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Biomedical subjects

V S Volkov

Publications and source records attributed to V S Volkov.

At least 19 recordsLinked to original sources
PubMed2006

[The pathogenesis of arterial hypertension in patients with type II diabetes].

The aim of the study was to define more exactly the role of high salt consumption in the pathogenesis of arterial hypertension (AH) in patients with type II diabetes. The subjects, 110 patients with type II diabetes accompanied by AH (mean age 55 +/- 1.7 years), were divided into three groups according to their salt gustatory sensitivity threshold (SGST). The comparison and control groups consisted of 134 patients with essential AH, and 30 practically healthy individuals, respectively. Among the patients with type II diabetes and AH, the study revealed patients with special manifestations such as high SGST, numerous complaints, frequent hypertonic crises, higher blood pressure (BP), and BP circadian rhythm disorder consisting in insufficient nighttime BP decrease. The study demonstrated a significant role of high salt consumption in AH pathogenesis in this group of patients.

Blood Pressure↗
PubMed2006

[The role of intravascular autorossette-formation in the onset of anemia in patients with chronic cardiac failure].

AIM: To study intensity of intravascular autorossette-formation (ARF) and its role in development of anemia in patients with chronic heart failure (CHF). MATERIAL AND METHODS: Blood smears (Romanovsky-Gimze stain) were obtained from 210 patients with CHF (functional class I-III) treated as indicated. Total number of autorossettes (AR) and AR with red cell lysis in them were calculated in the blood smears. RESULTS: The number of endogenic AR increases with higher functional class of CHF, duration of the disease, number of drugs. With increasing number of AR and AR with exocytic lysis, number of red cells and blood hemoglobin concentration lower. CONCLUSION: It is suggested that phenomenon of intravascular autorossette-formation is involved in pathogenesis of anemia in CHF patients and a cause of anemia may be much more complicated that it was thought initially.

Aged↗
PubMed2004

Development of equipments for determination of BNCT source spectral parameters.

The knowledge of neutron and gamma ray energy spectra can strongly influence the BNCT information about delivered dose to target volume as well as to the surface healthy tissue region. This region is very often decisive to stay within the recommended healthy tissue limit. Modification of neutron Bonner spectrometer to one block i.e. Bonner spectrometer monoblock (BSM) and gamma ray Si semiconductor spectrometer are being developed and verified in real conditions of LVR-15 reactor beam. Test measurements were also carried out in conditions of known standard spectra. The accepted procedure and the first results documenting the sensitivity BSM to different spectra are presented.

Boron Neutron Capture Therapy↗
PubMed2004

Near-field imaging of organic nanofibres.

The optical near-field of orientated nanofibres of para-hexaphenyl was investigated by a combination of localized far-field ultraviolet excitation and scanning near-field fluorescence detection. Morphological inhomogeneities of the nanofibres together with selective incoupling into the near-field probe resulted in a detection sensitivity was dependent on individual nanoaggregates. Strongest near-field intensity and radiation into the far-field were observed at the crossing points of nanofibres. The near-field observation of a distance-dependent damping of the waveguiding along the nanofibres allowed us to determine the imaginary part of the dielectric function of the nanofibres, in quantitative agreement with far-field optical data.

Journal Article↗
PubMed2004

[Clinical and functional characteristics of hypertension in patients consuming excessive amounts of salt].

Salt sensitivity threshold was measured in 230 patients with arterial hypertension and clinical and functional characteristics of hypertension in patients consuming excessive amounts of salt were studied. Patients with high salt sensitivity threshold consumed more salt with food and represented a special group of patients. These patients suffered especially severe disease which developed earlier than in patients with low threshold. Patients with high salt sensitivity threshold more often had cardiovascular complaints, neurotic traits in psychological status, aggravated heredity. These patients had higher cholesterol level and more often smoked. Clinical course of the disease in patients with high salt sensitivity threshold was more often complicated by hypertensive crises. They also had higher blood pressure throughout 24 hours and impaired circadian blood pressure rhythm. Increased myocardial volume load in patients with high salt sensitivity threshold promoted rapid development of left ventricular hypertrophy and systolic dysfunction.

