HO-1 induction attenuates renal damage and oxidative stress induced by K2Cr2O7

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme HO-1 protects against some types of acute tissue injury. The expression and functional role of HO-1 in rats with renal injury induced by potassium dichromate (K(2)Cr(2)O(7)) was investigated in this work. Rats were studied 24 h after a single injection of K(2)Cr(2)O(7). To address the possible protective effect of HO-1 in this experimental model, this enzyme was induced by an injection of stannous chloride (SnCl(2)) 12 h before K(2)Cr(2)O(7) administration. The functional role of HO-1 in K(2)Cr(2)O(7) + SnCl(2)-treated animals was tested by inhibiting HO activity with an injection of zinc (II) protoporphyrin IX (ZnPP) 18 h before K(2)Cr(2)O(7). In K(2)Cr(2)O(7)-treated rats: (i) renal HO-1 content, measured by Western blot, increased 2.6-fold; and, (ii) renal nitrotyrosine and protein carbonyl content, markers of oxidative stress, increased 3.5- and 1.36-fold, respectively. Renal damage and oxidative stress were ameliorated and HO-1 content was increased in the K(2)Cr(2)O(7) + SnCl(2) group. The attenuation of renal injury and oxidative stress was lost by the inhibition of HO activity in K(2)Cr(2)O(7) + SnCl(2) + ZnPP-treated animals. Our data suggest that HO-1 overexpression induced by SnCl(2) is responsible for the attenuation of renal damage and oxidative stress induced by K(2)Cr(2)O(7).     

Garlic ameliorates gentamicin nephrotoxicity: relation to antioxidant enzymes

Reactive oxygen species are involved in gentamicin (GM) nephrotoxicity, and garlic is effective in preventing or ameliorating oxidative stress. Therefore, the effect of garlic on GM nephrotoxicity was investigated in this work. Four groups of rats were studied: (i) fed normal diet (CT), (ii) treated with GM (GM), (iii) fed 2% garlic diet (GA), and (iv) treated with GM and 2% garlic diet (GM + GA). Rats were placed in metabolic cages and GM nephrotoxicity was induced by injections of GM (75 mg/kg every 12 h) for 6 d. Lipoperoxidation and enzyme determinations were made in renal cortex on day 7. GM nephrotoxicity was made evident on day 7 by (i) tubular histological damage, (ii) enhanced BUN and urinary excretion of N-acetyl-beta-D-glucosaminidase, and (iii) decreased creatinine clearance. These alterations were prevented or ameliorated in GM + GA group. The rise in lipoperoxidation and the decrease in Mn-SOD and glutathione peroxidase (GPx) activities observed in the GM group, were prevented in the GM + GA group. Cu, Zn-SOD activity and Mn-SOD and Cu,Zn-SOD content did not change. CAT activity and content decreased in the GM, GA, and GM + GA groups. CAT mRNA levels decreased in the GM group. The protective effect of garlic is associated with the prevention of the decrease of Mn-SOD and GPx activities and with the rise of lipoperoxidation in renal cortex.     

低氧-复氧胁迫对鲢抗氧化酶活性及Cu/Zn-SOD和Mn-SOD基因表达的影响

为探究低氧-复氧胁迫对鲢(Hypophthalmichthys molitrix)抗氧化酶活性及Cu/Zn-SOD和Mn-SOD基因表达的影响, 对鲢进行急性低氧、持续低氧及复氧实验, 进而分析血清、心脏和肝脏中不同抗氧化酶和SODs基因表达的变化特征。结果表明: 在急性低氧胁迫后, 血清中总抗氧化能力(T-AOC)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)活性随着氧浓度的降低均呈上升趋势, 但超氧化物歧化酶(SOD)活性呈先升后降的趋势。在持续低氧胁迫后, 血清中T-AOC和GSH-PX活性随着低氧胁迫时间的增加显著升高(P<0.05); 心脏中SOD活性显著高于常氧水平(P<0.05), 但Cu/Zn-SOD和Mn-SOD基因表达在低氧胁迫24h时显著低于常氧水平(P<0.05); 肝脏中SOD活性在低氧胁迫24h时显著高于常氧水平(P<0.05), 且Cu/Zn-SOD和Mn-SOD基因表达在低氧胁迫24h时也显著高于常氧水平(P<0.05)。复氧后, 血清、心脏和肝脏中T-AOC、SOD、CAT和GSH-PX活性均能恢复至常氧水平, 且心脏和肝脏中Cu/Zn-SOD和Mn-SOD基因表达的也能恢复至常氧水平, 但肝脏中Mn-SOD基因表达恢复至常氧水平较在心脏中所需时间更少。因而, 鲢可以通过调节抗氧化酶的活性来保护自身免受氧化应激造成的损伤。研究为解析低氧胁迫下鲢抗氧化应激机制提供了基础。     

