Displaying publications 1 - 20 of 149 in total

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  1. Chua KB
    Med J Malaysia, 2010 Dec;65(4):277-82.
    PMID: 21901945 MyJurnal
    This is a retrospective cross-sectional study based on the database of clusters of patients with clinical diagnosis of chikungunya (CHIK) that were referred to the National Public Health Laboratory for diagnostic investigations from January 2006 to December 2009. Of the 13,759 referred patients, a total of 6314 (45.9%) patients were laboratory confirmed to have CHIK and 7445 (54.1) patients were considered as clinical cases of CHIK by epidemiological link. Epidemic curves plotted using date of onset of illness for all referred clusters of cases showed that there were three unrelated outbreaks of CHIK in Malaysia from 2006 to 2009. There were two small outbreaks that occurred within the state of Perak in 2006. The cluster of cases in 2008 and 2009 were of related outbreak which started in Johor state and subsequently spread to various parts of Malaysia. The mean age of the patients was 37.0 years old and those patients in the laboratory confirmed group were significantly younger than those in the epidemiological linked group. The main presenting clinical features recorded in this study were fever, arthralgia, myalgia and rashes. Those patients in the laboratory confirmed group had a significant higher incidence of fever, arthralgia and rash than those in the epidemiological linked group.
  2. Chua KB
    Malays J Pathol, 2010 Dec;32(2):75-80.
    PMID: 21329177 MyJurnal
    An outbreak of acute febrile encephalitis affecting pig-farm workers and owners was recognized in peninsular Malaysia as early as September 1998. The outbreak was initially thought to be due to Japanese encephalitis (JE) virus and thus very intensive prevention, control and communication strategies directed at JE virus were undertaken by the Ministry of Health and Ministry of Agriculture of Malaysia. There was an immediate change in the prevention, control and communication strategies with focus and strategies on infected pigs as the source of infections for humans and other animals following the discovery of Nipah virus. Information and understanding the risks of Nipah virus infections and modes of transmission strengthened the directions of prevention, control and communication strategies. A number of epidemiological surveillances and field investigations which were broadly divided into 3 groups covering human health sector, animal health sector and reservoir hosts were carried out as forms of risk assessment to determine and assess the factors and degree of risk of infections by the virus. Data showed that there was significant association between Nipah virus infection and performing activities involving close contact with pigs, such as processing of piglets, administering injection or medication to pigs, assisting in the birth of piglets, assisting in pig breeding, and handling of dead pigs in the affected farms. A complex process of anthropogenic driven deforestation, climatic changes brought on by El Niño-related drought, forest fire and severe haze, and ecological factors of mixed agro-pig farming practices and design of pig-sties led to the spillovers of the virus from its wildlife reservoir into pig population.
  3. Chua KB
    Malays J Pathol, 2010 Dec;32(2):69-73.
    PMID: 21329176 MyJurnal
    The outbreak of Nipah virus, affecting pigs and pig-farm workers, was first noted in September 1998 in the north-western part of peninsular Malaysia. By March 1999, the outbreak had spread to other pig-farming areas of the country, inclusive of the neighbouring country, Singapore. A total of 283 human cases of viral encephalitis with 109 deaths were recorded in Malaysia from 29 September 1998 to December 1999. During the outbreak period, a number of surveillances under three broad groups; Surveillance in Human Health Sector, Surveillance in Animal Health Sector, and Surveillance for the Reservoir Hosts, were carried out to determine the prevalence, risk of virus infections and transmission in human and swine populations as well as the source and reservoir hosts of Nipah virus. Surveillance data showed that the virus spread rapidly among pigs within infected farms and transmission was attributed to direct contact with infective excretions and secretions. The spread of the virus among pig farms within and between states of peninsular Malaysia was due to movement of pigs. The transmission of the virus to humans was through close contact with infected pigs. Human to human transmission was considered a rare event though the Nipah virus could be isolated from saliva, urine, nasal and pharyngeal secretions of patients. Field investigations identified fruitbats of the Pteropid species as the natural reservoir hosts of the viruses. The outbreak was effectively brought under control following the discovery of the virus and institution of correct control measures through a combined effort of multi-ministerial and multidisciplinary teams working in close co-operation and collaboration with other international agencies.
  4. Chua KB
    Med J Malaysia, 1999 Mar;54(1):58-64.
