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Biomedical subjects

M A Petrova

Publications and source records attributed to M A Petrova.

At least 19 recordsLinked to original sources
PubMed2006

[Origin, evolution, and migration of drug resistance genes].

Current views on the mechanisms responsible for the emergence of multiple drug resistance in clinical bacterial isolates are considered. Hypotheses on the origin of resistance genes derived from determinants of actinomycetes, antibiotic producers, and chromosomal genes of bacteria involved in cellular metabolism are reviewed. The mechanisms underlying the diffusion of resistance determinants by means of bacterial mobile elements (plasmids, transposons, and integrons) are discussed. Examples of the horizontal transfer of resistance determinants between Gram-positive and Gram-negative bacteria are presented.

Amino Acid Sequence↗
PubMed2004

[Distribution of transposons Tn5044 and Tn5070 with unusual mer operons in environmental bacterial populations].

The distribution of unusual mercury resistance transposons, Tn5044 and Tn5070, was examined. A characteristic feature of Tn5044 is temperature sensitivity of its mercury operon and the presence in the mer operon of the gene homologous to RNA polymerase a subunit. Structural organization of mercury operon Tn5070, containing minimum gene set (merRTPA), differs from mer operons of both Gram-negative and Gram-positive bacteria. None of more than two thousand environmental bacterial strains displaying mercury resistance and isolated from the samples selected from different geographical regions hybridized to Tn5040- and Tn5070-specific probes. A concept on the existence of cosmopolite, endemic, and rare transposons in environmental bacterial populations was formulated.

DNA Transposable Elements↗
PubMed2002

[Mercury-resistant bacteria from permafrost sediments and prospects for their use in comparative studies of mercury resistance determinants].

Mercury-resistant bacteria were isolated from permafrost sediments of Kolyma lowland and Canada existing over five thousand to two million years. Their content was shown to vary within the range 0.001-2.9% and to depend on the amount of mercury in sampling sites (coefficient of correlation 0.75). A collection of mercury-resistant bacterial strains was created. In this collection, various representatives of both Gram-positive bacteria (Bacillus, Exiguobacterium, Micrococcus, Arthrobacter) and Gram-negative bacteria (Pseudomonas, Acinetobacter, Plesiomonas, Myxobacteriales) were identified. Most resistant bacteria were found to contain determinants homologous to mer-operons of contemporary bacteria. The isolated strains of paleobacteria are proposed to be used for a comparative structural study of contemporary and ancient plasmids and transposons carrying mercury resistance determinants.

Bacteria↗
PubMed2001

Re-evaluation of osmotic effects as a general adaptative strategy for bacteria in sub-freezing conditions.

We studied the molecular mechanisms of adaptation of a Siberian psychrophilic bacterial strain. Upon adaptation to 4 degreesC from 24 degreesC, the major changes observed were in the membrane and cell surface chemistry. There was no evidence for the formation of so-called 'compatible metabolites' that are thought to be responsible for the survival at very low to sub-freezing temperatures. The membrane fatty acids were shorter with an increased amount of unsaturation in the 4 degreesC cells compared to the 24 degreesC cells. The absence of a significant amount of phosphorylation in the membrane lipids at 4 degreesC compared to the levels at 24 degreesC was another significant difference. At 4 degreesC, the cell size was reduced in volume by a factor of approximately 14 compared to its size at 24 degreesC. The polar polysaccharide capsular layer was also significantly reduced. There were no significant changes in the protein profiles indicating that antifreeze proteins were not being produced. The results obtained here are consistent with observations and established theories and principles on and about the behavior of water in confined spaces. These indicate that ordering effects, surface charge and polarity are the key determinants of the freezing point and the type of ice structure that will be formed when water is confined to an area of the size of a bacterial cell.

Adaptation, Physiological↗
PubMed2001

[Genetic factors in predisposition to bronchial asthma].

The ratio between the normal (+) and null (0) alleles of the genes encoding glutatione S-transferases M1 (GSTM1) and T1 (GSTT1) were studied in normal individuals from northwestern Russia (control group) and in patients with bronchial asthma (BA). The frequency of the GSTM1 0/0 genotype in the population sample was statistically significantly lower (37.8%) than in the BA patients (82.1%; chi 2 = 16.8; P < 0.001; w chi 2 = 15.7; alpha = 0.01). For the GSTT1 gene, similar data were obtained. The frequency of the GSTT1 0/0 genotype in healthy donors was statistically significantly higher (16.3%) than in the BA patients (73.7%; chi 2 = 28.5; P < 0.001; w chi 2 = 23.22; alpha = 0.01). A significant preponderance of the compound homozygotes for the GSTM1 and GSTT1 null alleles among the BA patients was observed. The frequency of the GSTM1 0/0, GSTT1 0/0 individuals among the patients was 57.9%, while it was only 4.7% among the controls (chi 2 = 27.4; P < 0.001).

