Dávid Garbaisz

Attenuation of Skeletal Muscle and Renal Injury to the Lower Limb following Ischemia-Reperfusion Using mPTP Inhibitor NIM-811

Introduction Operation on the infrarenal aorta and large arteries of the lower extremities may cause rhabdomyolysis of the skeletal muscle, which in turn may induce remote kidney injury. NIM-811 (N-metyl-4-isoleucine-cyclosporine) is a mitochondria specific drug, which can prevent ischemic-reperfusion (IR) injury, by inhibiting mitochondrial permeability transition pores (mPTP). Objectives Our aim was to reduce damages in the skeletal muscle and the kidney after IR of the lower limb with NIM-811. Materials and methods Wistar rats underwent 180 minutes of bilateral lower limb ischemia and 240 minutes of reperfusion. Four animal groups were formed called Sham (receiving vehicle and sham surgery), NIM-Sham (receiving NIM-811 and sham surgery), IR (receiving vehicle and surgery), and NIM-IR (receiving NIM-811 and surgery). Serum, urine and histological samples were taken at the end of reperfusion. NADH-tetrazolium staining, muscle Wet/Dry (W/D) ratio calculations, laser Doppler-flowmetry (LDF) and mean arterial pressure (MAP) monitoring were performed. Renal peroxynitrite concentration, serum TNF-α and IL-6 levels were measured. Results Less significant histopathological changes were observable in the NIM-IR group as compared with the IR group. Serum K+ and necroenzyme levels were significantly lower in the NIM-IR group than in the IR group (LDH: p<0.001; CK: p<0.001; K+: p = 0.017). Muscle mitochondrial viability proved to be significantly higher (p = 0.001) and renal function parameters were significantly better (creatinine: p = 0.016; FENa: p<0.001) in the NIM-IR group in comparison to the IR group. Serum TNF-α and IL-6 levels were significantly lower (TNF-α: p = 0.003, IL-6: p = 0.040) as well as W/D ratio and peroxynitrite concentration were significantly lower (p = 0.014; p<0.001) in the NIM-IR group than in the IR group. Conclusion NIM-811 could have the potential of reducing rhabdomyolysis and impairment of the kidney after lower limb IR injury.

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.

Levosimendan: a cardiovascular drug to prevent liver ischemia-reperfusion injury?

Introduction Temporary occlusion of the hepatoduodenal ligament leads to an ischemic-reperfusion (IR) injury in the liver. Levosimendan is a new positive inotropic drug, which induces preconditioning-like adaptive mechanisms due to opening of mitochondrial KATP channels. The aim of this study was to examine possible protective effects of levosimendan in a rat model of hepatic IR injury. Material and Methods Levosimendan was administered to male Wistar rats 1 hour (early pretreatment) or 24 hours (late pretreatment) before induction of 60-minute segmental liver ischemia. Microcirculation of the liver was monitored by laser Doppler flowmeter. After 24 hours of reperfusion, liver and blood samples were taken for histology, immuno- and enzyme-histochemistry (TUNEL; PARP; NADH-TR) as well as for laboratory tests. Furthermore, liver antioxidant status was assessed and HSP72 expression was measured. Results In both groups pretreated with levosimendan, significantly better hepatic microcirculation was observed compared to respective IR control groups. Similarly, histological damage was also reduced after levosimendan administration. This observation was supported by significantly lower activities of serum ALT (pearly = 0.02; plate = 0.005), AST (pearly = 0.02; plate = 0.004) and less DNA damage by TUNEL test (pearly = 0.05; plate = 0.034) and PAR positivity (pearly = 0.02; plate = 0.04). Levosimendan pretreatment resulted in significant improvement of liver redox homeostasis. Further, significantly better mitochondrial function was detected in animals receiving late pretreatment. Finally, HSP72 expression was increased by IR injury, but it was not affected by levosimendan pretreatment. Conclusion Levosimendan pretreatment can be hepatoprotective and it could be useful before extensive liver resection.

