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Biomedical subjects

A N Kuznetsov

Publications and source records attributed to A N Kuznetsov.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Diffusion of a fluorescent probe in egg lecithin multilayers and the effect of a permanent magnetic field].

A method is developed for determining the value of transverse diffusion coefficient through lipid multilayers. Using the absorption kinetics parameters of 1-aniline-8-sulphonate naphthalene (ANS) the value of diffusion coefficient was estimated as Dt = (3 +/- 1). X 10(-12) cm2 s-1 at (22 +/- 0.5) degrees C. The value of Dt was shown to increase under the action of the magnetic field parallel to the multilayer surface; a relative increase of Dt at field 1.3 T is +(40 +/- 15)%.

Diffusion↗
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[Effect of a permanent magnetic field on the formation of lipid bilayers].

Effect of the constant magnetic field (MF) by the induction of 1.1 T on formation kinetics of bilayer lipid membranes (BLM) from egg lecithin in decane was discovered. Under the effect of MF oriented in parallel to the lipid film place the rate of BLM formation decreases, while at its perpendicular orientation it is accelerated. The stationary value of BLM capacity decreases under MF effect at both orientations. The discovered changes in the rate of BLM formation under MF effect seem to be related to the effect of MF on liquid crystalline structure of colour lipid film.

Electric Conductivity↗
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[The effect of ultrahigh frequency electromagnetic fields on the reduction of ferricyanide by human erythrocytes in the presence of methylene blue].

Effect of microwave radiation with the frequency of 1000 +/- 10 MHz and specific absorption rate of 220-580 mV/g on the ferricyanide reduction by human red blood cells in the presence of methylene blue (carrier of oxidation-reduction equivalents through the membrane) was studied at different temperatures in the region of 23-34 degrees C. The temperature dependence of the ferricyanide reduction rate in Arrhenius plots shows two sharp "anomalous" sites with apparently negative activation energy at 26-27 and 29-30 degrees C. Broadness and expression of the "anomalous" sites increased with an increase of the blood storage time. The increase of the ferricyanide reduction rate under microwave irradiation was observed only in the temperature regions corresponding to the "anomalous" sites of the temperature dependence.

Erythrocytes↗
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[Kinetic analysis of the possible effect of a constant magnetic field on the rate of enzymatic reactions].

The simplest scheme of enzymatic reaction (ER) in which the electronic spins of the enzymatic active centre and substrate (S) equal 1/2 is analysed. It is shown that for delta g-mechanism, as well as for the relaxation mechanism of the action of constant magnetic field (MF) on the electronic spin conversion the conversions between singlet and triplet states of the enzyme-substrate complex can be described by monomolecular reactions with definite constants. The dependence of the rate of steady-state ER upon elementary ER constants and upon singlet conversion constants is obtained by the graph method. It is shown that MF changing the singlet conversion constants can influence the rate of ER under definite correlation between elementary constant of ER. In the case of [S] much less than Km (Km--Michaelis constant) the considered ER is in accordance with the recombination reaction of free radicals (RR) by kinetic characteristics, when [S] approximately greater than Km the specific influence of MF on ER with respect to RR is displayed. Under these conditions the action of MF can grow significantly with respect to RR case depending on the correlation between the elementary constants of ER.

Biophysical Phenomena↗
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[Effect of a constant magnetic field on the respiration of human skin during reparative and destructive processes].

Effect of magnetophore applicators constant magnetic field (MACMF) on the functional state of human skin at reparative and destructive processes. It has been found in the investigations carried out during epidermatoplasty under the magnetic field effect on the reparation zone for 10--12 days that MACMF effect is of antihypoxic character and is manifested locally and only on a regenerating tissue. In the experiments on skin grafts exposed to magnetic field for 22--26 hours there was also found antihypoxic direction of MACMF effect expressed in the stabilization of tissue respiration, which points to the weakening of destruction.

Humans↗
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[Systems analysis in medical technology].

Main characteristics of clinical laboratory instruments for biochemical investigations are determined as are the required number of instruments and allocation of the available resources needed at the stage of development. The problem was approached by means of systemic analysis methods based on applying matrix prediction and solving the optimization problem prescribed by the set of inequalities. Calculated values represent actual needs of clinical laboratories, so it became possible to include development of these instruments into the Institute's plan.

Laboratories↗
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[Effect of the constant magnetic field on the chemoluminescence of the skin during its destruction].

A study was carried out of the effect of constant magnetic field of magnitophore applicator ALM-2 (CMFMA) with magnetic induction B on the surface, in the active centre zone--30 MT and gradient B--5 mT/mm on the intensity of peroxidation of lipids in the human skin during its destruction and under hypothermia. Parameters of ultralow chemoluminescence of skin homogenates initiated by bivalent iron ions were considered as intensity indices of lipid peroxidation. It has been shown that skin incubation for 24 hours under CMFMA effect rules out the strengthening of lipid peroxidation, while it takes place at skin incubation under normal conditions.

Cold Temperature↗
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[Influence of magnetic field on hydrogen peroxide decomposition by catalase].

The rate constants of H2O2 decomposition equal to 0.45 X 10(7) M-1S-1 per hem and Michaelis constants higher than 0.3 M were found by gas volume meter and spectrophotometer methods for purified preparations of catalase from bovine liver. Unlike the results obtained earlier the magnetic field with induction 0.65 T and 0.012 T does not affect the constant rate within 3%. It was found with the substrate concentration less than 0.01 M when the classical catalase mechanism was observed and with higher concentration of the substrate up to 0.7 M when the catalase inhibition by H2O2 played an important role.

Animals↗
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[Hydrolysis of globular proteins with trypsin in a strong magnetic field].

To test probable effect of the magnetic field (MF) on the dynamic structure of globular proteins the action of strong MF on proteolysis rate of methemoglobin and serum albumin with trypsin was studied. It has been found that the MF up to 10 T does not affect the proteolysis rate of these proteins and does not effect that of serum albumin with immobilized trypsin. This makes impossible consideration of the effect on the dynamic structure of globular proteins as a mechanism of the MF action on biological systems.

Humans↗
PubMedDate not supplied

[Absence of the effect of magnetic field on dissolving oxygen in aqueous solutions].

To check a number of experimental works the effect of constant magnetic field with induction 0.35 T on dissolving of oxygen in water and in 0.1 n of NaCl was studied. The magnetic field of the indicated value was shown not to affect solubility and the rate of dissolving of oxygen in water and in aqueous solution of electrolyte. These findings well agree with theoretical concepts and make it impossible to consider direct effect of the magnetic field on the molecules of paramagnetic oxygen as one of possible mechanisms of the magnetic field effect on biological systems.

Magnetics↗
PubMedDate not supplied

[Inhibition of respiration of mitochondria by o-phenanthroline in a constant magnetic field].

Preincubation of mitochondria treated with chelator of non-heme ferrum o-phenanthroline (0,067-0,267) for 20 min at 18 degrees C in the constant magnetic field of 330 mT brings about a decrease of the intensity of their uncoupled respiration with NAD-dependent substrates by 15-20% as compared to similar mitochondria preparations without the magnetic field effect. The latter is not realized during conjugated respiration with NAD-dependent substrates at uncoupled respiration with succinate, and in the absence of o-phenanthroline as well.

Animals↗