Oxidative stress in distant organs and the effects of allopurinol during experimental acute pancreatitis.

BACKGROUND: The present study was aimed at an assessment of the role of oxygen-derived free radicals in the development of local and systemic manifestations of L-arginine (Arg)-induced acute pancreatitis and at an evaluation of the protective effect of the xanthine oxidase inhibitor allopurinol. METHODS: Acute pancreatitis was induced in male Wistar rats by injecting 2 x 250 mg/100 g body weight of Arg intraperitoneally at an interval of 1 h, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. In a third group, 200 mg/kg of allopurinol was administered subcutaneously 30 min before the first Arg injection. Rats were killed at 6, 12, 24, or 48 h following Arg administration. Acute pancreatitis was confirmed by a serum amylase level elevation and typical inflammatory features were observed microscopically. Tissue concentrations of malonyl dialdehyde (MDA), superoxide dismutase (Mn- and Cu,Zn-SOD), glutathione peroxidase (GPx), and catalase were measured in the pancreas, liver, and kidney. RESULTS: The tissue concentration of MDA was significantly elevated in each organ. The activities of Mn-SOD, Cu,Zn-SOD, GPx, and catalase were quickly depleted in the pancreas and kidney, whereas only the Mn-SOD and GPx activities were reduced in the liver after the onset of pancreatitis. Histologic examination revealed acinar cell necrosis in the pancreas, but only mild alterations in the liver and kidney. Allopurinol pretreatment prevented the generation of reactive oxygen metabolites in the pancreas and reduced their formation in the kidney. CONCLUSION: Oxygen-derived free radicals are generated in the pancreas, liver, and kidney at an early stage of Arg-induced acute pancreatitis. The liver and the kidney, but not the pancreas, are able to defend against oxidative stress. The prophylactic application of allopurinol significantly restrains the generation of free radicals in pancreas and kidney.     

Involvement of Oxygen-Derived Free Radicals in L-Arginine-Induced Acute Pancreatitis

This study was aimed at an assessment of the role of oxygen-derived free radicals in the pathogenesis of L-arginine (Arg)-induced acute pancreatitis in rat, by measuring the levels of malonyl dialdehyde (MDA), glutathione peroxidase (GPx), catalase, and superoxide dismutase (Mn- and Cu,Zn-SOD) in the pancreatic tissue, and evaluating the protective effect of the xanthine oxidase inhibitor allopurinol. Acute pancreatitis was induced in male Wistar rats by injecting 2 × 250 mg/100 g body weight of Arg intraperitoneally in a 1-hr interval, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. Allopurinol, 100 or 200 mg/kg, was administered subcutaneously 30 min before the first Arg injection. Rats were killed at 6, 12, 24, and 48 hr following Arg administration, and acute pancreatitis was confirmed by a serum amylase level elevation and typical inflammatory features observed microscopically. The serum level of amylase reached the peak level at 24 hr after the Arg injection (30,800 ± 3813 vs 6382 ± 184 units/liter in the control) and normalized at 48 hr. The tissue concentration of MDA was significantly elevated at 24 hr and reached the peak value at 48 hr (5.00 ± 1.75 vs 0.28 ± 0.05 nM/mg protein in the control). The catalase and Mn-SOD activities were significantly decreased throughout the study, while the GPx activity was significantly reduced at 6 and 12 hr, and the Cu,Zn-SOD activity was significantly lower at 12 hr after the Arg injection as compared with the controls. Allopurinol treatment markedly reduced the serum amylase elevation (12.631 ± 2.257 units/liter at 24 hr) and prevented the increase in tissue MDA concentration (0.55 ± 0.09 nM/mg protein at 48 hr). Both doses of allopurinol significantly ameliorated the pancreatic edema, necrosis, and inflammation at 48 hr after Arg administration. Oxygen-derived free radicals are generated at an early stage of Arg-induced acute pancreatitis. Prophylactic allopurinol treatment prevents the generation of reactive oxygen metabolites, reduces the serum amylase concentration, and exerts a beneficial effect on the development of histopathological changes.     

