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Biomedical subjects

V V Vlassov

Publications and source records attributed to V V Vlassov.

At least 19 recordsLinked to original sources
PubMed2006

Cell-free and cell-bound circulating DNA in breast tumours: DNA quantification and analysis of tumour-related gene methylation.

Tumour development is characterised by the increased circulating DNA (cirDNA) concentration and by tumour-related changes in blood plasma DNA. Concentration of cirDNA and methylation of RARbeta2, RASSF1A and HIC-1 gene promoters were investigated in cell-free and cell-surface-bound fractions from healthy donors, patients with breast cancer, and patients with breast fibroadenoma. Tumour development was shown to lead to significant changes in the distribution of cirDNA between cell-free and cell-surface-bound fractions. Analysis of RARbeta2 and RASSF1A methylation in the total cirDNA provides 95% diagnostic coverage in breast cancer patients, 60% in patients with benign lesions, and is without false-positive results in healthy women. Results of the study indicate that methylation-specific PCR of RARbeta2 and RASSF1A genes based on the total cirDNA combined with the quantitative analysis of cirDNA distribution between cell-bound and cell-free fractions in blood provide the sensitive and accurate detection and discrimination of malignant and benign breast tumours.

Breast Neoplasms↗
PubMed2006

Low level laser therapy for treating tuberculosis.

BACKGROUND: The main treatment for tuberculosis is antituberculous drugs. Low level laser therapy is used as an adjunct to antituberculous drugs, predominantly in the former Soviet Union and India. OBJECTIVES: To compare low level laser therapy plus antituberculous drugs with antituberculous drugs alone for treating tuberculosis. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group Specialized Register (December 2005), CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), EMBASE (1974 to December 2005), CINAHL (1982 to December 2005), Science Citation Index (1945 to December 2005), PEDro (1929 to December 2005), the Central Medical Library of Moscow catalogue (1988 to June 2005), the internet, and reference lists of articles. We contacted relevant organizations and researchers for the original version. SELECTION CRITERIA: Randomized trials comparing low level laser therapy plus antituberculous drugs with antituberculous drugs alone in people with tuberculosis. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data, including adverse events. MAIN RESULTS: One randomized controlled trial (130 participants) conducted in India met the inclusion criteria. This trial was poorly reported, with no information on the generation of allocation sequence or allocation concealment. The trial report did not provide details on the group that each of the participants were randomized into or which group those participants that left the trial were from. This precluded the use of its data on time to sputum conversion and other outcome measures for analysis. AUTHORS' CONCLUSIONS: The use of low level laser therapy for treating tuberculosis is still not supported by reliable evidence. Researchers need to focus on conducting well-designed randomized controlled trials to justify the continued participation of volunteers for studies of this experimental intervention.

Humans↗
PubMed2005

Perfluoroarylazide derivatives of 2'-O-modified oligoribonucleotides: efficient reagents for RNA photomodification.

Site-specific photomodification of the 5'-terminal fragment of MDR1 mRNA by perfluoroarylazide derivatives of 2'-O-modified (2'-O-methyl or 2'-O-tetrahydropyranyl) oligoribo- and oligodeoxyribonucleotides was investigated. The conjugates built of 2'-O-modified oligoribonucleotides demonstrate beneficial features compared with their deoxyribo analogs: the extent of RNA modification by 2'-O-modified oligoribonucleotides and oligodeoxyribonucleotide conjugates was 40- 50% and 20%, respectively.

Azides↗
PubMed2004

Expression of the MDR1 and MRP genes in patients with lymphoma with primary bone marrow involvement.

Expression of MDR1 and MRP genes in patients with low-grade and high-grade non-Hodgkin's lymphomas with primary bone marrow involvement before and after chemotherapy was investigated. The data demonstrate that overexpression of MDR1 and MRP genes in hematological malignancies elevates in patients after chemotherapy and correlates with poor clinic prognosis and more frequent recurrences of the malignancies.

Antineoplastic Agents↗
PubMed2004

Oxidative DNA cleavage by free and oligonucleotide-conjugated O-bromobenzoic acid in the presence of copper(II) ions.

o-Bromobenzoic acid was found to promote copper-dependent reactive oxygen species formation from molecular oxygen, resulting in DNA base modification and backbone cleavage. The oligonucleotide conjugate bearing 5-(4'-aminopropyl-sulfomoyl)-2-bromobenzoic acid as a reactive group was synthesized and DNA cleavage activity of this oligonucleotide conjugate was tested on a model deoxyoligonucleotide.

