Amount Of Melanin Research Articles

Cytotoxic effect of a 3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazole derivative compound in human melanoma cells

Melanoma represents the most forceful derm cancer with a high rate of mortality. Although chemotherapy has been commonly used in the treatment of melanoma, drug resistance and side effects of conventional chemotheurapeutics negatively affect the continuity and success the treatment. 1,2,4 triazole derivatives are popular compounds of recent years with anti-microbial, anti-inflammatory, analgesic, anti-viral, anti-proliferative and COVID-19 associated anti-fungal activities. However, studies that revealed the effects of 1,2,4 triazole compounds on melanoma cells are limited. The aim of this study was to investigate the effects of a 3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazole derivative (B9) compound on cytotoxicity and cell cycle using MTT and flow cytometry, respectively and the inhibitory effect on tyrosinase in human melanoma (VMM917) cells using colorimetric assay for melanin content. The compound B9 exhibited a selective cytotoxic effect (4.9-fold) on VMM917 cells compared to normal cells. B9 induced cell cycle arrest at the S phase and also decreased the amount of melanin in the cells. The results suggest a novel candidate drug in melanoma therapy. The detailed investigation of the molecular mechanism of this selective cytotoxic effect will provide understanding on the usability of B9 as an alternative chemotherapeutic agent in melanoma.

Ashitaba (Angelica keiskei) leaves extract cream 8% inhibited the increase of melanin amount as effective as hydroquinone cream 4% and inhibited the increase of tyrosinase enzymes not as effective as hydroquinone cream 4% in the ultraviolet B-exposed Guin

Background: Excessive sun exposure results in increased activity of the tyrosinase enzyme and the amount of melanin in the skin which causes hyperpigmentation, a sign of premature aging. The purpose of this study was to prove that Ashitaba (Angelica keiskei) leaves extract cream 8% inhibited the increase of melanin and tyrosinase enzymes as effective as hydroquinone cream 4% in the ultraviolet B-exposed guinea pig (Cavia porcellus) skin.
 Methods: This study used a randomized post-test only control group design. The subjects were 36 male guinea pigs (Cavia porcellus). Subjects were divided into two groups, the hydroquinone cream 4% group and the Ashitaba leaves extract cream 8% group exposed to UVB light. Skin samples were collected 48 hours after the last exposure to measure the tyrosinase enzyme levels using the ELISA method and the amount of melanin was examined by Masson-Fontana staining.
 Results: The mean levels of tyrosinase in the hydroquinone cream 4% group was 19.51 ± 5.16 ng/L and the Ashitaba leaves extract cream 8% group was 23.76 ± 3.09 ng/L (p = 0.005). The mean amount of melanin in the hydroquinone cream 4% group was 2.98 ± 2.27% and the Ashitaba leaves extract cream 8% group was 4.77 ± 3.33% (p = 0.069).
 Conclusion: The administration of Ashitaba (Angelica keiskei) leaves extract cream 8% inhibited the increase of melanin amount as effective as hydroquinone cream 4% and inhibited the increase of tyrosinase enzymes not as effective as hydroquinone cream 4% in the ultraviolet B-exposed guinea pig (Cavia porcellus) skin.

Synthesis and Activity of New Schiff Bases of Furocoumarin

Abstract Furocoumarins, such as 8-MOP, are the most common medications used to relieve the symptoms of vitiligo clinically. Some furocoumarins also showed excellent performance in an anti-bacterial assay. This paper describes the synthesis of a series of novel Schiff bases (6a-6k), and their promotion in melanogenesis and anti-bacterial properties were studied in vitro. The pigment production of B16 cells and bacterial inhibition ring assay were applied for the bioactivity of 6a-6k. According to the results, a stronger promotion on pigment content was observed, when six compounds co-cultured with cells, compared with positive control (8-MOP). Significantly, compound 6k (237%) as the most active was found to increase the amount of melanin more than 1.7 times compared with 8-MOP activation rate (136%). All the compounds could moderately retard C. albicans growth. Interestingly, aldehyde 5, which possessed a broader antibacterial spectrum, showed the highest inhibition against C. albicans as well and much better than the positive control (Amphotericin B). Studies of 6k in animal models of vitiligo and related molecular mechanism are presently under way, with the aim of discovering an anti-vitiligo leading compound.

