氧化苦参碱对心肌缺血再灌注损伤MDA变化及超微结构的影响

近年来研究发现,氧化苦参碱(OMT)能够清除体外模拟Fenton反应产生的羟自由基,并且能够抑制肿瘤坏死因子(TNF)的释放。2000～2004年,我们通过测定间接反映脂质氧化及部分反映氧自由基的丙二醛(MDA)和分析心肌细胞的超微结构,重点探讨OMT在缺血再灌注过程中对心肌的保护作用。     

老年心绞痛患者银杏叶黄酮治疗前后的自由基变化

以邻苯三酚自氧化抑制法和硫代巴比妥酸反应产物比色分析法检测经用“天保宁”(银杏叶制剂)治疗50例心绞痛患者前后红细胞超氧化物歧化酶(E—SOD)活性及血浆过氧化脂质(P—LPO)和红细胞过氧化脂质(E—LPO)含量的结果表明,与治疗前相比,治疗后的E-SOD平均活性显著升高(P<0.01),P—LPO和E—LPO平均含量均显著降低(P<0.01)。提示老年心绞痛患者体内的病理性氧自由基反应和脂质过氧化反应在治疗后明显减缓,银杏叶黄酮具有较强的抗氧自由基损伤和抗脂质过氧化损伤作用。     

狼疮肾炎患者氧化损伤及抗氧化功能的评价

狼疮肾炎 (ｌｕｐｕｓｎｅｐｈｒｉｔｉｓ,ＬＮ)是一种免疫复合物介导性炎症 ,免疫复合物的沉积可激活炎症细胞释放大量的一氧化氮 (ＮＯ)、超氧阴离子和其他活性氧自由基 (ＲＯＳ) ,使机体产生氧化损伤 ,加重肾脏损害[1] 。而泼尼松与大剂量环磷酰胺冲击 (Ⅳ ＣＴＸ)治疗对机体氧化损伤及抗氧化水平的影响国内外未见报道。我们检测ＬＮ患者在泼尼松及Ⅳ ＣＴＸ治疗前后血中ＮＯ、脂质过氧化物 (ＬＰＯ)、超氧化物歧化酶(ＳＯＤ)、谷胱甘肽过氧化物酶 (ＧＳＨ ｐｘ)和谷胱甘肽 (ＧＳＨ)的含量 ,旨在探讨上述治疗方法对ＬＮ患者血清氧化指标…     

去铁敏减少体外循环时中性粒细胞介导的氧自由基生成

已有大量研究证实体外循环时补体激活,以及由此产生的趋化因子 C_(5a)激活多形核中性粒细胞(PMN),使之释放大量氧自由基而损伤组织。氧自由基导致组织脂质过氧化时需要铁离子参与,因此应用铁离子螯合剂去铁敏(Deferoxamine)可有效防止氧自     

白介素-10在抗肝纤维化中的作用

白介素-10(IL-10)是一种主要由Th_2细胞产生,抑制Th_1细胞释放细胞因子的免疫调节性细胞因子。IL-10可通过抑制库弗细胞活化及炎性介质、细胞因子、氧自由基等释放,抑制核因子-κB活性,参与调节肝再生反应等来发挥抗肝纤维化作用。IL-10有望成为治疗肝纤维化的重要药物。     

体外循环中氧自由基的产生及维生素E的作用

<正> 氧使H_2O_2还原成水,自身形成细胞毒性氧自由基使不饱和脂肪酸产生脂质过氧反应,损害细胞膜结构。机体内抗自由基保护系统有超氧自由基岐化酶(SOD)、过氧化酶(CAT)、谷胱甘肽过氧化酶(Gsh-Px)及某些内源性物质如抗坏血酸及维生素E等。体外循环(CPB)可引起氧自由基增加,抑制体内正常抗氧自由基系统,破坏细胞完整性。本实验目的:(1)验证CPB对细胞毒性氧自由基,脂质过氧化物作用和在肺内白细胞滞留与血浆维生素F、维生素C的关系。(2)观察预服外源性维生素E抗细胞毒氧自由基的效应。     

