Displaying publications 1 - 20 of 54 in total

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  1. Mohidin TB, Ng CC
    J Biosci, 2015 Mar;40(1):41-51.
    PMID: 25740140
    Epstein-Barr virus (EBV)-encoded BARF1 (BamH1-A Rightward Frame-1) is expressed in EBV-positive malignancies such as nasopharyngeal carcinoma, EBV-associated gastric cancer, B-cell lymphoma and nasal NK/T-cell lymphoma, and has been shown to have an important role in oncogenesis. However, the mechanism by which BARF1 elicits its biological effects is unclear. We investigated the effects of BARF1 silencing on cell proliferation and apoptosis in EBV-positive malignant cells. We observed that BARF1 silencing significantly inhibits cell proliferation and induces apoptosis-mediated cell death by collapsing the mitochondrial membrane potential in AG876 and Hone-Akata cells. BARF1 knockdown up-regulates the expression of pro-apoptotic proteins and downregulates the expression of anti-apoptotic proteins. In BARF1-down-regulated cells, the Bcl-2/BAX ratio is decreased. The caspase inhibitor z-VAD-fmk was found to rescue siBARF1-induced apoptosis in these cells. Immunoblot analysis showed significant increased levels of cleaved caspase 3 and caspase 9. We observed a significant increase in cytochrome c level as well as the formation of apoptosome complex in BARF1-silenced cells. In conclusion, siRNA-mediated BARF1 down-regulation induces caspase-dependent apoptosis via the mitochondrial pathway through modulation of Bcl-2/BAX ratio in AG876 and Hone-Akata cells. Targeting BARF1 using siRNA has the potential to be developed as a novel therapeutic strategy in the treatment of EBV-associated malignancies.
  2. Amy Hui-Ping Khor, Lim, Kheng-Seang, Tan, Chong-Tin, Seinn Mya Mya Aye, Yan Lynn Aung, Yin Minn Aye, et al.
    Neurology Asia, 2017;22(3):283-285.
    MyJurnal
    Genetic predisposition to carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS) and toxic
    epidermal necrolysis (TEN) had been reported in several Southeast Asian populations, but not in
    Myanmar. Previous studies had so far reported more than 70% of CBZ-induced SJS/TEN cases
    positive for HLA-B*15:02 allele.1-4 Myanmar, as the second largest country in Southeast Asia with a
    population of 54.5 million, has high HLA-B*15:02 carrier frequency in its general population (27.3-
    49.1%).5,6 We investigated the association of HLA-B alleles and CBZ-induced SJS/TEN in Myanmar
    population. HLA-B*15:02 was detected in 3/3 (100%) of cases and 6/53 (11.3%) of tolerant controls,
    and HLA-B*15:02 is significantly associated with CBZ-SJS/TEN in Myanmar population (OR 51.2,
    95% CI 2.36-1106.95, p=0.003). (Copied from article)
  3. Herlyani Khosama, Astri Budikayanti, Amy Hui Ping Khor, Lim, Kheng Seang, Ng, Ching-Ching, Indra G. Mansyur, et al.
    Neurology Asia, 2017;22(2):113-116.
    MyJurnal
    Background & Objective: Association between HLA-B*1502 and carbamazepine-induced StevenJohnson
    syndrome/toxic epidermal necrolysis (CBZ-SJS/TEN) was reported in many Southeast Asian
    populations but not in Indonesian. The purpose of this study was to evaluate the association between
    HLA-B*1502 andCBZ-SJS/TEN in an Indonesian population.

    Methods: Patients with history of
    CBZ-SJS/TEN are recruited as cases and those who tolerated CBZ as controls. HLA-B typing was
    performed.

    Results: We recruited 14 cases with CBZ-SJS/TEN and 53 controls. Positive HLA-B*1502
    was found in 8 (57.1%) cases and 14 (26.4%) controls (OR 3.7, 95% CI 1.09-12.61, p=0.035).

