Hours Of Ischemia Research Articles

Toll-Like Receptor 9 Inhibition Confers Protection From Liver Ischemia–Reperfusion Injury

Endogenous ligands such as high-mobility group box 1 (HMGB1) and nucleic acids are released by dying cells and bind Toll-like receptors (TLRs). Because TLR9 sits at the interface of microbial and sterile inflammation by detecting both bacterial and endogenous DNA, we investigated its role in a model of segmental liver ischemia-reperfusion (I/R) injury. Mice were subjected to 1 hour of ischemia and 12 hours of reperfusion before assessment of liver injury, cytokines, and reactive oxygen species (ROS). Wild-type (WT) mice treated with an inhibitory cytosine-guanosine dinucleotide (iCpG) sequence and TLR9(-/-) mice had markedly reduced serum alanine aminotransferase (ALT) and inflammatory cytokines after liver I/R. Liver damage was mediated by bone marrow-derived cells because WT mice transplanted with TLR9(-/-) bone marrow were protected from hepatic I/R injury. Injury in WT mice partly depended on TLR9 signaling in neutrophils, which enhanced production of ROS, interleukin-6 (IL-6), and tumor necrosis factor (TNF). In vitro, DNA released from necrotic hepatocytes increased liver nonparenchymal cell (NPC) and neutrophil cytokine secretion through a TLR9-dependent mechanism. Inhibition of both TLR9 and HMGB1 caused maximal inflammatory cytokine suppression in neutrophil cultures and conferred even greater protection from I/R injury in vivo. TLR9 serves as an endogenous sensor of tissue necrosis that exacerbates the innate immune response during liver I/R. Combined blockade of TLR9 and HMGB1 represents a clinically relevant, novel approach to limiting I/R injury.

The Effect of Ischemic Preconditioning on Secondary Ischemia in Myocutaneous Flaps

We sought to determine the effect of ischemic preconditioning (IPC) on secondary ischemia in myocutaneous flaps in a rat model. Forty rectus abdominis myocutaneous flaps were elevated in 40 rats, and the animals were randomized into control or IPC groups (20 flaps each group). All flaps were then subject to primary ischemia for 2 hours via pedicle clamping. Twenty-four hours later, the control and IPC flaps were randomized to two groups each of 1 or 2 hours of secondary ischemia (4 groups, 10 flaps per group). Flap survival was evaluated on postoperative day 5 by measuring the percentage area of flap survival by a blinded observer. Mean flap survival area and total necrosis rates were compared between the groups. In the 1-hour secondary ischemia groups, IPC improved mean flap survival area from 11 +/- 7% to 36 +/- 22%, and the total necrosis rates from 40 to 0%. These differences were statistically significant (p < 0.006, p < 0.05, respectively). In the 2-hour secondary ischemia groups, differences were not statistically significant (p = 0.2, p = 0.4, respectively). IPC improves the survival of myocutaneous flaps subjected to secondary ischemia of 1 hour in this rat free flap model.

The Effect of Adipose-Derived Stem Cells on Ischemia-Reperfusion Injury: Immunohistochemical and Ultrastructural Evaluation

Advances in the treatment of reperfusion injury have created an opportunity for plastic surgeons to apply these treatments to flaps and implanted tissues. The authors examined the direct and indirect effects of adipose-derived stem cells on ischemia-reperfusion injury on a skin flap model to determine the in vivo differentiation of adipose-derived stem cells to endothelial cells; the levels of vascular endothelial growth factor (VEGF), transforming growth factor-beta, and fibroblast growth factor; and the ultrastructural changes apparent with scanning electron microscopy to clarify the initial events and the following cascades. Two identical cranial based random flaps with a dimension of 1 x 5 cm were elevated on the dorsums of 20 ICR mice. The left flap was designated as the control and the right flap was injected with adipose-derived stem cells. The flaps were then subjected to 6 hours of ischemia by clamping the pedicle, and then reperfusion. The mean viable flap length in the control and experimental groups was 15.2 +/- 3.4 mm and 24.4 +/- 2.9 mm, respectively. The mean viable flap area in the control and experimental groups was 12.9 +/- 4.1 mm and 21.8 +/- 3.7 mm, respectively. The in vivo differentiation of adipose-derived stem cells to endothelial cells was observed. The immunohistochemical stainings, VEGF, transforming growth factor-beta, and fibroblast growth factor revealed increased levels in the experimental groups. Scanning electron microscopy indicated mild injury in the experimental group. The adipose-derived stem cells could prevent ischemia-reperfusion injury, mainly by regulating the growth factors. Although VEGF was the foremost inhibitor of injury, the overall cascade was enhanced by adipose-derived stem cells, with the help of the other growth factors.

