Displaying publications 101 - 120 of 250 in total

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  1. Development of a multiplex PCR assay for rapid identification of Burkholderia pseudomallei, Burkholderia thailandensis, Burkholderia mallei and Burkholderia cepacia complex
    Koh SF, Tay ST, Sermswan R, Wongratanacheewin S, Chua KH, Puthucheary SD
    J Microbiol Methods, 2012 Sep;90(3):305-8.
    PMID: 22705921 DOI: 10.1016/j.mimet.2012.06.002
    We have developed a multiplex PCR assay for rapid identification and differentiation of cultures for Burkholderia pseudomallei, Burkholderia thailandensis, Burkholderia mallei and Burkholderia cepacia complex. The assay is valuable for use in clinical and veterinary laboratories, and in a deployable laboratory during outbreaks.
  2. Interaction between a novel intronic IVS3+172 variant and N29I mutation in PRSS1 gene is associated with pancreatitis in a Malaysian Chinese family
    Chua KH, Puah SM, Chew CH, Wong CH, Goh KL
    Pancreatology, 2011;11(4):441-4.
    PMID: 21952138 DOI: 10.1159/000330943
    Hereditary pancreatitis (HP) is a very rare form of early-onset chronic pancreatitis, which usually begins in childhood with a variable spectrum of severity of disease. HP is commonly caused by variants/mutations in the PRSS1 gene as reported in many studies. Therefore, in this study, we aimed to investigate the possible association of PRSS1 gene variants/mutations in a Malaysian Chinese family with HP.
  3. Fulltext Genetic data for 15 STR loci in a Kadazan-Dusun population from East Malaysia
    Kee BP, Lian LH, Lee PC, Lai TX, Chua KH
    Genet. Mol. Res., 2011;10(2):739-43.
    PMID: 21523653 DOI: 10.4238/vol10-2gmr1064
    Allele frequencies of 15 short tandem repeat (STR) loci, namely D5S818, D7S820, D13S317, D16S539, TH01, TPOX, Penta D, Penta E, D3S1358, D8S1179, D18S51, D21S11, CSF1PO, vWA, and FGA, were determined for 154 individuals from the Kadazan-Dusun tribe, an indigenous population of East Malaysia. All loci were amplified by polymerase chain reaction, using the Powerplex 16 system. Alleles were typed using a gene analyzer and the Genemapper ID software. Various statistical parameters were calculated and the combined power of discrimination for the 15 loci in the population was calculated as 0.999999999999999. These loci are thus, informative and can be used effectively in forensic and genetic studies of this indigenous population.
  4. Association analysis of -429T/C and -374T/A polymorphisms of receptor of advanced glycation end products (RAGE) gene in Malaysian with type 2 diabetic retinopathy
    Ng ZX, Kuppusamy UR, Tajunisah I, Fong KC, Chua KH
    Diabetes Res Clin Pract, 2012 Mar;95(3):372-7.
    PMID: 22154374 DOI: 10.1016/j.diabres.2011.11.005
    Conflicting results have been reported in different populations on the association between two particular RAGE gene polymorphisms (-429T/C and -374T/A) and retinopathy in diabetic patients. Therefore this study was designed to assess the association between both gene polymorphisms with retinopathy in Malaysian diabetic patients. A total of 342 type 2 diabetic patients [171 without retinopathy (DNR) and 171 with retinopathy (DR)] and 235 healthy controls were included in this study. Genomic DNA was obtained from blood samples and the screening for the gene polymorphisms was done using polymerase chain reaction-restriction fragment length polymorphism approach. Overall, the genotype distribution for both polymorphisms was not statistically different (p>0.05) among the control, DNR and DR groups. The -429C minor allele frequency of DR group (12.0%) was not significantly different (p>0.05) when compared to DNR group (16.1%) and healthy controls (11.3%). The -374A allele frequency also did not differ significantly between the control and DNR (p>0.05), control and DR (p>0.05) as well as DNR and DR groups (p>0.05). This is the first study report on RAGE gene polymorphism in Malaysian DR patients. In conclusion, -429T/C and -374T/A polymorphisms in the promoter region of RAGE gene were not associated with Malaysian type 2 DR patients.
