Effect of ischemia and reperfusion on hepatic regeneration following partial hepatectomy in cirrhotic rat liver

BACKGROUND: Several cutaneous tumors are characteristically associated with considerable and sometimes incapacitating pain. OBJECTIVE: A review of the histologic features of these tumors, subjective characteristics of the pain, hypotheses proposed to explain the mechanism of pain production by the tumor, and treatments that have been effective in abolishing or relieving the patient's perception of the stimulus. METHODS: Review of case reports as well as studies that have proposed mechanisms of pain production based on histologic, electron microscopic, and pharmacologic studies. RESULTS: Several hypotheses may be equally valid in explaining the cause of pain of a single tumor type, while no apparent cause is found in other types of tumors. There is variability in the success of a treatment between patients. CONCLUSION: Our understanding of the mechanism of pain production by cutaneous tumors is limited by the small number of studies (and sample size) addressing the issue as well as by our incomplete general understanding of pain production.     

Tumor necrosis factor-alpha in ischemia and reperfusion injury in rat lungs

The effects of both recombinant rat tumor necrosis factor-alpha (TNF-alpha) and an anti-TNF-alpha antibody were studied in isolated buffer-perfused rat lungs subjected to either 45 min of nonventilated [ischemia-reperfusion (I/R)] or air-ventilated (V/R) ischemia followed by 90 min of reperfusion and ventilation. In the I/R group, the vascular permeability, as measured by the filtration coefficient (Kfc), increased three- and fivefold above baseline after 30 and 90 min of reperfusion, respectively (P < 0.001). Over the same time intervals, the Kfc for the V/R group increased five- and tenfold above baseline values, respectively (P < 0.001). TNF-alpha measured in the perfusates of both ischemic models significantly increased after 30 min of reperfusion. Recombinant rat TNF-alpha (50,000 U), placed into perfusate after baseline measurements, produced no measurable change in microvascular permeability in control lungs perfused over the same time period (135 min), but I/R injury was significantly enhanced in the presence of TNF-alpha. An anti-TNF-alpha antibody (10 mg/rat) injected intraperitoneally into rats 2 h before the lung was isolated prevented the microvascular damage in lungs exposed to both I/R and V/R (P < 0.001). These results indicate that TNF-alpha is an essential component at the cascade of events that cause lung endothelial injury in short-term I/R and V/R models of lung ischemia.     

In vivo evaluation of leukocyte dynamics in retinal ischemia reperfusion injury

PURPOSE: To evaluate quantitatively leukocyte dynamics in vivo in the rat retinal microcirculation during ischemia reperfusion injury with the use of acridine orange digital fluorography. METHODS: Retinal ischemia was induced in anesthetized pigmented rats by a temporary ligation of the optic nerve. After 60 minutes of ischemia, leukocyte behavior in the retinal microcirculation was evaluated, with acridine orange digital fluorography--consisting of a scanning laser ophthalmoscope and the fluorescent nuclear dye, acridine orange--during reperfusion at 1, 2, 4, 6, 12, 24, 48, 96, and 168 hours. The obtained images were recorded on videotape and analyzed with a computer-assisted image analysis system. RESULTS: Rolling leukocytes along the major retinal veins were observed in treated rats during the reperfusion period; no rolling leukocytes were observed in the control rats. The number of rolling leukocytes gradually increased and peaked at 102 +/- 40 cells/minute 12 hours after reperfusion; few rolling leukocytes were observed at 96 hours. The velocity of rolling leukocytes at 12 hours (19.1 +/- 3.5 microns/second; P < 0.05) was significantly lower than that at the other three times. No rolling leukocytes were observed along the arterial walls throughout the experiments. The number of accumulated leukocytes increased as time elapsed, peaked at 931 +/- 187 cells/mm2 24 hours after reperfusion, and decreased thereafter. CONCLUSIONS: Leukocyte dynamics in the retinal microcirculation can be quantitatively evaluated during ischemia reperfusion injury.     

Antithrombin reduces ischemia/reperfusion injury of rat liver by increasing the hepatic level of prostacyclin

Reading disability (RD), or dyslexia, is a complex cognitive disorder manifested by difficulties in learning to read, in otherwise normal individuals. Individuals with RD manifest deficits in several reading and language skills. Previous research has suggested the existence of a quantitative-trait locus (QTL) for RD on the short arm of chromosome 6. In the present study, RD subjects' performance in several measures of word recognition and component skills of orthographic coding, phonological decoding, and phoneme awareness were individually subjected to QTL analysis, with a new sample of 126 sib pairs, by means of a multipoint mapping method and eight informative DNA markers on chromosome 6 (D6S461, D6S276, D6S105, D6S306, D6S258, D6S439, D6S291, and D6S1019). The results indicate significant linkage across a distance of at least 5 cM for deficits in orthographic (LOD = 3.10) and phonological (LOD = 2.42) skills, confirming previous findings.     

Inhibition of nitric oxide synthesis aggravates reperfusion injury after hepatic ischemia and endotoxemia

The potential role of nitric oxide (NO) was investigated in the pathophysiology of liver injury after priming with 20 min hepatic ischemia-reperfusion and administration of .5 mg/kg Salmonella enteritidis endotoxin. Liver injury during the early reperfusion phase of 4 h was characterized by severe vascular oxidant stress, lipid peroxidation (LPO), neutrophil infiltration, and a 33% reduction of the microvascular blood flow in the liver. Inhibition of NO synthesis with N omega-nitro-L-arginine methyl ester hydrochloride (L-NAME) aggravated liver injury by 90%, reduced LPO, and did not affect liver neutrophils but further impaired microvascular blood flow. Treatment with the NO-donor spermine-NONOate or L-arginine did not affect these parameters in postischemic animals, however, treatment did restore all values of L-NAME-treated animals back to disease control levels. These data suggest that endogenous NO formation is sufficient to limit ischemic liver injury during reperfusion but inhibition of NO synthesis will result in additional ischemic damage. NO may also be involved in scavenging of superoxide in the vasculature and in inducing LPO.     

