Distribution Of Melanin Pigment Research Articles

Post-Inflammatory Hyperpigmentation in Dark Skin: Molecular Mechanism and Skincare Implications.

Human skin is characterized by significant diversity in color and tone, which are determined by the quantity and distribution of melanin pigment in the epidermis. Melanin absorbs and reflects ultraviolet radiation (UVR), preventing the damage to genomic DNA in the epidermis and degradation of collagen in the dermis; therefore, darker skin types are thought to be well protected from the photodamage because of the high melanin content. However, increased content of melanin in combination with the extrinsic stress factors causing inflammation such as excess UVR, allergic reactions, or injury can also frequently lead to cosmetic problems resulting in discoloration and scarring. This review summarizes current knowledge on histopathology and likely molecular signatures of one of the most common problems, post-inflammatory hyperpigmentation (PIH). The mechanisms proposed so far are subsequently discussed in the context of other factors characterizing darker skin types. This includes the common cellular features, organization of upper skin layers, and major biomarkers, with particular emphasis on increased propensities to systemic and localized inflammation. Enhanced or prolonged inflammatory responses can not only affect the process of melanogenesis but also have been implicated in injury-related skin pathologies and aging. Finally, we summarize the major cosmetic treatments for PIH and their known anti-inflammatory targets, which can be beneficial for darker skin tones and combined with broad-spectrum filters against UVR.

PENGUJIAN AKTIVITAS EKSTRAK ETANOL KULIT BUAH KECOMBRANG (Etlingera elatior (Jack) R.M.Sm) SEBAGAI INHIBITOR TIROSINASE

Healthy skin should have a flat surface, the texture is soft, elastic, and have the same skin color. Skin color is determined by the size, number and distribution of melanin pigment. Pigment brownish pigment melanin is to protect the skin from UV light scattering. An enzyme that plays a role in this browning reaction is tyrosinase. Browning reaction tyrosinase inhibitor can be inhibited by an enzymatic by an enzymatic reaction in the form of ions or molecules called tyrosinase. Inhibition of tyrosinase is one way to prevent skin hyperpigmentation. Tyrosinase enzyme catalyzes two main reactions in the biosynthesis of melanin, the hydroxylation of L-tyrosin into L-dopa and the oxidation of L-dopa becomes dopakuinon. Polyphenol compounds (Flavonoids) the group is basically have the effect cant inhibit melanogenesis as a tyrosinase inhibitor. Kecombrang a wild plant that has many benefits one of them as a source of natural antioxidants. Based on this research is conducted on the fruit skin kecombrang to see the activity of the enzyme tyrosinase barriers and whether rind kecombrang can inhibit tyrosinase enzyme and with the aim to utilize natural materials and waste that can inhibit the enzyme tyrosinase and can be used as a skin whitheter. Research iniated by the extraction of fruit skins kecombrang using etanol. Flavonid content test on the sample using Mg powder and HCl p, the results show a color change from dark brown to yellow. So positive it contains flavonoids. Measurements were contucted on a maximum wavelength of 478,003 nm, using the substrate L-tyrosine and the enzyme tyrosinase. Using comparators hidroquinon. Of the results of this study concluded that kecombrang fruit peel ectract at a concentration of 2 mg/mL could inhibit amounted to 55,92% and a concentration of 2,5 mg/mL could inhibit amounted to 56,58%.

Emerging role of dermal compartment in skin pigmentation: comprehensive review.

