Displaying publications 61 - 80 of 268 in total

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  1. Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure
    Che HX, Yeap SP, Osman MS, Ahmad AL, Lim J
    ACS Appl Mater Interfaces, 2014 Oct 8;6(19):16508-18.
    PMID: 25198872 DOI: 10.1021/am5050949
    The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure.
  2. Electrosteric stabilization and its role in cooperative magnetophoresis of colloidal magnetic nanoparticles
    Yeap SP, Ahmad AL, Ooi BS, Lim J
    Langmuir, 2012 Oct 23;28(42):14878-91.
    PMID: 23025323 DOI: 10.1021/la303169g
    A detailed study on the conflicting role that colloid stability plays in magnetophoresis is presented. Magnetic iron oxide particles (MIOPs) that were sterically stabilized via surface modification with poly(sodium 4-styrene sulfonate) of different molecular weights (i.e., 70 and 1000 kDa) were employed as our model system. Both sedimentation kinetics and quartz crystal microbalance with dissipation (QCM-D) measurements suggested that PSS 70 kDa is a better stabilizer as compared to PSS 1000 kDa. This observation is mostly attributed to the bridging flocculation of PSS 1000 kDa decorated MIOPs originated from the extended polymeric conformation layer. Later, a lab-scale high gradient magnetic separation (HGMS) device was designed to study the magnetophoretic collection of MIOPs. Our experimental results revealed that the more colloidally stable the MIOP suspension is, the harder it is to be magnetically isolated by HGMS. At 50 mg/L, naked MIOPs without coating can be easily captured by HGMS at separation efficiency up to 96.9 ± 2.6%. However, the degree of separation dropped quite drastically to 83.1 ± 1.2% and 67.7 ± 4.6%, for MIOPs with PSS 1000k and PSS 70k coating, respectively. This observation clearly implies that polyelectrolyte coating that was usually employed to electrosterically stabilize a colloidal system in turn compromises the magnetic isolation efficiency. By artificially destroying the colloidal stability of the MIOPs with ionic strength increment, the ability for HGMS to recover the most stable suspension (i.e., PSS 70k-coated MIOPs) increased to >86% at 100 mM monovalent ion (Na(+)) or at 10 mM divalent ion (Ca(2+)). This observation has verified the conflicting role of colloidal stability in magnetophoretic separation.
  3. Fulltext Predictors of breast cancer screening uptake: a pre intervention community survey in Malaysia
    Dahlui M, Gan DE, Taib NA, Pritam R, Lim J
    Asian Pac J Cancer Prev, 2012;13(7):3443-9.
    PMID: 22994775
    INTRODUCTION: Despite health education efforts to educate women on breast cancer and breast cancer screening modalities, the incidence of breast cancer and presentation at an advanced stage are still a problem in Malaysia.

    OBJECTIVES: To determine factors associated with the uptake of breast cancer screening among women in the general population.

    METHODS: This pre-intervention survey was conducted in a suburban district. All households were approached and women aged 20 to 60 years old were interviewed with pre-tested guided questionnaires. Variables collected included socio-demographic characteristics, knowledge on breast cancer and screening practice of breast cancer. Univariate and multivariate analysis were performed.

    RESULTS: 41.5% of a total of 381 respondents scored above average; the mean knowledge score on causes and risks factors of breast cancer was 3.41 out of 5 (SD1.609). 58.5% had ever practiced BSE with 32.5% performing it at regular monthly intervals. Uptake of CBE by nurses and by doctors was 40.7% and 37.3%, respectively. Mammogram uptake was 14.6%. Significant predictors of BSE were good knowledge of breast cancer (OR=2.654, 95% CI: 1.033-6.816), being married (OR=2.213, 95% CI: 1.201-4.076) and attending CBE (OR=1.729, 95% CI: 1.122-2.665). Significant predictors for CBE included being married (OR=2.161, 95% CI: 1.174-3.979), good knowledge of breast cancer (OR=2.286, 95% CI: 1.012-5.161), and social support for breast cancer screening (OR=2.312, 95% CI: 1.245-4.293). Women who had CBE were more likely to undergo mammographic screening of the breast (OR=5.744, 95% CI: 2.112-15.623), p<0.005.

    CONCLUSION: CBE attendance is a strong factor in promoting BSE and mammography, educating women on the importance of breast cancer screening and on how to conduct BSE. The currently opportunistic conduct of CBE should be extended to active calling of women for CBE.
