[Diagnostics of ataxia-telangiectasia by the express-test found on the method of indirect immunofluorescence].

Ataxia-telangiectasia (AT) is a hereditary severe neurodegenerative disease developing, when mutations take place in both alleles of the atm gene, which encodes the key protein of the cellular response to DNA damage (DDR)--ATM proteinkinase. In response to the occurrence of double-strand DNA breaks, the ATM proteinkinase pass the autophosphorylation, and its active form--the phospho-ATM (P-ATM) appears in cells. In the nuclei of cells having the atm gene, P-ATM is revealed, being absent in cells with mutated forms of this gene, by means of the application of the modified method of indirect immunofluorescence. This peculiarity may be applied in the clinic, in order to confirm the diagnosis of AT.

[Age dymamics of stable chromosome aberration frequency in humans with natural and pathological senescence]. / Vozrastnaia dinamika chastoty stabil'nykh khromosomnykh aberratsii u cheloveka pri estestvennom i patologicheskom starenii.

The age dynamics of stable chromosome aberration (SCA) frequency was analysed by fluorescent in situ hybridization (FISH) in human blood lymphocytes derived from donors, irradiated by low doses of ionizing radiation (Chernobyl clean-up workers, nuclear weapon testers, etc.) and patients with hereditary premature aging--Werner's syndrome and Hutchinson-Gilford's syndrome. It was found that the level of SCA was age-dependent and increased in irradiated persons. So, the SCA level may be really an index of a so-called "radiation senescence", and may show a real biological age of irradiated persons. The patients with Werner's syndrome demonstrate increased SCA level in blood lymphocytes, corresponding to the premature aging of the organisms. But in the case of another form of premature aging--Hutchinson--Gilford's syndrome-- no rise of SCA level was found. Some possible reasons of such results are discussed.

[Cytological and molecular changes in the atypical case of accelerated human aging]. / Tsitologicheskie i molekuliarnye izmeneniia pri netipichnom sluchae uskorennogo stareniia cheloveka.

A complex research of cells of a patient with unusual form of premature ageing was made. The clinical picture is not typical for any of known forms of hereditary premature aging--progerias. Skin fibroblasts of the patient AG has limited proliferation capacity in vitro. It was shown by fluorescent-immunochemical hybridization (FISH-method), that the level of stable chromosome aberrations in AG blood lymphocytes was characteristic of aged 55-65 years, though as he was only 26 years old. Some characteristic peculiarities, typical for progerias, were found in the reaction of skin fibroblasts of AG to growth factors addition. Some clinical and biochemical peculiarities are results rather, than reasons of the disease. The conclusion is that the premature ageing in this case is a manifestation of Werner's syndrome--one of hereditary forms of accelerated senescence.

[The isolation and analysis of lymphoblastoid cell lines from patients with xeroderma pigmentosum and progeria]. / Poluchenie i analiz limfoblastoidnykh kletochnykh linii ot bol'nykh pigmentnoi kserodermoi i progeriei.

Lymphoblastoid cell lines from patients with xeroderma pigmentosum (2 forms) and progeria (unusual form) were established using transformation of peripheral blood lymphocytes by Epstein--Barr virus. The influence of different UV doses on cell vitality, proliferation and cell cycle progression was studied by means of flow cytometry. The cell vitality was determined after incubation of cells with etidium bromide and FDA. We used cytograms with two logarithmic signals (log green/log red) to discriminate the cell cycle status. Cell cultures were used with density of 500,000 cells per 1 ml, previously synchronized at G-phase by the incubation in a medium with low serum content. The effect of UV irradiation was followed during 72 h. Among four analysed cell lines only line XP2SP demonstrated enhanced UV sensitivity, expressed by decreasing of the amount of living cells after the UV dose of 2.5 J/m2 and higher. The cell cycle studies showed that cells were blocked in S-phase and simultaneously the amount of apoptotic cells with both reduced DNA content and ability to bind FDA was seen increased. Similar events were observed in the control line only after the dose of 20 J/m2 and higher.

[The results of a cytogenetic examination performed in different years on those who worked in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station]. / Rezul'taty tsitogeneticheskogo obsledovaniia likvidatorov posledstvii avarii na ChAES, provedennogo v raznye gody.

Persons participated in the Chernobyl accident amelioration in the years of 1986-1987 were examined cytogenetically either in 1987 (group 1) or in 1990-1992 (group 2). The frequency of chromosome aberrations in cultured peripheral lymphocytes is found to be significantly lower in group 2 in comparison with group 1, being increased in both exposed groups as compared to the control one. The data are obtained in favour of hypothesis on chromosome instability of exposed individuals. On the base of cytogenetic data the collective dose received by amelioraters was calculated.

[DNA replication in intact and X-ray-irradiated cells in the Cockayne syndrome]. / Replikatsiia DNK v intaktnykh i obluchennykh X-luchami kletkakh pri sindrome Kokeina.

