D.N.J. Hart

Sydney Orthopaedic Research Institute, Sydney, New South Wales, Australia

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Publications (125)455.42 Total impact


  • No preview · Article · May 2012 · Molecular Immunology
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    ABSTRACT: Dendritic cells (DC) are specialized white blood cells that initiate and direct immune responses. Targeting DC surface proteins to deliver liposomes carrying antigens has demonstrated potential for eliciting antigen-specific immune responses. To evaluate this strategy in preclinical studies, we prepared anti-human DEC-205 immunoliposomes (anti-hDEC-205 iLPSM) and compared their uptake by monocyte-derived DC (MoDC) and blood DC (BDC) with conventional liposomes (cLPSM). Antibody conjugation increased the number of immature MoDC taking up liposomes to 70-80%, regardless of the antibody coupled, whereas less than 20% endocytosed cLPSM. Anti-hDEC-205-IgG specifically increased cell uptake by 15% and the total iLPSM uptake six-fold. The non-specific iLPSM uptake was unlikely to be Fc receptor-mediated as excess immunoglobulins failed to block the uptake. Only a small population (7-24%) of mature MoDC took up cLPSM and control iLPSM. In contrast, approximately 70% of mature MoDC took up anti-hDEC-205 iLPSM, endocytosing 10-fold more iLPSM than the control iLPSM. Anti-hDEC-205 iLPSM uptake by CD1c+ BDC was similar to the immature MoDC, but was five-fold increased compared to the control iLPSM. Confocal microscopy confirmed that the anti-hDEC-205 iLPSM were phagocytosed by DC and available for antigen processing. Thus, DEC-205 is an effective target for delivering liposomes to human DC.
    Full-text · Article · Jul 2007 · Vaccine
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    ABSTRACT: The number and function of human T cells in the periphery are regulated by homeostatic signals received from antigen-presenting cells (APCs) and the common gamma chain (gammac) cytokines interleukin (IL)-7 and IL-15. We found that, in the absence of introduced antigen, blood monocytes or myeloid dendritic cells (MDCs) in the presence of IL-7 and IL-15 (IL-7/IL-15) can regulate CD4(+) T memory (Tm) cell numbers by polyclonal cell proliferation. The dynamics of CD4(+) Tm cell proliferation, in the presence of IL-7/IL-15, was dependent on contact with MDCs and to a lesser extent on contact with monocytes. IL-7/IL-15 either alone or combined with monocytes or MDCs enhanced the proportion of CD4(+) Tm cells with activated and effector phenotype and diminished the helper function of CD4(+) Tm cells. These CD4(+) Tm cells, preconditioned with IL-7/IL-15 alone or with monocytes or MDCs and IL-7/IL-15, reduced T cell-dependent immunoglobulin M (IgM) and IgG responses. This appeared to be a contact-dependent effect involving a reduction in antibody-producing CD27(+) B memory cells, but contact-independent suppression by soluble factors also contributed to the antibody-producing capacity of CD27(+) B memory cells. These results indicate that blood monocytes, MDCs and the cytokines IL-7/IL-15 contribute to homeostasis of CD4(+) Tm cells by regulating their number, activation state and helper/suppressor (regulatory) function. In healthy individuals, this mode of regulating CD4(+) Tm cell homeostasis may provide a basis for the control of autoimmune responses.
