ORCID Profile
0000-0002-4473-487X
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Microfluidics and nanofluidics | Nanoscale characterisation | Colloid and surface chemistry | Biomedical engineering | Medical devices | Mechanobiology | Physical chemistry
Publisher: MDPI AG
Date: 14-02-2022
DOI: 10.3390/BIOS12020120
Abstract: Plasma extraction from blood is essential for diagnosis of many diseases. The critical process of plasma extraction requires removal of blood cells from whole blood. Fluid viscoelasticity promotes cell migration towards the central axis of flow due to differences in normal stress and physical properties of cells. We investigated the effects of altering fluid viscoelasticity on blood plasma extraction in a serpentine microchannel. Poly (ethylene oxide) (PEO) was dissolved into blood to increase its viscoelasticity. The influences of PEO concentration, blood dilution, and flow rate on the performance of cell focusing were examined. We found that focusing performance can be significantly enhanced by adding PEO into blood. The optimal PEO concentration ranged from 100 to 200 ppm with respect to effective blood cell focusing. An optimal flow rate from 1 to 15 µL/min was determined, at least for our experimental setup. Given less than 1% haemolysis was detected at the outlets in all experimental combinations, the proposed microfluidic methodology appears suitable for applications sensitive to haemocompatibility.
Publisher: SAGE Publications
Date: 03-08-2018
Abstract: Accumulating evidence demonstrates that subhaemolytic mechanical stresses, typical of circulatory support, induce physical and biochemical changes to red blood cells. It remains unclear, however, whether cell age affects susceptibility to these mechanical forces. This study thus examined the sensitivity of density-fractionated red blood cells to sublethal mechanical stresses. Red blood cells were isolated and washed twice, with the least and most dense fractions being obtained following centrifugation (1500 g × 5 min). Red blood cell deformability was determined across an osmotic gradient and a range of shear stresses (0.3–50 Pa). Cell deformability was also quantified before and after 300 s exposure to shear stresses known to decrease (64 Pa) or increase (10 Pa) red blood cell deformability. The time course of accumulated sublethal damage that occurred during exposure to 64 Pa was also examined. Dense red blood cells exhibited decreased capacity to deform when compared with less dense cells. Cellular response to mechanical stimuli was similar in trend for all red blood cells, independent of density however, the magnitude of impairment in cell deformability was exacerbated in dense cells. Moreover, the rate of impairment in cellular deformability, induced by 64 Pa, was more rapid for dense cells. Relative improvement in red blood cell deformability, due to low-shear conditioning (10 Pa), was consistent for both cell populations. Red blood cell populations respond differently to mechanical stimuli: older (more dense) cells are highly susceptible to sublethal mechanical trauma, while cell age (density) does not appear to alter the magnitude of improved cell deformability following low-shear conditioning.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.MVR.2021.104261
Abstract: Red blood cell (RBC) populations are inherently heterogeneous, given mature RBC lack the transcriptional machinery to re-synthesize proteins affected during in vivo aging. Clearance of older, less functional cells thus aids in maintaining consistent hemorheological properties. Scenarios occur, however, where portions of mechanically impaired RBC are re-introduced into blood (e.g., damaged from circulatory support, blood transfusion) and may alter whole blood fluid behavior. Given such perturbations are associated with poor clinical outcomes, determining the tolerable level of abnormal RBC in blood is valuable. Thus, the current study aimed to define the critical threshold of blood fluid properties to re-infused physically-impaired RBC. Cell mechanics of RBC were impaired through membrane cross-linking (glutaraldehyde) or intracellular oxidation (phenazine methosulfate). Mechanically impaired RBC were progressively re-introduced into the native cell population. Negative alterations of cellular deformability and high shear blood viscosity were observed following additions of only 1-5% rigidified RBC. Low-shear blood viscosity was conversely decreased following addition of glutaraldehyde-treated cells high-resolution microscopy of these mixed cell populations revealed decreased capacity to form reversible aggregates and decreased aggregate size. Mixed RBC populations, when exposed to supraphysiological shear, presented with compounded mechanical impairment. Collectively, key determinants of blood flow behavior are sensitive to mechanical perturbations in RBC, even when only 1-5% of the cell population is affected. Given this fraction is well-below the volume of rigidified RBC introduced during circulatory support or transfusion practice, it is plausible that some adverse events following surgery and/or transfusion may be related to impaired blood fluidity.
