Complete Ischemia Research Articles

Formation of eicosanoids, E2/D2 isoprostanes, and docosanoids following decapitation-induced ischemia, measured in high-energy-microwaved rat brain

Inflammatory lipid mediators derived from arachidonic acid (AA) and docosahexaenoic acid (DHA) modify the pathophysiology of brain ischemia. The goal of this work was to investigate the formation of eicosanoids and docosanoids generated from AA and DHA, respectively, during no-flow cerebral ischemia. Rats were subjected to head-focused microwave irradiation 5 min following decapitation (complete ischemia) or prior to decapitation (controls). Brain lipids were extracted and analyzed by reverse-phase liquid chromatography-tandem mass spectrometry. After complete ischemia, brain AA, DHA, and docosapentaenoic acid concentrations increased 18-, 5- and 4-fold compared with controls, respectively. Prostaglandin E(2) (PGE(2)) and PGD(2) could not be detected in control microwaved rat brain, suggesting little endogenous PGE(2)/D(2) production in the brain in the absence of experimental manipulation. Concentrations of thromboxane B(2), E(2)/D(2)-isoprostanes, 5-hydroxyeicosatetraenoic acid (5-HETE), 5-oxo-eicosatetraenoic acid, and 12-HETE were significantly elevated in ischemic brains. In addition, DHA products such as mono-, di- and trihydroxy-DHA were detected in control and ischemic brains. Monohydroxy-DHA, identified as 17-hydroxy-DHA and thought to be the immediate precursor of neuroprotectin D(1), was 6.5-fold higher in ischemic than in control brain. The present study demonstrated increased formation of eicosanoids, E(2)/D(2)-IsoPs, and docosanoids following cerebral ischemia. A balance of these lipid mediators may mediate immediate events of ischemic injury and recovery.

Different magnetic resonance imaging features in two types of nontraumatic rabbit osteonecrosis models

A single injection of high-dose steroid (20 mg/kg) has been reported to induce necrotic lesions in the proximal metaphysis and diaphysis of the rabbit femur. In the rabbit osteonecrosis (ON) model induced by two-dose horse serum injections, contrast-enhanced magnetic resonance imaging (MRI) and T2*-weighted dynamic MRI have been reported to detect necrotic lesions at 3 days after the second serum injection sensitively. The purpose of the present study was to determine whether contrast-enhanced MRI and T2*-weighted dynamic MRI could detect early development of necrotic lesions in the rabbit proximal femora after a single high-dose steroid injection and compare MRI features of the two types of nontraumatic rabbit ON models. We performed nonenhanced MRI, contrast-enhanced MRI and T2*-weighted dynamic MRI of bilateral proximal femora 3 days (10 femora), 1 week (10 femora), 3 weeks (10 femora), 6 weeks (18 femora) and 9 weeks (18 femora) after a single 20 mg/kg steroid injection. Femoral signal intensity of each T2*-weighted dynamic MRI was measured from a 1-cm(2) region of interest in the proximal metaphysis and diaphysis. As a control, MRI was performed in untreated animals (six femora). Histologically, no necrotic lesions were observed in the proximal femora at 3 days and 1 week. Bone marrow necrosis was observed in four (40%) femora at 3 weeks, two (11.1%) femora at 6 weeks and six (33.3%) femora at 9 weeks. Bone marrow lesion completely replaced by granulation tissue was observed in one femur at 6 weeks and one femur at 9 weeks. Histologic evidence of repair tissue surrounding bone marrow necrosis was seen after 6 weeks. Average lesion area including repair tissue was 4.40 mm(2) (range, 0.32 to 20.2 mm(2)). At 9 weeks, contrast-enhanced MRI could detect four (66.7%) femora with bone marrow necrosis of more than 4 mm(2) in the lesion area, while T2*-weighted dynamic images showed a finding of complete ischemia in only one of these four femora. In conclusion, neither contrast-enhanced MRI nor T2*-weighted dynamic MRI could detect early development of necrotic lesions in the single-dose steroid ON model. These results indicated that development of necrotic lesions in the single-dose steroid ON model was not accompanied by as diffuse a femoral hemodynamic change as the two-dose horse serum ON model.

ICU Controlled Delay for Acute Type A Aortic Dissection Repair after Intervention for Total Visceral Malperfusion: A Way Out of a Dilemma?

