Protective effects of vitamins C and E on the number of micronuclei in lymphocytes in smokers and their role in ascorbate free radical formation in plasma

Cigarette smoke is widely believed to increase free radical concentrations causing subsequent oxidative processes that lead to DNA damage and hence, to several diseases including lung cancer and atherosclerosis. Vitamin C is a reducing agent that can terminate free-radical-driven oxidation by being converted to a resonance-stabilized free radical. To investigate whether short-term supplementation with the antioxidants vitamin C and E decreases free-radical-driven oxidation and thus decreases DNA damage in smokers, we determined the frequency of micronuclei in lymphocytes in 24 subjects and monitored the electron paramagnetic resonance signal of ascorbate free radical formation in plasma. Further parameters comprised sister-chromatid exchanges and thiobarbituric acid-reactive substances. Twelve smokers and twelve non-smokers took 1000 mg ascorbic acid daily for 7 days and then 1000 mg ascorbic acid and 335.5 mg RRR-alpha-tocopherol daily for the next 7 days. Baseline concentrations of both vitamins C and E were lower and baseline numbers of micronuclei were higher (p < 0.0001) in smokers than in non-smokers. After 7 days of vitamins C and E, DNA damage as monitored by the number of micronulei was decreased in both, smokers and non-smokers, but it was more decreased in smokers as indicated by fewer micronuclei in peripheral lymphocytes (p < 0.05). Concomitantly, the plasma concentrations of vitamin C (p < 0.001) as well as the ascorbate free radical (p < 0.05) were increased. The corresponding values in non-smokers, however, did not change. Our findings show that increased ascorbate free radical formation in plasma after short-term supplementation with vitamins C and E can decrease the number of micronuclei in blood lymphocytes and thus DNA damage in smokers.     

Protective effects of vitamins C and E on the number of micronuclei in lymphocytes in smokers and their role in ascorbate free radical formation in plasma

Cigarette smoke is widely believed to increase free radical concentrations causing subsequent oxidative processes that lead to DNA damage and hence, to several diseases including lung cancer and atherosclerosis. Vitamin C is a reducing agent that can terminate free-radical-driven oxidation by being converted to a resonance-stabilized free radical. To investigate whether short-term supplementation with the antioxidants vitamin C and E decreases free-radical-driven oxidation and thus decreases DNA damage in smokers, we determined the frequency of micronuclei in lymphocytes in 24 subjects and monitored the electron paramagnetic resonance signal of ascorbate free radical formation in plasma. Further parameters comprised sister-chromatid exchanges and thiobarbituric acid-reactive substances. Twelve smokers and twelve non-smokers took 1000 mg ascorbic acid daily for 7 days and then 1000 mg ascorbic acid and 335.5 mg RRR-α-tocopherol daily for the next 7 days. Baseline concentrations of both vitamins C and E were lower and baseline numbers of micronuclei were higher (p < 0.0001) in smokers than in non-smokers. After 7 days of vitamins C and E, DNA damage as monitored by the number of micronulei was decreased in both, smokers and non-smokers, but it was more decreased in smokers as indicated by fewer micronuclei in peripheral lymphocytes (p < 0.05). Concomitantly, the plasma concentrations of vitamin C (p < 0.001) as well as the ascorbate free radical (p < 0.05) were increased. The corresponding values in non-smokers, however, did not change. Our findings show that increased ascorbate free radical formation in plasma after short-term supplementation with vitamins C and E can decrease the number of micronuclei in blood lymphocytes and thus DNA damage in smokers.     

