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Biomedical subjects

S Elsayed

Publications and source records attributed to S Elsayed.

At least 91 records · Page 5Linked to original sources
PubMed1981

Allergenic synthetic peptide corresponding to the second calcium-binding loop of cod allergen M.

A peptide with the sequence of the second calcium-binding loop (EF loop) of cod Allergen M was synthesized by automatic solid-phase technique. The synthetic peptide corresponded to residues 88-103 of the known primary structure of Allergen M. The immunochemical reactivity of this loop, previously demonstrated for the overlapping enzymic fragments, was confirmed by using the synthetic preparation. The purified hexadecapeptide was shown to bind specifically to reaginic IgE from sera of cod-allergic individuals, in both in vivo and in vitro tests systems. It could also bind rabbit anti-Allergen M, as shown by rocket line immunoelectrophoresis and quantitative precipitation inhibition techniques. The findings emphasized that the immunological reactivity of the synthetic peptide (88-103) was compatible with a monovalent haptenic function: blocking and not eliciting allergic reactions.

Allergens↗
PubMed1981

Comparative studies on tree-pollen allergens. I. Isolation and partial characterization of a major allergen from birch pollen (Betula verrucosa).

A major allergen from birch pollen (Betula verrucosa) was isolated by a combination of gel permeation chromatography and preparative isoelectric focusing, and was found adequate for further immunological and chemical characterization. The crude aqueous pollen extract was eluted in 6 UV-absorbance peaks from an Ultrogel AcA-54 column. The main allergenic components were detected in two peaks of molecular weights 29,000 (BV4) and 40,000 daltons, respectively. BV4 contained one quantitatively dominating antigen as assessed by crossed immunoelectrophoresis, and was selected for further purification by isoelectric focusing. Column isoelectric focusing of BV4 gave four protein fractions with pI values corresponding to 5.18, 5.42, 5.76, and 5.94. The pI 5.18 protein was quantitatively dominating. This protein inhibited the radio-allergosorbent test in 8 out of 10 sera from birch pollen-sensitive individuals. Using a serum pool, the inhibition curve of BV4 pI 5.18 was parallel to that of the crude extract and gave a similar maximum inhibition. This allergen was shown to be homogeneous as judged by a single, symmetrical precipitate in crossed immunoelectrophoresis, one band in high-volt electrophoresis and a sharp strip in thin-layer analytical electrofocusing. Amino acid analysis showed a high content of serine. The N-terminal analysis as well as the carbohydrate concentration were preliminarily reported and will be confirmed in future studies.

Allergens↗
PubMed1980

A synthetic hexadecapeptide derived from allergen M imposing allergenic and antigenic reactivity.

A solid phase synthesis (SPPS) hexadecapeptide corresponding to residues 49-64 of allergen M from cod was found to bind specifically IgE antibodies from sera of cod-allergic individuals. The SPPS peptide was similarly reactive in IgG-mediated reactions; it could interfere with Allergen M line precipitate in rocket-line immunoelectrophoresis, giving a distinct deflection. It is the only reported synthetic polypeptide imposing allergenic and antigenic reactivity. The hexadecapeptide is composed of two homologous tetrapeptides located at its terminai, tentatively concluded to be mutually critical for the immunological specificity. The data obtained confirmed the predicted reactivity of the Ca2+-binding CD loop of the intact Allergen M.

Allergens↗
PubMed1980

Proteinuria after selective nephroangiography in man. Comparison of three contrast media.

The proteinuria following aortography and selective nephroangiography in 60 patients using Isopaque Cerebral, Urografin 60% and Amipaque was investigated. The results indicate an increase in glomerular permeability and possibly an overload of tubular reabsorptive capacity after angiography. The changes are transient. No permanent injury to the kidney appears to occur.

Albuminuria↗
PubMed1979

The allergenic structure of allergen M from cod. III. Studies on the antigenicity of long-sequence peptides.

Fragments TM 1 (75 amino acid residues) and TM 2 (38 amino acid residues), and 3 other polypeptides (range 16-25 amino acid residues) of Allergen M from cod were shown to be active in rabbit IgG-mediated reactions. The same peptides were previously found to possess reactivity in IgE-mediated reactions, thus suggesting a structural relationship between their antigenic and allergenic determinants.

Absorption↗
PubMed1979

The indirect rat mast cell degranulation test reconsidered.

