Source Of Oxidative Damage Research Articles

Electronic Excitation Response of DNA to High-Energy Proton Radiation in Water.

The lack of molecular-level understanding for the electronic excitation response of DNA to charged particle radiation, such as high-energy protons, remains a fundamental scientific bottleneck in advancing proton and other ion beam cancer therapies. In particular, the dependence of different types of DNA damage on high-energy protons represents a significant knowledge void. Here we employ first-principles real-time time-dependent density functional theory simulation, using a massively parallel supercomputer, to unravel the quantum-mechanical details of the energy transfer from high-energy protons to DNA in water. The calculations reveal that protons deposit significantly more energy onto the DNA sugar-phosphate side chains than onto the nucleobases, and greater energy transfer is expected onto the DNA side chains than onto water. As a result of this electronic stopping process, highly energetic holes are generated on the DNA side chains as a source of oxidative damage.

Does Neuraxial Anesthesia as General Anesthesia Damage DNA? A Pilot Study in Patients Undergoing Orthopedic Traumatological Surgery.

The human organism is exposed daily to many endogenous and exogenous substances that are the source of oxidative damage. Oxidative damage is one of the most frequent types of cell component damage, leading to oxidation of lipids, proteins, and the DNA molecule. The predominance of these damaging processes may later be responsible for human diseases such as cancer, neurodegenerative disease, or heart failure. Anesthetics undoubtedly belong to the group of substances harming DNA integrity. The goal of this pilot study is to evaluate the range of DNA damage by general and neuraxial spinal anesthesia in two groups of patients undergoing orthopedic traumatological surgery. Each group contained 20 patients, and blood samples were collected before and after anesthesia; the degree of DNA damage was evaluated by the comet assay method. Our results suggest that general anesthesia can cause statistically significant damage to the DNA of patients, whereas neuraxial anesthesia has no negative influence.

Keap1-Mediated Nrf2 Dysfunction as a Source of Oxidative Damage in Human Diabetic Wounds

Purpose: Despite advancements in disease management and wound therapies, chronic diabetic ulcers represent the leading cause of non-traumatic lower extremity amputations in the United States. The Nrf2 master antioxidant transcription factor has emerged as a promising target for combatting the oxidative stress underlying these wounds. We have previously implicated Keap1-mediated Nrf2 dysfunction in delayed diabetic wound healing, and as a therapeutic target, in mice. However, whether these findings extend to human diabetic wounds remains unknown. Methods: Intact skin (S) and wound tissue (W) was obtained from diabetic (D) and nondiabetic (ND) patients, and analyzed for reactive oxygen species (ROS) end products (8-OhDG DNA assay), and with immunohistochemistry (IHC), qPCR (gene expression), and western blot (protein expression). Student’s t-tests were used for statistical analysis. Results: Both DS and DW contained more than 2-fold ROS end products, respectively, compared to NDS and NDW (2.344 vs. 1.117 ng/mL and 4.648 vs. 1.866 ng/mL, p<0.008). DS and DW exhibited 2-fold and 2.5-fold decreases in epidermal Nrf2 staining, respectively, compared to NS and NW (p<0.001). Keap1-the cytoplasmic Nrf2 repressor-was overexpressed in DW when compared to NDW (p<0.04). DW showed a 75% reduction in nuclear Nrf2 protein expression (p<0.02) as compared to NDW. DW also exhibited a 25% relative reduction in gene expression of MnSOD, a key Nrf2 downstream antioxidant enzyme, and 5-fold decrease in epidermal cytoplasmic MnSOD staining compared to NDW, p<0.03. Conclusion: Here, we implicate Nrf2 dysfunction in impaired redox homeostasis and consequent oxidative damage in both human diabetic skin and diabetic wounds as compared to nondiabetics. We also identify Keap1 as a likely mediator of impaired healing in diabetic wounds. These results recapitulate our previous findings in mice, further validating this critical pathway as a promising target for understanding and treating diabetic wound healing. Disclosure J.A. David: None. A.P. Villarreal-Ponce: None. S.A. Abdou: None. D.L. Sultan: None. W.J. Rifkin: None. J. Kwong: None. P.S. Rabbani: None. D. Ceradini: None.

