Professor Bruce Milthorpe joined UTS as Dean of Science in November 2008. Previously he was professor in the Graduate School of Biomedical Engineering, University of New South Wales. From February 2006 to August 2007, he was the Deputy President (Academic) of UNSW Asia.Prior to his time with UNSW Asia, he was Head of School of the Graduate School of Biomedical Engineering, UNSW, from 1998 until March 2006.
He has a background as a biochemist and biomaterials scientist with 20 years experience in biomaterials development and assessment, as well as interests in tissue engineering and cytometry. His research experience is in biomaterials, orthopaedic graft materials for reconstruction, hydroxyapatite ceramic composites, biomaterial interactions with bone, quantitative cytometry, polymer material interactions with proteins, and the use of cell culture and in vivo models for assessment of cellular and tissue interactions with materials. Recently he has been involved in developing an adult stem cell model in rabbits for bone and cartilage tissue engineering.
Professor Milthorpe has been an advisor to the Therapeutic Devices Evaluation Committee and the Therapeutic Goods Committee.
He is Chair of Culture at Work and a director of the Sydney Institute for Marine Science. He has been a member of the international editorial board of Biomaterials, and is now on the editorial board of two new journals in the field, as well as having served as an executive member of several research societies. He has published over 100 refereed journal articles and more than 120 conference presentations. Since 2000 he has been a chief investigator on biomedical research projects and grants with total funding in excess of $2.7 million. He has been named on three patents in the area of medical devices.
2009 - Member ARC LEIF Selection Advisory Committee
2009 - Member NHMRC Grant Review Panel (cell biology)
June 2009 - Member, International Editorial Board, Journal Materials Science: Materials in Medicine
June 2008 - Member, Editorial Board, International Journal of Biomaterials
2005 - EPSRC Peer Review College, UK.
1996 - 2001 Secretary, Scientific Advisory Committee, International Society for Analytical Cytology (ISAC)
1994 - 2004 Member, Scientific Advisory Committee, ISAC
1992 - 2005 Member, International Editorial Board of Biomaterials
1991 - 2003 Member, Executive Committee CRC for Eye Research and Technology
1999 - 2002 Member, Therapeutic Goods Committee, Australian Department of Health and Aged Care
Professional Society Memberships
1991 - Member, European Society for Biomaterials
1989 - Foundation Member, Australian Society for Biomaterials.
1986 - Member, International Society for Analytical Cytology
1978 - 2006 Foundation Member, Australasian Flow Cytometry Group.
1974 -1998 Member, Australian Society for Biochemistry and Molecular Biology
Sep 2013 - Director and Chair since 2014, Culture at Work
March 2014 - Director Sydney Institute for Marine Science
Sep 2009 - Jul 2014 Director, Insearch Ltd
Mar 2009 - 2014 Alternate Director, Sydney Institute for Marine Science
April 2002 - 2003 Member, Scientific Advisory Panel, Premier Bionics Ltd
2005 ICBME 2005 Honorary Award
2004 elected Fellow Biomaterials Science and Engineering
Can supervise: YES
My research interests are in the use and modification of materials as biomaterials and quantification of the biological response to these materials. These avenues have developed to include major areas such as:
- bioceramics including bioactive ceramics, biomaterials development, biomechanics of bone and reconstructions, image analysis in biomaterial testing, modification of cellular responses to biomaterials;
- biomaterials evaluation techniques
- biological molecule adsorption to surfaces; and
- tissue engineering, stem cells.
Biomaterials; Biomedical devices; Radiation Physics; Biomechanics, Tissue Engineering
Sayahi, M, Santos, J, El-Feki, H, Charvillat, C, Bosc, F, Karacan, I, Milthorpe, B & Drouet, C 2020, 'Brushite (Ca,M)HPO4, 2H2O doping with bioactive ions (M = Mg2+, Sr2+, Zn2+, Cu2+, and Ag+): a new path to functional biomaterials?', Materials Today Chemistry, vol. 16.View/Download from: Publisher's site
© 2019 Elsevier Ltd Dicalcium phosphate dihydrate, DCPD (CaHPO4·2H2O), brushite, is an important calcium phosphate compound encountered in mineralized tissues and used in medicine, especially in bone cement formulations. However, the use of DCPD as direct implantable biomaterial has not received dedicated attention. In addition, the possibility to dope DCPD with biologically active ions to modulate its performances was not systematically explored. We have investigated in depth the doping of DCPD with Mg2+, Sr2+, Zn2+, Cu2+, and Ag+ ions. Clear modifications in terms of chemical composition, particle size, pore distribution, crystal morphology, and affinity for water were pointed out. Then, the samples were cultured with human adipose-derived stem cells to explore cytotoxicity and proliferation. Various behaviors were noticed dependent on the incorporated metal ions. Such DCPD compounds associated with bioactive metal ions, and particularly Ag+ and Zn2+, appear promising as a new family of reactive materials for use, as such or in combination, in bone-related applications.
Dalla, PV, Santos, J, Milthorpe, BK & Padula, MP 2020, 'Selectively-packaged proteins in breast cancer extracellular vesicles involved in metastasis', International Journal of Molecular Sciences, vol. 21, no. 14, pp. 1-16.View/Download from: Publisher's site
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Cancer-derived extracellular vesicles are known to play a role in the progression of the disease. In this rapidly-growing field, there are many reports of phenotypic changes in cells following exposure to cancer-derived extracellular vesicles. This study examines the protein contents of vesicles derived from three well-known breast cancer cell lines, MCF-7, MDA-MB-231 and T47D, using peptide-centric LC-MS/MS and cytokine multiplex immunoassay analysis to understand the molecular basis of these changes. Through these techniques a large number of proteins within these vesicles were identified. A large proportion of these proteins are known to be important in cancer formation and progression and associated with cancer signaling, angiogenesis, metastasis and invasion and immune regulation. This highlights the importance of extracellular vesicles (EVs) in cancer communications and shows some of the mechanisms the vesicles use to assist in cancer progression.
Fajardo, J, Milthorpe, BK & Santos, J 2020, 'Molecular Mechanisms Involved in Neural Substructure Development during Phosphodiesterase Inhibitor Treatment of Mesenchymal Stem Cells.', International journal of molecular sciences, vol. 21, no. 14.View/Download from: Publisher's site
Stem cells are highly important in biology due to their unique innate ability to self-renew and differentiate into other specialised cells. In a neurological context, treating major injuries such as traumatic brain injury, spinal cord injury and stroke is a strong basis for research in this area. Mesenchymal stem cells (MSC) are a strong candidate because of their accessibility, compatibility if autologous, high yield and multipotency with a potential to generate neural cells. With the use of small-molecule chemicals, the neural induction of stem cells may occur within minutes or hours. Isobutylmethyl xanthine (IBMX) has been widely used in cocktails to induce neural differentiation. However, the key molecular mechanisms it instigates in the process are largely unknown. In this study we showed that IBMX-treated mesenchymal stem cells induced differentiation within 24 h with the unique expression of several key proteins such as Adapter protein crk, hypoxanthine-guanine phosphoribosyltransferase, DNA topoisomerase 2-beta and Cell division protein kinase 5 (CDK5), vital in linking signalling pathways. Furthermore, the increased expression of basic fibroblast growth factor in treated cells promotes phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MAPK) cascades and GTPase-Hras interactions. Bioinformatic and pathway analyses revealed upregulation in expression and an increase in the number of proteins with biological ontologies related to neural development and substructure formation. These findings enhance the understanding of the utility of IBMX in MSC neural differentiation and its involvement in neurite substructure development.
Santos, J, Hubert, T & Milthorpe, BK 2020, 'Valproic Acid Promotes Early Neural Differentiation in Adult Mesenchymal Stem Cells Through Protein Signalling Pathways.', Cells, vol. 9, no. 3.View/Download from: Publisher's site
Regenerative medicine is a rapidly expanding area in research and clinical applications. Therapies involving the use of small molecule chemicals aim to simplify the creation of specific drugs for clinical applications. Adult mesenchymal stem cells have recently shown the capacity to differentiate into several cell types applicable for regenerative medicine (specifically neural cells, using chemicals). Valproic acid was an ideal candidate due to its clinical stability. It has been implicated in the induction of neural differentiation; however, the mechanism and the downstream events were not known. In this study, we showed that using valproic acid on adult mesenchymal stem cells induced neural differentiation within 24 h by upregulating the expression of suppressor of cytokine signaling 5 (SOCS5) and Fibroblast growth factor 21 (FGF21), without increasing the potential death rate of the cells. Through this, the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway is downregulated, and the mitogen-activated protein kinase (MAPK) cascade is activated. The bioinformatics analyses revealed the expression of several neuro-specific proteins as well as a range of functional and structural proteins involved in the formation and development of the neural cells.
Santos, J, Milthorpe, BK & Padula, MP 2019, 'Correction: Santos, J., et al. Proteomic Analysis of Cyclic Ketamine Compounds Ability to Induce Neural Differentiation in Human Adult Mesenchymal Stem Cells. International Journal of Molecular Sciences 2019, 20, 523.', International journal of molecular sciences, vol. 20, no. 14.View/Download from: Publisher's site
The authors wish to make the following corrections to this paper [...].
Santos, J, Milthorpe, BK & Padula, MP 2019, 'Proteomic Analysis of Cyclic Ketamine Compounds Ability to Induce Neural Differentiation in Human Adult Mesenchymal Stem Cells.', International journal of molecular sciences, vol. 20, no. 3.View/Download from: Publisher's site
Neural regeneration is of great interest due to its potential to treat traumatic brain injuries and diseases that impact quality of life. Growth factor mediated differentiation can take up to several weeks to months to produce the cell of interest whereas chemical stimulation may be as minimal as a few hours. The smaller time scale is of great clinical relevance. Adipose derived stem cells (ADSCs) were treated for up to 24 h with a novel differentiation media containing the cyclic ketamine compounds to direct neurogenic induction. The extent of differentiation was investigated by proteome changes occurring during the process. The treatments indicated the ADSCs responded favorably to the neurogenic induction media by presenting a number of morphological cues of neuronal phenotype previously seen and a higher cell population post induction compared to previous studies. Furthermore, approximately 3500 proteins were analyzed and identified by mass spectrometric iTRAQ analyses. The bioinformatics analyses revealed hundreds of proteins whose expression level changes were statistically significant and biologically relevant to neurogenesis and annotated as being involved in neurogenic development. Complementing this, the Bioplex cytokine assay profiles present evidence of decreased panel of stress response cytokines and a relative increase in those involved in neurogenesis.
Chen, H, Ng, JPM, Bishop, DP, Milthorpe, BK & Valenzuela, SM 2018, 'Gold nanoparticles as cell regulators: beneficial effects of gold nanoparticles on the metabolic profile of mice with pre-existing obesity', JOURNAL OF NANOBIOTECHNOLOGY, vol. 16.View/Download from: Publisher's site
Green, DW, Ben-Nissan, B, Yoon, KS, Milthorpe, B & Jung, H-S 2017, 'Natural and Synthetic Coral Biomineralization for Human Bone Revitalization.', Trends in Biotechnology, vol. 35, no. 1, pp. 43-54.View/Download from: Publisher's site
Coral skeletons can regenerate replacement human bone in nonload-bearing excavated skeletal locations. A combination of multiscale, interconnected pores and channels and highly bioactive surface chemistry has established corals as an important alternative to using healthy host bone replacements. Here, we highlight how coral skeletal systems are being remolded into new calcified structures or synthetic corals by biomimetic processes, as places for the organized permeation of bone tissue cells and blood vessels. Progressive technologies in coral aquaculture and self-organization inorganic chemistry are helping to modify natural corals and create synthetic coral architectures able to accelerate bone regeneration with proper host integration at more skeletal locations, adapted to recent surgical techniques and used to treat intrinsic skeletal deformities and metabolic conditions.
Macha, IJ, Cazalbou, S, Shimmon, R, Ben-Nissan, B & Milthorpe, B 2017, 'Development and dissolution studies of bisphosphonate (clodronate)-containing hydroxyapatite-polylactic acid biocomposites for slow drug delivery.', Journal of Tissue Engineering and Regenerative Medicine, vol. 11, no. 6, pp. 1723-1731.View/Download from: Publisher's site
An increase in clinical demand on the controlled release of bisphosphonates (BPs) due to complications associated with systemic administration, has been the current driving force on the development of BP drug-release systems. Bisphosphonates have the ability to bind to divalent metal ions, such as Ca(2+) , in bone mineral and prevent bone resorption by influencing the apoptosis of osteoclasts. Localized delivery using biodegradable materials, such as polylactic acid (PLA) and hydroxyapatite (HAp), which are ideal in this approach, have been used in this study to investigate the dissolution of clodronate (non-nitrogen-containing bisphosphonate) in a new release system. The effects of coral structure-derived HAp and the release kinetics of the composites were evaluated. The release kinetics of clodronate from PLA-BP and PLA-HAp-BP systems seemed to follow the power law model described by Korsmeyer-Peppas. Drug release was quantified by (31) P-NMR with detection and quantification limits of 9.2 and 30.7 mM, respectively. The results suggest that these biocomposite systems could be tuned to release clodronate for both relatively short and prolonged period of time. In addition to drug delivery, the degradation of HAp supplies both Ca(2+) and phosphate ions that can help in bone mineralization. Copyright © 2015 John Wiley & Sons, Ltd.
Whyte, T, Gibson, T, Eager, D & Milthorpe, B 2017, 'Full-face motorcycle helmet protection from facial impacts: an investigation using THOR dummy impacts and SIMon finite element head model.', Injury Prevention, vol. 23, no. 3, pp. 205-210.View/Download from: Publisher's site
Facial impacts are both common and injurious for helmeted motorcyclists who crash; however, there is no facial impact requirement in major motorcycle helmet standards. This study examined the effect of full-face motorcycle helmet protection on brain injury risk in facial impacts using a test device with biofidelic head and neck motion. A preliminary investigation of energy absorbing foam in the helmet chin bar was carried out.Flat-faced rigid pendulum impacts were performed on a THOR dummy in an unprotected (no helmet) and protected mode (two full-face helmet conditions). The head responses of the dummy were input into the simulated injury monitor finite element head model to analyse the risk of brain injury in these impacts.Full-face helmet protection provides a significant reduction in brain injury risk in facial impacts at increasing impact speeds compared with an unprotected rider (p<0.05). The effect of low-density crushable foam added to the chin bar could not be distinguished from an unpadded chin bar impact.Despite the lack of an impact attenuation requirement for the face, full-face helmets do provide a reduction in head injury risk to the wearer in facial impacts. The specific helmet design factors that influence head injury risk in facial impacts need further investigation if improved protection for helmeted motorcyclists is to be achieved.
