Biomedical subjects
Publications and source records attributed to C Barber.
Reassessment of the antigens involved in the cross-relation of Enterobacteriaceae point to the common proteins first discovered by White (1932) and named substance Q. All the serological characteristics of substance Q, as described by White, are identical with those obtained with pure enterobacterial proteins.
Experiments in which immobilised restriction fragments of genomic DNA were hybridised with a cloned human fibroblast interferon cDNA indicate that the homologous chromosomal genes exist in only one basic arrangement. This is in marked contrast to recent studies by Nagata et al. (1) showing that there are at least eight gene arrangements for human leukocyte interferon. Having isolated a chromosomal human fibroblast interferon gene from a gene bank, we conclude from nucleotide sequencing studies that there is a complete absence of introns within the RNA-coding region. In view of a similar observation recently made for a human leukocyte interferon gene (1), it would appear as if interferon genes in general are unlike the vast majority of eukaryote genes in this respect.
The inherent stimulus characteristics of three common types of visual stimulus systems, based upon a slide projector, a television and a photic stimulator, were measured. The effect of these characteristics upon pattern visual evoked potentials (VEPS) elicited by the systems was also investigated. Considerable differences in both spatial and temporal luminance characteristics were found between the systems. The differences in spatial luminance properties produced no significant changes in the VEP waveform, but the temporal luminance properties of the television system, in particular, produced maleficent effects on the VEP. Methods of dealing with these problems and of overcoming some of the traditional disadvantages of a strobe stimulus are discussed.
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Immunochemical analysis of Citrobacter ballerup and Salmonella typhi Ty2 showed that the strains share native and heat-resistant proteins that are, apparently, the carriers of a common polysaccharidic determinant present in their respective somatic antigens. After the classic acetic acid hydrolysis, the somatic antigen of C. ballerup reacted, in agar gel, against the homologous antiserum by two precipitation lines, one of which also precipitated against the anti S, typhi Ty2 serum; the hydrolysis of the S. typhi Ty2 somatic antigen demonstrated that, in addition to the 'O' polysaccharide, reacting against all the S. typhi antisera, it contains a polysaccharide that precipitated against the anti-C. ballerup serum. The elusiveness in the agglutinability of only freshly isolated bacterial authorizes some doubt concerning the responsibility of the antipolysaccharide antibodies in the agglutinating Vi sera; in order to induce anitpolysaccharides hyperimmunizations are needed while antiproteins are easily induced by short immunizations.
The synthesis by Enterobacteriaceae grown on artificial media of proteins, with a diversity of specificities previously found with the help of antiprotein sera, is confirmed with antibacterial sera prepared with species belonging to different serogroups. An earlier recognition of the existence of these materials was hindered by the devised schemes of classification and the claims relating 'O' factors to the bacterial polysaccharides. The synthesis, on artificial media, of mixtures of heterologous proteins by all the analysed species is no proof that their behaviour in vivo is identical; notwithstanding their high amounts in the mixtures, few of the heterologous proteins are involved in cross-protection of a host against its natural pathogen.
The complete sequence of a hemagglutinin (HA) gene of a recent human influenza A strain, A/Victoria/3/75, is 1768 nucleotides long and contains the information for 567 amino acids. It codes for a signal peptide of 16 amino acids, the HA1 chain of the mature hemagglutinin of 329 amino acids, a connecting region between HA1 and HA2 consisting of a single arginine residue and the HA2 portion of 221 amiino acids. The sequence is compared with the hemagglutinin of two members of other subtypes, the human H2 strain A/Jap/305/57 and the avian Hav1 strain A/FPV/Rostock/34, and with one of the same H3 subtype, A/Memphis/3/72. To align the HA1 chain of different major subtypes several deletions/insertions of single amino acids must be invoked, but two more extensive differences are found at both ends, one leading to an extension of the amino terminal sequence of HA1 and the other (four residues) occurring in the region processed away between HA1 and HA2. Comparison of the HA1 of two H3 strains suggests that drift probably depends on single base mutations, some of which change antigenic determinants. The HA2 region, which apparently is not involved in the immune response, is highly conserved even between different subtypes, and single base substitutions account for all the observed diversity. A hydrophobic segment of 24 residues is present in the same position close to the carboxyl terminus of HA2 in both Victoria and FPV, and presumably functions in implantation into the lipid bilayer. The many conserved features not only in HA2 but also in HA1 suggest a rather rigid architecture for the whole hemagglutinin molecule.
