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Biomedical subjects

C J Burrell

Publications and source records attributed to C J Burrell.

At least 91 records · Page 5Linked to original sources
PubMed1983

Hepatitis B reservoirs and attack rates in an Australian community. A basis for vaccination and crossinfection policies.

Four different subpopulations in South Australia, which were expected to have high rates of hepatitis B infection (Asians, Aboriginals, homosexual men, and drug addicts) were examined for their contribution to the total reservoir of hepatitis B surface antigen (HBsAg) carriers and to the total annual incidence of acute hepatitis B infection in South Australia. Age-specific prevalence data were also examined to assess the ages at which infection is commonly acquired. It was found that the above four groups, which comprise 3% of the State's population, are likely to include about 75% of HBsAg carriers in the State, but contribute a minority of the total new infections each year; they are not likely to present a significant risk of infection to the community at large. Three different age-related patterns of acquisition of infection were recognized--among Southeast Asians and Aboriginals, homosexual men and drug addicts, and the general community, respectively. The above approach, and to some extent the general findings, should be applicable to other similar communities in the formulation of effective policies for the control and prevention of hepatitis B infection.

Adolescent↗
PubMed1983

Patterns of single- and double-stranded hepatitis B virus DNA and viral antigen accumulation in infected liver cells.

Liver sections from five patients with persistent hepatitis B virus (HBV) infection and active cirrhosis were shown to contain intracellular HBV DNA by in situ hybridization using cloned 3H-labelled HBV DNA probes. Two classes of infected cells, with different distributions throughout the liver, were distinguished: (i) cells containing a low copy number of double-stranded HBV nucleotide sequences, confined to the cell nucleus and thought to represent HBV DNA, and (ii) cells containing large amounts (estimated to be greater than 10 or 15 genome copies per cell) of HBV DNA, much of it in a single-stranded form and largely confined to the cell cytoplasm; these single-stranded regions represented widely separated regions of the HBV genome, in contrast to the structure of the DNA in mature virions. It is likely that these latter cells may be supporting viral DNA synthesis. Cells with large amounts of cytoplasmic HBV DNA invariably contained hepatitis B surface antigen (HBsAg) and in addition contained either no detectable hepatitis B core antigen (HBcAg), or cytoplasmic HBcAg or nuclear HBcAg in that order of frequency. Cytoplasmic HBcAg was highly predictive of the presence of large amounts of cytoplasmic HBV DNA in the same cell, while either nuclear HBcAg, or cytoplasmic HBsAg, were often seen both in cells with and without such levels of DNA. These patterns, relating HBV DNA and antigen content in naturally occurring asynchronous infection in a heterogeneous cell population, should provide a background to further studies of the virus replication cycle with a defined experimental system, when such a system becomes available.

DNA, Single-Stranded↗
PubMed1981

Detection of hepatitis B virus DNA sequences in infected hepatocytes by in situ cytohybridisation.

Plasmid pHBV 114 DNA, which contains 73% of the genome of hepatitis B virus (HBV), was radiolabelled with tritium to 1-2 X 10(8) dpm/microgram by nick translation and used as a radioactive probe to detect HBV DNA present in sections of infected liver tissue by in situ hybridisation followed by autoradiography. Factors affecting the sensitivity of the reaction were examined, including different methods of fixation, hybridisation time, temperature, and buffers. The specificity of the reaction for detecting viral DNA was carefully established by the use of unrelated DNA probes, pretreatment of sections with DNAase, and comparing the stability of the binding of DNA probe at different temperatures, with the melting curve of double-stranded DNA in solution. In the one liver studied in detail, cells containing large amounts of viral DNA were distributed in foci corresponding to areas containing morphologically damaged hepatocytes. This observation suggested a relationship between active viral replication and cell damage. Viral DNA was found mainly in the cytoplasm, although a minority of nuclei in these foci were also positive.

Autoradiography↗
PubMed1980

Serological markers of hepatitis B infection.

