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S T Cox

Publications and source records attributed to S T Cox.

34 records · Page 2Linked to original sources
PubMed2000

HLA-B*4413 identified in a UK Caucasoid potential bone marrow donor.

We describe a novel allele belonging to the B*44 allele group. HLA-B*4413 was identified in a Caucasoid potential bone marrow donor from the Anthony Nolan Bone Marrow Trust register. Initial HLA typing of this donor revealed unusual serological reactivity. Further investigation was carried out by reference strand conformation analysis (RSCA) and sequence-based typing (SBT) using DNA extracted from an Epstein-Barr virus (EBV)-transformed B-cell line made from this donor (AMI005AN). In this individual, two B*44 alleles were revealed upon initial investigation: B*4409 and a previously unseen allele which has been named B*4413. B*4413 is identical to B*44031 except for a unique nucleotide substitution resulting in an amino acid difference at residue 61 in the alpha1 helix.

Base Sequence↗
PubMed2000

HLA-A*6817, identified in the Kolla Amerindians of North-West Argentina possesses a novel nucleotide substitution.

Analysis of HLA polymorphism of the indigenous populations of Central and South America has identified many alleles not seen previously in other populations. We have described a novel allele, B*5113, previously in a Kolla Amerindian individual from North-West Argentina. Here we present a second novel allele from this population: A*6817, which differs from its closest neighbour A*68012 by a single substitution at nucleotide 419. This substitution of adenosine 419 A*68012 for thymidine in A*6817 results in a novel amino acid change (aspartate to valine) at residue 116.

Argentina↗
PubMed2000

A new allele, HLA-B*1555, identified in an African patient awaiting bone marrow transplantation.

Human HLA genes exhibit extreme polymorphism, the extent of which is emphasised by the identification of an ever increasing number of new alleles by DNA-based typing strategies. Here we describe a novel allele, belonging to the HLA-B*15 group, which was identified in an African patient awaiting a bone marrow transplant This individual was shown to exhibit two HLA-B alleles, B*5301 and a new allele which has been named B*1555. B*1555 differs from B*1531 in exon 3 by a single nucleotide substitution. This substitution results in a change in the amino acid residue at position 97, which is located within the beta-pleated sheet region of the HLA molecule.

Africa↗
PubMed2000

HLA-B*8202 identified in a Caucasoid potential bone marrow donor.

Sequence analysis of HLA class I alleles has continued to reveal the true extent of polymorphism, particularly for B-locus alleles. This diversity can arise through reshuffling of polymorphic sequences generated by point mutation, resulting in interallelic recombination or intergenic recombination (1). Here we describe a new B-locus allele, B*8202, which is structurally most similar to B*8201, having only one nucleotide difference in exon 3 at nucleotide 557, resulting in an amino acid change of aspartic acid to glycine at residue 162. Glycine is the consensus amino acid for B-locus alleles, which suggests that B*8202 is older than B*8201 in evolutionary terms. B*8201 was found to be a hybrid of B*4501 and B*5602 that may have arisen through recombination events, explaining the serological patterns observed with these allotypes. The importance of high-resolution typing is emphasised here as routine typing suggested the presence of B*8201 and the new variant allele may have been missed had it not been typed further by sequence-based typing.

Alleles↗
PubMed1999

HLA-A, -B, -C polymorphism in a UK Ashkenazi Jewish potential bone marrow donor population.

To further our knowledge of HLA polymorphism in different ethnic populations and to increase the number of full HLA class I typed potential bone marrow donors on the Anthony Nolan Bone Marrow Trust register, HLA-A, -B and -C polymorphism was characterised in 412 Ashkenazi Jewish potential donors. Serological typings and limited molecular analysis was performed for HLA-A and -B, and molecular typings were performed for HLA-C. Gene and haplotype frequencies were calculated using the maximum likelihood method and compared with UK Caucasoid and other Jewish populations. While the specificities identified were in general overlapping with the UK Caucasoid data, a difference in the frequencies of individual specificities was observed. For example, HLA-B62, a common serotype found in the UK Caucasoid population, is almost absent in the Ashkenazim. HLA-A, -C, -B haplotype frequencies also differ between the two populations with A26-Cw*1203-B38 and A24-Cw*04-B35 significant in the Ashkenazim, whilst A1-Cw*07-B8, a common Caucasoid haplotype, was found to be less frequent. Overall the results for the UK Ashkenazi population were most similar to previous reports on Polish/Russian Jews.

Adolescent↗
PubMed1999

Sequence of HLA-A*6808.

A novel HLA-A*68 allele was identified by reference strand conformation analysis of a DNA sample studied for the International Cell Exchange program. Direct sequencing of HLA-A locus PCR products confirmed the presence of A*6602 and an A*68 allele which differed from A*68011 by two nucleotides at positions 538 and 539. The presence of this sequence motif in this allele which has been named A*6808 was verified by DNA sequencing of full-length A*6808 clones. No other coding differences between A*68011 and A*6808 were identified. The two nucleotide substitutions found in A*6808 effect an amino acid difference in the encoded protein at residue 156 within the peptide binding site which may evoke alloreactive immune response after HLA-A68 mismatched transplants.

Black People↗
PubMed1999

Novel intronic variants of MICB (MHC class I chain-related gene B).

