An abnormality in sebaceous function in phenylketonuria.
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The sebum excretion rate has been found to be increased in female patients with phenylketonuria. This may be related to a depletion of midbrain dopamine and release of the sebotrophic hormone. (+info)
Disposition of cocaine in skin, interstitial fluid, sebum, and stratum corneum.
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The aim of this study was to determine whether or not the skin acts as a reservoir for cocaine. Cocaine-d5 (1 mg/kg) was administered to five nondependent, cocaine-experienced volunteers. Skin tissue, interstitial fluid, sebum, stratum corneum, and plasma were collected for 72 h after drug administration. Cocaine and benzoylecgonine (BE) levels were determined using GC-MS. Cocaine concentrations peaked in plasma at 1 h after administration, with pharmacokinetic parameters (t(1/2), CL, Vd) also in the expected ranges. In skin, cocaine levels peaked around 1.5 h after administration and became undetectable by 6 h. A correlation was found between the plasma and skin AUC for cocaine (R = 0.99, p = 0.006, N = 4). BE was not detected in skin. In interstitial fluid (N = 4), cocaine concentrations peaked around 5 h after drug administration and were undetectable by 24 h. BE peaks varied between 2 and 24 h and were not detectable at 48 h. In sebum, cocaine levels peaked between 3 and 24 h. BE was found in three samples between 12 and 24 h. In stratum corneum, cocaine was measurable in only one sample from one subject. These findings suggest that skin does not act as a reservoir for cocaine. Rather, cocaine appears to be distributed rapidly to the skin and eliminated, following a time course similar to that of plasma. (+info)
Thyroid disease and sebaceous function.
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Sebum excretion rates (SER) were measured before and after treatment in patients with hypothyroidism and thyrotoxicosis. The mean SER in the former was significantly less than that in normal controls but there was no correlation between SER and the severity of the disease as indicated by serum thyroid-stimulating hormone levels. After treatment with L-thyroxine the SER increased but remained subnormal. By contrast the SER was not increased in patients with thyrotoxicosis and it was unaffected by treatment. The human sebaceous gland seems to respond to thyroid hormone mainly in the hypothyroid range. (+info)
Human skin condition and its associations with nutrient concentrations in serum and diet.
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BACKGROUND: Nutritional factors exert promising actions on the skin, but only scant information is available on the modulating effects of physiologic concentrations of nutrients on the skin condition of humans. OBJECTIVE: The objective was to evaluate whether nutrient concentrations in serum and diet are associated with the skin condition of humans. DESIGN: A cross-sectional study was conducted in which data on serum concentrations of nutrients, dietary intake of nutrients, and the hydration, sebum content, and surface pH of skin were obtained from 302 healthy men and women. Skin condition was measured with the use of noninvasive techniques. Dietary intake was assessed with 2 complementary food-frequency questionnaires. Multiple regression analysis was used to evaluate associations of serum vitamins and carotenoids and of dietary micro- and macronutrients with skin condition. RESULTS: After adjustment for potential confounders, including sex, age, and smoking, statistically significant associations were shown in the total population between serum vitamin A and skin sebum content and surface pH and between the dietary intake of total fat, saturated fat, monounsaturated fat, and skin hydration. Monounsaturated fat intake was also associated with surface pH. Associations between serum beta-cryptoxanthin and skin hydration and between surface pH and fluid and calcium intakes were observed in men only. CONCLUSION: Several associations between nutrients in serum and diet and skin condition were observed, indicating that changes in baseline nutritional status may affect skin condition. (+info)
Identification of the delta-6 desaturase of human sebaceous glands: expression and enzyme activity.
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Delta-6 desaturase, also known as fatty acid desaturase-2 (FADS2), is a component of a lipid metabolic pathway that converts the essential fatty acids linoleate and alpha-linolenate into long-chain polyunsaturated fatty acids. Isolation of Delta-6 desaturase/FADS2 cDNA from human skin predicts an identical protein to that expressed in human brain and Southern analysis indicates a single locus, together suggestive of a single Delta-6 desaturase/FADS2 gene. Within human skin, Delta-6 desaturase/FADS2 mRNA and protein expression is restricted to differentiating sebocytes located in the suprabasal layers of the sebaceous gland. Enzymatic analysis using CHO cells overexpressing human Delta-6 desaturase/FADS2 indicates catalysis of a "polyunsaturated fatty acid type" reaction, but also an unexpected "sebaceous-type" reaction, that of converting palmitate into the mono-unsaturated fatty acid sapienate, a 16-carbon fatty acid with a single cis double bond at the sixth carbon from the carboxyl end. Sapienate is the most abundant fatty acid in human sebum, and among hair-bearing animals is restricted to humans. This work identifies Delta-6 desaturase/FADS2 as the major fatty acid desaturase in human sebaceous glands and suggests that the environment of the sebaceous gland permits catalysis of the sebaceous-type reaction and restricts catalysis of the polyunsaturated fatty acid type reaction. (+info)
Ultraviolet a induces generation of squalene monohydroperoxide isomers in human sebum and skin surface lipids in vitro and in vivo.
