39 results on '"Yong SK"'
Search Results
2. Life Cycle Costs & Housing Affordability Measurement
- Author
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Ling, FPP, Yong, SK, Smith, PV, Ling, FPP, Yong, SK, and Smith, PV
- Abstract
This paper examines current problems with home ownership affordability measurement and presents an innovative affordability measurement model that incorporates a comprehensive assessment and risk analysis of housing life cycle costs. The main method used to measure home ownership affordability is the benchmark ratio method whereby housing costs should not exceed a benchmark proportion of household income. the approach typically focuses on mortgage costs with other acquisition and operational costs largely ignored or given scant consideration. There is also a lack of data, impartial advice and financial tools available for home purchasers to effectively undertake a comprehensive analysis and risk assessment of affordability based on total potential costs. Purchasers largely rely on advice provided by entities with a vested interest in the process (such as financial institutions). Deregulation of financial sectors, high levels of competition amongst housing finance providers and a low inflationary environment over the last decade have combined to significantly increase the borrowing capacity of home purchasers in many countries around the world. This has fuelled a dramatic rise in the levels of household debt in countries like Australia who now has one of the highest personal debt-to-income ratios in the world. Questions are now being raised about the lending practices of housing finance providers particularly in the light of the US sub-prime mortgage market collapse in recent years. the model helps to address these problems by providing an independent and comprehensive financial analysis of home ownership costs and the affordability of these costs for a purchaser's specific circumstances. It focuses on creating greater consumer awareness of the total costs of ownership and concomitant financial risks.
- Published
- 2010
3. Type of Preexisting Lipid Therapy Predicts LDL-C Response to Ezetimibe
- Author
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Meyers, Charles D, primary, Moon, Yong SK, additional, Ghanem, Hoda, additional, and Wong, Nathan D, additional
- Published
- 2006
- Full Text
- View/download PDF
4. Niacin extended-release/ lovastatin: combination therapy for lipid disorders
- Author
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Moon, Yong SK, primary and Kashyap, Moti L, additional
- Published
- 2002
- Full Text
- View/download PDF
5. Electroreflectance and photoluminescence study of InN.
- Author
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Jung-Won JY Yoon, Sung SSK Kim, Hyeonsik HC Cheong, Hui-Chan HS Seo, Soon-Yong SK Kwon, Hee HJK Kim, Yoori YS Shin, Euijoon EY Yoon, and Yoon-Soo YP Park
- Subjects
PHOTOLUMINESCENCE ,SPECTRAL reflectance ,METAL organic chemical vapor deposition ,INDIUM compounds - Abstract
Photoluminescence and electroreflectance (ER) measurements on InN thin films grown by metal-organic chemical vapour deposition were performed at ambient and low temperatures. Franz-Keldysh oscillations (FKO's) were observed in the ER spectra. From the analysis of the FKO's, the bandgap of an as-deposited film is estimated to be 0.66 ± 0.02 eV at 90 K, whereas the low-temperature (8 K) photoluminescence (PL) appears as a broad peak between 0.67 eV and 0.77 eV. When the sample is annealed in air at temperatures below 420 °C, the bandgap energy at 90 K estimated from the FKO redshifts to 0.62 ± 0.02 eV. When the sample is annealed at temperatures of 420 °C or above, the low energy PL disappears, but the FKO signal persists with the same bandgap energy. We interpret that the crystalline quality of InN improves with annealing at lower temperatures but degrades dramatically with higher temperature annealing and conclude that the intrinsic bandgap energy of InN at 90 K is 0.62 ± 0.02 eV. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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6. Pharmacokinetics of mirodenafil, a new erectogenic, and its metabolite, SK3541, in rats: involvement of CYP1A1/2, 2B1/2, 2D subfamily, and 3A1/2 for the metabolism of both mirodenafil and SK3541
- Author
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This study was supported in part by a contract, “Pharmacokinetics of mirodenafil” from SK Chemicals, Seoul, South Korea., Choi, Young Hee; Seoul National University, Lee, Young Sun; Seoul National University, Lee, Myung Gull; Seoul National University, Kim, Tae Kon; SK Chemicals, Lee, Bong-Yong; SK Chemicals, This study was supported in part by a contract, “Pharmacokinetics of mirodenafil” from SK Chemicals, Seoul, South Korea., Choi, Young Hee; Seoul National University, Lee, Young Sun; Seoul National University, Lee, Myung Gull; Seoul National University, Kim, Tae Kon; SK Chemicals, and Lee, Bong-Yong; SK Chemicals
- Abstract
Purpose. This study was performed to find which types of hepatic CYP isoforms are responsible for the metabolism of mirodenafil (a new erectogenic) and one of its metabolite, SK3541, using various hepatic CYP inducers and inhibitors in rats. Methods. Mirodenafil at a dose of 20 mg/kg was administered intravenously to control rats and rats pretreated with various CYP inducers and inhibitors. The disappearance of SK3541 was also measured in vitro hepatic microsomes of rats with and without CYP inducer and inhibitors. Results. Compared to controls, in rats pretreated with 3-methylcholanthrene, orphenadrine, and dexamethasone (main inducers of CYP1A1/2, 2B1/2, and 3A1/2, respectively), the non-renal clearances (CLNRs) of mirodenafil were significantly faster (by 39.4%, 59.3%, and 63.9%, respectively). However, compared to controls, in rats pretreated with quinine and troleandomycin (main inhibitors of CYP2D subfamily and 3A1/2, respectively), the CLNRs of mirodenafil were significantly slower (by 36.1% and 33.2%, respectively). In rat hepatic microsomes spiked with furafylline, quinine, and troleandomycin (main inhibitors of CYP1A2, 2D subfamily, and 3A1/2, respectively), the intrinsic clearances (CLints) for the disappearance of SK3541 were significantly slower (by 18.4%, 35.3%, and 51.5%, respectively) than controls. Also in rat hepatic microsomes pretreated with orphenadrine (a main inducer of CYP2B1/2), the CLint for the disappearance of SK3541 was significantly faster (by 55.5%) than controls. Conclusions. The above data suggest that hepatic CYP1A1/2, 2B1/2, 2D subfamily, and 3A1/2 are involved in the metabolism of both mirodenafil and SK3541 in rats.
7. Sulfur-Containing Chitin and Chitosan Derivatives as Trace Metal Adsorbents: A Review
- Author
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Soon Kong Yong, Nanthi Bolan, William Skinner, Eric Guibal, Enzo Lombi, Yong, SK, Bolan, NS, Lombi, E, Skinner, W, and Guibal, E
- Subjects
Environmental Engineering ,chemistry.chemical_element ,macromolecular substances ,chitin ,Chitosan ,Metal ,chemistry.chemical_compound ,Chitin ,Organic chemistry ,crosslinking ,Epichlorohydrin ,Solubility ,Waste Management and Disposal ,wastewater remediation ,Water Science and Technology ,Chemistry ,technology, industry, and agriculture ,heavy metal ,Pollution ,Sulfur ,carbohydrates (lipids) ,sulfur ,visual_art ,visual_art.visual_art_medium ,Amine gas treating ,Glutaraldehyde ,chitosan - Abstract
Chitosan has low uptake for most heavy metals as well as high solubility in monoprotic acids. To address these problems, sulfur-containing functional groups have been introduced to enhance the sorption of heavy metals via formation of strong coordination bonds with heavy metals and also to improve its stability. The approaches to sulfur enrichment to the chitosan structure include grafting of sulfur-containing molecules to C2 amine or C6 hydroxyl groups. Crosslinking and grafting agents such as glutaraldehyde and epichlorohydrin have also been used in chitosan modification. In this review, special emphasis is placed on the synthesis pathways of sulfur-functionalization of chitin and chitosan and their metal uptakes. Generally, the uptake of soft acid metals such as Hg(II) and Cd(II) has been shown to increase with increasing sulfur content of modified chitosan. However, other factors such as the availability of thiol and amine groups as well as surface area of the modified chitosan also influence metal sorption. Refereed/Peer-reviewed
- Published
- 2013
- Full Text
- View/download PDF
8. Life Cycle Costs & Housing Affordability Measurement
- Author
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Smith, PV, Ling, FPP, and Yong, SK
- Abstract
This paper examines current problems with home ownership affordability measurement and presents an innovative affordability measurement model that incorporates a comprehensive assessment and risk analysis of housing life cycle costs. The main method used to measure home ownership affordability is the benchmark ratio method whereby housing costs should not exceed a benchmark proportion of household income. the approach typically focuses on mortgage costs with other acquisition and operational costs largely ignored or given scant consideration. There is also a lack of data, impartial advice and financial tools available for home purchasers to effectively undertake a comprehensive analysis and risk assessment of affordability based on total potential costs. Purchasers largely rely on advice provided by entities with a vested interest in the process (such as financial institutions). Deregulation of financial sectors, high levels of competition amongst housing finance providers and a low inflationary environment over the last decade have combined to significantly increase the borrowing capacity of home purchasers in many countries around the world. This has fuelled a dramatic rise in the levels of household debt in countries like Australia who now has one of the highest personal debt-to-income ratios in the world. Questions are now being raised about the lending practices of housing finance providers particularly in the light of the US sub-prime mortgage market collapse in recent years. the model helps to address these problems by providing an independent and comprehensive financial analysis of home ownership costs and the affordability of these costs for a purchaser's specific circumstances. It focuses on creating greater consumer awareness of the total costs of ownership and concomitant financial risks.