The variations in human skin colour mainly occur due to differences in the distribution of melanin pigment throughout the body, synthesized by epidermal melanocytes which are further taken up by keratinocytes present in epidermis. Recently, it has been discovered that besides these cells, dermis derived fibroblast factors also play a prominent role in regulating skin pigmentation. There exists a signal crosstalk between epidermal melanocytes, keratinocytes and dermal fibroblasts and any impairment in these signalling pathways may give rise to pigmentary disorders. Vitiligo is a hypopigmentary disorder and alteration in the expression level of several fibroblast-specific factors has been reported in the lesional skin of vitiligo patients. In such patients, there is decrease in the expression levels of factors such as basic fibroblast growth factor, stem cell factor (SCF) and keratinocyte growth factor (KGF) along with a steep increase in the expression levels of Dickkopf 1. Patients affected with hyperpigmentary disorder like melasma exhibit a marked increase in SCF and KGF expression levels leading to increase in melanin production and those affected with solar lentigo experience upregulation in the expression levels of SCF, KGF and HGF (hepatocyte growth factor). Hence, we conclude that new therapeutic strategies can be adopted to cure these pigmentary disorders by targeting factors involved in crosstalk signalling between epidermal melanocytes, keratinocytes and dermal fibroblasts.

A Description of Chirolophis japonicus and Ch. saitone (Stichaeidae) Pelagic Larvae from Peter the Great Bay, Sea of Japan

The larval development of Chirolophis japonicus and Ch. saitone from the yolk-sac stage to the settlement on the bottom is described from waters of Peter the Great Bay, Sea of Japan. The pattern of distribution of melanin pigmentation over the body of larvae in these Chirolophis species is formalized for the first time. It consists of six rows, the aggregation on the top of head, and several single melanophores. Despite the similarity between the species, each of them has its specific features that are manifested mainly as a different number of axial skeleton elements (total number of vertebrae and number of rays in the dorsal and anal fins). A conclusion is made that a reliable diagnostic character to identify larvae of Ch. japonicus and Ch. saitone within the period of their development from hatching to settlement can be the number of melanophores at the base of the anal fin rays.

Distribution of Melanin Pigmentation in 33 Organs of Thai Black-Bone Chickens (Gallus gallus domesticus).

Simple SummaryConsumers are selectively attracted to the black-bone chicken breed for the characteristic darkness that is observed in many of its organs. However, the degree of darkness in all organs of the black-bone chicken is still relatively unknown. The question of whether hyperpigmentation is present in every organ or just in some organs is an important one. Additionally, the question of whether a similar hyperpigmentation pattern exists in all animals is also of significant interest. Presently, no reports have yet attempted to explain the distribution and location of the melanin pigment that is present in Thai Royal black-bone chickens. The results of this study will help to provide valuable background knowledge with regard to the anatomy of the black-bone chickens. We found that gender does not have an effect on the hyperpigmentation of each organ in black-bone chickens. Organs and/or tissue samples taken from some of the chickens, such as the heart, kidney, and abdominal fat, did not reveal any degree of hyperpigmentation while the liver of all chickens did not display any degree of hyperpigmentation. Finally, most organs did reveal some degree of melanin pigmentation in all layers. This was true with the exception of certain layers of the collected tissue samples, such as in the tissue samples of the epithelium and the tunica mucosa in some organs, that did not display any degree of pigmentation.The black-bone chicken (Gallus gallus domesticus) is a breed of chicken that is commonly found in Thailand. This breed is known for having a number of black colored organs. Consumers have been notably attracted to the black-bone chicken breed for the characteristic darkness that is observed in many of its organs. However, the degree of darkness in all organs of the black-bone chicken is still in question. Importantly, there have not yet been any published reports on the distribution of melanin pigment in the organs of the black-bone chicken. This research study aims to examine the distribution of the melanin pigment in 33 organs of the Thai black-bone chicken. Ten black-bone chickens (five male, five female) were included in this study. Thirty-two organs including the brain, spinal cord, sciatic nerve, larynx, trachea, syrinx, lungs, heart, pericardium, aorta, brachial vein, kidney, cloaca, oviduct, testis, gastrocnemius muscle, femur, tongue, esophagus, crop, proventriculus, gizzard, duodenum, jejunum, ileum, cecum, pancreas, liver, gall bladder, omentum, abdominal fat, spleen, and skin were examined in this study. Histological sections taken from tissue samples of each of these organs were studied. The findings revealed that the presence of the melanin pigment was not significantly different (p > 0.005) between male and female specimens. Notably, the liver was the only organ in which the melanin pigment had not accumulated. Consequently, there was not a uniform pattern of melanin pigment accumulation throughout the organs of the chickens. The melanin pigment was present in all of the tissue layers of most organs, while the melanin pigment was found in only specific layers of some of the organs. In conclusion, the distribution of melanin pigmentation in the organs of each of the animals in this study was found to be different. However, in some tissue samples, such as those obtained from the liver, no accumulation of the melanin pigment was observed.