Publisher: Springer Science and Business Media LLC
Date: 07-12-2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 27-09-2023
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.MVR.2018.05.008
Abstract: Circulation of blood depends, in part, on the ability of red blood cells (RBCs) to aggregate, disaggregate, and deform. The primary intrinsic disaggregating force of RBCs is derived from their electronegativity, which is largely determined by sialylated glycoproteins on the plasma membrane. Given supraphysiological shear exposure - even at levels below those which induce hemolysis - alters cell morphology, we hypothesized that exposure to supraphysiological and subhemolytic shear would cleave membrane-bound sialic acid, altering the electrochemical and physical properties of RBCs, and thus increase RBC aggregation. Isolated RBCs from healthy donors (n = 20) were suspended in polyvinylpyrrolidinone. Using a Poiseuille shearing system, RBC suspensions were exposed to 125 Pa for 1.5 s for three duty-cycles. Following the first and third shear duty-cycle, s les were assessed for: RBC aggregation the ability of RBCs to aggregate independent of plasma ("aggregability") disaggregation shear rate membrane-bound sialic acid content, and cell electrophoretic mobility. Initial shear exposure significantly increased RBC aggregation, aggregability, and the shear required for rouleaux dispersion. Sialic acid concentration significantly decreased on isolated RBC membranes ghosts, and increased in the supernatant following shear. Initial shear exposure decreased the electrophoretic mobility of RBCs, decreasing the electronegative charge from -15.78 ± 0.31 to -7.55 ± 0.21 mV. Three exposures to the shear duty-cycle did not further compound altered RBC measures. A single exposure to supraphysiological and subhemolytic shear significantly decreased the electrochemical charge of the RBC membrane, concurrently increasing cell aggregation/aggregability. The cascading implications of hyperaggregation appears to potentially explain the ischemia-associated complications commonly reported following mechanical circulatory support.
Publisher: Public Library of Science (PLoS)
Date: 30-11-2016
Publisher: Wiley
Date: 18-09-2020
DOI: 10.1111/TRF.16086
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 07-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2LC00197G
Abstract: This work proposed to tune particle inertial separation in sinusoidal channels by embedding periodic obstacle microstructures and developed a cascaded inertial microfluidic device for the high-efficiency isolation of rare cells.
Publisher: SAGE Publications
Date: 07-05-2022
DOI: 10.1177/03913988221095581
Abstract: Animal blood products are routinely used as surrogates for human tissue in haemocompatibility testing of rotary blood pumps. Bovine blood is particularly attractive due to the animal’s large blood volume however, bovine red blood cells (RBC) differ substantially from those of human, both in biophysical properties and molecular composition. We aimed to determine whether differences also exist in the sensitivity of bovine RBC to a standardised shear stress protocol. Fresh blood from healthy human and bovine donors was exposed to discrete combinations of shear stress using a Couette shearing system, prior to assessment of cellular deformability and mechanical sensitivity. Each s le was exposed to 25 sublethal shear stress combinations (ranging 60–100 Pa × 5–300 s). While bovine RBC exhibited decreased maximal elongation in the absence of conditioning shear, overall deformability at lower shears was ~1.8-fold greater than human. When exposed to any conditioning shear stresses Pa (or 60–70 Pa beyond 5 s), human RBC were significantly rigidified, with greater magnitudes and prolonged exposure compounding this effect. Significantly larger shears were required to rigidify bovine RBC the most extreme shear condition (100 Pa × 300 s) resulted in approximately three-times more rigidification of human RBC than bovine (137% and 47% respectively). Bovine RBC have superior resilience to mechanical stress when compared with human. Using bovine blood in ex vivo evaluation of rotary blood pumps may thus misrepresent and overestimate device-blood success, and may also have flow-on effects for eventual users. Fresh human blood during early-phase ex vivo testing is thus recommended, given shear-inducing blood pumps are designed for humans – not cattle.
