[Energy heterogeneity of solid surfaces during interaction with protein molecules].
Explore the source record for details and available documents.
Adsorption↗
Biomedical subjects
V I Sevast'ianov
Publications and source records attributed to V I Sevast'ianov.
[Structural and chemical transformations of heat-processed polyacrylonitrile fibers and characteristic parameters of their interactions with thrombocytes and plasma proteins].
A suitable for analysis of the effect of structural and chemical changes on haemocompatibility of polymers is polyacrylonitrilics (PNA), which, depending on the thermo-processing (temperature, medium), make a number of materials, differing in structure and properties. A comparative analysis of physical and chemical initial properties as well as of thermically processed PNA fibres was made. By the methods of radioisotope and of fluoroscent spectroscopy the kinetics of early stages of adsorption of plasma albumine (AS) and of plasma fibrinogen (FG), the kinetics of desorption of pre-adsorbed plasma albumine in a model solution, and thrombocyte adhesion of the PNA surface were studied. The extreme nature of the irreversability degree in albumine and fibrinogen adsorption, the effective coefficients of the albumine desorption speed, and the number of bound thrombocytes at the temperature increase in thermal processing were found, and better quantitative criteria of haemocompatibility in vitro for PNA, processed thermally in the air. The achieved results can be explained by occurrence of, in a number of studied PNA fibres, an optimum ratio of the dispertion and polar superficial surrounding energy.
Absorption↗
[Activation of the complement system during hemodialysis].
One of the adverse effects of haemodialysis is activation of the complement system occurring at the contact of blood with the dialyser membrane. In vitro conditions it was found by means of a modified method of registering haemolitic complement activity pre- and post-incubation with the membrane that the activation of complement in a given blood donor depends both on the inherent complement reactivity and on the surface physico-chemical qualities. The contribution of each component was estimated by means of the coefficient of spontaneous speed (kspont) and of induced speed (kind) of complement activation. The comparison of the results of the complement system activation in vivo (in 9 dialysed patients) with the in vitro results made it possible to use the designed kinetic model in prognostication of the complement system of a given patient subjected to haemodialysis.
Cellophane↗
[Evaluation of the biocompatibility of intraocular lenses of different materials using a tissue culture method].
Explore the source record for details and available documents.
Animals↗
The activation of the complement system by polymer materials and their blood compatibility.
The activation of the complement system by polymer materials and their blood compatibility. One of the negative effects of the clinical application of various blood-containing biomedical devices is the activation of the complement system induced by a foreign surface. A method of determining the hemolytic activity of human serum complement before and after contact with polymers was chosen in order to elucidate the relationship between polymer surface types and the degree of complement activation. The complement activation of each donor proved to depend both on his own complement reactivity and the type of polymer surface. The role played by each constituent was estimated using the rate constants for spontaneous (ksp) and induced (kind) complement activation. The negative correlation (-0,88, p less than 0,001) between the degree of irreversible adsorption of 131I-serum albumin and relative kind was determined. Thus, we propose the use of kind for the criterion of conformational alterations of protein macromolecules induced by the adsorption/desorption processes on blood/surface interface, leading to complement activation.
Adsorption↗
[Comparative effectiveness of the use of hematological methods to analyze the procoagulant activity of biological materials].
Whether clinical hematological methods by employing two parameters: (plasma recalcification time (PRT) and activated partial thromboplastin time (ACTT) can be used to examine the procoagulant activity of the surface of biological materials was comparatively studied. The method PRT was shown to be sensitive and reproducible while ACTT failed to significantly record differences in the procoagulant activities of various materials. The authors chose the optimal protocol for evaluating the blood compatibility of biological materials: the surface area/plasma volume ratio is more than 150 cm2/ml, the incubation time of samples is no less than 180 sec at 37 degrees C and continuous mixing.
Biocompatible Materials↗
[Mathematical processing of human platelet distribution according to size for determination of cell heterogeneity].
The paper proposes a method for mathematical treatment of the distribution of human platelets by sizes to detect the heterogeneity of cell populations. Its use allowed the authors to identify three platelet populations that have different parameters of size distribution. The proposed method opens additional vistas for analyzing the heterogeneity of platelet populations without sophisticating experimental techniques.
Adult↗
[Competitive adsorption of human fibrinogen on an amorphic quartz surface].
The kinetics of adsorption of fibrinogen on the surface of amorphous quartz from binary solutions containing human serum albumin and gamma-globulin was studied by the method of fluorescence of total internal reflection. A model of energetically nonhomogeneous interactions in the surface/protein system was used to explain the mechanism of competitive adsorption of proteins.
Adsorption↗
[Interaction of heparin with amino group-containing materials].
