Morphological parameters for assessment of burn severity in an acute burn injury rat model

Abstract

Determination of burn severity (i.e. burn depth) is important for effective medical management and treatment. Using a recently described acute burn model, we studied various morphological parameters to detect burn severity. Anaesthetized Sprague-Dawley rats received burns of various severity (0- to 14-s contact time) followed by standard resuscitation using intravenous fluids. Biopsies were taken from each site after 5 h, tissues fixed in 10% neutral-buffered formalin, processed and stained with haematoxylin and eosin. Superficial burn changes in the epidermis included early keratinocyte swelling progressing to epidermal thinning and nuclear elongation in deeper burns. Subepidermal vesicle formation generally decreased with deeper burns and typically contained grey foamy fluid. Dermal burns were typified by hyalinized collagen and a lack of detectable individual collagen fibres on a background of grey to pale eosinophilic seroproteinaceous fluid. Intact vascular structures were identified principally deep to the burn area in the collagen. Follicle cell injury was identified by cytoplasmic clearing/swelling and nuclear pyknosis, and these follicular changes were often the deepest evidence of burn injury seen for each time point. Histological scores (epidermal changes) or dermal parameter depths (dermal changes) were regressed on burn contact time. Collagen alteration (r(2) = 0.91) correlated best to burn severity followed by vascular patency (r(2) = 0.82), epidermal changes (r(2) = 0.76), subepidermal vesicle formation (r(2) = 0.74) and follicular cell injury was useful in all but deep burns. This study confirms key morphological parameters can be an important tool for the detection of burn severity in this acute burn model.

Laserterapia e microcorrente na cicatrização de queimadura em ratos: terapias associadas ou isoladas?

“…On the tenth day after the burn wound was inflicted, the appearance of the skin lesion in the LG, MG, and MLG pointed to loss of epidermis and hypodermis, representing a second-degree burn 2 , with moderate acute inflammatory reaction but with a clean and uninfected wound. There was no significant difference among the groups in relation to epithelial regeneration (p=0.0568), and inflammatory process (p=0.9640).…”

“…The therapies were performed in the afternoon (2 to 5 pm). For the four groups, the procedures were performed in the following sequence: (a) administering of dissociative anesthetic Zoletil® with dosage of 50 mg/kg intramuscularly in the quadriceps muscle; (b) trichotomy on the animal's back; (c) induction of a second-degree burn wound 2 with a 6x3 cm aluminum plate pressured against the animal's back 4 cm away from the skull base during 10 seconds; the plate was previously warmed in becker with water at 100°C for a period of 10 minutes, as used by Meyerholtz et al 2 and Meireles et al 16 ( Figure 1). The proposed treatments were initiated immediately after the lesions, and performed daily during 10 days.…”

“…These resources accelerate the healing process, acting upon the sequence of physiological and biochemical events of this process through inflammation, collagen synthesis, formation of granulation tissue, and re-epithelization 1,2 . Through the analysis of cellular structures that are activated and/or inhibited by these resources, studies 2,4,5 performed on laboratory animals have contributed to the elucidation of which physiotherapy resources might promote a regenerative process of quality. The therapeutic effects have been attributed to the interaction between external energetic stimuli and the biological tissue (biostimulation), promoting an increase in cellular activities during the healing process.…”

“…In physiotherapy, several resources are being used to accelerate and improve the quality of the regenerative process, such as lasers, microcurrents, ultrasounds, and ultraviolet radiation [1][2][3] . These resources accelerate the healing process, acting upon the sequence of physiological and biochemical events of this process through inflammation, collagen synthesis, formation of granulation tissue, and re-epithelization 1,2 .…”

“…1 Physical therapist; MSc, professor of Physical therapy at Universidade Federal do Rio Grande do Norte (UFRN) -Santa Cruz (RN), Brazil. 2 Physical therapist graduated at UNP -Natal (RN), Brazil. 3 MSc in Physical therapy, Universidade Metodista de Piracicapa (UNIMEP) -Piracicaba (SP), Brazil.…”