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Biomedical subjects

V A Bobrov

Publications and source records attributed to V A Bobrov.

At least 19 recordsLinked to original sources
PubMed2005

Disequilibrium between uranium and its progeny in the Lake Issyk-Kul system (Kyrgyzstan) under a combined effect of natural and manmade processes.

The Kadji-Sai abandoned field of U-bearing brown coal on the southern coast of Lake Issyk-Kul (Kyrgyzstan) poses a threat of radioactive pollution to the world's fifth deepest and second largest pristine highland lake. The valleys of ephemeral streams in the lake catchment are filled with coarse-grained sand and clay, with a background U--Ra activity of 35--55 Bqkg(-1). High activity areas vs. this background come from three sources: (1) scarce outcrops of uraniferous brown coal and mining wastes containing fragments of this coal with (238)U/(226)Ra ratios of 0.8 due to uranium losses through weathering; (2) manmade anomalies caused by a radioactive waste dump, where U was extracted from the ash of coal burnt at a coal-fired power plant. As a result, the (238)U/(226)Ra ratios become 0.15--0.25; (3) six catch pools terraced below the mine, where U activity decreases downslope, and (238)U/(226)Ra ratios reach 150--200. Uranium lost in the extraction process may have been retained on the terraces. The distribution pattern of radionuclides in the bottom sediments of the lake is controlled by water depth and offshore distance. The upper section of homogeneous limy--argillic deposits in the lake center remains undisturbed by currents, as indicated by regular sub-exponential distribution of atmospheric (137)Cs and (210)Pb(atm). Sedimentation rate in the lake center for the past century, found from (210)Pb, was 0.32 mmyr(-1). (238)U/(226)Ra in deep-water sediments was about 3. The activity of uranium adsorbed by sediments from the lake water was estimated by subtraction of the Ra-equilibrium component from the total U activity. Thus, the flux of dissolved U to the bottom sediments was as 2.07 x 10(-7)gcm(-2)yr(-1). The upper section of near-shore deposits was disturbed by currents, with (137)Cs and (210)Pb(atm) more or less uniformly distributed in this layer. Peaks of (226)Ra and (210)Pb occur at different depths from 5 to 20 cm below the sediment surface, with (238)U/(226)Ra ratios 0.28--0.44. The presence of mullite in these sediments indicated that radioactive ash penetrated into the lake in the past. At present, (226)Ra in the ash is buried under a non-radioactive cap.

Cesium Isotopes↗
PubMed1998

[Practical games as one of the forms for optimizing the academic process in physician postgraduate training].

Described in the article is one of the forms of optimization of the instructional process in the postgraduation physician training--"business-like games". Highly skilled, competent position of the teacher who conducts a business-like game secures an active participation in learning of students, helps in opening the mind, broadening the outlook on the problem under consideration, gives much incentive to further independent work on the discussed issues.

Diagnosis, Differential↗
PubMed1998

[The hormone level of the blood from the aorta and the coronary sinus in patients with ischemic heart disease under conditions of preoperative stress].

A total of 156 patients with ischemic heart disease were examined under conditions of preoperative stress in a multiple-modality study performed with the aid of such techniques as echocardiography involving calculation of the myocardial mass index, coronaroventriculography, measurements of the adrenocorticotrophic hormone, hydrocortisone, somatotrophic hormone, triiodothyronine and thyroxin in the blood from the coronary sinus and aorta. A conclusion has been reached that emotional strain influences myocardial hypertrophy. A possible significance of the studied hormonal indices is shown together with features thereof in IHD patients presenting with different degrees of left ventricular hypertrophy.

Adult↗
PubMed1997

Power spectrum analysis of circadian oscillations of heart rate variability in patients with left ventricular dysfunction.

