Effects of Baccharin Isolated from Brazilian Green Propolis on Adipocyte Differentiation and Hyperglycemia in ob/ob Diabetic Mice

Propolis is a honeybee product with various biological activities, including antidiabetic effects. We previously reported that artepillin C, a prenylated cinnamic acid derivative isolated from Brazilian green propolis, acts as a peroxisome proliferator-activated receptor γ (PPARγ) ligand and promotes adipocyte differentiation. In this study, we examined the effect of baccharin, another major component of Brazilian green propolis, on adipocyte differentiation. The treatment of mouse 3T3-L1 preadipocytes with baccharin resulted in increased lipid accumulation, cellular triglyceride levels, glycerol-3-phosphate dehydrogenase activity, and glucose uptake. The mRNA expression levels of PPARγ and its target genes were also increased by baccharin treatment. Furthermore, baccharin enhanced PPARγ-dependent luciferase activity, suggesting that baccharin promotes adipocyte differentiation via PPARγ activation. In diabetic ob/ob mice, intraperitoneal administration of 50 mg/kg baccharin significantly improved blood glucose levels. Our results suggest that baccharin has a hypoglycemic effect on glucose metabolic disorders, such as type 2 diabetes mellitus.     

Effect of Whole Tissue Culture and Basic Fibroblast Growth Factor on Maintenance of Tie2 Molecule Expression in Human Nucleus Pulposus Cells

Previous work showed a link between Tie2⁺ nucleus pulposus progenitor cells (NPPC) and disc degeneration. However, NPPC remain difficult to maintain in culture. Here, we report whole tissue culture (WTC) combined with fibroblast growth factor 2 (FGF2) and chimeric FGF (cFGF) supplementation to support and enhance NPPC and Tie2 expression. We also examined the role of PI3K/Akt and MEK/ERK pathways in FGF2 and cFGF-induced Tie2 expression. Young herniating nucleus pulposus tissue was used. We compared WTC and standard primary cell culture, with or without 10 ng/mL FGF2. PI3K/Akt and MEK/ERK signaling pathways were examined through western blotting. Using WTC and primary cell culture, Tie2 positivity rates were 7.0 ± 2.6% and 1.9 ± 0.3% (p = 0.004), respectively. Addition of FGF2 in WTC increased Tie2 positivity rates to 14.2 ± 5.4% (p = 0.01). FGF2-stimulated expression of Tie2 was reduced 3-fold with the addition of the MEK inhibitor PD98059 (p = 0.01). However, the addition of 1 μM Akt inhibitor, 124015-1MGCN, only reduced small Tie2 expression (p = 0.42). cFGF similarly increased the Tie2 expression, but did not result in significant phosphorylation in both the MEK/ERK and PI3K/Akt pathways. WTC with FGF2 addition significantly increased Tie2 maintenance of human NPPC. Moreover, FGF2 supports Tie2 expression via MEK/ERK and PI3K/Akt signals. These findings offer promising tools and insights for the development of NPPC-based therapeutics.     

High-Temperature Passive Oxidation of Chemically Vapor Deposited Silicon Carbide

The oxidation behavior of chemically vapor deposited (CVD) SiC at high temperature was investigated using a thermogravimetric technique in the temperatures range of 1823 to 1948 K. The specimens were prepared by chemical vapor deposition using SiCl₄, C₃H₈, and H₂ as source gases. The oxidation behavior of the CVD-SiC indicated "passive" oxidation and a two-step parabolic oxidation kinetics over the entire temperature range. The crystallization of the SiO₂ film formed may have caused this two-step parabolic behavior. The parabolic oxidation rate constant ( K _p) varied with the square root of the oxygen partial pressure ( P ^1/2_O2). The activation energy for the oxidation was determined to be 345 and 387 kJ · mol⁻¹. These values suggest that the diffusion process of the oxygen ion which passes through the SiO₂ film is rate-controlling.     