Effects of octreotide on acute necrotizing pancreatitis in rabbits

AIM: To assess the role of oxygen-derived free radicals and cytokines in the pathogenesis of taurocholic acid-induced acute pancreatitis, and to evaluate the preventive effects of octreotide towards the development of acute pancreatitis. METHODS: Acute pancreatitis was induced in male New Zealand white rabbits by retrograde injection of 0.8 mL/kg·b·m, of 50 g/L sodium taurocholate(NaTC) in the pancreatic duct. Sham-operated animals served as control. Octreotide 1 mglkg·b.m.was administered subcutaneously before the induction of pancreatitis. Blood was taken from the jugular vein before and at 1, 3, 6, 12 and 24 h after pancreatitis induction.Serum activities of amylase, IL-6 and TNF-α and levels of malonyl dialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), catalase and superoxide dismutase (Mn-,Cu-,and Zn-SOD) in pancreatic tissue were measured.RESULTS: Serum TNF-α and IL-6 levels increased significantly 3 h after the onset of pancreatitis, and then returned to control level. The tissue concentration of MDA was significantly elevated at 24 h, while the GSH level and GP-x, catalase, Mn-SOD, Cu-, Zn-SOD activities were all significantly decreased in animals with pancreatitis as compared to the control. Octreotide pretreatment significantly reversed the changes in cytokines and reactive oxygen metabolites. Octreotide treatment did not alter the serum amylase activity and did not have any beneficial effects on the development of histopathological changes.CONCLUSION: Oxygen-derived free radicals and proinflammatory cytokines are generated at an early stage of NaTc-induced acute pancreatitis in rabbits. Prophylac ticoctreotide treatment can prevent release of cytokines and generation of reactive oxygen metabolites, but does not have any beneficial effects on the development of necrotizing pancreatitis.     

Increase in liver antioxidant enzyme activities in non-alcoholic fatty liver disease.

AIMS: Steatosis may increase oxidative stress, which is counteracted by cellular enzymatic (cytosolic and mitochondrial superoxide dismutases (Cu/Zn-SOD and Mn-SOD), glutathione peroxidase (GPx), catalase) and non-enzymatic antioxidant systems. We aimed to determine, in patients with non-alcoholic fatty liver disease (NAFLD), the level of antioxidant defenses (1) in liver biopsies, to demonstrate the existence of oxidative stress; (2) in erythrocytes and plasma, to determine whether their antioxidant defenses reflect liver oxidative stress. METHODS: Erythrocyte and plasma antioxidant defenses were prospectively studied in two groups of 16 patients: patients with NAFLD and controls. Liver biopsies were performed in eight NAFLD patients; liver antioxidant enzyme activities were measured and compared with those in 12 control livers used for transplantation. RESULTS: Cu/Zn-SOD, GPx and catalase activities were significantly higher in NAFLD livers than in controls whereas no significant differences were observed in Mn-SOD activity, and thiobarbituric acid-reactive substance (TBARS) concentration. No differences were observed in erythrocyte antioxidant enzyme activities (GPx, catalase, Cu/Zn-SOD), erythrocyte TBARS concentration, and plasma alpha-tocopherol concentration. CONCLUSIONS: Liver antioxidant enzyme activities were high in patients with NAFLD, reflecting an oxidative stress possibly involved in inflammation and fibrogenesis. However, erythrocyte and plasma antioxidant defenses did not reflect intrahepatic peroxidation.     

