DNA damage in leukocytes and serum nitrite concentration are negatively associated in type 1 diabetes.

Chronic hyperglycaemia leads to DNA damage in diabetes and might be associated with nitrosative stress. In this study, we aimed at assessing the level of DNA strand breaks in leukocytes, serum nitrite and nitrate in patients with type 1 diabetes and healthy controls and associations of these parameters with diabetes-related outcomes in a prospective study. The level of DNA damage was determined in 71 patients with type 1 diabetes and 57 healthy controls by comet assay and scored with arbitrary units (AU). The chemiluminescence method was used to measure nitrite and nitrate. Clinical information and data on consumption of alcohol, physical activity and smoking were collected. Progression of complications in patients with diabetes was assessed after a follow-up time of 4-5 years. We observed a higher level of DNA damage in leukocytes of patients with type 1 diabetes compared with healthy subjects [type 1 diabetes AU 50 (36-74.5); control AU 30 (24.1-43), P < 0.001]. According to regression, type 1 diabetes leads to a 2-fold increase in DNA damage. In the group of type 1 diabetes, DNA damage correlated positively with total cholesterol (R = 0.262, P = 0.028) and negatively with serum glucose level (R = -0.284; P = 0.018) and serum nitrite (R = -0.335; P = 0.008). DNA damage was not significantly associated with HbA1c, diabetes duration, complications and lifestyle factors. However, DNA damage > 57 AU was associated with statistically significantly lower serum nitrite and 1.52 higher risk of progression of complications of diabetes over the follow-up period. The latter result was not statistically significant due to insufficient study power [relative risk 1.52 (95% confidence interval = 0.68, 3.42, P = 0.31)]. Our results confirm that type 1 diabetes is associated with a higher level of DNA strand breaks in leukocytes when compared with the reference group and demonstrate the negative association between DNA damage and serum nitrite concentration.

Nitrosative stress parameters and the level of oxidized DNA bases in patients with multiple sclerosis.

Multiple sclerosis (MS) is a neurodegenerative disease with various factors affecting its etiology. Overproduction of nitric oxide and subsequent lesions of biopolymers are some of the possible causes of the disease. This study aimed to measure the most relevant nitrosative and oxidative stress biomarkers and the level of modified DNA bases in patients with MS. Each parameter was assayed in 25 patients with MS and 25 healthy controls. This study involved detecting blood plasma and serum nitric oxide metabolites by chemiluminescence detector Sievers NOA-280i, malondialdehyde (MDA) measurements with thiobarbituric acid reactive substance (TBARS) assay, detection of oxidized purines and pyrimidines with the enzyme-modified comet assay. Statistical analysis of the results was performed by one-way analysis of variance (ANOVA) and unpaired t test for the comparison of less than three data sets. DNA single-strand breaks, levels of modified purines and pyrimidines, as well as nitrite and nitrate levels in plasma and serum samples, were significantly higher in patients with MS than in healthy controls. On the contrary, MDA levels appeared to be lower in patients with MS.

Genotoxic and genoprotective effects of 1,4-dihydropyridine derivatives: a brief review.

This review summarises current knowledge about the genotoxic and genoprotective effects of 1,4-dihydropyridines (DHP) with the main focus on the water-soluble 1,4-DHPs. Most of these water-soluble compounds manifest very low calcium channel blocking activity, which is considered "unusual" for 1,4-DHPs. Glutapyrone, diludine, and AV-153 decrease spontaneous mutagenesis and frequency of mutations induced by chemical mutagens. AV-153, glutapyrone, and carbatones protect DNA against the damage produced by hydrogen peroxide, radiation, and peroxynitrite. The ability of these molecules to bind to the DNA may not be the only mechanism of DNA protection, as other mechanisms such as radical scavenging or binding to other genotoxic compounds may take place and enhance DNA repair. These uncertainties and reports of high 1,4-DHP concentrations damaging the DNA call for further in vitro and in vivo preclinical research, pharmacokinetic in particular, as it can help pinpoint the exact mechanism(s) of the genotoxic and/or genoprotective action of 1,4-DHPs.

Spectroscopic and electrochemical study of interactions between DNA and different salts of 1,4-dihydropyridine AV-153.

1,4-dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antimutagenic and DNA-binding activity. The latter activity was first described for water-soluble 1,4-DHP with carboxylic group in position 4, the sodium salt of the 1,4-DHP derivative AV-153 among others. Some data show the modification of physicochemical properties and biological activities of organic compounds by metal ions that form the salts. We demonstrated the different affinity to DNA and DNA-protecting capacity of AV-153 salts, depending on the salt-forming ion (Na, K, Li, Rb, Ca, Mg). This study aimed to use different approaches to collate data on the DNA-binding mode of AV-153-Na and five other AV-153 salts. All the AV-153 salts in this study quenched the ethidium bromide and DNA complex fluorescence, which points to an intercalation binding mode. For some of them, the intercalation binding was confirmed using cyclic voltammetry and circular dichroism spectroscopy. It was shown that in vitro all AV-153 salts can interact with four DNA bases. The FTIR spectroscopy data showed the interaction of AV-153 salts with both DNA bases and phosphate groups. A preference for base interaction was observed as the AV-153 salts interacted mostly with G and C bases. However, the highest differences were detected in the spectral region assigned to phosphate groups, which might indicate either conformational changes of DNA molecule (B form to A or H form) or partial denaturation of the molecule. According to the UV/VIS spectroscopy data, the salts also interact with the human telomere repeat, both in guanine quadruplex (G4) and single-stranded form; Na and K salts manifested higher affinity to G4, Li and Rb -to single-stranded DNA.

Blood levels of nitric oxide and DNA breaks assayed in whole blood and isolated peripheral blood mononucleated cells in patients with multiple sclerosis.

Oxidative stress, especially overproduction of nitric oxide (NO), is considered to be one of the crucial factors in the pathogenesis of multifactorial multiple sclerosis (MS). DNA breaks could be one of the consequences of oxidative stress; however, data on DNA breakage in MS are very few and contradictory. There are no data on direct measurements of NO production in the blood of MS patients. The goal of this study was to determine the level of single-stranded DNA breaks in whole blood or isolated peripheral blood mononuclear cells (PBMNCs) by means of alkaline single cell gel electrophoresis (comet assay) and to evaluate production of NO in the human blood by applying electron paramagnetic resonance (EPR) spectroscopy. Groups of healthy subjects and MS patients were enrolled in the study. Blood samples were obtained by vein puncture and divided in aliquots for the analysis of the whole blood and isolated PBMNC with comet assay. Alkaline single cell gel electrophoresis was performed on whole blood and isolated PBMNC samples of 28 patients and 15 controls. A separate blood sample was mixed with a spin-trap, frozen in liquid nitrogen and used for NO detection by EPR; 22 MS patients and 22 controls were tested. A statistically significant increase in the level of DNA breakage was observed in specimens taken from MS patients compared to healthy persons. The level of DNA damage in whole blood and PBMNCs of the same group was similar. NO production was significantly higher in the blood of MS patients.