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Biomedical subjects

A A Ovchinnikov

Publications and source records attributed to A A Ovchinnikov.

At least 19 recordsLinked to original sources
PubMed2004

[Application of endostents in tumor and scarry stenoses and main bronchi].

To evaluate advantages and shortcomings of Dumon's, T-shape and polyflex endotracheal stents in patients with tumor and scarry stenoses of the trachea and main bronchi, we analysed the results of stenting trachea and main bronchi in 180 patients for 11 years (1992-2002). We observed the highest rate of granulations and dislocations for polyflex stents in the lowest adhesion of the sputum to their walls. Long-term results of stenting in scarry tracheostenosis demonstrate a moderate efficacy of T-stents and low efficacy of Dumon's stents. Our final conclusion is that a key method of treatment of tracheal scarry stenoses is a circulatory resection of the stenosed zone. Tracheal stenting remains important in urgent necessity of the treatment of decompensated stenoses, in preparation for radical operation and in contraindications to the latter.

Adolescent↗
PubMed2002

Broken space-time symmetries and mechanisms of rectification of ac fields by nonlinear (non)adiabatic response.

We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries, which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is employed to explain the effect. We consider a case of a particle in a periodic potential as an example and discuss the relevant symmetry breakings and the mechanisms of rectification of the current in such a system.

Journal Article↗
PubMed2001

Long-time tails in the kinetics of reversible bimolecular reactions.

A new approach is developed to study the relaxation of concentrations to equilibrium in reversible bimolecular reactions. For A+B <==> C, a general analytic expression is derived for the amplitude of the power law (t(-d/2)) asymptotics for arbitrary diffusion coefficients and concentrations of the reactants. Our formalism is based on the analysis of the time correlation functions describing the equilibrium fluctuations of the concentrations. This powerful and simple procedure can be readily used to study other bimolecular reactions such as A+B <==> C+D.

Journal Article↗
PubMed1995

[Intercellular interactions in morphogenesis of initial lesions and sclerosis in interstitial lung diseases].

A total of 117 patients with pulmonary interstitial diseases (PID) were examined. The functional activity of alveolar macrophages was assayed in the lavage fluid and in lung tissue biopsy specimens from the generation of active oxygen forms, the secretion of tumor necrosis factor, fibronectin, expression of c-fos- and c-sis-oncoprotein. The stereotypic value for various PID was the development of alveolitis running in 2 stages: 1) early one, including exudative inflammation and 2) late one, involving sclerotic changes up to the formation of the honeycomb lung. This results in the block of the blood-air barrier and progression of respiratory failure and hypoxia in patients. The morphogenesis of fibrosing alveolitis is formed of alveolar septal damages caused by etiological agents of various nature, which is frequently unclear, by active forms of oxygen, lipid peroxidation products, proteases, tumor necrosis factor, which are produced by activated alveolar macrophages and polymorphonuclear leukocytes. The alveolar macrophage that secretes growth factors, c-fos- and c-sis-oncoproteins plays the key role in the progression of sclerotic changes. Lung cancer may develop at the end of fibrosing alveolitis at the stage of the honeycomb lung.

Adolescent↗
PubMed1995

[Interstitial lung diseases--the clinical aspects of the problem].

Upon analysis of 550 cases of different chronic diffuse pulmonary diseases included in a group of interstitial diseases of the lungs (IDL) the authors came to the conclusion that IDL incorporate such variants as alveolitis, pulmonary vasculitis and pulmonary hemorrhages; granulomatosis covers exogenic allergic alveolitis, alveolitis in chronic active hepatitis; vasculitis group includes such rare diseases as necrotizing sarcoid granulomatosis vasculitis and lymphoid granulomatosis; fibrosing alveolitis--secondary alveolitis in sclerodermia systematica, rheumatoid arthritis, Sjogren's disease, chronic active hepatitis. Knowledge of IDL etiology (environmental, occupational, induced by radionuclides, drugs, viruses, fungi) with focus on drug affection of the lungs is thought of value. Biopsy and bronchial lavage findings are compared clinically and morphologically. Mechanisms of pulmonary fibrosis and approaches to inhibition of pulmonary fibrosis progression are outlined.

Adult↗
PubMed1995

[Variants and stages in the course of idiopathic fibrosing alveolitis].

Clinicomorphological analysis covered 41 cases of idiopathic fibrosing alveolitis (IFA). The comparison of the degree of respiratory insufficiency, hypoxia, survival of the patients with cytogram of the bronchoalveolar lavage, morphological findings, generation of active oxygen forms by alveolar macrophages and leukocytes has provided evidence on an important role of alveolar macrophage in interstitial alveolitis and fibrosis in IFA. Three variants of chronic IFA are distinguished: aggressive, persistent and slowly progressive. The variants have different prognosis and need individual therapeutic approach.

Adult↗
PubMed1995

[The clinico-morphological characteristics of interstitial lung diseases].

Electron microscopic and immunohistochemical methods were employed to study composition of collagens in extracellular matrix and quantify oncoproteins c-sis and c-fos. It was established that interstitial pulmonary diseases of various etiology are characterized at early stages by alveolitis with activation of alveolar macrophages, at late stages by interstitial fibrosis with accumulation of collagens type I, III, IV and V and epithelial dysplasia which is likely to initiate bronchioloalveolar cancer.

Adult↗
PubMed1991

[The extracellular matrix of peripheral lung cancer in the scar and of pneumosclerosis of different origins (the immunohistochemistry and electron microscopy of the collagens)].

