118 results on '"Cheung WM"'
Search Results
2. Administration of a potent antagonist of protease-activated receptor-1 (PAR-1) attenuates vascular restenosis following balloon angioplasty in rats
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P, Andrade-Gordon, C K, Derian, B E, Maryanoff, H C, Zhang, M F, Addo, Cheung Wm, B P, Damiano, M R, D'Andrea, A L, Darrow, L, de Garavilla, A J, Eckardt, E C, Giardino, B J, Haertlein, and D F, McComsey
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Male ,Indazoles ,Platelet Aggregation ,Guinea Pigs ,Cell Culture Techniques ,Graft Occlusion, Vascular ,Thrombosis ,Rats ,Rats, Sprague-Dawley ,Carotid Arteries ,Animals ,Humans ,Urea ,Receptor, PAR-1 ,Receptors, Thrombin ,Angioplasty, Balloon - Abstract
Human platelets possess two distinct thrombin-activated receptors, PAR-1 (protease-activated receptor-1) and PAR-4, whereas human vascular smooth muscle cells possess only PAR-1. Although such thrombin receptors have been studied extensively in vitro, their physiological roles are still rather ill-defined. We have now employed a potent, selective PAR-1 antagonist, RWJ-58259, to probe the in vivo significance of PAR-1 in thrombosis and vascular injury. RWJ-58259 was examined in two thrombosis models in guinea pigs: the arteriovenous (A-V) shunt assay (monitoring thrombus weight) and the Rose Bengal intravascular photoactivation assay (monitoring time to occlusion). Administration of RWJ-58259 (10 mg/kg, total i.v. dose) did not inhibit thrombus formation in either thrombosis model, although local, intrashunt delivery in the A-V shunt model did elicit a modest antithrombotic effect (thrombus weight reduction from 35 +/- 2 to 24 +/- 4 mg). These results are consistent with the presence of more than one thrombin-sensitive receptor on guinea pig platelets, in analogy with human platelets. Indeed, we were able to establish that guinea pig platelets express three thrombin receptors, PAR-1, PAR-3, and PAR-4. We also examined RWJ-58259 in a vascular restenosis model involving balloon angioplasty in rats. Perivascular administration of RWJ-58259 (10 mg) significantly reduced neointimal thickness (77 +/- 5 microm to 45 +/- 5 microm, P0.05), clearly demonstrating an important role for PAR-1 in vascular injury. From these results, it is evident that a PAR-1 antagonist is not especially effective for treating platelet-dependent thrombosis; however, it could well be beneficial for treating restenosis attendant to arterial injury.
- Published
- 2001
3. Iridium and rhodium complexes containing dichalcogenoimidodiphosphinato ligands
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Cheung, WM, Lai, CY, Zhang, QF, Wong, WY, Williams, ID, Leung, WH, Cheung, WM, Lai, CY, Zhang, QF, Wong, WY, Williams, ID, and Leung, WH
- Abstract
Treatment of [MCl(CO)(PPh3)(2)] with K[N(R(2)PQ)(2)] afforded [M{N(Ph(2)PQ)(2)}(CO)(PPh3)] (M = Ir, Rh; Q = S, Se). The IR C=O stretching frequencies for [M(CO)(PPh3){N(Ph(2)PQ)(2)]} were found to decrease in the order S > Se. Treatment of [M(COD)Cl](2) with K[N(Ph(2)PQ)(2)] afforded [M(COD){N(Ph(2)PQ)(2)}] (COD = 1,5-cyclooctadiene; M = Ir, Rh; Q = S, Se). Treatment of [Ir(ol)(2)Cl] with K[N(Pr(2)(i)pQ)(2)] afforded [Ir(ol)(2){N(Pr(2)(i)PQ)(2)}](2) (ol = cyclooctene COE, C2H4; Q = S, Se). Oxidative addition of [Ir(CO)(PPh3)K[N((Ph2S)-S-i)(2)\}] and [Ir(COD){N(Ph2PS)(2)}] with HCl afforded [Ir(H)(Cl)(CO)(PPh3){N(Ph2PS)(2)}] and trans-[Ir(H)(Cl)(COD){N(Ph2PS)(2)}], respectively. Oxidative addition of [Ir(CO)(PPh3){N(Ph2PS)(2)}] with MeI afforded [Ir(Me)(I)(CO)(PPh3)(N(Ph2PS)(2)\}]. Treatment of [Ir(COE)(2)Cl](2) with K[N(R2PO)(2)] afforded [Ir(COE)(2){N(Ph2PO)(2)}] that reacted with MeOTf (OTf = triffate) to give [Ir{N(Ph2PO)(2)}(COE)(2)(Me)(OTf)]. The crystal structures of [Ir(CO)(PPh3){N(Ph2PS)(2)}], [M(COD){N(Ph2PS)(2)}] (M = Ir, Rh), [Ir(ol)(2){N((Pr2PS)-P-i)(2)}](ol = COE, C2H4), trans-[Ir(H)(Cl)(COD){N(Ph2PS)(2)}], and [Ir(COE)(2){N(Ph2PO)(2)}] have been determined. (c) 2005 Elsevier B.V. All rights reserved.
- Published
- 2006
4. Design change impact analysis during early design specification
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Mckay, Kr, primary, Bramall, Dg, additional, Rogers, Bc, additional, Chapman, P, additional, Cheung, Wm, additional, and Maropoulos, Pg, additional
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- 2003
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5. Application of product data management technologies for enterprise integration
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Gao, Jx, primary, Aziz, Hayder, additional, Maropoulos, Pg, additional, and Cheung, Wm, additional
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- 2003
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6. Manufacturability analysis of early product designs
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Bramall, Dg, primary, Mckay, Kr, additional, Rogers, Bc, additional, Chapman, P, additional, Cheung, Wm, additional, and Maropoulos, Pg, additional
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- 2003
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7. Ligand-activated peroxisome proliferator-activated receptor-gamma protects against ischemic cerebral infarction and neuronal apoptosis by 14-3-3 epsilon upregulation.
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Wu JS, Cheung WM, Tsai YS, Chen YT, Fong WH, Tsai HD, Chen YC, Liou JY, Shyue SK, Chen JJ, Chen YE, Maeda N, Wu KK, Lin TN, Wu, Jui-Sheng, Cheung, Wai-Mui, Tsai, Yau-Sheng, Chen, Yi-Tong, Fong, Wen-Hsuan, and Tsai, Hsin-Da
- Published
- 2009
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8. Effects of mindful and non-mindful exercises on people with depression: a systematic review.
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Tsang HW, Chan EP, and Cheung WM
- Abstract
PURPOSE: An emerging body of evidence has shown the therapeutic effect of both mindful and non-mindful physical exercises on the treatment of depression. The purpose of this study is to examine the effectiveness of mindful and non-mindful physical exercises as an intervention in managing depression or depressive symptoms based on a systematic literature review. METHODS: Our review was conducted among five electronic databases to identify randomized controlled trials (RCTs), which tested the effects of mindful or/and non-mindful physical exercises on depression. Studies were classified according to the baseline depression status of participants and its relation to allocation concealment, blinding at outcome assessment, follow-up, and whether intention to treat analysis was employed. RESULTS: The results based on 12 RCTs indicated that both the mindful and non-mindful physical exercises were effective in their short-term effect in reducing depression levels or depressive symptoms. However, most of studies had methodological problems that only small sample size was used, and the maintenance effects of physical exercise were not reported. Specific comparisons between RCTs on mindful and non-mindful exercises were not performed because of the limitations on the designs. CONCLUSIONS: We recommend that more well-controlled studies have to be conducted in the future to address the short- and long-term effects of physical exercise on alleviating depression. Efforts should be focused on unveiling the differential effects of mindful and non-mindful exercises on depression and the underlying mechanisms of their therapeutic action. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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9. Clinical evaluation of ceftibuten in gonorrhea. A pilot study in Hong Kong.
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Chong LY, Cheung WM, Leung CS, Yu CW, Chan LY, Chong, L Y, Cheung, W M, Leung, C S, Yu, C W, and Chan, L Y
- Abstract
Background: The escalating rates of gonococcal resistance to quinolone in Hong Kong have prompted a search for an alternative first-line antimicrobial agent for use in treating uncomplicated gonococcal urethritis. Ceftibuten is an orally active third-generation cephalosporin with potent in vitro activity against Neisseria gonorrhoeae. Its pharmacokinetic properties allow single-dose administration.Objective: To evaluate the efficacy, safety, and tolerability of ceftibuten in the treatment of uncomplicated gonorrhea in men.Study Design: Ceftibuten was evaluated in an open-label, noncomparative, multicenter study. Eligible men with uncomplicated gonococcal urethritis were treated with a single 400-mg oral dose of ceftibuten and reassessed 1 week and 3 weeks after treatment. The main outcome measures were the isolation of N. gonorrhoeae, patient-reported side effects, and other safety parameters (e.g., blood counts and renal and hepatic function tests).Results: One hundred twenty-five men were enrolled in the study. The overall cure rate was 98.2% (110 of 112 evaluable patients). Adverse events, which occurred in 4.5% of patients, were all mild, well tolerated, and of short duration. No significant changes in laboratory test results were noted. Of the 125 isolates, 4.8% were -lactamase positive. Susceptibility to ofloxacin was found to be low in 59.2% of isolates (MIC 0.1 to < 1g/mL) and 25.6% of isolates were resistant (MIC1g/mL) to ofloxacin.Conclusions: A single 400-mg oral dose of ceftibuten is highly effective and well tolerated in the treatment of uncomplicated gonococcal urethritis in men. [ABSTRACT FROM AUTHOR]- Published
- 1998
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10. Influence of the extent of the zone at risk on the effectiveness of drugs in reducing infarct size
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L G Ribeiro, Cheung Wm, and P R Maroko
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medicine.medical_specialty ,Gallopamil ,Myocardial Infarction ,Collateral Circulation ,Coronary circulation ,Dogs ,Physiology (medical) ,Internal medicine ,Coronary Circulation ,medicine ,Animals ,Myocardial infarction ,business.industry ,Myocardium ,medicine.disease ,Collateral circulation ,Infarct size ,Calcium Channel Blockers ,Disease Models, Animal ,medicine.anatomical_structure ,Verapamil ,Anesthesia ,Cardiology ,Autoradiography ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Published
- 1982
11. Effects of yoga on stress management in healthy adults: A systematic review.
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Chong CS, Tsunaka M, Tsang HW, Chan EP, and Cheung WM
- Abstract
OBJECTIVE: This article reports a systematic review and critical appraisal of the effect of yoga on stress management in healthy adults. METHODS: A systematic literature search was performed to identify randomized controlled trials (RCTs) and clinical controlled trials (CCTs) that assessed the effects of yoga on stress management in healthy adults. Selected studies were classified according to the types of intervention, duration, outcome measures, and results. They were also qualitatively assessed based on Public Health Research, Education and Development standards. RESULTS: The systematic review was based on eight RCTs and CCTs that indicated a positive effect of yoga in reducing stress levels or stress symptoms. However, most of the studies had methodological problems in that the intervention duration was short and limited follow-up data was available. CONCLUSION: This review revealed positive effects of yoga on stress reduction in healthy adult populations. However, the result should be interpreted with caution due to the small number of studies and the associated methodological problems. Further studies to ascertain yoga's long-term effects and the underlying biological mechanisms leading to its stress reduction effect should be conducted. [ABSTRACT FROM AUTHOR]
