Medicine (St Vincent's) - Research Publications
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ItemNo Preview AvailableDefective AMPK regulation of cholesterol metabolism accelerates atherosclerosis by promoting HSPC mobilization and myelopoiesis(ELSEVIER, 2022-07-01)OBJECTIVES: Dysregulation of cholesterol metabolism in the liver and hematopoietic stem and progenitor cells (HSPCs) promotes atherosclerosis development. Previously, it has been shown that HMG-CoA-Reductase (HMGCR), the rate-limiting enzyme in the mevalonate pathway, can be phosphorylated and inactivated by the metabolic stress sensor AMP-activated protein kinase (AMPK). However, the physiological significance of AMPK regulation of HMGCR to atherogenesis has yet to be elucidated. The aim of this study was to determine the role of AMPK/HMGCR axis in the development of atherosclerosis. METHODS: We have generated a novel atherosclerotic-prone mouse model with defects in the AMPK regulation of HMGCR (Apoe-/-/Hmgcr KI mice). Atherosclerotic lesion size, plaque composition, immune cell and lipid profiles were assessed in Apoe-/- and Apoe-/-/Hmgcr KI mice. RESULTS: In this study, we showed that both male and female atherosclerotic-prone mice with a disruption of HMGCR regulation by AMPK (Apoe-/-/Hmgcr KI mice) display increased aortic lesion size concomitant with an increase in plaque-associated macrophages and lipid accumulation. Consistent with this, Apoe-/-/Hmgcr KI mice exhibited an increase in total circulating cholesterol and atherogenic monocytes, Ly6-Chi subset. Mechanistically, increased circulating atherogenic monocytes in Apoe-/-/Hmgcr KI mice was associated with enhanced egress of bone marrow HSPCs and extramedullary myelopoiesis, driven by a combination of elevated circulating 27-hydroxycholesterol and intracellular cholesterol in HSPCs. CONCLUSIONS: Our results uncovered a novel signalling pathway involving AMPK-HMGCR axis in the regulation of cholesterol homeostasis in HSPCs, and that inhibition of this regulatory mechanism accelerates the development and progression of atherosclerosis. These findings provide a molecular basis to support the use of AMPK activators that currently undergoing Phase II clinical trial such as O-3O4 and PXL 770 for reducing atherosclerotic cardiovascular disease risks.
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ItemNo Preview AvailableThe Feasibility of a Web-Based Educational Lifestyle Program for People With Multiple Sclerosis: A Randomized Controlled Trial.(Frontiers Media SA, 2022)Background: Modifiable lifestyle factors are important to aid people with multiple sclerosis in the self-management of their disease. Current self-management programs are limited by their face-to-face mode of delivery but there is immense potential with the internet to deliver these programs effectively. Objective: The aims of this study are to assess the feasibility of a digitalized educational lifestyle self-management program for people with MS. Methods: In this randomized controlled trial, people with MS were randomly allocated to participate in a 6-week tailored web-based educational lifestyle program or 6-week generic standard-care educational course, and were blinded to their allocation. Participants were recruited through multiple sclerosis (MS) Societies in four countries: Australia, New Zealand, Canada, and the United States. The primary outcome was to assess acceptability of the program defined as percentage completion of all modules at 6-weeks post-course commencement. Secondary outcomes included evaluating participant responses to the follow-up survey across three domains: accessibility, learnability, and desirability. Results: Thirty-five participants from Australia, Canada, New Zealand, and the US completed the baseline survey and were randomized. Four participants were deemed ineligible due to incomplete baseline data; therefore, nine out of 15 and eight out of 16 participants completed 100% of the course in the intervention and standard-care arm courses, respectively. Conclusions: This study found that this web-based educational lifestyle program is a feasible means of delivering educational content to people with MS via the internet according to our a priori targets of >40% of participants in the intervention arm, and >25% in the control arm to completing 100% of the course. It is therefore appropriate to evaluate this intervention further in a large, randomized controlled trial. Trial registration: This study was prospectively registered with the Australian New Zealand Clinical Trials Registry (ID: ACTRN12621000245897).
