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Multiple linear regression and regression with time series error models in forecasting PM10 concentrations in Peninsular Malaysia

Ng KY, Awang N

Environ Monit Assess, 2018 Jan 06;190(2):63.
PMID: 29306973 DOI: 10.1007/s10661-017-6419-z

Frequent haze occurrences in Malaysia have made the management of PM10 (particulate matter with aerodynamic less than 10 μm) pollution a critical task. This requires knowledge on factors associating with PM10 variation and good forecast of PM10 concentrations. Hence, this paper demonstrates the prediction of 1-day-ahead daily average PM10 concentrations based on predictor variables including meteorological parameters and gaseous pollutants. Three different models were built. They were multiple linear regression (MLR) model with lagged predictor variables (MLR1), MLR model with lagged predictor variables and PM10 concentrations (MLR2) and regression with time series error (RTSE) model. The findings revealed that humidity, temperature, wind speed, wind direction, carbon monoxide and ozone were the main factors explaining the PM10 variation in Peninsular Malaysia. Comparison among the three models showed that MLR2 model was on a same level with RTSE model in terms of forecasting accuracy, while MLR1 model was the worst.
Fulltext COVID-19: Development of a robust mathematical model and simulation package with consideration for ageing population and time delay for control action and resusceptibility

Ng KY, Gui MM

Physica D, 2020 Oct;411:132599.
PMID: 32536738 DOI: 10.1016/j.physd.2020.132599

The current global health emergency triggered by the pandemic COVID-19 is one of the greatest challenges we face in this generation. Computational simulations have played an important role to predict the development of the current pandemic. Such simulations enable early indications on the future projections of the pandemic and is useful to estimate the efficiency of control action in the battle against the SARS-CoV-2 virus. The SEIR model is a well-known method used in computational simulations of infectious viral diseases and it has been widely used to model other epidemics such as Ebola, SARS, MERS, and influenza A. This paper presents a modified SEIRS model with additional exit conditions in the form of death rates and resusceptibility, where we can tune the exit conditions in the model to extend prediction on the current projections of the pandemic into three possible outcomes; death, recovery, and recovery with a possibility of resusceptibility. The model also considers specific information such as ageing factor of the population, time delay on the development of the pandemic due to control action measures, as well as resusceptibility with temporal immune response. Owing to huge variations in clinical symptoms exhibited by COVID-19, the proposed model aims to reflect better on the current scenario and case data reported, such that the spread of the disease and the efficiency of the control action taken can be better understood. The model is verified using two case studies based on the real-world data in South Korea and Northern Ireland.
Fulltext Ectopic pregnancy: uncommon presentations and difficulty in diagnosis

Wong CM, Ganesh R, Ng KY

Med J Malaysia, 1999 Mar;54(1):117-9.
PMID: 10972015

Diagnosis of ectopic pregnancy prior to rupture is an arduous task even with the availability of many new investigative methods and imaging modalities. Above all, a high index of suspicion is necessary when dealing with women who present in early pregnancy with abdominal pain and vaginal bleeding. With the increased use of ovulation induction agents, the probability of heterotropic pregnancy should be kept in mind. The use of transvaginal ultrasonography (TVS) will help in earlier diagnosis because of its advantages over transabdominal ultrasonography (TAS).
Fulltext Hydatidiform mole and post-evacuation regression patterns of serum beta human chorionic gonadotrophin

Kamariah K, Satgunasingam N, Nasri NM, Ng KY

Med J Malaysia, 1993 Mar;48(1):40-5.
PMID: 7688063

Eighty-nine patients who had hydatidiform moles evacuated at the General Hospital, Kuala Lumpur, were followed with serum beta hCG determinations from October 1988 to June 1991. A regression curve for serum beta hCG, as measured by RIA, was derived from the results of 47 of the patients who demonstrated spontaneous regression of serum beta hCG titres. All 47 patients had normal serum titres at 135 days after evacuation. The mean time taken to reach normal level was 82.6 days, while the range was 39 to 135 days (5 to 19 weeks).
Assessing the effects of time-dependent restrictions and control actions to flatten the curve of COVID-19 in Kazakhstan

