[Radioprotective properties of isothiourea derivatives with NO-inhibitory mechanism of action].

The study of the radioprotective activity of S-[2-alkyl (aryl) sulfonyl]-S-ethyl derivatives of (vinyl)-isothiourea in (he model of the survival of mice exposed to gamma-radiation at a dose of 10 Gy has shown that the incorporation of additional sulfur-containing groups does not increase the radioprotective properties of compounds. In contrast to aminoalkil thiols, the effectiveness of the radiation protection action of the isothiourea (ITU) derivatives studied clearly correlates with the NO-inhibitory activity. This fact allowed us to assume that the radioprotective effect of S-substituted ITU caused inhibition of the endogenous synthesis of NO, which promotes the development of circulatory hypoxia, and that a further search for the radioprotective agents in this class of chemicals should be considered as the search for effective inhibitors of NO-synthase (NOS). The theoretical analysis of the conformity of molecular structures to the composition and topology of the active center of NOS-inhibitors allowed us to prognosticate a number of new ITU derivatives with the potential NOS-inhibiting ability. As a result of further theoretical and experimental studies, four S,N-disubstituted ITU derivatives - active non-selective NOS-inhibitors, were first identified and synthesized. These compounds exhibited a pronounced and prolonged vasopressive effects at doses of 0.01-0.05 LD50/15 in the models of severe hemorrhagic and endotoxic shock, and provided 65-100% 30-day survival at doses of 0.2-0.3 LD50/15 in the mice irradiated by gamma-rays at a dose of 10 Gy (LD98/30).The findings suggest the pronounced radioprotective effect of NOS-inhibitors among the ITU-derivatives.

[Where intestinal epithelial stem cells are localized? About molecular markers].

Using stem cells as an example the review considers a new history and methodology of search for stem cells (SC), found in tissues of adult Homo sapiens and Drosophila melanogaster organisms. These studies of SC resulted in several original hypotheses explaining their unusual features. Impressive progress recently achieved in this direction (2008-2010) is associated with employment of new methods of somatic recombination for long-term registration of various strains of differentiated cells, early and distant SC progeny. 1) Although anatomic localization of intestinal epithelium cells lacking marked morphological and biochemical differentiation markers (the lower third of intestinal and colon crypts) is known for about 40 years results of their experimental identification, isolation and detection of their functional characteristics still represent the subject for discussions. Particularly, it remains unclear, which SC are involved in crypt regeneration: the same as those involved into homeostatic renewal or their various subpopulations or early SC progenies acquired stem features by reprogramming? 2) In addition, most detected biochemical markers of potential SC are common for SC from other tissues of embryonic and mature organisms so it is possible to apply method developed for intestinal epithelium for their isolation. 3) Data on induction of intestinal epithelium polyps and neoplasias by mutations in genes encoding SC markers and identification of biochemical characteristics of potential SC in these tumors support the hypothesis of stem tumor cell origination from normal SC or their earliest progeny. In general, facts considered in this review may be useful for both development of optimal methods for the use of SC in cell therapy (as the source of humoral factors), regenerative medicine (as the source of differentiated cells for restoration of injured tissue), and also for targeted search of antitumor drugs (SC as the target) and preparations modifying genetic and epigenetic reactions of SC to genotoxic and stress treatments.

[Antiradical and NO-inhibiting activities of bet-hydroxy(ethoxy) derivatives of nitrous heterocycles].

The antiradical and NO-inhibiting activities of beta-hydroxy(ethoxy) derivatives of nitrous heterocycles (3-hydroxypyridine, 5-hydroxybenzimodazole, and 6-hydroxy(alkoxy)-benzothiazole) have been studied. The antiradical activity has been studied using a homogeneous hydrophilic chemiluminescent system, and the quenching constants (Ki) have been determined. For the most reactive compound, 4-methylthiobenzimidazolyl-3-hydroxypyridine, Ki = 4.5 x 105 M(-1). The NO-inhibiting activity was estimated on a model of the endotoxin shock of experimental animals using a spin trap of nitric oxide radicals based on complexes of iron with sodium diethyldithiocarbamate. It was found that the compounds at doses of 0.25-1 mmol/kg have both the inhibitory and stimulating action on the production of nitric oxide in the liver of animals. The results obtained suggest that some derivatives of nitrous heterocycles can be used as effective antioxidant preparations.

