Related Reactive Oxygen Species Research Articles

Glut4 expression in pro-atherogenic monocytes is associated with estrogen induced ROS formation

Abstract Background Glucose transporter (GLUT) 4 was shown to be expressed on monocytes with dynamic alterations. Moreover, increased formation of monocyte related reactive oxygen species (ROS) is an important marker for atherosclerosis and estrogen is known to increase ROS. However, the impact of estrogen on human monocytes have not been investigated. This is of great importance as a high number of aging women receive hormone replacement therapy (HRT) due to meno-pause symptoms. This was shown to be associated with high risk for ischemic events. In this study, we investigated the impact of estrogen on human monocytes about membrane expression of GLUT4 and ROS formation. Methods In this pilot study, we investigated human leukocytes from 88 healthy volunteers (54 female and 34 male) and 114 patients (56 female and 58 male) treated in the department of Cardiology, Pneumology and Vascular medicine, University Hospital Düsseldorf. Buffy coat was extracted out of whole blood by centrifugation and analysed by flow-cytometry. Amount of CD14+ and CD16+ monocytes was measured in % of all leukocytes in all participants. ROS and GLUT4 expression were assessed for monocyte type in dependence from increasing estrogen concentrations in a sub cohort by in-vitro incubation representing physiological peak and HRT concentrations (0, 500 and 2000 pM). Results Mean age of healthy volunteers was 31,2 years. Mean age of patients was 75,9 years. In patients, 51% were male, 58% had arterial hypertension, 33% diabetes mellitus type II, 16% were smokers and 19% were obese. Antiatherogenic monocytes (CD16+) were stable in males but decreased with age in females (female: r=-0.3130 p=0.0010; male: r=-0.1011 p=0.3946). In contrast, pro-atherogenic monocytes (CD14+) increased with age in females (female: r=0.4013 p=<0.0001; male: r=0.09135 p=0.4389). Increasing estrogen concentrations induced ROS formation in all monocytes in a dose dependent manner (0 – 947±124, 500 - 1312±258, 2000 - 1248±629 geometric mean, p=0.0327 [one-way ANOVA]). Separation in CD14+ and CD16+ monocytes revealed that this effect was only driven by increase in CD14+ monoctyes (0 - 1021±325, 500- 1160±239, 2000 – 513 geometric mean, p=0.0179), whereby CD16+ monocytes did not show relevant increase. GLUT4 membrane expression was inversely related to increasing estrogen levels with decrease in CD14+ (0 - 578±81, 500- 498±55, 2000- 507±41 geometric mean, p=0.0131) and numerical reduction in CD16+ monocytes by high estrogen levels (0- 592±77, 500 - 544±80, 2000- 537±72 geometric mean, p=0.0784) Conclusion In this study, we could show that high estrogen levels induce decrease of GLUT4 membrane expression in human monocytes. This might be associated with increased ROS formation in pro-atherogenic CD14+ monocytes which are already increased with age in women. This might reflect a relevant mechanism for the increased rate of ischemic events by HRT.

EFFECTS OF SINGLET OXYGEN THERAPY MAY BE СONPLIMENTED BY NITRIC MONOOXIDE: MASS SPECTROMETRIC FINDINGS

The purpose of this study was to clarify the composition of the gas flow from the singlet oxygen generator and its features relative to air as a carrier gas. The mass spectra of the exhaust gases were recorded by a quadrupole mass spectrometer Extorr XT 300(M) Series VGA with a resolution of 1 atomic unit of mass (aem). The spectrum of the gas flow was analyzed in the standard operating mode of the "Airnergy" generator, as well as when shielding the aqueous medium from radiation with an impermeable membrane for it. The spectra were evaluated by the presence of characteristic bands of particle mass. It is revealed that the treatment of the air flow in the "Airnergy" apparatus, including its humidification and exposure to UV radiation, significantly transforms its qualitative and quantitative composition. In the outgoing stream, a decrease in the level of carbon dioxide and molecular oxygen is detected with a simultaneous increase in the concentration of nitric monoxide (NO). This circumstance has a special biological significance, since the presence of this compound in the gas stream from the singlet oxygen generator can complement and transform the effects of this reactive oxygen species in relation to biological systems.