Alleles↗
PubMed2000

[Role of biological defects in formation and development of bronchial asthma and potentialities of premorbid diagnosis].

The paper considers bronchial asthma as a polygenic disease. It presents some data available in the literature on the role of genetic disorders in the development of atopic states and the authors' own findings of various biological defects detected in apparently healthy blood relatives of patients with bronchial asthma. It is concluded that premorbid diagnosis is of importance in high risk persons.

Asthma↗
PubMed1998

Horizontal spread of mer operons among gram-positive bacteria in natural environments.

Horizontal dissemination of the genes responsible for resistance to toxic pollutants may play a key role in the adaptation of bacterial populations to environmental contaminants. However, the frequency and extent of gene dissemination in natural environments is not known. A natural horizontal spread of two distinct mercury resistance (mer) operon variants, which occurred amongst diverse Bacillus and related species over wide geographical areas, is reported. One mer variant encodes a mercuric reductase with a single N-terminal domain, whilst the other encodes a reductase with a duplicated N-terminal domain. The strains containing the former mer operon types are sensitive to organomercurials, and are most common in the terrestrial mercury-resistant Bacillus populations studied in this work. The strains containing the latter operon types are resistant to organomercurials, and dominate in a Minamata Bay mercury-resistant Bacillus population, previously described in the literature. At least three distinct transposons (related to a class II vancomycin-resistance transposon, Tn1546, from a clinical Enterococcus strain) and conjugative plasmids are implicated as mediators of the spread of these mer operons.

Bacillus↗
PubMed1996

[Clinical significance of specific features of HLA antigen incidence in patients with mucoviscidosis and in their relatives].

The distribution of antigens in the HLA system was studied in 57 patients with mucoviscidosis and in their 43 relatives. The examinees were found to have increased incidence of the HLA antigens B40, CW2, CW3, CW4. The haplotype AIB40 was associated with the mutation carriage of the CF gene deletion F508 both in patients and their relations heterozygous for this mutation. The analysis of the level of HLA antigens in the tissue of CF patients may predict the development of particular clinical features of mucoviscidosis and the nature of the course of the disease.

Adolescent↗
PubMed1995

[Bronchial nonspecific reactivity in patients with bronchial asthma and in the preasthmatic state and its alteration under the influence of acupuncture].

The development of nonspecific bronchial hypersensitivity and hyperreactivity in bronchial asthma and effectiveness of its correction with acupuncture were investigated in 152 patients with asthma and preasthma. 94 of them were subjected to acupuncture. The authors employed a complex of diagnostic methods with determination of 241 parameters processed later with the use of systemic modelling. Bronchial hypersensitivity as indicated by the response to acetylcholine was related to impaired coordination of bronchomotor tone regulating systems: parasympathetic part of the autonomic nervous system, eosinophilic and monocytic bronchial inflammation, glucocorticoid homeostatic alterations. The corrective role of acupuncture consists in reduction of nonspecific bronchial hyperreactivity, normalization of blood acetylcholine, resensitization of cell beta-adrenergic receptors, elevation of mean concentrations of 11-OCS and T-lymphocytes.

Acetylcholine↗
PubMed1995

[Disorders in mineral metabolism at different stages of the development of bronchial asthma].

Magnesium and calcium concentrations were measured by nuclear-absorption spectrometry (AAC-508, Hitachi, Japan) and selective ionometry (Microlyte, Kone, Finland) in the serum, red cells, lymphocytes, 24-h urine and exhaled air humor condensate in 23, 31 and 23 sibs (parents and their children) with preasthma, atopic bronchial asthma, free of these diseases, respectively. All the patients had magnesium deficiency and calcium hyperconcentrations in the blood cells, low urine excretion of magnesium. Parathormone and calcitonin serum concentrations underwent no changes. It is suggested that in contrast to changes of endobronchial homeostasis of bivalent cations, those of electrolyte cell composition are primary and appear prior to clinical manifestations of bronchial asthma.

Adolescent↗
PubMed1993

Cryoprotective properties of water in the Earth cryolithosphere and its role in exobiology.

