In situ determination by surface chemiluminescence of temporal relationships between evolving warm ischemia-reperfusion injury in rat liver and phagocyte activation and recruitment

Co-administration of Salvia miltiorrhiza and verapamil inhibits detrimental effects of torsion/detorsion on testicular tissue in rats

Testicular torsion/detorsion is one of the important emergencies that requires fast surgical intervention. This study aimed to investigate the effects of Salvia miltiorrhiza hydroalcoholic extract combined with verapamil on testicular ischaemia/reperfusion damage in Wistar albino rats. All animals were distributed in 3 groups (n = 8), including the sham-operated group, torsion/detorsion (TD) group and torsion/detorsion + pretreatment with 200 mg/kg Salvia miltiorrhiza extract combined with 0.3 mg/kg verapamil (SMV) group. Oxidative stress biomarkers (MDA, GPx, CAT and TAC) both in plasma and testicular tissue, sperm parameters (motility, vitality, concentration and morphology) and histopathological parameters (MSTD, GECT, Johnson's score, Cosentino's score and testicular cell thickness) were assessed in all groups. Ischaemia/reperfusion significantly increased MDA and decreased GPx, CAT and TAC levels (p < .05). Pretreatment with SMV significantly increased GPx, CAT and TAC levels (p < .05). SMV group increased progressive sperm motility and vitality and reduced non-progressive motility of spermatozoon (p < .05). Testicular torsion significantly decreased all histopathological parameters compared to the sham group (p < .05). SMV pretreatment remarkably increased MSTD, GECT and Cosentino's score in comparison with the TD group (p < .05). A combination of Salvia miltiorrhiza with verapamil could reduce damages triggered by testicular torsion detorsion and improve sperm functionality parameters and oxidative stress defence systems.

Protective effect of dipeptidyl peptidase-4 inhibitors in testicular torsion/detorsion in rats: a possible role of HIF-1α and nitric oxide

Spermatic cord torsion is a serious and common urologic emergency. It requires early diagnosis for prevention of subfertility and testicular necrosis. Vildagliptin and sitagliptin are anti-diabetic drugs of the dipeptidyl peptidase-4 (DPP-4) inhibitors that have a protective role against cerebral ischemic stroke and cardiac ischemia reperfusion. This study aimed to investigate the role and mechanism of action of vildagliptin and sitagliptin in a model of testicular ischemia/reperfusion injury by testicular torsion/detorsion (T/D). Testicular T/D was done and vildagliptin and sitagliptin were administered either alone or in combination with nitric oxide synthase (NOS) inhibitor. Serum total cholesterol and testosterone were measured, while in testicular tissue testosterone, malondialdehyde (MDA) level, total antioxidant capacity (TAC), nitric oxide level, caspase-3, superoxide dismutase (SOD), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α) and endothelial NOS (eNOS), and inducible NOS (iNOS) and neuronal NOS (nNOS) were measured. Histopathology of testicular tissue was done. Vildagliptin and sitagliptin increased serum testosterone, expression, and activity of SOD and testicular TAC. It also reduced total serum cholesterol, testicular MDA, caspase-3, HIF-1α, TNF-α, and expression of eNOS, iNOS, and nNOS. Vildagliptin and sitagliptin also improved histopathological picture of testicular tissue. NOS inhibitor produced similar result to DDP-4 inhibitors; however, its co-administration augmented the effect of vildagliptin and sitagliptin on these parameters. DPP-4 inhibitors, vildagliptin, and sitagliptin were protective against testicular T/D-induced injury mostly by anti-oxidative stress, and anti-apoptotic and anti-inflammatory actions that was augmented by NOS inhibition with a possible role for HIF-1α expression.

Redox dyshomeostasis in the experimental chronic hepatic overloads with iron or copper

Male rats of 80-90 g were overloaded with either Fe(II) or Cu(II) for 42 days by high concentrations of FeCl₂ or CuSO₄ in the drinking water. The animals were fed with a commercial rodent diet of 2780 kcal/100 g. Both metal treatments led to a liver redox imbalance and dyshomeostasis with oxidative stress and damage and the concomitant enhancement of oxidative processes as indicated by in vivo surface liver chemiluminescence, the sensitive and organ non-invasive assay for oxidative free radical reactions, and by ex vivo determined processes of phospholipid peroxidation and protein oxidation. In parallel, marked decreases in the antioxidant defense were observed. Liver reduced glutathione (GSH) content and the reduced/oxidized glutathione ratio (GSH/GSSG) were early indicators of oxidative metabolic disturbance upon the metal overloads. Thus, GSH plays a central role in the defense reactions involved in the chronic toxicity of Fe and Cu. Chronic overloads of Fe or Cu in rats afford an experimental animal model of hemochromatosis and of Wilson's disease, respectively. These two animal models could be useful in the study and development of the beneficial effects of pharmacological interventions in the two human diseases.

The Contribution of Singlet Oxygen to Insulin Resistance

Insulin resistance contributes to the development of diabetes and cardiovascular dysfunctions. Recent studies showed that elevated singlet oxygen-mediated lipid peroxidation precedes and predicts diet-induced insulin resistance (IR), and neutrophils were suggested to be responsible for such singlet oxygen production. This review highlights literature suggesting that insulin-responsive cells such as endothelial cells, hepatocytes, adipocytes, and myocytes also produce singlet oxygen, which contributes to insulin resistance, for example, by generating bioactive aldehydes, inducing endoplasmic reticulum (ER) stress, and modifying mitochondrial DNA. In these cells, nutrient overload leads to the activation of Toll-like receptor 4 and other receptors, leading to the production of both peroxynitrite and hydrogen peroxide, which react to produce singlet oxygen. Cytochrome P450 2E1 and cytochrome c also contribute to singlet oxygen formation in the ER and mitochondria, respectively. Endothelial cell-derived singlet oxygen is suggested to mediate the formation of oxidized low-density lipoprotein which perpetuates IR, partly through neutrophil recruitment to adipose tissue. New singlet oxygen-involving pathways for the formation of IR-inducing bioactive aldehydes such as 4-hydroperoxy-(or hydroxy or oxo)-2-nonenal, malondialdehyde, and cholesterol secosterol A are proposed. Strategies against IR should target the singlet oxygen-producing pathways, singlet oxygen quenching, and singlet oxygen-induced cellular responses.

