ROS Damage Research Articles

The effect of advancing paternal age on semen parameters and seminal oxidative stress markers in infertile men

Advancing paternal age has been associated with increased frequency of spontaneous abortions and increased the risk of genetic diseases. The aim of our study was to investigate the effect of male ageing on sperm quality and seminal oxidative stress markers (ROS, TAC and sperm DNA damage).

The role of IL-6 in the radiation response of prostate cancer

BackgroundHormone-resistant (HR) prostate cancers are highly aggressive and respond poorly to treatment. IL-6/STAT3 signaling has been identified to link with the transition of HR and aggressive tumor behavior. The role of IL-6 in the radiation response of prostate cancer was investigated in the present study.Material and methodsThe murine prostate cancer cell line (TRAMP-C1) and the hormone-resistant cell sub-line, TRAMP-HR, were used to assess the radiation response using in vitro clonogenic assays and tumor growth delay in vivo. Biological changes following irradiation were investigated by means of experimental manipulation of IL-6 signaling. Correlations among IL-6 levels, tumor regrowth, angiogenesis and myeloid-derived suppressor cell (MDSC) recruitment were examined in an animal model.ResultsHR prostate cancer cells had a higher expression of IL-6 and more activated STAT3, compared to TRAMP-C1 cells. HR prostate cancer cells had a greater capacity to scavenge reactive oxygen species, suffered less apoptosis, and subsequently were more likely to survive after irradiation. Moreover, IL-6 expression was positively linked to irradiation and radiation resistance. IL-6 inhibition enhanced the radiation sensitivity of prostate cancer, which was associated with increased p53, RT-induced ROS and oxidative DNA damage. Furthermore, when mice were irradiated with a sub-lethal dose, inhibition of IL-6 protein expression attenuated angiogenesis, MDSC recruitment, and decreased tumor regrowth.ConclusionThese data demonstrate that IL-6 is important in the biological sequelae following irradiation. Therefore, treatment with concurrent IL-6 inhibition is a potential therapeutic strategy for increasing the radiation response of prostate cancer.

AB0026 Pathophysiological hypoxia affects both redox state and il-2 signaling of human cd4+ t cells and concomitantly impairs survival and proliferation

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory disease of diarthrodial joints, characterized by the infiltration of immune cells, alterations of cellular redox state and pathophysiological local tissue hypoxia (<1% O2).ObjectivesWe...

Antioxidant enzyme activities, malondialdehyde, and total phenolic content of PEG-induced hyperhydric leaves in sugar beet tissue culture

Hyperhydricity is a physiological abnormality that frequently affects shoots that are vegetatively propagated in vitro. In this study, sugar beet (Beta vulgaris L. cv. Felicita) shoot tip explants were cultured on Murashige and Skoog medium supplemented with different concentrations of polyethylene glycol (PEG) 6000. We observed that higher concentrations of PEG 6000 and longer exposure (up to 4 wk) resulted in increasing levels of hyperhydration as well as browning and/or blackening of tissues in culture. A comparison of hyperhydric shoots with controls on the 28th day showed a marked increase in the content of water, phenolics, and malondialdehyde (MDA), which was positively correlated with an increase in the accumulation of PEG 6000. Selected antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POX), and polyphenol oxidase (PPO) also increased in hyperhydric shoots, especially at lower concentrations of PEG 6000. Regression analysis indicated that strong linear relationships exist between SOD–APX (R 2 = 0.932), SOD–CAT (R 2 = 0.753), SOD–total phenolic content (R 2 = 0.966), APX–PPO (R 2 = 0.842), APX–total phenolic content (R 2 = 0.904), POX–CAT (R 2 = 0.751), and CAT–total phenolic content (R 2 = 0.806). Despite the correlation between different antioxidant enzymes and between the antioxidant enzymes and antioxidant compounds, was not able to prevent ROS damage in hyperhydric shoots. The negative correlation between SOD–MDA, POX–MDA, CAT–MDA, and MDA–total phenolics also indicated an increase in antioxidant enzyme activities, yet the increase in these antioxidant compound contents did not prevent lipid peroxidation of in vitro propagated beet shoots.

