Displaying publications 21 - 40 of 97 in total

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  1. Choo KE, Tan KK, Chuah SP, Ariffin WA, Gururaj A
    Ann Trop Paediatr, 1994;14(3):231-7.
    PMID: 7825997
    This is a retrospective study of the epidemiology, clinical features, laboratory findings, treatment and outcome of haemorrhagic disease in 42 Kelantanese infants who were admitted to Hospital Universiti Sains Malaysia during a 2-year period (1987-1988). Classical haemorrhagic disease of the newborn was the commonest presentation (48%), followed by early onset (29%) and late onset (24%) disease. Home deliveries accounted for 81% of the affected infants. Most of these babies were not given vitamin K at birth in contrast to those delivered in hospitals. All except one infant were breastfed. The six commonest presenting clinical features were pallor, jaundice, umbilical cord bleeding, tense fontanelle, convulsions and hepatomegaly. All the infants had prolonged prothrombin and partial thromboplastin times which were corrected by administration of vitamin K. Subdural haemorrhage was the commonest form of intracranial haemorrhage, followed by subarachnoid haemorrhage. The overall case fatality rate was 14%. The results of this study once again emphasize the value of vitamin K prophylaxis in the newborn.
  2. Mohd A, Zainal N, Tan KK, AbuBakar S
    Sci Rep, 2019 10 04;9(1):14336.
    PMID: 31586088 DOI: 10.1038/s41598-019-50674-3
    Zika virus (ZIKV) infection is a serious public health concern. ZIKV infection has been associated with increased occurrences of microcephaly among newborns and incidences of Guillain-Barré syndrome among adults. No specific therapeutics or vaccines are currently available to treat and protect against ZIKV infection. Here, a plant-secreted phytoalexin, resveratrol (RES), was investigated for its ability to inhibit ZIKV replication in vitro. Several RES treatment regimens were used. The ZIKV titers of mock- and RES-treated infected cell cultures were determined using the focus-forming assay and the Zika mRNA copy number as determined using qRT-PCR. Our results suggested that RES treatment reduced ZIKV titers in a dose-dependent manner. A reduction of >90% of virus titer and ZIKV mRNA copy number was achieved when infected cells were treated with 80 µM of RES post-infection. Pre-incubation of the virus with 80 µM RES showed >30% reduction in ZIKV titers and ZIKV mRNA copy number, implying potential direct virucidal effects of RES against the virus. The RES treatment reduced >70% virus titer in the anti-adsorption assay, suggesting the possibility that RES also interferes with ZIKV binding. However, there was no significant decrease in ZIKV titer when a short-period of RES treatment was applied to cells before ZIKV infection (pre-infection) and after the virus bound to the cells (virus internalization inhibition), implying that RES acts through its continuous presence in the cell cultures after virus infection. Overall, our results suggested that RES exhibited direct virucidal activity against ZIKV and possessed anti-ZIKV replication properties, highlighting the need for further exploration of RES as a potential antiviral molecule against ZIKV infection.
  3. Loong SK, Tan KK, Zulkifle NI, AbuBakar S
    Data Brief, 2019 Aug;25:104159.
    PMID: 31312701 DOI: 10.1016/j.dib.2019.104159
    Paraburkholderia fungorum is an opportunistic bacteria infrequently associated with human infections. Here, we report the draft genome sequence of P. fungorum strain BF370, recovered from the synovial tissue of a patient in Malaysia. The P. fungorum genome contains a 8,950,957 bp chromosome with a G+C content of 61.8%. Colicin and heavy metal resistant genes were also present in the genome. Conserved sequence indels unique to P. fungorum were observed in the genome. The draft genome was deposited at the European Nucleotide Archive under the sample accession number ERS1776561 and study accession number PRJEB17921.
  4. Loong SK, Tan KK, Sulaiman S, Wong PF, AbuBakar S
    Genom Data, 2017 Jun;12:69-70.
    PMID: 28377885 DOI: 10.1016/j.gdata.2017.03.004
    In this study, we present the draft genome sequence of B. pseudohinzii BH370 recovered from the trachea and lung tissues of an ICR mouse in Malaysia. The genome consists of 4,474,040 bp with a GC content of 66.4%. Annotation using RAST algorithm displayed 5119 protein encoding and 52 RNA genes. The CRISPR-cas genomic sequences previously reported in B. pseudohinzii were identified. The nucleotide sequences of BH370 was deposited into the European Nucleotide Archive under the genome assembly accession number FPJN01000000.
