Displaying publications 1 - 20 of 106 in total

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  1. Dasrilsyah RA, Ahmad S, Tan GC, Lim PS
    MyJurnal
    Congenital leukemia is an extremely rare disease but frequently fatal. We report a case of intrauterine death (IUD) secondary to congenital erythroid leukaemia associated with maternal Parvovirus B19 infection. Further research is needed to ascertain the association between maternal Parvovirus B19 infection and congenital leukemia.
  2. Tan GC, Dibb N
    Malays J Pathol, 2015 Aug;37(2):73-81.
    PMID: 26277662 MyJurnal
    Since the inception of deep sequencing, isomiRs are consistently observed to be produced by most miRNA genes in a variety of cell types. IsomiRs appear as a variation in length from the canonical sequence annotated in miRBase, due to an addition or deletion of one or more nucleotides at the 5(') or 3(') ends or both. As the seed sequence is located at the 5(') end of the microRNA, the target mRNA will be theoretically different. Therefore, 5(')isomiRs might potentially target a new set mRNA compared to their canonical counterpart. This article gives an overview of investigations that explored the functional potential of isomiRs such as their ability to incorporate into Argonaute protein, the differential expression of isomiRs in various tissue types and cell lines, and the differences of mRNA targets between isomiR and its canonical microRNA. In addition, this article provides a brief introduction of RNA sponges as a potential way to inhibit isomiRs.
  3. Tan, GC, Sharifah, N.A., Salwati, S., Hatta, A.Z., Shiran, M.S, Ng, Ho
    Medicine & Health, 2007;2(2):125-132.
    MyJurnal
    One of the most important cervical cancer risk factors is human papillomavirus (HPV) infection. The p53 gene is one of the most important targets of the HPV E6 gene. E6 protein has the ability to stimulate p53 degradation, inhibits several functions of wild-type p53 and it competes with its function including suppression of malignant growth. The aim of this study is to determine the differences in p53 expressions in pre-malignant and malignant cervical neoplasms. This is a retrospective study on 100 cases of cervical neoplasms. There were 21 cases of CIN 1, 8 cases of CIN 2, 25 cases of CIN 3, 36 cases of squamous cell carcinoma, 7 cases of adenocarcinoma and 3 cases of adenosquamouscarcinoma. All cases were evaluated by immunohistochemistry using p53 monoclonalantibody. Thirty six of the 54 pre-malignant cases (66.7%) were positive for p53 protein, n contrast to the malignant cases in which, 40 of the 46 cases (87.0%) were positive. he majority of CIN showed absent to focal staining (29/54, 53.7%). In contrast, 84.8% (39/46( of the invasive carcinoma showed regional to diffuse staining. The expression of p53 is greater in the malignant cervical neoplasms than the pre-malignant cervical lesions, suggesting that p53 overexpression is not an early phenomenon in the pathogenesis of cervical cancer. It is also shown to be slightly higher in percentage in CIN 2 and 3 when compared with CIN 1. However, a number of cases were p53 negative, suggesting that other factors may be involved and further HPV studies are indicated.
  4. Wong YP, Tan GC
    Malays J Pathol, 2021 Apr;43(1):1.
    PMID: 33903298
    No abstract available.
  5. Naicker MS, Tan GC
    Malays J Pathol, 2018 Dec;40(3):319-323.
    PMID: 30580363
    INTRODUCTION: Clinical decision making becomes difficult when clinical and methodological heterogeneity does not permit synthesis of results of multiple small studies.

    AIM: For studies done in Malaysia, to identity the sample sizes and heterogeneity present in the various studies which used p16 in evaluating lesions of the cervix. To evaluate if it would be possible for a single study to answer the various questions posed by the original authors. To highlight areas where the design features of future studies can be optimised.

    MATERIALS AND METHODS: Various databases were searched using synonyms for p16 AND cervix AND Malaysia. These were assessed for broad conformity to a Diagnostic Test Accuracy format. Methodological and clinical heterogeneity indicators were extracted into standardised fields.

    RESULTS: There were 5 studies eligible for inclusion. Each sought to study different aspects of the disease such as diagnostic grade stratification and pathogenesis. The study type broadly conformed to a Diagnostic Test Accuracy format. The study design used was either consecutive or non-consecutive. Sample size ranged from 75 to 201. Clinical heterogeneity was present in the choice of controls with some using normal and some using inflamed tissue. Methodological heterogeneity in applying the reference test, index test and different antibody clones were present.

    CONCLUSION: There was both clinical and methodological heterogeneity making synthesis of studies difficult. It is possible to design a study which would be able to answer all the questions posed by the original authors with internal validity while at the same time increasing sample size.