    PMID: 10972006
    A 10-year follow-up of children having exanthem subitum (ES) seen in an outpatient paediatric clinic, Kuala Lumpur, Malaysia shows that uvulo-palatoglossal junctional (UPJ) ulcer is a reliable early clinical sign of ES. During this period, 1,977 children (1,086 males, 891 females) had adequate follow-up from the age of 3 months to 24 months old. 897 children (478 males, 419 females) were noted to have UPJ ulcers. Of these 897 children, 855 (459 males, 396 females) presented with the classical clinical features of ES of maculopapular rash following 3 to 4 days of fever. The positive predictive value and the negative predictive value of UPJ ulcers in the clinical diagnosis of ES are 95.3% and 100% respectively. Among the 855 children with clinical features of ES, a provisional diagnosis of ES could be made in 781 children during the pre-eruptive phase by the presence of the UPJ ulcers. The other 74 children already had the rash at the time of consultation at the clinic. The peak age of occurrence of ES was 6 months old with 98.2% of the total cases of ES seen between the age of 4 and 12 months. There was no significant gender difference in the incidence of ES nor any seasonal variation. Mild to moderate diarrhoea was the other commonly associated clinical feature which usually presented from the third febrile day onwards.
    Study site: Paediatric clinic, Assunta Hospital, Petaling Jaya, Selangor, Malaysia
  5. Hamoud, H. A., Ruszymah, I., Chua, K. H., Aminuddin, S
    Medicine & Health, 2017;12(2):293-303.
    MyJurnal
    Kejuruteraan tisu merupakan satu bidang perubatan baru yang membolehkan tisu
    manusia dibentuk secara in vitro sebelum pemindahan tisu dilakukan. Sel stem
    mesenkima daripada sum sum tulang (BMSCs) adalah sumber sel yang sesuai
    dalam kejuruteraan tisu tulang rawan, ekoran kebolehannya untuk membentuk
    rawan hialin. Kajian ini telah dijalankan untuk mengkaji potensi BMSCs untuk
    membentuk sel rawan secara in vitro dan in vivo. BMSCs dipencilkan daripada
    kambing dan dibahagikan kepada dua kumpulan; iaitu kumpulan kajian dan
    kumpulan kawalan. Sel di dalam kumpulan kawalan disemai di dalam medium
    yang mengandungi 10% serum anak lembu (FBS). Manakala, sel di dalam kumpulan
    kajian telah dikultur di dalam medium yang diperkaya dengan 1% FBS, 1% ITS, 5
    ng/mL TGF-ß3, 50 ng/mL IGF-1, 40 ng/mL L-proline, 100 nM dexamethasone dan
    50 μg / fosfat. Analisis pembentukan sel rawan telah dijalankan secara in vivo pada
    model mencit gondol atimus. Sel didapati beragregasi di dalam kumpulan kajian
    dan menunjukkan permulaannya kondrogenesis telah berlaku dalam pengkulturan
    sel. Kerangka fibrin yang telah disemai bersama sel yang telah atau tidak diaruh
    disediakan dan ditanamkan di dalam lapisan subkutaneus mencik gondol atimus
    selama 5 minggu. Eksplan tersebut kemudiannya dikeluarkan daripada lokasi
    penempelan untuk pemeriksaan histologi. Berdasarkan pewarnaan Safranin O dan
    pengekspresan GAG, eksplan daripada kumpulan kajian didapati menghasilkan
    matriks rawan pada kadar yang tinggi berbanding eksplan di dalam kumpulan
    kawalan. Hasil kajian ini menunjukkan keberkesanan medium rendah serum yang mengandungi TGF-ß3 merangsang pembezaan sel stem mesenkima daripada
    sum-sum tulang untuk menjadi sel rawa
  6. Chua KB, Chua KH, Chua IL, Chen KF
    Malays J Pathol, 2004 Jun;26(1):69-71.
    PMID: 16190110
    Virus isolation and accurate characterization plays a crucial role in the rapid identification of the causative agents of infectious disease outbreaks especially if the causative viruses are novel where no pre-existing diagnostic reagents would be available. A new cell culture tube, named Jui Meng (JM) Cell Culture Tube, was developed to reduce the cost and improve the efficiency and biosafety of work pertaining to virus isolation. The design of the tube is based heavily on the principle of practicability, functionality, biosafety and long-term cost saving for diagnostic laboratory work in virus isolation. It is designed to culture an initial inoculum of one milliliter of culture medium containing 1 x 10(4) to 1 x 10(5) cells/ml.
