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Biomedical subjects

C J Burrell

Publications and source records attributed to C J Burrell.

At least 19 recordsLinked to original sources
PubMed1992

High prevalence of human papillomavirus transcripts in all grades of cervical intraepithelial glandular neoplasia.

Cervical biopsy specimens containing cervical intraepithelial glandular neoplasia (CIGN) were examined for the presence of human papillomavirus (HPV) RNA transcripts by in situ hybridization with iodine 125-labeled riboprobes. HPV RNA was detectable in 95.2% of biopsy specimens. HPV 16 RNA was present in 12, HPV 18 in 27, and both in 1 of the 42 cases examined. Among HPV-positive cases, HPV RNA was detectable in all grades of CIGN and, in three cases, in glands displaying only minimal nuclear abnormality insufficient for a diagnosis of CIGN. Patients with HPV RNA-positive CIGN were younger than those with negative findings for HPV, and patients with less severe grades of CIGN showed a trend toward a younger age of presentation than patients with severe glandular lesions. Increasing grades of CIGN may reflect progressive stages in the development of cervical adenocarcinoma, and this progression may closely involve HPV gene expression from its earliest stages.

Adult↗
PubMed1992

Hepatitis B virus markers in children and staff in Northern Territory schools.

OBJECTIVE: To measure the prevalence of hepatitis B virus (HBV) infection in children and staff at Northern Territory schools. DESIGN: Children in Years 5-7 in 24 selected primary schools were invited, with parental consent, to provide demographic and ethnic details, and a capillary blood sample for tests for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs). School staff participated on a similar basis. PARTICIPANTS: 1104 children, comprising 556 from ethnic groups (originating from the United Kingdom, Ireland and northern Europe) previously reported as "low HBV prevalence", 439 Aboriginal Australians, and 109 from "other" ethnic groups (originating from Asia, the Pacific, the Middle East and southern Europe); and 209 school staff, comprising 180 from "low HBV prevalence" ethnic groups, and 29 from Aboriginal and other ethnic groups. RESULTS: Prior HBV infection (i.e. serum positive for HBsAg or anti-HBs) was detected in 28.7% of children (46.9% of 439 Aborigines; 13.7% of the 556 children from the "low prevalence" groups and 32.1% of the 109 from the "other" groups). HBsAg was detected in 8.2% of Aboriginal children, in 0.36% of those from "low prevalence" groups, and in 1.8% of those from the "other" groups. Aboriginal children in rural schools had the highest prevalence of HBV: 5.4% were positive for both HBsAg and anti-HBs, and an additional 9.8% were positive for HBsAg alone. In urban schools, the prevalence was highest in the "other" ethnic groups. For school staff, the prevalence of HBV infection was 12.8% for those from "low prevalence" ethnic groups, and 37.9% for those from all remaining groups (including Aborigines). CONCLUSION: In the Northern Territory the prevalence of past HBV infection is high in children and school staff from ethnic groups previously known to be at higher risk of HBV infection. For students and staff from ethnic backgrounds expected to be at low risk, HBV prevalence is greater than in individuals from similar backgrounds in other parts of Australia. HBV vaccination is now offered to all infants in the Northern Territory. These results also provide a rationale for the more widespread use of HBV vaccine in other situations where significant HBV transmission might occur.

Child↗
PubMed1992

Intracellular factors, but not virus receptor levels, influence the age-related outcome of DHBV infection of ducks.

