Poly adenosine diphosphate-ribose polymerase inhibitor PJ34 abolishes systemic proinflammatory responses to thoracic aortic ischemia and reperfusion

BACKGROUND: Systemic inflammatory responses contribute to mortality after thoracoabdominal aneurysm repair. Poly adenosine diphosphate (ADP) ribose polymerase (PARP) activity is known to modulate inflammation in animal models of injury. The effect of the PARP inhibitor PJ34 and genetic deletion of PARP-1(PARP -/-) on the systemic inflammatory response after thoracic aortic ischemia reperfusion (TAR) is not known. STUDY DESIGN: In one group, all mice were subject to TAR followed by 48 hours of reperfusion. Treated mice (PJ, n=24) were given PJ34 IP; untreated mice (UN, n=41) received normal saline intraperitoneally. The number of mice in each group was selected to have a similar number of survivors by 48 hours. In a second group, sham animals were subjected to mediastinotomy alone (sham, n=10) without TAR, and were compared with mice with deletion of the PARP-1 isoform (PARP-1 -/-, n=11) subjected to TAR. Tissue extracts were assayed for keratinocyte derived chemokine and granulocyte colony stimulating factor. Serum was assayed for interleukin-6. RESULTS: PJ34 treatment decreased mortality throughout the experimental protocol. There were no mortalities in the sham operated mice or PARP -/- mice subjected to TAR. PJ34 treatment decreased serum levels of interleukin-6 (p=0.01) and hepatic levels of interleukin-6 mRNA when compared with untreated and PARP-/- mice (p < 0.01). Only liver and kidney cytokine levels were decreased by PJ34 treatment (p < 0.05). In PARP-/- mice subjected to TAR, tissue cytokine levels were not different from those in sham mice. CONCLUSIONS: PARP inhibition may represent a novel therapeutic approach to minimizing inflammatory sequelae after TAR.     

PJ34, a poly-ADP-ribose polymerase inhibitor, modulates visceral mitochondrial activity and CD14 expression following thoracic aortic ischemia-reperfusion

Background

Visceral ischemia-reperfusion injury (VI) contributes to adverse outcomes following the repair of thoracoabdominal aneurysms. Experiments were designed to determine whether a poly-adenosine diphosphate-ribose polymerase (PARP) inhibitor modulates indexes of metabolic function (mitochondrial activity), inflammatory cell activation, and tissue inflammation (lipopolysaccharide receptor CD14 messenger ribonucleic acid) following VI.

Methods

129S1/SvImj mice were subjected to thoracic aortic occlusion followed by 48 hours of reperfusion. Normal saline was administered to 25 untreated control mice and PJ34 to 21 mice before and immediately after thoracic aortic ischemia-reperfusion. Sham mice (n = 13) underwent median sternotomy alone. At 48 hours, all animals were euthanized and tissues harvested for quantitative analysis.

Results

PJ34 improved intestinal (P < .05) but not hepatic mitochondrial activity following reperfusion. CD14 messenger ribonucleic acid levels in liver (P < .004), kidney (P < .003), and spinal cord (P < .03) tissue were less in PJ34-treated mice.

Conclusions

PJ34 preserved the metabolic function of intestinal but not hepatic tissue during reperfusion. PJ34 uniformly decreased the expression of an important marker of inflammatory cell activation and tissue inflammation in visceral tissue following VI. PARP inhibitors may serve as a therapeutic modality to abrogate the stress response to VI.     

Local administration of the Poly ADP-Ribose Polymerase (PARP) inhibitor, PJ34 during hindlimb ischemia modulates skeletal muscle reperfusion injury