Do TD, Gui MM, Ng KY

PeerJ, 2021;9:e10806.
PMID: 33604187 DOI: 10.7717/peerj.10806

This article presents the assessment of time-dependent national-level restrictions and control actions and their effects in fighting the COVID-19 pandemic. By analysing the transmission dynamics during the first wave of COVID-19 in the country, the effectiveness of the various levels of control actions taken to flatten the curve can be better quantified and understood. This in turn can help the relevant authorities to better plan for and control the subsequent waves of the pandemic. To achieve this, a deterministic population model for the pandemic is firstly developed to take into consideration the time-dependent characteristics of the model parameters, especially on the ever-evolving value of the reproduction number, which is one of the critical measures used to describe the transmission dynamics of this pandemic. The reproduction number alongside other key parameters of the model can then be estimated by fitting the model to real-world data using numerical optimisation techniques or by inducing ad-hoc control actions as recorded in the news platforms. In this article, the model is verified using a case study based on the data from the first wave of COVID-19 in the Republic of Kazakhstan. The model is fitted to provide estimates for two settings in simulations; time-invariant and time-varying (with bounded constraints) parameters. Finally, some forecasts are made using four scenarios with time-dependent control measures so as to determine which would reflect on the actual situations better.
The impact of sleep amount and sleep quality on glycemic control in type 2 diabetes: A systematic review and meta-analysis

Lee SWH, Ng KY, Chin WK

Sleep Med Rev, 2017 02;31:91-101.
PMID: 26944909 DOI: 10.1016/j.smrv.2016.02.001

Recent epidemiological studies have suggested that there is an association between glycemic control and sleep disturbances in patients with type 2 diabetes, but the extent is unclear. A systematic literature search was performed in nine electronic databases from inception until August 2015 without any language restriction. The search identified 20 studies (eight studies reporting duration of sleep and 15 studies evaluating sleep quality), and 15 were included in the meta-analysis. Short and long sleep durations were associated with an increased hemoglobin A1c (HbA1c) (weighted mean difference (WMD): 0.23% [0.10-0.36], short sleep; WMD: 0.13% [0.02-0.25], long sleep) compared to normal sleep, suggesting a U-shaped dose-response relationship. Similarly, poor sleep quality was associated with an increased HbA1c (WMD: 0.35% [0.12-0.58]). Results of this study suggest that amount of sleep as well as quality of sleep is important in the metabolic function of type 2 diabetes patients. Further studies are needed to identify for the potential causal role between sleep and altered glucose metabolism.
Post partum splenic artery aneurysm rupture

Asokan S, Chew EK, Ng KY, Thanaletchimy N, Asmiati A, Kong NM

J Obstet Gynaecol Res, 2000 Jun;26(3):199-201.
PMID: 10932982

Ruptured splenic artery aneurysm during pregnancy is a rare event with high maternal and fetal mortality rate. A case of ruptured splenic artery aneurysm in the post partum period is presented. The literature is reviewed on pathophysiology, clinical presentation and management of this rare and potentially fatal entity.
Pharmacological Effects of Melatonin as Neuroprotectant in Rodent Model: A Review on the Current Biological Evidence

Tan HY, Ng KY, Koh RY, Chye SM

Cell Mol Neurobiol, 2020 Jan;40(1):25-51.
PMID: 31435851 DOI: 10.1007/s10571-019-00724-1

The progressive loss of structure and functions of neurons, including neuronal death, is one of the main factors leading to poor quality of life. Promotion of functional recovery of neuron after injury is a great challenge in neuroregenerative studies. Melatonin, a hormone is secreted by pineal gland and has antioxidative, anti-inflammatory, and anti-apoptotic properties. Besides that, melatonin has high cell permeability and is able to cross the blood-brain barrier. Apart from that, there are no reported side effects associated with long-term usage of melatonin at both physiological and pharmacological doses. Thus, in this review article, we summarize the pharmacological effects of melatonin as neuroprotectant in central nervous system injury, ischemic-reperfusion injury, optic nerve injury, peripheral nerve injury, neurotmesis, axonotmesis, scar formation, cell degeneration, and apoptosis in rodent models.
Tau Proteins and Tauopathies in Alzheimer's Disease