We report an eight-nucleotide duplication in intron 4 of the MICB allele 01021, which was found in samples from different ethnic backgrounds and in association with several HLA-B alleles. We suggest that this new MICB allele is evolutionarily older than HLA-B alleles.

Alleles↗
PubMed1998

Application of RSCA for the typing of HLA-DPB1.

We describe the application of RSCA, for the high resolution typing of alleles encoded at the HLA-DPB1 locus. RSCA differs from other sequence based typing methodologies in that the HLA type is assigned on the basis of differences in DNA conformation between different alleles. A total of 251 samples were typed in a blind study, of these 109 samples had been typed previously by conventional techniques. A comparison of the RSCA data with the historical typing results showed a concordance over 93%. Seven samples initially had discordant results, however, when these samples were typed by direct sequencing, the type assigned by RSCA was found to be correct in all but one case, indicating a concordance over 99%. RSCA has proved to be a simple reliable technique for the typing of the HLA-DPB1 locus, and is not limited by the ambiguous combinations of alleles determined in other conventional techniques.

Alleles↗
PubMed1979

Interaction of choriocarcinoma cells and human peripheral blood lymphocytes. Resistance of cultured choriocarcinoma cells to cell-mediated cytotoxicity by mitogen-activated lymphocytes.

Cultured choriocarcinoma (Be Wo) cells exist that share many of the morphologic and bio-synthetic properties of normal human trophoblasts. In an attempt to develop a model for the immunologic relationship between a sensitized mother and fetus, we mixed Be Wo cells with mitogen-activated cytotoxic lymphocytes in vitro. Be Wo cells were resistant to the cytolytic effects of the activated lymphocytes despite 24-h exposure and intimate cell-to-cell contact as determined by microscopy. Control target cells, a line of human hepatoma cells, were readily destroyed. Cytotoxicity was measured by determining residual radioactivity of [(3)H]thymidine-labeled target cells after exposure to activated lymphocytes. Employing the quantitative assay, we confirmed the morphologic results and showed that Be Wo and a number of other choriocarcinoma cell lines were resistant to the cytotoxic effects of lymphocytes activated by phytohemagglutinin, pokeweed mitogen, and allogeneic cells in mixed lymphocyte cultures. Moreover, Be Wo cells were resistant to injury over a wide range of killer to target cell ratios. Significant killing of the Be Wo cells occurred only after prolonged exposure (48 and 72 h) to the activated lymphocytes. We suggest that one mechanism that may assist the fetus (or a choriocarcinoma) in its immunologic survival is the intrinsic resistance of trophoblast cells to lymphocyte-mediated cytotoxicity.

Cells, Cultured↗
PubMed1978

The bactericidal potential of various endodontic materials for primary teeth.

An in vitro study of the bactericidal or bacteriostatic effects of several pulp therapy compounds and their components on selected bacterial commonly isolated from infected primary teeth was undertaken. It was determined that zinc oxide had no inhibitory effects on E. coli, Staph. aureus, and Strep. viridans; however, the addition of eugenol to this system retarded the growth of only the grampositive organisms. The inclusion of zinc acetate as a setting accelerator inhibited both gram-positive and gram-negative bacteria. Also the inhibitory effects on these three organisms could be greatly enhanced by the addition of formocresol or paraformaldehyde to the zinc oxide--eugenol--zinc acetate system. It was also noted that Sargenti's N-2 paste was apparently no more effective in retarding growth of these organisms than the mixtures. Only the lead tetroxide and hydorcortisone present in the N-2 paste was toxic to the Staph. aureus but not to E. coli or to Strep. viridans. The other heavy metals in N-2 apparently have no antibacterial activity in the manner in which they were tested. This evidence suggests, but is not conclusive, that zinc oxide--eugenol--zinc acetate, with or without formaldehyde-containing compounds, may be effective in the elimination of bacteria from pulpotomized primary teeth. Therefore, the addition of highly cytotoxic chemicals which will remain sealed in a root canal and be active for extended periods of time may not be necessary for successful treatment.

Anti-Bacterial Agents↗
PubMed1968

Arylamidase of Neisseria catarrhalis.

Neisseria catarrhalis produces arylamidase intracellularly and is one of the gram-negative bacteria producing exceptionally large amounts of this enzyme. In general, gram-positive bacteria do not produce this enzyme. Arylamidase from N. catarrhalis was purified by salt fractionation, chromatography, and density gradient ultracentrifugation. Its sedimentation coefficient was 6.6; l-alanine-beta-naphthylamide (betaNA) was the most rapidly hydrolyzed amino acid-betaNA. The enzyme had pK(e) values of 6.1 and 8.7 and pK(es) values of 7.1 and 7.9; only those amino acid-betaNA compounds of the l configuration were susceptible to hydrolysis. Arylamidase catalyzed stepwise hydrolysis of dipeptide-betaNA, beginning with the N-terminal residue. Substrates having amino acid residues with larger R groups, such as leucine, interacted much more effectively with enzyme. The significance of the predominate occurrence of arylamidase activity in gram-negative bacteria and the role of this enzyme in the physiology of these organisms remain unclear. It has been established, however, that arylamidase is distinct from leucine aminopeptidase.

Amidohydrolases↗