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ItemNo Preview AvailableVitamin D status in patients with frontal fibrosing alopecia: A retrospective study.(Elsevier BV, 2022-06)
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ItemNo Preview AvailableA long-term cohort study of acitretin for prevention of keratinocyte carcinoma in solid organ transplant recipients(WILEY, 2022-03-25)BACKGROUND: Solid organ transplant recipients (SOTR) are at high risk of keratinocyte carcinoma (KC). Long-term evidence for acitretin as chemoprophylaxis in this population is lacking. OBJECTIVE: To determine the benefit of long-term acitretin for KC chemoprevention in SOTR. METHODS: A retrospective cohort study of SOTR treated with acitretin at an Australian transplant dermatology clinic was performed. General estimating equations were used to evaluate change in rates of histologically confirmed KC in the 6-12 months prior to acitretin and following a minimum 6 months of treatment. A control group of patients within the same service was included, comprising SOTR who were not treated with acitretin. RESULTS: Twenty-two patients received acitretin treatment for at least 6 months, eighteen for at least 5 years and four for at least 9 years. The median KC rate pretreatment was 3.31 per year (IQR 1.93, 5.40). There was a significant reduction in the rate of KC in the first year of acitretin treatment (IRR 0.41, 95% CI 0.22, 0.76, P = 0.005), and this effect was observed for 5 years (IRR at 5 years 0.34, 95% CI 0.17, 0.67, P = 0.002). The control group had no statistically significant change in KC rate over time in the study. CONCLUSIONS: Acitretin appears to be well-tolerated and effective in reducing KC in SOTR for at least 5 years. Study limitations include its retrospective nature, small sample size and lack of blinding.
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ItemNo Preview AvailableThe dysfunctional right ventricle: the importance of multi-modality imaging(OXFORD UNIV PRESS, 2022-03-02)Assessment of right ventricular (RV) function is crucial for the evaluation of the dyspnoeic patient and/or with systemic venous congestion and provides powerful prognostic insights. It can be performed using different imaging modalities including standard and advanced echocardiographic techniques, cardiac magnetic resonance imaging, computed tomography, and radionuclide techniques, which should be used in a complementary fashion. Each modality has strengths and weaknesses based on which the choice of their use and in which combination may vary according to the different clinical scenarios as will be detailed in this review. The conclusions from multiple studies using different imaging techniques are concordant: RV function can be reliably assessed and is a critical predictor of clinical outcomes.
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ItemNo Preview AvailableMethod of Assessing Skin Cancerization and Keratoses(TM) (MASCK (TM)): development and photographic validation in multiple anatomical sites of a novel assessment tool intended for clinical evaluation of patients with extensive skin field cancerization(WILEY, 2022-03-22)BACKGROUND: A range of 'field-directed' treatments is available for the management of extensive skin field cancerization (ESFC), but to date, the only validated objective quantitative tools are limited to assessment of actinic keratoses (AKs) affecting the head. AIMS: To develop a versatile quantitative instrument for objective clinical assessment of ESFC and perform initial internal validation across multiple anatomical zones. METHODS: The study comprised instrument development, pilot testing and instrument refinement and two rounds of reliability and inter-rater validation testing. The study was noninterventional and used a convenience sample of de-identified patient photographs selected based on preset criteria. An expert panel developed the instrument and scoring system via a modified Delphi voting process. A sample of 16 healthcare professionals from multiple specialties undertook the pilot testing, and a panel of seven dermatologists were involved in validation testing. Validation was determined by assessment of overall inter-rater agreement using Gwet chance-corrected agreement coefficients (ACs). RESULTS: The instrument produced, called the Method for Assessing Skin Cancer and Keratoses™ (MASCK™), comprises the Skin Field Cancerization Index (SFCIndex), derived from area of skin involvement and AKs (number and thickness), a global assessment score and a cancer-in-zone score, and uses Likert scales for quantitative scoring. The SFCIndex is a composite score comprising the number and thickness of AKs multiplied by area of skin involvement. ACs for the SFCIndex components, the overall SFCIndex score and the global assessment score were > 0.80 (rated 'almost perfect') while the AC for the cancer-in-zone metric was lower (0.33, rated 'fair'). Internal consistency was demonstrated via positive correlation between the overall SFCIndex score and the global assessment score. CONCLUSIONS: Our study found near-perfect agreement in inter-rater reliability when using MASCK to assess the severity of ESFC in multiple anatomical sites. Further validation of this novel instrument is planned to specifically assess its reliability, utility and feasibility in clinical practice.
