1
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Joshi J, Jately V, Kala P, Sharma A, Lim WH, Azzopardi B. Control strategy for current limitation and maximum capacity utilization of grid connected PV inverter under unbalanced grid conditions. Sci Rep 2024; 14:10118. [PMID: 38698069 PMCID: PMC11066046 DOI: 10.1038/s41598-024-60244-x] [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: 05/30/2023] [Accepted: 04/19/2024] [Indexed: 05/05/2024] Open
Abstract
Under grid voltage sags, over current protection and exploiting the maximum capacity of the inverter are the two main goals of grid-connected PV inverters. To facilitate low-voltage ride-through (LVRT), it is imperative to ensure that inverter currents are sinusoidal and remain within permissible limits throughout the inverter operation. An improved LVRT control strategy for a two-stage three-phase grid-connected PV system is presented here to address these challenges. To provide over current limitation as well as to ensure maximum exploitation of the inverter capacity, a control strategy is proposed, and performance the strategy is evaluated based on the three generation scenarios on a 2-kW grid connected PV system. An active power curtailment (APC) loop is activated only in high power generation scenario to limit the current's amplitude below the inverter's rated current. The superior performance of the proposed strategy is established by comparison with two recent LVRT control strategies. The proposed method not only injects necessary active and reactive power but also minimizes overcurrent with increased exploitation of the inverter's capacity under unbalanced grid voltage sag.
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Affiliation(s)
- Jyoti Joshi
- Department of Computer Science and Engineering, Graphic Era Hill University, Dehra Dun, 248002, India
| | - Vibhu Jately
- Department of Electrical & Electronics Engineering, School of Engineering, University of Petroleum and Energy Studies, Dehra Dun, 248007, India.
| | - Peeyush Kala
- Department of Electrical and Electronics Engineering, SRM Institute of Science and Technology, Delhi NCR Campus, Ghaziabad, Uttar Pradesh, 201204, India.
| | - Abhishek Sharma
- Department of Computer Science and Engineering, Graphic Era Deemed to Be University, Dehra Dun, 248002, India
| | - Wei Hong Lim
- Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Cheras, Kuala Lumpur, Malaysia
| | - Brian Azzopardi
- The Foundation for Innovation and Research - Malta, 65 Design Centre Level 2, Tower Road, Birkirkara, BKR 4012, Malta
- MCAST Energy Research Group, Institute of Engineering and Transport, Malta College of Arts, Science and Technology (MCAST), Main Campus, Corradino Hill, Paola, PLA9032, Malta
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2
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Rahman H, Khan AR, Sadiq T, Farooqi AH, Khan IU, Lim WH. A Systematic Literature Review of 3D Deep Learning Techniques in Computed Tomography Reconstruction. Tomography 2023; 9:2158-2189. [PMID: 38133073 PMCID: PMC10748093 DOI: 10.3390/tomography9060169] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 10/13/2023] [Revised: 11/27/2023] [Accepted: 12/01/2023] [Indexed: 12/23/2023] Open
Abstract
Computed tomography (CT) is used in a wide range of medical imaging diagnoses. However, the reconstruction of CT images from raw projection data is inherently complex and is subject to artifacts and noise, which compromises image quality and accuracy. In order to address these challenges, deep learning developments have the potential to improve the reconstruction of computed tomography images. In this regard, our research aim is to determine the techniques that are used for 3D deep learning in CT reconstruction and to identify the training and validation datasets that are accessible. This research was performed on five databases. After a careful assessment of each record based on the objective and scope of the study, we selected 60 research articles for this review. This systematic literature review revealed that convolutional neural networks (CNNs), 3D convolutional neural networks (3D CNNs), and deep learning reconstruction (DLR) were the most suitable deep learning algorithms for CT reconstruction. Additionally, two major datasets appropriate for training and developing deep learning systems were identified: 2016 NIH-AAPM-Mayo and MSCT. These datasets are important resources for the creation and assessment of CT reconstruction models. According to the results, 3D deep learning may increase the effectiveness of CT image reconstruction, boost image quality, and lower radiation exposure. By using these deep learning approaches, CT image reconstruction may be made more precise and effective, improving patient outcomes, diagnostic accuracy, and healthcare system productivity.
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Affiliation(s)
- Hameedur Rahman
- Department of Computer Games Development, Faculty of Computing & AI, Air University, E9, Islamabad 44000, Pakistan;
| | - Abdur Rehman Khan
- Department of Creative Technologies, Faculty of Computing & AI, Air University, E9, Islamabad 44000, Pakistan;
| | - Touseef Sadiq
- Centre for Artificial Intelligence Research, Department of Information and Communication Technology, University of Agder, Jon Lilletuns vei 9, 4879 Grimstad, Norway
| | - Ashfaq Hussain Farooqi
- Department of Computer Science, Faculty of Computing AI, Air University, Islamabad 44000, Pakistan;
| | - Inam Ullah Khan
- Department of Electronic Engineering, School of Engineering & Applied Sciences (SEAS), Isra University, Islamabad Campus, Islamabad 44000, Pakistan;
| | - Wei Hong Lim
- Faculty of Engineering, Technology and Built Environment, UCSI University, Kuala Lumpur 56000, Malaysia;
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3
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Ang KM, Lim WH, Tiang SS, Sharma A, Eid MM, Tawfeek SM, Khafaga DS, Alharbi AH, Abdelhamid AA. Optimizing Image Classification: Automated Deep Learning Architecture Crafting with Network and Learning Hyperparameter Tuning. Biomimetics (Basel) 2023; 8:525. [PMID: 37999166 PMCID: PMC10669013 DOI: 10.3390/biomimetics8070525] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/25/2023] Open
Abstract
This study introduces ETLBOCBL-CNN, an automated approach for optimizing convolutional neural network (CNN) architectures to address classification tasks of varying complexities. ETLBOCBL-CNN employs an effective encoding scheme to optimize network and learning hyperparameters, enabling the discovery of innovative CNN structures. To enhance the search process, it incorporates a competency-based learning concept inspired by mixed-ability classrooms during the teacher phase. This categorizes learners into competency-based groups, guiding each learner's search process by utilizing the knowledge of the predominant peers, the teacher solution, and the population mean. This approach fosters diversity within the population and promotes the discovery of innovative network architectures. During the learner phase, ETLBOCBL-CNN integrates a stochastic peer interaction scheme that encourages collaborative learning among learners, enhancing the optimization of CNN architectures. To preserve valuable network information and promote long-term population quality improvement, ETLBOCBL-CNN introduces a tri-criterion selection scheme that considers fitness, diversity, and learners' improvement rates. The performance of ETLBOCBL-CNN is evaluated on nine different image datasets and compared to state-of-the-art methods. Notably, ELTLBOCBL-CNN achieves outstanding accuracies on various datasets, including MNIST (99.72%), MNIST-RD (96.67%), MNIST-RB (98.28%), MNIST-BI (97.22%), MNST-RD + BI (83.45%), Rectangles (99.99%), Rectangles-I (97.41%), Convex (98.35%), and MNIST-Fashion (93.70%). These results highlight the remarkable classification accuracy of ETLBOCBL-CNN, underscoring its potential for advancing smart device infrastructure development.
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Affiliation(s)
- Koon Meng Ang
- Faculty of Engineering, Technology and Built Environment, UCSI University, Kuala Lumpur 56000, Malaysia; (K.M.A.); (S.S.T.)
| | - Wei Hong Lim
- Faculty of Engineering, Technology and Built Environment, UCSI University, Kuala Lumpur 56000, Malaysia; (K.M.A.); (S.S.T.)
| | - Sew Sun Tiang
- Faculty of Engineering, Technology and Built Environment, UCSI University, Kuala Lumpur 56000, Malaysia; (K.M.A.); (S.S.T.)
| | - Abhishek Sharma
- Department of Computer Science and Engineering, Graphic Era Deemed to be University, Dehradun 248002, India;
| | - Marwa M. Eid
- Delta Higher Institute for Engineering and Technology, Mansoura 35511, Egypt;
- Faculty of Artificial Intelligence, Delta University for Science and Technology, Mansoura 35111, Egypt
| | - Sayed M. Tawfeek
- Delta Higher Institute for Engineering and Technology, Mansoura 35511, Egypt;
| | - Doaa Sami Khafaga
- Department of Computer Sciences, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia; (D.S.K.); (A.H.A.)
| | - Amal H. Alharbi
- Department of Computer Sciences, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia; (D.S.K.); (A.H.A.)
| | - Abdelaziz A. Abdelhamid
- Department of Computer Science, Faculty of Computer and Information Sciences, Ain Shams University, Cairo 11566, Egypt;
- Department of Computer Science, College of Computing and Information Technology, Shaqra University, Sahqra 11961, Saudi Arabia
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Fang X, Chiong MC, Jiang X, Yu LJ, Chen X, Muhieldeen MW, Al-Talib AAM, Lim WH, Wong KY. Energy-economy-environment assessments of refrigerants R152a and R134a in a vapor compression refrigeration system using a variable displacement oil-free linear compressor. Environ Sci Pollut Res Int 2023; 30:101223-101233. [PMID: 37648923 DOI: 10.1007/s11356-023-29521-6] [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] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 08/22/2023] [Indexed: 09/01/2023]
Abstract
In light of the adverse environmental impact of the R134a refrigerant, replacing it with a more environmentally friendly refrigerant has become imperative than ever. This study presents an experimental investigation into the utilization of R152a and R134a refrigerants in a vapor compression refrigeration system employing a variable displacement oil-free linear compressor. The potential for the replacement of R134a with R152a was examined based on energy, environmental, and economic performance analyses. The outcomes indicated that R152a exhibited a higher coefficient of performance (COP) in comparison to R134a under identical operating conditions. Specifically, when the pressure ratio was 2.0 and the piston stroke was 11 mm, R152a's COP was 13.0% higher than R134a. It was also discovered that reducing the operating stroke and increasing the pressure ratio could effectively lower CO2 emissions and total costs. Under the 2.0 pressure ratio and 9-mm piston stroke, R134a produced 1082.4 kg more CO2 emissions than R152a, representing a 209% increase. In addition, the R152a and R134a total cost was reduced by 8.3% with the 2.5 pressure ratio and 11-mm piston stroke. Notably, the results of the current study demonstrated that R152a outperformed R134a in energy consumption, environmental friendliness, and economy in oil-free linear compressor refrigeration systems. R152a used less electric power, generated fewer CO2 emissions, and naturally reduced predicted running costs in order to maintain the same COP.
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Affiliation(s)
- Xueliang Fang
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
- College of Traffic Engineering, Yangzhou Polytechnic Institute, Yangzhou, 225127, China
| | - Meng-Choung Chiong
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia.
| | - Xinyue Jiang
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Lih Jiun Yu
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Xinwen Chen
- School of Automotive Studies, Tongji University, Shanghai, 201804, China
| | - Mohammed W Muhieldeen
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Ammar Abdulaziz Majeed Al-Talib
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Wei Hong Lim
- Department of Mechanical Engineering, Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Keng Yinn Wong
- School of Mechanical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru, Johor, Malaysia
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Sharma A, Sharma A, Averbukh M, Jately V, Rajput S, Azzopardi B, Lim WH. Performance investigation of state-of-the-art metaheuristic techniques for parameter extraction of solar cells/module. Sci Rep 2023; 13:11134. [PMID: 37429876 DOI: 10.1038/s41598-023-37824-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 06/28/2023] [Indexed: 07/12/2023] Open
Abstract
One of the greatest challenges for widespread utilization of solar energy is the low conversion efficiency, motivating the needs of developing more innovative approaches to improve the design of solar energy conversion equipment. Solar cell is the fundamental component of a photovoltaic (PV) system. Solar cell's precise modelling and estimation of its parameters are of paramount importance for the simulation, design, and control of PV system to achieve optimal performances. It is nontrivial to estimate the unknown parameters of solar cell due to the nonlinearity and multimodality of search space. Conventional optimization methods tend to suffer from numerous drawbacks such as a tendency to be trapped in some local optima when solving this challenging problem. This paper aims to investigate the performance of eight state-of-the-art metaheuristic algorithms (MAs) to solve the solar cell parameter estimation problem on four case studies constituting of four different types of PV systems: R.T.C. France solar cell, LSM20 PV module, Solarex MSX-60 PV module, and SS2018P PV module. These four cell/modules are built using different technologies. The simulation results clearly indicate that the Coot-Bird Optimization technique obtains the minimum RMSE values of 1.0264E-05 and 1.8694E-03 for the R.T.C. France solar cell and the LSM20 PV module, respectively, while the wild horse optimizer outperforms in the case of the Solarex MSX-60 and SS2018 PV modules and gives the lowest value of RMSE as 2.6961E-03 and 4.7571E-05, respectively. Furthermore, the performances of all eight selected MAs are assessed by employing two non-parametric tests known as Friedman ranking and Wilcoxon rank-sum test. A full description is also provided, enabling the readers to understand the capability of each selected MA in improving the solar cell modelling that can enhance its energy conversion efficiency. Referring to the results obtained, some thoughts and suggestions for further improvements are provided in the conclusion section.
