Displaying publications 21 - 40 of 61 in total

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  1. Kong NC, Shaariah W, Morad Z, Suleiman AB, Wong YH
    Aust N Z J Med, 1990 Oct;20(5):645-9.
    PMID: 2285381
    Cryptococcosis is a known opportunistic infection in immunosuppressed hosts. We report our experience of all cases presenting to our Department between December 1975 and September 1988. Eight post-renal transplant patients and three systemic lupus erythematosus (SLE) patients were affected. All were receiving treatment with steroids, in association with either azathioprine or cyclosporin. The diagnosis of cryptococcal meningitis was initially based on a positive cerebrospinal fluid (CSF) cryptococcal antigen, by latex agglutination test, and subsequently confirmed by cultures. Common clinical presentations, in descending order of frequency, included headaches, fever, mental confusion, epilepsy and papilloedema. Meningism was not a prominent feature. CT brain scans were obtained in eight patients and one showed a focal lesion and one showed cerebral atrophy. Four patients also had an abnormal chest X-ray (CXR) and one had disseminated cryptococcosis. Amphotericin and 5-fluorocytosine were the mainstay of therapy, although ketoconazole alone was subsequently used in three selected patients with cure. Four early deaths occurred in patients with delayed diagnosis and treatment, usually in association with other severe concurrent infections. We conclude that awareness of cryptococcosis is essential in immunocompromised hosts presenting with headache with, or without, mental confusion or fever.
  2. Arumugasamy N, Chin CS, Wong YH, Chew PH
    Aust N Z J Surg, 1985 Oct;55(5):517-8.
    PMID: 3868419
    A patient with a solitary intracranial cryptococcoma of the occipital lobe of the brain and a concomitant granuloma of similar aetiology in the breast is reported. Despite resistance of the causative fungus to 5-fluorocytosine in vitro, the patient responded well to radical excisional surgery and therapy with 5-fluorocytosine.
  3. Sindi R, Wong YH, Yeong CH, Sun Z
    Quant Imaging Med Surg, 2020 Jun;10(6):1237-1248.
    PMID: 32550133 DOI: 10.21037/qims-20-251
    Background: Despite increasing reports of 3D printing in medical applications, the use of 3D printing in breast imaging is limited, thus, personalized 3D-printed breast model could be a novel approach to overcome current limitations in utilizing breast magnetic resonance imaging (MRI) for quantitative assessment of breast density. The aim of this study is to develop a patient-specific 3D-printed breast phantom and to identify the most appropriate materials for simulating the MR imaging characteristics of fibroglandular and adipose tissues.

    Methods: A patient-specific 3D-printed breast model was generated using 3D-printing techniques for the construction of the hollow skin and fibroglandular region shells. Then, the T1 relaxation times of the five selected materials (agarose gel, silicone rubber with/without fish oil, silicone oil, and peanut oil) were measured on a 3T MRI system to determine the appropriate ones to represent the MR imaging characteristics of fibroglandular and adipose tissues. Results were then compared to the reference values of T1 relaxation times of the corresponding tissues: 1,324.42±167.63 and 449.27±26.09 ms, respectively. Finally, the materials that matched the T1 relaxation times of the respective tissues were used to fill the 3D-printed hollow breast shells.

    Results: The silicone and peanut oils were found to closely resemble the T1 relaxation times and imaging characteristics of these two tissues, which are 1,515.8±105.5 and 405.4±15.1 ms, respectively. The agarose gel with different concentrations, ranging from 0.5 to 2.5 wt%, was found to have the longest T1 relaxation times.

    Conclusions: A patient-specific 3D-printed breast phantom was successfully designed and constructed using silicone and peanut oils to simulate the MR imaging characteristics of fibroglandular and adipose tissues. The phantom can be used to investigate different MR breast imaging protocols for the quantitative assessment of breast density.