- Published
- 2010
9. Development of a chitosan/nanosilica biocomposite with arene functionalization via hydrothermal synthesis for acid red 88 dye removal.
- Author
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Wu R, Abdulhameed AS, Jawad AH, Yong SK, Li H, ALOthman ZA, Wilson LD, and Algburi S
- Subjects
- Silicon Dioxide, Adsorption, Kinetics, Hydrogen-Ion Concentration, Chitosan, Water Pollutants, Chemical
- Abstract
Herein, the polymer nanomatrix of chitosan/SiO
2 (CHI/n-SiO2 ) was enriched with a π-π electron donor-acceptor system using diaromatic rings of benzil (BEZ) assisted via a hydrothermal process to obtain an effective adsorbent of chitosan-benzil/SiO2 (CHI-BEZ/n-SiO2 ). The polymer nanomatrix (CHI/n-SiO2 ) and the resulting adsorbent (CHI-BEZ/n-SiO2 ) were applied to remove the anionic acid red 88 (AR88) dye from aqueous media in a comparative mode. Box-Behnken design (BBD) was adopted to optimize AR88 adsorption onto CHI/n-SiO2 and CHI-BEZ/n-SiO2 with respect to variables that influence AR88 adsorption (adsorbent dose: 0.02-0.1 g/100 mL; pH: 4-10; and time: 10-90). The adsorption studies at equilibrium were conducted with a variety of initial AR88 dye concentrations (20-200 mg/L). The adsorption isotherm results reveal that the AR88 adsorption by CHI/n-SiO2 and CHI-BEZ/n-SiO2 are described by the Langmuir model. The kinetic adsorption profiles of AR88 with CHI/n-SiO2 and CHI-BEZ/n-SiO2 reveal that the pseudo-first-order model provides the best fit results. Interestingly, CHI-BEZ/n-SiO2 has a high adsorption capacity (261.2 mg/g), which exceeds the adsorption capacity of CHI/n-SiO2 (215.1 mg/g) that relates to the surface effects of SiO2 and the functionalization of chitosan with BEZ. These findings show that CHI-BEZ/n-SiO2 represents a highly efficient adsorbent for the removal of harmful pollutants from water, which outperforming the CHI/n-SiO2 system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
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10. Review of Semiconductor Flash Memory Devices for Material and Process Issues.
- Author
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Kim SS, Yong SK, Kim W, Kang S, Park HW, Yoon KJ, Sheen DS, Lee S, and Hwang CS
- Abstract
Vertically integrated NAND (V-NAND) flash memory is the main data storage in modern handheld electronic devices, widening its share even in the data centers where installation and operation costs are critical. While the conventional scaling rule has been applied down to the design rule of ≈15 nm (year 2013), the current method of increasing device density is stacking up layers. Currently, 176-layer-stacked V-NAND flash memory is available on the market. Nonetheless, increasing the layers invokes several challenges, such as film stress management and deep contact hole etching. Also, there should be an upper bound for the attainable stacking layers (400-500) due to the total allowable chip thickness, which will be reached within 6-7 years. This review summarizes the current status and critical challenges of charge-trap-based flash memory devices, with a focus on the material (floating-gate vs charge-trap-layer), array-level circuit architecture (NOR vs NAND), physical integration structure (2D vs 3D), and cell-level programming technique (single vs multiple levels). Current efforts to improve fabrication processes and device performances using new materials are also introduced. The review suggests directions for future storage devices based on the ionic mechanism, which may overcome the inherent problems of flash memory devices., (© 2022 Wiley-VCH GmbH.)
- Published
- 2023
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11. First observation of Afromorgus chinensis (boheman, 1858) (Coleoptera: Trogidae) on a rabbit (Oryctolagus cuniculus L., 1758) carcass and its implications in forensic entomology.
- Author
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Singh S, Yong SK, Rahimi R, Singh MKC, Low VL, Pittino R, and Heo CC
- Subjects
- Animals, Rabbits, Humans, Postmortem Changes, Forensic Sciences, Entomology, Cadaver, Feeding Behavior, Coleoptera, Forensic Entomology, Diptera
- Abstract
Beetles (Coleoptera) are known to constitute forensic evidence in medico-legal investigations as their presence can be used to date human remains in almost all decomposition stages. Many forensic studies focus on the successional colonization pattern of flies (Diptera); however, beetles have not so far been studied extensively for this aspect. A beetle of the genus Afromorgus Scholtz, 1986, A. chinensis (Boheman, 1858) (Scarabaeoidea: Trogidae), was found beneath a late decaying rabbit carcass at Paya Indah Wetland, Dengkil, Malaysia, for the first time. Both genus and species are already known to occur in Malaysia from literature.
- Published
- 2023
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12. Functionalization of chitosan biopolymer with SiO 2 nanoparticles and benzaldehyde via hydrothermal process for acid red 88 dye adsorption: Box-Behnken design optimization.
- Author
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Wu R, Abdulhameed AS, Yong SK, Li H, ALOthman ZA, Wilson LD, and Jawad AH
- Subjects
- Adsorption, Silicon Dioxide chemistry, Benzaldehydes, Coloring Agents, Kinetics, Hydrogen-Ion Concentration, Chitosan chemistry, Nanoparticles chemistry, Water Pollutants, Chemical chemistry
- Abstract
An effective hydrothermally prepared chitosan-benzaldehyde/SiO
2 adsorbent (CTA-BZA/SiO2 ) employed functionalization of a CTA biopolymer with SiO2 nanoparticles and BZA. CTA-BZA/SiO2 is an adsorbent that was utilized for the adsorption of an acidic dye (acid red 88, AR88) from synthetic wastewater. The fundamental adsorption variables (A: CTA-BZA/SiO2 dosage (0.02-0.1 g); B: pH (4-10); and C: duration (10-60)) were optimized via the Box-Behnken design (BBD). The Langmuir and Freundlich isotherms (coefficients of determination R2 = 0.99) agreed well with empirical data of AR88 adsorption by CTA-BZA/SiO2 . The pseudo-first-order model showed reasonable agreement with the kinetic data of AR88 adsorption by CTA-BZA/SiO2 . The maximal AR88 adsorption capacity (qmax ) for CTA-BZA/SiO2 was identified to be 252.4 mg/g. The electrostatic attractions between both the positively charged CTA-BZA/SiO2 adsorbent and the AR88 anions, plus the n-π, π-π, and H-bond interactions contribute to the favourable adsorption process. This study reveals that CTA-BZA/SiO2 has the capacity to be a suitable adsorbent for the removal of a wider range of organic dyes from industrial effluents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
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13. Silicon Nanowire Field-Effect Transistor as Label-Free Detection of Hepatitis B Virus Proteins with Opposite Net Charges.
