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Biomedical subjects

I D Gust

Publications and source records attributed to I D Gust.

At least 55 records · Page 3Linked to original sources
PubMed1989

Nucleotide sequence of high-passage hepatitis A virus strain HM175: comparison with wild-type and cell culture-adapted strains.

The nucleotide sequence of cDNA from a high-passage, cell culture-adapted variant of hepatitis A virus strain HM175 was compared with the previously determined sequences of wild-type virus and two other cell culture-adapted variants. A total of 42 nucleotide changes were detected when the sequence was compared with wild-type virus. Five of these changes were common to all cell culture-adapted strains and a further two changes were shared by the strains that had experienced the greatest number of cell culture passages. The mutations were distributed throughout the genome coding for amino acid substitutions in regions 2B, 2C and 3D with silent changes in 1C and the 5' non-coding region. The possible relevance of these mutations to cell culture adaptation and attenuation is discussed.

Animals↗
PubMed1989

Comparison of core antigen (p24) assay and reverse transcriptase activity for detection of human immunodeficiency virus type 1 replication.

This report compares two assay systems for monitoring human immunodeficiency virus (HIV) replication in peripheral blood leukocyte cultures. A commercial enzyme-linked immunoassay detected core antigen (p24) in 80% of cell cultures from HIV-seropositive individuals, whereas 67% of the cell cultures produced detectable levels of reverse transcriptase activity. There were clearly three patterns of reverse transcriptase activity produced, two of which may evade detection without regular sampling and maintaining cell cultures for more than 4 weeks. Once established, core antigen levels remained high so that cell cultures could be confidently monitored by an intermittent screening regimen.

Cells, Cultured↗
PubMed1988

Recognition of envelope and tat protein synthetic peptide analogs by HIV positive sera or plasma.

A series of synthetic peptides corresponding to segments of HIV encoded proteins were selected using criteria described by Welling et al. [(1985) FEBS Lett. 188, 215]. Synthetic peptide analogs to gp120 (2-13), (55-65), gp41 (582-596) (659-670) and tatIII (71-83) were recognized by 41-67% of sera or plasma from individuals known to be infected with HIV on the basis of virus isolation or Western blot screening. The peptide which reacted with most sera or plasma was gp41 (582-596), a conserved region in the transmembrane glycoprotein. An extended peptide analog, gp41 (579-599), tested against the same samples showed almost 100% reactivity, confirming independent studies identifying a highly immunodominant region of gp41. There was an unexpected high prevalence of antibodies (25%) to the tatIII peptide.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Use of serotype-specific monoclonal antibodies to study the epidemiology of rotavirus infection.

The development of an enzyme immunoassay (EIA) capable of serotyping human rotavirus (HRV) in faecal extracts has enabled us to retrospectively study the epidemiology of rotavirus infection in Melbourne. Of 552 stored specimens obtained from individuals with rotavirus-associated gastroenteritis between 1975 and 1986, the serotype could be determined in 62%. Infection was most prevalent in two groups, neonates and children aged between 12 and 24 months. In these groups infection was due to different serotypes, type 1 in older children and an untypable virus in infants. Serotype 1 strains were detected in greater numbers than the other serotypes and circulated in each year of the study. Serotype 2 rotaviruses were associated with a large epidemic in 1978, but have been detected only rarely since.

Age Factors↗
PubMed1988

Evaluation of enzyme-linked immunosorbent assays: a method of data analysis.

Diagnostic tests are usually evaluated in terms of simple qualitative measures of sensitivity and specificity. When comparing different quantitative assays such as ELISAs, it is often more useful to deal with actual values (sample optical density/cut-off optical density ratio (OD ratio] rather than the qualitative relationship to the cut-off, i.e. positive or negative. This allows for a statistical approach to the questions of sensitivity and specificity. The National HIV Reference Laboratory of Australia has developed an approach for determining statistical estimates of sensitivity and specificity in terms of delta (delta). Delta is defined as the distance of the mean OD ratio of the sample population from the cut-off measured in standard deviation units. This paper discusses the derivation of this measurement and its usefulness when evaluating ELISA tests.

Data Interpretation, Statistical↗
PubMed1988

An evaluation of competitive and second generation ELISA screening tests for antibody to HIV.

