Radioprotective and Radiomitigative Effects of Melatonin in Tissues with Different Proliferative Activity.

We used various markers to analyze damage to mouse tissues (spleen and cerebral cortex) which have different proliferative activity and sensitivity to ionizing radiation (IR). We also assessed the degree of modulation of damages that occurs when melatonin is administered to mice prior to and after their X-ray irradiation. The data from this study showed that lesions in nuclear DNA (nDNA) were repaired more actively in the spleen than in the cerebral cortex of mice irradiated and treated with melatonin (N-acetyl-5-methoxytryptamine).

Increase of mtDNA number and its mutant copies in rat brain after exposure to 150 MeV protons.

Proton beam therapy is widely used for treating brain tumor. Despite the efficacy of treatment, the use of this therapy has met some limitations associated with possible damage to normal brain tissues located beyond the tumor site. In this context, the exploration of the harmful effects of protons on the normal brain tissues is of particular interest.

Assessment of Nuclear and Mitochondrial DNA, Expression of Mitochondria-Related Genes in Different Brain Regions in Rats after Whole-Body X-ray Irradiation.

Studies of molecular changes occurred in various brain regions after whole-body irradiation showed a significant increase in terms of the importance in gaining insight into how to slow down or prevent the development of long-term side effects such as carcinogenesis, cognitive impairment and other pathologies. We have analyzed nDNA damage and repair, changes in mitochondrial DNA (mtDNA) copy number and in the level of mtDNA heteroplasmy, and also examined changes in the expression of genes involved in the regulation of mitochondrial biogenesis and dynamics in three areas of the rat brain (hippocampus, cortex and cerebellum) after whole-body X-ray irradiation. Long amplicon quantitative polymerase chain reaction (LA-QPCR) was used to detect nDNA and mtDNA damage.

Metformin prolongs survival rate in mice and causes increased excretion of cell-free DNA in the urine of X-irradiated rats.

An antidiabetic drug metformin has anticarcinogenic and geroprotective effects and has been used in combination with radiation cancer therapy. The present work is devoted to the study of the effect of metformin on survival in mice, the frequency of micronuclei in mouse bone marrow cells and excretion of cell-free nuclear and mitochondrial DNA in the urine of X-ray-exposed rats. The survival rate and the frequency of micronuclei in mice and excretion of DNA into rat urine were determined after administration of the drug before and after irradiation of animals.

X-rays and metformin cause increased urinary excretion of cell-free nuclear and mitochondrial DNA in aged rats.

Activation of cell death in mammals can be assessed by an increase of an amount of cell-free DNA (cf-DNA) in urine or plasma. We investigated the excretion of cf nuclear DNA (nDNA) and cf mitochondrial DNA (mtDNA) in the urine of rats 3 and 24 months in age after X-irradiation and metformin administration. Analyses showed that prior to treatment, the amount of cf-nDNA was 40% higher and cf-mtDNA was 50% higher in the urine of aged rats compared to that of young animals.

[Technical features of intestinal ureteroplasty. Part 7: forming ureterointestinal anastomoses].

Aim: To present the results and technical features of forming the ureterointestinal anastomoses in intestinal ureteral substitution.

Material And Methods: From 1998 to December 2016, 168 patients (mean age 51 +/- 8.7 years) underwent ureteral substitution using intestinal segments at the Urology Clinic of the I.

[Technical features of intestinal ureteroplasty. part 5: bilateral ureteroplasty].

Aim: To present the results and the technical features of the various methods of bilateral ileal ureteroplasty.

Materials And Methods: From 2001 to 2016, 154 patients (mean age 52+/-9.2 years) underwent ileal and appendicular substitution of the ureter and urinary bladder.

[Technical features of intestinal ureteroplasty. Part 2: right-sided ileoureteroplasty].

Aim: To present the results of intestinal ureteroplasty and technical features of right-sided ileoureteroplasty.

Material And Methods: From 2001 to 2015, 78 patients underwent isolated reconstruction of the ureter using a segment of the ileum, of whom 57 (73%) and 21 (27%) patients had unilateral and bilateral operation, respectively. In total, isolated segments of the ileum were used to substitute 101 ureters including 45 (44.

Regeneration and Cicatrization.

Cicatricial tissue, being the local center of sclerosis, replaces the wound or focus of cell death. Scarring is caused by various types of injuries, including operations, as well as by a number of diseases. Scarring often culminates in the formation of strictures and other complications.

