Reynolds A.M.,Royal Adelaide Hospital |
Reynolds A.M.,Hanson Institute |
Holmes M.D.,Royal Adelaide Hospital |
Holmes M.D.,Hanson Institute |
And 5 more authors.
European Respiratory Journal | Year: 2012
Pulmonary arterial hypertension (PAH) remains a fatal disease despite modern pharmacotherapy. Mutations in the gene for bone morphogenetic protein receptor type II (BMPR2) lead to reduced BMPR2 expression, which is causally linked to PAH. BMPR2 is predominantly expressed on pulmonary endothelium and has complex interactions with transforming growth factor (TGF)-β signalling mechanisms. Our objectives were to assess the effect on PAH of upregulating BMPR2 by targeted adenoviral BMPR2 gene delivery to the pulmonary vascular endothelium. We used two established rat models of PAH: chronic hypoxia and monocrotaline (MCT). In both hypertensive models, those receiving BMPR2 had less right ventricular hypertrophy, less pulmonary vascular resistance, improved cardiac function and reduced vascular remodelling. In the MCT model, there was an increase in TGF-β, which was prevented by BMPR2 treatment. In vitro, TGF-β1-induced endothelial-mesenchymal transition (EndMT) in human pulmonary microvascular endothelial cells, which was associated with reduced BMPR2 expression. EndMT was partially ameliorated by stimulating BMPR2 signalling with appropriate ligands even in the ongoing presence of TGF-β1. Collectively, these results indicate therapeutic potential for upregulation of the BMPR2 axis in PAH, which may be, in part, mediated by countering the remodelling effects of TGF-β. Copyright©ERS 2012.
Vandyke K.,Hanson Institute |
Vandyke K.,University of Adelaide |
Fitter S.,Hanson Institute |
Dewar A.L.,Hanson Institute |
And 4 more authors.
Blood | Year: 2010
Imatinib mesylate is a rationally designed tyrosine kinase inhibitor that has revolutionized the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. Although the efficacy and tolerability of imatinib are a vast improvement over conventional chemotherapies, the drug exhibits off-target effects. An unanticipated side effect of imatinib therapy is hypophosphatemia and hypocalcemia, which in part has been attributed to drug-mediated changes to renal and gastrointestinal handling of phosphate and calcium. However, emerging data suggest that imatinib also targets cells of the skeleton, stimulating the retention and sequestration of calcium and phosphate to bone, leading to decreased circulating levels of these minerals. The aim of this review is to highlight our current understanding of the mechanisms surrounding the effects of imatinib on the skeleton. In particular, it examines recent studies suggesting that imatinib has direct effects on bone-resorbing osteoclasts and bone-forming osteoblasts through inhibition of c-fms, c-kit, carbonic anhydrase II, and the platelet-derived growth factor receptor. The potential application of imatinib in the treatment of cancer-induced osteolysis will also be discussed. © 2010 by The American Society of Hematology.
Hope C.M.,University of Adelaide |
Grace B.S.,University of Adelaide |
Pilkington K.R.,Hanson Institute |
Coates P.T.,University of Adelaide |
And 2 more authors.
Kidney International | Year: 2014
High regulatory T-cell (Treg) numbers predict recurrent cutaneous squamous cell carcinoma in kidney transplant recipients, and the Treg immune phenotype may identify kidney transplant recipients at risk of developing squamous cell carcinoma and/or solid-organ cancer. To investigate this, a total of 116 kidney transplant recipients, of whom 65 had current or past cancer, were immune-phenotyped and followed up prospectively for a median of 15 months. Higher Treg (CD3+CD4+FOXP3+CD25 Hi CD127 Lo) proportion and numbers significantly increased the odds of developing cancer (odds ratios (95% CI) 1.61 (1.17-2.20) and 1.03 (1.00-1.06), respectively) after adjusting for age, gender, and duration of immunosuppression. Class-switched memory B cells (CD19+CD27+IgD-) had a significant association to cancer, 1.04 (1.00-1.07). Receiver operator characteristic (ROC) curves for squamous cell carcinoma development within 100 days of immune phenotyping were significant for Tregs, memory B cells, and γδ T cells (AUC of 0.78, 0.68, and 0.65, respectively). After cancer resection, Treg, NK cell, and γδ T-cell numbers fell significantly. Immune-phenotype profiles associated with both squamous cell carcinoma and solid-organ cancer in kidney transplant recipients and depended on the presence of cancer tissue. Thus, immune profiling could be used to stratify kidney transplant recipients at risk of developing cancers to identify those who could qualify for prevention therapy. © 2014 International Society of Nephrology.