  4. Kameel NI, Wong YH, Shuib AS, Tayyab S
    Plant Physiol Biochem, 2016 Jan;98:57-63.
    PMID: 26642433 DOI: 10.1016/j.plaphy.2015.11.007
    Conformational analysis of champedak galactose-binding (CGB) lectin under different urea concentrations was studied in phosphate-buffered saline (pH 7.2) using far-ultraviolet circular dichroism (far-UV CD), tryptophan (Trp) fluorescence and ANS fluorescence. In all cases, CGB lectin displayed a two-step, three-state transition. The first transition (from the native state to the intermediate state) started at ∼2.0 M urea and ended at ∼4.5 M urea, while the second transition (from the intermediate state to the completely denatured state) was characterized by the start- and end-points at ∼5.75 M and ∼7.5 M urea, respectively, when analyzed by the emission maximum of Trp fluorescence. A marked increase in the Trp fluorescence, ANS fluorescence and -CD values at 218 nm (-CD218 nm) represented the first transition, whereas a decrease in these parameters defined the second transition. On the other hand, emission maximum of the Trp fluorescence showed a continuous increase throughout the urea concentration range. Transformation of tetramer into monomer represented the first transition, whereas the second transition reflected the unfolding of monomer. Far-UV CD, Trp fluorescence and ANS fluorescence spectra were used to characterize the native, the intermediate and the completely denatured states of CGB lectin, obtained at 0.0 M, 5.0 M and 9.0 M urea, respectively. The intermediate state was characterized by the presence of higher secondary structures, increased ANS binding as well as increased Trp fluorescence intensity. A gradual decrease in the hemagglutination activity of CGB lectin was observed with increasing urea concentrations, showing complete loss at 4.0 M urea.
  5. Nadia Ahmad NF, Nik Ghazali NN, Wong YH
    Biosens Bioelectron, 2021 May 30;189:113384.
    PMID: 34090154 DOI: 10.1016/j.bios.2021.113384
    The advanced stimuli-responsive approaches for on-demand drug delivery systems have received tremendous attention as they have great potential to be integrated with sensing and multi-functional electronics on a flexible and stretchable single platform (all-in-one concept) in order to develop skin-integration with close-loop sensation for personalized diagnostic and therapeutic application. The wearable patch pumps have evolved from reservoir-based to matrix patch and drug-in-adhesive (single-layer or multi-layer) type. In this review, we presented the basic requirements of an artificial pancreas, surveyed the design and technologies used in commercial patch pumps available on the market and provided general information about the latest wearable patch pump. We summarized the various advanced delivery strategies with their mechanisms that have been developed to date and representative examples. Mechanical, electrical, light, thermal, acoustic and glucose-responsive approaches on patch form have been successfully utilized in the controllable transdermal drug delivery manner. We highlighted key challenges associated with wearable transdermal delivery systems, their research direction and future development trends.
  6. Wong SK, Wong YH, Chin KY, Ima-Nirwana S
    Polymers (Basel), 2021 Sep 12;13(18).
    PMID: 34577976 DOI: 10.3390/polym13183075
    Calcium phosphate cement (CPC) is a promising material used in the treatment of bone defects due to its profitable features of self-setting capability, osteoconductivity, injectability, mouldability, and biocompatibility. However, the major limitations of CPC, such as the brittleness, lack of osteogenic property, and poor washout resistance, remain to be resolved. Thus, significant research effort has been committed to modify and reinforce CPC. The mixture of CPC with various biological materials, defined as the materials produced by living organisms, have been fabricated by researchers and their characteristics have been investigated in vitro and in vivo. This present review aimed to provide a comprehensive overview enabling the readers to compare the physical, mechanical, and biological properties of CPC upon the incorporation of different biological materials. By mixing the bone-related transcription factors, proteins, and/or polysaccharides with CPC, researchers have demonstrated that these combinations not only resolved the lack of mechanical strength and osteogenic effects of CPC but also further improve its own functional properties. However, exceptions were seen in CPC incorporated with certain proteins (such as elastin-like polypeptide and calcitonin gene-related peptide) as well as blood components. In conclusion, the addition of biological materials potentially improves CPC features, which vary depending on the types of materials embedded into it. The significant enhancement of CPC seen in vitro and in vivo requires further verification in human trials for its clinical application.
  7. Givehchi S, Wong YH, Yeong CH, Abdullah BJJ
    Minim Invasive Ther Allied Technol, 2018 Apr;27(2):81-89.
    PMID: 28612670 DOI: 10.1080/13645706.2017.1330757
    PURPOSE: To investigate the effect of radiofrequency ablation (RFA) electrode trajectory on complete tumor ablation using computational simulation.

    MATERIAL AND METHODS: The RFA of a spherical tumor of 2.0 cm diameter along with 0.5 cm clinical safety margin was simulated using Finite Element Analysis software. A total of 86 points inside one-eighth of the tumor volume along the axial, sagittal and coronal planes were selected as the target sites for electrode-tip placement. The angle of the electrode insertion in both craniocaudal and orbital planes ranged from -90° to +90° with 30° increment. The RFA electrode was simulated to pass through the target site at different angles in combination of both craniocaudal and orbital planes before being advanced to the edge of the tumor.