Cytosine methylations in the promoter regions of genes involved in the cellular oxidation equilibrium pathways affect rice heat tolerance

BackgroundHigh temperatures, particularly at night, decrease rice yield and quality. As high nighttime temperatures (HNTs) become increasingly frequent due to climate change, it is imperative to develop rice crops that tolerate HNTs. DNA methylation may represent a potential avenue for HNT-tolerant rice strain development, as this mechanism regulates gene activity and cellular phenotype in response to adverse environmental conditions without changing the nucleotide sequence.ResultsAfter HNT exposure, the methylation patterns of cytosines in the CHH context differed noticeably between two coisogenic rice strains with significantly different levels in heat tolerance. Methylation differences between strains were primarily observed on successive cytosines in the promoter or downstream regions of transcription factors and transposon elements. In contrast to the heat-sensitive rice strain, the regions 358–359 bp and 2–60 bp downstream of two basal transcriptional factors (TFIID subunit 11 and mediator of RNA polymerase II transcription subunit 31, respectively) were fully demethylated in the heat-tolerant strain after HNT exposure. In the heat-tolerant strain, HNTs reversed the methylation patterns of successive cytosines in the promoter regions of various genes involved in abscisic acid (ABA)-related reactive oxygen species (ROS) equilibrium pathways, including the pentatricopeptide repeat domain gene PPR (LOC_Os07g28900) and the homeobox domain gene homeobox (LOC_Os01g19694). Indeed, PRR expression was inhibited in heat-sensitive rice strains, and the methylation rates of the cytosines in the promoter region of PRR were greater in heat-sensitive strains as compared to heat-tolerant strains.ConclusionsAfter HNT exposure, cytosines in the CHH context were more likely than cytosines in other contexts to be methylated differently between the heat-sensitive and heat-tolerant rice strains. Methylation in the promoter regions of the genes associated with ABA-related oxidation and ROS scavenging improved heat tolerance in rice. Our results help to clarify the molecular mechanisms underlying rice heat tolerance.

Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning

Air filtration has become an essential need for passive pollution control. However, most of the commercial air purifiers rely on dense fibrous filters, which have good particulate matter (PM) removal capability but poor biocidal effect. Here we present the photocatalytic bactericidal properties of a series of metal-organic frameworks (MOFs) and their potentials in air pollution control and personal protection. Specifically, a zinc-imidazolate MOF (ZIF-8) exhibits almost complete inactivation of Escherichia coli (E. coli) (>99.9999% inactivation efficiency) in saline within 2 h of simulated solar irradiation. Mechanistic studies indicate that photoelectrons trapped at Zn+ centers within ZIF-8 via ligand to metal charge transfer (LMCT) are responsible for oxygen-reduction related reactive oxygen species (ROS) production, which is the dominant disinfection mechanism. Air filters fabricated from ZIF-8 show remarkable performance for integrated pollution control, with >99.99% photocatalytic killing efficiency against airborne bacteria in 30 min and 97% PM removal. This work may shed light on designing new porous solids with photocatalytic antibiotic capability for public health protection.

EGFR tyrosine kinase inhibition decreases cardiac remodeling and SERCA2a/NCX1 depletion in streptozotocin induced cardiomyopathy in C57/BL6 mice

AimEpidermal growth factor receptor (EGFR) related reactive oxygen species (ROS) generation results in myocardial damage. We aimed to investigate the role of gefitinib (EGFR-tyrosine kinase inhibitor) in diabetic cardiomyopathy (DbCM). MethodDbCM was induced by injecting streptozotocin (55 mg/kg for 5 consecutive days) to C57/BL6 mice intraperitoneally. Diabetic C57/BL6 mice (fasting blood glucose level ≥ 250 mg/dl) were allocated into four study groups and treated with two doses of gefitinib (30 mg/kg and 350 mg/kg per day) as well as ramipril (3 mg/kg/day) for four weeks. Key findingsWe observed a significant correlation between persistent hyperglycaemia with cardiac remodeling and alterations in myocardial architecture. Gefitinib significantly prevented lipid peroxidation (MDA), damage of antioxidant enzymes like superoxide dismutase (SOD), Catalase, glutathione (GSH) and thioredoxin reductase (TrxR). Gefitinib also prevented hypertrophy of myocardium evidenced by reduced heart weight to body weight ratio and TGF‑β related collagen deposition. Gefitinib maintained cardiac biomarkers like lactate dehydrogenase (LDH), Creatine Kinase‑MB, brain natriuretic peptide (BNP) and cardiac Troponin‑I (cTroponinI) indicating reduced myocardial damage. Decreased sarcoplasmic endoplasmic reticulum Ca2 + ATPase2a (SERCA2a) and sodium‑calcium exchanger-1 (NCX1) protein depletion after gefitinib administration indicated improved Ca2+ homeostasis during myocardial contractility. Histopathology and transmission electron microscopy clearly showed almost normal myofibrils and mitochondrial arrangements in gefitinib treated mice. SignificanceOur findings suggest that gefitinib protects myocardial damage in DbCM via balancing oxidant-antioxidant system, decreased collagen deposition as well as improved CKMB, BNP, cTroponinI and SERCA2a/NCX-1. Thereby, it indicated that gefitinib may be a potential therapeutic drug for treating DbCM.