  5. Stem cell genes are poorly expressed in chondrocytes from microtic cartilage
    Ishak MF, Chua KH, Asma A, Saim L, Aminuddin BS, Ruszymah BH, et al.
    Int J Pediatr Otorhinolaryngol, 2011 Jun;75(6):835-40.
    PMID: 21543123 DOI: 10.1016/j.ijporl.2011.03.021
    This study was aimed to see the difference between chondrocytes from normal cartilage compared to chondrocytes from microtic cartilage. Specific attentions were to characterize the growth of chondrocytes in terms of cell morphology, growth profile and RT-PCR analysis.
  6. Identification of DLG5 and SLC22A5 gene polymorphisms in Malaysian patients with Crohn's disease
    Chua KH, Lian LH, Kee BP, Thum CM, Lee WS, Hilmi I, et al.
    J Dig Dis, 2011 Dec;12(6):459-66.
    PMID: 22118696 DOI: 10.1111/j.1751-2980.2011.00533.x
    The aim of this study was to investigate the association of DLG5 and SLC22A5 gene polymorphisms with the onset of Crohn's disease (CD) in a Malaysian cohort.
  7. Quorum sensing in Aeromonas species isolated from patients in Malaysia
    Chan KG, Puthucheary SD, Chan XY, Yin WF, Wong CS, Too WS, et al.
    Curr Microbiol, 2011 Jan;62(1):167-72.
    PMID: 20544198 DOI: 10.1007/s00284-010-9689-z
    Bacterial quorum sensing signal molecules called N-acylhomoserine lactone (AHL) controls the expression of virulence determinants in many Gram-negative bacteria. We determined AHL production in 22 Aeromonas strains isolated from various infected sites from patients (bile, blood, peritoneal fluid, pus, stool and urine). All isolates produced the two principal AHLs, N-butanoylhomoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL). Ten isolates also produced additional AHLs. This report is the first documentation of Aeromonas sobria producing C6-HSL and two additional AHLs with N-acyl side chain longer than C(6). Our data provides a better understanding of the mechanism(s) of this environmental bacterium emerging as a human pathogen.
  8. Value of human amniotic epithelial cells in tissue engineering for cornea
    Fatimah SS, Ng SL, Chua KH, Hayati AR, Tan AE, Tan GC
    Hum. Cell, 2010 Nov;23(4):141-51.
    PMID: 21166885 DOI: 10.1111/j.1749-0774.2010.00096.x
    Human amniotic epithelial cells (hAECs) are potentially one of the key players in tissue engineering due to their easy availability. The aim of the present study was to develop an optimal isolation and transportation technique, as well as to determine the immunophenotype and epithelial gene expression of hAECs. Amnion was mechanically peeled off from the chorion and digested with trypsin-ethylenediaminetetraacetic acid. The isolated hAECs were cultured in medium containing 10 ng/mL epidermal growth factor until P4. The epithelial gene expression, cell surface antigen and protein expression of hAECs were analyzed by quantitative polymerase chain reaction, flow cytometry and immunocytochemistry. hAECs were also cultured in adipogenic, osteogenic and neurogenic induction media. The best cell yield of hAECs was seen in the digestion of 15 pieces of amnion (2 × 2 cm) and isolated 30 min after digestion with trypsin. F12:Dulbecco's modified eagle medium was the best medium for short term storage at 4 °C. hAECs expressed CD9, CD44, CD73 and CD90, and negligibly expressed CD31, CD34, CD45 and CD117. After serial passage, CK3, CK19 and involucrin gene expressions were upregulated, while p63, CK1 and CK14 gene expressions were downregulated. Sustained gene expressions of integrin β1 and CK18 were observed. At initial culture, these cells might have stem-like properties. However, they differentiated after serial passage. Nonetheless, hAECs have epithelial stem cell characteristics and have the potential to differentiate into corneal epithelial cells. Further investigations are still needed to elucidate the mechanism of differentiation involved and to optimize the culture condition for long term in vitro culture.
