Displaying publications 1 - 20 of 61 in total

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  1. Fulltext 3D visualization and 3D printing in abnormal gastrointestinal system manifestations of situs ambiguus
    Etherton D, Tee L, Tillett C, Wong YH, Yeong CH, Sun Z
    Quant Imaging Med Surg, 2020 Sep;10(9):1877-1883.
    PMID: 32879864 DOI: 10.21037/qims-20-661
  2. Fulltext 3D-Printed Coronary Plaques to Simulate High Calcification in the Coronary Arteries for Investigation of Blooming Artifacts
    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.
  3. Fulltext 5-Fluorocytosine resistance in clinical isolates of Cryptococcus neoformans
    Chin CS, Cheong YM, Wong YH
    Med J Malaysia, 1989 Sep;44(3):194-8.
    PMID: 2696871
    Thirty six clinical isolates of Cryptococcus neoformans were tested for their susceptibility to 5-fluorocytosine and amphotericin B by the determination of minimum inhibitory concentrations and minimum fungicidal concentrations. 22.2% of the isolates were resistant to 5-fluorocytosine and 36.1% indicated 5-fluorocytosine tolerance. All strains were sensitive to amphotericin B.
  4. A Comparative Analysis of Protein Stabilizing Potential of Honey and Simulated Honey Sugar Cocktail
    Wong YH, Kadir HA, Tayyab S
    Protein Pept Lett, 2016;23(10):898-904.
    PMID: 27586182
    Urea and thermal denaturations of bovine serum albumin (BSA) were studied in the absence and the presence of honey or simulated honey sugar cocktail (SHSC) using far-UV CD and ANS fluorescence spectroscopy. Presence of 20% (w/v) honey or SHSC in the incubation mixture shifted the urea transition curve towards higher urea concentrations, being higher in the presence of honey and transformed the two-step, three-state transition into a single-step, two-state transition. A comparison of the far-UV CD and the ANS fluorescence spectra of 4.6 M urea-denatured BSA (U-BSA) in the absence and the presence of 20% (w/v) honey or SHSC suggested greater stabilizing potential of honey than SHSC, as U-BSA maintained native like conformation in the presence of 20% (w/v) honey. Furthermore, thermal transition curves of BSA were also shifted towards higher temperature range in the presence of 20% (w/v) SHSC and honey, showing greater shift in the presence of honey. The far-UV CD spectra of the heat-denatured BSA also showed greater stabilization in the presence of honey. Taken together all these results suggested greater protein stabilizing potential of honey than SHSC against chemical and thermal denaturations of BSA.
  5. Fulltext A Review on the Enhancement of Calcium Phosphate Cement with Biological Materials in Bone Defect Healing
    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.
  6. Fulltext A Systematic Review of Molecular Hydrogen Therapy in Cancer Management
    Mohd Noor MNZ, Alauddin AS, Wong YH, Looi CY, Wong EH, Madhavan P, et al.
    Asian Pac J Cancer Prev, 2023 Jan 01;24(1):37-47.
    PMID: 36708550 DOI: 10.31557/APJCP.2023.24.1.37
    BACKGROUND: Cancer remains a challenging target to cure, with present therapeutic methods unable to exhibit restorative outcomes without causing severe negative effects. Molecular hydrogen (H2) has been reported to be a promising adjunctive therapy for cancer treatment, having the capability to induce anti-proliferative, anti-oxidative, pro-apoptotic and anti-tumoural effects. This review summarises the findings from various articles on the mechanism, treatment outcomes, and overall effectiveness of H2 therapy on cancer management.

    METHODS: Using Cochrane, PubMed, and Google Scholar as the search engines, full-text articles in the scope of the study, written in English and within 10 years of publication were selected.

    RESULTS: Out of the 677 articles, 27 articles fulfilled the eligibility criteria, where data was compiled into a table, outlining the general characteristics and findings. Throughout the different forms of H2 administration, study design and types of cancers reported, outcomes were found to be consistent.

    CONCLUSION: From our analysis, H2 plays a promising therapeutic role as an independent therapy as well as an adjuvant in combination therapy, resulting in an overall improvement in survivability, quality of life, blood parameters, and tumour reduction. Although more comprehensive research is needed, given the promising outcomes, H2 is worth considering for use as a complement to current cancer therapy.