Santos, J, Milthorpe, BK, Herbert, BR & Padula, MP 2017, 'Proteomic Analysis of Human Adipose Derived Stem Cells during Small Molecule Chemical Stimulated Pre-neuronal Differentiation.', International journal of stem cells, vol. 10, no. 2, pp. 193-217.View/Download from: Publisher's site
Adipose derived stem cells (ADSCs) are acquired from abdominal liposuction yielding a thousand fold more stem cells per millilitre than those from bone marrow. A large research void exists as to whether ADSCs are capable of transdermal differentiation toward neuronal phenotypes. Previous studies have investigated the use of chemical cocktails with varying inconclusive results.Human ADSCs were treated with a chemical stimulant, beta-mercaptoethanol, to direct them toward a neuronal-like lineage within 24 hours. Quantitative proteomics using iTRAQ was then performed to ascertain protein abundance differences between ADSCs, beta-mercaptoethanol treated ADSCs and a glioblastoma cell line.The soluble proteome of ADSCs differentiated for 12 hours and 24 hours was significantly different from basal ADSCs and control cells, expressing a number of remodeling, neuroprotective and neuroproliferative proteins. However toward the later time point presented stress and shock related proteins were observed to be up regulated with a large down regulation of structural proteins. Cytokine profiles support a large cellular remodeling shift as well indicating cellular distress.The earlier time point indicates an initiation of differentiation. At the latter time point there is a vast loss of cell population during treatment. At 24 hours drastically decreased cytokine profiles and overexpression of stress proteins reveal that exposure to beta-mercaptoethanol beyond 24 hours may not be suitable for clinical application as our results indicate that the cells are in trauma whilst producing neuronal-like morphologies. The shorter treatment time is promising, indicating a reducing agent has fast acting potential to initiate neuronal differentiation of ADSCs.
Chou, J, Ito, T, Otsuka, M, Ben-Nissan, B & Milthorpe, B 2016, 'The effectiveness of the controlled release of simvastatin from β-TCP macrosphere in the treatment of OVX mice.', Journal of tissue engineering and regenerative medicine, vol. 10, no. 3, pp. E195-E203.View/Download from: Publisher's site
Simvastatin, a cholesterol treatment drug, has been shown to stimulate bone regeneration. As such, there has been an increase interest in the development of suitable materials and systems for the delivery of simvastatin. Without the appropriate dosage of simvastatin, the therapeutic effects on bone growth will be significantly reduced. Furthermore, similar to many pharmaceutical compounds, at high concentration simvastatin can cause various adverse side-effects. Given the associated side-effects with the usage of simvastatin, the development of suitable controlled drug release system is pertinent. Calcium phosphate in particularly beta-tricalcium phosphate (β-TCP) has been extensively studied and used as a carrier material for drug delivery system. In this study, Foraminifera exoskeletons were used as calcium carbonate precursor materials, which were hydrothermally converted to β-TCP as a carrier material for simvastatin. Natural marine exoskeletons posses interconnected and uniformly porous network capable of improving drug loading and release rate. To prolong the release of simvastatin, an apatite coating was made around the β-TCP sample and in vitro release studies in simulated body fluid (SBF) showed a significant decrease in release rate. Osteoporotic mice were used to examine the compare therapeutic effectiveness of β-TCP, β-TCP with simvastatin, apatite-coated β-TCP with simvastatin and direct injection of simvastatin near the right femur of the mice. Localized and systemic effect were compared with the femur of the non-implanted side (left) and showed that β-TCP with or without simvastatin was able to induce significant bone formation over 6 weeks. Mechanical analysis showed that apatite-coated β-TCP with simvastatin produced significantly stronger bones compared with other experimental groups. This study shows that natural exoskeletons with the appropriate structure can be successfully used as a drug delivery system for simvastatin and can its release ca...
Chou, J, Komuro, M, Hao, J, Kuroda, S, Hattori, Y, Ben-Nissan, B, Milthorpe, B & Otsuka, M 2016, 'Bioresorbable zinc hydroxyapatite guided bone regeneration membrane for bone regeneration', Clinical Oral Implants Research, vol. 27, no. 3, pp. 354-360.View/Download from: Publisher's site
Green, DW, Ben-Nissan, B, Yoon, K-S, Milthorpe, B & Jung, H-S 2016, 'Bioinspired materials for regenerative medicine: going beyond the human archetypes', JOURNAL OF MATERIALS CHEMISTRY B, vol. 4, no. 14, pp. 2396-2406.View/Download from: Publisher's site
Whyte, T, Gibson, T, Anderson, R, Eager, D & Milthorpe, B 2016, 'Mechanisms of Head and Neck Injuries Sustained by Helmeted Motorcyclists in Fatal Real-World Crashes: Analysis of 47 In-Depth Cases.', Journal of neurotrauma, vol. 33, no. 19, pp. 1802-1807.View/Download from: Publisher's site
Despite an improved understanding of traumatic head and neck injury mechanisms, the impact tests required by major motorcycle helmet standards have remained unchanged for decades. Development of new test methods must reflect the specific impact loads causing injury in real crashes as well as test criteria appropriate for the observed injury profiles. This study analysed a collection of in-depth crash investigations of fatally injured helmeted riders in the Adelaide metropolitan region between 1983 and 1994 inclusive to review the head and neck injury patterns that resulted from specific types of impact. Inertial brain injury was sustained in 49% of examined cases, most often resulting from facial impacts but also in a large proportion of tangential, run over, and occipital impact cases. Focal brain and brainstem injury was also common (53%) and regularly associated with skull vault (11/12) and skull base fractures (22/31). Prevention of these fractures in impacts outside the area of required protection and in impacts with a straight edge would provide a significant increase in helmeted rider protection. Cervical spinal cord injury was sustained in facial, straight edge, and tangential impacts on the head. Motorcycle helmets are effective for preventing local skull fractures in impacts for which they are designed, whereas other serious injuries such as basilar skull fracture (BSF) and inertial brain injury persist despite helmet protection. Further impact test procedures should be developed for injurious impact types not currently assessed by major helmet standards, in particular facial impacts, and using test criteria based on commonly observed injuries. This study provides the necessary link, from impact load to injury, for guiding impact test development.
Whyte, T, Gibson, T, Eager, D & Milthorpe, B 2016, 'Response of a full-face motorcycle helmet FE model to the UNECE 22.05 chin bar impact test', INTERNATIONAL JOURNAL OF CRASHWORTHINESS, vol. 21, no. 6, pp. 555-565.View/Download from: Publisher's site
Macha, IJ, Ben-Nissan, B, Santos, J, Cazalbou, S & Milthorpe, B 2016, 'Hydroxyapatite/PLA biocomposite thin films for slow drug delivery of antibiotics for the treatment of bone and implant-related infections', Key Engineering Materials, vol. 696, pp. 271-276.View/Download from: Publisher's site
© 2016 Trans Tech Publications, Switzerland. Drug delivery systems were developed from coralline hydroxyapatite (HAp) and biodegradable polylactic acid (PLA). Gentamicin (GM) was loaded in either directly to PLA (PLAGM) or in HAp microspheres. Drug loaded HAp was used to make thin film composites (PLAHApGM). Dissolution studies were carried out in phosphate buffered saline (PBS). The release profiles suggested that HAp particles improved drug stabilization and availability as well controlled the release rate. The release also displays a steady state release. In vitro studies in human Adipose Derived Stem Cells (hADSCs) showed substantial quantities of cells adhering to hydroxyapatite containing composites. The results suggested that the systems could be tailored to release different clinical active substances for a wide range of biomedical applications.
Chou, J, Hao, J, Hatoyama, H, Ben-Nissan, B, Milthorpe, B & Otsuka, M 2015, 'Effect of biomimetic zinc-containing tricalcium phosphate (ZnTCP) on the growth and osteogenic differentiation of mesenchymal stem cells', Journal of Tissue Engineering and Regenerative Medicine, vol. 9, no. 7, pp. 852-858.View/Download from: Publisher's site
Several studies have shown the effectiveness of zinc-tricalcium phosphate (Zn–TCP) for bone tissue engineering. In this study, marine calcareous foraminifera possessing uniform pore size distribution were hydrothermally converted to Zn–TCP. The ability of a scaffold to combine effectively with mesenchymal stem cells (MSCs) is a key tissue-engineering aim. In order to demonstrate the osteogenic ability of MSCs with Zn–TCP, the scaffolds were cultured in an osteogenic induction medium to elicit an osteoblastic response. The physicochemical properties of Zn–TCP were characterized by XRD, FT–IR and ICP–MS. MSCs were aspirated from rat femurs and cultured for 3 days before indirectly placing four samples into each respective well. After culture for 7, 10 and 14 days, osteoblastic differentiation was evaluated using alizarin red S stain, measurement of alkaline phosphatase (ALP) levels, cell numbers and cell viability. XRD and FT–IR patterns both showed the replacement of CO32– with PO43–. Chemical analysis showed zinc incorporation of 5 mol%. Significant increases in cell numbers were observed at 10 and 14 days in the Zn–TCP group, while maintaining high levels of cell viability (> 90%). ALP activity in the Zn–TCP group was statistically higher at 10 days. Alizarin red S staining also showed significantly higher levels of calcium mineralization in Zn–TCP compared with the control groups. This study showed that MSCs in the presence of biomimetically derived Zn–TCP can accelerate their differentiation to osteoblasts and could potentially be useful as a scaffold for bone tissue engineering.
Macha, IJ, Cazalbou, S, Ben-Nissan, B, Harvey, KL & Milthorpe, B 2015, 'Marine Structure Derived Calcium Phosphate-Polymer Biocomposites for Local Antibiotic Delivery', MARINE DRUGS, vol. 13, no. 1, pp. 666-680.View/Download from: Publisher's site
Chou, J, Hao, J, Kuroda, S, Ben-Nissan, B, Milthorpe, B & Otsuka, M 2014, 'Bone regeneration of calvarial defect using marine calcareous-derived beta-tricalcium phosphate macrosphere', Journal of Tissue Engineering, vol. 5, pp. 1-7.View/Download from: Publisher's site
The aim of this study was to examine the bone regeneration properties of beta-tricalcium phosphate hydrothermally converted from foraminifera carbonate exoskeleton in the repair of rat calvarial defect. These natural materials possess unique interconnected porous network with uniform pore size distribution, which can be potentially advantageous. In total, 20 adult male Wistar rats received full-thickness calvarial defect with a diameter of 5 mm. The rate of newly formed bone was measured radiologically by X-ray and micro-computed tomography and by histologic examination. After 2 weeks, the beta-tricalcium phosphate group exhibited full closure of the defect site, while control group remained unrestored at the end of the 6-week experimentation. It was observed that the newly regenerated bone thickened over the course of the experiment in the beta-tricalcium phosphate group. No soft tissue reaction was observed around the beta-tricalcium phosphate implant and the rats remained healthy. These results showed that repair of the calvarial defect can be achieved by biomimetic beta-tricalcium phosphate macrospheres, which hold potential for application as bone grafts for bone augmentation surgeries.
Lord, MS, Whitelock, JM, Simmons, A, Williams, RL & Milthorpe, BK 2014, 'Fibrinogen adsorption and platelet adhesion to silica surfaces with stochastic nanotopography', BIOINTERPHASES, vol. 9, no. 4.View/Download from: Publisher's site
Macha, IJ, Ben-Nissan, B & Milthorpe, B 2014, 'Improvement of Elongation in Nanosurface Modified Bioglass/PLA Thin Film Composites', Current Nanoscience, vol. 10, no. 2, pp. 200-204.View/Download from: Publisher's site
Chou, J, Valenzuela, S, Green, DW, Kohan, L, Milthorpe, B, Otsuka, M & Ben-Nissan, B 2014, 'Antibiotic delivery potential of nano and micro porous marine structures derived ß-TCP spheres for medical applications', Nanomedicine, vol. 1, pp. 1-9.View/Download from: Publisher's site
This study gives a detailed evaluation of the antibiotic potential of a marine structure-based new
drug delivery system produced by hydrothermally converting foraminifera exoskeletons to b-tricalcium
phosphate (b-TCP) to treat clinical strain Staphylococcus aureus (MW2). Materials & methods: Foraminifera
precursor materials were hydrothermally converted at 250°C for 48 h to produce b-TCP and loaded with
gentamicin sulfate by adsorption for 24 h. The physicochemical properties of the material were characterized
by scanning electron microscopy, powder x-ray diffraction and for pore size distribution profiles. The
antibacterial efficacy of the system was tested for inhibition of S. aureus growth and in vitro cellular
behavior were tested with human osteoblast cells (MG63) for cell viability. Discussion: Pore size distribution
profiles showed that the structure allows the uniform distribution of nanopores of 1.5 nm and micropores
of approximately 5 μm. The in vitro release profile indicates an initial burst release of 5% of total
incorporated gentamicin. A time-delayed antibacterial efficacy test was designed to introduce the bacteria
at predetermined time intervals from 0 to 60 min and showed that gentamicin prevents S. aureus grown
in the same culture within 30 min, with no evidence of bacterial regrowth within 24 h. Human osteoblast
cell (MG63) studies showed no detrimental effect on cell viability. Conclusion: In the light of these results
nano- and micro-pores
Chou, J, Valenzuela, SM, Santos, J, Bishop, D, Milthorpe, B, Green, DW, Otsuka, M & Ben-Nissan, B 2014, 'Strontium- and magnesium-enriched biomimetic beta-TCP macrospheres with potential for bone tissue morphogenesis', JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, vol. 8, no. 10, pp. 771-778.View/Download from: Publisher's site
Chou, J, Austin, C, Doble, P, Ben-Nissan, B & Milthorpe, B 2014, 'Trace elemental imaging of coralline hydroxyapatite by laser-ablation inductively coupled plasma-mass spectroscopy', JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, vol. 8, no. 7, pp. 515-520.View/Download from: Publisher's site
Chou, J, Green, DW, Singh, K, Hao, J, Ben-Nissan, B & Milthorpe, BK 2013, 'Adipose Stem Cell Coating of Biomimetic ß-TCP Macrospheres by Use of Laboratory Centrifuge', BioResearch Open Access, vol. 2, no. 1, pp. 67-71.View/Download from: Publisher's site
Biomimetic materials such as coral exoskeletons possess unique architectural structures with a uniform and interconnected porous network that can be beneficial as a scaffold material. In addition, these marine structures can be hydrothermally converted to calcium phosphates, while retaining the original structural properties. The ability of biomaterials to stimulate the local microenvironment is one of the main focuses in tissue engineering, and directly coating the scaffold with stem cells facilitates future potential applications in therapeutics and regenerative medicine. In this article we describe a new and simple method that uses a laboratory centrifuge to coat hydrothermally derived beta-tricalcium phosphate macrospheres from coral exoskeleton with stem cells. In this research the optimal seeding duration and speed were determined to be 1?min and 700 g. Scanning electron micrographs showed complete surface coverage by stem cells within 7 days of seeding. This study constitutes an important step toward achieving functional tissue-engineered implants by increasing our understanding of the influence of dynamic parameters on the efficiency and distribution of stem cell attachment to biomimetic materials and how stem cells interact with biomimetic materials.