Despite immediate surgical repair of the entry site in acute thoracic aortic dissection with visceral malperfusion, the results are poor. Primary restitution of visceral flow by intervention might be one way to cope with this problem, but probably causes ischemia/reperfusion associated problems after prolonged complete visceral ischemia. In this report, we demonstrate a successful attempt of controlled delay of thoracic aortic surgical repair after visceral flow restitution with stable hemodynamics.

Effect of profound hypothermia on genomics of hippocampus following complete cerebral ischemia in rats

Objective: To determine differential gene expression of hippocampus in rats following complete cerebral ischemia with treatment of profound hypothermia compared to normothermia.Methods: Six rats got 5 minutes of complete cerebral ischemia with circulatory arrest and randomly divided into two groups: normothermia ischemia group (37 ± 0.3°C, n=3) and profound hypothermia ischemia group (18 ± 0.5°C, n=3). Affymetrix U34A rat arrays were applied to detect the difference of gene expression profile in hippocampus between the two groups.Results: Expression profiles of a total of 75 transcripts in the profound hypothermia ischemia group were statistically different from those of the normothermia ischemia group, and 33 of them were significantly up-regulated and other 42 were significantly down-regulated (p<0.01).Conclusions: Compared with normothermia, profound hypothermia had a significant effect on the gene expression profiles following complete cerebral ischemia, which may be involved in the mechanisms of cerebral protection by profound hypothermia.

The Effect of Direct Hemoperfusion with a Polymyxin B-Immobilized Fiber Column (DHP-PMX Therapy) on Pulmonary Ischemia-Reperfusion Injury in a Canine Model

This study evaluates the effectiveness of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) on warm ischemia-reperfusion injury of the lung using a canine mode.Materials and Methods: Ten adult mongrel dogs weighing 13–16 kg were used. After a left thoracotomy, the left pulmonary artery and vein were clamped. The left main bronchus was also clamped and then divided, and complete ischemia of the left lung was maintained for 3 h. The left main bronchus was re-anastomosed before reperfusion of the left lung. The right pulmonary artery was ligated immediately after reperfusion of the left lung. The dogs were divided into two groups: the DHP-PMX group (n = 5, DHP-PMX was performed for 120 min, from 30 min before reperfusion to 90 min after reperfusion) and the control group (n = 5). The body temperature of the animals was maintained at 36°C–37°C during the experiment. The PaO2/FiO2 (P/F ratio), AaDO2, and lt-pulmonary vascular resistance (PVR) were measured at 30, 60, 120, 180, and 240 min after reperfusion in both groups, and the two groups were compared. The water content of the lung tissues and histopathology was also analyzed. Results: The P/F ratio decreased remarkably after reperfusion in the control group, and was significantly (p <. 05) lower than that in the PMX-DHF group until 240 min after reperfusion. The AaDO2 was significantly (p <. 05) lower in the DHP-PMX group than in the control group at 30, 60, and 120 min after reperfusion. The lt-PVR level differed significantly (p <. 05) between the two groups until 240 min after reperfusion. The water content in the control group was significantly (p <. 05) higher than that in the DHP-PMX group at 240 min after reperfusion. Lung tissues at 120 and 240 min after reperfusion were better preserved pathologically in the DHP-PMX group. Conclusion: DHP-PMX therapy reduced warm ischemia-reperfusion injury in the lung using a canine model.

Real-Time Direct Measurement of Spinal Cord Blood Flow at the Site of Compression

