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A comparative analysis of three single nucleotide variations of the proteasomal genes PSMA3 (rs2348071) and PSMA6 (rs2277460 and rs1048990) was carried out in the groups of children from 1 to 16 years old with the autoimmune rheumatic disease - juvenile idiopathic arthritis (JIA; n = 199), with articular syndrome of non-autoimmune etiology (n = 229) and in the clinical control group with neither autoimmune nor chronic inflammatory diseases (n = 379). PCR, PCR–RFLP and real-time PCR were used for genotyping. It was found that the CG genotype and G allele of rs10489990 polymorphism (OR = = 1.93; 95 % CI 1.29-2.90; p = 0.002 and OR = 1.51; 95 % CI 1.11-2.04; p = 0.008 respectively), as well as the AA genotype of rs2348071 polymorphism (OR = 1.89; 95 % CI 1.02–3.49; p = 0.044) are associated with the JIA susceptibility, but not with articular syndrome. The established JIA risk genotypes may indicate the involvement of PSMA3 and PSMA6 genes in the development of an autoimmune reaction. In combination with other risk DNA markers, they can be proposed to assess a genetic predisposition to JIA. It was also revealed that the frequencies of risk genotypes and alleles for JIA in the group of patients with articular syndrome as a whole occupy an intermediate position between JIA and control group frequencies. This may indicate an increased JIA risk in some patients with articular syndrome.

Background Genetic variations of neutrophil cytosolic factor 2 (NCF2), a subunit of NADPH oxidase, are usually associated with chronic granulomatous disease, and their relationship with autoimmune disorders through the defective NADPH oxidase function during phagocytosis is suggested. Our study aimed to explore whether there is an association between the non‐synonymous single nucleotide polymorphism in the NCF2 gene (rs17849502, NC_000001.11:g.183563445G>T) and the development of juvenile autoimmune rheumatic diseases. Methods In order to test this hypothesis, we conducted a pilot case–control study. In total, 709 children and adolescents, all Belarusians, were involved in the study including patients with juvenile‐onset systemic lupus erythematosus (JSLE), juvenile idiopathic arthritis (JIA), Kawasaki disease (KD), and subjects without autoimmune and inflammatory diseases as the clinical control, as well as health newborns as the population control. Real‐time polymerase chain reaction was used for genotyping. Results The minor T allele of NCF2 occurred most frequently in patients with JSLE (OR = 2.60, 95% CI = 1.18–5.73, p = 0.023 as compared to the clinical control). In groups with JIA and KD, its frequency did not differ from the control. The TT genotype was only observed in 5.7% of patients with JSLE (p = 0.007), but not in other groups. Conclusion Therefore, our study suggested that NCF2 rs17849502 polymorphism is a potential genetic risk factor for JSLE, while it is probably not for such autoimmune rheumatic diseases as JIA or KD., As far as we know, our study is the first one that identifies the rs17849502 functional polymorphism of the NCF2 gene may be a genetic risk factor of juvenile‐onset systemic lupus erythematosus (JSLE) in the European population. The results of our pilot work also suggest that it is probably not for other autoimmune rheumatic diseases, such as juvenile idiopathic arthritis or Kawasaki disease. These data highlight the importance of NCF2 polymorphism in JSLE pathogenesis and indicate that further research is required in order to prove whether the rs17849502 polymorphism could be recommended for confirming a diagnosis in JSLE patients.

BACKGROUND The AGER gene encodes a cell surface multiligand receptor of advanced glycation end-products that are also capable of binding other molecules and are involved in numerous pathways related to inflammation, apoptosis, immunity and so on. In this study, we aimed to investigate whether the AGER rs1035798 (G>A) intronic polymorphism, showing an association with multiple sclerosis and rheumatoid arthritis in adults, is related to juvenile idiopathic arthritis (JIA). METHODS Caucasian children from the Belarusian population were enrolled in the study. In total, there were 201 cases with JIA, 37 with juvenile systemic lupus erythematosus, 222 children with the articular syndrome of non-autoimmune etiology (positive control for JIA), and 365 negative controls (children without any autoimmune or inflammatory diseases). Genomic DNA samples from the patients and controls were genotyped by real-time PCR instruments. RESULTS A marked association of the homozygous AA rs1035798 genotype with JIA (p=5×10-4 ) was found. Allele A was also associated with JIA (p=0.0058), as well as with the articular syndrome of non-autoimmune etiology (p=0.0264). The highest frequencies of the AA genotype were found in the subgroups of JIA patients with polyarthritis or severe oligoarthritis. The AA genotype patients also had the smallest mean age of the JIA onset. CONCLUSIONS Our results demonstrate that the AGER rs1035798 AA genotype is a risk factor for JIA in Belarusian children. They also suggest a link between the AGER AA genotype and the risk of JIA early onset and severity. However, the functional relevance of the rs1035798 polymorphism is still unclear.

