Ex vivo study for the assessment of behavioral factor and gene polymorphisms in individual susceptibility to oxidative DNA damage metals-induced

Transition metals in fine particulate matter generated by combustion induce oxidative DNA damage and inflammation. However, there is remarkable inter-individual variability in susceptibility to these damages. To assess this variability, an ex vivo study was performed using lymphocytes of 47 Caucasian healthy subjects. Cell samples were exposed to a water solution of oil fly ash (OFA). This was formed by the distinctive transition metals vanadium, iron, and nickel. Oxidative DNA damage was evaluated by testing cell viability, intracellular ROS production and 8-oxo-dG. DNA fragmentation and DNA repair capacity were assessed by using the Alkaline-Halo assay. GSTM1, GSTT1, hOGG1, and C677T and A1298C MTHFR gene polymorphisms were tested. Demographic and behavioral factors, collected by questionnaire, were also considered. OFA induced damages showed: (a) a 20-fold variation in range among different subjects in ROS production, (b) a 7-fold variation in range of 8-oxo-dG, and (c) a 25-fold variation in range in DNA repair capacity. A significant increase in DNA damage was detected in GSTT1-deficent subjects compared with wild type genotype carriers. Increases in cytoplasmic ROS and decreases in DNA repair capacity (P<0.05) were observed in C677T and A1298C variants of MTHFR. A remarkable protective effect of high fruits and vegetable intake was observed for ROS production and DNA damage. Conversely, an adverse effect of meat intake was observed on ROS increase, DNA damage and repair capacity, probably due to the increased intake of bioavailable iron. Smoking decreased DNA repair capacity, while age increased OFA-induced DNA damage. The wide comparative analysis of the complex interactions network, between genetic and behavioral factors provides evidence of the remarkable role of several lifestyle factors. In comparison to genetic polymorphisms they seem to have a higher weight in determining individual susceptibility to the adverse effects of airborne pollutants as transition metals.     

Recovery of human lymphocytes from oxidative DNA damage; the apparent enhancement of DNA repair by carotenoids is probably simply an antioxidant effect

Summary Background: Many epidemiological studies have identified a protection against cancer associated with consumption of fruit and vegetables. One factor is this protection may be the enhancement of cellular DNA repair activity by micronutrients, such as carotenoids, found in these foods. Aims of the study: To measure the capacity of lymphocytes isolated from volunteers supplemented with β-carotene, lutein or lycopene to recover from DNA damage induced in vivo by treatment with H₂O₂. Methods: Healthy volunteers were given supplements of lutein (15 mg/day), lycopene (15 mg/day) and βcarotene (15 mg/day), each for 1 week, the supplementation periods being separated by 3-week wash-out periods. Blood samples were taken at the beginning and end of each supplementation, and at 1 week and 3 weeks during the wash-out period. Carotenoid levels were measured in plasma. Lymphocytes were isolated and frozen. Subsequently, they were treated with 100 μM H₂O₂ and incubated for up to 24 h; DNA damage was measured with the comet assay (single cell gel electrophoresis) after 0, 2, 4, 8, and 24 h. Results: Increases of 2- to 3-fold in mean plasma lutein and β-carotene concentrations were seen at the end of the respective supplementation periods; they returned virtually to basal levels after wash-out. Lycopene concentrations were less affected by supplementation, and were more variable. H₂O₂-induced DNA strand breaks were apparently only slowly rejoined by the lymphocytes. The rejoining of breaks in the first few hours appeared substantially faster in lymphocytes following supplementation with β-carotene, but no such effect was seen with lutein. In those individuals who showed increases in lycopene concentrations, the recovery was significantly faster. Lymphocytes that were not treated with H₂O₂ showed a transient increase in DNA breakage to about double the background level in 2 h, presumably as a result of exposure to atmospheric oxygen; this effect, too, was relieved by supplementation with lycopene or β-carotene. Conclusions: While certain carotenoids appear to enhance recovery from oxidative damage, this is probably in fact an antioxidant protective effect against additional damage induced by atmospheric oxygen, rather than a stimulation of DNA repair. Received: 6 December 1999, Accepted: 22 March 2000     