Topical Application of Mesenchymal Stromal Cells Ameliorated Liver Parenchyma Damage After Ischemia-Reperfusion Injury in an Animal Model

Supplemental digital content is available in the text.

Background

Ischemia-reperfusion injury (IRI) is commonly encountered after liver surgery. This study evaluated the hepatoprotective effects of topically applied adipose-derived mesenchymal stromal cells (ADMSCs) on hepatic IRI in a rat model.

Methods

ADMSCs from transgenic green fluorescent protein Sprague-Dawley rats were topically applied to the liver surface of Sprague-Dawley rats after hepatic IRI and fixed in position by fibrin glue (group A, n = 24). An equivalent amount of ADMSCs were administered through the portal (group B, n = 24) or tail vein (group C, n = 24). In the control group (group D, n = 20), no treatment was given to the IRI liver.

Results

All the rats in group A and group D survived. Within 2 days after hepatic IRI, only 50% of rats survived in group B, and ADMSCs were detected in thromboemboli within large vessels. 62.5% of the rats died in group C because most of the ADMSCs were trapped in the lungs. ADMSCs migrated across the liver capsule and homed to the injured liver parenchyma 3 days after topical application in group A. The homed ADMSCs expressed hepatocyte nuclear factor-4α and hepatocyte nuclear factor-1. Compared with group D, the rate of hepatic regeneration in group A was enhanced with less inflammation, smaller necrotic areas, and improved liver function. Proinflammatory cytokines IL-6, IL-21, and CD70 were significantly downregulated in group A by 6.3-, 2.7-, and 12.7-fold, respectively (P < 0.05). The neurogenic locus NOTCH homolog protein pathway was activated in the topical ADMSCs.

Conclusions

Topically applied adipose-derived mesenchymal stromal cells demonstrated hepatoprotective effects on hepatic IRI in an animal model.

Neutrophil Recruitment in the Reperfused-Injured Rat Liver was Effectively Attenuated by Repertaxin, a Novel Allosteric Noncompetitive Inhibitor of Cxcl8 Receptors: A Therapeutic Approach for the Treatment of Post-Ischemic Hepatic Syndromes

Hepatic reperfusion injury represents a crucial problem in several clinical situations including liver transplantation, extensive hepatectomy and hypovolemic shock with resuscitation. Repertaxin is a new non-competive allosteric blocker of interleukin-8 (CXCL8) receptors, which by locking CXCR1/R2 in an inactive conformation, prevents receptor signaling and polymorphonuclear leukocyte (PMN) Chemotaxis. The present study shows that repertaxin dramatically prevents rat post-ischemic hepatocellular necrosis (80% of inhibition) and PMN infiltration (96% of inhibition) at a clinically-relevant time (24 h) of reperfusion. Treatment with repertaxin by continuous infusion is demonstrated to be the optimal route of administration of the compound especially in view of its clinical threrapeutic use. Because repertaxin has proven to be safe and well tolerated in different animal studies and in phase I studies in human volunteers, it is in fact a candidate novel therapeutic agent for the prevention and treatment of hepatic post-ischemic injury.

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.

Rat liver antioxidant response to iron and copper overloads

The rat liver antioxidant response to Fe and Cu overloads (0-60mg/kg) was studied. Dose- and time-responses were determined and summarized by t1/2 and C50, the time and the liver metal content for half maximal oxidative responses. Liver GSH (reduced glutathione) and GSSG (glutathione disulfide) were determined. The GSH content and the GSH/GSSG ratio markedly decreased after Fe (58-66%) and Cu (79-81%) loads, with t1/2 of 4.0 and 2.0h. The C50 were in a similar range for all the indicators (110-124μgFe/g and 40-50μgCu/g) and suggest a unique free-radical mediated process. Hydrophilic antioxidants markedly decreased after Fe and Cu (60-75%; t1/2: 4.5 and 4.0h). Lipophilic antioxidants were also decreased (30-92%; t1/2: 7.0 and 5.5h) after Fe and Cu. Superoxide dismutase (SOD) activities (Cu,Zn-SOD and Mn-SOD) and protein expression were adaptively increased after metal overloads (Cu,Zn-SOD: t1/2: 8-8.5h and Mn-SOD: t1/2: 8.5-8.0h). Catalase activity was increased after Fe (65%; t1/2: 8.5h) and decreased after Cu (26%; t1/2: 8.0h), whereas catalase expression was increased after Fe and decreased after Cu overloads. Glutathione peroxidase activity decreased after metal loads by 22-39% with a t1/2 of 4.5h and with unchanged protein expression. GSH is the main and fastest responder antioxidant in Fe and Cu overloads. The results indicate that thiol (SH) content and antioxidant enzyme activities are central to the antioxidant defense in the oxidative stress and damage after Fe and Cu overloads.

Oxidative damage to rat brain in iron and copper overloads

Increased cytosolic levels of Fe²⁺, Cu⁺and H₂O₂are central to the hypothesis that Fe and Cu toxicities are mediated by OH˙ formation and oxidative damage due to phospholipids and proteins oxidation.

Brain antioxidant responses to acute iron and copper intoxications in rats

The response of brain antioxidant system to the oxidative stress following Fe and Cu overloads involves: antioxidant consumption and an adaptive increase in antioxidant enzyme activities and protein expression.

The acute toxicity of iron and copper: biomolecule oxidation and oxidative damage in rat liver

The transition metals iron (Fe) and copper (Cu) are needed at low levels for normal health and at higher levels they become toxic for humans and animals. The acute liver toxicity of Fe and Cu was studied in Sprague Dawley male rats (200 g) that received ip 0-60 mg/kg FeCl(2) or 0-30 mg/kg CuSO(4). Dose and time-responses were determined for spontaneous in situ liver chemiluminescence, phospholipid lipoperoxidation, protein oxidation and lipid soluble antioxidants. The doses linearly defined the tissue content of both metals. Liver chemiluminescence increased 4 times and 2 times after Fe and Cu overloads, with half maximal responses at contents (C(50%)) of 110 μgFe/g and 42 μgCu/g liver, and with half maximal time responses (t(1/2)) of 4h for both metals. Phospholipid peroxidation increased 4 and 1.8 times with C(50%) of 118 μg Fe/g and 45 μg Cu/g and with t(1/2) of 7h and 8h. Protein oxidation increased 1.6 times for Fe with C(50%) at 113 μg Fe/g and 1.2 times for Cu with 50 μg Cu/g and t(1/2) of 4h and 5h respectively. The accumulation of Fe and Cu in liver enhanced the rate of free radical reactions and produced oxidative damage. A similar free radical-mediated process, through the formation HO(•) and RO(•) by a Fenton-like homolytic scission of H(2)O(2) and ROOH, seems to operate as the chemical mechanism for the liver toxicity of both metals.