    RESULTS: Complete tumor ablation was observed whenever the electrode-tip penetrated through the epicenter of the tumor regardless of the angles of electrode insertion in both craniocaudal and orbital planes. Complete tumor ablation can also be achieved by placing the electrode-tip at several optimal sites and angles.

    CONCLUSIONS: Identification of the tumor epicenter on the central slice of the axial images is essential to enhance the success rate of complete tumor ablation during RFA procedures.

  8. Sun Z, Ng CKC, Wong YH, Yeong CH
    Biomolecules, 2021 09 03;11(9).
    PMID: 34572520 DOI: 10.3390/biom11091307
    The diagnostic value of coronary computed tomography angiography (CCTA) is significantly affected by high calcification in the coronary arteries owing to blooming artifacts limiting its accuracy in assessing the calcified plaques. This study aimed to simulate highly calcified plaques in 3D-printed coronary models. A combination of silicone + 32.8% calcium carbonate was found to produce 800 HU, representing extensive calcification. Six patient-specific coronary artery models were printed using the photosensitive polyurethane resin and a total of 22 calcified plaques with diameters ranging from 1 to 4 mm were inserted into different segments of these 3D-printed coronary models. The coronary models were scanned on a 192-slice CT scanner with 70 kV, pitch of 1.4, and slice thickness of 1 mm. Plaque attenuation was measured between 1100 and 1400 HU. Both maximum-intensity projection (MIP) and volume rendering (VR) images (wide and narrow window widths) were generated for measuring the diameters of these calcified plaques. An overestimation of plaque diameters was noticed on both MIP and VR images, with measurements on the MIP images close to those of the actual plaque sizes (<10% deviation), and a large measurement discrepancy observed on the VR images (up to 50% overestimation). This study proves the feasibility of simulating extensive calcification in coronary arteries using a 3D printing technique to develop calcified plaques and generate 3D-printed coronary models.
  9. Elhassan SA, Wong YH, Bhattamisra SK, Candasamy M
    Minerva Med, 2022 Oct;113(5):896-897.
    PMID: 32683846 DOI: 10.23736/S0026-4806.20.06611-2
  10. Wong YH, Kasbollah A, Abdullah BJJ, Yeong CH
    Pharmaceutics, 2023 Mar 08;15(3).
    PMID: 36986738 DOI: 10.3390/pharmaceutics15030877
    Radioembolization shows great potential as a treatment for intermediate- and advanced-stage liver cancer. However, the choices of radioembolic agents are currently limited, and hence the treatment is relatively costly compared to other approaches. In this study, a facile preparation method was developed to produce samarium carbonate-polymethacrylate [152Sm2(CO3)3-PMA] microspheres as neutron activatable radioembolic microspheres for hepatic radioembolization. The developed microspheres emits both therapeutic beta and diagnostic gamma radiations for post-procedural imaging. The 152Sm2(CO3)3-PMA microspheres were produced from commercially available PMA microspheres through the in situ formation of 152Sm2(CO3)3 within the pores of the PMA microspheres. Physicochemical characterization, gamma spectrometry and radionuclide retention assay were performed to evaluate the performance and stability of the developed microspheres. The mean diameter of the developed microspheres was determined as 29.30 ± 0.18 µm. The scanning electron microscopic images show that the spherical and smooth morphology of the microspheres remained after neutron activation. The 153Sm was successful incorporated into the microspheres with no elemental and radionuclide impurities produced after neutron activation, as indicated by the energy dispersive X-ray analysis and gamma spectrometry. Fourier transform infrared spectroscopy confirmed that there was no alteration to the chemical groups of the microspheres after neutron activation. After 18 h of neutron activation, the microspheres produced an activity of 4.40 ± 0.08 GBq.g-1. The retention of 153Sm on the microspheres was greatly improved to greater than 98% over 120 h when compared to conventionally radiolabeling method at ~85%. The 153Sm2(CO3)3-PMA microspheres achieved suitable physicochemical properties as theragnostic agent for hepatic radioembolization and demonstrated high radionuclide purity and 153Sm retention efficiency in human blood plasma.
  11. Wong YH, Tan WY, Tan CP, Long K, Nyam KL
    Asian Pac J Trop Biomed, 2014 May;4(Suppl 1):S510-5.
    PMID: 25183141 DOI: 10.12980/APJTB.4.2014C1090
    To examine the cytotoxic properties of both the kenaf (Hibiscus cannabinus L.) seed extract and kenaf seed oil on human cervical cancer, human breast cancer, human colon cancer and human lung cancer cell lines.
  12. Agarwal P, Wong YH, Das Gupta E, Agarwal R, Livingstone BI, Ramamurthy S, et al.
    Cutan Ocul Toxicol, 2015;34(3):179-84.
    PMID: 25068998 DOI: 10.3109/15569527.2014.938751
    BACKGROUND: Hydroxychloroquine (HCQ) is widely used for long-term treatment of autoimmune diseases such as rheumatoid arthritis. However, its long-term use is known to be associated with visual changes due to retinal damage. Retinal damage associated with long-term HCQ therapy is preventable if the drug is discontinued early when the patients are still asymptomatic. In view of contrasting reports from previous studies, we investigated the association of prolonged HCQ therapy with retinal thickness in macular area.
    METHODS: This study included 48 patients on long-term HCQ therapy and 38 healthy controls. All subjects underwent examination for corrected visual acuity, fundus photography, visual fields and SD-OCT for retinal thickness.