- Published
- 2011
12. Ecodesign of Kesterite Nanoparticles for Thin Film Photovoltaics at Laboratory Scale.
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Jones MDK, Willis BL, Campbell S, Kartopu G, Maiello P, Punathil P, Cheung WM, Woolley E, Jones LCR, Oklobia O, Holland A, Barrioz V, Zoppi G, Beattie NS, and Qu Y
- Abstract
This manuscript investigates the efficient synthesis of copper zinc tin sulfide (CZTS) nanoparticles for CZTS thin film solar cell applications with a primary focus on environmental sustainability. Underpinning the investigation is an initial life-cycle assessment (LCA) analysis. This LCA analysis is conducted to evaluate the environmental impact of different synthesis volumes, providing crucial insights into the sustainability of the synthesis process by considering the flows of material and energy associated with the process. Life-cycle assessment results demonstrate that significant reductions to the environmental impact can be made by increasing the synthesis volume of CZTS nanoparticle ink. Using a 5-fold increase in volume can reduce all 11 investigated environmental impacts by up to 35.6%, six of these impacts demonstrating reductions >10% and the amount of global warming potential is reduced by 21.4%. Motivated by the LCA results, COMSOL simulations are employed to understand the fluid flow patterns in large-scale fabrication. Various sizes and speeds of stirrer bars are investigated in these simulations, and it is determined that a 50 mm stir bar at 200 rpm represents the optimal configuration for the synthesis process in a 500 mL flask. Subsequently, large-batch CZTS nanoparticle inks are synthesized using these parameters and compared to small-batch samples. The light absorbers are characterized using Raman spectroscopy and X-ray diffraction, confirming favorable properties with close-to-ideal elemental ratios in large-batch synthesis. Finally, solar cell devices fabricated utilizing CZTSSe absorbers from the large volume synthesis process demonstrate comparable performance to those fabricated using small-batch synthesis, with uniform power conversion efficiencies of around 5% across the substrate. This study highlights the potential of large-volume CZTS nanoparticle synthesis for efficient and environmentally friendly CZTS solar cell fabrication, contributing to the advancement of sustainable renewable energy technologies., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)
- Published
- 2024
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13. Cointegrations in house price dynamics and ageing population risks.
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Cheung WM
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- Humans, Population Dynamics, Housing, Aging, Urban Population, Emigration and Immigration, Rural Population
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How does the riskiness of an ageing population change with house price dynamics of rural areas? Why do rural house prices increase faster than cities despite their ageing populations? Life cycle theory predicts working age households have higher demand for housing than retirement households. An issue that has seen much less attention in the literature is that rural house prices have been increasing despite their populations age rapidly. To answer these issues, our paper introduces an empirical cointegration-based framework designed to be flexible for empirical settings. Our cointegration framework reveals crucial information about rural housing and ageing which has not been found previously: the short-term deviation of house prices from cointegration restrictions is a strong predictor of future rural house prices and migration rate from 1 to 4 year ahead. This is not the case for urban areas nor where cointegration restrictions are being ignored. Rural house prices, not urban ones, are the key to understand this cointegration restriction. Our framework is pertinent to most ageing societies with available housing and demographic data. When a government formulates macroprudential policies internalizing these cointegration restrictions and supporting rural developments, migration into rural areas and population increases are possible. Our evidence highlights the importance of cointegration-based long-run ageing risks for rural housing markets., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 William M. Cheung. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2024
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14. Enhancing Subjective Well-Being Through Qigong: A Randomized Controlled Trial in Older Adults in Hong Kong With Chronic Physical Illness.
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Cai S, Tsang HWH, Lu EY, Leung MKW, Hong Siu DC, Yun Leung S, Lap Yan Au F, Cheung WM, and Jensen MP
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- Male, Female, Humans, Aged, Hong Kong, Quality of Life, Hand Strength, Chronic Disease, Qigong methods
- Abstract
Context: Eight-section Brocades, a qigong protocol, has been shown to reduce depressive symptoms in older adults with chronic physical illness, but its positive effects on quality of life, such as subjective well-being, aren't known., Objective: This study intended to evaluate the efficacy of qigong for increasing subjective well-being in older adults with chronic physical illness., Design: A randomized controlled trial was conducted., Setting: A governmental family clinic in Hong Kong., Participants: Participants were 47 older adults, 19 males and 28 females, with chronic physical illness., Intervention: Participants were randomly assigned to an Eight-section Brocades group (n = 25) or a cognitive training group (n = 22). The groups received 12 weeks of the Eight-section Brocades intervention or of cognitive training, respectively., Outcome Measures: The primary outcome-subjective well-being-and the secondary outcomes-functional independence, sleep quality, mobility, and hand grip strength-were assessed at baseline, postintervention, and at a one-month follow-up., Results: No significant between-group differences were observed in improvements in subjective well-being or any of the secondary outcomes. Significant improvements in subjective sleep quality and decreases in daytime dysfunction over time were reported by participants in both groups., Conclusions: The findings didn't support 12 weeks of Eight-section Brocades qigong as an effective treatment to enhance the subjective well-being of older adults with chronic physical illness. These null findings may be due to the possibilities that: (1) the treatment may have minimal effects on positive psychology outcomes; (2) the primary outcome measure showed possible ceiling effects for the groups; (3) the current study used an active control condition that may have had more benefits than the control conditions used in previous studies; (4) the current study may have been underpowered; (5) more than 12 weeks (24 sessions) of qigong may be required to impact well-being; or (6) some combination of these factors may have affected the results.
- Published
- 2023
15. The early language gap between first- and second-language learners: acquisition of Chinese characters among preschoolers.
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Chan SWY, Cheung WM, and Marton F
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For culturally and linguistically diverse children, early second language (L2) development is important for school achievement and social inclusion. These children face challenges in acquiring L2, especially in Hong Kong, where the dominant Chinese language contrasts strongly with their home languages. Studies that compared the language abilities of first language (L1) and L2 students in English-speaking contexts have reported young L2 learners' disadvantage in using the dominant language in oral language and comprehension at school entry. The findings raise the question of whether L2 learners who fall behind their L1 peers in language abilities will be further disadvantaged, showing a weaker development gradient. This study used the Chinese Character Acquisition Assessment (CCAA) to compare character acquisition of 491 L2 children aged from 3 to 6 years against that of 240 of their L1 peers from Hong Kong kindergartens. The CCAA is comprised of six subtests and assesses children's abilities to make associations among character written form (orthography), sound, and meaning. Results showed that L2 learners had greater development in meaning and sound associations across class levels, implying that they may first develop oral language related abilities. In addition, results indicate that diverging gaps between L1 and L2 learners' Chinese character acquisition existed across class levels for the associations involving written character form, but not in regard to associations between character meaning and sound. This study highlights the Chinese learning needs of L2 preschoolers and provides understanding of their abilities in mapping among character written forms, sounds, and meanings. The findings suggest the importance of supporting L2 children's oral language at earlier stages of Chinese learning, and the need to provide instructional support to compensate for their relative weakness in literacy at school entry., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Chan, Cheung and Marton.)
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- 2023
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16. Protective Effect of Ergothioneine Against Stroke in Rodent Models.
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Ong WY, Kao MH, Cheung WM, Leow DM, Cheah IK, and Lin TN
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- Rats, Mice, Animals, Rodentia, Infarction, Middle Cerebral Artery complications, Disease Models, Animal, Ergothioneine pharmacology, Ergothioneine therapeutic use, Stroke drug therapy, Stroke complications, Brain Ischemia drug therapy, Brain Ischemia complications
- Abstract
Ergothioneine (ET) is a naturally occurring antioxidant and cytoprotective agent that is synthesized by fungi and certain bacteria. Recent studies have shown a beneficial effect of ET on neurological functions, including cognition and animal models of depression. The aim of this study is to elucidate a possible effect of ET in rodent models of stroke. Post-ischemic intracerebroventricular (i.c.v.) infusion of ET significantly reduced brain infarct volume by as early as 1 day after infusion in rats, as shown by triphenyltetrazolium chloride (TTC) assay. There was a dose-dependent increase in protection, from 50 to 200 ng of ET infusion. These results suggest that ET could have a protective effect on CNS neurons. We next elucidated the effect of systemic ET on brain infarct volume in mice after stroke. Daily i.p. injection of 35 mg/kg ET (the first dose being administered 3 h after stroke) had no significant effect on infarct volume. However, daily i.p. injections of 70 mg/kg, 100 mg/kg, 125 mg/kg and 150 mg/kg ET, with the first dose administered 3 h after stroke, significantly decreased infarct volume at 7 days after vessel occlusion in mice. In order to elucidate at what time interval during the 7 days there could be effective protection, a second set of experiments was carried out in mice, using one of the effective loading protocols, i.e. 125 mg/kg i.p. ET but the brains were analyzed at 1, 4 and 7 days post-stroke by MRI. We found that ET was already protective against neuronal injury and decreased the size of the brain infarct from as early as 1 day post-stroke. Behavioral experiments carried out on a third set of mice (using 125 mg/kg i.p. ET) showed that this was accompanied by significant improvements in certain behaviors (pole test) at 1 day after stroke. Together, results of this study indicate that i.c.v. and systemic ET are effective in reducing brain infarct volume after stroke in rodent models., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
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- 2023
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17. The relationship between liver function and neurophysiological factors in depressed individuals: a cross-sectional study using an integrated "East meets West" medicine approach.
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Ye J, Yu Y, Chung RCK, Lian X, Wang X, Cheung WM, and Tsang HWH
- Abstract
Introduction: Depression is a common mental disorder worldwide. The pathology of depression may involve the dysregulation of neurotransmitters and immunity and produce genetic and environmental effects. Traditional Chinese Medicine (TCM) has been practiced for several thousand years and has a different understanding of depression compared to Western medicine. However, this approach has not been widely accepted by scientific communities as TCM mainly focuses on clinical practice., Methods: In this study, we conducted a cross-sectional study among 100 participants in a rehabilitation hospital to analyze the plausible pathways linking TCM-based liver function and depression, which we hypothesized in a prior theoretical review., Results: A significant relationship between adrenocorticotropic hormone and TCM-based liver function was found ( r = 0.211, p = 0.041). Cortisol was significantly associated with norepinephrine ( r = 0.243, p = 0.015) and adrenocorticotropic hormone ( r = 0.302, p < 0.001). A positive significant relationship was also found between norepinephrine and adrenocorticotropic hormone ( r = 0.272, p < 0.001). There was no significant relationship between the ratio from low frequency to high frequency and TCM-based liver function ( p = 0.690)., Discussion: These results suggest that TCM-based liver function can be interpreted using the hypothalamic-pituitary-adrenal axis. This is a pioneering study to examine the mechanisms of depression in relation to liver function by integrating Eastern and Western medical approaches. The findings of this study are valuable for a deeper understanding of depression and public education., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Ye, Yu, Chung, Lian, Wang, Cheung and Tsang.)
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- 2023
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18. Activating Transcription Factor 3 Diminishes Ischemic Cerebral Infarct and Behavioral Deficit by Downregulating Carboxyl-Terminal Modulator Protein.
