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Biomedical subjects

A Egorov

Publications and source records attributed to A Egorov.

17 recordsLinked to original sources
PubMed2006

Optimization of baculovirus transduction on FreeStyle293 cells for the generation of influenza B/Lee/40.

Recombinant baculovirus expression vectors derived from the Autographa californica nuclear polyhedrosis virus can serve as efficient gene-transfer vehicles for transient expression of recombinant proteins in a wide range of mammalian cell types and are able to produce multisubunit particles such as viruses or virus like particles. In this study, we constructed eight recombinant baculoviruses each containing one of the influenza B/Lee/40 virus genes in a bidirectional expression cassette for simultaneous mRNA and viral RNA transcription. Baculoviruses were transduced into FreeStyle293 in combination with the specific histone deacetylase inhibitor trichostatin A (TSA). Cotransduction conditions were optimized with a set of five baculoviruses (influenza B/Lee/40 PB1, PB2, PA, and NP and the control construct NCR-NS-minus-sense orientated encoding green fluorescent protein [rGFP]), which led to GFP expression in each host cell transduced with all five constructs. Based on the optimization with five constructs, transduction with eight baculoviruses was performed at MOI 50 and 100 with high yield stocks and 1 microM TSA and led to successful rescue of infectious influenza B/Lee/40 viruses.

Animals↗
PubMed2003

Effect of a single mutation in neuraminidase on the properties of Influenza B virus isolates.

Two strains of Influenza B virus were isolated in Vero cells. Subclones with improved efficiency of plaque formation were selected. The activity of the neuraminidase (NA) of the two subclones compared to their respective isolates dropped 20- and 100-fold, respectively. Both subclones had a common mutation in segment 6 leading to a change from Asp to Asn at position 457 in the NA. This mutation destroyed a salt bridge of the contact surface between the monomers, thereby causing the loss in enzymatic activity. The decreased NA activity caused improved plaque formation but had no significant impact on the replication in liquid culture.

Amino Acid Substitution↗
PubMed2001

Stability and formation of localized surface waves at the dielectric--photorefractive crystal boundary.

We consider specific features of the formation of localized surface waves at the interface between linear dielectric and photorefractive crystals with a nonlocal diffusion component of nonlinear response. Profiles of the surface waves are numerically found and guiding properties of the surface are investigated. Stability of the obtained surface waves is considered and it is shown that the well-known Vakhitov-Kolokolov stability criterion derived for the local Kerr or saturable material remains legible for the medium with a nonlocal diffusion component of nonlinear response.

Journal Article↗
PubMed2001

A genetically engineered fusion protein with horseradish peroxidase as a marker enzyme for use in competitive immunoassays.

Horseradish peroxidase is one of the most widely used marker enzymes in immunoassays. Several disadvantages are encountered upon chemical conjugation of peroxidase with antibodies or antigens, as are low reproducibility and undefined stoichiometry. We here describe for the first time the production of a recombinant fusion of a protein analyte with horseradish peroxidase in Escherichia coli, employing refolding of inclusion bodies and reconstitution with heme. The genetic fusion approach enables preparation of conjugates with 1:1 stoichiometry and defined structure. As a protein analyte, the human heart fatty acid binding protein (H-FABP) was chosen, which is a new and sensitive marker for acute myocardial infarction. The recombinant conjugate was fully active [650 U/mg with 2,2-azino-bis(3-ethyl-thiazoline-6-sulfonate) as substrate] and obtained in a yield of 12 mg/L of E. coli culture, which is better than that for recombinant peroxidase alone. The competitive immunoassay that was developed with the recombinant conjugate requires fewer incubation steps than the traditional sandwich ELISA format. It permitted the detection of H-FABP directly in plasma in the range of 10-1500 ng/mL which is the relevant range for clinical decision-making.

Biomarkers↗
PubMed2001

Hyperattenuated recombinant influenza A virus nonstructural-protein-encoding vectors induce human immunodeficiency virus type 1 Nef-specific systemic and mucosal immune responses in mice.

We have generated recombinant influenza A viruses belonging to the H1N1 and H3N2 virus subtypes containing an insertion of the 137 C-terminal amino acid residues of the human immunodeficiency virus type 1 (HIV-1) Nef protein into the influenza A virus nonstructural-protein (NS1) reading frame. These viral vectors were found to be genetically stable and capable of growing efficiently in embryonated chicken eggs and tissue culture cells but did not replicate in the murine respiratory tract. Despite the hyperattenuated phenotype of influenza/NS-Nef viruses, a Nef and influenza virus (nucleoprotein)-specific CD8(+)-T-cell response was detected in spleens and the lymph nodes draining the respiratory tract after a single intranasal immunization of mice. Compared to the primary response, a marked enhancement of the CD8(+)-T-cell response was detected in the systemic and mucosal compartments, including mouse urogenital tracts, if mice were primed with the H1N1 subtype vector and subsequently boosted with the H3N2 subtype vector. In addition, Nef-specific serum IgG was detected in mice which were immunized twice with the recombinant H1N1 and then boosted with the recombinant H3N2 subtype virus. These findings may contribute to the development of alternative immunization strategies utilizing hyperattenuated live recombinant influenza virus vectors to prevent or control infectious diseases, e.g., HIV-1 infection.

