Morphological, structural and biophysical properties of French and Brazilian photoaged skin.

BACKGROUND: Knowledge of skin biology and its alterations in different populations is very important for the development of appropriate skincare strategies. OBJECTIVES: To evaluate and compare morphological, structural and biophysical properties of photoaged skin in French and Brazilian populations, using biophysical and skin-imaging techniques. METHODS: Forty-one French and 41 Brazilian healthy, female volunteers aged between 40 and 65 years were enrolled. Each participant completed a questionnaire concerning habits related to cosmetic use, sun exposure and sun protection during different life periods. Skin on the face and volar forearm was evaluated using noninvasive techniques, to determine skin colour, transepidermal water loss (TEWL), stratum corneum water content, skin microrelief, skin viscoelasticity and dermis structure. Reflectance confocal microscopy was used to measure epidermal layer thickness and epidermal morphological and structural characteristics. RESULTS: Compared with Brazilian skin, French skin was more hydrated, had a lower TEWL and presented a distinct viscoelastic profile on the forearms and face. Brazilian facial skin was more wrinkled, and the dermis was less echogenic on the forearms and face. The French participants had thicker stratum corneum. Brazilian facial skin presented a higher prevalence of rete ridge effacement, low interkeratinocyte reflectance, huddled collagen and solar elastosis. CONCLUSIONS: Morphological, structural and biophysical differences were found when assessing the skin of the Brazilian and French participants, who were exposed to different environmental factors.

Elastic wave induced by friction as a signature of human skin ageing and gender effect.

BACKGROUND: In this work, we propose an innovative approach based on a rotary tribometer coupled with laser velocimetry for measuring the elastic wave propagation on the skin. METHODS: The method is based on a dynamic contact with the control of the normal force (Fn ), the contact length and speed. During the test a quantification of the friction force is produced. The elastic wave generated by friction is measured at the surface of the skin 35 mm from the source of friction exciter. In order to quantify the spectral range and the energy property of the wave generated, we have used laser velocimetry whose spot laser diameter is 120 µm, which samples the elastic wave propagation at a frequency which may reach 100 kHz. In this configuration, the speaker is the friction exciter and the listener the laser velocimetry. In order to perform non-invasive friction tests, the normal stress has been set to 0.3 N and the rotary velocity to 3 revolutions per second, which involves a sliding velocity of 63 mm/s. RESULTS AND CONCLUSIONS: This newly developed innovative tribometer has been used for the analysis of the elastic wave propagation induced by friction on human skin during chronological ageing and gender effect. Measurements in vivo have been made on 60 healthy men and women volunteers, aged from 25 to 70. The results concerning the energy of the elastic wave signature induced by friction show a clear difference between the younger and older groups in the range of a low band of frequencies (0-200 Hz). The gender effect was marked by a 20% decrease in the energy of elastic wave propagation in the female group.

Influence of skin ageing features on Chinese women's perception of facial age and attractiveness.

OBJECTIVES: Ageing leads to characteristic changes in the appearance of facial skin. Among these changes, we can distinguish the skin topographic cues (skin sagging and wrinkles), the dark spots and the dark circles around the eyes. Although skin changes are similar in Caucasian and Chinese faces, the age of occurrence and the severity of age-related features differ between the two populations. Little is known about how the ageing of skin influences the perception of female faces in Chinese women. The aim of this study is to evaluate the contribution of the different age-related skin features to the perception of age and attractiveness in Chinese women. METHODS: Facial images of Caucasian women and Chinese women in their 60s were manipulated separately to reduce the following skin features: (i) skin sagging and wrinkles, (ii) dark spots and (iii) dark circles. Finally, all signs were reduced simultaneously (iv). Female Chinese participants were asked to estimate the age difference between the modified and original images and evaluate the attractiveness of modified and original faces. RESULTS: Chinese women perceived the Chinese faces as younger after the manipulation of dark spots than after the reduction in wrinkles/sagging, whereas they perceived the Caucasian faces as the youngest after the manipulation of wrinkles/sagging. Interestingly, Chinese women evaluated faces with reduced dark spots as being the most attractive whatever the origin of the face. The manipulation of dark circles contributed to making Caucasian and Chinese faces being perceived younger and more attractive than the original faces, although the effect was less pronounced than for the two other types of manipulation. CONCLUSION: This is the first study to have examined the influence of various age-related skin features on the facial age and attractiveness perception of Chinese women. The results highlight different contributions of dark spots, sagging/wrinkles and dark circles to their perception of Chinese and Caucasian faces.

Self-reported skin sensitivity in a general adult population in France: data of the SU.VI.MAX cohort.

