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Tabakov S, Goh J, Cheung KY. IUPESM milestone developments and achievements during 1980-2022-a tribute to the contributors. Health Technol (Berl) 2022; 12:609-612. [PMID: 35474737 PMCID: PMC9023040 DOI: 10.1007/s12553-022-00667-6] [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] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 04/05/2022] [Indexed: 10/25/2022]
Abstract
During 2020 the International Union for Physical and Engineering Sciences in Medicine (IUPESM) celebrated its 40th anniversary. At that time a paper was prepared tracing the main steps for the creation of the IUPESM (the Union formed of IOMP and IFMBE) and its very important activities for the global recognition of the professions [1]. The current paper, prepared by the IUPESM President, Vice-President and Past President, presents a chronology of the IUPESM Milestone Developments and Achievements and pays tribute to the main contributors for these achievements. Supplementary information The online version contains supplementary material available at 10.1007/s12553-022-00667-6.
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Affiliation(s)
| | - J Goh
- Department of Biomedical Engineering, National University of Singapore, Queenstown, Singapore
| | - K Y Cheung
- Hong Kong Sanatorium & Hospital, HKSH Eastern Medical Centre, Shau Kei Wan, Hong Kong
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Yang B, Tang KK, Geng H, Lam WW, Wong YS, Huang CY, Chiu TL, Kong CW, Cheung CW, Cheung KY, Yu SK. Comparison of modeling accuracy between Radixact ®and CyberKnife ®Synchrony ®respiratory tracking system. Biomed Phys Eng Express 2021; 7. [PMID: 34416743 DOI: 10.1088/2057-1976/ac1fa5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 08/20/2021] [Indexed: 11/12/2022]
Abstract
Synchrony Respiratory Tracking system adapted from CyberKnife has been introduced in Radixact to compensate the tumor motion caused by respiration. This study aims to compare the modeling accuracy of the Synchrony system between Radixact and CyberKnife. Two Synchrony plans based on fiducial phantoms were created for CyberKnife and Radixact, respectively. Different respiratory motion traces were used to drive a motion platform to move along the superoinferior and left-right direction. The cycle time and the amplitude of target/surrogate motion of one selected motion trace were scaled to investigate the dependence of modeling accuracy on the motion characteristic. The predicted target position, the correlation error, potential difference (Radixact only) and standard error (CyberKnife only) were extracted from raw data or log files of the two systems. The modeling accuracy was evaluated by calculating the root-mean-square (RMS) error between the predicted target positions and the input motion trace. A threshold T95 within which 95% of the potential difference or the standard error lay was defined and evaluated. Except for the motion trace with a small amplitude and a good (linear) correlation between target and surrogate motion, Radixact showed smaller RMS errors than CyberKnife. The RMS error of both systems increased with the motion amplitude and showed a decreasing trend with the increasing cycle time. No correlation was found between the RMS error and the amplitude of surrogate motion. T95 could be a good estimator of modeling accuracy for CyberKnife rather than Radixact. The correlation error defined in Radixact were largely affected by the number of fiducial markers and the setup error. In general, the modeling accuracy of the Radixact Synchrony system is better than that of the CyberKnife Synchrony system under unfavorable conditions.
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Affiliation(s)
- B Yang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K K Tang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - H Geng
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W W Lam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - Y S Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C Y Huang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - T L Chiu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C W Kong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C W Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K Y Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - S K Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
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Yang B, Wong YS, Lam WW, Geng H, Huang CY, Tang KK, Law WK, Ho CC, Nam PH, Cheung KY, Yu SK. Initial clinical experience of patient-specific QA of treatment delivery in online adaptive radiotherapy using a 1.5 T MR-Linac. Biomed Phys Eng Express 2021; 7. [PMID: 33882471 DOI: 10.1088/2057-1976/abfa80] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 10/30/2020] [Accepted: 04/21/2021] [Indexed: 11/11/2022]
Abstract
Purpose. This study aims to evaluate the performance of a commercial 1.5 T MR-Linac by analyzing its patient-specific quality assurance (QA) data collected during one full year of clinical operation.Methods and Materials. The patient-specific QA system consisted of offline delivery QA (DQA) and online calculation-based QA. Offline DQA was based on ArcCHECK-MR combined with an ionization chamber. Online QA was performed using RadCalc that calculated and compared the point dose calculation with the treatment planning system (TPS). A total of 24 patients with 189 treatment fractions were enrolled in this study. Gamma analysis was performed and the threshold that encompassed 95% of QA results (T95) was reported. The plan complexity metric was calculated for each plan and compared with the dose measurements to determine whether any correlation existed.Results. All point dose measurements were within 5% deviation. The mean gamma passing rates of the group data were found to be 96.8 ± 4.0% and 99.6 ± 0.7% with criteria of 2%/2mm and 3%/3mm, respectively. T95 of 87.4% and 98.2% was reported for the overall group with the two passing criteria, respectively. No statistically significant difference was found between adaptive treatments with adapt-to-position (ATP) and adapt-to-shape (ATS), whilst the category of pelvis data showed a better passing rate than other sites. Online QA gave a mean deviation of 0.2 ± 2.2%. The plan complexity metric was positively correlated with the mean dose difference whilst the complexity of the ATS cohort had larger variations than the ATP cohort.Conclusions. A patient-specific QA system based on ArcCHECK-MR, solid phantom and ionization chamber has been well established and implemented for validation of treatment delivery of a 1.5 T MR-Linac. Our QA data obtained over one year confirms that good agreement between TPS calculation and treatment delivery was achieved.
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Affiliation(s)
- B Yang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - Y S Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W W Lam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - H Geng
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C Y Huang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K K Tang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W K Law
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C C Ho
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - P H Nam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K Y Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - S K Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
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Cheung KY. Apparatus that separated radiotherapy from radiology. Hong Kong Med J 2021; 27:76-79. [PMID: 33568565 DOI: 10.12809/hkmj-hkmms202102] [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] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- K Y Cheung
- Education and Research Committee, Hong Kong Museum of Medical Sciences Society
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Eriksson E, Lysell J, Larsson H, Cheung KY, Filippini D, Mak WC. Geometric Flow Control Lateral Flow Immunoassay Devices (GFC-LFIDs): A New Dimension to Enhance Analytical Performance. Research (Wash D C) 2019; 2019:8079561. [PMID: 31549085 PMCID: PMC6750055 DOI: 10.34133/2019/8079561] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/13/2019] [Indexed: 01/14/2023]
Abstract
The nitrocellulose (NC) membrane based lateral flow immunoassay device (LFID) is one of the most important and widely used biosensor platforms for point-of-care (PoC) diagnostics. However, the analytical performance of LFID has limitations and its optimization is restricted to the bioassay chemistry, the membrane porosity, and the choice of biolabel system. These bottom neck technical issues resulted from the fact that the conventional LFID design principle has not evolved for many years, which limited the LFID for advanced biosensor applications. Here we introduce a new dimension for LFID design and optimization based on geometric flow control (GFC) of NC membranes, leading to highly sensitive GFC-LFID. This novel approach enables comprehensive flow control via different membrane geometric features such as the width (w) and the length (l) of a constriction, as well as its input angle (θ1) and output angle (θ2). The GFC-LFID (w=0.5 mm, l=7 mm, θ1= 60°, θ2= 45°) attained a 10-fold increase in sensitivity for detection of interleukin-6 (IL-6), compared with conventional LFID, whereas reducing by 10-fold the antibody consumption. The GFC-LFID detects IL-6 over a linear range of 0.1–10 ng/mL with a limit of detection (LoD) of 29 pg/mL, which even outperforms some commercial IL-6 LFIDs. Such significant improvement is attained by pure geometric control of the NC membrane, without additives, that only relaying on a simple high throughput laser ablation procedure suitable for integration on regular large-scale manufacturing of GFC-LFIDs. Our new development on GFC-LFID with the combination of facile scalable fabrication process, tailored flow control, improved analytical performance, and reduced antibodies consumption is likely to have a significant impact on new design concept for the LFID industry.
