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.     

Progressive evaluation of skin irritancy of cosmetics using human volunteers

Cosmetics and toiletries should not elicit adverse reactions in use. Neither should they cause unacceptable effects if mis-used. Reliable prediction of these product attributes can be achieved by subjecting human volunteers to typical product exposure and to grossly exaggerated exposure. However, to ensure that volunteers do not sustain harmful effects there needs to be a cautiously progressive programme of testing.
There must be adequate data on record to support exposure of human skin to the test material. The first contact with human skin should be in a small area, for short duration, and be very closely observed. When the effects are well within acceptable limits the exposure can be extended. As information accumulates, the application procedure can evolve towards simulation of the intended use of the product under controlled conditions, and eventual free use in consumer tests; and also towards exaggerated use to evaluate potential irritancy, using exaggerated frequency of use, exaggerated product concentration, or occlusive cover to promote skin penetration and enhance irritancy.
Skin reactions under exaggerated exposure conditions do not necessarily mean that a product would be unacceptable under normal use conditions or when misused predictably. Therefore, appropriate standard products must be included in tests to provide relevant comparison when significant skin reaction does occur.
Data will be presented to demonstrate progressive evaluation of irritancy of cosmetics and toiletries, based on expert assessment of visible skin reactions and on analysis of spontaneous and prompted comments about subjective effects, and including appropriate attention to the ethical requirements for tests involving human volunteers.     

Visible skin condition and perception of human facial appearance

Evolutionary psychology suggests that certain human beauty standards have evolved to provide reliable cues of fertility and health. Hence, preferences for some physical characteristics of the face and body are thought to reflect adaptations for the promotion of mate choice. Studies that have investigated facial attractiveness have concentrated mainly on features such as symmetry, averageness and sex‐typical traits, which are developed under the influence of sex steroids. Few studies, however, have addressed the effect of human skin condition on perception of facial appearance in this context, and possible implications for sexual selection. There is now accumulating evidence that skin pigmentation and skin surface topography cues, particularly in women, have a significant influence on attractiveness judgements, as they seem primarily to signal aspects of age and health. This article (i) reviews briefly some of the main determinants of visible skin condition, (ii) presents recent evidence on its signalling value in face perception and (iii) suggests areas for future research with reference to an evolutionary psychology framework.     

Easy classification of traditional Minas cheeses using artificial neural networks and discriminant analysis

The classification of traditional Minas cheese (TMC) from different regions is important to ensure authenticity. Different chemometric approaches were used to discriminate TMCs from three different regions (Serro, Canastra and Araxá) of Minas Gerais, Brazil. The data obtained from the literature were used to develop an artificial neural network and to obtain linear discriminant functions, which were able to classify 100% of cheeses from different regions as a function of physico‐chemical composition. Both chemometric methods can be very useful tools to discriminate TMC from different regions based on physico‐chemical data which are obtained in a very quick and simple way.     

二维非接触人体测量中体型的模糊聚类分析

二维非接触人体测量系统中,围度尺寸需要通过二维至三维的数据转换间接获得。为增强围度预测的精度,应按不同体型类别分别建立预测模型。为避免指标间的信息重复,进行主成分分析,将原有的24项指标归纳为4项综合指标,对人体体型进行客观的综合评价。应用模糊C均值聚类分析进行人体体型分类,分别建立预测模型,以最大隶属度原则对样本进行分类。应用F统计量和聚类有效性函数检验聚类的有效性,并结合实际应用结果确定最佳分类数。     

Glycation induction and antiglycation activity of skin care ingredients on living human skin explants

Glycation is an ageing reaction of naturally occurring sugars with dermal proteins, whose clinical signs may appear in vivo around age 30, and increases steadily/regularly with age. The suppleness of the dermis is affected by the formation of bridges between proteins and sugars (Maillard's reaction). The residues formed (Amadori products, Advanced Glycation End products) as well as the proteins they alter, can be visualized by specific immunostainings. Induced in a few days on living skin explants by methylglyoxal, glycation can be prevented by the application of aminoguanidine HCl, the reference anti-glycation molecule. This model enabled to highlight the anti-glycation activity of substances of vegetal origin such as puerarin and chlorogenic acid.     

In vivo barrier challenge and long‐term recovery in human facial skin

Recently, we developed a biophysical approach to characterize in vivo facial cheek skin as a function of stratum corneum (SC) depth, barrier function and during a 24‐h recovery period. The current study extends this work and characterizes the human facial cheek after barrier challenge and, for the first time, facial SC barrier recovery over a 4‐week period. Changes in the corneocyte size over the 4‐week recovery period, and correlations with changes in Trans‐Epidermal Water Loss (TEWL) were monitored. This approach allows complete characterization of SC barrier function after a full biological regeneration of the SC barrier following tape stripping. The structural and compositional changes in facial cheek were investigated using Attenuated Total Reflectance‐Fourier Transform Infra Red (ATR‐FTIR) spectroscopy, tape stripping, TEWL measurements and image analysis combined with optical microscopy to characterize the SC depth profile during the tape stripping stress and over 4‐week recovery period. TEWL increased significantly from baseline after sequential tape stripping. Corneocyte size decreased with successive tape stripping. An inverse direct correlation was determined between TEWL and corneocyte surface area. After 4 weeks, the corneocyte size and TEWL for the facial cheek recovered 100% from the tape stripping procedure. The in vivo ATR‐FTIR data demonstrated that lipid and sebum components on the surface of the facial cheek SC recovered within 24 h post tape stripping, whereas protein (Amide II) and water components recovered after 1 week.     