- Author
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Yong SK, Shen SK, Chiang CW, Weng YY, Lu MP, and Yang YS
- Subjects
- Carcinoma, Hepatocellular, Delivery of Health Care, Hepatitis B virus, Humans, Liver Neoplasms, Silicon, Hepatitis B diagnosis, Hepatitis B Surface Antigens analysis, Nanowires, Trans-Activators analysis, Viral Regulatory and Accessory Proteins analysis
- Abstract
The prevalence of hepatitis B virus (HBV) is a global healthcare threat, particularly chronic hepatitis B (CHB) that might lead to hepatocellular carcinoma (HCC) should not be neglected. Although many types of HBV diagnosis detection methods are available, some technical challenges, such as the high cost or lack of practical feasibility, need to be overcome. In this study, the polycrystalline silicon nanowire field-effect transistors (pSiNWFETs) were fabricated through commercial process technology and then chemically functionalized for sensing hepatitis B virus surface antigen (HBsAg) and hepatitis B virus X protein (HBx) at the femto-molar level. These two proteins have been suggested to be related to the HCC development, while the former is also the hallmark for HBV diagnosis, and the latter is an RNA-binding protein. Interestingly, these two proteins carried opposite net charges, which could serve as complementary candidates for evaluating the charge-based sensing mechanism in the pSiNWFET. The measurements on the threshold voltage shifts of pSiNWFETs showed a consistent correspondence to the polarity of the charges on the proteins studied. We believe that this report can pave the way towards developing an approachable tool for biomedical applications.
- Published
- 2021
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14. Preliminary observation on the lepidopteran colonization on rat and rabbit carcasses in Malaysia.
- Author
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Singh S, Yong SK, Jalaludin NH, Brau E, Shamsudin NN, Keawbaingam N, and Heo CC
- Subjects
- Animals, Cadaver, Feeding Behavior, Larva, Malaysia, Rabbits, Rats, Forensic Entomology, Lepidoptera
- Abstract
The immature stages of necrophagous insects such as Diptera and Coleoptera play a vital ecological role in carrion decomposition. These invertebrates reduce the necromass significantly through consumption and recycle nutrients into organic forms which are readily being used by autotrophs or served as an abiotic storage in the soil ecosystem. Fly and beetle larvae are frequently encountered decomposers on ephemeral resource patches; however, lepidopterans associated with carrion decomposition is seldom reported. Here, we report colonization of Monopis sp. (Tineidae) and an unknown species of Psychidae on a rat carcass, and a Lithosiini caterpillar (Arctiidae) on a rabbit carcass in Peninsular Malaysia for the first time. The feeding behaviour and their potential forensic implications are discussed.
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- 2020
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15. Growth and metal uptake of spinach with application of co-compost of cat manure and spent coffee ground.
- Author
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Mohd Noor Keeflee SNK, Wan Mohd Zain WNA, Mohd Nor MN, Jamion NA, and Yong SK
- Abstract
Cat manure (CM) possesses high level of nutrients for growing food crop. However, animal manure may contain toxic elements that may contaminate food crop. Spent coffee ground (SCG) may be used to reduce mobility of heavy metals and reduce crop uptake. In this study, SCG was composted with CM for 31 days to produce a co-compost (SCG-CM) for growing spinach ( Spinacia oleracea ). The growth rate of spinach was assessed until its maturity, and the metal uptake of spinach shoot was determined thereafter using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The effect of soil treatment with SCG-CM on the height and elemental composition of spinach were compared with that of chicken manure compost (CMC). The prepared composts were primarily organic matter (72.9-81.4 % w/w) with the rest are ash (13.3-23.4 % w/w) and moisture (1.2-2.6 % w/w). Zinc content in SCG-CM (1261 ± 0.1 mg/kg) is significantly higher than that of soil and CMC (p < 0.05) and has exceeded the maximum permissible limit set by European Union Standard (2002) and the Malaysian Compost Quality Standard and Guidelines (2000). Matured spinach reached maximum plant height after 33 days. The amendment of SCG-CM significantly increased the height of spinach (32 ± 6 cm) compared to that of CMC (13 ± 1 cm) (p < 0.05). However, contents of Zn, Cu, Pb and Cd were not increased for spinach grown in the SCG-CM-amended soil, and the level of those elements are below permissible limit set by the Malaysian Food Act 1983 and Food Regulations 1985. This study shows that SCG-CM is effective in improving yield without causing accumulation of toxic trace elements in spinach., (© 2020 The Authors.)
- Published
- 2020
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16. Molecular Targets for the Testing of COVID-19.
- Author
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Yong SK, Su PC, and Yang YS
- Subjects
- COVID-19, COVID-19 Testing, Coronavirus Infections virology, Coronavirus Nucleocapsid Proteins, Humans, Nucleocapsid Proteins isolation & purification, Pandemics, Phosphoproteins, Pneumonia, Viral virology, RNA, Viral isolation & purification, SARS-CoV-2, Sensitivity and Specificity, Spike Glycoprotein, Coronavirus isolation & purification, Betacoronavirus isolation & purification, Clinical Laboratory Techniques methods, Coronavirus Infections diagnosis, Pneumonia, Viral diagnosis
- Abstract
The pandemic outbreaks of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), spread all over the world in a short period of time. Efficient identification of the infection by SARS-CoV-2 has been one of the most important tasks to facilitate all the following counter measurements in dealing with the infectious disease. In Taiwan, a COVID-19 Open Science Platform adheres to the spirit of open science: sharing sources, data, and methods to promote progress in academic research while corroborating findings from various disciplines has established in mid-February 2020, for collaborative research in support of the development of detection methods, therapeutics, and a vaccine for COVID-19. Research priorities include infection control, epidemiology, clinical characterization and management, detection methods (including viral RNA detection, viral antigen detection, and serum antibody detection), therapeutics (neutralizing antibody and small molecule drugs), vaccines, and SARS-CoV-2 pathogenesis. In addition, research on social ethics and the law are included to take full account of the impact of the COVID-19 virus., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2020
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17. Inclination towards research and the pursuit of a research career among medical students: an international cohort study.
- Author
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Ha TC, Ng S, Chen C, Yong SK, Koh GCH, Tan SB, Malhotra R, Altermatt F, Seim A, Biderman A, Woolley T, and Østbye T
- Subjects
- Adolescent, Adult, Female, Humans, Internationality, Male, Mentors, Professional Role, Prospective Studies, Research, Research Personnel psychology, Schools, Medical statistics & numerical data, Students, Medical statistics & numerical data, Surveys and Questionnaires, Young Adult, Biomedical Research, Career Choice, Research Personnel education, Students, Medical psychology
- Abstract
Background: Involvement of clinicians in biomedical research is imperative for the future of healthcare. Several factors influence clinicians' inclination towards research: the medical school experience, exposure to research article reading and writing, and knowledge of research. This cohort study follows up medical students at time of graduation to explore changes in their inclination towards research and pursuing a research career compared to their inclination at time of entry into medical school., Methods: Students from medical schools in six different countries were enrolled in their first year of school and followed-up upon graduation in their final year. Students answered the same self-administered questionnaire at both time points. Changes in inclination towards research and pursuing a research career were assessed. Factors correlated with these changes were analysed., Results: Of the 777 medical students who responded to the study questionnaire at entry into medical school, 332 (42.7%) completed the follow-up survey. Among these 332 students, there was no significant increase in inclination towards research or pursuing a research career over the course of their medical schooling. Students from a United States based school, in contrast to those from schools other countries, were more likely to report having research role models to guide them (51.5% vs. 0%-26.4%) and to have published in a peer-reviewed journal (75.7% vs. 8.9%-45%). Absence of a role model was significantly associated with a decrease in inclination towards research, while an increased desire to learn more about statistics was significantly associated with an increase in inclination towards pursuing a research career., Conclusion: Most medical students did not experience changes in their inclination towards research or pursuing a research career over the course of their medical schooling. Factors that increased their inclination to undertaking research or pursuing a research career were availability of a good role model, and a good knowledge of both the research process and the analytical tools required.
- Published
- 2018
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18. Associations of lifestyle and diet with the risk of nasopharyngeal carcinoma in Singapore: a case-control study.
