Search

Repair DNA synthesis (RDS) in human fibroblasts during the adaptive responses (ARs) induced by cadmium chloride (CdCl2), gamma-radiation, and 4-nitroquinoline-1-oxide (4NQO) was compared in cells pretreated and not pretreated with garlic extract. The RDS was increased during the ARs induced CdCl2 and gamma-irradiation. Garlic extract stimulated RDS in cells treated by the same mutagens. 3-Aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) polymerase, decreased the RDS rate in cells treated with CdCl2 and gamma-irradiation but had no significant effect on cells treated with 4NQO. It was demonstrated that DNA repair was involved into cell protection in different ways in the cases of antimutagen treatment and AR.

Two lines of fibroblasts isolated from patients with homocystinuria were characterized by the test of vaccinia virus host-cell reactivation. Xeroderma pigmentosum cells and normal fibroblasts were used as a control. Reduced host cell reactivation of the virus and an enhanced level of induced virus mutations in comparison with normal cells were revealed in homocystinuria cells after 4NQO and gamma-ray treatment. Enhanced reactivation and a corresponding reduced level of gamma-induced mutagenesis were found in preirradiated normal cells and in the xeroderma pigmentosum cells. The level of enhanced reactivation of the virus was virtually the same in preirradiated and nonirradiated homocystinuria cells, while the level of induced mutagenesis was reduced in both cells. This indicates the difference in the capability of the virus system for enhanced reactivation to repair potentially lethal and premutational DNA damages.

The repair activity of DNA was studied by variola vaccine virus reactivation and induced mutagenesis tests in the peripheral blood lymphocytes of children living in areas with an increased level of ionizing radiation due to breakdown at the Chernobyl' nuclear power station. A more profound repair disturbance was revealed in children living on strictly controlled territories and born after the disaster, compared to those born before it, and children living in areas where the radiation level does not exceed background values. The disturbances were characterized by increased induced mutagenesis and decreased reactivation of the variola vaccine virus. No changes in the degree of DNA repair synthesis were registered in any of the groups studied.

Radioadaptive response in cells from three patients was studied by induction of structural chromosome aberrations. Radioadaptive response was revealed in lymphocytes of all three patients. Coefficient of protection was 59.0% and did not differ from this after cell pretreatment with interferon. It is suggested the similarity or identity of mechanism of radioadaptive response and of interferon antimutagenic action which was implemented by non-repair way.

Adaptive repair is the restoration of chemically induced DNA breaks in human fibroblasts previously gamma-irradiated at low doses. The adaptive repair in xeroderma pigmentosum (XP) cells was compared to that in normal human fibroblasts. The obtained results suggest that the repair is inducible and error-free. Adaptive repair was not found in XP cells in experiments with 4-NQO. This is correlated with the presence of an excision repair defect in XP.

Natural leucocyte interferon (IF) upon injection to two patients affected with Xeroderma pigmentosum for three weeks stimulated the inhibited DNA replication and Host reactivation at the level of healthy donors. Tigasol--the drug used traditionally for the treatment of diseases caused by Xeroderma pigmentosum proved less effective than IF.

The workers contacting with cobalt chloride for 10 years and more have been receiving 50 mg ascorbic acid for 30 days. DNA repair was analysed after this procedure in lymphocytes cultivated in vitro according to following criteria: reactivation and induced mutagenesis of vaccinia virus as well as formation of DNA breaks and their resynthesis upon treatment with cobalt chloride and 4-nitro-quinoline-1-oxide.

DNA repair was explored in continuous cells withdrawn from gout patients. The data obtained were compared to those on primary cells (lymphocytes) from the same patients. Two continuous lines of fibroblasts obtained from the biopsy material of patients suffering from gout were examined for stability of reparation defects on long cell passage. The studies were made with 4 to 12 passages of patients' fibroblasts. The use of criteria reflecting certain stages of DNA repair (reparative synthesis of DNA, formation of induced DNA ruptures and their resynthesis during cell postincubation, reactivation and induced mutagenesis of measles vaccine virus in patients' cells) allowed confirmation of repair defect stability in gout patients' cells on their long passage. Based on the data on preservation of the repair defect on cell passage it is concluded that gout patients demonstrate the genetically determined impairment of the synthesis of DNA repair enzymes participating in the recovery of DNA impairments induced by UV radiation or UV mimetics.

