Displaying all 9 publications

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  1. Chee CS, Tan IK, Alias Z
    ScientificWorldJournal, 2014;2014:750317.
    PMID: 24892084 DOI: 10.1155/2014/750317
    Glutathione transferases (GST) were purified from locally isolated bacteria, Acinetobacter calcoaceticus Y1, by glutathione-affinity chromatography and anion exchange, and their substrate specificities were investigated. SDS-polyacrylamide gel electrophoresis revealed that the purified GST resolved into a single band with a molecular weight (MW) of 23 kDa. 2-dimensional (2-D) gel electrophoresis showed the presence of two isoforms, GST1 (pI 4.5) and GST2 (pI 6.2) with identical MW. GST1 was reactive towards ethacrynic acid, hydrogen peroxide, 1-chloro-2,4-dinitrobenzene, and trans,trans-hepta-2,4-dienal while GST2 was active towards all substrates except hydrogen peroxide. This demonstrated that GST1 possessed peroxidase activity which was absent in GST2. This study also showed that only GST2 was able to conjugate GSH to isoproturon, a herbicide. GST1 and GST2 were suggested to be similar to F0KLY9 (putative glutathione S-transferase) and F0KKB0 (glutathione S-transferase III) of Acinetobacter calcoaceticus strain PHEA-2, respectively.
  2. Chee CS, Do Ha I, Seo B, Lee Y
    Stat Methods Med Res, 2021 Nov;30(11):2485-2502.
    PMID: 34569366 DOI: 10.1177/09622802211037072
    A consequence of using a parametric frailty model with nonparametric baseline hazard for analyzing clustered time-to-event data is that its regression coefficient estimates could be sensitive to the underlying frailty distribution. Recently, there has been a proposal for specifying both the baseline hazard and the frailty distribution nonparametrically, and estimating the unknown parameters by the maximum penalized likelihood method. Instead, in this paper, we propose the nonparametric maximum likelihood method for a general class of nonparametric frailty models, i.e. models where the frailty distribution is completely unspecified but the baseline hazard can be either parametric or nonparametric. The implementation of the estimation procedure can be based on a combination of either the Broyden-Fletcher-Goldfarb-Shanno or expectation-maximization algorithm and the constrained Newton algorithm with multiple support point inclusion. Simulation studies to investigate the performance of estimation of a regression coefficient by several different model-fitting methods were conducted. The simulation results show that our proposed regression coefficient estimator generally gives a reasonable bias reduction when the number of clusters is increased under various frailty distributions. Our proposed method is also illustrated with two data examples.
  3. Chee CS, Chang KM, Loke MF, Angela Loo VP, Subrayan V
    PeerJ, 2016;4:e2022.
    PMID: 27280065 DOI: 10.7717/peerj.2022
    AIM/HYPOTHESIS: The aim of our study was to characterize the human salivary proteome and determine the changes in protein expression in two different stages of diabetic retinopathy with type-2 diabetes mellitus: (1) with non-proliferative diabetic retinopathy (NPDR) and (2) with proliferative diabetic retinopathy (PDR). Type-2 diabetes mellitus without diabetic retinopathy (XDR) was designated as control.
    METHOD: In this study, 45 saliva samples were collected (15 samples from XDR control group, 15 samples from NPDR disease group and 15 samples from PDR disease group). Salivary proteins were extracted, reduced, alkylated, trypsin digested and labeled with an isobaric tag for relative and absolute quantitation (iTRAQ) before being analyzed by an Orbitrap fusion tribrid mass spectrometer. Protein annotation, fold change calculation and statistical analysis were interrogated by Proteome Discoverer. Biological pathway analysis was performed by Ingenuity Pathway Analysis. Data are available via ProteomeXchange with identifiers PXD003723-PX003725.
    RESULTS: A total of 315 proteins were identified from the salivary proteome and 119 proteins were found to be differentially expressed. The differentially expressed proteins from the NPDR disease group and the PDR disease group were assigned to respective canonical pathways indicating increased Liver X receptor/Retinoid X receptor (LXR/RXR) activation, Farnesoid X receptor/Retinoid X receptor (FXR/RXR) activation, acute phase response signaling, sucrose degradation V and regulation of actin-based motility by Rho in the PDR disease group compared to the NPDR disease group.
    CONCLUSIONS/INTERPRETATION: Progression from non-proliferative to proliferative retinopathy in type-2 diabetic patients is a complex multi-mechanism and systemic process. Furthermore, saliva was shown to be a feasible alternative sample source for diabetic retinopathy biomarkers.
  4. Li R, Chee CS, Kamalden TF, Ramli AS, Yang K
    J Sports Med Phys Fitness, 2024 Jan;64(1):55-65.
    PMID: 37902798 DOI: 10.23736/S0022-4707.23.15220-0
    INTRODUCTION: Blood flow restriction training (BFRT) is an effective training method to improve sports performance in healthy athletes. Nevertheless, a systematic review with meta-analysis regarding how BFRT affects sports performance in athletes is still lacking. Consequently, the study attempted to expand and consolidate the prior studies regarding the effect of BFRT on technical and physical performance in athletes.