Effect of firocoxib or flunixin meglumine on recovery of ischemic-injured equine jejunum

To determine whether treatment of horses with firocoxib affects recovery of ischemic-injured jejunum, while providing effective analgesia. 18 horses. Horses (n = 6 horses/group) received saline (0.9% NaCl) solution (1 mL/50 kg, IV), flunixin meglumine (1.1 mg/kg, IV, q 12 h), or firocoxib (0.09 mg/kg, IV, q 24 h) before 2 hours of jejunal ischemia. Horses were monitored via pain scores and received butorphanol for analgesia. After 18 hours, ischemic-injured and control mucosa were placed in Ussing chambers for measurement of transepithelial resistance and permeability to lipopolysaccharide. Histomorphometry was used to determine denuded villus surface area. Western blots for cyclooxygenase (COX)-1 and COX-2 were performed. Plasma thromboxane B(2) and prostaglandin E(2) metabolite (PGEM) concentrations were determined. Pain scores did not significantly increase after surgery in horses receiving flunixin meglumine or firocoxib. Transepithelial resistance of ischemic-injured jejunum from horses treated with flunixin meglumine was significantly lower than in saline- or firocoxib-treated horses. Lipopolysaccharide permeability across ischemic-injured mucosa was significantly increased in horses treated with flunixin meglumine. Treatment did not affect epithelial restitution. Cyclooxygenase-1 was constitutively expressed and COX-2 was upregulated after 2 hours of ischemia. Thromboxane B(2) concentration decreased with flunixin meglumine treatment but increased with firocoxib or saline treatment. Flunixin meglumine and firocoxib prevented an increase in PGEM concentration after surgery. Flunixin meglumine retarded mucosal recovery in ischemic-injured jejunum, whereas firocoxib did not. Flunixin meglumine and firocoxib were effective visceral analgesics. Firocoxib may be advantageous in horses recovering from ischemic intestinal injury.

Influence of L-arginine on the nitric oxide concentration and level of oxidative stress during ischemia-reperfusion injury in a rat model

This study aimed at evaluating whether supplementation of L-arginine in the course of ischemia and reperfusion syndrome after acute, experimental ischemia of the hind legs of the rat, could influence nitric oxide (NO) concentration and selected biochemical parameters concentration related to the oxidative stress. The study included 64 male Wistar rats. The animals were divided into four groups: Group I = control, Group II = placebo, Group III = L-arginine (500 mg/kg body mass/day for 5 days, p.o.), Group IV = L-arginine and nonspecific nitric oxide synthase (NOS) inhibitor - N(G)-Nitro-L-arginine-methyl ester (L-NAME) (75 micromol/ rat/day for 5 days, p.o.). Each group was further divided into subgroups: 1 = animals not subjected to ischemia and reperfusion, 2 = animals underwent 4-hour ischemia and subsequent reperfusion. Animals from Subgroup 2 were anesthetized and submitted to acute tourniquet ischemia of the hind limb. Blood samples were collected from all anesthetized rats by puncturing the right ventricle to assess total antioxidant status, lipids' peroxide concentration and nitric oxide concentration before ischemia and at 4th hour of ischemia and at 30th, 60th or 120th minute of reperfusion. We found that administration of L-arginine to rats resulted in significant increase of NO, level of total antioxidant status (TAS), and decrease of lipid' peroxide concentration when compared to the control and placebo groups. All these laboratory changes were progressing along with lengthening of reperfusion time. Simultaneous application of L-NAME led to reversal of phenomena caused by L-arginine. The present results suggest that L-arginine may protect tissues and organs against ischemia-reperfusion injury. The potential therapeutic role of L-arginine administration in prevention and treatment of ischemia-reperfusion syndrome consequences needs further investigation in humans.

