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Biomedical subjects

S A Grachev

Publications and source records attributed to S A Grachev.

At least 19 recordsLinked to original sources
PubMed2005

[The influence of nitric oxide inductor (NaNO2) on the sensitivity of Chinese hamster cells to hyperthermia].

Formerly we reported the reduction of sensitivity to gamma- and UV-radiation in Chinese hamster cells of line 90 under the influence of nitric oxide inductor (NaNO2). Of interest was to learn if it possible to reduce the influence of hyperthermia on cells by means of NO inductor. A 1 h long incubation with this NO donor demonstrated an increased survival of cells heated up to 45 degrees C, and a decreased frequency of chromosomal aberrations in these. Employment of cycloheximide (CHE), an inhibitor of protein synthesis, and administration of CHE together with nitric oxide donor (NaNO2), equally increased the cell survival at hyperthermia. These and relevant literature data suggest that the demonstrated effect of exogenous NO may be associated with HSP70 protein. The noticed decrease in the number of chromosomal aberrations in heated cells under the influence of NO donor may play an important role in its modifying effect on cells at hyperthermia.

Animals↗
PubMed2004

[Effect of nitric oxide donor (NaNO2) on the stability of non-transformed and malignant cells to ultraviolet and gamma-radiation].

A decreased sensitivity of the Chinese hamster cells (line V-79) to gamma-radiation under the influence of nitric oxide induction was shown elsewhere. This effect is connected hypothetically with post-radiation reparation of DNA. The investigation of the nitric oxide donor effect on sensitivity of these to UV-radiation is of interest, because this radiation is an important ecological factor of the environment. The question of retention of nitric oxide positive effect on UV and gamma-radiation sensitivity in malignant HeLa cells is no less actual, because these cells significantly differ from normal cells of line V-79. We demonstrated that the donor of nitric oxide enhances stability of the Chinese hamster cells (line V-79) to UV-radiation, as well as to gamma-radiation independently of the time of cell incubation with sodium oxide donor before or after irradiation. The inefficiency of nitric oxide as a factor increasing UV-stability of cells was shown for malignant HeLa cells. A 1 h long incubation of these cells with NO-donor before gamma-irradiation decreased the number of chromosome aberrations, and conversely, the addition of this agent to the HeLa cell culture after gamma-irradiation did not change the radiostability. It may be inferred that distinctions in behaviour of nitric oxide in cultures of V-79 and HeLa cells using UV-radiation may be explained by transformation of the latter special features of their damage, and by the following reparation.

Animals↗
PubMed2001

[Thoracoabscessotomy in combined treatment of lung gangrene].

Patients with gangrene and gangrenous abscess of the lung belong to the most severe group of patients with purulent lung diseases. Conservative treatment is not effective, lethality after lung resection or pneumonectomy ranges from 20 to 70%, therefore the study of less traumatic but life-saving operations is topical. From 1996 to 1998, 296 patients with purulent destructive processes in the lung were hospitalized, 34 of them had gangrene or gangrenous abscess of the lung with significant intoxication. Thoracoabscessostomy by original method with consecutive necrectomies, sanitation of purulent cavity was performed in 27 patients. After operation 2 patients died, 25 patients were discharged with clinical recovery in satisfactory conditions, with dry cavity in the lung. In remote terms the cavities are cicatrized or transform to spurious cysts. Indications for thoracoabscessostomy are formulated. It is method of choice in the treatment of patients with gangrenous lung abscess, when conservative treatment is not effective, but the risk of radical operation is very high.

Gangrene↗
PubMed1995

Formation of 5-hydroxy-5,6-dihydrouracil and release of undamaged uracil as a result of poly(U) irradiation in N2O-saturated aqueous solution.

The radiation chemical yields of 5-hydroxy-5,6-dihydrouracil and uracil were measured on radiolysis of N2O-saturated solutions containing I mmol dm-3 poly(U) and were found to be 0.04 and 0.31 mumol J-1 respectively. From the 5-hydroxy-5,6-dihydrouracil yield in the presence of cysteamine and 2-mercaptoethanol, it is shown that only 20% of the OH-radicals, which attack poly(U) results in the formation of 5-hydroxy uracil adducts. It has been proposed that as yet unknown reducing radicals are formed in addition to known reducing radicals (the 5-OH-adducts of uracil, the H-adducts of uracil, and sugar radicals) as a result of the reaction of OH-radicals with poly(U).

