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Summers BS, Thomas Broome S, Pang TWR, Mundell HD, Koh Belic N, Tom NC, Ng ML, Yap M, Sen MK, Sedaghat S, Weible MW, Castorina A, Lim CK, Lovelace MD, Brew BJ. A Review of the Evidence for Tryptophan and the Kynurenine Pathway as a Regulator of Stem Cell Niches in Health and Disease. Int J Tryptophan Res 2024; 17:11786469241248287. [PMID: 38757094 PMCID: PMC11097742 DOI: 10.1177/11786469241248287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 04/03/2024] [Indexed: 05/18/2024] Open
Abstract
Stem cells are ubiquitously found in various tissues and organs in the body, and underpin the body's ability to repair itself following injury or disease initiation, though repair can sometimes be compromised. Understanding how stem cells are produced, and functional signaling systems between different niches is critical to understanding the potential use of stem cells in regenerative medicine. In this context, this review considers kynurenine pathway (KP) metabolism in multipotent adult progenitor cells, embryonic, haematopoietic, neural, cancer, cardiac and induced pluripotent stem cells, endothelial progenitor cells, and mesenchymal stromal cells. The KP is the major enzymatic pathway for sequentially catabolising the essential amino acid tryptophan (TRP), resulting in key metabolites including kynurenine, kynurenic acid, and quinolinic acid (QUIN). QUIN metabolism transitions into the adjoining de novo pathway for nicotinamide adenine dinucleotide (NAD) production, a critical cofactor in many fundamental cellular biochemical pathways. How stem cells uptake and utilise TRP varies between different species and stem cell types, because of their expression of transporters and responses to inflammatory cytokines. Several KP metabolites are physiologically active, with either beneficial or detrimental outcomes, and evidence of this is presented relating to several stem cell types, which is important as they may exert a significant impact on surrounding differentiated cells, particularly if they metabolise or secrete metabolites differently. Interferon-gamma (IFN-γ) in mesenchymal stromal cells, for instance, highly upregulates rate-limiting enzyme indoleamine-2,3-dioxygenase (IDO-1), initiating TRP depletion and production of metabolites including kynurenine/kynurenic acid, known agonists of the Aryl hydrocarbon receptor (AhR) transcription factor. AhR transcriptionally regulates an immunosuppressive phenotype, making them attractive for regenerative therapy. We also draw attention to important gaps in knowledge for future studies, which will underpin future application for stem cell-based cellular therapies or optimising drugs which can modulate the KP in innate stem cell populations, for disease treatment.
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Affiliation(s)
- Benjamin Sebastian Summers
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent’s Centre for Applied Medical Research, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, UNSW Sydney, NSW, Australia
| | - Sarah Thomas Broome
- Faculty of Science, Laboratory of Cellular and Molecular Neuroscience, School of Life Sciences, University of Technology Sydney, NSW, Australia
| | | | - Hamish D Mundell
- Faculty of Medicine and Health, New South Wales Brain Tissue Resource Centre, School of Medical Sciences, Charles Perkins Centre, University of Sydney, NSW, Australia
| | - Naomi Koh Belic
- School of Life Sciences, University of Technology, Sydney, NSW, Australia
| | - Nicole C Tom
- Formerly of the Department of Physiology, University of Sydney, NSW, Australia
| | - Mei Li Ng
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Maylin Yap
- Formerly of the Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Monokesh K Sen
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent’s Centre for Applied Medical Research, Sydney, NSW, Australia
- School of Medicine, Western Sydney University, NSW, Australia
- Faculty of Medicine and Health, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Sara Sedaghat
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Michael W Weible
- School of Environment and Science, Griffith University, Brisbane, QLD, Australia
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD, Australia
| | - Alessandro Castorina
- Faculty of Science, Laboratory of Cellular and Molecular Neuroscience, School of Life Sciences, University of Technology Sydney, NSW, Australia
| | - Chai K Lim
- Faculty of Medicine, Macquarie University, Sydney, NSW, Australia
| | - Michael D Lovelace
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent’s Centre for Applied Medical Research, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, UNSW Sydney, NSW, Australia
| | - Bruce J Brew
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent’s Centre for Applied Medical Research, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Clinical Medicine, UNSW Sydney, NSW, Australia
- Departments of Neurology and Immunology, St. Vincent’s Hospital, Sydney, NSW, Australia
- University of Notre Dame, Darlinghurst, Sydney, NSW, Australia
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Loch A, Tan KL, Danaee M, Idris I, Ng ML. Leucine-Rich Alpha-2-Glycoprotein: A Novel Predictor of Diastolic Dysfunction. Biomedicines 2023; 11:biomedicines11030944. [PMID: 36979923 PMCID: PMC10045934 DOI: 10.3390/biomedicines11030944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/12/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Leucine-rich α2-glycoprotein (LRG1) mediates cardiac fibrocyte activation. It is upregulated in inflammatory conditions, atherosclerosis, and fibrosis. Diastolic dysfunction (DD) is due to myocardial fibrosis. This cross-sectional study examined the relationship between LRG1 and DD. Patients with symptoms of chronic coronary ischemia were recruited. Patients with symptoms of overt heart failure, ejection fraction (EF) < 55%, impaired renal function, infection, and recent trauma were excluded from the study. Clinical parameters examined were SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX) score, echocardiographic assessment, and LRG1 levels. Binary stepwise logistic regression was used to evaluate the association between LRG1 and DD. Receiver Operating Characteristic (ROC) analysis was used to determine optimal cut-off values and predictive performance of LRG1. A total of 94 patients were enrolled in the study, with 47 having a clinical diagnosis of DD. Plasma LRG1 was significantly (U = 417.00, p < 0.001) higher in the DD group (M = 14) compared to the No-DD group (M = 8) by Mann-Whitney U test. There were higher SYNTAX scores in the DD group (M = 24.5) compared with No-DD (M = 7). LRG1 had significant predictability of DD (OR = 1.32 (95% CI: 1.14-1.53)). The ROC showed an AUC = 0.89 (95% CI: 0.82-0.95). LRG1 had a 78% sensitivity (95% CI: 65.3-87.7) and 72.3% specificity (95% CI: 57.4-84.4) for predicting DD at a cut-off value of "9". In conclusion, we identified LRG1 as a novel independent predictor of DD. Further studies are warranted to validate the utility of LRG1 in predicting DD.
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Affiliation(s)
- Alexander Loch
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Kok Leng Tan
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Kepala Batas 13200, Malaysia
| | - Mahmoud Danaee
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Iskandar Idris
- Division of Medical Sciences and Graduate Entry Medicine, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK
| | - Mei Li Ng
- Department of Medicine, National University of Singapore, Singapore 119228, Singapore
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Ng ML, Ang X, Yap KY, Ng JJ, Goh ECH, Khoo BBJ, Richards AM, Drum CL. Novel Oxidative Stress Biomarkers with Risk Prognosis Values in Heart Failure. Biomedicines 2023; 11:biomedicines11030917. [PMID: 36979896 PMCID: PMC10046491 DOI: 10.3390/biomedicines11030917] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/17/2023] [Accepted: 02/26/2023] [Indexed: 03/18/2023] Open
Abstract
Oxidative stress (OS) is mediated by reactive oxygen species (ROS), which in cardiovascular and other disease states, damage DNA, lipids, proteins, other cellular and extra-cellular components. OS is both initiated by, and triggers inflammation, cardiomyocyte apoptosis, matrix remodeling, myocardial fibrosis, and neurohumoral activation. These have been linked to the development of heart failure (HF). Circulating biomarkers generated by OS offer potential utility in patient management and therapeutic targeting. Novel OS-related biomarkers such as NADPH oxidases (sNox2-dp, Nrf2), advanced glycation end-products (AGE), and myeloperoxidase (MPO), are signaling molecules reflecting pathobiological changes in HF. This review aims to evaluate current OS-related biomarkers and their associations with clinical outcomes and to highlight those with greatest promise in diagnosis, risk stratification and therapeutic targeting in HF.
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Affiliation(s)
- Mei Li Ng
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Xu Ang
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Kwan Yi Yap
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Jun Jie Ng
- Vascular Surgery, Department of Cardiac, Thoracic and Vascular Surgery, National University Heart Centre, Singapore 119074, Singapore
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Eugene Chen Howe Goh
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Benjamin Bing Jie Khoo
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Arthur Mark Richards
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, Level 9, NUHCS, Singapore 119228, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore
| | - Chester Lee Drum
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, Level 9, NUHCS, Singapore 119228, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore
- Correspondence:
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Ng ML, Kuan WS, Pakkiri LS, Goh ECH, Wu LH, Drum CL. Deep phenotyping of oxidative stress in emergency room patients reveals homoarginine as a novel predictor of sepsis severity, length of hospital stay, and length of intensive care unit stay. Front Med (Lausanne) 2022; 9:1033083. [PMID: 36507541 PMCID: PMC9733670 DOI: 10.3389/fmed.2022.1033083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/10/2022] [Indexed: 11/27/2022] Open
Abstract
Background We aimed to determine primary markers of oxidative stress (OS) in ED patients which predict hospital length of stay (LoS), intensive care unit (ICU) LoS, and sepsis severity. Materials and methods This prospective, single center observational study was conducted in adult patients recruited from the ED who were diagnosed with either sepsis, infection without sepsis, or non-infectious, age-matched controls. 290 patients were admitted to the hospital and 24 patients had direct admission to the ICU. A panel of 269 OS and related metabolic markers were profiled for each cohort. Clinical outcomes were direct ICU admission, hospital LoS, ICU LoS, and post-hoc, adjudicated sepsis severity scoring. Bonferroni correction was used for pairwise comparisons. Principal component regression was used for dimensionality reduction and selection of plasma metabolites associated with sepsis. Multivariable negative binomial regression was applied to predict admission, hospital, and ICU LoS. Results Homoarginine (hArg) was the top discriminator of sepsis severity [sepsis vs. control: ROC-AUC = 0.86 (95% CI 0.81-0.91)], [sepsis vs. infection: ROC-AUC = 0.73 (95% CI 0.68-0.78)]. The 25th percentile of hArg [odds ratio (OR) = 8.57 (95% CI 1.05-70.06)] was associated with hospital LoS [IRR = 2.54 (95% CI 1.83-3.52)] and ICU LOS [IRR = 18.73 (95% CI 4.32-81.27)]. In prediction of outcomes, hArg had superior performance compared to arginine (Arg) [hArg ROC-AUC = 0.77 (95% CI 0.67-0.88) vs. Arg ROC-AUC = 0.66 (95% CI 0.55-0.78)], and dimethylarginines [SDMA ROC-AUC 0.68 (95% CI 0.55-0.79) and ADMA ROC-AUC = 0.68 (95% CI 0.56-0.79)]. Ratio of hArg and Arg/NO metabolic markers and creatinine clearance provided modest improvements in clinical prediction. Conclusion Homoarginine is associated with sepsis severity and predicts hospital and ICU LoS, making it a useful biomarker in guiding treatment decisions for ED patients.
