[Studying pathogenesis of Alzheimer's disease in a Drosophila melanogaster model: human APP overexpression in the brain of transgenic flies leads to deficit of the synaptic protein synaptotagmin].

Alzheimer's disease (AD) is a progressive neurodegenerative disease whose main pathomorphological sign is synapse degeneration in the cortex and hippocampus. Abnormal synaptogenesis precedes amyloidosis and neurodegeneration and correlates with memory impairment during the early clinical phase. Mutations in the amyloid precursor protein (APP) gene cause familial AD and enhance the secretion of amyloid-beta-protein (Abeta). However, it remains unclear in what way APP and Abeta are involved in synaptic disorder in the absence of visible amyloid structures. In this study, the role of the human APP gene in synaptogenesis in transgenic lines of Drosophila melanogaster whose nerve cells express the human APP695 isoform, truncated APPs, and the presynaptic marker synaptotagmin driving the sequence of the green fluorescent protein. The expression of APP and its truncated forms caused a decrease in the synaptotagmin content of antennal lobes and mushroom lobes of the D. melanogaster brain, as well as neurodegeneration that progressed with age. The results suggest that that abnormal synaptogenesis and neurodegeneration occur in the Drosophila brain in the absence of Abeta. It is assumed that impaired cellular functions of APP and secretion of Abeta independently contribute to the pathogenesis of AD.

[The influence of sodium nitrite on the osmoresistance of Chinese hamster cells].

We have previously demonstrated that incubation of V-79 cells in the medium containing the nitric oxide donor, NaNO2, increases cell resistance to damaging effect of gamma-rays, UV radiation and hyperthermia. In the present study, we investigated the effects of the nitric oxide donor on the sensitivity of V-79 cells to changes in osmomolarity of the medium by adding different amounts of sodium chloride or water. We found that pretreatment of the cells with NaNO2 resulted in a significant increase in the number of growing cells in 48 h after the treatment. The osmomolarity-dependent morphological changes in cultured cells were also substantially diminished following NaNO2 treatment. This effect could be observed under both hyper- and hypoosmosis, and was dependent on concentration of sodium chloride in hypertonic medium (being maximal under 0.17 M NaCl) and on the amount of water in hypotonic medium (being maximal under 1.1 times the dilution with water). In the experiments with increased osmomolarity, we found that the observed increase in the number of growing cells following NaNO2 treatment was accompanied with a significant increase of the mitotic index. These findings indicate that nitric oxide increases cell resistance to the damaging effects of osmotic shock in the way which is similar to the protective effect of these molecules against radiation and hyperthermia. Similarities in the effects of NaNO2 under different conditions leading to cell damage suggest that nitric oxide might serve as the universal factor participating in recovery of damaged cells and mediating increased cellular resistance to the damaging conditions.

[The influence of nitric oxide inductor (NaNO2) on the sensitivity of Chinese hamster cells to hyperthermia].

Formerly we reported the reduction of sensitivity to gamma- and UV-radiation in Chinese hamster cells of line 90 under the influence of nitric oxide inductor (NaNO2). Of interest was to learn if it possible to reduce the influence of hyperthermia on cells by means of NO inductor. A 1 h long incubation with this NO donor demonstrated an increased survival of cells heated up to 45 degrees C, and a decreased frequency of chromosomal aberrations in these. Employment of cycloheximide (CHE), an inhibitor of protein synthesis, and administration of CHE together with nitric oxide donor (NaNO2), equally increased the cell survival at hyperthermia. These and relevant literature data suggest that the demonstrated effect of exogenous NO may be associated with HSP70 protein. The noticed decrease in the number of chromosomal aberrations in heated cells under the influence of NO donor may play an important role in its modifying effect on cells at hyperthermia.

[Decrease of toxic effects of aminothiol radiation-protective agents and increase of chemical protection action against ionizing radiation by the use of unithiol]. / Snizhenie toksicheskogo deistviia aminotiolovykh radioprotektorov i povyshenie éffekta khimicheskoi zashchity ot ioniziruiushchei radiatsii s pomoshchiu unitiola.

It has been shown that unithiol diminishes toxic action of cysteamine, AET, and disulfide of WR-1065 on mice. This permits to enhance protection of animals against X-rays by increasing of protector doses. The effect of unithiol on cysteamine action in rats was the same. Antitoxic effect of unithiol on cysteamine was shown both at i.p. and p.o. protector administration. The effect was also revealed in Chinese hamster V-79 cell culture. Combined disulfide of cysteamine and unithiol was synthetized, which ensures effective prolonged protection against ionizing radiation.

[Cellular reactions induced by chronic exposure to 14C beta-rays]. / Kletochnye otvety, indutsirovannye khronicheskim oblucheniem beta-chastitsami, ispuskaemymi pri raspade 14C.

