DNS-Synthese und Hyperplasie der Epidermis nach Hornschichtabri� und Salben-Applikation

Effects of dermatitis, stripping, and steroids on the morphology of corneocytes. A new bioassay

This study was designed to investigate the effects of increased or decreased epidermal turnover on the morphology of human corneocytes. The desquamating portion of the stratum corneum was sampled with the detergent scrub technique using Triton X-100. The following parameters were measured: size (surface micron2), shape (regular, irregular), nuclear inclusions, trabeculae, and numerical counts. Specimens were obtained from adult males with allergic contact dermatitis (N=18); with tretinoin-induced dermatitis (N=11); after cellophane stripping (N=11); and after treatment of these conditions with topical steroids (N=40). Data from 250,000 cells were analyzed statistically. The reproducibility of the method is good (r=0.934). Corneocytes from skin of patients with allergic contact dermatitis differed from those of normal skin: they were 15% smaller and of irregular shape with asymmetrical trabeculae; 50% were nucleated and about 3 times as many cells were collected per cm2 skin surface. Tretinoin and stripping produced similar but more pronounced effects. Topical steroids significantly improved all parameters (p less 0.01). Betamethasone-17-dipropionate was more effective than the valerate. This bioassay permits sensitive measurements of corneocyte morphology in conditions with altered epidermal cellular kinetics. It provides a method to evaluate steroid effectiveness.

[Quantitative histometric investigations on the epidermis and corium of rat paw after experimental inflammation (author's transl)]

The epidermis and corium of rat right hind paw were investigated both histologically and histometrically after a subplantar injection of aerosil, formalin, carrageenin or Freund's complete adjuvant. The thickness of the epidermis and corium was determined on 5 rats respectively at 12 different times between 0.5 and 480 h post-treatment. Paw swelling was measured plethysmometrically on living rats. The left paw of untreated rats as well as the saline-injected and the untreated left paw of carrageenin-treated and adjuvant-treated animals respectively served as controls. Results 1. After the injection of the 4 substances, an acute inflammation developed maximally 4 to 24 h post-treatment in the corium. The thickness of the corium increased simultaneously with paw swelling. 2. Epidermal hyperplasia set in after a lag-phase of 12 h following the injection of formalin, carrageenin and adjuvant. 3. After injection of aerosil a subcutaneous oedema developed but no epidermal hyperplasia occured. 4. The formation of granulation tissue and necroses in the corium was seen only in the adjuvant-treated group 4 to 20 days post-treatment. At the same time, epidermal hyperplasia reached an absolute maximum. 5. The disturbance of nutrition and the lack of oxygen in the inflamed corium is possibly responsible for the initiation and persistence of the hyperplasia.

[Investigations on the mechanism of the activity of urea upon the epidermis (author's transl)]

As a reaction of the epidermis subsequent upon contact with urea, a thinning is ascertainable 5 days later, for which corresponding enzymological and autoradiographical findings cause to presume the DNA being the working point. Further information about the mechanism of this reaction was obtained first by short time tests, whence by means of 3H thymidine autoradiography not later than the second day after contact with urea a decreased number of cells synthesizing DNA in the stratum basale were to be secured. These findings obtained using the model of the guinea-pig's ear are also ascertainable in the human skin, an unspecified effect, also to be released by other non-electrolytes, having been excluded by controls of glucose replacing urea. The quick invasion of urea into the epidermis, deducible from the short time tests, was proved by 14C traced urea, ascertainable not later than 15 min after its contact with the skin amongst the blood - even if in little activity. Hence, the urea enters into the cutis speedily, releasing there a disturbance in the process of the epidermal proliferation, which conducts in the sequel to an epidermal thinning.