Protective effects of broccoli (Brassica oleracea) against oxidative damage in vitro and in vivo

The antioxidative effect and protective potential against diabetes of the broccoli flower were investigated both in vitro and in a diabetic rat model. Among fractions of MeOH, CH2Cl2, BuOH, and H2O, the BuOH fraction exerted the strongest inhibitory activities on 1,1-diphenyl-2-picrylhydrazyl radical, radical-induced protein oxidation, and nitric oxide generation by sodium nitroprusside. The in vitro results suggest that the BuOH fraction from the broccoli flower has a protective potential against oxidative stress. The rat model with diabetes induced by streptozotocin was employed to evaluate the protective effect of the BuOH fraction in vivo. Diabetic rats showed reduced body weight gain and heavier kidney and liver weights than normal rats, while oral administration of the BuOH fraction at an oral dose of 100 or 200 mg/kg body weight/d for 20 d attenuated the physiological changes induced by diabetes. In addition, oral administration of the BuOH fraction to diabetic rats led to significant decreases in serum glucose and glycosylated protein, while it resulted in the increase of serum albumin, implying that the BuOH fraction improves the abnormal metabolism of glucose and protein that leads to oxidative stress. Moreover, it significantly reduced thiobarbituric acid-reactive substance levels in serum, hepatic and renal mitochondria. This suggests that the BuOH fraction would alleviate the oxidative stress associated with diabetes through the inhibition of lipid peroxidation. The present study demonstrates that the BuOH fraction has an antioxidative effect in vitro and it protects against oxidative stress induced by diabetes in an in vivo model.     

Lignin-stimulated reduction of oxidative DNA lesions in testicular cells and lymphocytes of sprague-dawley rats in vitro and ex vivo

Lignin biopolymers constitute 30% of plant biomass and belong to the most abundant organic polymers on earth. We showed previously that this important component of dietary fiber exhibited a protective effect against the overall DNA damage induced by H2O2 or N-methyl-N'-nitro-N-nitrosoguanidine in hamster lung cells and human foreskin cells cultured in vitro. The objective of the present work was to examine DNA-protective effects of lignin in rat testicular cells and rat peripheral blood lymphocytes using in vitro and ex vivo experiments. H2O2 and visible light-excited methylene blue (MB) were used as DNA-damaging agents. Testicular cells were chosen because the germinal epithelium of testes is one of the most proliferately active tissues potentially susceptible to DNA-damaging effects. As a second target peripheral blood lymphocytes were chosen because dietary lignin or its metabolites circulate in the animal organism probably through the blood system. For the in vitro experiments, isolated cells were preincubated with lignin for 2 h before treatment with one of the oxidative agents. In ex vivo experiments, the cells were exposed to H2O2 or visible light-excited MB after isolation from rats fed either a common diet or a lignin-supplemented diet. The water-soluble, sulfur-free lignin used in experiments was obtained by fractionation of hardwood hydrolysate. The level of direct single-strand DNA breaks in H2O2-treated cells was measured by the classical comet assay, and the level of oxidative DNA lesions in visible light-treated cells was measured by a modified comet assay. We found that lignin reduced DNA lesions induced by H2O2 or visible light-excited MB both in vitro and ex vivo. The major conclusion of our study is that lignin polymer obtained by fractionation of hardwood hydrolysate manifested a specific type of antimutagenic effect.     

