Toxicity associated with iron overload found in hemochromatosis: possible mechanism in a rat model.

Hemochromatosis is characterized by pathologic iron overload which often leads to various pathological conditions. The mechanism by which excess iron induces these conditions is not clearly understood. Using rats as the model, this investigation was conducted to explore the mechanism of toxicity associated with iron overload. Sprague-Dawley male rats were fed a 3% carbonyl iron-supplemented diet for eight weeks to achieve iron accumulation. Liver iron reached approximately 2 mg/g which is more than 16 times the control values (mean +/- SD, 0.12 +/- 0.02 mg/g, p < 0.001). Serum iron was consistently higher in the experimental rats (mg/L): 3.41 +/- 0.58 versus 1.89 +/- 0.18, p < 0.001. The high levels of iron accompanied enhanced oxidative damage in the hepatic nuclear DNA when 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured as a product of DNA oxidation. The levels of 8-OHdG in the experimental samples were significantly higher than the controls (8-OHdG X 10(-5)/dG): 4.22 +/- 1.82 versus 1.84 +/- 0.33, p < 0.05. The results of serum enzyme assays suggest that iron overload caused mild hepatocellular damage: alanine transaminase significantly increased; lactate dehydrogenase did not change; alkaline phosphatase decreased. Since the accumulation of 8-OHdG in the nuclear DNA is highly deleterious to cells, these data suggest oxidative damage in the nuclear DNA may be a critical factor in inducing diseases associated with iron overload.     

Low total antioxidant status is implicated with high 8-hydroxy-2-deoxyguanosine serum concentrations in phenylketonuria

BACKGROUND: Phenylketonuria (PKU), an inborn error of metabolism, is treated with a low phenylalanine (Phe) lifelong diet, which can be characterized as vegetarian. 8-Hydroxy-2-deoxyguanosine (8-OHdG) is highly implicated in degenerative diseases. OBJECTIVE: To evaluate the effect of plasma total antioxidant status (TAS) and Phe on the serum marker of DNA damage, 8-OHdG, in PKU. METHODS: Twenty-four PKU patients on a strict diet (group A), 25 PKU patients on a "loose diet" (group B), and 24 healthy children (controls) participated in this study. Plasma TAS was evaluated spectrophotometrically. 8-OHdG and Phe were measured in blood with immunoassays. RESULTS: TAS levels were significantly higher (P < 0.001) in group A (1458 +/- 140 micromol/L) and controls (1452 +/- 235 micromol/L) than those in group B (907 +/- 150 micromol/L). In contrast, 8-OHdG serum levels were 2-fold higher in group B (0.22 +/- 0.03 ng/mL) as compared with those in group A (0.11 +/- 0.02 ng/mL) and 3-fold higher than those in controls (0.08 +/- 0.02 ng/mL) (P < 0.001). As expected, Phe levels were also significantly higher in group B than those in the other study groups. Positive correlation coefficients were found between Phe and 8-OHdG levels, whereas negative correlations were evaluated between TAS and 8-OHdG in all groups. CONCLUSIONS: The high Phe and the low TAS plasma levels in PKU patients on a "loose diet" may induce DNA oxidation, as evidenced by the measured high 8-OHdG level in their sera. 8-OHdG evaluation may be a useful marker of increased risk for a neurodegenerative process.     

Association of NAD(P)H oxidase p22 phox gene variation with advanced carotid atherosclerosis in Japanese type 2 diabetes