短膜虫酪氨酸转氨酶的纯化与鉴定

本文报告了短膜虫(Crithidia fasculata)酪氨酸转氨酶(TAT)的纯化和鉴定方法。TAT在辅酶存在时,催化酪氨酸与适当酮酸间的氨基转移作用。用改良Diamondstone法检测其活性,每份分析液总量为0.93ml,其中含4mM L-酪氨酸、50mM磷酸吡哆醛、10mM α-酮戊二酸和0.1ml酶样品。以上各成分均以100mM pH7.6磷酸钾缓冲液处理。37℃反应15分钟。以0.07ml 10N KOH     

白介素-10在抗肝纤维化中的作用

白介素-10(IL-10)是一种主要由Th2细胞产生，抑制Th1细胞释放细胞因子的免疫调节性细胞因子。IL-10可通过抑制库弗细胞活化及炎性介质、细胞因子、氧自由基等释放，抑制核因子-κB活性，参与调节肝再生反应等来发挥抗肝纤维化作用。IL-10有望成为治疗肝纤维化的重要药物。     

氧自由基与消化道疾病

正常情况下,大多数分子氧在细胞色素氧化系统内,经完全还原(四价还原),生成水和能量。约有1％—2％的分子氧呈单价还原,通过一系列单电子传递,产生具有细胞毒性的超氧自由基O_2~-、H_2O_2与羟自由基HO·,它们是一类活性极高含不成对电子的原子或官能团,由于正常组织内存在氧自由基清除酶,使自由基的产生及清除处于平衡状态。超氧化     

氧化应激对心肌细胞的影响

氧化应激 (Oxidativestress)是指[1 ] :“促氧化与抗氧化之间的平衡失调而倾向于前者 ,导致可能的损害”。促氧化是由体内的各种氧化剂来实现的 ,而最主要的氧化剂是活性氧 (reactiveoxygenspecies,ROS)。ROS是指一组含有化学性质活泼的含氧功能基团的化合物 ;包括含氧自由基、氧的非自由基衍生物、对氧化物、氢过氧化物、脂质过氧化物、环氧代谢物等。自由基 (freeradicals)是指能够独立存在的含一个或一个以上不成对电子的任何分子或离子。主要的含氧自由基有 :超氧阴离子自由基O÷2 、羟自由基OH和氮氧自由基如NO、NO2 ;自由基属于…     

锗—132对二甲基肼诱导小鼠结肠隐窝上皮细胞微核及凋谢的拮抗作用

本文通过观察羧乙基锗倍半氧化物对二甲基肼诱导的小鼠结肠隐窝上皮细胞微核和凋亡的影响，发现羧乙基锗倍半氧化物可降低结肠隐窝上皮细胞微核和凋谢数，并有剂量效应关系。说明羧乙基锗倍半氧化物具有明显的拮抗微核和凋谢的作用。该方法可作为抗结肠致癌物的快速筛选试验。     

Effect of metal chelators and antiinflammatory drugs on the degradation of hyaluronic acid

Degradation of hyaluronic acid (measured viscometrically) by oxygen-derived free radicals (ODFR) generated 1) by autoxidation of ferrous EDTA chelates and 2) enzymatically by xanthine oxidase and hypoxanthine (XO/HX) was studied. Degradation of hyaluronic acid by XO/HX was strongly inhibited by superoxide dismutase and catalase, whereas degradation of hyaluronic acid by autoxidation of ferrous ions was weakly inhibited by catalase and unaffected by superoxide dismutase. Both ODFR-producing systems were inhibited by hydroxyl radical scavengers, suggesting that hydroxyl radical was the proximate damaging species in both systems. Penicillamine at concentrations of 1-5 mM stimulated hyaluronic acid degradation by ferrous EDTA chelates but inhibited degradation by the XO/HX system. Higher concentrations of penicillamine and all concentrations studied (1-100 mM) of other antiinflammatory drugs (chloroquine, gold sodium thiomalate, and salicylate) inhibited hyaluronic acid degradation by both the autoxidation and enzymatic ODFR-producing systems, with inhibitory potency similar to that seen with known hydroxyl radical scavengers. Both systems serve as in vitro models of ODFR-mediated tissue damage which may occur in vivo at sites of inflammation.     

