草鱼线粒体型超氧化物歧化酶的生化遗传特性

超氧化物歧化酶 (SOD)是一种对生物细胞保护至关重要、在进化上比较保守的酶。因此 ,超氧化物歧化酶作为分子钟或分子标记已被广泛应用于生物进化研究、群体遗传结构分析以及品系鉴定。但鱼类SOD的生物化学和遗传学特性都尚未进行过系统和深入的研究。为使这一重要的分子标记能更好地应用于鱼类遗传育种、种质资源保护以及进化研究 ,本实验采用聚丙烯酰胺梯度凝胶垂直电泳法 ,研究了草鱼线粒体型超氧化物歧化酶 (fm SOD)的同功酶形式 ,生化遗传表型、亚基组成以及金属类型。实验结果表明 ,草鱼fm SOD有三种不同的同功酶形式 ;按从正极到负极的排列分别命名为fm SOD 1 ,fm SOD 2 ,fm SOD 3。这三种不同的fm SOD在草鱼群体中可构成 3种不同的生化遗传学表型 :表型 1个体只含有迁移率最快的fm SOD 1同功酶 ;表型3个体只含有迁移率最慢的fm SOD 3同功酶 ;而表型 2个体中含有所有三种不同形式的同功酶。在野生草鱼群体中 ,存在所有三种表现型 ;而在基因纯合型的雌核发育草鱼群体中只检测到表型 1和表型 3。野生草鱼群体中三种表现型的个体数之比符合一对等位基因分离的 1∶2∶1孟德尔遗传分离比例。由这些实验结果得出以下结论 :(1 )草鱼fm SOD是由细胞核DNA上的基因所编码而不是由线粒体DNA上的基因所编码的     

茶多酚对NASH 大鼠肝脏组织VEGF 及氧化应激的影响

目的:茶多酚对NASH大鼠肝脏组织VEGF及氧化应激的影响。方法:雄性SD大鼠30只,随机分为3组,正常对照组、模型组、茶多酚治疗组。正常组普通饲料喂养,模型组喂高脂饮食,茶多酚治疗组在高脂饮食12周后茶多酚(150mg(/kg.d)灌胃治疗,16周末处死各组大鼠,留取肝脏组织,观察各组大鼠肝组织病理改变,测定其肝脏丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性以及血管内皮生长因子(VEGF)、Ⅰ、Ⅲ型胶原的表达。结果:模型组大鼠肝组织中SOD活性降低而MDA含量以及VEGF、Ⅰ、Ⅲ型胶原表达均明显高于正常组。茶多酚治疗可减轻肝纤维化程度,显著升高肝组织中SOD活性、降低MDA含量以及VEGF、Ⅰ、Ⅲ型胶原表达水平。结论:茶多酚可通过抑制肝纤维化组织VEGF表达,降低肝组织氧化应激水平而发挥抗肝纤维化作用。     

用于脑缺血小鼠海马SOD1表达的改进灌注固定法

常规灌注固定法多用于兔和大鼠等较大动物,并存在一些不足。改进了灌注固定法流程、灌注溶液的配方、流速、用量以及灌注装置,将其用于在显微操作下制备的缺血再灌注C57BL/6N小鼠模型,并对其海马进行H.E染色和免疫组织化学SOD1基因表达。结果显示,改进的灌注固定法使组织切片结构更加清晰,海马免疫阳性神经元定位于胞浆。缺血再灌注组(24hI/R)海马神经元SOD1表达比假手术对照组(sham-o)减少,而高压氧治疗组(24hHBO)SOD1表达有所恢复。表明改进的灌注固定法用于缺血再灌注C57BL/6N小鼠海马SOD1基因表达效果良好,结果可靠。实验结果提示,高压氧的治疗机制之一可能是通过增加SOD1基因表达而实现的。     

