The relationship of skin color, UVB-induced erythema, and melanogenesis

The relationship between skin color, delayed erythema, and delayed tanning (DT) elicited by a single exposure of UVB was investigated. Both constitutive and facultative pigmentation were determined by skin reflectance using a melanometer. Skin reflectance using visible light was well correlated to the minimal immediate pigment darkening dose elicited by UVA irradiation, which may relate to epidermal melanin content, a determinant of skin color. Minimal erythemal dose (MED) was well correlated to skin color, but there was less correlation between minimal melanogenic dose and skin color or the MED, since melanogenesis is controlled by genetic factors. DT also correlated to the dose of UVB in terms of MED. A coefficient of the regression line of DT may suggest the tanning capacity of skin. The possibility of detecting mild photosensitivity in individuals from a regression line of the MED on skin color is suggested.     

Correlation Between Skin Color Evaluation by Skin Color Scale Chart and Narrowband Reflectance Spectrophotometer

Context:

Various methods are available for the evaluation of skin color. A skin color scale chart is a convenient and inexpensive tool. However, the correlation between a skin color scale chart and objective measurement has not been evaluated.

Aims:

To assess the correlation between skin color evaluation done by a skin color scale chart (Felix von Luschan skin color chart) and a narrowband reflectance spectrophotometer (Mexameter MX18).

Materials and Methods:

The participants were evaluated for skin color by using the Felix von Luschan skin color chart (range 1-36) and a narrowband reflectance spectrophotometer (Mexameter MX18) in which the results of the measurements were expressed as Erythema (E) and Melanin (M) indices. Skin color was measured on four different anatomical skin sites from each participant on the medial aspect of the volar and the dorsal regions of both forearms. Results: A total of 208 records from 52 participants were established. The majority of participants (19.2%) were rated with the skin color scale at the number 16 (range 14-33). The mean M plus E, M, and E indices were 498.9 ± 143.9, 230.4 ± 74.4, and 268.5 ± 73.2, respectively. The correlation coefficient between the number on the skin color scale and each index: M plus E, M, and E indices were 0.90, 0.90, and 0.86, respectively, with a statistical significance of P < 0.001.

Conclusions:

Skin color evaluation using a skin color scale chart has shown a high correlation with skin color evaluation done by the narrowband reflectance spectrophotometer.     

621例上海女性最小红斑量测定

目的 通过测定上海成年女性的最小红斑量,探讨并分析年龄和皮肤颜色对皮肤光敏性的影响程度.方法 测定上海某社区内621名健康女性的最小红斑量值,并选择窄谱分光光度仪对志愿者皮肤颜色进行测定,观察皮肤颜色与最小红斑量的相关性.结果 31～40岁女性MED中位数为39.04s,而41～50岁组和51～60岁组MED中位数均为24.99 s;31～40岁组的MI值和EI值与MED值相关系数分别为0.366和0.315,而年龄大的组别中其相关系数相对较小.结论 随着年龄增长,皮肤对紫外线敏感性增强,皮肤颜色与最小红斑量密切相关.

Abstract：

Objective To determinate the minimal erythema dose (MED) of adult females and to analyze the influence of age and skin color on skin photosensitivity. Methods MED was determined in 621healthy adult females in Shanghai region, and narrow-band spectrophotometer was used to detect the skin color of these subjects. The correlation between skin color and MED was assessed. Results The median MED was 39.04 in testees aged between 31 and 40 years, 24.99 in those aged between 41 and 50 years and in those between 51 and 60 years. The correlation indice were 0.366 and 0.315 between MI and MED and between EI and MED respectively in testees aged between 31 and 40 years, relatively higher than those in testees over 40 years of age. Conclusions The sensitivity of skin to ultraviolet rays increases with age, and there is a close relationship between the skin color and MED.     

Characteristics of self-estimated enhanced skin susceptibility.

