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The cell cycle has been determined in eight in-patients with psoriasis. The cell cycle time for the germinative cell compartment has been found to be 91 h, and the turnover time for the epidermal compartment, beneath the keratin layer to be 120 h (5 days). The duration of the S phase (DNA synthesis) has been found to be 10 h, and that for mitosis 30 mm. If it is accepted that the turnover time for the keratin layer is 2 days, then the turnover time for the epidermis in psoriasis is 7 days, and not 3-4 days as previously described. [ABSTRACT FROM AUTHOR]

Biopsies have been taken from the involved and uninvolved skin of eleven patients with psoriasis and the normal skin of six patients without psoriasis, 1 h after in vivo injection of 10 μCi of 3H-thymidine. Mitotic counts and counts of labelled cells (synthesizing DNA) after autoradiography have been carried out. The ratio of mitoses to labelled cells was 1 : 25 in clinical psoriasis, 1 : 190 in uninvolved psoriatic epidermis and 1 : 450 in normal epidermis. The number of labelled cells in clinical psoriasis was approximately 12 times greater than normal epidermis. However, the number of labelled cells in uninvolved psoriatic epidermis was approximately twice that of normal. These results imply an alteration in the components of the cell cycle in both involved and uninvolved psoriatic epidermis. [ABSTRACT FROM AUTHOR]

The effect of betamethasone 17-valerate, fluclorolone acetonide, fluocinolone acetonide and formocortal on the clinical and histological features and mitotic counts of psoriatic epidermis have been compared. In five of the six patients studied the preparations were used under polythene occlusive dressings. Biopsies were carried out before treatment and then at varying intervals for a week. All the four steroid preparations appeared effectively to reverse the psoriatic lesion. Betamethasone 17-valerate and fluocinolone acetonide were found to give similar and slightly superior results to fluclorolone acetonide and formocortal on the criteria used in this study. It would appear that at the present time more potent topical steroids would not be of any advantage in the treatment of psoriasis. Drugs with a more selective action on the psoriatic process and without the steroid effect on collagen are required. [ABSTRACT FROM AUTHOR]