阿司匹林联合神经节苷脂治疗脑梗塞的临床疗效观察

目的:探讨阿司匹林联合神经节苷脂治疗脑梗塞的临床疗效及可能机制。方法:选择我院2015年5月到2018年3月接诊的90例脑梗塞患者,依照抽签法将其分为实验组和对照组,每组45例。两组患者均给予常规支持治疗,对照组在此基础上给予阿司匹林治疗,实验组在对照组的基础上给予单唾液酸四己糖神经节苷脂(Monosialyl tetrahexose ganglioside, GM1)治疗。据患者美国国立卫生研究院卒中量表(National Institutes of Health Stroke Scale, NIHSS)和Barthel指数评分的改善情况,比较两组的疗效,以及治疗前后血清过氧化脂质(lipid peroxide, LPO)、超氧化物歧化酶(superoxide dismutase, SOD)、丙二醛(malondialdehyde, MDA)、一氧化氮(nitric oxide, NO)水平的变化。结果:治疗后,实验组有效率为96.86%,显著高于对照组(78.13%,P<0.05)。两组治疗后血清SOD水平及Barthel指数均较治疗前显著上升,而血清LPO、MDA、NO水平及NIHSS评分均较治疗前显著下降,实验组血清SOD水平及Barthel指数显著高于对照组,血清LPO、MDA、NO水平及NIHSS评分均明显低于对照组(P<0.05)。结论:阿司匹林联合GM1能提高脑梗塞的疗效,可能与有效提高血清SOD水平及降低LPO、MDA、NO水平有关。     

缬沙坦联合通心络胶囊对糖尿病心肌病患者血清肌钙蛋白及SOD水平的影响

目的:探讨缬沙坦联合通心络胶囊对糖尿病心肌病患者血清肌钙蛋白,SOD及生活质量的影响。方法:收集我院就诊或住院治疗的60例糖尿病心肌病患者,随机分为实验组和对照组,每组30例。对照组患者给予缬沙坦口服治疗,实验组患者在此基础上给予通心络治疗。检测并比较两组患者治疗前后血清cTnI、生活质量、SOD、运动耐量的变化情况。结果:与治疗前相比,两组患者治疗后血清cTnI和生活质量评分均下降,而SOD和运动耐量水平均升高,差异具有统计学意义(P0.05);与对照组相比,实验组患者治疗后血清cTnI和生活质量评分较低,而SOD和运动耐量水平较高,差异具有统计学意义(P0.05)。结论:缬沙坦联合通心络胶囊能够降低糖尿病心肌病患者cTnI、生活质量评分,升高其SOD以及运动耐量水平,对临床具有指导意义。     

银杏叶提取物联合骨髓间充质干细胞治疗(Ⅰ型)糖尿病大鼠疗效观察

目的:探讨银杏叶提取物联合骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)治疗(Ⅰ型)糖尿病大鼠的效果.方法:用腹腔内注射链脲酶菌素方法造模Ⅰ型糖尿病wistar大鼠,BMSCs治疗(1× 106/个)(DM)大鼠的同时,给予银杏叶提取物(Ginkgo biloba extract,GBE)治疗20天,同时设立单纯BMSCs治疗组,单纯GBE治疗组,糖尿病模型组以及正常对照组.分时段监测各组大鼠随机血糖、胰岛素、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)以及超氧化物歧化酶(SOD)水平.结果:与其它各组相比,与正常对照组相比DM组血糖水平明显高于GBE组和BMSCs组,BMSCs联合GBE治疗组的大鼠MDA水平明显降低于各治疗组,胰岛素、GSH-Px和SOD水平则明显高于其他对照治疗组.结论:BMSCs联合GBE治疗Ⅰ型DM大鼠,可以明显降低大鼠的血糖和氧化应激水平,其效果好于单独银杏叶提取物治疗或BMSCs治疗.     