[Stem cells of intestine epithelium. Survival mechanisms and microbiota role].

The thanatogenetic mechanisms of stem cells (SC) of rapidly renewing system of intestinal epithelium still remain unclear. On the one hand, they are definitely involved into basic mechanisms of carcinogenesis in the gastrointestinal tract, because dysregulation of programs responsible for elimination of "unwanted" mutant cells (which are normally under immune and own intrinsic control) is one of the reasons of neoplastic expansion. On the other hand, elucidation and characterization of the regulatory machinery controlling SC survival are interrelated with problems of clinical medicine, including the increase of therapeutic efficiency of treatment of inflammatory and ulcer lesions of the gut, traumatic and surgical wounds, as well as restriction of side effects in normal tissues induced by application of intensive methods chemo- and radiotherapy of cancer. The latter is especially important for treatment of blood diseases and tumors of peritoneal cavity organs mainly due to bone marrow and intestinal epithelium damage. (These tissues are the most sensitive to these treatments.) The review considers data on exogenous and genetic modifiers of SC survival, and also the basic principles of mechanisms involved into renewal and regeneration of SC and the effects of microbiota on these processes.

[Survival/death modifiers of intestine epithelium stem cells and thanatological mechanisms].

Till now the thanatological mechanisms that regulated the proliferation and the clearance of the stem cells (SC) in fast renewal systems of organism--intestinal epithelium remain insufficiently investigated as in haematopoietic system too. The relevance of such researches is supported by an essential role of these mechanisms in pathogenesis of widely widespread inflammatory and hyperproliferative diseases. In particular inhibition/disregulation of elimination for the "undesirable", mutant cells leaving from under immune and own control is one of the reasons for neoplastic cell expansion. In this review were summarized data about some mechanisms determining SC-destruction in animals treated by ionizing radiation or antineoplastic preparations, and also treated by modifiers of SC-radiosensitivity.

[The influence of some retarding agents NOS of dihydrothiazine-thiazoline rank on postradiational of recovery endogenous CFU-S-8 of mice].

In this work the attempt to estimate a nitric oxide (NO*) role in regulation of the number of pool haemopoietic stem cells at the irradiated mice was made. With this purpose the number of new compounds from dihydrothiazine-thiazoline line was synthesized, their NO-inhibiting activity was investigated in vivo by the method of ESR-spectroscopy of spin trap and their influence on an output endogenous spleen colonies (CFU-S-8) after the total sublethal y-irradiation of mice in a doze of 6 Gy was also investigated. Was shown, that the tested compounds reduced the contents of NO* in a liver tissue of mice which have received an injection of nitric oxide synthesis inductor - lipopolysaccharide, and also increased an output CFU-S-8 forming endogenous colonies in the spleen of the irradiated mice. Received data testify to perceptivity of search radioprotective agents among NO* synthesis inhibitors.

[The correlation between intracellular level of nitric oxide and frequency of gene somatic mutations after low dose radiation exposure].

The purpose of this work was the study of possible relationship between intracellular NO level and somatic mutagenesis after irradiation with low doses. The level of NO in peripheral blood lymphocytes and frequency of the TCR-mutant cells were assessed by flow cytometry in 64 workers of atomic industry with mean dose (+/- SE) 114.9 +/- 10.8 MSV, accumulated within 21.4 +/- 1.1 years, and 66 age- matched control donors. The mean frequency of the TCR-mutant cells in this groups was (6.1 +/- 1.0) x 10(-4) and (4.1 +/- 0.2) x 10(-4) respectively (p = 0.06). 14% of workers of atomic industry had the TCR-mutant cell frequencies exceeding the 95% confidence interval in control donors. It was found the positive correlation between the intracellular NO level and the TCR-mutant frequency (R = 0.36, p < 0.01). The mean level of NO in individuals with the elevated TCR-mutant frequency was significantly higher than in others: 1619 +/- 57 vs 1340 +/- 40 relative units (p = 0.01). The results suggest that nitric oxide may come into elevating frequency of the mutant cells in some proportion of individuals exposed to low doses of ionizing radiation not excepting formation of genome instability.

["Ischemia/reperfusion" for stem cells of two "critical" cell renewal systems of organism].