OBJECTIVE: To evaluate the association between the C242T polymorphism of the p22 phox gene, an essential component of NAD(P)H oxidase in the vasculature, with intima-media thickness (IMT) of the carotid artery and risk factors for atherosclerosis in type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: C242T polymorphism of the p22 phox gene was detected by polymerase chain reaction-restriction fragment-length polymorphism in 200 Japanese type 2 diabetic subjects and 215 nondiabetic subjects. We examined the association with this mutation and carotid atherosclerosis as well as the patients' clinical characteristics and the level of 8-hydroxy-2'deoxyguanosine (8-OHdG) as an index of oxidative DNA damage. RESULTS: The diabetic subjects with the TC+TT genotypes displayed a significantly lower average IMT (1.13 +/- 0.31 vs. 1.31 +/- 0.34 mm; P = 0.0099) and a not significantly lower serum 8-OHdG level than those with the CC genotype, despite no difference in the risk factors. Stepwise multiple regression analysis showed that the risk factors for increased IMT in the diabetic subjects were systolic blood pressure (P = 0.0042) and p22 phox CC genotype (P = 0.0151). In nondiabetic subjects, the average IMT of the TC+TT group was not different from that of the CC group (0.85 +/- 0.14 vs. 0.94 +/- 0.30 mm, P = 0.417). Fasting plasma insulin concentration (41.4 +/- 15.6 vs. 64.2 +/- 59.4 pmol/l, P = 0.0098) and insulin resistance index of homeostasis model assessment (HOMA-R) (1.58 +/- 0.66 vs. 2.60 +/- 2.56, P = 0.0066) were significantly lower in the TC+TT group than in the CC group. CONCLUSIONS: These results show that the C242T mutation in the p22 phox gene is associated with progression of asymptomatic atherosclerosis in the subjects with type 2 diabetes and is also associated with insulin resistance in nondiabetic subjects.     

Facilitated nitration and oxidation of LDL in cigarette smokers

BACKGROUND: Cigarette smoking increases the risk of developing atherosclerosis and ischaemic heart disease. Smoking-induced oxidative stress is considered to favour oxidation of low-density lipoprotein (LDL) and subsequently promotes the atherogenic process. We investigated whether peroxynitrite, a reaction product of cigarette smoke, is involved in facilitated oxidation of LDL in smokers. MATERIALS AND METHODS: Plasma LDL was obtained from 10 healthy asymptomatic cigarette smokers and 10 healthy nonsmokers. The state of enhanced oxidative stress in the plasma was assessed by LDL subfraction assay using anion-exchange high-performance liquid chromatography (AE-HPLC) and measurements of thiobarbituric acid-reactive substances (TBARS), 8-hydroxydeoxyguanosine (8-OHdG), vitamin E, 3-nitrotyrosine and 3-chlorotyrosine. RESULTS: Smokers showed a significantly higher level of TBARS and 8-OHdG as well as a significantly lower level of vitamin E than nonsmokers, even after stopping smoking for 10 h or more. The LDL subfraction assay demonstrated an increase in oxidatively modified LDL, as expressed by lower levels of LDL1 and higher levels of LDL2. The 3-nitrotyrosine levels in apolipoprotein B in LDL were significantly higher in smokers than nonsmokers, while the 3-chlorotyrosine levels remained unchanged. In addition, these changes observed in the smokers were further accelerated within 30 min after resumption of cigarette smoking when compared with the levels before smoking resumption. CONCLUSION: The present study suggests that peroxynitrite plays a significant role in oxidative modification of plasma LDL induced by cigarette smoking.     

alpha-tocopherol supplementation reduces the elevated 8-hydroxy-2-deoxyguanosine blood levels induced by training in basketball players.