  4. Correction: Magnetophoresis of superparamagnetic nanoparticles at low field gradient: hydrodynamic effect
    Leong SS, Ahmad Z, Lim J
    Soft Matter, 2015 Oct 14;11(38):7696.
    PMID: 26365252 DOI: 10.1039/c5sm90159f
    Correction for 'Magnetophoresis of superparamagnetic nanoparticles at low field gradient: hydrodynamic effect' by Sim Siong Leong et al., Soft Matter, 2015, 11, 6968-6980.
  5. Magnetophoresis of superparamagnetic nanoparticles at low field gradient: hydrodynamic effect
    Leong SS, Ahmad Z, Lim J
    Soft Matter, 2015 Sep 21;11(35):6968-80.
    PMID: 26234726 DOI: 10.1039/c5sm01422k
    Convective current driven by momentum transfer between magnetic nanoparticles (MNPs) and their surrounding fluid during magnetophoresis process under a low gradient magnetic field (<100 T m(-1)) is presented. This magnetophoresis induced convective flow, which imposed direct hydrodynamic effects onto the separation kinetics of the MNPs under low gradient magnetic separation (LGMS), is analogous to the natural convection found in heat transportation. Herein, we show the significance of the induced convection in controlling the transport behavior of MNPs, even at a very low particle concentration of 5 mg L(-1), and this feature can be characterized by the newly defined magnetic Grashof number. By incorporating fluid flow equations into the existing magnetophoresis model, we reveal two unique features of this convective flow associated with low gradient magnetophoresis, namely, (1) the continuous homogenization of the MNPs solution and (2) accompanying sweeping flow that accelerates the collection of MNPs. According to both simulation and experimental data, the induced convection boosts the magnetophoretic capture of MNPs by approximately 30 times compared to the situation with no convection.
  6. Successful pregnancy following aplastic anaemia
    Leong KW, Teh A, Bosco JJ, Lim J
    Postgrad Med J, 1995 Oct;71(840):625-7.
    PMID: 8545293
    Pregnancy following idiopathic aplastic anaemia is rare and is difficult to manage because of life-threatening episodes of bleeding and infections. Only a handful of cases has been reported in the literature. The pregnancies were unsuccessful in the majority. The present report describes a patient with moderately severe idiopathic aplastic anaemia who was managed with intensive haematological support leading to delivery of a healthy infant by caesarean section. Despite platelet transfusion refractoriness as a result of transfusions prior to pregnancy, adequate platelet transfusions prevented excessive bleeding. The literature is reviewed and management with platelet transfusions is discussed.
  7. Working principle and application of magnetic separation for biomedical diagnostic at high- and low-field gradients
    Leong SS, Yeap SP, Lim J
    Interface Focus, 2016 Dec 06;6(6):20160048.
    PMID: 27920891
    Magnetic separation is a versatile technique used in sample preparation for diagnostic purpose. For such application, an external magnetic field is applied to drive the separation of target entity (e.g. bacteria, viruses, parasites and cancer cells) from a complex raw sample in order to ease the subsequent task(s) for disease diagnosis. This separation process not only can be achieved via the utilization of high magnetic field gradient, but also, in most cases, low magnetic field gradient with magnitude less than 100 T m-1 is equally feasible. It is the aim of this review paper to summarize the usage of both high gradient magnetic separation and low gradient magnetic separation (LGMS) techniques in this area of research. It is noteworthy that effectiveness of the magnetic separation process not only determines the outcome of a diagnosis but also directly influences its accuracy as well as sensing time involved. Therefore, understanding the factors that simultaneously influence the efficiency of both magnetic separation process and target detection is necessary. Moreover, for LGMS, there are several important considerations that should be taken into account in order to ensure its successful implementation. Hence, this review paper aims to provide an overview to relate all this crucial information by linking the magnetic separation theory to biomedical diagnostic applications.
  8. Unified View of Magnetic Nanoparticle Separation under Magnetophoresis
    Leong SS, Ahmad Z, Low SC, Camacho J, Faraudo J, Lim J
    Langmuir, 2020 07 21;36(28):8033-8055.