OBJECTIVE: This study aimed to examine the frequency of self-assessed facial skin sensitivity and its different patterns, and the relationship with gender and sun sensitivity in a general adult population. METHODS: A standardized 11-item questionnaire investigating reactions experienced during the past year was developed. The questions explored different patterns of skin sensitivity: pattern I (blushing related to vascular reactivity), pattern II (skin reactions to certain environmental conditions), pattern III (skin reactions after substance contact), and for women pattern IV ('breakout of spots' related to menstrual cycle). Additional items were addressed for women and men, including sun sensitivity. The questionnaire was administered to a large middle-aged population involved in the 'Supplément en Vitamines et Minéraux Antioxydants' (SU.VI.MAX) cohort. RESULTS: Sensitive facial skin was reported by 61% of the women (n = 5074) and 32% of the men (n = 3448), and the frequency decreased with age. The frequency of patterns I, II and III was greater for women (78, 72 and 58%, respectively) than for men (56, 48 and 28%) of comparable classes of age. The frequency of pattern IV was reported by 49% of premenopausal women, and skin reactions after shaving by 41% of the men. Sun sensitivity was found to be a major component of skin sensitivity. Factor analysis showed that individuals with fair phototype frequently evoked reactions associated with pattern I, and skin redness and burning sensations were related to certain environmental conditions (pattern II). CONCLUSION: Skin sensitivity is a common concern that declines with age and is relevant for men as well as for women.

[Effect of hormonal replacement therapy on cutaneous biophysical properties of menopausal women]. / Effet de traitements hormonaux de substitution sur des propriétés biophysiques de la peau de femmes ménopausées.

PURPOSE: The aim of this analysis was to study the possible effect of hormonal replacement therapy on some biophysical properties of the skin of menopausal women. SUBJECTS AND METHODS: A study was carried out on 106 menopausal, phototype I to IV women with clinically healthy skin. During the medical evaluation, the menopausal status, duration of the menopause, and, possible use of hormone replacement therapy and its duration were collected. A series of biophysical skin parameters in controlled environmental conditions was assessed on the face: sebum casual level, skin surface pH, skin colour, transepidermal water loss, capacitance, conductance, skin relief and temperature. The same parameters except for sebum were assessed on the forearm. Three sub-samples were defined according to the duration of the menopause and of hormone replacement therapy. RESULTS: The skin colour parameters revealed a greater red intensity value in menopausal women who had been treated for at least one year. In menopausal women who had been treated for at least 5 or 10 years, the biophysical measurements were significantly higher for the parameters evaluating hydration and sebum secretion, associated with higher values for the yellow intensity parameter and the skin relief parameters on the forehead. CONCLUSION: These results support the subjective impression and the clinical evaluation according to which hormonal replacement therapy could modify the development and the severity of some properties associated with skin ageing after the onset of menopause.

Assessment of sun reactive skin type with multiple correspondence analysis, hierarchical and tree-structured classification methods.

The sun reactive skin type classification is based on sunburn susceptibility, tanning ability and phenotypic information. As subjects rarely match all features of a given skin type, the attribution to a class is partially subjective. The aims of the study, were to analyse the contribution of each characteristic to the classification made by the expert, and to establish a classification based on a statistical approach conducted on 212 women living in the Ile-de-France area. Multiple regression was used to construct a formula for each phototype. The coefficients obtained demonstrated that the importance of each characteristic was extremely variable from one phototype to another, suggesting that the phototype determination could be facilitated by adding a weight for every characteristic in the decision. Then, multiple correspondence analysis and clustering analysis methods showed that one phototype could be divided into two more homogenous classes.

Analysis of circadian and ultradian rhythms of skin surface properties of face and forearm of healthy women.

Biologic rhythms of cells and organisms are well documented and have been extensively studied at the physiologic and molecular levels. For the skin, many circadian changes have been investigated but few systematic studies comparing skin at different body sites have been reported. In this study we investigated facial and forearm skin circadian rhythms in eight healthy Caucasian women. Noninvasive methods were used to assess skin capacitance, sebum excretion, skin temperature, transepidermal water loss, and skin surface pH on fixed sites of the face and the volar forearm during a 48 h span under standardized environmental conditions. Using the cosinor or ANOVA methods, circadian rhythms could be detected for sebum excretion (face), transepidermal water loss (face and forearm), skin temperature (forearm), pH (face), and capacitance (forearm). No circadian rhythmicity was found for the other biophysical parameters. In addition to the 24 h rhythm component, rhythms with periods of 8 h were found for sebum excretion, of 8 and 12 h for transepidermal water loss (face and forearm), and of 12 h for skin temperature (forearm). Our study confirms that rhythms of skin surface parameters are readily measurable and that these rhythms differ between different sites. Furthermore, we demonstrate for the first time that, for transepidermal water loss (face and forearm), sebum excretion, and skin temperature (forearm), in addition to circadian rhythms, ultradian and/or component rhythms can be detected.