The indirect rat mast cell degranulation test for the detection of human reaginic antibodies was reinvestigated. When the mast cells were incubated with human reaginic serum at concentrations exceeding approximately 3%, a massive, non-specific histamine release occurred, irrespective of the presence or absence of allergen. At tolerated serum concentrations (below 3%), the allergen concentration did not influence the release process. We conclude that the indirect rat mast cell test is not applicable as an alternative test system for the study of immediate hypersensitivity in humans.

Allergens↗
PubMed1978

Crossed immunoelectrophoretic and crossed radioimmunoelectrophoretic studies employing a model allergen from codfish.

A standard reference pattern in crossed immunoelectrophoresis (CIE) of the parvalbumin fraction of a cod white muscle extract was established. Crossed line immunoelectrophoresis (CLIE), tandem CIE and crossed radioimmunoelectrophoresis (CRIE) were used to identify the major allergens, thereby establishing a basis for future work employing quantitative immunoelectrophoretic techniques in the study of codfish allergens. Rocket immunoelectrophoresis and rocket-line immunoelectrophoresis were used to demonstrate antigenic determinants on polypeptide fragments of the major allergen, Allergen M. The results show the usefulness of these techniques in studies of antigenic determinants on non-precipitating polypeptides. CRIE with 8 patients's sera showed radiostaining indicating IgE binding corresponding to at least 7 precipitates in the crude extract CIE preparations. The purified DS 22 fraction was shown to contain 2 CRIE-positive (IgE-binding) precipitates. When using Allergen M, these precipitates were also demonstrated, one of them in trace amounts only.

Allergens↗
PubMed1977

Allergenic structure of allergen M from cod. II. Allergenicity of the limited tryptic hydrolysis peptides of fragment TM 2.

The peptides P1B3 (amino acid residues No. 88-113) and LT3N1 (residues No. 88-108), obtained from the limited tryptic hydrolysis of fragment TM 2 from codfish allergen M inhibited the interaction between allergen M and reaginic IgE antibodies both in vitro (87 and 62% RAST inhibition, respectively) and in vivo (total PK test inhibition). The peptide A7B1 (residues No. 97-113) overlapping the former at the COOH-terminus, was inactive in PK test inhibition experiments and produced only a minor inhibition of RAST (15%). The findings suggest that the nonapeptide residue No. 88-96 is partially indispensible for the allergenic activity of fragment TM 2, and is likely to incorporate allergenic determinant(s).

Allergens↗
PubMed1976

The allergenic structure of allergen M from cod. I. Tryptic peptides of fragment TM 1.

In attempts to locate the allergenic active sites of fragment TM 1 of allergen M from cod, the allergenicity of the tryptic hydrolysis peptides was examined both in vivo and in vitro. A duodecapeptide (residues No. 33-44) was tentatively suggested to incorporate at least one allergenic determinant. All the tryptic peptides were less active than allergen M as shown by the in vivo titration experiments. The activity of the peptides was not due to contamination of intact allergens.

Allergens↗
PubMed1975

The primary structure of allergen M from cod.

The complete primary structure of allergen M of cod (Gadus callarias L.) is presented. The amino acid sequence of fragment TM1, the NH2-terminal peptide of allergen M, was elucidated by the dansyl-Edman method. It consists of 75 amino acids and 1 glucose residue (mol. wt. 8,492). By summation of the sequence data of fragment TM1 and the previously reported fragment TM2, the intact allergen M has 113 residues (mol. wt. 12,328). Fragment TM1 of cod shows less homology (30.6 percent) with the corresponding fragments of other reported fish species than does fragment TM2 (42.1 percent); the intact allergen M shows 34.5 percent homology. The single half cystine of allergen M was shown to be blocked. Gas chromatographic analysis of the reduced and nonreduced allergen M suggested that the glucose is bound to Cys 18 through an S-glucosidic bond.

Allergens↗
PubMed1975

Physico-chemical properties and specific activity of a purified allergen (codfish).

The major allergen (Allergen M) from codfish is an acidic protein, mol. wt. 15000 with 114 amino acid residues and only one sugar (glucose) residue. It is highly active in skin testing on codfish-allergic individuals, in passive transfer (PK) testing and in the radioallergosorbent test (RAST). The activity resists denaturation and incomplete tryptic hydrolysis. Two fragments (TM 1, mol. wt. 8500, and TM 2, mol. wt. 6500) are obtained from allergen M. The fragments are equally active and allergenically identical in biological tests, but somewhat less active than Allergen M itself. Smaller peptides obtained from TM 2 are inactive. The amino acid sequence of TM 2 is given as the first reported example of a full structural analysis of an active allergen. The information obtained in studies of this model allergen is compared with information published from other studies of allergens. Similarities and differences are pointed out.

Allergens↗