Stripping tape

The pH of intact skin ranges from about 4.8 to 6.0, while interstitial fluid exhibits a pH that is near neutral. The low pH on skin is attributed mainly to the presence of the so-called acid mantle , a natural skin barrier to the external environment [172], Wagner et al. [173] measured both in-vivo and in-vitro pH profiles across human stratum comeum (SC) using the tape stripping technique and a flat surface pH electrode (InLab 426 from Mettler Toledo). They found a steep pH increase from pH 6 to 8 in the first 100 pm after the removal of the SC. 

Chao, Y.C., Nylander-French, L.A., Determination of keratin protein in a tape-stripped skin sample from jet fuel exposed skin, Ann. Occup. Hyg., 48, 65, 2004. 

Urocanic acid (2-propanoic acid 3-[lH-imidazol-4-yl] is located superficially in the stratum comeum. Metabolism of epidermal UCA does not occur in situ due to the absence of urocanase, resulting in the accumulation of UCA in the epidermis. Upon UV exposure, naturally occurring trans-UCA converts to the d.s-isomer, in a dose dependent manner, until the photostationary state is reached, when equal quantities of trans- and m-UCA are found in the skin.15 Based on an analysis of the action spectrum for UV-induced immune suppression, and the fact that no immune suppression was observed in mice whose stratum comeum was previously removed by tape stripping, De Fabo and Noonan suggested that urocanic acid was the photoreceptor for UV-induced immune suppression.16 Since the initial experiments many others have documented, the ability of ris-UCA to initiate immune suppression, documented its presence in the serum of UV-irradiated mice, and demonstrated that m-UCA plays a role in UV-induced skin cancer induction. (For a more complete review of the role of m-UCA in immune suppression see two excellent reviews by Norval and colleagues.1718)... 

Skin tape stripping can be used to determine the concentration of chemical in the stratum comeum at the end of a short application period (30 min) and by linear extrapolation predict the percutaneous absorption of that chemical for longer application periods. The chemical is applied to skin of animals or humans, and after a 30-minute skin contact application time, the stratum comeum is blotted and then removed by successive tape applications. The tape strippings are assayed for chemical content. There is a linear relationship between this stratum comeum reservoir content and percutaneous absorption. The major advantages of this method are (1) the elimination of urinary and fecal excretion to determine absorption and (2) the applicability to nonradiolabeled determination of percutaneous absorption, because the skin strippings contain adequate chemical concentrations for nonlabeled assay methodology. 

Skin Segmentation Studies — Tape Stripping Method... 

Drug levels within the stratum corneum can be assessed by sampling single corneocyte layers with adhesive film. The drug is then extracted from the tape-strips and quantified by a suitable analytical method. Usually, scintillation counting (for radioactive compounds) or high performance liquid... 

The tape-stripping technique has been applied in vivo, as well as in vitro. The used in vitro incubation devices are the same as described for skin permeation studies. A specialized incubation device developed by Loth and coworkers, the Saarbriicken penetration model, allows investigation of skin penetration bypassing the normally occurring nonphysiological hydration of the dermis [64],... 

Determination of the stratum corneum depth by Tape-Strip Number... 

M. B. Reddy, A. L. Stinchcomb, R. H. Guy, and A. L. Bunge. Determining dermal absorption parameters in vivo from tape strip data. Pharm. Res. 19 292-298 (2002). 

J.-C. Tsai, M. J. Cappel, N. D. Weiner, G. L. Flynn, and J. Ferry. Solvent effects on the harvesting of stratum corneum from hairless mouse skin through adhesive tape stripping in vitro. Int. J. Pharm. 68 127-133 (1991). 

H.-J. Weigmann, J. Lademann, H. Meffert, H. Schaefer, and W. Sterry. Determination of the horny layer profile by tape stripping in combination with optical spectroscopy in the visible range as a prerequisite to quantify percutaneous absorption. Skin Pharmacol. Appl. Skin. Physiol. 12 34-45 (1999). 