Cell-free DNA in the urine of rats exposed to ionizing radiation.

Investigation of cell-free DNA (cf-DNA) in body fluids, as a potential biomarker for assessing the effect of ionizing radiation on the organism, is of considerable interest. We investigated changes in the contents of cell-free mitochondrial DNA (cf-mtDNA) and cell-free nuclear DNA (cf-nDNA) in the urine of X-ray-exposed rats. Assays of cf-mtDNA and cf-nDNA were performed by a real-time PCR in rat urine collected before and after irradiation of animals with doses of 3 and 5 Gy.

[On the prospects of using the DNA repair inhibitors in radiotherapy of tumors].

The cellular DNA repair systems sufficiently provide the resistance of tumors to ionizing radiation, and thus contribute to reducing the effectiveness of their radiotherapy. Therefore, suppression of the activity of critical DNA repair enzymes in tumor cells is considered one of the promising directions to overcome this resistance. As can be seen from the literature analysis, the use of many inhibitors of DNA repair enzymes have not yet yielded the results, which can be extrapolated to preclinical models or clinical trials.

Mitochondrial function and mitochondrial DNA maintenance with advancing age.

We review the impact of mitochondrial DNA (mtDNA) maintenance and mitochondrial function on the aging process. Mitochondrial function and mtDNA integrity are closely related. In order to create a protective barrier against reactive oxygen and nitrogen species (RONS) attacks and ensure mtDNA integrity, multiple cellular mtDNA copies are packaged together with various proteins in nucleoids.

[Experimental detection of integration of mTDNA in the nuclear genome induced by ionizing radiation].

Transfer of mtDNA in the nuclear genome is usually regarded as a continued and dynamic process of forming numt-pseudogenes or numt-insertions. They can be regarded not only as a neutral polymorphism, but may be involved in oncogenesis, aging and genetic diseases. Experimental identification of numt-insertions arising de novo is limited due to the presence of numerous homology mtDNA constitutively existing in the nuclear genomes of eukaryotes.

[Pathways for maintenance of mitochondrial DNA integrity and mitochondrial functions in cells exposed to ionizing radiation].

The analytical review deals with the results of studies devoted to mitochondrial DNA (mtDNA) disorders, the development of oxidative stress and possible pathways for the maintenance of mitochondrial functions in cells exposed to ionizing radiation (IR). Mitochondrial functions, which are closely related to the integrity of mtDNA, play a key role in many cellular processes. A wide range of degenerative diseases, carcinogenesis, and aging is associated with disturbances in mtDNA.

[Variability of DNA simple sequence repeats in peripheral blood of humans subjected to prolonged exposures of ionizing radiation].

Long-term post-radiation changes in the level of microsatellite DNA polymorphism in peripheral blood of the male "Mayak" employees (Ozyorsk, Russia), who had been exposed to prolonged gamma-irradiation during professional activities, were studied. DNA samples were obtained from the Radiobiology Repository of Human Tissue (Southern-Urals Biophysics Institute FMBA) and used as templates for arbitrarily primed PCR. Comparative analysis of the obtained samples of DNA fragments showed a significant increase in the number of high-molecular fragments and reduction in the number of amplified low molecular weight DNA fragments in comparison with the control.

[Changes of mitochondrial DNA/nuclear DNA ratio in the blood serum following X-ray irradiation of mice at various doses].

Using quantitative real-time PCR, the copy number of mitochondrial and nuclear DNA fragments in mouse blood serum was estimated at different time points following X-ray irradiation at various doses (from 0.5 to 10 Gy). The changes in the correlation between mtDNA and nuclear DNA (mtDNA/nucDNA) in blood serum reflect the degree of radiation injury depending on the dose of irradiation.

[Low efficiency of repair of critical DNA damage induced by low doses of radiation].

This study provides an analysis of the development of cellular response to the critical DNA damage and the mechanisms for limiting the efficiency of repairing such damages induced by low doses of ionizing radiation exposure. Based on the data of many studies, one can conclude that the majority of damages occurring in the DNA of the cells after exposure to ionizing radiation significantly differ in their chemical nature from the endogenous ones. The most important characteristic of radiation-induced DNA damages is their complexity and clustering.

[Increased genomic instability in somatic cells of the progeny of female mice exposed to acute X-radiation in the preconceptional period].