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Affiliation(s)
- Abhishek Sharma
- Department of Computer Science and Engineering, Graphic Era Deemed to Be University, Dehradun, 248002, India
| | - Abhinav Sharma
- Department of Electrical and Electronics Engineering, University of Petroleum and Energy Studies, Dehradun, 248007, India
| | - Moshe Averbukh
- Department of Electrical and Electronics Engineering, Ariel University, 40700, Ariel, Israel
| | - Vibhu Jately
- Department of Electrical and Electronics Engineering, University of Petroleum and Energy Studies, Dehradun, 248007, India
| | - Shailendra Rajput
- College of Engineering, Xi'an International University, Xi'an, 710077, China
| | - Brian Azzopardi
- MCAST Energy Research Group (MCAST Energy), Institute of Engineering and Transport, Malta College of Arts, Science and Technology (MCAST), Triq Kordin, Paola, PLA 9032, Malta
- The Foundation for Innovation and Research - Malta, 65 Design Centre Level 2, Tower Road, BKR 4012, Birkirkara, Malta
| | - Wei Hong Lim
- Faculty of Engineering, Technology and Built Environment, UCSI University, 56000, Cheras, Kuala Lumpur, Malaysia.
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6
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Lim OZH, Chen Y, Dimmeler S, Yong AWJ, Singh H, Sim MLE, Kong G, Lim WH, Low TT, Park DW, Chew NWS, Foo R. Disparity in female and Asian representation amongst cardiology journal editorial boards members: a call for empowerment. QJM 2022; 115:830-836. [PMID: 35866641 DOI: 10.1093/qjmed/hcac176] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND While progress is evident in gender and ethnic representation in the workplace, this disparity remains prevalent in academic positions. OBJECTIVES We examined gender and Asian ethnic representation in editorial boards of cardiology journals. METHODS A cross-sectional analysis was conducted using publicly available data on Cardiology and Cardiovascular medicine journals in the first quartile of the 2020 Scimago Journal & Country Rank indicator. The proportions of female and Asian editorial board members, associate editors and editors-in-chief were assessed. Subgroup analyses were conducted based on the journal's geographical origin, subspecialty and demographic of the editor-in-chief. RESULTS Seventy-six cardiology journals, involving 8915 editorial board members, were included. Only 19.6% of editorial board members were female, 20.8% Asians and 4.0% Asian females. There were less female representation amongst editors-in-chief (9.9%) compared to associate editors (22.3%). European (18.1%) and North American-based journals (21.1%) had higher female representation compared to Asian-based journals (8.7%). There was lower Asian representation in European (18.1%) and North American-based journals (19.9%) compared to Asian-based journals (72.3%). Females were underrepresented in interventional (14.5%) journals, while Asians were underrepresented in general cardiology (18.3%) and heart failure (18.3%) journals. Journals led by female editors-in-chief had significantly higher female representation compared to male-led ones, while journals with Asian editors-in-chief had greater Asian representation compared to non-Asian led ones. CONCLUSION This study highlights the female and Asian ethnic underrepresentation in academic roles in cardiology journal editorial boards. Further analysis is needed for other ethnicities, while the community pushes towards gender-balanced and ethnic diversity across editorial boards.
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Affiliation(s)
- O Z H Lim
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - Y Chen
- Department of Cardiology, First Medical Centre of Chinese People's Liberation Army (PLA) General Hospital, Wanshoulu, 100036 Beijing, China
| | - S Dimmeler
- Institute for Cardiovascular Regeneration, Goethe University, Theodor-Stern-Kai 7 60590 Frankfurt am Main, Germany
| | - A W J Yong
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - H Singh
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - M L E Sim
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - G Kong
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - W H Lim
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - T T Low
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
- Department of Cardiology, National University Heart Centre, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore
| | - D-W Park
- Division of Cardiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, South Korea
| | - N W S Chew
- Department of Cardiology, National University Heart Centre, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore
| | - R Foo
- From the Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
- Department of Cardiology, National University Heart Centre, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore
- Cardiovascular Diseases Translational Research Programme, National University Health Systems, 1E Kent Ridge Rd, Singapore 119228, Singapore
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Khafaga DS, Ibrahim A, El-Kenawy ESM, Abdelhamid AA, Karim FK, Mirjalili S, Khodadadi N, Lim WH, Eid MM, Ghoneim ME. An Al-Biruni Earth Radius Optimization-Based Deep Convolutional Neural Network for Classifying Monkeypox Disease. Diagnostics (Basel) 2022; 12:diagnostics12112892. [PMID: 36428952 PMCID: PMC9689640 DOI: 10.3390/diagnostics12112892] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/04/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Human skin diseases have become increasingly prevalent in recent decades, with millions of individuals in developed countries experiencing monkeypox. Such conditions often carry less obvious but no less devastating risks, including increased vulnerability to monkeypox, cancer, and low self-esteem. Due to the low visual resolution of monkeypox disease images, medical specialists with high-level tools are typically required for a proper diagnosis. The manual diagnosis of monkeypox disease is subjective, time-consuming, and labor-intensive. Therefore, it is necessary to create a computer-aided approach for the automated diagnosis of monkeypox disease. Most research articles on monkeypox disease relied on convolutional neural networks (CNNs) and using classical loss functions, allowing them to pick up discriminative elements in monkeypox images. To enhance this, a novel framework using Al-Biruni Earth radius (BER) optimization-based stochastic fractal search (BERSFS) is proposed to fine-tune the deep CNN layers for classifying monkeypox disease from images. As a first step in the proposed approach, we use deep CNN-based models to learn the embedding of input images in Euclidean space. In the second step, we use an optimized classification model based on the triplet loss function to calculate the distance between pairs of images in Euclidean space and learn features that may be used to distinguish between different cases, including monkeypox cases. The proposed approach uses images of human skin diseases obtained from an African hospital. The experimental results of the study demonstrate the proposed framework's efficacy, as it outperforms numerous examples of prior research on skin disease problems. On the other hand, statistical experiments with Wilcoxon and analysis of variance (ANOVA) tests are conducted to evaluate the proposed approach in terms of effectiveness and stability. The recorded results confirm the superiority of the proposed method when compared with other optimization algorithms and machine learning models.
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Affiliation(s)
- Doaa Sami Khafaga
- Department of Computer Sciences, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia
- Correspondence: (D.S.K.); (E.-S.M.E.-K.); (A.A.A.); (F.K.K.)
| | - Abdelhameed Ibrahim
- Computer Engineering and Control Systems Department, Faculty of Engineering, Mansoura University, Mansoura 35516, Egypt
| | - El-Sayed M. El-Kenawy
- Department of Communications and Electronics, Delta Higher Institute of Engineering and Technology, Mansoura 35111, Egypt
- Correspondence: (D.S.K.); (E.-S.M.E.-K.); (A.A.A.); (F.K.K.)
| | - Abdelaziz A. Abdelhamid
- Department of Computer Science, College of Computing and Information Technology, Shaqra University, Shaqra 11961, Saudi Arabia
- Department of Computer Science, Faculty of Computer and Information Sciences, Ain Shams University, Cairo 11566, Egypt
- Correspondence: (D.S.K.); (E.-S.M.E.-K.); (A.A.A.); (F.K.K.)
| | - Faten Khalid Karim
- Department of Computer Sciences, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia
- Correspondence: (D.S.K.); (E.-S.M.E.-K.); (A.A.A.); (F.K.K.)
| | - Seyedali Mirjalili
- Centre for Artificial Intelligence Research and Optimization, Torrens University Australia, Fortitude Valley, QLD 4006, Australia
- Yonsei Frontier Lab, Yonsei University, Seoul 03722, Republic of Korea
| | - Nima Khodadadi
- Department of Civil and Environmental Engineering, Florida International University, Miami, FL 33199, USA
| | - Wei Hong Lim
- Faculty of Engineering, Technology and Built Environment, UCSI University, Kuala Lumpur 56000, Malaysia
| | - Marwa M. Eid
- Faculty of Artificial Intelligence, Delta University for Science and Technology, Mansoura 35712, Egypt
| | - Mohamed E. Ghoneim
- Department of Mathematical Sciences, Faculty of Applied Science, Umm Al-Qura University, Makkah 21955, Saudi Arabia
- Faculty of Computers and Artificial Intelligence, Damietta University, Damietta 34511, Egypt
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8
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Chew N, Ng CH, Kong G, Chin YH, Lim O, Lim WH, Dalakoti M, Khoo CM, Kong W, Poh KK, Foo R, Lee CH, Chan MY, Muthiah M, Loh PH. Metabolic associated fatty liver disease increases risk of adverse events after acute coronary syndrome. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.1414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Metabolic Associated Fatty Liver Disease (MAFLD) was recently introduced as an alternative definition for fatty liver, that has been linked to an increased risk of systemic end-organ damage. However, current studies have not examined the impact of MAFLD on patients presenting with acute coronary syndrome (ACS). Here, we present a retrospective analysis on the short and long-term outcomes of ACS patients with MAFLD.
Methods
A retrospective analysis was conducted in a tertiary care centre. Hepatic steatosis and fibrosis was examined with hepatic steatosis index and fibrosis-4 (FIB-4) index. The primary and secondary outcomes of the analysis were long term all-cause mortality, and in-hospital all-cause mortality, stroke, heart failure and cardiogenic shock respectively. Adjusted analysis was conducted for primary and secondary outcomes with covariates including age, sex, race, type of ACS and previous myocardial infarction.
Results
A total of 5770 patients were included in the analysis, and 21% of ACS patients had concomitant MAFLD. MAFLD resulted in a 23% increase in long-term all-cause mortality compared to non-MAFLD (HR: 1.230, CI: 1.065 to 1.420, p=0.005). MAFLD increased the risk of in-hospital mortality, stroke, heart failure and cardiogenic shock compared to non-MAFLD. A sensitivity analysis conducted based on MAFLD with advance fibrosis, chronic kidney disease and diabetes also demonstrated significantly increased effect size magnitude of all-cause mortality, compared to non-MAFLD.
Conclusion
MAFLD represents an encapsulation of metabolism dysregulation and has been associated with increased risk of systematic disease. The present study shows that MAFLD is associated with significantly increased adverse prognostic outcomes after ACS compared to non-MAFLD. An increase in awareness of MAFLD is required beyond the field of hepatology for improvements in multidisciplinary care and management.
Funding Acknowledgement
Type of funding sources: None.