Relationship between clinical features of facial dry skin and biophysical parameters in Asians

There have been few reports classifying the biophysical characteristics of Korean women with healthy skin. Consequently, the aim of this study was to find the most useful parameters for categorizing skin types based on a clinical assessment. One hundred and three female volunteers, aged 20-59, participated in this study. We conducted a self-evaluation questionnaire, a clinical assessment of the facial skin, and non-invasive measurements on the cheek under controlled environmental conditions. The questionnaire survey indicated that 72% of respondents had dry skin. However, results of the clinical assessment focusing on skin roughness and scaling of the cheek showed that 6 subjects had very dry skin (6%), 29 had dry skin (28%) and 68 had normal skin with sufficient moisture (66%). We analysed the correlation between the clinical assessment and biophysical parameters. As a result, we obtained six biophysical parameters that had relatively higher correlations with clinical assessment than other parameters. Our study provided general information about the physiological characteristics of normal skin in Korean women and suggested useful parameters for characterizing dry skin.     

基于运动捕捉的骑行运动中人体皮肤形变分析

为揭示在骑行运动过程中人体尺寸变化以及皮肤的形变规律,首先运用OptiTrack 运动捕捉系统采集了骑行运动中人体标记点的位置变化及其运动轨迹,对人体动态变化做定性分析,然后采用体表画线法对骑行运动中人体皮肤形变规律作进一步研究。结果表明：在骑行运动周期过程中,腰部及以上部位的点波动较小,尺寸变化较小,下肢部位点的波动较大,尤其膝部,且垂直方向变化大于水平方向;腿部变化复杂,且在骑行运动中不同区域的变化存在差异,其中围度变化率约在（ －8%,16%）区间,长度变化率在（ －60%,40%）区间;膝部的变化最为明显,变化率最大值达－60%左右,大腿和小腿处的变化较小。     

Influence of topically applied ceramide/phospholipid mixture on the barrier function of intact skin, atopic skin and experimentally induced barrier damage

The influence of a liposomal formulation of a ceramide/phospholipid mixture on the barrier function of the skin in atopic tests, in subjects with healthy skin, and after lipid extraction was tested. The transepidermal water loss and the stratum corneum hydration served as parameters for the evaluation of the influence of the ceramide/phospholipid-mixture treatment on the barrier function. Additionally a barrier-function test with nicotinic acid ester was performed after ceramide/phospholipid-mixture application. Stabilizing effects on the barrier function after application of ceramide/phospholipid-mixture were found only in atopic skin and after lipid extraction but not in healthy skin. The results lead us to expect positive effects of ceramide/phospholipid-mixture only if barrier damage is present.     

Visible skin colouration predicts perception of male facial age, health and attractiveness

Although there is evidence that perception of facial age, health and attractiveness is informed by shape characteristics as well as by visible skin condition, studies on the latter have focused almost exclusively on female skin. Recent research, however, suggests that a decrease in skin colour homogeneity leads to older, less healthy and less attractive ratings of facial skin in both women and men. Here, we elaborate on the significance of the homogeneity of visible skin colouration in men by testing the hypothesis that perception of age, health and attractiveness of (non-contextual) digitally isolated fields of cheek skin only can predict that of whole facial images. Facial digital images of 160 British men (all Caucasian) aged between 10 and 70 were blind-rated for age, health and attractiveness by a total of 147 men and 154 women (mean age = 22.95, SD = 4.26), and these ratings were related to those of corresponding images of cheek skin reported by Fink et al. (J. Eur. Acad. Dermatol. Venereol. in press). Linear regression analysis showed that age, health and attractiveness perception of men's faces could be predicted by the ratings of cheek skin only, such that older men were viewed as older, less healthy and less attractive. This result underlines once again the potent signalling role of skin in its own right, independent of shape or other factors and suggests strongly that visible skin condition, and skin colour homogeneity in particular, plays a significant role in the perception of men's faces.     

Differences in visual perception of age and attractiveness of female facial and body skin

Perception of age and health is critical in the judgement of attractiveness. The few studies conducted on the significance of apparent skin condition on human physical appearance have studied faces alone or isolated fields of images facial skin. Little is known about whether perception of the face matches that of other body parts or if body skin affects overall age and attractiveness perception when presented in combination with facial skin. We hypothesized that independent presentation of female faces, chests and arms (including hands) – cropped from a full face and upper body image – would result in significant differences in perception of age and attractiveness compared to the corresponding composite. Furthermore, we sought to investigate whether relatively young and attractive looking skin on selected, individual parts of the body affects overall perception. Digital photographs of 52 women aged 45–65 years were collected and processed to yield four derivative sets of images: One set showed the composite of all features, i.e. the face, the chest and the arms, whereas the other three were cropped carefully to show each part of the upper body described above independently. A total of 240 participants judged these faces for perceived age and attractiveness. Our results showed significant differences in perception with the chest and the arms being judged significantly younger than the face or composite image of the same women. Moreover, arms and chest images were perceived as more attractive than face and composite images. Finally, regression analysis indicated that differences between the perceived and chronological values of overall age perception could be predicted by age perception of the face and arms. These results continue to support the significance of facial age perception in assessment of a woman’s age, but highlight that body skin also plays a role in overall age impression.