Simon Jackson - Academia.edu (original) (raw)

Papers by Simon Jackson

Biochimica Et Biophysica Acta: Molecular Basis Of Disease, Dec 1, 2002

The effects of the antibacterial peptide PR-39 on nitric oxide (NO) and liver oxygenation (pO 2) ... more The effects of the antibacterial peptide PR-39 on nitric oxide (NO) and liver oxygenation (pO 2) in a mouse model of endotoxaemia have been explored. In vivo electron paramagnetic resonance (EPR) spectroscopy was used to make direct measurements of liver NO and pO 2. Measurements of pO 2 were made at two different anatomical locations within hepatic tissue to assess effects on blood supply (hence oxygen supply) and lobule oxygenation; selectively from the liver sinusoids or an average pO 2 across the liver lobule. PR-39 induced elevated levels of liver NO at 6 h following injection of lipopolysaccharide (LPS) as a result of increased iNOS expression in liver, but had no effect on eNOS or circulatory NO metabolites. Sinusoidal oxygenation was preserved, and pO 2 across the hepatic tissue bed improved with PR-39 treatment. We propose that the beneficial effects of PR-39 on liver in this septic model were mediated by increased levels of local NO and preservation of oxygen supply to the liver sinusoids.

Scientific Reports

Despite extensive investigations, an effective treatment for sepsis remains elusive and a better ... more Despite extensive investigations, an effective treatment for sepsis remains elusive and a better understanding of the inflammatory response to infection is required to identify potential new targets for therapy. In this study we have used RNAi technology to show, for the first time, that the inducible lysophosphatidylcholine acyltransferase 2 (LPCAT2) plays a key role in macrophage inflammatory gene expression in response to stimulation with bacterial ligands. Using siRNA- or shRNA-mediated knockdown, we demonstrate that, in contrast to the constitutive LPCAT1, LPCAT2 is required for macrophage cytokine gene expression and release in response to TLR4 and TLR2 ligand stimulation but not for TLR-independent stimuli. In addition, cells transfected to overexpress LPCAT2 exhibited increased expression of inflammatory genes in response to LPS and other bacterial ligands. Furthermore, we have used immunoprecipitation and Western blotting to show that in response to LPS, LPCAT2, but not LPC...

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Atmosphere

Bioaerosol emissions arising from biowaste treatment are an issue of public concern. To better ch... more Bioaerosol emissions arising from biowaste treatment are an issue of public concern. To better characterise the bioaerosols, and to assess a range of measurement methods, we aerosolised green waste compost under controlled conditions. Viable and non-viable Andersen samplers, cyclone samplers and a real time bioaerosol detection system (Spectral Intensity Bioaerosol Sensor (SIBS)) were deployed simultaneously. The number-weighted fraction of fluorescent particles was in the range 22–26% of all particles for low and high emission scenarios. Overall fluorescence spectral profiles seen by the SIBS exhibited several peaks across the 16 wavelength bands from 298 to 735 nm. The size-fractionated endotoxin profile showed most endotoxin resided in the 2.1–9 μm aerodynamic diameter fraction, though up to 27% was found in a finer size fraction. A range of microorganisms were detected through culture, Matrix Assisted Laser Desorption and Ionisation Time of Flight Mass Spectrometry (MALDI-TOF) a...

Frontiers in pharmacology, 2018

Compared to two-dimensional (2D) cell culture, cellular aggregates or spheroids (3D) offer a more... more Compared to two-dimensional (2D) cell culture, cellular aggregates or spheroids (3D) offer a more appropriate alternative system where individual cell-cell communication and micro-environment more closely represent the organ; yet we understand little of the physiological conditions at this scale. The relationship between spheroid size and oxygen microenvironment, an important factor influencing the metabolic capacity of cells, was first established using the fish intestine derived RTgutGC cell line. Subsequently, pharmaceutical metabolism (Propranolol), as determined by high performance liquid chromatography, in this intestinal model was examined as a function of spheroid size. Co-efficient of variation between spheroid size was below 12% using the gyratory platform method, with the least variation observed in the highest cell seeding density. The viable, high oxygen micro-environment of the outer rim of the spheroid, as determined by electron paramagnetic resonance (EPR) oximetry, ...

The Science of the total environment, Jan 9, 2018

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands calle... more A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm and 0.48 cm, respectively) and the composting site (2.32 cm and 0.46 cm, respectively) and the lowest at the dairy farm (1.03 cm and 0.24 cm, respectively) and the sewage treatment works (1.03 cm and 0.25 cm, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 ...