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Affiliation(s)
- E Eriksson
- Biosensors and Bioelectronics Centre, IFM-Linköping University, 58183 Linköping, Sweden
| | - J Lysell
- Biosensors and Bioelectronics Centre, IFM-Linköping University, 58183 Linköping, Sweden
| | - H Larsson
- Biosensors and Bioelectronics Centre, IFM-Linköping University, 58183 Linköping, Sweden
| | - K Y Cheung
- IKE-Linköping University, 58185 Linköping, Sweden
| | - D Filippini
- Optical Devices Laboratory, IFM-Linköping University, 58183 Linköping, Sweden
| | - W C Mak
- Biosensors and Bioelectronics Centre, IFM-Linköping University, 58183 Linköping, Sweden
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Mak WC, Magne B, Cheung KY, Atanasova D, Griffith M. Thermo-rheological responsive microcapsules for time-dependent controlled release of human mesenchymal stromal cells. Biomater Sci 2018; 5:2241-2250. [PMID: 28972602 DOI: 10.1039/c7bm00663b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Human mesenchymal stromal cells (hMSCs) are adult-source cells that have been extensively evaluated for cell-based therapies. hMSCs delivered by intravascular injection have been reported to accumulate at the sites of injury to promote tissue repair and can also be employed as vectors for the delivery of therapeutic genes. However, the full potential of hMSCs remains limited as the cells are lost after injection due to anoikis and the adverse pathologic environment. Encapsulation of cells has been proposed as a means of increasing cell viability. However, controlling the release of therapeutic cells over time to target tissue still remains a challenge today. Here, we report the design and development of thermo-rheological responsive hydrogels that allow for precise, time dependent controlled-release of hMSCs. The encapsulated hMSCs retained good viability from 76% to 87% dependent upon the hydrogel compositions. We demonstrated the design of different blended hydrogel composites with modulated strength (S parameter) and looseness of hydrogel networks (N parameter) to control the release of hMSCs from thermo-responsive hydrogel capsules. We further showed the feasibility for controlled-release of encapsulated hMSCs within 3D matrix scaffolds. We reported for the first time by a systematic analysis that there is a direct correlation between the thermo-rheological properties associated with the degradation of the hydrogel composite and the cell release kinetics. This work therefore provides new insights into the further development of smart carrier systems for stem cell therapy.
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Affiliation(s)
- W C Mak
- Department of Clinical and Experimental Medicine, Linköping University, SE58185, Linköping, Sweden.
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Abstract
OBJECTIVES Using both clinical parameters and subjective measures of oral health, this study aimed to identify useful oral health indicators for the risk of malnutrition in elders. DESIGN Cross-sectional study. SETTING Five community centers run by non-government organizations (NGOs). PARTICIPANTS 195 community dwelling elders (65 or above). MEASUREMENTS An interviewer-administered questionnaire was completed to collect information on elders' socio-demographic background and oral health perception and practice. Their number of teeth, number of occluding tooth pairs, dental caries, and periodontal condition were examined. General Oral Health Assessment Index (GOHAI), an instrument for assessing oral health related quality of life (OHQoL), was used as a subjective measure of oral health. The elders' nutritional status was evaluated by using the Mini-Nutritional Assessment (MNA). RESULTS The mean (SD) DFT was 3.3 (3.1). Over 60% of elders had periodontal pockets; 33% had fewer than 20 teeth and 6% were edentulous. The mean (SD) of occluding tooth pairs was 7.1 (4.8). The mean (SD) total GOHAI score was 56.4 (8.0); 60% reported negative impact of oral health on their quality of life. The mean (SD) MNA score was 25.0 (2.9); 30% had malnutrition or were at risk. After controlling for socio-demographic factors, none of the clinical indicators (dental caries, periodontal status, number of teeth, and number of occluding tooth pairs) were associated with risk of malnutrition (all p>0.05). Poorer OHQoL indicated a higher chance for malnutrition in both adjusted models (OR of 0.914; 95% CI of 0.850-0.982; p=0.014 and OR of 0.915; 95% CI of 0.852-0.984; p=0.017). Tooth loss and untreated decayed teeth (DT) were significant/marginally significant determinants of poor OHQoL. CONCLUSION Elders' tooth loss and unmet treatment need for dental caries were associated with compromised quality of life, which indicated increased likelihood for malnutrition.
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Affiliation(s)
- L L Wu
- Dr. Xiaoli Gao, Dental Public health, Faculty of Dentistry, The University of Hong Kong, 3rd Floor, Prince Philip Dental Hospital, 34 Hospital Road, Sai Ying Pun, Hong Kong, ;
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Chung KL, Cheung KY, Kam CW. Differential Diagnosis of Acute Calf Pain and Swelling with Emergency Ultrasound. HONG KONG J EMERG ME 2017. [DOI: 10.1177/102490790501200106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Acute calf pain and swelling are common causes of emergency department attendance. Differential diagnoses may mimic each other causing confusion and uncertainty in management. With emergency ultrasound, most of the differential diagnoses for acute calf pain and swelling can be identified with confidence. We present two cases of calf pain and swelling utilising ultrasound to clarify the diagnosis.
