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Abdulkadir BA, Jalil AA, Cheng CK, Setiabudi HD. Progress and Advances in Porous Silica-based Scaffolds for Enhanced Solid-state Hydrogen Storage: A Systematic Literature Review. Chem Asian J 2024; 19:e202300833. [PMID: 37997488 DOI: 10.1002/asia.202300833] [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: 09/23/2023] [Revised: 11/13/2023] [Accepted: 11/21/2023] [Indexed: 11/25/2023]
Abstract
Hydrogen plays a crucial role in the future energy landscape owing to its high energy density. However, finding an ideal storage material is the key challenge to the success of the hydrogen economy. Various solid-state hydrogen storage materials, such as metal hydrides, have been developed to realize safe, effective, and compact hydrogen storage. However, low kinetics and thermodynamic stability lead to a high working temperature and a low hydrogen sorption rate of the metal hydrides. Using scaffolds made from porous materials like silica to confine the metal hydrides is necessary for better and improved hydrogen storage. Therefore, this article reviews porous silica-based scaffolds as an ideal material for improved hydrogen storage. The outcome showed that confining the metal hydrides using scaffolds based on porous silica significantly increases their storage capacities. It was also found that the structural modifications of the silica-based scaffold into a hollow structure further improved the storage capacity and increased the affinity and confinement ability of the metal hydrides, which prevents the agglomeration of metal particles during the adsorption/desorption process. Hence, the structural modifications of the silica material into a fibrous and hollow material are recommended to be crucial for further enhancing the metal hydride storage capacity.
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Affiliation(s)
- B A Abdulkadir
- Centre for Research in Advanced Fluid & Processes, Universiti Malaysia Pahang Al-Sultan Abdullah, Lebuh Persiaran Tun Khalil Yaakob, 26300, Gambang, Pahang, Malaysia
| | - A A Jalil
- School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310 UTM, Johor Bahru, Johor, Malaysia
- Centre of Hydrogen Energy, Institute of Future Energy, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - C K Cheng
- Center for Catalysis and Separation (CeCaS), Department of Chemical Engineering, College of Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates
| | - H D Setiabudi
- Centre for Research in Advanced Fluid & Processes, Universiti Malaysia Pahang Al-Sultan Abdullah, Lebuh Persiaran Tun Khalil Yaakob, 26300, Gambang, Pahang, Malaysia
- Faculty of Chemical & Process Engineering Technology, Universiti Malaysia Pahang Al-Sultan Abdullah, Lebuh Persiaran Tun Khalil Yaakob, 26300, Gambang, Pahang, Malaysia E-mail: address
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Teoh JYC, Tian XY, Wong CYP, Lau CW, Cheng CK, Tang VWL, Chan RCK, Huang Y, Ng CF. Endothelial dysfunction after androgen deprivation therapy and the possible underlying mechanisms. Prostate 2022; 82:13-25. [PMID: 34570375 DOI: 10.1002/pros.24244] [Citation(s) in RCA: 2] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/28/2021] [Accepted: 09/12/2021] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Androgen deprivation therapy (ADT) is a key treatment modality in the management of prostate cancer (PCa), especially for patients with metastatic disease. Increasing evidences suggest that patients who received ADT have increased incidence of diabetes, myocardial infarction, stroke, and even mortality. It is important to understand the pathophysiological mechanisms on how ADT increases cardiovascular risk and induces cardiovascular events, which would provide important information for potential implementation of preventive measures. METHODS Twenty-six 12-week-old male SD rats were divided into four groups for different types of ADTs including: the bilateral orchidectomy group (Orx), LHRH agonist group (leuprolide), LHRH antagonist group (degarelix), and control group. After treated with drug or adjuvant injection every 3 weeks for 24 weeks, all rats were sacrificed and total blood were collected. Aorta, renal arteries, and kidney were preserved for functional assay, immunohistochemistry, western blot, and quantitative reverse-transcription polymerase chain reaction. RESULTS In vascular reactivity assays, aorta, intrarenal, and coronary arteries of all three ADT groups showed endothelial dysfunction. AT1R and related molecules at protein and messenger RNA (mRNA) level were tested, and AT1R pathway was shown to be activated and played a role in endothelial dysfunction. Both ACE and AT1R mRNA levels were doubled in the aorta in the leuprolide group while Orx and degarelix groups showed upregulation of AT1R in the kidney tissues. By immunohistochemistry, our result showed higher expression of AT1R in the intrarenal arteries of leuprolide and degarelix groups. The role of reactive oxygen species in endothelial dysfunction was confirmed by DHE fluorescence, nitrotyrosine overexpression, and upregulation of NOX2 in the different ADT treatment groups. CONCLUSION ADT causes endothelial dysfunction in male rats. GnRH receptor agonist compared to GnRH receptor antagonist, showed more impairment of endothelial function in the aorta and intrarenal arteries. Such change might be associated with upregulation and activation of AngII-AT1R-NOX2 induced oxidative stress in the vasculature. These results help to explain the different cardiovascular risks and outcomes related to different modalities of ADT treatment.
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Affiliation(s)
- Jeremy Yuen-Chun Teoh
- S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiao-Yu Tian
- Institute of Vascular Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Christine Yim-Ping Wong
- S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi-Wai Lau
- Institute of Vascular Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Chak-Kwong Cheng
- Institute of Vascular Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Victor Wai-Lun Tang
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China
| | - Ronald Cheong-Kin Chan
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yu Huang
- Institute of Vascular Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi-Fai Ng
- S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
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Ramírez J, Rodriquez D, Qiao F, Warchall J, Rye J, Aklile E, Chiang ASC, Marin BC, Mercier PP, Cheng CK, Hutcheson KA, Shinn EH, Lipomi DJ. Correction to Metallic Nanoislands on Graphene for Monitoring Swallowing Activity in Head and Neck Cancer Patients. ACS Nano 2018; 12:8832. [PMID: 30102517 DOI: 10.1021/acsnano.8b05715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
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Wu CN, Tseng CC, Fanchiang YT, Cheng CK, Lin KY, Yeh SL, Yang SR, Wu CT, Liu T, Wu M, Hong M, Kwo J. High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain. Sci Rep 2018; 8:11087. [PMID: 30038363 PMCID: PMC6056423 DOI: 10.1038/s41598-018-29493-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 07/05/2018] [Indexed: 11/13/2022] Open
Abstract
Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.
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Grants
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 105-2112-M-007-014-MY3 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2112-M-002-010 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
- 106-2622-8-002-001 Ministry of Science and Technology, Taiwan (Ministry of Science and Technology of Taiwan)
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Affiliation(s)
- C N Wu
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Tseng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Y T Fanchiang
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - C K Cheng
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - K Y Lin
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - S L Yeh
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - S R Yang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C T Wu
- National Nano Device Laboratories, Hsinchu, 30013, Taiwan
| | - T Liu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - M Wu
- Department of Physics, Colorado State University, Fort Collins, CO, 80523, USA
| | - M Hong
- Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
| | - J Kwo
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.
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Ramírez J, Rodriquez D, Qiao F, Warchall J, Rye J, Aklile E, Chiang ASC, Marin BC, Mercier PP, Cheng CK, Hutcheson KA, Shinn EH, Lipomi DJ. Metallic Nanoislands on Graphene for Monitoring Swallowing Activity in Head and Neck Cancer Patients. ACS Nano 2018; 12:5913-5922. [PMID: 29874030 PMCID: PMC6286678 DOI: 10.1021/acsnano.8b02133] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
There is a need to monitor patients with cancer of the head and neck postradiation therapy, as diminished swallowing activity can result in disuse atrophy and fibrosis of the swallowing muscles. This paper describes a flexible strain sensor comprising palladium nanoislands on single-layer graphene. These piezoresistive sensors were tested on 14 disease-free head and neck cancer patients with various levels of swallowing function: from nondysphagic to severely dysphagic. The patch-like devices detected differences in (1) the consistencies of food boluses when swallowed and (2) dysphagic and nondysphagic swallows. When surface electromyography (sEMG) is obtained simultaneously with strain data, it is also possible to differentiate swallowing vs nonswallowing events. The plots of resistance vs time are correlated to specific events recorded by video X-ray fluoroscopy. Finally, we developed a machine-learning algorithm to automate the identification of bolus type being swallowed by a healthy subject (86.4%. accuracy). The algorithm was also able to discriminate between swallows of the same bolus from either the healthy subject or a dysphagic patient (94.7% accuracy). Taken together, these results may lead to noninvasive and home-based systems for monitoring of swallowing function and improved quality of life.
