Quantitative Characterization and Study of the Relationship between Constitutive-Facultative Skin Color and Phototype in Caucasians

In this study constitutive and facultative colorimetric values were quantified to determine the physiologic changes in Caucasian skin color and to define the correlation between skin color and phototype assessed according to the Fitzpatrick method. Our population consisted of 401 subjects ranging in age from 24 to 28 years with similar life styles. Skin color was measured with a Minolta CR-200 colorimeter on the upper medial quarter of the buttock (constitutive color) and on the cheek (facultative color). Advanced multivariate statistical analysis allowed differentiation between constitutive and facultative skin color in relation to the phototype to be quantified. Moreover, Kullback divergence showed that the probability of correctly determining a subject's phototype is high when the variables of constitutive and facultative skin color are considered together. This interesting result makes it possible, in the future, to use colorimetric values of exposed and nonexposed skin, together with determination of Fitzpatrick phototype and of other phenotypic characters, to better predict cutaneous sun reactivity.     

Mapping the Distribution of Melanin Concentration in Different Fitzpatrick Skin Types Using Hyperspectral Imaging Technique

Measuring skin melanin concentration in order to assess skin phototype according to Fitzpatrick's classification is a constant research goal. In this study, a new approach for assessing skin melanin concentration based on hyperspectral imaging combined with an appropriate analytical model that exploits specific spectral bands to generate maps of melanin content distribution on different Fitzpatrick skin phototypes is presented. Hyperspectral images from the proximal inner side of the forearms of 51 young volunteers covering the first four classes of Fitzpatrick's phototypes were acquired using a hyperspectral imaging system. The images were analyzed using a modified Beer–Lambert law that segregates the contribution of melanin from the other constituents to the skin absorption spectrum. The performance of the model was evaluated using the coefficient of determination (r-squared). The results revealed that the approach proposed in this study generated accurate melanin concentration distribution maps that allowed a correct classification of skin phototype. In conclusion, the proposed approach for assessing skin melanin concentration proved to be very reliable for classifying skin phototypes, and, as it provides maps that are easily read, it has the advantage of a possible extension of its applications to other research concerning skin pigmentation.     

ULTRAVIOLET ERYTHEMA SENSITIVITY IN ANAMNESTIC (I-IV) and PHOTOTESTED (1–4) CAUCASIAN SKIN PHOTOTYPES: THE NEED FOR A NEW CLASSIFICATION SYSTEM

Abstract— The anamnestic skin phototypes (ASP) I-IV^1,2 of 21 Caucasian volunteers were compared with their phototested skin phototypes (PSP) using solar simulating, broadband UV radiation. The Commission Internationale de' éclairage (CIE)-weighted (i.e. erythemally effective) minimal erythema doses (MED) for solar simulating radiation varied from 20 mJ/cm² (PSP type 1) to 57 mJ/cm² (PSP type 4). In only 11 of 21 volunteers did the ASP (I-IV) and PSP (1–4) classifications coincide, and the MED values of the volunteers within the different ASP groups (I-IV) overlapped considerably. To compare the reactivity to erythematogenic radiation of different wavelengths, narrowband monochromator irradiations were performed at 298 nm, 310 nm and 330 nm. The CIE-weighted MED values at these wavelengths (20–80 mJ/cm²) corresponded well with those obtained in the broadband testing. Our results indicate that, with classification by interrogation, Caucasian skin can reliably be classified into only two subtypes, corresponding to Fitzpatrick phototypes I–III and phototype IV, respectively. A classification into four sensitivity types can be achieved by phototesting, only. We propose that the concept of ASP should be used with caution. The concept of PSP 1–4 should be favored.     

Urocanic Acid Concentration and Photoisomerization in Caucasian Skin Phototypes

Abstract— To investigate the relationship between erythemal sensitivity of the skin to U V radiation and epidermal urocanic acid (UCA) concentration, 45 healthy volunteers of anamnestic skin phototypes (ASP) I-IV were studied. In 16 of the subjects, we analyzed UCA photoisomerization after graded UVB exposures. The median and mean total UCA concentration in unirradiated skin was 22.4 and 35.3 nmol/cm², and no statistically significant difference in total UCA concentrations was detectable either between ASP I through II and III through IV or between the phototested skin type (PSP) groups 1 through 2 and 3 through 4. The relative amount of the cis -isomer varied between 3 and 35%, with median and mean values of 7 and 12%, respectively. No statistically significant difference in absolute or relative cis -UCA concentrations was detectable between ASP I through II and III through IV, but a significantly lower absolute ( P < 0.009) and relative ( P < 0.002) cis -UCA concentration in unirradiated skin was recorded in PSP groups 1 through 2, compared to types 3 through 4. In all tested subjects, an erythemally weighted dose of 1 mj/cm²sufficed to cause trans - to cis -UCA isomerization. When comparing photosensitive (skin phototype I) and phototolerant (phototypes III and IV) individuals, who were irradiated with a reference 5 mJ/cm²UV dose or with fractions of 0.1-1.0 of their individual minimal erythema dose values, no skin phototype-dependent difference in ability to photoisomerize was discernible.     

