Influence of survival, promotion, and growth on pattern formation in zebrafish skin.

The coloring of zebrafish skin is often used as a model system to study biological pattern formation. However, the small number and lack of movement of chromatophores defies traditional Turing-type pattern generating mechanisms. Recent models invoke discrete short-range competition and long-range promotion between different pigment cells as an alternative to a reaction-diffusion scheme. In this work, we propose a lattice-based "Survival model," which is inspired by recent experimental findings on the nature of long-range chromatophore interactions. The Survival model produces stationary patterns with diffuse stripes and undergoes a Turing instability. We also examine the effect that domain growth, ubiquitous in biological systems, has on the patterns in both the Survival model and an earlier "Promotion" model. In both cases, domain growth alone is capable of orienting Turing patterns above a threshold wavelength and can reorient the stripes in ablated cells, though the wavelength for which the patterns orient is much larger for the Survival model. While the Survival model is a simplified representation of the multifaceted interactions between pigment cells, it reveals complex organizational behavior and may help to guide future studies.

Facial UV photo imaging for skin pigmentation assessment using conditional generative adversarial networks.

Skin pigmentation is associated with skin damages and skin cancers, and ultraviolet (UV) photography is used as a minimally invasive mean for the assessment of pigmentation. Since UV photography equipment is not usually available in general practice, technologies emphasizing pigmentation in color photo images are desired for daily care. We propose a new method using conditional generative adversarial networks, named UV-photo Net, to generate synthetic UV images from color photo images. Evaluations using color and UV photo image pairs taken by a UV photography system demonstrated that pigment spots were well reproduced in synthetic UV images by UV-photo Net, and some of the reproduced pigment spots were difficult to be recognized in color photo images. In the pigment spot detection analysis, the rate of pigment spot areas in cheek regions for synthetic UV images was highly correlated with the rate for UV photo images (Pearson's correlation coefficient 0.92). We also demonstrated that UV-photo Net was effective for floating up pigment spots for photo images taken by a smartphone camera. UV-photo Net enables an easy assessment of pigmentation from color photo images and will promote self-care of skin damages and early signs of skin cancers for preventive medicine.

Dermoscopic assessment of xerosis severity, pigmentation pattern and vascular morphology in subjects with physiological aging and photoaging.

BACKGROUND: Skin aging can be classified as either physiological or pathological aging. Pathological aging is most often due to chronic sunlight exposure (photoaging). Age-dependent changes in dermoscopic features of normal skin have not previously been well defined. OBJECTIVES: We compared the dermoscopic features of skin from non-elderly subjects, elderly subjects with physiological aging, and elderly subjects with photoaging. MATERIALS AND METHODS: We enrolled 40 non-elderly subjects aged 20-60 years, 40 elderly subjects aged >60 years with physiological aging, and 40 elderly subjects aged >60 years with photoaging. Skin from the lower legs of subjects was examined by dermoscopy. RESULTS: Compared with non-elderly subjects, dermoscopic examination of elderly subjects with physiological aging and photoaging revealed various degrees of xerosis (mild: scaling limited to skin furrows; moderate: scaling extending beyond skin furrows with accentuation of skin markings; severe: plate-like scaling extending beyond skin furrows with formation of deep skin fissures). In addition, dermoscopic examination of skin from elderly subjects with photoaging showed increased prevalence of uneven pigmentation (small brown globules, reticular pigmentation, and homogeneous pigmentation in a patchy distribution) and vascular telangiectasia (linear and branching vessels). CONCLUSION: This study provides a novel dermoscopic grading system to evaluate the severity of xerosis and demonstrates the application of dermoscopy for the accurate assessment of subtle morphological changes (including pigmentation pattern and vascular structures) associated with physiological aging and photoaging.

Understanding rates of genital-anal injury: Role of skin color and skin biomechanics.