Evidence that dietary supplementation with carotenoids and carotenoid-rich foods modulates the DNA damage: repair balance in human lymphocytes

Epidemiological evidence has shown that the habitual consumption of diets high in fruits and vegetables is associated with reduced risk of cancers. The challenge is to identify causal mechanisms of effect. The aim of the current study was to determine whether an increase in rate of removal of DNA single-strand breaks (SSB) following oxidative challenge could be provoked ex vivo in peripheral blood lymphocytes (PBL). The PBL were isolated from apparently healthy volunteers following dietary intervention with: (1) a mixed carotene capsule; (2) a daily portion of cooked minced carrots; (3) a matched placebo; (4) a portion of mandarin oranges; (5) vitamin C tablets. Single-cell gel electrophoresis was employed to measure baseline levels of SSB and DNA susceptibility to oxidative damage, and to monitor the number of SSB over 4 h, in both unchallenged and H2O2-treated PBL. The enzymatic capacity for repair of different types of DNA oxidative lesions was also measured using two related cell-free assays. There was no evidence that any of the dietary supplementation regimens altered baseline levels of SSB, provided any direct antioxidant protection or altered DNA repair capacity, with two exceptions: the number of SSB following exposure to H2O2 decreased more rapidly in PBL from volunteers given the mixed carotene capsules and repair patch synthesis activity in PBL increased from volunteers given the cooked carrots. These results suggest that carotenoids and carotenoid-rich foods can influence DNA damage:repair by modulation of discrete stages in the DNA repair mechanisms.     

Kiwifruit protects against oxidative DNA damage in human cells and in vitro

Antioxidant micronutrients may account for the beneficial effects of fruits on human health. A direct demonstration that consumption of fruit decreases oxidative DNA damage in human cells would support this hypothesis. Kiwifruit was taken as an example of a food with putative antioxidant properties, and its effectiveness at decreasing oxidative DNA damage was assessed in ex vivo as well as in vitro tests. The comet assay (single-cell gel electrophoresis) was used to measure DNA damage in lymphocytes collected during a human supplementation trial with a single 0.5-liter drink of kiwifruit juice (with water as a control). The comet assay was also modified to assess the antioxidant effect of kiwifruit in vitro by measuring the ability of an extract to interfere with oxidative damage to DNA induced by H2O2. Ex vivo, consumption of kiwifruit led to an increased resistance of DNA to oxidative damage induced by H2O2 in isolated lymphocytes, in comparison with lymphocytes collected after a control drink of water. No effect was seen on endogenous DNA damage. In vitro, a simple extract of kiwifruit, buffered to pH 7, was more effective than a solution of vitamin C (of equivalent concentration) at protecting DNA from damage, whereas at the highest concentrations tested, neither kiwi extract nor vitamin C had a protective effect. We have demonstrated significant antioxidant activity of kiwifruit ex vivo and in vitro, not attributable entirely to the vitamin C content of the fruit. Our dual approach is appropriate for testing other fruit and vegetable products for potential antioxidant effects.     

The effects of taurine on permethrininduced cytogenetic and oxidative damage in cultured human lymphocytes

Permethrin (PM) is a common pyrethroid pesticide used to control pests in agriculture, forestry, horticulture, health care, homes, and textile industry. It is confirmed as a strong mutagen in animals and humans. Taurine (TA) is an amino acid found in mammalian tissues that protects the cell against DNA damage. In this study, we investigated whether supplementation of human lymphocyte cultures with TA (in the concentrations of 25 μg mL-1, 50 μg mL-1 and 100 μg mL-1) provided any protection against PM toxicity applied in the concentration of 200 μg mL-1. Genotoxicity was assessed using the micronucleus (MN) and sister chromatid exchanges (SCE) tests. In addition, we measured the total antioxidant capacity (TAC) and total oxidative stress (TOS) levels in the plasma to determine oxidative effects. PM increased SCE and MN levels and altered TAC and TOS levels. TA alone did not affect SCE and MN levels compared to controls, regardless of the concentration applied. In addition, it increased TAC levels without changing TOS levels. Moreover, it significantly buffered the negative cytogenetic and oxidative effects induced by PM in a clear dose-dependent manner. In conclusion, this study is the first to evidence the beneficial effects of TA against PM-induced DNA and oxidative damages in vitro.     

Exposure to traffic exhausts and oxidative DNA damage

Aims: To assess the relations between exposure to traffic exhausts and indicators of oxidative DNA damage among highway toll station workers.

