ORCID Profile
0000-0002-0867-9586
Current Organisation
University of Technology Sydney
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Biomaterials | Biomedical Engineering | Composite Materials | Cellular Interactions (Incl. Adhesion, Matrix, Cell Wall) | Nanotechnology | Medical Biotechnology | Polymers | Zoology | Archaeological Science | Medical Biotechnology | Nanotechnology | Biosensor Technologies | Interdisciplinary Engineering Not Elsewhere Classified | Membrane Biology | Materials Engineering | Animal Anatomy And Histology | Cad/Cam Systems |
Biological sciences | Clinical health not specific to particular organs, diseases and conditions | Health related to ageing | Other | Manufactured products not elsewhere classified | Other manufactured products | Other | Metals (composites, coatings, bonding, etc.) | "Stone, ceramics and clay materials" | Dental health | Skeletal system and disorders (incl. arthritis) | Diagnostics
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.BIOMATERIALS.2006.05.037
Abstract: 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 21nm 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.
Publisher: Korean Society for Stem Cell Research
Date: 30-11-2017
DOI: 10.15283/IJSC17036
Publisher: Wiley
Date: 2003
DOI: 10.1002/CYTO.A.10106
Abstract: 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. 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. 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. The high accuracy recognition rate shows the potential for direct classification of visual image pixel data by neural networks.
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: Springer Science and Business Media LLC
Date: 06-02-2018
Publisher: Springer Science and Business Media LLC
Date: 30-01-2017
DOI: 10.1038/NPHYS4021
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.TIBTECH.2016.10.003
Abstract: 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.
Publisher: Elsevier BV
Date: 08-2004
Publisher: MDPI AG
Date: 20-01-2015
DOI: 10.3390/MD13010666
Publisher: Wiley
Date: 05-1994
Abstract: Cell affinity separations are based on the selective attachment of cell phenotype using antibody or lectins specific for cell surface markers. The major physicochemical 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 microns, 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 (10(5) 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.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5TB02634B
Abstract: Living organisms are skilful innovators and fabricators of materials, driven by the forces of evolution. We describe the translation process between natural material innovations and human tissue engineering.
Publisher: Springer Science and Business Media LLC
Date: 04-2004
DOI: 10.1023/B:JMSM.0000021133.48661.62
Abstract: We illustrate some of the uses of micro-computed tomography (micro-CT) to study tissue-engineered bone using a micro-CT facility for imaging and visualizing biomaterials in three dimensions (3-D). The micro-CT is capable of acquiring 3D X-ray CT images made up of 2000(3) voxels on specimens up to 5 cm in extent with resolutions down to 2 microm. This allows the 3-D structure of tissue-engineered materials to be imaged across orders of magnitude in resolution. This capability is used to examine an explanted, tissue-engineered bone material based on a polycaprolactone scaffold and autologous bone marrow cells. Imaging of the tissue-engineered bone at a scale of 1 cm and resolutions of 10 microm allows one to visualize the complex ingrowth of bone into the polymer scaffold. From a theoretical viewpoint the voxel data may also be used to calculate expected mechanical properties of the tissue-engineered implant. These observations illustrate the benefits of tomography over traditional techniques for the characterization of bone morphology and interconnectivity. As the method is nondestructive it can perform a complimentary role to current histomorphometric techniques.
Publisher: Frontiers Media SA
Date: 2016
Publisher: European Cells and Materials
Date: 25-07-2007
DOI: 10.22203/ECM.V014A01
Abstract: 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.
Publisher: Springer Science and Business Media LLC
Date: 1998
Abstract: 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.
Publisher: MDPI AG
Date: 19-07-2019
DOI: 10.3390/IJMS20143542
Abstract: The authors wish to make the following corrections to this paper [...]
Publisher: Trans Tech Publications, Ltd.
Date: 05-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.696.271
Abstract: 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 control 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.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.BIOMATERIALS.2008.10.056
Abstract: 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 s les a cutoff accessible pore radius of approximately 100 microM 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.
Publisher: Trans Tech Publications, Ltd.
Date: 05-2003
Publisher: Bentham Science Publishers Ltd.