    RESULTS: Visual acuity, visual fields, fundus photography and SD-OCT did not reveal changes consistent with diagnosis of established HCQ retinopathy in any of the subjects from HCQ group. Retinal thickness in central, parafoveal and perifoveal areas did not show significant differences between HCQ and control groups. However, we observed negative correlation between cumulative dose and retinal thickness in the parafoveal (p = 0.003) and perifoveal areas (p = 0.019) but not in the central area.
    CONCLUSIONS: Correlation of cumulative dose with retinal thickness in parafoveal and perifoveal areas and not the central area is in accordance with the late appearance of HCQ-induced bull's eye retinopathy. Hence screening of asymptomatic patients using OCT seems to be of great importance for early detection of retinal changes.
    KEYWORDS: Cumulative dose; OCT; hydroxychloroquine; retinal thickness
  13. Wong YH, Lau HW, Tan CP, Long K, Nyam KL
    ScientificWorldJournal, 2014;2014:789346.
    PMID: 24592184 DOI: 10.1155/2014/789346
    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β -carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract) and sinapic acid (1198.22 mg/100 g extract), which can be used as alternative antioxidants in the food industry.
  14. Patrick TH, Fong AY, Sebastian Y, Raman V, Wong YH, Sim KH
    Inform Health Soc Care, 2009 Jan;34(1):1-9.
    PMID: 19306194 DOI: 10.1080/17538150902773090
    Mining for medical data poses different challenges compared with mining other types of data. The wide range of imaging modalities of medical data leads to data integration and compatibility issues. The analysis of imaging modalities is further complicated by the different format and attributes used by the different imaging equipment by different vendors. Human factors such as interest of adapting data mining into diagnosis and planning process raised the difficulty of engaging the users into the development of a practical and useful data miner. Requirement engineering technique prototyping further enhanced the engagement of users towards the data-miner. Data from different equipment and different vendors are also merged for efficient data analysis and subsequently charting and reporting. We have also successfully engaged the medical doctors into believing the data miner's capability after they reviewed and walkthrough the prototype.
  15. Lim NL, Wong YH, Boo NY, Kasim MS, Chor CY
    Med J Malaysia, 1995 Mar;50(1):59-63.
    PMID: 7752978
    A survey was conducted to determine the rate, outcome, and culture and sensitivity patterns of bacteraemic infections in a large Neonatal Intensive Care Unit (NICU). Over a nine-month period, 136 episodes of infection occurred in 132 (6.9%) out of 1926 admissions. Early onset infection accounted for 35 episodes (25.7%) and was associated with a higher mortality rate compared to late onset infection (45.7% vs 23.8%, p < 0.02). Very low birthweight (VLBW) infants had significantly higher rates of infection (19.4% vs 5.3%, p < 0.001) and mortality (45.2% vs 23.3%, p < 0.02) compared to bigger babies. Gram negative bacilli accounted for 25 early and 90 late isolates while gram positive organisms accounted for 10 early and 16 late isolates. The two main organisms (Acinetobacter and Klebsiella) showed a 69.0 to 85.3% resistance to aminoglycosides and 3rd generation cephalosporins. Ten of 13 isolates of Staphylococcus epidermidis and 3 of 4 Staphylococcus aureus were methicillin resistant. Multiply resistant infections were a major problem in this NICU and efforts to eradicate them needed to be intensified.
  16. Lee EL, Haseeb ASMA, Basirun WJ, Wong YH, Sabri MFM, Low BY
    Sci Rep, 2021 Aug 03;11(1):15768.
    PMID: 34344974 DOI: 10.1038/s41598-021-95276-0
    The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br-) in the range of 10-6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br- concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br- concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br- are also suggested.
  17. Wong YH, Muhamad H, Abas F, Lai OM, Nyam KL, Tan CP
    Food Chem, 2017 Mar 15;219:126-130.
    PMID: 27765207 DOI: 10.1016/j.foodchem.2016.09.130
    The effects of frying duration, frying temperature and concentration of sodium chloride on the formation of 3-monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GEs) of refined, bleached and deodorized (RBD) palm olein during deep-fat frying (at 160°C and 180°C) of potato chips (0%, 1%, 3% and 5% NaCl) for 100min/d for five consecutive days in eight systems were compared in this study. All oil samples collected after each frying cycle were analyzed for 3-MCPD esters, GEs, free fatty acid (FFA) contents, specific extinction at 232 and 268 nm (K232 and K268), p-anisidine value (pAV), and fatty acid composition. The 3-MCPD ester trend was decreasing when the frying duration increased, whereas the trend was increasing when frying temperature and concentration of NaCl increased. The GEs trend was increasing when the frying temperature, frying duration and concentration of NaCl increased. All of the oil qualities were within the safety limit.
  18. Wong YH, Tan HY, Kasbollah A, Abdullah BJJ, Yeong CH
    Pharmaceutics, 2019 Nov 12;11(11).
    PMID: 31718079 DOI: 10.3390/pharmaceutics11110596
    INTRODUCTION: Transarterial radioembolization (TARE) has been proven as an effective treatment for unresectable liver tumor. In this study, neutron activated, 153Sm-labeled microspheres were developed as an alternative to 90Y-labeled microspheres for hepatic radioembolization. 153Sm has a theranostic advantage as it emits both therapeutic beta and diagnostic gamma radiations simultaneously, in comparison to the pure beta emitter, 90Y.