Critical role of TXNIP in oxidative stress, DNA damage and retinal pericyte apoptosis under high glucose: Implications for diabetic retinopathy

Diabetic retinopathy (DR) is characterized by early loss of retinal capillary pericytes and microvascular dysfunction. We recently showed that pro-oxidative stress and pro-apoptotic thioredoxin interacting protein (TXNIP) is significantly up-regulated in rat retinas in experimental diabetes and mediates inflammation and apoptosis. Therefore, we hypothesize here that TXNIP up-regulation in pericyte plays a causative role in oxidative stress and apoptosis under sustained high glucose exposure in culture. We maintained a rat retinal capillary pericyte cell line (TR-rPCT1) for 5 days under low glucose (LG, 5.5mM) or high glucose (HG, 25mM) with or without anti-oxidant N-acetylcysteine (5mM, NAC), Azaseine (2μM, AzaS), an inhibitor of TXNIP, and TXNIP siRNA (siTXNIP3, 20nM). The results show that HG increases TXNIP expression in TR-rPCT1, which correlates positively with ROS generation, protein S-nitrosylation, and pro-apoptotic caspase-3 activation. Furthermore, pericyte apoptosis is demonstrated by DNA fragmentation (alkaline comet assay) and a reduction in MTT survival assay. Treatment of TR-rPCT1 with NAC or an inhibition of TXNIP by AzaS or siTXNIP3 each reduces HG-induced ROS, caspase-3 activation and DNA damage demonstrating that TXNIP up-regulation under chronic hyperglycemia is critically involved in cellular oxidative stress, DNA damage and retinal pericyte apoptosis. Thus, TXNIP represents a novel gene and drug target to prevent pericyte loss and progression of DR.

A New Strategy for Intracellular Delivery of Enzyme Using Mesoporous Silica Nanoparticles: Superoxide Dismutase

We developed mesoporous silica nanoparticle (MSN) as a multifunctional vehicle for enzyme delivery. Enhanced transmembrane delivery of a superoxide dismutase (SOD) enzyme embedded in MSN was demonstrated. Conjugation of the cell-penetrating peptide derived from the human immunodeficiency virus 1 (HIV) transactivator protein (TAT) to mesoporous silica nanoparticle is shown to be an effective way to enhance transmembrane delivery of nanoparticles for intracellular and molecular therapy. Cu,Zn-superoxide dismutase (SOD) is a key antioxidant enzyme that detoxifies intracellular reactive oxygen species, ROS, thereby protecting cells from oxidative damage. In this study, we fused a human Cu,Zn-SOD gene with TAT in a bacterial expression vector to produce a genetic in-frame His-tagged TAT-SOD fusion protein. The His-tagged TAT-SOD fusion protein was expressed in E. coli using IPTG induction and purified using FMSN-Ni-NTA. The purified TAT-SOD was conjugated to FITC-MSN forming FMSN-TAT-SOD. The effectiveness of FMSN-TAT-SOD as an agent against ROS was investigated, which included the level of ROS and apoptosis after free radicals induction and functional recovery after ROS damage. Confocal microscopy on live unfixed cells and flow cytometry analysis showed characteristic nonendosomal distribution of FMSN-TAT-SOD. Results suggested that FMSN-TAT-SOD may provide a strategy for the therapeutic delivery of antioxidant enzymes that protect cells from ROS damage.

Foxo3-Mediated Redox Regulation Is Required for DNA Damage Response in Hematopoietic Stem Cells.