Minocycline and Tissue-Type Plasminogen Activator for Stroke

New treatment strategies for acute ischemic stroke must be evaluated in the context of effective reperfusion. Minocycline is a neuroprotective agent that inhibits proteolytic enzymes and therefore could potentially both inactivate the clot lysis effect and decrease the damaging effects of tissue-type plasminogen activator (t-PA). This study aimed to determine the effect of minocycline on t-PA clot lysis and t-PA-induced hemorrhage formation after ischemia. Fibrinolytic and amidolytic activities of t-PA were investigated in vitro over a range of clinically relevant minocycline concentrations. A suture occlusion model of 3-hour temporary cerebral ischemia in rats treated with t-PA and 2 different minocycline regimens was used. Blood-brain barrier basal lamina components, matrix metalloproteinases (MMPs), hemorrhage formation, infarct size, edema, and behavior outcome were assessed. Minocycline did not affect t-PA fibrinolysis. However, minocycline treatment at 3 mg/kg IV decreased total protein expression of both MMP-2 (P=0.0034) and MMP-9 (P=0.001 for 92 kDa and P=0.0084 for 87 kDa). It also decreased the incidence of hemorrhage (P=0.019), improved neurologic outcome (P=0.0001 for Bederson score and P=0.0391 for paw grasp test), and appeared to decrease mortality. MMP inhibition was associated with decreased degradation in collagen IV and laminin-alpha1 (P=0.0001). Combination treatment with minocycline is beneficial in t-PA-treated animals and does not compromise clot lysis. These results also suggest that neurovascular protection by minocycline after stroke may involve direct protection of the blood-brain barrier during thrombolysis with t-PA.

Experimental Model of Brainstem Stroke in Rabbits via Endovascular Occlusion of the Basilar Artery

Basilar artery thrombosis remains a significant clinical problem, and no reproducible animal model has been established to study the stroke within the vertebrobasilar distribution. We report a study designed to pilot test a novel model of brainstem stroke in rabbits, created by selective endovascular occlusion of the basilar artery. Basilar artery occlusion was induced in 8 New Zealand white rabbits by injection of the autologous clot through the microcatheter positioned within the distal vertebral artery. Animals were divided into subgroups (I and II) based on the length of produced ischemia (3 and 6 hours, respectively). Magnetic resonance (MR) imaging of the brain and MR angiography of the intracranial vessels were performed before the procedure, and at 3 hours after induced ischemia for groups I and II, with continued imaging up to 6 hours for group II, with diffusion-weighted images acquired approximately every 30 minutes. Animals were killed at the end of the 3-hour (group I) or 6-hour (group II) ischemia time. Brainstem stroke was successfully induced in all animals, with pathological changes documented in all cases. The earliest changes of ischemia on MR diffusion-weighted images were identified at only 4.5 hours of basilar artery occlusion. These results suggest that a reproducible model of brainstem stroke can be induced in rabbits using selective endovascular occlusion of the basilar artery. The availability of such a model, integrated with state-of-the-art imaging techniques, holds promise for preclinical investigations of emergent therapeutic approaches in stroke.