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Kao MH, Huang CY, Cheung WM, Yan YT, Chen JJ, Ho YS, Hsu CY, and Lin TN
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- Mice, Animals, Activating Transcription Factor 3 genetics, Activating Transcription Factor 3 metabolism, Carrier Proteins metabolism, Mice, Knockout, Brain Infarction genetics, RNA, Small Interfering genetics, Cerebral Infarction, Palmitoyl-CoA Hydrolase metabolism, Proto-Oncogene Proteins c-akt metabolism, Brain Ischemia genetics, Brain Ischemia metabolism
- Abstract
Activating transcription factor 3 (ATF3) is a stress-induced transcription factor and a familiar neuronal marker for nerve injury. This factor has been shown to protect neurons from hypoxic insult in vitro by suppressing carboxyl-terminal modulator protein (CTMP) transcription, and indirectly activating the anti-apoptotic Akt/PKB cascade. Despite prior studies in vitro, whether this neuroprotective pathway also exists in the brain in vivo after ischemic insult remains to be determined. In the present study, we showed a rapid and marked induction of ATF3 mRNA throughout ischemia-reperfusion in a middle cerebral artery (MCA) occlusion model. Although the level of CTMP mRNA was quickly induced upon ischemia, its level showed only a mild increase after reperfusion. With the gain-of-function approach, both pre- and post-ischemic administration of Ad-ATF3 ameliorated brain infarct and neurological deficits. Whereas, with the loss-of-function approach, ATF3 knockout (KO) mice showed bigger infarct and worse functional outcome after ischemia. In addition, these congenital defects were rescued upon reintroducing ATF3 to the brain of KO mice. ATF3 overexpression led to a lower level of CTMP and a higher level of p-Akt(473) in the ischemic brain. On the contrary, ATF3 KO resulted in upregulation of CTMP and downregulation of p-Akt(473) instead. Furthermore, post-ischemic CTMP siRNA knockdown led to smaller infarct and better behaviors. CTMP siRNA knockdown increased the level of p-Akt(473), but did not alter the ATF3 level in the ischemic brain, upholding the ATF3→CTMP signal cascade. In summary, our proof-of-principle experiments support the existence of neuroprotective ATF3→CTMP signal cascade regulating the ischemic brain. Furthermore, these results suggest the therapeutic potential for both ATF3 overexpression and CTMP knockdown for stroke treatment.
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- 2023
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19. Double Disadvantage of Carers with a Disability: A Cross-Sectional Study of Care Duration and Perceived Importance for Service Improvement in Hong Kong, China.
- Author
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Chan W, Xin M, Lu EY, Cheung WM, and Tsang HWH
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- Humans, Cross-Sectional Studies, Hong Kong, China, Caregivers, Disabled Persons
- Abstract
Objectives: this study examined (i) the relationships between the care duration of carers and their perceptions of the importance of service improvement by types of service, and (ii) whether carers had a disability that moderated the impacts of care duration on these perceptions., Design: survey data for cross-sectional analyses., Method: The sample consisted of carers without disability ( n = 625) and carers with a disability ( n = 77). Hierarchical multiple regression was applied to examine the unique contribution of care duration. The interaction effects of the disability status of the carer was also estimated., Results: Longer care duration was associated with a greater perception of the importance of service improvement for certain services by carers. The positive relationships between care duration and perception of the importance of caregiver assistances and financial subsidy improvement were stronger for carers with disabilities compared to carers without disability., Conclusions: Long-term carers with disabilities face a potential double disadvantage of service improvement needs with more years of caregiving. Policy makers should consider prioritizing caregiver assistances or financial subsidy service improvements for long-term carers who themselves have a disability.
- Published
- 2022
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20. A scenario-based approach to predict energy demand and carbon emission of electric vehicles on the electric grid.
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Cheung WM
- Subjects
- Gasoline analysis, Electricity, Fossil Fuels, Motor Vehicles, Vehicle Emissions analysis, Carbon Dioxide analysis
- Abstract
UK plans to ban the sale of new diesel and petrol cars by 2030 to be replaced by electric vehicles (EVs). The question is, will the UK's electrical grid infrastructure ready for this change? This comparative study investigates the effect of UK green vehicles on the electrical grid and presents a new insight into improving their energy demand and carbon dioxide (CO
2 ) emissions to the electrical grid. The results show that even when there is a very high level of market penetration of EVs, the overall effect on annual energy consumption may seem minimal. On the contrary, the effect that EVs may have on the electrical grid is dependent on the time-of-day EVs are being charged. Therefore, this study concludes that measures need to be put in place to control charging times of EVs and this would help restrict the total daily electricity and electrical energy demands. The introduction of EVs reduces the overall CO2 emissions mainly because a proportion of petrol and diesel cars are replaced by EVs. However, CO2 emissions can only reduce up to a certain level and this reduction of CO2 will have less effect due to an increasing number of EVs in the electrical grid. To reduce CO2 emissions further, the electricity that relies on high-carbon fossil fuels in the electrical grid should be set at the minimum level., (© 2022. The Author(s).)- Published
- 2022
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21. Types of Community Support Services and Self-Efficacy for Continuous Community Living among Individuals with Disabilities and Caregivers.
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Chan W, Cao Y, Lu EY, Cheung WM, and Tsang HWH
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- Community Support, Cross-Sectional Studies, Humans, Self Efficacy, Caregivers, Disabled Persons
- Abstract
This study explored the impacts of five types of community support services (i.e., center-based care, home-based care, respite care, caregiver assistance, and financial subsidies) on self-efficacy for continuous community living among individuals with disabilities and caregivers., Design: Cross-sectional., Method: The sample consisted of a group of individuals with disabilities ( n = 948) and a group of caregivers ( n = 522). A mixed ANOVA was applied to explore the differences in the perceived importance of improvements to community support services between the groups. Logistic regression analyses were conducted to examine the perceived importance of improvements to types of community support services for self-efficacy for continuous community living., Results: Caregivers perceived higher levels of importance for improvements to community support services than individuals with disabilities. Both groups reported that financial subsidies were the most important area for improvement. The greater importance of improvements to financial subsidies reported by caregivers predicted greater odds for self-efficacy for continuous community living. The greater importance of improvements to center-based services reported by individuals with disabilities predicted greater odds for self-efficacy for continuous community living., Conclusions: The findings suggested that financial subsidies for caregivers and center-based services for individuals with disabilities could improve self-efficacy for continuous community living.
- Published
- 2022
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22. Synthesis, structure and reactivity of iridium complexes containing a bis-cyclometalated tridentate C^N^C ligand.
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Cheung WM, Chong MC, Sung HH, Cheng SC, Williams ID, Ko CC, and Leung WH
- Abstract
In an effort to synthesize cyclometalated iridium complexes containing a tridentate C^N^C ligand, transmetallation of [Hg(HC^N^C)Cl] (1) (H2C^N^C = 2,6-bis(4-tert-butylphenyl)pyridine) with various organoiridium starting materials has been studied. The treatment of 1 with [Ir(cod)Cl]2 (cod = 1,5-cyclooctadiene) in acetonitrile at room temperature afforded a hexanuclear Ir4Hg2 complex, [Cl(κ2C,N-HC^N^C)(cod)IrHgIr(cod)Cl2]2 (2), which features Ir-Hg-Ir and Ir-Cl-Ir bridges. Refluxing 2 with sodium acetate in tetrahydrofuran (thf) resulted in cyclometalation of the bidentate HC^N^C ligand and formation of trinuclear [(C^N^C)(cod)IrHgIr(cod)Cl2] (3). On the other hand, refluxing [Ir(cod)Cl]2 with 1 and sodium acetate in thf yielded [Ir(C^N^C)(cod)(HgCl)] (4). Chlorination of 4 with PhICl2 gave [Ir(C^N^C)(cod)Cl]·HgCl2 (5·HgCl2) that reacted with tricyclohexylphosphine to yield Hg-free [Ir(C^N^C)(cod)Cl] (5). Chloride abstraction of 5 with silver(i) triflate (AgOTf) gave [Ir(C^N^C)(cod)(H2O)](OTf) (6) that can catalyze the cyclopropanation of styrene with ethyl diazoacetate. Reaction of 1 and [Ir(CO)2Cl(py)] (py = pyridine) with sodium acetate in refluxing thf afforded [Ir(C^N^C)(HgCl)(py)(CO)] (7), in which the carbonyl ligand is coplanar with the C^N^C ligand. On the other hand, refluxing 1 with (PPh4)[Ir(CO)2Cl2] and sodium acetate in acetonitrile gave [Ir(C^N^C)(κ2C,N-HC^N^C)(CO)] (8), the carbonyl ligand of which is trans to the pyridyl ring of the bidentate HC^N^C ligand. Upon irradiation with UV light 8 in thf was isomerized to 8', in which the carbonyl is trans to a phenyl group of the bidentate HC^N^C ligand. The isomer pair 8 and 8' exhibited emission at 548 and 514 nm in EtOH/MeOH at 77 K with lifetime of 84.0 and 64.6 μs, respectively. Protonation of 8 with p-toluenesulfonic acid (TsOH) afforded the bis(bidentate) tosylate complex [Ir(κ2C,N-HC^N^C)2(CO)(OTs)] (9) that could be reconverted to 8 upon treatment with sodium acetate. The electrochemistry of the Ir(C^N^C) complexes has been studied using cyclic voltammetry. Reaction of [Ir(PPh3)3Cl] with 1 and sodium acetate in refluxing thf led to isolation of the previously reported compound [Ir(κ2P,C-C6H4PPh2)2(PPh3)Cl] (10). The crystal structures of 2-5, 8, 8', 9 and 10 have been determined.
- Published
- 2021
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23. Crack Detection and Localisation in Steel-Fibre-Reinforced Self-Compacting Concrete Using Triaxial Accelerometers.
- Author
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Ramli J, Coulson J, Martin J, Nagaratnam B, Poologanathan K, and Cheung WM
- Abstract
Cracking in concrete structures can significantly affect their structural integrity and eventually lead to catastrophic failure if undetected. Recent advances in sensor technology for structural health monitoring techniques have led to the development of new and improved sensors for real-time detection and monitoring of cracks in various applications, from laboratory tests to large structures. In this study, triaxial accelerometers have been employed to detect and locate micro- and macrocrack formation in plain self-compacting concrete (SCC) and steel-fibre-reinforced SCC (SFRSCC) beams under three-point bending. Experiments were carried out with triaxial accelerometers mounted on the surface of the beams. The experimental results revealed that triaxial accelerometers could be used to identify the locations of cracks and provide a greater quantity of useful data for more accurate measurement and interpretation. The study sheds light on the structural monitoring capability of triaxial acceleration measurements for SFRSCC structural elements that can act as an early warning system for structural failure.
- Published
- 2021
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24. Clinacanthus nutans Mitigates Neuronal Death and Reduces Ischemic Brain Injury: Role of NF-κB-driven IL-1β Transcription.
- Author
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Kao MH, Wu JS, Cheung WM, Chen JJ, Sun GY, Ong WY, Herr DR, and Lin TN
- Subjects
- Animals, Anti-Inflammatory Agents pharmacology, Cell Death drug effects, Cells, Cultured, Cerebral Infarction pathology, Drug Evaluation, Preclinical, Glucose pharmacology, Interleukin-1beta genetics, Male, NF-KappaB Inhibitor alpha metabolism, Oxygen pharmacology, Phytotherapy, Promoter Regions, Genetic, Protein Transport drug effects, RNA Interference, RNA, Small Interfering genetics, Rats, Rats, Long-Evans, Transcription Factor RelA antagonists & inhibitors, Transcription Factor RelA genetics, Transcription, Genetic drug effects, Tumor Necrosis Factor-alpha biosynthesis, Tumor Necrosis Factor-alpha genetics, Acanthaceae chemistry, Anti-Inflammatory Agents therapeutic use, Brain Ischemia drug therapy, Infarction, Middle Cerebral Artery drug therapy, Interleukin-1beta biosynthesis, NF-kappa B metabolism, Neurons drug effects, Plant Extracts pharmacology, Plant Leaves chemistry, Plants, Medicinal chemistry
- Abstract
Neuroinflammation has been shown to exacerbate ischemic brain injury, and is considered as a prime target for the development of stroke therapies. Clinacanthus nutans Lindau (C. nutans) is widely used in traditional medicine for treating insect bites, viral infection and cancer, due largely to its anti-oxidative and anti-inflammatory properties. Recently, we reported that an ethanol extract from the leaf of C. nutans could protect the brain against ischemia-triggered neuronal death and infarction. In order to further understand the molecular mechanism(s) for its beneficial effects, two experimental paradigms, namely, in vitro primary cortical neurons subjected to oxygen-glucose deprivation (OGD) and in vivo rat middle cerebral artery (MCA) occlusion, were used to dissect the anti-inflammatory effects of C. nutans extract. Using promoter assays, immunofluorescence staining, and loss-of-function (siRNA) approaches, we demonstrated that transient OGD led to marked induction of IL-1β, IL-6 and TNFα, while pretreatment with C. nutans suppressed production of inflammatory cytokines in primary neurons. C. nutans inhibited IL-1β transcription via preventing NF-κB/p65 nuclear translocation, and siRNA knockdown of either p65 or IL-1β mitigated OGD-mediated neuronal death. Correspondingly, post-ischemic treatment of C. nutans attenuated IκBα degradation and decreased IL-1β, IL-6 and TNFα production in the ischemic brain. Furthermore, IL-1β siRNA post-ischemic treatment reduced cerebral infarct, thus mimicking the beneficial effects of C. nutans. In summary, our findings demonstrated the ability for C. nutans to suppress NF-κB nuclear translocation and inhibit IL-1β transcription in ischemic models. Results further suggest the possibility for using C. nutans to prevent and treat stroke patients.
