No abstract

summary 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 (synesizing 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.

SUMMARY 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 min. 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.

Three cases of waxy keratoses of childhood occurring in two families are described. The disorder seen in these three cases appears to be clinically and histopathologically distinct from previously described familial disorders of keratinization, which also feature multiple discrete papules.

A rapid and specific two-site, 96-well ELISA assay, available in kit format, can now quantify the effects of drugs on survival of motor neurons protein levels in cell cultures.