Medicine (RMH) - Research Publications
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ItemNo Preview AvailableAssociations between multidomain modifiable dementia risk factors with AD biomarkers and cognition in middle-aged and older adults.(Elsevier BV, 2024-06)This study aimed to determine associations between modifiable dementia risk factors (MDRF), across domains mood symptomatology, lifestyle behaviors, cardiovascular conditions, cognitive/social engagement, sleep disorders/symptomatology, with cognition, beta-amyloid (Aβ) and tau, and brain volume. Middle-aged/older adults (n=82) enrolled in a sub-study of the Healthy Brain Project completed self-report questionnaires and a neuropsychological battery. Cerebrospinal fluid levels of Aβ 1-42, total tau (t-tau), and phosphorylated tau (p-tau181) (Roche Elecsys), and MRI markers of hippocampal volume and total brain volume were obtained. Participants were classified as no/single domain risk (≤1 domains) or multidomain risk (≥2 domains). Compared to the no/single domain risk group, the multidomain risk group performed worse on the Preclinical Alzheimer's Cognitive Composite (d=0.63, p=.005), and Executive Function (d=0.50, p=.016), and had increased p-tau181 (d=0.47, p=.042) and t-tau (d=0.54, p=.021). In middle-aged/older adults, multidomain MDRFs were related to increases in tau and worse cognition, but not Aβ or brain volume. Findings suggest that increases in AD biomarkers are apparent in midlife, particularly for individuals with greater burden, or variety of MDRFs.
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ItemNo Preview AvailableDecision-making about changing medications across transitions of care: Opportunities for enhanced patient and family engagement.(Elsevier BV, 2024-05)BACKGROUND: Older patients often have complex medication regimens, which change as they move across transitions of care. Engagement of older patients and families in making medication decisions across transitions of care is important for safe and high-quality medication management. AIMS: To explore decision-making between health professionals, older patients and families about medication changes across transitions of care, and to examine how patient and family engagement is enacted in the process of decision-making in relation to these medication changes. METHODS: A focused ethnographic design was undertaken with semi-structured interviews, observations, and reflective focus groups or interviews. Reflexive thematic analysis was conducted on transcribed data. The study was undertaken at a public teaching acute care hospital and a public teaching community hospital in Australia. RESULTS: In all, 182 older patients, 44 family members and 94 health professionals participated. Four themes were conceptualised from the data: different customs and routines, medication challenges, health professional interactions, and patient and family involvement. Environments had differences in their customs and routines, which increased the potential for medication delays or the substitution of unintended medications. Medication challenges included health professionals assuming that patients and families did not need information about regularly prescribed medications. Patients and families were informed about new medications after health professionals had already made decisions to prescribe these medications. Health professionals tended to work in disciplinary silos, and they had views about their role in interacting with patients and families. Patients and families were expected to take the initiative to participate in decision-making about medication changes. CONCLUSIONS: Patient movements across transitions of care can create complex and chaotic medication management situations, which lacks transparency, especially for older patients and their families. A greater focus on pre-emptive and planned discussions about medication changes will contribute to improving patient and family involvement in medication decision-making.
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ItemNo Preview AvailableSelective recording of physiologically evoked neural activity in a mixed autonomic nerve using a minimally invasive array(AIP Publishing LLC, 2023-12-01)Real-time closed-loop control of neuromodulation devices requires long-term monitoring of neural activity in the peripheral nervous system. Although many signal extraction methods exist, few are both clinically viable and designed for extracting small signals from fragile peripheral visceral nerves. Here, we report that our minimally invasive recording and analysis technology extracts low to negative signal to noise ratio (SNR) neural activity from a visceral nerve with a high degree of specificity for fiber type and class. Complex activity was recorded from the rat pelvic nerve that was physiologically evoked during controlled bladder filling and voiding, in an extensively characterized in vivo model that provided an excellent test bed to validate our technology. Urethane-anesthetized male rats (n = 12) were implanted with a four-electrode planar array and the bladder instrumented for continuous-flow cystometry, which measures urodynamic function by recording bladder pressure changes during constant infusion of saline. We demonstrated that differential bipolar recordings and cross-correlation analyses extracts afferent and efferent activity, and discriminated between subpopulations of fibers based on conduction velocity. Integrated Aδ afferent fiber activity correlated with bladder pressure during voiding (r2: 0.66 ± 0.06) and was not affected by activating nociceptive afferents with intravesical capsaicin (r2: 0.59 ± 0.14, P = 0.54, and n = 3). Collectively, these results demonstrate our minimally invasive recording and analysis technology is selective in extracting mixed neural activity with low/negative SNR. Furthermore, integrated afferent activity reliably correlates with bladder pressure and is a promising first step in developing closed-loop technology for bladder control.