Base Sequence↗
PubMed2004

Silencing of MDR 1 gene in cancer cells by siRNA.

Inhibition of p-glycoprotein (PGP) expression and reverse of multidrug resistance (MDR) phenotype in KB-8-5 cells by synthetic 21-bp double-stranded oligoribonucleotides were investigated. siRNA constructs for the efficient down regulation of MDR1 that are active in nanomolar concentrations and cause reversal of MDR phenotype in cells were developed.

Base Sequence↗
PubMed2004

Silencing of c-myc expression in tumor cells by siRNA.

Suppression of c-myc protooncogene expression in KB-3-1 cells by siRNA was investigated. The siRNA duplex targeted to the exon 3 of c-myc mRNA was prepared by in vitro transcription with T7 RNA polymerase on short dsDNA-templates. It was found that incubation of KB-3-1 cells in the presence of 75 nM siRNA results in decrease of the c-myc mRNA level down to 5% of the level in the control cells and significant decline of KB-3-1 cell proliferation rate. Using 200 nM siRNA four-fold decrease of KB-3-1 cells proliferation rate was observed and this effect was stable at least 96 h after transfection.

Base Sequence↗
PubMed2004

Ribonuclease activity of the peptides with alternating arginine and leucine residues conjugated to tetrathymidilate.

RNA cleaving conjugates have been prepared by attachment of oligodeoxyribonucleotide TTTT to peptides containing arginine, leucine, proline and serine residues. The highest activity was displayed by the conjugates containing peptides with alternating arginine and leucine residues (LR)4G-amide. Ribonuclease activity of the conjugates pep-T4 decreases in the order T4-(LR)4G > T4-(LR)2G > T4-(LLRR)2G > T4-(LR)2PRLRG > S2R3-Hmda-T4 > or = R5 double dagger (LR)3. According to CD spectra, the free peptide (LR)4G-amide in water solution at neutral pH and physiological ionic strength has no pronounced secondary structure whereas conjugated to oligonucleotide it acquires a folding similar to alpha-helix.

Arginine↗
PubMed2003

Interaction of keratin K1 with nucleic acids on the cell surface.

The interaction of surface proteins from A431 cells and cellular extracts with nucleic acids was investigated using affinity modification with 32P-labeled reactive oligonucleotide derivatives. Proteins with molecular weights of 68, 46, 38, and 28 kD as well as several low molecular weight proteins capable of binding to nucleic acids were found on the surface of intact cells. It was demonstrated that a protein with molecular weight of 68 kD is exposed at the cell surface, since the treatment of cells with trypsin results in the cleavage of this protein. Disruption of the integrity of the cell membrane (scrapping, treatment with trypsin, or permeabilization of the cell membrane with streptolysin O or saponin) disrupts the interaction of the reactive oligonucleotides with the cell surface proteins. Affinity modification of the cytosolic and membrane-cytosolic cell fractions with labeled oligonucleotides results in the modification of a large number of proteins, where proteins with molecular weights of 68, 46, 38, and 28 kD can be found as minor components. Surface oligonucleotide-binding proteins with molecular weight of ~68 kD were isolated by affinity chromatography after the modification of intact A431 cells with a reactive oligonucleotide derivative. The isolated surface oligonucleotide-binding proteins from A431 cells were sequenced, and one of the proteins was identified as keratin K1.

Animals↗
PubMed2002

Low level laser therapy for treating tuberculosis.

BACKGROUND: The main treatment for tuberculosis is antituberculous drugs. Low energy laser therapy is used as an adjunct to antituberculous drugs, predominantly in the former Soviet Union and India. OBJECTIVES: To assess the benefits and harms of low level laser therapy for treating tuberculosis in randomized and quasi-randomized controlled trials. To seek information about potential benefits or harms from observational studies. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group specialized trials register (up to June 2001), the Cochrane Controlled Trials Register (Issue 1, 2001), MEDLINE (1966 to December 2001), EMBASE (1988 to December 2001), CINAHL (up to November 2001), PEDro (up to November 2001), the Science Citation Index (up to December 2001), National Centre for Science Information at the Indian Institute of Science (15 April 2002), electronic catalogue of the Central Medical Library (Moscow; 1988 to January 2002), the internet using 'Google' (21 January 2002), and reference lists of articles. We contacted relevant organizations and researchers. SELECTION CRITERIA: (1) Randomized and quasi-randomized controlled trials comparing low level laser therapy with no low level laser therapy in people with tuberculosis. We also conducted a subsidiary analysis of of the potential benefits and harms from observational studies. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. We contacted study authors for additional information. Adverse event information was collected from the studies. MAIN RESULTS: No randomized or quasi-randomized controlled trials met the inclusion criteria for the review. The potential benefits and harms from 29 observational studies involving over 3500 people are described. REVIEWER'S CONCLUSIONS: We have not identified any well designed trials using low level laser therapy (LLLT) to treat tuberculosis. Therefore, the use of LLLT to treat tuberculosis is not supported by reliable evidence.