Synthetic and systems biotechnology, 2017

Preventive medicine and food industry have shown an increased interest in the development of natu... more Preventive medicine and food industry have shown an increased interest in the development of natural antioxidants, since those most commonly used synthetic antioxidants may have restricted use in food. This could explain why there is currently much research on the antioxidant properties from natural products such as mushrooms. Many mushrooms have been reported to possess antioxidant properties, which enable them to neutralize free radicals. The oxygen molecule is a free radical, which lead to the generation of the reactive oxygen species and can damage the cells. Cell damage caused by free radicals appears to be a major contributor to aging and degenerative diseases. Mushrooms antioxidant components are found in fruit bodies, mycelium and culture both, which include polysaccharides, tocopherols, phenolics, carotenoids, ergosterol and ascorbic acid among others. Fruit bodies or mycelium can be manipulated to produce active compounds in a relatively short period of time, which represe...

Ecotoxicology (London, England), Jan 7, 2017

There is an acknowledged need for in vitro fish intestinal model to help understand dietary expos... more There is an acknowledged need for in vitro fish intestinal model to help understand dietary exposure to chemicals in the aquatic environment. The presence and use of such models is however largely restrictive due to technical difficulties in the culturing of enterocytes in general and the availability of appropriate established cell lines in particular. In this study, the rainbow trout (Oncorhynchus mykiss) intestinal derived cell line (RTgutGC) was used as a surrogate for the "gut sac" method. To facilitate comparison, RTgutGC cells were grown as monolayers (double-seeded) on permeable Transwell supports leading to a two-compartment intestinal model consisting of polarised epithelium. This two-compartment model divides the system into an upper apical (lumen) and a lower basolateral (portal blood) compartment. In our studies, these cells stained weakly for mucosubstances, expressed the tight junction protein ZO-1 in addition to E-cadherin and revealed the presence of polar...

Journal of medical microbiology, Jan 10, 2017

The Limulus amebocytelysate (LAL) assay is widely used for the screening of lipopolysaccharide (L... more The Limulus amebocytelysate (LAL) assay is widely used for the screening of lipopolysaccharide (LPS) in parenteral pharmaceuticals. However, correlation of LPS in Gram-negative bacterial infections by LAL assay has been problematic, partly due to the variable reactivity of different LPS structures. Recombinant factor C (rFC) has allowed the development of a new simple, specific and sensitive LPS detection system (PyroGene). In this work, the potential of the new assay for detecting various LPS structures has been investigated and compared with two LAL-based assays and a human monocyte activity assay. The activity of the various LPS structures has been investigated by PyroGene and two LAL-based assays and a human monocyte activity assay. The rFC assay detected most LPS structures in picogram quantities and the potency of E. coli, B. cepacia, Salmonella smooth and Salmonella R345 LPS was no different when measured with PyroGene or LAL assays. However, the reactivity of K. pneumoniae, ...

Langmuir : the ACS journal of surfaces and colloids, May 23, 2017

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for ... more Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insight...

Archives of oral biology, Jan 20, 2017

The objective of the present study was to determine the effects of concurrent LPS and cytokine pr... more The objective of the present study was to determine the effects of concurrent LPS and cytokine priming, reflective of the in vivo milieu, on macrophage production of key periodontitis associated cytokines TNF, IL-1β and IL-6. THP-1 cells were pre-treated with combinations of Porphyromonas gingivalis and Escherichia coli lipopolysaccharide (LPS), concurrently with polarising cytokines IFNγ and IL-4, or PMA as a non-polarised control. Production of key periodontitis associated cytokines in response to subsequent LPS challenge were measured by enzyme - linked immunosorbent assay. Compared with cells incubated with IFNγ or IL-4 alone in the "polarisation" phase, macrophages that were incubated with LPS during the first 24h displayed a down-regulation of TNF and IL-1β production upon secondary LPS treatment in the "activation" phase. In all three macrophage populations (M0, M1 and M2), pre-treatment with P. gingivalis LPS during the polarisation process led to a signi...