  5. Lim KY, Ang EL, Tan KK, Mustakim S
    MyJurnal
    Neonatal malaria may be overlooked likely due to its non-specific features and low prevalence in Malaysia. In this case report, we detail a case of neonatal malaria in an 18-day old baby girl of Myanmar origin who presented with 6 days of intermittent fever but was otherwise well. Initially, she was treated as neonatal sepsis. She then developed thrombocytopaenia and severe anaemia with persistent spikes of temperature. This prompted a series of investigations and multiple changes of antibiotics. The diagnosis of neonatal malaria surfaced when her peripheral blood film incidentally revealed the presence of Plasmodium vivax parasites. Peripheral blood smears are simple and inexpensive. Therefore practising especially in endemic areas for malaria, we need to consider this diagnosis when dealing with neonatal sepsis that does not respond to standard treatment.
  6. Khoo HY, Lee HY, Khor CS, Tan KK, AbuBakar S
    Trop Biomed, 2021 Dec 01;38(4):613-621.
    PMID: 35001928 DOI: 10.47665/tb.38.4.105
    The recommended test guidelines for Zika virus (ZIKV) include using both molecular and serological tools. While the molecular tools are useful for detecting acute infection, the serological tools are useful for the detection of previous infections. Nevertheless, detection of ZIKV-specific antibodies remains a challenge due to the high cross-reactivity between ZIKV and other flaviviruses such as dengue virus (DENV) and Japanese encephalitis virus (JEV). The objective of this study is to evaluate the commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of ZIKV IgG. In this study, we evaluated 6 commercially available anti-ZIKV IgG ELISA kits. Pre-characterized serum panels consisting of 70 sera were selected for the evaluation. The diagnostic accuracy of each ELISA kits was determined and compared to the gold standard, Foci Reduction Neutralization Test (FRNT). The present study established that the performance of the NS1-based anti-ZIKV IgG ELISA kit was superior to that which uses of the E protein as antigen. Overall, commercial ZIKV IgG ELISA showed varying test performances, with some achieving moderate to high test sensitivities and specificities. When compared against the FRNT, the test sensitivities ranged from 7.1% to 78.6%, whereas, the test specificities ranged from 40.0% to 100%. Limitation to the study includes the cross reactivity between flavivirus and specificity of the kit in addressing the cross reactivity.
  7. Goh KL, Parasakthi N, Peh SC, Anderson PE, Tan KK
    Singapore Med J, 1995 Dec;36(6):619-20.
    PMID: 8781634
    Omeprazole has been shown to have a suppressive effect on Helicobacter pylori. The aim of this study was to determine if prolonged treatment with omeprazole would result in a higher eradication rate than short course treatment. Twenty patients with endoscopy proven duodenal ulcers and unequivocal evidence of Helicobacter pylori (HP) infection based on culture, histology, urease test and Gram's stain of a fresh tissue smear were treated with omeprazole 40 mg om for 2-4 weeks. Following ulcer healing, patients received either maintenance omeprazole 20 mg om or placebo for up to one year. All 20 patients had healed ulcers following a 2-4 week course of omeprazole 40 mg om.. All were negative for HP at the end of treatment. Thirteen patients received short course therapy with omeprazole only, followed by placebo. On follow-up endoscopy at 3 months, only one of 13 (7.7%) had eradicated the bacteria. Seven patients received maintenance treatment with omeprazole 20mg om for one year. Following completion of treatment, patients were followed up at 1, 3 and 6 months. Only one of 7 (14.3%) patients had eradicated the infection on long term follow-up. The eradication rates of HP with both short and long course omeprazole monotherapy were low.
  8. Tan KK, Sin KS, Ng AJ, Yahya H, Kaur P
    Singapore Med J, 1994 Dec;35(6):648-9.
    PMID: 7761898
    Non-O1 vibrio cholerae infections are associated with sporadic cases of gastroenteritis and extraintestinal infections. Septicaemia due to non-O1 vibrio cholerae is rare and are mainly reported in adults, particularly in immunocompromised patients. We report a case of non-O1 vibrio cholerae septicaemia and gastroenteritis in an 8-year-old child. The patient presented with bloody diarrhoea, fever and severe dehydration. Non-O1 vibrio cholerae were isolated from blood and stool cultures. The clinical course was uneventful after starting appropriate rehydration and supportive therapy.
  9. Tan KK, Lee WS, Liaw LC, Oh A
    Singapore Med J, 1993 Apr;34(2):109-11.