An in vivo study to measure rat spinal cord blood flow in real-time at the site of compression using a newly developed device. To evaluate the change in thoracic spinal cord blood flow by compression force and to clarify the association between blood flow recovery and motor deficiency after a spinal cord compression injury. Until now, no real-time measurement of spinal cord blood flow at the site of compression has been conducted. In addition, it has not been clearly determined whether blood flow recovery is related to motor function after a spinal cord injury. Our blood flow measurement system was a combination of a noncontact type laser Doppler system and a spinal cord compression device. The rat thoracic spinal cord was exposed at the 11th vertebra and spinal cord blood flow at the site of compression was continuously measured before, during, and after the compression. The functioning of the animal's hind-limbs was evaluated by the Basso, Beattie and Bresnahan scoring scale and the frequency of voluntary standing. Histologic changes such as permeability of blood-spinal cord barrier, microglia proliferation, and apoptotic cell death were examined in compressed spinal cord tissue. The spinal blood flow decreased on each increase in the compression force. After applying a 5-g weight, the blood flow decreased to <40% of the precompression level. Complete ischemia was reached using a 20-g weight. After decompression, the blood flow level in the 20-minute complete ischemia group was significantly higher than that in the 40-minute complete ischemia group. The hind-limb motor function in the 40-minute complete ischemia group was significantly less than that in the sham group (without compression), while no significant difference was observed between the 20-minute ischemia group and the sham group. In the 20-minute ischemia group, the rats whose spinal cord blood flow recovery was incomplete showed significant motor function loss compared with rats that completely recovered blood flow. Extensive breakdown of blood-spinal cord barrier integrity and the following microglia proliferation and apoptotic cell death were detected in the 40-minute complete ischemia group. Duration of ischemia/compression and blood flow recovery of the spinal cord are important factors in the recovery of motor function after a spinal cord injury.

Characterization of the eIF2-associated protein p67 during brain ischemia and reperfusion

Objectives: Within the first few minutes of reperfusion after global brain ischemia, there is a severe depression of protein translation owing to phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2). There is a 67 kDa peptide (p67) that, in its glycosylated form, binds to eIF2 and protects eIF2α from phosphorylation. Moreover, cells with high p67 content exhibit enhanced resistance to eIF2α phosphorylation. To examine the possibilities that deglycosylation of brain p67 occurs during ischemia and/or early reperfusion or that p67 deglycosylation may be more extensive in the vulnerable neurons, these experiments were undertaken to characterize the localization and activation state of p67 during early brain reperfusionMethods: Western blots using antibodies that recognize total p67, glycosylated p67 and phosphorylated eIF2α were used to characterize total p67 and glycosylated p67 during reperfusion-induced phosphorylation of eIF2α. We also characterized the immunohistochemical distribution of glycosylated p67 before and after brain ischemia and reperfusion.Results: There was a large increase in phosphorylated eIF2α, but there was no decrease in the levels of total or glycosylated p67 from those observed in controls following 10 minutes complete brain ischemia and 10 or 60 minutes subsequent reperfusion. Furthermore, there was no reduction in localized immunostaining for glycosylated p67 in vulnerable neurons during ischemia and reperfusion.Discussion: It does not appear that p67 plays a significant role in regulating the phosphorylation of eIF2α following transient brain ischemia.

A novel model of acute murine hindlimb ischemia

The McGivney hemorrhoidal ligator (MHL), a band designed to cause tissue necrosis, is the preferred experimental tool to create hindlimb ischemia-reperfusion (I/R) injury in rodents. This report defines and compares the ex vivo band tension exerted by MHL and orthodontic rubber bands (ORBs) along with select in vivo characteristics of I/R. As to method, ex vivo band tension was measured over relevant diameters using a tensiometer. In vivo assessment of murine limb perfusion during ischemia with ORB and MHL was compared using laser Doppler imaging and measurement of wet weight-to-dry weight ratio. Neuromuscular scoring and histological extent of muscle fiber injury after I/R with MHL and ORB were also compared. A dose-response curve, between the duration of ORB-induced I/R with both mitochondrial activity (methyl-thiazol-tetrazolium) or tail perfusion [laser Doppler imaging (LDI)], was generated. As a results, ex vivo measurements showed that ORB exerted significantly less force than the MHL. Despite less tension in ORB, in vivo testing of the ORB confirmed complete ischemia by both LDI and wet weight-to-dry weight ratio. After I/R, caused by ORB, there was significantly less neuromuscular dysfunction. Histological assessment confirmed similar degrees of muscle fiber injury after I/R with either the MHL or ORB. Increasing durations of ischemia created by the ORB followed by reperfusion significantly decreased mitochondrial activity and tail perfusion after 24 h of ischemia. In conclusions, ORB produced similar levels of tissue ischemia in murine models of limb I/R with fewer levels of nonspecific injury. ORB may be the preferred model for selected studies of limb I/R.