Assessment of Parameters Influencing Physiologic Gingival Pigmentation Using a Novel Classification System

Background: Depigmentation has become an important treatment modality among the general population due to the growing esthetic concern about the pigmentation. Previous studies have not considered parameters such as anatomical distribution of gingiva, intensity of pigmentation, and skin color in their classification systems. The purpose of this study was to assess physiologic gingival pigmentation in individuals based on certain gingival parameters and their correlation with skin color for better treatment strategies using a new classification system. Methods: The study was carried out in Ragas Dental College using a cross-sectional design. A total of 112 female dental students were examined for skin color and gingival parameters. The facial gingiva of upper anterior teeth was assessed for gingival phenotype, intensity and distribution of pigmentation. Descriptive statistics were used to describe the data and the associations between variables were done using chi-square test (P < 0.05). Results: It was found that skin color has a significant association with the intensity of pigmentation (P = 0.0001). In both dark and fair skinned individuals, Class II pigmentation (47%, 23.2%) with thick phenotype (62.5%, 35%) was most prevalent. Dark-skinned individuals were also found to have a generalized distribution of melanin pigmentation (19%) with high intensity of pigmentation (28.5%) predominantly. Fair-skinned individuals had a patchy distribution of melanin pigmentation with low intensity of pigmentation (37%). Conclusions: The association of skin color with various parameters affecting gingival pigmentation can help in determining the depigmentation treatment strategies.

Evaluation of gingival melanin pigmentation in pediatric population- An observational study.

Aim:The aim of this study is to evaluate the gingival melanin pigmentation in the Indian pediatric population. The aim of this study is to find any association between age and melanin distribution, age and intensity of melanin distribution, sex and melanin distribution, sex and intensity of melanin distribution, skin tone and melanin distribution, skin tone and intensity of melanin distribution and finally the association between melanin distribution and intensity.Background:Pigmentation on the interdental papilla, attached and marginal gingiva is commonly found in various races across the world. There is lack of literature for documentation of the same in the pediatric population.Materials and Methods:Intensity of melanin pigmentation was observed by the gingival melanin pigmentation index (class 1- class 6) as given by Ponnaiyan et al. This cross-sectional, observational study was conducted in the Institution. 100 children were selected from the age group of 1-12 years of age. The association between the various parameters were verified using Chi square test.Results:With the findings of the present study, it can be concluded that the distribution of melanin pigmentation is not affected by age, sex and skin color. The intensity of melanin pigmentation is not affected by age and sex. The skin colour can be used as a predictor to know the intensity of melanin pigmentation in both anteriors and posteriors.

