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Fulltext Effects of salvianolic acid A on β-amyloid mediated toxicity in Caenorhabditis elegans model of Alzheimer's disease

Yuen CW,, Halim MA,, Najimudin N,, Azzam G,

Journal of Biomedical and Clinical Sciences, 2020;5(1):1-7.
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Alzheimer’s disease (AD) is a brain disease attributed to the accumulation of extracellular senile plaques comprising β-amyloid peptide (Aβ). In this study, a transgenic Caenorhabditis elegans (C. elegans) containing the human beta amyloid Aβ42 gene which exhibited paralysis when expressed, was used to study the anti-paralysis effect of salvianolic acid A. Various concentrations ranging from 1 μg/ml to 100 μg/ml of salvianolic acid A were tested which exhibited the highest effect on the worm at the concentration of 100 μg/ml. For anti-aggregation effect, 14 μg/ml of salvianolic acid A (within 4 mg/ml of Danshen) showed a significant level of inhibition of the formation of Aβ fibrils. An amount of 100 μg/ml of salvianolic acid A had the potential in reducing the reactive oxygen species (ROS) but did not totally obliterate the ROS production in the worms. Salvianolic acid A was found to delay the paralysis of the transgenic C. elegans, decrease Aβ42 aggregation and decrease Aβ-induced oxidative stress.
Fulltext Analysis of motorcyclist riding behaviour on speed table

Yuen CW, Karim MR, Saifizul A

ScientificWorldJournal, 2014;2014:236396.
PMID: 24991638 DOI: 10.1155/2014/236396

This paper focuses on the study of the change of various types of riding behaviour, such as speed, brake force, and throttle force applied, when they ride across the speed table. An instrumented motorcycle equipped with various types of sensor, on-board camera, and data logger was used in acquiring the traffic data in the research. Riders were instructed to ride across two speed tables and the riding data were then analyzed to study the behaviour change from different riders. The results from statistical analysis showed that the riding characteristics such as speed, brake force, and throttle force applied are influenced by distance from hump, riding experience, and travel mileage of riders. Riders tend to apply higher brake intensity at distance point 50 m before the speed table and release the braking at point -10 m after the hump. In short, speed table has different rates of influence towards riding behaviour on different factors, such as distance from hump and different riders' attributes.
Fulltext Investigation on motorcyclist riding behaviour at curve entry using instrumented motorcycle

Yuen CW, Karim MR, Saifizul A

ScientificWorldJournal, 2014;2014:968946.
PMID: 24523660 DOI: 10.1155/2014/968946

This paper details the study on the changes in riding behaviour, such as changes in speed as well as the brake force and throttle force applied, when motorcyclists ride over a curve section road using an instrumented motorcycle. In this study, an instrumented motorcycle equipped with various types of sensors, on-board cameras, and data loggers, was developed in order to collect the riding data on the study site. Results from the statistical analysis showed that riding characteristics, such as changes in speed, brake force, and throttle force applied, are influenced by the distance from the curve entry, riding experience, and travel mileage of the riders. A structural equation modeling was used to study the impact of these variables on the change of riding behaviour in curve entry section. Four regression equations are formed to study the relationship between four dependent variables, which are speed, throttle force, front brake force, and rear brake force applied with the independent variables.
Fulltext Using simulation model as a tool for analyzing bus service reliability and implementing improvement strategies

Moosavi SMH, Ismail A, Yuen CW

PLoS One, 2020;15(5):e0232799.
PMID: 32379848 DOI: 10.1371/journal.pone.0232799

Bus services naturally tend to be unstable and are not always capable of adhering to schedules without control strategies. Therefore, bus users and bus service providers face travel time variation and irregularity. After a comprehensive review of the literature, a significant gap was recognized in the field of public transportation reliability. According to literature, there is no consistency in reliability definition and indicators. Companies have their own definition of bus service reliability, and they mostly neglect the passengers' perspective of reliability. Therefore, four reliability indicators were selected in this study to fill the gap in the literature and cover both passengers' and operators' perceptions of reliability: waiting time and on-board crowding level from passengers' perspective, and headway regularity index at stops (HRIS) and bus bunching/big gap percentage from operators' perspective. The primary objective of this research is to improve the reliability of high frequency of bus service and simulation tools currently being used by the public transportation companies. Therefore, a simulation model of bus service was developed to study the strategies to alleviate it. Four different types of strategies were selected and implemented according to Route U32 (Kuala Lumpur) specifications. Model out-put showed that control strategies such as headway-based dispatching could significantly improve headway regularity by almost 62% and the waiting time by 51% on average. Both holding strategies at key stops (previous and Prefol holding) have shown an almost similar impact on reliability indicators. Waiting time was reduced by 44% and 43% after the previous and Prefol Headway strategies were adopted, respectively. However, the implementation of the component of headway-based strategies at the terminal and key stops showed the best impact on reliability, in terms of passenger waiting time. Waiting time and excess waiting time were both significantly reduced by 52.86% and 81.44%, respectively. Nevertheless, the strategies did not show any significant positive effect on the level of crowding during morning peak hours.
The Effectiveness of Educational Intervention in Improving Primary Health-Care Service Providers' Knowledge, Identification, and Management of Elder Abuse and Neglect: A Systematic Review

