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Biomedical subjects

W D Rawlinson

Publications and source records attributed to W D Rawlinson.

At least 19 recordsLinked to original sources
PubMed2001

Antiviral agents for influenza, hepatitis C and herpesvirus, enterovirus and rhinovirus infections.

Advances in antiviral therapy have involved both development of new, effective drugs and modification of pre-existing drugs or regimens to increase effectiveness. New agents against influenza virus are the neuraminidase inhibitors zanamivir and oseltamivir, which target specific viral processes and have minimal side effects. New agents for herpesviruses (famciclovir, valaciclovir, valganciclovir) have greater oral bioavailability, allowing less frequent dosing, but mechanisms of action are similar to older agents (aciclovir, ganciclovir). Pleconaril has some activity against enteroviruses and is available for compassionate use in meningitis; it also shows some efficacy against rhinoviruses in ongoing trials, but is not available for routine clinical use. Hepatitis C treatment efficacy has improved dramatically with the introduction of combination interferon-ribavirin therapy, with sustained-response rates up to 60%.

Antiviral Agents↗
PubMed2001

Hepatitis and death following vaccination with 17D-204 yellow fever vaccine.

We describe a man vaccinated with the 17D204 strain of yellow fever virus, who subsequently died of yellow fever. Sequencing of the NS5-39 untranslated region showed that the virus isolated from the patient was identical to the vaccine strain of the same batch, and different from wild-type virus. Both viruses contained a mutation, although the association of this mutation with virulence is unknown. Severe, rapidly progressive, and ultimately fatal disease can follow use of the 17D204 vaccine strain. There is need for renewed discussion as to the safety of the vaccine and the indications for its use.

Adverse Drug Reaction Reporting Systems↗
PubMed2001

Congenital and perinatal infections with cytomegalovirus.

Congenital cytomegalovirus (CMV) infections remain the leading viral cause of congenital malformations in the developed world. Despite advances in our knowledge, the epidemiology and natural history of congenital CMV infection are still poorly understood, particularly in Australia. Congenital CMV causes illness ranging from no clinical disease (asymptomatic, but infected) through to prematurity, encephalitis, deafness and haematological disorders and death. Perinatal CMV acquisition usually results in less severe illness including asymptomatic infection, acute infection with hepatitis, fever, and pneumonitis. CMV infects only humans, and in vitro and in vivo models for intrauterine infection are required in order to test new treatments, and better describe the pathogenesis of congenital CMV. Using new knowledge of the epidemiology and natural history of CMV, treatment regimens during late pregnancy are currently undergoing clinical trial although no definitive recommendations are available.

Amniocentesis↗
PubMed2001

Integrons and gene cassettes in the enterobacteriaceae.

Integrons were detected in 59 of 120 (49%) urinary isolates of Enterobacteriaceae by PCR using degenerate primers targeted to conserved regions of class 1, 2, and 3 integrase genes. PCR sequencing analysis of the cassette arrays revealed a predominance of cassettes that confer resistance to the aminoglycosides and trimethoprim.

Aminoglycosides↗
PubMed2001

Diagnosis of enteric pathogens in children with gastroenteritis.

The aim of this study was to determine the isolation trends of common and emerging pathogens in children over a 12-month period. The study group included 412 children under 6 years with diarrhoea who were either hospitalised, or seen in the outpatients department of The Sydney Children's Hospital. Pathogens were detected in 137 (33%) samples, with rotavirus most common (40%), followed by adenovirus (26%), astrovirus (12%), Campylobacter jejuni (12%), Salmonella spp. (10%) and Giardia lamblia (< 1 %). Giardia-specific antigen (GSA) was detected in 11 of 382 (3%) using an enzyme immunoassay (EIA), and this included four samples in which cysts of G. lamblia were detected by microscopy. Using electron microscopy (EM), viruses were detected in 29 of 120 (24%) samples from hospitalised children and 53 of 171 (31%) outpatients (P = 0.23). Amongst this subset, Norwalk-like viruses (NLVs) were detected by RT-PCR in 10 samples including six of 14 with small round viruses, one of seven with small viral-like particles (SVLPs), and three of 126 EM-negative samples. Lactoferrin, detected by EIA, was 59% more likely to be positive in samples infected with salmonella/campylobacter than in samples in which bacterial pathogens were not isolated. As an indicator for infection with these bacterial agents, the assay showed a sensitivity and specificity of 95 and 40.3%, respectively. A routine microbiological analysis of stools from children of this age group should include a screen for foodborne bacterial agents and rotavirus. Tests for adenovirus, astrovirus and NLVs should be secondary. The cost-effectiveness of including the EIAs for lactoferrin and G. lamblia in the routine testing protocol needs to be evaluated.

