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PubMed1987

Allopurinol and oxypurinol are hydroxyl radical scavengers.

Allopurinol is a scavenger of the highly reactive hydroxyl radical (k2 approx. 10(9) M-1 X s-1). One product of attack of hydroxyl radical upon allopurinol is oxypurinol, which is a major metabolite of allopurinol. Oxypurinol is a better hydroxyl radical scavenger than is allopurinol (k2 approx. 4 X 10(9) M-1 X s-1) and it also reacts with the myeloperoxidase-derived oxidant hypochlorous acid. Hence the protective actions of allopurinol against reperfusion damage after hypoxia need not be entirely due to xanthine oxidase inhibition.

Allopurinol↗
PubMed1994

TNF-alpha effect on oxygen free radical scavenging and generating enzymes in rat liver.

The presence of cancer induces metabolic alterations in distant, tumor-free tissues and organs of the host. A remote humoral effect of cancer growing extrahepatically is an increase in the activity of oxidant and a decrease of antioxidant enzymes in the liver of the tumor-bearing animal. We speculated that TNF-alpha, produced by host cells, the cancer, or both, is responsible for these changes. When human recombinant TNF-alpha, 100 micrograms/kg/d i.p. for 5 days, was injected in groups of rats fed ad libitum, starved, or pair-fed, a decrease in the activity of superoxide dismutase and glutathione peroxidase and an increase in xanthine oxidase was observed, particularly with pair-fed controls. It is concluded that TNF-alpha, directly or indirectly, causes these enzyme alterations in the tumor-free liver of a tumor-bearing host.

Analysis of Variance↗
PubMed1992

Electron paramagnetic resonance studies on cytochrome b-558 and peroxidases of pig blood granulocytes.

Low-temperature electron paramagnetic resonance (EPR) spectrometry on granulocytes prepared from pig blood was carried out with concentrated cellular and subcellular fractions to characterize EPR signals of cytochrome b-558 (cyt b-558). A thick cell suspension (approximately 2 x 10(9) cells/ml), containing mostly neutrophils, showed typical high-spin EPR signals due to myeloperoxidase (MPO) and a low spin signal at a g value of around 3.2. A similar thick granulocyte suspension containing eosinophils showed not only these signals but also low spin heme signals at g values of 2.86, 2.13, and 1.66, which have been reported to be of cyt b-558 (Ueno et al. 1991, FEBS Lett. 281, 130-132). MPO and eosinophil peroxidase (EPO) were released from the membrane fractions with 50 mM phosphate buffer (pH 7.0) containing 1 M NaCl, and then were highly concentrated, in which no cyt b-558 was detected by absorption spectra. The signal at a g value of 2.86 was found only in the EPO fraction, suggesting that this signal is derived from a low-spin form of an EPO-complex, but neither from MPO nor cyt b-558. The O2(-)-forming NADPH oxidase associated in the membranes was solubilized with heptyl-thio-glucoside at 0 degree C and concentrated up to 45 microM cyt b-558 with no modification of the heme moiety confirmed by its O2(-)-generating activity and lack of carbon monoxide-binding capacity. Cyt b-558 showed an anisotropic signal at a g value of 3.2 +/- 0.05, which was cyanide-insensitive and reducible with reductants. The signal intensity was concentration dependent, suggesting that the g = 3.2 signal is characteristic of the low-spin heme iron in cyt b-558.

Animals↗
PubMed1991

The effect of copper deficiency on adriamycin toxicity.

The effect of copper (Cu) deficiency on antioxidant status of liver and heart and its effect on adriamycin toxicity was assessed. Weanling rats were fed Cu-adequate (+Cu) and Cu-deficient (-Cu) diets for 3 weeks and then injected intraperitoneally once with saline or adriamycin (8 mg/kg). All -Cu rats had increased heart/body weight ratios compared to +Cu rats. Regardless of Cu status, adriamycin decreased body weight and increased heart cytochrome c oxidase, but had no effect on Cu,Zn-superoxide dismutase, glutathione peroxidase, the thiobarbituric acid (TBA) index or liver cytochrome c oxidase activity. -Cu, adriamycin rats had significantly decreased heart weights (0.54 + 0.02 g/kg body wt.) compared to -Cu, saline rats (0.69 +/- 0.05 g/kg body wt.). Four of 6 -Cu rats given adriamycin had abnormal EKGs, with 3 showing extrasystoles and 1 having a severe bradycardia. All +Cu rats given adriamycin had normal EKGs. Pathological changes detected with electron microscopy were most severe in -Cu rats given adriamycin.

Animals↗
PubMed1993

Role of lipid peroxidation in gastric mucosal lesions induced by ischemia-reperfusion in the pylorus-ligated rat.

