Types Of Oxidative Stress Research Articles

The delayed leaf senescence mutants of Arabidopsis, ore1, ore3, and ore9 are tolerant to oxidative stress.

Reactive oxygen species play a critical role in mediating the oxidative damage that causes senescence in a variety of aerobic organisms, from yeast to mammals. Genetic studies of these organisms have revealed that extended longevity is frequently associated with an increased resistance to stress. However, the relationship between life span and oxidative stress tolerance in plants is poorly understood. We have investigated the responses to oxidative stress in the delayed leaf senescence mutants of Arabidopsis thaliana, ore1, ore3, and ore9. The detached leaves of these mutants exhibit increased tolerance to various types of oxidative stress. The ore1, ore3, and ore9 mutants were also more tolerant to oxidative stress at the level of the whole plant, as determined by measuring physiological and molecular changes associated with oxidative stress. However, the activities of antioxidant enzymes were similar or lower in the mutants, as compared to wild type. These results suggest that the increased resistance to oxidative stress in the ore1, ore3, and ore9 mutants is not due to enhanced activities of these antioxidant enzymes. Taken together, our findings provide genetic evidence that oxidative stress tolerance is linked to control of leaf longevity in plants.

Source of tryptone in growth medium affects oxidative stress resistance in Escherichia coli.

To investigate the influence of the source of tryptone in the growth medium on the resistance of Escherichia coli to various types of oxidative stress. Cultures of Escherichia coli MG1655 were grown in Luria-Bertani (LB) medium at 37 degrees C to stationary phase, harvested, and subsequently subjected to various types of oxidative stress. A marked difference in oxidative stress sensitivity was observed depending on the origin of the tryptone in the LB medium used to grow the cultures. Cells harvested from LB containing tryptone from source x (LBx) were more sensitive to inactivation by the superoxide generating compound plumbagin and by t-butyl peroxide, and to growth inhibition by the lactoperoxidase enzyme system, than cells harvested from LB containing tryptone from source y (LBy). By monitoring expression of a panel of stress gene promotors linked to the gfp (green fluorescent protein) gene, and using Delta2-22 alkaline phosphatase as a probe for disulphide bridge formation from protein sulphydryl groups, it was demonstrated that a greater cytoplasmic oxidative stress existed in cells during growth in LBy than in LBx. Depending on the source of tryptone, bacteria may experience different levels of oxidative stress in tryptone-containing nonselective growth media. Although these levels of oxidative stress are subinhibitory, they may trigger a stress response that makes the bacteria more resistant to a subsequent exposure to a lethal or inhibitory level of oxidative stress. This work highlights the importance of controlling very subtle differences in composition of nonselective growth media in studies on bacterial physiology.

Expression of the trxA gene for thioredoxin 1 in Rhodobacter sphaeroides during oxidative stress.

Expression of the thioredoxin ( trxA) gene of Rhodobacter sphaeroides is regulated by oxidative stress at the transcriptional and post-transcriptional levels. All oxidative stress agents tested resulted in a moderate or strong increase of trxA mRNA levels, which was not due to increased mRNA stability. While the kinetics of increased trxA mRNA and of sodB mRNA, encoding superoxide dismutase, were similar after addition of tert-butyl hydroperoxide ( t-BOOH) or hydrogen peroxide (H(2)O(2)), different kinetics were observed after addition of diamide or paraquat, indicating the involvement of different stress responses in the regulation of these genes. The level of TrxA did not increase to the same extent as trxA mRNA levels. Furthermore, the addition of H(2)O(2) or t-BOOH led to increased turnover of the protein. Apparently, increased txA transcription compensated, at least in part, for the reduced stability of the protein. A strain expressing lower levels of thioredoxin 1 showed decreased resistance to diamide and H(2)O(2) but increased resistance to paraquat and t-BOOH compared to the wild-type. These data implicate the involvement of various systems in the response to different types of oxidative stress and the participation of thioredoxin 1 in the defense against oxidative stress caused by diamide or H(2)O(2).

Oxidative stress caused by inactivation of glutathione peroxidase and adaptive responses.