In this article is presented the result of the experiments on mice-hybrids F1(CBA x C57B1/6), which indicates the presence of the reaction of "ischemia/reperfusion" for stem cells of two "critical" cell renewal systems of organism (bone marrow and intestinal epithelium) during the irradiation under the conditions of hypoxic radioprotector application. The additional injection of the source of nitric oxide radicals-sodum nitroprusside (SNT) to the mice right after the irradiation under the conditions of hypoxic protection by serotonin, resulted the substantial increase of the survival rate of hematopoietic stem cells (registered by the methods of endogenous and exogenous colony forming in spleen) and stem cells of intestinal epithelium (registered by the method of intestinal "microcolonies"). The similar radioprotective effect was also registered during the test of survival rate of mice under tests of "bone marrow" and "intestinal" forms of radiation lethality that is evidence of the importance of the realization of phenomenon "ischemia/reperfusion" in the reaction of whole organism on the acute radiation injury. As SNP weakens the manifestation apoptosis and necrosis through competition with active forms of oxygen (AFO) during the period of "reperfusion" on basis of the found out phenomenon experimental model for studying mechanisms of stem cells damage in vivo induced by AFO and for the search of the modifiers weakening or strengthening such damage can be developed.

[The estimation of the nitric oxide role in the aggravation of combined radiation-thermal injuries].

The influence of specific inhibitor of inducible NO synthase S-ethil-isothiourea (as "Difetur" preparation) on liver NO production level, and 30-days survival, mean survival time and probability of mortality within animals under combined radiation/thermal injury (CRTI) were evaluated. Experiments were carrying out on mice (whole body gamma-irradiation at the dose of 7 Gy + 10% body surface full-thickness thermal burn). It was shown, that CRTI induce 2-fold statistical significant increase of NO production in liver of experimental animals. Mice pretreatment with Difetur preparation lead to practically full inhibition of NO production. In the group of animals, with Difetur administration during first two days after CRTI 60% mice survived as compared 15% survive in control group. In pair with data on probability of mortality it was suggested that growth of NO production in the early period of CRTI increase sensitivity of animals to pathological processes leading to death on 10-12 days.

[Ageing and necrotic form of "unwanted" cells]. / Starenie i nekroticheskaia forma éliminatsiia "nezhelatel'nykh" kletok.

Collecting experimental data testify that cellular necrosis is the same component of "unwanted" cell system elimination in a metaphyte, as well as apoptosis. The essential role of the last in definition of rates of ageing is expressed, in particular, in secretion by phagocytes of the factors overwhelming inflammatory reactions which are rather characteristic for such illnesses as an atherosclerosis, a diabetes and others. Apparently, infringement of balance between necrotic and apoptotic forms "unwanted" cell elimination from an organism can be the important factor of ageing and the reason of reduction of life expectancy as a result of supression of renewal processes in an organism, occurrence and weights of development of some senile illness.

[NO-inhibiting activity of radioprotectors]. / NO-ingibiruiushchaia aktivnost' radioprotektorov.

The effect of radioprotectors of different structure on the syntheses of nitric oxide induced by endotoxin in mice was studied. Using ESR-spectroscopy and spin trap techniques, it was shown that compounds of different chemical structure, such as aminothiols, isothiuronium derivatives, thiazolines, indolylalkylamines and others, suppressed the nitric oxide production in a whole body. The analysis of the relevant literature has confirmed the phenomenon described by the authors: radioprotectors show NO-inhibiting activity.

[The effect of an injection of N-methylformamide into mice on the cell cycle and cell morphology of ascitic hepatoma 22A]. / Vliianie in''ektsii mysham N-metilformamida na kletochnyi tsikl i morfologiiu kletok astsitnoi gepatomy 22A.

A cell differentiating agent N-methylformamide (MF) was studied for its antitumor activity against a murine ascitic hepatoma 22A. After a 48 hour NMF administration (i/p) the tumor cell number was monitored; the distribution of these cells in the cell cycle was registered by flow cytometry, ultrastructural changes were studied by electron microscope. The polar solvent MF inhibited tumor growth, reduced mitotic activity, and nuclear/cytoplasmic ratio, led to structural complication of endoplasmic reticulum and mitochondria. The analysis of these events is suggestive that in consequence of MF effect on tumor cells, proportion of G0/G1 and M cells was decreased, while the proportion of S and G2 cells was increased.