Adaptation and co-adaptation of skin pigmentation and vitamin D genes in native Americans.

We carried out an exhaustive review regarding human skin color variation and how much it may be related to vitamin D metabolism and other photosensitive molecules. We discuss evolutionary contexts that modulate this variability and hypotheses postulated to explain them; for example, a small amount of melanin in the skin facilitates vitamin D production, making it advantageous to have fair skin in an environment with little radiation incidence. In contrast, more melanin protects folate from degradation in an environment with a high incidence of radiation. Some Native American populations have a skin color at odds with what would be expected for the amount of radiation in the environment in which they live, a finding challenging the so-called "vitamin D-folate hypothesis." Since food is also a source of vitamin D, dietary habits should also be considered. Here we argue that a gene network approach provides tools to explain this phenomenon since it indicates potential alleles co-evolving in a compensatory way. We identified alleles of the vitamin D metabolism and pigmentation pathways segregated together, but in different proportions, in agriculturalists and hunter-gatherers. Finally, we highlight how an evolutionary approach can be useful to understand current topics of medical interest.

Periodic albinism of a widely used albino mutant of Xenopus laevis caused by deletion of two exons in the Hermansky-Pudlak syndrome type 4 gene.

The periodic albino mutant of Xenopus laevis is a recessive mutant, in which reduced amounts of melanin appear in the retinal pigment epithelium (RPE) and in melanophores at the late embryonic stage, after which both RPE and melanophores gradually depigment. Three types of pigment cells (melanophores, iridophores and xanthophores) have been reported to be affected in this albino. However, the causative gene of the periodic albinism remains unknown. Hermansky–Pudlak syndrome (HPS) is an autosomal recessive disorder that affects humans and mice, which is caused by defective biogenesis of lysosome‐related organelles (LROs). Two subgenomes (L and S) are present in the allotetraploid frog X. laevis. Comparison of genes between the chromosomes 1L and 1S revealed that the HPS type 4 (hps4) gene was present only in chromosome 1L. In the albino mutant, a 1.9 kb genomic deletion in the hps4.L gene including exons 7 and 8 caused a premature stop codon to create a truncated Hps4 protein. Injection of wild‐type hps4.L mRNA into mutant embryos rescued the albino phenotype. These findings indicate that hps4 is a causative gene for the periodic albinism in X. laevis. The phenotype of this mutant should be reassessed from the perspective of LRO biogenesis.

MicroRNA-340 is involved in ultraviolet B-induced pigmentation by regulating the MITF/TYRP1 axis.

ObjectiveThere is growing evidence that ultraviolet B (UVB) irradiation can change the expression profile of microRNAs (miRNAs) in immortalized human epidermal melanocytes (Pig-1). We aimed to investigate the effect of miR-340 on regulating UVB-induced pigmentation.MethodsReal-time quantitative PCR (qRT-PCR) was used to evaluate the expression of miR-340 in Pig-1 cells. Immunoblotting analysis, qRT-PCR, and luciferase reporter assays were used to detect the potential target of miR-340. The sodium hydroxide dissolution assay was used to assess the effect of miR-340 on changes in melanin content.ResultsExpression of miR-340 was reduced in human Pig-1 cells after UVB irradiation. We found a negative correlation between miR-340 and melanocyte inducing transcription factor (MITF) in Pig-1 cells after UVB irradiation. Knockdown and overexpression of MITF in Pig-1 cells down- and upregulated melanogenesis, respectively. Overexpression of miR-340 inhibited MITF expression, reduced the amount of melanin, and suppressed expression of multiple key molecules involved in the pigment synthesis pathway, whereas knockdown of miR-340 showed the opposite results.ConclusionsOur results showed that miR-340 inhibited melanogenesis by regulating the downstream molecules of MITF and its signaling pathways, suggested that miRNA-340 may be a new target for the clinical treatment of UVB-induced pigmentation.