Effects of Cadmium on Antioxidant Enzyme Activities in Sugar Cane

Sugar cane (Saccharum officinarum L. cv. Copersucar SP80-3280) seedlings were grown in nutrient solution with varying concentrations (0, 2 and 5 mM) of cadmium chloride for 96 h. Leaves were analysed for catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD) activities. Although a clear effect of CdCl₂ on plant growth was observed, the activity of SOD was not altered significantly. However, the CAT activity decreased as the concentration of CdCl₂ increased. GR exhibits a significant increase in activity at 2 and 5 mM CdCl₂. CAT and SOD isoenzymes were further characterised by analysis in non-denaturing PAGE. Activity staining for SOD revealed up to seven isoenzymes in untreated control and 2 mM CdCl₂ treated plants, corresponding to Cu/Zn-SOD isoenzymes. At 5 mM CdCl₂, only six Cu/Zn-SOD isoenzymes were observed. No Fe-SOD and Mn-SOD isoenzymes were detected. For CAT, one band of activity was observed.     

氯化钠胁迫下嫁接黄瓜叶片SOD和CAT mRNA基因表达及其活性

研究了NaCl胁迫下嫁接和自根黄瓜叶片Cu/Zn-SOD、Mn-SOD和CAT mRNA的表达与其酶活性变化及其MDA含量和电解质渗漏率变化.结果表明：在NaCl胁迫条件下,嫁接黄瓜叶片Cu/Zn-SOD mRNA、Mn-SOD mRNA和CAT mRNA的相对表达量均高于自根黄瓜,SOD、Cu/Zn-SOD、Mn-SOD和CAT活性也均高于自根黄瓜,说明与自根黄瓜相比,嫁接黄瓜叶片较高的Cu/Zn-SOD mRNA、Mn-SOD mRNA和CAT mRNA相对表达量是其维持较高Cu/Zn-SOD、Mn-SOD和CAT活性的重要原因;随着NaCl胁迫时间的延长,嫁接和自根黄瓜叶片Cu/Zn-SOD- mRNA、Mn-SOD mRNA和CAT mRNA的相对表达量均呈上升趋势,但其酶活性变化并不完全一致,说明还有其他因素参与相关酶活性的调控;嫁接黄瓜叶片MDA含量和电解质渗漏率均低于自根黄瓜,说明嫁接黄瓜具有较高的活性氧清除系统,可以减少活性氧物质的危害,提高其耐盐性.     

24-Hour variation in gene expression of redox pathway enzymes in rat hypothalamus: effect of melatonin treatment

