In Vivo Methods

In 1940, Schwartz et al. [18] introduced an in vivo method to evaluate the efficacy of a vanishing cream against poison ivy extract using visual erythema on human skin. The test cream was an effective prophylaxis against poison ivy dermatitis when compared with unprotected skin.

Lupulescu and Birmingham [19] observed the ultrastructural and relief changes of human epidermis after exposure to a protective gel, acetone, and kerosene on humans. Unprotected skin produced cell damage and a disorganized pattern in the upper layers of epidermis. Application of a protective agent before to solvent exposure substantially reduced the ultrastructural and relief changes of epidermis cells.

Lachapelle and co-workers [3, 20-23] used a guinea pig model to evaluate the pro

tective value of BC and/or gels by laser Doppler flowmetry and histological assessment. The histopathological damage after 10 minutes of contact to toluene was mostly confined to the epidermis, whereas the dermis was almost normal. The dermal blood-flow changes were relatively high on the control site compared with the gel-pretreated sites.

Frosch et al. [1, 8, 9, 24, 25] developed the repetitive irritation test (RIT) in the guinea pig and in humans to evaluate the efficacy of BC by using a series of bioengineering techniques. The cream-pretreated and -untreated test skin (guinea pig or humans) was exposed daily to the irritants for 2 weeks. The resulting irritation was scored on a clinical scale and assessed by biophysical techniques' parameters. Some test creams suppressed irritation with all test parameters, some failed to show such an effect, and some even exacerbated the irritation [9].

Zhai [2] used an in vivo human model to measure the effectiveness of BC against dye-indicator solutions: methylene blue in water and oil red O in ethanol, which are representative of model hydrophilic and lipophilic compounds. Solutions of 5% methylene blue and 5% oil red O were applied to untreated and BC-pretreated skin with the aid of aluminum occlusive chambers for 0 and 4 hours. At the end of the application time, the materials were removed, and consecutive skin-surface biopsies (SSB) obtained. The amount of dye penetrating into each strip was determined by colorimetry. Two creams exhibited effectiveness, but one cream enhanced the cumulative amount of dye.

Zhai et al. [5] introduced a facile approach to screening protectants in vivo in human subjects. Two acute irritants and 1 allergen were selected: 1) sodium lauryl sulfate (SLS), representative of irritant household and occupational contact dermatitis, 2) the combination of ammonium hydroxide (NH4OH) and urea to simulate diaper dermatitis, and 3) Rhus to evaluate the effect of model protective materials. Test materials were spread onto test area, massaged, allowed to dry for 30 minutes, and reapplied with another 30-minute drying period. The model irritants and allergen were applied with an occlusive patch for 24 hours. Inflammation was scored with an expanded 10-point scale at 72 hours after application. Most test materials statistically suppressed the SLS irritation and Rhus allergic reaction rather than NH4OH and urea-induced irritation.

Wigger-Alberti et al. [26] determined which areas of the hands were likely to be skipped on self-application of BC by fluorescence technique at the workplace. Results showed the application of BC was incomplete, especially on the dorsal aspects of the hands. Brief data of recent experiments of BC are summarized in Table 1.

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

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