Two competitive anti-HIV ELISA screening assays (Behring and Wellcozyme) and two second generation assays using antigens generated by recombinant DNA technology (Abbott) and synthetic peptides (Biochrom) were evaluated against common panels of anti-HIV positive sera and sera known or thought likely to give false positive reactions. The assays were also tested on fresh sequential blood donations. Conventional estimates of sensitivity and specificity did not reveal a significant difference between the assays. Statistical analyses using log10 transformed data to determine delta values (the distance of the mean optical density (OD) ratio from the cut-off measured in standard deviation units) showed the Abbott assays to have the highest probability (greater than 99.99%) of detecting anti-HIV positive samples and the Behring assay as having the highest probability (greater than 99.99%) of correctly identifying anti-HIV negative specimens. The combined data from conventional estimates of sensitivity and specificity and delta values suggests that the Abbott assay is the test of choice for screening purposes.

Data Interpretation, Statistical↗
PubMed1988

A preliminary evaluation of five HIV antigen detection assays.

Five commercial assays for detecting HIV antigen were evaluated using a panel of 40 coded samples in six laboratories. All assays were capable of detecting HIV-1 antigen (HIV-1 Ag), and are likely to prove useful for monitoring supernatant fluids from a variety of cell cultures. The concentration of HIV-1 protein which the assays detected varied from 25 ng/ml down to 25 pg/ml. Three of the five assays were also able to detect HIV-2 Ag. More extensive evaluations are needed to determine the sensitivity and specificity of these assays on serum samples and body fluids.

Antibodies, Viral↗
PubMed1987

Cellular changes associated with persistent hepatitis A infection in vitro.

The rate of division, morphology and ultrastructure of BSC-1 cells, persistently infected with hepatitis A virus (HAV), were compared with uninfected cells for 60 days after splitting of the cells. Both control and infected cells showed a biphasic growth pattern marked firstly by increasing cell density and high mitotic rate (exponential phase) and then high constant cell density and little mitosis (stationary phase). Immunoperoxidase studies showed that hepatitis A antigen (HAAg) appeared as cytoplasmic granules approximately one third of the way through the exponential phase in infected cells. The percentage of cells with HAAg rose until the early stationary phase when virtually all cells contained antigen. Radioimmunoassay demonstrated an increase in HAAg per cell in the stationary phase. Radioimmunofocus assay and immune electron microscopy confirmed the presence of HAV in infected cells in the stationary phase. Thin sectioning electron microscopy showed cytoplasmic annulate lamellae in infected cells of both phases but not in control cells.

Animals↗
PubMed1987

Comparison of enzyme immunoassay and reverse transcriptase assay for detection of HIV in culture supernates.

An enzyme immunoassay (EIA) was developed for detection of human immunodeficiency virus antigen (HIV Ag) in tissue culture supernatants. The assay was found to be specific for HIV and cheaper, easier to perform and more sensitive than the generally used reverse transcriptase (RT) assay. Cultures of peripheral blood leucocytes (PBL) from 106 patients with acquired immune deficiency syndrome (AIDS), AIDS related complex (ARC), healthy anti-HIV positive subjects and healthy anti-HIV negative subjects were held for 35 days and the supernatant fluid tested at regular intervals by EIA and RT. Of these 106 cultures, the presence of HIV was detected by EIA in 27 and by RT in 21. While six cultures were positive by EIA alone, none were positive by RT alone; the specificity of the results in the six EIA positive RT negative cultures was confirmed by subculture. In the 21 cultures in which HIV was detected by both techniques, the EIA became positive first on 10 occasions; in the remaining cultures both tests became positive at the same time. The HIV Ag assay reduces the time taken to process specimens and thus increases the efficiency and reduces the cost of isolation procedures.

Antigens, Viral↗
PubMed1987

Hepatitis A.

Explore the source record for details and available documents.

Age Factors↗
PubMed1987

Australian hemophiliac recipients of voluntary donor blood products longitudinally evaluated for AIDS. A clinical and laboratory study, 1983-1986.

