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We studied by the Sebutape technique variations in the sebum excretion and in the number of active sebaceous glands during 3 consecutive menstrual cycles. In seborrheic women we found cyclic changes with a maximum sebum excretion during the week before menstruation. In women with a low sebum production, no changes were found.
Newborn Sprague-Dawley rats of both sexes were treated with 28 micrograms thyroxine (T4) daily for the first week of life. At the age of 80 days, the secretion rate of sebum was measured from the amount of skin-surface lipids extractable by acetone and which had been produced during 2 days. Treatment with such excess amounts of T4 during the early postnatal period significantly reduced the production of sebum in both male and female rats when compared with control rats and with rats deprived of food early in life. The thyroid, the pituitary gland, the testes and the seminal vesicles were significantly smaller but the weights of the ovaries and uteri remained relatively unaffected. There was a similar ratio of sex difference in the rate of sebum secretion irrespective of treatment. It is suggested that a reduction of sebaceous response in rats made thyrotoxic with large doses of T4 early in life was probably due to a decreased secretion of thyroid hormone which is required to maintain normal activity of the sebaceous glands.
In an investigation into the effect of short-term exposure to different temperatures and humidities on the sebaceous glands of Ayrshire calves it was concluded that temperature had no appreciable effect on sebum output or its fatty acid composition. At a low humidity, however, the cutaneous outputs of palmitic and myristic acids were higher. On prolonged exposure to a warm environment, a higher output of sebum occurred together with an increase in the percentage of linoleic acid in the sebum.
We determined terbinafine levels in serum, stratum corneum, dermis-epidermis (without stratum corneum), hair, sebum and eccrine sweat before, during and after 250 mg doses orally to volunteers once daily. Terbinafine is concentrated rapidly in stratum corneum (up to 9.1 micrograms/g of tissue) primarily by diffusion from the vascular system through the dermisepidermis. It also reaches high concentration in sebum (up to 45.1 micrograms/ml) after several days and continue to concentrate in sebum for up to two days after discontinuation of drug. Hair concentration reach levels of 2.6 micrograms/g of tissue indicating high drug levels in and around the hair follicle. It is not found in sweat. Plasma levels range between 0.1 and 1.0 micrograms/ml. There is a tenfold accumulation of drug in stratum corneum by day 2. Elimination of drug from tissue occurs with a half-life of 4 to 5 days and with the potential for drug levels above fungicidal concentrations for dermatophytes for more than 3 weeks. The tissue pharmacokinetic profile of terbinafine is similar to that of another lipophilic drug, itraconazole, but is very different from ketoconazole and griseofulvin. Higher levels of terbinafine are achieved than of either of the imidazoles and remain longer than griseofulvin.
Topical corticosteroids are widely used in cutaneous diseases. Although their mode of action on different skin compartments has been documented, little is known about their effects on the human sebaceous gland. We investigated the effects of two corticosteroids of differing potency on the excretion of sebum by means of two validated techniques: the Sebutape and the Lipometre. This study was conducted on the forehead skin of normal healthy subjects. The results obtained with both techniques correlated well. The application of both corticosteroids during a 4-week period led to a significant decrease in sebum excretion. This decrease was more pronounced with the more potent corticosteroid (Dermovate). In the light of these findings, it is likely that topical corticosteroids exert an anti-proliferative action upon the sebaceous cells in a similar manner to their effect in other skin compartments.
The kinetics of sebum excretion on the forehead of volunteers were measured over a period of at least 7 h. The transmission data obtained by the ground glass method were transformed into weight (sebum/cm2). The excretion time function can be described by the equation: w = A . (1 - B . e -C.t). This nonlinear function is typical for modes of excretion in the biological field. Regulation of sebum excretion is probable. Objections against such regulation by feedback were discussed.
Experiments were conducted to determine if testosterone influences sebum output (SO) and composition (SC) in different genotypes of cattle. There were significant breed differences in plasma testosterone levels and SO but no relationship was established between the two variables. Castration of neonatal and adult bulls did not affect their subsequent SO or SC. Testosterone treatment of steers failed to change SO. There were no differences in SO or SC between bulls and heifers. The results showed that testosterone does not influence sebum production in bovines and that there was a strong genetic control over SO independent of sex.
Thin-layer chromatography and infrared reflectance spectroscopy were compared as methods for measuring sebum composition. Solutions of varying known concentrations of free fatty acids and triglycerides were analyzed by both methods. Skin surface lipid samples were similarly analyzed. Infrared spectroscopy produced more variable data than thin-layer chromatography with photodensitometry. This was particularly true at low concentrations of free fatty acids. It is concluded that thin-layer chromatography with photodensitometry is a more accurate method for the measurement of sebum composition.
