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Fulltext Perception of Current Educational Environment, Clinical Competency, and Depression among Malaysian Medical Students in Clinical Clerkship: A Cross-Sectional Study

Sudi R, Chang WL, Arshad NH, Zainal Abidin SN, Suderman U, Woon LS

Int J Environ Res Public Health, 2022 Dec 05;19(23).
PMID: 36498345 DOI: 10.3390/ijerph192316274

The COVID-19 pandemic has altered the educational environment of medical students in clinical clerkship, with potential impacts on clinical competency and reported increased prevalence of depression. This study aimed to determine the relationship between the perception of the educational environment, self-perceived clinical competency, and depression among them. Subjects (N = 196) at the National University of Malaysia participated through convenience sampling in an online survey including sociodemographic data, COVID-19-related stressors, Dundee Ready Education Environment Measure (DREEM), self-perceived clinical competency, and Patient Health Questionnaire (PHQ-9). The cut-off point for depression was a PHQ-9 score ≥ 15. Multiple logistic regression followed bivariate analyses to identify factors for depression. The participants (mean age: 23.2 years, SD ± 0.98 years) were mainly female (71.9%) and Malay (59.2%). The prevalence of depression was 17.4% (95% CI: 12.3-23.4%). Most participants perceived the educational environment positively. In logistic regression, ethnicity (Adjusted OR = 3.1, 95% CI: 1.2-8.1) and DREEM score were significantly associated with depression, whereas self-perceived clinical competency was not. A higher DREEM score indicating a better perception of the educational environment was linked to a lower likelihood of depression (p = 0.046). Besides ethnicity, perception of the educational environment emerged as a factor associated with depression. This relationship between the educational environment and mental well-being warrants further exploration.
Fulltext Evaluation of diet quality and its associated factors among adolescents in Kuala Lumpur, Malaysia

Rezali FW, Chin YS, Mohd Shariff Z, Mohd Yusof BN, Sanker K, Woon FC

Nutr Res Pract, 2015 Oct;9(5):511-6.
PMID: 26425281 DOI: 10.4162/nrp.2015.9.5.511

This study aims to determine contribution of meal frequency, self-efficacy for healthy eating, and availability of healthy foods towards diet quality of adolescents in Kuala Lumpur, Malaysia.
The effect of post-mortem computed tomography angiography (PMCTA) on biomarkers of coronary artery disease

Woon CK, Omar E, Siew SF, Nawawi HM, Kasim NAM, Chainchel Singh MK

J Forensic Leg Med, 2024 Feb 01;102:102654.
PMID: 38310784 DOI: 10.1016/j.jflm.2024.102654

Coronary atherosclerosis is due to build-up of plaque within the coronary arteries. Post-mortem computed tomography (PMCT) allows non or minimally invasive visualization of abnormalities prior to an autopsy, however PMCT-angiography (PMCTA) greatly enhances relevant findings, especially in viewing the cardiovascular system which is important in the diagnosis of coronary atherosclerosis. Contrast media used in PMCTA however has been reported to cause distortion of tissue which may interfere with post-mortem investigation outcomes. A cross sectional study to investigate the effect of PMCTA on tissue biomarkers in coronary arteries was performed involving cases brought in dead to the Institute and Accident and Emergency Unit. Sixty-three autopsy cases were included in this study, whereby 18 cases underwent PMCT while 45 cases underwent PMCTA. The subjects subsequently had a conventional autopsy where coronary artery sections were collected for standard histological examination and immunohistochemistry examination for endothelial inflammatory (CD36), prothrombogenic (TPA) and plaque stability (MMP-9) markers. The subjects consisted of 55 males and 8 females with a mean age ±SD of 49 ± 18.11 years. There were no significant differences in the coronary artery endothelial expression of CD36, MMP-9 and TPA between PMCT and PMCTA subjects. PMCTA does not alter CD36, TPA and MMP-9 markers supporting the safe use of PMCTA in post-mortem examinations.
Forecasting meteorological impacts on the environmental sustainability of a large-scale solar plant via artificial intelligence-based life cycle assessment

Wan MJ, Phuang ZX, Hoy ZX, Dahlan NY, Azmi AM, Woon KS

Sci Total Environ, 2024 Feb 20;912:168779.
PMID: 38016556 DOI: 10.1016/j.scitotenv.2023.168779