Cholesterol↗
PubMed2003

Surface plasmon polariton waveguiding in random surface nanostructures.

In this study, guiding of surface plasmon polaritons excited at a gold film surface along corrugation-free channels in regions that are covered with randomly located surface scatterers, is considered using near-field microscopy for imaging of surface plasmon polariton intensity distributions at the surface. In the wavelength range 713-815 nm, we observed complete inhibition of the surface plasmon polariton propagation inside the random structures composed of individual ( approximately 70 nm high) gold bumps (and their clusters) placed on a 55 nm thick gold film with a bump density of 75 micro m-2. We demonstrate well-defined surface plasmon polariton guiding along corrugation-free 2 micro m wide channels in random structures and, in the wavelength range 738-774 nm, low-loss guiding around 20 degrees bends having a bend radius of approximately 15 micro m.

Gold↗
PubMed2003

Experimental studies of surface plasmon polariton band gap effect.

Surface plasmon polaritons (SPPs) propagation at a gold film surface covered by periodic arrays of approximately 40-nm-high scatterers arranged in a triangular lattice of different periods containing straight line defects is studied using collection scanning near-field optical microscopy. The results reveal the dependence of the SPP band gap (SPPBG) effect manifested via the SPP reflection and guiding (along line defects) on the parameters of the surface structures (period, filling factor and lattice orientation). We find that the SPPBG effect is stronger along GammaK direction for all investigated periodic structures. Our results demonstrate that the SPPBG effect becomes less pronounced with a decrease of the filling factor and disappears for a filling factor close to 0.2. We also observe that the centre of the SPPBG shifts towards longer wavelengths with an increase of the lattice period.

Journal Article↗
PubMed2003

Distribution of xylem hydraulic resistance in fruiting truss of tomato influenced by water stress.

In this study xylem hydraulic resistances of peduncles (truss stalk), pedicels (fruit stalk) and the future abscission zone (AZ) halfway along the pedicel of tomato (Lycopersicon esculentum L.) plants were directly measured at different stages of fruit development, in plants grown under two levels of water availability in the root environment. The xylem hydraulic connection between shoot and fruits has previously been investigated, but contradictory conclusions were drawn about the presence of a flow resistance barrier in the pedicel. These conclusions were all based on indirect functional measurements and anatomical observations of water-conducting tissue in the pedicel. In the present study, by far the largest resistances were measured in the AZ where most individual vessels ended. Plants grown at low water availability in the root environment had xylem with higher hydraulic resistances in the peduncle and pedicel segments on both sides of the AZ, while the largest increase in hydraulic resistance was measured in the AZ. During fruit development hydraulic resistances in peduncle and pedicel segments decreased on both sides of the AZ, but tended to increase in the AZ. The overall xylem hydraulic resistance between the shoot and fruit tended to increase with fruit development because of the dominating role of the hydraulic resistance in the AZ. It is discussed whether the xylem hydraulic resistance in the AZ of tomato pedicels in response to water stress and during fruit development contributes to the hydraulic isolation of fruits from diurnal cycles of water stress in the shoot.

Solanum lycopersicum↗
PubMed2003

[Role of duodenogastric reflus in pathogenesis of duodenal ulcer].

Duodenal ulcer is characterized by certain recurrence and occurs more often in men than in women. One can assume that functional changes, which are characterized by the seasonal nature and sex differences, play some role in its pathogenesis. There was a study of the duodenogastric reflux role in the pathogenesis of duodenal ulcer. It was revealed that duodenal reflux is provoked in about one half of patients sent for an endoscopic examination, less frequently--in spring and autumn, and least of all--in male patients with duodenal ulcer during seasons of the maximum frequency of duodenal ulcer exacerbations. The frequency of duodenogastric reflux provocation went down on days of geomagnetic storms. One could observe certain dependence between the extent and duration of reflux, on the one hand, and clinical registration of the disease, on the other hand.

