THE ESTERASE AND LIPASE ACTIVITY OF AEROBIC SKIN BACTERIA

SUMMARY.— The production of esterase and lipase by aerobic bacteria from normal human skin surfaces was tested by simple plate tests against natural and artificial substrates. Almost all of 42 strains of Micrococcaceae representative of each of Baird-Parker's subgroups produced strong esterases and lipases, as did most of the 82 strains of Sarcina spp., especially those most commonly present on healthy skin. Forty per cent of 50 aerobic skin diphtheroids and 20% of 58 aerobic nasal diphtheroids produced active lipases.     

THE IN VITRO PENETRATION OF FLUOCINONIDE THROUGH HUMAN SKIN FROM DIFFERENT VOLUMES OF DMSO

Summary.— The penetration of fluocinonide from solution in DMSO across human abdominal skin in vitro has been examined. Different volumes of solution, ranging from 0.025 ml to 0.75 ml, were studied.
The results show that better penetration is achieved in this in vitro situation from smaller volumes than from larger volumes. Possible mechanisms that might account for this phenomenon are discussed. A possible explanation considers that the flux of water into the DMSO solution causes an increase in the thermodynamic activity of the drug and hence in the penetration rate of the drug into and through the skin.     

THE MICROBIOLOGY OF THE CUTANEOUS DIPHTHEROIDS

Summary.— The cutaneous diphtheroids have very varied morphological and biochemical characters which make grouping for ecological studies difficult. Several schemes have been proposed and are discussed. For convenience, the organisms are divided into lipophilic and non-lipophilic diphtheroids, those producing porphyrins, those with some keratinolytic ability and the anaerobic diphtheroids.     

THE GROWTH OF ADULT HUMAN SKIN IN VITRO

Summary.— In this report we investigate the role of serum in organ culture of adult human skin. The migratory overgrowth of dermis by epidermal cells is shown to depend on the presence of high molecular weight (mol. wt.) components of serum. Regeneration of the epidermis after 19 days' incubation occurs in the presence of 10% whole serum in the growth medium. DNA synthesis is found to increase in long-term incubations in medium including serum components but not in the presence of Minimal Essential Medium (MEM) only.     

SURVEY OF THE DISTRIBUTION OF STEROID DEHYDROGENASES IN SEBACEOUS GLANDS OF HUMAN SKIN

SUMMARY.— This paper reports the results of a survey carried out using human skin to investigate the distribution of 3β-hydroxysteroid dehydrogenase, 16β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase over the skin surface. In common with other work, sebaceous glands were found in greater numbers in the face, scalp and thoracic region. The enzymes occur at all ages, although there was an apparent increase in activity in the 20–30 age group. The enzymes occur in both sexes, although there is a difference with the 17β-HSD, the enzyme occurring more frequently in male skin biopsies. The enzymes occur in all surface areas of the human body and differences from a previous survey are noted. In particular the enzymes are found in the scalp, the perineal region, the arms, legs and abdomen, as well as the face and chest. The difference between the localization of the 3β-HSD and 17β-HSD within sebaceous glands is described.     

EFFECTS OF MOUSE AND HUMAN EPIDERMAL GROWTH FACTOR ON THE OUTGROWING EPIDERMIS OF PIG AND HUMAN SKIN EXPLANTS

The effects of mouse and human epidermal growth factors (mEGF and hEGF) on the outgrowing epidermis of pig and human skin explants were studied. Both mEGF and hEGF significantly stimulated the rate of pig and human epidermal outgrowth at 0.01–0.05 µg/ml. mEGF also stimulated mitosis of pig outgrowing epidermis. The stimulatory effect of mEGF on the rate of pig epidermal outgrowth and mitosis of pig outgrowing epidermis was potentiated by fetal calf serum. These results indicate that EGF may have a possibile clinical application in epidermal wound healing.     

