Displaying publications 21 - 40 of 68 in total

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  1. 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.
  2. Mok PL, Cheong SK, Leong CF, Othman A
    Cytotherapy, 2008;10(2):116-24.
    PMID: 18368590 DOI: 10.1080/14653240701816996
    Mesenchymal stromal cells (MSC) are pluripotent progenitor cells that can be found in human bone marrow (BM). These cells have low immunogenicity and could suppress alloreactive T-cell responses. In the current study, MSC were tested for their capacity to carry and deliver the erythropoietin (EPO) gene in vitro.
  3. Azma RZ, Hamidah NH, Leong CF, Ainoon O, Cheong SK
    Malays J Pathol, 2006 Dec;28(2):107-12.
    PMID: 18376800
    Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired haemopoietic stem cell disorder arising from somatic mutation of the X-linked PIG-A gene which leads to deficiency of the glycosylphosphatidylinositol (GP1) membrane anchor proteins such as CD 59 (MIRL: membrane inhibitor of reactive lysis) and CD 55 (DAF: decay accelerating factor). Allogeneic peripheral blood stem cell transplant (PBSCT) is a curative mode of treatment in symptomatic PNH patients. Assessment of donor chimerism for PBSCT can be performed by various methods including short tandem repeat loci (STR) and variable number of tandem repeats (VNTR). Flow cytometry, which is much cheaper and faster, also can be used to assess engraftment in patients with PNH. Engrafted patients will show the presence of CD 55 and CD 59 on their red cells and white cells. We describe here the usefulness of flow cytometry in the assessment of donor chimerism following allogeneic PBSCT, in a case of PNH.
  4. Ng SP, Leong CF, Nurismah MI, Shahila T, Jamil MA
    Med J Malaysia, 2006 Aug;61(3):363-5.
    PMID: 17240592 MyJurnal
    A 20 year-old woman presented with features of a twisted ovarian cyst and had an emergency laparotomy Intraoperative findings revealed bilateral, solid ovarian tumors and a left oophorectomy with biopsy of the contralateral ovary performed. Histopathology report confirmed Burkitt lymphoma of ovary. There was no other evidence of lymphoma elsewhere. The primary Burkitt lymphoma of the ovaries was successfully managed with six courses of highly toxic chemotherapy (Berlin-Frankfurt- Munster 1986 protocol). The patient has remained disease free for the last 36 months.
  5. Fadilah SA, Raja-Zahratul-Azma RS, Leong CF
    Malays J Pathol, 2006 Jun;28(1):55-8.
    PMID: 17694960 MyJurnal
    Intense myelofibrosis is rarely associated with de novo acute myeloid leukaemia (AML) except in acute megakaryoblastic leukaemia (AML-M7) where there is diffuse marrow fibrosis as a consequence of proliferation of neoplastic myeloid cells. AML associated with significant myelofibrosis developing both de novo or secondary to primary (idiopathic) myelofibrosis is characterised by a fulminant course and extremely poor prognosis, primarily due to treatment-resistant disease. The prognostic value of degree of marrow fibrosis in de novo AML has been poorly investigated. We describe a case of extensive myelofibrosis associated with acute erythroblastic leukaemia (AML-M6) that responded to induction therapy of the leukaemia.
  6. Fadilah SA, Raymond AA, Leong CF, Cheong SK
    Med J Malaysia, 2006 Mar;61(1):91-3.
    PMID: 16708741
    Haemophagocytic syndrome (HPS) should be included in the differential diagnosis of pyrexia of unknown origin (PUO). The hallmark of HPS is the accumulation of activated macrophages that engulf haematopoietic cells in the reticuloendothelial system. We describe a patient with unexplained fever in which a final diagnosis of HPS was established in a bone marrow study.
  7. Leong CF, Azma RZ, Cheong SK, Salwati S, Sharifah NA
    Malays J Pathol, 2005 Jun;27(1):45-50.
    PMID: 16676693
    A 25-year-old man was referred to Hospital UKM with a 2-week history of fever, productive cough and loss of appetite. Physical examination revealed an ill-looking, tachypnoeic young man. No obvious lymphadenopathy or organomegaly was noted. Examination of the respiratory system revealed right pleural effusion. Full blood picture demonstrated leukocytosis with 90% blasts, and bone marrow examination confirmed the diagnosis of acute myeloid leukemia (AML) French-American-British (FAB) classification of M4 with eosinophilia. His chromosome karyotyping showed complex karyotypic abnormalities. Cytological examination of the pleural fluid demonstrated numerous blast cells indicating leukemic infiltration of the lungs, which is a rare presentation in AML. He was then started on induction chemotherapy with intravenous daunorubicin and cytarabine. In the midst of treatment, he developed an episode of seizure and cerebro-spinal fluid cytology confirmed central nervous system (CNS) leukaemic infiltration. Additional intrathecal methotraxate was given. Repeat bone marrow examination done on day 15 of chemotherapy showed persistence of excess blasts indicating refractory AML. He was then reinduced with high dose cytarabine but to no avail. The disease progressed and he succumbed about 8 weeks after the initial diagnosis was made. We highlight here a case of AML-M4Eo with complex karyoyptic abnormalities presenting with leukaemic infiltration of the lungs and CNS which had imparted a bad prognosis for this subtype of AML, AML-M4Eo.
