ORCID Profile
0000-0002-6353-0397
Current Organisation
Nanyang Technological University
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Publisher: Wiley
Date: 25-01-2022
Abstract: An optical redox ratio can potentially be used to report on the dynamics of cell and tissue metabolism and define altered metabolic conditions for different pathologies. While there are methods to measure the optical redox ratio, they are not particularly suited to real‐time in situ or in vivo analysis. Here, we have developed a fiber‐optic system to measure redox ratios in cells and tissues and two mathematical models to enable real‐time, in vivo redox measurements. The optical redox ratios in tissue explants are correlated directly with endogenous NADH/FAD fluorescence emissions. We apply the mathematical models to the two‐photon microscopy data and show consistent results. We also used our fiber‐optic system to measure redox in different tissues and show consistent results between the two models, hence demonstrating proof‐of‐principle. This innovative redox monitoring system will have practical applications for defining different metabolic disease states.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 09-2010
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.WATRES.2010.12.001
Abstract: Understanding the foulant deposition mechanism during crossflow filtration is critical in developing indices to predict fouling propensity of feed water for reverse osmosis (RO). Factors affecting the performance on different fouling indices such as MFI-UF constant pressure, MFI-UF constant flux and newly proposed fouling index, CFS-MFI(UF) were investigated. Crossflow S ler-Modified Fouling Index Ultrafiltration (CFS-MFI(UF)) utilises a typical crossflow unit to simulate the hydrodynamic conditions in the actual RO units followed by a dead-end unit to measure the fouling propensity of foulants. CFS-MFI(UF) was found sensitive to crossflow velocity. The crossflow velocity in the crossflow s ler unit influences the particle concentration and the particle size distribution in its permeate. CFS-MFI(UF) was also found sensitive to the permeate flux of both CFS and the dead-end cell. To closely simulate the hydrodynamic conditions of a crossflow RO unit, the flux used for CFS-MFI(UF) measurement was critical. The best option is to operate both the CFS and dead-end permeate flux at flux which is normally operated at industry RO units (∼20 L/m(2)h), but this would prolong the test duration excessively. In this study, the dead-end flux was accelerated by reducing the dead-end membrane area while maintaining the CFS permeate flux at 20 L/m(2)h. By doing so, a flux correction factor was investigated and applied to correlate the CFS-MFI(UF) measured at dead-end flux of 120 L/m(2)h to CFS-MFI(UF) measured at dead-end flux of 20 L/m(2)h for RO fouling rate prediction. Using this flux correction factor, the test duration of CFS-MFI(UF) can be shortened from 15 h to 2h.
Publisher: Elsevier BV
Date: 02-2016
Publisher: MDPI AG
Date: 29-11-2022
DOI: 10.3390/MEMBRANES12121209
Abstract: Seawater reverse osmosis (SWRO) is the most energy-efficient process for desalination to produce drinking water from seawater. However, its sustainability is still challenged by membrane fouling. Appropriate feed water quality is one of the crucial prerequisites for SWRO operation. In the current study, a ceramic adsorption filter (CAF), which was predominantly coated with an aluminum-based adsorbent (i.e., Alumina, Al2O3), was employed to enhance the pretreatment performance of SWRO. The fouling performance of SWRO pre-treated with a CAF was evaluated by feeding with real ultrafiltration (UF)-filtrated seawater collected from a seawater desalination R& D facility in Singapore. The flux decline profile showed that the presence of CAF after UF could mitigate around 10–30% of SWRO fouling. Based on the autopsy of the fouled SWRO membranes, it was observed that SWRO with CAF pre-treatment and daily regeneration could alleviate around 77.5% of Ca-induced inorganic fouling as well as 76% of lower biofouling. The present work highlights the potential of applying adsorption technology to enhance pre-treatment performance to extend the lifespan of SWRO membranes. Coupling the adsorbents on a ceramic filter should be a useful way to ease their implementation, i.e., inline adsorption and re-generation.