    Conclusion: HLA-B*1502 is associated with CBZ-SJS/TEN patients in Indonesian.
  4. Toh, Tsun-Haw, Lim, Kheng-Seang, Ng, Ching-Ching, Imran Idris, Sherrini Bazir Ahmad, Lim, Thien-Thien, et al.
    MyJurnal
    Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease of small cerebral arteries. This case series aims to describe the mutations in NOTCH3and their phenotypes in Malaysia. We includedpatients who were genetically confirmed to have CADASIL, diagnosed at the University of Malaya Medical Centre, Malaysia. Family members who fulfilled clinical or imaging criteria, and patients from two previous published Malaysian families were also included. Six families (eleven cases) were included in this series. Genetic testing revealed NOTCH3 mutations in c.328C>T (p.Arg110Cys, R110C), c.553T>G (p.Cys185Gly, C185G), c.1630C>T (p.Arg544Cys, R544C) and c.160C>T (p.Arg54Cys, R54C). Two out of four Chinese families had R544C mutation in exon 11, with a later age of onset, absence of migraine and lack of anterior temporal pole involvement on MRI. One family with mixed Indian and Chinese ancestry had a mutation in exon 3 with R110C and another Indian family exon 4 with C185G mutation. This case series highlights the genotypic and phenotypic variability of CADASIL in a multi-ethniccountry. The finding of p.Arg544Cys mutation among the older Chinese families, similar to those reported in Jeju Island and Taiwan, suggest the need to screen the older Chinese stroke patients with typical MRI changes.
  5. Bong IPN, Ng CC, Baharuddin P, Zakaria Z
    Genes Genomics, 2017;39(5):533-540.
    PMID: 28458781 DOI: 10.1007/s13258-017-0518-7
    Epigenetic changes have emerged as key causes in the development and progression of multiple myeloma (MM). In this study, global microRNA (miRNA) expression profiling were performed for 27 MM (19 specimens and 8 cell lines) and 3 normal controls by microarray. miRNA-targets were identified by integrating the miRNA expression profiles with mRNA expression profiles of the matched samples (unpublished data). Two miRNAs were selected for verification by RT-qPCR (miR-150-5p and miR-4430). A total of 1791 and 8 miRNAs were over-expressed and under-expressed, respectively in MM compared to the controls (fold change ≥2.0; p 
  6. Yeo KS, Mohidin TB, Ng CC
    C. R. Biol., 2012 Dec;335(12):713-21.
    PMID: 23312294 DOI: 10.1016/j.crvi.2012.11.002
    Epstein-Barr virus (EBV) is a ubiquitous tumor-causing virus which infects more than 90% of the world population asymptomatically. Recent studies suggest that LMP-1, -2A and -2B cooperate in the tumorigenesis of EBV-associated epithelial cancers such as nasopharygeal carcinoma, oral and gastric cancer. In this study, LMPs were expressed in the HEK293T cell line to reveal their oncogenic mechanism via investigation on their involvement in the regulation of the cell cycle and genes that are involved. LMPs were expressed in HEK293T in single and co-expression manner. The transcription of cell cycle arrest genes were examined via real-time PCR. Cell cycle progression was examined via flow cytometry. 14-3-3σ and Reprimo were upregulated in all LMP-1 expressing cells. Moreover, cell cycle arrest at G(2)/M progression was detected in all LMP-1 expressing cells. Therefore, we conclude that LMP-1 may induce cell cycle arrest at G(2)/M progression via upregulation of 14-3-3σ and Reprimo.
  7. Lim CS, Krishnan G, Sam CK, Ng CC
    Clin Chim Acta, 2013 Jan 16;415:158-61.
    PMID: 23043757 DOI: 10.1016/j.cca.2012.08.031
    Because blocking agent occupies most binding surface of a solid phase, its ability to prevent nonspecific binding determines the signal-to-noise ratio (SNR) and reliability of an enzyme-linked immunosorbent assay (ELISA).
  8. Lim CS, Goh SL, Krishnan G, Ng CC
    Protein Expr Purif, 2014 Mar;95:8-12.
    PMID: 24291446 DOI: 10.1016/j.pep.2013.11.007
    This paper describes the recombinant production of a biologically active Epstein-Barr virus BZLF1 trans-activator, i.e., Z-encoded broadly reactive activator (ZEBRA), that recognized specific DNA motifs. We used auto-induction for histidine-tagged BZLF1 expression in Escherichia coli and immobilized cobalt affinity membrane chromatography for protein purification under native conditions. We obtained the purified BZLF1 at a yield of 5.4mg per gram of wet weight cells at 75% purity, in which 27% of the recombinant BZLF1 remained biologically active. The recombinant BZLF1 bound to oligonucleotides containing ZEBRA response elements, either AP-1 or ZIIIB, but not a ZIIIB mutant. The recombinant BZLF1 showed a specific DNA-binding activity which could be useful for functional studies.
  9. Fong CY, Kong AN, Noordin M, Poh BK, Ong LC, Ng CC
    Eur. J. Paediatr. Neurol., 2018 Jan;22(1):155-163.
    PMID: 29122496 DOI: 10.1016/j.ejpn.2017.10.007
    INTRODUCTION: Children with epilepsy on long-term antiepileptic drugs (AEDs) are at risk of low bone mineral density (BMD). The aims of our study were to evaluate the prevalence and determinants of low BMD among Malaysian children with epilepsy.

