Yoichi Fujiyama

Acetaminophen-induced Hepatotoxicity in a Liver Tissue Model Consisting of Primary Hepatocytes Assembling Around an Endothelial Cell Network

Primary hepatocytes have been used in drug development for the evaluation of hepatotoxicity of candidate compounds. However, the rapid depression of their hepatic characters in vitro must be improved to predict toxicity with higher accuracy. We have hypothesized that a well organized tissue construct that includes nonparenchymal cells and appropriate scaffold material(s) could overcome this difficulty by remediating the viability and physiological function of primary hepatocytes. In this study, we constructed an in vitro liver tissue model, consisting of mouse primary hepatocytes assembling around an endothelial cell network on Engelbreth-Holm-Swarm gel, and examined its response to acetaminophen treatment. The increase in lactate dehydrogenase release after the exposure to acetaminophen was induced earlier in the liver tissue model than in monolayer hepatocytes alone, suggesting that the tissue model was more sensitive to an acetaminophen-induced toxicity. On the basis of our results, we conclude that liver tissue models of this kind may enhance the responses of hepatocytes against xenobiotics via the maintenance of hepatic genes and functions such as cytochrome P450s. These findings will contribute to the development of more accurate systems for evaluating hepatotoxicity.

Focused ion beam direct deposition of superconductive thin film

Focused ion beam direct deposition of niobium has been developed as a technique for fabricating superconductive thin films. A Nb2+ ion beam extracted from a Nb10–Au50–Cu40 liquid metal ion source was accelerated to 40 keV, focused, deflected and finally decelerated to 50–1000 eV. The beam current density was 0.4–2 mA/cm2 and the minimum deposited linewidth was about 0.5 μm. The sticking probability of the Nb2+ ion beam and the critical temperature of deposited niobium films were measured. The deposition at different deposition rates and different residual gas pressure were performed. A clear relation was obtained between the critical temperature and the concentration of contaminations. This relation is consistent with the published relation for bulk niobium if it is assumed that the sticking probability of residual gas is 0.2. However, dependence of the critical temperature on ion energy was not observed.

Integrated micro chamber for living cell analysis with negligible dead volume sample injector

We develop the micro chamber for real-time monitoring of living cell. It is integrated with an extremely low dead volume sample injector. The chamber was fabricated by the combination of isotropic etching and deep trench etching using CCP-RIE and ICP-RIE. The reproducible sample injection of the order of 1 nL is performed. Biological cell culture of HeLa is also demonstrated in a prototype device.

Evaluation of Silanol Concentration on Quartz Glass Surface for EOF Stability of CE Chip

The effects of heat treatment during fabrication process and NaOH treatment after fabrication on surface silanol (Si-OH) concentration profile are discussed. FTIR-ATR (Fourier transform Infrared Spectroscopy - Attenuated Total Reflection) method is applied to measure the surface OH concentration of materials. The result revealed that FTIR-ATR can be a simple solution for estimation of OH concentration on the glass surface.