Displaying publications 41 - 60 of 92 in total

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  1. Tan SH, Mohd Aris E, Kurahashi H, Mohamed Z
    Trop Biomed, 2010 Aug;27(2):287-93.
    PMID: 20962727
    Iranihindia martellata (Senior-White, 1924) is recorded from peninsular Malaysia for the first time. Male and female specimens in the recent collections of forensically important sarcophagid flies were examined and identified based on morphology and DNA sequencing analysis. Male genitalia offer unambiguous species identification characteristics in the traditional taxonomy of flesh flies but the female flies are very similar to one another in general morphology. Female of I. martellata was determined by DNA sequencing (COI and COII) and PCR-RFLP (COI) analysis. Identified females were carefully examined and compared with the morphologically similar species, Liopygia ruficornis (Fabricius, 1794). Female genitalia are re-described and illustrated in this paper.
  2. Tan SH, Aris EM, Surin J, Omar B, Kurahashi H, Mohamed Z
    Trop Biomed, 2009 Aug;26(2):173-81.
    PMID: 19901904
    The mitochondiral DNA region encompassing the cytochrome oxidase subunit I (COI) and cytochrome oxidase subunit II (COII) genes of two Malaysian blow fly species, Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart) were studied. This region, which spans 2303bp and includes the COI, tRNA leucine and partial COII was sequenced from adult fly and larval specimens, and compared. Intraspecific variations were observed at 0.26% for Ch. megacephala and 0.17% for Ch. rufifacies, while sequence divergence between the two species was recorded at a minimum of 141 out of 2303 sites (6.12%). Results obtained in this study are comparable to published data, and thus support the use of DNA sequence to facilitate and complement morphology-based species identification.
  3. Au SL, Tan SH, Harikrishna K, Napis S
    J. Biochem. Mol. Biol. Biophys., 2002 Oct;6(5):301-8.
    PMID: 12385964
    Four ADP-glucose pyrophosphorylase cDNA clones were isolated from mature leaves and pith of sago palm by the polymerase chain reaction (PCR) technique. Three of them (agpp10, agpp12 and agpl19) encoded the AGP large subunit, while the fourth clone (agpl1) encoded the small subunit. agpp10 and agpp12 were isolated from pith, agpl19 was isolated from mature leaves, while agpl1 from both tissues. In addition, a full-length cDNA of agpl1 was successfully isolated from a cDNA library of mature leaves by a PCR-based screening technique. Semi-quantitative analysis suggests that agpp10 and agpp12 were detectable only in pith, agpl19 only in leaves, while agpl1 was expressed in both leaves and pith tissues.
  4. Lau ET, Tan SH, Antwertinger YJ, Hall T, Nissen LM
    J Pain Res, 2019;12:2441-2455.
    PMID: 31496787 DOI: 10.2147/JPR.S199017
    Background: People living with persistent pain in Australia often cannot access adequate care to manage their pain. Therefore, as the most accessible healthcare professionals, community pharmacists have an important role to play in helping to improve patient outcomes. Hence, it is important to investigate patient needs and expectations in terms of counseling interactions with pharmacists, along with pharmacists' approach to counseling interactions with these patients.

    Method: The nature of patient-pharmacist counseling interactions was explored with seven patients (one focus group), and 10 practicing pharmacists (two focus groups, three semi-structured interviews). The themes identified informed the development of an online survey that was advertised online to patients and pharmacists across Australia.

    Results: A total of 95 patients and 208 pharmacists completed the survey. Overall, more than half of patients (77/95) were satisfied with the care provided by their pharmacist, but only a third (71/205) of pharmacists were satisfied with the care they provided to patients. The majority of patients (67/94) reported that pharmacists provided good information about medications. This aligned with pharmacists' responses, as most reported focusing on medication side effects (118/188) and instructions for taking pain medication (93/183) during patient interactions. However, when asked about empathy and rapport from pharmacists, only half to two-thirds (48-61/95) of patients expressed positive views. Overall, half of the patients (39/75) wanted a caring, empathetic, respectful, and private conversation with the pharmacist, and nearly half (40/89) perceived the pharmacist's role as providing (new) information on alternative pharmacological and non-pharmacological therapies, including general advice on pain management.

