Test design and results of a method performance characterization study for SPF and UVA-PF testing.

Objective: This paper presents the experimental design, the statistical model, performance criteria and results of a method performance study conducted in order to characterize the performance of alternative methods for SPF and UVA-PF testing. The performance of alternative methods is characterized against the performance of the ISO 24444 and ISO 24443 methods.

Methods: A factorial experimental design was implemented.

Performance assessment of the Double Plate method (ISO23675) in ALT-SPF Consortium: A highly reproducible and accurate in vitro method to determine SPF.

Objective: To perform a comprehensive statistical characterization of the Double Plate method (ISO 23675) as a potential in vitro alternative to the in vivo reference method (ISO 24444:2019) for determining the sun protection factor (SPF).

Methods: Five qualified laboratories were involved in testing the Double Plate method, as part of a large-scale ring test conducted by the International Consortium 'ALT-SPF'. About 32 sunscreen products, reflecting diverse global formulations, were tested using both the in vivo reference method and the Double Plate method.

What defines dry skin? Correlating a range of skin hydration parameters with In Vivo Confocal Raman Spectroscopy.

Objective: While there are a wide range of approaches for the assessment of skin hydration, it is not always clear how data from them relate to one another or to the skin itself. With the development of in vivo Confocal Raman Spectroscopy (ICRS), it has become possible to measure water concentration as a function of protein/depth within the stratum corneum (SC). This article reports a comparison between electrical skin hydration measures/visual/optical grading and water concentration profiles measured using ICRS, to better understand the relationship between these approaches.

Sunscreens - another endangered species?

Skin cancer continues to increase in incidence year-on-year and represents the most common form of cancer across the globe. Every human undergoes premature ageing, particularly on the face, neck and hands. Both phenomena are driven primarily by chronic, daily exposure to solar ultraviolet radiation (UVR).

A New Model to Simulate Human Facial Appearance, Accurately, and Realistically, across Age and Ethnicity.

Background: The human population is aging globally, and there is significant, growing interest in modeling and simulating facial appearance.

Methods: The authors describe a new means to model and simulate aging in facial images, using an approach based entirely on 3D whole-face data collected from 1250 female subjects, across 5 ethnicities, ages 10-80.

Results: Three models were built, each describing changes with age within each ethnic group, namely shape, color, and topography.

Visual Perception of British Women's Skin Color Distribution in Two Nonindustrialized Societies, the Maasai and the Tsimane'.

In women with lightly pigmented skin in particular, facial skin color homogeneity decreases with age, primarily due to chronic exposure to solar ultraviolet radiation (UVR), leading to a decrease in perceived health and attractiveness. Perception of female skin may be influenced by continuous exposure to, and thus familiarity with, age-related changes in visible skin condition in a given society. Men and women of two traditional societies, the Maasai (Tanzania) and the Tsimane' (Bolivia), unfamiliar with lighter colored skin, judged images of British women's facial skin for age, health, and attractiveness.

Topical delivery of hexamidine.

Hexamidine diisethionate (HEX D) has been used for its biocidal actions in topical preparations since the 1950s. Recent data also suggest that it plays a beneficial role in skin homeostasis. To date, the extent to which this compound penetrates the epidermis has not been reported nor how its topical delivery may be modulated.

Understanding age-induced alterations to the biomechanical barrier function of human stratum corneum.

Background: The appearance and function of human skin are dramatically altered with aging, resulting in higher rates of severe xerosis and other skin complaints. The outermost layer of the epidermis, the stratum corneum (SC), is responsible for the biomechanical barrier function of skin and is also adversely transformed with age. With age the keratin filaments within the corneocytes are prone to crosslinking, the amount of intercellular lipids decreases resulting in fewer lipid bilayers, and the rate of corneocyte turnover decreases.

Preparation and characterisation of hexamidine salts.

Hexamidine diisethionate (HEX D) has been used in the personal care industry and in a number of over-the-counter (OTC) drug products as an antimicrobial agent since the 1950's. Recently, the compound has also been investigated for its beneficial effects on skin health. Surprisingly, there is only limited information describing the physicochemical properties of this compound in the literature.

Determination of the Action Spectrum of UVR-Induced Mitochondrial DNA Damage in Human Skin Cells.

Biological responses of human skin to UVR including cancer and aging are largely wavelength-dependent, as shown by the action spectra of UVR-induced erythema and nuclear DNA (nDNA) damage. A molecular dosimeter of UVR exposure is therefore required. Although mitochondrial DNA (mtDNA) damage has been shown to be a reliable and sensitive biomarker of UVR exposure in human skin, its wavelength dependency is unknown.

A seminar on gardens for the health of the skin.

This is a report on a seminar held on January 12, 2013, at the Regional Dermatology Training Centre in Tanzania, sponsored by the International Society of Dermatology as part of its Taskforce Program for Skin Care for All: Community Dermatology. There were four themes: (i) Gardens attached to health centers increase their attractiveness and result in increased attendance and, thus, increase the utilization of effective skin care interventions. Literature on the positive effect of greenery surrounding health centers on health and the environment is reviewed.

Self-assembly of palmitoyl lipopeptides used in skin care products.