  7. Ismail SM, Sundar UM, Hui CK, Aminuddin A, Ugusman A
    J Taibah Univ Med Sci, 2018 Jun;13(3):225-231.
    PMID: 31435328 DOI: 10.1016/j.jtumed.2018.01.003
    Objectives: Inflammation plays a key role in the pathogenesis of atherosclerosis. Piper sarmentosum is an herb with antioxidant and anti-atherosclerotic activities. The aim of this study was to evaluate the anti-inflammatory properties of an aqueous extract of P. sarmentosum (AEPS) in human umbilical vein endothelial cells (HUVECs).

    Methods: HUVECs were divided into six groups: control, treatment with 10 ng/ml TNF-α, and co-treatment of 10 ng/ml TNF-α with four different concentrations of AEPS (100, 150, 250, and 300 μg/ml) for 24 h. Subsequently, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) protein expression, U937 monocyte cells adhesion, and nuclear factor-kappaB (NF-κB) p65 expression in HUVECs were measured.

    Results: Treatment of TNF-α-stimulated HUVECs with AEPS at different concentrations resulted in decreased VCAM-1 and ICAM-1 protein expression in a dose-dependent manner. Furthermore, AEPS also inhibited TNF-α-stimulated U937 monocyte cells adhesion to HUVECs. In addition, AEPS reduced TNF-α-induced NF-κB p65 expression in a dose-dependent manner.

    Conclusions: The results indicated that AEPS suppressed TNF-α-induced VCAM-1 and ICAM-1 expression NF-κB signaling.

  8. Chua KB, Chua IL, Chua IE, Chua KH
    Singapore Med J, 2005 Nov;46(11):639-44.
    PMID: 16228097
    Dengue and dengue haemorrhagic fever are common and serious arboviral diseases endemic in a number of countries situated in both the tropical and subtropical belts.
  9. Chua KH, Chai HC
    Genet. Mol. Res., 2012;11(1):636-43.
    PMID: 22535399 DOI: 10.4238/2012.March.16.1
    Hemagglutinin (HA) protein plays an important role in binding the influenza virus to infected cells and therefore mediates infection. Deposited HA sequences of 86 Asian strains of influenza A (H1N1) viruses during the first outbreak were obtained from the NCBI database and compared. Interaction of the HA protein of influenza A (H1N1) virus with the human sialic acid receptor was also studied using bioinformatics. Overall, not more than three single-point amino acid variants/changes were observed in the HA protein region of influenza A (H1N1) virus from Asian countries when a selected group sequence comparison was made. The bioinformatics study showed that the HA protein of influenza A (H1N1) binds to the sialic acid receptor in human airway receptors, possibly key to air-borne infection in humans.
  10. Ang KT, Ruhaini I, Chua KB
    Med J Malaysia, 2006 Aug;61(3):292-5.
    PMID: 17240578 MyJurnal
    Dengue fever is major public health problem especially among the highly urbanized states of Malaysia, such as, Selangor and Kuala Lumpur Federal Territory. We report an epidemiological cluster pattern of dengue outbreak in the district of Gombak, Selangor that may mimic other acute febrile illnesses in which the transmission mode is via close contact. This dengue outbreak consisted of two waves; an initial cluster of three cases (including the first deceased, JI) which occurred between 20th and 21st of July, followed by a later larger cluster of 11 cases that occurred between 1st and 8th of August 2005. This epidemiological clustering pattern of acute dengue virus infection among close contacts suggests an intense rate of dengue virus transmission within the vicinity of the first deceased's house.
  11. Chua KB, Lam SK, AbuBakar S
    Med J Malaysia, 1998 Sep;53(3):296-301.
    PMID: 10968172
    Exanthem subitum (ES) is a common childhood exanthematous disease. In a recent study of ES due to human herpesvirus 6 (HHV 6), we isolated human herpesvirus 7 (HHV 7) from the peripheral blood mononuclear cells (PBMC) of a seven month-old infant with typical symptoms of ES. The identity of the virus was confirmed by indirect immunofluorescence using HHV 7 specific monoclonal antibody and by amplification of the HHV 7 specific genomic sequences using the polymerase chain reaction (PCR). Paired serum samples from the infant showed serological conversion to the isolated virus. The clinical manifestations of ES in this infant appeared to be milder than the classical ES due to HHV 6.
