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Biomedical subjects

Iu A Nikolaev

Publications and source records attributed to Iu A Nikolaev.

At least 19 recordsLinked to original sources
PubMed2001

[Complex evaluation of the impact of emerging mining industries in Northern regions on public health].

The studies covered public health state in vicinity of concentration enterprise being built in Far North, with selecting a cohort of workers extracting diamonds in Yakutia, conducting a primary standardized health screening in accordance with WHO program. The public health state is characterized in connection with ecologic, social and economic circumstances. The authors necessitate complex evaluation of influence caused by industrial enterprises on health of workers and general population.

Catchment Area, Health↗
PubMed1993

[An evaluation of the course and prognosis of hypertrophic cardiomyopathy in relation to the presence of circulatory failure].

A total of 55 patients with hypertropic cardiomyopathy (HCMP) with and without circulatory insufficiency were examined at rest and in the restorative period (up to 24 hours) after graded exercise. The serum levels of lactate were measured and the activity of lysosomal enzymes: acid phosphatase, beta-glucosidase and beta-galactosidase were assayed. Healthy untrained donors (n = 21) and athletes (n = 12) with moderately working myocardial hypertrophy, as evidenced by echocardiography served as controls. The patients with HCMP had higher lactate levels and enhanced activity of lysosomal enzymes both at rest and during exercise than the controls. Highest hyperenzymia was found in HCMP patients with circulatory insufficiency and in those without the latter who showed progressive disease even with signs of circulatory insufficiency during 6-9 month follow-ups. In these groups, the patients had the lowest capacity to restore after exercise. It is concluded that the high activity of blood lysosomal enzymes in HCMP patients is a poor predictor.

Adolescent↗
PubMed1991

[The cytochemical determination of lysosomal cationic proteins in the blood neutrophils in hypertrophic cardiomyopathy].

Examinations of 33 patients with hypertrophic cardiomyopathy have revealed Stages I-II circulation insufficiency in 15. The findings were compared with those in 20 untrained normal subjects and 8 athletes. Lysosomal cationic protein levels were measured in polymorphonuclear leukocytes by the cytochemical method at rest, at the peak of dosed exercise (permanently increasing bicycle spiroergometry) and over the course of the recovery period--in 3, 12, and 24 h after exercise. The neutrophil distribution was also estimated by the staining intensity. Lysosomal cationic protein levels in hypertrophic cardiomyopathy patients with and without circulation insufficiency were changed to a different degree; these characteristics essentially varied in the patients, normal untrained subjects, and athletes. Changed levels of lysosomal cationic proteins appear to reflect the microcirculation disorders and the augmenting hypoxemia in the patients with circulation insufficiency, and thus may be used as a criterion to assess the clinical course of hypertrophic cardiomyopathy.

Adult↗
PubMedDate not supplied

[Cross-action of extracellular stress adaptation factors in microorganisms].

The capacity of microorganisms from different taxa to adapt to stress conditions with the help of extracellular factors exhibiting similar mechanisms of action was demonstrated. The action of adaptation factors synthesized by the enteric bacterium Escherichia coli, the soil bacterium Bacillus subtilis, and the yeast Candida utilis was characterized in biological tests. It was demonstrated that the factor of accelerated adaptation to new media (FAANM) and the growth-rate-reducing factor (factor X(II)), which decreases the rate of exponential culture growth, were synthesized by all microorganisms tested. Antilysin (factor X(I)), which accelerates cell adaptation to N-ethylmaleimide, was not produced by C. utilis.

Adaptation, Biological↗
PubMedDate not supplied

[Extracellular factors affecting the adhesion of Pseudomonas fluorescens cells to glass surface].

Two factors affecting the adhesion of Pseudomonas fluorescens to glass surfaces were revealed in the culture liquid (CL) of this bacterium. One of these factors, adhesin, which is responsible for cell adhesion, was found to be a protein substance located both at the cell surface and in the CL. Bacterial cells grown in rich LB medium were less adhesive than cells grown in minimal M9 medium. The adhesive capacity of cells was independent of the growth phase. The other factor, anti-adhesion (AA), which reduces cell adhesion, was found only in the CL. AA concentration in the CL increased with the culture age.

