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Analysis of fatty acid and alcoholic components of sebaceous lipid types.
Lipids were extracted from hair, scalp wipings, ovarian dermoid cysts, and vernix caseosa and submitted to alkaline hydrolysis. Alumina chromatography applied to the unsaponifiable portions allowed for the separation of hydrocarbons, alcohols, and sterols. The fatty acids from the saponifiable mixtures were converted to the methyl esters and analyzed by gas chromatography in conjunction with mass spectrometry. This technique permitted the identification of the even, odd, iso, and anteiso fatty acid levels of the various pools. Analysis of the alcohols was afforded by gas chromatography of the acetates. Ratios were determined among the acidic and alcoholic components of each lipid class and the alcoholic constituents of each pool appeared to be increased by two C2-fragments over the average carbon number of the corresponding acid fraction. Branched components ranged higher in all alcohol mixtures as compared to the respective acids and thus, indicative of a specificity for the synthesis of a specificity for the synthesis of alcohols.
Age, breed, sex and period effects on skin biophysical parameters for dogs fed canned dog food.
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Ultrastructural changes in open comedones following treatment of cystic acne with isotretinoin.
The primary change found in cellular material expressed from open comedones of patients who had been treated with isotretinoin was disintegration of desmosomes. Consequently, there was lack of cohesion between cornified cells. A marked decrease in the quantity of sebaceous material and bacteria was also evident within the comedones.
Sebomatricoma: a unifying term that encompasses all benign neoplasms with sebaceous differentiation.
Literature regarding neoplasms with sebaceous differentiation is confusing, particularly concerning the concept of sebaceous epithelioma, accepted by some observers as a specific neoplasm but defined by others as basal cell carcinoma with sebaceous differentiation and still others as sebaceous adenoma in which undifferentiated basaloid cells predominate. From our study of 19 benign sebaceous neoplasms within this spectrum and a critical review of the literature, we conclude that (a) "sebaceous epithelioma" is a nonuseful term; (b) the term "basal cell carcinoma with sebaceous differentiation" should be used only for an otherwise conventional basal cell carcinoma with histological evidence of sebaceous differentiation; (c) "sebaceous adenoma," as described by Troy and Ackerman, represent polar ends of the spectrum of a benign neoplasm with varying degrees of sebaceous differentiation, for which we propose the term "sebomatricoma"; and (d) sebomatricoma, so defined, embraces such diverse benign neoplasms with sebaceous differentiation as superficial epithelioma with sebaceous differentiation and previously "unclassifiable" sebaceous neoplasms, often found in patients with Muir-Torre syndrome or within nevus sebaceus of Jadassohn.
Keloids: time to dispel the myths?
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Keloid pathogenesis and treatment.
BACKGROUND: Keloid management can be difficult and frustrating, and the mechanisms underlying keloid formation are only partially understood. METHODS: Using original and current literature in this field, this comprehensive review presents the major concepts of keloid pathogenesis and the treatment options stemming from them. RESULTS: Mechanisms for keloid formation include alterations in growth factors, collagen turnover, tension alignment, and genetic and immunologic contributions. Treatment strategies for keloids include established (e.g., surgery, steroid, radiation) and experimental (e.g., interferon, 5-fluorouracil, retinoid) regimens. CONCLUSION: The scientific basis and empiric evidence supporting the use of various agents is presented. Combination therapy, using surgical excision followed by intradermal steroid or other adjuvant therapy, currently appears to be the most efficacious and safe current regimen for keloid management.
Wetting of biological lipids on aqueous substrates.
We study the dynamics and final wetting state of skin lipids on water and brine by fluorescence microscopy and ellipsometry. When a lipid droplet is brought into contact with the water surface, a lipid wetting film spreads out rapidly by a Marangoni effect. Subsequently, this film undergoes a dewetting instability. However, the final equilibrium is not partial wetting. The film breaks up into droplets with a mesoscopic (approximately 50 A) film in between. These observations result from a subtle interplay between short- and long-range forces: surfactants naturally present in the lipids favor wetting, while the van der Waals forces oppose it. In addition, this reveals the likely organization of the hydrolipid film that covers and protects the skin.
Lipid compsition on comedones compared with that of human skin surface in acne patients.
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Sebaceous gland response in man to prolonged total caloric deprivation.
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Characterization of wax esters, triglycerides, and free fatty acids of follicular casts.
