Evaluation of low-to-moderate arsenic exposure, metabolism and skin lesions in a Turkish rural population exposed through drinking water.

BACKGROUND: There is no human data regarding the exposure, metabolism and potential health effects of arsenic (As) contamination in drinking water in the Central Anatolian region of Turkey. METHODS: Residents in ten villages with drinking water of total As (T-As) level >50 µg L-1 and 10-50 µg L-1 were selected as an exposed group (n = 420) and <10 µg L-1 as an unexposed group (n = 185). Time-weighted average-As (TWA-As) intake was calculated from T-As analysis of drinking water samples. Concentrations of T-As in urine and hair samples, urinary As species [i.e., As(III), As(V), MMA(V) and DMA(V], and some micronutrients in serum samples of residents of the study area were determined. Primary and secondary methylation indices (PMI and SMI, respectively) were assessed from urinary As species concentrations and the presence of skin lesion was examined. RESULTS: TWA-As intake was found as 75 µg L-1 in the exposed group. Urinary and hair T-As and urinary As species concentrations were significantly higher in the exposed group (P < 0.05). The PMI and SMI values revealed that methylation capacities of the residents were efficient and that there was no saturation in As metabolism. No significant increase was observed in the frequency of skin lesions (hyperpigmentation, hypopigmentation, keratosis) of the exposed group (P > 0.05). Only frequency of keratosis either at the hand or foot was higher in individuals with hair As concentration >1 µg g-1 (P < 0.05). CONCLUSIONS: Individuals living in the study area were chronically exposed to low-to-moderate As due to geological contamination in drinking water. No significant increase was observed in the frequency of skin lesions. Because of the controversy surrounding the health risks of low-to-moderate As exposure, it is critical to initiate long-term follow-up studies on health effects in this region.

A pooled analysis of molecular epidemiological studies on modulation of DNA repair by host factors.

Levels of DNA damage represent the dynamics between damage formation and removal. Therefore, to better interpret human biomonitoring studies with DNA damage endpoints, an individual's ability to recognize and properly remove DNA damage should be characterized. Relatively few studies have included DNA repair as a biomarker and therefore, assembling and analyzing a pooled database of studies with data on base excision repair (BER) was one of the goals of hCOMET (EU-COST CA15132). A group of approximately 1911 individuals, was gathered from 8 laboratories which run population studies with the comet-based in vitro DNA repair assay. BER incision activity data were normalized and subsequently correlated with various host factors. BER was found to be significantly higher in women. Although it is generally accepted that age is inversely related to DNA repair, no overall effect of age was found, but sex differences were most pronounced in the oldest quartile (>61 years). No effect of smoking or occupational exposures was found. A body mass index (BMI) above 25 kg/m2 was related to higher levels of BER. However, when BMI exceeded 35 kg/m2, repair incision activity was significantly lower. Finally, higher BER incision activity was related to lower levels of DNA damage detected by the comet assay in combination with formamidopyrimidine DNA glycosylase (Fpg), which is in line with the fact that oxidatively damaged DNA is repaired by BER. These data indicate that BER plays a role in modulating the steady-state level of DNA damage that is detected in molecular epidemiological studies and should therefore be considered as a parallel endpoint in future studies.

The hCOMET project: International database comparison of results with the comet assay in human biomonitoring. Baseline frequency of DNA damage and effect of main confounders.