One hundred and sixty-one Australian patients with hereditary bleeding disorders comprising hemophilia A (120), hemophilia B (18), von Willebrand's disease (16), and seven symptomatic female hemophilia A or B carriers were screened for clinical and serological evidence of exposure to HTLV-III/LAV/ARV/HIV infection. During the previous five years (1979-1984) they had been treated almost exclusively with blood products derived from Australian voluntary donors. The prevalence of HTLV-III antibodies in 1985 was 45%, with the highest frequency being in those with severe hemophilia A (78%) and the lowest in patients with hemophilia B (6%). Antibody positivity correlated with a reduced absolute T helper (T4) cell numbers and/or an inverted T4:T8 ratio. Lymphadenopathy was detected in 23 subjects but only 13 had an abnormal T cell ratio. Comparison of seropositivity and T4:T8 ratios in 32 patients studied in 1983 and again in 1985 suggested that T4 cell deficiency reflected HTLV-III exposure rather than being a predisposing factor for infection with the virus. Individual patients showed considerable fluctuation in T cell subsets over a 12 month period of follow-up, but as a population there was a slight trend with time towards diminishing T4:T8 ratio only in the antibody positive hemophilia A patients of mild to moderate severity. Three (2%) of the 161 patients screened to date have developed confirmed AIDS with fatal outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1987

Isolation of HIV from Australian patients with AIDS, AIDS related conditions and healthy antibody positive individuals.

The Fairfield Hospital experience with isolation of HIV from peripheral blood leucocytes, cerebrospinal fluid and semen is described. To date HIV has been isolated from single specimens of blood from 45% of patients with AIDS, 35% of patients with lymphadenopathy syndrome AIDS-related complex or ARC and 14% of asymptomatic antibody positive individuals. HIV was recovered from peripheral blood leucocytes in the presence of phytohemagglutinin and interleukin-2. The presence of virus in the supernatant fluid was detected using reverse transcriptase and immunofluorescence assays. Supernatants with borderline activity were confirmed by infection of a continuous cell line.

AIDS-Related Complex↗
PubMed1987

Virus and virus-like particles in the faeces of cats with and without diarrhoea.

Negative staining electron microscopy was used to identify viruses in 166 normal and 62 diarrhoeal faecal samples from 208 cats admitted to an animal shelter during a 16-month period (March 1984 to June 1985). On the basis of size and shape 7 distinct viral types were detected: 24 nm parvovirus-like particles, 30 nm astrovirus, 30 nm picornavirus-like particles, reovirus, rotavirus, coronavirus and a 75 nm "togavirus-like" particle. The incidence of these particles in the 208 cats was 11%, 7%, 6%, 0.4%, 5%, 1% and 1% respectively. Virus isolation studies using 40 of the faecal samples succeeded in isolating reovirus 1 in 2 cases. Immune electron microscope studies demonstrated the presence of antibody in a human serum to cat astrovirus, but failed to clarify the identity of the parvovirus-like particles and picornavirus-like particles, other than showing that some of the parvovirus-like particles were not related to feline panleukopenia virus. It was found that parvovirus-like particles, astrovirus, picornavirus-like particles, reovirus and rotavirus could be excreted by cats with normal faeces as well as cats with diarrhoeal faeces. Parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus could be excreted in high concentration in normal faeces. There was no simple relationship between age and diarrhoea in the population of cats studied. Age was not a critical factor in the excretion of parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus. The incidence of diarrhoea was not clearly associated with the seasons.

Age Factors↗
PubMed1986

Study of the immunogenicity and infectivity of hepatitis B-containing stabilized plasma-protein solution.

In early 1984, five patients who were undergoing plasmapheresis at a Melbourne hospital developed a transient hepatitis B surface antigenaemia. A common batch of stabilized plasma-protein solution (SPPS) that was included in the replacement therapy for each patient was found to contain hepatitis B surface antigen (HBsAg). A follow-up study was undertaken of these patients and others who were known to have received SPPS from the same batch (in total, 10 patients were followed for a median of 46.5 weeks). No patient developed evidence of hepatitis, although one patient developed antibody to surface antigen. It was concluded that the manufacturing process was effective in destroying the infectivity of the HBsAg-positive plasma that was used in this batch of SPPS and that the final product was poorly immunogenic in these patients.

Adolescent↗