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Biomedical subjects

S V Novikov

Publications and source records attributed to S V Novikov.

17 recordsLinked to original sources
PubMed2002

Characterization of nitride thin films by electron backscatter diffraction.

Thin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light-emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90 degrees rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tiltedby 13 +/- 1 degrees towards [1010]GaN), where the tilt is due to the inclination of the sapphire substrate (cut off-axis by 10 degrees from (0001)sapphire towards (1010)sapphire). We compare EBSD patterns obtained from As-doped GaN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) with low and high As4 flux, respectively. Higher As4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.

Journal Article↗
PubMed2000

Anomalous scaling of a passive scalar in the presence of strong anisotropy.

Field theoretic renormalization group and the operator product expansion are applied to a model of a passive scalar quantity straight theta(t,x), advected by the Gaussian strongly anisotropic velocity field with the covariance infinity delta(t-t('))/x-x(')/(epsilon). Inertial-range anomalous scaling behavior is established, and explicit asymptotic expressions for the structure functions S(n)(r) identical with<[straight theta(t,x+r)-straight theta(t,x)](n)> are obtained. They are represented by superpositions of power laws; the corresponding anomalous exponents, which depend explicitly on the anisotropy parameters, are calculated to the first order in epsilon in any space dimension d. In the limit of vanishing anisotropy, the exponents are associated with tensor composite operators built of the scalar gradients, and exhibit a kind of hierarchy related to the degree of anisotropy: the less is the rank, the less is the dimension and, consequently, the more important is the contribution to the inertial-range behavior. The leading terms of the even (odd) structure functions are given by the scalar (vector) operators. For the finite anisotropy, the exponents cannot be associated with individual operators (which are essentially "mixed" in renormalization), but the aforementioned hierarchy survives for all the cases studied. The second-order structure function S2 is studied in more detail using the renormalization group and zero-mode techniques; the corresponding exponents and amplitudes are calculated within the perturbation theories in epsilon, 1/d, and in the anisotropy parameters. If the anisotropy of the velocity is strong enough, the skewness factor S(3)/S(3/2)(2) increases going down towards the depth of the inertial range; the higher-order odd ratios increase even if the anisotropy is weak.

Journal Article↗
PubMed1999

[The efficacy of flonivin BS in the treatment of intestinal dysbacteriosis].

The paper presents results of intestinal dysbacteriosis (ID) treatment with flonivin in 25 patients. The diagnosis was made clinically and bacteriologically (fecal examinations). Flonivin BS proved to be an effective biological preparation for management of ID stage I and II. It is composed of bacteria which do not conflict with macroorganism, contribute to normalisation of intestinal biocenosis, is especially beneficial in ID induced by long-term administration of antibiotics.

Adolescent↗
PubMed1998

Characterization of angiotensin-(1-7) in the urine of normal and essential hypertensive subjects.

A total of 31 healthy volunteers [39 +/- 7 (SD) years] and 18 untreated essential hypertensive subjects [43 +/- 9 years] collected urine for 24 h after a physical examination and laboratory tests. Radioimmunoassay measurements of angiotensin-(1-7) [Ang-(1-7)] in urine and plasma were done as described previously. Sitting systolic and diastolic blood pressures (+/- SD) averaged 118 +/- 11/74 +/- 7 mm Hg and 146 +/- 16/96 +/- 8 mm Hg in normal and essential hypertensive subjects, respectively (P < .001), whereas 24 h urinary volume was not different in normal and essential hypertensive subjects (P > .05). The concentration of Ang-(1-7) in the urine of normal subjects averaged 62.6 +/- 22.6 pmol/L corresponding to a urinary excretion rate of 98.9 +/- 44.7 pmol/24 h. Concurrent measurements of plasma Ang-(1-7) showed that the content of Ang-(1-7) in urine was 2.5-fold higher than that measured in the plasma. In contrast, untreated essential hypertensive subjects had lower concentrations and 24 h urinary excretion rates of Ang-(1-7) averaging 39.4 +/- 18.0 pmol/L and 60.2 +/- 14.6 pmol/24 h, respectively, (P < .001). Differences in the excretory rate of Ang-(1-7) between normal volunteers and essential hypertensive subjects were not modified by normalization of the data by urinary creatinine excretion rates. Urinary concentrations of Ang-(1-7) correlated inversely with systolic, diastolic and mean arterial pressures (r = -0.48, P < .001). Both urinary Ang-(1-7) [odds ratio of 0.92 (95% CI: 0.88-0.97)] and age were independent predictors of systolic blood pressure. These studies demonstrated the presence of Ang-(1-7) in urine and the existence of reduced levels of the heptapeptide in individuals with untreated essential hypertension. The relatively higher concentrations of Ang-(1-7) in urine compared to plasma agrees with data that showed that Ang-(1-7) may contribute to the regulation of blood pressure. The inverse association between Ang-(1-7) and arterial pressure provides a potential marker for the characterization of forms of essential hypertension associated with reduced production or activity of vasodilator hormones.