    EVIDENCE ACQUISITION: This study was based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyzes) statement guidelines for a systematic review of the academic databases Scopus, Web of Science, PubMed, EBSCOhost (SportDiscus), and Google Scholar. The PEDro scale was used to assess the methodological quality of the included publications, which ranged from moderate to high quality. The systematic review protocol was registered on inplasy.com (INPLASY202380049).

    EVIDENCE SYNTHESIS: Out of 249 studies identified, 93 articles were evaluated as eligible, and after the screening, 18 studies were finally included in this systematic review. Meta-analysis results showed a significant enhancement on vertical jump height in the BFRT group compared to the control group (SMD=1.39, 95% CI=0.30-2.49, P=0.01). BFRT was able to significantly increase maximal oxygen uptake (SMD=1.65, 95% CI=0.56-2.74, P<0.01). While no significant improvement in sprint time was observed (SMD= -0.18, 95% CI=-1.18-0.82, P=0.115).

    CONCLUSIONS: The finding suggests that BFRT is beneficial to athletes as this training method can be effective in enhancing physical and technical performance in athletes. Nevertheless, further analysis needs to be conducted to fully determine the effectiveness of the moderators of the intervention on sports performance.

  5. Yang K, Chee CS, Abdul Kahar J, Tengku Kamalden TF, Li R, Qian S
    Sci Rep, 2024 Jul 18;14(1):16615.
    PMID: 39025894 DOI: 10.1038/s41598-024-67181-9
    Blood flow restriction training (BFRT) is an effective, scientific and safe training method, but its effect on the overall quality of athletes remains unclear. The aim of this systematic review with meta-analysis was to clarify the effects of BFRT on the physical fitness among athletes. Based on the PRISMA guidelines, searches were performed in PubMed, Web of Science, SPORTDiscus, and SCOUPS, the Cochrane bias risk assessment tool was used to assess methodological quality, and RevMan 5.4 and STATA 15.0 software were used to analyze the data. A meta-analysis of 28 studies with a total sample size of 542 athletes aged 14-26 years and assessed as low risk for quality was performed. Our results revealed that the BFRT intervention had small to large improvements in the athletes' strength (ES = 0.74-1.03), power (ES = 0.46), speed (ES = 0.54), endurance (ES = 1.39-1.40), body composition (ES = 0.28-1.23), while there was no significant effect on body mass (p > 0.05). Subgroup analyses revealed that moderator variables (training duration, frequency, load, cuff pressure, and pressurization time) also had varying degrees of effect on athletes' physical fitness parameters. In conclusion, BFRT had a positive effect on the physical fitness parameters of the athletes, with significantly improved strength, power, speed, endurance and body composition, but not body mass parameters. When the training frequency ≥ 3 times/week, cuff pressure ≥ 160 mmHg, and pressurization time ≥ 10 min, the BFRT group was more favorable for the improvement of physical fitness parameters.
  6. Gao Z, Chee CS, Norjali Wazir MRW, Wang J, Zheng X, Wang T
    Front Psychol, 2023;14:1291711.
    PMID: 38259527 DOI: 10.3389/fpsyg.2023.1291711
    OBJECTIVES: Parents are one of the main social agents that shape young athletes' experiences and participation in sports, but they are also the least explored group in the literature. Therefore, the purpose of this study was to conduct a systematic review of research on the role of parents in the motivation of young athletes.

    METHOD: The systematic literature review consisted of four electronic databases from which 29 articles published in English and in full-text form in peer-reviewed journals between 1999 and 2023 were retrieved.

    RESULTS: A total of 29 studies met the eligibility criteria. These studies collectively surveyed 9,185 young athlete participants and 2,191 parent participants. The sample comprised 26 quantitative studies and 3 qualitative studies. The findings underscore that parents play both unique and synergistic multidimensional roles in motivating young athletes. Parents' positive goals and values, autonomy-supportive parenting styles, moderate parental involvement, positive parent-child relationships, and a parent-initiated task climate are identified as optimal parenting strategies.

    CONCLUSION: While parents undeniably play a crucial role in motivating young athletes, the manner and extent of their involvement are key.