Breath alkanes as a marker of oxidative stress in different clinical conditions

We assessed oxidative stress in three different clinical conditions: smoking, human immunodeficiency virus (HIV) infection, and inflammatory bowel disease, using breath alkane output and other lipid peroxidation parameters such as plasma lipid peroxides (LPO) and malondialdehyde (MDA). Antioxidant micronutrients such as selenium, vitamin E, C, beta-carotene and carotenoids were also measured. Lipid peroxidation was significantly higher and antioxidant vitamins significantly lower in smokers compared to nonsmokers. Beta-carotene or vitamin E supplementation significantly reduced lipid peroxidation in that population. However, vitamin C supplementation had no effect. In HIV-infected subjects, lipid peroxidation parameters were also elevated and antioxidant vitamins reduced compared to seronegative controls. Vitamin E and C supplementation resulted in a significant decrease in lipid peroxidation with a trend toward a reduction in viral load. In patients with inflammatory bowel disease, breath alkane output was also significantly elevated when compared to healthy controls. A trial with vitamin E and C is underway. In conclusion, breath alkane output, plasma LPO and MDA are elevated in certain clinical conditions such as smoking, HIV infection, and inflammatory bowel disease. This is associated with lower levels of antioxidant micronutrients. Supplementation with antioxidant vitamins significantly reduced these lipid peroxidation parameters. The results suggest that these measures are good markers for lipid peroxidation.     

Increased frequency of micronuclei in B and T8 lymphocytes from smokers

The frequency of micronuclei was measured in peripheral B lymphocytes and some T lymphocyte subpopulations from 5 medium-tar cigarette smokers, and 5 non-smokers with no regular exposure to tobacco smoke. The peripheral lymphocytes were stimulated in vitro with phytohemagglutinin and B lymphocytes and the various T lymphocyte subsets were classified by a recently developed MAC (Morphology, Antibody, Chromosomes) method which allows the immunologic identification of different cell lineages. An increased frequency of micronuclei was observed in B and especially in the suppressor/cytotoxic T8 lymphocytes from smokers, as compared with non-smoker values. In non-smoker cultures, no differences in the frequency of micronuclei were observed among the different T lymphocyte subsets. In these cultures, B cells tended to have a higher frequency of micronuclei than did T cells. The proportions of B cells and the various T subpopulations among mitotic and interphasic lymphocytes from smokers and non-smokers were also determined. The proportions of B cells and T cell subsets among all mitotic lymphocytes were similar in smokers and non-smokers. Contrarily, a significant decrease in the proportion of T8 lymphocytes among all interphasic lymphocytes was observed in cultures derived from smokers.     

Impact of zinc,selenium and lycopene on capsaicin induced mutagenicity and oxidative damage in mice

Capsaicin is employed as a condiment and colorant in the cosmetic and pharmaceutical industries. Metabolism of capsaicin produces reactive phenoxy radicals, which inflict damage to DNA. Micronutrients such as zinc and selenium facilitate the expression of tissue repair factors, and lycopene has natural antioxidant action. The current study investigated the possible protective role of zinc, selenium and lycopene singly and in combination in ameliorating capsaicin induced mutagenicity. Fifty four Swiss albino mice received the vehicle, zinc (10 mg/kg), selenium (2 mg/kg), lycopene (2 mg/kg) alone, capsaicin alone (2 mg/kg), and capsaicin along with zinc (10 mg/kg), selenium (2 mg/kg) and lycopene (2 mg/kg) in combination by the oral route for 32 days. Animals were killed 24 h after the last treatment, and micronuclei formation in bone marrow and peripheral blood were assessed. Antioxidant status in plasma, the total protein, nucleic acids, and DNA fragmentation was assessed in the liver homogenate. Capsaicin substantially damaged nuclear material and increased oxidative stress. Individual therapy with lycopene was most effective in reducing micronuclei formation, lipid peroxidation, and in augmenting ferric reducing ability of plasma. This was closely followed by zinc and selenium. Zinc protected against DNA fragmentation followed by lycopene and selenium. The combination therapy was effective over individual treatment against DNA fragmentation, micronuclei and malondialdehyde formation. The combination did not exert a substantial benefit over individual therapy in enhancing the total antioxidant ability of plasma. The risk of capsaicin induced mutagenicity was lowered with the combination by reducing the generation of free radicals and by enhancing tissue repair.     

Dietary vitamin C down-regulates inflammatory gene expression in apoE4 smokers

The deleterious impact of cigarette smoking on cardiovascular health may be in part attributable to a free radical mediated proinflammatory response in circulating monocytes. In the current investigation, the impact of vitamin C supplementation on monocyte gene expression was determined in apoE4 smokers versus non-smokers. A total of 10 smokers and 11 non-smokers consumed 60mg/day of vitamin C for four weeks and a fasting blood sample was taken at baseline and post-intervention for the determination of plasma vitamin C and monocyte gene expression profiles using cDNA array and real time PCR. In apoE4 smokers, supplementation resulted in a 43% increase in plasma vitamin C concentrations. Furthermore, a number of genes were differentially expressed more than 2-fold in response to treatment, including a downregulation of the proinflammatory mediators tumor necrosis factor (TNF) beta, TNF receptor, neurotrophin-3 growth factor receptor, and monocyte chemoattractant protein 1 receptor. The study has identified a number of molecular mechanisms underlying the benefit of vitamin C supplementation in smokers.     