Adult↗
PubMed1996

Benefits of adherence to anti-hypertensive drug therapy.

Long-term adherence or compliance with anti-hypertensive drug therapy is poor. It has been estimated that within the first year of treatment 16-50% of hypertensives discontinue their anti-hypertensive medications. Even among those who remain on therapy long term, missed medication doses are common. Epidemiological studies have shown that drug-treated hypertensives have higher blood pressures than age-, gender- and body mass index-matched normotensives. In addition, drug-treated hypertensive men and women who achieve blood pressure normalization are less likely to die over a 9.5-year period than those whose blood pressure remains elevated while taking anti-hypertensive drugs. Thus, one reason for less than optimal reduction of blood pressure-related cardiovascular-renal risk in drug-treated hypertensives is inadequate blood pressure lowering. Quantifiable excess risk has been documented even in the short term ( < 1 year) after interruption or discontinuation of anti-hypertensive medications as total healthcare costs are higher, mostly because of higher hospitalization rates. Data from the Treatment of Mild Hypertension Study (TOMHS) are relevant to long-term adherence to various anti-hypertensive drug monotherapies. At 48 months, 82.5% and 77.8% of participants remained on amlodipine and acebutolol, respectively (both P < 0.01 compared with placebo). However, only 67.5%, 66.1% and 68.1%, respectively, of chlorthalidone, doxazosin and enalapril participants remained on these drugs as monotherapy at 48 months. Differential adherence to long-term anti-hypertensive drug therapy could translate into a greater risk of blood pressure-related complications and higher overall healthcare expenditures. Strategies to minimize the deleterious impact of therapeutic non-adherence with anti-hypertensive medications as well as the clinical and cost implications of the TOMHS data will be discussed.

Antihypertensive Agents↗
PubMed1995

[An experimental study of the tissue compatibility of titanium implants coated with hydroxyapatite and aluminum oxide by plasma spraying].

The reaction of bone tissue to implantation of cylindric titanium implants sprayed with hydroxyapatite and aluminum oxide was studied. The coating was characterized by a high biological histocompatibility. The elements of cellular reactions specific for foreign bodies were absent, this permitting us to refer such coating to bioactive materials. The strength of fixation in the bone was compatible to the strength of osseous tissue adjacent to bone tissue implant. The coating may be used in oral implantology, traumatology, and orthodontics.

Aluminum Oxide↗
PubMed1994

Blood pressure monitor-induced petechiae and ecchymoses.

A case is presented of a diabetic, hypertensive, female patient who suffers from a bleeding complication from application of an ambulatory blood pressure monitor. A recent literature search is referred to and practitioners are cautioned against this adverse reaction.

Blood Pressure Monitors↗
PubMed1994

[Diagnostic value of investigating exhaled air condensate in lung cancer].

Parameters of lipid peroxidation and the levels of calcium ions in blood plasma and exhaled air condensate (EAC) were studied in 47 patients with lung cancer. The changes in EAC turned out to be more specific than those of blood plasma. The level of lipoperoxidation in condensate in cancer patients was lower than in healthy subjects. However, calcium cations concentrations in both blood and EAC were relatively higher, the latter difference being significant. The investigation pointed to a greater diagnostic value of EAC measurements, as compared with blood plasma, in lung cancer patients.

Adult↗
PubMed1992

[The development of occupational hearing loss under the influence of pulsed noise].

The deafness was studied in workers engaged into the weaving and the blacksmithing. Both groups of workers were exposed to the noise dose of 109 dB estimated according to Robinson's formula. Processing of received data in diminished hearing revealed the reliable difference between the studies groups both in quantity of the cochlear neuritis and the grade of the hearing failure. Slight hearing failure predominated in the weavers' group whereas the moderate and severe forms appeared in the blacksmiths. Analysis revealed the positive correlation between the overall noise dose and diminished hearing in all studied groups concerning high and voice frequencies. The impulsive noise appeared to be more aggressive than the constant one.

Adult↗
PubMed1991

[Evaluation of the hemodynamic effects of the long-acting peripheral vasodilator flosequinan in patients with chronic heart failure].

The hemodynamic effects of the peripheral vasodilator flosequinan, 100 mg/day, were evaluated in 20 patients with Stage IIA-IIB (the Lang-Strazhesko-Vasilenko classification) heart failure. The doses of digoxin and diuretics were found to be stable. The right cardiac cavities and pulmonary artery were catheterized by Swan-Ganz balloon catheters. The agent was demonstrated to produced profound effects showing decreased pre- and afterload when given both in a single dose or in course therapy.