BACKGROUND: PARP stabilizes DNA and modulates inflammation in murine models of sepsis, stroke, and myocardial infarction. Previous studies have shown that systemic PARP inhibition before hindlimb ischemia preserves tissue viability and modulates cytokine synthesis during reperfusion. The purpose of this study was to determine whether intra-muscular (IM) administration of PJ34, a potent inhibitor of PARP, after the onset of acute hindlimb ischemia (post hoc) modulates the local production of inflammatory mediators during ischemia/reperfusion (I/R). MATERIALS AND METHODS: The control tension tourniquet was used to establish unilateral hindlimb ischemia in mice for 3 h followed by 48 h I/R. The treatment group (PJ) received IM PJ34 (10 mg/kg) in the affected hindlimb 90 min into ischemia whereas the control group (UN) received IM saline (150 uL) at the same time point. Skeletal muscle viability (MTT mitochondrial activity), local neutrophil chemoattractant protein (KC), Interleukin 6 (IL-6), Interleukin 1beta (IL-1beta), and Myeloperoxidase (MPO) levels were measured in protein extracts after the reperfusion period. RESULTS: Muscle viability (102% +/- 10 PJ, 78% +/- 4 UN, P = 0.04), IL-B (21.1 +/- 1.3 PJ, 15.5 +/- 1.0 UN, P = 0.02), and IL-6 levels (16.3 +/- 1.2 PJ, 10.9 +/- 1.4 UN, P = 0.04) after 48 I/R were significantly higher in PJ. KC and MPO levels were higher in PJ but neither reached statistical significance. CONCLUSIONS: Post hoc PJ34 therapy appears to protect skeletal muscle from I/R injury despite increased levels of local cytokines. These initial findings support the role of local post hoc therapy in the treatment of acute limb threatening ischemia suggesting that further study of this novel therapy is warranted.     

Poly(adenosine diphosphate ribose) polymerase inhibition modulates spinal cord dysfunction after thoracoabdominal aortic ischemia-reperfusion

OBJECTIVE: Spinal cord injury (SCI) remains a source of morbidity after thoracoabdominal aortic reconstruction. These studies were designed to determine whether PJ34, a novel ultrapotent inhibitor of the nuclear enzyme poly(adenosine diphosphate ribose) polymerase (PARP) could modulate neurologic injury after thoracic aortic ischemia reperfusion (TAR) in a murine model of SCI. METHODS: Forty-one anesthetized male mice were subject to thoracic aortic occlusion (11 minutes) through a cervical mediastinotomy followed by 48 hours of reperfusion (TAR) under normothermic conditions. PJ34-treated mice (PJ, n = 12) were given 10 mg/kg PJ34 intraperitoneally 1 hour before ischemia and 1 hour after unclamping. The control group (UN, n = 21) received normal saline intraperitoneally 1 hour before ischemia and 1 hour after unclamping. Sham animals (n = 10) were subject to thoracic aortic exposure with no aortic clamping and similar intraperitoneal normal saline injections. PARP-1-/- (KO, n = 8) mice were subjected to the same conditions as the UN mice. Blinded observers rated murine neurologic status after TAR by using an established rodent paralysis scoring system. Murine spinal cords were subjected to cytokine (GRO-1) protein analysis as a marker of inflammation and immunohistochemical analysis (hematoxylin-eosin and PAR staining). Paralysis scores (PS) and GRO-1 levels were compared with analysis of variance, and survival data were compared with chi 2 . RESULTS: Immediately after TAR, UN and PJ mice had severe neurologic dysfunction (PS = 5.8 +/- 0.1 and 4.6 +/- 0.6, respectively; P > .05), which was significantly worse than the KO mice (PS = 1.0 +/- 0.7, P < .001). After 6, 24, and 48 hours KO mice had no discernable neurologic injury (PS = 0). Six hours after TAR, PJ mice significantly improved (PS = 1.1 +/- 0.73, P < .001) and remained improved at 24 (PS = 0.7 +/- 0.6) and 48 hours (PS = 0.6 +/- 0.6). UN mice did not improve their PS, and Sham mice showed no neurologic abnormality at any time during these experiments. The mortality at 48 hours was 0% for PJ and KO mice, 43% for UN (P = .012), and 0% for Sham. GRO-1 levels were significantly decreased in PJ and KO versus UN mice (UN, 583 +/- 119 vs PJ, 5.8 +/- 0 vs KO, 5.3 +/- 1.4 mg/pg; P < .0001). Immunohistochemistry showed evidence of decreased PAR staining and ventral motor neuron injury in PJ mice. CONCLUSIONS: Genetic deletion of PARP or inhibition of its activity (PJ34) rescued neurologic function in mice subjected to TAR. PARP inhibition might represent a novel therapeutic approach for prevention of SCI after TAR.     