  8. Lim MN, Leong CF, Cheong SK, Seow HF
    Malays J Pathol, 2003 Dec;25(2):107-12.
    PMID: 16196366
    Dendritic cells (DC) are efficient and potent antigen-presenting cells. Pilot clinical trials indicated that DC loaded with tumour antigen could induce tumour-specific immune responses in various cancers including B-cell lymphoma, melanoma and prostate cancer. Owing to extensively low number of DC in the blood circulation, a variety of sources have been used to generate DC including monocytes, CD34+ stem cells and even with leukaemic blast cells. We demonstrate here a simple method to generate DC from acute myeloid leukaemia (AML) cells and monocytes from healthy donor or remission samples. AML cells or monocytes were cultured in RPMI 1640 media supplemented with foetal bovine serum or autologous serum where possible and different combinations of cytokines GM-CSF, IL-4 and TNF-alpha. The generated DC were evaluated for their morphology by phase contrast microscopy and May Grunwald Giemsa staining. Viability of cells was determined by trypan blue dye exclusion. Percentage of yields and immunophenotypes were carried out by flow cytometry. We found that cultured AML cells and monocytes developed morphological and immuno-phenotypic characteristics of DC. Monocytes are better than AML blast in generating DC and serve as a ready source for dendritic cell vaccine development.
  9. Leong CF, Cheong SK, Hamidah NH, Ainoon O, Kannaheswary Y
    Malays J Pathol, 1998 Dec;20(2):103-8.
    PMID: 10879271
    A 40-day-old baby girl presented with intermittent fever, lymphadenopathy, massive hepatosplenomegaly, progressive pancytopenia and features of disseminated intravascular coagulopathy. A bone marrow aspiration was performed and showed florid histiocytic proliferation with marked hemophagocytosis. Based on the diagnostic guideline for Hemophagocytic Lymphohistiocytosis proposed by the Familial Hemophagocytic Lymphohistiocytosis Study Group of Histiocyte Society, this patient has fulfilled most of the criteria. We have also found that serum ferritin and lactate dehydrogenase to be very high in this patient. It remains uncertain whether the disorder is reactive or neoplastic.
  10. Leong CF, Soo PY, Fadilah SAW, Cheong SK
    Med J Malaysia, 2003 Mar;58(1):131-4.
    PMID: 14556340
    A 49 year-old Indian housewife was diagnosed with Hodgkin's disease in 1995. She was given combination chemotherapy comprising Chlorambucil, Vincristine, Procarbazine and Prednisolone. Unfortunately she defaulted after two courses of chemotherapy. One year later, she developed progressive right knee swelling and pain, associated with loss of appetite, loss of weight, intermittent fever, night sweats and pruritus. The right knee swelling measured 15 cm x 20 cm and was warm and tender. A plain radiograph of the right knee revealed osteolytic lesions at the distal end of the right femur and the proximal ends of the right tibia and fibula, associated with gross periosteal reaction and soft tissue swelling. Apart from left cervical lymphoadenopathy, examination of other systems was unremarkable. Pelvic bone marrow biopsy was inconclusive. An open biopsy of the lower end of the right femur was consistent with Hodgkin's disease. She was given salvage combination therapy comprising Chlorambucil, Vincristine, Procarbazine, Prednisolone, Doxorubicin, Bleomycin and Vinblastine. She tolerated the treatment well and responded with significant reduction in the swelling and pain of the right knee. Unfortunately, she again defaulted treatment after 2 courses of chemotherapy. This case illustrates an unusual presentation of Hodgkin's disease in relapse.
  11. Leong CF, Cheong SK, Ng P, Amran AR
    Hosp Med, 2003 Nov;64(11):686-7.
    PMID: 14671884
  12. Wong CY, Cheong SK, Mok PL, Leong CF
    Pathology, 2008 Jan;40(1):52-7.
    PMID: 18038316
    AIMS: Adult human bone marrow contains a population of mesenchymal stem cells (MSC) that contributes to the regeneration of tissues such as bone, cartilage, muscle, tendon, and fat. In recent years, it has been shown that functional stem cells exist in the adult bone marrow, and they can contribute to renal remodelling or reconstitution of injured renal glomeruli, especially mesangial cells. The purpose of this study is to examine the ability of MSC isolated from human bone marrow to differentiate into mesangial cells in glomerular injured athymic mice.

