Displaying publications 1 - 20 of 27 in total

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  1. Banavar SR, Rawal SY, Paterson IC, Singh G, Davamani F, Khoo SP, et al.
    Saudi Dent J, 2021 Nov;33(7):693-701.
    PMID: 34803321 DOI: 10.1016/j.sdentj.2020.04.007
    Mesenchymal stem cells (MSCs) are extensively used in tissue regenerative procedures. One source of MSCs is the periodontal ligament (PDL) of teeth. Isolation of MSCs from extracted teeth is reasonably simple, being less invasive and presenting fewer ethical concerns than does the harvesting of MSC's from other sites. The objectives of this study were to isolate and characterize the PDL stem cells (PDLSC) from healthy adults' extracted teeth and then to characterize them by comparing them with bone-marrow derived MSCs (BMMSC).

    Methods: The PDL tissue was scraped from the roots of freshly extracted teeth to enzymatically digest using collagenase. The cells were sub-cultured. Flow-cytometric analysis for the MSC surface-markers CD105, CD73, CD166, CD90, CD34, CD45 and HLA-DR was performed. To confirm the phenotype, total RNA was extracted to synthesize cDNA and which was then subjected to RT-PCR. The gene-expression for Oct4A, Sox2, NANOG and GAPDH was determined by gel-electrophoresis. To assess their multilineage potential, cells were cultured with osteogenic, chondrogenic and adipogenic medium and then stained by Alizarin-red, Alcian-blue and Oil-Red-O respectively. MSCs from the bone-marrow were processed similarly to serve as controls.

    Results: The cells isolated from extracted teeth expanded successfully. On flow-cytometric analysis, the cells were positive for CD73, CD90, CD105, CD166 and negative for CD34, CD45 and HLA-DR. The PDLSCs expressed Oct4A, Sox2, and NANOG mRNA with GAPDH expression. Cells cultured in the osteogenic, chondrogenic and adipogenic media stained positive for Alizarin-red, Alcian-blue and Oil- Red-O respectively. The surface marker expression and the trilineage differentiation characteristics were comparable to those of the BMMSCs.

    Conclusions: The periodontal ligament tissue of extracted teeth is a potential source of therapeutically useful MSCs. Harvesting them is not invasive and are a promising source of MSC as the PDLSCs showed characteristics similar to those of the highly regarded MSC's derived from bone-marrow.