    Full-text · Article · Apr 2007 · Immunology
  • D.N.J. Hart

    No preview · Article · Apr 2004 · Cytotherapy
  • Derek N.J. Hart · David Jackson · Frank Nestle

    No preview · Chapter · Feb 2003
  • E Gemmell · C L Carter · D N J Hart · K E Drysdale · G J Seymour
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    ABSTRACT: T cells are present in the inflammatory infiltrates of periodontal disease lesions and require antigen presentation by antigen-presenting cells (APCs). While it is still not known whether Th1 or Th2 cells predominate in these lesions, it has been reported that different APCs may induce activation of different T-cell subsets. An immunoperoxidase technique was used to investigate the presence of CD1a+, CMRF-44+, CMRF-58+ and CD83+ dendritic cells, CD14+ macrophages or dendritic cell precursors and CD19+ B cells in gingival biopsies from 21 healthy or gingivitis and 25 periodontitis subjects. The samples were divided into three groups according to the size of infiltrate (group 1, small infiltrates; group 2, medium infiltrates; group 3, extensive infiltrates). The presence of numerous CD1a+ Langerhans cells was noted in the epithelium with no differences between the healthy/gingivitis and periodontitis groups. The percentage of CD83+ dendritic cells in the infiltrates was higher than the percentage of CD1a+, CMRF-44+ or CMRF-58+ dendritic cells. Endothelial cells positive for CD83 were found predominantly in areas adjacent to infiltrating cells, CD83+ dendritic cells being noted in the region of CD83+ endothelium. The percentage of CD14+ cells in the inflammatory infiltrates was similar to that of CD83+ dendritic cells. B cells were the predominant APC in group 2 and 3 tissues. The percentage of B cells in group 3 periodontitis lesions was increased in comparison with group 1 periodontitis tissues and also in comparison with group 3 healthy/gingivitis sections. Functional studies are required to determine the roles of different APC subpopulations in periodontal disease.
    No preview · Article · Jan 2003 · Oral Microbiology and Immunology
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    ABSTRACT: Dendritic cells (DC) provide a bridge between the innate and acquired immune system. HIV exploits the complex pathways of microbial antigen uptake and transport by these cells for initial entry and dissemination. Within DCs, some HIV escapes endolysosomal degradation and antigen presentation pathway to be transferred to CD4+ lymphocytes during activation of T cell-mediated immunity. In skin DC the C type lectin receptors (CLRs), langerin on Langerhans cells (LC), and DC-SIGN and mannose receptor (MR) on dermal DC subsets are all capable of binding HIV gp 120 through its mannose saccharides. Among DCs only the immature DCs in the periphery can bind HIV through CLRs and this enhances HIV fusion with the target cell membrane via CD4/chemokine receptors, or mediates entry into the endolysosomal pathway. Although CLR transfected cell lines and CLR expressing monocyte derived DC (MoDC) can transfer HIV independent of fusion in vitro, observations of DC ex vivo or in vivo show that CLR-enhanced CD4/CCR5-mediated viral fusion appears to be necessary for viral transfer to T cells. Thus HIV utilizes recognition of abundant high mannose glycans on its envelope protein, for binding to CLRs on skin and mucosal DCs, entry via CD4/CCR5 and transport by DCs to CD4+ lymphocytes in lymph nodes, the major site of viral replication.
    No preview · Article · Sep 2002 · Trends in Glycoscience and Glycotechnology
  • José Alejandro López · Derek N J Hart
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    ABSTRACT: Dendritic cells (DCs) initiate and direct the immune response. Their inability to detect danger signals from transformed cells and to generate an effective immunological response may allow cells with a malignant phenotype to evolve into cancers. This defect can be corrected for many cancer types and the immune response boosted to eliminate malignant cells by means of DC-based vaccines/therapies. Rapid advances in our understanding of basic DC physiology and improved methods for DC isolation have made clinical application of DC therapy practical, and encouraging phase I/II results are emerging.