Chou, J, Hao, J, Ben-Nissan, B, Milthorpe, BK & Otsuka, M 2013, 'Coral Exoskeletons as a Precursor Material for the Development of Calcium Phosphate Drug Delivery System for Bone Tissue Engineering', Biological & Pharmaceutical Bulletin, vol. 36, no. 11, pp. 1662-1665.View/Download from: Publisher's site
With the global rise in aging of populations, the occurrence of osteoporosis will continue to increase. Biomaterial and pharmaceutical scientists continue to develop innovative strategies and materials to address this disease. In this article, we describe a new perspective and approach into the use of coral exoskeletons as a precursor material to synthesize a calcium phosphate-based drug delivery system. Studies detailing the methodology of the conversion methods and the strategies and approach for the development of these novel drug delivery systems are described. Furthermore, in vivo studies in osteoporotic mice using a drug loaded and chemically modified version of the biomimetic delivery system showed significant cortical and cancellous bone increases. These studies support the notion and the rationale for future research and development of the use of coral exoskeletons as materials for drug delivery applications
Chou, J, Hao, J, Hatoyama, H, Ben-Nissan, B, Milthorpe, BK & Otsuka, M 2013, 'The therapeutic effect on bone mineral formation from biomimetic zinc containing tricalcium phosphate (ZnTCP) in zinc-deficient osteoporotic mice', PLoS One, vol. 8, no. 8, pp. e71821-e71821.View/Download from: Publisher's site
The aim of this study was to evaluate the therapeutic efficacy of biomimetic zinc-containing tricalcium phosphate (ZnTCP) produced by hydrothermally converting calcium carbonate exoskeletons from foraminifera, in the treatment of osteoporotic mice. X-Ray powder diffraction showed crystallographic structures matching JCPDS profile for tricalcium phosphate. Mass spectroscopy used to calculate total composition amount showed similar amount of calcium (5×104 µg/g) and phosphate (4×104 ppm) after conversion and the presence of zinc (5.18×103 µg/g). In vitro zinc release showed no release in PBS buffer and <1% zinc release in 7 days. In vivo evaluation was done in ovariectomized mice by implanting the ZnTCP samples in the soft tissues near the right femur bone for four weeks. Thirty ddY mice (5 weeks old, average weight of 21 g) were divided into six experimental groups (normal, sham, OVX, ß-TCP, ZnTCP and direct injection of zinc). CT images were taken every two weeks where the bone mineral density (BMD) and bone mineral content (BMC) were calculated by software based on CT images. The ZnTCP group exhibits cortical and cancellous bone growth of 45% and 20% respectively. While sham, OVX and ß-TCP suffered from bone loss. A correlation was made between the significant body weight increase in ZnTCP with the significant increase in plasma zinc level compared with OVX. The presented results indicate that biomimetic ZnTCP were effective in preventing and treating bone loss in osteoporotic mice model.
Chou, J, Ito, T, Otsuka, M, Ben-Nissan, B & Milthorpe, BK 2013, 'Simvastatin-loaded Beta-tCP Drug Delivery System Induces Bone Formation And Prevents Rhabdomyolysis In OVX Mice', Advanced Healthcare Materials, vol. 2, no. 5, pp. 678-681.View/Download from: Publisher's site
Bone formation and regeneration is a prolonged process that requires a slow drug release system to assist in the long-term recovery. A drug-delivery system is developed that allows for the controlled release of simvastin, without exhibiting the side effects associated with high concentrations of simvastatin, and is still capable of inducing constant bone formation.
Chou, J, Ito, T, Otsuka, M, Ben-Nissan, B & Milthorpe, BK 2013, 'The Controlled Release Of Simvastatin From Biomimetic Macrospheres', Key Engineering Materials, vol. 529-530, pp. 461-464.View/Download from: Publisher's site
Simvastatin has been shown to succesfully stimulate bone regeneration and attention has being focussed on developing appropriate delivery carriers for its release. The challenge of deliverying therapeutic concentration of pharmaceutical compunds has bein
Chou, J, Hao, J, Kuroda, S, Bishop, DP, Ben-Nissan, B, Milthorpe, BK & Otsuka, M 2013, 'Bone regeneration of rat tibial defect by zinc-tricalcium phosphate (Zn-TCP) from porous Foraminifera carbonate macrospheres', Marine Drugs, vol. 11, no. 12, pp. 5148-5158.View/Download from: Publisher's site
Foraminifera carbonate exoskeleton was hydrothermally converted to biocompatible and biodegradable zinc-tricalcium phosphate (Zn-TCP) as an alternative biomimetic material for bone fracture repair. Zn-TCP samples implanted in a rat tibial defect model for eight weeks were compared with unfilled defect and beta-tricalcium phosphate showing accelerated bone regeneration compared with the control groups, with statistically significant bone mineral density and bone mineral content growth. CT images of the defect showed restoration of cancellous bone in Zn-TCP and only minimal growth in control group. Histological slices reveal bone in-growth within the pores and porous chamber of the material detailing good bone-material integration with the presence of blood vessels. These results exhibit the future potential of biomimetic Zn-TCP as bone grafts for bone fracture repair.
Chou, J, Ito, T, Bishop, D, Otsuka, M, Ben-Nissan, B & Milthorpe, B 2013, 'Controlled release of simvastatin from biomimetic β-TCP drug delivery system.', PLoS ONE, vol. 8, no. 1, pp. 1-6.View/Download from: Publisher's site
Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin.
Cortie, MB, Al Hafed, E, Chen, H, Valenzuela, S, Ting, S, Sonvico, F & Milthorpe, BK 2013, 'Nanomedical research in Australia and New Zealand', Nanomedicine, vol. 8, no. 12, pp. 1999-2006.View/Download from: Publisher's site
Although Australia and New Zealand have a combined population of less than 30 million, they have an active and interlinked community of nanomedical researchers. This report provides a synopsis and update on this network with a view to identifying the main topics of interest and their likely future trajectories. In addition, our report may also serve to alert others to opportunities for joint projects. Australian and New Zealand researchers are engaged in most of the possible nanomedical topics, but the majority of interest is focused on drug and nucleic acid delivery using nanoparticles or nanoporous constructs. There are, however, smaller programs directed at hyperthermal therapy and radiotherapy, various kinds of diagnostic tests and regenerative technologies.
Green, DW, Padula, M, Santos, J, Chou, J, Milthorpe, BK & Ben-Nissan, B 2013, 'A Therapeutic Potential for Marine Skeletal Proteins in Bone Regeneration.', Marine Drugs, vol. 11, no. 4, pp. 1203-1220.View/Download from: Publisher's site
A vital ingredient for engineering bone tissue, in the culture dish, is the use of recombinant matrix and growth proteins to help accelerate the growth of cultivated tissues into clinically acceptable quantities. The skeletal organic matrices of calcifying marine invertebrates are an untouched potential source of such growth inducing proteins. They have the advantage of being ready-made and retain the native state of the original protein. Striking evidence shows that skeleton building bone morphogenic protein-2/4 (BMP) and transforming growth factor beta (TGF-ß) exist within various marine invertebrates such as, corals. Best practice mariculture and the latest innovations in long-term marine invertebrate cell cultivation can be implemented to ensure that these proteins are produced sustainably and supplied continuously. This also guarantees that coral reef habitats are not damaged during the collection of specimens. Potential proteins for bone repair, either extracted from the skeleton or derived from cultivated tissues, can be identified, evaluated and retrieved using chromatography, cell assays and proteomic methods. Due to the current evidence for bone matrix protein analogues in marine invertebrates, together with the methods established for their production and retrieval there is a genuine prospect that they can be used to regenerate living bone for potential clinical use.
Stem cells can become potent tools for the treatment of degenerative disorders such as heart failure, eye disease and osteoarthritis. Housing stem cells inside a hydrogel coating, directly deposited around them individually and in groups, may be an important solution to the problem of increasing stem cell viability and protection in cultivation. Such coatings can target regulatory proteins and genes for maintenance, differentiation and development into tissues. Already polymer coatings are being applied directly to protect insulin producing pancreatic islet cells in the hope of treating type I diabetes. Here, we review current emerging developments in adult mesenchymal stem cell nanocoating and microcoating techniques and assess their unique practical engineering, biological and potential clinical advantages.
Langtry, T, Giokaris, P, Milthorpe, B & Lord, ME 2012, 'Parameter estimation for a model of fibronectin adsorption onto hydroxylapatite, oxidised polystyrene and nanostructured silica', ANZIAM Journal : Electronic Supplement, vol. 54, pp. c429-c445.View/Download from: Publisher's site
Fibronectin is a protein present in blood and the extracellular matrix which has important roles in cell adhesion and migration, wound healing and blood clotting. Three models of fibronectin adsorption, on various substrates of interest to biochemists, are compared. The first model (of Langmuir) is expressed explicitly as a time dependent function for the mass of protein adsorbed. The second model is a modification of the scaled particle theory of Reiss et al. [J. Chem. Phys., 31:369--380, 1959] and takes into account the probability of a molecule finding a sufficiently large vacant area on the adsorbing substrate surface. The third model extends the second model to the case in which molecules may expand the radius of their contact with the substrate upon adsorption. We used datasets obtained from experiments to compare the models. The Langmuir model is straightforward to fit to a dataset. The remaining models are fitted using a steepest descent method to minimise least squares error. We describe initial estimates for parameters for this procedure and compare the quality of fit of the models
Jones, AC, Arns, CH, Hutmacher, DW, Milthorpe, BK, Sheppard, AP & Knackstedt, M 2009, 'The correlation of pore morphology, interconnectivity and physical properties of 3D ceramic scaffolds with bone ingrowth', Biomaterials, vol. 30, no. 7, pp. 1440-1451.View/Download from: Publisher's site
In the design of tissue engineering scaffolds, design parameters including pore size, shape and interconnectivity, mechanical properties and transport properties should be optimized to maximize successful inducement of bone ingrowth. In this paper we describe a 3D micro-CT and pore partitioning study to derive pore scale parameters including pore radius distribution, accessible radius, throat radius, and connectivity over the pore space of the tissue engineered constructs. These pore scale descriptors are correlated to bone ingrowth into the scaffolds. Quantitative and visual comparisons show a strong correlation between the local accessible pore radius and bone ingrowth; for well connected samples a cutoff accessible pore radius of similar to 100 mu M is observed for ingrowth. The elastic properties of different types of scaffolds are simulated and can be described by standard cellular solids theory: (E/E(0))-(rho/rho(s))(n). Hydraulic conductance and diffusive properties are calculated; results are consistent with the concept of a threshold conductance for bone ingrowth. Simple simulations of local flow velocity and local shear stress show no correlation to in vivo bone ingrowth patterns. These results demonstrate a potential for 3D imaging and analysis to define relevant pore scale morphological and physical properties within scaffolds and to provide evidence for correlations between pore scale descriptors, physical properties and bone ingrowth.
Lord, MS, Pasqui, D, Barbucci, R & Milthorpe, BK 2009, 'Protein adsorption on derivatives of hyaluronic acid and subsequent cellular response', Journal of Biomedical Materials Research Part A, vol. 91A, no. 3, pp. 635-646.View/Download from: Publisher's site
The modulation of biological interactions with artificial surfaces is a vital aspect of biomaterials research. Serum protein adsorption onto photoreactive hyaluronic acid (Hyal-N3) and its sulfated derivative (HyalS-N3) was analyzed to determine extent of protein interaction and protein conformation as well as subsequent cell adhesion. There were no significant (p < 0.01) differences in the amount of protein adsorbed to the two polymers; however, proteins were found to be more loosely bound on HyalS-N3 compared with Hyal-N3. Fibronectin was adsorbed onto HyalS-N3 in such an orientation as to allow the availability of the cell binding region, while there was more restricted access to this region on fibronectin adsorbed onto Hyal-N3. This was confirmed by reduced cell adhesion on fibronectin precoated Hyal-N3 compared with fibronectin precoated HyalS-N3. Minimal cell adhesion was observed on albumin and serum precoated Hyal-N3. The quartz crystal microbalance confirmed that specific cell-surface interactions were experienced by cells interacting with the fibronectin precoated polymers and serum precoated HyalS-N3
Milthorpe, BK 2009, 'In Vitro Adsorption of Tear Proteins to Hydroxyethyl Methacrylate-Based Contact Lens Materials', Eye and Contact Lens: Science and Clinical Practice, vol. 35, no. 6, pp. 320-328.View/Download from: Publisher's site
Investigations of polymer interactions in single protein solutions is a necessary step in the elucidation of in vivo early binding events during protein deposition on hydroxyethyl methacrylate-based contact lens materials. Quantity and tenacity of binding of significant tear components to groups I and IV contact lenses was assessed. Competitive binding by these components was also examined. METHODS: Adsorption on FDA groups I and IV hydrogel lenses was monitored using I-labeled protein. Lenses were incubated in increasing concentrations of radiolabeled single species proteins in solution. For competition experiments, concentration of each radiolabeled protein was held constant and the adsorption/sorption challenged with increasing concentrations of nonlabeled proteins. Lenses were soaked in phosphate-buffered saline to determine desorption. RESULTS: Group IV lenses bound large amounts of lysozyme, whereas group I lenses bound highest amounts of albumin. Albumin binding to both lens types was relatively strong and could not be competed from binding by other proteins lysozyme, lactoferrin, and mucin. Mucin at high concentrations tended to positively cooperate with the binding of lactoferrin and albumin to all lenses. CONCLUSIONS: Binding of proteins to hydroxyethyl methacrylate-based hydrogel lens surfaces is affected by charge and polymer components, and perhaps manufacturing processes. Albumin binds strongly to lens surfaces, and this may play an adverse role during contact lens wear.
Lord, MS, Modin, C, Foss, M, Duch, M, Simmons, A, Pedersen, FS, Besenbacher, F & Milthorpe, BK 2008, 'Extracellular matrix remodelling during cell adhesion as monitored by the quartz crystal microbalance', Biomaterials, vol. 29, no. 17, pp. 2581-2587.View/Download from: Publisher's site
A cell's ability to remodel adsorbed protein layers on surfaces is influenced by the nature of the protein layer itself. Remodelling is often required to accomplish cellular adhesion and extracellular matrix formation which forms the basis for cell spreading, increased adhesion and expression of different phenotypes. The adhesion of NIH3T3 (EGFP) fibroblasts to serum protein (albumin or fibronectin) precoated tantalum (Ta) and oxidised polystyrene (PSox) surfaces was examined using the quartz crystal microbalance with dissipation (QCM-D) monitoring and fluorescence microscopy. The cells were either untreated or treated with cycloheximide to examine the contribution of endogenous protein production during cell adhesion to the QCM-D response over a period of 2 h. Following adsorption of albumin onto Ta and PSox there was no difference detected between the response to seeding untreated and cycloheximide treated cells. The QCM-D was able to detect differences in the untreated cellular responses to fibronectin versus serum precoated Ta and PSox substrates, while cycloheximide treatment of the cells produced the same QCM-D response for fibronectin and serum precoatings on each of the materials. This confirmed that the process of matrix remodelling by the cells is dependent on the underlying substrate and the preadsorbed proteins and that the QCM-D response is dominated by changes in the underlying protein layer. Changes in dissipation correspond to the development of the actin cytoskeleton as visualised by actin staining.