ERYTHROPOIETIN ENHANCES OXYGENATION IN CRITICALLY PERFUSED TISSUE THROUGH MODULATION OF NITRIC OXIDE SYNTHASE

The aim of this study was to investigate the effect of human recombinant erythropoietin (EPO) on the microcirculation and oxygenation of critically ischemic tissue and to elucidate the role of endothelial NO synthase in EPO-mediated tissue protection. Island flaps were dissected from the back skin of anesthetized male Syrian golden hamsters including a critically ischemic, hypoxic area that was perfused via a collateralized vasculature. Before ischemia, animals received an injection of epoetin beta at a dose of 5,000 U/kg body weight with (n = 7) or without (n = 7) blocking NO synthase by 30 mg/kg body weight L-NAME (Nomega-nitro-L-arginine methyl ester hydrochloride). Saline-treated animals served as control (n = 7). Ischemic tissue damage was characterized by severe hypoperfusion and inflammation, hypoxia, and accumulation of apoptotic cell nuclei after 5 h of collateralization. Erythropoietin pretreatment increased arteriolar and venular blood flow by 33% and 37%, respectively (P < 0.05), and attenuated leukocytic inflammation by approximately 75% (P < 0.05). Furthermore, partial tissue oxygen tension in the ischemic tissue increased from 8.2 to 15.8 mmHg (P < 0.05), which was paralleled by a 21% increased density of patent capillaries (P < 0.05) and a 50% reduced apoptotic cell count (P < 0.05). The improved microcirculation and oxygenation were associated with a 2.2-fold (P < 0.05) increase of endothelial NO synthase protein expression. Of interest, L-NAME completely abolished all the beneficial effects of EPO pretreatment. Our study demonstrates that, in critically ischemic and hypoxic collateralized tissue, EPO pretreatment improves tissue perfusion and oxygenation in vivo. This effect may be attributed to NO-dependent vasodilative effects and anti-inflammatory actions on the altered vascular endothelium.

Improved Survival of Murine Island Skin Flaps by Prevention of Reperfusion Injury

Studies have demonstrated that blocking a single specificity of self-reactive immunoglobulin M with a 12-amino acid peptide mimic of the antigen of immunoglobulin M can attenuate murine intestinal and skeletal muscle injury following ischemia and reperfusion. The aim of this study was to ascertain whether peptide (P8) had protective effects in an axial island skin flap model, where tissue loss is attributed to ischemia-reperfusion injury. Dorsal lateral thoracic artery island skin flaps (3.5 x 1.5 cm) were elevated in 82 male C57BL/6 mice and rendered ischemic for 10 hours by placing a 7-mm microclamp on the vascular pedicle followed by 7 days of reperfusion. Group I (n = 7), the sham group, had no clamp placed. Group II (n = 21) had clamp placement but no other treatment. Thirty minutes before clamp placement, group III (n = 18) received 0.25 cc of saline intravenously, group IV (n = 18) received 25 microg/0.25 cc P8 peptide, and group V (n = 7) received 25 microg/0.25 cc random 12-mer peptide. Animals in group VI (n = 11) underwent two cycles of 20 minutes of ischemic preconditioning before 10 hours of ischemia. After 1 week of reperfusion, percent necrosis was measured and results were compared using analysis of variance and an unpaired t test. In animals treated with P8 peptide, flap necrosis was 14.61 +/- 2.77 percent. This represents a statistically significant, 56 percent reduction in flap necrosis compared with controls (p < 0.001). These data demonstrate that prevention of ischemia-reperfusion injury with P8 peptide produces a significant reduction in necrosis of treated flaps.

Reactive Oxygen Species Mediate Liver Injury Through Parenchymal Nuclear Factor-κB Inactivation in Prolonged Ischemia/Reperfusion