Methods: Cross-sectional study of 47 female highway toll station workers exposed to traffic exhausts and 27 female office workers as a reference group. Exposure assessment was based on average and cumulative traffic density and a biomarker of exposure, urinary 1-hydroxypyrene-glucuronide (1-OHPG). Urinary 8-hydroxydeoxyguanosine (8-OHdG) was used as a biomarker of oxidative DNA damage. Plasma nitric oxide (NO) was measured as an indicator of oxidative stress related to traffic exhaust exposure.

Results: The mean concentration of urinary 8-OHdG was substantially higher among the exposed non-smokers (13.6 µg/g creatinine) compared with the reference non-smokers (7.3 µg/g creatinine; difference 6.3, 95% CI 3.0 to 9.6). The mean concentration of NO among the exposed (48.0 µmol/l) was also higher compared with the reference non-smokers (37.6 µmol/l; difference 10.4, 95% CI –0.4 to 21.2). In linear regression adjusting for confounding, a change in log(8-OHdG) was statistically significantly related to a unit change in log(1-OHPG) (ß = 0.372, 95% CI 0.081 to 0.663).

Conclusions: Results indicate that exposure to traffic exhausts increases oxidative DNA damage. Urinary 8-OHdG is a promising biomarker of traffic exhaust induced oxidative stress.

     

甲基叔丁基醚致DNA损伤的体内和体外研究

目的 探讨甲基叔丁基醚（MTBE）对动物致癌的机制.方法 小鼠经呼吸道染毒MTBE 20 d后,取肝、肾、肺细胞进行单细胞凝胶电泳（SCGE）、DNA交联试验及肺和肾组织中丙二醛（MDA）含量测定.对体外培养的大鼠肺Ⅱ型细胞、肝细胞进行SCGE、DNA交联试验和程序外DNA合成试验（LDS）.结果 MTBE 1 440、4 968 mg/m^3组染毒小鼠肝细胞、各剂量组肾细胞、4 968 mg/m^3组肺细胞DNA迁移距离均大于阴性对照组;肝细胞DNA迁移距离与MTBE浓度有剂量-反应关系（r=0.997,P=0.003）.MTBE1 440、4 968 mg/m^3组雌性小鼠及4 968 mg/m3组雄性小鼠肾MDA含量高于阴性对照组,差异有统计学意义（P＜0.05）.MTBE浓度＞0.050mmol/L时,大鼠肺Ⅱ型细胞、肝细胞DNA迁移距离较阴性对照组增加,差异有统计学意义（P＜0.05）,且DNA迁移距离与MTBE浓度有剂量-反应关系（r肺=0.967,T肝=0.963,均P＜0.05）;5.0、10.0 mmol/L MTBE组大鼠肺Ⅱ型细胞、肝细胞的3H-TrR掺入量每分钟脉冲数（CPM）均高于阴性对照组,差异有统计学意义（P＜0.05）;各剂量组小鼠肝细胞、大鼠肺Ⅱ型细胞和肝细胞的DNA交联率与阴性对照组的差异均无统计学意义（P＞0.05）.结论 MTBE对DNA有损伤作用,细胞DNA断裂和脂质过氧化是其引起动物肝、肾肿瘤的可能机制之一.     

Prevention of oxidative DNA damage in inner organs and lymphocytes of rats by green tea extract

Background

Consumption of green tea (GT) is associated with decreased incidences of specific forms of cancer in humans and it was postulated that its antioxidant (AO) properties may account for these effects. The evidence for AO effects of GT is mainly based on the results from in vitro experiments and on animal studies in which protection against chemically induced damage was monitored.

Aim of the study

The goal of the study was the investigation of the prevention of strand breaks and DNA migration attributable to endogenous oxidation of bases by GT extract (GTE) in inner organs and lymphocytes of untreated rats. In addition, immunological parameters and biochemical markers were monitored.