姜黄素灌胃对糖尿病大鼠心肌酶和氧化指标的影响

目的:探讨姜黄素灌胃对糖尿病心脏病变大鼠心肌酶和氧化指标的影响。方法:将成年雄性SD大鼠随机分为对照组、糖尿病组、姜黄素治疗2周组与姜黄素治疗4周组。取心室肌组织匀浆分别检测心肌酶、超氧化物歧化酶(Superoxide dismutase,SOD)和丙二醛(Malondialdehyde,MDA)的含量。结果:糖尿病组与对照组比较,心肌酶天冬氨酸氨基转移酶(Aspartate transaminase,AST)、乳酸脱氢酶(Lactic dehydrogenase,LDH)、肌酸激酶(Creatinekinase,CK)、肌酸激酶同工酶(Creatine kinase isoenzyme-MB,CK-MB)均增高(P0.01)。心肌氧化代谢产物MDA含量升高(P0.01),抗氧化损伤的SOD含量降低(P0.01);姜黄素治疗组与糖尿病组相比,各心肌酶含量有所下降,治疗4周组有明显统计学差异(P0.01)。同时心肌SOD和MDA含量在治疗组均有显著改善(P0.05或P0.01),治疗4周组心肌组织SOD含量较2周组明显升高(P0.05)。结论:姜黄素灌胃可以减轻糖尿病大鼠心肌损伤,提高抗氧化能力。     

维生素B12 联合依帕司他对糖尿病周围神经病患者血清SOD及MDA水平的影响

目的:探讨维生素B12联合依帕司他对糖尿病周围神经病患者血清超氧化物歧化酶(SOD)及丙二醛(MDA)水平的影响。方法:收集我院收治的98例2型糖尿病伴周围神经病变患者,随机分为实验组和对照组,每组49例。对照组患者给予依帕司他片50 mg/次,3次/d;实验组患者在对照组基础上给予维生素B12 25~100μg/次,1次/d治疗连续4周。观察并比较两组患者周围神经评分(TCSS评分)、血清SOD、MDA水平以及临床疗效。结果:与治疗前相比,两组患者的TCSS评分、MDA水平均下降血清SOD水平升高,差异具有统计学意义(P0.05);与对照组相比,实验组患者的TCSS评分、丙二醛(MDA)水平较低,血清SOD水平较高差异具有统计学意义(P0.05);与对照组相比,实验组患者的治疗总有效率较高,差异具有统计学意义(P0.05);两组患者均未有明显的不良反应差异无统计学意义(P0.05)。结论:维生素B12联合依帕司他能够改善糖尿病周围神经病患者血清MDA、SOD水平,对临床有指导意义。     

康复新液联合胸腺五肽局部应用对口腔溃疡的疗效及对血清TNF-α、IL-6、SOD、SIgA、IgG的影响

目的:研究康复新液联合胸腺五肽局部应用对口腔溃疡的疗效及对血清肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白介素-6(Interleukin,IL-6)、超氧化物歧化酶(Superoxide dismutase,SOD)、唾液分泌型免疫球蛋白(secretory im-munoglobulin A,SIgA)、免疫球蛋白(immunoglobulin,IgG)的影响。方法:选取2014年12月至2016年12月我院收治的86例口腔溃疡患者,按照随机数表法分为康复新液组(n=43)和联合治疗组(n=43)。康复新液组患者采取康复新液治疗,联合治疗组则采取康复新液联合胸腺五肽局部应用治疗。观察并比较两组患者临床治疗效果、症状改善情况、疼痛缓解时间和溃疡愈合时间、血清TNF-α、IL-6、SOD水平变化情况、SIgA和IgG水平以及不良反应和复发情况。结果:与治疗前比较,两组患者治疗72 h后疼痛程度均明显改善,溃疡直径显著缩小,总积分明显下降,总积分下降指数显著攀升(P0.05);血清TNF-α、IL-6水平明显下降,血清SOD水平明显升高(P0.05)。与康复新液组患者相比,联合治疗组患者总有效率明显升高(P0.05),疼痛程度、溃疡直径、总积分、总积分下降指数改善情况更优(P0.05),缓解时间和溃疡愈合时间明显缩短(P0.05),血清TNF-α、IL-6水平下降和血清SOD水平升高程度更明显(P0.05)。两组患者治疗后SIgA水平较治疗前明显升高,IgG水平较治疗前显著降低,且联合治疗组以上指标的改善情况显著优于康复新液组(P0.05),复发率明显较低(P0.05)。结论:康复新液联合胸腺五肽局部应用治疗口腔溃疡临床治疗效果明显优于康复新液单药治疗,可有效缓解疼痛、减轻患者相关症状、加速愈合,其机制可能与降低血清TNF-α、IL-6水平及提高血清SOD水平有关。     