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ItemMice with an autism-associated R451C mutation in neuroligin-3 show a cautious but accurate response style in touchscreen attention tasks(WILEY, 2022-01)One of the earliest identifiable features of autism spectrum disorder (ASD) is altered attention. Mice expressing the ASD-associated R451C mutation in synaptic adhesion protein neuroligin-3 (NL3) exhibit impaired reciprocal social interactions and repetitive and restrictive behaviours. The role of this mutation in attentional abnormalities has not been established. We assessed attention in male NL3R451C mice using two well-established tasks in touchscreen chambers. In the 5-choice serial reaction task, rodents were trained to attend to light stimuli that appear in any one of five locations. While no differences between NL3R451C and WT mice were seen in accuracy or omissions, slower response times and quicker reward collection latencies were seen across all training and probe trials. In the rodent continuous-performance test, animals were required to discriminate, and identify a visual target pattern over multiple distractor stimuli. NL3R451C mice displayed enhanced ability to attend to stimuli when task-load was low during training and baseline but lost this advantage when difficulty was increased by altering task parameters in probe trials. NL3R451C mice made less responses to the distractor stimuli, exhibiting lower false alarm rates during all training stages and in probe trials. Slower response times and quicker reward latencies were consistently seen in NL3R451C mice in the rCPT. Slower response times are a major cognitive phenotype reported in ASD patients and are indicative of slower processing speed. Enhanced attention has been shown in a subset of ASD patients and we have demonstrated this phenotype also exists in the NL3R451C mouse model.
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ItemNo Preview AvailableInsulin icodec use in hospital settings: Considerations for once-weekly basal insulin therapy in hospital glycaemic management practice(Elsevier, 2024-05)Diabetes management has benefitted greatly from novel insulin analogues with action profiles that better match individual’s requirements. However, the increased complexity of hospital insulin administration involving multiple practitioners, rapidly changing clinical situations, and therapies causing hyperglycaemia, demands specific consideration for their use. Insulin icodec has an extended duration of action and is beginning to be used in the ambulatory setting. A reassuring early trial experience observed no substantial dysglycaemia in 135 hospitalised participants [ 1 ]. However, the limited glucose measurements informing this observation under intensive clinical trial conditions warrants further consideration of insulin icodec’s implications for real-world hospital settings.