    Conclusion: There was a disparity in the nature of the interaction and information that patients wanted from pharmacists, compared to what was provided by pharmacists. Training and education may help pharmacists to better engage in patient-centered care when interacting with people living with persistent pain, thereby improving health outcomes for these patients.

  5. Ang WX, Sarasvathy S, Kuppusamy UR, Sabaratnam V, Tan SH, Wong KT, et al.
    Trop Biomed, 2021 Sep 01;38(3):239-247.
    PMID: 34362866 DOI: 10.47665/tb.38.3.063
    Hand, foot and mouth disease (HFMD) is a highly contagious viral disease that predominantly affects children younger than 5 years old. HFMD is primarily caused by enterovirus A71 (EVA71) and coxsackievirus A16 (CV-A16). However, coxsackievirus A10 (CV-A10) and coxsackievirus A6 (CV-A6) are being increasingly reported as the predominant causative of HFMD outbreaks worldwide since the past decade. To date, there are still no licensed multivalent vaccines or antiviral drugs targeting enteroviruses that cause HFMD, despite HFMD outbreaks are still being frequently reported, especially in Asia-Pacific countries. The high rate of transmission, morbidity and potential neurological complications of HFMD is indeed making the development of broad-spectrum antiviral drugs/agents against these enteroviruses a compelling need. In this study, we have investigated the in vitro antiviral effect of 4 Ganoderma neo-japonicum Imazeki (GNJI) crude extracts (S1-S4) against EV-A71, CV-A16, CV-A10 and CV-A6. GNJI is a medicinal mushroom that can be found growing saprophytically on decaying bamboo clumps in Malaysian forests. The antiviral effects of this medicinal mushroom were determined using cytopathic inhibition and virus titration assays. The S2 (1.25 mg/ml) hot aqueous extract demonstrated the highest broad-spectrum antiviral activity against all tested enteroviruses in human primary oral fibroblast cells. Replication of EV-A71, CV-A16 and CVA10 were effectively inhibited at 2 hours post-infection (hpi) to 72 hpi, except for CV-A6 which was only at 2 hpi. S2 also has virucidal activity against EV-A71. Polysaccharides isolated and purified from crude hot aqueous extract demonstrated similar antiviral activity as S2, suggesting that polysaccharides could be one of the active compounds responsible for the antiviral activity shown by S2. To our knowledge, this study demonstrates for the first time the ability of GNJI to inhibit enterovirus infection and replication. Thus, GNJI is potential to be further developed as an antiviral agent against enteroviruses that caused HFMD.
  6. Yee PTI, Tan SH, Ong KC, Tan KO, Wong KT, Hassan SS, et al.
    Sci Rep, 2019 03 18;9(1):4805.
    PMID: 30886246 DOI: 10.1038/s41598-019-41285-z
    Besides causing mild hand, foot and mouth infections, Enterovirus A71 (EV-A71) is associated with neurological complications and fatality. With concerns about rising EV-A71 virulence, there is an urgency for more effective vaccines. The live attenuated vaccine (LAV) is a more valuable vaccine as it can elicit both humoral and cellular immune responses. A miRNA-based vaccine strain (pIY) carrying let-7a and miR-124a target genes in the EV-A71 genome which has a partial deletion in the 5'NTR (∆11 bp) and G64R mutation (3Dp°l) was designed. The viral RNA copy number and viral titers of the pIY strain were significantly lower in SHSY-5Y cells that expressed both let-7a and miR-124a. Inhibition of the cognate miRNAs expressed in RD and SHSY-5Y cells demonstrated de-repression of viral mRNA translation. A previously constructed multiply mutated strain, MMS and the pIY vaccine strain were assessed in their ability to protect 4-week old mice from hind limb paralysis. The MMS showed higher amounts of IFN-γ ex vivo than the pIY vaccine strain. There was absence of EV-A71 antigen in the skeletal muscles and spinal cord micrographs of mice vaccinated with the MMS and pIY strains. The MMS and pIY strains are promising LAV candidates developed against severe EV-A71 infections.
  7. Lalani S, Tan SH, Tan KO, Lim HX, Ong KC, Wong KT, et al.
    Life Sci, 2021 Dec 15;287:120097.
    PMID: 34715144 DOI: 10.1016/j.lfs.2021.120097
    AIMS: Enterovirus A71 (EV-A71) is an etiological agent of hand foot and mouth disease (HFMD) and has the potential to cause severe neurological infections in children. L-SP40 peptide was previously known to inhibit EV-A71 by prophylactic action. This study aimed to identify the mechanism of inhibition in Rhabdomyosarcoma (RD) cells and in vivo therapeutic potential of L-SP40 peptide in a murine model.