The level of genome instability (GI) was studied in the progeny of female mice exposed in the preconceptional period to radiation doses of 0.5, 1, and 2 Gy in comparison to that in the progeny of the same parent pairs born before irradiation of the females. To assess the level of genome instability, we analyzed polymorphism of DNA fragments from postmitotic (blood and brain) and proliferating (spleen and tail tip) tissues amplified by AP-PCR (PCR amplification with an arbitrary primer).

[Delayed and transgenerational molecular and genetic effects of prolonged influence of ionizing radiation in nuclear plant workers].

Genome variability and changes in immune homeostasis, induced in man in the course of long-term industrial contact with ionizing radiation (IR) sources were studied by using unique biomaterials stored in the Radiobiological Repository for Human Tissues at the Southern Urals Biophysics Institute, FMBA. The biomaterials, peripheral blood samples and blood DNA were obtained from the "Mayak" PA employers occupationally exposed to prolonged external gamma-radiation and/or internal alpha-radiation from incorporated 239Pu in a wide range of accumulated doses. A significant increase in the polymorphism of microsatellite-associated peripheral blood DNA repeats was revealed in a group of persons with accumulated doses of external gamma-radiation above 2.

[Share of extracellular mutated mitochondrial DNA increases in plasma of lung cancer patients following radiotherapy].

Quantitative and qualitative changes in circulating extracellular DNA (ec-DNA) of blood plasma are considered as markers for diagnosis and prognostic of tumor pathology. We investigated the content of mutant copies of the circulating extracellular mitochondrial DNA (ec-mtDNA) in blood plasma (using the enzymatic method, based on the cleavage of DNA with unpaired bases by CEL-I endonuclease) in 8 patients with lung cancer before and after radiotherapy, as well as in healthy young and elderly donors. It was found that in the plasma of healthy elderly donors share of ec-mtDNA with mutations (consisting of total circulating DNA) is much greater, than that of young donors.

Alteration of mtDNA copy number, mitochondrial gene expression and extracellular DNA content in mice after irradiation at lethal dose.

High steady-state transcriptional activity is essential for normal mitochondrial function. The requisite transcription rate is satisfied in part by high copy number of mitochondrial DNA (mtDNA). In the present study, we analyze mtDNA copy number by real-time PCR in nucleated blood cells from control mice and mice exposed to 1- or 10-Gy X-radiation.

[Mutant copies of mitochondrial DNA in tissues and plasma of X-rays exposed mice].

With violations of the mitochondrial genome associated wide range of degenerative diseases, the development of tumor pathology, aging and the processes of cell death. We investigated the levels of mitochondrial DNA (mtDNA) with mutations and their total content in the tissues of the brain, and spleen of mice exposed to X-rays at doses of 1-5 Gy, and depending on the post-radiation time (8-28 days). These same mice were analyzed for the level of mutant copies of the extra cellular mtDNA (ec-mtDNA) and its total content in blood plasma.

[Nuclear mitochondrial pseudogenes].

Transfer of genetic material from mitochondria to the nucleus and their integration into the nuclear genome is a continuous and dynamic process. Fragments of mitochondrial DNA (mtDNA) in the nuclear genome are incorporated as non-encoded sequences, which are called nuclear mitochondrial pseudogenes (NUMT-pseudogenes). At present, the formation NUMT-pseudogenes in the nuclear genome is shown in many eukaryotes.

[Extracellular mutant mitochondrial DNA content is sharply elevated in the blood plasma of irradiated mice].

Nucleic acids circulating in blood plasma and other biological fluids may be of interest as potential markers for diagnosis of various pathologies and monitoring of stress influences. For many genotoxic agents, mitochondrial DNA (mtDNA) is a more vulnerable target than nuclear DNA, and mutations of mitochondrial genome may be markers of many diseases. In the present study extracellular mtDNA with mutations was determined in the blood plasma of mice exposed to X-radiation at a dose of 5 Gy.

[Reduction of the number of mutant copies of mitochondrial DNA in tissues of irradiated mice in the postradiation period].

Changes in the number of mutant copies of mitochondrial DNA (mtDNA) were studied in the brain and spleen tissues of mice after their X-irradiation at a dose of 5 Gy. For this purpose, heteroduplexes obtained via hybridization of the products of PCR amplification of mtDNA (ND3 gene and two D-loop regions) from irradiated and control mice were digested with the CelI nuclease capable of specific mismatch cleavage. Heteroduplexes obtained via hybridization of the products of PCR amplification of mtDNA from irradiated and control mice were digested by the CelI nuclease to a greater degree than heteroduplexes of the PCR products of mtDNA of mice from the control group.