Mydin FHM, Yuen CW, Othman S

Trauma Violence Abuse, 2021 10;22(4):944-960.
PMID: 31823685 DOI: 10.1177/1524838019889359

Elder abuse and neglect (EAN) occurrence is expected to increase in many countries due to rapidly aging populations, yet it is still unrecognized and underreported. Gaps were identified in the knowledge and skills to intervene EAN among health-care service providers. It is still unclear whether educating health-care service providers on EAN improve the identification and management of EAN cases. A systematic review was conducted on the effectiveness of educational intervention designed to improve primary health-care service providers' (PHSPs) knowledge, attitude, and practice in managing EAN cases. We performed a comprehensive and systematic search for original studies in the following major electronic databases (ScienceDirect, PubMed, EMBASE, and CINAHL) and specialist registers (Cochrane Central Controlled Trials Register) with a set of search terms. Studies included were randomized controlled trials (RCTs) and observational studies on EAN education intervention that aimed to improve knowledge, attitude, and management skills of the PHSPs. There were no publication period restrictions until June 2018 and written in English. Overall, three RCTs and 10 observational studies were selected. These studies were grouped based on the type of the study, methodological quality (six moderate risk of bias and seven serious risk of bias), and the type of educational intervention (seven face-to-face educational intervention, two educational videos, two simulation-based training, and two online educational training). The education programs in the selected studies range from brief didactic to experiential learning. EAN educational intervention among primary care service providers potentially result in increasing awareness and knowledge on EAN. However, there is a lack of evidence on the changes of attitude and practice.
Fulltext Improvement of trip generation rates for mixed-use development in Klang Valley, Malaysia

Goh BH, Yuen CW, Onn CC

Sci Rep, 2023 Feb 15;13(1):2699.
PMID: 36792761 DOI: 10.1038/s41598-023-29748-w

Mixed-use developments (MXDs) are a single development project that integrates and interacts with different land uses. Traffic is estimated to be reduced with such development. However, there is no standard procedure is available to estimate the MXD trip generation rates in Malaysia. The Malaysian Trip Generation Manual (MTGM) is the guidelines currently been used to forecast future trips for single land use. If the trip generation rates for multiple land uses are summed as MXD trips, the total trips will be overestimated without considering the internal trip capture. This study aimed to establish an improved method for estimating the MXD trip generation rates. Four MXD observation sites were selected in Klang Valley. Traffic survey counts were conducted considering person-trip, including passengers in vehicles and pedestrians. The results revealed that the MXD trip generation rates with MTGM were higher than actual traffic counts during peak hours. The MXD adjustment factor was established as 0.63, which can be applied by multiplying the MTGM trip generation rates to reduce the generated MXD trips in PCU per hour. This research has formulated a new data collection method by integrating person counts, alongside with new guidelines for pedestrian counts. The findings provide an option to adjust the MXD trips and prevent from overestimating future trips, which may result in overdevelopment and spending on mitigation measures in urban planning and road infrastructure.
Danshen (Salvia miltiorrhiza) water extract shows potential neuroprotective effects in Caenorhabditis elegans

Yuen CW, Murugaiyah V, Najimudin N, Azzam G

J Ethnopharmacol, 2021 Feb 10;266:113418.
PMID: 32991971 DOI: 10.1016/j.jep.2020.113418

ETHNOPHARMACOLOGICAL RELEVANCE: Danshen, is a traditional Chinese medicine obtained from the dried root and rhizome of Salvia miltiorrhiza Bunge. It is known to be used for neurological disorder including for Alzheimer's disease (AD). This study uncovers the effect of Danshen water extract on the Alzheimer's disease model of C.elegans.
MATERIAL AND METHODS: The composition of Danshen water extract was determined using (High Performance Liquid Chromatography (HPLC). Then Thioflavin T assay was used to determined if Danshen water extract could prevent the aggregation of amyloid-β peptide (Aβ). Alzheimer's disease C.elegans model was used to determine the effect of Danshen water extract. Finally, the reactive oxygen species (ROS) was determined using the 2,7-dichlorofuorescein diacetate method.
RESULTS: In this study, we found that standardized Danshen water extract that contains danshensu (1.26%), salvianolic acid A (0.35%) and salvianolic acid B (2.21%) are able to bind directly to Aβ and prevents it from aggregating. The IC50 for the inhibition of Aβ aggregation by Danshen water extract was 0.5 mg/ml. In the AD model of C.elegans, Danshen water extract managed to alleviates the paralysis phenotype. Furthermore, the administration of Danshen water extract displayed antioxidant properties toward the Aβ-induced oxidative stress.
CONCLUSIONS: AD is a widespread neurodegenerative disease attributed to the accumulation of extracellular plaques comprising Aβ. Danshen water extract could significantly reduce the progress of paralysis in the AD model of C. elegans, showing promising results with its antioxidant properties. It can be concluded that Danshen water extract could potentially serve as a therapeutic for AD.
Exploring Intimate Partner Violence Among Women Attending Malaysian Primary Care Clinics

