低糖诱导人脐静脉内皮细胞一氧化氮与活性氧变化的研究

目的观察低浓度葡萄糖对人脐静脉内皮细胞一氧化氮（NO）与活性氧（ROS）变化的影响。方法以体外培养人脐静脉内皮细胞株HUVEC-12为研究对象,将实验分为正常对照组（5.5mmol/L葡萄糖）、低糖组（2.8mmol/L葡萄糖）、无糖组（0mmol/L葡萄糖）。分别用2.8、0mmol/L葡萄糖干预HUVEC-12细胞,经过1、2、4、12h后,硝酸还原酶法测定NO产量,化学比色法测定一氧化氮合成酶（NOS）活性,Dihydroethidium荧光探针法测定细胞内ROS水平。结果与正常对照组相比,低糖组与无糖组NO水平降低（P〈0.01）,NOS活性下降（P〈0.01）,细胞内ROS水平升高（P〈0.01）,均呈剂量依赖关系。同一浓度组内随着时间的延长,内皮细胞NO水平、NOS活性进一步降低（P〈0.01）,ROS水平进一步升高（P〈0.05）,各指标都具有浓度和时间依赖性。结论低糖可导致内皮细胞功能障碍,NO水平降低,NOS活性下降,其机制可能与低糖导致内皮细胞氧化应激损伤有关。     

The roles of endogenous reactive oxygen species and nitric oxide in triptolide-induced apoptotic cell death in macrophages

Triptolide, a major active component extracted from the root of Tripterygium wilfordii Hook f, has been shown to possess potent immunosuppressive and anti-inflammatory properties. In the present report, we reported that triptolide increased the generation of reactive oxygen species (ROS) and nitric oxide (NO) and induced apoptosis of RAW 264.7 cells in a dose-dependent manner (5-25 ng/ml). The antioxidant, reduced glutathione (GSH), significantly inhibited triptolide-induced apoptosis and inhibited the degradation of Bcl-2 protein, disruption of mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, activation of caspase-3, and cleavage of poly-(ADP-ribose)-polymerase. The inducible nitric oxide synthase-specific inhibitor 1400w blocked triptolide-induced apoptosis, but did not alter mitochondria disruption and caspase-3 activation. These results, for the first time, implicated that the increased endogenous ROS and NO co-mediated triptolide-induced apoptosis in macrophages. ROS initiated triptolide-induced apoptosis by the mitochondria signal pathway, while the apoptotic cell death mediated by NO was not via mitochondria collapse and caspase-3 activation. In addition, combining mathematical calculation and computer simulation based on our conventional experimental results, we set and validated the apoptotic model and provided more dynamic processes of triptolide-induced apoptotic cascade in macrophages.     

Serum amyloid A induces reactive oxygen species (ROS) production and proliferation of fibroblast

Serum amyloid A (SAA) levels are elevated highly in acute phase response and elevated slightly and persistently in chronic diseases such as rheumatoid arthritis and diabetes. Given that fibroblasts exert profound effects on progression of inflammatory chronic diseases, the aim of this study was to investigate the response of fibroblasts to SAA. A dose-dependent increase in O(2) (-) levels was observed by treatment of fibroblasts with SAA (r = 0·99 and P ≤ 0·001). In addition, the expression of p47-phox was up-regulated by SAA (P < 0·001) and diphenyliodonium (DPI), a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, reduced the release of O(2) (-) by 50%. Also, SAA raised fibroblast proliferation (P < 0·001) and this effect was completely abolished by the addition of anti-oxidants (P < 0·001). These findings support the notion that, in chronic inflammatory sites, SAA activated fibroblast proliferation and ROS production.     