Serum protein adsorption and fibroblast cell adhesion on photo reactive hyaluronic acid (Hyal-N3) and its sulfated derivative (HyalS-N3) was analysed using a combination of quartz crystal microbalance (QCM) and cell adhesion assays. There was no significant differences in the amount of protein adsorbed onto the two polymers, however proteins were found to be more loosely bound to HyalS-N3 compared with Hyal-N3. Approximately 17% and 31% of the fibronectin interacting with Hyal-N3 and HyalS-N3 respectively was found to be irreversibly bound after rinsing with MilliQ water, SDS and urea. Proteins were exposed to the polymers before cell adhesion was monitored for a period of 2 hours in serum free conditions. Minimal cell adhesion was observed on albumin-coated materials as well as serum precoated Hyal-N3. Precoating the materials with fibronectin enhanced cell adhesion, although HyalS-N3 experienced higher levels of cell adhesion than Hyal-N3 and similar results were found for the serum precoated materials.
Cellular biomechanics is an area of study that is receiving more attention as time progresses. The response of cells to their mechanical environment, including biomechanical stimuli, has far-reaching ramifications for the area of tissue engineering, especially for tissues designed to withstand mechanical loading (e.g. bone, cartilage, tendons and ligaments, and arteries). The effects of mechanical stimuli on cells are only recently being examined, and the potential role of mechanical stimuli in tissue engineering is still one that is largely ignored in the design of tissue engineering scaffolds. The relationship of mechanical properties of scaffolds or of mechanical stimuli to cell behavior is complex, but vital to the development of the field. Also, understanding the complex interplay of form and environment on cells involves an increase in our knowledge of how cells react to their total environment including mechanical stimuli and material properties. In order to improve tissue engineering outcomes, a nexus must be developed between the mechanical, biochemical, and biological studies of cellular behavior, in the context of extremely complex systems
Jones, AC, Arns, CH, Sheppard, AP, Hutmacher, DW, Milthorpe, BK & Knackstedt, M 2007, 'Assessment of bone ingrowth into porous biomaterials using MICRO-CT', Biomaterials, vol. 28, no. 15, pp. 2491-2504.View/Download from: Publisher's site
The three-dimensional (3D) structure and architecture of biomaterial scaffolds play a critical role in bone formation as they affect the functionality of the tissue-engineered constructs. Assessment techniques for scaffold design and their efficacy in bone ingrowth studies require an ability to accurately quantify the 3D structure of the scaffold and an ability to visualize the bone regenerative processes within the scaffold structure. In this paper, a 3D micro-CT imaging and analysis study of bone ingrowth into tissue-engineered scaffold materials is described. Seven specimens are studied in this paper; a set of three specimens with a cellular structure, varying pore size and implant material, and a set of four scaffolds with two different scaffold designs investigated at early (4 weeks) and late (12 weeks) explantation times. The difficulty in accurately phase separating the multiple phases within a scaffold undergoing bone regeneration is first highlighted. A sophisticated three-phase segmentation approach is implemented to develop high-quality phase separation with minimal artifacts. A number of structural characteristics and bone ingrowth characteristics of the scaffolds are quantitatively measured on the phase separated images. Porosity, pore size distributions, pore constriction sizes, and pore topology are measured on the original pore phase of the scaffold volumes. The distribution of bone ingrowth into the scaffold pore volume is also measured. For early explanted specimens we observe that bone ingrowth occurs primarily at the periphery of the scaffold with a constant decrease in bone mineralization into the scaffold volume.
Ko, H, Milthorpe, BK & McFarland, CD 2007, 'Engineering thick tissues - the vascularisation problem - Discussion with reviewers', EUROPEAN CELLS & MATERIALS, vol. 14, pp. 18-19.
Ko, HC, Milthorpe, BK & McFarland, CD 2007, 'Engineering thick tissues - the vascularisation problem', European Cells and Materials, vol. 14, no. 1, pp. 1-19.
The ability to create thick tissues is a major tissue engineering challenge, requiring the development of a suitable vascular supply. Current trends are seeing the utilization of cells seeded into hybrid matrix/scaffold systems to create in vitro vascular analogues. Approaches that aim to create vasculature in vitro include the use of biological extracellular matrices such as collagen hydrogels, porous biodegradable polymeric scaffolds with macro- and micro-lumens and micro-channels, co-culture of cells, incorporation of growth factors, culture in dynamic bioreactor environments, and combinations of these. Of particular interest are those approaches that aim to create bioengineered tissues in vitro that can be readily connected to the host's vasculature following implantation in order to maintain cell viability.
Hitchcock, R, Sears, W, Gillies, RM, Milthorpe, BK & Walsh, WR 2006, 'In vitro study of shear force on interbody implants', Journal of Spinal Disorders & Techniques, vol. 19, no. 1, pp. 32-36.
The lordosis of the lumbar spine and body weight result in significant shear forces through the lumbosacral elise spaces. These forces result in translational motion across the disc space, which is resisted but not completely abolished by pedicle screw stabilization. It is postulated that this motion may be a factor in the development of nonunion of lumbar interbody fusions. An in vitro study of the micromotion of porcine specimens with serrated or smooth interbody spacers and subjected to shear forces under compressive preload was conducted to determinewhether the surface serrations on vertebral interbody implants significantly resist shear forces and resulting sagittal translation.
Lord, MS, Cousins, BG, Doherty, PJ, Whitelock, JM, Simmons, A, Williams, RL & Milthorpe, BK 2006, 'The effect of silica nanoparticulate coatings on serum protein adsorption and cellular response', Biomaterials, vol. 27, no. 28, pp. 4856-4862.View/Download from: Publisher's site
Serum protein adsorption on colloidal silica surfaces was investigated using a quartz crystal microbalance with dissipation (QCM-D) monitoring. The amount of serum proteins adsorbed on colloidal silica-coated surfaces was not significantly different from the control silica surfaces, with the exception of 21 nm colloidal silica which experienced significantly less (P<0.05) fibrinogen adsorption compared with control silica. The adhesion and proliferation of human endothelial cells (C11STH) on nano-scale colloidal silica surfaces were significantly reduced compared with control silica surfaces, suggesting that the conformation of adsorbed proteins on the colloidal silica surfaces plays a role in modulating the amount of cell binding. Fibronectin is one of the main extracellular matrix proteins involved in endothelial cell attachment to biomaterial surfaces. There was reduced binding of a monoclonal anti-fibronectin antibody, that reacted specifically with the cell-binding fragment, to fibronectin-coated colloidal silica surfaces compared with control silica surfaces. This suggests that the fibronectin adsorbed on the colloidal silica-coated surfaces was conformationally changed compared with control silica reducing the availability of the cell-binding domain of fibronectin.
Lord, MS, Modin, C, Foss, M, Duch, M, Simmons, A, Pedersen, FS, Milthorpe, BK & Besenbacher, F 2006, 'Monitoring cell adhesion on tantalum and oxidised polystyrene using a quartz crystal microbalance with dissipation', Biomaterials, vol. 27, no. 26, pp. 4529-4537.View/Download from: Publisher's site
The quartz crystal microbalance with dissipation (QCM-D) (Q-Sense AB, Sweden) has been established as a useful tool for evaluating interactions between various biological and non-biological systems, and there has been increasing interest in using the QCM-D technique for cell monitoring applications. This study investigated the potential of the QCM-D to characterise the initial adhesion and spreading of cells in contact with protein precoated biocompatible surfaces. The QCM-D technique is attractive for monitoring cell adhesion and spreading as it allows in situ real-time measurements. The adhesion of NIH3T3 (EGFP) fibroblasts to tantalum (Ta) and oxidised polystyrene (PSox) surfaces precoated with serum proteins was examined using the QCM-D for a period of either 2 or 4 h. Time-lapse photography was performed at 30 min intervals to visually examine cell adhesion and spreading in order to relate cell morphology to the QCM-D response.
Lysozyme interaction with an acrylic-based hydrogel, poly(2-hydroxyethyl methacrylate) co-methacrylic acid (P(HEMA-MAA)), was investigated using a combination of quartz crystal microbalance with dissipation (QCM-D), surface plasmon resonance (SPR) and dual polarisation interferometry (DPI). This combination of techniques demonstrated that lysozyme initially absorbed into the hydrogel matrix and displaced water from the hydrogel while subsequent lysozyme additions were adsorbed onto the surface of the hydrogel material. QCM-D, being sensitive to bound water, showed an overall decrease in mass and stiffening of the layer after lysozyme addition. SPR, a water insensitive technique, showed a net mass increase after addition of lysozyme and buffer rinses. DPI showed that the first exposure of lysozyme to P(HEMA-MAA) was consistent with lysozyme absorption while subsequent lysozyme exposures were consistent with lysozyme adsorption.
Lord, MS, Stenzel, M, Simmons, A & Milthorpe, BK 2006, 'The effect of charged groups on protein interactions with poly(HEMA) hydrogels', Biomaterials, vol. 27, no. 4, pp. 567-575.View/Download from: Publisher's site
Proteins, lipids and other biomolecules interact strongly with the acrylic-based biomaterials used for contact lenses. Although hydrogels are nominally resistant to protein fouling, many studies have reported considerable amounts of protein bound to poly(2-hydroxyethylmethacrylate) (PHEMA) lenses. This study examined the binding of a series of biomolecules (tear protein analogues, mucin and cholesterol) to poly(methylmethacrylate) (PMMA) and three HEMA-based hydrogels (PHEMA, HEMA plus methacrylic acid (P(HEMAMAA)), HEMA plus methacrylic acid plus N-vinylpyrrolidone (P(HEMAMAANVP))) by use of a quartz crystal microbalance with dissipation (QCM-D) monitoring. The QCM-D estimates changes in the mass and viscous constant for the adsorbed layer through measurements of frequency and dissipation.
Lord, MS, Stenzel, MH, Simmons, A & Milthorpe, BK 2006, 'The effect of charged groups on protein interactions with poly(HEMA) hydrogels', BIOMATERIALS, vol. 27, no. 4, pp. 567-575.View/Download from: Publisher's site
Marcal, H, Raftery, M, Sarris, M, Mcfarland, C, Milthorpe, BK, Bhasin, V, Mackay-Sim, A & Mahler, S 2006, 'Secretome analysis of olfactory ensheathing cells for use in tissue engineering and regenerative medicine applications', MOLECULAR & CELLULAR PROTEOMICS, vol. 5, no. 10, pp. S92-S92.
Nordon, RE, Godora, P, Ko, K, Milthorpe, BK & McFarland, CD 2006, 'Identification of adult stem cells for tissue engineering applications', Cytometry, vol. 69A, no. 5, pp. 417-417.
Wei, M, Ruys, AJ, Milthorpe, BK & Sorrell, CC 2005, 'Precipitation of hydroxyapatite nanoparticles: Effects of precipitation method on electrophoretic deposition', Journal Of Materials Science-materials In Medicine, vol. 16, pp. 319-324.View/Download from: Publisher's site
Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite ( HA) coatings on metal implants with a broad range of thicknesses, from < 1 mu m to > 500 mu m. As for many other HA coating techniques, densification of electrophoretically deposited coatings involves heating the coated metal to temperatures above 1000 degrees C. Metal substrates tend to react with HA coatings at such temperatures inducing decomposition at temperatures below 1050 degrees C ( decomposition for pure HA normally occurs above 1300 degrees C). Therefore, densification of these coatings needs to be conducted at temperatures lower than 1050 degrees C, and this necessitates the use of high-surface-area HA nano-precipitates, rather than commercially available pre-calcined powders, which densify at temperatures typically higher than 1200 degrees C. HA nano-precipitates were prepared by three methods and deposited on metal substrates by electrophoresis: ( 1) the acid base method, which produced plate-like nano-particles with a 2.5: 1 aspect ratio, and severely cracked coatings; ( 2) the calcium acetate method, which produced needle-like nano-particles with a 10: 1 aspect ratio, and slightly cracked coatings; ( 3) the metathesis method, which produced rounded nano-particles with a 2: 1 aspect ratio, and high-quality crack-free coatings. The results suggested that the less equiaxed the nano-particles, the more cracked the coatings obtained by the electrophoretic deposition technique
Wei, M, Ruys, AJ, Swain, MV, Milthorpe, BK & Sorrell, CC 2005, 'Hydroxyapatite-coated metals: Interfacial reactions during sintering', Journal Of Materials Science-materials In Medicine, vol. 16, pp. 101-106.
Electrophoretic deposition (EPD) is a low cost flexible process for producing HA coatings on metal implants. Its main limitation is that it requires heating the coated implant in order to densify the HA. HA typically sinters at a temperature below 1150 degreesC, but metal implants are degraded above 1000 degreesC. Further, the metal induces the decomposition of the HA coating upon sintering. Recent developments have enabled EPD of metathesis-synthesised uncalcined HA which sinters at similar to 1000 degreesC. The effects of temperature on HA-coated Ti, T16AI4V, and 316L stainless steel were investigated for dual coatings of metathesis HA sintered at 1000 degreesC. The use of dual HA coatings (coat, sinter, coat, sinter) enabled decomposition to be confined to the "undercoat" (HA layer 1), with the surface coating decomposition free. The tensile strength of the three metals was not significantly affected by the high sintering temperatures (925 degreesC < T < 1000degreesC). XRD/SEM/EDS analyses of the interfacial zones revealed that 316L had a negligible HA:metal interfacial zone (similar to1 mum) while HA:Ti and HA:Ti6Al4V had large interfacial zones (>10 mum) comprising a TiO2 oxidation zone and a CaTiO3 reaction zone
Fornusek, C, Davis, GM, Sinclair, P & Milthorpe, BK 2004, 'Development of an Isokinetic Functional Electrical Stimulation Cycle Ergometer', Neuromodulation, vol. 7, no. 1, pp. 56-64.View/Download from: Publisher's site
An isokinetic functional electrical stimulation leg cycle ergometer (iFES-LCE) was developed for individuals with spinal cord injury (SCI). The iFES-LCE was designed to allow cycle training over a broad range of pedalling cadences (560 rev/min) to promote both muscular strength and cardiorespiratory fitness. A commercially available motorized cycle ergometer was integrated with a custom built FES system, a laptop computer, and a specialized chair that restricted lateral leg movements. Sample biomechanical data were collected from an SCI subject performing FES cycling to demonstrate the iFES-LCE's performance characteristics. Calibration of the iFES-LCE system revealed a linear relationship between torque applied to the axle of the motorized ergometer and the braking motor current generated to maintain velocity. Performance data derived from iFES-LCE motor torque agreed closely with similar data collected using strain-gauge instrumented pedals (cross-correlations = 0.930.98). The iFES-LCE was shown to work well across a range of pedaling cadences. We conclude that the new iFES-LCE system may offer improved training potential by allowing cycling over a broad range of pedaling cadences, especially low cadence. This device also improves upon the accuracy of other ergometers by adjusting for the passive load of the legs.
