Displaying publications 61 - 80 of 98 in total

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  1. Tan J, Lim PE, Phang SM, Hong DD, Sunarpi H, Hurtado AQ
    PLoS One, 2012;7(12):e52905.
    PMID: 23285223 DOI: 10.1371/journal.pone.0052905
    DNA barcoding has been a major advancement in the field of taxonomy, seeing much effort put into the barcoding of wide taxa of organisms, macro and microalgae included. The mitochondrial-encoded cox1 and plastid-encoded rbcL has been proposed as potential DNA barcodes for rhodophytes, but are yet to be tested on the commercially important carrageenophytes Kappaphycus and Eucheuma. This study gauges the effectiveness of four markers, namely the mitochondrial cox1, cox2, cox2-3 spacer and the plastid rbcL in DNA barcoding on selected Kappaphycus and Eucheuma from Southeast Asia. Marker assessments were performed using established distance and tree-based identification criteria from earlier studies. Barcoding patterns on a larger scale were simulated by empirically testing on the commonly used cox2-3 spacer. The phylogeny of these rhodophytes was also briefly described. In this study, the cox2 marker which satisfies the prerequisites of DNA barcodes was found to exhibit moderately high interspecific divergences with no intraspecific variations, thus a promising marker for the DNA barcoding of Kappaphycus and Eucheuma. However, the already extensively used cox2-3 spacer was deemed to be in overall more appropriate as a DNA barcode for these two genera. On a wider scale, cox1 and rbcL were still better DNA barcodes across the rhodophyte taxa when practicality and cost-efficiency were taken into account. The phylogeny of Kappaphycus and Eucheuma were generally similar to those earlier reported. Still, the application of DNA barcoding has demonstrated our relatively poor taxonomic comprehension of these seaweeds, thus suggesting more in-depth efforts in taxonomic restructuring as well as establishment.
  2. Aghakhanian F, Wong C, Tan JSY, Yeo LF, Ramadas A, Edo J, et al.
    Public Health, 2019 Nov;176:106-113.
    PMID: 30509859 DOI: 10.1016/j.puhe.2018.10.001
    OBJECTIVES: This study was undertaken to investigate the occurrence of metabolic syndrome (MetS) and cardiovascular disease (CVD) risk in Orang Asli (OA), the indigenous people of Peninsular Malaysia. OA consist of Negrito, Proto-Malay, and Senoi groups who collectively comprise only 0.76% of the population of Peninsular Malaysia. Owing to the challenges in accessing their remote villages, these groups are often excluded in larger government health surveys. Although tropical diseases were scourges in the past, with rapid national development, many OA communities have been gradually urbanized. We believe an epidemiological transition is occurring and non-communicable diseases are on the rise.

    STUDY DESIGN: A retrospective cross-sectional study.

    METHODS: Indigenous Malaysians (n = 629) from three major groups (Negrito, Proto-Malay, and Senoi) were recruited, after ethics approval and informed consent. Body mass index (BMI), body weight, height, waist circumference, and systolic and diastolic blood pressure were measured, and participants were examined for acanthosis nigricans. Venous blood samples were used for measurements of fasting blood sugar, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Insulin resistance was estimated using a surrogate measurement TG/HDL-C. The ratios of TC to HDL-C, and of LDL-C to HDL-C were determined. MetS was accessed according to the Joint Interim Statement of the IDF Tsak Force on Epidemiology and Prevention.

