Heart energy metabolism after intestinal ischaemia and reperfusion

Background/purpose

Multiple organ failure subsequent to intestinal ischaemia and reperfusion (I/R) includes cardiac failure, but little is known about heart energy metabolism in this setting. This study investigates the effects of intestinal I/R on heart energy metabolism and evaluates the effects of moderate hypothermia.

Methods

Adult rats underwent intestinal ischaemia for 60 minutes followed by 120 minutes of reperfusion. Animals were maintained at either normothermia (36° to 38°C) or moderate hypothermia (30° to 32°C). In experiment A, 2 groups were studied: (1) sham at normothermia; (2) I/R at normothermia. After death, the heart was removed. Cardiac phosphoenergetics were assessed by ³¹P magnetic resonance spectroscopy; data are expressed as micromoles per gram. In experiment B, 4 groups were studied: (1) sham at normothermia, (2) I/R at normothermia, (3) sham at hypothermia, (4) I/R at hypothermia. At the end of the experiment, the heart was harvested. The activity of carnitine palmitoyl transferase I (CPT I), an important enzyme in the control of fatty acid oxidation, was measured; data are expressed as nanomoles per minute per unit citrate synthase. Results are expressed as mean ± SEM.

Results

In experiment A, there were no differences between the 2 study groups in cardiac phosphocreatine, inorganic phosphate, adenosine triphosphate (ATP), or in the ratio of inorganic phosphate to ATP. In experiment B, CPT I activity was decreased significantly after I/R at normothermia compared with normothermic sham, but this enzyme inhibition was prevented by hypothermia (3.9 ± 0.2; v I/R).

Conclusions

These results suggest that although cardiac ATP supply was maintained during intestinal I/R at normothermia, the balance of substrate utilisation was shifted from fatty acid oxidation to carbohydrate utilisation. However, moderate hypothermia modified these changes. The beneficial effect of moderate hypothermia on cardiac metabolism during intestinal I/R has potential clinical application in various surgical conditions.     

Curcumin Nutrition for the Prevention of Mesenteric Ischemia-Reperfusion Injury: An Experimental Rodent Model

Background

Curcumin is an anti-oxidant molecule known to be a potent inhibitor of nuclear factor-κB (NF-κB). It has been shown to attenuate ischemia/reperfusion (I/R) injury in several organ systems. In this study, we sought to investigate the effects of curcumin on the prevention of superior mesenteric artery I/R injury in rats.

Methods

Wistar albino rats were randomly allocated to 3 groups: group I, sham operated (n = 10); group II, I/R injury only (n = 10); group III, curcumin-treated I/R cohort (n = 10). Group I animals underwent laparotomy without I/R injury. After group II animals underwent laparotomy, 60 minutes of superior mesenteric artery ligation were followed by 3 hours of reperfusion. In the curcumin group, 15 days before I/R, curcumin (40 mg/kg) was administered by gastric gavage. All animals were sacrificed at the end of reperfusion. Intestinal tissue samples were obtained to investigate intestinal mucosal injury; in addition we estimated levels of myeloperoxidase (MPO) activity, malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH), interleukin (IL)-6, and tumor necrosis factor (TNF)-α.

Results

There were statistically significant decreases in GSH levels, along with an increase in intestinal mucosal injury scores, MPO activity, MDA levels, NO, IL-6, and TNF-α in group I when compared with groups II and III (P = .01). Curcumin treatment in group III produced a significant increase in GSH levels, as well as a decrease in intestinal mucosal injury scores, MPO activity, MDA, and NO levels when compared with group II (P < .05).

Conclusion

This study showed that curcumin treatment significantly attenuated reperfusion injury in a superior mesenteric artery I/R model in rats.     

Protective effects of clarithromycin in rats with hypoxia/reoxygenation-induced intestinal injury

Background

This study was designed to determine the role of oxidative stress, nitric oxide (NO), and glutathione-related antioxidant enzymes in rat pups with hypoxia/reoxygenation (H/R)-induced bowel injury and to evaluate the potential benefits of prophylactic clarithromycin.