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Affiliation(s)
- N Chew
- National University Heart Centre , Singapore , Singapore
| | - C H Ng
- National University Health System , Singapore , Singapore
| | - G Kong
- National University Health System , Singapore , Singapore
| | - Y H Chin
- National University Health System , Singapore , Singapore
| | - O Lim
- National University of Singapore , Singapore , Singapore
| | - W H Lim
- National University of Singapore , Singapore , Singapore
| | - M Dalakoti
- National University of Singapore , Singapore , Singapore
| | - C M Khoo
- National University Health System , Singapore , Singapore
| | - W Kong
- National University Heart Centre , Singapore , Singapore
| | - K K Poh
- National University Heart Centre , Singapore , Singapore
| | - R Foo
- National University Heart Centre , Singapore , Singapore
| | - C H Lee
- National University Heart Centre , Singapore , Singapore
| | - M Y Chan
- National University Heart Centre , Singapore , Singapore
| | - M Muthiah
- National University Health System , Singapore , Singapore
| | - P H Loh
- National University Heart Centre , Singapore , Singapore
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9
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Chew NWS, Ng CH, Kong G, Tan D, Lim WH, Kofidis T, Yip J, Loh PH, Chan KH, Low A, Lee CH, Yeo TC, Tan HC, Chan MY. Reconstructed meta-analysis of percutaneous coronary intervention versus coronary artery bypass grafting for left main disease. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.1415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Randomized controlled trials (RCTs) comparing percutaneous coronary intervention (PCI) with drug-eluting stents and coronary artery bypass grafting (CABG) for patients with left main coronary artery disease (LMCAD) have reported conflicting results.
Objectives
We performed a systematic review from inception to 23 May 2021 and one-stage reconstructed individual-patient data meta-analysis (IPDMA) that included 10-year mortality outcomes.
Methods
The primary outcome was 10-year all-cause mortality. Secondary outcomes included myocardial infarction (MI), stroke and unplanned revascularization at 5 years. We did IPDMA using published Kaplan-Meier curves to provide individual data points in coordinates and numbers at risk were used to increase the calibration accuracy of the reconstructed data. Shared frailty model or, when proportionality assumptions were not met, a restricted mean survival time model were fitted to compare outcomes between treatment groups.
Results
Of 583 articles retrieved, 5 RCTs were included. A total of 4595 patients from these 5 RCTs were randomly assigned to PCI (N=2297) or CABG (N=2298). The cumulative 10-year all-cause mortality after PCI and CABG was 12.0% versus 10.6% respectively (HR 1.093, 95% CI: 0.925–1.292; p=0.296). PCI conferred similar time-to-MI (RMST ratio 1.006, 95% CI: 0.992–1.021, p=0.391) and stroke (RMST ratio 1.005, 95% CI: 0.998–1.013, p=0.133) at 5 years. Unplanned revascularization was more frequent following PCI compared with CABG (HR 1.807, 95% CI: 1.524–2.144, p<0.001) at 5 years.
Conclusion
This meta-analysis using reconstructed participant-level time-to-event data showed no statistically significant difference in cumulative 10-year all-cause mortality between PCI versus CABG in the treatment of LMCAD.
Funding Acknowledgement
Type of funding sources: None.
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Affiliation(s)
- N W S Chew
- National University Heart Centre , Singapore , Singapore
| | - C H Ng
- National University of Singapore , Singapore , Singapore
| | - G Kong
- National University of Singapore , Singapore , Singapore
| | - D Tan
- National University of Singapore , Singapore , Singapore
| | - W H Lim
- National University of Singapore , Singapore , Singapore
| | - T Kofidis
- National University Heart Centre , Singapore , Singapore
| | - J Yip
- National University Heart Centre , Singapore , Singapore
| | - P H Loh
- National University Heart Centre , Singapore , Singapore
| | - K H Chan
- National University Heart Centre , Singapore , Singapore
| | - A Low
- National University Heart Centre , Singapore , Singapore
| | - C H Lee
- National University Heart Centre , Singapore , Singapore
| | - T C Yeo
- National University Heart Centre , Singapore , Singapore
| | - H C Tan
- National University Heart Centre , Singapore , Singapore
| | - M Y Chan
- National University Heart Centre , Singapore , Singapore
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10
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Gebre AK, Prince RL, Schousboe JT, Kiel DP, Thompson PL, Zhu K, Lim WH, Sim M, Lewis JR. Calcaneal quantitative ultrasound is associated with all-cause and cardiovascular disease mortality independent of hip bone mineral density. Osteoporos Int 2022; 33:1557-1567. [PMID: 35147712 PMCID: PMC9187548 DOI: 10.1007/s00198-022-06317-x] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 01/20/2022] [Indexed: 11/26/2022]
Abstract
UNLABELLED Osteoporosis has been linked with increased risk of cardiovascular disease previously. However, few studies have detailed bone and vascular information. In a prospective study of older women, we demonstrated heel quantitative ultrasound measures were associated with increased cardiovascular and all-cause mortality, independent of established cardiovascular risk factors. INTRODUCTION Osteoporosis and low bone mineral density (BMD) have been previously linked to cardiovascular disease (CVD) and mortality. Calcaneal quantitative ultrasound (QUS) is used to evaluate bone material properties, especially in older women. However, it is uncertain whether it is related to risk of mortality. This study was aimed to investigate the association between calcaneal QUS measurements and 15-year all-cause and CVD mortality in 1404 older women (mean age 75.2 ± 2.7 years). METHODS One thousand four hundred four older women, participants of Calcium Intake Fracture Outcome study (CAIFOS), had calcaneal bone measured at baseline (1998) and followed for 15 years. The primary outcomes, any deaths, and deaths attributable to cardiovascular causes ascertained by using linked data were obtained from Western Australia data linkage system. RESULTS Over the 15 years of follow-up (17,955 person years), 584 of the women died, and 223 from CVD. For every standard deviation (SD), reduction in broadband ultrasound attenuation (BUA) in minimally and multivariable-adjusted model including cardiovascular risk factors increased relative hazards for all-cause (multivariable-adjusted HR 1.15; 95%CI: 1.06-1.26, p = 0.001) and CVD mortality (multivariable-adjusted HR 1.20; 95%CI: 1.04-1.38, p = 0.010). Such relationships also persisted when hip BMD was included in the model (all-cause mortality HR 1.19; 95%CI: 1.07-1.33, p = 0.002; CVD mortality HR 1.28; 95%CI: 1.07-1.53, p = 0.008). CONCLUSION BUA is associated with all-cause and CVD mortality in older women independent of BMD and established CVD risk factors. Understanding why and how these are related may provide further insights about the bone-vascular nexus as well as therapeutic targets benefiting both systems.
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Affiliation(s)
- A K Gebre
- Institute for Nutrition Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, 6027, Australia
- School of Pharmacy, College of Health Sciences, Mekelle University, Mekelle, Ethiopia
| | - R L Prince
- Medical School, The University of Western Australia, Perth, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia
| | - J T Schousboe
- Park Nicollet Osteoporosis Center and HealthPartners Institute, HealthPartners, Minneapolis, MN, 55416, USA
- Division of Health Policy and Management, University of Minnesota, Minneapolis, MN, 55455, USA
| | - D P Kiel
- Marcus Institute for Aging Research, Hebrew SeniorLife, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, 02215, USA
| | - P L Thompson
- Medical School, The University of Western Australia, Perth, Australia
- Department of Cardiology, Sir Charles Gairdner Hospital, Perth, Australia
| | - K Zhu
- Medical School, The University of Western Australia, Perth, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia
| | - W H Lim
- Medical School, The University of Western Australia, Perth, Australia
- Renal Department, Sir Charles Gairdner Hospital, Perth, Australia
| | - M Sim
- Institute for Nutrition Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, 6027, Australia
- Medical School, The University of Western Australia, Perth, Australia
| | - J R Lewis
- Institute for Nutrition Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, 6027, Australia.
- Medical School, The University of Western Australia, Perth, Australia.
- Centre for Kidney Research, Children's Hospital at Westmead School of Public Health, Sydney Medical School, The University of Sydney, Sydney, Australia.
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11
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Krishnan A, Wong G, Teixeira-Pinto A, Lim WH. Incidence and Outcomes of Early Cancers After Kidney Transplantation. Transpl Int 2022; 35:10024. [PMID: 35592449 PMCID: PMC9110645 DOI: 10.3389/ti.2022.10024] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 04/05/2022] [Indexed: 11/13/2022]
Abstract
Outcomes of early cancers after kidney transplantation are not well-understood. We included recipients of first live and deceased donor kidney transplants who developed de novo cancers in Australia and New Zealand between 1980–2016. We compared the frequency and stage of specific cancer types that developed early (≤12-months) and late (>12-months) post-transplantation. Risk factors for death were evaluated using multivariable Cox regression analyses. Of 2,759 recipients who developed de novo cancer, followed-up for 40,035 person-years, 243 (8.8%) patients were diagnosed with early cancer. Post-transplant lymphoproliferative disease, urinary cancers and melanoma were the most common cancer types (26%, 18%, and 12%) and the majority were either in-situ or locally invasive lesions (55%, 84%, and 86%). Tumors arising early from the gastrointestinal and respiratory systems were uncommon but aggressive, with 40% presenting with metastatic disease at time of diagnosis. Overall, 32% of patients with early cancers died within a median of 4.7 months (IQR:0.6–16) post-diagnosis and 91% were cancer-related deaths. Older recipient and donor age were associated with an increased risk of all-cause death. Early cancers, though infrequent in kidney transplant recipients, are associated with poor outcomes, as nearly 1 in 3 died from cancer-related death; with majority of deaths occurring within 12-months of cancer diagnosis.
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Affiliation(s)
- A Krishnan
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, WA, Australia.,Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia
| | - G Wong
- Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia.,Centre for Transplant and Renal Research, Westmead Hospital, Sydney, NSW, Australia.,Centre for Kidney Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - A Teixeira-Pinto
- Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia
| | - W H Lim
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, WA, Australia.,School of Medicine, University of Western Australia, Perth, WA, Australia
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12
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Misal M, Behbehani S, Bindra V, Girardo M, Hoffman MR, Lim WH, Martin CB, Mehta SK, Nensi A, Soares TR, Taylor D, Wagner S, Wright KN, Wasson MN. Evaluating Surgical Complexity of Endoscopic Hysterectomy: An Inter-Rater Agreement Study for Novel Scoring Tool. J Minim Invasive Gynecol 2021. [DOI: 10.1016/j.jmig.2021.09.453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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13
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Chew N, Tan EX, Tan CH, Lim WH, Xiao JL, Chin YH, Syn N, Low TT, Wong R, Yip J, Siddiqui MS, Muthiah M. A network meta-analysis on the vasomodulators for portopulmonary hypertension. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.1956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
In patients with portopulmonary hypertension (PoPH) who are eligible and awaiting liver transplant, guidelines recommend lowering pulmonary pressures with vasomodulators as a bridge to transplant. However, efficacy of each vasomodulator class as a bridge to transplant remains unknown.
Purpose
This review compares the use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 inhibitors (PDE5-I), prostacyclin (PC) and combination therapy in its pulmonary pressure-lowering effects and pre-transplant mortality in this strictly selected subset of patients.
Methods
A search conducted on Medline and Embase on articles relating to vasomodulator use in PoPH for pulmonary pressure-lowering effects and mortality. Network analysis was conducted to summarize the evidence. Surface under the cumulative ranking curve (SUCRA) was used to rank treatments.
Results
Ten studies with 180 patients were included. SUCRA analysis demonstrated largest mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) lowering effects in ERA and combination therapy, followed by PDE5-I and PC. mPAP-lowering effects were largest in ERA (MD −19.440, CI: −62.280 to 23.400) and combination therapy (MD −18.223, CI: −29.677 to −6.770) when compared to PDE5-I (table 1). Pre-transplant mortality were comparable between ERA, PDE5-I and combination therapy. Both ERA (RR:0.349. CI: 0.137–0.891) and PDE5-I (RR: 0.279, CI: 0.091–0.854) had significantly lower mortality than PC (table 2).
Conclusion
This meta-analysis provides preliminary evidence that ERA have shown larger pulmonary pressure-lowering effects than PDE5-I in PoPH patients who were eligible for LT. Both ERA and PDE5-I have comparable mortality outcomes, with unfavorable outcomes in PC users.
Funding Acknowledgement
Type of funding sources: None.
