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  1. Khoo, Suan Phaik
    Ann Dent, 1995;2(1):-.
    MyJurnal
    The ability of a pathologist to accurately interpret a lesion is largely dependent on a good biopsy performed by the surgeon. This article describes the common pittfalls in biopsy techniques and offers ways to minimize them. It also discusses the difficulties encountered by the pathologist in attempting to interpret artefactually damaged tissues.
  2. Khoo, Suan Phaik, Jalil, N., Yaacob, H.B.
    Ann Dent, 1997;4(1):-.
    MyJurnal
    The calcifying epithelial odontogenic tumour (CEOT) is a rare benign odontogenic neoplasm which was first described by Pindborg in 1955. It accounts for less than 1% of all odontogenic lesions. A case of CEOT which presented together with cardiac abnomlalities is presented here and the literature of CEOT is reviewed.
  3. Khoo SP
    Family Physician, 1994;6:2-5.
    Temporomandibular disorders are the commonest orofacila pain. Many of them present themselves to the primary care physician. A fundamental familiarity with this disorder is essential for proper diagnosis and management.
  4. Khoo, Suan Phaik, Shanmuhasuntharam, P., Mahadzir, W.M., Tay, K.K., Latif, A., Nair, S.
    Ann Dent, 1996;3(1):-.
    MyJurnal
    The diagnosis of oral cancer have been variously reported as being due to delay by clinicians, patients or both. The purpose of this study was to evaluate the referral pattern of 65 patients eventually diagnosed as having oral squamous cell carcinoma. The results showed that 50% of the patients delayed seeking professional help for more than 3 months after being aware of the lesion. The majority of the patients consulted medical practitioners as the first source of help. The mean clinicians' and patients' delay were 10.3 weeks and 28.9 weeks respectively. Dental practitioners showed a tendency to refer on more advanced lesions compared to the medical practitioners. The findings raise the concern that lack of patients' awareness, misdiagnosis by clinicians and late detection by dental practitioners prevail thus calling for urgent measures towards early detection of the disease.
  5. Khoo SP, Lee, K.W.
    Ann Dent, 1995;2(1):-.
    MyJurnal
    A study was carried out to investigate whether smoking had any effect on the Langerhans cells in the oral mucosa, which might throw light onto the mechanism of malignant transformation of some keratotic lesions in the oral cavity. Thirty-two cases of keratotic lesions from biopsy specimens of smokers and non-smokers were studied. Langerhans cells were identified by immuno cytochemical staining for 5100 proteins and their densities quantified. Smokers were associated with a significant reduction in the Langerhans cell population compared to non-smokers. The mean values of Langellans cell density in light smokers and heavy smokers were 2 2 2 28.64/mm and 33.421mm respectively compared to 66.51/mm in non- smokers. There was a dose-response relation between the number of cigarettes smoked daily and the effect on cell counts. These findings of a local immunological effect of smoking on oral epithelium may explain the means by which cigarette smoking contributes to the development of oral cancer.
  6. Khoo SP, Ong ST
    Ann Dent, 1998;5(1):49-52.
    MyJurnal
    Odontogenic carcinomas of the jaws are subclassified into malignant ameloblastoma, ameloblastic carcinoma and primary intraosseous carcinoma arising from within the bone. These may arise from residual islands of epithelium derived from dental lamina or epithelial lining of dental cysts. Ameloblastic carcinoma is extremely rare. An aggressive case of ameloblastic carcinoma occumng in a 59-year-old Malay man is presented. Wide excision of the primary lesion with radical neck dissection was carried out. He developed lung metastasis 4 months post-operatively. Despite chemotherapy upon discovery of lung metastasis, he expired 7 months following the initial diagnosis.
  7. Menke JM, Ahsan MS, Khoo SP
    Biomark Cancer, 2017;9:1179299X17732007.
    PMID: 29085239 DOI: 10.1177/1179299X17732007
    Signal detection and Bayesian inferential tools were applied to salivary biomarkers to improve screening accuracy and efficiency in detecting oral squamous cell carcinoma (OSCC). Potential cancer biomarkers are identified by significant differences in assay concentrations, receiver operating characteristic areas under the curve (AUCs), sensitivity, and specificity. However, the end goal is to report to individual patients their risk of having disease given positive or negative test results. Likelihood ratios (LRs) and Bayes factors (BFs) estimate evidential support and compile biomarker information to optimize screening accuracy. In total, 26 of 77 biomarkers were mentioned as having been tested at least twice in 137 studies and published in 16 summary papers through 2014. Studies represented 10 212 OSCC and 25 645 healthy patients. The measure of biomarker and panel information value was number of biomarkers needed to approximate 100% positive predictive value (PPV). As few as 5 biomarkers could achieve nearly 100% PPV for a disease prevalence of 0.2% when biomarkers were ordered from highest to lowest LR. When sequentially interpreting biomarker tests, high specificity was more important than test sensitivity in achieving rapid convergence toward a high PPV. Biomarkers ranked from highest to lowest LR were more informative and easier to interpret than AUC or Youden index. The proposed method should be applied to more recently published biomarker data to test its screening value.
  8. Khoo SP, Yap AU, Chan YH, Bulgiba AM
    J Orofac Pain, 2008;22(2):131-8.
    PMID: 18548842
    To develop a Malay-language version of the Axis II Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) through a formal translation/back-translation process and to summarize available data about the psychometric properties of the translated scales.
  9. 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.
  10. 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.