BACKGROUND: The aim of the present study was to investigate the effect of alpha-tocopherol (alpha-Te) supplementation on DNA oxidative damage induced by heavy training in basketball players. METHODS: Blood was obtained from 10 players before (group A) and after training (group B) and after 1 month on alpha-Te (200 mg/day, orally) supplementation, before (group C) and after training (group D). Total antioxidant status (TAS), muscle enzyme activities and the biomarker of DNA oxidation, 8-hydroxy-2-deoxyguanosine (8-OHdG), were measured using commercial kits. alpha-Te and catecholamine blood levels were determined using HPLC methods. RESULTS: TAS was higher in the groups with alpha-Te (groups C and D). Levels of 8-OHdG and muscle creatine kinase (CK) and lactate dehydrogenase (LDH) were remarkably lower (0.20+/-0.03 ng/mL, 120+/-15 U/L and 430+/-90 U/L, respectively) in the group with alpha-Te (group D) than in group B (0.42+/-0.05 ng/mL, 286+/-12 U/L and 688+/-88 U/L, respectively; p<0.001). 8-OHdG levels were negatively correlated to TAS and positively to CK levels. CONCLUSIONS: alpha-Te supplementation may reduce DNA oxidation induced by training by protecting muscle cell "death" from glutamate entry and/or by elevation of TAS via amelioration of lipid peroxidation.     

原发性肝癌患者尿8-羟基脱氧鸟苷水平的观察

目的通过测定和比较原发性肝癌患者与健康体检者尿8-羟基脱氧鸟苷水平,探讨DNA氧化损伤与肝癌发生发展的关系。方法以酶联免疫吸附法检测各100例肝癌患者（实验组）及健康体检者（对照组）尿8-OHdG水平,并进行相互比较。结果肝癌患者尿8-OHdG水平明显高于健康体检者（16．12±5．30VS12．21±4．51）ng／mgCr（P〈0．01）。结论肝癌患者尿8-OHdG水平高于健康人群,DNA氧化损伤与肝癌发生发展具有密切的关系,测定尿8-OHdG水平有助于肝癌的诊治。     

Human liver disease decreases methacrylyl-CoA hydratase and beta-hydroxyisobutyryl-CoA hydrolase activities in valine catabolism

Oxidative modification of LDL induces immunogenic epitopes in the LDL molecule, and the presence of antibodies against oxidized LDL (anti-Ox-LDL) has been demonstrated in human sera. However, little is known about the clinical significance of anti-Ox-LDL. To elucidate a clinical relationship between the immunological response to oxidized LDL and cellular oxidative stress, we measured serum titers of anti-Ox-LDL in 45 unselected patients with hypercholesterolemia and serum 8-hydroxy-2'-deoxyguanosine (8-OHdG), considered a biomarker of the oxidative damage to DNA. The anti-Ox-LDL titer was not correlated with the serum LDL-C concentration, but was correlated with the 8-OHdG concentration (r = 0.300, P < 0.05) in a simple linear regression. Multiple regression analysis indicated that 8-OHdG was independently correlated with anti-Ox-LDL (r = 0.429, P < 0.05), but no other variables, including LDL-C concentrations and smoking habit, were correlated with anti-Ox-LDL. In 16 subgroup patients, the concentrations of TC, TG and LDL-C decreased and the HDL-C concentration increased after cholesterol-lowering therapy with fluvastatin. In addition, both the anti-Ox LDL titer (14.0 +/- 9.5 to 11.4 +/- 6.6 AcU/ml, P < 0.05) and the 8-OHdG concentration (1.19 +/- 0.41 to 0.85 +/- 0.43 ng/ml, P < 0.05) also decreased after fluvastatin therapy. The immunological response to LDL oxidation on vascular wall tissues or cells appear to occur in association with oxidative DNA damage. The measurement of anti-Ox-LDL may be a useful indicator for lipid-lowering therapy.     

Oxidative stress biomarkers in four Bloom syndrome (BS) patients and in their parents suggest in vivo redox abnormalities in BS phenotype