Reactive oxygen species (ROS) are generated as by-products of cellular metabolism, primarily in the mitochondria. When the cellular production of ROS exceeds the cell's antioxidant capacity, cellular macromolecules such as lipids, proteins and DNA can be damaged. Because of this, 'oxidative stress' is thought to contribute to aging and pathogenesis of a variety of human diseases. However, in the last 10-15 years, a considerable body of evidence has accumulated that ROS serve as subcellular messengers, and play a role in gene regulation and signal transduction pathways, which may be involved in defensive mechanisms against oxidative stress. This review focuses on oxidative stress caused by the inactivation of glutathione peroxidase (GPx), a major peroxide scavenging enzyme. GPx is inactivated by a variety of physiological substances, including nitric oxide and carbonyl compounds in vitro and in cell culture. Decreased GPx activity has also been reported in tissues where oxidative stress occurs in several pathological animal models. The accumulation of increased levels of peroxide resulting from inactivation of GPx may act as a second messenger and regulate expression of anti-apoptotic genes and the GPx itself to protect against cell damage. These findings suggest that GPx undergoes inactivation under various conditions such as nitroxidative stress and glycoxidative stress, and that these changes are a common feature of various types of oxidative stress which may be associated with the modification of redox regulation and cellular function.

Immunohistochemical study of the carotid body during acute hypoxia.

The carotid body is known to function as a chemoreceptor that is sensitive to inadequate oxygenation (hypoxia), hypercapnia and increased acidity in the arterial blood supply. Its regulatory effect is considered to be dependent on the ratio of oxygen to carbon dioxide. Differences in the plasma concentrations of these gases are measured by peripheral and central chemoreceptors located in the carotid body and brainstem, respectively. The carotid body consists basically of a parenchymal mass of clusters and strands of granular chromaffin type I glomus cells surrounded by nongranular type II glomus cells, with sinusoidal capillaries in close contact with both cell types. Afferent nerve fibers from the sinus branch of the glossopharyngeal nerve and postganglionic fibers of the sympathetic cervical ganglia form a dense network in contact with the type 1 cells. Some free nerve endings are present in the pericapillary space. Excitatory impulses generated in these fibers suspected to be true chemoreceptor nerve endings - are transmitted to the vasomotor center of the medulla oblongata. The glomus cells, classed as AUDP cells, are polygonal with light, round nuclei, abundant mitochondria and free ribosomes, a well developed ergastoplasm, and a Golgi apparatus. The expression of SP-22 protein is reported to be enhanced about 1.5- to 4.6-fold when bovine aortic endothelial cells (BAEC) are exposed to various types of oxidative stress, including mitochondrial respiratory inhibitors which increase the generation of superoxide in the mitochondria. BAEC with an increased level of the mitochondrial protein SP-22 resulting from mild oxidative stress become tolerant to subsequent intense oxidative stress. SP-22 is reported to be a member of the thioredoxin-dependent peroxidase family, suggesting that it may be one of the components of the antioxidant system in mitochondria, which are the major sites where reactive oxygen intermediates are generated (Araki etal. 1999)

Dysfunction of antioxidative enzymes and redox regulation under nitrosative stress and glycoxidative stress

We have previously shown that dicarbonyl compounds, the major by-products of the glycation reaction, selectively induce heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) in rat aortic smooth muscle cells (RASMCs) by increasing intracellular peroxide levels. The mechanism by which dicarbonyls increase peroxide levels, thus inducing HB-EGF, was previously examined and found to be via the inactivation of glutathione peroxidase (GPx), a major peroxidase scavenging enzyme. In this study, we demonstrate that the nitric oxide (NO) donor, S-nitroso-N-acetyl-dl-penicillamine (SNAP), also induces HB-EGF in a dose- and time-dependent manner in RASMCs. The mechanism of induction involves the direct inactivation of GPx by NO, resulting in the accumulation of intracellular peroxides, which are able to act as a second messenger and activate c-Jun NH2-terminal kinase (JNK) and c-Jun/AP-1 signaling pathways. Furthermore, when RASMCs, incubated with SNAP, are also treated with antisense HB-EGF oligonucleotide, the cells enter apoptosis, suggesting that the induction of HB-EGF could be an adaptive response as an autocrine protective factor against apoptosis by NO in RASMCs. These data indicate that GPx undergoes inactivation under conditions of nitroxidative stress and glycoxidative stress, and that these changes are a common feature of various types of oxidative stress which may be associated with the modification of redox regulation and cellular function.