OBJECTIVES: The physiological significance of diurnal fluctuations in heart rate variability (HRV) has not been established to a full extent. The aim of our investigation was to assess a new method of power spectrum analysis of circadian oscillations in HRV in patients with left ventricular systolic and diastolic dysfunction. METHODS: Holter ECG monitoring and echocardiography were performed in 101 patients with coronary artery disease and arterial hypertension: 55 patients with systolic left ventricular dysfunction (LVD) and 46 patients with diastolic LVD, and also in 32 subjects of the control group. The original method of HRV assessment was based on spectrum analysis of time series of consecutive 5-minute measures of standard deviations of mean RR intervals. RESULTS: The study revealed oscillations of HRV with a periodicity of 12 hours and 80-120 minutes. Their amplitude was highest in the control group and lowest in patients with systolic LVD. CONCLUSIONS: Power spectrum analysis of circadian oscillations of heart rate variability reveals information about the character of LVD. Regular oscillations of time domain indices of HRV were observed in the patients with LVD and in the control group; their amplitude is highest in the control group and lowest in systolic LVD.

Circadian Rhythm↗
PubMed1995

[The effect of calcium-regulating hormones on the renal transport of calcium in hypertension].

Enhanced and diminished calcemia following administration of parathormone and calcitonin in hypertensive patients, respectively, were found not to differ from relevant values in healthy subjects. Calciuretic effect of parathormone results from its action on the bone and renal calcium transport. Quantitatively, the effects on the bone and renal calcium transport. Quantitatively, the effects on the bone presenting as elevated calcemia and calcium filtration capacity, its excreted fraction and renal excretion prevail, being less pronounced in hypertensive patients. A direct renal effect of parathyroid hormone indicated by stimulation of calcium tubular reabsorption is weaker in hypertensive subjects. Calcitonin administration inhibits tubular calcium reabsorption in the less degree in hypertensive subjects. The disorders in calciuretic function of the kidney in hypertension are secondary to reduced kidney sensitivity to the action of calcium regulating hormones.

Adult↗
PubMed1994

[Neurocirculatory dystonia in patients with a chronic focal infection: the mechanisms of its formation and development].

Clinical manifestations of neurocirculatory asthenia (NA) were analyzed in 604 patients with associated chronic focal infection. It is shown that the latter infection produces negative effects on clinical symptoms of NA, its course, temporary disability and effectiveness of treatment. Vegetative reactivity and vegetative activity in NA patients with the infection were affected to a greater degree than in NA patients without the focal infection. The role of afferent impulses from the nasopharynx reflexogenic zone in the genesis of clinical specificity and vegetative regulation defects in NA patients is discussed.

Adult↗
PubMed1994

[Adaptation to physical and psychoemotional loads and mental work capacity in patients with neurocirculatory dystonia].

Mental performance and adaptation to exercise and psychoemotional loads were studied in 119 patients with neurocirculatory asthenia (NCA), 245 patients with chronic focal infection (CFI) of the upper airways, and 247 NCA patients with CFI. Exercise tolerance was measured at spiroergometry, intellectual and psychoemotional adaptation were assessed by shifts in attention and fatigue while working with Schulte tables under conditions of time limits and the results criticism, vegetative reactivity was tested with insulin and epinephrine, variation pulsograms recorded vegetative provision of physical, intellectual and psychoemotional activity. Abnormalities in mental performance and the above adaptation related to clinical presentation of NCA and CFI as well as to vegetative regulation were registered in NCA+CFI patients. Mechanisms of the alterations observed and the role of CFI in their genesis are discussed.

Adaptation, Physiological↗
PubMed1994

Comparative analysis of electrophysiologic effect of metoprolol and disopyramide, acting alone or in combination in patients with supraventricular tachycardia and Wolff-Parkinson-White syndrome.

In the aim of determining an electrophysiologic effect of disopyramide and metoprolol at alone therapy and in combination in patients with supraventricular tachycardia on the background of Wolff-Parkinson-White syndrome 23 persons were examined. All patients were subjected to an intracardiac electrophysiological testing; in its process metoprolol in the dosage of 0.2 mg/kg of body weight, disopyramide in the dosage of 2 mg/kg per body weight both separately and in combination were controlled. It was identified that metoprolol and disopyramide are an effective antiarrhythmic preparates applied for arresting and prevention of reciprocating orthodromic tachycardias in patients with Wolff-Parkinson-White syndrome.

Adult↗
PubMed1993

[Effects of laser irradiation of blood on electrical ventricular instability in patients with progressive angina pectoris].

