Displaying publications 61 - 80 of 109 in total

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  1. Abdul Rahman H, Manzor NF, Tan GC, Tan AE, Chua KH
    Med J Malaysia, 2008 Jul;63 Suppl A:57-8.
    PMID: 19024982
    Angiogenic induction was made to promote angiogenesis by differentiating stem cells towards endothelial cells. However, the stemness property of induced cells has not been revealed yet. Hence, we aim to evaluate the differential mRNA expression of stemness genes in human chorion-derived stem cells (CDSC) after being cultured in EDM50 comprised bFGF and VEGF. Results indicated that CDSC cultured in EMD50 expressed significantly higher mRNA level of Sox-2, FZD9, BST-1 and Nestin. In addition Oct-4, FGF-4 and ABCG-2 were also upregulated. Our finding suggested that CDSC after angiogenic induction enhanced its stem cell properties. This could be contributed for the mechanism of stem cell therapy in ischemic problem.
  2. Fatimah SS, Tan GC, Chua K, Tan AE, Nur Azurah AG, Hayati AR
    Burns, 2013 Aug;39(5):905-15.
    PMID: 23273814 DOI: 10.1016/j.burns.2012.10.019
    The aim of the present study was to determine the effects of KGF on the differentiation of cultured human amnion epithelial cells (HAECs) towards skin keratinocyte. HAECs at passage 1 were cultured in medium HAM's F12: Dulbecco's Modified Eagles Medium (1:1) supplemented with different concentrations of KGF (0, 5, 10, 20, 30 and 50 ng/ml KGF). Dose-response of KGF on HAECs was determined by morphological assessment; growth kinetic evaluation; immunocytochemical analysis; stemness and epithelial gene expression quantification with two step real time RT-PCR. KGF promotes the proliferation of HAECs with maximal effect observed at 10 ng/ml KGF. However, KGF decreased the stemness genes expression: Oct-3/4, Sox-2, Nanog3, Rex-1, FGF-4, FZD-9 and BST-1. KGF also down-regulates epithelial genes expression: CK3, CK18, CK19, Integrin-β1, p63 and involucrin in cultured HAECs. No significant difference on the gene expression was detected for each Nestin, ABCG-2, CK1 and CK14 in KGF-treated HAECs. Immunocytochemical analysis for both control and KGF-treated HAECs demonstrated positive staining against CK14 and CK18 but negative staining against involucrin. The results suggested that KGF stimulates an early differentiation of HAECs towards epidermal cells. Differentiation of KGF-treated HAECs to corneal lineage is unfavourable. Therefore, further studies are needed to elucidate the roles of KGF in the differentiation of HAECs towards skin keratinocytes.
  3. Hayati AR, Nur Fariha MM, Tan GC, Tan AE, Chua K
    Arch Med Res, 2011 May;42(4):291-300.
    PMID: 21820607 DOI: 10.1016/j.arcmed.2011.06.005
    Placenta as a fetomaternal organ is a potential source of fetal as well as maternal stem cells. This present study describes novel properties of the cells isolated from the maternal part of term placenta membrane, the decidua basalis.
  4. Gwee CP, Khoo CH, Yeap SK, Tan GC, Cheah YK
    PeerJ, 2019;7:e5989.
    PMID: 30671294 DOI: 10.7717/peerj.5989
    The fight against cancer has been a never-ending battle. Limitations of conventional therapies include lack of selectivity, poor penetration and highly toxic to the host. Using genetically modified bacteria as a tumour therapy agent has gained the interest of scientist from the past few decades. Low virulence and highly tolerability of Salmonella spp. in animals and humans make it as the most studied pathogen with regards to anti-tumour therapy. The present study aims to construct a genetically modified S. Agona auxotroph as an anti-tumour agent. LeuB and ArgD metabolic genes in ΔSopBΔSopD double knockout S. Agona were successfully knocked out using a Targetron gene knockout system. The