Predation and fire shape the structure and function of ecosystems globally. However, studies exploring interactions between these two processes are rare, especially at large spatial scales. This knowledge gap is significant not only for ecological theory, but also in an applied context, because it limits the ability of landscape managers to predict the outcomes of manipulating fire and predators. We examined the influence of fire on the occurrence of an introduced and widespread mesopredator, the red fox (Vulpes vulpes), in semi-arid Australia. We used two extensive and complimentary datasets collected at two spatial scales. At the landscape-scale, we surveyed red foxes using sand-plots within 28 study landscapes - which incorporated variation in the diversity and proportional extent of fire-age classes - located across a 104 000 km2 study area. At the site-scale, we surveyed red foxes using camera traps at 108 sites stratified along a century-long post-fire chronosequence (0-105 years) within a 6630 km2 study area. Red foxes were widespread both at the landscape and site-scale. Fire did not influence fox distribution at either spatial scale, nor did other environmental variables that we measured. Our results show that red foxes exploit a broad range of environmental conditions within semi-arid Australia. The presence of red foxes throughout much of the landscape is likely to have significant implications for native fauna, particularly in recently burnt habitats where reduced cover may increase prey species' predation risk.
Professionalism is a core competency for residency required by the Accreditation Council of Graduate Medical Education. We sought a means to objectively assess professionalism among internal medicine and transitional year residents.
Anticonvulsant Hypersensitivity Syndrome (AHS) is a rare complication of common drugs used today. It is unusual in that it occurs later than most other drug reactions, about two to six weeks after initiation of the offending agent. It also has a hereditary background unlike most other drug reactions. This reaction is caused by the aromatic amines and causes hepatitis, skin rash, fever, and other systemic organ involvement can occur. The reaction is rare but often fatal, thus the observer should be acutely aware of this in the months following initiation of the agents.
Human embryonic stem cells (hESCs) are located within the inner cell mass of the preimplantation blastocysts. hESCs exhibit two important properties, the ability to generate exact copies of themselves, termed self-renewal, and pluripotency, the ability of stem cells to differentiate into every cell type of the embryo. This means that in theory it may be possible to generate an inexhaustible supply of primary human somatic cells in vitro which are suitable for application in regenerative medicine. Maintaining stem cell self-renewal and eliciting differentiation are dependent on the coordination of a number of signaling pathways which include members of the transforming growth factor beta (TGF?) and Wnt families. The work in our laboratory has focused on the efficient generation of hepatocyte-like cells (HLCs) from hESCs and induced pluripotent stem cells (iPSCs). In order to mimic signaling during primitive streak and endoderm development, we have utilized TGF? and Wnt signaling pathways in vitro. This has resulted in the generation of homogeneous populations of HLCs exhibiting liver specific function. This chapter will focus on TGF? and Wnt signaling pathways and their role in primitive streak, endoderm, and HLC development.
The authors report the case of a 27-year-old male with ventriculoperitoneal shunt (VPS) for hydrocephalus presenting with episodic transient binocular visual loss (TBVL) and headache. Complete physical, bedside shunt examination and funduscopy were unremarkable. Laboratory investigation, shunt series and imaging studies failed to reveal any acute abnormalities. Interrogation of the shunt system identified a valve malfunction which was corrected with resultant symptomatic relief and the patient was discharged home in stable condition. VPS malfunction occurs secondary to infection or mechanical failure such as obstruction, tubing fracture, shunt migration and over drainage. Resultant raised intracranial pressure leads to symptoms of headache, nausea, vomiting and gait abnormalities. Visual defects including blindness has been occasionally reported from shunt malfunction. Rare complications include cerebrospinal fluid oedema, colonic perforation, paraparesis and parkinsonism. TBVL due to shunt malfunction remains an uncommon presentation and requires a high index of clinical suspicion while evaluating these patients.
A clonal cell line that combines both stable hepatic function and proliferation capacity is desirable for in vitro applications that depend on hepatic function, such as pharmacological or toxicological assays and bioartificial liver systems. Here we describe the generation and characterization of a clonal human cell line for in vitro hepatocyte applications.
We report the case of a patient with pulmonary embolism, treated with fondaparinux as bridging therapy until therapeutic levels were achieved on warfarin, who developed a non-traumatic massive retroperitoneal haematoma requiring substantial resuscitation with blood products and arterial embolisation. To our knowledge, this condition has not been reported with therapeutic doses of fondaparinux. Our patient, however, may have been more predisposed to bleeding due to the unpredictable pharmacokinetics of fondaparinux secondary to his morbid obesity, reduced clearance of the drug due to renal insufficiency and concomitant treatment with low dose aspirin and warfarin. Another consideration was the lack of a specific reversing agent for fondaparinux in the setting of a life threatening haemorrhage.
Side population (SP) cells have recently been identified in a number of tissues although their phenotype and functional abilities are poorly understood. Surface marker characterisation and functional assessment of developing liver SP cells might allow for their isolation and manipulation using clinically relevant techniques. It was hypothesised that SP cells are present early during human liver development and contribute to haematopoietic and epithelial lineage generation. Whilst the SP population remained positive for CD34 during the 1st and 2nd trimester, 1st trimester SP cells were more highly enriched for haematopoietic and epithelial progenitor activity than those from the 2nd trimester in vitro. Marker expression and functional similarities indicate that SP cells in developing human liver may share a temporal relationship with oval/progenitor cells, responsible for liver regeneration after massive or chronic hepatic injury. Furthermore, modification of SP integrin expression during development suggests a potential adaptive interaction with niche components such as fibronectin. Improved understanding of developing human liver SP cells will contribute to the generation of novel cell-based therapies for liver disease.
Wild animals in urban environments are exposed to a broad range of human activities that have the potential to disturb their life history and behaviour. Wildlife responses to disturbance can range from emigration to modified behaviour, or elevated stress, but these responses are rarely evaluated in concert. We simultaneously examined population, behavioural and hormonal responses of an urban population of black swans Cygnus atratus before, during and after an annual disturbance event involving large crowds and intense noise, the Australian Formula One Grand Prix. Black swan population numbers were lowest one week before the event and rose gradually over the course of the study, peaking after the event, suggesting that the disturbance does not trigger mass emigration. We also found no difference in the proportion of time spent on key behaviours such as locomotion, foraging, resting or self-maintenance over the course of the study. However, basal and capture stress-induced corticosterone levels showed significant variation, consistent with a modest physiological response. Basal plasma corticosterone levels were highest before the event and decreased over the course of the study. Capture-induced stress levels peaked during the Grand Prix and then also declined over the remainder of the study. Our results suggest that even intensely noisy and apparently disruptive events may have relatively low measurable short-term impact on population numbers, behaviour or physiology in urban populations with apparently high tolerance to anthropogenic disturbance. Nevertheless, the potential long-term impact of such disturbance on reproductive success, individual fitness and population health will need to be carefully evaluated.
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