PloS one, 2017

At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacologica... more At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacological effects in fish. One particular concern for the environment is their potential to bioaccumulate and reach pharmacological levels; the study of these implications for environmental risk assessment has therefore gained increasing attention. To avoid unnecessary testing on animals, in vitro methods for assessment of xenobiotic metabolism could aid in the ecotoxicological evaluation. Here we report the use of a 3-D in vitro liver organoid culture system (spheroids) derived from rainbow trout to measure the metabolism of seven pharmaceuticals using a substrate depletion assay. Of the pharmaceuticals tested, propranolol, diclofenac and phenylbutazone were metabolised by trout liver spheroids; atenolol, metoprolol, diazepam and carbamazepine were not. Substrate depletion kinetics data was used to estimate intrinsic hepatic clearance by this spheroid model, which was similar for diclofenac and...

International Journal of Experimental Pathology, 1994

Immunobiology, Feb 1, 2004

Acyltransferases are important in the regulation of membrane phospholipid fatty acyl composition ... more Acyltransferases are important in the regulation of membrane phospholipid fatty acyl composition and together with phospholipase A2 enzymes control arachidonic acid incorporation and remodelling within phospholipids. In addition, monocyte and macrophage acyltransferase activity has been shown to respond to various inflammatory cytokines under conditions that can induce enhanced cellular responses. Work in our laboratory indicates that the enzyme lysophosphatidylcholine acyltransferase may mediate the priming reactions of monocytes to the cytokine interferon-gamma. Our recent studies suggest that this enzyme might also affect the responses of monocytes to the bacterial agent lipopolysaccharide that may be important in the development of sepsis. This article summarises the relationship between monocyte lysophosphatidylcholine acyltransferase, lipopolysaccharide and sepsis.

Macrophages and hepatocytes from normal and BCG-primed mice have been spin-labelled in their memb... more Macrophages and hepatocytes from normal and BCG-primed mice have been spin-labelled in their membranes with 5- and 16-doxyl stearic acid. Incubation of spin-labelled cells from BCG-primed animals with lipopolysaccharide from E. coli 0111.B4 produced a detectable and transient disturbance in the cell membranes as reflected by an increase in the order parameter measured from the electron spin resonance spectra of 5-doxyl-stearate. This membrane disturbance was maximal at 3-4 hours of incubation and was only detected with cells from mice primed with BCG. Spectra obtained from the 16-doxyl-stearate-labelled cells showed no change in order parameter on incubation with lipopolysaccharide.

Journal of Immunological Methods, 1998

A method to amplify and detect TNF-a mRNA from primed Mono Mac 6 cells is described. A silica-bas... more A method to amplify and detect TNF-a mRNA from primed Mono Mac 6 cells is described. A silica-based extraction system was utilised for preparation of cell extracts and specific oligonucleotide primers were designed for amplification of TNF-(r mRNA by the NASBA process. Amplification products were detected using either a liquid hybridisation assay, with analysis by polyacrylamide gel electrophoresis, or a plate hybridisation system. The method has many potential applications for the study of inflammatory cytokines and cellular mRNAs in cell culture and clinical samples.

Free Radical Biol Med, 2002

A previous report that the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) a... more A previous report that the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) allows DEPMPO radical cation formation to be detected via the production of a carbon-centred radical adduct (assigned as the cis-hydroxyethyl species, formed by an intramolecular process) is shown to be incorrect. Rather, this and other paramagnetic species arise from the facile oxidation of trace hydroxylamine impurities present in commercial DEPMPO samples. As a result, techniques for the detection and elimination of such hydroxylamine impurities from DEPMPO solutions were developed and are described; these should prove to be of general use in EPR spin trapping experiments.

PLOS ONE, 2016

Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organo... more Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells) using Electron Paramagnetic Resonance (EPR) oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc) allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL) is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen) report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (*2,500 cells/spheroid) and absolute size (118±32 μm) allow control of factors such as pre-existing stresses (e.g. * 2% normoxic/hypoxic interface) for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid) cultures in biomedical and toxicological research.

Analytical Proceedings, 1990

Biochimica Et Biophysica Acta: Molecular Basis Of Disease, Dec 1, 2002

The effects of the antibacterial peptide PR-39 on nitric oxide (NO) and liver oxygenation (pO 2) ... more The effects of the antibacterial peptide PR-39 on nitric oxide (NO) and liver oxygenation (pO 2) in a mouse model of endotoxaemia have been explored. In vivo electron paramagnetic resonance (EPR) spectroscopy was used to make direct measurements of liver NO and pO 2. Measurements of pO 2 were made at two different anatomical locations within hepatic tissue to assess effects on blood supply (hence oxygen supply) and lobule oxygenation; selectively from the liver sinusoids or an average pO 2 across the liver lobule. PR-39 induced elevated levels of liver NO at 6 h following injection of lipopolysaccharide (LPS) as a result of increased iNOS expression in liver, but had no effect on eNOS or circulatory NO metabolites. Sinusoidal oxygenation was preserved, and pO 2 across the hepatic tissue bed improved with PR-39 treatment. We propose that the beneficial effects of PR-39 on liver in this septic model were mediated by increased levels of local NO and preservation of oxygen supply to the liver sinusoids.