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Affiliation(s)
- N Chew
- National University Health System, Singapore, Singapore
| | - E X Tan
- National University Hospital, Division of Gastroenterology and Hepatology, Singapore, Singapore
| | - C H Tan
- National University of Singapore, Singapore, Singapore
| | - W H Lim
- National University of Singapore, Singapore, Singapore
| | - J L Xiao
- National University of Singapore, Singapore, Singapore
| | - Y H Chin
- National University of Singapore, Singapore, Singapore
| | - N Syn
- National University of Singapore, Singapore, Singapore
| | - T T Low
- National University Heart Centre, Singapore, Singapore
| | - R Wong
- National University Heart Centre, Singapore, Singapore
| | - J Yip
- National University Heart Centre, Singapore, Singapore
| | - M S Siddiqui
- Virginia Commonwealth University, Division of Gastroenterology and Hepatology, Richmond, United States of America
| | - M Muthiah
- National University Hospital, Division of Gastroenterology and Hepatology, Singapore, Singapore
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14
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Tan SH, Pui LP, Solihin MI, Keat KS, Lim WH, Ang CK. Physicochemical analysis and adulteration detection in Malaysia stingless bee honey using a handheld near‐infrared spectrometer. J FOOD PROCESS PRES 2021. [DOI: 10.1111/jfpp.15576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shi Hui Tan
- Food Science with Nutrition Department, Faculty of Applied Sciences UCSI University Kuala Lumpur Malaysia
| | - Liew Phing Pui
- Food Science with Nutrition Department, Faculty of Applied Sciences UCSI University Kuala Lumpur Malaysia
| | - Mahmud Iwan Solihin
- Mechanical and Mechatronics Engineering Department, Faculty of Engineering UCSI University Kuala Lumpur Malaysia
| | - Kong Seah Keat
- Mechanical and Mechatronics Engineering Department, Faculty of Engineering UCSI University Kuala Lumpur Malaysia
| | - Wei Hong Lim
- Mechanical and Mechatronics Engineering Department, Faculty of Engineering UCSI University Kuala Lumpur Malaysia
| | - Chun Kit Ang
- Mechanical and Mechatronics Engineering Department, Faculty of Engineering UCSI University Kuala Lumpur Malaysia
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15
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Wong C, Lim WH, Jain SR, Ng CH, Tai CH, Devi MK, Samarasekera DD, Iyer SG, Chong CS. 46 The Hidden Truth About Gender Bias in Surgery. A Systematic Review. Br J Surg 2021. [DOI: 10.1093/bjs/znab134.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Introduction
Gender discrimination remains pervasive in surgery, significantly impacting current and future surgeons and population health. This study analyses the gender barriers and critical retention factors for female surgeons and trainees in surgery.
Method
Five electronic databases were searched till May 2020. Titles and abstracts were sieved, followed by a full text review. Data synthesis and inductive thematic analysis were conducted using the Thomas and Harden methodology.
Result
14 articles were included, involving 528 participants. Four themes were generated–unfavourable working environment, male-dominated culture, societal pressures and progress towards gender equality. Females in surgery often faced harassment, disrespect and perceptions of incompetence, resulting in hostile work conditions, which were aggravated by the inadequate support and mentorship. The persistence of male-dominated cultures was observed, with females facing prejudice and exclusion from professional and social circles. Differential treatment and higher expectations of female surgeons also arose from entrenched societal pressures. Despite these, increased acceptance of motherhood and greater recognition of contributions by female surgeons were reported, indicating some progress in gendered culture.
Conclusions
There is a need to increase female surgical leadership and allocate resources to address the deep-rooted causes of biased surgical culture and ingrained perceptions, to achieve greater gender equality in surgery.
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Affiliation(s)
- C Wong
- Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
| | - W H Lim
- Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
| | - S R Jain
- Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
| | - C H Ng
- Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
| | - C H Tai
- Division of Colorectal Surgery, Department of Surgery, University Surgical Cluster, National University Hospital, Singapore, Singapore
| | - M K Devi
- Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - D D Samarasekera
- Centre for Medical Education, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - S G Iyer
- Division of Hepatobiliary & Pancreatic Surgery, Department of Surgery, University Surgical Cluster, National University Hospital, Singapore, Singapore
- Liver Transplantation, National University Centre for Organ Transplantation, National University Hospital, Singapore, Singapore
| | - C S Chong
- Division of Colorectal Surgery, Department of Surgery, University Surgical Cluster, National University Hospital, Singapore, Singapore
- Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
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16
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Ng CH, Jain SR, Ow ZGW, Lim WH, Tham HY, Wong NW, Chong CS, Foo FJ. 20 Post-Operative Biologics and the Rate of Recurrence in Crohn’s Disease. Br J Surg 2021. [DOI: 10.1093/bjs/znab134.189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Introduction
Post-operative recurrence after Crohn’s surgery poses a significant challenge to clinicians with an estimated of 70-90% recurrence rate. However, with the advent of biologics, reduction of recurrence after surgery has been observed in various landmark trials. Hence, we aim to quantify the rate of recurrence with post-operative biologics.
Method
Searches were done on Embase and Medline database for articles using biologics for post-operative management. A single arm meta-analysis with generalized linear mixed model and Clopper-Pearson method confidence interval was applied in the synthesis of the data on six months, one year, two year and five year.
Results
A total of 1,864 abstracts were identified, with a final total of 24 articles and 1042 patients were included in the meta-analysis. The one-year rate of recurrence for surgical, endoscopic and clinical was 3.08% (CI: 0.74% - 11.95%), 19.93% (15.81% - 24.81%) and 13.06% (CI: 8.18% - 18.92%) respectively. Correspondingly, the five-year recurrence 16.90% (CI: 9.57% - 28.11%), 84.21% (CI: 72.35% - 91.57%), 5.60% (CI: 9.92% -23.66%) respectively.
Conclusions
An observed reduction in surgical rates was reduced at five years with post-operative Crohn’s disease with biologics. Biologics therapy thus can be considered as a suitable alternative for reducing post-operative recurrence in individuals with higher risk.
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Affiliation(s)
- C H Ng
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - S R Jain
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Z G W Ow
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - W H Lim
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - H Y Tham
- National University Hospital, Singapore, Singapore
| | - N W Wong
- National University Hospital, Singapore, Singapore
| | - C S Chong
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - F J Foo
- Sengkang General Hospital, Singapore, Singapore
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17
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Tay PWL, Xiao JL, Lim WH, Wong NW, Chong CS. 207 Laparoscopic versus Open Surgery for Locally Advanced Colon Cancer: A Retrospective Cohort Study. Br J Surg 2021. [DOI: 10.1093/bjs/znab134.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Introduction
While an increasing number of studies substantiate the non-inferiority of laparoscopy to open surgery for pT4 colon cancer, studies investigating its value specific to the subgroup pT4a in right hemicolectomies remain scarce.
Method
We performed a retrospective cohort analysis in National University Hospital of Singapore of patients who underwent a right hemicolectomy for pT4 colon cancer. Statistical analysis was performed using Wilcoxon rank sum test and chi square/fisher exact.
Results
In total, 65 patients had T4 colon cancer. 55 underwent right hemicolectomy and 10 underwent extended right hemicolectomy. Baseline demographics were similar in laparoscopic (n = 27) and open (n = 38) groups, with no significant difference in proportion of pT4a patients (p = 0.724). For pT4, 30-day mortality (7%, 5% respectively, p = 0.723), overall survival (p = 0.1903) and disease-free survival (p = 0.3476) did not differ significantly between laparoscopic and open groups. R0 resection rates were significantly higher in laparoscopic group (p = 0.039). pT4a subgroup analysis found similar observations. Other complications including postoperative wound infection and anastomotic bleed were not significantly different for both T4 and T4a analysis.
Conclusions
This study presented comparable safety and oncological outcomes between the two surgical methods for right hemicolectomy, suggesting laparoscopy to be a viable alternative approach for locally advanced right colon cancer.
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Affiliation(s)
- P W L Tay
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - J L Xiao
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - W H Lim
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - N W Wong
- Division of Colorectal Surgery, Department of Surgery, National University Hospital, Singapore, Singapore, Singapore
| | - C S Chong
- Division of Colorectal Surgery, Department of Surgery, National University Hospital, Singapore, Singapore, Singapore
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18
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Ng CH, Chin YH, Nistala KRY, Jain SR, Ow ZGW, Wong NW, Tham HY, Lim WH, Chong CS. 189 Preliminary Results from an Innovative Surgical Research Group for Medical Students. Br J Surg 2021. [DOI: 10.1093/bjs/znab134.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Introduction
Learning research in medical school can be daunting and difficult with many lacking appropriate guidance. Particularly, research in surgery can be difficult with most clinicians tied to long hours from clinical duties, leaving medical students lost to learn the ropes for medical research.
Method
We started a surgical research group in January of 2020 under a shepherd sheep model. Shepards were senior medical students who had previous experience in research and were provided resources from consultants on statistics and research designs. Thereafter, each Shepard were paired with junior medical students (sheep) and a resident to provide clinical background. Research was then carried out small teams with minimal guidance from consultants.
Results
To date, the group has published 11 articles (median impact factor: 2.41, range: 1.89 - 3.42), 3 articles in revision and 9 articles in review.
Conclusions
We provide preliminary evidence of a successful model for building medical student research in surgery. While current analysis was limited to meta-analysis and systematic review due to the availability of data, current expansion is currently underway to expand to observational studies.
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Affiliation(s)
- C H Ng
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Y H Chin
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - K R Y Nistala
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - S R Jain
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - Z G W Ow
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - N W Wong
- National University Hospital, Singapore, Singapore
| | - H Y Tham
- National University Hospital, Singapore, Singapore
| | - W H Lim
- Yong Loo Lin School of Medicine, Singapore, Singapore
| | - C S Chong
- Yong Loo Lin School of Medicine, Singapore, Singapore
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19
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Alrifaey M, Lim WH, Ang CK. A Novel Deep Learning Framework Based RNN-SAE for Fault Detection of Electrical Gas Generator. IEEE Access 2021; 9:21433-21442. [DOI: 10.1109/access.2021.3055427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
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20
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Kim M, Kim HL, Park KT, Lim WH, Seo JB, Kim SH, Kim MA, Zo JH. P1348 Impact of left ventricular ejection fraction and aortic valve sclerosis on cardiovascular outcome in patients with acute ischemic stroke. Eur Heart J Cardiovasc Imaging 2020. [DOI: 10.1093/ehjci/jez319.784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background/Introduction
Previous studies have focused on only 1 or 2 echocardiographic parameters as prognostic marker in patients with acute ischemic stroke (AIS).
Purpose
Various echocardiographic parameters in the same patient were systemically evaluated for their prognostic significance in AIS.
Methods
A total of 900 patients with AIS who underwent transthoracic echocardiography (TTE) (72.6 ± 12.0 years and 60% male) were retrospectively reviewed. Composite events including all-cause mortality, non-fatal stroke, non-fatal myocardial infarction, and coronary revascularization were assessed during clinical follow-up.
Results
During a median follow-up of 3.3 years (interquartile range, 0.6-5.1 years), there were 151 (16.8%) composite events. Univariable analyses showed that low left ventricular ejection fraction (LVEF) (< 60%), increased peak tricuspid regurgitation (TR) velocity (> 2.8 m/s) and aortic valve (AV) sclerosis were associated with composite events (P < 0.05 for each). In the multivariable analyses after controlling for potential confounders, LVEF < 60% (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.30-2.77; P = 0.001) and AV sclerosis (HR, 1.56; 95% CI, 1.10-2.21; P = 0.013) were independent prognostic factors associated with composite events. Multivariable analysis showed that HR for composite events gradually increased according to LVEF and AV sclerosis: HR was 2.8-fold higher in the highest-risk group than in the lowest group (P = 0.001).