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Affiliation(s)
- Mei Li Ng
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Win Sen Kuan
- Emergency Medicine Department, National University Hospital, National University Health System, Singapore, Singapore
| | | | - Eugene Chen Howe Goh
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Lik Hang Wu
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Chester Lee Drum
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore,Cardiovascular Research Institute, National University Health System, Singapore, Singapore,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore,*Correspondence: Chester Lee Drum,
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Akkaif MA, Ng ML, Sk Abdul Kader MA, Daud NAA, Sha'aban A, Ibrahim B. A review of the effects of ticagrelor on adenosine concentration and its clinical significance. Pharmacol Rep 2021; 73:1551-1564. [PMID: 34283374 DOI: 10.1007/s43440-021-00309-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 12/01/2022]
Abstract
BACKGROUND Ticagrelor is an oral antiplatelet drug that can reversibly bind to the platelet P2Y12 receptor. Ticagrelor is metabolized mainly by CYP3A4 and produces a rapid blood concentration-dependent platelet inhibitory effect. Unlike other P2Y12 receptor antagonists, many clinical features of ticagrelor are not related to P2Y12 receptor antagonism. PURPOSE This review aims to gather existing literature on the clinical effects of ticagrelor after inhibiting adenosine uptake. METHODOLOGY The current study reviewed literature related to the effects of ticagrelor on adenosine metabolism. The review also examined the drug's biological effects and clinical characteristics to see how it could be used in a clinical setting. RESULTS Many studies have shown that ticagrelor can inhibit equilibrative nucleoside transporter 1 (ENT1). This inhibition leads to intracellular adenosine uptake, increased adenosine half-life and plasma concentration levels and an enhanced adenosine-mediated biological effect. CONCLUSIONS Based on the studies reviewed, it was found that ticagrelor essentially inhibits adenosine absorption of adenosine into cells through ENT1, which increases the concentration in the blood and subsequently increases the protection of the heart muscle by adenosine. It also prevents platelet aggregation, and extends the biological effects of coronary arteries. Moreover, it leads to a lower mortality rate in acute coronary syndrome (ACS) patients.
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Affiliation(s)
- Mohammed Ahmed Akkaif
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800, Gelugor, Penang, Malaysia
| | - Mei Li Ng
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200, Gelugor, Penang, Malaysia
| | | | - Nur Aizati Athirah Daud
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800, Gelugor, Penang, Malaysia
| | - Abubakar Sha'aban
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800, Gelugor, Penang, Malaysia
| | - Baharudin Ibrahim
- Faculty of Pharmacy, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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Dear JW, Ng ML, Bateman DN, Leroy Sivappiragasam P, Choi H, Khoo BBJ, Ibrahim B, Drum CL. A metabolomic analysis of thiol response for standard and modified N-acetyl cysteine treatment regimens in patients with acetaminophen overdose. Clin Transl Sci 2021; 14:1476-1489. [PMID: 33742775 PMCID: PMC8301594 DOI: 10.1111/cts.13009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/07/2021] [Accepted: 01/11/2021] [Indexed: 12/20/2022] Open
Abstract
N-acetylcysteine (NAC) is an antidote to prevent acetaminophen (paracetamol-APAP)-induced acute liver injury (ALI). The 3-bag licensed 20.25 h standard regimen, and a 12 h modified regimen, are used to treat APAP overdose. This study evaluated the redox thiol response and APAP metabolites, in patients with a single APAP overdose treated with either the 20.25 h standard or 12 h modified regimen. We used liquid chromatography tandem mass spectrometry to quantify clinically important oxidative stress biomarkers and APAP metabolites in plasma samples from 45 patients who participated in a randomized controlled trial (SNAP trial). We investigated the time course response of plasma metabolites at predose, 12 h, and 20.25 h post-start of NAC infusion. The results showed that the 12 h modified regimen resulted in a significant elevation of plasma NAC and cysteine concentrations at 12 h post-infusion. We found no significant alteration in the metabolism of APAP, mitochondrial, amino acids, and other thiol biomarkers with the two regimens. We examined APAP and purine metabolism in overdose patients who developed ALI. We showed the major APAP-metabolites and xanthine were significantly higher in patients with ALI. These biomarkers correlated well with alanine aminotransferase activity at admission. Receiver operating characteristic analysis showed that at admission, plasma APAP-metabolites and xanthine concentrations were predictive for ALI. In conclusion, a significantly higher redox thiol response with the modified NAC regimen at 12 h postdose suggests this regimen may produce greater antioxidant efficacy. At baseline, plasma APAP and purine metabolites may be useful biomarkers for early prediction of APAP-induced ALI.
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Affiliation(s)
- James W Dear
- Pharmacology, Toxicology, and TherapeuticsCentre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
| | - Mei Li Ng
- Cardiovascular Research InstituteNational University Health SystemSingapore CitySingapore
- Department of MedicineYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
- Advanced Medical and Dental InstituteUniversiti Sains MalaysiaKepala BatasMalaysia
| | - D. Nicholas Bateman
- Pharmacology, Toxicology, and TherapeuticsCentre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
| | | | - Hyungwon Choi
- Cardiovascular Research InstituteNational University Health SystemSingapore CitySingapore
- Department of MedicineYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
- Institute of Molecular and Cell BiologyAgency for Science, Technology, and ResearchSingapore CitySingapore
| | - Benjamin Bing Jie Khoo
- Cardiovascular Research InstituteNational University Health SystemSingapore CitySingapore
- Department of MedicineYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
| | - Baharudin Ibrahim
- School of Pharmaceutical SciencesUniversiti Sains MalaysiaKepala BatasMalaysia
| | - Chester Lee Drum
- Cardiovascular Research InstituteNational University Health SystemSingapore CitySingapore
- Department of MedicineYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
- Department of SurgeryYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
- Department of BiochemistryYong Loo Lin School of MedicineNational University of SingaporeSingapore CitySingapore
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Akkaif MA, Daud NAA, Sha’aban A, Ng ML, Abdul Kader MAS, Noor DAM, Ibrahim B. The Role of Genetic Polymorphism and Other Factors on Clopidogrel Resistance (CR) in an Asian Population with Coronary Heart Disease (CHD). Molecules 2021; 26:molecules26071987. [PMID: 33915807 PMCID: PMC8036376 DOI: 10.3390/molecules26071987] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/06/2021] [Accepted: 03/19/2021] [Indexed: 12/14/2022] Open
Abstract
Clopidogrel is a widely-used antiplatelet drug. It is important for the treatment and prevention of coronary heart disease. Clopidogrel can effectively reduce platelet activity and therefore reduce stent thrombosis. However, some patients still have ischemic events despite taking the clopidogrel due to the alteration in clopidogrel metabolism attributable to various genetic and non-genetic factors. This review aims to summarise the mechanisms and causes of clopidogrel resistance (CR) and potential strategies to overcome it. This review summarised the possible effects of genetic polymorphism on CR among the Asian population, especially CYP2C19 *2 / *3 / *17, where the prevalence rate among Asians was 23.00%, 4.61%, 15.18%, respectively. The review also studied the effects of other factors and appropriate strategies used to overcome CR. Generally, CR among the Asian population was estimated at 17.2-81.6%. Therefore, our overview provides valuable insight into the causes of RC. In conclusion, understanding the prevalence of drug metabolism-related genetic polymorphism, especially CYP2C19 alleles, will enhance clinical understanding of racial differences in drug reactions, contributing to the development of personalised medicine in Asia.
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Affiliation(s)
- Mohammed Ahmed Akkaif
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; (M.A.A.); (N.A.A.D.); (A.S.); (D.A.M.N.)
| | - Nur Aizati Athirah Daud
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; (M.A.A.); (N.A.A.D.); (A.S.); (D.A.M.N.)
| | - Abubakar Sha’aban
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; (M.A.A.); (N.A.A.D.); (A.S.); (D.A.M.N.)
| | - Mei Li Ng
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang 13200, Malaysia;
| | | | - Dzul Azri Mohamed Noor
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; (M.A.A.); (N.A.A.D.); (A.S.); (D.A.M.N.)
| | - Baharudin Ibrahim
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia; (M.A.A.); (N.A.A.D.); (A.S.); (D.A.M.N.)
- Faculty of Pharmacy, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence: ; Tel.: +60-103664181
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Sukocheva OA, Furuya H, Ng ML, Friedemann M, Menschikowski M, Tarasov VV, Chubarev VN, Klochkov SG, Neganova ME, Mangoni AA, Aliev G, Bishayee A. Sphingosine kinase and sphingosine-1-phosphate receptor signaling pathway in inflammatory gastrointestinal disease and cancers: A novel therapeutic target. Pharmacol Ther 2020; 207:107464. [PMID: 31863815 DOI: 10.1016/j.pharmthera.2019.107464] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/10/2019] [Indexed: 02/07/2023]
Abstract
Inflammatory gastrointestinal (GI) diseases and malignancies are associated with growing morbidity and cancer-related mortality worldwide. GI tumor and inflammatory cells contain activated sphingolipid-metabolizing enzymes, including sphingosine kinase 1 (SphK1) and SphK2, that generate sphingosine-1-phosphate (S1P), a highly bioactive compound. Many inflammatory responses, including lymphocyte trafficking, are directed by circulatory S1P, present in high concentrations in both the plasma and the lymph of cancer patients. High fat and sugar diet, disbalanced intestinal flora, and obesity have recently been linked to activation of inflammation and SphK/S1P/S1P receptor (S1PR) signaling in various GI pathologies, including cancer. SphK1 overexpression and activation facilitate and enhance the development and progression of esophageal, gastric, and colon cancers. SphK/S1P axis, a mediator of inflammation in the tumor microenvironment, has recently been defined as a target for the treatment of GI disease states, including inflammatory bowel disease and colitis. Several SphK1 inhibitors and S1PR antagonists have been developed as novel anti-inflammatory and anticancer agents. In this review, we analyze the mechanisms of SphK/S1P signaling in GI tissues and critically appraise recent studies on the role of SphK/S1P/S1PR in inflammatory GI disorders and cancers. The potential role of SphK/S1PR inhibitors in the prevention and treatment of inflammation-mediated GI diseases, including GI cancer, is also evaluated.
