Effect of mercury (Hg) dental amalgam fillings on renal and oxidative stress biomarkers in children

We examined the effect of mercury (Hg) associated with dental amalgam fillings on biomarkers of renal and oxidative stress in children between the ages of 5-15.5 years. Urine samples were analyzed for N-acetyl-β-D-glucosaminidase (NAG), α(1)-microglobulin (α(1)-MG), β(2)-microglobulin (β(2)-MG), retinol binding protein (RBP), albumin (ALB), 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The level of urinary Hg (UHg-C) was calculated as μg/g creatinine. Multiple regression analyses revealed that the excretion of urinary NAG was significantly associated with the presence of dental amalgam fillings (β=0.149, P=0.03) and the levels of UHg-C (β=0.531, P=0), with an interaction between the two (P=0). The increase in urinary NAG in relation to UHg-C levels had a dose-effect pattern. The lowest observed effect was seen at UHg-C levels above 1.452 μg/g creatinine, which is lower than previously reported. In contrast, α(1)-MG was negatively associated with the presence of dental amalgam fillings (β=-0.270, P=0), but positively with UHg-C levels (β=0.393, P=0). There were 7 children without, and one child with, dental amalgam fillings with urinary α(1)-MG levels above the reference limit of >7 mg/g creatinine. Even though α(1)-MG seems to be a reliable biomarker for early changes in renal functions, it might exert its effect only at a higher level of exposure. An inverse relationship was also observed between urinary 8-OHdG levels and the presence of dental amalgam fillings. This might suggest that the dental amalgam does not increase DNA damage but reduces the capacity to repair DNA, leading to lower urinary excretion of 8-OHdG. On the other hand, we found that Hg affected the excretion of urinary 8-OHdG in a dose-related pattern that was mostly associated with long-term exposure to low Hg levels. Urinary NAG levels were positively associated with urinary MDA levels (β=0.516, P=0) but not with 8-OHdG (β=0.134, P=0.078) after adjustment for potential confounders. Both UHg-C and the presence of dental amalgam fillings remained predictors of the NAG model. Our data provide evidence that low exposure to Hg from dental amalgam fillings exerts an effect on kidney tubular functions in children. Oxidative stress may have played a role in this mechanism. The results of this study would also suggest that urinary NAG is the most sensitive of all the investigated renal biomarkers. These results should be confirmed with further investigation.

[Effect of dibutyl phthalate and di-(2-ethylhexyl) phthalate on urine SOD activity and MDA content in rats]

OBJECTIVE

To evaluate the effect of dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) on urine superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in rats.

METHODS

According to 2×2 factorial analysis, 60 adult male SD rats were randomized into 10 groups (n=6), including a control group (fed with sesame oil), 3 DBP groups (fed with DBP at the doses of 30, 100 and 300 mg/kg), 3 DEHP groups (with DEHP at 50, 150, and 450 mg/kg), and 3 DBP+DEHP groups (with 30 mg/kg DBP+50 mg/kg DEHP, 100 mg/kg DBP+150 mg/kg DEHP, and 300 mg/kg DBP +450 mg/kg DEHP). The agents were administered in a single dose through gavage in a volume of 2 ml. After the treatments, the 24, 48, 72, and 96 h urine samples were collected to determine the SOD activity and MDA content.

RESULTS

DBP and DEHP, either alone or in combination, significantly decreased SOD activity and increased MDA content in the urine collected at 24 h but not at the other time points. Such changes were gradually reversed with time.

CONCLUSION

DBP or DEHP treatment alone can result in significant oxidative damage in the kidney of rats, and the toxic effect of the combined exposure is even more obvious.

Determination of urinary malondialdehyde by isotope dilution LC-MS/MS with automated solid-phase extraction: a cautionary note on derivatization optimization

A highly sensitive quantitative LC-MS/MS method was developed for measuring urinary malondialdehyde (MDA). With the use of an isotope internal standard and online solid-phase extraction, urine samples can be directly analyzed within 10 min after 2,4-dinitrophenylhydrazine (DNPH) derivatization. The detection limit was estimated as 0.08 pmol. This method was further applied to assess the optimal addition of DNPH for derivatization and to measure urinary MDA in 80 coke oven emission (COE)-exposed and 67 nonexposed workers. Derivatization optimization revealed that to achieve complete derivatization reaction, an excess of DNPH is required (DNPH/MDA molar ratio: 893-8929) for urine samples that is about 100 times higher than that of MDA standard solutions (molar ratio: 10-80). Meanwhile, the mean urinary concentrations of MDA in COE-exposed workers were significantly higher than those in nonexposed workers (0.23±0.17 vs 0.14±0.05 μmol/mmol creatinine, P<0.005). Urinary MDA concentrations were also significantly associated with the COE (P<0.005) and smoking exposure (P<0.05). Taken together, this method is capable of routine high-throughput analysis and accurate quantification of MDA and would be useful for assessing the whole-body burden of oxidative stress. Our findings, however, raise the issue that derivatization optimization should be performed before it is put into routine biological analysis.