Scientific Reports

Despite extensive investigations, an effective treatment for sepsis remains elusive and a better ... more Despite extensive investigations, an effective treatment for sepsis remains elusive and a better understanding of the inflammatory response to infection is required to identify potential new targets for therapy. In this study we have used RNAi technology to show, for the first time, that the inducible lysophosphatidylcholine acyltransferase 2 (LPCAT2) plays a key role in macrophage inflammatory gene expression in response to stimulation with bacterial ligands. Using siRNA- or shRNA-mediated knockdown, we demonstrate that, in contrast to the constitutive LPCAT1, LPCAT2 is required for macrophage cytokine gene expression and release in response to TLR4 and TLR2 ligand stimulation but not for TLR-independent stimuli. In addition, cells transfected to overexpress LPCAT2 exhibited increased expression of inflammatory genes in response to LPS and other bacterial ligands. Furthermore, we have used immunoprecipitation and Western blotting to show that in response to LPS, LPCAT2, but not LPC...

Atmosphere

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populat... more Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is ...

Atmosphere

Bioaerosol emissions arising from biowaste treatment are an issue of public concern. To better ch... more Bioaerosol emissions arising from biowaste treatment are an issue of public concern. To better characterise the bioaerosols, and to assess a range of measurement methods, we aerosolised green waste compost under controlled conditions. Viable and non-viable Andersen samplers, cyclone samplers and a real time bioaerosol detection system (Spectral Intensity Bioaerosol Sensor (SIBS)) were deployed simultaneously. The number-weighted fraction of fluorescent particles was in the range 22–26% of all particles for low and high emission scenarios. Overall fluorescence spectral profiles seen by the SIBS exhibited several peaks across the 16 wavelength bands from 298 to 735 nm. The size-fractionated endotoxin profile showed most endotoxin resided in the 2.1–9 μm aerodynamic diameter fraction, though up to 27% was found in a finer size fraction. A range of microorganisms were detected through culture, Matrix Assisted Laser Desorption and Ionisation Time of Flight Mass Spectrometry (MALDI-TOF) a...

Frontiers in pharmacology, 2018

Compared to two-dimensional (2D) cell culture, cellular aggregates or spheroids (3D) offer a more... more Compared to two-dimensional (2D) cell culture, cellular aggregates or spheroids (3D) offer a more appropriate alternative system where individual cell-cell communication and micro-environment more closely represent the organ; yet we understand little of the physiological conditions at this scale. The relationship between spheroid size and oxygen microenvironment, an important factor influencing the metabolic capacity of cells, was first established using the fish intestine derived RTgutGC cell line. Subsequently, pharmaceutical metabolism (Propranolol), as determined by high performance liquid chromatography, in this intestinal model was examined as a function of spheroid size. Co-efficient of variation between spheroid size was below 12% using the gyratory platform method, with the least variation observed in the highest cell seeding density. The viable, high oxygen micro-environment of the outer rim of the spheroid, as determined by electron paramagnetic resonance (EPR) oximetry, ...

The Science of the total environment, Jan 9, 2018

A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands calle... more A novel dual excitation wavelength based bioaerosol sensor with multiple fluorescence bands called Spectral Intensity Bioaerosol Sensor (SIBS) has been assessed across five contrasting outdoor environments. The mean concentrations of total and fluorescent particles across the sites were highly variable being the highest at the agricultural farm (2.6 cm and 0.48 cm, respectively) and the composting site (2.32 cm and 0.46 cm, respectively) and the lowest at the dairy farm (1.03 cm and 0.24 cm, respectively) and the sewage treatment works (1.03 cm and 0.25 cm, respectively). In contrast, the number-weighted fluorescent fraction was lowest at the agricultural site (0.18) in comparison to the other sites indicating high variability in nature and magnitude of emissions from environmental sources. The fluorescence emissions data demonstrated that the spectra at different sites were multimodal with intensity differences largely at wavelengths located in secondary emission peaks for λex 280 ...