  12. Chua KB, Khairullah NS, Hooi PS
    PMID: 9031408
    Sera from healthy donors and patients stored over a period of 2 years, aged 1 to 83 years, were examined for reactivity to human herpes virus 6 (HHV-6) by the standard indirect immunofluorescence assay (IFA). Of the 600 serum specimens screened, 502 showed positive reactivity to HHV-6. This gives an overall seropositive rate of 83.7%. There is no significant difference in the overall positive rate between the ethnic groups (Chinese, Malays, Indians) (chi 2 = 0.35 df = 2 p > 0.05). However, there is significant difference in the positive rates at the extreme age groups of 1 year as well as 61 years and above. From birth up to below 1 year of age, the seroprevalence rate was 82%. At one year of age the positive rate decreased to 66% before gradually rising so that the percentage seropositivity of 6 to 10 years old becomes similar to that in older children and adults (11 to 40 years). The positive rate then starts to decline after 40 years of age. Using a standardized scoring system, the corresponding antibody titer was found to be high in the very young population and starts to decline after the age of 15 years. This suggests that in our population group, primary infection occurs mainly in the pediatric age group. It also accounts for the low positive rate in the age group of 61 years and above, as by then the titer had fallen to the level below the detection limits of the assay system.
  13. Chem YK, Chua KB, Malik Y, Voon K
    Trop Biomed, 2015 Jun;32(2):344-51.
    PMID: 26691263 MyJurnal
    Monoclonal antibody-escape variant of dengue virus type 1 (MabEV DEN-1) was discovered and isolated in an outbreak of dengue in Klang Valley, Malaysia from December 2004 to March 2005. This study was done to investigate whether DEN152 (an isolate of MabEV DEN-1) is a product of recombination event or not. In addition, the non-synonymous mutations that correlate with the monoclonal antibody-escape variant were determined in this study. The genomes of DEN152 and two new DEN-1 isolates, DENB04 and DENK154 were completely sequenced, aligned, and compared. Phylogenetic tree was plotted and the recombination event on DEN152 was investigated. DEN152 is sub-grouped under genotype I and is closely related genetically to a DEN-1 isolated in Japan in 2004. DEN152 is not a recombinant product of any parental strains. Four amino acid substitutions were unique only to DEN 152. These amino acid substitutions were (Ser)[326](Leu), (Ser)[340](Leu) at the deduced E protein, (Ile)[250](Thr) at NS1 protein, and (Thr)[41](Ser) at NS5 protein. Thus, DEN152 is an isolate of the emerging monoclonal antibody-escape variant DEN-1 that escaped diagnostic laboratory detection.
  14. Chua KH, Ooh YY, Chai HC
    Int. J. Immunogenet., 2016 Oct;43(5):303-9.
    PMID: 27519474 DOI: 10.1111/iji.12287
    Tumour necrosis factor superfamily 4 (TNFSF4) gene has been reported to be associated with systemic lupus erythematosus (SLE) susceptibility due to its encoding for OX40L protein that can increase autoantibody production and cause imbalance of T-cell proliferation. The purpose of this study was to investigate the association of TNFSF4 rs2205960, rs1234315, rs8446748 and rs704840 with SLE in the Malaysian population. A total of 476 patients with SLE and 509 healthy controls were recruited. Real-time polymerase chain reaction (PCR) was applied to genotype the selected single nucleotide polymorphisms (SNPs). Allelic and genotypic frequencies of each SNP were calculated for each ethnic group, and association test was performed using logistic regression. The overall association of each SNP in Malaysian patients with SLE was determined with meta-analysis. The frequency of minor T allele of TNFSF4 rs2205960 was significant in Chinese and Indian patients with SLE, with P values of 0.05 (OR = 1.27, 95% CI: 1.00-1.61) and 0.004 (OR = 3.16, 95% CI: 1.41-7.05), respectively. Significant association of minor G allele of rs704840 with SLE was also observed in Chinese (P = 0.03, OR = 1.26, 95% CI: 1.02-1.56). However, after Bonferroni correction, only T allele of rs2205960 remained significantly associated with Indian cohort. Overall, minor G allele of rs704840 showed significant association with SLE in the Malaysian population with P values of 0.05 (OR = 1.20, 95% CI: 1.00-1.43). We suggested TNFSF4 rs704840 could be the potential SLE risk factors in the Malaysian population.