Quality Assessment of Heated Cooking Oil,Agab, Using a Simple Newly-Developed Spectrophotometric Method

Deep fat frying is one of the most widely used cooking practices but heat treatment produces many degradation products, some of which may cause health hazards. A simple, rapid, and inexpensive method for assessment of the quality of cooking oil used for frying was developed using a spectrophotometer. Potato slices were heated in Agab oil (soybean/sunflower:1/l volume) at 180 ± 5 °C for 8 h per day for 6 consecutive days. Heated samples were collected at 15-min intervals and UV absorbance at λ = 370–400 nm was measured; samples were also analyzed for anisidine value (AV), conjugated diene formation (CD), and total polar compounds (TPC). A systematic increase of absorbance in heated oil over frying time was observed. TPC was highest (R ² = 0.99) for the correlation with heating time followed by CD (0.93) and AV (0.89). The spectrophotometric method developed in the present study to assess the quality of heated oils is simple, quick, and reliable because its results were strongly correlated with the results from the TPC.     

Study of 1000-kV network protection

Electric power systems in Japan are developing due to economic growth. Especially, recent demand for electrical power in metropolitan areas has increased by more than 250 percent since 1973 when the 50-kV system was first used. Increasing power demands will continue in the future. To satisfy this demand, utilities developed new transmission lines to make networks substantial with stable and efficient operation of the power system. However, this countermeasure causes extremely large fault currents at the substations where large power sources are concentrated. Problems such as large fault currents beyond interrupting the capacity of a circuit breaker or electromagnetic interference have become more severe. To solve these difficulties, Tokyo Electric Power Company is going to develop 1000-kV networks. These increase the capacity of transmitted power and suppress the fault current level by splitting the 500-kV system into several parts. Considering the associated difficulties of 1000-kV networks (such as increasing capacitive current on transmission line), prolonged dc time constants due to large diameter conductors and other electrical characteristics of 1000-kV networks, we examine the applications of a reliable protection system. The results are summarized as follows:

• 1 1) To adopt multiple phase autoreclosing with highspeed grounding switches to suppress secondary arcing on faulted phases.
• 2 2) To adopt air-core type CT for 1000-kV busbar protection as a countermeasure against CT saturation.
• 3 3) To adopt the current comparison scheme to realize sensitive protection for paralleled transformer bank.

A new protection system will be field-tested in 1995.     

InA1As/InGaAs low-band-gap cell on InP for high efficiency multi-structure solar cell system

InA1As/InGaAs solar cells on InP for a low-band-gap cell have been fabricated. From theoretical simulation it is expected that the optimized InA1As/InGaAs cell should have photovoltaic characteristics values of J_sc = 21.2 mA cm⁻², V_oc = 0.345 V, FF = 0.745 and ν = 4.02% at one sun AM0 without an AR-coating. The best performance achieved by experiment was J_sc = 22.0 mA cm⁻², V_oc = 0.320 V, FF = 0.695, ν = 3.61% without an AR-coating. The uniformity of the characteristics was much improved utilizing the InGaAs cap layer for a low contact resistivity.     

Alternating copolymers from the radical copolymerization of citraconic derivatives with isobutyl vinyl ether

Radical copolymerization of citraconic anhydride (CAn) with isobutyl vinyl ether (IBVE) was studied as well as the copolymerizations of N-alkylcitraconimides, dialkyl citraconates and mesaconates with IBVE. All the copolymerizations attempted except one, incorporating N-alkylcitraconimide, were found to give alternating copolymers with molecular weights of more than 10,000 in most cases. Of all the copolymerizations, the CAn-IBVE system showed the highest reactivity. A charge transfer complex between these two monomers was confirmed to exist in this system. The equilibrium constant of the complex formation was determined by UV spectroscopy as 0–162 litre/mol in CHCl₃ at 15°C. The alternating copolymer obtained from CAn with IBVE was converted to the corresponding copolymer of dialkyl citraconate by esterification.     

Aluminum Nitride Fibers Synthesized from Alumina Fibers Using Gas-Reduction–Nitridation Method

Aluminum nitride fibers were successfully synthesized from alumina fibers using an NH₃–C₃H₈gas mixture as a reduction–nitridation agent. Observation using SEM clearly demonstrated that the morphology of the nitrided fibers was exactly the same as that of the raw alumina fibers, retaining the original regular shape and smooth surface. Up to 95% of the starting alumina was converted to aluminum nitride at 1400°C within 0.5 h via a single-step synthesis process.