Publications by authors named "Simon Ruth"

Objectives: Improved life expectancy has led to an ageing population of people living with HIV in most countries. Research on ageing among people living with HIV has predominantly focused on physical and health-related quality of life rather than multidimensional quality of life. We measured quality of life among older people living with HIV in Australia and identified opportunities to guide the development and implementation of appropriate interventions.

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Transcription factors regulate multiple processes during brain development and in the adult brain, from brain patterning to differentiation and maturation of highly specialized neurons as well as establishing and maintaining the functional neuronal connectivity. The members of the zinc-finger transcription factor family Bcl11 are mainly expressed in the hematopoietic and central nervous systems regulating the expression of numerous genes involved in a wide range of pathways. In the brain Bcl11 proteins are required to regulate progenitor cell proliferation as well as differentiation, migration, and functional integration of neural cells.

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Importance: Emerging evidence suggests that risk of bacterial sexually transmitted infections (STIs) increases among gay and bisexual men following initiation of HIV preexposure prophylaxis (PrEP).

Objective: To describe STI incidence and behavioral risk factors among a cohort of predominantly gay and bisexual men who use PrEP, and to explore changes in STI incidence following PrEP commencement.

Design, Setting, And Participants: The Pre-exposure Prophylaxis Expanded (PrEPX) Study, a multisite, open-label intervention study, was nested within the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance (ACCESS) clinic network.

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The transcription factor BCL11B is essential for development of the nervous and the immune system, and Bcl11b deficiency results in structural brain defects, reduced learning capacity, and impaired immune cell development in mice. However, the precise role of BCL11B in humans is largely unexplored, except for a single patient with a BCL11B missense mutation, affected by multisystem anomalies and profound immune deficiency. Using massively parallel sequencing we identified 13 patients bearing heterozygous germline alterations in BCL11B.

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Article Synopsis
  • PrEP (Pre-exposure prophylaxis) is a highly effective HIV prevention method using anti-retroviral therapy, specifically aimed at individuals at high risk, with the potential to reduce local HIV incidence by 25% overall and 30% among gay and bisexual men.
  • The PrEPX study in Victoria, Australia intends to provide generic PrEP to 3,800 individuals over 36 months, involving regular health screenings and data collection to monitor its effectiveness and participant behavior.
  • Important insights gained from this study will inform future PrEP implementation strategies and potentially influence policy regarding subsidized access to PrEP medications in Australia.
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Unlabelled: Background This paper examines a methamphetamine treatment and peer support program for gay men and other men who have sex with men (MSM) who use methamphetamine. Australian MSM use illicit drugs including methamphetamine at significantly higher rates than the broader community.1,2 Methamphetamine rates are higher again amongst HIV positive MSM.

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Structural and functional plasticity of synapses are critical neuronal mechanisms underlying learning and memory. While activity-dependent regulation of synaptic strength has been extensively studied, much less is known about the transcriptional control of synapse maintenance and plasticity. Hippocampal mossy fiber (MF) synapses connect dentate granule cells to CA3 pyramidal neurons and are important for spatial memory formation and consolidation.

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Background: Existing tools for measuring blood-borne virus (BBV) and sexually transmitted infection (STI) transmission risk behaviours in substance use interventions have limited capacity to assess risk behaviours across varied social, cultural and epidemiological contexts; have not evolved alongside HIV treatment and prevention innovations; or accounted for sexual contexts of drug use including among a range of lesbian, gay, bisexual, transgender, intersex and queer (LGBTIQ) sub-communities. The Substance Use and Sex Index (SUSI) is a new brief, simple tool being developed to assess change in HIV and STI risk behaviours for substance use treatment studies.

Methods: A 26-item questionnaire was piloted online among community volunteers (n = 199).

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During neocortical development, neurons undergo polarization, oriented migration, and layer-type-specific differentiation. The transcriptional programs underlying these processes are not completely understood. Here, we show that the transcription factor Bcl11a regulates polarity and migration of upper layer neurons.