Detection of Lower Torso Ischemia by Near-Infrared Spectroscopy During Cardiopulmonary Bypass in a 6.8-Kg Infant With Complex Aortic Anatomy

Neonates and small infants with congenital heart disease and complex cardiac and vascular anatomy are particularly prone to episodes of complete or incomplete regional ischemia during cardiopulmonary bypass. These episodes may result either from inhomogeneous distribution of arterial blood flow via the aortic cannula or from impaired drainage of blood via the venous cannulae. However, techniques for continuous routine monitoring of regional perfusion in neonates or small infants undergoing cardiopulmonary bypass are extremely limited. Over recent years, transcranial near-infrared spectroscopy has become established as a useful technique for the non-invasive monitoring of cerebral oxygenation. Here we present a case in which simultaneous near-infrared spectroscopic monitoring of the oxygenation status in the brain and the right upper thigh revealed lower torso ischemia due to accidental cross-clamping of a hypoplastic descending aorta which would otherwise have been unnoticed. This shows that parallel near-infrared spectroscopy of the brain and the lower extremities may represent a novel non-invasive monitoring technique to ensure adequate cerebral and extracerebral perfusion during cardiopulmonary bypass.

A novel model of acute murine hind limb ischemia

I. Introduction: The McGivney Hemorrhoidal Ligator band (MHL) is an established model of tourniquet induced hind-limb ischemia-reperfusion (IR) injury in rodents. The MHL model has been criticized for its inability to control for confounding factors such as crush injury and neurological damage to the area directly below the rubber band. This problem may be avoided, if complete hind-limb ischemia could be induced with minimal tension. These experiments were designed to (1) define and compare the ex-vivo force generated by the MHL as compared to Orthodontic Rubber Bands (ORB) of different diameters over a 3 hour period; (2) determine whether MHL and ORB create similar grades of in-vivo limb ischemia as measured by Laser Doppler Imaging (3); correlate the tension produced by the MHL and ORB with neurological assessment of murine hind limbs. The overall goal of these experiments is to determine whether orthodontic rubber bands (ORBs) provide an alternate, specific model of complete hind-limb ischemia by generating significantly less force and non-specific neurologic injury than previously established models. II. Methods: Ex- vivo force measurements were performed on 1/8” internal diameter 4.0 oz. ORB and MHL by mounting the bands on circular rods of varying sizes (0.86 and 1.04 cm), secured onto a magnetic-based micromanipulator. Force was then measured using a tensiometer which stretched each mounted band exactly 1 mm. Measurements were done in duplicate and the bands remained on the rods for 90 minutes to evaluate force decay. The in-vivo consequences of limb ischemia documented by applying ORBs and MHL to the hind limbs of anesthetized C57BL6 mice (25-30g, which were then scanned with Laser Doppler Imaging to confirm ischemia for at least 90 minutes. Once complete ischemia was confirmed for 90 minutes, the limbs were reperfused for 24 hours and subjected to neurologic scoring (paralysis, gait) by two blinded observers. III. Results: The force generated by the 4 oz. ORBs and MHL bands were significantly different (MHL: 0.28 + 0.009 vs. ORB: 0.08 + 0.002 kg, p= 0.0079) at 90 minutes. Variations in rod diameter (0.86 vs. 1.04 cm), did not affect the amount of force applied by the 4 oz ORB (p = .5141); In contrast, the force applied by the MHL varied significantly between these two measured diameters (p=0.0248). There was no significant decay in the force applied by the 4.0 oz. ORB up to 90 minutes (p = 0.1862); whereas the MHL showed significant force decay (p=0.0085). Absolute flux measurements compared to baseline perfusion, using LDI showed significant reduction in flow for both the 4 oz. (n = 10, p < 0.0001) ORB and MHL (n = 10, p < 0.0001). Furthermore, the degree of ischemia was equivalent in both ORB and MHL mice-(MHL: 50.1 + 5.6 vs. ORB: 36 + 6.3 flux units, p = 0.1431). At 24 hours reperfusion, the neurological score in MHL mice was significantly worse than ORB mice (MHL: 2.9 + 0.1, ORB: 1.8 + 0.3, p = 0.0137). IV. Conclusion: MHL bands deliver erratic and excessive force to create limb ischemia in rodents. The excessive force may promote non-ischemic neurologic injury, which may be related primarily to crush injury. The ORB provides and attractive alternative to the MHL, and thus may decrease experimental artifacts in studies of rodent hind limb ischemia reperfusion.