    No preview · Article · Mar 2002 · Current opinion in molecular therapeutics
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    B J Coventry · P-L Lee · D Gibbs · D N J Hart
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    ABSTRACT: Low CD1a-positive putative dendritic cell numbers in human breast cancer has recently been described and may explain the apparent ‘poor immunogenicity’ previously reported in breast cancer. Little attention has been given to dendritic cell activation within the tumour microenvironment, which is another reason why the in-situ immune response may be severely deficient. We have therefore examined CD1a expression as a marker for dendritic cells, together with CMRF-44 and -56 as markers of dendritic cell activation status, in 40 human breast cancers. The results demonstrate few or no CD1a-positive putative dendritic cells and minimal or no expression of the dendritic cell activation markers. Both dendritic cell number and dendritic cell activation appear substantially deficient in human breast cancers, regardless of tumour histological grade. British Journal of Cancer (2002) 86, 546–551. DOI: 10.1038/sj/bjc/6600132 www.bjcancer.com © 2002 Cancer Research UK
    Full-text · Article · Mar 2002 · British Journal of Cancer
  • D.N.J. Hart
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    ABSTRACT: Dendritic cells (DC) are now recognised as a unique leukocyte type, consisting of two or more subsets. The origins and functional inter-relationships of these cells are the subject of intense basic scientific investigation. They play important roles in initiating and directing immune responses, defending the host from pathogens and maintaining self tolerance. Fundamental studies are defining new molecules and mechanisms associated with DC function. The first methods for counting these rare blood cell populations are already providing interesting new clinical data. Indeed, abnormal DC function may contribute to deficiencies in the immune response against malignancies. Phase I trial data suggests that DC-based cancer vaccination protocols may contribute an important new biological approach to cancer therapy. Manipulation of DC to facilitate allogeneic transplantation and even to manage autoimmune disease are likely developments.
    No preview · Article · Dec 2001 · Pathology
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    ABSTRACT: Dendritic cells (DC) are the only antigen-presenting cells that can activate naïve T lymphocytes and initiate a primary immune response. They are also thought to have a role in immune tolerance. DC traffic from the blood to peripheral tissue where they become activated. They then present antigen and the costimulating signals necessary to initiate an immune response. In this study, we investigated the number, subsets, and activation pattern of circulating and intestinal DC from patients with clinically mild ulcerative colitis (UC) or Crohn's disease. Patients were recruited, if they were not taking immunosuppressive therapy, and were assessed for clinical severity of their disease using for UC, the Clinical Activity Index, and for Crohn's disease, the Crohn's Disease Activity Index. Blood CD11c+ and CD11c- DC subsets, expression of costimulatory antigens, CD86 and CD40, and the early differentiation/activation antigen, CMRF44, were enumerated by multicolor flow cytometry of lineage negative (lin- = CD3-, CD19-, CD14-, CD16-) HLA-DR+ DC. These data were compared with age-matched healthy and the disease control groups of chronic noninflammatory GI diseases (cGI), acute noninflammatory GI diseases (aGI), and chronic non-GI inflammation (non-GI). In addition, cryostat sections of colonoscopic biopsies from healthy control patients and inflamed versus noninflamed gut mucosa of inflammatory bowel disease (IBD) patients were examined for CD86+ and CD40+ lin- cells. Twenty-one Crohn's disease and 25 UC patients, with mean Crohn's Disease Activity Index of 98 and Clinical Activity Index of 3.1, and 56 healthy controls, five cGI, five aGI, and six non-GI were studied. CD11c+ and CD11c- DC subsets did not differ significantly between Crohn's, UC, and healthy control groups. Expression of CD86 and CD40 on freshly isolated blood DC from Crohn's patients appeared higher (16.6%, 31%) and was significantly higher in UC (26.6%, 46.3%) versus healthy controls (5.5%, 25%) (p = 0.004, p = 0.012) and non-GI controls (10.2%, 22.8%) (p = 0.012, p = 0.008), but not versus cGI or aGI controls. CD86+ and CD40+ DC were also present in inflamed colonic and ileal mucosa from UC and Crohn's patients but not in noninflamed IBD mucosa or normal mucosa. Expression of the CMRF44 antigen was low on freshly isolated DC, but it was upregulated after 24-h culture on DC from all groups, although significantly less so on DC from UC versus Crohn's or healthy controls (p = 0.024). The CMRF44+ antigen was mainly associated with CD11c+ DC, and in UC was inversely related to the Clinical Activity Index (r = -0.69, p = 0.0002). There is upregulation of costimulatory molecules on blood DC even in very mild IBD but surprisingly, there is divergent expression of the differentiation/activation CMRF44 antigen. Upregulation of costimulatory molecules and divergent expression of CMRF44 in blood DC was also apparent in cGI and aGI but not in non-GI or healthy controls, whereas intestinal CD86+ and CD40+ DC were found only in inflamed mucosa from IBD patients. Persistent or distorted activation of blood DC or divergent regulation of costimulatory and activation antigens may have important implications for gut mucosal immunity and inflammation.