Nuclear factor (NF)-kappaB participates in ischemia/reperfusion (I/R) hepatic signaling, stimulating both protective mechanisms and the generation of inflammatory cytokines. After analyzing NF-kappaB activation during increasing times of ischemia in murine I/R, we observed that the nuclear translocation of p65 paralleled Src and IkappaB tyrosine phosphorylation, which peaked after 60 minutes of ischemia. After extended ischemic periods (90 to 120 minutes) however, nuclear p65 levels were inversely correlated with the progressive induction of oxidative stress. Despite this profile of NF-kappaB activation, inflammatory genes, such as tumor necrosis factor (TNF) and interleukin (IL)-1beta, predominantly induced by Kupffer cells, increased throughout time during ischemia (30 to 120 minutes), whereas protective NF-kappaB-dependent genes, such as manganese superoxide dismutase (Mn-SOD), expressed in parenchymal cells, decreased. Consistent with this behavior, gadolinium chloride pretreatment abolished TNF/IL-1beta up-regulation during ischemia without affecting Mn-SOD levels. Interestingly, specific glutathione (GSH) up-regulation in hepatocytes by S-adenosylmethionine increased Mn-SOD expression and protected against I/R-mediated liver injury despite TNF/IL-1beta induction. Similar protection was achieved by administration of the SOD mimetic MnTBAP. In contrast, indiscriminate hepatic GSH depletion by buthionine-sulfoximine before I/R potentiated oxidative stress and decreased both nuclear p65 and Mn-SOD expression levels, increasing TNF/IL-1beta up-regulation and I/R-induced liver damage. Thus, the divergent role of NF-kappaB activation in selective liver cell populations underlies the dichotomy of NF-kappaB in hepatic I/R injury, illustrating the relevance of specifically maintaining NF-kappaB activation in parenchymal cells.

Transient benefits but lack of protection by sodium pyruvate after 2-hour middle cerebral artery occlusion in the rat

Sodium pyruvate has shown protective effects in various experimental models of brain ischemia. The main holdup of this drug is that most of the benefits are reported with a very narrow time window for intervention. Here we investigated whether pyruvate could protect the brain against ischemic damage using a model of 2-hour middle cerebral artery occlusion in the rat. The time course of blood pyruvate after i.p. administration of sodium pyruvate (400 mg/kg) was studied. Animals were treated with the drug or with vehicle 45 min after reperfusion following 2-hour ischemia. Tissue ATP content was determined 5 and 10 h after ischemia onset, and infarct volume was measured at days 1 and 2. The neurological score was evaluated before and after treatment in the different experimental groups. Pyruvate prevented the drop of cortical ATP induced by ischemia in the ipsilateral cortex and ameliorated the neurological deficit at 5 h after the onset of ischemia, supporting some beneficial effects of the treatment. However, these effects were not sustained at 10 h. Furthermore, pyruvate failed to significantly reduce infarct volume and the neurological deficit at 24 and 48 h, in spite of some trend to smaller infarction after pyruvate administration. Therefore, under the present experimental conditions, systemic administration of sodium pyruvate at 3 h after the beginning of ischemia exerted only a transient benefit but not a persistent protection against brain damage.

A Murine Model of Acute Hindlimb Ischemia/Reperfusion Injury

Introduction15% of preventable combat fatalities are due to hemorrhage from extremity wounds, making emergency tourniquet one of the first‐line treatments. While lifesaving, tourniquets can cause serious ischemia‐reperfusion (IR) injury. Fundamental to IR injury is mitochondrial production of superoxide. We refined a murine model of acute hind limb IR to simulate the clinical use of tourniquet.MethodsGroups of C57/BL6 mice underwent an IR protocol of three hours of ischemia and four hours of reperfusion. IR was achieved by placement and release of a rubber tourniquet around the hind limb, at the greater trochanter level. Muscle blood flow (MBF) was measured using a Doppler probe. Muscle necrosis was measured using TTC stain. Superoxide production was measured using chemiluminescence and DHE staining. MnSOD protein expression and activity were measured using Western blot and a modified nitrite method. Mitochondrial respiratory chain function was measured via spectrophotometry.ResultsSignificant ischemia and microcirculatory dysfunction were achieved: MBF during IR was &lt; 10% and &lt; 41% of baseline, respectively (n=8), accompanied by &gt;40% necrosis (n=9). Superoxide production was increased (0.05 vs 0.13, p&lt;.05 sham vs IR)accompanied by concomitant increases in MnSOD activity and protein expression (1.51 vs 2.26 , p&lt;.05,sham vs IR, n=8). Mitochondrial complexes I‐IV showed signs of dysfunction (Complex I‐ IV: 0.13, 0.31, 1.37, 2.76 sham vs 0.08, 0.21, 0.7, 1.97 IR, p&lt;.05 ).ConclusionsWe have demonstrated an animal model of clinical tourniquet use. IR produces significant mitochondriopathy which is associated with elevated superoxide production and antioxidant activity. The model can be used to mechanistically evaluate antiischemic molecules in efforts to minimize the morbidity and mortality of battlefield injury.