344 Human spermatozoa function is positively influenced by Vitamin D

It is reported that vitamin D (VitD) deficiency is associated with male reproductive failure. The objective of this study was to evaluate the direct effect of different concentrations of VitD on the functional parameters of human spermatozoa. Spermatozoa were selected by swim-up from 30 patients, and divided into 5 groups of 6 patients each: Control Group (C) and 4 groups that were exposed to increasing concentrations (nM) of VitD: 0.01VitD; 0.1VitD; 1VitD and 10VitD. Plasma membrane integrity, presence of reactive oxygen species, mitochondrial membrane potential, and loss of plasma membrane cholesterol were assessed by flow cytometry. Calcium transport was observed by confocal microscopy. Spermatozoa presented better plasma membrane integrity in 1VitD group (64.80 ± 7.94) when compared to groups C (48.52 ± 8.82, p = 0.0150); 0.01VitD (42.40 ± 7.36, p = 0.0015) and 0.1VitD (42.33 ± 8.22, p = 0.0015). 10VitD group (59.65 ± 5.45) also had a greater percentage of spermatozoa with higher plasma membrane integrity in relation to 0.01VitD (42.40 ± 7.36, p = 0.0150) and 0.1VitD (42.33 ± 8.22, p = 0.0150) groups. The production of reactive oxygen species in spermatozoa supplemented with VitD was lower in group 1VitD (15.78 ± 3.04) when compared to groups C (23.48 ± 1.99, p = 0.0042); 0.01VitD (22.53 ± 4.67, p = 0.0115) and 0.1VitD (21.42 ± 4.43, p = 0.0354). The 10VitD group (15.67 ± 0.43) also had lower production of reactive oxygen species in relation to groups C (23.48 ± 1.99, p = 0.0040), 0.01VitD (22.53 ± 4.67, p = 0.0113) and 0.1VitD (21.42 ± 4.43, p = 0.0354). There was no difference in the mitochondrial membrane potential of the spermatozoa among the groups studied. Nevertheless, The loss of plasma membrane cholesterol was higher in all VitD groups [0.01VitD (1.05 ± 0.60); 0.1VitD (2.47 ± 1.77); 1VitD (4.60 ± 2.85) and 10VitD (3.22 ± 292)] when compared to Controls (19.23 ± 4.2, p < 0.0001). The calcium influx was higher in group C (7137.00 ± 4380.00) when compared to group 0.01VitD (1046.00 ± 499.70), as well as in group 10VitD (9309.00 ± 5600.00) when compared to groups 0.01VitD (1046.00 ± 499.70), 0.1VitD (1096.00 ± 389.50) and 1VitD (1160.00 ± 424.40, p = 0.0006).

Canine Macrophage DH82 Cell Line As a Model to Study Susceptibility to Trypanosoma cruzi Infection.