    METHODS: MSC were isolated from human bone marrow mononuclear cells based on plastic adherent properties and expanded in vitro in the culture medium. Human mesenchymal stem cells (hMSC) were characterised using microscopy, immunophenotyping, and their ability to differentiate into adipocytes, chondrocytes, and osteocytes. hMSC were then injected into athymic mice, which had induced glomerulonephropathy (GN).

    RESULTS: Test mice (induced GN and infused hMSC) were shown to have anti-human CD105(+) cells present in the kidneys and were also positive to anti-human desmin, a marker for mesangial cells. Furthermore, immunofluorescence assays also demonstrated that anti-human desmin(+) cells in the glomeruli of these test mice were in the proliferation stage, being positive to anti-human Ki-67.

    CONCLUSIONS: These findings indicate that hMSC found in renal glomeruli differentiated into mesangial cells in vivo after glomerular injury occurred.

  13. Yousuf R, Abdul Ghani SA, Abdul Khalid N, Leong CF
    Malays J Pathol, 2018 Apr;40(1):27-32.
    PMID: 29704381 MyJurnal
    INTRODUCTION: 'InTec Blood Grouping Test kit' using solid-phase technology is a new method which may be used at outdoor blood donation site or at bed side as an alternative to the conventional tile method in view of its stability at room temperature and fulfilled the criteria as point of care test. This study aimed to compare the efficiency of this solid phase method (InTec Blood Grouping Test Kit) with the conventional tile method in determining the ABO and RhD blood group of healthy donors.

    METHODS: A total of 760 voluntary donors who attended the Blood Bank, Penang Hospital or offsite blood donation campaigns from April to May 2014 were recruited. The ABO and RhD blood groups were determined by the conventional tile method and the solid phase method, in which the tube method was used as the gold standard.

    RESULTS: For ABO blood grouping, the tile method has shown 100% concordance results with the gold standard tube method, whereas the solid-phase method only showed concordance result for 754/760 samples (99.2%). Therefore, for ABO grouping, tile method has 100% sensitivity and specificity while the solid phase method has slightly lower sensitivity of 97.7% but both with good specificity of 100%. For RhD grouping, both the tile and solid phase methods have grouped one RhD positive specimen as negative each, thus giving the sensitivity and specificity of 99.9% and 100% for both methods respectively.

    CONCLUSION: The 'InTec Blood Grouping Test Kit' is suitable for offsite usage because of its simplicity and user friendliness. However, further improvement in adding the internal quality control may increase the test sensitivity and validity of the test results.

