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

236 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS by hypophyseal growth hormone gonadectomy did not alter rate of hair growth in hypophysectomised rats. Cortisone given orally in large doses temporarily restored hair growth in human alopecia, and intradermal injection of hydrocortisone acetate produced local growth of hair in a case of universal alopecia due to financial stress. 4ø The uptake of cobalt and nickel by various organs of mice was reported 4• to be correlated with hair colour, more cobalt being absorbed by black mice, more nickel by white mice. SWEAT The appearance of a new and greatly expanded edition of Kuno's Human Perspiration •2 provides an up-to-date compendium on the mechanism of sweating. A review • with 221 references on the pharmacology of sweating appeared in 1955. A study • of the pH of sweat produced by various forms of stimulation disclosed that any changes in pH obtained on the skin in response to a stimulus was in the direction oi an increase. The pH changes observed were attributed primarily to eccrine, not apocrine sweat. Fatigue of the sweat glands was produced by repeated intradermal injections of mecholyl sweat production gradually declined until the glands became refractory to further stimulation either by mecholyl or by heat. 4• The histology of apocrine sweat glands •5 and their innerration • was more adequately reported than before, and hormones of wide variety were tested •7 topically and systemically, and found to be without observable effect, although hormonal control is strongly indicated by the fact that apocrine glands start functioning at puberty. Examination of the wax- producing glands of the human ear canal led to the conclusion that they should be classed as apocrine glands. •8 Shelly's earlier conclusions as to the mechanism of axillary odour produc- tion 5ø were supported by new studies • which showed that apocrine sweat and sebum both remained free of unpleasant odour while sterile bacteria of various species were collected from human axill•e, and pure cultures of all but one of the species collected were found to produce bad odours in apocrine sweat it was concluded that the benefit of aluminium salts should not be attributed to suppression of eccrine sweating,, since they are also antibacterial, and may decrease the bacterial population of the axill•e. SEBUM Thiamine deficiency produced marked atrophy and loss of lipid in sebace- ous glands of mice. '2 Mitochrondria in the cells of the sebaceous glands appeared to play a directire part in the synthesis of sebaceous lipids, but not to undergo direct transformation into lipids. • The rate of sebaceous secretion in the forehead in ten elderly persons averaged 31 micrograms per