A considerable number of people complain about enhanced skin sensitivity. The aim of this study was to investigate the characteristics of subjective statements and objective measurable parameters in subjects with self-estimated enhanced skin susceptibility. Four-hundred-and-twenty volunteers completed a questionnaire form with a self-estimation of skin susceptibility, possible triggering factors and other skin problems. In addition, basal values of transepidermal water loss, cutaneous blood flow and skin hydration were measured. One-hundred and fifty-two volunteers were also patch-tested with sodium lauryl sulphate 0.5% on the forearm and evaluated by bioengineering methods. We found no correlation between self-estimated skin susceptibility and bioengineering values, neither basal nor after sodium lauryl sulphate testing. These findings, along with interpretation of the questionnaire form, suggest that self-estimated enhanced skin susceptibility is a subjective problem mostly reported by women and of all ages.     

Characterization of cutaneous photosensitivity in healthy volunteers receiving talaporfin sodium

Purpose: Historically, cutaneous photosensitivity has been the most common side effect of treatment with light‐activated drugs. Talaporfin sodium is a water soluble photosensitizer in commercial use and clinical development that is cleared from the body relatively rapidly. This trial was conducted to determine the period of skin photosensitivity in healthy subjects given talaporfin sodium and to determine the correlation between photosensitivity and plasma levels of talaporfin sodium. Methods: Twenty healthy volunteers were dosed with 0.25–1.0 mg/kg talaporfin sodium and exposed at successive timepoints to a solar simulator applied to a small patch of skin on the back. Photosensitivity was assessed at these sites 24 h later. Duration of photosensitivity and correlation with plasma drug concentration were analyzed. Results: Skin reactions were generally mild and were classified most commonly as asymptomatic erythema. Photosensitivity subsided in each subject between 1 and 3 weeks after dosing. Subjects no longer exhibited photosensitivity at plasma drug levels between 600 and 2900 ng/ml in each subject. Two subjects in the lowest dose group did not exhibit photosensitivity despite plasma drug levels as high as 4000 ng/ml. Conclusions: These results indicate that a clinically effective dose of talaporfin sodium was well‐tolerated and that cutaneous photosensitivity was mild and resolved relatively rapidly.     

An evaluation of the relationship between 'atopic skin' and skin irritability in metalworker trainees

Skin hyperirritability to irritants as well as atopy are considered to be predisposing factors for contact dermatitis. The aim of the study was to evaluate whether these predictive factors are independent or whether they are so closely related that one could possibly replace the oilier. 205 metalworker trainees underwent skill examination for skin atopy, including standardised questionnaire, clinical examination of the skin and a series of skin irritability tests. These tests included measurements of transepidermal water loss (TEWL) before and after irritation with 3 different irritants: sodium lauryl sulfate (SLS), dimethylsulfoxide (DMSO) and sodium hydroxide (NaOH). The results of the linear regression analysis demonstrate that skin atopy is not associated with increased skin irritability, as assessed by the irritability testing methods presented.     

Acute irritant contact dermatitis: recovery time in man

Our understanding of the details of the recovery time of acute irritant contact dermatitis (ICD) is limited. We examined skin reactivity to a model surfactant, sodium lauryl sulfate (SLS). on previous acute ICD and normal sites over time with visual grading and noninvasive instruments. Acute ICD was induced on the upper arms of 18 volunteers (aged 30 to 51 years) by occluded application of 1% SLS for 24 h. Previous ICD and normal sites were provoked by occluded application of 2% or 7.5% SLS 30 min daily 4 consecutive days. Skin reactivity was assessed daily by visual erythema scoring (VES), transepidermal water loss (TEWL), skin color reflectance (SCR) and electrical capacitance (EC). Skin function of previous ICD sites assessed, by VES, TEWL. SCR, and EC did not normalize until 2 weeks later: all parameters of previous ICD returned to normal after 3 weeks. While skin reactivity to 2% und 7.5% SLS showed no differences between previous ICD and normal sites at 4 weeks, differences of irritant reactivity especially 7,5% SLS between previous ICD and normal sites were significant at 3 weeks post-provocation. Our results demonstrate that irritation evaluated with irritant provocation was long-lasting, even though skin functional parameters assessed by various bioengineering instruments returned to normal. Complete recovery of skin function including irritability after acute ICD induced by 1% SLS was achieved approximately 4 weeks later. The date were generated with a model surfactant: it remains to be determined whether similar responses will be noted with chemicals of different physicochemical properties.     

