DNA Damage Index Research Articles

Markers of genotoxicity and oxidative stress in farmers exposed to pesticides

The effects of chronic exposure to pesticides can lead to the development of several diseases, including different types of cancer, since the genotoxic and mutagenic capacity of these substances can be observed. The objective of this study is to investigate the relation between the occupational exposure to various pesticides and the presence of DNA damage and oxidative stress. Blood samples from 50 rural workers (41 men and 9 women) exposed to pesticides, 46 controls (20 men and 26 women) from the same city (Antônio Carlos, Santa Catarina state, Brazil) and 29 controls (15 men and 14 women) from another city (Florianópolis, Santa Catarina state, Brazil), were evaluated using the comet assay and the cytokinesis-block micronucleus (CBMN) technique for genetic damage, and the test of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity for the oxidative stress. Cholinesterase activities were also determined, but there was no statistical difference among exposed workers and controls. Significant differences were found in DNA damage among groups. The comet assay performed on peripheral blood lymphocytes of these individuals had a significantly higher DNA damage index in the exposed group comparing to controls (p < 0.0001). MNi (p < 0.001), NBUDs (p < 0.005) and NPBs (p < 0.0001) were also found to be significantly higher in the exposed group. The TBARS values were significantly higher comparing to the Florianopolis control group (p < 0.0001). Even though CAT values were higher than controls, there was no statistical difference. Thus, it is concluded that the exposed individuals, participants of this study, are more subject to suffer genetic damage and, consequently, more susceptible to diseases resulting from such damages.

Neonatal, placental, and umbilical cord blood parameters in pregnant women residing in areas with intensive pesticide application.

In rural populations, the proximity to areas with intensive pesticide application represents a risk factor of xenobiotic exposure. Here, we investigated whether newborns born to mothers residing in an area with intensive pesticide application show alterations in placental and neonatal morphometric standards, umbilical cord blood (UCB) biochemical parameters, and/or biomarkers related to oxidative stress and oxidative damage. Samples were collected from 151 healthy pregnant women residing in a rural area (rural group; RG) during the pesticide spraying (SS) and nonspraying (NSS) seasons, as well as from women from an urban population (control group; CG), and grouped according to the delivery type (vaginal or cesarean). In the vaginal delivery group, the placental weight and placental index were higher in the RG groups than in the CG (p=0.01), whereas in the cesarean delivery group, newborn weight was lower in the RG-SS group than in the CG. In the RG-SS group, UCB erythrocyte osmotic fragility and the DNA damage index (DI) were higher, and superoxide dismutase (SOD) activity was lower than in the RG-NSS group. Acetylcholinesterase and SOD activities were found to be inversely correlated with the DI.

A reduction in DNA damage in neural tissue and peripheral blood of old mice treated with caffeine

ABSTRACTStudies on caffeine consumption have shown a negative correlation with development of some diseases with subsequent beneficial manifestations. Our aim was to assess the effects of caffeine on peripheral blood and neural tissue DNA in young adult and aged mice. Male Swiss mice (age 2–3 or 16–18 months, respectively) were treated with a caffeine solution (0.3 g/l) for 4 weeks, while controls received water. After the treatments, blood and hippocampal cells (for a comet assay) and femurs (for a micronucleus [MN] test) were collected. The comet assay of peripheral blood and hippocampal cells demonstrated no significant differences between caffeine-treated and control young adult mice in terms of DNA damage index (DI) and frequency. In contrast, when comparing young adult with aged animals, significant differences were observed in DNA damage in blood and hippocampal cells. The differences between aged animals (with or without caffeine) consisted of a significant decrease in DNA DI in the group that received caffeine. In the MN test, an increase in frequency of micronucleated polychromatic (PCE) erythrocytes was noted in aged animals that received water compared to young adult mice. In addition, comparing treated with control aged murine groups, a decrease in frequency of MN was found in PCE erythrocytes of caffeine-treated mice. Chronic caffeine consumption was neither genotoxic nor mutagenic at the dose tested; however, it appears that caffeine actually protected mice from genotoxicity and mutagenicity, consequences attributed to aging.

