China
Africa
Explore chapters and articles related to this topic
Synthetic Compounds vs. Phytochemicals for the Treatment of Human Cutaneous Malignant Melanoma
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
Jacqueline Maphutha, Namrita Lall
The skin is composed of three main layers: the epidermis, dermis and hypodermis. The epidermis is the outer layer of the skin that serves as a physical and biological barrier to the external environment, e.g. protection from ultraviolet radiation and allergens. The epidermis is made up of five layers, namely the stratum corneum, stratum lucidum (found where the skin is the thickest i.e. palms and soles of feet), stratum granulosum, stratum spinosum and stratum basale. The dermis, which is thicker than the epidermis, sustains and supports the epidermis, while the hypodermis consists mainly of fat that supports the skin and insulates the body from cold and shock (Lawton, 2019). Melanocytes are distributed in the stratum basale layer of the epidermis and melanin (produced by melanocytes) displays photoprotective effects through the absorption of UV radiation. However, the exposure of the skin to excessive UV radiation, especially UVB radiation (280–315 nm), which cannot be absorbed by melanin, results in mutagenesis in melanocytes leading to HCMM (Lawton, 2019).
Exploring the Plant Kingdom for Sources of Skincare Cosmeceuticals
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Wild Plants, 2020
Mayuri Napagoda, Sanjeeva Witharana
The skin is the outer covering of the human body and is considered as the largest organ in a human. It is comprised of three major structural layers viz., epidermis, dermis, and hypodermis (Tabassum and Hamdani 2014). The epidermis is the outermost layer of the skin which encompasses five sub-layers/strata; stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. The dermis lies beneath the epidermis and is attached to an underlying hypodermis or subcutaneous connective tissue (Tabassum and Hamdani 2014).
Isolated Perfused Skin Flap and Skin Grafting Techniques
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
J. Edmond Riviere, Michael P. Carver
The pig is well accepted as an animal model for percutaneous absorption studies.13,44,60–64 Pig and human skin have a similar gross appearance, a sparse hair coat, a relatively thick epidermis compared to other laboratory animal species, a similar microstructure, comparable microcirculation, and similar arrangements of dermal collagen and elastic fibers. Differences in morphology primarily relate to the nature and distribution of the sweat glands.65–72 Biochemically, cutaneous enzyme histochemistry, carbohydrate and fatty acid metabolism, and lipid composition are also comparable.73–77 The rate of epidermal turnover in both species ranges from 26 to 30 days.78 Of critical importance to skin flap techniques, the skin of the ventral abdomen of pigs is supplied by the superficial epigastric artery, making this species ideally suited for developing an isolated skin flap model.
Transport of hydrocortisone in targeted layers of the skin by multi-lamellar liposomes
Published in Journal of Liposome Research, 2023
Antoine Bernasqué, Muriel Cario, Stéphanie Krisa, Sophie Lecomte, Chrystel Faure
Targeting a specific layer of the skin can be considered the grail for the pharmaceutical and cosmetic industry. Targeting the stratum corneum (SC) would allow e.g. restructuring it in pathologies where skin hydration is affected (Menon et al.2012, Pischon et al.2017), to protect it from oxidative damage (Thiele, 2001), or to prevent the entry of certain pathogens into the body (Lipsky et al.2020). Many diseases such as atopic dermatitis or melanoma originate from dysfunctions within the epidermis. Topical treatment of these diseases can cause side effects due to the passage of the active ingredient into the bloodstream. Targeting the epidermis could avoid this (Hemrajani et al.2022, Krishnan and Mitragotri 2020). Epidermis-restricted delivery of an active molecule represents a promising strategy for blood transfer diminution, drug efficiency improvement and/or drug concentration diminution into commercial products. Conversely, reaching the systemic circulation topically has advantages over oral administration by minimising metabolism, and avoiding the unfavourable gastrointestinal environment, which are responsible for the low bioavailability of many drugs, and by promoting a prolonged drug administration (Payne et al.1998).
Shedding light on key pharmacological knowledge and strategies for pediatric atopic dermatitis
Published in Expert Review of Clinical Pharmacology, 2023
Ariana Moreno, Yael Renert-Yuval, Emma Guttman-Yassky
The epidermis plays a critical role in both physical and chemical barrier. A pathognomonic finding in AD is a disrupted epidermal barrier resulting in increased trans epidermal water loss (TEWL) [1]. AD-related barrier defects include terminal differentiation abnormalities (e.g. decreased levels of filaggrin/FLG and loricrin/LOR), claudin defects (e.g. downregulation of CLDN1 and CLDN5), and aberrant lipid metabolism in the stratum corneum (e.g. lower levels of very long chain fatty acids protein 3/ELOVL3 and fatty acid 2-hydroxylate /FA2H), in both adult and pediatric AD [6,9,10]. However, infant AD presents greater alterations in lipid genes related with the epidermal barrier, while adult AD presents more extensive downregulations of terminal differentiation genes in skin biopsies, among other variations detected across various age-groups [10].
Occupational exposure assessment with solid substances: choosing a vehicle for in vitro percutaneous absorption experiments
Published in Critical Reviews in Toxicology, 2022
Catherine Champmartin, Lisa Chedik, Fabrice Marquet, Frédéric Cosnier
As shown in Figure 1, the epidermis is a coating epithelium. The viable epidermis, with a thickness varying roughly from 30 to 100 µm, consists of the stratum basale, the stratum spinosum, and the stratum granulosum (SG). It is separated from the dermis by the basement membrane. The viable epidermis is innervated but not vascularized, and its nutritional needs are met through diffusion from the basement membrane. One of its functions is as a barrier against environmental aggression. The majority (80%) of epidermal cells are the keratinocytes; the other cell types found in the epidermis are melanocytes, Langerhans cells, and Merkel cells. Specialized junctions called corneodesmosomes or desmosomes (to which the tonofilaments are tethered) (Prost-Squarcioni 2006) link keratinocytes together and contribute to the outside-in epidermal barrier. The highly protective outermost layer of the epidermis – the stratum corneum (SC) – is constantly renewed. It is about 10–40 µm thick and composed of 15–25 layers of corneocytes, i.e. dead and keratinized cells resulting from the terminal differentiation of keratinocytes that have migrated to the skin’s surface.