    PMID: 8266145
    Two hundred and eleven blood transfusions were administered to 26 multi-transfused thalassemic children (aged 9 months-13 years) over a 6-month period. Eighteen children were receiving buffy coat-poor packed red cells (PRC) prepared by centrifuge while 8 children received filtered blood through a leucocyte-filter (Sepacell R-500A). Transfusion reactions occurred in 8.5% (n = 18) of transfusions and in 42.3% (n = 11) of patients. 11.9% (n = 16) and 2.6% (n = 2) of reactions occurred in 50% (n = 9) and 25% (n = 2) of patients receiving buffy coat-poor PRC and filtered blood respectively. Transfusion reactions in toto were significantly reduced in the group receiving filtered blood (p < 0.05). However, febrile reaction alone was not significantly reduced (p > 0.1). The median onset and duration of reaction were 2 hours (range 10 minutes-18 hours) and 4 hours (range 1/2-24 hours) respectively. 72.2% (n = 13) of the reactions occurred occurred during transfusion. 88.8% (n = 16) of the reactions caused only one symptom. 19.2% (n = 5) of all patients had recurrent reactions, all of them receiving buffy coat-poor PRC. The commonest clinical manifestation was fever (n = 7), followed by urticaria (n = 5) and petechial rash (n = 2). The outcome was good, with no patient experiencing symptoms exceeding 24 hours. Only 0.9% (n = 2) of the transfusions were discontinued.
  10. Tan JY, Wong JE, Zainal N, AbuBakar S, Tan KK
    J Vis Exp, 2023 Apr 07.
    PMID: 37092849 DOI: 10.3791/64578
    Zika virus (ZIKV) is a mosquito-borne virus belonging to the genus Flavivirus. ZIKV infection has been associated with congenital brain abnormalities and potentially Guillain-Barré syndrome in adults. Research on ZIKV to understand the disease mechanisms is important to facilitate vaccine and treatment development. The method of quantifying viruses is crucial and fundamental in the field of virology. The focus forming assay (FFA) is a virus quantification assay that detects the viral antigen with antibodies and identifies the infection foci of cells using the peroxidase immunostaining technique. The current study describes the virus propagation and quantification protocol using both 24-well and 96-well (high throughput) formats. Compared with other similar studies, this protocol has further described foci size optimization, which can serve as a guide to expand the use of this assay for other viruses. Firstly, ZIKV propagation is performed in Vero cells for 3 days. The culture supernatant containing ZIKV is harvested and quantitated using the FFA. Briefly, the virus culture is inoculated onto Vero cells and incubated for 2-3 days. Foci formation is then determined after optimized staining processes, including cell fixation, permeabilization, blocking, antibody binding, and incubation with peroxidase substrate. The stained virus foci are visualized using a stereo microscope (manual counting in 24-well format) or software analyzer (automated counting in 96-well format). The FFA provides reproducible, relatively fast results (3-4 days) and is suitable to be used for different viruses, including non-plaque-forming viruses. Subsequently, this protocol is useful for the study of ZIKV infection and could be used to detect other clinically important viruses.
  11. Wong JE, Zainal N, AbuBakar S, Tan KK
    J Vis Exp, 2023 May 05.
    PMID: 37212555 DOI: 10.3791/64887
    Endothelial cells line the inner surface of all blood and lymphatic vessels, creating a semi-permeable barrier regulating fluid and solute exchange between blood or lymph and their surrounding tissues. The ability of a virus to cross the endothelial barrier is an important mechanism that facilitates virus dissemination in the human body. Many viruses are reported to alter endothelial permeability and/or cause endothelial cell barrier disruption during infection, which is able to cause vascular leakage. The current study describes a real-time cell analysis (RTCA) protocol, using a commercial real-time cell analyzer to monitor endothelial integrity and permeability changes during Zika virus (ZIKV) infection of the human umbilical vein endothelial cells (HUVECs). The impedance signals recorded before and after ZIKV infection were translated to cell index (CI) values and analyzed. The RTCA protocol allows the detection of transient effects in the form of cell morphological changes during a viral infection. This assay could also be useful for studying changes in the vascular integrity of HUVECs in other experimental setups.
  12. Teoh BT, Sam SS, Tan KK, Johari J, Abd-Jamil J, Hooi PS, et al.
    Sci Rep, 2016 06 09;6:27663.