Role refinement of melanin synthesis genes by gene knockout reveals their functional diversity in Pyricularia oryzae strains

Pyricularia oryzae is a plant pathogenic fungus that severely affects rice production. Past studies, primarily using mutants generated by spontaneous mutations or artificial physical and chemical mutagenesis, have determined that melanin is required for appressorium turgor, penetration, and virulence of P. oryzae. However, these roles need to be verified by gene knockout and/or overexpression in different strains considering the potential differences in the level of virulence. Here, we confirmed the indispensable roles of melanin in the development and virulence of P. oryzae by knocking out and over-expressing three melanin synthesis genes (ALB1, RSY1, and BUF1) in two wild-type strains (Guy11 and 70-15). Deletion of ALB1, RSY1, or BUF1 led to loss of melanin and virulence in both strains. ALB1, RSY1 and BUF1 in Guy11, and BUF1 in 70-15 were required for conidiation, respectively. ALB1, RSY1, and BUF1 were required for conidial resistance to environmental stresses (UV exposure, oxidization, and freezing damage) in both strains. Guy11 cells had greater amounts of melanin and more transcripts of melanin synthesis genes than 70-15 cells. Paired culture experiments between the deletion or over-expression mutants of melanin synthesis genes suggested that the reaction catalyzed by Buf1, but not Alb1 and Rsy1, was likely a rate-limiting step in melanin biosynthesis in 70-15. These results expand our understanding on melanin and its synthesis genes in P. oryzae as well as its responses to biotic and abiotic environments.

The Effect of Black Cumin Extract Cream (Nigella Sativa) On Melanin Pigment Level In Rats (Rattus Norvegicus) Exposed With Ultraviolet-B rays

Exposure to ultraviolet (UV) radiation from the sun may cause photo aging which is characterized by uneven pigmentation and brown spots. Melanin acts to protect the skin against DNA damage due to UV radiation. Sunscreen is a cosmetic preparation that can reflect sunlight, especially in areas with UV wave emulsions. This study aims to determine the effect of black cumin extract cream on the amount of melanin pigment in rat skin exposed to ultraviolet-B rays. An experimental post-test only control group study was conducted from October 2019 - February 2020. A total of 30 rats were divided into 6 groups, namely the KN group (without treatment), P1 (basic cream), P2 (black cumin extract cream 0.25% ), P3 (0.5% cream), P4 (0.75% cream) and KP (Parasol sunscreen cream). Rats in group P4 showed significantly lower amounts of melanin (41.5 ± 10.4) than other groups (KN 41.5, P1 86.0, P2 84.7 and P3 78.7; p <0.05). However, the least amount of melanin pigment was found in the KP group (10.0 ± 1.82). It can be concluded that the topical black cumin extract cream can topically reduce the amount of melanin pigment.

Idiosyncratic liver pigment alterations of five frog species in response to contrasting land use patterns in the Brazilian Cerrado.