Chong FP, Ng KY, Koh RY, Chye SM

Cell Mol Neurobiol, 2018 Jul;38(5):965-980.
PMID: 29299792 DOI: 10.1007/s10571-017-0574-1

Alzheimer's disease (AD) is characterized by progressive memory loss and cognitive function deficits. There are two major pathological hallmarks that contribute to the pathogenesis of AD which are the presence of extracellular amyloid plaques composed of amyloid-β (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. Despite extensive research that has been done on Aβ in the last two decades, therapies targeting Aβ were not very fruitful at treating AD as the efficacy of Aβ therapies observed in animal models is not reflected in human clinical trials. Hence, tau-directed therapies have received tremendous attention as the potential treatments for AD. Tauopathies are closely correlated with dementia and immunotherapy has been effective at reducing tau pathology and improving cognitive deficits in animal models. Thus, in this review article, we discussed the pathological mechanism of tau proteins, the key factors contributing to tauopathies, and therapeutic approaches for tauopathies in AD based on the recent progress in tau-based research.
Fulltext Exploring Sources of Satisfaction and Dissatisfaction in Airbnb Accommodation Using Unsupervised and Supervised Topic Modeling

Ding K, Choo WC, Ng KY, Ng SI, Song P

Front Psychol, 2021;12:659481.
PMID: 33967922 DOI: 10.3389/fpsyg.2021.659481

This study aims to examine key attributes affecting Airbnb users' satisfaction and dissatisfaction through the analysis of online reviews. A corpus that comprises 59,766 Airbnb reviews form 27,980 listings located in 12 different cities is analyzed by using both Latent Dirichlet Allocation (LDA) and supervised LDA (sLDA) approach. Unlike previous LDA based Airbnb studies, this study examines positive and negative Airbnb reviews separately, and results reveal the heterogeneity of satisfaction and dissatisfaction attributes in Airbnb accommodation. In particular, the emergence of the topic "guest conflicts" in this study leads to a new direction in future sharing economy accommodation research, which is to study the interactions of different guests in a highly shared environment. The results of topic distribution analysis show that in different types of Airbnb properties, Airbnb users attach different importance to the same service attributes. The topic correlation analysis reveals that home like experience and help from the host are associated with Airbnb users' revisit intention. We determine attributes that have the strongest predictive power to Airbnb users' satisfaction and dissatisfaction through the sLDA analysis, which provides valuable managerial insights into priority setting when developing strategies to increase Airbnb users' satisfaction. Methodologically, this study contributes by illustrating how to employ novel approaches to transform social media data into useful knowledge about customer satisfaction, and the findings can provide valuable managerial implications for Airbnb practitioners.
Melatonin receptors: distribution in mammalian brain and their respective putative functions

Ng KY, Leong MK, Liang H, Paxinos G

Brain Struct Funct, 2017 Sep;222(7):2921-2939.
PMID: 28478550 DOI: 10.1007/s00429-017-1439-6

Melatonin, through its different receptors, has pleiotropic functions in mammalian brain. Melatonin is secreted mainly by the pineal gland and exerts its effects via receptor-mediated and non-receptor-mediated actions. With recent advancement in neuroanatomical mapping, we may now understand better the localizations of the two G protein-coupled melatonin receptors MT1 and MT2. The abundance of these melatonin receptors in respective brain regions suggests that receptor-mediated actions of melatonin might play crucial roles in the functions of central nervous system. Hence, this review aims to summarize the distribution of melatonin receptors in the brain and to discuss the putative functions of melatonin in the retina, cerebral cortex, reticular thalamic nucleus, habenula, hypothalamus, pituitary gland, periaqueductal gray, dorsal raphe nucleus, midbrain and cerebellum. Studies on melatonin receptors in the brain are important because cumulative evidence has pointed out that melatonin receptors not only play important physiological roles in sleep, anxiety, pain and circadian rhythm, but might also be involved in the pathogenesis of a number of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease and Huntington's disease.
Cancer risk in Parkinson disease: An updated systematic review and meta-analysis

