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Biomedical subjects

S A Locarnini

Publications and source records attributed to S A Locarnini.

At least 73 records · Page 4Linked to original sources
PubMed1983

Characterization of a precipitating antigen detected in the serum of patients with viral hepatitis.

During a search for the aetiological agent of non-A non-B hepatitis, a precipitating antigen was detected in the sera of some patients during the acute phase of their illness. The antigen was detected by agar gel diffusion using antibody from convalescent sera obtained from patients with non-A non-B hepatitis, and from haemophiliac sera. The antigen was usually detected early in the patient's illness, disappearing as liver function tests returned to normal. In some patients specific antibody appeared during the convalescent phase of the disease. The antigen does not appear to be specific for non-A non-B hepatitis, as it could be detected with similar frequency in patients with hepatitis A or hepatitis B and some patients with other liver disorders. Biochemical and biophysical studies suggest that the antigen is probably an abnormal lipoprotein produced as a result of acute liver damage.

Antigens↗
PubMed1983

Monoclonal antibodies against hepatitis A virus.

Three monoclonal antibodies (K2-4F2, K3-2F2, and K3-4C8) of the immunoglobulin G2a class were raised against hepatitis A virus. The specificity of these antibodies was confirmed by immune electron microscopy, solid-phase radioimmunoassay, and in vitro neutralization in cell culture. Binding studies suggested that they all recognize closely related antigenic determinants. These monoclonal antibodies should prove to be of great value as diagnostic and research reagents.

Animals↗
PubMed1983

Taxonomic classification of hepatitis A virus.

Sufficient data have accumulated to permit the ICTV Ad Hoc Study Group on the Taxonomy of Hepatitis Viruses to recognize hepatitis A virus as a picornavirus. Within the family Picornaviridae, hepatitis A virus closely resembles members of the genus Enterovirus.

Enterovirus↗
PubMed1982

Biophysical and biochemical characterization of hepatitis A virus.

Biophysical and biochemical analysis of hepatitis A virus has shown it to be a 27- to 32-nm icosahedral particle with 32 capsomers. The mature virion has a buoyant density of 1.33-1.34 g/cm3, a sedimentation coefficient of 156-160S, and is composed of four polypeptides with molecular weights of 30,000-33,000 (VP1), 24,000-27,000 (VP2), 21,000-23,000 (VP3), and 7,000-14,000 (VP4). The genome of hepatitis A virus consists of a single piece of single-stranded RNA which sediments at 32-35S and has a buoyant density of 1.64 g/cm3. The molecular weight of RNA is 2.25 x 10(6) when measured under nondenaturing conditions and 2.8 x 10(6) when measured under fully denaturing conditions. The genome contains a 40-80 nucleotide sequence of polyadenylic and is capable of infecting cell cultures. These findings, together with the observation that the virion is stable at pH 3.0 and resistant to ether and a temperature of 60 degrees for 1 h, indicate that hepatitis A virus should now be classified as an Enterovirus within the family Picornaviridae.

Animals↗
PubMed1982

Serum immunoglobulin levels in acute A, B, and non-A, non-B hepatitis.

Immunoglobulin M, G, and A concentrations were determined by radial immunodiffusion in sera collected from 117 patients with acute hepatitis A, hepatitis B, or non-A, non-B hepatitis. Statistically significant differences in IgG and IgM levels were detected between the three groups. In particular, elevated IgG and almost-normal IgM levels were regularly detected in patients with non-A, non-B hepatitis while the opposite pattern was seen in patients with hepatitis A. Calculation of a serum IgG/IgM ratio enabled discrimination between most patients with non-B hepatitis. In 92% of patients with hepatitis A, the ratio was less than 6, whereas 82% of patients with non-A, non-B hepatitis had ratios of greater than 6. The IgG/IgM ratio may be of value in distinguishing between subjects with the two forms of the disease when specific serologic tests are unavailable.

Hepatitis C↗
PubMed1982

Detection of markers of hepatitis B infection in serum dried on to filter-paper: an application to field studies.