Water content and thickness of the stratum corneum contribute to skin surface morphology

Abstract Skin surface morphology has long been recognized as reflecting skin pathology. In the present study, we evaluated skin surface morphology using hairless mice under contrasting conditions of humidity. The skin surface microrelief was recorded with opaque quick-drying silicone rubber, and examined under a microscope. A binary image was produced by density slicing. Within 3 days of exposure to dry conditions, skin roughness was significantly increased. The skin roughness was partially mitigated by topical application of an aqueous solution of glycerol or hydration by immersion in water. A significant correlation between skin roughness and stratum corneum thickness was also observed. These results suggest that skin surface morphology is associated with both water content and thickness of the stratum corneum. Received: 29 November 1999 / Received: 1 March 2000 / Accepted: 22 March 2000     

Lack of correlation between minimal erythema dose and skin phototype in a colombian scholar population

Background: Sun exposure and skin phototype are the most relevant risk factors for skin cancer. Colombia has high levels of ultraviolet radiation during the whole year, therefore, both, high UVI's and outdoor worker's daily activities, in our country are very important risk factors for the development of cutaneous cancer. To date no study has evaluated the usefulness of Fitzpatrick's skin phototype classification in Colombians and its correlation with the minimal erythema dose (MED) and constitutional skin color. Such information is gaining importance in other nations due to the fact that several country's population is becoming more ethnically diverse. Objectives: To determine the skin phototype, accumulated sun exposure, sun protection behavior, MED and phenotype in a Colombian school population. Methods: Last year high school students from the western Antioquia were invited to participate by phone and letter through their respective school directors. A self‐questionnaire was handled to each student. A representative sample of the universe was selected for a medical examination by a dermatologist in order to validate the results of the self‐questionnaire. The constitutional skin color was determined with the chromameter CR 300 Minolta^®. The MED was defined as the minimal dose of UVB being able to induce erythema 24 h later. Results: Eight schools of the area agreed to participate in the study, and a total of 911 students (58% girls and 42% boys) filled‐out the self‐questionnaire. Sun exposure in the majority of individuals was in a level between moderate and very high. Ninety percent of students do not use any sun protection device or cream. Only a 50% of concordance between self‐assessed skin phototype vs. medical skin phototype was found, and the highest concordance corresponded to skin phototype II (82%). There was a marked difference in skin photosensitivity of Colombians compared with reports in Caucasians. We observed a marked overlapping in MED's and L^* values in phototypes II and III. Conclusions: The Fitzpatrick's classification was not useful in Hispanic populations such as ours. Therefore, a new skin‐phototype classification system is required. In our population the constitutional color was a good predictor of the MED but it did not correlate with skin phototype. The self‐assessed questionnaire method was not useful to determine skin cancer risk in our population. The majority of this population has light skin phototypes and is highly exposed to solar UV radiation without proper protection.     

Effect of cyproterone acetate on skin surface lipids.

Skin surface lipids in female patients with acne were examined before and after treatment with the oral contraceptive SH 209 AB (2 mg cyproterone acetate and 0.05 mg ethinyl estradiol) by direct extraction with petrol ether and photometrical determination. A significant reduction in the skin surface lipids was seen, together with a remarkable alleviation of the disease.     