Date: 31-03-2014
Publisher: Informa UK Limited
Date: 30-06-2016
Publisher: Elsevier BV
Date: 02-1997
DOI: 10.1016/S0142-9612(97)80995-7
Abstract: Resorbable (poly-L-lactide) and non-resorbable (polyethylene terephathalate) tendon augmentation devices (TAD) in conjunction with a pericardial adhesion barrier, were designed to strengthen tenorrhaphies and were evaluated in an ovine extensor tendon deficit model in a short term study. Fifteen centimetres of tendon were resected and replaced with kangaroo tail tendon xenografts that had been cross-linked with 0.075% glutaraldehyde (GA) at 4 degrees C for one or seven days. Compared with tenorrhaphies performed with Kessler sutures alone, both types of TAD were more effective at preventing tenorrhaphy dehiscence, and thus maintaining tendon function. Furthermore, tensile strength of TAD tenorrhaphies increased significantly between zero and twelve weeks. For xenografts cross-linked in GA for one day, the tensile strength of tenorrhaphies with the resorbable TAD rose from 38 +/- 9 N at time zero, to 116 +/- 46 N at twelve weeks, while non-resorbable TAD tenorrhaphy strength at time zero was 42 +/- 16 N and 99 +/- 27 N at twelve weeks. For xenografts cross-linked with GA for seven days, similar increases in tensile strength of tenorrhaphies, with the two types of TAD were found. As there was no significant difference in mechanical performance or tissue response between the two TAD types in the first 12 weeks, use of the resorbable poly-L-lactide device may be advantageous clinically. Tensile strengths of midsections of the tendon xenograft cross-linked for 7 days was not significantly diminished 12 weeks after implantation and these xenografts were partially remodelled around the periphery. However, the tensile strength of xenografts cross-linked for one day declined significantly between time zero (319 +/- 80 N) and twelve weeks (239 +/- 92 N), suggesting that this degree of cross-linking was inadequate for maintenance of mechanical strength. Evaluation of the performance of tenorrhaphy augmentation devices with xenografts, over a longer implantation period, is required to further understand their usefulness for reconstruction of traumatic tendon injuries.
Publisher: Springer Science and Business Media LLC
Date: 2005
DOI: 10.1007/S10856-005-5995-6
Abstract: 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 degrees C, but metal implants are degraded above 1000 degrees C. 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 approximately 1000 degrees C. The effects of temperature on HA-coated Ti, Ti6Al4V, and 316L stainless steel were investigated for dual coatings of metathesis HA sintered at 1000 degrees C. 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 degrees C < T 10 microm) comprising a TiO2 oxidation zone and a CaTiO2 reaction zone.
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/0142-9612(95)98859-C
Abstract: Mechanisms underlying temperature-strength interrelations for dense (> 95% dense, pores closed) hydroxyapatite (HAp) were investigated by comparative assessment of temperature effects on tensile strength, Weibull modulus, apparent density, decomposition (HAp:tricalcium phosphate ratio), dehydroxylation and microstructure. Significant dehydroxylation occurred above approximately 800 degrees C. Strength peaked at approximately 80 MPa just before the attainment of closed porosity (approximately 95% dense). For higher temperatures (closed porosity), the strength dropped sharply to approximately 60 MPa due to the closure of dehydroxylation pathways, and then stabilized at approximately 60 MPa. At very high temperatures (> 1350 degrees C), the strength dropped catastrophically to approximately 10 MPa corresponding to the decomposition of HAp to tricalcium phosphate and the associated sudden release of the remaining bonded water.
Publisher: MDPI AG
Date: 08-03-2022
DOI: 10.3390/LIFE12030392
Abstract: Mesenchymal stem cells are a continually expanding area in research and clinical applications. Their usefulness and capacity to differentiate into various cells, particularly neural types, has driven the research area for several years. Neural differentiation has considerable usefulness. There are several successful differentiation techniques of mesenchymal stem cells that employ the use of small molecules, growth factors and commercially available kits and supplements. Phenotyping, molecular biology, genomics and proteomics investigation revealed a wealth of data about these cells during neurogenic differentiation. However, there remain large gaps in the knowledge base, particularly related to cytokines and how their role, drive mechanisms and the downstream signalling processes change with their varied expression throughout the differentiation process. In this study, adult mesenchymal stem cells were induced with neurogenic differentiation media, the cellular changes monitored by live-cell microscopy and the changes in cytokine expression in the intracellular region, secretion into the media and in the extracellular vesicle cargo were examined and analysed bioinformatically. Through this analysis, the up-regulation of key cytokines was revealed, and several neuroprotective and neurotrophic roles were displayed. Statistically significant molecules IFN-G, IL1B, IL6, TNF-A, have roles in astrocyte development. Furthermore, the cytokine bioinformatics suggests the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway is upregulated, supporting differentiation toward an astroglial lineage.
Publisher: Elsevier BV
Date: 12-1998
DOI: 10.1016/S0142-9612(98)00125-2
Abstract: A range of carboxymethylated poly(hydroxyethyl methacrylate) (CM-PHEMA) hydrogels with varying degrees of carboxymethylation was synthesized for a systematic study of the effects of ionized groups ('charge') on the uptake by hydrogel matrices of the proteins, lysozyme and human serum albumin (HSA). Using a radiolabel-tracer technique, X-ray photoelectron spectroscopy, and laser scanning confocal microscopy, we attempted to differentiate between protein molecules that were irreversibly adsorbed onto the hydrogel surface and those that penetrated into the hydrogel matrix. The effective pore size of the CM-PHEMA hydrogels was modelled and compared with the known molecular dimensions of the two proteins. The effects of the presence of varying amounts of ionized groups in the hydrogel matrix differed for the two proteins. For lysozyme, increased uptake was observed at higher carboxymethylation this is interpreted as resulting from a combination of electrostatic attraction and increasing ease of penetration of the protein into the more porous hydrogel matrix. For HSA, on the other hand, the uptake was primarily by surface adsorption, with little diffusive penetration into the matrix.