质子泵抑制剂兰索拉唑和奥美拉唑对胃溃疡患者MDA，SOD及NO的影响

目的:探讨兰索拉唑和奥美拉唑两种不同质子泵抑制剂对胃溃疡患者治疗效果及对丙二醛(MDA)、超氧化物歧化酶(SOD)及一氧化氮(NO)水平的影响。方法:收取2013年9月至2015年6月之间于我院接受治疗的胃溃疡患者98例作为研究对象,根据随机数字表法将98例患者平均分为A、B两组,两组各包含患者49例。A组患者使用兰索拉唑治疗,B组患者使用奥美拉唑治疗,两组均进行连续30 d治疗。对两组患者治疗效果、症状缓解情况、MDA、SOD及NO水平、不良反应以及治疗费用进行比较。结果:A组患者痊愈率及总有效率分别为63.27%及91.84%,B组患者痊愈率及总有效率分别为61.22%及93.88%。两组患者治疗效果比较无显著差异(P0.05)。治疗后,两组患者腹胀、腹痛、上腹部烧灼及反酸症状与治疗前相较有显著差异(P0.05),但治疗后组间比较无明显差异(P0.05)。治疗后两组MDA显著降低,SOD及NO显著升高,其中A组变化幅度大于B组,差异有统计学意义(P0.05)。A组患者不良反应发生率为20.41%,明显高于B组的6.12%(P0.05)。B组患者质子泵抑制剂治疗费用明显低于A组。结论:兰索拉唑和奥美拉唑两种质子泵抑制剂对胃溃疡患者疗效相当,兰索拉唑在MDA、SOD及NO水平改善上具有优势,但奥美拉唑安全性更高且治疗费用相对较低。应当结合患者具体情况选择适宜的治疗方案。     

Effect of MCI-186 on Postischemic Reperfusion Injury in Isolated Rat Heart

MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one) is a newly developed antioxidant which has been shown to reduce brain edema in cerebral ischemia through inhibition of the lipoxygenase pathway of arachidonic acid. However, its effect on myocardial reperfusion injury after prolonged ischemia has not yet been demonstrated. We compared the mode of the effect of MCI-186 and recombinant human CuZn superoxide dismutase (rh-SOD) in isolated perfused rat hearts subjected to 60-min ischemia followed by 60-min reperfusion. Left ventricular developed pressure (LVDP), necrotic area and the release of creatine phosphokinase (CPK) and endogenous CuZn superoxide dismutase (endoge-SOD) were measured to evaluate myocardial damage. The decrease in left coronary flow (CBF) was measured as an index of the damage of left coronary circulation. MCI-186 (17.5 mg/L) was perfused for 10 min in the MCI group and rh-SOD (70 mg/L) was perfused during the reperfusion period in the SOD group starting 5 min prior to reperfusion. The release patterns of CPK and endoge-SOD were analyzed to elucidate the difference in the mode of protection of MCI-186 and rh-SOD. The LVDP remained higher in both MCI and SOD groups than that of control (76 ± 1, 77 ± 2 and 69 ± 1% of preischemic value, respectively). The necrotic area was significantly attenuated in both MCI and SOD groups compared with that in the control group (16 ± 1,14 ± 1 and 32 ± 170, respectively, p<0.05). Total CPK release was lower in both MCI and SOD groups thfn in the control (78 ± 7, 100 ± 2 and 116 ± 4 × 10³ units/g myocardium respectively). The decrease in CPK release was more marked in the MCI group than that in the SOD group (p<0.05). The reduction in CBF was significantly attenuated by the treatment with rh-SOD or MCI-186, but the effect was much higher in the SOD group than in the MCI group (69 ± 5, 58 ± 2, and 48 ± 2% in SOD, MCI and control groups, respectively). The release pattern of endoge-SOD was identical to that of CPK and thus this did not distinguish the mode of effect of MCI-186 from that of rh-SOD. These results indicate that MCI-186 reduces reperfusion injury in isolated perfused hearts with prolonged ischemia and the effect is more closely related to the reduction of myocyte damage than the preservation of the coronary circulation.     