OBJECTIVE: To evaluate an association of Bloom syndrome (BS) phenotype with an in vivo prooxidant state. METHODS: The following endpoints were measured in 4 BS patients, their 6 parents, and 78 controls: a) leukocyte and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG); b) blood glutathione (GSSG and GSH), c) plasma levels of some plasma antioxidants (uric acid, UA, ascorbic acid, AA, alpha- and gamma-tocopherol), and of glyoxal (Glx) and methylglyoxal (MGlx). RESULTS: Leukocyte 8-OHdG levels were significantly increased in the 4 BS patients vs. 40 controls (p=0.04), while the urinary 8-OHdG levels were non-significantly increased in BS patients. Glutathione disulfide levels and GSSG/GSH ratio were significantly decreased in BS patients vs. 44 controls (p=0.02). The plasma levels of UA in BS patients were significantly increased vs. 24 controls (p=0.005). No significant alterations were found in the in the plasma levels of Glx, MGlx, AA, and tocopherol. No changes in the tested parameters were found in the BS heterozygotes. CONCLUSION: This report shows a significant increase in oxidative DNA damage in leukocytes and in plasma UA levels from 4 BS patients. Should these data be confirmed in more extensive BS patient groups, an involvement of oxidative stress in the clinical BS phenotype might be suggested.     

Influence of increased fruit and vegetable intake on plasma and lipoprotein carotenoids and LDL oxidation in smokers and nonsmokers

BACKGROUND: Epidemiological studies suggest a cardioprotective role for carotenoid-rich foods. Smokers have a high risk of cardiovascular disease and low dietary intake and plasma concentrations of carotenoids. The aim of this study was to determine the carotenoid response of smokers and nonsmokers to increased intake of 300-400 g of vegetables and its effect on LDL oxidation. METHODS: After a depletion period of 8 days, 34 healthy females (18 nonsmokers, 16 smokers) were supplemented with beta-carotene- and lutein-rich (green) and lycopene-rich (red) vegetable foods, each for 7 days. RESULTS: Baseline concentrations (mean +/- SD) of plasma beta-carotene (0.203+/-0.28 micromol/L vs. 0.412+/-0.34 micromol/L; P <0.005) and lutein (0.180 +/-0.10 vs. 0.242+/-0.11 micromol/L; P<0.05) but not lycopene (0.296+/-0.10 vs. 0.319+/-0.33 micromol/L) were significantly lower in smokers compared with nonsmokers. After supplementation, the change (supplementation minus depletion) in plasma beta-carotene (0.152+/- 0.43 vs. 0.363+/-0.29 micromol/L in smokers vs. nonsmokers; P = 0.002) and LDL lutein (0.015+/-0.03 vs. 0.029+/-0.03 micromol/mmol cholesterol; P = 0.01) was significantly lower in smokers than nonsmokers. Green-vegetable supplementation had no effect on the resistance of LDL to oxidation (lag-phase) in either group. After red-vegetable supplementation, plasma and LDL lycopene concentrations were increased in both groups, but only nonsmokers showed a significant increase in the lag-phase (44.9+/-9.5 min at baseline, 41.4+/-6.5 min after depletion, and 49.0+/-8.9 min after supplementation; P<0.01) compared with depletion. CONCLUSIONS: In this short-term intervention study, a dietary intake of >40 mg/day of lycopene by a group of nonsmoking individuals significantly reduced the susceptibility of LDL to oxidation, whereas an equivalent increase in lycopene by a group of smokers showed no such effect.     

Isotretinoin therapy induces DNA oxidative damage.

