Displaying publications 21 - 36 of 36 in total

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  1. Do TN, Khyasudeen MF, Nowakowski PJ, Zhang Z, Tan HS
    Chem Asian J, 2019 Nov 18;14(22):3992-4000.
    PMID: 31595651 DOI: 10.1002/asia.201900994
    The frequency fluctuation correlation function (FFCF) measures the spectral diffusion of a state's transition while the frequency fluctuation cross-correlation function (FXCF) measures the correlation dynamics between the transitions of two separate states. These quantities contain a wealth of information on how the chromophores or excitonic states interact and couple with its environment and with each other. We summarize the experimental implementations and theoretical considerations of using two-dimensional electronic spectroscopy to characterize FFCFs and FXCFs. Applications can be found in systems such as the chlorophyll pigment molecules in light-harvesting complexes and CdSe nanomaterials.
  2. Tan HS, Jacoby RP, Ong-Abdullah M, Taylor NL, Liddell S, Chee WW, et al.
    Electrophoresis, 2017 04;38(8):1147-1153.
    PMID: 28198080 DOI: 10.1002/elps.201600506
    Oil palm is one of the most productive oil bearing crops grown in Southeast Asia. Due to the dwindling availability of agricultural land and increasing demand for high yielding oil palm seedlings, clonal propagation is vital to the oil palm industry. Most commonly, leaf explants are used for in vitro micropropagation of oil palm and to optimize this process it is important to unravel the physiological and molecular mechanisms underlying somatic embryo production from leaves. In this study, a proteomic approach was used to determine protein abundance of mature oil palm leaves. To do this, leaf proteins were extracted using TCA/acetone precipitation protocol and separated by 2DE. A total of 191 protein spots were observed on the 2D gels and 67 of the most abundant protein spots that were consistently observed were selected for further analysis with 35 successfully identified using MALDI TOF/TOF MS. The majority of proteins were classified as being involved in photosynthesis, metabolism, cellular biogenesis, stress response, and transport. This study provides the first proteomic assessment of oil palm leaves in this important oil crop and demonstrates the successful identification of selected proteins spots using the Malaysian Palm Oil Board (MPOB) Elaeis guineensis EST and NCBI-protein databases. The MS data have been deposited in the ProteomeXchange Consortium database with the data set identifier PXD001307.
  3. Thong KS, Chang CT, Lee M, Lee JCY, Tan HS, Shafie AA
    Antimicrob Resist Infect Control, 2021 02 04;10(1):29.
    PMID: 33541440 DOI: 10.1186/s13756-021-00892-0
    BACKGROUND: Antibiotic resistance is a major public health concern, accelerated by antibiotic overuse. Inadequate knowledge among the public has been associated with inappropriate use of antibiotics. This study determined the impact of a self-developed educational leaflet for addressing specific knowledge gaps in antibiotic use among the public.

    METHODS: This was an experimental study conducted at five hospitals and 20 primary health care clinics in the state of Perak. Adults over 18 years of age were recruited using sequential sampling. The first phase of data collection consisted of a pre-intervention assessment, an educational session, and an immediate post-intervention assessment. Each educational session was conducted by trained pharmacists and lasted approximately 15 min for each participant. A two-week post-intervention assessment was then conducted via a phone call to re-assess the participants using the same questionnaire.

    RESULTS: Out of 300 questionnaires distributed, 234 were completed for our study. The mean age of participants was 40.7 ± 14.6 years old. Most of the respondents were female (143, 61.1%), Malay (162, 69.2%), and had tertiary education (162, 69.2%). A mean score was generated for each domain, with knowledge towards antibiotic resistance: 2.83 ± 1.28 pre-intervention, 3.76 ± 0.62 immediate post-intervention, and 3.67 ± 0.78 two-weeks post-intervention (total score: 4.00); knowledge towards antibiotic use: 2.03 ± 1.56 pre-intervention, 4.56 ± 1.46 immediate post-intervention, and 4.32 ± 1.48 two-weeks post-intervention (total score: 6.00); perception towards antibiotic use: 2.83 ± 1.38 pre-intervention, 4.25 ± 1.06 immediate post-intervention, and 4.22 ± 1.02 two-weeks post-intervention (total score: 5.00). Significant improvement in the mean scores were found before and after intervention in all domains (p 

