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Oxygen Species (oxygen + species)

Distribution by Scientific Domains
Life Sciences45%
Medical Sciences40%
Chemistry9%
6 Other Domains6%
Distribution within Life Sciences
Plant Science20%
Neuroscience15%
Cell & Molecular Biology13%
Cell Biology8%
Genomics & Proteomics6%
22 Other Subdomains38%

Kinds of Oxygen Species

  • active oxygen species
  • intracellular reactive oxygen species
    		•
  • mitochondrial reactive oxygen species
  • other reactive oxygen species
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  • radical oxygen species
  • reactive oxygen species
    		•

    Terms modified by Oxygen Species

  • oxygen species formation
  • oxygen species generation
    		•
  • oxygen species level
  • oxygen species production
    		•

    Selected Abstracts

    INTERPLAY OF REACTIVE OXYGEN SPECIES AND NITRIC OXIDE IN THE PATHOGENESIS OF EXPERIMENTAL LEAD-INDUCED HYPERTENSION

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2007
    ND Vaziri
    SUMMARY 1Lead is a common environmental and industrial toxin that can cause a variety of acute and chronic illnesses. For example, chronic exposure to low levels of lead has been shown to raise arterial pressure and promote renal and cardiovascular complications. 2Several mechanisms have been identified by which chronic lead exposure can cause hypertension and cardiovascular disease. In recent years, increasing evidence has emerged pointing to the role of oxidative stress as a major mediator of lead-induced hypertension. 3The present article provides an overview of the published studies on this subject. [source]

    DOES THE INTRARENAL REACTIVE OXYGEN SPECIES/ANGIOTENSINOGEN/RENIN,ANGIOTENSIN SYSTEM AXIS PLAY AN IMPORTANT ROLE IN THE PROGRESSION OF CHRONIC KIDNEY DISEASE?

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2009
    Yoshio Konishi
    No abstract is available for this article. [source]

    SEQUENTIAL ACTIVATION OF THE REACTIVE OXYGEN SPECIES/ANGIOTENSINOGEN/RENIN,ANGIOTENSIN SYSTEM AXIS IN RENAL INJURY OF TYPE 2 DIABETIC RATS

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2008
    Kayoko Miyata
    SUMMARY 1The present study was performed to test the hypothesis that the reactive oxygen species (ROS),angiotensinogen (AGT),renin angiotensin system (RAS) axis is sequentially activated in the development of diabetic nephropathy in Zucker diabetic fatty (ZDF) obese rats. 2Genetic pairs of male ZDF obese and control ZDF lean rats (n = 12 of each species) were killed every 3 weeks from 12 to 21 weeks of age (n = 6 at each time point). 3The ZDF obese rats developed diabetes mellitus at 12 weeks. At that time, urinary excretion rates of 8-isoprostane were similar between the groups; however, urinary 8-isoprostane levels were significantly increased at 15 weeks in ZDF obese rats compared with controls (36 ± 6 vs 15 ± 2 ng/day, respectively). At 15 weeks, protein levels of cortical angiotensinogen were similar between groups; however, cortical angiotensinogen levels were significantly increased at 18 weeks in ZDF obese rats compared with controls (relative ratio of 2.32 ± 0.21 vs 1.00 ± 0.20, respectively). At 12 weeks, angiotensin (Ang) II-like immunoreactivity was similar between groups in both the glomeruli and tubules; however, AngII-like immunoreactivity was increased significantly at 21 weeks in ZDF obese rats compared with controls (relative ratios of 1.98 ± 0.55 vs 1.00 ± 0.03, respectively, for glomeruli and 1.58 ± 0.16 vs 1.00 ± 0.13, respectively, for tubules). Moreover, at 21 weeks, the desmin-positive area in the glomeruli (0.63 ± 0.08 vs 0.22 ± 0.05%) and Masson's trichrome stain-positive area in the interstitium (4.97 ± 0.05 vs 3.18 ± 0.41%) were significantly increased in ZDF obese rats compared with controls, even though these differences had not been observed earlier. 4These data suggest that the sequential activation of the ROS,AGT,RAS axis plays an important role in the development of diabetic nephropathy in ZDF obese rats. [source]

    Fluorescent Nanoprobes: Fluorescent Gold Nanoprobe Sensitive to Intracellular Reactive Oxygen Species (Adv. Funct.

    ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
    Mater.
    On page 1884, H. Lee and co-workers report fluorescent gold nanoprobes sensitive to reactive oxygen species (ROS). Using nanoparticle surface energy transfer between gold nanoparticles and end-dopamine modified fluorescein-hyaluronic acid conjugates, gold nanoprobes are created with extreme sensitivity to intracellular ROS. The cover image shows real time monitoring of intracellular ROS generation within macrophage cells via fluorescence recovery of the nanoprobes. [source]