In an attempt to find a cheap, reliable, and convenient method for the transportation and storage of serum specimens during seroepidemiological surveys, a technique in which serum was dried on to pieces of filter paper was developed and evaluated. For the evaluation, a total of 382 sera were selected from the extensive serum collection held by the WHO Collaborating Centre for Virus Reference and Research at Fairfield Hospital, Australia. These sera were dried on to pieces of filter-paper, stored at different temperatures and then tested for the presence of the various markers of infection with hepatitis B virus by solid-phase radioimmunoassay. The results were in complete agreement with those obtained on whole serum specimens. In addition, storage at 4 degrees C, room temperature (22 degrees C), or 37 degrees C for up to 30 days did not alter the sensitivity of the test. This technique may be useful in field surveys, not only for the detection of hepatitis B infection, but also in the study of other diseases and metabolic disorders.

Australia↗
PubMed1981

Restricted replication of human hepatitis A virus in cell culture: intracellular biochemical studies.

When hepatitis A virus was inoculated into Vero cells, virus-specified protein and RNA synthesis was detected. Production of viral protein was detected by electrophoretic analysis in polyacrylamide gels by using a double-label coelectrophoresis and subtraction method which eliminated the contribution of host protein components from the profiles of virus-infected cytoplasm. Eleven virus-specified proteins were detected in the net electrophoretic profiles of hepatitis A virus-infected cells. The molecular weights of these proteins were very similar to those detected in cells infected with poliovirus type 1. Virus-specified protein synthesis could be detected at 3 to 6 h and continued for at least 48 h postinfection, but no significant effect on host-cell macromolecular synthesis was observed. Limited viral RNA replication occurred between 2 and 6 h postinfection. The genomic RNA of hepatitis A virus was extracted and shown to be capable of infecting cells and inducing the same set of proteins as intact virus, indicating that the RNA genome is positive stranded. Progeny virus was never detected in the supernatant fluids of infected cell cultures, and the cells showed no observable cytopathology, even though hepatitis A virus-specific proteins and antigens were being produced. The nature of the defect in the replicative cycle of hepatitis A virus in this system remains unknown.

Animals↗
PubMed1981

Evidence that the genome of hepatitis A virus consists of single-stranded RNA.

Nucleic acid was extracted from purified hepatitis A virus, radiolabeled with 125I, and shown to consist of single-stranded RNA which sediments at 35S and contains sequences of polyadenylic acid. These findings are consistent with hepatitis A virus being a member of the genus Enterovirus within the family Picornaviridae.

Centrifugation, Density Gradient↗
PubMed1980

Detection of hepatitis A virus in the feces of patients with naturally acquired infections.

A prospective study was carried out on 200 patients admitted to Fairfield Hospital, Melbourne, Australia, with acute hepatitis A to determine the frequency with which virus could be detected in their feces. Evidence of infection with hepatitis A virus (HAV) was obtained by detecting IgM specific for HAV in a single serum sample or by demonstrating a rising titer of antibody in paired sera by solid-phase radioimmunoassay. HAV was detected in the feces of 59 of the 200 patients by solid-phase radioimmunoassay and immune electron microscopy. When patients were admitted within one week of the onset of dark urine, 45% were found to be shedding HAV, whereas only 11% of specimens obtained from patients admitted during the second week contained virus. HAV was not detected in fecal specimens collected more than 14 days after the onset of dark urine. These findings suggest that patients admitted to hospital with hepatitis A may still be infectious and that appropriate precautions against fecal contamination should be maintained.

Acute Disease↗
PubMed1980

Detection of specific anti-leptospiral immunoglobulins M and G in human serum by solid-phase enzyme-linked immunosorbent assay.

The enzyme-linked immunosorbent assay (ELISA) was used to detect leptospire-specific immunoglobulin M (IgM) and IgG in the sera of patients infected with leptospiral serovars hardjo, pomona, or copenhageni. All patients produced specific IgM and IgG detectable by ELISA. In contrast, only a few patients produced IgG agglutinins whereas all produced IgM agglutinins. The specificity and sensitivity of the test suggest that the ELISA anti-IgM technique is a suitable method for detecting leptospiral antibodies in human sera for diagnostic and epidemiological purposes.

Agglutination Tests↗
PubMed1980

Coproantibodies in hepatitis A: detection by enzyme-linked immunosorbent assay and immune electron microscopy.