In vivo antioxidant potential of Sweet chestnut (Castanea sativa Mill.) wood extract in young growing pigs exposed to n-3 PUFA-induced oxidative stress

BACKGROUND

Farm animals in intensive farming systems are frequently exposed to oxidative stress, which demands adequate antioxidant protection. The aim of this study was to evaluate the antioxidant potential of different concentrations of Sweet chestnut wood extract (SCW; 0.75, 1.5 and 3 g kg⁻¹) in case of n-3 PUFA-induced oxidative stress in young pigs.

RESULTS

The highest concentration (3 g kg⁻¹) of SCW decreased malondialdehyde excretion in urine by 31.7%, but had no effect on plasma malondialdehyde. A linear trend towards decrease of urine isoprostanes iPF(2α)-VI was observed with the addition of SCW. All three concentrations of SCW efficiently protected blood lymphocytes from DNA damage and lowered plasma alanine aminotransferase levels. The antioxidative and antigenotoxic effect of 3 g SCW kg⁻¹ feed was comparable to the effect of 90.4 mg kg⁻¹ of added vitamin E.

CONCLUSION

The results from this study show that, besides being known as antihelmintic, antimicrobial and antiviral agent, Sweet chestnut wood extract could also be considered as a promising natural antioxidant in animal nutrition.

[Effect of a simulated He-O2 saturation dive to 65 msw on oxidative stress in humans]

OBJECTIVE

To investigate whether a simulated He-O2 saturation dive to 65 msw would affect oxidative balance in humans.

METHODS

Seven divers participated in a simulated saturation dive to 0.75 MPa (65 msw). 24-h urine samples were collected twice before, twice during, and twice after the dive, then were analyzed for contents of superoxide dismutase (SOD), malondialdehyde (MDA), total amino acid (T-AA) and total anti-oxidant capacity (T-AOC). Meanwhile, total urine volume and body weight were measured.

RESULTS

The content of T-AA was higher. (P < 0.05) than the base value in final decompression, but reverse to normal at one week after decompression. There were no changes in contents of SOD, MDA and T-AOC during and after the dive compared with their basic value. Total urine volume was lower (P < 0.05, vs basic value) at first day in chamber, then returned to normal. Body weight gradually increased after compression till the end of decompression (higher than basic value, P < 0.05).

CONCLUSION

These data indicate that simulated saturation dive to 65 msw may not induce obvious oxidative damage, but it is necessary to monitor 24-h urine volume and oxidative sress by time in order to prevent from tissue injury.

Correlation of Ochratoxin A exposure to urinary levels of 8-hydroxydeoxyguanosine and malondialdehyde in a Turkish population

Ochratoxin A is one of the most abundant food- contaminating mycotoxins in the world that is immunosuppressive, genotoxic, teratogenic and carcinogenic. Malondialdehyde is a naturally occurring product of lipid peroxidation that is mutagenic and carcinogenic. 8-Hydroxydeoxyguanosine is produced during the interaction of reactive oxygen species and DNA. In this study, Ochratoxin A, malondialdehyde and 8-Hydroxydeoxyguanosine levels of individuals in the study group were measured and results were correlated with each other. Additionally, the correlation of biomarker levels to smoking habit, alcohol and coffee consumption, age and gender of individuals was investigated. As a result of these assessments, a significant correlation was observed between Ochratoxin A exposures and malondialdehyde and 8-Hydroxydeoxyguanosine levels.

[Correlation between urine malondialdehyde level and males reproductive success in the water vole (Arvicola terrestris L.)]

The study was conducted in water vole (Arvicola terrestris L.) reared and bred in captivity. During the breeding season, voles were caged in heterosexual pairs for two weeks. If mating did not occur, new pairs were formed with unfamiliar partners. In the end of the breeding season, the individual male's reproductive characteristics were summarized, and the level of malondialdehyde (MDA) in their urine was assessed. As indicated by urine MDA concentration, the intensity of lipid peroxidation in males which could not became fathers was significantly higher than in fertile males. In the last group, the negative correlation between average numbers of pups in litter and urine MDA concentration was revealed. It is possible, that a causal factor of water vole males lowered fertility is oxidative stress.