  4. Tan HS, Yan P, Agustie HA, Loh HS, Rayamajhi N, Fang CM
    Lett Appl Microbiol, 2023 Jan 23;76(1).
    PMID: 36688778 DOI: 10.1093/lambio/ovac044
    Extended-spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases (AmpCs)-producing Enterobacteriaceae have been increasingly reported and imposing significant threat to public. Livestock production industry might be the important source for clinically important ESBL-producing Enterobacteriaceae. This study aims to investigate the resistance profile, phenotypic ESBL production, beta-lactamase genes, virulence factors, and plasmid replicon types among 59 Enterobacteriaceae strains isolated from poultry faecal samples in Malaysia's commercial poultry farm. There were 38.7% and 32.3% of Escherichia coli resistant to cefotaxime and cefoxitin, respectively, while Klebsiellaspp. demonstrated resistance rate of 52.6% to both mentioned antimicrobials. Majority of the E. coli isolates carried blaTEM and blaCMY-2 group. blaSHV was the most prevalent gene detected in Klebsiellaspp., followed by blaDHA and blaTEM. Resistance to extended spectrum cephalosporin in our isolates was primarily mediated by plasmid mediated AmpC beta-lactamase such as CMY-2 group and DHA enzyme. The CTX-M genes were found in two ESBL-producing E. coli. IncF, IncI1, and IncN plasmids were most frequently detected in E. coli and Klebsiellaspp. The virulence factor, including EAST1 and pAA were identified at low frequency. This study highlights the poultry as a reservoir of resistance and virulence determinants and prevalence of plasmids in Enterobacteriaceae might drive their dissemination.
  5. Ting ASY, Zoqratt MZHM, Tan HS, Hermawan AA, Talei A, Khu ST
    3 Biotech, 2021 Feb;11(2):40.
    PMID: 33479595 DOI: 10.1007/s13205-020-02617-3
    Microbial communities from a lake and river flowing through a highly dense urbanized township in Malaysia were profiled by sequencing amplicons of the 16S V3-V4 and 18S V9 hypervariable rRNA gene regions via Illumina MiSeq. Results revealed that Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were the dominant prokaryotic phyla; whereas, eukaryotic communities were predominantly of the SAR clade and Opisthokonta. The abundance of Pseudomonas and Flavobacterium in all sites suggested the possible presence of pathogens in the urban water systems, supported by the most probable number (MPN) values of more than 1600 per 100 mL. Urbanization could have impacted the microbial communities as transient communities (clinical, water-borne and opportunistic pathogens) coexisted with common indigenous aquatic communities (Cyanobacteria). It was concluded that in urban water systems, microbial communities vary in their abundance of microbial phyla detected along the water systems. The influences of urban land use and anthropogenic activities influenced the physicochemical properties and the microbial dynamics in the water systems.

    Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-020-02617-3.

  6. Wong BC, Law SKK, Md Zoqratt MZH, Ayub Q, Tan HS
    R Soc Open Sci, 2024 Jun;11(6):232025.
    PMID: 39100177 DOI: 10.1098/rsos.232025
    Shigella causes shigellosis that requires antibiotic treatment in severe cases. Sublethal antibiotic concentrations can promote resistance, but their effect on antibiotic-sensitive bacteria before resistance development is unclear. This study investigated the effects of sublethal norfloxacin (NOR) challenges on a NOR-sensitive strain, Shigella sonnei UKMCC1015. Firstly, the whole genome of S. sonnei UKMCC1015 was assembled, and 45 antimicrobial resistance (AMR) genes were identified. Interestingly, transcriptomic analysis showed that low NOR levels do not change either the expression of the AMR genes or NOR targets such as gyrA. Instead, multiple ribosomal protein genes were downregulated, which could be attributed to decreased ribosomal protein promoter activity, modulated by elevated guanosine pentaphosphate and tetraphosphate (ppGpp) levels. This alarmone is involved in the bacterial stringent response during environmental stress, and it is mainly produced from the ppGpp synthetase (relA). Additionally, we observed that a relA overexpression (prolonged period of elevated ppGpp levels) may negatively affect the NOR tolerance of the bacteria. In conclusion, this study revealed that a NOR-sensitive strain responds differently to sublethal NOR than commonly reported in resistant strains.
  7. Chan KF, Tan CW, Yeo DS, Tan HS, Tan FL, Tan EW, et al.
    J Occup Rehabil, 2011 Mar;21 Suppl 1:S69-76.
    PMID: 21328063 DOI: 10.1007/s10926-011-9289-1
    INTRODUCTION: Asia is the new and favored magnet of economic attention and foreign investments after it made an almost uneventful rebound from the depths of financial crisis of 2008/2009. Not many Western observers fully understand the diversity that is Asia other than perhaps its 2 growing economic giants of China and India. Indeed many smaller countries like Singapore and Malaysia in South East Asia along with Australia and Hong Kong (a Special Administrative Region within China) look to symbiotic relationships with these two economic giants. The purpose of this discussion paper is to examine the current issues related to the development and provision of occupational rehabilitation services in Singapore and Malaysia with a forward-looking view of how Asia's different developing societies could potentially benefit from better alignment of occupational rehabilitation practices and sharing of expertise through international collaboration and dialogue platforms.