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.BIOMATERIALS.2007.01.046
Abstract: 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. Pore size distributions defined by both the local pore geometry and by the largest accessible pore show distinctly different behavior. The accessible pore size is strongly correlated to bone ingrowth. In the specimens studied a strong enhancement of bone ingrowth is observed for pore diameters>100 microm. Little difference in bone ingrowth is measured with different scaffold design. This result illustrates the benefits of microtomography for analyzing the 3D structure of scaffolds and the resultant bone ingrowth.
Publisher: Wiley
Date: 03-11-2014
DOI: 10.1111/CLR.12520
Abstract: The aim of this study was to investigate the bone regenerative properties of a heat treated cross-linked GBR membrane with zinc hydroxyapatite powders in the rat calvarial defect model over a 6-week period. In vitro physio-chemical characterization involved X-ray diffraction analysis, surface topology by scanning electron microscopy, and zinc release studies in physiological buffers. Bilateral rat calvarial defects were used to compare the Zn-HAp membranes against the commercially available collagen membranes and the unfilled defect group through radiological and histological evaluation. The synthesized Zn-MEM (100 μm thick) showed no zinc ions released in the phosphate buffer solution (PBS) buffer, but zinc was observed under acidic conditions. At 6 weeks, both the micro-CT and histological analyses revealed that the Zn-MEM group yielded significantly greater bone formation with 80 ± 2% of bone filled, as compared with 60 ± 5% in the collagen membrane and 40 ± 2% in the unfilled control group. This study demonstrated the use of heat treatment as an alternative method to cross-linking the Zn-MEM to be applied as a GBR membrane. Its synthesis and production are relatively simple to fabricate, and the membrane had rough surface features on one side, which might be beneficial for cellular activities. In a rat calvarial defect model, it was shown that new bone formation was accelerated in comparison with the collagen membrane and the unfilled defect groups. These results would suggest that Zn-MEM has the potential for further development in dental applications.
Publisher: Wiley
Date: 09-1994
DOI: 10.1111/J.1532-950X.1994.TB00491.X
Abstract: Five configurations of pins or screws interconnected with polymethylmethacrylate (PMMA) were applied to isolated canine lumbar spines (L2 to L5) in which a complete fracture-luxation had been produced at L3 to L4. Twenty-five repaired spines and five intact control spines were subjected to four-point bending and tested once to failure in ventral flexion. The purpose of this study was to determine the effects of pin number, pin angle, and use of 3.5-mm cortical bone screws instead of smooth 3.2-mm diameter pins on rigidity and ultimate strength of spinal fractures repaired by the implant-PMMA fixation technique. Bending moment versus the angular deformation curves were recorded. Rigidity, bending moment at 10 degrees angular deformation, moment at failure, and deformation at failure of each type of fixation were compared using analysis of variance. Spinal segments stabilized with eight pin-PMMA fixation had significantly greater rigidity and strength at failure than four pin-PMMA fixations (P < .05). Furthermore, spinal segments stabilized with eight pins angled away from the fracture failed at significantly greater bending moment than those with eight pins angled toward the fracture (P < .05). However, for four-pin fixation, greater strength was achieved by angling pins in the bone toward the fracture site (P < .05). Screw-PMMA fixations failed by screw bending and were less rigid and weaker at failure than the corresponding configuration of pin-PMMA fixation (P < .05).
Publisher: Elsevier BV
Date: 06-2020
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: MDPI AG
Date: 04-03-2020
DOI: 10.3390/CELLS9030619
Abstract: 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.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2006
Publisher: Wiley
Date: 26-11-2012
Abstract: 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.
Publisher: Elsevier BV
Date: 07-1995
DOI: 10.1016/0142-9612(95)99643-Z
Abstract: Strength and function of autogenic and xenogenic reconstruction of digital extensor tendons was examined in an ovine model. In this study, tendon-graft junctions were formed by either suture augmented with a woven polyester tube (A), or augmented and shielded from surrounding tissues by chemically-treated bovine pericardium (S). By 12 wk, both A and S sheep had returned to full range of motion. Mechanical strength of both the autograft-host and xenograft-host repair sites was similar, with a pooled strength of 131 +/- 25 N (n = 15). Similarly, the mid-portion xenograft strengths were constant at approximately 366 +/- 97 N (n = 7). In contrast, mid-portion autograft strengths decreased from 380 +/- 110 N (N = 4) to 120 +/- 66 N (n = 4) if shielding was omitted. The loss in autograft strength was attributed to loss of function associated with adhesions. The use of the augmentation device coupled with an adhesion barrier gives higher initial reconstruction strength and improved function during the host repair period up to 12 wk.