Changes in oxidative stress biomarker and gene expression levels in workers exposed to volatile organic compounds

Exposure to volatile organic compounds (VOCs) was known to result in immunologic, respiratory, carcinogenic, reproductive, neurologic, and cardiovascular effects. However, the mechanisms by which VOCs induce these adverse health effects are not well understood. To evaluate the change of oxidative stress biomarker and gene expression levels in workers exposed to VOCs, we obtained urine and blood samples from 21 subjects before and after occupational exposure to VOCs. We measured levels of muconic acid (MuA), hippuric acid (HA), mandelic acid (MaA), and methyl hippuric acid (MHA) as urinary exposure biomarkers for benzene, toluene, ethylbenzene, and xylene (collectively BTEX), and malondialdehyde (MDA) and 8-hydroxydeoxyguanine (8-OHdG) as oxidative stress biomarkers in all subjects. We also evaluated BTEX-mediated RNA expression using cDNA microarray in 14 subjects. HA and MHA levels were higher following occupational exposure to VOCs (p < 0.01). In the linear regression analysis, HA ratios of after- and before-exposure were found to be significantly associated with increase of MDA ratios of after- and before-exposure after controlling for age, body mass index, and smoking (β = 0.06, p = 0.031). Evaluation of the gene expressions by HA showed that 23 gene expressions were found to be significantly associated with HA levels after adjusting for age, body mass index, and smoking (p < 0.001). In particular, expressions of ENO3 and CDNA FLJ39461 fis among the 23 genes were significantly associated with the change in MDA level (p < 0.05). Our study results suggest that exposure to VOCs, specifically toluene, induces oxidative stress and various gene expression change of which some may be responsible for oxidative stress.

Influence of a five-day vegetarian diet on urinary levels of antibiotics and phthalate metabolites: a pilot study with "Temple Stay" participants

Diet is purported to be means of exposure to many environmental contaminants. The purpose of this study is to understand the influence of dietary change on the levels of exposure to several environmental chemicals - in particular, antibiotics and phthalates. For this purpose, we examined the extent to which short-term changes in diet influenced the inadvertent exposure levels to these chemicals in an adult population. We recruited participants (n=25) of a five-day 'Temple Stay' program in Korea and collected urine samples before and after the program. We also conducted a questionnaire survey on participants' dietary patterns prior to their participation. During the program, participants followed the daily routines of Buddhist monks and maintained a vegetarian diet. Urinary levels of three antibiotics and their major metabolites, metabolites of four major phthalates, and malondialdehyde (MDA) as an oxidative stress biomarker were analyzed. The frequency and levels of detection for antibiotics and phthalates noticeably decreased during the program. Urinary MDA levels were significantly lower than before program participation (0.16 versus 0.27mg/g creatinine). Although the exposure to target compounds might be influenced by other behavioral patterns, these results suggest that even short-term changes in dietary behavior may significantly decrease inadvertent exposure to antibiotics and phthalates and hence may reduce oxidative stress levels.

Antioxidant-rich spice added to hamburger meat during cooking results in reduced meat, plasma, and urine malondialdehyde concentrations

BACKGROUND

Emerging science has shown the effect of oxidation products and inflammation on atherogenesis and carcinogenesis. Cooking hamburger meat can promote the formation of malondialdehyde that can be absorbed after ingestion.

OBJECTIVE

We studied the effect of an antioxidant spice mixture on malondialdehyde formation while cooking hamburger meat and its effects on plasma and urinary malondialdehyde concentrations.

DESIGN

Eleven healthy volunteers consumed 2 kinds of burgers in a randomized order: one burger was seasoned with a spice blend, and one burger was not seasoned with the spice blend. The production of malondialdehyde in burgers and malondialdehyde concentrations in plasma and urine after ingestion were measured by HPLC.