Methods

One-day-old Wistar albino rat pups (N = 21) were randomly divided into 3 groups: group I (control), group II (exposed to H/R), and group III (clarithromycin + H/R). Clarithromycin was administered (40 mg/kg) subcutaneously to group III for 3 days. On the fourth day, all rats except controls were exposed to H/R and were killed at 6 hours after H/R. Histopathologic injury scores (HIS), malonyldialdehyde, glutathione (GSH), glutathione-peroxidase (GSH-Px) activities, and NO levels were measured on intestinal samples.

Results

Whereas there was no difference for malonyldialdehyde levels among groups, HIS and NO levels were higher in group II than groups I and III (P < .05). However, GSH and GSH-Px activities were lower in group II than groups I and III (P < .05). Clarithromycin significantly increased GSH and GSH-Px activities and reduced HIS and NO levels in group III.

Conclusion

This study showed that oxidative stress and NO contributed to the pathogenesis of H/R-induced bowel injury and that clarithromycin had a protective effect on bowel injury owing to anti-inflammatory and antioxidant effects.     

Pre-treatment with glutamine attenuates lung injury in rats subjected to intestinal ischaemia-reperfusion

Background

Glutamine (Gln) is the most abundant amino acid in blood and tissue fluids and is considered to be essential in certain catabolic conditions. A series of studies has shown that glutamine can attenuate cytokine release, reduce organ damage and improve survival in a rat model of endotoxaemia. The hypothesis for this rat model study is that pre-treatment with Gln reduces the expression of ICAM-1 and attenuates lung injury induced by intestinal ischaemia-reperfusion (I/R).

Methods

Sprague-Dawley rats were randomised into five groups, namely sham group (sham surgery), Gln groups (three different doses) and control group. Lung injury caused by intestinal I/R was evaluated using Evans blue dye concentration and histopathologic examination. The level of myeloperoxidase (MPO) was measured using biochemistry method. The expression of heat shock protein 70 (HSP 70) and ICAM-1 were detected using Western blot and real-time polymerase chain reaction (PCR) methods, respectively.

Results

Compared with the control group, rats pre-treated with Gln before intestinal I/R demonstrated decreased Evans Blue content and MPO activities in lung tissue, reduced the expression of ICAM-1, attenuated lung injury evidenced by pathological change compared with lactated Ringer pre-treated rats. Gln administration increased HSP 70 mRNA and protein expression in lung tissue compared with control group.

Conclusion

Ischaemia-reperfusion injury increases the expression of ICAM-1 in the lung. This may contribute to the migration, accumulation and activation of neutrophils. Pre-treatment with Gln attenuates rat lung injury and reduces ICAM-1 expression.     

Recombinant Human Erythropoietin Pretreatment Attenuates Heart Ischemia-Reperfusion Injury in Rats by Suppressing the Systemic Inflammatory Response

Background

Ischemia-reperfusion (I/R) injury may influence graft function after transplantation. Erythropoietin (EPO) attenuates I/R injury in various animal organs such as intestine, brain, and kidney.

Objective

To evaluate the effects of pretreatment with recombinant human EPO (rhEPO) on I/R-induced heart injury.

Materials and Methods

A rat model of I/R injury was established by ligating the left descending coronary artery for 30 minutes, followed by reperfusion for 4 hours. Fifty Sprague-Dawley rats were divided into 5 groups: sham operation; I/R; I/R+rhEPO, 100 U/kg; I/R+rhEPO, 1000 U/kg; and I/R+rhEPO, 5000 U/kg. Electrocardiograms were assessed continuously to note arrhythmia caused by reperfusion. Serum concentrations of interleukin (IL)-6 and IL-8, and tumor necrosis factor-α were measured at 2 and 4 hours after reperfusion.

Results

The rhEPO-treated animals exhibited dosage-dependent significant reduction in the incidence of ventricular arrhythmia caused by reperfusion, and markedly decreased serum concentrations of IL-6, IL-8, and tumor necrosis factor-α (P < .05) compared with the I/R group (P < .05).

Conclusion

The rhEPO attenuates myocardial I/R injury in rats, at least in part related to inhibition of the system inflammatory response.     

