The role of glutamine in skeletal muscle ischemia/reperfusion injury in the rat hind limb model

Study on the acute toxicity of trichlorfon and its breakdown product dichlorvos to goldfish (Carassius auratus) based on 1H NMR metabonomics

Trichlorfon, one of the most widely used organophosphate insecticides, is commonly employed in aquaculture and agriculture to combat parasitic infestations. However, its inherent instability leads to rapid decomposition into dichlorvos (DDVP), increasing its toxicity by eightfold. Therefore, the environmental effects of trichlorfon in real-world scenarios involve the combined effects of trichlorfon and its degradation product, DDVP. In this study, we systematically investigated the degradation of trichlorfon in tap water over time using HPLC and LC-MS/MS analysis. Subsequently, an experiment was conducted to assess the acute toxicity of trichlorfon and DDVP on goldfish (Carassius auratus), employing a 1H NMR-based metabolic approach in conjunction with serum biochemistry, histopathological inspection, and correlation network analysis. Exposure to trichlorfon and its degradation product DDVP leads to increased lipid peroxidation, reduced antioxidant activity, and severe hepatotoxicity and nephrotoxicity in goldfish. Based on the observed pathological changes and metabolite alterations, short-term exposure to trichlorfon significantly affected the liver and kidney functions of goldfish, while exerting minimal influence on the brain, potentially due to the presence of the blood-brain barrier. The changes in the metabolic profile indicated that trichlorfon and DDVP influenced several pathways, including oxidative stress, protein synthesis, energy metabolism, and nucleic acid metabolism. This study demonstrated the applicability and potential of 1H NMR-based metabonomics in pesticide environmental risk assessment, providing a feasible method for the comprehensive study of pesticide toxicity in water environments.

24-hour Perfusion of Porcine Myocutaneous Flaps Mitigates Reperfusion Injury: A 7-day Follow-up Study

Background:

Static cold storage is the gold standard of preservation in vascularized composite allotransplantation and allows a preservation time of 4–6 hours. Machine preservation is a promising technique for prolonged preservation; however, studies on extended preservation that compare different preservatives are scarce. This study aims to assess the feasibility of 24-hour acellular perfusion and compares different preservation solutions in a porcine myocutaneous flap replantation model.

Methods:

Six harvested bilateral myocutaneous flaps of three Dutch Landrace pigs were perfused hypothermically for 24 hours with University of Wisconsin machine perfusion solution (UW-MPS; n = 2) or histidine-tryptophan-ketoglutarate solution (HTK; n = 2) or preserved on ice for 4 hours (n = 2) before orthotopic replantation. Animals were observed for 7 days after replantation. Skeletal muscle injury was assessed by biochemical markers during perfusion, and muscle biopsies were analyzed for ischemia reperfusion injury directly after preservation and at 1, 3, and 7 days after replantation.

Results:

Markers of muscle damage varied during perfusion, but decreased overall in both perfusion groups. Flap weight increased 60% and 97% in the HTK-perfused flaps, compared with -6% and -7% in the UW-MPS-perfused flaps after 24 hours. Histopathologic evaluation demonstrated decreased muscle damage in flaps perfused with HTK compared with the UW-MPS-perfused flaps at 1 week after replantation.

Conclusions:

Machine perfusion of myocutaneous flaps for 24 hours with subsequent replantation is feasible, but warrants further research. Perfusion with HTK solution seemed to result in better histological outcomes 7 days after reperfusion compared with UW-MPS.

Metabolic Intersection of Cancer and Cardiovascular Diseases: Opportunities for Cancer Therapy

According to data from the World Health Organization, cardiovascular diseases and cancer are the two leading causes of mortality in the world [1]. Despite the immense effort to study these diseases and the constant innovation in treatment modalities, the number of deaths associated with cardiovascular diseases and cancer is predicted to increase in the coming decades [1]. From 2008 to 2030, due to population growth and population aging in many parts of the world, the number of deaths caused by cancer globally is projected to increase by 45%, corresponding to an annual increase of around four million people [1]. For cardiovascular diseases, this number is six million people [1]. In the United States, treatments for these two diseases are among the most costly and result in a disproportionate impact on low- and middleincome people. As the fight against these fatal diseases continues, it is crucial that we continue our investigation and broaden our understanding of cancer and cardiovascular diseases to innovate our prognostic and treatment approaches. Even though cardiovascular diseases and cancer are usually studied independently [2-12], there are some striking overlaps between their metabolic behaviors and therapeutic targets, suggesting the potential application of cardiovascular disease treatments for cancer therapy. More specifically, both cancer and many cardiovascular diseases have an upregulated glutaminolysis pathway, resulting in low glutamine and high glutamate circulating levels. Similar treatment modalities, such as glutaminase (GLS) inhibition and glutamine supplementation, have been identified to target glutamine metabolism in both cancer and some cardiovascular diseases. Studies have also found similarities in lipid metabolism, specifically fatty acid oxidation (FAO) and synthesis. Pharmacological inhibition of FAO and fatty acid synthesis have proven effective against many cancer types as well as specific cardiovascular conditions. Many of these treatments have been tested in clinical trials, and some have been medically prescribed to patients to treat certain diseases, such as angina pectoris [13, 14]. Other metabolic pathways, such as tryptophan catabolism and pyruvate metabolism, were also dysregulated in both diseases, making them promising treatment targets. Understanding the overlapping traits exhibited by both cancer metabolism and cardiovascular disease metabolism can give us a more holistic view of how important metabolic dysregulation is in the progression of diseases. Using established links between these illnesses, researchers can take advantage of the discoveries from one field and potentially apply them to the other. In this chapter, we highlight some promising therapeutic discoveries that can support our fight against cancer, based on common metabolic traits displayed in both cancer and cardiovascular diseases.

Studies on Protection of Astaxanthin from Oxidative Damage Induced by H2O2 in RAW 264.7 Cells Based on 1H NMR Metabolomics

Astaxanthin (AST) is a fat-soluble and non-vitamin A source of carotenoid that can quench reactive oxygen species and it has strong antioxidant and anti-inflammatory abilities. Herein, we have used H₂O₂ to establish a model of oxidative damage to RAW 264.7 cells and cells treated with vitamin C as the positive control group. The changes in metabolome were examined using ¹H NMR and the results demonstrated that H₂O₂ treatment and various metabolic pathways such as amino acid, glucose, and glycerolipid metabolism were downregulated, which in turn affected citric acid cycle and energy status. AST could reverse downregulation of some of these metabolic pathways to a certain extent, and reduce cellular oxidative stress and death. The AST group differed from the vitamin C group in regulating d-glutamine, d-glutamic acid, pyruvate, and glycerolipid metabolism. The experimental results help to further understand the antioxidant effects of AST.

The Emerging Role of l-Glutamine in Cardiovascular Health and Disease

Emerging evidence indicates that l-glutamine (Gln) plays a fundamental role in cardiovascular physiology and pathology. By serving as a substrate for the synthesis of DNA, ATP, proteins, and lipids, Gln drives critical processes in vascular cells, including proliferation, migration, apoptosis, senescence, and extracellular matrix deposition. Furthermore, Gln exerts potent antioxidant and anti-inflammatory effects in the circulation by inducing the expression of heme oxygenase-1, heat shock proteins, and glutathione. Gln also promotes cardiovascular health by serving as an l-arginine precursor to optimize nitric oxide synthesis. Importantly, Gln mitigates numerous risk factors for cardiovascular disease, such as hypertension, hyperlipidemia, glucose intolerance, obesity, and diabetes. Many studies demonstrate that Gln supplementation protects against cardiometabolic disease, ischemia-reperfusion injury, sickle cell disease, cardiac injury by inimical stimuli, and may be beneficial in patients with heart failure. However, excessive shunting of Gln to the Krebs cycle can precipitate aberrant angiogenic responses and the development of pulmonary arterial hypertension. In these instances, therapeutic targeting of the enzymes involved in glutaminolysis such as glutaminase-1, Gln synthetase, glutamate dehydrogenase, and amino acid transaminase has shown promise in preclinical models. Future translation studies employing Gln delivery approaches and/or glutaminolysis inhibitors will determine the success of targeting Gln in cardiovascular disease.