  2. Chew MM, Gan SY, Khoo AS, Tan EL
    BMC Cancer, 2010;10:574.
    PMID: 20964870 DOI: 10.1186/1471-2407-10-574
    Nasopharyngeal carcinoma (NPC) is a type of neoplasm that is highly prevalent in East Asia and Africa with Epstein-Barr virus (EBV), genetic, and dietary factors implicated as possible aetiologic factors. Previous studies suggested the association of certain cytokines with the invasion and metastatic properties of NPC. The present study examined the roles of EBV latent membrane protein-1 (LMP1), interleukin-6 (IL-6), interleukin-10 (IL-10), transforming growth factor-beta 1 (TGF-β1) and laminin in the regulation of matrix-metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) in NPC. The effects of these factors on bmi-1, an oncogene, and ngx6, a tumour suppressor gene, were also investigated.
  3. Chin PS, Ang GY, Yu CY, Tan EL, Tee KK, Yin WF, et al.
    J Food Prot, 2018 Feb;81(2):284-289.
    PMID: 29360399 DOI: 10.4315/0362-028X.JFP-17-186
    Listeria spp. are ubiquitous in nature and can be found in various environmental niches such as soil, sewage, river water, plants, and foods, but the most frequently isolated species are Listeria monocytogenes and Listeria innocua. In this study, the presence of Listeria spp. in raw chicken meat and chicken-related products sold in local markets in Klang Valley, Malaysia was investigated. A total of 44 Listeria strains (42 L. innocua and 2 L. welshimeri) were isolated from 106 samples. Antibiotic susceptibility tests of the L. innocua strains revealed a high prevalence of resistance to clindamycin (92.9%), ceftriaxone (76.2%), ampicillin (73.8%), tetracycline (69%), and penicillin G (66.7%). Overall, 31 L. innocua and 1 L. welshimeri strain were multidrug resistant, i.e., nonsusceptible to at least one antimicrobial agent in three or more antibiotic classes. The majority of the L. innocua strains were placed into five AscI pulsogroups, and overall 26 distinct AscI pulsotypes were identified. The detection of multidrug-resistant Listeria strains from different food sources and locations warrants attention because these strains could serve as reservoirs for antimicrobial resistance genes and may facilitate the spread and emergence of other drug-resistant strains.
  4. Chong YP, Peter EP, Lee FJM, Chan CM, Chai S, Ling LPC, et al.
    Sci Rep, 2022 Jul 19;12(1):12315.
    PMID: 35853996 DOI: 10.1038/s41598-022-16671-9
    As pancreatic cancer cells (PCCs) and pancreatic stellate cells (PSCs) are the two major cell types that comprise the immunosuppressive tumor microenvironment of pancreatic cancer, we aimed to investigate the role of conditioned medium derived from PCCs and PSCs co-culture on the viability of lymphocytes. The conditioned medium (CM) collected from PCCs and/or PSCs was used to treat peripheral blood mononuclear cells (PBMCs) to determine CM ability in reducing lymphocytes population. A proteomic analysis has been done on the CM to investigate the differentially expressed protein (DEP) expressed by two PCC lines established from different stages of tumor. Subsequently, we investigated if the reduction of lymphocytes was directly caused by CM or indirectly via CM-induced MDSCs. This was achieved by isolating lymphocyte subtypes and treating them with CM and CM-induced MDSCs. Both PCCs and PSCs were important in suppressing lymphocytes, and the PCCs derived from a metastatic tumor appeared to have a stronger suppressive effect than the PCCs derived from a primary tumor. According to the proteomic profiles of CM, 416 secreted proteins were detected, and 13 DEPs were identified between PANC10.05 and SW1990. However, CM was found unable to reduce lymphocytes viability through a direct pathway. In contrast, CM that contains proteins secreted by PCC and/or PSC appear immunogenic as they increase the viability of lymphocytes subtypes. Lymphocyte subtype treated with CM-induced MDSCs showed reduced viability in T helper 1 (Th1), T helper 2 (Th2), and T regulatory (Treg) cells, but not in CD8+ T cells, and B cells. As a conclusion, the interplay between PCCs and PSCs is important as their co-culture displays a different trend in lymphocytes suppression, hence, their co-culture should be included in future studies to better mimic the tumor microenvironment.
  5. Gan SY, Wong LZ, Wong JW, Tan EL
    Int J Biol Macromol, 2019 Jan;121:207-213.
    PMID: 30300695 DOI: 10.1016/j.ijbiomac.2018.10.021
    Alzheimer's disease (AD) is a neurodegenerative disease that leads to progressive loss of neurons which often results in deterioration of memory and cognitive function. The development of AD is highly associated with the formation of senile plaques and neurofibrillary tangles. Amyloid β (Aβ) induces neurotoxicity and contributes to the development of AD. Recent evidences also highlighted the importance of neuroglobin (Ngb) in ameliorating AD. This study assessed the ability of fucosterol, a phytosterol found in brown alga, in protecting SH-SY5Y cells against Aβ-induced neurotoxicity. Its effects on the mRNA levels of APP and Ngb as well as the intracellular Aβ levels were also determined in Aβ-induced SH-SY5Y cells. SH-SY5Y cells were exposed to fucosterol prior to Aβ treatment. The effect on apoptosis was determined using Annexin V FITC staining and mRNA expression was studied using RT-PCR. Flow cytometry confirmed the protective effects of fucosterol on SH-SY5Y cells against Aβ-induced apoptosis. Pretreatment with fucosterol increased the Ngb mRNA levels but reduced the levels of APP mRNA and intracellular Aβ in Aβ-induced SH-SY5Y cells. These observations demonstrated the protective properties of fucosterol against Aβ-induced neurotoxicity in neuronal cells.
  6. Ho SL, Tan EL, Sam CK, Goh KL
    J Dig Dis, 2010 Apr;11(2):101-5.
    PMID: 20402836 DOI: 10.1111/j.1751-2980.2010.00423.x
    To determine the prevalence of primary clarithromycin resistance amongst Helicobacter pylori (H. pylori) strains in Malaysian patients with gastroduodenal diseases, by using restriction fragment length polymorphism (RFLP) in domain V of 23S rRNA.
  7. Kan CY, H'ng JX, Goh A, Smales F, Tan EL, Zhang S, et al.
    Int Dent J, 2023 Feb;73(1):63-70.
    PMID: 35725589 DOI: 10.1016/j.identj.2022.04.011
    OBJECTIVE: This study aimed to evaluate the effect of methanol (70% v/v), ethanol (80% v/v), dimethyl sulfoxide (DMSO; 100% v/v) extracts of ginger rhizome (GR), and 6-shogaol on the pilocarpine-stimulated salivary flow rate in C57BL/6 mice.