Increased level of cytogenetic damages was observed in lymphocytes of 10 patients with muscular dystrophy (Duchenne, Erba, Landuzi--Degerin). Analysis of DNA repair synthesis revealed inhibition of this process in lymphocytes of 10 patients observed. On the other hand, decreased reactivation of vaccinia virus and increased level of virus mutagenesis induced by 4-nitroquinoline-1-oxide and bleomycin was noted in the experiments with lymphocytes of 3 patients observed.

Cells of various murine lines were shown to be suitable models for the study of the mutagenesis of vaccinia virus and other DNA viruses. The virus may be an indicator of the reparative activity of the cells.

Repair disorders of DNA damage induced by gamma-radiation and 4-nitroquinoline-1-oxide treatment in cultivated lymphocytes of patients with schizophrenia. 13 criteria were used for estimation of repair activity (reactivation of viral host cells) repair synthesis, reparation of DNA breaks, formation of spontaneous and induced sister chromatid exchanges.

DNA repair activity in cells after gamma-irradiation or treatment with 4-nitroguinoline-1-oxide was studied by alkaline elution of cells lysed on membrane filters, as well as by reactivation and induced mutagenesis of vaccinia virus in lymphocytes and fibroblasts obtained in skin biopsy from patients with homocystinuria. Disorders of the repair were demonstrated in lymphocytes by using both criteria. In all fibroblast passages repair disorder was only found for gamma-irradiation, the repair activity being comparable with that of lymphocytes. The level of spontaneous and gamma-induced mutations in vaccinia virus propagated in fibroblasts was increased at later culture passages.

Lymphocytes of two patients with Xeroderma pigmentosum, their mothers and cell lines isolated from the third patient were examined. The reaction of vaccinia virus treated with mutagens, the index of virus-induced mutagenesis and DNA repair synthesis were the criteria of estimation of cell repair activity. Significant inhibition of DNA repair synthesis was detected in cells of all the patients observed (primary and established lines) in the experiments with UV-irradiation and 4-nitroquinoline-4-oxide. These indexes correlated with decreased virus reactivation and increased level of virus-induced mutagenesis. Inhibition of DNA repair synthesis was also revealed in lymphocytes of both mothers. These data claim a possibility of discovering heterozygotes, the carriers of mutant genes. The data on virus-induced mutagenesis serve as a simple test for detection of DNA repair disorders.

A study was made of the processes of repair, virus reactivation, and formation of sister chromatid exchanges (SCE) in blood cells of patients with schizophrenia after the effect of gamma-radiation and 4-nitroquinoline-1-oxide. These processes were estimated by 12 criteria. The mutagen-induced disturbances in the processes of repair and SCE formation were found in cells of patients with schizophrenia and were absent in the control cells of healthy donors.

Lymphocytes of patients with gouty nephropathy were investigated using the criteria of sister chromatid exchanges (SCE) formation, rapidity of generation, virus reactivation, detection of the level of virus mutagenesis and DNA repair and replication synthesis in the experiments with some mutagens. Disorders, according to these criteria, were observed in the cells of all the patients. Cells of patients with gouty nephropathy may be used as a model to study DNA repair and replication mechanisms.

Repair processes in blood lymphocytes of children with hereditary homocystinuria have been studied. The identical results on the defective repair processes of damaged DNA were received by the two methods used. The method of vaccinia virus reactivation registered total disturbance of the repair function in cells, while the method of alkaline elution revealed the defects in the enzymes providing resynthesis of DNA breaks in normal conditions.

As many as 8 families suffering from gout were examined with the use of four tests for the repair of DNA damages. The criteria applied for the assessment of the reparative activity made it possible to identify in total or in different combinations the inhibition of the repair in the lymphocytes of all the probands examined. The use of 1-3 procedures revealed the repair defects in all the families, namely in the lymphocytes of the probands' relatives. Based on this fact an attempt has been made to identify possible carriership of the "pathological" genes in the proband's relatives, which in future will make it possible to develop approaches to the identification of the genetic markers of the disease as well as to the disease prevention.

Employing the appropriate technique the authors have examined lymphocytes of 26 patients suffering from schizophrenia of different types. The study has shown distinct disorders of DNA reparation associated with this disease, which is suggestive of deficiency or noncoordination of the enzymatic system explained by mutations in corresponding genes. Disorders of DNA reparation have until recently been known to be associated only with hereditary diseases.

Mechanisms of DNA repair in lymphocytes of persons having occupational contact with heavy metal salts for at least 10 years were investigated. The long-term exposure to heavy metal salts did not result in development of mechanisms of adaptation to the respective metals, as shown by increased DNA sensitivity to these compounds and by decrease in the repair activity. However, in some cases, resistance to other mutagens, 4-NQO, in particular, was observed.