Altered development, oxidative stress and DNA damage in Leptodactylus chaquensis (Anura: Leptodactylidae) larvae exposed to poultry litter

Poultry litter (PL), which is usually used as organic fertilizer, is a source of nutrients, metals, veterinary pharmaceuticals and bacterial pathogens, which, through runoff, may end up in the nearest aquatic ecosystems. In this study, Leptodactylus chaquensis at different development stages (eggs, larval stages 28 and 31 here referred to as stages I, II and III respectively) were exposed to PL test sediments as follows: 6.25% (T1), 12.5% (T2); 25% (T3); 50% (T4); 75% (T5); 100% PL (T6) and to dechlorinated water as control. Larval survival, development endpoints (growth rate -GR-, development rate -DR-, abnormalities), antioxidant enzyme activities (Catalase -CAT- and Glutathione-S-Transferase -GST-), and genotoxic effect (DNA damage index by the Comet assay) were analyzed at different times. In stage I, no egg eclosion was observed in treatments T3-T6, and 50% of embryo mortality was recorded after 24h of exposure to T2. In stages II and III, mortality in treatments T3-T6 reached 100% between 24 and 48h. In the three development stages evaluated, the DR and GR were higher in controls than in PL treatments (T1, T2), except for those T1-treated larvae of stage II. Larvae of stage I showed five types of morphological abnormalities, being diamond body shape and lateral displacement of the intestine the most prevalent in T1, whereas larvae of stages II and III presented lower prevalence of abnormalities. In stage I, CAT activity was similar to that of control (p>0.05), whereas it was higher in T1- and T2- treated larvae of stages II and III than controls (p<0.05). In stages I and III, GST activity was similar to that of controls (p>0.05), whereas it was inhibited in T1-treated larvae of stage II (p<0.05). T1- and T2-treated larvae of stages II and III caused higher DNA damage respect to controls (p<0.05), varying from medium to severe damage (comet types II, III and IV). These results showed that PL treatments altered development and growth and induced oxidative stress and DNA damage, resulting ecotoxic for L. chaquensis larvae.

Safety assessment and antioxidant activity of Lantana montevidensis leaves: Contribution to its phytochemical and pharmacological activity.

Lantana camara, the widely studied species, and L. montevidensis, the less studied species of the genus Lantana are both used in traditional medicine for the same purpose (anti-asthma, anti-ulcer, anti-tumor, etc). However, little is known about the toxicity of L. montevidensis and there is limited information on its chemical constituents. Here, we investigated for the first time the genotoxicity and cytotoxicity of the ethanolic (EtOH) and aqueous extracts from the leaves of Lantana montevidensis in human leukocytes, as well as their possible interaction with human erythrocyte membranes in vitro. The antioxidant activities of both extracts were also investigated in chemical and biological models. Treatment of leukocytes with EtOH or aqueous extracts (1-480 µg/mL) did not affect DNA damage index, but promoted cytotoxicity at higher concentrations (240-480 µg/mL). Both extracts did not modify the osmotic fragility of human erythrocytes. The extracts scavenged DPPH radical and prevented Fe2+-induced lipid peroxidation in rat's brain and liver homogenates, and this was likely not attributed to Fe (II) chelation. The HPLC analysis of the extracts showed different amounts of polyphenolic compounds (isoquercitrin, gallic acid, catechin, ellagic acid, apigenin, kaempferol, caffeic acid, rutin, quercitrin, quercetin, chlorogenic acid, luteolin) that may have contributed to these effects. These results supported information on the functional use of L. montevidensis in folk medicine.

Omega-3 fatty acid supplementation decreases DNA damage in brain of rats subjected to a chemically induced chronic model of Tyrosinemia type II.

