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In Vitro Study on Different Cell Response to Spherical Hydroxyapatite Nanoparticles




Hydroxyapatite (HA) is widely used in filling of bone defects and coating on metal parts of prosthetic implants due to its excellent biocompatibility, bioactivity, and bone-bonding properties. It has been demonstrated that micro-sized HA particles cause inflammatory reaction, especially for the needle shaped particles. However, little effort has been concentrated on the cell responses of the spherical HA nanoparticles. The aim of the present work is to chemically and physically characterize the synthesized HA nanoparticles and to investigate the in vitro cell responses. X-ray diffraction, electron microscopy, nitrogen adsorption, and Fourier transform infrared spectroscopy revealed that the particles consisted of nearly spherical crystallites of carbonate-substituted HA with size of 20—40 nm and specific surface area of 75 m2/g. L929 cell proliferation experiments demonstrate that the spherical HA nanoparticles is more biocompatible than commercially available HA. On the other hand, U2-OS cell test results show that the inhibition rate of the spherical HA nanoparticles increases with time and concentration. The half effective inhibitory concentration (IC50) of the nanoparticles was determined to be 50.8 µg/mL at 72 h. All these data indicated that the synthesized spherical nanocrystalline HA particles can function as an effective biomaterial for bone tumorectomy repair, while having little adverse effect.




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Axus Technology Delivers Multi-Zone Process Control on Micrel CMP Tool
IPEC 472 Equipped with ViPRR™ Carrier Technology Delivers Leading Edge Process Capability Axus Technology announced the recent delivery of an IPEC 472 CMP tool equipped with the Strasbaugh ViPRR™ carrier upgrade to Micrel in San Jose, California. The ViPRR carrier upgrade provides IPEC tool users with leading-edge carrier technology for use on their proven IPEC production tools. After having installed more than four hundred ViPRR carriers on Strasbaugh CMP tools, Strasbaugh selected Axus Technology to design the ViPRR carrier upgrade kit for installation on IPEC CMP tools. The resulting ViPRR carrier upgrade significantly extends the useful life of users' CMP equipment. "The IPEC 472 together with the ViPRR carrier upgrade, will enable Micrel to enhance its multi-zone CMP process control technology," stated Guy Gandenberger, Vice President of Wafer Fab & Foundry Operations for Micrel. "The solution promises to be a cost-effective strategy for upgrading our legacy CMP tools without the significant expense of additional capital equipment." The Strasbaugh ViPRR upgrade kit was introduced several months ago and has now been installed in multiple production facilities. Mike Kirkpatrick, vice president of sales at Strasbaugh noted, "The IPEC ViPRR upgrade is being evaluated by several users and was recently selected by one user for installation on more than a dozen IPEC 472 tools. The outstanding process results seen in fabs and in our product demonstrations have led to increasing interest by IPEC tool owners." The ViPRR upgrade kit was designed to be installed without making any structural or software changes to the IPEC tools. "We focused on creating an upgrade that met all of the mechanical interface requirements for metrology and wafer handling, without making any changes to the tool software." said Dan Trojan, vice president of engineering at Axus. "The ViPRR upgrade improves performance without changing the tool operation." The ViPRR upgrade kit is available on tools provided by Axus Technology or as a field retrofit provided by Strasbaugh.
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[Biochemistry and Molecular Biology] Curcumin Modulates SDF-1{alpha}/CXCR4-Induced Migration of Human Retinal Endothelial Cells (HRECs)

purpose. The stromal-derived factor (SDF)-1 and the CXC receptor (CXCR)-4 jointly regulate the trafficking of various cell types and play a pivotal role in cell migration, proliferation, and survival. The purpose of this study was to assess whether curcumin inhibits human retinal endothelial cell (HREC) migration by interfering with SDF-1/CXCR4 signaling.

methods. Primary HREC culture was established and maintained in endothelial growth medium. The viability and proliferation of HRECs were assessed by MTT and thymidine uptake assays, respectively. The effect of SDF-1–induced HREC migration (chemotaxis) in the presence and absence of curcumin was determined using the Boyden chamber migration assay. Intracellular Ca2+ concentration was measured by fluorometric analysis. Immunofluorescence and Western blot analyses were performed to quantify CXCR4, phosphorylated AKT, and PI3-kinase expression levels.

results. HREC migration increased in a dose-dependent manner (1, 10, 50, and 100 ng/mL; P < 0.001) in SDF-1–treated cells. In contrast, AMD3100, an inhibitor of CXCR4 effectively inhibited HREC migration dose dependently. HREC migration was decreased when the cells were exposed to EGTA, a chelator of Ca2+. Curcumin also blocked Ca2+ influx, an important signal for HREC migration. In addition, curcumin significantly (P < 0.001) decreased SDF-1–induced HRECs migration and downregulated SDF-1–induced expression of CXCR4, phospho-AKT, phospho-phosphatidylinositol-3-kinase (PI3-K), and eNOS.

conclusions. This study indicates that curcumin has an inhibitory effect on SDF-1–induced HREC migration. The plausible mechanism of action could be upstream blockage of Ca2+ influx and the downstream reduction of PI3-K/AKT signals.

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Chromosomal Laboratories Appoints R. Vincent Miller, Ph.D., Vice President And Chief Technical Officer
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UCLA Center to Present World Festival of Sacred Music
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Heads-up study of hair dynamics may lead to better hair-care products
rom frizzy perms to over-bleached waves, "bad hair days" could soon become a less frequent occurrence. Chemists report the first detailed microscopic analysis of what happens to individual hair fibers when they interact with each other, an advance in knowledge key to the development of improved shampoos, conditioners, and other products for repairing damaged hair, the researchers say. (2008-08-18)
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Journal of Biomaterials Applications
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