Although large-scale solar (LSS) is a promising renewable energy technology, it causes adverse impacts on the ecosystem, human health, and resource depletion throughout its upstream (i.e., raw material extraction to solar panel production) and downstream (i.e., plant demolition and waste management) processes. The LSS operational performance also fluctuates due to meteorological conditions, leading to uncertainty in electricity generation and raising concerns about its overall environmental performance. Hitherto, there has been no evidence-backed study that evaluates the ecological sustainability of LSS with the consideration of meteorological uncertainties. In this study, a novel integrated Life Cycle Assessment (LCA) and Artificial Neural Network (ANN) framework is developed to forecast the meteorological impacts on LSS's electricity generation and its life cycle environmental sustainability. For LCA, 18 impact categories and three damage categories are characterised and assessed by ReCiPe 2016 via SimaPro v. 9.1. For ANN, a feedforward neural network is applied via Neural Designer 5.9.3. Taking an LSS plant in Malaysia as a case study, the photovoltaic panel production stage contributes the highest environmental impact in LSS (30 % of human health, 30 % of ecosystem quality, and 34 % of resource scarcity). Aluminium recycling reduces by 10 % for human health, 10 % for ecosystem quality, and 9 % for resource scarcity. The emissions avoided by the forecasted LSS-generated electricity offset the environmental burden for human health, ecosystem quality, and resource scarcity 12-68 times, 13-73 times, and 18-98 times, respectively. The developed ANN-LCA framework can provide LSS stakeholders with data-backed insights to effectively design an environmentally conscious LSS facility, considering meteorological influences.
Municipal solid waste management for low-carbon transition: A systematic review of artificial neural network applications for trend prediction

Hoy ZX, Phuang ZX, Farooque AA, Fan YV, Woon KS

Environ Pollut, 2024 Mar 01;344:123386.
PMID: 38242306 DOI: 10.1016/j.envpol.2024.123386

Improper municipal solid waste (MSW) management contributes to greenhouse gas emissions, necessitating emissions reduction strategies such as waste reduction, recycling, and composting to move towards a more sustainable, low-carbon future. Machine learning models are applied for MSW-related trend prediction to provide insights on future waste generation or carbon emissions trends and assist the formulation of effective low-carbon policies. Yet, the existing machine learning models are diverse and scattered. This inconsistency poses challenges for researchers in the MSW domain who seek to identify and optimize the machine learning techniques and configurations for their applications. This systematic review focuses on MSW-related trend prediction using the most frequently applied machine learning model, artificial neural network (ANN), while addressing potential methodological improvements for reducing prediction uncertainty. Thirty-two papers published from 2013 to 2023 are included in this review, all applying ANN for MSW-related trend prediction. Observing a decrease in the size of data samples used in studies from daily to annual timescales, the summarized statistics suggest that well-performing ANN models can still be developed with approximately 33 annual data samples. This indicates promising opportunities for modeling macroscale greenhouse gas emissions in future works. Existing literature commonly used the grid search (manual) technique for hyperparameter (e.g., learning rate, number of neurons) optimization and should explore more time-efficient automated optimization techniques. Since there are no one-size-fits-all performance indicators, it is crucial to report the model's predictive performance based on more than one performance indicator and examine its uncertainty. The predictive performance of newly-developed integrated models should also be benchmarked to show performance improvement clearly and promote similar applications in future works. The review analyzed the shortcomings, best practices, and prospects of ANNs for MSW-related trend predictions, supporting the realization of practical applications of ANNs to enhance waste management practices and reduce carbon emissions.
Risk factors for fragility fracture in Seremban district, Malaysia: a comparison of patients with fragility fracture in the orthopedic ward versus those in the outpatient department

Loh KY, Shong KH, Lan SN, Lo WY, Woon SY

Asia Pac J Public Health, 2008;20(3):251-7.
PMID: 19124319 DOI: 10.1177/1010539508317130