Hydroxyl Radical↗
PubMed1991

In vitro membrane binding of the translation products of the carlavirus 7-kDa protein genes.

Two double-stranded DNA copies of the genes potentially coding for the 7-kDa proteins of potato virus M (PVM) and potato virus S (PVS) were synthesized and cloned into T7 transcription vectors. Cell-free translation of the corresponding monocistronic transcripts yielded in both cases a single protein of approximately 7-8 kDa that contains a highly hydrophobic N-terminal segment. To analyze their membrane-binding potential, both proteins were synthesized in the membrane-enriched Krebs-2 extract. It was found that the smooth membrane fraction was enriched in the carlavirus 7-kDa proteins. The primary and predicted secondary structures of their N-terminal hydrophobic segments suggest that the latter can function as signals for translocation into the rough endoplasmic reticulum.

Amino Acid Sequence↗
PubMed1989

[Inclusion of biotinylated analogs of dUTP and dCTP in DNA by DNA-polymerases. Cloning DNA fragments, containing biotinylated deoxyribouridine in E. coli].

The synthesis of a biotinylated derivative of dCTP, viz. N4-[(N-biotinyl)-4-amino-butoxyl]-2'-deoxycytidine 5'-triphosphate (I), is described. DNA polymerase I (Klenow fragment) incorporates (I) in DNA chains instead of thymidine, although with a lower efficiency than previously described biotinylated dUTP derivative (II), whereas highly purified DNA polymerase alpha from human placenta uses as substrate derivative (II) but not (I). A DNA fragment bearing biotin residues in one of strands was synthesized with the use of DNA polymerase alpha and dUTP derivative (II); its cloning in the plasmid vector pBR322 revealed that the DNA nucleotide sequence remained intact.

Base Sequence↗
PubMed1988

A highly basic histone H4 domain bound to the sharply bent region of nucleosomal DNA.

A nucleosomal core particle is composed of two each of histones H2A, H2B, H3 and H4 located inside the particle with approximately 47 base pairs (bp) of DNA wrapped around the octamer in about 1.8 turns of a left-handed superhelix. The path of the superhelix is not smooth; the DNA is sharply bent, or kinked, at positions symmetrically disposed at a distance of about one and four double-helical turns in both directions from the nucleosomal dyad axis (designated as sites +/- 1 and +/- 4 respectively). This non-uniform bending is considered archetypal to other DNA-protein complexes, but its mechanism is not clear (reviewed in ref. 4). DNA-histone chemical cross-linking within the core particle has revealed strong binding of each of the two histone H4 molecules to DNA at a distance of 1.5 helical turns either side of the nucleosomal dyad axis (sites +/- 1.5). In each of these sites, a single flexible domain of H4 was previously shown to contact three points, at about nucleotides 55 and 65 on one strand and nucleotide 88 on the complementary strand, numbering from the 5' terminus of each 147-base strand; these three locations are closely juxtaposed across the highly compressed minor and major grooves (Fig. 1). Here we report that the amino-acid residue of histone H4 cross-linked at the 1.5 site is histidine-18, embedded in a highly basic cluster Lys-Arg-His-Arg-Lys-Val-Leu-Arg which is probably involved in the sharp bending of the DNA double helix at the +/- 1 sites.

Amino Acid Sequence↗
PubMed1988

Identification of sequence-specific DNA-binding factors by label transfer: application to the adenovirus-2 major late promoter.

A method of affinity labelling proteins specifically associated with DNA target sequences is proposed. The method utilizes covalent UV-crosslinking of proteins to highly labelled DNA (e.g. in crude cell or nuclear extracts) followed by degradation of the DNA to short oligonucleotides. Proteins selectively labelled by attached residual oligonucleotides are readily amenable to molecular mass determination. Using this approach, we have characterized a HeLa polypeptide specifically bound to a short segment of the adenovirus-2 major late promoter (Ad2 MLP). A molecular mass value (approximately 51 kD) and precise location of the crosslinking site(s) of the protein within the MLP (-55 with respect to the cap site) were determined.