Jones, AC, Milthorpe, BK, Averdunk, H, Limaye, A, Senden, TJ, Sakellariou, A, Sheppard, AP, Sok, RM, Knackstedt, M, Brandwood, A, Rohner, D & Hutmacher, DW 2004, 'Analysis of 3D bone ingrowth into polymer scaffolds via micro-computed tomography imaging', Biomaterials, vol. 25, no. 20, pp. 4947-4954.View/Download from: Publisher's site
This paper illustrates the utility of micro-computed tomography (micro-CT) to study the process of tissue engineered bone growth. A micro-CT facility for imaging and visualising biomaterials in three dimensions (3D) is described. The facility is capable of acquiring 3D images made up of 20003 voxels on specimens up to 60 mm in extent with resolutions down to 2 ?m. This allows the 3D structure of tissue engineered materials to be imaged across three orders of magnitude of detail. The capabilities of micro-CT are demonstrated by imaging the Haversian network within human femoral cortical bone (distal diaphysis) and bone ingrowth into a porous scaffold at varying resolutions. Phase identification combined with 3D visualisation enables one to observe the complex topology of the canalicular system of the cortical bone. Imaging of the tissue engineered bone at a scale of 1 cm and resolutions of 10 ?m allows visualisation of the complex ingrowth of bone into the polymer scaffold. Further imaging at 2 ?m resolution allows observation of bone ultra-structure. These observations illustrate the benefits of tomography over traditional techniques for the characterisation of bone morphology and interconnectivity and performs a complimentary role to current histomorphometric techniques.
Jones, AC, Sakellariou, A, Limaye, A, Arns, CH, Senden, TJ, Sawkins, T, Knackstedt, M, Rohner, D, Hutmacher, DW, Brandwood, A & Milthorpe, BK 2004, 'Investigation ogf microstructural features in regenerating bone using micro computed tomography', Journal Of Materials Science-materials In Medicine, vol. 15, pp. 529-532.View/Download from: Publisher's site
Jones, AC, Sheppard, AP, Sok, RM, Arns, CH, Limaye, A, Averdunk, H, Brandwood, A, Sakellariou, A, Senden, TJ, Milthorpe, BK & Knackstedt, M 2004, 'Three-dimensional analysis of cortical bone structure using X-ray micro-computed tomography', Physica A: Statistical Mechanics and its Applications, vol. 339, no. 1-2, pp. 125-130.View/Download from: Publisher's site
We demonstrate the capability of X-ray micro-computed tomography to image the micro-structure of human cortical bone. At 5 ?m voxel size we observe the complex morphology of the Haversian network in three dimensions. The local thickness of Haversian canals is measured using a maximal sphere algorithm and found to have a bimodal signature and a mean radius of 19.2 ?m. The intra-cortical porosity due to Haversian canals is measured as 3.0%. Both results are in agreement with traditional histomorphometric measurements. We show that at higher resolutions one can resolve the spatial distribution of lacunae in cortical bone.
Background The investigation of receptor-ligand interactions in the cellular context presents significant technical challenges, first, to immobilize the ligand in a manner that preserves functional properties and, second, to relate ligand properties to cell adhesion and other cellular processes. Methods Ligand-mediated cell adhesion was characterized by the development of a cellulose hollow-fiber adhesion assay in which ligand (protein A) was immobilized onto the cellulose membrane as a recombinant fusion protein containing a cellulose-binding domain affinity tag. Modules containing single cellulose hollow fibers were connected to a micro-flow system for cell deposition and detachment with fluid shear stress. The cell adhesion process that occurred inside a segment of hollow fiber was observed in real time by using an inverted microscope equipped with a CCD camera and digital frame grabber. Image analysis software was developed to count cells and record digital images. Results Cell adhesion strength was characterized by counting the number of cells that were detached by application of fluid shear stress with values that ranged from 2.3 to 185 dyne/cm2. The median shear stress of detachment of KG1a cells was directly related to the duration of membrane contact and the amount of immobilized monoclonal antibody (anti-CD34). Conclusions The hollow-fiber assay provides a general method to determine functional properties of molecular domains that interact with cell surface receptors and markers
Williams, DF, Howlett, CR, Milthorpe, B & O'Donnell, MM 2004, 'Special Issue - Focus on biomaterials science in Australia', BIOMATERIALS, vol. 25, no. 20, pp. 4859-4859.View/Download from: Publisher's site
Background Automated cell recognition from histologic images is a very complex task. Traditionally, the image is segmented by some methods chosen to suit the image type, the objects are measured, and then a classifier is used to determine cell type from the object's measurements. Different classifiers have been used with reasonable success, including neural networks working with data from morphometric analysis. Methods Image data of cells were input directly into neural networks to determine the feasibility of direct classification by using pixel intensity information. Several types of neural network and their ability to work with cells in a complex patterned background were assessed for a variety of images and cell types and for the accuracy of classification. Results Inflammatory cells from animal biomaterial implants in rabbit paravertebral muscle were imaged in histologic sections. Simple, three-layer, fully connected, back-propagation neural networks and four-layer networks with two layers of a shared-weights neural network were most successful at classifying the cells from the images, with 97% and 98% correct recognition rates, respectively. Conclusions The high accuracy recognition rate shows the potential for direct classification of visual image pixel data by neural networks.
Milthorpe, B, Westermann, R & Jones, A 2002, 'Flexible image analysis system for large images', CYTOMETRY, pp. 51-51.
Ruys, AJ, Wei, M, Brandwood, A, Milthorpe, BK & Sorrell, CC 2002, 'The effects of excessive sintering on the properties of hydroxypatite', Ceramics, adding the value, vol. 1, pp. 586-590.
Zheng, Q, Milthorpe, B & Jones, A 2002, 'Direct classification of cells in images by neural networks', CYTOMETRY, pp. 95-96.
Miao, X, Ruys, AJ & Milthorpe, BK 2001, 'Hydroxyapatite-316L fibre composites prepared by vibration assisted slip casting', Journal of Materials Science, vol. 36, no. 13, pp. 3323-3332.View/Download from: Publisher's site
To prepare hydroxyapatite (HA, or HAp)-stainless steel 316L fibre composites with up to 30 vol% 316L fibres (sim1 mm long and 50 mgrm in diameter), slip casting assisted by vibration (frequency: sim55 Hz; amplitude: sim5 mm) was carried out, followed by both cold isostatic pressing (CIPing) and hot isostatic pressing (HIPing). With the addition of around 0.5 wt% sodium carboxymethylcellulose (Na-cmc), solids loadings up to 44 vol% were obtained in calcined HA powder-derived slips, which were castable only under the vibration. The slips were concentrated and viscous so that the preferential sedimentation of the dense and large 316L fibres could be avoided. Subsequent CIPing was able to increase the relative density of the cast and dried green compacts from 46% after casting to 60% after CIPing. With the dense and uniform green compacts of the HA-316L mixtures, final HIPing at 950 °C resulted in HA-316L fibre composites of 99% relative density. The HA-316L fibre composites had improved fracture toughness of 3.6 ± 0.3 MPa.m0.5, due to the bridging effect of the ductile 316L fibres. However, the mechanical strength of the composites was limited by the presence of residual thermal stresses and circumferential microcracks. The HA-316L fibre composites were biocompatible and exhibited favourable bone-bonding characteristics.
Milthorpe, B & Cooley, M 2001, 'Special issue - Cytometry on the reef: Proceedings of the 2nd Sam Latt Conference, Hamilton Island, Australia - Introduction', CYTOMETRY, vol. 43, no. 3, pp. 163-163.View/Download from: 3.0.CO;2-U">Publisher's site
Wei, M, Ruys, AJ, Milthorpe, BK, Sorrell, CC & Evan, JH 2001, 'Electrophoretic Deposition of Hydroxyapatite Coatings on Metal Substrates: A Nanoparticulate Dual-Coating Approach', Journal of Sol-Gel Science and Technology, vol. 21, no. 1-2, pp. 39-48.View/Download from: Publisher's site
Hydroxyapatite coatings can be readily deposited on metal substrates by electrophoretic deposition. However, subsequent sintering is highly problematic owing to the fact that temperatures in excess of 1100°C are required for commercial hydroxyapatite powders to achieve high density. Such temperatures damage the metal and induce metal-catalysed decomposition of the hydroxyapatite. Furthermore, the firing shrinkage of the hydroxyapatite coating on a constraining metal substrate leads to severe cracking. The present study has overcome these problems using a novel approach: the use of aged nanoparticulate hydroxyapatite sols (lower sintering temperature) and a dual coating strategy that overcomes the cracking problem. Dual layers of uncalcined hydroxyapatite (HAp) powder were electrophoretically coated on Ti, Ti6Al4V and 316L stainless steel metal substrates, sintered at 8751000°C, and characterised by SEM and XRD, and interfacial shear strength measurement. Dual coatings on stainless steel had an average high bond strength (about 23 MPa), and dual coatings on titanium and titanium alloy had moderate strengths (about 14 and 11 MPa, respectively), in comparison with the measured shear strength of bone (35 MPa). SEM and XRD demonstrated that the second layer blended seamlessly with the first and filled the cracks in the first. The superior result on stainless steel is attributed to a more appropriate thermal expansion match with hydroxyapatite, the thinner oxide layer, or a combination of these factors.
Garrett, Q, Garrett, RW & Milthorpe, BK 1999, 'Lysozyme Sorption in Hydrogel Contact Lenses', Investigative Ophthalmology & Visual Science, vol. 40, no. 5, pp. 897-903.
To examine the processes involved in formation of protein deposits on hydrogel contact lenses. METHODS: The adsorption and/or penetration of lysozyme on or into three types of contact lenses, etafilcon A, vifilcon A, and tefilcon, were investigated in vitro using a radiolabel-tracer technique, x-ray photoelectron spectroscopy, and laser scanning confocal microscopy. RESULTS: Binding of lysozyme to high-water-content, ionic contact lenses (etafilcon A and vifilcon A) was dominated by a penetration process. The extent of this penetration was a function of charge density of the lenses, so that there was a higher degree of penetration of lysozyme in etafilcon A than in vifilcon A lenses. In contrast, the binding of lysozyme to tefilcon lenses was a surface adsorption process. The adsorption and desorption kinetics showed similar trends to those found in human serum albumin (HSA) adsorption on lens surfaces. However, the extent of lysozyme adsorption on tefilcon is much higher than HSA adsorption, probably because of the self-association of lysozyme on the tefilcon lens surface. Furthermore, either penetration or adsorption of lysozyme involved reversible and irreversible processes and were both time dependent. CONCLUSIONS: Binding of lysozyme to hydrogel lenses involves surface adsorption or matrix penetration. These processes may be reversible or irreversible. The properties of the lens materials, such as charge density (ionicity) and porosity (water content) of the lenses, determine the type and rates of these processes.
Garrett, Q, Griesser, HJ, Milthorpe, BK & Garrett, RW 1999, 'Irreversible adsorption of human serum albumin to hydrogel contact lenses: a study using electron spin resonance spectroscopy', Biomaterials, vol. 20, pp. 1345-1356.View/Download from: Publisher's site
Johnson, KA, Rogers, GJ, Roe, SC, Howlett, CR, Clayton, MK, Milthorpe, BK & Schindhelm, K 1999, 'Nitrous acid pretreatment of tendon xenografts cross-linked with glutaraldehyde and sterilized with gamma irradiation', Biomaterials, vol. 20, pp. 1003-1015.View/Download from: Publisher's site
Wei, M, Ruys, AJ, Milthorpe, BK & Sorrell, CC 1999, 'Solution ripening of hydroxyapatite nanoparticles: Effects on electrophoretic deposition', Journal Of Biomedical Materials Research, vol. 45, no. 1, pp. 11-19.View/Download from: 3.0.CO;2-7">Publisher's site
Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite (Hap) coatings on metal implants. However, densification requires heating the coated metal to high temperatures, which, for commercial HAp powders, generally means at least 1200°C. At such temperatures, the metal tends to react with the HAp coating, inducing decomposition, and the strength of titanium and stainless steel implants is severely degraded. With the use of raw uncalcined nanoparticulate Hap, densification can occur at 900°-1050°C; however, such coatings are prone to cracking due to the high drying shrinkage. This problem was solved by precipitating nanoparticulate HAp by the metathesis process [10Ca(NO3)2 + 6NH4H2PO4 + 8NH4OH] and optimizing the 30 nm of nanoprecipitates by an Ostwald ripening approach, that is, by boiling and/or ambient aging in the mother liquor. While the as-precipitated nanoparticles produced severely cracked coatings, 2 h of boiling or 10 days of ambient aging ripened the gel-like mass into unagglomerated nanoparticles, which produced crack-free coatings. Since boiling enhanced particle size but ambient aging did not, crack elimination probably was due to the transition from the highly agglomerated gel-like state to the dispersed nanoparticulate state rather than to particle growth. Furthermore, boiling only reduced the amount of cracking whereas aging completely eliminated cracking.
Wei, M, Ruys, AJ, Swain, MV, Kim, SH, Milthorpe, BK & Sorrell, CC 1999, 'interfacial bond strength of electrophoretically deposited hydroxyapatite coating on metals', Journal Of Materials Science-materials In Medicine, vol. 10, pp. 401-409.View/Download from: Publisher's site
Garrett, Q, Chatelier, RC, Griesser, HJ & Milthorpe, BK 1998, 'Effect of charged groups on the adsorption and penetration of proteins onto and into carboxymethylated poly(HEMA) hydrogels', Biomaterials, vol. 19, pp. 2175-2186.View/Download from: Publisher's site
Proteins, lipids and other biomolecules interact strongly with the acrylic-based biomaterials used for contact lenses. Although hydrogels are nominally resistant to protein fouling, many studies have reported considerable amounts of protein bound to poly(2-hydroxyethylmethacrylate) (PHEMA) lenses. This study examined the binding of a series of biomolecules (tear protein analogues, mucin and cholesterol) to poly(methylmethacrylate) (PMMA) and three HEMA-based hydrogels (PHEMA, HEMA plus methacrylic acid (P(HEMAMAA)), HEMA plus methacrylic acid plus N-vinylpyrrolidone (P(HEMAMAANVP))) by use of a quartz crystal microbalance with dissipation (QCM-D) monitoring. The QCM-D estimates changes in the mass and viscous constant for the adsorbed layer through measurements of frequency and dissipation. Protein interaction with each of the test materials caused a net increase in mass of the material indicating protein binding except for lysozyme interacting with P(HEMAMAA). A net decrease in mass was observed for lysozyme interacting with P(HEMAMAA) which may be ascribed to lysozyme collapsing the hydrogel by expelling water. A net mass decrease was observed for cholesterol interacting with each of the hydrogel materials, while a mass increase was observed on PMMA.