    PMID: 32551702 DOI: 10.1021/acs.langmuir.0c00839
    The migration process of magnetic nanoparticles and colloids in solution under the influence of magnetic field gradients, which is also known as magnetophoresis, is an essential step in the separation technology used in various biomedical and engineering applications. Many works have demonstrated that in specific situations, separation can be performed easily with the weak magnetic field gradients created by permanent magnets, a process known as low-gradient magnetic separation (LGMS). Due to the level of complexity involved, it is not possible to understand the observed kinetics of LGMS within the classical view of magnetophoresis. Our experimental and theoretical investigations in the last years unravelled the existence of two novel physical effects that speed up the magnetophoresis kinetics and explain the observed feasibility of LGMS. Those two effects are (i) cooperative magnetophoresis (due to the cooperative motion of strongly interacting particles) and (ii) magnetophoresis-induced convection (fluid dynamics instability originating from inhomogeneous magnetic gradients). In this feature article, we present a unified view of magnetophoresis based on the extensive research done on these effects. We present the physical basis of each effect and also propose a classification of magnetophoresis into four distinct regimes. This classification is based on the range of values of two dimensionless quantities, namely, aggregation parameter N* and magnetic Grashof number Grm, which include all of the dependency of LGMS on various physical parameters (such as particle properties, thermodynamic parameters, fluid properties, and magnetic field properties). This analysis provides a holistic view of the classification of transport mechanisms in LGMS, which could be particularly useful in the design of magnetic separators for engineering applications.
  9. Magnetophoresis of Magnetic Pickering Emulsions Under Low Field Gradient: Macroscopic and Microscopic Motion
    Tham FK, Ng WM, Leong SS, Yeap SP, Low SC, Lee HL, et al.
    Langmuir, 2021 Jan 26.
    PMID: 33496594 DOI: 10.1021/acs.langmuir.0c03153
    Monodispersed iron oxide nanoparticles (IONPs) coated with polystyrenesulfonate (PSS) and cetrimonium bromide (CTAB) have been used to stabilize magnetic Pickering emulsions (MPEs). Magnetophoresis of MPEs under the influence of a low gradient magnetic field (∇B < 100 T/m) was investigated at the macroscopic and microscopic scale. At the macroscopic scale, for the case of pH 7, the MPE achieved a magnetophoretic velocity of 70.9 μm/s under the influence of ∇B at 93.8 T/m. The magnetic separation efficiency of the MPE at 90% was achieved within 30 min for pH 3, 7, and 10. At pH 10, the colloidal stability of the MPE was the lowest compared to that for pH 3 and 7. Thus, MPE at pH 10 required the shortest time for achieving the highest separation efficiency, as the MPE experienced cooperative magnetophoresis at alkaline pH. The creaming rate of the MPE at all conditions was still lower compared to magnetophoresis and was negligible in influencing its separation kinetics profiles. At the microscopic scale, the migration pathways of the MPEs (with diameters between 2.5 and 7.5 μm) undergoing magnetophoresis at ∇B ∼ 13.0 T/m were recorded by an optical microscope. From these experiments, and taking into consideration the MPE size distribution from the dynamic light scattering (DLS) measurement, we determined the averaged microscopic magnetophoretic velocity to be 7.8 ± 5.5 μm/s. By making noncooperative magnetophoresis assumptions (with negligible interactions between the MPEs along their migration pathways), the calculated velocity of individual MPEs was 9.8 μm/s. Such a value was within the percentage error of the experimental result of 7.8 ± 5.5 μm/s. This finding allows for an easy and quick estimation of the magnetophoretic velocity of MPEs at the microscale by using macroscopic separation kinetics data.
  10. The Transport Behavior of a Biflagellated Microswimmer before and after Cargo Loading
    Teng XJ, Ng WM, Chong WH, Chan DJC, Mohamud R, Ooi BS, et al.
    Langmuir, 2021 08 03;37(30):9192-9201.
    PMID: 34255525 DOI: 10.1021/acs.langmuir.1c01345
    The changes in the transport behavior of a microswimmer before and after cargo loading are crucial to understanding and control of the motion of a biohybrid microbot. In this work, we show the change in swimming behavior of biflagellated microalgae Chlamydomonas reinhardtii picking up a 4.5 μm polystyrene microbead upon collision. The microswimmer changed from linear forward motion into helical motion upon the attachment of the cargo and swam with a decreased swimming velocity. We revealed the helical motion of the microswimmer upon cargo loading due to suppression of flagella by image analysis of magnified time-lapse images of C. reinhardtii with one microbead attached at the anterior end (between the flagella). Furthered suppression on the flagellum imposed by the loading of the second cargo has led to increased oscillation per displacement traveled and decreased swimming velocity. Moreover, the microswimmer with a microbead attached at the posterior end swam with swimming velocity close to free swimming microalgae and did not exhibit helical swimming behavior. The experimental results and analysis showed that the loading location of the cargo has a great influence over the swimming behavior of the microswimmer. Furthermore, the work balance calculation and mathematical analysis based on Lighthill's model are well consistent with our experimental findings.