Helps S.C.,University of Adelaide |
Thornton E.,University of Adelaide |
Kleinig T.J.,University of Adelaide |
Manavis J.,Hanson Institute |
Vink R.,University of Adelaide
Applied Immunohistochemistry and Molecular Morphology | Year: 2012
We describe a method for the automatic, nonsubjective estimation of 3,3′ diaminobenzidine (DAB) in digital images obtained from routine central nervous system immunohistochemistry using freely available, platform-independent public domain image processing software. This technique estimates the amount of antigen visualized but does not measure antigen content directly. Combined with whole brain section high-resolution scanning, a "virtual dissection" (extracting the region of interest) makes it possible to estimate relative antigen content in either subcellular structures, specific brain regions, or in whole tissue sections at magnifications up to 40×. The digital image is processed using Ruifrok and Johnston's color deconvolution method to separate the brown DAB chromogen from the hematoxylin counterstain on a microscope slide. A monochrome image representing the DAB content is then subjected to frequency analysis using NIH-ImageJ and a weighting calculation to estimate the amount of DAB (antigen) as a dimensionless index. The method described produces results that agree with enzyme-linked immunosorbent assays, and is automatic and nonsubjective. The method could easily be adapted to other types of tissue or cell cultures. © 2012 by Lippincott Williams & Wilkins.
Findlay D.M.,University of Adelaide |
Atkins G.J.,Hanson Institute
Osteoporosis International | Year: 2011
It is now well accepted that the molecule receptor activator of NFκB ligand (RANKL) and osteoprotegerin play key roles in regulating physiological and pathological bone turnover. There are a large number of published reports of circulating RANKL levels in both health and pathology. However, interpretation of these data has been elusive, and the relationship between circulating RANKL and RANKL levels in bone is still not clear. This review explores this subject, documenting the possible origins of circulating RANKL and suggesting additional information that is required before serum RANKL levels can provide useful diagnostic or research information. © International Osteoporosis Foundation and National Osteoporosis Foundation 2011.
Hodge S.,Hanson Institute |
Hodge S.,Royal Adelaide Hospital |
Hodge S.,University of Adelaide |
Reynolds P.N.,Hanson Institute |
And 2 more authors.
Respirology | Year: 2012
Background and objective: Chronic inflammation and reduced airways integrity in chronic obstructive pulmonary disease (COPD) potentially results from secondary necrosis as a result of impaired phagocytosis of apoptotic material by airway macrophages, and increased bacterial colonization. We have previously shown that administration of low-dose azithromycin to subjects with COPD improved macrophage phagocytosis of apoptotic airway epithelial cells, reduced inflammation and increased expression of macrophage mannose receptor. Methods: We firstly investigated whether there were defects in the ability of both alveolar (AM) and monocyte-derived macrophages (MDM) to phagocytose bacteria in COPD, as we have previously reported for phagocytosis of apoptotic cells. We then assessed the effects of administration of low-dose azithromycin to COPD patients on the ability of AM and MDM to phagocytose bacteria. Azithromycin (250 mg orally daily for 5 days then 2× weekly (total 12 weeks)) was administered to 11 COPD subjects and phagocytosis of fluorescein isothiocyanate-labelled Escherichia coli assessed by flow cytometry. Results: COPD subjects had a significant defect in the ability of both AM and MDM to phagocytose bacteria that was significantly improved by administration of low-dose azithromycin Conclusions: The data provide further support for the long-term use of low dose azithromycin as an attractive adjunct treatment option for COPD. Improved clearance of both apoptotic cells and bacteria in the airway may have a dual effect; reducing the risk of secondary necrosis and release of toxic cell contents that perpetuate inflammation as well as contributing to a reduction in the rate of exacerbations in COPD. Low-dose azithromycin improves the ability of both AM and MDM to phagocytose bacteria. This further supports the long-term use of low dose azithromycin as an attractive adjunct treatment option for reducing inflammation, bacterial colonization and exacerbation rate in COPD. © 2012 Asian Pacific Society of Respirology.
Brierley S.M.,Hanson Institute |
Brierley S.M.,University of Adelaide
Autonomic Neuroscience: Basic and Clinical | Year: 2010
An organism's ability to perceive mechanical stimuli is vital in determining how it responds to environmental challenges. External mechanosensation is responsible for the senses of touch, hearing, proprioception and aspects of somatic pain. Internally, mechanosensation underlies the initiation of autonomic reflex control and all manner of visceral sensations including chronic pain. Despite our increased knowledge of the molecular identity of invertebrate proteins that convert mechanical stimuli into electrical signals, understanding the complete molecular basis of mammalian mechanotransduction is currently a major challenge. Although the number of candidate molecules that serve as mechanotransducers is ever increasing, debate currently rages as to whether or not they contribute directly or indirectly to mammalian mechanotransduction. Despite these controversies novel molecules have been identified and their contribution to mechanosensation, be it direct or indirect, have improved our understanding of the mechanisms underlying visceral mechanosensation. Moreover, they have provided potential new pharmacological strategies for the control of visceral pain. Crown Copyright © 2009.