BACKGROUND: Isotretinoin (Iso) is currently indicated for the treatment of cystic acne (CA) and is related to marked teratogenicity. AIM: The aim of the study was to evaluate the relationship between total antioxidant status (TAS) and a serum marker of DNA oxidative damage, 8-hydroxy-2-desoxyguanosine (8-OHdG), in patients on Iso treatment. PATIENTS AND METHODS: Patients with CA (n=18) were evaluated before and 45 days after Iso (0.5 mg/kg per day) treatment and non-diseased controls (n=22) were tested only once. Plasma TAS levels and 8-OHdG were measured spectrophotometrically and with an immunoassay, respectively. Liver biochemical parameters and muscle enzymes were measured on a blood chemistry analyzer. RESULTS: TAS levels were significantly (p<0.0001) lower in patients before treatment (921+/-124 micromol/L) compared with those after treatment (1335+/-93 micromol/L) and in controls (1536+/-126 micromol/L). In contrast, 8-OHdG serum levels were two-fold higher in patients after treatment (0.21+/-0.03 ng/mL) than before treatment (0.11+/-0.02 ng/mL) and three-fold higher than in controls (0.07+/-0.01 ng/mL; p<0.0001). Negative correlations were found between TAS and 8-OHdG (r=-0.754, p<0.0001) in patients before therapy and positive correlations were found between creatine kinase (CK) and 8-OHdG (r=0.488, p<0.001) and liver enzymes after Iso treatment. CONCLUSIONS: High serum levels of 8-OHdG in patients on Iso therapy may be due to a direct effect of Iso on liver, muscle and skin epidermal cells. Regular evaluation of 8-OHdG in sera of patients, especially of women of reproductive age, on Iso treatment could be a sensitive follow-up biomarker of DNA oxidation.     

Environmental Arsenic Exposure and Urinary 8-OHdG in Arizona and Sonora

Although at high levels arsenic exposure is associated with increased cancer incidence, information on the health effects of lower exposure levels is limited. The objective of this study was to determine whether arsenic at concentrations below 40 microg/L in drinking water is associated with increased urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of DNA oxidative damage and repair. Urine samples were collected from 73 nonsmoking adults residing in two communities in Arizona (mean tap water arsenic (microg/L) 4.0 +/- 2.3 and 20.3 +/- 3.7), and 51 subjects in four communities in Sonora, Mexico (mean tap water arsenic (microg/L) ranging from 4.8 +/- 0.1 to 33.3 +/- 0.6). Although urinary arsenic concentration increased with higher exposure in tap water, urinary 8-OHdG concentration did not differ by community within Arizona or Sonora, and was not associated with urinary arsenic concentration. At the exposure levels evaluated in this study, drinking water arsenic was not associated with increased DNA oxidation as measured by urinary 8-OHdG.     

Acute in vivo chylomicron metabolism and postalimentary lipoprotein alterations in normolipidemic male smokers

Increased postprandial lipemia has been stated as one of the mechanisms responsible for atherogenesis in smokers. We measured the postalimentary lipid response and the in vivo intravascular delipidation index of an artificial chylomicron emulsion in healthy adult smokers and controls. The blood was collected in the fasting state immediately after the smokers smoked one cigarette. The lipemia was measured 2, 4, 6 and 8 h postalimentarily in smokers (S, n = 8) and in non-smoking controls (C, n = 8) and the chylomicron metabolism rate was measured 2, 4, 6, 8, 12, 16, 20, 24 and 30 min after the injection of an artificial emulsion to S (n = 10) and to C (n = 10). The lipoproteins were isolated in the fasting period and 4 h after the fatty meal and their chemical composition in cholesterol, triglycerides, phospholipids and protein was determined. Smokers showed an increased lipolysis percentage value (mean +/- S.E.M.) of the artificial chylomicron (39.1 +/- 3.1) compared to controls (26.5 +/- 3.3) and higher levels of HDL(2)-PL: 28.4 +/- 4.3 (S) versus 16.2 +/- 2.0 (C) mg/dl (mean +/- S.E.M.). In conclusion, the oral fat tolerance was not altered in smokers but an upregulation of the rate of metabolism of the TG-rich lipoproteins was elicited immediately after smoking one cigarette.     

