Displaying publications 61 - 73 of 73 in total

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  1. Lee KW, Tan WS
    J Virol Methods, 2008 Aug;151(2):172-180.
    PMID: 18584885 DOI: 10.1016/j.jviromet.2008.05.025
    The recombinant hepatitis B virus (HBV) core antigen (HBcAg) expressed in Escherichia coli self-assembles into icosahedral capsids of about 35 nm which can be exploited as gene or drug delivery vehicles. The association and dissociation properties of the C-terminally truncated HBcAg with urea and guanidine hydrochloride (GdnHCl) were studied. Transmission electron microscopy (TEM) revealed that the dissociated HBcAg was able to re-associate into particles when the applied denaturing agents were physically removed. In order to evaluate the potential of the particles in capturing molecules, purified green fluorescent protein (GFP) was applied to the dissociated HBcAg for encapsidation. The HBcAg particles harbouring the GFP molecules were purified using sucrose density gradient ultracentrifugation and analysed using native agarose gel electrophoresis and TEM. A method for the encapsidation of GFP in HBcAg particles which has the potential to capture drugs or nucleic acids was established.
  2. Tan FH, Kong JC, Ng JF, Alitheen NB, Wong CL, Yong CY, et al.
    J Appl Microbiol, 2021 Oct;131(4):2072-2080.
    PMID: 33629458 DOI: 10.1111/jam.15048
    AIMS: To display a short peptide (GSRSHHHHHH) at the C-terminal end of turnip yellow mosaic virus coat protein (TYMVc) and to study its assembly into virus-like particles (TYMVcHis6 VLPs).

    METHODS AND RESULTS: In this study, recombinant TYMVcHis6 expressed in Escherichia coli self-assembled into VLPs of approximately 30-32 nm. SDS-PAGE and Western blot analysis of protein fractions from the immobilized metal affinity chromatography (IMAC) showed that TYMVcHis6 VLPs interacted strongly with nickel ligands in IMAC column, suggesting that the fusion peptide is protruding out from the surface of VLPs. These VLPs are highly stable over a wide pH range from 3·0 to 11·0 at different temperatures. At pH 11·0, specifically, the VLPs remained intact up to 75°C. Additionally, the disassembly and reassembly of TYMVcHis6 VLPs were studied in vitro. Dynamic light scattering and transmission electron microscopy analysis revealed that TYMVcHis6 VLPs were dissociated by 7 mol l-1 urea and 2 mol l-1 guanidine hydrochloride (GdnHCl) without impairing their reassembly property.

    CONCLUSIONS: A 10-residue peptide was successfully displayed on the surface of TYMVcHis6 VLPs. This chimera demonstrated high stability under extreme thermal conditions with varying pH and was able to dissociate and reassociate into VLPs by chemical denaturants.

    SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first C-terminally modified TYMVc produced in E.  coli. The C-terminal tail which is exposed on the surface can be exploited as a useful site to display multiple copies of functional ligands. The ability of the chimeric VLPs to self-assemble after undergo chemical denaturation indicates its potential role to serve as a nanocarrier for use in targeted drug delivery.