Effect of IIb-IIIa Glycoprotein Inhibitors in a Partial Limb Amputation Model Submitted to Warm Ischemia in Rats

Viability and functional results of a segment replantation depend on the prevention of deleterious effects of ischemia. Prolonged ischemia leads to alterations in the microcirculation: thrombosis, edema, production of oxygen free radicals, and platelet aggregation. The effect of IIb-IIIa glycoprotein inhibitors was tested in a partial limb amputation model submitted to warm ischemia. The male Wistar rats were divided into four groups: G1 with 0 hours of ischemia and saline ( N = 20), G2 with 6 hours of ischemia and saline ( N = 24), G3 with 6 hours of ischemia and abciximab ( N = 23), and G4 with 6 hours of ischemia and tirofiban ( N = 29). The limbs were observed for 7 days and classified as viable or nonviable. Viability and mortality rates were obtained and analyzed by Q-square and Fisher exact tests ( P < 0.05). The viability rates were 100% (G1), 30% (G2), 77.78% (G3), and 80.95% (G4). G2 was statistically different from G1, G3, and G4. G1, G3, and G4 were not statistically different. Transoperative and postoperative mortalities were not statistically different. The administration of abciximab and tirofiban improved limb salvage after ischemia and reperfusion and did not modify mortality rates significantly.

Increased Signs of Acute Rejection With Ischemic Time in a Rat Musculocutaneous Allotransplant Model

Background Composite tissue allotransplantation (CTA) may restore a variety of tissue defects, but carries the potential risks of graft failure and/or immunosuppression-related complications. Ischemia–reperfusion injury has been documented in CTA is known to contribute to acute rejection of solid organ grafts. This study describes the influence of subcritical ischemic time (ie, ischemia sufficient to generate reversible cell damage) on signs of rejection of musculocutaneous allograft components of subcritical ischemic time, namely, ischemia sufficient to generate reversible cell injury. Although skin is considered the most antigenic component of a composite allograft and is currently used for rejection surveillance, muscle and adipose are more susceptible to ischemia-related injury. Methods Vascularized epigastric flaps were transplanted from WKY to Fisher 344 rats after 1 or 3 hours of ischemia. Biopsies taken on postoperative day 6 were graded for signs of acute rejection according to criteria modified from previously published grading systems for CTA rejection. Results Skin and muscle exposed to 3 hours of ischemia showed significantly higher rejection scores than after 1 hour of ischemia, as evidenced by a more aggressive diffuse lymphocytic infiltration with disruption of tissue architecture. The rejection score in skin with 3-hour ischemia was 5.0 ± 0.1 versus 3.7 ± 0.2 with 1-hour (Mann-Whitney U test; P < .05). The rejection score in muscle exposed to 3-hour ischemia was 3.6 ± 0.3 versus 2.5 ± 0.1 with 1-hour ( P < .05). Conclusions Muscle and skin demonstrated increased acute rejection of allotransplants with increased subcritical ischemic time. This study supports the use of aggressive methods to reduce subcritical ischemic injury during allotransplantation of composite tissue and inclusion of muscle in postoperative biopsies in this early investigational period of CTA.

D010 Mesenchymal stem cells protect cardiomyocytes from reperfusion injury through a paracrine activation of the PI3 kinase pathway