Publisher: MDPI AG
Date: 15-07-2020
DOI: 10.3390/IJMS21144990
Abstract: 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.
Publisher: Hindawi Limited
Date: 16-04-2014
DOI: 10.1002/TERM.1901
Abstract: 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 s les 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 CO(3)(2-) with PO(4)(3-). 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.
Publisher: Elsevier BV
Date: 09-2004
Publisher: MDPI AG
Date: 09-07-2020
DOI: 10.3390/IJMS21144867
Abstract: 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 ision 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.
Publisher: Elsevier BV
Date: 12-1997
DOI: 10.1016/S0142-9612(97)80003-8
Abstract: Reinforcement by short fibres has been adapted from modern ceramic processing technologies to achieve an improvement of structural properties of hydroxyapatite. However, the influence of the reinforcement fibres on the thermochemical behaviour of the hydroxyapatite has yet to be clarified comprehensively. Titanium, alumina and 316L-stainless steel, all materials with a proven record as implant materials, were chosen as reinforcement materials. Short fibres of these materials were incorporated in a matrix of hydroxyapatite to toughen the hydroxyapatite. Composites were processed by sintering in air, hot isostatic pressing and a method combining sintering in inert gas atmosphere and hot isostatic pressing.
Publisher: Mary Ann Liebert Inc
Date: 02-2013
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00253388
Publisher: Mary Ann Liebert Inc
Date: 10-2016
Abstract: 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.
Publisher: Springer Science and Business Media LLC
Date: 03-11-2018
Publisher: Hindawi Limited
Date: 20-06-2013
DOI: 10.1002/TERM.1784
Abstract: 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 s le 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 can be prolonged with an apatite coating to significantly promote relevant bone formation.
Publisher: Oxford University Press (OUP)
Date: 12-2004
Publisher: Hindawi Limited
Date: 08-2012
DOI: 10.1002/TERM.1544
Abstract: The determination of trace element concentrations, as well as their distribution in different biomaterials aimed for clinical applications, is a challenging task in both the areas of biological and materials research. In this research, LA-ICP-MS was employed for image mapping of the trace element distribution in a hydrothermally converted coralline hydroxyapatite material aimed for tissue-scaffolding applications. Quantification using synthetic matrix-matched standards was successfully applied for the determination and distribution of elements of interest, Sr and Mg, that influences the mechanical and biological properties of hydroxyapatite-based bone graft materials. The results showed that the instrument can successfully analyse trace elements and a relatively good image can be produced that identifies their distribution. The LA-ICP-MS method can provide an easy and effective tool, in the field of biomaterials with respect to distribution of trace elements, to better understand tissue-implant interactions, and will open up a new window for in vitro and in vivo analysis and imaging of different tissues and structures.
Publisher: Elsevier BV
Date: 06-1999
DOI: 10.1016/S0142-9612(98)90187-9
Abstract: Collagenous xenografts made from kangaroo tail tendon cross-linked with glutaraldehyde have a potential application in the reconstruction of massive digital tendon deficits. However, a limitation to the clinical use of these xenografts has been the optimization of collagen cross-linking, and subsequent bio-incorporation and retention of mechanical properties following implantation. The purpose of this study was to evaluate the effect of nitrous acid on modulating the biologic and mechanical properties of tendon xenografts cross-linked with glutaraldehyde. Tendon xenografts were pretreated with 0.1 or 0.01 M nitrous acid solution, prior to cross-linking in 2% glutaraldehyde and sterilization by gamma irradiation. Xenografts were implanted intramuscularly in rabbits to examine biocompatability, and also used to repair ovine digital extensor tendon deficits to evaluate functional incorporation. Histologically, intramuscularly implanted nitrous acid pretreated xenografts in rabbits had a greater degree of diffuse cellular infiltration into interstitial splits in the graft than controls after 12 weeks. Xenografts implanted in an ovine extensor tendon deficit were evaluated after 26 and 52 weeks. Rate of failure of tenorrhaphies between host tendon and xenografts overall (15/21) was significantly greater (P < 0.05) than for autografts (1/21), suggesting that the holding power of sutures in xenografts was inferior to that obtained in autografts. Tensile failure stress of midsections of both nitrous acid pretreated and control xenografts was about 100 MPa prior to implantation (time zero). After 26 and 52 weeks, failure stress of both types of xenografts was significantly less than at time zero (P < 0.05). At 52 weeks, failure stress of nitrous acid pretreated xenografts (47.4 +/- 3.1 MPa) was significantly less than control xenografts (63.7 +/- 5.4 MPa) (P < 0.05). However, nitrous acid pretreated xenografts were similar to control xenografts in failure load (357 +/- 29 and 354 +/- 26 N, respectively), but they tended to have larger cross-sectional areas (7.6 +/- 0.5 versus 5.7 +/- 0.6 mm2, respectively) which were responsible for the lower calculated value for failure stress. Histologically, autografts maintained their normal tissue architecture and evoked a more limited cellular response in surrounding tissues than xenografts (P < 0.05). Both types of xenograft were surrounded by a thicker cuff of cellular response than autografts. However, compared to control xenografts, nitrous acid pretreated xenografts had more extensive fragmentation and splitting of collagen bundles, and more diffuse cellular and vascular infiltration into these interstitial splits, and these alterations were apparently contributing to the greater 'swelling' of these xenografts. It was concluded that pretreatment of tendon xenografts with nitrous acid modulated their biologic and material properties. Further studies are needed to elucidate the mechanism of these effects, and to determine if the protocol for tendon xenograft preparation could be optimized for improved clinical performance.