Receptor binding mode and pharmacological characterization of a potent and selective dual CXCR1/CXCR2 non-competitive allosteric inhibitor

BACKGROUND AND PURPOSE

DF 2156A is a new dual inhibitor of IL-8 receptors CXCR1 and CXCR2 with an optimal pharmacokinetic profile. We characterized its binding mode, molecular mechanism of action and selectivity, and evaluated its therapeutic potential.

EXPERIMENTAL APPROACH

The binding mode, molecular mechanism of action and selectivity were investigated using chemotaxis of L1.2 transfectants and human leucocytes, in addition to radioligand and [(35) S]-GTPγS binding approaches. The therapeutic potential of DF 2156A was evaluated in acute (liver ischaemia and reperfusion) and chronic (sponge-induced angiogenesis) experimental models of inflammation.

KEY RESULTS

A network of polar interactions stabilized by a direct ionic bond between DF 2156A and Lys(99) on CXCR1 and the non-conserved residue Asp(293) on CXCR2 are the key determinants of DF 2156A binding. DF 2156A acted as a non-competitive allosteric inhibitor blocking the signal transduction leading to chemotaxis without altering the binding affinity of natural ligands. DF 2156A effectively and selectively inhibited CXCR1/CXCR2-mediated chemotaxis of L1.2 transfectants and leucocytes. In a murine model of sponge-induced angiogenesis, DF 2156A reduced leucocyte influx, TNF-α production and neovessel formation. In vitro, DF 2156A prevented proliferation, migration and capillary-like organization of HUVECs in response to human IL-8. In a rat model of liver ischaemia and reperfusion (I/R) injury, DF 2156A decreased PMN and monocyte-macrophage infiltration and associated hepatocellular injury.

CONCLUSION AND IMPLICATIONS

DF 2156A is a non-competitive allosteric inhibitor of both IL-8 receptors CXCR1 and CXCR2. It prevented experimental angiogenesis and hepatic I/R injury in vivo and, therefore, has therapeutic potential for acute and chronic inflammatory diseases.

Protection against in vivo liver ischemia-reperfusion injury by n-3 long-chain polyunsaturated fatty acids in the rat

N-3 polyunsaturated fatty acids (n-3 PUFA) affect inflammatory processes. This study evaluated the effects of dietary supplementation with fish oil on hepatic ischemia-reperfusion (IR) injury in the rat. Parameters of liver injury (serum transaminases and histology) and oxidative stress (serum 8-isoprostanes and hepatic GSH and GSSG), were correlated with NF-kappaB DNA binding and FA composition and inflammatory cytokine release. N-3 PUFA supplementation significantly increased liver n-3 PUFA content and decreased n-6/n-3 PUFA ratios. IR significantly modified liver histology and enhanced serum transaminases, 8-isoprotanes and inflammatory cytokines, with net reduction in liver GSH levels and net increment in those of GSSG. Early increase (3 h) and late reduction (20 h) in NF-kappaB activity was induced. All IR-induced changes were normalized by n-3 PUFA supplementation. In conclusion, prevention of liver IR-injury was achieved by n-3 PUFA supplementation, with suppression of oxidative stress and recovery of pro-inflammatory cytokine homeostasis and NF-kappaB functionality lost during IR.

Triptolide alleviates hepatic ischemia/reperfusion injury by attenuating oxidative stress and inhibiting NF-κB activity in mice

BACKGROUND

Hepatic I/R injury is unavoidable in liver transplantation and surgery. This remains a significant problem in surgical procedures. The purpose of this study was to investigate the effects of triptolide on liver ischemia/reperfusion (I/R) injury and related mechanisms in mice.

MATERIALS AND METHODS

Male C57BL/6 mice were randomized into four groups: (1) sham group; (2) sham-triptolide group; (3) I/R group; and (4) I-R/triptolide group. Ninety minutes of warm ischemia was induced and flow by 24 h reperfusion. Serum alanine aminotransferase and aspartate aminotransferase were assayed, pathologic alterations and (NF)-κB p65 immunohistochemistry were observed. Liver malondialdehyde (MDA) level, activity of endogenous antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, and activity of neutrophil accumulation marker myeloperoxidase (MPO) were measured. TNF-α, IL-6, and IL-1β mRNA were detected by RT-PCR, whereas nuclear factor (NF)-κB p65 and IκBα were assessed with Western blotting.

RESULTS

Plasma aminotransferase activity was higher in the I/R group than in the I/R-triptolide group. MDA level and neutrophil infiltration were also markedly reduced, while SOD, CAT, and GSH-Px levels increased in I/R-triptolide group compared with I/R group. In group 4, histopathologic changes were significantly attenuated in triptolide-treated livers. In comparison with group 3, triptolide reduced NF-κB p65 nuclear and IκBα expression, and effectively suppressed pro-inflammatory cytokine level during the I/R.

CONCLUSIONS

These results suggest that triptolide has protective effects against hepatic I/R injury. Its mechanisms might be related to reduction of oxidative stress and neutrophil infiltration and inhibition NF-κB p65 activity.

In situ and real time muscle chemiluminescence determines singlet oxygen involvement in oxidative damage during endotoxemia

Many studies have reported the occurrence of oxidative stress in different models of sepsis, but no measurements in real time and in non-invasive manner in an acute model of endotoxemia were done, being its mechanism still under debate. In the present work, we have used in situ surface chemiluminescence to evaluate the reactive oxygen species steady-state concentrations and to identify the main chemical species involved in this phenomenon. Experimental endotoxemia provoked a twofold increase in skeletal muscle chemiluminescence (control value: 31+/-4cps/cm(2)). The use of cutoff filters and D(2)O and biacetyl as specific enhancers, indicates that singlet oxygen is the main emitting species in this model. This result closely correlates with elevated TBARS levels, an index of oxidative damage to lipids. Increased NO production and NADPH oxidase activity may support the formation of ONOO(-), which in turn may originate HO, an initiator of the lipid oxidation chain. In summary, our data show for the first time that (1)O(2) is the main chemical and emitting species involved in the mechanism of oxidative stress present in an acute model of endotoxemia. This work provides new insights necessary to understand free radical mechanisms behind endotoxemic syndrome.