Osteoporosis is a silent disease and becomes clinically significant in the presence of fragility fracture. Identifying risk factors that are associated with osteoporosis in the community is important in reducing the incidence of fragility fracture. The aim of this study is to identify risk factors associated with fragility fracture in the Seremban District of Malaysia. This is a population comparison study between orthopedic ward patients and outpatients attending a community health clinic for 6 months. Epidemiological data and the possible risk factors for osteoporosis were collected by direct interview. This study demonstrates that advancing age, low body weight, smoking, lack of regular exercise, low consumption of calcium containing foods, and using bone depleting drugs (steroids, thyroid hormone, and frusemides) are major risk factors for fragility fracture. Most of these risk factors are modifiable through effective lifestyle intervention.
Study site: Klinik Kesihatan Seremban; Hospital Seremban, Negeri Sembilan, Malaysia
Medicare-reimbursed psychiatric consultations before and after telehealth expansion in Australia: a time series study

Woon LS, Maguire PA, Reay RE, Mittinty M, Bastiampillai T, Looi JCL

Aust Health Rev, 2024 Dec;48(6):617-625.
PMID: 39433299 DOI: 10.1071/AH24196

Objective Telepsychiatry consultations grew rapidly with increased total consultations and reduced face-to-face consultations following the pandemic-triggered expansion of Medicare Benefits Schedule (MBS) telehealth items. It was unclear how much telehealth expansion independently impacted overall and face-to-face consultation trends after accounting for lockdown severity. Methods We extracted monthly MBS Item Reports for psychiatric consultations (January 2012-December 2023). The monthly average Stringency Index (SI) for Australia represented lockdown severity from January 2020 to December 2022. A dichotomous variable denoted telehealth expansion (March 2020 onward). We constructed consecutive multiple linear regression models for combined consultations and face-to-face consultations to include seasonality, trend, SI, and telehealth expansion. We compared model performance using information criteria. Results Median monthly total consultations increased from 148,413 (Interquartile range, IQR: 138,219-153,709) pre-expansion (January 2012-February 2020) to 173,016 (IQR: 158,292-182,463) post-expansion (March 2020-December 2023). Contrarily, median monthly face-to-face consultations decreased from 143,726 (IQR: 135,812-150,153) to 99,272 (IQR: 87,513-107,778). Seasonality and trend were present in both time series. The time series regression model with expansion but excluding SI best explained all consultations, while both telehealth expansion and SI were significant in the best-fit model for face-to-face consultations. Conclusion MBS telehealth expansion was associated with total and face-to-face consultations independent of lockdown severity changes. Policy changes allowing wider access to new telehealth services have possibly led to increased uptake of psychiatric care and addressed previously unmet needs.
Online interest in ADHD predicts ADHD medication prescriptions in Australia from 2004 to 2023: A time-series analysis revealing COVID-19-related acceleration

Sy-Cherng Woon L, Smith D, Alllison S, Looi JC, Bastiampillai T

Australas Psychiatry, 2025 Jan 18.
PMID: 39825766 DOI: 10.1177/10398562251315006

OBJECTIVE: Attention-deficit hyperactivity disorder (ADHD) medication prescriptions in Australia have grown sharply in recent years. We examined the association between online interest in ADHD and prescriptions.
METHODS: Monthly Pharmaceutical Benefits Scheme (PBS) and Repatriation PBS (RPBS) Item Reports of ADHD prescriptions and Australian ADHD-related Google Trends (GT) data (2004-2023) were sourced. We modelled the lagged effect of GT on ADHD medication prescriptions, using an autoregressive moving average model with autoregressive conditional heteroskedasticity, adjusting for COVID-19 lockdown effects. Results were compared to a model of GT for pain-related searches and PBS/RPBS opioid prescriptions, and counterfactual alternatives: (1) ADHD-related GT and opioid prescriptions and (2) pain-related GT and ADHD prescriptions. We descriptively analysed additional ADHD-related online news data.
RESULTS: Annual prescriptions doubled from 1,424,904 in 2020 to 3,112,072 in 2023. ADHD medication prescriptions and ADHD-related GT considerably increased since the COVID-19 pandemic. GT had a statistically significant positive lagged association with ADHD prescriptions. Comparator models did not show statistically significant associations between GT and prescriptions. Online news data supported recently increased public interest in ADHD.
CONCLUSIONS: ADHD-related online interest predicts increased ADHD prescriptions, which was accentuated during the pandemic. Studies are needed to evaluate causal pathways, health information quality and sociodemographic determinants.
Production of an oligosaccharide-specific cellobiohydrolase from the thermophilic fungus Thielavia terrestris

Woon JS, Mackeen MM, Sudin AH, Mahadi NM, Illias RM, Murad AM, et al.

