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  1. Lim CT, Chew CT, Chew SH
    Ann Acad Med Singap, 1992 May;21(3):399-403.
    PMID: 1416791
    Most muscular dystrophies manifest as peripheral muscular weakness commencing at various age, however, oculopharyngeal muscular dystrophy (OPMD) is a rare hereditary disorder presenting in middle age with progressive dysphagia and bilateral blepharoptosis rather than peripheral muscular weakness. In the medical literature, OPMD has been well described in Canadians of French descent. So far, there is no publication of OPMD in the Malaysia-Singapore medical literature. This article documents this condition in a Chinese patient. A review of the literature is presented and the management of OPMD is discussed.
  2. Wu HT, Lin YT, Chew SH, Wu KJ
    Biomed J, 2023 Feb;46(1):122-133.
    PMID: 35183794 DOI: 10.1016/j.bj.2022.02.002
    BACKGROUND: K63-linked polyubiquitination of proteins have nonproteolytic functions and regulate the activity of many signal transduction pathways. USP7, a HIF1α deubiquitinase, undergoes K63-linked polyubiquitination under hypoxia. K63-polyubiquitinated USP7 serves as a scaffold to anchor HIF1α, CREBBP, the mediator complex, and the super elongation complex to enhance HIF1α-induced gene transcription. However, the physiological role of K63-polyubiquitinated USP7 remains unknown.

    METHODS: Using a Usp7K444R point mutation knock-in mouse strain, we performed immunohistochemistry and standard molecular biological methods to examine the organ defects of liver and kidney in this knock-in mouse strain. Mechanistic studies were performed by using deubiquitination, immunoprecipitation, and quantitative immunoprecipitations (qChIP) assays.

    RESULTS: We observed multiple organ defects, including decreased liver and muscle weight, decreased tibia/fibula length, liver glycogen storage defect, and polycystic kidneys. The underlying mechanisms include the regulation of protein stability and/or modulation of transcriptional activation of several key factors, leading to decreased protein levels of Prr5l, Hnf4α, Cebpα, and Hnf1β. Repression of these crucial factors leads to the organ defects described above.

    CONCLUSIONS: K63-polyubiquitinated Usp7 plays an essential role in the development of multiple organs and illustrates the importance of the process of K63-linked polyubiquitination in regulating critical protein functions.

  3. Chew SH, Looi I, Neoh KK, Ooi J, Cheah WK, Zariah AA
    Med J Malaysia, 2021 Jan;76(1):12-16.
    PMID: 33510102
    BACKGROUND: Thrombolytic therapy with intravenous alteplase is a well-established treatment for acute ischaemic stroke (AIS). However, in Malaysia, treatment prescription is often limited by the availability of neurologists. The objective was to compare the outcomes of acute stroke thrombolysis therapy prescribed by neurologists in the Seberang Jaya Hospital (SJH) and non-neurologists in the Taiping Hospital (TH).

    METHODS: In this cross-sectional study, all AIS patients who received thrombolytic therapy in SJH and TH between January 2012 and September 2019 were included. Clinical data was extracted from admission records. The outcomes assessed were the percentage of patients who achieved excellent functional outcome at 3 months (modified Rankin scale of 0 to 1), rates of symptomatic intracranial haemorrhage (SICH), and mortality.

    RESULTS: A total of 63 AIS patients who received thrombolytic therapy were included, of which 37 patients (58.7%) were treated in SJH. The median NIHSS on admission was 12 in SJH and 11.5 in TH. In all 21.6% of patients from SJH and 30.7% of patients from TH achieved favourable functional outcome at 3 months (p=0.412). There were no significant differences between the two centres in terms of the rates of SICH (10.8% in SJH and 3.8% in TH, p=0.314) and 3-month mortality (24.3% versus 12.5%, p=0.203).

    CONCLUSION: The 3-month functional outcomes and complication rates of stroke thrombolysis in hospitals with or without neurologists are not significantly different. Thus non-neurologist hospitals may be able to provide thrombolysis service to AIS patients safely and effectively.

  4. Chew SH, Achmad Sankala HB, Chew E, Md Arif MHB, Mohd Zain NR, Hashim H, et al.
    Mult Scler Relat Disord, 2023 Nov;79:104992.
    PMID: 37717306 DOI: 10.1016/j.msard.2023.104992
    BACKGROUND: Differentiating tumefactive demyelinating lesions (TDL) from neoplasms of the central nervous system continues to be a diagnostic dilemma in many cases.

    OBJECTIVE: Our study aimed to examine and contrast the clinical and radiological characteristics of TDL, high-grade gliomas (HGG) and primary CNS lymphoma (CNSL).

    METHOD: This was a retrospective review of 66 patients (23 TDL, 31 HGG and 12 CNSL). Clinical and laboratory data were obtained. MRI brain at presentation were analyzed by two independent, blinded neuroradiologists.

