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Biomedical subjects

V V Vlassov

Publications and source records attributed to V V Vlassov.

At least 55 records · Page 3Linked to original sources
PubMed1994

Serum immunoglobulins interact with oligonucleotides.

The interaction of reactive derivatives of oligonucleotides bearing a 4-[(N-2-chloroethyl-N-methyl)amino]benzylamin residue at the 5'-terminal phosphate with serum blood proteins has been investigated. It was found that the compounds react with serum albumin and immunoglobulins M and G, the reactivity increasing in the order: albumin < IgG < IgM. The reactions with immunoglobulins were inhibited in the presence of different oligonucleotides, DNA and heparin, suggesting the oligonucleotide binding to some cationic region of the proteins. Myoglobin inhibited the interaction of oligonucleotide derivatives with myoglobin-specific monoclonal antibodies which indicates that the derivatives interact with the proteins within or near the antigen binding site.

Antibodies, Monoclonal↗
PubMed1994

Ethidium and azidoethidium oligonucleotide derivatives: synthesis, complementary complex formation and sequence-specific photomodification of the single-stranded and double-stranded target oligo- and polynucleotides.

Oligodeoxyribonucleotide derivatives containing ethidium or azidoethidium residues attached to 3' and/or 5' end were prepared. These derivatives formed tight specific complexes with complementary oligodeoxyribonucleotides where each attached ethidium residue led to an increase of complex Tm by 20-30 degrees C. Tandem complexes of two oligodeoxyribonucleotides containing ethidium residues with an oligodeoxyribonucleotide having two adjacent complementary sequences for these oligonucleotides were investigated. Photoinduced reactions of a number of ethidium and azidoethidium oligodeoxyribonucleotide derivatives with target complementary single-stranded and double-stranded oligo- and polydeoxyribonucleotides were investigated. The irradiation led to direct photocleavage of the target oligo- or polynucleotide, to formation of hidden (piperidine cleavable) modifications of the target and to formation of covalent adducts between ethidium oligodeoxyribonucleotide derivative and the target. In a number of experiments, azidoethidium dyes were demonstrated to be considerably stronger photosensitizers than ethidium ones. Depending on the nature of the target (single- or double-stranded DNA) and on the irradiation conditions, the total damages to the target oligo- or polydeoxyribonucleotides ranged from 10-70% (for ethidium dyes) to 30-80% (for azidoethidium dyes).

Azides↗
PubMed1994

Oligo(A), oligo(TG), and Alu repeats of DNA in chromatin are available for sequence-specific chemical modification with oligodeoxynucleotide derivatives.

Reaction of 4-(N-2-chloroethyl-N-methylamino) benzylphosphamides of oligonucleotides, which are targeted to the poly(A), poly(TG), and Alu repeats of eukaryotic DNA in chromatin and isolated nuclei from HeLa cells, has been investigated. It was found that the reagents alkylate DNA and some proteins due to specific complex formation. The affinity character of the reaction was proved by the fact that free corresponding oligonucleotides taken in excess or preliminary treatment of chromatin with S1 nuclease both prevent the biopolymers from the modification. Deproteinated DNA from the same cells does not react with oligonucleotide derivatives. This suggests that the chromatin DNA must have some structural features allowing oligonucleotide binding. Reactivity may be attributed to the existence of strongly negative supercoiled DNA regions containing single-stranded sequences or regions where DNA can unwind in the presence of complementary oligonucleotides. Results obtained suggest that in eukaryotic chromatin there are open DNA sequences available for affinity modification with oligonucleotide derivatives not only due to formation of triple helixes.

Adenine Nucleotides↗
PubMed1994

Iontophoretic delivery of oligonucleotide derivatives into mouse tumor.

Oligodeoxyribonucleotides (22-mers) were delivered through the skin of C3H mice in the region of a mammary gland tumor by means of iontophoresis. It was shown that the oligonucleotides enter the tumor, cross it, and reach all mouse organs. Electrophoretic analysis of the oligonucleotide extracted from tumor showed that the compounds were delivered in the tissue in the intact state.

Administration, Topical↗
PubMed1993

Synthetic RNA-cleaving molecules mimicking ribonuclease A active center. Design and cleavage of tRNA transcripts.