Synthetic and systems biotechnology, 2017

Preventive medicine and food industry have shown an increased interest in the development of natu... more Preventive medicine and food industry have shown an increased interest in the development of natural antioxidants, since those most commonly used synthetic antioxidants may have restricted use in food. This could explain why there is currently much research on the antioxidant properties from natural products such as mushrooms. Many mushrooms have been reported to possess antioxidant properties, which enable them to neutralize free radicals. The oxygen molecule is a free radical, which lead to the generation of the reactive oxygen species and can damage the cells. Cell damage caused by free radicals appears to be a major contributor to aging and degenerative diseases. Mushrooms antioxidant components are found in fruit bodies, mycelium and culture both, which include polysaccharides, tocopherols, phenolics, carotenoids, ergosterol and ascorbic acid among others. Fruit bodies or mycelium can be manipulated to produce active compounds in a relatively short period of time, which represe...

Ecotoxicology (London, England), Jan 7, 2017

There is an acknowledged need for in vitro fish intestinal model to help understand dietary expos... more There is an acknowledged need for in vitro fish intestinal model to help understand dietary exposure to chemicals in the aquatic environment. The presence and use of such models is however largely restrictive due to technical difficulties in the culturing of enterocytes in general and the availability of appropriate established cell lines in particular. In this study, the rainbow trout (Oncorhynchus mykiss) intestinal derived cell line (RTgutGC) was used as a surrogate for the "gut sac" method. To facilitate comparison, RTgutGC cells were grown as monolayers (double-seeded) on permeable Transwell supports leading to a two-compartment intestinal model consisting of polarised epithelium. This two-compartment model divides the system into an upper apical (lumen) and a lower basolateral (portal blood) compartment. In our studies, these cells stained weakly for mucosubstances, expressed the tight junction protein ZO-1 in addition to E-cadherin and revealed the presence of polar...

Journal of medical microbiology, Jan 10, 2017

The Limulus amebocytelysate (LAL) assay is widely used for the screening of lipopolysaccharide (L... more The Limulus amebocytelysate (LAL) assay is widely used for the screening of lipopolysaccharide (LPS) in parenteral pharmaceuticals. However, correlation of LPS in Gram-negative bacterial infections by LAL assay has been problematic, partly due to the variable reactivity of different LPS structures. Recombinant factor C (rFC) has allowed the development of a new simple, specific and sensitive LPS detection system (PyroGene). In this work, the potential of the new assay for detecting various LPS structures has been investigated and compared with two LAL-based assays and a human monocyte activity assay. The activity of the various LPS structures has been investigated by PyroGene and two LAL-based assays and a human monocyte activity assay. The rFC assay detected most LPS structures in picogram quantities and the potency of E. coli, B. cepacia, Salmonella smooth and Salmonella R345 LPS was no different when measured with PyroGene or LAL assays. However, the reactivity of K. pneumoniae, ...

Langmuir : the ACS journal of surfaces and colloids, May 23, 2017

Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for ... more Our ability to tailor the electronic properties of surfaces by nanomodification is paramount for various applications, including development of sensing, fuel cell, and solar technologies. Moreover, in order to improve the rational design of conducting surfaces, an improved understanding of structure/function relationships of nanomodifications and effect they have on the underlying electronic properties is required. Herein, we report on the tuning and optimization of the electrochemical properties of indium tin oxide (ITO) functionalized with single-walled carbon nanotubes (SWCNTs). This was achieved by controlling in situ grafting of aryl amine diazonium films on the nanoscale which were used to covalently tether SWCNTs. The structure/function relationship of these nanomodifications on the electronic properties of ITO was elucidated via time-of-flight secondary ion mass spectrometry and electrochemical and physical characterization techniques which has led to new mechanistic insight...

Archives of oral biology, Jan 20, 2017

The objective of the present study was to determine the effects of concurrent LPS and cytokine pr... more The objective of the present study was to determine the effects of concurrent LPS and cytokine priming, reflective of the in vivo milieu, on macrophage production of key periodontitis associated cytokines TNF, IL-1β and IL-6. THP-1 cells were pre-treated with combinations of Porphyromonas gingivalis and Escherichia coli lipopolysaccharide (LPS), concurrently with polarising cytokines IFNγ and IL-4, or PMA as a non-polarised control. Production of key periodontitis associated cytokines in response to subsequent LPS challenge were measured by enzyme - linked immunosorbent assay. Compared with cells incubated with IFNγ or IL-4 alone in the "polarisation" phase, macrophages that were incubated with LPS during the first 24h displayed a down-regulation of TNF and IL-1β production upon secondary LPS treatment in the "activation" phase. In all three macrophage populations (M0, M1 and M2), pre-treatment with P. gingivalis LPS during the polarisation process led to a signi...