  3. Chopra A, Lin HY, Navarra SV, Saeed MA, Sockalingam S, Thongpooswan S, et al.
    Int J Rheum Dis, 2021 Sep;24(9):1106-1111.
    PMID: 34375036 DOI: 10.1111/1756-185X.14185
    Rheumatoid arthritis (RA) is a major health burden in Asia Pacific affecting the quality of life of patients and consuming healthcare resources. According to recent estimates from the World Health Organization-International League Against Rheumatism-Community Oriented Program for Control of Rheumatic Diseases, prevalence is around 0.3%-0.5%. Management guidelines have helped to improve treatment across this diverse region. To gain better insight into current real-world management applications in view of these guidelines, virtual meetings were conducted in mid-2020 to explore perspectives of rheumatologists and patients, as well as discuss the impact of coronavirus disease 2019 on RA management. Patients and rheumatologists from Hong Kong, Malaysia, Singapore, the Philippines, Thailand, India, Pakistan, and Taiwan were included, representing a diverse mix of healthcare systems, wealth, ethnicity and culture. Despite many countries having prospered in recent years, similar challenges in RA diagnosis and treatment were identified. The daily impact and patient experience of RA were also similar across countries, marked by "silent" pain and disability, and universal misunderstanding of the disease. Late diagnosis and treatment, and barriers to access to appropriate treatment, remain problematic. The experience shared by Taiwan offers a glimmer of hope, however, wherein patient advocacy groups have succeeded in being included in policy-making decisions and securing access to advanced treatment. Real-world solutions that pay heed to the unique local needs and diversity of Asia Pacific are required to improve RA management, which will take time. In the interim, help can be sought from the trained, non-rheumatologist community to reduce some of the disease burden.
  4. Ng KP, Yew SM, Chan CL, Soo-Hoo TS, Na SL, Hassan H, et al.
    Eukaryotic Cell, 2012 May;11(5):705-6.
    PMID: 22544899 DOI: 10.1128/EC.00081-12
    Cladosporium sphaerospermum is one of the most widely distributed allergens causing serious problems in patients with respiratory tract disease. We report the 26,644,473-bp draft genome sequence and gene annotation of C. sphaerospermum UM843. Analysis of the genome sequence led to the finding of genes associated with C. sphaerospermum's melanin biosynthesis, allergens, and antifungal drug resistance.
  5. Lee KW, Yusof Khan AHK, Ching SM, Chia PK, Loh WC, Abdul Rashid AM, et al.
    Front Neurol, 2020;11:579070.
    PMID: 33123082 DOI: 10.3389/fneur.2020.579070
    Background: As the world witnessed the devastation caused by the coronavirus disease 2019 (COVID-19) outbreak, a growing body of literature on COVID-19 is also becoming increasingly available. Stroke has increasingly been reported as a complication of COVID-19 infection. However, a systematic synthesis of the available data has not been conducted. Therefore, we performed a systematic review and meta-analysis of currently available epidemiological, clinical, and laboratory data related to both stroke and COVID-19 infection. Methods: We systematically searched Medline, Cinahl, and PubMed for studies related to stroke and COVID-19 from inception up to June 4, 2020. We selected cohort studies, case series, and case reports that reported the occurrence of stroke in COVID-19 patients. A fixed-effects model was used to estimate the pooled frequency of stroke in COVID-19 patients with a 95% confidence interval (CI). Results: Twenty-eight studies were included in the systematic review and seven studies for the meta-analysis. The pooled frequency of stroke in COVID-19 patients was 1.1% (95% CI: 0.8, 1.3). The heterogeneity was low (I2 = 0.0%). Even though the frequency of stroke among patients having COVID-19 infection was low, those with concomitant COVID-19 infection and stroke suffered from a more severe infection and eventually had a poorer prognosis with a higher mortality rate (46.7%) than COVID-19 alone. Many COVID-19 patients shared the common traditional risk factors for stroke. We noted that ischemic stroke involving the anterior circulation with large vessels occlusion is the most common type of stroke with more strokes seen in multi-territorial regions, suggesting systemic thromboembolism. An elevated level of D-dimers, C-reactive protein, ferritin, lactic acid dehydrogenase, troponin, ESR, fibrinogen, and a positive antiphospholipid antibody were also noted in this review. Conclusions: The occurrence of stroke in patients with COVID-19 infection is uncommon, but it may pose as an important prognostic marker and indicator of severity of infection, by causing large vessels occlusion and exhibiting a thrombo-inflammatory vascular picture. Physicians should be made aware and remain vigilant on the possible two-way relationship between stroke and COVID-19 infection. The rate of stroke among patients with COVID-19 infection may increase in the future as they share the common risk factors.
  6. Devaraj NK, Suppiah S, Veettil SK, Ching SM, Lee KW, Menon RK, et al.
    Nutrients, 2019 Nov 27;11(12).
    PMID: 31783578 DOI: 10.3390/nu11122886
    The protective effects of probiotic supplementation against radiation-induced diarrhea (RID) have been reported in previous systematic reviews; however so far, only non-conclusive results have been obtained. The objective of this study was to systematically update and evaluate the available evidence for probiotic supplementation. The protocol of this systematic review has been registered (CRD42018106059) with the International Prospective Register of Systematic Reviews (PROSPERO). The primary efficacy outcome was the incidence of RID. Secondary outcomes were the incidence of watery stool, soft stool, and antidiarrheal medication use. There were eight trials, and a total of 1116 participants were included in the primary analysis. Compared with placebo, probiotics were associated with a lower risk of RID [risk ratio (RR) = 0.62, 95% CI = 0.46, 0.83]. A requisite heterogeneity-adjusted trial sequential analysis indicated conclusive evidence for this beneficial effect. No statistically significant reduction in RID (RR = 0.52, 95% CI = 0.14, 1.91) was observed on subgroup analysis in patients receiving both radiation therapy and chemotherapy. However, those patients receiving only radiation therapy (RT) demonstrated significant benefit (RR = 0.61, 95% CI = 0.48, 0.78). There was a significant difference in the antidiarrheal medication use (RR = 0.54, 95% CI = 0.35, 0.84) observed with the use of probiotics. However, no significant difference was observed for the incidence of soft and watery stool. The use of probiotics is beneficial in preventing RID in patients receiving RT.
  7. Ching SM, Lee KW, Yee A, Sivaratnam D, Hoo FK, Wan Sulaiman WA, et al.
    Med J Malaysia, 2020 09;75(5):561-567.
    PMID: 32918427
    INTRODUCTION: This study aimed to validate the Malay version of the short form Smartphone Addiction Scale (SAS-M-SF) and to examine its psychometric properties in a cohort of pre-university adolescents.

