Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Superoxides”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

Increased superoxide generation is associated with decreased superoxide dismutase activity and mRNA expression in placental trophoblast cells in pre-eclampsia.

Pre-eclampsia is a multi-system disorder unique to human pregnancy. Although the aetiology of pre-eclampsia is still unknown, increased placental oxidative stress contributes to the pathophysiology of this pregnancy disorder. The goal of this study was to determine if placental trophoblast cells generate superoxide, and if there was a difference in superoxide generation and superoxide dismutase (SOD) activity between trophoblast cells isolated from pre-eclamptic placentae versus normal placentae. Placentae were obtained from nine normal and 10 pre-eclamptic pregnancies immediately after delivery. Trophoblast cells were isolated and purified by Percoll density gradient centrifugation. Superoxide generation and SOD activity were determined by spectrophotometric assays. Localization of CuZn-SOD protein within the placenta was examined by immunohistochemical staining. mRNA expression of CuZn-SOD was determined in trophoblast cells isolated from five normal and five pre-eclamptic pregnancies by Northern blot analysis. 18S ribosomal mRNA expression was used as an internal standard. We found: (1) trophoblast cells from pre-eclamptic placentae generated significantly more superoxide than trophoblast cells from normal placentae: 17.62+/-3.19 versus 4.70+/-0.76 nmol/5x10(6) cells (mean+/-s.e.), P< 0.01; (2) protein and mRNA expression for CuZn-SOD was mainly localized in the trophoblast cells within the placenta; and (3) SOD activity and relative mRNA expression for CuZn-SOD were significantly decreased in trophoblast cells from pre-eclamptic placentae as compared to trophoblast cells from normal placentae, SOD activity: 6.46+/-1.76 versus 13.01+/-1.67 units/mg protein, P< 0.05; relative mRNA expression for CuZn-SOD: 0.25+/-0.09 versus 0.73+/-0.07, P< 0.01. We conclude that increased superoxide generation was associated with decreased SOD activity and mRNA expression for CuZn-SOD in trophoblast cells isolated from pre-eclamptic placentae. These findings support the notion of increased oxidative stress in the pre-eclamptic placenta, which may contribute to the pathophysiology of this pregnancy disorder.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed1989

Role of superoxide dismutase in the pathogenesis of pyelonephritis: immunological localization of superoxide dismutase in human renal tissues.

The enzyme superoxide dismutase affords a protective effect from renal scarring secondary to acute pyelonephritis in primates. To investigate the relationship between renal superoxide dismutase content and age we selected formalin-fixed normal human renal tissue from subjects of varying age, ranging from premature infant to adult, for immunostaining with human anti-superoxide dismutase antibody using the peroxidase-antiperoxidase technique. Sections that demonstrated acute pyelonephritis were immunostained for comparison. Immunostaining for superoxide dismutase was detected consistently in the proximal tubular cell cytoplasm in all specimens regardless of subject age. Superoxide dismutase was not detected in other segments of the nephron. In kidneys that demonstrated acute pyelonephritis we detected enhanced immunostaining in the proximal tubules, as well as increased background staining related to the inflammatory cells present. These results in conjunction with recent demonstrations of proximal tubular cell endocytosis of bacteria suggest that superoxide dismutase has an important role in mediating the initial events of pyelonephritis within the proximal tubular cell.

Adult↗
PubMed1979

Superoxide production in pulmonary alveolar macrophages and killing of BCG by the superoxide-generating system with or without catalase.

The superoxide production of BCG-infected and noninfected alveolar macrophages was measured by superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The cells were incubated with or without cell-free bronchial lavage fluid (pulmonary washings). When control alveolar macrophages were infected by BCG, superoxide production was decreased markedly, probably due to bacterial cytotoxic factors. In contrast, the production of superoxide in alveolar macrophages exposed to pulmonary washings was increased and not appreciably influenced by BCG infection. Superoxide production by alveolar macrophages was dependent on time and on the protein concentration in the pulmonary washings. In controls, it was inversely proportional to the infecting dose of BCG. We observed previously that alveolar macrophages activated by pulmonary washings inhibited intracellular growth of BCG. We now present evidence that enhanced production of superoxide contributes to such inhibition, especially in the presence of catalase at acid pH. These findings are pertinent to the defense of inflamed lungs, where serum and serum immunoglobulin G transuded from blood into alveolar spaces probably induce such activation on alveolar macrophages.