    METHOD: Cross-sectional study of ambulant children with epilepsy on long-term AEDs for >1 year seen in a tertiary hospital in Malaysia from 2014 to 2015. Detailed assessment of anthropometric measurements; environmental lifestyle risk factors; serum vitamin D, calcium and parathyroid hormone levels; genotyping of single nucleotide polymorphisms of genes in vitamin D and calcium metabolism; and lumbar spine BMD were obtained. Low BMD was defined as BMD Z-score ≤ -2.0 SD.

    RESULTS: Eighty-seven children with mean age of 11.9 years (56 males) participated in the study. The prevalence of low lumbar BMD was 21.8% (19 patients). Multivariate logistic regression analysis identified polytherapy >2 AEDs (OR: 7.86; 95% CI 1.03-59.96), small frame size with wrist breadth of <15th centile (OR 14.73; 95% CI 2.21-98.40), and body mass index Z-score 2 AEDs, underweight or with small frame size as they are at higher risk of having low BMD.

  10. Low JSY, Chew LL, Ng CC, Goh HC, Lehette P, Chong VC
    J Therm Biol, 2018 May;74:14-22.
    PMID: 29801619 DOI: 10.1016/j.jtherbio.2018.02.012
    Heat shock response (HSR), in terms of transcription regulation of two heat shock proteins genes hsp70 and hsp90), was analysed in a widespread tropical copepod Pseudodiaptomus annandalei. The mRNA transcripts of both genes were quantified after copepods at a salinity of 20 underwent an acclimation process involving an initial acclimation temperature of 29 °C, followed by gradual thermal ramping to the target exposure temperature range of 24-36 °C. The respective cellular HSR and organismal metabolism, measured by respiratory activity at exposure temperatures, were compared. The fold change in mRNA expression for both hsp70 and hsp90 (8-9 fold) peaks at 32 °C, which is very close to 32.4 °C, the upper thermal optimum for respiration in the species. Unexpectedly, the modelled HSR curves peak at only 3 °C (hsp90) and 3.5 °C (hsp70) above the mean water temperature (29.32 °C) of the copepod in the field. We propose that copepods in tropical waters adopt a preparative HSR strategy, early at the upper limit of its thermal optimum, due to the narrow thermal range of its habitat thus precluding substantial energy demand at higher temperatures. However, the model suggests that the species could survive to at least 36 °C with short acclimation time. Nevertheless, the significant overlap between its thermal range of hsp synthesis and the narrow temperature range of its habitat also suggests that any unprecedented rise in sea temperature would have a detrimental effect on the species.
  11. Kee BP, Ng JG, Ng CC, Hilmi I, Goh KL, Chua KH
    J Dig Dis, 2020 Jan;21(1):29-37.
    PMID: 31654602 DOI: 10.1111/1751-2980.12829
    OBJECTIVE: To investigate the association between genetic polymorphisms in ATG16L1 and IRGM genes and the development of Crohn's disease (CD) in Malaysian patients.

    METHODS: Altogether 335 participants were recruited, including 85 patients with CD and 250 unrelated healthy controls, and their informed consent was obtained. Genomic DNA was extracted via a conventional phenol-chloroform extraction method. Six single nucleotide polymorphisms (SNPs) in ATG16L1 and IRGM genes were genotyped using TaqMan SNP genotyping assays. Associations between SNP and CD were determined using Fisher's exact test, odds ratio, and 95% confidence interval. Statistical power and the Hardy-Weinberg equilibrium were also calculated.