Adenoviruses, Human↗
PubMed1987

[Construction of DNA-probes and their immunochemical detection using nonradioactive hybridization tests].

Simple and efficient chemical approaches to preparation of DNA probes carrying 2,4-dinitrophenyl, dansyl or biotin residues were developed. The residues were introduced using following DNA derivatization procedures: a) transamination of cytidine residues with O-(4-aminobutyl)hydroxylamine; b) mercuration of pyrimidine residues followed by beta-mercaptoethanol modification. It was shown that 2,4-dinitrophenyl-containing DNA probes can be used for nonradioactive hybridization detection of nucleic acids. DNP-DNA: DNA complexes were detected using mouse antibodies specific to 2,4-dinitrophenyl groups, which were developed with peroxidase-conjugated antimouse immunoglobulins. Peroxidase-catalyzed chemoluminescent reaction of luminol oxidation with hydrogen peroxide allowed to detect 10 picograms of the dinitrophenylated single-stranded DNA probe.

Biotin↗
PubMed1985

Sequence-specific chemical modification of a 365-nucleotide-long DNA fragment with an alkylating oligonucleotide derivative.

An aromatic 2-chloroethylamino group was attached to the 5'-terminal phosphate of the oligodeoxyribonucleotide pCCCTCTTTCTT. The oligonucleotide derivative prepared was used for modification of the 365-nucleotide-long DNA fragment. It was found that modification of the fragment proceeds in a sequence-specific way at 3 guanosine residues within the sequence complementary to the oligonucleotide reagent.

Alkylation↗
PubMed1983

[The nucleotide sequence of the 3'-terminal region of encephalomyocarditis virus RNA].

Reverse transcription afforded DNA-copies of the 3'-terminal sequence of mouse encephalomyocarditis virus RNA. Cloning of this cDNA in pBR 322 plasmid and sequencing of DNA of one of the clones established the structure (552 nucleotide residues) of the 3'-terminus of viral RNA. This region contains a non-translatable fragment (126 nucleotides) and also the fragment coding for the C-terminus of viral replicase.

Animals↗
PubMedDate not supplied

[Increased efficacy of radiation protection against fission neutrons using unithiol].

It was found that the combination of unithiol (Sodium salt of 2,3-dimercapto-1-propansulfonic acid) with cystamine and AET diminished their toxicity. The optimum ratio for the antitoxic effect is 0.5 molar equivalent of unithiol per radioprotective 1.0 equivalent of thiol. Animals withstand big doses of protectors well, that gives an opportunity to use increased amounts of cystamine and AET. In the experiments with circular irradiation of male (CBA x C57B1)F1 mice weighing 18-22 g with fission neutrons (the neutron mean energy was 0.85 MeV, the contribution of gamma-quanta to the total was 25%, dose rate was 14 cGy/min) it was shown that the combination of unithiol with cystamine and AET enhances their radioprotective effect: the DRF of cystamine (150 mg/kg)--1.1, and the DRF of the combination of cystamine (300 mg/kg) with unithiol (152 mg/kg)--1.2; the DRF of AET (150 mg/kg)--1.2, the DRF of the combination of AET (300 mg/kg) with unithiol--1.4. Thus, the enhancement of dose of the radioprotectors, which was made possible as a result of their combination with unithiol, leads to enhancement of efficacy of chemical protection against fission neutron irradiation as much as 10-20%. Efficacy of AET is found to be comparable to efficacy of this protector in conditions of X-rays irradiation.

Animals↗
PubMedDate not supplied

[Effect of unithiol on cystamine toxicity in dogs].

In experiments with dogs it was shown that administration of unithiol before administration of cystamine decreases toxic effect of the last: period of excitation induced by cystamine is shortened, the time of emetic reaction decreases and expression of the emetic reaction to this preparation is diminished, the recorded EKG changes of conditions of heart decrease.

Animals↗