Animals↗
PubMed1991

Polyethylene glycol-conjugated superoxide dismutase fails to augment brain superoxide dismutase activity in piglets.

We studied the effect of intravenously administered polyethylene glycol-conjugated superoxide dismutase (8,000 units/kg) on brain superoxide dismutase activity in 44 1-2-week-old piglets in the absence and presence of global cerebral ischemia and reperfusion. Four groups (n = 6 each) of piglets not exposed to ischemia were studied. Enzyme administration increased plasma superoxide dismutase activity from less than 5 to 142 +/- 8 units/ml (mean +/- SEM) without increasing brain activity (e.g., activities in the caudate were 7.9 +/- 0.5 and 8.1 +/- 0.4 units/mg protein) for up to 2 hours following administration. Four additional groups (n = 5 each) of piglets were given either enzyme or polyethylene glycol 5 minutes prior to 10 minutes of global cerebral ischemia induced by aortic cross-clamping followed by either 5 or 45 minutes of reperfusion. Enzyme administration increased plasma superoxide dismutase activity from less than 5 to 144 +/- 5 units/ml but failed to increase brain activity even after 45 minutes of reperfusion (e.g., activities in the caudate were 8.5 +/- 0.3 and 8.6 +/- 0.6 units/mg protein). We conclude that intravenous polyethylene glycol-conjugated superoxide dismutase does not increase superoxide dismutase activity in the brain despite global ischemia and reperfusion.

Animals↗
PubMed1992

Osteoclastic superoxide generation: taking control of bone resorption using modulators of superoxide concentrations.

We have examined the role of superoxide in bone resorption by stimulating defective superoxide production and bone resorption in patients with osteopetrosis and inhibiting superoxide production and bone resorption in murine calvarial explants. Interferon gamma treatment did stimulate superoxide generation and bone resorption in patients with osteopetrosis as evidenced by a reduction in bone volume and an increase in biochemical markers of bone resorption. Further, lowering the superoxide concentrations within calvarial osteoclasts using a scavenger, desferal manganese, decreased bone resorption. We conclude that superoxide generation by osteoclasts is necessary for normal osteoclastic function.

Animals↗
PubMedDate not supplied

Spontaneous lipid peroxidation and production of hydrogen peroxide and superoxide in human spermatozoa. Superoxide dismutase as major enzyme protectant against oxygen toxicity.

Spontaneous lipid peroxidation in washed human spermatozoa was induced by aerobic incubation at 32 C and measured by malonaldehyde production; loss of motility during the incubation was determined simultaneously. Malonaldehyde production at the point of complete loss of motility, defined as the lipoperoxidative lethal endpoint (LLE), was 0.10 +/- 0.03 nmol/10(8) cells (mean +/- SD, n = 40), and was independent of the time to complete loss of motility. Human spermatozoa produced both H2O2 and O2-. during aerobic incubation. Inhibition of superoxide dismutase in these cells with KCN showed that all the H2O2 production is due to action of the dismutase. The superoxide dismutase activity of individual human sperm samples varied between 1 and 10 U/10(8) cells, variations between samples from a single donor being nearly as great as those between different donors. The time to complete motility loss (tL) showed equal variation of 1 to 10 hours among samples. The rate of spontaneous lipid peroxidation, calculated as LLE/tL, for a given sperm sample and the superoxide dismutase activity of the same sample, determined prior to aerobic incubation, gave a good linear correlation (r = 0.97). Glutathione reductase, glutathione peroxidase, and glutathione were found to be present in human spermatozoa, but showed little variation among samples. These results suggest that superoxide dismutase plays the major role in protecting human spermatozoa against lipid peroxidation. In addition, the superoxide dismutase activity of a fresh sperm sample appears to be a good predictor of the lifetime (up to the complete loss of motility) of that particular sample, and so may prove useful in semen analysis.