Poly (ADP-ribose) polymerase inhibition prevents spontaneous and recurrent autoimmune diabetes in NOD mice by inducing apoptosis of islet-infiltrating leukocytes

Poly (ADP-ribose) polymerase (PARP) is a nuclear enzyme that consumes NAD in response to DNA strand breaks. The PARP inhibitor nicotinamide prevents NAD consumption and protects islet beta-cells from chemically induced necrosis but not cytokine-induced apoptosis. Therefore, it is unclear how nicotinamide protects NOD mice from autoimmune diabetes in which apoptosis is the mode of beta-cell death. To investigate the mechanism of diabetes prevention by PARP inhibition, we studied the effects of a novel, potent PARP inhibitor, PJ34, a phenanthridinone derivative, on diabetes development in NOD mice and on diabetes recurrence in diabetic NOD mice transplanted with syngeneic islets. PJ34 administration from age 5 or 15 weeks significantly decreased insulitis, beta-cell destruction and diabetes incidence, and protection from diabetes continued for 12 weeks after PJ34 therapy was stopped. Similarly, syngeneic islet graft survival was prolonged and outlasted therapy in PJ34-treated mice. Immunohistochemical studies revealed significantly fewer leukocytes in islet grafts of PJ34-treated mice, together with increased apoptosis of these cells and decreased expression of the T helper 1-type cytokine interferon (IFN)-gamma. These results suggest that PARP inhibition protects against autoimmune beta-cell destruction in NOD mice by inducing apoptosis of islet-infiltrating leukocytes and decreasing IFN-gamma expression in the islets.     

Enoxaparin does not ameliorate limb ischemia-reperfusion injury

OBJECTIVE: Since low molecular weight heparin has greater bioavailability and sustained serum levels in vivo than unfractionated heparin, it has been used to supplant unfractionated heparin to achieve therapeutic anticoagulation in humans. These studies were designed to determine whether treatment with enoxaparin could protect murine skeletal muscle from ischemia reperfusion injury. METHODS: C57BL6 mice were divided into four groups. Sham control animals underwent 90 min of anesthesia alone. All other groups underwent 90 min of unilateral hindlimb ischemia. At the onset of reperfusion, animals received either normal saline (control and saline) or 4 mg/kg of enoxaparin subcutaneously twice daily. Groups were followed for 24 or 48 h reperfusion. Hindlimb skeletal muscle blood flow was measured by laser Doppler, and muscle was removed for histological and protein analysis. Tissue thrombosis was evaluated by thrombin antithrombin III (TAT III), local inflammation by measurement of proinflammatory cytokines (macrophage inflammatory protein-2: MIP-2, monocyte chemoattractant protein-1: MCP-1), and neutrophil infiltration by myeloperoxidase (MPO) using enzyme-linked immunosorbent assay. Plasma levels of Factor Xa were measured during reperfusion to confirm therapeutic levels of anticoagulation. Comparisons were calculated using analysis of variance. RESULTS: At 24 h reperfusion, there was increased expression of MIP-2, MCP-1, MPO, and TAT III in saline and enoxaparin treated mice compared with control (*P < 0.05). By 48 h reperfusion, all parameters measured remained greater than control except for the enoxaparin treated mice whose TAT III levels were significantly less than untreated mice (P < 0.05). Despite documented therapeutic anticoagulation and decreased levels of markers of thrombosis in enoxaparin treated mice, there was no difference in tissue cytokines, inflammatory markers, degree of muscle fiber injury (31% +/- 8% versus 30% +/- 5%) or muscle flow between ischemia-reperfusion groups (2447 +/- 141 versus 2475 +/- 74 flux units) at 48 h reperfusion. CONCLUSIONS: Post hoc administration of enoxaparin did not affect local tissue thrombosis, inflammatory markers, or muscle necrosis. This suggests that despite its potent in vivo activity, enoxaparin did not modulate skeletal muscle injury, thrombosis, or inflammatory following ischemia reperfusion. enoxaparin may not be useful in mediating skeletal muscle injury when administered in a clinically relevant scenario.     