The alkaline comet assay, or single cell gel electrophoresis, is one of the most popular methods for assessing DNA damage in human population. One of the open issues concerning this assay is the identification of those factors that can explain the large inter-individual and inter-laboratory variation. International collaborative initiatives such as the hCOMET project - a COST Action launched in 2016 - represent a valuable tool to meet this challenge. The aims of hCOMET were to establish reference values for the level of DNA damage in humans, to investigate the effect of host factors, lifestyle and exposure to genotoxic agents, and to compare different sources of assay variability. A database of 19,320 subjects was generated, pooling data from 105 studies run by 44 laboratories in 26 countries between 1999 and 2019. A mixed random effect log-linear model, in parallel with a classic meta-analysis, was applied to take into account the extensive heterogeneity of data, due to descriptor, specimen and protocol variability. As a result of this analysis interquartile intervals of DNA strand breaks (which includes alkali-labile sites) were reported for tail intensity, tail length, and tail moment (comet assay descriptors). A small variation by age was reported in some datasets, suggesting higher DNA damage in oldest age-classes, while no effect could be shown for sex or smoking habit, although the lack of data on heavy smokers has still to be considered. Finally, highly significant differences in DNA damage were found for most exposures investigated in specific studies. In conclusion, these data, which confirm that DNA damage measured by the comet assay is an excellent biomarker of exposure in several conditions, may contribute to improving the quality of study design and to the standardization of results of the comet assay in human populations.

Antioxidant effects of dexmedetomidine against hydrogen peroxide-induced DNA damage in vitro by alkaline Comet assay

Background/aim: Dexmedetomidine (DEX) is an alpha-2 adrenergic agonist that is commonly used as a sedative and anesthetic. The protective effects of DEX against oxidative damage under both in vitro and in vivo conditions have been demonstrated. It was aimed to evaluate and compare the protective effects of DEX and vitamin C (Vit C) on DNA against H2O2-induced DNA damage in human lymphocyte cell cultures in vitro by alkaline Comet assay. Materials and methods: Lymphocyte cell cultures were divided into 5 groups, as the negative control, solvent control, positive control, hydrogen peroxide (H2O2; 150 µM) + DEX (1 µM; 2.5 µM; 5 µM), and H2O2 (150 µM) + Vit C (1 µM; 2.5 µM; 5 µM), and incubated at 37 °C for 1 h. Cell viability was measured using the Trypan blue test. DNA damage was measured using the Alkali Comet Technique and the % percent tail intensity was evaluated. Statistical analysis was performed using 1-way ANOVA and the Tukey multiple comparison test. Results: It was observed that H2O2 significantly induced DNA damage in the lymphocytes and this damage was decreased significantly with Vit C and DEX. It was observed that Vit C at doses of 1 µM and 2.5 µM had a significantly stronger antioxidant effect, but there was no significant difference between the antioxidant effects of Vit C and DEX with a dose of 5 µM. The dose of 5 µM DEX was found to be the most effective in reducing oxidative DNA damage. Conclusion: There is limited data on the protective effects of DEX against oxidative DNA damage. The primary effect might be cytoprotection. The results herein showed that DEX was protective against H2O2-induced in vitro oxidative DNA damage in lymphocyte cell cultures in a dose-dependent manner. DEX might have a potential therapeutic value in the prevention of oxidative DNA damage in patients.

The association between the OPRM1 A118G polymorphism and addiction in a Turkish population.

Susceptibility to addiction has a complex genetic basis that includes genes associated with the action and metabolism of drugs of abuse. One important gene in that respect is OPRM1, which codes for the µ-opioid receptor and has an important role in mediating the rewarding effects of addiction substances. The aim of our study was to assess the prevalence of the OPRM1 A118G polymorphism (rs1799971) in Turkish population and to investigate its association with opioid and other substance addiction. In addition, we examined the association of rs1799971 in addicted patients who were also diagnosed with psychiatric disorders. The study included 103 patients addicted to opioids, cocaine, ecstasy, alcohol, lysergic acid diethylamide (LSD), cannabis, and sedative/hypnotic substances and 83 healthy volunteers with similar demographic features as controls. rs1799971 polymorphisms were identified with the polymerase chain reaction restriction fragment length polymorphism method (PCR-RFLP). The genotype frequencies were significantly higher in the addicted patients than controls (32.0 % vs 16.9 %, respectively; p=0.027). The prevalence of the G allele was 16.1 % in the addicted group and 8.4 % in the control group (p=0.031). Our study confirmed the association between the rs1799971(G) allele frequency and opioid and other substance addiction, but not with psychiatric disorders.