Selenium, an Antioxidant Nutrient

Selenium is an essential constituent of a number of enzymes, some of which have antioxidant functions. Deficiency of the element in animals makes them susceptible to injury by certain types of oxidative stress. At least 1 human disease occurs only in selenium-deficient individuals. Therefore, it seems prudent to avoid selenium deficiency. The plasma (or serum) selenium concentration is often used to assess selenium nutritional status. A plasma selenium concentration of 8 micrograms/dL or greater in a healthy subject indicates that plasma selenoproteins are optimized and the subject is selenium replete. The Third National Health and Nutrition Examination Survey determined plasma selenium in 17,630 subjects in the United States. Its results indicate that more than 99% of the subjects studied were selenium replete. The Institute of Medicine has set the Recommended Dietary Allowance for selenium at 55 micrograms per day for adults. Since most estimates of selenium intake in the United States are 80 micrograms per day or greater, routine selenium supplementation is not recommended in the United States.

Free radicals and oxidative stress: targeted ESR measurement of free radicals

The detection of free radicals generated within the body may contribute to clarifying the pathophysiological role of free radicals in disease processes. As an appropriate procedure to examine the generation of free radicals in a biological system, electron spin resonance (ESR) has emerged as a powerful tool for detection and identification. A method for determination of oxygen radical scavenging activity using ESR and the spin trapping technique was developed. Oxygen radicals were trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) or alpha-phenyl-N-t-butylnitrone (PBN), and the DMPO or PBN spin adduct signal was measured quantitatively by an ESR spectrometer. The spin trapping method using ESR has also been reported for not only in vitro and ex vivo measurements but also in vivo measurements. In in vivo ESR, nitroxyl radical is being used as a spin trap well. ESR signal intensities of nitroxyl radical are measured after administration to animals and the signal decay rates of nitroxyl radical have reported to be influenced by various types of oxidative stress. With this method, it is possible to specify the type of radical or the location at which the free radicals are produced. The spin trapping method by in vivo ESR is an effective procedure for giving non-invasive measurements in animals. ESR imaging in the organs of live animals can also be obtained after injection of nitroxyl radicals as an imaging agent using ESR-computed tomography. In vivo ESR imaging has been established as a powerful technique for determining the spatial distribution of free radicals in living organs and tissues.

Pharmacological preconditioning with doxorubicin: Implications of heme oxygenase-1 induction in doxorubicin-induced hepatic injury in rats

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme into biliverdin, carbon monoxide, and iron. HO-1, an inducible form, is thought to contribute to resistance to various types of oxidative stress. Doxorubicin (DOX) produces clinically useful responses in a variety of human cancers. We reported previously that prior administration of DOX ameliorated subsequent hepatic ischemia and reperfusion injury. The aim of this study was to examine whether this pharmacological preconditioning was useful for another type of hepatic injury induced by a non-surgical method. When a high dose of DOX (10 mg/kg body weight) was administered directly to rat liver via the portal vein, serum aspartate transaminase (AST) and alanine transaminase (ALT) levels increased markedly 24 hr after the injection. Under this condition, zinc-protoporphyrin IX, a specific inhibitor of HO-1, caused both serum AST and ALT levels to be elevated further. When a low dose of DOX (5 mg/kg body weight) was administered to rats via the tail vein as pharmacological preconditioning 3 days before the injection of a high dose of DOX via the portal vein, the levels of serum AST and ALT in rats clearly were improved as compared with rats without the preconditioning. Expression of HO-1 in the liver was confirmed 3 days after the administration of a low dose of DOX. In addition, prior administration of zinc-protoporphyrin IX abolished the effect of DOX preconditioning. Immunohistochemical analysis showed that the positive staining of HO-1 protein induced by a low dose of DOX was localized to histiocytes infiltrating periportal areas. These results strongly suggest that pharmacological preconditioning with DOX may generally help to attenuate subsequent oxidant-induced hepatic injury.

