A series of physical double-network hydrogels is synthesized based on an amphiphilic triblock copolymer. The gel, which contains strong hydrophobic domains and sacrificial dynamic bonds of hydrogen bonds, is stiff and tough, and even stiffens in concentrated saline solution. Furthermore, due to its supramolecular structure, the gel features improved self-healing and self-recovery abilities

The Hinode Solar Optical Telescope (SOT) is the first space-borne visible-light telescope that enables us to observe magnetic-field dynamics in the solar lower atmosphere with 0.2 -0.3 arcsec spatial resolution under extremely stable (seeing-free) conditions. To achieve precise measurements of the polarization with diffraction-limited images, stable pointing of the telescope (< 0.09 arcsec, 3σ ) is required for solar images exposed on the focal plane CCD detectors. SOT has an image stabilization system that uses image displacements calculated from correlation tracking of solar granules to control a piezo-driven tiptilt mirror. The system minimizes the motions of images for frequencies lower than 14 Hz while the satellite and telescope structural design damps microvibration in higher frequency ranges. It has been confirmed from the data taken on orbit that the remaining jitter is less than 0.03 arcsec (3σ ) on the Sun. This excellent performance makes a major contribution to successful precise polarimetric measurements with 0.2 -0.3 arcsec resolution.K. Kobayashi now at

Bolus-administered intracerebroventricular (ICV) relaxin-3 has been reported to increase feeding. In this study, to examine the role of relaxin-3 signaling in energy homeostasis, we studied the effects of chronically administered ICV relaxin-3 on body weight gain and locomotor activity in rats. Two groups of animals received vehicle or relaxin-3 at 600 pmol/head/day, delivered with Alzet osmotic minipumps. In animals receiving relaxin-3, food consumption and weight gain were statistically significantly higher than those in the vehicle group during the 14-day infusion. During the light phase on days 2 and 7 and the dark phase on days 3 and 8, there was no difference in locomotor activity between the two groups. Plasma concentrations of leptin and insulin in rats chronically injected with relaxin-3 were significantly higher than in the vehicle-injected controls. These results indicate that relaxin-3 up-regulates food intake, leading to an increase of body weight and that relaxin-3 antagonists might be candidate antiobesity agents.

It has been suggested that decreasing muscle pH because of the accumulation of lactic acid is a fatigue factor during high-intensity exercise [1][2][3]. Lactic acid production in muscle releases lactate (Lac Ϫ ) and hydrogen ions (H ϩ ) within the physiological pH range. Therefore the accumulation of lactic acid causes metabolic acidosis. The decrease of intracellular pH brings about muscle fatigue through several mechanisms such as decreasing skeletal muscle tension, relaxation [4], and the inhibition of phosphofructokinase activity [5]. However, the body has an ability to restrain the decrease of intracellular pH, which is known as buffering capacity. It has been suggested that a higher buffering capacity can better stabilize the intracellular pH and better enhance the capability for high-intensity exercise performance.Most intracellular buffering within the skeletal muscle is accomplished by proteins, dibasic inorganic phosphate, bicarbonate, and carnosine [6]. A large amount of the histidine-containing dipeptide carnosine (␤-alanyl-L-histidine) has been shown to be present within the skeletal muscle of most vertebrate species [7]. It has been suggested that the carnosine significantly contributes to the physicochemical Japanese Journal of Physiology, 52, 199-205, 2002 Key words: carnosine, buffering capacity, acid-base balance, fiber-type distribution, high-intensity exercise. Abstract:The histidine-containing dipeptide carnosine (␤-alanyl-L-histidine) has been shown to significantly contribute to the physicochemical buffering in skeletal muscles, which maintains acid-base balance when a large quantity of H ϩ is produced in association with lactic acid accumulation during high-intensity exercise. The purpose of the present study was to examine the relations among the skeletal muscle carnosine concentration, fiber-type distribution, and high-intensity exercise performance. The subjects were 11 healthy men. Muscle biopsy samples were taken from the vastus lateralis at rest. The carnosine concentration was determined by the use of an amino acid autoanalyzer. The fiber-type distribution was determined by the staining intensity of myosin adenosinetriphosphatase. The high-intensity exercise performance was assessed by the use of 30-s maximal cycle ergometer sprinting. A significant correlation was demonstrated between the carnosine concentration and the type IIX fiber composition (rϭ0.646, pϽ0.05). The carnosine concentration was significantly correlated with the mean power per body mass (rϭ0.785, pϽ0.01) during the 30-s sprinting. When dividing the sprinting into 6 phases (0-5, 6-10, 11-15, 16-20, 21-25, 26-30 s), significant correlations were observed between the carnosine concentration and the mean power per body mass of the final 2 phases (21-25 s: rϭ0.694, pϽ0.05; 26-30 s: rϭ0.660, pϽ0.05). These results indicated that the carnosine concentration could be an important factor in determining the high-intensity exercise performance.

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