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Yang B, Wong WKR, Geng H, Lam WW, Ho YW, Kwok WM, Cheung KY, Yu SK. Filmless methods for quality assurance of Tomotherapy using ArcCHECK. Med Phys 2017; 44:7-16. [PMID: 28044341 DOI: 10.1002/mp.12009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [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: 05/30/2016] [Revised: 10/15/2016] [Accepted: 11/08/2016] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Tomotherapy delivers an intensity-modulated radiation therapy (IMRT) treatment by the synchronization of gantry rotation, multileaf collimator (MLC), and couch movement. This dynamic nature makes the quality assurance (QA) important and challenging. The purpose of this study is to develop some methodologies using an ArcCHECK for accurate QA measurements of the gantry angle and speed, MLC synchronization and leaf open time, couch translation per gantry rotation, couch speed and uniformity, and constancy of longitudinal beam profile for a Tomotherapy unit. METHODS Four test plans recommended by AAPM Task Group 148 (TG148) and the manufacturer were chosen for this study. Helical and static star shot tests are used for checking the leaves opened at the expected gantry angles. Another helical test is to verify the couch traveled the expected distance per gantry rotation. The final test is for checking the couch speed constancy with a static gantry. ArcCHECK can record the detector signal every 50 ms as a movie file, and has a virtual inclinometer for gantry angle measurement. These features made the measurement of gantry angle and speed, MLC synchronization and leaf open time, and longitudinal beam profile possible. A shaping parameter was defined for facilitating the location of the beam center during the plan delivery, which was thereafter used to calculate the couch translation per gantry rotation and couch speed. The full width at half maximum (FWHM) was calculated for each measured longitudinal beam profile and then used to evaluate the couch speed uniformity. Furthermore, a mean longitudinal profile was obtained for constancy check of field width. The machine trajectory log data were also collected for comparison. Inhouse programs were developed in MATLAB to process both the ArcCHECK and machine log data. RESULTS The deviation of our measurement results from the log data for gantry angle was calculated to be less than 0.4°. The percentage differences between measured and planned leaf open time were found to be within 0.5% in all the tests. Our results showed mean values of MLC synchronization of 0.982, 0.983, and 0.995 at static gantry angle 0°, 45°, and 135°, respectively. The mean value of measured couch translation and couch speed by ArcCHECK had less than 0.1% deviation from the planned values. The variation in the value of FWHM suggested the couch speed uniformity was better than 1%. The mean of measured longitudinal profiles was suitable for constancy check of field width. CONCLUSION Precise and efficient methods for measuring the gantry angle and speed, leaf open time, couch translation per gantry rotation, couch speed and uniformity, and constancy of longitudinal beam profile of Tomotherapy using ArcCHECK have been developed and proven to be accurate compared with machine log data. Estimation of the Tomotherapy binary MLC leaf open time is proven to be precise enough to verify the leaf open time as small as 277.8 ms. Our method also makes the observation and quantification of the synchronization of leaves possible.
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Affiliation(s)
- B Yang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W K R Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - H Geng
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W W Lam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - Y W Ho
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W M Kwok
- Biomedical Engineering Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K Y Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - S K Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
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Yang B, Geng H, Kong CW, Lam WW, Cheung KY, Yu SK. Dose rate versus gantry speed test in RapidArc commissioning: a feasibility study using ArcCHECK. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/aa5196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hui AT, Lam YO, Chan CK, Cheung KY, Fung BH, Ng PW. A case of refractory seizure with cognitive impairment due to anti-GABA encephalitis. Hong Kong Med J 2016; 22:509-11. [PMID: 27738301 DOI: 10.12809/hkmj154604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- A Th Hui
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
| | - Y O Lam
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
| | - C K Chan
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
| | - K Y Cheung
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
| | - B H Fung
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
| | - P W Ng
- Department of Medicine and Geriatrics, United Christian Hospital, Kwun Tong, Hong Kong
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Kron T, Azhari HA, Voon EO, Cheung KY, Ravindran P, Soejoko D, Inamura K, Han Y, Ung NM, TsedenIsh B, Win UM, Srivastava R, Marsh S, Farrukh S, Rodriguez L, Kuo M, Baggarley S, DilipKumara AH, Lee CC, Krisanachinda A, Nguyen XC, Ng KH. Medical physics aspects of cancer care in the Asia Pacific region: 2014 survey results. Australas Phys Eng Sci Med 2015; 38:493-501. [DOI: 10.1007/s13246-015-0373-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 08/24/2015] [Indexed: 11/29/2022]
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Choi HHF, Leung TM, Chiu TL, Yang B, Wu PM, Cheung KY, Yu SK. SU-E-T-534: Level of Residual Radioactivity of Activated Parts of a Decommissioned Cyclotron. Med Phys 2015. [DOI: 10.1118/1.4924896] [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: 11/07/2022] Open
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Cheung KY, Damilakis J. Message from the IOMP President, Dr. Kin Yin Cheung and the Chairman of the IOMP Education and Training Committee, Prof. John Damilakis on November 7, 2013: "International Day of Medical Physics". J Biomed Phys Eng 2013; 3:113-4. [PMID: 25505756 PMCID: PMC4204507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 11/24/2013] [Indexed: 11/25/2022]
Affiliation(s)
| | - J Damilakis
- The chairman of the IOMP Education and Training Committee
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Meghzifene A, do Carmo Lopes M, Cheung KY, Constantinou C, Andreo P, Brandan ME, Castellanos ME, Ige TA, Frey GH. IAEA contribution to international harmonization of guidelines for clinical medical radiation physicists. Med Phys 2013. [DOI: 10.1118/1.4815410] [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: 11/07/2022] Open
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Meghzifene A, Vano E, Le Heron J, Cheung KY. Roles and responsibilities of medical physicists in radiation protection. Eur J Radiol 2010; 76:24-7. [PMID: 20851545 DOI: 10.1016/j.ejrad.2010.06.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 06/15/2010] [Indexed: 10/19/2022]
Affiliation(s)
- Ahmed Meghzifene
- International Atomic Energy Agency, Division of Human Health, Vienna, Austria.
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Cheung KY, Lee SMS. Bootstrap variance estimation for Nadaraya quantile estimator. TEST-SPAIN 2010. [DOI: 10.1007/s11749-009-0137-y] [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: 10/21/2022]
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Cheung KY, Dunn ELW. A medium-term follow-up study of a cohort of Chinese patients after first hospitalisation in a gazetted hospital for mania. East Asian Arch Psychiatry 2010; 20:15-22. [PMID: 22351806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
OBJECTIVES To study the characteristics of a cohort of first-episode manic patients treated in a regional psychiatric unit in Hong Kong, to explore the predictors of re-admission, and to investigate their functional outcomes 4 years after first hospitalisation. METHODS This was a medium-term follow-up study, using retrospective review of hospital records and clinical interviews at follow-up. Forty-four Chinese patients diagnosed as having their first-episode mania were discharged from a gazetted psychiatric ward in Hong Kong between January 1999 and June 2002. Their clinical characteristics on admission and prescribed medications on discharge were investigated. Their re-admission status was charted. The patients were contacted for follow-up assessment of their functional outcome at 4 years after their first hospitalisation. RESULTS In our cohort of 44 patients, their first-episode mania mostly presented in young adulthood, as significantly disturbed behaviour deemed to require compulsory admission. Nineteen (43%) of the patients were re-admitted at least once within 4 years of being discharged, 6 of whom were re-admitted more than once. Compulsory admission at the first-episode mania predicted future re-admission. Alcohol and substance abuse were associated with earlier re-admission after the first-episode mania. None of the patients died. For those who were reassessed (28 patients), most lived with family members. In all, 21 patients were able to sustain open employment at 4 years after discharge. About half (n = 14) of the traceable patients were able to continue in full-time employment at 4 years, while 7 were doing part-time work. The median Global Assessment of Functioning score of the traceable group was 88. CONCLUSION The results of this local study on patients with their first-episode of hospitalisation for mania were comparable to findings reported in western studies.