Tyrosinemia type II is an inborn error of metabolism caused by a mutation in a gene encoding the enzyme tyrosine aminotransferase leading to an accumulation of tyrosine in the body, and is associated with neurologic and development difficulties in numerous patients. Because the accumulation of tyrosine promotes oxidative stress and DNA damage, the main aim of this study was to investigate the possible antioxidant and neuroprotective effects of omega-3 treatment in a chemically-induced model of Tyrosinemia type II in hippocampus, striatum and cerebral cortex of rats. Our results showed chronic administration of L-tyrosine increased the frequency and the index of DNA damage, as well as the 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the hippocampus, striatum and cerebral cortex. Moreover, omega-3 fatty acid treatment totally prevented increased DNA damage in the striatum and hippocampus, and partially prevented in the cerebral cortex, whereas the increase in 8-OHdG levels was totally prevented by omega-3 fatty acid treatment in hippocampus, striatum and cerebral cortex. In conclusion, the present study demonstrated that the main accumulating metabolite in Tyrosinemia type II induce DNA damage in hippocampus, striatum and cerebral cortex, possibly mediated by free radical production, and the supplementation with omega-3 fatty acids was able to prevent this damage, suggesting that could be involved in the prevention of oxidative damage to DNA in this disease. Thus, omega-3 fatty acids supplementation to Tyrosinemia type II patients may represent a new therapeutic approach and a possible adjuvant to the curren t treatment of this disease.

Apoptosis mediated chemosensitization of tumor cells to 5-fluorouracil on supplementation of fish oil in experimental colon carcinoma.

5-Fluorouracil has been considered as a cornerstone therapy for colorectal cancer; however, it suffers from low therapeutic response rate and severe side effects. Therefore, there is an urgent need to increase the clinical efficacy of 5-fluorouracil. Recently, fish oil rich in n-3 polyunsaturated fatty acids has been reported to chemosensitize tumor cells to anti-cancer drugs. This study is designed to understand the underlying mechanisms of synergistic effect of fish oil and 5-fluorouracil by evaluation of tumor cell-associated markers such as apoptosis and DNA damage. The colon cancer was developed by administration of N,N-dimethylhydrazine dihydrochloride and dextran sulfate sodium salt. Further these animals were treated with 5-fluorouracil, fish oil, or a combination of both. In carcinogen-treated animals, a decrease in DNA damage and apoptotic index was observed. There was also a decrease in the expression of Fas, FasL, caspase 8, and Bax, and an increase in Bcl-2. In contrast, administration of 5-fluorouracil and fish oil as an adjuvant increased both DNA damage and apoptotic index by activation of both extrinsic and intrinsic apoptotic pathways as compared to the other groups. The increased pro-apoptotic effect by synergism of 5-fluorouracil and fish oil may be attributed to the incorporation of n-3 polyunsaturated fatty acids in membrane, which alters membrane fluidity in cancer cells. In conclusion, this study highlights that the induction of apoptotic pathway by fish oil may increase the susceptibility of tumors to chemotherapeutic regimens.

Pesticide metabolite and oxidative stress in male farmers exposed to pesticide

BackgroundThe objective of this study was to measure malondialdehyde (MDA) and isoprostane which has been used as an index of lipid injury, 8-hydroxy-2′-deoxyguanosine (8-OHdG), which has been used as an index of DNA damage, and dialkyl-phosphate (DAP), which has been used to quantify pesticide exposure, and to investigate the relationship between pesticide exposure and oxidative stress.MethodsThis study was a cross-sectional study that evaluated 84 male farmers exposure to pesticide. In this study, 8-OHdG, isoprostane, and MDA were measured as oxidative stress indices, and dialkyl-phosphate (dimethylphosphate(DMP), diethylphosphate(DEP), dimethylthiophosphate(DMTP), and diethylthiophosphate (DETP)) excreted in the urine was also measured to evaluate pesticide exposure. A linear regression analysis was performed to investigate the relationship between pesticide metabolites, and oxidative stress biomarkers.ResultsA Correlation analysis was performed for pesticide exposure month (PEI), cumulative exposure index (CEI), and DAP as well as the concentration of the oxidative stress biomarkers. The PEM significantly and positively correlated to the levels of 8-OHdG, isoprostane, CEI, and DMP. CEI showed a correlation to 8-OHdG and PEM. DMP, DEP, and DETP showed a positive correlation to 8-OHdG, isoprostane, and MDA. A correlation analysis was adjusted some demographic characteristics, such as age, smoking, drinking, and exercise to determine the relationship between pesticide exposure and oxidative stress. The 8-OHdG, isoprostane, and MDA levels were significantly related to the DMP (ß = 0.320), DEP (ß = 0.390), and DETP (ß = 0.082); DMP (ß = 0.396), DEP (ß = 0.508), and DETP (ß = 0.504); and DMP (ß = 0.432), DEP (ß = 0.508), and DETP (ß = 0.329) levels, respectively.ConclusionsThe concentration between oxidative stress biomarkers and the pesticide metabolite were a positive correlation. Indicators of oxidative stress was associated with a pesticide metabolite DMP, DEP, and DETP. Therefore, Pesticide exposure and oxidative stress were relevant.