Vitamin E bioavailability in humans

It is important to understand factors that can influence vitamin E bioavailability, particularly in populations with increased risk of coronary heart disease such as cigarette smokers. There is also a need to clarify the bioavailability of natural and synthetic vitamin E, which is currently a subject of some controversy. Previous studies using a competitive uptake approach have found bioavailability ratios of natural:synthetic vitamin E close to 2:1, differing from the accepted biopotency ratio of 1.36:1. We used a non-competitive uptake approach to compare the plasma biokinetics of deuterated natural (RRR) and synthetic (all rac) alpha-tocopheryl acetate in smokers and non-smokers. The study was comprised of two 4-week treatments with 400 mg/d (either RRR-alpha-tocopheryl or all rac-alpha-tocopheryl acetates), with a 12-week washout period between. Prior to and after each treatment subjects underwent a 48 h biokinetic protocol with 150 mg deuterated alpha-tocopheryl acetate in either the RRR or all rac form. Smokers had a lower deuterated alpha-tocopherol AUC than did non-smokers following administration of RRR, but there was no difference following administration of all rac. The ratio RRR:all rac from AUCs and C(max) was 1.3:1 in non-smokers and 0.9:1 in smokers. Following vitamin E supplementation, deuterated tocopherol AUCs were lower in both groups. These data suggest that non-smokers and smokers differ in their handling of vitamin E, that the relative bioavailability of natural and synthetic vitamin E is close to the currently accepted biopotency ratio of 1.36:1, and that following supplementation the ability of the plasma to take up newly absorbed vitamin E is decreased.     

Cigarette smokers have decreased lymphocyte and platelet alpha-tocopherol levels and increased excretion of the gamma-tocopherol metabolite gamma-carboxyethyl-hydroxychroman (gamma-CEHC)

Cigarette smoking is associated with increased oxidative stress and increased risk of degenerative disease. As the major lipophilic antioxidant, requirements for vitamin E may be higher in smokers due to increased utilisation. In this observational study we have compared vitamin E status in smokers and non-smokers using a holistic approach by measuring plasma, erythrocyte, lymphocyte and platelet alpha- and gamma-tocopherol, as well as the specific urinary vitamin E metabolites alpha- and gamma-carboxyethyl-hydroxychroman (CEHC). Fifteen smokers (average age 27 years, smoking time 7.5 years) and non-smokers of comparable age, gender and body mass index (BMI) were recruited. Subjects completed a 7-day food diary and on the final day they provided a 24 h urine collection and a 20 ml blood sample for measurement of urinary vitamin E metabolites and total vitamin E in blood components, respectively. No significant differences were found between plasma and erythrocyte alpha- and gamma-tocopherol in smokers and non-smokers. However, smokers had significantly lower alpha-tocopherol (mean+/-SD, 1.34+/-0.31 micromol/g protein compared with 1.94+/-0.54, P = 0.001) and gamma-tocopherol (0.19+/-0.04 micromol/g protein compared with 0.26+/-0.08, P = 0.026) levels in their lymphocytes, as well as significantly lower alpha-tocopherol levels in platelets (1.09+/-0.49 micromol/g protein compared with 1.60+/-0.55, P = 0.014; gamma-tocopherol levels were similar). Interestingly smokers also had significantly higher excretion of the urinary gamma-tocopherol metabolite, gamma-CEHC (0.49+/-0.25mg/g creatinine compared with 0.32+/-0.16, P = 0.036) compared to non-smokers, while their alpha-CEHC (metabolite of alpha-tocopherol) levels were similar. There was no significant difference between plasma ascorbate, urate and F2-isoprostane levels. Therefore in this population of cigarette smokers (mean age 27 years, mean smoking duration 7.5 years), alterations to vitamin E status can be observed even without the more characteristic changes to ascorbate and F2-isoprostanes. We suggest that the measurement of lymphocyte and platelet vitamin E may represent a valuable biomarker of vitamin E status in relation to oxidative stress conditions.     