    METHODS: Seven therapists and one physician who are frequently involved in occupational rehabilitation services in their home countries critically reviewed the current issues in Singapore and Malaysia which included analysis of the prevalence and cost of occupational injury; overview of workers' compensation system; current practices, obstacles, and challenges in providing occupational rehabilitation and return to work practices. They also offered opinions about how to improve the occupational rehabilitation programs of their two home countries.

    CONCLUSION: Even though Malaysia and Singapore are two different countries, in many ways their current provision of occupational rehabilitation services and the problems they face with are very similar. There is a lot of room for systemic improvements that require government support and action. Most prominently, the training of more healthcare professionals in the assessment and rehabilitation of the injured worker should be encouraged. There could be better liaison between the many stakeholders and more funding made available to develop resources and to jump start strategic programs. As these two countries are witnessing rapid economic growth, more resources should be allocated to establish holistic care of the injured workers emphasizing early interventions and prevention of chronic disabilities.

  8. Chua KB, Voon K, Crameri G, Tan HS, Rosli J, McEachern JA, et al.
    PLoS One, 2008;3(11):e3803.
    PMID: 19030226 DOI: 10.1371/journal.pone.0003803
    First discovered in the early 1950s, reoviruses (respiratory enteric orphan viruses) were not associated with any known disease, and hence named orphan viruses. Recently, our group reported the isolation of the Melaka virus from a patient with acute respiratory disease and provided data suggesting that this new orthoreovirus is capable of human-to-human transmission and is probably of bat origin. Here we report yet another Melaka-like reovirus (named Kampar virus) isolated from the throat swab of a 54 year old male patient in Kampar, Perak, Malaysia who was suffering from high fever, acute respiratory disease and vomiting at the time of virus isolation. Serological studies indicated that Kampar virus was transmitted from the index case to at least one other individual and caused respiratory disease in the contact case. Sequence analysis of the four small class genome segments indicated that Kampar and Melaka viruses are closely related. This was confirmed by virus neutralization assay, showing an effective two-way cross neutralization, i.e., the serum against one virus was able to neutralize the other. Although the exact origin of Kampar virus is unknown, epidemiological tracing revealed that the house of the index case is surrounded by fruit trees frequently visited by fruit bats. There is a high probability that Kampar virus originated from bats and was transmitted to humans via bat droppings or contaminated fruits. The discovery of Kampar virus highlights the increasing trend of emergence of bat zoonotic viruses and the need to expand our understanding of bats as a source of many unknown viruses.
  9. Rushdan MN, Tay EH, Khoo-Tan HS, Lee KM, Low JH, Ho TH, et al.
    Ann Acad Med Singap, 2004 Jul;33(4):467-72.
    PMID: 15329758
    INTRODUCTION: The traditional indications for adjuvant pelvic radiotherapy (RT) for International Federation of Obstetrics and Gynecology (FIGO) stage Ib1 lymph nodes-negative cervix carcinoma following radical surgery based on histopathological factors, such as deep stromal invasion and lymphovascular space invasion (LVSI), were often inconsistently applied. The perceived risk of relapse was subjectively determined. This pilot study attempts to determine if the treatment outcome will be affected when the indication for RT is based on the Gynecologic Oncology Group (GOG) Risk Score (RS) and the field of adjuvant RT is tailored to the RS.