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Affiliation(s)
- Julian Ramírez
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Daniel Rodriquez
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Fang Qiao
- Department of Computer Science and Engineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0404, La Jolla, CA 92093-0404
| | - Julian Warchall
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0407, La Jolla, CA 92093-0407
| | - Jasmine Rye
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Eden Aklile
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Andrew S-C. Chiang
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Brandon C. Marin
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
| | - Patrick P. Mercier
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0407, La Jolla, CA 92093-0407
| | - CK Cheng
- Department of Computer Science and Engineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0404, La Jolla, CA 92093-0404
| | - Katherine A. Hutcheson
- Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Unit 1445, 1515 Holcombe St, Houston, TX 77030-4009
| | - Eileen H. Shinn
- Department of Behavioral Sciences, The University of Texas MD Anderson Cancer Center, Unit 1330, 1155 Pressler St, Houston, TX 77230-1439
| | - Darren J. Lipomi
- Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, CA 92093-0448
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Fanchiang YT, Chen KHM, Tseng CC, Chen CC, Cheng CK, Yang SR, Wu CN, Lee SF, Hong M, Kwo J. Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi 2Se 3/yttrium iron garnet heterostructures. Nat Commun 2018; 9:223. [PMID: 29335558 PMCID: PMC5768741 DOI: 10.1038/s41467-017-02743-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [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: 08/26/2017] [Accepted: 12/20/2017] [Indexed: 12/03/2022] Open
Abstract
Harnessing the spin–momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi2Se3/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi2Se3 film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi2Se3/YIG reveals signatures of the magnetic proximity effect of TC as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices. Understanding the effects of topological insulators on magnetization dynamics of adjacent magnetic materials is essential for novel spintronic devices. Here, Fanchiang et al. report thickness dependence of interfacial in-plane magnetic anisotropy and damping enhancement in Bi2Se3/yttrium iron garnet (YIG) bilayers, indicating an important role of topological surface states in the magnetization dynamics of YIG.
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Affiliation(s)
- Y T Fanchiang
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - K H M Chen
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Tseng
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C C Chen
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C K Cheng
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
| | - S R Yang
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - C N Wu
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - S F Lee
- Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
| | - M Hong
- Department of Physics, National Taiwan University, Taipei, 10617, Taiwan.
| | - J Kwo
- Department of Physics, National Tsing Hua University, Hsinchu, 30013, Taiwan.
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Ng L, Chan C, Au T, Cheng CK, Mo KF, Li W, Lei K, Mok T, Ng M, Raghupathy R. Deoxycytidine kinase expression in AML blasts and its relationship to leukemia-free and overall survival: PS101. Porto Biomed J 2017; 2:214. [PMID: 32258705 DOI: 10.1016/j.pbj.2017.07.093] [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: 11/17/2022] Open
Affiliation(s)
- L Ng
- Faculty of Medicine, The Chinese University of Hong Kong (CUHK)
| | - C Chan
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - T Au
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - C K Cheng
- Blood Cancer Cytogenetics and Genomics Laboratory, Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, CUHK, Hong Kong
| | - K F Mo
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - W Li
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - K Lei
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - T Mok
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
| | - M Ng
- Blood Cancer Cytogenetics and Genomics Laboratory, Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, CUHK, Hong Kong
| | - R Raghupathy
- Partner State Key Laboratory of Oncology in South China, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute and Prince of Wales Hospital, CUHK
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Ng MHL, Cheng SH, Lai PBS, Ling KKF, Lau KM, Cheng CK, Wong N, Zee BCY, Lin CK. Association of polymorphism of human leukocyte antigen alleles with development of hepatocellular carcinoma in Hong Kong Chinese. Hong Kong Med J 2012; 18 Suppl 6:37-40. [PMID: 23249853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Affiliation(s)
- M H L Ng
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong SAR, China.
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Cheng CK, Lee CK, Lin CK. Clinically significant red blood cell antibodies in chronically transfused patients: a survey of Chinese thalassemia major patients and literature review. Transfusion 2012; 52:2220-4. [PMID: 22339270 DOI: 10.1111/j.1537-2995.2012.03570.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Red blood cell (RBC) alloimmunization is reported to occur at an incidence of 5.2% to 23.5% among patients with thalassemia requiring chronic transfusion. With very limited data on alloimmunization among the Chinese population, a territory-wide study has been performed to look at its prevalence among Chinese thalassemia major patients. STUDY DESIGN AND METHODS A retrospective study was conducted by reviewing RBC request records for patients with thalassemia major in Hong Kong from 2006 to 2009. Demographic information and serologic data were retrieved for analysis. RESULTS A total of 382 patients were identified and consisted of 190 males and 192 females with a median age of 23 ± 10.4 (range, 0.25 to 52) years. Eighty-eight patients (23.0%) were reported to have RBC antibodies. Of them, 114 alloantibodies, 18 autoantibodies, and 19 unidentified antibodies were identified. Anti-E (42, 39.3%), anti-Mi(a)/Mur (33, 30.85%), anti-c (14, 13.1%), and anti-Jk(a) (seven, 6.55%) were the commonest antibodies reported. However, one case of anti-K (0.9%) and two cases of anti-Fy(b) (1.9%) were reported. Seven of the 18 patients with autoantibodies contained a total of 13 alloantibodies. They were anti-E (five, 38.4%), anti-Mi(a)/Mur (four, 30.8%), anti-Jk(a) (two, 15.4%), anti-c (one, 7.7%), and anti-Fy(b) (one, 7.7%). CONCLUSION It is the first comprehensive study on Chinese thalassemia major patients. Clinically significant alloantibodies are different from those observed in the Western population, although antibodies developed against Rh antigens are still common. Chinese patients are less likely to have antibodies against Kell and Duffy blood group antigens, but are more prone to develop antibodies against the Miltenberger antigens.
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Affiliation(s)
- C K Cheng
- Hong Kong Red Cross Blood Transfusion Service, Hong Kong, China
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Kuriya B, Cheng CK, Chen HM, Bykerk VP. Validation of a prediction rule for development of rheumatoid arthritis in patients with early undifferentiated arthritis. Ann Rheum Dis 2008; 68:1482-5. [DOI: 10.1136/ard.2008.092676] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Objective:To validate a model which predicts progression from undifferentiated arthritis (UA) to RA, in a Canadian UA cohort.Methods:The prediction rule, comprising variables which are scored from 0 to 13, with higher scores reflecting an increased risk of RA, was applied to baseline characteristics of all patients with UA. Progression to RA was determined at 6 months.Results:105 patients were identified. By 6 months, 80 (76%) had developed RA while 25 (24%) had developed another diagnosis. Number of tender and swollen joints, rheumatoid factor positivity, anti-cyclic citrullinated peptide positivity, poor functional status and high disease activity were associated with development of RA (p<0.01). Median prediction score was 8.0 for progressors, 5.0 for non-progressors. With these cut-off points, 18 (72%) patients with scores ⩽5 did not develop RA, while 35 (97%) with scores ⩾8 did develop RA.Conclusions:High scores in our cohort predicted those who progressed to RA by 6 months. Baseline scores ⩾8 corresponded with higher rates of progression.