Adhesins, Bacterial↗
PubMedDate not supplied

[Properties of adhesin and antiadhesin from Pseudomonas fluorescence].

Some properties of the adhesion-modifying factors of Pseudomonas fluorescens are described. Adhesin, which promotes the adhesion of P. fluorescens cells, is a hydrophobic compound of a protein nature with a molecular mass of more than 10 kDa located either at the cell surface or in the medium. Anti-adhesion, which suppresses the adhesion of P. fluorescens cells, is a thermolabile hydrophobic compound of a nonprotein nature with a molecular mass of less than 3 kDa. Heating makes anti-adhesin hydrophilic. The role of adhesion and anti-adhesion in the adhesion and adaptation of P. fluorescens cells is discussed.

Adhesins, Bacterial↗
PubMedDate not supplied

[Regulation of the adhesion of Pseudomonas fluorescens cells to glass by culture-produced volatile compounds].

The effect of the gaseous metabolites of one Pseudomonas fluorescens culture on the attachment of cells of another Pseudomonas fluorescens culture to glass was studied. Gaseous metabolites increased the number of unattached cells by 10-30% and the mean residence time of cells attached to glass by 100%. These effects were presumably due to the yet unidentified compound, which we called volatile antiadhesin. This compound could be adsorbed by activated carbon and HAYESEP-Q adsorbent.

Air↗
PubMedDate not supplied

[Role of distant cellular communications in regulation of Pseudomonas fluorescens adhesion].

The effects of long-range interactions (LRI) and culture air on the adhesion of Pseudomonas fluorescens cells were studied. One P. fluorescens culture was found to diminish the adhesion of cells of another, glass-screened, P. fluorescens culture by 30%. This effect was interpreted to be due to penetrating LRI. Under the combined action of LRI and culture air (the latter alone reduced cell adhesion by only several percent), the amount of unattached cells increased 2- to 30-fold (on the average, by a factor of nine). Such a great reduction of cell adhesion indicated the synergistic action of LRI and culture air.

Bacterial Adhesion↗
PubMedDate not supplied

[Distant informational interactions in bacteria].

Exchange of information between bacteria via physical signals, referred to as "distant interactions" (DI), is the subject of this review. All cases of DI reported to date are discussed, as well as the history of these studies and the place of DI in bacterial communication. Bacterial DI are a particular case of DI occurring in nature (in plants, animals, and fungi). Along with the chemical signals of intracellular communications, DI play a significant role in the life of microorganisms, especially during critical periods.

Bacteria↗
PubMedDate not supplied

[Extracellular factors of adaptation of Pneudomonas fluorescens batch cultures to adverse conditions].

The culture liquid filtrate of an exponential-phase Pseudomonas fluorescens batch culture added to another P. fluorescens culture at the moment of inoculation was found (1) to prevent or diminish cell adsorption of the flask walls; (2) to enhance the intensity of cell respiration; (3) to shorten the period of adaptation of LB-grown cells to growth in glucose-containing mineral M9 medium; (4) to stimulate bacterial growth at supraoptimum temperature (36 degrees C) and pH values (4.8 and 9.2); and (5) to decrease the death rate of bacteria at the supraoptimum growth temperature. These results were interpreted as indicating that P. fluorescens cultures produce two types of regulatory exometabolites similar to those revealed earlier in Escherichia coli and Bacillus subtilis cultures: the direct-action adaptogenic factor XI capable of increasing bacterial resistance to unfavorable growth conditions (temperature and pH) and factor promoting adaptation to new media. Both factors are presumably low-molecular-weight hydrophilic nonprotein compounds.

Adaptation, Physiological↗
PubMedDate not supplied

[Saturated C21-C33 hydrocarbons are involved in the self-regulation of Pseudomonas fluorescens adhesion to a glass surface].

One of the two putative groups of antiadhesions was identified in Pseudomonas fluorescens by the method of gas chromatography-mass spectrometry. A mixture of high-molecular unbranched hydrocarbons (HC) with a chain length from 21 to 33 carbon atoms reduced cell adhesion to a glass surface. These HC accumulated in the culture liquid to a total concentration of 10-15 micrograms/l; the concentrations of individual HC ranged from 0.1 to 3.0 micrograms/l. After the addition of individual HC to the bacterial culture, the number of cells attached to the glass surface decreased. This decrease in cell adhesion was due to the enhanced aggregation of the bacterial cells, which promoted mechanical (hydrodynamic) cell detachment from the surface.

