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Biomedical subjects

C Barber

Publications and source records attributed to C Barber.

At least 19 recordsLinked to original sources
PubMed1989

Dark adaptation compared with electrooculography in primary biliary cirrhosis.

In a series of asymptomatic patients with primary biliary cirrhosis there was a significant impairment of dark adaptation thresholds as compared with a control group. Vitamin A levels were abnormally low in only two of the patients and these two both showed high dark adaptation thresholds. The electrooculogram was reduced in only the most severely affected case. It is suggested that visual function tests should be performed alongside vitamin A level measurements before deciding on treatment.

Adult↗
PubMed1989

Effects of a sedative and of a non-sedative H1-antihistamine on the event-related potential (ERP) in normal volunteers.

Measurements of the amplitude and latency of the P3b component of the event-related potential (ERP), simple reaction time (SRT) and four psychomotor tests (VAS, DSST, DSp and CFF) were made on 12 male subjects (aged 19-24 years) 1.0-1.5 and 4.0-4.5 h after single oral doses of triprolidine (7.5 mg), terfenadine (60 mg) and placebo. Neither triprolidine nor terfenadine changed P3b amplitude or latency although VAS, CFF and DSST scores were significantly altered by triprolidine at 1.0-1.5 h after dosage. These results suggest that the P3b is too robust to reflect the mild sedative properties of an H1-receptor antihistamine, or that H1-receptors are not involved in P3b generation.

Adult↗
PubMed1989

Relative safety of intravenous digital subtraction angiography over other methods of carotid angiography and impact on clinical management of cerebrovascular disease.

Data from a multicentre survey based on three London teaching hospitals on the relative safety and clinical utility of intravenous carotid digital subtraction angiography (DSA) over intra-arterial DSA and conventional carotid angiography are presented. The incidence of stroke during intra-arterial DSA was 0.7% (n = 538) and during conventional angiography was 0.8% (n = 780). The incidence of stroke during intravenous DSA was zero (n = 3710). When it constituted the initial investigation, intravenous DSA achieved a 93.8% replacement value over intra-arterial studies as a whole (n = 474) and 89% replacement value for patients having carotid endarterectomy (n = 99). It was also noted that the installation of DSA equipment at one unit coincided with a sixfold increase in the number of carotid angiographic examinations and an almost threefold increase in carotid endarterectomies.

Angiography, Digital Subtraction↗
PubMed1987

T15 group A streptococcal Fc receptor binds to the same location on IgG as staphylococcal protein A and IgG rheumatoid factors.

Previous work has shown that IgG rheumatoid factors (RF) bind to the C gamma 2-C gamma 3 interface region of human IgG in the same area that binds staphylococcal protein A (SPA). Group A, C, and G strains of Streptococci possess Fc receptors that bind to IgG but not to fragments containing only the C gamma 2 or C gamma 3 domains. This work describes the binding site location on human IgG for the binding of the isolated Fc receptor from the T15 strain of a Group A streptococcus and its relationship to the site that binds SPA and the IgG RF. The isolated T15 Fc receptor (T15) with a molecular mass of 29.5 kD inhibited the binding of IgG RF to IgG. The binding of T15 itself to IgG was strongly inhibited by SPA (42.0 kD) and its monovalent fragment D (7 kD). Human IgG fragments consisting of the C gamma 3 domains did not inhibit the binding of T15 to IgG, whereas those with both domains were effective inhibitors. T15 did not bind to rabbit IgG fragments consisting of either the C gamma 2 or C gamma 3 domains, but did bind to those with both domains. An IgG3 myeloma protein was a poor inhibitor and has been shown to bind poorly to the IgG RF. Most IgG3 myeloma proteins did not bind to SPA. The substitution of Arg and Phe for His 435 and Tyr 436 is responsible for the poor binding of IgG3 to SPA and to the IgG RF. Chemical modification of His or Tyr on IgG reduced its ability to inhibit the binding of T15 to IgG. Reversal of the chemical modifications with hydroxylamine resulted in near complete restoration of inhibitory capacity. This information, collectively, coupled with the known positions in space of the His and Tyr residues in the C gamma 2-C gamma 3 interface region, verified that both His 435 and Tyr 436, and possibly His 310 and 433, are involved. These residues are also involved in binding SPA and the IgG RF. These data therefore indicate that the T15 Group A Streptococcal Fc receptor binds to the same location on the Fc of IgG as SPA and the IgG RF. The biologic relevance of these similarities between bacterial cell wall Fc receptors and IgG RF are not yet apparent, but suggest that RF could bear the internal image of these bacterial structures.

