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Fulltext Comparison of sequences of E/NS1 gene junction of dengue type 3 virus following culture subpassage in C6/36 cells to study the possible occurrence of mutations

Thayan R, Morita K, Vijayamalar B, Zainah S, Chew TK, Oda K, et al.

Southeast Asian J. Trop. Med. Public Health, 1997 Jun;28(2):380-6.
PMID: 9444025

The aim of this study was to determine whether mutations could occur in the dengue virus genome following three subpassages of the virus in a mosquito cell line. This was done because sources of virus isolates used for sequencing studies are usually maintained in cell lines rather than in patients' sera. Therefore it must be assured that no mutation occurred during the passaging. For this purpose, sequencing was carried out using the polymerase chain reaction (PCR) products of the envelope/non-structural protein 1 junction region (280 nucleotides) of dengue type 3 virus. Sequence data were compared between the virus from a patient's serum against the virus subpassaged three times in the C6/36 cell line. We found that the sequence data of the virus from serum was identical to the virus that was subpassaged three times in C6/36 cell line.
The use of polymerase chain reaction (PCR) as a diagnostic tool for dengue virus

Thayan R, Vijayamalar B, Zainah S, Chew TK, Morita K, Sinniah M, et al.

Southeast Asian J. Trop. Med. Public Health, 1995 Dec;26(4):669-72.
PMID: 9139373

This study describes the use of polymerase chain reaction as a diagnostic tool for detecting and typing of dengue virus. PCR was compared against virus isolation. First RT-PCR was done using dengue consensus primers after which positive samples were subjected to RT-PCR using type-specific primers. This study shows that the local strains of the dengue virus could be detected using the chosen primers. Furthermore, RT-PCR was found to be more sensitive than virus isolation in identifying the dengue positive samples.
Isolation of Japanese encephalitis virus from mosquitoes collected in Sabak Bernam, Selangor, Malaysia in 1992

Vythilingam I, Oda K, Chew TK, Mahadevan S, Vijayamalar B, Morita K, et al.

J Am Mosq Control Assoc, 1995 Mar;11(1):94-8.
PMID: 7616198

Detection and isolation of Japanese encephalitis (JE) virus were attempted from female mosquitoes collected in Kampong Pasir Panjang, Sabak Bernam, Selangor, from May to November 1992. A total of 7,400 mosquitoes consisting of 12 species in 148 pools were processed and inoculated into Aedes albopictus clone C6/36 cell cultures. Of these, 26 pools showed the presence of viral antigens in the infected C6/36 cells by specific immunoperoxidase staining using an anti-JE virus polyclonal antibody. Presence of JE virus genome was confirmed in the infected culture fluid for 16 pools by using reverse transcriptase-polymerase chain reaction and JE virus-specific primers. Of these, 3 pools were from Culex tritaeniorhynchus, 4 from Culex vishnui, 3 from Culex bitaeniorhynchus, 2 from Culex sitiens, one from Aedes species, and 3 from Culex species. Isolation of JE virus from Cx. sitiens, Cx. bitaeniorhynchus, and Aedes sp. (Aedes butleri and Ae. albopictus) is reported for the first time in Malaysia.
Microangiopathic haemolytic anaemia and thrombocytopenia due to combined vitamin B12 and folate deficiency masquerading as thrombotic thrombocytopenic purpura

Lee KT, Teoh CS, Chew TK, Goh AS

J R Coll Physicians Edinb, 2020 Jun;50(2):144-147.
PMID: 32568285 DOI: 10.4997/JRCPE.2020.213

Vitamin B12 deficiency and folate deficiency are common causes of macrocytic anaemia and both are important for many cellular processes. These deficiencies could be due to inadequate dietary intake, impaired absorption or drug ingestion. We present a case of a 47-year-old male with a history of diffuse large B-cell lymphoma (DLBCL) who was admitted for fatigue, persistent frontal headache and left upper-quadrant abdominal pain. Further investigation showed that he had pancytopenia with microangiopathic haemolytic anaemia (MAHA) and intracranial bleeding (ICB). Serum vitamin B12 and folate were later found to be low and a diagnosis of combined vitamin B12 and folate deficiency mimicking thrombotic thrombocytopenic purpura (TTP) was made. The patient responded well to vitamin B12 and folate replacement.
Impact of Double Expression of C-MYC/BCL2 Protein and Cell of Origin Subtypes on the Outcome among Patients with Diffuse Large B-Cell Lymphoma: a Single Asian Center Experience