Reduced ischemia-reperfusion injury in muscle Experiments in rats with EPC-K1, a new radical scavenger

L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1 -benzopyran-6-yl hydrogen phosphate] potassium salt (EPC-K1), a phosphate diester of alpha-tocopherol and ascorbic acid, is a potent antioxidant. We examined the effects of EPC-K1 on ischemia-reperfusion injury in the skeletal muscle of rats, using an ischemic revas-cularized hind limb model. Warm ischemia (25 C), produced by vascular pedicle clamping, was sustained for 4 hours. After 24 hours of reperfusion, skeletal muscle injury was evaluated in 2 groups: one group treated by intravenous injection of EPC-K1 (10 mg/kg) prior to ischemia, and a group of controls. The EPC-K1 -treated group showed a statistically significant amelioration in the reduction of the isometric muscle contraction, inhibition of the elevation of the muscle wet- to dry-weight ratio, limitation of the muscle level of thiobarbituric acid reactive substances and the serum levels of creatine phos-phokinase, lactate dehydrogenase and mitochondrial glutamic oxaloacetic transaminase, and reduction of the extent of muscle injury according to the histological findings. These observations indicate that EPC-K1 acted effectively on ischemia-reperfusion injury in the rat skeletal muscle and thereby improved muscle function.     

Inhalation of carbon monoxide reduces skeletal muscle injury after hind limb ischemia-reperfusion injury in mice

BackgroundThe purpose of this study was to determine if inhaled carbon monoxide (CO) can ameliorate skeletal muscle injury, modulate endogenous heme oxygenase-1 expression, and improve indexes of tissue integrity and inflammation after hind limb ischemia reperfusion.MethodsC57BL6 mice inhaling CO (250 ppm) or room air were subjected to 1.5 hours of ischemia followed by limb reperfusion for either 3 or 6 hours (total treatment time, 4.5 or 7.5 h). After the initial period of reperfusion, all mice breathed only room air until 24 hours after the onset of ischemia. Mice were killed at either the end of CO treatment or at 24 hours' reperfusion. Skeletal muscle was subjected to histologic and biochemical analysis.ResultsCO treatment for 7.5 hours protected skeletal muscle from histologic and structural evidence of skeletal muscle injury. Serum and tissue cytokines were reduced significantly (P < .05) in mice treated with CO for 7.5 hours. Tubulin, heme oxygenase, and adenosine triphosphate levels were higher in CO-treated mice.ConclusionsInhaled CO protected muscle from structural injury and energy depletion after ischemia reperfusion.     

肢体缺血再灌注损伤的新型动物模型制作

[目的]用充气止血带制作肢体缺血再灌注损伤的新型动物模型,研究其对周围神经和骨骼肌损伤的影响.[方法]选择健康新西兰大白兔6个月龄,30只,体重(3.5 ±0.3) kg,雌雄不限,在家兔左侧后肢环扎充气止血带,于不同时间点松开,造成左侧后肢缺血再灌注损伤的模型.随机分为3组,每组10只.A组:对照组,B组:缺血2h,C组:缺血4h.对照组不扎充气止血带,第1、2、3、4、5、6h检测肢体的神经电生理学指标,B组、C组于再灌注(松开止血带,血供恢复后)的1、2、3、4、5、6h检测肢体的神经电生理学指标,A组于第6h观察骨骼肌的形态,B、C组于再灌注(松开止血带,血供恢复后)的第6h观察骨骼肌的形态,每组于术后第5d评估左侧后肢的行走功能.[结果]随着缺血后再灌注时间的延长,B、C和A组相比较,周围神经的潜伏期延长、波幅降低,传导速度降低,三组之间的潜伏期、波幅、传导速度差异均有统计学意义(P＜0.05),光镜观察骨骼肌可见(B、C组):横纹紊乱、肌纤维断裂、间质血管扩张充血、大量中性粒细胞浸润.[结论]经过缺血期和再灌注损伤的交互作用后,肢体的功能性损伤进一步加重,出现了不可逆的病损.该模型制作对动物的损伤较小,更贴近临床.     