knockout was confirmed by colony PCR and the strains were characterized in vitro and in vivo. The knockout of metabolic genes causes significant growth defect in M9 minimal media. Quadruple knockout ΔSopBΔSopDΔLeuBΔArgD (BDLA) exhibited lowest virulence among all of the strains in all parameters including bacterial load, immunity profile and histopathology studies. In vivo anti-tumour study on colorectal tumour bearing-BALB/c mice revealed that all strains of S. Agona were able to suppress the growth of the large solid tumour as compared with negative control and ΔLeuBΔArgD (LA) and BDLA auxotroph showed better efficacy. Interestingly, higher level of tumour growth suppression was noticed in large tumour. However, multiple administration of bacteria dosage did not increase the tumour suppression efficacy. In this study, the virulence of BDLA knockout strain was slightly reduced and tumour growth suppression efficacy was successfully enhanced, which provide a valuable starting point for the development of S. Agona as anti-tumour agent.
  5. Liew LC, Gailhouste L, Tan GC, Yamamoto Y, Takeshita F, Nakagama H, et al.
    Stem Cells, 2020 04;38(4):504-515.
    PMID: 31828873 DOI: 10.1002/stem.3136
    The role of microRNAs (miRNAs) during mouse early development, especially in endoderm germ layer formation, is largely unknown. Here, via miRNA profiling during endoderm differentiation, we discovered that miR-124a negatively regulates endoderm lineage commitment in mouse embryonic stem cells (mESCs). To further investigate the functional role of miR-124a in early stages of differentiation, transfection of embryoid bodies with miR-124a mimic was performed. We showed that overexpression of miR-124a inhibits endoderm differentiation in vitro through targeting the 3'-untranslated region (UTR) of Sox17 and Gata6, revealing the existence of interplay between miR-124a and the Sox17/Gata6 transcription factors in hepato-specific gene regulation. In addition, we presented a feasible in vivo system that utilizes teratoma and gene expression profiling from microarray to quantitatively evaluate the functional role of miRNA in lineage specification. We demonstrated that ectopic expression of miR-124a in teratomas by intratumor delivery of miR-124a mimic and Atelocollagen, significantly suppressed endoderm and mesoderm lineage differentiation while augmenting the differentiation into ectoderm lineage. Collectively, our findings suggest that miR-124a plays a significant role in mESCs lineage commitment.
  6. Ko CCH, Chia WK, Selvarajah GT, Cheah YK, Wong YP, Tan GC
    Diagnostics (Basel), 2020 Sep 19;10(9).
    PMID: 32961774 DOI: 10.3390/diagnostics10090721
    Breast cancer is one of the leading causes of cancer-related deaths in women worldwide, and its incidence is on the rise. A small fraction of cancer stem cells was identified within the tumour bulk, which are regarded as cancer-initiating cells, possess self-renewal and propagation potential, and a key driver for tumour heterogeneity and disease progression. Cancer heterogeneity reduces the overall efficacy of chemotherapy and contributes to treatment failure and relapse. The cell-surface and subcellular biomarkers related to breast cancer stem cell (BCSC) phenotypes are increasingly being recognised. These biomarkers are useful for the isolation of BCSCs and can serve as potential therapeutic targets and prognostic tools to monitor treatment responses. Recently, the role of noncoding microRNAs (miRNAs) has extensively been explored as novel biomarker molecules for breast cancer diagnosis and prognosis with high specificity and sensitivity. An in-depth understanding of the biological roles of miRNA in breast carcinogenesis provides insights into the pathways of cancer development and its utility for disease prognostication. This review gives an overview of stem cells, highlights the biomarkers expressed in BCSCs and describes their potential role as prognostic indicators.
