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  1. Ong KK, Khor HT, Tan DT
    Anal Biochem, 1991 Aug 01;196(2):211-4.
    PMID: 1776669
    A rapid, easy, and sensitive method is described in this paper for the assay of 3-hydroxy-3-methylglutaryl CoA (HMG CoA) reductase, a key enzyme in cholesterol biosynthesis. [14C]HMG CoA was used as the substrate and the product formed, i.e., [14C]mevalonate, was allowed to be converted to its lactone form (mevalonolactone) in the presence of HCl. The reaction mixture was applied to a column containing an anionic exchanger. The column was made up of QAE-Sephadex (A25, formate form) packed to a height of 4 cm in Pasteur pipets. Under these conditions, mevalonolactone was not retained by the column and was eluted with ammonium formate solution while HMG CoA, being negatively charged, was retained by the gel and eluted by HCl above 0.05 M. Determination of the amount of radioactivity in mevalonolactone was then used to quantitate the activity of HMG CoA reductase. This assay has been successfully used for determining the activity of this enzyme in a microsomal fraction prepared from the liver of the rat.
  2. Allotey P, Tan DT, Kirby T, Tan LH
    Health Syst Reform, 2019;5(1):66-77.
    PMID: 30924744 DOI: 10.1080/23288604.2018.1541497
    Community engagement describes a complex political process with dynamic negotiation and renegotiation of power and authority between providers and recipients of health care in order to achieve a shared goal of universal health care coverage. Though examples exist of community engagement projects, there is very little guidance on how to implement and embed community engagement as a concerted, integrated, strategic, and sustained component of health systems. Through a series of case studies, this article explores the factors that enable community engagement particularly with a direct impact on health systems.
  3. Garg P, Khor WB, Roy A, Tan DT, APAX consortium
    Int Ophthalmol, 2023 Nov;43(11):4151-4162.
    PMID: 37526782 DOI: 10.1007/s10792-023-02816-w
    PURPOSE: To determine current institutional practice patterns for the use of perioperative antibiotics and other measures to prevent infection after cataract surgery in Asia.

    METHODS: An online survey-based study of leading eye institutions in China, Hong Kong, India, Indonesia, Japan, Malaysia, Pakistan, Philippines, Singapore, South Korea, Taiwan, Thailand and Vietnam was conducted. The survey was administered to 26 representative key opinion leaders from prominent tertiary eye institutions that are also national academic teaching institutions in Asia. Survey responses were collated and anonymized during analysis.

    RESULTS: All surveyed institutions used povidone iodine for the preoperative antiseptic preparation of the eye, with notable variations in the concentration of povidone iodine used for conjunctival sac instillation. Preoperative topical antibiotics were prescribed by 61.5% and 69.2% of institutions in low-risk and high-risk cases, respectively. Regarding the use of intra-operative antibiotics, 60.0% and 66.7% of institutions administered intracameral antibiotics in low-risk and high-risk patients, respectively. Postoperative topical antibiotics use patterns were generally very similar in low-risk and high-risk patients. Over half of the institutions (52.2% and 68.0% in low-risk and high-risk patients, respectively) also indicated prolonged postoperative use of topical antibiotics (> 2 weeks). Not all surveyed institutions had established policies/protocols for perioperative antibiotic use in cataract surgery, endophthalmitis surveillance, and/or a monitoring program for emerging antimicrobial resistance.

    CONCLUSION: There are variations in antimicrobial prophylaxis approaches to preoperative, intra-operative and postoperative regimens in cataract surgery in Asia. More evidence-based research is needed to support the development of detailed guidelines for perioperative antibiotic prophylaxis to reduce postoperative infections.

  4. Tan DT, Khor HT, Low WH, Ali A, Gapor A
    Am J Clin Nutr, 1991 04;53(4 Suppl):1027S-1030S.
    PMID: 2012011 DOI: 10.1093/ajcn/53.4.1027S
    The effect of a capsulated palm-oil-vitamin E concentrate (palmvitee) on human serum and lipoprotein lipids was assessed. Each palmvitee capsule contains approximately 18, approximately 42, and approximately 240 mg of tocopherols, tocotrienols, and palm olein, respectively. All volunteers took one palmvitee capsule per day for 30 consecutive days. Overnight fasting blood was taken from each volunteer before and after the experiment. Serum lipids and lipoproteins were analyzed by using the enzymatic CHOD-PAP method. Our results showed that palmvitee lowered both serum total cholesterol (TC) and low-density-lipoprotein cholesterol (LDL-C) concentrations in all the volunteers. The magnitude of reduction of serum TC ranged from 5.0% to 35.9% whereas the reduction of LDL-C values ranged from 0.9% to 37.0% when compared with their respective starting values. The effect of palmvitee on triglycerides (TGs) and HDL-C was not consistent. Our results show that the palmvitee has a hypocholesterolemic effect.
  5. Saw SM, Goh PP, Cheng A, Shankar A, Tan DT, Ellwein LB
    Br J Ophthalmol, 2006 Oct;90(10):1230-5.
    PMID: 16809384
    To compare the prevalences of refractive errors in Malay, Chinese and Indian children in Malaysia and Singapore.
  6. Tan DT, Siri JG, Gong Y, Ong B, Lim SC, MacGillivray BH, et al.
    Global Health, 2019 12 18;15(1):85.
    PMID: 31847865 DOI: 10.1186/s12992-019-0527-1
    BACKGROUND: Localisation is a pervasive challenge in achieving sustainable development. Contextual particularities may render generalized strategies to achieve the Sustainable Development Goals (SDGs) unfeasible, impractical, or ineffective. Furthermore, many localities are resource- and data-poor, limiting applicability of the global SDG indicator framework. Tools to enable local actors to make sense of complex problems, communicate this understanding, and act accordingly hold promise in their ability to improve results.

