Displaying publications 41 - 60 of 68 in total

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  1. Teoh HK, Chong PP, Abdullah M, Sekawi Z, Tan GC, Leong CF, et al.
    Leuk. Res., 2016 Jan;40:44-53.
    PMID: 26626206 DOI: 10.1016/j.leukres.2015.10.004
    Studies demonstrated that mesenchymal stromal cells (MSC) from bone marrow stroma produced high concentration of interleukin-6 (IL-6) that promoted multiple myeloma cell growth. In view of the failure of IL-6 monoclonal antibody therapy to demonstrate substantial clinical responses in early clinical trials, more effective methods are needed in order to disrupt the favourable microenvironment provided by the bone marrow stroma. In this study, we evaluated the short interfering RNA (siRNA)-mediated silencing of IL-6 in MSC and the efficacy of these genetically modified MSC, with IL-6 suppression, on inhibition of U266 multiple myeloma cell growth. IL-6 mRNA and protein were significantly suppressed by 72h post IL-6 siRNA transfection without affecting the biological properties of MSC. Here we show significant inhibition of cell growth and IL-6 production in U266 cells co-cultured with MSC transfected with IL-6 siRNA when compared to U266 cells co-cultured with control MSC. We also show that the tumour volume and mitotic index of tumours in nude mice co-injected with U266 and MSC transfected with IL-6 siRNA were significantly reduced compared to tumours of mice co-injected with control MSC. Our results suggest potential use of RNA interference mediated therapy for multiple myeloma.
  2. Nurasyikin Y, Leong CF, Fadhlullah TM, Hafiz WM, Nadiah Z, Atieqah AN, et al.
    Clin Ter, 2011;162(1):19-22.
    PMID: 21448541
    The main objective of the present study was to evaluate the temperature chain of red blood cells (RBC) returned unused blood bags using blood temperature indicator and ascertain the factors like transportation time, type, size of coolant box and number of bags per box.
  3. Wong FL, Hamidah NH, Hawa AA, Nurul AN, Leong CF, Saw F, et al.
    Malays J Pathol, 2011 Dec;33(2):107-12.
    PMID: 22299211
    Molecular pathogenesis of chronic myeloid leukemia (CML) is well established and molecular monitoring for patients with CML has become an important practice in the management of patients on imatinib therapy. In the present study, we report the use of RQ-PCR method for detection of BCR-ABL fusion gene for our CML cases. We performed a two-step RQ-PCR on bone marrow aspirates or peripheral blood of 37 CML patients. Quantitative expression of BCR-ABL fusion gene was carried out relative to the expression of a housekeeping gene as endogenous control to compensate for uneven cell numbers, RNA quality, or variations in reverse transcription efficiencies. Twenty-four of these patients were pre-treated with hydroxyurea or alpha interferon prior to the imatinib therapy. Their BCR-ABL fusion gene levels were monitored for 18 months. All samples processed were evaluable. The PCR amplification efficiency of the ABL gene is 90.5% (0.2158) and the BCR-ABL gene, 93.4% (0.1573).
  4. Tan YF, Sim GC, Habsah A, Leong CF, Cheong SK
    Malays J Pathol, 2008 Dec;30(2):73-9.
    PMID: 19291915 MyJurnal
    Dendritic cells (DC) are professional antigen presenting cells of the immune system. Through the use of DC vaccines (DC after exposure to tumour antigens), cryopreserved in single-use aliquots, an attractive and novel immunotherapeutic strategy is available as an option for treatment. In this paper we describe an in vitro attempt to scale-up production of clinical-grade DC vaccines from leukemic cells. Blast cells of two relapsed AML patients were harvested for DC generation in serum-free culture medium containing clinical-grade cytokines GM-CSF, IL-4 and TNF-alpha. Cells from patient 1 were cultured in a bag and those from patient 2 were cultured in a flask. The numbers of seeding cells were 2.24 x 10(8) and 0.8 x 10(8), respectively. DC yields were 10 x 10(6) and 29.8 x 10(6) cells, giving a conversion rate of 4.7% and 37%, respectively. These DC vaccines were then cryopreserved in approximately one million cells per vial with 20% fresh