RESULTS

Rosmarinic acid from oregano was monitored to assess the effect of cooking on spice antioxidant content. Forty percent (19 mg) of the added rosmarinic acid remained in the spiced burger (SB) after cooking. There was a 71% reduction in the malondialdehyde concentration (mean +/- SD: 0.52 +/- 0.02 micromol/250 g) in the meat of the SBs compared with the malondialdehyde concentration (1.79 +/- 0.17 micromol/250 g) in the meat of the control burgers (CBs). The plasma malondialdehyde concentration increased significantly in the CB group as a change from baseline (P = 0.026). There was a significant time-trend difference (P = 0.013) between the 2 groups. Urinary malondialdehyde concentrations (micromol/g creatinine) decreased by 49% (P = 0.021) in subjects consuming the SBs compared with subjects consuming the CBs.

CONCLUSIONS

The overall effect of adding the spice mixture to hamburger meat before cooking was a reduction in malondialdehyde concentrations in the meat, plasma, and urine after ingestion. Therefore, cooking hamburgers with a polyphenol-rich spice mixture can significantly decrease the concentration of malondialdehyde, which suggests potential health benefits for atherogenesis and carcinogenesis. This trial was registered at clinical trials.gov as NCT01027052.

Exposures to particulate matter and polycyclic aromatic hydrocarbons and oxidative stress in schoolchildren

BACKGROUND

Air pollution is known to contribute to respiratory and cardiovascular mortality and morbidity. Oxidative stress has been suggested as one of the main mechanisms for these effects on health.

OBJECTIVE

The aim of this study was to analyze the effects of exposure to particulate matter (PM) with aerodynamic diameters < or = 10 microm (PM10) and < or = 2.5 microm (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) on urinary malondialdehyde (MDA) levels in schoolchildren.

METHODS

The study population consisted of 120 schoolchildren. The survey and measurements were conducted in four cities--two in China (Ala Shan and Beijing) and two in Korea (Jeju and Seoul)--between 4 and 9 June 2007. We measured daily ambient levels of PM and their metal components at the selected schools during the study period. We also measured urinary 1-hydroxypyrene (1-OHP) and 2-naphthol, to assess PAH exposure, and MDA, to assess oxidative stress. Measurements were conducted once a day for 5 consecutive days. We constructed a linear mixed model after adjusting for individual variables to estimate the effects of PM and PAH on oxidative stress.

RESULTS

We found statistically significant increases in urinary MDA levels with ambient PM concentrations from the current day to the 2 previous days (p < 0.0001). Urinary 1-OHP level also showed a positive association with urinary MDA level, which was statistically significant with or without PM in the model (p < 0.05). Outdoor PM and urinary 1-OHP were synergistically associated with urinary MDA levels. Some metals bound to PM10 (aluminum, iron, strontium, magnesium, silicon, arsenic, barium, zinc, copper, and cadmium) and PM2.5 (magnesium, iron, strontium, arsenic, cadmium, zinc, aluminum, mercury, barium, and copper) also had significant associations with urinary MDA level.

CONCLUSION

Exposure to PM air pollution and PAHs was associated with oxidative stress in schoolchildren.

[Oxidative stress biomarkers determination in urine samples in the group of medical students exposed to tobacco smoke]

Cigarette smoking constitutes one of the main sources of exposure to cancerogenic and procancerogenic xenobiotics in the human population. Smoking is not only a bad habit among adults but also among young people. Despite many anti-tobacco campaigns undertaken by European Union countries still the smoking percentage among young people is high and does not decrease in the recent years. Cigarettes smoking induces formation of reactive oxygen species and increases lipids peroxidation, which ultimately results in the production of MDA (malondialdehyde)--one of the oxidative stress biomarkers. Exposure to oxidative stress and the consequences of its influence can be measured by redox parameters monitoring. One of these methods is determination of total antioxidant activity by means of FRAP test (Ferric Reducing Antioxidant Power) in biological samples. The aim of this work was the evaluation of free radical processes increase related to tobacco smoke exposure by measurement of total antioxidant activity FRAP and MDA concentration in urine samples of medical students. In our study the authors'--designed questionnaire regarding the assessment of exposure to tobacco smoke and chosen xenobiotics was used. The investigated group included 134 students of 1-st and 2-nd year of study at Faculty of Medicine and Dentistry Division in Zabrze, Silesian Medical University. 85 students provided urine samples for further analysis. In the study group 40 students were active smokers and the control group consisted of 45 nonsmokers. The mean MDA concentrations in smoking students group were higher in comparison to the control group of non-smoking students. In the group of students exposed to second-hand smoke MDA concentrations were significantly higher in comparison to the group of students non-exposed to second hand smoke. The values of FRAP parameter were significantly higher for students who smoked in comparison with students non-exposed to tobacco smoke. Students exposed to second hand smoke had slightly higher FRAP values in comparison to smoking students. Exposure to tobacco smoke increased the intensity of free radical processes. Our study confirmed the harmful influence of second hand smoke that resulted in observed higher concentrations of determined biomarkers in the group of passive smoking students.