    AIM: Systems approaches can help characterise local causal systems, identify useful leverage points, and foster participation needed to localise and catalyse development action. Critically, such efforts must be deeply rooted in place, involving local actors in mapping decision-processes and causation within local physical, social and policy environments. Given that each place has a unique geographical or spatial extent and therein lies its unique characters and problems, we term these activities "placially explicit." We describe and reflect on a process used to develop placially explicit, systems-based (PESB) case studies on issues that intersect with and impact urban health and wellbeing, addressing the perspectives of various actors to produce place-based models and insights that are useful for SDG localisation.

    METHODS: Seven case studies were co-produced by one or more Partners with place-based knowledge of the case study issue and a Systems Thinker. In each case, joint delineation of an appropriate framing was followed by iterative dialogue cycles to uncover key contextual factors, with attention to institutional and societal structures and paradigms and the motivations and constraints of other actors. Casual loop diagrams (CLDs) were iteratively developed to capture complex narratives in a simple visual way.

    RESULTS: Case study development facilitated transfer of local knowledge and development of systems thinking capacity. Partners reported new insights, including a shifting of problem frames and corresponding solution spaces to higher systems levels. Such changes led partners to re-evaluate their roles and goals, and thence to new actions and strategies. CLD-based narratives also proved useful in ongoing communications.

    CONCLUSION: Co-production of PESB case studies are a useful component of transdisciplinary toolsets for local SDG implementation, building the capacity of local actors to explore complex problems, identify new solutions and indicators, and understand the systemic linkages inherent in SDG actions across sectors and scales.

  7. Foong AW, Saw SM, Loo JL, Shen S, Loon SC, Rosman M, et al.
    Ophthalmic Epidemiol, 2007 Jan-Feb;14(1):25-35.
    PMID: 17365815
    Although there are approximately 200 million people of Malay ethnicity living in Asia, the burden and risk factors of blinding eye diseases in this ethnic group are unknown. This study summarizes the rationale and study design of a population-based study of eye diseases among adult Malays in Singapore.
  8. Nongpiur ME, Khor CC, Jia H, Cornes BK, Chen LJ, Qiao C, et al.
    PLoS Genet, 2014 Mar;10(3):e1004089.
    PMID: 24603532 DOI: 10.1371/journal.pgen.1004089
    Anterior chamber depth (ACD) is a key anatomical risk factor for primary angle closure glaucoma (PACG). We conducted a genome-wide association study (GWAS) on ACD to discover novel genes for PACG on a total of 5,308 population-based individuals of Asian descent. Genome-wide significant association was observed at a sequence variant within ABCC5 (rs1401999; per-allele effect size =  -0.045 mm, P = 8.17 × 10(-9)). This locus was associated with an increase in risk of PACG in a separate case-control study of 4,276 PACG cases and 18,801 controls (per-allele OR = 1.13 [95% CI: 1.06-1.22], P = 0.00046). The association was strengthened when a sub-group of controls with open angles were included in the analysis (per-allele OR = 1.30, P = 7.45 × 10(-9); 3,458 cases vs. 3,831 controls). Our findings suggest that the increase in PACG risk could in part be mediated by genetic sequence variants influencing anterior chamber dimensions.
  9. Vithana EN, Khor CC, Qiao C, Nongpiur ME, George R, Chen LJ, et al.
    Nat Genet, 2012 Oct;44(10):1142-1146.
    PMID: 22922875 DOI: 10.1038/ng.2390
    Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study including 1,854 PACG cases and 9,608 controls across 5 sample collections in Asia. Replication experiments were conducted in 1,917 PACG cases and 8,943 controls collected from a further 6 sample collections. We report significant associations at three new loci: rs11024102 in PLEKHA7 (per-allele odds ratio (OR)=1.22; P=5.33×10(-12)), rs3753841 in COL11A1 (per-allele OR=1.20; P=9.22×10(-10)) and rs1015213 located between PCMTD1 and ST18 on chromosome 8q (per-allele OR=1.50; P=3.29×10(-9)). Our findings, accumulated across these independent worldwide collections, suggest possible mechanisms explaining the pathogenesis of PACG.
  10. Khor CC, Do T, Jia H, Nakano M, George R, Abu-Amero K, et al.
    Nat Genet, 2016 May;48(5):556-62.
    PMID: 27064256 DOI: 10.1038/ng.3540
    Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study (GWAS) followed by replication in a combined total of 10,503 PACG cases and 29,567 controls drawn from 24 countries across Asia, Australia, Europe, North America, and South America. We observed significant evidence of disease association at five new genetic loci upon meta-analysis of all patient collections. These loci are at EPDR1 rs3816415 (odds ratio (OR) = 1.24, P = 5.94 × 10(-15)), CHAT rs1258267 (OR = 1.22, P = 2.85 × 10(-16)), GLIS3 rs736893 (OR = 1.18, P = 1.43 × 10(-14)), FERMT2 rs7494379 (OR = 1.14, P = 3.43 × 10(-11)), and DPM2-FAM102A rs3739821 (OR = 1.15, P = 8.32 × 10(-12)). We also confirmed significant association at three previously described loci (P < 5 × 10(-8) for each sentinel SNP at PLEKHA7, COL11A1, and PCMTD1-ST18), providing new insights into the biology of PACG.
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