  11. Artificial Magnetotaxis of Microbot: Magnetophoresis versus Self-Swimming
    Ng WM, Che HX, Guo C, Liu C, Low SC, Chieh Chan DJ, et al.
    Langmuir, 2018 07 10;34(27):7971-7980.
    PMID: 29882671 DOI: 10.1021/acs.langmuir.8b01210
    An artificial magnetotactic microbot was created by integrating the microalgal cell with magnetic microbead for its potential application as biomotor in microscale environment. Here, we demonstrate the remote magnetotactic control of the microbot under a low gradient magnetic field (<100 T/m). We characterize the kinematic behavior of the microbots carrying magnetic microbeads of two different sizes, with diameter of 2 and 4.5 μm, in the absence and presence of magnetic field. In the absence of magnetic field, we observed the microbot showed a helical motion as a result of the misalignment between the thrust force and the symmetry axis after the attachment. The microbot bound with a larger magnetic microbead moved with higher translational velocity but rotated slower about its axis of rotation. The viscous force was balanced by the thrust force of the microbot, resulting in a randomized swimming behavior of the microbot at its terminal velocity. Meanwhile, under the influence of a low gradient magnetic field, we demonstrated that the directional control of the microbot was based on following principles: (1) magnetophoretic force was insignificant on influencing its perpendicular motion and (2) its parallel motion was dependent on both self-swimming and magnetophoresis, in which this cooperative effect was a function of separation distance from the magnet. As the microbot approached the magnet, the magnetophoretic force suppressed its self-swimming behavior, leading to a positive magnetotaxis of the microbot toward the source of magnetic field. Our experimental results and kinematic analysis revealed the contribution of mass density variation of particle-and-cell system on influencing its dynamical behavior.
  12. Sedimentation Kinetics of Magnetic Nanoparticle Clusters: Iron Oxide Nanospheres vs Nanorods
    Ng WM, Katiyar A, Mathivanan V, Teng XJ, Leong S, Low S, et al.
    Langmuir, 2020 May 19;36(19):5085-5095.
    PMID: 32338911 DOI: 10.1021/acs.langmuir.0c00135
    A detailed study of the sedimentation kinetics of iron oxide nanoparticle (IONP) clusters composed of nanospheres and nanorods is presented. Measurements were performed to determine the absorbance of an IONP suspension undergoing sedimentation over time by using a UV-vis spectrophotometer with simultaneous monitoring of the hydrodynamic diameter of the clusters formed with dynamic light scattering (DLS). Mathematical analysis based on Happel's spherical and cylindrical models was conducted to reveal the relationship between the settling velocity of the IONP clusters and their packing density. For the case of IONP clusters composed of rodlike particles, two distinctive phases of sedimentation were recorded, with the occurrence of rapid sedimentation at the beginning of the process (phase I) followed by a slower settling rate (phase II). In sedimentation phase II, even though the nanorod clusters had a hydrodynamic size of >500 nm, which was much larger than that of the nanosphere clusters (∼200 nm), their settling velocity of 0.0038 mm/min was still slower than that of the nanosphere clusters. Such observations were mainly a result of the packing density differences between the formed clusters; due to the end-to-end particle interactions of nanorods, the nanorod clusters were less tightly packed and more permeable. In addition to the mathematical analysis, quartz crystal microbalance with dissipation (QCM-D) was employed to measure the "softness" of the IONP clusters formed, and this physical property can be further related to their packing density. This study illustrated that for a rapidly aggregating system, such as magnetic IONPs, not only do the particle shape and size uniformity contribute to the physical properties of the particle clusters formed but also the nature of the aggregation, either end-to-end and/or side-to-side, should be carefully considered when designing a colloidally stable IONP suspension.