Increased Behavioral and Histological Variability Arising From Changes in Cerebrovascular Anatomy of the Mongolian Gerbil

The Mongolian gerbil (Meriones unguiculatus) has been used extensively as a model of forebrain ischemia. Its unique susceptibility to ischemia was suggested to be due to an incomplete circle of Willis. The relative ease to which ischemia can be induced combined with highly reproducible delayed CA1 cell death following a 5 min occlusion made the model popular in neuroprotection studies. Presently, this assumption was tested that complete forebrain ischemia occurs in all gerbils because increased variability was noticed in neuronal injury and behavioral outcome using this model in the last several years. Here it is reported that gerbils obtained from Charles River, the largest supplier in North America, show a high incidence (22.7% with bilateral and 38.6% with unilateral anastomoses) of posterior communicating arteries compared to another supplier of gerbils (High Oak Farms, 2.6% with bilateral and 13.2% with unilateral anastomoses, P<0.0001). This increased incidence of complete or partial circle of Willis led to less severe CA1 cell loss in Charles River gerbils (P<0.0001) compared to High Oak gerbils, with an unacceptably high level of inter-animal variability. Similarly, behavioral indices of CA1 ischemic injury (increased locomotion, habituation deficits) were also significantly attenuated in the Charles River animals. High Oak gerbils also displayed increased histological and behavioral variability relative to the pattern obtained several years ago. Thus, the gerbil model of forebrain ischemia, at least using Charles River animals, no longer produces consistent injury and behavioral alterations. Investigators are urged to consider adopting other models in future neuroprotection studies or ensure that their gerbil population lacks communicating arteries.

The inhibition of apoptosis in swine brain by hyperbaric oxygen therapy following cardiopulmonary arrest

Study objectives: It has been demonstrated that 4 atmospheres of hyperbaric oxygen therapy delivered after a 25-minute cardiopulmonary arrest in swine has produced immediate and sustained (2 hours) spontaneous return of circulation. Recent studies have shown that hyperbaric oxygen can improve neurologic recovery in cerebral ischemia models, but the mechanism remains controversial. This study tested the hypothesis that hyperbaric oxygen therapy delivered during cardiopulmonary resuscitation after a 25-minute cardiac arrest in swine would result in an attenuation of cerebral cortical apoptosis compared with animals resuscitated at surface pressure. Methods: Eighteen adolescent swine were anesthetized and underwent induced cardiac arrest for 25 minutes, producing a model of complete global ischemia. The animals were randomized to 3 groups, representing 3 pressures of oxygen ventilation provided during the cardiopulmonary resuscitation of the swine. Six animals per group received oxygen ventilation at surface pressure, 2 atmospheres, or 4 atmospheres. After 2 hours of resuscitation, the animals' brains were harvested and flash frozen in liquid nitrogen. The degree of apoptosis in each sample of cerebral cortex was determined through the measurement of DNA laddering, caspase-3 activity, poly(adenosine diphosphate ribose) polymerase (PARP) expression, and nucleosome cleavage. The average degree of apoptosis of the 3 groups was compared. Results: The relative density of PARP (caspase-3 substrate) was smaller in the group treated at surface depth (5.71) than in the 2-atmosphere group or the 4-atmosphere group (8.39 and 8.63, respectively; P =.04). There was no evidence of DNA laddering in any animals in group 3 (4 ATA), whereas 2 animals in group 1 (surface pressure) and 1 animal in group 2 (2 ATA) showed evidence of DNA laddering. Relative caspase-3 activity in the 4-ATA, 2-ATA, and surface-treated animals was 0.0327, 0.0402, and 0.0407 units/μg protein, respectively, whereas the relative quantity of nucleosome cleavage in the same groups was 0.108, 0.137, and 0.140 Abs[ 405 492 ], respectively (no statistical significance). Conclusion: The groups receiving hyperbaric oxygen therapy showed less apoptosis than the group treated at surface pressure, as measured by PARP cleavage. A similar trend exists as measured by the other tests (DNA laddering, caspase-3 assay, nucleosome enzyme-linked immunosorbent assay).