Collagen types and ultrastructural features of the stroma and scar extracellular matrix in the peripheral lung carcinoma, post-tuberculosis and post-pneumonia pneumosclerosis foci, fibrosing alveolitis interstitium were studied on the material of operational and transbronchial lung biopsies. It is established that by the collagen composition the scars in the peripheral carcinoma are identical to the pneumosclerosis foci and are distinguished from the carcinoma stroma by a higher concentration of type IV and V collagens (p less than 0.05). Accumulation of type III collagen in the lung carcinoma stroma reflects anaplasia of the tumour as the domination of type III collagen is characteristic of the embryonal tissue. The decrease of collagen type IV in the cancer stroma correlates with an increase of its malignancy. Pneumosclerosis in the fibrosing alveolitis is distinct from the focal forms of pneumosclerosis by a higher content of collagen I and a lower content of collagen V this being probably due to the character of sclerosis morphogenesis in this disease.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

On the methods of disinfecting bronchofibroscopes.

An apparatus is proposed for the wet disinfection of bronchofibroscopes which enables to wash with disinfectant solution the external surfaces of the tube and instrument channel while keeping dry the control mechanism. Several disinfecting regimens have been tested using chlorohexidine (Gibitan), benzalkonium chloride (Roccal), diocide and ethanol solutions. On experimental contamination of bronchofibroscopes with a P. aeruginosa culture effective disinfection was achieved using 0.5% aqueous and ethanol solution of chlorohexidine and 1% benzalkonium chloride solution (5-min, exposure in the circulation mode of the apparatus), 0.1% solution of diocide only produced a bactericidal effect after a 30-min, exposure. Adequate disinfection was not feasible when the endoscope was soaked in disinfectant. Similar results were obtained when bronchofibroscopes were disinfected in a clinical setup where they became contaminated with the most common pathogenic and potentially pathogenic microflora from the airways of patients suffering from purulent pulmonary diseases.

Benzalkonium Compounds↗
PubMed1989

Structural basis of steroid compounds interaction with "digitalis"-receptor sites of Na,K-dependent ATPase.

Twenty-two Steroid molecules have been tested for the inhibition Na,K-dependent ATPase at 10(-7)-10(-4) M concentrations. At the 10(-5) M concentration of the investigated molecules, inhibition ranged from 8 to 36%. To explain the structure-inhibition % relationship, we determined the value of heteropolarity or biphilicity moment of these molecules. This value would appear to be dependent on the space location and hydrophilicity of the molecule elementary fragments, and to the degree of their water accessibility; however, it is independent of the hydrophilicity of the molecules as a whole. On the basis of the obtained data, details of Na,K-ATPase digitalis-receptor structure and the mechanism of the glycoside-receptor interaction are discussed.

Binding Sites↗
PubMed1989

[Disorders of immune reactivity in chronic bronchitis].

The cytologic and immunologic analysis of bronchoalveolar washing offs and of peripheral blood was made in 45 patients with chronic bronchitis. Of these, 27 patients suffered from catarrhal bronchitis without infection signs and 18 were affected with purulent bronchitis with superinfection. It has been shown that discovery of a considerable number of neutrophils in the bronchoalveolar washing offs promotes the establishment of the infectious etiology of chronic bronchitis. The immunologic analysis of the washing offs was found to be of great informative value in the study of the mechanism of the disease development. Pronounced dysfunction of the immune system and its manifestations common to catarrhal and purulent bronchitis were demonstrated. It is concluded that dystrophic processes predominate in the lungs of the patients with chronic purulent bronchitis whereas catarrhal bronchitis is marked by the high local immune reactivity in the lungs. The characteristic features revealed are regarded as criteria of the differential diagnosis between the given bronchitis patterns. It has been disclosed that impairment of the mechanisms of cellular immunity is one of the properties shared by both the disease patterns. The authors discuss the prospects of the use of the combined immunologic analysis of the bronchoalveolar washing offs and peripheral blood in patients with chronic bronchitis.

Adolescent↗
PubMed1986

[Transbronchial biopsy in the diagnosis of sarcoidosis and certain other interstitial lung diseases].

Results of transbronchial pulmonary biopsy studies of patients of different sex and age suffering from interstitial pulmonary lesion are presented. Different diagnostic value of transbronchial pulmonary biopsy (TBBP) is shown in relation to different lesions. In case of sarcoidosis its informative value, for example, is high, while in the diffuse processes such as cryptogenic fibrosing alveolitis, the data allow only suggestive diagnosis and recommendation of an open lung biopsy. In chronic nonspecific pulmonary diseases TBBP helps to clarify the character and the activity of the process involved. In some cases it is possible to reveal a latent cancer. It is suggested to use the term "allergic alveolitis" (indicating the mechanism of development of changes mentioned) when such changes as alveolitis, small granulemas and intraalveolar outgrowths are found in the biopsy specimens.

Adolescent↗
PubMed1985

[The use of theoretical conformation analysis in the study of the mechanism of interaction of carbohydrate components of cardiac glycosides with receptor].

The conformational possibilities for sugar components of cardiac monoglycosides have been analyzed. A comparison of spatial disposition of oxygen atoms in the energetically allowed conformations of these residues permitted unambiguous determination of 1) monosaccharide bioactive conformations; 2) their functional groups involved in the receptor binding; 3) coordinates of the region wherein the oxygen atom should be accomodated in order to be bound to the receptor. It was shown that the conformational lability and the presence of several oxygen-containing groups in the first monosaccharide residue underlie the possibility for coexistance of several productive conformations. The rules for qualitative predictions of the carbohydrate contribution into biological activity of cardiac glycosides were formulated. A number of monosaccharide residues were distinguished that should have either favorable or unfavorable effects on the biological activity of cardenolides.

Cardiac Glycosides↗