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T A Lezhava

Publications and source records attributed to T A Lezhava.

At least 19 recordsLinked to original sources
PubMed2005

[Chromosome instability in patients with different forms of cardiomyopathy and their relatives].

Comparative studies on spontaneous and induced by two agents (mytomycin C and Nickel chloride) chromosome instability have been conducted in cultured lymphocytes derived from patients with hypertrophic and dilated forms of cardiomyopathy (HCMP and DCMP) and their relatives compiling a high-risk group to develop mentioned pathologies. In patients with HCMP and DCMP, as well as in their relatives higher levels of spontaneous chromosome instability were found in comparison with the control group (comprising healthy individuals without cardiomyopathic anamnesis). Almost all the affected patients and their relatives revealed tendency to increased aneuploidy and significant elevation of polyploidy when compared with control values. It was demonstrated that nickel chloride-induced chromosome disorders registered more frequently in lymphocytes of the patients and their relatives than in cells of control subjects, but mytomycin C did not have such an affect. We assume to explain the similarity of studied parameters in patients with cardiomyopathy and their relatives as a consequence of identical rearrangements in genome functioning. The revealed analogy should be interpreted as a pre-illness condition for the individuals included in the risk-group.

Aneuploidy↗
PubMed2004

Effects of short peptides on lymphocyte chromatin in senile subjects.

Effects of synthetic short peptides (Vilon, Epithalon, Livagen, Prostamax, and Cortagen) on activity of ribosome genes, parameters of common heterochromatin melting, polymorphism of structural heterochromatin (C segments) of chromosomes 1, 9, and 16, and variability of facultative heterochromatin were studied in leukocytes of subjects aged 75-88 years. All the studied peptides induced activation of ribosome genes, decondensation of densely packed chromatin fibrils, and release of genes repressed as a result of age-specific condensation of the cellular euchromatin regions (deheterochromatinization of facultative chromatin). Treatment with Epithalon, Livagen, and Prostamax led to decondensation of chromosome 1 pericentromeric structural chromatin, while Epithalon and Livagen treatment led to changes in chromosome 9 as well. Hence, short peptides activate heterochromatin and heterochromatinized regions of cell chromosomes in senile subjects.

Aged↗
PubMed2002

Effects of Livagen peptide on chromatin activation in lymphocytes from old people.

We studied the effects of the synthetic peptide Livagen on activity of ribosomal genes, denaturation parameters of heterochromatin, polymorphism of structural C-heterochromatin, and variability of facultative heterochromatin in lymphocytes from old people. Livagen induced activation of ribosomal genes, decondensation of pericentromeric structural heterochromatin, and release of genes repressed due to age-related condensation of euchromatic regions in chromosomes. Our results indicate that Livagen causes de-heterochromatinization (activation) of chromatin, which is realized via modification of heterochromatin and heterochromatinized regions in chromosomes from old people.

Aged↗
PubMed2001

[Human chromosome functional characteristics and aging].

The MUTATION level (chromosome aberrations covering telomere regions), MODIFICATIONS of CHROMOSOME STRUCTURE (level of condensed chromatin identified by the methods of electron microscopy and differential scanning microcalorimetry; level of C-banding constitutive heterochromatin; transcriptional activity of DNA-dependent RNA polymerase; Ag-positive NORs and associations of acrocentric chromosomes) and REPARATION (intensity of unscheduled DNA synthesis and the frequency of sister chromatid exchanges) have been studied in lymphocyte cultures from individuals at the age of 70-114 to reveal the chromosome functional organization at late stages of ontogenesis and to find explanations of some senile pathologies. The analysis of obtained results showed: 1) chromosome progressive heterochromatinization (condensation of eu- and heterochromatin regions) occurs at aging; 2) decrease of repair processes and increase in frequency of chromosome aberrations in aging are secondary to the progressive heterochromatinization. Chromosome heterochromatinization is a key factor of aging; 3) chromosome heterochromatinization may be the reason for some senile pathologies; 4) chromosome heterochromatinization is an area where one should seek the ways for prolonging the lifespan.