Knepper, M, Milthorpe, BK & Moricca, S 1998, 'Interdiffusion in short-fibre reinforced hydroxyapatite ceramics', Journal Of Materials Science-materials In Medicine, vol. 9, no. 10, pp. 589-596.View/Download from: Publisher's site
Sintering in air and hot isostatic pressing are production methods regarded as being capable of producing fibre-reinforced hydroxyapatite ceramics for biomedical applications. These composites may have the advantage of improved mechanical properties and be suitable for applications in areas where there are significant levels of load on the material. The use of pure hydroxyapatite is restricted to those free of dynamical load. Obtaining improved mechanical strength is a question of the bond between the matrix phase and the fibre-reinforcement phase. However, a chemical bond between both phases, indicated by large diffusion zones, might lead to the dehydration of the hydroxyapatite leading to undesired tricalcium phosphate in the matrix resulting in a weakening of the mechanical and biological stability of the composites. Composites with three fibre types, alumina, 316L-stainless steel and titanium were prepared and sintered in air or hot isostatically pressed. A reaction zone was noted around the titanium and stainless steel fibres, but not around the alumina fibres. The reaction zone was larger for stainless steel than titanium. Hot isostatic pressing also reduced the reaction zone markedly compared to sintering in air.
Carney, FP, Morris, CA, Willcox, MDP & Milthorpe, BA 1997, 'The competitive binding of tear proteins to hydrogel lens polymers', INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, vol. 38, no. 4, pp. 982-982.
Knepper, M, Moricca, S & Milthorpe, BK 1997, 'Stability of hydroxyapatite while processing short-fibre reinforced hydroxyapatite ceramics', Biomaterials, vol. 18, no. 23, pp. 1523-1529.View/Download from: Publisher's site
Lewis, DD, Milthorpe, BK & Bellenger, CR 1997, 'Mechanical comparison of materials used for extra-capsular stabilisation of the stifle joint in dogs', Australian Veterinary Journal, vol. 75, pp. 890-896.View/Download from: Publisher's site
Madden, KN, Johnson, KA, Howlett, CR, Milthorpe, BK, Robins, G, Ikada, Y & Schindhelm, K 1997, 'Resorbable and non-resorbable augmentation devices for tenorrhaphy of xenografts in extensor tendon deficits: 12 week study', Biomaterials, vol. 18, no. 3, pp. 225-234.View/Download from: Publisher's site
Tan, A, Milthorpe, BK & Huff, JW 1997, 'A technique for quantitation of protein deposists on rigid gas permeable contact lenses', Eye and Contact Lens: science and clinical practic, vol. 23, no. 3, pp. 177-184.
Garrett, Q & Milthorpe, BK 1996, 'Human Serum Albumin Adsorption on Hydrogel Contact Lenses In Vitro', Investigative Ophthalmology & Visual Science, vol. 37, no. 13, pp. 2594-2602.
To improve the understanding of the formation of protein deposits on hydrogel lenses. METHODS: A study of protein adsorption on three commercial hydrogel contact lenses of different materials, Etafilcon A (2-hydroxyethyl methacrylate [HEMA] polymer with sodium methacrylate and 2-ethyl-2-hydroxymethyl-1,3-propanediol trimethacrylate), tefilcon (poly[HEMA] cross-linked and copolymerized with ethylene glycol dimethacrylate), and vifilcon A (methacrylic acid polymer with ethylene glycol dimethacrylate, HEMA and N-vinyl pyrrolidone) was undertaken by using a single protein solution, human serum albumin (HSA), and a radiolabel-tracer technique. RESULTS: Static adsorption leading to multilayer adsorption was observed. Complete reversibility for adsorbed HSA on lenses did not exist. Some was tightly bound, whereas most was loosely bound and could be removed easily by rinsing in phosphate-buffered saline. Irreversible adsorption of HSA on the lenses was found to be time dependent and did not reach a maximum value even after 48 hours of adsorption. The amount of HSA adsorbed on the lenses-irreversibly as well as totally adsorbed protein- was in the order of vifilcon A > tefilcon > etafilcon A. Adsorption of HSA on the lenses increases with decreasing pH (range, 7.4 to 4) but always follows the above trend with respect to the different types of lenses. CONCLUSIONS: Irreversible binding of HSA on lenses is governed by the kinetics of protein denaturation. Electrostatic interactions may not play a major role in HSA adsorption on hydrogel lenses. Some other factors, such as hydrophobic dehydration, and special monomer units, such as N-vinyl pyrrolidone in the lens materials, may favor adsorption of HSA.
HUFF, JW, MILTHORPE, BK & TAN, A 1995, 'QUANTITATION OF PROTEIN DEPOSITS ON RIGID GAS-PERMEABLE CONTACT-LENSES', INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, vol. 36, no. 4, pp. S144-S144.
Roe, SC, Milthorpe, BK, Schindhelm, K & Howlett, CR 1995, 'incorporation of chemically modified and radiation-sterilised cancellous bone allografts', Veterinary and Comparative Orthopaedics and Traumatology, vol. 8, pp. 163-169.
Ruys, AJ, Brandwood, A, Milthorpe, BK, Dickson, MR, Zeigler, KA & Sorrell, CC 1995, 'The effects of sintering atmosphere on the chemical compatibility of hydroxyapatite and particulate additives at 1200 C', Journal Of Materials Science-materials In Medicine, vol. 6, pp. 297-301.View/Download from: Publisher's site
Ruys, AJ, Sorrell, CC, Brandwood, A & Milthorpe, BK 1995, 'Hydroxyapatite sintering characteristics: correlation with powder morphology by high-resolution microscopy', Journal of Materials Science Letters, vol. 14, no. 10, pp. 744-747.
Hydroxyapatite Cal0(PO4)6(OH)2 (HAp) is a hydrated calcium phosphate ceramic that closely resembles the chemical composition of bone mineral and is therefore one of the small group of bonereplacement materials classed as bioactive, i.e. capable of bonding chemically with bone . This group includes calcium phosphate ceramics, which, although chemically similar to HAp, are generally more prone to in vitro dissolution , and certain calcium phosphate glass compositions . Thus HAp is a prime candidate for bone replacement applications.
Ruys, AJ, Wei, M, Sorrell, CC, Dickson, MR, Brandwood, A & Milthorpe, BK 1995, 'Sintering effects on the strength hydroxyapatite', Biomaterials, vol. 16, no. 5, pp. 409-415.View/Download from: Publisher's site
Garcia, JN, Milthorpe, BK, russell, D & Johnson, KA 1994, 'Biomechanical study of canine spinal fracture fixation using pins or bone screws with polymethylmethacrylate', Veterinary Surgery, vol. 23, pp. 322-329.
Jones, AS, Milthorpe, BK & Howlett, CR 1994, 'Measurement of Microtomy Induced Section Distortion and Its Correction for 3-Dimensional Histological Reconstructions', Cytometry, vol. 15, no. 2, pp. 95-105.View/Download from: Publisher's site
The presence of microtomy induced distortion in paraffin sections is a significant hindrance to the accurate alignment of sections for three-dimensional reconstructive techniques. Measurement of section distortion in various rat tissues demonstrated distortions to be present in all sections, with over 85% of such distortions being manifest as expansions when compared to the original distances between a series of eight drilled fiducial marks. Mean percentage dimensional changes in the direction of the cutting stroke and at right angles to this direction were -0.5 ± 1.5% and 3.7 ± 1.2% for liver, 7.6 ± 2.4% and 9.1 ± 1.2% for kidney, 6.6 ± 2.3% and 10.5 ± 1.4% for lung, and 20.3 ± 6.6% and 8.9 ± 5.9% for skeletal muscle. Individual sections invariably displayed measurable distortions, with only skeletal muscle showing any consistent pattern, in the form of barrel distortion at right angles to the cutting stroke. In addition a method of distortion correction and simultaneous image alignment is presented as a means of section alignment with full distortion correction capability. This method uses a quadratic polynomial transform in a non-linear unwarping algorithm, to correct for the rotational and translational misalignment as well as for microtomy and camera aspect ratio distortions. Application of this method to a sequence of 46 serial sections demonstrated an alignment accuracy to within 2.6 ± 0.8 pixels
Cell affinity separations are based on the selective attachment of cell pheno-type using antibody or lectins specific for cell surface markers. The major physico-chemical factors which influence ligand-mediated cell adhesion dynamics and the efficiency of cell affinity separation have been examined. Uniform cell detachment forces were generated with a parallel-plate flow cell (plate separation 100 m, surface area 3 cm2). Hydrodynamic shear stress was used to measure cell adhesion strength and to separate cells on the basis of surface affinity. Human cell lines grown in tissue culture were separated on a flat derivatised glass immunoadsorbent which formed the floor of the flow chamber. Flow-cell residence time, detachment shear stress, temperature, and ligand density were shown to influence cell attachment probability. An understanding of the physical basis of ligand-mediated cell adhesion provided a rationale for optimisation of affinity cell separation. At room temperature attachment of positive cells was rapid (<2 min) and adhesion strength was directly related to immunoadsorbent ligand density. Purity and recovery of enriched fractions were dependent on the separation shear stress and could be optimised using this parameter. Enrichment factors were greater than 100-fold, with at least 90% of positive cells recovered in enriched fractions. Enrichment purity and yields did not decline at higher loading densities (105 cells/cm2). Selective immunoadsorbent surface chemistry is a prerequisite for efficient affinity cell separation. Purity and recovery may be optimised by fractionating enriched and depleted cell populations with uniform fluid shear stress.
Ruys, AJ, Ehsani, BK, Milthorpe, BK & Sorrell, CC 1994, 'Effects of nonoxide additions to hydroxyapatite during sintering', International Ceramic Monographs, vol. 1, pp. 106-110.
Ruys, AJ, Wei, M, Brandwood, A, Milthorpe, BK & Sorrell, CC 1994, 'Fracture toughness of 316L stainless steel short-fibre-reinforced hydroxyapatite', Journal of the Australian Ceramics Society, vol. 30, no. 1, pp. 12-18.
Wei, M, Ruys, AJ, Brandwood, A & Milthorpe, BK 1994, 'Electrophoretic coating of metal and ceramic substrates by hydroxyapatite', International Ceramic Monographs, vol. 1, pp. 714-721.
Ketaren, PP, Batterham, ES, White, E, Farrell, DJ & Milthorpe, BK 1993, 'Phosphorus studies in pigs - 1. Available phosphorus requirements of grower/finisher pigs', British journal of Nutrition, vol. 70, pp. 249-268.View/Download from: Publisher's site
Two experiments were conducted to determine the available P requirements of grower and grower/finisher pigs and to define the conditions for conducting a growth assay for P availability. In the first experiment, diets with four levels of calculated available P (1-4 g/kg) and four Ca:available P ratios (1.7-2.9) were used to determine the available P requirements of grower pigs. The diets were formulated by substituting the required amounts of limestone and sodium tripolyphosphate for sugar in a soya-bean meal and sugar-based diet. In addition to measuring growth responses, a range of bones were examined to determine the most suitable criteria for assessing the response to available P. There was a small quadratic response of feed intake and growth rate of the pigs to level of available P, with maximum responses occurring to approximately 3 g available P/kg (P < 0.05). There were linear depressing effects of increasing Ca: available P ratios on carcass gain and feed conversion ratio (P < 0.01) but most of these effects occurred when the ratio exceeded 2-5: 1.
Ruys, AJ, Ehsani, BK, Milthorpe, BK & Sorrell, CC 1993, 'Effects of nonoxied additions on the decomposition and sintering of hydroxyapatite', Journal of the Australian Ceramics Society, vol. 29, pp. 65-69.
Ruys, AJ, Milthorpe, BK & Sorrell, CC 1993, 'Short-fibre reinforced hydroxyapatite: effects of processing on thermal stability', Journal of the Australian Ceramics Society, vol. 29, pp. 39-49.
Ruys, AJ, Wei, BK, Milthorpe, BK, Brandwood, A & Sorrell, CC 1993, 'Optimisation of fibre content in ZrO2-Fibre-Reinforced Hydroxyapatite', Journal of the Australian Ceramics Society, vol. 29, pp. 57-64.
Ruys, AJ, Wei, M, Milthorpe, BK, Brandwood, A & Sorrell, CC 1993, 'Hydrothermal sintering of ZrO2 and Al2O3 Fibre-reinforced hydroxyapatite', Journal of the Australian Ceramics Society, vol. 29, pp. 51-56.
Standard, OC, Schindhelm, K, Milthorpe, BK & Sorrell, CC 1993, 'In vitro ageing of tetragonal zirconia polycrystal (TZP) ceramics', Journal of the Australian Ceramics Society, vol. 29, pp. 54-60.
DUNSTAN, CR, SOMERS, NM, MILTHORPE, B & EVANS, RA 1992, 'BONE VIABILITY IS LOST WITH AGING IN THE FEMORAL-HEAD BUT NOT THE LUMBAR VERTEBRA - THE LOSS OF VIABILITY DOES NOT APPEAR TO AFFECT BONE COMPRESSIVE STRENGTH', JOURNAL OF BONE AND MINERAL RESEARCH, vol. 7, pp. S193-S193.
James, NL, Schindhelm, K, Slowiaczek, P, Milthorpe, B, Graham, AR, Munro, VF, Johnson, G & Steele, JG 1992, 'In vivo Patency of Endothelial Cell‐Lined Expanded Polytetrafluoroethylene Prostheses in an Ovine Model', Artificial Organs, vol. 16, no. 4, pp. 346-353.View/Download from: Publisher's site
Abstract: The performance of small‐diameter vascular prostheses may be improved by implantation of grafts lined with endothelial cells. Expanded polytetrafluoroethylene (ePTFE) prostheses (4 mm × 40 mm) were coated with fibronectin (20 γg/ml), seeded with endothelial cells, and cultured for 48 h to produce a confluent, autologous endothelial cell lining. They were implanted as carotid interposition grafts in sheep. Seeded ePTFE grafts were compared with nonseeded ePTFE grafts and autologous carotid artery grafts. No anticoagulant or antiplatelet therapy was administered. making this a stringent test model for the thromboresistance of a small‐diameter prosthesis. After 13 weeks the patencies of seeded, nonseeded, and autologous artery grafts were 16% (116), 0% (0/6), and 100% (6/6), respectively. The one seeded graft that was patent was fully lined with endothelial cells and showed no stenosis. The remaining five seeded grafts were occluded by fibrous tissue and displayed substantial spindle cell hyperplasia. There was no apparent difference between the autologous artery grafts and normal arterial tissue, and the anastomoses showed no stenosis. The ovine model provides a conservative test of prosthesis survival and may be useful for study of graft failure. © 1992 International Society for Artificial Organs
JAMES, NL, SCHINDHELM, K, SLOWIACZEK, P, MILTHORPE, B, GRAHAM, AR, MUNRO, VF, JOHNSON, G & STEELE, JG 1992, 'INVIVO PATENCY OF ENDOTHELIAL CELL-LINED EXPANDED POLYTETRAFLUOROETHYLENE PROSTHESES IN AN OVINE MODEL', ARTIFICIAL ORGANS, vol. 16, no. 4, pp. 346-353.
Roe, SC, Milthorpe, BK, True, K, Rogers, GJ & Schindhelm, K 1992, 'The effect of gamma irratiation on a xenograft tendon bioprosthesis', Clinical materials, vol. 9, pp. 149-154.