Humans↗
PubMed1998

Detection of superoxide radicals and peroxynitrite by 1-hydroxy-4-phosphonooxy-2,2,6,6-tetramethylpiperidine: quantification of extracellular superoxide radicals formation.

The reactions of the new sterically hindered hydroxylamine 1-hydroxy-4-phosphonooxy-2,2,6,6-tetramethylpiperidine (PP-H) with superoxide radical and peroxynitrite have been studied. These reactions produce the nitroxide 4-phosphonooxy-2,2,6, 6-tetramethyl-piperidinyloxy. The rate constant for reaction of superoxide with PP-H is determined as (8.4+/-0.6).10(2) M-1s-1. It was found that PP-H provides almost the same spin trapping efficacy as 1-hydroxy-3-carboxy-pyrrolidine (CP-H). The background oxidation of PP-H in blood is much less than for CP-H. The extremely slow PP-H penetration into the cells makes possible the study of extracellular formation of superoxide radical. The acute treatment of blood with nitroglycerin is shown to induce an extracellular superoxide radical formation. PP-H is more sensitive for detection of reactive oxygen species as compared with CP-H. PP-H is an effective scavenger of superoxide radical and of peroxynitrite, and can be used to quantify the extracellular formation of these reactive oxygen species.

Electron Spin Resonance Spectroscopy↗
PubMed1980

Oxygen utilization by Lactobacillus plantarum. II. Superoxide and superoxide dismutation.

Cell-free extracts of Lactobacillus plantarum contain non-proteinaceous compounds which mimic superoxide dismutase activity. Using the test system in which O-2 is generated by xanthine oxidase, superoxide dismutase activity is found in cell-free extracts, where proteins are removed by precipitation. This activity is strongly decreased after dialysis of cell-free extracts. Superoxide dismutase activity was also investigated by means of pulse radiolysis. Cell-free extracts of Escherichia coli were also investigated as a comparison, which were known to contain superoxide dismutase. With cell-free extracts of both L. plantarum and E. coli the decay of O-2 was markedly increased. However, the type of reaction of the O-2 decay was of first order in the presence of E. coli extracts due to superoxide dismutase(s), and of second order in the presence of L. plantarum extracts, indicating that O-2 elimination is not an enzymic reaction. Mn2+ phosphate(s) might be responsible for the observed elimination of O-2. The production of O-2 is not detectable during NADH-, lactate- or pyruvate oxidase reactions in L. plantarum extracts.

Cell-Free System↗
PubMed1979

Effects of superoxide radicals on transport (Na + K) adenosine triphosphatase and protection by superoxide dismutase.

Membrane (Na +K)ATPase isolated from rat brain was preincubated in a medium in which superoxide radicals were generated enzymatically. Exposure to superoxide radicals caused an irreversible inactivation, which could be prevented by further addition of superoxide dismutase. (Na + K)ATPase was also protected by addition of allopurinol, a xanthine oxidase inhibitor, during preincubation. The K-activated nitrophenylphosphatase associated with (Na + K)ATPase was also found to be inactivated by preincubation with superoxide radicals, which could be prevented by superoxide dismutase.

Allopurinol↗
PubMed1983

Superoxide dismutase assay using alkaline dimethylsulfoxide as superoxide anion-generating system.

Alkaline dimethylsulfoxide as a superoxide anion-generating system in association with cytochrome c as a superoxide anion-indicating scavenger has been used to develop a new assay for superoxide dismutase. The assay is sensitive (one unit of enzymatic activity is provided by 110 ng of purified copper-containing superoxide dismutase) and highly specific. The nature of this system prevents the usual interferences and its simplicity allows for multiple, rapid measurements of superoxide dismutase activity in biological preparations using either normal or automated procedures.