- Published
- 2021
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25. Oxidizing Cerium(IV) Alkoxide Complexes Supported by the Kläui Ligand [Co(η 5 -C 5 H 5 ){P(O)(OEt) 2 } 3 ] - : Synthesis, Structure, and Redox Reactivity.
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Wong KH, Cheung WM, Pham HL, So YM, Sung HH, Williams ID, and Leung WH
- Abstract
Tetravalent cerium alkoxide complexes supported by the Kläui tripodal ligand [Co(η
5 -C5 H5 ){P(O)(OEt)2 }3 ]- (LOEt - ) have been synthesized, and their nucleophilic and redox reactivity have been studied. Treatment of the Ce(IV) oxo complex [CeIV (LOEt )2 (O)(H2 O)]·MeCONH2 ( 1 ) withi PrOH or reaction of [CeIV (LOEt )2 Cl2 ] ( 2 ) with Ag2 O ini PrOH afforded the Ce(IV) dialkoxide complex [CeIV (LOEt )2 (Oi Pr)2 ] ( 3- i Pr ). The methoxide and ethoxide analogues [CeIV (LOEt )2 (OR)2 ] (R = Me ( 3-Me ), Et ( 3-Et )) have been prepared similarly from 2 and Ag2 O in ROH. Reaction of 3- i Pr with an equimolar amount of 2 yielded a new Ce(IV) complex that was formulated as the chloro-alkoxide complex [CeIV (LOEt )2 (Oi Pr)Cl] ( 4 ). Treatment of 3- i Pr with HX and methyl triflate (MeOTf) afforded [Ce(LOEt )2 X2 ] (X- = Cl- , NO3 - , PhO- ) and [CeIV (LOEt )2 (OTf)2 ], respectively, whereas treatment with excess CO2 in hexane led to isolation of the Ce(IV) carbonate [CeIV (LOEt )2 (CO3 )]. 3- i Pr reacted with water in hexane to give a Ce(III) complex and a Ce(IV) species, presumably the reported tetranuclear oxo cluster [CeIV 4 (LOEt )4 (O)5 (OH)2 ]. The Ce(IV) alkoxide complexes are capable of oxidizing substituted phenols, possibly via a proton-coupled electron transfer pathway. Treatment of 3- i Pr with ArOH afforded the Ce(III) aryloxide complexes [CeIII (LOEt )2 (OAr)] (Ar = 2,4,6-tri- tert -butylphenyl ( 5 ), 2,6-diphenylphenyl ( 6 )). On the other hand, a Ce(III) complex containing a monodeprotonated 2,2'-biphenol ligand, [CeIII (LOEt )2 (t Bu4 C12 H4 O2 H)] ( 7 ) (t Bu4 C12 H4 O2 H2 = 4,4',6,6'-tetra- tert -butyl-2,2'-biphenol), was isolated from the reaction of 3- i Pr with 2,4-di- tert -butylphenol. The crystal structures of complexes 3- i Pr , 3-Me , 3-Et , and 5 - 7 have been determined.- Published
- 2021
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26. Comparing Mindful and Non-Mindful Exercises on Alleviating Anxiety Symptoms: A Systematic Review and Meta-Analysis.
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So WWY, Lu EY, Cheung WM, and Tsang HWH
- Subjects
- Exercise, Exercise Therapy, Humans, Anxiety therapy, Mindfulness, Yoga
- Abstract
Background: In recent years, studies and reviews have reported the therapeutic benefits of both mindful and non-mindful exercises in reducing anxiety. However, there have not been any systematic reviews to compare their relative effectiveness for therapeutic application, especially among the non-clinical population. Thus, the aim of this review is to compare the effectiveness between mindful and non-mindful exercise on treating anxiety among non-clinical samples., Methods: Potential articles were retrieved from PubMed, Embase, Academic Search Premier, and PsycInfo. Randomized controlled trials, which involved both mindful and non-mindful exercises as intervention, and the use of anxiety outcome measures were included., Results: Twenty-four studies fulfilled the inclusion criteria and were included in our systematic review. In addition, 14 studies provided sufficient data to be included in the meta-analysis. For studies that reported significant group differences at post-assessment, results showed that mindful exercise was more beneficial in reducing anxiety than non-mindful exercise. The meta-analysis reported that yoga was more effective in reducing anxiety than non-mindful exercise., Conclusions: Compared to non-mindful exercise, yoga is shown to be more effective in alleviating anxiety symptoms. It is recommended that yoga could be used as a primary healthcare intervention to help the public reduce anxiety.
- Published
- 2020
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27. Qigong for the treatment of depressive symptoms: Preliminary evidence of neurobiological mechanisms.
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Lu EY, Lee P, Cai S, So WWY, Ng BFL, Jensen MP, Cheung WM, and Tsang HWH
- Subjects
- Aged, Chronic Disease, Depression therapy, Humans, Hydrocortisone, Reproducibility of Results, Qigong
- Abstract
Objectives: Qigong has been shown to effectively reduce depressive symptoms in older adults with chronic physical illness. Here, we sought to evaluate the effects of qigong on serotonin, cortisol, and Brain-derived Neurotropic Factors (BDNF) levels and test their roles as potential mediators of the effects of qigong on depressive symptoms., Methods: Thirty older adults with chronic physical illness participated in a randomized clinical trial. They were randomly assigned to a qigong group (n = 14) or a control group for cognitive training of executive function and memory (n = 16). The participants provided blood and saliva samples at baseline and post-intervention. Levels of cortisol were measured from the salvia samples, and serotonin and BDNF were measured from the blood samples., Results: Consistent with the study findings presented in the primary outcome paper, a significant Group × Time interaction effect emerged on depressive symptoms, explained by greater reductions in the qigong group than the control group. Qigong participants had significantly larger increases in serotonin and BDNF, and decreases in cortisol levels, compared with control group participants. Moreover, treatment-related changes in cortisol levels (but not serotonin or BDNF) fully mediated the beneficial effects of qigong on depressive symptoms., Conclusion: The findings provide preliminary evidence that treatment-related changes in cortisol may mediate the benefits of qigong on depressive symptoms. Given the limitation of small sample size of the present study, future studies with larger sample sizes and more extended follow-up assessment are warranted to determine the reliability of these findings., (© 2020 John Wiley & Sons Ltd.)
- Published
- 2020
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28. 4-Coordinated, 14-electron ruthenium(ii) chalcogenolate complexes: synthesis, electronic structure and reactions with PhICl 2 and organic azides.
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Ng WM, Guo X, Cheung WM, So YM, Chong MC, Sung HH, Williams ID, Lin Z, and Leung WH
- Abstract
The 4-coordinated Ru
II chalcogenolate complexes [Ru(STipp)2 (PPh3 )2 ] (Tipp = 2,4,6-triisopropylphenyl, 1) and [Ru(SeMes)2 (PPh3 )2 ] (Mes = 2,4,6-trimethylphenyl, 2) have been synthesized, and their reactions with PhICl2 and organic azides have been studied. Complex 2 synthesized from [RuII (PPh3 )3 Cl2 ] and NaSeMes displays a seesaw structure with P-Ru-P and Se-Ru-Se bond angles of 103.43(13) and 145.26(6)°, respectively. Natural bond order analyses revealed that in each of 1 and 2, there are two n →σ* (donor-acceptor) π interactions between the chalcogen lone pairs and the Ru-P antibonding molecular orbitals. The calculated second-order perturbation interaction energies of the two interactions for 1 (20.5 and 18.3 kcal mol-1 ) are stronger than those of 2 (13.6 and 11.0 kcal mol-1 ), suggesting the thiolate ligand (TippS- ) is a stronger π-donor than the selenolate ligand (MesSe- ) with respect to RuII . Chlorination of 1 with PhICl2 afforded the dichloride complex [Ru(STipp)2 Cl2 (PPh3 )] (3), which was hydrolyzed to the hydroxo complex [Ru(STipp)2 (OH)Cl(PPh3 )] (4) after column chromatography on silica in air. Treatment of 4 with HCl and methyl triflate gave 3 and [Ru(STipp)2 (OH)(OTf)(PPh3 )] (OTf = triflate, 5), respectively. Reactions of 1 and 2 with p-tolyl azide (p-tolN3 ) afforded the tetrazene complexes [Ru{N4 (p-tol)2 }(ER)2 (PPh3 )] (ER = STipp (6), SeMes (7)), whereas that with tosyl azide (TsN3 ) gave the imido complexes [Ru(κ2 -NTs)(STipp)2 (PPh3 )] (ER = STipp (8), SeMes (10)). The short Ru-Nimido distances in 8 [1.883(3) Å] and 10 [1.892(2) Å] are indicative of multiple bond character. Treatment of 8 with TsN3 afforded the tetrazene complex [Ru(N4 Ts2 )(STipp)2 (PPh3 )] (9), but no cycloaddition was found between 10 and TsN3 . Nucleophilic attack of the imido ligand in 10 with methyl triflate yielded the amido complex [Ru(κ2 -NMeTs)(SeMes)2 (PPh3 )](OTf) (11). The crystal structures of 2, 4, 6, and 8-11 have been determined.- Published
- 2019
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29. Reactions of cerium complexes with transition metal nitrides: synthesis and structure of heterometallic cerium complexes containing bridging catecholate ligands.
- Author
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Cheung WM, Au-Yeung KC, Wong KH, So YM, Sung HHY, Williams ID, and Leung WH
- Abstract
In an attempt to synthesize heterometallic cerium nitrido complexes, we studied the reactions of cerium complexes supported by the Kläui tripodal ligand [Co(η
5 -C5 H5 ){PO(OEt)2 }3 ]- (LOEt - ) with transition-metal nitrides. Whereas no reactions were found between Ce-LOEt complexes and [RuVI (LOEt )(N)Cl2 ] (2), treatment of the Ce(iv) oxo complex [CeIV (LOEt )2 (O)(H2 O)]·MeCONH2 (1) with 2 resulted in reduction of both the Ce(iv) and Ru(vi) complexes, and formation of a heterometallic Ce(iii)/Ru(iii) complex with a bridging deprotonated acetamide ligand, [(LOEt )2 (H2 O)CeIII {μ-O,N-MeC(O)NH}RuIII (LOEt )Cl2 ] (4), along with a minor product, [CeIII (LOEt )2 (NO3 )]. Ce(iv)-LOEt complexes such as [CeIV (LOEt )2 Cl2 ] (3) can oxidize [ReV (LOEt )(N)(PPh3 )Cl] to give the Re(vi) nitride [ReVI (LOEt )(N)(PPh3 )Cl]+ . Chloride abstraction of 3 by TlPF6 followed by reaction with [PPh4 ]2 [MnV (N)(CN)4 ] afforded a diamagnetic red solid that is tentatively formulated as a heterometallic Ce(iv)/Mn(v) complex, [Ce(LOEt )2 (H2 O){Mn(N)(CN)4 }] (5). Reactions of 3 with [n Bu4 N][MVI (N)(cat)2 ] (cat2- = catecholate(2-)) afforded the Ce(iii)/M(vi) complexes [(LOEt )2 CeIII {(μ-cat)2 MVI (N)}] [M = Ru (6), Os (7)], in which the Ce(iii) and M(vi) centers are bridged by two oxygen atoms of the two catecholate ligands. Similarly, the catecholate-bridged Ce(iii)/Re(v) complex [(LOEt )2 CeIII {(μ-cat)2 ReV (O)}] (8) was prepared from 3 and [Me4 N][ReV (O)(cat)2 ]. In CH2 Cl2 , 8 was air-oxidized to the Ce(iii)/Re(vii) complex [CeIII (LOEt )2 (H2 O)2 ][cis-{ReVII (O)2 (cat)2 }] (9) with a cis-dioxo-Re(vii) counter-anion. The crystal structures of 4, 6, and 9 have been determined.- Published
- 2019
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30. Iridium porphyrin complexes with μ-nitrido, hydroxo, hydrosulfido and alkynyl ligands.