The regulation of blood perfusion in the renal cortex and medulla by reactive oxygen species and nitric oxide in the anaesthetised rat

Aims: The regulation of blood flow through the renal medulla is important in determining blood pressure, and its dysregulation in pathophysiological states, such as oxidative stress, may contribute to the development of hypertension. This investigation examined the hypothesis that reactive oxygen species has both direct and indirect actions, via scavenging NO, to determine the degree of blood perfusion through the renal medulla. Methods: Groups of male Wistar rats received a renal interstitial infusion of either tempol, a superoxide dismutase (SOD) mimetic, or tempol plus catalase (tem + cat), or diethyldithio‐carbamic acid (DETC) a SOD inhibitor, or L‐NAME alone or L‐NAME followed by DETC. Results: Medullary blood perfusion (MBP) increased by 16 ± 1% (P < 0.05) following the renal infusion of tempol and by 35 ± 4%% (P < 0.05) when tem + cat was infused. Cortical blood perfusion (CBP) was unchanged during the administration of tempol and tem + cat. The renal interstitial infusion of DETC reduced CBP by 13 ± 2%, (P < 0.05) and MBP by 22 ± 3% (P < 0.05). Infusion of L‐NAME to block NOS did not change CBP but decreased MBP by 12 ± 4%, which was (P < 0.05) less than the reduction obtained with DETC. Administration of DETC in the presence of L‐NAME reduced CBP and MBP by 17 and 14%, respectively, the latter response being approximately half that obtained when only DETC was infused. Conclusions: These findings demonstrated that both reactive oxygen species and NO determined the level of MBP. The findings support the hypothesis that reactive oxygen species can act both indirectly, via scavenging of NO, and directly via H₂O₂ to modulate blood perfusion in the medulla.     

Evaluation of the role of reactive oxygen species in male infertility

Reactive oxygen species (ROS) production from spermatozoa hasbeen measured by chemiluminescence in the two fractions of aPercoll gradient column (47 and 90%). Chemiluminescent signalswere recorded in each fraction after the addition of luminoland horse-radish peroxidase (basal state), and after stimulationwith formyl-methionyl-leucyl-phenylalanine and phorbol ester(PMA). Oligozoospermic samples show a higher rate of ROS productionthan the normozoospermic samples in both fractions of Percoll.Also, ROS were generated at a higher rate by asthenozoospermicsamples in the 90% Percoll fraction than by normal samples afterstimulation with PMA. Our data confirm the fact that white bloodcells play a major role in the production of ROS, even afterpurification on a Percoll gradient. Immunological cases werealso found to be associated with an increased production ofROS, which may be caused by the same underlying pathologicalcondition responsible for the production of the antibodies.Repeated centrifugation of the samples triggers a burst of ROSin excess of that produced after Percoll preparation. In addition,superoxide dismutase activity was found to be significantlyincreased in cases with an elevated production of ROS. It isconcluded that measuring the ROS generation by semen may yielduseful information on the functional capacity of spermatozoa,which may be used to improve the success of male infertilitymanagement.     

Human seminal plasma inhibits brain nitric oxide synthase activity

Nitric oxide is a chemical messenger which functions as a neurotransmitteror as a cytotoxic agent. Nitric oxide synthase (NOS) has beenisolated from various mammalian reproductive tissues* The presenceor absence of NOS in spermatozoa has not yet been reported.We therefore tested human and marine spermatozoa for NOS activityby measuring the conversion of argmine to citmlline. No activitywas found either in human or in murine spermatozoa. Human nativesemen and human seminal plasma exerted an inhibition on brainNOS activity, as assayed on rat brain cytosolic fractions. Thisinhibitory effect was dependent on the amount of protein presentin the human seminal plasma. No inhibitory effect was observedwhen homogenates of washed spermatozoa were tested. The humanseminal plasma did not affect the Michaelis constant (Km) ofNOS for L-arginine (endogenous NOS substrate) whereas the maximalvelocity (Vmax) was reduced, suggesting that it contains a non-competitiveinhibitor of brain NOS. This inhibitory component was virtuallyinsensitive to heat; a 10 min treatment to 95°C only slightlyreduced its ability to inhibit brain NOS. The physiologicalrelevance of our observations remains to be elucidated. Humanseminal plasma may exert an inhibition of nitric oxide synthesison cells other than spermatozoa or on cells from the male orfemale genital tract, modulating directly or indirectly (viamodulation of reactive oxygen species formation) the functionalstate of the spermatozoa.     