    MAIN METHODS: A pull-down assay was performed to identify the binding partner of the L-SP40 peptide. Co-immunoprecipitation and co-localization assays with the L-SP40 peptide were employed to confirm the receptor partner in RD cells. The outcomes were validated using receptor knockdown and antibody blocking assays. The L-SP40 peptide was further evaluated for the protection of neonatal mice against lethal challenge by mouse-adapted EV-A71.

    KEY FINDINGS: The L-SP40 peptide was found to interact and co-localize with nucleolin, the key attachment receptor of Enteroviruses A species, as demonstrated in the pull-down, co-immunoprecipitation and co-localization assays. Knockdown of nucleolin from RD cells led to a significant reduction of 3.5 logs of viral titer of EV-A71. The L-SP40 peptide demonstrated 80% protection of neonatal mice against lethal challenge by the mouse-adapted virus with a drastic reduction in the viral loads in the blood (~4.5 logs), skeletal muscles (1.5 logs) and brain stem (1.5 logs).

    SIGNIFICANCE: L-SP40 peptide prevented severe hind limb paralysis and death in suckling mice and could serve as a potential broad-spectrum antiviral candidate to be further evaluated for safety and potency in future clinical trials against EV-A71.

  8. Khalid K, Lim HX, Anwar A, Tan SH, Hwang JS, Ong SK, et al.
    AAPS PharmSciTech, 2024 Mar 12;25(3):60.
    PMID: 38472523 DOI: 10.1208/s12249-024-02778-x
    The protective efficacies of current licensed vaccines against COVID-19 have significantly reduced as a result of SARS-CoV-2 variants of concern (VOCs) which carried multiple mutations in the Spike (S) protein. Considering that these vaccines were developed based on the S protein of the original SARS-CoV-2 Wuhan strain, we designed a recombinant plasmid DNA vaccine based on highly conserved and immunogenic B and T cell epitopes against SARS-CoV-2 Wuhan strain and the Omicron VOC. Literature mining and bioinformatics were used to identify 6 immunogenic peptides from conserved regions of the SARS-CoV-2 S and membrane (M) proteins. Nucleotide sequences encoding these peptides representing highly conserved B and T cell epitopes were cloned into a pVAX1 vector to form the pVAX1/S2-6EHGFP recombinant DNA plasmid vaccine. The DNA vaccine was intranasally or intramuscularly administered to BALB/c mice and evaluations of humoral and cellular immune responses were performed. The intramuscular administration of pVAX1/S2-6EHGFP was associated with a significantly higher percentage of CD8+ T cells expressing IFN-γ when compared with the empty vector and PBS controls. Intramuscular or intranasal administrations of pVAX1/S2-6EHGFP resulted in robust IgG antibody responses. Sera from mice intramuscularly immunized with pVAX1/S2-6EHGFP were found to elicit neutralizing antibodies capable of SARS-CoV-2 Omicron variant with the ACE2 cell surface receptor. This study demonstrated that the DNA vaccine construct encoding highly conserved immunogenic B and T cell epitopes was capable of eliciting potent humoral and cellular immune responses in mice.
  9. Tan SH, Chong AW, Nazarina AR, Prepageran N
    Otolaryngol Pol, 2014 Sep-Oct;68(5):268-70.
    PMID: 25283325 DOI: 10.1016/j.otpol.2013.09.003
    We describe a rare case of BSCC in the retromolar trigone with only 3 other cases in the literature and also compare the differences between 2 cases of BSCC in terms of presentation and progression. The first patient had a markedly slower progression with painful retromolar trigone swelling over 4 months without nodal metastases. In contrast, the second patient gave a 2-week history of neck swelling with nodal involvement, indicating extremely rapid progression. Our management was tailored accordingly with the first patient undergoing intraoral excision of tumour and adjuvant radiotherapy while the other had bilateral neck dissection with postoperative chemoradiotherapy. Both patients achieved good outcome and are free from disease.
  10. Tan SH, Chong AW, Prepageran N
    Iran J Otorhinolaryngol, 2015 Sep;27(82):391-4.
    PMID: 26568944
    INTRODUCTION: Atypical infratemporal fossa infections are rare and potentially fatal.