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Affiliation(s)
- Olga A Sukocheva
- Discipline of Health Sciences, College of Nursing and Health Sciences, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Hideki Furuya
- Department of Surgery, Samuel Oschin Cancer Center Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Mei Li Ng
- Advanced Medical and Dental Institute, University Sains 13200 Kepala Batas, Pulau Pinang, Malaysia
| | - Markus Friedemann
- Institute of Clinical Chemistry and Laboratory Medicine, University Hospital `Carl Gustav Carus`, Technical University of Dresden, Dresden 01307, Germany
| | - Mario Menschikowski
- Institute of Clinical Chemistry and Laboratory Medicine, University Hospital `Carl Gustav Carus`, Technical University of Dresden, Dresden 01307, Germany
| | - Vadim V Tarasov
- Sechenov First Moscow State Medical University (Sechenov University), Moscow 119991, Russia
| | - Vladimir N Chubarev
- Sechenov First Moscow State Medical University (Sechenov University), Moscow 119991, Russia
| | - Sergey G Klochkov
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka 142432, Russia
| | - Margarita E Neganova
- Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka 142432, Russia
| | - Arduino A Mangoni
- Discipline of Clinical Pharmacology, College of Medicine and Public Health, Flinders University and Flinders Medical Centre, Bedford Park, South Australia 5042, Australia
| | - Gjumrakch Aliev
- Sechenov First Moscow State Medical University (Sechenov University), Moscow 119991, Russia; Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka 142432, Russia; GALLY International Research Institute, San Antonio, TX 78229, USA; Research Institute of Human Morphology, Moscow 117418, Russia
| | - Anupam Bishayee
- Lake Erie College of Osteopathic Medicine, Bradenton, FL 34211, USA.
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Abstract
Circular RNAs characterize a class of widespread and diverse endogenous RNAs which are non-coding RNAs that are made by back-splicing events and have covalently closed loops with no polyadenylated tails. Various indications specify that circular RNAs (circRNAs) are plentiful in the human transcriptome. However, their participation in biological processes remains mostly undescribed. To date thousands of circRNAs have been revealed in organisms ranging from Drosophila melanogaster to Homo sapiens. Functional studies specify that these transcripts control expression of protein-coding linear transcripts and thus encompass a key component of gene expression regulation. This chapter provide a comprehensive overview on functional validation of circRNAs. Furthermore, we discuss the recent modern methodologies for the functional validation of circRNAs such as RNA interference (RNAi) gene silencing assay, luciferase reporter assays, circRNA gain-of-function investigation via overexpression of circular transcript assay, RT-q-PCR quantification, and other latest applicable assays. The methods described in this chapter are demonstrated on the cellular model.
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Affiliation(s)
- Hisham Alkatib Huda
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Soundararajan Vijayarathna
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Chern Ein Oon
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Yeng Chen
- Faculty of Dentistry, Dental Research & Training Unit, and Oral Cancer Research and Coordinating Centre (OCRCC), University of Malaya, Kuala Lumpur, Malaysia
| | - Jagat R Kanwar
- Faculty of Health, Nanomedicine-Laboratory of Immunology and Molecular Biomedical Research (LIMBR), School of Medicine (SoM), Deakin University, Geelong, VIC, Australia
| | - Mei Li Ng
- Integrative Medicine Cluster, Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Sreenivasan Sasidharan
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia.
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10
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Ng ML, Yarla NS, Menschikowski M, Sukocheva OA. Regulatory role of sphingosine kinase and sphingosine-1-phosphate receptor signaling in progenitor/stem cells. World J Stem Cells 2018; 10:119-133. [PMID: 30310531 PMCID: PMC6177561 DOI: 10.4252/wjsc.v10.i9.119] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/27/2018] [Accepted: 08/05/2018] [Indexed: 02/06/2023] Open
Abstract
Balanced sphingolipid signaling is important for the maintenance of homeostasis. Sphingolipids were demonstrated to function as structural components, second messengers, and regulators of cell growth and survival in normal and disease-affected tissues. Particularly, sphingosine kinase 1 (SphK1) and its product sphingosine-1-phosphate (S1P) operate as mediators and facilitators of proliferation-linked signaling. Unlimited proliferation (self-renewal) within the regulated environment is a hallmark of progenitor/stem cells that was recently associated with the S1P signaling network in vasculature, nervous, muscular, and immune systems. S1P was shown to regulate progenitor-related characteristics in normal and cancer stem cells (CSCs) via G-protein coupled receptors S1Pn (n = 1 to 5). The SphK/S1P axis is crucially involved in the regulation of embryonic development of vasculature and the nervous system, hematopoietic stem cell migration, regeneration of skeletal muscle, and development of multiple sclerosis. The ratio of the S1P receptor expression, localization, and specific S1P receptor-activated downstream effectors influenced the rate of self-renewal and should be further explored as regeneration-related targets. Considering malignant transformation, it is essential to control the level of self-renewal capacity. Proliferation of the progenitor cell should be synchronized with differentiation to provide healthy lifelong function of blood, immune systems, and replacement of damaged or dead cells. The differentiation-related role of SphK/S1P remains poorly assessed. A few pioneering investigations explored pharmacological tools that target sphingolipid signaling and can potentially confine and direct self-renewal towards normal differentiation. Further investigation is required to test the role of the SphK/S1P axis in regulation of self-renewal and differentiation.
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Affiliation(s)
- Mei Li Ng
- Centenary Institute of Cancer Medicine and Cell Biology, Sydney NSW 2050, Australia
| | - Nagendra S Yarla
- Department of Biochemistry and Bioinformatics, Institute of Science, GITAM University, Rushikonda, Visakhapatnam 530 045, Andhra Pradesh, India
| | - Mario Menschikowski
- Institute of Clinical Chemistry and Laboratory Medicine, Carl Gustav Carus University Hospital, Technical University of Dresden, Dresden D-01307, Germany
| | - Olga A Sukocheva
- College of Nursing and Health Sciences, Flinders University of South Australia, Bedford Park SA 5042, Australia
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11
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Ng ML, Wong BY. Voice performance in tonal language speakers with glottal insufficiency due to unilateral vocal fold paralysis after injection laryngoplasty: a multidimensional study of Cantonese patients. Hong Kong Med J 2018; 24 Suppl 2:42-44. [PMID: 29938658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Affiliation(s)
- M L Ng
- Division of Speech and Hearing Sciences, Faculty of Education, The University of Hong Kong
| | - B Yh Wong
- Department of Ear, Nose and Throat, Queen Mary Hospital
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12
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LaRue J, Krejčí O, Yu L, Beye M, Ng ML, Öberg H, Xin H, Mercurio G, Moeller S, Turner JJ, Nordlund D, Coffee R, Minitti MP, Wurth W, Pettersson LGM, Öström H, Nilsson A, Abild-Pedersen F, Ogasawara H. Real-Time Elucidation of Catalytic Pathways in CO Hydrogenation on Ru. J Phys Chem Lett 2017; 8:3820-3825. [PMID: 28759996 DOI: 10.1021/acs.jpclett.7b01549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due to the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast time scales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time X-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.
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Affiliation(s)
- J LaRue
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
- Schmid College of Science and Technology, Chapman University , One University Drive, Orange, California 92866, United States
- Fritz-Haber Institute of the Max-Planck-Society , Faradayweg 4-6, D-14195 Berlin, Germany
| | - O Krejčí
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
- Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague , V Holešovičkách 2, 180 00, Prague, Czech Republic
- Institute of Physics of the Czech Academy of Sciences , Cukrovarnická 10, 162 53, Prague, Czech Republic
| | - L Yu
- SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University , Stanford, California 95305, United States
| | - M Beye
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M L Ng
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - H Öberg
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
| | - H Xin
- SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University , Stanford, California 95305, United States
| | - G Mercurio
- University of Hamburg and Center for Free Electron Laser Science , Luruper Chausse 149, D-22761 Hamburg, Germany
| | - S Moeller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - J J Turner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - D Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - R Coffee
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - M P Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - W Wurth
- University of Hamburg and Center for Free Electron Laser Science , Luruper Chausse 149, D-22761 Hamburg, Germany
- DESY Photon Science , Notkestrasse 85, 22607 Hamburg, Germany
| | - L G M Pettersson
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
| | - H Öström
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
| | - A Nilsson
- Department of Physics, AlbaNova University Center, Stockholm University , SE-10691 Stockholm, Sweden
| | - F Abild-Pedersen
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - H Ogasawara
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, California 94025, United States
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13
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Abstract
Sphingosine kinase (SphK) is an important signalling enzyme that catalyses the phosphorylation of sphingosine (Sph) to form sphingosine‑1‑phosphate (S1P). The multifunctional lipid, S1P binds to a family of five G protein-coupled receptors (GPCRs). As an intracellular second messenger, S1P activates key signalling cascades responsible for the maintenance of sphingolipid metabolism, and has been implicated in the progression of cancer, and the development of other inflammatory and metabolic diseases. SphK and S1P are critical molecules involved in the regulation of various cellular metabolic processes, such as cell proliferation, survival, apoptosis, adhesion and migration. There is strong evidence supporting the critical roles of SphK and S1P in the progression of diabetes mellitus, including insulin sensitivity and insulin secretion, pancreatic β‑cell apoptosis, and the development of diabetic inflammatory state. In this review, we summarise the current state of knowledge for SphK/S1P signalling effects, associated with the development of insulin resistance, pancreatic β‑cell death and the vascular complications of diabetes mellitus.