The relation of oxidative stress and apoptosis to histopathologic alterations in the lungs as a result of global cerebral ischemia

Heart attack and oxygen deficiency may cause necrosis in the brain and other tissues. We investigated the histopathological effects of nitric oxide (NO) on ischemia/reperfusion in lung and hippocampus using a rat brain bilateral occlusion ischemia model. Male rats were assigned to sham (SH), ischemic preconditioning (PC), global ischemia (GI) and ischemic reperfusion (IR) groups. Before ischemia was induced, blood was drawn to induce hypovolemic hypotension and for blood gas testing. After sacrifice, samples of hippocampus were harvested. Sections were examined using hematoxylin and eosin (H & E) staining and immunostaining using primary antibodies for GFAP, S100β, iNOS, eNOS and the TUNEL method. Following ischemia, we found evidence of gliosis induced oxidative stress and apoptosis in the hippocampus. No significant differences were detected between the SH and PC groups. In the GI and IR groups, apoptosis and necrosis were observed in the hippocampus. Lung sections were stained with H & E and Masson's trichrome (MT) and immunostained for iNOS and eNOS. The TUNEL method was used to detect apoptosis. Interstitial edema, vascular congestion, intra-alveolar hemorrhage, perivascular edema, neutrophil infiltration and disruption of alveoli were observed after global ischemia and ischemic reperfusion. Inflammatory cells were detected in the connective tissue. The IR and GI groups exhibited significantly more apoptotic cells than the SH or PC groups. Free radicals, such as nitric oxide (NO), that appear following ischemia and reperfusion in the brain may also injure the lungs. Increased NO in both lung and brain tissue suggests that apoptosis in these organs can be induced by reactive nitrogen species.

Effects of Glutathione on Mechanical Allodynia and Central Sensitization in Chronic Postischemic Pain Rats

Background

The chronic postischemia pain (CPIP) model is an animal model using ischemia/reperfusion injury that mimics the symptoms of complex regional pain syndrome type I. Glutathione (GSH) prevents ischemia/reperfusion injury by scavenging free radicals. We conducted this study to investigate the protective effect of GSH in CPIP rats via changes of mechanical allodynia and phospholyration of the N-methyl-D-aspartate receptor subunit GluN1.

Methods

We divided 45 rats into 5 groups: sham, CPIP, CPIP + GSH 100 mg/kg, CPIP + GSH 200 mg/kg, and CPIP + GSH 500 mg/kg. Rats in the sham and CPIP groups received normal saline and rats in the other groups received GSH at the designated doses thirty minutes prior to reperfusion. Withdrawal thresholds were evaluated before sugery as well as 1, 3, and 7 days after surgery. pGluN1 level in the spinal cord was also measured.

Results

GSH treated rats show a significant increase in the withdrawal thresholds of both hind paws as compared with the CPIP group dose-dependently. The expression of pGluN1 in the GSH treated rats significantly decreased as compared to the CPIP group (all P < 0.05).

Conclusion

These findings suggest that GSH inhibited the development of mechanical allodynia and central sensitization in CPIP rats.

Improvement of Pancreatic Islet Isolation Outcomes Using Glutamine Perfusion during Isolation Procedure

During procurement, isolation, and transplantation, islets are exposed to high levels of oxidative stress triggering a variety of signaling pathways that can ultimately lead to cell death. Glutamine is an important cellular fuel and an essential precursor for the antioxidant glutathione. The aim of this study was to examine the role of intraductal glutamine administration in facilitating recovery of isolated rat islets from pancreases subjected to a clinically relevant period of warm ischemia. Islets were isolated in Sprague-Dawley (SD) rats (n= 18 per group). Pancreata in groups 1 and 2 were procured immediately while groups 3 and 4 were subjected to 30-min warm ischemia. Groups 2 and 4 were treated intraductally with 5 mM glutamine prior to pancreatectomy. Exposure to 30-min warm ischemia significantly reduced islet yield [groups 1 & 2 (nonischemia): 503 ± 29 islets/rat vs. groups 3 & 4 (ischemia): 247 ± 26 islets/rat; p < 0.05]. Intraductal glutamine treatment significantly improved islet yield when pancreata were subjected to 30-min warm ischemia [144 ± 16 islets/rat without glutamine (group 3) vs. 343 ± 36 islets/rat with glutamine (group 4), p < 0.05]. Glutamine also significantly improved islet viability (values were 50 ± 4% in group 4 vs. 27 ± 3% in group 3, p < 0.05). Similarly, glutathione (reduced) levels were significantly elevated in both glutamine-treated groups; however, this increase was greatest in tissues exposed to ischemia (2.76 ± 0.04 nmol/mg protein in group 4 vs. 1.66 ± 0.04 nmol/mg protein in group 3, p < 0.05). Intraductal glutamine administration considerably improves the islet yield, viability, and augments endogenous glutathione levels in pancreata procured after a clinically relevant period of ischemia. Intraductal administration of glutamine at the time of digestive enzyme delivery into the harvested pancreas may represent a simple yet effective tool to improve islet yields in clinical isolations.

Glutamine Administration After Sublethal Lower Limb Ischemia Reduces Inflammatory Reaction and Offers Organ Protection in Ischemia/Reperfusion Injury

BACKGROUND

This study investigated the effects of intravenous glutamine (GLN) administration on the expression of adhesion molecules and inflammatory mediators in a mice model of hind limb ischemia/reperfusion (IR) injury.

METHODS

There were 3 IR groups and 1 normal control (NC) group. The NC group did not undergo the IR procedure. Mice in the IR groups underwent 90 minutes of limb ischemia followed by a variable period of reperfusion. Ischemia was performed by applying a 4.5-oz orthodontic rubber band to the left thigh. Mice in one IR group were sacrificed immediately after reperfusion. The other 2 IR groups were injected once with either 0.75 g GLN/kg body weight (G group) or an equal volume of saline (S group) via tail vein before reperfusion. Mice in the S and G groups were subdivided and sacrificed at 4 or 24 hours after reperfusion.

RESULTS

IR enhanced the inflammatory cytokine gene expressions in muscle. Also, plasma interleukin (IL)-6 levels, blood neutrophil percentage, and the adhesion molecule and chemokine receptors expressed by leukocytes were upregulated after reperfusion. The IR-induced muscle inflammatory mediator gene expressions, blood macrophage percentage, and plasma IL-6 concentration had declined at an early or a late phase of reperfusion when GLN was administered. Histologic findings also found that remote lung injury was attenuated during IR insult.

CONCLUSIONS

A single dose of GLN administration immediately after sublethal lower limb ischemia reduces the inflammatory reaction locally and systemically; this may offer local and distant organ protection in hind limb IR injury.

Modeling acute traumatic injury

Acute traumatic injury is a complex disease that has remained a leading cause of death, which affects all ages in our society. Direct mechanical insult to tissues may result in physiological and immunologic disturbances brought about by blood loss, coagulopathy, as well as ischemia and reperfusion insults. This inappropriate response leads to an abnormal release of endogenous mediators of inflammation that synergistically contribute to the incidence of morbidity and mortality. This aberrant activation and suppression of the immune system follows a bimodal pattern, wherein activation of the innate immune responses is followed by an anti-inflammatory response with suppression of the adaptive immunity, which can subsequently lead secondary insults and multiple organ dysfunction. Traumatic injury rodent and swine models have been used to describe many of the underlying pathologic mechanisms, which have led to an improved understanding of the morbidity and mortality associated with critically ill trauma patients. The enigmatic immunopathology of the human immunologic response after severe trauma, however, has never more been apparent and there grows a need for a clinically relevant animal model, which mimics this immune physiology to enhance the care of the most severely injured. This has necessitated preclinical studies in a more closely related model system, the nonhuman primate. In this review article, we summarize animal models of trauma that have provided insight into the clinical response and understanding of cellular mechanisms involved in the onset and progression of ischemia-reperfusion injury as well as describe future treatment options using immunomodulation-based strategies.

Does the method of expression of venous blood affect ischaemia/reperfusion damage in tourniquet use? An experimental study on rabbits

The aim of this study was to compare the ischaemia and reperfusion phases of two tourniquet application models (Group 1: expressing the blood by a sterile rubber bandage and Group 2: elevation of the limb for several minutes) using an analysis of ischaemia/reperfusion parameters and blood pH. Sixteen New Zealand rabbits were used. Muscle samples were extracted from the triceps surae; at phase A (baseline: just before tourniquet application), phase B (ischaemia: 3h after tourniquet inflation) and phase C (2h after tourniquet deflation). Nitrite, nitrate, reduced glutathione, myeloperoxidase, malondyaldehyde were measured in the samples. Blood pH was also measured at each phase. Group 2 had significantly decreased nitrite (p=0.007) and nitrate (p=0.01) levels compared to Group 1 while passing from phase A to phase B. The pH decrease through the phases was significant within Group 1 (p=0.006) and was not significant within Group 2 (p=0.052). Lower levels of NO metabolites nitrate and nitrite, result from tourniquet use with incomplete venous blood expression by elevation. Also, with this technique severe acidosis is less likely to occur than when a tourniquet is used with expression of the venous blood by rubber bandage. These findings may help in the decision of which tourniquet technique is to be used for potentially long operations which may exceed 2h.