Short-term, supra-physiological rhGH administration induces transient DNA damage in peripheral lymphocytes of healthy women.

While a good safety for recombinant human growth hormone (rhGH) therapy at replacement doses is recognized, a possible link between high concentration of the GH-IGF-I axis hormones and side negative effect has been reported. The aim of this pilot study was to assess whether a short-term exposure to supra-physiological doses of rhGH may affect DNA integrity in human lymphocytes (PBL). Eighteen healthy Caucasian female (24.2 ± 3.5 years) were randomly included in a Control (n = 9) and rhGH administration group (n = 9, 3-week treatment). DNA damage (comet assay), chromosomal breaks, and mitotic index in phytohemagglutinin-stimulated PBL were evaluated before (PRE), immediately (POST), and 30 days (POST30) after the last rhGH administration (0.029 mgkg- 1 BW; 6 days/week), together with serum IGF-1 and IGFBP-3 concentrations. rhGH administration increased IGF-I, without evidence of persisting IGF-I and IGFBP-3 changes 30 days after withdrawal. Total DNA breakage (% DNA in tails) was not significantly different in subjects treated with rhGH in comparison with controls, although the rhGH-treated subjects showed an higher percentage of heavily damaged nuclei immediately after the treatment (POST30 vs. PRE: p = 0.003), with a lower mitogenic potential of lymphocytes, detectable up to the POST30 (PRE vs. POST: p = 0.02; PRE vs. POST30: p = 0.007). This pilot study showed that 3 weeks of short-term supra-physiological rhGH administration in healthy women induce a transient DNA damage and mitogenic impairment in PBL. The analysis of DNA damage should be explored as useful tool in monitoring the mid to long-term effects of high rhGH treatment or abuse.

THE EFFECT OF OF POLY(ADP-RIBOSE) POLYMERASE INHIBITOR 4-HYDROXY-QUINAZOLINE ON DEATH OF IMMUNE CELLS UNDER IMMUNE COMPLEX-MEDIATED INJURY IN MICE

The influence of poly(ADP-ribose) polymerase (PARP) in- hibitor 4-hydroxyquinazoline (4-HQ) on the level of DNA damage and on the death of thymic and lymph node cells in mouse model of immune complex injury was investigated to reveal its possible cytoprotective effect. As shown by comet assay, DNA damage index of immune cells was increased 4,0 times in mice with immune complex-mediated pathology induced by a long-term immunization of CBA mice with bovine serum albumin (BSA), P<0,001. The percentage of thymic cells with strong DNA damage was increased to 77% under immunization (compared to 1,5% in control mice) and the percentage of such cells from lymph nodes was increased to 80% (compared to 0% in control), in both cases P< 0,001. Genotoxic stress was reduced by treatment of immunized mice with 4-HQ: the percentage of lymphocytes with strong DNA damage was significantly decreased that promoted increase in the amount of cells having intact DNA. PARP inhibition exerted a strong cytoprotective effect: viability of thymus and lymph node cells was increased mainly due to reduced level of necrosis. So, our results suggest that PARP may be involved in thymic and lymph node cell damage in immune complex mediated pathology and give evidence that inhibition of this enzyme may constitute a perspective target in immune complex diseases prevention and therapy.