Urinary 8-OHdG: a marker of oxidative stress to DNA and a risk factor for cancer, atherosclerosis and diabetics

Reactive oxygen species (ROS) produced either endogenously or exogenously can attack lipid, protein and nucleic acid simultaneously in the living cells. In nuclear and mitochondrial DNA, 8-hydroxydeoxyguanosine (8-OHdG), an oxidized nucleoside of DNA, is the most frequently detected and studied DNA lesion. Upon DNA repair, 8-OHdG is excreted in the urine. Numerous evidences have indicated that urinary 8-OHdG not only is a biomarker of generalized, cellular oxidative stress but might also be a risk factor for cancer, atherosclerosis and diabetes. For example, elevated level of urinary 8-OHdG has been detected in patients with various cancers. In human atherosclerotic plaques, there were increased amounts of oxidatively modified DNA and 8-OHdG. Elevated urinary 8-OHdG and leukocyte DNA were also detected in diabetic patients with hyperglycemia, and the level of urinary 8-OHdG in diabetes correlated with the severity of diabetic nephropathy and retinopathy. We have discussed various methods for determining 8-OHdG in the tissue and urine, including HPLC with and without extraction, and ELISA. Using the ELISA we developed, we found that the normal range of urinary 8-OHdG for females was 43.9 +/- 42.1 ng/mg creatinine and 29.6 +/- 24.5 ng/mg creatinine for males, respectively. We found that the normal value between females and males is significantly different (p < 0.001).     

Increased Plasma Levels of 8-Hydroxydeoxyguanosine Are Associated with Development of Colorectal Tumors

Increased oxidative stress is generally thought to be associated with tumorigenesis. In this cross-sectional study, we evaluated plasma 8-hydroxydeoxyguanosine (8-OHdG) levels in patients with colorectal adenoma and cancer, as a surrogate marker of oxidative damage to deoxyribonucleic acid (DNA). We collected blood samples from 58 patients with adenoma, 32 with early cancer, 25 with advanced cancer, and 36 without polyps or cancer (as controls), and measured plasma levels of 8-OHdG by enzyme-linked immunosorbent assay. Univariate analysis by logistic regression showed that an increased level of 8-OHdG was a significant risk for adenoma [odds ratio (OR) 1.393, 95% confidence interval (CI) 1.008–1.926, p = 0.045]. In patients with early cancer, univariate analysis revealed significant differences for age, body mass index (BMI), systolic blood pressure, and 8-OHdG level. Subsequent multivariate analysis revealed that 8-OHdG [OR 1.627, 95% CI 1.079–2.453, p = 0.020] and BMI [OR 1.283, 95% CI 1.038–1.585, p = 0.021] were significant risk factors for early cancer. However, 8-OHdG was not a significant risk factor for advanced cancer. Our results suggest that an increased plasma level of 8-OHdG is associated with development of colorectal adenoma and cancer.     

Effect of smoking on plasma neutrophil elastase levels

Plasma elastase is considered to indicate neutrophil elastase that has been released in vivo and has complexed with plasma inhibitors. Because smoking may play a pathogenetic role in emphysema by inducing elastase release in the lung, which may be reflected in the plasma elastase level, we evaluated the effect of smoking on plasma elastase in healthy men by using an enzyme-linked immunosorbent assay. No significant difference was found in plasma elastase levels between 30 smokers and 29 nonsmokers (103 +/- 23 [SD] ng/ml vs. 97 +/- 23 ng/ml). We found no significant change in plasma elastase level in eight heavy smokers when we compared morning with afternoon plasma samples taken about 7 hours later, while the subjects continued to smoke ad libitum in the interval. However, we found a significant rise in plasma elastase level in 12 healthy smokers who were tested after 8 hours of abstinence from smoking and then immediately and 1/2, 1, and 2 hours after intense smoking (eight cigarettes smoked over a period of 2 hours). Neutrophil count increased from a baseline of 3.8 +/- 0.7 X 10(3)/mm3 to 8.0 +/- 2.5 X 10(3)/mm3 at 1 hour, and 8.8 +/- 3.1 X 10(3)/mm3 at 2 hours. Plasma elastase level increased significantly (P less than 0.02) from a baseline of 111 +/- 30 ng/ml to 141 +/- 24 ng/ml at 1 hour after completion of smoking, but was not significantly different from baseline 2 hours after smoking (130 +/- 34 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

