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Alginate and Hydrogel Applications for Wound Dressing
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Dina Fransiska, Ellya Sinurat, Fera Roswita Dewi, Hari Eko Irianto
Moreover, the skin performs many vital functions, including preventing water loss from the body, and it has a role in regulating body temperature. Normal human skin consists of three layers, including the epidermis, the dermis, and the hypodermis. The barrier function of the skin is provided by the epidermis, which is composed mainly of keratinocytes. They form a stratified epithelium, with basal keratinocytes at the innermost layer and the keratinized, relatively impermeable outer stratum corneum layer on the surface.
Dermal Hypersensitivity: Immunologic Principles and Current Methods of Assessment
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The immunophenotypic differences between irritant dermatitis and ACD have been recently compared in human skin samples. As expected with delayed-type hypersensitivity, mostly T lymphocytes were apposed to Langerhans’ cells, and few polymorphonuclear leukocytes infiltrated reaction sites during either irritant dermatitis or ACD in one study.57 In other studies damaged and fewer Langerhans’ cells were observed during irritant reactions, while more and translocated (from epidermis to dermis) Langerhans’ cells were seen during ACD.58–60 Natural killer cells and B cells were usually absent, and T helper/inducer cells predominated over T suppressor/cytotoxic cells for both types of reactions.60 Keratinocytes expressed HLA-DR antigens only during ACD and not during irritant contact dermatitis in another related study.61
Structure and Function of Human Skin
Published in Marc B. Brown, Adrian C. Williams, The Art and Science of Dermal Formulation Development, 2019
Marc B. Brown, Adrian C. Williams
Human skin is a remarkable barrier between the body and the environment, providing protection against ingress of allergens, chemicals, and microorganisms, regulating the loss of water and nutrients from the body and responding to mitigate the effects of ultraviolet (UV) radiation. The skin has an important role in homeostasis by regulating body temperature and blood pressure and is an important sensory organ for temperature, pressure, and pain. As the largest organ of the human body, providing around 10% of the body mass and covering an area of ~1.8 m2 in the average person, this easily accessible tissue apparently offers ideal multiple sites to administer therapeutic agents for both local and systemic actions, but human skin is a highly efficient self-repairing barrier that has evolved to keep “the insides in and the outside out”.
Histone deacetylase inhibitors as a potential new treatment for psoriatic disease and other inflammatory conditions
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Jehan Mohammad Nazri, Katerina Oikonomopoulou, Elvin D. de Araujo, Dziyana Kraskouskaya, Patrick T. Gunning, Vinod Chandran
Briefly, the human skin is composed of three layers: the epidermis, dermis, and subcutis. The epidermis is the topmost epithelial layer of the skin that is mainly composed of cells such as keratinocytes (skin cells that are also involved in psoriasis), melanocytes (cells responsible for producing a pigment called melanin), and Langerhans cells (immune cells for recognizing antigens). The dermis layer, also known as the supportive layer of the skin, consists of fibers such as collagen and elastin as well as cells like fibroblasts, neutrophils, lymphocytes, eosinophils, and monocytes. The subcutis, also called subcutaneous layer, is the fatty layer below the epidermis and dermis. Usually, in healthy, normal human skin, the presence of an invading foreign pathogen and/or allergen detected by cells in the epidermis and dermis will initiate a pro-inflammatory immune response via the activation of signaling pathways like the nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), Janus kinase/signal transducers and activators of transcription (JAK/STAT), and mitogen-activated protein kinase (MAPK) pathways [36]. Additionally, depending on what is required next for clearance of the foreign invasion, specific adaptive immune responses may also follow before resolution of the inflammation. However, when psoriasis is triggered, aberrant activation of the innate and adaptive immune responses follows and support the initiation as well as subsequent maintenance of psoriatic inflammation [37,38] (Figure 1).
Ginkgo biloba leaves extract’s cosmeceutical evaluation: a preliminary assessments on human volunteers towards achieving improved skin condition and rejuvenation
Published in Drug Development and Industrial Pharmacy, 2023
Ahmed A. H. Abdellatif, Hamdoon A. Mohammed, Ali M. Al-Khalaf, Omar Khan, Mahmoud A. H. Mostafa, Rwaida A. Al Haidari, Hesham H. Taha, Riaz A. Khan
The human skin is a complex structure and have multiple functions. The reasons for skin damage are vague, but modern theories have described it due to stopping certain biological systems’ proper functioning that is related to and consequential to the skin damage and loss of proper functioning, moistening as well as youthfulness [21]. The skin’s natural and environmentally-acquired damage is characterized by irregular pigmentation, drying, roughness, loss of elasticity, and wrinkles formation. Other reasons are unsubstantiated, and the damage is due to the accumulation of damaged DNA formed from irregular oxidations, DNA methylation processes, etc. Skin damage is also caused by genetic and environmental factors and exposure to chemicals leading to roughness, irregular pigmentation, and decreased skin elasticity [22,23]. Nowadays, most cosmetic skincare products are claimed to provide moisturizing, rejuvenating, youthfulness, glow, and skin health, and are recommended for prophylactic use. Most people prefer to use these skin products [24,25].
A method to predict burn injuries of firefighters considering heterogeneous skin thickness distribution based on the instrumented manikin system
Published in International Journal of Occupational Safety and Ergonomics, 2021
Epidermis, dermis and subcutaneous tissues are regarded as the three main layers of human skin. Heat transfer in the skin is a complex process including conduction combined with other physiological processes such as metabolic heat generation, blood perfusion and evaporation. Pennes bioheat transfer equation [6], based on Fourier’s law for conduction heat transfer, is frequently used to model skin heat transfer. Kumar et al. [7] dealt with the heat transfer in triple-layer skin tissue for three different types of surface heating using the time fractional bioheat model, which can describe dynamic events that occur in biological tissue. Zhai et al. [8] analyzed different mechanisms of steam diffusion through the multiple skin layers, as well as the moisture-assisted Pennes bioheat transfer. Various experiments were conducted on animals and human skin in order to investigate skin burns, which were associated with temperature evolution and exposure time [9,10]. According to the extent of burn injuries, burn wound depths are classified as first-degree, second-degree and third-degree burns. First-degree burns may be induced by sun exposure or hot liquids with low viscosity, which only involves the epidermis [1]. The dermis is involved in second-degree burns. Flame is one of the causes of third-degree burns, in which the full thickness of skin suffers thermal damage [1]. A classification of burns as superficial, superficial partial thickness, deep partial thickness and full thickness was also defined to reflect damage of the skin [11,12].