Thyroid hormone preconditioning: protection against ischemia-reperfusion liver injury in the rat

Recently, we reported that oxidative stress due to 3,3',5-triiodothyronine (T(3))-induced calorigenesis up-regulates the hepatic expression of mediators promoting cell protection. In this study, T(3) administration in rats (single dose of 0.1 mg/kg intraperitoneally) induced significant depletion of reduced liver glutathione (GSH), with higher protein oxidation, O(2) consumption, and Kupffer cell function (carbon phagocytosis and carbon-induced O(2) uptake). These changes occurred within a period of 36 hours of T(3) treatment in animals showing normal liver histology and lack of alteration in serum AST and ALT levels. Partial hepatic ischemia-reperfusion (IR) (1 h of ischemia via vascular clamping and 20 h reperfusion) led to 11-fold and 42-fold increases in serum AST and ALT levels, respectively, and significant changes in liver histology, with a 36% decrease in liver GSH content and a 133% increase in that of protein carbonyls. T(3) administration in a time window of 48 hours was substantially protective against hepatic IR injury, with a net 60% and 90% reduction in liver GSH depletion and protein oxidation induced by IR, respectively. Liver IR led to decreased DNA binding of nuclear factor-kappaB (NF-kappaB) (54%) and signal transducer and activator of transcription 3 (STAT3) (53%) (electromobility shift assay), with 50% diminution in the protein expression of haptoglobin (Western blot), changes that were normalized by T(3) preconditioning.

CONCLUSION

T(3) administration involving transient oxidative stress in the liver exerts significant protection against IR injury, a novel preconditioning maneuver that is associated with NF-kappaB and STAT3 activation and acute-phase response.

Interleukin-10 Gene Transfer: Prevention of Multiple Organ Injury in a Murine Cecal Ligation and Puncture Model of Sepsis

INTRODUCTION

The aim of this study was to determine the effect of immunoregulatory cytokine interleukin-10 (IL-10) gene therapy on multiple organ injury (MOI) induced by a cecal ligation and puncture (CLP) model of sepsis in mice.

METHODS

Male Balb/c mice subjected to CLP were treated with either an hIL-10-carrying vector or an empty control vector. We assessed the degree of lung, liver, and kidney tissue destruction biochemically by measuring myeloperoxidase (MPO) and malondialdehyde (MDA) activity. Histologic assessments were based on neutrophil infiltration in lung and liver tissue. IL-10 protein expression was examined immunohistochemically, and ultrastructural changes in the liver were studied by transmission electron microscopy. We analyzed the expression of tumor necrosis factor-alpha (TNFalpha) mRNA by reverse transcription polymerase chain reaction 3, 8, and 24 hours after CLP in all organs.

RESULTS

Organ damage was significantly reduced by hIL-10 gene transfer, which was associated at the tissue level with reduced MPO activity in the liver, lung, and kidney and decreased leukocyte sequestration and MDA formation in the lung. The liver MDA was not significantly higher in the hIL-10 gene therapy group than in the controls and seemed not to be affected by hIL-10 gene transfer. The reduced portal tract neutrophilic infiltration and preserved ultrastructure of the hepatocytes also showed that tissue function was not impaired. The lung and kidney TNFalpha mRNA expression was suppressed markedly in the hIL-10 gene therapy group, but liver TNFalpha mRNA expression varied over time.

CONCLUSIONS

These findings showed that IL-10 gene therapy significantly attenuated sepsis-induced MOI.

Effect of Ligustrazine on liver injury after burn trauma

This study was designed to investigate the effect of Ligustrazine on burn-induced liver injury as well as the activation of nuclear factor kappaB (NF-kappaB) in severely burned rats. Sprague-Dawley rats were divided into three groups: (1) sham group, rats who underwent sham burn; (2) control group, rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; (3) Ligustrazine group, rats given burn and lactated Ringer's solution with Ligustrazine inside for resuscitation. Liver injury was assessed at 24 h post-burn by serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as liver wet/dry weight ratio. Liver myeloperoxidase (MPO) activity was also analyzed. Hepatic NF-kappaB activity was examined by electrophoretic mobility shift assay (EMSA). Burn results in hepatic dysfunction and increased hepatic NF-kappaB activity, elevated liver wet/dry ratio and hepatic MPO activity. Ligustrazine inhibited these changes and alleviated burn-mediated hepatic dysfunction. The data indicated that Ligustrazine has a protective effect on burn-induced liver injury and possible mechanism may be attributed to its inhibitory action on the activation of NF-kappaB following burn trauma.

The Protective Effect of α-Tocopherol and GdCl3 Against Hepatic Ischemia/Reperfusion Injury

PURPOSE

To evaluate the combined effect of alpha-tocopherol and gadolinium chloride (GdCl3) in reducing lipid peroxidation after severe hepatic ischemia/reperfusion (IR) injury.

METHODS

Sixty male Wistar rats, 200-250 g, were randomly divided into six equal groups. There were two sham operation (SHAM) groups, two untreated IR groups, and two IR groups treated with GdCl3 and alpha-tocopherol (IRGT). After 60 min of total hepatic ischemia and 120 min reperfusion, one of each group was killed, liver samples were taken for malondialdehyde (MDA) and myeloperoxidase (MPO) analysis and light microscopy examination, and blood samples were analyzed for aspartate (AST) and alanine (ALT) transaminase, lactate dehydrogenase (LDH), and alpha-tocopherol content. The remaining groups were monitored for survival rate determination.

RESULTS

The mean MDA and MPO values in the SHAM, IR, and IRGT groups, respectively, were 1.117, 1.476, and 0.978 nmol/g wet tissue and 1.49, 6.26, and 1.78 (U/g). The mean alpha-tocopherol values in the SHAM, IR, and IRGT groups, respectively, were 10.4, 1.9, and 12 micromol/l. The mean serum AST, ALT, and LDH values were significantly higher in the IR group than in the SHAM group (P < 0.001), and significantly lower in the IRGT group than in the IR group (P < 0.001). Light microscopy examination revealed more severe congestion and vacuolization in the IR group than in the SHAM group, and minimal congestion and vacuolization in the IRGT group. Survival was significantly higher in the IRGT group than in the IR group.

