Philippe Bastien

Sensitive skin: an epidemiological study

Background There is a growing awareness that some individuals exhibit heightened skin sensitivity, particularly on the face, and have a high incidence of adverse reactions to cosmetics and toiletries.

PLS generalised linear regression

PLS univariate regression is a model linking a dependent variable y to a set X = {x1 ;:::; xp} of (numerical or categorical) explanatory variables. It can be obtained as a series of simple and multiple regressions. By taking advantage from the statistical tests associated with linear regression, it is feasible to select the signi3cant explanatory variables to include in PLS regression and to choose the number of PLS components to retain. The principle of the presented algorithm may be similarly used in order to yield an extension of PLS regression to PLS generalised linear regression. The modi3cations to classical PLS regression, the case of PLS logistic regression and the application of PLS generalised linear regression to survival data are studied in detail. Some examples show the use of the proposed methods in real practice. As a matter of fact, classical PLS univariate regression is the result of an iterated use of ordinary least squares (OLS) where PLS stands for partial least squares. PLS generalised linear regression retains the rationale of PLS while the criterion optimised at each step is based on maximum likelihood. Nevertheless, the acronym PLS is kept as a reference to a general methodology for relating a response variable to a set of predictors. The approach proposed for PLS generalised linear regression is simple and easy to implement. Moreover, it can be easily generalised to any model that is linear at the level of the explanatory variables. c

A soft, wearable microfluidic device for the capture, storage, and colorimetric sensing of sweat

A soft, skin-mounted microfluidic device captures microliter volumes of sweat and quantitatively measures biochemical markers by colorimetric analysis. Better health? Prepare to sweat Wearable technology is a popular way many people monitor their general health and fitness, tracking heart rate, calories, and steps. Koh et al. now take wearable technology one step further. They have developed and tested a flexible microfluidic device that adheres to human skin. This device collects and analyzes sweat during exercise. Using colorimetric biochemical assays and integrating smartphone image capture analysis, the device detected lactate, glucose, and chloride ion concentrations in sweat as well as sweat pH while stuck to the skin of individuals during a controlled cycling test. Colorimetric readouts showed comparable results to conventional analyses, and the sweat patches remained intact and functional even when used during an outdoor endurance bicycle race. The authors suggest that microfluidic devices could be used during athletic or military training and could be adapted to test other bodily fluids such as tears or saliva. Capabilities in health monitoring enabled by capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible, and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of the skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose, and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH, and concentration of chloride and lactate.

Effects of nonpathogenic gram‐negative bacterium Vitreoscilla filiformis lysate on atopic dermatitis: a prospective, randomized, double‐blind, placebo‐controlled clinical study

Background  Atopic dermatitis (AD) is associated with elevated IgE levels and Th2 responses. The oral administration of nonpathogenic bacteria such as probiotics may improve the course of atopic diseases. It is believed that nonpathogenic bacteria prevent the development of allergic diseases by modulating intestinal immune responses. However, the effects of oral probiotics on AD could not be reproduced in all studies and the direct immunomodulation of the skin‐associated immune response by nonpathogenic bacteria has not yet been investigated.

Ethnic variations in self-perceived sensitive skin: epidemiological survey

To examine possible ethnic variations in perception of sensitive skin, an epidemiological survey was performed in the San Francisco area. Approximately 800 telephone interviews were conducted with women from four different ethnic groups (Afro‐Americans, Asians, Euro‐Americans, Hispanics; approximately 200 women per group). In addition to sensitive facial skin assessments, age and other general skin condition data were collected. 52% of the subjects identified themselves as having sensitive facial skin. There was no statistical difference between the ethnic groups in terms of sensitive skin prevalence. Nevertheless, some differences were noted between ethnic subgroups of sensitive skin. Euro‐Americans were characterized by a higher skin reactivity to wind and tended to be less reactive to cosmetics. Afro‐Americans presented diminished skin reactivity to most environmental factors and a lower frequency of recurring facial redness. Asians appeared to have greater skin reactivity to spicy food, to sudden changes in temperature and to wind, and tended to suffer from itching more frequently. Hispanics presented a lower incidence of skin reactivity to alcohol. The differences in skin sensitivity between ethnic groups concerned mostly factors of skin reactivity and, to a lesser extent, its symptomatology. But, taken together, we note the similarities in comparing how women of varying ethnic backgrounds perceive the sensitive skin condition.

