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.     

THE EFFECTS OF SOME COMPOUNDS ON THE ENDOGENOUS RESPIRATION OF SKIN

SUMMARY.— The effects of 2-bromostearic acid, 2: 4-dinitrophenol and menadione on the respiration of skin slices in the presence or absence of added glucose was measured. All 3 compounds depress endogeneous respiration, whereas in the presence of added substrate, 2-bromostearic acid has no effect and 2: 4-dinitrophenol and menadione stimulate respiration. Since cells in the upper part of the epidermis are in a giucose-free environment, it is suggested that in vitro tests of potentially toxic substances should be performed both in the presence and in the absence of glucose.     

OBSERVATIONS ON THE SURFACE FLORA OF THE SKIN AND ON THE SKIN pH

SUMMARY. —The skin surface flora of 204 individuals was investigated quantitatively at 6 sites, using the Sellotape stripping method. In 51 of these individuals the skin pH was also measured.
There were significant differences between individuals in the number of bacteria recovered but not between sites.
Significantly greater numbers of bacteria were recovered from females than from males.
The skin pH readings showed small but significant differences between individuals and between sites, but no correlation could be demonstrated between pH and bacterial count.     

FLUORIMETRIC ASSAY OF CARBOXYLIC ESTER HYDROLASES IN GUINEA-PIG SKIN AND THE EFFECTS OF PROPRANOLOL

Summary.— The application of a continuous fluorimetric assay technique to carboxylic ester hydrolases (including the cholinesterases) in skin is described.
The kinetic properties of guinea-pig skin preparations from different anatomical sites are reported.
The in vitro and in vivo effects of propranolol and some other pharmacological compounds on carboxylic ester hydrolases from guinea-pig skin are described.
The results are discussed in relation to atopy.     

EFFECTS OF BETAMETHASONE 17 VALERATE ON THE CYCLIC AMP SYSTEM OF THE PIG SKIN EPIDERMIS

It has been reported that hydrocortisone had a protective effect on beta-adrenergic adenylate cyclase system of the pig epidermis during in vitro long term incubation. Using the same experimental system, the effects of another glucocorticoid, betamethasone 17 valerate were investigated. In short term experiments (5 min incubation time), betamethasone had no effect on the cyclic AMP accumulation of the epidermis. When skin slices were incubated with this compound for 48 hours, the response of the skin to epinephrine was preserved and showed a greater accumulation of cyclic AMP in betamethasone-treated skin than in the control. This effect was observed at concentrations greater than 0.001 μM of betamethasone, with the maximal accumulation of cyclic AMP at 0.1 μM. Neither histamine responsiveness nor cyclic AMP phosphodiesterase activities (low and high Km enzymes) were altered by the betamethasone treatment. Thus, betamethasone showed a protective effect against the beta-adrenergic adenylate cyclase system similar to that of hydrocortisone in much lower concentrations. These effects of glucocorticoids would be the essential pharmacological action of this type of hormone on epidermis, and glucocorticoids might reveal their biological activity through the cyclic AMP system of the skin.     

THE SKIN AND FRICTION: DEVIATIONS FROM AMONTON''S LAWS, AND THE EFFECTS OF HYDRATION AND LUBRICATION

SUMMARY.— The coefficient of friction has been determined for skin and various materials. It has been established that the behaviour of skin is not portrayed by the simple laws of friction, but by a more complex relationship of the type F =_μWⁿ. This is probably because skin is subject to viscoelastic rather than purely plastic deformation. Friction may be altered by the type of material in contact with skin and is further influenced by surface lubrication. Dry talcum powder reduces friction slightly for certain materials against skin, but increases friction when it becomes wetted.     

MORPHOLOGICAL AND BIOCHEMICAL STUDIES ON THE DEVELOPMENT OF FOETAL MOUSE SKIN

SUMMARY.— It has been noted that biochemical and morphological changes occurred simultaneously during the embryogenesis of mouse skin. The onset of histological maturation of collagen fibres coincided with a change in the pattern of the in vitro incorporation of both ³⁵SO₄ into the sulphated mucopoly-saccharide and ¹⁴C-proline into the collagen of whole skin. Simultaneously, an increase in thickness and differentiation of the epidermis and changes in the basement membrane were observed. Thus, by applying a variety of techniques it has been demonstrated that a critical period of skin maturation involving dermis and epidermis is reached on the eighteenth day of embryogenesis in the mouse.     

银屑病皮损和非皮损处直接免疫荧光的研究

本文用直接免疫荧光法测定了30例进行期寻常型银屑病患者皮损和非皮损处Ig及C_3沉积率。结果表明,患者皮损角质层IgG、IgA、IgM及C_3沉积率分别为83.3%、66.7%、60.3%、和80.0%,非皮损处分别为30.0%、16.0%、16.0%和26.7%,两者间有高度显著性差异(P<0.001)。有些病例在Munro氏微脓肿毛细血管壁周围及皮肤附属器可见到点团状荧光。结果提示结合于角质层的Ig及C_3与银屑病的发病有一定关系。     

MECHANISM OF ACTION OF ACCELERANTS ON SKIN PENETRATION

SUMMARY.— The ability of a number of liquids to increase the permeability of human skin in vitro has been assessed in terms of their power to accelerate the percutaneous penetration of tri- n -propyl phosphate (TPP).
The most effective "accelerants". 8 M-urea and dimethylsulphoxide (DMSO), increased the permeability of full thickness skin to TPP up to 190 times, they were also amongst those compounds, which produced the greatest reduction in skin impedance and the most swelling of the stratum corneum, suggesting that part of their effectiveness may be due to an ability to lower the diffusional resistance of the stratum corneum.
The acceleratns were all able to extract soluble components from the stratum corneum; DMSO extracted lipoprotein, and chloroform-methanol extracted phospholipids, suggesting the possibility of ultrastructural modifications consistent with an increase in permeability.
For a liquid to be a good accelerant it must also release the penetrant readily to the aquesous milieu of the viable epidermis. This process could be hindered by an excessively unfavourable partition coefficient or by the extremely low water solubility of a penetrant.