Publisher: MDPI AG
Date: 10-04-2013
DOI: 10.3390/MD11041203
Publisher: Wiley
Date: 2001
DOI: 10.1002/1097-0320(20010301)43:3<163::AID-CYTO1043>3.0.CO;2-U
Publisher: Wiley
Date: 2003
DOI: 10.1002/CYTO.A.10091
Abstract: 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. 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. 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). The hollow-fiber assay provides a general method to determine functional properties of molecular domains that interact with cell surface receptors and markers.
Publisher: MDPI AG
Date: 26-01-2019
DOI: 10.3390/IJMS20030523
Abstract: 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.
Publisher: Wiley
Date: 04-11-2009
DOI: 10.1002/JBM.A.32219
Abstract: The modulation of biological interactions with artificial surfaces is a vital aspect of biomaterials research. Serum protein adsorption onto photoreactive hyaluronic acid (Hyal-N(3)) and its sulfated derivative (HyalS-N(3)) 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-N(3) compared with Hyal-N(3). Fibronectin was adsorbed onto HyalS-N(3) 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-N(3). This was confirmed by reduced cell adhesion on fibronectin precoated Hyal-N(3) compared with fibronectin precoated HyalS-N(3). Minimal cell adhesion was observed on albumin and serum precoated Hyal-N(3). The quartz crystal microbalance confirmed that specific cell-surface interactions were experienced by cells interacting with the fibronectin precoated polymers and serum precoated HyalS-N(3).
Publisher: MDPI AG
Date: 28-07-2023
Abstract: Neurological diseases are among the leading causes of disability and death worldwide and remain difficult to treat. Tissue engineering offers avenues to test potential treatments however, the development of biologically accurate models of brain tissues remains challenging. Given their neurogenic potential and availability, adipose-derived stem cells (ADSCs) are of interest for creating neural models. While progress has been made in differentiating ADSCs into neural cells, their differentiation in 3D environments, which are more representative of the in vivo physiological conditions of the nervous system, is crucial. This can be achieved by modulating the 3D matrix composition and stiffness. Human ADSCs were cultured for 14 days in a 1.1 kPa polyethylene glycol-based 3D hydrogel matrix to assess effects on cell morphology, cell viability, proteome changes and spontaneous neural differentiation. Results showed that cells continued to proliferate over the 14-day period and presented a different morphology to 2D cultures, with the cells elongating and aligning with one another. The proteome analysis revealed 439 proteins changed in abundance by .5 fold. Cyclic nucleotide 3′-phosphodiesterase (CNPase) markers were identified using immunocytochemistry and confirmed with proteomics. Findings indicate that ADSCs spontaneously increase neural marker expression when grown in an environment with similar mechanical properties to the central nervous system.
Publisher: Figshare
Date: 2018
Publisher: BMJ
Date: 03-03-2016
DOI: 10.1136/INJURYPREV-2015-041925
Abstract: 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.
Publisher: Trans Tech Publications, Ltd.
Date: 11-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.529-530.461
Abstract: 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 being the centre of focus in drug delivery developments. This study examines the in-vivo effects of simvastatin released from β-TCP macrospheres derived from coral exoxskeletons. The results indicates that the controlled release of simvastatin can promote bone formation comparable with direct injection. Furthermore the results showed that the release of simvastatin delivery rates can be controlled by additional coating of an apatite coating. Analysis by CT scans, SEM, amount of new bone formed and mechanical strength tests, showed that by controlling the release of simvastatin bone formation can be stimulated to a therapeutic level.
Publisher: Springer Science and Business Media LLC
Date: 04-2005
DOI: 10.1007/S10856-005-0630-0
Abstract: 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 500 microm. 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.