Red wine antioxidants bind to human lipoproteins and protect them from metal ion-dependent and -independent oxidation.

Plant-derived polyphenols may exert beneficial effects on atherosclerosis and cardiovascular diseases, in part, because of their antioxidant properties. In this study we compared the effects of unbound (free) and lipoprotein-associated red wine components on in vitro antioxidant protection of human low-density lipoprotein (LDL). Preincubation of LDL (1 mg protein/mL) with 0-2.5% (v/v) red wine for 3 h at 37 degrees C followed by gel filtration to remove unbound red wine components resulted in a dose-dependent, up to 4-fold increase in LDL-associated antioxidant capacity (measured as Trolox equivalents). Similar results were obtained with high-density lipoprotein (HDL) and bovine serum albumin (BSA). Furthermore, LDL was subjected to oxidation by copper and aqueous peroxyl radicals (2,2'-azobis[2-amidinopropane] dihydrochloride, AAPH). Under both types of oxidative stress, LDL-associated and free red wine components significantly decreased oxidation of the lipoprotein's protein moiety (assessed by tryptophan fluorescence) and lipid moiety (assessed by thiobarbituric acid-reactive substances and conjugated dienes). Similar protective effects of red wine components were observed against HDL oxidation. In contrast, red wine exerted a pro-oxidant effect on copper-induced oxidation of BSA tryptophan residues, while protecting them from AAPH-induced oxidation. Ascorbate strongly enhanced the protective effect of red wine against copper-induced LDL oxidation, and had an additive effect against AAPH-induced oxidation. Our data indicate that red wine components bind to LDL and HDL and protect these lipoproteins from metal ion-dependent and -independent protein and lipid oxidation.

The Effect of Aging on Glutathione Peroxidase-I Knockout Mice—Resistance of the Lens to Oxidative Stress

Populations of control, C, and glutathione peroxidase-1 (GPx-1) knockout mice, K, were studied over a period of 2 years. No significant difference was observed between the C and K populations with respect to longevity, vitality, weight, lens biochemistry or morphology based on light and electron microscopy. It was concluded that under normal animal room barrier facilities, GPx-1 is not required. Furthermore, C and K lenses placed in organ culture and observed over a 24hr period were indistinguishable. Organ cultured C lenses degraded medium H2O2levels at only a slightly greater rate than K lenses and this did not appear to change with age. However, tertiary butyl hydroperoxide (TBHP) was degraded less effectively by K lenses and this deficiency increased with age. No indication of change in redox non-protein SH (equivalent to GSH) status was observed between C and K whole lenses or epithelial cell fractions. With H2O2stress, the drop in C and K non-protein SH was comparable and there was little change with age. Examination of the impact of photochemical stress with 1.5μM riboflavin and 4% O2upon choline transport indicated considerable damage with both C and K lenses, but little difference between the two populations until 1 or 2 years of age when the K lenses appear more vulnerable. With TBHP, the detrimental effect on the K lenses is greater and is observed earlier than with photochemical stress suggesting that the K lens membrane function is more susceptible to phospholipid hydroperoxide stress than are C lenses. Light and electron microscopy of the oxidative stressed lenses indicates significant damage which was generally somewhat greater in the K lenses. TBHP was a more potent oxidant than photochemically generated oxidants particularly at the anterior pole. The overall results suggest that under normal conditions, at any age, the lens does not require the presence of GPx-1 but depending on the type of oxidative stress, the enzyme may significantly contribute to its defense and this dependency may increase with age.

