Human skin equivalents are an excellent tool to study the effect of moisturizers on the water distribution in the stratum corneum.

In this study, the mode of action of moisturizers on the level of water in the stratum corneum was studied using cryo-scanning electron microscopy. As model for dry skin, we used human skin equivalents (HSEs) generated at 93% or 60% relative humidity (RH). During the generation of the HSEs, the moisturizers were applied during a period of maximal 2 weeks.

Lipophilic and hydrophilic moisturizers show different actions on human skin as revealed by cryo scanning electron microscopy.

To study the mode of action of moisturizers on human skin, hydrophilic moisturizers in water and neat lipophilic moisturizers were applied on excised skin for 24 h at 32 degrees C. Samples of the treated skin were subsequently visualized in a cryoscanning electron microscope. The stratum corneum (SC) appeared as a region of swollen corneocytes (the swollen region) sandwiched between two layers of relatively dry corneocytes (the upper and lower non-swelling regions respectively).

Water distribution and natural moisturizer factor content in human skin equivalents are regulated by environmental relative humidity.

Human skin equivalents (HSEs) show great similarities to human native skin. However, one of the key processes impaired under in vitro conditions is desquamation. Desquamation involves the degradation of the corneodesmosomes, in which various enzymes participate.

Temperature-induced changes in structural and physicochemical properties of vernix caseosa.

The skin of the third trimester fetus and early newborn exhibits a complex, multifunctional, highly hydrated but viscous skin-surface biofilm called vernix caseosa (VC). During birth, VC undergoes a substantial change from an aqueous and warm surrounding into a gaseous and colder environment postnatally. The aim of this study was to investigate the structural and physicochemical changes in VC, which accompany physiologically relevant variations in environment parameters, such as temperature and humidity.

Interaction of lipophilic moisturizers on stratum corneum lipid domains in vitro and in vivo.

Dry skin symptoms such as scaling and itching are often treated with lipophilic moisturizers. The aim of this study was to investigate the effect of lipophilic moisturizers on the stratum corneum (SC) ultra-structure and lipid organization. Lipophilic moisturizers were applied on the forearms of 4 healthy volunteers for 3 h.

Visualization studies of human skin in vitro/in vivo under the influence of an electrical field.

The aim of this study was to investigate the local changes in the ultrastructure of human skin after iontophoresis, using cryo-scanning, transmission and freeze fracture electron microscopy in human skin in vitro and in vivo. Human dermatomed skin was subjected to passive diffusion for 6 hours followed by nine hours of iontophoresis at 0.5 mA/cm2.

New insights into ultrastructure, lipid composition and organization of vernix caseosa.

The upper layer of the epidermis, the stratum corneum (SC), is very important for skin barrier function. During the last trimester of gestation, the SC of the fetus is protected by a cheesy, white biofilm called vernix caseosa (VC). VC consists of water-containing corneocytes embedded in a lipid matrix and the basic structure shows certain similarities with the SC.

The in vivo and in vitro interactions of elastic and rigid vesicles with human skin.

Elastic vesicles are the most novel development in vesicular systems design for dermal and transdermal drug delivery. However, interactions between these vesicles and human skin are not yet fully understood. In this study, the in vivo and in vitro interactions between elastic-, rigid vesicles and micelles with human skin were investigated.

Alkaloids from Strychnos floribunda.

From Strychnos floribunda stem bark extracts, the alkaloids bisnordihydrotoxiferine, akagerine, decussine, rouhamine, Strychnocarpine, desacetylisoretuline and isorosibiline were isolated as well as a mixture of the sterols beta-sitosterol, stigmasterol and campesterol. Isorosibiline is a new indole alkaloid derived form desacetylisoretuline, having C-16 configuration inverted to that of rosibiline.