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Biomedical subjects

A I Shevchenko

Publications and source records attributed to A I Shevchenko.

At least 19 recordsLinked to original sources
PubMed2006

[Chromatin modifications during X-chromosome inactivation in female mammals].

In female mammals, the process of dosage compensation occurs during early embryonic development. As a result of this, one of X-chromosomes becomes transcriptionally inactive. This process is accompanied by chromatin remodeling on inactivated X-chromosome, providing transcriptional silencing of the genes and maintenance of their inactive state. In the present review, the dynamics of modifications occurring during embryonic inactivation, their distribution over the inactive X-chromosome, interaction, and the role in establishing and maintening the inactive state are discussed. As an illustration, modifications on the inactive X-chromosome of the Microtus common vole are presented.

Animals↗
PubMed2004

[Characterization and comparative analysis of DNA from the pericentric heterochromatin of chromosome 2 of Anopheles atroparvus V. Tiel (Culicidae, Diptera)].

The minilibrary containing DNA sequences from the diffuse pericentric heterochromatin from the right arm of Anopheles atroparvus V. Tiel (Culicidae, Diptera) chromosome 2 (2R) was generated by use of chromosome microdissection technique. Southern-blot hybridization of the minilibrary fragments with the labeled genomic DNA of A. atroparvus and analysis of their primary structure showed that this heterochromatin region contained repeated DNA sequences differed by their primary structure and the number of copies. These were mostly AT-rich sequences harboring the features characteristic of the S/MAR regions. Based on the clones homology to the sequences from the An. gambiae and Drosophila melanogaster genomes, it was demonstrated that the pericentric heterochromatin from the right arm of An. atroparvus chromosome 2 contained gypsy-like transposable elements, as well as the sequences homologous to the structural genes. In situ hybridization with the chromosomes of A. atroparvus and of the two representatives of the Anopheles maculipennis species complex, A. messeae and A. beklemishevi, showed that pericentric regions of all these chromosomes contained DNA sequences homologous to the sequences from the region-specific minilibrary. Cloned fragments of conserved repetitive DNA revealed upon interspecific Southern-blot hybridization of the clones with the labeled genomic DNA of A. messeae can be utilized in further investigations of evolutionary rearrangements of the pericentric heterochromatin within the Anopheles maculipennis species complex.

AT Rich Sequence↗
PubMed2003

[Intratumoral chemotherapy in the treatment of regional widespread pulmonary cancer].

A new method of treatment of pulmonary cancer using the introduction of cytostatic drugs and prednisolone into the tumor during bronchofibroscopy was suggested. This increases the effectiveness of treatment and reduces the side effects of drugs. Complete regression of tumor was observed in 9 (32.1%) patients of the main group, partial regression--in 12 (42.9%). In control group the regression was observed in 6 (20%) and in 10 (33.3%) patients, respectively.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

Reorganization of the X chromosome in voles of the genus Microtus.

Comparative chromosomal analysis is a powerful tool in the investigation of the mechanisms of chromosomal evolution. The accuracy of the analysis depends on the availability of region-specific markers to follow the fate of the particular chromosomal region through the evolution of species. We have assigned 12 unique sequences to the euchromatic part of the vole X chromosome, which serve as reliable markers of chromosomal segments. Together with region-specific libraries and GTG banding, these markers allow us to delineate the homologous regions of the X chromosomes in five species of the genus Microtus. We found that X chromosomes of these species differ by numerous rearrangements and all rearrangements are clustered at specific breakpoints. Moreover, these breakpoints were found to colocalise with repetitive and/or duplicated DNA sequences. We suggest that clusters of repeated and/or duplicated DNA sequences have played a crucial role in the formation of rearrangement hot spots during evolution of the X chromosome in the subgenus Microtus.

Animals↗
PubMed2001

Characterization of the genomic Xist locus in rodents reveals conservation of overall gene structure and tandem repeats but rapid evolution of unique sequence.