Scalp Condition Impacts Hair Growth and Retention via Oxidative Stress.

Conventionally, the medical focus has been either on hair loss or the condition of the scalp in terms of specific dermatological diseases. Indeed, the proximate structural arrangement of the scalp and hair leads to an interdependent relationship between the two. While protective benefits of the hair to the scalp are obvious, the role of the scalp as an incubatory environment for the preemergent hair fiber has largely been ignored. In fact, there is a wealth of observational data on specific dermatological conditions of the scalp providing evidence for the role of the scalp condition in supporting the production of healthy hair. Oxidative stress, the inability of the body to sufficiently counteract the sources of oxidation, is prevalent in many skin conditions, including normal skin aging. On the scalp, the hair appears to be impacted prior to emergence, and oxidative stress appears to play a role in premature hair loss. The scalp commensal organism, Malassezia, has been recognized to be a source of oxidative damage. Therefore, hair care products, specifically shampoos, with active Malassezia inhibitory agents, such as zinc pyrithione, tend to reduce premature hair loss, besides the known benefits in treating specific dermatologic scalp pathologies, and therefore should represent an integral part of every treatment regimen for hair loss, even in individuals not showing symptoms of scalp pathologies.

Oxidative Damage and Genetic Toxicity Induced by DBP in Earthworms (Eisenia fetida).

Di-n-butyl phthalate (DBP) is one of the most ubiquitous plasticizers used worldwide. However, it has negatives effects on the soil, water, atmosphere, and other environmental media and can cause serious pollution. According to the artificial soil test and previous studies, this study was conducted to evaluate the toxicity of earthworms induced by DBP at different concentrations (0, 0.1, 1.0, 10, and 50mgkg-1) on the 7th, 14th, 21st, and 28th days of exposure. The variations in the antioxidant activities of enzymes, such as catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and glutathione-S-transferase (GST), in the amounts of malondialdehyde (MDA) and reactive oxygen species (ROS) and in the amount of DNA damage were measured to evaluate the toxic impact of DBP in earthworms. Upon exposure to DBP, the SOD, CAT, POD, and GST activities were significantly increased, with the exception of the 0.1mgkg-1 treatment dose. High concentrations of DBP (10 and 50mgkg-1) induced superfluous ROS to be produced and caused the MDA content to increase significantly. Therefore, we proposed that DBP led to DNA damage in earthworm coelomocytes in a dose-dependent manner, which means that DBP is a source of oxidative damage and genetic toxicity in earthworms.

Irradiation of Red Blood Cells and Alloimmunization.

Animal models suggest that red blood cell (RBC) damage incurred during storage can increase immunogenicity to some RBC antigens. We hypothesized that RBC irradiation, a source of oxidative damage, may result in higher RBC alloimmunization rates among transfusion recipients. Individuals receiving 1 or more gamma-irradiated RBC units, with follow-up antibody screening, were studied. We recorded diagnosis at the time of first irradiated RBC-unit transfusion, total irradiated RBCs received, and alloantibodies detected before and after irradiated RBC transfusion. The alloimmunization rate for patients receiving irradiated RBCs was 1.9% (3/154); this rate was not significantly different from the rate of 2.5% (5/200) derived from a control group that had undergone transfusion with nonirradiated RBCs ( P > .99). Most of the study subjects (83/154 [53.9%]) did not harbor an immunosuppressive disorder at the time of transfusion of irradiated RBCs, with postoperative bleeding (36/83 [43.4%]) being the most common diagnosis. This analysis provides reassurance that irradiated RBCs are not more immunogenic in patients with immunosuppression than in patients with immunocompetence.

Biology of Extreme Radiation Resistance: The Way of Deinococcus radiodurans

The bacterium Deinococcus radiodurans is a champion of extreme radiation resistance that is accounted for by a highly efficient protection against proteome, but not genome, damage. A well-protected functional proteome ensures cell recovery from extensive radiation damage to other cellular constituents by molecular repair and turnover processes, including an efficient repair of disintegrated DNA. Therefore, cell death correlates with radiation-induced protein damage, rather than DNA damage, in both robust and standard species. From the reviewed biology of resistance to radiation and other sources of oxidative damage, we conclude that the impact of protein damage on the maintenance of life has been largely underestimated in biology and medicine.