The role of oxygen free radicals in experimental acute pancreatitis in the rat

In order to elucidate the role of oxygen-derived free radicals in acute pancreatitis, scavengers and an inhibitor of production of these free radicals were administered to rats with experimentally-induced acute pancreatitis. Acute reflux pancreatitis was produced by the occlusion of the common bile duct (OCD). Catalase and superoxide dismutase (SOD) were used as scavengers, and allopurinol was used as an inhibitor of production of free radicals. Six h after surgery, serum amylase, lipase, and thiobarbituric acid (TBA) reactant levels were elevated significantly, and histological changes in the pancreas, consisting of edema, inflammatory cell infiltration, and necrosis, partially around the intralobular and interlobular ducts, developed in the control rats receiving no agent. However, serum lipase and amylase levels in the rats given each agent were significantly lower (p<0.05) than in the controls. The histological changes in the pancreas were less marked in agent-treated rats than in untreated rats. These results suggest that oxygen-derived free radicals participate in the development of acute pancreatitis.     

The role of oxygen free radicals in experimental acute pancreatitis in the rat

In order to elucidate the role of oxygen-derived free radicals in acute pancreatitis, scavengers and an inhibitor of production of these free radicals were administered to rats with experimentally-induced acute pancreatitis. Acute reflux pancreatitis was produced by the occlusion of the common bile duct (OCD). Catalase and superoxide dismutase (SOD) were used as scavengers, and allopurinol was used as an inhibitor of production of free radicals. Six h after surgery, serum amylase, lipase, and thiobarbituric acid (TBA) reactant levels were elevated significantly, and histological changes in the pancreas, consisting of edema, inflammatory cell infiltration, and necrosis, partially around the intralobular and interlobular ducts, developed in the control rats receiving no agent. However, serum lipase and amylase levels in the rats given each agent were significantly lower (p less than 0.05) than in the controls. The histological changes in the pancreas were less marked in agent-treated rats than in untreated rats. These results suggest that oxygen-derived free radicals participate in the development of acute pancreatitis.     

Superoxide dismutases in the human colorectal cancer sequence

 Purpose : The oxidant-antioxidant balance within tissues is thought to contribute to the development and progression of cancer. Previous investigations have indicated changes in this balance during the colorectal oncogenic process that merit further investigation. The aim of the present study was to evaluate whether the human colorectal cancer sequence is accompanied by changes in the protein and activity levels of the antioxidant enzymes manganese- and copper/zinc-superoxide dismutase (Mn-SOD and Cu/Zn-SOD). Patients and methods : SOD levels were assessed in colorectal adenomas, carcinomas, and liver metastases and were compared with those in the corresponding normal tissues (n=35 in each group). Mn- and Cu/Zn-SOD expression was first evaluated semiquantitatively by electrophoretic activity analysis, immunoblotting, and immunohistochemistry and was subsequently quantified by enzyme-linked immunosorbent assays (ELISAs) and spectrophotometric activity assays. Results : The semiquantitative analyses showed enhanced Mn-SOD levels, primarily localized in (neoplastic) epithelial cells, in carcinomas, and in liver metastases as compared with adenomas and normal mucosa, whereas no consistent pattern was observed for Cu/Zn-SOD. Normal liver tissue expressed the highest levels of both SODs. The quantitative SOD analyses confirmed these observations and revealed that carcinomas and liver metastases expressed 2–4 times more Mn-SOD protein and enzymatic activity (0.0005 < P ≤ 0.01) than did the normal mucosa. Adenomas expressed intermediate Mn-SOD levels, which increased significantly with the diameter and tended to increase with the grade of dysplasia and presence of a villous component. In contrast, adenomas, carcinomas, and the corresponding normal mucosa were found to have a similar Cu/Zn-SOD content, whereas liver metastases contained significantly (P < 0.02) more Cu/Zn-SOD as compared with these tissues. In addition, the Cu/Zn-SOD content was not related to any histopathological characteristic of the carcinomas or adenomas. Conclusions : Our study indicates that the development of neoplasia in the human colorectum is accompanied by major changes in the level and activity of Mn-SOD. This observation illustrates that Mn-SOD might have a functional role in human colorectal carcinogenesis. Received: 2 November 1998 / Accepted: 12 January 1999     

Effect of age and hypoxia/reoxygenation on mRNA expression of antioxidative enzymes in rat liver and kidneys

The influence of a short-time isobaric hypoxia as well as reoxygenation on markers of oxidative stress (MDA, total SOD, GSH) and on the mRNA expression of the antioxidative enzymes (Cu/Zn-and Mn-SOD, catalase, GSH reductase and GSH peroxidase) has been studied in liver and kidneys of young (6 months) and old (22–25 months) Wistar rats.

