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Biomedical subjects

A A Volkov

Publications and source records attributed to A A Volkov.

At least 19 recordsLinked to original sources
PubMed2006

[Comparative study of the population structure and population assignment of sockeye salmon Oncorhynchus nerka from West Kamchatka based on RAPD-PCR and microsatellite polymorphism].

Using two types of molecular markers, a comparative analysis of the population structure of sockeye salmon from West Kamchatka as well as population assignment of each individual fish were carried out. The values of a RAPD-PCR-based population assignment test (94-100%) were somewhat higher than those based on microsatellite data (74-84%). However, these results seem quite satisfactory because of high polymorphism of the microsatellite loci examined. The UPGMA dendrograms of genetic similarity of three largest spawning populations, constructed using each of the methods, were highly reliable, which was demonstrated by high bootstrap indices (100% in the case of RAPD-PCR; 84 and 100%, in the case of microsatellite analysis), though the resultant trees differed from one another. The different topology of the trees, in our view, is explained by the fact that the employed methods explored different parts of the genome; hence, the obtained results, albeit valid, may not correlate. Thus, to enhance reliability of the results, several methods of analysis should be used concurrently.

Alleles↗
PubMed2006

[Long-term results of bronchial resection and plastic repair in patients with lung cancer].

Thoracic units perform plastic operations on the bronchi in 5-10% of all radical interventions for lung cancer. This figure was 7.5% at our unit. A total of 184 patients were operated on, with a mortality rate of 9.7% (18 patients died). Lobectomy with circulatory resection of the main bronchus is the optimal plastic operation on the bronchi in lung cancer. Long-term results following bronchial resection and plastic repair suggest the oncological rationale for these operations. These operations make it possible to preserve functionally significant lung tissue, thus assuring the high quality of life in the patient.

Adult↗
PubMed2002

[Surgical treatment of bronchial asthma].

Methods of surgical treatment of bronchial asthma (BA) are classified as first generation (glomectomy, gangliectomy, vagotomy, pulmonary roots denervation), second generation (implantation of neurostimulators of sinocarotid, diaphragmal nerves, vagus, sympathic trunks), third generation (implants of programmed microchips). 7-year experience of surgical treatment with second generation methods in 125 patients with BA and experience of third generation methods use are summarized. Methods of second and third generations are most promising, permit to prevent and to cure asphyxia attack without drugs--with electrostimulation of vegetative system structures by impulse current (30-150 Hz, 0.01-0.1 ms, 0.5-2.0 V). New methods increase remission period more than 2 times, reduce drug daily requirement not less than 2 times. New methods can be used with traditional drug therapy and don't lead to dangerous for life complications. From first generation methods of BA's surgical treatment, only glomectomy and pulmonary roots denervation can be performed on serious demand.

Adult↗
PubMed1999

Formation of indigo by recombinant mammalian cytochrome P450.

The development of bicistronic systems for coexpression of recombinant human cytochrome P450 enzymes (P450s) with their redox partner, NADPH-cytochrome P450 reductase (NPR), has enabled P450 activity to be reconstituted within bacterial cells. During expression of recombinant P450 2E1 and some other forms, we observed the formation of a blue pigment in bacterial cultures. The pigment was extracted from cultures and shown to comigrate with standard indigo on TLC. UV-visible spectroscopy and mass spectrometric analysis provided further support for identification of the pigment as indigo. Indigo is known to form following the spontaneous oxidation of 3-hydroxyindole. Accordingly, we speculated that indole, formed as a breakdown product of tryptophan in bacteria, was hydroxylated by the P450 system, leading to indigo formation. Bacterial membranes containing recombinant P450 2E1 and human NPR were incubated in vitro with indole and shown to catalyze formation of a blue pigment in a time- and cofactor-dependent manner. These studies suggest potential applications of mammalian P450 enzymes in industrial indigo production or in the development of novel colorimetric assays based on indole hydroxylation.

Cytochrome P-450 CYP2E1↗
PubMed1999

Recombination and chimeragenesis by in vitro heteroduplex formation and in vivo repair.

We describe a simple method for creating libraries of chimeric DNA sequences derived from homologous parental sequences. A heteroduplex formed in vitro is used to transform bacterial cells where repair of regions of non-identity in the heteroduplex creates a library of new, recombined sequences composed of elements from each parent. Heteroduplex recombination provides a convenient addition to existing DNA recombination methods ('DNA shuffling') and should be particularly useful for recombining large genes or entire operons. This method can be used to create libraries of chimeric polynucleotides and proteins for directed evolution to improve their properties or to study structure-function relationships. We also describe a simple test system for evaluating the performance of DNA recombination methods in which recombination of genes encoding truncated green fluorescent protein (GFP) reconstructs the full-length gene and restores its characteristic fluorescence. Comprising seven truncated GFP constructs, this system can be used to evaluate the efficiency of recombination between mismatches separated by as few as 24 bp and as many as 463 bp. The optimized heteroduplex recombination protocol is quite efficient, generating nearly 30% fluorescent colonies for recombination between two genes containing stop codons 463 bp apart (compared to a theoretical limit of 50%).

