John W Yuen

Dr. John W Yuen

SPECTRA MedComms & Research Consulting, St. Albert, Alberta, Canada
+1
orcid

Research Focus & Metrics

Academic Career Length

71Years (1956-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 September 2018 in BMC Public Health
Verified
Journal Article
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FWFiona Y. Wong
Fiona Y. Wong
LYLin Yang
Lin Yang
John W YuenJohn W Yuen
John W Yuen
KCKatherine Ka Pik Chang
Katherine Ka Pik Chang
FWFrances K.Y. Wong
Frances K.Y. Wong
Quality of life (QOL) is an important component in assessing people’s health. Environmental quality can influence people’s QOL in the physical health, psychological, social relationships and environment domains. QOL in the four domains, overall QOL and general heath of residents living in the Kowloon Peninsula of Hong Kong were assessed. The association between satisfaction with the neighborhood environment and QOL, and health-related behaviors which mediated the effect were investigated. A sample of 317 residents completed a questionnaire which comprised the WHOQOL-BREF (Hong Kong version) to assess QOL, the International Physical Activity Questionnaire (IPAQ) to study physical activities, and questions on satisfaction with the neighborhood environment, health-related behaviors and socio-demographics. One-way ANOVA and linear regression were used to study the associations between environmental satisfaction and QOL in the four domains, overall QOL and general health, followed by assessing the relationships between environmental satisfaction and the potential health-related behavior mediators with regression tests. Mediation analysis was conducted using multiple linear regressions to study the effects of environmental satisfaction on QOL in the four domains, overall QOL and general health, as well as the potential mediating roles played by various health-related behaviors. A P-value of < 0.05 was considered as statistically significant. The residents had a relatively higher physical health mean score of 70.83 ± 12.69, and a lower environmental mean score of 61.98 ± 13.76. Moderate satisfaction with the neighborhood environment had a significant relationship with QOL in the psychological domain (β = 0.170, P = 0.006), however, this effect was partially mediated by the non-smoking behavior of the residents (β = 0.143, P = 0.022). Our residents had lower QOL in the physical health and psychological domains but similar QOL in the social relationships and environmental domains compared to other countries. Only QOL in the psychological domain could be predicted by the satisfaction with the neighborhood environment, and non-smoking status was a partial mediator of the effect of moderate environmental satisfaction on QOL in the psychological domain. Refrain from smoking seems to be able to lower the influence of neighborhood environment on people’s QOL in the psychological domain to a certain extent.

1 September 2005 in Nutrition and Cancer
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John W YuenJohn W Yuen
John W Yuen
MGMayur Danny I. Gohel
Mayur Danny I. Gohel
"Lingzhi" (Ganoderma lucidum), a popular medicinal mushroom, has been used in China for longevity and health promotion since ancient times. Investigations into the anticancer activity of ...

1 January 2003 in Free Radical Research
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Journal Article
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John W YuenJohn W Yuen
John W Yuen
IBI. F. F. Benzie
I. F. F. Benzie
The level of hydrogen peroxide (H2O2) in urine has been suggested as a potential biomarker of whole body oxidative stress, but issues of stability, reproducibility and biological variation have not been investigated to date. In this study, we used a refined protocol, which demonstrated improved sensitivity and precision, to determine the stability of H2O2 in urine, and to measure its concentration in apparently healthy subjects. We also investigated intra-individual variation within and between days. Results showed that H2O2 in urine is stable for up to 48 h at 4 °C, however, storage of urine at room temperature was associated with up to 50% increase in H2O2 concentration over a few hours. Total H2O2 in freshly voided urine from 55 healthy, fasting subjects ranged from 0.84 to 5.71 µM, or 90-1164 µmol H2O2/mol creatinine. Intra-individual variation was wide. Even when concentration corrected and collected at the same time of day, 2- to 3-fold variation was seen over 4 consecutive days, and over the course of a single day the creatinine-corrected H2O2 also varied significantly. We suggest that this large biological variation limits the usefulness of urine H2O2 as a biomarker of oxidative stress, the exception being when the effects of disease, therapy or diet induce very large changes in its concentration.

KCKatherine Ka Pik Chang
Katherine Ka Pik Chang
FWFrances K.Y. Wong
Frances K.Y. Wong
KCKa Long Chan
Ka Long Chan
FWFiona Wong
Fiona Wong
HHHung Chak Ho
Hung Chak Ho
LYLin Yang
Lin Yang
(1) Background: Environment is an independent factor that affects one’s quality of life (QoL), where studies suggest that health behaviours also affect one’s quality of life. The purpose of the present study was to examine the association between environmental conditions and QoL and how individual health behaviours affect this association. (2) Methods: Participants aged 20 or above were recruited from 11 tertiary planning units in the central part of Kowloon. These tertiary planning units were selected as they represented the overall living environment in Hong Kong, with a mix of the poorer urban areas alongside relatively affluent districts. A mediation analysis was implemented using multiple linear regressions to examine the effects of environmental conditions on QoL. (3) Results: Of the 607 eligible participants included for analysis, 390 were female and 217 were male, with a mean age of 47.4 years. Living within 500 m of a green space area had benefits on the physical aspect of QoL and physical activity but no effect on the psychological aspect of QoL. Moderate satisfaction with public spaces affected QoL positively. In contrast, less satisfaction with public spaces affected QoL negatively in both physical and psychological aspects through the mediating effect of stress. Poor environmental quality affected all domains of QoL negatively through the mediating effects of increased stress and poor sleep. (4) Conclusions: Environment is an important factor that affects individuals’ overall well-being. The interaction between environmental conditions and individual variables, especially perceived stress and sleep, is extremely important when assessing its impact on QoL. The findings of this study support the importance of individual stress and sleep in mediating the relationship between the environment and QoL for health. Further studies should be conducted to include objective measurements, such as those of cortisol levels for stress and physical fitness tests.