Trypanosoma cruzi is an obligatory intracellular protozoan parasite, and it is the etiological agent of Chagas’ disease that is endemic in the Americas. In addition to humans, a wide spectrum of mammals can be infected by T. cruzi, including dogs. Dogs develop acute and chronic disease, similar to human infection. T. cruzi can infect almost all cell types and after cell invasion, the metacyclics trypomastigotes localize in the cytoplasm, where they transform into amastigotes, the replicative form of T. cruzi in mammals. After amastigote multiplication and differentiation, parasites lyse host cells and spread through the body by blood circulation. In this work, we evaluated the in vitro ability of T. cruzi to infect a canine macrophage cell line DH82 compared with RAW264.7, a murine tissue culture macrophage. Our results have shown that the T. cruzi is able to infect, replicate and differentiate in DH82 cell line. We observed that following treatment with LPS and IFN-γ DH82 cells were more resistant to infection and that resistance was not related reactive oxygen species production in our system. In this study, we also found that DH82 cells became more susceptible to T. cruzi infection when cocultured with apoptotic cells. The analysis of cytokine production has showed elevated levels of the TGF-β, IL-10, and TNF-α produced by T. cruzi-infected canine macrophages. Additionally, we demonstrated a reduced expression of the MHC class II and CD80 by infected DH82 cell line.

Vagal afferents, sympathetic efferents and the role of the PVN in heart failure.

Sympatho-excitation is a characteristic of cardiovascular disease including heart failure (HF). The paraventricular nucleus of the hypothalamus (PVN) is an important site for central integration of sympathetic outflow. Atrial volume receptors (AVRs) in the wall of the right atrium transduce cardiovascular variables (pressure/volume) into an input that is integrated centrally, in for example, the PVN. Descriptions of the location and structure of the AVRs as well as the molecular mechanism initiating transduction remain scarce, nevertheless preautonomic neurons of the PVN have been consistently identified as making a significant contribution to the sympatho-excitation evident in HF. Furthermore, excitatory and inhibitory interactions within the PVN determine sympathetic tone. A nitric oxide dependent GABAergic inhibition sets the prevailing sympathetic output from the PVN, which in HF becomes dysregulated. Inflammation and oxidative stress have been recognised as possible triggers to the disinhibition. The actions of proinflammatory cytokines and reactive oxygen species in relation to the signalling pathways, which are important in generating sympathetic tone are discussed, as well as the contribution these might make to abnormal control of the sympathetic nervous system in cardiovascular disease.

Effect of native Trichoderma viride and Pseudomonas fluorescens on the development of Cuscuta campestris on chickpea, Cicer arietinum

Cuscuta campestris Yuncker is a serious parasite on several leguminous crops including chickpea in India. Chickpea is an important pulse crop in India and severe incidence of Cuscuta may result in yield loss of about 85.7%. Management of Cuscuta is very difficult because of their intricate relationship with the host, wide host range and lack of resistant genes in the host. Thus induced systemic resistance (ISR) by plant growth promoting microbes (microbial elicitors) may be an effective alternative method for the management of Cuscuta. In the current study, to induce systemic resistance, native isolates of Trichoderma viride Pers. and Pseudomonas fluorescens Flügge were used as seed treatments and foliar spray on chickpea and then infested with C. campestris. Salicylic acid and thiobenzamidazole (synthetic elicitors) were used as standard inducing agents for comparison. Results indicated that fresh seeds of C. campestris germinated rapidly even without scarification and that the germination was not influenced by the proximity of the seeds to the host. Seed treatment followed by foliar sprays with the bioagents and synthetic elicitors induced at 20 and 40 days after sowing (DAS) induced increased production of defense enzymes in chickpea (Cicer arietinum L.) and thus delayed the development (1.8-5 days) and flowering (2.4-4.2 days) of C. campestris. Treatment with both the elicitors also resulted in the enhanced activities of scavengers of enzymes related reactive oxygen species (ROS). Thus the above work would help in the integration of the application of bioagents for effective management of Cuscuta in chickpea.

Superoxide dismutase deficiency impairs olfactory sexual signaling and alters bioenergetic function in mice.

Oxidative stress (an overproduction of reactive oxygen species in relation to defense mechanisms) may restrict investment in life history traits, such as growth, reproduction, lifespan, and the production of sexual signals to attract mates. The constraint on sexual signaling by oxidative stress is of particular interest because it has been proposed as a mechanism ensuring that only good-quality males produce the most attractive sexual signals. Despite these predictions, evidence supporting this theory is, at best, equivocal. We used a superoxide dismutase knockout mouse to demonstrate that oxidative stress directly impairs investment in morphological (preputial glands) and molecular (major urinary proteins) components of olfactory signaling essential for mate attraction. By maintaining males in a much more competitive environment than usual for mouse laboratory experiments, we also revealed a range of phenotypes of superoxide dismutase deficiency not observed in previous studies of this mouse model. This range included impaired bioenergetic function, which was undetectable in the control environment of this study. We urge further examination of model organisms in seminatural conditions and more competitive laboratory environments, as important phenotypes can be exposed under these more demanding conditions.

