Displaying publications 1 - 20 of 47 in total

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  1. Viability of dengue virus in culture stocks is efficiently preserved by storage in diluted forms
    Suppiah J, Nadaraju S, Hamzah S, Chee HY
    Trop Biomed, 2020 Jun 01;37(2):282-287.
    PMID: 33612798
    Storage of dengue virus (DENV) culture stocks in -80°C is a common laboratory practice to maintain the viability of the virus for long-term usage. However, the efficiency of this method could still be hindered by multiple factors. In our laboratory, we observed a constant and substantial deterioration in the titer of DENV in Vero culture supernatant stored in -80°C. Such incident had badly hampered the laboratory work and prompted an investigation to determine the cause. DENV isolates representing all four serotypes were propagated and the culture supernatants were harvested and stored in aliquots of original stock and 10 fold dilutions (10-1 -10-4). DENV titer in these stocks was determined prior to storage and reassessed on the third and sixth month of storage by focus forming unit assay (FFUA). The result demonstrated a constant preservation of titer ranging from 104 ffu/ml to 105 ffu/ml in the diluted DENV virus culture stocks of 10-1, and 10-2 of DENV1-4, a minor reduction of titer from 103 ffu/ml to 102 ffu/ml at dilution 10-3 for DENV4 only and complete deterioration in undiluted culture stock and lower dilution (10-4) within 6 months of storage in -80°C for all serotypes. It is recommended that propagated DENV in Vero cells are stored in 10 fold dilutions as compared to the original form to preserve the titer for long-term usage.
  2. Ultrastructural changes of cell morphology and viral morphogenesis of two ecotypes of dengue virus infection in human monocytic U-937 cell
    Fish-Low CY, Abu Bakar S, Othman F, Chee HY
    Trop Biomed, 2018 Dec 01;35(4):1154-1159.
    PMID: 33601863
    Dengue virus (DENV) is maintained and circulated in both sylvatic/enzootic and endemic/human cycles and spill over infection of sylvatic DENV into human populations has been reported. Extensive deforestation and increase human activities in forest may increase the risk of human exposure to sylvatic dengue infection and this may become a threat to human. Present study investigated the changes in cell morphology and viral morphogenesis upon infection with sylvatic and endemic ecotypes in human monocytic U-937 cells using transmission electron microscopy. Autophagy, a process that is either pro-viral or anti-viral, was observed in U-937 cells of both infections, however only the replication of endemic DENV was evidenced. An insight into the infection responses of sylvatic progenitors of DENV in susceptible host cells may provide better understanding on dengue emergence in human populations.
  3. Ultrastructural aspects of sylvatic dengue virus infection in Vero cell
    Fish-Low CY, Abubakar S, Othman F, Chee HY
    Malays J Pathol, 2019 Apr;41(1):41-46.
    PMID: 31025636
    INTRODUCTION: Dengue virus (DENV), the causative agent of dengue disease exists in sylvatic and endemic ecotypes. The cell morphological changes and viral morphogenesis of two dengue ecotypes were examined at the ultrastructural level to identify potential similarities and differences in the surrogate model of enzootic host.

    MATERIALS AND METHODS: Vero cells were inoculated with virus at a multiplicity of infection (MOI) of 0.1. Cell cultures were harvested over a time course and processed for transmission electron microscopic imaging.

    RESULTS: The filopodia protrusions on cell periphery preceded virus entry. Additionally, sylvatic DENV infection was found spreading slower than the endemic DENV. Morphogenesis of both dengue ecotypes was alike but at different level of efficiency in the permissive cells.

    CONCLUSIONS: This is the first ultrastructural study on sylvatic DENV and this comparative study revealed the similarities and differences of cellular responses and morphogenesis of two dengue ecotypes in vitro. The study revealed the weaker infectivity of sylvatic DENV in the surrogate model of enzootic host, which supposed to support better replication of enzootic DENV than endemic DENV.

