗
PubMed2002

Prevention of mitochondrial oxidative damage using targeted antioxidants.

Mitochondrial-targeted antioxidants that selectively block mitochondrial oxidative damage and prevent some types of cell death have been developed. These antioxidants are ubiquinone and tocopherol derivatives and are targeted to mitochondria by covalent attachment to a lipophilic triphenylphosphonium cation. Because of the large mitochondrial membrane potential, these cations accumulated within mitochondria inside cells, where the antioxidant moiety prevents lipid peroxidation and protects mitochondria from oxidative damage. The mitochondrially localized ubiquinone also protected mammalian cells from hydrogen peroxide-induced apoptosis while an untargeted ubiquinone analogue was ineffective against apoptosis. When fed to mice these compounds accumulated within the brain, heart, and liver; therefore, using these mitochondrial-targeted antioxidants may help investigations of the role of mitochondrial oxidative damage in animal models of aging.

Animals↗
PubMed2006

Voltammetric behaviour of DNA bases at a screen-printed carbon electrode and its application to a simple and rapid voltammetric method for the determination of oxidative damage in double stranded DNA.

Screen-printed carbon electrodes (SPCEs) have been investigated as possible sensors to identify gamma-irradiation induced oxidative damage in double stranded (ds) DNA. Studies were undertaken to explore the possibility of using both cyclic voltammetry and differential pulse voltammetry to identify changes due to oxidative damage. Initially, guanine, adenine and 8-oxoguanosine were examined and it was found possible to differentiate them from their voltammetric responses. The voltammetric response of 8-oxoguanosine was found to be linear over the concentration range 1-400 microM, with a slope of 0.0296 microA microM(-1) (R2 value of 0.9984), in the presence of 2mM concentrations of guanine and adenine. Investigations were made into harnessing these findings to identify oxidative damage in gamma-irradiated dsDNA. The presence of oxidative damage in these samples was readily identifiable, and the magnitude of the voltammetric response was found to be dose dependant (R2=0.9919). A simple sample preparation step involving only the dissolution of double stranded DNA sample in the optimised electrolyte (0.1M acetate buffer pH 4.5) was required. This report appears to be first describing the use of a SPCE to detect DNA damage which can be related to the dose of gamma-radiation used.

Carbon↗
PubMed1997

Decrease in accessible thiols as an index of oxidative damage to membrane proteins.

The effect of several oxidative agents (hydrogen peroxide, tert-butyl hydroperoxide, menadione, AAPH, peroxynitrite and ionizing radiation) on the ratio of weakly to strongly immobilized residues of erythrocyte membrane-bound maleimide-tempo spin label (h(w)/h(s) ratio) was studied in order to test the hypothesis that a decrease in the h(w)/h(s) ratio may be a general index of oxidative damage to membrane proteins. Most of the agents studied decreased though H2O2 almost did not affect and ionizing radiation increased the h(w)/h(s) ratio. In parallel, the ratio of DTNB accessible/DTNB inaccessible membrane protein-SH groups was determined from membrane-SH group measurements with the Ellman reagent in the absence and in the presence of sodium dodecyl sulfate. This ratio decreased in all cases studied and seems to be a more universal and easy to measure parameter to describe the oxidative damage to membrane proteins.

Adult↗
PubMed2005

Effects of vitamin E on phospholipase A2 activity and oxidative damage to the liver in streptozotocin-induced diabetic rats.

BACKGROUND: The purpose of the present study was to investigate the effects of vitamin E on oxidative stress and cell membrane fluidity in the liver of streptozotocin (STZ)-induced diabetic rats. METHODS: Sprague-Dawley male rats weighing 100 +/- 10 g were fed a vitamin E-free diet (the DM-0E group), a 40 mg vitamin E/kg diet (the DM-40E group), or a 400 mg vitamin E/kg diet (the DM-400E group). RESULT: Dietary vitamin E reduced the increased concentration of lipid peroxides in the liver tissues of diabetic rats through decreasing their increased phospholipase A(2) (PLA(2)) activity and phosphatidylethanolamine hydrolysis. However, vitamin E reduced the accumulation of superoxide radical and decreased the generation of oxidative damage substances, such as the carbonyl value, increased membrane fluidity and lowered oxidative damage. CONCLUSIONS: Vitamin E was found to be excellent for regulating the activity of PLA(2), reducing the generation of reactive oxygen species and damaging oxidative substances, and maintaining cell membrane fluidity in the liver of diabetic rats.

Animals↗
PubMed2004

Oxidative damage to nuclear DNA in hyperthyroid rat liver: inability of vitamin C to prevent the damage.

The effects of hyperthyroidism on oxidative DNA damage in liver tissue and modification by vitamin C supplementation were investigated in rats. Animals were rendered hyperthyroid by administration of L-thyroxine (0.4 mg/100 g food) for 25 d. In the plasma samples, T(3), T(4), and thyroid-stimulating hormone (TSH) were measured by radioimmunoassay and ascorbate spectrophotometrically. Oxidative damage to hepatic nuclear DNA was determined by measuring deoxy-guanosine (dG) and 8-oxodG by high-performance liquid chromatography with diode array detector electrochemical detection (HPLC-DAD-ECD). In hyperthyroidism, 8-oxodG/(10(5) dG) levels were significantly higher and plasma vitamin C levels lower than in control rats. The results of this experimental study show that oxidative damage to hepatic nuclear DNA increases in the hyperthyroid state and that vitamin C was not effective in preventing this damage.

Animals↗
PubMed2003

Influence of the origin and level of dietary protein on TBI-induced oxidative damage in mice.

The influence of the origin and level of dietary protein on oxidative damage of lipid, protein, and DNA in mice after total body irradiation (TBI) was examined. Male mice were fed two types of dietary protein (casein and soybean protein) and different dietary protein levels (casein, 8% and 20%; soybean protein, 8% and 20%), and then treated with TBI with X-rays. The levels of lipid peroxides and chromosomal damage did not differ among the groups that did not receive TBI. However, the oxidative damage of lipid increased due to TBI only in the 8% protein group. The chromosomal damage in bone marrow increased due to TBI regardless of the different protein diets, and the damage was higher in the 8% protein group than that in the 20% protein group. Protein carbonyl levels were consistently higher in the 8% protein group than in the 20% protein group. In the 8% protein group, a greater decrease in the relative spleen weight was also observed. Concentrations of antioxidants [vitamins C, E, and glutathione (GSH)] in the liver were lower, and the concentration of non-heme iron in the liver was higher in the 8% protein group than in the 20% protein groups. Mice fed a low-protein diet became susceptible to TBI-induced oxidative damage regardless of the origin of protein. Vitamin C and E values of the soybean protein group were markedly lower than those of the casein group.

Analysis of Variance↗