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ItemEvaluating the cost-effectiveness of [18F]FDG-PET/CT for investigation of persistent or recurrent neutropenic fever in high-risk haematology patients(BMC, 2023-12-15)BACKGROUND: A recent randomised trial demonstrated [18F]fluorodeoxyglucose positron-emission tomography in combination with low-dose CT (FDG-PET/CT), compared to standard of care computed tomography (CT) imaging, positively impacted antimicrobial management and outcomes of acute leukaemia and haematopoietic stem cell transplant recipients with persistent and recurrent neutropenic fever. We conducted an economic evaluation from a healthcare perspective alongside the clinical trial. METHODS: Unit costs in Australian dollars were applied to all resources used (antimicrobials, diagnostic tests, ICU and hospital bed days). Effectiveness was measured as number of patients with antimicrobial rationalisation, 6-month mortality and quality-adjusted life years (QALYs) derived from patient-reported trial-based health-related quality-of-life. Generalised linear models were used to analyse costs and outcomes. Incremental cost-effectiveness ratios (ICERs) for all outcomes and net monetary benefit (NMB) for QALYs were calculated. We performed bootstrapping with 1000 replications using the recycled predictions method. RESULTS: The adjusted healthcare costs were lower for FDG-PET/CT (mean $49,563; 95%CI 36,867, 65,133) compared to CT (mean $57,574; 95% CI 44,837, 73,347). The difference in QALYs between the two groups was small (0.001; 95% CI -0.001, 0.004). When simulated 1000 times, FDG-PET/CT was the dominant strategy as it was cheaper with better outcomes than the standard CT group in 74% of simulations. The estimated NMBs at willingness-to-pay thresholds of $50,000 and $100,000 per QALY were positive, thus FDG-PET/CT remained cost-effective at these thresholds. CONCLUSIONS: FDG-PET/CT is cost effective when compared to CT for investigation of persistent/recurrent neutropenic fever in high-risk patients, providing further support for incorporation of FDG-PET/CT into clinical guidelines and funding. TRIAL REGISTRATION: This trial is registered with ClinicalTrials.gov, NCT03429387.
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ItemRisk factors for metachronous colorectal cancer and advanced neoplasia following primary colorectal cancer: a systematic review and meta-analysis(BMC, 2023-11-30)BACKGROUND: Identifying risk factors for metachronous colorectal cancer (CRC) and metachronous advanced neoplasia could be useful for guiding surveillance. We conducted a systematic review and meta-analysis to investigate risk factors for metachronous CRC and advanced neoplasia. METHODS: Searches were conducted in MEDLINE, Embase, Web of Science and Cochrane Central Registry of Controlled Trials for articles (searching period: 1945 to Feburary, 2021) that reported the results of an association between any factor and metachronous advanced neoplasia or metachronous CRC. There were no restrictions on the publication date or language. Random effects models were fitted to estimate the combined association between the risk factors and metachronous CRC or advanced neoplasia. The Risk of Bias In Non-Randomised Studies of Interventions tool (ROBINS-I) was used to assess the risk of bias of included studies. RESULTS: In total, 22 observational studies with 625,208 participants were included in the systematic review and meta-analysis. Of these, 13 studies investigated risk factors for metachronous CRC and 9 for advanced neoplasia. The risks of metachronous CRC or advanced neoplasia were higher if the first CRC was diagnosed in the presence of a synchronous advanced lesion (pooled risk ratio (RR) from 3 studies: 3.61, 95% confidence interval (CI): 1.44-9.05; and pooled RR from 8 studies: 2.77, 95% CI: 2.23-3.43, respectively). The risk of metachronous CRC was lower, but the risk of metachronous advanced neoplasia was higher if the first CRC was distal (compared with proximal) (pooled RR from 3 studies: 0.48, 95% CI: 0.23-0.98; and pooled RR from 2 studies: 2.99, 95% CI: 1.60-5.58 respectively). The risk of metachronous advanced neoplasia increased with age (pooled RR from 3 studies: 1.07 per year of age, 95% CI: 1.03-1.11). There was no evidence that any lifestyle risk factors studied were associated with the risk of metachronous CRC or advanced neoplasia. CONCLUSIONS: The identified risk factors for metachronous CRC and advanced neoplasia might be useful to tailor the existing surveillance guidelines after the first CRC. There were potential limitations due to possible misclassification of the outcome, confounding and risk of bias, and the findings cannot be generalised to high-risk genetic syndrome cases.