F. Dreher, B. S. Modjtahedi, S. P. Modjtahedi, and H. I. Maibach. Quantification of stratum corneum removal by adhesive tape stripping by total protein assay in 96-well microplates. Skin Res. Technol. 11 97-101 (2005). 

Weerheim A, Ponec M (2001) Determination of stratum corneum lipid profile by tape-stripping in combination with high-performance thin-layer chromatography. Arch Dermatol Res 293 191-199. 

A dermal absorption rate of 329 mnol/minute/cm ( 60 nmol/minute/cm ) was calculated for the shaved abdominal skin of mice (Tsumta 1975). This is equivalent to a human absorption rate of 29.7 mg/minute, assuming that a pair of hands are immersed in liquid chloroform (Tsumta 1975). However, this calculation was based on the assumptions that the rate of chloroform penetration is uniform for all kinds of skin and that the total surface area of a pair of human hands is 800 cm the former assumption is especially dubious. Islam et al. (1995) investigated the fate of topically applied chloroform in male hairless rats. For exposures under 4 minutes, chloroform-laden water was applied to shaved back skin for exposures of 4-30 minutes, rats were submerged in baths containing chloroform-laden water. Selected skin areas were tape-stripped a various number of times after various delay periods. It appeared that there was an incremental build-up of chloroform in the skin over the first four minutes. When compared to uptake measured by bath concentration differences, approximately 88% of lost chloroform was not accounted for in the stratum comeum and was assumed to be systemically absorbed. 

Islam et al. (1995) investigated the fate of topically applied chloroform in male hairless rats. For exposures under 4 minutes, chloroform-laden water was applied to shaved back skin for exposures of 4-30 minutes, rats were submerged in baths containing chloroform-laden water. Selected skin areas were tape-stripped a... 

Tape the switch to the top of the tube. Wrap an additional tape strip between the brass contacts of the switch. Leave a small tab so that you can tear it off quickly. This will function as a safety. 

The traditional methods for evaluation of the delivery and metabolism of exogenous materials in skin involve the use of diffusion cells and/or tape stripping followed by HPLC and mass spectrometry. These methods involve modification of the skin, provide no spatial information, and may alter skin transport properties. In this section, both the permeation and metabolism of a-TAc are monitored inside skin with confocal Raman microscopy. 

Jacobi, U., et al. 2005. Estimation of the relative stratum corneum amount removed by tape stripping. Skin Res Technol 11 91. 

Loffler, H., F. Dreher, and H.I. Maibach. 2004. Stratum corneum adhesive tape stripping Influence of anatomical site, application pressure, duration and removal. Br J Dermatol 151 746. 

For emulsion tests, polyamide-coated terephthalate plastic plates are attached powder-side down by double-faced transparent tape strips to the undersurface of the lid of 9 x 1 cm Pyrex Petri dishes. The plates, 2x3 cm, are cut from standard 20 x 20 cm polyamide-terephthalate plates used for thin-layer chromatography. They are Polygram - Polyamide-6 UV254, procured from Macherey-Nagel and Co. through Brinkmann Instruments, Inc., Westbury, N.Y. As indicated, they contain a fluorophore (zinc silicate) activated by short-wave UV, but not active in the 360-nm range used herein. 

The intercellular pathway is now accepted as the major pathway for absorption. Recall that the rate of penetration is often correlated with the partition coefficient. In fact this is a very tortuous pathway, and the h (skin thickness) in Fick s first law of diffusion is really 10 x the measured distance. By placing a solvent (e.g., ether, acetone) on the surface or tape stripping the surface, the stratum comeum (SC) is removed, and absorption can be significantly increased by removing this outer barrier. This may not be the case for very lipophilic chemical. This is because the viable epidermis and dermis are regarded as aqueous layers compared to the SC. Note that the more lipophilic the drug, the more likely it will form a depot in the SC and be slowly absorbed over time and thus have a prolonged half-life. 

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