Comparative study of the cytotoxicity and genotoxicity of kaurenoic acid and its semi-synthetic derivatives methoxy kaurenoic acid and kaurenol in CHO-K1 cells

The diterpene kaurenoic acid (KA) has vasorelaxant, antimicrobial, anti-tumoural and anti-leishmanial effects. Semi-synthetic derivatives were obtained to achieve more satisfactory responses. The assessment of genotoxicity is part of the toxicological evaluation of therapeutic compound candidates. The present study investigated the cytotoxicity and genotoxicity of KA and its semi-synthetic derivatives methoxy kaurenoic acid (MKA) and kaurenol (KRN) using the CHO-K1 cell line. The cytotoxicity evaluation demonstrated that treatments with 200 and 400 μM KA reduced cellular proliferation to 36.5 and 4.43%, respectively, and that 100 and 200 μM KA reduced the survival fraction (SF) to 48.1 and 5.5%, respectively. MKA and KRN at concentrations of 400 μM reduced proliferation to 81 and 86.8%, respectively, while 100 and 200 μM KRN reduced the SF to 50%, and 200 μM MKA reduced the SF to 74%. No genotoxicity was observed for KA or MKA. However, 100 μM KRN increased the DNA damage index, as detected by comet assay, although a micronucleus assay did not confirm these data. The results demonstrated that KA and its semi-synthetic derivative MKA were not genotoxic when tested at noncytotoxic concentrations, but KRN was genotoxic at the highest concentration that was tested, as demonstrated by the comet assay.

DNA damage and postural balance in multiple sclerosis patients

Abstract Introduction: Multiple Sclerosis (MS) is a chronic inflammatory disease characterized by infiltration of inflammatory cells on the Central Nervous System (CNS). There is evidence that cumulative DNA damage can contribute to various mechanisms underlying MS lesions. Changes in postural balance are frequent observations in subjects with MS. Objective: Evaluated the DNA damage index (DDI)) and postural balance in patients with MS. Methods: A case-control study was conducted with 28 subjects matched for sex, age, and body mass index, divided into MS group and control. The DDI was assessed by comet assay and postural balance through recording the body oscillations of the center of pressure (COP), in the anterior-posterior and lateral middle directions. Results: Showed higher DDI in MS patients (21.3 ± 4.8) than controls (7.9 ± 6.1). Significant differences between groups were also noted in postural control parameters. The wider ranges of postural sway were observed in the MS group. The associations between DDI and postural control parameters showed weak, but significant correlations. No associations were found between DDI and time of diagnosis of MS. Conclusion: People with MS had higher DDI and larger body oscillations than healthy individuals.

Biological Activities and Cytotoxicity of Eperua oleifera Ducke Oil-resin.

Background:The oil-resin of Eperua oleifera Ducke has been used in popular medicine similarly to the copaiba oil (Copaifera spp.).Objective:This study aimed to investigate the effects of the acid fraction of E. oleifera oil-resin (AFEOR) on cell proliferation, collagen production in human fibroblasts, inhibition of metalloproteinases, and cytotoxicity against tumor cell lines.Materials and Methods:Acid fraction of E. oleifera was fractionated in the ion exchange column chromatography. Cytotoxicity and genotoxicity were evaluated by Alamar Blue® and Cometa assay. The inhibition of metalloproteinases was performed by zymography and Western blotting.Results:The predominant acidic diterpenes in the AFEOR were copalic and hardwickiic acids. AFEOR caused morphology alteration and decrease of proliferation at concentrations higher than 5 μg/mL. It also caused significant collagen proliferation in fibroblasts. It showed cytotoxicity against tumoral and nontumoral cell lines, with IC50 values ranging from 13 to 50 μg/mL, and a hemolytic activity with an IC50 value of 38.29 μg/mL. AFEOR inhibited collagenase activity, with an IC50 value of 46.64 μg/mL, and matrix metalloproteinase-2 (MMP)-2 and MMP-9 in HaCaT cells or MMP-1 expression in MRC-5 cells. AFEOR induced genotoxicity in MRC-5 cells with a DNA damage index between 40% and 60% when compared to the negative controls (0%–20%).Conclusion:For the first time, biological activities from oil-resin E. oleifera demonstrated ratifying somehow its popular use.SUMMARY Analysis of crude oil-resin and fractionation of diterpenic fraction was performance using selective ion-exchange column chromatographyCytotoxicity analysis and morphology were performed with different cell linesCollagen production in human fibroblasts, inhibition of metalloproteinases were demonstrated by zymography and Western blotting. Abbreviations used: AFEOR: Eperua oleifera oil-resin.