    RESULTS: MetS affected 29.57% of the OA population investigated and was significantly more prevalent (P 

  3. Yong HS, Lim PE, Tan J, Ng YF, Eamsobhana P, Suana IW
    Sci Rep, 2014 Jul 03;4:5553.
    PMID: 24989852 DOI: 10.1038/srep05553
    Dragonflies of the genus Orthetrum are members of the suborder Anisoptera, family Libellulidae. There are species pairs whose members are not easily separated from each other by morphological characters. In the present study, the DNA nucleotide sequences of mitochondrial and nuclear genes were employed to elucidate the phylogeny and systematics of Orthetrum dragonflies. Phylogenetic analyses could not resolve the various subfamilies of the family Libellulidae unequivocally. The nuclear 28S rRNA gene is highly conserved and could not resolve congeneric species of Orthetrum. Individual mitochondrial genes (COI, COII, and 16S rRNA) and combination of these genes as well as the nuclear ITS1&2 genes clearly differentiate morphologically similar species, such as the reddish species pairs O. chrysis and O. testaceum, and the bluish-coloured species O. glaucum and O. luzonicum. This study also reveals distinct genetic lineages between O. pruinosum schneideri (occurring in Malaysia) and O. pruinosum neglectum (occurring north of Peninsular Malaysia from India to Japan), indicating these taxa are cryptic species.
  4. Lim PE, Tan J, Eamsobhana P, Yong HS
    Sci Rep, 2013 Oct 17;3:2977.
    PMID: 24131999 DOI: 10.1038/srep02977
    The phylogenetic relationships of some taxa in the Platycnemidinae at the species and generic levels have been investigated. Phylogenetic trees were generated from both individual mitochondrial encoded COI, COII, 16S rDNA and nuclear encoded 28S rDNA and also combined sequences; these data indicate that the component taxa of the genus Copera belong to two distinct genetic clades - the marginipes group and the annulata group. There was no distinct genetic difference between the red-legged and yellow-legged morphs of C. vittata. Molecular data showed that the annulata group is considered a member of the genus Platycnemis, as originally proposed. The genus Coeliccia, a member of the subfamily Calicnemiinae (Platycnemididae), is not grouped with the Platycnemidinae. The Disparoneurinae of the 'Protoneuridae' showed a closer relationship to the Platycnemidinae than the Calicnemiinae. The dataset supports the placement of the Disparoneurinae as a subfamily of the Platycnemididae. This resolves the monophyly of Platycnemididae.
  5. Yong HS, Song SL, Chua KO, Wayan Suana I, Eamsobhana P, Tan J, et al.
    Sci Rep, 2021 May 21;11(1):10680.
    PMID: 34021208 DOI: 10.1038/s41598-021-90162-1
    Spiders of the genera Nephila and Trichonephila are large orb-weaving spiders. In view of the lack of study on the mitogenome of these genera, and the conflicting systematic status, we sequenced (by next generation sequencing) and annotated the complete mitogenomes of N. pilipes, T. antipodiana and T. vitiana (previously N. vitiana) to determine their features and phylogenetic relationship. Most of the tRNAs have aberrant clover-leaf secondary structure. Based on 13 protein-coding genes (PCGs) and 15 mitochondrial genes (13 PCGs and two rRNA genes), Nephila and Trichonephila form a clade distinctly separated from the other araneid subfamilies/genera. T. antipodiana forms a lineage with T. vitiana in the subclade containing also T. clavata, while N. pilipes forms a sister clade to Trichonephila. The taxon vitiana is therefore a member of the genus Trichonephila and not Nephila as currently recognized. Studies on the mitogenomes of other Nephila and Trichonephila species and related taxa are needed to provide a potentially more robust phylogeny and systematics.
  6. Balraj P, Khoo AS, Volpi L, Tan JA, Nair S, Abdullah H
    Singapore Med J, 2002 Apr;43(4):194-7.
    PMID: 12188064
    Thirty patients with early onset breast cancer or familial breast cancer from Malaysia were analysed for germline mutation in the early onset breast cancer I gene (BRCA1). Direct sequencing of the entire coding region of BRCA1 identified a frameshift mutation, c.5447-5448insC (insC5447) (codon 1776 of exon 21) in a patient aged 32 of the Malay ethnic origin, who had no family history of breast and/or ovarian cancer. Eight polymorphisms (2201C > T, 2430T > C, P871L, E1038G, K1183R, 4427T > C, S1613G and IVS8-57delT) were identified in the samples tested.