    Fluorescent Gold Nanoprobe Sensitive to Intracellular Reactive Oxygen Species

    ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
    Hyukjin Lee
    Abstract Gold nanoprobes immobilized with fluorescein-hyaluronic acid (HA) conjugates are fabricated and utilized for monitoring intracellular reactive oxygen species (ROS) generation in live cells via nanoparticle surface energy transfer. A bio-inspired adhesive molecule, dopamine, is used to robustly end-immobilize HA onto the surface of gold nanoparticles (AuNPs) for securing intracellular stability against glutathione. ROS induces cleavage and fragmentation of the HA chains immobilized on the surface of the AuNPs allows rapid and specific detection of intracellular ROS by emitting strong fluorescence-recovery signals. In particular, fluorescence-quenched gold nanoprobes exhibit selective and dose-dependent fluorescence-recovery signals upon exposure to certain oxygen species such as superoxide anion () and hydroxyl radical (·OH). The fluorescent gold nanoprobe is usefully exploited for real-time intracellular ROS detection and antioxidant screening assay, and has exciting potential for various biomedical applications as a new class of ROS imaging probes. [source]

    Photoinduced Formation of Reactive Oxygen Species from the Acid Form of 6-(Hydroxymethyl)pterin in Aqueous Solution

    HELVETICA CHIMICA ACTA, Issue 6 2006
    Andrés
    Abstract The photochemistry of 6-(hydroxymethyl)pterin (HPT; 1) in aqueous solution (pH 5,6) was investigated by irradiation at 350,nm at room temperature. The photochemical reactions of the acidic form 1a were followed by UV/VIS spectrophotometry, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and enzymatic methods for the determination of the superoxide anion radical (O) and hydrogen peroxide (H2O2). When 1a is exposed to UV-A radiation, the intermediates 4 and 4, are formed reacting with O2 to yield 6-formylpterin (FPT; 5) and 6-carboxypterin (CPT; 6) under formation of O and H2O2 (Scheme,3). The quantum yields of the disappearance of HPT (1a) and of the formation of the photoproducts 5 and 6 were determined. HPT was investigated for its efficiency in singlet-oxygen (1O2) production in acidic aqueous solution. The corresponding quantum yield of 1O2 production (,,) was 0.15,±,0.02, as measured by the 1O2 luminescence in the near-IR (1270,nm) upon continuous excitation of the sensitizer. However, 1O2 does not participate in the actual photooxidation of HPT (1a) to FPT (5) and CPT (6). [source]

    Critical Role of Reactive Oxygen Species and Mitochondrial Permeability Transition in Microcystin-Induced Rapid Apoptosis in Rat Hepatocytes

    HEPATOLOGY, Issue 3 2000
    Wen-Xing Ding
    Microcystin-LR (M-LR) is a specific hepatotoxin. At present, the exact toxic mechanism of its action remains unclear though apoptosis is believed to be involved. This study was designed to investigate the role of reactive oxygen species (ROS) and mitochondrial permeability transition (MPT) in the M-LR,induced apoptotic process. Morphologic changes such as cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and nuclear condensation suggest that M-LR causes rapid apoptosis in hepatocytes. Confocal microscopy revealed that M-LR exposure led to the onset of MPT and mitochondrial depolarization, evidenced by (1) redistribution of calcein fluorescence from cytosol to mitochondria, and (2) loss of mitochondrial tetramethyrhodamine methyl ester (TMRM) fluorescence; both occurred before apoptosis. Moreover, there was a significant and rapid increase of ROS level before the onset of MPT and loss of MMP, indicating a critical role of ROS in M-LR,induced apoptosis. Deferoxamine (DFO), an iron chelator, prevented the increase of ROS production, delayed the onset of MPT, and, subsequently, cell death. In addition, a specific MPT inhibitor, cyclosporin A (CsA), blocked the M-LR,induced ROS formation, onset of MPT, and mitochondrial depolarization as well as cell death. Thus, we conclude that the M-LR,induced ROS formation leads to the onset of MPT and apoptosis. [source]