&lt;b&gt;Cd, Cu, and Mn from Uruguay River Basin in Uruguaiana, RS, Brazil, and their toxicological potential for human leukocyte

This study assessed the limnology from the Medium Uruguay River Basin in Uruguaiana, Brazil, with a focus on the concentration of heavy metals (Cd, Cu, and Mn), to assess the toxicological potential (cytotoxicity and genotoxicity) for humans using as biological matrix of study human leukocyte cells. The conductivity, resistivity, and dissolved O 2 levels exceeded the limits recommended by the National Environmental Council ( Conselho Nacional do Meio Ambiente - CONAMA). The percentage of non-viable human leukocyte cells exposed to water samples was approximately 20% higher than that of the negative control (<3%), but similar to the positive control. The DNA damage index was high for all heavy metal concentrations assayed when compared to the negative control 12±2.96, p < 0.0001, with a range of 155.66±23.89 to 194.33±23.23, but similar to the positive control (210.62±27.48). Moreover, the leukocyte degeneration index was higher in all samples containing heavy metals than in the negative control (4%), which demonstrates to be due the presence of Cu (11.8-12.5%), Cd (13-15.6%), and Mn (15.6-22.5%). Taken together, our results show that the quality from water samples analyzed is below than recommended by CONAMA and offers risk of contamination by heavy metals for the general population.

Effects of crude hydroalcoholic extract of Syzygium cumini (L.) Skeels leaves and continuous aerobic training in rats with diabetes induced by a high-fat diet and low doses of streptozotocin

Ethnopharmacological relevanceThe leaves of Syzygium cumini (L.) or Skeels (Myrtaceae) are widely used in Brazilian folk medicine to treat diabetes. Aim of the studyThe present study evaluated the functional capacity, biochemical parameters, oxidative stress and DNA damage from eight weeks of intervention with a crude hydroalcoholic extract of S. cumini leaves (EBH) and continuous aerobic training (TAC) in diabetic (D) rats. Materials and methodsA hydroalcoholic (50%) extract was prepared by ultrasound and phytochemical parameters (total phenols, total tannins and myricetin content) were analyzed. Thirty-seven male Wistar rats were divided into five groups: normoglycemic controls (CONT), diabetic controls (D-CONT), diabetics treated with extract (D+EBH), trained diabetic (D+TAC) and diabetics treated with extract and trained (D+EBH+TAC). Functional capacity was assessed with a maximum exercise capacity test; biochemical parameters with enzymatic kits; oxidative stress by superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS) and oxidized dichlorofluorescein (DCF), and the DNA damage by the comet assay. ResultsThe D+TAC and D+EBH+TAC groups showed better functional capacity at the end of interventions. The D+EBH group showed glucose and triglyceride reduction, lowest DNA damage index in the blood, liver, kidney, heart, lung and gastrocnemius muscle, improved SOD levels in the liver, kidney and lung, improved CAT levels in the kidney and lower lipid peroxidation in all tissues studied, compared to the D-CONT group. The exercise (D+TAC) was effective in reducing triglycerides, improving SOD levels in the lung, reducing lipid peroxidation in all tissues studied and reducing the DCF oxidation in the kidney, in addition to protecting against DNA damage in the blood and heart. However, the additive effect of the intervention protocols when combined (EBH+TAC) was observed only in improving the gastrocnemius SOD levels. The phytochemical analyses showed a high content of phenols and the presence of myricetin glycosides. ConclusionThe findings in this study suggest a crude hydroalcoholic extract of S. cumini leaves has potential hypoglycemic, hypolipidemic and protective properties acting against oxidative stress and against DNA damage, probably due to its phenols and myricetin glycoside content and the antioxidant properties of these constituents. Moreover, exercise was suggested to have beneficial effects on diabetes, improving functional capacity, ameliorating blood triglyceride control and decreasing lipid peroxidation, but with no effects on ameliorating blood glucose levels. The association of intervention protocols presented an additive effect on the antioxidant SOD activity in the muscle cells of diabetic rats.

