The paper is concerned with the counting of aberrant cells and chromosome aberrations in the 1st mitosis in PHA stimulated lymphocytes of the peripheral blood of healthy donors following gamma-beam irradiation in vitro at a dose of 1-5 Gy and in lymphocytes of the peripheral blood and bone marrow of patients with acute leukemia (in remission) after therapeutic whole-body gamma-beam irradiation at a dose of 1.5-5 Gy (doses to the "body center"). After irradiation in vitro and in vivo regression equations for each studied cytogenetic index (percentage of cells with dicentrics, the frequency of dicentrics and dicentrics + centric rings) were the same in form but differed in coefficients. The distribution of dicentrics by cells at all doses was in conformity with Poisson's law. It was shown that the radiosensitivity of the peripheral blood lymphocyte chromosomes in healthy donors and leukemic patients (in remission) was approximately the same.

DNA from human breast carcinoma (SK-BR-3) and neuroblastoma (LA-N-1) cell lines are capable of inducing foci of transformed NIH 3T3 cells after DNA-mediated gene transfer. The blot hybridization analysis of DNA from primary and secondary NIH 3T3 transformants identified additional sequences homologous to the c-Ha-ras 1 oncogene, and revealed amplification of nucleotide sequences homologous to the v-myc oncogene. Restriction fragments of the amplified myc-related sequences correspond to c-myc (SK-BR-3) and N-myc (LA-N-1) loci of the human genome. The results show that active Ha-ras oncogenes can coexist with altered myc oncogenes in breast carcinomas and neuroblastomas. This suggests that a multi-step mechanism involves both ras and myc genes and their cooperation in the development of these tumors.

Two kappa genes, one (5.7 kb) from parental myeloma cells that were used for fusion, and the other (7.5 kb) from lymphocytes have been detected in the genome of PTF.02 hybridoma. Functionally important regions of the second gene were sequenced. In the 5'-region, positions and nucleotide sequences of the L-fragment, TAATA- and CAAT-boxes were established. Deca (dc)- and pentadecanucleotide (pd) sequences, obligatory for effective transcription of Kappa genes, were localized at the distance of 91 and 118 bp from the ATG initiating codon of the leader sequence. Together with a true pd, a shadow pd sequence was localized. This sequence was overlapped with the first sequence and shifted by one helical twist. The structure of the region of the enhancer localization was established. Comparison of this sequence with known consensus of the papova virus enhancer allows us to suggest the following structure of the enhancer core for kappa chains: TGTGGCTAA... 10 bp... TGTGGTTA. In the kappa gene under study, the variable fragment is linked to the J5 segment. In the latter, a point mutation C----G was found, to which a conservative substitution Ala - Gly in a hypervariable region of the chi-chain should correspond. Somatic mutations were also observed within the intron region adjacent to the J5 segment.

The effect of tumour promoter, 12-0-tetradecanoylphorbol-13-acetate (TPA), on the cloning efficiency of different clones of mouse tumour cells was studied in semi-solid medium. The clones varied in their response to TPA. Inhibition and inherited stimulation of colony-formation efficiency in semi-solid medium was revealed. One clone did not respond to TPA. The influence of environmental factors on the clone structure and tumour progression is discussed.

Using leukemic P-388 cells, it was demonstrated that alterations of the intracellular Na+/K+ ratio results in qualitative changes of newly synthesized mRNA, which manifests itself as changes in the kinetics of hybridization of heterogeneous nuclear RNA (hnRNA) with DNA. The decrease of the Na+/K+ value from 3.8:1 to 1:1 leads to inhibition of mRNA synthesis in mRNA cells hybridized at 10(3) greater than Dot greater than 10(4), but weakly affects the transcription of mRNA sequences hybridized with DNA within the Dot interval of 10(3.4)-10(3.8). A similar phenomenon is observed during hybridization of hnRNA with homogeneous fractions of unique and averagely repeating sequences of DNA. The hybridization rate constants of hnRNA synthesized by cells at different values of Na+/K+ and the limit values of hybridization (H infinity) were calculated. It was shown that the rate constants for RNA hybridization with DNA decrease by more than two orders of magnitude during the transition of the averagely repeating DNA fraction to the unique one; however, in both cases these constants give equal values for the RNA synthesized by cells at different cationic balance. The H infinity values for the RNA synthesized by cells at higher Na+ ratio appeared to be 1.5-2.0 times as high as compared with those for the RNA in the cells, in which the Na+/K+ ratio was 1:1. Thus, the monovalent cation ratio seems to exert a strong influence on the expression of sequences of different repeatedness in the genome and to play a role in the regulation of proliferative activity of the cell.