Biotechnol Lett, 2016 May;38(5):825-32.
PMID: 26830095 DOI: 10.1007/s10529-016-2045-z

To express and determine the hydrolytic activity of a cellobiohydrolase (TTCBH6B) from the thermophilic fungus Thielavia terrestris in Pichia pastoris.
Erratum to: Production of an oligosaccharide-specific cellobiohydrolase from the thermophilic fungus Thielavia terrestris

Woon JS, Mackeen MM, Sudin AH, Mahadi NM, Illias RM, Murad AM, et al.

Biotechnol Lett, 2016 May;38(5):833.
PMID: 26914687
Medical cannabis for chronic pain: can it make a difference in pain management?

Maharajan MK, Yong YJ, Yip HY, Woon SS, Yeap KM, Yap KY, et al.

J Anesth, 2020 02;34(1):95-103.
PMID: 31535218 DOI: 10.1007/s00540-019-02680-y

Globally, chronic pain is a major therapeutic challenge and affects more than 15% of the population. As patients with painful terminal diseases may face unbearable pain, there is a need for more potent analgesics. Although opioid-based therapeutic agents received attention to manage severe pain, their adverse drug effects and mortality rate associated with opioids overdose are the major concerns. Evidences from clinical trials showed therapeutic benefits of cannabis, especially delta-9-tetrahydrocannabinol and cannabinoids reduced neuropathic pain intensity in various conditions. Also, there are reports on using combination cannabinoid therapies for chronic pain management. The association of cannabis dependence and addiction has been discussed much and the reports mentioned that it can be comparatively lower than other substances such as nicotine and alcohol. More countries have decided to legalise the medicinal use of cannabis and marijuana. Healthcare professionals should keep themselves updated with the changing state of medical cannabis and its applications. The pharmacokinetics and safety of medical cannabis need to be studied by conducting clinical research. The complex and variable chemically active contents of herbal cannabis and methodological limitations in the administration of cannabis to study participants, make the clinical research difficult.
Fulltext Profiling of Potential Antibacterial Compounds of Lactic Acid Bacteria against Extremely Drug Resistant (XDR) Acinetobacter baumannii

Yap PC, Ayuhan N, Woon JJ, Teh CSJ, Lee VS, Azman AS, et al.

Molecules, 2021 Mar 19;26(6).
PMID: 33808805 DOI: 10.3390/molecules26061727

A total of 20 of isolates of lactic acid bacteria (LAB) were selected and screened for antagonistic activity against clinical strains of 30 clinical isolates of extremely drug-resistant (XDR) Acinetobacter baumannii using the well diffusion assay method. Results showed that 50% of the highly LAB strains possessed inhibitory activity against (up to 66%) of the XDR A. baumannii strains tested. The supernatant of the twenty LAB strains was subjected to gas chromatography mass spectrometry (GCMS) revealed that the common compound found in the active isolates against XDR A. baumannii was 3-Isobutyl-2,3,6,7,8,8a-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione, a known potential diketopiperazine group. The molecular docking study against potential antibacterial targets with selected ligands was performed to predict the binding mode of interactions, which is responsible for antibacterial activity. The docking analysis of the potent compounds supported the potential antibacterial activity exhibiting high inhibition constant and binding affinity in silico.
Fulltext Case Report: Severe Hyponatremia in Infants With Urinary Tract Infection

Abu Bakar K, Jalaludin MY, Zainal N, Woon SL, Mohd Zikre N, Samingan N, et al.

