Medicine (St Vincent's) - Research Publications
Now showing items 1-12 of 242
One-step radiosynthesis of 4-nitrophenyl 2-[F-18]fluoropropionate ([F-18]NFP); improved preparation of radiolabeled peptides for PET imaging
The versatile (18) F-labeled prosthetic group, 4-nitrophenyl 2-[(18) F]fluoropropionate ([(18) F]NFP), was synthesized in a single step in 45 min from 4-nitrophenyl 2-bromopropionate, with a decay corrected radiochemical yield of 26.2% ± 2.2%. Employing this improved synthesis of [(18) F]NFP, [(18) F]GalactoRGD - the current 'gold standard' tracer for imaging the expression of αV β3 integrin - was prepared with high specific activity in 90 min and 20% decay corrected radiochemical yield from [(18) F]fluoride.
Circulating T-FH cells, serological memory, and tissue compartmentalization shape human influenza-specific B cell immunity
(AMER ASSOC ADVANCEMENT SCIENCE, 2018-02-14)
Immunization with the inactivated influenza vaccine (IIV) remains the most effective strategy to combat seasonal influenza infections. IIV activates B cells and T follicular helper (TFH) cells and thus engenders antibody-secreting cells and serum antibody titers. However, the cellular events preceding generation of protective immunity in humans are inadequately understood. We undertook an in-depth analysis of B cell and T cell immune responses to IIV in 35 healthy adults. Using recombinant hemagglutinin (rHA) probes to dissect the quantity, phenotype, and isotype of influenza-specific B cells against A/California09-H1N1, A/Switzerland-H3N2, and B/Phuket, we showed that vaccination induced a three-pronged B cell response comprising a transient CXCR5-CXCR3+ antibody-secreting B cell population, CD21hiCD27+ memory B cells, and CD21loCD27+ B cells. Activation of circulating TFH cells correlated with the development of both CD21lo and CD21hi memory B cells. However, preexisting antibodies could limit increases in serum antibody titers. IIV had no marked effect on CD8+, mucosal-associated invariant T, γδ T, and natural killer cell activation. In addition, vaccine-induced B cells were not maintained in peripheral blood at 1 year after vaccination. We provide a dissection of rHA-specific B cells across seven human tissue compartments, showing that influenza-specific memory (CD21hiCD27+) B cells primarily reside within secondary lymphoid tissues and the lungs. Our study suggests that a rational design of universal vaccines needs to consider circulating TFH cells, preexisting serological memory, and tissue compartmentalization for effective B cell immunity, as well as to improve targeting cellular T cell immunity.
Cost savings with a novel algorithm for early detection of systemic sclerosis-related pulmonary arterial hypertension.
(Japan International Cultural Exchange Foundation, 2019)
Pulmonary Arterial Hypertension (PAH) is an important cause of death and disability in Scleroderma (SSc) patients. Yearly screening of all SSc patients with transthoracic echocardiography (TTE) is recommended in international guidelines and currently utilised by the Australian Scleroderma Interest Group (ASIGSTANDARD). Due to the limitations of TTE, the Australian Scleroderma Interest Group (ASIG) developed a new screening algorithm (ASIGPROPOSED) utilizing a serum biomarker, NT-proBNP, in place of TTE, which has been shown to be equally accurate as the current algorithm. The aim of this study was to compare the cost of these two algorithms. The new algorithm resulted in significant yearly cost savings of between AUD$42,913.35 and AUD$84,570 in screening and diagnosis of the ASCS cohort which, if extrapolated to the Australian population, would result in a yearly cost saving of between AUD$367,066 and AUD$725,564. There was no scenario in which the proposed algorithm did not result in a cost saving.
Development and validation of the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI): a novel instrument to quantify organ damage in systemic sclerosis
(BMJ PUBLISHING GROUP, 2019-06-01)
OBJECTIVE: We sought to develop the first Damage Index (DI) in systemic sclerosis (SSc). METHODS: The conceptual definition of 'damage' in SSc was determined through consensus by a working group of the Scleroderma Clinical Trials Consortium (SCTC). Systematic literature review and consultation with patient partners and non-rheumatologist experts produced a list of potential items for inclusion in the DI. These steps were used to reduce the items: (1) Expert members of the SCTC (n=331) were invited to rate the appropriateness of each item for inclusion, using a web-based survey. Items with >60% consensus were retained; (2) Using a prospectively acquired Australian cohort data set of 1568 patients, the univariable relationships between the remaining items and the endpoints of mortality and morbidity (Physical Component Summary score of the Short Form 36) were analysed, and items with p<0.10 were retained; (3) using multivariable regression analysis, coefficients were used to determine a weighted score for each item. The DI was externally validated in a Canadian cohort. RESULTS: Ninety-three (28.1%) complete survey responses were analysed; 58 of 83 items were retained. The univariable relationships with death and/or morbidity endpoints were statistically significant for 22 items, with one additional item forced into the multivariable model by experts due to clinical importance, to create a 23-item weighted SCTC DI (SCTC-DI). The SCTC-DI was predictive of morbidity and mortality in the external cohort. CONCLUSIONS: Through the combined use of consensus and data-driven methods, a 23-item SCTC-DI was developed and retrospectively validated.
