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Biomedical subjects

A A Belov

Publications and source records attributed to A A Belov.

At least 19 recordsLinked to original sources
PubMed2002

[24-Hour arterial pressure profile in chronic obstructive lung diseases in combination with arterial hypertension treated with enalapril].

AIM: To evaluate peculiarities and trends in 24-hour arterial pressure (AP) profile and bronchoobstructive syndrome (BOS) in patients with chronic obstructive pulmonary diseases (COPD) and arterial hypertension (AH) on combined treatment including enalapril maleate. MATERIAL AND METHODS: Changes in BOS as shown by clinical data, data of peakflowmetry and external respiration function as well as in AP 24-hour profile according to 24-hour monitoring were studied in 50 patients with exacerbation of bronchial asthma and chronic bronchitis treated for 4 weeks with conventional broncholytic and antiinflammatory modalities, in 28 patients with mild and moderate AH receiving combined therapy including enalapril maleate. RESULTS: In exacerbation of COPD, 24-h AP profile is characterized by high frequency of the curve "non-dipper". Concomitant mild and moderate AH was diagnosed in more than half of the examinees. The addition of enalaprile maleate to the treatment in many cases lowered systolic and diastolic AP, normalized sympathicoadrenal system and 24-hour AP rhythm, reduced dyspnea, improved exercise tolerance, sleep. Good tolerance of the drug was seen in patients with exacerbation of COPD. CONCLUSION: In exacerbation of COPD it is recommended to monitor AP for 24 hours for early detection of AH and initiation of combined treatment with correction of bronchoobstructive syndrome and hemodynamic disorders. As a hypotensive drug, enalapril maleate is adequate in such patients.

Aged↗
PubMed2002

[Types of structural-functional disorders in severe chronic obstructive pulmonary disease].

To differentiate approaches to assessment of treatment and prognosis specificities in a severe course of chronic obstructive pulmonary diseases (COPD), a study was made of 30 patients with long-term COPD. The patients were divided into groups by the severity of respiratory insufficiency which was investigated by saturation of 0(2) and gas composition of arterialized capillary blood, flow-volume curve and bodyplethysmography, ECG, echo-CG. High resolution computed tomography of the lungs was used to evaluate diffuse changes of pulmonary tissue and its morphological rearrangement. Basing on the rhoentgenomorphological picture, most typical variants of pulmonary tissue changes were identified. Comparison with the clinical and laboratory-instrumental data allowed to characterize four structural-functional types which occur in severe COPD. Etiological and pathogenetic features of the above types (the role of smoking, in particular) and their contribution to development of pulmonary hypertension, treatment and prognosis are discussed.

Electrocardiography↗
PubMed2002

[Rheography of extracorporeal circulation: verification of method and calibration of the monitor].

Cardiopulmonary bypass as a reference flow model for impedance cardiography monitoring is described in 34 children during open-heart surgery. Such an approach not only proved the accuracy and precision of impedance cardiac output measurement, but also gave a possibility to make intra-operative calibration of any cardiac output monitor which maintains its accuracy during the post-bypass period.

Adolescent↗
PubMed2001

[Thermodilution and rheography: the coincidence and reproducibility of results].

A comparison of the pulmonary artery thermodilution and tetrapolar impedance cardiography of cardiac output measurements based on 312 dual determinations has shown a good general coincidence, but better reproducibility of the impedance cardiography data and more evident character of the errors and artifacts. The authors' analysis of the mechanisms and causes of such phenomena is based both on their own conclusions and on a wide spectrum of the data of previous investigations.

Adult↗
PubMed1993

[The effect of the antidepressant pyrazidol and its nitro analog on cGMP-dependent phosphodiesterase from the soluble fractions of the human cerebral cortex].

The effects of the antidepressant pyrazidol (pirlindole) and its nitro analog on cGMP-dependent phosphodiesterase from the soluble fraction of human brain cortex have been studied. Pirlindole inhibits the cGMP-induced activity of phosphodiesterase (IC50 = 1585 microM) without influencing the basal activity; its action is noncompetitive in respect of the substrate and the activator. Nitropirlindole is a more potent inhibitor of cGMP-dependent phosphodiesterase (IC50 = 115 microM) competing with the substrate for the catalytic site (K(i) = 70 microM). There is no direct interaction of pirlindole (pyrazidol) and its nitro analog with the cGMP-specific site in phosphodiesterase.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

[Ca2+-calmodulin-activated cyclic nucleotide phosphodiesterase from the soluble fraction of the human brain: Kinetic properties and the effect of the antidepressant pyrazidol and its nitro analog on the enzyme].