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Sedaghat H, Wood MA, Cain JW, Cheng CK, Baumgarten CM, Chan DM. Complex temporal patterns of spontaneous initiation and termination of reentry in a loop of cardiac tissue. J Theor Biol 2008; 254:14-26. [PMID: 18571676 DOI: 10.1016/j.jtbi.2008.05.003] [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] [Received: 08/31/2007] [Revised: 03/27/2008] [Accepted: 05/02/2008] [Indexed: 11/17/2022]
Abstract
A two-component model is developed consisting of a discrete loop of cardiac cells that circulates action potentials as well as a pacing mechanism. Physiological properties of cells such as restitutions of refractoriness and of conduction velocity are given via experimentally measured functions. The dynamics of circulating pulses and the pacer's action are regulated by two threshold relations. Patterns of spontaneous initiations and terminations of reentry (SITR) generated by this system are studied through numerical simulations and analytical observations. These patterns can be regular or irregular; causes of irregularities are identified as the threshold bistability (T-bistability) of reentrant circulation and in some cases, also phase-resetting interactions with the pacer.
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Affiliation(s)
- H Sedaghat
- Department of Mathematics and the Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, 23284-2014, USA.
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12
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Zhang X, Tu KN, Chen Z, Tan YK, Wong CC, Mhaisalkar SG, Li XM, Tung CH, Cheng CK. Pulse electroplating of copper film: a study of process and microstructure. J Nanosci Nanotechnol 2008; 8:2568-2574. [PMID: 18572685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Copper films with high density of twin boundaries are known for high mechanical strength with little tradeoff in electrical conductivity. To achieve such a high density, twin lamellae and spacing will be on the nanoscale. In the current study, 10 microm copper films were prepared by pulse electrodeposition with different applied pulse peak current densities and pulse on-times. It was found that the deposits microstructure was dependent on the parameters of pulse plating. Higher energy pulses caused stronger self-annealing effect on grain recrystallization and growth, thus leading to enhanced fiber textures, while lower energy pulses gave rise to more random microstructure in the deposits and rougher surface topography. However in the extremes of pulse currents we applied, the twin densities were not as high as those resulted from the medium or relatively high pulse currents. The highest amount of nanoscale twinning was found to form from a proper degree of self-annealing induced grain structure evolution. The driving force behind the self-annealing is discussed.
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Affiliation(s)
- Xi Zhang
- Department of Materials Science and Engineering, UCLA, Los Angeles, CA 90095-1595, USA
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13
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Abstract
AIMS To establish the longitudinal relationship of foot complications to neuropathy based on a 4-year follow-up of diabetic patients stratified by sudomotor dysfunctions. METHODS One hundred and nineteen Type 2 diabetic patients and 36 non-diabetic subjects were initially registered in the prospective cohort study. Plantar skin temperature and sympathetic skin response (SSR) were used to monitor sympathetic mediated thermoregulation and sudomotor function. Peripheral somatic and central autonomic functions were studied using clinical, nerve conduction and cardiovascular reflex tests. At enrolment, the diabetic patients were classified into one of three groups by the progressive stages of sudomotor dysfunction: SSR+ (SSR present; 49 patients), SSR- (SSR absent; 41 patients) and at-risk group (SSR absent but with cracked skin involving partial thickness of the dermis; 29 patients). RESULTS The at-risk group had 13.4 times (95% confidence interval 1.4-125.7) higher plantar ulceration rates than the other two patient groups during the 4 years. Skin temperature elevation occurred in parallel with development of foot sweating problems. There were no significant differences between the three patient groups in the ratios of abnormal heart rate variation, orthostatic test and clinical neuropathy score at follow-up. After 4 years of follow-up, nerve conduction abnormalities were more frequent in the at-risk and SSR- groups than in the SSR+ group. CONCLUSIONS Early deterioration of small sympathetic fibres could not be quantified accurately by the clinical, somatic and autonomic tests. Assessing skin integrity and sudomotor function in at-risk individuals identifies early peripheral sympathetic neuropathy, even if the patients have no overt clinical symptoms.
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Affiliation(s)
- P C Sun
- Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan
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14
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Wu SH, Chu NK, Liu YC, Chen CK, Tang SFT, Cheng CK. Relationship between the EMG ratio of muscle activation and bony structure in osteoarthritic knee patients with and without patellar malalignment. J Rehabil Med 2008; 40:381-6. [DOI: 10.2340/16501977-0178] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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15
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Abstract
The presence of progesterone response element (PRE) in the 5'-flanking region of the human GnRH receptor (GnRHR) suggests the possible regulation of this gene by progesterone (P). In the present study, we examined the effects of P in transcriptional regulation of human GnRHR gene expression at the pituitary and placenta levels since the GnRHR has been detected in both tissues. By the use of transient transfection assays, a differential regulation of human GnRHR promoter activity by P was observed. P treatment resulted in a decrease in promoter activity in the pituitary alphaT3-1 cells, suggesting a P-mediated inhibitory action. Interestingly, P is found to have a stimulatory role at the placental expression of this gene. Addition of RU486 to, or inhibition of endogenous P production by, the placental JEG-3 cells leads to a decrease in promoter activity, which is reversed by the replacement of P. Further studies have identified a putative PRE, namely human GR-PRE (located between -535 and -521, related to translation start site), that may be responsible for the P action since the mutation of these motifs reversed the P-mediated effects. The binding of PR to this element is confirmed by antibody supershift assays. The physiological effects of P are mediated through two PR isoforms, namely PR-A and PR-B. In the present study, overexpression of human PR-A resulted in a decrease in human promoter activity in both pituitary and placental cells. Interestingly, overexpression of PR-B exhibits a cell-dependent transcriptional activity, whereby it functions as a transcription activator in the placenta but as a transcription repressor in the pituitary. In summary, our results demonstrated a differential usage of PR-A and PR-B in transcriptional regulation of human GnRHR gene expression by P at the pituitary and placenta levels.
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Affiliation(s)
- K W Cheng
- Department of Obstetrics and Gynaecology, The University of British Columbia, Vancouver, British Columbia, Canada V6H 3V5
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16
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Abstract
STUDY DESIGN Magnetic resonance images (MRIs) were used to determine the geometry of the tissues studied. OBJECTIVE To investigate the geometric parameters of tissues around the lumbosacral joint. SUMMARY OF BACKGROUND DATA Cross-sectional area (CSA), moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1), which are important in the study of spinal mechanics and models for the investigation of low back pain. It was insufficient information to describe the relative dimension of spinal tissues except muscles around the lumbar spine. METHODS MRIs from eight asymptomatic young Taiwanese male adults were collected to present CSA, moment arms, and line of action of the tissues located at lumbosacral joint (L5-S1). Four pairs of trunk muscles, erector spinae, rectus abdominis, abdominal oblique externus, and psoas muscles, ligamentum flavum, and facet joints at the bilateral sides were studied. RESULTS Spinal tissues at the level of lumbosacral joint were determined. The CSAs of the spinal elements at the L5-S1 normalized by the CSA of trunk ranged from 5.42% (the erector spinae) to 0.14% (the ligamentum flavum). The moment arm of the spinal elements relative to the trunk width and depth ranged from 40.91% (rectus abdominis at the y direction) to 0.38% (ligamentum flavum at the x direction). The profile of geometric elements of lumbosacral joint in the Asian male subjects was similar to the data collected from the white population. The data also showed that right-left symmetry in the aforementioned dimension. CONCLUSION Normalized data of the CSA, moment arm, and line of action of the spinal tissues at the L5-S1 joint were reported in vivo through the MRI techniques. The profile of geometric elements of lumbosacral joint in the Asian male subjects did not differ from the white population. In addition to muscles, the geometry of facet joint and ligament was determined, which would be important to the calculation of force distribution on the lumbosacral joint.
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Affiliation(s)
- Y H Lin
- Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, Republic of China
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17
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Abstract
We present a case of a ten-month-old boy with Goldenhar's syndrome and significant retrognathia in whom a tracheostomy was performed to relieve upper airway obstruction. Tracheal intubation was facilitated by direct suspension laryngoscopy using a slotted rigid laryngoscope. We propose this technique as an alternative method for tracheal intubation in infants and young children with a difficult airway. The management of the difficult airway in children with Goldenhar's syndrome is discussed.