Salicylic acid response in rice: influence of salicylic acid on H 2O 2 accumulation and oxidative stress

We have studied the accumulation of hydrogen peroxide in rice leaves in response to salicylic acid (SA) treatment. H 2O 2 accumulation was localized in the veins. While the activity of the H 2O 2 degrading enzyme peroxidase was inhibited in response to SA, superoxide dismutase activity, which generates H 2O 2, did not show any change. An increase in the activity of glutathione reductase, a peroxide degrading enzyme, was observed upon SA treatment, similar to the response reported by accumulation of active oxygen species. In rice leaves transformed with CaMV-GUS fusions, we found that SA treatment induced transcriptional activation through as-1 element. As-1 has been implicated in protective mechanisms that operate during some types of oxidative stress and the hypersensitive response (HR). Expression of rice pathogenesis-related protein 5 (PR5), one of the PR genes associated with systemic acquired resistance, was induced by SA. This induction seems to be independent of the H 2O 2 accumulation induced by SA. Inoculation of rice leaves with the rice blast fungus, Magneporthe grisea, also led to the accumulation of H 2O 2 in the veins, suggesting the presence of common signals between SA and pathogen responses. Thus SA application seems to induce oxidative stress in rice through H 2O 2; a signal molecule implicated in biotic and abiotic stress responses.

Noninvasive study of radiation-induced oxidative damage using in vivo electron spin resonance

Nitroxyl radicals injected into a whole body indicate the disappearance of signal intensity of in vivo electron spin resonance (ESR). The signal decay rates of nitroxyl have reported to be influenced by various types of oxidative stress. We examined the effect of X-irradiation on the signal decay rate of nitroxyl in the upper abdomen of mice using in vivo ESR. The signal decay rates increased 1 h after 15 Gy irradiation, and the enhancement was suppressed by preadministration of cysteamine, a radioprotector. These results suggest that the signal decay of nitroxyl in whole mice is enhanced by radiation-induced oxidative damage. The in vivo ESR system probing the signal decay of nitroxyl could provide a noninvasive technique for the study of oxidative stress caused by radiation in a living body.

Using MT −/− mice to study metallothionein and oxidative stress

Mice with null mutations for metallothionein genes MT-1 and MT-2 were used to study the role that metallothionein plays in protecting cellular targets in vivo from oxidative stress. Wild-type (MT +/+) and MT-null (MT −/−) mice were treated with either saline or zinc and exposed to two types of oxidative stress: γ-irradiation or 2-nitropropane. There was no alteration in the antioxidant defense system (superoxide dismutase, catalase, or glutathione peroxidase and glutathione levels) to compensate for the lack of the metallothionein in the MT −/− mice. The amount of oxidative damage to liver DNA, lipids, and proteins were similar for the MT −/− and MT +/+ mice even though the levels of metallothionein in the livers of the saline- or zinc-pretreated MT +/+ mice were 5- to 100-fold greater than found in the MT −/− mice. To determine if metallothionein can protect mice from the lethal effects of ionizing radiation, the mean survivals of MT −/− and MT +/+ mice exposed to whole body γ-irradiation were measured and found to be similar. However, the mean survival increased significantly after zinc pretreatment for both the MT −/− and MT +/+ mice. These results demonstrate that tissue levels of metallothionein do not protect mice in vivo against oxidative stress.

Protective Role of Black Tea against Oxidative Damage of Human Red Blood Cells

The purpose of our study was to explore the possible scavenging property of black tea and catechins, the major flavonols of tea-leaf, against damage by oxidative stress. For this purpose, human red blood cell (rbc) was taken as the model and the oxidative damage was induced by a variety of inducers, e.g. phenylhydrazine (PHX), Cu2+-ascorbic acid, and xanthine/xanthine oxidase systems. Lipid peroxidation of pure erythrocyte membrane and of whole red blood cell could be completely prevented by black tea extract. Similarly, black tea provided total protection against degradation of membrane proteins. Finally, membrane fluidity studies as monitored by the fluorescent probe 1,6 diphenyl hexa 1,3,5-triene (DPH) showed considerable disorganization of its architecture that could be restored back to normal on addition of black tea or free catechins. Black tea extract in comparison to free catechins seemed to be a better protecting agent against various types of oxidative stress. Apparently, conversion of catechins to partially polymerized products such as theaflavin or thearubigin during ‘fermentation’ process for making black tea has no deleterious effect on its scavenging properties.