  7. Tan KH, Tan TY, Tan J, Tan I, Chew SK, Yeo GS
    Singapore Med J, 2005 Oct;46(10):545-52.
    PMID: 16172775
    To study characteristics of birth defect cases among live births, stillbirths and abortions in Singapore between 1994 and 2000.
  8. Tan JA, Tay SH, Kham KY, Wong HB
    Jpn. J. Hum. Genet., 1993 Sep;38(3):315-8.
    PMID: 7903173 DOI: 10.1007/BF01874141
    The distribution of restriction fragment length polymorphism (RFLP) at the BamH1 site of the beta-globin gene was investigated in the Chinese, Indian, and Malay race in Singapore. The sample comprised of 183 normal individuals and 35 beta-thalassemia carriers in which 13 were couples with at least one beta-major child. The results from this study indicate that BamH1 polymorphism will be informative in 22% of pregnancies at risk for beta-thalassemia major in Chinese, 19% in Malays and 7% in Indians. In prenatal diagnosis using BamH1 polymorphism for one beta-major affected family, the fetus was diagnosed to be normal or beta-carrier. The validity of BamH1 polymorphism in the exclusion of beta-thalassemia major was subsequently confirmed at birth by globin chain biosynthesis.
  9. Tan J, Mabood Khalil MA, Kee T, Tiong HY, Khan TT, El-Madhoun I, et al.
    PMID: 38361593 DOI: 10.1016/j.lansea.2023.100312
    Deceased donor kidney transplantation (DDKT) is common in high income Western countries with high transplantation rates. However, the utilization of deceased organs is suboptimal in Asia, due to a multitude of factors. Coherent policies are integral to the development of DDKT programs and deterrence of commercialization, but most are still at an infancy and formative stage in Asia. This review article identifies the glass ceiling effects of social, cultural, religious, political, and technical factors hampering the progress of DDKT in Asia. Additionally, it reviews the history of policy development in different countries and describes their idiosyncratic barriers and challenges. Lastly, it discusses innovative policy measures that can be undertaken to proliferate DDKT practice and curtail commercialization. The long-term ideal is to achieve regional equity and self-sufficiency, through a shared ethos of social and ethical responsibility that transcends and resonates with the different segments of the Asian community.
  10. Lim CK, Tan JT, Ravichandran A, Chan YC, Ton SH
    Malays J Pathol, 2007 Dec;29(2):79-90.
    PMID: 19108399 MyJurnal
    Hepatitis B virus (HBV) is classified into eight genotypes (A to H). In this study, three genotyping methods were compared for their sensitivity and accuracy, namely PCR-RFLP on the S region, PCR-RFLP on the pre-S region and nested PCR with type specific primers. Sixty HBV samples from infected sera were genotyped. The nested PCR with type specific primers was found to be the most sensitive and produced substantial numbers of co-infections by genotypes B and C. The sensitivities for both PCR-RFLP methods were lower and did not reveal co-infections. Generally, the three methods produced consistent genotyping results in samples infected by single genotypes but for co-infections by genotypes B and C, the two PCR-RFLP methods yielded only single genotypic results. For the cases of single genotypic infections, genotypes ascertained by sequencing were in concordance across all three methods. However, when co-infections occurred, PCR analysis on clones revealed only single genotypic infections.
  11. Tan HCL, Tan JH, Vellusamy VM, Vasavan Y, Lim CS
    Malays J Pathol, 2020 Aug;42(2):267-271.
    PMID: 32860380
    INTRODUCTION: Majority of Wilms tumour (WT) responds well to pre-operative chemotherapy. In Malaysia, incidence of WT is rare with only two cases reported per one million populations yearly. This case report is to highlight on the awareness of WT in an Asian population and highlight two cases and challenges faced after pre-operative chemotherapy.