The study aimed to assess the involvement of three proteasomal genes, PSMA6, PSMC6, and PSMA3, in autoimmune pathogenesis by analyzing associations between single nucleotide polymorphisms and systemic rheumatic diseases with a different autoimmune component: juvenile idiopathic arthritis (JIA), the juvenile form of systemic lupus erythematosus, and Kawasaki's disease (KD). Our results showed that the PSMA6 (rs1048990) polymorphism can be a risk factor for JIA (false discovery rate q ≤ 0.090), while PSMA3 (rs2348071) has a tendency to be nonspecific and is shared with JIA and other autoimmune diseases, including KD, an illness with very low autoimmune activity and high autoinflammation.

The purpose of this investigation has been the analysis of the long-term development of biological damage in natural populations of a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber), which were chronically exposed to low doses of ionizing radiation over 22 animal generations within 10 years following the Chernobyl accident. The time course of the biological end-points (chromosome aberrations in bone marrow cells and embryonic lethality) was compared with the time course of the whole-body absorbed dose rate from external and internal exposure in the studied populations inhabiting monitoring sites in Belarus with different ground deposition of radionuclides. The yield of chromosome aberrations and, in lesser degree, embryonic lethality was associated with the radionuclide contamination of the monitoring areas in a dose-dependent manner. As a main feature of the long-term development of biological damage under low dose rate irradiation, permanently elevated levels of chromosome aberrations and an increasing frequency of embryonic lethality have developed over 22 animal generations. This contrasts with the assumption that the biological damage would gradually disappear since in the same period of time the whole-body absorbed dose rate decreased exponentially with a half-value time of about 2.5-3 years. Furthermore, gravid females were captured, and their offspring, born and grown up under contamination-free laboratory conditions, showed the same enhanced level of chromosome aberrations. Therefore the authors suggest that, along with the biological damage attributable to the individual exposure of each animal, the observed cellular and systemic effects reflect the transgenerational transmission and accumulation, via genetic and/or epigenetic pathways, of damage attributable to the chronic low-dose rate exposure of the preceding generations of animals. They also suggest that the level of the accumulated transmissible damage in the investigated populations will decrease in future due to the further recession of the chronic exposure and as a consequence of selection processes.

Dynamics of population mutagenesis during 22 consecutive generations of animals, as well as genetic radioadaptation were studied in natural populations of small mammals (bank voles) under chronic low‐intensive irradiation due to the Chernobyl accident. The data obtained point to oppositely directed processes in irradiated populations: accumulation of mutations (genetic load of populations) and formation of genetic radioadaptation. It is suggested that the frequencies of genetic damages in populations could be higher in the absence of radioadaptation process. A relationship between the frequencies of cytogenetic injuries and low doses of radiation was revealed in animal generations studied. The non‐linear dose‐effect curves are most likely to be defined by the complicated microevolutionary processes in populations. The results obtained indicate the absence of genetic effect threshold of low dose radiation. Besides, they show that a dependence of cytogenetic effects on radiation low doses in series of irradiated generations cannot be revealed using linear equations.

The time course of the formation of micronucleated polychromatic (MNPCEs) and normochromatic erythrocytes (MNNCEs) in the bone marrow of the bank vole (Clethrionomys glareolus, Schreber), a model mouse-like species, was studied using the standard micronucleus test at 0, 6, 12, 18, 24, 30, 36 and 48 hr following whole-body acute γ-irradiation at a dose of 0.5 Gy. Based on the existing literature on laboratory mice, it was suggested that such a dose will not have significant effect on erythroid cell proliferation in the bank vole and hence on the time course of the rise of micronucleated cells. In total, ∼905,000 polychromatic (PCEs) and normochromatic erythrocytes (NCEs) from 82 adult bank voles were analyzed. Although the mean frequencies of MNNCEs were too low to allow for the correct assessment of their time course, an analysis of PCEs showed an increasing rate of MNPCE appearance at 6 hr that reached a maximum at 18-24 hr after irradiation and subsequently decreased. Because the kinetics of MNPCEs reflects the process of erythropoiesis, the current results regarding the time points of appearance of radiation-induced MNPCEs provide the first information on the prolongation of one of the terminal stages of erythrocyte formation in bank vole specimens, namely the stage of maturation of PCEs from erythroblasts. Moreover, the observed time-course data, as well as the low-background frequencies of MNPCEs and characteristic level of PCEs response to radiation, showed similarities between the two model species: bank vole (this study) and laboratory mice (literature data).