Conclusions
In patients with AIS, LVEF < 60% and the presence of AV sclerosis predicts the future vascular events. Patients with AIS exhibiting reduced LVEF and AV sclerosis may benefit from aggressive secondary prevention
Abstract P1348 Figure. COX plot for composite event
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Affiliation(s)
- M Kim
- Boramae Hospital, Seoul, Korea (Republic of)
| | - H L Kim
- Boramae Hospital, Seoul, Korea (Republic of)
| | - K T Park
- Boramae Hospital, Seoul, Korea (Republic of)
| | - W H Lim
- Boramae Hospital, Seoul, Korea (Republic of)
| | - J B Seo
- Boramae Hospital, Seoul, Korea (Republic of)
| | - S H Kim
- Boramae Hospital, Seoul, Korea (Republic of)
| | - M A Kim
- Boramae Hospital, Seoul, Korea (Republic of)
| | - J H Zo
- Boramae Hospital, Seoul, Korea (Republic of)
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21
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Lewis JR, Brennan-Speranza TC, Levinger I, Byrnes E, Lim EM, Blekkenhorst LC, Sim M, Hodgson JM, Zhu K, Lim WH, Adams LA, Prince RL. Effects of calcium supplementation on circulating osteocalcin and glycated haemoglobin in older women. Osteoporos Int 2019; 30:2065-2072. [PMID: 31342138 DOI: 10.1007/s00198-019-05087-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/09/2019] [Indexed: 01/18/2023]
Abstract
UNLABELLED One year of calcium supplementation in older women led to modest reductions in total osteocalcin and undercarboxylated osteocalcin (ucOC), with no changes in muscle or fat mass, or glycated haemoglobin. Future studies should explore whether treatments with more profound effects of suppressing ucOC may lead to impaired glycaemic control. INTRODUCTION Total osteocalcin (TOC) is a marker of bone turnover, while its undercarboxylated form has beneficial effects on glucose metabolism in mice. This post hoc analysis of a randomised double-blind, placebo-controlled trial examined whether 1 year of calcium supplementation affected circulating TOC, undercarboxylated osteocalcin (ucOC) or glycated haemoglobin (HbA1c) in 1368 older community-dwelling women (mean age 75.2 ± 2.7 years). METHODS Women enrolled in the Calcium Intake Fracture Outcome Study trial (1998-2003) were supplemented with 1.2 g/d of elemental calcium (in the form of calcium carbonate) or placebo. Circulating TOC, ucOC and HbA1c was measured at 1 year (1999). RESULTS After 1 year of calcium supplementation, TOC and ucOC levels were 17% and 22% lower compared with placebo (mean 22.7 ± 9.1 vs. 27.3 ± 10.9 μg/L and 11.1 ± 4.9 vs. 13.0 ± 5.7 μg/L, both P < 0.001). Carboxylated osteocalcin/ucOC was 6% lower after calcium supplementation (P < 0.05). Despite this, no differences in HbA1c were observed (calcium, 5.2 ± 0.6 vs. placebo, 5.3 ± 0.8%; P = 0.08). Calcium supplementation did not affect BMI, whole body lean or fat mass. In exploratory analyses, total calcium (dietary and supplemental) was inversely related to TOC and ucOC, indicating calcium intake is an important dietary determinant of osteocalcin levels. CONCLUSION One year of calcium supplementation in older women led to modest reductions in TOC and ucOC, with no changes in muscle or fat mass, or HbA1c. Future studies should explore whether treatments with more profound effects of suppressing ucOC may lead to impaired glycaemic control.
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Affiliation(s)
- J R Lewis
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia.
- Medical School, University of Western Australia, Perth, Australia.
- Centre for Kidney Research, Children's Hospital at Westmead School of Public Health, Sydney Medical School, The University of Sydney, Sydney, Australia.
| | - T C Brennan-Speranza
- Department of Physiology, Bosch Institute for Medical Research, University of Sydney, Sydney, Australia
| | - I Levinger
- Institute of Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
- Australian Institute for Musculoskeletal Science (AIMSS), Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia
| | - E Byrnes
- PathWest Laboratory Medicine, Sir Charles Gairdner Hospital, Perth, Australia
| | - E M Lim
- PathWest Laboratory Medicine, Sir Charles Gairdner Hospital, Perth, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia
| | - L C Blekkenhorst
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - M Sim
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
- Medical School, University of Western Australia, Perth, Australia
| | - J M Hodgson
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
- Medical School, University of Western Australia, Perth, Australia
| | - K Zhu
- Medical School, University of Western Australia, Perth, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia
| | - W H Lim
- Medical School, University of Western Australia, Perth, Australia
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Australia
| | - L A Adams
- Medical School, University of Western Australia, Perth, Australia
- Department of Hepatology, Sir Charles Gairdner Hospital, Nedlands, Australia
| | - R L Prince
- Medical School, University of Western Australia, Perth, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Australia
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Chung JH, Kim HL, Lim WH, Kim MA, Kim SH. P5392Statin intensity and new onset diabetes mellitus in patients undergoing percutaneous coronary intervention with drug-eluting stents. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.p5392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- J H Chung
- National Medical Center, Cardiology, Internal Medicine, Seoul, Korea Republic of
| | - H L Kim
- Boramae Hospital, Internal Medicine, Cardiology, sSeoul, Korea Republic of
| | - W H Lim
- Boramae Hospital, Internal Medicine, Cardiology, sSeoul, Korea Republic of
| | - M A Kim
- Boramae Hospital, Internal Medicine, Cardiology, sSeoul, Korea Republic of
| | - S H Kim
- Boramae Hospital, Internal Medicine, Cardiology, sSeoul, Korea Republic of
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Lim TK, Chee CB, Chow P, Chua GSW, Eng SK, Goh SK, Kng KK, Lim WH, Ng TP, Ong TH, Seah STA, Tan HY, Tee KH, Palanichamy V, Yeung MT. Ministry of Health Clinical Practice Guidelines: Chronic Obstructive Pulmonary Disease. Singapore Med J 2018; 59:76-86. [DOI: 10.11622/smedj.2018015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Nam JG, Kang KM, Choi SH, Lim WH, Yoo RE, Kim JH, Yun TJ, Sohn CH. Comparison between the Prebolus T1 Measurement and the Fixed T1 Value in Dynamic Contrast-Enhanced MR Imaging for the Differentiation of True Progression from Pseudoprogression in Glioblastoma Treated with Concurrent Radiation Therapy and Temozolomide Chemotherapy. AJNR Am J Neuroradiol 2017; 38:2243-2250. [PMID: 29074633 DOI: 10.3174/ajnr.a5417] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [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: 02/23/2017] [Accepted: 07/24/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND PURPOSE Glioblastoma is the most common primary brain malignancy and differentiation of true progression from pseudoprogression is clinically important. Our purpose was to compare the diagnostic performance of dynamic contrast-enhanced pharmacokinetic parameters using the fixed T1 and measured T1 on differentiating true from pseudoprogression of glioblastoma after chemoradiation with temozolomide. MATERIALS AND METHODS This retrospective study included 37 patients with histopathologically confirmed glioblastoma with new enhancing lesions after temozolomide chemoradiation defined as true progression (n = 15) or pseudoprogression (n = 22). Dynamic contrast-enhanced pharmacokinetic parameters, including the volume transfer constant, the rate transfer constant, the blood plasma volume per unit volume, and the extravascular extracellular space per unit volume, were calculated by using both the fixed T1 of 1000 ms and measured T1 by using the multiple flip-angle method. Intra- and interobserver reproducibility was assessed by using the intraclass correlation coefficient. Dynamic contrast-enhanced pharmacokinetic parameters were compared between the 2 groups by using univariate and multivariate analysis. The diagnostic performance was evaluated by receiver operating characteristic analysis and leave-one-out cross validation. RESULTS The intraclass correlation coefficients of all the parameters from both T1 values were fair to excellent (0.689-0.999). The volume transfer constant and rate transfer constant from the fixed T1 were significantly higher in patients with true progression (P = .048 and .010, respectively). Multivariate analysis revealed that the rate transfer constant from the fixed T1 was the only independent variable (OR, 1.77 × 105) and showed substantial diagnostic power on receiver operating characteristic analysis (area under the curve, 0.752; P = .002). The sensitivity and specificity on leave-one-out cross validation were 73.3% (11/15) and 59.1% (13/20), respectively. CONCLUSIONS The dynamic contrast-enhanced parameter of rate transfer constant from the fixed T1 acted as a preferable marker to differentiate true progression from pseudoprogression.
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Affiliation(s)
- J G Nam
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - K M Kang
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - S H Choi
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
- Center for Nanoparticle Research, Institute for Basic Science (S.H.C., C.-H.S.)
- School of Chemical and Biological Engineering (S.H.C.), Seoul National University, Seoul, Korea
| | - W H Lim
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - R-E Yoo
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - J-H Kim
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - T J Yun
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
| | - C-H Sohn
- From the Department of Radiology (J.G.N., K.M.K., S.H.C., W.H.L., R.-E.Y., J.-H.K., T.J.Y., C.-H.S.), Seoul National University Hospital, Seoul, Korea
- Center for Nanoparticle Research, Institute for Basic Science (S.H.C., C.-H.S.)
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Wong G, Au E, Badve SV, Lim WH. Breast Cancer and Transplantation. Am J Transplant 2017; 17:2243-2253. [PMID: 28544474 DOI: 10.1111/ajt.14368] [Citation(s) in RCA: 19] [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: 12/13/2016] [Revised: 04/12/2017] [Accepted: 05/04/2017] [Indexed: 01/25/2023]
Abstract
Breast cancer is an important cancer among solid organ transplant recipients. While the incidence of breast cancer in solid organ transplant recipients is comparable to the age-matched general population, the outcomes are generally poor. Interventions such as cancer screening that preclude the development of late-stage disease through early detection are not well studied, and clinical practice guidelines for cancer screening rely solely on recommendations from the general population. Among patients with a prior breast cancer history, disease recurrence after transplantation is a rare but fearful event. Once disease recurs, the risk of death is high. The focus of this review is to present the epidemiology of breast cancer in solid organ transplant recipients, screening and preventive strategies for those who may be at risk, novel genomic profiling for determining tumor progression, and the newer targeted interventions for recipients who have developed breast cancers after solid organ transplantation.
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Affiliation(s)
- G Wong
- Centre for Transplant and Renal Research, Westmead Hospital, Westmead, NSW, Australia.,Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia
| | - E Au
- Centre for Transplant and Renal Research, Westmead Hospital, Westmead, NSW, Australia
| | - S V Badve
- Department of Renal Medicine, St George Hospital, Sydney, NSW, Australia
| | - W H Lim
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
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Krishnan AR, Wong G, Chapman JR, Coates PT, Russ GR, Pleass H, Russell C, He B, Lim WH. Prolonged Ischemic Time, Delayed Graft Function, and Graft and Patient Outcomes in Live Donor Kidney Transplant Recipients. Am J Transplant 2016; 16:2714-23. [PMID: 27037866 DOI: 10.1111/ajt.13817] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [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: 09/13/2015] [Revised: 02/22/2016] [Accepted: 03/24/2016] [Indexed: 01/25/2023]
Abstract
The association between prolonged cold ischemic time (CIT) and graft and patient outcomes in live donor kidney transplant recipients remains unclear. The aims of this study were to examine the association of CIT with delayed graft function and graft loss in live donor kidney transplant recipients and those who participated in the Australian Paired Kidney Exchange program using data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry. Of 3717 live donor transplant recipients between 1997 and 2012 who were followed for a median of 6.6 years (25 977 person-years), 224 (25%) experienced CIT >4-8 h. Donor age was an effect modifier between CIT and graft outcomes. In recipients who received kidneys from older donors aged >50 years, every hour of increase in CIT was associated with adjusted odds of 1.28 (95% confidence interval [CI] 1.07-1.53, p = 0.007) for delayed graft function, whereas CIT >4-8 h was associated with adjusted hazards of 1.93 (95% CI 1.21-3.09, p = 0.006) and 1.91 (95% CI 1.05-3.49, p = 0.035) for overall and death-censored graft loss, respectively, compared with CIT of 1-2 h. Attempts to reduce CIT in live donor kidney transplants involving older donor kidneys may lead to improvement of graft outcomes.