Duodenal Ulcer↗
PubMed2003

[Gastroduodenal reflex in duodenal ulcer and chronic hyperacidic gastritis].

AIM: To study motor and secretory function of the stomach and duodenum in duodenal ulcer (DU) and chronic hyperacidic gastritis (CHG). MATERIAL AND METHODS: Autonomic nervous system was studied and esophagogastroduodenoscopy, 24-h intragastric pH-metry were made in 42 DU and 20 CHG patients. RESULTS: In comparable secretion, the patients of the above groups differed by severity and frequency of duodenogastric reflux (DGR). Grave and moderate DGR was typical for CHG and DU in the absence of complications. Minimal DGR occurred in DU with complications. CONCLUSION: DGR severity may be of prognostic significance for DU course.

Chronic Disease↗
PubMed2003

[Assessment of coronary reserve in patients after myocardial infarction].

Clinical data were compared with results of stress tests (veloergometry and transesophageal cardiac pacing) in 320 patients 1.5-2 months after myocardial infarction. Severity of angina was classified as functional class 0, I, II, III and IV in 78 (24.4%), 162 (50.6%), 64 (20%), 12 (3.75%), and 4 (1.25%) patients, respectively. Characteristics of coronary reserve by exercise test and transesophageal pacing considerably differed mostly in patients with class 0 and I and were practically identical in patients with class III and IV angina. Pearson's coefficient of correlation was the highest between clinical data and results of transesophageal pacing. It was lower between results of pacing and veloergometry and the lowest between clinical data and results of veloergometry. Values of Pearson's coefficient of correlation rose with increase of functional class of angina from 0.38 to 0.88. All methods analyzed in this study were reliable for estimation of degree of lowering of coronary reserve in patients with high functional class of angina. However in patients without angina or with class I angina additional methods were required and transesophageal cardiac pacing appeared to be a preferable technique for assessment of level of coronary reserve in these patients.

Adult↗
PubMed2003

[Salt consumption and arterial hypertension].

Solution of the problem of hypertension lies in prevention. And here it is impossible to get along without risk factor concept. Most valuable risk factor for development of hypertension is salt - sodium ion at first hand. Increased salt intake with diet modifies effect of such important risk factors of hypertension as aggravated heredity, excessive body mass, low physical activity, alcohol, etc. Thus heredity can be realized through decreased sensitivity of taste receptors of the tongue causing involuntary excessive sodium consumption. The authors believe that it is restriction of salt intake that will make prevention of hypertension feasible.

Health Knowledge, Attitudes, Practice↗
PubMed2003

[The phenomenon of intermittent myocardial ischemia and characteristics of myocardial reserve in patients with myocardial infarction].

AIM: To study coronary and myocardial reserves in myocardial infarction survivors (MIS) with consideration of development of intermittent ischemia during transesophageal pacing (TEP). MATERIAL AND METHODS: 320 MIS were examined 1.5-2 months after myocardial infarction onset. 30 healthy male volunteers served control. Stepwise overdrive TEP was made in all the examinees with parallel estimation of central hemodynamics by tetrapolar chest rheography with assessment of systolic and diastolic parameters. RESULTS: In the course of TEP, 39.4% MIS developed intermittent ischemia (II) at frequencies 120-140 imp/min. II presented as a significantly depressed ST segment on ECG. There was a simultaneous lengthening (1.4-fold) of diastole and a fall (1.5-fold) of end-diastolic pressure in the left ventricle (EDP). At frequencies 140-160 imp/min the length of the diastole shortened while EDP rose. CONCLUSION: The II phenomenon demonstrates a key role of coronary reserve. Changes in coronary and myocardial reserves during TEP in II development are interrelated. They may represent unknown adaptive mechanisms of the myocardium protecting against unfavourable outcomes of ischemic episodes.

Blood Pressure↗