Bernard oBrien Institute of Microsurgery

Melbourne, Australia

Bernard oBrien Institute of Microsurgery

Melbourne, Australia
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Khong S.M.L.,Baker IDI Heart and Diabetes Institute | Andrews K.L.,Baker IDI Heart and Diabetes Institute | Huynh N.N.,Baker IDI Heart and Diabetes Institute | Venardos K.,Baker IDI Heart and Diabetes Institute | And 8 more authors.
British Journal of Pharmacology | Year: 2012

BACKGROUND AND PURPOSE Nitrate tolerance, the loss of vascular responsiveness with continued use of nitrates, remains incompletely understood and is a limitation of these therapeutic agents. Vascular superoxide, generated by uncoupled endothelial NOS (eNOS), may play a role. As arginase competes with eNOS for L-arginine and may exacerbate the production of reactive oxygen species (ROS), we hypothesized that arginase inhibition might reduce nitrate tolerance. EXPERIMENTAL APPROACH Vasodilator responses were measured in aorta from C57Bl/6 and arginase II knockout (argII -/-) mice using myography. Uncoupling of eNOS, determined as eNOS monomer: dimer ratio, was assessed using low-temperature SDS-PAGE and ROS levels were measured using L-012 and lucigenin-enhanced chemiluminescence. KEY RESULTS Repeated application of glyceryl trinitrate (GTN) on aorta isolated from C57Bl/6 mice produced a 32-fold rightward shift of the concentration-response curve. However this rightward shift (or resultant tolerance) was not observed in the presence of the arginase inhibitor (s)-(2-boronethyl)-L-cysteine HCl (BEC; 100 ÂμM) nor in aorta isolated from argII -/- mice. Similar findings were obtained after inducing nitrate tolerance in vivo. Repeated administration of GTN in human umbilical vein endothelial cells induced uncoupling of eNOS from its dimeric state and increased ROS levels, which were reduced with arginase inhibition and exogenous L-arginine. Aortae from GTN tolerant C57Bl/6 mice exhibited increased arginase activity and ROS production, whereas vessels from argII -/- mice did not. CONCLUSION AND IMPLICATIONS Arginase II removal prevents nitrate tolerance. This may be due to decreased uncoupling of eNOS and consequent ROS production. © 2012 The British Pharmacological Society.

Yang S.N.Y.,University of Queensland | Yang S.N.Y.,Monash University | Yang S.N.Y.,Bernard OBrien Institute of Microsurgery | Takeda A.A.S.,University of Queensland | And 6 more authors.
Journal of Biological Chemistry | Year: 2010

Importin-α is the nuclear import receptor that recognizes the classic monopartite and bipartite nuclear localization sequences (cNLSs), which contain one or two clusters of basic amino acids, respectively. Different importin-α paralogs in a single organism are specific for distinct repertoires of cargos. Structural studies revealed that monopartite cNLSs and the C-terminal basic clusters of the bipartite cNLSs bind to the same site on importin-α, termed the major cNLS-binding site. We used an oriented peptide library approach with five degenerate positions to probe the specificity of the major cNLS-binding site in importin-α. We identified the sequences KKKRR, KKKRK, and KKRKK as the optimal sequences for binding to this site for mouse importin-α2, human importin-α1, and human importin-α5, respectively. The crystal structure of mouse importin-α2 with its optimal peptide confirmed the expected binding mode resembling the binding of simian virus 40 large tumor-antigen cNLS. Binding assays confirmed that the peptides containing these sequences bound to the corresponding proteins with low nanomolar affinities. Nuclear import assays showed that the sequences acted as functional cNLSs, with specificity for particular importin-αs. This is the first time that structural information has been linked to an oriented peptide library screening approach for importin-α; the results will contribute to understanding of the sequence determinants of cNLSs, and may help identify as yet unidentified cNLSs in novel proteins. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Seach N.,Monash University | Mattesich M.,Bernard oBrien Institute of Microsurgery | Mattesich M.,Innsbruck Medical University | Abberton K.,Bernard oBrien Institute of Microsurgery | And 6 more authors.
Tissue Engineering - Part C: Methods | Year: 2010