The role of DENND1A and CYP19A1 gene variants in individual susceptibility to obesity in Turkish population-a preliminary study.

Single nucleotide polymorphisms (SNPs), the most common genetic variations in human genome, can manage the predisposition of certain complex diseases or situations such as obesity. Genetic polymorphisms also play an important role as they can impact a population's susceptibility to being overweight or obese and developing related chronic complications such as hypertension, coronary heart disease, diabetes and cancer. The present study comprised of 193 unrelated healthy volunteers (120 females and 73 males) with Turkish origin. Only female adolescents (n = 110) were divided into 2 categories according to their BMI values as overweight (BMI ≥ 25) and normal (18.5 < BMI < 25) according to WHO classification. Genomic DNA was isolated from venous blood samples and genotyping of DENND1A rs10818854 and CYP19A1 rs2414096 variants was performed on Roche Light Cycler 2.0 Real-Time PCR platform. Serum hormone levels were analyzed by Electrochemiluminescent Immunoassay (ECLIA; Roche diagnostics). The genotype distributions were consistent with the Hardy-Weinberg equilibrium for both SNPs in the studied population (p > 0.05). The genotype distribution of DENND1A rs10818854 was determined for the first time in Turkish population and the variant allele frequency was found as 0.095. According to reduced sex hormone-binding globulin levels and increased free androgen index in the present study, obesity was linked with hyperandrogenism in female subjects. Both polymorphisms were investigated as potential genetic susceptibility markers for obesity and neither DENND1A nor CYP19A1 showed any associations.

Comparisons of the effects of the sevoflurane and propofol on acute ischemia reperfusion and DNA damages in rabbits / Comparações dos efeitos de sevoflurano e propofol sobre isquemia-reperfusão aguda e danos ao DNA em coelhos

Abstract Background and objectives: The aim of this study was to compare the effects of sevoflurane and propofol anesthesia on oxidative DNA damage that occurs in low-extremity ischemia and is caused by tourniquet application. Methods: Fourteen New Zealand rabbits were randomly allocated into two equal groups. Group S (n = 7) received sevoflurane (2.5-4 percent) inhalation and Group P (n = 7) received a propofol infusion (1-2 mg·kg-1·min-1), after which a pneumatic tourniquet was placed on the right lower extremity. Blood samples were collected prior to tourniquet placement (baseline), 120 min after ischemia, 15 min after ischemia and 120 minutes (min) after ischemia. Malondialdehyde (MDA) levels were analyzed to determine lipid peroxidation, and single cell gel electrophoresis (SCGE) was used to determine DNA damage. Results: At 15 min after ischemia, the MDA levels in Group P (8.15 ± 2.61 µM) were higher than baseline (6.26 ± 3.19 µM, p = 0.026) and Group S (4.98 ± 0.77 µM, p = 0.01). DNA damage was similar in both groups, although DNA damage was higher than baseline (tail moment 0.63 ± 0.27, tail intensity 3.76 ± 1.26) in Group P at the 15th minute of reperfusion (tail moment 1.05 ± 0.45, p = 0.06; tail intensity 5.33 ± 1.56, p = 0.01). The increase in tail moment and tail intensity returned to normal levels in both groups 2 hours after the termination of ischemia. Conclusion: Given that oxidative stress and genotoxic effect disappear in the late stages of reperfusion, we conclude that neither sevoflurane nor propofol can be considered superior to the other in anesthesia practices for extremity surgeries involving the use of a tourniquet.