Myocardial protection by PJ34, a novel potent poly (ADP-ribose) synthetase inhibitor

BACKGROUND: The activation of poly (ADP-ribose) synthetase plays an important role in the pathogenesis leading to myocardial ischemia-reperfusion injury. The aim of this study was to determine if a novel potent inhibitor of poly (ADP-ribose) synthetase, PJ34, provides myocardial protection. METHODS: Pigs were subjected to 60 minutes of regional ischemia followed by 180 minutes of reperfusion. Ten mg/kg of PJ34 (PJ34; n = 6) was administrated intravenously (treated group) from 15 to 5 minutes before reperfusion followed by 3 mg/kg/hour of PJ34 from 5 minutes before reperfusion to the end of 180 minutes reperfusion. Control pigs (n = 7) received vehicle only. Arterial and left ventricular pressure and coronary flow were monitored. RESULTS: The PJ34 showed significant reduction on infarct size (37.5%+/-4.5% and 50.5%+/-4.8% of the area at risk) for PJ34 and control pigs groups, respectively, (p < 0.05). Significant reduction in postsystolic shortening, as well as improvement on segment shortening, and positive first derivative of pressure over time (+dP/dt) maximum were also observed in PJ34 versus control pigs (p < 0.05). CONCLUSIONS: Our results suggest that PJ34 provides cardioprotection by decreasing myocardial infarct size and enhancing postischemic regional and global functional recovery.     

Mitochondrial transplantation ameliorates acute limb ischemia

ObjectiveAcute limb ischemia (ALI), the most challenging form of ischemia-reperfusion injury (IRI) in skeletal muscle tissue, leads to decreased skeletal muscle viability and limb function. Mitochondrial injury has been shown to play a key role in skeletal muscle IRI. In previous studies, we have demonstrated that mitochondrial transplantation (MT) is an efficacious therapeutic strategy to replace or to augment mitochondria damaged by IRI, allowing enhanced muscle viability and function in cardiac tissue. In this study, we investigated the efficacy of MT in a murine ALI model.MethodsC57BL/6J mice (male, 10-12 weeks) were used in a model of ALI. Ischemia was induced by applying a tourniquet on the left hindlimb. After 2 hours of ischemia, the tourniquet was released, and reperfusion of the hindlimb was re-established; either vehicle alone (n = 15) or vehicle containing mitochondria (n = 33) was injected directly into all the muscles of the hindlimb. Mitochondria were delivered at concentrations of 1 × 10⁶ to 1 × 10⁹ per gram wet weight to each muscle, and the animals were allowed to recover. Sham mice received no ischemia or injections but were anesthetized for 2 hours and allowed to recover. After 24 hours of recovery, limb function was assessed by DigiGait (Mouse Specifics Inc, Boston, Mass), and animals were euthanized; the gastrocnemius, soleus, and vastus medialis muscles were collected for analysis.ResultsAfter 24 hours of hindlimb reperfusion, infarct size (percentage of total mass) and apoptosis were significantly decreased (P < .001, each) in the gastrocnemius, soleus, and vastus medialis muscles in MT mice compared with vehicle mice for all mitochondrial concentrations (1 × 10⁶ to 1 × 10⁹ per gram wet weight). DigiGait analysis at 24 hours of reperfusion showed that percentage shared stance time was significantly increased (P < .001) and stance factor was significantly decreased (P = .001) in vehicle compared with MT and sham mice. No significant differences in percentage shared stance time (P = .160) or stance factor (P = .545) were observed between MT and sham mice.ConclusionsMT ameliorates skeletal muscle injury and enhances hindlimb function in the murine model of ALI.     

Recombinant human manganese superoxide dismutase attenuates early but not delayed skeletal muscle dysfunction following reperfusion injury.