Histologic Distinction Between Subungual Lentigo and Melanoma

The distinction between a benign subungual pigmented macule (lentigo) and an early lesion of melanoma in situ can be difficult. To identify histologic parameters of potential diagnostic value, we retrospectively reviewed biopsies and excisions of 35 pigmented nail lesions. We studied 20 melanomas (10 invasive and 10 noninvasive) and 15 benign subungual melanotic lentigines. Ten specimens of normal nail apparatus obtained for reasons other than melanonychia were also examined as controls. The parameters, which were analyzed, included the density of melanocytes, the presence of multinucleated cells, pagetoid spread, cytologic atypia, inflammation, and the distribution of melanin pigment. The density of melanocytes was measured as the number of cells per 1 mm stretch of subungual dermo-epithelial junction [=melanocyte count (MC)]. The MC for invasive melanomas was as follows: mean=102, median=92.5, and range 52 to 212. For noninvasive (only in situ) melanoma, the mean MC was 58.9, median 51, and range 39 to 136. For benign subungual melanotic macules, the mean MC was 15.3, median 14, and range 5 to 31. In normal controls, the mean MC was 7.7, median 7.5, and range 4 to 9. Qualitative features associated with in situ melanoma and useful for its distinction from benign subungual melanotic macules included the presence of confluent stretches of solitary units of melanocytes, multinucleated melanocytes, lichenoid inflammatory reaction, and florid pagetoid spread of melanocytes.

A New Approach in the Determination of Eumelanin in Human Hair Using near Infrared Spectroscopy

Page 10 NIR news Vol. 16 No. 6 (2005) The aetiology of skin cancers is a complex interaction between genetic characteristics (phenotypically expressed by skin complexion) and exposure to sun. These two factors, complexion and exposure to sun, modulate the risk of different tumours in a different way. In detail, for melanoma, risk is associated with fair complexion (light blonde or red hair, high number of naevi and freckles, tendency to sunburn) and with intense and intermittent exposures like those experienced during holidays. Risk profiles are defined by semi-quantitative empiric parameters (scale of hair, eye and skin colour, acute reactivity scale, such as MED, Minimal Erithemal Dose) for the tendency to sunburn. Knowledge of the biochemistry of skin pigments, the melanins, has made it possible to identify a biological marker. Melanins are biopolymers present in the hair and epidermis. There are two distinct types of melanin pigments: the eumelanins, efficient in photo-protection and responsible for black and brown colour and the pheomelanins, bad at photo-protection and responsible for yellow and reddish colour. Most Caucasian populations have intermediate skin and hair colour and present these two kind of pigment in different ratios. This study about the distribution of melanin pigment in the population in general and in groups of subjects with different cutaneous tumours is an original work, starting from results obtained in the biochemical field. The turning point from empirical characterisation to biochemical characterisation of phenotypes by the quantitative determination of melanins in human hair can lead to the selection of groups with an elevated risk of cutaneous tumours. In these groups of people it will be possible to carry out more thorough diagnostic tests (dermatological inspection of skin). A multicentric case-control study was carried out in different European countries. Three groups of about 300 cases were recruited for each cutaneous cancer (cutaneous melanoma, squamous cell carcinoma and basal cell carcinoma) and 300 controls. For each group of people, in addition to data concerning phenotype and sun exposure Eumelanin in Human Hair

4,4&amp;prime;-Dihydroxybiphenyl as a New Potent Tyrosinase Inhibitor

The color of mammalian skin is determined by many factors, for which visible ones are the degree and distribution of melanin pigmentation. Because tyrosinase, (polyphenol oxidase) is the key enzyme for melanin biosynthesis, the use of various tyrosinase inhibitors is a common practice for whitening purpose in cosmetics. In the present study, the inhibition of tyrosinase by 4,4'-dihydroxybiphenyl (44'-BP) was investigated. In addition to tyrosinase inhibiting activity, melanin biosynthesis was assessed in B16F10 melanoma cells (B16 cells). The results showed that 44'-BP exhibits a strong anti-tyrosinase activity with IC50=1.91 microM. The kinetic analysis of tyrosinase inhibition revealed that 44'-BP acts a competitive inhibitor (Ki=4.0 x 10(-4) M at 2.5 microM and Ki =21 x 10(-5) M at 5 microM). Furthermore, data on melanin biosynthesis indicated that the amount of melanin was clearly suppressed by 44'-BP.

