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Biomedical subjects

J C Booth

Publications and source records attributed to J C Booth.

At least 19 recordsLinked to original sources
PubMed1991

Threshold integration of bi-amplitude signals.

This study examined the pattern of intensity integration at threshold. The stimuli studied are unique in that they have a compound peak-to-peak amplitude envelope. This waveform was partitioned into two segments, each having a different peak-to-peak magnitude (bi-amplitude). All signals in the bi-amplitude series were the same duration (100 ms). Therefore, threshold differences between these signals are due solely to the integration of intensity in the amplitude dimension. A prediction of the pattern of thresholds, based on the diverted-input hypothesis, suggested that little or no integration would occur when the amplitude difference between segments is greater than a specific magnitude. Our results indicate that there are similarities in the integration process found with variable duration signals and with bi-amplitude signals. We conclude that previous estimates of the minimum intensity level based on temporal integration data underestimates the intensity levels that can contribute to threshold. Our results suggest that there are no apparent constraints on the intensity levels that can be integrated near threshold. The auditory system integrates distributed stimulus intensity in both the time and amplitude dimensions. Temporal integration in the auditory system can be viewed as a signal process, where an enhanced internal representation is given low-level stimuli.

Acoustic Stimulation↗
PubMed1991

Sequence analysis of the V3 loop regions of the env genes of Ugandan human immunodeficiency proviruses.

Ugandan strains of human immunodeficiency virus type 1 (HIV-1) were isolated by cocultivation of peripheral blood lymphocytes from infected individuals with cord blood lymphocytes. Sequences from the V3 region of the env gene were amplified by the polymerase chain reaction (PCR) from chromosomal DNA obtained from low passage virus cultures. The PCR products from 13 Ugandan isolates were cloned into a phagemid vector and sequenced. Many isolates contained divergent V3 loop sequences and adjacent regions: diversity was associated with codon deletions or duplications and with nucleotide substitutions, especially G----A transitions. Proviruses from some of the cultures showed extensive diversity within the V3 loop sequences but others were more homogeneous. The V3 loop apices were conserved in 6 of the Ugandan proviruses and these were very similar to the equivalent regions of several Zairean proviruses. The V3 loop apices of African isolates of HIV-1 are divergent from those of North American isolates. The possible biological consequences of this divergence are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Complement-independent neutralising monoclonal antibody with differential reactivity for strains of human cytomegalovirus.

A mouse monoclonal antibody with complement-independent neutralising activity against cytomegalovirus (CMV) and reactive with the 86 kilodalton (kDa) viral glycoprotein H is described. Neutralisation tests against a range of different strains of CMV showed significant crossreactivity, but clear differences were evident between the two prototype viruses AD169 and Davis, and particularly between AD169 and several low-passage recent clinical isolates; CMV present in urine was neutralised weakly if at all.

Animals↗
PubMed1989

Discordant results obtained on testing sera from immunocompromised patients for cytomegalovirus IgG by enzyme-linked immunosorbent assay and radioimmunoassay.

The investigation of sera from immunocompromised patients for antibody to CMV by ELISA, RIA, immunofluorescence (IF) and complement-fixation (CF) revealed discrepancies that reflected differences in test specificity rather than sensitivity and suggested that for the long-term serological follow-up of such patients it would be advisable not to rely on only a single assay procedure.

Adult↗
PubMed1988

Complement-mediated cytolytic activity associated with cytomegalovirus complement-fixing IgM antibody.

Cytomegalovirus-specific complement-fixing IgM (CMV CF-IgM) antibody was detected in 12/84 (14.3 percent) sera containing CMV-specific IgM. Higher titres were obtained by using a purified antigen preparation containing enveloped virus particles and membrane fragments when compared with a crude extract of infected cells, suggesting that the CF component of CMV IgM reacts predominantly with antigens on the surface of the infected cells. This also accounts for its complement-mediated cytolytic activity. Neither CMV-specific non-complement-fixing IgM nor CMV-specific IgG demonstrates cytolytic activity.

Antibodies, Viral↗
PubMed1988

Functional studies of cell-mediated immunity in haemophilia and other bleeding disorders.

Defects of immunoregulation which occur in haemophilia, reflected by numerical changes in T lymphocyte subsets, have been further investigated in functional studies. Polyclonal T-cell activation by the mitogen phytohaemagglutinin (PHA) and specific stimulation by cytomegalovirus (CMV) or herpes simplex type 2 (HSV-2) in previously sensitized subjects were studied in peripheral blood lymphocyte and in T4-cell-enriched cultures. Compared with 12 controls, the responses of 11 patients (nine with haemophilia A and two with von Willebrand's disease) to PHA were significantly reduced both in unfractionated and in T4-cell-enriched peripheral blood lymphocyte cultures. Reduced responses to PHA were found in HIV (HTLV III)-seronegative as well as -seropositive patients. There were no significant differences between the response of patients' unfractionated and T4-enriched peripheral blood lymphocytes to CMV/HSV-2 recall antigen and the control subjects, although there was evident variation in the magnitude of patients' unfractionated and T4-enriched lymphocyte responses.

Antigens, Viral↗
PubMed1987

Lymphocyte transformation test responses to cytomegalovirus in healthy adults from Britain and Iraq.

Lymphocyte transformation tests to CMV were carried out on young healthy adults from Britain and Iraq. Positive results were obtained in all of 28 seropositive British subjects as compared to 17 of 33 (51.5%) seropositive Iraqis; moreover, stimulation index values in the British group (mean 11.58) were significantly higher than in the Iraqi group (mean 2.84). Attempts to relate these differences to demographic characteristics, antibody response to CMV, including the response to early antigens, lymphoproliferative response to herpes simplex virus, and to phytohaemagglutinin and the presence of blocking factors were unrewarding.