Abstract

The 24-h changes in medial basal hypothalamic (MBH) gene expression of redox pathway enzymes nitric oxide synthase (NOS)-1 and NOS-2, heme oxygenase (HO)-1 and HO-2, Cu/Zn- and Mn-superoxide dismutases (SOD) and catalase were examined in adult male Wistar rats kept under an alternating regimen of light/dark. Half of the animals received melatonin (～60 μg/day) in the drinking water. After 1 month, rats were killed at six different time intervals, throughout a 24-h cycle. MBH mRNA levels were measured by real-time PCR analysis. In controls, gene expression of NOS-2 and HO-2 peaked at the early light phase while that of HO-1 showed a maximum at the middle of the dark phase. None of MBH mRNAs encoding NOS-1, Cu/Zn-SOD, Mn-SOD and catalase exhibited significant 24-h variations in control rats. Melatonin administration decreased significantly mRNAs for NOS-1, NOS-2, HO-1 and HO-2 as well as changed their 24-h profile. Melatonin augmented gene expression of the antioxidant enzymes Cu/Zn-SOD, Mn-SOD or catalase at certain time intervals only. The results are compatible with the view that the principal indirect (i.e. gene expression of redox pathway enzymes) effect of melatonin on redox pathway in the hypothalamus is mainly exerted via down-regulation of pro-oxidant enzyme mRNAs.     

Scavenger Enzyme Activities in Subcellular Fractions of White Clover (Trifolium repens L.) under PEG-induced Water Stress

Scavenger enzyme activities in subcellular fractions under polyethylene glycol (PEG)-induced water stress in white clover (Trifolium repens L.) were studied. Water stress decreased ascorbic acid (AA) content and catalase (CAT) activity and increased the contents of hydrogen peroxide (H₂O₂), thiobarbituric acid reactive substances (TBARS) (measure of lipid peroxidation), and activities of superoxide dismutase (SOD), its various isozymes, ascorbate peroxidase (APOX), and glutathione reductase (GR) in cellular cytosol, chloroplasts, mitochondria, and peroxisomes of Trifolium repens leaves. In both the PEG-treated plants and the control, chloroplastic fractions showed the highest total SOD, APOX, and GR activities, followed by mitochondrial fractions in the case of total SOD and GR activities, whereas cytosolic fractions had the second greatest APOX activity. However, CAT activity was the highest in peroxisomes, followed by the cytosol, mitochondria, and chloroplasts in decreasing order. Although Mn-SOD activity was highest in mitochondrial fractions, residual activity was also observed in cytosolic fractions. Cu/Zn-SOD and Fe-SOD were observed in all subcellular fractions; however, the activities were the highest in chloroplastic fractions for both isoforms. Total Cu/Zn-SOD activity, the sum of activities observed in all fractions, was higher than other SOD isoforms. These results suggest that cytosolic and chloroplastic APOX, chloroplastic and mitochondrial GR, mitochondrial Mn-SOD, cytosolic and chloroplastic Cu/Zn-SOD, and chloroplastic Fe-SOD are the major scavenger enzymes, whereas cellular CAT may play a minor role in scavenging of O₂⁻ and H₂O₂ produced under PEG-induced water stress in Trifolium repens.     

Endothelial function and vascular oxidative stress in long-lived GH/IGF-deficient Ames dwarf mice

Hypopituitary Ames dwarf mice have low circulating growth hormone (GH)/IGF-I levels, and they have extended longevity and exhibit many symptoms of delayed aging. To elucidate the vascular consequences of Ames dwarfism we compared endothelial O2(-) and H2O2 production, mitochondrial reactive oxygen species (ROS) generation, expression of antioxidant enzymes, and nitric oxide (NO) production in aortas of Ames dwarf and wild-type control mice. In Ames dwarf aortas endothelial O2(-) and H2O2 production and ROS generation by mitochondria were enhanced compared with those in vessels of wild-type mice. In Ames dwarf aortas there was a less abundant expression of Mn-SOD, Cu,Zn-SOD, glutathione peroxidase (GPx)-1, and endothelial nitric oxide synthase (eNOS). NO production and acetylcholine-induced relaxation were also decreased in aortas of Ames dwarf mice. In cultured wild-type mouse aortas and in human coronary arterial endothelial cells treatment with GH and IGF significantly reduced cellular O2(-) and H2O2 production and ROS generation by mitochondria and upregulated expression of Mn-SOD, Cu,Zn-SOD, GPx-1, and eNOS. Thus GH and IGF-I promote antioxidant phenotypic changes in the endothelial cells, whereas Ames dwarfism leads to vascular oxidative stress.     

The pathogenesis of L-arginine-induced acute necrotizing pancreatitis: inflammatory mediators and endogenous cholecystokinin.