    Role of topical and nutritional supplement to modify the oxidative stress,

    INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2002
    P. Morganti
    Synopsis Background: Evidence suggests that signs of skin ageing such as wrinkling, ragging and actinic lentigines, may be connected to cumulative oxidative damage incurred throughout our lifetimes. To counteract this oxidative injury, skin is equipped with a network on enzymatic and non-enzymatic antioxidant systems, such as tocopherols, ascorbate polyphenols. All these compounds administered topically by cosmetics or by oral route by diet supplements, have been shown to exert an antioxidant/protective effect in skin or skin cells. Objective: The object of this study was to evaluate both in vitro and in vivo the activity performed by different topical antioxidants and nutritional supplements. Methods: A randomized double-blind placebo-controlled study was carried out for 8 weeks on 30 dry-skinned elderly volunteers, women aged between 48 and 59 years, with moderate xerosis and photoageing. Surface skin lipids, skin hydration and MDA determination were topically detected by 3C System. ROS was evaluated on the blood serum and on IL-3 stimulated human leukocytes by ROS Meter System at 505 nm. All the subjects applied twice a day for 2 months a nanocolloidal gel and/or take a diet supplement by oral route at the quantity of two capsules per day. All the formulations used were antioxidant-enriched (ascorbic acid, tocopherol, alpha-lipoic acid, melatonin, emblica). Results: Oxidative stress and consequently lipids peroxidation decreased from 30 to 40% (P < 0.005) in blood serum of all the subjects treated with antioxidant compounds topically and by oral route. Both free radicals recovered in blood serum and on skin (in vivo) and ROS induced by irradiation of leucocytes with UVB light (in vitro), appear sensibly lower in subjects antioxidant-treated. Conclusions: From the obtained data, it seems possible to conclude that all the compounds used play interesting role as topical and systemic photoprotectants, thanks to their interesting antioxidant property. Moreover, the antioxidant treatment seems to be a promising therapeutic approach also in reducing the oxidative stress of people affected by photoaging. Résumé Les faits semblent montrer que les signes du vieillissement cutané tels que les rides, la perte d'élasticité ou les taches de vieillesse, peuvent être liés aux effets oxydants cumulés subis tout au long de la vie. Pour contrer ces effets oxydants, la peau est équipée d'un réseau de systèmes antioxydants enzymatiques et non enzymatiques tels que les tocophérols, l'ascorbate et les polyphénols. Tous ces composés, administrés par voie topique par des cosmétiques ou par voie orale avec des suppléments alimentaires, se sont révélés exercer un effet antioxydant/protecteur sur la peau ou les cellules de la peau. L'objet de cette étude était d'évaluer aussi bien in-vitro qu'in-vivo l'activité de différents antioxydants topiques et suppléments alimentaires. Une étude randomisée contre placebo en double aveugle a été conduite sur 8 semaines avec 30 volontaires,gés à peau sèche, des femmes de 48 à 59 ans, présentant une xérose et un viellissement modéré. Les lipides à la surface de la peau, l'hydratation de la peau et la MDA ont été suivis de façon topique par le SYSTEM 3 C. Les ROS (Reactive Oxygen Species) ont été déterminés dans le sérum sanguin et sur les leucocytes humains 12-3 stimulés par un SYSTEM ROS-METER à 505 nm. Tous les sujets ont appliqué deux fois par jour pendant deux mois un gel nanocolloïdal et/ou pris des suppléments alimentaires par voie orale à raison de deux gélules par jour. Toutes les formulations utilisées étaient enrichies en antioxydant (acide ascorbique, tocophérol, acide alpha-lipoïque, mélatonine, emblica). Le stress oxydant et par conséquent la péroxydation des lipides diminue de 30 à 40% (p < 0.005) dans le sérum sanguin de tous les sujets traités avec des composés antioxydants par voie topique ou orale. Les radicaux libres retrouvés aussi bien dans le sérum sanguin que dans la peau (in-vivo) et la ROS induite par l'irradiation des leucocytes avec la lumière ultraviolette (in-vitro) apparaissent significativement moins élevés chez les sujets traités aux antioxydants par voie topique ou orale. D'après les données obtenues il semble possible de conclure que tous les composés utilisés jouent un rôle intéressant comme photoprotecteurs topiques et systémiques grâce à leurs intéressantes propriétés antioxydantes. De plus, le traitement antioxydant semble être une approche thérapeutique prometteuse en ce qu'elle réduit aussi le stress oxydant des personnes touchées par le vieillissement. [source]

    Reactive Oxygen Species as Mediators of Cellular Senescence

    IUBMB LIFE, Issue 4-5 2005
    Renata Colavitti
    Abstract Aging has often been viewed as a random process arising from the accumulation of both genetic and epigenetic changes. Increasingly, the notion that aging is a stochastic process is being supplanted by the concept that maximum lifespan of an organism is tightly regulated. This knowledge has led to a growing overlap between classical signal transduction paradigms and the biology of aging. We review certain specific examples where these seemingly disparate disciplines intersect. In particular, we review the concept that intracellular reactive oxygen species function as signalling molecules and that oxidants play a central role as mediators of cellular senescence. IUBMB Life, 57: 277-281, 2005 [source]

    Reactive Oxygen Species and Signal Transduction

    IUBMB LIFE, Issue 1 2001
    Toren Finkel
    Abstract Increasing evidence suggests a role for intracellular reactive oxygen species (ROS) as mediators of normal and pathological signal transduction pathways. In particular, a growing list of recent reports have demonstrated a rapid and significant increases in intracellular ROS following growth factor or cytokine stimulation. These ROS appear essential for a host of downstream signaling events. Biochemical characterization of this ligand-activated ROS production has revealed important information regarding the molecular composition of the cellular oxidases and the regulation of their activity by small GTPases. Work is proceeding on identifying strategies to identify how ROS might specifically regulate signaling pathways by altering the activity of direct target molecules. This review will focus on the progress in the rapid emerging area of oxidant or redox-dependent signal transduction and speculate how these insights might alter our view and treatment of diseases thought to be caused by oxidative stress. [source]

    Cell Compartmentalization in Redox Signaling

    IUBMB LIFE, Issue 1 2001
    Giovambattista Pani
    Abstract From a growing body of evidence on the role of Reactive Oxygen Species as intracellular signaling molecules, the concept starts to emerge that cell responses to redox changes are function of the intracellular site where oxidants are produced and/or meet their molecular targets. In particular,a major distinction between oxidative events in the cytosolic versus the mitochondrial compartment appears to exist in terms of physiological stimuli, signaling mechanisms and functional consequences. Experimental data supporting this view are reviewed here, and the potential implications of this new perspective in redox signaling are discussed. [source]