  4. Fulltext The predictive and diagnostic accuracy of vascular endothelial growth factor and pentraxin-3 in severe dengue
    Low GKK, Gan SC, Zainal N, Naidu KD, Amin-Nordin S, Khoo CS, et al.
    Pathog Glob Health, 2018 09;112(6):334-341.
    PMID: 30246621 DOI: 10.1080/20477724.2018.1516417
    This study aimed to evaluate vascular endothelial growth factor (VEGF) and pentraxin 3 (PTX-3) as predictive and diagnostic markers in differentiating severe dengue from non-severe dengue. The study was conducted in Ampang Health Clinic, Ampang Hospital and Serdang Hospital. The plasma levels of VEGF and PTX-3 were compared between severe dengue and non-severe dengue by ELISA from the day of presentation until discharged. Multiple logistic regression was used to develop predictive and diagnostic models by incorporating other clinical parameters. The receiver operating characteristics (ROC) analysis was used to assess the accuracy of the biomarkers and the developed models. Eighty-two patients were recruited, 29 with severe dengue and four died. The Area Under the Curve (AUC) was statistically significant in VEGF as diagnostic marker at Day 2 and 3 of illness with sensitivity of 80.00%-100.00% and specificity of 76.47%-80.00%. The predictive model with AUC of 0.84 (p 
  5. Fulltext Systematic review and meta-analysis of the efficacy and safety of oseltamivir (Tamiflu) in the treatment of Coronavirus Disease 2019 (COVID-19)
    Aliyu B, Raji YE, Chee HY, Wong MY, Sekawi ZB
    PLoS One, 2022;17(12):e0277206.
    PMID: 36454880 DOI: 10.1371/journal.pone.0277206
    Efforts are ongoing by researchers globally to develop new drugs or repurpose existing ones for treating COVID-19. Thus, this led to the use of oseltamivir, an antiviral drug used for treating influenza A and B viruses, as a trial drug for COVID-19. However, available evidence from clinical studies has shown conflicting results on the effectiveness of oseltamivir in COVID-19 treatment. Therefore, this systematic review and meta-analysis was performed to assess the clinical safety and efficacy of oseltamivir for treating COVID-19. The study was conducted according to the PRISMA guidelines, and the priori protocol was registered in PROSPERO (CRD42021270821). Five databases were searched, the identified records were screened, and followed by the extraction of relevant data. Eight observational studies from four Asian countries were included. A random-effects model was used to pool odds ratios (ORs), mean differences (MD), and their 95% confidence intervals (CI) for the study analysis. Survival was not significantly different between all categories of oseltamivir and the comparison groups analysed. The duration of hospitalisation was significantly shorter in the oseltamivir group following sensitivity analysis (MD -5.95, 95% CI -9.91--1.99 p = 0.003, heterogeneity I2 0%, p = 0.37). The virological, laboratory and radiological response rates were all not in favour of oseltamivir. However, the electrocardiographic safety parameters were found to be better in the oseltamivir group. However, more studies are needed to establish robust evidence on the effectiveness or otherwise of oseltamivir usage for treating COVID-19.
  6. Fulltext Synthesis, characterization and evaluation of antidengue activity of enantiomeric Schiff bases derived from S-substituted dithiocarbazate
    Maryam M, Tan SL, Crouse KA, Mohamed Tahir MI, Chee HY
    Turk J Chem, 2020;44(5):1395-1409.
    PMID: 33488239 DOI: 10.3906/kim-2006-22
    A series of Schiff bases have been successfully synthesized through the acid-catalyzed condensation of S-substituted dithiocarbazates and three enantiomerically pure monoterpenes, (1 R )-(+)-camphor, (1 S )-(-)-camphor, (1 R )-(-)-camphorquinone, (1 S )-(+)-camphorquinone, ( R )-(-)-carvone and ( S )-(+)-carvone. Spectroscopic results revealed that the Schiff bases containing camphor or carvone likely adopted an E -configuration along the characteristic imine bond while those containing camphorquinone assumed a Z -configuration. The antidengue potential of these compounds was evaluated based on DENV 2 caused cytopathic effect (CPE) reduction-based in vitro evaluation. The compounds were validated through secondary foci forming unit reduction assay (FFURA). Compounds were also tested for their cytotoxicity against Vero cells. The compounds showed variable degrees of antiviral activity with the camphor compounds displaying the highest antidengue potential. The enantiomers of the compounds behaved almost similarly during the antiviral evaluation.