  13. Design and operation of magnetophoretic systems at microscale: Device and particle approaches
    Chong WH, Leong SS, Lim J
    Electrophoresis, 2021 11;42(21-22):2303-2328.
    PMID: 34213767 DOI: 10.1002/elps.202100081
    Combining both device and particle designs are the essential concepts to be considered in magnetophoretic system development. Researcher efforts are often dedicated to only one of these design aspects and neglecting the interplay between them. Herein, to bring out importance of the idea of integration between device and particle, we reviewed the working principle of magnetophoretic system (includes both device and particle design concepts). Since, the magnetophoretic force is influenced by both field gradient and magnetization volume, hence, accurate prediction of the magnetophoretic force is relying on the availability of information on both parameters. In device design, we focus on the different strategies used to create localized high-field gradient. For particle design, we emphasize on the scaling between hydrodynamic size and magnetization volume. Moreover, we also briefly discussed the importance of magnetoshape anisotropy related to particle design aspect of magnetophoretic systems. Next, we illustrated the need for integration between device and particle design using microscale applications of magnetophoretic systems, include magnetic tweezers and microfluidic systems, as our working example. On the basis of our discussion, we highlighted several promising examples of microscale magnetophoretic systems which greatly utilized the interplay between device and particle design. Further, we concluded the review with several factors that possibly resulted in the lack of research efforts related to device and particle design integration.
  14. Low-Gradient Magnetophoresis of Nanospheres and Nanorods through a Single Layer of Paper
    Law JKC, Ng WM, Chong WH, Li Q, Zhang L, Khoerunnisa F, et al.
    Langmuir, 2023 Apr 11;39(14):4904-4916.
    PMID: 36992604 DOI: 10.1021/acs.langmuir.2c03164
    The possible magnetophoretic migration of iron oxide nanoparticles through the cellulosic matrix within a single layer of paper is challenging with its underlying mechanism remained unclear. Even with the recent advancements of theoretical understanding on magnetophoresis, mainly driven by cooperative and hydrodynamics phenomena, the contributions of these two mechanisms on possible penetration of magnetic nanoparticles through cellulosic matrix of paper have yet been proven. Here, by using iron oxide nanoparticles (IONPs), both nanospheres and nanorods, we have investigated the migration kinetics of these nanoparticles through grade 4 Whatman filter paper with a particle retention of 20-25 μm. By performing droplet tracking experiments, the real-time stained area growth of the particle droplet on the filter paper, under the influences of a grade N40 NdFeB magnet, were recorded. Our results show that the spatial and temporal expansion of the IONP stain is biased toward the magnet and such an effect is dependent on (i) particle concentration and (ii) particle shape. The kinetics data were first analyzed by treating it as a radial wicking fluid, and later the IONP distribution within the cellulosic matrix was investigated by optical microscopy. The macroscopic flow front velocities of the stained area ranged from 259 μm/s to 16 040 μm/s. Moreover, the microscopic magnetophoretic velocity of nanorod cluster was also successfully measured as ∼214 μm/s. Findings in this work have indirectly revealed the strong influence of cooperative magnetophoresis and the engineering feasibility of paper-based magnetophoretic technology by taking advantage of magnetoshape anisotropy effect of the particles.
  15. Fulltext The Sources of Chemical Contaminants in Food and Their Health Implications
    Rather IA, Koh WY, Paek WK, Lim J
    Front Pharmacol, 2017;8:830.
    PMID: 29204118 DOI: 10.3389/fphar.2017.00830
    Food contamination is a matter of serious concern, as the high concentration of chemicals present in the edibles poses serious health risks. Protecting the public from the degrees of the harmfulness of contaminated foods has become a daunting task. This article highlights the causes, types, and health implications of chemical contamination in food. The food contamination could be due to naturally occurring contaminants in the environment or artificially introduced by the human. The phases of food processing, packaging, transportation, and storage are also significant contributors to food contamination. The implications of these chemical contaminants on human health are grave, ranging from mild gastroenteritis to fatal cases of hepatic, renal, and neurological syndromes. Although, the government regulates such chemicals in the eatables by prescribing minimum limits that are safe for human consumption yet measures still need to be taken to curb food contamination entirely. Therefore, a variety of food needs to be inspected and measured for the presence of chemical contaminants. The preventative measures pertaining about the food contaminants problems are pointed out and discussed.