    CASE REPORT: In this case series, we report on two cases of WT which had poor response to pre-operative chemotherapy. Both cases underwent surgery after pre-operative chemotherapy and recovery was uneventful during a two-year follow-up.

    DISCUSSION: Both patients had chemotherapy prior planned surgery, but had unfortunate poor tumour response. The tumour progressed in size which required a radical nephrectomy. The histology report for the first case had more than 60% blastemal cells remaining despite giving pre-operative chemotherapy with no focal anaplasia. This showed poor response to chemotherapy evidenced by the high number of blastemal cells. The second case was a stromal type WT which is known for poor response and may lead to enhancement of growth and maturation induced by chemotherapy. These were the possible reason of poor response of WT in these two cases.

  12. Tan JSJ, Ong KC, Ong DBL, Razack A, Lim J, Yunus R, et al.
    Malays J Pathol, 2018 Aug;40(2):103-110.
    PMID: 30173226 MyJurnal
    INTRODUCTION: Prostate cancer is a heterogenous disease and the mechanisms that drive it to behave differently are not well understood. Tumour expression of the ERG oncogene occurs in the majority of patients with prostate cancer in Western studies. This is considered to be oncogenic as ERG acts as a transcription factor to regulate genes involved in tumour proliferation and invasion. In this study we investigated expression of ERG in Malaysian men with prostate cancer.

    METHODS: Tissues were collected from 80 patients with clinically detected prostate cancer and treated with radical prostatectomy. Cases were tested for ERG by immunohistochemistry using the mouse monoclonal antibody EP111. All blocks on 48 cases were tested in order to determine the extent of heterogeneity of ERG expression within individual cases. ERG expression was analysed in relation to patient age, ethnicity and tumour stage and grade.

    RESULTS: Forty-six percent of cases were ERG positive. There was no significant association between ERG and tumour grade or stage. Sixty-nine percent of Indian patients had ERG positive tumours; this was significantly higher (p=0.031) than for Chinese (40%) and Malay (44%) patients. Heterogeneity of ERG expression, in which both positive and negative clones were present, was seen in 35% of evaluated cases. Evaluation by tumour foci showed younger patients had more ERG positive tumour foci than older patients (p=0.01). Indian patients were more likely to have the majority of tumour foci with ERG staining positively, compared to either Chinese or Malay patients (P <0.01).

    CONCLUSION: In this study, tumour expression of ERG was more likely to occur in patients of Indian ethnicity.

  13. Tan JSJ, Ong KC, Ong DBL, Wu YS, Razack A, Kuppusamy S, et al.
    Malays J Pathol, 2019 Dec;41(3):243-251.
    PMID: 31901908
    INTRODUCTION: Polymorphic expression of a CAG repeat sequence in the androgen receptor (AR) gene may influence the activity of the AR and the occurrence of prostate cancer and the TMPRSS2-ERG fusion event. Furthermore, this polymorphism may be responsible for the ethnic variation observed in prostate cancer occurrence and expression of the ERG oncogene. We investigate the expression of AR and ERG in the biopsies of Malaysian men with prostate cancer and in the same patients relate this to the length of the CAG repeat sequence in their AR gene.

    MATERIALS AND METHODS: From a PSA screening initiative, 161 men were shown to have elevated PSA levels in their blood and underwent prostatic tissue biopsy. DNA was extracted from the blood, and exon 1 of the AR gene amplified by PCR and sequenced. The number of CAG repeat sequences were counted and compared to the immunohistochemical expression of ERG and AR in the matched tumour biopsies.

    RESULTS: Of men with elevated PSA, 89 were diagnosed with prostate cancer, and 72 with benign prostatic hyperplasia (BPH). There was no significant difference in the length of the CAG repeat in men with prostate cancer and BPH. The CAG repeat length was not associated with; age, PSA or tumour grade, though a longer CAG repeat was associated with tumour stage. ERG and AR were expressed in 36% and 86% of the cancers, respectively. There was no significant association between CAG repeat length and ERG or AR expression. However, there was a significant inverse relationship between ERG and AR expression. In addition, a significantly great proportion of Indian men had ERG positive tumours, compared to men of Malay or Chinese descent.