Mitochondrial Thiols in Antioxidant Protection and Redox Signaling: Distinct Roles for Glutathionylation and Other Thiol Modifications

The mitochondrial matrix contains much of the machinery at the heart of metabolism. This compartment is also exposed to a high and continual flux of superoxide, hydrogen peroxide, and related reactive species. To protect mitochondria from these sources of oxidative damage, there is an integrated set of thiol systems within the matrix comprising the thioredoxin/peroxiredoxin/methionine sulfoxide reductase pathways and the glutathione/glutathione peroxidase/glutathione-S-transferase/glutaredoxin pathways that in conjunction with protein thiols prevent much of this oxidative damage. In addition, the changes in the redox state of many components of these mitochondrial thiol systems may transduce and relay redox signals within and through the mitochondrial matrix to modulate the activity of biochemical processes. Here, mitochondrial thiol systems are reviewed, and areas of uncertainty are pointed out, focusing on recent developments in our understanding of their roles. The areas of particular focus are on the multiple, overlapping roles of mitochondrial thiols and on understanding how these thiols contribute to both antioxidant defenses and redox signaling. Recent technical progress in the identification and quantification of thiol modifications by redox proteomics means that many of the questions raised about the multiple roles of mitochondrial thiols can now be addressed.

Origins of Age-Related DNA Damage and Dietary Strategies for Its Reduction

The polyunsaturated fatty acids in biological membranes serve as both the target and source of oxidative damage and can be regarded as the most unstable class of biomolecules in the body. Lipid peroxides arising from both spontaneous and enzymatic oxidation of polyunsaturated fatty acids are the major source of endogenous DNA damage linked to various age-related pathologies and initiating carcinogenesis. Here we describe the major types of lipid peroxide-derived DNA adducts and propose a simple dietary strategy to reduce their formation. This may be particularly beneficial to the aging organism, which has progressively impaired natural protective systems.

Lipid peroxidation as a source of oxidative damage in Helicobacter pylori: Protective roles of peroxiredoxins

Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase ( ahpC) and the bacterioferritin comigratory protein ( bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain ( ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe–S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.

Cataract formation in a strain of rats selected for high oxidative stress

The primary purpose of this study was to define the clinical and morphological features of cataractogenesis in the OXYS strain of rats that generate excess reactive oxygen species. Rats were sequentially examined from birth to the development of mature cataracts with slit lamp biomicroscopy. Morphology of selected stages of cataract development was studied using light and transmission electron microscopy (TEM), immunohistochemical localization of the lipid peroxidation product 4-hydroxynonenal (HNE) and fluorescent antibody labeling for DNA oxidation products. Lenses from age-matched normal rats were used as controls. OXYS rats developed cataracts as young as two weeks of age with progression to maturity by 1 year. Clinically, cataracts appeared initially either as nuclear or sub-capsular cortical changes and progressed to pronounced nuclear cataracts within months. TEM confirmed the light microscopic impression of region-specific alterations in both fiber cell cytoplasmic protein matrix and membrane structure. The outer adult nuclear region showed extensive cellular damage similar to osmotic cataracts, which is consistent with the postulated high uptake of glucose in the OXYS strain. The adult and outer fetal nuclear cells displayed several types of focal damage. The inner fetal and embryonic nuclear cells demonstrated textured cytoplasm, suggesting protein degradation or redistribution. Staining for HNE was increased in epithelium, cortex and nucleus compared to control lenses. Fluorescent antibody probes demonstrated increased levels of DNA oxidation products in OXYS rat lenses compared to age-matched controls. Fourier analysis of nuclear cytoplasm revealed significant components with corresponding sizes greater than 100 nm and, using a new theoretical approach, the texturing of the cytoplasm was shown to be sufficient to cause opacification of the nucleus. The OXYS rat appears to be an ideal model for oxidative stress cataractogenesis. The potential oxidative damage observed is extensive and characteristic of the developmental region. The source of oxidative damage may in part be a response to elevated levels of glucose. Because oxidative stress is thought to be a major factor in cataract formation in both diabetic and non-diabetic aging humans, this animal model may be a useful tool in assessing efficacy of antioxidant treatments that may slow or prevent cataract formation.