Front Pediatr, 2021;9:655010.
PMID: 34026690 DOI: 10.3389/fped.2021.655010

Introduction: Many reports on investigations and treatments in UTI, however little, have been mentioned with regard to electrolyte abnormalities. Secondary pseudohypoaldosteronism (PHA) in UTI, though less common, is a known association. Features include hyponatremia and concomitant hyperkalemia. Objectives: We aim to highlight these uncommon sequelae in UTI to avoid incorrect diagnosis and unnecessary investigations. Study Design: Clinical data of patients admitted and referred to a pediatric nephrologist at the University Malaya Medical Center between May 2019 and October 2020 were collated and elaborated. Results and Discussion: We report three infants with hyponatremia and hyperkalemia during UTI episodes. Two infants were known to have posterior urethral valve (PUV) before the onset of UTI and one infant had UTI, which led to investigations confirming the diagnosis of bladder vaginal fistula. The electrolyte derangements were temporary and resolved within 48 to 72 h of treatment with intravenous fluid and appropriate antibiotic therapy. Out of three, only one had a hormonal study, which confirms PHA. Reduced aldosterone activity could be due to absolute reduction in aldosterone titer or lack of aldosterone responsiveness at tubular (other tissues) level. In the latter, aldosterone titer is elevated. The infant in our cohort who had hormonal evaluation had the mentioned electrolyte abnormalities with a markedly elevated aldosterone titer. This demonstrated defective action of the hormone at the level of mineralocorticoid receptor. Although the remaining two infants had no confirmatory hormonal study, all of them recovered within 48 h of hospital admission, after receiving appropriate management for the primary problem, which was UTI. We observed a slower recovery of hyponatremia in relation to hyperkalemia, but none of these infants required salt replacement upon discharge. Conclusion: Infants with severe UTI and deranged electrolytes should be screened for structural abnormality and vice versa. Not all infants require hormonal screening, but those who required prolonged salt replacement or showed involvement of other systems warrant further evaluation.
Fulltext Geometric morphometric analysis of malocclusion on lateral cephalograms in Malaysian population

Woon CK, Jamal NAA, Noor MNIM, Abdullah SM, Ibrahim NM, Norman NH, et al.

Anat Cell Biol, 2020 Sep 30;53(3):378.
PMID: 32782237 DOI: 10.5115/acb.19.118e
Fulltext Geometric morphometric analysis of malocclusion on lateral cephalograms in Malaysian population

Woon CK, Jamal NAA, Noor MNIM, Abdullah SM, Mohamed Ibrahim N, Norman NH, et al.

Anat Cell Biol, 2019 12;52(4):397-405.
PMID: 31949978 DOI: 10.5115/acb.19.118

Geometric morphometrics is a new approach for shape identification in diagnosis of malocclusion. Lateral cephalogram is an X-ray that taken for diagnosing malocclusion in dental setting. The aim of this study was to determine the differences of craniofacial shape in malocclusion by application of two-dimensional geometric morphometrics and to compile the database of malocclusion in adult Malaysian population. Lateral cephalogram radiographs of 381 adults Malaysia (age 18-45) were retrieved retrospectively and assigned to three groups according to their occlusion: class I, class II, and class III. The geometric morphometric shape study incorporated nine landmarks and was analyzed in details using tpsUtil p software. Geometric morphometric analysis such was done using MorphoJ software. The results of the principal component's analysis (PCA) yielded 14 main components responsible for 100% of the variation exhibited by the malocclusion with three highly significant PCA. The highest Mahalanobis distances were exhibited by the malocclusion class II and III population. The Procrustes ANOVA showed that the shape effect was highly significant (P<0.01). The discriminant function analysis showed the high percentage of 80% discriminate among the malocclusions after cross-validation. There are significant differences for ANB angle (A point-Nasion-B point) in all malocclusion groups. Class II has the widest ANB angle while class III has the most acute ANB angle. Skeletal shape was clearly associated with dental malocclusion and showed considerable variation. Geometric morphometrics is an alternative research tool and can be used for diagnosing individual classification of malocclusion.
Metallic and semiconducting carbon nanotubes separation using an aqueous two-phase separation technique: a review

Tang MS, Ng EP, Juan JC, Ooi CW, Ling TC, Woon KL, et al.

Nanotechnology, 2016 Aug 19;27(33):332002.
PMID: 27396920 DOI: 10.1088/0957-4484/27/33/332002

It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.
Epidemiological Characteristics of Strongyloidiasis in Inhabitants of Indigenous Communities in Borneo Island, Malaysia

Ngui R, Halim NA, Rajoo Y, Lim YA, Ambu S, Rajoo K, et al.