    Chemistry and Reactions of Reactive Oxygen Species in Foods

    JOURNAL OF FOOD SCIENCE, Issue 9 2005
    Eunok Choe
    ABSTRACT: Reactive oxygen species (ROS) is formed enzymatically, chemically, photochemically, and by irradiation of food. It is also formed by the decomposition and the inter-reactions of ROS. The hydroxy radical is the most reactive ROS and then followed by singlet oxygen. Reactions of ROS with food components produce undesirable volatile compounds and carcinogens, destroy essential nutrients, and change the functionalities of proteins, lipids, and carbohydrates. Lipid oxidation by ROS produces low-molecular-weight volatile aldehydes, alcohols, and hydrocarbons. ROS causes crosslink or cleavage of proteins. ROS produces low-molecular-weight carbonyl compounds from carbohydrates. Vitamins are easily oxidized by ROS, especially singlet oxygen. The singlet oxygen reaction rate was the highest in ,-carotene followed by tocopherol, riboflavin, vitamin D, and ascorbic acid. [source]

    Effects of Fusaric Acid on Reactive Oxygen Species and Antioxidants in Tomato Cell Cultures

    JOURNAL OF PHYTOPATHOLOGY, Issue 10 2001
    E. Ku
    Generation of O2, and H2O2 as well as the activities of superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, dehydroascorbate reductase and ascorbate content were studied in tomato cell cultures in response to fusaric acid , a nonspecific toxin of phytopathogenic Fusarium species. Toxin treatment resulted in decreased cell viability which was preceded by culture medium alkalinization up to 0.65 pH unit and enhanced extracellular O2, production. The H2O2 level was not significantly affected. In toxin-treated cultures, a transient, significant increase occurred in intracellular superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase activities. Fusaric acid-induced ascorbate turnover modulation led to up to a twofold increase in dehydroascorbic acid accumulation, and a decrease in the associated ascorbate redox ratio. It was concomitant with a significant decrease in dehydroascorbate reductase activity. These results support previous observations that the pro- and anti-oxidant systems are involved in response to fusaric acid treatment although differential response of H2O2 and its metabolism-related enzymes between the whole leaf and cell culture assays was found. [source]

    Reactive Oxygen Species Are Necessary for High Flow (Shear Stress)-induced Diameter Enlargement of Rat Resistance Arteries

    MICROCIRCULATION, Issue 5 2009
    ERIC J. BELIN DE CHANTEMÈLE
    ABSTRACT Objectives: Chronic increases in blood flow induce remodeling associated with increases in diameter and endothelium-mediated dilation. Remodeling requires cell growth and migration, which may involve reactive oxygen species (ROS). Nevertheless, the role of ROS in flow-mediated remodeling in resistance arteries is not known. Materials and Methods: Rat mesenteric resistance arteries (MRAs) were exposed to high flow (HF) by sequentially ligating second-order MRAs in vivo. After three weeks, arteries were collected for structural, pharmacological, and biochemical analysis. Results: In HF arteries, luminal diameter (431±12 to 553±14 ,m; n=10), endothelium (acetylcholine)-mediated vasodilatation (61±6 to 77±6% relaxation) and NAD(P)H subunit (gp91phox and p67phox) expression levels, and ROS (dihydroethydine microphotography) and peroxynitrite (3-nitro-tyrosine) production were higher than in normal flow arteries. Acute ROS scavenging with tempol improved acetylcholine-dependent relaxation (92±4% relaxation), confirming that ROS are produced in HF arteries. Chronic treatment with tempol prevented the increase in diameter, reduced ROS and peroxynitrite production, and improved endothelium-mediated relaxation in HF arteries. Thus, ROS and NO were involved in HF-induced diameter enlargement, possibly through the formation of peroxynitrite, while ROS reduced the increase in endothelium-dependent relaxation. Conclusions: ROS production is necessary for flow-mediated diameter enlargement of resistance arteries. However, ROS counteract, in part, the associated improvement in endothelium-mediated relaxation. [source]

    Involvement of Reactive Oxygen Species in TGF-,1-induced Tropoelastin Expression by Human Dermal Fibroblasts

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009
    Won Seon Choi
    Chronic exposure to solar UV radiation causes marked changes in the dermal extracellular matrix that underlie the loss of resiliency and increased laxity observed in photoaged skin. In particular, the dermal elastin content increases substantially and the normal, well-organized elastic fibers are replaced by amorphous elastotic material. Transforming growth factor-,1 (TGF-,1) stimulates synthesis of elastin by dermal fibroblasts and may mediate the increase in elastin in chronically photodamaged skin. We investigated pathways involved in the TGF,,1-induced increase in tropoelastin (TE), the soluble elastin monomer and assessed the role of reactive oxygen species (ROS) in the regulation of TE mRNA. Antioxidants and an inhibitor of NADPH oxidase blocked TGF,,1-induced TE mRNA increase even when added 1.5 h after TGF-,1, although ROS were detected for only 30 min. The TE mRNA increase required activation of Smad4, shown using Smad4 siRNA, and also involved the ERK1/2, p38 and JNK MAP kinases but not PI3K. ROS did not enhance signaling through Smad2 but did enhance activation of p38 and ERK1/2 at 10 min after TGF-,1. These results indicate that Smad and MAPK pathways mediate TGF,,1-induced TE expression and that ROS are required for both early signal transduction and later steps that increase elastin. [source]