PURPOSE: A series of studies suggest that non-Hispanic White women have significantly more injuries than non-Hispanic Black women after sexual assault and consensual sexual intercourse. One explanation for this difference is that the degree of skin protection may vary as skin mechanics and skin pigmentation vary. The aim of the study was to determine the association among genital-anal injury, skin color, skin viscoelasticity and skin hydration in women following consensual sexual intercourse when controlling for age, smoking history, body mass index (BMI), sun exposure, and health status. PROCEDURES: We employed a prospective cohort study design to enroll women 21 years of age or older at two study sites. They underwent two data collection sessions, baseline and follow-up after consensual sexual intercourse. Baseline genital-anal injury identification occurred with a standard forensic examination (direct visualization, nuclear staining with toluidine blue contrast, and colposcopy examination) and measurements of other variables (skin color, skin viscoelasticity, skin hydration, age, smoking history, body mass index [BMI], sun exposure, and health status). Participants were then asked to have consensual sexual intercourse with a male partner of their choice and to return for a second forensic examination for injury detection. Genital-anal injury was regressed on skin color, skin viscoelasticity, skin hydration, age, smoking history, BMI, sun exposure, and health status. FINDINGS: We enrolled 341 participants, 88 non-Hispanic White (25.8%), 54 non-Hispanic Black (15.8%), 190 Hispanic/Latina (55.7), and 9 Other Identities (2.6%). At baseline the genital-anal injury prevalence was 57.77% and at follow-up after consensual sexual intercourse, injury prevalence was 72.73%. External genital injury prevalence was associated with increased L* (lightness) values (Adjusted Odds Ratio [AOR] = 1.98, 95% Confidence Interval [CI] = 1.03, 4.04) and decreased skin elasticity (AOR = 0.96, 95% CI = 0.93, 0.99) at baseline. Increased skin hydration was associated with a significantly higher frequency of external, internal, anal, and total genital-anal injuries (Adjusted Rate Ratio [ARR] > 1.27) at follow-up. Also at the follow-up examination, Hispanic/Latina participants had significantly lower external genital and total genital-anal injury prevalence and frequency as compared to non-Hispanic White participants (AOR < 0.40). CONCLUSIONS: Our findings provide qualified support for the importance of skin color during the forensic examination. Women with lighter skin tones may have skin that is more easily injured than women with darker tones. In contrast, external genital injuries may be more easily identified in women with light as compared to dark skin, a situation that is important in both the health care and criminal justice systems. Additionally, women with decreased viscoelasticity and increased hydration may be more easily injured. These findings support the need to develop forensic procedures that are effective in people across the range of skin colors and to interpret forensic findings considering the innate properties of the skin.

Assessment of Predictors of Sun Sensitivity as Defined by Fitzpatrick Skin Phototype in an Ecuadorian Population and Its Correlation with Skin Damage.

BACKGROUND: The Fitzpatrick skin phototype scale (FSPTS) is a widely used instrument to assess skin type. METHODS: A cross-sectional survey collected responses from 254 subjects from Quito regarding self-reported FSPTS, gender, age, education, and tobacco and alcohol consumption. Univariate and multivariate logistic regression analyses were performed to determine if ethnicity, hair color, and eye color significantly predict FSPTS. In addition, we studied the correlation between FSPTS and the SCINEXA scale with Pearson's correlation coefficient. RESULTS: Ethnicity, eye color, and hair color are significant independent predictors of FSPTS (p < 0.0001). CONCLUSIONS: Patient self-reported race and pigmentary phenotypes are inaccurate predictors of sun sensitivity as defined by Fitzpatrick skin phototype. Our study does not fully represent the population of the country. There are limitations to using patient-reported race and appearance in predicting individual sunburn risk.

Cosmetic Laser Procedures in Latin Skin

Hispanics/Latinos are one of the fastest growing segments in the skin of color population in the United States. Utilization of lasers especially in people with skin of color requires a thorough understanding of laser physics and laser tissue interactions. In this article, we will outline the different lasers used in our practice based on each chromophore. Pretreatment recommendations as well as management of complications will also be shortly discussed. Our goal is for the readers to grasp the importance of proper device selection, understand the concept of selective photothermolysis, and the various treatment parameters required for optimal safety and efficacy. J Drugs Dermatol. 2019;18(3 Suppl):s127-131.

Skin Color and Social Mobility: Evidence From Mexico.

In many Latin American countries, census data on race and skin color are scarce or nonexistent. In this study, we contribute to understanding how skin color affects intergenerational social mobility in Mexico. Using a novel data set, we provide evidence of profound social stratification by skin color, even after controlling for specific individual characteristics that previous work has not been able to include, such as individual cognitive and noncognitive abilities, parental education and wealth, and measures of stress and parenting style in the home of origin. Results indicate that people in the lightest skin color category have an average of 1.4 additional years of schooling and 53 % more in hourly earnings than their darkest-skinned counterparts. Social mobility is also related to skin color. Individuals in the darkest category are 20 percentile ranks lower in the current wealth distribution than those in the lightest category, conditional on parental wealth. In addition, results of a quantile regression indicate that the darkest group shows higher downward mobility.

