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252. Terahertz Time Domain Spectroscopy of Rat Skin Tissues

Author

Fan, Shuting ECE, Parrott, Edward, Wang, Yi-Xiang, Pickwell-macpherson, Emma, Fan, Shuting ECE, Parrott, Edward, Wang, Yi-Xiang, and Pickwell-macpherson, Emma

Abstract

Terahertz time domain spectroscopy has been used to characterize various tissues in biomedical research to date. In this paper the terahertz properties of three groups of rat skin tissues treated with different injections (normal saline control, high dose of Dotarem, and high dose of Omniscan) are measured. The difference in terahertz properties of the tissues can be clearly observed from the results. © 2013 IEEE.

Published
2013

254. Revivals of Zitterbewegung in the Bernevig—Hughes—Zhang model in the quantum spin Hall regime with a laser pulse

Author

Wu Ya-Min and Wang Yi-Xiang

Subjects
Physics, symbols.namesake, Hall effect, Quantum mechanics, Dirac equation, symbols, General Physics and Astronomy, Zitterbewegung, Landau quantization, Electron, Spin (physics), Electromagnetic radiation, Magnetic field
Abstract

We theoretically investigate the Zitterbewegung (ZB) behavior of electrons in the Bernevig—Hughes—Zhang model with a short laser pulse. To obtain a steady picture, we fix the electron on the Landau levels with a magnetic field. The ZB motion and the electromagnetic radiations in the quantum spin Hall regime are given. We find that over a shorter time, the electromagnetic radiations show a quasi-classical cyclotron oscillation, while over a longer time, they exhibit a clear revival picture. The resulting revival time and excited electric field are large enough to make experimental detection accessible.

Published
2014

255. Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines

Author

Zhu,Xiao-Ming, Wang,Yi-Xiang J, Leung,Ken Cham-Fai, Lee,Siu-Fung, Zhao,Feng, Wang,Da-Wei, Lai,Josie MY, Wan,Chao, Cheng,Christopher HK, Ahuja,Anil T, Zhu,Xiao-Ming, Wang,Yi-Xiang J, Leung,Ken Cham-Fai, Lee,Siu-Fung, Zhao,Feng, Wang,Da-Wei, Lai,Josie MY, Wan,Chao, Cheng,Christopher HK, and Ahuja,Anil T

Abstract

Xiao-Ming Zhu1, Yi-Xiang J Wang1, Ken Cham-Fai Leung2,3, Siu-Fung Lee2, Feng Zhao1, Da-Wei Wang2, Josie MY Lai4, Chao Wan4, Christopher HK Cheng4, Anil T Ahuja11Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR; 2Institute of Molecular Functional Materials and Department of Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR; 3Institute of Creativity and Department of Chemistry, The Hong Kong Baptist University, Kowloon Tong, Kowloon, Hong Kong SAR; 4School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong KongPurpose: To compare the cellular uptake efficiency and cytotoxicity of aminosilane (SiO2-NH2)-coated superparamagnetic iron oxide (SPIO@SiO2-NH2) nanoparticles with three other types of SPIO nanoparticles coated with SiO2 (SPIO@SiO2), dextran (SPIO@dextran), or bare SPIO in mammalian cell lines.Materials and methods: Four types of monodispersed SPIO nanoparticles with a SPIO core size of 7 nm and an overall size in a range of 7–15 nm were synthesized. The mammalian cell lines of MCF-7, MDA-MB-231, HT-29, RAW264.7, L929, HepG2, PC-3, U-87 MG, and mouse mesenchymal stem cells (MSCs) were incubated with four types of SPIO nanoparticles for 24 hours in the serum-free culture medium Dulbecco’s modified Eagle’s medium (DMEM) with 4.5 µg/mL iron concentration. The cellular uptake efficiencies of SPIO nanoparticles were compared by Prussian blue staining and intracellular iron quantification. In vitro magnetic resonance imaging of MSC pellets after SPIO labeling was performed at 3 T. The effect of each SPIO nanoparticle on the cell viability of RAW 264.7 (mouse monocyte/macrophage) cells was also evaluated.Results: Transmission electron microscopy demonstrated surface coating with SiO2-NH2, SiO2, and dextran prevented SPIO nanoparticle aggregation in DMEM culture medium. MCF-7, MDA-MB-231

Published
2012

256. A promising diagnostic method: Terahertz pulsed imaging and spectroscopy

Author

Sun, Yiwen, Sy, Ming Yiu, Wang, Yi-Xiang J., Ahuja, Anil T., Zhang, Yuan-Ting, Pickwell-MacPherson, E., Sun, Yiwen, Sy, Ming Yiu, Wang, Yi-Xiang J., Ahuja, Anil T., Zhang, Yuan-Ting, and Pickwell-MacPherson, E.