Previous data suggest that implantation of mesenchymal stem cells (MSCs) improves heart function after myocardial infarction. We investigated whether protection afforded by MSCs might involve a paracrine activation of the PI3 kinase pathway in reperfused cardiomyocytes. MSCs and neonatal rat cardiomyocytes (NRCs) were isolated and cultured separately. NRCs (2.106) were subjected to 5 hours of ischemia followed by 16 hours of reperfusion. At the time of reperfusion, NRCs (n=8-14/group) received either fresh medium (control group), or the following treatments: MSCs (2.105 MSCs in fresh medium), conditioned SN (MSCs supernatant alone (i.e. without MSCs) obtained after 8 hours of serum deprived culture), [conditioned SN + LY294002] (15 microM of LY294002 a specifi c inhibitor of PI3K), [conditioned SN + Wortmannin] (100 nM of wortmannin, a non specifi c inhibitor of PI3K), or CsA (200 nM in fresh medium) a potent inhibitor of the mitochondrial permeability transition pore. Cell death was assessed by LDH release in NRCs supernatant at the end of reperfusion. As expected, LDH activity was dramatically reduced by CsA, averaging 4 % of control values. LDH activity was signifi cantly reduced by MSCs alone and by conditioned SN, averaging 29 % and 12 % of control value, respectively. Both LY294002 and wortmannin signifi cantly attenuated conditioned SN induced protection. our data suggest that MSCs can protect NRCs from reperfusion injury through a paracrine activation of the PI3K pathway.

Proteasome Inhibition Promotes Functional Recovery After Peripheral Nerve Reperfusion Injury

The proteasome degrades NF-kappaB blocking protein (I-kappaB) and activates NF-kappaB that plays as a key transcriptional factor to regulate inflammatory factors that are involved in the tissue reperfusion injury. This study was designed to assess whether the proteasome inhibitor can attenuate peripheral nerve ischemia/reperfusion (I/R) injury and consequently promote motor functional recovery after ischemic insult. Rat sciatic nerves were exposed to 2 hour of ischemia followed by various periods of reperfusion. Rats were administered either proteasome inhibitor (bortezomib) or phosphate-buffered saline 30 minutes before reperfusion start. Results were evaluated using a walking track test, and an isolated muscle contraction test, and by muscle weight, and histology. Bortezomib treatment induced an earlier improvement in sciatic functional index and a more rapid restoration of contractile force and wet weight of extensor digitorum longus muscle. Bortezomib reduced early axonal degeneration and promoted regeneration. This study indicates that bortezomib; a proteasome inhibitor, is effective at promoting the functional recovery of reperfused peripheral nerve. The proteasome inhibition may play a role as one of the clinical strategy in the peripheral nervous system I/R injury with further understanding its mechanism of action.

Utilização da glutamina no tratamento de lesões de isquemia e reperfusão no jejuno em eqüinos

Sob anestesia geral e com controle da pressão arterial, 12 eqüinos foram submetidos simultaneamente a modelos de isquemia venosa e distensão intraluminal em segmentos do jejuno por 2 h, seguidos de 12 h de reperfusão. Seis eqüinos foram tratados com glutamina a 2% (50mg/kg) por via intravenosa e seis com solução fisiológica em igual volume, 1 h após o início da isquemia e às 6h de reperfusão. Foram colhidas amostras de tecido intestinal antes e com 2 h de isquemia e com 2 e 12 h de reperfusão para avaliações histopatológica e ultraestrutural, mensuração da área e número das vilosidades por mm² e atividade de mieloperoxidade (MPO). Não foram encontradas diferenças entre os grupos controle e tratado. Concluiu-se que a glutamina, nas condições deste trabalho, não atenua lesões de isquemia e reperfusão intestinal em eqüinos.

Management of traumatic brachial artery injuries: A report on 49 patients

BACKGROUND AND OBJECTIVE:The brachial artery is the most frequently injured artery in the upper extremity due to its vulnerability. The purpose of our study was to review our experience with brachial artery injuries over a 9-year period, describing the type of injury, surgical procedures, complications, and associated injuries.PATIENTS AND METHODS:Forty-nine patients with brachial artery injury underwent surgical repair procedures at our hospital, from the beginning of May 1999 to the end of June 2008. The brachial artery injuries were diagnosed by physical examination and Doppler ultrasonography. Depending on the mode of presentation, patients were either taken immediately to the operating room for bleeding control and vascular repair or were assessed by preoperative duplex ultrasonography.RESULTS:This study group consisted of 43 males and 6 females, ranging in age from 6 to 65 years with a mean (SD) age of 27.9 (6.7) years. The mechanism of trauma was penetrating in 45 patients and blunt in the remaining 4 patients. Stab injury was the most frequent form of penetrating trauma (24 of 45). Treatment included primary arterial repair in 5 cases, end-to-end anastomosis in 28 cases, interposition vein graft in 15 cases, and interposition-ringed polytetrafluoroethylene graft in 1 case. Associated injuries were common and included venous injury (14), bone fracture (5), and peripheral nerve injury (11). Fifteen patients developed postoperative complications. One patient underwent an above-elbow amputation.CONCLUSIONS:Prompt and appropriate management of the brachial artery injuries, attention to associated injuries, and a readiness to revise the vascular repair early in the event of failure will maximize patient survival and upper extremity salvage.

