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Biomedical subjects

L I Valuev

Publications and source records attributed to L I Valuev.

At least 19 recordsLinked to original sources
PubMed2005

[To the question of the possibility of oral insulin administration].

The influence of oral insulin upon carbohydrate exchange in healthy volunteers was evaluated. One of the two forms of insulin used in the study was insulin, immobilized in a volume of polyacrylamide gel, modified by ovomucoid (proteolytic enzyme inhibitor), isolated from duck eggs; the other form was enteric-coated tablets bases on hydrogel substance. The oral administration of the hydrogel substance or the tablets resulted in the fall of blood glucose concentration by 34.9 +/- 4.4% and 28.6 +/- 6.9%, respectively. The maximal effect of the hydrogel substance and the tablets was observed at the 90th and the 180th minutes.

Administration, Oral↗
PubMed2002

Mucoadhesive polymers with immobilized proteinase inhibitors for oral administration of protein drugs.

A new approach to overcome the degradation of protein drugs by proteolytic enzymes and their targeting to the blood through the digestive apparatus was developed. The approach is based on the immobilization of drugs into the polymeric hydrogel containing glycoprotein--ovomucoid from duck egg whites. This glycoprotein inhibits the activity of proteolytic enzymes and acts as a biospecific ligand to lectins on the walls of the gastrointestinal tract.

Administration, Oral↗
PubMed1996

[Synthesis and study of immobilized insulin].

Conjugates of insulin with duck egg-white ovomucoid and soybean trypsin inhibitor were synthesized. The conjugates are highly stable to alpha-chymotrypsin treatment. Oral administration of insulin-ovomucoid conjugates in rabbits significantly lowered blood glucose level unlike administration of insulin-soybean trypsin conjugate.

Animals↗
PubMed1993

Biospecific haemosorbents based on proteinase inhibitor. I. Synthesis and properties.

Sorbents for the removal of proteolytic enzymes from biological fluids were synthesized by immobilization of proteinase inhibitor, ovomucoid from duck egg white, in polymeric hydrogel matrix. The immobilization of the protein inhibitor modified by acryloyl chloride occurs during copolymerization of the unsaturated derivative of inhibitor with hydrophilic monomer and crosslinking agent. It was shown that the sorbent obtained possesses a high affinity for proteinases and is haemocompatible. The use of the haemosorbent for eliminating excess activated proteinase from blood is proposed.

Animals↗
PubMed1993

Covalent immobilization of microorganisms in polymeric hydrogels.

A method of covalent immobilization of microorganisms (marine luminescent bacteria and yeast) in polymeric hydrogels is described. It is shown that cell immobilization leads to the creation of materials having properties of both synthetic polymers and physiologically active systems. Application of systems containing covalent immobilized yeast and photobacteria in biotechnological and other processes is proposed.

Acetates↗
PubMed1988

[Interaction of ovomucoid from duck egg white with serine proteinases].

The interaction of highly purified duck egg white ovomucoid with trypsin and chymotrypsin was studied. It was found that the ovomucoid molecule contains two equally effective trypsin-binding sites which, in their turn, comprise lysine residues and one independent chymotrypsin-binding site. The values of inhibition constants were determined and the changes in free energy, enthalpy and entropy during the ovomucoid interaction with trypsin and chymotrypsin were established. It was shown that the inhibitor affinity for the enzymes does not change at low degrees of free amino groups modification.

Amino Acids↗
PubMed1983

On the mechanism of enhanced thromboresistance of polymeric materials in the presence of heparin.

Polymeric materials with covalently immobilized heparin were shown to display enhanced thromboresistance in vitro and in vivo experiments. This property of heparin-containing polymers is due to the specific effect of immobilized heparin for every step of interaction of a polymer with blood. The presence of heparin substantially changes the character of adsorbed proteins on a polymer surface and the number of adhered platelets. Thromboresistance enhancement is largely carried out by the interaction of immobilized heparin with plasma proteins which is accompanied by the decrease in total blood coagulant activity, by the decrease in fibrinogen, prothrombin and thrombin concentrations, and by the supression of fibrinstabilizing factor activity. The free heparin content in blood is not changed. It was found that immobilized heparin forms complexes with fibrinogen, thrombin and plasmin that produce lytic action on unstabilized fibrin.

Adsorption↗
PubMed1982

On the interaction of heparin-containing polymers with plasma proteins and blood.

In vitro exper iments showed that polymeric hydrogels containing covalently immobilized heparin affect the parameters of blood clotting system. This is not accounted for by the elution of heparin into the surrounding medium and this property of heparin-containing polymers is caused by specific interaction of immobilized heparin with plasma proteins. By the methods of coagulograms and thromboelastography it was revealed that the decrease of total blood anticoagulant activity takes place due to the decrease in blood of fibrinogen, prothrombin and thrombin content and the suppression of fibrin stabilizing factor activity. Free heparin content in blood was left unaffected. It was found that plasma proteins permeate the hydrophilic polymer matrix and interact with immobilized heparin. Binding strength for immobilized heparin is decreased in the array fibrinogen congruent to thrombin much greater than plasmin greater than serum albumin. Complexes of immobilized heparin with fibrinogen, thrombin and plasmin display lytic action towards unstabilized fibrin.

