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Disorders of Pigmentation
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Michael Joseph Lavery, Charles Cathcart, Hasan Aksoy
Overview: Melanocytes are dendritic cells derived from the neural crest. They are located in the basal layer of the epidermis but may also be observed in the eye, inner ear and leptomeninges of the brain. Melanocytes serve three important functions: production of melanin, protection from ultraviolet-associated mutations, and absorption of ultraviolet radiation (UVR).
Animal Source Foods
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
In humans, the main pigment is black melanin which is found in skin, hair, eye iris, inner ear (stria vascularis), brain (substantia nigra), and adrenal gland (zona reticularis) (5–7). Black melanin in humans is able to dissipate over 99.9% of absorbed UVB radiation of sunlight, therefore it is thought to protect skin cells from solar radiation damage, reducing the risk of skin cancer or melanoma (5–7). However, UVB of sunlight is also necessary for the production of vitamin D3 that is formed from cholesterol in the skin under the action of sunlight. Too much melanin in the skin will stop the production of vitamin D3 due to the absence of UVB of sunlight. The black color of melanin is predominant; melanin hides other colors. When this black pigment is absent, other colors like white, blue or yellow will appear and, therefore skin, eyes, hair becomes white, blue, or blonde, respectively. Melanin is produced by a melanocyte which is located in the skin, hair, and eyes. It is noteworthy that the colors of the skin and hair are not related to the intelligence of an individual or a human race. A person’s intelligence comes from their genes and brain. In brief, the color of human skin plays important roles in the protection of excess UVB from sunlight and the synthesis of vitamin D3 in the skin. This means that the absence of melanin in the skin may engender skin cancer and its excess can cause vitamin D3 deficiency.
Melanoma
Published in Debjani Sahni, Adam Lerner, Bilal Fawaz, Advanced Skin Cancer, 2022
Melanoma is a skin cancer originating from melanocytes that are most commonly located in the skin. Melanoma can less commonly also arise from the eye or mucosal surfaces of the head and neck, urogenital tract, and gastrointestinal surfaces.1 Melanoma is responsible for more than 90% of deaths related to skin cancer, with incidence increasing by 270% from 1973 to 2002 in the United States.2,3
Deep learning-based fully automated diagnosis of melanocytic lesions by using whole slide images
Published in Journal of Dermatological Treatment, 2022
Yongyang Bao, Jiayi Zhang, Xingyu Zhao, Henghua Zhou, Ying Chen, Junming Jian, Tianlei Shi, Xin Gao
According to the World Health Organization (WHO), skin cancer accounts for one-third of cancers worldwide (1). The global incidence of skin cancer has continued to increase in the last 20 years (2). Melanoma is the most fatal skin cancer (3); it is characterized by malignant melanocytic lesions, is associated with early metastasis, and has a high degree of mortality (4). Patients diagnosed with malignant melanocytic lesions require surgery combined with other treatments such as radiation therapy, chemotherapy, interferon therapy, or immunotherapy. Conversely, those diagnosed with atypical or benign melanocytic lesions need surgery and careful clinical observation or a single surgery. Thus, the early and accurate diagnosis of melanocytic lesions is vital for determining the optimal clinical treatment and improving patient prognosis (5).
Antibacterial, Antioxidant and Melanogenesis Inhibitory Activity of Auraptene, a Coumarin from Ferula szowitsiana Root
Published in Nutrition and Cancer, 2022
Ensiyeh Charmforoshan, Ehsan Karimi, Ehsan Oskoueian, Mehrdad Iranshahi
The melanin production process (melanogenesis) takes place in cells known as melanocytes. Melanin production is necessary for skin pigmentation against UV irradiation. On the other hand, the increased production of melanin might cause several skin disorders including lentigines, nevus, freckles, melisma, and age spots. Kojic acid, linoleic acid, arbutin are tyrosinase inhibitors and used for the treatment of hyperpigmentation. Generally, the skin-whitening agents are tyrosinase inhibitors possessing toxicity against melanocytes and indicated adverse side effects. Thus, the development of natural tyrosinase inhibitors with low toxicity is necessary (28). In the present experiment, auraptene isolated from Ferula szowitsiana root possessed high inhibitory activity against tyrosinase enzyme with the IC50 values of 29.7 μg/mL however this value was lower than that of kojic acid as a reference standard with a respective IC50 value of 14.7 μg/mL (Figure 5).
Development of piperine nanoemulsions: an alternative topical application for hypopigmentation
Published in Drug Development and Industrial Pharmacy, 2022
Burcu Ozkan, Ebru Altuntas, Rabia Cakir Koc, Yasemin Budama-Kilinc
Melanin biosynthesis is a complex mechanism that occurs within melanocytes, very specialized pigment cells within membrane-bound organelles called melanosomes [1]. Melanogenesis has different stages, and when this process is disrupted, different types of pigmentation disorders can be seen, classified as hypo- or hyperpigmentation [2,3]. Melanocytes are largely destroyed in hypopigmentation disorders such as vitiligo due to the loss of functional epidermal melanocytes. Therefore, depigmented lesions occur on the skin [4]. Vitiligo is a common disease affecting 0.5–2% of the general population. This bothersome disease begins on average at the age of 20 but is most common between the ages of 10 and 30 [5]. This apparent disorder can lead to many psychological, social and physiological problems in individuals [6].