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Affiliation(s)
- K Y Cheung
- Department of Psychiatry, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong.
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Ng KH, Cheung KY, Hu YM, Inamura K, Kim HJ, Krisanachinda A, Leung J, Pradhan AS, Round H, van Dorn T, Wong TJ, Yi BY. The role, responsibilities and status of the clinical medical physicist in AFOMP. Australas Phys Eng Sci Med 2009; 32:175-9. [DOI: 10.1007/bf03179236] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chan APH, Sieh KM, Leung SM, Cheung KY, Fung KY. Extracorporeal Foley catheter spring device mimicking an intervertebral foreign body in transforaminal lumbar interbody fusion surgery. Hong Kong Med J 2009; 15:397-398. [PMID: 19801702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Affiliation(s)
- Alexander P H Chan
- Department of Orthopaedics and Traumatology, Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong
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Kron T, Cheung KY, Dai J, Ravindran P, Soejoko D, Inamura K, Song JY, Bold L, Srivastava R, Rodriguez L, Wong TJ, Kumara A, Lee CC, Krisanachinda A, Nguyen XC, Ng KH. Medical physics aspects of cancer care in the Asia Pacific region. Biomed Imaging Interv J 2008; 4:e33. [PMID: 21611001 PMCID: PMC3097731 DOI: 10.2349/biij.4.3.e33] [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] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 11/17/2022] Open
Abstract
Medical physics plays an essential role in modern medicine. This is particularly evident in cancer care where medical physicists are involved in radiotherapy treatment planning and quality assurance as well as in imaging and radiation protection. Due to the large variety of tasks and interests, medical physics is often subdivided into specialties such as radiology, nuclear medicine and radiation oncology medical physics. However, even within their specialty, the role of radiation oncology medical physicists (ROMPs) is diverse and varies between different societies. Therefore, a questionnaire was sent to leading medical physicists in most countries/areas in the Asia/Pacific region to determine the education, role and status of medical physicists.Answers were received from 17 countries/areas representing nearly 2800 radiation oncology medical physicists. There was general agreement that medical physicists should have both academic (typically at MSc level) and clinical (typically at least 2 years) training. ROMPs spent most of their time working in radiotherapy treatment planning (average 17 hours per week); however radiation protection and engineering tasks were also common. Typically, only physicists in large centres are involved in research and teaching. Most respondents thought that the workload of physicists was high, with more than 500 patients per year per physicist, less than one ROMP per two oncologists being the norm, and on average, one megavoltage treatment unit per medical physicist.There was also a clear indication of increased complexity of technology in the region with many countries/areas reporting to have installed helical tomotherapy, IMRT (Intensity Modulated Radiation Therapy), IGRT (Image Guided Radiation Therapy), Gamma-knife and Cyber-knife units. This and the continued workload from brachytherapy will require growing expertise and numbers in the medical physics workforce. Addressing these needs will be an important challenge for the future.
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Affiliation(s)
- T Kron
- Physical Sciences, Peter MacCallum Cancer Centre, and RMIT University, Melbourne, Australia
| | - KY Cheung
- Department of Clinical Oncology, Prince of Wales Hospital, Hong Kong, China
| | - J Dai
- Cancer Institute (Hospital), Chinese Academy of Medical Sciences, China
| | - P Ravindran
- Department of Radiation Oncology, Christian Medical College, Vellore, India
| | - D Soejoko
- Physics Department, University of Indonesia, Jakarta, Indonesia
| | - K Inamura
- Dept of Radiology & Medical Engineering, Kansai University of International Studies, Hyogo, Japan
| | - JY Song
- Department of Radiation Oncology, Chonnam National University Hospital, Republic of Korea
| | - L Bold
- Radiotherapy Department, National Cancer Center, Ulaanbaatar, Mongolia
| | - R Srivastava
- B.P.Koirala Memorial Cancer Hospital, Bharatpur, Chitwan, Nepal
| | - L Rodriguez
- Department of Radiation Oncology, Jose R. Reyes Memorial Medical Center, Manila, Philippines
| | - TJ Wong
- Department of Therapeutic Radiology, National Cancer Centre, Singapore
| | - A Kumara
- Division of Medical Physics, National Cancer Institute, Sri Lanka
| | - CC Lee
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan
| | - A Krisanachinda
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - XC Nguyen
- K Hospital, National Cancer Institute, Hanoi, Vietnam
| | - KH Ng
- Department of Biomedical Imaging, University of Malaya, and Medical Physics Unit, University of Malaya Medical Centre, Kuala Lumpur, Malaysia
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Wong SKH, Chiu PWY, Leung SF, Cheung KY, Chan ACW, Au-Yeung ACM, Griffith JF, Chung SSC, Ng EKW. Concurrent chemoradiotherapy or endoscopic stenting for advanced squamous cell carcinoma of esophagus: a case-control study. Ann Surg Oncol 2007; 15:576-82. [PMID: 18057993 DOI: 10.1245/s10434-007-9679-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 09/12/2007] [Accepted: 09/12/2007] [Indexed: 12/17/2022]
Abstract
BACKGROUND We evaluated the role of chemoradiotherapy (CRT) for patients with inoperable squamous esophageal cancer. METHODS Patients with locally advanced or metastatic squamous esophageal carcinoma who received CRT were recruited. The CRT consists of continuous infusion of 5-fluorouracil at 200 mg/m(2)/day, and cisplatin at 60 mg/m(2) on days 1 and 22, with concurrent radiotherapy for a total of 50 to 60 Gy in 25 to 30 fractions over 6 weeks. Efficacy was assessed by endoscopy and computed tomographic scan before and 8 weeks after completion of the treatment program. Median survival and the need for palliative esophageal stenting were compared with another group of patients who received endoscopic stenting. RESULTS From 1996 to 2003, a total of 36 consecutive patients (33 male, mean +/- SD age 63.2 +/- 9.5 years) with T4 disease (81%) with or without cervical nodal metastasis (50%) received CRT, while 36 patients treated with endoscopic stenting alone were recruited as controls. Both groups were comparable in demographics, pretreatment dysphagia score, comorbidities, and tumor characteristics. CRT was completed in 32 patients (89%). There was no treatment-related mortality. Tumor volume was greatly reduced after CRT in 19 patients. Four patients (11%) received salvage esophagectomy 9 to 42 months after CRT. Compared with the stenting group, CRT statistically significantly improved 5-year survival (15% vs. 0%, P = .01), median survival (10.8 months vs. 4.0 months, P < .005), and need for stenting (22% vs. 100%, P = .005). CONCLUSIONS Palliative CRT can effectively improve the symptoms of dysphagia in patients with inoperable squamous esophageal carcinoma. It results in better survival compared with endoscopic stenting in these patients.