    RESULTS: Two SNPs (rs2241880 and rs6754677) in the ATG16L1 gene were significantly associated with the onset of CD in the Malaysian population. The A allele and homozygous A/A genotype of the rs2241880 A/G polymorphism were protective against CD in the overall Malaysian and Malay population. The G allele and homozygous G/G genotype of the rs6754677 G/A polymorphism were protective in the Indian population, whereas the homozygous A/A genotype showed a risk of developing CD. The homozygous G/G genotype of IRGM rs11747270 was significantly present in the controls. However, this significance was not observed in a race-stratified analysis. All three ATG16L1 SNPs were associated with inflamed terminal ileum. IRGM rs4958847 and rs11747270 increased the risk of developing arthritis in patients with CD.

    CONCLUSION: We found a significant association between SNP, which are located in autophagy-related genes, and CD in a Malaysian population.

  12. Chan CK, Low JS, Lim KS, Low SK, Tan CT, Ng CC
    Neurol Sci, 2020 Mar;41(3):591-598.
    PMID: 31720899 DOI: 10.1007/s10072-019-04122-9
    INTRODUCTION: Genetic (idiopathic) generalized epilepsy (GGE) is a common form of epilepsy characterized by unknown aetiology and a presence of genetic component in its predisposition.

    METHODS: To understand the genetic factor in a family with GGE, we performed whole exome sequencing (WES) on a trio of a juvenile myoclonic epilepsy/febrile seizure (JME/FS) proband with JME/FS mother and healthy father. Sanger sequencing was carried out for validation of WES results and variant detection in other family members.

    RESULTS: Predictably damaging variant found in affected proband and mother but absent in healthy father in SCN1A gene was found to be associated with generalized epilepsy and febrile seizure. The novel non-synonymous substitution (c.5753C>T, p.S1918F) in SCN1A was found in all family members with GGE, of which 4/8 were JME subtypes, and/or febrile seizure, while 3 healthy family member controls did not have the mutation. This mutation was also absent in 41 GGE patients and 414 healthy Malaysian Chinese controls.

    CONCLUSION: The mutation is likely to affect interaction between the sodium channel and calmodulin and subsequently interrupt calmodulin-dependent modulation of the channel.

