Melanotropic Peptides: Biomedical Applications
Mac E. Hadley in The Melanotropic Peptides, 2018
The human skin is populated by pigment cells, melanocytes, whose function is to produce melanin. Melanin provides a sunscreen to protect the skin from the harmful (cancer-producing) rays of the sun. Sun tanning is, in fact, an adaptive response in which these pigment cells produce even more melanin to protect the skin under conditions of continued solar exposure. Unfortunately, these pigment cells are themselves vulnerable to the mutagenic (carcinogenic) actions of solar (ultraviolet) radiation. Melanocytes are converted into cancer cells, specifically, melanoma cells. Melanoma cells proliferate to form tumors in the skin, but then melanoma cells almost invariably metastasize to other parts of the body. Early surgical removal is important, since chemotherapeutic treatment strategies are presently ineffective in eradicating the cancer.
LIQUID AIR
Rob Norman in The Woman Who Lost Her Skin, 2004
The skin has three major components: the epidermis, dermis, and subcutaneous layers. The epidermis, the outermost layer of skin, has a top layer called the stratum corneum, composed of closely-packed cells which helps protect the skin from external abuse. Underneath are pigment cells, which provide our variation in color, and immune cells, which filter out foreign materials and dangerous substances. The middle layer is the dermis, where collagen, blood vessels, nerves, and other substrates live. Below the dermis is the fatty subcutaneous layer, which protects and insulates. When you're a baby, your skin is elastic and resilient, and it changes every day from then on. We lose about 1% of collagen every year after age thirty, as well as elastic fibers and blood vessels that attach to the epidermis. The result is crinkles and wrinkles - a rather unfair exchange. The skin becomes sallow and pale. We increase fat deposition in the areas we don't like, and we lose fat and therefore insulation in other body areas such as the face, arms, and legs, which decreases our tolerance for cold. The underlying tissue depletion makes us more prone to injury, and the loss of nerves provides for poor heat tolerance. Now, on top of all these natural occurrences of aging, consider increased exposure to UV light, alcohol, smoking, diet, and heredity. The protective ozone layer is thinning, and skin cancer rates are increasing. In the United States one person dies every hour from skin cancer; one third of all
Actions of Dopamine on the Skin and the Skeleton
Nira Ben-Jonathan in Dopamine, 2020
The base of the hair follicle, the hair bulb, contains cells that divide and grow and build the hair shaft (Figure 11.9A). Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life. The bulge is located in the outer root sheath at the insertion point of the arrector pili muscle. The arrector muscles contract in response to cold or fear, making the hair stand up straight. The bulge houses several types of stem cells, which supply the entire hair follicle with new cells and take part in healing the epidermis after a wound. Hair grows at different rates in different people; the average rate is around one-half inch per month. Hair color is created by pigment cells producing melanin in the hair follicle. With aging, pigment cells die, and hair turns gray.
Anatomical structure, and expression of CCL4 and CCL13-like during the development of maxillary barbel in Paramisgurnus dabryanus
Published in Organogenesis, 2019
Kianann Tan, Ruijing Geng, Zhiqiang Wang, Han Liu, Weimin Wang
The maxillary barbels of adult P. dabryanus were stained by Masson trichrome and cut into longitudinal and transverse sections, respectively. Through histological observation of maxillary barbels (transverse section), we found that the components building up the barbels are taste buds, blood vessels, a nerve bundle, collagen fiber, epithelium, loose connective tissue, pigment cells, cartilage rod, muscle fibers, and goblet cells (Fig. 2). The outer layer is a thick layer of epithelium, dense in taste buds and goblet cells. The inside layer of the epithelium is a dermis layer and has a dense layer of collagen fiber, few blood vessels, and few nerve bundles. In the dermis layer, some pigment cells such as melanocytes can be found. The cartilage rod (or ‘central rod’) is located in the central region of the barbels. The cartilage rod is covered in a thick layer of loose connective tissue. The outside layer of loose connective tissue is a dense layer of muscle fiber. From histological observation, we can see P. dabryanus has a vast number of nerve bundles in the barbels, and muscle fiber is surrounded by a layer of nerve bundles.
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].
Postinflammatory hypopigmentation: a comprehensive review of treatments
Published in Journal of Dermatological Treatment, 2022
Pamela N. Madu, Nicole Syder, Nada Elbuluk
Postinflammatory hypopigmentation occurs secondary to an intrinsic or external insult to the skin. A thorough clinical history is essential to diagnosing this condition and identifying the underlying cause. The pathogenesis of PIH has not been fully elucidated. Proposed mechanisms include decreased melanin production, blocked transfer of melanosomes to keratinocytes, and melanocyte loss (14). Histopathological studies suggest that suppression of melanogenesis serves a primary role in postinflammatory hypopigmentation as opposed to melanocyte loss (1,14). In a theory known as ‘individual chromatic tendency’, Ruiz et al. proposed a genetic predisposition toward hyperpigmentation or hypopigmentation through the inheritance of ‘strong’ and ‘weak’ melanocytes, respectively (15). They purport that ‘weak’ melanocytes are easily damaged in response to inflammation leading to hypopigmentation, and ‘strong’ melanocytes are more likely to respond with hyperpigmentation (15). Since the emergence of this theory, there have been no countering theories or additional studies to evaluate this hypothesis further.
Related Knowledge Centers
- Epidermis
- Eye
- Inner Ear
- Meninges
- Neural Crest
- Stratum Basale
- Uvea
- Melanin
- Cell
- Vaginal Epithelium