Effects of glutamine supplementation on muscle function and stress responses in a mouse model of spinal cord injury

Spinal cord injury (SCI) results in loss of muscle function due to rapid breakdown of contractile proteins. Glutamine supplementation improves clinical outcomes, but its effects on muscle function after SCI are unknown. The benefits of glutamine in non-skeletal muscle tissues involve elevated heat shock protein (Hsp)70 and Hsp25, but the muscle response may differ because it is the largest contributor to plasma glutamine. We tested the hypothesis that glutamine preserves muscle function after SCI and that this is associated with increased heat shock protein and reduced inflammatory factors, interleukin-6 (IL-6) and tumour necrosis factor-α (TNFα). Changes in plantarflexor force, fatigability and total myofibrillar, Hsp70, Hsp25, IL-6 and TNFα muscle protein levels were measured 7 days after sham or spinal cord transection surgery in mice receiving daily placebo or glutamine. Compared with placebo, after SCI glutamine significantly attenuated the reductions in maximal isometric force (0.22 ± 0.01 versus 0.31 ± 0.03 N, respectively) and fatigue resistance (34 ± 4 versus 59 ± 4% of initial force, respectively). Glutamine significantly ameliorated the loss of myofibrillar protein with spinal cord transection. Spinal cord transection was associated with decreased Hsp70 and Hsp25 with glutamine only (45 ± 3 and 44 ± 5% of placebo, respectively). Glutamine significantly reduced spinal cord transection-associated increases in IL-6 and TNFα compared with placebo (38 ± 6 and 37 ± 8% of placebo, respectively). Functionally, early reductions in contractile protein, force and fatigue resistance after SCI were reversed with glutamine. Spinal cord transection-associated reductions in Hsp70, Hsp25, IL-6 and TNFα with glutamine versus placebo suggest lower stress in the muscle, possibly related to a reduced need to produce glutamine. These findings support glutamine as a therapeutic intervention to accelerate recovery of muscle function after SCI.

Alterations of biochemical marker levels and myonuclear numbers in rat skeletal muscle after ischemia-reperfusion

Prolonged ischemia-reperfusion results in various damages in skeletal muscle. Following reperfusion, although the damaged muscles undergo regeneration, the precise process and mechanism of regeneration have not yet been fully understood. Here, we show the altered levels of plasma biochemical markers of muscle damage, and the change in myonuclear numbers in adult rat skeletal muscle by ischemia-reperfusion. Male Wistar rats were subjected to unilateral hindlimb ischemia by clamping the anterior tibial artery for 2 h before reperfusion. Both plasma creatine kinase activity and C-reactive protein levels in plasma were increased significantly at 0.5 h of reperfusion and returned to the control level at 24 h. The transverse sectional area of muscle belly of the anterior tibial muscles in ischemic side was significantly decreased by 20 % compared with those in sham-ischemic (control) side at 2 days, and returned to the control level at 5 days of reperfusion. Moreover, the number of interstitial nuclei in the ischemic side were significantly increased at 5-14 days and returned to the control level at 21 days of reperfusion. Central nuclei that are specifically observed in regenerating muscle, appeared at 5 days, reached a peak at 14 days, and disappeared at 28 days of reperfusion. Furthermore, MyoD, a regulatory factor for myogenesis, showed a transient expression at 5 days of reperfusion. These results indicate that, although the size of muscle seems to be recovered by 5 days of reperfusion, the most active muscle regeneration occurs much later, as shown by the increase in central nuclei.

The effects of hypothermia and L-arginine on skeletal muscle function in ischemia-reperfusion injury

OBJECTIVES

Ischemia-reperfusion (I/R) injury can have detrimental effects on skeletal muscle. We have shown that vessel permeability can be minimized in a hypothermic setting and also by administering the nitric oxide synthase (NOS) stimulator, L-arginine, at physiologic temperatures. The purpose of this study was to examine and compare skeletal muscle contractility after an I/R insult during hypothermic conditions, warm conditions, and also with the administration of L-arginine at physiologic temperatures. We hypothesized that hypothermia and L-arginine administration will also demonstrate protective effects to skeletal muscle contractility.

METHODS

Using Sprague-Dawley rats, the extensor digitorum longus muscle was rotated on its vascular pedicle to a thermo-controlled stage. Ischemia was established using an atraumatic femoral artery tourniquet. Reperfusion was performed under control and experimental conditions including local hypothermia and intravenous L-arginine. After harvesting experimental muscles, contractility was then quantified by using a tissue bath stimulator with force transducers.

RESULTS

Warm reperfusion resulted in marked decrease in muscle contractility compared with sham animals. Local hypothermia showed statistically significant preservation of contractility compared with the sham group. This protective effect was recapitulated by the application of NOS inducers (L-arginine) at warm conditions.

CONCLUSIONS

These findings demonstrate that hypothermia and L-arginine are protective of skeletal muscle contractility after an I/R injury. The results presented may have profound effects on future therapeutic recommendations and suggest possible pathways for clinical intervention to modulate I/R injury, which is commonplace in orthopaedic trauma and reconstructive surgery.

Biochemical studies on the cardioprotective effect of glutamine on tissue antioxidant defense system in isoprenaline-induced myocardial infarction in rats

Oxidative stress is one of the mechanisms with a central role involved in the pathogenesis of myocardial infarction. The protective effect of glutamine on myocardial antioxidant defense system was investigated during isoprenaline-induced myocardial infarction, an animal model of myocardial infarction of human beings. Levels of diagnostic marker enzymes in plasma, reduced glutathione (GSH) and lipid peroxides and the activities of glutathione peroxidase, glutathione-S-transferase, catalase and superoxide dismutase in heart tissue were determined. Injection of isoprenaline caused significant increases in the levels of diagnostic marker enzymes in plasma and lipid peroxidation in heart tissue. A parallel decline in the levels of ATP (Adenosine triphosphate) and GSH and the activities of glutathione-dependent antioxidant enzymes and antiperoxidative enzymes in heart tissue was also observed. Prior oral administration of glutamine significantly prevented isoprenaline-induced adverse effects and maintained myocardial antioxidant status at near normal status. The cardioprotective effect of glutamine is probably related to a strengthening of the myocardial membrane by its membrane stabilizing action, or to a counteraction of free radicals by its antioxidant property, or to its ability to maintain near to normal status the activities of free radical scavenging enzymes and the level of GSH, which protect myocardial membrane against oxidative damage by decreasing lipid peroxidation.

Beneficial effects of clopidogrel on glycemic indices and oxidative stress in patients with type 2 diabetes

Objective of present study is to evaluate the possible role of clopidogrel in improving glycemic indices and oxidative stress in patients with type 2 diabetes. This study was performed on 42 uncontrolled type 2 diabetic patients at the specialized center for Endocrinology and Diabetes, Al-Rasafa Directorate of Health, Baghdad. All of the patients were treated with (glibenclamide 5 mg at morning) and randomized into two groups: the first group includes 22 patients treated with clopidogrel tablets (75 mg/day) for 2 months; the second group includes 20 patients treated with a placebo formula (sodium bicarbonate 200 mg/day) for the same period. Treatment with clopidogrel produced significant improvement (P < 0.05) in fasting serum glucose (FSG), fasting serum insulin level, quantitative insulin sensitivity check index (QUICKI); and oxidative stress markers: serum malondialdehyde (MDA) and serum reduced glutathione (GSH) compared to their baseline levels. There was significant elevation (P < 0.05) in both FSG and fasting serum insulin and the MDA level with significant reduction (P < 0.05) in QUICKI of placebo group compared to their baseline levels. However, clopidogrel produced significant elevation (P < 0.05) in AST and ALT levels but placebo formula caused no significant alteration (P > 0.05) in the serum levels of these two enzymes. In conclusion the treatment with clopidogrel improved glycemic indices and reduced oxidative stress in patients with type 2 diabetes.