Contribution of macrophage secretory products to urovirulence of Pseudomonas aeruginosa

Macrophages form one of the first lines of defense on mucosal surfaces like urinary tract, providing protection against pathogens. These cells pour their secretory products, which include a cocktail of biomolecules, at the site of infection. In the present investigation, the effect of macrophage secretory products (MSPs) obtained after interaction of macrophages with Pseudomonas aeruginosa on the virulence of this organism in planktonic and biofilm cell mode was assessed employing a mouse model of ascending pyelonephritis. When urinary tract infection (UTI) was established with P. aeruginosa grown in the presence of 30% MSPs, the extent of pyelonephritis was enhanced. Of the two cell forms, biofilm cells had an edge over the planktonic cells with respect to in vivo virulence. The enhanced virulence of MSP-grown P. aeruginosa may be attributed to increased production of quorum-sensing systems as well as increased adherence to uroepithelial cells and evasion of phagocytosis. The results of the present study reveal that macrophages can play a key role during the course of UTI, not only through their phagocytic activity, but also through effects mediated by their secretory products. Utilization of MSPs by P. aeruginosa can have far-reaching consequences, including chronicity and recurrence of infections caused by this pathogen.

Effects of allopurinol, a xanthine oxidase inhibitor, on renal injury in hypercholesterolemia‐induced hypertensive rats

To investigate if increased lipid peroxidation is involved in hypercholesterolemia-induced hypertension and renal injury, we examined the effects of allopurinol, a xanthine oxidase inhibitor, on these conditions. Groups of male Sprague--Dawley rats were fed for 8 weeks with a high-cholesterol diet (4% cholesterol), a high-cholesterol plus allopurinol (10 mg/kgBW/day) diet or a normal diet. Systolic blood pressure (SBP), serum lipids, uric acid (UA) and malondialdehyde (MDA) as a measure of lipid peroxides, and urinary excretion of protein (UP) were measured after 0, 4 and 8 weeks. Urinary excretion of nitrite plus nitrate (UNOx) and iron (UFe), and MDA in the kidney were measured after 8 weeks. The renal injury was evaluated by the glomerular sclerosis score (SS). The high-cholesterol diet increased SBP, serum total cholesterol and UA, MDA in the serum and kidney, UP, UNOx, UFe and SS. Allopurinol ameliorated cholesterol-induced elevation in serum UA, MDA in the serum and kidney, UP, UNOx, UFe and SS, but did not affect SBP. Hence, our results suggest that lipid peroxidation may be involved in hypercholesterolemia-induced renal injury, and that suppression of lipid peroxidation can reduce such injury.

Effect of docosahexaenoic acid and eicosapentaenoic acid supplementation on oxidative stress levels during pregnancy

Docosahexaenoic acid (DHA) is an indispensable component of cell membranes with high requirements during pregnancy. DHA supplementation is thought to enhance oxidative stress because of increased likelihood of lipid peroxidation. We estimated the oxidative stress levels in two groups of pregnant women who received daily supply of required vitamins with (n = 23) or without (n = 23) 500 mg of DHA and 150 mg of eicosapentaenoic acid (EPA) from 20 weeks of gestation to the time of delivery. Urinary excretions of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage and of malondialdehyde (MDA), a marker of lipid peroxidation, were measured at 20, 30 weeks and at the time of delivery. Urinary MDA excretion remained unchanged throughout the study period in both groups. Urinary 8-OHdG excretion at delivery was significantly higher than at 20 and 30 weeks (p < 0.05), but there were no group differences at the three time points. There were no differences between the two groups in plasma a-tocopherol levels. We conclude that under the conditions studied, a daily supplementation of 500 mg DHA and 150 mg EPA with vitamins to pregnant women did not enhance lipid peroxidation or oxidative DNA damage.