There is evidence that anti-androgens may help in the treatment of acne vulgaris. We therefore performed a double-blind trial to assess the effect of topically applied progesterone on sebum excretion rate. Thirty-eight patients took part in the trial which was for 3 months. The preparation had no effect in males. However, a significant reduction in sebum excretion rate was found in females, the effect being maximal at the end of the second month. There was a significant loss of effect at the end of the third month and this was not related to deterioration of the progesterone preparation.
Direct measurements of sebum with the Sebumeter were used in a patient with a benign androgen-producing tumor of the ovary. Androgen levels fell immediately after surgery, whereas the markedly elevated sebum levels found preoperatively dropped to normal after a delay of more than 2 weeks. Therefore, the Subumeter, due to its simplicity, may be useful for the preliminary screening and follow-up of patients with hyperandrogenic states.
It is currently agreed that ambient temperature influences the sebum excretion rate. By using the Sebutape technique we have confirmed this concept, which is related to an increased delivery of sebum to the surface of the skin without an increment in the number of active sebaceous follicles.
A controlled study of the "immune reaction to sebum" pathogenesis of keloids was carried out at the University College Hospital, Ibadan, Nigeria; on 22 humans using a homogenate solution of liquid paraffin and vernix caseosa from neonates. The 22 human volunteers comprised two groups, 11 of which were keloid formers and 11 non keloid formers. 0.1cc of sterile liquid paraffin was injected intradermally into the anterior aspect of the left forearm. The mean reaction in keloid formers was 11.55mm while in non keloid formers, it was 8.18mm. Although a higher reaction was demonstrated in this study, in keloid formers, this was found not to be significant (p less than 0.05), thus suggesting that sebum may not be an important factor in the pathogenesis of keloid.
1) A relatively large quantity of branched chain and odd-carbon-number fatty acids were found in human sebum. 2) These acids were present in each lipid fraction (cholesterol ester, triglyceride and free fatty acid) of sebum. 3) In the triglyceride molecule, these acids were found mainly on the 2-position.
The chemical composition of the gland-pad sebum of gerbils of both sexes is analysed using gas-liquid chromatographical and mass spectroscopical techniques and compared with the lipids from distal skin areas. Cholesterol esters, with (omega-1)-methyl-substituted fatty acids as acidic constituents, were shown to occur in the gland-pad sebum of both sexes in high concentrations, whereas cholesta-3,5-diene could be detected in the males only.
Various tetracyclines and erythromycins have been used rather empirically for the systemic treatment of acne vulgaris for more than a decade. It has been impossible to accurately evaluate clinically the numerous derivatives and to compare their effectiveness with other antibiotics such as clindamycin. As a substitute for this approach, this present study ranks these antibiotics, when given orally, as to their effectivensss in suppressing the fatty acids in sebum in normal volunteers. As a group, the tetracyclines were more effective than the erythromycins in decreasing the fatty acids, but clindamycin was significantly more potent than either.
Cimetidine, 1g orally per day, partially inhibited sebum excretion in patients with acne. Whether this was the result of H2-receptor blockade or an antiandrogen action is unknown.
Cholesterol esters (CE) having fatty acids of more than 18 carbons are a prominent feature of fetal skin surface lipid (vernix caseosa), but are a minor component of adult lipid. The difference may be related to the fact that fetal sebaceous glands generally synthesize little lipid. If so, it would be expected that prepuberal children, who also have very inactive glands, would secrete CE with a large proportion of very-long-chain fatty acids. To test this conjecture, skin surface CE from young children were isolated and analyzed. Sebum was extracted from the hair of 38 children, aged six to nine. To obtain a measure of sebaceous lipogenesis, the class composition of the lipid was determined by quantitative thin-layer chromatography and the ratio of wax esters/[cholesterol + cholesterol esters] (WE/[CH + CE]) was calculated. CE were then isolated from the lipid and hydrolyzed. The freed fatty acids were converted to fatty acid methyl esters (FAME) and analyzed by capillary gas chromatography to determine the proportion with more than 18 carbons. FAME from five of the subjects were then separated into saturated and monounsaturated fractions and analyzed again by gas chromatography to identify chain types. Ratios of WE/[CH + CE] ranged from 0.08 to 2.8 in the subjects. The proportion of CE FAME with more than 18 carbons ranged from 15 to 72%, with the highest proportion being found in the children with the lowest WE/[CH + CE]. The saturated FAME were mostly iso- or anteiso-branched, whereas the monounsaturated FAME were mostly straight-chain extension products of 16: 1 delta 9 or 18: 1 delta 9.
The sebum excretion rate (SER) was measured in fifty-five patients with rosacea and 126 control subjects. The mean SER in the patients with rosacea was not increased, nor was there any correlation between SER and severity of rosacea. Our data suggest that seborrhoea plays no part in the pathogenesis of rosacea.