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Affiliation(s)
- Mei Li Ng
- Centenary Institute of Cancer Medicine and Cell Biology, Sydney, NSW 2050
- Sydney Medical School, Faculty of Medicine, University of Sydney, Sydney, NSW 2006, Australia
- Advanced Medical and Dental Institute, University Sains Malaysia, Kepala Batas, Penang 13200, Malaysia
- Correspondence to: Dr Mei Li Ng, Advanced Medical and Dental Institute, University Sains Malaysia, No. 1-8 (Lot 8), Persiaran Seksyen 4, 1, Bandar Putra Bertam, Kepala Batas, Penang 13200, Malaysia, E-mail:
| | - Carol Wadham
- Children's Cancer Institute Australia, Lowy Cancer Research Centre, University of New South Wales, Randwick, NSW 2031
| | - Olga A. Sukocheva
- School of Social Health Sciences, Flinders University, Bedford Park, SA 5042, Australia
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14
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Lovelace MD, Varney B, Sundaram G, Franco NF, Ng ML, Pai S, Lim CK, Guillemin GJ, Brew BJ. Current Evidence for a Role of the Kynurenine Pathway of Tryptophan Metabolism in Multiple Sclerosis. Front Immunol 2016; 7:246. [PMID: 27540379 PMCID: PMC4972824 DOI: 10.3389/fimmu.2016.00246] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 06/10/2016] [Indexed: 12/13/2022] Open
Abstract
The kynurenine pathway (KP) is the major metabolic pathway of the essential amino acid tryptophan (TRP). Stimulation by inflammatory molecules, such as interferon-γ (IFN-γ), is the trigger for induction of the KP, driving a complex cascade of production of both neuroprotective and neurotoxic metabolites, and in turn, regulation of the immune response and responses of brain cells to the KP metabolites. Consequently, substantial evidence has accumulated over the past couple of decades that dysregulation of the KP and the production of neurotoxic metabolites are associated with many neuroinflammatory and neurodegenerative diseases, including Parkinson’s disease, AIDS-related dementia, motor neurone disease, schizophrenia, Huntington’s disease, and brain cancers. In the past decade, evidence of the link between the KP and multiple sclerosis (MS) has rapidly grown and has implicated the KP in MS pathogenesis. KP enzymes, indoleamine 2,3-dioxygenase (IDO-1) and tryptophan dioxygenase (highest expression in hepatic cells), are the principal enzymes triggering activation of the KP to produce kynurenine from TRP. This is in preference to other routes such as serotonin and melatonin production. In neurological disease, degradation of the blood–brain barrier, even if transient, allows the entry of blood monocytes into the brain parenchyma. Similar to microglia and macrophages, these cells are highly responsive to IFN-γ, which upregulates the expression of enzymes, including IDO-1, producing neurotoxic KP metabolites such as quinolinic acid. These metabolites circulate systemically or are released locally in the brain and can contribute to the excitotoxic death of oligodendrocytes and neurons in neurological disease principally by virtue of their agonist activity at N-methyl-d-aspartic acid receptors. The latest evidence is presented and discussed. The enzymes that control the checkpoints in the KP represent an attractive therapeutic target, and consequently several KP inhibitors are currently in clinical trials for other neurological diseases, and hence may make suitable candidates for MS patients. Underpinning these drug discovery endeavors, in recent years, several advances have been made in how KP metabolites are assayed in various biological fluids, and tremendous advancements have been made in how specimens are imaged to determine disease progression and involvement of various cell types and molecules in MS.
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Affiliation(s)
- Michael D Lovelace
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, NSW, Australia; Faculty of Medicine, St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Bianca Varney
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research , Sydney, NSW , Australia
| | - Gayathri Sundaram
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research , Sydney, NSW , Australia
| | - Nunzio F Franco
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research , Sydney, NSW , Australia
| | - Mei Li Ng
- Faculty of Medicine, Sydney Medical School, University of Sydney , Sydney, NSW , Australia
| | - Saparna Pai
- Sydney Medical School, University of Sydney , Sydney, NSW , Australia
| | - Chai K Lim
- Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University , Sydney, NSW , Australia
| | - Gilles J Guillemin
- Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University , Sydney, NSW , Australia
| | - Bruce J Brew
- Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St Vincent's Centre for Applied Medical Research, Sydney, NSW, Australia; Faculty of Medicine, St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia; Department of Neurology, St Vincent's Hospital, Sydney, NSW, Australia
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15
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Abstract
Using x-ray photoelectron spectroscopy we observe the breaking of the strong interatomic bond in molecular CO at low temperature on a stepped Cu surface. Since the electronic structure of Cu does not allow for the splitting of CO at such low temperatures it suggests that there may be a less obvious pathway for the process. Through x-ray photoelectron spectroscopy we can clearly identify products associated with the dissociation of CO and the subsequent formation of stable graphitic carbon on the surface. However, the dissociation of CO can be inhibited when the stepped Cu surface is kept clean from surface carbon. These observations imply that the reaction is driven by the presence of small amounts of weakly bound carbon at the surface. Density-functional theory calculations confirm that carbon atoms on a stepped Cu surface indeed are the preferred adsorption sites for CO, which increases the stabilization of CO on the surface and weakens the C-O bond. This results in the breaking of the C-O bond at the step edge via the Boudouard reaction (2CO(ads)→C(ads)+CO(2)) with a barrier of 0.71 eV.
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Affiliation(s)
- M L Ng
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - F Abild-Pedersen
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - S Kaya
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Chemistry, Koç University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey
| | - F Mbuga
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - H Ogasawara
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - A Nilsson
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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16
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Xin H, LaRue J, Öberg H, Beye M, Dell'Angela M, Turner JJ, Gladh J, Ng ML, Sellberg JA, Kaya S, Mercurio G, Hieke F, Nordlund D, Schlotter WF, Dakovski GL, Minitti MP, Föhlisch A, Wolf M, Wurth W, Ogasawara H, Nørskov JK, Öström H, Pettersson LGM, Nilsson A, Abild-Pedersen F. Strong Influence of Coadsorbate Interaction on CO Desorption Dynamics on Ru(0001) Probed by Ultrafast X-Ray Spectroscopy and Ab Initio Simulations. Phys Rev Lett 2015; 114:156101. [PMID: 25933322 DOI: 10.1103/physrevlett.114.156101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Indexed: 06/04/2023]
Abstract
We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5σ and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process.
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Affiliation(s)
- H Xin
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 95305, USA
| | - J LaRue
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - H Öberg
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - M Beye
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - M Dell'Angela
- University of Hamburg and Center for Free Electron Laser Science, Luruper Chausse 149, D-22761 Hamburg, Germany
| | - J J Turner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - J Gladh
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - M L Ng
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - J A Sellberg
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - S Kaya
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - G Mercurio
- University of Hamburg and Center for Free Electron Laser Science, Luruper Chausse 149, D-22761 Hamburg, Germany
| | - F Hieke
- University of Hamburg and Center for Free Electron Laser Science, Luruper Chausse 149, D-22761 Hamburg, Germany
| | - D Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - W F Schlotter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - G L Dakovski
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - M P Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - A Föhlisch
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
- Fakultät für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - M Wolf
- Fritz-Haber Institute of the Max-Planck-Society, Faradayweg 4-6, D-14195 Berlin, Germany
| | - W Wurth
- University of Hamburg and Center for Free Electron Laser Science, Luruper Chausse 149, D-22761 Hamburg, Germany
- DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - H Ogasawara
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - J K Nørskov
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 95305, USA
| | - H Öström
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - L G M Pettersson
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
| | - A Nilsson
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
- Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - F Abild-Pedersen
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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Fan MS, Hong JH, Ng ML, Lee LK, Lui PK, Choy YH. Western Influences on Chinese Sexuality: Insights from a Comparison of the Sexual Behavior and Attitudes of Shanghai and Hong Kong Freshmen at Universities. ACTA ACUST UNITED AC 2015; 21:158-66. [PMID: 12291366 DOI: 10.1080/01614576.1995.11074148] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Chow CS, Hung LK, Chiu CP, Lai KL, Lam LN, Ng ML, Tam KC, Wong KC, Ho PC. IS SYMPTOMATOLOGY USEFUL IN DISTINGUISHING BETWEEN CARPAL TUNNEL SYNDROME AND CERVICAL SPONDYLOSIS? ACTA ACUST UNITED AC 2012; 10:1-5. [PMID: 16106494 DOI: 10.1142/s0218810405002425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Accepted: 01/25/2005] [Indexed: 11/18/2022]
Abstract
Hand paraesthesia is a common symptom found in patients either with carpal tunnel syndrome or cervical spondylosis. To differentiate between the two conditions, it is important to identify additional diagnostic symptoms. Ninety-two patients with operated carpal tunnel syndrome and 138 patients with spinal surgery for cervical spondylosis were reviewed. After exclusion of cases co-morbid with both cervical spondylosis and carpal tunnel syndrome or other neurological disorders, 44 patients with carpal tunnel syndrome and 41 patients with cervical spondylosis were compared. There were significant differences in the symptomatology between the two groups. In carpal tunnel syndrome, 84% had nocturnal paraesthesia, 82% hand paraesthesia were aggravated by hand activity, and hand pain occurred in 64%. The incidences were only 10%, 7% and 10%, respectively in cervical spondylosis. Neck pain was present in 76% of cervical spondylosis but only in 14% of carpal tunnel syndrome, and lower limb symptoms were present in 44% of cervical spondylosis and only 9% in carpal tunnel syndrome.
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Affiliation(s)
- C S Chow
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong S.A.R., China
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19
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Vinogradov NA, Zakharov AA, Ng ML, Mikkelsen A, Lundgren E, Mårtensson N, Preobrajenski AB. One-dimensional corrugation of the h-BN monolayer on Fe(110). Langmuir 2012; 28:1775-1781. [PMID: 22185488 DOI: 10.1021/la2035642] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on a new nanopatterned structure represented by a single atomic layer of hexagonal boron nitride (h-BN) forming long periodic waves on the Fe(110) surface. The growth process and the structure of this system are characterized by X-ray absorption (XAS), core-level photoemission spectroscopy (CL PES), low-energy electron microscopy (LEEM), microbeam low-energy electron diffraction (μLEED), and scanning tunneling microscopy (STM). The h-BN monolayer on Fe(110) is periodically corrugated in a wavy fashion with an astonishing degree of long-range order, periodicity of 2.6 nm, and the corrugation amplitude of ∼0.8 Å. The wavy pattern results from a strong chemical bonding between h-BN and Fe in combination with a lattice mismatch in either [111] or [111] direction of the Fe(110) surface. Two primary orientations of h-BN on Fe(110) can be observed corresponding to the possible directions of lattice match between h-BN and Fe(110), with approximately equal area of the boron nitride domains of each orientation.
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Affiliation(s)
- N A Vinogradov
- Department of Physics and Astronomy, Uppsala University, Box 530, 75121 Uppsala, Sweden
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20
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Gibson-Kueh S, Chee D, Chen J, Wang YH, Tay S, Leong LN, Ng ML, Jones JB, Nicholls PK, Ferguson HW. The pathology of 'scale drop syndrome' in Asian seabass, Lates calcarifer Bloch, a first description. J Fish Dis 2012; 35:19-27. [PMID: 22103767 DOI: 10.1111/j.1365-2761.2011.01319.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This is the first pathological description of 'scale drop syndrome' (SDS) in Asian seabass, Lates calcarifer Bloch. Cumulative mortality was estimated at 40-50%. The vasculitis in all major organs including the skin and associated tissue necrosis was distinctive. The dermis overlying scale beds was often necrotic and associated with scale loss. Necrosis of splenic ellipsoids, renal glomeruli and choroid rete glands of eye were further hallmarks of a disease with systemic vascular involvement. The brain was not spared vascular damage, and the resulting multifocal encephalomalacia probably accounts for the spiral swimming behaviour in some affected fish. Other lesions included accentuated hepatic lobulation and gastric gland necrosis. Nuclear chromatin margination and karyolysis in hepatocytes, renal tubular epithelium and gastric and intestinal epithelium suggest specific targeting of cells. Basophilic cytoplasmic inclusions were present in spleen, kidney, liver, heart and choroid rete, but they were not prominent. Using transmission electron microscopy, two morphological forms of virions were observed: single- and double-enveloped hexagonal virions. Based on size and morphology, these virions resemble iridovirus or herpesvirus. The cause of SDS is unknown, but the pathological changes, especially the vasculitis, suggest an infectious aetiology, possibly viral.
