Didier Saint-Léger

Objective: The re-greasing process and kinetics of the human scalp, post shampooing, has been previously documented, in vivo, on a few Caucasian subjects. The objective of the presented research is to extend such knowledge over 7 different ethnic groups. Methods: The post shampooing re-greasing kinetics of the scalp was studied on 1325 subjects...

A review of the various facets of the colour of human skin is proposed.It aims first at illustrating the paradoxical association of the remarkable recent scientific advances that characterize changes in the skin colour, with some totally inappropriate or out-dated phrasings used in its communication. As a second objective, it aims at proposing an a...

Senescence of people represents a global expression of obsolescence of their organs, tissues, cells and constitutive molecules. Skin, similarly to any other organ, is ageing in particular ways. Over the past century, the time effects on skin have been expressed differently. Skin of any individual presently engaged in the Third Age looks different f...

Striae distensae represent a common skin condition, corresponding to a physiological event particularly developed during adolescence, pregnancy and gain in body weight. In addition, these lesions are induced by the Cushing syndrome or an intense corticotherapy. The viscoelastic properties of the skin are altered and vary according to the severity o...

Skin ageing and gender influences on the scalp have been seldom studied. We revisited the changes in the interfollicular scalp. The study was performed on a population of 650 volunteers (300 women and 350 men) for over 7 years. Three age groups were selected in both genders, namely, subjects aged 20-35, 50-60, and 60-70 years. The hair status was f...

The facial skin tone of two groups of Chinese women from Shanghai was compared using standard colorimetric space techniques during a 6-month interval between January and July 2011. During the study period, one group of women (n = 40) applied a potent sun-protective cosmetic product daily, while the other group (n = 40) did not use any sun protectio...

Objective: This preliminary study investigated both the impact of oily skin on quality of life (QoL) and the agreement between subjective oily skin self-assessment and objective skin surface sebum measurement in young to middle-aged Chinese women in Beijing. Methods: A 18-item Chinese version of the Oily Skin Self-Image Questionnaire (OSSIQ) was...

Through the hybrid term ‘Cosmeceuticals’, the present paper aims at reviewing some scientific and legal sources of ambiguities or uncertainties that, in many regulatory cases, added confusions to the respective roles of drugs and cosmetics. The origins of such questions, likely arose from new anti-ageing claims from the cosmetic industry in the lat...

After measurement of individual growth rates, natural hair fibres from Asian and Caucasian subjects were analysed using scanning electron microscopy. In total, more than 1000 hairs were analysed. Measurements of diameter, medulla and interscale distance (average distance between two successive cuticle scales) show these parameters strongly correlat...

Ferulic acid (F.A) receives significant interest in the beauty industry with regard to its skin-whitening and anti-oxidant properties. However, its use in cosmetics is limited due to pH- and temperature-related instabilities. In this study, we investigated the stability of F.A in eight different prototype formulae. The results confirmed that in our...

Objective: To understand the aging of natural hair and some specific parameters related to hair anagen. Methods: A case of Chinese lady's natural hair 4.3 m in length and 26 year growing phase was studied by means of characterization of physical properties, electronic microscopy and chemical/ biochemical analysis. Results: As a physical fiber, this...

Synopsis Examination of very long hair (length>2.4m) using a large range of evaluation methods including physical, chemical, biochemical and microscopic techniques has enabled to attain a detailed understanding of natural ageing of human hair keratin fibres. Scrutinizing hair that has undergone little or no oxidative aggression-because of the absen...

Cosmetic habits show a strong diversity worldwide. The same applies to procedures that are considered as basic hygiene acts such as shampooing. Apart from common traditional shampoo routine, a special shampoo procedure, 'dry' wash is daily performed in Chinese hair salons. Without pre-wetting step, hairdresser applies the shampoo directly to dry ha...

Androgenetic alopecia (AGA) is a common yet poorly understood condition. In particular, the significance of inflammatory cells close to the infrainfundibulum of transitional hairs remains obscure. This study was conducted in 20 men who used a lotion containing the antimicrobials, piroctone olamine and triclosan, regularly for 18 months. At entry, m...

Background: For many years, cosmetic scientists have attempted to measure the physical features of human hair, such as its shape and colour, as these can be artificially modified using cosmetic products. With regard to hair shape, previous anthropologic studies have emphasized its variability within and between human ethnic groups. Many studies ha...

Biological rhythms are numerous and vary according to periodicity and amplitude. Variations over the course of a day, particularly circadian rhythms have been reported in the skin of the face and forearms. However, little information is available about daily biorhythms of the scalp. The aim of the present study was to explore the chronophysiology o...

Biological rhythms are numerous and vary according to periodicity and amplitude. Variations over the course of a day, particularly circadian rhythms have been reported in the skin of the face and forearms. However, little information is available about daily biorhythms of the scalp. The aim of the present study was to explore the chronophysiology o...