    METHODS: We obtained the validity and reliability evidence for the SAS-M-SF using a group of 307 pre-university students in Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia with a mean age of 18.4±0.2 years (70.4% female and 29.6% male). A questionnaire containing the Malay version of Smartphone Addiction Scale (SAS-M), the Malay version of the short form Smartphone Addiction Scale (SAS-M-SF), and the Malay version of the Internet Addiction Test (IAT-M) was administered on the adolescents.

    RESULTS: The SAS-M-SF displayed good internal consistency (Cronbach's α=0.80). Using principle component analysis, we identified a 4-factor SAS-M-SF model. A significant correlation between the SAS-M-SF and the IAT-M was found, lending support for concurrent validity. The prevalence of smartphone addiction was 54.5% based on cut-off score of ≥36 with a sensitivity of 70.2% and a specificity of 72.5%.

    CONCLUSIONS: The 10-item SAS-M-SF is a valid and reliable screening tool for smartphone addiction among adolescents. The scale can help clinicians or educators design appropriate intervention and prevention programs targeting smartphone addiction in adolescents at clinical or school settings.

  8. Chin CT, Lee KW
    Br. J. Cancer, 1970 Sep;24(3):427-32.
    PMID: 5475750
    Changes in the buccal mucosa of 296 Indian and Malay betel-nut chewers in Perak, West Malaysia, were studied clinically. 167 out of 212 Indian subjects incorporated tobacco in their quids, while 45 out of 84 Malay subjects incorporated. "Gambir". The Indians appeared to show a higher proportion of mucosal changes, particularly when tobacco was used. "Gambir" did not appear to be potent in the production of mucosal changes. Comparison with studies in other parts of the world suggested comparable findings with respect to both tobacco and non-tobacco chewing samples, and there would appear to be some evidence that tobacco-containing quids are likely to produce a higher proportion of mucosal changes as compared to non-tobacco-containing quids. An attempt to demonstrate a dose-effect relationship by dividing the subjects into "slight" and "heavy" chewers did not yield significant differences between these two categories in each of the groups.
  9. Lee KW, Chin CT
    Br. J. Cancer, 1970 Sep;24(3):433-41.
    PMID: 5475751
    Sixty-two "leukoplakias" from the cheeks of betel-nut chewers in West Malaysia were studied histologically. Ten biopsies were from non-tobacco betel-nut chewers. An amorphous von Kossa positive layer was seen on the keratin surface in 42 specimens. Tobacco did not appear essential for its formation, and it appeared to be significantly associated with parakeratosis. Its possible significance as a cuticle-like layer prolonging contact between carcinogens and the mucosa is discussed.Parakeratosis appeared to be the most common form of cornification seen, and the mitotic activity in parakeratinized leukoplakias appeared to be significantly greater than orthokeratinized leukoplakias.Comparison with studies on other population samples using different quids suggested that severe histological changes were more likely to be seen when tobacoo-containing quids were chewed as compared to non-tobacco-containing quids.An attempt to correlate the histological changes seen with the clinical habit in leukoplakias from chewers using tobacco-containing quids suggested that epithelial atrophy appeared to be significantly related to the duration of the habit but not to the "intensity" of the habit.
  10. Ooi EH, Lee KW, Yap S, Khattab MA, Liao IY, Ooi ET, et al.
    Comput Biol Med, 2019 03;106:12-23.
    PMID: 30665137 DOI: 10.1016/j.compbiomed.2019.01.003
    Effects of different boundary conditions prescribed across the boundaries of radiofrequency ablation (RFA) models of liver cancer are investigated for the case where the tumour is at the liver boundary. Ground and Robin-type conditions (electrical field) and body temperature and thermal insulation (thermal field) conditions are examined. 3D models of the human liver based on publicly-available CT images of the liver are developed. An artificial tumour is placed inside the liver at the boundary. Simulations are carried out using the finite element method. The numerical results indicated that different electrical and thermal boundary conditions led to different predictions of the electrical potential, temperature and thermal coagulation distributions. Ground and body temperature conditions presented an unnatural physical conditions around the ablation site, which results in more intense Joule heating and excessive heat loss from the tissue. This led to thermal damage volumes that are smaller than the cases when the Robin type or the thermal insulation conditions are prescribed. The present study suggests that RFA simulations in the future must take into consideration the choice of the type of electrical and thermal boundary conditions to be prescribed in the case where the tumour is located near to the liver boundary.
  11. Yew SM, Chan CL, Kuan CS, Toh YF, Ngeow YF, Na SL, et al.
    BMC Genomics, 2016 Feb 03;17:91.
    PMID: 26842951 DOI: 10.1186/s12864-016-2409-8
    Ochroconis mirabilis, a recently introduced water-borne dematiaceous fungus, is occasionally isolated from human skin lesions and nails. We identified an isolate of O. mirabilis from a skin scraping with morphological and molecular studies. Its genome was then sequenced and analysed for genetic features related to classification and biological characteristics.
  12. Chan NN, Ong KW, Siau CS, Lee KW, Peh SC, Yacob S, et al.
    BMC Public Health, 2022 02 14;22(1):296.
    PMID: 35164734 DOI: 10.1186/s12889-022-12632-z
    BACKGROUND: The COVID-19 pandemic has resulted in a global health emergency and lock-down measures to curb the uncontrolled transmission chain. Vaccination is an effective measure against COVID-19 infections. In Malaysia amidst the national immunisation programme (NIP) which started in February 2021, there were rising concerns regarding the prevalence of vaccine hesitancy and refusal, and therefore, vaccine uptake among Malaysians. Although there are many quantitative studies on COVID-19 vaccination, the subjective experience of individuals was understudied. This study aims to explore the lived experiences of Malaysians regarding vaccine hesitancy and refusal, and facilitating factors that could enhance vaccine acceptance and uptake.