In livers of old animals, the concentration of GSH, the activity of SOD, and the mRNA expression of the antioxidative enzymes (except Mn-SOD) points to a restricted protection against oxidative stress or a lower production of ROS compared to young animals. Hypoxia resulted in a significant decrease of enzyme gene expression in both age groups. Reoxygenation caused an increase in mRNA of Cu/Zn-SOD and GPX in livers of young and of Mn-SOD in livers of old animals.

In kidneys, gene expression of Cu/Zn-SOD, GSH reductase, and GPX was significantly higher in old animals compared to young animals. Whereas hypoxia caused a decrease of gene expression in the livers, it lead to a significant increase of Cu/Zn-SOD, catalase, and GSH reductase mRNA in kidneys of young rats. A reduced gene expression was observed after reoxygenation. In old kidneys, the expression of all enzymes except for catalase progressively declined in the hypoxic and reoxygenation groups. These data show that gene expression of antioxidative enzymes is affected by age and significantly differs between liver and kidney.     

Role of oxygen-derived free radicals in diet-induced hemorrhagic pancreatitis in mice

The role of oxygen-derived free radicals in the pathogenesis of acute pancreatitis was studied by evaluating the effects of catalase, allopurinol, and dimethylsulfoxide on diet-induced acute hemorrhagic pancreatic necrosis in mice. The mortality rate and degree of hyperamylasemia associated with this model of pancreatitis were reduced by catalase but a similar result followed the administration of heat-denatured catalase, suggesting that the apparent protective effect of catalase was not the result of reductions in free radical levels. Neither allopurinol nor dimethylsulfoxide reduced mortality or degree of hyperamylasemia. The increased pancreatic content of amylase and the necrosis that characterize this model of pancreatitis were not altered by any of the agents tested. In contrast, both allopurinol and dimethylsulfoxide reduced peripancreatic edema formation, suggesting that edema, but not the other features that characterize this model of pancreatitis, may result from generation of oxygen-derived free radicals.     

Xanthine oxidase inhibitor in acute experimental pancreatitis in rats and mice

It has been suggested that oxygen-derived free radicals play a decisive role in the pathogenesis of acute experimental pancreatitis in a model of edematous pancreatitis. Accordingly, allopurinol, a xanthine oxidase inhibitor, was shown to mitigate the development of nonfatal acute pancreatitis in ex vivo perfusion models using dogs. For further evaluation of allopurinol, its effect was studied in two forms of fatal necrotizing acute experimental pancreatitis: sodium taurocholate-induced pancreatitis in rats and choline-deficient ethionine-supplemented diet-induced pancreatitis in mice. Allopurinol did not affect the mortality rate, pancreatic enzyme elevation in serum and ascites, the enzyme content of the pancreas, or any parameter indicating histopathological damage in the pancreas. Although these experiments did not determine the role oxygen-derived free radicals play in the development of pancreatitis, they show, none the less, the absence of any beneficial therapeutic effect of a xanthine oxidase like allopurinol on the development of the disease once it has begun.     

Allopurinol attenuates caerulein induced acute pancreatitis in the rat.