  7. Fatimah SS, Tan GC, Chua K, Fariha MM, Tan AE, Hayati AR
    Microvasc Res, 2013 Mar;86:21-9.
    PMID: 23261754 DOI: 10.1016/j.mvr.2012.12.004
    Particular attention has been directed towards human amnion mesenchymal stem cells (HAMCs) due to their accessibility, availability and immunomodulatory properties. Therefore, the aim of the present study was to determine the temporal changes of stemness and angiogenic gene expressions of serial-passage HAMCs.
  8. Cheah FC, Lai CH, Tan GC, Swaminathan A, Wong KK, Wong YP, et al.
    Front Pediatr, 2020;8:593802.
    PMID: 33553066 DOI: 10.3389/fped.2020.593802
    Background:Gardnerella vaginalis (GV) is most frequently associated with bacterial vaginosis and is the second most common etiology causing intrauterine infection after Ureaplasma urealyticum. Intrauterine GV infection adversely affects pregnancy outcomes, resulting in preterm birth, fetal growth restriction, and neonatal pneumonia. The knowledge of how GV exerts its effects is limited. We developed an in vivo animal model to study its effects on fetal development. Materials and Methods: A survival mini-laparotomy was conducted on New Zealand rabbits on gestational day 21 (28 weeks of human pregnancy). In each dam, fetuses in the right uterine horn received intra-amniotic 0.5 × 102 colony-forming units of GV injections each, while their littermate controls in the left horn received sterile saline injections. A second laparotomy was performed seven days later. Assessment of the fetal pups, histopathology of the placenta and histomorphometric examination of the fetal lung tissues was done. Results: Three dams with a combined total of 12 fetuses were exposed to intra-amniotic GV, and 9 fetuses were unexposed. The weights of fetuses, placenta, and fetal lung were significantly lower in the GV group than the saline-inoculated control group [mean gross weight, GV (19.8 ± 3.8 g) vs. control (27.9 ± 1.7 g), p < 0.001; mean placenta weight, GV (5.5 ± 1.0 g) vs. control (6.5 ± 0.7 g), p = 0.027; mean fetal lung weight, GV (0.59 ± 0.11 g) vs. control (0.91 ± 0.08 g), p = 0.002. There was a two-fold increase in the multinucleated syncytiotrophoblasts in the placenta of the GV group than their littermate controls (82.9 ± 14.9 vs. 41.6 ± 13.4, p < 0.001). The mean alveolar septae of GV fetuses was significantly thicker than the control (14.8 ± 2.8 μm vs. 12.4 ± 3.8 μm, p = 0.007). Correspondingly, the proliferative index in the interalveolar septum was 1.8-fold higher in the GV group than controls (24.9 ± 6.6% vs. 14.2 ± 2.9%, p = 0.011). The number of alveoli and alveolar surface area did not vary between groups. Discussion: Low-dose intra-amniotic GV injection induces fetal growth restriction, increased placental multinucleated syncytiotrophoblasts and fetal lung re-modeling characterized by alveolar septal hypertrophy with cellular proliferative changes. Conclusion: This intra-amniotic model could be utilized in future studies to elucidate the acute and chronic effects of GV intrauterine infections.
  9. Tan GC, Shiran MS, Hayati AR, Sharifah NA, Nuru AS, Rohaizak M
    J Chin Med Assoc, 2008 Dec;71(12):639-42.
    PMID: 19114329
    Rhabdomyosarcoma is a common extramammary malignancy in pediatric age groups, but it rarely metastasizes to the breast. Breast rhabdomyosarcomas are commonly metastatic, with possible primary locations at the head and neck, trunk, extremities, retroperitoneum and perianal region. We report a case of primary alveolar rhabdomyosarcoma of the upper extremities in a 17-year-old adolescent female who presented with bilateral lower limb weakness and bilateral breast lumps.