  16. Exploring the Impact of Surface Functionalization on the Reaction, Magnetophoretic, and Collective Transport Behavior of Nanoscale Zerovalent Iron
    Ng WM, Chong WH, Abdullah AZ, Lim J
    Langmuir, 2023 Dec 05;39(48):17270-17285.
    PMID: 37976676 DOI: 10.1021/acs.langmuir.3c02358
    This study provides a systematic analysis of the transport and magnetophoretic behavior of nanoscale zerovalent iron (nZVI) particles, both bare and surface functionalized by poly(ethylene glycol) (PEG) and carboxymethyl cellulose (CMC), after undergoing a chemical reaction. Here, a simple and well-investigated chemical reaction of methyl orange (MO) degradation by nZVI was used as a model reaction system, and the sand column transport and low-gradient magnetophoretic profiles of the nanoparticles were measured before and after the reaction. The results were compared over time and analyzed in the context of extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to understand the particle interactions involved. The colloidal stability of both bare and functionalized nZVI particles was enhanced after the reaction due to the consumption of metallic Fe content, resulting in a significant drop in their magnetic properties. As a result, they exhibited improved mobility across the sand column and a slower magnetophoretic collection rate compared to the unreacted particles. Here, the colloidal filtration theory (CFT) was employed to analyze the transport behavior of nZVI particles across the packed sand column. It has been observed that the surface properties of the reacted functionalized particles changed, possibly due to the entrapment of degraded products within the polymer adlayer. Moreover, quartz crystal microbalance with dissipation (QCM-D) measurements were performed to reveal the viscoelastic contribution of the adlayer formed by both bare and functionalized nZVI particles after the reaction on influencing their transport behavior across the sand column. Finally, we proposed the implementation of a high-gradient magnetic trap (HGMT) to reduce the transport distance of the colloidally stable CMC-nZVI, both before and after the reaction. This study sheds light on the behavioral changes of iron nanoparticles after the reaction and highlights environmental concerns regarding the presence of reacted nanoparticles.
  17. Navigating the microenvironment with flip and turn under quadrupole magnetophoretic steering control: Nanosphere- and nanorod-coated microbead
    Chong WH, Chan DJC, Liu CZ, Lim J
    Electrophoresis, 2024 Mar;45(5-6):357-368.
    PMID: 38044267 DOI: 10.1002/elps.202300042
    The spatiotemporal accuracy of microscale magnetophoresis has improved significantly over the course of several decades of development. However, most of the studies so far were using magnetic microbead composed of nanosphere particle for magnetophoretic actuation purpose. Here, we developed an in-house method for magnetic sample analysis called quadrupole magnetic steering control (QMSC). QMSC was used to study the magnetophoretic behavior of polystyrene microbeads decorated with iron oxide nanospheres-coated polystyrene microbeads (IONSs-PS) and iron oxide nanorods-coated polystyrene microbeads (IONRs-PS) under the influence of a quadrupole low field gradient. During a 4-s QMSC experiment, the IONSs-PS and IONRs-PS were navigated to perform 180° flip and 90° turn formations, and their kinematic results (2 s before and 2 s after the flip/turn) were measured and compared. The results showed that the IONRs-PS suffered from significant kinematic disproportion, translating a highly uneven amount of kinetic energy from the same magnitude of magnetic control. Combining the kinematic analysis, transmission electron microscopy micrographs, and vibrating sample magnetometry measurements, it was found that the IONRs-PS experienced higher fluid drag force and had lower consistency than the IONSs-PS due to its extensive open fractal nanorod structure on the bead surface and uneven magnetization, which was attributed to its ferrimagnetic nature.
  18. Fulltext Health-Related Quality of Life Assessment in Prostate Cancer Patient Undergoing Androgen Deprivation Therapy: Real-World Experience in the READT Study
    Lim J, Ng CF, Wei Y, Ong TA, Chu PS, Chan WKW, et al.
    World J Mens Health, 2024 Apr;42(2):449-459.
    PMID: 37853536 DOI: 10.5534/wjmh.230042
    PURPOSE: To investigate the effect of androgen deprivation therapy (ADT) on health-related quality of life (HRQOL) in Asian men with all stages of prostate cancer.

    MATERIALS AND METHODS: READT (real-life evaluation of the effect of ADT in prostate cancer patients in Asia) was a multi-center, prospective observational study involving six sites across four Asian populations. We enrolled eligible prostate cancer patients, who opted for ADT alone or in combination without prior neoadjuvant or adjuvant ADT within 12 months. The EuroQoL-5 dimensions, 5 level scale (EQ-5D-5L) utility index scores and visual analog scale (VAS) were evaluated at baseline, month 6 and month 12.