Superoxide dismutases: a physiopharmacological update

Reactive oxygen species (ROS) are known participants in several cellular processes. Superoxide anion radical, one example of ROS, forms as a result of normal cellular respiration and is usually cleared successfully by superoxide dismutase (SOD) and other radical scavengers. However, when superoxide exceeds the clearance capacity of SOD and other ROS scavengers, superoxide initiates a number of pathologic processes. This review examines pathologies involving superoxide, including: cancer, neurodegenerative diseases, ischemia/reperfusion injury, and inflammation. We will also explore the basic science principles of superoxide and SOD, including: SOD evolution, SOD mutations, biochemistry, physiology, and pathophysiology. In reviewing the basic science, clinical pathology, and therapeutic research, we hope to clearly demonstrate plausible pharmacologic targets of action. We have revised data about basic science, clinical pathology and therapeutic research in an effort to propose plausible pharmacological targets of action. The understanding of these aspects is critical in the accomplishment of a successful clinical intervention.     

Chemical modification of superoxide dismutase. Extension of plasma half life of the enzyme through its reversible binding to the circulating albumin

Protection of organisms from oxidative stress is one of the major prerequisites for aerobic life. Since intravenously injected Cu++/Zn++-type superoxide dismutase (SOD) rapidly undergoes renal glomerular filtration and appears in urine in its intact form, its clinical use as a scavenger for superoxide radicals has been highly limited. To test whether reversible interaction of SOD with plasma albumin might decrease the rate of disappearance of the enzyme from the circulation, the lysyl residues of the human erythrocyte-type enzyme were covalently linked with poly-(styrene-co-maleic acid) butyl ester (SMA) via amide linkage. Affinity chromatographic analysis by an albumin-Sepharose column revealed that the enzyme samples labeled with SMA (SMA-SOD) tightly bound to the column, while unmodified SOD was eluted in the unbound fractions. SMA-SOD bound to the column could be eluted by the buffer solution containing 0.1% sodium dodecylsulfate. In vivo analysis revealed that intravenously administered SMA-SOD circulated bound to albumin with an extremely long half-life (6 h), while unmodified SOD rapidly underwent renal glomerular filtration with a plasma half-life of 4 min. Thus, SMA-SOD may effectively dismutase superoxide radicals in the circulation.     

Effects of antioxidant gene therapy on retinal neurons and oxidative stress in a model of retinal ischemia/reperfusion