OBJECTIVES: to assess the efficacy of recombinant human manganese superoxide dismutase (rhMnSOD) in prevention of early and late skeletal muscle ischaemia-reperfusion injury mediated by superoxide (O2-). Design : randomised controlled trial. MATERIALS: seventy-two Sprague-Dawley rats (250-350 g) randomised to receive either 7.5 mg/kg of rhMnSOD or saline. Four hours of ischaemia was induced in the cremaster muscle by dissecting free and clamping its vascular supply. Cremaster muscle contractile function was assessed following 90 minutes, 24, 48 hours and one week of reperfusion. Electrophysiological muscle function was assessed using electrical field stimulation in an organ bath system. RESULTS: muscle function in the untreated groups following ischaemia reperfusion was significantly reduced at 90 minutes, 24, 48 hours and one week of reperfusion (p <0.05). rhMnSOD significantly protected and maintained normal muscle function at 24 and 48 hours (p <0.001). However at one week of reperfusion there was a reduction in function of the treated muscle, such that there was no significant difference between treated and untreated muscle at this point in time. CONCLUSIONS: these data demonstrate that skeletal muscle dysfunction after ischaemia reperfusion injury is attenuated at 24 and 48 hrs of reperfusion by the superoxide scavenger rhMnSOD. This protective effect is not maintained after seven days of reperfusion.     

Permeability changes following ischemia-reperfusion injury in the rabbit hindlimb.

Changes in permeability following ischemia-reperfusion injury were assessed in the intact rabbit hindlimb by measuring the transvascular clearance of 125I-labeled rabbit serum albumin. Ischemia was induced for periods of 1 or 2 hours by use of a pneumatic tourniquet inflated to 300 mmHg. Following ischemia, the limb was reperfused for 1, 2, or 3 hours. The albumin clearance in the gastrocnemius muscle of control rabbits was 5.1 +/- 0.7 (mean +/- SEM) microliters/hr/g dry weight. Following 1 hour of ischemia and reperfusion, muscle albumin clearance rose to 71.4 +/- 26 microliters/hr/g dry weight which was not significantly different from those animals that underwent 2 hours of ischemia. Muscle albumin clearance continued to be elevated following 2 hours of reperfusion; however, it returned toward control levels after 3 hours of reperfusion. These data suggest there is a transient increase in albumin permeability following ischemia-reperfusion injury in skeletal muscle.     

Role of poly(ADP-ribose) polymerase activation in the pathogenesis of cardiopulmonary dysfunction in a canine model of cardiopulmonary bypass.

OBJECTIVE: To investigate the effects of PARP inhibition on cardiac and pulmonary function during reperfusion in a clinically relevant experimental model of cardiopulmonary bypass. METHODS: Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 min of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6), or the potent PARP-inhibitor PJ34 (5 mg/kg; n = 6). Biventricular hemodynamic variables were measured by combined pressure-volume-conductance catheters. Coronary and pulmonary blood flow, vasodilator responses to acetylcholine and sodium-nitroprusside and pulmonary function were also determined. The cardiac and pulmonary activation of PARP was detected by poly(ADP-ribose) immunohistochemistry. RESULTS: Administration of PJ34 led to a significantly better recovery of left and right ventricular systolic function (P < 0.05) after 60 min of reperfusion. Coronary blood flow was also significantly higher in the PJ34 treated group (P < 0.05) PJ34 treatment preserved the acetylcholine-induced increases in coronary and pulmonary blood (P < 0.05) Pulmonary function in terms of alveolar arterial oxygen difference was better maintained in the PJ34 treated animals (P < 0.05). Immunohistochemical staining revealed PARP activation after cardiopulmonary bypass in both the heart and lung, which was prevented by PJ34. CONCLUSIONS: PARP inhibition improves the recovery of myocardial and endothelial function after hypothermic cardiac arrest and protects against the development of remote pulmonary injury during cardiopulmonary bypass.     

Correlation of morphological findings with functional reserve in the aging donor: role of the poly (ADP-ribose) polymerase

INTRODUCTION: The enzyme poly (ADP-ribose) polymerase (PARP-1) participates in the first events of DNA repair in higher organisms. Under conditions of tissue ischemia, this action can lead to significant decreases in NAD(+), massive adenosine triphosphate (ATP) depletion, and cell death. In renal grafts with pretransplantation cold ischemia and subsequent ischemia-reperfusion injury, overactivation of PARP-1 may lead to a higher index of acute tubular necrosis, a delay in total recovery of the function of the transplanted organ, and an early progression to chronic graft nephropathy. The present study examined whether increased tubular expression of PARP-1 in kidneys from aged donors contributed to recipient renal function. MATERIAL AND METHOD: We studied the nuclear expression of PARP-1 using immunohistochemistry with monoclonal antibody PAR01 in 75 kidney biopsy specimens from 40 aged donors. RESULTS: Immunohistochemical expression of PARP-1 showed a statistically significant relationship with donor age (r =.408, P =.006, Spearman test), with time required to achieve effective diuresis (r =.386, P =.01, Spearman test) and with creatinine levels in the first 3 months. We also highlighted a greater intensity of PARP-1 expression in suboptimal donor kidneys that failed to reduce the serum creatinine levels to <1.7 mg/dL (creatinine <1.7 PARP: 1.29 +/- 1.49 vs creatinine >1.7 PARP: 2.29 +/- 1.33, P =.047, Mann-Whitney U test). CONCLUSION: We conclude that the determination of PARP-1 in biopsy specimens from aged donors may be a useful predictive factor for renal graft function.     

