Lucí Rezende Bevilacqua

Morphological changes in distant muscle fibers following thermal injury in Wistar rats

PURPOSE Thermal injury causes catabolic processes as the body attempts to repair the damaged area. This study evaluated the effects of a scald injury on the morphology of muscle fibers belonging to a muscle distant from the lesion. METHODS Thirty Wistar rats were divided into control (C) and scalded (S) groups. Group S was scalded over 45% of the body surface, standardized by body weight. Rats in both groups were euthanized at four, seven and 14 days following the injury. The middle portions of the medial gastrocnemius muscles were sectioned, stained with hematoxylin and eosin and Picrosirius, and submitted to histological analysis. RESULTS Control group sections exhibited equidistantly distributed polygonal muscle fibers with peripheral nuclei, characteristic of normal muscle. The injured group sections did not consistently show these characteristics; many fibers in these sections exhibited a rounded contour, variable stain intensities, and greater interfiber distances. A substantially increased amount of connective tissue was also observed on the injured group sections. CONCLUSION This experimental model found a morphological change in muscle distant from the site of thermal injury covering 45% of the body surface.

The influence of nutritional status on skin anergy in experimental cancer.

Malignant tumours as well as severe malnutrition can interfere with carcass weight, serum albumin and delayed hypersensitivity tests. In order to identify the separate effects of these two phenomena, Wistar rats were submitted to various nutritional manipulations prior to Walker-256 carcinosarcoma inoculation (TU). Six groups of well-nourished rats with positive response to the Keyhole Limpet Haemocyanin (KLH) test were studied. Three TU-bearing groups were established, [1] protein-deprived before and after TU (group DDT), [2] protein deprived before TU and later brought back to normal chow (group DNT), and [3] those receiving a complete diet throughout the experiment (group NNT). Identical control groups without TU, sham-injected, were called DDC, DNC and NNC. Tumour size and body weight were measured daily. KLH tests were done sequentially and serum albumin was determined at sacrifice. Results indicated that cancer produced marked changes in immune response. Malnutrition was responsible for anergy and weight loss, and further aberrations tended to occur when both conditions were present. Feeding was able to restore body weight and KLH response in tumour-bearing as well as in control rats, but subsequent deterioration occurred in cancer bearing rats after the first week of tumour development. It is concluded that cancer potentiates the effects of malnutrition, on body weight and immune response, but temporary recovery could be demonstrated after adequate refeeding.