Previous serological studies of experimental infection with duck hepatitis B virus (DHBV) have shown that the outcome of infection depends largely on the age of the duck at the time of inoculation. To examine the hypothesis that decreased susceptibility with increased age might be due to the loss of the virus receptor on hepatocyte membranes in adult ducks, we performed receptor binding studies using intact serum-derived DHBV virions and purified liver plasma membranes from both young ducklings and adult ducks. These studies showed that (1) DHBV was able to bind specifically to duck liver plasma membranes but not to internal membranes; (2) this binding could be inhibited by a monoclonal antibody to DHBV preS, a corresponding region in hepatitis B virus that binds to human hepatocytes; and (3) there was no significant difference in the receptor binding ability between plasma membranes from ducklings and from adult ducks. Since hepatocytes in the neonatal ducks are actively dividing, in contrast to the situation in adult ducks, we examined the effect of partial hepatectomy on DHBV-carrier ducks. A sharp increase was noted in the level of DHBV in the serum after partial hepatectomy suggesting that DHBV replication was enhanced in dividing hepatocytes. Thus the age-related difference in susceptibility of ducks to DHBV infection is not due to loss of the receptor but may be related to an intracellular event associated with cell division.

Aging↗
PubMed1992

Synthesis of human immunodeficiency virus DNA in a cell-to-cell transmission model.

Cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1) was modelled by coculturing virus-infected cells with uninfected target cells at a ratio of 1:4. While H9 cells persistently infected with HTLV-IIIB did not contain unintegrated viral DNA detectable by Southern blotting, when cocultured with uninfected HUT-78 cells the mixed culture effectively underwent a new round one-step virus replication which began de novo synthesis of free viral DNA within 4 hours. Linear DNA was synthesized before the accumulation of circular DNA, and two seemingly distinct phases of viral DNA synthesis were involved. When both virus donor cells and recipient cells were arrested in the G0/G1 phase of the cell cycle, accumulation of circular viral DNA was inhibited. In contrast to cell-free virus infection of resting human peripheral blood mononuclear cells (PBMC), where no free viral DNA of discrete sizes could be detected by Southern blot, cell-to-cell transmission infection of resting PBMC resulted in the synthesis of full-length linear as well as circular viral DNA. The efficiency with which cell-to-cell transmission of HIV initiates virus replication underlines the importance of this mode of transmission in virus dissemination in vivo.

Cell Cycle↗
PubMed1992

Differing prevalence of human papillomavirus RNA in penile dysplasias and carcinomas may reflect differing etiologies.

Penile intraepithelial neoplasias grade 3 (PIN 3) and penile carcinomas were examined for the presence of human papillomavirus (HPV) RNA transcripts by in situ hybridization using 125I-labeled RNA probes. Human papillomavirus transcripts were detected in all 10 PIN 3 lesions not associated with invasive malignant conditions but were present in only 29% of penile carcinomas (9 of 26 squamous cell carcinomas and none of 5 verrucous carcinomas). Human papillomavirus RNA-positive penile cancers were significantly more likely to exhibit adjacent PIN 3 lesions than were HPV-negative tumors, and PIN 3 lesions adjacent to tumors always contained the same HPV-RNA type as was present in the invasive tumor. The development of most penile cancers may be unrelated to HPV infection. Future epidemiologic studies of the role of sexually transmitted factors in the development of penile carcinoma should distinguish between HPV-positive and HPV-negative penile cancers.

Adult↗
PubMed1992

De novo reverse transcription is a crucial event in cell-to-cell transmission of human immunodeficiency virus.

The proposal that replication of human immunodeficiency virus type 1 (HIV-1), mediated by cell-to-cell transmission of the virus, might bypass de novo reverse transcription was tested by using one-step cell-to-cell and cell-free virus infection systems. Two well characterized reverse transcriptase (RT) inhibitors, azidothymidine at 20 microM and phosphonoformic acid at 100 micrograms/ml, blocked HIV replication completely following both cell-free virus and cell-to-cell transmission infection, as determined from the kinetics of unintegrated viral DNA synthesis and supernatant RT production after virus infection. Our results confirm that de novo reverse transcription is a crucial and mandatory event in HIV-1 replication following cell-to-cell transmission of the virus.

Antiviral Agents↗
PubMed1992

Transcription patterns of human papillomavirus type 16 in genital intraepithelial neoplasia: evidence for promoter usage within the E7 open reading frame during epithelial differentiation.

