In vivo characterization of T-794, a novel reversible inhibitor of monoamine oxidase-A, as an antidepressant with a wide safety margin

T-794 is a new reversible inhibitor of MAO type A. In order to predict its clinical utility as an antidepressant, we examined its pharmacological profile (i.e., MAO inhibitory activity, antidepressant-like activity and safety) in vivo in rodents. The p.o. administration of T-794 potentiated L-5-hydroxytryptophan-induced symptoms with ED50 = 1.01 mg/kg (mice) or 1.15 mg/kg (rats), and L-dopa-induced behavior with ED50 = 5.90 mg/kg (mice), whereas it did not alter the effect of beta-phenylethylamine even at 100 mg/kg (mice). In the L-5-hydroxytryptophan test in rats, the activity of T-794 (at twice the dose of ED50) disappeared by 8 h; the duration of action was similar to that of moclobemide. These results confirm the previous biochemical results that MAO-A inhibition by T-794 is highly selective and of short duration. T-794 was effective in three animal models of depression: reserpine reversal (mice, rats), behavioral despair test (mice) and learned helplessness (rats). In these tests, it had potency similar to or greater than moclobemide, tranylcypromine or imipramine. The p.o. administration of T-794 (30 mg/kg) did not affect the pressor effect of tyramine in anesthetized rats, whereas moclobemide (30 mg/kg) and tranylcypromine (6 mg/kg) potentiated the effect. Acute toxicity of T-794 proved to be very low (maximal tolerated dose > 2 g/kg p.o.) in contrast to brofaromine (maximal tolerated dose = 150 mg/kg p.o.). Unlike tricyclic antidepressants, T-794 did not prevent the oxotremorine-induced tremor even at 100 mg/kg p.o.; in this it demonstrated a lack of the anticholinergic activity. These results suggest that T-794 is an effective and particularly safe antidepressant and that it may make an important contribution in the treatment of depressive disorders.     

On-line recognition of hand-written characters utilizing positional and stroke vector sequences

An on-line recognition method for hand-written characters utilizing stroke vector sequences and a positional vector sequence has been developed. The number of target characters is about 2000, and fairly good recognition scores have been attained. Our scheme uses the number of strokes as the primary parameter. We employ three types of recognition strategy depending on the number of strokes. The general stroke vector sequence method, devised to analyze the shape, can represent both skeleton and local characteristics by a small amount of information; and the restricted dynamic programming method is effective to determine the shape of a stroke. The similarity of two shapes and the complexity of a stroke have been introduced to reduce the dictionary size and the processing time, respectively.     

Microwave atomic force microscopy imaging for nanometer-scale electrical property characterization

We introduce a new type of microscopy which is capable of investigating surface topography and electrical property of conductive and dielectric materials simultaneously on a nanometer scale. The microwave atomic force microscopy is a combination of the principles of the scanning probe microscope and the microwave-measurement technique. As a result, under the noncontact AFM working conditions, we successfully generated a microwave image of a 200-nm Au film coating on a glass wafer substrate with a spatial resolution of 120 nm and a measured voltage difference of 19.2 mV between the two materials.     

Electromagnetic Shielding Properties of Woodceramics Made from Wastepaper

Woodceramics are new porous carbon materials, which are made by impregnating woody materials with phenol resin and then thermoformed in a vacuum furnace and these have been shown to have electromagnetic shielding properties. In the recycling of wastepaper, ways of using the wastepaper other than for paper pulp are needed to be developed. In this study, we made Woodceramics from handbill advertisement paper and telephone directory paper, and measured their electromagnetic shielding properties in order to find new uses for wastepaper. The results showed that the Woodceramics made from wastepaper had an electric shielding effectiveness of 30 dB for 100 MHz and 40 to 43 dB for 300 MHz or higher, and had a magnetic shielding effectiveness of 30 dB for 100 MHz and 37 dB for about 400 MHz. An electric equivalent circuit of the pore model in the Woodceramics is introduced. In addition, it is proposed that the excellent electromagnetic shielding effectiveness of the Woodceramics is caused by dielectric loss.     

Preparation of an Alkali-Element-Doped CeO2-Sm2O3 System and Its Operation Properties as the Electrolyte in Planar Solid Oxide Fuel Cells

The ionic conductivity of the ceria-samaria (CeO₂-Sm₂O₃) system is higher than that of yttria-stabilized zirconia and other CeO₂-based oxides. In this study, a small amount of alkali-element-doped CeO₂-Sm₂O₃ solid solution was prepared. This solid solution was characterized by measuring the powder density and the chemical composition. Moreover, its electrochemical properties were investigated in the temperature range from 700° to 1000°C. It was found that a small amount of alkali-element-doped CeO₂ solid solution enhanced the ionic conductivity. The power density of an oxygen-hydrogen fuel cell for alkali-element-doped CeO₂-Sm₂O₃ ceramics exhibited high values at low temperatures such as 700° to 800°C. It is concluded that the improved fuel cell performance can be attributed to the high stability of this composition in the fuel atmosphere.     

Determination of surface selection rule of surface plasmon resonance near-infrared spectroscopy by using a Langmuir-Blodgett film

Near-infrared (NIR) absorption spectra of a cadmium arachidate Langmuir-Blodgett (LB) film were measured by surface plasmon resonance near-infrared spectroscopy (SPR-NIRS) based on the Kretschmann configuration with a 18.8-nm gold film. An NIR spectrum enhanced severalfold was obtained as a top ridge of the SPR-NIR spectra measured at different incident angles by using the principle of absorption-sensitive SPR. In order to determine the surface selection rule of SPR-NIRS, the enhanced NIR absorption spectrum of the LB film was compared to an unenhanced one without the gold film and to a normal incidence transmission spectrum. Moreover, a pair of out-of-plane (OP) and in-plane (IP) spectra were obtained by multiangle infrared spectroscopy analysis from a series of oblique incidence transmission measurements in the NIR region. It became obvious that the salient feature of the enhanced NIR absorption spectrum, i.e., the top ridge of the SPR-NIR spectra is almost equivalent to that of the OP spectrum. On the other hand, the unenhanced spectrum showed IP modes. These experimental results were well explained by calculation of the mean-square electric field based on the Fresnel formula.