In permanently frozen rocks, water occurs in all the three phases and plays a dual role from the biological point of view. About 93-98% of it is in the solid state. This, alongside with negative temperatures, contributes to cell cryoconservation. The remaining 2-7% is in the unfrozen state and represents thin films enveloping organic-mineral particles. These films play the role of cryoprotectors against cell damage by ice crystals during geologically significant time. Electron microscope examinations of prokaryotes revealed the well preserved outer cell structures, specifically strong envelopes and capsules. The cells are resistant to water phase transitions through 0 degrees C, i.e. to the freezing-thawing stress. The exobiological implication of this phenomenon is determined by the fact that the Earth permafrost at first approximation can he considered as a model of e.g. the Mars one. The latter protects the cells against radiation and simultaneously serves as a cryoconservant. However, most important is the possible presence of unfrozen (= liquid) water as prerequisite for the development of microbial life forms.

Cold Climate↗
PubMed1993

[Visual evoked potentials and functional asymmetry in children with with different degrees of intellectual retardation].

Visual evoked potentials (VEP) to flash and patterned visual stimuli have been recorded from occipital and central brain regions in 7-8-year-old boys with normal intellect (20 cases), with mental retardation (15 cases) and with oligophrenia of a debile degree (27 cases). A significant elongation of late-component latency has been revealed in motor brain areas VEP in oligophrenia group compared to normal subjects. A negative correlation between P190 component latency of motor area VEP to patterned visual stimulus and general and non-verbal intellectual indices has been stated in full right-handed subjects with intellectual deficiency. Such a relation was absent in right-handed patients with left dominant eye.

Child↗
PubMed1991

[The aldehyde dehydrogenase activity in the erythrocytes of alcoholic patients].

Red cell aldehyde dehydrogenase (ALDH, EC 1.2.1.3) activity was measured by spectrophotometry in normal subjects and alcoholics after various periods of alcohol abstinence. ALDH was measured in all red cell hemolysate fractions; red cells were purified from hemoglobin by Sephadex CM-50 chromatography. The enzyme activity was found reduced in alcoholics' red cells as against that in controls. ALDH activities were somewhat increasing and approaching the normal values in the patients not using ethanol for 4 weeks or longer. These results recommend ALDH measurements in human red cells as a test for the detection of subjects abusing alcohol.

Adult↗
PubMed1991

[The significance of immunogenetic body characteristics in the formation and development of bronchial asthma].

The antigenic composition of tissues was shown to be of importance in the formation of bronchial asthma on the basis of the clinicoimmunological data with regard to histocompatibility antigens in 235 patients suffering from bronchial asthma and preasthma. Well-defined correlations were established between the development of bronchial asthma with carriership of antigens A2, B13, B21 and B35, between the disease pattern and nature of its course and antigens B7, B12, B27, B35, B40 together with their combinations. Possible variants of the relationship between the body traits and certain mechanisms by which bronchial asthma develops are under discussion.

Aging↗
PubMed1990

[Diagnostic and prognostic significance of studying histocompatibility antigens in patients with bronchial asthma].

As a result of a comprehensive clinical and functional examination of 217 patients with bronchial asthma, including study of HLA-antigen composition of their tissues, a relationship between B13, B21 and B35 antigen carriers and susceptibility to bronchial asthma as well as associations with the form of the disease, its severity and some features of its course were found. Clinical examples confirming these arguments are illustrated. Possibilities of individual prognosis at a clinic are grounded.

Adolescent↗
PubMed1989

[The harmful action of ethanol on the liver: the role of alcohol dehydrogenase and aldehyde dehydrogenase].

White rats were divided into water-preferring (WP) and ethanol-preferring (EP) groups, on the basis of their preferable drink: either water or 15% solution of ethanol. Each of these groups was then subdivided into groups which were given to drink for 1 year 15% solution of ethanol (ethanol-treated) or water (controls). Alcohol dehydrogenase/aldehyde dehydrogenase activity ratios (ADH/AlDH) in livers of WP controls were considerably higher than those in EP controls. The difference in ADH/AlDH has somewhat decreased after ethanol treatment. However, this ratio remained the highest in the WP alcohol-treated group. The signs of proteinic and lipid dystrophy of the liver in alcohol-treated WP rats were expressed much more clearly than in all other groups. It is concluded that in the liver of animals with a high ADH/AlDH ratio there are favourable conditions for accumulation of a toxic hepatocyte-damaging acetaldehyde.

Alcohol Dehydrogenase↗