Human hair has been commonly classified according to three conventional ethnic human subgroups, that is, African, Asian, and European. Such broad classification hardly accounts for the high complexity of human biological diversity, resulting from both multiple and past or recent mixed origins. The research reported here is intended to develop a mor...

The hydroxy acids are widely used in skin creams because of their exfoliating and rejuvenating effect on photoaged skin. As a member of this family, the salicylic acid derivative known in the literature as 2-hydroxy-5-octanoyl benzoic acid or beta-lipohydroxy acid has also been proposed as an exfoliant and as a treatment of photoaged skin and acne....

Silicon image sensor (SIS) technology was recently introduced as an innovative tool (SkinChip, L'Oréal) providing sensitive imaging of the skin capacitance. This method can detect discrete focal variations in skin surface hydration, and thus early discrete manifestations of skin irritation induced by surfactants. In the present in vivo study, 2 nea...

In some individuals, dandruff may be recurrent and even chronic. This represents a difficult-to-treat condition. Excessive hair shedding and diffuse alopecia may develop. To evaluate the chronobiological aspects of dandruff, hair shedding and alopecia. This study was performed in eight men suffering from such a scalp condition. They were examined 4...

Hair condition may be adversely affected by the state of the underlying, fostering, nourishing, and hair-bearing scalp, which means that maintaining the scalp in a good condition is a prime requisite to prevent hair from potentially unpleasant, unattractive, or disfiguring defects. Hence a paramount need for providing the most appropriate care to t...

Dandruff, a scaly disorder of the scalp, is a benign affliction shared by about 45% of the human population, irrespective of sex and ethnicity. Paradoxically, some textbooks on Dermatology even ignore it.

Dandruff is known to be controlled by fungistatic shampoos active against Malassezia spp. These products also remove the loosely attached scales. This study was performed to assess the effect of a 5-min residence time on the efficacy of antidandruff shampoos. Two commercially available shampoos were used in two groups of 21 panelists with severe da...

Chronobiology governing the hair cycle is a fascinating and complex process. Both the hair growth cycle and the hair shaft growth are coordinated and depend on the interplay of different biological signals and various exogenous stimuli. A latency period may occur between hair shedding (teloptosis, exogen phase) and the early emergence of the next a...

Modern therapeutic approaches allow to control sebaceous secretion but knowledge about the sebaceous gland and its precise function within the pilosebaceous unit is still insufficient. Steroid hormones are the principal albeit not exclusive regulators of the sebaceous glands. Three phases may be distinguished in sebaceous physiology: secretion-prod...

Modern therapeutic approaches allow to control sebaceous secretion but knowledge about the sebaceous gland and its precise function within the pilosebaceous unit is still insufficient. Steroid hormones are the principal albeit not exclusive regulators of the sebaceous glands. Three phases may be distinguished in sebaceous physiology: secretion-prod...

Background: Ultraviolet light radiations (UVR) may be responsible for hair cycle synchronization and telogen effluvium in the animal and humans. The effect if any of cumulative UVR on chronic hair shedding and androgenic alopecia (AGA) is largely unknown. Objective: To compare the severity of AGA with the extent of solar elastosis. Method: The pres...

Based on the clinical presentation of some skin pigmentation disorders it is thought that a bicompartmental functional system exists in the epidermal melanocyte population. It corresponds to the perifollicular and interfollicular compartments, respectively. The present study was undertaken looking for the presence of such a system on scalp unaffect...

The analysis of the lipids extracted from human hair by silica-gel-column liquid chromatography permitted an isolation of the fraction enriched in free ceramides. These were identified by GC/MS and are related to ceramide classes 2 and 5 in which the long-chain base was predominantly sphinganine. This differs from that observed in the free ceramide...

The human pilosebaceous follicle shows an extreme diversity with regard both its variation according to its localisation along the human body, and the various physiological dependences of the two tissues which comprise the pilosebaceous follicle. These latter, highly differentiated toward specialised synthesis (proteins, lipids) have their own spec...

The effects of topically applied sodium lauryl sulfate were studied in vivo, in man, through noninvasive methods and compared with those obtained in vitro, using human stratum corneum as a model. The results show that the very marked increase of transepidermal water loss obtained in vivo cannot be related to any removal of epidermal lipids. The mos...

We utilized a sebum-sensitive adhesive film, Sebutape, to visualize the pore patterns of women with and without acne with computerized image analysis. In normal young women, we found a positive correlation between the number of active sebaceous follicles and total sebum excretion. When seborrhea was intense, this correlation was however lost. The s...

Topical corticosteroids are widely used in cutaneous diseases. Although their mode of action on different skin compartments has been documented, little is known about their effects on the human sebaceous gland. We investigated the effects of two corticosteroids of differing potency on the excretion of sebum by means of two validated techniques: the...