    METHODS: Three extracts of ginger (Zingiber officinale) rhizome prepared by maceration using the respective solvents and 6-shogoal were reconstituted in normal saline with 0.2% DMSO. Thirty C57BL/6 15-week-old mice were divided into 5 groups: Group 1, saline; Group 2, 70% methanol extract; Group 3, 80% ethanol extract; Group 4, 100% DMSO extract; and Group 5, 6-shogaol. The baseline pilocarpine-stimulated salivary flow rate was measured at the age of 15 weeks (15th week), and treatment solutions were administered by intraperitoneal injection from the 16th to 18th week. The stimulated salivary flow rate during treatment weeks was recorded for each group, and its difference with baseline was analysed using paired-sample t test. The change in salivary flow rate between the treatment groups and the control group was analysed using one-way analysis of variance.

    RESULTS: Groups 2, 3, 4, and 5 showed a significant increase in salivary flow rate when compared to baseline (P < .05). The increase in salivary flow rate in all 4 treatment groups was significant when compared to the control group (P < .05). Group 4 produced the highest increase in salivary flow rate; however, the differences amongst the treatment groups did not reach statistical significance (P > .05).

    CONCLUSIONS: All GR extracts (70% methanol, 80% ethanol, 100% DMSO) and 6-shogaol were equally effective in increasing the pilocarpine-stimulated salivary flow rate in C57BL/6 mice when administered systemically as a sustained dose for 3 weeks.

  8. Kong DC, Chew KY, Tan EL, Khoo SP
    Cancer Cell Int, 2014;14:65.
    PMID: 25866477 DOI: 10.1186/1475-2867-14-65
    Epiregulin (EPR) is a novel member of the epidermal growth factor (EGF) family. It has been shown to promote wound healing in oral epithelium, enhance proliferation of other epithelial tissues, and is involved in several epithelial-related malignancies such as colorectal, lung, and bladder carcinoma. More recently, EPR transcripts were found to be high in a study on archival oral squamous cell carcinoma (OSCC) specimens. This implies that EPR may be responsible for the progression of OSCC. The aim of this was to elucidate the effects of EPR on (i) cell morphological changes, (ii) cell proliferation and (iii) receptor expression of the H-series OSCC cell lines.
  9. Lai NM, Tan ML, Quah SY, Tan EL, Foong KW
    Singapore Med J, 2010 Sep;51(9):724-9.
    PMID: 20938614
    We conducted a retrospective audit on the inpatient assessment and care of children admitted with febrile convulsion to Hospital Batu Pahat, a district hospital in Malaysia, using the Malaysian national clinical practice guidelines and the American Academy of Paediatrics practice parameters on febrile convulsion as the reference standards.
  10. Lee LK, Tan EL, Gopala K, Sam CK
    Singapore Med J, 2007 Jul;48(7):632-4.
    PMID: 17609824
    Nasopharyngeal carcinoma (NPC) is the second most common cancer among Malaysian Chinese males. We determined the frequencies of 17 human leukocyte antigens (HLA), HLA-A and HLA-B, alleles in 88 Malaysian Chinese with NPC.
  11. Lim PC, Tan HH, Mohd Noor NA, Chang CT, Wong TY, Tan EL, et al.
    J Pharm Policy Pract, 2023 Jul 05;16(1):83.
    PMID: 37408067 DOI: 10.1186/s40545-023-00583-8
    BACKGROUND: Pharmacist's involvement in optimizing medication adherence among diabetic patients has been implemented for over a decade. Diabetes Medication Therapy Adherence Clinic (DMTAC) was set up to educate diabetic patients, monitor treatment outcomes, and manage drug-related problems. While evidence shows that pharmacist-led DMTAC was effective in reducing HbA1c, there was limited data regarding the impact of different intervention types and default to follow-up on glycemic control.

    AIM: To assess the impact DMTAC on glycemic control and the difference in glycemic control between hospital and health clinic settings as well as defaulter and non-defaulter. In addition, the impact of pharmacist's interventions, DMTAC follow-up frequencies, and duration of diabetes on glycemic control were also determined.

    METHODS: A retrospective study was conducted among diabetes patients under DMTAC care between January 2019 and June 2020 in five hospitals and 23 primary health clinics. Patients' demographics data, treatment regimens, frequencies of DMTAC visits, defaulter (absent from DMTAC visits) and types of pharmacists' intervention were retrieved from patients' medical records and electronic database. HbA1c was collected at baseline, 4-6 months (post-1), and 8-12 months (post-2).