frozen group AB plasma and 10% DMSO. At 12 months and 21 months post cryopreservation, these DC vaccines were thawed, and their sterility, viability, phenotype and functionality were studied. DC vaccines remained sterile up to 21 months of storage. Viability of the cryopreserved DC in the culture bag and flask was found to be 50% and 70% at 12 months post cryopreservation respectively; and 48% and 67% at 21 months post cryopreservation respectively. These DC vaccines exhibited mature DC surface phenotypic markers of CD83, CD86 and HLA-DR, and negative for haemopoietic markers. Mixed lymphocyte reaction (MLR) study showed functional DC vaccines. These experiments demonstrated that it is possible to produce clinical-grade DC vaccines in vitro from blast cells of leukemic patients, which could be cryopreserved up to 21 months for use if repeated vaccinations are required in the course of therapy.
  5. Leong CF, Habsah A, Teh HS, Goh KY, Fadilah SA, Cheong SK
    Malays J Pathol, 2008 Jun;30(1):31-6.
    PMID: 19108409
    Peripheral blood stem cells (PBSC) mobilised with growth factor with or without chemotherapeutic regimens, are used increasingly in both autologous and allogeneic transplantation. Previously, many PBSC harvests are used directly without ex vivo manipulation, and these PBSC have been shown to be contaminated with tumour cells, which may contribute to subsequent relapses post transplantation. Therefore, requirement for purging of malignant cells from the harvest has initiated the use of various methods to reduce tumour cell contamination of the graft by the positive selection of CD34+ progenitor cells or negative selection of tumour cells using other cell-specific antigens. We report here our local experience with the CliniMACS (magnetic-activated cell separation system) in eight adult patients with haematologic malignancies.
  6. Fadilah SA, Leong CF, Jamil MY, Cheong SK, Rozilaila R
    Med J Malaysia, 2006 Aug;61(3):358-60.
    PMID: 17240590 MyJurnal
    Hodgkin's disease (HD) in association with pregnancy is rarely reported. Thus, the data in the management of pregnancy complicated by HD is limited. We report here the management of advanced HD in pregnancy that was treated successfully with chemotherapy.
  7. Choong PF, Mok PL, Cheong SK, Leong CF, Then KY
    Cytotherapy, 2007;9(2):170-83.
    PMID: 17453969
    The multipotency of stromal cells has been studied extensively. It has been reported that mesenchymal stromal cells (MSC) are capable of differentiating into cells of multilineage. Different methods and reagents have been used to induce the differentiation of MSC. We investigated the efficacy of different growth factors in inducing MSC differentiation into neurons.
  8. Gan GG, Leong CF, Sangkar JV, Teh A, Goh KY, Cheong SK
    Med J Malaysia, 2005 Aug;60(3):311-3.
    PMID: 16379185
    Aplastic anemia is a relatively uncommon disease and conventional management options include immunosuppressive drugs and/or haematopoeitic stem cell transplantation. It is now known that the pathogenesis of aplastic anemia is immune mediated. Mycophenolate mofetil is a common immunosuppressive drug now used mainly in prophylaxis of graft rejection in organ transplant and also for prevention/treatment for graft versus host disease in haemtopoeitic stem cell transplantation. It is thought that mycophenolate mofetil may be useful in this group of patients. In this short report, mycophenolate mofetil was tried in 6 patients who had severe aplastic anemia with variable doses for a minimum duration of 9 months. The result has however not been encouraging.
  9. Leong CF, Kalaichelvi AV, Cheong SK, Hamidah NH, Rahman J, Sivagengei K
    Malays J Pathol, 2004 Dec;26(2):111-6.
    PMID: 16329563