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Affiliation(s)
- S Gibson-Kueh
- School of Veterinary and Biomedical Sciences, Murdoch University, Western Australia, Australia.
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Preobrajenski AB, Ng ML, Vinogradov NA, Vinogradov AS, Lundgren E, Mikkelsen A, Mårtensson N. Impact of oxygen coadsorption on intercalation of cobalt under the h-BN nanomesh. Nano Lett 2009; 9:2780-2787. [PMID: 19492822 DOI: 10.1021/nl901316p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The process of penetration of cobalt atoms through the h-BN nanomesh on Rh(111) is investigated with both spectroscopic and microscopic techniques. It is discovered that oxygen coadsorption can drastically modify the physical properties and behavior of the deposited Co clusters upon postannealing. In the absence of oxygen, Co forms small nanoparticles in the pores (bonding parts) of the h-BN nanomesh, which start to agglomerate at elevated temperatures without any considerable intercalation. However, even a tiny amount of coadsorbed oxygen reduces cobalt agglomeration and greatly promotes its intercalation and trapping under h-BN. The oxygen exposure necessary for a complete intercalation of 1-2 monolayers of Co is very low, and the formation of oxidic species can be easily avoided. The nanomesh structure remains intact upon intercalating submonolayer amounts of Co, while further intercalation gradually distorts and finally destroys the periodic corrugation. Fortunately, this process is not accompanied by damaging the h-BN sheet itself, and the original structure can be restored by removing Co upon annealing at higher temperatures.
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Ong SP, Chu JJH, Ng ML. Inhibition of West Nile virus replication in cells stably transfected with vector-based shRNA expression system. Virus Res 2008; 135:292-7. [PMID: 18514349 DOI: 10.1016/j.virusres.2008.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 04/01/2008] [Accepted: 04/04/2008] [Indexed: 10/22/2022]
Abstract
In this study, the efficacies of short hairpin RNAs (shRNAs) targeting different regions of West Nile virus (WNV) strain Sarafend genome were investigated. Short hairpin RNAs targeting Capsid, NS2B and NS4B genes were cloned into pSilencer 3.1-H1 neo and designated as pshCapsid, pshNS2B and pshNS4B, respectively. Vero cells that were positively transfected were selected for creating stable cell lines expressing shRNAs constitutively. These cells were subjected to West Nile virus at multiplicity of infection (M.O.I.) of 10. The cells stably transfected with pshCapsid gave the best silencing effect among the three stable cell lines (transfected with pshCapsid, pshNS2B and pshNS4B) at both 12- and 24 h p.i. When compared to the non-transfected WNV-infected cells, pshCapsid stably transfected cells showed more than 4 log(10) unit reduction in viral transcripts and greater than 3 log(10) unit reduction in virus production. Cells stably transfected with pshNS2B did not exhibit as strong an inhibition when compared to the pshCapsid stably transfected cells having only 2 log(10) unit reduction in virus titre. The pshNS4B-stably transfected cells did not suppress WNV replication. Hence, from this study, pshCapsid has the potential to be developed into effective antiviral strategy for WNV infection.
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Affiliation(s)
- S P Ong
- Flavivirology Laboratory, Department of Microbiology, Yong Loo Lin School of Medicine, 5 Science Drive 2, National University of Singapore, 117597 Singapore, Singapore
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Yaiw KC, Hyatt A, Vandriel R, Crameri SG, Eaton B, Wong MH, Wang LF, Ng ML, Bingham J, Shamala D, Wong KT. Viral morphogenesis and morphological changes in human neuronal cells following Tioman and Menangle virus infection. Arch Virol 2008; 153:865-75. [PMID: 18330496 DOI: 10.1007/s00705-008-0059-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Accepted: 01/23/2008] [Indexed: 10/22/2022]
Abstract
Tioman virus (TioPV) and Menangle virus (MenPV) are two antigenically and genetically related paramyxoviruses (genus: Rubulavirus, family: Paramyxoviridae) isolated from Peninsular Malaysia (2001) and Australia (1997), respectively. Both viruses are potential zoonotic agents. In the present study, the infectivity, growth kinetics, morphology and morphogenesis of these two paramyxoviruses in a human neuronal cell (SK-N-SH) line were investigated. Sub-confluent SK-N-SH cells were infected with TioPV and MenPV at similar multiplicity of infection. These cells were examined by conventional and immunoelectron microscopy, and virus titres in the supernatants were assayed. Syncytia were observed for both infections in SK-N-SH cells and were more pronounced during the early stages of TioPV infection. The TioPV titre increased consistently (10(1)) every 12 h after infection. In MenPV-infected cells, cellular material was frequently observed within budding virions, and microfilaments and microtubules were abundant. Viral budding was common, and extracellular MenPVs tended to be more pleomorphic compared to TioPVs, which appeared to be more spherical in appearance. The MenPV cytoplasmic viral inclusion appeared to be comparatively smaller, loose and interspersed with randomly scattered circle-like particles, whereas huge tubule-like cytoplasmic inclusions were observed in TioPV-infected cells. Both viruses also displayed different cellular pathology in the SK-N-SH cells. The intracellular ultrastructural characteristics of these two viruses in infected neuronal cells may allow them to be differentiated by electron microscopy.
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Affiliation(s)
- K C Yaiw
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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Chin JFL, Chu JJH, Ng ML. The envelope glycoprotein domain III of dengue virus serotypes 1 and 2 inhibit virus entry. Microbes Infect 2006; 9:1-6. [PMID: 17196419 DOI: 10.1016/j.micinf.2006.09.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 09/25/2006] [Accepted: 09/30/2006] [Indexed: 11/23/2022]
Abstract
Dengue virus (DV) is a flavivirus and its urban transmission is maintained largely by its mosquito vectors and vertebrate host, often human. In this study, investigation was carried out on the involvement of domain III of the envelope (E) glycosylated protein of dengue virus serotypes 1 and 2 (DV-1 and DV-2 DIII) in binding to host cell surfaces, thus mediating virus entry. Domain III protein of flavivirus can also serve as an attractive target in inhibiting virus entry. The respective DV DIII proteins were expressed as soluble recombinant fusion proteins before purification through enzymatic cleavage and affinity purification. The purified recombinant DV-1 and DV-2 DIII proteins both demonstrated the ability to inhibit the entry of DV-1 and DV-2 into HepG2 cells and C6/36 mosquito cells. As such, the DV DIII protein is indeed important for the interaction with cellular receptors in both human and mosquito cells. In addition, this protein induced antibodies that completely neutralized homologous dengue serotypes although not with the same efficiency among the heterologous serotypes. This observation may be of importance when formulating a generic vaccine that is effective against all dengue virus serotypes.
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Affiliation(s)
- J F L Chin
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, Singapore 117597, Singapore
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25
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Ong SP, Choo BGH, Chu JJH, Ng ML. Expression of vector-based small interfering RNA against West Nile virus effectively inhibits virus replication. Antiviral Res 2006; 72:216-23. [PMID: 16870272 DOI: 10.1016/j.antiviral.2006.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 05/26/2006] [Accepted: 06/07/2006] [Indexed: 12/23/2022]
Abstract
RNA interference is one of the effective emerging anti-viral strategies to inhibit virus infection in cells. In this study, a small interfering RNA expressing vector (pSilencer-NS5) targeting the NS5 gene of West Nile virus (WNV) was employed to target and destroy WNV transcripts. Real-time PCR revealed drastic reduction in WNV RNA transcripts in pSilencer-NS5-transfected Vero cells. The virus infectious titre was also significantly reduced by 90% as determined by plaque assays. The resulting decrease in virus replication was shown to be specific since both scrambled and nucleotide(s) mismatch siRNA against WNV NS5 gene did not have any effect on WNV productive yields. Furthermore, Western immunoblot analysis on the expression of viral NS5 and envelope (E) proteins showed significant down-regulation on the expression of viral NS5 and envelope (E) proteins in virus-infected cells that were pre-transfected with pSilencer-NS5. These data clearly supported the notion that the expression of vector-based siRNA against WNV NS5 gene is able to exert its silencing effect on WNV-infected cells without inducing cytotoxicity, hence holding promise in therapeutic treatment of this important emerging infectious disease.
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Affiliation(s)
- S P Ong
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597 Singapore, Singapore
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Chu JJH, Leong PWH, Ng ML. Analysis of the endocytic pathway mediating the infectious entry of mosquito-borne flavivirus West Nile into Aedes albopictus mosquito (C6/36) cells. Virology 2006; 349:463-75. [PMID: 16490225 DOI: 10.1016/j.virol.2006.01.022] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 12/28/2005] [Accepted: 01/18/2006] [Indexed: 02/03/2023]
Abstract
The initial interaction between mosquito-borne flavivirus West Nile and mosquito cells is poorly characterized. This study analyzed the endocytic and the associated signaling pathway that mediate the infectious entry of West Nile virus (WNV) into mosquito cell line (C6/36). Pretreatment of C6/36 cells with pharmacological drugs that blocks clathrin-mediated endocytosis significantly inhibited virus entry. Furthermore, the transfection of functional blocking antibody against clathrin molecules and the overexpression of dominant-negative mutants of Eps15 in C6/36 cells caused a marked reduction in WNV internalization. WNV was shown to activate focal adhesion kinase (FAK) to facilitate the endocytosis of virus but not the mitogen-activated protein kinases (ERK1 and ERK2). Subsequent to the internalization of WNV, the virus particles are translocated along the endosomal pathway as revealed by double-immunofluorescence assays with anti-WNV envelope protein and cellular markers for early and late endosomes. Specific inhibitor for protein kinase C (PKC) was shown to be highly effective in blocking WNV entry by inhibiting endosomal sorting event. The disruption of the microtubule network using nocodazole also drastically affects the entry process of WNV but not the disruption of actin filaments by cytochalasin D. Finally, a low-pH-dependent step is required for WNV infection as revealed by the resistance of C6/36 cells to WNV infection in the presence of lysosomotropic agents.
