Displaying publications 1 - 20 of 108 in total

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  1. Neo CB, Cheah YK, Chin PW, Tan TV, Wong NC, Yap LM, et al.
    Med J Malaysia, 1987 Dec;42(4):294-8.
    PMID: 3454401
    About two-thirds (67.6%) of 142 Ibans (from birth to 90 years of age) from 26 house-holds in a longhouse in Nanga Atoi in the Second Division of Sarawak were infected with intestinal parasites. The more common helmintic infections were hookworms (47.2%) and Trichuris trichiura (43.0%). Intestinal protozoan infections were less common. Single helmintic infections were more common than multiple infections and the commonest type of multiple infections was Trichuris mixed with hookworms. Malaria and filariasis were not reported among these inhabitants surveyed.
  2. Lum LC, Thong MK, Cheah YK, Lam SK
    Ann Trop Paediatr, 1995 Dec;15(4):335-9.
    PMID: 8687212 DOI: 10.1080/02724936.1995.11747794
    In dengue shock syndrome, an acute increase in capillary permeability results in leakage of plasma into the interstitial space. Pleural effusion is commonly seen in dengue shock syndrome. We report three cases of dengue-associated adult respiratory distress syndrome (ARDS) in children, in all of whom dengue haemorrhagic fever, presenting with grade 3 or grade 4 dengue shock syndrome with disseminated intravascular coagulopathy, was confirmed. The criteria for the diagnosis of ARDS were based on the expanded definition of ARDS by Murray et al. Treatment consisted of fluid resuscitation, correction of coagulopathy and mechanical ventilation. All three children had multi-organ impairment, but it was more severe in the two who died. The one survivor was well at discharge.
  3. Wan KF, Radu S, Cheah YK, Benjamin PG, Ling CM, Hon SF, et al.
    PMID: 15115139
    Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea among infants in developing countries. A total of 38 EPEC isolates, obtained from diarrhea patients of Hospital Miri, Sarawak, were investigated through plasmid profile, antibiotic resistance and randomly amplified polymorphic DNA (RAPD) analysis. From the 8 types of antibiotics used, all isolates were 100% resistant to furoxime, cephalothin and sulphamethoxazole and showed high multiple antibiotic resistant (MAR) indexes, ranging from 0.5 to 1.0. In plasmid profiling, 22 isolates (58%) showed the presence of one or more plasmids in the range 1.0 to 30.9 mDa. The dendrogram obtained from the results of the RAPD-PCR discriminated the isolates into 30 single isolates and 3 clusters at the level of 40% similarity. The EPEC isolates were highly diverse, as shown by their differing plasmid profiles, antibiotic resistance patterns and RAPD profiles.
  4. William JL, Radu S, Aziz SA, Rahim RA, Cheah YK, Liwan A, et al.
    Br J Sports Med, 2004 Feb;38(1):12-4.
    PMID: 14751938
    BACKGROUND: Research has shown that athletes are carriers of Staphylococcus aureus during physical activity.
    OBJECTIVE: To estimate the mean total plate count of S aureus carried by footballers before and after training at an indoor venue.
    METHODS: Forty Malay and 20 Indian students volunteered to participate. There was also a control group consisting of 40 Malay and 20 Indian students who were not active. The experimental group were active footballers who had played at school or club level. The subjects were healthy and free of skin infection. The experiment was divided into three sessions, with 20 subjects present at each. At each session, the subjects trained for one hour. Swabs were taken from the skin, nose, and ear before and after training. For the control group, swabs were taken only once from the skin, nose, and ear. The swabs were subjected to biochemical tests and then streaked and cultured aerobically in Baird Parker agar plates for 24 hours at 37 degrees C. Black colonies with a clear zone were presumed to be S aureus, and the mean total plate count of the colonies was estimated. Gram staining, catalase, coagulase slide, coagulase tube, acetoin production, o-nitrophenyl beta-D-galactopyranoside (ONPG), and mannitol fermentation tests were used to confirm the colonies as S aureus. A haemolysin test was conducted with human blood to confirm haemolytic activity.