Abstract 2295Stringent regulation of redox status is critical to the control of hematopoietic stem cell (HSC) quiescence and to the maintenance of HSC pool. However mechanisms by which oxidative stress controls HSC quiescence versus cycling remain unknown. Foxo3 transcription factor is required for the regulation of HSC quiescence and for the maintenance of hematopoietic and leukemic stem cell pool. Redox regulation is key to the Foxo3 control of HSC pool. ROS accumulation in Foxo3 null HSC mediates in vivo activation of p53, and increased p21 expression leading to an arrest in the G2/M phase of cell cycle associated with loss of quiescence. We hypothesized that ROS may regulate HSC quiescence versus cycling via control of DNA damage repair program. To address this question, we examined whether Foxo3 is involved in DNA damage response of HSC. We first evaluated by immunostaining phosphorylation of histone H2AX variant (γH2AX), a hallmark sensor of DNA strand break, in LSK (Lin−Sca-1+c-Kit+) cells freshly isolated from Foxo3−/− bone marrow. We found the number of cells with nuclear γH2AX foci significantly increased in Foxo3−/− LSK cells (n=100; >5 foci/nuclei) in comparison with wild type (WT)-LSK. We subsequently confirmed and quantified these data by flow cytometry analysis of γH2AX. Together these analyses showed that loss of Foxo3 leads to increased γH2AX levels in LSK cells at the steady state. We next evaluated the presence of DNA breaks, by submitting Foxo3−/− versus WT LSK FACS-sorted cells to single-cell gel electrophoresis (Comet Assay). These investigations confirmed that LSK cells from Foxo3−/− mice accumulate DNA breaks at the steady state, as the percentage of comet shape cells (4 fold) and comet length (3 fold) were all increased in Foxo3 mutant LSK. We then asked whether the increased ROS accumulation had any direct role in damaging DNA in Foxo3−/− LSK. Using a fluorescent probe specific for the most common oxidative DNA damage lesion, the 8-hydroxyguanine base (8-OxoG), we further showed that Foxo3−/− LSK cells exhibit oxidative DNA damage. To further investigate the potential function of ROS in the control of HSC DNA damage response, we treated Foxo3−/− and WT mice for 14 days with the ROS scavenger N-acetyl-cysteine (NAC; 100 mg/Kg/day) in vivo. NAC treatment reduced by four fold γH2AX in Foxo3−/− LSK cells to levels similar to that in WT-LSK cells. Similarly, comet assay analysis of FACS-sorted LSK cells from NAC-treated WT and Foxo3−/− mice showed a two fold reduction of DNA breaks. These results suggest that increase in ROS damage DNA and triggers DNA damage response in Foxo3−/− LSK cells at the steady state. Additionally, expression of a number of genes involved in DNA damage repair including Xrcc5 (Ku80) and Xrcc6 (Ku70) was highly downregulated in both long-term-HSC (LT-HSC, LSK-CD150+CD48−) and LSK populations as evidenced by Q-RT-PCR on the Fluidigm™ microfluidics array technology. Together these results strongly suggest that Foxo3-mediated redox regulation is required for protection of DNA from accumulating damage at the steady state in HSC. We further investigated whether ROS-mediated activation of p53 in Foxo3 null HSCs limits the extent of accumulation of DNA damage in HSC. To address this question we crossed p53+/−Foxo3+/− double heterozygous animals to generate p53-Foxo3 double knockout mice. Loss of p53 in Foxo3−/− mice led to significant rise in lymphocyte counts and decrease in neutrophil counts in comparison with Foxo3−/−, indicating a potential shift in lineage determination from HSC. To our surprise, loss of one allele of p53 in Foxo3-null mice significantly reduced gH2AX staining and DNA breaks, as analyzed respectively by flow cytometry and comet assay of sorted LSK cells. While the rescue of DNA damage in Foxo3−/− HSCs as result of loss of p53 was unexpected it is not clear whether it is related to the impact on the fate of HSC. The clarification of these questions in future studies will be important for understanding mechanisms that control the emergence of leukemic stem cells. Together these studies suggest that Foxo3 guards DNA from damage in HSC at the steady state. In addition they indicate an important function for ROS modulation in the in vivo regulation of DNA damage response in HSC. Altogether understanding mechanisms that control ROS modulation of DNA damage response are likely to advance our understanding of the regulation of normal hematopoietic and leukemic stem cell quiescence. Disclosures:No relevant conflicts of interest to declare.

Effects of the ionic liquid [Omim]PF6 on antioxidant enzyme systems, ROS and DNA damage in zebrafish (Danio rerio)

The present study examined the toxic effects of the exposure to different concentrations of the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate for a 28-day period in zebrafish (Danio rerio) (sampled at 7, 14, 21 and 28d). The activities of antioxidant enzymes (superoxide dismutase and catalase), levels of reactive oxygen species and DNA damage in fish livers served as the indicators to assess the toxicity of [Omim]PF6 to zebrafish. The ionic liquid inhibited the activities of the antioxidant enzymes and caused the accumulation of ROS and DNA damage, and the results were concentration- and time-dependent. Male and female fish were tested separately and no differences were observed. The results showed that the ionic liquid could induce oxidative stress and DNA damage in zebrafish and that these effects could also accumulate over time.

