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At least 1,153 records · Page 64Linked to original sources
PubMed1999

Production and oxidation of wool grease after shearing.

OBJECTIVE: To measure the production and amount of oxidation of wool grease secreted immediately after shearing. To identify components of wool grease that might act as a carrier to facilitate lateral diffusion of topically applied insecticides. DESIGN: Fine-wool Merino sheep were shorn and residual greasy wool was collected from the sheep's flank. The quantity of grease produced, and the amount of oxidation was measured during 18 days after shearing. Wool grease was fractionated into five component groups based on their polarity and the degree of oxidation in these fractions determined. RESULTS: There was a 24% increase in grease production within 2 days after shearing but secretions returned to pre-shearing amounts after 4 days. During this period wool grease oxidized rapidly. Of the grease fractions examined, sterol and wax esters remained essentially unoxidized whereas free sterols such as cholesterol and lanosterol, fatty acids and polar lipids, aldehydes and alcohols were extensively oxidized within 7 days after shearing. CONCLUSION: The transient increase in grease production after shearing may facilitate diffusion of topically applied synthetic pyrethroid insecticides. Oxidation of grease components may then contain the insecticide and limit further diffusion. Incorporating the insecticide in non-oxidising fractions of wool grease may make insecticide dispersion more efficient.

Administration, Cutaneous↗
PubMed1974

Skin lipids: their biochemical uniqueness.

Two key words characterize the uniqueness of skin lipids: complexity and perversity. Each suggests a function. Complexity manifests itself in the large number and variety of both saturated and unsaturated fatty chains synthesized by human skin. Functionally, this allows each individual to have a distinct odor or chemical fingerprint. Perversity manifests itself when one compares the lipids synthesized by skin with those synthesized by internal tissues. For example, skin makes odd instead of only even chains, branched instead of only straight chains, free instead of only esterified acids, places double bonds in unusual positions in the fatty chains, extends chains to extreme lengths, and accumulates intermediates in the synthesis of a biologically valuable compound such as cholesterol. Functionally, these products may pose metabolic problems to potential pathogens and thus contribute to the survival of only compatible microorganisms.

Chemical Phenomena↗
PubMed1973

Acne vulgaris.

Explore the source record for details and available documents.

Acne Vulgaris↗
PubMed1998

The pilosebaceous unit is part of the skin immune system.

It is well established that the functional state of sebaceous glands in vivo is a tightly regulated process orchestrated through the interaction of male sex hormones and functional androgen receptors expressed on sebocytes. In the last few years, however, it has become increasingly apparent that sebocytes like epidermal keratinocytes express a variety of cytokines which are implicated in inflammatory and immune responses. For example, sebocytes in vivo have been found to highly express tumor necrosis factor alpha (TNF-alpha) as determined by immunohistochemical and electron-microscopic methods. Moreover, certain neuropeptides including vascular intestinal peptide and proopiomelanocortin (POMC) peptides as well as their receptors have been localized within the pilosebaceous unit of murine and human skin. Since POMC peptides such as alpha-melanocyte-stimulating hormone have recently been shown to exert important immunoregulatory effects by antagonizing the function of proinflammatory cytokines (e.g interleukin 1, interleukin 6 and TNF-alpha), induction of immunosuppressive cytokines (like interleukin 10), modulation of costimulatory molecule expression (e.g. B7-2) or suppression of macrophage-derived nitric oxide, complex interactions between these mediators and their target cells within the pilosebaceous gland seem to exist. The successful cultivation of sebocytes will provide a model by which the effect of these mediators can be studied in detail in order to shed light onto the various pathophysiological conditions of sebaceous glands.

Animals↗
PubMed2001

The antioxidant network of the stratum corneum.

Many studies have demonstrated beneficial health effects of topical antioxidant application; however, the underlying mechanisms are not well understood. To better understand the protective mechanism of oxogenous anti-oxidants, it is important to clarify the physiological distribution, activity and regulation of antioxidants. Also, the generation of ROS by the resident and transient microbial flora and their interaction with cutaneous antioxidants appears to be of relevance for the redox properties of skin. Our studies have demonstrated that alpha-tocopherol is, relative to the respective levels in the epidermis, the major antioxidant in the human SC, that alpha-tocopherol depletion is a very early and sensitive biomarker of environmentally induced oxidation and that a physiological mechanism exists to transport alpha-tocopherol to the skin surface via sebaceous gland secretion. Furthermore, there is conclusive evidence that the introduction of carbonyl groups into human SC keratins is inducible by oxidants and that the levels of protein oxidation increase towards outer SC layers. The demonstration of specific redox gradients within the human SC may contribute to a better understanding of the complex biochemical processes of keratinization and desquamation. Taken together, the presented data suggest that, under conditions of environmentally challenged skin or during prooxidative dermatological treatment, topical and/or systemic application of antioxidants could support physiological mechanisms to maintain or restore a healthy skin barrier. Growing experimental evidence should lead to the development of more powerful pharmaceutical and cosmetic strategies involving antioxidant formulations to prevent UV-induced carcinogenesis and photoaging as well as to modulate desquamatory skin disorders.