Animals↗
PubMed1986

The pattern evoked response in disorders of the optic nerve.

The pattern evoked electroretinogram (PERG) was investigated in 11 patients with unilateral optic nerve disease and in a series of age-matched controls. The visually evoked potential (VEP) was also measured. The PERG showed a similar reduction to the VEP in optic nerve disease. Serial studies indicate that the PERG may not be affected immediately in some instances but may show a gradual decline over several months.

Adolescent↗
PubMed1986

The prediction of abnormal evoked potentials in schizophrenic patients by means of symptom pattern.

The case notes of 23 schizophrenic patients who participated in a study of somato-sensory cortical evoked responses were examined for descriptions of the clinical features of their mental state at the time of first illness or most recent relapse. A comparison of syndrome scores derived from Present State Examination with those derived from case notes showed that the latter was a reliable method of mental state description for the purposes of this study. A group of syndromes similar to that described in electrodermal research was identified from the case note review and found to be highly correlated with the presence of an abnormal response in the somato-sensory evoked potentials study.

Adult↗
PubMed1985

Stable abnormalities in the lateralisation of early cortical somatosensory evoked potentials in schizophrenic patients.

During the investigation of somatosensory evoked cortical potentials arising from a complex vibro-tactile stimulus to the forefingers, an abnormal lack of lateralisation of response was found in 10 out of 21 schizophrenic patients. Eight patients with severe affective illness all had the expected degree of lateralisation of cortical potentials, as did 12 out of 15 normals. Three normals and 3 schizophrenic patients had a loss of lateralisation of the evoked response on stimulation of one hand but a normal lateralisation on stimulation of the other. The considerable technical problems of this and related techniques are discussed, but it is suggested that further exploration of this technique is justified. At this stage, no conclusion can be drawn about the cause of the abnormalities.

Adolescent↗
PubMed1985

Specific proteins common to Salmonella paratyphi B and C.

A serum prepared with proteins from Salmonella paratyphi C precipitates indiscriminately the proteins from numerous heterologous Salmonellae. After different absorptions, that eliminate all the antibodies induced against common E. coli and Salmonellae determinants, a specific precipitation of a S. paratyphi C protein which is identical with that of an S. paratyphi B protein is evident in agar gel diffusion.

Antibodies, Bacterial↗
PubMed1985

Heterogeneity in the sizes of proteins which diffuse across the outer membrane barrier of bacteria.

Proteins of both small and large molecular sizes diffuse together across the outer membrane barrier of bacterial cells. Once outside, the proteins present in convenient extracts react in agar-gel diffusions against correspondingly antibacterial induced antibodies by precipitation lines that occur at various distances from the wells containing the antigens. The distances between the precipitation lines depend on the velocity with which the proteins are moving in the agar gel; their speed is a result of the molecular sizes of the proteins. The differences involve the intrinsic qualities of the species that synthesize the antigens.

Antigen-Antibody Complex↗
PubMed1981

The absence of introns within a human fibroblast interferon gene.

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.

Base Sequence↗
PubMed1981

Polysaccharides and their common proteinic carrier in the Vi antigens of Citrobacter ballerup and Salmonella typhi Ty2.

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.

Antigens, Bacterial↗
PubMed1980

Complete structure of the hemagglutinin gene from the human influenza A/Victoria/3/75 (H3N2) strain as determined from cloned DNA.

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.

Amino Acid Sequence↗
PubMed1980

Unusual antigenic composition of an Arizona strain.

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.

Agglutination Tests↗
PubMed1980

The mosaic of proteins synthesized by Salmonella typhimurium.

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.

Animals↗
PubMed1979

Complete nucleotide sequence of an influenza virus haemagglutinin gene from cloned DNA.

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.

Amino Acid Sequence↗
PubMed1979

Salmonella choleraesuis proteins and their relation to proteins from bacteria of heterologous sero-groups.

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.

Animals↗
PubMed1979

Discrepancies Between strong immunochemical relations of S. typhimurium and S. kentucky and their behaviour "in vivo".

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.

Animals↗