- Author
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So SC, Cheung WM, Chiu WH, de Vere-Tucker M, Sung HH, Williams ID, and Leung WH
- Abstract
Iridium porphyrin complexes containing μ-nitrido, hydroxo, hydrosulfido, and alkynyl ligands have been synthesized and structurally characterized, and their oxidation has been studied. The alkyl-IrIII porphyrin complex [Ir(tpp)R] (tpp2- = 5,10,15,20-tetraphenylporphyrin dianion; R = C8H13; 1) was synthesized by reaction of [Ir(cod)Cl]2 (cod = 1,5-cyclooctadiene) with H2tpp in refluxing monoethylene glycol. Treatment of 1 with PPh3 and [(LOEt)Ru(N)Cl2] (LOEt- = [(η5-C5H5)Co{P(O)(OEt)2}3]-) gave [Ir(tpp)(R)(PPh3)] (2) and the μ-nitrido complex [R(tpp)Ir(μ-N)RuCl2(LOEt)] (3), respectively. The cyclic voltammogram of 3 exhibited a reversible oxidation couple at 0.44 V versus Fc+/0 (Fc = ferrocene). The oxidation of 3 with [(4-BrC6H4)3N](SbCl6) resulted in Ir-C bond homolysis and formation of the chloride complex [Cl(tpp)Ir(μ-N)RuCl2(LOEt)] (4). The short Ir-N(nitrido) bond distances in 3 [1.944(3) Å] and 4 [1.831(4) Å] are indicative of multiple bond character and thus these two μ-nitrido complexes can be described by the two resonance forms: IrIII-N[triple bond, length as m-dash]RuVI and IrV[double bond, length as m-dash]N[double bond, length as m-dash]RuIV. Similarly, the oxidation of 2 with [(4-BrC6H4)3N](SbCl6) yielded [Ir(tpp)Cl(PPh3)] (5). Chloride abstraction of 5 with TlPF6 in tetrahydrofuran (thf) afforded [Ir(tpp)(PPh3)(thf)](PF6) (6) that reacted with CsOH·H2O and Li2S to give the hydroxo [Ir(tpp)(OH)(PPh3)] (7) and hydrosulfido [Ir(tpp)(PPh3)(SH)] (8) complexes, respectively. Treatment of 6 with phenylacetylene in the presence of CuI and Et3N yielded the bimetallic complex [Ir(tpp)(PPh3)(μ-η1:η2-C[triple bond, length as m-dash]CPh)(CuI)] (9), whereas the transmetallation of 6 with LiC[triple bond, length as m-dash]CPh afforded the mononuclear alkynyl complex [Ir(tpp)(PPh3)(C[triple bond, length as m-dash]CPh)] (10). The electrochemistry of the Ir porphyrin complexes has been studied using cyclic voltammetry. On the basis of the measured redox potentials of [Ir(tpp)(PPh3)X], the ability of X- to stabilize the IrIV state is ranked in the order: R- > PhC[triple bond, length as m-dash]C- > Cl- ∼ OH-. Oxidation of 8 and 9 with [(4-BrC6H4)3N](SbCl6) led to isolation of 5 and [Ir(tpp)(PPh3)(H2O)]+, respectively. The crystal structures of complexes 3, 4, and 7-10 have been determined.
- Published
- 2019
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31. The Neuroscience of Nonpharmacological Traditional Chinese Therapy (NTCT) for Major Depressive Disorder: A Systematic Review and Meta-Analysis.
- Author
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Ye J, Cheung WM, and Tsang HWH
- Abstract
Background: Depression is a common disease affecting a large number of people across the world. Many researchers have focused on treatment for depression based on Western scientific approaches, but research based on traditional Chinese medicine (TCM) interventions, studying its clinical effectiveness and the underlying mechanisms involved, has been limited. The aim of this review is to conduct a pioneering systematic review with meta-analysis of existing studies that investigate the neuroscience basis of nonpharmacological traditional Chinese therapy (NTCT)., Methods: Both English ( Pubmed , Embase , Scopus , SPORTDiscus , PsycINFO ) and Chinese ( China National Knowledge Infrastructure ( CNKI )) databases were searched from inception to October 2018. The effects of NTCT on major depressive disorder, brain activity, and neurophysiological biomarker related outcomes were extracted. Study quality was assessed using the Physiotherapy Evidence Database (PEDro) scale. The effect size of each study was reported by the mean difference of change scores., Results: Six of twelve eligible studies showed that there was a significant improvement in favor of acupuncture in depressive symptoms (SMD -0.69, 95% CI -1.09 to -0.28, p =0.002, I
2 = 73%, p < 0.0008). Based on the available evidence, NTCT including acupuncture, Qigong, and Tai Chi was found to possibly improve brain metabolites, brain activity, and immune and endocrine systems in patients with major depressive disorder., Conclusions: Acupuncture could effectively relieve depressive syndromes. The clinical effects of acupuncture might be attributable to their influence on three proposed pathways, namely, the hypothalamic-pituitary-adrenal (HPA) axis, the locus coeruleus (LC)-immunity pathway, and the negative feedback loop of the hippocampus. Nevertheless, conclusions are limited due to the small number of studies included and the low-quality of the study designs. In the future, a cross-sectional study is needed to test the proposed plausible pathways. PROSPERO registration number is CRD42017080937.- Published
- 2019
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32. An East Meets West Approach to the Understanding of Emotion Dysregulation in Depression: From Perspective to Scientific Evidence.
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Ye J, Cai S, Cheung WM, and Tsang HWH
- Abstract
Depression, an emotion regulation disorder, is a prevalent mental illness in the world. Meanwhile, traditional Chinese medicine (TCM) has been increasingly regarded as a promising and effective alternative therapy approach for patients with depression. Despite many years of research on depression, the current understanding of the pathological mechanism of depression based on TCM theories is still in its infancy. Due to the lack of scientific evidence in the past, TCM is not fully recognized by researchers around the world. This review firstly summarizes the pathogenesis and etiology of depression in terms of both Eastern and Western medical systems. Secondly, it adopts an integrated Eastern and Western approach to propose some plausible neurophysiological pathways linking the liver, spleen, and heart functions explicated in TCM theory. The aim of this theoretical review is to bridge the knowledge gap between Eastern and Western medicine, which may better explain the pathology of depression.
- Published
- 2019
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33. A Nitrido-bridged Heterometallic Ruthenium(IV)/Iron(IV) Phthalocyanine Complex Supported by A Tripodal Oxygen Ligand, [Co(η 5 -C 5 H 5 ){P(O)(OEt) 2 } 3 ] - : Synthesis, Structure, and Its Oxidation to Give Phthalocyanine Cation Radical and Hydroxyphthalocyanine Complexes.
- Author
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Cheung WM, Ng WM, Wong WH, Lee HK, Sung HH, Williams ID, and Leung WH
- Abstract
Dinuclear iron nitrido phthalocyanine complexes are of interest owing to their applications in catalytic oxidation of hydrocarbons. While nitrido-bridged diiron phthalocyanine complexes are well documented, the oxidation chemistry of heterodinuclear iron(IV) phthalocyanine nitrides has not been well explored. In this paper we report on the synthesis of a heterometallic Fe
IV /RuIV phthalocyanine nitride and its oxidation to yield phthalocyanine cation radical and hydroxyphthalocyanine complexes. Treatment of [FeII (Pc)] (Pc2- = phthalocyanine dianion) with [RuVI (LOEt )(N)Cl2 ] (LOEt - = [Co(η5 -C5 H5 ){P(O)(OEt)2 }3 ]- ) (1) afforded the heterometallic μ-nitrido complex [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc)(H2 O)] (2) that contains an RuIV =N = FeIV linkage with the Ru-N and Fe-N distances of 1.689(6) and 1.677(6) Å, respectively, and Ru-N-Fe angle of 176.0(4)°. Substitution of 2 with 4- tert-butylpyridine (Bupy) gave [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc)(Bupy)]. The cyclic voltammogram of 2 displayed a reversible Pc-centered oxidation couple at +0.18 V versus Fc+/0 (Fc = ferrocene). The oxidation of 2 with [N(4-BrC6 H4 )3 ]SbCl6 led to isolation of the cationic complex [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc·+ )(H2 O)][SbCl6 ]0.85 [SbCl5 (OH)]0.15 (2[SbCl6 ]0.85 [SbCl5 (OH)]0.15 ), whereas that with PhICl2 yielded the chloride complex [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc·+ )Cl] (3). Complexes 2[SbCl6 ]0.85 [SbCl5 (OH)]0.15 and 3 have been characterized by X-ray crystallography. The UV/visible spectra of 2+ (λmax = 515 and 747 nm) and 3 (λmax = 506 and 748 nm) displayed absorption bands that are characteristic of Pc cation radical. The EPR spectrum of 3 showed a signal with the g value of 2.0012 (width = 5 G) that is consistent with an organic radical. The spectroscopic data support the formulation of 2+ and 3 as RuIV -FeIV Pc cation radical complexes. The reaction of 2 with PhI(CF3 CO2 )2 in dried CH2 Cl2 afforded a mixture of [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc·+ )(CF3 CO2 )] (4) and a hydroxyphthalocyanine complex, [Cl2 (LOEt )RuIV (μ-N)FeIV (Pc-OH)(H2 O)](CF3 CO2 ) (5), whereas that in wet CH2 Cl2 (containing ca. 0.5% water) led to isolation of 5 as the sole product. Complex 4 was independently prepared by salt metathesis of 3 with AgCF3 CO2 .- Published
- 2018
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34. Clinacanthus nutans Mitigates Neuronal Apoptosis and Ischemic Brain Damage Through Augmenting the C/EBPβ-Driven PPAR-γ Transcription.
- Author
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Wu JS, Kao MH, Tsai HD, Cheung WM, Chen JJ, Ong WY, Sun GY, and Lin TN
- Subjects
- Animals, Cells, Cultured, Injections, Intraperitoneal, Male, Mice, Inbred BALB C, Neurons drug effects, Neurons metabolism, Plant Extracts pharmacology, Rats, Acanthaceae chemistry, Apoptosis drug effects, Brain Ischemia genetics, Brain Ischemia pathology, CCAAT-Enhancer-Binding Protein-beta metabolism, Neurons pathology, PPAR gamma metabolism, Transcription, Genetic drug effects
- Abstract
Clinacanthus nutans Lindau (C. nutans) is a traditional herbal medicine widely used in Asian countries for treating a number of remedies including snake and insect bites, skin rashes, viral infections, and cancer. However, the underlying molecular mechanisms for its action and whether C. nutans can offer protection on stroke damage in brain remain largely unknown. In the present study, we demonstrated protective effects of C. nutans extract to ameliorate neuronal apoptotic death in the oxygen-glucose deprivation model and to reduce infarction and mitigate functional deficits in the middle cerebral artery occlusion model, either administered before or after hypoxic/ischemic insult. Using pharmacological antagonist and siRNA knockdown approaches, we demonstrated ability for C. nutans extract to protect neurons and ameliorate ischemic injury through promoting the anti-apoptotic activity of peroxisome proliferator-activated receptor-gamma (PPAR-γ), a stress-induced transcription factor. Reporter and chromatin immunoprecipitation promoter analysis further revealed C. nutans extract to selectively increase CCAAT/enhancer binding protein (C/EBP)β binding to specific C/EBP binding site (-332~-325) on the PPAR-γ promoter to augment its transcription. In summary, we report a novel transcriptional activation involving C/EBPβ upregulation of PPAR-γ expression to suppress ischemic neuronal apoptosis and brain infarct. Recognition of C. nutans to enhance the C/EBPβ → PPAR-γ neuroprotective signaling pathway paves a new way for future drug development for prevention and treatment of ischemic stroke and other neurodegenerative diseases.