Impaired Intestinal Mucosal Barrier upon Ischemia-Reperfusion: “Patching Holes in the Shield with a Simple Surgical Method”

Mesenteric ischemia-reperfusion (IR) is associated with impairment of the gut barrier function and the initiation of a proinflammatory cascade with life-threatening results. Therefore methods directed to ameliorate IR injury are of great importance. We aimed at describing the effects of postconditioning (PC) on the alterations of the intestinal mucosal function and the inflammatory response upon mesenteric IR. Methods. Male Wistar rats were gavaged with green fluorescent protein-expressing E. coli suspensions. Animals were randomized into three groups (n = 15), sham-operated, IR-, and PC-groups, and underwent 60 minutes of superior mesenteric artery occlusion, followed by 6 hours of reperfusion. Postconditioning was performed at the onset of reperfusion. Blood and tissue samples were taken at the end of reperfusion, for histological, bacteriological, and plasma examinations. Results. The PC-group presented a more favorable claudin-2, claudin-3, claudin-4, and zonula occludens-1 membrane expression profile, and significantly lower rates of bacterial translocation to distant organs and plasma D-lactate levels compared to the IR-group. Histopathological lesions, plasma I-FABP, IL-6, and TNF-α levels were significantly lower in the PC-group compared to the IR-group. Conclusion. The use of postconditioning improved the integrity of the intestinal mucosal barrier upon mesenteric IR, and thus reduced the incidence of bacterial translocation and development of a systemic inflammatory response.

Therapeutic option for managing lung injury induced by infrarenal aortic cross-clamping

BACKGROUND Operations on the infrarenal aorta can cause ischemic-reperfusion (IR) injury in local tissues, which could result in remote organ (e.g., lung) damage. Treatment of such injuries remains an unresolved problem. OBJECTIVES Our aim was to reduce remote lung damage after lower limb IR by means of postconditioning. MATERIALS AND METHODS Male Wistar rats were divided into three groups: Sham-operated, IR, and Postconditioned (PostC). In the latter two groups rats underwent 180 min of exclusion of the infrarenal aorta. The reperfusion time was 4 h. Serum-free radical levels, tumor necrosis factor-α and interleukin-6 concentrations, histologic changes in the lung, wet/dry-ratio, myeloperoxidase activity, heat shock protein 72 level and blood gas changes were investigated. RESULTS Postconditioning reduced histological damage in the lung (P < 0.05). Free radical levels and tumor necrosis factor-α concentrations were significantly lower in the PostC group than in the IR group (P < 0.05 and P < 0.01, respectively). Interleukin-6 concentrations did not significantly differ in the PostC group. Compared with the IR group, lung myeloperoxidase activity was lower in the PostC group. Decreased pulmonary heat shock protein 72 level was observed in the PostC group compared with the IR group and the wet/dry-ratio was also significantly lower in the PostC group (P < 0.05). A noticeably higher arterial pO2 level was manifest in the PostC group after 2 and 4 h of reperfusion (P < 0.05). CONCLUSIONS Postconditioning reduced lung damage under experimental conditions, in the early period of reperfusion after lower limb IR injury.

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.

Collateral circulation of the rat lower limb and its significance in ischemia–reperfusion studies

AbstractPurpose Rats are the most commonly used animal model for studies of acute lower limb ischemia–reperfusion. The ischemia induced by arterial clamping may cause milder damage than the application of a tourniquet if the presence of a possible collateral system is considered.MethodsMale Wistar rats were randomized into three groups: in group A, the muscle weight affected by ischemia was measured; in group B, the severity of muscle damage caused by the application of a tourniquet and by infrarenal aortic occlusion was examined. Blood and muscle samples were taken from group B to assess the serum necroenzyme, potassium and TNF-α levels, as well as the muscle fiber viability and for histological examinations. In group C, the identification of the lower limb collateral system was performed using corrosion casting.ResultsTourniquet application affected the lower muscle mass and resulted in significantly more severe injury compared to infrarenal aortic occlusion. This difference was reflected in the serum necroenzyme, potassium and TNF-α levels. The histological examination and viability assay confirmed these findings. The corrosion casts showed several anastomoses capable of supplying the lower limb.ConclusionTourniquet application proved to be capable of inducing absolute lower limb ischemia, in contrast to infrarenal aortic ligation, where a rich collateral system is considered to help mitigate the injury.