Glutamine treatment attenuates the development of organ injury induced by zymosan administration in mice

Glutamine is the most abundant amino acid in the bloodstream. It is important in nucleotide synthesis, is anti-catabolic, has anti-oxidant properties via metabolism to glutathione, may enhance immune responsiveness and possesses immunoregulatory functions. Moreover, it reduces atrophy of intestinal mucosa in animals on total parenteral nutrition and prevents intestinal mucosal injury accompanying small bowel transplantation, chemotherapy and radiation. In the present study, we investigated the effects of glutamine on development of non-septic shock caused by zymosan. Mice received either zymosan (500 mg/kg, administered i.p., as a suspension in saline) or vehicle (saline). Glutamine (1.5 mg/kg i.p.) was administered 1 and 6h after zymosan administration. Organ failure and systemic inflammation in mice were assessed 18 h after administration of zymosan and/or glutamine. Glutamine-treatment reduced the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan-injection and also attenuated the pancreatic and gut injury. Inflammatory and apoptotic parameters were evaluated to better investigate the effects of the glutamine-administration. So, by immunohistochemical analysis and in vitro assays, we have clearly showed that glutamine reduces: 1) the histological damage in pancreas and gut; 2) the inducible nitric oxide synthase expression; 3) nitrotyrosine and poly (ADP-ribose) formation; 4) TNF-α and IL-1β tissue and plasma levels; 5) FasL localization; and 6) alteration of the balance between Bax and Bcl-2. In addition, at the end of the observation period (7 days), zymosan causes severe illness in the mice characterized by a systemic toxicity, significant loss of body weight and mortality. Glutamine-treatment significantly reduced all these parameters.

Preconditioning with L-alanyl-glutamine reduces hepatic ischemia-reperfusion injury in rats

PURPOSE: To evaluate the effects of pre-conditioning with L-alanyl- glutamine (L-Ala-Gln) in rats subjected to total hepatic ischemia. METHODS: Thirty Wistar rats, average weight 300g, were randomly assigned to 3 groups (n=10): G-1 - Saline, G-2- L-Ala-Gln, G-3-control (Sham). G-1 and G-3 groups were treated with saline 2.0 ml or L-Ala-Gln (0.75mg/Kg) intraperitoneally (ip) respectively, 2 hours before laparotomy. Anesthetized rats were subjected to laparotomy and total hepatic ischemia (30 minutes) induced by by clamping of portal triad. Control group underwent peritoneal puncture, two hours before the sham operation (laparotomy only). At the end of ischemia (G1 and G2), the liver was reperfused for 60 minutes. Following reperfusion blood samples were collected for evaluation of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels. Liver (medium lobe) was removed for immunohistochemistry study with antibody for Caspase-3. RESULTS: It was found a significant decrease (p<0.05) of ALT levels (270.6 +40.8 vs 83.3 +5.5 - p <0.05), LDH (2079.0 +262.4 vs. 206.6 +16.2 - p <0.05) and Caspase-3 expression (6.72 +1.35 vs. 2.19 +1.14, p <0.05) in rats subjected to I / R, comparing the group treated with L-Ala -Gln with G-2. Also, the ALT level was significantly lower (P<0.05) in G-1 and G-2 groups than in G-3 (control group). CONCLUSION: L-Ala-Gln preconditioning in rats submitted to hepatic I/R significantly reduces ALT, LDH and Caspase-3 expression, suggesting hepatic protection.

Effect of preconditioned hyperbaric oxygen and ozone on ischemia-reperfusion induced tourniquet in skeletal bone of rats

BACKGROUND

The aim of the study was to investigate effect of I/R injury on bone tissue and protective role of hyperbaric oxygen precondition (HBO-PC) and ozone precondition (O(3)-PC) on I/R injury by using biochemical analysis.

MATERIALS AND METHODS

Thirty-two rats were included in study. The animals were divided into four equal groups: sham operation, I/R, I/R+HBO and I/R+O(3). One session of 60 min, 3 ATA, 3-4 L/min, 100% oxygenation was defined as one dose of HBO. First dose of HBO was administrated 72 h before ischemia. Subsequent, one-dose of HBO administrated per 12 hours until ischemia time (total seven doses); 0.7 mg/kg ozone/oxygen mixture intraperitoneally was defined as one dose of ozone. First dose of O(3) was administered 72 h before ischemia (total four doses). I/R model was induced in anesthetized rats by unilateral (right) femoral artery clipping for 2 h followed by 22 h of reperfusion. The right tibia and were harvested. Tissue was assayed for levels of malondialdehyde (MDA) and protein carbonyl (PCO), activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px).

RESULTS

MDA and PCO levels were increased in I/R group. SOD activity was increased; GSH-Px activity was decreased in I/R group. MDA and PCO levels were decreased, SOD and GSH-Px activities were increased in both HBO+I/R and O(3)+I/R groups.

CONCLUSION

It has been shown that levels of MDA and PCO in bone were increased followed by 2 h of ischemia and 22 h of reperfusion period. Ozone-PC and HBO-PC has protective effect against skeletal bone I/R injury by decreasing levels of MDA and PCO, increasing activities of SOD and GSH-Px in rats.

Glutamine preserves skeletal muscle force during an inflammatory insult

The purpose of this study was to test the hypothesis that acute glutamine (GLN) supplementation can counteract skeletal muscle contractile dysfunction occurring in response to inflammation by elevating muscle heat shock protein (Hsp) expression and reducing inflammatory cytokines. Mice received 5 mg/kg lipopolysaccharide (LPS) concurrently with 1 g/kg GLN or vehicle treatments. Plantarflexor isometric force production was measured at 2 hours post-injection. Blood and gastrocnemius muscles were collected, and serum and muscle tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) and muscle Hsp70 and Hsp25 were quantified. Saline/LPS treatment was associated with a 33% reduction in maximal force and elevated serum TNF-alpha and IL-6. GLN completely prevented this force decrement with LPS. GLN was found to reduce muscle Hsp70 and IL-6, but only in the presence of LPS. GLN supplementation provides an effective, novel, clinically applicable means of preserving muscle force during acute inflammation. These data indicate that force preservation is not dependent on reductions in serum cytokines or muscle TNF-alpha, or elevated Hsp levels.

The role of nitric oxide synthase and heme oxygenase in the protective effect of hypothermia in ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion injury plays an important role in limb salvage following limb ischemia. The purpose of the present study was to evaluate the effect of local hypothermia and chemical modulators on microvascular permeability following ischemia-reperfusion injury in skeletal muscle.

METHODS

Sprague-Dawley rats were randomized into nine groups. Postcapillary venules of the extensor digitorum longus muscle were visualized with use of intravital microscopy. Following an intravenous bolus of fluorescein isothiocyanate-labeled albumin, the intravascular and extravascular space was examined for leak. Rats in the sham group underwent a one-hour mock ischemic period without the application of a femoral artery tourniquet, followed by one hour of mock reperfusion. The treatment groups (n = 5 in each group) had the tourniquet applied for one hour, followed by one hour of reperfusion at 10 degrees C (cold) alone, at 10 degrees C with nitric oxide synthase inhibitor, at 10 degrees C with heme oxygenase inhibitor, at 10 degrees C with a combination of inhibitors, at 34 degrees C (warm) alone, at 34 degrees C with a heme oxygenase inducer, at 34 degrees C with a nitric oxide synthase inducer, or at 34 degrees C with a combination of inducers.

RESULTS

Rats in the sham group did not show a significant increase in microvascular permeability. Rats in the warm ischemia/reperfusion group displayed significant increases in microvascular permeability, as did the rats that received inhibitors of heme oxygenase and nitric oxide synthase at 10 degrees C. No significant increase in microvascular permeability was observed in the animals in the cold ischemia/reperfusion group or in animals that received inducers of heme oxygenase and nitric oxide synthase at 34 degrees C.

CONCLUSIONS

Local hypothermia protects skeletal muscle from increased microvascular permeability following ischemia-reperfusion injury. This protective effect is also seen with the induction of the nitric oxide synthase and heme oxygenase systems at physiologic temperature. We also have shown that the protective effects of hypothermia are blocked by giving heme oxygenase and nitric oxide synthase inhibitors while keeping the muscle hypothermic. These findings demonstrate that heme oxygenase and nitric oxide synthase play a combined role in ischemia-reperfusion injury, suggesting possible pathways for clinical intervention to modulate injury seen following trauma, tourniquet use, vascular surgery, and microvascular surgery.