Oxygen derived free radicals have been implicated in the pathogenesis of acute pancreatitis in numerous animal models of the disease. The xanthine oxidase inhibitor allopurinol has been shown to attenuate pancreatic damage in canine and mouse models of acute pancreatitis presumably by preventing the generation of cytotoxic superoxide anions. We therefore examined whether allopurinol could attenuate pancreatic injury in conscious rats with caerulein induced acute pancreatitis. A continuous intravenous infusion of allopurinol (20 mg/kg/h) for six hours along with an acute pancreatitis producing dose of caerulein (10 micrograms/kg/h) reduced pancreas weights by approximately 45% and serum amylase concentrations by approximately 60% compared with rats intravenously infused with either caerulein alone or caerulein plus a lower dose (10 mg/kg/h) of allopurinol. We conclude that the generation of oxygen derived free radicals via pancreatic xanthine oxidase represents an early and perhaps pivotal mechanism in the pathogenesis of acute pancreatitis.     

Effect of carnitine on stress-induced lipid peroxidation in rat gastric mucosa

Purpose. Carnitine is an essential cofactor in the mitochondrial transfer of fatty acids, but is also a scavenger of oxygen free radicals in mammalian tissues. It has been shown that cold-restraint stress (CRS) produces gastric mucosal injury due to oxygen free radicals. The aim of this study was to determine the effect of l-carnitine on lipid peroxidation induced by CRS in rat stomachs. Methods. Rats pretreated with l-carnitine (50 mg/kg per day for 10 days) were restrained in a wire cage for 4 h at 4°C. At the end of the experimental period, the lesion index in gastric mucosa was determined. In blood and gastric mucosa samples, the content of mucin, prostaglandin (PG)E₂, the products of lipid peroxidation, and catalase activity were measured. Results. CRS caused a significant decrease in gastric mucin and PGE₂ content, while in the gastric mucosa of rats pretreated with l-carnitine, the changes in gastric mucin and PGE₂ content, as well as gastric lesion development and enhanced lipid peroxide formation due to stress, were prevented. On the other hand, catalase activity in blood increased in the CRS group, while its value in gastric mucosa was not different from that in the control rats. l-Carnitine treatment increased catalase activity in both blood and gastric mucosa in control animals. Following stress, increased catalase activity of blood was associated with decreased mucosal catalase activity in rats that received l-carnitine. Conclusions. l-Carnitine prevents the occurrence of mucosal lesions by strengthening the gastric mucosal barrier and by reducing the products of lipid peroxidation against noxious factors that cause elevation of lipid peroxidation, such as CRS. Received: January 31, 2000 / Accepted: November 10, 2000     

Effects of Tetrandrine and QYT on ICAM-1 and SOD gene expression in pancreas and liver of rats with acute pancreatitis

AIM: Available experimental evidence from both clinical and animal models shows that both Chinese medicines tetrandine (Tet) and Qing Yi Tong (QYT) have positive treatment effects on acute pancreatitis (AP). This investigation was conducted to explore the treatment mechanisms of Tet and QYT on AP at the molecular level and thereby explain their therapeutic affects. It included an investigation of the effects of these drugs on gene expression of both intercellular adhesion molecule 1 (ICAM-1) and superoxide dismutase (Mn-SOD and Cu, Zn-SOD) in a rat model with AP. METHODS: AP in the test rats was induced by subjecting them to laparotomy followed by a retrograde injection of 4 % sodium taurocholate into the bilio-pancreatic duct. The test rats with AP were divided into three groups. One was treated with Tet, one with QYT, and one with normal saline solution. The sham-operated control group (SO) rats were only subjected to laparotomy. They were given no further treatment. For the Tet group, Tet was injected intraperitoneally, and for the QYT group, QYT was given with a nose-gastric catheter. These procedures were done at both 10 min and 5 h after AP induction. The levels of ICAM-1 mRNA expression and of SOD (Mn-SOD and Cu, Zn-SOD) mRNA expression in the pancreas and liver tissues were measured by RT-PCR at 1, 5, and 10 h after AP induction. RESULTS: When compared with the SO group during the observation time, rats with AP showed a higher expression of ICAM and a lower expression of Mn-SOD in both pancreas and liver tissues, and a lower expression of Cu, Zn-SOD in the pancreas. Tet treatment attenuated changes in the expression of both ICAM-1, and SOD (Mn-SOD and Cu, Zn-SOD) to a significant degree. A similar effect on the expression of SOD (Mn-SOD and Cu, Zn-SOD) was also found in the QYT group, but no obvious suppressive effect on ICAM-1 expression was observed. CONCLUSION: The results of this study suggest that one of the main mechanisms of Tet and QYT in treating AP is to enhance anti-oxidation of the body. The results also suggest that the anti-inflammatory effect of Tet is involved in the reduction of ICAM-1 expression. This explains why Tet and QYT are beneficial in treating AP.     

