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T Robson

Publications and source records attributed to T Robson.

44 records · Page 3Linked to original sources
PubMed1988

Antigenic determinants expressed by human C4 allotypes; a study of 325 families provides evidence for the structural antigenic model.

The antigenic determinants of human C4 have been defined by human IgG antisera, Rodgers (Rg) and Chido (Ch), in hemagglutination-inhibition assays (HAI). Eight (2 Rg and 6 Ch) are of high frequency, greater than 90%, and 1, WH, is of low frequency, 15%. The phenotypic combinations are complex; generally, C4A expresses Rg, and C4B has Ch, but reverse antigenicities have been established both by HAI and by sequence data of selected C4 allotypes. A study of 325 families provides data on the antigenic expression of each C4 allotype and demonstrates strong associations. A structural model for the antigenic determinants of C4 proteins has been proposed and is completely supported by the family material. Of the 16 possible antigenic combinations for C4 proteins, only 3 are undetected. A new Ch combination has been recorded in two French families. The reported sequence variation within the C4d region can account for the antigenic determinants but leaves the location of electrophoretic variation in C4 still unclear.

Blood Group Antigens↗
PubMed1973

The catalase activity of ferrihaems.

1. The variation of the specific stoicheiometric catalatic activity of proto- and deuteroferrihaem with total ferrihaem concentration has been studied at 25 degrees C over a wide range of pH. For deuteroferrihaem the results imply that only monomeric ferrihaem species contribute significantly to the catalatic activity. Protoferrihaem is more highly dimerized in solution and, in this system, contributions to the catalatic activity from both monomeric and dimeric ferrihaem species were observed. The ratio of the specific activity of protoferrihaem monomer to that of dimer varied from approximately 20 at pH7 to 5x10(4) at pH12.2. 2. The specific activity of protoferrihaem monomer closely resembles that of deuteroferrihaem monomer, both in magnitude and pH-dependence. In both cases the activity is inversely proportional to [H(+)]. In contrast, the activity of catalase is independent of pH in the range 5-10. At pH13 the activity of ferrihaem monomer becomes equal to the maximal activity of catalase. The results are in good agreement with those reported by Brown et al. (1970b) and provide support for the assumptions upon which this previous analysis relied. 3. Information from the literature concerning the catalatic activity and dimerization of the iron(III) complex of 4,4',4'',4'''-tetrasulphophthalocyanine (Waldmeier & Sigel, 1971; Sigel et al., 1971) have been re-analysed. The results imply that both the monomeric and dimeric complexes contribute to catalatic activity and these activities closely resemble those of the corresponding protoferrihaem species.

Catalase↗
PubMed1973

Oxidation of deuteroferrihaem by hydrogen peroxide.

1. The oxidation of deuteroferrihaem by H(2)O(2) to bile pigment and CO was studied both by stopped-flow kinetic spectrophotometry and mass spectrometry, at 25 degrees C, I=0.1m. 2. Spectrophotometric studies imply that, at constant pH, the rate of bile pigment formation is first-order with respect to [H(2)O(2)] and also proportional to [deuteroferrihaem monomer]. The effect of pH on the apparent second-order rate constant suggests that acid-ionization of deuteroferrihaem monomer is important in the reaction mechanism. 3. The relative rates of formation of O(2) (from catalytic decomposition of H(2)O(2)) and CO (from oxidation of ferrihaem) have been measured by mass spectrometry. The results are in excellent agreement with those obtained by combining kinetic data for catalytic decomposition (Jones et al., 1973, preceding paper) with the spectrophotometric results for deuteroferrihaem oxidation.

Carbon Monoxide↗
PubMedDate not supplied

Saccharides localized by fluorescent lectins on trophectoderm and endometrium prior to implantation in pigs, sheep and equids.

Pre-implantation blastocysts together with the corresponding maternal endometrium were obtained from pigs, sheep and equids at known stages of pregnancy. Thin sections of fixed tissue were reacted with FITC-labelled conjugates of lectins specific for alpha-L-fucose, N-acetyl-D-glucosamine, D-galactose, N-acetyl-D-galactosamine and alpha-D-manno- and alpha-D-gluco-pyranosyl residues. The pre-implantation blastocysts of both pig and sheep, throughout the period studied, had a continuous reaction for alpha-L-fucose, which has been suggested to be important in compaction and the expression of SSEA-1 antigen in mouse embryos. Reactivity for N-acetylglucosamine appeared in the blastocysts of both pig and sheep prior to implantation. The staining for fucose and acetylglucosamine was restricted to the apical (maternally apposed) aspect of the trophectoderm. No specific reactivity was observed in horse conceptuses; however, discrete regions of endometrial epithelium stained intensely for N-acetylglucosamine, and may represent 'recognition' sites for the implanting embryo.

Animals↗