BackgroundChanges in land use trigger environmental changes that can lead to decreased biodiversity and species loss. The liver is an essential detoxification organ that reflects systemic physiological responses to environmental changes. Here, we tested whether contrasting land use patterns influence the amount of substances from the hepatic cellular catabolism and melanomacrophages (MMs) of five anuran species in the Brazilian Cerrado.MethodsWe collected the same five species of pond-dwelling frogs in one protected area and in an area with intense agricultural activity. We used routine histological and histochemical techniques to quantify the area occupied by lipofuscin, melanin, and hemosiderin in the liver of two frogs Leptodactylus fuscus, Physalaemus cuvieri, and three tree-frogs Dendropsophus minutus, Scinax fuscomarginatus, and Boana albopunctata. We classified land use types in a buffer around each pond based on satellite images. We then used a double-constrained Correspondence Analysis, a recently developed ecological method to relate functional traits to environmental variables, to test the effect of each land use type on the area of each liver pigment.ResultsThere was an increase in the amount of melanin in environments with high proportion of agriculture, as well as variation in the amount of lipofuscin and hemosiderin. Liver pigments of P. cuvieri and B. albopunctata varied more strongly in response to land use types, suggesting they could be good indicator species. Therefore, the area of MMs in the liver and the metabolic products in their cytoplasm can be used as biomarkers of environmental changes in regions with intense agricultural activities. Our results add a new perspective to the influence of land use patterns on environmental health by highlighting the effect of environmental changes on internal morphological aspects of animals.

Lactobacillus helveticus-Fermented Milk Whey Suppresses Melanin Production by Inhibiting Tyrosinase through Decreasing MITF Expression.

Whey obtained from milk fermented by the Lactobacillus helveticus CM4 strain (LHMW) has been shown to improve skin barrier function and increase skin-moisturizing factors. In this study, we investigated the effects of LHMW on melanin production to explore the additional impacts of LHMW on the skin. We treated mouse B16 melanoma cells with α-melanocyte-stimulating hormone (α-MSH) alone or simultaneously with LHMW and measured the amount of melanin. The amount of melanin in B16 cells treated with α-MSH significantly increased by 2-fold compared with that in control cells, and tyrosinase activity was also elevated. Moreover, treatment with LHMW significantly suppressed the increase in melanin content and elevation of tyrosinase activity due to α-MSH. LHMW also suppressed the α-MSH-induced increased expression of tyrosinase, tyrosinase-related protein 1 (TRP1), and dopachrome tautomerase (DCT) at the protein and mRNA levels. Furthermore, the mRNA and protein microphthalmia-associated transcription factor (MITF) expression levels were significantly increased with treatment with α-MSH alone, which were also suppressed by LHMW addition. LHMW suppression of melanin production is suggested to involve inhibition of the expression of the tyrosinase gene family by lowering the MITF expression level. LHMW may have promise as a material for cosmetics with expected clinical application in humans.

The Difference between the Effect of Green Tea Cream and Tocopherol on Decreasing Level of Tyrosinase Enzyme and Amount of Melanin in Rattus norvegicus Exposed to UVB Rays

Introduction: Green tea and tocopherol are potent antioxidants used to treat melasma. However, whether green tea or tocopherol is superior remains unclear. Objective: To compare the effectiveness between green tea and tocopherol in decreasing the amount of melanin and tyrosinase level in wistar rats exposed to UVB rays.Methods: The experimental study took 30 male Wistar rats randomly and divided them into 3 groups. The control group (C-G) was given basic topical cream, GT-G was given green tea topical cream and TC-G was given tocopherol topical cream. All rats were exposed to UVB every Monday, Wednesday and Friday for 4 weeks, whereas topical creams were smeared every day. Topical creams smearing on the same day with UVB exposure was performed 20 minutes before exposure and 4 hours after UVB exposure. The doses of UVB were 50 mJ/cm2 in first week, 70mJ/cm2 in the second week and 80mJ/cm2 in the third and fourth weeks. The amount of melanin was measured using pixel method and the tyrosinase level was measured using ELISA.Results: Anova analysis indicates that the amount of melanin and tyrosinase level are significantly different between groups, p<0.05. Post Hoc LSD analysis indicates that the amount of melanin in GT-G and TC-G are significantly lower than that of C-G, p<0.05. The amount of melanin in GT-G is lower than that of TC-G, p<0.05. The tyrosinase level in GT-G is significantly lower than that of C-G and TC-G, p<0.05. Meanwhile, the tyrosinase level in TC-G is lower than that of C-G but insignificantly, p>0.05.� Conclusion: Green tea topical treatment is significantly capable of decreasing the amount of melanin and tyrosinase level better than tocopherol.