CONCLUSION

The administration of GdCl3 and alpha-tocopherol is likely to protect the liver against lipid peroxidation by suppressing Kupffer cell and polymorphonuclear leukocyte activation and enhancing endogenous antioxidant activity.

Ligustrazine attenuates acute lung injury after burn trauma

Acute lung injury is a common complication in patients with extensive burns in which the burned area exceeds 30% of the total body surface area (TBSA). This study was undertaken to evaluate the effect of Ligustrazine on burn-induced lung injury as well as the release of interleukin-8 (IL-8) in rats to characterize the role of Ligustrazine and IL-8 in lung injury after burn trauma. Sprague-dawley rats were divided into three groups: (1) sham group, rats who underwent sham burn; (2) control group, rats given third-degree burns over 30% TBSA and lactated Ringer solution for resuscitation; and (3) Ligustrazine group, rats given burn injury and lactated Ringer's solution with Ligustrazine inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis, and lung myeloperoxidase (MPO) activity as well as lung wet/dry weight ratio. The IL-8 levels were measured in serum by enzyme-linked immunosorbent assay. These studies showed that burn trauma results in increased pulmonary leakage permeability and lung wet/dry ratio, elevated serum IL-8 levels and MPO activity, and worsened histologic condition. Ligustrazine inhibited these changes, prevented burn-mediated lung injury, and the production of IL-8. This will likely provide further evidence for ligustrazine as a therapeutic strategy in burn-induced lung injury.

Regional and transient ischemia/reperfusion injury in the liver improves therapeutic efficacy of allogeneic intraportal hepatocyte transplantation in low-density lipoprotein receptor deficient Watanabe rabbits

BACKGROUND/AIMS

Hepatocyte transplantation has the potential to become an alternative to organ transplantation for the treatment of hereditary liver disease. Currently used hepatocyte transplantation techniques are often not sufficient for phenotypic correction. In a pre-clinical model we investigated the effect of regional transient ischemia reperfusion injury and repeated infusions of allogeneic hepatocytes on LDL cholesterol levels in LDL receptor deficient hyperlipidemic Watanabe rabbits.

METHODS

A catheter was surgically inserted into the inferior mesenteric vein. Blood supply to the right liver lobe was transiently interrupted. Nine infusions of 2.5x10(7) adult allogeneic hepatocytes from white New Zealand rabbits were applied over a period of 2 months.

RESULTS

Compared to pretreatment levels LDL cholesterol decreased significantly in Watanabe rabbits with transient ischemia reperfusion injury and repeated hepatocyte transplantation (-42+/-3%). Repeated hepatocyte transplantation without transient ischemia reperfusion injury decreased LDL cholesterol levels only moderately (-11+/-4%). LDL receptor messenger RNA and proteins were detected in hepatocyte transplanted liver but not in the liver of sham treated animals.

CONCLUSIONS

Our data indicate that transient ischemia reperfusion injury of the recipient liver is safe and significantly improves the therapeutic efficacy of allogeneic hepatocyte transplantation in hyperlipidemic rabbits with congenital LDL receptor deficiency.

Noncompetitive allosteric inhibitors of the inflammatory chemokine receptors CXCR1 and CXCR2: prevention of reperfusion injury

The chemokine CXC ligand 8 (CXCL8)/IL-8 and related agonists recruit and activate polymorphonuclear cells by binding the CXC chemokine receptor 1 (CXCR1) and CXCR2. Here we characterize the unique mode of action of a small-molecule inhibitor (Repertaxin) of CXCR1 and CXCR2. Structural and biochemical data are consistent with a noncompetitive allosteric mode of interaction between CXCR1 and Repertaxin, which, by locking CXCR1 in an inactive conformation, prevents signaling. Repertaxin is an effective inhibitor of polymorphonuclear cell recruitment in vivo and protects organs against reperfusion injury. Targeting the Repertaxin interaction site of CXCR1 represents a general strategy to modulate the activity of chemoattractant receptors.

The hydroxyl radical scavenger MCI-186 protects the liver from experimental cold ischaemia-reperfusion injury

BACKGROUND

Oxidative stress contributes to hepatic ischaemia-reperfusion (IR) injury in a biphasic pattern. In addition to direct cytotoxic effects, oxidative stress also initiates the signal transduction processes that promote second-phase liver injury. The present study investigated the effects of the hydroxyl radical scavenger MCI-186 on the biphasic process of hepatic cold IR injury.

METHODS

After cold preservation for 16 h, rat livers were reperfused on an isolated liver perfusion system for 120 min with oxygenated Krebs-Henseleit bicarbonate buffer. Perfusate samples were obtained serially, and portal flow rates were also recorded. To determine whether MCI-186 affected cytokine levels that control the second-phase injury, levels of interleukin (IL) 10 and tumour necrosis factor (TNF) alpha were measured in the perfusate.

RESULTS

Addition of MCI-186 1 mg/l into the perfusate significantly improved portal flow (P<0.050), hepatic enzyme release into the perfusate (P=0.038), total bile production (P=0.029) and malondialdehyde concentration (P=0.038). Furthermore, treatment with MCI-186 led to a substantial increase in IL-10 release (P=0.032). TNF-alpha levels were not affected.

CONCLUSIONS

MCI-186, an agent ready for clinical use, appears to have direct and indirect protective effects against hepatic cold IR injury.