Catalase protects cardiomyocyte function in models of type 1 and type 2 diabetes.

Many diabetic patients suffer from a cardiomyopathy that cannot be explained by poor coronary perfusion. Reactive oxygen species (ROS) have been proposed to contribute to this cardiomyopathy. Consistent with this we found evidence for induction of the antioxidant genes for catalase in diabetic OVE26 hearts. To determine whether increased antioxidant protection could reduce diabetic cardiomyopathy, we assessed cardiac morphology and contractility, Ca(2+) handling, malondialdehyde (MDA)-modified proteins, and ROS levels in individual cardiomyocytes isolated from control hearts, OVE26 diabetic hearts, and diabetic hearts overexpressing the antioxidant protein catalase. Diabetic hearts showed damaged mitochondria and myofibrils, reduced myocyte contractility, slowed intracellular Ca(2+) decay, and increased MDA-modified proteins compared with control myocytes. Overexpressing catalase preserved normal cardiac morphology, prevented the contractile defects, and reduced MDA protein modification but did not reverse the slowed Ca(2+) decay induced by diabetes. Additionally, high glucose promoted significantly increased generation of ROS in diabetic cardiomyocytes. Chronic overexpression of catalase or acute in vitro treatment with rotenone, an inhibitor of mitochondrial complex I, or thenoyltrifluoroacetone, an inhibitor of mitochondrial complex II, eliminated excess ROS production in diabetic cardiomyocytes. The structural damage to diabetic mitochondria and the efficacy of mitochondrial inhibitors in reducing ROS suggest that mitochondria are a source of oxidative damage in diabetic cardiomyocytes. We also found that catalase overexpression protected cardiomyocyte contractility in the agouti model of type 2 diabetes. These data show that both type 1 and type 2 diabetes induce damage at the level of individual myocytes, and that this damage occurs through mechanisms utilizing ROS.

Pyrimidine 5' nucleotidase deficiency.

Pyrimidine 5' nucleotidase deficiency.

Immunohistochemical Localization of Xanthine Oxidase in Human Retina

Xanthine oxidase has been established as an important source of oxygen free radicals in ischemia-reperfusion injury. It has been localized in many different tissues such as heart and intestine, but it has not yet been localized in the eye. Xanthine oxidase was detected using immunohistochemistry on paraformaldehyde/glutaraldehyde fixed cryosections. Antibodies used included rabbit antibovine xanthine oxidase antibody and rabbit antihuman xanthine oxidase antibody. Xanthine oxidase was detected in the capillary endothelium cells of blood vessels in the retina of bovine and post mortem human eyes. Whole mount preparation of human retinas showed xanthine oxidase present throughout the small capillary network. Furthermore, whole mounts showed that xanthine oxidase was present in cones. This was confirmed by using mouse anticalbindin antibody for co-labelling. It is possible that xanthine oxidase can be a source of oxidative damage in the retina following ischemia-reperfusion injury.

Free radicals generated by xanthine oxidase mediate pancreatitis-associated organ failure.

In the present study we evaluate the possibility that xanthine oxidase released by damaged pancreas could act as a source of oxidative damage in systemic tissues during the early stages of acute pancreatitis. This was accomplished by evaluating the effects of xanthine oxidase inhibition with oxypurinol infused into the portal vein. Under these conditions, we inhibited the enzyme before it reached the liver and other distant organs, without inducing changes in the severity of pancreatic damage. Results indicate that pancreatitis parallels increases in xanthine oxidase activity in plasma. Superoxide radicals generated by this enzyme appears to be involved in the decrease of reduced glutathione levels in the plasma and liver. In addition, xanthine oxidase inhibition prevents the infiltration of neutrophils into the lungs. We conclude that oxygen free radicals generated by xanthine and xanthine oxidase released to the bloodstream are involved in the systemic organ failure associated with acute pancreatitis.