Dexmedetomidine reduces the ischemia-reperfusion injury markers during upper extremity surgery with tourniquet

PURPOSE

We examined the effect of dexmedetomidine on ischemia-reperfusion injury due to tourniquet application during upper-extremity surgery by determining blood malondialdehyde and hypoxanthine levels. Alterations in aspartate aminotransferase, alanine aminotransferase, creatine phosphokinase, lactate dehydrogenase, uric acid, and creatinine levels were also assessed.

METHODS

Forty patients of American Society of Anesthesiologists physical status I to II having hand and forearm surgery with tourniquet were randomly allocated into 2 groups. Brachial plexus anesthesia via axillary approach was performed for upper-limb block in all patients. In the dexmedetomidine group, a continuous infusion of dexmedetomidine (1 microg/kg for 10 minutes, followed by 0.5 microg kg(-1) h(-1)) was used until the end of surgery, whereas the control group received an equivalent volume of saline. Venous blood samples were obtained before brachial plexus anesthesia, at 1 minute before tourniquet release, and 15 minutes after tourniquet release for biochemical analysis.

RESULTS

Dexmedetomidine significantly attenuated plasma hypoxanthine production in the ischemia and plasma malondialdehyde production in the reperfusion periods. Blood creatine phosphokinase and uric acid levels were significantly lower in the dexmedetomidine group compared with those in the control group after reperfusion.

CONCLUSIONS

Our results suggest that dexmedetomidine may offer advantages by inhibiting lipid peroxidation in the case of anticipated ischemia-reperfusion injury, such as would occur in upper-extremity surgery requiring tourniquet application.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

FTY720 Improves Survival After Transient Ischemia and Reperfusion of the Hind Limbs

BACKGROUND

Ischemia and reperfusion (I/R) damage involves adhesion and transmigration of lymphocytes and neutrophils. FTY720 is an immunosuppressive agent that reduces the number of neutrophils and monocytes in peripheral blood as well as tissue lymphocyte infiltration. This study investigated the effect of FTY720 during hind limb I/R.

METHODS

Male C57/BL6 mice underwent temporary ligation of the infrarenal aorta for 4 hours. After 48 hours of reperfusion, animals were killed by exsanguination. Tissue myeloperoxidase content reflecting neutrophil infiltration and reverse transcription polymerase chain reaction analysis of local cytokine transcription in lung, liver, and kidney were performed.

RESULTS

After I/R, treatment with FTY720 improved survival and prevented upregulation of pro- and anti-inflammatory cytokines in evaluated organs, whereas no changes were detected in myeloperoxidase content after treatment with FTY720.

CONCLUSIONS

Whereas neutrophil infiltration was not affected by treatment with FTY720, other immunocompetent or intrinsic cells appear to be involved in changes of cytokine production in different organs.

Simvastatin pretreatment reduces the severity of limb ischemia in an experimental diabetes model

OBJECTIVE

The purpose of this study was to examine the effects of simvastatin pretreatment in the setting of acute limb ischemia-reperfusion injury in an experimental diabetes model that is associated with a high risk for limb loss.

METHODS

Adult male Sprague-Dawley rats were randomized into two groups. Diabetes was induced in the first group by intravenous streptozotocin injection. The second group served as the nondiabetic group. Eight weeks after the streptozotocin injection, half of the rats in the diabetic and the nondiabetic groups were further randomized to receive either intraperitoneal simvastatin (1 mg/kg per day) or saline treatment for 6 weeks. Bilateral hind-limb ischemia was induced for 4 hours by the tourniquet method. After 24 hours of reperfusion, tissue samples were collected from the gastrocnemius and anterior tibial muscles bilaterally for measurement of muscle edema, percentage of necrosis, and malondialdehyde (MDA), glutathione, and myeloperoxidase (MPO) levels.

RESULTS

Ischemic injury was more prominent in diabetic animals. The diabetic animals with limb ischemia exhibited a 7% increase in tissue edema, a 47% increase in muscle necrosis and MPO level, and a 15% reduction in glutathione levels compared with the nondiabetic animals (P < .05). Simvastatin treatment with 1 mg/kg for 6 weeks reduced the ischemic injury. Simvastatin pretreatment led to a 71% reduction in muscle necrosis in diabetic animals (P < .001). The protective effects of simvastatin pretreatment also correlated with a 23% improvement in tissue edema, a 75% reduction in tissue myeloperoxidase content, and a 71% increase in glutathione levels in diabetic animals (P < .01). Furthermore, skeletal muscle injury, characterized by tissue edema and leucosequestration, was significantly less severe with simvastatin pretreatment compared with the nondiabetic animals (P < .01).

CONCLUSION

Simvastatin pretreatment reduced limb ischemia-reperfusion injury in diabetic and nondiabetic animals. We conclude that simvastatin pretreatment may be a potential therapeutic intervention for skeletal muscle ischemia-reperfusion injury in the clinical setting.

Dose-related effects of recombinant human interleukin-10 on hypoxia-induced skeletal muscle injury in immature rats

BACKGROUND

The role of cytokines in the pathogenesis of skeletal muscle injury in patients with hypoxia and inflammation remains unclear. The aim of the present study was to determine the dose-related effects of recombinant human interleukin-10 (rhIL-10) on hypoxia-induced skeletal muscle injury in immature rats.

METHODS

The study was performed on 1-day-old Sprague-Dawley rat pups that were randomized to one of five groups: nonhypoxic controls (group 1; n=8); rats subjected to hypoxia-reoxygenation (H/O) and returned to their mothers (group 2; n=11); rats subjected to H/O, returned to their mothers, and treated with rhIL-10 (10 microg/kg per day s.c.) for 3 days (group 3; n=10); rats subjected to H/O, returned to their mothers, and treated with rhIL-10 (25 microg/kg per day s.c.) for 3 days (group 4; n=10); or rats subjected to H/O, returned to their mothers, and treated with rhIL-10 (75 microg/kg per day s.c.) for 3 days (group 5; n=10). All animals were killed on day 4, and skeletal muscle specimens were obtained to determine the tissue levels of malondialdehyde (MDA) and superoxide dismutase (SOD) and to check for any histological changes.

RESULTS

The polymorphonuclear leukocyte count, amount of interstitial edema, microvessel size, and area of myocyte necrosis was greater in groups 2, 3, 4, and 5 than in group 1, although the findings were significantly less prominent in groups 4 and 5 than in groups 2 and 3. MDA levels significantly increased in groups 2 and 3 compared to those in groups 1, 4, and 5. SOD values decreased significantly in groups 2 and 3 compared to those in groups 1, 4, and 5.

CONCLUSIONS

Administration of rhIL-10 reduced skeletal muscle injury produced by hypoxia in immature rats. Intermediate and high doses of rhIL-10 were associated with a significant reduction of skeletal muscle damage, whereas a low dose was not.

Protective effects of caffeic acid phenethyl ester on skeletal muscle ischemia-reperfusion injury in rats

There is a great evidence that reactive oxygen species (ROS) play an important role in the pathophysiology of ischemia-reperfusion (I/R) injury in skeletal muscle. Caffeic acid phenethyl ester (CAPE) is a component of honeybee propolis. It has antioxidant, anti-inflammatory and free radical scavenger properties. The aim of this study is to determine the protective effects of CAPE against I/R injury in respect of protein oxidation, neutrophil in filtration, and the activities of xanthine oxidase (XO) and adenosine deaminase (AD) on an in vivo model of skeletal muscle I/R injury. Rats were divided into three equal groups each consisting of six rats: Sham operation, I/R, and I/R plus CAPE (I/R+CAPE) groups. CAPE was administered intraperitoneally 60 min before the beginning of the reperfusion. At the end of experimental procedure, blood and gastrocnemius muscle tissues were used for biochemical analyses. Tissue protein carbonyl (PC) levels and the activities of XO, myeloperoxidase (MPO) and AD in I/R group were significantly higher than that of control (p < 0.01, p < 0.05, p < 0.01, p < 0.005, respectively). Administration of CAPE significantly decreased tissue PC levels, MPO and XO activities in skeletal muscle compared to I/R group (p < 0.01, p < 0.05, p < 0.05, respectively). In addition, plasma creatine phosphokinase (CPK), XO and AD activities were decreased in I/R+CAPE group compared to I/R group (p < 0.05, p < 0.05, p < 0.001). The results of this study revealed that free radical attacks may play an important role in the pathogenesis of skeletal muscle I/R injury. Also, the potent free radical scavenger compound, CAPE, may have protective potential in this process. Therefore, it can be speculated that CAPE or other antioxidant agents may be useful in the treatment of I/R injury as well as diffused traumatic injury of skeletal muscle.