    CONCLUSIONS: CAG repeat length is not associated with prostate cancer or expression of ERG or AR. However, ERG appears to be more common in the prostate cancers of Malaysian Indian men than in the prostate cancers of other Malaysian ethnicities and its expression in this study was inversely related to AR expression.

  14. Tan JS, Ong Kc KC, Rhodes A
    Malays J Pathol, 2016 Aug;38(2):75-82.
    PMID: 27568663 MyJurnal
    Heat shock proteins (HSPs) are a family of evolutionary conserved proteins that work as molecular chaperones for cellular proteins essential for cell viability and growth as well as having numerous cyto-protective roles. They are sub-categorised based on their molecular weights; amongst which some of the most extensively studied are the HSP90 and HSP70 families. Important members of these two families; Heat shock proteins 70 and heat shock proteins 90 (Hsp70/90), are the glucose regulated proteins (GRP). These stress-inducible chaperones possess distinct roles from that of the other HSPs, residing mostly in the endoplasmic reticulum and mitochondria, but they can also be translocated to other cellular locations. Their ability in adapting to stress conditions in the tumour microenvironment suggests novel functions in cancer. GRPs have been implicated in many crucial steps of carcinogenesis to include stabilization of oncogenic proteins, induction of tumour angiogenesis, inhibition of apoptosis and replicative senescence, and promotion of invasion and metastasis.
  15. Tan JT, Letchuman Ramanathan G, Choy MP, Leela R, Lim BK
    Med J Malaysia, 2013 Oct;68(5):384-8.
    PMID: 24632866 MyJurnal
    INTRODUCTION: Paraquat is a quaternary nitrogen herbicide which is highly toxic to human. Death is usually from respiratory failure and may occur within days up to a month after exposure. It is easily available and commonly abused to commit suicide.

    METHODOLOGY: This is a retrospective study describing the demographic characteristics, clinical features and outcomes of paraquat poisoning cases admitted to Hospital Taiping from 1st January 2008 to 30th October 2011. Medical records of 79 patients were reviewed.

    RESULT: Majority were of the Indian ethnicity (72.2%) followed by Chinese (13.9%) and Malay (10.1%). Majority was male (73.4%) and between 20 to 29 years old (34.2%). The median age of the patients was 30 years old. The mean length of stay was 6.2 days. Most exposures were intentional (69.6%) and presented to the hospital early at less than 6 hours after exposure (72.2%). Patients with positive urine paraquat result had significantly higher mortality rate compared to patients with negative results (47.4% vs 15.2% respectively). We found that neither hemofiltration nor immunosuppressive therapies help to improve survival.