硒锗联合对氟致大鼠血清和肝肾抗氧化酶及钙镁元素变化的影响

目的研究硒锗联合作用对染氟大鼠血清、肝、肾中脂质过氧化物（MDA）水平和谷胱甘肽过氧化物酶（GSH-Px）活性及钙、镁的影响。方法给SD大鼠饮用含NaF（100mg／L）的蒸馏水90d，同时每天灌胃给予Na2seO30．1mg／kg和（或）锗-13210mg／kg。对大鼠血清、肝、肾组织中的GSH-Px活性、MDA、钙、镁水平进行测定。结果硒锗联合增加了GSH-Px活性，降低MDA水平；硒和（或）锗对氟诱导的大鼠血清、肝脏、肾脏中的钙水平降低具有明显抑制作用，硒锗联合对氟诱导的大鼠肝脏、肾脏中钙抑制作用强于单纯给予硒或锗；硒和（或）锗对氟诱导的大鼠血清、肾脏中的镁水平降低具有明显抑制作用，硒锗联合对氟诱导的大鼠肝脏的镁水平降低具有明显抑制作用。结论硒锗联合对氟毒性具有明显的拮抗作用，其机制与抗脂质过氧化作用有关；硒锗联合对氟诱导的大鼠钙镁变化的影响具有协同作用。     

The effect of linoleic and arachidonic acid derivatives on calcium transport in vesicles from cardiac sarcoplasmic reticulum

The effect of linoleic and arachidonic acid derivatives on ATP-dependent calcium transport was studied in the isolated vesicles from cardiac sarcoplasmic reticulum of guinea-pigs. Oxidation products of linoleic and arachidonic acids, obtained either by autoxidation or incubation with soybean lipoxygenase, effectively blocked in a dose-dependent manner, the net influx of calcium in the absence or presence of 5 mM of oxalate. Unoxidized fatty acids were much weaker at lower concentrations as compared to their oxidized counterparts, except the lipoxygenase-generated product of arachidonic acid which had only a marginal effect even at high concentrations. Autoxidation products of arachidonic acid were the most potent inhibitors of calcium transport. Likewise, autoxidation products of linoleic and arachidonic acids and lipoxygenase-generated products of linoleic acid induced a dose-dependent release of calcium from vesicles previously loaded with 45Ca, and release was further enhanced in the presence of 0.5 mM of EGTA. In contrast, lipoxygenase metabolites of arachidonic acid caused a transient increase in net calcium content. The effect of the fatty acid derivatives on calcium transport did not appear to be due either to the inhibition of Ca2+-ATPase activity or to a non-specific detergent-like action. The effects of oxidized fatty acids, on ATP-dependent calcium accumulation into and release from cardiac microsomal fraction were similar but less potent than those of classical calcium ionophores, X537A or A23187.     

Effects of ionic strength on the activity of superoxide dismutase in vitro

Changes in superoxide dismutase (SOD) activity were studied in vitro at increasing NaCl or KCl concentrations. SOD activity was measured using two different systems of superoxide radical generation: pyrogallol autoxidation, and xanthine-xanthine oxidase reaction. Pyrogallol autoxidation was directly measured by spectrophotometry, whereas in the second case cytochrome c reduction was followed at 550 nm. The inhibition of SOD on those parameters was taken as measure of SOD activity. Increasing concentrations of NaCl and KCI significantly increased the rate of pyrogallol autoxidation. The inhibitory effect of SOD significantly decreased under the influence of these salts and followed an exponential curve. The two salts studied resulted in essentially identical changes in SOD activity. Increasing concentrations of NaCl and KCl decreased the rate of cytochrome c reduction in the xanthine-xanthine oxidase system. When correcting the results for these primary effects, SOD activity also displayed in this system an exponential decay with increasing salt concentrations. The results are interpreted in terms of the known charge distribution pattern on the surface of the SOD molecule, and of the age-dependent increase of the intracellular potassium and sodium concentrations in the postmitotic cells.     