    Myeloperoxidase (MPO) is present in azurophilic granules which appear in the promyelocyte stage of differentiation and is expressed in granulomonocytic cells. MPO is usually detected by cytochemistry. The demonstration of peroxidase in at least 3% of bone marrow blasts defines an acute leukaemia as acute myeloblastic leukaemia (AML). MPO is important in distinguishing acute myeloblastic leukaemia (AML) from acute lymphoblastic leukaemia (ALL). It is difficult to diagnose AML with minimal evidence of myeloid differentiation (AML- M0) by conventional light microscopy. However, these AML-M0 blasts can be detected by monoclonal antibodies. Anti-MPO recognizes the enzymatically inactive precursor forms of MPO. There are a few commercially available monoclonal antibodies against MPO. In this study, we evaluated two monoclonal antibodies against MPO from different commercial sources.
  10. Syed Azim SM, Muhamad NA, Leong CF, Hussin NH
    Malays J Pathol, 2015 Aug;37(2):109-14.
    PMID: 26277667 MyJurnal
    Antibody screening is important for the antenatal screening and pre-transfusion tests. This study aimed to compare the MUT/Mur kodecytesAbtectcell III (CSL Abtectcell III) red cell antibody screening kit with DiaMed ID-Dia Cell I-II-III Asia that was then used in our laboratory. In this study, 125 samples were randomly chosen, with 67 samples of known antibody specificities and 58 samples identified as negative for antibody, as the negative control. Concordant negative results were obtained in 57 out of 58 antibody negative samples. Concordant antibody positive results with both reagents were seen in 49 out of 67 samples. There were 18 discrepant results of antibody screening with CSL Abtetcell III (16/18 for vMNS antibodies). The sensitivity and specificity for CSL Abtectcell III were 73.0% and 98.3% respectively. In conclusion, the CSL Abtectcell III reagent would be an acceptable alternative for screening of red cell alloantibodies. It was able to detect all the clinically significant alloantibodies.
  11. Leong CF, Cheong SK, Fadilah SAW, Ainoon O, Hamidah NH
    Med J Malaysia, 2003 Jun;58(2):229-35.
    PMID: 14569743
    Allogeneic haemopoietic stem cell transplantation was initially considered as a means of delivering supralethal doses of chemotherapy with or without total body irradiation for the treatment of malignancy. However, it has become clear that this mode of therapy does not eradicate the malignancy in many patients and its benefit is largely due to the immune mediated graft versus malignancy effect. This has led to development of alternative strategy to utilize a less intensive preparative regimen pre-transplantation that provides sufficient immunosuppression to achieve engraftment of an allogeneic stem cell graft, thus allowing the evolution of a graft versus malignancy effect post-transplantation. Since September 1999, we had carried out 10 cases of allogeneic peripheral blood stem cell transplantation: one case of aplastic anaemia, four cases of acute myeloid leukemia (AML) in first remission, and five cases of chronic myeloid leukemia (CML) in chronic phase. The preparative regimen was non-myeloablative comprising Fludarabine with Cyclophosphamide or Busulphan. Recovery from transplantation was rapid with no or brief period of neutropenia or thrombocytopenia. Engraftment was established by determining donor's short tandem repeats in the recipient's bone marrow at day 30, 60 and 100 post-transplantation. Seven cases (70%) show partial or complete donor's chimerism by day 30 indicating successful engraftment. No treatment mortality was noted at day 100. Graft versus host disease was generally limited. Up to the date of reporting, two patients with CML had graft failure, one was successfully re-transplanted later. Two patients with AML had since relapsed and passed away. The others remain alive and well. The cost of transplantation on average was estimated to be about a quarter of that using a myeloablative regimen. It appears that this treatment strategy is a promising approach for the management of blood disorders.
  12. Tang YL, Yousuf R, Wan Nawawi WM, Rahman IL, Zainal Abidin J, Rechard Nathan VR, et al.
    Malays J Pathol, 2019 Aug;41(2):161-167.
    PMID: 31427551
    INTRODUCTION: Overnight transfusion (OT) is the blood transfusion taking place from 9pm to 8am. During this period, patients are exposed to increased risk of errors. This cross-sectional study aims to determine the incidence and practice of OT in Universiti Kebangsaan Malaysia Medical Centre.