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Affiliation(s)
- A R Krishnan
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia
| | - G Wong
- Australia and New Zealand Dialysis and Transplant Registry, South Australia, Australia.,Centre for Transplant and Renal Research, Westmead Hospital, New South Wales, Australia.,Centre for Kidney Research, The Children's Hospital at Westmead, New South Wales, Australia.,Sydney School of Public Health, University of Sydney, New South Wales, Australia
| | - J R Chapman
- Centre for Transplant and Renal Research, Westmead Hospital, New South Wales, Australia
| | - P T Coates
- Central and Northern Adelaide Renal and Transplantation Services, South Australia, Australia
| | - G R Russ
- Australia and New Zealand Dialysis and Transplant Registry, South Australia, Australia.,Central and Northern Adelaide Renal and Transplantation Services, South Australia, Australia
| | - H Pleass
- Centre for Transplant and Renal Research, Westmead Hospital, New South Wales, Australia
| | - C Russell
- Central and Northern Adelaide Renal and Transplantation Services, South Australia, Australia
| | - B He
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia
| | - W H Lim
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Western Australia, Australia.,Australia and New Zealand Dialysis and Transplant Registry, South Australia, Australia
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Chong WY, Lim WH, Yap YK, Lai CK, De La Rue RM, Ahmad H. Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation. Sci Rep 2016; 6:23813. [PMID: 27034015 PMCID: PMC4817118 DOI: 10.1038/srep23813] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 03/15/2016] [Indexed: 11/24/2022] Open
Abstract
Increased absorption of transverse-magnetic (TM) - polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE) - polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light - and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light).
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Affiliation(s)
- W Y Chong
- Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - W H Lim
- Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Y K Yap
- Heriot-Watt University Malaysia, Putrajaya, 62200 Federal Territory, Malaysia
| | - C K Lai
- Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - R M De La Rue
- Optoelectronics Research Group, School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - H Ahmad
- Photonics Research Centre, Physics Department, Science Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia
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Yin X, Li J, Salmon B, Huang L, Lim WH, Liu B, Hunter DJ, Ransom RC, Singh G, Gillette M, Zou S, Helms JA. Wnt Signaling and Its Contribution to Craniofacial Tissue Homeostasis. J Dent Res 2015; 94:1487-94. [PMID: 26285808 DOI: 10.1177/0022034515599772] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A new field of dental medicine seeks to exploit nature's solution for repairing damaged tissues, through the process of regeneration. Most adult mammalian tissues have limited regenerative capacities, but in lower vertebrates, the molecular machinery for regeneration is an elemental part of their genetic makeup. Accumulating data suggest that the molecular pathways responsible for the regenerative capacity of teleosts, amphibians, and reptiles have fallen into disuse in mammals but that they can be "jumpstarted" by the selective activation of key molecules. The Wnt family of secreted proteins constitutes one such critical pathway: Wnt proteins rank among the most potent and ubiquitous stem cell self-renewing factors, with tremendous potential for promoting human tissue regeneration. Wnt reporter and lineage-tracing strains of mice have been employed to create molecular maps of Wnt responsiveness in the craniofacial tissues, and these patterns of Wnt signaling colocalize with stem/progenitor populations in the rodent incisor apex, the dental pulp, the alveolar bone, the periodontal ligament, the cementum, and oral mucosa. The importance of Wnt signaling in both the maintenance and healing of these craniofacial tissues is summarized, and the therapeutic potential of Wnt-based strategies to accelerate healing through activation of endogenous stem cells is highlighted.
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Affiliation(s)
- X Yin
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - J Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - B Salmon
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA Dental School, University Paris Descartes PRES Sorbonne Paris Cite, Montrouge, France; and AP-HP Odontology Department Bretonneau, Hopitaux Universitaires Paris Nord Val de Seine, Paris, France
| | - L Huang
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA Orthodontic Department, Stomatology Hospital of Chongqing Medical University; Chongqing Key Laboratory of Oral Disease and Biomedical Sciences; and Chongqing Municipal Key Laboratory, Chongqing, China
| | - W H Lim
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
| | - B Liu
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - D J Hunter
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - R C Ransom
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - G Singh
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - M Gillette
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
| | - S Zou
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - J A Helms
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA
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Lim WH, Eris J, Kanellis J, Pussell B, Wiid Z, Witcombe D, Russ GR. A systematic review of conversion from calcineurin inhibitor to mammalian target of rapamycin inhibitors for maintenance immunosuppression in kidney transplant recipients. Am J Transplant 2014; 14:2106-19. [PMID: 25088685 DOI: 10.1111/ajt.12795] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [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: 12/20/2013] [Revised: 04/23/2014] [Accepted: 04/23/2014] [Indexed: 01/25/2023]
Abstract
This was a systematic review of randomized controlled trials comparing delayed conversion of mammalian target of rapamycin inhibitors (mTORi) for calcineurin inhibitors (CNIs) versus CNI continuation in kidney transplantation. Databases (2000-2012) and conference abstracts (2009-2012) were searched giving a total of 29 trials. Outcomes analyzed included GFR, graft loss, rejection and adverse events and were expressed as weighted mean differences (WMDs) or as risk ratios (RRs). Patients converted to mTORi up to 1 year posttransplant in intention-to-treat analysis had higher GFR compared with those remaining on CNI (WMD 0.28 mL/min/1.73 m(2) , 95% confidence interval [CI] 0.21-0.36; I(2) = 68%, p < 0.001). Stratifying trials by time posttransplant or type of mTORi did not change the overall heterogeneity. For on-treatment population, mTORi was associated with higher GFR (14.21 mL/min/1.73 m(2) , 10.34-18.08; I(2) = 0%, p = 0.970) 2-5 years posttransplant. The risk of rejection at 1 year was higher in mTORi trials (RR 1.72, 1.34-2.22; I(2) = 12%, p = 0.330). Discontinuation secondary to adverse events was more common in patients on mTORi, whereas the incidence of skin cancers and cytomegalovirus infection was lower in patients on mTORi. Conversion from CNI to mTORi is associated with short-term improvements in GFR in a number of studies but longer-term follow-up data of graft and patient survival are required.
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Affiliation(s)
- W H Lim
- Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Australia; School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
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Lim WH, Yap YK, Chong WY, Pua CH, Huang NM, De La Rue RM, Ahmad H. Graphene oxide-based waveguide polariser: from thin film to quasi-bulk. Opt Express 2014; 22:11090-11098. [PMID: 24921807 DOI: 10.1364/oe.22.011090] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have demonstrated a broadband waveguide polariser with high extinction ratio on a polymer optical waveguide coated with graphene oxide via the drop-casting method. The highest extinction ratio of nearly 40 dB is measured at 1590 nm, with a variation of 4.5 dB across a wavelength range from 1530 nm to 1630 nm, a ratio that is (to our knowledge) the highest reported for graphene-based waveguide polarisers to date. This result is achieved with a graphene oxide coating length along the propagation direction of only 1.3 mm and a bulk film thickness of 2.0 µm. The underlying principles of the strongly polarisation dependent propagation loss demonstrated have been studied and are attributed to the anisotropic complex dielectric function of graphene oxide bulk film.
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Lim WH, Liu B, Cheng D, Williams BO, Mah SJ, Helms JA. Wnt signaling regulates homeostasis of the periodontal ligament. J Periodontal Res 2014; 49:751-9. [PMID: 24410666 DOI: 10.1111/jre.12158] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2013] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND OBJECTIVE In health, the periodontal ligament maintains a constant width throughout an organism's lifetime. The molecular signals responsible for maintaining homeostatic control over the periodontal ligament are unknown. The purpose of this study was to investigate the role of Wnt signaling in this process by removing an essential chaperone protein, Wntless (Wls), from odontoblasts and cementoblasts, and observing the effects of Wnt depletion on cells of the periodontal complex. MATERIAL AND METHODS The Wnt responsive status of the periodontal complex was assessed using two strains of Wnt reporter mice: Axin2(LacZ/+) and Lgr5(LacZ/+) . The function of this endogenous Wnt signal was evaluated by conditionally eliminating the Wntless (Wls) gene using an osteocalcin Cre driver. The resulting OCN-Cre;Wls (fl/fl) mice were examined using micro-computed tomography and histology, immunohistochemical analyses for osteopontin, Runx2 and fibromodulin, in-situ hybridization for osterix and alkaline phosphatase activity. RESULTS The adult periodontal ligament is Wnt responsive. Elimination of Wnt signaling in the periodontal complex of OCN-Cre;Wls(fl/fl) mice resulted in a wider periodontal ligament space. This pathologically increased periodontal width is caused by a reduction in the expression of osteogenic genes and proteins, which results in thinner alveolar bone. A concomitant increase in fibrous tissue occupying the periodontal space was observed, along with a disruption in the orientation of the periodontal ligament. CONCLUSION The periodontal ligament is a Wnt-dependent tissue. Cells in the periodontal complex are Wnt responsive, and eliminating an essential component of the Wnt signaling network leads to a pathological widening of the periodontal ligament space. Osteogenic stimuli are reduced, and a disorganized fibrillary matrix results from the depletion of Wnt signaling. Collectively, these data underscore the importance of Wnt signaling in homeostasis of the periodontal ligament.
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Affiliation(s)
- W H Lim
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford, CA, USA; Department of Orthodontics, School of Dentistry & Dental Research Institute, Seoul National University, Seoul, Korea
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Lim WH, Lewis JR, Wong G, Dogra GK, Zhu K, Lim EM, Dhaliwal SS, Prince RL. Five-year decline in estimated glomerular filtration rate associated with a higher risk of renal disease and atherosclerotic vascular disease clinical events in elderly women. QJM 2013; 106:443-50. [PMID: 23407347 DOI: 10.1093/qjmed/hct043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Estimated glomerular filtration rate (eGFR) has been demonstrated to predict atherosclerotic vascular disease (ASVD)-associated clinical events independent of traditional vascular risk factors. Recent studies have demonstrated that eGFR decline over time may improve prediction of ASVD-associated mortality risk in chronic kidney disease (CKD) patients. AIM The aim of this study is to evaluate the association between 5-year change in eGFR with renal disease and ASVD-associated clinical events. DESIGN Prospective observational study. METHODS A total of 1012 women over the age of 70 years from the Calcium Intake Fracture Outcome Study were included. Baseline characteristics including baseline and 5-year creatinine, participants' comorbidities and complete verified 10-year records for ASVD and renal disease-associated hospitalization and/or mortality were obtained using the Western Australian Data Linkage System. RESULTS Participants were stratified according to annual rate of eGFR change in quartiles [≤-1.2 (first quartile), >-1.2 to 0.1 (second quartile), >0.1-1.7 (third quartile) and >1.7 ml/min/1.73 m(2)/year (fourth quartile)]. In the adjusted model, compared with participants in the fourth quartile, those in the first and/or second quartiles of annual eGFR change had significantly higher risk of renal disease and/or ASVD-associated clinical events. However, the association with renal clinical events was more pparent in participants with baseline eGFR of <60 ml/min/1.73 m(2). CONCLUSION The results of this study suggest that the inclusion of long-term eGFR change over time might augment prognostication for renal disease and ASVD-associated clinical events in elderly women.
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Affiliation(s)
- W H Lim
- University of Western Australia School of Medicine and Pharmacology, Sir Charles Gairdner Hospital Unit, Perth, Western Australia, Australia.
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Chong WY, Lim KS, Lim WH, Harun SW, Adikan FRM, Ahmad H. Spreading profile of evaporative liquid drops in thin porous layer. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:016314. [PMID: 22400665 DOI: 10.1103/physreve.85.016314] [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] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 10/13/2011] [Indexed: 05/31/2023]
Abstract
Spreading of evaporative liquid drops in a thin porous layer has been studied. The entire spreading process can be divided into three distinct phases according to the change of the wetted porous region size. The first phase is characterized by the expansion of the wetted porous region and shrinking of the liquid drop. Contact line pinning is observed in the wetted porous region in the second phase even with the liquid drop totally absorbed into the porous layer. The third phase sees the shrinkage of the wetted porous region until it is not observable. Based on these observations, a model is devised to simulate the spreading of a liquid drop under the studied conditions. Partial differential equations are used to describe the relation between liquid drop volume and other important parameters of a fluid flow, including maximum wetted region diameter achieved, time taken to reach each spreading process phase, and evaporation rate. Calculated results are in good agreement with the experimental data.