Korean J Parasitol, 2016 Oct;54(5):673-678.
PMID: 27853126

Epidemiological study on strongyloidiasis in humans is currently lacking in Malaysia. Thus, a cross-sectional study was carried out to determine the prevalence of Strongyloides stercoralis infection among the inhabitants of longhouse indigenous communities in Sarawak. A single stool and blood sample were collected from each participant and subjected to microscopy, serological and molecular techniques. Five species of intestinal parasites were identified by stool microscopy. None of the stool samples were positive for S. stercoralis. However, 11% of 236 serum samples were seropositive for strongyloidiasis. Further confirmation using molecular technique on stool samples of the seropositive individuals successfully amplified 5 samples, suggesting current active infections. The prevalence was significantly higher in adult males and tended to increase with age. S. stercoralis should no longer be neglected in any intestinal parasitic survey. Combination of more than 1 diagnostic technique is necessary to increase the likelihood of estimating the 'true' prevalence of S. stercoralis.
Fulltext Continuous spinal anaesthesia: A retrospective analysis of 318 cases

Beh ZY, Au Yong PS, Lye S, Eapen SE, Yoong CS, Woon KL, et al.

Indian J Anaesth, 2018 Oct;62(10):765-772.
PMID: 30443059 DOI: 10.4103/ija.IJA_387_18

Background and Aims: Continuous spinal anaesthesia (CSA) is an underutilised anaesthetic technique. Our objectives were to evaluate the use of CSA in our institution, its efficacy, ease to use and safety.
Methods: This was a retrospective analysis conducted in a tertiary centre. Records of all patients who underwent surgery and received CSA between December 2008 and July 2017 were reviewed. Their demographic profiles, type and duration of surgery were analysed. The outcomes measured were the success of CSA, technical evaluation and difficulties encountered, intraoperative haemodynamics, usage of vasopressors and any reported complications. Statistical analysis was done using Chi-square test.
Results: Three hundred and eighteen patients (94%) successfully underwent surgery using CSA. Twenty cases (6%) had failed CSA, of which five of them had CSA insertion failure, while the rest failed to complete the operation under CSA, thus requiring conversion to general anaesthesia. Patients who have had an initial intrathecal local anaesthetic (LA) volume ≥1.5 ml had higher odds (odds ratio (OR) 2.78; 95% confidence interval [CI], 1.70-4.57) of developing hypotension compared to those who had <1.5 ml (P < 0.001). There were no reported post-dural puncture headache, neurological sequelae or infection.
Conclusion: CSA is a useful anaesthetic technique with low failure rate. The key to achieving haemodynamic stability is by giving a small initial bolus, then titrating the block up to required height using aliquots of 0.5 ml of intrathecal LA through the catheter.
Fulltext Zika virus infection in Malaysia: an epidemiological, clinical and virological analysis

Woon YL, Lim MF, Tg Abd Rashid TR, Thayan R, Chidambaram SK, Syed Abdul Rahim SS, et al.

BMC Infect Dis, 2019 Feb 13;19(1):152.
PMID: 30760239 DOI: 10.1186/s12879-019-3786-9

