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Biomedical subjects

S M Andreev

Publications and source records attributed to S M Andreev.

26 records · Page 2Linked to original sources
PubMedDate not supplied

Immunological properties of allergen chemically modified with synthetic copolymer of N-vinylpyrrolidone and maleic anhydride.

Several conjugates of model allergen ovalbumin (OA) and the copolymer of N-vinyl pyrrolidone and maleic anhydride (VMA) modified with epsilon-aminocaproic acid (Acp) were prepared in different OA/Acp-VMA ratios. All conjugates were separated by ultrafiltration and analyzed by HPLC. Their compositions were determined by amino acid analysis and UV spectrometry. To detect immunogenicity, all conjugates were injected intraperitoneally into (CBAxC57BL/6)F1 mice three times in 3-week intervals in OA doses equivalent to 0.5, 10, and 100 micrograms/mouse. Only the conjugate containing 20%OA (OA(20%)-Acp-VMA) did not induce significant quantities of anti-OA IgE, but did induce anti-OA IgG antibodies in dose-dependent manner comparable to that of unmodified OA. Mixtures of OA and Acp-VMA or OA modified only with VMA without Acp activation with Acp induced dose-dependent anti-OA IgE and IgG antibody formation comparable to that of OA. Using passive cutaneous anaphylaxis, RAST inhibition and leukocyte histamine release, a significant reduction of allergenicity was noted using OA(20%)-Acp-VMA. This conjugate stimulated activation of the OA-specific T-cell hybrid 3DO-548 comparable to that of unconjugated OA. During experimental allergen-specific hyposensitization with OA(20%)-Acp-VMA, suppression of anti-OA IgE response and elevation of anti-OA IgG responses were noted when compared with unmodified OA. Selective blockade of B-cell epitopes of allergen may occur using the carrier Acp-VMA to reduce allergenicity while not affecting T-cell epitopes, thereby preserving immunogenicity. This approach of chemical modification of allergen suggests new opportunities in the creation of preparations for allergen-specific immunotherapy.

Allergens↗
PubMedDate not supplied

[Chemical modification of allergen leading to changes in its epitopic activity].

Modification of a model allergen ovalbumin (OA) with succinylation led to a decrease of its allergenicity measured by passive cutaneous anaphylaxis reaction, RAST inhibition assay and basophil histamine release. Modified OA stimulated OA-specific T-cell hybrid 3DO-548 to produce IL-2 at the same level as in case of non-modified OA. Modified OA did not induce anti-OA IgE, but did induce anti-OA IgG antibodies. This approach to chemical modification of allergen-selective blockade of B-cell epitopes while not affecting T-cell epitopes suggests new opportunities in creation of safe and effective allergovaccines.

Allergens↗
PubMedDate not supplied

[A study of hydrolysis of various synthetic peptides with gastrointestinal enzymes using thin-layer chromatography].

Hydrolysis in vitro of alpha- and epsilon-peptide bonds of synthetic amino acids and peptide substrates,--models of protein fragments, with digestive enzymes was studied. The kinetics of hydrolysis was studied by quantitative thin-layer chromatography followed by densitometric analysis of the chromatographic patterns. The rate constants of hydrolysis of Phe-Lys, Gly-Lys dipeptides and their epsilon-acetyl and epsilon-succinyl derivatives with leucine aminopeptidase and pancreatic enzymes were calculated. epsilon-Acyl residues of the substrates failed to split off under these conditions. The digestive enzymes hydrolysed the alpha-peptide bonds adjacent to the acylated lysine. Hydrolysis of epsilon-acetyl substrates proceeded faster as compared to epsilon-succinyl derivatives.

Amino Acids↗
PubMedDate not supplied

[Cross reactivity and amino acid structural homology of immunodominant peptide fragments of structural viruses from the human retroviruses HTLV-I, HTLV-II, HIV-1, and HIV-2].

Twelve synthetic peptides corresponding to 9 immunodominant regions of structural proteins of human retroviruses HTLV-I, HIV-1, and HIV-2 were studied in enzyme-linked immunosorbent assay for cross reactivity with heterotypical for each peptide anti-retroviral antibodies. The search of amino acid homologies was carried using the special computer program followed by the correspondence analysis of the discovered homologies and immunodominant fragments. It was found that peptides 100-130 p19 gag HTLV-I, 376-392 gp21 env HTLV-I, 381-400 gp21 env HTLV-I, 306-328 gp120 env HIV-1, 495-516 gp120 env HIV-1, 584-612 gp41 env HIV-1, and 581-603 gp36 env HIV-2 have type-specific reactivity and also cross react with 3-54% human sera containing antibodies against heterotypical retroviruses. On the other hand, peptides 120-130 p19 gag HTLV-I, 176-201 gp46 env HTLV-I, 291-312 gp46 env HTLV-I, 330-363 p24 gag HIV-1, and 602-624 gp41 env HIV-1 have shown no cross reactive properties; they may be effectively used for type-specific and differential serodiagnosis of human retroviral infections.

Amino Acid Sequence↗
PubMedDate not supplied

[Immunoreactivity of synthetic peptides, corresponding to B-cellular epitopes of human type I T-lymphotrophic virus structural proteins].

The immunoreactivity of 25 synthetic peptides corresponding to amino acid fragments of the HTLV-I structural proteins p19 gag, gp46 and gp21 env were studied in enzyme linked immunosorbent assay using a serum panel of 70 reference positive specimens with anti-HTLV-I antibodies. The location of the synthetic peptides containing the B-cell epitopes of HTLV-I was established. Anti-HTLV-I antibodies effectively recognized these peptides. The significance of some amino acids for forming the HTLV-I antigenic determinants was estimated. The synthetic peptides with amino acid sequences 100-130 p19 gag and 176-201 gp46 env were found to have most immunoreactivity (90-99% recognition by sera of HTLV-I infected patients) and mimic the immunodominant B-cell epitopes of HTLV-I structural proteins.

Amino Acid Sequence↗