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Affiliation(s)
- W Y Chong
- Photonic Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Abstract
We report the demonstration of a low-disorder silicon metal-oxide-semiconductor (Si MOS) quantum dot containing a tunable number of electrons from zero to N = 27. The observed evolution of addition energies with parallel magnetic field reveals the spin filling of electrons into valley-orbit states. We find a splitting of 0.10 meV between the ground and first excited states, consistent with theory and placing a lower bound on the valley splitting. Our results provide optimism for the realisation in the near future of spin qubits based on silicon quantum dots.
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Affiliation(s)
- W H Lim
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW 2052, Australia.
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Cheong YK, Lim KS, Lim WH, Chong WY, Zakaria R, Ahmad H. Note: Fabrication of tapered fibre tip using mechanical polishing method. Rev Sci Instrum 2011; 82:086115. [PMID: 21895293 DOI: 10.1063/1.3627374] [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] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Tapered fibre tips fabricated using mechanical polishing method is studied. The fibre tips are formed by sequential polishing flat-ended single mode fibres with decreasing aluminium oxide polishing film grit size. Based on the proposed technique, tapered fibre tips with cone angle ranging from 30° to 130° are fabricated by controlling the polishing angle. Besides the variety of cone angle, considerable smoothness of the fibre tip surface may assist in good metal coating and hence a well-defined aperture can be obtained. In addition, this paper presents a two-step hybrid fabrication method combining the proposed polishing method with chemical etching method to increase the possible fibre tip cone angles achievable by chemical etching method.
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Affiliation(s)
- Y K Cheong
- Photonics Research Centre, Physics Department, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
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Lim JE, Lee SJ, Kim YJ, Lim WH, Chun YS. Comparison of cortical bone thickness and root proximity at maxillary and mandibular interradicular sites for orthodontic mini-implant placement. Orthod Craniofac Res 2009; 12:299-304. [PMID: 19840282 DOI: 10.1111/j.1601-6343.2009.01465.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To compare maxillary and mandibular cortical bone thickness and rootic proximity for optimal mini-implant placement. SETTING AND SAMPLE POPULATION CT images from 14 men and 14 women were used to evaluate buccal interradicular cortical bone thickness and root proximity from mesial of the central incisor to the 2nd molar. Cortical bone thickness was measured at 0 degrees , 15 degrees , 30 degrees , and 45 degrees angles relative to the root surface using three-dimensional images. RESULTS For the cortical bone thickness, there was no statistically significant difference between the maxilla and the mandible in the anterior area; however, there was a significant difference in the posterior area. Cortical bone in the maxilla, mesial and distal to canine interradicular sites, was thickest while thickness in the mandible exhibited a gradual anterior to posterior increase. Cortical bone thickness in the maxilla increased as both level and angle increased, while the cortical bone thickness in the mandible was greatest at 4 mm from the alveolar crest. Root proximity mesial and distal to 2nd premolar interradicular sites was greatest. CONCLUSION Based on our results, cortical bone thickness depends on the interradicular site rather than sex or individual differences.
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Affiliation(s)
- J E Lim
- School of Clinical Dentistry, Ewha Womans University, Seoul, Korea
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Lim WH, Toothman J, Miller JH, Tallents RH, Brouxhon SM, Olschowka ME, Kyrkanides S. IL-1beta inhibits TGFbeta in the temporomandibular joint. J Dent Res 2009; 88:557-62. [PMID: 19587162 DOI: 10.1177/0022034509336823] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Similarly to humans, healthy, wild-type mice develop osteoarthritis, including of the temporomandibular joint (TMJ), as a result of aging. Pro-inflammatory cytokines, such as IL-1beta, IL-6, and TNFalpha, are known to contribute to the development of osteoarthritis, whereas TGFbeta has been associated with articular regeneration. We hypothesized that a balance between IL-1beta and TGFbeta underlies the development of TMJ osteoarthritis, whereby IL-1beta signaling down-regulates TGFbeta expression as part of disease pathology. Our studies in wild-type mice, as well as the Col1-IL1beta(XAT) mouse model of osteoarthritis, demonstrated an inverse correlation between IL-1beta and TGFbeta expression in the TMJ. IL-1beta etiologically correlated with joint pathology, whereas TGFbeta expression associated with IL-1beta down-regulation and improvement of articular pathology. Better understanding of the underlying inflammatory processes during disease will potentially enable us to harness inflammation for orofacial tissue regeneration.
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Affiliation(s)
- W H Lim
- Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, Korea
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Abstract
OBJECTIVES Implant stability is primarily related to local bone density; Few studies have evaluated interradicular bone density related to mini-implant placement for orthodontic anchorage. Therefore, this study evaluated bone density differences between interradicular sites. SETTING AND SAMPLE POPULATION Computed tomographic (CT) images were obtained from 14 males and 14 females (mean age 27 years, range 23-35 years). Bone density in Hounsfield units (HU) was measured at 13 interradicular sites and four bone levels. RESULTS Bone densities in most areas were higher than 850 HU. Statistically significant differences in bone density were detected at different levels and sites. Bone densities in both maxilla and mandible significantly increased from the alveolar crest toward basal bone in posterior areas, while the opposite was observed in anterior areas. There were statistically significant differences in bone densities between the maxilla and mandible in posterior areas. Bone densities progressively increased from anterior to posterior areas in the mandible. CONCLUSION The results suggest that mini-implants for orthodontic anchorage may be effective when placed in most areas with equivalent bone density up to 6 mm apical to the alveolar crest. Site selection should be adjusted according to bone density assessment.
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Affiliation(s)
- Y S Chun
- Division of Orthodontics, Department of Dentistry, Ewha Womans University, Seoul, Korea
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Chun YS, Lee SK, Wikesjö UME, Lim WH. The interdental gingiva, a visible guide for placement of mini-implants. Orthod Craniofac Res 2009; 12:20-4. [PMID: 19154271 DOI: 10.1111/j.1601-6343.2008.01433.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To determine whether the tip of the interdental gingiva can serve as a visible guide for placement of mini-implants. SETTING AND SAMPLE POPULATION Computer tomography (CT) images from 15 males and 15 females (mean age 27 years, range: 23-35 years) were used to evaluate the distance from the tip of the interdental gingiva to the alveolar crest from the central incisor to the 1st molar. The distance from a reference point to the tip of interdental gingiva was recorded from study models using a caliper. The distance between the reference point and the alveolar crest was recorded using CT and added to the model recordings thus providing the distance from the tip of interdental gingiva to the alveolar crest for the various interdental sites. Two-way anova and Student-Newman-Keuls test for multiple comparisons were used for the statistical analysis. RESULTS There was no significant difference in the distance from the tip of interdental gingiva to the alveolar crest between maxilla and mandible. The distance between the tip of interdental gingiva and the alveolar crest at the central/lateral incisors was the shortest compared with that of other sites. There was also a statistically significant difference between the male and female groups except for the maxillary 2nd premolar/1st molar interradicular site. CONCLUSION The tip of interdental gingiva appears a reasonable visual guide for the placement of mini-implants for orthodontic anchorage.
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Affiliation(s)
- Y S Chun
- Division of Orthodontics, Department of Dentistry, Ewha Womans University, Mokdong Hospital, Seoul, Korea
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Lim WH, Kireta S, Leedham E, Russ GR, Coates PT. Uremia impairs monocyte and monocyte-derived dendritic cell function in hemodialysis patients. Kidney Int 2007; 72:1138-48. [PMID: 17728708 DOI: 10.1038/sj.ki.5002425] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Patients with chronic renal failure maintained on intermittent hemodialysis have frequent infections and a suboptimal response to vaccinations. Dendritic cells are potent antigen-presenting cells essential for the initiation and maintenance of innate and adaptive immunity. In this study we used uremic sera from hemodialysis patients to measure its impact on monocyte and monocyte-derived dendritic cell function in vitro. Monocytes from healthy and uremic subjects were isolated using immunomagnetic beads and differentiated into dendritic cells in the presence of either complete sera or sera from hemodialysis patients. Dendritic cells from normal patients cultured in uremic sera had decreased endocytosis and impaired maturation. These cells, however, had enhanced IL-12p70 production and increased allogeneic T-cell proliferation compared to cells of normal subjects cultured in normal sera. Monocyte derived dendritic cells of hemodialysis patients cultured in either normal or uremic sera were functionally impaired for endocytosis and maturation but had enhanced IL-12p70 production and allogeneic T-cell proliferation only when cultured with uremic sera. High concentrations of urea in normal sera inhibited all aspects of normal dendritic cell function in vitro. Our study suggests that hemodialysis regimes tailored to remove uremic toxins more efficiently may improve immune functions of these patients.
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Affiliation(s)
- W H Lim
- Transplantation Immunology Laboratory and Department of Medicine, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia
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Abstract
Patients on hemodialysis have a general immunodeficiency involving both innate and adaptive responses. As the mechanisms contributing to this defect are uncertain, we sought to study the effects of uremia on circulating dendritic cells (DC) in hemodialysis patients. Immunomagnetic beads were used to isolate myeloid and plasmacytoid DCs from healthy donors. Immune-related functions were determined in these cells cultured in either a complete media containing ABO-compatible serum or media containing sera from uremic patients. The myeloid cells were analyzed for costimulatory molecule expression and allo-stimulatory capability following lipopolysaccharide stimulation. The production of interferon-alpha following herpes-simplex virus stimulation by the plasmacytoid cells was also measured. Myeloid DCs incubated with uremic sera demonstrated impaired maturation and decreased allo-stimulatory capacity. Similarly, herpes virus-stimulated plasmacytoid DCs incubated with uremic sera produced significantly less interferon-alpha compared with cells incubated in the complete media. Both small and large molecule uremic toxins inhibited DC functions in vitro. Use of more efficient dialysis to improve small molecule clearance reversed the inhibition of uremic sera on myeloid but not plasmacytoid DC function. We have shown that the immunodeficiency of hemodialysis patients is due to dialyzable uremic toxins.
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Affiliation(s)
- W H Lim
- Transplantation Immunology Laboratory, Department of Medicine, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia
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Suh SP, Kee SJ, Lim WH, Song JW, Lee SK, Kim JP, Shin JH, Ryang DW. Multiplex in-cell reverse transcription-polymerase chain reaction for the simultaneous detection of p210 and p190 BCR-ABL mRNAs in chronic myeloid leukemia and Philadelphia-positive acute lymphoblastic leukemia cell lines. Clin Chem Lab Med 2000; 38:939-44. [PMID: 11097354 DOI: 10.1515/cclm.2000.138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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: 11/15/2022]
Abstract
We designed a novel multiplex in-cell reverse transcription-polymerase chain reaction method for the simultaneous detection and differentiation of p190 and p210 BCR-ABL mRNAs within single cells from the human chronic myeloid leukemia and Philadelphia positive acute lymphoblastic leukemia. Human K562 chronic myeloid leukemia and SUP B-15 Ph+ acute lymphoblastic leukemia cell lines were used as positive controls for p210 and p190 BCR-ABL mRNAs, respectively. HL60 cell line was used as a negative control. After the leukemia cells were fixed and permeabilized, without extracting nucleic acids, the mRNAs were reverse transcribed to cDNAs, and the cDNAs were amplified by multiplex polymerase chain reaction with fluorescent primers specific for p190 and p210 BCR-ABL mRNAs. After transfer onto glass slides by cytospin, the amplified cells were detected by fluorescence microscopy. Fluorescence microscopy after propidium iodide or 4',6-diamidino-2-phenylindone counterstaining showed that the positive K562 cells exhibited a yellow-green fluorescent cytoplasm around a red nucleus, and that the positive SUP B-15 cells exhibited an orange cytoplasm around a blue nucleus. Only the red or blue nucleus was visible in respective negative HL60 cells. The specificity of amplification was confirmed by the absence of a signal when control experiments were performed either with RNase digestion of mRNA or without reverse transcriptase/Taq polymerase. We conclude that the multiplex in-cell reverse transcription-polymerase chain reaction method is capable of simultaneously detecting and differentiating the p210 and p190 BCR-ABL mRNAs of chronic myeloid leukemia and Philadelphia-positive acute lymphoblastic leukemia cells, and that it may be useful in quantitatively monitoring the minimal residual disease during therapy.