Mechanism of autoxidation of hemoglobin Kempsey (beta 99 Asp----Asn)

The mechanism of autoxidation of oxyhemoglobin Kempsey (beta 99 asp----asn) was studied at pH 7.0, 37 degrees C, using isoelectric focusing electrophoresis. During autoxidation, two intermediate hemoglobins, (alpha 2+ beta 3+)2 and (alpha 3+ beta 2+)2 were observed, and these were consecutively changed to methemoglobin. The autoxidation rates of oxyhemoglobin Kempsey were reduced about 43% by the addition of catalase and superoxide dismutase, but were not significantly changed by the addition of inositol hexaphosphate. This abnormal hemoglobin autoxidized more slowly than normal hemoglobin A. The differences in the autoxidation rates between these hemoglobins were explained by the changes in quaternary structure of these proteins. The reaction rate constant, k+1, k+2, k+3 and k+4 of each step including the reactions: (formula; see text) were determined by the analysis of fractional changes in these hemoglobin derivatives during the autoxidation. The difference in the reaction rate constants between k+1 and k+3 was explained by the nonequivalence of alpha and beta chains in tetrameric oxyhemoglobin Kempsey. The reaction mechanism of autoxidation of hemoglobin Kempsey was discussed on the basis of these kinetic results.     

Insulin secretion is stimulated by ethanol extract of Anemarrhena asphodeloides in isolated islet of healthy Wistar and diabetic Goto-Kakizaki Rats.

BACKGROUND: The hypoglycemic effect of extract of Anemarrhena asphodeloides has been accounted for by the substance mangiferin which increases insulin sensitivity. The present study aimed to investigate whether an ethanol extract of Anemarrhena asphodeloides would stimulate insulin secretion and if so, further elucidate the mechanism behind this effect. METHODS: Isolated pancreatic islets of normal Wistar rats and spontaneously diabetic Goto-Kakizaki (GK) rats were batch incubated or perifused to study effect of Anemarrhena asphodeloides extract (TH2) on insulin release. RESULTS: At 3.3 mM glucose, 2, 4, and 8 mg/ml TH2 increased the insulin release of Wistar rat islets 2.5-, 4.1-, and 5.7-fold, respectively (p < 0.05) and of GK rat islets 1.7-, 3.0-, and 6.3-fold, respectively (p < 0.01). Similarly at 16.7 mM glucose, 2, 4 and 8 mg/ml TH2 increased insulin release of Wistar rat islets 1.5-, 2.2-, and 3.8-fold, respectively (p < 0.05) and of GK rat 2.5-, 4.2-, and 11.9-fold, respectively (p < 0.01). In perifusions of islets, TH2 also increased insulin secretion that returned to basal levels when TH2 was omitted from the perifusate. Mangiferin had no effect on insulin secretion of islets. In islets depolarized by 30 mM KCl and B-cell K-ATP channels kept open by 0.25 mM diazoxide, TH2 (8 mg/ml) further enhanced insulin secretion at 3.3 but not at 16.7 mM glucose. Pertussis toxin suppressed the insulin stimulating effect of 2 and 8 mg/ml TH2 by 35 % and 47 % (p < 0.05 and p < 0.001, respectively). CONCLUSIONS: Ethanol extract of the roots of Anemarrhena asphodeloides contains a substance, TH2, that stimulates insulin secretion both at 3.3 and 16.7 mM glucose in islets of normal Wistar and diabetic GK rats. The mechanism behind TH2-stimulated insulin secretion involves an effect on the exocytotic machinery of the B-cell, mediated via pertussis toxin-sensitive Gi- (or Ge-) proteins.     