    RESULTS: All subjects in the experimental group were carrying S aureus both before and after training. The estimated mean total counts of colonies from the skin, ear, and nose for the Malays before training were 33, 71, and 312 respectively. Counts after training were 21, 44, and 452 respectively. The results for the Indians were 72, 80, and 309 respectively before training and 55, 200, and 466 respectively after training. The positive results for Gram staining, catalase, coagulase slide, coagulase tube, acetoin production, ONPG, and mannitol fermentation tests were 100%, 96%, 95%, 95%, 93%, 93%, and 90% respectively. All subjects in the control group were also carrying S aureus.
    CONCLUSIONS: All of the players were carriers of S aureus during training. The decrease in total count from the skin for both races may be due to lysozyme activity lysing the bacterial cells. Contamination of the environment with these bacteria may have increased the estimated total plate count in the nose. The experimental group face a higher risk of infection because of lower immunity during training and higher rate of injuries compared with the control group.
  5. Khoo CH, Cheah YK, Lee LH, Sim JH, Salleh NA, Sidik SM, et al.
    Antonie Van Leeuwenhoek, 2009 Nov;96(4):441-57.
    PMID: 19565351 DOI: 10.1007/s10482-009-9358-z
    The increased occurrence of Salmonella occurrence in local indigenous vegetables and poultry meat can be a potential health hazards. This study is aimed to detect the prevalence of twenty different virulence factors among Salmonella enterica strains isolated from poultry and local indigenous vegetables in Malaysia via an optimized, rapid and specific multiplex PCR assay. The assay encompasses a total of 19 Salmonella pathogenicity islands genes and a quorum sensing gene (sdiA) in three multiplex reaction sets. A total of 114 Salmonella enterica isolates belonging to 38 different serovars were tested. Each isolate in under this study was found to possess up to 70% of the virulence genes tested and exhibited variable pathogenicity gene patterns. Reproducibility of the multiplex PCR assay was found to be 100% and the detection limit of the optimized multiplex PCR was tested with lowest detectable concentration of DNA 0.8 pg microl(-1). This study demonstrated various Salmonella pathogenicity island virulence gene patterns even within the same serovar. This sets of multiplex PCR system provide a fast and reliable typing approach based on Salmonella pathogenicity islands, thus enabling an effective monitoring of emerging pathogenic Salmonella strains as an additional tool in Salmonella surveillance studies.
  6. Tham CL, Liew CY, Lam KW, Mohamad AS, Kim MK, Cheah YK, et al.
    Eur J Pharmacol, 2010 Feb 25;628(1-3):247-54.
    PMID: 19958764 DOI: 10.1016/j.ejphar.2009.11.053
    Curcumin is a highly pleiotropic molecule with significant regulatory effects upon inflammation and inflammatory related diseases. However curcumin has one major important limitation in which it has poor bioavailability. Design of synthetic structural derivatives of curcumin is but one approach that has been used to overcome its poor bioavailability while retaining, or further enhancing, its drug-like effects. We have synthesized a series of curcumin analogues and describe the effects of 2,6-bis-4-(hydroxyl-3-methoxy-benzylidine)-cyclohexanone or BHMC upon nitric oxide and cytokine synthesis in cellular models of inflammation. BHMC showed a significant dose-response inhibitory action upon the synthesis of NO and we have shown that this effect was due to suppression of both iNOS gene and enzyme expression without any effects upon scavenging of nitrite. We also demonstrated that BHMC has a very minimal effect upon iNOS activity with no effect at all upon the secretion of PGE(2) but has a strong inhibitory effect upon MCP-1 and IL-10 secretion and gene expression. Secretion and gene expression of TNF-alpha and IL-6 were moderately inhibited whereas IL-8 and IL-1beta were not altered. We conclude that BHMC selectively inhibits the synthesis of several inflammatory mediators. BHMC should be considered a promising drug lead for preclinical and further pharmacological studies.
  7. Sim JH, Khoo CH, Lee LH, Cheah YK
    J Microbiol Biotechnol, 2010 Apr;20(4):651-8.