    RESULTS: A total of 504 patients were recruited into READT between September 2016 and May 2020 with 52.9% diagnosed with metastatic prostate cancer. The EQ-5D-5L was evaluable in 442/504 (87.7%) of patients. Overall baseline EQ-5D-5L utility index score was 0.924 (interquartile range [IQR] 0.876-1.000). We observed a statistically significant difference in baseline EQ-5D-5L utility index score among different populations with a median EQ-5D-5L utility index score of 1 for Taiwan & Hong Kong, 0.897 for China and 0.838 for Malaysia. Similar trend was observed throughout multiple treatment time-points. Stage IV prostate cancer were significantly associated with a lower baseline EQ-5D-5L utility index score compared to stage I-III prostate cancer, producing a median disutility value of -0.080. Participants had a high median VAS (80, IQR 70-90), indicating good overall health on average during ADT initiation.

    CONCLUSIONS: The study highlights the differences in health state utility index scores among various Asian prostate cancer patients receiving ADT at real-world setting. Our findings will be informative and useful in cost-effectiveness evaluation and policy decision making.

  19. Fulltext Detection of Prostate Cancer via IR Spectroscopic Analysis of Urinary Extracellular Vesicles: A Pilot Study
    Yap XL, Wood B, Ong TA, Lim J, Goh BH, Lee WL
    Membranes (Basel), 2021 Jul 31;11(8).
    PMID: 34436354 DOI: 10.3390/membranes11080591
    Extracellular vesicles (EVs) are membranous nanoparticles naturally released from living cells which can be found in all types of body fluids. Recent studies found that cancer cells secreted EVs containing the unique set of biomolecules, which give rise to a distinctive absorbance spectrum representing its cancer type. In this study, we aimed to detect the medium EVs (200-300 nm) from the urine of prostate cancer patients using Fourier transform infrared (FTIR) spectroscopy and determine their association with cancer progression. EVs extracted from 53 urine samples from patients suspected of prostate cancer were analyzed and their FTIR spectra were preprocessed for analysis. Characterization of morphology, particle size and marker proteins confirmed that EVs were successfully isolated from urine samples. Principal component analysis (PCA) of the EV's spectra showed the model could discriminate prostate cancer with a sensitivity of 59% and a specificity of 81%. The area under curve (AUC) of FTIR PCA model for prostate cancer detection in the cases with 4-20 ng/mL PSA was 0.7, while the AUC for PSA alone was 0.437, suggesting the analysis of urinary EVs described in this study may offer a novel strategy for the development of a noninvasive additional test for prostate cancer screening.
  20. Novel hormonal therapies in the management of advanced prostate cancer: extrapolating Asian findings to Southeast Asia
    Ong TA, Saad M, Lim J, Lee HH
    BMC Urol, 2023 Jan 06;23(1):4.
    PMID: 36609251 DOI: 10.1186/s12894-022-01156-8
    There is a paucity of information on the use of novel hormonal agents in Southeast Asian patients. We reviewed the clinical roles of novel hormonal therapy (NHT), namely abiraterone acetate (AA), enzalutamide, apalutamide and darolutamide, in the management of advanced prostate cancer, and data on its use in Asian patients, in order to extrapolate these findings to the Southeast Asian patient population. There are some differences in the molecular features between the NHTs, which influenced their respective permeabilities through the blood-brain barrier. The Asian sub-analyses of the landmark studies of each NHT were limited. The primary endpoints of the Asian sub-analyses generally reflect the efficacy outcomes of the respective landmark study. Hypertension, fatigue, musculoskeletal disorders, rash, and hot flushes were among the common toxicities observed in Asian patients. Real-world data on AA in the Asian setting is favourable, but data is limited for enzalutamide, apalutamide and darolutamide. Based on the sub-analyses and real-world data, the efficacy and safety of NHTs in the Asian patients showed a similar trend to the respective landmark studies. The lack of clinical trials in the Southeast Asian region hampers the ability to make a robust conclusion on any specific efficacy or safety differences that may be present; clinicians must assume that the broader Asian sub-analyses and real-world data reflects Southeast Asian patients' outcomes.
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