Subsets in systemic sclerosis: One size does not fit all
Purpose: Systemic sclerosis (SSc) is a heterogeneous disease that is often divided into subsets to stratify patients and predict prognosis. We hypothesized that individual methods of subsetting would not prognosticate equally well for different outcomes or in patients at different stages of disease. Methods: We subsetted subjects with SSc using three approaches: limited versus diffuse cutaneous SSc (lcSSc, dcSSc); grouped by SSc-specific antibodies; and, grouped using unsupervised clustering. We studied patients with <2 years or between 2–4 years of disease duration, separately. Outcomes were time to death and time to development of (a) SF-36 Physical Component Score <40, (b) forced vital capacity <70% predicted, (c) echocar-diographic pulmonary hypertension, and (d) interstitial lung disease. We used Cox proportional hazards models to determine the ability of the subsets to predict the outcomes of interest, and Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) to compare the performance of the models. Results: In this international, multicentered cohort of over 500 SSc subjects with less than four years of disease duration, none of the three methods of subsetting studied was able to predict all of the outcomes of interest. Different subsetting methods predicted different outcomes within and between each disease duration group. In general, subsetting by skin performed somewhat better than the two other methods, but this was not consistent and there was considerable variability in the models. Conclusions: Subsetting SSc to consistently predict morbidity and mortality in subjects at different stages of disease remains an important challenge.
The epidemiological and pathogenic association of rheumatoid arthritis with atherosclerotic cardiovascular disease.
([Stanmore] : San Lucas Medical, 2011)
Rheumatoid arthritis (RA) is associated with an approximately twofold increased risk of atherosclerotic cardiovascular disease (CVD) including myocardial infarction and stroke. The increased risk of CVD in RA is due to an interplay between traditional risk factors such as hyperlipidemia, hypertension, and smoking and disease-related variables such as the presence of rheumatoid factor and anticyclic citrullinated peptide antibodies, high erythrocyte sedimentation rate, and joint swelling. Systemic inflammation and immune mechanisms form a pathogenic link between synovitis and atherosclerosis in RA. Indeed, high levels of C-reactive protein, an inflammatory marker, predict cardiovascular mortality in RA. Furthermore, the risk of CVD is greatly diminished among patients who respond to disease modifying antirheumatic drugs and biological therapies such as tumor necrosis factor (TNF) alpha antagonists. Through adverse effects on lipid profile and blood glucose level, long-term use of high-dose glucocorticoids in RA also increases cardiovascular risk. However, through control of active disease, glucocorticoids may also indirectly attenuate cardiovascular risk. Through their lipid-lowering and immunomodulatory effects, statins may have a dual benefit in the treatment of patients with RA. However, data on cardiovascular risk reduction in RA through management of traditional risk factors remain scant. Current research efforts are directed toward elucidating the risk factors for CVD in RA and developing strategies to minimize this risk.
Significance of anti-neutrophil cytoplasmic antibodies in systemic sclerosis
BACKGROUND: Up to 12% of patients with systemic sclerosis (SSc) have anti-neutrophil cytoplasmic antibodies (ANCA). However, the majority of these patients do not manifest ANCA-associated vasculitis (AAV) and the significance of ANCA in these patients is unclear. The aim of this study is to determine the prevalence of ANCA in a well-characterised SSc cohort and to examine the association between ANCA and SSc clinical characteristics, other autoantibodies, treatments and mortality. METHODS: Clinical data were obtained from 5 centres in the Australian Scleroderma Cohort Study (ASCS). ANCA positive was defined as the presence of any one or combination of cytoplasmic ANCA (c-ANCA), perinuclear ANCA (p-ANCA), atypical ANCA, anti-myeloperoxidase (anti-MPO) or anti-proteinase-3 (anti-PR3). Associations of demographic and clinical features with ANCA were investigated by logistic or linear regression. Survival analysis was performed using Kaplan-Meyer curves and Cox regression models. RESULTS: Of 1303 patients, 116 (8.9%) were ANCA positive. Anti-PR3 was more common than anti-MPO (13.8% and 11.2% of ANCA-positive patients, respectively). Only 3 ANCA-positive patients had AAV. Anti-Scl-70 was more common in ANCA positive vs ANCA negative (25% vs 12.8%, p < 0.001), anti-MPO positive vs anti-MPO negative (38.5% vs 13.6%, p = 0.006) and anti-PR3 positive vs anti-PR3 negative patients (44.4% vs 13.4%, p < 0.001). A higher prevalence of interstitial lung disease (ILD) was found in the ANCA positive (44.8% vs 21.8%, p < 0.001) and the anti-PR3 positive groups (50.0% vs 23.4%, p = 0.009). In multivariable analysis, ANCA-positive status remained associated with ILD after adjusting for anti-Scl-70 antibodies. Pulmonary embolism (PE) was more common in ANCA-positive patients (8.6% vs 3.0%, p = 0.002) and anti-PR3-positive patients (16.7% vs 3.3%, p = 0.022). ANCA-positive status remained associated with PE in a multivariable analysis adjusting for anti-phospholipid antibodies. Kaplan-Meier analysis revealed increased mortality in ANCA-positive patients (p = 0.006). In Cox regression analysis, ANCA was associated with increased mortality, after adjusting for age and sex. CONCLUSIONS: ANCA is associated with increased prevalence of ILD and PE in SSc. ANCA should be tested in SSc, as it identifies individuals with worse prognosis who require close monitoring for adverse outcomes.