Early markers of renal injury in predicting outcome in thermal burn patients

Acute renal failure (ARF) is a well known complication of severe burn and is an important factor that can increase mortality. To determine the predictors of acute renal failure that occur in major burns, we studied 40 patients with moderate to severe thermal burn injury - second to third degree with > 20% of total body surface area. All patients were subjected to routine investigations including: Serum creatinine, blood urea nitrogen, fractional excretion of sodium, urinary malondialdehyde and microalbuminuria on day 0, 3, 7, 14 and 21 of hospitalization. Nine patients (22.5 %) developed acute renal failure; 4 patients required supportive dialysis. The group that developed ARF showed an increase of markers of glomerular damage with appearance of micro-albuminuria on day 0 that reached 3 - 4 folds above its normal level on day 14 and remained constant with elevated serum creatinine and burn size in the 3 rd week of ARF, and progressed to overt proteinuria in 3 cases. Urinary malondialdehyde increased 3 folds above normal values before developing acute renal failure, and gradually increased on day 14, which coincided with the increased of microalbuminuria. Two cases (22.2%) in the ARF group who developed septicemia and required dialysis died on the 32 nd and 36 th days post-burn. Burn size and occurrence of septicemia were the only predictors of acute renal failure using multiple regression analysis (P value < 0.001 and < 0.0371, respectively). We conclude that acute renal failure complicates burn patients and is related to the size and depth of burn and occurrence of septicemia. Microalbuminuria and urinary malondialdehyde are useful markers for prediction of renal outcome in such group of patients.

Rapid and easy method for monitoring oxidative stress markers in body fluids of patients with asbestos or silica-induced lung diseases

Sensitive assay method was developed for a parallel, rapid and precise determination of the most prominent oxidative stress biomarkers: 8-iso-prostaglandin F(2alpha), malondialdehyde and 4-hydroxynonenal. The method consisted of a pre-treatment part a solid-phase extraction, for rapid and effective isolation of biomarkers from body fluids (exhaled breath condensate, plasma and urine) and the detection method LC-ESI-MS/MS, where the selected reaction monitoring mode was used for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. The developed method was characterized by the following parameters: the imprecision was below 14.3%, the mean inaccuracy was determined to be lower than 13.1%. The method was tested on samples obtained from patients diagnosed with asbestosis, pleural hyalinosis or silicosis, i.e. occupational lung diseases caused by fibrogenic dusts, inducing oxidative stress in the respiratory system, and then compared to samples from healthy subjects. The difference in concentration levels of biomarkers between the two groups was perceptible in all the body fluids (the difference observed in an exhaled breath condensate was statistically most significant).

Lipid peroxidation in early type 1 diabetes mellitus is unassociated with oxidative damage to DNA

Oxidative stress damages DNA in experimental diabetes, and in vitro studies have suggested that it is linked to lipid peroxidation. The objective of the study was to determine whether lipid peroxidation, as assessed with malondialdehyde excretion in recent-onset type 1 diabetes mellitus, is associated with oxidative damage to DNA, as assessed from 8-hydroxydeoxyguanosine excretion. A 3-year longitudinal study of recent-onset type 1 diabetes mellitus was performed. Age- and sex-matched control subjects were studied once. Patients were studied as inpatients at West Virginia University Hospitals. Thirty-seven patients with recent-onset (2-22 months) type 1 diabetes mellitus (male, 10; female, 27) were enrolled in a longitudinal study of oxidative stress. The mean age of the patients was 20 years. None of the patients had hyperlipidemia or were treated with lipid-lowering drugs. Only 1 patient had hypertension and was being treated with beta-adrenergic blocking therapy. Thirty-six patients completed the study; one withdrew after the second evaluation. Lipid peroxidation was assessed by measuring malondialdehyde excretion. Oxidative damage to DNA was assessed from 8-hydroxydeoxyguanosine excretion. Malondialdehyde excretion was increased in the diabetic patients at the first evaluation (2.43 +/- 0.31 micromol/g creatinine), second evaluation (2.34 +/- 0.24), and third evaluation (1.93 +/- 0.15) compared with control subjects (1.51 +/- 0.11) (P < .005). 8-Hydroxydeoxyguanosine excretion, however, was not increased in the diabetic patients. There was no correlation between malondialdehyde and 8-hydroxydeoxyguanosine excretion. We confirmed the presence of oxidative stress in early diabetes as assessed from malondialdehyde excretion. We were unable, however, to confirm oxidative damage to DNA in this cohort of patients; and there was no evidence of a correlation between lipid peroxidation and DNA damage.