Cold Ischemia Time Influences Spermatogenesis in a Testicular Ischemia/Reperfusion Injury Model

Objective

To evaluate the influence of cold ischemia time on spermatogenesis in a rabbit model of testicular ischemia-reperfusion (I/R) injury.

Material and Methods

The testicular I/R model was established in 24 male white rabbits. The left testes were preserved using HC-A solution at 0°C to 4°C. Cold ischemia time was 1, 2, 4, and 6 hours. The right testes without vascular occlusion were used as autologous controls. Twenty-four hours after reperfusion, the animals were sacrificed, and samples were obtained at bilateral orchiectomy. Another 8 normal testes were used as normal controls. Testicular tissue Johnsen score, malondialdehyde concentration, and apoptosis index were used to evaluate spermatogenesis.

Results

The Johnsen score decreased and the apoptosis index increased with the duration of cold ischemia time in the I/R groups. The malondialdehyde concentration in the I/R groups was significantly higher than the sham and normal groups, and was highest at 4 hours of cold ischemia time.

Conclusion

Testicular I/R injury is highly related to cold ischemia time. In rabbit models, testis transplantation is best performed within 4 hours of cold ischemia with traditional hypothermic protection.     

Evaluation of cysteine effect on redox potential of porcine liver preserved by simple hypothermia

Introduction

Cysteine (cys), a thiol amino-acid, is involved in de novo glutathione (GSH) synthesis in the extra- and intracellular space. It is also probably involved in the anaerobic glycolysis process. Both these facts may affect the metabolic condition of the liver preserved by simple hypothermia for transplantation. The aim of the study was to verify whether cysteine addition to histidine-tryptophan-ketoglutarate (HTK) organ preservation solution showed a positive effect on liver redox potential after 12-hour preservation in simple hypothermia.

Materials and methods

After collecting livers of Great White breed pigs that underwent 30 min of warm ischemia, before 30-min perfusion and cooling to 4°C with modified HTK solution containing cysteine prior to 12 h of preservation. Activity of glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) was determined in liver homogenates after perfusion and after the preservation period. The results were compared with pure HTK, Ringer's and reference University of Wisconsin (UW) solutions.

Results

30 min of perfusion and 12 h of cold preservation (CIT) in the Ringer's solution markedly increased GPx, SOD, and GR activities in liver homogenates compared with the activity using other fluids. After 12-h CIT the activities of GR, GPx and SOD were significantly higher in cys-modified HTK solution than the control HTK solution. They were comparable to the values recorded for the UW group.

Conclusions

Addition of cys to the HTK solution positively influenced the total pool of free radical scavengers in a liver undergoing 12-hour ischemia in the simple hypothermia, which was reflected in the elevated redox enzyme activity possibly due to cys participation in GSH synthesis.     

Timing, route, and dose of administration of heparin-binding epidermal growth factor-like growth factor in protection against intestinal ischemia-reperfusion injury

Purpose

We have previously demonstrated that heparin-binding epidermal growth factor-like growth factor (HB-EGF) is an intestinal cytoprotective agent. The current study examined whether HB-EGF is effective as salvage therapy as well as prophylactic therapy for intestinal ischemia-reperfusion (I/R) injury, whether intravenous administration is as effective as intraluminal administration, and whether increased benefits are seen with increasing dose.

Methods

Total midgut I/R injury in rats was achieved by occlusion of a first-order branch of the superior mesenteric artery for 60 minutes, followed by reperfusion for 6 hours. Rats were treated with HB-EGF 5 minutes before ischemia, halfway through the ischemic event, or 5 minutes after ischemia. Route of administration was tested by administering HB-EGF either intraluminally or intravenously. Seven different doses of HB-EGF were tested.

Results

Heparin-binding, EGF-like growth factor protected the intestine from injury when administered before injury and was also effective when administered during ischemia or even after injury. Intraluminal administration of HB-EGF was superior to intravenous administration. Increasing doses of HB-EGF resulted in a greater cytoprotective effect.