BACKGROUND: A major outbreak of the Zika virus (ZIKV) has been reported in Brazil in 2015. Since then, it spread further to other countries in the Americas and resulted in declaration of the Public Health Emergency of International Concern (PHEIC) by World Health Organization. In 2016, Singapore reported its first minor ZIKV epidemic. Malaysia shares similar ecological environment as Brazil and Singapore which may also favor ZIKV transmission. However, no ZIKV outbreak has been reported in Malaysia to date. This study aimed to discuss all confirmed ZIKV cases captured under Malaysia ZIKV surveillance system after declaration of the PHEIC; and explore why Malaysia did not suffer a similar ZIKV outbreak as the other two countries.
METHODS: This was an observational study reviewing all confirmed ZIKV cases detected in Malaysia through the ZIKV clinical surveillance and Flavivirus laboratory surveillance between June 2015 and December 2017. All basic demographic characteristics, co-morbidities, clinical, laboratory and outcome data of the confirmed ZIKV cases were collected from the source documents.
RESULTS: Only eight out of 4043 cases tested positive for ZIKV infection during that period. The median age of infected patients was 48.6 years and majority was Chinese. Two of the subjects were pregnant. The median interval between the onset of disease and the first detection of ZIKV Ribonucleic Acid (RNA) in body fluid was 3 days. Six cases had ZIKV RNA detected in both serum and urine samples. Phylogenetic analysis suggests that isolates from the 7 cases of ZIKV infection came from two clusters, both of which were local circulating strains.
CONCLUSION: Despite similar ecological background characteristics, Malaysia was not as affected by the recent ZIKV outbreak compared to Brazil and Singapore. This could be related to pre-existing immunity against ZIKV in this population, which developed after the first introduction of the ZIKV in Malaysia decades ago. A serosurvey to determine the seroprevalence of ZIKV in Malaysia was carried out in 2017. The differences in circulating ZIKV strains could be another reason as to why Malaysia seemed to be protected from an outbreak.
Fulltext Cellobiohydrolase B of Aspergillus niger over-expressed in Pichia pastoris stimulates hydrolysis of oil palm empty fruit bunches

Woon JS, Mackeen MM, Illias RM, Mahadi NM, Broughton WJ, Murad AMA, et al.

PeerJ, 2017;5:e3909.
PMID: 29038760 DOI: 10.7717/peerj.3909

BACKGROUND: Aspergillus niger, along with many other lignocellulolytic fungi, has been widely used as a commercial workhorse for cellulase production. A fungal cellulase system generally includes three major classes of enzymes i.e., β-glucosidases, endoglucanases and cellobiohydrolases. Cellobiohydrolases (CBH) are vital to the degradation of crystalline cellulose present in lignocellulosic biomass. However, A. niger naturally secretes low levels of CBH. Hence, recombinant production of A. niger CBH is desirable to increase CBH production yield and also to allow biochemical characterisation of the recombinant CBH from A. niger.
METHODS: In this study, the gene encoding a cellobiohydrolase B (cbhB) from A. niger ATCC 10574 was cloned and expressed in the methylotrophic yeast Pichia pastoris X-33. The recombinant CBHB was purified and characterised to study its biochemical and kinetic characteristics. To evaluate the potential of CBHB in assisting biomass conversion, CBHB was supplemented into a commercial cellulase preparation (Cellic(®) CTec2) and was used to hydrolyse oil palm empty fruit bunch (OPEFB), one of the most abundant lignocellulosic waste from the palm oil industry. To attain maximum saccharification, enzyme loadings were optimised by response surface methodology and the optimum point was validated experimentally. Hydrolysed OPEFB samples were analysed using attenuated total reflectance FTIR spectroscopy (ATR-FTIR) to screen for any compositional changes upon enzymatic treatment.
RESULTS: Recombinant CBHB was over-expressed as a hyperglycosylated protein attached to N-glycans. CBHB was enzymatically active towards soluble substrates such as 4-methylumbelliferyl-β-D-cellobioside (MUC), p-nitrophenyl-cellobioside (pNPC) and p-nitrophenyl-cellobiotrioside (pNPG3) but was not active towards crystalline substrates like Avicel(®) and Sigmacell cellulose. Characterisation of purified CBHB using MUC as the model substrate revealed that optimum catalysis occurred at 50 °C and pH 4 but the enzyme was stable between pH 3 to 10 and 30 to 80 °C. Although CBHB on its own was unable to digest crystalline substrates, supplementation of CBHB (0.37%) with Cellic(®) CTec2 (30%) increased saccharification of OPEFB by 27%. Compositional analyses of the treated OPEFB samples revealed that CBHB supplementation reduced peak intensities of both crystalline cellulose Iα and Iβ in the treated OPEFB samples.
DISCUSSION: Since CBHB alone was inactive against crystalline cellulose, these data suggested that it might work synergistically with other components of Cellic(®) CTec2. CBHB supplements were desirable as they further increased hydrolysis of OPEFB when the performance of Cellic(®) CTec2 was theoretically capped at an enzyme loading of 34% in this study. Hence, A. niger CBHB was identified as a potential supplementary enzyme for the enzymatic hydrolysis of OPEFB.

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