    PMID: 27278716 DOI: 10.1038/srep27663
    Timely and accurate dengue diagnosis is important for differential diagnosis and immediate implementation of appropriate disease control measures. In this study, we compared the usefulness and applicability of NS1 RDT (NS1 Ag Strip) and qRT-PCR tests in complementing the IgM ELISA for dengue diagnosis on single serum specimen (n = 375). The NS1 Ag Strip and qRT-PCR showed a fair concordance (κ = 0.207, p = 0.001). While the NS1 Ag Strip showed higher positivity than qRT-PCR for acute (97.8% vs. 84.8%) and post-acute samples (94.8% vs. 71.8%) of primary infection, qRT-PCR showed higher positivity for acute (58.1% vs. 48.4%) and post-acute (50.0% vs.41.4%) samples in secondary infection. IgM ELISA showed higher positivity in samples from secondary dengue (74.2-94.8%) than in those from primary dengue (21.7-64.1%). More primary dengue samples showed positive with combined NS1 Ag Strip/IgM ELISA (99.0% vs. 92.8%) whereas more secondary samples showed positive with combined qRT-PCR/IgM ELISA (99.4% vs. 96.2%). Combined NS1 Ag Strip/IgM ELISA is a suitable combination tests for timely and accurate dengue diagnosis on single serum specimen. If complemented with qRT-PCR, combined NS1 Ag Strip/IgM ELISA would improve detection of secondary dengue samples.
  13. Shamsul BS, Tan KK, Chen HC, Aminuddin BS, Ruszymah BH
    Tissue Cell, 2014 Apr;46(2):152-8.
    PMID: 24630213 DOI: 10.1016/j.tice.2014.02.001
    Autogenous bone graft is the gold standard for fusion procedure. However, pain at donor site and inconsistent outcome have left a surgeon to venture into some other technique for spinal fusion. The objective of this study was to determine whether osteogenesis induced bone marrow stem cells with the combination of ceramics granules (HA or TCP/HA), and fibrin could serve as an alternative to generate spinal fusion. The sheep's bone marrow mesenchymal stem cells (BMSCs) were aspirated form iliac crest and cultured for several passages until confluence. BMSCs were trypsinized and seeded on hydroxyapatite scaffold (HA) and tricalcium phosphate/hydroxyapatite (TCP/HA) for further osteogenic differentiation in the osteogenic medium one week before implantation. Six adult sheep underwent three-level, bilateral, posterolateral intertransverse process fusions at L1-L6. Three fusion sites in each animal were assigned to three treatments: (a) HA constructs group/L1-L2, (b) TCP/HA constructs group/L2-L3, and (c) autogenous bone graft group/L5-L6. The spinal fusion segments were evaluated using radiography, manual palpation, histological analysis and scanning electron microscopy (SEM) 12 weeks post implantation. The TCP/HA constructs achieved superior lumbar intertransverse fusion compared to HA construct but autogenous bone graft still produced the best fusion among all.
  14. Hss AS, Koh MT, Tan KK, Chan LG, Zhou L, Bouckenooghe A, et al.
    Vaccine, 2013 Dec 2;31(49):5814-21.
    PMID: 24135573 DOI: 10.1016/j.vaccine.2013.10.013
    Dengue disease is a major public health problem across the Asia-Pacific region for which there is no licensed vaccine or treatment. We evaluated the safety and immunogenicity of Phase III lots of a candidate vaccine (CYD-TDV) in children in Malaysia.
  15. Tan GH, Tan KK, Afian MS, Liew WF, Mohamad AR
    Med J Malaysia, 2005 Jul;60 Suppl C:111-3.
    PMID: 16381295
    We report a case of upper cervical instability associated with Down syndrome to highlight its potential progression to inflict cord compression and the rationale for surgical decompression and extended short segment occipito-axial fusion.
  16. Phang MY, Ng MH, Tan KK, Aminuddin BS, Ruszymah BH, Fauziah O
    Med J Malaysia, 2004 May;59 Suppl B:198-9.
    PMID: 15468886
    Tricalcium phosphate/hydroxyapatite (TCP/HA), hydroxyapatite (HA), chitosan and calcium sulphate (CaSO4) were studied and evaluated for possible bone tissue engineered construct acting as good support for osteogenic cells to proliferate, differentiate, and eventually spread and integrate into the scaffold. Surface morphology visualized by SEM showed that scaffold materials with additional fibrin had more cell densities attached than those without, depicting that the presence of fibrin and collagen fibers were truly a favourite choice of cells to attach. In comparison of various biomaterials used incorporated with fibrin, TCP/HA had the most cluster of cells attached.