An ultrastructural study to investigate the effect of allopurinol on cerulein-induced damage to pancreatic acinar cells in rat

Summary Conclusion Subcellular organelles and membranes were the structures most protected by allopurinol, indirectly demonstrating their role of main and early target of oxygen-derived free radicals in the pathogenesis of acute pancreatitis. Background The present work evaluates the ultrastructural changes during cerulein-induced acute pancreatitis in rat with and without treatment with allopurinol. Methods and Results Supramaximal doses of cerulein, injected intraperitoneally (50 μg/kg) twice, at 1-h interval, caused severe subcellular alterations, including zymogen distribution, pathological vacuoles, and damage to organelles and membranes. Cotreatment (40 mg/kg ip twice with 1-h interval;n=10 rats) and, most of all, pretreatment (40 mg/kg ip allopurinol, 1 h; 20 mg/kg ip allopurinol+50 μg/kg ip cerulein, 30 min; 40 mg/kg ip allopurinol, 30 min; 50 μg/kg ip cerulein;n=10 rats) with allopurinol showed significant morphological improvement.     

Cu/Zn-SOD in human pancreatic tissue and pancreatic juice

Summary Conclusion Cu/Zn-SOD is present in pancreatic juice and tissue. Immunohistochemical studies reveal a localization of this enzyme in islet, duct, and centroacinar cells, but to a much lower extent in pancreatic acinar cells. Background It is generally accepted that oxygen radicals are involved in the pathogenesis of acute and chronic pancreatitis. An imbalance of radical-generating and radical-scavenging processes is thought to lead to the damage of pancreatic acinar cells that initiate the autodigestion of the whole organ. Methods We investigated the distribution pattern of the cytosolic radical-scavenging enzyme, copper/zinc-superoxide dismutase (Cu/Zn-SOD), in pancreatic juice and tissue. In patients with chronic pancreatitis or pancreatic malignancies, Cu-Zn-SOD was quantitated in different fractions of pancreatic juice by means of an enzyme immunoassay using two Cu/Zn-SOD-specific monoclonal antibodies. Cryostat or paraffin sections of pancreatic tissue were analyzed by immunohistochemical techniques. Results We found this enzyme to be present in the first secretin-triggered fraction of endoscopically obtained pancreatic juice in concentrations similar to serum. In contrast, after cholecystokinin stimulation, only low levels could be found in pancreatic juice, indicating that this enzyme is not actively secreted. Interestingly, pancreatic juice of patients with chronic pancreatitis or pancreas tumor contained higher levels (25–29 ng/mL) of Cu/Zn-SOD than juice of controls without pancreatic diseases (15 ng/mL). Immunohistochemical studies of Cu/Zn-SOD in pancreatic tissue revealed a more intense staining of duct cells, islet cells, and centroacinar cells, whereas acinar cells showed almost no staining for Cu/Zn-SOD.     