The systemic long-term corticosteroid treatment administered to kidney graft recipients (KGR) within the framework of the required immunosuppressive therapy induces an atrophy of the skin, from the sixth month onwards. We studied the effect of topical all-trans retinoic acid (0.05%; Galderma Labs.) applied to the forearms of 27 KGR (14 men, 13 wome...

New fatty polyenic (linoleic, linolenic, arachidonic, linoelaidic) mono esters of erythromycin A have been synthesized by using various reagents such as acyl chloride, carboxylic acid anhydride, and mixed carbonic anhydride. These different ways of activating the fatty acid allowed a regioselectivity of esterification at position 2' of the desosami...

Changes in the composition of human stratum corneum lipids (SCL) were studied at various times after an induced inflammatory reaction. Three kinds of injury were inflicted: 3 MED of ultraviolet radiation, 3 MED of solar radiation or 30 strippings of the horny layer with plastic tape. The SCL were evaluated qualitatively and quantitatively at short...

In one of his books, written at the beginning of this century, Raymond Sabouraud devotes some 280 pages to the history of dandruff. Their reading illustrates how, from the Greeks to Sabouraud's era, this desquamative disease has been subjected to endless doctrinal and scientific conflicts, long before the so-called "present" controversies. One of t...

Images of the hamster flank organ were obtained in vivo by high resolution ultrasound (B-scan). The planimetric measurements of the ultrasonic image that determined the size of the flank organ, with a reproducibility of about 10%, highly correlated with the measurements of histological sections. This new method provides a simple and non-invasive me...

This paper describes an original in vivo device to investigate and quantify cutaneous resorption of sebum. Such a phenomenon was explored using a photometric determination of residual skin surface lipids at different times following initial deposits of known amounts of artificial sebum on demarcated areas. The technique was carried out on seven hea...

Lipids of the stratum corneum are implicated in cohesion and desquamation of the stratum corneum as well as in the maintenance of normal barrier function. Evidence linking the intercellular lipids to such processes has mainly been derived from studies on acquired or inherited diseases of lipid metabolism manifesting abnormalities in the structure a...

Stratum corneum lipids (SCL) were collected on the right and left legs of 50 subjects of varying ages and skin dryness. The level of dryness and composition of the lipid was the same on both sides. While skin dryness continuously increased with age, the composition of SCL showed a constant profile from the 50s. Aging was mostly associated with a de...

Stratum corneum lipids (SCL) were collected on the right and left legs of 50 subjects of varying ages and skin dryness. The level of dryness and composition of the lipid was the same on both sides. While skin dryness continuously increased with age, the composition of SCL showed a constant profile from the 50s. Aging was mostly associated with a de...

Synopsis Current thinking implicates P. ovale as the cause of dandruff; the condition invariably resolves when this yeast is suppressed. However, P. acnes and coagulase-negative cocci are also abundant on the scalp. A contributory role for those members of the resident microflora has not been ruled out. We used a new technique to collect and weigh...

The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.

An in vitro study of the oxidation of squalene, and a description of factors acting on this transformation are presented. Thin layer chromatography was used to quantify the products generated by different oxidation processes. The results clearly show that squalene is a highly effective oxygen-scavenging agent. Its oxidation may first induce comedog...

Skin surface lipids and lipids from open and closed comedones in acne patients were analysed by thin layer chromatography. The results showed that these lipids were enriched in polar lipids, as compared with the skin surface lipids obtained from controls without acne. In both open and closed comedones, these polar lipids appeared to be derived main...

Measurement of Sebum Excretion Rate (SER) in patients is a time-consuming test. It is now possible to measure SER 1 h after having degreased the forehead with a 70% ethanol solution. The skin surface lipids (SSL) collected during this time have similar composition to those collected for up to 7 h. A qualitative and quantitative study of sebaceous e...

Photoacoustic spectroscopy (PAS) was used to evaluate light absorption by solid samples. Application of this technique to the human stratum corneum (SC) was used to investigate the influence of some constituents of SC (water, lipids, hydrophilic substances) on ultraviolet (UV) absorption by this tissue. The results showed that the water content of...

A modified photometric technique has shown considerable differences between the refatting kinetics of the scalp and forehead. The refatting on the forehead occurs rapidly, probably due to the large follicular reservoir. The follicular reservoir of the scalp, which bears a large terminal hair, is much smaller and so the refatting time is longer. Thu...

A new routine testing procedure of qualitative analysis of skin surface lipids in man is proposed. This method combines the easiness of sampling, by direct contact between ground glass plates and skin fat, with accurate thin layer chromatographic analysis of the five basic parameters (cholesterol, free fatty acids, triglycerides, wax esters, squale...

The purpose of this study is to present a rapid, simple, and accurate method for quantitation of SSL in man. The technique which is derived from the works by Schaefer and Kuhn-Bussius, employs a series of clearn ground glass plates, and an apparatus, the Lipometre, for the determination of the variation of light transmission across the plates as a...