Publisher: American Chemical Society (ACS)
Date: 13-04-2017
DOI: 10.1021/ACS.JPROTEOME.6B01032
Abstract: The evolutionary conserved family of 14-3-3 proteins appears to have a role in integrating numerous intracellular pathways, including signal transduction, intracellular trafficking, and metabolism. However, little is known about how this interactive network might be affected by the direct abrogation of 14-3-3 function. The loss of Drosophila 14-3-3ε resulted in reduced survival of mutants during larval-to-adult transition, which is known to depend on an energy supply coming from the histolysis of fat body tissue. Here we report a differential proteomic analysis of larval fat body tissue at the onset of larval-to-adult transition, with the loss of 14-3-3ε resulting in the altered abundance of 16 proteins. These included proteins linked to protein biosynthesis, glycolysis, tricarboxylic acid cycle, and lipid metabolic pathways. The ecdysone receptor (EcR), which is responsible for initiating the larval-to-adult transition, colocalized with 14-3-3ε in wild-type fat body tissues. The altered protein abundance in 14-3-3ε mutant fat body tissue was associated with transcriptional deregulation of alcohol dehydrogenase, fat body protein 1, and lamin genes, which are known targets of the EcR. This study indicates that 14-3-3ε has a critical role in cellular metabolism involving either molecular crosstalk with the EcR or direct interaction with metabolic proteins.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.CHEMOSPHERE.2019.125569
Abstract: This study compared the performance of an anaerobic fluidized bed membrane bioreactor (AFMBR)-zeolite adsorption-reverse osmosis (RO) system and an anoxic-aerobic MBR-RO system for municipal wastewater reclamation. Both MBR-RO systems were operated in parallel with the same operating conditions. The results showed that the MBR systems achieved excellent organic removals (>95%) and the anoxic-aerobic MBR could also remove ∼57% of soluble total nitrogen. Compared to the aerobic MBR, the AFMBR displayed better membrane performance with less energy consumption, attributed to effective membrane scouring by liquid-fluidized GAC particles. Furthermore, a zeolite column was employed to remove ammonia in the AFMBR permeate, which ensured comparable organic and nitrogen levels in the feeds to RO units in the two processes. Although less organic substances and microbial cells were accumulated on the RO membrane fed with AFMBR-zeolite column effluent, its fouling rate (∼6.5 ± 2.2 bar/day) was significantly greater than that fed with anoxic-aerobic MBR permeate (∼1.1 ± 1.5 bar/day). This may be associated with more severe inorganic colloidal fouling on the RO membrane, illustrated by an electrical impedance spectroscopy fouling monitoring system.
Publisher: Elsevier BV
Date: 04-2013
Publisher: Elsevier BV
Date: 09-2023
Publisher: Wiley
Date: 05-08-2021
Abstract: Electrochemical impedance spectroscopy (EIS), one of the techniques for electrochemical analysis, has been used for a wide range of applications especially chemical‐ and bio‐sensing. Besides, EIS is one of the few techniques that has been proven useful for membrane fouling detection. Electrodes are some of the most essential components for analytes detection applications with EIS. With the advances in printing technology, the fabrication of advanced printed electrode systems with miniature designs and improved sensitivity for electrochemical sensing is made possible. This review addresses recent advances in printed electrodes for electrochemical impedance spectroscopy with the emphasis placed on discussing the use of printed electrodes for membrane fouling detection. Common electrode designs and materials for electrochemical impedance spectroscopy are discussed, along with practical ex les of these printed electrodes. The commonly used printing techniques for the fabrication of printed electrodes are also deliberated. The successful realization of printed electrodes for EIS requires careful design of electrodes, proper selection of electrode materials, as well as optimization of the printing process. It is expected that printed electrodes will be widely accepted for EIS sensing applications and will facilitate the creation of low‐cost high‐performance sensing devices.
