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  1. Fulltext Coronary artery spasm (CAS) simulating inferior ST elevation myocardial infarction (STEMI)
    Liew CK, Leong WS
    Med J Malaysia, 2012 Feb;67(1):108-10.
    PMID: 22582559 MyJurnal
    Coronary arteries vasospasm (CAS) is commonly seen in invasive cardiology laboratory during diagnostic catheterization or coronary intervention. Though the incidence of Printzmetal angina is uncommon, coronary vasospasm resulting in acute myocardial infarct is rare, especially if there is no significant atherosclerotic plaque within the coronary vasculature.
  2. Fulltext Navigating new product development: Uncovering factors and overcoming challenges for success
    Falahat M, Chong SC, Liew C
    Heliyon, 2024 Jan 15;10(1):e23763.
    PMID: 38226274 DOI: 10.1016/j.heliyon.2023.e23763
    New product development (NPD) frequently encounters failures, whether during the development phase or in the subsequent commercialization stage. These failures can often be attributed to root causes originating in the early stages of NPD, known as the front end. This study aims to investigate the factors that contribute to NPD success and the challenges faced by firms throughout the development process. To achieve this objective, an in-depth qualitative approach utilizing interviews was employed to explore the internal and external factors influencing NPD success. Additionally, the study aims to identify specific challenges encountered by firms during the NPD process. The identification of these factors and challenges are crucial for companies as it can lead to long-term cost savings. The findings of this study have broad implications for firms regardless of their product plans. By adopting the derived approach, companies can effectively navigate the product development process and gain insights into the potential challenges associated with introducing a new product into an existing market. As customer preferences evolve with technological advancements, the barriers and challenges faced by new products entering established markets also increase. Therefore, firms that incorporate the results of this study into their product development practices across various industries can avoid pitfalls and achieve greater efficiency in terms of time and costs. This research sheds light on critical areas that contribute to successful product development and provides valuable guidance for firms striving to excel in their NPD endeavors.
  3. Lignin biodegradation and ligninolytic enzyme studies during biopulping of Acacia mangium wood chips by tropical white rot fungi
    Liew CY, Husaini A, Hussain H, Muid S, Liew KC, Roslan HA
    World J Microbiol Biotechnol, 2011 Jun;27(6):1457-68.
    PMID: 25187145 DOI: 10.1007/s11274-010-0598-x
    White rot fungi are good lignin degraders and have the potential to be used in industry. In the present work, Phellinus sp., Daedalea sp., Trametes versicolor and Pycnoporus coccineus were selected due to their relatively high ligninolytic enzyme activity, and grown on Acacia mangium wood chips under solid state fermentation. Results obtained showed that manganese peroxidase produced is far more compared to lignin peroxidase, suggesting that MnP might be the predominating enzymes causing lignin degradation in Acacia mangium wood chips. Cellulase enzyme assays showed that no significant cellulase activity was detected in the enzyme preparation of T. versicolor and Phellinus sp. This low cellulolytic activity further suggests that these two white rot strains are of more interest in lignin degradation. The results on lignin losses showed 20-30% of lignin breakdown at 60 days of biodegradation. The highest lignin loss was found in Acacia mangium biotreated with T. versicolor after 60 days and recorded 26.9%, corresponding to the percentage of their wood weight loss recorded followed by P. coccineus. In general, lignin degradation was only significant from 20 days onwards. The overall percentage of lignin weight loss was within the range of 1.02-26.90% over the biodegradation periods. Microscopic observations conducted using scanning electron microscope showed that T. versicolor, P. coccineus, Daedalea sp. and Phellinus sp. had caused lignin degradation in Acacia mangium wood chips.
  4. Fulltext Durian induced hyperkalaemia
    Leo CL, Leong WS, Tieh CS, Liew CK
    Med J Malaysia, 2011 Mar;66(1):66-7.
    PMID: 23765149 MyJurnal
    Hyperkalaemia is a life threatening acute medical emergency. Patients with end stage renal failure are more prone to get hyperkalaemia as potassium is normally excreted via the kidneys. Therefore, patients with end stage renal failure should avoid food with high potassium contents. Bananas are well known to have high potassium content. However, the 'king of fruits' the durian, has higher potassium content compared to bananas. We describe a case of life threatening hyperkalaemia in a lady with end stage renal failure who ate durians prior to her presentation.
  5. Cochlear duct length-one size fits all?
    Thong JF, Low D, Tham A, Liew C, Tan TY, Yuen HW
    Am J Otolaryngol, 2017 Mar-Apr;38(2):218-221.
    PMID: 28139318 DOI: 10.1016/j.amjoto.2017.01.015
    OBJECTIVE: Recent studies demonstrated the utility of high-resolution computed tomography (HRCT) scans in measuring basal cochlear length and cochlear insertion depths. These studies showed significant variations in the anatomy of the cochlea amongst humans. The aim of our study was to investigate for gender and racial variations in the basal turn length of the human cochlea in an Asian population.