Effect of Vitiligo on Auditory Functions: Is There Any Association?

Introduction Vitiligo is an acquired pigmentary disorder of unknown etiology, clinically characterized by whitish macules caused by selective loss of melanocytes. There are many melanocytes in the human cochlea. Recent studies have suggested a direct relation between cochlear dysfunction and decreased amounts of melanin. Objective To determine the effect of vitiligo on auditory function. Methods The present prospective, case control study was performed over a period of 1 year in patients between 15 and 40 years old with nonsegmental disease and the same number of controls. Pure tone audiometry (PTA) and Otoacoustic emission (OAE) were performed to analyze the correlation between vitiligo and auditory function. Results The mean pure tone audiometric threshold in the right ear at 0.5, 8 kHz, and in the left ear at the frequency of 8 kHz in the case group were significantly higher as compared with controls. The average band reproducibility (%) in the right and left ear of controls was significantly higher at the frequency of 4 kHz as compared with cases. It has been observed that signal to noise ratio was statistically higher at the frequency of 5kHz in the right ear and at 2, 3, and 5kHz in the left ear in controls as compared with cases. On the basis of disease type and duration of disease; mean pure tone audiometric threshold, average band reproducibility and signal to noise ratio, no significant effect was observed in the present study. Conclusion Vitiligo has an effect on cochlear function irrespective of the duration or distribution of the disease.

Photoprotection and Skin Pigmentation: Melanin-Related Molecules and Some Other New Agents Obtained from Natural Sources.

Direct sun exposure is one of the most aggressive factors for human skin. Sun radiation contains a range of the electromagnetic spectrum including UV light. In addition to the stratospheric ozone layer filtering the most harmful UVC, human skin contains a photoprotective pigment called melanin to protect from UVB, UVA, and blue visible light. This pigment is a redox UV-absorbing agent and functions as a shield to prevent direct UV action on the DNA of epidermal cells. In addition, melanin indirectly scavenges reactive oxygenated species (ROS) formed during the UV-inducing oxidative stress on the skin. The amounts of melanin in the skin depend on the phototype. In most phenotypes, endogenous melanin is not enough for full protection, especially in the summertime. Thus, photoprotective molecules should be added to commercial sunscreens. These molecules should show UV-absorbing capacity to complement the intrinsic photoprotection of the cutaneous natural pigment. This review deals with (a) the use of exogenous melanin or melanin-related compounds to mimic endogenous melanin and (b) the use of a number of natural compounds from plants and marine organisms that can act as UV filters and ROS scavengers. These agents have antioxidant properties, but this feature usually is associated to skin-lightening action. In contrast, good photoprotectors would be able to enhance natural cutaneous pigmentation. This review examines flavonoids, one of the main groups of these agents, as well as new promising compounds with other chemical structures recently obtained from marine organisms.

Near-infrared transillumination imaging combined with aperture photometry for the quantification of melanin in the iris pigment epithelium.

Near-infrared transillumination is used in the diagnosis and the management of different eye diseases. In particular, it enables the visualization of melanin in the pigment epithelium of the iris. This technique is valuable in such conditions as pigment dispersion syndrome and Adie's tonic pupil. Thus, objective quantification of the amount of melanin shedded from the iris pigment epithelium may help in the management of these conditions. By combining aperture photometry with near-infrared iris transillumination this can be achieved. A total of 4 patients (7 eyes) were examined. Three patients were diagnosed with pigment dispersion syndrome in both eyes. One patient had Adie's tonic pupil in one eye. Near-infrared iris transillumination was performed by using a prototype apparatus. Aperture photometry measurements were carried out through specially developed software. The signal-to-noise ratio of the prototype apparatus was 52 dB (399:1). Each pixel within the near-infrared transillumination image corresponded with an area size of the iris of 85 μm x 83 μm. Measurements were taken from several points of the iris in all patients. The average aperture photometry value of transillumination defects was 1321.53 (ADU) ± 501.08 SD, while the average aperture photometry value of the papillary ruff was 90.83 (ADU) ± 53.4. On average transillumination defects transmit 14.55 times more near-infrared light than the papillary ruff. A prototype apparatus for the capture of near-infrared iris transillumination images and custom software enabling aperture photometry measurements of the obtained images has been developed for the purpose of this study. This study demonstrates a potential application of this technique in the diagnosis and management of patients with such conditions as pigment dispersion syndrome and Adie's tonic pupil.