Leong YQ, Lee SWH, Ng KY

Eur J Neurol, 2021 Dec;28(12):4219-4237.
PMID: 34403556 DOI: 10.1111/ene.15069

BACKGROUND AND PURPOSE: Increasing evidence suggests significant associations between Parkinson disease (PD) and cancer risks. We conducted an updated review of studies that examined the risks of various cancer among PD patients and how this differed when cancer preceded PD diagnosis or PD diagnosis preceded cancer.
METHODS: Four databases were searched for studies that examined the association between PD and incidence of cancer from database inception to 4 June 2021. Three independent reviewers screened the articles for eligibility and extracted study data. Pooled relative risk with 95% confidence intervals were calculated using a random effects model.
RESULTS: Forty studies involving 11 case-control studies, two nested case-control studies, 22 cohort studies, and five cross-sectional studies were included. Compared to controls, PD patients had lower risks of lung, genitourinary, gastrointestinal, and haematological cancers. Conversely, higher risks of melanoma and brain cancer were noted among PD patients. No association was found between PD and risk of female cancers. Subgroup analysis found negative associations between PD patients and risks of colon cancer, rectal cancer, and non-Hodgkin lymphoma.
CONCLUSIONS: Findings from our meta-analysis suggest PD patients had lower risks of lung, genitourinary, gastrointestinal, and haematological cancers and increased risks of melanoma and brain cancer. Future research to investigate the underlying mechanisms between PD and cancers is warranted.
Potential role of melatonin in prevention and treatment of leukaemia

Ng MG, Ng KY, Koh RY, Chye SM

Horm Mol Biol Clin Investig, 2021 Aug 06;42(4):445-461.
PMID: 34355548 DOI: 10.1515/hmbci-2021-0009

Leukaemia is a haematological malignancy originated from the bone marrow. Studies have shown that shift work could disrupt the melatonin secretion and eventually increase leukaemia incidence risk. Melatonin, a pineal hormone, has shown promising oncostatic properties on a wide range of cancers, including leukaemia. We first reviewed the relationship between shift work and the incidence rate of leukaemia and then discussed the role of melatonin receptors (MT1 and MT2) and their functions in leukaemia. Moreover, the connection between inflammation and leukaemia, and melatonin-induced anti-leukaemia mechanisms including anti-proliferation, apoptosis induction and immunomodulation are comprehensively discussed. Apart from that, the synergistic effects of melatonin with other anticancer compounds are also included. In short, this review article has compiled the evidence of anti-leukaemia properties displayed by melatonin and discuss its potential to act as adjunct for anti-leukaemia treatment. This review may serve as a reference for future studies or experimental research to explore the possibility of melatonin serving as a novel therapeutic agent for leukaemia.
Role of the gut microbiome in Alzheimer's disease

Chok KC, Ng KY, Koh RY, Chye SM

Rev Neurosci, 2021 11 25;32(7):767-789.
PMID: 33725748 DOI: 10.1515/revneuro-2020-0122

Alzheimer's disease (AD) is the most common form of dementia, affecting millions of individuals each year and this number is expected to significantly increase. The complicated microorganisms residing in human gut are closely associated with our health. Emerging evidence has suggested possible involvement of human gut microbiome in AD. Symbiotic gut microbiomes are known to maintain brain health by modulating host's barriers integrity, metabolic system, immune system, nervous system and endocrine system. However, in the event of gut dysbiosis and barriers disruption, gut pathobionts disrupt homeostasis of the metabolic system, immune system, nervous system, and endocrine system, resulting in deterioration of neurological functions and subsequently promoting development of AD. Multiple therapeutic approaches, such as fecal microbiome transplant, antibiotics, prebiotics, probiotics, symbiotic, and diet are discussed as potential treatment options for AD by manipulating the gut microbiome to reverse pathological alteration in the systems above.
Digital health use in latent tuberculosis infection care: A systematic review

Wong YJ, Ng KY, Lee SWH

Int J Med Inform, 2022 Jan 05;159:104687.
PMID: 35007924 DOI: 10.1016/j.ijmedinf.2022.104687