Conclusion

These data demonstrate that HB-EGF acts as an effective intestinal cytoprotective agent when administered intraluminally not only before injury, but also during injury and, most importantly, even after intestinal injury has already occurred. These findings support a basis for the prophylactic use of intraluminal HB-EGF in high-risk patients, as well as for the administration of HB-EGF to salvage patients in whom an intestinal insult has already occurred.     

The Protective Effect of Aprotinin and α-Tocopherol on Ischemia-Reperfusion Injury of the Rat Liver

Background

Liver injury caused by ischemia-reperfusion (I/R) processes is a complication of hepatic resection surgery and transplantation, particularly using grafts from marginal donors. Despite improvements in organ preservation and advances in surgical techniques, I/R injury remains a significant clinical problem. In this study, we investigated whether aprotinin provided protection against the adverse effects of I/R injury in liver tissue.

Methods

Forty rats were randomized into four groups (n = 10): group I: (control group) I/R + no medication; group II: sham-operated group + no medication or I/R; group III: I/R + aprotinin; group IV: I/R + α-tocopherol. Malondialdehyde (MDA) was measured in the liver tissue and superoxide dismutase (SOD), catalase (CAT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), as well as lactate dehydrogenase (LDH) in rat serum.

Results

Administration of aprotinin and α-tocopherol before I/R resulted in significant reductions of MDA levels compared to the I/R alone group (group I; P = .01 and P < .01, respectively). Administration of aprotinin or α-tocopherol prior to I/R resulted in significant increases in SOD and CAT levels compared with the I/R group (P < .05 each). Compared to the I/R group, significant decreases in plasma AST, ALT, and LDH levels were observed both in the aprotinin and in the α-tocopherol group (P < .05). Histological evaluation revealed the injury grade to be relatively lower among groups III and IV compared to group I.

Discussion

In conclusion, rat hepatic structures in aprotinin and α-tocopherol administered groups were well protected. Therefore, aprotinin may provide protection against the adverse effects of I/R injury in liver transplantation.     

Protective effects of Ginkgo biloba extract in rats with hypoxia/reoxygenation-induced intestinal injury

Background

The purpose of this study is to investigate the protective effects of Ginkgo biloba extract (EGb 761) in rat pups with hypoxia/reoxygenation (H/R)-induced bowel injury.

Methods

One-day-old Wistar albino rat pups (n = 21) were randomly divided into 3 groups: group 1 (control, untreated and not exposed to H/R, n = 7), group 2 (untreated but exposed to H/R, n = 7), and group 3 (EGb 761 + H/R, n = 7). Ginkgo biloba extract was administered (100 mg/kg per day, subcutaneously) to group 3 for 3 days. On the fourth day, all animals except controls were exposed to H/R and were killed 6 hours after H/R. Histopathologic injury scores (HIS), malondialdehyde, glutathione (GSH), GSH-peroxidase (Px) activities, and nitric oxide (NO) levels were measured on intestinal samples.

Results

Although the control group had normal HIS, group 2 had grade 3 HIS. In contrast, group 3 had minimal HIS, and these results were significantly better than those of group 2 (P < .001). Malondialdehyde and NO levels of group 3 were significantly lower than those of group 2 (P < .01). Glutathione and GSH-Px activities of group 1 were higher than those of groups 2 and 3 (P < .05). However, there were no significant differences for GSH and GSH-Px activities between groups 2 and 3.

Conclusions

This study showed that hypoxia and NO contributed to the pathogenesis of H/R-induced intestinal injury and that prophylactically administered EGb 761 had a protective effect on bowel injury.     

Preischemic treatment with melatonin attenuates liver reperfusion-induced impairment of cardiac function

Objectives

Cardiac functional impairment is frequently observed in patients with end-stage liver disease and after reperfusion of an ischemic liver. Excessive production of reactive oxygen species (ROS) through activation of Kupffer cells and leukocytes during reperfusion may play important roles. We evaluated the cardiac protective effects of preischemic treatment with melatonin.