Diffuse Reflectance Spectroscopy as a Tool to Measure the Absorption Coefficient in Skin: South African Skin Phototypes

In any laser skin treatment, the optical properties (absorption and scattering coefficients) are important parameters. The melanin content of skin influences the absorption of light in the skin. The spread in the values of the absorption coefficients for the South African skin phototypes are not known. A diffuse reflectance probe consisting of a ring of six light delivery fibers and a central collecting fiber was used to measure the diffused reflected light from the arms of 30 volunteers with skin phototypes I–V (on the Fitzpatrick scale). The absorption coefficient was calculated from these measurements. This real‐time in vivo technique was used to determine the absorption coefficient of sun‐exposed and ‐protected areas on the arm. The range of typical absorption coefficients for the South African skin phototypes is reported. The values for the darker South African skin types were much higher than was previously reported for darker skin phototypes. In the analysis, the contributions of the eumelanin and pheomelanin were separated, which resulted in improved curve fitting for volunteers of southern Asian ethnicity without compromising the other groups.     

Relationship between vitamin D status and skin phototype in general adult population

A link between bone mineral density and skin color has been reported recently, and pigmentation has been shown to affect cutaneous vitamin D production. In the present study, we investigated the relationship between phototype, global self-assessed sun exposure, geographical location and vitamin D serum levels in 1191 French adults. When the factors were analyzed separately, individuals with lower phototypes as well as those with lower sun exposure showed significantly lower levels of vitamin D than those with darker phototypes or those with higher sun exposure. However, when factors were analyzed as a whole, the vitamin D status was no longer linked with the phototype, but with sun exposure and geographical location. Since phototypes and global self-assessments of sun exposure were positively linked, our data suggest that lower vitamin D levels in fair-skinned individuals are due to their sun exposure behavior.     

Determination of the minimal erythema dose and colorimetric measurements as indicators of skin sensitivity to UV-B radiation

There is a strong relation between chronic UV-B-induced sunburns and the development of skin cancer. Therefore, it is important to obtain a method that can be reproduced easily to detect individuals with similar skin color but different sensitiveness to sun exposure. The study evaluated 193 healthy volunteers (68% women; the average age was 38 years). They were divided into six groups of at least 30 subjects, according to skin type. The minimal erythema dose (MED) was assessed in two non-sun-exposed areas (thorax-infra-axillary area and on the buttocks), using a UV-B source (0.5 mW/cm2), with openings of 1 cm2, in increasing doses. The same areas were evaluated with a Minolta CR 300 Chromameter (L*a*b* system). The MED values ranged from 13 to 156 mJ/cm2; the coordinate L* (brightness) ranged from 75.96 to 30.15. The correlation between the MED and the brightness was negative in both areas (Pearson's correlation r = -0.91, P < 0.05). Color measurements, especially brightness, can be used to quickly assess skin sensibility. Considering the MED, there is a substantial overlapping of adjacent phototypes, but they could be separated into two groups: more sensitive individuals (Types I, II, III and IV) and less sensitive ones (Types V and VI).     

Melanin content of cultured human melanocytes and UV-induced cytotoxicity

Cultured melanocytes originating from persons with different skin phototypes were utilized for measurement of endonuclease sensitive sites induced by UVB and the determination of cell survival after UVA or UVB irradiation. During culture, the melanocytes largely maintained their phenotypic characteristics according to their original skin phototype. Total melanin concentrations were 4.9 times higher in the darker skin phototype (IV-VI) melanocytes when compared to the cells from lighter skin phototypes (I-III). Also phaeomelanin contents were higher (2.5 times) in the skin phototype (IV-VI) melanocytes which implies that the cells from light skin types contain less melanin, but a relatively high proportion of phaeomelanin. After UVB irradiation a stronger induction of endonuclease sensitive sites was found for melanocytes with a lower level of total melanin and a high content of pheomelanin. By measuring the clone forming ability in different melanocyte cultures after UVB irradiation, significant better survival was found in case of the cells with the higher melanin content. Despite the large variations in melanin content, no significant difference in survival after UVA irradiation could be demonstrated in this way. Our results suggest a protective effect of melanin for UVB and indicate the importance of the measurements of melanin content and composition when different parameters of UV-induced damage are studied in melanin producing cells.     

