PubMed Health⌕ Search

Biomedical subjects

V P Nikolaev

Publications and source records attributed to V P Nikolaev.

At least 19 recordsLinked to original sources
PubMed2001

[Improved technology of chemotherapy of pulmonary tuberculosis complicated by other diseases].

Ample clinical material obtained in Yakutia was used to study the efficiency of combined treatment in patients with disseminated pulmonary tuberculosis concurrent with gastrointestinal and respiratory diseases. At the same time it was justifiable to employ alternatives to deliver antituberculous agents to the lesion focus (rectal dropwise administration, phono- and photophoresis of isoniazid, endobronchial colloid diluted rifampicin, and activated silver water diluted antituberculous drugs) with additional biophysical exposure. This made this group of patients have much better antituberculous agent intolerance, which increased nonbacterial isolation rates and closed decay cavities as compared with conventional methods for administering antituberculous agents.

Animals↗
PubMed2000

Effects of heterogeneous structure and diffusion permeability of body tissues on decompression gas bubble dynamics.

To gain insight into the special nature of gas bubbles that may form in astronauts, aviators and divers, we developed a mathematical model which describes the following: 1) the dynamics of extravascular bubbles formed in intercellular cavities of a hypothetical tissue undergoing decompression; and 2) the dynamics of nitrogen tension in a thin layer of intercellular fluid and in a thick layer of cells surrounding the bubbles. This model is based on the assumption that, due to limited cellular membrane permeability for gas, a value of effective nitrogen diffusivity in the massive layer of cells in the radial direction is essentially lower compared to conventionally accepted values of nitrogen diffusivity in water and body tissues. Due to rather high nitrogen diffusivity in intercellular fluid, a bubble formed just at completion of fast one-stage reduction of ambient pressure almost instantly grows to the size determined by the initial volume of the intercellular cavity, surface tension of the fluid, the initial nitrogen tension in the tissue, and the level of final pressure. The rate of further bubble growth and maximum bubble size depend on comparatively low effective nitrogen diffusivity in the cell layer, the tissue perfusion rate, the initial nitrogen tension in the tissue, and the final ambient pressure. The tissue deformation pressure performs its conservative action on bubble dynamics only in a limited volume of tissue (at a high density of formed bubbles). Our model is completely consistent with the available data concerning the random latency times to the onset of decompression sickness (DCS) symptoms associated with hypobaric decompressions simulating extravehicular activity. We believe that this model could be used as a theoretical basis for development of more adequate methods for the DCS risk prediction.

Atmospheric Pressure↗
PubMed1999

[The monitoring of gas bubbles with a pulsed Doppler ultrasonic locator in humans working in a space suit].

Presented are results of gas bubbles monitoring in decompressed humans with the use of an ultrasonic pulse-Doppler locator (PDL). Unlike the classic Doppler bubbles detectors with continuous US emission, PDL is adjusted for reception of echo from a chosen volume of the right ventricle cavity; thus, the clutter due to cardiac beats and human locomotion is successfully rejected. During simulation of Russian EVAs, venous gas bubbles were detected in 3 out of 5 experiments with test-subjects clothed in everyday wear and in 2 out of 3 experiments with suited test-subjects.

Adult↗
PubMed1998

[Analysis of decompression safety during extravehicular activity of astronauts in the light of probability theory].

Objectives of the study were comparative assessment of the risk of decompression sickness (DCS) in human subjects during shirt-sleeve simulation of extravehicular activity (EVA) following Russian and U.S. protocols, and analysis of causes of the difference between real and simulated EVA decompression safety. To this end, DCS risk during exposure to a sing-step decompression was estimated with an original method. According to the method, DCS incidence is determined by distribution of nucleation efficacy index (z) in the worst body tissues and its critical values (zm) as a function of initial nitrogen tension in these tissues and final ambient pressure post decompression. Gaussian distribution of z values was calculated basing on results of the DCS risk evaluation on the U.S. EVA protocol in an unsuited chamber test with various pre-breath procedures (Conkin et al., 1987). Half-time of nitrogen washout from the worst tissues was presumed to be 480 min. Calculated DCS risk during short-sleeve EVA simulation by the Russian and U.S. protocols with identical physical loading made up 19.2% and 23.4%, respectively. Effects of the working spacesuit pressure, spacesuit rigidity, metabolic rates during operations in EVA space suit, transcutaneous nitrogen exchange in the oxygen atmosphere of space suit, microgravity, analgesics, short compression due to spacesuit leak tests on the eye of EVA are discussed. Data of the study illustrate and advocate for high decompression safety of current Russian and U.S. EVA protocols.

Astronauts↗
PubMed1997

[Specific features of tuberculosis in the similar biogeochemical subareas of the biosphere in the Chuvash and Sakha (Iakutia) republics].

The use of biogeochemical zoning of the territories of the Chuvash and Sakha (Yakutia) Republics revealed that due to silicon deficiency in the food biogeochemical chain, the indigenous population had reduced cellular immunity, accumulated residual tuberculous changes leading to higher morbidity, disease aggravation, more frequent complications, high tuberculosis mortality.

Adult↗
PubMed1997

[Evaluation of the risk of decompression disease during hypobaric decompression from the standpoint of the probability theory].

Author's probabilistic theory of decompression sickness (DS) asserts that DS risk for human subjects during a single-stage reduction of pressure will be rated by distribution of estimated nucleation efficiency in the "worst" body tissues and its critical value as a function of initial nitrogen pressure, end-pressure, and bubble growth dynamics. The method was tested in the analysis of literature on the DS risk during altitude exposures with preliminary denitrogenation of varying length. Results of the analysis suggest that washing out half of nitrogen from the "worst" tissues will take minimum 480 minutes instead of 360 minutes. Calculated parameters of nucleation in tissues were used to plot DS risk due to hypobaric decompression against the final pressure. Influence of physical activity on nucleation parameters and DS risk curves is discussed.

Decompression↗
PubMed1992

[Outpatient observation and treatment of patients with tuberculosis and massive bacterial excretion aggravated by negative social factors].

Social and epidemiologic features were studied in 1145 newly diagnosed tuberculosis patients in Yakutia who were on the dispensary record in the period between 1981 and 1990. Among the negative social and hygienic factors which aggravated the course of tuberculosis were unsatisfactory living and domestic conditions, failure in family life, unskilled hard labour, idle life, stay in the penitentiary-labour establishments and chronic alcoholism. To improve the effectiveness of dispensary follow-up and treatment of this category of patients measures should be taken aimed at the centralized epidemiologic control. They include, registration of copious bacilli excretors as a special contingent of antituberculosis dispensaries, active measures directed against drug addiction and removal of the unfavourable psychologic factors as well as obligatory hospitalization of patients into specialized tuberculosis centres.

Adult↗
PubMed1991

[A natural focus of sandfly fever in the Republic of Afghanistan].

The serological study of persons contacting dengue-like fever in 1987 in Afghanistan (in Rukha, Parwān Province) revealed that in 74% of cases an increase in the titers of antibodies to Sicilian and Neapolitan sandfly [correction of mosquito-borne] fever viruses was registered. Considering that such diseases appeared here for a number of years and were linked in time with the activity of sandflies [correction of mosquitoes] of the species Phlebotomus papatasii, the suggestion was made on the existence of a stable natural focus of sandfly [correction of mosquito-borne] fevers in the region of Rukha.

Afghanistan↗