234 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS to' evaluate various cosmetic ingredients in • terms of their ability to increase or maintain water content, and has led to the use of the Shore Durometer for assessing skin softness. 7 Another study 8 indicated that: (1) oil-in- water emulsions are more effective in hydrating keratin than water-in-oil (2) high-viscosity emulsions are superior to those of low viscosity (3) water- miscible adjuvants increased water loss, even if they increased viscosity (4) hygroscopic substances did not increase water absorption by dried keratin. Administration of cortisone or ACTH increased the resistance of skin capillaries in humans or in rabbits while that of testosterone to females or of progesterone to males decreased the resistance. The capillary resistance in females was increased by estrone in small doses and by progesterone it was decreased by large doses of estrone. • Polarigraphic measurement of oxygen in human skin •ø disclosed wide changes in oxygen tension with variations in circulation and metabolism. The rate of carbon dioxide elimination from human skin was reported • to be increased by 15 to 20 per ,cent within an hour after drinking tea, indicating increase in skin metabolism under control of the cerebral cortex. Methionine was added • to the list of amino-acids previously found on the skin. Extraction of human epidermis with 6M urea failed to yield a TM protein similar to the "epidermin" similarly extracted •4 from cow snout epidermis. A hydrogen-bond breaker, 75 per cent lithium bromide solution, did, however, extract from human epidermis a fibrous protein different from any previously obtained and postulated to be a keratin precursor. Rats fed a diet containing only C-8, C-10, and C-12 fatty acid glycerides had fat from skin and subcutaneous tissue with higher saponification number and lower iodine number than similar fat from controls, indicating that the medium-weight fats can be deposited in the skin. •' Incubation of skin with acetate-l-C TM gave results leading to the hypothesis" that the main site of sterol synthesis is the keratinising epidermis, while the main site of squalene synthesis is the sebaceous gland. Electron-microscopic studies •8 have greatly expanded our knowledge of cellular components in the epidermal layers, and have confirmed the existence of tonofibrils crossing cell boundaries. The observations suggest that the tonofilaments are synthesised in the basal layer and transformed in the stratum granulosum into a non-filamentous but densely packed material which is presumably keratin. At this Society's 1956 Seminar, a symposium on keratinisation included reviews TM of the biochemical, physiological, and pathological aspects of keratinisation. New observations have demonstrated the presence and/or the •1ocation of the enzymes cholinesterase•, •, monoamine oxidase •, guanine deaminase" (in rat skin but not in human skin), and phosphomonoesterase. •

SOME NEW KEYS TO COSMETIC CHEMISTRY--1956 235 Ultraviolet light and, in the presence of photosensitisers, daylight, inhibit the activity of H-transferring enzymes in the skin by oxidising their SH groups. 26 Human skin in vitro synthesised phospholipid from inorganic labelled P320 41salts." Effects of various substances on the skin or its components were studied. Sodium dodecyl sulphate combined •8 with alpha-keratose of molecular weight 48,000 in two ways: (1) in firm combination, with the positive groups on the protein (2) in larger amounts held by looser forces. Alkaline shaving soaps kept the skin surface alkaline for as much as four hours after use, •9 but use of a slightly acid after-shaving lotion counteracted the effect. The nerve fibres of the peripheral nervous system of the skin of humans and cats were specifically affected by applications of acetone. TM Neutral ointments containing 0.1M concentration of salts of A1, Ca, Cr, Fe, Mn, Ni, or Zn, rubbed on 'dehaired guinea pig flanks daily for ten days, caused slight thickening of the epidermis. 3• A similar application of copper salts thickened the epidermis threefold. At non-toxic concentrations (0.01M or 0-001M) • copper doubled the epidermal thickness. The phagocytic activity of endo- thelial cells was increased 3•' by topical application of coal tar, Ti tannate, and Ti salicylate, and to a lesser extent by many other substances the effects were greater from an ointment containing the drug in an ethanolamine base, than from one with a petrolatum base. Soaking of the skin in solutions of soap or detergent reduced its water-holding capacity slightly more than did ' soaking in water TM detergents did not seem to differ significantly from soaps in this respect. A method for assay of succinic dehydrogenase and cytrochrome oxidase activities in epidermis homogenates was developed, 34 with the hope that changes in enzyme activity might be correlated with functional and structural abnormalities. HAIR Until recently it was believed that adult epidermis could not create new hair follicles. In 1954, however, new hair follicles and sebaceous glands were shown to be produced in scar tissue of rabbits, 35 and last year the formation of hair follicles from the reconstituted epidermis in abraded areas of the facial skin was observed in five adult humans. 36 Restricted food intake inhibited hair growth in mice, to degrees dependent on phase of growth in which diet was reduced. 37 The fat content of the skin was found to vary little during the hair growth cycle in mice, although the adipose layer is at least twice as thick during late phases of the cycle, due largely to the bulbs of the hair follicles, which grow into the adipose only in late phases. a8 Regrowth of hair on shaved skin of rats was greatly accelerated by removal of the pituitary or the adrenals, TM and this growth was inhibited by injection of hypophyseal adrenocorticotropin, or by chorionic gonadotropins, but not