Skin color of Koreans: statistical evaluation of affecting factors

BACKGROUND: The L*a*b* three-dimensional coordinate system is the most popular system used to measure skin color. The purpose of this study was to collect standard quantified data on Korean skin color using a chromameter CR-300, and to investigate the relationships among skin color and the general and individual factors that affect it. METHODS: The 600 subjects used in this study were selected using a three-stage proportionate stratified and quota sampling method. We examined the color of 12 body parts of each subject and calculated the E* value (total color difference between two objects). This study also analyzed factors that may affect skin color. RESULTS: The average L*a*b* values for the 12 body parts were 61.7462, 9.5618 and 17.0778, respectively. The site of lightest skin was the medial arm (L=63.9249), whereas the darkest was on the forehead (L=58.0044). Redness was highest on the cheek (a=11.8694) and lowest on the medial arm (a=8.1844). Skin color was lighter and more yellow in females than in males, whereas redness was higher in males. In the case of total color difference between two specific sites, the medial upper arm and forearm were the most similar (E=3.23), and the forehead and medial upper arm were the most different in color (E=7.99). CONCLUSION: The factors that significantly (P<0.01) influenced L* were sex, work place and sunbathing, factors that influenced a* were sex, work place and smoking; and the factors that influenced b* were sunbathing and age.     

Chemical and pharmacologic skin irritation in man

Attention is increasingly being focused on the relationship of dissociation constant (pKa) of chemicals and skin irritation presumably caused by pH effects at epidermal levels. Human skin studies of irritation have utilized both subjective visual-palpation scores and reflectance spectroscopy (RS) or laser Doppler velocimetry (LDV) respectively. Several studies document that erythema determined subjectively and objectively correlates with the degree of skin irritancy, but others report lack of correlation between LDV and irritancy scored subjectively. In this study, pharmacological and chemical in vivo skin irritation was evaluated utilizing an improved reflectance spectrophotometer equipped with computerized data analysis. In 16 white females, a model for skin irritation was induced by a 24-h patch application of 4 basic chemicals, imipramine, norephedrine, nicotine and 8-aminoquinoline, with pKa'S ranging from 3.8 to 9.5. Skin pigmentation (melanin) and the relative amounts of oxygenized (arterial) and deoxygenized (venous) hemoglobin present in the erythematous skin were calculated. A clear increase in the hemoglobin content was observed in chemical and vehicle exposed sites. Although skin irritation is a complex phenomenon involving chemical and solution properties, percutaneous absorption and the biological drug response, high pKa (p greater than 0.01) was predictive of acute skin irritation in man using computerized analysis of reflectance spectroscopy. A high correlation between visual score and RS was found (r = 0.91).     

Skin surface lipids in HIV sero-positive and HIV sero-negative patients affected with seborrheic dermatitis.

Skin surface lipids of patients affected with seborrheic dermatitis both HIV sero-negative (C group) and HIV sero-positive (B group) have been studied by capillary Gas chromatography-Mass spectrometry (GC-MS) in comparison with normal age matched controls (A group) to determine whether, among the three groups of individuals, there were qualitative and quantitative changes in lipid class composition and in the fatty acid and alcohol components of lipid fractions. With regard to percent composition of skin surface lipid fractions, no significant differences were found between HIV sero-positive and HIV sero-negative patients with seborrheic dermatitis. The observed significant reduction of total lipids (micrograms/sq cm) in the sites affected with the disease in comparison with controls was associated with a slight but significant decrease of squalene (P less than 0.05) and with a corresponding increase of cholesterol and cholesterol esters (P less than 0.05). These abnormalities in lipid fractions and total lipids were not observed in the uninvolved skin of subjects with seborrheic dermatitis. Fatty acid and alcohol patterns of skin lipid fractions were not significantly different among the three groups of individuals.     