    METHOD: HRCT temporal bone data from year 1997 till 2012 of patients with normally developed cochleae who reported with otologic disease was obtained. Reconstruction of the full basal turn was performed for both ears. The largest distance from the midpoint of the round window, through the midmodiolar axis, to the lateral wall was measured (distance A). Length of the lateral wall of the cochlea to the first turn (360°) was calculated and statistically analyzed.

    RESULTS: HRCT temporal bone data from 161 patients was initially obtained. Four patients were subsequently excluded from the study as they were of various other racial groups. Study group therefore comprised of 157 patients (314 cochleae). Mean distance A was statistically different between the two sides of the ear (right 9.09mm; left 9.06mm; p=0.0069). Significant gender and racial differences were also found. Mean distance A was 9.17mm in males and 8.97mm in females (p=0.0016). The racial groups were Chinese (39%), Malay (38%) and Indian (22%). Between racial groups, mean distance A was 9.11mm (Chinese), 9.11mm (Malays) and 8.99mm (Indians). The mean basal turn lengths ranged from 19.71mm to 25.09mm. With gender factored in, significant variation in mean basal turn lengths was found across all three racial groups (p=0.04).

    CONCLUSION: The view of the basal turn of the cochlea from HRCT is simple to obtain and reproducible. This study found significant differences in basal cochlear length amongst male and female Asian patients, as well as amongst various racial groups. This has implications for cochlear electrode insertion as well as electrode array design.
  6. Fulltext Dual blockade of the renin-angiotensin-aldosterone system is safe and effective in reducing albuminuria in Asian type 2 diabetic patients with nephropathy
    Tan F, Mukherjee JJ, Lee KO, Lim P, Liew CF
    Singapore Med J, 2010 Feb;51(2):151-6.
    PMID: 20358155
    INTRODUCTION: Blockade of the renin-angiotensin-aldosterone system (RAAS) by either the angiotensin converting enzyme inhibitor (ACE-I) or the angiotensin II receptor blocker (ARB) has been shown to reduce albuminuria and delay the progression of diabetic nephropathy. This study evaluated the effect of dual blockade of the RAAS by adding an ACEI or an ARB to the administration of either drug alone on albuminuria in Asian type 2 diabetic patients with nephropathy.
    METHODS: 34 patients were randomly assigned to receive either enalapril 20 mg or losartan 100 mg once daily for eight weeks. Following this, all patients received a combination of enalapril 10 mg and losartan 50 mg daily for eight weeks, followed by enalapril 20 mg and losartan 100 mg daily for another eight weeks. The blood pressure and 24-hour urinary albumin excretion (UAE) were monitored.
    RESULTS: Following monotherapy with enalapril, there was a mean and standard error (SE) reduction in the UAE and mean arterial pressure (MAP) of 9.8 (SE 6.8) percent (p-value is 0.061) and 5.3 (SE 2.2) mmHg (p-value is 0.026), respectively; the reduction in UAE and MAP following monotherapy with losartan was by 10.9 (SE 14.1) percent (p-value is 0.053) and 4.5 (SE 1.9) mmHg (p-value is 0.034), respectively. Combination therapy with enalapril and losartan further reduced the UAE (11.2 [SE 8.7] percent, p-value is 0.009] despite there being no significant change in the MAP (-1.2 [SE 1.47] mmHg, p-value is 0.42). The adverse effects included dry cough (seven [19.4 percent] patients, resulting in the withdrawal of medication in two patients), and transient hyperkalaemia (two [six percent] patients).
    CONCLUSION: Dual blockade of the RAAS is safe and effective in reducing albuminuria in Asian type 2 diabetic patients with nephropathy.