A wide variety of formulated liquid diets are currently available on the Canadian market. Used for oral and tube feedings, they are nutritionally complete diets when offered as the sole source of nourishment for patients who are unable or unwilling to take solid food. To assist dietitians in identifying formulas most suited to patients' requirements, products are listed according to nutrient composition, caloric density, osmolality and packaging.
The immunochemical analysis of Arizona strain 23:23:30:42 displayed a peculiar antigenic composition. Hyperimmune sera prepared in rabbits with formaldehyde-treated bacteria precipitated, in agar-gel, the proteins from numerous Salmonellae and E. coli by homogenous lines of apparent serological identity with the Arizona proteins. The reactions were unilateral. The proteins from Arizona did not react against the heterologous antibacterial sera tested; they precipitated, however against sera, rich in common antibodies, that were prepared with proteins from Salmonellae and E. coli. The genetic architecture of this Arizona's chromosome is, apparently, responsible for the unusual antigenic composition of the strain as exhibited by the immunochemical analysis of its hyperimmune serum.
A profusion of proteins with heterologous serological specificities was synthesized by S. typhimurium grown on artificial media; accordingly, sera prepared in rabbits with these proteins displayed an abundance of antibodies reacting, in agar gel, against numerous heterologous proteins. the absorption of the sera with different Enterobacterial proteins proved that the S. typhimurium proteins are a mixture of specific proteins, and common E. coli and Salmonellae determinants; in addition, a group of strongly cross-precipitating proteins common to S. typhimurium and S. choleraesuis and to S. typhimurium and S. kentucky were identified that were not present in the proteins common to S. enteritidis, S. typhi and E. coli, or in the S. paratyphi A proteins used absorptions. The specific proteins of S. typhimurium were synthesized on artificial media in, apparently, smaller amounts than the common proteins; their role in the protection of mice against infection with their natural pathogen was, however, proof of their specificity and contrasted with the ineffectiveness, in protecting the mice, of the common proteins.
The mosaic of proteins synthesized by S. typhi, S. enteritidis and E. coli, induced in immunized rabbits corresponding antibodies that precipitated almost indiscriminately numerous heterologous antigens. Antibodies induced against eventual specific antigens could not be identified unless the sera were absorbed with heterologous proteins. The comparative immunochemical analysis of the total and absorbed sera proved that the proteins from E. coli are mixed with proteins sharing Salmonella specificities while E. coli proteins are present in the mixtures of proteins isolated from S. enteritidis and S. typhi. The absorption of anti S. typhi sera with proteins from different E. coli serotypes, removed a large amount of antibodies, leaving free for reaction those induced against Salmonellae common proteins. The absorption of the anti S. typhi sera with proteins from S. enteritidis eliminated the totality of preciptating antibodies meaning that no specific antibody was induced in the sera of animals immunized with S. typhi proteins. In contrast, the S. enteritidis proteins induced antibodies against a specific S. enteritidis protein, in addition to numerous heterologous determinants; the existence of the specific antibody was evident in all the absorbed sera, notwithstanding the eventual relationship with the heterologous absorbing proteins. Absorptions of the antisera to proteins from E. coli with proteins from either S. typhi or S. enteritidis removed the antibodies induced against the absorbing proteins leaving free for reactions antibodies for the specific E. coli proteins. As the behaviour in vivo of the human pathogen is quite different form that of E. coli or S. enteritidis, the absence of a specific antigen in the material synthesized by S. typhi grown on artificial media provides an explanation for the inefficacy of vaccinations with killed S. typhi.
Comparative agar-gel diffusions of sera to proteins from E. coli O 126 and from S. enteritidis and samples of the sera absorbed with heterologous proteins proved that all were mixtures of antigens with specificities of common Salmonellae and E. coli. The absorption of the E. coli serum with proteins from S. typhi removed the smallest amont of antibodies while absorption with proteins from S. enteritidis removed common antibodies resembling those eliminated by absorption with heterologous E. coli proteins. Similar results were obtained by the opposite absorption of the S. enteritidis serum with the E. coli O 126 proteins; it is apparent from the results that S. enteritidis and E. coli have in their composition mixtures of strongly related proteins sharing determinants for both species. An added confirmation of these findings was obtained by absorbing the E. coli serum with proteins from S. paratyphi A; the absorption removed antibodies induced against proteins from numerous E. coli and Salmonellae strains. A determinant common to all the E. coli and Salmonellae - that is apparently situated on the E. coli coli proteins - is still reacting by a thin precipitation line against all the antigens and is evident in all the E. coli absorbed sera.