Abstract

The terahertz band lies between the microwave and infrared regions of the electromagnetic spectrum. This radiation has very low photon energy and thus it does not pose any ionization hazard for biological tissues. It is strongly attenuated by water and very sensitive to water content. Unique absorption spectra due to intermolecular vibrations in this region have been found in different biological materials. These unique features make terahertz imaging very attractive for medical applications in order to provide complimentary information to existing imaging techniques. There has been an increasing interest in terahertz imaging and spectroscopy of biologically related applications within the last few years and more and more terahertz spectra are being reported. This paper introduces terahertz technology and provides a short review of recent advances in terahertz imaging and spectroscopy techniques, and a number of applications such as molecular spectroscopy, tissue characterization and skin imaging are discussed.

Published
2011

257. Investigating the Role of Water Content on the Terahertz Properties of Rat Liver Cirrhosis

Author

Sy, M.Y., Huang, Shengyang, Wang, Yi-xiang, Ahuja, Anil T., Zhang, Yuan-Ting, Pickwell-Macpherson, Emma, Sy, M.Y., Huang, Shengyang, Wang, Yi-xiang, Ahuja, Anil T., Zhang, Yuan-Ting, and Pickwell-Macpherson, Emma

Abstract

Existing studies terahertz pulsed imaging and spectroscopy to be safe techniques for biomedical applications. Coherent detection in terahertz pulsed imaging enable it to probe a wide range of information of unknown objects in both time and frequency domains. These distinctive features have recently spurred numerous research into human and animal tissues. We previously reported the dielectric properties of normal and diseased rat liver tissues by terahertz pulsed imaging. In this study, further experiments were carried out to understand the observed differences in the optical parameters by looking into the water contents of the normal and cirrhotic specimen.

Published
2010

263. Calcitriol restores renovascular function in estrogen-deficient rats through downregulation of cyclooxygenase-2 and the thromboxane-prostanoid receptor

Author

Dong, Jinghui, primary, Ling Wong, Siu, additional, Wai Lau, Chi, additional, Liu, Jian, additional, Wang, Yi-Xiang, additional, Dan He, Zhen, additional, Fai Ng, Chi, additional, Yu Chen, Zhen, additional, Yao, Xiaoqiang, additional, Xu, Aimin, additional, Ni, Xiaochen, additional, Wang, Hongyan, additional, and Huang, Yu, additional

Published
2013
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268. TO THE EDITOR

Author

Wang, Yi-Xiang, primary, Griffith, James F., additional, and Yuan, Jing, additional

Published
2013
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269. Folate-conjugated Fe3O4@SiO2@gold nanorods@mesoporous SiO2 hybrid nanomaterial: a theranostic agent for magnetic resonance imaging and photothermal therapy

Author

Wang, Da-Wei, primary, Zhu, Xiao-Ming, additional, Lee, Siu-Fung, additional, Chan, Ho-Man, additional, Li, Hung-Wing, additional, Kong, Siu Kai, additional, Yu, Jimmy C., additional, Cheng, Christopher H. K., additional, Wang, Yi-Xiang J., additional, and Leung, Ken Cham-Fai, additional

Published
2013
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270. Evaluation of Glycosaminoglycan in the Lumbar Disc Using Chemical Exchange Saturation Transfer MR at 3.0 Tesla: Reproducibility and Correlation with Disc Degeneration.

Author

DENG, Min, YUAN, Jing, CHEN, Wei Tian, CHAN, Queenie, GRIFFITH, James F, and WANG, Yi Xiang

Subjects
GLYCOSAMINOGLYCANS, REPRODUCIBLE research, MAGNETIZATION transfer, SAGITTAL curve, NUCLEUS pulposus
Abstract

Objective This study aims to explore the clinical applicability and relevance of glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) for intervertebral disc. Methods 25 subjects ranging in age from 24 yrs to 74 yrs were enrolled. gagCEST was acquired using a single-slice TSE sequence on a 3T. Saturation used a continuous rectangular RF pulse with B 1 =0.8 μT and a fixed duration time =1100 ms. Sagittal image was obtained firstly without saturation pulse, and then saturated images were acquired at 52 offsets ranging from ±0.125 to ±7 parts per million (ppm). MR T2 relaxivity map was acquired at the identical location. Six subjects were scanned twice to assess scan-rescan reproducibility. Results GagCEST intraclass correlation coefficient (ICC) of six subjects was 0.759 for nucleus pulposus (NP) and 0.508 for annulus fibrosus (AF). Bland-Altman plots showed NP had a mean difference of 0.10% (95% limits of agreement: −3.02% to 3.22%); while that of AF was 0.34% (95% limits of agreement: −2.28% to 2.95%). For the 25 subjects, gag CEST in NP decreased as disc degeneration increased, with a similar trend to T2 relaxivity. Gag CEST of AF showed a better correlation with disc degeneration than T2 relaxivity. Conclusion GagCEST in NP and AF decreased as disc degeneration increased, while gagCEST in AF showed a better correlation than T2 relaxivity. [ABSTRACT FROM AUTHOR]

Published
2016
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271. Tip relaxation time in brain regions increases with ageing: an experimental MRI observation in rats.