Teoh CS, Lee SY, Chiang SK, Chew TK, Goh AS

Asian Pac J Cancer Prev, 2018 May 26;19(5):1229-1236.
PMID: 29801406

Background: Diffuse large B-cell lymphoma (DLBCL) with double expression of c-MYC and BCL2 protein is
associated with dismal outcome after treatment with R-CHOP. Local data on disease burden and survival outcome in
DLBCL is limited. We investigated the prognostic values of c-MYC/BCL2 protein co-expression and cell of origin
subtypes using immunohistochemistry (IHC) and to determine their associations with multiethnic groups under
resource limited setting. Methods: This was a retrospective study which recruited 104 patients in between June 2012
and December 2015 for IHC review and analysis. Result: We demonstrated that patients with high International
Prognostic Index (IPI) (score 3-5) and co-expression of c-MYC/BCL2 protein had significant inferior overall survival
(OS) and event free survival (EFS) respectively (P<0.05). c-MYC/BCL2 protein co-expression was more common in
non-germinal center B-cell (non-GCB) (P=0.048) and contributed to adverse prognosis in this group of patients (OS,
P=0.004; EFS, P=0.005). In multivariate analysis, double-protein co-expression was a significant independent predictor
of inferior outcome after adjusted for IPI and cell of origin subtypes (OS hazard ratio [HR], 2.11; 95% CI, 1.01 to 4.04;
P=0.048; EFS HR, 2.31; 95% CI, 1.05 to 5.04; P=0.036). In addition, non-GCB subtype was more common than GCB
in Malays (60% vs 40%, P=0.106) and Chinese (81.2% vs 18.8%, P=0.042). Indians had more DLBCL without c-MYC/
BCL2 protein co-expression compared to double-protein positive cases (66.7% vs 33.3%, P=0.414). Otherwise, the
prognostic impact of ethnicity on survival outcome was insignificant (P=0.961). Conclusion: c-MYC/BCL2 protein
co-expression in non-GCB subtype constituted a unique group with extremely inferior outcome regardless of ethnicity.
Gene expression profile (GEP) may possibly provide insights into the cause of discrepancies in DLBCL subtypes and
protein expression among the multiethnic groups.
The epidemiology and clinical characteristics of myeloproliferative neoplasms in Malaysia

Yap YY, Law KB, Sathar J, Lau NS, Goh AS, Chew TK, et al.

Exp Hematol Oncol, 2018;7:31.
PMID: 30564475 DOI: 10.1186/s40164-018-0124-7

Background: The evolution of molecular studies in myeloproliferative neoplasms (MPN) has enlightened us the understanding of this complex disease consisting of polycythaemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The epidemiology is well described in the western world but not in Asian countries like Malaysia.
Materials and methods: This retrospective national registry of MPN was conducted from year 2009 to 2015 in Malaysia.
Results: A total of 1010 patients were registered over a period of 5 years. The mean age was 54 years with male predominance. The ethnic distribution revealed that Chinese had a relatively high weighted incidence proportion (43.2%), followed by Indian (23.8%), Malay (15.8%) and other ethnic groups (17.2%). The types of MPN reported were 40.4% of ET (n = 408), 38.1% of PV (n = 385), 9.2% of PMF (n = 93), 3.1% of hypereosinophilic syndrome (HES) (n = 31) and 7.9% of unclassifiable MPN (MPN-U) (n = 80). Splenomegaly was only palpable clinically in 32.2% of patients. The positive JAK2 V617F mutation was present in 644 patients with 46.6% in PV, 36.0% in ET, 9.0% in PMF, and 7.4% in MPN-U, and had significantly lower haemoglobin (p