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Biomedical subjects

E A Kulik

Publications and source records attributed to E A Kulik.

6 recordsLinked to original sources
PubMed1995

Simple method for platelet counting.

A method is proposed for counting the number of adhered platelets based on the determination of lactate dehydrogenase activity in bulk after lysis of adhered platelets. This method was compared with the widely used radioisotope labelling technique. It was concluded that the present lactate dehydrogenase method is effective in counting the adhered platelets, as no significant difference was found between the readings of two methods when commercial polymers and glass were used as samples.

Biocompatible Materials↗
PubMed1993

Trypsin immobilization on to polymer surface through grafted layer and its reaction with inhibitors.

Trypsin was covalently immobilized and physically adsorbed on to the surface of poly(ethylene terephthalate) fibres using poly(acrylic acid) (PAAc) chains grafted on to the ozonized fibres. The covalent immobilization was accomplished through amide formation between amino groups of trypsin and carboxyl groups of grafted PAAc chains, with the use of water-soluble carbodiimide. A set of samples with surface concentrations of grafted polymer ranging from 0.03 to 2.5 micrograms/cm2 was used to study the effects of grafted layer on the enzymatic activity of immobilized trypsin and its inhibition by trypsin inhibitors of different molecular sizes. The amount of immobilized trypsin increased linearly with an increase in graft yield of fibres, but the activity of immobilized enzyme reached saturation at a certain graft yield, probably because of diffusion limitation for the transport of enzyme substrate molecules into the grafted PAAc layer. The reduction of inhibition with an increase in graft yield and in molecular weight of inhibitors was attributed to enhancement of steric hindrance and enzyme inactivation in the dense grafted layer. We also found that the adsorbed trypsin was inhibited more easily than the covalently immobilized at any concentration of the grafted PAAc and for any type of inhibitor used.

Acrylic Resins↗
PubMed1991

The heterogeneity of protein/surface interactions and structural alterations of adsorbed albumin and immunoglobulin G.

The theoretical model is developed for the reversible and irreversible protein adsorption in kinetic regime by assuming the continuous energetical heterogeneity for protein/surface interaction and the possibility of structural alterations of adsorbed molecules. The simplest rectangular distributions of adsorption centers in energy of activation are used to explain the logarithmic kinetics of IgG and human serum albumin (HSA) adsorption on a quartz surface. To explain the Freindlich character of HSA adsorption onto a precoated surface, the exponential distributions of adsorption centers in energy of activation are used. A competitive analysis of some of the approaches allowed for the energetical heterogeneity of protein/surface interaction is made. The possibility of lateral electrostatic repulsion to form the logarithmic kinetics of HSA adsorption is checked experimentally. The influence of the temperature on HSA adsorption onto quartz is discussed also.

Adsorption↗
PubMedDate not supplied

[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↗
PubMedDate not supplied

Analysis of albumin deposits on hydroxylated siloxane films. Implications for surface treatment of medical devices.

The authors have developed methods to enhance albumin binding to modified silicone rubber (SR) films. An intermediate bifunctional coupling agent, polyvinylmethyl siloxane-comethyl-1-ethanol siloxane (PVMS-CO-MES), is prepared from a cyclic tetramer, vinyl-methyl siloxane, by an oxymercuration-demercuration reaction, and cross-linked to silicone rubber under mild peroxide catalytic conditions. Free mercury on the surface was obtained under many reaction conditions and is shown to materially enhance 125I-labeled albumin binding. The mechanism most likely occurs via disulfide bond breakage, protein denaturation, and aggregation. The possible role of iodine-mercury bonds, an artefactual source, is ruled out with the aid of total internal reflectance-fluorescence measurements of the albumin adsorption rate constant. Although in situ albumin aggregation via disulfide bond breakage is a potentially attractive method for biocompatible protein gel formation, the toxicity of mercury makes the current method unfit for clinical practice.

Adsorption↗