  10. Wong YP, Sharifah NA, Tan GC, Gill AJ, Ali SZ
    Diagn Cytopathol, 2016 May 26.
    PMID: 27229757 DOI: 10.1002/dc.23493
    Oxyphilic (oncocytic) parathyroid lesions are very uncommon and their cytological features are rarely described. Due to the similarities in anatomical location and indistinguishable cytomorphological features, these lesions are easily confused with neoplastic and non-neoplastic thyroid lesions on fine needle aspiration (FNA). The diagnosis becomes more challenging in cases of unusual intrathyroidal location of the parathyroid lesions in the absence of clinical evidence of hyperparathyroidism, which simulate thyroid nodules clinically. We describe a case of intrathyroidal oxyphilic parathyroid carcinoma in a 66-year-old female, who presented with a dominant left "thyroid" nodule. FNA smears were cellular, comprising predominantly of oxyphilic cells arranged in papillary-like architecture with occasional nuclear grooves, which was mistaken for oncocytic variant of papillary carcinoma of the thyroid. The histological diagnosis of oxyphilic parathyroid "adenoma" was made following total thyroidectomy. The tumor, unfortunately, recurred 7 years later with associated multiple lung metastases. When dealing with thyroid lesions comprising predominantly of oncocytic cells, one should consider oxyphilic parathyroid neoplasms as one of the differential diagnosis. In difficult equivocal cases, a panel of immunocytochemical stains (PTH, GATA3, TTF-1, PAX8, and thyroglobulin) can be helpful. In addition, a combination of valuable clinical, radiological, and laboratory data, including serum calcium and parathyroid hormone levels are key to arriving at an accurate cytological diagnosis. Diagn. Cytopathol. 2016. © 2016 Wiley Periodicals, Inc.
  11. Nur Fariha MM, Chua KH, Tan GC, Lim YH, Hayati AR
    Cell Biol Int, 2012;36(12):1145-53.
    PMID: 22957758 DOI: 10.1042/CBI20120044
    Cell-based therapy using stem cells has emerged as one of the pro-angiogenic methods to enhance blood vessel growth and sprouting in ischaemic conditions. This study investigated the endogenous and induced angiogenic characteristics of hCDSC (human chorion-derived stem cell) using QPCR (quantitative PCR) method, immunocytochemistry and fibrin-matrigel migration assay. The results showed that cultured hCDSC endogenously expressed angiogenic-endogenic-associated genes (VEGF, bFGF, PGF, HGF, Ang-1, PECAM-1, eNOS, Ve-cad, CD34, VEGFR-2 and vWF), with significant increase in mRNA levels of PGF, HGF, Ang-1, eNOS, VEGFR-2 and vWF following induction by bFGF (basic fibroblast growth factor) and VEGF (vascular endothelial growth factor). These enhanced angiogenic properties suggest that induced hCDSC provides a stronger angiogenic effect for the treatment of ischaemia. After angiogenic induction, hCDSC showed no reduction in the expression of the stemness genes, but had significantly higher levels of mRNA of Oct-4, Nanog (3), FZD9, ABCG-2 and BST-1. The induced cells were positive for PECAM-1 (platelet/endothelial cell adhesion molecule 1) and vWF (von Willebrand factor) with immunocytochemistry staining. hCDSC also showed endothelial migration behaviour when cultured in fibrin-matrigel construct and were capable of forming vessels in vivo after implanting into nude mice. These data suggest that hCDSC could be the cells of choice in the cell-based therapy for pro-angiogenic purpose.
  12. Wong YP, Yahaya A, Che Abdul Aziz R, Chia PY, Loh CK, Tan GC
    Malays J Pathol, 2020 Aug;42(2):301-305.
    PMID: 32860387
    INTRODUCTION: Yolk sac tumour (YST) or endodermal sinus tumour is rare and typically seen in gonads.