Autoanalysis↗
PubMed2006

TEMPOL, a membrane-permeable radical scavenger, attenuates peroxynitrite- and superoxide anion-enhanced carrageenan-induced paw edema and hyperalgesia: a key role for superoxide anion.

Carrageenan produces both inflammation and pain when injected in rat paws via enhancement of the formation of reactive oxygen species. We have tested the effect of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL), a membrane-permeable superoxide dismutase (SOD) mimetic in carrageenan-induced rat paw edema. Treatment of rats with TEMPOL (15, 30, and 60 mg/kg, 15 min prior to carrageenan) inhibited the paw edema. Furthermore, treatment of rats with the SOD inhibitor diethylthiocarbamate (DETCA, 100 mg/kg, 1 h before carrageenan) enhanced the carrageenan-induced paw edema. Co-administration of peroxynitrite with carrageenan produced a similar fortification of the carrageenan-induced edema. Prior treatment of rats with TEMPOL (30 mg/kg) inhibited the enhancement produced by DETCA treatment (endogenous superoxide anion stress) as well as that produced by the peroxynitrite stress. The effect of TEMPOL as well as the influence of superoxide anion and peroxynitrite stresses was also tested in carrageenan-induced hyperalgesia model. Carrageenan (500 mug/paw) produced significant hyperalgesia presented as shortening of withdrawal latency times using hot plate (52 degrees C) starting 30 min after carrageenan and lasting for 3 h. TEMPOL (60 mg/kg, injected 15 min before carrageenan) ameliorated this hyperalgesia during the first 2 h. Concurrent administration of peroxynitrite promptly intensified the carrageenan hyperalgesia. TEMPOL (60 mg/kg, 15 min before peroxynitrite-carrageenan) inhibited the peroxynitrite enhancement of carrageenan hyperalgesia when tested at 60 min after injection of the cocktail. The present investigation gives the proof for the effectiveness of TEMPOL as anti-inflammation and analgesic agents in carrageenan-induced model of inflammation and hyperalgesia. It further indicated the importance of superoxide anion and peroxynitrite in acute inflammation and inflammatory pain. This raises the chances for considering pharmacologic interventions that interrupt superoxide anion and peroxynitrite stress for putative alternative agents as anti-inflammatory analgesic new medical strategies.

Animals↗
PubMed1997

Augmented inhibitory effect of superoxide dismutase on superoxide anion release from macrophages by direct cationization.

Superoxide dismutase (SOD) was modified into cationized form (Cat-SOD) in order to enhance its pharmacological efficacy based on an electrostatic interaction. The inhibitory effect of Cat-SOD on superoxide anion release from inflammatory macrophages and its cellular interaction were studied in vitro. Cat-SOD exhibited an excellent inhibitory effect on superoxide anion release from the macrophages, and this effect surpassed those of native SOD and SOD modified with mannose (Man-SOD) which is taken up via mannose receptor-mediated endocytosis by macrophages. In the presence of colchicine, a microtubule-disruptive agent, the inhibitory effect of Cat-SOD was slightly impaired, whereas the effect of Man-SOD completely disappeared. The intracellular localization of fluorescein isothiocyanate-labeled SOD, Cat-SOD and Man-SOD observed by confocal laser microscopy supported the difference in their abilities to eliminate superoxide anions. The different sensitivities of Cat-SOD and Man-SOD to colchicine were also confirmed by the confocal laser microscopic images, suggesting their distinct intracellular trafficking pathways in the macrophages. In conclusion, Cat-SOD is desirable for its pharmacological activity, which is probably the result of its ability to be delivered to the vicinity of NADPH-oxidase which locates in the cell membrane and generates superoxide anions.

Animals↗
PubMed2000

Superoxide release and superoxide dismutase expression by human gingival fibroblasts.