Bacterial Adhesion↗
PubMedDate not supplied

[Geobacillus uralicus, a new species of thermophilic bacteria].

The K2T strain of thermophilic spore-forming bacteria was isolated from a biofilm on the surface of a corroded pipeline in an extremely deep well (4680 m, 40-72 degrees C) in the Ural. The cells are rod-shaped, motile, gram-variable. They grow on a complex medium with tryptone and yeast extract and on a synthetic medium with glucose and mineral salts without additional growth factors. The cells use a wide range of organic substances as carbon and energy sources. They exhibit a respiratory metabolism but are also capable of anaerobic growth on a nitrate-containing medium and of fermentation. Growth occurs within the 40-75 degrees C temperature range (with an optimum of 65 degrees C) and at pH 5-9. The minimum generation time (15 min) was observed at pH 7.5. Ammonium salts and nitrates are used as nitrogen sources. The G + C content of the DNA is 54.5 mol%. From the morphological, physiological, and biochemical properties and the nucleotide sequence of the 16S rRNA gene, it was concluded that the isolate K2T represents a new species of the genus Geobacillus, Geobacillus uralicus.

Anaerobiosis↗
PubMedDate not supplied

[Growth and adhesion of Pseudomonas fluorescens in a batch culture: a kinetic analysis of the action of extracellular antiadhesins].

The work varifies 6 hypothetical models simulating the growth, respiration, and adhesion of cells to the walls of the cultivation flask. All the models postulate the synthesis of antiadhesins (AAs), i.e., extracellular metabolites decreasing the degree of cell adhesion. The models have the following distinguishing features: (model 1) the blocking of sorption centers on the glass walls by antiadhesins (the competitive inhibition of adhesion); (model 2) the noncompetitive inhibition of adhesion; (model 3) the accelerated release of bound cells; (model 4) a combination of models 1 and 3; (model 5) a combination of models 1 and 3 with a delay; (model 6) a combined action of two AAs, one of which, AA1, inhibits cell adhesion, and the other, AA2 (its synthesis is induced when the concentration of AA1 reaches a threshold level), stimulates the detachment of bound cells. Model 6 fits the relevant experimental data best. The delay effect is relatively small. The sigmoid character of the curve showing cell adhesion as a function of the antiadhesin concentration implies the existence of a strong cooperative effect in the adhesion inhibition. The models proposed satisfactorily simulate the growth, respiration, and adhesion of cells and AA synthesis in a batch bacterial culture grown either in a fresh nutrient medium or in the medium supplemented with the filtrate of a mature culture of the same species.

Adhesins, Bacterial↗
PubMedDate not supplied

[Extracellular protease as a reversible adhesion regulator in Pseudomonas fluorescens].

The investigation of growth dynamics and protein content in a batch Pseudomonas fluorescens culture grown in a synthetic medium with glucose as the sole source of carbon and energy showed that cells reversibly adhere to the walls of the cultivation flask during the first 2-3 h of growth. Over this time period, the total protein content of free and bound cells increased exponentially at a rate of 0.25 h-1, the fraction of proteins in cells being almost the same (60-70%). The protein content in the medium increased from 3 to 50 mg/l, reaching about 30% of the total protein of the culture. The addition of the exponential culture liquid filtrate to the medium together with the inoculum led to the complete inhibition of cell adhesion and a drastic activation of proteolysis, with a concurrent release of more than 80% of cellular proteins into the medium. After 3-5 h of growth, the concentration of extracellular proteins decreased to the control level. Exogenously added proteinase K inhibited cell adhesion, the effect being more pronounced for R-type than for S-type cells. The hypothesis is discussed that the short-term reversible adhesion of cells is regulated with the involvement of a mixture of hydrocarbons, which inactivate the functional activity of bacterial adhesins, and proteases, which digest these adhesins.

Adhesins, Bacterial↗