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Affiliation(s)
- Simon K H Wong
- Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
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23
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Chau MC, Leung SF, Kam KM, Cheung KY, Kwan WH, Yu KH, Chiu KW, Chan TC. Feasibility of using interpolated contours of targets and organs at risk in intensity-modulated radiation therapy treatment planning for advanced-stage nasopharyngeal carcinoma. ACTA ACUST UNITED AC 2007; 51:480-4. [PMID: 17803802 DOI: 10.1111/j.1440-1673.2007.01874.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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To assess the dosimetric effect of using interpolated contours in planning intensity-modulated radiation therapy (IMRT) for advanced T-stage nasopharyngeal carcinoma. The present study focused on T3-T4 tumours where the proximity of targets to neurological organs poses a stringent test on the feasibility of such an approach. Contours of targets and organs were delineated on CT images of 2.5-mm interval and a reference IMRT plan was generated. An investigative (INV) IMRT plan was then generated with the same planning protocol, but based on interpolated contours that replaced deleted contours on alternate slices. The reference and INV plans were compared. Regarding target coverage, all targets in the INV plans met the acceptance criteria except for the PTV in one case. Regarding organs, the mean dose to 1% volume of the brainstem and spinal cord in the INV plans were kept below their dose limits. No significant differences in the mean doses to others organs were found. Satisfactory target coverage and protection of critical organs to a degree similar to full-scale contouring could be achieved with use of interpolated contours. The saving in manpower time for contouring is expected to significantly improve the throughput of the IMRT planning process.
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Affiliation(s)
- M C Chau
- Department of Clinical Oncology, Prince of Wales Hospital, Shatin, Hong Kong SAR.
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Abstract
Gout or pseudogout, caused by deposition of crystals, rarely affects the spine. We report 4 cases with gout or pseudogout in the lumbar spine. Two had cauda equina syndrome and another 2 had spinal stenosis. To avoid unnecessary surgery, this should be considered in the differential diagnosis when treating patients with histories of gout or pseudogout for spinal problems.
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Affiliation(s)
- H Y Lam
- Department of Orthopaedics and Traumatology, Alice Ho Miu Ling Nethersole Hospital, Hong Kong.
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Hawkins JA, Boutaoui N, Cheung KY, Van Klinken RD, Hughes CE. Intercontinental dispersal prior to human translocation revealed in a cryptogenic invasive tree. New Phytol 2007; 175:575-587. [PMID: 17635232 DOI: 10.1111/j.1469-8137.2007.02125.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In this study, complementary species-level and intraspecific phylogenies were used to better circumscribe the original native range and history of translocation of the invasive tree Parkinsonia aculeata. Species-level phylogenies were reconstructed using three chloroplast gene regions, and amplified fragment length polymorphism (AFLP) markers were used to reconstruct the intraspecific phylogeny. Together, these phylogenies revealed the timescale of transcontinental lineage divergence and the likely source of recent introductions of the invasive. The sequence data showed that divergence between North American and Argentinean P. aculeata occurred at least 5.7 million years ago, refuting previous hypotheses of recent dispersal between North and South America. AFLP phylogenies revealed the most likely sources of naturalized populations. The AFLP data also identified putatively introgressed plants, underlining the importance of wide sampling of AFLPs and of comparison with uniparentally inherited marker data when investigating hybridizing groups. Although P. aculeata has generally been considered North American, these data show that the original native range of P. aculeata included South America; recent introductions to Africa and Australia are most likely to have occurred from South American populations.
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Affiliation(s)
- J A Hawkins
- School of Biological Sciences, Plant Sciences Laboratories, University of Reading, Reading, Berkshire RG6 6AS, UK
| | - N Boutaoui
- School of Biological Sciences, Plant Sciences Laboratories, University of Reading, Reading, Berkshire RG6 6AS, UK
| | - K Y Cheung
- School of Biological Sciences, Plant Sciences Laboratories, University of Reading, Reading, Berkshire RG6 6AS, UK
| | - R D Van Klinken
- CSIRO Entomology and CRC for Australian Weed Management, Long Pocket Laboratories, 120 Meiers Road, Indooroopilly, QLD 4068, Australia
| | - C E Hughes
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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Tong WY, Djurisić AB, Xie MH, Ng ACM, Cheung KY, Chan WK, Leung YH, Lin HW, Gwo S. Metal Phthalocyanine Nanoribbons and Nanowires. J Phys Chem B 2006; 110:17406-13. [PMID: 16942077 DOI: 10.1021/jp062951q] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanoribbons and nanowires of different metal phthalocyanines (copper, nickel, iron, cobalt, and zinc), as well as copper hexadecafluorophthalocyanine (F(16)CuPc), have been grown by organic vapor-phase deposition. Their properties, as a function of substrate type, source-to-substrate distance, and substrate temperature, were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and absorption measurements. The size and morphology of the nanostructures were found to be mainly determined by the substrate temperature. The crystal structure was dependent on the substrate temperature as well. At substrate temperatures below 200 degrees C, in addition to straight nanoribbons, twisted nanoribbons were found for all investigated materials except F(16)CuPc, which formed helical nanoribbons upon exposure to an electron beam. The formation of different nanostructures (nanoribbons, twisted nanoribbons, and helical nanoribbons) is discussed.
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Affiliation(s)
- W Y Tong
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong
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Kam MK, Leung SF, Kwan WH, Chau RM, Cheung KY, Yu KH, Chiu SK, Chan AT. Pattern of local failure after primary 2-dimensional radiotherapy (2DRT) in non-metastatic nasopharyngeal carcinoma patients: Predominance of within-field failure and hints on dose escalation effect. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.15506] [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: 11/20/2022] Open
Abstract
15506 Background: To investigate the pattern of local failure and explore any dose-response effect in locally recurred NPC patients treated by 2DRT. Methods: Based on a retrospective review on 2DRT-planned, non-metastatic NPC patients treated between 1996–99, 50 patients had local recurrence (LR). Computer tomography (CT) images at primary treatment and at LR were co-registered for each patient. The pre-treatment gross tumor volumes (GTV) and LR volumes were mapped, and 3-dimensional (3D)dosimetric reconstruction were performed. 20 patients were excluded due to insufficient data. All patients (n = 30) were treated with 2DRT (median dose 66 Gy), and 15 received additional external boost (median dose 20 Gy). The 66 Gy isodose level (IL) was taken as prescription reference. Patterns of LR were classified according to the table below. Comparisons of mean dose (D mean) between LR volume and non-recurrent GTV (GTV-LR) were performed using Wilcoxon signed ranks test. Results: The proportion of within-field (IF) failure, marginal failure, and outside-field failure for the entire cohort were 83.3% (25/30), 13.3% (4/30), and 3.3% (1/30), respectively. Elements of sub-optimal target coverage and radiographic miss were identified in 13.3% (4/30) and 16.6% (5/30) of patients, respectively. The D mean within the non-recurrent GTV was statistically higher than that in the LR volume (73.3 Gy v.s. 69.9 Gy, p = 0.037). Conclusions: Improvement in target localization or dose distribution alone can only avoid less than 20% of local failure that is attributable to radiographic miss or sub-optimal target coverage. Within-field failure was the predominant mode of local recurrence. The dose-response effect observed in this study is hypothesis-generating and forms the background for future randomized trials to verify the dose-escalation benefit using modern radiotherapy technique with high conformal capacity. [Table: see text] No significant financial relationships to disclose.