The Xist locus plays a central role in the regulation of X chromosome inactivation in mammals, although its exact mode of action remains to be elucidated. Evolutionary studies are important in identifying conserved genomic regions and defining their possible function. Here we report cloning, sequence analysis, and detailed characterization of the Xist gene from four closely related species of common vole (field mouse), Microtus arvalis. Our analysis reveals that there is overall conservation of Xist gene structure both between different vole species and relative to mouse and human Xist/XIST. Within transcribed sequence, there is significant conservation over five short regions of unique sequence and also over Xist-specific tandem repeats. The majority of unique sequences, however, are evolving at an unexpectedly high rate. This is also evident from analysis of flanking sequences, which reveals a very high rate of rearrangement and invasion of dispersed repeats. We discuss these results in the context of Xist gene function and evolution.

3' Untranslated Regions↗
PubMed2001

[Effect of pyracetam on fatigue of inspiratory muscles in cats].

The aim of the work was to study the influence of pyracetam on respiratory muscles fatigue and ventilatory disorders caused by inspiratory resistive load in cats. The experiments have show that after the use of pyracetam in conditions of fatigue total bioelectric activities of inspiratory muscles and of the phrenic nerve and transdiaphragmal pressure restore; duty cycle, respiratory rate and tidal volume per minute decrease. The conclusion is drawn that pyracetam in the dose 300 mg/kg, in intravenous administration, compensates inspiratory muscle fatigue at the expense of its central mechanism of action.

Animals↗
PubMed2001

[Inversion polymorphism and the divergence of two cryptic forms of Anopheles messeae (Diptera, Culicidae) at the level of genomic DNA repeats].

Genomic DNA of samples from several populations of malaria mosquito Anopheles messeae belonging to the macullipennis Paleoarctic complex was examined using digestion with ten restriction enzymes and electrophoresis in polyacrylamide gel. The patterns of DNA repeat fraction in the EcoRII hydrolysate in two cryptic forms of An. messeae characterized by common inversion polymorphism were shown to be different. The genomic differences in mixed sympatric groups and those between geographically remote populations of the different forms were identical. No interindividual, intrafamilial, inter- and intrapopulation variation was revealed in either form. The electrophoregrams of individuals belonging to the same the B form but having different combinations of inversion chromosomal variants in the karyotypes were identical. Analysis of taxonprints in the forms showed that individuals with the same karyotype may belong to different forms. These results coupled with evidence on the ecological features of and assortative mating in An. messeae populations demonstrated that the examined forms are not conspecific. Our results indicate that taxonprint analysis is the most reliable and precise test for the presence of conspecific forms in a large sympatric zone.

Animals↗
PubMed2000

[The correction of the immune status at the postoperative rehabilitative stage in lung cancer patients by using millimeter-wave resonance therapy].

Results are submitted of study into effects of microwave resonance therapy (MRT) on parameters characterizing cell immunity in those lung cancer patients having undergone a radical operation. This study comprised 58 patients as the main group, with 31 patients being controls. Indices for cell immunity were also studied in 20 donors. There was a rise in T-lymphocytes after MRT in the postoperative period. MRT contributed to prolongation of patients' lives, reduction of the incidence of chemotherapy-related dyspeptic complications and that of leukopenia cases by 8 and 9 percent respectively.

Adenocarcinoma↗
PubMed1999

[Optimization of indications for performance of surgical interventions in patients with lung cancer using the game theory].

The possibility of the mathematical theory of plays application for the choice of an optimal tactics in radical treatment of pulmonary cancer was studied. After the late follow-up result studying of the 506 patients treatment the expected life span was mathematically calculated depending on stage and histological structure of tumour. Similar indexes were calculated for patients, which were not operated on. The theory of plays application had promoted the postoperative mortality lowering from 5.4 to 3.2% and of postoperative complications rate from 12.5 to 9.3%.

Adenocarcinoma↗
PubMed1998

[Reconstructive-plastic operations as one of the measures for the medical rehabilitation of lung cancer patients].

The follow-up result of reconstructive-plastic operations in 68 patients with pulmonary cancer are studied. Preoperative irradiation therapy (20 Gr the summary dose), using middle fractions, was conducted in 21 patients. While doing the operation, pleura was worked by polymethylsiloxane-400 in 32 patients for the postoperative adhesive pleuritis prophylaxis. The patients survival index after reconstructive-plastic operations did not differ from such in a control group.

Adult↗