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Biomedical subjects

B Currie

Publications and source records attributed to B Currie.

At least 19 recordsLinked to original sources
PubMed2004

Two distinct genotypes of prtF2, encoding a fibronectin binding protein, and evolution of the gene family in Streptococcus pyogenes.

The group A Streptococcus (GAS) is an important pathogen that is responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play an important role in promoting GAS adherence and invasion of host cells. The prtF2 gene encodes an FBP and is present in approximately 60% of GAS strains. In the present study we examined 51 prtF2-positive GAS strains isolated from the Northern Territory of Australia, and here we describe two genotypes of prtF2 which are mutually exclusive. The two genotypes have been identified previously as pfbp and fbaB. We show that these genotypes map to the same chromosomal location within the highly recombinatorial fibronectin-collagen-T antigen (FCT) locus, indicating that they arose from a common ancestor, and in this study these genotypes were designated the pfbp type and the fbaB type. Phylogenetic analysis of seven pfbp types, 14 fbaB types, and 11 prtF2-negative GAS strains by pulsed-field gel electrophoresis (PFGE) produced 32 distinct PFGE patterns. Interpretation of evolution based on the PFGE dendrogram by parsimony suggested that the pfbp type had a recent origin compared to the fbaB type. A comparison of multiple DNA sequences of the pfbp and fbaB types revealed a mosaic pattern for the amino-terminal region of the pfbp types. The fbaB type is generally conserved at the amino terminus but varies in the number of fibronectin binding repeats in the carboxy terminus. Our data also suggest that there is a possible association of the pfbp genotype with sof (84.2%), while the fbaB genotype was found in a majority of the GAS strains negative for sof (90.6%), indicating that these two prtF2 subtypes may be under different selective pressures.

Adhesins, Bacterial↗
PubMed2002

Congenital pulmonary arteriovenous malformations.

We report the rare case of an 11-year-old boy who presented with intractable hypoxaemia and a pulmonary mass. Investigations revealed this to be a pulmonary arteriovenous malformation. It was entirely confined to the right middle lobe and was successfully treated via a right middle lobectomy. The relevant literature with respect to both diagnosis and treatment is reviewed.

Arteriovenous Malformations↗
PubMed2001

Antibody levels to the class I and II epitopes of the M protein and myosin are related to group A streptococcal exposure in endemic populations.

Rheumatic fever (RF)/rheumatic heart disease (RHD) and post-streptococcal glomerulonephritis are thought to be autoimmune diseases, and follow group A streptococcal (GAS) infection. Different GAS M types have been associated with rheumatogenicity or nephritogenicity and categorized into either of two distinct classes (I or II) based on amino acid sequences present within the repeat region ('C' repeats) of the M protein. Sera from ARF patients have previously been shown to contain elevated levels of antibodies to the class I-specific epitope and myosin with the class I-specific antibodies also being cross-reactive to myosin, suggesting a disease association. This study shows that immunoreactivity of the class I-specific peptide and myosin does not differ between controls and acute RF (ARF)/RHD in populations that are highly endemic for GAS, raising the possibility that the association is related to GAS exposure, not the presence of ARF/RHD. Peptide inhibition studies suggest that the class I epitope may be conformational and residue 10 of the peptide is critical for antibody binding. We demonstrate that correlation of antibody levels between the class I and II epitope is due to class II-specific antibodies recognizing a common epitope with class I which is contained within the sequence RDL-ASRE. Our results suggest that antibody prevalence to class I and II epitopes and myosin is associated with GAS exposure, and that antibodies to these epitopes are not an indicator of disease nor a pathogenic factor in endemic populations.

Acute Disease↗
PubMed2001

Murray Valley encephalitis virus surveillance and control initiatives in Australia. National Arbovirus Advisory Committee of the Communicable Diseases Network Australia.

Mechanisms for monitoring Murray Valley encephalitis (MVE) virus activity include surveillance of human cases, surveillance for activity in sentinel animals, monitoring of mosquito vectors and monitoring of weather conditions. The monitoring of human cases is only one possible trigger for public health action and the additional surveillance systems are used in concert to signal the risk of human disease, often before the appearance of human cases. Mosquito vector surveillance includes mosquito trapping for speciation and enumeration of mosquitoes to monitor population sizes and relative composition. Virus isolation from mosquitoes can also be undertaken. Monitoring of weather conditions and vector surveillance determines whether there is a potential for MVE activity to occur. Virus isolation from trapped mosquitoes is necessary to define whether MVE is actually present, but is difficult to deliver in a timely fashion in some jurisdictions. Monitoring of sentinel animals indicates whether MVE transmission to vertebrates is actually occurring. Meteorological surveillance can assist in the prediction of potential MVE virus activity by signalling conditions that have been associated with outbreaks of Murray Valley encephalitis in humans in the past. Predictive models of MVE virus activity for south-eastern Australia have been developed, but due to the infrequency of outbreaks, are yet to be demonstrated as useful for the forecasting of major outbreaks. Surveillance mechanisms vary across the jurisdictions. Surveillance of human disease occurs in all States and Territories by reporting of cases to health authorities. Sentinel flocks of chickens are maintained in 4 jurisdictions (Western Australia, the Northern Territory, Victoria and New South Wales) with collaborations between Western Australia and the Northern Territory. Mosquito monitoring complements the surveillance of sentinel animals in these jurisdictions. In addition, other mosquito monitoring programs exist in other States (including South Australia and Queensland). Public health control measures may include advice to the general public and mosquito management programs to reduce the numbers of both mosquito larvae and adult vectors. Strategic plans for public health action in the event of MVE virus activity are currently developed or being developed in New South Wales, the Northern Territory, South Australia, Western Australia and Victoria. A southern tri-State agreement exists between health departments of New South Wales, Victoria and South Australia and the Commonwealth Department of Health and Aged Care. All partners have agreed to co-operate and provide assistance in predicting and combatting outbreaks of mosquito-borne disease in south-eastern Australia. The newly formed National Arbovirus Advisory Committee is a working party providing advice to the Communicable Diseases Network Australia on arbovirus surveillance and control. Recommendations for further enhancement of national surveillance for Murray Valley encephalitis are described.