PURPOSE: With one-quarter of the world's population estimated to have latent tuberculosis infection (LTBI), it is important that the drop-outs from the LTBI cascade of care are minimized. Digital health technology could play an important role in case detection and treatment adherence. This study aims to evaluate the use and impact of digital health technology in LTBI care.
METHODS: A systematic literature search was conducted on six electronic databases from database inception until May 31st 2021. Studies that reported on the clinical use or economic analysis of digital health technology for LTBI care were included. Two investigators independently evaluated, extracted relevant studies, and assessed the risk of bias of using the Cochrane tools. The studies were synthesized qualitatively.
RESULTS: Fifteen articles describing 14 studies were included. Voice and/or textual reminders and synchronous video call to improve LTBI treatment adherence were the most commonly examined digital health interventions. Other interventions examined the use of mobile phones to improve the number of patients who returned for tuberculin skin test follow-up measurement (screening retention) and eLearning videos to enhance health literacy in LTBI care. The economic analysis supported the use of textual reminders in LTBI treatment as a cost-effective option for widescale implantation.
CONCLUSIONS: Despite limited evidence on the effects of digital health technologies in LTBI, available studies suggest they are at least equivalent to current practice. This means digital health can potentially supplement current practice, to constantly monitor and engage with people undergoing LTBI screening or treatment, as an initiative to ensure the provision of continuous and optimal care to all LTBI-affected individuals.
Single-chain Fv Antibodies for Targeting Neurodegenerative Diseases

Chia KY, Ng KY, Koh RY, Chye SM

CNS Neurol Disord Drug Targets, 2018;17(9):671-679.
PMID: 29546836 DOI: 10.2174/1871527317666180315161626

BACKGROUND & OBJECTIVE: Protein misfolding and aggregation have been considered the common pathological hallmarks for a number of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). These abnormal proteins aggregates damage mitochondria and induce oxidative stress, resulting in neuronal cell death. Prolonged neuronal damage activates microglia and astrocytes, development of inflammation reaction and further promotes neurodegeneration. Thus, elimination of abnormal protein aggregates without eliciting any adverse effects are the main treatment strategies. To overcome this, recent studies have deployed single- chain fragment variable antibodies (scFvs) to target the pathological protein aggregates, such as amyloid-beta (Aβ) peptides, α-synuclein (α-syn) and Huntingtin (Htt). To date scFv has been effective at inhibiting abnormal protein aggregates formation in both in vitro and in vivo model system of AD, PD and HD.
CONCLUSION: Currently active research is still ongoing to improve the scFv gene delivery technology, to further enhance brain penetration, intracellular stability, solubility and efficacy of scFv intrabody.
Community pharmacists-led interventions in tuberculosis care: A systematic review

Wong YJ, Ng KY, Lee SWH

Res Social Adm Pharm, 2023 Jan;19(1):5-15.
PMID: 36096865 DOI: 10.1016/j.sapharm.2022.09.001

BACKGROUND: A multidisciplinary approach is required to tackle the tuberculosis (TB) epidemic, which is one of the most pressing public health concerns worldwide. However, community pharmacists are underutilized in TB programs.
OBJECTIVE: To identify community pharmacists-led interventions in TB management with their corresponding impacts in TB case detection and treatment outcomes.
METHODS: A systematic search was performed in six electronic databases and health organization websites, from database inception to August 2, 2022. Studies which described TB screening, referral and/or treatment monitoring by community pharmacists with their corresponding outcomes were screened and reviewed independently by two reviewers. The studies were checked for the risk of bias using Cochrane risk of bias tools. All data of included studies were analysed qualitatively and presented narratively.
RESULTS: The search yielded 8,121 studies and five reports for initial screening. Sixteen studies and two case study reports were included in this review. Community pharmacists were involved throughout the TB care cascade, contributing their services in TB screening, referrals and in directly observed treatment-short course (DOTS) program. These interventions showed improvements in the effective control and prevention of further spread of TB, which improves individual, community and population level outcomes.
CONCLUSIONS: The inclusion of community pharmacists into TB program can improve the continuity of care, bridging the gaps in TB case detection and treatment monitoring. Adequate training and support are essential, to further empower the role of community pharmacists in TB control and prevention, in building a TB-free world.
Fulltext Exploring changes in guest preferences for Airbnb accommodation with different levels of sharing and prices: Using structural topic model