    MATERIALS AND METHODS: From 1997 to 1999, 55 patients with FIGO stage Ib1 lymph nodes-negative cervical carcinoma limited to the cervix were prescribed RT following radical surgery, based on their RS, as follows: RS <40, RT is omitted; RS >40 to <120, modified (smaller) field RT; and RS >120, standard field pelvic RT. Their incidence and site of recurrence were compared with a similar cohort of 40 patients who were treated prior to 1997.

    RESULTS: Prior to 1997, of the 40 patients, 10 patients were given standard field RT. There were 2 (5%) recurrent diseases. The mean duration of follow-up was 61.6 months (range, 1 to 103 months). The RS of 23 of the 30 patients who were not given RT were available. The mean RS was 22 with 5 patients having a score of >40. From 1997 onwards, of the 55 patients, 28 (51%) did not require RT, 13 (23%) were treated with modified (smaller) field RT and 14 (26%) were given standard field RT. There were 2 (3.6%) cases of relapse. The mean duration of follow-up was 36.4 months (range, 5 to 60 months). All patients with a RS of <40 did not suffer any relapse. Their survival outcomes were better when compared to patients who did not have any RT in the GOG Study.

    CONCLUSIONS: The results of this study indicated that postoperative adjuvant RT given to patients with a high GOG RS of >120, significantly improved their 5-year recurrence rate and disease-free survival, as compared with the similar group of patients who were without adjuvant therapy in the GOG study. Patients with a GOG risk-score of <40 may be safely spared from adjuvant pelvic RT. The current treatment protocol did not compromise the outcome in patients, compared with the use of a less precise treatment protocol in the past.

  10. Tan HS, Balasubramaniam IS, Hss AS, Yeong ML, Chew CC, Singh RP, et al.
    BMC Pediatr, 2019 05 29;19(1):174.
    PMID: 31142302 DOI: 10.1186/s12887-019-1550-3
    BACKGROUND: Prolonged neonatal jaundice (PNNJ) is often caused by breast milk jaundice, but it could also point to other serious conditions (biliary atresia, congenital hypothyroidism). When babies with PNNJ receive a routine set of laboratory investigations to detect serious but uncommon conditions, there is always a tendency to over-investigate a large number of well, breastfed babies. A local unpublished survey in Perak state of Malaysia revealed that the diagnostic criteria and initial management of PNNJ were not standardized. This study aims to evaluate and improve the current management of PNNJ in the administrative region of Perak.

    METHODS: A 3-phase quasi-experimental community study was conducted from April 2012 to June 2013. Phase l was a cross-sectional study to review the current practice of PNNJ management. Phase ll was an interventional phase involving the implementation of a new protocol. Phase lll was a 6 months post-interventional audit. A registry of PNNJ was implemented to record the incidence rate. A self-reporting surveillance system was put in place to receive any reports of biliary atresia, urinary tract infection, or congenital hypothyroidism cases.

    RESULTS: In Phase I, 12 hospitals responded, and 199 case notes were reviewed. In Phase II, a new protocol was developed and implemented in all government health facilities in Perak. In Phase III, the 6-month post-intervention audit showed that there were significant improvements when comparing mean scores of pre- and post-intervention: history taking scores (p 

