Biomedical subjects
Publications and source records attributed to Zhi-Xin Guo.
The first actuator based on multiwalled carbon nanotube (MWNT) hydrogels was developed through simple hydrogelation with poly(vinyl alcohol) (PVA). This actuator exhibited excellent actuating properties compared with the corresponding actuator based on poly(acrylic acid)/PVA hydrogels.
Strong luminescence emissions over a broad wavelength region were detected from well-dispersed carbon nanotubes in most functionalized samples, even with excitation wavelengths into the near-IR. Apparently, the better dispersion and functionalization of the nanotubes resulted in more intense luminescence emissions. These emissions may logically be attributed to the trapping of excitation energy by defect sites in the nanotube structure, which are passivated upon the appropriate functionalization of the nanotubes. Better functionalization improves not only the nanotube dispersion (thus diminishing the quenching due to intertube interactions) but also the surface passivation to make the energy trapping sites more emissive, leading to stronger luminescence emissions. Because of such high sensitivity, the visible luminescence emissions may prove valuable in the evaluation of dispersion in functionalized carbon nanotube samples and related nanocomposite materials.
Salvia miltiorrhiza Bunge, a traditional Chinese herbal medicine, is often used for prevention and treatment of cardiovascular disorders such as atherosclerosis. To understand its mechanism of pharmacological action, its effects on endothelial monolayer permeability are studied. The present study demonstrated that extract of S. miltiorrhiza (ESM) and its major ingredients, Danshensu (DSS) and salvianolic acid B (Sal B), inhibited tumor necrosis factor (TNF-alpha) induced endothelial permeability, whereas the other major ingredient, protocatechualdehyde, was ineffective. ESM, DSS and Sal B also repressed expression of vascular endothelial growth factor (VEGF) and extracellular signal-regulated kinase (ERK) activation in TNF-alpha induced HUVEC cells. Furthermore, it was found that ESM attenuated the disorganization of vascular endothelial (VE)-cadherin induced by TNF-alpha. The effect of ESM on TNF-alpha induced endothelial permeability and redistribution of VE-cadherin is likely due to a reduction of VEGF protein expression as a result of modulation of the ERK signaling pathway. Endothelial cell hyperpermeability is implicated in inflammation and subsequent ischemic reperfusion injury and atherosclerosis. Data from this study suggest that one of the mechanisms S. miltiorrhiza exerts its pharmacological effect is through its modulation of endothelial cell permeability.
Salvia miltiorrhoza Bunge is a traditional herb medicine often used in China for the treatment of cardiovascular disorders, such as atherosclerosis. The purpose of this study was to examine the effect of aqueous extract of Salvia miltiorrhoza Bunge (ESM) on expression of adhesion molecules in tumor necrosis factor (TNF)alpha-induced endothelial cells. When preincubated with ESM (100, 200, 400 microg/mL) for 18 hours, the adhesion of HL-60 cells to TNFalpha-induced endothelial cells was significantly decreased in a concentration-dependent manner, and down-regulation of adhesion molecules, intracellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), was also observed. The inhibitory effect of ESM on TNFalpha-induced VCAM-1 expression was attenuated by inhibition of intracellular glutathione (GSH) synthesis. In addition, ESM also significantly inhibited TNFalpha-induced translocation of nuclear factor kappaB (NF-kappaB) from cytoplasm to nuclei in endothelial cells. These results demonstrated that inhibition of ESM on the expression of adhesion molecules may result from its blocking activation on NF-kappaB. It may imply one of the mechanisms by which ESM exerts its beneficial effect preventing the progress of atherosclerosis.
A C60-pyrrolidine derivative with a hydrophobic-hydrophilic-hydrophobic structure (2-{3,4-di{2-[2-(2-decyloxyethoxy)ethoxy]ethoxy}}phenyl-3,4-fulleropyrrolidine, DTPF) has been synthesized and well-characterized. This compound could form stable nanospheres by simply injectingits tetrahydrofuran (THF) solution into water and then removing THF by purging gaseous nitrogen in sequence. Novel nanoassemblies of DTPF nanospheres and gold nanoparticles were obtained through in situ photoreduction of aqueous HAuCl4 in the presence of DTPF nanospheres, which were confirmed by UV-visible, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy methods. It is proposed that the interaction between the positively charged nitrogen atom and the gold nanoparticles is the main driving force for the formation of the nanoassemblies.
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