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Biomedical subjects

M V Sergeeva

Publications and source records attributed to M V Sergeeva.

13 recordsLinked to original sources
PubMed2000

Validation of A&D UA-767 device for the self-measurement of blood pressure.

BACKGROUND: The validation of self-measurement devices has been recommended. Automatic monitor A&D UA-767 (A&D Company, Ltd, Tokyo, Japan) is well known and widely used, but not tested according to the Association for Advancement of Medical Instrumentation (AAMI) and British Hypertension Society (BHS) recommendations. OBJECTIVE: To perform a clinical validation for use by adults of the A&D UA-767 device according to the criteria of the AAMI and a modified BHS protocol. METHODS: The test concerned 101 subjects (57 men and 44 women) aged 15-85 years with arm circumferences of 22-39 cm, a systolic blood pressure (SBP) range of 89-206 mmHg, and a diastolic blood pressure (DBP) range of 53-122 mmHg. For each subject, three readings of the UA-767 were compared with simultaneous auscultatory measurements by two trained independent observers who used a mercury manometer and dual stethoscope. The results were graded according to the BHS (1990 and 1993) and AAMI recommendations. RESULTS: Observers showed close agreement, with mean differences of 1.1+/-2.4 mmHg for SBP and -0.7+/-2.0 mmHg for DBP. The proportion of values agreeing to within 5, 10 and 15 mmHg were 93, 100, and 100% for SBP and 97, 100, and 100% for DBP for the two observers. The sphygmomanometer measurements were 132+/-24/79+/-14 mmHg (mean+/-SD). The average difference between the mercury sphygmomanometer and A&D UA-767 readings for SBP and DBP were, respectively, -0.4+/-5.4 and -0.4+/-4. 8 mmHg. The proportion of values agreeing to within 5,10, and 15 mmHg were 82, 94, and 98% for SBP and 80, 95, and 98% for DBP for the observers and device (A/A grade for BHS). CONCLUSIONS: For an adult population, the A&D UA-767 device for the self-measurement of blood pressure satisfied the AAMI criteria, achieved a BHS grade of A/A and can therefore be recommended for monitoring blood pressure in home and clinical conditions by patients with mild-to-moderate arterial hypertension.

Adolescent↗
PubMed1998

The evolution of biotransformation technologies.

Biotransformation is a broad and growing field of biotechnology and encompasses both enzymatic and microbial biocatalysis. Progress has been made in research on the key drivers of biotransformations, including the isolation and characterization of microbes and their enzymes from, and their utilization in, extreme environments, the manipulation, alteration, and augmentation of metabolic pathways, and the use of combinatorial biosynthesis and biocatalytic methodologies for new compound development.

Benzopyrans↗
PubMed1997

Biocatalytic plastics as active and stable materials for biotransformations.

Enzyme-containing polymeric materials have been developed that have high activity and stability in both aqueous and organic media. These biocatalytic plastics, containing alpha-chymotrypsin and subtilisin Carlsberg, can contain up to 50% (w/w) total protein in plastic materials such as poly(methyl methacrylate, styrene, vinyl acetate, and ethyl vinyl ether). The activation achieved in organic solvents by incorporating proteases in plastic matrices allows for the efficient synthesis of peptides, and sugar and nucleoside esters. The marriage of enzyme technology with polymer chemistry opens up an array of unique applications for plastic enzymes, including active and stable biocatalysts in paints, coatings, resins, foams, and beads, as well as membranes, fibers, and tubings.

Acylation↗
PubMed1991

Denaturation capacity: a new quantitative criterion for selection of organic solvents as reaction media in biocatalysis.

The process of reversible denaturation of several proteins (alpha-chymotrypsin, trypsin, laccase, chymotrypsinogen, cytochrome c and myoglobin) by a broad series of organic solvents of different nature was investigated using both our own and literature data, based on the results of kinetic and spectroscopic measurements. In all systems studied, the denaturation proceeded in a threshold manner, i.e. an abrupt change in catalytic and/or spectroscopic properties of dissolved proteins was observed after a certain threshold concentration of the organic solvent had been reached. To account for the observed features of the denaturation process, a thermodynamic model of the reversible protein denaturation by organic solvents was developed, based on the widely accepted notion that an undisturbed water shell around the protein globule is a prerequisite for the retention of the native state of the protein. The quantitative treatment led to the equation relating the threshold concentration of the organic solvent with its physicochemical characteristics, such as hydrophobicity, solvating ability and molecular geometry. This equation described well the experimental data for all proteins tested. Based on the thermodynamic model of protein denaturation, a novel quantitative parameter characterizing the denaturing strength of organic solvents, called the denaturation capacity (DC), was suggested. Different organic solvents, arranged according to their DC values, form the DC scale of organic solvents which permits theoretical prediction of the threshold concentration of any organic solvent for a given protein. The validity of the DC scale for this kind of prediction was verified for all proteins tested and a large number of organic solvents. The experimental data for a few organic solvents, such as formamide and N-methylformamide, did not comply with equations describing the denaturation model. Such solvents form the group of so-called 'bad' solvents; reasons for the occurrence of 'bad' solvents are not yet clear. The DC scale was further extended to include also highly nonpolar solvents, in order to explain the well-known ability of enzymes to retain catalytic activity and stability in biphasic systems of the type water/water-immiscible organic solvent. It was quantitatively demonstrated that this ability is accounted for by the simple fact that nonpolar solvents are not sufficiently soluble in water to reach the inactivation threshold concentration.