Antioxidant and drug metabolism

The production of physiological amount of free radical is essential to fight against an unfavorable environment. The free radicals like nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. In higher organisms, NO and ROS regulates vascular tone, oxygen tension in control of ventilation and erythropoietin production.1 Free radicals activate a signal transduction from membrane receptors, for example ROS is essential for tissue factor protein expression in endothelial cells, TNF-γ-induced vascular cell adhesion protein 1 (VCAM-1) in vascular smooth muscle cells (VSMCs), tyrosine phosphorylation in fibroblasts and lymphocytes, etc. Similarly reactive nitrogen species (RNS) is important in norepinephrine-induced prostacycline release in hypothalamus, formations of synaptic connections in olfactory receptor neurons, N-methyl-D-aspartic acid (NMDA) receptor activity in cortical neurons, etc.2

Biological importance of reactive oxygen species in relation to difficulties of treating pathologies involving oxidative stress by exogenous antioxidants

Findings about involvement of reactive oxygen species (ROS) not only in defense processes, but also in a number of pathologies, stimulated discussion about their role in etiopathogenesis of various diseases. Yet questions regarding the role of ROS in tissue injury, whether ROS may serve as a common cause of different disorders or whether their uncontrolled production is just a manifestation of the processes involved, remain unexplained. Dogmatically, increased ROS formation is considered to be responsible for development of the so-called free-radical diseases. The present review discusses importance of ROS in various biological processes, including origin of life, evolution, genome plasticity, maintaining homeostasis and organism protection. This may be a reason why no significant benefit was found when exogenous antioxidants were used to treat free-radical diseases, even though their causality was primarily attributed to ROS. Here, we postulate that ROS unlikely play a causal role in tissue damage, but may readily be involved in signaling processes and as such in mediating tissue healing rather than injuring. This concept is thus in a contradiction to traditional understanding of ROS as deleterious agents. Nonetheless, under conditions of failing autoregulation, ROS may attack integral cellular components, cause cell death and deteriorate the evolving injury.

Physiological adaptations to reproduction I. Experimentally increasing litter size enhances aspects of antioxidant defence but does not cause oxidative damage in mice

Life history theory suggests that investment in reproduction can trade off against growth, longevity and both reproduction and performance later in life. One possible reason for this trade-off is that reproduction directly causes somatic damage. Oxidative stress, an overproduction of reactive oxygen species in relation to cellular defences, can correlate with reproductive investment and has been implicated as a pathway leading to senescence. This has led to the suggestion that this aspect of physiology could be an important mechanism underlying the trade-off between reproduction and lifespan. We manipulated female reproductive investment to test whether oxidative stress increases with reproduction in mice. Each female's pups were cross-fostered to produce litters of either two or eight, representing low and high levels of reproductive investment for wild mice. No differences were observed between reproductive groups at peak lactation for several markers of oxidative stress in the heart and gastrocnemius muscle. Surprisingly, oxidative damage to proteins was lower in the livers of females with a litter size of eight than in females with two pups or non-reproductive control females. While protein oxidation decreased, activity levels of the antioxidant enzyme superoxide dismutase increased in the liver, suggesting this may be one pathway used to protect against oxidative stress. Our results highlight the need for caution when interpreting correlative relationships and suggest that oxidative stress does not increase with enhanced reproductive effort during lactation.

Au@PtAg core/shell nanorods: tailoring enzyme-like activities via alloying

Pt nanoparticles (NPs) have been reported to demonstrate four kinds of enzyme-like activity including superoxide dismutase (SOD), catalase, oxidase and peroxidase. Some of these activities interfere with each other. For instance, as antioxidant enzyme mimics, their SOD and catalase activities are very helpful in scavenging related reactive oxygen species (ROSs). However, their oxidase-like and/or peroxidase-like activities may simultaneously oxidize some natural antioxidants, thus compromising the final anti-oxidation efficacy. Fine tuning different enzyme-like activities is therefore very important to realize the optimization of their functions. In this paper, our effort is focused in this direction by tailoring the electronic structure of Pt NPs via alloying with Ag. All four enzyme-like activities are found to be weakened by an increased Ag percentage in the alloy, as witnessed by decreased values of Kcat. The variation in the electronic structure also changes the substrate affinity. Introducing silver into Pt weakens the affinity for H2O2, which affects the limit of detection (LOD) for H2O2 and products with H2O2 involved. In contrast to Fe3O4 MNPs, for peroxidase-like activity, hydroxyl radicals are not involved in the oxidation of chromogenic substrates for the alloy nanostructures.

