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  1. Phenotype and TCR-gamma gene rearrangements in a Malaysian cohort of T-cell leukaemia/lymphoma cases
    Maha A, Gan GG, Koh CL
    Hematology, 2010 Dec;15(6):382-90.
    PMID: 21114900 DOI: 10.1179/102453310X12719010991902
    T cells undergo a series of complex phenotypic changes before achieving maturation. Discrete stages of T-cell differentiation are simplified to four stages (pro-, pre-, cortical and mature-T cell) and used in the classification of T-cell leukaemia. HLA-DR has been reported to be expressed in immature T-cell acute lymphoblastic leukemia (ALL) and also confer a poorer treatment outcome. Simultaneously, the genotype goes through distinct pattern changes due to rearrangement of T-cell receptor (TCR) genes. TCR gene rearrangement is important in the diagnosis of clonality and used as markers to detect minimal residual disease in lymphoproliferative disorders. We identified a subset within Pro-T and Pre-T cell cases distinguished by the expression of HLA-DR. These subgroups appeared to be more immature as rearrangement of the TCR-gamma gene was either at germline or involved only the first constant region (C1) unlike a more rearranged pattern in the HLA-DR-subgroups. We also observed a higher incidence of mediastinal mass (67%) in the HLA-DR-subgroup in the Pre-T stage. These characteristics may be useful as markers to further refine staging of T-cell ALL and determine prognosis.
  2. Cell viability of acute myeloid leukaemia blasts in culture correlates with treatment outcome
    Maha A, Cheong SK, Leong CF, Seow HF
    Hematology, 2008 Feb;13(1):13-20.
    PMID: 18534060 DOI: 10.1179/102453308X315762
    Despite the advances in understanding the pathophysiology of acute myeloid leukaemia (AML), the cure rate for acute myeloid leukaemia patients remains low. Cytogenetic abnormalities and age are the prognostic factors that guide treatment decisions. However, many AML patients still die. The biological factors that influence treatment outcome are largely unknown. Thus, the objective of our study was to use the in vitro viability test to correlate with treatment outcome. Acute myeloid leukaemia blasts demonstrated differing ability to survive in culture. Our examination of blast phenotype at various days in culture showed two possible growth directions. First, cells underwent maturation by increased expression of CD16 and down-regulated CD34 (a haemopoietic stem cell marker). These cells also appeared to have undergone apoptosis. Alternatively, cells continued to survive in culture and maintained high expression of CD34. An MTT assay was carried out to determine viability after three days of culture. Lower optical density values were obtained for samples that underwent apoptosis and higher values were obtained for samples that survived in culture. Apoptosis was measured by Annexin V/propidium iodide staining. A comparison between results of MTT assay and duration of disease free survival revealed that a higher viability in vitro correlated significantly with shorter survival duration in the patient (R -0.761, p=0.002, n=13). Thus, this study further supports the hypothesis that AML patients with poor survival may be related to having blasts with a biologically more immature or stem cell-like nature.
  3. Expression of multidrug resistance (MDR) proteins and in vitro drug resistance in acute leukemias
    Fazlina N, Maha A, Jamal R, Zarina AL, Cheong SK, Hamidah H, et al.
    Hematology, 2007 Feb;12(1):33-7.
    PMID: 17364990