  14. Maha A, Cheong SK, Leong CF, Seow HF
    Objective: Despite much progress in treatment strategies, long term survival of adult ALL is still inferior to that in children. The underlying mechanisms for these differences are largely unknown. Intensification of contemporary therapy has also resulted in many children being over-treated. The action of chemotherapeutic drugs used in the treatment of ALL includes cell cycle dependent agents which are effective on cells that are proliferating. Cell proliferation in haemopoietic cells is controlled by cytokines. Thus, we proposed to study the cell cycle profile of ALL cases and also expression of cytokines to determine their role in affecting treatment outcome in the different age groups.
    Methods: We determined the S-phase fraction from the cell cycle profile by flowcytometry and tested the expressions of cytokine IL-1beta, IL-6, IL-18, IFN-gamma, TNF-alpha and GM-CSF using RT-PCR in de novo ALL cases.
    Results: We found a significantly higher S-phase fraction in samples from children 2-10 years old compared to the older age group (>10 years old) (p=0.001). GM-CSF was found to be expressed in a significantly lower percentage of children compared to adults (p=0.008).
    Conclusion: Our results implied that GM-CSF may have induced cell cycle arrests in adult ALL resulting in a lower percentage of S-phase fraction. This may contribute to the poorer prognosis in adult ALL because non-cycling blasts are less sensitive to some chemotherapeutic drugs.
    Keywords: ALL, S-phase fraction, GM-CSF, age
  15. Shamsudin S, Yousuf R, Tang YL, Ding CH, Leong CF
    Malays J Pathol, 2020 Apr;42(1):59-64.
    PMID: 32342931
    INTRODUCTION: Fresh frozen plasma (FFP) is a blood component containing functional quantities of all coagulation factors stored at -18°C or below. FFP has to be thawed and transfused as soon as possible to prevent the loss of certain coagulation factor activities and to minimise microbial contamination.

    MATERIALS AND METHODS: Thirty units of FFP kept at -20°C were thawed using a 37°C water bath and immediately sampled for baseline Factor II (FII), Factor VIII (FVIII) and fibrinogen activity levels and sterility testing. Each unit was then divided into two smaller bags (i.e. Bag I and Bag II) and kept at 4°C. At 6 hours and Day 3, representative samples were taken from Bag I for coagulation factor activity assays, while at Day 5 representative samples were taken from Bag II for coagulation factor activity assays and sterility testing.

    RESULTS: FII activities at the four time points were 73.43%, 73.73%, 71% and 69.8%, respectively, while FVIII activities were 177.63%, 144.37%, 80.8% and 70.97%, respectively. Fibrinogen levels at the four time points were 3.24 g/L, 3.24 g/L, 3.21 g/L and 3.20 g/L, respectively. All samples were free from microbial contamination even at Day 5.

    CONCLUSION: The mean reduction in FII and fibrinogen activities on Day 5 was 5% and 1%, respectively. However, FVIII activity declined significantly by approximately 60% at Day 5. Despite these reductions, thawed plasma stored for up to 5 days at 4°C is still suitable for use as the coagulation factor activity levels still exceed the minimum release criteria recommended in quality assurance regulations.