Resumo Justificativa e objetivos: Comparar os efeitos da anestesia com sevoflurano e propofol sobre o dano oxidativo ao DNA que ocorre na isquemia de extremidade inferior e é causada pela aplicação de torniquete. Métodos: Foram alocados aleatoriamente em dois grupos iguais 14 coelhos da raça Nova Zelândia. Grupo S (n = 7) recebeu inalação de sevoflurano (2,5-4%) e Grupo P (n = 7) recebeu perfusão de propofol (1-2 mg·kg-1·min-1), logo após um torniquete pneumático foi colocado na extremidade inferior direita. Amostras de sangue foram coletadas antes da colocação do torniquete (fase basal), após 120 minutos de isquemia, 15 minutos após a isquemia e 120 minutos após a isquemia. Os níveis de malondialdeído (MDA) foram analisados para determinar a peroxidação de lipídios e eletroforese em gel de célula única (EGCU) foi usada para determinar o dano ao DNA. Resultados: Aos 15 minutos após a isquemia, os níveis de MDA no Grupo P (8,15 ± 2,61 µM) foram superiores aos da fase basal (6,26 ± 3,19 µM, p = 0,026) e dp Grupo S (4,98 ± 0,77 µM, p = 0,01). O dano causado ao DNA foi semelhante nos dois grupos, embora tenha sido maior do que na fase basal (momento da cauda 0,63 ± 0,27, intensidade da cauda 3,76 ± 1,26) no Grupo P no 15 minutos de reperfusão (momento da cauda 1,05 ± 0,45, p = 0,06; intensidade da cauda 5,33 ± 1,56, p = 0,01). O aumento no momento da cauda e a intensidade da cauda voltaram aos níveis normais nos dois grupos duas horas após o término da isquemia. Conclusão: Como o estresse oxidativo e o efeito genotóxico desaparecem nos estágios finais da reperfusão, concluímos que não há superioridade tanto de sevoflurano quanto de propofol em práticas de anestesia para procedimentos cirúrgicos de extremidades que envolvem o uso de torniquete.

[Comparisons of the effects of the sevoflurane and propofol on acute ischemia reperfusion and DNA damages in rabbits]. / Comparações dos efeitos de sevoflurano e propofol sobre isquemia­reperfusão aguda e danos ao DNA em coelhos.

BACKGROUND AND OBJECTIVES: The aim of this study was to compare the effects of sevoflurane and propofol anesthesia on oxidative DNA damage that occurs in low-extremity ischemia and is caused by tourniquet application. METHODS: Fourteen New Zealand rabbits were randomly allocated into two equal groups. Group S (n=7) received sevoflurane (2.5-4 percent) inhalation and Group P (n=7) received a propofol infusion (1-2mg·kg-1·min-1), after which a pneumatic tourniquet was placed on the right lower extremity. Blood samples were collected prior to tourniquet placement (baseline), 120min after ischemia, 15min after ischemia and 120minutes (min) after ischemia. Malondialdehyde (MDA) levels were analyzed to determine lipid peroxidation, and single cell gel electrophoresis (SCGE) was used to determine DNA damage. RESULTS: At 15min after ischemia, the MDA levels in Group P (8.15±2.61µM) were higher than baseline (6.26±3.19µM, p=0.026) and Group S (4.98±0.77µM, p=0.01). DNA damage was similar in both groups, although DNA damage was higher than baseline (tail moment 0.63±0.27, tail intensity 3.76±1.26) in Group P at the 15th minute of reperfusion (tail moment 1.05±0.45, p=0.06; tail intensity 5.33±1.56, p=0.01). The increase in tail moment and tail intensity returned to normal levels in both groups 2hours after the termination of ischemia. CONCLUSION: Given that oxidative stress and genotoxic effect disappear in the late stages of reperfusion, we conclude that neither sevoflurane nor propofol can be considered superior to the other in anesthesia practices for extremity surgeries involving the use of a tourniquet.

Comparisons of the effects of the sevoflurane and propofol on acute ischemia reperfusion and DNA damages in rabbits.