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Affiliation(s)
- P P Chen
- Department of Anaesthesiology, Intensive Care and Operating Services, Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong
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18
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Abstract
After anterior interbody fusion in the lumbar spine, the accelerated degeneration of the disc adjacent to the fusion levels was clinically observed. To understand the stress distribution of the adjacent disc, this study created a finite element model of the lumbar spine from L1-L5 vertebral body. The fusion model modified from the intact model was used to simulate the anterior interbody fusion. Various loading conditions, which included flexion, extension, lateral bending, and torsion, were applied to the finite element model to study the corresponding stress distribution. From the finite element model calculation, at a lower fusion site or more fusion levels, the stress of the disc adjacent to interbody fusion increased more than upper fusion site or single fusion level under flexion, torsion and lateral bending. Larger stress increase was estimated at the upper disc adjacent to interbody fusion than the lower disc adjacent to interbody fusion. In stress distribution, the upper disc adjacent to interbody fusion had a little alteration under torsion.
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Affiliation(s)
- C S Chen
- Orthopaedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang-Ming University, 155 Sec 2, Li-Nung St, Shih-Pai, Taipei, Taiwan
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Cheng CK, Kanamaru T, Ueno N, Tanaka KI, Idei Y, Nishida Y, Yamamoto M. A case of pancreatic serous cystadenoma obstructing the distal pancreatic duct. Oncol Rep 2001; 8:811-3. [PMID: 11410789 DOI: 10.3892/or.8.4.811] [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: 11/06/2022] Open
Abstract
We present a case of resected serous cystadenoma of the pancreas inducing marked dilatation of the main distal pancreatic duct. A 68-year-old woman, previously diagnosed with chronic pancreatitis, presented with upper abdominal pain. Abdominal US revealed a highly echoic mass in the pancreas. A CT scan disclosed a low density mass in the pancreas and dilatation of the main peripheral pancreatic duct. The mass demonstrated homogeneous and high signal intensity on T2-weighted magnetic resonance imaging (MRI). Selective abdominal arteriography showed the mass strained by the celiac artery. The tumor markers were CEA (2.4 ng/ml) and CA19-9 (6.1 U/ml). After the diagnosis of serous cystadenoma of the pancreas, the patient underwent distal pancreatectomy and splenectomy. The tumor (2.5 cm in diameter) consisted of grayish-white nodules and occupied the body of the pancreas. The tail of the pancreas was atrophic. Histopathological examination of the specimen showed a multilocular lesion containing numerous cysts with the inner surfaces evenly lined by one layer of cuboid or flat epithelial cells which stained positive for periodic acid-Schiff (PAS), evidencing serous cystadenoma. The patient is doing quite well one and a half years after the operation.
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Affiliation(s)
- C K Cheng
- Department of Surgery, Kobe Rosai Hospital, Kagoike-dori 4-1-23, Kobe-city, Hyogo 651-0053, Japan
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20
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Liau JJ, Hu CC, Cheng CK, Huang CH, Lo WH. The influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics. Clin Biomech (Bristol, Avon) 2001; 16:160-6. [PMID: 11222935 DOI: 10.1016/s0268-0033(00)00040-1] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To investigate the influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics. DESIGN A finite element analysis was used to investigate the alteration of contact characteristics of the tibiofemoral joint due to inserting a pressure sensitive film between the contacting surfaces. BACKGROUND The discrepancy between actual contact behaviors of tibiofemoral joint of knee prosthesis and the measurement using Fuji pressure sensitive film was not discussed extensively. The change of direct contact circumstance of the tibiofemoral joint due to inserting a pressure sensitive film was not well reported. METHOD A two-dimensional finite element model of the tibiofemoral joint of knee prosthesis in the sagittal plane was constructed. Four different radii of the femoral component were used to investigate the conformity effect. Two-layers of plane strain element were used to model the pressure sensitive film. The influence of inserting a pressure sensitive film on the actual contact characteristics was analyzed by comparing the results of the change in contact radius. RESULTS Inserting a pressure sensitive film between contacting surfaces would disturb the original contact behaviors, especially in the lowest conformity design. The maximum difference of contact radius between the model simulating actual contact circumstance and the model with inserting a pressure sensitive film between contacting surface was 77% in the lowest conformity condition at the smallest load. CONCLUSIONS This study proposes a quantitative analysis of contact characteristics in the tibiofemoral joint of knee prosthesis between the models with and without inserting a pressure sensitive film into the contact surface. The measurement of contact area in artificial tibiofemoral joints by using Fuji pressure sensitive film is always overestimated its true contact area by 14-77%. RELEVANCE This study revealed the measurement of contact characteristics of artificial tibiofemoral joints by using Fuji pressure sensitive film which depends on not only the applied load, but also the conformity and material properties of the contact surface. Therefore, the information of the conformity and material properties of the contact surface should be provided as well as the applied load wherever a measurement of contact characteristics using Fuji pressure sensitive film is analyzed and interpreted.
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Affiliation(s)
- J J Liau
- Orthopaedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang Ming University, No. 155, Sec. 2, Li-Nung St., Shih-Pai, ROC, Taipei, Taiwan
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Abstract
BACKGROUND The purpose of this study was to evaluate the effectiveness of PEG in the adsorption of autoantibodies and the detection of alloantibodies in patients with warm autoimmune hemolytic anemia (WAIHA). STUDY DESIGN AND METHODS The study was divided into three parts. First, the effectiveness of antibody removal by a conventional adsorption procedure and that by the PEG adsorption method were compared by using commercial antisera adsorbed with antigen-positive RBCs. Second, patients' sera with known weak alloanti-E were used to test against screening cells after allogeneic adsorption to show nonspecific coating of antibodies and the dilution effect on the PEG adsorption procedure. Third, conventional and PEG one-cell sample allogeneic adsorptions of WAIHA patients' sera with and without alloantibodies were performed and compared. RESULTS In the first part, seven of the eight polyclonal antisera gave a lower titer and score when tested against antigen-positive RBCs in the indirect antiglobulin test; this indicated that PEG is more efficient in removing antibodies. In the second part, similar reaction patterns were observed in antibody screening tests on unadsorbed sera and on sera after the first, second, and third adsorptions, which indicated that there was no alloantibody loss, nonspecific antibody coating, or dilution effect when PEG was added in the allogeneic adsorption procedures. In the third part, a 40-percent increase in efficiency in reducing the number of adsorptions and an 85-percent decrease in completion time of the adsorption procedures were obtained when PEG was used for adsorbing sera from 16 patients with WAIHA. Both conventional and PEG procedures were capable of removing autoantibodies to identify the specificities of alloantibodies. CONCLUSION The PEG adsorption method is an effective, sensitive, and efficient method of enhancing auto- antibody adsorption and alloantibody detection. It can reduce the processing time and minimize the delay of urgent transfusions to patients with WAIHA and can indirectly enhance cost-effectiveness and decrease the labor-intensive testing required by these cases.
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Affiliation(s)
- C K Cheng
- Hematology Section, Department of Pathology, Queen Elizabeth Hospital, Howlon, Hong Kong
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22
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Abstract
Dynamic models of the behavior of solvent and solute molecules can be made using cellular automata. A chromatographic column was represented by use of a cellular automata grid of 43 x 200 spaces. Solvent (mobile phase), solute and stationary phase cells were designated to simulate the chromatographic situation. The movements of solute and solvent cells down the grid were monitored for different numbers of iterations, different flow rates and different affinities of the solutes for the stationary phase and the solvent for itself. The cellular automata dynamics were successfully able to model expected chromatographic behavior except in a few cases where the number of cells was not large enough to provide an average value reflective of the molecular situation.