Animals↗
PubMed2001

Influenza outbreak in a correctional facility.

The outbreak of influenza in a corrections facility occurred during August 2000. The outbreak progressed following introduction of the disease by a member of the public to the facility. Rapid diagnosis and typing of the influenza isolates was available, although two prisoners required hospital admission due to the severity of complications at the time of diagnosis. The group demonstrated rapid transmission of the virus by the respiratory route and probably by fomites. The identified infecting virus was A/Moscow-like, an H3N2 subtype typically associated with large outbreaks. Prevention of such outbreaks will involve either achieving high rates of vaccination within the risk groups, or rapid (possibly point of care) diagnosis with the institution of antiviral therapy within 48 hours of symptoms. Influenza control within institutions is feasible using such strategies, although it requires considerable planning to have such approaches in place during winter--a time when institutional staff absenteeism is typically high.

Disease Outbreaks↗
PubMed2000

From Bittner to Barr: a viral, diet and hormone breast cancer aetiology hypothesis.

It is hypothesized that the human homologue of the mouse mammary tumour virus (HHMMTV) and other viruses, such as human papillomavirus (HPV) and Epstein-Barr virus (EBV), act as cofactors with diet, oestrogens and other hormones in the initiation and promotion of some types of breast cancer in genetically susceptible women. It is further hypothesized that diet influences the risk of breast cancer, through its influence on oestrogen metabolism and that of other hormones, in combination with genetic and infectious agents.

Breast Neoplasms↗
PubMed2000

Mapping dispersed repetitive loci using semi-specific PCR cloning and somatic cell hybrid mapping.

A simple and effective method based upon semi-specific PCR followed by cloning has been developed. Chromosomal mapping of the generated fragment on a somatic cell hybrid panel identifies the chromosomal position, and yields a unique sequence tag for the site. Using this method, the chromosomal location of one porcine endogenous retrovirus (PERV) was determined. The porcine genomic sequences were first amplified by PCR using a PERV-specific primer and a porcine short interspersed nuclear element (SINE)-specific primer. PCR products were cloned, and those sequences that contained PERV plus flanking regions were selected using a second round of PCR and cloning. Sequences flanking the PERV were determined and a PERV-B was physically mapped on porcine chromosome 17 using a somatic hybrid panel. The general utility of the method was subsequently demonstrated by locating PERVs in the genome of PERV infected human 293 cells. This method obviates the need for individual library construction or linker/adaptor ligation, and can be used to quickly locate individual sites of moderately repeated, dispersed DNA sequences in any genome.

Animals↗
PubMed2000

Transmission of porcine endogenous retroviruses in severe combined immunodeficient mice xenotransplanted with fetal porcine pancreatic cells.