BACKGROUND AND OBJECTIVES: The aim of this study was to compare the effects of sevoflurane and propofol anesthesia on oxidative DNA damage that occurs in low-extremity ischemia and is caused by tourniquet application. METHODS: Fourteen New Zealand rabbits were randomly allocated into two equal groups. Group S (n=7) received sevoflurane (2.5-4 percent) inhalation and Group P (n=7) received a propofol infusion (1-2mg·kg-1·min-1), after which a pneumatic tourniquet was placed on the right lower extremity. Blood samples were collected prior to tourniquet placement (baseline), 120min after ischemia, 15min after ischemia and 120minutes (min) after ischemia. Malondialdehyde (MDA) levels were analyzed to determine lipid peroxidation, and single cell gel electrophoresis (SCGE) was used to determine DNA damage. RESULTS: At 15min after ischemia, the MDA levels in Group P (8.15±2.61µM) were higher than baseline (6.26±3.19µM, p=0.026) and Group S (4.98±0.77µM, p=0.01). DNA damage was similar in both groups, although DNA damage was higher than baseline (tail moment 0.63±0.27, tail intensity 3.76±1.26) in Group P at the 15th minute of reperfusion (tail moment 1.05±0.45, p=0.06; tail intensity 5.33±1.56, p=0.01). The increase in tail moment and tail intensity returned to normal levels in both groups 2hours after the termination of ischemia. CONCLUSION: Given that oxidative stress and genotoxic effect disappear in the late stages of reperfusion, we conclude that neither sevoflurane nor propofol can be considered superior to the other in anesthesia practices for extremity surgeries involving the use of a tourniquet.

The role of oxidative DNA damage and GSTM1, GSTT1, and hOGG1 gene polymorphisms in coronary artery disease risk.

OBJECTIVE: Atherosclerotic coronary artery disease (CAD) appears to be a multifactorial process caused by the interaction of environmental risk factors with multiple predisposing genes. Therefore, in this study we aimed to determine the role of oxidative DNA damage and some variations in glutathione S-transferase (GSTM1 and GSTT1) and DNA repair (hOGG1) genes in CAD risk. METHODS: A case-control study was conducted on 59 individuals who had undergone coronary angiographic evaluation. Of these, 29 were patients diagnosed with CAD (mean age =61.5±10.3) and 30 were controls examined for reasons other than suspected CAD and who had angiographically documented normal coronary arteries (mean age =60.4±11.6). Basal DNA damage as well as pyrimidine and purine base damage were evaluated in peripheral blood lymphocytes using the modified comet assay. Polymerase chain reaction-restriction length polymorphism (PCR-RFLP)-based assay was used for genotyping. RESULTS: Basal DNA damage levels in patients [9.16 (3.26)] were significantly higher than those in controls [7.59 (3.23); p=0.017], and basal DNA and pyrimidine base damage levels were significantly correlated with disease severity based on Gensini scoring (r=0.352, p=0.006; r=0.318, p=0.014, respectively). However, no significant differences were observed in terms of oxidized DNA bases between patients and controls. The frequencies of studied genotypes (GSTM1, GSTT1, and hOGG1) were similar between groups. CONCLUSION: The results of this study pointed out the role of DNA damage in CAD and its severity. However, GSTM1, GSTT1, and hOGG1 gene polymorphisms seemed to have no effect on individual susceptibility for disease progression.

Micronucleus assay assessment of possible genotoxic effects in patients treated with titanium alloy endosseous implants or miniplates.

The use of titanium and its alloys (Ti-6Al-4V) for oral surgery has increased dramatically in recent years. Ti is a stable biocompatible metal suitable for oral applications and it has been used for endosseous subperiosteal implants and miniplate fixation for more than 25 years. Dental implants are typically made of Ti or Ti alloys. The alloys are potentially toxic due to release of vanadium and aluminum. We tested the possible genotoxicity of Ti alloy endosseous implants and miniplates on the oral mucosal tissues of two groups of patients: 17 patients receiving Ti miniplate and screw fixation, and 37 endosseous dental implant placement patients. Preoperative and postoperative mucogingival cell samples were collected. Genotoxicity was assessed by the micronucleus assay (MN). There were slight but not statistically significant increases in the frequencies of MN (p=0.087 and p=0.047) post-operation in both groups. In summary, neither of the applications showed genotoxicity in the oral epithelial cells of patients.

In vivo genotoxicity assessment of sertraline by using alkaline comet assay and the cytokinesis-block micronucleus assay.