Predictors of mortality in connective tissue disease-associated pulmonary arterial hypertension: a cohort study
(BioMed Central, 2012)
Introduction Pulmonary arterial hypertension (PAH) is a major cause of mortality in connective tissue disease (CTD). We sought to quantify survival and determine factors predictive of mortality in a cohort of patients with CTD-associated PAH (CTD-PAH) in the current era of advanced PAH therapy. Methods Patients with right heart catheter proven CTD-PAH were recruited from six specialised PAH treatment centres across Australia and followed prospectively. Using survival methods including Cox proportional hazards regression, we modelled for all-cause mortality. Independent variables included demographic, clinical and hemodynamic data. Results Among 117 patients (104 (94.9%) with systemic sclerosis), during 2.6 ± 1.8 (mean ± SD) years of follow-up from PAH diagnosis, there were 32 (27.4%) deaths. One-, two- and three-year survivals were 94%, 89% and 73%, respectively. In multiple regression analysis, higher mean right atrial pressure (mRAP) at diagnosis (hazard ratio (HR) = 1.13, 95% CI: 1.04 to 1.24, P = 0.007), lower baseline six-minute walk distance (HR = 0.64, 95% CI: 0.43 to 0.97, P = 0.04), higher baseline World Health Organization functional class (HR = 3.42, 95% CI: 1.25 to 9.36, P = 0.04) and presence of a pericardial effusion (HR = 3.39, 95% CI: 1.07 to 10.68, P = 0.04) were predictive of mortality. Warfarin (HR = 0.20, 95% CI: 0.05 to 0.78, P = 0.02) and combination PAH therapy (HR = 0.20, 95% CI: 0.05 to 0.83, P = 0.03) were protective. Conclusions In this cohort of CTD-PAH patients, three-year survival was 73%. Independent therapeutic predictors of survival included warfarin and combination PAH therapy. Our findings suggest that anticoagulation and combination PAH therapy may improve survival in CTD-PAH. This observation merits further evaluation in randomised controlled trials.
Survival and quality of life in incident systemic sclerosis-related pulmonary arterial hypertension
BACKGROUND: Pulmonary arterial hypertension (PAH) is a leading cause of mortality in systemic sclerosis (SSc). We sought to determine survival, predictors of mortality, and health-related quality of life (HRQoL) related to PAH in a large SSc cohort with PAH. METHODS: We studied consecutive SSc patients with newly diagnosed (incident) World Health Organization (WHO) Group 1 PAH enrolled in a prospective cohort between 2009 and 2015. Survival methods were used to determine age and sex-adjusted standardised mortality ratio (SMR) and years of life lost (YLL), and to identify predictors of mortality. HRQoL was measured using the Short form 36 (SF-36) instrument. RESULTS: Among 132 SSc-PAH patients (112 female (85%); mean age 62 ± 11 years), 60 (45.5%) died, with a median (±IQR) survival time from PAH diagnosis of 4.0 (2.2-6.2) years. Median (±IQR) follow up from study enrolment was 3.8 (1.6-5.8) years. The SMR for patients with SSc-PAH was 5.8 (95% CI 4.3-7.8), with YLL of 15.2 years (95% CI 12.3-18.1). Combination PAH therapy had a survival advantage (p < 0.001) compared with monotherapy, as did anticoagulation compared with no anticoagulation (p < 0.003). Furthermore, combination PAH therapy together with anticoagulation had a survival benefit compared with monotherapy with or without anticoagulation and combination therapy without anticoagulation (hazard ratio 0.28, 95% CI 0.1-0.7). Older age at PAH diagnosis (p = 0.03), mild co-existent interstitial lung disease (ILD) (p = 0.01), worse WHO functional class (p = 0.03) and higher mean pulmonary arterial pressure at PAH diagnosis (p = 0.001), and digital ulcers (p = 0.01) were independent predictors of mortality. CONCLUSIONS: Despite the significant benefits conferred by advanced PAH therapies suggested in this study, the median survival in SSc PAH remains short at only 4 years.