Ischemia-reperfusion Injury in the Lung: Quantitation Using Electron Microscopy

The primary objectives of this study were to determine the time course of ischemia-reperfusion injury in an isolated rabbit lung model and to quantify this damage using electron microscopic methodology coupled with statistical analyses. Eight groups of isolated rabbit lungs (n = 5 per group) were subjected to predetermined periods of ischemia-reperfusion. Two hours of ischemia and 4 hours of reperfusion were concluded to be necessary to induce optimal ischemia-reperfusion injury in this model. Four other groups were subjected to 2 hours of ischemia followed by selected periods of reperfusion. These groups were compared to 4 control groups that were perfused for comparable time periods but without the initial ischemia. New quantitative methods were developed based on the average surface area of the alveoli and average number of alveoli per unit surface area, using scanning electron microscopic examination. Ischemia per se caused substantial damage. Restoration of volume and nutrients reversed this damage at 1 hour of reperfusion, but severe damage was evident at 4 hours of reperfusion, as reported by subjective and blinded examination. By using the new quantitative methods, there was a significant difference between the groups (P < .005) according to the time of post-ischemia-reperfusion, which correlated with the subjective evaluation of damage. These 2 new quantitative techniques provide an objective assessment of damage in the isolated rabbit lung model, suggesting that they warrant further consideration in similar studies of ischemia reperfusion injury.

Ischemia-Reperfusion–Induced Apoptotic Endothelial Cells Isolated from Rat Skeletal Muscle

The purpose of the present study was to investigate ischemia-reperfusion-induced apoptosis and necrosis in endothelial cells isolated from skeletal muscle. A vascular pedicle isolated rat gracilis muscle model was used. After surgical preparation, clamps were applied to the vascular pedicle to create 4 hours of ischemia and released for reperfusion (ischemia-reperfusion group, n = 9). Clamping was omitted in sham ischemia-reperfusion rats (sham ischemia-reperfusion group, n = 9). The muscle samples were harvested after 20 hours of reperfusion for the process of cell isolation. One hundred thousand cells from each sample were stained by monoclonal anti-CD146-fluorescein (a principal marker for mature endothelial cells), Annexin V-PE, or 7-aminoactinomycin D to detect and quantify apoptotic and necrotic cells. Twenty thousand cells from each sample were scanned and analyzed by flow cytometry. The average +/- SEM of CD146-fluorescein-positive cells was 20.0 +/- 2.9 percent, suggesting that these cells might be endothelial cells from the muscle microvasculature. In the population of gated CD146-fluorescein-positive cells, the average percentage of apoptotic cells (stained by Annexin V-PE) was 15.9 +/- 2.2 percent in the sham ischemia-reperfusion group and 33.5 +/- 5.3 percent in the ischemia-reperfusion group (p < 0.01), the average percentage of necrotic/apoptotic cells (stained by both 7-aminoactinomycin D and Annexin V-PE) was 17.8 +/- 4.1 percent in the sham ischemia-reperfusion group and 39.2 +/- 3.1 percent in the ischemia-reperfusion group (p < 0.01). Given the results of the present study, the authors hypothesize that the endothelial cells lining microscopic blood vessels are among the major contributors to ischemia-reperfusion-induced cell apoptosis and necrosis detected from rat skeletal muscle.