Popliteal artery aneurysms from a vascular surgeon's point of view

Popliteal artery aneurysms (PAA) are a dangerous complication of general atherosclerosis or other diseases. PAAs with a diameter of less than 2 cm are observed despite the fact that small aneurysms may also result in peripheral embolism. The spectrum of complications in the course of the disease ranges from multiple embolism into the crural arteries or complete thrombosis of the popliteal artery associated with complete ischaemia. Rupture is rare even in large aneurysms. Interventional therapy using covered stents does not lead to results comparable with surgery and is not considered as standard therapy. Surgical technique in asymptomatic aneurysms includes resection/exclusion of the PAA with reversed vein PI-PIII vein bypass. In case of acute ischaemia the therapy has to be modified according to anatomic aspects and has to be combined in some cases with intraoperative lysis. Amputation rate may be as high as 40%. Large aneurysms (>3 cm) should be treated by aneurysmorrhaphy or resection with graft interposition rather than simple bypass. In our study with short follow-up only 3 of 10 patients were asymptomatic. Survival rate, limb salvage and patency amounted to 100%.

Targeting of the vascular system of solid tumours by photodynamic therapy (PDT).

Owing to morphological and rheological differences of the tumour vascular system as compared to the vascular system of the surrounding tissue, the efficacy of several experimental and clinical therapeutic approaches is limited. This fact has put the vascular system of solid tumours into focus and two new therapeutic strategies, anti-angiogenesis and vascular targeting, have emerged. Under the term vascular targeting various therapeutic approaches are summarized, e.g. chemoembolization, chemotherapy, hyperthermia, vascular targeting agents (VTA) and photodynamic therapy (PDT). As shown using the clinically approved photosensitiser Photofrin the irreversible destruction of the tumour vascular system is primarily responsible for an effective PDT of solid tumours. However, the clinical disadvantages of Photofrin are well known. Thus, several new photosensitisers, e.g. aminolaevulinic acid (ALA), porphycenes and indocyanine green (ICG), have been evaluated in vitro and in vivo regarding their suitability for vascular targeting of solid tumours. The promising experimental findings with the photosensitiser ICG led to first clinical results in treating Kaposi's sarcomas. In summary, systemic PDT is only effective when leading to complete ischaemia of solid tumours with subsequent necrosis. An essential prerequisite is the use of a chemically and photophysically defined photosensitiser localizing in the intravascular space due to e.g. a high molecular weight. The specific properties of such a photosensitiser are outlined.

Prevention of ischaemia-induced small intestinal adhesions in foals.

Treatments addressing variously theorised pathophysiological mechanisms of small intestinal adhesions have been reported. This study applied those classes of treatments to the most clinically relevant aetiology of post operative adhesions. Treatments addressing the pathophysiology of ischaemia-reperfusion induced adhesions would accordingly reduce the incidence of adhesions from this model. Four classes of treatments were administered for 72 h to 16 foals subjected to complete ischaemia followed by reperfusion to create peritoneal adhesions. These groups were: 1) FPG group--flunixin meglumine (1.1 mg/kg bwt i.v., divided q.i.d.), potassium penicillin G (22,000 iu/kg bwt i.v., q.i.d.) and gentamicin (2.2 mg/kg bwt i.v., t.i.d.); 2) HEP group--heparin (80 iu/kg bwt subcut., b.i.d.); 3) DMSO group--dimethylsulphoxide (DMSO) (20 mg/kg bwt [diluted in 500 ml normal saline] i.v., b.i.d.); and 4) SCMC group--sodium carboxymethylcellulose (500 ml 3% sterile solution intraperitoneally, administered only at the beginning of surgery). Post operative intestinal obstruction did not occur in any foal. After 10 days, necropsy revealed bowel-to-bowel adhesions in none of the FPG or DMSO groups, in 2/4 of the SCMC group, in 3/4 of the HEP group and 5/6 foals subjected to the procedure without treatment (UIR group). Inhibition of the inflammation associated with ischaemia and reperfusion in foals treated with FPG or DMSO decreased small intestinal adhesions in foals. Although anti-inflammatory therapy was shown to eliminate bowel-bowel adhesions in this controlled study, it must be remembered that clinical cases are without control. These therapies are advised to improve the result but are unlikely to eliminate the problem.