    MATERIALS & METHODS: Data from all OT in June and mid-July 2017 were collected from recipients' cards, transfusion request forms and patient's case files, regarding discipline involved, indications, time intervals from request of blood transfusion to the completion of OT on patients, monitoring of patients and adverse reactions.

    RESULTS: A total of 1285 transfusion cases were identified during the study period. 216 (16.8%) cases were OT while the 1069 (83.2%) cases were non-OT. Surgery discipline has the highest (30.1%) OT. The indications of OT were acute clinical need: 82.9%, less acute clinical need: 13.9% and no clinical need: 3.2%. A huge delay (average: 5 hours 40 minutes) in starting transfusion after grouping and crossmatching (GXM) completion was noted. Besides, 25.9% cases took <4 hours to complete OT; 83.4% cases did not have proper transfusion monitoring and three transfusion reactions were reported.

    DISCUSSION: Although most of the OT cases had appropriate clinical indications, the transfusion can be commenced earlier at day time rather than overnight. Cases without absolute indication should avoid OT. The poor monitoring of patient during OT had posed risks to patients' life if an adverse transfusion reaction happened. The major reason for OTs was a huge delay in starting transfusion after the GXM completion. The contravention of 4-hour infusion rule increased the patients' risk of developing bacterial sepsis. The practice of OT should be discouraged wherever possible except for clinically indicated cases.

  13. Kuan JW, Su AT, Leong CF, Osato M, Sashida G
    Acta Haematol., 2020;143(2):96-111.
    PMID: 31401626 DOI: 10.1159/000501146
    The treatment of chronic myeloid leukaemia (CML) requires quantitative polymerase chain reaction (qPCR) to monitor BCR-ABL1 in International Scale (IS). Some normal subjects were found to harbour BCR-ABL1. We performed a systematic review on normal subjects harbouring BCR-ABL1. A literature search was done on July 16, 2017 using EBSCOhost Research Databases interface and Western Pacific Region Index Medicus. Two authors selected the studies, extracted the data, and evaluated the quality of studies using the modified Appraisal Tool for Cross-Sectional Studies independently. The outcomes were prevalence, level of BCR-ABL1IS, proportion, and time of progression to CML. The initial search returned 4,770 studies. Eleven studies, all having used convenient sampling, were included, with total of 1,360 subjects. Ten studies used qualitative PCR and one used qPCR (not IS). The mean prevalence of M-BCR was 5.9, 15.5, and 15.9% in cord blood/newborns/infants (CB/NB/I) (n = 170), children (n = 90), and adults (n = 454), respectively, while m-BCR was 15, 26.9, and 23.1% in CB/NB/I (n = 786), children (n = 67), and adults (n = 208), respectively. No study reported the proportion and time of progression to CML. Nine studies were graded as moderate quality, one study as poor quality, and one study as unacceptable. The result of the studies could neither be inferred to the general normal population nor compared. Follow-up data were scarce.
  14. Leong CF, Raudhawati O, Cheong SK, Sivagengei K, Noor Hamidah H
    Pathology, 2003 Oct;35(5):422-7.
    PMID: 14555387
    AIMS: Epithelial membrane antigen (EMA) or MUC1 belongs to a heterogeneous group of heavily glycosylated proteins and is expressed in most normal and epithelial neoplastic cells. EMA is also expressed in plasma cells, anaplastic large cell lymphoma (Ki-1 antigen), malignant histiocytosis and erythroleukaemia. In 1996, Cheong et al. (Hematology 1996; 1: 223) demonstrated the positive expression of EMA in monoblasts. Since there were very few useful markers for differentiating subtypes of acute myeloid leukaemia with a monocytic component from the those without, a study was conducted to evaluate the prevalence of EMA expression and its relationship with known markers for monocytic-macrophage lineage (CD11c, CD14 and intracellular CD68) in monocytes and monoblasts.