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Affiliation(s)
- S P Suh
- Department of Clinical Pathology, Chonnam National University Medical School, Kwangju, Korea.
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Verma A, Dhawan A, Wade JJ, Lim WH, Ruiz G, Price JF, Hadzic N, Baker AJ, Rela M, Heaton ND, Mieli-Vergani G. Mycobacterium tuberculosis infection in pediatric liver transplant recipients. Pediatr Infect Dis J 2000; 19:625-30. [PMID: 10917220 DOI: 10.1097/00006454-200007000-00008] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES To study the incidence, clinical presentation, management, complications and outcome of tuberculosis in pediatric liver transplant recipients. METHODS A retrospective review of the medical records of children who underwent liver transplantation between 1991 and 1998. RESULTS Mycobacterium tuberculosis infection occurred in 6 of 254 (2.4%) children undergoing liver transplantation between 1991 and 1998. Cough, pyrexia and poor appetite were common presentations; one-half had normal chest radiographs. The median time to confirmation of diagnosis was 8 months (range, 1 to 17 months). Tests contributing to diagnosis included: Ziehl-Neelsen (ZN) stain (2 patients), M. tuberculosis polymerase chain reaction (1 patient), Mantoux test (1 patient) and histopathology (4 patients). Family health screening was productive for 4 patients. Duration of treatment varied from 9 to 18 months. Isoniazid-induced hepatitis was observed in 2 patients but resolved with dose reduction. Two patients died while receiving treatment, one of Klebsiella spp. septicemia and the other of pulmonary hemorrhage. CONCLUSIONS Tuberculosis after liver transplantation has a significant morbidity and mortality. Pretransplantation a personal and family history of tuberculosis must be sought, and screening of patients and their families should be considered. Standard regimens incorporating isoniazid and rifampin are effective, but regular monitoring of liver function is essential to detect drug-induced hepatotoxicity.
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Affiliation(s)
- A Verma
- Dulwich Public Health Laboratory and Medical Microbiology, King's College Hospital, London, UK.
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Chay OM, Goh A, Abisheganaden J, Tang J, Lim WH, Chan YH, Wee MK, Johan A, John AB, Cheng HK, Lin M, Chee T, Rajan U, Wang S, Machin D. Obstructive sleep apnea syndrome in obese Singapore children. Pediatr Pulmonol 2000; 29:284-90. [PMID: 10738016 DOI: 10.1002/(sici)1099-0496(200004)29:4<284::aid-ppul8>3.0.co;2-d] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We set out to determine the prevalence of obstructive sleep apnea syndrome (OSAS) among obese Singapore school children and identify risk factors for OSAS. This study was designed as a prospective study in three phases. Parents completed a questionnaire with regards to sleep and daytime symptoms in Phase 1. Children suspected to have OSAS based on the questionnaire and all with a percent ideal body weight (IBW) >/=180 were called for clinic visits in Phase 2. All whose percent IBW >/=180 and those in whom the physicians strongly suspected OSAS were subjected to a polysomnogram in phase 3. The children were recruited from the School Health Nutritional Clinic for obese children. The investigations were carried out at Tan Tock Seng Hospital. In all, 3,671 children were screened with the questionnaire. Of these, 146 were selected to undergo polysomnography. Twenty-six had abnormal sleep studies with apnea/hypoxia indices (AHIs) >5/hr. The significant clinical feature which correlated with OSAS was sleep sitting up (P = 0.005). The risk is higher in morbidly obese (IBW >/=180), with a prevalence of 13.3% (8/60), than in less obese children (IBW <180). One in eight (12.5%) of these children was asymptomatic and would have been missed based on the questionnaire. Presence of adenotonsillar hypertrophy led to increased risk of OSAS. The prevalence of OSAS was 0.7% (26/3,671) among the obese schoolchildren in Singapore, which is similar to the prevalence reported by others. Using discriminant analysis, the estimated prevalence increased to 5.7%. In the morbidly obese (IBW >/=180), the prevalence rate is higher at 13.3%.
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Affiliation(s)
- O M Chay
- Respiratory Medicine Service, Department of Paediatrics, KK Women's and Children's Hospital, Singapore
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Abstract
Long-term usage of systemic steroids is associated with multiple side effects. One of the major morbidities is due to its effect on bone metabolism leading to bone loss and resulting in skeletal fractures. This study was conducted to determine the effects of inhaled steroids on bone mineral density (BMD) and biochemical bone markers. Twenty-four children with frequent episodic or mild persistent asthma who satisfied the clinical criteria for starting on inhaled corticosteroids (ICS) were enrolled into the study. The BMD scan was done using dual energy X-ray absorptiometry, prior to starting ICS therapy and 6 months later. Biochemical markers of bone metabolism, (i) serum osteocalcin as a bone formation marker, and (ii) urinary deoxypyridinoline (Upd) as a bone resorption marker, were taken prior to ICS treatment and at 2 monthly intervals. The biochemical markers were all taken in the morning. Twenty-four, age- and sex-matched children with mild episodic asthma, not requiring ICS, were used as controls for the BMD measurements. The BMD scan was done upon enrollment into the study and 6 months later. Twenty-four children on ICS and 24 controls completed the study. The subjects were on a mean dose of beclomethasone dipropionate (BDP) 0.4 mg/day. One subject needed a short course of Prednisolone in the early treatment period. None of the controls needed oral steroid therapy. One child in the control group sustained a greenstick fracture after an accidental fall. The mean rate of change of BMD was 1.8% +/- 12.3 in the subjects on BDP. This was lower than the 6.1% +/- 10.6 among the control subjects. However, this difference did not reach statistical significance (P = 0.16). There was a significant increase in serum osteocalcin level after 6 months of BDP treatment from 66.83 +/- 22.71 ng/mL to 81.61 +/- 24.66 ng/mL (P < 0.005). There was a decline in Upd from 36.2 +/- 47.1 nmol/mmol creatinine to 21.4 +/- 6.92 nmol/mmol creatinine. However, this did not reach statistical significance. There was no difference in the statural gain between the subjects on ICS and their controls. This study showed that 6 months of ICS therapy (mean dose 0.4 mg/day) had no significant adverse effect on bone metabolism in asthmatic children.
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Affiliation(s)
- O M Chay
- Tan Tock Seng Hospital, Republic of Singapore
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Chong CY, Lim WH, Heng JT, Chay OM. The changing trend in the pattern of infective etiologies in childhood acute lower respiratory tract infection. Acta Paediatr Jpn 1997; 39:317-21. [PMID: 9241892 DOI: 10.1111/j.1442-200x.1997.tb03744.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The etiologic agents causing acute lower respiratory tract infection (LRTI) in hospitalized children were compared for 1995 and 1988. Between May 1994 to April 1995, 397 children were admitted to Tan Tock Seng Hospital for acute LRTI compared to 240 children in 1988. The following criteria for LRTI were used: (i) age less than 12 years with a community-acquired LRTI; (ii) presence of cough or fever of less than 2 weeks' duration; and (iii) presence of tachypnea, chest retractions or pulmonary infiltrates on chest X-ray. Sputum cultures were considered suitable for culture if there were less than 25 epithelial cells per low power field. Moraxella catarrhalis was considered only if heavy growth of more than 3+ was seen. Etiological agents were found in about 70% of patients in both studies. Viruses constituted 41.3% of the etiologic agents in 1995 but constituted only 28% in 1988; 36% had a bacterial etiology in 1995 compared to 15% in 1988. The most common bacteria in 1995 was M. catarrhalis (34.7%) followed by non-type B Haemophilus influenzae (33%). In contrast, in 1988, Mycoplasma (33%) was the predominant organism followed by H. influenzae (17%) and M. catarrhalis (11.4%). The increased incidence of M. catarrhalis could be due to antibiotic selection. A mixed viral-bacterial etiology was found in 12.3% of the 1995 cohort. The majority of the bacteria were positive by sputum cultures; only 4 (3.3%) had positive blood cultures. No penicillin resistance was detected in 1988; however, in 1995, penicillin resistance was found in 17% of the Streptococcus pneumoniae, 38.5% of H. influenzae and 83% of M. catarrhalis. It was also found that 30% of the S. pneumoniae were also resistant to erythromycin, and 23% were resistant to sulfamethoxaxole-trimethoprim; 5% of the H. influenzae had multiple resistance to erythromycin, sulfamethoxazole-trimethoprim and chloramphenicol. Among those patients with antibiotic resistance, 30% had received prior antibiotics of which 18% had had two or more antibiotics, frequently erythromycin or amoxycillin/ampicillin. Judicious use of antibiotics is required to check the rising trend of antibiotic resistance.
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Affiliation(s)
- C Y Chong
- Department of Paediatrics, Tan Tock Seng Hospital, Singapore
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Abstract
Macrophage activation is accompanied by reductions in prostacyclin generation and platelet-activating factor (PAF) levels, but the mechanism has not been identified. We have investigated the involvement of glucocorticoid-sensitive mechanisms and endogenous PAF in this phenomenon. The synthetic glucocorticoid, dexamethasone (1 microM) reduced basal prostacyclin and PAF generation in resident, but not in activated macrophages. PAF receptor antagonists or dexamethasone reduced the basal, but not stimulation-induced prostacyclin generation in resident macrophages. Dexamethasone and PAF antagonists did not have synergistic inhibitory effects on prostacyclin generation by resident macrophages, and the reduction was less than that which accompanies macrophage activation. Thus, differences in the effects of PAF receptor antagonists and dexamethasone compared with macrophage activation on zymosan-induced prostacyclin synthesis indicate that factors other than PAF or glucocorticoid-sensitive mechanisms contribute to this phenomenon. Subsequent experiments with culture media conditioned by resident macrophages indicated the presence of a soluble factor which increases prostacyclin generation and appears to be absent in media conditioned by activated macrophages.
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Affiliation(s)
- W H Lim
- Department of Physiology, University of Melbourne, Australia
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Lim WH, Stewart AG. Macrophage activation reduces mobilization of arachidonic acid by guinea-pig and rat peritoneal macrophages in vitro. Agents Actions 1990; 31:290-7. [PMID: 2128165 DOI: 10.1007/bf01997622] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have examined species differences in the mobilization of arachidonic acid and generation of prostacyclin in non-activated and activated peritoneal macrophages in vitro. Mobilization of 3H-arachidonic acid was reduced in rat activated macrophages compared with that in non-activated macrophages, but a similar difference was not observed in guinea-pig macrophages. In guinea-pig peritoneal macrophages, exposure to formyl-Methionyl-Leucyl-Phenylalanine (fMLP), platelet-activating factor (Paf), zymosan and A23187 increased the generation of prostacyclin. In contrast, in rat peritoneal macrophages, fMLP and Paf did not stimulate the mobilization of arachidonic acid or the generation of prostacyclin, whereas both zymosan and A23187 were effective stimuli. Pretreatment of either rats or guinea-pigs by intraperitoneal injection of C. Parvum reduced prostacyclin generation by peritoneal macrophages in vitro. We conclude that there may be species differences in receptor populations between guinea-pig and rat peritoneal macrophages. However, the reduction in eicosanoid generation induced by the inflammatory stimulus, C. Parvum is not species-dependent.
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Affiliation(s)
- W H Lim
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia
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