  17. Tan KK, Aminuddin BS, Tan GH, Sabarul Afian M, Ng MH, Fauziah O, et al.
    Med J Malaysia, 2004 May;59 Suppl B:43-4.
    PMID: 15468810
    The strategy used to generate tissue-engineered bone construct, in view of future clinical application is presented here. Osteoprogenitor cells from periosteum of consenting scoliosis patients were isolated. Growth factors viz TGF-B2, bFGF and IGF-1 were used in concert to increase cell proliferation during in vitro cell expansion. Porous tricalcium phosphate (TCP)-hydroxyapatite (HA) scaffold was used as the scaffold to form 3D bone construct. We found that the addition of growth factors, greatly increased cell growth by 2 to 7 fold. TCP/HA proved to be the ideal scaffold for cell attachment and proliferation. Hence, this model will be further carried out on animal trial.
  18. Ng MH, Aminuddin BS, Tan KK, Tan GH, Sabarul Afian M, Ruszymah BH
    Med J Malaysia, 2004 May;59 Suppl B:41-2.
    PMID: 15468809
    Bone marrow stem cells (BMSC), known for its multipotency to differentiate into various mesenchymal cells such as chodrocyte, osteoblasts, adipocytes, etc, have been actively applied in tissue engineering. BMSC have been successfully isolated from bone marrow aspirate and bone marrow scraping from patients of various ages (13-56 years) with as little as 2ml to 5ml aspirate. BMSC isolated from our laboratory showed the presence of a heterogenous population that showed varying prevalence of surface antigens and the presence of telomerase activity albeit weak. Upon osteogenic induction, alkaline phosphatase activity and mineralization activity were observed.
  19. Wu DB, Roberts C, Lee VW, Hong LW, Tan KK, Mak V, et al.
    Hum Vaccin Immunother, 2016;12(2):403-16.
    PMID: 26451658 DOI: 10.1080/21645515.2015.1067351
    Pneumococcal disease causes large morbidity, mortality and health care utilization and medical and non-medical costs, which can all be reduced by effective infant universal routine immunization programs with pneumococcal conjugate vaccines (PCV). We evaluated the clinical and economic benefits of such programs with either 10- or 13-valent PCVs in Malaysia and Hong Kong by using an age-stratified Markov cohort model with many country-specific inputs. The incremental cost per quality-adjusted life year (QALY) was calculated to compare PCV10 or PCV13 against no vaccination and PCV13 against PCV10 over a 10-year birth cohort's vaccination. Both payer and societal perspectives were used. PCV13 had better public health and economic outcomes than a PCV10 program across all scenarios considered. For example, in the base case scenario in Malaysia, PCV13 would reduce more cases of IPD (+2,296), pneumonia (+705,281), and acute otitis media (+376,967) and save more lives (+6,122) than PCV10. Similarly, in Hong Kong, PCV13 would reduce more cases of IPD cases (+529), pneumonia (+172,185), and acute otitis media (+37,727) and save more lives (+2,688) than PCV10. During the same time horizon, PCV13 would gain over 74,000 and 21,600 additional QALYs than PCV10 in Malaysia and Hong Kong, respectively. PCV13 would be cost saving when compared against similar program with PCV10, under both payer and societal perspective in both countries. PCV13 remained a better choice over PCV10 in multiple sensitivity, scenario, and probabilistic analyses. PCV13s broader serotype coverage in its formulation and herd effect compared against PCV10 were important drivers of differences in outcomes.
  20. Ng KF, Tan KK, Ngui R, Lim YA, Amir A, Rajoo Y, et al.
    Asian Pac J Trop Med, 2015 Oct;8(10):878-80.
    PMID: 26522307 DOI: 10.1016/j.apjtm.2015.09.018
    We reported a case of amoebic liver abscess (ALA) in a 6-year-old Malaysian boy who presented with fever, lethargy, diarrhoea and right hypochondriac pain. On admission he was diagnosed with perforated acute appendicitis and a laparotomy was done. After surgery he developed acute respiratory distress. Ultrasonography, chest X-Ray and CT scan revealed two ALAs in the posterior segment of right lobe of liver, pleural effusion and collapsed consolidation of lungs bilaterally. Percutaneous liver abscesses drainage was done and intravenous Metronidazole was started. PCR carried out on the pus from the abscess was positive for Entamoeba histolytica. Patient however succumbed to the infection one week after admission.
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