[A modification in the radiation reaction of normal and tumor tissues in mice induced by N-methylformamide]. / Modifikatsiia radiatsionnoi reaktsii normal'nykh i opukholevykh tkanei myshei N-metilformamidom.

The effect of potential differentiation-inducing agent N-methylformamide on radiation response of murine normal and tumor cells (Lewis lung carcinoma, hematopoietic tissue and jejunum epithelial stem cells) was studied. The agent reduced or not altered radiation damage of tumor and epithelial cells in mice receiving NMF before irradiation. Sensitization to radiation was observed in endogenous spleen colony forming hemopoietic stem cells. When the agent was injected 15 min before irradiation the sensitizing effect was less pronounced. The highest effect was observed when agent was injected 24 h after irradiation of animals.

[The effect of unithiol on the antineoplastic and antimetastatic activity of N-methylformamide]. / Vliianie unitiola na protivoopukholevuiu i antimetastaticheskuiu aktivnost' N-metilformamida.

Antitumor and antimetastatic properties of N-methyl formamide--an agent related to differentiation of tumoral cells and unithiol, official detoxicating drug containing SH-groups were studied in C57Bl/6 mice inoculated with Lewis's lung carcinoma. The drugs were administered intraperitoneally into animals at days 1, 4, 7, 13 and 16 after carcinoma inoculation and their effects were evaluated at day 19. Single administration of unithiol, 5 mg/kg body weight, did not affect tumor growth and metastases spreading. At the same time, N-methyl formamide (single administration of 300 mg/kg body weight) inhibited tumor growth and decreased 5-fold an amount of spontaneous metastases in lungs. However, the antitumor and antimetastatic activities of N-methyl formamide were decreased after simultaneous administration with unithiol. Importance of SH-groups in therapeutic effects of N-methyl formamide is discussed.

[Distribution of beta-carotene in the rat upon its intraperitoneal administration in water soluble and oil forms]. / Raspredelenie beta-karotina v organizme krys pri ego vnutribriushinnom vvedenii v vide vodorastvorimoi i maslianoi form.

Accumulation and excretion of beta-carotene in rat liver tissue were studied when the carotinoid was intraperitoneally administered as olive oil as suspension and a water liposomal suspension. Single injection of the liposomal form of beta-carotene caused an increase in its content in liver tissue. If beta-carotene was administered at a dose of 10 mg/kg its maximal content 44 mg/g of the tissue was observed within one day, and at a dose of 50 mg/kg, its maximal content constituted 178 mg/g within two days. Administration of beta-carotene as an oil suspension at a dose of 50 mg/kg led to a considerably slight accumulation in rat liver tissue with the maximal value of 12 mg/kg of the tissue within two days. Possible use of beta-carotene various forms, as well as experimental models for study their biological activity are discussed.

[The inhibition by the tumor necrosis factor of the death and DNA fragmentation of lymphoid cells in irradiated rats]. / Ingibirovanie faktorom nekroza opukholi gibeli i fragmentatsii DNK limfoidnykh kletok obluchennykh krys.

The influence of a tumor necrosis factor, administered 16 h before irradiation of rats, on the radiation response of thymus and bone marrow cells has been investigated. Three and 6 h after irradiation the following indices were analyzed: the number of apoptotic cells in the thymus; the accumulation of polydeoxyribonucleotides and the appearance of single-strand breaks in DNA of bone marrow and thymus cells; and the electrophoretic properties of thymocyte DNA. The injection of a tumor necrosis factor reduced the number of polydeoxyribonucleotides, inhibited internucleosome DNA fragmentation, and did not influence the formation of single-strand breaks in DNA.

[The possible participation of protein SH groups and aldehydes in radiation damage of cell membranes]. / O vozmozhnom uchastii belkovykh SH-grupp i al'degidov v radiatsionnom povrezhdenii kletochnykh membran.

The sedimentation method was used to study the effect of N-ethylmaleimide, diethyl maleate, formaldehyde, Ca2+, and dithiothreitol on cell membranes. Sedimentation quality of erythrocytes was shown to be modified by the agents that bound protein SH-groups and aggregated proteins.