41 research outputs found

    Complement peptide C3a receptor 1 promotes optic nerve degeneration in DBA/2J mice.

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    BACKGROUND: The risk of glaucoma increases significantly with age and exposure to elevated intraocular pressure, two factors linked with neuroinflammation. The complement cascade is a complex immune process with many bioactive end-products, including mediators of inflammation. Complement cascade activation has been shown in glaucoma patients and models of glaucoma. However, the function of complement-mediated inflammation in glaucoma is largely untested. Here, the complement peptide C3a receptor 1 was genetically disrupted in DBA/2J mice, an ocular hypertensive model of glaucoma, to test its contribution to neurodegeneration. METHODS: A null allele of C3ar1 was backcrossed into DBA/2J mice. Development of iris disease, ocular hypertension, optic nerve degeneration, retinal ganglion cell activity, loss of RGCs, and myeloid cell infiltration in C3ar1-deficient and sufficient DBA/2J mice were compared across multiple ages. RNA sequencing was performed on microglia from primary culture to determine global effects of C3ar1 on microglia gene expression. RESULTS: Deficiency in C3ar1 lowered the risk of degeneration in ocular hypertensive mice without affecting intraocular pressure elevation at 10.5 months of age. Differences were found in the percentage of mice affected, but not in individual characteristics of disease progression. The protective effect of C3ar1 deficiency was then overcome by additional aging and ocular hypertensive injury. Microglia and other myeloid-derived cells were the primary cells identified that express C3ar1. In the absence of C3ar1, microglial expression of genes associated with neuroinflammation and other immune functions were differentially expressed compared to WT. A network analysis of these data suggested that the IL10 signaling pathway is a major interaction partner of C3AR1 signaling in microglia. CONCLUSIONS: C3AR1 was identified as a damaging neuroinflammatory factor. These data help suggest complement activation causes glaucomatous neurodegeneration through multiple mechanisms, including inflammation. Microglia and infiltrating myeloid cells expressed high levels of C3ar1 and are the primary candidates to mediate its effects. C3AR1 appeared to be a major regulator of microglia reactivity and neuroinflammatory function due to its interaction with IL10 signaling and other immune related pathways. Targeting myeloid-derived cells and C3AR1 signaling with therapies is expected to add to or improve neuroprotective therapeutic strategies

    Pittosporum undulatum as a case study for native species that change range : how to avoid inappropriate responses?

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    During the past two centuries massive land use changes in Australia have altered fire regimes, changed hydrology, increased soil salinity and nutrient levels, and altered abundance and distributions of animals with which native plants interact. Such changes to plant habitats may induce changes in range of indigenous plant species. We need to consider very carefully how to treat native species that naturalise outside their previous ranges. The spread of Pittosporum undulatum in the Sydney region provides a case study for considering approaches to this question

    Cumberland Plain Woodland ecology then and now : interpretations and implications from the work of Robert Brown and others

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    By the time Robert Brown visited western Sydney (1802–1805), its vegetation was already beginning to be affected by settlers' activities. The Cumberland Plain Woodland that occurred on the clay soils has now been extensively cleared and long-term management of remnants for species conservation is of high priority. Robert Brown's collections in the area, together with descriptions by Atkinson, Cunningham and other writers, provide us with valuable information on the vegetation and its floristic composition. Supported by recent site monitoring at Mount Annan Botanic Garden at Campbelltown, we interpret this information in the light of current ecological knowledge and conclude that: • Woodland structure is variable in the short term; therefore seeking to conserve structure exactly as described in the historical literature is not necessarily appropriate. • While the historical literature provides evidence of the broad floristic composition of the Cumberland Plain area overall, it does not provide sufficient detail on individual sites; future management of specific sites must therefore be based on current data. • The evidence suggests relatively few species have become extinct overall, possibly because many species appear to be relatively long-lived, and have mechanisms to survive drought, fire and grazing, though not soil alteration. • Many species, however, are now distributed patchily in localised remnants and rare species are not clustered in a predictable way; species diversity is therefore likely to be lost if further clearing of remnants occurs

    Changes in soil water repellence and its distribution in relation to surface microtopographic units after a low severity fire in eucalypt woodland, Sydney, Australia

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    The distribution and persistence of water repellence was altered by low severity fire and subsequent rain in soil supporting eucalypt woodland on sandstone terrain in Sydney, south-eastern Australia. Water drop penetration times were recorded to depths of 0.08 m in situ 9 months before the experimental fire, immediately after fire, 4 weeks later when rainfall had modified the soil surface but the soil was dry, and 5 weeks after the fire when the soil was moist. Spatial variation in water repellence was high in all cases except immediately after the fire, when soil was almost uniformly strongly repellent to 0.03 m depth, and less uniformly repellent at 0.04–0.06 m depth. Heavy rain moved litter, ash, and mineral soil, modifying the soil surface into microtopographic units including litter dams, microterraces, and other areas with differing proportions of litter, bare soil, and gravel. Post-rain water drop penetration measurements were taken on and beneath these different surface conditions, in order to investigate the possible contribution of water repellence to the formation and maintenance of litter dams and microterraces characteristic of this terrain after fire. Water repellence did not appear to be directly correlated with the presence or absence of surface litter. Results suggest the long-term and spatially variable water repellence found in soils associated with vegetation dominated by eucalypts in Australia is maintained by factors different from those causing extreme and uniform water repellence after fire. Variable water repellence at the soil surface and within the profile may contribute to differential survival of seedlings after fire. The possible breakdown of water repellent compounds formed after fire and the distribution and development of hydrophobic biotic structures including fungal hyphae and proteoid roots need to be investigated.13 page(s

    Assessment of emergency department staff awareness, access and utilisation of advance care directives and goals of care : a cross-sectional survey

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    Background: Emergency department staff awareness, access and implementation of advance care directives and goals of care documents and the related patient consent processes are important but not well understood. Methods: A cross-sectional survey using purposive sampling was undertaken at a tertiary hospital's Emergency Department from 15th March to 26th April 2021. Participants were recruited through online platforms. Pre-validated questionnaires were distributed by email or as QR codes on bulletin boards. Data collected included staff: demographics, knowledge, access and implementation of advance care directives and goals of care documentation. Results: One hundred thirty-four (28%) of 476 targeted participants responded with nursing forming largest group. Results showed that previous attendance of advance care planning education was low at 20%. Familiarity with advance care directive documentations was only 19% while with goals of care document was average. 61 (48%) respondents reported ease of accessing electronic documents and 21 (19%) reported feeling very comfortable discussing and setting goals of care with patients (p = <0.01). Conclusions: Staff awareness of advance care directive was poor, while awareness of goals of care was average. There was no association between advance care directives awareness and staff age group, gender, length of: - professional practice, practice at the study site. © 202
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