    PMID: 20467234
    Garcinia is commonly found in Malaysia, but limited information is available regarding endophytic fungi associated with this plant. In this study, 24 endophytic fungi were successfully recovered from different parts of two Garcinia species. Characterization of endophytic fungi was performed based on the conserved internal transcribed spacer (ITS) region sequence analysis and the antimicrobial properties. Results revealed that fruits of the plant appeared to be the highest inhabitation site (38 %) as compared with others. Glomerella sp., Guignardia sp., and Phomopsis sp. appeared to be the predominant endophytic fungi group in Garcinia mangostana and Garcinia parvifolia. Phylogenetic relationships of the isolated endophytic fungi were estimated from the sequences of the ITS region. On the other hand, antibacterial screening showed 11 of the isolates possessed positive response towards pathogenic and nonpathogenic bacteria. However, there was no direct association between certain antibacterial properties with the specific genus observed.
  8. Edwin Shiaw CS, Shiran MS, Cheah YK, Tan GC, Sabariah AR
    Med J Malaysia, 2010 Jun;65(2):133-7.
    PMID: 23756798 MyJurnal
    This study was done to evaluate various DNA and RNA extractions from archival FFPE tissues. A total of 30 FFPE blocks from the years of 2004 to 2006 were assessed with each modified and adapted method. Extraction protocols evaluated include the modified enzymatic extraction method (Method A), Chelex-100 extraction method (Method B), heat-induced retrieval in alkaline solution extraction method (Methods C and D) and one commercial FFPE DNA Extraction kit (Qiagen, Crawley, UK). For RNA extraction, 2 extraction protocols were evaluated including the enzymatic extraction method (Method 1), and Chelex-100 RNA extraction method (Method 2). Results show that the modified enzymatic extraction method (Method A) is an efficient DNA extraction protocol, while for RNA extraction, the enzymatic method (Method 1) and the Chelex-100 RNA extraction method (Method 2) are equally efficient RNA extraction protocols.
  9. Liew CY, Tham CL, Lam KW, Mohamad AS, Kim MK, Cheah YK, et al.
    Immunopharmacol Immunotoxicol, 2010 Sep;32(3):495-506.
    PMID: 20109039 DOI: 10.3109/08923970903575708
    HMP [3-(2-hydroxyphenyl)-1-(5-methyl-furan-2-y-l) propenone] was evaluated for its ability to inhibit the synthesis of major proinflammatory mediators and cytokines in interferon-gamma (IFN-gamma)- and lipopolysaccharide (LPS)-induced RAW 264.7 cells and phorbol myristate acetate (PMA)-differentiated/LPS-induced U937 cells. HMP suppressed the production of nitric oxide (NO) with significant inhibitory effects at doses as low as 0.78 microM (P < 0.05). Prostaglandin E2 (PGE2) secretion was also inhibited at doses of 12.5 microM and above (P < 0.01). The secretion of both TNF-alpha and IL-6 were only inhibited at the highest dose used (25 microM; P < 0.001). IL-1beta secretion was also inhibited from 12.5 microM onwards (P < 0.01). This inhibition was demonstrated to be caused by down-regulation of inducible enzymes, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), without direct effect upon iNOS or COX-2 enzyme activity. HMP only inhibited iNOS (P < 0.001) and IL-1beta (P < 0.05) gene expression at the highest tested concentration. HMP did not affect the secretion of chemokines IL-8 and monocyte chemotactic protein-1 (MCP-1) and the anti-inflammatory cytokine IL-10. The most striking effect of HMP was its NO inhibitory activity and therefore we conclude that HMP is a selective inhibitor of iNOS.
  10. Liew CY, Lam KW, Kim MK, Harith HH, Tham CL, Cheah YK, et al.
    Int Immunopharmacol, 2011 Jan;11(1):85-95.
    PMID: 21035434 DOI: 10.1016/j.intimp.2010.10.011
    We previously showed that 3-(2-hydroxyphenyl)-1-(5-methyl-furan-2-y-l)propenone (HMP), suppressed the synthesis of various proinflammatory mediators. In this study, HMP showed a dose-dependent inhibition of NO synthesis in the RAW 264.7 murine macrophage line. The inhibition of NO synthesis was related to inhibition of p38 phosphorylation and kinase activity that led to significant inhibition of phosphorylation of ATF-2. This effect in turn caused inhibition of AP-1-DNA binding which partially explains the inhibitory effect upon the synthesis of iNOS. HMP had no effect upon phosphorylation of JNK, ERK1/2 and STAT-1. Kinase activity of JNK and ERK1/2 was also not affected by HMP as determined by levels of phosphorylated c-jun and phosphorylated elk-1. Furthermore HMP failed to block phosphorylation of IκBα, and subsequent nuclear translocation and DNA-binding activity of p65 NF-κB in IFN-γ/LPS-induced RAW 264.7 cells. Molecular docking experiments confirmed that HMP fits well in the highly conserved hydrophobic pocket of p38 MAP kinase. We conclude that the synthetic HMP is a chalcone analogue that selectively inhibits the p38/ATF-2 and AP-1 signaling pathways in the NO synthesis by the macrophage RAW 264.7.