Study in the variability and heritability of the "radiosensitivity" character in clone populations of rhabdomyosarcoma RA-2 and carcinosarcoma K10 in rats has shown a hereditary heterogeneity of the clonogenic tumour cell populations by the given character and probability of the facultative threshold display.

The possibility of using the LDH as a marker of hereditary predisposition to the stomach cancer was analysed by using the genetical correlational analysis. The LDH isoenzymes in the gastric body were studied in 56 pedigrees. Similar LDH alterations were detected in relatives with cancer and precancer (ulcer disease, atrophic gastritis). Relatives with no such pathology had LDH isoenzymes, similar to the control individuals. High and significant coefficients of phenotypic and environmental correlation of LDH and predisposition to the stomach cancer were obtained. The coefficient of genetic correlation was not significant. The problem of the origin of these LDH variances is discussed. The preliminary conclusion is that the LDH isoenzyme changes revealed in patients with stomach cancer appear as a consequence of the disease, and cannot be used as the marker of hereditary predisposition.

Data obtained from karyotyping and estimation of nucleolar organizer (NO) activity in bone marrow cells from 9 patients with multiple myeloma (MM) and from 8 donors are presented. Chromosomes of the 14th and 1st pairs in patients with MM are confirmed to be more frequently involved in rearrangements. It is proved that activity of NO in myeloma cells is rather high as compared to that of erythroid and granulocyte cells, that is associated with their participation in paraprotein synthesis.

The karyological study of 10 mouse hybridomas revealed that all cells in two hybridoma clones, as well as in two subclones isolated from the third hybridoma, contained specific clonal biarmed markers, atypical for myeloma parent cells X63.Ag8.653. The proportion of cells with additional new meta- and submetacentric markers, which were different in the cells of the same culture, reached 0.38-0.56 in some of the hybridomas under study. The above biarmed chromosomes were, probably, formed as the result of the centromeric fusions of subtelocentrics. The presence of identical new biarmed chromosomes in all cells in some hybridoma cultures could be attributed to the fact that all these cells originated from a single initial cell, already containing such marker (or markers). The results of the cytogenetic analysis may confirm the monoclonal origin of a considerable part of mouse hybridomas.

It was shown that after UV-irradiation of Ehrlich ascites tumor cells with doses suppressing DNA replication, DNA-protein cross-links were mainly predominantly in the nuclear matrix as compared to peripheral chromatin. A modified method of determining DNA-protein cross-links in the nuclear matrix preparations is proposed.

Heredity predisposition was analysed in cancer and precancer stomach diseases in distinct populations. Some phenotypic and genetic characters of the stomach "precancer--cancer" system were studied. Similarity in the degree of stomach cancer inheritance, its segregation frequency and recurrent risk was revealed for populations. However, the degree of correlation between cancer and precancer stomach disease was different in distinct populations, this being more pronounced in "cancer--gastric ulcer" system.

In vitro thymidine histoautoradiography was employed to measure labeling index in 18 moderately- and well-differentiated adenocarcinomas of the rectum before and after radiotherapy. After radiation labeling index fell from 13.8 +/- 3.2 to 3.9 +/- 1.4% while mitotic index--from 8 to 1%.

DNA samples obtained from tumors and adjacent mucosa of the large bowel of a patient with large bowel multiple neoplasia were examined after Southern. The procedure established amplification of v-myc oncogene-related DNA sequences in 1 out of 5 tumors tested. Restriction fragments of amplified myc-specific sequences and matching c-myc and N-myc loci of the human genome differed in size.

A study of individual and family histories of 200 ovarian cancer patients and 200 healthy controls was concerned with evaluation of 274 factors of risk. It yielded 36 most informative ones. An 80% credibility of screening results was demonstrated when a combination of characteristics was used. Decision rule is recommended as a test for formation of a group at high risk.