The Role of Extracellular Superoxide Dismutase (EC-SOD) in Skeletal Muscle Ischemia-reperfusion Injury / 대한정형외과학회잡지

PURPOSE: This study investigated the role of extracellular superoxide dismutase (EC-SOD), which is a major extracellular antioxidant enzyme in skeletal muscle ischemia and reperfusion (I/R) injury. MATERIALS AND METHODS: The pedicled cremaster muscle flaps from homozygous EC-SOD knockout (EC-SOD-/-), heterozygous CuZn-SOD knockout (CuZn-SOD+/-) and wild-type (WT) mice were subjected to 4.5 hour ischemia followed by 90 min reperfusion. The pedicled cremaster muscle flaps were examined by functional analysis during the reperfusion. The mRNA and protein expressions of each SOD after I/R were evaluated using quantitative real-time PCR and western blot. RESULTS: The results showed that the EC-SOD-/- mice had a more profound I/R injury than the CuZn- SOD+/- or WT mice. In particular, there was a delayed and incomplete recovery of the arterial diameter and blood flow during reperfusion and as well as there being more severe inflammation. After 90 min reperfusion, the EC-SOD mRNA levels increased more in the CuZn-SOD+/- mice than in the WT mice. However, the CuZn-SOD and Mn-SOD mRNA levels decreased similarly in all 3 groups. The CuZn-SOD protein levels decreased in all groups. The EC-SOD protein levels decreased in the CuZn-SOD+/- and WT mice, but the Mn-SOD protein levels were unchanged or slightly increased in all groups. The histological results showed diffuse edema and inflammatory cell infiltration around the muscle fibers and these changes were more severe in the EC-SOD-/- mice. CONCLUSION: EC-SOD plays an important role in protecting the skeletal muscle from I/R injury caused by the excessive generation of reactive oxygen species.

Intrathoracic Migration of K-wire after Fixation of Proximal Huemrus Fracture: Case Report

We report an unusual case of Kirschner wire migration from the proximal humerus into the thoracic cavity and diaphragm which induced pneumothorax and hemoperitoneum. An 81-year-old woman admitted to the emergency room due to sudden onset of dyspnea. X-rays showed pneumothorax and old proximal humerus fracture fixed with rush pins and K-wires. One of K-wires was seen on the diaphragm level at posterior gutter of chest wall. Through the abdomen, K-wire was removed from the diaphragm and a chest tube was inserted. The potential for K-wires to migrate must be recognized, and frequent postoperative radiographic studies have to be performed for the early detection of loosening and migration. It appears that if K-wires are used for fixation of proximal humerus, the lateral ends must be bent to prevent medial migration, and when the desired therapeutic goals have been achieved, these pins have to be susbsequently removed as soon as possible.