  7. Gao Z, Chee CS, Dev RDO, Li F, Li R, Gao J, et al.
    PLoS One, 2024;19(11):e0314610.
    PMID: 39602461 DOI: 10.1371/journal.pone.0314610
    College and university students often exhibit insufficient levels of physical activity, which negatively impacts their health, mental well-being, and academic performance. Social capital has emerged as a potential factor in promoting physical activity. This systematic review, conducted in line with PRISMA guidelines, examines the existing literature on the role of social capital in enhancing physical activity among college and university students. A search of the Web of Science, Scopus, SportDiscus, and PsychINFO databases identified 10 studies published by August 1, 2024, involving 2,700 students, primarily from North America and Europe. The overall quality of the included studies was high, with all scoring above 85% on quality assessments. The findings indicate that social capital, particularly strong social networks, support from family and friends, and high levels of social cohesion, is significantly associated with higher levels of physical activity among college and university students. Social capital may facilitate physical activity in group settings through mechanisms such as emotional support, role modeling, and social norms. Despite limitations within the existing research evidence, such as reliance on self-reported data and cross-sectional study designs, this review suggests that social capital holds potential for promoting physical activity in this population. Future research should prioritize the use of objective measurement tools and longitudinal designs to more accurately assess the long-term effects of social capital and explore how these findings can inform effective interventions.
  8. Ma L, Chee CS, Amri S, Gao X, Wang Q, Wang N, et al.
    PeerJ, 2025;13:e18952.
    PMID: 39995991 DOI: 10.7717/peerj.18952
    BACKGROUND: The professional development of teachers in the digital age will positively impact the effectiveness of physical education teaching. Exploring key factors such as self-efficacy, burnout, and digital technology is crucial to ensure the professional development of teachers.

    METHODS: The search was conducted in accordance with the PRISMA guidelines and utilized the following databases: Scopus, Web of Science, ProQuest, and Google Scholar. Inclusion and exclusion criteria: population, research methods, keywords, and time limit were described for this study. This article predominantly includes cross-sectional studies, so we have used the AXIS risk assessment methodology.

    RESULTS: The study included ten articles, seven of which (70%) were quantitative. Three key findings emerged from this review: first, the studies on self-efficacy were more noteworthy than the studies on burnout. Second, female teachers were more expressive in their digital teaching, while male teachers had higher levels of self-efficacy in their digital teaching. Finally, the study explored various factors affecting self-efficacy and burnout in relation to digital teaching. The study demonstrated that professional development has a higher impact on physical education teachers' self-efficacy, and in turn, self-efficacy reduces burnout. Additionally, burnout had a significant impact on professional development.

    CONCLUSION: This study describes the limitations of risk assessment and uses the AXIS tool to assess the methodological quality of this review report instead of using the risk of bias tool. The use of digital teaching methods can increase self-efficacy and alleviate burnout among physical education teachers. This review analyses the effects of digital technology, self-efficacy, and burnout on the career progression of physical education instructors and examines the implications for future developments.

  9. Gao Z, Chee CS, Omar Dev RD, Liu Y, Gao J, Li R, et al.
    Front Public Health, 2025;13:1467571.
    PMID: 40013056 DOI: 10.3389/fpubh.2025.1467571
    BACKGROUND: Social capital, as a multidimensional social science concept, plays a crucial role in promoting physical activity. Despite numerous studies exploring the relationship between social capital and physical activity, there is still a lack of systematic understanding of how different dimensions of social capital influence physical activity levels. This study aims to systematically review the literature up to 2024 on the relationship between social capital and physical activity, uncover the role of social capital in promoting physical activity, and identify its multidimensional impacts.

    METHODS: We used a combination of search terms including "social capital" and "physical activity" to search the Web of Science, PubMed, Scopus, SportDiscus, and PsychINFO databases for English literature published up to March 1, 2024.

    RESULTS: We identified 2,021 unique articles and reviewed 115 studies that met our inclusion criteria. These studies evaluated various dimensions of social capital, with key dimensions including social participation (34%), social networks (30%), social cohesion (30%), social trust (29%), overall social network (26%), social support (19%), safety (19%), norms of reciprocity (13%), social control (10%), satisfaction with the environment (8%), collective efficacy (4%), norms for physical activity (3%), and voting (1%). In studies exploring the relationship between social capital and physical activity, the majority of positive results in the hypothesized direction were observed in dimensions such as social cohesion, trust, participation, reciprocity, satisfaction with the environment, and overall social networks. In contrast, dimensions such as voting, collective efficacy, safety, control, and physical activity norms predominantly showed null or negative results. The results for social support were mixed, displaying positive, negative, and null outcomes, while findings for social networks were also predominantly mixed.

    CONCLUSION: This study reveals the significant role of social capital in promoting physical activity, particularly in the dimensions of social cohesion, social trust, social participation, norms of reciprocity, satisfaction with environment, and overall social network. When designing public health interventions in the future, it is crucial to tailor strategies to different populations and contexts to better leverage social capital in promoting physical activity.

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