Dermal Tissues

The penetration of light into and through dermal tissues has important consequences. This penetration is demonstrated in Fig. 11.1. Skin, as the primary organ responsible for thermal regulation, is overperfused relative to its metabolic requirements (Anderson and Parrish, 1981). 

It is often demanded that the surface of polymeric biomaterials should exhibit permanent tenacious adhesion to soft connective and dermal tissues. However, conventional non-porous, polymeric materials will be encapsulated by a fibrous membrane generated de novo by surrounding fibroblasts, when subcutaneously implanted into the living body in contact with soft connective tissues. This is a typical foreign body reaction of the living system to isolate foreign materials from the host inside the body. On the other hand, it should be noted that the small gap present between a percutaneously-implanted device and the surrounding tissue provides a possible route for bacterial infection because of the lack of microscopic adhesion at the interface. 

Biopol . [Brods Industries] Dermal tissue extract for skin and hair care cosmetics. 

Because absorbed compounds are taken up by blood vessels in the papillary dermal tissue, most of the dermal tissue should be removed prior to assembhng skin in a diffusion cell. This split-thickness preparation of skin is often prepared with a dermatome because it can be used for all types of skin, and the viabihty of skin can... 

Cross, S.E., Wu, Z.-Y., and Roberts, M.S., Effect of perfusion flow rate on the dermal tissue uptake of solutes after dermal application using the isolated perfused rat hindlimb preparation, J. Pharm. Pharmacol, 1994, 46, 844-850. 

Percutaneous absorption may be measured In vivo or It may be determined In vitro using excised skin mounted In glass diffusion cells. The most frequently used approaches employ radlolabelled compounds. The validity of In vitro measurements relies on the assumption that no metabolism occurs In skin, and that absorption Into the receptor fluid of the diffusion cells approximates absorption from dermal tissue Into blood In vivo. These assumptions are generally unproven, and In vitro measurements ultimately require confirmation In vivo. These limitations notwithstanding, In vitro studies still provide substantially useful Information, and a variety of methods have been developed. The first section of this paper will focus on the general Interpretation of In vitro data and Its application to risk assessment. 

The problem of obtaining a functional and viable interface between the tissue (skin) and an implant (percutaneous device) is primarily due to the following factors. First, although initial attachment of the tissue into the interstices of the implant surface occurs, attachment cannot be maintained for a sustained time since the dermal tissue cells turn over continuously. Downgrowth of epithelium around the implant or overgrowth on the implant leads to extrusion or invagination, respectively. Second, any opening near... 

Suberin, suberic acid. Suberin (Latin suber=cork) in plants forms the lipophilic protective layer on the outer dermal tissue (cork) of trunks and branches as well as roots and other underground plant parts (see cutin). S. is also formed in plant tissues during wound healing. S. is a mixture of polyesters, the main components are a,w-dicarboxylic acids, e.g., docosane-dioic acid (see Japan wax) and tetracosanedioic acid (C24H46O4, Mr 398.63, mp. 127.1 °C), tt>- hydroxy fatty acids, fatty acids, and fatty alcohols as well as phenolic compounds. 

The skin, not the blood, is where males perceive the pheromone, however, and since our previous results indicated that the dermis contained abundant lipid, we tested minced dermal tissue in immunodiffusion tests. Initially, we tested dermal tissue of 5 intact untreated sexually attractive females, 2 long-term ovariectomized females, and 2 estradiol-treated females. Only tissue of estradiol-treated females reacted with antivitellogenin tissue of untreated females known to be sexually attractive did not react with anti-vitellogenin. However, untreated tissue did react with adjacent wells containing vitellogenin-positive control solutions. Further, the precipitation line of the reaction between untreated tissue and vitellogenin control was a line-of-identity with the antigen-antibody line and was apparent even in the absence of... 

Fig, 2. Ouchterlony radial immunodiffusion assay of sera and tissues from intact and estrogen-treated female sirtalis. Center well assay A rabbit 337 anti-vitellogenin. Center well assay B vitellogenin, 100 mg/ml. Wells 1 and 4 both assays estrogen-treated female serum. Well 2 both assays untreated female serum. Well 3 both assays dermal tissue from untreated female. Well 5 both assays dermal tissue from untreated female, treated in vitro with estradiol in PBS. Well 6 both assays dermal tissue from the same untreated female as the serum in well 2 and the tissue in well 5, treated as in well 5 but without estradion. Drawn from a plate in Garstka 0-982). 

Caprosyn retains 50% tensile strength at 5 days with a near complete absorption (intramuscular) at 56 days (Pineros-Fernandez et al., 2004), the most rapidly absorbed synthetic monofilament suture. Pineros-Fernandez et al. (2004) showed that Caprosyn had a dermal tissue drag force of 54 20 g and stiffness (the amount of suture deflection under a constant weight and suture length, that is, higher amount of suture deflection means less stiff) of 843 106 X 10 N/cm, which was significantly less than that of chromic gut. 

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