The influence of the glass surface immobilized aminogroups nature and the experiments conditions on the interactions between heparin and aminogroups containing surface was studied using total internal reflections fluorescence. It was shown, that the nature of the terminating aminogroup, but not its mobility or the amount of the aminogroups in the main chain, is the major factor influencing the heparin adsorbtion from individual solution. Both the nature of terminating aminogroup and its mobility determine heparin adsorption on the aminogroups containing surfaces from the blood plasma proteins containing solution. Heparin irreversibly adsorbed from individual solution is not replaced by blood plasma proteins. The tertiary aminogroups containing surface adsorbs maximal quantity of the heparin.
Adsorption↗
[Photovoltaic effect in pigment films in contact with an electrolytes. V. Theory of the Becquerel photovoltaic effect in porous films of phthalocyanine].
In accordance with literature and our experimental data a theoretical analysis of the model system metal-porous film of the pigment-electrolyte was carried out at stationary illumination in the regimes of photocurrent and photopotential. The main properties and positions of the model are supported experimentally. Specific behaviour of the photovoltaic system considered resides in the discovered dependence of the transfer mechanism on the value of catode potential of the electrode.
Electrochemistry↗
[Transdermal delivery of insulin].
A possibility is studied of the transdermal delivery of insulin by using a mixture of synthetic analogues of phosphoglycerides (SAP), as a potential activator of hormone diffusion, through the skin. Experimentally in vitro, it was proven that the diffusion of insulin through the skin of two types of transdermal therapeutic form (TTF)--matrix-type and matrix-hydrogel-type--is possible only in presence of activator SAP-M-99. The detected optimal composition of insulin matrix TTF with the area of 40 sq cm enabled a trandermal hormone diffusion speed of 0.26 UNITS/h, which is compatible with the secretion of insulin by the pancreas of an adult (0.25-1.5 UNITS/h). A change-over for the matrix-hydrogel system of insulin delivery based on a 40 sq cm collagenous sponge enabled to increase the insulin diffusion up to 0.54 UNITS/h.
Adhesives↗
[A comparative analysis of the two approaches to the evaluation of thrombogenic qualities of the biomaterials in vitro].
The paper contains an analysis of thrombogeneticity of biomaterials in vitro with regard for the changing time of recalcification of the platelet-free and platelet-related human blood plasma after incubation with a studied sample. Two sizeless thrombogeneticity parameters are suggested for describing the thrombogeneticity of studied biomaterials irrespective of a incubation-medium composition. It was demonstrated by the example of glass granules, which were modified by various immobilized functional groups, that the measuring of re-calcification time performed after samples' incubation secures a more objective assessment of platelet-resistant properties of materials. The relative index of thrombogeneticity of biomaterials (with the above glass granules being the controls), unlike the standardized parameter, opens up the possibility to study comparatively the activating action exerted on the coagulating and anti-coagulating blood systems of the studied samples, which differ by the ratios of their surface squares to the incubation-medium volume.
Humans↗
[A comparative study of the dynamics of deep burns healing in using medullary allogenic fibroblast-like mesenchymal stem cells from bone marrow immobilized on biodegrading membranes or taken from cultural plastic].
Transplantation of suspention of allogenic fibroblast-like mesenchymal stem cells (AFMSC) of the bone marrow and AFMSC immobilized on the biodegradable membrane (BM) stimulates healing of deep burn wounds compared to control (without cell transplantation) because these cells produce biologically active substances into the wound. AFMSC immobilized on BM activate repair processes in the wounds earlier. This may be due to their higher functional activity created in the monolayer by adequate intercellular interactions. To avoid complications caused by low diffuse properties of BM (protein precipitation), BM should be removed from the surface of the burn wound maximum 3 days after its application.
Animals↗
[Adsorption of human serum albumin on the original and albuminized surface of quartz].
The method of TIRF is used for obtaining kinetic curves of HSA adsorption on coated and uncoated silica surfaces. Using the model of energetic heterogeneous surface an analysis of positive effect of passivation as a result of transformation of energetic heterogeneity of quartz surfaces from rectangular to exponential is performed.
Humans↗
[A method of chemical stabilization of Bionix heart valve prostheses].
Explore the source record for details and available documents.
Animals↗
[Methodology of choosing blood-compatible biomaterials in vitro for artificial organs].
Explore the source record for details and available documents.
Artificial Organs↗
[The effect of silicone resin for medical use on the balance of calcium fractions in human blood serum].
Influence of polymeric material upon the character of formation of ion calcium complexes in the blood serum of man was demonstrated and described by following parameters: quantity of binding sites, equilibrium constant for association and Hill's coefficient. These indexes were proposed to be used as evaluation criterion of calcinosis predisposition in articles used for artificial organs.
Adult↗
[A method of evaluating the degree of activation of the complement system in patients during hemodialysis].
A quantitative criterion of the activation of the patient's complement during hemodialysis has been worked out on the basis of the proposed mathematical model. It has been shown that the activation of the complement system observed during hemodialysis and the negative clinical effects (leukopenia, hypoxia) accompanying it depend both on the membrane properties and the patient's individual response. A possibility has been revealed of using the above criterion for the individual choice of hemodialytic membranes in order to reduce the negative clinical effects connected with the activation of the complement system.
Complement Activation↗