  9. Fulltext Plasmodium ovale infection in Malaysia: first imported case
    Lim YA, Mahmud R, Chew CH, T T, Chua KH
    Malar J, 2010;9:272.
    PMID: 20929588 DOI: 10.1186/1475-2875-9-272
    BACKGROUND:
    Plasmodium ovale infection is rarely reported in Malaysia. This is the first imported case of P. ovale infection in Malaysia which was initially misdiagnosed as Plasmodium vivax.

    METHODS:
    Peripheral blood sample was first examined by Giemsa-stained microscopy examination and further confirmed using a patented in-house multiplex PCR followed by sequencing.

    RESULTS AND DISCUSSION:
    Initial results from peripheral blood smear examination diagnosed P. vivax infection. However further analysis using a patented in-house multiplex PCR followed by sequencing confirmed the presence of P. ovale. Given that Anopheles maculatus and Anopheles dirus, vectors of P. ovale are found in Malaysia, this finding has significant implication on Malaysia's public health sector.

    CONCLUSIONS:
    The current finding should serve as an alert to epidemiologists, clinicians and laboratory technicians in the possibility of finding P. ovale in Malaysia. P. ovale should be considered in the differential diagnosis of imported malaria cases in Malaysia due to the exponential increase in the number of visitors from P. ovale endemic regions and the long latent period of P. ovale. It is also timely that conventional diagnosis of malaria via microscopy should be coupled with more advanced molecular tools for effective diagnosis.
  10. Human chorion-derived stem cells: changes in stem cell properties during serial passage
    Fariha MM, Chua KH, Tan GC, Tan AE, Hayati AR
    Cytotherapy, 2011 May;13(5):582-93.
    PMID: 21231803 DOI: 10.3109/14653249.2010.549121
    BACKGROUND AIMS: Fetal membrane from human placenta tissue has been described as a potential source of stem cells. Despite abundant literature on amnion stem cells, there are limited studies on the stem cell properties of chorion-derived stem cells.

    METHODS: The main aim was to determine the stemness properties of serial-passaged human chorion-derived stem cells (hCDSC). Quantitative polymerase chain reaction (PCR) was performed to reveal the following stemness gene expression in serial-passaged hCDSC: Oct-4, Sox-2, FGF-4, Rex-1, TERT, Nanog (3), Nestin, FZD-9, ABCG-2 and BST-1. Cell growth rate was evaluated from passage (P) 1 until P5. The colony-forming unit-fibroblast (CFU-F) frequency of P3 and P5 cells and multilineage differentiation potential of P5 cells were determined. The immunophenotype of hCDSC was compared using the surface markers CD9, CD31, CD34, CD44, CD45, CD73, CD90, CD117, HLA-ABC and HLA-DR, -DP and -DQ. Immunostaining for trophoblast markers was done on P0, P1, P3 and P5 cells to detect the contamination of trophoblasts in culture, while chromosomal abnormality was screened by cytogenetic analysis of P5 cells.

    RESULTS: The surface markers for mesenchymal lineage in hCDSC were more highly expressed at P5 compared with P3 and P0, indicating the increased purity of these stem cells after serial passage. Indeed, all the stemness genes except TERT were expressed at P1, P3 and P5 hCDSC. Furthermore, human chorion contained high clonogenic precursors with a 1:30 CFU-F frequency. Successful adipogenic, chondrogenic and osteogenic differentiation demonstrated the multilineage potential of hCDSC. The karyotyping analysis showed hCDSC maintained chromosomal stability after serial passage.

    CONCLUSIONS: hCDSC retain multipotent potential even at later passages, hence are a promising source for cell therapy in the future.

  11. Identification of NOD2/CARD15 mutations in Malaysian patients with Crohn's disease
    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.
  12. GAPDH as housekeeping gene for human skin fibroblast senescent model
    Zainuddin A, Makpol S, Chua KH, Abdul Rahim N, Yusof YA, Ngah WZ
    Med J Malaysia, 2008 Jul;63 Suppl A:73-4.