- Author
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Yong SK, Ha TC, Yeo MC, Gaborieau V, McKay JD, and Wee J
- Subjects
- Adult, Alcohol Drinking epidemiology, Carcinoma etiology, Case-Control Studies, Female, Humans, Life Style, Male, Middle Aged, Nasopharyngeal Carcinoma, Nasopharyngeal Neoplasms etiology, Odds Ratio, Risk Factors, Singapore epidemiology, Smoking epidemiology, Carcinoma epidemiology, Nasopharyngeal Neoplasms epidemiology, Smoking adverse effects, Sodium Chloride, Dietary adverse effects
- Abstract
Background: Nasopharyngeal carcinoma (NPC) is a commonly diagnosed cancer in Southeast Asia. Many studies have examined the risk factors for NPC, yet the roles of some risk factors remain inconclusive. The purpose of this study was to examine associations between modifiable lifestyle factors and the risk of NPC in the Singaporean population., Methods: We conducted a case-control study in Singapore with 300 patients and 310 controls who were recruited between 2008 and 2012. Each control was selected and individually matched to each patient based on sex, ethnicity, and age (±5 years). A total of 290 pairs of cases and controls were matched successfully. We examined lifestyle factors such as tobacco smoking, alcohol drinking, various salted and preserved food consumption, and weaning practices., Results: After adjusting for covariates, multivariate analysis showed that those participants who were current smokers and had ever smoked tobacco had a higher risk of NPC than participants who had never smoked, with odds ratios (ORs) of 4.50 (95% confidence interval [CI] 2.58-7.86; P < 0.001) and 2.52 (95% CI 1.54-4.12; P < 0.001), respectively. Those who consumed salted vegetables at least once a week also showed a significantly increased risk of NPC than those who never or rarely consumed salted vegetables, with an OR of 4.18 (95% CI 1.69-10.38; P = 0.002)., Conclusion: Smoking (currently and ever-smoked) and consuming salted vegetables once a week or more were lifestyle risk factors for NPC, and changes of these factors for the better may reduce the risk of NPC.
- Published
- 2017
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19. A 13-Year Single Institutional Experience with Definitive Radiotherapy in Hypopharyngeal Cancer.
- Author
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Sommat K, Yong SK, Fong KW, Tan TW, Wee JT, and Soong YL
- Subjects
- Adult, Age Factors, Aged, Aged, 80 and over, Carcinoma epidemiology, Carcinoma pathology, Disease-Free Survival, Female, Humans, Hypopharyngeal Neoplasms epidemiology, Hypopharyngeal Neoplasms pathology, Kaplan-Meier Estimate, Male, Middle Aged, Neoplasm Staging, Prognosis, Proportional Hazards Models, Radiotherapy, Adjuvant, Retrospective Studies, Sex Factors, Smoking epidemiology, Tumor Burden, Antineoplastic Agents therapeutic use, Carcinoma radiotherapy, Hypopharyngeal Neoplasms radiotherapy, Hypopharynx surgery, Radiotherapy, Intensity-Modulated
- Published
- 2017
20. Sulfur crosslinks from thermal degradation of chitosan dithiocarbamate derivatives and thermodynamic study for sorption of copper and cadmium from aqueous system.
- Author
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Yong SK, Skinner WM, Bolan NS, Lombi E, Kunhikrishnan A, and Ok YS
- Subjects
- Adsorption, Environmental Restoration and Remediation instrumentation, Hydrogen-Ion Concentration, Spectroscopy, Fourier Transform Infrared, Thermodynamics, Water Purification instrumentation, Cadmium chemistry, Chitosan chemistry, Copper chemistry, Environmental Restoration and Remediation methods, Sulfur chemistry, Water Pollutants, Chemical chemistry, Water Purification methods
- Abstract
Pristine chitosan beads were modified with sulfur (S)-containing functional groups to produce thiolated chitosan beads (ETB), thereby increasing S donor ligands and crosslinks. The effect of temperature, heating time, carbon disulfide (CS2)/chitosan ratio, and pH on total S content of ETB was examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The total S content of ETB increased with increasing CS2/chitosan ratio and decreased with decreasing pH and increasing temperature (>60 °C) and heating time (at 60 °C). Spectroscopic analyses revealed the presence of thiol (-SH)/thione, disulfide (-S-S-), and sulfonate groups in ETB. The thiolation mechanism involves decomposition of dithiocarbamate groups, thereby forming thiourea crosslinks and trithiocarbonate, resulting in -SH oxidation to produce -S-S- crosslinks. The partially formed ETB crosslinks contribute to its acid stability and are thermodynamically feasible in adsorbing Cd and Cu. The S-containing functional groups added to chitinous wastes act as sorbents for metal remediation from acidic environments.
- Published
- 2016
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21. Comparative study and systematic review of laparoscopic liver resection for hepatocellular carcinoma.
- Author
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Leong WQ, Ganpathi IS, Kow AW, Madhavan K, and Chang SK
- Abstract
Aim: To compare the surgical outcomes between laparoscopic liver resection (LLR) and open liver resection (OLR) as a curative treatment in patients with hepatocellular carcinoma (HCC)., Methods: A PubMed database search was performed systematically to identify comparative studies of LLR vs OLR for HCC from 2000 to 2014. An extensive text word search was conducted, using combinations of search headings such as "laparoscopy", "hepatectomy", and "hepatocellular carcinoma". A comparative study was also performed in our institution where we analysed surgical outcomes of 152 patients who underwent liver resection between January 2005 to December 2012, of which 42 underwent laparoscopic or hand-assisted laparoscopic resection and 110 underwent open resection., Results: Analysis of our own series and a review of 17 high-quality studies showed that LLR was superior to OLR in terms of short-term outcomes, as patients in the laparoscopic arm were found to have less intraoperative blood loss, less blood transfusions, and a shorter length of hospital stay. In our own series, both LLR and OLR groups were found to have similar overall survival (OS) rates, but disease-free survival (DFS) rates were higher in the laparoscopic arm., Conclusion: LLR is associated with better short-term outcomes compared to OLR as a curative treatment for HCC. Long-term oncologic outcomes with regards to OS and DFS rates were found to be comparable in both groups. LLR is hence a safe and viable option for curative resection of HCC.
- Published
- 2015
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22. A randomized controlled trial comparing post-operative pain in single-incision laparoscopic cholecystectomy versus conventional laparoscopic cholecystectomy.
- Author
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Chang SK, Wang YL, Shen L, Iyer SG, and Madhavan K
- Subjects
- Adult, Aged, Analgesics therapeutic use, Female, Humans, Male, Middle Aged, Operative Time, Pain Measurement, Patient Satisfaction, Reoperation, Statistics, Nonparametric, Time Factors, Umbilicus, Cholecystectomy, Laparoscopic adverse effects, Cholecystectomy, Laparoscopic methods, Pain, Postoperative etiology
- Abstract
Introduction: An increasing body of evidence is being published about single-incision laparoscopic cholecystectomy (SILC), but there are no well-powered trials with an adequate evaluation of post-operative pain. This randomized trial compares SILC against four-port laparoscopic cholecystectomy (LC) with post-operative pain as the primary endpoint., Methods: Hundred patients were randomized to either SILC (n = 50) or LC (n = 50). Exclusion criteria were (1) Acute cholecystitis; (2) ASA 3 or above; (3) Bleeding disorders; and (4) Previous open upper abdominal surgery. Patients and post-operative assessors were blinded to the procedure performed. The site and severity of pain were compared at 4 h, 24 h, 14 days and 6 months post-procedure using the visual analog scale; non-inferiority was assumed when the lower boundary of the 95% confidence interval of the difference was above -1 and superiority when p ≤ 0.05., Results: The study arms were demographically similar. At 24 h post-procedure, SILC was associated with less pain at extra-umbilical sites (rest: p = 0.004; movement: p = 0.008). Pain data were inconclusive at 24 h at the umbilical site on movement; SILC was otherwise non-inferior for pain at all other points. Operating duration was longer in SILC (79.46 vs 58.88 min, p = 0.003). 8% of patients in each arm suffered complications (p = 1.000). Re-intervention rates, analgesic use, return to function, and patient satisfaction did not differ significantly., Conclusions: SILC has improved short-term pain outcomes compared to LC and is not inferior in both short-term and long-term pain outcomes. The operating time is longer, but remains feasible in routine surgical practice.