    Production of Reactive Oxygen Species on Photolysis of Dilute Aqueous Quinone Solutions

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007
    Shikha Garg
    ABSTRACT We have examined the generation of the reactive oxygen species (ROS) superoxide and hydrogen peroxide (H2O2) by irradiation of dilute aqueous solutions of disodium anthraquinone-2-6-disulfonate (AQDS) with simulated sunlight. Irradiating a solution of AQDS in 2 mM NaHCO3 and 0.01 M NaCl produced superoxide and H2O2 at nanomolar concentrations. Experiments in which initial concentrations of dioxygen, H2O2, the superoxide radical trap nitroblue tetrazolium and the electron donor dimethyl sulfoxide were varied suggested that the interaction of solvent water with photo-excited quinone moieties produces dioxygen-reducing radicals, and that these are the primary source of ROS in the system. A kinetic model for ROS production is proposed based on our experimental data. [source]

    Effect of N-acetyl-L-cysteine Supplementation in Semen Extenders on Semen Quality and Reactive Oxygen Species of Chilled Canine Spermatozoa

    REPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2010
    AJ Michael
    Contents The objective of this study was to evaluate the quality of chilled dog semen processed with extenders containing various concentrations of N-acetyl-L-cysteine (NAC). Ejaculates from five dogs were collected, pooled and evaluated for concentration, motility, rapid steady forward movement (RSF-movement), viability, acrosomal integrity and by the hypo-osmotic swelling test (HOST). In addition, superoxide anion (O2 -,) production, hydroxyl radicals (OH,) and total reactive oxygen species (tROS) were determined. The pool was divided into five aliquots, which were diluted to a final concentration of 66.66 × 106 spermatozoa/ml with Tris-glucose-egg yolk extender containing one of the following concentrations of NAC (0, 0.5, 1, 2.5 or 5 mm). The semen aliquots were chilled and preserved at 4°C. Semen quality was evaluated after rewarming at 72 h. Sperm motility was significantly higher with the 0.5 mm concentration compared with the control group (p = 0.001). Rapid steady forward movement was higher with the 0.5 and 1 mm concentrations compared with the control and 5 mm group (p < 0.001). Viability and HOST percentages were not significantly altered. Compared with the control, the 5 mm concentration showed significantly reduced percentages of spermatozoa with normal acrosomes (p = 0.049). None of the ROS values at 72 h were significantly affected by the presence of NAC in semen extenders, although all NAC concentrations showed lower O2 -, and OH, values compared with the control. Only the concentrations of 1 and 5 mm inhibited the significant increase of tROS values after 72 h, compared with the fresh semen value. In conclusion, NAC supplementation of semen extenders is beneficial to semen motility of canine spermatozoa during chilling with the 0.5 mm concentration being the most effective, although no significant ROS inhibition was observed at 72 h. [source]

    Alcohol Induces Reactive Oxygen Species and Migration in Keratinocytes

    THE LARYNGOSCOPE, Issue S3 2010
    Alex W. Helkin BA
    No abstract is available for this article. [source]

    Determination of Reactive Oxygen Species in Myringotomized Tympanic Membranes: Effect of Vitamin E Treatment

    THE LARYNGOSCOPE, Issue 4 2004
    Senol Polat MD
    Abstract Objectives/Hypothesis Recent studies have established a strong relationship between the development of myringosclerosis and reactive oxygen species (ROS). The aims of the present study were to directly detect ROS in the tympanic membrane and middle ear mucosa of rats by measuring luminol amplified chemiluminescence, to evaluate the changes in the levels of ROS after treatment with vitamin E, and to examine the possible changes in the tympanic membranes otomicroscopically and histologically. Study Design Prospective controlled animal study. Methods Forty healthy Sprague-Dawley rats were divided into five groups of eight animals each. Animals in all groups except group 1 were bilaterally myringotomized. Group 2 received no treatment, group 3 was treated with topical olive oil, group 4 received topical vitamin E, and group 5 received intramuscular vitamin E. After 24 hours of myringotomy, tympanic membranes were examined otomicroscopically; thereafter, tympanic membranes and middle ear mucosa were peeled off. The right ears of the animals were used for biochemical assay, and the left ears were used for histological study. Results Reactive oxygen species levels were significantly decreased in group 4 with topical application of vitamin E compared with untreated and myringotomized animals in group 2. Reactive oxygen species levels were also decreased in group 5, although the decrease was not statistically significant when compared with groups 2 and 3. Histological studies confirmed sclerotic changes in the untreated myringotomized animals. The tympanic membranes of animals in groups 2 and 3 showed a white, chalk-like pattern of sclerotic changes, whereas animals in groups 4 and 5, with the exception of two animals in group 5, lacked these changes. Conclusion Although the relationship between the development of myringosclerosis and ROS had been well documented previously, the present study is the first that has directly measured the levels of ROS in the tympanic membrane and middle ear mucosa. These results are relevant because they correlate with histological findings. It has also been demonstrated that topically applied vitamin E is effective in decreasing the ROS levels. [source]