A Reversible Early Oxidized Redox State That Precedes Macromolecular ROS Damage in Aging Nontransgenic and 3xTg-AD Mouse Neurons

The brain depends on redox electrons from nicotinamide adenine dinucleotide (reduced form; NADH) to produce ATP and oxyradicals (reactive oxygen species [ROS]). Because ROS damage and mitochondrial dysregulation are prominent in aging and Alzheimer's disease (AD) and their relationship to the redox state is unclear, we wanted to know whether an oxidative redox shift precedes these markers and leads to macromolecular damage in a mouse model of AD. We used the 3xTg-AD mouse model, which displays cognitive deficits beginning at 4 months. Hippocampal/cortical neurons were isolated across the age span and cultured in common nutrients to control for possible hormonal and vascular differences. We found an increase of NAD(P)H levels and redox state in nontransgenic (non-Tg) neurons until middle age, followed by a decline in old age. The 3xTg-AD neurons maintained much lower resting NAD(P)H and redox states after 4 months, but the NADH regenerating capacity continuously declined with age beginning at 2 months. These redox characteristics were partially reversible with nicotinamide, a biosynthetic precursor of NAD+. Nicotinamide also protected against glutamate excitotoxicity. Compared with non-Tg neurons, 3xTg-AD neurons had more mitochondria/neuron and lower glutathione (GSH) levels that preceded age-related increases in ROS levels. These GSH deficits were again reversible with nicotinamide in 3xTg-AD neurons. Surprisingly, low macromolecular ROS damage was only elevated after 4 months in the 3xTg-AD neurons if antioxidants were removed. The present data suggest that a more oxidized redox state and a lower antioxidant GSH defense can be dissociated from neuronal ROS damage, changes that precede the onset of cognitive deficits in the 3xTg-AD model.

Bezielle Selectively Targets Mitochondria of Cancer Cells to Inhibit Glycolysis and OXPHOS

Bezielle (BZL101) is a candidate oral drug that has shown promising efficacy and excellent safety in the early phase clinical trials for advanced breast cancer. Bezielle is an aqueous extract from the herb Scutellaria barbata. We have reported previously that Bezielle was selectively cytotoxic to cancer cells while sparing non-transformed cells. In tumor, but not in non-transformed cells, Bezielle induced generation of ROS and severe DNA damage followed by hyperactivation of PARP, depletion of the cellular ATP and NAD, and inhibition of glycolysis. We show here that tumor cells' mitochondria are the primary source of reactive oxygen species induced by Bezielle. Treatment with Bezielle induces progressively higher levels of mitochondrial superoxide as well as peroxide-type ROS. Inhibition of mitochondrial respiration prevents generation of both types of ROS and protects cells from Bezielle-induced death. In addition to glycolysis, Bezielle inhibits oxidative phosphorylation in tumor cells and depletes mitochondrial reserve capacity depriving cells of the ability to produce ATP. Tumor cells lacking functional mitochondria maintain glycolytic activity in presence of Bezielle thus supporting the hypothesis that mitochondria are the primary target of Bezielle. The metabolic effects of Bezielle towards normal cells are not significant, in agreement with the low levels of oxidative damage that Bezielle inflicts on them. Bezielle is therefore a drug that selectively targets cancer cell mitochondria, and is distinguished from other such drugs by its ability to induce not only inhibition of OXPHOS but also of glycolysis. This study provides a better understanding of the mechanism of Bezielle's cytotoxicity, and the basis of its selectivity towards cancer cells.

251: Numeracy and literacy in pregnant women with pregestational diabetes

251: Numeracy and literacy in pregnant women with pregestational diabetes

S-Adenosylhomocysteine enhances DNA damage through increased β-amyloid formation and inhibition of the DNA-repair enzyme OGG1b in microglial BV-2 cells

S-Adenosylhomocysteine (SAH) is a risk factor for neurodegenerative diseases such as Alzheimer's disease, for which β-Amyliod (Aβ) formation is a major risk factor. We recently showed that SAH increases Aβ formation in mouse microglial BV2 cells. Here, we show that incubation of BV2 cells with SAH (0–500 nM) for 6–24 h sequentially increased Aβ formation, ROS and DNA damage measured as 8-oxo-deoxyguanosine (8-oxo-dG) levels. Pre-incubation of BV2 cells with 20 μM β-secretase inhibitor IV for 30 min followed by incubation with SAH (500 nM) markedly decreased Aβ formation and 8-oxo-dG levels. Treatment with SAH for 24 h concentration-dependently inhibited DNA methyltransferase (DNMT1) activity and inhibited DNMT1 binding to Sp1 site of 8-oxoG-DNA glycosylases I (OGG1) promoter and OGG1 protein and mRNA expression at 24 h; the latter effect was attributed to hypomethylation of the OGG1 gene promoter, because pre-incubation of cells with betaine (1.0 mM for 30 min) markedly prevented the inhibition of OGG1 protein expression induced by SAH. Overall, we demonstrate that SAH increases DNA damage in BV-2 cells possible by increased Aβ formation leading to increased formation of ROS. Furthermore, the DNA damage is enhanced by SAH through inhibition of DNMT1 activity and hypomethylation of OGG1 gene promoter.