    CASE REPORT: A case of an aspergillosis localized in the infratemporal fossa and another case of tuberculosis of the infratemporal fossa originating from the maxillary sinus, is described. The first patient was immunocompromised and showed symptoms of facial numbness; whereas the other was an immunocompetent man who complained of trigeminal neuralgia type pain. It was difficult to differentiate between infection and tumour despite the utilization of computed tomography scans and magnetic resonance imaging.

    CONCLUSION: These cases illustrate the need for a high index of suspicion; in addition to endoscopic confirmation and histopathology to establish precise diagnosis and early intervention.

  11. Tan SH, Prepageran N
    J Laryngol Otol, 2015 Sep;129(9):928-31.
    PMID: 26193981 DOI: 10.1017/S0022215115001838
    This case report presents our experience of endoscopic transnasal management of medial intra- and extraconal lesions.
  12. Tan SH, Balachandran R, Prepageran N
    Eur J Intern Med, 2019 02;60:e3-e4.
    PMID: 29759815 DOI: 10.1016/j.ejim.2018.05.012
  13. Tan SH, Prepageran N
    QJM, 2018 Oct 01;111(10):743.
    PMID: 29660085 DOI: 10.1093/qjmed/hcy084
  14. Tan SH, Kulasegarah J, Prepageran N
    Indian J Otolaryngol Head Neck Surg, 2023 Apr;75(Suppl 1):416-418.
    PMID: 36777926 DOI: 10.1007/s12070-023-03505-x
    We report the first case series utilizing the exoscope exclusively for bilateral simultaneous cochlear implant surgery and discuss the advantages, disadvantages, as well as surgical outcomes in the Covid-19 era. The VITOM® 2D is compatible with enhanced PPE and draping techniques which can improve safety while providing comparable surgical outcomes.
  15. Tan SH, Normi YM, Leow AT, Salleh AB, Murad AM, Mahadi NM, et al.
    J. Biochem., 2017 02 01;161(2):167-186.
    PMID: 28175318 DOI: 10.1093/jb/mvw058
    The effectiveness of β-lactam antibiotics as chemotherapeutic agents to treat bacterial infections is gradually threatened with the emergence of antibiotic resistance mechanism among pathogenic bacteria through the production metallo-β-lactamase (MBL). In this study, we discovered a novel hypothetical protein (HP) termed Bleg1_2437 from the genome of alkaliphilic Bacillus lehensis G1 which exhibited MBL-like properties of B3 subclass; but evolutionary divergent from other circulating B3 MBLs. Domain and sequence analysis of HP Bleg1_2437 revealed that it contains highly conserved Zn2+-binding residues such as H54, H56, D58, H59, H131 and H191, important for catalysis, similar with the subclass B3 of MBL. Built 3-D Bleg1_2437 structure exhibited an αββα sandwich layer similar to the well-conserved global topology of MBL superfamily. Other features include a ceiling and floor in the model which are important for accommodation and orientation of β-lactam antibiotics docked to the protein model showed interactions at varying degrees with residues in the binding pocket of Bleg1_2437. Hydrolysis activity towards several β-lactam antibiotics was proven through an in vitro assay using purified recombinant Bleg1_2437 protein. These findings highlight the presence of a clinically important and evolutionary divergent antibiotics-degrading enzyme within the pools of uncharacterized HPs.
  16. Tan SH, Normi YM, Leow AT, Salleh AB, Karjiban RA, Murad AM, et al.
    BMC Struct Biol, 2014 Mar 19;14:11.
    PMID: 24641837 DOI: 10.1186/1472-6807-14-11
    BACKGROUND: At least a quarter of any complete genome encodes for hypothetical proteins (HPs) which are largely non-similar to other known, well-characterized proteins. Predicting and solving their structures and functions is imperative to aid understanding of any given organism as a complete biological system. The present study highlights the primary effort to classify and cluster 1202 HPs of Bacillus lehensis G1 alkaliphile to serve as a platform to mine and select specific HP(s) to be studied further in greater detail.