    METHODS: EMA detection was performed by flow cytometry in monocytes and monoblasts. EMA expression was compared with other known markers of monocytic-macrophage lineage (CD11c, CD14 and intracellular CD68). Samples of purified monocytes were obtained from 20 healthy volunteers. Twenty-two cases of monocytic AML (M4 and M5) were studied and controls were selected from 20 cases of acute lymphoblastic leukaemia (ALL) and 18 cases of non-monocytic AML (M0, M1, M2, M3, and M7).

    RESULTS: EMA was shown to be expressed strongly on the surface of all purified monocytes. EMA expression was observed on blast cells in 18/22 (81.8%) cases of AML M4 and M5, but not in that of non-monocytic AML or ALL. In this study EMA monoclonal antibody has demonstrated a strong association (P<0.001) with all the other known markers of monocytic-macrophage lineage in acute leukaemia subtypes. EMA had also shown 100% specificity and 81.8% sensitivity in the diagnosis of AML M4 and M5.

    CONCLUSIONS: The monoclonal antibody EMA (clone E29) is a useful marker in the classification of acute myeloid leukaemia and can be used as a supplementary analysis for the diagnosis of acute leukemia with monocytic involvement.

  15. Yap E, Norziha ZA, Simbun A, Tumian NR, Cheong SK, Leong CF, et al.
    Leuk. Res., 2017 08;59:32-40.
    PMID: 28544907 DOI: 10.1016/j.leukres.2017.05.015
    Chronic myeloid leukemia (CML) patients who do not achieve landmark responses following treatment with imatinib mesylate (IM) are considered IM-resistant. Although IM-resistance can be due to BCR-ABL kinase domain (KD) mutations, many IM-resistant patients do not have detectable BCR-ABL KD mutations. MicroRNAs (miRNAs) are short non-coding RNAs that control gene expression. To investigate the role of miRNAs in IM-resistance, we recruited 8 chronic phase CML patients with IM-resistance who tested negative for BCR-ABL KD mutations and 2 healthy normal controls. Using miRNA sequencing, we identified 54 differentially expressed miRNAs; 43 of them downregulated. The 3 most differentially downregulated miRNAs were miR-146a-5p, miR-99b-5p and miR-151a-5p. Using real-time quantitative reverse transcriptase-polymerase chain reaction, the expression patterns of the 3 miRNAs were validated on the same cohort of 8 patients in addition to 3 other IM-resistant CML patients. In-silico analysis showed that the predicted gene targets are ATRIP, ATR, WDR48, RAD51C and FANCA genes which are involved in the Fanconi Anemia/BRCA pathway. This pathway regulates DNA damage response (DDR) and influences disease response to chemotherapy. Thus it is conceivable that DDR constitutes a key component in IM-resistance. Further research is needed to elucidate miRNA modulation of the predicted gene targets.
  16. Tang YL, Chia WK, Yap EC, Julia MI, Leong CF, Salwati S, et al.
    Malays J Pathol, 2016 Dec;38(3):315-319.
    PMID: 28028303 MyJurnal
    INTRODUCTION: Individuals who are exposed to cytotoxic agents are at risk of developing therapyrelated myeloid neoplasms (t-MN). Cytogenetic findings of a neoplasm play an important role in stratifying patients into different risk groups and thus predict the response to treatment and overall survival.