Retinal ischemia/reperfusion (I/R) results in neuronal death and generation of reactive oxygen species. The aim of this study was to investigate the neuroprotective effect of manganese superoxide dismutase (SOD2) on retinal ganglion cells (RGCs) in an I/R-induced retinal injury model. One eye of each Wistar rat was pretreated with recombinant adeno-associated virus containing the SOD2 gene (AAV-SOD2) or recombinant AAV containing the GFP gene (AAV-GFP) by intravitreal injection 21 days before initiation of I/R injury. Retinal I/R injury was induced by elevating intraocular pressure for 1h, and reperfusion was established immediately afterward. The number of RGCs and the inner plexiform layer (IPL) thickness were measured by Fluorogold retrograde labeling and hematoxylin and eosin staining at 6 h, 24 h, 72 h, and 5 days after injury. Superoxide anion, the number of RGCs, IPL thickness, malondialdehyde (MDA) level, 8-hydroxy-2-deoxyguanosine (8-OHdG) level, MnSOD (manganese superoxide dismutase) activity, and nitrotyrosine level were measured by fluorescence staining, immunohistochemistry, and enzyme-linked immunosorbent analysis at 5 days after I/R injury. Severe RGC loss, reduced IPL thickness, reduced MnSOD activity, and increased superoxide ion, MDA, 8-OHdG, and nitrotyrosine production were observed after I/R injury. Administration of AAV-SOD2 significantly reduced the levels of superoxide ion, MDA, 8-OHdG, and nitrotyrosine and prevented the damage to RGCs and IPL. Delivery of the antioxidant gene inhibited I/R-induced RGC and IPL damage by reducing oxidative stress and nitrative stress, suggesting that MnSOD may be relevant for the neuroprotection of the inner retina from I/R-related diseases.     

The protective action of melatonin on indomethacin-induced gastric and testicular oxidative stress in rats

Reactive oxygen species and lipid peroxidation play a role in the pathogenesis induced by the non-steroidal anti-inflammatory drug indomethacin. Melatonin (MLT) protection against indomethacin-induced oxidative tissue injury was investigated in gastric mucosa and testis of rats. MLT was administered intragastrically (i.g.) 30 min before the administration to fasted rats of 20 mg indomethacin/kg rat given i.g.. The area of gastric lesion as well as thiobarbituric acid reactive substances (TBARS) and lactate dehydrogenase (LDH) activity were found to be significantly increased 4 h after administration of indomethacin in rat gastric mucosa and testis indicating acute oxidative injury. MLT pretreatment reduced gastric lesion area to 80% of the indomethacin-treated rats and reduced the rise in TBARS concentration. MLT treatment reduced the LDH activity increase in testis but not in gastric mucosa. In indomethacin-treated rats, both the cytosolic Cu,Zn superoxide dismutase (Cu,Zn-SOD) and mitochondrial Mn-SOD activities were significantly diminished in gastric mucosa as well as the total SOD activity in testis. In addition, glutathione (GSH) content in both tissues was markedly decreased following indomethacin treatment. Pretreatment with MLT significantly ameliorated both the inhibition of SOD activity and the decreased GSH content in both tissues. Thus, these results show the effective antiperoxidative and preventive actions of MLT against indomethacin-induced gastric mucosal damage and testicular oxidative injury and we propose that this action might be relevant for its use with other free radical generating drugs.     

氧自由基在应激性胃溃疡中的发病学意义

本工作研究了氧自由基在大鼠冷冻束缚应激性胃溃疡中的发病学意义。实验结果如下:(1)以超氧自由基清除剂超氧化物歧化酶(SOD)或羟自由基清除剂二甲亚砜和甘露醇预先处理大鼠,均可显著地减轻胃粘膜损伤;(2)应激时,胃粘膜内的脂质过氧化分解产物丙二醛的含量显著升高;(3)组织化学的研究显示,胃粘膜层含有丰富的黄嘌呤氧化酶,其活性在应激时明显升高,预先用别嘌呤醇处理大鼠以抑制黄嘌呤氧化酶的活性,可使胃粘膜损伤显著减轻。上述结果提示,氧自由基是应激性胃溃疡的重要致病因子,而黄嘌呤氧化酶活性的升高似可能为应激时氧自由基生成增加的重要原因。     

Scavenging ROS: superoxide dismutase/catalase mimetics by the use of an oxidation-sensitive nanocarrier/enzyme conjugate

Reactive Oxygen Species (ROS) are quintessential inflammatory compounds with oxidizing behavior. We have successfully developed a micellar system with responsiveness at the same time to two of the most important ROS: superoxide and hydrogen peroxide. This allows for an effective and selective capture of the two compounds and, in perspective, for inflammation-responsive drug release. The system is composed of superoxide dismutase (SOD) conjugated to oxidation-sensitive amphiphilic polysulfide/PEG block copolymers; the conjugate combines the SOD reactivity toward superoxide with that of hydrophobic thioethers toward hydrogen peroxide. Specifically, here we have demonstrated how this hybrid system can efficiently convert superoxide into hydrogen peroxide, which is then "mopped-up" by the polysulfides: this modus operandi is functionally analogous to the SOD/catalase combination, with the advantages of (a) being based on a single and more stable system, and (b) a higher overall efficiency due the physical proximity of the two ROS-reactive centers (SOD and polysulfides).     