  11. Tham CL, Lam KW, Rajajendram R, Cheah YK, Sulaiman MR, Lajis NH, et al.
    Eur J Pharmacol, 2011 Feb 10;652(1-3):136-44.
    PMID: 21114991 DOI: 10.1016/j.ejphar.2010.10.092
    We previously showed that 2,6-bis-(4-hydroxyl-3-methoxybenzylidine)cyclohexanone (BHMC), suppressed the synthesis of various proinflammatory mediators. In this study we explain the mechanism of action of BHMC in lipopolysaccharide (LPS)-induced U937 monocytes and further show that BHMC prevents lethality of CLP-induced sepsis. BHMC showed dose-dependent inhibitory effects on p38, JNK and ERK 1/2 activity as determined by inhibition of phosphorylation of downstream transcription factors ATF-2, c-Jun and Elk-1 respectively. Inhibition of these transcription factors subsequently caused total abolishment of AP-1-DNA binding. BHMC inhibited p65 NF-κB nuclear translocation and DNA binding of p65 NF-κB only at the highest concentration used (12.5μM) but failed to alter phosphorylation of JNK, ERK1/2 and STAT-1. Since the inhibition of p38 activity was more pronounced we evaluated the possibility that BHMC may bind to p38. Molecular docking experiments confirmed that BHMC fits well in the highly conserved hydrophobic pocket of p38 MAP kinase. We also show that BHMC was able to improve survival from lethal sepsis in a murine caecal-ligation and puncture (CLP) model.
  12. Pui CF, Wong WC, Chai LC, Lee HY, Noorlis A, Zainazor TC, et al.
    Trop Med Health, 2011 Mar;39(1):9-15.
    PMID: 22028607 DOI: 10.2149/tmh.2010-20
    Salmonellosis outbreaks involving typhoid fever and human gastroenteritis are important diseases in tropical countries where hygienic conditions are often not maintained. A rapid and sensitive method to detect Salmonella spp., Salmonella Typhi and Salmonella Typhimurium is needed to improve control and surveillance of typhoid fever and Salmonella gastroenteritis. Our objective was the concurrent detection and differentiation of these food-borne pathogens using a multiplex PCR. We therefore designed and optimized a multiplex PCR using three specific PCR primer pairs for the simultaneous detection of these pathogens. The concentration of each of the primer pairs, magnesium chloride concentration, and primer annealing temperature were optimized before verification of the specificity of the primer pairs. The target genes produced amplicons at 429 bp, 300 bp and 620 bp which were shown to be 100% specific to each target bacterium, Salmonella spp., Salmonella Typhi and Salmonella Typhimurium, respectively.
  13. Anarjan N, Tan CP, Ling TC, Lye KL, Malmiri HJ, Nehdi IA, et al.
    J Agric Food Chem, 2011 Aug 24;59(16):8733-41.
    PMID: 21726079 DOI: 10.1021/jf201314u
    A simplex centroid mixture design was used to study the interactions between two chosen solvents, dichloromethane (DCM) and acetone (ACT), as organic-phase components in the formation and physicochemical characterization and cellular uptake of astaxanthin nanodispersions produced using precipitation and condensation processes. Full cubic or quadratic regression models with acceptable determination coefficients were obtained for all of the studied responses. Multiple-response optimization predicted that the organic phase with 38% (w/w) DCM and 62% (w/w) ACT yielded astaxanthin nanodispersions with the minimum particle size (106 nm), polydispersity index (0.191), and total astaxanthin loss (12.7%, w/w) and the maximum cellular uptake (2981 fmol/cell). Astaxanthin cellular uptake from the produced nanodispersions also showed a good correlation with their particle size distributions and astaxanthin trans/cis isomerization ratios. The absence of significant (p > 0.05) differences between the experimental and predicted values of the response variables confirmed the adequacy of the fitted models.
