A novel human ex-vivo burn model and the local cooling effect of a bacterial nanocellulose-based wound dressing.

BACKGROUND: Burn wound progression is a significant problem as burns initially thought to be superficial can actually become full thickness over time. Cooling is an efficient method to reduce burn wound conversion. However, if the cooling agent is below room temperature, depending on the wound size the patient is at risk of hypothermia. Additionally, tissue perfusion is reduced leading to an aggravation of burn wound progression. We investigated if wound dressings based on non-pre-cooled bacterial nanocellulose (BNC) with a high water content cool a burn just by evaporation and reduce the intradermal damages in the skin. MATERIAL AND METHODS: In a human ex-vivo model, skin explants underwent contact burns using a 100 °C hot steel block. The burned areas were divided into two groups of which one was cooled with a BNC-based wound dressing. Intradermal temperature probes measured temperature in cooled and uncooled burn sites over 24 h. For histological assessments of the burned areas biopsies were taken at different time points. High mobility group box-1 (HMBG1) staining served as marker for cell vitality and necrosis in the different skin layers. RESULTS: Intradermal temperature measurement showed that application of the BNC-based wound dressing reduced temperature significantly in burned skin. This cooling effect resulted in a maximum temperature difference of 6.4 ± 1.9 °C and a significant mean reduction of the area under the curve in the first hour after burn of 62% (p < 0.0001). The histological results showed less necrosis and less dermal-epidermal separation in the cooled areas. The HMGB1 staining revealed more vital cells in the cooled group than in the uncooled group. CONCLUSION: Based on our results, BNC-based wound dressings cool a burn. Intradermal temperature as well as thermal damage of the tissue was reduced. The tested BNC-based wound dressing can be used without pre-cooling to cool a burn as well as to reduce the burn BNC-based wound progression through its evaporation cooling effect.

Granular parakeratosis--a clinical-pathological correlation of 10 cases.

BACKGROUND: Granular parakeratosis describes chronic skin lesions within the intertriginous areas that demonstrate microscopically parakeratosis together with retention of keratohyalin granules within a thickened stratum corneum. Granular parakeratosis is rarely diagnosed, since it is still relatively unknown within the differential diagnoses of intertriginous eruptions, and a skin biopsy is required for diagnosis. In order to gain insight into the clinical-histopathologic correlation, we present 10 cases of granular parakeratosis. METHODS: The files of the DermatoHistologisches Labor Dr. H. Laaff, Freiburg, were searched for the diagnosis of granular parakeratosis. Identified cases were evaluated for clinical information and histopathologic characteristics. RESULT: From 2004 to 2007 10 cases (7 women, 3 men) of granular parakeratosis were found corresponding to a frequency of 0.004%. The average age was 62 (33-82). In women lesions occurred in submammary region (4), axillae (2) and popliteal fossa; in men, groin (2) and genital region. Clinically two different patterns are recognized--lichen planus-like red-brown slightly hyperkeratotic or scaly papules, and larger plaques which are either bright red shiny or grey-brown with lichenification. Histologically the typical granular parakeratosis was seen in a prominently thickened stratum corneum. It remains unclear whether granular parakeratosis is a disease entity or whether it reflects a reaction pattern to unknown stimuli.