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With the diaminobenzidine method, endogenous peroxidase activity was demonstrated in the nuclear envelope and in the endoplasmic reticulum of non-keratinized keratinocytes and Langerhans cells of the epidermis of the newborn mouse, adult guinea pig and man. In the guinea pig all non-keratinized layers of keratinocytes, showed this enzyme activity, whereas in the two other species examined peroxidase activity was limited to the suprabasal layers. The most pronounced activity was found in the langerhans cells. The melanocytes were negative. With the same method, cytochrome c/cytochrome oxidase activity could be localized in the mitochondria of all epidermal cells of mouse and man, but not in the guinea pig.

The cytochemical expression of epidermal peroxidase and cytochrome oxidase activity was recently well documented in normal human skin.We report here its expression in basal and squamous cell carcinomas, actinic keratoses, psoriasis, allergic contact dermatitis, seborrheic keratoses, and autosomal dominant ichthyosis vulgaris. The two enzyme activities were evaluated using the diaminobenzidine method. If present, the two enzymes were always localized in the same organelles as in normal epidermis endogenous peroxidase in the nuclear envelope and endoplasmic reticulum, and cytochrome oxidase in mitochondria. In basal and squamous carcinomas, actinic keratoses and psoriasis, the keratinocytes lost their peroxidase activity, but maintained their cytochrome oxidase activity. In seborrheic keratoses, allergic contact dermatitis and ichthyosis vulgaris, the cytochrome oxidase activity was greatly reduced or abolished in keratinocytes, Langerhans' cells, and melanocytes, whereas the peroxidase activity was present as in normal epidermis. These results indicate that the two peroxidatic enzymes studied are not interrelated and alternatively suppressed by different cellular dysfunctions.

Crude extracts of Panamian plants (153 representing 28 species from 21 families) have been screened for antifungal activity against Candida albicans and Cladosporium cucumerinum. Activity was assessed in a semiquantitative fashion by bioautography on TLC plates. When tested at 100 μg, 15% of the extracts showed activity against one of the fungi, and 9% of the extracts were active against both test organisms. The most promising extracts originate from plants used in traditional medicine, such as Bursera simaruba (Burseraceae), Gliricidia sepium (Leguminosae) and Piper auritum (Piperaceae).

Data from the literature suggest that the nutritional environment can modify major metabolic functions of fungi and possibly their aggressivity towards keratinous structures. Trichophyton rubrum (TR), Microsporum canis (MC), Scopulariopsis brevicaulis (SB), Aspergillus fumigatus (AF)and Penicilliumspec. (P)were inoculated on media of different nutritional value, in presence of nail fragments. The activity of the fungi was evaluated at two and four weeks for intensity and depth of invasion of nail samples. Nail invasion was most pronounced by MC, especially when grown on rice agar or peptone agar. Nail invasion by the other fungi tested was less important, Sabouraud glucose and rice agar were most favorable. Our results indicate that nutritional factors can, at least in some fungus species, alter their rate of nail invasion. Ernährungsfaktoren können wichtige metabolische Funktionen der Pike verändern und damit auch ihr Eindringen in Keratinstrukturen. Trichophyton rubrum (TR), Microsporum canis (MC), Scopulariopsis brevicaulis (SB), Aspergillus fumigatus (AF)und Penicilliumspec. (P)wurden auf verschiedene Nährboden aufgeimpft und Nagelfragmente wurden gleichzeitig auf die Inokulationsstelle gelegt. Die Intensität und Tiefe des Nagelbefalls wurden nach zwei und vier Wochen untersucht. MCzeigte die groβte Aggressivität gegen Nagelkeratin auf Reis‐Agar und Pepton‐Agar. Die anderen Pilze waren generell weniger aggressiv; Sabouraud‐Glucose‐Agar und Reis‐Agar waren am günstigsten. An die‐sem In‐vitro‐Nagel‐Modell konnte bestätigt werden, daβ Ernährungsbedingungen die Penetrationsfähigkeit von Pilzen beeinflussen können.

Summary Monoethyl ether of hydroquinone, applied topically on black guinea pig skin, is a very potent depigmenting agent. Its action on epidermal melanocytes was studied by electron microscopy.

An electron microscopical study of skin from 2 patients with ichthyosis linearis circumflexa and trichorrhexis invaginata revealed a severe and localized disturbance of keratinization occuring at the keratotic border of figurate skin lesions. It is characterized by a marked decrease of the desmosome-tonofilament system, lack of membrane coating granules and keratohyalin, and the appearence of roundoval, electron dense bodies in the upper spinous layers. The result is a completely disorganized “stratum corneum”. We consider this unique keratinization disorder to be specific for this disease.

Electron microscopy of skin lesions from a patient with Hyperkeratosis lenticularis perstans showed formation of a compact hyperkeratotic stratum corneum which appears to be related to lack of Odland bodies in the underlying epidermis.