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Affiliation(s)
- M. K. Kam
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - S. F. Leung
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - W. H. Kwan
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - R. M. Chau
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - K. Y. Cheung
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - K. H. Yu
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - S. K. Chiu
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
| | - A. T. Chan
- Prince of Wales Hospital, Chinese University of Ho, Hong Kong, Hong Kong Special Administrative Region of China
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Kam MK, Leung SF, Zee B, Choi PHK, Chau RMC, Cheung KY, Suen JJS, Teo PML, Kwan WH, Chan ATC. Impact of intensity-modulated radiotherapy (IMRT) on salivary gland function in early-stage nasopharyngeal carcinoma (NPC) patients: A prospective randomized study. J Clin Oncol 2005. [DOI: 10.1200/jco.2005.23.16_suppl.5501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- M. K. Kam
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - S. F. Leung
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - B. Zee
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - P. H. K. Choi
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - R. M. C. Chau
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - K. Y. Cheung
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - J. J. S. Suen
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - P. M. L. Teo
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - W. H. Kwan
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
| | - A. T. C. Chan
- Prince of Wales Hosp, Chinese Univ of Ho, Hong Kong, Hong Kong Special Administrative Region of China; Hong Kong Sanatorium and Hosp, Hong Kong, Hong Kong Special Administrative Region of China
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Kam MKM, Teo PML, Chau RMC, Cheung KY, Choi PHK, Kwan WH, Leung SF, Zee B, Chan ATC. Treatment of nasopharyngeal carcinoma with intensity-modulated radiotherapy: The Hong Kong experience. Int J Radiat Oncol Biol Phys 2004; 60:1440-50. [PMID: 15590175 DOI: 10.1016/j.ijrobp.2004.05.022] [Citation(s) in RCA: 403] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Revised: 04/07/2004] [Accepted: 05/13/2004] [Indexed: 10/26/2022]
Abstract
PURPOSE To evaluate the efficacy of using intensity-modulated radiotherapy (IMRT) in the primary treatment of nasopharyngeal carcinoma (NPC), including the role of dose escalation above 66 Gy level. METHODS AND MATERIALS Between July 2000 and September 2002, 63 newly diagnosed NPC patients were treated with IMRT. The disease was Stage I in 9 (14%), Stage II in 18 (29%), Stage III in 22 (35%), and Stage IV in 14 (22%). The prescribed dose was 66 Gy to the gross tumor volume (GTV) and positive neck nodes, 60 Gy to the planning target volume (PTV), and 54-60 Gy to the clinically negative neck. All 20 (100%) patients with T1-2a tumors received intracavitary brachytherapy (ICB) boost, and 15/42 (36%) patients with T2b-T4 tumors received conformal boost (8 Gy/4 fractions). Nineteen patients with advanced stage disease also received either neoadjuvant or concurrent chemotherapy. Acute and late normal tissue effects were graded according to the Radiation Therapy Oncology Group (RTOG) radiation morbidity scoring criteria. Local relapse-free survival (LRFS), nodal relapse-free survival (NRFS), distant metastasis-free survival (DMFS), and overall survival (OS) were estimated using the Kaplan-Meier method. RESULTS With a median follow-up of 29 months (range 8-45 months), 4 patients developed local in-field failure, 1 patient developed regional relapse, and 13 patients developed distant metastases. All 4 patients with local failure had either T3 or T4 disease before primary treatment and did not have ICB or conformal boost. The 3-year actuarial LRFS, NRFS, DMFS, and OS were 92%, 98%, 79%, and 90%, respectively. Multivariate analysis showed that dose escalation above 66 Gy was significantly associated with better PFS and DMFS, whereas GTV size was a significant adverse factor for OS. The worst acute mucositis was Grade 1 or 2 in 36 (59%), and Grade 3 in 25 (41%) patients. Acute dysphagia requiring tube feeding occurred in 5 (8%) patients. The proportion of patients with Grade 2-3 xerostomia was 57% at 3 months, and 23% at 2 years after IMRT. Within the subset of patients with a mean parotid dose of <31 Gy, the proportions with Grade 2-3 xerostomia were 30% and 17% at 3 months and 2 years, respectively. CONCLUSION Our experience of using IMRT in the primary treatment of NPC showed a very high rate of locoregional control and favorable toxicity profile. Furthermore, we found that dose escalation above 66 Gy of IMRT-based therapy was a significant determinant of progression-free survival and distant metastasis-free survival for advanced T-stage tumors. Distant metastases represent the predominant mode of treatment failure.
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Affiliation(s)
- Michael K M Kam
- Clinical Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
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Chan ATC, Ma BBY, Lo YMD, Leung SF, Kwan WH, Hui EP, Mok TSK, Kam M, Chan LS, Chiu SKW, Yu KH, Cheung KY, Lai K, Lai M, Mo F, Yeo W, King A, Johnson PJ, Teo PML, Zee B. Phase II study of neoadjuvant carboplatin and paclitaxel followed by radiotherapy and concurrent cisplatin in patients with locoregionally advanced nasopharyngeal carcinoma: therapeutic monitoring with plasma Epstein-Barr virus DNA. J Clin Oncol 2004; 22:3053-60. [PMID: 15284255 DOI: 10.1200/jco.2004.05.178] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To assess the efficacy of neoadjuvant paclitaxel and carboplatin (TC) followed by concurrent cisplatin and radiotherapy (RT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC) and to monitor treatment response with plasma Epstein-Barr virus (EBV) DNA. PATIENTS AND METHODS Thirty-one patients with International Union Against Cancer stages III and IV undifferentiated NPC had two cycles of paclitaxel (70 mg/m2 on days 1, 8, and 15) and carboplatin (area under the curve 6 mg/mL/min on day 1) on a 3-weekly cycle, followed by 6 to 8 weeks of cisplatin (40 mg/m2 weekly) and RT at 66 Gy in 2-Gy fractions. Plasma EBV DNA was measured serially using the real-time quantitative polymerase chain reaction method. Results All patients completed planned treatment. Response to neoadjuvant TC was as follows: 12 patients (39%) achieved partial response (PR) and 18 achieved (58%) complete response (CR) in regional nodes; five patients (16%) achieved PR and no patients achieved CR in nasopharynx. At 6 weeks after RT, one patient (3%) achieved PR and 30 patients (97%) achieved CR in regional nodes, and 31 patients (100%) achieved CR in nasopharynx; 29 patients (93%) had EBV DNA level of less than 500 copies/mL. Neoadjuvant TC was well tolerated, and the most common acute toxicity of cisplatin plus RT was grade 3 mucositis (55%). At median follow-up of 33.7 months (range, 7 to 39.3 months), six distant and three locoregional failures occurred. Plasma EBV DNA level increased significantly in eight of nine patients who experienced treatment failure but did not increase in those who did not. The 2-year overall and progression-free survival rates were 91.8% and 78.5%, respectively. CONCLUSION This strategy was feasible and resulted in excellent local tumor control. Serial plasma EBV DNA provides a noninvasive method of monitoring response in NPC.