    CONCLUSION: The non-survivor characteristics of patients with paraquat poisoning are intentional exposure, delay from exposure to hospital admission, urine paraquat positivity and manifestation of respiratory failure. The demographic characteristics, reasons for exposure and mortality rate are similar to previous reports. Urine paraquat may be used to assess severity of the exposure as well as prognosis. Hemofiltration and immunosuppression therapy do not improve patients' survival and paraquat remains a lethal killer.
  16. George E, Lai MI, Teh LK, Ramasamy R, Goh EH, Asokan K, et al.
    Med J Malaysia, 2011 Dec;66(5):429-34.
    PMID: 22390095 MyJurnal
    Detection and quantification of Hb subtypes of human blood is integral to presumptive identification of thalassaemias. It has been used in neonatal screening of thalassaemia and Hb variants. The use of discarded red blood cells following processing of the cord blood for stem cells provides readily available diagnostic material for thalassaemia screening. In this study, we determined the range of Hb subtypes in 195 consecutive cord blood samples collected for cord blood banking. The 'cord blood samples' analysed were those of the remaining red blood cells after the cord blood was processed for stem cell storage. Quantification of Hb subtypes by high performance liquid chromatography (HPLC) was done on BioRad Variant II Hb testing system. Only 73 (36.5%) of the samples could be analyzed neat without dilution. With a 1:300 dilution with wash solution the acceptable area as recommended by the manufacturer for reading of a C-gram within the 1 to 3 million ranges were achieved in all. Eighteen (9%) 12 showed classical Hb Barts (y4) prerun peaks were confirmed by Sebia Hydrasys automated Hb gel electrophoresis and quantified by Sebia Capillarys 2 capillary electrophoresis. Only 1 (0.5%) was presumptively identified with HbH disease. Due to the limited number of samples no beta-thalassaemia major, Hb E beta-thalassaemia and Hb Barts hydrops fetalis were found. The HPLC assay was possible at a cost US$ 5 per sample and a turnover time of 10 samples per hour without technical difficulties. This study reports an effective and valuable protocol for thalassaemia screening in red blood cells which would otherwise be discarded during cord blood processing. Cord blood with severe and intermediate forms of thalassaemia can be preselected and not stored.
  17. Koh KC, Husni S, Tan JE, Tan CW, Kunaseelan S, Nuriah S, et al.
    Med J Malaysia, 2009 Sep;64(3):233-5.
    PMID: 20527275 MyJurnal
    We set out to investigate whether neckties worn by doctors are more likely to be contaminated with Methicillin resistant Staphylococcus aureus (MRSA) compared to neckties worn by preclinical medical undergraduates who have never been exposed to a hospital environment. We discovered that more than half (52%) of neckties worn by doctors were contaminated with Staphylococcus and out of these, 62% of them were identified as MRSA. In contrast, none of the student's ties were contaminated with MRSA. Due to the high prevalence of staphylococcus detected on doctors' neckties, we recommend that health care workers do not wear neckties.
  18. Chong YM, Tan JA, Zubaidah Z, Rahimah A, Kuldip K, George E
    Med J Malaysia, 2006 Jun;61(2):217-20.
    PMID: 16898315
    Thalassaemia is an inherited blood disorder and is a significant public health problem in Malaysia, with many not knowing they carry the gene for thalassaemia. The two major forms are alpha and beta thalassaemia. An individual can co-inherit both the alpha and beta thalassaemia genes. This study determined the frequency of concurrent carriers of alpha thalassaemia in 231 beta thalassaemia carriers. Gap-PCR was done on extracted DNA of the beta thalassaemia samples to check for alpha thalassaemia 1 molecular defect. Eight (3.5%) samples were found to have concurrently inherited the alpha thalassaemia 1 (- -SEA) deletion. The significant carrier rate for alpha thalassaemia 1 indicates the need for the implementation of DNA analysis to complement thalassaemia screening in high risk populations.
  19. Wee YC, Tan KL, Tan PC, Yap SF, Tan JAMA
    Med J Malaysia, 2005 Oct;60(4):447-53.
    PMID: 16570706
    Haemoglobin Bart's hydrops foetalis syndrome (--SEA/--SEA) is not compatible with life and contributes to a majority of the hydropic foetuses in the Malaysian Chinese alpha-thalassaemia carriers who possess the 2-alpha-gene deletion in cis (--SEA/alphaalpha). A duplex-PCR which simultaneously amplifies a normal 136 bp sequence between the psialpha-alpha2-globin genes and a 730 bp Southeast Asian deletion-specific sequence (--SEA) between the psialpha2-theta1-globin genes was established. The duplex-PCR which detects the --SEA deletion in both chromosomes serves as a rapid and cost-effective confirmatory test in the antenatal diagnosis of Haemoglobin Bart's hydrops foetalis syndrome in Malaysia. In addition, the duplex-PCR is simple to perform as both the normal and deletion-specific alpha-globin gene sequences are amplified in the same PCR reaction.
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