Publisher: Wiley
Date: 28-11-2018
Abstract: The heart has high metabolic demand to maintain function. The primary source of energy supply to support correct contractile muscle function differs between a fetus and an adult. In fetal life, ATP is primarily generated by glycolysis and lactate oxidation, whereas following birth, there is a shift towards a reliance on mitochondrial metabolism and fatty acid oxidation. This change in metabolic status is an adaptation to different fuel availability, oxygenation and growth patterns. In this study, we have employed 2-photon excitation fluorescence microscopy to define the relationship between two critical metabolic cofactors nicotinamide adenine dinucleotide(P)H and flavin adenine dinucleotide, effectively utilizing a redox ratio to differentiate between the metabolic status in fetal (proliferative) and adult (quiescent/hypertrophic) hearts. Two-photon imaging was also used to visually confirm the known increase in collagen deposition in the adult heart. The changes observed were consistent with a hypertrophic growth profile and greater availability of fatty acids in the adult heart, compared to the proliferative fetal heart. Two-photon excitation fluorescence microscopy is therefore a convenient imaging technology that enables the monitoring of striated muscle architecture and the metabolic status of heart tissue. This imaging technology can potentially be employed to visualize cardiac and other muscle pathologies.
Publisher: MDPI AG
Date: 27-01-2023
Abstract: The extracellular matrix (ECM) is the complex three-dimensional network of fibrous proteins and proteoglycans that constitutes an essential part of every tissue to provide support for normal tissue homeostasis. Tissue specificity of the ECM in its topology and structure supports unique biochemical and mechanical properties of each organ. Cancers, like normal tissues, require the ECM to maintain multiple processes governing tumor development, progression and spread. A large body of experimental and clinical evidence has now accumulated to demonstrate essential roles of numerous ECM components in all cancer types. Latest findings also suggest that multiple tumor types express, and use to their advantage, atypical ECM components that are not found in the cancer tissue of origin. However, the understanding of cancer-specific expression patterns of these ECM proteins and their exact roles in selected tumor types is still sketchy. In this review, we summarize the latest data on the aberrant expression of bone and cartilage ECM proteins in epithelial cancers and their specific functions in the pathogenesis of carcinomas and discuss future directions in exploring the utility of this selective group of ECM components as future drug targets.
Publisher: MDPI AG
Date: 05-02-2020
DOI: 10.3390/CELLS9020372
Abstract: Innate immunity is critical for host defence against pathogen and environmental challenge and this involves the production and secretion of immune mediators, such as antimicrobial peptides and pro-inflammatory cytokines. However, when dysregulated, innate immunity can contribute to multifactorial diseases, including inflammatory rheumatic disorders, type 2 diabetes, cancer, neurodegenerative and cardiovascular diseases and even septic shock. During an innate immune response, antimicrobial peptides and cytokines are trafficked via Rab11 multivesicular endosomes, and then sorted into Rab11 vesicles for traffic to the plasma membrane and secretion. In this study, a cyclin-dependent kinase inhibitor CDKI-73 was used to determine its effect on the innate immune response, based on previously identified targets for this compound. Our results showed that CDKI-73 inhibited the delivery of Rab11 vesicles to the plasma membrane, resulting in the accumulation of large multivesicular Rab11 endosomes near the cell periphery. In addition to the effect on endosome delivery, CDKI-73 down-regulated the amount of innate immune cargo, including the antimicrobial peptide Drosomycin and pro-inflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFα). We concluded that CDKI-73 has the potential to regulate the delivery and secretion of certain innate immune cargo, which could be used to control inflammation.
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 05-2018
Publisher: Wiley
Date: 23-12-2020
Abstract: The primary metabolic pathway required to produce ATP differs as a result of tissue type, developmental stage and substrate availability. We utilized molecular and histological techniques to define the metabolic status in foetal and adult, adipose and skeletal muscle tissues. Redox ratios of these tissues were also determined optically by two-photon microscopy. Adult perirenal adipose tissue had a higher optical redox ratio than fetal perirenal adipose tissue, which aligned with glycolysis being used for ATP production whereas adult skeletal muscle had a lower optical redox ratio than fetal skeletal muscle, which aligned with oxygen demanding oxidative phosphorylation activity being utilized for ATP production. We have compared traditional molecular and microscopy techniques of metabolic tissue characterization with optical redox ratios to provide a more comprehensive report on the dynamics of tissue metabolism.