Effect of vitamin E supplementation on post-exercise plasma lipid peroxidation and blood antioxidant status in smokers: with special reference to haemoconcentration effect

The oxidative effects were investigated of exhausting exercise in smokers, and the possible protective role of 400 mg day(-1) vitamin E (Vit E) supplementation over a period of 28 days. The subjects exercised to exhaustion including concentric-eccentric contractions following maximal cycling. The haematocrit and haemoglobin, leucocyte (WBC), plasma lactic acid (La) and malondialdehyde (MDA), erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx), serum Vit E and ceruloplasmin (CER) concentrations were measured pre and post exercise. Supplementation increased Vit E concentrations 28% and 31% in the controls and the smokers, respectively. Cigarette smoking and/or Vit E supplementation did not influence plasma lipid peroxidation or the antioxidant status at rest. Exercise caused significant haemoconcentration in all groups. When the post-exercise concentrations were adjusted for haemoconcentration, a significant elevation in La concentrations due to exercise was observed in all groups. Similarly, there were significant elevations in the adjusted WBC counts in all groups except the Vit E supplemented controls. The MDA concentrations on the other hand, when adjusted for haemoconcentration, did not exhibit any difference due to exercise. Exercise did not affect the GPx and CER activities either, while causing a SOD activity loss in all groups except the Vit E supplemented non-smokers. Serum Vit E concentrations diminished significantly in all groups after exercise. Post-exercise plasma MDA and blood antioxidant concentrations were not altered by smoking. The results would suggest that plasma volume changes should always be taken into account when assessing post-exercise plasma concentrations and that smoking and exercise do not have an additional collective effect on plasma lipid peroxidation and the dose of Vit E administered was insufficient to maintain the serum concentrations after exercise.     

Selenium and GPx-1 overexpression protect mammalian cells against UV-induced DNA damage

Supplementation of the culture media of human MCF-7 breast carcinoma cells or mouse fibroblasts with low levels of selenium (30 nM) provided as sodium selenite was shown to protect these cells from ultraviolet (UV)-induced chromosome damage, as quantified by micronucleus assay. Selenium supplementation was also effective in reducing UV-induced gene mutations as measured in the lacI shuttle vector model. Protection was dependent on functional BRCA1 activity, a protein implicated in breast cancer risk and DNA damage repair. In addition, overexpression of GPx-1, a selenoprotein with antioxidant activity, also attenuated UV induced micronuclei formation in the absence of selenium supplementation. Combining selenium supplementation with GPx-1 overexpression further reduced UV-induced micronucleus frequency. These data provide evidence that the benefits of selenium supplementation might be either through the prevention or repair of DNA damage, and they implicate at least one selenoprotein (GPx-1) in the process.     

Effects of exogenous vitamin E supplementation on the levels of oxidants and antioxidants in chronic obstructive pulmonary disease

Oxidative stress has been recognized as a central feature of smoke induced chronic obstructive pulmonary disease (COPD). Imbalance between oxidant and antioxidant enzymes is also an established fact in these patients. But studies in regard to stable COPD patients and effect of vitamin E supplementation are lacking. Thirty patients with COPD were included in the study. Their baseline clinical examination, spirometry, plasma malondialdehyde (MDA), alpha-tocopherol and red blood cell superoxide dismutase (SOD) levels were mea sured. Twenty healthy non-smokers who were matched for age and sex served as controls. All the above parameters were repeated after 12 weeks of supplementation with 400 IU of vitamin E daily. The mean malondialdehyde levels in the patients at baseline were higher than controls (5.91 +/- 1.23 nmol/ml vs 4.55 +/- 1.51 nmol/ml, P = 0 001), so also was plasma alpha-tocopherol levels (P < 0 001), while SOD levels were lower in the patients compared to controls (1692 +/- 259 units g/Hb vs 2451 +/- 131 units g/Hb, P < 0 001). Exogenous vitamin E (400 IU per day) supplementation did not bring about any significant change in plasma alpha-tocopherol and SOD levels. The Pearson s co-efficient of correlation between the levels of MDA, vitamin E, SOD; and spirometric measurements were not significant either on day 1 or after 12 weeks of vitamin E supplementation. The present study shows that initially the plasma lipid peroxide (MDA) levels are high and antioxidants (alpha-tocopherol and SOD) are low in patients with COPD. Exogenous supplementation with vitamin E does not have any significant effect on the spirometric measurements though it brings down the levels of MDA showing attenuation of further damage. However, inclusion of larger number of patients and supple mentation with vitamin E for longer periods may throw more light on free radical injury and protective effects of antioxidants.     

