Dietary soybean protein compared with casein retards senescence in the senescence accelerated mouse

The effects of replacing dietary casein with soybean protein on mean life span, mean life span of the last one-tenth of a group, grading scores of senescence and deposition of senile amyloid were investigated in senescence accelerated mice (SAM-P/1) compared with a control strain (SAM-R/1). SAM-R/1 mice fed the soybean protein-containing diet had mean life spans of 618 +/- 42 d (males) and 578 +/- 62 d (females), 58% (males) and 44% (females) longer than those of corresponding casein fed mice (P < 0.01). Similarly, in SAM-P/1 mean life-spans were 265 +/- 16 d (males) and 307 +/- 23 d (females) in the soybean diet group, 27% (males) and 30% (females) longer than in the casein diet groups (P < 0.01). The mean life span of the last one-tenth of each group fed soybean protein was significantly longer than the corresponding group fed casein. In SAM-R/1 mice, pathological studies revealed that severe secondary amyloid deposition (amyloid A protein) in the kidneys, spleen, stomach and liver was significantly suppressed, in males only, by replacing casein with soybean protein (P < 0.01). The occurrence of contracted kidneys caused by the infiltration of amyloid A protein was suppressed in SAM-R/1 mice fed the soybean protein-containing diet (P < 0.05). The deposition of senile amyloid in SAM-P/1 mice with aging was retarded by replacing casein with soybean protein (P < 0.01). These results indicate that dietary protein source is important in modulating the advance of senescence in SAM mice.     

Conformational analysis of periodic polypeptides

Summary Theoretical conformational analysis was carried out for a periodic polypeptide composed of the repetitive Ala-Pro sequence, i.e., poly(Ala-Pro) using ECEPP and the conformational minimization procedure. Calculated results showed that a γ-helix is the most stable helical conformation of poly(Ala-Pro), and also that most of the stable helical conformations are other types γ-helices and β-helices with large value of the rise per residue. Obtained conformational preference of poly(Ala-Pro) indicates that the repetitive Ala-Pro sequence is a suitable amino-acid sequence for designing the rod-like backbone conformations of artificial proteins.     

Small, round-structured viruses (SRSVs) associated with acute gastroenteritis outbreaks in Gifu, Japan

Two outbreaks of non-bacterial gastroenteritis occurred in Gifu prefecture in January 1989 and in January 1991. Both outbreaks were closely related to the consumption of raw oysters, and showed similar clinical features. Small, round-structured virus particles were found in patient stools in both outbreaks by electron microscopy. The role of these particles as the causative agents of the outbreaks were strongly suggested by immune electron microscopy and/or western-blotting immunoassay. When compared with SRSV-9 (Tokyo/SRSV/86-510) reported previously (Hayashi et al, J. Clin. Microbiol., 27: 1728-1733, 1989), it was found that these viral particles were antigenically similar to SRSV-9, and had a major structural protein of 63 kilodaltons (kDa). Further, the prevalence of this agent in Gifu area was examined by western blot antibody assay using 67 serum samples collected from the inhabitants in 1991. The results indicated the circulation of the same or antigenically similar agent in this area.     

Conditional Fourier spectral method for direct numerical simulation of incompressible flows

A new method of treating incompressible flows with nonslip boundaries is proposed as an extension of the Fourier spectral method. This is characteristic in using the function subspace that is a hyperplane in the Fourier-transformed velocity space, prescribed by the boundary condition, as well as in taking the solenoidal field representation in the Fourier space so that the pressure term need not be involved in the main dynamics and then time-integration can simply be made by the high-order Runge-Kutta scheme. The method can be applied in a more complicated case with an active scalar. As examples, the flow transitions to turbulence in a channel and in a rectangular duct heated from below are treated.     

Single crystalline β-FeSi2 grown using high-purity FeSi2 source

We have investigated the effect of FeSi₂ source purity on the electrical property of β-FeSi₂ grown from solution. A high-purity FeSi₂ source avoided a contamination of Cu and W metals was synthesized by melting a high-purity Fe (5N) and Si (5N-up) in a quartz ampoule. Glow discharge mass spectrometry revealed that the purity of the FeSi₂ source synthesized using 5N-Fe and a quartz-ampoule-melting process is one order of magnitude higher than that of the conventional arc-melted FeSi₂ source using 4N-Fe. The β-FeSi₂ crystals grown using the high-purity FeSi₂ and Zn solvent showed n-type conduction, whereas those grown using the arc-melted FeSi₂ showed p-type. The carrier concentration of the n-type crystals was (4.9-6.3) × 10¹⁸ cm^− 3, which was more than 10 times higher than that of the p-type crystals (5.2 × 10¹⁷ cm^− 3). From the ICP-MS and SIMS analysis of the grown crystals, we found that dominant impurity concentrations (Cr, Mn, Co, Ni, Cu, Zn and W) in the p-type crystals were higher than those in the n-type ones. Therefore, the p-type conductivity of undoped crystals grown using Zn solvent results from unintentional doping by the high impurity level of the used FeSi₂ source.     

Combined effects of working environmental conditions in VDT work

The combined effects of city noise and luminance of the computer display were evaluated from the changes in lymphocytes and mental activities of participants. Healthy male students were tested under the following four experimental conditions: (1) a calculating task on a video display terminal (VDT) with luminance of 90 cd m(-2) without city noise; (2) a calculating task on a VDT with luminance of 20 cd m(-2) without city noise; (3) a calculating task on a VDT with luminance of 90 cd m(-2) with city noise of 70 dB(A); and (4) a calculating task on a VDT with luminance of 20 cd m(-2) with city noise of 70 dB(A). A visual reaction test (VRT) was performed, and critical flicker fusion frequency (CFF), heart rate (HR), numbers of circulating white blood cells (WBCs), lymphocyte subsets and subjective symptoms of fatigue were measured (1) before; (2) just after; and (3) 30 min after each 60 min test. Subjective symptoms of fatigue significantly increased just after experiments conducted under the two noisy conditions. VRT and CFF showed significant changes in the case of the high-luminance display with noise. WBCs and neutrophils showed significant increases in the two quiet conditions. These results suggested that high luminance with noise had the most effect on subjective fatigue and mental activities.