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23298, USA
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23
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Abstract
OBJECTIVE To improve the simulation of the task of manual materials handling for Chinese laborers, this study estimated the inertial properties of Chinese adults by using magnetic resonance imaging. DESIGN Magnetic resonance imaging was used as a means of estimating inertial property. Following the estimation of inertial properties for the Chinese subjects, comparison between estimates for Chinese and Caucasian populations was made. BACKGROUND Estimates of segment inertial properties are frequently based on data and procedures developed from human cadaver studies in which inertial properties have been measured directly. The errors might be derived from the utilization of the Caucasian data were questioned in our previous study on the spinal force prediction of the Chinese subjects during manual lifting. METHODS Magnetic resonance images were scanned at a 20 mm interval from eight males aged 26 (S.D., 4) years. Tissues were differentiated and verified using adequate intensity thresholds on each slice, and the segmental volume and mass were integrated by slices. The moments of inertia for each segment were then determined about the anatomical axes using the parallel axis theorem.Results. Results showed that our estimates were close to the data derived by Dempster with a slight deviation. Larger percentages of mass were found in the upper arm (4.0%) and thigh (13.6%) than in previous studies. On the other hand, smaller moments of inertia about three axes were noted in the shank. CONCLUSION Biomechanical modeling of the human body requires accurate prediction of body segment parameters that include measures of volume, mass, center of mass, and moments of inertia. This study suggests the need to estimate the inertial properties of segments from the Chinese population. Application of the data may improve the simulation of the task of manual materials handling for Chinese laborers in the future studies. RELEVANCE Biomechanical modeling of the human body requires accurate prediction of body segment parameters that include measures of volume, mass, center of mass, and moments of inertia. To obtain the basic data of segment parameters for the Chinese adults, this study was proceeded with the magnetic resonance imaging technique.
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Affiliation(s)
- C K Cheng
- Institute of Biomedical Engineering, National Yang-Ming University, 112, Taipei, Taiwan, ROC.
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Young TH, Cheng CK, Lee YM, Chen LY, Huang CH. Analysis of ultrahigh molecular weight polyethylene failure in artificial knee joints: thermal effect on long-term performance. J Biomed Mater Res 2000; 48:159-64. [PMID: 10331909 DOI: 10.1002/(sici)1097-4636(1999)48:2<159::aid-jbm10>3.0.co;2-1] [Citation(s) in RCA: 16] [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] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The mechanism resulting in damage to and failure of ultrahigh molecular weight polyethylene (UHMWPE) tibial inserts was investigated on clinically retrieved components. The severity of the subsurface damage increased with the length of time that the component had been implanted. A theoretical analysis was developed to account for the generation of subsurface damage based on a heat transfer model. Friction generates surface heat during articulation of total knee systems. Due to the cooling effect of body fluid on the surface, the rise in temperature on the UHMWPE surface is lower than that below the surface. The peak temperature was estimated to occur on a plane positioned about 1 to 2 mm below the surface. This result was similar to the bulk temperature variation observed during in vivo and in vitro studies by other investigators. Although the difference in temperature on and below the surface is only a few degrees, the thermal effect becomes apparent after a long time and may be explained by the viscoelastic behavior of polymers: the temperature-time equivalence. It is therefore suggested that this thermal effect is another contributory factor to material damage, in addition to high stress and oxidative degradation (in appropriate cases). Therefore, any technological efforts aimed at improving the performance of artificial joint prostheses should minimize the thermal effects at the subsurface of the articular components.
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Affiliation(s)
- T H Young
- Graduate Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei, Republic of China
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25
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Abstract
An anticipatory system has been modeled using the dynamic characteristics of cellular automata. Rules governing the steps in an enzymatic conversion of substrates to products are operative in the system. A concentration of an intermediate product influences the creation of a supplemental enzyme that enhances the competence of an enzyme down stream. This anticipation of the future event creates a condition in which the concentration of a later substrate is suppressed, a property characteristic of the system. The model presents a useful opportunity to study a variety of aspects of this fascinating phenomena.
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond 23298, USA.
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Abstract
This paper describes the use of kinematic, asynchronous, stochastic cellular automata to model liquid properties, solution phenomena and kinetic phenomena encountered in complex biological systems. Cellular automata models of dynamic phenomena represent in silico experiments designed to assess the effects of competing factors on the physical and chemical properties of solutions and other complex systems. Specific applications include solution behavior, separation of immiscible liquids, micelle formation, diffusion, membrane passage, first- and second-order chemical kinetics, enzyme activity and acid dissociation. Cellular automata is thus considered as providing an exploratory method for the analysis of dynamic phenomena and the discovery and understanding of new, unexpected phenomena.
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond 23298, USA
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Liau JJ, Cheng CK, Huang CH, Lee YM, Chueh SC, Lo WH. The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. Clin Biomech (Bristol, Avon) 1999; 14:717-21. [PMID: 10545626 DOI: 10.1016/s0268-0033(99)00027-3] [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: 02/07/2023]
Abstract
OBJECTIVE To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. DESIGN An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well. METHODS Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component. RESULTS The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses. CONCLUSIONS This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses. RELEVANCE This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.
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Affiliation(s)
- J J Liau
- Orthopaedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang Ming University, No. 155, Sec. 2, Li-Nung Street, Shih-Pai, Taipei 11221, Taiwan, ROC
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Abstract
From 1991 to 1996, 953 cases of porous-coated anatomic modular knee prostheses with all-polyethylene patellar components were implanted. Among them, 4 cases had breakage of the patellar component at the peg-button interfaces. One had loosening of the patellar component by cutting out the patellar bony bed. Heavy body weight, weakness of the pegs of the all-polyethylene patellar component, and osteonecrosis of the patella were conceived as the causes of failure.
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Affiliation(s)
- C H Huang
- Department of Orthopaedic Surgery, Mackay Memorial Hospital, Taipei, Taiwan, ROC
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29
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Abstract
The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical roundness of outer shells and inner heads of the bipolar prostheses were measured before the experiments. The acetabulum and outer shell of the bipolar prostheses were fixed on a Bionix 858 material testing system axially by separate fixation tools. The axial load of 1,400 N and 2,800 N was than applied on the specimen. The axis was rotated from 0 degrees to 90 degrees at the speed of 1 degree/s. All 3 outer shells were tested to this paired acetabulum randomly and separately. The frictional torque on the outer bearing surface of the different prostheses was recorded by the material testing system. The frictional torque on the inner bearing surface was also measured by the same procedure as was done for the outer bearing. The final results were statistically compared by the 1-way analysis of variance test method. Bipolar prostheses of the UHR system showed the largest frictional torque on outer bearing when it was loaded with 1,400 N and 2,800 N. The final results showed that all the bipolar prostheses had ideal motion behavior when functioning under the loading of 1,400 N. The frictional torque on the inner bearing was found to be larger than the frictional torque on the outer bearing in some prostheses when the loading was increased to 2,800 N. Thus, the bipolar endoprostheses functioned as unipolar prostheses. The only relative motion remained between the outer bearing surface and the acetabulum. This effect causes complications, such as implant protrusion in the acetabulum.
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Affiliation(s)
- C Y Lung
- Orthopaedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, ROC
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Luh JJ, Chang GC, Cheng CK, Lai JS, Kuo TS. Isokinetic elbow joint torques estimation from surface EMG and joint kinematic data: using an artificial neural network model. J Electromyogr Kinesiol 1999; 9:173-83. [PMID: 10328412 DOI: 10.1016/s1050-6411(98)00030-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Because the relations between electromyographic signal (EMG) and anisometric joint torque remain unpredictable, the aim of this study was to determine the relations between the EMG activity and the isokinetic elbow joint torque via an artificial neural network (ANN) model. This 3-layer feed-forward network was constructed using an error back-propagation algorithm with an adaptive learning rate. The experimental validation was achieved by rectified, low-pass filtered EMG signals from the representative muscles, joint angle and joint angular velocity and measured torque. Learning with a limited set of examples allowed accurate prediction of isokinetic joint torque from novel EMG activities, joint position, joint angular velocity. Sensitivity analysis of the hidden node numbers during the learning and testing phases demonstrated that the choice of numbers of hidden node was not critical except at extreme values of those parameters. Model predictions were well correlated with the experimental data (the mean root-mean-square-difference and correlation coefficient gamma in learning were 0.0290 and 0.998, respectively, and in three different speed testings were 0.1413 and 0.900, respectively). These results suggested that an ANN model can represent the relations between EMG and joint torque/moment in human isokinetic movements. The effect of different adjacent electrode sites was also evaluated and showed the location of electrodes was very important to produce errors in the ANN model.