The potential toxicological insights about the anti-HIV drug azidothymidine-derived monoselenides in human leukocytes: Toxicological insights of new selenium-azidothymidine analogs.

Acquired immunodeficiency syndrome (AIDS) is a worldwide disease characterized by impairments of immune function. AIDS can be associated with oxidative stress (OS) that can be linked to selenium (Se) deficiency. Se is fundamental for the synthesis of selenoproteins, such as glutathione peroxidase and thioredoxin reductase. These enzymes catalyze the decomposition of reactive oxygen species and contribute to maintain equilibrium in cell redox status. Literature data indicate that organoselenium compounds, such as ebselen and diphenyl diselenide, have antioxidant properties in vitro and in vivo models associated with OS. Nevertheless, selenocompounds can also react and oxidize thiols groups, inducing toxicity in mammals. Here, we tested the potential cytotoxic and genotoxic properties of six analogs of the prototypal anti-HIV drug azidothymidine (AZT) containing Se (5'-Se-(phenyl)zidovudine; 5'-Se-(1,3,5-trimethylphenyl)zidovudine; 5'-Se-(1-naphtyl)zidovudine; 5'-Se-(4-chlorophenyl)zidovudine) (C4); 5'-Se-(4-methylphenyl)zidovudine (C5); and 5'-(4-methylbenzoselenoate)zidovudine). C5 increased the rate of dithiothreitol oxidation (thiol oxidase activity) and C2-C4 and C6 (at 100 µM) increased DNA damage index (DI) in human leukocytes. Moreover, C5 (200 µM) decreased human leukocyte viability to about 50%. Taken together, these results indicated the low in vitro toxicity in human leukocytes of some Se-containing analogs of AZT.

Association of oxidative stress and DNA damage with grafting time in patients with multiple myeloma and lymphoma submitted to autologous hematopoietic stem cell transplantation.

The aim of the study was to investigate the association between oxidative stress and DNA damage with grafting time in patients submitted to autologous hematopoietic stem-cell transplantation (HSCT). The study included 37 patients submitted to autologous HSCT diagnosed with Multiple Myeloma (MM) and lymphoma (Hodgkin's and non-Hodgkin's). Biomarkers of oxidative stress and DNA damage index (DI) were performed at baseline (pre-CR) of the disease and during the conditioning regimen (CR), one day after the HSCT, ten days after HSCT and twenty days after HSCT, as well as in the control group consisting of 30 healthy individuals. The outcomes showed that both groups of patients had an hyperoxidative state with high DI when compared to baseline and to the control group and that the CR exacerbated this condition. However, after the follow-up period of the study, this picture was re-established to the baseline levels of each pathology. The study patients with MM showed a mean grafting time of 10.75 days (8 to 13 days), with 10.15 days (8 to 15 days) for the lymphoma patients. In patients with MM, there was a negative correlation between the grafting time and the basal levels of GPx (r = -0.54; p = 0.034), indicating that lower levels of this important enzyme are associated with a longer grafting time. For the DI, the correlation was a positive one (r = 0.529; p = 0.030). In the group with lymphoma, it was observed that the basal levels of NOx were positively correlated with grafting time (r = 0.4664, p = 0.032). The data indicate the potential of these biomarkers as predictors of toxicity and grafting time in patients with MM and Lymphomas submitted to autologous HSCT.