Humans↗
PubMed2002

Cationic lipid-DNA complexes-lipoplexes-for gene transfer and therapy.

Cationic lipid-mediated gene transfer and delivery still attract great attention of many gene therapy laboratories. From the point of view of the most important characteristics of lipoplex particles, e.g. its charge and size, we reviewed recent studies available. In general, the paper deals with non-viral systems of gene transfer into eukaryotic cell based on various lipids. Having usually less efficiency in gene transfer, lipid-based gene transfer vehicles (lipoplexes/genosomes) are characterized with certain advantages even over viral ones: they are less toxic and immunogenic, could be targetable and are easy for large-scale production, a size of transferred DNA being quite high. Conditions of DNA condensation during interactions with lipids are described. Results of the studies of mechanism of DNA-lipid complex interactions with the cell membrane and their transport into the nucleus are summarized. Dependence of efficiency of gene transfer on lipoplex structure and physical-chemical properties is reviewed. Advantages and disadvantages of different macromolecule complexes from the point of view of transfection efficiency, possibility of use in vivo, cytotoxicity and targeted gene transfer in certain organs and tissues are also discussed. Results of transfection of different cells using neutral, anion and cation liposomes are reviewed. The conclusion reached was that efficiency and specificity of gene transfer may grow considerably when mixed macromolecule lipid systems including polycations and glycolipids are used.

Animals↗
PubMed2000

Secondary structure of the 5'-region of PGY1/MDR1 mRNA.

In order to identify the optimal target sites for antisense oligonucleotides in the human multiple drug resistance mRNA, the secondary structure of the 5'-terminal part of this mRNA (nucleotides 1-678) was investigated. By using results of probing with ribonucleases T1, ONE and V1 and results of computer simulations, a model of the 5'-region of the PGY1/MDR1 mRNA was built. The molecule is formed by three major domains comprising several hairpins separated by single-stranded fragments. The predicted single-stranded regions of the PGY1/MDR1 mRNA efficiently bind complementary oligonucleotides.

5' Untranslated Regions↗
PubMed1999

Characterisation of membrane oligonucleotide-binding proteins and oligonucleotide uptake in keratinocytes.

Inadequate cellular compartmentalisation of plasmid DNA and antisense oligodeoxynucleotides (ODNs) is generally considered as a major limitation in their use. In this study, an approach combining in situ visual-isation of rhodamine-labelled ODNs and affinity modification of proteins by radiolabelled-alkylating ODN derivatives has been used to investigate the uptake of ODNs into keratinocytes. We confirm here that unmodified ODNs are efficiently taken up and accumulate in cell nuclei in primary keratinocytes as well as in HaCaT and A431 keratinocyte cell lines. Uptake is fast, irreversible, saturable and not significantly altered by incubation at low temperature. Affinity modification studies in keratinocyte cell lines has revealed two high-affinity, cell-specific interactions between ODNs and proteins of 61-63 kDa and 35 kDa. Trypsin pre-treatment of A431 cells and pre-incubation with polyanions, or with unlabelled nucleic acid competitors, inhibited the accumulation of rhodamine-labelled ODNs in nuclei as well as the affinity labelling of the 61-63 kDa doublet and 35 kDa ODN-binding proteins by reactive ODN derivatives. Finally, cell fractionation studies indicated that these ODN-binding proteins were essentially localised in the plasma membrane. Our results suggest that these ODN-binding proteins might be involved in the recognition and transport of ODNs into keratinocytes.

Cells, Cultured↗
PubMed1999

Activation of spleen lymphocytes by plasmid DNA.