  7. Fulltext Stem Cell Therapy in Dengue Virus-Infected BALB/C Mice Improves Hepatic Injury
    Sakinah S, Priya SP, Mok PL, Munisvaradass R, Teh SW, Sun Z, et al.
    Front Cell Dev Biol, 2021;9:637270.
    PMID: 34291043 DOI: 10.3389/fcell.2021.637270
    Extensive clinical efforts have been made to control the severity of dengue diseases; however, the dengue morbidity and mortality have not declined. Dengue virus (DENV) can infect and cause systemic damage in many organs, resulting in organ failure. Here, we present a novel report showing a tailored stem-cell-based therapy that can aid in viral clearance and rescue liver cells from further damage during dengue infection. We administered a combination of hematopoietic stem cells and endothelial progenitor cells in a DENV-infected BALB/c mouse model and found that delivery of this cell cocktail had improved their liver functions, confirmed by hematology, histopathology, and next-generation sequencing. These stem and progenitor cells can differentiate into target cells and repair the damaged tissues. In addition, the regime can regulate endothelial proliferation and permeability, modulate inflammatory reactions, enhance extracellular matrix production and angiogenesis, and secrete an array of growth factors to create an enhanced milieu for cell reparation. No previous study has been published on the treatment of dengue infection using stem cells combination. In conclusion, dengue-induced liver damage was rescued by administration of stem cell therapy, with less apoptosis and improved repair and regeneration in the dengue mouse model.
  8. Sensitive Leptospira DNA detection using tapered optical fiber sensor
    Zainuddin NH, Chee HY, Ahmad MZ, Mahdi MA, Abu Bakar MH, Yaacob MH
    J Biophotonics, 2018 08;11(8):e201700363.
    PMID: 29570957 DOI: 10.1002/jbio.201700363
    This paper presents the development of tapered optical fiber sensor to detect a specific Leptospira bacteria DNA. The bacteria causes Leptospirosis, a deadly disease but with common early flu-like symptoms. Optical single mode fiber (SMF) of 125 μm diameter is tapered to produce 12 μm waist diameter and 15 cm length. The novel DNA-based optical fiber sensor is functionalized by incubating the tapered region with sodium hydroxide (NaOH), (3-Aminopropyl) triethoxysilane and glutaraldehyde. Probe DNA is immobilized onto the tapered region and subsequently hybridized by its complementary DNA (cDNA). The transmission spectra of the DNA-based optical fiber sensor are measured in the 1500 to 1600 nm wavelength range. It is discovered that the shift of the wavelength in the SMF sensor is linearly proportional with the increase in the cDNA concentrations from 0.1 to 1.0 nM. The sensitivity of the sensor toward DNA is measured to be 1.2862 nm/nM and able to detect as low as 0.1 fM. The sensor indicates high specificity when only minimal shift is detected for non-cDNA testing. The developed sensor is able to distinguish between actual DNA of Leptospira serovars (Canicola and Copenhageni) against Clostridium difficile (control sample) at very low (femtomolar) target concentrations.
  9. Fulltext Room-temperature stable loop-mediated isothermal amplification (LAMP) reagents to detect leptospiral DNA
    Lee PY, Wong YP, Othman S, Chee HY
    Asian Biomed (Res Rev News), 2021 Aug;15(4):183-189.
    PMID: 37551329 DOI: 10.2478/abm-2021-0023
    BACKGROUND: Loop-mediated isothermal amplification (LAMP) is one of the most promising tools for rapidly detecting Leptospira spp. However, LAMP is hampered by cold storage to maintain the enzymatic activity of Bst DNA polymerase.