Postconditioning attenuates remote organ injury after lower limb arterial occlusion

Abstract Introduction External aortic compression due to acute gastric dilation is a rare etiology of the lower limb ischemia. This phenomenon leads the author to design experimental study for reperfusion syndrome. The lower limb ischemia-reperfusion (IR) injury consists of local and systemic components called the reperfusion syndrome. It can progrediate into a multi-organ failure which defines postoperative survival. A postconditioning is a surgical technique, which has a potential to reduce IR injury, therefore to prohibit the development of reperfusion syndrome. Aim XXXto examine on an experimental model, whether postonditioning is a practicable technique in infarenal aortic surgeries. Materials and Methods Male Wistar rats underwent 180 minutes of infrarenal aortic occlusion with 4, 24 and 72 hours of reperfusion. Postconditioning (10 sec. reocclusion / 10 sec. perfusion in 6 cycles) was applied in one group of each reperfusion time. Blood, urine, and histological (muscle, lung, kidney and liver) samp...

Arteria iliaca aneurysma nyitott és endovascularis kezelése

Absztrakt: Bevezetes es celkitűzes: Az arteria iliaca aneurysmak az osszes aneurysmak 2%-at teszik ki. Optimalis kezelesuk nem egyertelmű, sebeszi kezelesuk eredmenyeiről alig all rendelkezesre hazai adat. Celkitűzesunk volt az arteria iliaca aneurysma miatt operalt betegek mortalitasanak es perioperativ morbiditasanak elemzese, valamint az elektiv nyitott műteten es stentgraft-implantacion (EVIAR) atesett betegcsoportok eredmenyeinek osszehasonlitasa. Modszer: Egy intezmenyben 2005. januar 1. es 2014. december 31. kozott arteria iliaca aneurysma miatt műteten atesett betegek retrospektiv vizsgalata. Eredmenyek: Tiz ev alatt 62 betegnel vegeztunk elektiv műtetet arteria iliaca aneurysma miatt (54 ferfi [87,1%]). A betegek atlageletkora 68,9 ev (19–89 ev) volt. Tiz esetben vegeztunk akut műtetet aneurysma ruptura miatt (13,9%), ezek kozul 3 beteg halt meg a perioperativ időszakban (30%). Az anatomiai lokalizaciot tekintve tobbsegeben az arteria iliaca communison (80,6%) alakult ki ertagulat. Elektiv beavat...

Homograftok szerepe az alsó végtagi érrekonstrukciókban

INTRODUCTION Vascular homografts are used for limb salvage in cases of graft infection after previous reconstructive vascular surgery or inadequate autologous veins. During multi-organ donation the thoracic aorta segment, aortic bifurcation, iliac arteries, femoral arteries, popliteal arteries, femoral veins and greater saphenous veins can be harvested. Our aim was to optimize the use of homografts by analyzing the results of previous procedures. METHODS The patient information was processed retrospectively, using the clinical computer system. 162 procedures were performed on 144 patients between 2007 and 2014. The short- and long-term patency, hemorrhagic complication rate, amputation rate and mortality was examined in our study. The location, graft type and length of cryopreservation were taken into consideration. Aortoiliac and femoropopliteal reconstructions with arterial and venous homografts were examined. RESULTS The mean age of the patients was 63.6 ± 10.7 years, the mean follow-up period was 36 ± 28 months. The primary patency rates at the postoperative 1, 3 and 6 months were 83.7%, 75.0% and 63.4%. In this study the arterial and deep venous homografts had better primary patency rates compared to the superficial venous homografts: at the postoperative 1, 3, 6 months the arterial homograft results were 85.6%, 78.6% and 74.3%, the greater saphenous vein homograft results were 81.4%, 70.4% and 47.7% in the same intervals. CONCLUSION The reconstructive surgical procedures in septic area mean serious challenge for the vascular surgeons. The AB0 compatibility of the graft and the recipient did not result better long-term outcomes compared to the non-compatible grafts. According to our data the ideal choice of homogenous graft is an arterial homograft which was not cryopreserved longer than 6 months.