BACKGROUND: Xenotransplantation using pig organs or tissues may alleviate the human donor organ shortage. However, one concern is the potential transmission of pig pathogens to humans, especially pig endogenous retroviruses (PERV), which infect human cell lines in vitro. In this report, the cross-species in vivo transmission of PERV by xenotransplantation was studied using a severe combined immunodeficient (SCID) mouse model. METHODS: Twenty-one SCID mice were transplanted with fetal pig pancreatic cells and left for periods from three to 41 weeks before being killed. DNA and RNA were extracted from liver, spleen, and brain of these mice, and examined for PERV using nested polymerase chain reaction (PCR) and reverse transcriptase-PCR. The pig mitochondrial cytochrome oxidase II subunit gene (COII) was also amplified to monitor the presence of pig cell microchimerism in xenotransplanted tissues, and a housekeeping gene was included to monitor the DNA quality and quantity. RESULTS: Examination of 39 DNA samples from tissues of the 21 xenografted mice identified two mouse tissues (M4-liver and M19-spleen) that were positive for PERV but negative for COII. A total of 23 (59%) of the mouse tissues were positive for both PERV and COII, 6 (16%) were negative for both, and 8 (20%) were positive for COII only. PCR and direct sequencing of the PCR products identified three PERV variants, which were different from the PERV sequence detected by PCR direct sequencing from the pig donor cells. CONCLUSIONS: The PERV+/COII- results from M4-liver and M19-spleen indicated the presence of PERV transmission from pig to mouse tissue. The PERV variants detected in the mouse tissues indicated that different PERVs were transmissible from the pig to mouse tissue during xenotransplantation. The negative reverse transcriptase-PCR results for PERV from three mouse samples including M4-liver and M19-spleen suggest there was no active PERV transcription in the mouse tissues, although this would need to be studied further.

Animals↗
PubMed2000

Hepatitis C prevalence among Australian injecting drug users in the 1970s and profiles of virus genotypes in the 1970s and 1990s.

OBJECTIVES: To examine the seroprevalence of hepatitis C virus (HCV) in the Australian injecting drug-using community in the 1970s, and to compare the profile of HCV genotypes with that seen in the 1990s. DESIGN: Investigation of stored sera that were collected from injecting drug users in the 1970s and comparison with sera collected in the 1990s. SETTING: Inner Sydney, 1974-1975 and 1994-1996. PATIENTS: The 1970s group comprised 141 consecutive injecting drug users who attended the Brisbane Street Methadone Clinic. The 1990s group comprised 88 consecutive, injecting drug users of European origin who were HCV antibody-positive and attended a primary healthcare facility (the Kirketon Road Centre). MAIN OUTCOME MEASURES: HCV antibody prevalence (1970s); profile of HCV serotypes (1970s and 1990s); and serological evidence of hepatitis A and B. RESULTS: 84% of the 1970s group were HCV antibody-positive, of whom 92% were infected with HCV serotype 1 and 1% with serotype 3. In contrast, in the 1990s group, 69% were infected with HCV serotype 1 and 25% with serotype 3. The HCV-positive subjects from the early group were more likely than those from the recent group to have serological evidence of previous HBV infection. CONCLUSIONS: The high prevalence of HCV among injecting drug users in the 1970s in Australia confirms an epidemic that has been present for at least 25 years. Over this period, the proportion of HCV genotype 1 infections has decreased and genotype 3 infections have emerged.

Adult↗
PubMed2000

Mixed viral infection identified using heteroduplex mobility analysis (HMA).

It is now recognised that mixed viral infection, or infection of an individual with two or more distinct strains of a single viral species, often occurs particularly with RNA viruses. Current methods for detection of mixed infection normally involve genotyping or cloning and DNA sequencing. These methods are not always accurate or sensitive at detecting mixed infection and cannot be used for large numbers of samples. Furthermore subsequent sequence determination of the coinfecting viruses is labour intensive. This paper describes a simple, generic method based upon PCR and heteroduplex mobility analysis (HMA) that can be used to rapidly determine mixed infection with two strains of the same virus. The utility of this method is illustrated with hepatitis C virus (HCV) and TT virus (TTV) as examples. PCR-HMA detected mixed infection in 3 (8%) of 38 sera from intravenous drug users (IVDU) and 28 (30%) of 70 TTV-positive sera from Australia, China, and Vietnam. HMA can also be used to screen recombinant colonies to identify the sequences of the coinfecting viruses. The methods described here could be applied to analyse any PCR product containing two or more divergent sequences, whether derived from viruses, bacteria, or eukaryotic organisms.