    The expression of the multidrug resistance (MDR) proteins may influence the outcome of treatment in patients with acute leukemia. The aim of this study was to determine the IC50 of cytotoxic drugs (cytosine arabinoside, ara-C and daunorubicin, dnr) using the in vitro 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)2H-tetrazolium, inner salt (MTS) assay method. A total of 82 newly diagnosed acute leukemia cases (43 adult myeloid leukaemia, AML cases and 39 acute lymphoblastic leukaemia, ALL cases) and 16 relapsed cases (8 AML cases and 8 ALL cases) were studied. The MTS assay was performed using two cytotoxic drugs, dnr and ara-C. Cells were incubated with different concentrations of drugs for 4 days and the IC50 was extrapolated from the viability curve. In newly diagnosed cases, we found that childhood ALL samples showed higher IC50 values of dnr (0.040 +/- 2.320) compared to adult AML samples (0.021 +/- 0.158). In contrast, newly diagnosed adult AML samples showed higher IC50 values of ara-C (0.157 +/- 0.529) compared to childhood ALL samples (0.100 +/- 2.350). In relapsed cases, two samples of childhood ALL showed IC50 values of dnr (0.910 +/- 1.760) and ara-C (1.310 +/- 2.390), which was higher compared to childhood AML samples (0.129 +/- 0.214 and 0.210 +/- 0.003, respectively). However, there was no correlation between IC50 values of these drugs tested with clinical outcome. In conclusion, we found that MTS assay is an easy, rapid and non laborious method to study in vitro drug resistance in acute leukaemia cases.
  4. G6PD deficiency with hemolytic anemia due to a rare gene deletion--a report of the first case in Malaysia
    Ainoon O, Boo NY, Yu YH, Cheong SK, Hamidah HN
    Hematology, 2006 Apr;11(2):113-8.
    PMID: 16753852 DOI: 10.1080/10245330500155184
    A 2-year-old Chinese boy was referred to Hospital UKM for investigation of recurrent episodes of dark-coloured urine and pallor since birth. He was born prematurely at 34 weeks gestation and developed severe early-onset neonatal jaundice requiring exchange blood transfusion. Screening at birth showed Glucose-6-phosphate dehydrogenase (G6PD) deficiency. On admission, physical examination revealed pallor, jaundice and mild hepatomegaly. Results of laboratory investigations showed a hemoglobin level of 11.0 g/dl with a hemolytic blood picture, reticulocytosis of 20% and red cell G6PD activity reported as undetectable. The patient's DNA was analysed for G6PD mutations by PCR-based techniques and DNA sequencing and results showed a 24 bp deletion of nucleotide 953-976 in the exon 9 of the G6PD gene. DNA analysis was also performed on blood samples of the patient's mother and female sibling confirming their heterozygous status, although both showed normal red cell G6PD activity levels. The patient was discharged well and his parents were appropriately advised on the condition and the importance of taking folic acid regularly. This is a first case report in Malaysia of G6PD deficiency causing chronic-hemolytic anemia. The rare 24 bp deletion causes the G6PD Nara variant, previously reported only in two other unrelated males, a Japanese and a Portuguese both with chronic hemolytic anemia.
  5. Increased regulatory T cells in acute lymphoblastic leukaemia patients
    Idris SZ, Hassan N, Lee LJ, Md Noor S, Osman R, Abdul-Jalil M, et al.
    Hematology, 2016 May;21(4):206-12.
    PMID: 26907959 DOI: 10.1080/10245332.2015.1101965
    INTRODUCTION: Regulation in adaptive immune response balances a fine line that prevents instigation of self-damage or fall into unresponsiveness permitting abnormal cell growth. Mechanisms that keep this balance in check include regulatory T cells (Tregs). Tregs consist of a small but heterogeneous population, which may be identified by the phenotype, CD3+CD4+CD25+CD127-. The role of Tregs in pathogenesis of cancers is thus far supported by evidence of increased Tregs in various cancers and may contribute to poorer prognosis. Tregs may also be important in acute leukaemias.