We have previously established a chamber model of tissue engineering that promotes de novo angiogenesis and vascularization of engrafted cells and tissues when combined with an extracellular matrix. Here we demonstrate that the mouse chamber (MC) model can sustain ectopic grafts of murine fetal thymus lobes and, to a limited degree, human pediatric thymus tissue, resulting in de novo T-cell production. Silicone chambers containing Matrigel® and thymus tissues were placed around exposed epigastric vessels and the ends sealed with bone wax, before implantation into the inguinal fat pad of athymic Balb/c nu/nu (nude) mice. Murine, embryonic day 15 (E15) thymus grafts were found to be well vascularized and viable within the MC upon harvest at week 11. In contrast, engraftment of both adult murine and pediatric human thymus tissue was limited, with only one out of the seven human thymus grafts sustaining mature, murine-derived T-cell development. Increased CD4+ and CD8+ T-cell numbers were observed in the peripheral blood of nude mice within 2 weeks after E15 thymus-MC grafts (n=8), compared with nude control mice. Peripheral blood T-cell percentage and subset distribution were comparable to mice receiving conventional thymus kidney capsule grafts. T-cell function of both kidney capsule-and MC-E15 thymus grafts was established via successful rejection of major histocompatibility complex (MHC)-mismatched skin grafts. Sustained growth of fetal thymus tissue in the MC provides an alternative model for the study of thymopoiesis and related applications of T-cell-mediated immunity. © 2010 Mary Ann Liebert, Inc.

Tilkorn D.J.,Bernard oBrien Institute of Microsurgery | Tilkorn D.J.,Ruhr University Bochum | Lokmic Z.,Bernard oBrien Institute of Microsurgery | Lokmic Z.,University of Melbourne | And 8 more authors.
Cells Tissues Organs | Year: 2010

Recreating an environment that supports and promotes fundamental homeostatic mechanisms is a significant challenge in tissue engineering. Optimizing cell survival, proliferation, differentiation, apoptosis and angiogenesis, and providing suitable stromal support and signalling cues are keys to successfully generating clinically useful tissues. Interestingly, those components are often subverted in the cancer setting, where aberrant angiogenesis, cellular proliferation, cell signalling and resistance to apoptosis drive malignant growth. In contrast to tissue engineering, identifying and inhibiting those pathways is a major challenge in cancer research. The recent discovery of adult tissue-specific stem cells has had a major impact on both tissue engineering and cancer research. The unique properties of these cells and their role in tissue and organ repair and regeneration hold great potential for engineering tissue-specific constructs. The emerging body of evidence implicating stem cells and progenitor cells as the source of oncogenic transformation prompts caution when using these cells for tissue-engineering purposes. While tissue engineering and cancer research may be considered as opposed fields of research with regard to their proclaimed goals, the compelling overlap in fundamental pathways underlying these processes suggests that cross-disciplinary research will benefit both fields. In this review article, tissue engineering and cancer research are brought together and explored with regard to discoveries that may be of mutual benefit. Copyright © 2010 S. Karger AG, Basel.

Tourbach S.A.G.J.,University of Melbourne | Tourbach S.A.G.J.,Bernard oBrien Institute of Microsurgery | Hunter-Smith D.,Coastal Plastic Surgery Center | Morrison W.A.,University of Melbourne | Morrison W.A.,Bernard oBrien Institute of Microsurgery
Journal of Plastic Surgery and Hand Surgery | Year: 2011

We report the case of a transgender patient who was referred to our department for management of chronic strictures of his neophalloplasty. We successfully used a free jejunal flap for a long anterior urethral reconstruction. He achieved a patent and functional urethra with satisfactory urinary control and was happy with the cosmetic outcome. © 2011 Informa Healthcare.

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