The Arg160Trp allele of melanocortin-1 receptor gene might protect against vitiligo

Melanocortin-1 receptor (MC1R) and agouti signaling protein (ASIP) play pivotal roles in the regulation of human pigmentation. We aimed to study whether single nucleotide polymorphisms (SNPs) of the MC1R and ASIP genes contribute to the pathogenesis of the polygenic pigment skin disorder, vitiligo. The PCR-amplified, full-length MC1R gene was studied with sequence analysis, and the 3' untranslated region (3' UTR) SNP of ASIP was detected using restriction fragment length polymorphism. The allele frequency of the ASIP SNP did not show any difference between the skin type, hair color and eye color-matched 97 vitiligo patients and the 59 healthy control individuals. As one of the MC1R polymorphisms showed significantly higher incidence among fair-skinned individuals (Fitzpatrick I+II, n=140) than among dark-skinned individuals (Fitzpatrick III+IV, n=90), both vitiligo patients and controls were divided into two groups and the frequency of the MC1R alleles was studied separately in fair-skinned and dark-skinned subgroups of diseased and healthy groups. C478T, one of the MC1R SNPs studied in 108 fair-skinned vitiligo patients and in 70 fair-skinned healthy control individuals, showed a significant difference (P=0.0262, odds ratio [95% confidence interval]=3.6 [0.0046-0.1003]) in allele frequency between the two groups: the allele frequency was higher in the control group, suggesting protection against vitiligo. Computer prediction of antigenicity has revealed that the Arg160Trp amino acid change caused by this SNP results in a decrease in antigenicity of the affected peptide epitope.     

ACTION SPECTRUM FOR ERYTHEMA IN HUMANS INVESTIGATED WITH DYE LASERS

Abstract— Erythema reactions of human skin were reevaluated with improved experimental methods: a tunable, highly monochromatic irradiation source as well as an instrumental measurement of skin reactions were used. The irradiation system consisted of an excimer laser pumped dye laser and a U V fiber optic system. The skin color after irradiation was determined with a colorimeter in the three-dimensional norm system of the Commission Internationale d'Eclairage (CIE). The wavelength dependence for delayed erythema was investigated in the UVB and UVA region from 294 nm to 374 nm in skin type II and III individuals. The maximum of the action spectrum in the UVB range was measured at 298.5 nm and an additional maximum was found at 362 nm in the UVA range. The action spectrum is compared with previous spectra from the literature and with the current standard erythema curve of the CIE as well as with other photobiological action spectra. Our results suggest a UVA/UVB boundary at 330 nm.     

Daily Variation of UV‐induced Erythema and the Action of Solar Filters

UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In addition, skin sensitivity shows daily variations, which can interfere in the detection of the efficacy of the filters. Here, we studied the UV‐induced erythema in hairless rats at two times of the day (light and darkness) using a colorimeter method. The effect of an emulsion with solar filters with or without melatonin was also assayed. Results indicate that the value of a* (from CIELAB color space values L* a* b) was the most useful variable to evaluate the erythema. However, at the UV intensity used, erythema was only detected when irradiation was carried out during the activity phase of the animal, enabling the detection of the protective action of the sunscreen at this time. Thus, daily variations in skin sensitivity have been demonstrated and should be taken into account in dermatological research.     

Some new applications of the biamperostat catalytic-kinetic determination of copper, peroxidase, glucose oxidase, thyroxine and 5-chloro-7-iodo-8-hydroxyquinoline.

Biamperometrically observable reactions can be evaluated by the “potentiostat” method with a current-to-voltage transducer. Some further examples of the application of this “biamperostat” are described: the copper(II)-catalyzed autodecomposition of hydrogen peroxide, the horseradish peroxidase-catalyzed oxidation of iodide with hydrogen peroxide, the glucose oxidase-catalyzed oxidation of glucose with molecular oxygen and the iodine (in organic compounds )-catalyzed oxidation of arsenic(III) with cerium(IV). 1,10-Phenanthroline is determined indirectly by its inhibitory action on copper(II).     

