DNA integrity in patients undergoing hyperbaric oxygen (HBO) therapy.

Hyperbaric oxygen (HBO) therapy is successfully applied for a wide variety of diseases. However, recent studies in humans undergoing (HBO) therapy have revealed that HBO is able to induce oxidative DNA damage especially in lymphocytes while the biological significance of this outcome is still not clear. HBO mediated DNA damage in lymphocytes has been determined by using the alkaline version of the comet assay in order to detect DNA strand breakages in patients undergoing HBO therapy. Blood samples were obtained from 100 voluntary patients and were drawn by venipuncture before and immediately after the first session of HBO treatment. The DNA damaging effect of HBO has also been evaluated in the fifth session of HBO therapy. DNA strand breakages were significantly increased after the first session of HBO treatment. However the elevated DNA strand breaks returned to their normal levels in lymphocytes after two hours of in vitro incubation. The elevated DNA strand breaks consistently decreased and reached to the baseline levels after the fifth session of HBO therapy. The results of this study, conducted in patients undergoing HBO therapy, support the existence of the previously reported cellular adaptive response against HBO mediated oxidative DNA damage in experimental studies.

The relationship of PON1 QR 192 and LM 55 polymorphisms with serum paraoxonase activities of Turkish diabetic patients.

Paraoxonase (PON1) is a serum esterase responsible for the protection against xenobiotics toxicity such as paraoxon. Alterations in PON1 concentrations have been reported in a variety of diseases including diabetes mellitus (DM). It has been shown that the serum PON1 concentration and activity are decreased in patients with both type 1 and type 2 DM. This study aimed to investigate the lipid profiles and the relationship between PON1 activity and PON1, QR192 and LM55 polymorphisms in Turkish type 2 diabetic patients and non-diabetic control subjects. According to our results, RR variant had significantly higher PON activity than QQ and QR variants (p < 0.01) and LL variant had significantly higher PON activity than MM variant in both control and patient groups (p < 0.05). In conclusion, we found that PON1 192RR and 55LL genotypes are associated with higher PON activity than QQ and MM genotypes. This may be more protective to lipid peroxidation.

Are PON1 Q/R 192 and M/L 55 polymorphisms risk factors for diabetes complications in Turkish population?

OBJECTIVES: We investigated whether the human serum paraoxonase (PON1) Q/R 192 and M/L 55 polymorphisms are associated with the complications of the type 2 diabetes (T2D). DESIGN AND METHODS: Study group was consisted of 50 healthy subjects and 100 type 2 diabetes mellitus (DM) patients. Following measuring of serum PON1 activity, isolation of DNA and genotyping analyses were performed. RESULTS: PON1 activity of the patients with complications was significantly reduced by 23.5% compared to the group of diabetic patients and by 26.3% than the controls. According to multivariate analysis, we observed a three times significant effect of Q/R 192 polymorphism on the susceptibility to the occurrence of complications. CONCLUSIONS: Protective effects of paraoxonase against peroxidation of LDL particles are important in T2D complications. Although both of the two polymorphisms are associated, 192 polymorphism seems to be stronger predictor of the risk of diabetic complications.

Possible effect of gene polymorphisms on the release of TNFα and IL1 cytokines in coal workers' pneumoconiosis.

It has been shown that coal dust exposure stimulates inflammatory response leading to increased release of cytokines from monocytes such as TNF-alpha and IL1. These released cytokines play the key role in the pathogenesis of pneumoconiosis including coal workers' pneumoconiosis. In this study, we investigated TNFA, IL1A, IL1B and IL1RA genes variations on basal, lipopolysaccharide and coal dust-induced cytokine release from blood monocytes of homozygous allele and minor variant allele carriers in Turkish coal workers and CWP patients. According to the genotyping results, TNFA -238 gene polymorphism was found as a risk factor in CWP development (OR=3.79) and to in vitro results; release of both TNF-alpha and IL1 cytokines from the monocytes in CWP patients was significantly increased compared to the healthy workers. Also, LPS and coal dust stimulated release of TNF-alpha, which was significantly higher in allele 2 carriers compared to subjects carrying allele 1 in both the groups. These data suggest that the coal dust-induced release of TNF-alpha from monocytes may be a useful biomarker of CWP.

Deoxycholic acid at neutral and acid pH, is genotoxic to oesophageal cells through the induction of ROS: The potential role of anti-oxidants in Barrett's oesophagus.