Effects of single application of a moisturizer: evaporation of emulsion water, skin surface temperature, electrical conductance, electrical capacitance, and skin surface (emulsion) lipids

Effects of single application of an oil in water emulsion were studied on the forearm skin of 12 healthy volunteers. Five different non-invasive methods were used. Values were followed for 360 min after application of the emulsion, with the contralateral forearm as untreated control. The evaporation of emulsion water from the skin surface immediately rose to high values, but within 15 min returned to the original level. A parallel initial increase in conductance was observed; however, this was followed by a slightly increased level throughout the 360 min study. Electrical capacitance was also slightly increased throughout the study. Skin surface lipids, dominated by emulsion lipids, were increased, with high values for at least 120 min, followed by a gradual decline toward normal. Single application of emulsion is characterized by an initial evaporation phase, with evaporation of emulsion water, which lasts less than 15 min, followed by a lipidization phase, which lasts at least 360 min, dominated by the oil-constituent of the emulsion undergoing epidermal absorption. During the lipidization phase, epidermal hydration parameters are slightly but consistently improved.     

Response to thermal stimuli in skin pretreated with sodium lauryl sulfate

Skin irritation is mostly a multifactorial process. Competitive effects of different chemical irritants are well known. This study investigates the influence of a thermal stimulus on skin pre-irritated with sodium lauryl sulfate (SLS). Seventy-seven volunteers were patch-tested with SLS 0.25% and 0.5% for 48 h. Water served as control. Skin reaction was evaluated by measurement of transepidermal water loss, skin blood flow and skin color. After measurement, a thermal stimulus was applied on the test area. The increase in skin blood flow was measured. There was a significant correlation between the degree of irritation and the increase in skin blood flow after thermal stimulus. Pre-irritated skin reacted to thermal stimulus with a shorter and sharper increase in skin blood flow. This increase was dependent on the SLS concentration. Hence, the thermally stimulated blood flow may be a model of non-chemical irritation and seems to be a relevant co-factor in the pathogenesis of irritant dermatitis.     

Cumulative irritation patch test of sanitary pads on sensitive skin

Background Tools are needed to assess the effects of various products on sensitive skin. Aim To investigate the cutaneous compatibility of various sanitary pads in people with self‐declared sensitive skin. Patients/methods Eight subjects, who considered their skin to be sensitive and who reported adverse skin responses to everyday products or clothing, were patch tested on the arm with two, low‐irritancy sanitary pads for four consecutive 24‐hour periods. Test products differed only in their surface covering. Sodium lauryl sulfate solution (0.1% w/v) and physiological saline served as standard irritant and nonirritant controls, respectively. Skin irritation (erythema) was graded after each 24‐hour period. Results No significant difference in skin erythema scores was observed between groups (scores on day 4: 1.06 ± 0.11 vs. 1.25 ± 0.13, on a five‐point scale, P < 0.05). The temporal development of cumulative irritation associated with the pads was comparable to that observed with the nonirritant control (a plateau in maximal group scores) and distinct from that of the irritant control (continuously rising scores). Conclusion Sanitary pads under investigation elicited negligible cumulative irritation in a four‐day patch test on subjects with self‐declared sensitive skin. The temporal pattern of cumulative response was consistent with the inherently low irritation potential of the products.     

Barrier recovery and influence of irritant stimuli in skin treated with a moisturizing cream

Moisturizers are used daily by many people to alleviate symptoms of clinically and subjectively dry skin. Recent studies suggest that certain ingredients in creams may accelerate the recovery of a disrupted barrier and decrease the skin susceptibility to irritant stimuli. In the present single-blind study, a moisturizing cream was tested for its influence both on barrier recovery in surfuctant-damaged skin and on the susceptibility of normal skin to exposure to the irritant sodium lauryl sulphate (SLS). Parameters measured were transepidermal water loss (TEWL) and skin corneometer values, indicating degree of hydration. Treatment of surfactant-damaged skin with the test cream for 14 days promoted barrier recovery, as observed as a decrease in TEWL. Skin corneometer values also normalized more rapidly during the treatment. In normal skin, use or the test cream significantly reduced TFWL after 14 days of treatment, and irritant reactions to SLS were, significantly decreased. Skin corneometer values increased after only 1 application and remained elevated after 14 days. In conclusion, the accelerated rate of recovery of surfactant-damaged skin and the lower degree of SLS-induced irritation in normal skin treated with the test cream may be of clinical relevance in attempts to reduce contact dermatitis due to irritant stimuli.     