Adolescent↗
PubMed1986

Increased sugar transport in BHK cells infected with Semliki Forest virus or with herpes simplex virus.

Infection of BHK cells by SFV increases the rate of uptake of [3H]MeGlc and of [3H]dGlc at approximately 2 hours p.i. Infection by HSV increases the uptake of [3H]MeGlc and [3H]dGlc at approximately 10 hours p.i.; the increased uptake is prevented by acyclovir. It is concluded that an increased sugar uptake by infected cells reflects an increased rate of transport across the plasma membrane and is the result of cellular changes caused by virus infection.

3-O-Methylglucose↗
PubMed1986

Altered acoustic cue discrimination in Broca's and conduction aphasics.

The present investigation explored the acoustic cue discrimination abilities of eight Broca's and four conduction aphasic patients and nine normal controls. A word-discrimination test was used to assess the subjects' ability to discriminate selected acoustic cues for distinctive features of phonemes. The words differed from one another by a selected minimal feature, such as stop-gap duration, duration of fricative noise, direction and extent of final format transition, or relative location of friction noise in the spectrum. Results indicated that performance for normal and aphasic subjects was poorer for altered temporal subtest items than for altered spectral subtest items. Within the spectral subtest, fewer Broca's aphasics than conduction aphasics passed the items, while 90% of the normals passed. Within the temporal subtest, fewer conduction aphasics than Broca's aphasics passed the items, while 75% of the normal subjects passed this subtest. The results support previous research suggesting that deficiencies in auditory processing of selected acoustic cues are not limited to Wernicke's aphasic individuals but may be found to a varying degree in several aphasic groups.

Adult↗
PubMed1986

Coxsackie B virus-specific IgM antibody and myocardial infarction.

The ELISA technique was shown to be group-specific for the detection of IgM antibodies against coxsackie B viruses, and probably against a wider range of enteroviruses. No evidence was obtained that recent coxsackie B-virus infection predisposes to myocardial infarction.

Antibodies, Viral↗
PubMed1978

Syncytium formation caused by human cytomegalovirus in human embryonic lung fibroblasts.

Large syncytia were regularly produced after prolonged infection in vitro of human embryonic fibroblasts by AD169 and other strains of human CMV. The syncytia showed typical CMV intranuclear inclusion bodies and herpesvirus particles in the nuclei and cytoplasm. It is proposed that syncytium formation follows abortive infection of the fibroblasts with defective virus.

Capsid↗
PubMed1978

Dose-response relationships in a microneutralization test for foot-and-mouth disease viruses.

Two-dimensional quantal microneutralization tests on foot-and-mouth disease viruses, in which neutralizing antibody activity was titrated against a serial range of virus doses, demonstrated a variety of dose-response curves some of which were rectilinear, others clearly curvilinear. Moreover, in the case of the non-linear responses obtained with some antisera, the shape of the curve was such that antibody titres recorded with doses of virus ranging from 10(3)-10(5) TCD50 were closely similar. Studies were carried out on the effect of varying the conditions of the test on the shape of the dose-response curve: significant differences were obtained after treatment of the antiserum-virus mixtures with anti-species globulin, and when the test was assayed in cells of differing susceptibility to infection.

Aphthovirus↗
PubMed1978

Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains.

A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.

Aphthovirus↗
PubMed1977

Enhancement by diethylamineothyl-dextran of the plaque-forming activity of foot-and-mouth disease virus-antibody complexes in pig kidney IB-RS-2 cells.

Mixtures of foot-and-mouth disease (FMD) virus and homologous antibody, assayed for surviving plaque-forming units (PFU) in pig kidney IB-RS-2 cells, demonstrated an average ten-fold greater recovery of infectivity when diethylaminoethyl-dextran (DEAE-dextran) was included in the overlay medium. This enhancement, which was not detected in baby hamster kidney BHK21 cells, was due to the ability of the polycation to potentiate attachment of virus-antibody complexes to the IB-RS-2 cells. In some instances the effect was so pronounced that the plaque-forming activity of virus in the presence of homologous antibody exceeded that of virus alone.

Animals↗
PubMed1977

Neutralization kinetics studies with type SAT2 foot-and-mouth disease virus strains. 1. Factors that influence the rate and pattern of neutralization.

A study of the kinetics of inactivation of foot-and-mouth disease virus type SAT 2 strains revealed that in most cases the rate of neutralization was not rectilinear. Deviations from first-order kinetics observed represented biphasic or parabolic and stepwise reactions. The initial rate was rapid and showed no lag phase or shoulder. The effects of deviations from linearity could be minimized by dilution of antiserum to a suitable extent. Treatment of virus-antibody mixtures with anti-species globulin resulted in enhancement of the rate of neutralization of homologous and heterologous reactions without significantly altering the relation between the two. This treatment also considerably reduced the amount of the persistent fraction. In attempt to disaggregate virus it was observed that sodium dodecyl sulphate inhibited neutralization of virus by specific antiserum.

Antibodies, Anti-Idiotypic↗
PubMed1977

Neutralization kinetics studies with type SAT 2 foot-and-mouth disease virus strains.

A comparison of homologous and heterologous rates of neutralization demonstrated that antigenic relationships of foot-and-mouth disease virus strains could be differentiated quantitatively by the kinetics of neutralization method described previously (Rwysed this way gave R values which were similar to those obtained with other neutralization test methods but which were generally smaller than those obtained with complement fixation test results. It was demonstrated that there were wide differences between the vaccine strains tested as demonstrated by R value relationships. An examination of r values, however, demonstrated that antisera to the Moz 1/70 strain were highly reactive with most of the virus strains from Central and Southern Africa. The selection of FMD virus strains with a wide serological range for vaccine production is discussed.

Animals↗