  14. Lee HY, Chai LC, Pui CF, Wong WC, Mustafa S, Cheah YK, et al.
    J Microbiol Biotechnol, 2011 Sep;21(9):954-9.
    PMID: 21952372
    There have been a number of studies conducted in order to compare the efficiencies of recovery rates, utilizing different protocols, for the isolation of L. monocytogenes. However, the severity of multiple cell injury has not been included in these studies. In the current study, L. monocytogenes ATCC 19112 was injured by exposure to extreme temperatures (60°C and -20°C) for a one-step injury, and for a two-step injury the cells were transferred directly from a heat treatment to frozen state to induce a severe cell injury (up to 100% injury). The injured cells were then subjected to the US Food and Drug Administration (FDA), the ISO-11290, and the modified United States Department of Agriculture (mUSDA) protocols, and plated on TSAyeast (0.6% yeast), PALCAM agar, and CHROMAgar Listeria for 24 h or 48 h. The evaluation of the total recovery of injured cells was also calculated based on the costs involved in the preparation of media for each protocol. Results indicate that the mUSDA method is best able to aid the recovery of heat-injured, freeze-injured, and heat-freeze-injured cells and was shown to be the most cost effective for heat-freeze-injured cells.
  15. Cheah YK
    Malays J Nutr, 2011 Dec;17(3):385-91.
    PMID: 22655460 MyJurnal
    Given the importance of physical activity to health, this study investigated the socio-demographic determinants of physical activity participation in a sample of adults in Penang.
  16. Lee CM, Sieo CC, Cheah YK, Abdullah N, Ho YW
    J Sci Food Agric, 2012 Feb;92(3):660-6.
    PMID: 21919004 DOI: 10.1002/jsfa.4627
    Four repetitive element sequence-based polymerase chain reaction (rep-PCR) methods, namely repetitive extragenic palindromic PCR (REP-PCR), enterobacterial repetitive intergenic consensus PCR (ERIC-PCR), polytrinucleotide (GTG)₅ -PCR and BOX-PCR, were evaluated for the molecular differentiation of 12 probiotic Lactobacillus strains previously isolated from the gastrointestinal tract of chickens and used as a multistrain probiotic. This study represents the first analysis of the comparative efficacy of these four rep-PCR methods and their combination (composite rep-PCR) in the molecular typing of Lactobacillus strains based on a discriminatory index (D).
  17. Lee LH, Cheah YK, Mohd Sidik S, Ab Mutalib NS, Tang YL, Lin HP, et al.
    World J Microbiol Biotechnol, 2012 May;28(5):2125-37.
    PMID: 22806035 DOI: 10.1007/s11274-012-1018-1
    The present study aimed to isolate actinobacteria from soil samples and characterized them using molecular tools and screened their secondary metabolites for antimicrobial activities. Thirty-nine strains from four different location of Barrientos Island, Antarctica using 12 types of isolation media was isolated. The isolates were preceded to screening of secondary metabolites for antimicrobial and antifungal activities. Using high-throughput screening methods, 38% (15/39) of isolates produced bioactive metabolites. Approximately 18% (7/39), 18% (7/39), 10% (4/39) and 2.5% (1/39) of isolates inhibited growth of Candida albicans ATCC 10231(T), Staphylococcus aurues ATCC 51650(T), methicillin-resistant Staphylococcus aurues (MRSA) ATCC BAA-44(T) and Pseudomonas aeruginosa ATCC 10145(T), respectively. Molecular characterization techniques like 16S rRNA analysis, Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR), Random amplified polymorphic DNA (RAPD) and composite analyses were used to characterize the actinobacteria strains. Analysis of 16S rRNA sequences is still one of the most powerful methods to determine higher taxonomic relationships of Actinobacteria. Both RAPD and ERIC-PCR fingerprinting have shown good discriminatory capability but RAPD proved to be better in discriminatory power than ERIC-PCR. Our results demonstrated that composite analysis of both fingerprinting generally increased the discrimination ability and generated best clustering for actinobacteria strains in this study.