Tests currently available or under development for the various markers of HBV infection have allowed a description and classification of different responses to infection. To be of maximum value in assessing the stage and prognosis in virological terms, consecutive samples from an individual are required. Although well over 90 per cent of blood donations capable of transmitting infection can be presumptively identified and witheld, no reliable, sensitive, direct measures of infectivity are available routinely.

Carrier State↗
PubMed1979

Hepatitis Be antigen and antibody in hepatitis B surface antigen positive blood donors.

In a study of 105 asymptomatic HBsAg positive blood donors, 9 (8.6%) were found to have HBeAg, 38 (36.2%) anti-HBe, and the remaining 58 (55.2%) neither marker detectable by gel diffusion. There was no correlation between HBeAg/anti-HBe status and HBsAg sub-types, Glm allotypes, the presence of anti-Gm, red cell antibodies, or rheumatoid factor. Rheumatoid factor activity could be removed from anti-HBe positive sera without removing anti-HBe activity, indicating that separate entities were involved. HBeAg was found only in donors under the age of 30 (P less than 0.005), while anti-HBe did not show an age-related trend. HBeAg was also found less commonly in donors of blood group A than in the total carrier population (P less than 0.05), indicating an apparent protection in carriers of group A. The blood group distribution for the 105 HBsAg positive donors was similar to that of the general population.

ABO Blood-Group System↗
PubMed1978

Rapid detection of hepatitis B surface antigen by double antibody radioimmunoassay.

HBsAg and anti-HBs can be detected by double-antibody radioimmunoassay in a reliable routine overnight assay of sensitivity approaching that of solid-phase immunoradiometric assay. The test requires careful standardisation and regular preparation of I125-HBsAg of appropriate quality, but otherwise uses only small quantities of commercially available reagents. In this paper, the reaction kinetics of the first incubation (test sample + limiting amount of rabbit anti-HBs), second incubation (reaction mixture + I125 -HBsAg) and precipitation reaction (reaction mixture + antirabbit globulin) were examined, to determine the minimum time required for the assay compatible with adequate sensitivity and user convenience; in addition, in order to reduce the time of radioactive counting, the maximum amount of I125-HBsAg per test compatible with a satisfactory assay was examined. It was concluded that, by terminating each reaction before equilibrium was reached, results could be obtained in 2--3 hours with a detection limit similar to the standard overnight procedure. To allow routine examination of large numbers of samples, the possibilities of complete automation of this liquid-phase type of assay were discussed.

Hepatitis B Antibodies↗
PubMed1978

Antibody to hepatitis B surface antigen in haemophiliacs on long-term therapy with Scottish factor VIII.

Thirty-five patients with haemophilia A were studied clinically and serologically between 1971-2 and 1975-6 for evidence of hepatitis B infection. One patient suffered from clinical hepatitis B, and a further eight patients showed antibody responses to hepatitis B surface antigen (HBsAg) consistent with exposure to HBsAg during this period. No evidence for HBsAg exposure was found in 14 patients, while the remaining 12 patients had high titres of antibody to HBsAg at both times and no inferences could be drawn about HBsAg exposure. All patients had received exclusively replacement factor VIII material prepared locally from HBsAg-screened voluntary Scottish blood donations. From the details of the therapy given we calculated that the rate of HBsAg seroconversion in these patients represented about 0.3 HBsAg-containing donations/1000 donations.

Antibodies, Viral↗
PubMed1977

Prevalence of antibody to hepatitits B surface antigen among staff in an Edinburgh hospital.