hOGG1 Genotype, Green Tea and Oxidative DNA Damage among Heavy Smokers

DNA is susceptible to damage by reactive oxygen species, and 8-hydroxydeoxyguanosine (8-OHdG) is probably one of the most abundant DNA lesions formed during oxidative stress. Several pathways exist for the removal or repair of this lesion from mammalian DNA. The most established is via the base excision repair enzyme, human 8-oxoguanine glycosylase (hOGG1). Several polymorphisms in the hOGG1 gene have been detected in human populations. We were interested in whether there were differences in increased oxidative stress susceptibility to smoking within the hOGG1 genotypes and the impact of high tea drinking on this. A phase IIb randomised, controlled, tea intervention trial was designed to study the effect of high consumption (four cups per day) of decaffeinated green or black tea on oxidative DNA damage, as measured by urinary 8-OHdG, among smokers over a 4-month period and to evaluate the role of the hOGG1 genotype as an effect modifier. A total of 120 smokers with hOGG1 data completed the 4-month intervention. The hOGG1 genotype status was determined with a polymerase chain reaction-based approach. Multiple linear regression models were used to estimate the main effects and interaction effect of green and black tea consumption on creatinine-adjusted urinary 8-OHdG, with or without adjustment for potential confounders. Finally, we studied whether the effect of treatment varied by hOGG1 status of the individual. Assessment of urinary 8-OHdG after adjustment for baseline measurements and other potential confounders revealed a highly significant decrease in urinary 8-OHdG after 4 months of drinking decaffeinated green tea (p = 0.001). No change in urinary 8-OHdG was seen among smokers assigned to the black tea group. We found the distribution of hOGG1 Ser326Cys genotypes among smokers to be 62%, 28% and 10% for Ser/Ser, Ser/Cys and Cys/Cys genotypes, respectively. Because the homozygous Cys/Cys genotype was present in only 10% of the study population, the mutant types (Ser/Cys and Cys/Cys) were combined and compared with the Ser/Ser genotype. We found no significant interaction between smoking, hOGG1 genotypes and tea intervention in terms of levels of urinary 8-OHdG. This finding suggests that green tea intervention might be effective in decreasing levels of urinary 8-OHdG among smokers regardless of their hOGG1 genotype.     

Lipolysis generates platelet dysfunction after in vivo heparin administration

Heparin, when administered to patients undergoing operations using cardiopulmonary bypass, induces plasma changes that gradually impair platelet macroaggregation, but heparinization of whole blood in vitro does not have this effect. The plasma changes induced by heparin in vivo continue to progress in whole blood ex vivo. Heparin releases several endothelial proteins, including lipoprotein lipase, hepatic lipase, platelet factor-4 and superoxide dismutase. These enzymes, which remain active in plasma ex vivo, may impair platelet macroaggregation after in vivo heparinization and during cardiopulmonary bypass. In the present study, proteins were added in vitro to hirudin (200 units.ml(-1))-anticoagulated blood from healthy volunteers, and the platelet macroaggregatory responses to ex vivo stimulation with collagen (0.6 microg.ml(-1)) were assessed by whole-blood impedance aggregometry. Over a 4 h period, human lipoprotein lipase and human hepatic lipase reduced the platelet macroaggregatory response from 17.0+/-2.3 to 1.5+/-1.3 and 1.2+/-0.6 Omega respectively (means+/-S.D.) (both P <0.01; n =6). Other lipoprotein lipases also impaired platelet macroaggregation, but platelet factor-4 and superoxide dismutase did not. Platelet macroaggregation showed an inverse linear correlation with plasma concentrations of non-esterified fatty acids ( r (2)=0.69; two-sided P <0.0001; n =8), suggesting that heparin-induced lipolysis inhibits platelet macroaggregation. Lipoprotein degradation products may cause this inhibition by interfering with eicosanoids and other lipid mediators of metabolism.     

