Epidermis layer

IA Melanoma in situ (involves only the epidermis layer) 1mm thickness, no ulceration and Clark level3 II or III 100% 100%... 

The stratum corneum consists of separated, nonviable, cornified, almost nonpermeable corneocytes embedded into a continuous lipid bilayer made of various classes of lipids, for example, ceramides, cholesterol, cholesterol esters, free fatty acids, and triglycerides [6], Structurally, this epidermis layer is best described by the so-called brick-and-mortar model [7], The stratum corneum is crucial for the barrier function of the skin, controlling percutaneous absorption of dermally applied substances and regulating fluid homeostasis. The thickness of the stratum corneum is usually 10-25 /an, with exceptions at the soles of the feet and the palms, and swells several-fold when hydrated. All components of the stratum corneum originate from the basal layer of the epidermis, the stratum germinativum. 

A typical dermal irritation assay is conducted as follows. Six male albino rabbits are be clipped free of hair on the back. One area of skin is left intact, whereas another is abraded in a tic-tac-toe pattern with the point of a hypodermic needle so as to incise the superficial epidermis layer without causing bleeding. The test material, 0.5 ml of liquid or 0.5 g of solid or semisolid is applied to each site under a 1 x 1 in. gauze pad. The entire trunk of the animal is wrapped with an impervious material and held in place with tape for 24 h. The patches are then removed and excessive material wiped off. The skin reactions are scored at 24 and 72 h after the initial application according to a scheme such as that listed in Table 2. 

Where is the area of the patch Qp, the concentration of drug in the patch R, the overall resistance and R, the resistance to release from the patch. There are a number of situations one can consider, such as the patch resistance limits the delivery, diffusion through the epidermis limits delivery, or the concentration of the drag is kept constant in the patch by using solid hydrogels. When diffusion through the epidermis layer limits, the rate of drug delivery rate is... 

A 25 s exposure is sufficient to cause a significant alteration of the morphology of all epidermis layers. [13] A strong acantholysis allows the formation, by areas, of suprabasal blisters at the base of the stratum comeum. In these areas. 

Even if it is a partially dissociated acid (p/fa=3.2), all safety managers and company doctors, toxicologists, as well as workers know what hydrofluoric acid (HE) can do on skin. It can induce more severe damages than all other strong acids. It is due to its double danger, corrosive because of the acidic (H ) ions and toxic because of the fluoride (F") ions that can bind cellular calcium and magnesium. H+ ions create a superficial destruction of the epidermis layer allowing F toxic ions to penetrate deeper in the skin [6, 257]. 

An activation photosensitizer, laser and relation color of hair appeared as a task factors to change photodynamic dose rate and this is one of the most challenging problems in the field of PDT for epidermis layer, both in terms of research and of development. Consideration of hair color during therapy will increase the quality of PDT treatment in patients. Our results demonstrated and concluded that the types of a hair color, concentration, and penetration depth into the skin affect the absorptive and scattering processes to impact photodynamic dose in PDT for superficial diseases. Computation simulation considerations show that the effect of hair of different colors is affecting light penetration and dose injection. 

Fig. 20. (a) Optical image of a self-healing sample containing a microvascular network substrate after crac are formed in the epoxy coating, showing the release of the healii agent from the cracks (Scale bar = 5 mm) (b) schematic diagram of a capillary network in the dermis layer of skin with a cut in the epidermis layer. Reprinted from K.S. Toohey, N.R. Sottos, J.A. Lewis, J.S. Moore and S.R. White, Nature Materials, 6, 581—585 (2(X)7) with permission from Macmillan Publishers Ltd. 

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