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Affiliation(s)
- J J Luh
- Department of Electrical Engineering, National Taiwan University, Taipei, Republic of China
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Abstract
Fracture of the femoral component associated with polyethylene wear and osteolysis after total knee arthroplasty (TKA) has not been well reported before. A 63-year-old man with osteoarthritis of the right knee underwent TKA with a New Jersey LCS Knee, with cementing on the tibia and patella but not on the femoral component. After 42 months, in addition to wearing of polyethylene of the tibia and patella, severe osteonecrosis of the medial femoral condyle was noted. Osteonecrosis caused loss of osseous support of the medial flange of the femoral component, and the bone ingrowth of the central and lateral flange to the distal femur was so good that it overcame the yield stress of the metal of the femoral component and caused fracture of the femoral component. The osteolytic area was filled with autogenous iliac bone, and a new femoral component was inserted and cemented. The patient's condition became satisfactory with relief of pain. Although uncommon, fracture of the femoral component does occur associated with polyethylene wear and osteolysis.
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Affiliation(s)
- C H Huang
- Department of Orthopaedic Surgery, Mackay Memorial Hospital, Taipei, Taiwan, ROC
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32
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Cheng CK, Chen HH, Chen CS, Lee SJ. Influences of walking speed change on the lumbosacral joint force distribution. Biomed Mater Eng 1999; 8:155-65. [PMID: 10065882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
To more understand the influence of the walking speed on the spinal joint force distribution, a three-dimensional biomechanical model was used to estimate the spine loads during human gait with three different walking speeds. This previously developed and validated model included a dynamic external model and an internal model with forces of disc, 8 major muscles, 2 ligaments and 2 facet joints at L5/S1 level. A linear optimization method was used to solve the internal model to estimate the L5/S1 spinal joint force distribution. The results of five young male subjects showed that the mean peak L5/S1 disc compressive forces on the slow, preferred and fast speeds were 2.28, 2.53, 2.95 body weight, respectively. The peak forces happened right after the heel strike and before completely toe off. The facet joint forces were generally increased with the walking speed increase, too. To reduce the loads on the spine, the slow walking is then recommended for the patients with low back pain or after spinal surgery.
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Affiliation(s)
- C K Cheng
- Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan, ROC
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33
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Abstract
OBJECTIVE To improve the design of the knee prosthesis, a new technique to design the tibial baseplate of total knee prostheses was developed. METHODS One senior surgeon operated on 79 osteoarthrosis patients by using PCA total knee prostheses for total knee replacement. Four dimensions were measured intraoperatively and compared, including the anterioposterior length and the mediolateral width of the resected tibia plateau and implant. The data of anterioposterior length and the mediolateral width of resected surfaces of the tibial plateau of the 79 patients were plotted in a coordinate system. This coordinate system was formed with the mediolateral width as the x-axis and anterioposterior length as the y-axis. A circle, 5 mm in diameter, was used as the maximum coverage criterion. Five contemporary products and a new design product were used to screen the data to see how many patients would fall within the criteria. From the results of the screened data, we calculated the coverage percentage of the patients. RESULTS The ratio of the anterioposterior length to the mediolateral width of the resected surfaces of the tibial plateau was greater than that of the ratio of the PCA prostheses (P < 0.05). The results showed that no single product on the market had the patients meet over 70% of the criterion. A different ratio of the anterioposterior length to the mediolateral width was designed to achieve 90% coverage of the patients that met the criterion. DISCUSSION One possible explanation for the discrepancy between resected surfaces and implants is that the osteoarthrosis patients developed knee deformities that changed the surface of the tibial plateau and thus altered the knee dimensions. Since the total knee prostheses were used on osteoarthrosis patients, the dimensions of the resected tibial surfaces of osteoarthrosis patients should be considered in the design of the tibial baseplate of total knee prostheses.
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Affiliation(s)
- C K Cheng
- Orthopaedic Biomechanics Laboratory, National Yang Ming University, Republic of China
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34
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Abstract
From 1984 to 1987, a complete, single-layered, porous-coated femoral component (Roy-Camille type) was used for primary cementless total hip replacement in 80 patients. Seventy-two patients (77 hips) with a minimal follow-up of 5 years (mean 7.2 years) were assessed clinically and radiographically. Thigh pain occurred in 4 hips. Osteolysis appeared in 5 hips. Cortical thinning around the femoral component was significant at the proximal and middle levels. In total, 6 femoral components failed, which led to reoperation due to aseptic loosening (4 hips) and septic loosening (2 hips). The hip rating score (modified d'Aubigne and Postel rating system) in the surviving hips progressed from 9.0 (range 6-10) preoperatively to 16.3 (range 12-18) points at the latest follow-up. From this study, we found that the complete, single-layered, porous-coated stem had a low loosening rate after 5 years. Bone ingrowth into the porous coating was found in most of the cases. A lower stress shielding effect in comparison with the complete, multi-layered, porous-coated prosthesis was also noted.
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Affiliation(s)
- C H Chen
- Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Kweishan, Taoyuan, Taiwan
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Abstract
A cross-sectional study of 679 Alzheimer's disease patients from thirteen sites in nine states provides a unique opportunity to estimate costs of Alzheimer's disease care by disease stage and care setting and to explore potential areas of cost savings. In 1996 annual costs of caring for patients with mild, moderate, and severe Alzheimer's disease were $18,408, $30,096, and $36,132, respectively. Monthly savings of $2,029 in formal services are possible if disease progression can be slowed. Annual institutional cost savings of $9,132 also are achievable if alternative residential settings are used.
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Affiliation(s)
- J Leon
- Center for Health Affairs (CHA), Bethesda, MD, USA
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36
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Abstract
One of the most controversial issues in total knee arthroplasty is whether to retain or sacrifice the posterior cruciate ligament (PCL). Investigators have used various methods to evaluate the influence of the PCL after total knee arthroplasty, but muscle strength evaluation has not been reported. The purpose of this study is to compare the long-term effects of PCL retention or sacrifice on muscle strength. Isokinetic testings and isometric testings were studied in patients with three different types of prosthesis design: total condylar, low contact stress rotating platform (both sacrifice PCL), and low contact stress meniscal bearing (retains PCL). The results showed that in all testing conditions, the hamstring to quadriceps ratios did not significantly differ among the three prosthetic designs (P > .05) even after long-term (6-13 years) functional adaptation.
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Affiliation(s)
- C H Huang
- Department of Orthopaedic Surgery, Mackay Memorial Hospital, and Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, Republic of China
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37
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Jan MH, Wang SF, Cheng CK, Chen CY, Sullivan PE. Gain of muscle torque at low and high speed after isokinetic knee strengthening program in healthy young and older adults. J Formos Med Assoc 1998; 97:339-44. [PMID: 9610058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Low-speed isokinetic exercise has been recommended to exert a maximal contraction and produce greater muscle torque than high-speed exercise in young adults. The purpose of this study was to compare the effectiveness of low- and high-speed isokinetic exercise programs for increasing muscle torque in young and elderly people. Twenty healthy elderly and 20 young subjects participated. The elderly subjects were divided into two groups. One group performed high-speed (300 degrees/s) isokinetic exercise training three times a week for the dominant-side knee extensor and low-speed (60 degrees/s) exercise for the non-dominant side for 6 weeks. The other group was trained using the reverse exercise regime. The training program for the young subjects was the same as that for the elderly groups. All subjects had their knee extensor torque evaluated with an isokinetic test before and at 2-week intervals during the training program. For young and elderly groups, both high- and low-speed isokinetic exercise training increased extensor torque in low- and high-speed tests. For the young group, low-speed exercise effectively improved muscle torque at low and high speeds. The improvement in slow muscle torque was significantly greater than that in fast muscle torque. For the elderly subjects, high-speed isokinetic exercise produced the greatest muscle torque at high speed in the first 2 weeks of training, and demonstrated a sharp increase in muscle torque in the final 2 weeks. Low-speed exercise frequently caused knee stress and the inability of some elder subjects to continue the exercises with maximal effort. Our findings indicate that high-speed exercise may be more appropriate for the elderly, and low-speed exercise may be more appropriate for younger people.
