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Testing the Discriminative Capacity of Compartmental Modeling for the Analysis of the In-Vivo Epidermal Water Content Changes Following Topical Application under Occlusion / Pedro Contreiras Pinto in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 87-92 Titre : Testing the Discriminative Capacity of Compartmental Modeling for the Analysis of the In-Vivo Epidermal Water Content Changes Following Topical Application under Occlusion Type de document : texte imprimé Auteurs : Pedro Contreiras Pinto, Auteur ; Luis Marcelo Pereira, Auteur ; Rui Minhos, Auteur ; Luis Monteiro Rodrigues, Auteur Année de publication : 2002 Article en page(s) : p. 87-92 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Skin  hydration'  'efficacy  testing'  'mthematical  modeling'  POST  'in-vivo  measurement'  evaporation  'dynamic  water  loss'  TEWL Index. décimale : 668.5 Parfums et cosmétiques Résumé : Mathematical modeling of cutaneous variables is an attratictive strategy to meet the compex nature of in-vivo skin, especially in the presence of an external stimulus such as a topical product. Despite the oversimplification implied, meeting the conceptualization of the model with the representative (physiological) variables is still a major difficulty, often impairing the model validity. Once achieved, however, its applicability will mostly depend on the demonstration of the accuracy and practicability of the model. In previous works, the authors developed a bi-compartmental model designed to dynamically describe the Trans-epidermal water loss(TEWL) curves obtained in-vivo from the Plastic Occlusion Stress Test (POST) methodology. Occlusion was performed in healthy human volunteers (n=10) occluded with either 10% glycerin in water solution or water alone. Desorption curves allowed to obtain kinetic parameters such as k(evap)(the water evaporation rate at skin surface), t1/2 evap(the evaporation half-life), and DWM (the dynamic water mass) allowing a detailed quantitative description of the hydration process. Results demonstrate that the proposed model is adequate to identify significant differences (p<0.05) between the curve profiles, revealing the different hydration mechanisms involved, and suggesting an interesting application potential for the substantiation and efficacy testing of cosmectics. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10649 [article]

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New Technique to Capture Viscoelastic Changes in Hair Induced by Mechanical Stress / S. B. Hornby in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 93-97 Titre : New Technique to Capture Viscoelastic Changes in Hair Induced by Mechanical Stress Type de document : texte imprimé Auteurs : S. B. Hornby, Auteur ; Nigel J. P Winsey, Auteur ; Stephen P. Bucknell, Auteur Année de publication : 2002 Article en page(s) : p. 93-97 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Cyclic  testing'  Fatigue  'Elastic  modulus'  Resiliency  'Tensile  stress'  'Hair  breakage' Index. décimale : 668.5 Parfums et cosmétiques Résumé : In a previous article [1], we have described the mechanical fatigue behaviour of hair fibers subjected to intermitted tensile deformations using the Cyclic Tester (Dia-Stron, Ltd., Andover, UK) in order to mimic stresses encountered during grooming procedures. The instrument imparts repeated tensile load cycles to the hair and records the numbers of cycles at the break point of each hair fiber. The distributions of the number of cycles required to cause hair fiber breakage were analyzed using the Weibull distribution and the beneficial effect of certain conditioners was discussed. The Cyclic Tester is also capable of recording load-elongation data for the hair fiber during the load cycles. In this study, we captured the load elongation data at selected load cycles of very damaged tip ends of single hair fibers and compared this data to that obtained for the undamaged root end of the same fiber using the Cyclic Tester. The changes in the hair fiber elastic and viscoelastic characteristics of very damaged and unaltered hair as a function of a number of prior deformations were compared. The instrument was enable to give a portrait of the viscoelastic changes in hair during repetitive stress. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10651 [article]