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ItemNo Preview AvailableMechanism of Bloom syndrome complex assembly required for double Holliday junction dissolution and genome stability(NATL ACAD SCIENCES, 2022-02-08)The RecQ-like helicase BLM cooperates with topoisomerase IIIα, RMI1, and RMI2 in a heterotetrameric complex (the "Bloom syndrome complex") for dissolution of double Holliday junctions, key intermediates in homologous recombination. Mutations in any component of the Bloom syndrome complex can cause genome instability and a highly cancer-prone disorder called Bloom syndrome. Some heterozygous carriers are also predisposed to breast cancer. To understand how the activities of BLM helicase and topoisomerase IIIα are coupled, we purified the active four-subunit complex. Chemical cross-linking and mass spectrometry revealed a unique architecture that links the helicase and topoisomerase domains. Using biochemical experiments, we demonstrated dimerization mediated by the N terminus of BLM with a 2:2:2:2 stoichiometry within the Bloom syndrome complex. We identified mutations that independently abrogate dimerization or association of BLM with RMI1, and we show that both are dysfunctional for dissolution using in vitro assays and cause genome instability and synthetic lethal interactions with GEN1/MUS81 in cells. Truncated BLM can also inhibit the activity of full-length BLM in mixed dimers, suggesting a putative mechanism of dominant-negative action in carriers of BLM truncation alleles. Our results identify critical molecular determinants of Bloom syndrome complex assembly required for double Holliday junction dissolution and maintenance of genome stability.
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ItemNo Preview AvailableChildhood antibiotics are a risk factor for developing Crohn's disease. The ENIGMA international cohort study(WILEY, 2021-08-01)Background and Aim: Environmental factors play a key role in development of Crohn's disease (CD), thought to be mediated by changes in the gut microbiota. We aimed to delineate the potential contribution of antibiotic exposure to subsequent development of CD, across diverse geographical populations. Methods: This case-control study in Australia and three cities in China (Hong Kong, Guangzhou, and Kunming) included four groups: patients with CD, at-risk individuals including non-affected first-degree relatives (FDRs) and household members of CD patients (HM), and unrelated healthy controls (HCs). Environmental risk factors, including childhood antibiotic use and 13 other categories, were assessed using a self-developed questionnaire. Logistic regression and conditional logistic regression were used to determine environmental factors associated with CD development. Results: From 2017 to 2019, a total of 254 patients with CD (mean age: 37.98 ± 13.76 years; 58.3% male), 73 FDR (mean age: 49.35 ± 13.28 years; 46.6% male), 122 HMs (including FDR) (mean age: 45.50 ± 13.25 years; 47.5% male), and 78 HC (mean age: 45.57 ± 11.24; 47.4% male) were included. Comparing CD patients with their FDR and HMs, antibiotic use before 18 years old was a risk factor for CD development (adjusted odds ratio [OR] 3.46, 95% confidence interval [CI] 1.38-8.69; P = 0.008). There were no significant differences in other childhood environmental risk factors between CD and their FDR or HMs. Subgroup analysis showed that antibiotic use <18 years old was a risk factor for CD development in the Chinese (adjusted OR 4.80, 95% CI 1.62-12.24; P = 0.005) but not in Australian populations (OR 1.80, 95% CI 0.33-9.95; P = 0.498). Conclusion: Use of antibiotics <18 years was a risk factor for CD development. Attention should be paid to identifying modifiable environmental risk factors in early childhood, especially in at-risk families.
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ItemObesity in young sudden cardiac death: Rates, clinical features, and insights into people with body mass index >50kg/m2.(Elsevier BV, 2022-09)Objective: To contextualize obesity rates in young sudden cardiac death (SCD) against the age-matched national population, and identify clinical and pathologic features in WHO class II and III obesity. Methods: A prospective state-wide out-of-hospital cardiac arrest registry included all SCDs in Victoria, Australia from 2019-2021. Body mass indices (BMIs) of patients 18-50 years were compared to age-referenced general population. Characteristics of SCD patients with WHO Class II obesity (BMI ≥30kg/m2) and non-obesity (BMI<30kg/m2) were compared. Clinical characteristics of people with BMI>50kg/m2 were assessed. Results: 504 patients were included. Obesity was strongly over-represented in young SCD compared to the age-matched general population (55.0% vs 28.7%, p<0.0001). Obese SCD patients more frequently had hypertension, diabetes and obstructive sleep apnoea (p<0.0001, p=0.009 and p=0.001 respectively), ventricular fibrillation as their arrest rhythm (p=0.008) and left ventricular hypertrophy (LVH) (p<0.0001). Obese patients were less likely to have toxicology positive for illicit substances (22.0% vs 32.6%, p=0.008) or history of alcohol abuse (18.8% vs 26.9%, p=0.030). Patients with BMI>50 kg/m2 represented 8.5% of young SCD. LVH (n=26, 60.5%) was their predominant cause of death and only 10 (9.3%) patients died from coronary disease. Conclusion: Over half of young Australian SCD patients are obese, with all obesity classes over-represented compared to the general population. Obese patients had more cardiac risk factors. Almost two thirds of patients with BMI>50 kg/m2 died from LVH, with fewer than 10% dying from coronary disease.