This study was aimed at an assessment of the role of oxygen-derived free radicals, cytokines and endogenous cholecystokinin (CCK) in the pathogenesis of L-arginine (Arg)-induced acute pancreatitis in rat. We measured the levels of malonyl dialdehyde (MDA), glutathione peroxidase (GPx), catalase and superoxide dismutase (Mn- and Cu, Zn-SOD) in pancreatic tissue, the serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and CCK, and evaluated the protective effect of the xanthine oxidase inhibitor allopurinol and a novel CCK receptor antagonist KSG-504. Acute pancreatitis was induced in male Wistar rats by injecting 2x 250 mg/100 g body weight of Arg intraperitoneally in an 1-h interval, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. 200 mg x kg(-1) allopurinol 30 min before the first Arg treatment or 50 mg x kg(-1) KSG-504 30 min before and 6, 18 and 36 h after the first Arg injection was administered subcutaneously. Rats were killed at 6, 12, 24 and 48 h 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 h after the Arg injection (30,800 +/- 3,813 versus 6,382 +/- 184 U x L(-1) in the control) and normalized at 48 h. The tissue concentration of MDA was significantly elevated at 24 h, and reached the peak value at 48 h (5.00 +/- 1.75 versus 0.28 +/- 0.05 nM x mg(-1) 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 h, and the Cu, Zn-SOD activity was significantly lower at 12 h after the Arg injection as compared with the controls. Both the TNF-alpha and the IL-6 levels were already elevated significantly at 12 h and peak at 24 h versus the controls (19.1 +/- 7.9 U x mL(-1) and 57.6 +/- 11.2 pg x mL(-1) versus 3.1 +/- 0.8 U x mL(-1) and 15.2 +/- 3.1 pg x mL(-1), respectively). No significant changes in plasma CCK levels were observed. Allopurinol treatment markedly reduced the serum amylase elevation (12.631 +/- 2.257 U x L(-1) at 24 h), prevented the increase in tissue MDA concentration (0.55 +/- 0.09 nM x mg(-1) protein at 48 h) and significantly ameliorated the pancreatic edema, necrosis and inflammation at 48 h after Arg administration. KSG-504 administration did not exert any beneficial effect on the development of histopathological changes neither modified the serum amylase or cytokine levels. Oxygen-derived free radicals and cytokines are involved, while endogenous CCK does not seem to play a role in the pathogenesis of Arg-induced acute pancreatitis.     

Moderate intermittent hypoxia/hyperoxia: implication for correction of mitochondrial dysfunction

The purpose of this study was to appreciate the acute hypoxia-induced mitochondrial oxidative damage development and the role of adaptation to hypoxia/hyperoxia (H/H) in correction of mitochondrial dysfunction. It was demonstrated that long-term sessions of moderate H/H [5 cycles of 5 min hypoxia (10% O₂ in N₂) alternated with 5 min hyperoxia (30% O₂ in N₂) daily for two weeks]_attenuated basal and Fe²⁺/ascorbate-induced lipid peroxidation (LPO) as well as production of carbonyl proteins and H₂O₂ in liver mitochondria of rats exposed to acute severe hypoxia (7% O₂ in N₂, 60 min) in comparison with untreated animals. It was shown that H/H increases the activity of glutathione peroxidase (GPx), reduces hyperactivation of Mn-SOD, and decreases Cu,Zn-SOD activity as compared with untreated rats. It has been suggested that the induction of Mn-SOD protein expression and the coordinated action of Mn-SOD and GPx could be the mechanisms underlying protective effects of H/H, which promote the correction of the acute hypoxia-induced mitochondrial dysfunction. The increase in Mn-SOD protein synthesis without changes in Mn-SOD mRNA level under H/H pretreatment indicates that the Mn-SOD activity is most likely dependent on its posttranslational modification or on the redox state of liver mitochondria.     