    RESULTS: We included 956 patients, of which 60% were females with a median age of 58.0 (IQR: 5.0) years. Overall, the HbA1c reduced significantly from baseline (median: 10.2, IQR: 3.0) to post-1 (median: 8.8, IQR: 2.7) and post-2 (median: 8.3, IQR: 2.6%) (p 

  12. Ong LY, Pang T, Lim SH, Tan EL, Puthucheary SD
    J Med Microbiol, 1989 Jul;29(3):195-8.
    PMID: 2473209
    A simple adherence test to detect IgM antibodies in patients with typhoid is described. The test utilises the IgM-"capture" approach, in which the test serum is applied to microtitration plate wells previously coated with anti-human IgM, followed by application of a stained Salmonella typhi antigen suspension which shows adherence in positive cases. By this test, 58 (95%) of 61 sera from confirmed cases of typhoid possessed IgM antibodies to the H or O or both antigens of S. typhi. In patients for whom a diagnosis of typhoid was based only on a significant Widal-test titre, 31 (41%) of 76 sera had IgM antibodies to the H or O or both antigens of S. typhi. Some cross-reactivity of the IgM antibodies was detected, especially with the O antigens of S. paratyphi A and B. A total of 82 sera from non-typhoidal fevers (leptospirosis, typhus, dengue fever) showed no reactivity in this test. In normal sera there was no detectable IgM to the O antigen of S. typhi and only a small number (3.9%) had low levels of IgM to the H antigen. The significance and potential importance of this simple, sensitive, specific and economical test is discussed.
  13. Poh CL, Tan EL
    Methods Mol Biol, 2011;665:65-77.
    PMID: 21116796 DOI: 10.1007/978-1-60761-817-1_5
    Enteroviruses are positive stranded RNA viruses belonging to the genus Enterovirus of the Picornaviridae family. Human enteroviruses are transmitted through the fecal-oral route and have been shown to cause mild to life-threatening diseases. Various diagnostic methods have been developed to detect enteroviruses from clinical specimens but many were impeded by requirements for special reagents, lengthy procedures, low sensitivity or cross-reactivity. This chapter describes rapid and highly sensitive methods of enteroviral detection directly from clinical specimens based on a conventional one-step Reverse Transcription polymerase chain reaction (RT-PCR) and a one-step real-time RT-PCR.
  14. Poh YW, Gan SY, Tan EL
    Exp Oncol, 2012 Jul;34(2):85-9.
    PMID: 23013758
    The aim of this study is to investigate whether IL-6, IL-10 and TGF-β are able to confer resistance to apoptosis in nasopharyngeal carcinoma cells by upregulating the expression of survivin.
  15. Soo CI, Ng BH, Tan EL, Abdul Hamid F
    SAGE Open Med Case Rep, 2016;4:2050313X16650323.
    PMID: 27489719 DOI: 10.1177/2050313X16650323
    Pulmonary epithelioid hemangioendothelioma is an uncommon lung malignancy of endothelial origin. Besides demonstrating unpredictable presentation features and prognosis, the paucity of established treatment guidelines remains a challenge in managing these patients. We present two patients. The first patient presented with chronic productive cough over 1-year duration. He was initially diagnosed and showed partial response to treatment for cardiac failure. A persistent right upper zone consolidation on chest radiograph prompted further investigations which revealed the diagnosis of pulmonary epithelioid hemangioendothelioma. The second patient presented with right-sided hemiparesis for 1-month duration. Initial computer tomography scan of the brain showed findings of distant metastatic foci. Subsequent investigations revealed pulmonary epithelioid hemangioendothelioma as the primary lesion. Both patients succumbed without any treatment due to rapid progression of the disease. We believe that pulmonary epithelioid hemangioendothelioma is undoubtedly rarely reported in south-east Asia region. In these two case reports, the patients were diagnosed in west and east Malaysia, respectively, in the same year (2015). Both cases highlight the increasing prevalence of pulmonary epithelioid hemangioendothelioma. We postulate that this could possibly be secondary to the advancement in diagnostic capabilities and improved healthcare facilities available in this region. Late presentation of pulmonary epithelioid hemangioendothelioma generally results in grave prognosis. Further investigations are required to elucidate the nature of progression and therapeutic options for patients with pulmonary epithelioid hemangioendothelioma.
  16. Tan CW, Chan YF, Sim KM, Tan EL, Poh CL
    PLoS One, 2012;7(5):e34589.
    PMID: 22563456 DOI: 10.1371/journal.pone.0034589