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Affiliation(s)
- M H Jan
- School of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan
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38
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Abstract
From January 1985 to December 1990, 598 consecutive New Jersey low-contact stress (LCS) total knee arthroplasties (TKAs) were performed for gonarthrosis. Among these 598 operations, 322 were with rotating platform elements and 276 were with meniscal bearing elements. During 5 to 8 years of follow-up, eight knees had severe symptomatic polyethylene failure that required revision surgery; all eight cases were meniscal bearing types. The failed polyethylene inserts were retrieved and studied. It was observed that there were four probable failure mechanisms associated with the catastrophic polyethylene wear. First, insufficient thickness of the meniscal bearing was the major reason for wear. Second, the malpositioning of the metal tibial tray in the transverse plane resulted in the breaking of the meniscal bearing. Third, the inability of the patellar to rotate due to tissue ingrowth made the polyethylene break. Last, yellowing of the subsurface of the meniscal bearing was a sign of polyethylene failure. These four possible failure mechanisms are all associated with the design of the meniscal bearing type of LCS knee prostheses. Therefore, it is suggested that the design of the LCS knee prosthesis should be modified.
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Affiliation(s)
- C H Huang
- Department of Orthopaedic Surgery, Mackay Memorial Hospital, Taipei, Taiwan, R.O.C
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39
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Lin CK, Mak KH, Cheng CK, Yang CP. The first case of the p phenotype in a Gurkha Nepalese. Immunohematology 1998; 14:30-2. [PMID: 15377211] [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: 04/30/2023]
Abstract
A serum sample from a Gurkha Nepalese soldier, residing in Hong Kong, was found to cause hemolysis of reagent ABO red cells (RBCs) in the reverse blood grouping test. Subsequent follow-up studies revealed that he was of the p phenotype, with potent anti-PP1Pk that was strongly hemolytic both at room temperature and 37 degrees C. The anti-PP1Pk was composed of IgG and IgM, and its various components were separable.
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Affiliation(s)
- C K Lin
- Hong Kong Red Cross Blood Transfusion Service, 15 King's Park Rise, Kowloon, Hong Kong
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40
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Kang WJ, Shiu JR, Cheng CK, Lai JS, Tsao HW, Kuo TS. The effect of electrode arrangement on spectral distance measures for discrimination of EMG signals. IEEE Trans Biomed Eng 1997; 44:1020-3. [PMID: 9311170 DOI: 10.1109/10.634653] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The proper electrode placement in applying cepstral coefficients for electromyogram (EMG) signature discrimination was investigated. We measured EMG signals of different motions with two electrode arrangements simultaneously. Electrode pairs were located separately on dominant muscles (S-type arrangement) and closely in the region between muscles (C-type arrangement). The application of the cepstral method to signals derived from a C-type arrangement did not achieve the same discrimination as with a S-type arrangement. We used a simplified model to elucidate the poor performance in C-type signals. The bandwidth of signals obtained from S-type placement is wider than that from C-type. Narrower bandwidth decreases the importance of the more discriminative parts for both autoregressive (AR) and cepstral methods. The cepstral method is more sensitive to such variation, so the degradation in performance is more serious for the cepstral method. Second, the amplitude of C-type signal is lower than the S-type; therefore, the C-type signal is more sensitive to the disturbance of noise, especially in the high-frequency band. As high-frequency noise increases, the spectral difference between different EMG signals is gradually dominated by the low-frequency part, which is more informative. Thus, the performances of both methods are improved with increasing high-frequency noise. The improving rate of the AR method is faster than the cepstral method; therefore, its discriminative efficiency may exceed the cepstral method with C-type arrangement.
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Affiliation(s)
- W J Kang
- Department of Electrical Engineering, National Taiwan University, Taipei, R.O.C
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41
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Abstract
A cellular automata model of a solute diffusing in water has been created and studied for the influential attributes. The results with this model are in agreement with experimental results; that is, that lipophilic solutes diffuse faster than do polar solutes. The model reveals that a solution composed of a relatively lipophilic solute permits a greater extent of diffusion of another solute. This observation is in agreement with the model showing a diffusion preference of a solute between two solutions made up of differing polarities. The solute diffuses farther into the lipophilic solution. A temperature-lipophilicity phase diagram shows the influence of these two attributes on the rate of diffusion. A model of diffusion through solutions containing stationary ingredients reveals a faster rate when the ingredient is lipophilic. We are led to a conclusion that the relative lipophilicity of solutes or stationary ingredients in a solution has a direct influence on the rates of diffusion of other solutes in their midst.
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond 23298, USA
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42
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Shyu JC, Hsieh YS, Chang CL, Tsai CC, Cheng CK, Liu JY. Change in protein kinase C activity on day 5 of decidualization in pseudopregnant rats. CHINESE J PHYSIOL 1997; 40:107-12. [PMID: 9303248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The specific activities of protein kinase C (PKC) and protein tyrosine kinase (PTK) were determined in the decidualized uterine tissue of pseudopregnant rat on day 5 of decidualization. We found that the activity of the cytosolic PKC was significantly lower in decidualized uterine tissue as compared with that of the controlateral untreated uterine tissues (1.5 +/- 1.4 versus 57.5 +/- 4.1 pmol 32P/min/mg, P < 0.001), while the PKC activity in particulate fraction was not significantly different (124.8 +/- 14.5 versus 236.8 +/- 88.6 pmol 32P/min/mg) concerning protein concentration. The reduced expression of the cytosolic PKC activity was observed on all five individual rats. In contrast, the decidualized uterine tissue showed similar cytosolic PTK activity as compared with the controlateral untreated uterine tissues (20.1 +/- 3.0 versus 20.6 +/- 3.2 pmol 32P/min/mg protein), and similar in particulate PTK activity (42.5 +/- 9.0 versus 36.8 +/- 5.1 pmol 32P/min/g protein). These results indicate that cytosolic PKC activity may be involved in modulation of decidual growth.
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Affiliation(s)
- J C Shyu
- Department of Physiology, Chung Shan Medical and Dental College, Taichung, Taiwan, ROC
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43
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Chang GC, Luh JJ, Liao GD, Lai JS, Cheng CK, Kuo BL, Kuo TS. A neuro-control system for the knee joint position control with quadriceps stimulation. IEEE Trans Rehabil Eng 1997; 5:2-11. [PMID: 9086380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A neuro-control system was designed to control the knee joint to move in accordance with the desired trajectory of movement through stimulation of quadriceps muscle. This control system consisted of a neural controller and a fixed parameter proportional-integral-derivative (PID) feedback controller, which was designated as a neuro-PID controller. A multilayer feedforward time-delay neural network was used and trained as an inverse model of the functional electrical stimulation (FES)-induced quadriceps-lower leg system for direct feedforward control. The training signals for neural network learning were obtained from experimentation using a low-pass filtered random sequence to reveal the plant characteristics. The Nguyen-Widrow method was used to initialize the neural connection weights. The conjugate gradient descent algorithm was then used to modify these connection weights so as to minimize the errors between the desired outputs and the network outputs. The knee joint angle was controlled with only small deviations along the desired trajectory with the aid of the neural controller. In addition, the PID feedback controller was utilized to compensate for the residual tracking errors caused by disturbances and modeling errors. This control strategy was evaluated on one able-bodied and one paraplegic subject. The neuro-PID controller showed promise as a position controller of knee joint angle with quadriceps stimulation.