Effect of vitamin E supplementation on diabetes induced oxidative stress in experimental diabetes in rats

Diabetes induced by streptozotocin (50 mg/kg body wt, i.p.) in the rats substantially increased the plasma glucose and malondialdehyde levels along with corresponding decrease in the antioxidants levels. Supplementation of vitamin E (200 mg/kg body wt., ip) for 5 weeks resulted in non-significant decrease in the blood glucose levels but plasma malondialdehyde levels were reduced to below normal levels. Plasma vitamin E, vitamin C, uric acid and red blood cell glutathione levels were also restored to near normal levels on vitamin E supplementation to diabetic rats as compared to control (diabetic) rats. The activities of antioxidant enzymes, catalase (EC 1.11.1.6), glutathione peroxidase (GSHPx EC 1.11.1.9), and glutathione reductase (GR EC 1.6.4.2) were also concomitantly restored to near normal levels by vitamin E supplementation to diabetic rats. The results clearly demonstrated that vitamin E supplementation augments the antioxidant defense mechanism in diabetes and provides evidence that vitamin E may have a therapeutic role in free radical mediated diseases.     

Effects of oral vitamin C on monocyte: endothelial cell adhesion in healthy subjects

Monocyte recruitment and retention in the vasculature is influenced by oxidative stress and is involved in cardiovascular disease (CVD). Individuals with low plasma ascorbate are at elevated risk of CVD. It is unknown whether vitamin C supplementation affects monocyte adhesion to endothelial cells (ECs) in healthy non-smokers. In a randomised double-blind crossover study the effect of vitamin C supplementation (six weeks, 250 mg/day) was determined in subjects with normal (HIC) and below average (LOC) plasma vitamin C concentration at baseline (mean=67 microM, n=20, mean=32 microM, n=20, respectively). LOC subjects showed 30% greater monocyte adhesion to ECs. This was significantly reduced by 37% (P<0.02) following vitamin C supplementation to levels of HIC monocyte adhesion. No differences in plasma malondialdehyde concentrations were observed between groups or after supplementation. In conclusion, vitamin C supplementation normalises monocyte adhesion in subjects with low plasma vitamin C (LOC). This process may be related to a direct effect on monocytes, independent of lipid peroxidation.     

Cytogenetic monitoring of a group of Italian floriculturists: no evidence of DNA damage related to pesticide exposure

The induction of sister chromatid exchanges (SCE), structural chromosome aberrations (CA) or micronuclei (MN) was investigated in peripheral lymphocytes of a group of Italian floriculturists exposed to a mixture of pesticides. No statistically significant difference in the frequencies of cytogenetic damage was detected between exposed and control subjects. Assessment of the effect of confounding factors indicated that smoking affected both SCE and CA frequencies. Multiple regression analysis showed that in heavy smokers (≥ 20 cigarettes/day), SCE and CA levels increased significantly by 17% and 54%, respectively, as compared to non-smokers.     