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- 2015
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23. Environmental applications of chitosan and its derivatives.
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Yong SK, Shrivastava M, Srivastava P, Kunhikrishnan A, and Bolan N
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- Environmental Restoration and Remediation, Metals, Heavy chemistry, Organic Chemicals chemistry, Waste Disposal, Fluid, Chitosan chemistry, Soil Pollutants chemistry, Water Pollutants, Chemical chemistry
- Abstract
Chitosan originates from the seafood processing industry and is one of the most abundant of bio-waste materials. Chitosan is a by-product of the alkaline deacetylation process of chitin. Chemically, chitosan is a polysaccharide that is soluble in acidic solution and precipitates at higher pHs. It has great potential for certain environmental applications, such as remediation of organic and inorganic contaminants, including toxic metals and dyes in soil, sediment and water, and development of contaminant sensors. Traditionally, seafood waste has been the primary source of chitin. More recently, alternative sources have emerged such as fungal mycelium, mushroom and krill wastes, and these new sources of chitin and chitosan may overcome seasonal supply limitations that have existed. The production of chitosan from the above-mentioned waste streams not only reduces waste volume, but alleviates pressure on landfills to which the waste would otherwise go. Chitosan production involves four major steps, viz., deproteination, demineralization, bleaching and deacetylation. These four processes require excessive usage of strong alkali at different stages, and drives chitosan's production cost up, potentially making the application of high-grade chitosan for commercial remediation untenable. Alternate chitosan processing techniques, such as microbial or enzymatic processes, may become more cost-effective due to lower energy consumption and waste generation. Chitosan has proved to be versatile for so many environmental applications, because it possesses certain key functional groups, including - OH and -NH2 . However, the efficacy of chitosan is diminished at low pH because of its increased solubility and instability. These deficiencies can be overcome by modifying chitosan's structure via crosslinking. Such modification not only enhances the structural stability of chitosan under low pH conditions, but also improves its physicochemical characteristics, such as porosity, hydraulic conductivity, permeability, surface area and sorption capacity. Crosslinked chitosan is an excellent sorbent for trace metals especially because of the high flexibility of its structural stability. Sorption of trace metals by chitosan is selective and independent of the size and hardness of metal ions, or the physical form of chitosan (e.g., film, powder and solution). Both -OH and -NH2 groups in chitosan provide vital binding sites for complexing metal cations. At low pH, -NH3 + groups attract and coagulate negatively charged contaminants such as metal oxyanions, humic acids and dye molecules. Grafting certain functional molecules into the chitin structure improves sorption capacity and selectivity for remediating specific metal ions. For example, introducing sulfur and nitrogen donor ligands to chitosan alters the sorption preference for metals. Low molecular weight chitosan derivatives have been used to remediate metal contaminated soil and sediments. They have also been applied in permeable reactive barriers to remediate metals in soil and groundwater. Both chitosan and modified chitosan have been used to phytoremediate metals; however, the mechanisms by which they assist in mobilizing metals are not yet well understood. In addition, microbes have been used in combination with chitosan to remediate metals (e.g., Cu and Zn) in contaminated soils. Chitosan has also been used to remediate organic contaminants, such as oil-based wastewater, dyes, tannins, humic acids, phenols, bisphenoi-A, p-benzoquinone, organo-phosphorus insecticides, among others. Chitosan has also been utilized to develop optical and electrochemical sensors for in-situ detection of trace contaminants. In sensor technology, naturally-derived chitosan is used primarily as an immobilizing agent that results from its enzyme compatibility, and stabilizing effect on nanoparticles. Contaminant-sensing agents, such as enzymes, microbes and nanoparticles, have been homogeneously immobilized in chitosan gels by using coagulating (e.g., alginate, phosphate) or crosslinking agents (e.g., GA, ECH). Such immobilization maintains the stability of sensing elements in the chitosan gel phase, and prevents inactivation and loss of the sensing agent. In this review, we have shown that chitosan, an efficient by-product of a waste biomaterial, has great potential for many environmental applications. With certain limitations, chitosan and its derivatives can be used for remediating contaminated soil and wastewater. Notwithstanding, further research is needed to enhance the physicochemical properties of chitosan and mitigate its deficiencies.
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- 2015
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24. The effect of test kit provision, and individual and family education on the uptake rates of fecal occult blood test in an Asian population: a randomized controlled trial.
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Ha TC, Yong SK, Yeoh KW, Kamberakis K, Yeo RM, and Koh GC
- Subjects
- Aged, Aged, 80 and over, Asian People statistics & numerical data, Colorectal Neoplasms prevention & control, Family Characteristics, Female, Humans, Male, Mass Screening methods, Middle Aged, Occult Blood, Reagent Kits, Diagnostic, Singapore, Treatment Outcome, Colorectal Neoplasms diagnosis, Patient Education as Topic, Patient Participation
- Abstract
Purpose: The purpose of the study was to investigate whether fecal occult blood test (FOBT) home-delivery and individual education or combined with family education increases FOBT uptake rates in Singapore., Methods: This is a randomized controlled intervention study of Singaporean residents aged 50 years and above, conducted in May 2012 till May 2013. Eligible individuals in randomly selected households were screened, and one member was randomly selected and allocated to one of the four arms: Group A (individual and family education, FOBT kits provided), Group B (individual education only, FOBT kits provided), Group C (no education, FOBT kits provided) and Group D (no education or FOBT kits provided)., Results: Overall response rate was 74.7 %. The FOBT return rates for groups A, B, C and D were 24.5 % [CI 16.2-34.4 %], 25.3 % [CI 16.4-36.0 %], 10.7 % [CI 4.7-19.9 %] and 2.2 % [CI 0.3-7.7 %], respectively. Respondents who were provided education and home-delivered FOBT kits were 15 times more likely to return FOBT kits [Group A: OR 15.0 (3.4-66.2); Group B: OR 15.5 (3.5-68.8)] and those provided with home-delivered FOBT without education were five times more likely to return FOBT kits [Group C: OR 5.8 (1.2-28.3)] than those without education and FOBT kits (Group D). There was no significant difference in return of FOBT kits whether education was provided to subject with or without a family member., Conclusion: Home delivery of FOBT kits increased FOBT return rates and individual education combined with home-delivered FOBT increased FOBT return rates even further. However, additional combination with family education did not increase FOBT rates further.
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- 2014
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25. Therapeutic advances: single incision laparoscopic hepatopancreatobiliary surgery.
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Chang SK and Lee KY
- Subjects
- Clinical Competence, Hepatectomy adverse effects, Humans, Learning Curve, Operative Time, Pancreatectomy adverse effects, Postoperative Complications etiology, Risk Factors, Time Factors, Treatment Outcome, Cholecystectomy, Laparoscopic adverse effects, Hepatectomy methods, Laparoscopy adverse effects, Pancreatectomy methods
- Abstract
Single-port laparoscopic surgery (SPLS) is proposed to be a step towards minimizing the invasiveness of surgery, and has since gained popularity in several surgical sub-specialties including hepatopancreatobiliary surgery. SPLS has since been applied to cholecystectomy, liver resection as well as pancreatectomy for a multitude of pathologies. Benefits of SPLS over conventional multi-incision laparoscopic surgery include improved cosmesis and potentially post-operative pain at specific time periods and extra-umbilical sites. However, it is also associated with longer operating time, increased rate of complications, and increased rate of port-site hernia. There is no significant difference between length of hospital stay. SPLS has a significant learning curve that affects operating time, rate of conversion and rate of complications. In this article, we review the literature on SPLS in hepatobiliary surgery - cholecystectomy, hepatectomy and pancreatectomy, and offer tips on overcoming potential technical obstacles and minimizing the complications when performing SPLS - surgeon position, position of port and instruments, instrument crossing position, standard hand grip vs reverse hand grip, snooker cue guide position, prevention of incisional hernia. SPLS is a promising direction in laparoscopic surgery, and we recommend step-wise progression of applications of SPLS to various hepatopancreatobiliary surgeries to ensure safe adoption of the surgical technique.