    No preview · Article · Nov 2001 · The American Journal of Gastroenterology
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    ABSTRACT: Background: Dendritic cells (DC) are believed to be one of the first cell types infected during HIV transmission. Recently a single C-type lectin receptor (CLR), DC-SIGN, has been reported to be the predominant receptor on monocyte derived DC (MDDC) rather than CD4. The role of other CLRs in HIV binding and HIV binding by CLRs on other types of DC in vivo is largely unknown. Objectives and study design: Review HIV binding to DC populations, both in vitro and in vivo, in light of the immense interest of a recently re-identified CLR called DC-SIGN. Results and conclusions: From recent work, it is clear that immature MDDC have a complex pattern of HIV gp120 binding. In contrast to other cell types gp120 has the potential to bind to several receptors on DC including CD4 and several types of C type lectin receptor, not just exclusively DC-SIGN. Given the diverse types of DC in vivo future work will need to focus on defining the receptors for HIV binding to these different cell types. Mucosal transmission of HIV in vivo targets immature sessile DCs, including Langerhans cells which lack DC-SIGN. The role of CLRs and DC-SIGN in such transmission remains to be defined. (C) 2001 Elsevier Science B.V. All rights reserved.
    No preview · Article · Nov 2001 · Journal of Clinical Virology
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    C S Ho · J A López · S Vuckovic · C M Pyke · R L Hockey · D N Hart
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    ABSTRACT: Dendritic cells (DCs) are specialized antigen-presenting cells that have the unique ability to initiate a primary immune response. The effect of physiologic stress on circulating blood DCs has thus far not been studied. In this study, we applied a recently developed method of counting blood DCs to test the hypothesis that significant stress to the body such as surgery and exercise might induce measurable changes in the DC numbers, subsets, phenotype, and function. Twenty-six patients scheduled for elective laparoscopic cholecystectomy, 4 for elective hysterectomy, 56 controls, and 5 volunteers who underwent a stress exercise test were enrolled in the study. Absolute DC counts increased acutely (71.7% +/- 11% [SEM], P =.0001) in response to the stress of surgery and dropped below preoperative levels (-25% +/- 14% [SEM], P =.05) on days 2-3. The perioperative DC subset balance remained constant. Interestingly, DC counts changed independently of monocyte counts. Exercise also induced a rise in DC counts but coincidentally with monocyte counts. Surprisingly, no phenotypic or functional activation of DCs was seen in either stress situations in vivo. DCs are rapidly mobilized into the circulation in response to surgical and exercise stress, which may serve to prepare the host's immune defenses against trauma. The independent regulation of the DC and monocyte counts reinforces the distinction between these 2 cell populations.
    Full-text · Article · Aug 2001 · Blood
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    ABSTRACT: Heterogeneous expression of several antigens on the three currently defined tonsil dendritic cell (DC) subsets encouraged us to re-examine tonsil DCs using a new method that minimized DC differentiation and activation during their preparation. Three-color flow cytometry and dual-color immunohistology was used in conjunction with an extensive panel of antibodies to relevant DC-related antigens to analyze lin(-) HLA-DR(+) tonsil DCs. Here we identify, quantify, and locate five tonsil DC subsets based on their relative expression of the HLA-DR, CD11c, CD13, and CD123 antigens. In situ localization identified four of these DC subsets as distinct interdigitating DC populations. These included three new interdigitating DC subsets defined as HLA-DR(hi) CD11c(+) DCs, HLA-DR(mod) CD11c(+) CD13(+) DCs, and HLA-DR(mod) CD11c(-) CD123(-) DCs, as well as the plasmacytoid DCs (HLA-DR(mod) CD11c(-) CD123(+)). These subsets differed in their expression of DC-associated differentiation/activation antigens and co-stimulator molecules including CD83, CMRF-44, CMRF-56, 2-7, CD86, and 4-1BB ligand. The fifth HLA-DR(mod) CD11c(+) DC subset was identified as germinal center DCs, but contrary to previous reports they are redefined as lacking the CD13 antigen. The definition and extensive phenotypic analysis of these five DC subsets in human tonsil extends our understanding of the complexity of DC biology.