  11. Muzahid NH, Hussain MH, Huët MAL, Dwiyanto J, Su TT, Reidpath D, et al.
    Microb Genom, 2023 Apr;9(4).
    PMID: 37018035 DOI: 10.1099/mgen.0.000977
    Acinetobacter baumannii is a common cause of multidrug-resistant (MDR) nosocomial infections around the world. However, little is known about the persistence and dynamics of A. baumannii in a healthy community. This study investigated the role of the community as a prospective reservoir for A. baumannii and explored possible links between hospital and community isolates. A total of 12 independent A. baumannii strains were isolated from human faecal samples from the community in Segamat, Malaysia, in 2018 and 2019. Another 15 were obtained in 2020 from patients at the co-located tertiary public hospital. The antimicrobial resistance profile and biofilm formation ability were analysed, and the relatedness of community and hospital isolates was determined using whole-genome sequencing (WGS). Antibiotic profile analysis revealed that 12 out of 15 hospital isolates were MDR, but none of the community isolates were MDR. However, phylogenetic analysis based on single-nucleotide polymorphisms (SNPs) and a pangenome analysis of core genes showed clustering between four community and two hospital strains. Such clustering of strains from two different settings based on their genomes suggests that these strains could persist in both. WGS revealed 41 potential resistance genes on average in the hospital strains, but fewer (n=32) were detected in the community strains. In contrast, 68 virulence genes were commonly seen in strains from both sources. This study highlights the possible transmission threat to public health posed by virulent A. baumannii present in the gut of asymptomatic individuals in the community.
  12. Muzahid NH, Md Zoqratt MZH, Ten KE, Hussain MH, Su TT, Ayub Q, et al.
    Sci Rep, 2023 Aug 03;13(1):12596.
    PMID: 37537198 DOI: 10.1038/s41598-023-39642-0
    Acinetobacter species are widely known opportunistic pathogens causing severe community and healthcare-associated infections. One such emerging pathogen, Acinetobacter colistiniresistens, is known to exhibit intrinsic resistance to colistin. We investigated the molecular characteristics of A. colistiniresistens strain C-214, isolated from the fecal sample of a healthy community member, as part of a cohort study being conducted in Segamat, Malaysia. Comparison of the whole genome sequence of C-214 with other A. colistiniresistens sequences retrieved from the NCBI database showed 95% sequence identity or more with many of the genome sequences representing that species. Use of the Galleria mellonella killing assay showed that C-214 was pathogenic in this model infection system. The strain C-214 had a colistin and polymyxin B MIC of 32 and 16 mg/L, respectively. Besides, it was resistant to cefotaxime, amikacin, and tetracycline and showed moderate biofilm-producing ability. Different genes associated with virulence or resistance to major classes of antibiotics were detected. We observed mutations in lpxA/C/D in C-214 and other A. colistiniresistens strains as probable causes of colistin resistance, but the biological effects of these mutations require further investigation. This study provides genomic insights into A. colistiniresistens, a potentially pathogenic bacterium isolated from a community member and notes the public health threat it may pose.
  13. Jana S, Do TN, Nowakowski PJ, Khyasudeen MF, Le DV, Lim IJY, et al.
    J Phys Chem B, 2023 Aug 24;127(33):7309-7322.
    PMID: 37579317 DOI: 10.1021/acs.jpcb.3c02521
    In a two-dimensional (2D) optical spectrum of a multilevel system, there are diagonal peaks and off-diagonal cross-peaks that correlate the different levels. The time-dependent properties of these diagonal peaks and cross-peaks contain much information about the dynamics of the multilevel system. The time-dependent diagonal peakshape that depends on the spectral diffusion dynamics of the associated transition and characterized by the frequency-fluctuation correlation function (FFCF) is well studied. However, the time-dependent peakshape of a cross-peak that provides the correlation dynamics between different transitions is much less studied or understood. We derived the third-order nonlinear response functions that describe the cross-peaks in a 2D electronic spectrum of a multilevel system that arise from processes sharing a common ground state and/or from internal conversion and population transfer. We can use the center line slope (CLS) analysis to characterize the cross-peaks in conjunction with the diagonal peaks. This allows us to recover the frequency-fluctuation cross-correlation functions (FXCFs) between two transitions. The FXCF and its subsidiary quantities such as the initial correlation and the initial covariance between different transitions are important for studying the correlation effects between states in complex systems, such as energy-transfer processes. Furthermore, knowledge of how various molecular processes over different timescales affect simultaneously different transitions can also be obtained from the measured FXCF. We validated and tested our derived equations and analysis process by studying, as an example, the 2D electronic spectra of metal-free phthalocyanine in solution. We measured and analyzed the diagonal peaks of the Qx and Qy transitions and the cross-peaks between these two transitions of this multilevel electronic system and obtained the associated FFCFs and FXCFs. In this model system, we measured negative components of FXCF over the tens of picosecond timescale. This suggests that in phthalocyanine, the Qx and Qy transitions coupling with the solvent molecule motion are anticorrelated to each other.
  14. Chang CT, Mohd Shariff SM, Abu Bakar NS, Ramzuzzaman NS, Lim CK, Lim EYJ, et al.
    J Pharm Policy Pract, 2023 Jan 12;16(1):2.
    PMID: 36635766 DOI: 10.1186/s40545-022-00504-1
    INTRODUCTION: Older adults are among the most vulnerable groups during the COVID-19 epidemic, contributing to a large proportion of COVID-19-related death. Medication review and reconciliation by pharmacist can help reduce the number of potentially inappropriate medications but these services were halted during COVID-19.

