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Biomedical subjects

A S Kuznetsov

Publications and source records attributed to A S Kuznetsov.

At least 19 recordsLinked to original sources
PubMed2005

Regularization of dynamics in an ensemble of nondiffusively coupled chaotic elements.

We investigate the dynamics in an ensemble of chaotic elements with nondiffusive coupling. First, we analyze the case of global coupling. The type of coupling we consider leads to the suppression of oscillations in the whole ensemble at a high coupling strength. A distinct feature of this transition from high-dimensional chaos at a low coupling strength to the stationary state is that there is no partially ordered phase characterized by a large number of coexisting synchronized clusters. A two-cluster mode emerges abruptly, replacing the asynchronous mode. We focus on the influence of connectivity on the dynamics in the two-cluster modes and their domains of existence. We introduce a parameter that characterizes the connectivity: the range of coupling. Our computational and analytical results indicate that the most significant changes in the dynamics occur in the case of local coupling, when extra connections are added. By contrast, if the range of coupling is high, even substantial changes in this range have a small influence on the dynamics.

Journal Article↗
PubMed2003

[Use of permanent pacemakers in children].

The experience of pacemakers use in 24 children aged 6-15 years in the treatment of arrhythmias and conduction disturbances (CD) were summarized. Surgical intervention is indicated when a medical history of syncope or severe hemodynamic disturbances is present. In order to achieve a high quality of life of the child with arrhythmias and CD it is essential to use up-to-date pacemaker models with 2-chamber stimulation, frequency modulation, telemetry and prolonged expiry term.

Adolescent↗
PubMed2002

Stable heteroclinic cycles for ensembles of chaotic oscillators.

We study the formation of synchronous clusters in ensembles of globally coupled chaotic oscillators. We reveal that at least three clusters of identical synchronization are formed in such a system for large enough values of coupling strength. Our main result is an unexpected intermittent process of clusterization. This process gives strong indication to the existence of a stable heteroclinic cycle.

Journal Article↗
PubMed2001

On the ability of high density lipoproteins to remove phospholipid peroxidation products from erythrocyte membranes.

To study the transfer of oxidized phospholipids from cell membranes to high-density lipoproteins (HDL), human Cu2+-oxidized erythrocyte membranes were incubated with HDL3 subfraction for 17 h at 37 degrees C followed by isolation of the supernatant, precipitation from it of HDL3, and determination of lipid peroxide products (LPP) in them. The incubation increased the content of lipid hydroperoxides in HDL3 significantly (by 32 and 40% calculated per ml of sample or mg of protein) and of malondialdehyde (by 27 and 34%, respectively) compared to control (incubation of HDL3 alone). The content of conjugated dienes did not change significantly. Fluorescence analyses of isolated HDL3 particles showed that the content of fluorescent products (lambdaex = 365 nm, lambdaem = 430 nm) in them was 2.5 times higher than in control, and the number of binding sites for the 1-anilinonaphthalene-8-sulfonic acid probe decreased by 22%. This also confirms accumulation of LPP in the lipoprotein subfraction. It seems likely that an increase in LPP (at least hydroperoxides) in HDL3 after their incubation with oxidized membranes occurs via transport of phospholipids containing LPP from erythrocyte membranes to lipoproteins. The data on the ability of HDL3 to accept LPP from erythrocyte membranes in vitro suggest that HDL3 may have a protective action on cell membranes undergoing oxidation in vivo as well.

Anilino Naphthalenesulfonates↗
PubMed1998

[The carotid sinus syndrome: problems and outlook].

Electrocardiostimulator was implanted in 108 patients for the carotid sinus syndrome. In 38 observations ventricular stimulation was applied, in 19--the two-chamber one and in 51--the atrial. The syncope disappearance was observed while the DDD and AAI modes of stimulation. If the atrioventricular conduction disorder do not occur while doing transoesophageal stimulation of left atrium during the provocation tests the atrial stimulation is indicated.

Adolescent↗
PubMed1997

[Ways of decreasing lethality in various forms of bradyarrhythmia].

Hospital mortality analysis in patients with different kinds of bradyarrhythmias after electrocardiopacemaker implantation operation performance was conducted. Significant haemodynamics improvement did not occur, if the patients had the pronounced coronary atherosclerosis. It was concluded that combined surgical correction of this pathology is needed.

Adult↗
PubMed1995

"Essential" phospholipids versus nicotinic acid in the treatment of patients with type IIb hyperlipoproteinemia and ischemic heart disease.

In patients with moderate, dietary noncorrigible hyperlipoproteinemia type IIb and ischemic heart disease, treatment with nicotinic acid is limited by the side effects of the drug. In 100 patients, 6-month treatment with nicotinic acid (n = 50) or "essential" phospholipids (EPL); Lipostabil, manufacturer: Rhône-Poulenc Rorer) (n = 50) indicated comparable efficacy for both substances: Significant (p < .001) reductions of serum total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride values were similar in both groups, while nicotinic acid increased high-density lipoprotein (HDL) cholesterol significantly (p < .01) better than Lipostabil. A detailed analysis of ultracentrifugal lipoprotein profiles, hydroperoxide concentrations in LDL, and cholesterol-accepting properties of HDL in a small number of Lipostabil- and nicotinic acid-treated patients revealed favorable shifts in the lipoprotein profile, significant (p < .05) reductions of LDL hydroperoxides, and favorable increases of the most antiatherogenic HDL2b subfraction only in the Lipostabil-treated group. Clinically, both medications reduced the intensity and number of angina pectoris attacks per week (p < .05), but only Lipostabil-treated patients significantly (p < .05) increased their working capacity in the veloergometric test. Since in the nicotinic acid-treated group dropouts (nine patients, eight related to the drug) and side effects [14] exceeded those in the Lipostabil-treated group (two dropouts not related to the drug, no side effects), it is suggested that Lipostabil is a preferable alternative in the treatment of patients with moderate, dietary noncorrigible hyperlipoproteinemia IIb and ischemic heart disease.

Cholesterol, HDL↗