Erythrocytes restrict microvesicle‐induced production of reactive oxygen species by polymorphonuclear leukocytes

Microvesicles (MVs) are extracellular vesicles released by several cell types upon activation or apoptosis. MVs have the potential to activate complement, which has been suggested to mediate their clearance. However, it is not clear how complement‐opsonized MVs are prevented from activating circulating polymorphonuclear leukocytes (PMNs) with release of reactive oxygen species (ROS) and potential damage of endothelium and other bystander cells as consequence. We hypothesized that binding of opsonized MVs to erythrocytes (Es) attenuates MV‐induced PMN activation. To test this, normal PMNs were exposed to MVs in the presence and absence of Es from allogenic healthy donors. As analyzed by flow cytometry, the presence of Es restricted the PMN binding of MVs by about 85% (p = 0.002) and mediated a 60–70% inhibition of the PMN production of the ROS H₂O₂, induced by MVs, when lipopolysaccharide was used as a primer (p = 0.002). The competitive binding of MVs to Es was partly dependent on complement, since EDTA inhibited MV binding to Es by 75%. These data suggest that Es, through competitive binding, may restrict MV‐induced activation of circulating PMNs and thereby serve a role as a regulator of PMN activation.     

活性氧在宫颈癌形成中的作用

活性氧是需氧细胞在代谢过程中产生的,当活性氧累积过多时会对细胞造成伤害,产生氧化应激。机体有自身的一套抗氧化应激系统,保护细胞免受损伤。随着活性氧研究的不断深入,它在肿瘤发生发展过程中的重要作用已被证实,体内活性氧与抗氧化应激系统的失衡是肿瘤形成的关键因素。宫颈癌作为一种妇科常见的恶性肿瘤,其形成机制尚不明了。近年来,活性氧在宫颈癌形成中的临床研究和体外研究成为国内外学者探讨的热点。       

Long-lasting genomic instability following arsenite exposure in mammalian cells: the role of reactive oxygen species

Previously, we reported that the progeny of mammalian cells, which has been exposed to sodium arsenite for two cell cycles, exhibited chromosomal instability and concurrent DNA hypomethylation, when they were subsequently investigated after two months of subculturing (about 120 cell generations) in arsenite-free medium. In this work, we continued our investigations of the long-lasting arsenite-induced genomic instability by analyzing additional endpoints at several time points during the cell expanded growth. In addition to the progressive increase of aneuploid cells, we also noted micronucleated and multinucleated cells that continued to accumulate up to the 50th cell generation, as well as dicentric chromosomes and/or telomeric associations and other complex chromosome rearrangements that began to appear much later, at the 90th cell generation following arsenite exposure. The increasing genomic instability was further characterized by an increased frequency of spontaneous mutations. Furthermore, the long-lasting genomic instability was related to elevated levels of reactive oxygen species (ROS), which at the 50th cell generation appeared higher than in stable parental cells. To gain additional insight into the continuing genomic instability, we examined several individual clones isolated at different time points from the growing cell population. Chromosomally and morphologically unstable cell clones, the number of which increased with the expanded growth, were also present at early phases of growth without arsenite. All genomically unstable clones exhibited higher ROS levels than untreated cells suggesting that oxidative stress is an important factor for the progression of genomic instability induced by arsenite.     

活性氧在脊髓损伤中的作用

脊髓损伤(spinal cord injury，SCI)治疗的实验性研究在18世纪就已经开始，研究者发现兴奋性毒性、Ca2+超载、神经元凋亡与氧化应激参与了神经损伤病理过程。近期研究中活性氧学说在脊髓损伤中的作用越来越受到研究者的重视，并有研究表明线粒体呼吸链、炎症反应中的呼吸爆发等多种途径参与了SCI后活性氧生成。本文在阐述活性氧生物学作用的同时，并结合近年来以活性氧为靶点的SCI治疗策略做一小结。     

Reactive oxygen and nitrogen species in normal physiological processes

Reactive oxygen species (ROS) and reactive nitrogen species have generally been considered as being highly reactive and cytotoxic molecules. Besides their noxious effects, ROS participate in physiological processes in a carefully regulated manner. By way of example, microbicidal ROS are produced in professional phagocytes, ROS function as short-lived messengers having a role in signal transduction and, among other processes, participate in the synthesis of the iodothyronine hormones, reproduction, apoptosis and necrosis. Because of their ability to mediate a crosstalk between key molecules, their role might be dual (at least in some cases). The levels of ROS increase from a certain age, being associated with various diseases typical of senescence. The aim of this review is to summarize the recent findings on the physiological role of ROS. Other issues addressed are an increase in ROS levels during ageing, and the possibility of the physiological nature of this process.     

