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60 male Syrian hamsters were treated on one ear with 2.5% selenium disulfide in a surfactant base and on the other ear with the same surfactant base. After treatment 15 animals were investigated by 3H-thymidine autoradiography, 15 animals by the colcemid method and 15 animals by the in vivo double labelling technique with 3H- and 14C-thymidine. In 15 animals the porportion of labeled cells was determined which still had contact with the basal lamina in the sebaceous gland 6 days after 3H-thymidine injection. Besides an increase in sebaceous gland size and in cell proliferation, a shortening of the S phase and a reduction of the labeled sebaceous gland cells which still have contact with the basal lamina of the sebaceous gland 6 days after 3H - thymidine injection were determined.

24 male and 24 female syrian hamsters were treated with antiestrogen Tamoxifen for 21 days (dosage 5, 50, 200 and 800 microgram/d, respectively). For control, 6 male and 6 female animals remained untreated. After having finished this treatment, we performed double-labelling autoradiography with 3H- and 14C-thymidine on all animals, under in vivo-conditions. The number of single labelled 3H-cells has been related to cell proliferation. The quotient " double labelled cells/single 3H-labelled cells " served as a measure for the duration of the S-phase. In addition, we measured the sebaceous gland volume. No essential influence on the parameters could be found. Therefore, we have to assume that the antiestrogen Tamoxifen does not have an essential effect on cell kinetics in the sebaceous gland.

It was shown by in vitro studies that 8-methoxypsoralen (= 8 MOP) alone and UVA irradiation alone produces relatively little inhibition of the growth of Propionibacterium acnes and Propionibacterium granulosum, whereas a combination leads to an intense suppression of bacterial growth. It was further demonstrated by in vivo studies on 14 subjects that local treatment with 8 MOP and UVA significantly reduces the propionibacteria in the pilosebaceous duct. These results afford a possible explanation for the well known favorable effect of photochemotherapy on acne vulgaris. In addition, they contribute to explaining the drier appearance of the skin after photochemotherapy.

By using the colcemid method, the presence of a diurnal variation for the mitosis index was confirmed, showing a definite minimum during the night in the sebaceous gland of the Syrian hamster ear. Furthermore, the number of all labelled cells and the quotient "single-labelled 14C-cells + double-labelled cells/single-labelled 3H-cells" determined with double-labelling autoradiography ([3H] and [14C]thymidine) seem to be subject to rhythmic fluctuations, although statistical support for this observation is lacking. The parallelism of the rhythmic variations in the epidermis and in the sebaceous glands is striking.

Fifteen male Syrian hamsters were treated for 10 days with 3 x 20 mg zinc sulfate (corresponding to 13,5 mg elementar Zn/d) by means of a stomach tube. Fifteen control animals remained untreated. After treatment the size of sebaceous glands was measured with th plate integration method and the mitotic rate was determined with the colchicine method in both treated and control animals. Zinc therapy significantly increases the size of the sebaceous glands, as well as the cell proliferation in the sebaceous glands.

In 24 persons with a severe inflammatory acne and 48 control subjects, bacteria were sampled from the sebaceous gland exretory ducts with the glass sampling head method according to Holland et al. After anaerobic culture bacterial counts were performed. The total numbers of P. acnes and the frequency of detection of P. granulosum were determined. The bacterial counts of P. acnes were almost idendical in the two collectives. P. granulosum was detected at a significantly higher frequence in the acne patients than in the control subjects. It can be assumed on the basis of the results that an increase in the bacterial counts of P. acnes is not to be regarded as a pathogenetic factor in the inflammatory acne of older patients. On the other hand, they suggest that P. granulosum may have an appreciable role in acne.