Publisher: Pharmaceutical Society of Japan
Date: 2013
Abstract: 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.
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 12-1997
DOI: 10.1111/J.1751-0813.1997.TB11260.X
Abstract: The mechanical properties of three materials (No. 2 polypropylene, No. 5 polybutilate-coated multifilament polyester and 18, 27 and 36 kg test monofilament nylon leader material) commonly used for extra-capsular stabilisation of the stifle in dogs with cranial cruciate ligament insufficiency were determined. The ability of No. 5 polybutilate-coated multifilament polyester and 36 kg test monofilament nylon leader material, when placed as extra-capsular sutures, to mitigate cranial drawer was evaluated in hindlimbs of cadavers. An in vitro mechanical study. Seven pairs of hindlimbs harvested from adult greyhound dogs recently euthanased for other reasons. S les of each material, including s les of 27 kg test leader material that had been sterilised by one of three methods (ethylene oxide, one or five cycles in an auto-clave), were loaded to determine tensile and stress relaxation properties. The effect of cyclic loading on a No. 5 polybutilate-coated multifilament polyester and 36 kg test leader material was also determined. Using the harvested hindlimbs, cranial drawer was measured before and after transection of the cranial cruciate ligament and on the first and twelfth cycle following extra-capsular stabilisation with either No. 5 polybutilate-coated multifilament suture or 36 kg test leader material. Leader material was found to have the most suitable mechanical characteristics for use as extracapsular stabilisation of the cranial cruciate ligament deficient stifle. Of the sterilisation methods, ethylene oxide was found to have the least detrimental effects on the handling and material characteristics of the leader material. Stifles stabilised with 36 kg test leader material had significantly less drawer than those stabilised with No. 5 polybutilate-coated multifilament polyester suture. Monofilament nylon leader material would appear to have suitable mechanical properties for extra-capsular stabilisation of the cranial cruciate ligament deficient stifle. If possible the material should be sterilised using ethylene oxide.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2009
Publisher: Wiley
Date: 02-1994
Abstract: The presence of microtomy induced distortion in paraffin sections is a significant hindrance to the accurate alignment of sections for three-dimensional reconstructive techniques. Measurements 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. In idual 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.
Publisher: Bioscientifica
Date: 02-2004
Abstract: Inhibin was first identified as a gonad-derived regulator of pituitary FSH however, it has subsequently been shown to be a tumour suppressor in the gonad and adrenal glands. Whereas non-malignant regions of human primary prostate carcinomas express inhibin alpha-subunit (INHA), malignant tissues lack INHA transcript and protein, which is consistent with epigenetic regulation of the inhibin alpha-subunit gene (INHA) promoter. This study investigated whether methylation of the INHA promoter was responsible for inactivation of INHA transcription and translation in the prostate cancer cell lines, LNCaP, DU145 and PC3. Methylation of the promoter was revealed by bisulphite genomic sequencing and use of inhibitors of methylation and histone deacetylation resulted in reactivation of the INHA transcription and translation. Significant (P .05) downregulation of a luciferase reporter gene downstream from a methylated INHA promoter compared with unmethylated INHA promoter occurred in vitro. The data demonstrate that promoter methylation is associated with downregulation of the INHA gene in prostate cancer cell lines, which is consistent with its tumour suppressive role. Therefore INHA has a significant role in prostate tumorigenesis.
Publisher: Elsevier BV
Date: 2004
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2008
DOI: 10.1142/S0219519408002590
Abstract: 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.
Publisher: Public Library of Science (PLoS)
Date: 18-01-2013
Publisher: Springer Science and Business Media LLC
Date: 1999
Abstract: Hydroxyapatite (HAp) coatings were deposited onto substrates of metal biomaterials (Ti, Ti6Al4V, and 316L stainless steel) by electrophoretic deposition (EPD). Only ultra-high surface area HAp powder, prepared by the metathesis method 10Ca(NO3)2 + 6(NH4)2HPO4 + 8NH4OH), could produce dense coatings when sintered at 875-1000degreesC. Single EPD coatings cracked during sintering owing to the 15-18% sintering shrinkage, but the HAp did not decompose. The use of dual coatings (coat, sinter, coat, sinter) resolved the cracking problem. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) inspection revealed that the second coating filled in the "valleys" in the cracks of the first coating. The interfacial shear strength of the dual coatings was found, by ASTM F1044-87, to be approximately 12 MPa on a titanium substrate and approximately 22 MPa on 316L stainless steel, comparing quite favorably with the 34 MPa benchmark (the shear strength of bovine cortical bone was found to be 34 MPa). Stainless steel gave the better result since -316L (20.5 microm mK(-1)) > alpha-HAp (approximately 14 microm mK(-1)), resulting in residual compressive stresses in the coating, whereas alpha-titanium (approximately 10.3 microm mK(-1)) < alpha-HAp, resulting in residual tensile stresses in the coating.