Arsenicosis status and urinary malondialdehyde (MDA) in people exposed to arsenic contaminated-coal in China

The current arsenic exposure condition, arsenicosis prevalence, urinary arsenic and MDA (malondialdehyde) concentrations in people were studied. The study area, a village in Xing Ren County in Guizhou Province, PR China, is a coal-borne arsenicosis endemic area that was identified several decades ago. The residents in Xing Ren have been using coal containing high arsenic levels all their life. Urinary arsenic levels of villagers were 192.2+/-22 microg/g creatinine (n=113) in the coal-borne endemic area (Xing Ren county) and were significantly higher than 63.6+/-5.9 microg/g creatinine (n=30) in a neighbouring control site (a village in Xing Yi county). The urinary MDA concentrations of villagers from the endemic area were also significantly higher compared to those of the control area. There was a strong correlation between age and urinary arsenic and MDA concentrations in the endemic area of Xing Ren; urinary arsenic and MDA levels decreased with age. Fifty out of 113 (44.3%) villagers in the endemic area had arsenicosis symptoms and the prevalence in villagers older than 40 y was 100% in male (92.2% overall). Urinary MDA concentration was significantly higher in people with arsenicosis symptoms in the endemic areas. Oxidative stress (urinary MDA concentration) was strongly related to arsenic exposure but not to the age and smoking habit. Higher urinary arsenic and MDA levels in younger villagers from the endemic area suggest that they are having a higher exposure to coal-borne emitted arsenic because they spend more time indoor. There is an urgent need to develop proper intervention methods in the Guizhou endemic areas in order to reduce the risk to the local communities who are still using arsenic contaminated-coal.

Effects of NADPH oxidase inhibitor on diabetic nephropathy in OLETF rats: the role of reducing oxidative stress in its protective property

Diabetic nephropathy is the most serious complication in diabetes mellitus. Oxidative stress via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and vascular endothelial growth factor (VEGF) pathway play critical roles in the development of diabetic nephropathy. We evaluated the effects of apocynin, NADPH oxidase inhibitor on diabetic nephropathy in a type 2 diabetic rat model. Sixteen Otsuka Long Evans Tokushima Fatty (OLETF) rats and 9 Long Evans Tokushima Otsuka (LETO) were divided into the following three groups: LETO rats (n=9), control OLETF rats (n=7) and apocynin-treated OLETF rats (n=9). We examined body weights, plasma glucose levels, urinary albumin-creatinine ratio (ACR) and protein-creatinine ratio (PCR). At 50 weeks, experimental rats were sacrificed and their kidneys were extracted for hematoxylin eosin stain, immunohistochemical VEGF stain and VEGF mRNA real-time RT-PCR. To examine oxidative stress, we checked 24h urinary 8-OHdG (8-hydroxy-2'-deoxyguanosine) and MDA (malondialdehyde). Urinary protein and albumin excretions were reduced after apocynin treatment, though apocynin could not significantly decrease serum glucose levels. There were improvements of glomerular and mesangial expansion in the apocynin-treated OLETF rats. Apocynin significantly decreased optical density of glomerular VEGF expression in immunohistochemical stain and reduced the concentration of 24h urinary 8-OHdG and MDA. From these results, it was suggested that apocynin may have the potential to protect against diabetic nephropathy via amelioration of oxidative stress.

Mycophenolate mofetil administration reduces renal inflammation, oxidative stress, and arterial pressure in rats with lead-induced hypertension

Hypertension is a likely consequence of chronic lead exposure in humans, especially in association with reduced renal function and in high risk populations. Numerous studies have demonstrated that oxidative stress plays an important role in the pathogenesis of experimental lead-induced hypertension and we have shown recently that tubulointerstitial immune cell infiltration is a feature of chronic low-dose lead exposure. Since oxidative stress, renal inflammation, and angiotensin activity are closely linked characteristics in experimental models of hypertension, we decided to investigate whether lead-induced hypertension would be ameliorated by suppressing renal inflammation with the immunosuppressive drug mycophenolate mofetil (MMF). We studied rats exposed for 14 wk to lead acetate (100 ppm in the drinking water) that, in addition, received either MMF, 20 mg.kg(-1).day(-1) by gastric gavage (Pb.MMF group, n = 12) or vehicle (Pb group, n = 12). Control rats received MMF alone (n = 5) or neither lead nor MMF (n = 6). All rats were killed at the end of the experiment. Low-dose lead exposure resulted in mild to moderate tubular cell damage and a progressive increment in blood pressure, oxidative stress, interstitial accumulation of lymphocytes and macrophages, NF-kappaB activation, and increased renal angiotensin II level. The administration of MMF suppressed the tubulointerstitial accumulation of lymphocytes and macrophages and prevented the hypertension, oxidative stress, and NF-kappaB activation and reduced the heightened renal angiotensin content associated with chronic lead exposure. We conclude that interstitial inflammation plays an important role in lead-induced hypertension.

