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Biomedical subjects

A R Duncan

Publications and source records attributed to A R Duncan.

7 recordsLinked to original sources
PubMed2003

Cytology suggestive of glandular neoplasia: outcomes and suggested management.

Eighty-three cases having a cervical smear result showing abnormal glandular cells were identified and matched up with the diagnostic histology result. Thirty-four (41.0%) were associated with malignancy and 26 (31.3%) with a cervical intraepithelial lesion without invasion. Thirty-eight (45.8%) had conditions of the cervix as follows: 12 cases had invasive disease of the cervix; nine (10.8%) adenocarcinoma of cervix and three (3.6%) squamous carcinoma of cervix. Nineteen (22.9%) had cervical intraepithelial neoplasia (CIN/SIL) alone and seven (8.4%) had cervical glandular intraepithelial neoplasia (CGIN) +/- CIN. There were 16 (19.3%) cases with malignancies of the uterine corpus and six (7.2%) had a malignancy arising from another primary site. Twenty-three (27.7%) had no malignant or pre-malignant condition. The risk of malignancy was related to age and ranged from 18.2% in those under 35 years to 67.9% in those 55 years and over. A protocol for the management of these cases is described.

Adenocarcinoma↗
PubMed1998

Strategies for selection of antibodies by phage display.

Phage antibody-display is rapidly maturing into a very effective tool for antibody generation. The recent development of large primary antibody libraries enables selection of antibodies against most targets in under two weeks and many of these antibodies have relatively high (nanomolar) affinities. Successful strategies have also been developed to affinity mature these antibodies into the picomolar range if required.

Animals↗
PubMed1996

Phage diabody repertoires for selection of large numbers of bispecific antibody fragments.

Methods for the generation of large numbers of different bispecific antibodies are presented. Cloning strategies are detailed to create repertoires of bispecific diabody molecules with variability on one or both of the antigen binding sites. This diabody format, when combined with the power of phage display technology, allows the generation and analysis of thousands of different bispecific molecules. Selection for binding presumably also selects for more stable diabodies. Phage diabody libraries enable screening or selection of the best combination bispecific molecule with regards to affinity of binding, epitope recognition and pairing before manufacture of the best candidate.

Animals↗
PubMed1992

Multiple binding sites on the CH2 domain of IgG for mouse Fc gamma R11.

Important mammalian defensive functions such as phagocytosis are triggered in leukocytes by the interaction of the Fc region of IgG with cell surface receptors (Fc gamma R). The CH2 domain of IgG has been implicated previously as the site of interaction with human and mouse Fc gamma R. This domain was mapped for interaction with mouse Fc gamma R11 expressed by the macrophage-like cell line P388D1, using two panels of a total of 32 site-directed mutants of mouse IgG2b and chimeric human IgG3 monoclonal antibodies. Two potential binding sites have been identified: one in or within the vicinity of the lower hinge site on IgG for human Fc gamma R1, and one within the binding site on IgG for Clq. The three mutant IgGs (Gly 237----Ala, Asn 297----Ala, and Glu 318----Ala) which do not interact in complexed form also fail to bind as monomers. A 1H NMR study of the three non-binding monomeric mutants suggests that the mutations are largely site-specific, indicating that IgG interacts with mouse Fc gamma R11 at two regions within the CH2 domain. This interaction dictates phagocytosis mediated by Fc gamma R11 of the P388D1 cell line.

Animals↗
PubMed1988

The binding site for C1q on IgG.

In humoral defence, pathogens are cleared by antibodies acting as adaptor molecules: they bind to antigen and trigger clearance mechanisms such as phagocytosis, antibody-dependent cell-mediated cytotoxicity and complement lysis. The first step in the complement cascade is the binding of C1q to the antibody. There are six heads on C1q, connected by collagen-like stems to a central stalk, and the isolated heads bind to the Fc portion of antibody rather weakly, with an affinity of 100 microM (ref. 3). Binding of antibody to multiple epitopes on an antigenic surface, aggregates the antibody and this facilitates the binding of several C1q heads, leading to an enhanced affinity of about 10 nM (ref. 1). Within the Fc portion of the antibody, C1q binds to the CH2 domain. The interaction is sensitive to ionic strength, and appears to be highly conserved throughout evolution as C1q reacts with IgG from different species (for example see ref. 8). By systematically altering surface residues in the mouse IgG2b isotype, we have localized the binding site for C1q to three side chains, Glu 318, Lys 320 and Lys 322. These residues are relatively conserved in other antibody isotypes, and a peptide mimic of this sequence is able to inhibit complement lysis. We propose that this sequence motif forms a common core in the interactions of IgG and C1q.

Animals↗
PubMed1988

Localization of the binding site for the human high-affinity Fc receptor on IgG.

A major pathway in the clearance of pathogens involves the coating of the pathogen with specific antibodies, and the binding of the antibody Fc region to cell receptors. This can trigger engulfment of the pathogen by phagocytes or lysis by killer cells. By oligonucleotide site-directed mutagenesis we have engineered a single amino acid change in a mouse IgG2b antibody (Glu 235----Leu) which now enables the antibody to bind to the FcRI (high affinity) receptor on human monocytes with a 100-fold improvement in affinity. This indicates that Leu 235 is a major determinant in the binding of antibody to FcRI and that the receptor may interact directly with the region linking the CH2 domain to the hinge. Tailoring the affinity of antibodies for cell receptors could help dissect their role in clearing pathogen.

Amino Acid Sequence↗