Keratinization modifiers

Distinct from hydrating agents and keratolytics that affect the stratum corneum directly are agents we categorize as keratinization modifiers. In recent publications we have reported that a-hydroxy acids as a class, and some JS-... 

The easiest way to detect a protein modification seems to be the mass measurement of all peptides generated by enzymatic digestion. The comparison with the predicted peptide masses from the sequence of the protein identifies unmodified peptides and unexplained masses would give indications to modified peptides. Unfortunately, this is not a suitable approach in practice. In many peptide mapping experiments done with the MALDI mass mapping technique, up to 30% of the measured masses remain unexplained. This is probably due to protein contaminations from human keratins, chemical modifications introduced by gel electrophoresis and the digestion procedure, and other proteins present at low levels in the piece excised from the sodium dodecyl sulfate gel. The detection of a protein modification requires a more specific analysis. 

Fey SJ, Larsen PM, Cells JE. (1983) Evidence for coordinated phosphorylation of keratins and vimentin during mitosis in transformed human amnion cells. Phosphate turnover of modified proteins. FEBS Lett 157, 165-9. 

Emollients are often added to cream formulations to modify either the characteristics of the pharmaceutical vehicle or the condition of the skin itself to promote penetration of the active ingredient to act either locally or systemically. The stratum corneum, being keratinized tissue, behaves as a semipermeable artificial membrane, and drug molecules can penetrate by passive diffusion. The rate of drug movement depends on the drug concentration in the vehicle, its aqueous solubility, and the oil/ water partition coefficient between the stratum corneum and the product s vehicle. Commonly used emollients include glycerin, mineral oil, petrolatum, isopropyl pal-mitate, and isopropyl myristate. 

FIGURE 12.1 Penetration enhancer activity, (a) Action at intercellular lipids. Some of the ways by which penetration enhancers attack and modify the well-organized intercellular lipid domain of the stratum comeum. (b) Action at desmosomes and protein structures. Such dramatic disruption by enhancers (particularly potent solvents) as they split the stratum corneum into additional squames and individual cells would be clinically unacceptable, (c) Action within comeocytes. Swelling, further keratin denaturation and vacuolation within individual horny layer cells would not be so drastic but would usually be cosmetically challenging (see Menon and Lee [69] for further details). (Reproduced from Barry, B.W., Nat. Biotechnol. 22, 165, 2004. With permission.)... 

The optimization of the extraction phase from hair with dichloromethane and methanol as modifier has recently been published by Fernandez et al. [140], In this case MAE has been used, obtaining a very rapid extraction procedure and allowing the chlorinated solvent to permeate into the structure of the hair keratin. 

The foregoing analysis makes clear that capillary electrophoresis can reveal differences in keratin proteins obtained from animals treated with ethanol compared to controls. However, it is also apparent that because of the complexity of the protein matrix, other methods must be used as well to identify the modified fraction. 

The complexity of the SC membrane hinders such definitive interpretation, but, nevertheless, alterations in endotherms can be used to screen molecules suspected of altering membrane function. Conversely, one should note that the absence of additive-induced alterations in the phase transition profile does not rale out their perturbing effect, but rather indicates that the additive does not modify the gel phase. As described earlier, a DSC thermogram of hydrated but untreated human SC yields four endotherms, the first three of which can be identified as noncooperative lipid-associated phase transitions, while the high-temperature endotheim is attributed to keratin denaturation [33,37]. 

Intercellular Volume and Penetration. The surface coats of epidermal cells occupy intercellular space and these gelatinous layers probably act as watery diffusion channels for nutrients (35). Surface coats are quite different from keratinized intercellular cement (32, 43) kera-tinization modifies desmosomes and intercellular materials to resist diffusion and premature separation in SC (32, 43, 44). 

In another paper, Pauling and Corey (1592) modified the two sheets slightly to achieve linear H bonds and give 7.0 A (antiparallel sheet) and 6.5 A (parallel sheet) as the repeat distances along the chains. The other major spacings of /3-keratin are explained as the distance between chains (4.6 A) and the distance between sheets (10 A). 

The latter method has the advantage of recycling the natural or waste product. Significant examples are cotton modified with amines [3, 4], starch utilized in xanthate form [5, 6, 7], thiol type keratine gel prepared from the wool [8, 9,10], wool simply reduced [11] or modified with amine groups [12, 13, 14] and finally polysaccharides such as cellulose [15, 16, 17], glucose [18] or polyosides [19] modified with thiol or amine groups. 

The adsorption mechanism of mercury by modified cellulose seems to be related to the number of proton present in solution. This kind of phenomenon was already observed by Miyamoto [8] who studied mercury adsorption by keratine gel and by Marchant [17] who utilized cellulose modified with thiol groups. 

Similar to other hair preparations that are formulated to modify the molecular configuration of hair, hair-removal products typically contain thioglycolate salts to dissolve the keratin protein. Because of the caustic nature of these products, care should be taken to minimize irritation to the surrounding skin. 

U.S. 4,195,077 (1980) Marsh et al. (Procter Gamble) Modified protein Protect keratinous material... 

This tumor is similar to its counterpart in salivary glands in both morphology and immunophenotype and may arise in the cervix or vulvovaginal soft tissue. It is a dual-cell population tumor growing in cribriform, tubular, and/or solid patterns. The major cell type is a basaloid polygonal cell with modified myoepithelial features, and it is positive for p63 and smooth muscle actin. The minor cell type is an epithelial cell forming tiny ductules that may be inconspicuous. These cells express keratin and CD 117. Distinction from basaloid squamous carcinoma is based on the distinct morphology of adenoid cystic carcinoma because overlap exists in immunostains p63 is diffusely expressed in basaloid squamous carcinoma, as opposed to adenoid cystic carcinoma, in which p63 is confined to basaloid cells and not epithelium of the ductules CDl 17 can be expressed at low levels in basaloid squamous carcinoma. ... 

This article concerns collagen fibers from rat tail tendon. The object is to confirm, improve or modify the proposed model by studying different collagen samples and secondly fibrous proteins such as the a keratin of human hair which exhibits similar hydration properties. 

The thiol—disulfide bonding system is important in the physical properties of a number of foods (134). Various enzymes catalyze the oxidation of thiols, the rearrangement of disulfide bonds, and the interchange of thiol-disulfide (135-141). The significance of these enzymes, some of which are found in baker s yeast (137), in the rheology of bread doughs, in other food systems, or in modifying novel proteins such as the keratins remains to be determined. 

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