The impact of laser blood irradiation (LBI) on electrical instability has been studied in 71 patients with progressive angina pectoris. The amount of couplets of ventricular premature beats after LBI was decreased, as evidenced by 24-hour monitoring. Invasive programmed ventricular stimulation provided better electrophysiological properties of the myocardium after LBI: primary examination showed that electrical ventricular instability was detected in 40%, but after the therapy it was only in 20% patients. Thus, LBI is an effective tool to decrease electrical ventricular instability, a major risk factor for sudden coronary death in patients with progressive angina pectoris.

Adult↗
PubMed1993

[The complex assessment of myocardial electrical instability in exacerbated ischemic heart disease].

Risk of sudden coronary death in patients with unstable stenocardia is studied insufficiently. 39 patients with unstable stenocardia underwent Holter's monitoring, loading tests and invasive programmed ventricular stimulation coming lately into increasingly wide use for assessment of myocardial electric stability. Programmed stimulation allowed to single out two groups of patients: with ventricular tachycardia (56.4%) and without it (43.6%). Results obtained by aforementioned methods showed no correlation which is explained by the authors as being due to different pathogenetical mechanisms initiating ventricular arrhythmias. Thus, for example, rhythm disorders emerged not infrequently in the periods of ischemia during Holter's monitoring while myocardial ischemia was not observed in all cases of programmed ventricular stimulation. That is why complex approach needs to be pursued for assessment of electric stability of myocardium in patients with advancing stenocardia.

Cardiac Complexes, Premature↗
PubMed1993

[Ventricular arrhythmias in patients with ischemic heart disease: a possible role of the autonomous nervous system].

To reveal possible factors that initiate ventricular arrhythmias (VA) in patients with coronary heart disease (CHD), a total of 44 patients with documented coronary artery stenosis were examined. The patients underwent coronary ventriculography, bicycle ergometry, 24-hour Holter monitoring, and examination of the autonomic nervous system (ANS). In 24 patients (Group 1), myocardial ischemic episodes were accompanied by VA. The latter were absent in myocardial ischemia in 20 patients (Group 2). In the two groups, there were no statistically significant differences in parameters, such as severity of atherosclerotic lesion of coronary arteries, total ejection fraction, existence of regional asynergy, exercise tolerance, number of daily myocardial ischemic episodes, their duration, degree of ST segment displacement. Increased activity of the sympathetic ANS was detected in 20 (83.3%) patients from Group 1 and only in 3 (15%) from Group 2 (p < 0.05). It is suggested that enhanced functional activity of ANS may be a prerequisite for displaying arrhythmogenic mechanisms in myocardial ischemia.

Adult↗
PubMed1993

[The optimization of the anti-arrhythmia effect of kordaron and novocainamide by laser biostimulation therapy in a combined program for treating refractory tachyarrhythmias].

Antiarrhythmic action of He-Ne laser in combination with novocainamid and cordaron has been tried in the framework of the program on combined treatment of tachyarrhythmia. He-Ne laser irradiation has been found to optimize in refractory patients the effect of novocainamid which arrests the paroxysms and of cordarone which prevents paroxysms of atrial tachycardia, fibrillation, flutter.

Acupuncture Points↗
PubMed1993

[Unstable angina: long-term dynamic observation based on the data from Holter ECG monitoring].

The choice of treatment of patients with unstable angina is one of the most important problems in cardiology. Establishment of its tactics is necessary both in hospital and in posthospital periods. 24-hour Holter monitoring is a safe and informative method which makes it possible to objectivize the state in such category of patients. In order to study the structure of ischemia and arrhythmias this approach was used in 50 patients with unstable angina at the first admission twice and also twice within the first year of follow-up. It was shown that stabilization which was achieved during the first hospitalization was retained in 58.2% during 1 year. In other cases increases of frequency, duration and significance of ischemia were observed. In the global structure of myocardial ischemia, silent ischemia composed 56-65%.

Angina, Unstable↗
PubMed1993

[The vasospastic component in the pathogenesis of unstable angina].

A comprehensive dynamic investigation revealed a group which included 31 (9.8%) patients with a response to the introduction of a probe-electrode during transesophageal pacing. It was characterized by ST-segment elevation and development of an anginal attack. The hemostatic parameters examined suggest that there is a special group among patients who have unstable angina with increasing vasospastic activity. The introduction of a probe-electrode may be considered to be a provocative test.

Angina, Unstable↗