    CASE REPORT: We described a case of extragonadal vaginal YST in a one year and seven months old girl who presented with vaginal discharge and bleeding, and discuss its differential diagnosis and potential pitfalls in immunohistochemistry. She was found to have a suprapubic mass on examination. The serum alpha fetoprotein was 11919.4 ng/mL. Computed tomography of the pelvis revealed a large 6.4 cm heterogenous pelvic mass. Colposcopic examination of the pelvis showed a fungating vaginal mass that was subsequently confirmed as a yolk sac tumour. Immunohistochemically, the malignant cells were positive toward CKAE1/AE3, AFP and glypican-3, as well as CD117.

    DISCUSSION: Solid pattern extragonadal vaginal YST may morphologically resemble dysgerminoma that is also CD117 positive, while the glandular pattern YST may have clear cytoplasm and is positive for cytokeratin; hence, may resemble clear cell carcinoma. Being mindful of these potential diagnostic caveats is necessary to prevent misdiagnosis.

  13. Tan GC, Stalling M, Al-Rawabdeh S, Kahwash BM, Alkhoury RF, Kahwash SB
    Malays J Pathol, 2018 Apr;40(1):11-26.
    PMID: 29704380
    Tonsillectomy is among the most commonly performed operations in children. Although follicular lymphoid hyperplasia is usually the main and only pathologic finding at microscopic examination, a variety of other rare but important pathologic changes may be encountered. This review aims to provide an inclusive practical resource and reference for both training and practising pathologists. It discusses the spectrum of pathologic findings, including both neoplastic and non-neoplastic conditions and provides illustrative images.
  14. Mohammed F, Tan GC, Hor KN, Arnold M, Wong YP
    Cardiovasc. Pathol., 2020 05 12;49:107226.
    PMID: 32574866 DOI: 10.1016/j.carpath.2020.107226
    Cardiac rhabdomyoma is the most prevalent cardiac tumors in the pediatric population, in close association with tuberous sclerosis complex. It is usually detected antenatally or postnatally by echocardiography. Clinical presentations depend greatly on the size and position of the tumor mass. Interestingly, rhabdomyoma has a propensity to regress spontaneously and is not usually operated upon, unless the patient becomes hemodynamically compromised. Herein, we report an unusual case of surgically treated cardiac rhabdomyoma in a baby boy presented at birth with a progressive enlarging intraventricular mass, complicated with left ventricular outflow tract obstruction 7 weeks later. Histopathological examination of the intracardiac mass revealed sheets of tumor cells with spider-like morphology (known as "spider cells"), confirmed the diagnosis of rhabdomyoma. Close disease monitoring of patient's hemodynamic status in a newly diagnosed cardiac rhabdomyoma is inevitable as the tumor, although rare, may progress.
  15. Tan LJ, Tan GC, Hussin H, Othman MS, Lai SK
    PMID: 34687904 DOI: 10.1016/j.jpag.2021.10.002
    BACKGROUND: Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a congenital disorder characterized by underdevelopment of the uterus and vagina.

    CASE: A 4-year-old girl was declared dead on arrival to the hospital with a history of chronic constipation since birth. Postmortem examination showed Müllerian remnants attached to abnormal fibrous tissue. The fibrous tissue extended from the descending colon to the rectum and connected to a urinary bladder duplication cyst. The fibrous tissue formed into a constricted band around the rectum. The cause of death was Streptococcus pyogenes sepsis with intestinal obstruction secondary to the rectal fibrotic band and urinary bladder duplication cyst.

    SUMMARY AND CONCLUSION: MRKH syndrome is a rare congenital disorder, and the malformations rarely cause death. We describe the features of abnormal fibrous tissue and urinary bladder duplication cyst in a patient with MRKH syndrome.

  16. Wong YP, Chia WK, Selimin A, Chia PY, Mustangin M, Shuib S, et al.
    Malays J Pathol, 2021 Dec;43(3):341-351.
    PMID: 34958055
    INTRODUCTION: Hydatidiform moles (HMs) include complete and partial moles, are the result of abnormal fertilisation. The accurate classification of HMs and its distinction from non-molar specimens is utmost important for clinical management and risk assessment. It is diagnostically challenging if the distinction is based solely on histomorphology with poor interobserver reproducibility, especially in early gestations. This study aimed to investigate the diagnostic ability of combined p57 immunohistochemistry and DNA ploidy analysis to distinguish between complete moles, partial moles and non-molar abortus.

    MATERIALS AND METHODS: We included all HMs cases diagnosed in our centre over a six-year period. p57 immunohistochemistry stain was performed. Only nuclear immunoreactivity in >50% of cytotrophoblasts and villous stromal cells was regarded as positive for p57. DNA ploidy status was determined by fluorescence in situ hybridisation. A total of 250 cells from five chorionic villi were counted and were scored as diploid or triploid if more than 10% of nuclei demonstrated two or three signals, respectively.

    RESULTS: A total of 51 cases originally diagnosed by histomorphology as complete mole (n = 18), partial mole (n = 24) and non-molar abortus (n = 9) were recruited. The cases were reclassified based on the p57 immunostaining pattern and DNA ploidy status, into 27 complete moles (p57-/diploid), 9 partial moles (p57+/triploid) and 15 non-molar abortus (p57+/diploid). The diagnostic accuracy by histomorphological features alone in each category: complete moles, partial moles and non-molar abortus was 78.4%, 70.6% and 88.2% respectively.

    CONCLUSION: This study highlighted the importance of the utility of combined p57 immunostain and DNA ploidy analysis in arriving at an accurate diagnosis in HMs. An algorithmic approach utilising these ancillary techniques is advocated in routine diagnostic workup for a more refined diagnostic approach to HMs.

