Wound dressings for a proteolytic-rich environment

Wound dressings have experienced continuous and significant changes over the years based on the knowledge of the biochemical events associated with chronic wounds. The development goes from natural materials used to just cover and conceal the wound to interactive materials that can facilitate the healing process, addressing specific issues in non-healing wounds. These new types of dressings often relate with the proteolytic wound environment and the bacteria load to enhance the healing. Recently, the wound dressing research is focusing on the replacement of synthetic polymers by natural protein materials to delivery bioactive agents to the wounds. This article provides an overview on the novel protein-based wound dressings such as silk fibroin keratin and elastin. The improved properties of these dressings, like the release of antibiotics and growth factors, are discussed. The different types of wounds and the effective parameters of healing process will be reviewed

Effective enzymatic debridement of burn wounds depends on the denaturation status of collagen

The treatment of burn wounds by enzymatic debridement using bromelain has shown promising results in our burn center. However, inadequate debridement occurred in a few cases in which the etiology of the burn was attributed to relatively low temperature burns. We hypothesized that bromelain is ineffective in burns in which collagen denaturation, which occurs approximately at 65°C, has not taken place. Our objective was to assess whether there is a relationship between the denaturation of collagen and the ability of bromelain to debride acute scald burn wounds of different temperatures. Ex vivo human skin from four different donors was cut into 1x1 cm samples, and scald burns were produced by immersion in water at temperatures of 40°C, 50°C, 60°C, 70°C, and 100°C for 20 minutes. Denaturation of collagen was assessed with histology, using hematoxylin and eosin (H&E) staining and a fluorescently labeled collagen hybridizing peptide (CHP), and with second harmonic generation (SHG) microscopy. Burned samples and one control sample (room temperature) were weighed before and after application of enzymatic debridement to assess the efficacy of enzymatic debridement. After enzymatic debridement, a weight reduction of 80% was seen in the samples heated to 70°C and 100°C, whereas the other samples showed a reduction of 20%. Unfolding of collagen, loss of basket‐weave arrangement, and necrosis was seen in samples heated to 60°C or higher. Evident CHP fluorescence, indicative of collagen denaturation, was seen in samples of 60°C, 70°C and 100°C. SHG intensity, signifying intact collagen, was significantly lower in the 70°C and 100°C group (P <.05) compared to the lower temperatures. In conclusion, denaturation of collagen in skin samples occurred between 60°C and 70°C and strongly correlated with the efficacy of enzymatic debridement. Therefore, enzymatic debridement with the use of bromelain is ineffective in scald burns lower than 60°C

Cost study of dermal substitutes and topical negative pressure in the surgical treatment of burns

Background: A recently performed randomised controlled trial investigated the clinical effectiveness of dermal substitutes (DS) and split skin grafts (SSG) in combination with topical negative pressure (TNP) in the surgical treatment of burn wounds. In the current study, medical and non-medical costs were investigated, to comprehensively assess the benefits of this new treatment. Methods: The primary outcome was mean total costs of the four treatment strategies: SSG with or without DS, and with or without TNP. Costs were studied from a societal perspective. Findings were evaluated in light of the clinical effects on scar elasticity. Results: Eighty-six patients were included. Twelve months post-operatively, highest elasticity was measured in scars treated with DS and TNP (p = 0.027). The initial cost price of treatment with DS and TNP was (sic)2912 compared to treatment with SSG alone (sic)1703 (p < 0.001). However, mean total costs per patient did not differ significantly between groups (range (sic)29 097 -(sic)43 774). Discussion: Costs of the interventional treatment contributed maximal 7% to the total costs and total costs varied widely within and between groups, but were not significantly different. Therefore, in the selection of the most optimal type of surgical intervention, cost considerations should not play an important role. (C) 2013 Elsevier Ltd and ISBI. All rights reserved

Morphometry of Dermal Collagen Orientation by Fourier Analysis Is Superior to Multi-Observer Assessment

In human dermis, collagen bundle architecture appears randomly organized, whereas in pathological conditions, such as scar tissue and connective tissue disorders, collagen bundle architecture is arranged in a more parallel fashion. Histological examination by one or two observers using polarized light is the most common method to determine collagen orientation. The hypothesis on which this study is based is that an objective image analysis technique, Fourier analysis, would improve the reliability (are the measurements reproducible?) and the accuracy (does the method measure what it is supposed to measure?) of collagen orientation assessment, compared with observer ratings. Fourier analysis was applied to 271 images of scar tissue and normal skin that were acquired by confocal laser-scanning microscopy. Observers rated the same areas using polarized light as well as the confocal microscopy images. Computer images consisting of different types of ellipses were generated with a fixed orientation. Observers and Fourier analysis evaluated the images to evaluate accuracy. The inter-observer reliability was acceptable when at least three observers rated polarized light images (r > 0.69), whereas two observers were sufficient for rating confocal microscopy images (r > 0.71). Fourier analysis correlated better with observer ratings of confocal microscopy images (r = 0.69) than with polarized light microscopy images (r = 0.42). Fourier analysis was more accurate than four observers for the evaluation of the 'true' orientation for almost all types of computer-generated images. For the first time it is shown that Fourier image analysis is suitable for the morphometry of dermal collagen orientation and leads to a superior measurement of collagen orientation compared with subjective histological evaluation by several experts. If an evaluation is performed by conventional light microscopy, at least three observers are required to attain an acceptable inter-observer reliability