Oxidative stress in rodent closed duodenal loop pancreatitis

Summary Conclusions Production of excited oxygen species is earlier in the liver than in the pancreas and could contribute to damage in a reflux model. Treatment with SOD could attenuate 59% light emission in pancreas, but did not modify serum enzyme levels or pancreatic edema, resulting as an insufficient isolated therapy. Unexpectedly, it was found an increased plasma antioxidant capacity that was related to total bilirubin levels, and declined at late stages probably denoting other circulating antioxidant consumption. Background Oxidative stress has been shown to play a role in different models of acute pancreatitis, although it has not been studied in the severe necrohemorrhagic model produced by closed duodenal loop pancreatitis. Methods We studied Sprague Dawley female rats in two groups: a closed duodenal loop pancreatitis group and a control, sham-operated group. In order to evidence the oxygen excited species production,in situ spontaneous chemiluminescence from living and naturally perfused pancreas and liver was measured at 0, 0.5, 1.5, 3, 6, 12, and 24 h after the duodenal ligature. Blood pancreatic amylase and aminotransferases levels were determined as expression of tissue damage in pancreas and liver. At the same time, plasma antioxidant capacity was measured by the peroxyl radical trapping capability of plasma samples compared to that of Trolox (synthetic analog of vitamin E), and results are expressed as Trolox equivalence. Bovine superoxide dismutase (SOD) was administered to attenuate oxygen free radicals activity at the beginning of the peroxidation chain and also as a therapeutic tool. Results The experimental procedure induced a severe pancreatitis, as evidenced by pancreatic enzymes that rose markedly in the early hours of disease and remained heightened throughout the experiment. The results show early light emission from the liver at 3 h and peak levels at 12 h, whereas in the pancreas, luminescence increased at 6 h and doubled later at 12 h, both returning to control levels at 24 h.     

Copper, zinc superoxide dismutase catalyzes hydroxyl radical production from hydrogen peroxide.

Cu,Zn superoxide dismutase (Cu,Zn-SOD; EC 1.15.1.1) is known to be inhibited slowly by H2O2. Using EPR and the spin traps 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) and N-tert-butyl-alpha-phenylnitrone (PBN), we have shown that Cu,Zn-SOD catalyzes the formation of "free" .OH radicals from H2O2 in pH 7.6 bicarbonate buffer. Supporting evidence includes the following: (i) H2O2 and active Cu,Zn-SOD are required to yield significant signals from spin-trap-OH adducts. (ii) With O2-., Cu,Zn-SOD causes the appearance of intense resonance signals due to DMPO-OH adducts. These signals were inhibited strongly by catalase. (iii) With H2O2, Cu,Zn-SOD, and DMPO, radical scavengers formate and azide, but not ethanol, decrease DMPO-OH signals while causing new intense signals due to their corresponding DMPO-radical adducts. Failure of ethanol to quench DMPO-OH signals is discussed in light of the positively charged active channel of the enzyme. (iv) With PBN as a spin trap, ethanol quenches .OH radical signals and yields PBN-trapped hydroxyethyl radical signals. (v) Mn-SOD does not catalyze "free" .OH radical formation and it also exerts no effect on the signals of DMPO-OH adducts when added together with the Cu,Zn-SOD. The capacity of Cu,Zn-SOD to generate "free" .OH radicals from H2O2 may in part explain the biological damage associated with elevated intracellular SOD activity.     

Aerobic training and L-arginine supplement attenuates myocardial infarction-induced kidney and liver injury in rats via reduced oxidative stress

