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Biomedical subjects

S K Cheong

Publications and source records attributed to S K Cheong.

At least 19 recordsLinked to original sources
PubMed2006

G6PD deficiency with hemolytic anemia due to a rare gene deletion--a report of the first case in Malaysia.

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.

Anemia, Hemolytic↗
PubMed2006

Myelodysplastic syndrome transformed into Acute Lymphoblastic Leukaemia (FAB:L3).

Myelodysplastic syndrome (MDS) is recognized as a preleukaemic disorder with a variable risk of transformation to acute myeloid leukaemia. Usually the blast cells in leukaemia are transformed after MDS displays a myeloid phenotype. Even though lymphoid progression had been reported previously, most displayed myeloid-lymphoid hybrid or early B phenotype. We report a case of an elderly man who had MDS transformed into Acute Lymphoblastic Leukaemia (ALL:L3) which is a rare lymphoid transformation.

Anemia, Refractory↗
PubMed2006

The prognostic value of tissue factor levels in acute ischaemic stroke.

INTRODUCTION: There is no biological marker that can accurately predict the prognosis after an acute ischaemic stroke. The main objective of this study was to evaluate the prognostic value of tissue factor (thromboplastin) levels in first ischaemic stroke. METHODS: This was a prospective study of all patients with first ischaemic stroke conducted from October 2003 to February 2004. Plasma for tissue factor levels was kept at -80 degrees Celsius and was analysed at the end of the study period by an independent person. The activities of daily living (ADL) were assessed by using the Barthel index (BI) on admission and at one month after the stroke onset. Any death or recurrent events were recorded. RESULTS: 50 patients were recruited into the study. The median tissue factor level was 184.5 +/- 97.3 pg/ml. Only age (p-value is 0.027) and middle cerebral artery (MCA) infarcts (p-value is 0.038) were found to be significant independent predictors for severe disability at one month with BI equal to or less than 9. There was no correlation of tissue factor level with BI at one month post-stroke (r equals -0.028, p-value is 0.846) and there was also no significant relationship between levels of tissue factor and recurrent events (p-value is 0.41). CONCLUSION: There is no correlation between tissue factor levels with acute ischaemic stroke outcome.

Acute Disease↗
PubMed2006

Haemophagocytic syndrome presenting as pyrexia of unknown origin.

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.

Adult↗
PubMed2005

The use of mycophenolate mofetil in treating patients with non responding aplastic anemia.

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.

Adult↗
PubMed2005

Congenital dyserythropoietic anaemia type II-like dysplastic anaemia preceding the development of non-Hodgkin lymphoma--a case report.

Anaemia is a frequent complication in patients with haematological malignancies and is caused by a variety of mechanisms including neoplastic cell infiltration into the bone marrow, haemolysis, nutritional deficiencies and defect in erythropoiesis or dysplastic anaemia as a result of the disease itself. However, acquired dysplastic anaemia which mimic congenital dyserythropoietic anaemia (CDA) type II morphology in the bone marrow is very rare. A 41-year-old Chinese man presented with refractory symptomatic anaemia in September 2001. He was clinically pale with no other significant physical finding. His initial peripheral blood picture showed normochromic normocytic anaemia with haemoglobin level of 26g/L, with no evidence of haemolysis and a poor reticulocyte response of 0.6%. Bone marrow aspiration was done and showed congenital dyserythropoietic anaemia (CDA) type II-like morphology. He was treated symptomatically with regular blood transfusions approximately every 3 weeks, until August 2002 when he developed multiple cervical lymphadenopathy with loss of appetite, loss of weight and low grade fever. Biopsy of the lymph node confirmed the diagnosis of small lymphocytic lymphoma. Staging with computed tomography and bone marrow aspirate revealed the infiltration of lymphoma cells into the marrow cavity consistent with the staging of IVB. This case report illustrates that CDA type II-like dysplastic anaemia can preceed the development of lymphoma.

Adult↗
PubMed2005

Complex karyotypic abnormalities in a case of acute myeloid leukaemia--M4Eo.

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.

Adult↗
PubMed2004

Research on cancer diagnosis in Malaysia: current status.

