Melbourne Medical School Collected Works - Research Publications
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ItemFeasibility study of a prototype extended-wear insulin infusion set in adults with type 1 diabetes(WILEY, 2022-03-18)AIM: To assess the feasibility of a prototype insulin infusion set (IIS) for extended wear in adults with type 1 diabetes. MATERIALS AND METHODS: The prototype Capillary Biomedical investigational extended-wear IIS (CBX IIS) incorporates a soft, flexible, reinforced kink-resistant angled nylon-derivative cannula with one distal and three proximal ports to optimize insulin delivery. Twenty adult participants with type 1 diabetes established on insulin pump therapy used the CBX IIS for two 7-day test periods while wearing a Dexcom G5 continuous glucose monitor. RESULTS: Participants were able to wear the CBX IIS for an average of 6.6 ± 1.4 days. Eighty-eight percent (36 of 41) of sets were worn for 7 days. No serious adverse events were reported. Five infusion sets failed prematurely because of: unresolvable hyperglycaemia (three); hyperglycaemia with elevated ketones (one); or infection (one). Median time in range (3.9-10.0 mmol/L) was 62% (54-76). Average glucose levels per day of infusion set wear showed a statistically significant increase over time (p < .001). CONCLUSIONS: Our preliminary observations confirm the tolerability of the prototype CBX IIS for extended wear, albeit with a deterioration in glucose control after the third day.
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ItemEffects of a multicomponent resistance-based exercise program with protein, vitamin D and calcium supplementation on cognition in men with prostate cancer treated with ADT: secondary analysis of a 12-month randomised controlled trial(BMJ PUBLISHING GROUP, 2022-06-01)OBJECTIVES: The aim of this preplanned secondary analysis of a 12-month randomised controlled trial was to investigate the effects of a multicomponent exercise programme combined with daily whey protein, calcium and vitamin D supplementation on cognition in men with prostate cancer treated with androgen deprivation therapy (ADT). DESIGN: 12-month, two-arm, randomised controlled trial. SETTING: University clinical exercise centre. PARTICIPANTS: 70 ADT-treated men were randomised to exercise-training plus supplementation (Ex+ Suppl, n=34) or usual care (control, n=36). INTERVENTION: Men allocated to Ex + Suppl undertook thrice weekly resistance training with weight-bearing exercise training plus daily whey protein (25 g), calcium (1200 mg) and vitamin D (2000 IU) supplementation. PRIMARY AND SECONDARY OUTCOME MEASURES: Cognition was assessed at baseline, 6 and 12 months via a computerised battery (CogState), Trail-making test, Rey auditory-verbal learning test and Digit span. Data were analysed with linear mixed models and an intention-to-treat and prespecified per-protocol approach (exercise-training: ≥66%, nutritional supplement: ≥80%). RESULTS: Sixty (86%) men completed the trial (Ex + Suppl, n=31; control, n=29). Five (7.1%) men were classified as having mild cognitive impairment at baseline. Median (IQR) adherence to the exercise and supplement was 56% (37%-82%) and 91% (66%-97%), respectively. Ex + Suppl had no effect on cognition at any time. CONCLUSIONS: A 12-month multicomponent exercise training and supplementation intervention had no significant effect on cognition in men treated with ADT for prostate cancer compared with usual care. Exercise training adherence below recommended guidelines does not support cognitive health in men treated with ADT for prostate cancer. TRIAL REGISTRATION NUMBER: Australian and New Zealand Clinical Trial Registry (ACTRN12614000317695, registered 25/03/2014) and acknowledged under the Therapeutic Goods Administration Clinical Trial Notification Scheme (CT-2015-CTN-03372-1 v1).