Catalysis↗
PubMed1991

[Interconnection of physico-chemical characteristics of organic solvents and their denaturing ability in relation to proteins].

Reversible denaturation of several proteins (alpha-chymotrypsin, trypsin, laccase, chymotrypsinogen, cytochrome c and myoglobin) by a broad series of organic solvents of different nature was studied. The regularities of this process were analyzed, employing both experimental and literary data based on the results of kinetic and spectroscopic measurements. In all the systems under study denaturation proceeded in a threshold manner, i. e., an abrupt change in the catalytic and/or spectroscopic properties of the dissolved proteins was observed after a certain threshold concentration of the organic solvent had been reached. To account for the observed features of the denaturation process, a thermodynamic model of reversible protein denaturation by organic solvents was proposed. This model is based on the widely accepted viewpoint that the undisturbed water shell around the protein globule is necessary for maintaining the dissolved protein in the native state. Quantitative analysis of the model led to an equation establishing a relationship between the threshold concentration of an organic solvent and its physico-chemical characteristics, such as hydrophobicity, solvating ability and molecular geometry. This equation fits well in the experimental data for all the proteins tested. Based on the above thermodynamic model of protein denaturation, a novel quantitative parameter characterizing the denaturing strength of organic solvents (termed as the denaturation capacity or DC) was proposed. Different organic solvents arranged according to their DC values form the DC scale of organic solvents which permits to predict theoretically the threshold concentration of any organic solvent for a given protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Catalytic activity and denaturation of enzymes in water/organic cosolvent mixtures. Alpha-chymotrypsin and laccase in mixed water/alcohol, water/glycol and water/formamide solvents.

The dependence of the catalytic activities of alpha-chymotrypsin and laccase on the concentration of organic cosolvents (alcohols, glycols and formamides) in mixed aqueous media has a pronounced threshold character: it does not change up to a critical concentration of the non-aqueous cosolvents added, yet further increase of the latter (by only a small percentage, by vol.) leads to an abrupt decrease in enzyme activity. Fluorescence studies indicate that the inactivation results from reversible conformational changes (denaturation) of the enzymes. There is a linear correlation between the critical concentration of residual water (at which the enzyme inactivation occurs in a threshold manner) and the hydrophobicity of the organic cosolvents added. A quantitative criterion is suggested for the selection of organic cosolvents to be used for enzymatic reactions in homogeneous water/organic solvent media.

Alcohols↗
PubMedDate not supplied

[Assessment of human health risk due to environmental pollution in the city of Orsk].

The established tense ecological situation in the town of Orsk presents a serious human threat. The use of methods for assessing the risk has allowed the authors to determine the values of carcinogenic and noncarcinogenic risks. Due to the influence of all environments polluted by industrial emissions, the total annual carcinogenic risk is 2.31 cases for the adult population of the town and 0.49 for its children. The greatest carcinogenic risk is associated with arsenic in water and foodstuffs, hexavalent chromium, cadmium, and formaldehyde in the air. The high concentrations of dust, phenol, nitrogen dioxide, and carbon oxide cause a major damage to human health. The established specific values of this risk are of relative significance.

Catchment Area, Health↗
PubMedDate not supplied

[The postradiation radiosensitivity of rats following uniform external irradiation].

In experiments with mongrel male rats exposed to double uniform gamma-irradiation (60Co), the postirradiation radiosensitivity was studied by the criterion of a median lethal dose; clinical and laboratory indices were investigated after preirradiation with doses of 1-5 Gy. A function was proposed to link the dynamics of the postirradiation radiosensitivity of rats to the proliferative activity of bone marrow and its total cellularity.

Animals↗
PubMedDate not supplied

[The postradiation radiosensitivity of rats following partial external irradiation of the abdominal area].

After double partial X irradiation of abdomen the postirradiation radiosensitivity of mongrel male rats was studied by the criterion of a median lethal dose; clinical and laboratory parameters were investigated after preirradiation with 4.6 and 8 Gy. A function is proposed linking the dynamics of the postirradiation radiosensitivity of rats with the proliferative activity of small intestine and its total cellularity.

Abdomen↗