    OBJECTIVE: A review of the literature on Tregs in acute leukaemias was conducted and Tregs were determined in B-cell acute lymphoblastic leukaemias (ALLs).

    RESULTS: Studies on Tregs in B-cell ALL are few and controversial. We observed a significantly increased percentage of Tregs (mean±SD, 9.72 ± 3.79% vs. 7.05 ± 1.74%; P = 0.047) in the bone marrow/peripheral blood of ALL (n = 17) compared to peripheral blood of normal controls (n = 35). A positive trend between Tregs and age (R = 0.474, P = 0.055, n = 17) implicates this factor of poor prognosis in B-cell ALL.

    DISCUSSION: Tregs in cancer are particularly significant in immunotherapy. The manipulation of the immune system to treat cancer has for a long time ignored regulatory mechanisms inducible or in place. In lymphoma studies, tumour-specific mechanisms that are unlike conventional methods in the induction of Tregs have been hypothesized. In addition, tumour-infiltrating Tregs may present different profiles from peripheral blood pictures. Tregs will continue to be dissected to reveal its mysteries and their impact on clinical significance.

  6. Fusion genes in malignant neoplastic disorders of haematopoietic system
    Saleem M, Yusoff NM
    Hematology, 2016 Oct;21(9):501-12.
    PMID: 26871368 DOI: 10.1080/10245332.2015.1106816
    OBJECTIVES: The new World Health Organization's (WHO) classification of haematopoietic and lymphoid tissue neoplasms incorporating the recurrent fusion genes as the defining criteria for different haematopoietic malignant phenotypes is reviewed. The recurrent fusion genes incorporated in the new WHO's classification and other chromosomal rearrangements of haematopoietic and lymphoid tissue neoplasms are reviewed.

    METHODOLOGY: Cytokines and transcription factors in haematopoiesis and leukaemic mechanisms are described. Genetic features and clinical implications due to the encoded chimeric neoproteins causing malignant haematopoietic disorders are reviewed.

    RESULTS AND DISCUSSION: Multiple translocation partner genes are well known for leukaemia such as MYC, MLL, RARA, ALK, and RUNX1. With the advent of more sophisticated diagnostic tools and bioinformatics algorithms, an exponential growth in fusion genes discoveries is likely to increase.

    CONCLUSION: Demonstration of fusion genes and their specific translocation breakpoints in malignant haematological disorders are crucial for understanding the molecular pathogenesis and clinical phenotype of cancer, determining prognostic indexes and therapeutic responses, and monitoring residual disease and relapse status.