    METHODS: This qualitative study employed the hermeneutic phenomenological study design. Purposive sampling strategies were used to recruit Malaysians that had direct experiences with friends, family members and their community who were hesitating or refusing to accept the COVID-19 vaccines. A semi-structured interview guide was developed based on the expert knowledge of the investigators and existing literature on the topic. A series of focus group interviews (FGIs) was conducted online facilitated by a multidisciplinary team of experts. The group interviews were transcribed verbatim and analysed.

    RESULTS: Fifty-nine participants took part in seven FGIs. We found that "incongruence" was the overall thematic meaning that connected all the 3 main themes. These themes comprise firstly, the incongruence between the aims and implementation of the National Immunization Program which highlighted the gap between realities and needs on the ground. Secondly, the incongruence between Trust and Mistrust revealed a trust deficit in the government, COVID-19 news, and younger people's preference to follow the examples of local vaccination "heroes". Thirdly, the incongruence in communication showed the populace's mixed views regarding official media and local social media.

    CONCLUSIONS: This study provided rich details on the complex picture of the COVID-19 immunization program in Malaysia and its impact on vaccine hesitancy and refusal. The inter-related and incongruent factors explained the operational difficulty and complexity of the NIP and the design of an effective health communication campaign. Identified gaps such as logistical implementation and communication strategies should be noted by policymakers in implementing mitigation plans.

  13. Ang CS, Lee KW, Voon SP, Ho MC, Tan CE, Ching SM, et al.
    Oman Med J, 2023 Jan;38(1):e456.
    PMID: 36937773 DOI: 10.5001/omj.2023.20
    OBJECTIVES: From early 2020, Malaysia had to implement nationwide lockdowns, quarantines, and other social distancing practices to contain the spread of COVID-19 virus, leading to symptoms of psychosocial burnout among the people. The aim of the present research is to develop and validate a Malay language version of the COVID-19 Burnout Scale (M-COVID-19-BS).

    METHODS: This three-phase study was conducted among Malaysian population. Phase 1 involved forward and backward translations of the Scale to Malay language by four professional bilingual translators. In Phase 2, the new M-COVID-19-BS instrument was piloted on 30 participants who suggested minor lexical modifications. Phase 3 consisted of online recruiting of Malaysian citizens to answer a composite questionnaire comprising the M-COVID-19-BS, Copenhagen Burnout Inventory (CBI), World Health Organization Quality of Life Scale Abbreviated Version (WHOQOL-BREF), and Fear of COVID-19 Scale (FCV-19S). Data were statistically analyzed.

    RESULTS: The composite four-part questionnaire in Malay was answered by N = 225 Malaysian citizens. The M-COVID-19-BS instrument demonstrated a good internal consistency (Cronbach's alpha = 0.926) and had a unidimensional factor structure. M-COVID-19-BS scores positively correlated with the three CBI subscales, showing evidence of convergent validity. Negative correlation was reported between M-COVID-19-BS and WHOQOL-BREF, achieving discriminant validity. M-COVID-19-BS also exhibited moderate positive correlations with the FCV-19S, thus supporting its concurrent validity.

    CONCLUSIONS: Results demonstrate that M-COVID-19-BS is a valid and reliable instrument to assess burnout symptoms related to COVID-19 among Malay-speaking populations either collectively or as a self-care tool to detect burnout symptoms without needing to further burden the already overwhelmed Malaysian healthcare system.

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