    Enterovirus 71 (EV-71) is the main causative agent of hand, foot and mouth disease (HFMD). In recent years, EV-71 infections were reported to cause high fatalities and severe neurological complications in Asia. Currently, no effective antiviral or vaccine is available to treat or prevent EV-71 infection. In this study, we have discovered a synthetic peptide which could be developed as a potential antiviral for inhibition of EV-71. Ninety five synthetic peptides (15-mers) overlapping the entire EV-71 capsid protein, VP1, were chemically synthesized and tested for antiviral properties against EV-71 in human Rhabdomyosarcoma (RD) cells. One peptide, SP40, was found to significantly reduce cytopathic effects of all representative EV-71 strains from genotypes A, B and C tested, with IC(50) values ranging from 6-9.3 µM in RD cells. The in vitro inhibitory effect of SP40 exhibited a dose dependent concentration corresponding to a decrease in infectious viral particles, total viral RNA and the levels of VP1 protein. The antiviral activity of SP40 peptide was not restricted to a specific cell line as inhibition of EV-71 was observed in RD, HeLa, HT-29 and Vero cells. Besides inhibition of EV-71, it also had antiviral activities against CV-A16 and poliovirus type 1 in cell culture. Mechanism of action studies suggested that the SP40 peptide was not virucidal but was able to block viral attachment to the RD cells. Substitutions of arginine and lysine residues with alanine in the SP40 peptide at positions R3A, R4A, K5A and R13A were found to significantly decrease antiviral activities, implying the importance of positively charged amino acids for the antiviral activities. The data demonstrated the potential and feasibility of SP40 as a broad spectrum antiviral agent against EV-71.
  17. Tan EL, Selvaratnam G, Kananathan R, Sam CK
    BMC Cancer, 2006;6:227.
    PMID: 16995954
    Nasopharyngeal carcinoma (NPC) is a common epithelial neoplasm among the Chinese populations in Southern China and South East Asia. Epstein-Barr virus (EBV) is known to be an important etiologic agent of NPC and the viral gene products are frequently detected in NPC tissues along with elevated antibody titres to the viral proteins (VCA and EA) in a majority of patients. Elevated plasma EBV DNA load is regarded as an important marker for the presence of the disease and for the monitoring of disease progression. However, other serum/plasma parameters such as the levels of certain interleukins and growth factors have also been implicated in NPC. The objectives of the present study are, 1) to investigate the correlations between plasma EBV DNA load and the levels of interleukin (IL)-6, IL-10, TGF-beta1 and SCF (steel factor) and 2) to relate these parameters to the stages of NPC and the effect of treatment.
  18. Tan EL, Peh SC, Sam CK
    J Med Virol, 2003 Feb;69(2):251-7.
    PMID: 12683415
    Nasopharyngeal carcinoma, a malignancy associated closely with Epstein-Barr virus (EBV), is prevalent among Chinese of Southern China origin. Epidemiological studies indicate a high prevalence of EBV in Asia with viral isolates having typical characteristics of the putative viral oncogene, latent membrane protein 1 (LMP-1), such as the loss of the Xho1 restriction site in Exon 1 and the 30-bp deletion in Exon 3. The EBV LMP-1 gene from throat washings of 120 nasopharyngeal carcinoma patients and 14 healthy individuals were analyzed. Similar analyses were also carried out on 30 and 12 postnasal space biopsies from nasopharyngeal carcinoma patients and healthy individuals, respectively. The 30-bp deletion was detected in 20% of nasopharyngeal carcinoma throat washes and in 100% of nasopharyngeal carcinoma postnasal space biopsies. Interestingly, 16% of the nasopharyngeal carcinoma biopsies possessed both the deleted and the undeleted variants, suggestive of dual infections. The notion of dual infections in nasopharyngeal carcinoma was further supported by the coexistence of both "F" and "f" (BamH1F region) EBV variants in 11% of the nasopharyngeal carcinoma biopsies. All of the throat washes and biopsies from the healthy controls showed the undeleted variant. The loss of the Xho1 restriction site was found with higher frequency both in throat washes and biopsies from patients with nasopharyngeal carcinoma. The discrepancy in the frequency of the 30-bp deletion between throat washes (20%) and postnasal space biopsies (100%) was an indication that this deletion is specific for viral isolates from primary tumour sites.
  19. Tan EL, Sam CK
    Exp Oncol, 2007 Sep;29(3):166-74.
    PMID: 18004239
    Epstein-Barr virus (EBV), a human gammaherpesvirus is intimately associated with nasopharyngeal carcinoma (NPC), with the incidence of the virus detected in malignant tissues being close to 100% in NPC endemic areas. The viral latent gene, latent membrane protein 1 (LMP1), has all the typical characteristics of an oncogene and extensive studies have shown beyond doubt its abilities in cellular transformation giving rise to malignant phenotypes. The present study compares the gene sequence and biological properties of LMP1 gene derived from two patients with different stages of NPC--one presented with dysplastic, pre-malignant lesion and the other with malignant lesion.
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