  7. Relapsed Acute Lymphoblastic Leukemia Presenting as Optic Neuritis
    Fadilah SA, Raymond AA, Cheong SK, Faridah A
    Hematology, 2001;6(4):267-9.
    PMID: 27414846 DOI: 10.1080/10245332.2001.11752124
    Leukemic infiltration of the optic nerve is rare [1]. [Camera, A., Piccirillo, G., Tranfa, F., Rosa, N., Frigeri, F., Martinelli, V., Rotoloi, B. (1993) "Optic nerve involvement in acute lymphoblastic leukemia", Leuk. Lymph. 11, 153-155]. Radiotherapy should be given urgently to all patients with optic nerve infiltrate to restore their vision [2]. [Rosenthal, A. (1983) "Ocular manifestation of leukemia", Ophthalmology 90, 899-905]. We report a case of a unilateral optic nerve relapse 7 months after diagnosis of acute lymphoblastic leukemia (ALL) in a 17-year-old boy who had been off treatment for 6 weeks. The ocular symptoms was initially diagnosed as primary optic neuritis and treated with corticosteroids resulting in temporary clinical recovery. Radiation therapy for ocular leukemia that was commenced 2 months after the onset of symptoms failed to reverse the visual loss. The lack of a reliable and effective tool to diagnose ocular leukemia at an early stage has resulted in significant treatment delay and poor visual outcome.
  8. Nocardiosis Causing Hypocellular Bone Marrow after Allogeneic Peripheral Blood Stem Cell Transplantation
    Fadilah SA, Cheong SK, Raymond AA, Norlela S
    Hematology, 2001;6(5):337-9.
    PMID: 27405528 DOI: 10.1080/10245332.2001.11746588
    Nocardia infection is rare in bone marrow transplant (BMT) recipients with less than 30 cases reported in the literature [1-4]. The majority of the cases occurred late in the post-transplant period. Common clinical presentations included formation of widespread and multiple abscesses. Bone marrow hypoplasia is an uncommon finding. We describe the first case of nocardiosis, diagnosed at day 100 after non-myeloablative allogeneic peripheral blood stem cell transplantation, presenting as pancytopenia and hypocellular marrow. Eradication of the infection with antibiotics resulted in complete hematological recovery.
  9. Multiple Myeloma Presenting with Crystal Deposition in the Bone Marrow
    Fadilah SA, Cheong SK
    Hematology, 1998;3(6):465-8.
    PMID: 27420333 DOI: 10.1080/10245332.1998.11746420
    Monoclonal immunoglobulin deposition disease (MIDD) is characterized by the deposition of amorphous non-congophilic materials predominantly in the kidneys leading to nephrotic syndrome or renal failure. As with light chain amyloidosis. MIDD is associated with a paraproteinemia. We report a patient suffering from multiple myeloma with IgG kappa paraproteinemia and immunoglobulin deposits predominantly in the bone marrow. The deposits are both as amorphous non-congophilic materials, and in the form of crystals, an observation not reported before.
  10. Unexpected Epithelial Membrane Antigen (EMA) and Cytokeratin Expression in a Case of Infantile Acute Monoblastic Leukaemia
    Cheong SK, Chin SF, Azizon O, Ainoon O, Hamidah NH
    Hematology, 1996;1(3):223-5.
    PMID: 27406616 DOI: 10.1080/10245332.1996.11746308
    A previously healthy eleven month old male Malay infant presented with fever, upper respiratory tract infection and right knee swelling. Pallor, bilateral proptosis, hepatosplenomegaly, multiple scalp swellings and a right cheek swelling were observed. Investigations revealed that he had acute monoblastic leukemia or FAB M5a. Immunophenotyping by flow cytometry showed that the blast cells were positive for CD45, CD13, CD33, HLA-DR, CDllc, CD71, EMA, and Cytokeratin. They were negative for CD34, CD19, CD10, CD22, CD2, CD3, CD4, CD7, CD8, CD61, NK, Glycophorin A, and CD14. The monoblasts were used to evaluate anti-EMA and anti-cytokeratin. They were unexpectedly found to be positive. Acute monoblastic leukaemias are well known to show extramedullary infiltration and this may be their primary mode of presentation. Thus, in immunochemostry, when using EMA and cytokeratin expression in the differential diagnosis of neoplastic diseases, it is important to consider that monoblasts may express these markers as illustrated by this case.
  11. Signet-ring Cell Lymphoma-a Case Report
    Masir N, Cheong SK, Noordin K
    Hematology, 2001;6(3):187-92.
    PMID: 27420125 DOI: 10.1080/10245332.2001.11746571
    A case of signet-ring cell lymphoma diagnosed initially by fine needle aspiration cytology is reported. This rare tumor is a variant of follicular lymphoma, which closely resembles metastatic adenocarcinoma and other tumors which exhibit signet-ring cell appearance. Correct diagnosis can be achieved by careful morphologic analysis together with positive reactivity with lymphoid markers. The cytohistologic, immunohistochemical and electron microscopic features are described, and the differ ential diagnostic considerations are discussed in the report.
  12. ADAMTSL5 and CDH11: putative epigenetic markers for therapeutic resistance in acute lymphoblastic leukemia
    Abdullah M, Choo CW, Alias H, Abdul Rahman EJ, Mohd Ibrahim H, Jamal R, et al.
    Hematology, 2017 Aug;22(7):386-391.
    PMID: 28292214 DOI: 10.1080/10245332.2017.1299417
    BACKGROUND AND OBJECTIVES: DNA hypermethylation has been linked to poor treatment outcome in childhood acute lymphoblastic leukemia (ALL). Genes differentially methylated in the chemoresponsive pre-B-ALL compared to chemoresistant pre-B-ALL cases provide potential prognostic markers.

    METHODS: DNA methylation profiles of five B-ALL childhood patients who achieved morphological complete remission (chemoresponsive) and five B-ALL patients who did not (chemoresistant) after induction treatments as well as four normal controls were compared on 27 000 CpG sites microarray chips. Subsequently, methylation-specific polymerase chain reaction (MSP) on selected hypermethylated genes was conducted on an additional 37 chemoresponsive and 9 chemoresistant B-ALL samples and 2 normal controls.

    RESULTS: Both methods were found to be highly correlated. Unsupervised principal component analysis showed that the chemotherapy-responsive and -resistant B-ALL patients could be segregated from one another. Selection of segregated genes at high stringency identified two potential genes (CDH11 and ADAMTSL5). MSP analysis on the larger cohort of samples (42 chemoresponsive, 14 chemoresistant B-ALL samples and 6 normal controls) revealed significantly higher rates of hypermethylation in chemoresistant samples for ADAMTSL5 (93 vs. 38%; p = 0.0001) and CDH11 (79% vs. 40%, p 

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