Generation of reactive oxygen species by mitochondria in senescence-accelerated OXYS rats

Chemiluminescence assay showed that oxygen reduction and production of superoxide anion and hydrogen peroxide by liver mitochondria in OXYS rats highly sensitive to oxidative stress were less intensive than in Wistar rats. Experiments with cytochrome c oxidase inhibitors showed that decreased O₂ ^- generation in mitochondria of OXYS rats is probably associated with changes in complex III of the electron transport chain.     

Localization of nitric oxide synthase in human trophoblast cells: role of nitric oxide in trophoblast proliferation and differentiation

PROBLEM: There are conflicting reports about the isoform of nitric oxide synthase (NOS) present in trophoblast cells. In this study, we have examined the presence of different NOS isoforms in trophoblast cells. In addition, the role of nitric oxide (NO) in trophoblast function has also been studied by investigating the possible role of nitric oxide in trophoblast proliferation and differentiation. METHOD OF STUDY: NOS isoforms in primary-term trophoblast and JEG-3 cells were identified by immunocytochemistry. The intracellular localization of this enzyme was determined by confocal laser scanning microscopy. Trophoblast proliferation was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasolium bromide (MTT) conversion assay and cellular differentiation was monitored by human chorionic gonodotropin (hCG) and progesterone secretion, measured by radioimmunoassay. RESULTS: The immunoreactive NOS was present in human trophoblast cells of normal term placenta and JEG-3 cells (a choriocarcinoma cell line) maintained in culture. Nicotinamide adenine dinucleotide phosphate (NADPH)-dependent diaphorase activity overlapped with the immunostaining of NOS. Specific antibodies against the different isoforms of NOS detected the presence of neuronal-type NOS (nNOS) only. The other two isoforms, i.e., eNOS (endothelial) and iNOS (macrophage specific) were completely absent. The nNOS was localized in cell cytoplasm. In culture, JEG-3 cells normally undergo proliferation and cytotrophoblast cells in primary culture differentiate to form hormone-secreting syncytial cells. Sodium nitroprusside (SNP), a nitric oxide donor, when added to the culture, significantly increased proliferation of JEG-3 cells and inhibited the differentiation of cytotrophoblast cells. The arrest by SNP in the formation of syncytial cells was further evidenced by the low secretion profile of hCG and progesterone. CONCLUSIONS: Our findings suggest for the first time the presence of nNOS in the human trophoblast cells and a previously unrecognized role of NO in trophoblast proliferation and differentiation.     

活性氧与肾纤维化的研究进展

肾纤维化是各种慢性肾疾病进行性发展的主要病理基础,活性氧在肾纤维化的发生和发展中扮演着重要的角色。有关抗氧化治疗肾纤维化的研究较多,N-乙酰半胱氨酸、血管紧张素转换酶抑制剂、氟非尼酮、维生素E等被认为有一定的肾保护作用,这也为肾纤维化的临床防治提供新的研究方向和治疗靶点。     

Dexamethasone inhibits apoptosis of human neutrophils induced by reactive oxygen species

Neutrophils are completely differentiated cells that die in tissues a few days after they migrate from the vascular compartment as a consequence of a rigouous apoptotic program. Many of the mediators produced during an inflammatory response delay neutrophil apoptosis allowing a more efficient removal of microorganisms but also favoring the tissue damage by reactive oxygen species (ROS) and lysosomal proteins released by neutrophils. Glucocorticoids delay the apoptosis of neutrophils but the mechanisms are not completely understood. To investigate the inhibition of glucocorticoids on neutrophil apoptosis we have used the glucose/glucose oxidase (G/GO) system as a constant source of hydrogen peroxide. When neutrophils are incubated in the presence of the G/GO system, a significant acceleration of their apoptotic response is observed. Preincubation with 10^–6 M, 10^–7 M, 10^–8 M or 10^–9 M of dexamethasone, negatively modulated the spontaneous and G/GO induced apoptosis of neutrophils. Then the G/GO system is a useful model to simulate the oxidative stress of neutrophils, and that the effect of DXM on neutrophil apoptosis depends, at least in part, on blocking the proapoptotic effect of ROS.     

