Keloids tend to occur on highly mobile sites with high tension. This study was designed to determine whether body surface areas exposed to large strain during normal activities correlate with areas that show high rates of keloid generation after wounding. Eight adult Japanese volunteers were enrolled to study the skin stretching/contraction rates of nine different body sites. Skin stretching/contraction was measured by marking eight points on each region and measuring the change in location of the marked points after typical movements. The distribution of 1,500 keloids on 483 Japanese patients was mapped. The parietal region and anterior lower leg were associated with the least stretching/contraction, while the suprapubic region had the highest stretching/contraction rate. With regard to keloid distribution, there were 733 on the anterior chest region (48.9%) and 403 on the scapular regions (26.9%). No keloids were reported on the scalp or anterior lower leg. Because these sites are rarely subjected to skin stretching/contraction, it appears that mechanical force is an important trigger that drives keloid generation even in patients who are genetically predisposed to keloids. Thus, mechanotransduction studies are useful for developing clinical approaches that reduce the skin tension around wounds or scars for the prevention and treatment of not only keloids but also hypertrophic scars.

Plasma membranes were isolated from the acellular slime mould Physarum polycephalum by differential centrifugation and an aqueous two-phase polymer method. ATPase activity in the membrane fraction was optimal at pH 6.5 and was severely inhibited by vanadate but resistant to oligomycin. The protein components of the plasma membrane were analysed b$ polyacrylamide gel electrophoresis. Glycoproteins were located on Western blots by incubation of the sheets with lectin-peroxidase reagents. The results indicated that most of the membrane proteins were glycosylated. Pulse-chase experiments with [3H]glucosamine showed that when the plasmodia were induced to differentiate to macrocysts, turnover of the membrane glycoproteins occurred more rapidly than in growing plasmodia. METHODS Organism and cultivation.Microplasmodia of P . polycephalum were grown in a semi-defined medium containing glucose, yeast extract, tryptone and haemin (Daniel & Baldwin, 1964). The cultures were maintained in 100 ml of the medium and agitated on a reciprocal shaker at 26°C. Macrocyst (spherule) formation was induced by transferring the plasmodia to a nutrient medium containing 0.5 M-mannitol (Chet & Rusch, 1969).Plasma membrane preparation. Plasma membranes were prepared from growing and encysting plasmodia. Microplasmodia (2 d old) were washed with saline and suspended in Tris/HCI buffer (10 mM, pH 7.5) containing 2 mM-EDTA. The suspension was cooled in an ice bath and the plasmodia were ruptured with 10 strokes in a Potter-type glass/Teflon homogenizer. The homogenate was centrifuged at 5000 g for 10 min and the pellet was suspended in the Tris buffer containing 1 mM-MgC1,. The plasma membrane fraction was sedimented by low-Abbreviations : CBB, Coomassie brilliant blue; Con A, concanavalin A ; endo H, endo-P-N-acetylglucosaminidase H; PNA, peanut agglutinin; WGA, wheat germ agglutinin. 0001-5105 0 1989 SGM 484, 386-397.

The effects of phosphoric acid in a 3-amino-propyltriethoxy silane (3-APS) coating system on electro-galvanized steel were examined in terms of the phosphoric acid effect on corrosion resistance. Acetic acid and 3-glycidoxy-propyltriethoxy silane (3-GPS) were also used for comparison of corrosion protection performance to that of phosphoric acid and 3-APS. The corrosion resistance mechanism was analyzed using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) .Adding phosphoric acid to the solution of 3-APS improved corrosion protection when the coating was immersed in 0.6 mol/dm 3 NaCl.Results show that the addition of phosphoric acid had the greatest anti-corrosion effect and that it suppressed electrolyte uptake effectively. The roles of phosphoric acid were explained by the formation of protonated amine group (-NH 3 ＋ ) and Si-O-Si bonds in the coating. These coating changes are expected to produce the superior corrosion resistance. Acetic acid had no effect on the corrosion resistance compared to phosphoric acid. Results show that 3-GPS mixed with phosphoric acid, which has no amine group in the molecule, was inferior to the 3-APS and phosphoric acid composite coating.

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Covering metal with fluorine resin can create a hydrophobic surface on metals for many applications such as self-cleaning, anti-icing, and corrosion resistance. When fluorine resin is dispersed in a coating, the material' s hydrophobicity can be controlled by altering the fluorine resin distribution in the coating. This study investigated fluorine resin dispersion effects on the hydrophobicity of an inorganic coating. The fluorine resin coverage was analyzed using X-ray photoelectron spectroscopy （XPS） and scanning low-energy electron microscopy （SLEEM） . Hydrophobicity was evaluated by the water contact angle. The contact angle on inorganic coatings in which fluorine resin was dispersed increased concomitantly with increasing amounts of fluorine resin. Furthermore, the surface coverage of the fluorine resin increased as the fluorine resin amount increased, but the coverage was not directly proportional to the resin amount. Results suggest that the fluorine resin is concentrated in the outermost layer of the coatings. The coating hydrophobicity is determined by the fluorine resin coverage on the outermost layer according to Cassie' s law. The water contact angle also depends on the drying temperature of the coatings because the fluorine resin spreads in the outermost layer when the coating is dried at a temperature higher than the resin softening point. Drying temperature (℃) Fig. 3 a） Relationship between surface F content calculated from XPS spectra of coatings dried at 140 ℃ and total content of fluorine resin in coatings b） Relationship between surface F content calculated from XPS spectra of coatings with 5% fluorine resin and drying temperature 10µm Content of fluorine resin 0% 0.3% 1% 5% Keywords