    CASE REPORT: A 59-year-old man was diagnosed with acute promyelocytic leukaemia. Following this, he underwent all-trans retinoic acid (ATRA) based chemotherapy and achieved remission. Four years later, the disease relapsed and he was given idarubicin, mitoxantrone and ATRA followed by maintenance chemotherapy (ATRA, mercaptopurine and methotrexate). He achieved a second remission for the next 11 years. During a follow-up later, his full blood picture showed leucocytosis, anaemia and leucoerythroblastic picture. Bone marrow examination showed hypercellular marrow with trilineage dysplasia, 3% blasts but no abnormal promyelocyte. Fluorescence in-situ hybridisation (FISH) study of the PML/RARA gene was negative. Karyotyping result revealed complex abnormalities and monosomal karyotype (MK). A diagnosis of therapy-related myelodysplastic syndrome/myeloproliferative neoplasm with unfavourable karyotypes and MK was made. The disease progressed rapidly and transformed into therapy-related acute myeloid leukaemia in less than four months, complicated with severe pneumonia. Despite aggressive treatment with antibiotics and chemotherapy, the patient succumbed to the illness two weeks after the diagnosis.

    DISCUSSION AND CONCLUSION: Diagnosis of t-MN should be suspected in patients with a history of receiving cytotoxic agents. Karyotyping analysis is crucial for risk stratification as MK in addition to complex aberrant karyotypes predicts unfavourable outcome. Further studies are required to address the optimal management for patients with t-MN.

  17. Yousuf R, Mustafa AN, Ho SL, Tang YL, Leong CF
    Asian J Transfus Sci, 2017 3 21;11(1):62-64.
    PMID: 28316444 DOI: 10.4103/0973-6247.200770
    The G antigen of Rh blood group system is present in almost all D-positive or C-positive red cells but absent from red cells lacking D and C antigens. The differentiation of anti-D and anti-C from anti-G is not necessary for routine transfusion; however, during pregnancy, it is important because anti-G can masquerade as anti-D and anti-C with initial antibody testing. The false presence of anti-D will exclude the patient from receiving anti-D immunoglobulin (RhIG) when the patient actually is a candidate for RhIG prophylaxis. Moreover, patients with positive anti-D or anti-G are at risk of developing hemolytic disease of the fetus and newborn and need close monitoring. Thus, proper identification allows the clinicians to manage patients properly. This case report highlights a rare case of anti-G together with anti-D and anti-C in a pregnant woman. This report disseminates knowledge on identification of anti-G and its importance in pregnant women.
  18. Kuan JW, Su AT, Leong CF, Osato M, Sashida G
    Int J Hematol, 2019 Jan;109(1):130.
    PMID: 30406326 DOI: 10.1007/s12185-018-2556-6
    The author would like to correct the error in the publication of the original article. The corrected detail is given below for your reading.
  19. Nyunt WWT, Remli R, Abdul Muttlib FA, Leong CF, Masir N, Tumian NR, et al.
    Malays J Pathol, 2017 Dec;39(3):297-303.
    PMID: 29279594 MyJurnal
    POEMS syndrome is the syndrome of Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein and typical Skin changes. A 65-year-old lady presented with the 2-day-history of inability to walk, 4-month-history of progressive worsening of muscle weakness of both lower limbs and 1-year-history of progressive worsening of bilateral numbness of lower limbs. Nerve conduction study revealed generalized sensorimotor demyelinating polyneuropathy. She was initially treated as chronic inflammatory demyelinating polyradiculoneuropathy with intravenous immunoglobulin (IVIG) and high-dose prednisolone. However, she had no significant neurological improvement despite getting standard therapy. In addition to peripheral neuropathy, the presence of hepatosplenomegaly, skin changes, polycythaemia and thrombocytosis prompted for further investigations. She was diagnosed as POEMS syndrome based on the presence of two mandatory major criteria [polyneuropathy, monoclonal plasma cell proliferative disorder (lambda)], one major criterion (sclerotic bone lesions) and three minor criteria (organomegaly, skin changes and thrombocytosis/polycythaemia). She received treatment with melphalan and prednisolone. She achieved clinical improvement and partial response (haematologic and radiological) after six cycles of therapy. We highlight the awareness of this rare syndrome, for patients presenting with peripheral neuropathy and not responding to its standard therapy, by recognizing other associated clinical manifestations and proceeding further diagnostic work-up.
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