Bogong Moths Are Well Camouflaged by Effectively Decolourized Wing Scales

Moth wings are densely covered by wing scales that are assumed to specifically function to camouflage nocturnally active species during day time. Generally, moth wing scales are built according to the basic lepidopteran Bauplan, where the upper lamina consists of an array of parallel ridges and the lower lamina is a thin plane. The lower lamina hence acts as a thin film reflector having distinct reflectance spectra that can make the owner colorful and thus conspicuous for predators. Most moth species therefore load the scales’ upper lamina with variable amounts of melanin so that dull, brownish color patterns result. We investigated whether scale pigmentation in this manner indeed provides moths with camouflage by comparing the reflectance spectra of the wings and scales of the Australian Bogong moth (Agrotis infusa) with those of objects in their natural environment. The similarity of the spectra underscores the effective camouflaging strategies of this moth species.

A split-face comparative study to evaluate the efficacy of 50% pyruvic acid against a mixture of glycolic and salicylic acids in the treatment of acne vulgaris.

One of the ways to treat acne is by using chemical peels. Salicylic, glycolic and pyruvic acids due to their keratolytic and antibacterial properties are often recommended for acne patients. The aim of the study was to compare the effect of a preparation containing glycolic and salicylic acids with pyruvic acid. 14 women diagnosed with acne took part in the study. The facial treatment area was divided into two parts: right (a preparation containing 50% pyruvic acid) and left side ( a preparation containing glycolic and salicylic acids). A series of four treatments was performed at 2-week intervals. Skin parameters, namely hydration, sebum secretion and skin colour were measured. As a result of using 50% pyruvic acid, the hydration of the right side of the face increased statistically and there was a decrease in the amount of melanin in the epidermis. On the left side of the face, there was an increase in skin hydration after using a mixture of glycolic and salicylic acids. The increase in skin hydration on the left side of the chin and nose was not statistically significant. The use of the mixture of glycolic and salicylic acids affected the skin colour on the left side of the face, on the forehead, cheek and nose. Chemical peels affect a wide range of pathological factors of acne. A mixture of acids yields fewer side effects than a single acid used in high concentration, but the therapeutic effects are comparable.

Cellular Lysosomes' Activity for Melanin Reduction on Artificial Skin Tissue.

All eukaryotes have lysosomes which contain hydrolytic enzymes such as protease to degrade waste materials and cellular fragments. As a cellular organelle, lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself. Conversely, melanin has photochemical functions to protect tissue from the harmful effects of ultraviolet rays. However, too much of melanin leads to problems such as hyperpigmentation, requiring materials to maintain and control the amount of melanin. In this study, we found evidence of correlation between lysosome and melanin in a new eco-friendly material, MelanoDerm, a reconstituted 3D human skin model containing normal melanocytes and keratinocytes. Melanin content assay and cell viability were measured, using 2% kojic acid as positive control, while MelanoDerm was exposed to various concentrations of lysosome. Our results indicate that lysosome may be a useful cosmetic agent for the treatment of hyperpigmentation.