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- 2014
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26. Single-incision laparoscopic hepatic resection in patients with previous hepatic resections: a mini case series.
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Kim G, Lau AC, and Chang SK
- Subjects
- Aged, Humans, Male, Middle Aged, Reoperation, Carcinoma, Hepatocellular surgery, Hepatectomy methods, Laparoscopy methods, Liver Neoplasms surgery
- Abstract
Single-incision laparoscopic hepatic resection has been attracting increased attention from the surgical community in recent years. While there have been reports and studies on this procedure, none has suggested the possibility of doing repeated hepatic resections via a single incision. This report on three such cases aims to determine the feasibility and safety of this approach for such patients. Three patients who had previously had liver resections underwent single-incision laparoscopic hepatic resection in our center. Patient demographics, type of port and instruments used, operating time, complications and incision length were collected. The operating time in each case was less than 230 min. The incision length for the single-port device was 3.5 cm or less. The length of hospital stay was less than 5 days in each case. Intra-operative blood loss was limited to 250 mL in each case. There were no immediate postoperative complications related to hepatic resection. Single-incision laparoscopic hepatic resection is feasible for selected patients who have had previous hepatic resections. Because the port entry site for the single-incision laparoscopic approach is usually slightly larger than that for the conventional approach, it is safer in re-resection cases where there may be adhesions from previous surgery. Other possible benefits, such as cosmesis and reduced port-associated morbidity, are mainly related to the use of only one small incision., (© 2014 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.)
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- 2014
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27. Projection-based visual guidance for robot-aided RF needle insertion.
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Wen R, Chui CK, Ong SH, Lim KB, and Chang SK
- Subjects
- Catheter Ablation instrumentation, Humans, Models, Anatomic, Software, Surgery, Computer-Assisted instrumentation, Catheter Ablation methods, Needles, Robotics instrumentation, Surgery, Computer-Assisted methods
- Abstract
Purpose: The use of projector-based augmented reality (AR) in surgery may enable surgeons to directly view anatomical models and surgical data from the patient's surface (skin). It has the advantages of a consistent viewing focus on the patient, an extended field of view and augmented interaction. This paper presents an AR guidance mechanism with a projector-camera system to provide the surgeon with direct visual feedback for supervision of robotic needle insertion in radiofrequency (RF) ablation treatment., Methods: The registration of target organ models to specific positions on the patient body is performed using a surface-matching algorithm and point-based registration. An algorithm based on the extended Kalman filter and spatial transformation is used to intraoperatively compute the virtual needle's depth in the patient's body for AR display., Results: Experiments of this AR system on a mannequin were conducted to evaluate AR visualization and accuracy of virtual RF needle insertion. The average accuracy of 1.86 mm for virtual needle insertion met the clinical requirement of 2 mm or better. The feasibility of augmented interaction with a surgical robot using the proposed open AR interface with active visual feedback was demonstrated., Conclusions: The experimental results demonstrate that this guidance system is effective in assisting a surgeon to perform a robot-assisted radiofrequency ablation procedure. The novelty of the work lies in establishing a navigational procedure for percutaneous surgical augmented intervention integrating a projection-based AR guidance and robotic implementation for surgical needle insertion.
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- 2013
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28. Diagnosis and management of pancreaticopleural fistula.
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Tay CM and Chang SK
- Subjects
- Cholangiopancreatography, Magnetic Resonance, Endoscopy, Humans, Male, Middle Aged, Pancreatic Ducts physiopathology, Pancreatic Fistula epidemiology, Pleural Diseases epidemiology, Treatment Outcome, Cholangiopancreatography, Endoscopic Retrograde adverse effects, Pancreatic Fistula diagnosis, Pancreatic Fistula therapy, Pleural Diseases diagnosis, Pleural Diseases therapy
- Abstract
Pancreaticopleural fistula is a rare diagnosis requiring a high index of clinical suspicion due to the predominant manifestation of thoracic symptoms. The current literature suggests that confirmation of elevated pleural fluid amylase is the most important diagnostic test. Magnetic resonance cholangiopancreatography is the recommended imaging modality to visualise the fistula, as it is superior to both computed tomography and endoscopic retrograde cholangiopancreatography (ERCP) in delineating the tract within the pancreatic region. It is also less invasive than ERCP. While a trial of medical regimen has traditionally been the first-line treatment, failure would result in higher rates of complications. Hence, it is suggested that management strategies be planned based on pancreatic ductal imaging, with patients having poor chances of spontaneous closure undergoing either endoscopic or surgical intervention. We also briefly describe a case of pancreaticopleural fistula in a patient who was treated using a modified Puestow procedure after failed endoscopic treatment.
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- 2013
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29. Interim report: a randomized controlled trial comparing postoperative pain in single-incision laparoscopic cholecystectomy and conventional laparoscopic cholecystectomy.
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Chang SK, Wang YL, Shen L, Iyer SG, Shaik AB, and Lomanto D
- Subjects
- Adult, Cholecystectomy, Laparoscopic methods, Double-Blind Method, Female, Gallbladder Diseases complications, Gallbladder Diseases pathology, Humans, Length of Stay, Male, Middle Aged, Pain Measurement, Pain, Postoperative diagnosis, Pain, Postoperative etiology, Patient Satisfaction, Recovery of Function, Time Factors, Treatment Outcome, Cholecystectomy, Laparoscopic adverse effects, Gallbladder Diseases surgery, Pain, Postoperative prevention & control
- Abstract
Introduction: Single-incision laparoscopic cholecystectomy (SILC) is increasingly practiced, but there have been no well-powered randomized trials investigating the technique. This non-inferiority trial aims to compare SILC with conventional four-port laparoscopic cholecystectomy (LC) with postoperative pain as the primary endpoint., Methods: We aim to randomize 100 patients into equal arms of SILC or LC. Exclusion criteria were: (i) acute cholecystitis; (ii) an ASA score of 3 or above; (iii) bleeding disorders; or (iv) previous upper abdominal surgery. Patients and postoperative assessors were blinded to the procedure received. The site and severity of pain was compared based on the visual analogue scale at 4 hours, 24 hours and 14 days postoperatively; non-inferiority was assumed when the lower boundary of the 95% confidence interval of the difference was above -1, and superiority when P ≤ 0.05., Results: We recruited 24 SILC and 26 LC patients. There were no conversions to open cholecystectomy or from SILC to LC. SILC was non-inferior for pain at umbilical sites at rest and at extra-umbilical sites at all times. At 24 hours postoperatively, SILC was associated with significantly less pain at extra-umbilical sites (rest: P = 0.002; movement: P = 0.004). There were no incidents of biliary injury or retained gallstones. Of the 24 SILC patients, 12.5% had postoperative complications (vomiting, mild fluid overload, wound infection) compared with 0% of LC patients (P = 0.110); all complications resolved with conservative management. Operating time, analgesic use, return to function, and overall satisfaction did not differ significantly between the two groups., Conclusion: SILC is associated with reduced pain and is feasible in routine surgical practice., (© 2012 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.)
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- 2013
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30. SILC for SILC: Single Institution Learning Curve for Single-Incision Laparoscopic Cholecystectomy.
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Tay CW, Shen L, Hartman M, Iyer SG, Madhavan K, and Chang SK
- Abstract
Objectives. We report the single-incision laparoscopic cholecystectomy (SILC) learning experience of 2 hepatobiliary surgeons and the factors that could influence the learning curve of SILC. Methods. Patients who underwent SILC by Surgeons A and B were studied retrospectively. Operating time, conversion rate, reason for conversion, identity of first assistants, and their experience with previous laparoscopic cholecystectomy (LC) were analysed. CUSUM analysis is used to identify learning curve. Results. Hundred and nineteen SILC cases were performed by Surgeons A and B, respectively. Eight cases required additional port. In CUSUM analysis, most conversion occurred during the first 19 cases. Operating time was significantly lower (62.5 versus 90.6 min, P = 0.04) after the learning curve has been overcome. Operating time decreases as the experience increases, especially Surgeon B. Most conversions are due to adhesion at Calot's triangle. Acute cholecystitis, patients' BMI, and previous surgery do not seem to influence conversion rate. Mean operating times of cases assisted by first assistant with and without LC experience were 48 and 74 minutes, respectively (P = 0.004). Conclusion. Nineteen cases are needed to overcome the learning curve of SILC. Team work, assistant with CLC experience, and appropriate equipment and technique are the important factors in performing SILC.