  6. Tan GC, Cheong SK
    Malays J Pathol, 2020 Apr;42(1):1.
    PMID: 32342925
    No abstract available.
  7. Tan GC, Wong YP
    Malays J Pathol, 2021 Dec;43(3):339.
    PMID: 34958054
    No abstract available.
  8. Tan GC, Wong YP
    Malays J Pathol, 2021 Aug;43(2):201.
    PMID: 34448785
    No abstract available.
  9. Tan GC, Wong YP
    Malays J Pathol, 2022 Dec;44(3):365.
    PMID: 36591706
    No abstract available.
  10. Tan GC, Cheong SK
    Malays J Pathol, 2023 Dec;45(3):315.
    PMID: 38155374
    No abstract available.
  11. Hayati AR, Mohamed AE, Tan GC
    Malays J Pathol, 2010 Jun;32(1):13-9.
    PMID: 20614721 MyJurnal
    The placenta constitutes a physical and immunological barrier against infectious agents. Toll-like receptors (TLRs) are essential components for the induction of innate immunity responses in different human tissues including the placenta. We investigated the expressions of TLR2 and TLR4 in the decidua and amniotic cells in non-inflamed placenta and placenta with infection.
  12. Wong YP, Tan GC, Kumar R
    Neuropathology, 2018 Dec;38(6):619-623.
    PMID: 30187570 DOI: 10.1111/neup.12511
    Xanthomatous changes can be observed in various conditions including primary xanthomatosis that is linked to an underlying hypercholesterolemia and more commonly associated with secondary xanthomatous degenerative processes in neoplasm and chronic inflammation. Meningioma with extensive xanthomatous change is exceedingly rare. The presence of cholesterol clefts within this peculiar meningioma subtype has not been described. Herein, we report an unusual case of xanthomatous meningioma in an 83-year-old normolipidemic woman, who presented to us with worsening lower limb weakness and global aphasia. There was increasing evidence to suggest that the presence of xanthomatous changes in long-standing meningioma is merely a sequela of cellular degeneration rather than true metaplastic change as previously hypothesized. Hence, the diagnosis of "xanthomatous meningioma" in the metaplastic category should be revisited and considered as a distinct histological subtype. The possible histogenesis of such intriguing phenomenon is discussed with a review of the literature.
  13. Wong YP, Tan GC, Muhammad R, Rajadurai P
    Malays J Pathol, 2020 Apr;42(1):151-155.
    PMID: 32342946
    INTRODUCTION: Occult primary breast carcinoma (OBC) manifesting as axillary nodal metastasis without an identifiable breast primary is exceptionally rare. It continues to pose a diagnostic challenge to pathologists. Here, we report a case of OBC with emphasis on the usefulness of immunohistochemistry to determine the primary site of tumour.

    CASE REPORT: A 58-year-old female presented with a 3-cm painless right axillary mass. Extensive radiological investigations that include mammography, ultrasonography of the breasts and positron emission tomography (PET) scan failed to conclude the primary site of the tumour. Histological examination of the lymph node revealed loosely cohesive sheets of poorly differentiated malignant cells, without discernible glandular or squamous differentiation. Immunohistochemically, the malignant cells exhibited diffuse immunoreactivity toward pan-cytokeratin and CK7, while leukocyte common antigen, S100 and CK20 were negative. A second panel of immunomarkers was carried out. The malignant cells expressed breast-specific markers (GATA-3, GCDFP-15 and mammaglobin), and were negative for ER, PR and TTF-1 immunohistochemistry. A diagnosis of OBC was rendered.

    DISCUSSION: Breast primary must always be considered in the differential diagnosis in patients with sole presentation of axillary lymphadenopathy. The breast-specific immunomarkers play a pivotal role in the diagnosis of ER, PR-negative occult breast cancer.

  14. Tan GC, Wong YP, Cui W, Dibb N
    Malays J Pathol, 2020 Apr;42(1):91-97.
    PMID: 32342936
    INTRODUCTION: The polycistronic miR-302 cluster encodes five miRNA genes that have an important role in the regulation of embryonic stem cell function. Studies showed that the miR-302 cluster can reprogram both mouse and human fibroblasts to induced pluripotent stem cells (iPSCs) with high efficiency. The aim of this study was to generate an inducible lentivirus that expresses miR-302 cluster in order to further investigate somatic cell reprogramming by these miRNAs.

    MATERIALS AND METHODS: The miR-302 cluster was amplified by polymerase chain reaction technique from human genomic DNA and was ligated into pTRIPz, an inducible lentiviral vector.

    RESULTS: MRC5 fibroblasts and HEK293 (human embryonic kidney) cells were infected with pTRIPz-302 cluster lentivirus and the family of 302 miRNAs were strongly expressed in HEK293 cells but lowly expressed in MRC5 fibroblasts. When cultured in hESC conditions, MRC5 cells expressed only low levels of DNMT3B, Nanog, Oct4 and Lin28 and failed to show stem cell induction. The red fluorescent expression seen in the majority of MRC5 cells, indicated that the rate of infection by lentivirus was efficient.

    DISCUSSION: The efficiency of reprogramming may be improved perhaps by either using a different cell type or a high expression vector with a different type of promoter.

  15. Wong YP, Tan GC, Khong TY
    Int J Mol Sci, 2023 Feb 25;24(5).
    PMID: 36901979 DOI: 10.3390/ijms24054550
    The outbreak of the coronavirus disease 2019 (COVID-19) pandemic, caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global public health crisis, causing substantial concern especially to the pregnant population. Pregnant women infected with SARS-CoV-2 are at greater risk of devastating pregnancy complications such as premature delivery and stillbirth. Irrespective of the emerging reported cases of neonatal COVID-19, reassuringly, confirmatory evidence of vertical transmission is still lacking. The protective role of the placenta in limiting in utero spread of virus to the developing fetus is intriguing. The short- and long-term impact of maternal COVID-19 infection in the newborn remains an unresolved question. In this review, we explore the recent evidence of SARS-CoV-2 vertical transmission, cell-entry pathways, placental responses towards SARS-CoV-2 infection, and its potential effects on the offspring. We further discuss how the placenta serves as a defensive front against SARS-CoV-2 by exerting various cellular and molecular defense pathways. A better understanding of the placental barrier, immune defense, and modulation strategies involved in restricting transplacental transmission may provide valuable insights for future development of antiviral and immunomodulatory therapies to improve pregnancy outcomes.
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