Morphometric characteristics of feminine eyebrows: variations with ethnicities and age

OBJECTIVE

To explore some morphological features of the eyebrows of women of different ethnicities and ages.

MATERIALS AND METHODS

Standard digital photographs of 3600 women of six ethnicities, aged 18-84 years, previously used to describe the morphology of the human eyes, allowed us to focus on their eyebrows, as supplementary and opportunistic study. Photographs of both eyebrows were analysed partly by manual markings and automatically by dedicated algorithms. Six parameters of the eyebrows were recorded: length, waviness/curvature, oblique aspect, size (vertical height), total surface and hair coverage (density).

RESULTS

Most criteria present ethnic specificities. These are: length (longer eyebrows of Indian, shorter among African women); waviness where the straighter eyebrows were found among Chinese and Japanese women. In general, the longer the eyebrows, the higher their waviness and vice versa. Thickness (or height) of the eyebrows presents a wide ethnic variability as well as hair coverage, where African women present the lower hair density, inversely to Indian women. The same holds true with regard to the total surface of eyebrows, of a large variability (by about four times). Some criteria appear more individually dependent than ethnic-specific, such as the oblique positioning, at the exception of Indian women with less oblique eyebrows. In all subjects, the criteria of both eyebrows (Left vs. Right) were found to be highly correlated (r > 0.7, P < 0.001).

CONCLUSION

The present investigation brings new findings on a scarcely studied facial element, the morphologic features of which are, for most, ethnic-dependent. As applied consequences, the results of the present work pave the road to better adapt adorning procedures of the eyebrows vis-à-vis ethnic and age specificities.

Isolation and identification of human hair ceramides

Synopsis 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 ceramides found within the stratum corenum.

'Cosmeceuticals'. Of men, science and laws…

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 late 80s which faced a rather old regulatory backdrop. Based on the analysis of some legal statements and scientific facts from a 2012 vision, this review tentatively aims at re-defining the respective roles of these two branches that both fill the two vital needs of humans, 'being' and 'well-being'.

Alterations in the composition of human stratum corneum lipids induced by inflammation

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 intervals. Marked changes in the SCL were detected between the 9th and the 11th day. With all 3 insults, the SCL increased quantitatively and showed a more polar pattern, i.e. a decrease in neutral fractions and an increase in the polar ones. These changes were synchronous with the marked shedding which occurs between the 9th and the 11th day. These findings have implications for the role of lipids in stratum corneum cohesiveness.

New fatty monoesters of erythromycin A

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 desosamine ring or position 4" of the cladinose ring of erythromycin A. The in vitro antibacterial properties of these new esters against members of the resident flora of the human skin were determined and compared with those of erythromycin A. The number and the stereochemistry of the double bonds seem to play a crucial role in the expression of the in vitro antibacterial activity.

Imaging the hamster flank organ by an ultrasonic technique: a new approach to animal tests

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 method for determining the size of the hamster flank organ after various treatments which does not involve the killing of the animal under investigation.

An original procedure for quantitation of cutaneous resorption of sebum

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 healthy subjects. The chosen area was the anterior aspect of the forearm, owing to the very low sebum production of this site, less than the sensitivity of the measuring instrument. The kinetics of absorption of applied sebum turned out to be hyperbolic-like and well correlated with experimental results (r = 0.992), allowing a mathematical determination of the initial velocity of penetration of sebum into the skin, reaching 20 micrograms/cm2.min for a standard program including a mean initial deposit of 116 micrograms/cm2. This kinetics actually does not fit with a true percutaneous absorption of lipids but is compatible with that of absorption into the stratum corneum. It conveys the faster absorption of the latter for sebum, a well-known but not so far quantified property of stratum corneum. The model here described is not at once transposable to skin areas with high sebum production since, quite obviously in such zones, the stratum corneum is permanently saturated with skin surface lipids. Therefore, the conclusions of this work cannot be correlated with the regreasing parameters studied so far on the forehead, but they provide interesting data about the evolution of sebum following its output onto the skin surface and therefore a better understanding of sebaceous physiology.

A possible role for squalene in the pathogenesis of acne. I. In vitro study of squalene oxidation

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 comedogenesis and, as a secondary event, cause a large reduction in oxygen tension in the human pilo-sebaceous duct. Porphyrins were confirmed to be highly efficient catalytic factors in the squalene oxidation process. The relationships between comedogenesis, bacterial colonization, and the role of sebum in the pathogenesis of acne are discussed in the light of these findings.

A possible role for squalene in the pathogenesis of acne. II. In vivo study of squalene oxides in skin surface and intra-comedonal lipids of acne patients

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 mainly from the oxidation of squalene, which is in agreement with our previous in vitro results. We suggest that squalene oxidation is the link between comedogenesis and bacterial colonization, and based on this, we propose a hypothesis of the pathogenesis of acne.

Practical study of qualitative and quantitative sebum excretion on the human forehead

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 excretion, on 18 volunteers, from 1 to 7 h after having cleansed the forehead, showed that the refatting kinetics, in all subjects, obeyed the same mathematical law, independent of the subjects' individual SER.

A comparative study of refatting kinetics on the scalp and forehead

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. Thus, sebum excretion and sebum production rates probably correlate better on the scalp than on the forehead, and we suggest that the scalp may be a better site than the forehead for investigating sebaceous gland physiology.

The lipometre: an easy tool for rapid quantitation of skin surface lipids (SSL) in man

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 function of the fat deposited on them. Results on 32 adults, males and females, show that the first four iterative samplings, at constant pressure, on the same forehead area follow an identical physical law independently of whether the skin is fatty or dry. This law affords a precise definition of the Casual-Level, its quantification and its correlation with skin patterns. It is consequently possible, either as an investigative or a routine technique, to predict the total amount of SSL with good accuracy within 2 min. The SSL, for non-pathological skins, fall within the range 150 microgram/cm2 to 900 microgram/cm2 which is in good agreement with values quoted in the literature.