    PMID: 19024990
    Validation of housekeeping gene is important for accurate quantitation of RNA in real time RT-PCR technique. The purpose of this study was to determine the validity of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as a housekeeping gene for quantitative real time RT-PCR assessment in human skin fibroblast senescent model. The cells were divided into different treatment groups; young (passage 4), senescent (passage 30), treatment with H2O2 and treatment with A-tocotrienol prior to H2O2 treatment. Our results showed that the expression level of GAPDH was constant with different treatment groups. Therefore, we concluded that GAPDH was suitable to be used as housekeeping gene in human skin fibroblast senescent model.
  13. Apoptosis changes and SA-beta galactosidase expression in stress-induced premature senescence (SIPS) model of human skin fibroblasts
    Abdul Rahim N, Makpol S, Chua KH, Yusof YA, Top GM, Ngah WZ
    Med J Malaysia, 2008 Jul;63 Suppl A:71-2.
    PMID: 19024989
    Stress-induced premature senescence (SIPS) model is in vitro model of cellular aging. In this study, apoptosis was evaluated in SIPS model and in replicative senescent fibroblasts. We also compared the activity of senescence-associated beta-galactosidase (SA-beta gal) as a biomarker of cellular aging. Our results suggested that SIPS model and senescent fibroblasts might share similar mechanism of aging and apoptosis pathway.
  14. Derivation of cochlea hair cell for in vitro expansion and characterization
    Ibnubaidah MA, Chua KH, Mazita A, Azida ZN, Aminuddin BS, Ruszymah BH, et al.
    Med J Malaysia, 2008 Jul;63 Suppl A:115-6.
    PMID: 19025012
    A potential cure for hearing loss would be to regenerate hair cells by stimulating cells of the damaged inner ear sensory epithelia to proliferate and differentiate into hair cells. Here, we investigated the possibility to isolate, culture-expand and characterize the cells from the cochlea membrane of adult mice. Our results showed that the cultured cells isolated from mouse cochlea membrane were heterogenous in nature. Morphologically there were epithelial like cells, hair cell like, nerve cell like and fibroblastic cells observed in the culture. The cultured cells were immunopositive for specific hair cell markers including Myosin 7a, Calretinin and Espin.
  15. Ex vivo growth of rabbit bulbar, fornix and palpebral conjunctival epithelia in a serum-free and feeder layer-free culture system
    Nizam MH, Ruszymah BH, Chua KH, Ghafar NA, Hamzah JC
    Med J Malaysia, 2008 Jul;63 Suppl A:111-2.
    PMID: 19025010
    This study was conducted to explore the feasibility of culturing conjunctiva epithelial cells in serum-free and feeder layer-free culture system with regard to the cell morphology and immunocytochemistry of the rabbit bulbar, fornix and palpebral conjunctiva epithelia. The results showed that epithelium cells from all the three conjunctiva regions can be cultured in a serum-free and feeder layer-free environment. We obtained highest epithelial growth from fornix region with minimum invasion of fibroblast cells compared to other area. All cultured cells were stained positive for cytokeratin 19 and MUC5AC and negative for cytokeratin 3. These findings suggested that fornix was a better source of cells for the development of tissue engineered conjunctiva for future clinical application.
  16. Augmentation of angiogenic and endothelial associated gene expression by EDM50 in human chorion-derived stem cells
    Manzor NF, Chua KH, Tan GC, Tan AE, Abdul Rahman H
    Med J Malaysia, 2008 Jul;63 Suppl A:11-2.
    PMID: 19024960
    The objective of this study was to investigate the angiogenic potential of human chorion-derived stem cells (CDSC) cultured in medium containing bFGF and VEGF (EDM50). Total RNA was extracted from cells cultured in FD+10% FBS and EDM50. Quantitative RT-PCR was carried out to score the differential mRNA expression of genes involve in angiogenesis and endothelial differentiation. Our finding demonstrated that all angiogenic and endothelial associated genes were expressed higher in EDM50. Expression level of ANG-1, eNOS and VEGFR2 were significantly higher in EDM50 compared to FD+10% FBS. Our results suggested that human CDSC cultured in EDM50 can be used for angiogenesis purpose in regenerative medicine.