Author

FENG ZHAO, JING YUAN, GANG LU, ZHANG, LI H., CHEN, ZHI Y., and WANG, YI-XIANG J.

Subjects
NEURODEGENERATION, MAGNETIC resonance imaging of the brain, BRAIN, AGING, ANIMAL models in research, HYPERTENSION, MEDICAL statistics
Abstract

Objective: Tip variation is associated with neurodegenerative diseases. This study aims to observe Tip relaxation time changes in rat brains associated with normal ageing in Sprague-Dawley (SD) rats, Wistar Kyoto (WKY) rats and spontaneously hypertension rats (SHRs). Methods: 18 male SD rats, 11 male WKY rats and 11 male SHRs were used. Tip measurement was performed at 3-T MR with a spin-lock frequency of 500 Hz. SD rats were scanned at the ages of 5, 8. 10 and 15 months. SHRs and WKY rats were scanned at the ages of 6, 9 and 12 months. Results: For SD rats, Tip at the thalamus, hippocampus and frontal cortices increased significantly from 5 to 15 months (p<0.05). For the WKY rats and SHRs, the Tip values in the thalamus, hippocampus and frontal cortices also increased significantly from 6 to 12 months (p <0.05). Furthermore, Tip in the thalamus, hippocampus and frontal cortices of SHRs were consistently higher than those of WKY rats at the ages of 6, 9 and 12 months (p< 0.05). The percentage regional Tip differences between WKY rats and SHRs did not change during ageing. Conclusion: An increase in Tip was associated with agerelated changes of the rat brain. Advances in knowledge: An age-related and hypertensionrelated Tip increase in rat brain regions was observed in the thalamus, hippocampus and frontal cortical regions of the rat brain. [ABSTRACT FROM AUTHOR]

Published
2016
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277. Dipeptidyl Peptidase 4 Inhibitor Sitagliptin Protects Endothelial Function in Hypertension Through a Glucagon–Like Peptide 1–Dependent Mechanism

Author

Liu, Limei, primary, Liu, Jian, additional, Wong, Wing Tak, additional, Tian, Xiao Yu, additional, Lau, Chi Wai, additional, Wang, Yi-Xiang, additional, Xu, Gang, additional, Pu, Yunfei, additional, Zhu, Zhiming, additional, Xu, Aimin, additional, Lam, Karen S.L., additional, Chen, Zhen Yu, additional, Ng, Chi Fai, additional, Yao, Xiaoqiang, additional, and Huang, Yu, additional

Published
2012
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286. DL-3-n-Butylphthalide, an Anti-Oxidant Agent, Prevents Neurological Deficits and Cerebral Injury Following Stroke per Functional Analysis, Magnetic Resonance Imaging and Histological Assessment

Author

Zhang, Lihong, primary, Amy Yu, Wan-hua, additional, J. Wang, Yi-Xiang, additional, Wang, Chunmei, additional, Zhao, Feng, additional, Qi, Wei, additional, M. Chan, W., additional, Huang, Yin, additional, S.M. Wai, Maria, additional, Dong, Jinghui, additional, and T. Yew, D., additional

Published
2012
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290. Photocytotoxicity and Magnetic Relaxivity Responses of Dual-Porous γ-Fe2O3@meso-SiO2 Microspheres

Author

Xuan, Shou-hu, primary, Lee, Siu-Fung, additional, Lau, Janet Ting-Fong, additional, Zhu, Xiaoming, additional, Wang, Yi-Xiang J., additional, Wang, Feng, additional, Lai, Josie M. Y., additional, Sham, Kathy W. Y., additional, Lo, Pui-Chi, additional, Yu, Jimmy C., additional, Cheng, Christopher H. K., additional, and Leung, Ken Cham-Fai, additional

Published
2012
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292. Oxidative Stress-Dependent Cyclooxygenase-2-Derived Prostaglandin F2α Impairs Endothelial Function in Renovascular Hypertensive Rats