Publisher: Elsevier BV
Date: 07-1999
DOI: 10.1016/S0142-9612(99)00037-X
Abstract: Human serum albumin (HSA) was specifically spin labelled with 4-maleimido-tempo (MSL) at its cysteine 34 residue (HSA-MSL). The irreversible adsorption of HSA-MSL to hydrogel contact lenses (etafilcon A, tefilcon and vifilcon A) was investigated using electron spin resonance (ESR) spectroscopy. Changes in ESR spectral characteristics of adsorbed HSA-MSL as compared to HSA-MSL in solution displayed an additional immobilisation of the spin label due to the adsorption. This immobilisation of MSL corresponds to a large conformational alteration of the HSA-MSL near the modified Cys 34 residue. For both etafilcon A and tefilcon, the rate of irreversible adsorption was relatively slow compared with that of vifilcon A where the maximum state of immobilisation and hence conformational change occurred within the first hour of adsorption. Furthermore, tefilcon produced markedly different ESR spectra where a strong conformational change to a less mobile protein was apparent. This supported a model where the direct irreversible adsorption of HSA from solution dominated on tefilcon as opposed to conversion of the adsorbed protein from the reversible to the irreversible state on both etafilcon A and vifilcon A. HSA-MSL adsorption onto hydrophobic poly(methylmethacrylate) (PMMA) and hydrophilic poly(N-ter-butylacrylamide) (PTBAM) latex beads was also investigated. The spin label MSL was found to be less mobile when HSA was adsorbed onto PMMA compared with PTBAM beads. It was also found that the rate of irreversible adsorption of HSA is far higher onto PMMA surfaces than onto PTBAM surfaces.
Publisher: Hindawi Limited
Date: 27-07-2014
DOI: 10.1002/TERM.1576
Abstract: During the last two decades, biogenic mineral ions have become important additives in treatments for bone regeneration and repair. Prominent among these is strontium, which is a potent suppressor of osteoclast bone resorption. Another is magnesium, which has a key influence in mineralization processes. The shells of benthic foraminiferans, hydrothermally converted into β-TCP, have been shown to effectively release a number of bone-promoting drugs at clinically relevant levels. In this study we characterized the effects of converted foraminiferan calcium dissolution and the concomitant release profile of intrinsic strontium and magnesium. We tested the effects of strontium- and magnesium-enriched macrospheres on human osteoblast (SaOS-2) and monocytoid (U937) cell lines, which can be induced to express equivalent phagocytic activities to osteoclasts. On dissolution in a biomimetic physiological solution, the macrospheres released biologically significant quantities of calcium and phosphate ions in the first 18 days. At 3 days, during which biogenic mineral ions are released, the number of U937 osteoclast-like monocyte cells decreased, while 4 days later the osteoblast cell number increased. These results show that strontium and magnesium naturally enriched macrospheres are capable of altering the metabolic activities of the cells regulating bone homeostasis. These unique macrospheres are natural origin bone void filler particles that resorb, and release physiologically significant levels of incorporated strontium, magnesium and calcium, which together make a uniquely multifunctional in situ remedy for bone regeneration and repair and the treatment of bone-wasting diseases.
Publisher: MDPI AG
Date: 30-12-2021
DOI: 10.3390/IJMS23010397
Abstract: Cytokines are multifunctional small proteins that have a vital influence on inflammatory states of tissues and play a role in signalling and cellular control mechanisms. Cytokine expression has primarily been viewed as a form of direct secretion of molecules through an active transportation however, other forms of active transport such as extracellular vesicles are at play. This is particularly important in stem cells where signalling molecules are key to communication managing the levels of proliferation, migration, and differentiation into mature cells. This study investigated cytokines from intracellular content, direct cellular secretions, and extracellular vesicles from adult adipose-derived stem cells isolated from three distinct anatomical locations: abdomen, thigh, and chin. The cells were cultured investigated using live cell microscopy, cytokine assays, and bioinformatics analysis. The cytokines quantified and examined from each s le type showed a distinct difference between niche areas and s le types. The varying levels of TNF-alpha, IL-6 and IL-8 cytokines were shown to play a crucial role in signalling pathways such as MAPK, ERK1/2 and JAK-STAT in cells. On the other hand, the chemotactic cytokines IL-1rn, Eotaxin, IP-10 and MCP-1 showed the most prominent changes across extracellular vesicles with roles in noncanonical signalling. By examining the local and tangential roles of cytokines in stem cells, their roles in signalling and in regenerative mechanisms may be further understood.