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Emollients and Emulsifiers Exert their Sensory Impact in Different Phases of the Sensory Evaluation Process but How Does One Demonstrate the Absence of such an Influence? / Johann W. Wiechers in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 99-105 Titre : Emollients and Emulsifiers Exert their Sensory Impact in Different Phases of the Sensory Evaluation Process but How Does One Demonstrate the Absence of such an Influence? Type de document : texte imprimé Auteurs : Johann W. Wiechers, Auteur ; Marie-Claire Taelman, Auteur ; Vincent A. L. Wortel, Auteur ; Cock Verboom, Auteur ; J. Chris Dederen, Auteur Année de publication : 2002 Article en page(s) : p. 99-105 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Skin  sensory  research'  Emulsifier  'Cosmetic  ingredient'  Formulations  'Principal  component  analysis' Index. décimale : 668.5 Parfums et cosmétiques Résumé : Whereas most experimental procedures in science are typically geared to show the presence or existence of objects or phenomena, showing the lack of presence, i.e. absence, of something is a lot more complicated, in particular if it cannot be seen. In order to demonstrate that a new emulsifier system did not impact the skin feel of a formulation in which it was incorporated, various formulations only differing in the emulsifier were made and their skin feel was compared using descriptive analysis. Paired comparisons were used to maximize the chance of measuring a difference. Clear differences were detected between the formulations in the early phases of the sensory evaluation process, demonstrating that emulsifiers in general do contribute to skin feel and to different degrees. The only remaining question was "what is no influence?" Therefore, the formulations were compared with the neat oils, but the differences were found to be dramatic for all comparisons. When comparing formulations that only differed in their emollients, it could be shown that the formulations containing the new emulsifier were able to maintain small differences in skin feel that were also obsrved for the neat oils whereas the other emulsifier systems failed to maintain these differences or introduced new ones. The results also clearly demonstreted that while emulsifiers affect the skin feel in the early phases of sensory evaluation (appearance, pick-up and run-out), emollients exert their sensory impact predominantly during the after-feel of a cosmetic formulation. It was conclued that despite the practical experience that the new emulsifier did not contribute to skin feel, it is impossible to show this due to the lack of a true reference that represents no skin effect. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10652 [article]

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A Mixture of Magnesium and Calcium Salts Accelerates Skin Barrier Recovery and Improves Surfactant-Induced Dry Skin / M. Denda in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 107-110 Titre : A Mixture of Magnesium and Calcium Salts Accelerates Skin Barrier Recovery and Improves Surfactant-Induced Dry Skin Type de document : texte imprimé Auteurs : M. Denda, Auteur ; Izumi Horii, Auteur ; Tasuku Takamatsu, Auteur Année de publication : 2002 Article en page(s) : p. 107-110 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Stratum  corneum'  Epidermis  Keratinocyte  'PH'  Potassium  Sodium Index. décimale : 668.5 Parfums et cosmétiques Résumé : Ions such as magnesium and calcium play an important role in various biological functions. In the present study, we first visualized the distribution of calcium, potassium, sodium, and hydrogen ions in the human epidermis and examined the effects of skin barrier disruption. In normal skin, both calcium and magnesium were localized at a high concentration in the epidermal granular layer. The hydrogen ion was also high in the upper epidermis. Sodium did not show any obvious gradient over the epidermis. The potassium concentration was the lowest in the upper epidermis. After barrier disruption by tape stripping, the gradients of calcium, magnesium, ant potassium disapeared while the pH gradient was not altered. Topical application of an aqueous solution of magnesium chloride accelerated the barrier recovery after tape stripping. Topical application of magnesium chloride and calcium chloride was found to hasten the barrier recovery more effectively than a solution of magnesium chloride. The mixture of magnesium and calcium chloride improve the conditions for dry, scaly skin induced by sodium dodecyl sulfate. These results suggest that both magnesium and calcium play an important role in the skin barrier homeostasis and that these ions are effective in improving skin condition. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10653 [article]

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Design and optimization of antiperspirant formulations using the artificial neural networks and genetic algorithms / Kader Comlekci in IFSCC MAGAZINE, Vol. 5, N° 2 (04-05-06/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 2 (04-05-06/2002) . - p. 114-117 Titre : Design and optimization of antiperspirant formulations using the artificial neural networks and genetic algorithms Type de document : texte imprimé Auteurs : Kader Comlekci, Auteur ; M. Turkoglu, Auteur Année de publication : 2002 Article en page(s) : p. 114-117 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Antiperspirant  'Artificial  neural  networks'  'Genetic  algorithms'  'Mathematical  modeling' Index. décimale : 668.5 Parfums et cosmétiques Résumé : In this study, the effects of concentrations of stearyl alcohol (10, 20 and 30%), hydrogenated castor oil (1, 3 and 5%) and talc (1, 3 and 5%) on the properties of antiperspirant sticks were investigated. Thirty-one batches resulted from the experimental design. The artificial neural network methodology (ANN), genetic algorithms (GA) were used for data analysis and optimization. Breaking force and spreadability were measured as the responses. ANN and genetic models provided R2 values between 0.6474 and 0.9984 for the measured responses. When a set of validation experiments was analyzed, GA predictions of antiperspirant characteristics were much better than the ANN predictions. Optimization based on GA showed that using stearyl alcohol at 18 - 22% with talc at 2 - 4% and hudrogenated castor oil at 4 - 5% would produce the antiperspirant stick that leaves the least residue and is easy to apply, but not so easily broken. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10655 [article]

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