BMI Trajectories in Adulthood: The Intersection of Skin Color, Gender, and Age among African Americans.

This study addresses three research questions critical to understanding if and how skin color shapes health among African Americans: (1) Does skin color predict trajectories of body mass index (BMI) among African Americans across ages 32 to 55? (2) To what extent is this relationship contingent on gender? (3) Do sociodemographic, psychosocial, and behavioral factors explain the skin color-BMI relationship? Using data from the Coronary Artery Risk Development in Young Adults Study and growth curve models, results indicate that dark-skinned women have the highest BMI across adulthood compared to all other skin color-gender groups. BMI differences between dark- and lighter-skinned women remain stable from ages 32 to 55. Among men, a BMI disadvantage emerges and widens between light- and dark-skinned men and their medium-skinned counterparts. Observed sociodemographic characteristics, stressors, and health behaviors do not explain these associations. Overall, findings suggest that skin color- and gender-specific experiences likely play an important role in generating BMI inequality.

Comparison of radiation dermatitis between hypofractionated and conventionally fractionated postoperative radiotherapy: objective, longitudinal assessment of skin color.

This study aimed to quantitatively compare radiation dermatitis due to hypofractionated (Hypo) and conventionally fractionated (Conv) external-beam radiotherapy in patients who underwent postoperative radiotherapy after breast-conserving surgery. Skin color changes, in terms of L* (brightness, white-black), a* (red-green), and b* (yellow-blue) values, due to external-beam radiotherapy were examined at alternate fractions using an objective method. Twenty-six patients were included in the Hypo group (42.56 Gy/16 fractions) and 46 in the Conv group (50 Gy/25 fractions). Radiotherapy decreased the L* value (darker) and increased the a* value (redder) gradually. These color alterations progressed linearly according to elapsed fractions and were similar between Hypo and Conv per fraction. The Hypo group showed significantly milder alterations in L* and a* values than the Conv group. The maximal dosage was significantly correlated to alterations in L* and a* values. Common Terminology Criteria for Adverse Events v4 assessment did not show a statistically significant difference between the Hypo (Grade 0:1:2 = 2:24:1) and Conv (1:39:6, p = 0.25) groups. The results of our objective analysis revealed that patients undergoing Hypo show milder color alteration than those undergoing Conv and that the maximal dosage is a useful predicator of color alteration.

The influences of genes, the environment, and social factors on the evolution of skin color diversity in India.

OBJECTIVES: Skin color is a highly visible and variable trait across human populations. It is not yet clear how evolutionary forces interact to generate phenotypic diversity. Here, we sought to unravel through an integrative framework the role played by three factors-demography and migration, sexual selection, and natural selection-in driving skin color diversity in India. METHODS: Skin reflectance data were collected from 10 diverse socio-cultural populations along the latitudinal expanse of India, including both sexes. We first looked at how skin color varies within and between these populations. Second, we compared patterns of sexual dimorphism in skin color. Third, we studied the influence of ultraviolet radiation on skin color throughout India. Finally, we attempted to disentangle the interactions between these factors in the context of available genetic data. RESULTS: We found that the relative importance of these forces varied between populations. Social factors and population structure have played a stronger role than natural selection in shaping skin color diversity across India. Phenotypic overprinting resulted from additional genetic mutations overriding the skin lightening effect of variants such as the SLC24A5 rs1426654-A allele in some populations, in the context of the variable influence of sexual selection. Furthermore, specific genotypes are not associated reliably with specific skin color phenotypes. This result has relevance for DNA forensics and ancient DNA research. CONCLUSIONS: India is a crucible of macro- and micro-evolutionary forces, and the complex interactions of physical and social forces are visible in the patterns of skin color seen today in the country.

Skin colour assessment of replanted fingers in digital images and its reliability for the incorporation of images in nursing progress notes.