Adult↗
PubMed1990

[The functional characteristics of the eye vessels in glaucoma and suspect glaucoma].

The paper analyses results after examination of the functional state of eye vessels in 92 patients (117 eyes) with initial stage of glaucoma and 44 persons (55 eyes) with suspected glaucoma. A control group included 31 patients (41 eyes) without any eye pathology. For assessment of the functional state of eye vessels, cryorheographic test was used. Main types and variants of neurovascular reactions of the eye were determined. Reduced vascular tonus was recorded in most of the subjects. Glaucomatous, patients showed predominantly organic changes in the vascular bed of the eye. In persons with suspected glaucoma, the incidence of functional and organic changes of the vessels was approximately the same. In healthy persons, functional changes were observed more frequently. A conclusion is made that the functional state of the vascular bed of the eye should be considered when prescribing medicamentous treatment for glaucomatous patients.

Aged↗
PubMed1987

[Use of peripheral vasodilators with different mechanisms of action in treating heart failure patients].

The efficacy of peripheral vasodilators with various mechanisms of action was studied in 26 patents with congestive heart failure, left ventricular dilatation and valvular regurgitation. An acute pharmacological test using prazosin was used in all the patients, 20 of them were given a 15-day course of prazosin therapy, 19 patients received a prolonged course of prazosin therapy (over 3 mos.), 15 patients were given a 15-day course with a combination of isosorbide dinitrate and hydralazine. ECG monitoring, catheterization of the right cardiac chambers, thermodilution, and tetrapolar impedance plethysmography were employed. Heart rate, arterial pressure, parameters of cardiac pre- and afterload and pulmonary hemodynamics were studied. Prazosin and isosorbide dinitrate in combination with hydralazine showed a high clinical efficacy in the treatment of patients with congestive heart failure. The improvement of clinical symptomatology was accompanied by considerable positive shifts of the central and peripheral hemodynamics. No considerable differences in the efficacy of prazosin and the combination of isosorbide dinitrate with hydralazine were revealed.

Adolescent↗
PubMed1985

[Comparative evaluation of the effectiveness of various peripheral vasodilators in the treatment of cardiac insufficiency].

The efficacy of peripheral vasodilators with different action mechanisms was studied and compared in 96 patients with chronic circulatory failure, stages IIB-III, of different genesis (rheumatic fever, congestive cardiomyopathy, postinfarction cardiosclerosis). Isosorbide dinitrate was used in 16 patients, nitroglycerin in 36, pratsiol in 24, and captopryl in 20 patients. Monitoring of the ECG, heart rate, respiratory rate and arterial blood pressure as well as catheterization of the right heart and tetrapolar impedance plethysmography were performed. The parameters of the heart pre- and afterload, pulmonary hemodynamics as well as those characterizing myocardial contractility were measured. It was established that the successful use of the different vasodilators rests on an adequate determinations of the indications for use. Captopryl is particularly effective in grave circulatory failure associated with a dramatic activation of the renin-angiotensin system. Pratsiol is effective in all the cases of chronic CF, since the tone of the sympathoadrenal system is virtually always high in patients with grave decompensation. Pratsiol was particularly efficacious in chronic CF with mitral or aortal regurgitation.

Administration, Oral↗
PubMedDate not supplied

[Problems of development of a uniform nomenclature of medical goods].

Problems of development of a uniform nomenclature of medical goods are considered. The importance of compliance of the developed uniform nomenclature with numerous existing standards is emphasized. The uniform nomenclature should also be approved by administrative institutions in the field of medicine.

Equipment and Supplies↗
PubMedDate not supplied

[Predictions of occupational noise-induced hearing loss].

Mathematical modelling is attempted to prognosticate occupational hypoacusis by Robinson's formula, 1999 International standard (1990), first-hand experience gained in hearing control in subjects occupationally exposed to noise and domestic expert criteria of hearing loss quantitation. Factors of risk to develop hypoacusis in noisy environment were put to the correlation analysis which showed their pathogenetic significance in the internal ear cochlear affections.

Algorithms↗
PubMedDate not supplied

[Fatty acid composition of blood plasma lipids and erythrocytes in lung cancer patients].

The fatty acid spectrum of blood plasma and erythrocytic membrane lipids were studied in 47 patients with lung cancer. The changes in the plasma and erythrocyte fatty acid composition were found to be identical irrespective of the clinical cancer form. In blood plasma of these patients with lung cancer, a decrease in the level of polyunsaturated fatty acids was observed with the normal levels of arachidonic acid and the proportion of monoenic fatty acids was increased. Changes in the lipid composition of erythrocyte membranes were characterized by less pronounced polyunsaturated fatty acid deficiency than that in the plasma, which accompanied by decreases in arachidonic acid levels. The appearance of significant levels of nonadecanoic acid also seems striking.

Adult↗