    AIM: To assess the prevalence and factors associated with inappropriate medicine use among older populations with COVID-19.

    METHODS: This was a cross-sectional, retrospective analysis of medications among hospitalized older adults with COVID-19. Potentially inappropriate medication use was categorized using the Beer's and STOPP criteria.

    RESULTS: Combining both criteria, 181 (32.7%) of the 553 patients were identified to have used at least one or more potentially inappropriate medication. A marginally higher number of inappropriate medications was documented using the Beers 2019 criteria (151 PIM in 124 patients) compared to STOPP criteria (133 PIMS in 104 patients). The long-term use of proton pump inhibitors (n = 68; 12.3%) and drugs which increases the risk of postural hypotension were the most commonly reported PIM (n = 41; 7.4%). Potentially inappropriate medication use was associated with previous history of hospital admission in the past 12 months (Odds ratio [OR]: 2.27; 95% CI 1.29-3.99) and higher number of discharge medications.

    CONCLUSIONS: Nearly, one in three older adults with COVID-19 had been prescribed a PIM, and the proportion of older adults with polypharmacy increased after discharge. This highlights the importance of having clinical pharmacist conducting medication reviews to identify PIMs and ensure medication appropriateness.

  15. Kwan MSK, Tan SL, Keowmani T, Goh SL, Voo JYH, Tan HS, et al.
    Asia Pac Allergy, 2023 Sep;13(3):121-126.
    PMID: 37744958 DOI: 10.5415/apallergy.0000000000000115
    BACKGROUND: Given the deficits in allergists and testing capacity, the diagnosis of drug allergy is largely dependent on the clinician's and pharmacist's judgment. The ability to recognize drug allergies and respond appropriately is crucial to patient safety. Currently, there is a void in the evidence that limits the ability to recommend comprehensive and swift improvements on this front.

    OBJECTIVE: This study thus aimed to evaluate the knowledge, attitude, and practice toward drug allergy among doctors and pharmacists working in public healthcare facilities in Sabah, Malaysia.

    METHODS: This cross-sectional study was conducted in 24 hospitals and 11 clinics in Sabah. A validated Drug Allergy Knowledge, Attitude, and Practice Questionnaire was adapted from a published study and developed on an online survey platform. The questionnaire was distributed to all listed eligible respondents via email and personal messenger service.

    RESULTS: A total of 549 doctors and pharmacists responded, with an overall response rate of 18.2%. The total mean knowledge, attitude, and practice scores were 8.3 (SD, 1.98), 18.9 (SD, 2.55), and 17.3 (SD, 4.4), respectively. It was found that pharmacists performed significantly poorer than both medical officers (mean score difference = -0.5; P = 0.006) and specialists (mean score difference = -0.9; P = 0.020) in the knowledge domain. As the time in service doubles, the knowledge score increases significantly by 0.3 (P = 0.015).

    CONCLUSION: Knowledge, attitude, and practice on drug allergy among doctors and pharmacists in Sabah were poor. It is thus timely for advanced educational programs on drug allergy to be formalized and implemented.

  16. Rahman AY, Usharraj AO, Misra BB, Thottathil GP, Jayasekaran K, Feng Y, et al.
    BMC Genomics, 2013;14:75.
    PMID: 23375136 DOI: 10.1186/1471-2164-14-75
    Hevea brasiliensis, a member of the Euphorbiaceae family, is the major commercial source of natural rubber (NR). NR is a latex polymer with high elasticity, flexibility, and resilience that has played a critical role in the world economy since 1876.
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