Author

Tian, Xiao Yu, primary, Wong, Wing Tak, additional, Leung, Fung Ping, additional, Zhang, Yang, additional, Wang, Yi-Xiang, additional, Lee, Hung Kay, additional, Ng, Chi Fai, additional, Chen, Zhen Yu, additional, Yao, Xiaoqiang, additional, Au, Chak Leung, additional, Lau, Chi Wai, additional, Vanhoutte, Paul M., additional, Cooke, John P., additional, and Huang, Yu, additional

Published
2012
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294. Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity

Author

Zhu, Xiao-Ming, primary, Yuan, Jing, additional, Leung, Ken Cham-Fai, additional, Lee, Siu-Fung, additional, Sham, Kathy W. Y., additional, Cheng, Christopher H. K., additional, Au, Doris W. T., additional, Teng, Gao-Jun, additional, Ahuja, Anil T., additional, and Wang, Yi-Xiang J., additional

Published
2012
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295. Lumbar degenerative spondylolisthesis epidemiology: A systematic review with a focus on gender-specific and age-specific prevalence

Author

Wang, Yi Xiang J., Káplár, Zoltán, Deng, Min, and Leung, Jason C.S.

Abstract

The epidemiology of lumbar degenerative spondylolisthesis (DS) remains controversial. We performed a systematic review with the aim of gaining a better understanding of the prevalence of DS in the general population. The results showed that the prevalence of DS is very gender- and age-specific. Few women and men develop DS before they are 50 years old. After 50 years of age, both women and men begin to develop DS, with women having a faster rate of development than men. For elderly Chinese (≥ 65 years, mean age: 72.5 years), large population-based studies MsOS (Hong Kong, females: n=2000) and MrOS (Hong Kong, males: n=2000) showed DS prevalence was 25.0% in women and 19.1% in men. The female:male (F:M) prevalence ratio was 1.3:1. The published data for MsOS (USA) and MrOS (USA) studies seem to show that elderly Caucasian Americans have a higher DS prevalence, being approximately 60–70% higher than elderly Chinese; however, the F:M prevalence ratio was similar to the elderly Chinese population. Patient data showed that female patients more often received surgical treatment than male and preliminary data showed the ratio of female to male patients receiving surgical treatment did not differ between Northeast Asians (Chinese, Japanese, and Korean), Europeans, and American Caucasians, being around 2:1 in the elderly population. The existing data also suggest that menopause may be a contributing factor for the accelerated development of DS in postmenopausal women.

Published
2017
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297. Menopause as a potential cause for higher prevalence of low back pain in women than in age-matched men

Author

Wang, Yi Xiang J.

Abstract

Female sex hormones play an important role in the aetiology and pathophysiology of a variety of musculoskeletal degenerative diseases. Postmenopausal women show accelerated disc degeneration due to relative oestrogen deficiency, resulting in narrower intervertebral disc space in women than age-matched men, increased prevalence of spondylolisthesis, and increased prevalence of facet joint osteoarthritis. Postmenopausal women also show higher osteoporosis related spine fracture rate, particularly at the thoracic–lumbar junction site. I propose the concept that low back pain (LBP) is more prevalent in postmenopausal women than age-matched men and is associated with the physiological changes caused by the relatively lower level of sex hormones after menopause in women. Considering hormone replacement treatment (HRT)'s consistent efficacy reported with menopause-associated osteoarthritis, an in-depth understanding of the role of the gonadal hormones in LBP modulation warrants further study. HRT initiated at early postmenopausal phase may be protective for recurring LBP. If this is the case, further cost–benefit analysis should be performed for optimal HRT regimen in cases of women with high risk of recurring severe LBP.

Published
2017
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298. Ultra-high loading of sinoporphyrin sodium in ferritin for single-wave motivated photothermal and photodynamic co-therapyElectronic supplementary information (ESI) available. See DOI: 10.1039/c7bm00302a

Author

HuangThese authors contributed equally to this study., Chao, Chu, Chengchao, Wang, Xiaoyong, Lin, Huirong, Wang, Junqing, Zeng, Yun, Zhu, Wenzhen, Wang, Yi-Xiang J., and Liu, Gang

Abstract

In this work, a potent photosensitizer, sinoporphyrin sodium (DVDMS), was loaded into RGD-modified ferritin (R-Fn) nanocages by a rapid, scalable and versatile approach for imaging guided photodynamic and photothermal (PTT/PDT) co-therapy. The resulting nanocomposite formed a well-defined nanocage with a photosensitizer loading capacity as high as 66.67 wt%, which far exceeds those reported previously. The bioengineered protein nanocage-based nanotheranostics exhibits a remarkably improved tumor treatment effect over DVDMS with good biocompatibility and the potential of clinical translation.

Published
2017
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