Methods

DNA migration was measured in hepatocytes, colonocytes and lymphocytes after consumption of a low (1.3 mg/kg bw per day, 5 days) and a high dose (6.5 mg/kg bw per day, 5 days) of GTE in COMET assays (n = 5 animals per group). In addition, immunological parameters (TNF-α, IFN-γ, IL-4 and IL-10), the total AO capacity and oxidized low-density lipoproteins were determined in plasma.

Results

No evidence for reduction in DNA damage was found with a lower dose, whereas with the higher dose, reduction in DNA migration attributable to formamidopyrimidine-DNA-glycosylase sensitive lesions (oxidized purines) and endonuclease III-sensitive sites (oxidized pyrimidines) (58 and 73%) was observed in lymphocytes; also, in colonocytes (reduction in FPG-sensitive sites by 46%) and hepatocytes (decrease in Endo III-sensitive sites by 74%) protective effects were found, while none of the other parameters was altered.

Conclusions

Our results show that a dose of GTE, which is equivalent to consumption of 500 ml GT/p/day in humans protects lymphocytes and to a lesser extent inner organs against oxidative DNA damage, while no effect was seen with a lower dose corresponding to an uptake of 100 ml/p/day.     

砷对人淋巴细胞 DNA 氧化损伤的作用

目的：探讨砷（As)引起植物血凝集素（PHA）刺激和无刺激人外周血淋巴细胞DNA氧化性损伤。方法：用10μmol/L砷处理细胞2h,经单细胞凝胶电泳（SCGE,或彗星试验）－FPG（甲酰胺基嘧啶－DNA糖基化酶）消化法检测砷引起的DNA碱基损伤。结果：砷引起的DNA链断裂的修复过程与过氧化氢（H2O2）引起的修复过程类似,FPG消化产生的单链断裂,或砷引起的碱基损伤在PHA刺激淋巴细胞较未刺激细胞显著,在PHA刺激的淋巴细胞,砷和H2O2引起的DNA链断裂2h分别修复63％和68％,但在未刺激细胞分别修复大约34％和43％,在PHA刺激的淋巴细胞,砷和H2O2引起的碱基损伤2h分别修复40％和49％,但在未刺激细胞分别修复大约19％和21％。结果：微量砷可引起人类细胞DNA氧化性损伤,损伤的碱基主要是嘌呤或甲酰胺基嘧啶,未分裂（刺激）淋巴细胞修复砷与H2O2引起的DNA损伤较慢。     

Personal exposure to ultrafine particles and oxidative DNA damage

Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable instruments in six 18-hr periods in 15 healthy nonsmoking subjects. Exposure contrasts of outdoor pollution were achieved by bicycling in traffic for 5 days and in the laboratory for 1 day. Oxidative DNA damage was assessed as strand breaks and oxidized purines in mononuclear cells isolated from venous blood the morning after exposure measurement. Cumulated outdoor and cumulated indoor exposures to UFPs each were independent significant predictors of the level of purine oxidation in DNA but not of strand breaks. Ambient air concentrations of particulate matter with an aerodynamic diameter of < or = 10 microm (PM10), nitrous oxide, nitrogen dioxide, carbon monoxide, and/or number concentration of UFPs at urban background or busy street monitoring stations was not a significant predictor of DNA damage, although personal UFP exposure was correlated with urban background concentrations of CO and NO2, particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution.     

The effects of 1-nitropyrene on oxidative DNA damage and expression of DNA repair enzymes

Nitropyrenes (NPs) present in diesel and gasoline emissions are mutagenic and carcinogenic in experimental animals. Nitro-reduction of 1-NP causes oxidative stress. It is unclear whether 8-hydroxydeoxyguanosine (8-OH-dG) is produced from 1-NP and whether it contributes to the carcinogenic activity of 1-NP. In this study, we measured the level of reactive oxygen species (ROS) in cultured human lung epithelial cells after exposure to 1-NP and the intracellular level of 8-OH-dG and expression level of the 8-OH-dG repair enzymes. As results, 1-NP induced the generation of 8-OH-dG via ROS, but 8-OH-dG repair enzymes prevented an increase of 8-OH-dG formation in cellular DNA of the A549 cell line below 250 microM of 1-NP. These data suggest that 1-NP can induce oxidative DNA damage by generation of ROS, which may play a role in the carcinogenesis induced by 1-NP. These data also suggest that individuals with impaired DNA repair enzymes might be more susceptible to lung cancer induced by 1-NP.     

