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Conducting Polymer-Based Nanomaterials for Tissue Engineering
Published in Ram K. Gupta, Conducting Polymers, 2022
Murugan Prasathkumar, Chenthamara Dhrisya, Salim Anisha, Robert Becky, Subramaniam Sadhasivam
Skin is the largest organ in the human body and covers a distance of 1.8–2.0 m2 and is composed of epidermis, dermis, and hypodermis. The epidermis contains stem cells, and it will induce self-regeneration once the wound occurred. A severe wound or burns result in a chronic or nonhealing wound with delayed recovery, and the loss of full skin more than 4-cm diameter needs skin grafting. Surgical options are limited due to the lack of donors, and foreign grafts often exert immune rejection and infection. Hence, tissue-engineered skin substitutes are recommended to overcome the drawbacks. The skin was the first organ that went from laboratory research to patient care among the various engineered organs. Tissue engineering is rapidly evolving to find a better skin substitute that can be efficiently used for clinical applications [21].
Nanomaterials in the Work Environment
Published in Małgorzata Pośniak, Emerging Chemical Risks in the Work Environment, 2020
Lidia Zapór, Przemysław Oberbek
Skin is the largest human organ, with a surface area of about 1.5–2 m2. As shown in Figure 2.3, it is composed of three layers, from the outermost layer: the epidermis, dermis, and subcutaneous tissues. The epidermis is composed of five layers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. The stratum corneum is composed of tightly connected terminally differentiated cells (corneocytes) and is a natural barrier of the body. This barrier can be easily weakened by, for example, mechanical damage (abrasions), inflammation, exposure to UV radiation, or microbial colonization. Experimental studies to date show that only very small particles, below 4 nm, are capable of entering the surface channels between corneocytes and pass through undamaged skin. Flexible ENMs, such as liposomes and micelles, are an exception, as they are capable of penetrating undamaged skin even with sizes above 4 nm. The most likely way of nanoparticle absorption is through the hair follicles, sebaceous glands, and sweat glands. This is the most effective way of absorption for particles in the 4–20 nm range. The penetration of particles in the 20–45 nm range has only been observed when the skin is damaged, while non-soluble particles above 45 nm did not even pass through damaged skin [Larese Filon et al. 2015; 2016; Wang et al. 2018].
Treatment of Pressure Sores
Published in J G Webster, Prevention of Pressure Sores, 2019
Granulation tissue consisting of a dense population of macrophages, fibroblasts, and neovasculature embedded in a loose matrix of collagen and other substances appears (Clark 1988). Figure 14.2(b) shows the granulation tissue beginning to form. As collagen fibers become more organized, the tensile strength of the wound increases (Torrance 1983). New blood vessels grow (angiogenesis) as in figure 14.2(c) and infiltrate the wound simultaneously with the fibroblast and neomatrix components of the granulation tissue (Clark 1988). The new vessels form to nourish the tissues and always originate from existing vessels, beginning as capillary buds (Hunt and Van Winkle 1979). Epithelialization, the migration of cells that cover all the free surfaces of the body, takes place to regenerate the epidermis. Once the epithelial cells begin to migrate, they lose their ability to divide. Therefore, epithelial cells must migrate from areas with undamaged epithelial cells: bases of viable hair follicles, sebaceous glands, sweat glands, or wound margins. The infiltration of new blood vessels and tissues from the wound margin leads to the contraction of the wound (Barton and Barton 1981).