Does propofol or caffeic acid phenethyl ester prevent lung injury after hindlimb ischaemia-reperfusion in ventilated rats?

BACKGROUND

To investigate the effects of propofol and caffeic acid phenethyl ester (CAPE) on prevention of lung injury as a remote organ after performing hindlimb ischaemia-reperfusion (IR) in a rat model.

METHODS

The animals were divided randomly into one of four groups: sham, no IR (n = 8), control, IR, (n = 8), CAPE group, IR with CAPE, (n = 8), propofol group, IR with P, (n = 8). After the rats were anaesthetised, the animals in the CAPE group received CAPE of 10 micromol, in the propofol group received propofol 50 mg/kg, in the control group received a similar volume of saline solution by means of intraperitoneal injection 1 h before reperfusion. After 4 h of ischaemia the tourniquet was removed and the animals were released for reperfusion for 4 h thereafter. At the end of the reperfusion period, a median sternotomy was performed. A blood sample was obtained for plasma malondialdehyde (MDA). The lung tissues were also removed for MDA assays, myeloperoxidase (MPO) activity, and histopathological examination.

RESULTS

Plasma and lung MDA levels, and lung MPO activity were significantly higher in the control group compared to the other groups (p < 0.0005). In the CAPE group, these were significantly lower compared to the control group (p < 0.0005). Also, propofol caused a marked reduction in the MDA levels and MPO activity compared with control group (p < 0.0005), with no significant difference compared to that of the sham group. Histopathologically, the scores resulted in a grade zero (8/8) in the sham group, 3 (3/8) or 4 (5/8) in the control group, 1 (2/8) or 2 (6/8) in the CAPE group, and 1 (3/8) or 2 (5/8) in the propofol group.

CONCLUSION

Propofol and CAPE seem to be effective in protecting against lung injury caused by increased oxidative stress and neutrophil accumulation after hindlimb IR in a rat model.

Alanyl-glutamine dipeptide inhibits hepatic ischemia-reperfusion injury in rats

AIM: To investigate the protective effect and mechanism of alanyl-glutamine dipeptide (Ala-Gln) against hepatic ischemia-reperfusion injury in rats.

METHODS: Rats were divided into group C as normal control Group (n=16) and group G as alanyl-glutamine pretreatment (n=16). Rats were intravenously infused with 0.9% saline solution in group C and Ala-Gln -enriched (2% glutamine) 0.9% saline solution in group G via central venous catheter for three days. Then all rats underwent hepatic warm ischemia for 30 min followed by different periods of reperfusion. Changes in biochemical parameters, the content of glutathione (GSH) and the activity of superoxide dismutase (SOD) in liver tissue, Bcl-2 and Bax protein expression and morphological changes of liver tissue were compared between both groups.

RESULTS: One hour after reperfusion, the levels of liver enzymes in group G were significantly lower than those in group C (P<0.05). Twenty-four hours after reperfusion, the levels of liver enzymes in both groups were markedly recovered and the levels of liver enzyme in group G were also significantly lower than those in group C (P <0.01). One and 24 h after reperfusion, GSH content in group G was significantly higher than that in group C (P <0.05). There was no statistical difference in activities of SOD between the two groups. One and 24 h after reperfusion, the positive expression rate of Bcl-2 protein was higher in group G than in group C (P <0.05) and the positive expression rate of Bax protein was lower in group G than in group C (P < 0.05). Histological and ultrastructural changes of liver tissue were inhibited in group C compared to group G.

CONCLUSION: Our results suggest that Ala-Gln pretreatment provides the rat liver with significant tolerance to warm ischemia-reperfusion injury, which may be mediated partially by enhancing GSH content and regulating the expression of Bcl-2 and Bax proteins in the liver tissue.

Method of pyloric reconstruction and impact upon delayed gastric emptying and hospital stay after pylorus-preserving pancreaticoduodenectomy

Preservation of the pylorus at the time of pancreaticoduodenectomy has been associated with equal oncological outcomes when compared to the classical Whipple operation. Multiple studies have demonstrated that pylorus-preserving pancreaticoduodenectomy (PPPD) has equal or superior outcomes regarding quality of life when compared with the traditional Whipple operation, but many studies have suggested a higher incidence of delayed gastric emptying (DGE). DGE prolongs hospital stay, and its association with PPPD has hampered its adoption by many pancreatic surgery centers. We describe a novel surgical technique for the prevention of delayed gastric emptying following pylorus-preserving pancreaticoduodenectomy. The technique of pyloric dilatation appears to decrease the incidence of delayed gastric emptying and facilitates earlier hospital discharge, when compared with standard pylorus preserving pancreaticoduodenectomy.

The effect of ketamine on acute muscular ischaemia reperfusion in rats

BACKGROUND AND OBJECTIVE

The aim of this study was to investigate any possible protective effect of ketamine in acute muscular ischaemia and reperfusion injury by measuring malondialdehyde using thiobarbituric acid assay in rats.

METHODS

Twelve female Wistar albino rats were anaesthetized with chloral hydrate and randomly assigned into two groups to receive ketamine 1 mg kg(-1) min(-1) or saline infusion. Blood and gastrocnemius muscle samples were obtained 10 min after onset of infusion, before ischaemia. Then, femoral arteries were clamped for 30 min. Blood and muscle samples were obtained at the 30th minute of ischaemia and 10 min after reperfusion.

RESULTS

Muscle malondialdehyde concentrations were 27.88 +/- 2.45, 27.62 +/- 3.98 before ischaemia, 32.10 +/- 4.19, 30.77 +/- 2.73 in the 30th minute of ischaemia and 44.34 +/- 2.45, 34.83 +/- 2.78 after reperfusion in saline and ketamine-treated rats, respectively (nmol g(-1), mean +/- SD). The muscle malondialdehyde level after reperfusion was lower in ketamine-treated rats compared to saline group (P < 0.002). Plasma malondialdehyde levels were 3.77 +/- 0.16, 3.78 +/- 0.18 before ischaemia, 3.81 +/- 0.25, 4.00 +/- 0.86 at the 30th minute of ischaemia and 4.00 +/- 0.53, 3.94 +/- 0.95 after reperfusion, respectively, in saline and ketamine-treated rats (micromol L(-1), mean +/- SD). The effect of ketamine on muscular malondialdehyde was not observed in concurrent plasma malondialdehyde levels.

CONCLUSION

Ketamine was found to attenuate acute ischaemia-reperfusion injury in muscle tissue in rats (muscular protective). Ketamine may attenuate lipid peroxidation in muscle tissue in tourniquet-requiring manoeuvres.

Effects of glutamine on glutathione content and expression of Bcl-2 and Bax protein during hepatic ischemia and reperfusion injury in rats

AIM: To investigate the effect of alanyl-glutamine dipeptiven (Ala-Gln) on the content of glutathione (GSH) and the expression of Bcl-2 and Bax protein during hepatic ischemia and reperfusion injury (HIRI) in rats.

METHODS: A total of 48 Wistar rats were randomly divided into glutamine group (group G) and control group (group C), which were pretreated with Gln and normal saline, respectively. The liver was subjected to warm ischemia by Pringle method for 30 min, and then reperfused. The serum samples were colleted 1 and 24 h after the reperfusion, and the level of serum ALT was measured. The GSH content and histopathological changes were detected in the liver tissues. The expression of Bcl-2 and Bax protein in the liver tissues were detected by immunohistochemistry.

RESULTS: The level of serum ALT was significantly lower in group G than that in group C 1 and 24 h after the reperfusion (8.3 ± 2.0 mkat/L vs 13.7± 5.5 mkat/L, P < 0.05; 2.9 ± 2.5 mkat/L vs 9.1 ± 4.3 mkat/L, P < 0.01), but the GSH content was significantly higher in group G than that in group C (1216.09 ± 152.78 mg/g vs 856.68 ± 117.64 mg/g, P < 0.01; 899.73 ± 57.75 mg/g vs 800.50 ± 94.79 mg/g, P < 0.05). The histopathological changes were significantly slighter in group G than those in group C. One and twenty-four hours after the reperfusion, the positive rate of Bcl-2 protein expression was significantly higher in group G than that in group C (100.0% vs 37.5%, P < 0.05; 87.5% vs 25.0%, P < 0.05), while the positive rate of Bax protein expression was significantly lower in group G than that in group C (25.0% vs 87.5%, P < 0.05; 25.0% vs 87.5%, P < 0.05).