- Published
- 2018
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35. Creation of quasi-Dirac points in the Floquet band structure of bilayer graphene.
- Author
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Cheung WM and Chan KS
- Abstract
We study the Floquet quasi-energy band structure of bilayer graphene when it is illuminated by two laser lights with frequencies [Formula: see text] and [Formula: see text] using Floquet theory. We focus on the dynamical gap formed by the conduction band with Floquet index = -1 and the valence band with Floquet index = +1 to understand how Dirac points can be formed. It is found that the dynamical gap does not have rotation symmetry in the momentum space, and quasi-Dirac points, where the conduction and valence bands almost touch, can be created when the dynamical gap closes along some directions with suitably chosen radiation parameters. We derive analytical expressions for the direction dependence of the dynamical gaps using Lowdin perturbation theory to gain a better understanding of the formation of quasi-Dirac points. When both radiations are circularly polarized, the gap can be exactly zero along some directions, when only the first and second order perturbations are considered. Higher order perturbations can open a very small gap in this case. When both radiations are linearly polarized, the gap can be exactly zero up to the fourth order perturbation and more than one quasi-Dirac point is formed. We also study the electron velocity around a dynamical gap and show that the magnitude of the velocity drops to values close to zero when the k vector is near to the gap minimum. The direction of the velocity also changes around the gap minimum, and when the gap is larger in value the change in the velocity direction is more gradual. The warping effect does not affect the formation of a Dirac point along the k
x axis, while it prevents its formation when there is phase shift between the two radiations.- Published
- 2017
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36. Heterobimetallic Nitrido Complexes of Group 8 Metalloporphyrins.
- Author
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Cheung WM, Chiu WH, de Vere-Tucker M, Sung HH, Williams ID, and Leung WH
- Abstract
Heterobimetallic nitrido porphyrin complexes with the [(L)(por)M-N-M'(L
OEt )Cl2 ] formula {por2- = 5,10,15,20-tetraphenylporphyrin (TPP2- ) or 5,10,15,20-tetra(p-tolyl)porphyrin (TTP2- ) dianion; LOEt - = [Co(η5 -C5 H5 ){P(O)(OEt)2 }3 ]- ; M = Fe, Ru, or Os; M' = Ru or Os; L = H2 O or pyridine} have been synthesized, and their electrochemistry has been studied. Treatment of trans-[Fe(TPP)(py)2 ] (py = pyridine) with Ru(VI) nitride [Ru(LOEt )(N)Cl2 ] (1) afforded Fe/Ru μ-nitrido complex [(py)(TPP)Fe(μ-N)Ru(LOEt )Cl2 ] (2). Similarly, Fe/Os analogue [(py)(TPP)Fe(μ-N)Os(LOEt )Cl2 ] (3) was obtained from trans-[Fe(TPP)(py)2 ] and [Os(LOEt )(N)Cl2 ]. However, no reaction was found between trans-[Fe(TPP)(py)2 ] and [Re(LOEt )(N)Cl(PPh3 )]. Treatment of trans-[M(TPP)(CO)(EtOH)] with 1 afforded μ-nitrido complexes [(H2 O)(TPP)M(μ-N)Ru(LOEt )Cl2 ] [M = Ru (4a) or Os (5)]. TTP analogue [(H2 O)(TTP)Ru(μ-N)Ru(LOEt )Cl2 ] (4b) was prepared similarly from trans-[Ru(TTP)(CO)(EtOH)] and 1. Reaction of [(H2 O)(por)M(μ-N)M(LOEt )Cl2 ] with pyridine gave adducts [(py)(por)M(μ-N)Ru(LOEt )Cl2 ] [por = TTP, and M = Ru (6); por = TPP, and M = Os (7)]. The diamagnetism and short (por)M-N(nitride) distances in 2 [Fe-N, 1.683(3) Å] and 4b [Ru-N, 1.743(3) Å] are indicative of the MIV ═N═M'IV bonding description. The cyclic voltammograms of the Fe/Ru (2) and Ru/Ru (4b) complexes in CH2 Cl2 displayed oxidation couples at approximately +0.29 and +0.35 V versus Fc+/0 (Fc = ferrocene) that are tentatively ascribed to the oxidation of the {LOEt Ru} and {Ru(TTP)} moieties, respectively, whereas the Fe/Os (3) and Os/Ru (5) complexes exhibited Os-centered oxidation at approximately -0.06 and +0.05 V versus Fc+/0 , respectively. The crystal structures of 2 and 4b have been determined.- Published
- 2017
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37. PPAR-γ Ameliorates Neuronal Apoptosis and Ischemic Brain Injury via Suppressing NF-κB-Driven p22phox Transcription.
- Author
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Wu JS, Tsai HD, Cheung WM, Hsu CY, and Lin TN
- Subjects
- Animals, Base Sequence, Brain Ischemia complications, Brain Ischemia drug therapy, Brain Ischemia metabolism, Cell Nucleus drug effects, Cell Nucleus metabolism, Cells, Cultured, Cerebral Cortex pathology, Cerebral Infarction complications, Cerebral Infarction drug therapy, Cerebral Infarction pathology, Cytosol metabolism, Down-Regulation drug effects, Glucose deficiency, Male, Mice, Neurons drug effects, Neurons metabolism, Oxidation-Reduction, Oxygen, Promoter Regions, Genetic genetics, Prostaglandin D2 analogs & derivatives, Prostaglandin D2 pharmacology, Prostaglandin D2 therapeutic use, Protein Binding drug effects, Protein Transport drug effects, RNA, Small Interfering metabolism, Rats, Long-Evans, Reactive Oxygen Species metabolism, Apoptosis drug effects, Brain Ischemia pathology, Cytochrome b Group metabolism, NADPH Oxidases metabolism, NF-kappa B metabolism, Neurons pathology, PPAR gamma metabolism, Transcription, Genetic drug effects
- Abstract
Peroxisome proliferator-activated receptor-gamma (PPAR-γ), a stress-induced transcription factor, protects neurons against ischemic stroke insult by reducing oxidative stress. NADPH oxidase (NOX) activation, a major driving force in ROS generation in the setting of reoxygenation/reperfusion, constitutes an important pathogenetic mechanism of ischemic brain damage. In the present study, both transient in vitro oxygen-glucose deprivation and in vivo middle cerebral artery (MCA) occlusion-reperfusion experimental paradigms of ischemic neuronal death were used to investigate the interaction between PPAR-γ and NOX. With pharmacological (PPAR-γ antagonist GW9662), loss-of-function (PPAR-γ siRNA), and gain-of-function (Ad-PPAR-γ) approaches, we first demonstrated that 15-deoxy-∆(12,14)-PGJ2 (15d-PGJ2), via selectively attenuating p22phox expression, inhibited NOX activation and the subsequent ROS generation and neuronal death in a PPAR-γ-dependent manner. Secondly, results of promoter analyses and subcellular localization studies further revealed that PPAR-γ, via inhibiting hypoxia-induced NF-κB nuclear translocation, indirectly suppressed NF-κB-driven p22phox transcription. Noteworthily, postischemic p22phox siRNA treatment not only reduced infarct volumes but also improved functional outcome. In summary, we report a novel transrepression mechanism involving PPAR-γ downregulation of p22phox expression to suppress the subsequent NOX activation, ischemic neuronal death, and brain infarct. Identification of a PPAR-γ → NF-κB → p22phox neuroprotective signaling cascade opens a new avenue for protecting the brain against ischemic insult.
- Published
- 2016
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38. Psychosomatic and physical responses to a multi-component stress management program among teaching professionals: A randomized study of cognitive behavioral intervention (CB) with complementary and alternative medicine (CAM) approach.
- Author
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Au DW, Tsang HW, Lee JL, Leung CH, Lo JY, Ngai SP, and Cheung WM
- Subjects
- Adaptation, Psychological, Adult, Complementary Therapies methods, Female, Hong Kong, Humans, Male, Meditation psychology, Middle Aged, Relaxation Therapy methods, Stress, Psychological psychology, Surveys and Questionnaires, Cognitive Behavioral Therapy methods, School Teachers psychology, Stress, Psychological therapy
- Abstract
Background: The present study aims to assess psychosomatic and physical responses to a multi-component stress management program with the use of CAM and CB approaches among teaching professionals in Hong Kong., Method: A random controlled trial (RCT) was used to compare between CB group (n = 26) and the CAM-CB group (n = 30). Interventions were administered for 1.5 h once a week for eight consecutive weeks. A self-administered questionnaire including perceived stress scale (PSS) and frequency of psychosomatic symptoms were measured at baseline (T1), immediate after the program (T2), and 4 weeks after the program (T3). Physical parameters were measured at T1 and T2., Results: A reduction of 23% in PSS was observed in the CB group, while the CAM-CB group yielded 18% reductions in PSS from T1 to T3 [F(2,108) = 3.099; p = .049]. No significant interactions were observed in the frequency of psychosomatic symptoms and physical parameters. However, a significant downward time trend was observed (p < .001) and larger percentage changes in physical responses were shown in the CAM-CB group than CB group., Conclusion: Clinical evidence of both the CAM-CB and CB program has been demonstrated in the current study and both approaches are easy to be self-implemented. The CAM technique might serve as an alternative choice for self-administered stress management to replace the additional time needed for professional follow-up contacts. It might further improve some physical responses such as handgrip strength and resting heart rate, which are associated with better psychosomatic health and better occupational stress management., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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39. Ruthenium chalcogenonitrosyl and bridged nitrido complexes containing chelating sulfur and oxygen ligands.
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Ng HY, Cheung WM, Kwan Huang E, Wong KL, Sung HH, Williams ID, and Leung WH
- Abstract
Ruthenium thio- and seleno-nitrosyl complexes containing chelating sulfur and oxygen ligands have been synthesised and their de-chalcogenation reactions have been studied. The reaction of mer-[Ru(N)Cl3(AsPh3)2] with elemental sulfur and selenium in tetrahydrofuran at reflux afforded the chalcogenonitrosyl complexes mer-[Ru(NX)Cl3(AsPh3)2] [X = S (1), Se (2)]. Treatment of 1 with KN(R2PS)2 afforded trans-[Ru(NS)Cl{N(R2PS)2}2] [R = Ph (3), Pr(i) (4), Bu(t) (5)]. Alternatively, the thionitrosyl complex 5 was obtained from [Bu(n)4N][Ru(N)Cl4] and KN(Bu(t)2PS)2, presumably via sulfur atom transfer from [N(Bu(t)2PS)2](-) to the nitride. Reactions of 1 and 2 with NaLOEt (LOEt(-) = [Co(η(5)-C5H5){P(O)(LOEt)2}3](-)) gave [Ru(NX)LOEtCl2] (X = S (8), Se (9)). Treatment of [Bu(n)4N][Ru(N)Cl4] with KN(R2PS)2 produced Ru(IV)-Ru(IV)μ-nitrido complexes [Ru2(μ-N){N(R2PS)2}4Cl] [R = Ph (6), Pr(i) (7)]. Reactions of 3 and 9 with PPh3 afforded 6 and [Ru(NPPh3)LOEtCl2], respectively. The desulfurisation of 5 with [Ni(cod)2] (cod = 1,5-cyclooctadiene) gave the mixed valance Ru(III)-Ru(IV)μ-nitrido complex [Ru2(μ-N){N(Bu(t)2PS)2}4] (10) that was oxidised by [Cp2Fe](PF6) to give the Ru(IV)-Ru(IV) complex [Ru2(μ-N){N(Bu(t)2PS)2}4](PF6) ([10]PF6). The crystal structures of 1, 2, 3, 7, 9 and 10 have been determined.