Oxidative stress in inflammation‐based gastrointestinal tract diseases: Challenges and opportunities

Oxygen free radicals in excessively high amounts are all very reactive chemically and can impose a detrimental influence on living organisms by provoking "oxidative stress" that can damage major cellular constituents. The latter includes the cell membrane, cytoplasmic proteins, and nuclear DNA. Conversely, nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) when present in low amounts play an important role as regulatory mediators in signaling processes, through which, paradoxically, many ROS-mediated responses can protect the cells against oxidative stress by induction of "redox homeostasis." Therefore, diseases associated with free radical overproduction are provoked by "blazed ROS productions" far beyond the host's capacity to quench. Free radicals have been implicated in the pathogenesis of diverse gastrointestinal (GI) diseases including gastroesophageal reflux disease (GERD), gastritis, enteritis, colitis and associated cancers as well as pancreatitis and liver cirrhosis. This article provides an overview of the role of oxidative stress in inflammation-based GI tract diseases, including reflux esophagitis, Helicobacter pylori-associated gastritis, non-steroidal anti-inflammatory drug-induced enteritis, ulcerative colitis, and associated colorectal cancer. The challenging issue that ROS can contribute to diverse gastrointestinal dysfunction, or manifest dual roles in cancer promotion or cancer suppression will also be discussed for the opportunity to enhance understanding of inflammation-based GI diseases.

Application of profluorescent nitroxides for measurements of oxidative capacity of combustion generated particles

Oxidative stress caused by generation of free radicals and related reactive oxygen species (ROS) at the sites of deposition has been proposed as a mechanism for many of the adverse health outcomes associated with exposure to particulate matter (PM). Recently, a new profluorescent nitroxide molecular probe (BPEAnit) developed at QUT was applied in an entirely novel, rapid and non-cell based assay for assessing the oxidative potential of particles (i.e. potential of particles to induce oxidative stress). The technique was applied on particles produced by several combustion sources, namely cigarette smoke, diesel exhaust and wood smoke. One of the main findings from the initial studies undertaken at QUT was that the oxidative potential per PM mass significantly varies for different combustion sources as well as the type of fuel used and combustion conditions. However, possibly the most important finding from our studies was that there was a strong correlation between the organic fraction of particles and the oxidative potential measured by the PFN assay, which clearly highlights the importance of organic species in particle-induced toxicity.

The Mitochondrial Production of Reactive Oxygen Species in Relation to Aging and Pathology

Abstract: Mitochondria are known to be strong producers of reactive oxygen species (ROS) and, at the same time, particularly susceptible to the oxidative damage produced by their action on lipids, proteins, and DNA. In particular, damage to mtDNA induces alterations to the polypeptides encoded by mtDNA in the respiratory complexes, with consequent decrease of electron transfer, leading to further production of ROS and thus establishing a vicious circle of oxidative stress and energetic decline. This deficiency in mitochondrial energetic capacity is considered the cause of aging and age‐related degenerative diseases. Complex I would be the enzyme most affected by ROS, since it contains seven of the 13 subunits encoded by mtDNA. Accordingly, we found that complex I activity is significantly affected by aging in rat brain and liver mitochondria as well as in human platelets. Moreover, due to its rate control over aerobic respiration, such alterations are reflected on the entire oxidative phosphorylation system. We also investigated the role of mitochondrial complex I in superoxide production and found that the one‐electron donor to oxygen is most probably the Fe‐S cluster N2. Short chain coenzyme Q (CoQ) analogues enhance ROS formation, presumably by mediating electron transfer from N2 to oxygen, both in bovine heart SMP and in cultured HL60 cells. Nevertheless, we have accumulated much evidence of the antioxidant role of reduced CoQ10 in several cellular systems and demonstrated the importance of DT‐diaphorase and other internal cellular reductases to reduce exogenous CoQ10 after incorporation.