HISTOLOGY AND CYTOCHEMISTRY OF HUMAN SKIN XXXV. THE NIPPLE AND AREOLA

SUMMARY.— The undersurface of the epidermis covering the tip of the nipple resembles that found in tactile surfaces; at the sides of the nipple the undersurface is more shallow, and in the areola it has an even, honeycombed appearance. These are distinctive structural signatures of the areas. The nipple is glabrous and the areola largely so. Lactiferous ducts and sebaceous and apocrine glands open only at the tip of the nipple, mostly grouped toward the centre. Glands of Montgomery (accessory mammary glands), clusters of large sebaceous glands, a few scattered eccrine sweat glands, some apocrine glands, and a few vellus hairs toward the periphery are the appendages of the areola. Lactiferous ducts and sebaceous glands contain numbers of melanotic melanocytes among their epithelial cells. Sensory nerve end-organs are found only at the tip of the nipple; there are practically none demonstrable at the sides of the nipple or at the areola. Many nerves are loosely wrapped around the lactiferous ducts, from the lactiferous sinus to the surface. These are probably afferent nerve fibres that convey sensory impulses. Nipples and areolae have a bountiful framework of elastic fibres that give these structures rigidity and support, anchor smooth muscle fibres, keep the lactiferous ducts and sinuses from collapsing, and attach the epidermis. The nipples and areolae of women, men, girls, and boys are qualitatively identical hut quantitatively very different.     

IMMUNOCYTOLOGICAL LOCALIZATION OF LYSOZYME IN HUMAN SKIN

Antibody against human lysozyme was purified from sera of immunized rabbits using the immuno-absorption technique. After conjugation of the purified antibody against human lysozyme with fluorescein isothiocyanate (FITC), immunofluorescent studies were carried out on both normal human skin and peripheral blood cells. Specific immunofluorescence appeared in the cytoplasm of epidermal cells and was much stronger in the upper cell layer than in the basal cell layer. Only slight fluorescence appeared in the horny layer. In the dermis, linear fluorescence was found along collagen fibers. In the immunocytological examination of peripheral blood cells, lysozyme was found in the cytoplasm of the polymorphonuclear leucocytes (PMN's).     

THE EPIDERMAL-DERMAL JUNCTION OF NORMAL HUMAN SKIN AS SEEN IN FREEZE-ETCH PREPARATIONS

SUMMARY.— The epidermal–dermal junction has been examined by the replication of freeze-fractured human skin.
A basement zone about 150 nm. in depth has been observed which continuously separates epidermis from dermis. This relatively broad region has been interpreted as the hydrated form of the basement membrane.
The convoluted nature of the epidermal–dermal junction and the plasmalemmae of the basal cells is more easily followed by this method of examination, which also brings out the complexity of these appositions.
No hemidesmosomes have been observed in the contacts between the basal cells and basement membrane. Desmosomal contacts between basal cells differ in appearance from those seen in thin sections and possibly involve portions of the basement zone.     

THE DERMOSTRATION OF HYDROXYSTEROID DEHYDROGENASE ACTIVIY IN HUMAN FOETAL SKIN IN THE FIRST 32 WEEKS OF GESTATION

SUMMARY.— Specimens of skin of 25 human foetuses from 8 to 32 weeks gestation were incubated to demonstrate the presence of hydroxysteroid dehydrogenases by histochemical methods. 17β-HSD was demonstrated at 16 weeks gestation, when fully differentiated sebaceous glands were first visualized. 3β-HSD and 16β-HSD were recognized at a later stage. These enzymes were found only in sebaceous glands and in no other appendages. A comparison between the human foetal and adult pattern of enzyme activity has been drawn, and the significance of the results discussed.     

EFFECT OF THIOCYANATE ON HUMAN SKIN COLLAGENASE ACTIVITY

Using tissue culture, human skin collagenase activity and its relationship to serum collagenase inhibitors and the effect of thiocyanate was studied. The following was found:

• 1) Collagenase activity did not become apparent in the culture medium before 48 hours; it reached a peak on the 4th day, gradually decreased, and then became elevated again on the 7th day of culture.
• 2) Using the immunodiffusion technique, α₂-macroglobulin was detected up to the 4th day and α₁-antitrypsin until the 7th day.
• 3) On the 2nd day of culture, two separate peaks of collagenase activity were evident by gel filtration on a Sephadex G-200 column. One peak was eluted in the area of α₁-antitrypsin, but no collagenase activity was detected in the area of α₂-macroglobulin.
• 4) By treatment with NaSCN, the α₂-macroglobulin was dissociated from the enzyme-serum collagenase inhibitor complex, and skin collagenase was partially purified as a single peak of activity. From these results, the main serum constituent of collagenase inhibitors is considered to be α₂-macroglobulin rather than α₁-antitrypsin.