Ding K, Choo WC, Ng KY, Zhang Q

Front Psychol, 2023;14:1120845.
PMID: 36874802 DOI: 10.3389/fpsyg.2023.1120845

INTRODUCTION: Online reviews have become an important source of information for investigating customers' consumption experiences in academic studies. In the context of sharing economy-based accommodation, various studies have been conducted to investigate the user experience of Airbnb by analyzing online reviews; however, most previous Airbnb studies had focused on analyzing the user experience of Airbnb at a holistic level without distinguishing the accommodation attributes of Airbnb. Therefore, this article aimed to investigate how the preferences revealed by Airbnb users in online reviews vary across Airbnb listings with different levels of sharing and price ranges.
METHODS: This study analyzed 181,190 online reviews under Airbnb listings in Kuala Lumpur, Malaysia, using the structural topic model (STM).
RESULTS: This study identified 21 topics related to Airbnb service and product attributes.
DISCUSSION: The findings show that Airbnb users who stay at entire property are more concerned with the hedonic value of their stay, while those who stay at shared property are more concerned with the utilitarian value. The purposes of the host-guest interaction were also found to differ between these two types of Airbnb accommodations. Regarding the effect of listing prices on users' preferences, findings reveal that those staying at lower-priced rooms were more concerned about the convenience of exploring the surrounding area, while those who stayed at higher-priced rooms were more concerned about the surrounding environment and the interior facilities of the property.
Engaging community pharmacists in tuberculosis-directly observed treatment: a mixed-methods study

Wong YJ, Thum CC, Ng KY, Lee SWH

Prim Health Care Res Dev, 2023 Mar 22;24:e21.
PMID: 36946302 DOI: 10.1017/S1463423623000105

AIM: This study aimed to evaluate the feasibility of implementing community pharmacy-based tuberculosis-directly observed treatment (TB-DOT) in Malaysia.
BACKGROUND: Tuberculosis (TB) eradication is one of the top priorities in the public health agenda in Malaysia. While public-private mix (PPM) initiatives have been launched, community pharmacists remain undervalued assets in TB management.
METHODS: A two-phase mixed-methods study targeting community pharmacists was conducted in Malaysia between March and October 2021. The first phase was an online self-administered survey developed according to the Consolidated Framework for Implementation Research (CFIR). The second phase was a semi-structured interview to allow deeper understanding on the quantitative results. Quantitative data were analysed using descriptive analysis while qualitative data were analysed using thematic analysis with a semi-inductive approach. The data were triangulated to enhance comprehensiveness and credibility of the findings.
FINDINGS: The survey was completed by 388 community pharmacists, and 23 pharmacists participated in the interview. Most community pharmacists indicated their willingness to serve as TB-DOT supervisors (70.1%). Qualitative results supported the findings. Community pharmacy-based TB-DOT service was perceived as an avenue to improve TB management and outcomes and to enhance the professional role of pharmacists in TB service at primary care settings. This was also perceived as a feasible intervention with the potential to strengthen the National TB Control programme. This initiative needs be reinforced with adequate support from the public healthcare sector for a strong partnership in ensuring success.
Fulltext Unravelling the genetic links between Parkinson's disease and lung cancer

Leong YQ, Koh RY, Chye SM, Ng KY

Biol Chem, 2023 May 25;404(6):551-567.
PMID: 36634094 DOI: 10.1515/hsz-2022-0228

Increase evidence from epidemiological studies have shown an inverse association between Parkinson's disease (PD) and lung cancer. PD and lung cancer are both geriatric diseases, where these two diseases are sharing some common genetic determinants. Several PD-associated genes including alpha synuclein (SNCA), PTEN-induced kinase 1 (PINK1), parkin, parkinsonism associated deglycase (DJ-1), leucine-rich repeat kinase 2 (LRRK2), F-box protein 7 (FBXO7) and ubiquitin C-terminal hydrolase L1 (UCHL1) were reported to have altered expressions in lung cancer patients. This indicates that certain PD-associated genes might be important in conferring anticancer effects. This review aims to depict the physiological functions of these genes, and discuss the putative roles of these PD-associated genes in lung cancer. The understanding of the roles of these genes in the lung cancer progression might be important in the identification of new treatment targets for lung cancer. Gene therapy that aims to alter the expressions of these genes could be developed for future anticancer therapy. As a result, studying the roles of these genes in lung cancer may also help to understand their involvements as well as their roles in the pathogenesis of PD.

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