Plasmid pUC19 DNA was shown to stimulate in vitro proliferation of CBA mouse splenocytes in a dose-dependent manner. Simultaneous treatment of the cells with the plasmid DNA and Con A or LPS produced an additive effect, while PMA acted synergistically with DNA. Monovalent Fab fragments of rabbit anti-mouse Ig (RAMIg) antibodies significantly inhibited plasmid DNA-induced polyclonal lymphocyte activation suggesting the involvement of Ig receptors in this process. Affinity modification of lymphocytes membrane-cytosole proteins with a 32P-labeled alkylating oligonucleotide derivative resulted in labeling of 67-82 and 23 kDa polypeptides corresponding to IgD and IgM heavy and light chains respectively. The immunoglobulin nature of the 82 and 23 kDa oligonucleotide-binding polypeptides was confirmed by immunoprecipitation with RAMIg antibodies.

Animals↗
PubMed1999

Hybridization of antisense oligonucleotides with the 3'part of tRNA(Phe).

The interaction of antisense oligodeoxyribonucleotides with yeast tRNA(Phe) was investigated. 14-15-mers complementary to the 3'-terminal sequence including the ACCA end bind to the tRNA under physiological conditions. At low oligonucleotide concentrations the binding occurs at the unique complementary site. At higher oligonucleotide concentrations, the second oligonucleotide molecule binds to the complex due to non-perfect duplex formation in the T-loop stabilized by stacking between the two bound oligonucleotides. In these complexes the acceptor stem is open and the 5'-terminal sequence of the tRNA is accessible for binding of a complementary oligonucleotide. The results prove that the efficient binding of oligonucleotides to the 3'-terminal sequence of the tRNA occurs through initial binding to the single-stranded sequence ACCA followed by invasion in the acceptor stem and strand displacement.

Base Sequence↗
PubMed1999

Refined high-field NMR solution structure of a binary-addressed pyrene/perfluoro-azide complementary DNA oligonucleotide system shows extensive distortion in the central nick region.

The structural analysis of the photoactivated binary system of complementary-addressing nucleic acid sequences (1:2:3) by high-resolution NMR spectroscopy and restrained molecular dynamics is reported. The binary system comprised a 12 base-pair target DNA sequence, pdGTATCAGTTTCT (1), and two hexanucleotides, (dAGAAACp-L-Az (2) and Pyr-pdTGATAC (3)), complementary to neighbouring sites in the target DNA. Oligonucleotide (2) is conjugated with a p-azidotetrafludrobenzyl group (Az) via a linker group (L), and the other oligonucleotide (3) is equipped with the photosensitizing pyrenyl-1-methylamino group (Pyr). We now extend the structural analysis of 1:2:3, which was previously based on qualitative 2D 1H-NMR data and thermodynamic analysis of complex formation from UV-visible thermal denaturation experiments. In the current work structural refinement was performed by separate molecular dynamics runs for six different starting structures based on 318 proton-proton distance-range constraints, evaluated from the 1H-NOESY spectrum (tau(mix) = 200 ms, 600 MHz) using complete relaxation matrix analysis (NMR/TRIAD/MARDIGRAS). Additional Watson-Crick hydrogen bond restraints were included in the calculations based on the detected signals from the exchangeable protons, using REFOPT(NY) methods. The final averaged structure obtained from the six refined co-ordinate sets showed a considerable degree of axis bend (62.5 degrees) with the bending point in the middle of the duplex in the region of the backbone nick between the two short oligonucleotides. The complex behaves dynamically as the equivalent of two short B-DNA-like duplexes displaying a hinge-like flexing at their junction. In all final structures the Pyr function location was very restricted, the aromatic group lying in the duplex minor groove near residues 4T, 5C and 2T. In contrast, the location of the perfluoroazido group was different in all the final structures, indicating the high flexibility of this group in the duplex. The only feature common to all six final azido group orientations was the outside location on the side of the major groove. The distance between the Pyr and Az groups varied from 11 A to 24 A for the six final structures (17 A, final average structure). The dynamics of duplex denaturation for 1:2:3 was probed by monitoring the temperature-induced NMR line broadening of the imino protons in a 1D variable temperature NMR experiment. The melting of 1:2:3 starts both from the ends and from the middle part of the duplex at the backbone break between the two short oligonucleotides reflecting the destabilisation of the pyrene-arylazido nick region in the duplex.

Azides↗