The kinetic characteristics of two forms of soluble Ca(2+)-calmodulin-activated phosphodiesterase (PDE I and PDE II) from human brain are presented. Both PDE forms display a higher affinity for cGMP than for cAMP: the differences in the Km values of PDE II for the both cyclic nucleotides are less pronounced. For the both enzyme forms cGMP competitively inhibits cAMP hydrolysis. Activation of PDE I by Ca(2+)-calmodulin is characterized by increasing Vmax without any changes in Km for both substrates. In case of PDE II the Ca(2+)-calmodulin-dependent increase in Vmax is accompanied by decreasing Km for cAMP and cGMP. Pyrazidol and nitropyrazidol inhibit Ca(2+)-calmodulin induced activity with no effect on basal PDE activity. The data obtained exclude competition of the both compounds with the substrate and the activator for the catalytic site and the allosteric Ca(2+)-calmodulin-specific site. It is suggested that the allosteric effect of these compounds on the activity of PDE involves a site in the enzyme which is distinct from the calmodulin-binding site.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1989

[3',5'-cyclic nucleotide phosphodiesterase from human brain].

3':5'-Cyclic nucleotide phosphodiesterase was isolated from human brain and characterized. After the first stage of purification on phenyl-Sepharose, the enzyme activity was stimulated by Ca2+ and micromolar concentrations of cGMP. High pressure liquid chromatography on a DEAE-TSK-3SW column permitted to identify three ranges of enzymatic activity designated as PDE I, PDE II and PDE III. Neither of the three enzymes possessed a high selectivity for cAMP and cGMP substrates. The catalytic activity of PDE I and PDE II increased in the presence of Ca2+-calmodulin (up to 6-fold); the degradation of cAMP was decreased by cGMP. The Ca2+-calmodulin stimulated PDE I and PDE II activity was decreased by W-7. PDE I and PDE II can thus be classified as Ca2+-calmodulin-dependent phosphodiesterases. With cAMP as substrate, the PDE III activity increased in the presence of micromolar concentrations of cGMP (up to 10-fold), Ca2+ and endogenous calmodulin (up to 2-3-fold). No additivity in the effects of saturating concentrations of these compounds on PDE III was observed. Ca2+ did not influence the rate of cGMP hydrolysis catalyzed by PDE III. In comparison with PDE I and PDE II, the inhibition of PDE III was observed at higher concentrations of W-7 and was not limited by the basal level of the enzyme. These results do not provide any evidence in favour of the existence of several forms of the enzyme in the PDE III fraction. The double regulation of PDE III creates some difficulties for its classification.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

[Induction of delayed luminescence of pea photosystem II with genetically changed level of starch in the seeds].

We studied the curves of delayed luminescence induction in leaves of pea plants with mutations affecting the starch branching enzyme (r locus) and ADPG pyrophosphorylase (rb locus). In mutated pants, a 75% reduction of starch content in seeds was observed. The half-decay time of delayed luminescence intensity during induction for double mutants was shown to be longer than for wild type plants.

Luminescence↗
PubMedDate not supplied

[Electron structure of plastoquinone and coupling of electron and proton transport in thylakoids of the higher plants].

The energy dependence on hydrogen position for a system, consisting of plastoquinone (in different redox states) and histidine molecules was studied. The distance between the atoms forming the hydrogen bond, an oxygen of the quinone molecule and a nitrogen of histidine, was supposed to be fixed. It was shown that for neutral quinone the total energy is minimal when the hydrogen is bound to histidine; for reduced quinone, the probability of hydrogen binding to quinone and histidine is approximately equal (so that a hydrogen bond is formed) and on secondary reduction of plastoquinone, the hydrogen binds to it.

Electron Transport↗
PubMedDate not supplied

[Theoretical study of the pulse method for the quenching analysis of photosystem II fluorescence].

The kinetics of photochemical (qQ) and nonphotochemical (qE) fluorescence quenching during induction was studied in terms of the earlier developed theoretical model of photosynthesis. Photochemical and nonphotochemical quenching was calculated from the parameters of fluorescence induction upon simultaneous excitation with continuous light and by high-intensity light pulses by the method used in a PAM fluorometer. It is shown that the fraction of closed reaction centers during the pulse can change in the course of induction. In consequence, even when none of supposed mechanisms of photochemical quenching is taken into account, the value of qE during induction varies and is not equal to zero.

Fluorescence↗
PubMedDate not supplied

[Effect of light of various spectral composition on kinetics of changes in a green leaf resistivity].

The kinetics of changes in the resistance of a green leaf by the action of exciting light was studied. It was shown that the illumination-induced changes in leaf conductance are mainly due to an elevation of temperature caused by the absorption of light energy. Based on the experimental results, the fraction of absorbed light energy converted into heat calculated under assumption that heating of the leaf across the thickness is uniform. It was found that the fraction of absorbed energy converted into heat does not depend on the intensity of radiation in the IR range and increases with decreasing intensity of photosynthetically active radiation. An explanation of the phenomenon is proposed, which is based on that in reality the heating of the leaf across the thickness is nonhomogeneous and this inhomogeneity of heating becomes more pronounced upon photoinduced changes in absorption resulting from a decrease in photosynthetically active radiation. It was shown that nonphotochemical fluorescence quenching does not substantially affect the leaf conductance at intensities of photosynthetically active radiation not higher than 200 Wt/m2.

Electric Conductivity↗