  11. Bapat RA, Mak KK, Pichika MR, Pang JC, Lin SL, Khoo SP, et al.
    BMC Oral Health, 2024 Mar 25;24(1):382.
    PMID: 38528501 DOI: 10.1186/s12903-024-04069-0
    AIMS AND OBJECTIVES: To analyze anti-MMP mode of action of Quaternary Ammonium Silane (QAS, codenamed as k21) by binding onto specific MMP site using computational molecular simulation and Anti-Sortase A (SrtA) mode of action by binding onto specific site using computational molecular simulation.

    MATERIALS AND METHODS: In silico Molecular Dynamics (MD) was used to determine the interactions of K21 inside the pocket of the targeted protein (crystal structure of fibroblast collagenase-1 complexed to a diphenyl-ether sulphone based hydroxamic acid; PDB ID: 966C; Crystal structure of MMP-2 active site mutant in complex with APP-derived decapeptide inhibitor. MD simulations were accomplished with the Desmond package in Schrödinger Drug Discovery Suite. Blood samples (~ 0.5 mL) collected into K2EDTA were immediately transferred for further processing using the Litron MicroFlow® PLUS micronucleus analysis kit for mouse blood according to the manufacturer's instructions. Bacterial Reverse Mutation Test of K21 Molecule was performed to evaluate K21 and any possible metabolites for their potential to induce point mutations in amino acid-requiring strains of Escherichia coli (E. coli) (WP2 uvrA (tryptophan-deficient)).

    RESULTS: Molecular Simulation depicted that K21 has a specific pocket binding on various MMPs and SrtA surfaces producing a classical clouting effect. K21 did not induce micronuclei, which are the result of chromosomal damage or damage to the mitotic apparatus, in the peripheral blood reticulocytes of male and female CD-1 mice when administered by oral gavage up to the maximum recommended dose of 2000 mg/kg. The test item, K21, was not mutagenic to Salmonella typhimurium (S. typhimurium) strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the absence and presence of metabolic activation when tested up to the limit of cytotoxicity or solubility under the conditions of the test.

    CONCLUSION: K21 could serve as a potent protease inhibitor maintaining the physical and biochemical properties of dental structures.

  12. Verusingam ND, Yeap SK, Ky H, Paterson IC, Khoo SP, Cheong SK, et al.
    PeerJ, 2017;5:e3174.
    PMID: 28417059 DOI: 10.7717/peerj.3174
    Although numbers of cancer cell lines have been shown to be successfully reprogrammed into induced pluripotent stem cells (iPSCs), reprogramming Oral Squamous Cell Carcinoma (OSCC) to pluripotency in relation to its cancer cell type and the expression pattern of pluripotent genes under later passage remain unexplored. In our study, we reprogrammed and characterised H103 and H376 oral squamous carcinoma cells using retroviral OSKM mediated method. Reprogrammed cells were characterized for their embryonic stem cells (ESCs) like morphology, pluripotent gene expression via quantitative real-time polymerase chain reaction (RT-qPCR), immunofluorescence staining, embryoid bodies (EB) formation and directed differentiation capacity. Reprogrammed H103 (Rep-H103) exhibited similar ESCs morphologies with flatten cells and clear borders on feeder layer. Reprogrammed H376 (Rep-H376) did not show ESCs morphologies but grow with a disorganized morphology. Critical pluripotency genes Oct4, Sox2 and Nanog were expressed higher in Rep-H103 against the parental counterpart from passage 5 to passage 10. As for Rep-H376, Nanog expression against its parental counterpart showed a significant decrease at passage 5 and although increased in passage 10, the level of expression was similar to the parental cells. Rep-H103 exhibited pluripotent signals (Oct4, Sox2, Nanog and Tra-1-60) and could form EB with the presence of three germ layers markers. Rep-H103 displayed differentiation capacity into adipocytes and osteocytes. The OSCC cell line H103 which was able to be reprogrammed into an iPSC like state showed high expression of Oct4, Sox2 and Nanog at late passage and may provide a potential iPSC model to study multi-stage oncogenesis in OSCC.
  13. Keong JY, Low LW, Chong JM, Ong YY, Pulikkotil SJ, Singh G, et al.
    Saudi Dent J, 2020 Mar;32(3):148-154.
    PMID: 32180672 DOI: 10.1016/j.sdentj.2019.08.001
    PURPOSE: Periodontal ligament stem cells (PDLSCs) have considerable potential for use as a means of achieving periodontal regeneration due to their noteworthy proliferative properties and secretory functions. In particular, PDLSCs secrete vascular endothelial growth factor (VEGF) which enhances angiogenesis and osteogenesis. The resulting repair and development of blood vessels and hard tissues which would occur in the presence of these cells could be central to an effective periodontal regeneration procedure.The bacterial biofilm of tooth surface related to the periodontium might provide either an inhibition or a stimulus to different factors involved in a regenerative process. Cell culture experiments have been investigated in vitro by adding lipopolysaccharide (LPS) to the culture medium but the effect of various concentration of LPS in these circumstances has not been investigated. Therefore, this study aimed to investigate the effect of LPS concentrations on proliferation of PDLSCs in vitro and on their secretion of VEGF.