    Expression of Inducible and Endothelial Nitric Oxide Synthases, Formation of Peroxynitrite and Reactive Oxygen Species in Human Chronic Renal Transplant Failure

    AMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2002
    Ester W. J. A. Albrecht
    Nitric oxide (NO·) is produced by NO synthases (NOS) and can interact with reactive oxygen species (ROS) to form peroxynitrite, which induces protein damage by formation of nitrotyrosine. NO· has a promotional effect on acute rejection. To investigate the role of NO· during chronic renal transplant failure (CRTF), we studied the expression of eNOS and iNOS in conjunction with H2O2 production and the formation of nitrotyrosines. Nephrectomy material from 10 patients and 10 control kidneys was used in this study. Expression of iNOS, eNOS, nitrotyrosine and the presence of ROS-producing cells and macrophages were determined using immunohistochemistry. INOS expression in nonsclerosed glomeruli and interstitium was significantly increased in patients with CRTF (p <,0.05). Glomerular eNOS expression was decreased in patients with CRTF compared with glomeruli of control kidneys (p <,0.01). Nitrotyrosine and ROS positive cells were significantly increased in CRTF in the interstitium (p <,0.05), but not in glomeruli. In summary, we found a marked interstitial increase in iNOS protein expression together with a decrease in glomerular eNOS expression in CRTF patients, associated with a significant increment in ROS and nitrotyrosine-positive cells in the interstitium. Our results suggest that loss of NO· production by glomerular eNOS in conjunction with an increased NO· production by interstitial iNOS, together with the formation of ROS and nitrotyrosine, is involved in the pathogenesis of CRTF. [source]

    Generation of Reactive Oxygen Species and Induction of Apoptosis of HL60 Cells by Ingredients of Traditional Herbal Medicine, Sho-saiko-to

    BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2006
    Toshiko Makino
    Among the components of Sho-saiko-to, wogon, the extract of Scutellaria and licorice root extract induced apoptosis of HL60 cells and increased the intracellular levels of reactive oxygen species. Lower concentrations (5 to 20 ,M) of baicalein, the principal flavonoid in the Scutellaria root extract, showed induction of cell apoptosis and elevated the intracellular reactive oxygen species. However, the increase in the concentrations of baicalein rather inhibited the induction of apoptosis and the elevated levels of reactive oxygen species in cells. Induction of baicalein-mediated apoptosis was inhibited by addition of Tempol, the scavenger of reactive oxygen species. Glycyrrhetinic acid, an ingredient of licorice root extract, also induced apoptosis followed by increase in the intracellular reactive oxygen species. The effect of Sho-saiko-to on cell differentiation can be explained by the action of two ingredients, baicalein and glycyrrhetinic acid, which cause apoptosis and increase in reactive oxygen species in cells. [source]

    ChemInform Abstract: Novel Anthraquinone Derivatives: Synthesis via Click Chemistry Approach and Their Induction of Apoptosis in BGC Gastric Cancer Cells via Reactive Oxygen Species(ROS)-Dependent Mitochondrial Pathway.

    CHEMINFORM, Issue 17 2009
    Shaoru Wang
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Inhibitory Effect Of Reactive Oxygen Species On Angiotensin I-Converting Enzyme (Kininase II)

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2001
    B Michel
    SUMMARY 1. Somatic angiotensin I-converting enzyme (ACE) is a protein that contains two similar domains (N- and C-terminal), each possessing an active site. We have examined the effects of a generator of hydroxyl radicals (g,OH: 2,2,-azo-bis(2-amidinopropane)) and hydrogen peroxide (H2O2) on ACE using an in vitro approach. 2. The generator of hydroxyl radicals inactivated ACE in a time (2,6 h)- and concentration (0.3,3 mmol/L)-dependent manner at 37°C. When ACE was coincubated for 4 h with g,OH (3 mmol/L), its activity decreased by 70%. Addition of dimethylthiourea or mannitol + methionine, two ,OH scavengers, resulted in a significant protection of ACE activity. Mercaptoethanol and dithiotreitol, two thiol-reducing agents, also efficiently protected ACE activity. 3. The hydrolysis of two natural and domain-specific substrates was explored. The hydrolysis of angiotensin I, preferentially cleaved by the C-domain, was significantly inhibited (57,58%) after 4 h exposure to g,OH (0.3,1 mmol/L). Under the same conditions of exposure, the hydrolysis of N -acetyl-Ser-Asp-Lys-Pro, a specific substrate for the N-domain, was only slightly inhibited by 1 mmol/L g,OH. 4. Hydrogen peroxide, another source of ,OH, was used. After exposure to H2O2 (3 mmol/L; 4 h), an 89% decrease in ACE activity was observed. Pretreatment with the iron chelator deferoxamine (1 mmol/L) attenuated H2O2 -mediated ACE inactivation, demonstrating that the effect of H2O2 was partly due to its conversion into ,OH (Fenton reaction). 5. In summary, our findings demonstrate that g,OH and H2O2 inhibit ACE activity and suggest a preferential action of g,OH on the C-domain of the enzyme. [source]