Publisher: Elsevier BV
Date: 02-2021
Publisher: MDPI AG
Date: 16-06-2023
Abstract: Gleason scoring is used within a five-tier risk stratification system to guide therapeutic decisions for patients with prostate cancer. This study aimed to compare the predictive performance of routine H& E or biomarker-assisted ISUP (International Society of Urological Pathology) grade grouping for assessing the risk of biochemical recurrence (BCR) and clinical recurrence (CR) in patients with prostate cancer. This retrospective study was an assessment of 114 men with prostate cancer who provided radical prostatectomy s les to the Australian Prostate Cancer Bioresource between 2006 and 2014. The prediction of CR was the primary outcome (median time to CR 79.8 months), and BCR was assessed as a secondary outcome (median time to BCR 41.7 months). The associations of (1) H& E ISUP grade groups and (2) modified ISUP grade groups informed by the Appl1, Sortilin and Syndecan-1 immunohistochemistry (IHC) labelling were modelled with BCR and CR using Cox proportional hazard approaches. IHC-assisted grading was more predictive than H& E for BCR (C-statistic 0.63 vs. 0.59) and CR (C-statistic 0.71 vs. 0.66). On adjusted analysis, IHC-assisted ISUP grading was independently associated with both outcome measures. IHC-assisted ISUP grading using the biomarker panel was an independent predictor of in idual BCR and CR. Prospective studies are needed to further validate this biomarker technology and to define BCR and CR associations in real-world cohorts.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 12-2021
Publisher: MDPI AG
Date: 23-12-2021
Abstract: Fluorescence microscopy has become a critical tool for researchers to understand biological processes at the cellular level. Micrographs from fixed and live-cell imaging procedures feature in a plethora of scientific articles for the field of cell biology, but the complexities of fluorescence microscopy as an imaging tool can sometimes be overlooked or misunderstood. This review seeks to cover the three fundamental considerations when designing fluorescence microscopy experiments: (1) hardware availability (2) amenability of biological models to fluorescence microscopy and (3) suitability of imaging agents for intended applications. This review will help equip the reader to make judicious decisions when designing fluorescence microscopy experiments that deliver high-resolution and informative images for cell biology.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Wiley
Date: 10-01-2021
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 02-2015
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.CHEMOSPHERE.2018.12.066
Abstract: The presence of transparent exopolymer particles (TEP) in water bodies has been related to several adverse impacts in various water treatment processes. In recent years, there have been an increasing number of publications relating to TEP. Unfortunately, this increased interest in TEP measurement has not been accompanied by significant improvement in the analysis method or TEP monitoring. Currently, the most common method to analyze and quantify TEP only allows offline, and often offsite measurement, causing delays and slow response times. This paper introduces an improved method for TEP monitoring using a membrane-based spectrophotometric technique to quantify TEP in various water bodies. The proposed TEP monitor involves a crossflow filtration unit, reagent injection and a spectrophotometer system. The TEP retained on the membrane surface is stained by Alcian blue and the amount deposited is quantified directly using an optic fibre reflectance probe coupled with a spectrophotometer. The novel method shows a linear relationship with various concentrations of Xanthan gum (a model representing TEP). When tested with various water s les, the proposed method was found to correlate well with the conventional method. Several advantages of this novel method are shorter analysis time, increased accuracy, and the potential to be further developed into an online system.
Publisher: Elsevier BV
Date: 04-2019
Publisher: American Chemical Society (ACS)
Date: 07-2021
Publisher: Elsevier BV
Date: 12-2013
No related grants have been discovered for Lee Nuang Sim.