Aging↗
PubMed1994

[Structural mutations of chromosome mutations induced by heavy metal salts during aging in vivo and in vitro].

The cytogenetic effect of inorganic copper (CuSO4) and cadmium (CdCl2) salts was studied in cells of long-term (144-hour) human cultures (in vitro model of aging) and in elderly individuals (80-93 years old). Copper sulfate increased the incidence of aberrant cells both in elderly individuals (14.25 +/- 1.74%) and during in vitro aging (12.20 +/- 1.62%) (3.94 +/- 1.96% and 5.25 +/- 1.10% in the controls, respectively), whereas treatment with cadmium chloride did not induce any changes in the background index. Differences in the effect of the studied salts may be due to their different effects on chromatin modification.

Adolescent↗
PubMed1989

[Characteristics of the cis- and trans-positions of chromatids of human acrocentric chromosomes in extreme old age].

Cis- and trans-positions of chromatid associations of human acrocentric chromosomes were examined at extreme old age. Lymphocyte cultures were prepared by the usual method, from peripheral blood of 9 subjects aged 80-90 years (analysis of 179 metaphases) and 7 subjects aged 20-48 years (analysis of 124 metaphases). The functional difference between stalks of the sister chromatids was found. In the subjects at the age 80-90 years satellite stalks of chromatids-1 (in all DNA strands thymidine was substituted by 5-BrdU) of the D chromosome in cis-position are included into associations with lower frequency, as compared with the satellite stalks of chromatids-2 (thymidine+ is only substituted by 5-BrdU in a half DNA strands of the chromosome). This apparently reflects variability of regulation of functional activity of satellite stalks of sister chromatids.

Adult↗
PubMed1984

Heterochromatinization as a key factor in aging.

An analysis of observations on modifications during aging of the characteristics of chromosomes during the mitotic cycle of their mutations and unscheduled aging leads to the conclusion that enhanced heterochromatinization during aging prevents the action of reparative enzymes, and results in increased numbers of cells with chromosomal aberrations.

Adult↗
PubMed1984

The activity of nucleolar organizer regions of human chromosomes in extreme old age.

Ag-positive nucleolar organizer regions (NORs) and associations of silver-stained acrocentric chromosomes were studied in 400 metaphases from 20 male and female subjects aged 20-50 and 80 or over. The number of Ag-positive NORs and the frequency of chromosome associations were found to be decreased significantly at 80 and thereafter in comparison with middle age. The use of G stain revealed a significant age-dependent decline in the numbers of argent-affine 13th and 21st chromosomes and the frequency of associations formed by the 13th and 22nd chromosomes. These phenomena seem to be determined by heterochromatinization of satellite stalks of the 13th, 21st and 22nd chromosomes during aging.

Adult↗
PubMed1982

[Sister chromatid exchanges in human lymphocytes in extreme old age].

After the treatment with 5-bromodeoxyuridine (BrdU), the frequency of sister chromatid exchanges (SCE) in the lymphocyte culture cells of peripheric blood tends to be lower in very aged persons, from 80 to 88 years (7.69 +/- 0.34), than in middle aged ones (8.40 +/- 0.33). The reliable decrease in SCE level was assessed in chromosomes A1 and C from the old group persons as compared with the appropriate values in the middle age group. The level of SCE falls in telomeric and centromere regions of chromosomes A1 and A2.

Adolescent↗
PubMedDate not supplied

[Human acrocentric chromosomal associations in old age].

Associations of satellite chromosome fibres of acrocentric chromosomes of the DD, GG and DG types were studied in persons aged from 80 to 114 years. It was found that the value of P (probability of joining of satellite fibres of two chromosomes in a group) is considerably less than the corresponding value for persons aged from 20 to 48 years. It is supposed that the decrease of the frequency of association at senile age is caused by heterochromatization of satellite fibres in the 13th and 14 chromosome pairs.

Adult↗