Animals↗
PubMed2000

Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand. Australasian Cryptococcal Study Group.

A prospective population-based study was conducted in Australia and New Zealand during 1994-1997 to elucidate the epidemiology of cryptococcosis due to Cryptococcus neoformans var. neoformans (CNVN) and C. neoformans var. gattii (CNVG) and to relate clinical manifestations to host immune status and cryptococcal variety. The mean annual incidence per 10(6) population was 6.6 in Australia and 2.2 in New Zealand. Of 312 episodes, CNVN caused 265 (85%; 98% of the episodes in immunocompromised hosts) and CNVG caused 47 (15%; 44% of the episodes in immunocompetent hosts). The incidence of AIDS-associated cases in Australia declined annually (P<.001). Aborigines in rural or semirural locations (P<.001) and immunocompetent males (P<.001) were at increased risk of CNVG infection. Cryptococcomas in lung or brain were more common in immunocompetent hosts (P< or =.03) in whom there was an association only between lung cryptococcomas and CNVG. An AIDS-associated genetic profile of CNVN serotype A was confirmed by random amplification of polymorphic DNA analysis. Resistance to antifungal drugs was uncommon. The epidemiology of CNVN infection has changed substantially. Clinical manifestations of disease are influenced more strongly by host immune status than by cryptococcal variety.

AIDS-Related Opportunistic Infections↗
PubMed2000

The radiologist says malrotation: does the surgeon operate?

The management of malrotation when it is an incidental finding is unclear. This retrospective study reports an analysis of radiological and operative findings in a series of 71 patients. There were no deaths. We report a false-positive rate of 15% for upper gastrointestinal contrast studies reported as showing malrotation. Our findings and a review of the literature demonstrate that in the asymptomatic child over 2 years of age, the evidence supporting mandatory correction of malrotation is weak.

Child, Preschool↗
PubMed1999

Functional analysis of IgA antibodies specific for a conserved epitope within the M protein of group A streptococci from Australian Aboriginal endemic communities.

The mucosa is one of the initial sites of group A streptococcal (GAS) infection and salivary IgA (sIgA) is thought to be critical to immunity. However, the target epitopes of sIgA and the function of sIgA in GAS immunity, in particular the role of accessory cells and complement, is largely unknown. We studied the aquisition and the function of sIgA specific for a conserved region epitope, p145 (sequence: LRRDLDASREAKKQVEKALE) of the M protein. Peptide 145-specific sIgA is highly prevalent within an Aboriginal population living in an area endemic for GAS and acquisition of p145-specific sIgA increases with age, consistent with a role for such antibodies in immunity to GAS. Human sIgA and IgG specific for p145 were affinity purified and shown to opsonize M5 GAS in vitro. Opsonization could be specifically inhibited by the addition of free p145 to the antibodies during assay. Opsonization of GAS was totally dependent on the presence of both complement and polymorphonuclear leukocytes, and, moreover, affinity-purified p145-specific sIgA was shown to fix complement in the presence of M5 GAS. These data show that mucosal IgA to this conserved region peptide within the M protein has an important role in human immunity against GAS and may be useful in a broad-based cross-protective anti-streptococcal vaccine.

Adolescent↗
PubMed1999

Genetically distinct dog-derived and human-derived Sarcoptes scabiei in scabies-endemic communities in northern Australia.

Overcrowding is a significant factor contributing to endemic infection with Sarcoptes scabiei in human and animal populations. However, since scabies mites from different host species are indistinguishable morphologically, it is unclear whether people can be infected from scabies-infested animals. Molecular fingerprinting was done using three S. scabiei-specific single locus hypervariable microsatellite markers, with a combined total of 70 known alleles. Multilocus analysis of 712 scabies mites from human and dog hosts in Ohio, Panama and Aboriginal communities in northern Australia now shows that genotypes of dog-derived and human-derived scabies cluster by host species rather than by geographic location. Because of the apparent genetic separation between human scabies and dog scabies, control programs for human scabies in endemic areas do not require resources directed against zoonotic infection from dogs.

Alleles↗
PubMed1999

Snakebite?

Explore the source record for details and available documents.

Adult↗
PubMed1998

Evaluation of PCR for diagnosis of melioidosis.

Previously published PCR-based diagnostic tests for melioidosis were evaluated for clinical usefulness. A Burkholderia pseudomallei 16S rRNA-derived primer set had a sensitivity approaching 100% for clinical samples from 22 culture-confirmed cases of melioidosis and enabled diagnosis of 3 culture-negative cases. However, samples from 10 of 30 inpatients from Royal Darwin Hospital with other diagnoses were positive by PCR, giving a specificity of 67% and a positive predictive value of only 70%. Although there are a number of intriguing possible explanations for our results, concerns of inappropriate therapy resulting from a positive result by PCR have led us to forgo the advantage of rapid PCR diagnosis for melioidosis until a better system is validated.

Humans↗