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Affiliation(s)
- J J H Chu
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, Singapore 117597, Singapore
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Chu JJH, Leong PWH, Ng ML. Characterization of plasma membrane-associated proteins from Aedes albopictus mosquito (C6/36) cells that mediate West Nile virus binding and infection. Virology 2005; 339:249-60. [PMID: 15992848 DOI: 10.1016/j.virol.2005.05.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 04/25/2005] [Accepted: 05/20/2005] [Indexed: 11/20/2022]
Abstract
This study isolated and characterized the West Nile virus (WNV) putative receptor molecule(s) from Aedes albopictus mosquito (C6/36) cells. The binding of WNV to C6/36 cells was saturated with 5000 particles per cell. The entry of WNV into C6/36 cells was strongly inhibited when pretreated with proteinase K and to a lesser extent with sodium periodate. However, pretreatment of C6/36 cells with phospholipases, glycosidases, heparinases and neurimidase had no effect on virus entry. By using virus overlay protein blot assay, WNV was observed to bind to the 140-kDa, 95-kDa, 70-kDa and 55-kDa plasma membrane-associated molecules isolated from C6/36 cells. Murine antibodies generated against the 95-kDa and 70-kDa membrane proteins effectively blocked WNV, Japanese encephalitis virus (JEV) and Dengue virus (DV) serotype 2 infection in C6/36 cells. In addition, the binding of the recombinant-WNV envelope domain III protein to C6/36 cells can be inhibited by the anti-95-kDa and anti-70-kDa membrane protein antibodies. These data strongly supported the possibility that the 95-kDa and 70-kDa plasma membrane-associated proteins are part of a receptor complex for mosquito-borne flaviviruses (WNV, JEV and DV) on mosquito cells.
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Affiliation(s)
- J J H Chu
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597, Singapore
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Abstract
Scanning electron and atomic force microscopy was used for the first time to view the maturation of SARS-CoV at the cell surface. Scanning electron and atomic force microscopy was used for the first time to view the maturation of the severe acute respiratory syndrome–associated coronavirus at the cell surface. The surface form of the cells at advanced infection displayed prolific pseudopodia that, in addition to the rest of the plasma membrane, were also active sites of virus release. High magnification of the maturing virus particles showed a rosette appearance with short knoblike spikes under both the scanning electron and atomic force microscopes. The final expulsion step of the maturing virus particles seemed to result in some disruptions to the plasma membrane. The cytoskeletal network along the edge of the infected cells was enhanced and could be involved in transporting and expelling the progeny virus particles. Thickening of the actin filaments at the cell edge provided the bending force to extrude the virus particles.
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Affiliation(s)
- M L Ng
- Department of Microbiology, National University of Singapore, Singapore.
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Gibson-Kueh S, Ngoh-Lim GH, Netto P, Kurita J, Nakajima K, Ng ML. A systemic iridoviral disease in mullet, Mugil cephalus L., and tiger grouper, Epinephelus fuscoguttatus Forsskal: a first report and study. J Fish Dis 2004; 27:693-699. [PMID: 15575877 DOI: 10.1111/j.1365-2761.2004.00589.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A systemic iridoviral disease associated with high mortality was initially recognized in cultured mullet, Mugil cephalus L., and tiger grouper, Epinephelus fuscoguttatus Forsskal, by histopathology and transmission electron microscopy. Polymerase chain reaction was performed on tissues and viral isolates, using four published primer sets developed for the Red Sea bream iridovirus (RSIV). An indirect fluorescent antibody test was also performed on virus-infected ATCC gruntfin (GF) and seabass, Lates calcarifer Bloch, (SB) cells using a monoclonal antibody, RSIV M10. Our results suggested that the mullet and tiger grouper iridovirus bears genetic and antigenic similarities to RSIV.
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Affiliation(s)
- S Gibson-Kueh
- Aquatic Animal Health Branch, AgriFood and Veterinary Authority of Singapore, 6 Perahu Road, Singapore 718827.
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Abstract
The pathway of West Nile flavivirus early internalization events was mapped in detail in this study. Overexpression of dominant-negative mutants of Eps15 strongly inhibits West Nile virus (WNV) internalization, and pharmacological drugs that blocks clathrin also caused a marked reduction in virus entry but not caveola-dependent endocytosis inhibitory agent, filipin. Using immunocryoelectron microscopy, WNV particles were seen within clathrin-coated pits after 2 min postinfection. Double-labeling immunofluorescence assays and immunoelectron microscopy performed with anti-WNV envelope or capsid proteins and cellular markers (EEA1 and LAMP1) revealed the trafficking pathway of internalized virus particles from early endosomes to lysosomes and finally the uncoating of the virus particles. Disruption of host cell cytoskeleton (actin filaments and microtubules) with cytochalasin D and nocodazole showed significant reduction in virus infectivity. Actin filaments are shown to be essential during the initial penetration of the virus across the plasma membrane, whereas microtubules are involved in the trafficking of internalized virus from early endosomes to lysosomes for uncoating. Cells treated with lysosomotropic agents were largely resistant to infection, indicating that a low-pH-dependent step is required for WNV infection. In situ hybridization of DNA probes specific for viral RNA demonstrated the trafficking of uncoated viral RNA genomes to the endoplasmic reticulum.
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Affiliation(s)
- J J H Chu
- Flavivirology Laboratory, Department of Microbiology, 5 Science Dr. 2, National University of Singapore, Singapore 117597, Singapore
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Abstract
The mechanism of West Nile (WN) virus-induced cell death is determined by the initial infectious dose. In Vero cells infected with WN virus at an m.o.i. of 10 or greater, morphological changes characteristic of necrosis were observed as early as 8 h post-infection (p.i.). Pathological changes included extensive cell swelling and loss of plasma membrane integrity, as revealed by optical and electron microscopy. High extracellular lactate dehydrogenase (LDH) activity was observed together with leakage of the high mobility group 1 (HMGB1) protein into the extracellular space. When cells undergo necrosis, they release the HMGB1 protein, a pro-inflammatory mediator cytokine. At high infectious doses, loss of cell plasma membrane integrity was due to the profuse budding of WN progeny virus particles during maturation. When this profuse budding process was disrupted using cytochalasin B, LDH activity was reduced dramatically. In contrast, WN virus-induced cell killing occurred predominantly by apoptosis when cells were infected with an m.o.i. of </=1; the process of apoptosis observed was much later after infection (32 h p.i.). Fragmentation of DNA, chromatin condensation and formation of apoptotic bodies were all observed. This WN virus-induced apoptosis pathway was initiated by the release of cytochrome c from the mitochondria and was accompanied by the formation of apoptosomes. In turn, this led to the activation of caspase-9 and -3, and to the cleavage of the poly(ADP-ribose) polymerase.
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Affiliation(s)
- J J H Chu
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597 Singapore
| | - M L Ng
- Flavivirology Laboratory, Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597 Singapore
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Abstract
Background: Antipsychotics had been shown to cause erectile dysfunction (ED). This study aims to determine the rate and degree of ED in Chinese males who had chronic schizophrenia and were taking antipsychotic agents for at least four weeks in an outpatient psychiatric clinic in Hong Kong. Method: Seventy Chinese males with chronic schizophrenia attending the clinic were surveyed on the five aspects of erectile function using the International Index of Erectile Function Scale (IIEF-15). Their attitude on receiving treatment for any ED was also elicited using a standard attitude questionnaire. Results: Fifty-eight per cent of married subjects had an IIEF-15 score below the cut off point for normal erectile function, although married subjects had a higher mean score than the single or divorced subjects. There was no significant difference in total IIEF-15 score between subjects on different antipsychotics. The score also showed no significant correlation with the duration of medication. Most subjects preferred psychotherapy to sildenafil for treatment of their sexual dysfunction. Conclusion: The majority of Chinese males with schizophrenia and maintained on antipsychotic drugs in the outpatient clinic had sub-optimal erectile function. Psychological management was the treatment of choice for their dysfunction.
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Affiliation(s)
- M L Ng
- Department of Psychiatry, University of Hong Kong, China.
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Abstract
An isolate from a patient in the recent severe acute respiratory syndrome (SARS) outbreak in Singapore was used to infect Vero E6 cells. This study concentrated on the first 30 min of infection. It was discovered that the SARS coronavirus attached, entered, and uncoated the nucleocapsids, all within a 30-min period. At 5 min after infection, several virus particles lined the Vero cell plasma membrane. Virus particles were at various stages of fusion at the cell surface, since entry was not a synchronised process. After entry (10 and 15 min), spherical core particles moved into the cytoplasm within large vacuoles. Quite surprising at such early stages of infection (20 min), a virus-induced change in the infected cells was evident. The induction of myelin-like membrane whorls was obvious within the same vacuoles as the core particles. The significance of this virus-induced change is unknown at this stage. By 25-30 min postinfection (p.i.), the spherical core particles appeared to be disassociating and, in their place, doughnut-shaped electron-dense structures were observed. These could be the virus genomes together with the helical nucleocapsids. They were no longer in large vacuoles but packaged into smaller vacuoles in the cytoplasm, and occasionally in small groups.
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Affiliation(s)
- M L Ng
- Department of Microbiology, Faculty of Medicine, 5 Science Drive 2, National University of Singapore, Singapore 117597.
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Abstract
West Nile (Sarafend) virus has previously been shown to egress by budding at the plasma membrane of infected cells, but relatively little is known about the mechanism involved in this mode of release. During the course of this study, it was discovered that actin filaments take part in the virus maturation process. Using dual-labeled immunofluorescence and immunoelectron microscopy at late infection (10 hr p.i.), co-localization of viral structural (envelope and capsid) proteins with actin filaments was confirmed. The virus structural proteins were also immunoprecipitated with anti-actin antibody, further demonstrating the strong association between the two components. Perturbation of actin filaments by cytochalasin B strongly inhibited the release of West Nile virus (approximately 10,000-fold inhibition) when compared with the untreated cells. Infectious virus particles were recovered after the removal of cytochalasin B. Further confirmation was obtained when nucleocapsid particles were found associated with disrupted actin filaments at the periphery of cytochalasin B-treated cells. Together, these results showed that actin filaments do indeed have a key role in the release of West Nile (Sarafend) virions.