CXC chemokine expression and synthesis in skeletal muscle during ischemia/reperfusion

BACKGROUND: The chemokines keratinocyte-Derived Cytokine (KC) and macrophage inflammatory protein (MIP)-2, murine equivalents of human interleukin 8, have been implicated in remote injury after acute hind limb ischemia/reperfusion (I/R). These studies were designed to determine whether the cytokines responsible for remote tissue injury are also synthesized and accumulate in the ischemic or reperfused hind limb. METHODS: B6, 129SF2/J mice were subjected to either 3 hours of unilateral hind limb ischemia alone (IA) or 3 hours of ischemia followed by 4 or 24 hours of reperfusion (I/R). After IA or I/R, experimental and control (nonischemic) contralateral hind limbs were harvested for analysis of protein content, messenger RNA (mRNA), tissue edema, and viability. RESULTS: IA did not increase KC or MIP-2 mRNA or protein levels. In contrast, I/R resulted in a 15- and 10-fold increase in KC mRNA after 4 and 24 hours of reperfusion, respectively. KC protein levels were increased 10-fold after 4 hours of reperfusion and 30-fold after 24 hours (vs IA or sham; P < .001). MIP-2 mRNA transiently increased 42-fold after 4 hours of reperfusion but decreased to basal levels after 24 hours of reperfusion. Despite the relative increase in MIP-2 mRNA by 4 hours of reperfusion, significantly increased (8- to 10 fold) MIP-2 protein levels were not detected until 24 hours of reperfusion only in the reperfused limbs. Tissue edema was increased significantly (P < .01) compared with sham after just 4 hours of reperfusion and remained increased at 24 hours. Tissue viability decreased 52% after 4 hours of reperfusion and did not change significantly by 24 hours. CONCLUSIONS: Skeletal muscle is a site of significant ongoing chemokine synthesis during reperfusion. The persistent increase in muscle chemokine levels at 24 hours of reperfusion was not associated with increased edema or injury. The role of these chemokines during reperfusion may be further investigated by local or oral administration of chemokines or chemokine receptor antagonists. CLINICAL RELEVANCE: I/R injury remains an important clinical problem across a variety of surgical specialties. In the critical care arena, serum levels of proinflammatory cytokines have been useful in predicting the mortality associated with acute respiratory distress syndrome and sepsis. In this article, the data presented indicate that murine skeletal muscle produces potent proinflammatory neutrophil and macrophage chemokines during reperfusion, but not during ischemia. These findings suggest that measurement of tissue and/or serum levels of chemokines during reperfusion may be an important adjunct to predicting tissue injury along with ongoing inflammation during the clinical course of reperfusion injury. Within the vascular system, severe inflammatory responses are usually associated with thrombotic events. New techniques to noninvasively image thrombin activation (by using magnetic resonance imaging) in reperfused limbs may coincide with the pattern of murine skeletal muscle chemokine expression in humans. The data suggest that reperfusion is when chemokine mRNA and protein synthesis increase. Within the time periods studied in these experiments, the chemokine component of the inflammatory response remained in the reperfused, rather than the systemic nonreperfused, tissue. This observation may underestimate the degree of the systemic response to ischemia because the single mouse hind limb represents only 7% of the mouse total body area, whereas the human limb represents nearly 18% of the adult body area. Despite this shortcoming, these data provide potential temporal and quantitative information regarding the location and magnitude of chemokine synthesis in skeletal muscle during reperfusion.     