    METHODS: Negatively charged acrylic microspheres were labeled with 152Sm ions through electrostatic interactions. In another formulation, the Sm-labeled microsphere was treated with sodium carbonate solution to form the insoluble 152Sm carbonate (152SmC) salt within the porous structures of the microspheres. Both formulations were neutron-activated in a research reactor. Physicochemical characterization, gamma spectrometry, and radiolabel stability tests were carried out to study the performance and stability of the microspheres.

    RESULTS: The Sm- and SmC-labeled microspheres remained spherical and smooth, with a mean size of 35 µm before and after neutron activation. Fourier transform infrared (FTIR) spectroscopy indicated that the functional groups of the microspheres remained unaffected after neutron activation. The 153Sm- and 153SmC-labeled microspheres achieved activity of 2.53 ± 0.08 and 2.40 ± 0.13 GBq·g-1, respectively, immediate after 6 h neutron activation in the neutron flux of 2.0 × 1012 n·cm-2·s-1. Energy-dispersive X-ray (EDX) and gamma spectrometry showed that no elemental and radioactive impurities were present in the microspheres after neutron activation. The retention efficiency of 153Sm in the 153SmC-labeled microspheres was excellent (~99% in distilled water and saline; ~97% in human blood plasma), which was higher than the 153Sm-labeled microspheres (~95% and ~85%, respectively).

    CONCLUSION: 153SmC-labeled microspheres have demonstrated excellent properties for potential application as theranostic agents for hepatic radioembolization.

  19. Goh KM, Wong YH, Ang MY, Yeo SCM, Abas F, Lai OM, et al.
    Food Res Int, 2019 07;121:553-560.
    PMID: 31108780 DOI: 10.1016/j.foodres.2018.12.013
    The detection of 3- and 2-MCPD ester and glycidyl ester was transformed from selected ion monitoring (SIM) mode to multiple reaction monitoring (MRM) mode by gas chromatography triple quadrupole spectrometry. The derivatization process was adapted from AOCS method Cd 29a-13. The results showed that the coefficient of determination (R2) of all detected compounds obtained from both detection mode was comparable, which falls between 0.997 and 0.999. The limit of detection and quantification (LOD and LOQ) were improved in MRM mode as compared to SIM mode. In MRM mode, the LOD of 3- and 2-MCPD ester was achieved 0.01 mg/kg while the LOQ was 0.05 mg/kg. Besides, LOD and LOQ of glycidyl ester were 0.024 and 0.06 mg/kg respectively. A blank spiked with MCPD esters (0.03, 0.10 and 0.50 mg/kg) and GE (0.06, 0.24 and 1.20 mg/kg) were chosen for repeatability and recovery tests. MRM mode showed better repeatability in area ratio and recovery with relative standard deviation (RSD %) 
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