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ItemAssessing the impact of gestational age of donors on the efficacy of amniotic epithelial cell-derived extracellular vesicles in experimental bronchopulmonary dysplasia(BMC, 2022-05-12)BACKGROUND AND RATIONALE: Extracellular vesicles (EVs) are a potential cell-free regenerative medicine. Human amniotic epithelial cells (hAECs) are a viable source of cell therapy for diseases like bronchopulmonary dysplasia (BPD). However, little is known about the impact of gestational age of the donor on the quality of hAEC-derived EVs. AIMS: To determine the impact of gestational age on hAEC-derived EVs in experimental BPD. RESULTS: Term hAEC-derived EVs displayed a significantly higher density of surface epitopes (CD142 and CD133) and induced greater macrophage phagocytosis compared to preterm hAEC-EVs. However, T cell proliferation was more significantly suppressed by preterm hAEC-EVs. Using a model of experimental BPD, we observed that term but not preterm hAEC-EVs improved tissue-to-airspace ratio and septal crest density. While both term and preterm hAEC-EVs reduced the levels of inflammatory cytokines on postnatal day 7, the improvement in lung injury was associated with increased type II alveolar cells which was only observed in term hAEC-EV treatment group. Furthermore, only neonatal term hAEC-EVs reduced airway hyper-responsiveness, mitigated pulmonary hypertension and protected against right ventricular hypertrophy at 6 weeks of age. CONCLUSION: Term hAEC-EVs, but not preterm hAEC-EVs, have therapeutic efficacy in a mouse model of BPD-like lung injury. Therefore, the impact of donor criteria should be considered when applying perinatal cells-derived EV therapy for clinical use.
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ItemIntegrative multi-omics database (iMOMdb) of Asian pregnant women(OXFORD UNIV PRESS, 2022-09-10)Asians are underrepresented across many omics databases, thereby limiting the potential of precision medicine in nearly 60% of the global population. As such, there is a pressing need for multi-omics derived quantitative trait loci (QTLs) to fill the knowledge gap of complex traits in populations of Asian ancestry. Here, we provide the first blood-based multi-omics analysis of Asian pregnant women, constituting high-resolution genotyping (N = 1079), DNA methylation (N = 915) and transcriptome profiling (N = 238). Integrative omics analysis identified 219 154 CpGs associated with cis-DNA methylation QTLs (meQTLs) and 3703 RNAs associated with cis-RNA expression QTLs (eQTLs). Ethnicity was the largest contributor of inter-individual variation across all omics datasets, with 2561 genes identified as hotspots of this variation; 395 of these hotspot genes also contained both ethnicity-specific eQTLs and meQTLs. Gene set enrichment analysis of these ethnicity QTL hotspots showed pathways involved in lipid metabolism, adaptive immune system and carbohydrate metabolism. Pathway validation by profiling the lipidome (~480 lipids) of antenatal plasma (N = 752) and placenta (N = 1042) in the same cohort showed significant lipid differences among Chinese, Malay and Indian women, validating ethnicity-QTL gene effects across different tissue types. To develop deeper insights into the complex traits and benefit future precision medicine research in Asian pregnant women, we developed iMOMdb, an open-access database.
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ItemCardioprotective actions of nitroxyl donor Angeli's salt are preserved in the diabetic heart and vasculature in the face of nitric oxide resistance(WILEY, 2022-04-26)BACKGROUND AND PURPOSE: The risk of fatal cardiovascular events is increased in patients with type 2 diabetes mellitus (T2DM). A major contributor to poor prognosis is impaired nitric oxide (NO•) signalling at the level of tissue responsiveness, termed NO• resistance. This study aimed to determine if T2DM promotes NO• resistance in the heart and vasculature and whether tissue responsiveness to nitroxyl (HNO) is affected. EXPERIMENTAL APPROACH: At 8 weeks of age, male Sprague-Dawley rats commenced a high-fat diet. After 2 weeks, the rats received low-dose streptozotocin (two intraperitoneal injections, 35 mg·kg-1 , over two consecutive days) and continued on the same diet. Twelve weeks later, isolated hearts were Langendorff-perfused to assess responses to the NO• donor diethylamine NONOate (DEA/NO) and the HNO donor Angeli's salt. Isolated mesenteric arteries were utilised to measure vascular responsiveness to the NO• donors sodium nitroprusside (SNP) and DEA/NO, and the HNO donor Angeli's salt. KEY RESULTS: Inotropic, lusitropic and coronary vasodilator responses to DEA/NO were impaired in T2DM hearts, whereas responses to Angeli's salt were preserved or enhanced. Vasorelaxation to Angeli's salt was augmented in T2DM mesenteric arteries, which were hyporesponsive to the relaxant effects of SNP and DEA/NO. CONCLUSION AND IMPLICATIONS: This is the first evidence that inotropic and lusitropic responses are preserved, and NO• resistance in the coronary and mesenteric vasculature is circumvented, by the HNO donor Angeli's salt in T2DM. These findings highlight the cardiovascular therapeutic potential of HNO donors, especially in emergencies such as acute ischaemia or heart failure.