Shielding response of rodent skin to water soluble ambient air pollutants
Published in Journal of Environmental Science and Health, Part A, 2020
Chun-Tang Chiu, Fen-Pi Chou, Ting-Shuan Yu
The epidermis forms a critical barrier to shield the body from environmental insults. Epidermal hyperplasia is a hallmark feature for some diseases, such as atopic dermatitis and psoriasis. [13] However, the pathological change could be the effect caused by the inflammatory stimuli from the inside of body. The epidermal thickness has been reported to be increased markedly after a topical application of 40 mg of lauroyl peroxide or benzoyl peroxide on the rodent mice, while no major inflammatory or vascular alterations were noted. [14] Retinoids widely used for the treatment of numerous dermatological disorders improve dermal functions and concurrently induce epidermal hyperplasia, which can lead to excessive scaling. [15] The thickening of epidermis observed in this study by the application of air pollutants with different complexity and concentration without triggering inflammatory response could be considered as the protective function of the skin preventing air-borne environmental insults entering into dermis, as we found that the more concentrated air pollutants (WSAP72h) was toxic to skin fibroblast. Nevertheless, a disruption in the skin shielding function by a prolonged and repetitive exposure to environmental pollutants that surpasses the skin’s normal defensive ability will lead to the development of various skin diseases. [7]
Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Jin Ju Park, Junmin An, Jung Dae Lee, Hyang Yeon Kim, Jueng Eun Im, Eunyoung Lee, Jaehyoun Ha, Chang Hui Cho, Dong-Wan Seo, Kyu-Bong Kim
The skin is a protective outer covering extending throughout the human body which protects internal tissues and organs. Human skin is composed of three primary layers; the epidermis, dermis, and hypodermis. The epidermis, the outermost layer of the skin, functions by protecting the body and is predominantly composed of keratinocytes, melanocytes, Langerhans, and Merkel cells. Keratinocytes are the most abundant cells found in the epidermis and function as a barrier against the external environment (McGrath, Eady, and Pope 2004; Winkelmann and Breathnach 1973). Melanocytes produce the colored pigment of melanin. Melanin occurs in two forms in human skin: eumelanin and pheomelanin. Eumelanin is black and brown melanin and common throughout the body, while pheomelanin is a red or yellow melanin pigment (Wakamatsu and Ito 2002). Melanin is biosynthesized from tyrosine. Tyrosine is converted to DOPA (3,4-dihydroxy-L-phenylalanine), which is then oxidized to DOPA-quinone and subsequently converted to DOPA-chrome. Melanin is finally generated through several intermediates and a series of biochemical steps. Tyrosinase plays a key role in the melanin biosynthetic pathway by converting tyrosine to DOPA (Choi et al. 2001; D’Mello et al. 2016; Kong et al. 2000). The inhibition of tyrosinase leads to blockade of melanin production. The reaction of tyrosinase (activity or inhibition) with test material is used as a measure of efficacy of the compound. Melanin, which is synthesized and matures in the melanosome, is transferred to keratinocytes where pigmentation occurs. Skin color is determined by melanin in the melanocytes. Melanocytes function predominantly by producing melanin pigment, which protects against and absorbs harmful ultraviolet (UV) radiation (D’Mello et al. 2016).
Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Jin Ju Park, Junmin An, Jung Dae Lee, Hyang Yeon Kim, Jueng Eun Im, Eunyoung Lee, Jaehyoun Ha, Chang Hui Cho, Dong-Wan Seo, Kyu-Bong Kim
The skin is a protective outer covering extending throughout the human body which protects internal tissues and organs. Human skin is composed of three primary layers; the epidermis, dermis, and hypodermis. The epidermis, the outermost layer of the skin, functions by protecting the body and is predominantly composed of keratinocytes, melanocytes, Langerhans, and Merkel cells. Keratinocytes are the most abundant cells found in the epidermis and function as a barrier against the external environment (McGrath, Eady, and Pope 2004; Winkelmann and Breathnach 1973). Melanocytes produce the colored pigment of melanin. Melanin occurs in two forms in human skin: eumelanin and pheomelanin. Eumelanin is black and brown melanin and common throughout the body, while pheomelanin is a red or yellow melanin pigment (Wakamatsu and Ito 2002). Melanin is biosynthesized from tyrosine. Tyrosine is converted to DOPA (3,4-dihydroxy-L-phenylalanine), which is then oxidized to DOPA-quinone and subsequently converted to DOPA-chrome. Melanin is finally generated through several intermediates and a series of biochemical steps. Tyrosinase plays a key role in the melanin biosynthetic pathway by converting tyrosine to DOPA (Choi et al. 2001; D’Mello et al. 2016; Kong et al. 2000). The inhibition of tyrosinase leads to blockade of melanin production. The reaction of tyrosinase (activity or inhibition) with test material is used as a measure of the efficacy of the compound. Melanin, which is synthesized and matures in the melanosome, is transferred to keratinocytes where pigmentation occurs. Skin color is determined by melanin in the melanocytes. Melanocytes function predominantly by producing melanin pigment, which protects against and absorbs harmful ultraviolet (UV) radiation (D’Mello et al. 2016).