The abnormal impactation of a sebaceous follicle (the follicular cast) has been implicated as the preclinical lesion of acne vulgaris. We have characterized the lipid composition of these structures in the first of a series of studies aimed at the identification of sebaceous lipids that may be associated and/or responsible for the initiation of clinical lesions. The lipid composition of follicular casts was analyzed using thin-layer chromatography, gas chromatography, and mass spectrometry. The mean wet weight of the casts was 24.7 +/- 8.6 micrograms and 7.2 +/- 5.6 micrograms (29.4 +/- 13.5%) was lipid. Cholesterol (3.8 +/- 1.8%) and cholesterol esters (2.0 +/- 2.7%), wax esters (25.3 +/- 6.0%), squalene (19.9 +/- 6.6%), triglycerides (16.1 +/- 7.8%), and free fatty acids (33.0 +/- 10.0%) were all present in cast lipid. Fatty acids of the free fatty acid and triglyceride fraction ranged from C12 to C22. The major components of the free fatty acids were C14:0, C15:0, C16:1, C16:0, 2-me-C17:0, and C18:1. In the triglyceride fraction C14:0, C15:0, C16:0, C18:1, and C18:0 dominated. The free fatty acids were composed of normal saturated (50.6%), normal unsaturated (32.8%), and monomethyl branched (16.6%) acids; the triglyceride fraction contained (86.3%) normal saturated (10.8%), normal unsaturated, and (3.0%) monomethyl branched fatty acids. Wax esters of follicular casts included esters ranging from C26:1 to C38:0. Saturated esters predominated and both odd- and even-numbered esters were present. The most abundant fatty acid moieties of these esters were C16:0 and C15:0, whereas C14:0, C17:0, and C20:0 were the most frequently detected alcohol moieties.
Anatomical variation in the amount and composition of human skin surface lipid.
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The role of the aerobic microflora in the genesis of fatty acids in human surface lipids.
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Localization of epidermal growth factor immunoreactivity in sheep skin during wool follicle development.
Interactions among the cells and matrices of the epidermis and mesenchyme of skin are essential for hair follicle initiation and development. The identification of receptors for epidermal growth factor (EGF) on epithelial components of the follicle during growth has suggested that the ligand participates in some of these events. We have used affinity-purified antibodies together with an alkaline phosphatase detection procedure to investigate the distribution of EGF in the skin of the sheep during wool follicle formation. Immunoreactivity was restricted to the periderm and intermediate layers of fetal epidermis at 55 d of gestation, when the first wave of wool follicles are initiated. This particular distribution persisted during subsequent development but never became associated with the basal cells of the epidermis. The activity was lost around 118 d, coinciding with sloughing of the periderm. No immunoreactivity was found in the plugs or the dermal condensations of the developing follicles. At approximately 105 d of gestation, however, reactions were detected in the outer root sheath as the follicles matured and in the differentiating cells of the sebaceous glands. A similar distribution pattern was also noted at 140 d, just prior to birth, and in adult animals, indicating that EGF was sequestered and perhaps synthesized within the follicle. The presence of immunoreactive material was also associated with the pilary canals and the skin surface, suggesting that this may have had its origin in the sebaceous glands. We examined this using a radioreceptor assay for EGF. Material washed from the skin surface and sebaceous gland extracts were found to displace 125I-EGF from rat liver membranes, in parallel with mouse EGF.
The inability of a bacterial lipase inhibitor to control acne vulgaris.
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An in vivo evaluation of the inflammatory effect of purified comedonal components in human skin.
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Measurement of the time between synthesis and surface excretion of sebaceous lipids in sheep and man.
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Esterification of (4--14C)cholesterol by cutaneous bacteria (Staphylococcus epidermidis, Propionibacterium acnes, and Propionibacterium granulosum).
Cholesterol and cholesteryl esters constitute 3 to 5% of the lipids derived from human sebaceous glands. The present study demonstrates that cutaneous bacteria, Staphylococcus epidermidis, and to a lesser extent Propionibacterium acnes, and Propionibacterium granulosum, esterify [4--14C]cholesterol to steryl esters in vitro. The degree of esterification is a characteristic of the strain of organism, ranging from 0 to 32.7% in the organisms tested. Cholesterol esterification in these experiments was dependent on the addition of homogenates of isolated, pooled sebaceous glands to the incubation medium. Indirect evidence suggests that the fatty acids from sebaceous triglycerides are utilized for cholesterol esterification by the bacteria. These results indicate that the proportion of steryl esters in skin surface lipids may be influenced by the density of the microbial population in the skin.