Methods

Studies were performed on 3 groups of male Sprague-Dawley rats; shame-operated controls, liver ischemia and reperfusion (I/R), and melatonin pretreatment prior to I/R. Liver I/R was performed by clamping the hepatic artery and portal vein for 30 minutes, followed by releasing the clamps for 2 hours. The cardiac function was assessed using a high-fidelity dual pressure-volume catheter positioned in the left ventricle (LV). We also evaluated heart injury using plasma creatine kinase-MB (CKMB), and Troponin I (cTnI). The level of hydroxyl radical production was evaluated using plasma methylguanidine (MG).

Results

LV function was severely impaired after 2 hours of reperfusion; stroke volume and LV contractility were significantly reduced (P < .05). Markedly increased CKMB and cTnI indicated serious myocardial injury. Preischemic treatment with melatonin protected the heart as seen by the reduced plasma CKMB and cTnI (P < .05), and decreased systemic hydroxyl radical production.

Conclusions

Liver I/R severely impaired cardiac functions by production of hydroxyl radicals. Melatonin pretreatment effectively scavenged oxidants and hydroxyl radicals, protecting cardiac function against liver I/R-induced injury.     

Protective effect of melatonin on liver ischemia-reperfusion induced pulmonary microvascular injury in rats

Objective

Reactive oxygen species generated during liver reperfusion have been implicated in remote lung injury. In this study, we evaluate the protective effects of melatonin pretreatment against the increased pulmonary microvascular permeability.

Methods

Male Sprague-Dawley rats were divided into three groups: shame-operated, liver ischemia-reperfusion (I/R), and melatonin pretreated (15 mg/kg, intraperitoneally) 15 minutes prior to the liver I/R). The duration of ischemia was 30 minutes, followed by 2 hours of reperfusion. Lungs were isolated in situ and parameters of the capillary filtration coefficient (K_fc), lung wet-to-dry weight ratio (W/D), lung weight-to-body weight (LW/BW), and protein concentration in bronchial lavage fluid (PCBAL), the percentage of macrophages and neutrophils in bronchial lavage fluid (BALF), and lung tissue malonedealdehyde were used to assess the lung injury.

Results

Liver I/R-induced lung injury was noted by the markedly increased K_fc, W/D, LW/BW, PCBAL, and the presence of neutrophils and macrophages in BALF. Lipid peroxidation was also increased (P < .05). All indicators were markedly decreased in melatonin-pretreated rats (P < .05), suggesting that lung injury was attenuated.

Conclusions

Melatonin pretreatment prior to liver I/R can effectively reduce the pulmonary microvascular permeability and attenuate lipid peroxidation in the lungs.     

Liver reperfusion-induced decrease in dynamic compliance and increase in airway resistance are ameliorated by preischemic treatment with melatonin through scavenging hydroxyl radicals in rat lungs

Objectives

Acute lung injury is frequently observed in patients subsequent to liver ischemia and reperfusion (I/R) injury. However, the changes in pulmonary function, eg, lung dynamic compliance (C_dyn) and airway resistance (RI), are not well understood. We sought to study the alternations in pulmonary function during liver I/R and the protective effects of preischemic treatment with melatonin.

Methods

Animals were divided into 3 groups: sham-operated, liver I/R, and intraperitoneal (i.p.) pretreatment with melatonin (15 mg/kg). Liver I/R was performed by clamping the hepatic artery and portal vein for 30 minutes followed by releasing for 2 hours. The C_dyn and RI were studied at baseline and at 2 hours of reperfusion. We assessed the level of pulmonary hydroxyl radicals by methylguanidine (MG) content in the bronchoalveolar lavage fluid (BALF) as well as the liver damage using plasma levels of lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT).

Results

After 2 hours of liver reperfusion, C_dyn was reduced by ∼25%, while RI increased by ∼16% (P < .05). The decreased C_dyn and increased RI were markedly attenuated by melatonin pretreatment (P < .05). Melatonin pretreatment also protected the liver against I/R injury (P < .05), as seen by reduced LDH, GOT and GPT along with markedly reduced hydroxyl radicals (P < .05).