Human papillomavirus (HPV) type 16 transcription was analysed by in situ hybridization using 125I-labelled subgenomic riboprobes, from 26 genital intraepithelial neoplastic (IN) lesions, in formalin-fixed biopsies from 18 different cases. Distinct transcription patterns separable by the presence or absence of late gene transcription were detected. In 12 lesions, late gene expression was absent; HPV transcripts corresponding to the E6 and E7 open reading frame (ORF) were detectable in all basal cells and were usually evenly distributed through all layers of the epithelium. Transcripts corresponding to the E1, E2 and E2/E4 ORFs were present in nine of 12 lesions and displayed a similar distribution. In 14 lesions late gene transcripts were present. E6 and E7 transcripts were detectable basally in all but one lesion. The levels of E7 but not E6 transcripts were markedly increased in the superficial cells of differentiating epithelia, with an identical distribution and at similar levels to those of the E2/E4 transcript. We propose that the most abundant transcript in genital IN lesions containing late gene expression is an E7/E1 [symbol: see text] E2/E4 transcript corresponding to that reported in HPV-6/11 condylomata and which is derived from a similar promoter within the E7 ORF.

Cell Transformation, Neoplastic↗
PubMed1992

Cor triatriatum sinister, not mitral stenosis, in an adult with previous Sydenham's chorea: diagnosis and preoperative assessment by cross sectional echocardiography.

In cor triatriatum sinister, one of the rarest congenital cardiac anomalies, a membrane divides the left atrium into a pulmonary venous component above and the vestibule below. The importance of the anomaly lies in the effects of the resultant pulmonary venous obstruction that usually present in the first year of life and can mimic obstructed total anomalous venous drainage or congenital mitral stenosis. A case presented as mitral stenosis in the third decade of life, ten years after a well documented episode of Sydenham's chorea. The diagnosis was made rapidly by transthoracic echocardiography and transoesophageal echocardiography was used for complete assessment. Cardiac catheterisation added nothing to the non-invasive diagnosis or the preoperative assessment. Uncomplicated corrective surgery was undertaken.

Adult↗
PubMed1991

Increased age and mortality associated with cervical carcinomas negative for human papillomavirus RNA.

Attempts to relate presence and type of human papillomavirus in cervical carcinoma with prognosis have yielded conflicting results. To further investigate this relation, the association between survival of cervical cancer patients after diagnosis and the presence of human papillomavirus (HPV) RNA within the tumour was assessed retrospectively. Formalin-fixed biopsy specimens from 212 patients with cervical carcinoma who had been followed for up to 6 years were tested by in-situ hybridisation with 125I-labelled riboprobes. HPV-RNA-positive women were 11.9 years younger than HPV-negative women at diagnosis (p less than 0.001). Case-fatality rates from cervical cancer rose with absence of HPV RNA, age at diagnosis, or FIGO stage. Multivariate analysis confirmed that absence of detectable HPV RNA and advanced FIGO stage were independent risk factors. No differences in survival between HPV types 16, 18, 31, or 33 were seen. These observations suggest that cervical carcinoma patients fall into two groups--a younger, HPV-RNA-positive group, with a better prognosis, and an older, HPV-RNA-negative group with poorer prognosis. Treatment regimens for the two groups may need to differ.

Adenocarcinoma↗
PubMed1991

Differing characteristics of human papillomavirus RNA-positive and RNA-negative anal carcinomas.