    Reactive Oxygen Species, Aging, and Antioxidative Nutraceuticals

    COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2004
    J. Lee
    ABSTRACT The important roles of reactive oxygen species in diseases related to aging and the necessity and benefits of antioxidative nutraceuticals in the prevention of diseases and promotion of healthy aging have been extensively reported in recent years. Oxygen is an essential component of living organisms. The generation of reactive oxygen species such as superoxide anion, hydrogen peroxide, hydroxyl radicals, and singlet oxygen is inevitable in aerobic metabolism of the body. Reactive oxygen species cause lipid oxidation, protein oxidation, DNA strand break and base modification, and modulation of gene expression. In the past several years, unprecedented progress has been made in the recognition and understanding of roles of reactive oxygen species in many diseases. These include atherosclerosis, vasospasms, cancers, trauma, stroke, asthma, hyperoxia, arthritis, heart attack, age pigments, dermatitis, cataractogenesis, retinal damage, hepatitis, liver injury, and periodontis, which are age-related. The body protects itself from the potential damages of reactive oxygen species. Its first line of defense is superoxide dismutases, glutathione peroxidases, and catalase. Scientists have indicated that antioxidant nutraceuticals supplied from daily diets quench the reactive oxygen species or are required as cofactors for antioxidant enzymes. Nutraceuticals play significant roles in the prevention of a number of age-related diseases and are essential for healthy aging. Epidemiological studies also reported the relevance of antioxidative nutraceuticals to health issues and the prevention of age-related diseases. Health-conscious consumers have made antioxidative nutraceuticals the leading trend in the food industry worldwide in recent years. [source]

    Ongoing activation of p53 pathway responses is a long-term consequence of radiation exposure in vivo and associates with altered macrophage activities,

    THE JOURNAL OF PATHOLOGY, Issue 5 2008
    PJ Coates
    Abstract The major adverse consequences of radiation exposure, including the initiation of leukaemia and other malignancies, are generally attributed to effects in the cell nucleus at the time of irradiation. However, genomic damage as a longer term consequence of radiation exposure has more recently been demonstrated due to untargeted radiation effects including delayed chromosomal instability and bystander effects. These processes, mainly studied in vitro, are characterized by un-irradiated cells demonstrating effects as though they themselves had been irradiated and have been associated with altered oxidative processes. To investigate the potential for these untargeted effects of radiation to produce delayed damaging events in vivo, we studied a well-characterized model of radiation-induced acute myeloid leukaemia in CBA/Ca mice. Haemopoietic tissues of irradiated CBA/Ca mice exhibit enhanced levels of p53 stabilization, increased levels of p21waf1, and increased amounts of apoptosis, as expected, in the first few hours post-irradiation, but also at much later times: weeks and months after the initial exposure. Because these responses are seen in cells that were not themselves directly irradiated but are the descendants of irradiated cells, the data are consistent with an initial radiation exposure leading to persistently increased levels of ongoing DNA damage, analogous to radiation-induced chromosomal instability. To investigate the potential source of ongoing oxidative processes, we show increased levels of 3-nitrotyrosine, a marker of damaging nitrogen/oxygen species in macrophages. Not all animals show increased oxidative activity or p53 responses as long-term consequences of irradiation, but increased levels of p53, p21, and apoptosis are directly correlated with increased 3-nitrotyrosine in individual mice post-irradiation. The data implicate persistent activation of inflammatory-type responses in irradiated tissues as a contributory bystander mechanism for causing delayed DNA damage. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source]

    Diabetic embryopathy: Studies using a rat embryo culture system and an animal model

    CONGENITAL ANOMALIES, Issue 3 2005
    Shoichi Akazawa
    ABSTRACT The mechanism of diabetic embryopathy was investigated using in vitro experiments in a rat embryo culture system and in streptozotocin-induced diabetic pregnant rats. The energy metabolism in embryos during early organogenesis was characterized by a high rate of glucose utilization and lactic acid production (anaerobic glycolysis). Embryos uninterruptedly underwent glycolysis. When embryos were cultured with hypoglycemic serum, such embryos showed malformations in association with a significant reduction in glycolysis. In a diabetic environment, hyperglycemia caused an increased glucose flux into embryonic cells without a down-regulation of GLUT1 and an increased metabolic overload on mitochondria, leading to an increased formation of reactive oxygen species (ROS). Activation of the hexamine pathway, subsequently occurring with increased protein carbonylation and increased lipid peroxidation, also contributed to the increased generation of ROS. Hyperglycemia also caused a myo-inositol deficiency with a competitive inhibition of ambient glucose, which might have been associated with a diminished phosphoinositide signal transduction. In the presence of low activity of the mitochondrial oxidative glucose metabolism, the ROS scavenging system in the embryo was not sufficiently developed. Diabetes further weakened the antioxidant system, especially, the enzyme for GSH synthesis, ,-GCS, thereby reducing the GSH concentration. GSH depletion also disturbed prostaglandin biosynthesis. An increased formation of ROS in a diminished GSH-dependent antioxidant system may, therefore, play an important role in the development of embryonic malformations in diabetes. [source]