Cederholm J.M.,University of South Australia |
Rychkov G.Y.,University of Adelaide |
Bagley C.J.,Hanson Institute |
Bagley C.J.,University of Adelaide |
Bretag A.H.,University of South Australia
International Journal of Biochemistry and Cell Biology | Year: 2010
Proteins of the CLC family are comprised of two subunits, each with its own fast-gated protopore, both of these being regulated simultaneously by a slower common gate. Based on the X-ray crystal structure of a bacterial CLC, the carboxyl side chain of glutamate residue E232 has been proposed as the fast gate of hClC-1, swinging into each pore to close it and competing with chloride. We now show, using hClC-1 mutants expressed in whole-cell patch-clamped HEK293 cells, that elimination of this side chain in the E232Q mutation prevents fast gate closure at all voltages but common gating is also eliminated suggesting that E232 could be the final effector of both fast and common gating. We hypothesise that the conformational information essential for common gating flows between the two E232 protopore residues across the intra-membrane interface, rather than via any cytoplasmic carboxyl-tail interface, to drive common gating. Informed by in silico modelling, we have produced five site-directed mutants that increase the volumes of residues which might be involved in allosteric transfer (A272V, A272L, S289L, V292L and T293L) and assessed them for effects on gating. These mutations could be expected to increase molecular forces between, or torques around, the intimate L287-L287 and I290-I290 contacts that form the pseudo-asymmetric axis of the hClC-1 dimer. Common gating is practically eliminated in V292L and open probability is shifted to more depolarised potentials in A272V, S289L and T293L mainly by altering the voltage dependence of common gating. © 2010 Elsevier Ltd.
Pishas K.I.,University of Adelaide |
Al-Ejeh F.,Queensland Institute of Medical Research |
Zinonos I.,University of Adelaide |
Kumar R.,University of Adelaide |
And 5 more authors.
Clinical Cancer Research | Year: 2011
Purpose: Although mutations in the TP53 gene occur in half of all cancers, approximately 90% of Ewing sarcomas retain a functional wild-type p53. The low frequency of TP53 alterations in Ewing sarcoma makes this tumor type an ideal candidate for p53-targeted therapies. In this study, we have examined the molecular and cellular responses of cultured Ewing sarcoma cell lines following exposure to Nutlin-3a, a recently developed MDM2 antagonist. Experimental Design: The ability of Nutlin-3a to impart apoptosis or cell cycle arrest in a p53-dependent manner was determined in a comprehensive panel of Ewing sarcoma cell lines. The capacity of Nutlin-3a to augment the antitumor activity of MDM4 antagonists and cytotoxic agents currently used in the clinical treatment of Ewing sarcoma was also investigated. Results: Apoptosis was the primary response of wild-type p53 expressing Ewing sarcoma cell lines. The cytotoxicity of Nultin-3a was also synergistic with the chemotherapeutic agents, vincristine, actinomycin D, doxorubicin, and etoposide in a concentration-dependent manner. Significant MDM4 protein overexpression was observed in Ewing sarcoma cell lines of wild-type p53 status, providing a mechanism through which Ewing sarcomas can develop in the absence of TP53 alterations. This study provides the first evidence of synergism between targeted inhibition of MDM2 and MDM4. Conclusion: Our findings suggest that p53-dependent apoptosis is the primary cellular response of Ewing sarcoma cell lines following exposure to Nutlin-3a. Furthermore, Nutlin-3a can synergize with the current Ewing sarcoma chemotherapy protocols, suggesting p53 activation as a novel systemic therapeutic approach for this disease. ©2010 AACR.
Fritzsch B.,University of Iowa |
Dillard M.,St Jude Childrens Research Hospital |
Lavado A.,St Jude Childrens Research Hospital |
Harvey N.L.,St Jude Childrens Research Hospital |
And 2 more authors.
PLoS ONE | Year: 2010
Background: The homeobox gene Prox1 is required for lens, retina, pancreas, liver, and lymphatic vasculature development and is expressed in inner ear supporting cells and neurons. Methodology/Principal Findings: We have investigated the role of Prox1 in the developing mouse ear taking advantage of available standard and conditional Prox1 mutant mouse strains using Tg(Pax2-Cre) and Tg(Nes-Cre). A severe reduction in the size of the canal cristae but not of other vestibular organs or the cochlea was identified in the E18.5 Prox1 Flox/Flox; Tg(Pax2-Cre) mutant ear. In these mutant embryos, hair cell differentiated; however, their distribution pattern was slightly disorganized in the cochlea where the growth of type II nerve fibers to outer hair cells along Prox1 expressing supporting cells was severely disrupted. In the case of Nestin-Cre, we found that newborn Prox1Flox/Flox; Tg(Nestin-Cre) exhibit only a disorganized innervation of outer hair cells despite apparently normal cellular differentiation of the organ of Corti, suggesting a cell-autonomous function of Prox1 in neurons. Conclusions/ Significance: These results identify a dual role of Prox1 during inner ear development; growth of the canal cristae and fiber guidance of Type II fibers along supporting cells in the cochlea. © 2010 Fritzsch et al.