  7. Fulltext Feasibility and accuracy of 64-row MDCT coronary imaging from a centre with early experience: a review and comparison with established centres
    Ong TK, Chin SP, Chan WL, Liew CK, Seyfarth MT, Liew HB, et al.
    Med J Malaysia, 2005 Dec;60(5):629-36.
    PMID: 16515115
    The accuracy of multi-detector computed tomographic (MDCI) coronary angiography (CTA) is dependant on image quality as well as the experience of the operator. Established centers have reported negative predictive values of over 95%. The aim of our study was to investigate the accuracy and feasibility of CTA for the assessment of haemodynamically significant coronary stenosis in a center with very early experience (<6 months) utilizing the improved spatial and temporal resolutions of the latest generation 64-row MDCI scanner. One hundred and twenty eight patients (93 male, 35 female; mean age 56.2 +/- 9.5 years) with suspected or known coronary artery disease underwent both CIA and conventional coronary angiographv (CCA). The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values for stenoses > or =50% by CIA compared to CCA were 70%, 97%, 70% and 97% respectively. Evaluation of main and proximal segments in patients with good quality images (78% of patients) produced values of 94%, 95%, 74% and 99% respectively. The improved spatial and temporal resolutions of 64-row MJ) CT provided a high negative predictive value in assessing significant coronary artery stenosis even in a centre with very early experience. However, new centers embarking on CTA might not be able to reproduce the results reported by more experienced centers.
  8. Fulltext New mosquito species records (Diptera: Culicidae) from Singapore
    Jeffery J, Lee RM, Tan SY, Liew C, Ng LC, Lam-Phua SG
    Trop Biomed, 2010 Apr;27(1):138-42.
    PMID: 20562825
    Nine species of mosquitoes in eight genera are recorded for the first time in Singapore. An additional two species were overlooked in a 1986 checklist for mosquitoes in Singapore, and one was described after 1986. Location and habitat data are provided for the nine new records. With the inclusion of these new records the number of species reported from Singapore is 137.
  9. Prognosis of oral epithelial dysplasia in individuals with and without oral lichen planus
    Pimolbutr K, Lim WT, Leeson R, Hopper C, Kalavrezos N, Liew C, et al.
    Oral Dis, 2024 Mar;30(2):504-517.
    PMID: 36648368 DOI: 10.1111/odi.14503
    OBJECTIVES: To investigate the role of oral lichen planus (OLP) on the long-term prognosis of oral epithelial dysplasia (OED).

    METHODS: Retrospective single-centre cohort study using the 2007-2019 database of the Head and Neck Cancer and Oral Medicine units of University College London Hospital. The exposure of interest was the presence of OLP, and the prognostic outcomes included the development of new primary episodes of OED, progression to malignancy and mortality. Cox proportional hazard and Poisson regression models were performed.

    RESULTS: A total of 299 patients, of whom 144 had OED arising on the background of OLP (OLP/OED) and 155 had OED without underlying OLP (non-OLP/OED), were included. A pre-existing diagnosis of OLP was significantly associated with a twofold increased risk of subsequent primary OED events (HR = 2.02, p = 0.04), which also developed faster (1.46 vs. 2.96 years, p = 0.04) and with more involvement of non-cancer-prone sites (p = 0.001) than in the non-OLP/OED group. There was no difference between groups in the progression to malignancy or mortality.

    CONCLUSIONS: Oral lichen planus/OED patients are at higher risk of multiple episodes of primary OED, which can develop faster and at non-cancer-prone sites as compared to non-OLP/OED individuals. Further research is needed to clarify the effects of OLP upon progression to OSCC and mortality.