    Reactive oxygen and nitrogen species in normal physiological processes

    ACTA PHYSIOLOGICA, Issue 1 2010
    J. Pourova
    Abstract Reactive oxygen species (ROS) and reactive nitrogen species have generally been considered as being highly reactive and cytotoxic molecules. Besides their noxious effects, ROS participate in physiological processes in a carefully regulated manner. By way of example, microbicidal ROS are produced in professional phagocytes, ROS function as short-lived messengers having a role in signal transduction and, among other processes, participate in the synthesis of the iodothyronine hormones, reproduction, apoptosis and necrosis. Because of their ability to mediate a crosstalk between key molecules, their role might be dual (at least in some cases). The levels of ROS increase from a certain age, being associated with various diseases typical of senescence. The aim of this review is to summarize the recent findings on the physiological role of ROS. Other issues addressed are an increase in ROS levels during ageing, and the possibility of the physiological nature of this process. [source]

    Reactive oxygen species in rostral ventrolateral medulla modulate cardiac sympathetic afferent reflex in rats

    ACTA PHYSIOLOGICA, Issue 4 2009
    M.-K. Zhong
    Abstract Aim:, The aim of the present study was to investigate whether reactive oxygen species (ROS) in rostral ventrolateral medulla (RVLM) modulate cardiac sympathetic afferent reflex (CSAR) and the enhanced CSAR response caused by microinjection of angiotensin II (Ang II) into the paraventricular nucleus (PVN). Methods:, Under urethane and ,-chloralose anaesthesia, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in sinoaortic-denervated and cervical-vagotomized rats. The CSAR was evaluated by the RSNA response to epicardial application of capsaicin (1.0 nmol). Results:, Bilateral RVLM microinjection of tempol (a superoxide anion scavenger) or polyethylene glycol-superoxide dismutase (PEG-SOD, an analogue of endogenous superoxide dismutase) attenuated the CSAR, but did not cause significant change in baseline RSNA and MAP. NAD(P)H oxidase inhibitors apocynin or phenylarsine oxide (PAO) also showed similar effects, but SOD inhibitor diethyldithio-carbamic acid (DETC) enhanced the CSAR and baseline RSNA, and increased the baseline MAP. Bilateral PVN microinjection of Ang II (0.3 nmol) enhanced the CSAR and increased RSNA and MAP, which was inhibited by the pre-treatment with RVLM administration of tempol, PEG-SOD, apocynin or PAO. The pre-treatment with DETC in the RVLM only showed a tendency in potentiating the CSAR response of Ang II in the PVN, but significantly potentiated the RSNA and MAP responses of Ang II. Conclusion:, These results suggest that the NAD(P)H oxidase-derived ROS in the RVLM modulate the CSAR. The ROS in the RVLM is necessary for the enhanced CSAR response caused by Ang II in the PVN. [source]

    Assessing cytotoxicity of (iron oxide-based) nanoparticles: an overview of different methods exemplified with cationic magnetoliposomes

    CONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2009
    Stefaan J. H. Soenen
    Abstract Iron oxide nanoparticles are the most widely used T2/T2* contrast agents and for biomedical research purposes, one of the main applications is the in vitro labeling of stem or therapeutic cells, allowing them to be subsequently tracked in vivo upon transplantation. To allow this, the nanoparticles used should not show any sign of cytotoxicity and not affect cellular physiology as this could impede normal cell functionality in vivo or lead to undesired side-effects. Assessing the biocompatibility of the nanoparticles has proven to be quite a difficult task. In the present work, a small overview of commonly used assays is presented in order to assess several aspects, such as cell viability, induction of reactive oxygen species, nanoparticle uptake, cellular morphology, cellular proliferation, actin cytoskeleton architecture and differentiation of stem cells. The main focus is on comparing the advantages and disadvantages of the different assays, highlighting several common problems and presenting possible solutions to these problems as well as pointing out the high importance of the relationship between intracellular nanoparticle concentration and cytotoxicity. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Oxygen-dependent ion transport in erythrocytes

    ACTA PHYSIOLOGICA, Issue 3 2009
    A. Bogdanova
    Abstract The present contribution reviews current knowledge of apparently oxygen-dependent ion transport in erythrocytes and presents modern hypotheses on their regulatory mechanisms and physiological roles. In addition to molecular oxygen as such, reactive oxygen species, nitric oxide, carbon monoxide, regional variations of cellular ATP and hydrogen sulphide may play a role in the regulation of transport, provided that they are affected by oxygen tension. It appears that the transporter molecules themselves do not have direct oxygen sensors. Thus, the oxygen level must be sensed elsewhere, and the effect transduced to the transporter. The possible pathways involved in the regulation of transport, including haemoglobin as a sensor, and phosphorylation/dephosphorylation reactions both in the transporter and its upstream effectors, are discussed. [source]