Ischemia Induces Hsp70 Expression In Porcine Skeletal Muscle

2184 Ischemia causing a series of cellular changes is known to induce Heat-Shock-Protein70 (HSP70) in different tissues i.e. myocardium, brain, kidney and liver as shown in prior studies. It has been documented that HSP70 induction has protective effects against ischemic damage in these tissues. In a previous study on patients with peripheral arterial occlusive disease we observed an increased expression of HSP70 in involved muscles. This might suggest that ischemia in skeletal muscle induces HSP70 expression. Purpose: To investigate whether ischemia induces HSP70 expression in skeletal muscle. Methods: 21 3–4 months old swines were taken for the experiment. Complete ischemia was obtained by arterial ligation. Muscle biopsies were taken from the M. sternocleidomastoideus before ischemia (Normoperfusion, I0), after 2h of ischemia (I2) and after 4h of ischemia (I4). Total protein was extracted and after protein separation by SDS-PAGE HSP70 protein level was quantitated using Western Blot and densitometric analysis. Quantitative real-time RT-PCR was used to assess HSP70 mRNA level. Results: In comparison to I0 (34,9 ng for 25 ug protein loaded) HSP70 protein level showed a slight increase (N.S.) after 2h ischemia (37,5 ng) and an additional low increase after 4h ischemia (41,1 ng). However relative HSP70 mRNA concentration is clearly elevated in I2 (by 2,5 folds, p = 0,13) and there was a further significant upregulation in I4 compared to I0 (4,3 folds, p<0,05). Conclusion: The present study has demonstrated for the first time that ischemia can cause an upregulation of HSP70 expression in skeletal muscle. The lack of significant increase in HSP70 protein level may be attributed to reduced protein synthesis rate under ischemia. Therefore HSP70 induction might be considered as a stress indicator for the case of ischemia. Whether HSP70 upregulation can provide protection against ischemia in skeletal muscle as it has been shown in myocardium, requires further study.

Blunt popliteal artery injury with complete lower limb ischemia: is routine use of temporary intraluminal arterial shunt justified?

Objective Complete lower limb ischemia as a result of blunt popliteal artery injury is associated with the highest morbidity and amputation rates among all of the peripheral vascular injuries. The purpose of this study was to determine the possible benefits of routine use of a temporary intraluminal arterial shunt in patients with complete limb ischemia from blunt popliteal trauma. Patients and methods Over 3 years seven blunt popliteal artery injuries with complete lower limb ischemia were managed with insertion of a shunt at the initial phase of the operation. Data from these procedures was analyzed and compared with retrospectively collected data for 10 injuries with complete ischemia treated without shunts during the preceding 5 years. Results Mean injury severity score and mangled extremity severity score were 9.3 ± 3.49 and 5.7 ± 0.95, respectively, in the shunt group, and 9.9 ± 3.57 and 5.9 ± 0.56, respectively in the non-shunt group. Mean ischemic time was 244.3, 24.3, and 268.6 minutes, respectively, for preoperative, intraoperative, and total ischemic time in the shunt group, and 273, 56.5, and 329.5 minutes in the non-shunt group. The difference was significant for intraoperative ( P < .001) and total ( P < .05) ischemic time. In the entire group, 92.8% of patients with total ischemic time greater than 4 hours underwent fasciotomy, 100% required repeat operation, and 57.1% had complications and required fasciotomy wound debridement. All patients (100%) with ischemic time greater than 6 hours required amputation, compared with no patients with ischemic time less than 5 hours. One patient in the shunt group (14.3%) experienced one fasciotomy wound complication (11.1%), compared with seven patients in the non-shunt group (70%) had 8 complications (88.9%) ( P < .05). Mean number of repeat operations was 0.8 ± 1.06 in the shunt group, and 1.9 ± 0.73 in the non-shunt group ( P < .05). One patient in the shunt group (14.3%) required fasciotomy wound debridement, compared with seven patients in the non-shunt group (70%; P < .05). Mean hospital stay was 14.4 and 23 days, respectively, in the shunt and non-shunt groups ( P < .05). Four limbs in the non-shunt group (40%) required amputation, compared with 100% limb salvage in the shunt group. Conclusion Temporary arterial shunting after blunt lower limb trauma significantly reduces total ischemic time, complications, repeat operations, amputation, and hospitalization. I recommend routine use of shunts in blunt popliteal artery injuries with complete lower limb ischemia.