Spermatic cord torsion, reactive oxygen and nitrogen species and ischemia–reperfusion injury

Mammalian testes are highly sensitive to oxidative free radical damage. Acute scrotum is a clinical syndrome mainly caused by torsion of the spermatic cord that constitutes a surgical emergence affecting newborns, children and adolescents. This syndrome often leads to infertility of the ipsilateral (torted) and contralateral (not torted) testis, an outcome that makes surgical intervention mandatory. There is a controversy involving the effects of ischemia and reperfusion on ipsilateral and contralateral testes after unilateral torsion and detorsion of the spermatic cord. Conflicting reports have led to two distinct and opposite recommendations regarding surgical intervention: detortion and preservation of the ipsilateral testis, or ipsilateral orchiectomy to preserve contralateral fertility. Early detortion surgery in humans preserves fertility, but after prolonged torsion periods followed by preservation of the ipsilateral fertility of both testis is jeopardized. Lowered contralateral blood flow after unilateral testicular torsion is associated with reactive oxygen species (ROS) overgeneration and therefore with the corresponding tissue damage. Reperfusion time appears to be determinant of contralateral testes damage due to the consequent oxidative insult that accompanies the rise in ROS following ischemia-reperfusion. Nevertheless, more investigations on the molecular mechanisms and the antioxidant status in testis are necessary to ascertain the contribution of ROS to the tissue damage produced by spermatic cord torsion in experimental animals and humans.

High dose intravenous immunoglobulin g pretreatment: effect on lipid peroxidation and reperfusion injury to the liver

The aim of this study was to examine the effect of intravenous immunoglobulin G (IVIG) compared with that of gadolinium chloride (GdCl3) in the inhibition of Kupffer cell activation on lipid peroxidation after severe total hepatic ischemia/reperfusion (I/R). Male Wistar rats ( n = 40) were randomly divided into four equal groups: a sham-operation group, a control I/R group, and two I/R groups pretreated with either IVIG or GdCl3 intravenously. Following 60 minutes of total hepatic ischemia and 120 minutes of reperfusion, the rats were sacrificed and liver and blood samples collected. Additional animals ( n = 80) were followed up for survival rate determination. Results showed that I/R decreased the survival rate to 10%, increased the levels of aspartate (AST) and alanine (ALT) transaminase and lactate dehydrogenase (LDH) in serum to 2487, 2189, and 4236 IU/L, respectively, and increased malondialdehyde (MDA) levels in liver to 1.552 nmol/g compared with 1.114 nmol/g in the sham operation group. Pretreatment with GdCl3 increased the survival rate to 50% and decreased the levels of AST, ALT, and LDH in serum to 1496, 1298, and 3245 IU/l, respectively. Pretreatment with IVIG increased the survival rate to 60% and decreased the levels of AST, ALT, and LDH in serum to 449, 367, and 1456 IU/l, respectively, and the levels of MDA in liver to 1.153 and 1.148 nmol/g for GdCl3 and IVIG respectively. Histologic examination showed protection of liver parenchyma in the animals treated with GdCl3 or IVIG.

Hepatic ischemia-reperfusion syndrome after partial liver resection (LR): hepatic venous oxygen saturation, enzyme pattern, reduced and oxidized glutathione, procalcitonin and interleukin-6

The hepatic ischemia-reperfusion syndrome was investigated in 28 patients undergoing elective partial liver resection with intraoperative occlusion of hepatic inflow (Pringle maneuver) using the technique of liver vein catheterization. Hepatic venous oxygen saturation (ShvO2) was monitored continuously up to 24 hours after surgery. Aspartate aminotransferase, glutamate dehydrogenase, gamma-glutamyl transpeptidase, pseudocholinesterase, alpha-glutathione S-transferase, reduced and oxidized glutathione, procalcitonine, and interleukin-6 were serially measured both before and after Pringle maneuver during the resection and postoperatively in arterial and/or hepatic venous blood. ShvO2 measurement demonstrated that peri- and postoperative management was suitable to maintain an optimal hepatic oxygen supply. As expected, we were able to demonstrate a typical enzyme pattern of postischemic liver injury. There was a distinct decrease of reduced glutathione levels both in arterial and hepatic venous plasma after LR accompanied by a strong increase in oxidized glutathione concentration during the phase of reperfusion. We observed increases in procalcitonin and interleukin-6 levels both in arterial and hepatic venous blood after declamping. Our data support the view that liver resection in man under conditions of inflow occlusion resulted in ischemic lesion of the liver (loss of glutathione synthesizing capacity with disturbance of protection against oxidative stress) and an additional impairment during reperfusion (liberation of reactive oxygen species, local and systemic inflammation reaction with cytokine production). Additionally, we found some evidence for the assumption that the liver has an export function for reduced glutathione into plasma in man.

Singlet oxygen: the relevance of extracellular production mechanisms to oxidative stress in vivo

Since the physiological relevance of 1O2 independent of photosensitization has been controversial, we review proposed reaction mechanisms for its extracellular production in vivo and discuss the relevance of this production to oxidative stress. We conclude that extracellular 1O2 production by the spontaneous dismutation of O2*- does have physiological relevance. Also, extracellular 1O2 production by the eosinophil peroxidase-H2O2-bromide system could have physiological relevance. As regards the other reactions discussed in this review, the evidence is not sufficient to warrant any conclusions as to the physiological relevance of these to extracellular 1O2 production. What is evident is that the microenvironment will have a significant influence on the success or failure of extracellular 1O2 production. To date, most demonstrations of 1O2 production by physiologically relevant mechanisms have used conditions that minimize competitive reactions. More research demonstrating how physiologically relevant competitive reactions influence extracellular 1O2 production is needed.

Beneficial effect of MCI-186 on hepatic warm ischemia-reperfusion in the rat

Despite growing evidence that reactive oxygen species are responsible for deleterious effects of ischemia-reperfusion (I/R) injury of the liver, there exists, until now, no reliable antioxidant therapeutics applicable in the clinical setting. We investigated the effects of free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), using an isolated liver perfusion model to elucidate its possible therapeutic effects on hepatic warm I/R injury. Isolated livers from Wistar rats were reperfused for 120 min with an oxygenated Krebs-Henseleit bicarbonate buffer after 1 hr of warm ischemia. Addition of MCI-186 (1 mg/L) into the perfusate significantly improved portal flow, hepatic enzyme release into the perfusate, total bile production, histologic alteration, and malondialdehyde concentration but not sinusoidal endothelial cell function as assessed by the clearance of hyaluronic acid. MCI-186 seems to have protective effects against hepatic warm I/R injury by attenuating the damage of the hepatocyte, which is the major target of oxidative damage in this model.

