Evaluation of drug toxicity with hepatocytes cultured in a micro-space cell culture system

A micro-space cell culture system was recently developed in which cells such as hepatocytes can be cultured and formed into a multicellular three-dimensional (3D) architecture. In this study, we assessed the performance of HepG2 cells cultured in this micro-space cell culture system in a drug toxicity test, and evaluated the effects of micro-space culture on their hepatocyte-specific functions. The micro-space cell culture facilitated the formation of 3D HepG2 cell architecture. HepG2 cells cultured in a micro-space culture plate exhibited increased albumin secretion and enhanced mRNA expression levels of cytochrome P450 (CYP) enzyme compared to those cultured in a monolayer culture. When the cells were exposed to acetaminophen, a hepatotoxic drug, the damage to the HepG2 cells grown in micro-space culture was greater than the damage to the HepG2 cells grown in monolayer culture. In addition, human primary hepatocytes grown in micro-space culture also exhibited increased albumin secretion, enhanced CYP mRNA expression levels and increased sensitivity to acetaminophen compared to those grown in monolayer culture. These results suggest that this micro-space culture method enhances the hepatocyte-specific functions of hepatocytes, including drug-metabolizing enzyme activities, making hepatocytes grown in the micro-space culture system a useful tool for evaluating drug toxicity in vitro.     

Complete detoxification of tris(1,3-dichloro-2-propyl) phosphate by mixed two bacteria, Sphingobium sp. strain TCM1 and Arthrobacter sp. strain PY1

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a flame retardant, is regarded as a potentially toxic and persistent environmental contaminant. We previously isolated a TDCPP-degrading bacterium, Sphingobium sp. strain TCM1, which, however, produced a toxic metabolite: 1,3-dichloro-2-propanol (1,3-DCP). This study was undertaken to develop a technique for complete TDCPP detoxification using strain TCM1 with a 1,3-DCP-degrading bacterium, Arthrobacter sp. strain PY1. For efficient detoxification, we designed a resting cell system and examined the effect of freezing and lyophilization treatments for preparation of their resting cells. Results show that treatments had no marked adverse effect on their activities. The TDCPP dephosphorylation by TCM1 resting cells was optimal at 30°C and pH 8.5. Also, 1,3-DCP dehalogenation by strain PY1 resting cells was optimal at 35°C and pH 9.5. Under those respective conditions, the activities were 2.48 μmol h^− 1·OD₆₆₀^− 1 for TDCPP and 0.95 μmol h^− 1·OD₆₆₀^− 1 for 1,3-DCP. Based on these results, we set the reaction temperature to 30°C and pH to 9.0. Then we examined the detoxification of 50 μM TDCPP using mixed resting cells at a final OD₆₆₀ of 0.05 for strain TCM1 and 0.2 for strain PY1. In these conditions, TDCPP was eliminated after 1 h, but some of the resulting 1,3-DCP remained at a constant level. The increase in strain PY1 cells to a final OD₆₆₀ of 4.0 decreased the TDCPP dephosphorylation rate of strain TCM1 cells but achieved complete detoxification of TDCPP during 12 h of reaction.     

Visual expression analysis of the responses of the alternative oxidase gene (aox1) to heat shock, oxidative, and osmotic stresses in conidia of citric acid-producing Aspergillus niger

The citric acid-producing filamentous fungus Aspergillus niger WU-2223L shows cyanide-insensitive respiration catalyzed by alternative oxidase in addition to the cytochrome pathway. Sequence analysis of the 5' flanking region of the alternative oxidase gene (aox1) revealed a potential heat shock element (HSE) and a stress response element (STRE). We have previously confirmed aox1 expression in conidia. In this study, to confirm whether the upstream region of aox1 responds to various stresses, we used a visual expression analysis system for single-cell conidia of the A. niger strain AOXEGFP-1. This strain harbored a fusion gene comprising aox1 and egfp, which encodes the enhanced green fluorescent protein (EGFP). The fluorescence intensity of EGFP increased in conidia of A. niger AOXEGFP-1 that were subjected to heat shock at 35-45 °C, oxidative stress by exposure to 5mM paraquat or 1 mM t-butylhydroperoxide, or osmotic stresses by exposure to 0.5 M KCl or 1.0 M mannitol. These results indicate that the putative HSE and STRE in the upstream region of aox1 directly or indirectly respond to heat shock, oxidative, and osmotic stresses.     

Anti-obesity and anti-diabetic effects of ethanol extract of Artemisia princeps in C57BL/6 mice fed a high-fat diet

Artemisia princeps is commonly used as a food ingredient and in traditional Asian medicine. In this study, we examined the effects of long-term administration of an ethanol extract of A. princeps (APE) on body weight, white adipose tissue, blood glucose, insulin, plasma and hepatic lipids, and adipocytokines in C57BL/6 mice fed a high-fat diet. Daily feeding of a 1% APE diet for 14 weeks normalized elevated body weight, white adipose tissue, and plasma glucose and insulin levels, and delayed impaired glucose tolerance in mice a fed high-fat diet. These events were not observed in mice fed a control diet containing 1% APE. Liver triglyceride and cholesterol levels were similar in mice fed a 1% APE-diet and those fed a control diet. In the high-fat diet groups, APE inhibited hepatic fatty acid synthase (FAS) and suppressed the elevation of plasma leptin, but had no effect on adiponectin levels. These findings suggest that the regulation of leptin secretion by APE may inhibit FAS activity with subsequent suppression of triglyceride accumulation in the liver and adipose tissues. Inhibition of lipid accumulation can, in turn, lead to improvements in impaired glucose tolerance.     

