Biomedical subjects

I L Valuev

Publications and source records attributed to I L Valuev.

10 recordsLinked to original sources

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↗

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

[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↗

PubMedDate not supplied

[Structure and functional properties of temperature-sensitive derivatives of immobilized proteins].

Polydiethylacrylamides (degree of polymerization, 13-470) containing a terminal carboxyl group were obtained by the method of radical polymerization of N,N-diethylacrylamide in the presence of mercaptoacetic acid. In the presence of 1-ethyl-(3,3-dimethylaminopropyl)-carbodiimide, these polymers reacted with ovomucoid to produce its polymeric derivatives. The values of the lower critical mixing temperature of these derivatives and the inhibitory activities of immobilized ovomucoid were determined by the length and amount of polydiethylacrylamide macromolecules bound to the molecule of ovomucoid.

Acrylamides↗

PubMedDate not supplied

[Problems in creating insulin preparations with increased stability against proteolysis].

Chemical methods that accelerate the transport of insulin and other polypeptides across biological membranes and increase their resistance to enzymatic hydrolysis are reviewed. These methods include chemical modification of insulin macromolecules, the use of compounds that increase the permeability of biological membranes or inhibit enzymatic proteolysis, the hormone immobilization in a polymer coat protecting it against the aggressive environment, the incorporation of insulin into liposomes, etc. The advantages and drawbacks of these methods are analyzed, and promising lines of research in this field of applied biochemistry are described.

Amino Acid Sequence↗

PubMedDate not supplied

[Interaction between globular proteins and water-soluble carbodiimides].

Interactions of a number of globular proteins with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide were studied. Under conditions of carbodiimide excess at a protein concentration lower than 88.5 x 10(-5) mol/l, the crosslinking reaction was found to proceed exclusively by an intramolecular mechanism. This resulted in conformational changes in the protein secondary structure and decreased its biological activity. At higher protein concentrations, the reaction of intramolecular crosslinking was always the first to proceed, and only then intramolecularly crosslinked proteins interacted. The reaction of intermolecular crosslinking was not followed by a further change in the protein conformation and activity.

Carbodiimides↗