  16. Rahana AR, Ng SP, Leong CF, Rahimah MD
    Singapore Med J, 2011 Oct;52(10):734-7.
    PMID: 22009393
    INTRODUCTION: This study evaluated the effect of human semen cryopreservation using an ultra-low temperature technique with a mechanical freezer at -85°C as an alternative method to the conventional liquid nitrogen technique at -196°C.
    METHODS: This was a prospective experimental study conducted in the Medically Assisted Conception unit, Department of Obstetrics and Gynaecology, National University Hospital, Malaysia from January 1, 2006 to April 30, 2007. All normozoospermic semen samples were included in the study. The concentration, motility and percentage of intact DNA of each semen sample were assessed before and after freezing and thawing on Days 7 and 30 post freezing.
    RESULTS: Sperm cryopreservation at -85°C was comparable to the conventional liquid nitrogen technique for a period of up to 30 days in a normozoospermic sample. There was no statistical difference in concentration (Day 7 p-value is 0.1, Day 30 p-value is 0.2), motility (Day 7 p-value is 0.9, Day 30 p-value is 0.5) and proportion of intact DNA (Day 7 p-value is 0.1, Day 30 p-value is 0.2) between the ultra-low temperature technique and conventional liquid nitrogen cryopreservation at Days 7 and 30 post thawing.
    CONCLUSION: This study clearly demonstrates that short-term storage of sperm at -85°C could be a viable alternative to conventional liquid nitrogen cryopreservation at -196°C due to their comparable post-thaw results.
  17. Teh HS, Fadilah SA, Leong CF
    Singapore Med J, 2007 Feb;48(2):e46-9.
    PMID: 17304378
    Transverse myelopathy is one of the rare complications following administration of intrathecal chemotherapy. We report two cases of transverse myelopathy following administration of intrathecal methotrexate and cytarabine arabinoside. One patient was a 17-year-old Malay man who had lymphoblastic lymphoma in the leukaemic phase, while the other patient was a 40-year-old Malay man with relapsed Hodgkin's lymphoma. Both cases demonstrated variability in onset of symptoms, clinical progression and final outcome from the complication.
  18. Lim MN, Lau NS, Chang KM, Leong CF, Zakaria Z
    Singapore Med J, 2007 Oct;48(10):932-8.
    PMID: 17909680
    The multidrug resistance gene, MDR1, is one of the genes responsible for resistance to chemotherapy in the treatment of leukaemia and other cancers. The discovery of RNA interference in mammalian cells has provided a powerful tool to inhibit the expression of this gene. However, very little is known about the transfection of leukaemia cells with short interfering RNA (siRNA) targeted at MDR1. This study aims to evaluate the effectiveness of two chemically-synthesised siRNA in modulating MDR1 gene and inhibiting P-glycoprotein expression in leukaemic cells. We also evaluated two siRNA delivery methods in this study.
  19. Yousuf R, Abdul Aziz S, Yusof N, Leong CF
    Indian J Hematol Blood Transfus, 2014 Sep;30(3):208-10.
    PMID: 25114411 DOI: 10.1007/s12288-012-0211-6
    We report a 47-year-old Malay lady, para 4 + 1, with known medical history of hypertension whom presented at Emergency Department with severe anaemia, most likely secondary to menorrhagia caused by uterine fibroids. Her haemoglobin was 5.5 g/dl and she was transfused with three units of packed cell without any adverse reaction, her haemoglobin level increased to 9.8 g/dl. She was then planned for total abdominal hysterectomy and bilateral salpingo-oophorectomy later. Four months later when she came for the elective surgery, her pre transfusion investigations showed blood group as B Rh D positive, with a probable R1R1 phenotype. Her antibody screening was positive in all the three panel cells. Further testings showed a negative Direct Coomb's test and negative autocontrol, antibody identification showed pan-agglutination reaction on all 11 panel cells with enzyme enhancement. Patient's red cell phenotype was Jk(a-b-). Anti-Jk3 was suspected and further confirmed in the reference laboratory by phenotyping as well as negative urea lysis test. This case report highlights an extremely rare but clinically significant anti-JK3 antibody detected during pretransfusion testing. This phenotype is rare in the white population, more commonly seen in various polynesians. Increased awareness among the blood bank personnel regarding the variability of the blood group phenotype and the capricious nature of the Kidd antibodies may contribute to the better management of these patients.
  20. Yousuf R, Abdul Aziz S, Yusof N, Leong CF
    Indian J Hematol Blood Transfus, 2013 Jun;29(2):65-70.
    PMID: 24426338 DOI: 10.1007/s12288-012-0155-x
    Red blood cell alloimmunization is a common complication among the transfusion recipients. In Malaysia, multiple ethnicity causes genetic heterogeneity among the population which in turn can cause a wide variation of antibody. The objective of this study was to analyse the red cell alloantibody detected during the pre-transfusion testing. This was a cross-sectional study done in the blood bank of Universiti Kebangsaan Malaysia Medical Centre during the period of January-December 2010. The data was retrieved from the hospital laboratory information system. A total of 24,263 patients' blood samples were subjected for pre-transfusion testing. Antibody screening was done using an indirect antiglobulin test method. The positive samples were further identified for antibody specificity. Antibody screening tests were positive in 184 patients out of 24,263 samples with the incidence of 0.76 %. Autoantibodies and alloantibodies were detected in 39/184 (21.2 %) and 140/184 (76.1 %) of the patients respectively. In five patients (2.7 %) the antibody specificity remained undetermined. Total 161 alloantibodies were identified. The suspected Anti-Mia alloantibody was observed most frequently (49/161, 30.4 %) followed by anti-E (30/161, 18.6 %) and anti-D (22/161, 13.7 %). Anti-E and anti-c were the most common combination of multiple alloantibodies. In view of the high incidence of suspected Anti-Mia antibodies, more efforts are needed to look into the techniques for confirmation of the Anti-Mia antibodies. Besides that, we suggested that all multiply transfused patients should be phenotyped for the Rh system and to supply Rh phenotype specific blood in order to limit alloimmunization.
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