AIDS Vaccines↗
PubMed2000

Direct heterogeneous electron transfer of recombinant horseradish peroxidases on gold.

Clean polycrystalline gold electrodes were modified with native glycosylated horseradish peroxidases (HRP) or two different recombinant (carbohydrate free) HRPs; recombinant wild-type HRP (rec-HRP) and recombinant HRP containing a six histidine-tag at the C-terminus of the polypeptide chain (rec-HRP-His), respectively. Only the electrodes modified with the recombinant HRPs exhibited high current responses to H2O2 due to relatively rapid direct electron transfer (ET) between recombinant HRP and gold. The absence of a carbohydrate shell on rec-HRP and the additionally existing histidine-tag on rec-HRP-His improved the electrode sensitivity to H2O2 by more than 100 times if compared with the response observed at gold modified with native HRP. Rotating disk electrode experiments indicated that the heterogeneous electron transfer rates are equal to 4.7 and 7.5 s-1 for direct electron transfer between the gold electrode and rec-HRP or rec-HRP-His, respectively.

Electrochemistry↗
PubMed2000

Use of health information systems in the Russian federation in the assessment of environmental health effects.

The Russian Federation has made an intensive effort to compile and use information on the environment and human health. In 1996-1997, we evaluated the information that was collected and analyzed on the local (raion), regional (oblast), and federal levels with reference to its usefulness in the assessment of environmental health effects. The Russian Federation maintains standardized nationwide institutions that routinely collect health data in polyclinics and hospitals and then report to the national offices. The allocations of the workforce and the broad range of surveyed health outcomes are extensive, but a lack of systematic control of information quality limits the ability to take full advantage of these efforts. On the other hand, the hierarchical system of data collection has advantages over more decentralized or commercial health systems. A major weakness in the current reporting is the aggregation and transformation of data. Although this may not disturb the generation of health statistics, it seriously limits the use of regional and federal level data in the assessment of health effects of environmental exposures. In spite of limitations, some revised approaches to the analysis of existing data may be both feasible and fruitful. Combining information from routine data and newly collected data is likely to be the most effective way to assess the relationship between environmental exposures and diseases. Although there is a strong and justifiable desire to rapidly translate information of environmental health effects into policy alternatives, at present, it seems more useful to emphasize data quality, completeness, and plans for the use of data.

Data Collection↗
PubMed1998

Influenza A virus lacking the NS1 gene replicates in interferon-deficient systems.

The NS1 protein is the only nonstructural protein encoded by influenza A virus. It has been proposed that the NS1 performs several regulatory functions during the viral replication cycle, including the regulation of synthesis, transport, splicing, and translation of mRNAs. Through the use of reverse genetics, a viable transfectant influenza A virus (delNS1) which lacks the NS1 gene has been generated. Our results indicate that the NS1 of influenza A virus is an auxiliary (virulence) factor which plays a crucial role in inhibiting interferon-mediated antiviral responses of the host.

Animals↗
PubMed1998

Chimeric influenza virus replicating predominantly in the murine upper respiratory tract induces local immune responses against human immunodeficiency virus type 1 in the genital tract.

Previously, a mucosal model of immunization against human immunodeficiency virus type 1 (HIV-1) was established by using influenza virus as a vector for the neutralizing gp41 epitope ELDKWA. Whether replication of this chimeric influenza virus in the upper respiratory tract of mice is sufficient for inducing mucosal immune responses in the genital tract was investigated. An immunization strategy was established that permits the virus to replicate in the murine upper respiratory tracts but not in the lungs. Intranasal application of the chimeric virus induced HIV-1-specific antibodies in sera and genital tract. In addition, chimeric virus-specific antibody-secreting cells were detected in lymphocyte populations obtained from lungs, spleens, and urogenital tracts. These results indicate that replication of the chimeric influenza/ELDKWA virus in the upper respiratory tract is sufficient to induce systemic immune responses as well as local immune responses in the genital tract.

AIDS Vaccines↗
PubMed1998

Transfectant influenza A viruses with long deletions in the NS1 protein grow efficiently in Vero cells.

We established a reverse genetics system for the nonstructural (NS) gene segment of influenza A virus. This system is based on the use of the temperature-sensitive (ts) reassortant virus 25A-1. The 25A-1 virus contains the NS gene from influenza A/Leningrad/134/57 virus and the remaining gene segments from A/Puerto Rico (PR)/8/34 virus. This particular gene constellation was found to be responsible for the ts phenotype. For reverse genetics of the NS gene, a plasmid-derived NS gene from influenza A/PR/8/34 virus was ribonucleoprotein transfected into cells that were previously infected with the 25A-1 virus. Two subsequent passages of the transfection supernatant at 40 degreesC selected viruses containing the transfected NS gene derived from A/PR/8/34 virus. The high efficiency of the selection process permitted the rescue of transfectant viruses with large deletions of the C-terminal part of the NS1 protein. Viable transfectant viruses containing the N-terminal 124, 80, or 38 amino acids of the NS1 protein were obtained. Whereas all deletion mutants grew to high titers in Vero cells, growth on Madin-Darby canine kidney (MDCK) cells and replication in mice decreased with increasing length of the deletions. In Vero cells expression levels of viral proteins of the deletion mutants were similar to those of the wild type. In contrast, in MDCK cells the level of the M1 protein was significantly reduced for the deletion mutants.