Pretreatment with interferon-γ protects microglia from oxidative stress via up-regulation of Mn-SOD

Microglial cells, resident macrophage-like immune cells in the brain, are exposed to intense oxidative stress under various pathophysiological conditions. For self-defense against oxidative injuries, microglial cells must be equipped with antioxidative mechanisms. In this study, we investigated the regulation of antioxidant enzyme systems in microglial cells by interferon-γ (IFN-γ) and found that pretreatment with IFN-γ for 20 h protected microglial cells from the toxicity of various reactive species such as hydrogen peroxide (H₂O₂), superoxide anion, 4-hydroxy-2(E)-nonenal, and peroxynitrite. The cytoprotective effect of IFN-γ pretreatment was abolished by the protein synthesis inhibitor cycloheximide. In addition, treatment of microglial cells with both IFN-γ and H₂O₂ together did not protect them from the H₂O₂-evoked toxicity. These results imply that protein synthesis is required for the protection by IFN-γ. Among various antioxidant enzymes such as manganese or copper/zinc superoxide dismutase (Mn-SOD or Cu/Zn-SOD), catalase, and glutathione peroxidase (GPx), only Mn-SOD was up-regulated in IFN-γ-pretreated microglial cells. Transfection with siRNA of Mn-SOD abolished both up-regulation of Mn-SOD expression and protection from H₂O₂ toxicity by IFN-γ pretreatment. Furthermore, whereas the activities of Mn-SOD and catalase were up-regulated by IFN-γ pretreatment, those of Cu/Zn-SOD and GPx were not. These results indicate that IFN-γ pretreatment protects microglial cells from oxidative stress via selective up-regulation of the level of Mn-SOD and activity of Mn-SOD and catalase.     

Increased level of superoxide dismutase (SOD) activity in larvae of Chironomus ramosus (Diptera: Chironomidae) subjected to ionizing radiation

A battery of enzymes from the eukaryotic antioxidant defense system was measured in salivary gland and in whole body extract of fourth instar larvae of Chironomus ramosus with an objective of finding any clue for the dipteran insect's capacity to tolerate heavy doses of ionizing radiation. Levels of activity of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GSH-Px) were quantified in 30 days old larvae exposed to LD₂₀ dose of gamma radiation. Compared to controls, activity of Cu,Zn-SOD increased 3 to 4 fold and catalase 2 fold in response to ionizing radiation stress, while activities of GR and GSH-Px enzymes were decreased. Among the other SOD isoenzymes, our results showed comparable levels of Mn-SOD and Cu,Zn-SOD activity in control and irradiated groups of larvae. The increase in levels of the Cu,Zn-SOD isoenzyme was also confirmed by Western blot and zymography supported by densitometric quantification. No evidence of Fe-SOD was found in C. ramosus larvae. These findings could help to explain the persistence of natural populations of Chironomus in radioactively contaminated regions.     

Interleukin 1 protects rats against oxygen toxicity

We studied the effect of interleukin 1 alpha (IL-1) in the protection against O2 toxicity. Tracheal insufflation of IL-1 resulted in a dose-dependent protection against O2 toxicity. All control rats died within 3 days of O2 exposure. In contrast, 84, 71, and 20% of rats insufflated with 5, 1, and 0.2 microgram(s) IL-1 (150, 30, and 6 x 10(4) U), respectively, survived 100% O2 exposure for greater than 11 days. At 2.3 days after O2 exposure, control rats showed severe pulmonary injury, which insufflation of 5 microgram(s) IL-1 markedly attenuated. The protection against O2 toxicity was associated with a selective enhancement of pulmonary Mn-superoxide dismutase (Mn-SOD) activity in IL-1-insufflated rats. In rats insufflated with IL-1 that survived exposure to 100% O2 for 7 days, the activities of pulmonary Mn-SOD, Cu,Zn-SOD, catalase, and glutathione peroxidase were all increased. The increased pulmonary Mn-SOD activity demonstrated in IL-1-insufflated rats at 2.3 days after O2 exposure may contribute to the protection against acute O2 toxicity, and the markedly increased activities of all pulmonary antioxidant enzymes shown in rats insufflated with IL-1 that survived O2 exposure for 7 days may in part be responsible for the chronic adaptation of these rats to a 100% O2 environment.     