The effect of smoking on the urinary excretion of 8-oxodG and 8-oxoGuo in patients with type 2 diabetes

Over the past decades, attention has been paid to understanding the impact of oxidative stress and related modifications of DNA and RNA on various human health risks. A recent meta-analysis comprising 1915 smokers and 3462 non-smokers found a significantly higher level of DNA oxidation measured as urinary 8-oxo-7, 8-dihydro-2′-deoxyguanosine (8-oxodG) excretion in smokers compared with non-smokers in a healthy population. We aimed to investigate if an increased urinary excretion of 8-oxodG in smokers versus never smokers and former smokers could be verified in a population with type 2 diabetes. Additionally, we measured RNA oxidation levels through urinary excretion of 8-oxo-7, 8-dihydroguanosine (8-oxoGuo). Our study included urinary samples from 2721 type 2 diabetic patients, analyzed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Logistic regression was used to examine the relationship between daily smokers (n?=?462) versus former (n?=?1341) and never smokers (n?=?918) regarding the RNA and DNA oxidation, respectively. We did not find any significant effect of smoking on urinary excretion of 8-oxodG or 8-oxoGuo in our study. Due to a sparse study area, it is still too early to draw any conclusions on smoking and RNA-oxidation. Regarding DNA oxidation, our study suggests that the effect of smoking seen in healthy populations might be attenuated in patients with type 2 diabetes.     

Smoking or its cessation does not alter the susceptibility to in vitro LDL oxidation

BACKGROUND: Enhanced induction of low density lipoprotein (LDL) oxidation may play a role in the increased cardiovascular risk in smokers. We determined LDL oxidisability in vitro in non-smokers, smokers and in subjects after smoking cessation. PATIENTS AND METHODS: Plasma lipids and copper induced LDL oxidation in vitro were measured in 31 persistent smokers, 47 smokers who tried to stop smoking and 25 non-smokers. In the smoking cessation group, blood was collected before then 1, 3, 6 and 12 months after smoking cessation, and in the persistent smoking and non-smoking groups at baseline and after 12 months. Plasma thiobarbituric acid reactive substances (TBARS) were measured 3 times (at baseline then after 1 and 3 months) in all subjects who refrained from smoking (controlled by urinary cotinine concentrations) for at least 3 months. RESULTS: At baseline, no differences in mean age, body mass index and lipid profiles between groups were present. Seventeen subjects of the smoking cessation group (36%) managed to quit during 12 months. Smoking cessation was associated with an increase in mean weight (P 相似文献   

Oxidative Stress Biomarkers and Lifestyles in Japanese Healthy People

The urinary concentrations of 8-isoprostane and 8-hydroxy-2’-deoxyguanosine (8-OHdG), which are biomarkers of oxidative stress, were measured in 677 Japanese people without any diseases, and their correlations with lifestyle facotrs, lifestyle-related blood biochemical parameters, and dietary intake of antioxidative vitamins were investigated. The mean urinary concentration of 8-isoprostane and 8-OHdG was 0.58 ng/mg creatinine and 8.43 ng/mg creatinine, respectively. Mean urinary 8-isoprostane was significantly different in terms of age, gender, smoking and alcohol consumption but not different in terms of body mass index (BMI) and exercise. By multiple regression analysis, urinary 8-isoprostane was significantly influenced by smoking and age. On the other hand, mean urinary 8-OHdG showed differences only by age group. Multiple regression analysis revealed that urinary 8-OHdG was significantly influenced by age, smoking, body weight, levels of high-sensitivity C-reactive protein (Hs-CRP) and low density lipoprotein-cholesterol in females, although it was significantly influenced by body weight in males. The present study shows that urinary 8-isoprostane is associated with lipid peroxidation related-lifestyles such as smoking, and urinary 8-OHdG is associated with arteriosclerosis related-factors such as Hs-CRP. Our findings suggest that 8-isoprostane and 8-OHdG appear to be prospective biomarkers for early prediction of lifestyle related-disease risk at the population level.