Ruys, AJ, Zeigler, KA, Milthorpe, BK & Sorrell, CC 1992, 'Hydroxylapatite-Ceramic/Metal composites: quantification of additive-induced dehydration', Ceramics, adding the value, vol. 1, pp. 591-597.
Ruys, AJ, Zeigler, KA, Milthorpe, BK & Sorrell, CC 1992, 'Proceeding of short-fibre reinforced hydroxylapatite', Ceramics, adding the value, vol. 1, pp. 598-604.
Ruys, AJ, Zeigler, KA, Standard, OC, Brandwood, A, Milthorpe, BK & Sorrell, CC 1992, 'Hydroxyapatite sintering phenomena: Densification and dehydration behaviour', Ceramics, adding the value, vol. 2, pp. 605-610.
Zeigler, KA, Ruys, AJ, Sorrell, CC, Milthorpe, BK & Brandwood, A 1992, 'Interfacial analysis of hydroxyapatite-particulate addition composites', Ceramics, adding the value, vol. 1, pp. 623-628.
James, NL, Poole-Warren, LA, Schindhelm, K, Milthorpe, BK, Mitchell, RM, Mitchell, RM & Howlett, CR 1991, 'Comparative evaluation of treated bovine pericardium as a xenograft for hernia repair', Biomaterials, vol. 12, no. Nov, pp. 801-809.
Milthorpe, BK, Schindhelm, K, Howlett, CR, Hall, PJ & Roger, GJ 1991, 'Treated xenografts as gliding tendon prostheses in an ovine model', Biomaterials, vol. 12, no. 6, pp. 577-583.
A model for testing the properties of gliding tendon grafts has been developed that allows anastomoses to be evaluated separately from the mid-portion of the graft. In addition, two different graft materials may be implanted in one sheep foreleg whilst maintaining control (not operated) tendons in both the operated leg and contralateral foreleg. The model has been used to evaluate the response of xenografts made from chemically treated kangaroo tail tendon (KTT) compared with autografts. At 3 month the mid-sections of the glutaraldehyde-fixed xenografts maintained between 57 and 82% of their initial ultimate tensile strength whereas lyophilized KTT dropped to 10% and autografts retained 91% of initial strength. Sterilization by gamma-radiation of wet xenografts did not affect the material and implant properties significantly. Longer term studies are necessary to determine the resorption behaviour of the xenografts. Anastomosis strengths were found to be about the same for all grafts, at about 25% of the strength of the original tendon. Alternatives need to be investigated to improve this strength.
Schindhelm, K, Rogers, GJ, Milthorpe, BK, Hall, PJ, Howlett, CR, Sekel, R, Goldberg, J & Viglione, W 1991, 'Autograft and Leeds-Keio reconstruction of the e anterior cruciatement', Clinical Orthopaedics and Related Research, vol. 267, pp. 278-293.
James, NL, Schindhelm, K, Slowiaczek, PR, Milthorpe, BK, Dudman, NP, Johnson, G & Steele, JG 1990, 'Endothelial cell seeding of small diameter vascular grafts', Artificial Organs, vol. 14, pp. 355-360.View/Download from: Publisher's site
Roe, SC, Milthorpe, BK & Schindhelm, K 1990, 'Collagen Cross‐Linking and Resorption: Effect of Glutaraldehyde Concentration', Artificial Organs, vol. 14, no. 6, pp. 443-448.View/Download from: Publisher's site
Abstract: Cross‐linked collagen bioprostheses usually are designed to be inert and nonresorbable, resulting in fatigue and wear failure in high‐stress environments. Eventual replacement of the implant, although minimizing strength loss during resorption, would result in a graft with reparative ability. Kangaroo tail tendon (KTT) partially cross‐linked with glutaraldehyde (GA) was evaluated in vitro for resistance to bacterial collagenase digestion and in vivo for biocompatibility and resorbability in an intramuscular implant assay. Cross‐linking was quantified by thermal denaturation studies. Incomplete cross‐linking was achieved with concentrations of GA >0.1% (w/v). KTT cross‐linked in <=0.05% GA were collagenase resistant being incompletely digested after 240 h. Cross‐linking of KTT with low concentrations of GA resulted in partial collagenase resistance and slowed resorption. © 1990 International Society for Artificial Organs
Roe, SC, Schindhelm, K & Milthorpe, BK 1990, 'Collagen resorption and cross-linking: the effect of glutaraldehyde concentration', Artificial Organs, vol. 14, pp. 443-448.View/Download from: Publisher's site
Roger, GJ, Milthorpe, BK, Muratore, A & Schindhelm, K 1990, 'Measurement of the mechanical properties of the ovine anterior cruciate ligament bone-ligament-bone complexa: basis for prosthetic evaluation', Biomaterials, vol. 11, no. March, pp. 89-96.
McAuslan, BR, Reilly, W, Hannan, G, Schindhelm, K, Milthorpe, BK & saur, BA 1988, 'Induction of endothelial cell migration by proline analogues and its relevance to angiogenesis', Experimental Cell Biology, vol. 176, pp. 248-257.
Milthorpe, BK, Roger, GJ & Schindhelm, K 1988, 'Microcomputer-based system for tensile testing of biological materials', Medical & Biological Engineering & Computing, vol. 26, no. 2, pp. 161-166.View/Download from: Publisher's site
The tensile testing of biological materials poses specific problems. Biological tissue may slip in the grips of the tensometer during tensile testing, and this needs to be taken into account in the calculation of strain. The inherent variability of tissue samples requires that a large number of samples be analysed to adequately characterise a given biological structure. These problems have been addressed by integrating a digital video dimensional analyser and a microcomputer into a system that can be attached to most tensometers. Features of the system are: automated data acquisition, analysis and filing; resolution of load and extension to better than 0·1 per cent of full scale; and achievable high throughput.
Milthorpe, BK & Schindhelm, K 1986, 'Testing of biomaterials', Australian Physical And Engineering Sciences in Medicine, vol. 9, pp. 33-37.
Schindhelm, K & Milthorpe, BK 1986, 'An overview of biomaterials', Australian Physical And Engineering Sciences in Medicine, vol. 9, pp. 29-32.
Schindhelm, K & Milthorpe, BK 1986, 'Artifical organ technology', Australian Journal of Mechanical Engineering, vol. GE10, pp. 54-58.
Rogers, GJ, Milthorpe, BK, Muratore, A & Schindhelm, K 1985, 'Measurement of the mechanical properties of the anterior cruciate ligament', Australian Physical And Engineering Sciences in Medicine, vol. 8, pp. 168-171.
Bertram, CD & Milthorpe, BK 1984, 'Optical endpoint sensing in an automatic whole blood clotting timer', Medical & Biological Engineering & Computing, vol. 22, pp. 401-405.View/Download from: Publisher's site
Most clotting time estimations are performed manually, although attempts have been made previously to automate them. The two major methods for automatically detecting the formation of the gel-like clot are mechanical (viscometric) and optical. The latter is superior in terms of accuracy of timing and freedom from artefacts but can only be performed on blood plasma. This paper describes a device which combines centrifuging to remove red cells and optical sensing of clot formation into a single operation, therepy giving activated clotting times on a par with those obtained mechanically from whole blood. The system offers the advantage over mechanical sensing that no nondisposable parts come in contact with the blood thereby eliminating e major source of timing errors. The timer works with any liquid coagulation activator, and will also time plasma clotting. The two-chambered design of the cuvette allows the activator to be kept separate from the blood until rotor startup The start of centifugal action mixes the blood and activator and starts the time. Timing is stopped auto matically when the rate of increase of optical density in the plasma, owing to fibrin formation, reaches a predetermined fevel.
Milthorpe, BK, Bertram, GD, Celler, BG & Farrell, PC 1984, 'Education and careers in biomedical engineering', Journal of Electrical & Electronics Engineering, Austr..., vol. 4, pp. 105-110.
FLICKER, W, MILTHORPE, BK, SCHINDHELM, K, ODELL, RA, MCPHERSON, J & FARRELL, PC 1982, 'COAGULATION STATUS AND PLATELET ACTIVATION WITH HEPARIN AND HEMODIALYSIS', AUSTRALIAN AND NEW ZEALAND JOURNAL OF MEDICINE, vol. 12, no. 4, pp. 327-327.
FLICKER, W, MILTHORPE, BK, SCHINDHELM, K, ODELL, RA, MCPHERSON, J & FARRELL, PC 1982, 'PLATELET FACTOR RELEASE FOLLOWING HEPARIN ADMINISTRATION AND DURING EXTRACORPOREAL-CIRCULATION', TRANSACTIONS AMERICAN SOCIETY FOR ARTIFICIAL INTERNAL ORGANS, vol. 28, pp. 431-436.
Perez, DJ, Taylor, IW, Milthorpe, BK, McGovern, VJ & Tattersall, MH 1981, 'Identification and quantitation of tumour cells in cell suspensions: a comparison of cytology and flow cytometry', British Journal Of Cancer, vol. 43, no. 4, pp. 526-531.View/Download from: Publisher's site
FLOW-CYTOMETRIC MEASUREMENTS of cell DNA content or narrow-angle light scatter (NLS) can provide a basis for discriminating neoplastic from non-neoplastic cells by identifying differences in DNA content and cell size. Flow-cytometric analyses of many human neoplasms have been previously reported (Barlogie et at., 977, 1978) showing aneuploidy in 80-90% of non-lymphoid solid tumours and 40- 60% of non-Hodgkin's lymphomas. In leukaemias, and multiple myelomas with and aneuploid tumour clone, the percentage of neoplastic cells in marrow or blood determined by DNA content correlates well with quantitation based on histologic smears (Barlogie et al., 1977; Latreille et al., 1980; Andreeff et al., 1980) but such a comparison has not been made on cell suspensions from solid tumours.
PIPER, AA, MILTHORPE, BK & FOX, RM 1981, 'MECHANISMS OF FLUOROURACIL CYTO-TOXICITY IN CULTURED HUMAN LYMPHOCYTE-T AND LYMPHOCYTE-B', CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, vol. 8, no. 4, pp. 385-385.
BROOKS, DA, MILTHORPE, B, TAYLOR, I & ZOLA, H 1980, 'HUMAN-LYMPHOCYTE ANTIGENS STUDIED BY FLOW MICROFLUORIMETRY WITH HYBRIDOMA ANTIBODIES', CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, vol. 7, no. 4, pp. 424-424.
Milthorpe, BK 1980, 'FMFPAK1: A program package for routine analysis of single parameter flow microfluorimetric data on a low cost mini-computer', Computer and Biomedical Research, vol. 13, pp. 417-429.View/Download from: Publisher's site
A program package is presented for routine analysis, on a low cost minicomputer, of data obtained by flow microfluorimetry. The programs, with the aid of a graphics capability, provide calculations of various properties of cell populations: percentage of cells in various phases of the cell-cycle (G,, S, G2 + M): mean fluorescence per cell: mean narrow-angle scatter per cell, and an approximation to relative mean volume per cell from narrow-angle light scatter measurements. The system is designed to allow either direct analysis or for storage of raw data on tape files for analysis at a later time. Provision is also made for hard copy on a digital x-y plotter.
MILTHORPE, BK, TAYLOR, IW, WOODS, RL & TATTERSALL, MHN 1980, 'MEASUREMENT OF CELLULAR DNA IN DRUG TREATED-CELLS BY FLOW MICROFLUORIMETRY', PROCEEDINGS OF THE AUSTRALIAN BIOCHEMICAL SOCIETY, vol. 13, pp. 99-99.
PIPER, AA, MCCAFFERY, CA, MILTHORPE, BK, FOX, RM & TATTERSALL, MHN 1980, 'BIOCHEMISTRY OF THE CELL-CYCLE - CELL FRACTIONATION BY CENTRIFUGAL ELUTRIATION', CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, vol. 7, no. 1, pp. 65-66.
TAYLOR, IW & MILTHORPE, BK 1980, 'AN EVALUATION OF DNA FLUOROCHROMES, STAINING TECHNIQUES AND ANALYSIS FOR FLOW MICROFLUORIMETRY OF UNPERTURBED CELL-POPULATIONS', CELL AND TISSUE KINETICS, vol. 13, no. 6, pp. 691-692.
Taylor, IW & Milthorpe, BK 1980, 'An evaluation of DNA fluorochromes, staining techniques, and analysis for flow cytometry. I. Unperturbed cell populations', Journal of Histochemistry and Cytochemistry, vol. 28, no. 11, pp. 1224-1232.View/Download from: Publisher's site
MILTHORPE, BK, NICHOL, LW & JEFFREY, PD 1977, 'SEDIMENTATION ANALYSIS OF POLYMERIZATION BEHAVIOR OF ZINC INSULIN AT PHYSIOLOGICAL PH', PROCEEDINGS OF THE AUSTRALIAN BIOCHEMICAL SOCIETY, vol. 10, pp. 10-10.
Milthorpe, BK, Nichol, LW & Jeffrey, PD 1977, 'The polymerisation pattern of Zn(II)-Insulin at pH 7.0', Biochimica et Biophysica Acta, vol. 495, pp. 195-202.
MILTHORPE, BK, NICHOL, LW & JEFFREY, PD 1976, 'POLYMERIZATION BEHAVIOR OF INSULIN AT PHYSIOLOGICAL PH', PROCEEDINGS OF THE AUSTRALIAN BIOCHEMICAL SOCIETY, vol. 9, pp. 8-8.
Nichol, LB, Jeffrey, PD & Milthorpe, BK 1976, 'The sedimentation equilibrium of heterogeneously associating systems and mixtures of non-interacting solutes: analysis without determination of molecular weight averages', Biophysical Chemistry, vol. 4, no. 3, pp. 259-267.View/Download from: Publisher's site
Sedimentation equilibrium is first considered of a system in which a ligand of any size binds to an acceptor at p sites, the experimental result, obtained with either interference or absorption optics, being a distribution of total solute concentration as a function of radial distance. Theory illustrated by a numerical example, is presented which shows that this distribution may be analysed to give the activity of the unbound ligand as a function of total weight concentration. It is shown that this information may be used together with conservation of mass equations written in terms of the initial mixing composition to evaluate the equilibrium constant(s) relevant to the system. Correlation with composition evaluation by use of absorption optics (when possible) is also discussed. The procedure does not involve solution of simultaneous equations which are sums of exponentials nor differentiation of experimental results to obtain apparent weight-average molecular weights. It is general in that it leads to the evaluation of the activity of the species characterized by the smallest M(l-Image ?) product and, accordingly, is shown to be useful in the analysis of non-interacting as well as of interacting systems.
Nichol, LW, Jeffrey, PD & Milthorpe, BK 1976, 'Analysis of sedimentation equilibrium results obtained with indefinitely self-associating systems using a procedure based on Laplace transformation', Journal of Physical Chemistry, vol. 80, no. 10, pp. 1071-1075.View/Download from: Publisher's site
Equations are developed in closed form which permit the simulation of the distribution of total concentration vs. radial distance obtainable in the sedimentation equilibrium of a system of specified initial concentration undergoing indefinite self-association. Simulated distributions obtained with a variety of systems involving one or more equilibrium constants are used to test an analysis procedure which fits the distribution to a function capable of inverse Laplace transformation and leads to a specification of the relative amounts of the species in the cell as a function of their molecular weights. It is shown that such results may be related to the equilibrium concentrations of oligomeric forms at each radial distance, thereby permitting successive equilibrium constants appropriate to the indefinite self-association to be estimated.