    RESULTS: All HPs of B. lehensis G1 were grouped according to their predicted functions based on the presence of functional domains in their sequences. From the metal-binding group of HPs of the cluster, an HP termed Bleg1_2507 was discovered to contain a thioredoxin (Trx) domain and highly-conserved metal-binding ligands represented by Cys69, Cys73 and His159, similar to all prokaryotic and eukaryotic Sco proteins. The built 3D structure of Bleg1_2507 showed that it shared the βαβαββ core structure of Trx-like proteins as well as three flanking β-sheets, a 310 -helix at the N-terminus and a hairpin structure unique to Sco proteins. Docking simulations provided an interesting view of Bleg1_2507 in association with its putative cytochrome c oxidase subunit II (COXII) redox partner, Bleg1_2337, where the latter can be seen to hold its partner in an embrace, facilitated by hydrophobic and ionic interactions between the proteins. Although Bleg1_2507 shares relatively low sequence identity (47%) to BsSco, interestingly, the predicted metal-binding residues of Bleg1_2507 i.e. Cys-69, Cys-73 and His-159 were located at flexible active loops similar to other Sco proteins across biological taxa. This highlights structural conservation of Sco despite their various functions in prokaryotes and eukaryotes.

    CONCLUSIONS: We propose that HP Bleg1_2507 is a Sco protein which is able to interact with COXII, its redox partner and therefore, may possess metallochaperone and redox functions similar to other documented bacterial Sco proteins. It is hoped that this scientific effort will help to spur the search for other physiologically relevant proteins among the so-called "orphan" proteins of any given organism.

  17. Murugan AC, Karim MR, Yusoff MB, Tan SH, Asras MF, Rashid SS
    Pharm Biol, 2015 Aug;53(8):1087-97.
    PMID: 25630358 DOI: 10.3109/13880209.2014.959615
    CONTEXT: Polyphenol-rich marine macroalgae are gaining dietary importance due to their influence over diabetes mellitus and the role as a vital source of high-value nutraceuticals. Their assorted beneficial effects on human health include competitive inhibition of digestive enzymes, varying the activity of hepatic glucose-metabolizing enzymes, lowering the plasma glucose levels, and lipid peroxidation, delaying the aging process.

    OBJECTIVE: In this paper, we review the health beneficial effects of polyphenols and phlorotannins from brown seaweeds with special emphasis on their inhibitory effects on carbohydrate-metabolizing enzymes.

    METHODS: A survey of literature from databases such as Sciencedirect, Scopus, Pubmed, Springerlink, and Google Scholar from the year 1973 to 2013 was done to bring together the information relating to drug discovery from brown seaweeds as a source for diabetes treatment.

    RESULTS: Over the past two decades, 20 different bioactive polyphenols/phlorotannins have been isolated and studied from 10 different brown algae. Discussion of the positive effect on the inhibition of enzymes metabolizing carbohydrates in both in vitro and in vivo experiments are included.

    CONCLUSION: Despite the recent advancements in isolating bioactive compounds from seaweeds with potential health benefit or pharmaceutical behavior, studies on the polyphenol effectiveness on glucose homeostasis in human beings are very few in response to their functional characterization. Added research in this area is required to confirm the close connection of polyphenol rich seaweed-based diet consumption with glucose homeostasis and the exciting possibility of prescribing polyphenols to treat the diabetes pandemic.

  18. Chan MY, Efthymios M, Tan SH, Pickering JW, Troughton R, Pemberton C, et al.
    Circulation, 2020 10 13;142(15):1408-1421.
    PMID: 32885678 DOI: 10.1161/CIRCULATIONAHA.119.045158
    BACKGROUND: Heart failure (HF) is the most common long-term complication of acute myocardial infarction (MI). Understanding plasma proteins associated with post-MI HF and their gene expression may identify new candidates for biomarker and drug target discovery.

