[Transcription map of the 13q14 region, frequently deleted in B-cell chronic lymphocytic leukemia patients]. / Transkriptsionnaia karta raiona 13q14, chasto utrachivaemogo u bol'nykh B-kletochnym khronicheskim limfoleikozom.

Deletions in the region located between the STS markers D13S1168 and D13S25 on chromosome 13 are the most frequent genomic changes in patients with B-cell chronic lymphocytic leukemia (B-CLL). After sequencing of this region, two novel candidate genes were identified: C13orf1 (chromosome 13 open reading frame 1) and PLCC (putative large CLL candidate). Analysis of the repeat distribution revealed two subregions differing in composition of repetitious DNA and gene organization. The interval D13S1168-D13S319 contains 131 Alu repeats accounting for 24.8% of its length, whereas the interval GCT16C05-D13S25, which is no more than 180 kb away from the former one is extremely poor in Alu repeats (4.1% of the total length). Both intervals contain almost the same amount of the LINE-type repeats L1 and L2 (20.3 and 21.24%, respectively). In the chromosomal region studied, 29 Alu repeats were found to belong to the evolutionary young subfamily Y, which is still capable of amplifying. A considerable proportion of repeats of this type with similar nucleotide sequences may contribute to the recombinational activity of the chromosomal region 13q14.3, which is responsible for its rearrangements in some tumors in humans.

[Features of DNA repair during chronic exposure to mutagenic factors]. / Osobennosti reparatsii DNK pri khronicheskom vozdeistvii mutagennykh faktorov.

Long-time in vivo influence of chemical mutagens in low doses can decrease the level of unscheduled DNA synthesis (UDS) induced in human as well as in laboratory mammals. The phenomenon under investigation is not specific neither for chronically acting mutagens nor for challenging agent. A decrease in UV- and gamma-ray-induced UDS was registered after chronic irradiation in plant populations and also in Chernobyl ameliorators and inhabitants of radioactively contaminated regions. The observed effect seems to have general biological character.

[The cytogenetic effects in persons who suffered as a result of the accident at the Chernobyl Atomic Electric Power Station]. / Tsitogeneticheskie éffekty u lits, postradavshikh v rezul'tate avarii na Chernobyl'skoi AES.

Frequency of chromosome aberration was evaluated in 537 persons taken part in amelioration after the accident. The highest rate of aberration was found in covering builders and dosimetric: 3.24 +/- 0.25 and 3.11 +/- 0.43 per 100 cells, respectively. The mean rate of aberrations among the Chernobyl NPP staff was 2.37 +/- 0.20 per 100 cells, in the other examined groups the mean yield of aberration varied from 1.31 to 1.47 per 100 cells. The found aberration rates correspond to the equivalent whole body doses in the range from 131 to 515 mGy as evaluated by the established dose-response curve. In the group of covering builders the individual aberration rates varied more markedly, and corresponded to the equivalent whole body dose up to about 1 Gy. Slides of 27 individuals were checked by an automated dicentric scoring system. The results showed a satisfactory correlation between the frequencies of dicentrics per chromosome detected by routine and computer methods.

[UV-induced unscheduled DNA synthesis in the peripheral blood lymphocytes of participants in the clean-up of the aftereffects of Chernobyl accident]. / UF-indutsirovannyi vneplanovyi sintez DNK v limfotsitakh perifericheskoi krovi uchastnikov likvidatsii posledstvii Chernobyl'skoi avarii.

The dependence of UV-induced unscheduled DNA synthesis on UV exposure dose was studied in intact donors and persons dealt with liquidation of the Chernobyl accident consequences in 1986-1990. In the group of persons exposed to high doses the decrease in the level of UV-induced unscheduled DNA synthesis and the increase in the level of spontaneous one was registered.

[The dose dependence of the induction of chromosome aberrations in those who worked in the cleanup of the Chernobyl accident]. / Dozovaia zavisimost' induktsii khromosomnykh aberratsii u likvidatorov Chernobyl'skoi avarii.

The method of biological dosimetry based on registration of frequency of chromosome aberrations in peripheral lymphocytes was proven to be a valuable technique for estimation of large absorbed doses. In the case of low absorbed doses or low dose rate the suitability of this method is restricted because of deficiency of suitable dose-response curve for yield of chromosome aberrations. In this work chromosome aberration rate was estimated in 31 ameliorators of the Chernobyl accident with the known data of physical dosimetry in the range of 12-30 cGy. Linear dependence of induction of chromosome aberrations was found in this dose range. The coefficients for induction of dicentrics and all unstable aberrations of chromosome type was found to be 1.4 +/- 0.4 and 7.2 +/- 1.2 per 100 cells per 1 Gy, respectively.