    OBJECTIVE: To overcome the drawback of cold storage requirement for LAMP reagents we modified the reagents by adding sucrose as stabilizer. We then sought to determine the stability at room temperature of the premixed LAMP reagents containing sucrose.

    METHOD: Premixed LAMP reagents with sucrose and without sucrose were prepared. The prepared mixtures were stored at room temperature for up to 60 days, and were subjected to LAMP reactions at various intervals using rat kidney samples to detect leptospiral DNA.

    RESULTS: The premixed LAMP reagents with sucrose remained stable for 45 days while sucrose-free premixed LAMP reagents showed no amplification from day 1 of storage at room temperature up to day 14.

    CONCLUSION: The LAMP reagent system can be refined by using sucrose as stabilizer, thus allowing their storage at room temperature without the need for cold storage. The modified method enables greater feasibility of LAMP for field surveillance and epidemiology in resource-limited settings.

  10. Putative apolipoprotein A-I, natural killer cell enhancement factor and lysozyme g are involved in the early immune response of brown-marbled grouper, Epinephelus fuscoguttatus, Forskal, to Vibrio alginolyticus
    Low CF, Shamsudin MN, Chee HY, Aliyu-Paiko M, Idrus ES
    J Fish Dis, 2014 Aug;37(8):693-701.
    PMID: 24304156 DOI: 10.1111/jfd.12153
    The gram-negative bacterium, Vibrio alginolyticus, has frequently been identified as the pathogen responsible for the infectious disease called vibriosis. This disease is one of the major challenges facing brown-marbled grouper aquaculture, causing fish farmers globally to suffer substantial economic losses. The objective of this study was to investigate the proteins involved in the immune response of brown-marbled grouper fingerlings during their initial encounter with pathogenic organisms. To achieve this objective, a challenge experiment was performed, in which healthy brown-marbled grouper fingerlings were divided into two groups. Fish in the treated group were subjected to intraperitoneal injection with an infectious dose of V. alginolyticus suspended in phosphate-buffered saline (PBS), and those in the control group were injected with an equal volume of PBS. Blood samples were collected from a replicate number of fish from both groups at 4 h post-challenge and analysed for immune response-related serum proteins via two-dimensional gel electrophoresis. The results showed that 14 protein spots were altered between the treated and control groups; these protein spots were further analysed to determine the identity of each protein via MALDI-TOF/TOF. Among the altered proteins, three were clearly overexpressed in the treated group compared with the control; these were identified as putative apolipoprotein A-I, natural killer cell enhancement factor and lysozyme g. Based on these results, these three highly expressed proteins participate in immune response-related reactions during the initial exposure (4 h) of brown-marbled grouper fingerling to V. alginolyticus infection.
  11. Outbreak of fatal childhood viral infection in Sarawak, Malaysia in 1997: inocula of patients' clinical specimens induce apoptosis in vitro
    Abubakar S, Shafee N, Chee HY
    Malays J Pathol, 1998 Dec;20(2):71-81.
    PMID: 10879266
    Identification of the aetiologic agent(s) associated with an outbreak of fatal childhood viral infection in Sarawak, Malaysia, in mid 1997 remains elusive. It is reported here that African green monkey kidney (Vero) and human monocytic (U937) cells treated with inocula derived from clinical specimens of some of these fatal cases showed the presence of cellular genomic DNA degradation when the extracted DNA was separated by pulsed field gel electrophoresis (PFGE), oligonucleosomal DNA ladders characteristic of apoptotic cells when the infected cells' DNA was separated by agarose gel electrophoresis, and apoptotic cellular DNA fragmentation when cells were stained using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL). These results suggest that inocula derived from the patients' clinical specimens contain factors which stimulate apoptotic cellular responses in vitro.