A synthetic fowl plague virus (FPV) haemagglutinin gene has been cloned in bacteria and the complete sequence of the RNA gene deduced. It is 1,742 nucleotides long and the mRNA codes for 56.3 amino acids in an uninterrupted sequence. The nature of some of the important domains in the haemagglutinin has been established, and their structure is discussed in relation to their function. Extensive amino acid sequence homologies exist between FPV and human influenza haemagglutinins.
A diversity of proteins was identified in the material isolated from S. choleraesuis with the help of sera prepared in rabbits with this material. The sera displayed, in agar-gel diffusions, numerous superimposed precipitation lines against proteins from: Salmonellae, Shigellae and E. coli. In contrast to proteins from S. paratyphi C, sharing identical identical 'O' 'factors, the serological activity of the S. choleraesuis proteins was impaired by heating. The immunochemical analysis of the sera before and after exhaustive absorptions with heterologous proteins exhibited a stronger relation of S. choleraesuis with S. thyphimiurium and S. Newport than with S. paratyphi C. The antibodies induced against free proteins with S. paratyphi C specificity, present in the mosaic of proteins isolated from S. choleraesuis, were removed by the respective absorption without substantial modifications of the homologous precipitation. In contrast, the absorption of the serum with proteins from either S. newport or S. typhimurium removed almost all the homologous induced antibodies. The strong relations found among species belonging to different serogroups underline the non-conformity of the empirical established serofactors.
Proteins from S. typhimurium and from S. kentucky strongly cross-precipitated against sera prepared in rabbits with the respective strains; agglutinations paralleled the precipitations. The related antigens were, however, not involved in "in vivo" cross-protections. Mice immunized with proteins from S. kentucky resisted the toxicity of the homologous strain and that of a concentration of S. emek which killed the controls but did not survive the infection with 1LD100 of S. typhimurium. There was a long delay in the death of those mice infected with S. typhimurium while the mice immunized with S. typhimurium proteins were killed by the toxicity of 1LD100 S. kentucky, like the controls, within 20 hours. The results strikingly underline the specificity of host-parasite relations and the need for circumspection when involving common antigens in either virulence or toxicity.
A mosaic of proteins is synthesized by each of the Enterobacterial species grown on artificial media (tryptose-agar, Difco). Their existence was proven with the help of sera prepared in rabbits with proteins from: S. enteritidis, S. typhi, S. typhimurium, S. paratyphi C, E. coli, and Sh. sonnei. The induced antibodies, strongly precipitated numerous heterologous Enterobacterial proteins. The proteins of Sh. dysenteriae 4, although reacting against the heterologous sera, were poor immunogens and induced, mainly, homologous antibodies. Comparative agar-gel diffusions of the same proteins against the antiproteinic sera and corresponding antibacterial sera proved that the bacteria induced fewer antibodies against a reduced number of heterologous antigens. Thus, it is evident that a competition among the numerous antigens of a bacterium takes place when whole bacteria are used for immunizations. The differences in the degree of relatedness of Salmonellae, Shigellae, and E. coli are illustrated by their reactions in agar-gel against homologous and heterologous sera. The serological activity of heated proteins (1 hr at 100 degrees C) against the antiproteinic sera differed according to the intrinsic qualities of the analysed materials.
Ribosomal 5S 32 P-labelled RNA was isolated from imbibing wheat embryos and digested with nuclease S1, a single-strand specific nuclease. The products of enzymic digestion were separated by polyacrylamide gel electrophoresis and identified by fingerprint analysis of their RNase T1 digestion products. The results indicate that the most sensitive portion of the molecule, and hence, the region containing the least helical structure, is close to the 5'-terminus. Similarly, the most resistant portion of the molecule is close to, but does not include, the 3'-terminus. These findings are discussed in relation to proposed models for the secondary structure of 5S RNA.
The proteins from S. virginia, with the sole 8 "O" factor, precipitated against homologous and related heterologous sera by a conspicuous, homogenous line of serological identity, with proteins from: S. newport (6.8), S. blockley (6.8), S. emek (8.20). The proteins, however, were not involved in the bacterial agglutinations since the absorptions, which removed the common precipitins from the sera, did not modify the homologous agglutinations. The results with anti-S. newport and anti-S. blockley sera sharing identical "O" factors while displaying different immunochemical compositions as well as the strong immunochemical relations found between S. virginia and S. newport belonging to the different subgroups C2 and C3 underline the non-relatedness of agglutinins and precipitins.