Stratum corneum human abdominal

The effectiveness of the stratum corneum in blocking the passage of chemicals varies from one part of the human body to another. It is particularly difficult for chemicals to cross the palms of the hands and soles of the feet, but they get by the scrotum fairly easily. Abdominal skin is of intermediate effectiveness in preventing absorption. Age and sex also influence rates of dermal absorption, and some species... 

A study on human abdominal skin showed that fluorescent dye embedded in a bilayer made from gel-state PC was taken up by the skin,24 but the dye penetrated only into stratum corneum. The results of this experiment are illustrated in Figure 23.2. Similar results were reported also by others.22,23 35 The tolerance of skin of 20 volunteers to the gel-state PCs was studied in comparison to some common emulsifiers. Nine emulsifiers and gel-state PC were tested in the Duhring Chamber using test protocol of Frosch and Kligman.36 Based on scaling and erythema, gel-state PCs were the only substances that showed no irritation potential.37 The results are shown in Figure 23.3. Reviewed recently were also the toxicological aspects of the use of gel-state PC in a topical application.7... 

A sorption isotherm on excised human abdominal stratum corneum (female, age 68) is presented in Figure 9. The data were obtained on separate pieces of skin which were initially dried and then exposed to an air stream with a given RH uptake was followed until equilibrium was reached. Values of D calculated from half-time data for each humidity interval were 1.37-5.10 X 10 cm /sec. Scheuplein and Blank (16) reported a value of 5 X 10 cm /sec for human stratum corneum. The range of our values would indicate that D is concentration dependent. Full details will be reported in the future. 

Recently Al-Saiden et al [181] examined the thermal transitions in desiccated stratum comeum membranes of neonatal rats, rabbits and adult abdominal human skin. Four endothermic transitions were observed at 39-45°C, 55-58°C, 68-74°C and 77-86°C. The transitions at 39-45°, 68-74° and 77-86°C were attributed to phase charges in the intercellular lipid bilayers. A fifth transition at 48° was seen only in the neonatal rabbit stratum corneum and was attributed to lipid melting. 

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