Novel Oligonucleotide Carrier as Scavenger for Reactive Oxygen Species

A novel oligonucleotide carrier which can scavenge ROS is described. The synthesized graft polymer is composed of a PEG segment and a TEMPO-containing hydrophobic segment for scavenging ROS. This graft polymer can form a PIC through electrostatic interaction with oligonucleotides such as siRNA. The amount of ROS was monitored by fluorescence measurements using H₂ DCFDA as a probe, and it was confirmed that the ROS level was effectively suppressed. The cellular uptake of PIC containing the fluorescence-labeled oligonucleotide was evaluated by fluorescence microscopy. Delivered siRNA suppressed the expression of the mRNA. The prepared graft copolymer is thus a promising candidate as a novel oligonucleotide carrier which also reduces ROS damage generated by cationic polymer carriers.

Functional conservatism among Drosophila simulans flies experiencing different thermal regimes and mitochondrial DNA introgression

Drosophila simulans possesses three different mitochondrial haplotypes (siI, II and III) that are nonrandomly geographically subdivided with a 3% interhaplogroup variation. The aim of this study was to determine whether perturbation of mitochondrial metabolism and ROS management by temperature variation and mtDNA introgression would influence the development of aerobic capacity and the intensity of oxidative stress in D. simulans at different ages. Environmental temperature divergences during development had few impacts on metabolic capacities. Our data suggested strong functional conservatism of mitochondrial haplotypes between the D. simulans lines studied. This conservatism was expressed by the low divergences in either mitochondrial or ROS buffering enzyme activities, or even markers of ROS damage even after disruption of coevolved genomes. Disruption of coevolved mitochondrial and nuclear genomes through mtDNA introgression induced no clear divergence on metabolic phenotype at any state of development. Reduction of cytochrome c oxidase activity that was observed after introgression of one mitochondrial haplotype will require further investigation to delineate whether it is associated with any modification of mito-nuclear interactions.

Genetic and biochemical analysis of base excision repair complexes participating in radiation-induced ROS damage repair

This work is part of the joint research project 'radiation-induced DNA damage' of the KVSF, a BMBF Initiative (maintenance of radiation biology expertise in Germany). The focus of the research is the mechanism of DNA repair, specifically damage repair aspects arising from radiation-induced reactive oxygen species production. The authors will systematically look at potential accessory proteins associated with primarily base excision repair using molecular and biochemical methods. The authors hope to gain knowledge on the initial response mechanisms to varying sources and doses of radiation. By using a highly sensitive marker system, it is intended to achieve a greater resolution of responses induced at lower doses. The work is of relevance for different human diseases caused by defects in DNA repair, e.g. spontaneous and radiation-related cancer. Beyond this, the risk of low radiation doses, for example, in the workplace is of relevance for radiation protection policy and decision-making thereof.

Life-long caloric restriction: Effect on age-related changes in motoneuron numbers, sizes and apoptotic markers

The first purpose of this study was to determine the effect of advanced age (31 months) on the number of motoneurons in the lumbar enlargement of the rat and to determine if motoneurons die via apoptosis with age. The second purpose was to determine if caloric restriction (CR) would attenuate any observed age-related changes in motoneuron numbers or markers of apoptosis and ROS damage. Using immunohistochemistry to identify choline acetyltransferase (ChAT) – positive motoneurons in the ventro-lateral horn larger than 15 μm in diameter and having a clear soma and nucleus were sized and counted. Western blots were used to quantify markers of ROS, apoptosis and autophagy in the ventral horn of the lumbar enlargement. The results suggest that the total number of motoneurons in the rat lumbar enlargement does not significantly decrease with age. Also at the time of sacrifice, aged motoneurons were actively undergoing apoptosis through the intrinsic pathway, in a caspase-dependent manner. CR was able to attenuate the increase in body weight, body weight/muscle mass ratio and the level of activate caspase-3 associated with age. CR also reduced the level of heat shock protein 27, oxoguanine glycosylase 1, cytochrome c and LC3B-I.