PloS one, 2017

At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacologica... more At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacological effects in fish. One particular concern for the environment is their potential to bioaccumulate and reach pharmacological levels; the study of these implications for environmental risk assessment has therefore gained increasing attention. To avoid unnecessary testing on animals, in vitro methods for assessment of xenobiotic metabolism could aid in the ecotoxicological evaluation. Here we report the use of a 3-D in vitro liver organoid culture system (spheroids) derived from rainbow trout to measure the metabolism of seven pharmaceuticals using a substrate depletion assay. Of the pharmaceuticals tested, propranolol, diclofenac and phenylbutazone were metabolised by trout liver spheroids; atenolol, metoprolol, diazepam and carbamazepine were not. Substrate depletion kinetics data was used to estimate intrinsic hepatic clearance by this spheroid model, which was similar for diclofenac and...

International Journal of Experimental Pathology, 1994

Immunobiology, Feb 1, 2004

Acyltransferases are important in the regulation of membrane phospholipid fatty acyl composition ... more Acyltransferases are important in the regulation of membrane phospholipid fatty acyl composition and together with phospholipase A2 enzymes control arachidonic acid incorporation and remodelling within phospholipids. In addition, monocyte and macrophage acyltransferase activity has been shown to respond to various inflammatory cytokines under conditions that can induce enhanced cellular responses. Work in our laboratory indicates that the enzyme lysophosphatidylcholine acyltransferase may mediate the priming reactions of monocytes to the cytokine interferon-gamma. Our recent studies suggest that this enzyme might also affect the responses of monocytes to the bacterial agent lipopolysaccharide that may be important in the development of sepsis. This article summarises the relationship between monocyte lysophosphatidylcholine acyltransferase, lipopolysaccharide and sepsis.

Macrophages and hepatocytes from normal and BCG-primed mice have been spin-labelled in their memb... more Macrophages and hepatocytes from normal and BCG-primed mice have been spin-labelled in their membranes with 5- and 16-doxyl stearic acid. Incubation of spin-labelled cells from BCG-primed animals with lipopolysaccharide from E. coli 0111.B4 produced a detectable and transient disturbance in the cell membranes as reflected by an increase in the order parameter measured from the electron spin resonance spectra of 5-doxyl-stearate. This membrane disturbance was maximal at 3-4 hours of incubation and was only detected with cells from mice primed with BCG. Spectra obtained from the 16-doxyl-stearate-labelled cells showed no change in order parameter on incubation with lipopolysaccharide.

Journal of Immunological Methods, 1998

A method to amplify and detect TNF-a mRNA from primed Mono Mac 6 cells is described. A silica-bas... more A method to amplify and detect TNF-a mRNA from primed Mono Mac 6 cells is described. A silica-based extraction system was utilised for preparation of cell extracts and specific oligonucleotide primers were designed for amplification of TNF-(r mRNA by the NASBA process. Amplification products were detected using either a liquid hybridisation assay, with analysis by polyacrylamide gel electrophoresis, or a plate hybridisation system. The method has many potential applications for the study of inflammatory cytokines and cellular mRNAs in cell culture and clinical samples.

Free Radical Biol Med, 2002

A previous report that the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) a... more A previous report that the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) allows DEPMPO radical cation formation to be detected via the production of a carbon-centred radical adduct (assigned as the cis-hydroxyethyl species, formed by an intramolecular process) is shown to be incorrect. Rather, this and other paramagnetic species arise from the facile oxidation of trace hydroxylamine impurities present in commercial DEPMPO samples. As a result, techniques for the detection and elimination of such hydroxylamine impurities from DEPMPO solutions were developed and are described; these should prove to be of general use in EPR spin trapping experiments.

PLOS ONE, 2016

Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organo... more Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells) using Electron Paramagnetic Resonance (EPR) oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc) allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL) is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen) report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (*2,500 cells/spheroid) and absolute size (118±32 μm) allow control of factors such as pre-existing stresses (e.g. * 2% normoxic/hypoxic interface) for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid) cultures in biomedical and toxicological research.

Analytical Proceedings, 1990