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At the outermost surface of human skin, skin surface lipids are first-line targets of solar ultraviolet radiation. Therefore, we hypothesized that ultraviolet A and ultraviolet B irradiation induce photo-oxidation of skin surface lipids. To test this, sebum samples were collected from facial skin of 17 healthy volunteers, weighed, and immediately irradiated with either ultraviolet B or ultraviolet A. Squalene, the major sebum lipid, as well as photo-oxidation products were identified in sebum lipid extracts by high-performance liquid chromatography analysis. Upon ultraviolet A exposures squalene was depleted in a concentration-dependent manner, whereas an unidentified sebum lipid photo-oxidation product was detected. Using high-performance thin layer chromatography, high-performance liquid chromatography, atmospheric pressure chemical ionization mass spectrometry, and nuclear magnetic resonance, unidentified sebum lipid photo-oxidation product was identified as a mixture of squalene monohydroperoxide isomers. Squalene monohydroperoxide isomers purified from sebum were identical with squalene monohydroperoxide isomers synthesized by preparative photo-oxidation of squalene. Squalene monohydroperoxide isomers were formed even after small suberythematogenic doses of ultraviolet A (5 J per cm2). Whereas physiologic baseline levels of squalene monohydroperoxide isomers in human skin were only slightly above detection limits, squalene monohydroperoxide isomer levels were strongly increased by suberythematogenic doses of ultraviolet A both in vitro and in vivo. High-performance liquid chromatography results could be complemented by a straightforward thin layer chromatography method for rapid screening of lipid peroxide formation in human sebum/skin surface lipids. In conclusion, specific squalene monohydroperoxide isomers were identified as highly ultraviolet A sensitive skin surface lipid breakdown products that may serve as a marker for photo-oxidative stress in vitro and in vivo. (+info)
Inducible mEDA-A1 transgene mediates sebaceous gland hyperplasia and differential formation of two types of mouse hair follicles.
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EDA splice isoforms EDA-A1 and EDA-A2 belong to the TNF ligand family and regulate skin appendage formation by activating NF-kappa B- and JNK- promoted transcription. To analyze their action further, we conditionally expressed the isoforms as tetracycline ('Tet')-regulated transgenes in Tabby (EDA-negative) and wild-type mice. Expression of only the mEDA-A1 transgene had two types of effects during embryogenesis: (1) determinative effects on sweat glands and hair follicles. In Tabby mice, one type of hair follicle ('guard hair') was restored, whereas a second type, the dominant undercoat hair follicle ('zigzag') was not; furthermore, the transgene sharply suppressed zigzag hair formation in wild-type mice, with the overall numbers of back hair follicles remaining the same; and (2) trophic effects on sebaceous and Meibomian glands. Marked hyperplasia resulted from expansion of the sebocyte-producing zone in sebaceous glands, with particularly high expression of the transgene and the replication marker PCNA, and correspondingly high production of sebum. The phenotypic effects of mEDA-A1 on sebaceous glands, but not on hair follicles, were reversed when the gene was repressed in adult animals. The results thus reveal both initiating and trophic isoform-specific effects of the EDA gene, and suggest a possible balance of isoform interactions in skin appendage formation. (+info)
Effect of oral contraceptives on sebum excretion rate.
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Oral contraceptives containing a high dose of oestrogen reduce the sebum excretion rate (SER) and improve acne vulgaris, but more progestogenic preparations may exacerbate acne. The effect on the SER of several oral contraceptives with varying progestogenic potencies was studied in 81 women. The predominantly progestogenic pills (Eugynon 30, Gynovlar) produced no significant change in SER, whereas the rate in women taking a more oestrogenic pill (Minovlar) was significantly reduced compared with the rate in controls. Progestogens therefore do not exacerbate acne by inducing seborrhoea, but in the doses we studied they nullified the inhibitory effect of oestrogens on the sebaceous glands. Acne-prone women who require an oral contraceptive should be given a predominantly oestrogenic preparation. (+info)