Aged garlic extract attenuates gentamicin induced renal damage and oxidative stress in rats

Gentamicin (GM) is an antibiotic whose clinical use is limited by its nephrotoxicity. Experimental evidences suggest a role of reactive oxygen species in GM-induced nephrotoxicity. Therefore, we investigated if aged garlic extract (AGE), an antioxidant, has a protective role in this experimental model. Four groups of male Wistar rats were studied: 1) Control (CT), injected subcutaneously (s.c.) and intraperitoneally (i.p.) with saline, 2) GM, treated s.c. with GM (70 mg/kg/12 hours/4 days), 3) AGE, treated i.p with AGE (1.2 mL/kg/12 hours/6 days), and 4) GM + AGE treated with GM and AGE. The treatment with AGE started two days before the first dose of GM (GM + AGE group) or saline (AGE group). Animals were sacrificed on day 5, and blood, urine, and kidneys were obtained. Nephrotoxicity was made evident by: 1) the increase in blood urea nitrogen and plasma creatinine, 2) the decrease in plasma glutathione peroxidase (GPx) activity and the urinary increase in N-acetyl-beta-D-glucosaminidase activity and total protein, and 3) necrosis of proximal tubular cells. These alterations were prevented or ameliorated by AGE treatment. Furthermore, AGE prevented the GM-induced increase in the renal levels of oxidative stress markers: nitrotyrosine and protein carbonyl groups and the decrease in manganese superoxide dismutase (Mn-SOD), GPx, and glutathione reductase (GR) activities. The protective effect of AGE was associated with the decrease in the oxidative stress and the preservation of Mn-SOD, GPx, and GR activities in renal cortex. These data suggest that AGE may be a useful agent for the prevention of GM-nephrotoxicity.     

Effect of sample preparation on analysis of superoxide dismutase activity and isoenzymes

The effect of superoxide dismutase (SOD) activity and isoenzyme pattern of detergents, incubation time, and sonication in the preparation of rat liver samples was investigated. The activity of the manganese form of the enzyme (Mn-SOD) was found to decrease significantly after 4 hr of incubation at room temperature, and activity of the copper, zinc form of the enzyme (Cu, Zn-SOD) was not changed significantly even after 24 hr, although levels were somewhat decreased. Sonication of the sample did not affect Cu, Zn-SOD activity, but total Mn-SOD activity was increased. Addition of detergents did not increase Mn-SOD activity when homogenates were sonicated, indicating that Mn-SOD is not membrane bound. Detergents also had no effect on Cu, Zn-SOD activity. None of the treatments investigated altered the isoenzyme patterns, providing evidence that these isoenzymes are not degradation products.     

Effect of cigarette smoke on placental antioxidant enzyme expression

Cigarette smoking is associated with systemic oxidative stress leading to an upregulation of antioxidant systems [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and heme oxygenase (HO)] in some tissues, but the response in the human placenta is unknown. The aim of this study was to determine the effect of cigarette smoke exposure on placental antioxidant expression in vivo, as well as the effect on antioxidant expression in the human trophoblast choriocarcinoma (HTR)-8SVNeo cell line. In the in vivo experiment, normal-term placentas were obtained following elective caesarean section. The chorionic villi (CV), anchoring villi (AV), and basal plate (BP) were dissected, and Western blot analysis was carried out for HO-1, HO-2, SOD, CAT, and GPx. In vitro experiment, a cigarette smoke extract (CSE) was prepared by bubbling the smoke form three cigarettes through 15 ml of RPMI. This 100% CSE was syringe filtered and diluted to 0.1, 0.5, 1, 2, 5, and 10% concentrations. HTR-8SVNeo cells were cultured with the CSE for 48 h. The cells were harvested, protein was extracted, and run on SDS-PAGE gels, and Western blot analysis was carried out for HO-1, HO-2, SOD, and CAT. Immunofluorescence for HTR-8SVNeo cells HO-1 was carried out following increasing concentrations of CSE. In the in vivo experiment, HO-1 and HO-2 expression was increased in the BP of placentas from smokers compared with nonsmokers. CAT, GPx, and SOD levels in all placental regions, as well as HO-1 and HO-2 expression in the AV and CV were unchanged. In the in vitro experiment, The 5%, 10%, and 20% dilutions were toxic to the cells. The 0.1% CSE solution did not significantly alter HO-1 expression. Treatment with the 0.5%, 1% and 2% CSE solutions resulted in a dose-dependent increase in HO-1 expression. None of the CSE treatments resulted in a significant alteration in HO-2, SOD, GPx, or CAT expression. HO-1 immunoflourescence confirmed the HO-1 expression studies. Cigarette smoke exposure increases HO-1 and HO-2 expression in the placental basal plate and increases HO-1 expression in the HTR-8SVNeo cell line. Increased HO-1 and HO-2 protein expression may increase the production of the antioxidants biliverdin and bilirubin, which are products of heme metabolism. This could function to reduce the oxidative load that is released into the maternal plasma from the preeclamptic placenta and may contribute to the observed decreased incidence of preeclampsia in smokers.     