Using DNA fiber autoradiography, an estimation was made of DNA replication in normal fibroblasts and in those derived from a patient with Cockayne syndrome. The rate of replication fork movement as well as the rate of DNA chain growth, dependent on the frequency of initiation sites in the adjacent clusters of replicons, did not differ in Cockayne syndrome cells, compared to cells of normal donors, either before or after exposure to ionizing radiation.

[Radioresistant DNA synthesis in the fibroblasts of a Down's syndrome patient]. / Radiorezistentnyi sintez DNK v fibroblastakh bol'nogo sindromom Dauna.

DNA synthesis after gamma-irradiation was analysed either by direct assay of the amount of 3H-Td incorporated into DNA of fibroblasts derived from normal donor and from a patient with Down's syndrome, or by analysis of the steady-state distribution of 3H-DNA in alkaline sucrose gradients. Doses of gamma-radiation that markedly inhibited the rate of DNA synthesis in normal human cells caused almost no inhibition in fibroblasts of the patient with Down's syndrome. The radioresistant DNA synthesis in cells of this patient was mainly due to a much less inhibition of replicon initiation than that in normal cells. Thus, in the case of Down's syndrome, the cells fail to go through the delays during which DNA lesions can be repaired, unlike the situation being the case in normal cells.

[Occurrence and elimination of single- and double-stranded DNA breaks in the fibroblasts of xeroderma pigmentosum patients exposed to gamma radiation]. / Vozniknovenie i likvidatsiia odno- i dvunitevykh razryvov DNK v fibroblastakh bol'nykh pigmentnoi kserodermoi pri gamma-obluchenii.

A defect in ability to rejoin gamma-induced single-strand DNA breaks, earlier found in the lymphocytes of a patient with form II of xeroderma pigmentosum, has been also shown for cultured skin fibroblasts. In successive subcultivation the ability to rejoin DNA breaks gradually increases. Elimination of double-strand DNA breaks occurs with the same fullness and rate as in the cells of patients with classic form of XP and healthy donors. The subcultivation does not influence this process. Possible causes of the phenomena discovered are discussed.

[DNA repair in the UV irradiation of human peripheral blood lymphocytes (healthy donors and xeroderma pigmentosum patients) in relation to the dedifferentiation process in phytohemagglutinin exposure]. / Reparatsiia DNK pri UF-obluchenii limfotsitov perifericheskoi krovi cheloveka (zdorovykh donorov i bol'nykh pigmentnoi kserodermoi) v sviazi s protsessom dedifferentsirovki pod vozdeistviem fitogemaggliutinina.

UV-induced unscheduled DNA synthesis has been studied in lymphocytes of healthy donors and of Xeroderma pigmentosum patients (the classic form, and a form with an increased sensitivity to gamma-ray). In order to study the influence of PHA-induced differentiation on repair capacity of cells, lymphocytes were cultured in the presence or in the absence of PHA. The data obtained show that PHA-induced differentiation of human lymphocytes leads to an increase in the intensity of repair after UV-irradiation of these cells, and, accordingly, the repair is completed in a shorter time. In the case of the classic form of Xeroderma pigmentosum, the effect of differentiation on the repair level is more distinct, but no effect is observed in cells of Xeroderma pigmentosum sensitive both to UV and gamma-ray.

[Cellular DNA repair, proliferative activity and biochemical characteristics in the human premature aging syndrome (progeria)]. / Reparatsiia DNK, proliferativnaia aktivnost' i biokhimicheskie osobennosti kletok pri sindrome prezhdevremennogo stareniia (progeriia).

Fibroblasts of a patient with the Hutchinson-Gilford progeria show a decreased proliferative activity in culture and run through no more than 19 subcultivations. Progeria cells rejoin gamma-induced single strand DNA breaks to the same extent and with the same rate as do normal cells. Spontaneous and induced by X-ray chromosome aberration frequency in progeria cells does not differ from that in normal cells. The activity of DNA-polymerases alpha, beta and gamma in different way depends on culture conditions in progeria and normal cells, but no expressed deficiency of these enzymes was found in progeria cells. The activity of easy-soluble arginine-specific proteases in progeria fibroblasts is sharply decreased, and sensitivity of proteins in these cells to trypsin-catalyzed hydrolysis is significantly increased compared to that of normal cells. Defect in the turnover of intracellular proteins is considered to be a reason of a rapid accumulation of altered proteins in cycling cells and a possible reason of accelerated ageing of progeria cells in vitro.

[Weakening of the ultraviolet ray-induced unscheduled DNA synthesis in human lymphocytes in extreme old age]. / Oslablenie indutsirovannogo ul'trafioletovymi luchami vneplanovogo sinteza DNK v limfotsitakh cheloveka v glubokoi starosti.

The intensity of unscheduled DNA synthesis was studied in UV-irradiated (10--15 J/m2) peripheral blood lymphocytes of 80--90 years old persons. In these extreme old age persons, reparative DNA synthesis was found sufficiently reduced in comparison with that in middle aged (20--43 years old) ones. The role of DNA repair processes in ageing is under discussion.