Copper- and zinc-containing superoxide dismutase can act as a superoxide reductase and a superoxide oxidase

The copper- and zinc-containing superoxide dismutase can catalyze the oxidation of ferrocyanide by O(2) as well as the reduction of ferricyanide by O(2). Thus, it can act as a superoxide dismutase (SOD), a superoxide reductase (SOR), and a superoxide oxidase (SOO). The human manganese-containing SOD does not exert SOR or SOO activities with ferrocyanide or ferricyanide as the redox partners. It is possible that some biological reductants can take the place of ferrocyanide and can also interact with human manganese-containing superoxide dismutase, thus making the SOR activity a reality for both SODs. The consequences of this possibility vis à vis H(2)O(2) production, the overproduction of SODs, and the role of copper- and zinc-containing superoxide dismutase mutations in causing familial amyotrophic lateral sclerosis are discussed, as well as the likelihood that the biologically effective SOD mimics, as described to date, actually function as SORs.     

Liposome-entrapped superoxide dismutase reduces ischemia/reperfusion ‘oxidative stress’ in gerbil brain

Bilateral common carotid artery occlusion (15 min.) followed by two hours of recirculation reduced mitochondrial superoxide dismutase (SOD) and glutathione reductase (GR) activities, and increased susceptibility of mitochondrial membranes to in vitro lipid peroxidation in brain regions (i.e., cortex, striatum and hippocampus) of Mongolian gerbil. Intraperitoneal bolus injection (2 mg/kg b.w.) of liposome-entrapped CuZn superoxide dismutase (l-SOD) increased the endogenous SOD activity in normal brain tissue and, when given at the end of ischemia, counteracted both the ischemic reduction of endogenous SOD and the increased peroxidation of mitochondrial membranes. 1-SOD treatment was ineffective in reducing brain swelling, suggesting that superoxide radicals are not a main participant in the process of (post)ischemic brain edema formation.     

Hydrogen peroxide damages the zinc-binding site of zinc-deficient Cu,Zn superoxide dismutase

Mutations in Cu,Zn superoxide dismutase (Cu,Zn SOD) account for approximately 20% of cases of familial amyotrophic lateral sclerosis (ALS), a late-onset neurodegenerative disease affecting motor neurons. These mutations decrease protein stability and lower zinc affinity. Zinc-deficient SOD (Cu,E SOD) has altered redox activities and is toxic to motor neurons in vitro. Using bovine SOD, we studied the effects of hydrogen peroxide (H(2)O(2)) on Cu,E SOD and Cu,Zn SOD. Hydrogen peroxide treatment of Cu,E SOD inactivated zinc binding activity six times faster than superoxide dismutase activity, whereas inactivation of dismutase activity occurred at the same rate for both Cu,Zn SOD and Cu,E SOD. Zinc binding by Cu,E SOD was also damaged by simultaneous generation of superoxide and hydrogen peroxide by xanthine oxidase plus xanthine. Although urate, xanthine, and ascorbate can protect superoxide dismutase activity of Cu,Zn SOD from inactivation, they were not effective at protecting Cu,E SOD. Hydrogen peroxide induced subtle changes in the tertiary structure but not the secondary structure of Cu,E SOD as detected by near and far UV circular dichroism. Our results suggest that low levels of hydrogen peroxide could potentially enhance the toxicity of zinc deficient SOD to motor neurons in ALS by rendering zinc loss from SOD irreversible.