Milthorpe, BK, Jeffrey, PD & Nichol, LB 1975, 'The direct analysis of sedimentation equilibrium results obtained with polymerizing systems', Biophysical Chemistry, vol. 3, no. 2, pp. 169-176.View/Download from: Publisher's site
Theory is presented in relation to sedimentation equilibrium results obtained with polymerizing systems, which permits evaluation of the activity of the monomer as a function of total weight concentration. In contrast to established methods, the suggested procedure does not involve the solution of simultaneous equations which are sums of exponentials or the determination of weight-average molecular weights. A major advantage of the method is that it avoids errors inherent in differentiation and integration steps. An extrapolation to infinite dilution is involved, but this is to a defined limit and is uncomplicated by the existence of critical points in the relevant plot. The method is capable of detecting possible volume changes inherent on polymer formation, of treating systems where activity coefficients of solute species are functions of total concentration and of describing the system in terms of relevant equilibrium constants. These points and comparisons with existing methods of analysis are illustrated with numerical examples and with results obtained with lysozyme at pH 6.7. The lysozyme results are interpretable in terms of either a non-ideal monomer-dimer system or a monomer-dimer-trimer system
MILTHORPE, BK, JEFFREY, PD & NICHOL, LW 1975, 'NEW METHOD FOR CHARACTERIZING ASSOCIATING PROTEIN SYSTEMS INVOLVING SEDIMENTATION EQUILIBRIUM ANALYSIS', PROCEEDINGS OF THE AUSTRALIAN BIOCHEMICAL SOCIETY, vol. 8, pp. 24-24.
Godara, P & Milthorpe, BK 2011, 'Surgical Adhesion and Its Prevention' in Ducheyne, P, Healy, KE, Hutmacher, DW, Grainger, DW & Kirkpatrick, CJ (eds), Comprehensive Biomaterials, Elsevier, USA, pp. 561-572.View/Download from: Publisher's site
Adhesion of freely moving tissues and organs due to surgical injury and trauma can be a serious postoperative complication. High rates of incidence due to surgical intervention, especially associated with abdominal procedures, have been reported. This chapter gives an introduction to the formation of adhesions, with particular focus on peritoneum, urinary and reproductive (female) systems, tendon, ligament, joint, and pericardium. A number of techniques, treatments, and materials have been proposed for the prevention/reduction of adhesion formation. Of these, barrier methods are considered the only effective method currently available. An overview of biomaterials currently used as barriers for postsurgical tissue adhesion is presented. Current clinical practice utilizes solid membranes/mechanical barriers, spray-on, and gel and liquid barriers. These barriers can be either resorbable, nonresorbable, or a combination of both. Complications of barrier films are examined, and design criteria for barrier membranes are presented. Adhesion formation can be beneficial in particular circumstances, such as for anchoring implants, and these uses are commented upon. Much advancement has been made in this area, thanks to the increasing knowledge and understanding regarding the events that control adhesion formation, but there is still a long way to go before an optimum solution to this problem is found.
Milthorpe, BK 2005, 'Protein adsorption to surfaces and interfaces' in Vadgama, P (ed), Surfaces and interfaces for biomaterials, Woodhead Publishing Limited, Great Britain, pp. 763-781.
Piper, AA, Milthorpe, BK, Tattersall, MH & Fox, RM 1980, 'Flow microfluorimetric analysis of 5-fluorouracil induced cytotoxicity in cultured human lymphocytes: differentiation of RNA and DNA cytotoxic effects' in Tattersall, MHN & Fox, RM (eds), Nucleosides and Cancer Treatment. Rational Approaches to Antimetabolite Selectivity and Modulation, Academic Press, Sydney, pp. 266-286.
Belic, NK, Padula, M, Milthorpe, B & Santos, J 2017, 'Multiple sclerosis: a disease in a dish', MULTIPLE SCLEROSIS JOURNAL, Progress in MS Research Conference, SAGE PUBLICATIONS LTD, MS Res Australia, Sydney, AUSTRALIA, pp. NP26-NP27.
Chou, J, Hao, J, Ben-Nissan, B, Milthorpe, B & Otsuka, M 2015, 'Long-term Sustained Delivery of Zinc-doped Biomimetic System Improves Osteoporosis Condition', TISSUE ENGINEERING PART A, 4th TERMIS World Congress, MARY ANN LIEBERT, INC, Boston, MA, pp. S240-S240.
Whyte, T, Gibson, T, Milthorpe, B & Eager, D 2015, 'Full-face motorcycle helmet protection from facial impacts', AIPN 12th Injury Prevention & Safety Conference, AIPN Injury Prevention & Safety Conference, Sydney.
Green, D, Padula, M, Santos, J, Chou, J, Milthorpe, BK & Ben-Nissan, B 2012, 'A new role for marine skeletal proteins in regenerative orthopaedics', Key Engineering Materials (Volumes 529 - 530) bioceramics 24, Bioceramics, Scientific.net, Fukuoka, Japan, pp. 654-659.View/Download from: Publisher's site
Use of ready-made marine skeletons is one of the simplest possible remedies to major problems hindering the future development of regenerative orthopaedics- such as, providing a richness of framework designs and now a potentially rich, accessible source
Milthorpe, B, Lord, M & Simmons, A 2008, 'Cell-material interactions from modeling QCM-D data', 8th World Biomaterials Congress 2008, p. 1236.
Gibson, T, Bostrom, O, Kullgren, A & Milthorpe, B 2005, 'The mechanisms of early onset C5/C6 soft-tissue neck injury in rear impacts', International Research Council on the Biomechanics of Impact - 2005 International IRCOBI Conference on the Biomechanics of Impact, Proceedings, pp. 215-228.
An anatomically based, multi-body model of the C5/C6 motion segment was developed to study soft-tissue neck injury mechanisms in rear impacts. This was integrated into the MADYMO-based van der Horst head and neck model. Responses were compared with volunteer test data up to head restraint impact. Soft-tissue loading was predicted for a series of rear-end vehicle crashes with crash recorders (n=78) and known long-term pain outcomes. Facet capsule shear and impingement injury mechanisms at C5/C6 were demonstrated. Facet capsule loading correlated well with NIC max and was able to predict the risk of AIS1 neck injuries with persisting pain.
Milthorpe, BK, Jones, AC & Knackstedt, MA 2005, 'Micro-CT determination of bone ingrowth into porous bioceramics', Proceedings of the 3rd IASTED International Conference on Biomedical Engineering 2005, pp. 44-47.
For tissue engineering of bone to be successful, it is essential that the growth of bone into scaffolds be monitored accurately and in three dimensions. Microcomputed tomography is a suitable tool for this application; however, the technology for processing and analysing the images and data are not well developed. This paper examines the use of advanced image processing technology to investigate bone growth into porous bioceramic implants from a sheep model after 4 weeks. Challenges that are overcome include: accurate phase separation despite x-ray adsorption of the ingrowing tissue closely matching that of the scaffold, specifying tissue mineralisation profiles and the development of metrics that can describe in situ scaffold pore analysis and local bone healing parameters.
Jones, AC, Knackstedt, MA, Sheppard, AP, Sok, R, Hutmacher, DW, Arns, CH, Sakellariou, A, Senden, TJ, Brandwood, A & Milthorpe, BK 2004, 'Morphological examination of complex microstructure via micro-CT imaging', Transactions - 7th World Biomaterials Congress, p. 69.
The benefits of tomography over traditional techniques for the characterization of three dimensional (3D) bone morphology and interconnectivity were discussed. Computer tomography (CT) were also used to study the structure of several biomaterials on the micron scale. Phase identification techniques were applied to binarize heterogeneous datasets for analysis and visualization. Extensive morphological analysis of the three-dimensional (3D) image data was taken using a range of morphological tools to quantify pore size distributions, volume orientation and topology. The results show that three dimensional measures were useful for characterizing bone regeneration and for correlating structure with bone properties.
Lord, MS & Milthorpe, BK 2004, 'A quartz crystal microbalance study of biomolecular adsorption on polymer films', Transactions - 7th World Biomaterials Congress, p. 1378.
Artificial tear fluid deposition on 2-hydroxyethylmethacrylate-methacylic acid (PHEMA-PMAA) polymer films and polymethyl methacrylate (control PMMA) was investigated using a quartz crystal microbalance with dissipation technique. HEMA was polymerized with 5% m/m MAA as a comonomer using a cobalt (III) chain transfer agent in N-methylpyrolidone (NMP). PHEMA-PMAA was dissolved in methanol for spin casting, while PMMA was dissolved in chloroform. It was observed that for each material, the sum of individual tear components does not equal the mass of artificial tear solution deposited, indicating interactions occur between tear components. It was also observed that PMMA is subject to greater biomolecular deposition than the PHEMA-PMAA material.
Milthorpe, B, Zheng, Q & Jones, A 2004, 'Recognition of inflammatory cell types directly from colour images', CYTOMETRY PART A, 22nd Congress of the International-Society-for-Analytical-Cytology, WILEY-LISS, Montpellier, FRANCE, pp. 102-102.
Milthorpe, BK, Kao, R, Standard, O, Knackstedt, MA, Jones, AC, Sakelleriou, A & Senden, TJ 2004, 'Cortical bone ingrowth and bonding to solid and porous ceramics', Transactions - 7th World Biomaterials Congress, p. 1487.
The early ingrowth of bone into thick walled, porous hydroxyapatite (HAp), Al2O3 for potential as a bonding strategy was analyzed. Solid Al2I3 samples with 1 mm pore were formed by pressing Al2O3 powder in a specially designed mould. The samples were wrapped with carbon foil and loaded in stainless steel capsules. The porous structure HAp and porous Al2O3 bars shows interconnecting pores of a variety of sizes and interconnectivities.
Wei, T, Ruys, A & Milthorpe, B 2002, 'Hydroxyapatite-zirconia functionally graded bioceramics prepared by hot isostatic pressing', BIOCERAMICS 15, 15th International Symposium on Ceramics in Medicine, TRANS TECH PUBLICATIONS LTD, UNIV TECHNOL, SYDNEY, AUSTRALIA, pp. 591-594.View/Download from: Publisher's site
Garrett, Q, Chatelier, R, Griesser, H & Milthorpe, BK 1996, 'Irreversible binding of protein on poly(HEMA)-based hydrogel contact lenses and carboxymethyl-poly(HEMA) hydrogel discs', Transactions of the Annual Meeting of the Society for Biomaterials in conjunction with the International Biomaterials Symposium, p. 494.
The protein-contact lens polymer interactions at a fundamental level were studied with the aim of developing deposition resistant for contact lenses. Commercial hydrogel contact lenses and carboxymethyl-poly(HEMA) (CM-PHEMA) were used in the experiment. The study showed that the sign and amount of charge on the hydrogel and the protein can have a major effect on the amount of bound proteins. However, the penetration of the protein into the hydrogel and specific interaction of the protein with particular subunits in the polymer must also be considered.
Garrett, Q, Chatelier, R, Griesser, H & Milthorpe, BK 1996, 'Kinetics of irreversible binding of protein on hydrogel contact lenses', Transactions of the Annual Meeting of the Society for Biomaterials in conjunction with the International Biomaterials Symposium, p. 524.
A numerical model is employed to study the adsorption of human serum albumin (HSA) protein onto three commercial hydrogel contact lenses. The slow onset of irreversibility in the adsorption behavior of the protein was analyzed based on the assumption that native proteins bind rapidly and reversibly, then slowly denatures and adsorbs tenaciously to the polymer surface. Results suggest that the transition from reversible to irreversible adsorption is related to the denaturation of the protein on the surface of the contact lens.
Rajaai, SM, Herbert, TJ, Milthorpe, BK & Schindhelm, K 1993, 'Design of ulna head prosthesis', Proceedings of the Annual Conference on Engineering in Medicine and Biology, pp. 1099-1100.
Pathological conditions of the ulna head normally cause its instability and result in pain, weakness and limitation of movement of the wrist. In many cases excision of the ulna head is unavoidable, but excision alone may not be adequate and can cause further derangement of wrist performance. Therefore, need exists in some cases to replace the ulna head with an appropriate prosthesis. Existing ulna head prostheses have proven inadequate. The aim of this study was to establish a design for the potential development of an ulna head prosthesis. The dimensions of 100 ulnae have been recorded and classified and are the basis for design and sizing of the prosthesis. Only three prosthetic sizes are required clinically. A stress analysis has been performed for the head and stem of the prosthesis and has demonstrated adequate mechanical strength for the clinical application. The materials of construction selected for the stress analysis are alumina for the head and Ti-6Al-4V for the stem of the prosthesis.
JAMES, NL, SCHINDHELM, K, SLOWIACZEK, P, MILTHORPE, BK, GRAHAM, AR, JOHNSON, G & STEELE, JG 1990, 'COMPARISON OF ENDOTHELIAL-CELL SEEDED AND NONSEEDED EPTFE GRAFTS IN SHEEP', APPLIED CARDIOVASCULAR BIOLOGY, 1990-91, 2ND ANNUAL MEETING OF THE INTERNATIONAL SOC FOR APPLIED CARDIOVASCULAR BIOLOGY, KARGER, VENICE, ITALY, pp. 91-96.
MILTHORPE, BK, TRUE, K, SUN, L & SCHINDHELM, K 1991, 'QUANTITATIVE HISTOLOGICAL-EVALUATION OF CROSS-LINKED KANGAROO TAIL TENDON - PROGRESS AND PROBLEMS', BIOMATERIAL-TISSUE INTERFACES, 9TH EUROPEAN CONF ON BIOMATERIALS, ELSEVIER SCIENCE PUBL B V, CHESTER, ENGLAND, pp. 55-61.
MILTHORPE, BK, SCHINDHELM, K & ROE, S 1989, 'EFFECT OF GLUTARALDEHYDE CONCENTRATION ON COLLAGEN CROSS-LINKING AND ABSORPTION', CLINICAL IMPLANT MATERIALS, 8TH EUROPEAN CONF ON BIOMATERIALS : CLINICAL IMPLANT MATERIALS, ELSEVIER SCIENCE PUBL B V, HEIDELBERG, FED REP GER, pp. 1-5.
ROE, SC, MILTHORPE, BK & SCHINDHELM, K 1989, 'ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING BONE-LIGAMENT-BONE ALLOGRAFTS - AN INVITRO STUDY', CLINICAL IMPLANT MATERIALS, 8TH EUROPEAN CONF ON BIOMATERIALS : CLINICAL IMPLANT MATERIALS, ELSEVIER SCIENCE PUBL B V, HEIDELBERG, FED REP GER, pp. 461-466.
Schindhelm, K & Milthorpe, BK 1985, 'Artificial organs: engineering aspects', National Engineering Conference, Institute of Engineers Australia, Melbourne, Australia, pp. 460-470.