AIMS AND OBJECTIVES: To determine whether nurses can accurately assess the skin colour of replanted fingers displayed as digital images on a computer screen. BACKGROUND: Colour measurement and clinical diagnostic methods for medical digital images have been studied, but reproducing skin colour on a computer screen remains difficult. DESIGN: The inter-rater reliability of skin colour assessment scores was evaluated. In May 2014, 21 nurses who worked on a trauma ward in Japan participated in testing. METHODS: Six digital images with different skin colours were used. Colours were scored from both digital images and direct patient's observation. The score from a digital image was defined as the test score, and its difference from the direct assessment score as the difference score. Intraclass correlation coefficients were calculated. Nurses' opinions were classified and summarised. RESULTS: The intraclass correlation coefficients for the test scores were fair. Although the intraclass correlation coefficients for the difference scores were poor, they improved to good when three images that might have contributed to poor reliability were excluded. Most nurses stated that it is difficult to assess skin colour in digital images; they did not think it could be a substitute for direct visual assessment. However, most nurses were in favour of including images in nursing progress notes. DISCUSSION: Although the inter-rater reliability was fairly high, the reliability of colour reproduction in digital images as indicated by the difference scores was poor. Nevertheless, nurses expect the incorporation of digital images in nursing progress notes to be useful. This gap between the reliability of digital colour reproduction and nurses' expectations towards it must be addressed. CONCLUSIONS: High inter-rater reliability for digital images in nursing progress notes was not observed. Assessments of future improvements in colour reproduction technologies are required. RELEVANCE TO CLINICAL PRACTICE: Further digitisation and visualisation of nursing records might pose challenges.

Analysis of the influence of collagen fibres in the dermis on skin optical reflectance by Monte Carlo simulation in a nine-layered skin model.

BACKGROUND: Collagen fibres in the dermis play an important structural role in the skin. Age-related changes to these fibres cause wrinkles and slackness of facial skin. However, it is not clear how dermal collagen fibres affect skin colour. The purpose of this study was to clarify the influence of altered collagen fibres on skin colour, using both experimental measurement of fibre density and Monte Carlo simulations in an optical model of skin. METHODS: Reflection spectra were measured from the cheeks of 12 Japanese women (22-65 years old) by spectral colorimeter. Two-dimensional autocorrelation functions were calculated from second harmonics generation (SHG) images acquired from the same locations and used to calculate collagen density indices. Monte Carlo simulations of light reflectance by skin were performed using a nine-layered model that precisely imitates skin structure. The relationship between dermal collagen fibre density and skin reflection spectra was analysed. RESULTS: A positive correlation was found between collagen density and skin brightness, as measured by the colour value, L* (using the L*a*b* colour space). In addition, collagen density showed a strong inverse correlation with age and with the optical absorption of dermis. The Monte Carlo simulations showed that the reflection spectrum of skin changes when the scattering coefficient of the dermis is altered. These changes were the same for simulated and experimentally measured reflection spectra. CONCLUSION: When collagen fibre density in the upper dermis is decreased with age, skin colour becomes less bright because light scattering in the skin is decreased.

Development of a quantitative assessment method of pigmentary skin disease using ultraviolet optical imaging.

BACKGROUND/PURPOSE: The visual scoring method has been used as a subjective evaluation of pigmentary skin disorders. Severity of pigmentary skin disease, especially melasma, is evaluated using a visual scoring method, the MASI (melasma area severity index). This study differentiates between epidermal and dermal pigmented disease. The study was undertaken to determine methods to quantitatively measure the severity of pigmentary skin disorders under ultraviolet illumination. METHODS: The optical imaging system consists of illumination (white LED, UV-A lamp) and image acquisition (DSLR camera, air cooling CMOS CCD camera). Each camera is equipped with a polarizing filter to remove glare. To analyze images of visible and UV light, images are divided into frontal, cheek, and chin regions of melasma patients. Each image must undergo image processing. To reduce the curvature error in facial contours, a gradient mask is used. RESULTS: The new method of segmentation of front and lateral facial images is more objective for face-area-measurement than the MASI score. Image analysis of darkness and homogeneity is adequate to quantify the conventional MASI score. Under visible light, active lesion margins appear in both epidermal and dermal melanin, whereas melanin is found in the epidermis under UV light. CONCLUSION: This study objectively analyzes severity of melasma and attempts to develop new methods of image analysis with ultraviolet optical imaging equipment. Based on the results of this study, our optical imaging system could be used as a valuable tool to assess the severity of pigmentary skin disease.

Updating the diagnosis, classification and assessment of rosacea: recommendations from the global ROSacea COnsensus (ROSCO) panel.