Publisher: Hindawi Limited
Date: 15-07-2015
DOI: 10.1002/TERM.2066
Abstract: 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 alent metal ions, such as Ca
Publisher: Wiley
Date: 06-2008
Publisher: Public Library of Science (PLoS)
Date: 13-08-2013
Publisher: Elsevier BV
Date: 09-2004
Publisher: Trans Tech Publications, Ltd.
Date: 11-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.529-530.654
Abstract: 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 of osteopromotive analogues and biomineralisation proteins. It has already been shown that coral and marine sponge skeletons can support self-sustaining musculoskeletal tissues and that extracts of spongin collagen and nacre seashell organic matrices promote bone mineralisation. This should not be surprising given that the pivotal biomineralisation proteins, which orchestrate bone morphogenesis are also found in the earliest calcifying marine organisms. This is because they are representatives of the first molecular components established for calcification, morphogenesis and wound healing. In support of this notion, it has emerged that BMP molecules- the main cluster of bone growth factors for human bone morphogenesis- are secreted by endodermal cells into the developing skeleton. In addition, the regenerative signalling proteins, TGF-b and Wnt-prime targets in bone therapeutics- are also present in early marine sponge development and instrumental to stem cell activation in Cnidarians. Based on this match between vertebrate and invertebrate main developmental proteins, we review the nature and extent of this evolutionary relatedness and use it to support the development of a new strategy, which is to mine selected marine origin organic matrices for novel metabolic, signalling and structural proteins eptides and protein analogues to apply in regenerative orthopaedics, particularly when using adult stem cells. To support such a proposal we show early stage evidence-gathered in our own laboratory- of the presence of fibrinogen fragments and early osteopromotive effects of a coral organic matrix extract on stem cells. In practice the discovery of new osteopromotive and osteo-accelerant protein analogues will require use of traditional chromatography techniques, osteoactivity assays to hone in on potential proteins of significance and advanced proteomic tools to provide accurate sequencing, determine the mechanisms and molecular pathways involved in osteoactivation and determine the efficiency and effectiveness of marine skeleton-derived protein modulation of the stem cell (MSC) proteome. As more analogues are discovered using proteomic tools, skeletal organic matrices may have ever increasing utility for regenerative orthopaedics.
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00120274
Publisher: MDPI AG
Date: 26-12-2021
DOI: 10.3390/IJMS22010160
Abstract: The differentiation of human adipose derived stem cells toward a neural phenotype by small molecules has been a vogue topic in the last decade. The characterization of the produced cells has been explored on a broad scale, examining morphological and specific surface protein markers however, the lack of insight into the expression of functional proteins and their interactive partners is required to further understand the extent of the process. The phenotypic characterization by proteomic profiling allows for a substantial in-depth analysis of the molecular machinery induced and directing the cellular changes through the process. Herein we describe the temporal analysis and quantitative profiling of neural differentiating human adipose-derived stem cells after sub-proteome enrichment using a bisindolylmaleimide chemical probe. The results show that proteins enriched by the Bis-probe were identified reproducibly with 133, 118, 126 and 89 proteins identified at timepoints 0, 1, 6 and 12, respectively. Each temporal timepoint presented several shared and unique proteins relative to neural differentiation and their interactivity. The major protein classes enriched and quantified were enzymes, structural and ribosomal proteins that are integral to differentiation pathways. There were 42 uniquely identified enzymes identified in the cells, many acting as hubs in the networks with several interactions across the network modulating key biological pathways. From the cohort, it was found by gene ontology analysis that 18 enzymes had direct involvement with neurogenic differentiation.
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier
Date: 2005
Publisher: Future Medicine Ltd
Date: 06-2014
DOI: 10.2217/NNM.13.116
Abstract: Aims: 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 β-tricalcium phosphate (β-TCP) to treat clinical strain Staphylococcus aureus (MW2). Materials & methods: Foraminifera precursor materials were hydrothermally converted at 250°C for 48 h to produce β-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 containing β-TCP spheres show promise as potential bone void filler particles with antibacterial effects. Original submitted 7 February 2013 Revised submitted 9 May 2013
Publisher: MDPI AG
Date: 16-12-2013
DOI: 10.3390/MD11125148
Publisher: Wiley
Date: 04-1999
DOI: 10.1002/(SICI)1097-4636(199904)45:1<11::AID-JBM2>3.0.CO;2-7
Abstract: 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 degrees 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 degrees -1050 degrees 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 approximately 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.
Start Date: 11-2003
End Date: 12-2006
Amount: $312,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2006
End Date: 12-2008
Amount: $10,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2002
End Date: 12-2002
Amount: $296,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2004
End Date: 03-2005
Amount: $20,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2004
End Date: 12-2003
Amount: $10,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2009
End Date: 12-2010
Amount: $1,000,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2005
End Date: 12-2005
Amount: $25,500.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2005
End Date: 12-2008
Amount: $288,000.00
Funder: Australian Research Council
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