bromochloroacetic-acid and Dehydration

The industrial utilisation of feather keratin as a biopolymer has proven difficult due to the lack of a viable extraction technique and the poor mechanical properties of the regenerated products. Here, pure keratin films were produced from chicken feathers using sodium sulphide as sole extraction reagent in a scheme that allows films to be formed without residual chemicals. In a comparison to other films, those produced using Na2S extraction were found to be superior to other regenerated protein films and were similar to un-oriented commercial polymers. However, there was considerable variation in tensile properties between twenty repetitions of extracting and casting films which was attributed to variations in chain entanglement caused by the drying conditions. Chemical and physical treatments including crosslinking, dehydration and addition of nano-particles were investigated as means to enhance these properties. Significant increases were achieved by soaking films in isopropyl alcohol or weak acid (13 to 50% increases) or by formaldehyde or glutaraldehyde crosslinking (24 to 40% increases). The wide range of values across the pure keratin films indicates that the best route to further strength improvement may be from optimising self-assembly via controlling drying conditions, rather than from chemical treatment.

Topics: Animals; Biopolymers; Chickens; Dehydration; Feathers; Keratins; Mechanical Phenomena; Oxidation-Reduction; Sulfides

Tinea corporis is a superficial mycotic infection resulting in substantial epidermal changes. We determined skin barrier function, epidermal differentiation, and human-beta-defensin 2 (hBD-2) protein expression in 10 patients with tinea corporis caused by Trichophyton rubrum (T. rubrum). We found disturbed skin barrier function as shown by a significant increase in transepidermal water loss (TEWL) and specific ultrastructural changes including disturbed formation of extracellular lipid bilayers, lamellar body extrusion, and deposit of clotted material at the stratum granulosum/stratum corneum interface. Epidermal proliferation in tinea increased several fold and accordingly, proliferation and inflammation-associated keratins K6, K16, and K17 were expressed. Expression of basal keratins K5 and K14 increased, whereas differentiation-associated K10 was reduced. Reduction of the cornified envelope proteins involucrin, loricrin, and the S100 protein filaggrin was also seen. Reduced filaggrin expression correlated with reduced skin hydration; protein breakdown products of filaggrin have been shown to be important for water binding. Surprisingly, we found pronounced epidermal protein expression of hBD-2, which may be related to disturbed epidermal differentiation and inflammation. hBD-2 showed a weak, although significant, antifungal activity against T. rubrum in the turbidimetric assay and the immunohistological staining was somewhat less pronounced in areas directly underneath fungal hyphae in the stratum corneum. Together, we describe profound changes in skin barrier structure and function, epidermal proliferation, and differentiation including pronounced protein expression of hBD-2 in tinea corporis.

Topics: beta-Defensins; Cell Differentiation; Cell Membrane Permeability; Cell Proliferation; Dehydration; Epidermis; Filaggrin Proteins; Gene Expression Regulation; Humans; Intermediate Filament Proteins; Keratins; Membrane Proteins; Protein Precursors; Skin Physiological Phenomena; Tinea; Trichophyton

1. We report the first measurements to be made on the effects of hydration on the mechanical properties of commercially-prepared duck down feathers. Tensile tests were performed, to failure, on isolated barbs of down feathers at 50% RH and with fully-hydrated (wet) feathers. 2. The Young's modulus (stiffness) and ultimate stress (strength) of the feathers was higher at 50% RH than when wet. Wet feathers, however, failed at greater extension than dry feathers. The implications for down feather performance and for the use of feathers as a structural material are discussed.

Topics: Animals; Dehydration; Ducks; Feathers; Humidity; Keratins; Poultry Diseases; Tensile Strength