BACKGROUND: Rosacea is currently diagnosed by consensus-defined primary and secondary features and managed by subtype. However, individual features (phenotypes) can span multiple subtypes, which has implications for clinical practice and research. Adopting a phenotype-led approach may facilitate patient-centred management. OBJECTIVES: To advance clinical practice by obtaining international consensus to establish a phenotype-led rosacea diagnosis and classification scheme with global representation. METHODS: Seventeen dermatologists and three ophthalmologists used a modified Delphi approach to reach consensus on statements pertaining to critical aspects of rosacea diagnosis, classification and severity evaluation. All voting was electronic and blinded. RESULTS: Consensus was achieved for transitioning to a phenotype-based approach to rosacea diagnosis and classification. The following two features were independently considered diagnostic for rosacea: (i) persistent, centrofacial erythema associated with periodic intensification; and (ii) phymatous changes. Flushing, telangiectasia, inflammatory lesions and ocular manifestations were not considered to be individually diagnostic. The panel reached agreement on dimensions for phenotype severity measures and established the importance of assessing the patient burden of rosacea. CONCLUSIONS: The panel recommended an approach for diagnosis and classification of rosacea based on disease phenotype.

A Split-Face Assessment of the Synergistic Potential of Sequential Q-Switched Nd:YAG Laser and 1565 nm Fractional Nonablative Laser Treatment for Facial Rejuvenation in Fitzpatrick Skin Type II-V Patients.

Recent appreciation of the multifactorial pathophysiology of skin aging has led to increased use of parallel treatment regimens. This prospective, split-face, randomized study assessed the safety and efficacy of same-day sequential Q-switched Nd:YAG laser and 1565 nm non-ablative fractional laser (SST) facial rejuvenation treatment in comparison to fractional non-ablative laser (NAFL) treatment only. Seventeen patients underwent three treatment sessions, conducted at 4-6-week intervals, in which SST treatment was delivered on a randomly selected side of the face followed by NAFL treatment on the contralateral side immediately thereafter. Immediate skin responses were assessed within 30 minutes of treatment, while wrinkle/elastosis scores, and skin tone and texture were evaluated 1, 3, and 6 months following the final treatment session. While SST and NAFL proved equally safe, SST was associated with signi cantly lower pain scores in all three treatment sessions. Both treatment regimens yielded signi cant improvements in wrinkle/elastosis scores, which were maintained throughout the 6 months of follow up. Physician-evaluated skin tone and patient ratings of skin texture and overall improvement of the SST-treated side were consistently higher than the contralateral NAFL-treated side. Histological analysis suggested a broader effect, alongside sparing of the outermost epidermal layer with the SST versus NAFL treatment. Although the SST regimen failed to demonstrate statistically signi cant clinical superiority over the NAFL regimen, the significantly lower pain levels, consistently higher physician and patient ratings following SST may justify its regular use as a skin rejuvenation technique. J Drugs Dermatol. 2016;15(11):1335-1342..

Development and Clinical Assessment of a Comprehensive Product for Pigmentation Control in Multiple Ethnic Populations.

BACKGROUND: Pigmentary changes in people of different ethnic origins are controlled by slight variations in key biological pathways leading to different outcomes from the same treatment. It is important to develop and test products for desired outcomes in varying ethnic populations. OBJECTIVES: To develop a comprehensive product (LYT2) that affects all major biological pathways controlling pigmentation and test for clinical efficacy and safety in different ethnic populations. METHODS: A thorough analysis of biological pathways was used to identify ingredient combinations for LYT2 that provided optimal melanin reduction in a 3-D skin model. Expression of four key genes for melanogenesis, TYR, TYRP-1, DCT, and MITF was analyzed by qPCR. Clinical study was conducted to compare the efficacy and tolerability of LYT2 against 4% hydroquinone (HQ). RESULTS: Average melanin suppression by LYT2 in 7 independent experiments was 45%. All four key genes show significant down- regulation of expression. LYT2 provided statistically significant reductions in mean overall hyperpigmentation grades as early as week 2 compared to baseline, with continued significant improvements through week 12 in all ethnic groups tested. CONCLUSION: We have successfully combined management of 6 categories of pathways related to melanogenesis: melanocyte activation, melanosome development, melanin production, melanin distribution, keratinocyte turnover, and barrier function to create a comprehensive HQ-free product. The outcome clearly shows greater pigmentation control with LYT2 compared to other HQ-free products in skin tissue models and earlier control in clinical studies compared to 4% HQ. Clinical study shows pigmentation control benefits of LYT2 in people of Caucasian, Hispanic, and African ethnic origins. J Drugs Dermatol. 2016;15(12):1562-1570.