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- 2013
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31. Intestinal obstruction in pregnancy: a case report.
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Rauff S, Chang SK, and Tan EK
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Background. Intestinal obstruction in pregnancy is uncommon. The condition is associated with significant maternal and fetal mortality. The delay in diagnosis is due to nonspecific symptoms and a disinclination to carry out radiologic investigations in pregnancy. Case. A 39-year-old lady at 32 weeks of gestation presented with abdominal pain and nausea. Her symptoms worsened during admission. A computed tomography (CT) scan showed dilated small bowel loops suggestive of intestinal obstruction. She eventually underwent a laparotomy as conservative measures failed. Conclusion. A high index of clinical suspicion is required to diagnose intestinal obstruction in pregnancy. Prompt diagnosis should be made and the appropriate treatment instituted. Surgical intervention should be performed if necessary as further delay only results in increased morbidity and mortality.
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- 2013
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32. Laparoendoscopic single-site minor hepatectomy for liver tumors.
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Tan EK, Lee VT, Chang SK, Ganpathi IS, Madhavan K, and Lomanto D
- Subjects
- Aged, Blood Loss, Surgical, Feasibility Studies, Female, Humans, Length of Stay, Magnetic Resonance Imaging, Male, Middle Aged, Carcinoma, Hepatocellular surgery, Endoscopy, Digestive System methods, Hepatectomy methods, Laparoscopy methods, Liver Neoplasms surgery
- Abstract
Background: Laparoscopic liver surgery is gaining increasing acceptance worldwide, but its frontiers are constantly challenged. Laparoendoscopic single-site surgery (LESS) has been performed for various organs, but the feasibility of LESS hepatectomies has yet to be explored fully., Methods: From May 2010 to March 2011, seven patients underwent LESS minor hepatectomies. Patient demographic, operative, and clinical data were reviewed., Results: Five left lateral sectionectomies, one segment 3, and one segment 5 resection were performed. The median operative time was 142 min (range, 104-171 min), and the median blood loss was 200 ml (range, 100-450 ml). The median hospital stay was 3 days (range, 1-11 days). For all the patients, the indications for surgery were suspected malignant tumors, and the surgical resection margins were clear for every patient., Conclusions: Laparoendoscopic single-site minor hepatectomy is a novel modification to traditional laparoscopic surgery. The method is safe and feasible without any compromise to oncologic safety for selected patients with hepatocellular carcinoma (HCC) and colorectal liver metastases that are peripheral and smaller than 5 cm in size.
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- 2012
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33. Early experience in single-site laparoscopic cholecystectomy.
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Chang SK, Tan SS, and Kok YO
- Subjects
- Aged, Biliary Tract Diseases diagnosis, Biliary Tract Diseases surgery, Colic diagnosis, Colic surgery, Equipment Design, Humans, Laparoscopes, Middle Aged, Prospective Studies, Risk, Surgical Procedures, Operative methods, Treatment Outcome, Cholecystectomy, Laparoscopic instrumentation, Cholecystectomy, Laparoscopic methods, Gallbladder Diseases diagnosis, Gallbladder Diseases surgery, Gastroenterology methods
- Abstract
Introduction: Laparoscopic cholecystectomy is currently the gold standard for removal of symptomatic gallbladders. The push in recent years toward reducing the number of ports required to perform this surgery has led to the development of single-incision laparoscopic cholecystectomy (SILC). We report our early experience with SILC and assess its feasibility and safety., Methods: A prospective study was conducted of the first 100 patients who presented with complaints of biliary colic and underwent laparoscopic cholecystectomy via the single-port technique at our institution. SILC was performed via a single-port device such as a flexible umbilical port that could accommodate up to three surgical instruments. The port was inserted into a transumbilical incision around 15-20 mm long. Data on operative details and postoperative outcomes were collected and evaluated., Results: The mean operation time was 67.8 minutes. Six patients needed conversion, requiring extra 5-mm ports to complete the surgery. No serious intraoperative complications, such as bile duct injury or bile leakage, were encountered. Cosmesis from the scar hidden within the umbilical fold was excellent., Conclusion: Our initial results of single-port laparoscopic cholecystectomy are promising, with no complications being seen in this early series. However, the drawbacks include the higher cost of equipment and a steeper learning curve. Further evaluation is required to assess the risks and benefits of this approach when compared with conventional laparoscopic cholecystectomy.
- Published
- 2012
34. Integrated ablation and division device for liver resection.
- Author
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Chang SK, Hlaing WW, Huang WH, and Chui CK
- Subjects
- Animals, Feasibility Studies, Laparoscopy instrumentation, Laparoscopy methods, Liver blood supply, Models, Animal, Swine, Blood Loss, Surgical prevention & control, Catheter Ablation instrumentation, Catheter Ablation methods, Liver surgery
- Abstract
Background: Intraoperative blood loss during liver resection may be minimized by ablating the liver parenchyma using radiofrequency (RF) energy. However, it is difficult to estimate the depth of the avascular plane and more RF energy than necessary may be inadvertently used as a result of lack of feedback., Methods: Laparoscopic liver resection was performed on a live porcine model to determine the feasibility and applicability of a model which integrates ablation and division in a single device., Results: Liver resection was uncomplicated with minimal bleeding. The integration of the ablation and division mechanism resolved the difficulty of estimating the depth of the avascular plane after coagulation. The real-time feedback mechanism minimized liver damage by eliminating the application of unnecessary RF., Conclusions: The proposed model is functionally acceptable and represents a possible method of determining the depth of the avascular plane and the amount of RF energy required during liver resection., (© 2010 International Hepato-Pancreato-Biliary Association.)
- Published
- 2011
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35. A case-control study of single-incision versus standard laparoscopic cholecystectomy.
- Author
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Chang SK, Tay CW, Bicol RA, Lee YY, and Madhavan K
- Subjects
- Adult, Aged, Case-Control Studies, Female, Humans, Male, Middle Aged, Retrospective Studies, Young Adult, Cholecystectomy methods, Cholecystectomy, Laparoscopic
- Abstract
Background: Single-incision laparoscopic cholecystectomy (SILC) has been increasingly performed recently. Although it seems plausible that SILC will be associated with less pain compared to standard 4-port laparoscopic cholecystectomy (LC), there is currently no conclusive comparative study on the postoperative pain issues of SILC against LC., Methods: In this retrospective, case-control study, 30 patients who had SILC over a 6-month period were compared with a matched (sex, age group, race) group of 30 patients who underwent LC. Verbal pain score (VPS) on postoperative days (POD) 1, 2, 3, and 5; pain sites; analgesic requirement; and number of days (NoD) required to return to normal activities were compared., Results: There were 4 (13%) acute cholecystitis cases in each group. Average VPS on POD 1, 2, 3, and 5 of SILC and (LC) cholecystectomy patients were 4.53 (5.14) (P=0.09), 3.43 (3.83) (P=0.36), 2.07 (2.52) (P=0.25), and 1.13 (1.24) (P=0.69), respectively. In the SILC group, 26 patients (87%) had umbilical pain, whereas in the LC group, 25 patients (83%) had similar symptoms. Epigastric pain was experienced by 5 patients in the two groups, and RHC pain was experienced by 1 patient in the SILC group (3%) and 2 patients in the LC group (7%). The SILC and the LC patients required 4.00 and 4.90 days (P=0.09) of paracetamol, respectively, to control pain. The NoD required before return to normal activity in the SILC and LC groups was 5.97 days and 7.79 days (P=0.008), respectively., Conclusions: There was no statistically significant difference in postoperative pain, pain site and analgesia requirement; however, patients who underwent SILC returned to their normal activity 1.8 days earlier than the LC patients. Larger RCTs are needed to compare postoperative outcomes between SILC and LC.