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ItemAstrocytes derived from ASD individuals alter behavior and destabilize neuronal activity through aberrant Ca2+ signaling(SPRINGERNATURE, 2022-04-01)The cellular mechanisms of autism spectrum disorder (ASD) are poorly understood. Cumulative evidence suggests that abnormal synapse function underlies many features of this disease. Astrocytes regulate several key neuronal processes, including the formation of synapses and the modulation of synaptic plasticity. Astrocyte abnormalities have also been identified in the postmortem brain tissue of ASD individuals. However, it remains unclear whether astrocyte pathology plays a mechanistic role in ASD, as opposed to a compensatory response. To address this, we combined stem cell culturing with transplantation techniques to determine disease-specific properties inherent to ASD astrocytes. We demonstrate that ASD astrocytes induce repetitive behavior as well as impair memory and long-term potentiation when transplanted into the healthy mouse brain. These in vivo phenotypes were accompanied by reduced neuronal network activity and spine density caused by ASD astrocytes in hippocampal neurons in vitro. Transplanted ASD astrocytes also exhibit exaggerated Ca2+ fluctuations in chimeric brains. Genetic modulation of evoked Ca2+ responses in ASD astrocytes modulates behavior and neuronal activity deficits. Thus, this study determines that astrocytes derived from ASD iPSCs are sufficient to induce repetitive behavior as well as cognitive deficit, suggesting a previously unrecognized primary role for astrocytes in ASD.
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ItemRaqeeb, Haastrup, and Evans: Seeking Consistency through a Distributive Justice-Based Approach to Limitation of Treatment in the Context of Dispute(CAMBRIDGE UNIV PRESS, 2022-01-01)When is life-sustaining treatment not in the best interests of a minimally conscious child? This is an extremely difficult question that incites seemingly intractable debate. And yet, it is the question courts in England and Wales have set out to answer in disputes about appropriate medical treatment for children.
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ItemEffect of 2D and 3D Culture Microenvironments on Mesenchymal Stem Cell-Derived Extracellular Vesicles Potencies(FRONTIERS MEDIA SA, 2022-02-14)Therapeutic benefits of mesenchymal stem cells (MSCs) are now widely believed to come from their paracrine signalling, i.e. secreted factors such as cytokines, chemokines, and extracellular vesicles (EVs). Cell-free therapy using EVs is an active and emerging field in regenerative medicine. Typical 2D cultures on tissue culture plastic is far removed from the physiological environment of MSCs. The application of 3D cell culture allows MSCs to adapt to their cellular environment which, in turn, influences their paracrine signalling activity. In this study we evaluated the impact of 3D MSCs culture on EVs secretion, cargo proteome composition, and functional assessment in immunomodulatory, anti-inflammatory and anti-fibrotic properties. MSC-EVs from 2D and 3D cultures expressed classical EV markers CD81, CD63, and CD9 with particle diameter of <100 nm. There were distinct changes in immunomodulatory potencies where 3D cultures exhibited reduced indoleamine 2,3-dioxygenase (IDO) activity and significantly reduced macrophage phagocytosis. Administration of 2D and 3D EVs following double dose bleomycin challenge in aged mice showed a marked increase of bodyweight loss in 3D group throughout days 7-28. Histopathological observations of lung tissues in 3D group showed increased collagen deposition, myofibroblast differentiation and leukocytes infiltrations. Assessment of lung mechanics showed 3D group did not improve lung function and instead exhibited increased resistance and tissue damping. Proteome profiling of MSC-EV composition revealed molecular enrichment of EV markers (compared to parental cells) and differential proteome between EVs from 2D and 3D culture condition associated with immune-based and fibrosis/extracellular matrix/membrane organization associated function. This study provides insight into distinct variation in EV protein composition dependent on the cellular microenvironment of the parental cells, which could have implications in their therapeutic effect and potency. Overall, this work suggests that EVs produced from 3D MSC cultures did not enhance typical MSC-EV properties expected from 2D cultures (immunomodulation, anti-fibrotic, anti-inflammatory). The outcome highlights critical differences between MSC-EVs obtained from different culture microenvironments, which should be considered when scaling up MSC culture for clinical manufacturing.