Sertraline, a leading antidepressant in the selective serotonin reuptake inhibitor (SSRI) group of medicine, is the most frequently prescribed drug. In this study, the alkaline comet assay and the cytokinesis-block micronucleus (CBMN) assay were used to investigate genotoxicity potential of sertraline in the peripheral blood lymphocytes (PBLs) of acute and chronic sertraline-treated Wistar albino rats. Male Wistar albino rats (n = 48) were administered low, medium and high doses of sertraline (10, 40, 80 mg/kg) for acute and chronic treatment by employing the gavage method to investigate genotoxicity of the administered drug. The data (tail length, tail intensity and tail moment) were analysed and indicated that there was no statistically significant difference between sertraline-treated groups and the negative control group with respect to DNA damage (p > 0.05). However, it was observed that acute sertraline administration had caused much more DNA damage in comparison with chronic treatment (p < 0.05). According to the data obtained from the CBMN test, an increase in the micronucleus (MN) frequency was detected at chronic and high-dose acute sertraline treatment. Based on the outcome of comet assay, detection of statistically insignificant DNA damage may be due to the fact that sertraline did not cause damage on DNA. Also, increase in frequency of MN in chronic sertraline treatment suggests that chronic sertraline administration might influence some mechanisms of cell division. Therefore, dose adjustment in depressed patients seems significant as it may help prevent further prognosis of the diseases.

Assessment of individual susceptibility to baseline DNA and cytogenetic damage in a healthy Turkish population: evaluation with lifestyle factors.

BACKGROUND: Cytogenetic biomarkers are most frequently used well-established endpoints in human population studies with their sensitivity for measuring exposure to genotoxic agents. They have an important role as early predictors of cancer risk. Identification of individual genotypes of metabolic gene polymorphisms helps to understand the modulation of cancer susceptibility by environmental exposures, such as cigarette smoking and other lifestyle factors. AIM: To evaluate individual susceptibility to chemicals, we determined individual DNA damage related to glutathione S-transferase (GST) genotypes (GSTM1, GSTT1, and GSTP1) in a Turkish population. METHODS: Peripheral blood lymphocytes (PBL) and DNA samples of 127 subjects were analyzed for the presence of DNA damage, using single-cell gel electrophoresis (the Comet assay), and for cytogenetic parameters (chromosomal aberrations [CAs], bleomycin-induced CA, and a cytokinesis-blocked micronucleus assay), and the polymerase chain reaction/restriction fragment length polymorphism method, respectively. RESULTS: Individuals carrying a GSTT1-null allele showed higher frequencies of CA and micronucleus (MN) (p=0.026, p=0.003, respectively), whereas the GSTM1-null and GSTP1 mutant genotypes did not show any differences in cytogenetic parameters. Our findings demonstrated that none of the lifestyle factors (smoking, alcohol drinking, dietary habits, vitamin intake, and physical activity), except for vitamin intake (p=0.002), were significantly associated with the studied cytogenetic parameters. CONCLUSION: Our results suggest that the GSTT1 gene polymorphism may influence the baseline cytogenetic frequency in a healthy population.

The role of GSTM1, GSTT1, GSTP1, and OGG1 polymorphisms in type 2 diabetes mellitus risk: a case-control study in a Turkish population.