1 July 2021 in Nature and Science of Sleep
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WYWing-Fai YEUNG
Wing-Fai YEUNG
Yee Man Branda YuYee Man Branda Yu
Yee Man Branda Yu
John W YuenJohn W Yuen
John W Yuen
YHYuen-Shan Ho
Yuen-Shan Ho
KCKa-Fai Chung
Ka-Fai Chung
LHLai-Ming Ho
Lai-Ming Ho
Background: Acupuncture is an alternative treatment for improving sleep, and it may attenuate oxidative stress, which is a possible pathophysiological factor in insomnia. The aim of this study was to examine the efficacy and safety of a semi-individualized acupuncture in improving sleep and explore its effect on oxidative stress parameters in adults with insomnia disorder. Methods: In this randomized sham-controlled trial, 140 participants were randomly assigned to either a 4-week semi-individualized traditional acupuncture (TA) or noninvasive sham acupuncture (SA). The primary outcome measure was the sleep-diary-derived sleep efficiency. Other outcomes included sleep diary and actigraphy, Insomnia Severity Index, anxiety and depressive symptoms, and quality of life. Blood samples were taken to measure oxidative stress parameters (malondialdehyde, glutathione peroxidase, paraoxonase, and arylesterase). Results: Although no significant difference was found in the primary outcome measure, both sleep-diary-derived and actigraphy-derived total sleep time (TST) were significantly increased in the TA group at 1-week posttreatment (mean difference in sleep diary = 22.0 min, p = 0.01, actigraphy = 18.8 min, p = 0.02). At 5-week posttreatment follow-up, a significantly higher proportion of participants in the TA group showed sleep-diary-derived sleep efficiency (SE) ≥ 85% than in the SA group (55.6% versus 36.4%, p = 0.03). Conclusion: TA and SA did not significantly differ in improving subjective sleep efficiency in individuals with insomnia disorder. However, the TA group showed a short-term effect on improving TST as measured by both sleep diary and actigraphy at 1-week posttreatment, but there were no differences in the oxidative stress parameters. Clinical Trial Registration: Registry: ClinicalTrials.gov; Title: Acupuncture in the Modulation of Peripheral Oxidative Stress Insomnia; Identifier NCT03447587; URL: https://clinicaltrials.gov/ct2/show/NCT03447587.

John W YuenJohn W Yuen
John W Yuen
WCWing Kit Chung
Wing Kit Chung
Alice Yuen LokeAlice Yuen Loke
Alice Yuen Loke
The aim in this study was to assess the effectiveness of a quaternary ammonium chloride (QAC) surfactant in reducing surface staphylococcal contamination in a routinely operating medical ward occupied by patients who had tested positive for methicillin-resistant Staphylococcus aureus (MRSA). The QAC being tested is an antibacterial film that is sprayed onto a surface and can remain active for up to 8 h. A field experimental study was designed with the QAC plus daily hypochlorite cleaning as the experimental group and hypochlorite cleaning alone as the control group. The method of swabbing on moistened surfaces was used for sampling. It was found that 83% and 77% of the bedside surfaces of MRSA-positive and MRSA-negative patients respectively were contaminated with staphylococci at 08:00 hours, and that the staphylococcal concentrations increased by 80% at 1200 h over a 4-hour period with routine ward and clinical activities. Irrespective of the MRSA status of the patients, high-touch surfaces around the bed-units within the studied medical ward were heavily contaminated (ranged 1 to 276 cfu/cm2 amongst the sites with positive culture) with staphylococcal bacteria including MRSA, despite the implementation of daily hypochlorite wiping. However, the contamination rate dropped significantly from 78% to 11% after the application of the QAC polymer. In the experimental group, the mean staphylococcal concentration of bedside surfaces was significantly (p < 0.0001) reduced from 4.4 ± 8.7 cfu/cm2 at 08:00 hours to 0.07 ± 0.26 cfu/cm2 at 12:00 hours by the QAC polymer. The results of this study support the view that, in addition to hypochlorite wiping, the tested QAC surfactant is a potential environmental decontamination strategy for preventing the transmission of clinically important pathogens in medical wards.