Oxygen reactive intermediates released from phagocytic cells are important for microbicidal activity, but they may also be harmful to surrounding cells and matrix components at the inflammation site. In different forms of inflammatory periodontal disease, peripheral and crevicular polymorphonuclear leukocytes, as well as mononuclear phagocytes and gingival fibroblasts, are exposed to bacterial cell wall components and cytokines. The aim of this study was to evaluate if some bacterial components and cytokines induce superoxide release and superoxide dismutase (SOD) expression in gingival fibroblasts. Lipopolysaccharide (LPS), streptococcal cell walls (SCW), and formyl-methionyl-leucyl-phenylalanine were found to stimulate O2- release from gingival fibroblasts, which increased when Ca2+ was added. Phorbol myristate acetate, a potent activator of respiratory burst in phagocytes, was found to be a weak stimulator of O2- release in gingival fibroblasts. Of the cytokines tested, tumor necrosis factor (TNF)-alpha was found to activate superoxide release in gingival fibroblasts. Gene expression for manganese superoxide dismutase (MnSOD), but not for copper/zinc superoxide dismutase (CuZnSOD), was demonstrated in fibroblasts exposed to LPS, SCW and TNF-alpha using Northern blot analysis. The production of MnSOD may be protective for these cells. We conclude that bacterial cell wall components and cytokines modulate O2- release by gingival fibroblasts which may contribute to periodontal pathology.

Analysis of Variance↗
PubMed1996

Superoxide-mediated clastogenesis and anticlastogenic effects of exogenous superoxide dismutase.

Superoxide-mediated clastogenesis is characteristic for various chronic inflammatory diseases with autoimmune reactions and probably plays a role in radiation-induced clastogenesis and in the congenital breakage syndromes. It is consistently prevented by exogenous superoxide dismutase (SOD), but not by heat-inactivated SOD, indicating that the anticlastogenic effect is related to the catalytic function of the enzyme. Increased superoxide production by activated monocytes/macrophages is followed by release of more long-lived metabolites, so-called clastogenic factors, which contain lipid peroxidation products, unusual nucleotides of inosine, and cytokines such as tumor necrosis factor alpha. Since these components are not only clastogenic, but can stimulate further superoxide production by monocytes and neutrophils, the genotoxic effects are self-sustaining. It is shown here that anticlastogenic effects of exogenous SOD are preserved despite extensive washing of the cells and removal of all extracellular SOD. Using flow cytometry and confocal laser microscopy, rapid adherence of the fluorescently labeled enzyme to the cell surface could be observed with slow uptake into the cell during the following hours. The degree of labeling was concentration and time dependent. It was most important for monocytes, compared with lymphocytes, neutrophils, and fibroblasts. The cytochrome c assay showed significantly diminished O2- production by monocytes, pretreated with SOD and washed thereafter. The preferential and rapid binding of SOD to monocytes may be of importance not only for the superoxide-mediated genotoxic effects, described above, but also from a therapeutic standpoint. It can explain the observation that beneficial effects of injected SOD lasted for weeks and months despite rapid clearance of the enzyme from the blood stream according to pharmacodynamic studies.

Animals↗
PubMed1992

Rickettsia rickettsii induces superoxide radical and superoxide dismutase in human endothelial cells.

Human endothelial cells infected with Rickettsia rickettsii, the etiological agent of Rocky Mountain spotted fever, undergo striking morphological changes to the endoplasmic reticulum-outer nuclear envelope complex. These changes are accompanied by concurrent accumulation of intracellular peroxides. Both of these findings are consistent with the notion that cells undergo some form of oxidative stress. Since oxidant injury is often initiated or mediated through oxygen radicals, we examined superoxide radical generation when endothelial cells were exposed to R. rickettsii. We also examined the levels of superoxide dismutase, an enzyme induced in response to increased superoxide formation. The levels of both superoxide and superoxide dismutase increased when endothelial cells were exposed to R. rickettsii. These results, together with our previous findings, support our hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury that may eventually contribute to cell death.

Cells, Cultured↗
PubMed2002

Gene transfer of endothelial NO synthase and manganese superoxide dismutase on arterial vascular cell adhesion molecule-1 expression and superoxide production in deoxycorticosterone acetate-salt hypertension.