    RESULTS: Patients with TDLs were younger and predominantly female. Sensorimotor deficits and ataxia were more common amongst TDL whereas headaches and altered mental status were associated with HGG and CNSL. Compared to HGG and CNSL, MRI characteristics supporting TDL included relatively smaller size, lack of or mild mass effect, incomplete peripheral rim enhancement, absence of central enhancement or restricted diffusion, lack of cortical involvement, and presence of remote white matter lesions on the index scan. Paradoxically, some TDLs may present atypically or radiologically mimic CNS lymphomas.

    CONCLUSION: Careful evaluation of clinical and radiological features helps in differentiating TDLs at first presentation from CNS neoplasms.

  5. Schee JP, Ang CL, Crystal Teoh SC, Tan HJ, Chew SH, Steven A, et al.
    Med J Malaysia, 2023 Sep;78(5):594-601.
    PMID: 37775485
    INTRODUCTION: Intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator is beneficial in acute ischaemic stroke (AIS). We aim to compare the realworld clinical outcomes and service efficiency of IVT in Malaysian primary stroke centres (PSCs) versus acute stroke ready hospitals (ASRHs).

    MATERIALS AND METHODS: We conducted a multi-centre cohort study involving 5 PSCs and 7 ASRHs in Malaysia. Through review of medical records of AIS patients who received IVT from 01 January 2014 to 30 June 2021, real-world data was extracted for analysis. Univariate and multivariate regression models were employed to evaluate the role of PSCs versus ASRHs in post-IVT outcomes and complications. Statistical significance was set at p<0.05.

    RESULTS: A total of 313 multi-ethnic Asians, namely 231 from PSCs and 82 from ASRHs, were included. Both groups were comparable in baseline demographic, clinical, and stroke characteristics. The efficiency of IVT delivery (door-toneedle time), functional outcomes (mRS at 3 months post- IVT), and rates of adverse events (intracranial haemorrhages and mortality) following IVT were comparable between the 2 groups. Notably, 46.8% and 48.8% of patients in PSCs and ASRHs group respectively (p=0.752) achieved favourable functional outcome (mRS≤1 at 3 months post-IVT). Regression analyses demonstrated that post-IVT functional outcomes and adverse events were independent of the role of PSCs or ASRHs.

    CONCLUSION: Our study provides real-world evidence which suggests that IVT can be equally safe, effective, and efficiently delivered in ASRHs. This may encourage the establishment of more ASRHs to extend the benefits of IVT to a greater proportion of stroke populations and enhance the regional stroke care.

  6. Li Z, Xia Y, Feng LN, Chen JR, Li HM, Cui J, et al.
    Lancet Oncol, 2016 Sep;17(9):1240-7.
    PMID: 27470079 DOI: 10.1016/S1470-2045(16)30148-6
    BACKGROUND: Extranodal natural killer T-cell lymphoma (NKTCL), nasal type, is a rare and aggressive malignancy that occurs predominantly in Asian and Latin American populations. Although Epstein-Barr virus infection is a known risk factor, other risk factors and the pathogenesis of NKTCL are not well understood. We aimed to identify common genetic variants affecting individual risk of NKTCL.

    METHODS: We did a genome-wide association study of 189 patients with extranodal NKTCL, nasal type (WHO classification criteria; cases) and 957 controls from Guangdong province, southern China. We validated our findings in four independent case-control series, including 75 cases from Guangdong province and 296 controls from Hong Kong, 65 cases and 983 controls from Guangdong province, 125 cases and 1110 controls from Beijing (northern China), and 60 cases and 2476 controls from Singapore. We used imputation and conditional logistic regression analyses to fine-map the associations. We also did a meta-analysis of the replication series and of the entire dataset.

    FINDINGS: Associations exceeding the genome-wide significance threshold (p<5 × 10(-8)) were seen at 51 single-nucleotide polymorphisms (SNPs) mapping to the class II MHC region on chromosome 6, with rs9277378 (located in HLA-DPB1) having the strongest association with NKTCL susceptibility (p=4·21 × 10(-19), odds ratio [OR] 1·84 [95% CI 1·61-2·11] in meta-analysis of entire dataset). Imputation-based fine-mapping across the class II MHC region suggests that four aminoacid residues (Gly84-Gly85-Pro86-Met87) in near-complete linkage disequilibrium at the edge of the peptide-binding groove of HLA-DPB1 could account for most of the association between the rs9277378*A risk allele and NKTCL susceptibility (OR 2·38, p value for haplotype 2·32 × 10(-14)). This association is distinct from MHC associations with Epstein-Barr virus infection.

    INTERPRETATION: To our knowledge, this is the first time that a genetic variant conferring an NKTCL risk is noted at genome-wide significance. This finding underlines the importance of HLA-DP antigen presentation in the pathogenesis of NKTCL.

    FUNDING: Top-Notch Young Talents Program of China, Special Support Program of Guangdong, Specialized Research Fund for the Doctoral Program of Higher Education (20110171120099), Program for New Century Excellent Talents in University (NCET-11-0529), National Medical Research Council of Singapore (TCR12DEC005), Tanoto Foundation Professorship in Medical Oncology, New Century Foundation Limited, Ling Foundation, Singapore National Cancer Centre Research Fund, and the US National Institutes of Health (1R01AR062886, 5U01GM092691-04, and 1R01AR063759-01A1).

  7. 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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