Publications by authors named "Purdie A"

Background: In response to the overdose crisis, a collaborative group of two community-based organizations, a health authority and a research institute in Vancouver, Canada, implemented a pilot community-based drug checking (CBDC) intervention for sexual and gender minority (SGM) men. This study identified key factors that influenced the implementation of the CBDC intervention, including opportunities and challenges.

Methods: We conducted semi-structured interviews with seven pertinent parties involved in the CBDC, including policymakers, researchers and representatives from community-based organizations.

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Regulation of host miRNA expression is a contested node that controls the host immune response to mycobacterial infection. The host must counter subversive efforts of pathogenic mycobacteria to launch a protective immune response. Here, we examine the role of miR-126 in the zebrafish- infection model and identify a protective role for infection-induced miR-126 through multiple effector pathways.

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A critical hindrance in the development of effective vaccine strategies to combat infectious disease is lack of knowledge about correlates of protection and of the host responses necessary for successful adaptive immunity. Often vaccine formulations are developed by stepwise experimentation, with incomplete investigation of the fundamental mechanisms of protection. Gudair is a commercially available vaccine registered for use in sheep and goats for controlling spread of sub-species (MAP) infections and reduces mortality by up to 90%.

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The cell mediated immune response and ability of immune cells to migrate to the site of infection are both key aspects of protection against many pathogens. Mycobacterium avium subsp. paratuberculosis (MAP) is an intracellular pathogen and the causative agent of paratuberculosis, a chronic wasting disease of ruminants.

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Systemic immunisation delivered subcutaneously is currently used to control paratuberculosis, a chronic enteritis of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). These vaccines do not provide complete protection and a small cohort of animals still succumb to clinical disease. The aim of this study was to assess mycobacterial infection site-specific variations in immune cells in vaccinated sheep that did or did not develop the disease following controlled exposure to MAP.

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Pathogenic mycobacteria including Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne's disease, manipulate host macrophages to persist and cause disease. In mycobacterial infection, highly plastic macrophages, shift between inflammatory M1 and permissive M2 phenotypes which alter the disease outcome and allow bacteria to survive intracellularly.

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Sex and gender matter to health outcomes, but despite repeated commitments to sex-disaggregate data in health policies and programmes, a persistent and substantial absence of such data remains especially in lower-income countries. This represents a missed opportunity for monitoring and identifying gender-responsive, evidence-informed solutions to address a key driver of the pandemic. In this paper we review the availability of national sex-disaggregated surveillance data on COVID-19 and examine trends on the testing-to-outcome pathway.

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Background: Leptospirosis is a zoonotic disease with a worldwide distribution, caused by pathogenic serovars in the genus Leptospira. Feral pigs are known carriers of Leptospira species and pig hunting using dogs is a common recreational activity in Queensland, Australia.

Methodology And Principal Findings: This study aimed to determine the seroprevalence of Leptospira spp.

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Pathogenic mycobacteria actively dysregulate protective host immune signalling pathways during infection to drive the formation of permissive granuloma microenvironments. Dynamic regulation of host microRNA (miRNA) expression is a conserved feature of mycobacterial infections across host-pathogen pairings. Here we examine the role of miR-206 in the zebrafish model of Mycobacterium marinum infection, which allows investigation of the early stages of granuloma formation.

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microRNA (miRNA) are promising candidates for disease biomarkers as they are abundant in circulation, highly stable in biological fluids and may yield diagnostic biomarker signatures. The reported issues with miRNA isolation using traditional RNA reagents necessitates the optimisation of miRNA isolation from challenging samples. In this study we compared six commercial RNA extraction kits to evaluate their ability to isolate miRNA from ovine plasma.

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Paratuberculosis and bovine tuberculosis are two mycobacterial diseases of ruminants which have a considerable impact on livestock health, welfare, and production. These are chronic "iceberg" diseases which take years to manifest and in which many subclinical cases remain undetected. Suggested biomarkers to detect infected or diseased animals are numerous and include cytokines, peptides, and expression of specific genes; however, these do not provide a strong correlation to disease.

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Background: The role played by the humoral immune response in animals vaccinated against a mycobacterial disease such as paratuberculosis, is not well understood. Sheep vaccinated against Mycobacterium avium subsp. paratuberculosis (MAP) can still become infected and in some cases succumb to clinical disease.

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Johne's disease (JD) is a chronic enteritis caused by subspecies (MAP). Current commercial vaccines are effective in reducing the occurrence of clinical disease although vaccinated animals can still become infected and transmit MAP. Many vaccinated sheep develop severe injection site lesions.

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Paratuberculosis in ruminants is caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP) however exposure does not predetermine progression to clinical disease. The pathogenesis incorporates a subclinical phase during which MAP is capable of evading host immune responses through adaptation of host cellular immune mechanisms. Presented are results of transcriptomic analysis of Merino sheep experimentally exposed to MAP and repeatedly sampled over the subclinical phase, identifying genes consistently changed over time in comparison to unexposed controls and associated with different disease outcomes.

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Johne's disease is a chronic wasting disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). Closely related pathogenic mycobacteria such as M. tuberculosis are capable of altering host lipid metabolism, highlighting the need to explore the role of lipid metabolism contributing to intracellular survival.

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Context: Sexually transmitted infections (STI) and mental health and substance use (MHSU) disorders all occur at elevated rates in sexual and gender minorities. These overlapping epidemics, or syndemics, are exacerbated by challenges these same populations face in accessing sexual/gender minority-affirming services. Many publicly funded STI clinics are a low barrier and provide sexual minority-competent care.

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Changes to lipid metabolism are well-characterised consequences of human tuberculosis infection but their functional relevance are not clearly elucidated in these or other host-mycobacterial systems. The zebrafish-Mycobacterium marinum infection model is used extensively to model many aspects of human-M. tuberculosis pathogenesis but has not been widely used to study the role of infection-induced lipid metabolism.

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Pathogenic mycobacteria such as Mycobacterium tuberculosis are capable of utilising cholesterol as a primary carbon-based energy source in vitro but there has been little research examining the significance of cholesterol in vivo. Johne's disease is a chronic enteric disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). This study sought to evaluate the levels of total serum cholesterol in the host following exposure to MAP.

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Host lipid metabolism is an important target for subversion by pathogenic mycobacteria such as Mycobacterium tuberculosis. The appearance of foam cells within the granuloma are well-characterised effects of chronic tuberculosis. The zebrafish-Mycobacterium marinum infection model recapitulates many aspects of human-M.

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Johne's disease (JD) or paratuberculosis is an economically significant, chronic enteropathy of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). Experimental models of JD in cattle are logistically challenging due to the need for long term monitoring, because the clinical disease can take years to manifest. Three trials were undertaken, the largest involving 20 cattle exposed orally to a low dose of C strain MAP and 10 controls studied for 4.

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Experimental trials in the natural host are essential for development and screening of effective vaccines. For chronic diseases of livestock such as paratuberculosis, these can be lengthy and costly in nature. An alternative is to screen vaccines in vitro; however, previous studies have found that vaccine success in vitro in existing screening assays does not translate to in vivo efficacy.

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