Enhanced vascular cell adhesion molecule-1 (VCAM-1) expression directly contributes to vascular dysfunction in hypertension. Decreased NO and/or increased superoxide are causative factors for such an event in the vessel wall. The present study was undertaken to determine whether gene transfer of endothelial NO synthase (eNOS) or manganese superoxide dismutase (MnSOD) affects VCAM-1 levels in arteries from hypertensive rats. Isolated carotid and femoral arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats were transduced for 4 hours with adenoviral vectors encoding eNOS, MnSOD, or beta-galactosidase reporter genes. Recombinant eNOS or MnSOD expression was evident morphologically and quantitatively 24 hours after gene transfer. Immunohistochemistry, ELISA, and Western blot techniques were used to determine VCAM-1 expression and levels. In addition, endogenous eNOS and MnSOD and in situ superoxide levels were analyzed by immunoblotting and fluorescence confocal microscopy, respectively. Arterial VCAM-1 expression was significantly higher in DOCA-salt hypertensive rats than in sham-operated rats; this expression was accompanied by decreased MnSOD but unaltered endogenous eNOS levels. VCAM-1 expression was significantly lower in MnSOD- and eNOS-transduced hypertensive arteries, with a concomitant reduction of superoxide level. These results suggest that gene transfer of MnSOD or eNOS suppresses arterial VCAM-1 expression in DOCA-salt hypertension by reducing the superoxide level.

Animals↗
PubMed1996

Mitochondrial complex I deficiency leads to increased production of superoxide radicals and induction of superoxide dismutase.

Mitochondria were isolated from skin fibroblast cultures derived from healthy individuals (controls) and from a group patients with complex I (NADH-CoQ reductase) deficiency of the mitochondrial respiratory chain. The complex I deficient patients included those with fatal infantile lactic acidosis (FILA), cardiomyopathy with cataracts (CC), hepatopathy with tubulopathy (HT), Leigh's disease (LD), cataracts and developmental delay (CD), and lactic acidemia in the neonatal period followed by mild symptoms (MS). Production of superoxide radicals, on addition of NADH, were measured using the luminometric probe lucigenin with isolated fibroblast mitochondrial membranes. Superoxide production rates were highest with CD and decreased in the order CD >> MS > LD > control > HT > FILA = CC. The quantity of Mn-superoxide dismutase (MnSOD), as measured by ELISA techniques, however, was highest in CC and FILA and lowest in CD. Plots of MnSOD quantity versus superoxide production showed an inverse relationship for most conditions with complex I deficiency. We hypothesize that oxygen radical production is increased when complex I activity is compromised. However, the observed superoxide production rates are modulated by the variant induction of MnSOD which decreases the rates, sometimes below those seen in control fibroblast mitochondria. In turn, we show that the variant induction of MnSOD is most likely a function of the change in the redox state of the cell experienced rather than a result of the complex I defect per se.

Cardiomyopathies↗
PubMed1995

Decreased superoxide dismutase activity and increased superoxide anion production in cardiac hypertrophy of spontaneously hypertensive rats.

In order to investigate SHR hypertrophied heart myocardial vulnerability, superoxide dismutase, a potent scavenger of superoxide anion, was examined in myocardium of SHR and WKY in relation to aging, as well as under doxorubicin (DOX)-induced cardiomyopathy. Superoxide anion production due to doxorubicin administration was also examined histochemically. Superoxide dismutase (SOD), either as Mn-SOD in mitochondria or as CuZn-SOD in cytoplasm, was found to be lower in aged SHR hypertrophied heart than in age-matched WKY heart. Under DOX-induced cardiomyopathy, SOD activity was significantly lower in SHR hypertrophied heart than either control SHR or treated WKY myocardium. Superoxide anion generation, examined morphologically as formazan deposits, was much more intense in SHR myocardium and some degenerative changes were found such formazan-containing cells. These results clearly indicate that the myocardial vulnerability of SHR hypertrophied heart might be a result of a lowered free radical scavenge ability.

Aging↗