Bile acids are often refluxed into the lower oesophagus and are candidate carcinogens in the development of oesophageal adenocarcinoma. We show here that the secondary bile acid, deoxycholic acid (DCA), is the only one of the commonly refluxed bile acids tested here, to show genotoxicity, in terms of chromosome damage and mutation induction in the human p53 gene. This genotoxicity was apparent at both neutral and acidic pH, whilst there was a considerable increase in bile-induced toxicity at acidic pH. The higher levels of cell death and low cell survival rates at acidic pH may imply that acid bile exposure is toxic rather than carcinogenic, as dead cells do not seed cancer development. We also show that DCA (at neutral and acid pH) induced the release of reactive oxygen species (ROS) within the cytoplasm of exposed cells. We further demonstrate that the genotoxicity of DCA is ROS mediated, as micronucleus induction was significantly reduced when cells were treated with DCA + the anti-oxidant vitamin C. In conclusion, we show that DCA, is an effective genotoxin at both neutral and acidic pH. As bile acids like DCA can induce DNA damage at neutral pH, suppressing the acidity of the refluxate will not completely remove its carcinogenic potential. The genotoxicity of DCA is however, ROS dependent, hence anti-oxidant supplementation, in addition to acid suppression may block DCA driven carcinogenesis in Barrett's patients.

Cytochrome P450 (CYP) and glutathione S-transferases (GST) polymorphisms (CYP1A1, CYP1B1, GSTM1, GSTP1 and GSTT1) and urinary levels of 1-hydroxypyrene in Turkish coke oven workers

Genetic polymorphisms of xenobiotic metabolizing enzymes have been associated with cancer risk. We evaluated the influences of genetic polymorphisms of polycyclic aromatic hydrocarbon (PAH) metabolizing enzymes on urinary 1-hydroxypyrene (1-OHP) excretion in Turkish coke oven workers. Urinary 1-OHP was analyzed by HPLC after enzymatic hydrolysis. Lymphocyte DNA was used for PCR-based genotyping of cytochrome P450 (CYP) polymorphisms (CYP1A1 and CYP1B1) and glutathione S-transferases (GST) polymorphisms (GSTM1, GSTT1 and GSTP1). The mean urinary 1-OHP levels of coke oven workers were significantly higher than that of controls. No significant difference was detected in the mean urinary 1-OHP levels of smokers and non-smokers either for coke oven workers or controls. Genetic polymorphisms of the CYPs and GSTs studied had no significant influence on 1-OHP excretion in coke oven workers, but in the control group the urinary 1-OHP levels of individuals carrying the GSTT1- genotype were significantly higher than those of individuals carrying GSTT1+ genotype. The duration of occupational exposure and metabolic genotype for GSTT1 were the significant predictors of urinary 1-OHP levels. The control individuals carrying combined GSTM1-/GSTT1- genotypes also had significantly higher levels of urinary 1-OHP than those of individuals carrying GSTM1+/GSTTI+, GSTM1-/GSTT1+, and GSTM1+/GSTT1- genotypes. These results indicate that urinary 1-OHP is a sensitive indicator of recent human exposure to PAHs and that genetic polymorphism of GSTT1 may also to some extent reflect the interindividual variation in susceptibility to PAHs only at low PAH exposure.

Polymorphisms of cytochrome P450 1A1, glutathione S-transferases M1 and T1 in a Turkish population.

Intra-ethnic as well as inter-ethnic differences are known to exist in the frequencies of cytochrome P450 (CYP) 1A1, glutathione S-transferase (GST) M1, and GSTT1 gene polymorphisms with which associations have been shown for several cancers. In this study, CYP1A1 m2, GSTM1, and GSTT1 gene polymorphisms were determined among 133 healthy individuals of a Turkish population. On the basis of polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) methodology, the frequency of CYP1A1 m2 mutation was determined. The multiplex PCR protocol was used to determine the frequency of the deleted genotypes of both GSTM1 and GSTT1 genes. The frequencies of Ile/Ile (wild type), Ile/Val (heterozygous variant), and Val/Val (homozygous variant) CYP1A1 m2 genotypes were 90.2%, 9.8%, and 0%, respectively. The frequencies of the deleted GSTM1 (null) and GSTT1 (null) genotypes were 51.9% and 17.3%, respectively. These results show that the frequencies of the CYP1A1 m2, GSTM1, and GSTT1 gene polymorphisms in a Turkish population are similar to Caucasian populations.