  10. Fulltext Mosquitoes (Diptera: Culicidae) of Singapore: Updated Checklist and New Records
    Lam-Phua SG, Yeo H, Lee RM, Chong CS, Png AB, Foo SY, et al.
    J Med Entomol, 2019 Jan 08;56(1):103-119.
    PMID: 30169704 DOI: 10.1093/jme/tjy154
    Prior to 1965, Singapore was part of the Malaya (now Malaysia) and was usually not mentioned when mosquito records were reported for Malaya. Consequently, many species that occurred in Singapore were not listed in the world mosquito catalog, and the available checklist for Singapore since 1986 is incomplete, with some imprecise species information. In updating this checklist, we examined and verified mosquito specimens collected from Singapore in various depositories, including a thorough review of past taxonomic literature. Here, we report a checklist of 182 mosquito species, 33 new distribution records, and a consolidated status list of vectors for Singapore. As Singapore is a travel hub and hosts one of the busiest container ports in the world, there is a risk of introducing mosquito species and their associated pathogens of human disease to the country. Hence, the distribution records are important to increase our knowledge on mosquito ecology as well as to understand the risk of newly introduced vectors and their associated pathogens.
  11. Life cycle assessment: Sustainability of biodiesel production from black soldier fly larvae feeding on thermally pre-treated sewage sludge under a tropical country setting
    Seng Liew C, Ren Mong G, Wei Lim J, Raksasat R, Rawindran H, Hong Leong W, et al.
    Waste Manag, 2023 Apr 20;164:238-249.
    PMID: 37086606 DOI: 10.1016/j.wasman.2023.04.013
    More energy is needed nowadays due to global population growth. Concurrently, sewage sludge generation has also increased steadily stemming from the inevitable urbanization. As such, black soldier fly larvae (BSFL) can be potentially deployed to solve both issues. This paper investigates the environmental sustainability of biodiesel production derived from sludge-fed BSFL feedstock. A cradle-to-gate life cycle assessment (LCA) was performed through SimaPro software utilizing the ReCiPe 2016 Midpoint (H) and Endpoint (H) methods. The entire LCA covered 3 main stages, including the thermal pre-treatment of sludge, BSFL rearing and processing, and lastly lipid extraction and biodiesel production. LCA showed that the sludge pre-treatment stage had the highest environmental impact, while BSFL rearing and processing had the least due to the suitable geographical climate. Electricity usage during the pre-treatment stage was the main contributing component, followed by chemical usage during biodiesel production. After normalizing, it was observed that land occupation, marine ecotoxicity, freshwater ecotoxicity and freshwater eutrophication were more impactful than the commonly studied global warming potential (GWP). Lipid content and biodiesel conversion efficiency were determined as the sensitive factors which could influence the LCA outcome. In comparison with other types of biodiesel, BSFL biodiesel had a milder impact in terms of climate change, land occupation, terrestrial acidification, marine and freshwater eutrophication. Furthermore, this biological reduction of sludge through BSFL valorization avoided sludge landfilling, which reduced up to 100 times GWP. Therefore, sludge-fed BSFL biodiesel production is an environmentally-sound and highly potential solution that should be investigated comprehensively.
  12. GENIPAC: A Genomic Information Portal for Head and Neck Cancer Cell Systems
    Lee BKB, Gan CP, Chang JK, Tan JL, Fadlullah MZ, Abdul Rahman ZA, et al.
    J Dent Res, 2018 07;97(8):909-916.
    PMID: 29512401 DOI: 10.1177/0022034518759038
    Head and neck cancer (HNC)-derived cell lines represent fundamental models for studying the biological mechanisms underlying cancer development and precision therapies. However, mining the genomic information of HNC cells from available databases requires knowledge on bioinformatics and computational skill sets. Here, we developed a user-friendly web resource for exploring, visualizing, and analyzing genomics information of commonly used HNC cell lines. We populated the current version of GENIPAC with 44 HNC cell lines from 3 studies: ORL Series, OPC-22, and H Series. Specifically, the mRNA expressions for all the 3 studies were derived with RNA-seq. The copy number alterations analysis of ORL Series was performed on the Genome Wide Human Cytoscan HD array, while copy number alterations for OPC-22 were derived from whole exome sequencing. Mutations from ORL Series and H Series were derived from RNA-seq information, while OPC-22 was based on whole exome sequencing. All genomic information was preprocessed with customized scripts and underwent data validation and correction through data set validator tools provided by cBioPortal. The clinical and genomic information of 44 HNC cell lines are easily assessable in GENIPAC. The functional utility of GENIPAC was demonstrated with some of the genomic alterations that are commonly reported in HNC, such as TP53, EGFR, CCND1, and PIK3CA. We showed that these genomic alterations as reported in The Cancer Genome Atlas database were recapitulated in the HNC cell lines in GENIPAC. Importantly, genomic alterations within pathways could be simultaneously visualized. We developed GENIPAC to create access to genomic information on HNC cell lines. This cancer omics initiative will help the research community to accelerate better understanding of HNC and the development of new precision therapeutic options for HNC treatment. GENIPAC is freely available at http://genipac.cancerresearch.my/ .
  13. Fulltext External quality assessment of dengue and chikungunya diagnostics in the Asia Pacific region, 2015
    Soh LT, Squires RC, Tan LK, Pok KY, Yang H, Liew C, et al.
    Western Pac Surveill Response J, 2016 04 22;7(2):26-34.
    PMID: 27508088 DOI: 10.5365/WPSAR.2016.7.1.002
    OBJECTIVE: To conduct an external quality assessment (EQA) of dengue and chikungunya diagnostics among national-level public health laboratories in the Asia Pacific region following the first round of EQA for dengue diagnostics in 2013.