A collection of 104-fecal specimens from 45 patients with hepatitis A, 14 patients with hepatitis B, 10 patients with non-A, non-B hepatitis, 6 patients with diseases other than hepatitis, and 18 healthy adults were studied for the presence of secretory immunoglobulin A and immunoglobulin M to hepatitis A virus by solid-phase enzyme-linked immunosorbent assay and immune electron microsopy. Specific fecal antibody was found only in patients with hepatitis A. Of 54 specimens from patients with hepatitis A, only 10 (18.5%) possessed detectable levels of fecal antibody, and each of these was collected within 10 days from the onset of dark urine. All 10 fecal specimens contained hepatitis A-specific secretory immunoglobulin A, and 4 were also positive for hepatitis A-specific immunoblobulin M. Four of the 10 antibody-positive specimens also contained hepatitis A virus particles which could be shown by immune electron microscopy to be coated with specific secretory immunoglobulin A. Since specific fecal antibody was not detected in all the patients with hepatitis A that were studied, it would appear to have limited diagnostic value, although its detection is evidence of recent infection.

Antibodies, Viral↗
PubMed1980

Iodination of hepatitis A virus reveals a fourth structural polypeptide.

Hepatitis A virus present in the feces of two patients with naturally acquired hepatitis A was purified, radiolabeled with 125I, and analyzed by discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition to the three structural polypeptides previously reported, a fourth polypeptide with a molecular weight of 14,000 was detected and shown to be a component of hepatitis A virus by immune precipitation techniques. Intact virions were also shown to sediment at 160S on sucrose gradients. These findings are consistent with hepatitis A virus being an enterovirus within the family Picornaviridae.

Centrifugation, Density Gradient↗
PubMed1979

Solid-phase enzyme-linked immunosorbent assay for detection of hepatitis A-specific immunoglobulin M.

A solid-phase enzyme linked immunosorbent assay was developed for the detection of immunoglobulin M antibody to hepatitis A virus. The system was capable of detecting hepatitis A-specific immunoglobulin M in a single dilution of serum and appears to be a reliable and rapid means of establishing a diagnosis of hepatitis A infection. Specific immunoglobulin M was only detected in patients with serologically confirmed hepatitis A and not in patients with other forms of hepatitis, chronic liver disease, or autoimmune disease. In patients with hepatitis A, specific immunoglobulin M was usually detectable for 6 weeks after the onset of dark urine, and the longest period for which it was present in any patient was 115 days. This enzyme-linked immunosorbent assay is rapid, simple to perform, and does not require complicated equipment. Provided adequate supplies of purified reagents can be obtained, this enzyme-linked immunosorbent assay procedure is likely to simplify hepatitis A serology, because the same antibody-coated plates can be utilized to detect hepatitis A virus, anti-hepatitis A virus, and hepatitis A-specific immunoglobulin M.

Antibodies, Viral↗
PubMed1979

A solid-phase enzyme-linked immunosorbent assay (ELISA) for detection of antibody to rubella virus.

An enzyme-linked immunosorbent assay was established for detection of antibodies to rubella virus. In this system commercially available rubella antigen was attached to the wells of polystyrene microtitre plates after which sera were added and incubated to allow the formation of antigen-antibody complexes. The presence of bound antibody was detected by adding anti-human globulin coupled to horseradish peroxidase and visually observing the colour change produced after addition of an appropriate substrate. The test was reproducible and simple to perform and had a similar sensitivity to the widely used haemagglutination inhibition system.

Antibodies, Viral↗
PubMed1978

Solid-phase enzyme-linked immunosorbent assay for detection of hepatitis A virus.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of hepatitis A virus in human fecal specimens. Investigations with 88 fecal specimens from 77 patients with suspected viral hepatitis and 8 of their household contacts showed that ELISA was as specific and sensitive as radioimmunoassay and almost as sensitive as immune electron microscopy. The ELISA is quick and simple to perform, does not require sophisticated technical equipment, and can be read with the naked eye, making it suitable for field work and rapid diagnosis.

Antigen-Antibody Reactions↗
PubMed1978

The polypeptides of hepatitis A virus.

Hepatitis A virus was purified from fecal specimens obtained from 3 patients with naturally acquired hepatitis A, by a process of differential centrifugation, chloroform extraction, column chromatography, and isopycnic ultracentrifugation. Analysis of purified virus by discontinuous SDS-PAGE revealed three major polypeptides with molecular weights of 34,000, 25,500, and 23,000 daltons. These polypeptides appear to be specific for hepatitis A virus and have similar molecular weights to three of the four major polypeptides reported for members of the genus Enterovirus within the family Picornaviridae.

Feces↗