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Affiliation(s)
- Anthony T C Chan
- Department of Clinical Oncology, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
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Abstract
Ten registered nurses working in a neonatal intensive care unit in Hong Kong were interviewed to explore their experiences of caring for infants whose disease is not responsive to curative treatment, their perceptions of palliative care, and factors influencing their care. Eight categories emerged from the content analysis of the interviews: disbelieving; feeling ambivalent and helpless; protecting emotional self; providing optimal physical care to the infant; providing emotional support to the family; expressing empathy; lack of knowledge and counselling skills; and conflicting values in care. The subtle cultural upbringing and socialization in nurse training and workplace environment also contributed to their moral distress. Hospital and nurse administrators should consider different ways of facilitating palliative care in their acute care settings. For example, by culture-specific death education, peer support groups, bereavement teams, modification of departmental policies, and a supportive work environment. Future research could include the identification of family needs and coping as well as ethical decision-making among nurses.
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MESH Headings
- Adaptation, Psychological
- Adult
- Attitude of Health Personnel
- Attitude to Health/ethnology
- Burnout, Professional/ethnology
- Burnout, Professional/etiology
- Burnout, Professional/prevention & control
- Burnout, Professional/psychology
- Clinical Competence/standards
- Conflict, Psychological
- Empathy
- Family/psychology
- Female
- Grief
- Health Knowledge, Attitudes, Practice
- Hong Kong
- Humans
- Infant, Newborn
- Intensive Care, Neonatal/methods
- Intensive Care, Neonatal/psychology
- Neonatal Nursing/methods
- Nursing Methodology Research
- Nursing Staff, Hospital/psychology
- Occupational Health
- Self-Help Groups
- Socialization
- Surveys and Questionnaires
- Terminal Care/methods
- Terminal Care/psychology
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Affiliation(s)
- B M Yam
- Department of Nursing, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT.
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32
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Abstract
The allele distributions at the 12 short tandem repeat (STR) loci D3S1358, HUMvWA, HUMFIBRA/FGA, HUMTHO1, HUMTPOX, HUMCSF1P0, D5S818, D13S317, D7S820, D8S1179, D21S11 and D18S51 have been determined for 284 unrelated Chinese in Hong Kong. The combined probability of identity for the 12 STR loci was about 4.1 x 10(-14) and the overall probability of excluding paternity 0.999978. None of the 12 loci were found to deviate from Hardy-Weinberg expectations according to the results of the exact test. There was also little evidence for association of alleles between loci. The results demonstrate that the loci are useful for forensic human identification and parentage testing for the Chinese population in Hong Kong.
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Affiliation(s)
- D M Wong
- Forensic Science Division, Government Laboratory, Ho Man Tin Government Offices, Chung Hau Street, Hong Kong, China.
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Chau RM, Teo PM, Choi PH, Cheung KY, Lee WY. Three-dimensional dosimetric evaluation of a conventional radiotherapy technique for treatment of nasopharyngeal carcinoma. Radiother Oncol 2001; 58:143-53. [PMID: 11166865 DOI: 10.1016/s0167-8140(00)00336-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND PURPOSE The aim of this study is to evaluate and delineate the deficiencies in conventional two-dimensional (2-D) radiotherapy planning of nasopharyngeal carcinoma (NPC) treatment and to explore the means for improvement of the existing treatment technique aiming at enhancing local tumor control and reducing treatment complications. METHODS AND MATERIALS Ten patients with NPC sparing the skull base and without intracranial extension or cranial nerve(s) palsy were chosen in the present study. Two sets of CT images for Phases I and II of the radiotherapy treatment were taken with patient immobilized in the flexed-head and the extended-head positions, respectively. Based on the CT images and endoscopic findings, the gross tumor volume (GTV) was defined. The clinical target volume (CTV) circumscribing the GTV was defined according to Ho's (Halnan, K.E. (ed.) Treatment of Cancer. London: Chapman and Hall, 1982. pp. 249-268) description of the organs at risk of tumor infiltration. The planning target volume (PTV) was defined by adding a margin to the CTV which catered for geometrical inaccuracies. The field borders and shields were set at standard distances from certain bony landmarks and were drawn on the simulator radiograph. Data on the beams and shield arrangements were then transferred to the planning computer via a digitizer. By applying 3-D volumetric dose calculation using a commercial three-dimensional (3D) treatment planning computer, the dose-volume-histograms (DVHs) of GTV, CTV, PTV and critical normal organs were generated for both phases of Ho's treatment technique. The same patients were re-planned using a modified Ho's technique which used 3-D beams-eye-view (BEV) in placing the shielding blocks and the same set of DVHs were generated and compared with those obtained from Ho's technique. RESULTS The median volumes of GTV, CTV and PTV covered by the 95% isodose in Ho's phase I treatment were around 60%. The dose coverage was unsatisfactory in the superior and inferior and the posterolateral regions. In phase II treatment, the median volume of GTV, CTV and PTV covered by the 95% isodose were 99, 96 and 72%, respectively. Even though the dose coverage of the PTV in both phases of treatment were unsatisfactory, radiotherapy with the original Ho's technique had consistently produced good local control for NPC. However, there is potential room for enhancing the local control further because after modifying Ho's technique by using 3-D BEV customization of the treatment portals, the median volume of the target covered by the 95% isodose was defined as V(95). The V(95) of the PTV during the Phase II treatment was improved by 13%. The 90% of the volume of temporo-mandibular joints and parotid glands were both irradiated to 53 Gy and 43.6 Gy of the total prescribed dose of 66 Gy, respectively, in phase I and II treatments. With the addition of a hypothalamus-pituitary shield to Ho's technique, 50% of the volume of optic chiasma and temporal lobes received, respectively, 19.3 Gy and 4.5 Gy. However, small volume of the temporal lobes received a maximum dose (D(max)) of 62.8 Gy (95.2% of 66Gy). Most of the brainstem was shielded from the lateral portals but 5% of its volume received a dose ranging from 25.4 to 50.4Gy. The spinal cord (at C1/C2 level) received a D(max) of 40.8 Gy in phase I and of 4.8 Gy in phase II. After modifying Ho's technique by 3-D BEV customization of the treatment portals, the D(max) to the brainstem, the optic chiasma and the temporal lobes could be reduced by 8, 12 and 5%, respectively. CONCLUSIONS Our study indicated that the dose-coverage of the PTV in Ho's radiotherapy technique for the early T-stage NPC was less than satisfactory in the superior and inferior and the posterolateral regions. However, in view of the excellent historical local tumor control with Ho's technique, we have to postulate that the present definition of CTV (and hence the PTV after adding margins to the CTV) lacks clinical significance and can be improved. It appears that the inclusion of the entire sphenoid sinus floor and both medial and lateral pterygoid muscles in the CTV is not necessary for maximal tumor control in the absence of clinical/radiological evidence of tumor infiltration of these organs. Ho's technique can be improved by using 3-D BEV to customize the treatment portals with multileaf collimators or blocks.