Insulin maintains plasma antioxidant capacity at an early phase of kidney transplantation

BACKGROUND

Ischaemia-reperfusion and hyperglycaemia are two main sources of oxidative stress that plays an important role in the pathophysiology of tissue injury in transplant recipients. We hypothesized that controlling hyperglycaemia with insulin during the first hours following kidney transplantation could improve antioxidant defences and therefore decrease ischaemia-reperfusion-induced injury.

METHOD

We performed a prospective randomized study in non-diabetic dialysed patients receiving a first cadaveric renal allograft, and assigned them to receive either 200 g/day of glucose infusion (control group, n=23) or the same glucose infusion and intravenous insulin to maintain blood glucose<10 mmol/l (insulin group, n=20). Antioxidant defences were assessed by the plasma total radical-trapping antioxidant parameter (TRAP).

RESULTS

TRAP values remained stable throughout the study in the Insulin group, whereas they decreased from admission to day 1 (-2.70+/-0.16 vs -2.98+/-0.26, P<0.0001), and tended to retrieve the basal values at day 15 in the control group. TRAP values were significantly higher in the insulin group compared with the control group at days 1 (-2.80+/-0.19 vs -2.98+/-0.16, P<0.05) and 4 (-2.80+/-0.19 vs -2.95+/-0.20, P<0.05). No differences were found between the two groups on urinary malondialdehyde determination, two markers of oxidative damage, nor in graft function or patient outcome.

CONCLUSIONS

This is the first clinical trial to demonstrate improvement in insulin-induced antioxidant defences at the early stage of kidney transplantation. More extensive studies will tell if this strategy has beneficial impact in long-term graft outcome.

Lipid peroxidation in workers exposed to aluminium, gallium, indium, arsenic, and antimony in the optoelectronic industry

OBJECTIVE

The objective of this study was to investigate whether exposure to aluminum, gallium, indium, arsenic, and antimony induces lipid peroxidation in humans.

METHODS

Whole blood and urine levels of 103 exposed electronic industry workers and 67 referents were analyzed by use of inductively coupled plasma mass spectrometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography.

RESULTS

The mean plasma MDA level in the 103 workers was significantly higher than that in 67 referents. The levels of MDA in the exposed workers were correlated significantly with the levels of urinary gallium and arsenic.

CONCLUSIONS

Malondialdehyde as an index of lipid peroxidation can be induced by gallium and arsenic exposure. By reducing exposure to these metals, biologic effects such as lipid peroxidation may also be diminished.

The effect of shock wave lithotripsy on nitric oxide and malondialdehyde levels in plasma and urine samples

Shock wave lithotripsy (SWL) is accepted as the first treatment choice for most urinary stones, but it has adverse effects on the kidneys. The mechanisms underlying shock wave-induced renal injury have been discussed and include shear stress, thermal and cavitation effects and free radical formation. We investigated the effects of SWL on plasma and urinary nitrite, a stable metabolite of nitric oxide (NO), and malondialdehyde (MDA) concentrations. Between February and October 2004, 12 men and 8 women with renal calculi were treated using a Dornier MPL-9000 lithotriptor. The ages ranged from 22 to 45 years (average age: 33.7 years). Plasma and urinary NO and MDA levels were analysed before, immediately after, 30 and 60 min and 24 h after SWL. Plasma NO levels were higher than baseline levels immediately, and at 30, 60 min and 24 h after treatment (p = 0.016, p = 0.031, p = 0.033 and p = 0.045, respectively). Simultaneously, the mean urinary NO levels also showed significant elevation after SWL compared with baseline values, except for 24 h (p = 0.021, p = 0.023 and p = 0.048, respectively). The mean levels of plasma MDA showed statistically significant elevation immediately, and 30 and 60 min after SWL termination compared with pre-SWL values (p = 0.012, p = 0.008 and p = 0.012, respectively). Urinary MDA levels obtained immediately (p = 0.035), and 30 (p = 0.006) and 60 (p = 0.045) min after SWL were increased compared to pre-SWL values. We speculate that SWL treatment causes oxidative stress caused by renal ischemia-reperfusion (I/R) injury. Additionally, the increase of NO production may have prevented renal damage caused by vasoconstriction.