Group feature extraction based on matrix factorization from long-range office-logging data

To increase the productivity of knowledge workers, it is necessary to manage their organization so that they are motivated to collaborate with each other for their synergy. However, it is difficult for managers to grasp the explicit interactions of workers in the organization all the time. Owing to advanced communications technology, and the reduced size and improved capabilities of computers, we are able to record group behaviors as logging data in the office. The aim of this study is to extract features of group behavior from long-range office-logging data. We apply principal component analysis to the data matrix whose element is the mean travel velocity calculated from an individual’s trajectory per day. The results demonstrate the feasibility of our approach, since nontrivial informative group features can be extracted.     

Chemical heat-pump system working at exhaust temperatures of high-temperature-gas-cooled reactor

A chemical heat-pump system using two hydrogen-absorbing alloys is proposed to utilize heat exhausted from a high-temperature source such as high-temperature-gas-cooled reactor, HTGR, which is designed to produce H₂ more efficiently. The overall system proposed here consists of HTGR, He gas turbines, chemical heat pumps and reaction vessels corresponding to the three-step decomposition reactions comprising the I–S process. A fundamental research is performed experimentally on heat generation in a single bed packed with a hydrogen-absorbing alloy that works at the H₂ production temperature. The hydrogen-absorbing alloy of Zr(V_1−xFe_x)₂ is selected as a material that has a proper plateau pressure for the heat-pump system operated between the input and output temperatures of HTGR. Temperature jump due to heat generated when the alloy absorbs H₂ proves that the alloy–H₂ system can heat up the exhaust gas even at 600 °C without any external mechanical force.     

Preparation of Cu2ZnSnS4 thin films by sulfurizing electroplated precursors

Cu₂ZnSnS₄ (CZTS) thin films were prepared by sulfurizing precursors deposited by electroplating. The precursors (Cu/Sn/Zn stacked layers) were deposited by electroplating sequentially onto Mo-coated glass substrates. Aqueous solutions containing copper sulfate for Cu plating, tin sulfate for Sn plating and zinc sulfate for Zn plating were used as the electrolytes. The precursors were sulfurized by annealing with sulfur at temperatures of 300, 400, 500 and 600 °C in an N₂ gas atmosphere. The X-ray diffraction peaks attributable to CZTS were detected in thin films sulfurized at temperatures above 400 °C. A photovoltaic cell using a CZTS thin film produced by sulfurizing an electroplated Sn-rich precursor at 600 °C exhibited an open-circuit voltage of 262 mV, a short-circuit current of 9.85 mA/cm² and an efficiency of 0.98%.     

Antioxidant property of polyhydroxylated naphthoquinone pigments from shells of purple sea urchin Anthocidaris crassispina

Sea urchin gonads are highly priced sushi foodstuff “Uni” in Japanese traditional food, but after removal of them the residual shells with spines are dumped as waste. However, sea urchin shells contain naphthoquinone pigments with several phenolic hydroxyl groups, which were expected to act as potent antioxidant substances by donating hydrogens. Our previous study has evaluated their antioxidant ability to depress lipid peroxidation. This study examined other antioxidant property of the pigments from purple sea urchin shells, which possess larger amount of pigments than those of red and green sea urchins. The pigments as well as known antioxidant, α-tocopherol, exhibited 1,1-diphenyl 2-picryhydrazyl (DPPH) radical scavenging ability. Superoxide anion radical and hydrogen peroxide were also scavenged while hydroxyl radical, one of the most reactive oxygen species, was not significantly inhibited. However, because the pigments had significant activity to scavenge hydrogen peroxide and superoxide anion radical that could be in vivo precursors of hydroxyl radical, sea urchin pigments would be able to depress the generation of its related active oxygen radical species. These results suggested that sea urchin shells, which are still regarded as food waste, would be a new bio-resource for obtaining natural antioxidant.     

Space charge field effect on light emitting from tetracene field-effect transistor under AC electric field

By applying square wave AC voltage to the Au source electrode of tetracene based field-effect transistor (FET), electroluminescence (EL) was obtained. The results suggest that electrons and holes were injected alternately from the source electrode and recombined each other, and lead to the EL. This type of EL was localized at the interface between the source electrode and tetracene, and enhanced periodically with two relaxation times in accordance with the applied AC voltage cycle. We modeled the carrier behavior in the FET and explained the decay of EL, taking into account the space charge field contribution. Finally, using an AC voltage superposed on DC bias voltage, it was shown that electron injection was prompted only by space charge field.