  13. Chu C, Loh KH, Ng CC, Ooi AL, Konishi Y, Huang SP, et al.
    Zool Stud, 2019;58:e30.
    PMID: 31966331 DOI: 10.6620/ZS.2019.58-30
    Larval descriptions of tropical marine and coastal fishes are very few, and this taxonomic problem is further exacerbated by the high diversity of fish species in these waters. Nonetheless, accurate larval identification in ecological and early life history studies of larval fishes is crucial for fishery management and habitat protection. The present study aimed to evaluate the usefulness of DNA barcodes to support larval fish identification since conventional dichotomous keys based on morphological traits are not efficient due to the lack of larval traits and the rapid morphological changes during ontogeny. Our molecular analysis uncovered a total of 48 taxa (21 families) from the larval samples collected from the Klang Strait waters encompassing both spawning and nursery grounds of marine and estuarine fishes. Thirty-two (67%) of the larval taxa were identified at the species level, two taxa (4%) at the genus level, and 14 taxa (29%) at family level. The relatively low rate of species-level identification is not necessarily due to the DNA barcoding method per se, but a general lack of reference sequences for speciose and non- commercial fish families such as Gobiidae, Blenniidae, and Callionymidae. Larval morphology remains important in species diagnoses when molecular matches are ambiguous. A lower ethanol percentage (50%) for larva preservation is also useful to keep the body of larvae intact for morphological identification, and to preserve DNA for subsequent molecular analyses. The 10% Chelex resin used to extract DNA is also cost- effective for long term monitoring of larval fishes. Hence, the DNA barcoding method is an effective and easy way to aid the identification of estuarine larval fishes at the species level.
  14. Bong IP, Ng CC, Fakiruddin SK, Lim MN, Zakaria Z
    Bosn J Basic Med Sci, 2016 Nov 10;16(4):268-275.
    PMID: 27754828 DOI: 10.17305/bjbms.2016.1568
    Multiple myeloma (MM) is a malignancy of B lymphocytes or plasma cells. Our array-based comparative genomic hybridization findings revealed chromosomal gains at 7q22.3 and 1q42.3, where nicotinamide (NAM) phosphoribosyltransferase (NAMPT) and lysosomal trafficking regulator (LYST) genes are localized, respectively. This led us to further study the functions of these genes in myeloma cells. NAMPT is a key enzyme involved in nicotinamide adenine dinucleotide salvage pathway, and it is frequently overexpressed in human cancers. In contrast, little is known about the function of LYST in cancer. The expression of LYST is shown to affect lysosomal size, granule size, and autophagy in human cells. In this study, the effects of small interfering RNA (siRNA)-mediated silencing of NAMPT and LYST on cell proliferation and apoptosis were evaluated in RPMI 8226 myeloma cells. Transfection efficiencies were determined by quantitative real time reverse transcriptase PCR. Cell proliferation was determined using MTT assay, while apoptosis was analyzed with flow cytometry using Annexin V-fluorescein isothiocyanate/propidium iodide assay. The NAMPT protein expression in siRNA-treated cells was estimated by enzyme-linked immunosorbent assay. Our results showed that NAMPT and LYST were successfully knockdown by siRNA transfection (p < 0.05). NAMPT or LYST gene silencing significantly inhibited cell proliferation and induced apoptosis in RPMI 8226 cells (p < 0.05). Silencing of NAMPT gene also decreased NAMPT protein levels (p < 0.01). Our study demonstrated that NAMPT and LYST play pivotal roles in the molecular pathogenesis of MM. This is the first report describing the possible functions of LYST in myelomagenesis and its potential role as a therapeutic target in MM.
  15. Lim KS, Ng CC, Chan CK, Foo WS, Low JS, Tan CT
    Seizure, 2017 Feb;45:24-27.
    PMID: 27912112 DOI: 10.1016/j.seizure.2016.11.011
    PURPOSE: Ethnic variation in epilepsy classification was reported in the Epilepsy Phenome/Genome Project. This study aimed to determine the ethnic variation in the prevalence of genetic (idiopathic) generalized epilepsy (GGE) and GGE with family history in a multi-ethnic Asian population in Malaysia.

    METHOD: In this cross-sectional study, 392 patients with a clinical diagnosis of GGE were recruited in the neurology outpatient clinic, University of Malaya Medical Centre (UMMC), from January 2011 till April 2016.

    RESULTS: In our epilepsy cohort (n=2100), 18.7% were diagnosed to have GGE. Of those, 28.6% >(N=112) had family history of epilepsy with a mean age of seizure onset of 16.5 years old, and 42.0% had myoclonic seizures (N=47). The lifetime prevalence of epilepsy among first-degree relative of those with GGE and positive family history was 15.0%. Analysis according to ethnicity showed that Malaysian Chinese had the lowest percentage of GGE among those with epilepsy (12.3%), as compared with Indian and Malay (25.3% and 21.3%, p<0.001). In addition, 32.1% of these Indian patients with GGE had positive family history, which is more than the Malay (26.4%) and Chinese (27.5%) ethnic groups. Consanguineous marriage was noted in 5 Indian families with positive family history (9.6%).

    CONCLUSION: There was ethnic variation in the prevalence of GGE, whereby the Malaysian Chinese had the lowest percentage of GGE as compared with Indian and Malay. A substantial proportion of GGE had positive family history among the three ethnics groups.