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Affiliation(s)
- G C Chang
- Department of Electrical Engineering, National Taiwan University, R.O.C
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44
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Abstract
To establish and compare the relationship between standing balance and walking performance, eight children with spastic diplegic cerebral palsy (CP) and 16 non-disabled, age- and sex-matched children were studied. The results showed that the children with CP had worse static balance stability in various sensory environments and dynamic balance (rhythmic shifting ability) than the non-disabled children. Moreover, the children with CP walked at a slower speed but at a greater physiological cost than the non-disabled children. In the children with CP, dynamic balance significantly correlated with walking function. It is suggested that rhythmic weight-shift training should be encouraged to improve the walking performance of children with CP.
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Affiliation(s)
- H F Liao
- School of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Republic of China
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45
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Cheng CK, Yao NK, Liu HC. Weight bearing influence on knee joint bony contact movements: an in vivo video-fluoroscopy study. Proc Natl Sci Counc Repub China B 1997; 21:20-5. [PMID: 9208483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In order to understand the effects of body weight-bearing on knee joint bony contact movements, a video-fluoroscopic digitizing system with in vivo human knee extension-flexion motions of 12 healthy adults under body weight-bearing and non-weight-bearing conditions was studied. These 12 subjects were equally separated into two groups consisting of a body weight-bearing group and a non-weight-bearing group. Video-fluoroscopic images were digitized to get three parameters from the knee joint bony geometry. These three parameters were the radius of rotation, the are length of rotation, and the contact point of the tibiofemoral joint, and they were used to decide the knee joint bony contact status of the sliding, spinning and rocking motions. The results showed that the knee bony contact movements under body weight-bearing conditions had about 4 times the incidence rate of the sliding motion under non-weight-bearing conditions. The incidence rate of the sliding motion was greatest when the knee flexion was less than 30 degrees. The knee bony contact movements under non-weight-bearing conditions had a larger spinning motion incidence rate and smaller rocking motion incidence rate than they did under weight-bearing conditions. The larger spinning motion incidence rate when the knee joint flexion was greater than 60 degrees. In conclusion, the body weight-bearing factor should be considered in studying knee joint bony contact movements.
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Affiliation(s)
- C K Cheng
- Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, R.O.C
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46
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Berger AS, Cheng CK, Pearson PA, Ashton P, Crooks PA, Cynkowski T, Cynkowska G, Jaffe GJ. Intravitreal sustained release corticosteroid-5-fluoruracil conjugate in the treatment of experimental proliferative vitreoretinopathy. Invest Ophthalmol Vis Sci 1996; 37:2318-25. [PMID: 8843916] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE Proliferative vitreoretinopathy (PVR) remains the most common cause of failed retinal detachment (RD) surgery. The authors compared the effectiveness of two intraocular sustained-release codrugs in suppressing PVR in a rabbit model a surgically implantable pellet releasing 5-fluorouracil (FU) and dexamethasone (DX) for 1 week and an injectable intravitreal sustained-release suspension releasing 5-FU and triamcinolone acetonide for 1 month. METHODS Sustained-release devices and suspensions were prepared to deliver equimolar quantities of corticosteroid and 5-FU. In group 1, devices were implanted surgically into the vitreous of the right eye of 10 New Zealand White rabbits. Ten control rabbits received surgical implantation of the suture only. In group 2, drug suspension was injected into the vitreous of the right eye of 10 New Zealand White rabbits. Ten control rabbits received injection of the vehicle only. One day later, each rabbit was injected intravitreally with 250,000 homologous rabbit dermal fibroblasts. Severity of PVR was graded clinically by two masked observers on days 3, 7, 10, 14, 21, and 28. RESULTS In group 1, clinical severity of PVR was less in the experimental group than in the control group at all time points, this was only statistically significant on day 10 (P = 0.04). Six eyes developed moderate to severe tractional RD or bullous RD in the control group by day 10 compared with none in the experimental group (P = 0.01). In group 2, the median clinical grading of eyes in the experimental group was significantly less than that in the control group at all time points through day 21 (P < or = 0.01). CONCLUSIONS Both the intravitreal sustained-release dexamethasone-5-FU device and the triamcinolone-5-FU suspension effectively inhibit the progression of PVR in a rabbit model. Simultaneous delivery of 5-FU and corticosteroid may target different components of the wound-healing process in this disease.
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Affiliation(s)
- A S Berger
- Department of Ophthalmology, Duke University, Durham, North Carolina, USA
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47
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Chang GC, Kang WJ, Luh JJ, Cheng CK, Lai JS, Chen JJ, Kuo TS. Real-time implementation of electromyogram pattern recognition as a control command of man-machine interface. Med Eng Phys 1996; 18:529-37. [PMID: 8892237 DOI: 10.1016/1350-4533(96)00006-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [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: 02/02/2023]
Abstract
The purpose of this study was to develop a real-time electromyogram (EMG) discrimination system to provide control commands for man-machine interface applications. A host computer with a plug-in data acquisition and processing board containing a TMS320 C31 floating-point digital signal processor was used to attain real-time EMG classification. Two-channel EMG signals were collected by two pairs of surface electrodes located bilaterally between the sternocleidomastoid and the upper trapezius. Five motions of the neck and shoulders were discriminated for each subject. The zero-crossing rate was employed to detect the onset of muscle contraction. The cepstral coefficients, derived from autoregressive coefficients and estimated by a recursive least square algorithm, were used as the recognition features. These features were then discriminated using a modified maximum likelihood distance classifier. The total response time of this EMG discrimination system was achieved about within 0.17 s. Four able bodied and two C5/6 quadriplegic subjects took part in the experiment, and achieved 95% mean recognition rate in discrimination between the five specific motions. The response time and the reliability of recognition indicate that this system has the potential to discriminate body motions for man-machine interface applications.
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Affiliation(s)
- G C Chang
- Department of Electrical Engineering, National Taiwan University, Taipei, ROC
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48
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry and Mathematical Sciences, Virginia Commonwealth University, Richmond, USA
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49
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Abstract
The activity of protein kinase C (PKC) in human liver cancer and adjacent normal liver tissue was determined. It was found that the activity of the membrane-bound PKC was significantly decreased in cancer tissue compared with that of the adjacent normal tissues (245.3 +/- 49.3 versus 396.9 +/- 82.4 pmol 32P/min per mg, P < 0.05); while the PKC activity in the cytosolic fraction was not significantly different (50.6 +/- 11.3 versus 40.0 +/- 6.6 pmol 32P/min per mg) concerning protein concentration. The reduced expression of membrane-bound PKC activity was observed at least in 8 of 9 patients. Moreover, the cancer tissue showed a significant decrease in total membranous PKC activity compared with the adjacent normal tissue of each patient (163.1 +/- 38.8 versus 433.8 +/- 92.4 pmol 32P/min per g tissue; P < 0.005) and no difference in total cytosolic PKC activity (285.9 +/- 58.8 versus 311.6 +/- 44.0 pmol 32P/min per g tissue). These results indicate that the progression of the human liver cancer might be associated with the decrease of membrane-bound PKC activity.
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Affiliation(s)
- K J Chang
- Department of Surgery, College of Medicine, National Taiwan University, Taipei, ROC
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50
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Abstract
We have developed a cellular automata model of an enzyme reaction with a substrate in water. The model produces Michaelis-Menten kinetics with good Lineweaver-Burk plots. The variation in affinity parameters predicts that, in general, hydrophobic substrates are more reactive with enzymes, this attribute being more important than the relationship between enzyme and substrate. The ease of generation and the illustrative value of the model lead us to believe that cellular automata models have a useful role in the study of dynamic phenomena such as enzyme kinetics.
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Affiliation(s)
- L B Kier
- Department of Medicinal Chemistry and Mathematical Sciences, Virginia Commonwealth University, Richmond 23298, USA
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