Alcohol consumption and oxidative DNA damage

To examine the effects of alcohol consumption on cancer risk, we measured oxidative DNA damage and its repair activity in the livers and esophagi of rats fed with ethanol. Using our previously designed protocol for feeding rats with a high concentration of ethanol, we examined the effects of ethanol consumption on 8-oxo-Gua generation and repair activity in the livers and esophagi of rats. We found that a high concentration of ethanol accompanied with a vitamin-depleted diet increased 8-oxo-Gua and its repair activity. 8-Oxo-Gua is known to induce point mutations, leading to carcinogenesis. Therefore, these results suggested that a high concentration of ethanol and an irregular diet increased liver and esophageal cancer risk. On the other hand, we showed that a low concentration of ethanol decreased 8-oxo-Gua and its repair activity in the livers of mice treated with a carcinogen. Taken together, the effects of ethanol consumption on cancer risk depend on the ethanol concentration and the diet pattern.     

Detection of DNA damage in stimulated human lymphocytes after enflurane exposure in vitro.

DNA damage was detected by nucleoid sedimentation in human lymphocytes stimulated with pokeweed mitogen after exposure to enflurane. Enflurane induces DNA damage at an exposure concentration of 0.2 vol%. Higher enflurane concentrations increase the rate of DNA damage. The DNA damage seen after exposure to enflurane concentrations of 0.2 and 3.0% vol is comparable to damage after X-radiation of 0.1 and 0.7 Gy. DNA single-strand breaks can be demonstrated by nucleoid sedimentation and can indicate damage before DNA repair begins. Therefore, detected DNA single-strand breaks may be reversible. However, DNA repair is not always successful and an increased number of DNA single-strand breaks could lead to irreversible DNA damage. The method of nucleoid sedimentation helps to show DNA damage in proliferating cells after exposure to volatile anesthetics or therapeutic gases.     

精子DNA损伤对体外受精胚胎移植的影响

目的 探讨不育男性患者其精子DNA损伤对体外受精-胚胎移植(IVF-ET)的胚胎质量及临床结局的影响.方法 回顾性分析了在乌鲁木齐市妇幼保健院生殖中心行常规体外受精(IVF)和卵胞浆内单精子显微注射(ICSI)治疗的不孕夫妇,共计125例.按照精子DNA碎片指数(DFI)＜15％、15％～30％、＞30％为正常组、低损...     

Protective effects of Asparagus racemosus on oxidative damage in isoniazid-induced hepatotoxic rats: an in vivo study

To investigate the hepatoprotective activity of Asparagus racemosus against isoniazid-induced hepatotoxicity in male albino rats. Rats (n = 6 per group)were divided into four groups: saline-treated control, saline-treated control with A. racemosus extract (50 mg/kg), isoniazid treatment alone (100 mg/kg, intraperitoneal [i.p.]), and isoniazid-A. racemosus extract (50 mg/kg)administered orally as cotreatment. Animals were treated for 21 days and euthanized 1 h after the last drug administration. Evaluated body weight, serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, g-glutamyl transferase, total protein, albumin, hepatic malondialdehyde content, superoxide dismutase, catalase, cytochrome P450 2E1 (CYP2E1)activity and glutathione (GSH). A. racemosus extract prevented isoniazid-induced hepatotoxicity, indicated by both diagnostic indicators of liver damage, liver functional profile, significantly (p < 0.05)inhibited CYP2E1 activity, markedly attenuated oxidative stress by improved enzymatic, non-enzymatic antioxidants levels and mitigate malondialdehyde, lipid hydroperoxide significantly (p < 0.05). These results suggest that A. racemosus extract exerts its hepatoprotective activity by inhibiting the production of free radicals and acts as a scavenger, reducing the free radical generation via inhibition of hepatic CYP2E1 activity, increasing the removal of free radicals through the induction of antioxidant enzymes and improving non-enzymatic thiol antioxidant GSH.     