  17. Arshad M, Abdul Hamid N, Chan MC, Ismail F, Tan GC, Pezzella F, et al.
    Cells, 2021 08 24;10(9).
    PMID: 34571823 DOI: 10.3390/cells10092176
    Cancer increases the global disease burden substantially, but it remains a challenge to manage it. The search for novel biomarkers is essential for risk assessment, diagnosis, prognosis, prediction of treatment response, and cancer monitoring. This paper examined NEDD8 ultimate buster-1 (NUB1) and F-adjacent transcript 10 (FAT10) proteins as novel biomarkers in cancer. This literature review is based on the search of the electronic database, PubMed. NUB1 is an interferon-inducible protein that mediates apoptotic and anti-proliferative actions in cancer, while FAT10 is a ubiquitin-like modifier that promotes cancer. The upregulated expression of both NUB1 and FAT10 has been observed in various cancers. NUB1 protein binds to FAT10 non-covalently to promote FAT10 degradation. An overexpressed FAT10 stimulates nuclear factor-kappa β, activates the inflammatory pathways, and induces the proliferation of cancer. The FAT10 protein interacts with the mitotic arrest deficient 2 protein, causing chromosomal instability and breast tumourigenesis. FAT10 binds to the proliferating cell nuclear antigen protein and inhibits the DNA damage repair response. In addition, FAT10 involves epithelial-mesenchymal transition, invasion, apoptosis, and multiplication in hepatocellular carcinoma. Our knowledge about them is still limited. There is a need to further develop NUB1 and FAT10 as novel biomarkers.
  18. Sahabi K, Selvarajah GT, Abdullah R, Cheah YK, Tan GC
    J Vet Sci, 2018 Mar 31;19(2):162-171.
    PMID: 28927253 DOI: 10.4142/jvs.2018.19.2.162
    MicroRNAs (miRNAs) have important roles in all biological pathways in multicellular organisms. Over 1,400 human miRNAs have been identified, and many are conserved among vertebrates and invertebrates. Regulation of miRNA is the most common mode of post-transcriptional gene regulation. The miRNAs that are involved in the initiation and progression of cancers are termed oncomiRs and several of them have been identified in canine and human cancers. Similarly, several miRNAs have been reported to be down-regulated in cancers of the two species. In this review, current information on the expression and roles of miRNAs in oncogenesis and progression of human and canine cancers, as well the roles miRNAs have in cancer stem cell biology, are highlighted. The potential for the use of miRNAs as therapeutic targets in personalized cancer therapy in domestic dogs and their possible application in human cancer counterparts are also discussed.
  19. Sheshala R, Quah SY, Tan GC, Meka VS, Jnanendrappa N, Sahu PS
    Drug Deliv Transl Res, 2019 04;9(2):434-443.
    PMID: 29392681 DOI: 10.1007/s13346-018-0488-6
    The objectives of present research were to develop and characterize thermosensitive and mucoadhesive polymer-based sustained release moxifloxacin in situ gels for the treatment of periodontal diseases. Poloxamer- and chitosan-based in situ gels are in liquid form at room temperature and transform into gel once administered into periodontal pocket due to raise in temperature to 37 °C. Besides solution-to-gel characteristic of polymers, their mucoadhesive nature aids the gel to adhere to mucosa in periodontal pocket for prolonged time and releases the drug in sustained manner. These formulations were prepared using cold method and evaluated for pH, solution-gel temperature, syringeability and viscosity. In vitro drug release studies were conducted using dialysis membrane at 37 °C and 50 rpm. Antimicrobial studies carried out against Aggregatibacter actinomycetemcomitans (A.A.) and Streptococcus mutans (S. Mutans) using agar cup-plate method. The prepared formulations were clear and pH was at 7.01-7.40. The viscosity of formulations was found to be satisfactory. Among the all, formulations comprising of 21% poloxamer 407 and 2% poloxamer 188 (P5) and in combination with 0.5% HPMC (P6) as well as 2% chitosan and 70% β-glycerophosphate (C6) demonstrated an ideal gelation temperature (33-37 °C) and sustained the drug release for 8 h. Formulations P6 and C6 showed promising antimicrobial efficacy with zone of inhibition of 27 mm for A.A. and 55 mm for S. Mutans. The developed sustained release in situ gel formulations could enhance patient's compliance by reducing the dosing frequency and also act as an alternative treatment to curb periodontitis.
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