Color reaction of some sapogenins and saponins with vanillin and sulfuric acid

Effect of Coenzyme Q10 (CoQ10), an essential coenzyme in oxidative phosphorylation in the mitochondria, was studied in the rat's pancreas. A dose of pancreozymin (0.2 u/100 g body wt) was injected into the femoral vein at 20 min intervals. The initial injection produced a definite increase in amylase output and the pancreatic juice flow. Subsequent injections, however, caused smaller responses than the preceding (tachyphylaxis). When CoQ10 (3 mg/100 g body wt) had been administrated 1 hour prior to the initial stimulation, both the amylase output and the rate of juice flow were significantly enhanced: the tachyphylaxis almost disappeared. Effect of CoQ10 was also observed in the isolated and perfused pancreas. CoQ10 produced slight increase in pancreozymin-induced amylase output, but the increase was not significant. The effect of CoQ10, to increase the pancreatic blood flow, seems to be involved in the in situ effect of CoQ10 in cooperation with the direct effect on pancreatic acinar cells.     

Mechanochemistry and permeability of polyelectrolyte complex membranes composed of poly(vinyl alcohol) derivatives

Two polyanions and two polycations were prepared by the esterification of poly(vinyl alcohol). Properties of their neutral polyelectrolyte complex membranes were compared with those of polyelectrolyte membranes. The charged state on the membranes was related closely to the mechanochemical reaction, the salt rejection, and the solution permeability. Both the salt rejection and the water flux of neutral polyelectrolyte complex memberanes were lower than those of the corresponding acidic or basic complex membranes.     

Glutamate receptors: brain function and signal transduction

Glutamate receptors are important in neural plasticity, neural development and neurodegeneration. N-methyl-d-aspartate (NMDA) receptors and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors act as glutamate-gated cation channels, whereas metabotropic receptors (mGluRs) modulate the production of second messengers via G proteins. Molecular studies from our and other laboratories indicated that NMDA receptors and mGluRs exist as multiple subunits (NMDAR1 and NMDAR2A-2D) and multiple subtypes (mGluR1-mGluR8). In light of the molecular diversity of glutamate receptors, we explored the function and intracellular signaling mechanisms of different members of glutamate receptors. In the visual system, retinal bipolar cells receive glutamate transmission from photoreceptors and contribute to segregating visual signals into ON and OFF pathways. The molecularly cloned mGluR6 is restrictedly expressed at the postsynaptic site of ON-bipolar cells in both rod and cone systems. Gene targeting of mGluR6 results in a loss of ON responses without changing OFF responses and severely impairs detecting visual contrasts. Since AMPA receptors mediate OFF responses in OFF-bipolar cells, two distinct types of glutamate receptors effectively operate for ON and OFF responses. mGluR1 and mGluR5 are both coupled to inositol triphosphate (IP3)/calcium signal transduction with an identical agonist selectivity. Single-cell intracellular calcium ([Ca2+]i) recordings indicated that glutamate evokes a non-oscillatory and oscillatory [Ca2+]i response in mGluR1-expressing and mGluR5-expressing cells, respectively. This difference results from a single amino acid substitution, aspartate of mGluR1 or threonine of mGluR5, at the G protein-interacting carboxy-terminal domains. Protein kinase C phosphorylation of the threonine of mGluR5 is responsible for inducing [Ca2+]i oscillations in mGluR5-expressing cells and cultured glial cells. Thus, the two closely related mGluR subtypes mediate diverging intracellular signaling in glutamate transmission.     

Acetylene–butadiene copolymer for polymer coatings

Low molecular weight, M?_n 1800–2400, and soluble copolymers of acetylene and butadiene were prepared by nickel naphthenate–diethylaluminum chloride catalyst. These copolymers possess high cure tendency to give insoluble and highly crosslinked films. The curing ability can be controlled by the amount of acetylene content in the copolymer and is in the following order: acetylene–butadiene copolymer > tung oil > cis-1,4-polybutadiene ? linseed oil, 1,2-polybutadiene, butadiene–isobutylene copolymer. Chemical modifications of the copolymer such as maleic reaction, metallation by lithium or sodium, graft polymerization by methyl methacrylate, 4-vinylpyridine or vinyl acetate, and epoxidation were also examined. The divinyl methylene in the copolymer gives a high cure tendency and high chemical reactivity.     

3-D analysis of functional instabilities of the ankle using digital still cameras

A technique to analyze the functional instability of an ankle is proposed. The technique is based on measurements using two digital still cameras. We carried out several experiments using this technique. Subjects are requested to stand on an experimental table whose angle of inclination is adjusted. By comparing the postures of both feet, we could tell that the subjects had experienced an ankle sprain and had functional instabilities in their ankles.This work was presented in part at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

Anomalous Hall effect governed by electron doping in a room-temperature transparent ferromagnetic semiconductor

Ferromagnetic semiconductors are believed to be suitable for future spintronics, because both charge and spin degrees of freedom can be manipulated by external stimuli. One of the most important characteristics of ferromagnetic semiconductors is the anomalous Hall effect. This is because the ferromagnetically spin-polarized carrier can be probed and controlled electrically, leading to direct application for electronics. Control of the Curie temperature and magnetization direction by electronic field, and photo-induced ferromagnetism have been performed successfully using the anomalous Hall effect for group III-V ferromagnetic semiconductors. In these cases, the operation temperature was much below room temperature because of the limited Curie temperature of less than 160 K (ref. 6). Here, we report on the anomalous Hall effect governed by electron doping in a room-temperature transparent ferromagnetic semiconductor, rutile Ti(1-x)Co(x)O(2-delta) (of oxygen deficiency delta). This result manifests the intrinsic nature of ferromagnetism in this compound, and represents the possible realization of transparent semiconductor spintronics devices operable at room temperature.     

Low-temperature direct synthesis of CeO2-ZrO2 solid solution nanoparticles by a hydrothermal method

Well-crystallized CeO2-ZrO2 solid solution nanoparticles were successfully prepared by a hydrothermal method in a single step at 120 degrees C, for 6 h without any post heat treatment. The particle sizes of 6 +/- 3 nm by surface area measurements are in good agreement with crystallite sizes of 6 +/- 3 nm by X-ray diffraction. Transmission microscopy also confirmed the formation of crystals of 5-8 nm in the products. In the formation of the homogeneous solid solutions the complete oxidation of Ce3+ to Ce4+ in the precipitated gels seems to be one of the important steps. The solid solutions contained several wt % water, but it was expelled by calcining > or = 600 degrees C. The heating of the samples brought about grain growths, but did not change the phases. The specific areas of 120-200 m2/g of as-prepared samples were decreased to 4-14 m2/g by heating at 900 degrees C for 4 h.