Muscle Fiber Viability, a Novel Method for the Fast Detection of Ischemic Muscle Injury in Rats

Acute lower extremity ischemia is a limb- and life-threatening clinical problem. Rapid detection of the degree of injury is crucial, however at present there are no exact diagnostic tests available to achieve this purpose. Our goal was to examine a novel technique - which has the potential to accurately assess the degree of ischemic muscle injury within a short period of time - in a clinically relevant rodent model. Male Wistar rats were exposed to 4, 6, 8 and 9 hours of bilateral lower limb ischemia induced by the occlusion of the infrarenal aorta. Additional animals underwent 8 and 9 hours of ischemia followed by 2 hours of reperfusion to examine the effects of revascularization. Muscle samples were collected from the left anterior tibial muscle for viability assessment. The degree of muscle damage (muscle fiber viability) was assessed by morphometric evaluation of NADH-tetrazolium reductase reaction on frozen sections. Right hind limbs were perfusion-fixed with paraformaldehyde and glutaraldehyde for light and electron microscopic examinations. Muscle fiber viability decreased progressively over the time of ischemia, with significant differences found between the consecutive times. High correlation was detected between the length of ischemia and the values of muscle fiber viability. After reperfusion, viability showed significant reduction in the 8-hour-ischemia and 2-hour-reperfusion group compared to the 8-hour-ischemia-only group, and decreased further after 9 hours of ischemia and 2 hours of reperfusion. Light- and electron microscopic findings correlated strongly with the values of muscle fiber viability: lesser viability values represented higher degree of ultrastructural injury while similar viability results corresponded to similar morphological injury. Muscle fiber viability was capable of accurately determining the degree of muscle injury in our rat model. Our method might therefore be useful in clinical settings in the diagnostics of acute ischemic muscle injury

SUBBASE: An Authentication Scheme for Wireless Sensor Networks Based on User Biometrics

To keep a network secure, a user authentication scheme that allows only authenticated users to access network services is required. However, the limited resources of sensor nodes make providing authentication a challenging task. We therefore propose a new method of security for a wireless sensor network (WSN). Our technique, Secure User Biometric Based Authentication Scheme (SUBBASe), is based on the user biometrics for WSNs. It achieves a higher security level as well as improved network performance. This solution consists of easy operations and light computations. Herein, the proposed technique is evaluated and compared with previous existing techniques. This scheme increases the performance of the network by reducing network traffic, defending against DOS attacks, and increasing the battery life of a node. Consequently, the functionality and performance of the entire network is improved

Postconditioning Protects Skeletal Muscle Against a Long-Lasting Vascular Occlusion

ABSTRACT Purpose/Aim of the Study: Long-lasting lower limb arterial occlusion is a condition with high incidence and complication rates. With the absence of appropriate treatment to cure advanced complications, mortality rates are high. Postconditioning (PC) might be capable of limiting the degree of ischemic-reperfusion (IR) injuries, thus reducing complications and mortality rates. The aim of this study was to evaluate the impact of postconditioning during the first postoperative day on skeletal muscle after a long-lasting arterial occlusion. Materials and Methods: Male Wistar rats (n = 72) underwent 8 hr of infrarenal aortic occlusion followed by 2, 6, 12, or 24 hr of reperfusion. In one group of each reperfusion period, postconditioning was applied. Muscle samples were collected for histological examinations. Furthermore, muscle fiber viability and muscle wet-to-dry ratio were assessed. Blood samples were taken for creatine-kinase measurements. Results: Postconditioning strongly reduced morphological injury compared to the corresponding ischemic-reperfusion group (p < .001). Serum creatine-kinase levels showed a peak at 6 hr post-ischemia (IR: 6702.2 +/- 797.5; PC: 5523.3 +/- 769.3 IU/l) and decreased to normal level by the end of the experiment (Sham: 171.5 +/- 71.6; IR: 186.2 +/- 82.7; PC: 174.2 +/- 72.4 IU/l). Creatine-kinase levels were significantly reduced by postconditioning (p2hr = .028; p6hr = .06; p12hr = .042). A marked decrease in viability was observed in the ischemic-reperfusion groups (2 hr: 11.0 +/- 4.1; 6 hr: 10.3 +/- 3.6; 12 hr: 9.4 +/- 3.3; 24 hr: 8.6 +/- 2.8%), whereas with postconditioning, viability was preserved (2 hr: 26.4 +/- 5.5; 6 hr: 24.6 +/- 4.5; 12 hr: 24.5 +/- 6.8; 24 hr: 26.2 +/- 6.1%; p < .001); moreover, a significant decrease in the wet-to-dry ratio was achieved (p < .001). Conclusion: Postconditioning was able to reduce local complications after a long-lasting lower limb vascular occlusion