- Published
- 2015
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40. Effects of acupressure on anxiety: a systematic review and meta-analysis.
- Author
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Au DW, Tsang HW, Ling PP, Leung CH, Ip PK, and Cheung WM
- Subjects
- Adult, Anxiety, Humans, Acupressure
- Abstract
Objective: To evaluate the evidence from randomised controlled trials (RCTs) and quantify the effects of acupressure on anxiety among adults., Methodology: RCTs published between January 1997 and February 2014, comparing acupressure with sham control, were identified from the databases Science Citation Index/Social Sciences Citation Index, Scopus, PubMed and PsycINFO. Meta-analysis of eligible studies was performed and the magnitude of the overall effect size was calculated for the anxiety outcome. Revised STRICTA (the Standards for Reporting Interventions in Clinical Trials of Acupuncture) criteria were used to appraise the acupressure procedures, and the Cochrane risk of bias tool was used to assess the methodological quality of the studies., Results: Of 39 potentially relevant studies, seven RCTs met the inclusion criteria for review while five studies met the criteria for meta-analysis. All studies reported the positive effect of acupressure on relieving anxiety from the anticipation of surgery or treatment. EX-HN3 (Yintang), HT7 (Shenmen) were the commonest points selected and two studies used bilateral points. The acupressure procedure was generally well reported and studies had a low risk of bias. The combined results of the five trials showed a greater overall reduction in anxiety in the acupressure group than in the sham controls (standardised mean differences (SMD)=-1.11; 95% CI -1.61 to -0.61; p<0.0001 heterogeneity: I(2)=75%; χ(2)=16.17; p=0.003; r=0.485)., Conclusions: Acupressure seems to be effective in providing immediate relief of pretreatment anxiety among adults, and has a medium effect size. However, conflicting results were found for the improvements on physiological indicators. More rigorous reporting, including allocation concealment procedure, is needed to strengthen the results., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)
- Published
- 2015
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41. Next generation genome sequencing reveals phylogenetic clades with different level of virulence among Salmonella Typhimurium clinical human isolates in Hong Kong.
- Author
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Cheng CK, Cheung MK, Nong W, Law PT, Qin J, Ling JM, Kam KM, Cheung WM, and Kwan HS
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Anti-Bacterial Agents pharmacology, Child, Child, Preschool, Drug Resistance, Bacterial, Female, High-Throughput Nucleotide Sequencing, Hong Kong epidemiology, Humans, Infant, Male, Microbial Sensitivity Tests, Middle Aged, Polymorphism, Single Nucleotide, Salmonella Infections epidemiology, Salmonella typhimurium drug effects, Salmonella typhimurium isolation & purification, Salmonella typhimurium pathogenicity, Virulence genetics, Young Adult, Genome, Bacterial, Genotype, Phylogeny, Salmonella Infections microbiology, Salmonella typhimurium classification, Salmonella typhimurium genetics
- Abstract
Background: Salmonella Typhimurium is frequently isolated from foodborne infection cases in Hong Kong, but the lack of genome sequences has hindered in-depth epidemiological and phylogenetic studies. In this study, we sought to reconstruct the phylogenetic relationship and investigate the distribution and mutation patterns of virulence determinants among local S. Typhimurium clinical isolates using their genome sequences., Results: We obtained genome sequences of 20 S. Typhimurium clinical isolates from a local hospital cluster using a 454 GS FLX Titanium sequencing platform. Phylogenetic analysis was performed based on single nucleotide polymorphism positions of the core genome against the reference strain LT2. Antimicrobial susceptibility was determined using minimal inhibitory concentration for five antimicrobial agents and analyses of virulence determinants were performed through referencing to various databases. Through phylogenetic analysis, we revealed two distinct clades of S. Typhimurium isolates and three outliers in Hong Kong, which differ remarkably in antimicrobial susceptibility and presentation and mutations of virulence determinants. The local isolates were not closely related to many of the previously sequenced S. Typhimurium isolates, except LT2. As the isolates in the two clades spanned over 10 years of isolation, they probably represent endemic strains. The outliers are possibly introduced from outside of Hong Kong. The close relatedness of members in one of the clades to LT2 and the Japanese stool isolate T000240 suggests the potential reemergence of LT2 progeny in regions nearby., Conclusions: Our study demonstrated the utility of next-generation sequencing coupled to traditional microbiological testing method in a retrospective epidemiological study involving multiple clinical isolates. The evolution of multidrug- and ciprofloxacin-resistant strains among the more virulent clade is also an increasing concern.
- Published
- 2015
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42. Heterobimetallic rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η(5)-C5H5){P(O)(OEt)2}3](-).
- Author
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So YM, Chiu WH, Cheung WM, Ng HY, Lee HK, Sung HH, Williams ID, and Leung WH
- Abstract
Rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η(5)-C5H5){P(O)(OEt)2}3](-) (LOEt(-)) have been synthesised and their reactions with [Ir(I)(cod)Cl]2 (cod = 1,5-cyclooctadiene) and [Rh(II)2(OAc)4] (OAc(-) = acetate) have been studied. The treatment of [Bu(n)4N][Re(VI)(N)Cl4] with NaLOEt in methanol afforded the Re(VI) nitride [Re(VI)(LOEt)(N)Cl(OMe)] (1). Reactions of 1 with [Ir(I)(cod)Cl]2 and [Rh(II)2(OAc)4] gave the μ-nitrido complexes [(LOEt)(OMe)ClRe(VI)(μ-N)Ir(I)(cod)Cl] (2) and [Rh(II)2(OAc)4{(μ-N)Re(VI)(LOEt)(OMe)Cl}2] (4), respectively. [(LOEt)Cl(PPh3)Re(V)(μ-N)Ir(I)(cod)Cl] (3) and [(LOEt)Cl(PPh3)Re(VI)(μ-N)Ir(I)(cod)Cl][PF6] (3·PF6) have been synthesised from the reactions of [Ir(I)(cod)Cl]2 with [Re(V)LOEt(N)Cl(PPh3)] and [Re(VI)LOEt(N)Cl(PPh3)](PF6), respectively. Similarly, the redox pair [Rh(II)2(OAc)4{(μ-N)Re(V)(LOEt)(PPh3)Cl}2] (5) and [Rh(II)2(OAc)4{(μ-N)Re(VI)(LOEt)(PPh3)Cl}2](PF6)2 (·(PF6)2) have been synthesised from the reactions of [Rh2(OAc)4] with [Re(V)LOEt(N)Cl(PPh3)] and [Re(VI)LOEt(N)Cl(PPh3)](PF6), respectively. While [(LOEt)Cl2Ru(VI)(μ-N)Ir(I)(cod)] (6) was obtained from [Ru(VI)(LOEt)(N)Cl2] and [Ir(I)(cod)Cl]2, the interaction between [Ru(VI)(LOEt)(N)Cl2] and [Rh(II)2(OAc)4] in CH2Cl2 is reversible. The crystal structures of complexes 2, 3, 3·PF6, 5, 5·(PF6)2 and 6 have been determined. X-ray crystallography indicates that the nitrido bridges in 2, 3, 3·PF6 and 6 can be described as MN-Ir (M = Re, Ru) showing Ir-N multiple bond character, whereas the interaction between Re≡N and Rh in 5 and 5·(PF6)2 is mostly of the donor-acceptor type. The electrochemistry of the Re nitrido complexes has been investigated by cyclic voltammetry.
- Published
- 2015
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43. A pilot evaluation on a stress management programme using a combined approach of cognitive behavioural therapy (CBT) and complementary and alternative medicine (CAM) for elementary school teachers.
- Author
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Tsang HW, Cheung WM, Chan AH, Fung KM, Leung AY, and Au DW
- Subjects
- Adaptation, Psychological, Adult, Aromatherapy, Female, Hong Kong, Humans, Job Satisfaction, Male, Meditation, Middle Aged, Pilot Projects, Relaxation Therapy, Self Care, Anxiety therapy, Cognitive Behavioral Therapy methods, Complementary Therapies methods, Depression therapy, Faculty, Stress, Psychological therapy
- Abstract
The aim of this study is to explore the efficacy of implementing a stress management programme based on a combined approach using cognitive behavioural therapy and complementary and alternative medicine for elementary school teachers who experienced mild level of stress, anxiety and/or depressive symptoms in Hong Kong. A 12-h programme involving cognitive behavioural therapy, self-management, relaxation techniques (diaphragmatic breathing and progressive muscle relaxation), mindful exercises (qigong and yoga), aromatherapy and acupressure was conducted. A quasi-experimental design was used to compare the intervention groups (n = 47) with the wait-list control groups (n = 46). The primary outcome measures were depression, anxiety and stress. Results indicated that the intervention group had significant reduction in depression [(F = 3.93; degrees of freedom (df) = 2.90; p = 0.023)], anxiety (F = 3.37; df = 2.90; p = 0.039) and stress (F = 3.63; df = 2.89; p = 0.031) when compared with the control group. Participants in both groups demonstrated lowered level of salivary cortisol at the post-assessment. The pilot results provided preliminary support to the multi-component stress management programme in relieving affective symptoms of teachers. The programme may be considered as an initial strategy to empower teachers with the abilities to cope with their affective symptoms. Further evaluation using a better designed randomized study with a larger sample size is warranted. (word: 198; max.: 200)., (© 2013 John Wiley & Sons, Ltd.)
- Published
- 2015
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44. Anti-proliferative activities of sinigrin on carcinogen-induced hepatotoxicity in rats.
- Author
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Jie M, Cheung WM, Yu V, Zhou Y, Tong PH, and Ho JW
- Subjects
- Animals, Cell Line, Tumor, Cell Proliferation drug effects, G1 Phase Cell Cycle Checkpoints drug effects, Gene Expression Regulation, Neoplastic drug effects, Humans, Liver metabolism, Liver pathology, Liver Neoplasms chemically induced, Liver Neoplasms genetics, Male, Proto-Oncogene Proteins c-mdm2 genetics, RNA, Messenger genetics, RNA, Messenger metabolism, Rats, Rats, Sprague-Dawley, Resting Phase, Cell Cycle drug effects, Tumor Suppressor Protein p53 genetics, Xenograft Model Antitumor Assays, Antineoplastic Agents pharmacology, Carcinogens toxicity, Glucosinolates pharmacology, Liver drug effects, Liver Neoplasms pathology
- Abstract
Liver cancer is one of the leading causes of cancer death worldwide. A very high incidence of new liver cancer cases is diagnosed every year, and metastasis has been found to correlate to poor prognoses in humans. Better treatments for liver cancer are thus clearly needed. Sinigrin is one of the major ingredients present in Brassica nigra, which has been used in combination with other herbs for treatment of various diseases. The anti-proliferative activities of sinigrin were studied in a model of carcinogen-induced hepatotoxicity in rats. Rats were orally administered with sinigrin on a daily basis for three months before sacrifice. Sinigrin was found to significantly inhibit the proliferation of liver tumor cells; the number of surface tumors in the rat liver was dramatically reduced. Sinigrin induced apoptosis of liver cancer cells through up-regulation of p53 and down-regulation of Bcl-2 family members and caspases. Our findings indicated that the liver functions were gradually restored after treatment with sinigrin and that the agent did not cause liver toxicity. Cell cycle analysis indicated that sinigrin caused cell cycle arrest in G0/G1 phase. The results suggest that sinigrin exerts important anti-proliferative activities in carcinogen-induced hepatocarcinogenesis in rats, and highlight the potential of sinigrin as an anti-cancer agent for liver cancer.