  18. Poh LW, Rukman AW, Cheah YK, Norital Z, Nazri AM, Mariana NS
    Med J Malaysia, 2012 Dec;67(6):639-40.
    PMID: 23770967 MyJurnal
    Vancomycin-resistant Enterococcus faecium (VREF) in human infections mostly belong to the high-risk, epidemic, clonal complex-17 (CC17) group. Treatment limitation and high conjugation frequency makes it dominant in hospitals worldwide. We investigated positive cultures by Pulse-field gel electrophoresis (PFGE), multi locus sequence typing (MLST). DNA of two strains (A2 and C) appeared to be clonally related by PFGE. Three strains were of ST 18 type (A1, B and C) and strain A2 is of a new ST 596. This ST 18 type strain found in our study is crucial and is believed to be the first in Malaysia.
  19. Shah AH, Saleha AA, Zunita Z, Cheah YK, Murugaiyah M, Korejo NA
    Vet Microbiol, 2012 Dec 7;160(3-4):355-61.
    PMID: 22739058 DOI: 10.1016/j.vetmic.2012.05.037
    Arcobacter is getting more attention due to its detection from wide host-range and foods of animal origin. The objective of this study was to determine the prevalence of Arcobacter spp. in various sources at farm level and beef retailed in markets in Malaysia and to assess the genetic relatedness among them. A total of 273 samples from dairy cattle including cattle (n=120), floor (n=30), water (n=18) and milk (n=105) as well as 148 beef samples collected from retail markets were studied. The overall prevalence of Arcobacter in various sources was 15% (63/421). However, source-wise detection rate of Arcobacter spp. was recorded as 26.66% (8/30) in floor, 26.3% (39/148) in beef, 11.11% (2/18) in water, 7.6% (8/105) in milk and 6.66% (8/120) in cattle. Arcobacter butzleri was the frequently isolated species however, a total of 75%, 66.7%, 53.8%, 50% and 12.5%% samples from floor, milk, beef, water and cattle, respectively, were carrying more than one species simultaneously. One (12.5%) cattle and beef sample (2.5%) found to be carrying one Arcobacter spp., A. skirrowii, only. Typing of Arcobacter isolates was done though pulsed field gel electrophoresis (PFGE) after digested with Eag1 restriction endonuclease (RE). Digestion of genomic DNA of Arcobacter from various sources yielded 12 major clusters (≥ 50% similarity) which included 29 different band patterns. A number of closely related A. butzleri isolates were found from beef samples which indicate cross contamination of common type of Arcobacter. Fecal shedding of Arcobacter by healthy animals can contaminate water and milk which may act as source of infection in humans.
  20. Lee LH, Cheah YK, Nurul Syakima AM, Shiran MS, Tang YL, Lin HP, et al.
    Genet. Mol. Res., 2012;11(2):1627-41.
    PMID: 22782582 DOI: 10.4238/2012.June.15.12
    Fifty-seven proteobacterium species were successfully isolated from soils of Barrientos Island of the Antarctic using 11 different isolation media. Analysis of 16S rDNA sequencing of these isolates showed that they belonged to eight different genera, namely Bradyrhizobium, Sphingomonas, Methylobacterium, Caulobacter, Paracoccus, Ralstonia, Rhizobium, and Staphylococcus. All isolates were studied for capability of producing antimicrobial and antifungal secondary metabolites using high-throughput screening models. Approximately 23 (13/57) and 2% (1/57) of isolates inhibited growth of Candida albicans ATCC 10231(T) and Staphylococcus aureus ATCC 51650(T), respectively. These results indicated that proteobacterium species isolates from Antarctic could serve as potential source of useful bioactive metabolites. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting produced nine clusters and 13 single isolates, with a high D value of 0.9248. RAPD fingerprinting produced six clusters and 13 single isolates, with a relatively low D value of 0.7776. ERIC-PCR analysis proved to have better discrimination capability than RAPD analysis and generated better clustering for all proteobacterium species isolates. We conclude that ERIC-PCR is a robust, reliable and rapid molecular typing method for discriminating different genera of proteobacteria.
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