Superoxide dismutase in vesicular arbuscular-mycorrhizal red clover plants

The isoenzymatic pattern of Superoxide dismutase (SOD; EC 1.15.1.1) was studied in the symbiosis of Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe-Trifolium prarense L A Cu.Zn-SOD (M, 40500) was found in spores of G. mosseae . while one Mn-SOD (Mn-SOD I) and two Cu.Zn-SODs (Cu.Zn-SOD 1 and Cu.Zn-SOD II) were present in both roots and leaves of T. pratense . Molecular masses for Cu.Zn-SOD I and Cu.Zn-SOD II were 31000 and 34300. respectively. However, when T. prateme and G. mosseae were associated, mycorrhizal roots showed two new iso-zymes, Mn-SOD II and mycCu.Zn-SOD, which have relative molecular masses of 37 800 and 33 300, respectively. The mycCu.Zn-SOD was found to be specific for this association, whereas Mn-SOD II was also present in nodules of Rhizobium-T. pra-tense . Results suggest that both enzymes are induced in the T. praiense roots in response to invasion by mycorrhizal fungi, perhaps as a result of an increase in the generation of O-₂ radicals in plant roots.     

9,10-Phenanthraquinone in diesel exhaust particles downregulates Cu,Zn-SOD and HO-1 in human pulmonary epithelial cells: intracellular iron scavenger 1,10-phenanthroline affords protection against apoptosis

9,10-Phenanthraquinone (PQ), a major quinone contained in diesel exhaust particles and atmospheric PM(2.5), undergoes one-electron reduction by flavin enzymes such as NADPH-cytochrome P450 reductase, leading to production of reactive oxygen species in vitro. We have detected an ESR signal for superoxide (O(2)(-)) and hydroxyl radicals ((.)OH) by the spin trap method when PQ was mixed with P450 reductase, NADPH, and iron(III). When we examined the effects of PQ on A549 human pulmonary epithelial cells, PQ induced apoptosis with a LC(50) of approximately 7 microM. Formation of protein carbonyls was also detected in cells after treatment with PQ, suggesting that PQ induces oxidative damage. Iron chelators such as 1,10-phenanthroline (OP), desferrioxamine mesylate, and deferiprone respectively afforded protection against the toxic effects of PQ. Furthermore, treatment of A549 cells with 10-20 microM PQ for 12 h specifically down-regulated protein levels of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) and heme oxygenase-1 (HO-1) by more than 50%. Pretreatment of cells with OP (10 microM) markedly reduced the down-regulation of Cu,Zn-SOD and HO-1 and protein carbonyl formation in response to PQ. The inhibitor of Cu,Zn-SOD, diethyldithiocarbamate, enhanced the toxic effects of 5 microM PQ. The present findings suggest that PQ causes iron-mediated oxidative damage that is exacerbated by the concomitant down-regulation of Cu,Zn-SOD.