    METHODS: We used aptamer-based affinity-capture plasma proteomics to measure 1305 plasma proteins at 1 month post-MI in a New Zealand cohort (CDCS [Coronary Disease Cohort Study]) including 181 patients post-MI who were subsequently hospitalized for HF in comparison with 250 patients post-MI who remained event free over a median follow-up of 4.9 years. We then correlated plasma proteins with left ventricular ejection fraction measured at 4 months post-MI and identified proteins potentially coregulated in post-MI HF using weighted gene co-expression network analysis. A Singapore cohort (IMMACULATE [Improving Outcomes in Myocardial Infarction through Reversal of Cardiac Remodelling]) of 223 patients post-MI, of which 33 patients were hospitalized for HF (median follow-up, 2.0 years), was used for further candidate enrichment of plasma proteins by using Fisher meta-analysis, resampling-based statistical testing, and machine learning. We then cross-referenced differentially expressed proteins with their differentially expressed genes from single-cell transcriptomes of nonmyocyte cardiac cells isolated from a murine MI model, and single-cell and single-nucleus transcriptomes of cardiac myocytes from murine HF models and human patients with HF.

    RESULTS: In the CDCS cohort, 212 differentially expressed plasma proteins were significantly associated with subsequent HF events. Of these, 96 correlated with left ventricular ejection fraction measured at 4 months post-MI. Weighted gene co-expression network analysis prioritized 63 of the 212 proteins that demonstrated significantly higher correlations among patients who developed post-MI HF in comparison with event-free controls (data set 1). Cross-cohort meta-analysis of the IMMACULATE cohort identified 36 plasma proteins associated with post-MI HF (data set 2), whereas single-cell transcriptomes identified 15 gene-protein candidates (data set 3). The majority of prioritized proteins were of matricellular origin. The 6 most highly enriched proteins that were common to all 3 data sets included well-established biomarkers of post-MI HF: N-terminal B-type natriuretic peptide and troponin T, and newly emergent biomarkers, angiopoietin-2, thrombospondin-2, latent transforming growth factor-β binding protein-4, and follistatin-related protein-3, as well.

    CONCLUSIONS: Large-scale human plasma proteomics, cross-referenced to unbiased cardiac transcriptomics at single-cell resolution, prioritized protein candidates associated with post-MI HF for further mechanistic and clinical validation.

  19. Mangano MC, Berlino M, Corbari L, Milisenda G, Lucchese M, Terzo S, et al.
    Environ Sci Policy, 2022 Jan;127:98-110.
    PMID: 34720746 DOI: 10.1016/j.envsci.2021.10.014
    The COVID-19 global pandemic has had severe, unpredictable and synchronous impacts on all levels of perishable food supply chains (PFSC), across multiple sectors and spatial scales. Aquaculture plays a vital and rapidly expanding role in food security, in some cases overtaking wild caught fisheries in the production of high-quality animal protein in this PFSC. We performed a rapid global assessment to evaluate the effects of the COVID-19 pandemic and related emerging control measures on the aquaculture supply chain. Socio-economic effects of the pandemic were analysed by surveying the perceptions of stakeholders, who were asked to describe potential supply-side disruption, vulnerabilities and resilience patterns along the production pipeline with four main supply chain components: a) hatchery, b) production/processing, c) distribution/logistics and d) market. We also assessed different farming strategies, comparing land- vs. sea-based systems; extensive vs. intensive methods; and with and without integrated multi-trophic aquaculture, IMTA. In addition to evaluating levels and sources of economic distress, interviewees were asked to identify mitigation solutions adopted at local / internal (i.e., farm-site) scales, and to express their preference on national / external scale mitigation measures among a set of a priori options. Survey responses identified the potential causes of disruption, ripple effects, sources of food insecurity, and socio-economic conflicts. They also pointed to various levels of mitigation strategies. The collated evidence represents a first baseline useful to address future disaster-driven responses, to reinforce the resilience of the sector and to facilitate the design reconstruction plans and mitigation measures, such as financial aid strategies.
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