Insulin-Like Growth Factors Promote Vasculogenesis in Embryonic Stem Cells

The ability of embryonic stem cells to differentiate into endothelium and form functional blood vessels has been well established and can potentially be harnessed for therapeutic angiogenesis. However, after almost two decades of investigation in this field, limited knowledge exists for directing endothelial differentiation. A better understanding of the cellular mechanisms regulating vasculogenesis is required for the development of embryonic stem cell-based models and therapies. In this study, we elucidated the mechanistic role of insulin-like growth factors (IGF1 and 2) and IGF receptors (IGFR1 and 2) in endothelial differentiation using an embryonic stem cell embryoid body model. Both IGF1 or IGF2 predisposed embryonic stem to differentiate towards a mesodermal lineage, the endothelial precursor germ layer, as well as increased the generation of significantly more endothelial cells at later stages. Inhibition of IGFR1 signaling using neutralizing antibody or a pharmacological inhibitor, picropodophyllin, significantly reduced IGF-induced mesoderm and endothelial precursor cell formation. We confirmed that IGF-IGFR1 signaling stabilizes HIF1α and leads to up-regulation of VEGF during vasculogenesis in embryoid bodies. Understanding the mechanisms that are critical for vasculogenesis in various models will bring us one step closer to enabling cell based therapies for neovascularization

DEVELOPMENT OF SUPERPLASTICITY IN 8090 AL-LI ALLOY BY STATIC RECRYSTALLIZATION

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Differential reactivity of nitro-substituted monolayers to electron beam and X-ray irradiation

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Interface roughness effect between gate oxide and metal gate on dielectric property

We report a simple theoretical model based on experimental data about the interface roughness effect between gate oxide and metal gate on dielectric. From the analytic approach, we confirm that the increase in interface roughness generates the decrease in the dielectric constant as well as the increase in the leakage current. We checked the interface roughness effect between high-kappa HfO2 gate oxides and Ru gates by atomic layer deposition (ALD) and physical vapor deposition (PVD). The ALD Ru gate showed better dielectric properties (high dielectric constant and low leakage current) and lower interface roughness than the PVD Ru metal gate. (C) 2009 Elsevier B.V. All rights reserved.X111111sciescopu

Selective cleavage of nitro groups in nitro-substituted aromatic monolayers by synchrotron soft X-rays: Effect of molecular structure on cleavage rates

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Undetactable levels of genotoxicity of SiO2 nanoparticles in in vitro and in vivo tests [Erratum]

Kwon JY, Kim HL, Lee JY, et al. Int J Nanomedicine. 2014;9(Suppl 2):173–181.The title of the paper “Undetactable levels of genotoxicity of SiO2 nanoparticles in in vitro and in vivo tests” should read “Undetectable levels of genotoxicity of SiO2 nanoparticles in in vitro and in vivo tests”.Read the original articl

Undetactable levels of genotoxicity of SiO2 nanoparticles in in vitro and in vivo tests

Jee Young Kwon,1,* Hye Lim Kim,1,* Jong Yun Lee,2 Yo Han Ju,2 Ji Soo Kim,2 Seung Hun Kang,1 Yu-Ri Kim,3 Jong-Kwon Lee,4 Jayoung Jeong,4 Meyoung-Kon Kim,3 Eun Ho Maeng,2 Young Rok Seo1 1Department of Life Science, Institute of Environmental Medicine, Dongguk University, Seoul, 2Korea Testing and Research Institute, 3Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul, 4Toxicological Research Division, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Chungcheongbuk-do, Republic of Korea *These authors contributed equally to this work and should be considered co-first authors Background: Silica dioxide (SiO2) has been used in various industrial products, including paints and coatings, plastics, synthetic rubbers, and adhesives. Several studies have investigated the genotoxic effects of SiO2; however, the results remain controversial due to variations in the evaluation methods applied in determining its physicochemical properties. Thus, well characterized chemicals and standardized methods are needed for better assessment of the genotoxicity of nanoparticles.Methods: The genotoxicity of SiO2 was evaluated using two types of well characterized SiO2, ie, 20 nm (-) charge (SiO2EN20(-)) and 100 nm (-) charge (SiO2EN100(-)). Four end point genotoxicity tests, ie, the bacterial mutation assay, in vitro chromosomal aberration test, in vivo comet assay, and in vivo micronucleus test, were conducted following the test guidelines of the Organization for Economic Cooperation and Development (OECD) with application of Good Laboratory Practice.Results: No statistically significant differences were found in the bacterial mutation assay, in vitro chromosomal aberration test, in vivo comet assay, and in vivo micronucleus test when tested for induction of genotoxicity in both two types of SiO2 nanoparticles.Conclusion: These results suggest that SiO2 nanoparticles, in particular SiO2EN20(-) and SiO2EN100(-), are not genotoxic in both in vitro and in vivo systems under OECD guidelines. Further, the results were generated in accordance with OECD test guidelines, and Good Laboratory Practice application; it can be accepted as reliable information regarding SiO2-induced genotoxicity. Keywords: genotoxicity test, Organization for Economic Cooperation and Development test guideline, Good Laboratory Practice, silica dioxid