The peroxidation of lipids and changes in the activities of related enzymes, such as xanthine-xanthine oxidase (XOD), superoxide dismutase (SOD), and glutathione peroxidase (GSH-px) in the gastric mucosa were studied in rat model of ischemia-reperfusion with pylorus ligation. Myeloperoxidase (MPO), a marker enzyme of leucocytes, was also studied. Thiobarbituric acid reactive substances (TBA RS) in gastric mucosa were significantly increased by clamping the celiac artery for 30 min and reperfusion for 60 min after 3 h of pylorus ligation. XOD activity in gastric mucosa increased with the development of gastric mucosal injury. Allopurinol significantly suppressed XOD activity but did not inhibit mucosal injury or the increase in TBA RS. MPO activity in the gastric mucosa was significantly increased by gastric mucosal injury. Famotidine significantly inhibited the increase in MPO activity in gastric mucosa, while allopurinol did not. SOD and GSH-px activities in the gastric mucosa were decreased significantly by gastric mucosal injury. SOD activity was normal following treatment with famotidine and allopurinol. Moreover, GSH-px activity recovered to the normal level with famotidine and allopurinol treatment. These findings suggest that oxygen radicals and lipid peroxidation can cause gastric mucosal injury by ischemia-reperfusion in the pylorus-ligated rat. The generation of oxygen free radicals may be derived mainly from activated polymorphonuclear leukocytes (PMN), and the decrease in SOD and GSH-px activity in gastric mucosa seems to aggravate mucosal injury by free radicals and lipid peroxidation.

Allopurinol↗
PubMed1985

Diffusion of extracellular hydrogen peroxide into intracellular compartments of human neutrophils. Studies utilizing the inactivation of myeloperoxidase by hydrogen peroxide and azide.

It is well known that catalase is transformed to nitric oxide-Fe2+-catalase by hydrogen peroxide (H2O2) plus azide. In this report, we show that myeloperoxidase is also inactivated by H2O2 plus azide. Utilizing this system, we studied the presence and source of intracellular H2O2 generated by activated neutrophils. Stimulation of neutrophils with phorbol myristate acetate (PMA, 100 ng/ml) plus azide (5 mM) for 30 min completely inactivated intragranular myeloperoxidase and reduced cytosolic catalase to 35% of resting cells. This intracellular inactivation of heme enzymes did not occur in normal neutrophils incubated with either PMA or azide alone or in neutrophils from patients with chronic granulomatous disease (CDG) which cannot produce H2O2 in response to PMA. Incubation of neutrophils with azide and a H2O2 generating system (glucose-glucose oxidase) inactivated 41% of neutrophil myeloperoxidase. Glutathione-glutathione peroxidase (GSH-GSH peroxidase), an extracellular H2O2 scavenger, totally protected neutrophil myeloperoxidase from inactivation by azide plus glucose-glucose oxidase. In addition, when a mixture of normal and CGD cells was stimulated with PMA in the presence of azide, 90% of the myeloperoxidase in CGD neutrophils was inactivated. Therefore, H2O2 released extracellularly from activated neutrophils can diffuse into cells. In contrast, myeloperoxidase in normal polymorphonuclear leukocytes stimulated with PMA in the presence of azide and GSH-GSH peroxidase was 75% inactivated. Thus, the results indicate that a GSH-GSH peroxidase-insensitive pool of H2O2 is also generated, presumably at the plasma membrane, and this pool of H2O2 can undergo direct internal diffusion to inactivate myeloperoxidase.

Animals↗
PubMed1989

Test-strip method for measuring lactate in whole blood.

We have developed a dry reagent strip system for measuring lactate in whole blood. The test strip contains lactate oxidase (no EC number assigned), horseradish peroxidase (EC 1.11.1.7), and N-ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine. The system is designed to measure with a reflectometer the color that developed in the test strip, although the lactate concentration can be estimated without the reflectometer. The between-run coefficients of variation for controls at three concentrations were 2.9-5.3%. The lactate concentrations in blood samples from healthy subjects before and after exercise correlated well (r = 0.97) with the results measured by the comparison method with the use of lactate oxidase. This dry reagent strip system provides a convenient and rapid test for measuring blood lactate in clinical and sports medicine.

Horseradish Peroxidase↗
PubMed1976

Cytochemical localization of peroxidase activity in the mitochondria of Hymenolepis diminuta.

A cytochemical study of mitochondria of Hymenolepis diminuta indicates the presence of a mitochondrial peroxidase. Utilizing a 3,3'-diaminobenzidine (DAB) medium at pH 9.7, the reaction product is localized in the intracristal space, and between the inner and outer membranes of the mitochondria. No inhibitory effects are exerted on the peroxidase reaction by cyanide, azide, or aminotriazole. In addition, the mitochondria appear to have an enzyme which is cytochemically similar to vertebrate cytochrome c-oxidase. The possible physiological significance of the peroxidase is discussed.

Animals↗
PubMed2007

Effect of oestrogen on reactive oxygen species production in the aortas of ovariectomized Dahl salt-sensitive rats.