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ItemSchizophrenia is defined by cell-specific neuropathology and multiple neurodevelopmental mechanisms in patient-derived cerebral organoids(SPRINGERNATURE, 2022-03-01)Due to an inability to ethically access developing human brain tissue as well as identify prospective cases, early-arising neurodevelopmental and cell-specific signatures of Schizophrenia (Scz) have remained unknown and thus undefined. To overcome these challenges, we utilized patient-derived induced pluripotent stem cells (iPSCs) to generate 3D cerebral organoids to model neuropathology of Scz during this critical period. We discovered that Scz organoids exhibited ventricular neuropathology resulting in altered progenitor survival and disrupted neurogenesis. This ultimately yielded fewer neurons within developing cortical fields of Scz organoids. Single-cell sequencing revealed that Scz progenitors were specifically depleted of neuronal programming factors leading to a remodeling of cell-lineages, altered differentiation trajectories, and distorted cortical cell-type diversity. While Scz organoids were similar in their macromolecular diversity to organoids generated from healthy controls (Ctrls), four GWAS factors (PTN, COMT, PLCL1, and PODXL) and peptide fragments belonging to the POU-domain transcription factor family (e.g., POU3F2/BRN2) were altered. This revealed that Scz organoids principally differed not in their proteomic diversity, but specifically in their total quantity of disease and neurodevelopmental factors at the molecular level. Single-cell sequencing subsequently identified cell-type specific alterations in neuronal programming factors as well as a developmental switch in neurotrophic growth factor expression, indicating that Scz neuropathology can be encoded on a cell-type-by-cell-type basis. Furthermore, single-cell sequencing also specifically replicated the depletion of BRN2 (POU3F2) and PTN in both Scz progenitors and neurons. Subsequently, in two mechanistic rescue experiments we identified that the transcription factor BRN2 and growth factor PTN operate as mechanistic substrates of neurogenesis and cellular survival, respectively, in Scz organoids. Collectively, our work suggests that multiple mechanisms of Scz exist in patient-derived organoids, and that these disparate mechanisms converge upon primordial brain developmental pathways such as neuronal differentiation, survival, and growth factor support, which may amalgamate to elevate intrinsic risk of Scz.
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ItemExtracellular vesicles carrying HIV-1 Nef induce long-term hyperreactivity of myeloid cells(CELL PRESS, 2022-11-22)A possible explanation for chronic inflammation in HIV-infected individuals treated with anti-retroviral therapy is hyperreactivity of myeloid cells due to a phenomenon called "trained immunity." Here, we demonstrate that human monocyte-derived macrophages originating from monocytes initially treated with extracellular vesicles containing HIV-1 protein Nef (exNef), but differentiating in the absence of exNef, release increased levels of pro-inflammatory cytokines after lipopolysaccharide stimulation. This effect is associated with chromatin changes at the genes involved in inflammation and cholesterol metabolism pathways and upregulation of the lipid rafts and is blocked by methyl-β-cyclodextrin, statin, and an inhibitor of the lipid raft-associated receptor IGF1R. Bone-marrow-derived macrophages from exNef-injected mice, as well as from mice transplanted with bone marrow from exNef-injected animals, produce elevated levels of tumor necrosis factor α (TNF-α) upon stimulation. These phenomena are consistent with exNef-induced trained immunity that may contribute to persistent inflammation and associated co-morbidities in HIV-infected individuals with undetectable HIV load.