    Full-text · Article · Aug 2001 · American Journal Of Pathology
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    B D Hock · M Kato · J L McKenzie · D.N.J. Hart
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    ABSTRACT: CD83 is an inducible glycoprotein expressed predominantly by dendritic cells (DC) and B lymphocytes. Expression of membrane CD83 (mCD83) is widely used as a marker of differentiated/activated DC but its function and ligand(s) are presently unknown. We report the existence of a soluble form of CD83 (sCD83). Using both a sCD83-specific ELISA and Western blotting, we could demonstrate the release of sCD83 by mCD83(+) B cell and Hodgkin's disease-derived cell lines, but not mCD83(-) cells. Inhibition of de novo protein synthesis did not affect the release of sCD83 during short-term (2 h) culture of cell lines although mCD83 expression was significantly reduced, suggesting sCD83 is generated by the release of mCD83. Isolated tonsillar B lymphocytes and monocyte-derived DC, which are mCD83(low), released only low levels of sCD83 during culture. However, the differentiation/activation of these populations both up-regulated mCD83 and increased sCD83 release significantly. Analysis of sera from normal donors demonstrated the presence of low levels (121 +/- 3.6 pg/ml) of circulating sCD83. Further studies utilizing purified sCD83 and the analysis of sCD83 levels in disease may provide clues to the function and ligand(s) of CD83.
    Full-text · Article · Aug 2001 · International Immunology
  • G J Clark · B Cooper · S Fitzpatrick · B J Green · D N Hart
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    ABSTRACT: The immunoregulatory signaling (IRS) family includes several molecules, which play major roles in the regulation of the immune response. The CMRF-35A and CMRF-35H molecules are two new members of the IRS family of molecules, that are found on a wide variety of haemopoietic lineages. The extracellular functional interactions of these molecules is presently unknown, although CMRF-35H can initiate an inhibitory signal and is internalized when cross-linked. In this paper, we described the gene structure for the CMRF-35A gene and its localization to human chromosome 17. The gene consists of four exons spanning approximately 4.5 kb. Exon 1 encodes the 5' untranslated region and leader sequence, exon 2 encodes the immunoglobulin (Ig)-like domain, exon 3 encodes the membrane proximal region and exon 4 encodes the transmembrane region, the cytoplasmic tail and the 3' untranslated region. A region in the 5' flanking sequence of the CMRF-35A gene, that promoted expression of a reporter gene was identified. The genes for the CMRF-35A and CMRF-35H molecules are closely linked on chromosome 17. Similarity between the Ig-like exons and the preceding intron of the two genes suggests exon duplication was involved in their evolution. We also identified a further member of the CMRF-35 family, the CMRF-35J pseudogene. This gene appears to have arisen by gene duplication of the CMRF-35A gene. These three loci - the CMRF-35A, CMRF-35J and CMRF-35H genes-form a new complex of IRS genes on chromosome 17.