A preparation of dexamethasone 0.02% in Eutanol G (n octyldodecanol) was applied once daily for three weeks, to the right side of the forehead of 25 male healthy test subjects. Eutanol G without dexamethasone was applied in the same way to the left side of the forehead. Before and at the end of the treatment period bacteria were removed from the pilo-sebaceous ducts by the method of Holland et al. [8]. Bacteria that grew under anaerobic conditions were evaluated quantitatively. Dexamethasone induced a significant increase in P. acnes, in all Propionibacteria and in the total bacterial count. The importance of these findings is discussed in relation to the development of steroid acne.

30 male Syrian hamsters were X-ray irradiated on 1 ear with 500 rad (Dermopan 2; setting 3; tissue half value thickness, 7.5 mm). 30 other animals were treated locally on one ear with an emulsion containing 0.15% 8-methoxypsoralen and then with UV A (10 treatments in 23 days; total UV A dose, 5.0 J/cm20. The other ear served as control. An in vivo double-labelling autoradiography with 3H- and 14C-thymidine was carried out on half of the animals of each group. The other half was administered 3H-thymidine and the number of labelled cells still in contact with the basal lamina of the sebaceous gland after 6 days was determined. The effects of X-ray irradiation and photochemotherapy are identical. Cell proliferation in the sebaceous gland was reduced, the length of the S phase was shortened, and the number of marked cells still in contact with the basal lamina after 6 days was decreased.

An unspecific cream vehicle containing 1% erythromycin base was applied once a day for 10 days to one side of the forehead of 16 healthy subjects and the same vehicle without the active agent to the other side. Using the same procedure a solution containing 1.19% clindamycin phosphate (corresponding to 1% clindamycin base) and the corresponding unspecific vehicle was administered to another group of 17 healthy males. Prior to the treatment and after the end bacteria were obtained from the pilosebaceous ducts by means of a special sampling technique. Both ointments containing the antibiotics lead to a significant reduction of the bacterial growth in the pilosebaceous ducts regardless of whether evaluation is made of the total bacterial count or of Propionibacteria. Thus, it could be demonstrated that topical application enables some antibiotics to penetrate into the pilosebaceous duct in an adequate concentration to ensure antibacterial effectiveness if a suitable vehicle is used.

The cell kinetics of the sebaceous gland of the hamster ear were analysed in untreated animals, in animals treated with cyproterone acetate, and in animals treated with estradiol. Both active substances lead to a reduction in the size of the sebaceous gland (measurement with the integration plate), to a reduction of mitoses (colcemide method), to a reduction in the 3H-thymidine labelling index, to a prolongation of the S-phase (double labelling technique with 3H- and 14C-thymidine), and to a decrease in the number of cells labelled with 3H-thymidine which remain in contact with the basal lamina of the sebaceous gland 6 days after application of the isotope. The results indicate that, like cyproterone acetate, estradiol reduces the effect of androgens on cell kinetics in the sebaceous gland under the test conditions chosen, even if in an entirely different way.

Groups of 15 guinea pigs and 10 Syrian hamsters were treated with 5-fluorouracil (Fluoro-uracil "Roche") for 8, 22, and 36 days, respectively. 15 guinea pigs and 10 Syrian hamsters remained untreated. At the end of the experiment the hair root status of the guinea pig and the 3H-thymidine labelling index of the sebaceous glands and epidermis on the Syrian hamsters were determined. 5-Fluorouracil leads to a gradual reduction of both the 3H-thymidine labelling index in the epidermis and the sebaceous glands and the amount of anagenetic hair. The effect is slow at the onset, gradually increases, and is still increasing after 3 weeks of treatment. The reduction in the number of labelled cells is significantly larger in the epidermis than the sebaceous glands.

By using the Syrian hamster ear model it is shown that cimetidine inhibits cell proliferation in the sebaceous gland. Furthermore, the S phase of sebaceous gland cells is lengthened and the number of labelled cells still in contact with the basal lamina of the sebaceous gland 6 days after isotope application related to the total number of labelled sebaceous gland cells is reduced. The effect of cimetidine is absolutely identical with that of cyproterone acetate, but is quite different from that of the nonhormonal sebosuppressive agent benzoyl peroxide.