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ItemInherited BRCA1 and RNF43 pathogenic variants in a familial colorectal cancer type X family(SPRINGER, 2024-03)Genetic susceptibility to familial colorectal cancer (CRC), including for individuals classified as Familial Colorectal Cancer Type X (FCCTX), remains poorly understood. We describe a multi-generation CRC-affected family segregating pathogenic variants in both BRCA1, a gene associated with breast and ovarian cancer and RNF43, a gene associated with Serrated Polyposis Syndrome (SPS). A single family out of 105 families meeting the criteria for FCCTX (Amsterdam I family history criteria with mismatch repair (MMR)-proficient CRCs) recruited to the Australasian Colorectal Cancer Family Registry (ACCFR; 1998-2008) that underwent whole exome sequencing (WES), was selected for further testing. CRC and polyp tissue from four carriers were molecularly characterized including a single CRC that underwent WES to determine tumor mutational signatures and loss of heterozygosity (LOH) events. Ten carriers of a germline pathogenic variant BRCA1:c.2681_2682delAA p.Lys894ThrfsTer8 and eight carriers of a germline pathogenic variant RNF43:c.988 C > T p.Arg330Ter were identified in this family. Seven members carried both variants, four of which developed CRC. A single carrier of the RNF43 variant met the 2019 World Health Organization (WHO2019) criteria for SPS, developing a BRAF p.V600 wildtype CRC. Loss of the wildtype allele for both BRCA1 and RNF43 variants was observed in three CRC tumors while a LOH event across chromosome 17q encompassing both genes was observed in a CRC. Tumor mutational signature analysis identified the homologous recombination deficiency (HRD)-associated COSMIC signatures SBS3 and ID6 in a CRC for a carrier of both variants. Our findings show digenic inheritance of pathogenic variants in BRCA1 and RNF43 segregating with CRC in a FCCTX family. LOH and evidence of BRCA1-associated HRD supports the importance of both these tumor suppressor genes in CRC tumorigenesis.
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ItemHippocampal cognitive and relational map paradigms explored by multisensory encoding recording with wide-field calcium imaging(CELL PRESS, 2024-01-19)Two major theories have been proposed to explain hippocampal function: cognitive map and the relational theories. They differ in their views on whether hippocampal neurons can process non-spatial information independently. However, the explanatory power of these theories remains unresolved. Additionally, more complex aspects of hippocampal neural population responses to non-spatial stimuli have not been investigated. Here, we used miniaturized fluorescence microscopy to investigate mouse CA1 responses to spatial, visual, auditory modalities, and combinations. We found that while neuronal populations primarily processed spatial information, they also showed strong sensitivity to non-spatial modalities independent of spatial inputs, exhibiting distinct neuronal dynamics and coding patterns. These results provide strong support for the relational theories.
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ItemShould I take aspirin? A qualitative study on the implementation of a decision aid on taking aspirin for bowel cancer prevention(BMJ PUBLISHING GROUP, 2023-11)OBJECTIVES: Australian guidelines recommend 50-70 years consider taking aspirin to reduce their bowel cancer risk. We trialled a decision aid in general practice to facilitate the implementation of these guidelines into clinical practice. This publication reports on the qualitative results from the process evaluation of the trial. We aimed to explore general practitioners' (GPs) and their patients' approach to shared decision-making (SDM) about taking aspirin to prevent bowel cancer and how the decision aids were used in practice. METHODS: Semistructured interviews were conducted with 17 participants who received the decision aid and 12 GPs who participated in the trial between June and November 2021. The interviews were coded inductively, and emerging themes were mapped onto the Revised Programme Theory for SDM. RESULTS: The study highlighted the dynamics of SDM for taking aspirin to prevent bowel cancer. Some participants discussed the decision aid with their GPs as advised prior to taking aspirin, others either took aspirin or dismissed it outright without discussing it with their GPs. Notably, participants' trust in their GPs, and participants' diverse worldviews played pivotal roles in their decisions. Although the decision aid supported SDM for some, it was not always prioritised in a consultation. This was likely impacted during the trial period as the COVID-19 pandemic was the focus for general practice. CONCLUSION: In summary, this study illustrated the complexities of SDM through using a decision aid in general practice to implement the guidelines for low-dose aspirin to prevent bowel cancer. While the decision aid prompted some participants to speak to their GPs, they were also heavily influenced by their unwavering trust in the GPs and their different worldviews. In the face of the COVID-19 pandemic, SDM was not highly prioritised. This study provides insights into the implementation of guidelines into clinical practice and highlights the need for ongoing support and prioritisation of cancer prevention in general practice consultations. TRIAL REGISTRATION NUMBER: ACTRN12620001003965.