  17. Differential gene expression of human adipose-derived stem cells in osteogenic induction
    Hamid AA, Ruszymah BH, Aminuddin BS, Sathappan S, Chua KH
    Med J Malaysia, 2008 Jul;63 Suppl A:9-10.
    PMID: 19024959
    Human adipose-derived stem cells (HADSC) have demonstrated the capacity of differentiating into bone depending on the specific induction stimuli and growth factors. However, investigation on stem cell characteristic after osteogenic differentiation is still lacking. The goal of this study was to investigate the differential expression of sternness and osteogenic genes in non-induced HADSC compared with HADSC after osteogenic induction using quantitative Real Time RT-PCR. Our results showed that OCT-4, REX-1, FZD9, OSC, RUNX, and ALP were up regulated after osteogenic induction. This may indicated that HADSCs after osteogenic induction still possessed some stemness properties.
  18. The stemness gene expression of cultured human amniotic epithelial cells in serial passages
    Simat SF, Chua KH, Abdul Rahman H, Tan AE, Tan GC
    Med J Malaysia, 2008 Jul;63 Suppl A:53-4.
    PMID: 19024980
    The aim of the study is to evaluate the stemness gene expression of cultured human amniotic epithelial cells (HAECs) in serial passages. HAECs obtained from human term placentae were cultured in F12:DMEM(1:1) + 10% FBS +10ng/ml EGF in serial passages (P0, P1, P2 and P4). Quantitative RT-PCR was used to assess the gene expression analysis. The results showed that cultured HAECs expressed and downregulated the stemness genes expression for Oct-4, Sox-2, Nanog3, FGF4, Rex-1, FZD-9, BST-1 ABCG2. However, vimentin and nestin gene expression were upregulated. The results suggested that cultured HAECs may have pluripotent and multipotent properties.
  19. Quantitative RT PCR approach to evaluate the neurogenic and gliagenic gene expression of cultured human amniotic epithelial cells
    Tan GC, Simat SF, Abdul Rahman H, Tan AE, Chua KH
    Med J Malaysia, 2008 Jul;63 Suppl A:51-2.
    PMID: 19024979
    The aim of the study is to determine the neuronal and glial gene expression of cultured human amniotic epithelial cells (HAECs) in serial passages. HAECs obtained from human term placentae were cultured in F12:DMEM (1:1) + 10% FBS +10ng/ml EGF in serial passages. Quantitative RT-PCR was used to assess the gene expression analysis. The results showed that the cultured HAECs expressed the neural stem cell genes (Nestin, NSE and Vimentin), mature neuronal genes (TH, MAP-2, beta-III-tubulin and NFM) and glial genes (CNPase, MBP and Olig). These neural stem cell genes increased with serial passages while the genes expression for mature neuronal and glial cells were downregulated. These results suggested that HAECs may promote or involve in neurogenesis and gliagenesis.
  20. Upregulation of SOX-2, FZD9, Nestin, OCT-4 and FGF-4 expression in human chorion derived-stem cells after angiogenic induction
    Abdul Rahman H, Manzor NF, Tan GC, Tan AE, Chua KH
    Med J Malaysia, 2008 Jul;63 Suppl A:57-8.
    PMID: 19024982
    Angiogenic induction was made to promote angiogenesis by differentiating stem cells towards endothelial cells. However, the stemness property of induced cells has not been revealed yet. Hence, we aim to evaluate the differential mRNA expression of stemness genes in human chorion-derived stem cells (CDSC) after being cultured in EDM50 comprised bFGF and VEGF. Results indicated that CDSC cultured in EMD50 expressed significantly higher mRNA level of Sox-2, FZD9, BST-1 and Nestin. In addition Oct-4, FGF-4 and ABCG-2 were also upregulated. Our finding suggested that CDSC after angiogenic induction enhanced its stem cell properties. This could be contributed for the mechanism of stem cell therapy in ischemic problem.
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