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Affiliation(s)
- J J H Chu
- Department of Microbiology, National University of Singapore, 5 Science Drive 2, Singapore 117597, Republic of Singapore
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Abstract
Iridoviruses have been associated with severe disease and economic loss in farmed food fish and ornamental fish, with mortality often reported to reach 50% or more. In the present study, three tropical marine food fish species and four tropical freshwater ornamental fish species with systemic iridovirus infections were examined histopathologically and ultrastructurally. Light microscopy consistently revealed pale to intensely basophilic hypertrophied virus-infected cells in spleen, kidney and intestine from all seven species. Ultrastructural examination showed changes in the vascular endothelium overlying hypertrophied virus-infected cells suggestive of pressure necrosis. Viral isolation was improved by the use of fibroblastic cell lines. This, together with the sub-endothelial location of infected cells in all infected species examined, suggests that systemic iridoviruses are mesotheliotropic.
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Affiliation(s)
- S Gibson-Kueh
- Aquatic Animal Health Branch, Animal and Plant Health Laboratory Division, AgriFood and Veterinary Authority of Singapore, 60 Sengkang East Way, Singapore 548596
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Abstract
This study attempts to isolate and characterize West Nile virus-binding molecules on the plasma membrane of Vero and murine neuroblastoma cells that is responsible for virus entry. Pretreatment of Vero cells with proteases, glycosidases (endoglycosidase H, alpha-mannosidase), and sodium periodate strongly inhibited West Nile virus infection, whereas treatments with phospholipases and heparinases had no effect. The virus overlay protein blot detected a 105-kDa molecule on the plasma membrane extract of Vero and murine neuroblastoma cells that bind to WN virus. Treatment of the 105-kDa molecules with beta-mercaptoethanol resulted in the virus binding to a series of lower molecular weight bands ranging from 30 to 40 kDa. The disruption of disulfide-linked subunits did not affect virus binding. N-linked sugars with mannose residues on the 105-kDa membrane proteins were found to be important in virus binding. Specific antibodies against the 105-kDa glycoprotein were highly effective in blocking virus entry. These results strongly supported the possibility that the 105-kDa protease-sensitive glycoprotein with complex N-linked sugars could be the putative receptor for WN virus.
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Affiliation(s)
- J J H Chu
- Department of Microbiology, 5 Science Drive 2, National University of Singapore, Singapore 117597, Singapore
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Chu JJH, Ng ML. Infection of polarized epithelial cells with flavivirus West Nile: polarized entry and egress of virus occur through the apical surface. J Gen Virol 2002; 83:2427-2435. [PMID: 12237424 DOI: 10.1099/0022-1317-83-10-2427] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Both polarized epithelial Vero (C1008) and non-polarized Vero (control) cells were grown on permeable cell culture inserts and infected either apically or basolaterally with West Nile (WN) or Kunjin (KUN) virus. KUN virus (closely related to WN virus) was used as a comparison. Using indirect immunofluorescence and plaque assays of productive virus titres, entry of WN and KUN viruses was confined to the apical surface of polarized epithelial cells. For the first time, these results provided evidence on the distribution of flavivirus-specific receptor(s) in polarized epithelial cells; that is to say that receptor expression was shown to be predominant at the apical surface. In addition, the release of these viruses from polarized Vero C1008 epithelial cells was also examined. Egress of WN virus strain Sarafend (S) was observed to occur predominantly at the apical surface of Vero C1008 cells. In contrast, the release of KUN virus was bi-directional from polarized Vero C1008 cells. Furthermore, disruption of the cellular microtubule network was shown to inhibit the apical release of WN (S) virus but had no effect on the release of KUN virus. Hence, the difference in the release of these closely related viruses suggested the involvement of a microtubule-dependent, polarized sorting mechanism for WN virus proteins but not for KUN virus proteins in polarized epithelial cells.
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Affiliation(s)
- J J H Chu
- Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597, Singapore1
| | - M L Ng
- Department of Microbiology, 5 Science Drive 2, National University of Singapore, 117597, Singapore1
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38
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Affiliation(s)
- M L Ng
- Department of Microbiology, 5 Science Drive 2, National University of Singapore, 11759 Singapore
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Chu JJH, Ng ML. Trafficking mechanism of West Nile (Sarafend) virus structural proteins. J Med Virol 2002; 67:127-36. [PMID: 11920827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Previous studies have shown that West Nile (Sarafend) virus matured by budding at the plasma membrane, which differs from the usual intracellular maturation of other flaviviruses. The present study investigated the trafficking mechanism of the envelope (E) and capsid (C) proteins of West Nile (Sarafend) virus during the replication cycle. The use of time-based double-immunofluorescence labelling coupled with the Triton X-100 extraction procedure revealed that both the E and C proteins were transported from the perinuclear region towards the plasma membrane along the microtubules simultaneously. The strong association of these virus proteins with the microtubules was demonstrated further with Triton X-100 extraction procedure coupled with double immunogold-labelling. Extraction of infected cells with Triton X-100 in high salt also revealed that virus E proteins were associated with the microtubules via protein-protein interaction. The disruption of microtubules with vinblastine sulphate inhibited the trafficking of both the virus E and C proteins. Both virus structural proteins were observed to co-localise and retained within vinblastine sulphate-induced microtubulin paracrystals. Extracellular virus production was also reduced drastically by vinblastine sulphate at non-cytotoxic concentration. Subsequent studies revealed that the transportation of virus E protein was associated with the microtubules-based motor protein, kinesin.
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Affiliation(s)
- J J H Chu
- Department of Microbiology, National University of Singapore, Singapore
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40
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Abstract
Mechanical stability, complete encapsulation, selective permeability, and suitable extra-cellular microenvironment, are the major considerations in designing microcapsules for cell encapsulation. We have developed four types of multi-layered microcapsules that allow selective optimization of these parameters. Primary hepatocytes were used as model cells to test these different microcapsule configurations. Type-1 microcapsules with an average diameter of 400 microm were formed by complexing modified collagen with a ter-polymer shell of 2-hydroxyethyl methylacrylate (HEMA), methacrylic acid (MAA) and methyl methacrylate (MMA), resulting in a capsule thickness of 2-5 microm. Cells in these microcapsules exhibited improved cellular functions over those cultured on collagen monolayers. Type-II microcapsules were formed by encapsulating the Type-I microcapsules in another 2-5 microm ter-polymer shell and a approximately 5 microm collagen layer between the two ter-polymer shells to ensure complete cell encapsulation. Type-II microcapsules comprised of a macro-porous exoskeleton with materials such as alumina sol-gel coated on the Type-I microcapsules. Nano-indendation assay indicated an improved mechanical stability over the Type-I microcapsules. Type-IV microcapsules were created by encapsulating Type-III microcapsules in another 2-5 microm ter-polymer shell, with the aim of imparting a negatively charged smooth surface to minimize plasma protein absorption and ensure complete cell encapsulation. The permeability for nutrient exchange, cellular functions in terms of urea production and mechanical stability of the microcapsules were characterized. The advantages and limitations of these microcapsules for tissue engineering are discussed.
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Affiliation(s)
- S M Chia
- Faculty of Medicine, National University of Singapore, Singapore
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Abstract
It has been difficult to detect and visualize the physical nucleocapsid particles during the replication process of the flaviviruses. The use of cryo-immunoelectron microscopy has clearly revealed the capsid proteins and nucleocapsid particles of West Nile (Sarafend) virus (a flavivirus) for the first time. Physical nucleocapsid particles accumulated in large numbers from 8 hr postinfection. Double immunolabeling of the envelope and capsid proteins showed a close association of these structural proteins for most of the replication cycle. By 10 hr postinfection, budding of nucelocapsids from the plasma membrane was very obvious. Although maturation at the plasma membrane was the dominant mode, during late infection, intracellular maturation into large vacuoles was also observed.
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Affiliation(s)
- M L Ng
- Department of Microbiology, National University of Singapore, Singapore.
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42
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Abstract
Two dengue 2-specific IgM monoclonal antibodies (MAb) recognised spatially unrelated epitopes on the envelope (E) protein of dengue 2 virus, which were also recognised by serum from 20 and 50%, respectively, of patients with a primary dengue 2 infection. Dengue 2 virus populations escaping neutralisation by MAb 6B2 (representing the majority population of dengue 2-specific IgM MAbs ) had a deduced amino acid change (G-S) in the pre-Membrane (prM) protein at position 15 and a second in the E protein at E311 (E-G). The change in the E protein was adjacent to the only other epitopes on dengue 2 virus (E307, E383-385) involved in neutralisation that have been identified but that were recognised by IgG antibodies. Dengue 2 virus escaping neutralisation by IgM MAb 10F2, representing the minority population of dengue 2-specific IgM MAbs, had the same deduced amino acid change (G-S) at prM15 as the 6B2 neutralisation escape mutant dengue 2 virus population and four deduced amino acid changes in the E protein (E69, T-I, in the glycosylation motif; E71, E-D; E112, S-G; E124, I-N), which may be close enough to each other to form a single epitope and a fifth at E402 (F-L) in a region of the E protein of TBE virus essential for the low pH-induced E protein dimer-trimer transition. The 10F2 neutralisation escape mutant, but not the 6B2 one, had lost its ability to cause fusion from within Aedes albopictus mosquito cells and was inactivated more rapidly than the 6B2 neutralisation escape mutant and wild type viruses at 42 degrees C. Dengue 2 viruses passaged in BHK cells in the absence of a selecting antibody, shared a common amino acid (S) at E53, which differed from both wild type and neutralisation escape mutant virus populations at this position (P) and may have been responsible for a significant reduction in the ability of these "passage control" virus populations to be neutralised by both 6B2 and 10F2 antibodies.
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Affiliation(s)
- S M Lok
- School of Life Sciences, Queensland University of Technology, Brisbane, Australia
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43
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Yau YH, Ho B, Tan NS, Ng ML, Ding JL. High therapeutic index of factor C Sushi peptides: potent antimicrobials against Pseudomonas aeruginosa. Antimicrob Agents Chemother 2001; 45:2820-5. [PMID: 11557475 PMCID: PMC90737 DOI: 10.1128/aac.45.10.2820-2825.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2001] [Accepted: 07/27/2001] [Indexed: 11/20/2022] Open
Abstract
Factor C protein isolated from the horseshoe crab, Carcinoscorpius rotundicauda, has endotoxin binding capability. Synthetic peptides of 34 amino acids based on the sequence of two regions of factor C (Sushi 1 and Sushi 3) as well as their corresponding mutants exhibited activities against 30 clinical isolates of Pseudomonas aeruginosa. Collectively, all four peptides demonstrated exceptionally effective bactericidal activity against P. aeruginosa with 90% minimal bactericidal concentrations (MBC(90)s) in the range of 0.06 to 0.25 microg/ml (16 to 63 nM). Viable bacteria were reduced by 90% after 7 min and were totally eradicated within 40 to 50 min. These peptides are minimally hemolytic against both rabbit and human erythrocytes even at concentrations up to 1,600-fold their MBC(90)s. Both in vitro and in vivo studies indicate that cytotoxic effects are small even at 1,000-fold their MBC(90)s. Furthermore, the Sushi peptides are tolerant of high-salt and adverse pH conditions. These findings demonstrate the promising therapeutic potential of the Sushi peptides.