一氧化氮在巨噬细胞的细胞毒效应中的作用

目的:探讨一氧化氮(NO)对巨噬细胞细胞毒效应的影响。方法:将20只昆明种小鼠分为两组,一组皮下接种S180横纹肌肉瘤细胞,另一组作为正常对照组。分别取两组小鼠腹腔灌洗液中的巨噬细胞与K562肿瘤细胞共同培养,检测在培养液中加入左旋精氨酸(L-Arg)和G-单甲基左旋精氨酸(L-NAME)后巨噬细胞杀伤率的改变。结果:正常小鼠腹腔灌洗液中的巨噬细胞在L-Arg和L-NAME存在的情况下细胞毒效应没有改变;荷瘤小鼠腹腔灌洗液中的巨噬细胞在L-Arg组和空白组中的细胞毒效应明显增强。结论:NO是巨噬细胞细胞毒作用的一个效应分子。     

Oxidative stress and nitric oxide synthase in skeletal muscles of rats with post‐infarction,compensated chronic heart failure

Aim: Involvement of oxidative stress and nitric oxide synthase (NOS) isoforms in skeletal muscle cellular adaptations to chronic heart failure (CHF) is controversial, and possible muscle fibre‐type heterogeneity in the oxidative stress and NOS responses to CHF have not been examined. Consequently, we hypothesized that the changes in determinants of elevated oxidative and nitrosylative stress associated with CHF would occur in skeletal muscle and would be similar in predominantly type I slow twitch muscle (soleus) and type II fast twitch muscle (plantaris) of rats. Methods: The purpose of this study was to measure NOS isoforms (endothelial, inducible and neuronal NOS) and antioxidant enzymes (SOD‐1, SOD‐2, catalase) by protein immunoblot as well as markers of oxidative stress by biochemical assays in soleus and plantaris muscle sections of the rat hind limb. This was performed for control and post‐infarction, compensated CHF rats. Results: Twelve weeks after coronary artery ligation‐induced moderate CHF, soleus exhibited decreased SOD‐1, SOD‐2 and eNOS, but increased iNOS and nNOS isoforms assessed by immunoblot. This was associated with elevated lipid and DNA oxidative damage assessed by biochemical assays. In contrast, plantaris muscle exhibited no changes in antioxidant enzymes or NOS isoforms, and had lower lipid and DNA oxidative damage. Conclusion: These observations suggest a heretofore unreported muscle fibre‐type‐specific response of oxidative stress and NOS isoforms to CHF is of importance in understanding the cellular mechanisms of skeletal muscle dysfunction in CHF.     

Iron-induced tissue damage and cancer: The role of reactive oxygen species-free radicals

Oxygen is poisonous, but we cannot live without It. The high oxidizing potential of oxygen molecules (dioxygen) Is a valuable source of energy for the organism and its reactivity is low; that is, spin forbidden. However, the dioxygen itself is a 'free radical' and, especially in the presence of transition metals, K is a major promoter of radical reactions in the cell. Humans survive only by virtue of their elaborate defense mechanisms against oxygen toxicity.
Iron is the most abundant transition metal in the human body- Because iron shows wide variation in redox potential with different co-ordination ligands, it may be used as a redox intermediate in many biological mechanisms. However, it is precisely this redox activeness that makes iron a key participant in free radical production.
The current research on the relationship between iron and cancer is briefly reviewed. Research results are reported here which indicate that iron, when bound to certain ligands, can cause free-radical mediated tissue damage and become carcinogenic. The present study also suggests that iron may also have a significant role in spontaneous human cancer.