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Pharmacokinetics of Nanomaterials/Nanomedicines
Published in Yasser Shahzad, Syed A.A. Rizvi, Abid Mehmood Yousaf, Talib Hussain, Drug Delivery Using Nanomaterials, 2022
Mulham Alfatama, Zalilawati Mat Rashid
The permeation of a particle in TDD system is likely to occur through three possible pathways which are the intercellular, transcellular, and transappendageal pathways (Figure 3.1). A particle possibly permeates via a combination of these routes, depending on the physiochemical properties of the molecule (Alexander et al. 2012; Desai, Patlolla, and Singh 2010). The intercellular pathway involves diffusion through the continuous lipid domains occupying the keratinocytes intercellular spaces. This pathway presents a significant challenge as a drug must successively permeate into and diffuse through the due to the “brick and mortar” arrangement and the stratified bilayers nature of the intercellular domain structure. This is generally acknowledged as the common permeation route of small uncharged molecules (Gandhi et al. 2012). The transcellular pathway involves diffusion through dead keratinocytes, the corneocytes. The corneocytes highly hydrate keratins provide an aqueous condition for the hydrophilic drug to pass through the skin after several partitioning and diffusion steps which eventually affect the drug bioavailability. The transappendageal pathway (shunt route) involves penetration across the skin hair follicles, sebaceous glands, and sweat glands. Despite providing a continuous channel directly across the stratum corneum, the appendageal pathway is constricted by the appendages small surface area (commonly 0.1% of surface area of the skin), thus limiting the spaces available for the drug application (Alexander et al. 2012).
Role of Nanotechnology in Tissue Engineering and Regenerative Medicine
Published in Jyoti Ranjan Rout, Rout George Kerry, Abinash Dutta, Biotechnological Advances for Microbiology, Molecular Biology, and Nanotechnology, 2022
Bijayananda Panigrahi, Uday Suryakanta, Sourav Mishra, Rohit Kumar Singh, Dindyal Mandal
The stratum corneum, the outmost layer of keratinized cells, called corneocytes, also a precise skin defensive barrier which is the combination of intracellular lipid and crystalline gel structure, plays the role of mortar between the corneocytes. It is extremely dynamic in lipid enzymatic synthesis and has the capability to acclimate to the environment (Elias and Menon, 1991). Defects are formed by harshly injured skin, which is caused by huge burns or constant wounds. These defects alter the synthesis of the extracellular matrix (ECM) and therefore obstruct the skin’s ability to respire, preserve or drive out water, and defend it against the harmful pathogen, oxidants, and toxins. Therefore, the main function of stratum corneum is to protect from external damage. Skin represents itself as the first layer of defense and also as a boundary wall of the body’s organs. When the skin is injured beyond a certain limit of the total body area, death may result from such damage. Therefore, it is very necessary to immediately cover with dressing which could save from losing the integrity of tissue, homeostasis level, and prevents from toxic materials along with pathogens. The four main objectives that should be cared of a burnt wound are the following: (1) avoid infection, (2) controlling the moist environment around the wound, (3) protect wounds from external aggressions, and (4) reduction of scar formation (Elias and Menon, 1991).
Biology of the Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Future developments regarding skin and hair conditioning agents rely on a better understanding of the biology of these structures. Only by elucidating mechanisms for enhanced growth and repair can product development occur. A wealth of information on the mechanisms of skin barrier formation is accumulating, leading to the realization that many disease states (atopic dermatitis, xerotic eczema) may be due to faulty sebum production and/or improper formation of the intercellular lipids. Future dermatological research may find a topical method of replacing missing substances and restoring normal function. A better understanding of defective corneocyte sloughing encountered in mature individuals is leading to the development of topical moisturizers designed to increase desquamation and restore a smooth skin surface.
Genetic variants affecting chemical mediated skin immunotoxicity
Published in Journal of Toxicology and Environmental Health, Part B, 2022
Isisdoris Rodrigues de Souza, Patrícia Savio de Araujo-Souza, Daniela Morais Leme
The FLG monomers take part in SC formation. In this process, FLG monomers bind to keratin filaments, aggregating them into keratin fibrils organized in parallel bundles to form a matrix that provides rigidity to the overall structure, which are the major constituents of corneocytes (Egawa and Kabashima 2018; Norlén and Al-Amoudi 2004). Corneocytes generate a network within a lipid-rich extracellular matrix and produce compaction of keratinocytes. In the process of compacting keratinocytes, corneocytes are denucleated and flattened, and the intercellular space between them filled with lipids from the lamellar bodies (Egawa and Kabashima 2018). Lamellar bodies are membrane-circumscribed granules produced by keratinocytes from SG and contain lipids, corneodesmosin, and kallikreins (Egawa and Kabashima 2018). These lipids are mainly ceramides, free fatty acids, and cholesterol. The secretion of the content of lamellar bodies into the extracellular space enables the covalent attachment of o-hydroxylated ceramides and fatty acids to cornified envelope proteins, forming a lipid-bound envelope (Hill, Paslin, and Wertz 2006). Then, lysosomal enzymes, which need an acidic pH optimum, degrade the polar lipid precursor to hydrophobic ceramides, generating an intact permeability barrier, and is responsible for the acidic pH of the skin (Doering et al. 1999).