Effect of skin pH for wrinkle formation on Asian: Korean,Vietnamese and Singaporean

Background Skin pH may be influenced by various factors, such as hydration of stratum corneum, rate of sebum excretion rate, transepidermal water loss (TEWL) and sweating in relation to skin ageing. Objective The aim of this study was to evaluate the correlation between skin pH and wrinkle formation that is directly related to ageing. In addition, we investigated the factors related to skin ageing by comparing the association between skin pH and other skin properties. Methods Three hundred volunteers were selected from three countries: Korea, Vietnam and Singapore. Hydration on the stratum corneum, the rate of sebum excretion rate, melanin index, TEWL and skin temperature on the cheek were measured in a controlled room, and wrinkle length and depth using replicas were compared with skin pH variation. Results The mean and standard deviation of skin surface pH among the three countries were 5.510 ± 0.625. The greatest gap of skin pH that revealed significant differences for skin properties was represented between the Koreans and the Vietnamese. For all three countries, skin hydration, melanin contents, wrinkle length, wrinkle depth and skin temperature were significantly correlated with skin pH. Factors related to skin moisturizing, such as skin hydration, sebum excretion rate and skin temperature, were negatively correlated with skin pH. Wrinkle length and depth decreased as skin pH became more acidic. Conclusions Skin properties displayed various values depending on skin pH. In particular, wrinkle formation significantly decreased as skin pH becomes more acidic. We conclude that skin pH is determined by skin properties, such as skin hydration, sebum excretion rate, melanin concentration, TEWL and skin temperature that affects wrinkle formation.     

Effects of ultraviolet A and B on the skin barrier: a functional, electron microscopic and lipid biochemical study.

To investigate the effects of ultraviolet A (UVA) and B (UVB) on the skin barrier, functional, electron microscopic and lipid biochemical studies were performed on normal and UV-irradiated skin of volunteers. Skin reactivity against primary irritants was evaluated using the alkali resistance test, the dimethylsulfoxide test and the sodium lauryl sulfate test. In all 3 irritation models, UVA- and UVB-irradiated areas were more resistant to damage than normal skin, indicating improvement of the barrier function after UV irradiation. In a second series of experiments, biopsies were taken and processed for electron microscopic evaluation of the stratum corneum. UVB significantly increased the horny cell layers; UVA did not alter the thickness of the stratum corneum. Finally, stratum corneum lipids were extracted in vivo and quantified after high-performance thin-layer chromatography. UVB and, to some extent, UVA exposure increased the amount of all stratum corneum lipids. This was also observed in all major ceramide subfractions.     

Enzyme immunoassay for secretory immunoglobulin A on skin surface and in sweat

Recently secretory IgA (S-IgA) was found to be secreted from the eccrine gland. By using a sandwich enzyme immunoassay, we measured the concentration of S-IgA 1) in sweat (sweat S-IgA) and 2) in the extract buffer obtained by pipetting++ on the skin (skin surface S-IgA). Skin surface hydration and skin surface lipid were measured at the sites where the samples of skin surface S-IgA were collected. (These measurements were taken immediately after the buffer was pipetted). The quantity of both sweat S-IgA and skin surface S-IgA differed according to the sites where they were collected. Sites in order of decreasing sweat S-IgA level: face, chest, forearm. Sites in order of decreasing skin surface S-IgA level: face, chest, palm, forearm, sole. (Skin surface S-IgA levels on palm and forearm were approximately equal). Although the amount of skin surface S-IgA was not related to the skin surface hydration, there was a significant correlation between skin surface S-IgA and skin surface lipid.