RNA cleaving molecules were synthesized by conjugating imidazole residues imitating the essential imidazoles in the active center of pancreatic ribonuclease to an intercalating compound, derivative of phenazine capable of binding to the double stranded regions of polynucleotides. Action of the molecules on tRNA was investigated. It was found, that some of the compounds bearing two imidazole residues cleave tRNA under physiological conditions. The cleavage reaction shows a bell-shaped pH dependence with a maximum at pH 7.0 indicating participation of protonated and non-protonated imidazole residues in the process. Under the conditions stabilizing the tRNA structure, a tRNAAsp transcript was cleaved preferentially at the junctions of the stem and loop regions of the cloverleaf tRNA fold, at the five positions C56, C43, C20.1, U13, and U8, with a marked preference for C56. This cleavage pattern is consistent with a hydrolysis mechanism involving non-covalent binding of the compounds to the double-stranded regions of tRNA followed by an attack of the imidazole residues at the juxtaposed flexible single-stranded regions of the molecule. The compounds provide new probes for the investigation of RNA structure in solution and potential reactive groups for antisense oligonucleotide derivatives.

Base Sequence↗
PubMed1993

Penetration of oligonucleotides into mouse organism through mucosa and skin.

Benzylamide 5'-32P-oligonucleotide derivatives were shown to penetrate into mice organism when administered by various routes; intranasally, per os, intravaginally and per rectum. In all cases, the compounds are rapidly accumulated in blood and guts. Analysis of the radioactive material from blood and pancreas revealed intact oligonucleotides. Although concentrations of oligonucleotides in tissues differ considerably by the various methods of administration, the efficiency of delivery is sufficient to consider all the routes as being of therapeutic value. Dose effect on the efficiency of oligonucleotide penetration into mice suggests the transport to be a saturable process. Application of an oligonucleotide lotion on mice ear helices results in reproducible accumulation of radioactivity in the animal tissues. Effectiveness of oligonucleotide delivery into mouse through skin can be improved by using electrophoretic procedure.

Animals↗
PubMed1993

c-fos gene expression in cell revertants from a transformed to a pseudonormal phenotype.

c-fos gene expression in two types of mouse sarcoma cells of spontaneous origin and in revertants to pseudonormal phenotype has been investigated. In the latter cells the content of c-fos mRNA is similar to that in normal fibroblasts. Activity of transcription factors interacting with the regulatory elements, SRE, DSE and TRE, in the c-fos promoter do not correlate with the c-fos mRNA concentration. However, experiments with cells transformed with the indicator plasmid, fos-CAT, showed that the 600 bp c-fos promoter region provides the chloramphenicol acetyltransferase activity correlating with c-fos mRNA expression in cell revertants to a pseudonormal phenotype.

Animals↗
PubMed1993

Inhibition of HIV proliferation in MT-4 cells by antisense oligonucleotide conjugated to lipophilic groups.

Anti-HIV activity of antisense oligonucleotide derivatives conjugated to lipophilic groups has been investigated. Aliphatic linear structures and cholesterol were coupled to the 5'-terminal phosphate of oligonucleotides via glycine or propylene diamine spacers. The oligonucleotides were targeted to a conserved sequence of the viral gene env, to a sequence in the negative sense viral RNA, to the 5'-terminus of the gene rev and to poly(A) sequences. The conjugation with lipophilic groups stimulated binding of oligonucleotides to cells and protected the oligonucleotides against cellular nucleases. The lipophilic derivatives of oligonucleotides containing an ester bond in the linker structure were cleaved by cellular esterases yielding oligonucleotides protected from 5'-nuclease degradation by the glycine residue. Antiviral activity of the derivatives exceeded that of the corresponding unmodified oligonucleotides. The virus suppression was sequence-specific and most pronounced in the case of the cholesteryl conjugated oligonucleotides.

Base Sequence↗
PubMed1993

Specificity of interaction of pyrimidine oligonucleotides with DNA at acidic pH in the presence of magnesium ions: affinity modification study.

Sequence-specific alkylation of dsDNA with pyrimidine oligonucleotides bearing an alkylating group at the 3' and 5' terminal phosphates, or both, has been investigated. At pH 5.4, sequence-specific modification of guanosines of the DNA in the vicinity of the target purine-pyrimidine sequence occurs. The reactive group at the 5' terminus of the oligonucleotides attacks guanosines in the purine strand of the target DNA. The reactive group at the 3' end can interact with guanosines in both strands of the DNA. Bifunctional reagents can alkylate both strands of the DNA simultaneously. At pH 4 in the presence of magnesium ions, the oligonucleotide derivatives can form imperfect complexes with sequences homologous to the target sequence and alkylate the DNA at the corresponding positions.