CONCLUSION: Ala-Gln (Gln) can protect rats against HIRI, and the mechanism may relate to the enhancement of GSH content and the regulation of Bcl-2, Bax protein expression.

Ketamine Sedation During Spinal Anesthesia for Arthroscopic Knee Surgery Reduced the Ischemia-Reperfusion Injury Markers

We studied the effect of ketamine sedation on oxidative stress during arthroscopic knee surgery with tourniquet application by determining blood and tissue malonyldialdehyde (MDA) and hypoxanthine (HPX) levels. Thirty ASA I-II patients undergoing arthroscopic knee surgery with tourniquet were randomly divided into two groups. Spinal anesthesia induced with 12.5 mg bupivacaine was administered to all patients. In the ketamine group, after IV administration of 0.01 mg/kg midazolam, a continuous infusion of ketamine (0.5 mg . kg(-1) . h(-1)) was used until the end of surgery whereas the placebo group received a volume-equivalent placebo infusion. Ramsey Sedation Scale (RSS) was used for assessing the sedation level. Venous blood and synovial membrane tissue samples were obtained before ketamine infusion, at 30 min of tourniquet ischemia, and at 5 min after tourniquet deflation for MDA and HPX measurements. Tissue MDA and HPX levels were significantly less in the ketamine group than the control group after reperfusion. RSS scores were higher in the ketamine group without any adverse effect. We conclude that ketamine sedation attenuates lipid peroxidation markers in arthroscopic knee surgery with tourniquet application.

Effect of low-dose N-acetyl-cysteine infusion on tourniquet-induced ischaemia-reperfusion injury in arthroscopic knee surgery

BACKGROUND

Temporary occlusion of blood flow is used during arthroscopic knee surgery in order to provide a bloodless surgical field. The resulting ischaemia-reperfusion causes lipid peroxidation, which contributes to tissue injury. The aim of the study was to investigate the effect of low-dose n-acetyl cysteine (NAC) infusion on oxidative stress by determining malondialdehyde (MDA) levels during arthroscopic knee surgery.

METHODS

Thirty patients, ASA I - II, undergoing arthroscopic knee debridement under a tourniquet were divided into NAC and control groups. Anaesthesia was induced with propofol, fentanyl and vecuronium bromide and maintained with desflurane in an equal parts O(2)-N(2)O mixture. In the NAC group, an infusion of NAC, 5 mg kg(-1).h(-1), was started after intubation, and continued until extubation. An equal volume of saline was infused to the control group. Duration of ischaemia, anaesthesia time, total dose of NAC infused were also recorded. Venous blood and synovial membrane tissue samples were obtained 10 min after the onset of NAC infusion but before tourniquet inflation (t1), after 30 min of ischaemia (t2), and after 5 min of reperfusion following tourniquet release (t3).

RESULTS

Plasma MDA levels were significantly lower in the NAC group on reperfusion. There were no differences between the groups in tissue MDA levels at ischaemia and reperfusion times.

CONCLUSION

Low-dose n-acetyl cysteine infusion attenuates lipid peroxidation and ischaemia-reperfusion injury in arthroscopic knee surgery requiring tourniquet application.

Protective effects of clopidogrel on oxidant damage in a rat model of acute ischemia

Reperfusion injury is a consequence of inadequate energy supply and acidosis in ischemic tissues and a chain of events triggered by oxygen-derived free radicals released in response to exposure of oxygen. In this study, we aimed to assess the effects of clopidogrel, an antithrombotic agent, on experimental ischemia-reperfusion model in rats. The ischemia was performed by blockade of the circulation of right lower extremity at trochanter major level for 6 hours. Then, the extremity was reperfused for 4 hours. Another group of rats pretreated with clopidogrel (0.2 mg/kg/day) for 10 days prior to ischemia-reperfusion. After the reperfusion period, all rats were anesthetized with ketamine. Blood and tissue samples from the gastrocnemius muscle, liver and lungs were taken for the measurement of malondialdehyde (MDA), glutathione (GSH) levels and superoxide dismutase (SOD) activity. The results revealed that clopidogrel prevented the increase in MDA level and the decrease in GSH level and SOD activity caused by ischemia-reperfusion both in tissue samples and plasma. These findings suggest that clopidogrel is beneficial in prevention of ischemia-reperfusion injury probably via its effects on inflammatory cells, platelets, and endothelial cells.

Aprotinin ameliorates ischemia/reperfusion injury in a rat hind limb model

The aim of the study was to investigate the protective effect of aprotinin in a rat hind limb ischemia/reperfusion (I/R) model. A well-known antioxidant, alpha-tocopherol, was also tested for comparison. Ischemia was induced for 4 h by vascular clamping of the iliac arteries of 24 Sprague-Dawley rats, followed by 1 h of reperfusion. Muscle injury was evaluated in three groups: a saline group, an alpha-tocopherol group and an aprotinin group. Blood pH, pO2, pCO2, HCO3, creatine kinase (CPK), lactate dehyrogenase (LDH) and thiobarbituric acid reactive substances (TBARS) as well as muscle TBARS were measured at the end of the reperfusion. Muscle tissue samples were taken for histological examination. alpha-Tocopherol and aprotinin groups showed a significant amelioration of plasma CPK (p=0.002, p=0.002), LDH (p=0.004, p=0.004) and muscle tissue TBARS (p=0.001, p=0.001) compared with the control. Plasma TBARS were significantly lower in the aprotinin group compared with the control (p=0.017). Also, tissue TBARS was significantly lower in the aprotinin group than the alpha-tocopherol group (p<0.001). Neutrophil infiltration was less prominent in the alpha-tocopherol and aprotinin groups compared to the control (p=0.006, p=0.001). These results suggest that aprotinin, a potent anti-inflammatory drug, is more useful than alpha-tocopherol, a powerful antioxidant, for attenuating muscle injury after I/R.

Use of tissue ultrafiltration for treatment of compartment syndrome: a pilot study using porcine hindlimbs

OBJECTIVES

To demonstrate the efficacy of compartment syndrome ultrafiltration for the treatment of acute compartment syndrome in an animal model. Our hypothesis is the removal of interstitial fluid will result in a reduction of intramuscular pressure compared with untreated controls in a model of bilateral induced compartment syndrome.

DESIGN

Controlled experimental model.

SETTING

Animal research facility.

PATIENTS/PARTICIPANTS

Three pairs of porcine hindlimbs.

INTERVENTION

Acute compartment syndrome was created in the pig hindlimb by infusion of saline to maintain the intramuscular pressure 30 mm Hg greater than the animal's mean arterial pressure for 8 hours. After a 2-hour reperfusion interval, ultrafiltration (removal of fluid through 1 mm diameter porous catheters, connected to -500 mm Hg suction) was commenced in 1 limb only and continued for 9.5 hours.

MAIN OUTCOME MEASURES

Intramuscular pressure, ultrafiltrate volume, ultrafiltrate and serum levels of creatine kinase and lactate dehydrogenase, histologic measurement of extracellular and intracellular edema, as well as the degree of cellular necrosis.

RESULTS

Intramuscular pressure tended to be lower on the treated side at the end of the treatment period [treated leg: 9.3 +/- 4.0 mm Hg (+/- SE), control leg: 19.3 +/- 1.4 mm Hg, P = 0.03]. Analysis of ultrafiltrate fluid showed that levels of creatine kinase and lactate dehydrogenase were elevated compared with serum levels. Creatine kinase levels in serum were measured at 4150 +/- 780 U/L, whereas ultrafiltrate levels of creatine kinase were 28,700 +/- 17,700 U/L (+/- SE) (P = 0.1). Lactate dehydrogenase was measured at 1950 +/- 180 U/L in serum, but markedly elevated in ultrafiltrate [160,000 +/- 88,900 U/L (+/- SE), P = 0.05]. Quantification of cellular and interstitial dimensions showed no difference in control and experimental limbs. Quantification of the degree of muscle necrosis revealed 6.1 +/- 2.7% necrosis in the treated limb compared to 11.3 +/- 1.6% necrosis in the control group (P = 0.02, df = 2, 1-tailed paired t test).