Conclusions

Preischemic treatment with melatonin protected lung function against damage by liver I/R. The improvement in lung function was strongly associated with decreased hydroxyl radicals in the lungs.     

Twelve-year experience with left atrial resection in the treatment of non-small cell lung cancer

Background

We retrospectively reviewed our 12-year experience in the surgical treatment of non-small cell lung cancer invading the left atrium. End points of the study were overall survival and factors potentially affecting survival.

Methods

Nineteen consecutive patients with lung cancer invading the left atrium underwent surgery. Three patients with N2 disease underwent induction chemotherapy. Patients with either incomplete resections or pN2 disease received postoperative chemoradiotherapy.

Results

Five-year survival was 14%, and the median survival time was 25 months. These figures refer to a very homogeneous group of patients with respect to the extent of atrial infiltration. Patients with N2 disease tended to have a worse outcome than patients with N0 or N1 disease (p = 0.06). The 3 patients with N2 disease who underwent induction chemotherapy were alive and disease-free at 30, 15, and 11 months from surgery. Survival was not affected by histology, type of surgery, or completeness of resection. Three patients with residual cancer in the atrial resection margin underwent postoperative chemoradiotherapy and are alive at 25, 17, and 15 months after surgery.

Conclusions

In spite of the poor survival rates we report, the present experience suggests that more-favorable results could be expected by the routine preoperative use of positron emission tomographic scan staging, a more-extensive assessment of atrial invasion, the application of induction chemotherapy in patients with N2 disease, and postoperative chemoradiotherapy in patients with tumors abutting the atrial resection margin.     

CXC chemokines play a critical role in liver injury, recovery, and regeneration

Background

Hepatic ischemia/reperfusion (I/R) injury is a principal consideration of trauma, resectional liver surgery, and transplantation. Despite improvements in supportive care, hepatic I/R injury continues to negatively impact patient outcomes because of significant tissue damage and organ dysfunction. CXC chemokines have been implicated as key mediators in the deleterious inflammatory cascade after hepatic I/R and also as important, beneficial regulators of liver recovery and regeneration. As such, their potential to mediate both beneficial and detrimental effects on hepatocytes makes them a key target for therapy. Herein, we provide a review of the inflammatory mechanisms of hepatic I/R injury, with a focus on the divergent functions of CXC chemokines in this response compared with other liver insults, and offer an explanation of this apparent paradox.

Data sources

MEDLINE and PubMed.

Conclusions

CXC chemokines are key mediators of both the inflammatory response to hepatic I/R as well as the recovery from this injury. Their contrasting functions in the regeneration of liver mass after an ischemic insult indicates that therapeutic manipulation of these mediator pathways should differ depending on the surgical milieu.     

Toll-like receptor 4 is protective against neonatal murine ischemia-reperfusion intestinal injury

Purpose

Premature infants receiving probiotics have a decreased incidence of necrotizing enterocolitis. This may be mediated by intestinal bacterial signaling via toll-like receptors (TLRs) 2 and 4 maintaining intestinal homeostasis. We hypothesized that TLRs 2 and 4 are protective against ischemia-reperfusion (I/R) intestinal injury.

Methods

Two-week-old C57BL/6 wild-type (WT), B6.TLR2^−/−, B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and microbially reduced (antibiotic-treated) mice (MR) underwent 60 minutes of superior mesenteric artery occlusion (I) followed by 90 minutes of reperfusion (R). Small intestine was harvested for analysis of microscopic injury, apoptosis, and inflammatory gene expression using quantitative polymerase chain reaction.

Results

After I/R, the median histologic injury scores of the B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and MR pups were higher than the WT or B6.TLR2^−/− pups that corresponded with greater apoptosis based on terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labeling and activated caspase-3 immunostaining. B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and MR also had elevated tissue innate immunity-associated chemokine and cytokine expression.

Conclusions

Neonatal mice deficient in TLR4, either alone or also deficient in TLR2, as well as those lacking a normal commensal intestinal microbiome are more susceptible to an I/R model of intestinal injury. These results may provide a mechanism for commensal bacterial-mediated protection, which may help to direct further studies to elucidate the mechanism of probiotic protection.