Cancer is a major morbidity and mortality concern in Malaysia. Based on National Cancer Registry data, the Malaysian population is estimated to bear a cancer burden of about 40,000 new cases per year, and a cumulative lifetime risk of about 1:4. Cancer research in Malaysia has to consider needs relevant to our population, and resources constraints. Hence, funding bodies prioritise cancers of high prevalence, unique to our community and posing specific clinical problems. Cancer diagnosis is crucial to cancer management. While cancer diagnosis research largely aims at improvements in diagnostic information towards more appropriate therapy, it also impacts upon policy development and other areas of cancer management. The scope of cancer diagnosis upon which this paper is based, and their possible impact on other R&D areas, has been broadly categorized into: (1) identification of aetiological agents and their linkages to the development of precancer and cancer (impact on policy development, cancer prevention and treatment), (2) cancer biology and pathogenesis (impact on cancer prevention, treatment strategies and product development), (3) improvements in accuracy, sensitivity and specificity in cancer detection, monitoring and classification (impact on technology development) and (4) prognostic and predictive parameters (impact on treatment strategies). This paper is based on data collected by the Working Group on Cancer Diagnosis Research for the First National Conference on Cancer Research Coordination in April 2004. Data was collated from the databases of Institutions/Universities where the authors are employed, the Ministry of Science, Technology and Innovation (MOSTI) and targeted survey feedback from key cancer researchers. Under the 7th Malaysia Plan, 76 cancer projects were funded through the Intensified Research in Priority Areas (IRPA) scheme of MOSTI, amounting to almost RM15 million of grant money. 47(61.8%) of these projects were substantially in cancer diagnosis, accounting for 65.6% (RM 9.7 million) of cancer project funds. The 8th Malaysia Plan saw a change in research strategy. The IRPA agency fielded several top-down projects which encouraged a multicentre and multidisciplinary approach. This resulted in larger funding per project i.e. RM32 million for 49 projects. There was also a surge of interest in drug development and natural products. Because of this shift in direction, cancer diagnosis projects constituted only 51% of IRPA-funded cancer projects. Nonetheless funding for cancer diagnosis research has exceeded that of the 7th Malaysia Plan, being RM12.5 million by March 2004. The majority of such research is carried out at the Universities, engaging a large number of young scientists and postgraduate students (51 MSc and 21 PhD). A lot of research findings presented at scientific meetings have not yet been published and there is a glaring shortage of patents and commercialization of research findings (such as creation of test kits). Because diagnosis is very much a part of clinical practice, many researchers felt satisfied and confident that their work will be translated into practice and will significantly improve diagnostic services in Malaysia. National guidelines and consensus development on at least three malignancies i.e. breast cancer, oral cancer and lymphoma, have substantial basis in local R&D work. Problems encountered in research included (1) insufficient funding to realize research objectives, (2) lack of local expertise (most research assistants are inexperienced BSc graduates with no or minimal research experience), (3) inadequate technical support from vendors during equipment failure, (4) inexperienced Institutional development units to assist in product development, (5) lack of venture capital for commercialization of findings, and (6) inadequate incentives to undertake research. Researchers pointed out that plans to promote research should include the establishment of (1) regional and national cancer tissue banks, (2) a National Cancer Research Institute, (3) a dedicated cancer research fund, (4) a registry of cancer researchers, (5) national research coordinators, (6) improved coverage by the National Cancer Registry, (7) more international collaboration, (8) a better career structure for researchers, (9) improved Institutional support for product realization, and (10) better recognition for cancer researchers.

Humans↗
PubMed2004

Comparison of myeloperoxidase detection by flow cytometry using two different clones of monoclonal antibodies.

INTRODUCTION: 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. METHODS: Anti-MPO were purchased from Dako (Denmark) and Becton Dickinson, BD (California, USA). MPO detection was done using the permeabilisation-staining technique, followed by analysis with flow cytometer (FASCalibur, California, USA). RESULTS: 63 cases of acute leukaemias (38 ALL and 25 AML) were studied. Anti-MPO by Dako showed that 12/38 (31.6%) of ALL cases were positive, but all these cases were clear-cut negative for anti-MPO from BD. 24/38 (63.2%) of these ALL cases were associated with aberrant expression of myeloid antigens. However, only 8/24 (33.3%) cases with aberrant myeloid antigen expression showed positive reaction to anti-MPO (Dako). 23/25 (92%) of AML showed concordance results for both anti-MPO by Dako and BD. CONCLUSION: Anti-MPO is a useful and reliable marker for the diagnosis of AML. However, this study had demonstrated that results vary with the monoclonal antibody used in ALL cases. Anti-MPO (Dako) had shown false positive result in 31.6% of ALL cases whereas anti-MPO (BD) had shown consistent negative result in ALL cases.

Antibodies, Monoclonal↗
PubMed2003

Glucose-6-phosphate dehydrogenase (G6PD) variants in Malaysian Malays.