The aim of the present study was to investigate the role of some polymorphisms in GSTs (GSTM1, GSTT1 and GSTP1) which are very important protective mechanisms against oxidative stress and in OGG1 gene which is important in DNA repair, against the risk of type 2 diabetes mellitus (T2DM). 127 T2DM and 127 control subjects were included in the study. DNA was extracted from whole blood. Analyses of GSTM1 and GSTT1 gene polymorphisms were performed by allele specific PCR and those of GSTP1 Ile105Val and OGG1 Ser326Cys by PCR-RFLP. Our data showed that GSTM1 null genotype frequency had a 2-6 times statistically significant increase in a patient group (OR=3.841, 95% CI=2.280-6.469, p<0.001) but no significance with GSTT1 null/positive and GSTP1 Ile105Val genotypes was observed. When T2DM patients with OGG1 Ser326Cys polymorphism were compared with patients with a wild genotype, a 2-3 times statistically significant increase has been observed (OR 1.858, 95% CI=1.099-3.141, p=0.021). The combined effect of GSTM1 null and OGG1 variant genotype frequencies has shown to be statistically significant. Similarly, the risk of T2DM was statistically increased with GSTM1 null (OR=3.841, 95% CI=2.28-6.469), GSTT1 null+GSTP1 (H+M) (OR=4.118, 95% CI=1.327-12.778) and GSTM1 null+OGG1 (H+M) (OR=3.322, 95% CI=1.898-5.816) and GSTT1 null+OGG1 (H+M) (OR=2.179, 95% CI=1.083-4.386) as compared to the control group. According to our study results, it has been observed that the combined evaluation of GSTM1-GSTT1-GSTP1 and OGG1 Ser326Cys gene polymorphisms can be used as candidate genes in the etiology of T2DM, especially in the development of T2DM.

DNA damage, glutathione, and total antioxidant capacity in anesthesia nurses.

The possibilities of a potential mutagenic/carcinogenic action of waste anesthetic gases in occupationally exposed anesthesia personnel have been previously reported in several studies. The aim of this study was to assess the DNA damage, reduced glutathione (GSH), and total antioxidant capacity (TAC) in anesthesia nurses. DNA damage was determined with comet assay, GSH levels were measured spectrophotometrically, and TAC was determined by using Randox kit. Anesthesia nurses (n = 40) showed increased DNA damage in terms of mean percentage of the total DNA in the comet tail compared to controls (n = 40) (p < .001). Mean TAC and GSH levels of the anesthesia nurses were significantly lower than that of the controls (p < .001, p < .05, respectively). The results of this study indicate that occupational exposure to anesthetic gases induce DNA damage, which may lead to changes in TAC and GSH levels.

The role of oxidative DNA damage, DNA repair, GSTM1, SOD2 and OGG1 polymorphisms in individual susceptibility to Barrett's esophagus.

Determination of the genetic alterations, which play a role in the etiology of Barrett's esophagus (BE), could help identify high-risk individuals for esophageal adenocarcinoma (EA). The aim of the present study was to investigate the role of oxidative DNA damage, glutathione (GSH) concentration as oxidative stress parameters and DNA repair capacity, GSTM1, SOD1 Ala16Val and OGG1 Ser326Cys genetic polymorphisms as individual susceptibility parameters in the etiology of BE. The study groups comprised BE patients who were clinically diagnosed (n = 40) and a healthy control group (n = 40). Basal DNA damage, pyrimidine and purine base damage after H(2)O(2) induction, H( 2)O(2) sensitivity, DNA repair capacity, oxidized pyrimidine and purine base damage repair were evaluated in peripheral blood lymphocytes with a modified comet assay using specific endonucleases (Endo III and Fpg). Polymerase chain reaction-restriction length polymorphism (PCR-RFLP)-based assays were used for genotyping. The patient group showed elevated levels of basal DNA damage, pyrimidine base damage and H(2)O(2) sensitivity as compared to controls (p < .05). DNA repair capacity, oxidized pyrimidine and purine base damage repair capacity, were not statistically different between patients and controls. GSH concentration was found to be significantly lower in smoking patients than in the controls (p < .05). None of the genetic variations changed the risk of having BE disease. However, patients carrying the variant OGG1 Cys allele showed elevated levels of pyrimidine base damage as compared to patients carrying the wild-type OGG1 Ser (p < .05). The results of this study point to a role of oxidative DNA damage in BE. However, DNA repair capacity, GSTM1, SOD1 Ala16Val and OGG1 Ser326Cys genetic polymorphisms appeared to play no role in the individual susceptibility to this disease.

Assessment of DNA damage in postmenopausal women under osteoporosis therapy.