Animals↗
PubMed1997

Effects of three days of dry immersion on heart rate and blood pressure variabilities during head-up tilting in humans.

In this study we examined the effects of 3 days of dry immersion on heart rate variability (HRV) and blood pressure variability (BPV) in response to head-up tilting in 4 healthy young subjects aged 21 to 36 years. Resting value of the high-frequency (HF) power of BPV and HRV decreased, while the low-frequency (LF)/HF ratio of HRV and blood pressure increased after the dry immersion. The HF power of HRV decreased, while the LF/HF ratio of HRV and heart rate increased during head-up tilting before and after dry immersion. All powers of BPV and BP were unchanged during head-up tilting. The values of the decrease in the HF power of HRV and the increase in the LF/HF ratio during head-up tilting after dry immersion were larger than those before. These results suggest that 3 days of dry immersion altered the autonomic balance toward the sympathetic dominant at rest, and that cardiac function may play a crucial role in BP maintenance during head-up tilting compared with vasoconstrictor function.

Adult↗
PubMed1988

Medical investigations results obtained in 125-day flight on "Salyut-7" and "Mir" orbital stations.

In 1986 in USSR medical investigations were continued in 125-day flight on "Salyut-7" and "Soyuz-T-15" orbital stations and on "Mir" basic block. Medical program consisted of medical control during active parts of flight and works in open space, profound medical examinations in rest and in function tests, metabolism and its regulation analysis, hygienic estimation of environment, estimation of prophylactic methods to prevent unfavourable influence of weightlessness on human organism. Cosmonauts felt well in all parts of flight on the dates of radio exchange, TV-seances, self- and each other control. Profound medical investigations discovered several individual changes in parametres of every cosmonaut's blood system. This charactaral changes appeared not in rest only, but with the influence of loading test and depended on initial hemodynamic status before the test.

Adaptation, Physiological↗
PubMedDate not supplied

Vaccine potential of influenza vectors expressing Mycobacterium tuberculosis ESAT-6 protein.

We generated several attenuated recombinant influenza A vectors expressing the Mycobacterium tuberculosis early secretory antigenic target (ESAT-6) protein. The ESAT-6 protein was recently identified as one of the most promising protective antigens for cell-mediated immunity. The obtained vectors appeared to be capable of inducing ESAT-6 specific Th1 immune response in mice after intranasal immunization. We found that double immunization with two influenza vectors of different subtypes provided a significant level of protection in mice, when applied as prophylactic vaccine, as well as substantial therapeutic effect in mice with pre-established tuberculosis infection. Moreover, we found a strong synergistic effect when vaccination with Flu/ESAT-6 vectors was combined with isoniazid treatment, resulting in a dramatic reduction of bacterial load in the lungs of infected mice.

Administration, Intranasal↗
PubMedDate not supplied

Using the PROGRESS transport spacecraft in structure of the International Space Station for realization of scientific experiments under microgravity conditions.

The problem is considered of using the PROGRESS transport spacecraft, which will deliver the payload on the ISS, as a free flying platform for realization of space experiments. For maintenance of the ISS 5-6 PROGRESS flights per year are planned. Usually after delivery of the payload the PROGRESS undocks from the ISS and burns down in the Earth atmosphere. However, the operating conditions of its onboard systems allow to prolong operation and to make free flight near to the station and repeatedly to be docked to it. It is offered to use this possibility for performing experiments on Material Science.

Acceleration↗
PubMedDate not supplied

Preliminary results of medical research on board the "Mir" orbital complex during its second main mission.

In 1987 the USSR orbital complex "Mir" accomplished its space mission, crewed by Yu.V. Romanenko (326 days), and A.I. Laveykin (about 176 days), who was replaced on the orbit (in consequence of some cardiac function peculiarities revealed in exercise conditions) by A.P. Aleksandrov (about 160 days). During the flight, extravehicular activity in the open space was carried out three times, and conjoint programmes were conducted, over a period of seven days, with an international Soviet-Syrian crew. The most important, fundamental result of the medical studies carried out in this flight seems to be the noted fact that Yu.V. Romanenko's 326 days in-flight (which means 3 months in excess to the results obtained hitherto) and his activity was not accompanied by developing any quantitatively new functional shifts, when compared to other long-term flights. Besides that, the cosmonaut maintained his functional endurance and work capacity on satisfactory levels. These results are in apparent relation with the rationally composed crew complement, the contribution the ground services responsible for the work-rest regimen and the whole life activity on board the station, as well as with the systematic and sufficiently extensive use of preventive measures. The general feeling and work capacity of the other crew members were also good throughout the flight. However, the reactions observed in each cosmonaut showed their individual characteristics, which are discussed in the paper.

Adult↗