    No preview · Article · Jun 2001 · Tissue Antigens
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    ABSTRACT: Dendritic cells (DC) are potent antigen-presenting cells and understanding their mechanisms of antigen uptake is important for loading DC with antigen for immunotherapy. The multilectin receptors, DEC-205 and macrophage mannose receptor (MMR), are potential antigen-uptake receptors; therefore, we examined their expression and FITC-dextran uptake by various human DC preparations. The RT-PCR analysis detected low levels of DEC-205 mRNA in immature blood DC, Langerhans cells (LC) and immature monocyte-derived DC (Mo-DC). Its mRNA expression increased markedly upon activation, indicating that DEC-205 is an activation-associated molecule. In Mo-DC, the expression of cell-surface DEC-205 increased markedly during maturation. In blood DC, however, the cell-surface expression of DEC-205 did not change during activation, suggesting the presence of a large intracellular pool of DEC-205 or post-transcriptional regulation. Immature Mo-DC expressed abundant MMR, but its expression diminished upon maturation. Blood DC and LC did not express detectable levels of the MMR. FITC-dextran uptake by both immature and activated blood DC was 30- to 70-fold less than that of LC, immature Mo-DC and macrophages. In contrast to immature Mo-DC, the FITC-dextran uptake by LC was not inhibited effectively by mannose, an inhibitor for MMR-mediated FITC-dextran uptake. Thus, unlike Mo-DC, blood DC and LC do not use the MMR for carbohydrate-conjugated antigen uptake and alternative receptors may yet be defined on these DC. Therefore, DEC-205 may have a different specificity as an antigen uptake receptor or contribute to an alternative DC function.
    Preview · Article · Dec 2000 · International Immunology
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    ABSTRACT: Cardiac failure is a known complication of haemopoietic stem cell transplantation (HSCT) and is often difficult to diagnose as patients may have multiple medical problems. Since brain natriuretic peptide (BNP) is largely a hormone of cardiac ventricular origin and is released early in the course of ventricular dysfunction, we have examined the value of serial plasma BNP levels for detecting cardiac failure in patients undergoing cytotoxic conditioning for HSCT. Fifteen patients undergoing HSCT were evaluated (10 undergoing autologous HSCT; five undergoing allogeneic HSCT). BNP was measured by radioimmunoassay prior to therapy and weekly for 5 weeks. Seven patients had a significant rise in BNP level (above a previously established threshold of 43 pmol/l associated with cardiac failure), occurring 1-4 weeks post commencement of conditioning. In three of these patients, cardiac failure was subsequently diagnosed clinically 3, 9 and 23 days after a BNP level of 43 pmol/l had been detected. These three patients had the highest peak BNP levels for the group and in each case elevation in BNP level occurred for a period exceeding 1 week. Although numbers were relatively small, a BNP >43 pmol/l was significantly associated with the inclusion of high-dose cyclophosphamide in the preparative regimen (P = 0.02). BNP levels showed no relationship to febrile episodes. In conclusion, these results show that plasma BNP may be used as a marker for early detection of cardiac dysfunction in patients undergoing HSCT, particularly if levels are increased for periods exceeding 1 week. Measurement of BNP during HSCT may be helpful in patients at risk of cardiac failure, in complex clinical situations and in monitoring the cardiotoxicity of preparative regimens.
    Full-text · Article · Aug 2000 · Bone Marrow Transplantation
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    ABSTRACT: We describe a man with relapsed large B cell mediastinal lymphoma and associated infected large anterior chest wall defect who required high dose salvage therapy for his underlying disease. An initial mediastinotomy wound, associated with recurrent sepsis, had developed into an abscess, then fistula and eventually a large anterior chest wall defect. Safe use of salvage chemotherapy required reconstructive surgery consisting of a pedicled muscle flap. The subsequent high dose chemotherapy was carried out without complications and 15 months later the patient is alive and well.
    No preview · Article · May 2000 · Clinical & Laboratory Haematology

  • No preview · Article · Apr 2000 · Gastroenterology

Publication Stats

5k Citations
455.42 Total Impact Points

Institutions

  • 2012
    • Sydney Orthopaedic Research Institute
      Sydney, New South Wales, Australia
  • 2001-2007
    • University of Queensland
      • Department of Medicine
      Brisbane, Queensland, Australia
    • Mater Hospital
      Brisbane, Queensland, Australia
  • 1999-2007
    • Mater Research
      South Brisbane, Queensland, Australia
  • 1998-2004
    • Mater Medical Research Institute
      South Brisbane, Queensland, Australia
  • 2003
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 1984-2001
    • Canterbury District Health Board
      • Department of Haematology
      Christchurch, Canterbury Region, New Zealand
  • 1997
    • University of Otago
      • Department of Medicine (Dunedin)
      Taieri, Otago Region, New Zealand