Alterações metabólicas induzidas por isquemia hepática normotérmica experimental e o efeito hepatoprotetor da ciclosporina

Hepatic transplantation is inevitably associated with periods of complete ischemia. However, the clamping of hepatic vascular pedicle is limited by the consequences of the post-ischemic injury to the liver. To determine the main metabolic alterations caused for the hepatic ischemia and the probable hepatoprotective effect cyclosporin. Normothermic hepatic ischemia during 60 minutes was induced in the rats. The time-course (0, 1, 6, 24 hours) of changes in blood and in the hepatic concentrations of lactate, pyruvate, glucose, ketone bodies and in the ratio of acetoacetate/3-hydroxybutyrate, as well as the cytoplasmic and mitochondrial redox state of the liver cells were determined. A group of animals was daily pre-treated with cyclosporine (10 mg/kg) during 4 days until the induction of hepatic ischemia, then they studied 1 hour after hepatic revascularization. Hepatic ischemia caused elevation in the concentrations of lactate in the liver, suggesting that a pronounced level of anaerobic metabolism occurred during the ischemia period. Liver ischemia promoted yet a fall in the concentration and in the ratio of ketone bodies (acetoacetate/3-hydroxybutyrate) in the arterial blood in the studied period of one hour post-revascularization, perhaps reflecting impairment of ketogenesis as a result of the ischemic injury. The treatment with cyclosporine cause elevation in the concentration of ketone bodies and in the ratio of acetoacetate/3-hydroxybutyrate in the arterial blood 1 hour after reperfusion of the liver, suggesting that these drugs may accelerate the recovery of the ischemic hepatic lesion with reactivation of ketogenesis.

Arteria-poplitea-Aneurysmen aus gefäßchirurgischer Sicht

ZusammenfassungArteria-poplitea-Aneurysmen (PAA) stellen eine gefährliche Komplikation der Arteriosklerose (oder anderer Grunderkrankungen) dar. Asymptomatische Aneurysmen &lt;2 cm im Durchmesser werden zumeist beobachtet, obwohl auch sie zur Embolisation führen können. Zum Spektrum der PAA-Komplikationen gehört die multiple Embolisation in die Unterschenkelarterien oder die Querschnittsthrombosierung des Aneurysmas mit oder ohne komplette Ischämie. Die Ruptur ist auch bei großen Aneurysmen eher selten. Eine interventionelle Therapie von PAA mit beschichteten Stents ist wegen ungünstiger Offenheitsraten noch nicht als Standard anzusehen. Die chirurgische Therapie besteht bei asymptomatischen Aneurysmen in einer Resektion/Exclusion mit Anlage eines PI-PIII-Bypass, bei symptomatischen oder thrombosierten Aneurysmen muss eine der Morphologie angepasste Therapie (z. B. kruraler Venen-Bypass) mit oder ohne Lyse erfolgen. Große Aneurysmen werden in der Regel durch Aneurysmorrhaphie bzw. Resektion und Interponat behandelt. Eingriffe im Notfall sind mit einer Amputationsrate bis 40% assoziiert. In der vorgestellten Serie mit kurzem Follow-up waren drei von zehn Patienten asymptomatisch. Die Überlebens- und Beinerhaltungsrate sowie Bypassdurchgängigkeit betrug 100%.

Metabolic Alterations of Skeletal Muscle Tissue After Prolonged Acute Ischemia and Reperfusion

Acute tissue ischemia is usually followed by considerable disturbances of cellular metabolism that often lead to cell death. Reperfusion improves cellular function by withdrawing the toxic products of ischemia and providing energy sources, although sometimes it worsens it. The purpose of this experimental work is to study the metabolic disturbances in skeletal muscle tissue of canines after prolonged acute ischemia in relation to the values of certain substances (ATP, lactate, pyruvate, the ratio of lactate to pyruvate [L/P], and glucose) and whether the alterations in the values of these substances could be used as prognostic indices of the magnitude of tissue damage and the possibility of inverting it. We used 15 mongrel dogs. Complete acute ischemia was induced in the right lower limb lasting 12 h. Reperfusion also lasted for 12 h. The left lower limb was used as reference value. Before the beginning of ischemia, at (1/2), 1, 6, and 12 h after the induction of ischemia, and at (1/2), 1, 6, and 12 h after the restoration of circulation, blood samples, and tissue biopsies were obtained from the healthy and the experimental limb for the measurement of ATP, lactate, pyruvate, the ratio of L/P, and glucose. From the statistical analysis of the values of the controlled parameters the following were concluded: The changes in ATP, lactate, pyruvate, and the L/P ratio in the venous blood of the experimental limb and in the intracellular space of the suffering skeletal muscle could be used as indices to evaluate ischemic injury to the skeletal muscles, the course of its development, and the possibility of reversal after reperfusion.