    METHODS: Twenty-four national-level public health laboratories performed routine diagnostic assays on a proficiency testing panel consisting of two modules. Module A contained serum samples spiked with cultured dengue virus (DENV) or chikungunya virus (CHIKV) for the detection of nucleic acid and DENV non-structural protein 1 (NS1) antigen. Module B contained human serum samples for the detection of anti-DENV antibodies.

    RESULTS: Among 20 laboratories testing Module A, 17 (85%) correctly detected DENV RNA by reverse transcription polymerase chain reaction (RT-PCR), 18 (90%) correctly determined serotype and 19 (95%) correctly identified CHIKV by RT-PCR. Ten of 15 (66.7%) laboratories performing NS1 antigen assays obtained the correct results. In Module B, 18/23 (78.3%) and 20/20 (100%) of laboratories correctly detected anti-DENV IgM and IgG, respectively. Detection of acute/recent DENV infection by both molecular (RT-PCR) and serological methods (IgM) was available in 19/24 (79.2%) participating laboratories.

    DISCUSSION: Accurate laboratory testing is a critical component of dengue and chikungunya surveillance and control. This second round of EQA reveals good proficiency in molecular and serological diagnostics of these diseases in the Asia Pacific region. Further comprehensive diagnostic testing, including testing for Zika virus, should comprise future iterations of the EQA.

  14. Antibiotic use in a co-infection of respiratory syncytial virus and pathogenic bacteria in children in a resource-limited setting in northeast Peninsular Malaysia
    Liew CSL, Guad RM, Taylor-Robinson AW, Teck KS, Mandrinos S, Duin EV, et al.
    Trop Biomed, 2024 Sep 01;41(3):310-315.
    PMID: 39548785 DOI: 10.47665/tb.41.3.011
    To investigate co-infection of bacterial isolates associated with respiratory syncytial virus (RSV) in children aged less than two years who were admitted to hospital with confirmed lower respiratory tract infection (LRTI) in Kelantan, Malaysia. The demographic data, clinical history, case management, haematological as well as infectious parameters (white blood cell differential and count, plus C-reactive protein, CRP) of the patients were systematically recorded. Less than one-third of cases were RSV-positive (21.03% and 26.23% were diagnosed as acute bronchiolitis or pneumonia, respectively). Blood cultures from approximately 10% of patients demonstrated growth of Haemophilus influenzae, Staphylococcus aureus, coagulase-negative Staphylococcus, Pseudomonas stutzeri, haemolytic Streptococcus group A, and Bacillus subtilis. Further analysis indicated that children with positive bacterial growth had an insignificant predictive value of CRP (2.32-7.16 mg/dl). The total white cell counts were 2.97-7.33 x 109sup>/L despite increased lymphocyte values in the bacteria-positive blood culture. Platelet counts were also within normal limits except for a single case of H. influenzae infection (685.50 x 109sup>/L). Interestingly, 95.01% of patients were treated with antibiotics; 66.23% of RSV infection cases were administered with a combination of antibiotics and 33.77% with only a single antibiotic. The data indicate that the use of antibiotics, either singly or in combination, is not always effective in treating LRTI in infants. Alternative therapeutic regimens should be considered, especially in Asian countries that may have limited resources.
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