OBJECTIVE: The following study was designed to examine possible DNA damage levels in peripheral blood leukocytes, using the alkaline Comet assay, isolated from postmenopausal women undergoing osteoporosis treatment. STUDY DESIGN: Thirty-two postmenopausal women were randomized into two groups of 16. A dosage of 2.5 mg/day of tibolone (Livial) and 10mg/day of alendronate sodium (Fosamax) were administered to Group 1 over a 12-month period while Group 2 took 10 mg/day of alendronate alone over the same period. The control group consisted of 16 postmenopausal women who did not receive any treatment. Genotoxicity was assessed by the standard method of alkaline Comet assay. RESULTS: When the results of the study groups were compared with those of the control group, significant differences in terms of DNA damage levels were found (p<0.05). However, no difference was detected between Groups 1 and 2 (p>0.05). CONCLUSION: Although, no statistical difference in terms of DNA damage levels between tibolone plus alendronate as opposed to alendronate alone was found, an increase in DNA damage levels was observed in Groups 1 and 2 compared with the control group. Consequently, it can be asserted that the frequency of DNA damage in postmenopausal women with osteoporosis increases under alendronate treatment with or without tibolone.

Genoprotective role of vitamin E and selenium in rabbits anaesthetized with sevoflurane.

In this study, genotoxic effects of repeated sevoflurane anaesthesia were investigated in rabbits with or without antioxidant supplementation. Twenty-one New Zealand male rabbits were included in the study and randomized into three groups as: placebo treated (Group I), vitamin E supplemented (Group II) and selenium supplemented (Group III). Vitamin E and selenium were given intraperitoneally for 15 days before anaesthesia treatment. Anaesthesia was administered using 3% sevoflurane in 4 L/min oxygen for a 3-hour period and continued for 3 days. Blood samples were collected before anaesthesia (Sample 1), after the first, second and third days of sevoflurane administration (Sample 2, Sample 3 and Sample 4 respectively) and the last samples were taken 5 days after the last sevoflurane administration (Sample 5). Genotoxic damage was examined using the comet assay. The degree of damage is assessed by grading the cells into three categories of no migration (NM), low migration (LM) and high migration (HM) depending on the fraction of DNA pulled out into the tail under the influence of the electric field. The number of comets in each sample was calculated (1 x number of comets in category NM+2 x number of comets in category LM+3 x number of comets in category HM) and expressed as the total comet score (TCS), which summarizes the damage frequencies. In Group I, a significant increase in the mean TCSs was observed for Samples 3 and 4 as compared with Sample 1. However, there were no significant differences between Samples 1, 2 and 5. The mean TCS of Sample 4 was significantly higher than Sample 1, 2 and 3 in Group II. Group III demonstrated no significant mean TCSs for any experimental conditions. Statistical differences were also observed between the groups with significant P values. This experimental study points out the presence of DNA damage with repeated sevoflurane anaesthesia and the genoprotective role of antioxidant supplementation on DNA damage in mononuclear leukocytes of rabbits by highly sensitive comet assay.

Detection of oxidative DNA damage in lymphocytes of patients with Alzheimer's disease.

Oxidative damage to DNA may play an important role in both normal ageing and in neurodegenerative diseases. The deleterious consequences of excessive oxidations and the pathophysiological role of reactive oxygen species have been intensively studied in Alzheimer's disease. Although the role of oxidative stress in the aetiology of Alzheimer's disease is still not clear, the detection of an increased damage status in the cells of patients could have important therapeutic implications. The levels of oxidative damage in peripheral lymphocytes of 24 Alzheimer's disease patients and of 21 age-matched controls were determined by comet assay applied to freshly isolated blood samples with oxidative lesion-specific DNA repair endonucleases (endonuclease III for oxidized pyrimidines, formamidopyrimidine glycosylase for oxidized purines). It was demonstrated that Alzheimer's disease is associated with elevated levels of oxidized pyrimidines and purines (p<0.0001) as compared with age-matched control subjects. It was also demonstrated that the comet assay is useful as a biomarker of oxidative DNA damage when used with oxidative lesion-specific enzymes.