Malignant melanoma of the sinonasal cavity: Explanation of magnetic resonance signal intensities with histopathologic characteristics

Purpose: To evaluate the magnetic resonance (MR) findings of malignant melanoma of the sinonasal cavity and compare these findings with those of the histopathological examination. Materials and Methods: The MR images of 11 patients with malignant melanoma of the sinonasal cavity were retrospectively reviewed. Ten patients had primary malignant melanoma of the sinonasal cavity and one had a local recurrence. The imaging findings were evaluated with special attention given to the signal intensity of the tumor, internal characteristics, and growth pattern on MR. Signal intensity and enhancement patterns of the tumors were compared with the histopathological findings. Results: On T1-weighted image, 6 tumors were hyperintense (5 melanotic and one amelanotic melanoma), and 5 tumors were isointense or hypointense (4 amelanotic and one melanotic). On T2-weighted images, 2 amelanotic tumors showed hyperintensity, and 5 melanotic tumors showed hypointensity. Four tumors (one melanotic and 3 amelanotic) were isointense. Four of the 7 tumors with hyperintensity on T1-weighted images showed patchy, higher-signal intensity areas. In 3 of them, patchy areas of a higher degree of pigmentation were found on histopathological examination. There were multiple linear dark signal intensities on T2-weighted images and/or linear-enhancing areas on enhanced T1-weighted images within the masses in 5 of the 11 patients. These findings could be explained as intratumoral vessels in 4 tumors and fibrous septa in one tumor on histopathological examinations. Conclusion: Malignant melanoma of the sinonasal cavity shows characteristic MR signal intensity, which is mainly attributable to the degree and distribution of melanin pigmentation, and partly attributable to hemorrhage within the mass. The linear, low-signal intensity on T2-weighted images or enhanced lines are intratumoral vessels or fibrous septa. (Am J Otolaryngol 2000;21:366-378. Copyright © 2000 by W.B. Saunders Company)

An Electron Microscopic Study of Melanin in the Hair and Hair Follicles

The distribution of melanin pigment in all black guinea-pig hairs and anagen hair follicles was studied with the electron microscope. Melanocytes were identified in the upper part of the hair bulb, the outer root sheath and in the dermis adjacent to the follicle. In the immature medullary and cortical cells large numbers of melanosomes were seen among the other cytoplasmic structures. The cuticle cells contained a few melanosomes. As the different cell lines matured and underwent keratinization the melanosomes became embedded in the keratin. In the cortical cells the melanosomes were surrounded by a dense amorphous material which at many sites was attached to the inner surface of the plasma membrane. No melanin was seen in the cells of the inner root sheath. In the upper part of the outer root sheath the distribution of melanin closely resembled that found in the epidermis. In the lower part of the sheath the majority of the cells contained only a small amount of melanin pigment.

An Electron Microscopic Study of Melanin in the Hair and Hair Follicles

The distribution of melanin pigment in all black guinea-pig hairs and anagen hair follicles was studied with the electron microscope. Melanocytes were identified in the upper part of the hair bulb, the outer root sheath and in the dermis adjacent to the follicle. In the immature medullary and cortical cells large numbers of melanosomes were seen among the other cytoplasmic structures. The cuticle cells contained a few melanosomes. As the different cell lines matured and underwent keratinization the melanosomes became embedded in the keratin. In the cortical cells the melanosomes were surrounded by a dense amorphous material which at many sites was attached to the inner surface of the plasma membrane. No melanin was seen in the cells of the inner root sheath. In the upper part of the outer root sheath the distribution of melanin closely resembled that found in the epidermis. In the lower part of the sheath the majority of the cells contained only a small amount of melanin pigment.