Antibody to hepatitis B surface antigen was detected by radioimmunoprecipitation in 74 (5-5%) of 1336 staff members in a large general hospital in Edinburgh, in 14 (2-9%) of 480 volunteer blood donors in the area, and in 12 (6-1%) of 197 pregnant women attending for the first time at the ante-natal clinic in the hospital. Rates of antibody prevalence rose with age in the sample of hospital staff and in that of the blood donors, particularly among males. On the other hand, in the ante-natal patients antibody prevalence declined with age. The rates in hospital staff were higher than those in blood donors of comparable age and sex, and high titres of antibody were more common in the staff group. However, no association was found between antibody prevalence and a history of clinical hepatitis, blood transfusion, or recognized contact with cases of hepatitis. Staff who had previously worked in an infectious disease hospital did not show increased antibody prevalence, indicating that simple isolation measures have been adequate to minimize exposure to hepatitis B. No particular prevalence of infection was seen in physicians and surgeons, in the nursing staff, or in workers in clinical diagnostic laboratories, hospital administration or other areas. One group clearly showing increased antibody prevalence was staff currently working, or who had worked, in the Haemodialysis Unit; this correlated with the outbreak of dialysis-associated hepatitis in 1969--70. However, no evidence suggested that significant dissemination of infection had occurred to other defined groups of hospital staff. Elevated rates were also observed in a small sample of kitchen and portering staff, and in obstetric medical and nursing staff; the latter observation indicate a need for further investigation to identify unsuspected exposure to hepatitis B virus.

Adolescent↗
PubMed1976

Tryptic cleavage of antibody binding sites from hepatitis B surface antigen particles.

The sedimentation of radiolabelled 22 nm hepatitis B surface antigen particles was unaffected by treatment with either trypsin or SDS alone, but combined treatment disrupted the particulate nature of the radiolabelled material. Considerable antibody binding activity by the group-specific determinant (a) was preserved after combined SDS and trypsin treatment but was released from the bulk of the radiolabelled protein; gel filtration indicated an approximate mol. wt. of 5000 to 15000 for the released antibody binding material. This material was precipitated by concanavalin A, suggesting the presence of carbohydrate. Its serological activity was remarkably resistant to boiling and to proteolytic digestion, but was partially sensitive to treatment with 0-01 M-periodate or with mixed carbohydrases and neuraminidase, and was greatly reduced by treatment with reducing agent. These data suggest that the stability of the a determinant is due to the structure of the antibody binding site itself, rather than to involvement in the quaternary structure of the particle, and that intact disulphide bonds and carbohydrate, closely related to the antibody binding site, are necessary for the full expression of serological acitivity.

Binding Sites, Antibody↗
PubMed1976

Examination of the polypeptides of hepatitis B surface antigen.

When the polypeptides of hepatitis B surface antigen were examined by SDS-polyacrylamide gel electrophoresis under a variety of conditions, anomalous results were found to be due to (i) variable and at times incomplete dissociation of polypeptides after boiling with 1% SDS and reducing agent, (ii) reaggregation of solubilized material under certain electrophoretic conditions and during laboratory manipulations, and (iii) the variable presence of additional components in hepatitis B surface antigen prepared from certain individual donors. When these factors were taken into account, two major components were consistently identified by discontinuous buffer polyacrylamide gel electrophoresis, of apparent mol. wt. 60000 to 70000 and 12000 to 14000. However, in view of the demonstrated limitations of this technique in examining HBsAg polypeptides, alternative methods are necessary to confirm the true mol. wt. of the unique virus-specified amino acid sequence present.

Electrophoresis, Polyacrylamide Gel↗
PubMed1975

Host components in hepatitis B antigen.

Purified [125I]-labelled 20 to 25 nm hepatitis B antigen particles were found to give low affinity immunoprecipitation reactions with antisera to several normal serum components, which were immunologically distinct from the reaction due to the classical hepatitis B antigen surface determinant. These additional antigenic determinants were acid-stable and tightly bound to the particles; they could not be released by treatment with Tween 80 or ether, but were removed by protease digestion with the preservation of particle integrity. It was not possible to distinguish whether they were due to the presence of trace amounts of partly denatured serum components, or to a weak cross-reaction with antigens present in normal serum. The implications of this finding for hepatitis B antigen and antibody detection in sensititive assays are discussed. No evidence was found for native antigenic material, present in normal serum or normal liver cells, being integral to the structure of these particles.

Bromelains↗