A study of dermoscopy for pigmentary lesions among children with pigmentary disorders

Disorders of melanin pigmentation can be divided on morphological grounds into two types- hypomelanosis and hypermelanosis. Hypomelanosis is characterized by a lack of melanin pigment in the skin, which therefore appears white or lighter than the normal colour. In hypermelanosis, there is an increased amount of melanin in the skin. When this excess is confined to the epidermis, the skin appears browner than normal, and when present in the dermis, a slate-grey or blue appearance is produced. Hypermelanosis and hypomelanosis can be generalized and diffuse, or may be localized and circumscribed. Amelanosis is the term applied when there is a total lack of melanin in the skin. A detailed clinical history was elicited with regard to patients’ age, gender, address, age of onset of disorder, type (hypo-/hyper pigmented), site and size of pigmented lesions, familial involvement, associated skin and systemic conditions and the details were recorded on a proforma. A dermoscope is a non-invasive, diagnostic tool which visualizes subtle clinical patterns of skin lesions and subsurface skin structures not normally visible to the unaided eye. Basically, a dermoscope is functionally similar to a magnifying lens but with the added features of an inbuilt illuminating system with the ability to assess structures as deep as in the reticular dermis, and the ability to record images.

Dermoscopic approach to inflammatory lesions in skin of color

Introduction: Dermoscopy is an in vivo and non-invasive tool that assists as an adjunctive method in the diagnosis of many dermatoses. Dermoscopic studies and research in the field of inflammatory and infective lesions are limited to case series or case reports without definitive criteria. Authors have attempted to describe a very basic approach to dermoscopic diagnosis of inflammatory conditions like psoriasis, eczema, lichen planus, pityriasis rosea, prurigo nodularis, and discoid lupus erythematosus. Aim: To propose basic dermoscopic guidelines in terms of approach to an inflammatory lesion.Summary: Dermoscopy of inflammatory conditions is referred to as 'inflammoscopy'. Basic approach in inflammoscopy is based on 5 dermoscopic parameters which include; i) background colour, ii) vessels, iii) scales, iv) follicular findings and v) specific clues. Dermoscopy helps in the differentiation of many inflammatory lesions by demonstrating characteristic patterns thus aiding in its diagnosis. Uniform and regular dotted vessels are seen in psoriasis. Wickham striae, adherent fabric fibre sign, yellow clod sign and white rosettes are respectively a special clue for the diagnosis of lichen planus, prurigo nodularis, eczema and early DLE lesion. Collarette scales over brownish yellow background are seen in P. rosea. Dermatologist dealing with skin lesions in patients with skin types IV, V, and VI should be aware that there are slight variations in the dermoscopic pattern owing to amount of melanin.

Impact of ultraviolet radiation on dermal and epidermal DNA damage in a human pigmented bilayered skin substitute.

Our laboratory has developed a scaffold-free cell-based method of tissue engineering to produce bilayered tissue-engineered skin substitutes (TESs) from epidermal and dermal cells. However, TES pigmentation is absent or heterogeneous after grafting, due to a suboptimal number of melanocytes in culture. Our objectives were to produce TESs with a sufficient quantity of melanocytes from different pigmentation phototypes (light and dark) to achieve a homogeneous color and to evaluate whether the resulting pigmentation was photoprotective against ultraviolet radiation (UVR)-induced DNA damage in the dermis and the epidermis. TESs were cultured using different concentrations of melanocytes (100, 200, and 1,500 melanocytes/mm2 ), and pigmentation was evaluated in vitro and after grafting onto an athymic mouse excisional model. Dermal and epidermal DNA damage was next studied, exposing pigmented TESs to 13 and 32.5 J/cm2 UVR in vitro. We observed that melanocyte cell density increased with culture time until reaching a plateau corresponding to the cell distribution of native skin. Pigmentation of melanocyte-containing TESs was similar to donor skin, with visible melanin transfer from melanocytes to keratinocytes. The amount of melanin in TESs was inversely correlated to the UVR-induced formation of cyclobutane pyrimidine dimer in dermal fibroblasts and keratinocytes. Our results indicate that the pigmentation conferred by the addition of melanocytes in TESs protects against UVR-induced DNA damage. Therefore, autologous pigmented TESs could ensure photoprotection after grafting.