Cloning, Molecular↗
PubMed1999

Directed evolution of biocatalysts.

Directed evolution is being used increasingly in academic and industrial laboratories to modify and improve important biocatalysts. Significant advances during this period of review include compartmentalization of genes and the in vitro translation apparatus in emulsions, as well as several impressive demonstrations of catalyst improvement. Shuffling of homologous genes offers a new way to utilize natural diversity in the evolution of novel catalysts.

Catalysis↗
PubMed1990

[Results of psychometric and questionnaire methods in the evaluation of noise and vibration on floating oil rigs in the Caspian sea].

A psychometric study of noise and vibration was performed at different parts of the Caspian floating oil rigs. The analysis of 500 questionnaires received from the personnel showed that the correlation coefficients for different values, depending on the parameters of the levels, were 0.71-0.87 for noise and 0.33-0.44 for vibration. The noise levels calculated for oil workers of different professions, were: in cabins, recreation rooms and working sites 40-52, 57-63 and 73-74 dBA respectively, and the comparative vibration rate levels were 67-74, 79-85 and 90-97 dB, respectively. 273 questionnaires revealed that the acoustic conditions in the abins affected both the process of falling asleep and depth of sleep (correlation coefficients 0.88 and 0.93, respectively). Noise levels at 30-36 dBA did not cause any sleep discomfort. 84% questionnaires contained in average 3.5 complaints, with the maximum 5.2 complaints for the machine operators, and the minimum 3.2 complaints for the electricians who worked in acoustically more favorable conditions. The study proved that the psychometric and questionnaire data in 70% cases corresponded to the results of the laboratory techniques, such as audiometry, chronoreflexometry, tono- and pulsometry, electrocardiometry, etc. The research data received served a basis for noise and vibration hygienic norming in floating oil-rig sites.

Humans↗
PubMed1989

[Hepatic scintigraphy using 123I-rose bengal].

The paper is devoted to the experience in diagnostic investigations using rose bengal, labeled with half-life 123I (123I-RB). The drug was synthesized in the B. P. Konstantinov Leningrad Institute of Nuclear Physics, USSR Academy of Sciences. Analysis of the results of investigations of 201 patients with diseases of the liver and biliary tracts revealed the advantages of 123I-RB over standard RPs of similar diagnostic purpose. Owing to low radiation exposure one could use higher activity (up to 120 MBq and more) of the drug. It made it possible to combine a study of the functional parameters of the hepatobiliary system and obtaining scintigraphic data on the structure of the liver and biliary tracts. 123I-RB is the best radiodiagnostic agent for a study of function and topography of the liver in patients with an increased blood level of bilirubin.

Adult↗
PubMed1988

Electron microscopy study of Q beta replicase.

Purified preparations of Q beta replicase have been studied by electron microscopy using a negative staining technique, and a three-dimensional model of the enzyme molecule has been constructed. The molecule of this four-subunit protein appears to be a compact structure having a size of 100 +/- 10 A; it is subdivided into two unequal bipartite subparticles. The conclusion has been made that all the constituent subunits, including the ribosomal protein Sl, acquire a globular conformation when associated in the replicase complex.

Coliphages↗
PubMed1988

[Activities of the Department of Radiation Diagnosis of the Central Scientific Research Roentgenoradiology Institute].

The main stages in the activities of the scientific units of the Institute since its foundation up to now were represented. The role of Prof. M.I. Nemenov, the founder of the Institute, as a scientist and organizer, and investigations of the staff-members, conducted in different periods, were described. The essence of some researches, carried out at the Institute, was briefly reported.

Academies and Institutes↗
PubMed1988

[Scintigraphic evaluation of the results of treatment of alcoholic liver cirrhosis].

The results of static and dynamic scintigraphy in patients with alcoholic liver cirrhosis showed changes in liver sizes, a decrease in the RL/LL ratio, an increase in spleen sizes, the reduction or distortion of the L/S ratio, extrahepatic uptake of RP, and predominance of the arterial component of the blood flow over the portal one. However the main scintigraphic signs of alcoholic liver cirrhosis were undetectable. After therapy (lymphovenous anastomosis, embolization of the hepatic artery) the recovery of functions was more rapid in patients with cirrhosis of alcoholic etiology who discontinued alcohol consumption than in those with cirrhosis of some other etiology.

Embolization, Therapeutic↗