The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Jens J. Thiele - One of the best experts on this subject based on the ideXlab platform.
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Ultraviolet a induces generation of squalene monohydroperoxide isomers in human sebum and skin Surface Lipids in vitro and in vivo.
The Journal of investigative dermatology, 2003Co-Authors: Swarna Ekanayake Mudiyanselage, Matthias Hamburger, Peter Elsner, Jens J. ThieleAbstract: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.
B. Williamson - One of the best experts on this subject based on the ideXlab platform.
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Variations in skin Surface Lipid composition with different sampling techniques. I.
The British journal of dermatology, 2006Co-Authors: William J. Cunliffe, J. A. Cotterill, B. WilliamsonAbstract:SUMMARY.— The effect of 3 different sampling techniques on forehead Surface Lipid biochemistry was investigated. Samples obtained by either a sponge method or by ether washings contained significantly more free fatty acid and cholesterol and less triglyceride, wax ester and squalene than did samples collected by absorbent papers. The reasons for these differences are discussed and it is suggested that more careful attention to detail is necessary in the sampling and handling of Surface Lipids before biochemical analysis.
Ali Tfayli - One of the best experts on this subject based on the ideXlab platform.
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Skin Surface Lipid composition in women: increased 2,3-oxidosqualene correlates with older age
European Journal of Dermatology, 2020Co-Authors: Aline Rigal, Rime Michael-jubeli, Armelle Bigouret, Alex Nkengne, Dominique Bertrand, Arlette Baillet-guffroy, Ali TfayliAbstract:Background The importance of the hydroLipidic film of skin has been well documented, however, few data are available in cases of very old age. Objectives Our aim was to characterize the difference in skin Surface Lipid (SSL) composition between individuals of different age groups. Materials and Methods Data were collected from the forehead of 22 young volunteers (18–24 years old) and 18 senior volunteers (70–75 years old). The amount of sebum was obtained by sebumetry. To acquire relevant information about the molecular composition of high complex mixtures, SSLs were analysed in a single run to ensure that the Lipid structures remain intact, using high-temperature gas chromatography coupled with mass spectrometry. The major features associated with aged skin were documented. Result In aged skin, a lower sebum content was observed, together with modification of the relative SSL composition involving a significant reduction in the intensity of many components of the hydroLipidic film. In contrast, the intensity of 2,3-oxidosqualene was shown to increase with an inverse relationship between triglycerides and their hydrolytic products. Conclusion These adaptations could be related to modifications of enzymatic activity.
F C Powell - One of the best experts on this subject based on the ideXlab platform.
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the fatty acid profile of the skin Surface Lipid layer in papulopustular rosacea
British Journal of Dermatology, 2012Co-Authors: Ni S Raghallaigh, Katrin Bender, N Lacey, Lorraine Brennan, F C PowellAbstract:Summary Background Patients with papulopustular rosacea (PPR) frequently complain of dry, sensitive skin. We have previously demonstrated that patients with PPR have reduced skin Surface hydration levels in the presence of normal sebum casual levels, suggesting that it may be the quality and not the quantity of sebum that plays a role in PPR. Objectives To compare the sebaceous fatty acid composition of patients with PPR to that of controls with normal facial skin. Methods The sebaceous fatty acid composition of 25 patients with PPR and 24 age- and sex-matched controls was analysed by gas chromatography - mass spectrometry. Results Myristic acid (C14:0) was present in greater concentrations in PPR sebum, while the long chain saturated fatty acids arachidic acid (C20:0), behenic acid (C22:0), tricosanoic acid (C23:0) and lignoceric acid (C24:0) as well as the monounsaturated fatty acid cis-11-eicosanoic acid (C20:1) were present in the sebum of patients with PPR in lesser concentrations as compared with controls. Conclusions There is increasing evidence that sebaceous fatty acids play a role in the maintenance of skin barrier integrity. We have shown for the first time that patients with PPR have an abnormal sebaceous fatty acid composition, with reduced levels of long chain saturated fatty acids. These new findings may have therapeutic implications for the development of sebum-modifying nonantibiotic treatments for patients with PPR.
Swarna Ekanayake Mudiyanselage - One of the best experts on this subject based on the ideXlab platform.
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Ultraviolet a induces generation of squalene monohydroperoxide isomers in human sebum and skin Surface Lipids in vitro and in vivo.
The Journal of investigative dermatology, 2003Co-Authors: Swarna Ekanayake Mudiyanselage, Matthias Hamburger, Peter Elsner, Jens J. ThieleAbstract: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.