二甲基甲酰胺致心肌细胞氧化损伤的体外实验研究

目的 探讨二甲基甲酰胺(dimethylformamide,DMF)对小鼠心肌细胞(H9c2)的氧化损伤作用及维生素C(vitamin C,VitC)的保护效应.方法 使用不同剂量梯度DMF作用心肌细胞24 h、48 h、72 h,同时分别用含有DMF(100 mM)和0.025 mM、0.050 mM、0.100 mM、0.250 mM的VitC培养液培养心肌细胞24 h、48 h、72 h,采用试剂盒测定细胞内超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽(glutathione,GSH)、丙二醛(malondialdehyde,MDA)的含量以观察细胞氧化应激状态和VitC的保护效应.结果 不同浓度的DMF分别作用于心肌细胞24h、48 h和72 h后使SOD和GSH含量降低,MDA含量升高,产生了明显脂质过氧化并呈现一定的剂量-时间效应关系.保护组VitC在低浓度(0.025 mM、0.050 mM、0.100 mM)时对DMF对心肌细胞的氧化损伤具有保护作用,使SOD和GSH含量升高,MDA降低.保护组VitC在高浓度(0.250 mM)时反而加重DMF对心肌细胞的氧化损伤.结论 二甲基甲酰胺(DMF)对小鼠心肌细胞细胞(H9c2)产生了明显的氧化损伤,从而证实DMF所致的氧化应激是其引起细胞毒性的重要机制.小剂量VitC对DMF致心肌细胞的氧化损伤具有明显的保护作用.     

线粒体DNA氧化损伤机制的探讨

线粒体中呼吸链产生的自由基是体内自由基主要来源。在一定的生理（如年老）或／和病理条件下,自由基可以突破人体防御机制,损伤机体。由于线粒体ＤＮＡ（ｍｉｔｏｃｈｏｎｄｒｉａｌ ＤＮＡ,ｍｔＤＮＡ）结构功能特殊性,导致其成为自由基攻击的最主要最脆弱的靶目标,从而引起线粒体功能障碍,最终造成细胞的衰老与死亡。在此将探讨ｍＴＤＮＡ氧化损伤的形成、防御及修复机制。     

Chromosome and oxidative damage biomarkers in lymphocytes of Parkinson's disease patients.

As cancer development usually results from exposure to several environmental risk factors in interaction with the genetic susceptibility of the host, it could be of interest to investigate if neurodegeneration, as occurs in Parkinson's disease (PD) patients can be attributed at least partially, to environmental risk factors. There is growing evidence that oxidative stress could play a significant role as a risk factor in the aetiology and pathogenesis of neurodegenerative diseases, emphasising the need for new individual and human-based approaches. The aim of our research is to explore the relation between chromosome instability and oxidative stress biomarkers in Parkinson's disease using a variety of strategies. We determined peripheral markers for oxidative damage in PD by testing for spontaneous and induced chromosomal damage, DNA strand breaks, oxidised pyrimidines and altered purines both in peripheral blood and cultured lymphocytes. We also measured glutathione S-transferase activity in the plasma of patients and controls. Compared to healthy controls, PD patients show higher frequencies of micronuclei (17.2 +/- 4.8 vs. 9.0 +/- 3.4, p < 0.001) and a significant increase in the levels of single strand breaks (SSB). Significant differences were also obtained in the distribution of oxidised purine bases between the two groups. Preliminary data obtained by fluorescence in situ hybridization analysis showed that the percentage of centromere negative micronuclei is higher than that of centromere positive micronuclei. Glutathione S-transferase activity in plasma from PD patients and controls was also measured and the enzymatic activity in PD patients was lower than in healthy controls.