The Relationship of Skin Color to Zygosity in Twins

The study of identical twins has been used in many fields of clinical research to help delineate the relative importance of genetic and environmental factors in the pathogenesis of disease. The literature on various dermatoses occurring in twins is extensive and has been reviewed elsewhere (1); however, the twin method has been used very little in the investigation of human pigmentation. The color of human skin, hair, and eyes is largely dependent upon the amount of melanin synthesized in melanocytes. The presence of these cells in the basal layer of the epidermis represents the endpoint of a migration from the neural crest which probably occurs before the end of the third month of fetal life. The distribution of melanocytes in human skin has been the subject of intense investigation in recent years, Szabo (2) showed that the presence of melanocytes in all skin areas is independent of exposure to sunlight or covering with clothes. Staricco and Pinkus (3) and Szabo (2) have studied the distribution of melanocytes in different races and compared melanocyte counts in various areas of the body. There are no significant racial differences in number or distribution of melanocytes. The differences in color between races, and between individual subjects, are due to variations in the quantity and distribution of melanin pigment within the melanocytes. Two hormones, alpha- and beta-melanocyte stimulating hormones (a- and /?-MSH), which may be important regulators of skin color in man (4) have been isolated from the pituitary gland. These investigations have in turn aroused new interest in the role of genetic and non-genetic factors in human pigmentation.

Coat color genes in rodents and carnivores.

INTRODUCTION A NY comparative review of coat color genes in mammals faces unavoidable difficulties. Only a few species have been studied sufficiently to provide enough information for accurate analysis on which genetic similarities or differences between species can be determined. There are at least four types of evidence that will help to estimate the probability of interspecific homology of genes. These will be referred to in discussion of loci in each group. These types of evidence are as follows: (1) similar linkage relations between two or more genes; (2) similar pleiotropic effects of genes; (3) similarity of multiple allelic series; and (4) similar morphogenesis and function of melanoblasts. The interspecific homology of genes or loci will, however, remain to some degree uncertain unless direct evidence from interspecific crosses is available. It seems proper, therefore, to list under each species the genes and loci recorded in it, and later to discuss under the loci the points of similarity and dissimilarity which comparison between species reveals. There seems to be little question that the basic chemical processes underlying melanin pigment formation are similar in rodents and carnivores. It is undoubtedly more than a coincidence that three, and only three, pigments (yellow, brown, and black) are found in the coats of each group. It is also important to note that in all the species observed yellow pigment formation and distribution may, under certain conditions, be affected by genes, independently of the brownblack pigments. The opposite is also true, and one finds genes which appear to act only on brownblack and not on yellow. To a large degree also the basic origin and morphogenesis of melanoblasts appear to be the same in both groups. There may be in carnivores (at least in the Felidae) a skin pattern involving structural differences which is a phenomenon absent or as yet unrecorded in rodents. This condition has been described in the domestic cat by Pocock (1907), who noted that the black bands in striping and blotching were underlined by thicker skin than were the areas which remained light (tawny) as the pigment developed. The presence of skin areas of this type may be the reason for the so-called ghost patterns which sometimes appear in newborn or young black animals and which disappear during the uniform distribution of dark pigment or by the replacement of the juvenile dark pigment by yellow at a later age. This matter will be further discussed when the color genes of cats and dogs are considered. Over a number of decades, efforts have been made to utilize genetic experimentation to help to elucidate the chemical and morphogenetic factors and processes underlying the formation and distribution of melanin pigment in mammals. In genetic studies, the house mouse has had the longest and most important role. From the obviously primitive efforts of the writer (1913) to classify coat color genes, through the much improved analysis by Wright (1917), and up to the

MELANIN IN THE INNER EAR

REVIEW OF LITERATURE The presence and distribution of melanin pigment in the labyrinth has long been recognized. In recent years, however, this fact has been overlooked by the authors of general textbooks of histology in their discussions of both pigment and the cytologic structures of the inner ear. English textbooks, in particular, have been remiss in this respect. In 1851, Corti described pigment cells, resembling those of the choroid coat of the eye, in the "periosteum" (spiral ligament) of the cow and sheep. He observed pigment in amorphous grains and in enlarged epithelial cells of the stria in "very old" cats. It was also noted along the aqueduct of the cochlea and, in the cow and sheep, along the sheath of the auditory nerve. As early as 1860, Voltolini of Breslau, in the first of a series of three reports on postmortem conditions of human ears, cited the presence