The aim of this pilot study was to assess whether a compound of the β-carbonyl-1,4-dihydropyridine series (AV-153 or sodium 3,5-bis-ethoxycarbonyl-2,6-dimethyl-1,4-dihydropyridine-4-carboxylate), which has high efficiency in stimulating DNA repair, can simultaneously modulate apoptosis in human cells. Peripheral blood lymphocytes of healthy donors were used in this study. DNA strand-break rejoining was assessed with the alkaline comet assay after a 3-h incubation of lymphocytes in the presence of a wide range of concentrations of AV-153 (10−10–10−5 M). Apoptotic and micronucleated (MN) cells were scored in phytohaemagglutinin-stimulated lymphocytes after a 72-h incubation with AV-153, using the standard cytokinesis-blocked micronucleus test. The study revealed dual effects of AV-153 on cellular defense systems against endogenously generated DNA damage: the compound per se simultaneously reduces DNA strand breaks and stimulates apoptosis, with a maximal efficiency of 76% and 42%, respectively; in contrast, after genotoxic stress (2 Gy of gamma-radiation) AV-153 reduces DNA strand breaks, the number of MN cells and apoptotic cells in a similar dose-dependent manner. A maximal efficiency of 67% was found for reduction of DNA strand breaks, while for MN cells and apoptotic cells the efficiencies were, respectively, 47% and 44%. While limited in number, these preliminary studies show the direct correlation between the efficiency of AV-153 in reduction of radiation-induced DNA breaks and MN cells on one side, and in reduction of apoptosis on the other. It suggests that the major target of the compound's action on genotoxic stress is DNA repair, followed by reduction of the number of damaged cells entering apoptosis.

ADP-ribose polymers are rapidly synthesized in cell nuclei by the poly(ADP-ribose) polymerases PARP-1 and PARP-2 in response to DNA strand interruptions, using NAD(+) as precursor. The level of induced poly(ADP-ribose) formation is proportional to the level of DNA damage and can be decreased by NAD(+) or PARP deficiency, followed by poor DNA repair and genomic instability. Here we studied the correlation between poly(ADP-ribose) level and DNA strand break repair in lymphoblastoid Raji cells. Poly(ADP-ribose) synthesis was induced by 100 microM H(2)O(2) and intensified by the 1,4-dihydropyridine derivative AV-153. The level of poly(ADP-ribose) in individual cells was analyzed by quantitative in situ immunofluorescence and confirmed in whole-cell extracts by Western blotting, and DNA damage was assessed by alkaline comet assays. Cells showed a approximately 100-fold increase in poly(ADP-ribose) formation during the first 5 min of recovery from H(2)O(2) treatment, followed by a gradual decrease up to 15 min. This synthesis was completely inhibited by the PARP inhibitor NU1025 (100 microM) while the cells treated with AV-153, at non-genotoxic concentrations of 1 nM-10 microM, showed a concentration-dependent increase of poly(ADP-ribose) level up to 130% after the first minute of recovery. The transient increase in poly(ADP-ribose) level was strongly correlated with the speed and efficiency of DNA strand break rejoining (correlation coefficient ror = 0.92, p0.05). These results are consistent with the idea that poly(ADP-ribose) formation immediately after genome damage reflects rapid assembly and efficient functioning of repair machinery.

Compounds of the 1,4-dihydropyridine (1,4-DHP) series have been shown to reduce spontaneous, alkylation- and radiation-induced mutation rates in animal test systems. Here we report studies using AV-153, the 1,4-DHP derivative that showed the highest antimutagenic activity in those tests, to examine if it modulates DNA repair in human peripheral blood lymphocytes and in two human lymphoblastoid cell lines, Raji and HL-60. AV-153 caused a 50% inhibition of growth (IC50) of Raji and HL-60 cells at 14.9+/-1.2 and 10.3+/-0.8mM, respectively, but did not show a cytotoxic effect at concentrations

As a determinant of the associated health risks, the behavior of radionuclides in natural ecosystems needs to be better understood. Therefore, the activity concentration of various long-lived radionuclides released due to the Chernobyl accident, and the corresponding contributions to the whole-body dose rate, was studied as a function of time in mammalian indicator species inhabiting the natural forest ecosystems of Belarus, the bank vole (Clethrionomys glareolus) and the yellow-necked mouse (Apodemus flavicollus). The activity concentrations of 137Cs, 134Cs, 90Sr, 238Pu, 239,240Pu, 241Pu and 241Am in soil and in animals were measured at five monitoring sites with different ground deposition of radionuclides at different distances from the destroyed reactor. The observed temporal pattern of the radionuclide activity concentration in the studied animal populations reflects the changes in biological availability of these isotopes for biota, mostly due to fuel particle destruction and appearance of dissolved and exchangeable forms of radionuclides. The time course of 134+137Cs activity concentrations in animal populations appeared as a sequence of increase, peak and decrease. Maximal levels of radiocesium occurred 1-2 years after deposition, followed by an exponential decrease. Concentrations of incorporated 90Sr increased up to the tenth year after deposition. The activity concentrations of transuranic elements (238Pu, 239,240Pu, 241Pu and 241Am) were much lower than those of the other radionuclides, in the studied animals. A considerable activity of 241Am in animals from areas with high levels of contamination was firstly detected 5 years after deposition, it increased up to the tenth year and is expected to increase further in the future. Maximal values of the whole-body absorbed dose rates occurred during the year of deposition, followed by a decrease in the subsequent period. Generally, this decrease was monotonic, mainly determined by the decrease of the external gamma-ray dose rate, but there were exceptions due to the delayed maximum of internal exposure. The inter-individual distributions of radionuclide concentrations and lifetime whole-body absorbed doses were asymmetric and close to log-normal, including concentrations and doses considerably higher than the population mean values.