Animals↗
PubMed1981

[Reaction between blood and heparin immobilized on synthetic polymers].

The influence of heparin covalent immobilization on its biological functions was studied. In-vivo experiments with prosthetic vascular devices made from polyethyleneterephthalate modified with heparin demonstrated that after 6 months of implantation to dogs the prostheses maintain their functions without thrombus formation. Thromboelastography and coagulograms showed that the decrease in the overall coagulant activity of the blood and changes in the most parameters of the coagulation system take place as a result of blood contact with heparin-containing polymers. In the animal body the changes observed were found to be rapidly compensated for. On studying the interaction of immobilized heparin with plasma proteins it was discovered that fibrinogen, thrombin and fibrinolysin are actively bound by immobilized heparin, with the resulting products being active in lysis of non-stabilized fibrin.

Animals↗
PubMedDate not supplied

Chemical modification of polymers with physiologically active species using water-soluble carbodiimides.

The covalent immobilization of some proteins (ovomucoid from duck egg white, human serum albumin, aldolase and thiroglobulin) on the surface of polyethylene grafted with polyacrylic acid has been studied. Water-soluble carbodiimide was (1-ethyl-3-(3-dimethylaminopropyl carbodiimide) used as a condensing agent. It was shown that three different reactions can occur in the reaction mixture during immobilization: the reaction between carboxy groups of graft copolymer and amino groups of protein (the immobilization reaction itself) and reactions between carboxy and amino groups of protein molecules (reactions of intra- and intermolecular cross-linking). The reaction of intramolecular cross-linking leads to a decrease in the physiological activity of the immobilized substance, while other reactions do not affect it. The preliminary activation of this surface by carbodiimide before the modification allows to maintain the activity after immobilization on the insoluble surfaces.

Acrylic Resins↗
PubMedDate not supplied

[Inhibitors of proteolytic enzymes in the treatment of diabetes mellitus].

A new approach to overcome the degradation of insulin by proteolytic enzymes and its targeting to the blood through the digestive apparatus was developed. The approach is based on the immobilization of insulin into the polymeric hydrogel which is modified by ovomucoid--glycoprotein, inhibitor of proteolytic enzymes. Oral administration of this system to rabbits and rats, (in contrast to the hydrogels modified by proteolytic enzymes inhibitors without polysaccharide part), statistically significantly lowered blood glucose level.

Animals↗
PubMedDate not supplied

[Stability of immobilized insulin preparation at various pH].

The stability of polyacrylamide hydrogel, modified by ovomucoid with immobilized insulin was studied at different pH of external medium. At 3.8 < pH < 5.5 insulin binds to the gel, due to electrostatic interaction between ovomucoid and insulin molecules.

Acrylic Resins↗
PubMedDate not supplied

[Polymeric systems with antithrombin activity for thermally activated targeting].

Copolymers of N,N-diethylacrylamide and N-acryloylphthalimide with lower critical solution temperature (LCST) were synthesized by radical copolymerization. Polymeric systems with antithrombin activity and LCST were prepared via a reaction of amino groups of hirudin with phthalimide groups of the copolymers. On increasing hirudin content, LCST of the polymeric systems increased. The antithrombin activity of polymeric systems obtained by hirudin immobilization on copolymer carriers was inversely related to the content of the copolymer, amounting to 6% of the activity of native hirudin.

Acrylamides↗
PubMedDate not supplied

[Interaction of ovomucoid from duck egg proteins with aldehydes-dextrans].

The interaction of ovomucoid proteinase inhibitor prepared from duck egg white with a dextran of a molecular weight of 70,000 preliminary treated with potassium periodate. Irrespective of the number of the sites of the ovomucoid binding to aldehyde-dextran the anti-chymotryptic activity is equal to that of the native inhibitor, while the antitryptic activity decreases proportionally to the number of ovomucoid amino groups involved in the reaction with dextran. When a few ovomucoid molecules are immobilized on the polysaccharide macromolecule the perturbing effect of the protein-protein interactions is minimal, as the rigid polymeric chain prevents from the formation of associates of proteins immobilized on this backbone.

Aldehydes↗
PubMedDate not supplied

[New prospects for a method of biospecific chromatography].

The polyacrylamide hydrogels with covalently immobilized ovomucoid from the duck's egg white were synthesized by radical copolymerization. These hydrogels can defend the immobilized insulin against the action of proteolytic enzymes. Biospecific interaction of the polysaccharide component of ovomucoid with lectins leads to the targeting transport of the hydrogel particles onto the small intestine wall.

Acrylic Resins↗