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Biomedical subjects

D G Harle

Publications and source records attributed to D G Harle.

At least 19 recordsLinked to original sources
PubMed1990

The specificity of the binding of platelet activating factor (PAF) to anti-PAF antibodies.

Quantitative hapten inhibition experiments employing sheep anti-PAF antibodies and selected PAF analogues were undertaken with the aim of defining the antigenic determinant structures complementary to the antibody combining sites. The most important fine structural features for inhibition of antibody to PAF were shown to be an acetyl group at position 2 of the phospholipid glycerol backbone and an ether group at position 1. Of the naturally occurring compounds, C16- and C18:1-PAF proved to be the most potent inhibitors and more active than C18-PAF while phospholipids with a propionyl, butyryl or hexanoyl group at position 2 showed either weak or no inhibitory activity. The 1-acyl, thioether and deoxy analogues proved inactive. Variations in the polar head group of PAF were found to be less critical with, for example, the dimethyl and ethanolamine derivatives retaining some activity. This antibody recognition pattern is very similar to that of the PAF receptor, although the antibodies appear to have a more specific requirement for an acyl linkage at position 2.

Animals↗
PubMed1990

Identification of penicillin allergenic determinants that bind IgE antibodies in the sera of subjects with penicillin allergy.

Much of the literature on penicillin hypersensitivity is devoted to the identification of penicillin antigens rather than allergens. Human IgE-binding determinants on different penicillins have rarely been closely investigated with the view of defining fine structural allergenic features and differences. We have developed radioimmunoassays employing ampicillin, amoxicillin and ticarcillin solid phases for the detection of penicillin-reactive IgE antibodies. Quantitative hapten inhibition studies employed to identify IgE-binding regions on the penicillin molecules revealed a heterogeneous group of allergenic determinants consisting exclusively, or in part, of the alpha-aminobenzyl and benzyl side chain groups and the beta-lactam and thiazolidine rings of the penicillin nucleus.

Adult↗
PubMed1990

Immunoassays employing substituted ammonium compounds other than neuromuscular blocking drugs to increase the detection of IgE antibodies to these drugs.

Subjects who experience life-threatening anaphylactic reactions to neuromuscular blocking drugs frequently have serum IgE antibodies that react with substituted ammonium groups on the drugs. Failure to detect drug-reactive antibodies may be due to the nature of the drug-solid support used for testing sera. With this in mind, solid phases of some selected compounds containing substituted ammonium groups, in particular triethylamine and morphine, were prepared and used to screen sera in an attempt to increase the frequency of detection of IgE antibodies complementary to tertiary and/or quaternary ammonium groups. For subjects who experienced an anaphylactic reaction to succinylcholine or gallamine, use of the supplementary assays increased the frequency of detection from 83 to 100%. For d-tubocurarine and alcuronium, detections increased from 92 to 100% and from 67 to 88%, respectively. Molecular models revealed a clear structural similarity between the conformations of the trialkylammonium groups on one face of the molecules of morphine and d-tubocurarine.

Anaphylaxis↗
PubMed1990

The molecular basis of IgE antibody binding to thiopentone. Binding of IgE from thiopentone-allergic and non-allergic subjects.

Thiopentone-specific IgE antibodies from the sera of subjects who experienced a life-threatening anaphylactic reaction to the drug and IgE antibodies that cross-react with thiopentone via substituted ammonium groups in either cyclic or acyclic form, were studied by direct binding immunoassays and quantitative hapten inhibition methods. Findings provided an explanation for the apparent 'non-specific' nature of some IgE antibody reactions with thiopentone and reinforce the conclusion that the thiopentone IgE immunoassay is a valuable aid in the diagnosis of immediate allergic reactions to the drug.

Anaphylaxis↗
PubMed1990

Combining site specificities of rabbit antibodies to platelet-activating factor (PAF).

Anti-PAF sera from six different rabbits, immunized with C12- or C6-PAF as immunogen, were examined in hapten inhibition experiments in an attempt to define the fine structural recognition specificities of the antibody combining sites. Using a selection of naturally occurring lipids and PAF analogues, no significant cross-reactivity was observed with the lipids or with the inactive metabolite, lyso-PAF. Comparison of the structural specificity requirements of the antibodies from each rabbit showed some heterogeneity, with one antiserum demonstrating a different recognition specificity at position 1 on the glycerol backbone of the PAF molecule. A second rabbit antiserum showed a large degree of tolerance for analogues with increasing acyl chain length at position 2. In general, an ether group at position 1 and an acetyl at position 2 were required for inhibitory activity and a degree of tolerance was demonstrated at position 3, where the main structural requirement was for one or more methyl groups on the nitrogen atom of the phosphocholine moiety.