In V-79 cells the Effects of chronic exposure on induction of chromosome aberrations and abnormal metaphases as well as on efficiency of subsequent exposure to 2 Gy gamma-rays were investigated. It was found that chronic exposure increased the yield of chromosome aberrations as well as abnormal metaphases (spread-metaphases and apoptotic metaphases). In spite of the level of damages in cells, the chronic beta-exposure protected cells against the additional induction of chromosomal aberrations by subsequent exposure to higher acute dose of gamma-irradiation. Cytogenetic adaptive response was retained in the surviving progeny of irradiated cells which were cultured in free medium during 40, 70 days or one year after chronic exposure. At this time the level of residual chromosome aberrations, colony forming ability and distribution of the cells by the number of chromosomes were almost the same as in unirradiated cells. However, the high level of abnormal metaphases and half as much of cells in colony in the surviving progeny of irradiated cells in comparison with unirradiated cell, allow us to suggest that the chronic exposure induced the selection of adaptive forms in condition of the higher level of radiation.

[Characterization of the adaptive response to the action of gamma-rays, induced by low doses of 14C in Chinese hamster fibroblasts]. / Kharakteristika adaptivnogo otveta k deistviiu gamma-luchei, indutsirovannogo malymi dozami 14C v fibroblastakh kitaiskogo khomiachka.

It has been studied the correlation of the mitotic activity of the chromosome aberrations and apoptosis, in the V-79 cells pre-exposure to an adapting dose of ionizing radiation from 14C-thymidine prior to an acute challenge dose of gamma-rays. In spite of that the incubation of the cells with isotope increased of the yield of the chromosome aberrations, but the cells became more resistant to following gamma-irradiation. Increasing the adaptive dose of the 14C on degree didn't influence on the present of the adaptive response. However, using concentrations of the 14C damaged metaphase/anaphase transition and cells blocked in this check-point by apoptotic death. The results suggest, that the cellular selection has been involved in 14C-induced adaptive response, estimated by level of asymmetric chromosome aberrations in V-79 cells.

[Effect of nitric oxide donor (NaNO2) on the stability of non-transformed and malignant cells to ultraviolet and gamma-radiation]. / Vliianie donora oksida azota (NaNO2) na ustoichivost' netransformirovannykh i zlokachestvenno pererozhdennykh kletok k ultrafioletovomu i gamma-izlucheniiam.

A decreased sensitivity of the Chinese hamster cells (line V-79) to gamma-radiation under the influence of nitric oxide induction was shown elsewhere. This effect is connected hypothetically with post-radiation reparation of DNA. The investigation of the nitric oxide donor effect on sensitivity of these to UV-radiation is of interest, because this radiation is an important ecological factor of the environment. The question of retention of nitric oxide positive effect on UV and gamma-radiation sensitivity in malignant HeLa cells is no less actual, because these cells significantly differ from normal cells of line V-79. We demonstrated that the donor of nitric oxide enhances stability of the Chinese hamster cells (line V-79) to UV-radiation, as well as to gamma-radiation independently of the time of cell incubation with sodium oxide donor before or after irradiation. The inefficiency of nitric oxide as a factor increasing UV-stability of cells was shown for malignant HeLa cells. A 1 h long incubation of these cells with NO-donor before gamma-irradiation decreased the number of chromosome aberrations, and conversely, the addition of this agent to the HeLa cell culture after gamma-irradiation did not change the radiostability. It may be inferred that distinctions in behaviour of nitric oxide in cultures of V-79 and HeLa cells using UV-radiation may be explained by transformation of the latter special features of their damage, and by the following reparation.

[Protein transduction domain peptide mediates delivery to the brain via the blood-brain barrier in Drosophila].

Protein transduction domain (PTD)-peptides greatly facilitate the delivery of high molecular weight macromolecules across the blood-brain barrier (BBB). This BBB-transport function is highly desirable and helps to enable the development of new therapeutics for treatment of brain disorders. However, the drug discovery process is limited by the generation of a simple and reliable BBB model that is amenable to testing of large number of samples and simultaneously, reproduces the physiological and functional characteristics of the human BBB. To address these challenges, we have studied whether the PTD-peptide penetratin, derived from a Drosophila Antennapedia homeodomain protein, is capable of crossing the BBB in Drosophila while carrying a cargo into the fly brain. An initial in vivo experiment in Drosophila showed that abdominal injection of biotin-tagged penetratin permeated the BBB. The same effect was observed for biotin-tagged penetratin fused with apoE mimetic peptide with demonstrated anti-inflammatory and neuroprotective activities.

[Repair of chromosome damage in human lymphocytes after fractionated irradiation with fast neutrons]. / Reparatsiia povrezhdenii khromosom limfotsitov cheloveka pri fraktsionirovannom obluchenii bystrymi neitronami.

The frequency of chromosome aberrations in nonstimulated lymphocytes of the peripheral human blood was shown to change after fractionated neutron irradiation of mean energy of 6.0 MeV. At a 2-hour interval between exposures, the number of aberrations exceeded, and at 5-6-hour interval was less than that induced by a single exposure at the same dose.