The role of mitochondrial nitric oxide synthase in inflammation and septic shock

Nitric oxide and cytokines constitute the molecular markers and the intercellular messengers of inflammation and septic shock. Septic shock occurs with an exacerbated inflammatory response that damages tissue mitochondria. Skeletal muscle appears as one of the main target organs in septic shock, showing an increased nitric oxide (NO) production, an early oxidative stress, and contractile failure. Mitochondria isolated from rat and human skeletal muscle in septic shock show a markedly increased NO generation and a decreased state 3 respiration, more marked with nicotinamide adenine dinucleotide (NAD)-linked substrates than with succinate, without uncoupling or impairment of phosphorylation. One of the current hypothesis for the molecular mechanisms of septic shock is that the enhanced NO production by mitochondrial nitric oxide synthase (mtNOS) leads to excessive peroxynitrite (ONOO(-)) production and protein nitration in the mitochondrial matrix, to mitochondrial dysfunction and to contractile failure. Surface chemiluminescence is a useful assay to assess inflammation and oxidative stress in in situ liver and skeletal muscle. Liver chemiluminescence in inflammatory processes and phagocyte chemiluminescence have been found spectrally different from spontaneous liver chemiluminescence with increased 440-600 nm emission, likely due to NO and ONOO(-) participation in the reactions leading to the formation of excited species.

Microvascular dysfunction induced by reperfusion injury and protective effect of ischemic preconditioning

Hepatic ischemia/reperfusion injury has immediate and deleterious effects on the outcome of patients after liver surgery. The precise mechanisms leading to the damage have not been completely elucidated. However, there is substantial evidence that the generation of oxygen free radicals and disturbances of the hepatic microcirculation are involved in this clinical syndrome. Microcirculatory dysfunction of the liver seems to be mediated by sinusoidal endothelial cell damage and by the imbalance of vasoconstrictor and vasodilator molecules, such as endothelin (ET), reactive oxygen species (ROS), and nitric oxide (NO). This may lead to no-reflow phenomenon with release of proinflammatory cytokines, sinusoidal plugging of neutrophils, oxidative stress, and as an ultimate consequence, hypoxic cell injury and parenchymal failure. An inducible potent endogenous mechanism against ischemia/reperfusion injury has been termed ischemic preconditioning. It has been suggested that preconditioning could inhibit the effects of different mediators involved in the microcirculatory dysfunction, including endothelin, tumor necrosis factor-alpha, and oxygen free radicals. In this review, we address the mechanisms of liver microcirculatory dysfunction and how ischemic preconditioning could help to provide new surgical and/or pharmacological strategies to protect the liver against reperfusion damage.

Ischemic preconditioning attenuates the oxidant-dependent mechanisms of reperfusion cell damage and death in rat liver

In an in vivo rat model of liver ischemia followed by reperfusion a consistent appearance of necrosis and activation of biochemical pathways of apoptosis was reproduced and monitored after 30 minutes reperfusion. Preconditioning by application of a short cycle of ischemia-reperfusion (10 minutes + 10 minutes) positively conditioned recovery of the organ at reperfusion, attenuating both necrotic and apoptotic events. Preconditioning at least halved cell oxidative damage occurring early at reperfusion, and as a major consequence, the increase of cytolysis and apoptosis occurring at reperfusion was about 50% less. The attenuation of both pathways of cell death by preconditioning appeared at least partly related to its modulate action on H(2)O(2) and 4-hydroxy-2,3-trans-nonenal production. The overall data point to a marked diminished oxidant generation and oxidative reactions as one major possible mechanism through which ischemic preconditioning exerts protection against necrotic and apoptotic insult to the postischemic liver.

Transferrin receptor gene expression and transferrin-bound iron uptake are increased during postischemic rat liver reperfusion

Iron-catalyzed production of reactive oxygen species is a cause of liver injury after ischemia/reperfusion (I/R). The aim of the present study was to address the regulation of transferrin receptor (TfR), which mediates cellular iron uptake, during I/R. The molecular mechanisms controlling TfR gene expression in vivo during I/R of rat liver were investigated by molecular biology procedures. We also analyzed transferrin-bound iron uptake into surviving liver slices. Increased amounts of TfR protein and messenger RNA (mRNA) were found 2 to 6 hours after reestablishment of blood supply. RNA bandshift analysis showed that iron regulatory protein (IRP) activity was decreased in the first hours of reperfusion, thus indicating that IRP-mediated mRNA stabilization was not involved in early TfR upregulation. On the contrary, increased transcription of the TfR gene in isolated nuclei was observed during reperfusion; during the ischemic phase this was preceded by enhanced binding of hypoxia inducible factor (HIF-1) to a DNA sequence derived from the TfR promoter. TfR2 mRNA levels were also enhanced after reperfusion. The increased expression of TfR at the cell surface resulted in increased uptake of transferrin-bound-iron into surviving liver slices; however, iron was not incorporated into ferritin. In conclusion, HIF-1 mediated activation of TfR gene transcription and IRP-mediated increase of TfR mRNA stability ensure a steady induction of TfR, and hence higher iron uptake in reperfused rat liver. TfR-mediated entry of the metal into liver cells may represent a source of catalytically active iron, which may play a role in reperfusion damage.

Ischemic preconditioning: a defense mechanism against the reactive oxygen species generated after hepatic ischemia reperfusion

BACKGROUND

Preconditioning protects against both liver and lung damage after hepatic ischemia-reperfusion (I/R). Xanthine and xanthine oxidase (XOD) may contribute to the development of hepatic I/R.

OBJECTIVE

To evaluate whether preconditioning could modulate the injurious effects of xanthine/XOD on the liver and lung after hepatic I/R.

METHODS

Hepatic I/R or preconditioning previous to I/R was induced in rats. Xanthine and xanthine dehydrogenase/xanthine oxidase (XDH/XOD) in liver and plasma were measured. Hepatic injury and inflammatory response in the lung was evaluated.

RESULTS

Preconditioning reduced xanthine accumulation and conversion of XDH to XOD in liver during sustained ischemia. This could reduce the generation of reactive oxygen species (ROS) from XOD, and therefore, attenuate hepatic I/R injury. Inhibition of XOD prevented postischemic ROS generation and hepatic injury. Administration of xanthine and XOD to preconditioned rats led to hepatic MDA and transaminase levels similar to those found after hepatic I/R. Preconditioning, resulting in low circulating levels of xanthine and XOD activity, reduced neutrophil accumulation, oxidative stress, and microvascular disorders seen in lung after hepatic I/R. Inhibition of XOD attenuated the inflammatory damage in lung after hepatic I/R. Administration of xanthine and XOD abolished the benefits of preconditioning on lung damage.