Mangan(IV)-Komplexe mit dreizähnigen diaciden Liganden. Kristallstruktur von Acetylacetonato-salicylaldehydbenzoylhydrazonato(2−)-methanol-mangan(III)

Manganese(IV) Complexes with Tridentate Diacidic Ligands. Crystal Structure of Acetyl-acetonato-salicylaldehydebenzoylhydrazonato(2?)-methanol-manganese(III) The manganese(IV) chelates of salicylaldehyde benzoylhydrazone and salicylaldehyde salicylhydrazone were synthesized by ligand exchange reactions using bis(acetylacetonato)manganese(II), tris(acetylacetonato)manganese(III) as well as manganese(III) acetate. The brown complexes show the expected molecular ions in the APCI mass spectra. As an intermediate compound acetyacetonato-salicylaldehydebenzoylhydrazonato(2?)-methanol-manganese(III) was isolated and characterized by X-ray structural analysis. Crystallographic data see “Inhaltsübersicht”.     

Impact of Long‐Wavelength Ultraviolet A1 and Visible Light on Light‐Skinned Individuals

Solar radiation is known to be a major contributor to the development of skin cancer. Most sunscreen formulations, including those with broad spectrum, offer minimal protection in long‐wavelength ultraviolet A1 (UVA1; 370–400 nm) and visible light (VL; 400–700 nm) domain. There is limited information regarding the impact of this broad waveband (VL + UVA1, 370–700 nm) on those with light skin. In this study, ten healthy adult subjects with Fitzpatrick skin phototypes I–III were enrolled. On day 0, subjects' lower back was exposed to a VL + UVA1 dose of 480 J cm^?2. A statistically significant increase in erythema immediately after irradiation compared with subjects' baseline nonirradiated skin was observed. Clinically perceptible erythema with VL + UVA1 is a novel finding since the erythemogenic spectrum of sunlight has primarily been attributed to ultraviolet B and short‐wavelength ultraviolet A (320–340 nm). The results emphasize the need for protection against this part of the solar spectra and warrant further investigation.     

Sun-reactive Skin Type in 4912 French adults participating in the SU.VI.MAX study

Phototype classifications were initially developed in an attempt to predict the skin reactions of patients to phototherapy and are now widely used to advise individuals with regard to sun protection. A transversal study was conducted on the SU.VI.MAX cohort to estimate the frequency of sun-reactive skin features in a large, general adult population-based sample, and to describe the associations between these features. The data were collected 3 years after the beginning of the SU.VI.MAX nutritional intervention study on 4912 volunteers (2868 women aged 35-60 years and 2044 men aged 45-60 years). A multiple correspondence analysis was performed to study the associations between the features. The results showed that these features correspond to a one-dimensional phenomenon, which allowed us to establish a score to summarize skin sensitivity to sun exposure. Furthermore, we found a link between gender and phototype using the Césarini classification (phototype > or = IV: 37% of women, 47% of men). The analysis of the relationship with sun-reactive skin features and the score revealed the same trend. Phenotypic evaluation appears to be a good estimator of skin sensitivity to sun exposure for clinical screening or for use in research, and is easy to collect at a lower cost. Moreover, the sun sensitivity difference between gender should be considered in education about photoprotection.     

Extraction and concentration of palladium(II) from simulated refining process solutions using 1<Emphasis Type="Italic">Н</Emphasis>-1,2,4-triazole derivatives

A procedure was developed for recovery and concentration of residual palladium(II) from a “lean” refining solution by extraction with 1Н-1,2,4-triazole derivatives. Palladium(II) is extracted quantitatively from 1 M hydrochloric acid solutions and under optimum conditions is selectively separated from platinum(IV) and rhodium(III).     

Coagulation and heterocoagulation interactions of components in aqueous dispersed systems microcrystalline cellulose–TiO<Subscript>2</Subscript>, microcrystalline cellulose–TiOSO<Subscript>4</Subscript>, and TiO<Subscript>2</Subscript>–TiOSO<Subscript>4</Subscript>

A procedure was developed for recovery and concentration of residual palladium(II) from a “lean” refining solution by extraction with 1Н-1,2,4-triazole derivatives. Palladium(II) is extracted quantitatively from 1 M hydrochloric acid solutions and under optimum conditions is selectively separated from platinum(IV) and rhodium(III).     

