Ação do dimetil-sulfóxido na isquemia de retalhos randômicos de pele em ratos / The role of subcutaneous methyl-sulfoxide in a morphological study of random skin flaps in rats

Objetivo: Avaliar a ação do dimetil-sulfóxido (DMSO) na necrose distal de retalhos randômicos isquêmicos em ratos. Métodos: Foram utilizados 30 ratos machos, linhagem Wistar, peso entre 220 e 363g e idade média de 3 meses. O retalho cutâneo dorsal (8x2cm) com pedículo cranial foi descolado, reposto em seu leito e suturado com poliamida 4.0. O grupo controle-CT (n=10) não recebeu nenhuma medicação, o grupo simulado-SM (n=10) recebeu o volume de 1mL de solução salina subcutânea, dividida em dez aplicações ao longo do retalho, o grupo experimento-EX (n=10) recebeu a injeção de 1ml de DMSO 5 por cento. Após sete dias foram avaliadas as áreas de necrose distal e colhido material para o estudo histológico. Resultados: As medidas das áreas de necrose (CT=47,99, SM=58,78, EX=41,57) e as porcentagens das áreas de necrose (CT=29,98, SM=36,73, EX=23,99) mostraram-se menores no grupo Ex (p< 0,05). O estudo histológico qualitativo mostrou, no grupo Ex, maior presença de neovascularização, menor desestruturação dos anexos e do estroma conjuntivo e presença de fibroblastos em período mais precoce que nos dois outros grupos. Conclusão: O DMSO teve ação benéfica sobre os retalhos cutâneos randômicos em ratos, expressos pela menor área de necrose distal e pelo aspecto histológico de reparação tecidual mais precoce.

Tracheotomy in growing rats: histological aspects

PURPOSE: To compare morphologically three different types of tracheotomy in growing rats, applying microsurgical technique. METHODS: EPM-1 Wistar growing rats (n=57) weighing 88gm and aged 35 days were randomized in four groups, according tracheotomy incision type (longitudinal, transverse and tracheal segment excision), and sham group. Following intramuscular anesthesia with ketamine and xylazine, the trachea was exposed and incised, according to the group, and a hand-made endotracheal cannula was inserted into the organ, under sterile conditions. This cannula was removed after 7 days, and animals have been sacrificed 30 days later. Tracheas samples were submitted to histological study, stained by hematoxylin-eosin and Masson trichrome, evaluating fibrosis, inflammatory infiltrate and epidermoid metaplasia. RESULTS: There was more frequency of inflammatory infiltrate at the tracheal epithelium in the tracheal segment excision group (87 percent) compared to the longitudinal (40 percent) and transverse (36 percent) incision groups (p=0.009). Evaluating epidermoid metaplasia, tracheal segment excision and the longitudinal groups presented 33 percent and 40 percent, respectively, compared to 0 percent of the transverse group (p=0.03). Concerning to fibrosis, in a global comparison (p=0.1) among the three groups there was no difference, however, compared to the longitudinal group the transverse group showed lower level of fibrosis (p=0.04). Sham group did not present any relevant morphologic alterations and it was used as reference pattern. CONCLUSION: Taken together, our data show that tracheal segment excision promotes more epithelium aggression and transverse tracheal incision shows less morphologic alterations.