CONCLUSIONS

Preconditioning, by blocking the xanthine/XOD pathway for ROS generation, would confer protection against the liver and lung injuries induced by hepatic I/R.

Comparison of ischemic preconditioning and intermittent and continuous inflow occlusion in the murine liver

OBJECTIVE

To compare protection of the liver by ischemic preconditioning and intermittent inflow occlusion in a mouse model of prolonged periods of ischemia.

SUMMARY BACKGROUND DATA

Preconditioning (short ischemic stress prior to a prolonged period of ischemia) and intermittent inflow occlusion protect the liver against reperfusion injury. This is the first study comparing these two modalities with continuous inflow occlusion (control).

METHODS

Mice were subjected to 75 or 120 minutes of 70% hepatic ischemia and 3 hours of reperfusion. Each ischemic period was evaluated using three different protocols: continuous ischemia (control), preconditioning (10 minutes ischemia and 15 minutes reperfusion) prior to the prolonged ischemic insult, and intermittent clamping (cycles of 15 minutes ischemia and 5 minutes reperfusion). Organ injury was evaluated using serum levels of aspartate aminotransferase (AST), hematoxylin and eosin staining, and specific markers of apoptosis (cytochrome C release, caspase 3 activity, and TUNEL staining). Animal survival was determined using a model of total hepatic ischemia.

RESULTS

Intermittent inflow occlusion and ischemic preconditioning were both protective against ischemic insults of 75 and 120 minutes compared with controls (continuous ischemia only). Protection against 75 minutes of ischemia was comparable in the intermittent clamping and the ischemic preconditioning group, whereas intermittent clamping was superior at 120 minutes of ischemia. One hundred percent animal survival was observed after 75 minutes of total hepatic ischemia using both protective protocols, whereas all animals subjected to continuous ischemia died after surgery. After 120 minutes of ischemia, intermittent inflow occlusion was associated with better animal survival (71%) compared with preconditioning (14%).

CONCLUSIONS

Preconditioning and intermittent clamping are both protective against prolonged periods of ischemia. In the clinical setting, preconditioning is superior for ischemic periods of up to 75 minutes because it is not associated with blood loss during transection of the liver. However, for prolonged ischemic insults exceeding 75 minutes, intermittent clamping is superior to preconditioning.

Tumor necrosis factor alpha, but not Fas, mediates hepatocellular apoptosis in the murine ischemic liver

BACKGROUND & AIMS

Apoptosis of hepatocytes is a central feature of ischemic injury in the liver. The aim of this study was to identify extracellular inducers of apoptosis in the murine ischemic liver.

METHODS

Involvement of tumor necrosis factor (TNF)-alpha and Fas signaling was evaluated using various knockout mice (TNF-receptor 1 [TNF-R1]-/-, Fas[lpr]-/-, and Fas ligand[gld]-/-) and wild-type mice pretreated with pentoxifylline, an inhibitor of TNF-alpha synthesis.

RESULTS

Expression of TNF-alpha was increased after ischemia and reperfusion in wild-type mice and TNF-R1-deficient mice when compared with sham-operated animals. Pentoxifylline prevented up-regulation of TNF-alpha expression. Inhibition of TNF-alpha resulted in significant decrease of serum aspartate aminotransferase levels and prolonged animal survival. Markers of apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining, cytochrome C release, and caspase 3 activity) were consistently decreased, and animal survival was prolonged after blocking TNF-alpha. In contrast, inhibition of Fas signaling did not alter parameters of tissue injury or apoptosis, and animal survival remained unchanged.

CONCLUSIONS

We identify TNF-alpha as a crucial inducer of apoptotic cell death in the ischemic liver. A role for Fas could not be identified. These findings may lead to novel strategies to prevent ischemic injury of the liver.

Procalcitonin following elective partial liver resection--origin from the liver?

BACKGROUND

The origin of the inflammatory peptide procalcitonin (PCT) is still unknown. In the present study PCT concentrations in arterial and hepatic-venous blood were examined in patients undergoing elective partial liver resection (LR) using a fiberoptic pulmonary arterial catheter placed in a liver vein to obtain further information on the origin of PCT.

METHODS

In 28 patients (21 male/7 female; average age of 58.8+/-8.8 years) undergoing LR, arterial and hepatic venous PCT concentrations were measured during 24 h perioperatively. The parallel blood withdrawals occurred immediately before the Pringle maneuver (Hx), 2 min, 1, 2, 6, 12, and 24 h after Hx. Over the whole period, the oxygen saturation in hepatic venous blood (ShvO2) was monitored. PCT concentrations were assayed by immunoluminometry.

RESULTS

We observed a significant increase in PCT concentration already 6 h after Hx compared to the values before Hx. Twenty-four hours after Hx we found the highest plasma concentrations. It was conspicuous that hepatic venous PCT concentrations were always higher than the arterial ones (significantly from the 6th hour after Hx). There was no correlation between the courses of ShvO2 and PCT rise. A significant correlation was verified between Hx duration and PCT concentration measured 24 h after Hx both in the hepatic venous and arterial blood.

CONCLUSIONS

The results of our investigation can be interpreted as evidence that liver (or the hepatosplanchnicus?) is a source of PCT. The mechanism of PCT induction cannot be clarified by our study: whether the induction of PCT was caused by an endotoxin translocation during the impeded splanchnic outflow or by the direct surgery-induced lesion (hypoxia) of the liver remains unclear. However, the latter appears more probable because of the observed correlation between Hx duration and PCT concentration rise.

Cardiac toxicity of singlet oxygen: implication in reperfusion injury

Oxygen-derived free radicals (O2.-, H2O2, and .OH) that are produced during postischemic reperfusion are currently suspected to be involved in the pathogenesis of tissue injury. Another reactive oxygen species, the electronically excited molecular oxygen (1O2), is of increasing interest in the area of experimental research in cardiology. In this review are discussed the main potential sources of singlet oxygen in the organism, particularly in the myocardium, the various cardiovascular cytotoxic effects induced by this reactive oxygen intermediate, and the growing evidence of its involvement in ischemia/reperfusion injury.