Changes in mitochondrial membrane potential during oxidative stress-induced apoptosis in PC12 cells.

We examined the effects of various types of oxidative stress on cell survival and on mitochondrial membrane potential (delta psi m) in PC12 cells transfected with BCL-2. Several types of oxidative stress such as exposure to hydrogen peroxide, 13-L-hydroperoxylinoleic acid, and xanthine + xanthine oxidase triggered apoptotic nuclear condensation and DNA fragmentation in normal PC12 cells. These types of oxidative stress induced significant increases in level of reactive oxygen species (ROS) before cell death. By contrast, BCL-2 prevented the apoptosis induced by these oxidative stresses. However, BCL-2 did not reduce ROS levels, indicating that it functions downstream of ROS generation. We measured delta psi m as a potential target of ROS during oxidative stress-induced cell death. Hydrogen peroxide, 13-L-hydroperoxylinoleic acid, and xanthine + xanthine oxidase induced a significant loss of delta psi m simultaneously with cell death. BCL-2 prevented the decrease in delta psi m as well as apoptosis induced by oxidative stress. These observations suggest that the oxidative stress triggers apoptosis associated with both increased generation of ROS and decreases in level of delta psi m and that BCL-2 prevents cell death as well as delta psi m but not ROS production.

Aging and superoxide dismutase activity in cerebrospinal fluid

We investigated superoxide dismutase (SOD) activity in human cerebrospinal fluid (CSF) as an index of the aging process in the central nervous system (CNS). The subjects were 61 individuals aged 21–77 years, comprising 24 men and 37 women without organic disorders of the nervous system. SOD activity in CSF was measured by the nitrite method modified by Oyanagui. The results showed that SOD activity in CSF gradually increased with age and that the values of SOD activity after the fifth decade were significantly higher than those in the third and fourth decades. It might suggest that the productivity of SOD in the CNS gradually increased with age due to stimulation of various types of oxidative stress which accumulated in vivo especially after the fifth decade.

A potential anti-oxidant protein in a ferrous iron-oxidizing Sulfolobus species

The production of a 25 kDa protein was greatly increased when a sulfur- and ferrous iron-oxidizing species of Sulfolobus was switched from growth on tetrathionate to growth on ferrous iron. The gene encoding the protein was cloned and sequenced. The predicted amino sequence showed significant similarity to those of the alkyl hydroperoxide reductase/thiol specific anti-oxidant family of proteins that appear to be involved in responses to certain types of oxidative stress.

A potential anti-oxidant protein in a ferrous iron-oxidizing Sulfolobus species.

The production of a 25 kDa protein was greatly increased when a sulfur- and ferrous iron-oxidizing species of Sulfolobus was switched from growth on tetrathionate to growth on ferrous iron. The gene encoding the protein was cloned and sequenced. The predicted amino sequence showed significant similarity to those of the alkyl hydroperoxide reductase/thiol specific anti-oxidant family of proteins that appear to be involved in responses to certain types of oxidative stress.

How Salmonella survive against the odds.

The enteric pathogen Salmonella typhimurium faces daunting odds during its voyages in the natural environment and through an infected host. It must manage stresses ranging from feast to famine, acid to base, and high to low osmolarity, among others, as well as counter various types of oxidative stress and a variety of antimicrobial peptides. The defenses used to survive these encounters can be specific or can provide cross protection to a variety of hostile conditions. Once inside a host, Salmonella spp. escape the extracellular environment and thus humoral immunity by invading professional and nonprofessional phagocytes in which a new set of challenges await. Some of these stresses are similar to those encountered in the natural environment (e.g. acid, starvation) but the bacterial response is complicated by the simultaneous occurrence of multiple stresses. S. typhimurium appears to sense various in vivo cues and responds by seducing the host signal-transduction pathways that are required to phagocytize the bacterial cell. The pathogen then calls upon components of its stress-response arsenal to survive the intracellular environment. These survival strategies enable the organism to persist in nature, where conditions are usually suboptimal, and equip the bacterium with pathogenic properties that, if successful, will provide it with a very rich and stress-free growth environment, a dead host.