  12. Non-immune-related genes and signalling pathways in spleen of Vibrio parahaemolyticus-infected Epinephelus fuscoguttatus (Forskal)
    Low CF, Mariana NS, Maha A, Chee HY, Fatimah MY
    J Fish Dis, 2015 Aug;38(8):761-4.
    PMID: 25073481 DOI: 10.1111/jfd.12283
  13. Molecular detection of enteroviruses from an outbreak of hand, foot and mouth disease in Malaysia in 1997
    Abubakar S, Chee HY, Shafee N, Chua KB, Lam SK
    Scand. J. Infect. Dis., 1999;31(4):331-5.
    PMID: 10528868
    Enterovirus 5'UTR sequences were detected by RT-PCR in 22 out of 47 suspected hand, foot and mouth disease (HFMD) patients during an outbreak of the disease with incidences of fatal brainstem encephalomyelitis in Malaysia in 1997. Genetic and phylogenetic analyses of the isolates 5'UTR sequences suggest the presence of predominantly enteroviruses with high sequence similarities to Echovirus 1 and Coxsackievirus A9 in the Malaysian peninsula. No fatal cases, however, were associated with these isolates. The remaining isolates, including all (4/4) isolates of the fatal cases from the Malaysian peninsula and Sarawak shared very high sequence identity with enterovirus 71MS (EV71). These findings suggest that several enteroviruses were circulating in Malaysia during the outbreak period, with only EV71 causing fatal infections.
  14. Micro-anatomical changes in major blood vessel caused by dengue virus (serotype 2) infection
    Priya SP, Sakinah S, Ling MP, Chee HY, Higuchi A, Hamat RA, et al.
    Acta Trop, 2017 Jul;171:213-219.
    PMID: 28427958 DOI: 10.1016/j.actatropica.2017.04.010
    Dengue virus (DENV) has emerged as a major economic concern in developing countries, with 2.5 billion people believed to be at risk. Vascular endothelial cells (ECs) lining the circulatory system from heart to end vessels perform crucial functions in the human body, by aiding gas exchange in lungs, gaseous, nutritional and its waste exchange in all tissues, including the blood brain barrier, filtration of fluid in the glomeruli, neutrophil recruitment, hormone trafficking, as well as maintenance of blood vessel tone and hemostasis. These functions can be deregulated during DENV infection. In this study, BALB/c mice infected with DENV serotype 2 were analyzed histologically for changes in major blood vessels in response to DENV infection. In the uninfected mouse model, blood vessels showed normal architecture with intact endothelial monolayer, tunica media, and tunica adventitia. In the infected mouse model, DENV distorted the endothelium lining and disturbed the smooth muscle, elastic laminae and their supporting tissues causing vascular structural disarrangement. This may explain the severe pathological illness in DENV-infected individuals. The overall DENV-induced damages on the endothelial and it's supporting tissues and the dysregulated immune reactions initiated by the host were discussed.
  15. Fulltext Meta-analysis of biomarkers for severe dengue infections
    Soo KM, Khalid B, Ching SM, Tham CL, Basir R, Chee HY
    PeerJ, 2017;5:e3589.
    PMID: 28929009 DOI: 10.7717/peerj.3589
    BACKGROUND: Dengue viral infection is an acute infection that has the potential to have severe complications as its major sequela. Currently, there is no routine laboratory biomarker with which to predict the severity of dengue infection or monitor the effectiveness of standard management. Hence, this meta-analysis compared biomarker levels between dengue fever (DF) and severe dengue infections (SDI) to identify potential biomarkers for SDI.