We performed DNA analysis using cord blood samples on 86 male Malay neonates diagnosed as G6PD deficiency in the National University of Malaysia Hospital by a combination of rapid PCR-based techniques, single-stranded conformation polymorphism analysis (SSCP) and DNA sequencing. We found 37.2% were 871G>A (G6PD Viangchan), 26.7% were nt 563 C>T (G6PD Mediterranean) and 15.1% were 487G>A (G6PD Mahidol) followed by 4.7% 1376G>T (G6PD Canton), 3.5% 383T>C (G6PD Vanua Lava), 3.5% 592C>T (G6PD Coimbra), 2.3% 1388G>A (G6PD Kaiping), 2.3% 1360C>T (G6PD Union), 2.3% 1003G>A (G6PD Chatham), 1.2% 131C>G (G6PD Orissa) and 1.2% 1361G>A (G6PD Andalus). Seventy-one (82.6%) of the 86 G6PD-deficient neonates had neonatal jaundice. Fifty seven (80%) of the 71 neonates with jaundice required phototherapy with only one neonate progressing to severe hyperbilirubinemia (serum bilirubin >340 micromol/l) requiring exchange transfusion. There was no significant difference in the incidence of neonatal jaundice, mean serum bilirubin level, mean age for peak serum bilirubin, percentage of babies requiring phototherapy and mean number of days of phototherapy between the three common variants. In conclusion, the molecular defects of Malay G6PD deficiency is heterogeneous and G6PD Viangchan, Mahidol and Mediterranean account for at least 80% of the cases. Our findings support the observation that G6PD Viangchan and Mahidol are common Southeast Asian variants. Their presence in the Malays suggests a common ancestral origin with the Cambodians, Laotians and Thais. Our findings together with other preliminary data on the presence of the Mediterranean variant in this region provide evidence of strong Arab influence in the Malay Archipelago.

DNA Mutational Analysis↗
PubMed2003

Semiquantitative screening test for G6PD deficiency detects severe deficiency but misses a substantial proportion of partially-deficient females.

Neonatal screening for G6PD deficiency has long been established in many countries. The aim of the study was to determine whether the routine semiquantitative fluorescent spot test could detect all cases of G6PD deficiency, including those cases with partial deficiency (residual red cell G6PD activity between 20-60% of normal). We compared the results of G6PD screening by the semiquantitative fluorescent spot test and quantitative G6PD activity assay on a group of 976 neonates and 67 known female heterozygotes. The values for mean G6PD activity of G6PD-normal neonates and 293 healthy adult females were determined. There was no significant difference in the mean normal G6PD activity between the two racial groups in the neonates (669 Malays, 307 Chinese) and in the 293 healthy adult females (150 Malays, 143 Chinese) group. The values for the upper limits of total deficiency (20% of normal residual activity) for neonates and adult females were 2.92 U/gHb and 1.54 U/gHb, respectively. The upper limits of partial deficiency (60% of normal residual activity) were 8.7 U/gHb and 4.6 U/gHb respectively. The prevalence of G6PD deficiency among the male neonates was 5.1% (26) by both the fluorescent spot test and the enzyme assay method. The G6PD activity levels of all 26 cases of G6PD-deficient male neonates were < 20% normal (severe enzyme deficiency). In the female neonate group, the frequency of G6PD deficiency was 1.3% (6 of 472) by the fluorescent spot test and 9.35% (44 of 472) by enzyme assay. The 6 cases diagnosed as deficient by the fluorescent spot test showed severe enzyme deficiency (< 2.92 U/gHb). The remaining 38 female neonates had partial enzyme deficiency and all were misdiagnosed as normal by the fluorescent spot test. In the female heterozygote group, G6PD deficiency was diagnosed in 53% (35 of 67) by enzyme assay and in 7.5% (4 of 67) of cases by the fluorescent spot test. The 4 cases detected by fluorescent spot test had severe enzyme deficiency (<1.6 U/gHb). The remaining 31 (46.3%) cases, diagnosed as normal by fluorescent spot test, showed partial G6PD deficiency. In conclusion, we found that the semiquantitative fluorescent spot test could only diagnose cases of total G6PD deficiency and misclassified the partially-deficient cases as normal. In this study, the overall prevalence of G6PD deficiency was 3.28% by the semiquantitative fluorescent spot test and 7.17% by enzyme assay. This means that 3.9% of G6PD-deficient neonates were missed by the routine fluorescent spot test and they were found to be exclusively females. This study demonstrates a need to use a method that can correctly classify female heterozygotes with partial G6PD deficiency. The clinical implication is that these individuals may be at risk of the hemolytic complication of G6PD deficiency.

Adult↗
PubMed2003

Leukaemia cutis presenting as leonine facies.

Acute leukaemia may rarely present as diffuse papules, nodules and plaques forming leonine facies. Leukaemia cutis generally carries a poor prognosis, and responds less well to chemotherapy. We described a case of acute myelomonocytic leukaemia presenting as leonine facies as a result of extensive cutaneous infiltration. The patient did not achieve haematological remission following standard induction chemotherapy and succumbed 6 weeks after the diagnosis was made.

Facial Dermatoses↗
PubMed2003

Relapsed Hodgkin's disease presenting as a right knee swelling.

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.

Female↗
PubMed2003

Allogeneic haemopoietic stem cell transplantation using non-myeloablative conditioning--a local experience.

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.

Adolescent↗