    MATERIALS AND METHODS: PDLSCs were treated with 0, 5, 10 and 20 µg/mL of Escherichia coli LPS. At 48 and 96 h, total cell numbers of control and LPS treated PDLSCs were counted by haemocytometer under a microscope. The VEGF concentration in the conditioned media of the PDLSCs was measured by ELISA.

    RESULTS: Rate of cell proliferation of PDLSCs decreased significantly in all LPS treated groups at both 48 h and 96 h except for the group treated with 5 µg/mL of LPS at 48 h. At both 48 and 96 h, VEGF secretion from PDLSCs was reduced significantly at all three LPS concentrations. There was no statistically significant difference in cell proliferation and the amount of VEGF secretion of PDLSCs among the groups treated with different LPS concentrations. No statistically significant change was found in cell proliferation of LPS treated PDLSCs over time, whereas VEGF secretion of PDLSCs was found to have increased significantly with time despite the LPS treatment.

    CONCLUSIONS: LPS reduced cell proliferation and VEGF secretion of PDLSCs, suggesting that periodontal pathogens might reduce the capability of PDLSCs in periodontal regeneration. Yet, LPS treated PDLSCs remained viable and VEGF secretion increased significantly over time. Further research is needed to study the potential use of PDLSCs in periodontal regeneration and the relationship of biofilm LPS accumulations.

  14. Maharajan MK, Rajiah K, Khoo SP, Chellappan DK, De Alwis R, Chui HC, et al.
    PLoS One, 2017;12(1):e0168863.
    PMID: 28060838 DOI: 10.1371/journal.pone.0168863
    OBJECTIVES: To evaluate the attitudes and readiness of students of healthcare professions towards interprofessional learning.

    METHODOLOGY: A cross-sectional study design was used. Two different scales were used to measure the readiness for and perception of interprofessional learning; these were the 'Readiness for Interprofessional Learning Scale' and the 'Interdisciplinary Education Perception Scale'. A convenience sampling method was employed. The sample was drawn from undergraduate students enrolled in years 1 to 5 of medical, dental, pharmacy and health sciences programme. Descriptive and inferential statistics were used to analyse the data.

    RESULTS: The overall response rate was 83%. The students mentioned that shared learning with other healthcare professional students will increase their ability to understand clinical problems. The students also mentioned that such shared learning will help them to communicate better with patients and other professionals. The students preferred to work with individuals from their own profession. Participants from medical, dental, pharmacy, and health sciences had a difference in opinion about 'negative professional identity', a domain of the Readiness for Interprofessional Learning Scale. Based on the different year of study of the students, 'team work and collaboration', 'negative professional identity' and 'roles and responsibility' were the Interdisciplinary Education Perception Scale domains where students had a difference in opinion.

    CONCLUSIONS: Attitudes and readiness towards interprofessional learning showed significant differences among students of various healthcare professions; these differences also depended on the students' year of study. Interprofessional learning should be incorporated in the curriculum of all healthcare professional programs, which may foster students to become competent healthcare providers and understand each profession's role.

  15. Zwiri A, Al-Hatamleh MAI, W Ahmad WMA, Ahmed Asif J, Khoo SP, Husein A, et al.
    Diagnostics (Basel), 2020 May 15;10(5).
    PMID: 32429070 DOI: 10.3390/diagnostics10050303
    Numerous studies have been conducted in the previous years with an objective to determine the ideal biomarker or set of biomarkers in temporomandibular disorders (TMDs). It was recorded that tumour necrosis factor (TNF), interleukin 8 (IL-8), IL-6, and IL-1 were the most common biomarkers of TMDs. As of recently, although the research on TMDs biomarkers still aims to find more diagnostic agents, no recent study employs the biomarker as a targeting point of pharmacotherapy to suppress the inflammatory responses. This article represents an explicit review on the biomarkers of TMDs that have been discovered so far and provides possible future directions towards further research on these biomarkers. The potential implementation of the interactions of TNF with its receptor 2 (TNFR2) in the inflammatory process has been interpreted, and thus, this review presents a new hypothesis towards suppression of the inflammatory response using TNFR2-agonist. Subsequently, this hypothesis could be explored as a potential pain elimination approach in patients with TMDs.
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