Bifidobacterium longum lysate, a new ingredient for reactive skin

Please cite this paper as: Bifidobacterium longum lysate, a new ingredient for reactive skin. Experimental Dermatology 2010; 19: e1–e8.

Histological features of peripilar signs associated with androgenetic alopecia.

BackgroundA study of the scalp in a large cohort of volunteers with androgenetic alopecia using macrophotographs showed the presence of peripilar signs (PPS) around the hair ostia.ObjectiveThe aim of the present study was to establish the histopathological features related to PPS.DesignProspective clinicopathological study.SettingDepartment of Dermatology, University Hospital of Bologna.PatientsA group of 40 patients (21 males and 19 females) participated in the study. Macrophotographs of the scalp were taken using a Dermaphot camera and PPS were scored using a three-point scale. Hair density and PPS were clinically scored according to reference scales. Two punch biopsies from the photographed area were obtained from each subject and histological analysis was performed on vertical and horizontal sections.ObservationsClinical parameters indicated that PPS were already detectable on scalp with high hair density. Moreover, in patients with high hair density (score >4), a significant relationship was found between the PPS score and the global score for perifollicular infiltrates. Thus PPS are linked to superficial perifollicular lymphocytic infiltrates in early androgenetic alopecia.ConclusionsPPS could be the clinical signs reflecting the presence of perifollicular infiltrates.

Supplementation with oral probiotic bacteria protects human cutaneous immune homeostasis after UV exposure-double blind, randomized, placebo controlled clinical trial

There is now strong evidence that probiotic bacteria can regulate inflammatory immune responses. Here, we analyzed whether oral supplementation with the probiotic bacterial strain Lactobacillus johnsonii (La1) could interfere with skin immune status following UV exposure. A randomized, double-blind, placebo controlled clinical trial was conducted with 54 healthy volunteers receiving either La1 or placebo, during six weeks prior to solar-simulated UV irradiation. Blister roofs and skin biopsies were recovered 1, 4 and 10 days after UV exposure from un-irradiated and irradiated skin and used for immunohistochemical analysis and mixed epidermal cell lymphocyte reaction (MECLR), respectively. La1 supplementation did not prevent the UV-induced phenotypic maturation of Langerhans cells (LCs) or the decrease in MECLR in irradiated skin samples, one day post-irradiation. On day 4, MECLR was still decreased in the placebo group, with a parallel reduction in the CD1a LC marker in irradiated epidermis. In contrast, the allostimulatory capacity of epidermal cells was totally recovered in the La1 group correlating with the normalization of CD1a expression within the epidermis. For the first time, the results provide evidence that ingested probiotic bacteria accelerate the recovery of skin immune homeostasis after UV-induced immunosuppression.

In vivo epidermal thickness measurement: ultrasound vs. confocal imaging.

Background/purpose: In this study, in vivo skin imaging methods, ultrasound (US) and confocal microscopy (CM) were compared with regards to their accuracy in measuring the epidermal thickness. In addition an attempt was made to clarify the biological significance of the second echo‐rich line observed on US skin images, i.e. whether it represents the dermal–epidermal junction or the papillar–reticular dermis limit.

A broad‐spectrum sunscreen prevents UVA radiation‐induced gene expression in reconstructed skin in vitro and in human skin in vivo

Abstract:  The efficacy of sunscreens to protect against ultraviolet (UV) A radiation is usually assessed by measuring erythema formation and pigmentation. The biological relevance of these endpoints for UVA‐induced skin damage, however, is not known. We therefore carried out two complementary studies to determine UVA protection provided by a broad‐spectrum sunscreen product at a molecular level by studying UVA radiation‐induced gene expression. One study was performed on human reconstructed skin in vitro with a semi‐global gene expression analysis of 227 genes in fibroblasts and 244 in keratinocytes. The second one was conducted in vivo in human volunteers and focused on genes involved in oxidative stress response and photo‐ageing (haeme oxygenase‐1, superoxide dismutase‐2, glutathione peroxidase, catalase, matrix metalloproteinase‐1). In‐vitro UVA radiation induced modulation of genes involved in extracellular matrix homeostasis, oxidative stress, heat shock responses, cell growth, inflammation and epidermal differentiation. Sunscreen pre‐application abrogated or significantly reduced these effects, as underlined by unsupervised clustering analysis. The in vivo study confirmed that the sunscreen prevented UVA radiation–induced transcriptional expression of the five studied genes. These findings indicate the high efficacy of a broad‐spectrum sunscreen in protecting human skin against UVA‐induced gene responses and suggest that this approach is a biologically relevant complement to existing methods.