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Affiliation(s)
- R M Chau
- Department of Clinical Oncology, Prince of Wales Hospital, Shatin, Hong Kong, Peoples Republic of China
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Law MY, Wong DM, Fung WK, Chan KL, Li C, Lun TS, Lai KM, Cheung KY, Chiu CT. Genetic polymorphism at three STR loci--CSF1PO, HUMTHO1 and TPOX, and the AMP-FLP locus D1S80 for the Chinese population in Hong Kong. Forensic Sci Int 2001; 115:103-5. [PMID: 11056276 DOI: 10.1016/s0379-0738(00)00321-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Allele frequencies for three STR loci, namely, CSF1PO, HUMTHO1 and TPOX, and the AMP-FLP locus D1S80 were obtained from a sample of 351 unrelated Chinese in Hong Kong.
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Affiliation(s)
- M Y Law
- Forensic Science Division, Hong Kong Government Laboratory, Ho Man Tin Government Offices, 88 Chung Hau Street, Hong Kong, Kowloon, China
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Cheung KY, Choi PH, Chau RM, Lee LK, Teo PM, Ngar YK. The roles of multileaf collimators and micro-multileaf collimators in conformal and conventional nasopharyngeal carcinoma radiotherapy treatments. Med Phys 1999; 26:2077-85. [PMID: 10535623 DOI: 10.1118/1.598722] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The purpose of this work is to study the efficacy and limitations of using standard multileaf collimators (MLCs) and micro-multileaf collimators (mMLCs) in the treatment of nasopharyngeal carcinoma (NPC) by conventional and conformal radiotherapy techniques. The penumbra characteristics of MLC, mMLC, and customized block collimated beams are measured with respect to leaf edge angle, beam energy, treatment depth, and field size and compared with those generated by a commercial three-dimensional planning computer system. Upon verification of the planning system, it is used to evaluate the treatment plans generated with these beam shapers for conventional and conformal NPC treatments. The effective penumbra of a MLC beam is strongly influenced by its edge angle, leaf width, and treatment depth. The suitability of standard MLCs in conventional NPC treatments is determined mainly by the edge angle to be used. For conformal NPC treatments involving six or more fields, dose volume histograms comparable to those of customized beam blocks are obtained with a standard MLC. The mMLC does not have the same restrictions as those on standard MLC but is limited to phase II treatment by its small usable field size. Both standard MLCs and mMLCs can be used to replace customized divergent beam blocks in both conventional and conformal NPC treatments. However, a MLC, due to its larger effective penumbra, may be unsuitable for use in cases when the tumor volumes extend very close to the critical normal structures. A mMLC, on the other hand, is limited by its small maximum field size and can only be used for collimating the facial portals in the second phase treatment.
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Affiliation(s)
- K Y Cheung
- Department of Clinical Oncology, Prince of Wales Hospital, Shatin, Hong Kong
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Abstract
We isolated by differential screening a 1.2 kb cDNA from an Arabidopsis thaliana ecotype Columbia cDNA library that is highly expressed in stem and root. In situ hybridization studies on stem sections and root sections showed that the mRNA is expressed in stem sclerenchyma and root cortex, respectively. The isolation and sequence analysis of four other overlapping cDNA clones from two independent A. thaliana cDNA libraries confirmed that these cDNAs lack a significant open reading frame that has recognizable homology to any known proteins. We have obtained from A. thaliana ecotype Columbia three corresponding genomic clones and nucleotide sequence analysis of these clones revealed that we have isolated a retroposon, TSCL, that is flanked by two 13 bp direct repeats, is intronless, and has a poly(A)+ tract at the 3' end. The site of transcription initiation mapped by primer extension analysis lies 48 bp downstream from an external TATA box. Results from Southern blot analysis suggest that TSCL occurs as a single-copy insert in the genomes of A. thaliana ecotype Columbia (Col-0) and Col-2 but is absent in the genomes of Brassica napus. Brassica juncea and A. thaliana ecotypes Be-0, Oy-0 and Ler-0. This suggests that Col-0 and Col-2 are phylogenetically more closely related to each other than to Be-0, Oy-0 and Ler-0, and that the Laibach Landsberg seeds Redei received, from which ecotypes Col-0, Col-2 and Ler-0 originated, were heterogeneous for TSCL.
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Affiliation(s)
- M L Chye
- Department of Botany, University of Hong Kong
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Abstract
Clones encoding beta-1,3-glucanase have been isolated from a Hevea cDNA library prepared from the latex of Hevea brasiliensis using a probe Nicotiana plumbaginifolia cDNA encoding beta-1,3-glucanase, gnl. Nucleotide sequence analysis showed that a 1.2 kb Hevea cDNA encoding a basic beta-1,3-glucanase showed 68% nucleotide homology to gnl cDNA. Northern blot analysis using the Hevea cDNA as probe detected a mRNA of 1.3 kb which was expressed at higher levels in latex than in leaf. In situ hybridization analysis using petiole sections from Hevea localized the beta-1,3-glucanase mRNA to the laticifer cells. Genomic Southern analysis suggested the presence of a low-copy gene family encoding beta-1,3-glucanases in H. brasiliensis.
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Affiliation(s)
- M L Chye
- Department of Botany, University of Hong Kong, Hong Kong
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Abstract
A patient with classical neurofibromatosis is reported in whom malignant transformation of neurofibromas at multiple sites occurred, leading to a fatal outcome. One of these malignant tumours developed within the thyroid gland.
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Affiliation(s)
- M D Leslie
- Department of Surgery, Royal Free Hospital, Hampstead, London, UK
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Cheung KY, Miley GH. On Thermal-Neutron Pulse Propagation. NUCL SCI ENG 1966. [DOI: 10.13182/nse66-a18309] [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] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- K. Y. Cheung
- Nuclear Engineering Program University of Illinois Urbana, Illinois
| | - G. H. Miley
- Nuclear Engineering Program University of Illinois Urbana, Illinois
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