IntroductionThe aim of the present study was to determine the effect of exercise training and l-arginine supplementation on kidney and liver injury in rats with myocardial infarction (MI).Material and methodsFour weeks after MI, 50 male wistar rats randomly divided into five followed groups: sham surgery without MI (Sham, n = 10), Sedentary-MI (Sed-MI, n = 10) 3: L-Arginine-MI (La-MI, n = 10) 4: Exercise training-MI (Ex-MI, n = 10) and 5: Exercise and L-arginine-MI (Ex + La-MI). Ex-MI and Ex + La-MI groups running on a treadmill for 10 weeks with moderate intensity. Rats in the L-arginine-treated groups drank water containing 4% L-arginine. Tissues oxidative stress and kidney and liver functional indices were measured after treatments.ResultUrea as a kidney function indexes, increased in Sed-MI group in compared to sham group and decreased significantly in Ex-MI and Ex + La-MI groups. The level of catalase (CAT) and glutathione stimulating hormone (GSH) of kidney were significantly lower in the MI-groups compared with the Sham group and kidney Malondialdehyde (MDA) levels increased after MI and significantly decreased in response to aerobic training and L-arginine. As well as, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as liver injury indices, increased in MI-groups and decreased by training and L-arginine. In this regards, liver MDA and CAT respectively increased and decreased in MI-groups, but aerobic training and L-arginine increased liver glutathione per-oxidase (GPx) and decreased liver MDA.ConclusionThese results demonstrated that kidney and liver function impaired 14 weeks after MI and aerobic training and L-arginine supplementation synergistically ameliorated kidneys and liver injury in myocardial infarction rats through oxidative stress reduction.     

Free radical scavengers prevent reflux esophagitis in rats

Free radical damage in reflux esophagitis of rats induced by 24-hr duodenojejunal ligation was studied. Oxygen free radicals were selectively blocked. Groups were: sham operation, reflux, reflux+superoxide dismutase (SOD), catalse, dimethylthiourea, allopurinol, and inactivated SOD or inactivated catalase alone or in the combination SOD+catalase or SOD+catalase+dimethylthiourea+allopurinol. Macroscopic esophagitis was inhibited only by SOD, alone or in combination with other agents. Esophageal mucosal lipid peroxidation was 10-fold increased in the reflux group compared to the sham group (P<0.05). This response was damped by SOD>catalase (P<0.05) but not by the inactivated enzymes, dimethylthiourea or allopurinol. SOD+catalase showed no significant improvement on SOD alone. Total inhibition of lipid peroxidation was achieved by combining all scavengers. Total glutathione (GSH) in the esophageal mucosa was stimulated by reflux. This response was inhibited by scavengers equivalent to their efficacy in preventing lipid peroxidation. It is concluded that reflux esophagitis is associated with free radical release with O₂ ^– being the main source. Free radicals appear to stimulate GSH production in this prolonged oxidative stress.Presented at the Digestive Disease Week in New Orleans, May 1994. Published as an abstract inGastroenterology 106:A210, 1994.     

Waist circumference is a major determinant of oxidative stress in subjects with and without metabolic syndrome

AimOxidative stress (OS) plays a major role in pathogenic mechanisms associated with metabolic syndrome (Mets) yet the main component of Mets contributing most to OS is not well elucidated. Hence, the aim of this study was to investigate the oxidative-antioxidative status in Mets subjects and to determine the main predicting component of OS.MethodsAnthropometric measures, fasting blood glucose, lipid profile, antioxidant enzymes [catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx)], reduced glutathione (GSH), malondialdehyde (MDA) and protein carbonyl were assessed in 172 adult UAE residents. International Diabetes Federation criteria were used for Mets diagnosis. Mets Scores (0–5) were calculated and assigned per subject based on number of components.ResultsOf all participants, 22.1% had Mets and 49.4% had large waist circumference (WC). Significant lower levels of catalase, SOD, GPx and GSH, and higher levels of MDA and protein carbonyl were observed in subjects with Mets. In addition, catalase, SOD, GPx, and GSH correlated negatively, while MDA and protein carbonyl correlated positively with almost all Mets components. Similar trend of correlations was noticed with Mets Scores. When adjusted for age and gender, linear regression analysis revealed that subjects with large WC demonstrated significantly lower levels of antioxidative enzymes and GSH, and higher levels of MDA and protein carbonyl. Consequently, WC emerged as the best predictor of OS.ConclusionsThe degree of OS is dependent on the Mets Scores, and WC contributes independently to increased OS among adults in UAE.