Follicular reactive oxygen species in relation to oocyte maturity and fertilization outcome

Objective: To measure the amount of reactive oxygen species in periovulatory follicular fluids and investigate the relationship to oocyte maturity and fertilization outcome. Design: Retrospective study. Materials and Methods: Clear follicular aspirates were collected at oocyte recovery from thirty women superovulated using the gonadotrophin releasing hormone analogue (GnRH-a)/ human menopausal gonadotrophin (HMG) regimen. Ninety aspirates were collected from separate follicles, examined for oocytes and immediately tested for reactive oxygen species using the Luminometer (AutoLumat LB 953) and a kinetics curve created for each sample. Measured data as total integral of measured signals and peak maximum in counted photons per second (cps) were correlated to oocyte maturity and fertilization. Results: No significant difference was found between reactive oxygen species in follicles yielding mature or immature oocytes nor between those yielding oocytes that fertilized, did not fertilize or showed polyspermic fertilization.However, there appeared to be a difference between the peak maximum value of reactive oxygen species in follicular fluids of fertilized oocytes compared to unfertilized oocytes but this did not reach statistical significance (p=0.075). Conclusion: This is the first report detecting follicular reactive oxygen species on a quantitative basis. However, further studies are still needed in this respect to define more precisely their role in follicular development, oocyte maturation and fertilization.

Free radicals in the physiological control of cell function.

At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, however, nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. Many of the ROS-mediated responses actually protect the cells against oxidative stress and reestablish "redox homeostasis." Higher organisms, however, have evolved the use of NO and ROS also as signaling molecules for other physiological functions. These include regulation of vascular tone, monitoring of oxygen tension in the control of ventilation and erythropoietin production, and signal transduction from membrane receptors in various physiological processes. NO and ROS are typically generated in these cases by tightly regulated enzymes such as NO synthase (NOS) and NAD(P)H oxidase isoforms, respectively. In a given signaling protein, oxidative attack induces either a loss of function, a gain of function, or a switch to a different function. Excessive amounts of ROS may arise either from excessive stimulation of NAD(P)H oxidases or from less well-regulated sources such as the mitochondrial electron-transport chain. In mitochondria, ROS are generated as undesirable side products of the oxidative energy metabolism. An excessive and/or sustained increase in ROS production has been implicated in the pathogenesis of cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and other diseases. In addition, free radicals have been implicated in the mechanism of senescence. That the process of aging may result, at least in part, from radical-mediated oxidative damage was proposed more than 40 years ago by Harman (J Gerontol 11: 298-300, 1956). There is growing evidence that aging involves, in addition, progressive changes in free radical-mediated regulatory processes that result in altered gene expression.

In vitro resistance of Burkholderia cepacia complex isolates to reactive oxygen species in relation to catalase and superoxide dismutase production.

The Burkholderia cepacia complex comprises groups of genomovars (genotypically distinct strains with very similar phenotypes) that have emerged as important opportunistic pathogens in cystic fibrosis (CF) patients. The inflammatory response against bacteria in the airways of CF individuals is dominated by polymorphonuclear cells and involves the generation of oxidative stress, which leads to further inflammation and tissue damage. Bacterial catalase, catalase-peroxidase and superoxide dismutase activities may contribute to the survival of B. cepacia following exposure to reactive oxygen metabolites generated by host cells in response to infection. In the present study the authors investigated the production of catalase, peroxidase and SOD by isolates belonging to various genomovars of the B. cepacia complex. Production of both catalase and SOD was maximal during late stationary phase in almost all isolates examined. Native PAGE identified 13 catalase electrophoretotypes and two SOD electrophoretotypes (corresponding to an Fe-SOD class) in strains belonging to the six genomovars of the B. cepacia complex. Seven out of 11 strains displaying high-level survival after H(2)O(2) treatment in vitro had a bifunctional catalase/peroxidase, and included all the genomovar III strains examined. These isolates represent most of the epidemic isolates that are often associated with the cepacia syndrome. The majority of the isolates from all the genomovars were resistant to extracellular O(-)(2), while resistance to intracellularly generated O(-)(2)was highly variable and could not be correlated with the detected levels of SOD activity. Altogether the results suggest that resistance to toxic oxygen metabolites from extracellular sources may be a factor involved in the persistence of B. cepacia in the airways of CF individuals.