Aging↗
PubMed2003

Update and future of hormonal therapy in acne.

Hormonal therapy is an important component in the treatment of women with acne who may or may not have elevated serum androgens. The mainstays of hormonal therapy include oral contraceptives and antiandrogens such as cyproterone acetate, flutamide or spironolactone. Recent research over the past several years has unraveled some of the details regarding the way that the skin and sebaceous glands synthesize and metabolize hormones. The knowledge gained from this work may provide an impetus for future drug discovery in the hormonal treatment of acne and lead to improvements in the care of our patients with acne.

Acne Vulgaris↗
PubMedDate not supplied

Vitamin E delivery to human skin by a rinse-off product: penetration of alpha-tocopherol versus wash-out effects of skin surface lipids.

alpha-Tocopherol, the major biologically active form of vitamin E, represents a frequently added lipophilic compound of skin care products. Despite its emerging use in rinse-off formulations, little is known on its efficacy with respect to its deposition or its antioxidant potential in human skin. The objective of this study was to investigate whether the single use of an alpha-tocopherol-enriched rinse-off product provides effective deposition of alpha-tocopherol on human stratum corneum. To test this, forearm skin of 13 volunteers was washed either with an alpha-tocopherol-enriched rinse-off product (test product, TP) or with an alpha-tocopherol-free vehicle control (control product, CP) (contralateral arm) using a standardized wash protocol. Thereafter, skin surface lipids were extracted with pure ethanol after the wash procedure as well as after 24 h. Additionally, one group of volunteers was subjected to irradiation of their forearms with low-dose UVA (8 J/cm(2)) prior to lipid extraction. Skin lipid extracts were analyzed by high performance liquid chromatography using electrochemical detection for vitamin E and UV detection for squalene (SQ) and squalene monohydroperoxide. The results of this in vivo study demonstrated that (1) while CP treatment lowers, TP treatment strongly increases alpha-tocopherol levels of skin barrier lipids; (2) increased vitamin E deposition levels were maintained for a period of at least 24 h, and (3) TP treatment significantly inhibited photooxidation of SQ. In conclusion, the use of alpha-tocopherol-enriched rinse-off products may help to maintain the integrity of the skin barrier by providing protection against photooxidative stress at the level of skin surface lipids.

Administration, Cutaneous↗
PubMed2006

Hair follicles - a long-term reservoir for drug delivery.

Nanoparticles represent an important drug carrier system. Recently, we have reported on the penetration and storage behavior of particular and non-particular substances revealing the superiority of particular substances in the range of 300-400 nm. In this regard, it was assumed that the rigid hair shaft acts as a geared pump, moving the particles deeper into the hair follicle. In the present investigation, the storage reservoir capacity of the stratum corneum and the hair follicle infundibulum and canal are compared. Interestingly, we could demonstrate a 10 times longer storage within the hair follicles. These results underscore the importance of the hair follicle for drug delivery purposes, mainly highlighting new possibilities for the future concerning retarded delivery, application frequency, and galenic design.

Administration, Topical↗
PubMed1996

Oral 9-cis-retinoic acid versus 13-cis-retinoic acid in acne therapy.

BACKGROUND: 9-cis-Retinoic acid (9-cis-RA) is as active as 13-cis-retinoic acid (13-cis-RA) in inhibiting the proliferation of cultured human sebocytes and in reducing the size of sebaceous glands of hamsters. OBJECTIVE: Evaluate the anti-acne effect of 9-cis-RA compared to that of 13-cis-RA in a pilot study. METHODS: Four young male patients with acne were treated in an open study consecutively with 9-cis-RA and 13-cis-RA given at similar doses. RESULTS: No beneficial effects were observed with 9-cis-RA in any of the patients whereas all responded favorably to 13-cis-RA. CONCLUSION: For the two retinoids tested, the anti-acne effect correlates with the sebosuppressive effect in humans.

Acne Vulgaris↗