Animals↗
PubMed1990

Drugs as allergens: an immunoassay for detecting IgE antibodies to cephalosporins.

A radioimmunoassay employing cephalothin linked to a solid phase has been developed for the detection of cephalosporin-reactive IgE antibodies. Direct binding and inhibition studies demonstrated allergenic cross-reactivity between cephalosporins and penicillins, and quantitative hapten inhibition experiments identified the 2-thiophene group, and particularly the attached methylene group, of cephalothin as an allergenic determinant.

Animals↗
PubMed1989

Anaphylaxis following administration of papaveretum. Case report: Implication of IgE antibodies that react with morphine and codeine, and identification of an allergenic determinant.

IgE antibodies that reacted with morphine and codeine were detected in the serum of a subject who experienced a life-threatening anaphylactic reaction following the administration of Omnopon-Scopolamine (papaveretum-hyoscine). Hapten inhibition studies with morphine and a number of structurally-related analogues revealed that morphine and codeine were the most potent inhibitors of IgE binding to a morphine-solid phase. Nalorphine, meperidine, and methadone were also good inhibitors of IgE binding, but naltrexone, buprenorphine, and fentanyl proved to be poor inhibitors. From a detailed examination of structure-activity relationships, the authors conclude that the important structural features of the morphine allergenic (that is, IgE binding) determinant comprises the cyclohexenyl ring with a hydroxyl group at C-6 and, most important of all, a methyl substituent attached to the N atom. The authors' findings suggest that morphine analogues administered to such a patient may provoke clinical anaphylaxis. Hyoscine reacted weakly with IgE antibodies in the subject's serum, but this was thought to be due to weak cross-reaction between this compound and morphine.

Anaphylaxis↗
PubMed1988

Structural features of potent inhibitors of rat kidney histamine N-methyltransferase.

Three antimalarial drugs amodiaquine, quinacrine and chloroquine were compared side-by-side with the antiseptic agent chlorhexidine and the neuromuscular blocker alcuronium for their capacity to competitively inhibit in vitro the activity of the enzyme histamine N-methyltransferase (HMT) from rat kidney over the concentration range 10(-3)-10(-8). Amodiaquine was clearly the most potent HMT inhibitor followed by quinacrine, chlorhexidine, alcuronium and chloroquine. Investigation of the structure-activity relationships by examining space-filling models revealed marked similarities in the conformations of the arrangement of three N atoms in histamine and in each of the compounds tested.

Alcuronium↗
PubMed1988

Drugs as allergens: detection and combining site specificities of IgE antibodies to sulfamethoxazole.

An immunoassay was developed for the detection of sulfamethoxazole reactive IgE antibodies in the sera of patients who experienced life threatening anaphylactic reactions following the ingestion of co-trimoxazole (trimethoprim and sulfamethoxazole). Patients who had significant levels of sulfamethoxazole reactive IgE antibodies in their sera did not have IgE antibodies that reacted with trimethoprim-Sepharose. Inhibition experiments with a number of sulfonamides to determine the fine structural specificities of the sulfamethoxazole reactive IgE antibodies in three patients revealed that sulfamethoxazole and, depending on the serum, sulfamerazine and sulfamethizole, were the most potent inhibitors of IgE binding, whereas the parent sulfonamide, sulfanilamide, was a very poor inhibitor. From a detailed examination of structure-activity relationships, we concluded that the 5-methyl-3-isoxazolyl group on the sulfamethoxazole molecule was the allergenic determinant for all three patients with the 5-methyl group being particularly important for IgE antibody recognition. The assays for the detection of IgE antibodies to sulfamethoxazole and trimethoprim should prove useful for the diagnosis of immediate hypersensitivity to co-trimoxazole and perhaps for monitoring drug therapy in AIDS patients where a high incidence of adverse reactions to co-trimoxazole has been reported.

Adult↗
PubMed1988

Drugs as allergens. The molecular basis of IgE binding to trimethoprim.

The combining site specificities of IgE antibodies that react with the oral antibacterial agent trimethoprim and found in the sera of two subjects who experienced anaphylaxis after taking the drug, were investigated. Hapten inhibition studies with some close analogues of trimethoprim and a range of other structurally related compounds showed that the allergenic determinant complementary to the IgE antibodies in the serum of one of the subjects was the 3,4-dimethoxybenzyl group. The complementary allergenic structure recognized by the IgE antibodies in the serum from the second subject comprised both the trimethoxybenzyl and diaminopyrimidine rings of trimethoprim. Thus, as with thiopentone, but unlike the neuromuscular blocking drugs, the trimethoprim molecule has more than one determinant each with the capacity to provoke IgE formation, interact with the antibody combining site and provoke drug-induced allergic reactions. The general approach set out here employing carefully selected structural analogues in hapten inhibition studies should be invaluable for confirming specificity and identifying allergenic determinants in IgE antibody-mediated allergic drug reactions.