    METHODS: Data concerning levels of cytokines, chemokines, and other potential biomarkers of DF, dengue hemorrhagic fever, dengue shock syndrome, and severe dengue were obtained for patients of all ages and populations using the Scopus, PubMed, and Ovid search engines. The keywords "(IL1* or IL-1*) AND (dengue*)" were used and the same process was repeated for other potential biomarkers, according to Medical Subject Headings terms suggested by PubMed and Ovid. Meta-analysis of the mean difference in plasma or serum level of biomarkers between DF and SDI patients was performed, separated by different periods of time (days) since fever onset. Subgroup analyses comparing biomarker levels of healthy plasma and sera controls, biomarker levels of primary and secondary infection samples were also performed, as well as analyses of different levels of severity and biomarker levels upon infection by different dengue serotypes.

    RESULTS: Fifty-six studies of 53 biomarkers from 3,739 dengue cases (2,021 DF and 1,728 SDI) were included in this meta-analysis. Results showed that RANTES, IL-7, IL-8, IL-10, IL-18, TGF-b, and VEGFR2 levels were significantly different between DF and SDI. IL-8, IL-10, and IL-18 levels increased during SDI (95% CI, 18.1-253.2 pg/mL, 3-13 studies, n = 177-1,909, I(2) = 98.86%-99.75%). In contrast, RANTES, IL-7, TGF-b, and VEGFR2 showed a decrease in levels during SDI (95% CI, -3238.7 to -3.2 pg/mL, 1-3 studies, n = 95-418, I(2) = 97.59%-99.99%). Levels of these biomarkers were also found to correlate with the severity of the dengue infection, in comparison to healthy controls. Furthermore, the results showed that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 display peak differences between DF and SDI during or before the critical phase (day 4-5) of SDI.

    DISCUSSION: This meta-analysis suggests that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 may be used as potential early laboratory biomarkers in the diagnosis of SDI. This can be used to predict the severity of dengue infection and to monitor the effectiveness of treatment. Nevertheless, methodological and reporting limitations must be overcome in future research to minimize variables that affect the results and to confirm the findings.
  16. Fulltext Meta-Analysis of Dengue Severity during Infection by Different Dengue Virus Serotypes in Primary and Secondary Infections
    Soo KM, Khalid B, Ching SM, Chee HY
    PLoS One, 2016;11(5):e0154760.
    PMID: 27213782 DOI: 10.1371/journal.pone.0154760
    INTRODUCTION: Dengue virus (DENV) infection is currently a major cause of morbidity and mortality in the world; it has become more common and virulent over the past half-century and has gained much attention. Thus, this review compared the percentage of severe cases of both primary and secondary infections with different serotypes of dengue virus.

    METHODS: Data related to the number of cases involving dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS) or severe dengue infections caused by different serotypes of dengue virus were obtained by using the SCOPUS, the PUBMED and the OVID search engines with the keywords "(dengue* OR dengue virus*) AND (severe dengue* OR severity of illness index* OR severity* OR DF* OR DHF* OR DSS*) AND (serotypes* OR serogroup*)", according to the MESH terms suggested by PUBMED and OVID.

    RESULTS: Approximately 31 studies encompassing 15,741 cases reporting on the dengue serotypes together with their severity were obtained, and meta-analysis was carried out to analyze the data. This study found that DENV-3 from the Southeast Asia (SEA) region displayed the greatest percentage of severe cases in primary infection (95% confidence interval (CI), 31.22-53.67, 9 studies, n = 598, I2 = 71.53%), whereas DENV-2, DENV-3, and DENV-4 from the SEA region, as well as DENV-2 and DENV-3 from non-SEA regions, exhibited the greatest percentage of severe cases in secondary infection (95% CI, 11.64-80.89, 4-14 studies, n = 668-3,149, I2 = 14.77-96.20%). Moreover, DENV-2 and DENV-4 from the SEA region had been found to be more highly associated with dengue shock syndrome (DSS) (95% CI, 10.47-40.24, 5-8 studies, n = 642-2,530, I2 = 76.93-97.70%), while DENV-3 and DENV-4 from the SEA region were found to be more highly associated with dengue hemorrhagic fever (DHF) (95% CI, 31.86-54.58, 9 studies, n = 674-2,278, I2 = 55.74-88.47%), according to the 1997 WHO dengue classification. Finally, DENV-2 and DENV-4 from the SEA region were discovered to be more highly associated with secondary infection compared to other serotypes (95% CI, 72.01-96.32, 9-12 studies, n = 671-2,863, I2 = 25.01-96.75%).

    CONCLUSION: This study provides evidence that the presence of certain serotypes, including primary infection with DENV-3 from the SEA region and secondary infection with DENV-2, DENV-3, and DENV-4 also from the SEA region, as well as DENV-2 and DENV-3 from non SEA regions, increased the risk of severe dengue infections. Thus, these serotypes are worthy of special consideration when making clinical predictions upon the severity of the infection.

    SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42015026093 (http://www.crd.york.ac.uk/PROSPERO).