  7. Fulltext A one year community-based study on the incidence of diarrhoea and rotavirus infection in urban and suburban Malaysian children
    Yap KL, Yasmin AM, Wong YH, Ooi YE, Tan SC, Jegathesan M, et al.
    Med J Malaysia, 1992 Dec;47(4):303-8.
    PMID: 1303484
    A 1 year longitudinal study of 156 Malaysian children from urban and suburban areas in the Klang Valley revealed that the incidence rate of diarrhoea was 23.6 per 100 person-year with abnormal faeces reported on 0.26% of the total days of observation. Diarrhoea cases were detected in children from all socioeconomic classes. Rotavirus was isolated from 12% of the diarrheic children and asymptomatic rotavirus infection occurred in 3.2% of the children. All rotaviruses isolated were group A rotaviruses with long electrophoretypic pattern.
  8. Antibiotic susceptibility and serotype distribution of Streptococcus pneumoniae in Malaysian children
    Cheong YM, Jegathesan M, Henrichsen J, Wong YH, Ng AJ, Louis A
    J Trop Pediatr, 1988 08;34(4):182-5.
    PMID: 3172328 DOI: 10.1093/tropej/34.4.182
  9. Fulltext Bacteraemic infections in a neonatal intensive care unit--a nine-month survey
    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.
  10. Fulltext Band alignment and enhanced breakdown field of simultaneously oxidized and nitrided Zr film on Si
    Wong YH, Cheong KY
    Nanoscale Res Lett, 2011;6:489.
    PMID: 21831264 DOI: 10.1186/1556-276X-6-489
    The band alignment of ZrO2/interfacial layer/Si structure fabricated by simultaneous oxidation and nitridation of sputtered Zr on Si in N2O at 700°C for different durations has been established by using X-ray photoelectron spectroscopy. Valence band offset of ZrO2/Si was found to be 4.75 eV, while the highest corresponding conduction offset of ZrO2/interfacial layer was found to be 3.40 eV; owing to the combination of relatively larger bandgaps, it enhanced electrical breakdown field to 13.6 MV/cm at 10-6 A/cm2.
  11. Fulltext Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction
    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.
  12. Fulltext Bioassay-Guided Isolation of Cytotoxic Cycloartane Triterpenoid Glycosides from the Traditionally Used Medicinal Plant Leea indica
    Wong YH, Abdul Kadir H, Ling SK
    Evid Based Complement Alternat Med, 2012;2012:164689.
    PMID: 22203865 DOI: 10.1155/2012/164689
    Leea indica is a medicinal plant used traditionally to cure cancer. In this study, the cytotoxic compounds of L. indica were isolated using bioassay-guided approach. Two cycloartane triterpenoid glycosides, mollic acid arabinoside (MAA) and mollic acid xyloside (MAX), were firstly isolated from L. indica. They inhibited the growth of Ca Ski cervical cancer cells with IC(50) of 19.21 μM (MAA) and 33.33 μM (MAX). MRC5 normal cell line was used to calculate selectivity index. MAA and MAX were about 8 and 4 times more cytotoxic to Ca Ski cells compared to MRC5. The cytotoxicity of MAA was characterized by both cytostatic and cytocidal effects. MAA decreased the expression of proliferative cell nuclear antigen, increased sub-G1 cells, and arrested cells in S and G2/M phases. This study provides the evidence for the ethnomedicinal use of L. indica and paves the way for future mechanism studies on the anticancer effects of MAA.
  13. Fulltext Campylobacter jejuni as a cause of diarrhoea in Kuala Lumpur, Malaysia
    Lim YS, Jegathesan M, Wong YH
    Med J Malaysia, 1984 Dec;39(4):285-8.
    PMID: 6544934
    The incidence of Campylobacter jejuni in patients with and without diarrhoea was studied in Kuala Lumpur, Malaysia. C. jejuni was recovered from 3.8% and 4.3% of diarrhoeal stools of children and adults, respectively. From the patients without diarrhoea, the relative isolation rates for children and adults were 2.6% and 0%, respectively. Dual infections occurred in two children, with Salmonella and enteropathogenic Escherichia coli being the other enteric pathogen in each case. Cary-Blair medium was found to be an effective transport medium in recovering C. jejuni. Campylobacter enteritis occurred in patients of various age groups, indicating that this organism should be sought routinely by diagnostic laboratories in faecal specimens from patients with diarrhoea.
  14. Cardiovascular diagnostics mining on Borneo island: from labour-intensive to prototype
    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. Fulltext Changes in 3-, 2-Monochloropropandiol and Glycidyl Esters during a Conventional Baking System with Addition of Antioxidants
    Goh KM, Wong YH, Abas F, Lai OM, Mat Yusoff M, Tan TB, et al.
    Foods, 2020 Jun 04;9(6).
    PMID: 32512737 DOI: 10.3390/foods9060739
    Shortening derived from palm oil is widely used in baking applications. However, palm oil and the related products are reported to contain high levels of monochloropropandiol (MCPD) ester and glycidyl ester (GE). MCPD and glycidol are known as process contaminants, which are carcinogenic and genotoxic compounds, respectively. The objective was to evaluate the effects of antioxidant addition in palm olein and stearin to the content of MCPD esters and GE in baked cake. Butylated hydroxyanisole (BHA), rosemary extract and tocopherol were used to fortify the samples at 200 mg/kg and in combinations (400, 600 and 800 mg/kg rosemary or tocopherol combined with 200 mg/kg BHA). The MCPD esters and GE content, radical formation and the quality of the fats portion were analyzed. The results showed that palm olein fortified with rosemary extract yielded less 2-MCPD ester. The GE content was lower when soft stearin was fortified with rosemary. ESR spectrometry measurements showed that the antioxidants were effective to reduce radical formation. The synergistic effects of combining antioxidants controlled the contaminants formation. In conclusion, oxidation stability was comparable either in the single or combined antioxidants. Tocopherol in combination with BHA was more effective in controlling the MCPD esters and GE formation.
  16. Comparison assessment between SIM and MRM mode in the analysis of 3-MCPD ester, 2-MCPD ester and glycidyl ester
    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 %) 
  17. Concomitant cerebral and breast cryptococcosis
    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.
  18. Conformational analysis of champedak galactose-binding lectin under different urea concentrations
    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.
  19. Conjugal transfer of multiple antibiotic resistance from hospital isolates of Klebsiella to Escherichia coli
    Koh CL, Lim ME, Wong YH
    Southeast Asian J. Trop. Med. Public Health, 1983 Sep;14(3):336-40.
    PMID: 6362015
    Six independent isolates of Klebsiella from hospital environmental sources in Malaysia were found to be resistant to at least ampicillin, carbenicillin, cefoperazone, chloramphenicol, gentamicin and tetracycline. On the basis of their antibiograms, they were divided into four antibiogroups. They transferred all or part of their multiple antibiotic resistance traits to E. coli by conjugation. The results suggest that these Klebsiella strains harbour self-transmissible R plasmids. The significance of these findings are discussed.
  20. Cryptococcosis in a renal unit
    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.
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