Allergens↗
PubMed1987

An immunoassay for the detection of IgE antibodies to trimethoprim in the sera of allergic patients.

An immunoassay was developed to detect IgE antibodies to the widely used antibacterial drug trimethoprim. Significant levels of trimethoprim-reactive IgE antibodies were found in the sera of two patients who had experienced life-threatening allergic reactions following administration of a combination of trimethoprim and sulphamethoxazole. No IgE antibodies reactive with sulphamethoxazole were found in the sera of either patient. Inhibition experiments revealed that a high degree of cross-reactivity occurs between the drug-reactive IgE antibodies and two structural analogues of trimethoprim, 6-hydroxy- and 6-chlorotrimethoprim. These experiments also indicated that the combining sites of the trimethoprim-reactive IgE antibodies in the two sera were probably complementary to different parts of the trimethoprim molecule. The assay should supplement skin testing in determining the offending drug in patients with suspected allergic sensitivity to trimethoprim-sulphamethoxazole complex.

Adult↗
PubMed1987

Drugs as allergens: the molecular basis of IgE binding to thiopentone.

Using an immunoassay developed for the detection of thiopentone-reactive IgE antibodies, the combining site specificities of such antibodies found in sera of patients who experienced life-threatening anaphylactic reactions to the drug were studied. The antibody combining sites from one patient were complementary to the region of the thiopentone molecule containing a thio group at position 2 of the barbiturate ring. The allergenic determinant recognized by IgE antibodies from another patient encompassed a secondary pentyl group and an ethyl group attached to position 5 on the other side of the barbiturate ring. Thus, it is already clear that there is more than one allergenic determinant on the thiopentone molecule with the capacity to provoke IgE formation and drug-induced allergic reactions.

Allergens↗
PubMed1986

Antigenic similarity between the protein neurotoxin alpha-bungarotoxin and neuromuscular blocking drugs.

The snake neurotoxins alpha-bungarotoxin (alpha-BGT) and beta-bungarotoxin (beta-BGT) which act at the neuromuscular junction, were found to bind to IgE antibodies directed against neuromuscular blocking (NMB) drugs in the sera of two patients who had experienced lifethreatening anaphylactic reactions to succinylcholine. alpha-BGT inhibited IgE-binding to a choline-Sepharose solid support in one patient better than the NMB drug alcuronium, choline, triethylcholine and beta-BGT. IC50s for alpha-BGT and succinylcholine were 16 and 10 nmol respectively for one patient and 34 and 6.0 nmol for the other. Recognition of the NMB drugs and alpha-BGT by the same antibody is the first demonstration of an antigenic similarity between these drugs and the protein toxin.

Anaphylaxis↗
PubMed1986

Detection of thiopentone-reactive IgE antibodies following anaphylactoid reactions during anaesthesia.

A radioimmunoassay was developed to detect IgE antibodies to the anaesthetic induction agent thiopentone. Significant levels of thiopentone-reactive IgE antibodies were found in the sera of two patients who had experienced life-threatening anaphylactoid reactions following administration of the drug. Inhibition experiments revealed that cross-reactivity occurs between the drug-reactive IgE antibodies and four barbiturate analogues pentobarbitone, phenobarbitone, barbitone and methohexital. The assay should supplement skin testing for the detection of patients with potentially lethal sensitivity to thiopentone.

Anaphylaxis↗
PubMed1985

Assays for, and cross-reactivities of, IgE antibodies to the muscle relaxants gallamine, decamethonium and succinylcholine (suxamethonium).

Two radioimmunoassays have been developed to detect IgE antibodies to succinylcholine, decamethonium and gallamine in the sera of patients who have experienced life-threatening anaphylactoid reactions following administration of a muscle relaxant drug. They involve the coupling of choline and its ethyl analogue, triethylcholine to activated Sepharose. A high degree of cross-reactivity was shown to occur between drug-reactive IgE antibodies and 6 muscle relaxants as well as choline and triethylcholine. Results suggest that the specificities of the IgE antibodies are directed towards quaternary or tertiary ammonium ions on the drugs that bind the antibodies. Molecular models of these compounds support the structure-activity relationships determined in the inhibition studies.

Antibody Specificity↗