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Mouse genetics offers a powerful tool determining the role of specific genes during development. Analyzing the resulting phenotypes by immunohistochemical and molecular methods provides information of potential target genes and signaling pathways. To further elucidate specific regulatory mechanisms requires a system allowing the manipulation of only a small number of cells of a specific tissue by either overexpression, ablation or re-introduction of specific genes and follow their fate during development.

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The development of the dentate gyrus is characterized by distinct phases establishing a durable stem-cell pool required for postnatal and adult neurogenesis. Here, we report that Bcl11b/Ctip2, a zinc finger transcription factor expressed in postmitotic neurons, plays a critical role during postnatal development of the dentate gyrus. Forebrain-specific ablation of Bcl11b uncovers dual phase-specific functions of Bcl11b demonstrated by feedback control of the progenitor cell compartment as well as regulation of granule cell differentiation, leading to impaired spatial learning and memory in mutants.

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Mitogen-activated protein kinase-activated protein (MAPKAP) kinase 5 (MK5) deficiency is associated with reduced extracellular signal-regulated kinase 3 (ERK3) (mitogen-activated protein kinase 6) levels, hence we utilized the MK5 knockout mouse model to analyze the physiological functions of the ERK3/MK5 signaling module. MK5-deficient mice displayed impaired dendritic spine formation in mouse hippocampal neurons in vivo. We performed large-scale interaction screens to understand the neuronal functions of the ERK3/MK5 pathway and identified septin7 (Sept7) as a novel interacting partner of ERK3.

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Dorsal spinal cord neurons receive and integrate somatosensory information provided by neurons located in dorsal root ganglia. Here we demonstrate that dorsal spinal neurons require the Krüppel-C(2)H(2) zinc-finger transcription factor Bcl11a for terminal differentiation and morphogenesis. The disrupted differentiation of dorsal spinal neurons observed in Bcl11a mutant mice interferes with their correct innervation by cutaneous sensory neurons.

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Regulation of energy homeostasis is mainly mediated by factors in the hypothalamus and the brainstem. Understanding these regulatory mechanisms is of great clinical relevance in the treatment of obesity and related diseases. The homeobox gene Sax2 is expressed predominantly in the brainstem, in the vicinity of serotonergic neurons, and in the ventral neural tube starting during early development.

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Mouse models of Wolf-Hirschhorn syndrome.

Am J Med Genet C Semin Med Genet

November 2008

Subtelomeric deletion syndromes represent a significant cause of mental retardation and craniofacial disease. However, for most of these syndromes the pathogenic genes have yet to be identified. Currently there is every indication that identification of these genes will be a slow process if we continue to rely strictly upon clinical data.

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The brain, in particular the hypothalamus and the brainstem, plays a critical role in the regulation of energy homeostasis by incorporating signals from the periphery and translating them into feeding behavior. Here we show that the homeobox gene Sax2, which is expressed predominantly in the brainstem, in the vicinity of serotonergic neurons, contributes to this physiological balance. Sax2 deficiency results in a decrease of fat and glycogen storage, reduced blood glucose levels, and raised serotonin levels in the hindbrain.

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Using genetic inactivation in the mouse, PURA, encoding Pur alpha, is demonstrated to be essential for developmentally-timed dendrite formation in the cerebellum and hippocampus. Comparison of RNA species bound by Pur alpha prompts the hypothesis that Pur alpha functions with non-coding RNA in transport of certain mRNA molecules to sites of translation in dendrites. Pur alpha binds to human BC200 RNA, implicated in dendritic targeting, and this has homologies to 7SL RNA, implicated in compartmentalized translation.

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Intercellular signaling molecules and their receptors, whose expression must be tightly regulated in time and space, coordinate organogenesis. Regulators of intracellular signaling pathways provide an additional level of control. Here we report that loss of the receptor tyrosine kinase (RTK) antagonist, Sprouty1 (Spry1), causes defects in kidney development in mice.

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Homeobox gene transcription factors direct multiple functions during development. They are involved in early patterning of the embryo as well as cell specification, cell differentiation, and organogenesis. Here we describe a previously uncharacterized murine homeobox gene, Sax2, that shows high similarity to the Drosophila S59/slouch and murine Sax1 genes.

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