Alessia Quatela1, Lynda Miloudi, Ali Tfayli, Arlette Baillet-Guffroy. 1. Laboratory of Lipids: Analytical and Biological Systems Lip(Sys)2, Group of Analytical Chemistry of Paris-Sud (GCAPS), University Paris Sud, Universitx00E9; Paris-Saclay, Chx00E2;tenay-Malabry, France.
Abstract
BACKGROUND: In vivo Raman spectroscopy is a powerful tool for real-time analysis and in situ evaluation of tissues such as the skin. The efficiency of this technique has been widely demonstrated as a label-free method for in vivo evaluation of the skin. The aim of this study is to gather information about inter- and intra-individual variations in the spectral descriptors of water content and structure, organization of the lipid barrier and structure of proteins in the stratum corneum (SC). METHODS: In vivo SC measurements were performed on 17 female volunteers aged 20-30 years (phototypes I and II). For intra-individual variability, spectral collection was performed on 5 successive days per volunteer. Shapiro-Wilk and Cochran tests were applied to check the normality and the homoscedasticity of variances. ANOVA was then applied to evaluate intra- and intergroup variability. RESULTS: ANOVA was performed on the spectral descriptors of water content and structure, organization of the lipid barrier and secondary structure of proteins in the SC. No significant intra- and interday variability was observed for all volunteers. Despite the low value of the total relative standard deviation, a highly significant variation was observed between volunteers. CONCLUSION: Interindividual variability for Raman measurements is significant for a set of volunteers with normal nondiseased SC and close phototypes. This variability should be taken into consideration as a threshold for significant variance when working in vivo.
BACKGROUND: In vivo Raman spectroscopy is a powerful tool for real-time analysis and in situ evaluation of tissues such as the skin. The efficiency of this technique has been widely demonstrated as a label-free method for in vivo evaluation of the skin. The aim of this study is to gather information about inter- and intra-individual variations in the spectral descriptors of water content and structure, organization of the lipid barrier and structure of proteins in the stratum corneum (SC). METHODS: In vivo SC measurements were performed on 17 female volunteers aged 20-30 years (phototypes I and II). For intra-individual variability, spectral collection was performed on 5 successive days per volunteer. Shapiro-Wilk and Cochran tests were applied to check the normality and the homoscedasticity of variances. ANOVA was then applied to evaluate intra- and intergroup variability. RESULTS: ANOVA was performed on the spectral descriptors of water content and structure, organization of the lipid barrier and secondary structure of proteins in the SC. No significant intra- and interday variability was observed for all volunteers. Despite the low value of the total relative standard deviation, a highly significant variation was observed between volunteers. CONCLUSION: Interindividual variability for Raman measurements is significant for a set of volunteers with normal nondiseased SC and close phototypes. This variability should be taken into consideration as a threshold for significant variance when working in vivo.
Authors: Stephan Bielfeldt; Sabrina Laing; Tomasz Sadowski; Hemali Gunt; Klaus-Peter Wilhelm Journal: Skin Res Technol Date: 2019-12-09 Impact factor: 2.365