Evaluation of the Biochemical, Hematological and Genotoxic Parameters of Cebus Apella Treated with N-Methyl-Nitrosurea (NMU) Followed by Treatment with a Complex Homeopathic Compound (Canova)

Canova is a homeopathic compound that presents antimutagenic and anticancer properties . N-methyl-nitrosourea is a carcinogenic agent that causes alterations on DNA. This study was conducted to evaluate the antimutagenic effects of Canova on Cebus apella non-human primates treated with N-methyl-nitrosourea. Six animals were randomly assigned in two groups, one composed by two animals, who received only N-methyl-nitrosourea (NMU group) and another one consisting on four animals treated with N-methyl-nitrosourea followed by Canova treatment (CA group). Body weight, biochemical and hematological analysis were performed. Micronuclei test and Comet assay were carried out to evaluate genotoxicity. N-methyl-nitrosourea treatment led to an overall reduction in the hematologic cell count and the administration of Canova limited the adverse effects in the hematologic system on CA group. Canova also reduced micronuclei frequency and the DNA damage index. It suggests that Canova may have a role as an immune response modulator by inducing leukocyte proliferation.

Ductular reaction, cytokeratin 7 positivity, and gamma-glutamyl transferase in multistage hepatocarcinogenesis in rats.

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and is characterized by multistage formation. The presence of ductular reaction, cytokeratin 7 positivity (PCK7), and increased levels of gamma glutamyltransferase (γGT) has been observed during liver carcinogenesis and contribute to tumor progression. Our goal was to evaluate the ductular reaction in multistage carcinogenesis and to correlate PCK7 and γGT levels with tumor incidence, histological characteristics, liver DNA damage index, and the expression of oxidative stress proteins. HCC was induced in 24 male Wistar rats weighing 145-150g by chronic and intermittent exposure to 50 or 100mg/kg diethylnitrosamine (DEN). Six control animals received only vehicle. Blood was collected to determine hepatic enzyme levels. Animals were divided into three groups: control (CO), precancerous lesions (PL), and advanced HCC. Liver samples were obtained for immunohistochemical analyses and the measurement of protein expression. Statistical analyses included Tukey's test and Pearson's correlation analyses. We observed an extensive ductular reaction in advanced HCC and a strong correlation between PCK7 and levels of γGT and the poor prognosis and aggressiveness of HCC. The extent of PCK7 and high γGT levels were associated with overexpression of inducible nitric oxide synthase (iNOS) and heat shock factor protein 1 (HSF-1). However, PCK7 and γGT levels were negatively correlated with protein expression of nuclear factor erythroid 2-related factor 2 (NRF2) and inducible heat shock protein 70 (iHSP70). These findings suggest that ductular reaction is involved in the progression of multistage hepatocarcinogenesis.

High chromosomal instability in workers occupationally exposed to solvents and paint removers.

BackgroundPainters are exposed to an extensive variety of harmful substances like aromatic hydrocarbons used as solvents and paint removers, some of which have shown clastogenic activity. These substances constitute a complex mixture of chemicals which contain well-known genotoxicants, such as Benzene, Toluene and Xylene. Thus, chronic occupational exposure to such substances may be considered to possess genotoxic risk. In Colombia the information available around the genotoxic damage (Chromosomal and DNA damage) in car paint shop workers is limited and the knowledge of this damage could contribute not only to a better understanding of the carcinogenic effect of this kind of substances but also could be used as biomarkers of occupational exposure to genotoxic agents.ResultsIn this study, the genotoxic effect of aromatic hydrocarbons was assessed in peripheral blood lymphocytes of 24 workers occupationally exposed and 24 unexposed donors, by using Cytogenetic analysis and comet assay. A high frequency of Chromosomal alterations was found in the exposed group in comparison with those observed in the unexposed group. Among the total of CAs observed in the exposed group, fragilities were most frequently found (100 %), followed by chromosomal breaks (58 %), structural (41.2 %) and numerical chromosomal alterations (21 %). Numerical chromosomal alterations, fragilities and chromosomal breaks showed significant differences between exposed and unexposed groups. Among the fragilities, fra(9)(q12) was the most frequently observed. DNA damage index was also significantly higher in the exposed group compared to the unexposed group (p < 0.000).ConclusionsOur results revealed that occupational exposure to aromatic hydrocarbons is significantly associated with Chromosomal and DNA damage in car paint shops workers and are also indicative of high chromosomal instability. The high frequency of both Chromosomal Alterations and DNA Damage Index observed in this study indicates an urgent need of intervention not only to prevent the increased risk of developing cancer but also to the application of strict health control and motivation to the use of appropriate protecting devices during work.