THE ADENYL CYCLASE OF SKIN I. MEASUREMENT AND PROPERTIES

A method is described for the measurement of cutaneous adenyl cyclase. Certain properties of the adenyl cyclase of guinea-pig skin have been studied; this enzyme appears to be unusual in that no stimulation of its activity by adrenalin could be demonstrated.     

A METHOD FOR DEMONSTRATION OF THE DISTRIBUTION OF SEBUM ON THE SKIN SURFACE

SUMMARY.— A method is described for demonstrating sebum secretion in precise relation to the microscopic features of the skin. It is based on a combination of the use of a replica of the skin surface and chemical demonstration of the collected lipid with osmium tetroxide. Examples are shown of characteristic patterns of sebum distribution on areas of skin rich in sebaceous glands. The technique should be useful in the study of diseases due to sebaceous glands in providing numerical data of these structures in addition to information obtained by sebum collection.     

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.     

THE EFFECT OF HEAT, pH AND ORGANIC SOLVENTS ON THE ELECTRICAL IMPEDANCE AND PERMEABILITY OF EXCISED HUMAN SKIN

SUMMARY.— The permeability of excised human skin to dimethyl sulphoxide and the effects of this solvent on water permeability are described. The results of measurements of the electrical impedance of excised human skin both before and after chemical and heat treatments are also given. Stratum corneum is shown to undergo irreversible structural changes when heated above 65°C. or incubated in aqueous media at pH < 3 or > 9. Simultaneous measurements of water permeability and electrical impedance of skin samples subjected to treatments with dimethyl sulphoxide, detergents and surfactants show that there is a good correlation (coefficient - 0·78) between the two quantities. Some organic solvents including aliphatic acids, bases, and neutral compounds are shown to produce large changes in electrical impedance, and hence, it is inferred, in water permeability. It is suggested that these changes are due to solution of skin components, loosening of the skin structure, and hence swelling and hydration of the skin. The solvent induced changes in water permeability provide an explanation for the accelerating effect of the solvents on the penetration rates of topically applied drugs.     

A MICRO METHOD FOR MEASURING THE CARBON DIOXIDE RELEASE BY SMALL SKIN AREAS

Summary.— In search for rapid routine methods for the measurement of carbon dioxide release by human skin, the authors succeeded in improving the infrared analytical method which, when carried out at 4·3 μm, yielded reliable results. Two techniques have been compared, viz. the steady state method (for larger skin areas of about 8 cm²) and the trap technique (which is less dependent on the area to be measured: 1 to 10 cm²).
With both techniques micro amounts of carbon dioxide, eliminated by very small areas of the skin and/or the sweat glands, can be determined: 2 to 100 parts/10⁶ of CO₂ 10 cm^-2 min^-1.