  15. Tan XC, Chua KH, Ravishankar Ram M, Kuppusamy UR
    Food Chem, 2016 Apr 1;196:242-50.
    PMID: 26593489 DOI: 10.1016/j.foodchem.2015.09.042
    Various strategies have been adopted to combat complications caused by Type 2 diabetes mellitus and controlled diet is one of them. Monoterpenes, major constituents of essential oils, are synthesized and widely used as artificial food flavors. A series of twelve monoterpenes were assessed in the present study. Monoterpenes, exhibited low 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity even at high concentrations. Some monoterpenes inhibited α-amylase and α-glucosidase activity and stimulated glucose uptake and lipolysis. Monoterpenes such as (R)-(+)-limonene stimulated both glucose uptake (17.4%) and lipolysis (17.7%); the mRNA expression of glucose transporter 1 (GLUT1) was upregulated but glucose transporter 4 (GLUT4) was unaffected, and adipose triglyceride lipase (ATGL) was suppressed. Taken together, the selected monoterpenes may not confer strong protection against free radicals but nevertheless, their positive influence on lipid and glucose metabolism may have potential in the control of obesity and Type 2 diabetes mellitus.
  16. Safwani WK, Makpol S, Sathapan S, Chua K
    Arch Med Sci, 2014 Jun 29;10(3):597-606.
    PMID: 25097593 DOI: 10.5114/aoms.2014.43753
    Adipose tissue is a source of multipotent adult stem cells. Most studies on human adipose-derived stem cells (ASC) have been on the early passages. Studies in extensive expansion have not been well established yet. In this study, we aim to investigate the effects of extensive expansion on the adipogenic differentiation capability of ASC.
  17. Malon RS, Chua KY, Wicaksono DH, Córcoles EP
    Analyst, 2014 Jun 21;139(12):3009-16.
    PMID: 24776756 DOI: 10.1039/c4an00201f
    Lactate measurement is vital in clinical diagnostics especially among trauma and sepsis patients. In recent years, it has been shown that saliva samples are an excellent applicable alternative for non-invasive measurement of lactate. In this study, we describe a method for the determination of lactate concentration in saliva samples by using a simple and low-cost cotton fabric-based electrochemical device (FED). The device was fabricated using template method for patterning the electrodes and wax-patterning technique for creating the sample placement/reaction zone. Lactate oxidase (LOx) enzyme was immobilised at the reaction zone using a simple entrapment method. The LOx enzymatic reaction product, hydrogen peroxide (H2O2) was measured using chronoamperometric measurements at the optimal detection potential (-0.2 V vs. Ag/AgCl), in which the device exhibited a linear working range between 0.1 to 5 mM, sensitivity (slope) of 0.3169 μA mM(-1) and detection limit of 0.3 mM. The low detection limit and wide linear range were suitable to measure salivary lactate (SL) concentration, thus saliva samples obtained under fasting conditions and after meals were evaluated using the FED. The measured SL varied among subjects and increased after meals randomly. The proposed device provides a suitable analytical alternative for rapid and non-invasive determination of lactate in saliva samples. The device can also be adapted to a variety of other assays that requires simplicity, low-cost, portability and flexibility.
  18. Lee PC, Lam HH, Ghani SA, Subrayan V, Chua KH
    Genet. Mol. Res., 2014;13(2):3553-9.
    PMID: 24737507 DOI: 10.4238/2014.March.24.15
    Mutations in the PAX6 gene that cause aniridia have been identified in various ethnicities but not in the Malaysian population. Therefore, the objective of this study was to investigate the PAX6 mutation in a Malaysian family with congenital aniridia. In this study, a complete ophthalmic examination was performed on a Dusun ethnic family with aniridia. Genomic DNA was extracted from the peripheral blood of the subjects and screened for the PAX6 gene mutation using polymerase chain reaction amplification high-resolution melting curve analysis (PCR-HRM) followed by confirmation via direct DNA sequencing. A heterozygous G deletion (c.857delG) in exon 7 causing a frame shift in PAX6 was identified in all affected family members. Genotype-phenotype correlation analysis revealed congenital cataract and all affected family members showed a similar spectrum of aniridia with no phenotypic variability but with differences in severity that were age-dependent. In summary, by using a PCR-HRM approach, this study is the first to report a PAX6 mutation in a Malaysian family. This mutation is the cause of the aniridia spectra observed in this family and of congenital cataract.
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