Base Sequence↗
PubMed2000

Characterisation of two new gene cassettes, aadA5 and dfrA17.

Escherichia coli INS33 was isolated from the urinary tract of an infected patient. It was resistant to ampicillin, chloramphenicol, spectinomycin, streptomycin, sulfafurazole, tetracycline and trimethoprim. PCR screening revealed the presence of a class 1 integron that harboured two new gene cassettes, designated dfrA17 and aadA5. The new dfrA17 cassette was 91% identical to the known dfrA7 cassette. The aadA5 cassette was 95% identical over the first 830 bp to aadA4, but lacked the IS26 element found at the 3' end of this truncated cassette. Cloning and expression of the cassette region demonstrated that dfrA17 conferred high level resistance to trimethoprim but aadA5 conferred resistance to spectinomycin but not to streptomycin.

Amino Acid Sequence↗
PubMed2000

Human cytomegalovirus strains associated with congenital and perinatal infections.

The genotypes of human cytomegalovirus (HCMV) isolates from pediatric patients differs from those of infected adults in Australia. Genotypes were determined by PCR amplification of glycoprotein B (gB) sequences, with subsequent analysis by restriction fragment length polymorphism, single-stranded conformation polymorphism, heteroduplex mobility analysis and direct DNA sequencing. Restriction fragment length polymorphism analysis of gB showed genotypes gB1 (39%) and gB3 (30%) were more prevalent in infected children and two new genotypes (gB6 and gB7) were found. Single-stranded conformation polymorphism was used to group isolates into 22 further subtypes and suggested longitudinal co-infection or viral mutation was occurring over time. Heteroduplex mobility analysis was found to be the most accurate and concise of the four methods used for genotyping HCMV isolates. DNA sequencing was used to confirm the results obtained from heteroduplex mobility analysis, and identified two isolates that were incorrectly genotyped by restriction fragment length polymorphism analysis. Heteroduplex mobility analysis efficiently genotyped all samples and allowed estimation of sequence variation between isolates. These data suggest certain gB genotypes are associated more commonly with childhood infections, and these differ from strains associated with invasive disease in HIV patients.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Improving permissive infection of human cytomegalovirus in cell culture.

Changes in human cytomegalovirus (HCMV) titre occurring under different conditions were studied using plaque assay. No significant change in titre was found using primary embryonic fibroblasts or primary foreskin fibroblasts, or with the addition of dexamethasone to the medium. Significant increases in titre were found when standard cultures were pre-incubated in medium containing DEAE-dextran and/or calcium chloride. However, DEAE-dextran and/or calcium chloride had no significant effect on HCMV detection using the shell vial assay, possibly because enhancement affects permissive infection, but not surface expression of viral antigens. DEAE-dextran and calcium chloride can be included in the medium of standard cultures as a means of obtaining higher titres of HCMV, and are particularly useful for isolates that are difficult to culture.

Calcium Chloride↗
PubMed2000

Detection of astrovirus gastroenteritis in children.

A commercial enzyme immunoassay (EIA) for the detection of astrovirus antigen was used to detect the virus during a 12-month survey of enteric pathogens in children in outpatient (n = 238) and hospital (n = 176) settings. It was found to have a 100% sensitivity and 98.6% specificity. Nineteen astrovirus isolates were detected and confirmed by northern hybridization, cell culture, and RT-PCR. The virus was detected mainly amongst outpatients although a comparison of the detection rate with that in hospitalised children did not demonstrate a statistically significant difference (p = 0.1347). In contrast, there was a strong association between hospitalization and rotavirus infection (p = 0.0371), and a strong association between infection detected in outpatients and adenovirus infection (p = 0.0193). Strains of astrovirus were sequenced, genotyped and shown to be: type 1 (n = 11), type 3 (n = 1), and type 4 (n = 7). Maximum genetic variation in type 1 isolates was 8.6% and type 4 was 7.8%. Changes did not result in amino acid substitutions.

Astroviridae Infections↗