Vitamin C for DNA damage prevention

The ability of vitamin C to affect genetic damage was reviewed in human studies that used molecular epidemiology methods, including analysis of DNA adducts, DNA strand breakage (using the Comet assay), oxidative damage measured as levels of 8-oxo-7,8-dihydroxy-2'-deoxyguanosine (8-oxodG), cytogenetic analysis of chromosomal aberrations and micronuclei, and the induction of DNA repair proteins. The protective effect of vitamin C was observed at plasma levels>50μmol/l. Vitamin C supplementation decreased the frequency of chromosomal aberrations in groups with insufficient dietary intake who were occupationally exposed to mutagens, and also decreased the sensitivity to mutagens as assessed using the bleomycin assay. High vitamin C levels in plasma decreased the frequency of genomic translocations in groups exposed to ionizing radiation or c-PAHs in polluted air. The frequency of micronuclei was decreased by vitamin C supplementation in smokers challenged with γ-irradiation, and higher vitamin C levels in plasma counteracted the damage induced by air pollution. The prevalence of DNA adducts inversely correlated with vitamin C levels in groups environmentally exposed to high concentrations of c-PAHs. Increased vitamin C levels decreased DNA strand breakage induced by air pollution. Oxidative damage (8-oxodG levels) was decreased by vitamin C supplementation in groups with plasma levels>50μmol/l exposed to PM2.5 and c-PAHs. Modulation of DNA repair by vitamin C supplementation was observed both in poorly nourished subjects and in groups with vitamin C plasma levels>50μmol/l exposed to higher concentrations of c-PAHs. It is possible that the impact of vitamin C on DNA damage depends both on background values of vitamin C in the individual as well as on the level of exposure to xenobiotics or oxidative stress.     

Age-dependent inclusion of sex chromosomes in lymphocyte micronuclei of man.

Two-color centromeric FISH was used to study the inclusion of the X and Y chromosomes in micronuclei of cultured lymphocytes from 10 men representing two age groups (21-29 years and 51-55 years). In addition, pancentromeric FISH was separately performed to identify any human chromosomes in micronuclei. One hundred micronuclei per probe were examined from each donor. A higher mean frequency of Y-positive micronuclei was observed in the older men than in the younger men. In both age groups, the X chromosome was micronucleated clearly more often than expected by chance, and the Y chromosome was overrepresented in micronuclei among the older men but not among the younger men. In lymphocytes of four women, X-positive micronuclei were more frequent than they were in men, even after the fact that women have two X chromosomes was taken into account. Similar results were obtained in first-division lymphocytes identified by cytochalasin-B-induced cytokinesis block. In comparison with normal cells, these binucleate cells showed a higher frequency (per 1,000 nuclei) of X-positive micronuclei (in the older men) but a lower frequency of micronuclei harboring autosomes or acentric fragments. In conclusion, the results show that both the X chromosome and the Y chromosome are preferentially micronucleated in male lymphocytes, the Y chromosome only in older subjects. Although the X chromosome has a general tendency to be included in micronuclei, it is micronucleated much more often in women than in men, which is probably the main reason for the high micronucleus frequency in women that has been documented in many previous studies.     

Factors contributing to chromosome damage in lymphocytes of cigarette smokers

Cigarette smoking is generally believed to be responsible for a substantial number of human health problems. However, the causal relationship between smoking, the induction of biological effects and the extent of health problems among smokers have not been fully documented. Using the recently developed lymphocyte micronucleus (MN) assay, we have evaluated the chromosome aberration frequencies in 67 cigarette smokers and 59 matched non-smoking control subjects. We found that the mean MN frequency (per 100 cells) in the smokers was slightly higher than that found in the non-smokers (0.71 +/- 0.23 and 0.58 +/- 0.05 respectively; p less than 0.08). Factors which contribute to the expression of chromosome aberrations were also investigated. A significant age-dependent increase in MN frequencies was observed in both groups (p less than 0.05). Linear regression analysis showed that the age-dependent effects among smokers (r = 0.54; p less than 0.02) was further enhanced by cigarette consumption (r = 0.62; p less than 0.005). Consumption of low potency 'one-a-day' type multivitamins had no effect on MN frequencies in either sex of non-smokers and in the 1 male smoker who took multivitamins but vitamin intake consistently reduced the MN frequencies among female smokers. Using a challenge assay, fidelity of DNA repair was evaluated. Lymphocytes from both smokers and non-smokers were irradiated with single doses of 0 or 100 cGy of X-rays or with double doses of 100 cGy of X-rays each separated by 15 or 60 min (100/15 or 100/60). Chromosome translocation frequencies were consistently higher after irradiation in lymphocytes from smokers than in those from non-smokers. Statistically significant differences were detected when the cells were irradiated with the double doses of 100 cGy X-rays each separated by 60 min (p less than 0.05). These data suggest that lymphocytes from smokers made more mistakes in the repair of DNA damage than cells from non-smokers. Our studies provide new insights into the genotoxic effects of cigarette smoke and new information which may be useful for understanding the mechanisms for induction of health problems from smoking.     