Hemoglobin autoxidation at physiological concentrations

Methemoglobin formation was studied at near physiological hemoglobin concentration. The reaction proceeds at a faster rate when the concentration of hemoglobin is high (15-18 mM in heme) than when it is low (2 mM). Constant shaking of hemoglobin preparations during the incubation decreases the differences seen in the rates of autoxidation between concentrated and dilute samples. When red cell hemolysate is used instead of pure hemoglobin, similar results are obtained. A comparison of rates of methemoglobin formation in hemoglobin solutions under low air pressure (1/2 atm) with those under normal air pressure (1 atm) shows no differences between concentrated and dilute samples. There is also no significant difference between the rates of autoxidation of dilute and concentrated solutions when the reactions are carried out under one atmosphere of oxygen (100 percent O2). The study of one patient with hereditary spherocytosis demonstrated higher hemoglobin autoxidation rate in spherocytes, which have higher hemoglobin concentration, than in normal biconcave red cells. These results suggest that: a) the rate of hemoglobin autoxidation at red cell hemoglobin concentration is significantly faster than rates obtained by studying dilute solutions; b) although the accelerated oxidation might be related to multiple factors, one seems to be less accessibility of oxygen when the hemoglobin solution is highly concentrated.     

Antiparasitic activity of a triphenyl tin complex against Leishmania donovani

Visceral leishmaniasis is a life-threatening human disease commonly known as kala-azar. Leishmania donovani is the causative agent of this parasitic disease transmitted by the sand fly vector to infect hosts. Triphenyl tin salicylanilide thiosemicarbazone [Ph(3)Sn(OSal.TSCZH)] (TTST) which is an organometallic complex of triphenyl tin has been evaluated to explore possibility to develop a potent chemotherapeutic agent against visceral leishmaniasis. Effect of triphenyl tin complex on growth inhibition and host--parasite interaction were examined both in vitro and in vivo. Release of toxic superoxide radical was measured spectrophotometrically through the formation of blue formazan derived from reduced nitrobluetetrazolium. To understand mode of action of Ph(3)Sn(OSal.TSCZH), superoxide dismutase activity was determined spectrophotometrically by measuring ability of this enzyme to inhibit pyrogallol autoxidation and also by activity staining of the non-denaturing polyacrylamide gels after separating superoxide dismutase. Antileishmanial activity of triphenyl tin complex were found to be effective both in vitro and in vivo at lower concentrations compared to the existing toxic drugs available. IC(50) of Ph(3)Sn(OSal.TSCZH) was calculated as 0.05+/-0.01mg/L. Intracellular survival of the parasite in host macrophages was inhibited by TTST in a dose dependent manner. Parasite burden in spleen was reduced to 87% under TTST treatment (10mg/kg body weight) and under sodium antimony gluconate (20mg/kg body weight) reduced nearly to 65%. Its action as a chemotherapeutic agent is found to be mediated through inhibition of superoxide dismutase and simultaneous release of toxic superoxide radical. We propose that Ph(3) Sn(OSal.TSCZH) may be considered as a prospective candidate to establish a better line of therapeutic process against experimental visceral leishmaniasis.     

Involvement of hydrogen peroxide and hydroxyl radical in the 'oxygen paradox': reduction of creatine kinase release by catalase, allopurinol or deferoxamine, but not by superoxide dismutase

The objective of this study was to test the hypothesis that cytotoxic oxygen metabolites participate in lytic cardiac cell damage, detected as creatine kinase release, upon reoxygenation of hypoxic, isolated buffer-perfused hearts (oxygen paradox). Perfusate additives included: superoxide dismutase (30 mg/l); catalase (2 mg/l); deferoxamine (0.5 mM); and allopurinol (1 mM). Creatine kinase release upon reoxygenation was reduced, to levels not significantly different from nonhypoxic controls, by adding either catalase, allopurinol or deferoxamine to the buffer during hypoxia. Reduced creatine kinase leakage was not accompanied by parallel preservation of ventricular function or coronary vascular resistance. Administration of catalase during hypoxia was superior to administering it only during reoxygenation. Treatment with catalase during both hypoxia and reoxygenation provided no more protection than administration only during hypoxia. The data suggest that an important component of hypoxia-induced cardiac cell damage is due primarily to hydrogen peroxide, which may then form hydroxyl radical. Superoxide anion plays an important role as a precursor of these species, but added superoxide dismutase alone did not significantly reduce creatine kinase loss. The data also suggest that damage resulting in creatine kinase release upon reoxygenation occurs during oxygen deprivation, and it is mediated in part by cytotoxic oxygen metabolites.