运动终板在骨骼肌缺血再灌注损伤中的病理变化

目的 探讨骨骼肌缺血再灌注（ischemia—reperfusion，IR）过程中运动终板（neuromuscular junction，NMJ）损伤的病理改变进程。方法 将Wistar大鼠48只制备仅神经血管蒂及两端腱性相连的腓肠肌内侧头肌瓣模型。分为6组（n=8），A组：正常对照组，不经缺血处理取材；B组：肌肉缺血3h取材；C组：缺血4．5h取材；D组：缺血4．5h，通血1．5h取材；E组：缺血4．5h，通血24h取材；F组：缺血4．5h，通血2周取材。观察肌肉大体变化及肌肉标本行氯化金压染后NMJ的形态学变化，标本经乙酰胆碱酯酶（acetylcholinesterase，AChE）及结合琥珀酸脱氢酶（succinate dehydrogenase，SDH）染色后行半定量分析。另取5只大鼠分别制成如A、C、E组模型，取材后标本分别行HE染色、氯化金（AuCl3）染色连续切片等辅助实验。结果 肌肉大体观察：B组肌肉呈紫色、肿胀；C组呈紫黑色、肿胀加重、无弹性和收缩反应并有较多暗红色血性渗出；D组较C组颜色浅，肿胀减轻，弹性差，无收缩，质脆硬，渗出少且清亮；E组与D组相似、渗出更少；F组呈红灰相间，并有黄色坏死组织外露，肌肉挛缩、无收缩及弹性，与周围广泛粘连。氯化金染色：缺血和再灌注期肌纤维坏死发生最早，随后是坏死肌纤维上NMJ的溃变，最后神经纤维也发生崩解，如同树叶凋落。AChE结合SDH染色：B、C组的AChE含量与A组比较差异无统计学意义（P〉0．05）；D、E、F各组AChE及SDH的含量均急剧下降，各组AChE含量与A、C组比较差异有统计学意义（P〈0．01）。结论 肌肉内神经纤维至NMJ的分布极象树状结构。缺血期NMJ比肌纤维更能耐受缺血损伤，NMJ的存在依赖于肌纤维的存活。应对坏死肌肉实施进一步清创，IR损伤才可得到有效控制。     

Early tumor necrosis factor-alpha release from the pulmonary macrophage in lung ischemia-reperfusion injury

OBJECTIVE: Tumor necrosis factor-alpha is a proinflammatory mediator required for the development of experimental lung ischemia-reperfusion injury. The alveolar macrophage is a rich source of tumor necrosis factor-alpha in multiple models of acute lung injury. The present study was undertaken to determine whether the alveolar macrophage is an important source of tumor necrosis factor-alpha in lung ischemia-reperfusion injury and whether suppression of its function protects against injury. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received gadolinium chloride, a rare earth metal that inhibits macrophage function. Injury was quantitated via lung tissue neutrophil accumulation (myeloperoxidase content), lung vascular permeability, and bronchoalveolar lavage fluid leukocyte, cytokine, and chemokine content. Separate samples were generated for immunohistochemistry. RESULTS: Tumor necrosis factor-alpha secretion occurred at 15 minutes of reperfusion and was localized to the alveolar macrophage by immunohistochemistry. In gadolinium-treated animals, lung vascular permeability was reduced by 66% at 15 minutes (P <.03) of reperfusion and by 34% at 4 hours (P <.02) of reperfusion. Suppression of macrophage function resulted in a 35% reduction in lung myeloperoxidase content (P <.03) and similar reductions in bronchoalveolar lavage leukocyte accumulation. Tumor necrosis factor-alpha and microphage inflammatory protein-1alpha protein levels were markedly reduced in the bronchoalveolar lavage of gadolinium-treated animals by enzyme-linked immunosorbent assay. CONCLUSIONS: The alveolar macrophage secretes tumor necrosis factor-alpha protein by 15 minutes of reperfusion, which orchestrates the early events that eventually result in lung ischemia-reperfusion injury at 4 hours. Gadolinium pretreatment markedly reduces tumor necrosis factor-alpha elaboration, resulting in significant protection against lung ischemia-reperfusion injury.