Anal carcinomas were tested for the presence of human papillomavirus (HPV) RNA transcripts by in situ hybridization using 125I-labeled RNA probes. The HPV transcripts were detected in 73.2% of 41 nonglandular anal carcinomas but in none of six anal or 11 rectal adenocarcinomas. In anal nonglandular carcinomas, no difference in the percentage of tumors that were HPV RNA positive was observed between tumors classed as basaloid carcinomas or squamous cell carcinomas. Patients with HPV RNA-negative tumors were significantly older (9.2 years) than those with HPV RNA-positive tumors. Anal intraepithelial neoplasia Grade 3 in the surrounding epithelium was seen in 14 of 25 assessable HPV RNA-positive tumors and in none of nine assessable HPV RNA-negative tumors. Anal tumors may include two separate clinical and biologic groups distinguished by their dependence, or lack of dependence, on HPV RNA expression for maintenance of the neoplastic state.

Adenocarcinoma↗
PubMed1991

Evaluation of accuracy of the wash impression technique to rebase and replace the resilient part of a soft-lined denture.

The dimensional inaccuracies that might be introduced during a wash impression technique within a heat-cured acrylic resin tray lined with a silicone resilient denture base material were investigated with the use of an electronic digitizer. Casts were poured from impressions of a machined metal die using a light- and heavy-bodied addition silicone in the soft-lined tray and compared with casts poured from impressions made in a hard-based tray and with the master die itself. The dimensions of the casts poured from the heavy-bodied impression in the soft-lined trays were significantly different from those poured from impressions in the hard-based tray when compared with the metal die. Those produced from the light-bodied material showed no statistically significant dimensional difference.

Acrylic Resins↗
PubMed1991

Hepatitis delta antigen is necessary for access of hepatitis delta virus RNA to the cell transcriptional machinery but is not part of the transcriptional complex.

To examine the role of hepatitis delta virus antigen in the replication of hepatitis delta virus RNA, we have transfected a stable HDAg-positive cell line (A3) and the parental HDAg-negative line (HepG2) with HDV RNA produced in vitro; synthesis of complementary HDV RNA was only detected in HDAg-positive cultures. In contrast, nuclear homogenates from both HDAg-positive and -negative cells synthesized comparable levels of complementary RNA from exogenous HDV RNA. These findings indicate that HDAg is not a necessary component of the transcriptional complex and suggest with other evidence, that a major role for HDAg is likely to be transport of HDV RNA from cytoplasm to nucleus. Transcription of HDV RNA by intact nuclei was sensitive to 1 microgram/ml alpha-amanatin providing firm evidence that, like viroids, this function is performed by host RNA polymerase II.

Amanitins↗
PubMed1991

A survey of nosocomial respiratory viral infections in a children's hospital: occult respiratory infection in patients admitted during an epidemic season.

OBJECTIVE: To define the extent of shedding of respiratory viruses and Mycoplasma pneumoniae among a population of pediatric patients admitted to the hospital during a winter epidemic period and to identify nosocomial infections within this population. DESIGN: An open, prospective survey of patients admitted to three wards (General Medical, Respiratory Infectious, and Infectious Diseases) of a pediatric hospital during a defined three-month period. PATIENTS: All patients with medical, respiratory, and infectious conditions admitted to three wards of the Adelaide Children's Hospital had nasopharyngeal aspirations performed at the time of admission with the purpose of documenting viral and M pneumoniae shedding. Patients were monitored daily for the development of symptoms of respiratory infection or new symptoms of respiratory disease. Such patients underwent a further nasopharyngeal aspiration for the purpose of diagnosing hospital-acquired infection. RESULTS: Nasopharyngeal aspirations were obtained from 601 patients. Forty-seven percent of asymptomatic patients were positive for a respiratory virus or M pneumoniae, and 61% of patients with respiratory symptoms were also positive. Gastroenteritis patients shed viruses in 66% of cases. Respiratory symptoms were initially overlooked by admitting physicians but subsequently identified in 110 cases, and 46% of these were found to be positive for a respiratory virus or M pneumoniae. There were 18 possible hospital acquired infections among the 293 initially virus-negative patients. Multiple isolates were obtained from a substantial number of patients, especially those with respiratory symptoms. CONCLUSIONS: A substantial proportion of all patients admitted to a pediatric hospital during winter represent a potential source of infection, and strict infection control measures should be enacted to limit the spread of these infections.

