Melbourne Medical School Collected Works - Research Publications
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ItemHow does temperature influences the development of lactococcosis? Transcriptomic and immunoproteomic in vitro approaches(WILEY, 2017-10)Lactococcus garvieae is the aetiological agent of lactococcosis, a haemorrhagic septicaemia that affects marine and freshwater fish, with special incidence and economic relevance in farmed rainbow trout. Water temperature is one of the most important predisposing factors in the development of lactococcosis outbreaks. Lactococcosis in trout usually occur when water temperatures rise to about 18 °C, while fish carriers remain asymptomatic at temperatures below 13 °C. The aim of this work was to analyse the differences in the complete transcriptome response of L. garvieae grown at 18 °C and at 13 °C and to identify the immunogenic proteins expressed by this bacterium at 18 °C. Our results show that water temperature influences the expression of L. garvieae genes involved in the lysis of part of the bacterial cell population and in the cold response bacterial adaptation. Moreover, the surface immunogenic protein profile at 18 °C suggests an important role of the lysozyme-like enzyme, WxL surface proteins and some putative moonlighting proteins (proteins with more than one function, usually associated with different cellular locations) as virulence factors in L. garvieae. The results of this study could provide insights into the understanding of the virulence mechanisms of L. garvieae in fish.
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ItemGlobal Transcriptome Analysis of Lactococcus garvieae Strains in Response to Temperature(PUBLIC LIBRARY SCIENCE, 2013-11-04)Lactococcus garvieae is an important fish and an opportunistic human pathogen. The genomic sequences of several L. garvieae strains have been recently published, opening the possibility of global studies on the biology of this pathogen. In this study, a whole genome DNA microarray of two strains of L. garvieae was designed and validated. This DNA microarray was used to investigate the effects of growth temperature (18°C and 37°C) on the transcriptome of two clinical strains of L. garvieae that were isolated from fish (Lg8831) and from a human case of septicemia (Lg21881). The transcriptome profiles evidenced a strain-specific response to temperature, which was more evident at 18°C. Among the most significant findings, Lg8831 was found to up-regulate at 18°C several genes encoding different cold-shock and cold-induced proteins involved in an efficient adaptive response of this strain to low-temperature conditions. Another relevant result was the description, for the first time, of respiratory metabolism in L. garvieae, whose gene expression regulation was temperature-dependent in Lg21881. This study provides new insights about how environmental factors such as temperature can affect L. garvieae gene expression. These data could improve our understanding of the regulatory networks and adaptive biology of this important pathogen.
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ItemChanges in the cellular microRNA profile by the intracellular expression of HIV-1 Tat regulator: A potential mechanism for resistance to apoptosis and impaired proliferation in HIV-1 infected CD4+T cells(PUBLIC LIBRARY SCIENCE, 2017-10-02)HIV-1 induces changes in the miRNA expression profile of infected CD4+ T cells that could improve viral replication. HIV-1 regulator Tat modifies the cellular gene expression and has been appointed as an RNA silencing suppressor. Tat is a 101-residue protein codified by two exons that regulates the elongation of viral transcripts. The first exon of Tat (amino acids 1-72) forms the transcriptionally active protein Tat72, but the presence of the second exon (amino acids 73-101) results in a more competent regulatory protein (Tat101) with additional functions. Intracellular, full-length Tat101 induces functional and morphological changes in CD4+ T cells that contribute to HIV-1 pathogenesis such as delay in T-cell proliferation and protection against FasL-mediated apoptosis. But the precise mechanism by which Tat produces these changes remains unknown. We analyzed how the stable expression of intracellular Tat101 and Tat72 modified the miRNA expression profile in Jurkat cells and if this correlated with changes in apoptotic pathways and cell cycle observed in Tat-expressing cells. Specifically, the enhanced expression of hsa-miR-21 and hsa-miR-222 in Jurkat-Tat101 cells was associated with the reduced expression of target mRNAs encoding proteins related to apoptosis and cell cycle such as PTEN, PDCD4 and CDKN1B. We developed Jurkat cells with stable expression of hsa-miR-21 or hsa-miR-222 and observed a similar pattern to Jurkat-Tat101 in resistance to FasL-mediated apoptosis, cell cycle arrest in G2/M and altered cell morphology. Consequently, upregulation of hsa-miR-21 and hsa-miR-222 by Tat may contribute to protect against apoptosis and to anergy observed in HIV-infected CD4+ T cells.
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ItemProgress in Characterizing the Human Exposome: a Key Step for Precision Medicine.(Georg Thieme Verlag KG, 2020-08)OBJECTIVE: Most diseases result from the complex interplay between genetic and environmental factors. The exposome can be defined as a systematic approach to acquire large data sets corresponding to environmental exposures of an individual along her/ his life. The objective of this contribution is to raise awareness within the health informatics community about the importance of dealing with data related to the contribution of environmental factors to individual health, particularly in the context of precision medicine informatics. METHODS: This article summarizes the main findings after a panel organized by the International Medical Informatics Association - Exposome Informatics Working Group held during the last MEDINFO, in Lyon (France) in August 2019. RESULTS: The members of our community presented four initiatives (PULSE, Digital exposome, Cloudy with a chance of pain, Wearable clinics), providing a detailed view of current challenges and accomplishments in processing environmental and social data from a health research perspective. Projects illustrate a wide range of research methods, digital data collection technologies, and analytics and visualization tools. This reinforces the idea that this area is now ready for health informaticians to step in and contribute their expertise, leading the application of informatics strategies to understand environmental health problems. CONCLUSIONS: The featured projects illustrate applications that use exposome data for the investigation of the causes of diseases, health care, patient empowerment, and public health. They offer a rich overview of the expanding range of applications that informatics is finding in the field of environmental health, with potential impact in precision medicine.
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ItemLactococcus garvieae: a small bacteria and a big data world(BIOMED CENTRAL LTD, 2015-12-01)OBJECTIVE: To describe the importance of bioinformatics tools to analyze the big data yielded from new "omics" generation-methods, with the aim of unraveling the biology of the pathogen bacteria Lactococcus garvieae. METHODS: The paper provides the vision of the large volume of data generated from genome sequences, gene expression profiles by microarrays and other experimental methods that require biomedical informatics methods for management and analysis. RESULTS: The use of biomedical informatics methods improves the analysis of big data in order to obtain a comprehensive characterization and understanding of the biology of pathogenic organisms, such as L. garvieae. CONCLUSIONS: The "Big Data" concepts of high volume, veracity and variety are nowadays part of the research in microbiology associated with the use of multiple methods in the "omic" era. The use of biomedical informatics methods is a requisite necessary to improve the analysis of these data.
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ItemMapping Biomedical Vocabularies: A Semi-Automated Term Matching Approach(IOS PRESS, 2014)Biomedical vocabularies vary in scope, and it is often necessary to utilize multiple vocabularies simultaneously in order to cover the full range of concepts relevant to a given biomedical application. However, as the number and size of these resources grow both redundancy (i.e., different vocabularies containing similar terms) and inconsistency (i.e., different terms in multiple vocabularies referring to the same entity) between the vocabularies increase. Therefore, there is a need for automatically aligning vocabularies. In this paper, we explore and propose new methods for detecting probable matches between two vocabularies. The methods build upon existing string similarity functions, enhancing these functions for the context of semi-automated vocabulary matching.