Leather tanning workers: chromosomal aberrations in peripheral lymphocytes and micronuclei in exfoliated cells in urine

A cytogenetic study was performed on workers of a leather tanning industry. Two different approaches for the biological monitoring of the individuals were used: chromosomal aberration analysis in peripheral lymphocytes and the frequency of micronucleated cells exfoliated in urine samples. 26 men working in the sections considered to present a greater risk were included in the study. Controls were 20 men that were not exposed to chemicals. The percentage of abnormal cells was higher in workers than in controls. Smokers showed higher values of chromosome breaks than non-smokers in both groups. These differences were not statistically significant. The percentage of cells with chromatid and chromosome gaps in workers and controls was different (p less than 0.01). A slight but not significant increase in the mean percentage of micronuclei was observed in the exposed group. We conclude that exposure to chemicals during leather tanning did not produce genotoxic effects measured by chromosomal aberrations in peripheral lymphocytes and micronuclei in urine in this group of workers.     

Vitamin C supplementation lowers urinary levels of 4-hydroperoxy-2-nonenal metabolites in humans

The lack of suitable biomarkers of oxidative stress is a common problem for antioxidant intervention studies in humans. We evaluated the efficacy of vitamin C supplementation in decreasing biomarkers of lipid peroxidation in nonsmokers and in cigarette smokers, a commonly studied, free-living human model of chronic oxidative stress. Participants received ascorbic acid (500mg twice per day) or placebo for 17 days in a double-blind, placebo-controlled, randomized crossover design study. The urinary biomarkers assessed and reported herein are derived from 4-hydroperoxy-2-nonenal (HPNE) and include the mercapturic acid (MA) conjugates of 4-hydroxy-2(E)-nonenal (HNE), 1,4-dihydroxy-2(E)-nonene (DHN), and 4-oxo-2(E)-nonenol(ONO). Vitamin C supplementation decreased the urinary concentrations of both ONO-MA (p=0.0013) and HNE-MA (p=0.0213) by ~30%; however, neither cigarette smoking nor sex affected these biomarkers. In contrast, vitamin C supplementation decreased urinary concentrations of DHN-MA (three-way interaction p=0.0304) in nonsmoking men compared with nonsmoking women (p<0.05), as well as in nonsmoking men compared with smoking men (p<0.05). Vitamin C supplementation also decreased (p=0.0092) urinary total of metabolites by ~20%. Thus, HPNE metabolites can be reduced favorably in response to improved plasma ascorbic acid concentrations, an effect due to ascorbic acid antioxidant function.     

Comparison of whole blood selenium values and erythrocyte glutathione peroxidase activities of normal individuals on supplementation with selenate,selenite,l-selenomethionine,and high selenium yeast

The selenium levels and the glutathione peroxidase activity GSH-PX of whole blood and of erythrocytes, respectively, were determined in 139 normal Danes and related to sex and smoking habits. No differences were found in relation to sex apart from a higher GSH-PX activity of females when assayed with tertiary butyl hydroperoxide. Smokers showed significantly lower selenium values than non-smokers (p<0.05), but the two groups had identical GSH-PX activities. Individuals from the above-mentioned group were divided into four groups, receiving daily oral doses of 200 μg of selenium in the form of selenite, selenate, L-selenomethionine, and selenium as contained in yeast. Whole blood selenium values and the erythrocyte glutathione peroxidase activities were determined during three months of supplementation followed by a withdrawal period of four months. Both the inorganic selenium compounds and the organic derivatives gave rise to steady state levels of GSH-PX after one month of supplementation. However, the selenium levels in the groups receiving organic selenium showed a steady rise during the whole period, whereas those supplemented with inorganic selenium leveled off after a period of one to three months. The data for smokers and non-smokers revealed identical results when organic selenium was supplemented. However, selenite gave rise to significantly higher selenium levels and GSH-PX activities in smokers than in non-smokers. Less significant (p<0.08) elevations of both parameters were also observed among the smokers in the selenate group. By taking both the selenium level and the GSH-PX activity into consideration, organic selenium (i.e.,l-(+) selenomethionine) was judged to be more bioavailable than selenite and selenate.