MNDO calculations on borazine derivatives. The substitution of one [HNBH] fragment for one [HCCH] fragment in benzene to form the azaborines and the nature of the cyclotrimer of the 1,2-isomer

The three azaborine isomers with the formula C₄H₆BN, 1,2-, 1,4-, and 1,3-azaborine ( I , II , and III ), have been examined using MNDO (m odified n eglect of d iatomic o verlap) calculations. The most stable azaborine was I (heat of formation -8.147 kcal/mol), followed by II (+11.60 kcal/mol) and III (+16.64 kcal/mol). Qualitatively, although the π- and π*-orbitals calculated for the azaborines exhibited an ordering similar to that in benzene and borazine, the HOMO/LUMO energy differences (9.27, 9.68, and 8.44 eV, respectively) were smaller than was the difference calculated for borazine (12.81 eV), but of the same magnitude as the difference for benzene (9.76 eV). With the exception of borazine, each molecule had a π-orbital for the HOMO and a π*-orbital for the LUMO ; borazine's LUMO was a π*-orbital. The calculated shapes and atomic contributions for the π-and π*-orbitals of the azaborines were best described as “hybrids” of the π- and π*-orbitals of benzene and borazine. As was observed for the π- and π*-orbitals of borazine, the azaborines exhibited increased orbital density at the nitrogen atom in the π-bonding orbitals and at boron in the π-antibonding orbitals, as would be predicted from electronegativity considerations. Although I and II exhibited significant double- and single-bond localization, all of the ring bonds in III were delocalized. The delocalization in III was not uniform but, rather, resembled two inequivalent fused allyl systems. The cyclotrimer ( IV ) of 1,2-azaborine (heat of formation -44.07 kcal/mol), based purely on thermodynamic considerations, was predicted to form spontaneously from three monomer molecules with the concurrent loss of three molecules of dihydrogen. The cyclotrimers that could theoretically be produced from 1,2-azaborine without the loss of dihydrogen ( IVc and IVt ) were each calculated to be less stable (heats of formation +24.45, and +33.29 kcal/mol, respectively) than was the experimentally observed IV . The carbon molecules triphenylene ( TP ) and cis- and trans-4a,4b,8a,8b,12a,12b- hexahydrotriphenylene ( TPc and TPt ) (heats of formation +76.79, +101.6, and +103.1 kcal/mol, respectively) were each calculated to be less stable than were the azaborine cyclotrimer analogs, as was observed in comparisons of benzene with the azaborines and borazine.     

Quantification of UV-induced erythema and pigmentation using computer-assisted digital image evaluation

Photography has been used in human skin research for some time. With the advent of digital photography in recent years, its use has increased. However, the focus has now turned from documentation to actual analysis and quantification of skin color changes. The advantages of digital photography outweigh any shortcomings as long as consistent, standardized procedures are followed and quality control is implemented. We present a simple procedure to standardize images and discuss a computer-assisted digital image evaluation (CADIE) technique to quantify skin color changes following UV exposure. The CADIE approach is illustrated with examples from two different studies on UV responses in human skin. Using the Commission Internationale de l'Eclairage L*a*b* color coordinate system in combination with a personal computer and image-editing software, we analyzed digital images obtained in these two studies. We demonstrate the feasibility of using digital photography for objective evaluation of UV erythema in different racial/ethnic groups and for measuring pigmentation changes caused by repeated exposures over a period of several weeks. Our results indicate how objective assessment using CADIE can be an adjunct to visual and optical observation in clinical and scientific evaluations.     

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, and trimethylstannyl derivatives of 3,3-dimethylcyclopropene VII. 3,3-Dimethyl-1-(trimethylstannyl) cyclopropene

The quantum mechanical force fields (QMFF's) of 3,3-dimethyl-1-(tert-butyl)cyclopropene (I), 3,3-dimethyl-1-(trimethylsilyl)cyclopropene (II), 3,3-dimethyl-1-(trimethylgermyl)cyclopropene (III), and 3,3-dimethyl-1-(trimethylstannyl)cyclopropene (IV) were calculated at the HF/3-21G*//HF/3-21G* level. The set of scale factors for the correction of HF/3-21G*//HF/3-21G* QMFF of II was determined using its well-characterised vibrational spectrum. Transferral of the set of scale factors obtained for II to the QMFF's of I, III and IV and calculation of the fundamental frequencies resulted in good agreement between the calculated and previously assigned experimental frequencies of III. This again demonstrates the feasibility of transferral of a set of scale factors obtained for the correction of the QMFF of a molecule to others containing heteroatoms from the same column of the Mendeleyev Periodic Table. Thus the calculations performed permitted the accurate assignment of the fundamental vibrational frequencies in the experimental IR spectrum of IV. The vibrational frequencies of 3,3-dimethyl-1-(tert-butyl)cyclopropene (I) were also calculated from the HF/6-31G*//HF/6-31G* QMFF, scaled by the set of scale factors used previously for the HF/6-31G*//HF/6-31G* QMFF's of II and III. Regularities in the trends of some vibrational frequencies with increasing atomic number of the heteroatom are observed.