The self-assembly of three cosmetically active peptide amphiphiles C16-GHK, C16-KT, and C16-KTTKS (C16 denotes a hexadecyl, palmitoyl chain) used in commercial skin care products is examined. A range of spectroscopic, microscopic, and X-ray scattering methods is used to probe the secondary structure, aggregate morphology, and the nanostructure. Peptide amphiphile (PA) C16-KTTKS forms flat tapes and extended fibrillar structures with high β-sheet content.

Visual attention to and perception of undamaged and damaged versions of natural and colored female hair.

Female hair color is thought to influence physical attractiveness, and although there is some evidence for this assertion, research has yet not addressed the question if and how physical damaging affects the perception of female hair color. Here we investigate whether people are sensitive (in terms of visual attention and age, health and attractiveness perception) to subtle differences in hair images of natural and colored hair before and after physical damaging. We tracked the eye-gaze of 50 men and 50 women aged 31-50 years whilst they viewed randomized pairs of images of 20 natural and 20 colored hair tresses, each pair displaying the same tress before and after controlled cuticle damage.

Variation of stratum corneum biophysical and molecular properties with anatomic site.

Several serine protease enzymes are known to be involved in both normal desquamation and the inflammatory processes of the skin. Alteration in the activity of these proteases should also affect corneocyte maturity and size as well as stratum corneum thickness. The aim of the present work was to characterise the baseline changes in corneocyte size, corneocyte maturity, selected protease activity (specifically, Kallikreins-5 and 7, tryptase), protein content and trans-epidermal water loss (TEWL) as a function of anatomic site.

Interaction of skin color distribution and skin surface topography cues in the perception of female facial age and health.

Background: Skin color distribution and skin surface topography are the predominant drivers of the variation in visible skin condition, and this variation affects one's perception of age and health. Recent research, however, has shown that the strength of the impact of these features on perception differs such that skin surface topography is a stronger indicator of age, while skin color distribution is more strongly linked to health perception.

Objectives: To examine further the relative contribution and interaction effects of skin color distribution and surface topography cues on perception by considering small changes of these features.

Visible changes of female facial skin surface topography in relation to age and attractiveness perception.

Objectives: Evolutionary psychology suggests that a woman's age and physical appearance are important mate choice criteria. Given that changes in female facial skin surface topography are important, prominent visible signs of aging, male perceptual sensitivity for variation in this trait may also affect preference and attractiveness judgment.

Methods: Two experiments were conducted to investigate perception (Experiment 1) and noticeability (Experiment 2) of skin surface topography manipulations in facial images of six British women, aged 45-65 years.

Chronic sun damage and the perception of age, health and attractiveness.

Young and healthy-looking skin is a feature that is universally admired and considered attractive among humans. However, as we age, skin condition deteriorates due to a variety of intrinsic and extrinsic factors determined not only by genetics and physiological health but also by behaviour and lifestyle choice. As regards the latter, cumulative, repeated exposure to solar ultraviolet radiation (UVR) is linked intrinsically to the induction of specific types of skin cancer and the expression of cutaneous damage markers responsible for the majority of the visible signs of skin ageing.

Visual attention to variation in female facial skin color distribution.

Objectives: Visible skin condition of women is argued to influence human physical attraction. Recent research has shown that people are sensitive to variation in skin color distribution, and such variation affects visual perception of female facial attractiveness, healthiness, and age.

Methods: The eye gaze of 39 males and females, aged 13 to 45 years, was tracked while they viewed images of shape- and topography-standardized stimulus faces that varied only in terms of skin color distribution.

New insights into skin appearance and measurement.

When viewing the human face, the eye is drawn automatically to the areas of uneven topography and high color contrast, and the perception of skin age and attractiveness is dependent on these features. Although it is well recognized that topographic features, such as lines and wrinkles, contribute to the perceived age of skin and many cosmetic procedures are directed toward modifying these, the contribution of color contrast to the perceived age of skin has been less widely studied. A new technique, spectrophotometric intracutaneous analysis, is able to measure and characterize the distribution of chromophores in aging human skin and represents a significant advance in evaluation of the role color contrast plays in perception of the aging human face.

Color homogeneity and visual perception of age, health, and attractiveness of female facial skin.

Background: Evolutionary psychology suggests that skin signals aspects of mate value, yet only limited empirical evidence exists for this assertion.

Objectives: We sought to study the relationship between perception of skin condition and homogeneity of color/chromophore distribution.

Methods: Cropped skin cheek images from 170 girls and women (11-76 years) were blind-rated for attractiveness, healthiness, youthfulness, and biological age by 353 participants.

Ultraviolet A radiation: testing and labeling for sunscreen products.

Conceptually, sunscreen products are quite simple. The ultraviolet (UV) filters in these products reduce the "dose" of solar energy to which the skin is exposed. Underlying this empirical notion are many complexities including measures of product efficacy and how to communicate this to consumers.

Solar ultraviolet radiation: definitions and terminology.

In the rapidly developing field of photobiology as it relates to solar ultraviolet radiation (UVR), there is a need as never before to ensure that definitions and terminology are current, correct, and standard. This article provides a basic definition of UVR; a review of correct UVR radiometric symbols, units, and nomenclature; defines extraterrestrial and terrestrial solar UVR; and reviews the measurement of biologically effective dose of solar UVR in humans.