Alkylation↗
PubMed1992

Affinity modification of human chromatin with reactive derivatives of oligonucleotides.

Reaction of 4-(N-2-chloroethyl-N-methylamino)benzylphosphamides of oligonucleotides (RCl-(pT)16 and RCl-(pApC)6) with human chromatin in intact nuclei and with metaphase chromosomes has been investigated. The oligonucleotides were targeted to poly(A) and poly(TG)-repeating DNA sequences. It was found that the reagents alkylate DNA and some proteins due to specific complex formation. The affinity character of the reaction was proved by the fact that free corresponding oligonucleotides taken in excess or preliminary treatment of chromatin with S1-nuclease both prevent the biopolymers from modification. The results obtained evidence that in human chromatin there are open DNA sequences available for affinity modification with oligonucleotide derivatives. Analysis of patterns of modified proteins within these chromatin areas may give a key to the structure of these chromatin sites.

Benzene Derivatives↗
PubMed1992

Interaction of cholesterol-conjugated alkylating oligonucleotide derivatives with cellular biopolymers.

Interactions of oligonucleotide derivatives with mammalian cells and cellular biopolymers have been investigated. The derivatives were oligonucleotides bearing an alkylating 2-chloroethylamino group at the 3'-end and a cholesterol residue at the 5'-terminal phosphate. These compounds are readily taken up by cells and react with cellular DNA, RNA and some proteins which may play a role in delivery of the compounds into cells.

Alkylation↗
PubMed1992

Cell membranes as barriers for antisense constructions.

The results of studies on interaction of oligonucleotides and polynucleotides with cell membranes are reviewed. Oligonucleotides and polynucleotides bind to lipid membranes in the presence of divalent cations that may result in spontaneous encapsulation of nucleic acids and transfer of the formed vesicles to the other side of the membrane. Oligonucleotides can enter eukaryotic cells and interact with cellular RNA and DNA. On the surface of eukaryotic cells, there are proteins capable of binding to nucleic acids that may be involved in oligonucleotide uptake. Oligonucleotides bind to cellular CD4 receptors. Efficient delivery into cells can be achieved by conjugation of oligonucleotides to lipophilic groups or by encapsulation into membrane carriers.

Animals↗
PubMed1992

Sequence-specific cleavage of single-stranded DNA by oligonucleotides conjugated to bleomycin.

Cleavage of a single-stranded DNA fragment by complementary oligonucleotides conjugated to bleomycin A5 has been investigated. The conjugates efficiently cleave the DNA at the GT sequences near the oligonucleotide binding site. The temperature dependence of the reaction and the composition of the degradation products indicate that the oligonucleotide-linked bleomycin attacks the available double-stranded DNA regions within the oligonucleotide-DNA duplex and in the hairpin DNA region in the vicinity of the carrier oligonucleotide binding site.

Antibiotics, Antineoplastic↗
PubMed1991

Reactive oligonucleotide derivatives as gene-targeted biologically active compounds and affinity probes.

Development of efficient methods for synthesis of oligonucleotides and oligonucleotide analogs has opened up the possibility of designing a broad spectrum of affinity reagents for specific modification of nucleic acids and proteins. These affinity reagents are used for investigation of the topology of ribosomes and nucleic acid polymerases. Oligonucleotides and their analogs are already used for suppression of specific gene expression and for elucidation of the physiological role of their products. Oligonucleotide derivatives appear to offer considerable promise as potential gene-targeted drugs such as antivirals and specific inhibitors of oncogene expression.

Affinity Labels↗
PubMed1991

Sequence-specific alkylation of dsDNA with derivatives of pyrimidine oligonucleotides conjugated to 2-chloroethylamine groups.

Reaction of homopyrimidine oligonucleotides bearing a 5'-terminal alkylating aromatic 2-chloroethyl-amino group with a bovine papilloma vector expressing human interferon-gamma was investigated. The oligonucleotide derivatives bound to corresponding homopurine-homopyrimidine sequences in dsDNA and alkylated guanosine residues at these sites in the purine strand of the target. The alkylated DNA can be cleaved at the modified residues. At pH 5.4, the reaction was highly specific to the target sequences; at pH less than 5, some nonspecific reactions were observed at the sequences partially complementary to the oligonucleotides. Elongation of the linker between the alkylating group and the oligonucleotide phosphate increased the alkylation efficiency. Repeated treatment of the DNA with gradually increased concentrations of the reagent resulted in quantitative modification of the target guanosines.

Alkylation↗