Publisher: Wiley
Date: 25-08-2020
DOI: 10.1111/MICC.12652
Publisher: Wiley
Date: 17-09-2020
DOI: 10.1111/TRF.16080
Publisher: Wiley
Date: 06-09-2017
DOI: 10.1111/AOR.12997
Abstract: Patients receiving mechanical circulatory support often present with heightened inflammation and free radical production associated with pre-existing conditions in addition to that which is due to blood interactions with nonbiological surfaces. The aim of this experimental laboratory study was to assess the deformability of red blood cells (RBC) previously exposed to oxygen free radicals and determine the susceptibility of these cells to mechanical forces. In the present study, RBC from 15 healthy donors were washed and incubated for 60 min at 37°C with 50 µM phenazine methosulfate (PMS an agent that generates superoxide within RBC). Incubated RBC and negative controls were assessed for their deformability and susceptibility to mechanical damage (using ektacytometry) prior to the application of shear stress, and also following exposure to 25 different shear conditions of varied magnitudes (shear stress 1, 4, 16, 32, 64 Pa) and durations (1, 4, 16, 32, 64 s). The salient findings demonstrate that incubation with PMS impaired important indices of RBC deformability indicating altered cell mechanics by ∼19% in all conditions (pre- and postexposure to shear stress). The typical trends in shear-mediated changes in RBC susceptibility to mechanical damage, following conditioning shear stresses, were maintained for PMS incubated and control conditions. We demonstrated that free radicals hinder the ability of RBC to deform however, RBC retained their typical mechanical response to shear stress, albeit at a decreased level compared with control following exposure to PMS. Our findings also indicate that low shear exposure may decrease cell sensitivity to mechanical damage upon subsequent shear stress exposures. As patients receiving mechanical circulatory support have elevated exposure to free radicals (which limits RBC deformability), concomitant exposure to high shear environments needs to be minimized.
Publisher: Wiley
Date: 29-12-2020
DOI: 10.1111/AOR.13877
Abstract: Despite technological advances in ventricular assist devices (VADs) to treat end‐stage heart failure, hemocompatibility remains a constant concern, with supraphysiological shear stresses an unavoidable reality with clinical use. Given that impeller rotational speed is related to the instantaneous shear within the pump housing, it is plausible that the modulation of pump speed may regulate peak mechanical shear stresses and thus ameliorate blood damage. The present study investigated the hemocompatibility of the HeartWare HVAD in three configurations typical of clinical applications: standard systemic support left VAD (LVAD), pediatric support LVAD, and pulmonary support right VAD (RVAD) conditions. Two ex vivo mock circulation blood loops were constructed using explanted HVADs, in which pump speed and external loop resistance were manipulated to reflect the flow rates and differential pressures reported in configurations for standard adult LVAD (at 3150 rev⸱min −1 ), pediatric LVAD (at 2400 rev⸱min −1 ), and adult RVAD (at 1900 rev⸱min −1 ). Using bovine blood, the mock circulation blood loops were tested at 37°C over a period of 6 hours (consistent with ASTM F1841‐97) and compared with static control. Hemocompatibility assessments were conducted for each test condition, examining hematology, hemolysis (absolute and normalized index), osmotic fragility, and blood viscosity. Regardless of configuration, continuous exposure of blood to the VAD over the 6‐hour period significantly altered hematological and rheological blood parameters, and induced increased hemolysis when compared with a static control s le. Comparison of the three operational VAD configurations identified that the adult LVAD condition—associated with the highest pump speed, flow rate, and differential pressure across the pump—resulted in increased normalized hemolysis index (NIH 0.07) when compared with the lower pump speed “off‐label” counterparts (NIH of 0.04 in pediatric LVAD and 0.01 in adult RVAD configurations). After normalizing blood residence times between configurations, pump speed was identified as the primary determinant of accumulated blood damage plausibly, blood damage could be limited by restricting pump speed to the minimum required to support matched cardiac output, but not beyond.
Publisher: Public Library of Science (PLoS)
Date: 07-01-2016
No related organisations have been discovered for Antony McNamee.
Start Date: 2024
End Date: 12-2026
Amount: $463,583.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2025
Amount: $407,907.00
Funder: Australian Research Council
View Funded Activity