  17. Fulltext Mast cell stabilizing effect of a geranyl acetophenone in dengue virus infection using in vitro model of DENV3-induced RBL-2H3 cells
    Tan JW, Wan Zahidi NF, Kow ASF, Soo KM, Shaari K, Israf DA, et al.
    Biosci Rep, 2019 06 28;39(6).
    PMID: 31110077 DOI: 10.1042/BSR20181273
    Mast cells (MCs), a type of immune effector cell, have recently become recognized for their ability to cause vascular leakage during dengue virus (DENV) infection. Although MC stabilizers have been reported to attenuate DENV induced infection in animal studies, there are limited in vitro studies on the use of MC stabilizers against DENV induced MC degranulation. 2,4,6-trihydroxy-3-geranyl acetophenone (tHGA) has been reported to be a potential MC stabilizer by inhibiting IgE-mediated MC activation in both cellular and animal models. The present study aims to establish an in vitro model of DENV3-induced RBL-2H3 cells using ketotifen fumarate as a control drug, as well as to determine the effect of tHGA on the release of MC mediators upon DENV infection. Our results demonstrated that the optimal multiplicities of infection (MOI) were 0.4 × 10-2 and 0.8 × 10-2 focus forming units (FFU)/cell. Ketotifen fumarate was proven to attenuate DENV3-induced RBL-2H3 cells degranulation in this in vitro model. In contrast, tHGA was unable to attenuate the release of both β-hexosaminidase and tumor necrosis factor (TNF)-α. Nonetheless, our study has successfully established an in vitro model of DENV3-induced RBL-2H3 cells, which might be useful for the screening of potential MC stabilizers for anti-dengue therapies.
  18. Fulltext Loop-mediated isothermal amplification (LAMP): a versatile technique for detection of micro-organisms
    Wong YP, Othman S, Lau YL, Radu S, Chee HY
    J Appl Microbiol, 2018 Mar;124(3):626-643.
    PMID: 29165905 DOI: 10.1111/jam.13647
    Loop-mediated isothermal amplification (LAMP) amplifies DNA with high specificity, efficiency and rapidity under isothermal conditions by using a DNA polymerase with high displacement strand activity and a set of specifically designed primers to amplify targeted DNA strands. Following its first discovery by Notomi et al. ( Nucleic Acids Res 28: E63), LAMP was further developed over the years which involved the combination of this technique with other molecular approaches, such as reverse transcription and multiplex amplification for the detection of infectious diseases caused by micro-organisms in humans, livestock and plants. In this review, available types of LAMP techniques will be discussed together with their applications in detection of various micro-organisms. Up to date, there are varieties of LAMP detection methods available including colorimetric and fluorescent detection, real-time monitoring using turbidity metre and detection using lateral flow device which will also be highlighted in this review. Apart from that, commercialization of LAMP technique had also been reported such as lyophilized form of LAMP reagents kit and LAMP primer sets for detection of pathogenic micro-organisms. On top of that, advantages and limitations of this molecular detection method are also described together with its future potential as a diagnostic method for infectious disease.
  19. Fulltext Interaction between Flavivirus and Cytoskeleton during Virus Replication
    Foo KY, Chee HY
    Biomed Res Int, 2015;2015:427814.
    PMID: 26347881 DOI: 10.1155/2015/427814
    Flaviviruses are potentially human pathogens that cause major epidemics worldwide. Flavivirus interacts with host cell factors to form a favourable virus replication site. Cell cytoskeletons have been observed to have close contact with flaviviruses, which expands the understanding of cytoskeleton functions during virus replication, although many detailed mechanisms are still unclear. The interactions between the virus and host cytoskeletons such as actin filaments, microtubules, and intermediate filaments have provided insight into molecular alterations during the virus infection, such as viral entry, in-cell transport, scaffold assembly, and egress. This review article focuses on the utilization of cytoskeleton by Flavivirus and the respective functions during virus replication.
  20. Fulltext Induction of apoptosis in neurogenic pulmonary edema
    Abu Bakar S, Shafee N, Chee HY
    Med J Malaysia, 1999 Sep;54(3):402-3.
    PMID: 11045072
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