Othman S, Yuen CW, Mohd Zain N, Abdul Samad A

J Interpers Violence, 2021 08;36(15-16):NP7920-NP7941.
PMID: 30938233 DOI: 10.1177/0886260519839426

Victims of intimate partner violence (IPV) are frequent attendees at health care facilities. Although most literature on this subject focuses on developed or Western countries, there is a dearth of information from Asian countries. This study aims to estimate the prevalence of IPV among women attending urban primary care services in Malaysia and to identify the risk factors associated with IPV. Six out of 15 available public primary care clinics in the federal territory of Kuala Lumpur, Malaysia, were randomly selected. The sampling size for each clinic was conducted proportionate to the clinic's average daily patient attendance. A total of 882 women participated in this study via a self-administered questionnaire. We administered the women's experience with battering scale (WEB-scale) to estimate the prevalence of psychological violence and included a screening question for physical and sexual assault. The results showed that 22.0% of the women surveyed reported experiencing IPV. Ethnicity appears to be a significant predictor, with Chinese and Indian women reporting IPV at a higher rate than Malay women. Women with IPV are more likely to come from lower income households, have witnessed parental IPV, receive less social support, and have poorer psychological well-being. Our findings indicate that the prevalence of IPV among women attending urban public primary care clinics is high. Health care providers should pay close attention during clinical encounters for any sign of IPV, particularly among those presenting with risk factors.
Construction and characterization of a Burkholderia pseudomallei wzm deletion mutant

Yuen CW, Ong EB, Mohamad S, Manaf UA, Najimudin N

J Microbiol Biotechnol, 2012 Oct;22(10):1336-42.
PMID: 23075783

In Burkholderia pseudomallei, the pathogen that causes melioidosis, the gene cluster encoding the capsular polysaccharide, is located on chromosome 1. Among the 19 capsular genes in this cluster, wzm has not been thoroughly studied. To study the function of wzm, we generated a deletion mutant and compared it with the wild-type strain. The mutant produced less biofilm in minimal media and was more sensitive to desiccation and oxidative stress compared with the wild-type strain, indicating that wzm is involved in biofilm formation and membrane integrity. Scanning electron microscopy showed that the bacterial cells of the mutant strain have more defined surfaces with indentations, whereas cells of the wild-type strain do not.
Fulltext Aerogel and expanded perlite incorporated lightweight cementitious composites containing crushed glass: Evaluation of the drying shrinkage and alkali-silica expansion

Shah SN, Tan TH, Tey OW, Leong GW, Chin YS, Yuen CW, et al.

Sci Prog, 2022;105(2):368504221091186.
PMID: 35379044 DOI: 10.1177/00368504221091186

Lightweight cementitious composite (LCC) produced by incorporating lightweight silica aerogel was explored in this study. Silica aerogel was incorporated as 60% replacement of fine aggregate (sand/crushed glass) in producing the LCC. The effect of aerogel on the drying shrinkage and alkali-silica expansion of LCC was evaluated and compared with those of lightweight expanded perlite aggregate. At the density of 1600 ± 100 kg/m3, the aerogel/ expanded perlite LCC had attained compressive strength of about 17/24 MPa and 22/26 MPa in mixtures with sand and crushed glass as a fine aggregate, respectively. The inclusion of aerogel and expanded perlite increased the drying shrinkage. The drying shrinkage of aerogel LCC was up to about 3 times of the control mixtures. Although the presence of aerogel and expanded perlite could reduce the alkali-silica expansion when partially replacing crushed glass, the aerogel-glass LCC still recorded expansion exceeding the maximum limit of 0.10% at 14 days. However, when 15% cement was replaced with fly ash and granulated blast furnace slag, the alkali-silica expansion was reduced to 0.03% and 0.10%, respectively. Microstructural observations also revealed that the aerogel with fly ash can help in reducing the alkali-silica expansion in mixes containing the reactive crushed glass aggregate.