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Affiliation(s)
- Y H Yau
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Singapore
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Ng ML, Gilbert HR, Lerman JW. Fundamental frequency, intensity, and vowel duration characteristics related to perception of Cantonese alaryngeal speech. Folia Phoniatr Logop 2001; 53:36-47. [PMID: 11125259 DOI: 10.1159/000052652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Fundamental frequency (F(0)), F(0) contours, vowel duration, and intensity associated with Cantonese alaryngeal speech, and their relation to the perception of meaning were studied. Thirty adult male native Cantonese speakers participated in the study: 10 esophageal, 10 electrolaryngeal, and 10 laryngeal speakers. Results indicated that perceptually, listeners were able to identify what the Cantonese esophageal speakers were saying, particularly for words associated with high-level, low-falling and high-rising tonal contours. Acoustic analysis of the speech signals of the esophageal speakers indicated that intensity and durational data did not contribute to the perception of meaning. The F(0) contours appeared to be the acoustic cues associated with the signal that contributed most to the perception of meaning.
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Affiliation(s)
- M L Ng
- Department of Speech Pathology and Audiology, Illinois State University, Normal, IL 16790-4720, USA.
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45
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Ng LC, Teng LC, Ng ML, Sazali BS, Khalid BA. Microalbuminuria measurements by two in-house ELISA methods. Malays J Pathol 2000; 22:73-8. [PMID: 16329538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Detection of microalbuminuria is important in the management of diabetic patients since it is predictive of development of proteinuria and nephropathy. Two sensitive and specific in-house ELISAs for microalbuminuria were established and validated. One of the ELISAs was based on antigen coating while the other employed antibody coating. Recovery and linearity experiments gave acceptable results of 100 +/- 10%, while precision results were <10% for intra-assay and <12% for inter-assay coefficients of variation (CVs). The standard curve ranged from 10-625 ug/l, equivalent to 0.2-12.5 mg/l for urine samples diluted 1:20 fold. When the antibody coated ELISA was compared to antigen coated ELISA, a correlation of r=0.996 was obtained. When compared to commercial kits, the in-house ELISAs gave good correlations of r=0.961 versus the Boehringer Mannheim Micral Test strips and r=0.940 versus Ames Microalb Turbidimetry. The normal microalbumin reference ranges determined for 12h, first morning and random urine samples were 0.7-5.3 mg, 0.1-10.2 mg/l and 0.8-26.1 mg/l respectively. The normal albumin excretion rate (AER) was 1.0-7.3 ug/min while untimed urine samples gave results of 0.1-0.9 and 0.2-1.6 mg/mmol after dividing by creatinine concentrations. The ELISAs were used to detect microalbuminuria in 338 random urine samples from diabetic patients. A high percentage 47.9% was found to be positive for microalbuminuria and 18.0% had macroalbuminuria >25 mg/mmol. Thus screening for microalbuminuria together with creatinine measurements using random urine samples can be used for management of diabetic patients.
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Affiliation(s)
- L C Ng
- Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur
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Ng ML, Lerman JW, Gilbert HR. Perceptions of tonal changes in normal laryngeal, esophageal, and artificial laryngeal male Cantonese speakers. Folia Phoniatr Logop 2000; 50:64-70. [PMID: 9624857 DOI: 10.1159/000021451] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Listeners were asked to identify six tonal variations in the production of the syllables /ji/ and /si/ produced by 10 normal laryngeal (NL), 10 standard esophageal (SE), and 10 Servox-type electrolarynx (EL) Cantonese speakers. The purpose of the present study was to determine if alaryngeal Cantonese speakers could differentiate meanings associated with different tone levels. Results indicated that listeners' identification of the six tones for each syllable produced by the SE speakers was similar in pattern to those produced by the NL speakers of Cantonese. For both NL and SE speech, the high-level, low-falling, and high-rising tones were perceived more accurately than the mid-level, low-level, and low-rising tones. Identification of the six tones for each syllable as produced by the EL speakers was significantly poorer due to the limitations of the electrolarynx.
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Affiliation(s)
- M L Ng
- Department of Speech Pathology and Audiology, Illinois State University, Normal 61790-4720, USA.
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Ng ML, Warlow RS, Chrishanthan N, Ellis C, Walls RS. Preliminary criteria for the definition of allergic rhinitis: a systematic evaluation of clinical parameters in a disease cohort (II). Clin Exp Allergy 2000; 30:1417-22. [PMID: 10998018 DOI: 10.1046/j.1365-2222.2000.00913.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND This study is a development of the work done in 'Preliminary criteria for the definition of allergic rhinitis: a systematic evaluation of clinical parameters in a disease cohort (I)'. OBJECTIVE We sought to develop criteria which could be routinely used to define allergic rhinitis. METHODS A total of 47 allergic rhinitis and 23 normal subjects were evaluated with a detailed questionnaire and history, physical examination, serum total immunoglobulin (Ig) E, skin prick tests and serum EAST's. RESULTS Based on this data, we developed a preliminary scoring system by which a reliable diagnosis of allergic rhinitis can be made, which is based on the prevalence adjusted strength of association delta ( partial differential) rank values described in this report. Cumulative frequency histograms were constructed for allergic rhinitis and normal subjects in a variety of configurations. CONCLUSION A simple scoring system which can be used to diagnose allergic rhinitis on a routine basis was developed in this study.
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Affiliation(s)
- M L Ng
- Immunology Department, Concord Repatriation Hospital, Concord, Sydney, NSW 2139, Australia
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48
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Tan NS, Ng ML, Yau YH, Chong PK, Ho B, Ding JL. Definition of endotoxin binding sites in horseshoe crab factor C recombinant sushi proteins and neutralization of endotoxin by sushi peptides. FASEB J 2000; 14:1801-13. [PMID: 10973930 DOI: 10.1096/fj.99-0866com] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Three truncated fragments, harboring different sushi domains, namely, sushi123, sushi1, and sushi3 domains, of Factor C were produced as biologically active secreted recombinant proteins. Sushi1 and 3 each has a high-affinity LPS binding site with K:(d) of 10(-9) to 10(-10) M. Positive cooperativity in sushi123 resulted in a 1000-fold increase in K:(d)2. The core LPS binding region of sushi1 and 3 reside in two 34-mer peptides, S1 and S3. A rigidly held disulfide-bonded structure is not essential but is important for LPS binding, as confirmed by a 100- to 10000-fold decrease in affinity. Both S1 and S3 can inhibit LAL reaction and LPS-induced hTNF-alpha secretion with different potency. LAL assay revealed that at least two molecules of S1 bind cooperatively to one LPS molecule, with Hill's coefficient of 2.42. The LPS binding by S3 is independent and noncooperative. The modified SDelta1 and SDelta3 peptides exhibited increased LPS neutralization potential although its LPS binding affinities indicated only a 10-fold improvement. Hence, the structural difference of the four sushi peptides conferred different efficiencies in LPS neutralization without altering their binding affinity for LPS. Circular dichroism spectrometry revealed that the four peptides underwent conformational change in the presence of lipid A, transitioning from a random coil to either an alpha-helical or beta-sheet structure. Two factors are critical for the sensitivity of Factor C to LPS: 1) the presence of multiple binding sites for LPS on a single Factor C molecule; and 2) high positive cooperativity in LPS binding. The results showed that in the design of an improved LPS binding and neutralizing peptide, charge balance of the peptide is a critical parameter in addition to its structure.
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Affiliation(s)
- N S Tan
- Department of Biological Sciences, Department of Microbiology, National University of Singapore, Singapore 117543
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49
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Ng ML, Warlow RS, Chrishanthan N, Ellis C, Walls R. Preliminary criteria for the definition of allergic rhinitis: a systematic evaluation of clinical parameters in a disease cohort (I). Clin Exp Allergy 2000; 30:1314-31. [PMID: 10971479 DOI: 10.1046/j.1365-2222.2000.00853.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The aim of this study is to formulate criteria for the definition of allergic rhinitis. Other studies have sought to develop scoring systems to categorize the severity of allergic rhinitis symptoms but it was never used for the formulation of diagnostic criteria. These other scoring systems were arbitrarily chosen and were not derived by any statistical analysis. To date, a study of this kind has not been performed. OBJECTIVE The hypothesis of this study is that it is possible to formulate criteria for the definition of allergic rhinitis. This is the first study to systematically examine and evaluate the relative importance of symptoms, signs and investigative tests in allergic rhinitis. We sought to statistically rank, from the most to the least important, the multiplicity of symptoms, signs and test results. METHODS Forty-seven allergic rhinitis and 23 normal subjects were evaluated with a detailed questionnaire and history, physical examination, serum total immunoglobulin E, skin prick tests and serum enzyme allergosorbent tests (EAST). RESULTS Statistical ranking of variables indicated rhinitis symptoms (nasal, ocular and oronasal) were the most commonly occurring, followed by a history of allergen provocation, then serum total IgE, positive skin prick tests and positive EAST's to house dust mite, perennial rye and bermuda/couch grass. Throat symptoms ranked even lower whilst EAST's to cat epithelia, plantain and cockroach were the least important. Not all symptoms, signs and tests evaluated proved to be statistically significant when compared to a control group; this included symtoms and signs which had been considered historically to be traditionally associated with allergic rhinitis, e.g. sore throat and bleeding nose. CONCLUSION In performing statistical analyses, we were able to rank from most to least important, the multiplicity of symptoms signs and test results. The most important symptoms and signs were identified for the first time, even though some of these were not included in our original selection criteria for defining the disease cohort i.e. sniffing, postnasal drip, oedematous nasal mucosa, impaired sense of smell, mouth breathing, itchy nose and many of the specific provocation factors.
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Affiliation(s)
- M L Ng
- Immunology Department, Concord Repatriation Hospital, Concord, Australia
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50
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Abstract
Entry processes were compared between dengue-2 (DEN-2) virus and a DEN-2 neutralisation escape mutant virus in baby hamster kidney (BHK) cells. The mutant virus (mu6B2) was resistant to neutralisation by a monoclonal antibody, MAb 6B2. Infection of BHK cells by the wild-type DEN-2 virus resulted in direct penetration of the virions into the cytoplasm whereas the mutant virus entered cells by endocytosis. The continual presence of the monoclonal antibody might have asserted some pressure for the mutant to adopt a different mode of entry.
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Affiliation(s)
- H Y Lim
- Department of Microbiology, National University of Singapore, Singapore
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