- Published
- 2011
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36. Pleurotus ostreatus spent mushroom compost as green biosorbent for nickel (II) biosorption.
- Author
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Tay CC, Liew HH, Redzwan G, Yong SK, Surif S, and Abdul-Talib S
- Subjects
- Adsorption, Hydrogen-Ion Concentration, Time Factors, Water chemistry, Water Pollutants, Chemical chemistry, Water Purification, Green Chemistry Technology, Nickel chemistry, Pleurotus physiology, Soil chemistry
- Abstract
The potential of Pleurotus ostreatus spent mushroom compost (PSMC) as a green biosorbent for nickel (II) biosorption was investigated in this study. A novel approach of using the half-saturation concentration of biosorbent to rapidly determine the uptake, kinetics and mechanism of biosorption was employed together with cost per unit uptake analysis to determine the potential of this biosorbent. Fifty per cent nickel (II) biosorption was obtained at a half-saturation constant of 0.7 g biosorbent concentration, initial pH in the range of 4-8, 10 min contact time, 50 mL 50 mg/L nickel (II) initial concentration. The experimental data were well fitted with the Langmuir isotherm model and the maximum nickel (II) biosorption was 3.04 mg/g. The results corresponded well to a second pseudo order kinetic model with the coefficient of determination value of 0.9999. Based on FTIR analysis, the general alkyl, hydroxyl or amino, aliphatic alcohol and carbonyl functional groups of biosorbent were involved in the biosorption process. Therefore, biosorption of nickel (II) must involve several mechanisms simultaneously such as physical adsorption, chemisorption and ion exchange. Cost comparison for PSMC with Amberlite IRC-86 ion exchange resin indicates that the biosorbent has the potential to be developed into a cost effective and environmentally friendly treatment system.
- Published
- 2011
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37. Single port laparoscopic liver resection for hepatocellular carcinoma: a preliminary report.
- Author
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Chang SK, Mayasari M, Ganpathi IS, Wen VL, and Madhavan K
- Abstract
Single port laparoscopic surgery is an emerging technique, now commonly used in cholecystectomy. The experience of using this technique in liver resection for hepatocellular carcinoma is described in a series of 3 cases with single port laparoscopic liver resection performed during 2010. All patients were male aged 61 to 70 years, with several comorbidities. There were no complications in this early series. The length of hospital stay was 3-5 days. The blood loss was 200-450 mL, with operating time between 142 and 171 minutes. We conclude that this technique is feasible and safe to perform in experienced centers.
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- 2011
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38. Enhanced sensitivity of celecoxib in human glioblastoma cells: Induction of DNA damage leading to p53-dependent G1 cell cycle arrest and autophagy.
- Author
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Kang KB, Zhu C, Yong SK, Gao Q, and Wong MC
- Subjects
- Analysis of Variance, Benzothiazoles pharmacology, Blotting, Western, Celecoxib, Cell Line, Tumor, Cell Proliferation drug effects, Cell Survival drug effects, Comet Assay, Cyclin-Dependent Kinase Inhibitor p21 genetics, Cyclin-Dependent Kinase Inhibitor p21 metabolism, Cyclooxygenase Inhibitors pharmacology, Dose-Response Relationship, Drug, Humans, Immunohistochemistry, Resting Phase, Cell Cycle drug effects, Reverse Transcriptase Polymerase Chain Reaction, Toluene analogs & derivatives, Toluene pharmacology, Tumor Suppressor Protein p53 genetics, Autophagy drug effects, DNA Damage, G1 Phase drug effects, Pyrazoles pharmacology, Sulfonamides pharmacology, Tumor Suppressor Protein p53 metabolism
- Abstract
Background: Selective cyclooxygenase (COX)-2 inhibitors elicit anti-proliferative responses in various tumours, however the underlying anti-tumour mechanisms are unclear. Mutational inactivation of the tumour suppressor p53 gene is frequent in malignant gliomas. The role of p53 mutation in the anti-tumour responses of the selective COX-2 inhibitor celecoxib in human glioblastoma cells is unknown. In this study, we used human glioblastoma cells with various p53 status; U87MG (with high and low p53 functional levels), LN229 (functional p53) and U373MG (mutant p53) cells. Inhibition of p53 was achieved in U87MG cells transfected with E6 oncoprotein (U87MG-E6) and treated with pifithrin-alpha, a reversible inhibitor of p53 (U87MG-PFT). We investigated whether the anti-glioblastoma responses of celecoxib were p53-dependent, and whether celecoxib induced DNA damage leading to p53-dependent G1 cell cycle arrest, followed by autophagy or apoptosis., Results: Our findings demonstrated that celecoxib concentration-dependently reduced glioblastoma cell viability, following 24 and 72 hours of treatment. Inhibition of functional p53 in glioblastoma cells significantly reduced the anti-proliferative effect of celecoxib. In U87MG cells, celecoxib (8 and 30 muM) significantly induced DNA damage and inhibited DNA synthesis, corresponding with p53 activation. Celecoxib induced G1-phase cell cycle arrest, accompanied with p21 activation in U87MG cells. Cell cycle progression of U87MG-E6 and U87MG-PFT cells was not affected by celecoxib. In parallel, celecoxib induced G1 cell cycle arrest in LN229 cells, but not in U373MG cells. Autophagy was induced by celecoxib in U87MG and LN229 cells, as shown by the significantly greater population of acridine orange-stained cells and increased levels of LC3-II protein (in comparison with non-treated controls). Celecoxib did not induce significant autophagy in U87MG-PFT, U87MG-E6 and U373MG cells, which lack functional p53. Regardless of p53 status, celecoxib caused no significant difference in apoptosis level of U87MG, U87MG-PFT, U87MG-E6 and U373MG cells., Conclusion: Our findings reveal that p53 increases human glioblastoma sensitivity to celecoxib. Celecoxib inhibits glioblastoma cell viability by induction of DNA damage, leading to p53-dependent G1 cell cycle arrest and p53-dependent autophagy, but not apoptosis.
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- 2009
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39. Cardiac malformations are associated with altered expression of vascular endothelial growth factor and endothelial nitric oxide synthase genes in embryos of diabetic mice.
- Author
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Kumar SD, Yong SK, Dheen ST, Bay BH, and Tay SS
- Subjects
- Animals, Apoptosis, Cell Proliferation, Cells, Cultured, Female, Glucose pharmacology, Heart Defects, Congenital pathology, Heart Defects, Congenital ultrastructure, Mice, Myoblasts, Cardiac cytology, Myoblasts, Cardiac drug effects, Myoblasts, Cardiac metabolism, Myocardium enzymology, Myocardium metabolism, Myocardium pathology, RNA, Messenger metabolism, Rats, Diabetes Mellitus, Experimental genetics, Embryonic Development genetics, Heart embryology, Heart Defects, Congenital genetics, Nitric Oxide Synthase genetics, Vascular Endothelial Growth Factor A genetics
- Abstract
The aim of this study was to investigate the role of nitric oxide (NO), and the expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) genes in developing hearts at embryonic day 13.5 of embryos from diabetic mice. The protein and mRNA expression levels of eNOS and VEGF were significantly altered in the developing hearts of embryos from diabetic mice. The NO level was significantly decreased, whereas the VEGF concentration was significantly increased in the developing hearts of the embryos from diabetic mice. In vitro study showed a significant reduction in eNOS expression and cell proliferation in cardiac myoblast cells exposed to high glucose concentrations. Further, high glucose induced apoptosis in myoblast cells. Ultrastructural changes characteristics of apoptosis, including cell blebbing, aggregation of ribosomes and vacuoles in the cytoplasm were also evident in myoblast cells exposed to high glucose. It is suggested that hyperglycemia alters the expression of eNOS and VEGF genes that are involved in the regulation of cell growth and vasculogenesis, thereby contributing to the cardiac malformations seen in embryos from diabetic mice.
- Published
- 2008
- Full Text
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