OBJECTIVE: In the present study, we examined whether ovariectomy increases reactive oxygen species (ROS) and the expression of nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase and modulates the scavenger enzymes for ROS in the aortas of Dahl salt-sensitive (DSS) rats fed a high salt diet. METHODS: DSS female rats were ovariectomized and fed a high salt diet (8% NaCl), or a high salt diet plus oestrogen supplement for 4 weeks. Urinary levels of hydrogen peroxide (H2O2) were measured by using 2',7'-dichlorofluorescein. The expression of an NADPH oxidase subunit p22phox, extracellular superoxide dismutase (ecSOD), glutathione peroxidase (GPx)1, GPx4 and monocyte chemoattractant protein 1 (MCP-1) messenger RNA was assessed by reverse transcription-polymerase chain reaction. The expression of MCP-1, and macrophage infiltration were examined by immunohistochemical analysis. RESULTS: Ovariectomy increased superoxide production and the expression of NADPH oxidase subunit p22phox mRNA and protein in the aortas of DSS rats fed a high salt diet. In contrast, ovariectomy reduced the expression of ecSOD mRNA and protein and the expression of GPx1 and GPx4 mRNA in the aorta. Ovariectomy increased MCP-1 mRNA and protein expression and ED1-positive cells in the aorta. CONCLUSIONS: Ovariectomy leads to an amplification of oxidative stress in DSS rats fed a high salt diet synergistically by an increase in the ROS-generating system and a decrease in the ROS-eliminating system, as shown in the increase in superoxide production and the urinary excretion of H2O2. Oestrogen supplementation counteracted these alterations, showing how oestrogen is antioxidative.

Animals↗
PubMed2004

Lead exposure raises superoxide and hydrogen peroxide in human endothelial and vascular smooth muscle cells.

BACKGROUND: Chronic lead exposure causes hypertension and cardiovascular disease, which are associated with, and, in part, due to oxidative stress. While occurrence of oxidative stress in lead-exposed animals and cultured endothelial cells has been well-established, direct and specific evidence on the type of the reactive oxygen species (ROS) produced by lead-exposed vascular cells is lacking and was investigated. METHODS: Human coronary endothelial (EC) and vascular smooth muscle cells (VSMC) were incubated in appropriate culture media in the presence of either 1 ppm or 10 ppm lead acetate or sodium acetate (control) for 1 to 30 minutes or 60 hours. Productions of superoxide and hydrogen peroxide in the cell populations were determined by flow cytometry using hydroethidine and dihydrorhodamine, respectively. Data from a minimum of 10,000 cells were collected and analyzed using Cell Quest software. In addition, Cu Zn superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX), and NAD(P)H oxidase (gp91phox) were measured. RESULTS: Short-term lead exposure resulted in a significant rise in both superoxide and hydrogen peroxide production by both EC and VSMC. After long-term exposure, detectable superoxide levels fell to near normal level, while hydrogen peroxide production remained high. This was associated with up-regulations of gp91phox, elevation of superoxide dismutase, reduction of VSMC catalase, and no change in GPX levels. Together, these events can account for the observed decline in superoxide and the rise in hydrogen peroxide following long-term lead exposure. CONCLUSION: Lead exposure promotes generation of superoxide and hydrogen peroxide in human EC and VSMC. This phenomenon can potentially contribute to the pathogenesis of the lead-associated hypertension and cardiovascular disease, and points to the potential benefit of lowering lead burden in the exposed populations.

Catalase↗
PubMed2006

Caffeic acid phenethyl ester suppresses oxidative stress in Escherichia coli-induced pyelonephritis in rats.

Although oxidative damage is known to be involved in inflammatory-mediated tissue destruction, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory diseases. Caffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives, has antioxidant, anti-inflammatory and antibacterial properties. For that reason, we aimed to investigate the efficiency of CAPE administration in preventing oxidative damage in pyelonephritis (PYN) caused by Escherichia coli. In this study, 35 Wistar rats were grouped as follows: control, PYN 24 h, PYN 48 h, PYN 72 h, CAPE 24 h, CAPE 48 h and CAPE 72 h. E. coli (1 x 10(9) c.f.u.) were inoculated into the rats in both PYN and CAPE groups via urethral catheterization. Ten microM/kg-body weight CAPE was injected to the rats in all CAPE groups 24 h before E. coli infection, and injections were repeated at 24-h intervals. Rats were sacrificed 24 h, 48 h and 72 h after infection in both PYN and CAPE groups. Malondialdehyde (MDA) and nitric oxide (NO) levels were significantly increased in kidneys of PYN groups. The activities of the antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and xanthine oxidase (XO) were also elevated by E. coli. However, CAPE administration reduced MDA and NO levels, as well as XO activity, although it increased SOD and GSH-Px activities. Histopathological examination showed that CAPE reduced the inflammation grade induced by E. coli. In conclusion, CAPE administrations decrease the oxidative damage occurring in PYN and therefore could be used for medical management of bacterial nephropathy.

Animals↗