Abstract 4390: The p16INK4A tumor suppressor regulates cellular oxidative stress

Abstract Melanoma, a malignant tumor of melanocytes, is a potentially lethal form of skin cancer linked to both environmental and genetic factors. Mutations or deletions in the cyclin-dependent kinase inhibitor p16INK4A are associated with multiple cancer types, but more commonly found in melanoma tumors and specifically associated with familial melanoma predisposition. Although p16 is thought to function as a tumor suppressor by negatively regulating the cell cycle, it remains unclear why genetic compromise of p16 predisposes to melanoma rather than other cancers. Here we describe a novel role for p16 in regulating oxidative stress in several cell types, including melanocytes. Compared to keratinocytes and fibroblasts, we also found increased ROS levels basally and following treatment with H2O2. Expression of p16 was rapidly upregulated following UV-irradiation in melanocytes, and in response to H2O2-induced oxidative stress in a p38 stress-activated protein kinase-dependent manner. Knockdown of p16 using siRNA increased intracellular ROS and oxidative (8-oxoguanine) DNA damage which was further enhanced by H2O2 treatment. Elevated ROS were also observed in p16-depleted human keratinocytes, and in whole skin and dermal fibroblasts from p16-deficient mice. ROS in p16-deficient fibroblasts were normalized by expression of exogenous p16. Finally, p16-mediated suppression of ROS could not be attributed to upregulation of antioxidant enzymes or the role of p16 in cell cycle regulation. These findings suggest a potential alternate tumor-suppressor function of p16 as an endogenous regulator of carcinogenic intracellular oxidative stress. The increased susceptibility of melanocytes to oxidative stress may explain why compromise of p16 predisposes to melanoma over other cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4390.

Why Vitamin E Therapy Fails for Treatment of Alzheimer's Disease

ROS damage in the AD brain is widely reported at the levels of nucleic acids [1], protein [2] and lipids [3]. ROS damage is also associated with heart disease, cancer and aging. Consequently, numerous clinical trials of the lipid soluble anti-oxidant, vitamin E, have been conducted for prevention [4] and treatment [5] of age-related morbidity and mortality. The meta-analysis by Miller et al.[5] clearly shows that among 19 clinical trials, only the smaller trials show either an increase or a decrease in all-cause mortality and that the overall effect is near zero. By organizing these studies into a dose-response curve, a significant increase in all-cause mortality was observed for vitamin E doses above 400 IU/day. In an earlier trial of vitamin E treatment for AD at the high dose 2000 IU/day, there was no effect of vitamin E on mini-mental state of moderately severe AD patients, despite delays in nursing home placement [6]. In a trial of MCI patients, Petersen et al. [7] found that even early vitamin E treatment failed to improve cognition. These results prompted Lloret et al. [8] to introduce the novel concept of stratifying AD patients into vitamin E respondents and non-respondents, based on measures of plasma GSSG, the oxidized form of the common antioxidant glutathione (GSH). At the borderline detrimental dose of 800 IU/day [5], about half of the patients failed to respond to vitamin E with lower plasma GSSG; they showed a lower MMSE score after 6 months that suggested a 13% decline in cognitive performance [8]. The other half of the patients for whose GSSG decreased with vitamin E treatment did not significantly change their original MMSE score. Unfortunately, the study was not large enough to detect a decline in MMSE for treatment with placebo. Also provocative from Lloret et al.’s report was a strong negative correlation between GSSG and MMSE, but most of the effect was due to 4 of 19 AD patients with a 5–10% drop in GSSG in response to vitamin E.

Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

BackgroundWelding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles.ResultsOur results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage.ConclusionIncrease in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of fume generated, particle size, and elapsed time after generation of the welding exposure are significant factors in radical generation and particle deposition these factors should be considered when developing protective strategies.

Generation of Hydroxyl Radicals in the Reaction of Ferritin with Hydrogen Peroxide

ROS are involved in normal cell processes such as cell signaling and proliferation. However, when present in excess amounts, ROS damage cellular biomolecules and have been implicated in the etiology of a broad variety of diseases, including athero-sclerosis, diabetes, neurodegenerative diseases, chronic inflam-matory disease, and cancer and aging.