CONCLUSION

This pilot study demonstrates the feasibility of tissue ultrafiltration for reduction of intramuscular pressure in this porcine model. Further studies are underway. Compartment syndrome ultrafiltration may be useful prophylactically in patients at risk for acute compartment syndrome. Sampling of interstitial fluid and frequent measurement of intramuscular pressure may allow earlier diagnosis and treatment of acute compartment syndrome, whereas the reduction of tissue pressure by compartment syndrome ultrafiltration may prevent acute compartment syndrome from occurring. Additionally, compartment syndrome ultrafiltration will not hinder the ability of clinicians to use the clinical examination and pressure monitoring as the gold standard.

Surgical manipulation of the intestine and distant organ damage—protection by oral glutamine supplementation

BACKGROUND

The intestine is increasingly recognized as a primary effector of distant organ damage, such as the lung, after any abdominal surgery. Earlier studies have shown that surgical manipulation of the intestine induces generation of reactive oxygen species in the intestine, resulting in mucosal and lung damage. Because glutamine is preferentially used by the small intestine as an energy source, this study examined the effect of glutamine and glutamic acid on intestinal and lung damage after surgical manipulation.

METHODS

Controls and rats were pretreated for 7 days with 2% glutamine or glutamic acid, or the isonitrogenous amino acids glycine or alanine in the diet and subjected to surgical manipulation of the intestine. The intestine and lung were assessed for damage, and protection offered by various amino acids was studied.

RESULTS

Surgical manipulation resulted in oxidative stress in the intestine as evidenced by increased xanthine oxidase activity and decreased antioxidant status. Enterocyte mitochondria were also functionally impaired with altered calcium flux, decreased respiratory control ratio, and increased swelling. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by an increase in myeloperoxidase activity, lipid peroxidation, and antioxidant status. Glutamine or glutamic acid supplementation for 7 days before surgical manipulation showed a protective effect against the intestinal and lung damage.

CONCLUSIONS

This study suggests that preoperative enteral glutamine or glutamic acid supplementation attenuates intestinal and lung damage in rats during surgical manipulation and that this effect might offer protection from postsurgical complications.

N/A

N/A

Antioxidant effect of MCI-186, a new Free-Radical scavenger, on ischemia-reperfusion injury in a rat hindlimb amputation model

BACKGROUND

A newly synthesized free-radical scavenger, MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-1), was recently approved in Japan for treating acute brain infarction. The purpose of this study was to investigate whether or not MCI-186 is effective in reducing ischemia-reperfusion injury in the extremities.

MATERIALS AND METHODS

Warm ischemia was sustained for 4 hours. The animals were divided into 4 groups: (1) sham group, (2) control group (saline injection), (3) MCI group (MCI-186 injection), and (4) EPC group (EPC-K1 [(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], a hydroxyl-radical scavenger, injection). Wet and dry (W/D) weights of the gastrocnemius and tibialis anterior muscles, muscle contractile function, and serum levels of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), glutamic oxaloacetic transminase (GOT), and mitochondrial glutamic oxaloacetic transminase (GOT-m) were measured after 24 h of reperfusion. The cytotoxic aldehydes malondialdehyde and 4-hydroxy-2-nonenal as indices of lipid peroxidation (LPO), and neutrophil-specific enzyme myeloperoxidase (MPO) as an index of neutrophil infiltration, were measured in the gastrocnemius muscle.

RESULTS

Contractile functions in the MCI and EPC groups were significantly better than in the control group. In the tibialis anterior muscle, the contractile function was better in the MCI group than in the EPC group. W/D ratios and serum levels of CPK, LDH, GOT, and GOT-m were lower in the sham and MCI groups than in the control group. Levels of LPO and MPO activity were significantly lower in the MCI and EPC groups than in the control group. Histological findings demonstrated that inflammatory tissue reactions rarely occurred in the MCI group.

CONCLUSION

MCI-186 is effective in preventing ischemia-reperfusion injury in extremities. MCI-186 seems to have promise as a therapeutic agent, because it prevents ischemia-reperfusion injury even in the tibialis anterior muscle, which contains fast-twitch glycolytic fibers, known to be very susceptible to ischemic insult.

Role of intestine in postsurgical complications: involvement of free radicals

Surgery at any location in the body leads to surgical stress response and alterations in normal body homeostasis. The intestine is extremely sensitive to surgical stress even at remote locations and the gastrointestinal tract plays an important role in the development of postsurgical complications such as sepsis, the systemic immune response syndrome (SIRS), and multiple organ failure syndrome (MOFS). The generation of free radicals and subsequent biochemical alterations at the cellular and subcellular level in the intestine has been suggested to play an important role in this process. These oxidative stress-induced events in the mucosa might act as an initiator of distant organ damage and also facilitate bacterial adherence onto the epithelium and translocation into the systemic circulation. This review attempts to highlight the important role of intestine and oxygen free radicals in initiating post-surgical complications.

Oxidative stress and heat shock protein response in human paraspinal muscles during retraction

OBJECT

The need for wide dissection and forceful retraction of paraspinal muscles often required for posterolateral lumbar fusion and fixation may severely jeopardize the muscles, structurally and functionally. The underlying pathophysiology of muscle damage may involve both mechanical and ischemic mechanisms. On the other hand, the surgery-related stress may trigger certain protective responses within the insulted paraspinal muscles. This study was conducted to assess the relationship between the oxidative stress and the stress response mediated by heat shock protein 70 (HSP70) induction within paraspinal muscles being retracted.

METHODS

Multifidus muscle specimens were surgically obtained before, during, and after retraction in patients with lumbar spondylolisthesis undergoing posterolateral lumbar fusion, pedicle fixation, and laminectomy. Muscle samples were analyzed to determine HSP70 and malondialdehyde (MDA) levels. Both HSP70 expression and MDA production within multifidus muscle cells were increased significantly by retraction. Expression of HSP70 then decreased after a peak at 1.5 hours of retraction, whereas MDA levels remained elevated even after release of retractors for reperfusion of the muscles. Analysis of histopathological and immunohistochemical evidence indicated that the decline of HSP70 synthesis within muscle cells after prolonged retraction was the result of severe muscle damage.

CONCLUSIONS

Results of this study highlight the deleterious effect of intraoperative retraction on human paraspinal muscles at the cellular and molecular levels. The authors also found that intraoperative maneuvers aimed at reducing the oxidative stress within the paraspinal muscles may help to attenuate surgery-related paraspinal muscle damage.

Glutamine and its relationship with intracellular redox status, oxidative stress and cell proliferation/death

Glutamine is a multifaceted amino acid used for hepatic urea synthesis, renal ammoniagenesis, gluconeogenesis in both liver and kidney, and as a major respiratory fuel for many cells. Decreased glutamine concentrations are found during catabolic stress and are related to susceptibility to infections. Besides, glutamine is not only an important energy source in mitochondria, but is also a precursor of the brain neurotransmitter glutamate, which is likewise used for biosynthesis of the cellular antioxidant glutathione. Reactive oxygen species, such as superoxide anions and hydrogen peroxide, function as intracellular second messengers activating, among others, apoptosis, whereas glutamine is an apoptosis suppressor. In fact, it could contribute to block apoptosis induced by exogenous agents or by intracellular stimuli. In conclusion, this article shows evidences for the important role of glutamine in the regulation of the cellular redox balance, including brain oxidative metabolism, apoptosis and tumour cell proliferation.

Skeletal muscle ischaemia-reperfusion injury: further characterisation of a rodent model

BACKGROUND

Postischaemic damage in skeletal muscle may be reflected in changes to microvascular blood flow, vascular permeability, and subsequent tissue viability. Previous preclinical studies have not addressed all these parameters, and have not used periods of ischaemia and reperfusion relevant to the clinical setting. This study aimed to develop an animal model hindlimb ischaemia-reperfusion to simulate acute lower limb ischaemia.

METHODS

A rodent model of hindlimb tourniquet-induced ischaemia-reperfusion was employed. Gastrocnemius muscle blood flow (GMBF; radio-labelled microspheres), oedema (GMO; using a wet:dry ratio method) and viability (GMV; histochemistry and computerised planimetry) were quantified.

RESULTS

6 h ischaemia per seresulted in neither muscle oedema nor loss of viability, but these changes were apparent following 4 h reperfusion. Early reperfusion at 10 min demonstrated low reflow, with GMBF improving at 120 min before declining sharply at 240 min.

CONCLUSION

Prolonged hindlimb ischaemia followed by reperfusion in this rodent model caused significant reductions in gastrocnemius muscle blood flow, associated with muscle oedema and necrosis. These three parameters have not been previously reported together in the same model. This reproducible model could be used in the evaluation of potential therapeutic intervention strategies aimed at ameliorating skeletal muscle reperfusion injury.