- Published
- 2014
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45. Disturbed flow promotes endothelial senescence via a p53-dependent pathway.
- Author
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Warboys CM, de Luca A, Amini N, Luong L, Duckles H, Hsiao S, White A, Biswas S, Khamis R, Chong CK, Cheung WM, Sherwin SJ, Bennett MR, Gil J, Mason JC, Haskard DO, and Evans PC
- Subjects
- Animals, Aortic Diseases genetics, Aortic Diseases pathology, Aortic Diseases physiopathology, Atherosclerosis genetics, Atherosclerosis pathology, Atherosclerosis physiopathology, Bioreactors, Cell Movement, Cells, Cultured, Cyclin-Dependent Kinase Inhibitor p21 genetics, Cyclin-Dependent Kinase Inhibitor p21 metabolism, Diet, High-Fat, Disease Models, Animal, Endothelial Cells drug effects, Endothelial Cells pathology, Enzyme Activation, Enzyme Activators pharmacology, Human Umbilical Vein Endothelial Cells metabolism, Human Umbilical Vein Endothelial Cells pathology, Humans, Mice, Mice, Inbred C57BL, Mice, Knockout, RNA Interference, Receptors, LDL deficiency, Receptors, LDL genetics, Regional Blood Flow, Sirtuin 1 metabolism, Stress, Mechanical, Swine, Time Factors, Transfection, Tumor Suppressor Protein p53 genetics, Wound Healing, Aortic Diseases metabolism, Atherosclerosis metabolism, Cellular Senescence drug effects, Endothelial Cells metabolism, Mechanotransduction, Cellular drug effects, Tumor Suppressor Protein p53 metabolism
- Abstract
Objective: Although atherosclerosis is associated with systemic risk factors such as age, high cholesterol, and obesity, plaque formation occurs predominately at branches and bends that are exposed to disturbed patterns of blood flow. The molecular mechanisms that link disturbed flow-generated mechanical forces with arterial injury are uncertain. To illuminate them, we investigated the effects of flow on endothelial cell (EC) senescence., Approach and Results: LDLR(-/-) (low-density lipoprotein receptor(-/-)) mice were exposed to a high-fat diet for 2 to 12 weeks (or to a normal chow diet as a control) before the assessment of cellular senescence in aortic ECs. En face staining revealed that senescence-associated β-galactosidase activity and p53 expression were elevated in ECs at sites of disturbed flow in response to a high-fat diet. By contrast, ECs exposed to undisturbed flow did not express senescence-associated β-galactosidase or p53. Studies of aortae from healthy pigs (aged 6 months) also revealed enhanced senescence-associated β-galactosidase staining at sites of disturbed flow. These data suggest that senescent ECs accumulate at disturbed flow sites during atherogenesis. We used in vitro flow systems to examine whether a causal relationship exists between flow and EC senescence. Exposure of cultured ECs to flow (using either an orbital shaker or a syringe-pump flow bioreactor) revealed that disturbed flow promoted EC senescence compared with static conditions, whereas undisturbed flow reduced senescence. Gene silencing studies demonstrated that disturbed flow induced EC senescence via a p53-p21 signaling pathway. Disturbed flow-induced senescent ECs exhibited reduced migration compared with nonsenescent ECs in a scratch wound closure assay, and thus may be defective for arterial repair. However, pharmacological activation of sirtuin 1 (using resveratrol or SRT1720) protected ECs from disturbed flow-induced senescence., Conclusions: Disturbed flow promotes endothelial senescence via a p53-p21-dependent pathway which can be inhibited by activation of sirtuin 1. These observations support the principle that pharmacological activation of sirtuin 1 may promote cardiovascular health by suppressing EC senescence at atheroprone sites.
- Published
- 2014
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46. Enhancement of doxorubicin cytotoxicity by tanshinone IIA in HepG2 human hepatoma cells.
- Author
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Kan S, Cheung WM, Zhou Y, and Ho WS
- Subjects
- Antineoplastic Agents, Phytogenic administration & dosage, Antineoplastic Agents, Phytogenic pharmacology, Antioxidants pharmacology, Benzofurans administration & dosage, Caspase 3 metabolism, Chlorogenic Acid administration & dosage, Doxorubicin administration & dosage, Hep G2 Cells drug effects, Humans, L-Lactate Dehydrogenase metabolism, NADPH Oxidase 4, NADPH Oxidases metabolism, Reactive Oxygen Species metabolism, Abietanes administration & dosage, Abietanes pharmacology, Antineoplastic Combined Chemotherapy Protocols pharmacology
- Abstract
Chlorogenic acid (1), salvianolic acid B (2), and tanshinone IIA (3) are commonly used as chemoprotective agents for chemotherapy in cancer patients. The present study deals with the effect of these three compounds on cytotoxicity of doxorubicin in HepG2 cells. The results showed that 1 and 2 reduced the cytotoxicity of doxorubicin through scavenging ROS generated by doxorubicin in HepG2 cells. The findings suggest that 1 and 2 could enhance the expression of SOD and decrease that of NADPH oxidase, which resulted in the elimination of ROS. On the contrary, 3 enhanced the cytotoxicity of doxorubicin in HepG2 cells. Furthermore, drug interactions between doxorubicin and 3 produce synergistic effects in HepG2 cells., (Georg Thieme Verlag KG Stuttgart · New York.)
- Published
- 2014
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47. Genome Sequences of Salmonella enterica Serotype Typhimurium Blood Clinical Isolate ST4848/06 and Stool Isolate ST1489/06.
- Author
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Cheng CK, Au CH, Li L, Nong W, Law PT, Cheung WM, Ling JM, and Kwan HS
- Abstract
Salmonella enterica serotype Typhimurium human blood strains isolated from outside Africa are rarely sequenced. Here, we report the draft genome sequences of two S. Typhimurium clinical strains isolated in the same year, one from blood and another from stool, in order to gain insights into the genetic basis leading to invasive diseases.
- Published
- 2013
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48. Facile η5-η1 ring slippage of the cycloolefin ligands in osmocene and bis(η5-indenyl)ruthenium(II).
- Author
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Cheung WM, Huang EK, Zhu J, Yi XY, Sung HH, Williams ID, and Leung WH
- Abstract
η(5)-η(1) ring slippage of [OsCp2] (Cp = η(5)-C5H5) and [Ru(η(5)-ind)2] (ind = indenyl) resulting from reaction with the ruthenium(VI) nitride [Ru(L(OEt))(N)Cl2] (1; L(OEt)(-) = [CoCp{P(O)(OEt)2}3](-)) is reported. The treatment of [OsCp2] or [Ru(η(5)-ind)2] with 1 resulted in η(5)-η(1) ring slippage of the cycloolefin ligands and formation of the trinuclear nitrido complexes [Cp(η(1)-C5H5)Os(NRuL(OEt)Cl2)2] (2) or [(η(5)-ind)(η(1)-ind)Ru(NRuL(OEt)Cl2)2] (3). No reactions were found between [OsCp2] and amines, such as pyridine and 2,2'-bipyridyl, or other metal nitrides, such as [Os(L(OEt))(N)Cl2], indicating that the electrophilic property of 1 is essential for ring slippage. The crystal structures of 2 and 3 have been determined. The short Os-N distances in 2 [1.833(5) and 1.817(5) Å] and the (ind)Ru-N distances in 3 [1.827(5) and 1.852(5) Å] are indicative of multiple bond character, consistent with density functional theory (DFT) calculations. Therefore, 2 and 3 may be described by two resonance forms: Ru(VI)-M(II)-Ru(VI) and Ru(IV)-M(VI)-Ru(IV) (M = Os, Ru). Also, DFT calculations indicate that for the reaction of 1 with [OsCp2] or [Ru(η(5)-ind)2], η(5)-η(1) ring slippage is energetically more favorable than the η(5)-η(3) counterpart. The driving force for η(5)-η(1) ring slippage is believed to be the formation of the strong M-N (M = Os, Ru) (multiple) bonds. By contrast, the same reaction with acetonitrile is energetically uphill, and thus no ring slippage occurs.
- Published
- 2013
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49. Draft genome sequence of Salmonella enterica serovar Typhimurium ST1660/06, a multidrug-resistant clinical strain isolated from a diarrheic patient.
- Author
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Li L, Cheng CK, Cheung MK, Law PT, Ling JM, Kam KM, Cheung WM, and Kwan HS
- Subjects
- Drug Resistance, Multiple, Bacterial, Humans, Molecular Sequence Data, Salmonella typhimurium classification, Anti-Bacterial Agents pharmacology, Diarrhea microbiology, Genome, Bacterial, Salmonella Infections microbiology, Salmonella typhimurium drug effects, Salmonella typhimurium genetics
- Abstract
Salmonella enterica serovar Typhimurium is one of the most prevalent serovars of Salmonella that causes human gastroenteritis. Here, we report the draft genome sequence of the S. Typhimurium multidrug-resistant strain ST1660/06. Comparative genomic analysis unveiled three strain-specific genomic islands that potentially confer the multidrug resistance and virulence of the strain.
- Published
- 2012
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50. Dinuclear ruthenium nitrido complexes supported by an oxygen tripodal ligand.
- Author
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Yi XY, Ng HY, Cheung WM, Sung HH, Williams ID, and Leung WH
- Abstract
Dinuclear ruthenium nitrido complexes supported by the Kläui's tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized starting from the ruthenium(VI) nitrido precursor [L(OEt)Ru(VI)(N)Cl(2)] (1). Heating a solution of 1 in CCl(4) at reflux, followed by recrystallization from hexane under nitrogen, afforded the mixed-valence ruthenium(V)-ruthenium(IV) μ-nitrido complex [L(OEt)Cl(2)Ru(V)(μ-N)Ru(IV)Cl(2)L(OEt)] (2). The cyclic voltammogram of 2 exhibited reversible couples at 0.19 and 1.13 V versus Cp(2)Fe(+/0), which are assigned as the Ru(V)-Ru(IV)/Ru(IV)-Ru(IV) and Ru(V)-Ru(V)/Ru(V)-Ru(IV) couples, respectively. Recrystallization of 2 from Et(2)O/heptane in air yielded the diamagnetic Ru(IV)-Ru(IV) complex [H(13)O(6)][{L(OEt)Ru(IV)Cl(2)}(2)(μ-N)] ([H(13)O(6)][2]), which underwent cation exchange with n-Bu(4)NOH to give [n-Bu(4)N][2]. X-ray diffraction revealed that the complex anions in [H(13)O(6)][2] and [n-Bu(4)N][2] contain linear, symmetric Ru-N-Ru bridges. Treatment of 1 with [(η(6)-p-cymene)Ru(II)Cl(2)](2) in benzene afforded the tetranuclear ruthenium(IV) complex [L(OEt)Cl(2)Ru(IV)(μ-N)Ru(IV)(H(2)O)Cl(2)](2) (3) containing symmetric Ru(IV)-N-Ru(IV) bridges. The reaction of 1 with [Ru(II)(H)(Cl)(CO)(PCy(3))(2)] (Cy = cyclohexyl) gave the ruthenium(VI)-ruthenium(II) nitrido complex [L(OEt)Cl(2)Ru(VI)(μ-N)Ru(II)(H)Cl(CO)(PCy(3))(2)] (4). The observed short Ru(II)-N bond distance [1.915(5) Å] and high C-O stretching frequency (1985 cm(-1)) in 4 are suggestive of π interaction between Ru(II) and the nitride.
- Published
- 2012
- Full Text
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