    Study site: neurology outpatient clinic, University of Malaya Medical Centre (UMMC)
  16. Khor AH, Lim KS, Tan CT, Kwan Z, Tan WC, Wu DB, et al.
    Pharmacogenet Genomics, 2017 07;27(7):275-278.
    PMID: 28570299 DOI: 10.1097/FPC.0000000000000287
    The majority of the carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis CBZ-SJS/TEN are associated with HLA-B*15:02 in Asian populations where this allele is common. In contrast, the association with HLA-A*31:01 is only reported in Japanese and Europeans. This study aimed to further investigate the association with HLA-A*31:01 besides HLA-B*15:02 in a multiethnic Malaysian population. Twenty-eight CBZ-SJS/TEN cases and 227 CBZ-tolerant controls were recruited. Association was tested by comparing carrier frequencies of the alleles between cases and controls. Significant associations were detected between HLA-B*15:02 and CBZ-SJS/TEN in independent ethnic groups: Malays [P=2.00×10; odds ratio (OR): 49.0; 95% confidence interval (CI): 9.36-256.81], Chinese (P=0.0047; OR: 14.3; 95% CI: 2.38-86.03) and Indians (P=0.04; OR: 13.8; 95% CI: 1.51-124.99). Combined analysis of all ethnic groups showed a significant association with OR Cochran-Mantel-Haenszel (ORCMH) of 26.6 (95% CI: 12.80-55.25; PCMH=2.31×10). In Indians, HLA-A*31:01 was found to be associated significantly with CBZ-SJS/TEN (P=0.023; OR: 10.4; 95% CI: 1.64-65.79) and combined analyses of both variants, HLA-A*31:01 and HLA-B*15:02, increased the strength of the association (P=0.0068; OR: 14.3; 95% CI: 2.20-92.9). Besides HLA-B*15:02, our study found a new association between HLA-A*31:01 and CBZ-SJS/TEN in Indians.
  17. Ivyna Bong PN, Ng CC, Lam KY, Megat Baharuddin PJ, Chang KM, Zakaria Z
    Mol Cytogenet, 2014;7(1):24.
    PMID: 24690091 DOI: 10.1186/1755-8166-7-24
    Multiple myeloma is an incurable disease. Little is known about the genetic and molecular mechanisms governing the pathogenesis of multiple myeloma. The risk of multiple myeloma predispositions varies among different ethnicities. More than 50% of myeloma cases showed normal karyotypes with conventional cytogenetic analysis due to the low mitotic activity and content of plasma cells in the bone marrow. In the present study, high resolution array comparative genomic hybridization technique was used to identify copy number aberrations in 63 multiple myeloma patients of Malaysia.
  18. Chua KH, Hilmi I, Ng CC, Eng TL, Palaniappan S, Lee WS, et al.
    J Dig Dis, 2009 May;10(2):124-30.
    PMID: 19426395 DOI: 10.1111/j.1751-2980.2009.00374.x
    The NOD2/CARD15 gene has been identified as an important susceptibility gene for Crohn's disease (CD) but the three common disease predisposing mutations (DPM) found in developed countries have not been identified in Asian populations. The aim of our study was to look for the DPM in our multiracial population and to discover whether there were any differences in the three major ethnic groups; Malay, Chinese and Indian.
  19. Ang CC, Lee SL, Lee CT, Tnah LH, Zakaria RM, Ng CC
    Am J Bot, 2011 May;98(5):e117-9.
    PMID: 21613176 DOI: 10.3732/ajb.1000494
    Microsatellite markers were developed for Johannesteijsmannia lanceolata to assess the genetic diversity and mating system of this alarmingly endangered species.
  20. Sim EU, Ang CH, Ng CC, Lee CW, Narayanan K
    J Hum Genet, 2010 Feb;55(2):118-20.
    PMID: 19927161 DOI: 10.1038/jhg.2009.124
    Extraribosomal functions of human ribosomal proteins (RPs) include the regulation of cellular growth and differentiation, and are inferred from studies that linked congenital disorders and cancer to the deregulated expression of RP genes. We have previously shown the upregulation and downregulation of RP genes in tumors of colorectal and nasopharyngeal carcinomas (NPCs), respectively. Herein, we show that a subset of RP genes for the large ribosomal subunit is differentially expressed among cell lines derived from the human nasopharyngeal epithelium. Three such genes (RPL27, RPL37a and RPL41) were found to be significantly downregulated in all cell lines derived from NPC tissues compared with a nonmalignant nasopharyngeal epithelial cell line. The expression of RPL37a and RPL41 genes in human nasopharyngeal tissues has not been reported previously. Our findings support earlier suspicions on the existence of NPC-associated RP genes, and indicate their importance in human nasopharyngeal organogenesis.
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