Australia↗
PubMed1991

A community outbreak of epidemic keratoconjunctivitis in central Australia due to adenovirus type 8.

A large outbreak of epidemic keratoconjunctivitis occurred in Alice Springs, Australia, between July and September 1989. Initially, there was a large outbreak within two child care centers, followed by a more prolonged outbreak within the community. A simultaneous outbreak occurred among staff at the local hospital. Infected children developed mild conjunctivitis, whereas adults developed typical keratoconjunctivitis. Conjunctival swabs from 30 cases were cultured and adenovirus was recovered from 18, all of which were typed by neutralization assay as adenovirus type 8. DNA restriction fragment analysis of the genomes of 5 isolates revealed they were identical, distinct from prototype adenovirus type 8, and nearly identical to adenovirus genome type 8C (Ad-8C), which was previously reported in the southern United States in the early 1970s. Ad-8C was present in another region of Australia greater than or equal to 1 year before the epidemic.

Adenovirus Infections, Human↗
PubMed1991

Presence and distribution of human papillomavirus sense and antisense RNA transcripts in genital cancers.

RNA transcription in eight human papillomavirus (HPV) type 16-positive genital carcinomas and in two cervical squamous cell carcinoma (SCC)-derived cell lines was analysed by in situ hybridization using 125I-labelled subgenomic riboprobes. Transcripts corresponding to the E6 and E7 open reading frames were always present, except within the keratinizing layers of differentiated SCCs. Intranuclear E1 gene transcripts were detectable in both cell lines and some tumours whereas E2/E4 transcripts were absent from five of seven assessable tumours, suggesting transcription from integrated viral DNA. When mRNA sense riboprobes were used as controls, no signal was seen in the two cell lines; however, three tumours contained a focal, intense nuclear RNase-sensitive signal using mRNA sense riboprobes. This antisense RNA signal mapped across the whole genome including the noncoding region. In one tumour, the presence of antisense RNA was independently confirmed by using E7 and E2/E4 RNA probes of both orientations in RNase protection assays. Transcription of antisense RNA may be a natural feature of some HPV-positive genital tumours and its possible role in modulating cell behaviour in vivo requires further investigation.

Carcinoma, Squamous Cell↗
PubMed1991

Direct evidence for cytotoxicity associated with expression of hepatitis delta virus antigen.

It has been postulated that hepatocyte injury resulting from infection with hepatitis D virus may be caused by a direct virus cytotoxicity in contrast to immune-mediated injury associated with hepatitis B virus. We have transfected HeLa and HepG2 continuous cell lines with a recombinant plasmid containing the hepatitis D antigen gene under the inducible control of the human metallothionein promoter. The addition of zinc to the cell culture medium then led to the expression of hepatitis D antigen associated with, in the short term, a significant reduction in the rate of RNA but not DNA synthesis and, in the longer term, cell death. The necrotic cells had pyknotic nuclei and shrunken eosinophilic cytoplasm; these necrotic cells resembled the apoptotic bodies seen in hepatitis D virus-related hepatitis. The level of hepatitis D antigen in individual cells that produced these changes was similar to the level of hepatitis D antigen in hepatocytes from a chimpanzee with acute hepatitis D virus infection. We conclude that the expression of hepatitis D antigen resulted in significant cytotoxic changes in these cells, providing strong support for the view that hepatitis D antigen may be specifically cytotoxic to infected hepatocytes in vivo.

Animals↗
PubMed1991

Cell culture model systems to study HDV expression, replication and pathogenesis.

Due to the transient nature of HDV replication in natural and experimental hosts and to the inability of the virus to replicate in easily handled cell lines, studies of the replication and expression of HDV have been impeded. These difficulties have been overcome by the development of the cell lines described in this paper.

Animals↗