Xiaoyuan Chen

Bio: Xiaoyuan Chen is an academic researcher from National University of Singapore. The author has contributed to research in topics: Physics & Photothermal therapy. The author has an hindex of 149, co-authored 994 publications receiving 89870 citations. Previous affiliations of Xiaoyuan Chen include Brown University & University of Southern California.

Integrin-targeted imaging and therapy with RGD4C-TNF fusion protein.

Abstract: This study used integrin alpha v beta3 as a target for tumor-specific delivery of tumor necrosis factor-alpha (TNF). The fusion protein RGD4C-TNF bound specifically to alpha v beta3 as evidenced by cell receptor binding assay and noninvasive micro-positron emission tomography imaging. 64Cu-DOTA-RGD4C-TNF had significantly higher activity accumulation in integrin-positive tumors (U87MG and MDA-MB-435) but not in integrin-negative tumors (C6) compared with 64Cu-DOTA-TNF. The magnitude of tumor uptake of 64Cu-DOTA-RGD4C-TNF correlated well with the alpha v beta3 level (U87MG > MDA-MB-435 > C6). Tumor accumulation of 64Cu-DOTA-RGD4C-TNF could be effectively blocked by c(RGDyK) peptide in alpha v beta3-positive tumor models, suggesting alpha v beta3 specificity of RGD4C-TNF fusion protein in vivo. Furthermore, although the fusion of RGD4C moiety to TNF had little effect on the bioactivity and cytotoxicity of RGD4C-TNF compared with TNF in cell culture, RGD4C-TNF was significantly more potent than TNF in inhibiting orthotopic MDA-MB-435 tumor growth. Ex vivo tissue staining confirmed specific cytotoxicity of RGD4C-TNF against integrin-positive tumor cells and tumor vasculature.

Assessment and comparison of magnetic nanoparticles as MRI contrast agents in a rodent model of human hepatocellular carcinoma

Abstract: The purpose of this study was to synthesize, characterize and tailor the surface properties of magnetic nanoparticles with biocompatible copolymer coatings and to evaluate the efficiency of the resulting nanoconjugates as magnetic resonance imaging (MRI) contrast agents for liver imaging. Magnetic nanoparticles with core diameters of 10 and 30 nm were synthesized by pyrolysis and were subsequently coated with a copolymer containing either carboxyl (SHP) or methoxy groups as termini. All four formulas, and ferumoxides (Feridex I.V.®), were individually injected intravenously into separate, normal Balb/C mice (at 2.5, 1.0 and 0.56 mg Fe kg−1), and the animals underwent T2-weighted MRI at multiple time points post injection (p.i.) to evaluate the hepatic uptake and clearance. Furthermore, we compared the abilities of the new formulas and Feridex to detect tumors in an orthotropic Huh7 tumor model. Transmission electron microscopy (TEM) revealed a narrow size distribution of both the 10 and 30 nm nanoparticles, in contrast to a wide size distribution of Feridex. MTT, apoptosis and cyclin/DNA flow cytometry assays showed that the polymer coated nanoparticles had no adverse effect on cell growth. Among all the tested formulas, including Feridex, SHP-30 showed the highest macrophage uptake at the in vitro level. In vivo MRI studies on normal mice confirmed the superiority of SHP-30 in inducing hypointensities in the liver tissue, especially at clinical dose (0.56 mg Fe kg−1) and 3 T field. SHP-30 showed better contrast-to-noise ratio than Feridex on the orthotropic Huh7 tumor model. SHP-30 was found to be an efficient contrast agent for liver MR imaging. The success of this study suggests that, by improving the synthetic approach and by tuning the surface properties of IONPs, one can arrive at better formulas than Feridex for clinical practice. Copyright © 2012 John Wiley & Sons, Ltd.

Micro-PET Imaging of α v β 3 -Integrin Expression with 18 F-Labeled Dimeric RGD Peptide

Abstract: The αv integrins, which act as cell adhesion molecules, are closely involved with tumor invasion and angiogenesis. In particular, αvβ3 integrin, which is specifically expressed on proliferating end...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Chemistry and properties of nanocrystals of different shapes.

Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102