Role of endothelins and nitric oxide in hepatic reperfusion injury in the rat

In epithelial cells, alpha-, beta-, and gamma-catenin are involved in linking the peripheral microfilament belt to the transmembrane protein E-cadherin. alpha-Catenin exhibits sequence homologies over three regions to vinculin, another adherens junction protein. While vinculin is found in cell-matrix and cell-cell contacts, alpha-catenin is restricted to the latter. To elucidate, whether vinculin is part of the cell-cell junctional complex, we investigated complex formation and intracellular targeting of vinculin and alpha-catenin. We show that alpha-catenin colocalizes at cell-cell contacts with endogenous vinculin and also with the transfected vinculin head domain forming immunoprecipitable complexes. In vitro, the vinculin NH2-terminal head binds to alpha-catenin, as seen by immunoprecipitation, dot overlay, cosedimentation, and surface plasmon resonance measurements. The Kd of the complex was determined to 2-4 x 10(-7) M. As seen by overlays and affinity mass spectrometry, the COOH-terminal region of alpha-catenin is involved in this interaction. Complex formation of vinculin and alpha-catenin was challenged in transfected cells. In PtK2 cells, intact alpha-catenin and alpha-catenin1-670, harboring the beta-catenin- binding site, were directed to cell-cell contacts. In contrast, alpha-catenin697-906 fragments were recruited to cell-cell contacts, focal adhesions, and stress fibers. Our results imply that in vivo alpha-catenin, like vinculin, is tightly regulated in its ligand binding activity.     

Modulation of adenosine effects in attenuation of ischemia and reperfusion injury in rat heart

We investigated whether xanthine oxidase-derived superoxide radical generation could be modified by interfering with adenosine transport and metabolism in reducing myocardial injury during post-ischemic reperfusion. Isolated rat hearts perfused at constant pressure were subjected to 20 min of pretreatment with test agents, followed by 40 min global ischemia and 30 min reperfusion with or without test agents. In hearts treated with adenosine deaminase inhibitor, erythro 9-(2-hydroxy-3-nonyl) adenine (EHNA), alone or together with a selective nucleoside transport blocker, p-nitrobenzylthioinosine (NBMPR), the accumulated amount of O-2. was significantly reduced [10.2+/-0.97, 11.6+/-2.4, 8.1+/-0.51, respectively, v 31.6+/-2.1 (s. e.) nmol/wet g/30 min in ischemic control, P<0.01]. A positive correlation between O-2. and inosine release was observed in the initial 5 min of reperfusion in hearts treated with either EHNA or NBMPR ( r=0.475, P<0.05). Furthermore, the accumulated amount of LDH release showed positive correlation with that of O-2. among the same groups (r=0.474, P<0.05). Both EHNA and NBMPR had the cardioprotective effect on the recovery of left ventricular end-diastolic pressure (LVEDP), ATP repletion, and build up of endogenous adenosine. This study suggests that : (1) adenosine metabolism can be manipulated towards the formation of O-2. during reperfusion, and it has an important bearing on the cardiac recovery of ischemic myocardium, (2) the generation of O-2. is related to only inosine release during initial reperfusion.     

Endopeptidase inhibitors decrease myocardial ischemia/reperfusion injury in an in vivo rabbit model

Periods of ischemia followed by reperfusion of the ischemic tissue are associated with myocardial damage and ventricular arrhythmia. Angiotensin converting enzyme inhibitors limit the occurrence of these arrhythmias. The protective effects of angiotensin converting enzyme inhibitors may be due to inhibition of bradykinin (BK) degradation, rather than inhibition of angiotensin II formation. Other enzymes which catabolize BK include the endopeptidases EP24.11 and EP24.15. The purpose of this study was to determine if inhibitors of EP24.11 and EP24.15 decrease ischemia/reperfusion injury and if this protection is mediated by BK receptors. Rabbits were anesthetized and prepared for recording of cardiovascular parameters. The chest was opened and a left ventricular artery occluded for 30 min, followed by a 2-hr reperfusion period. Infarct size was determined using triphenyl tetrazolium chloride staining immediately after reperfusion. The enzyme inhibitors, ramiprilat, N-[1-(R,S)-carboxy-3-phenylpropyl]-Phe-pAB, and N[1-(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-pAb, singly and in combinations were administered 3 min before reperfusion. Compared to saline (32.1 +/- 2.1), ramiprilat (18.3 +/- 2.8) and the EP inhibitors (14.4 +/- 1.4 for the combination) significantly decreased infarct size, with the greatest decrease occurring when all three inhibitors were combined (10.6 +/- 1.5). The protective effect of the EP inhibitors was blocked by the BK2 receptor antagonist, HOE 140 (30.1 +/- 2.6). Enzyme assays demonstrated EP24.11 and EP24.15 in the rabbit heart. We conclude that the EP inhibitors decreased ischemia/reperfusion injury by protecting BK from metabolism and that a combination of inhibitors provides superior protection to that given by a single agent.     

Alterations in glutathione peroxidase activity following reperfusion injury to rat liver

Prevention of cellular damage after warm ischemia is of major importance in liver transplantation. In this study, we determined the extent to which lipid peroxides contribute to the pathogenesis of hepatic cell damage induced by transient warm ischemia with subsequent reperfusion. In addition, the function and immunohistochemical features of glutathione peroxidase, a potent physiological lipid peroxide scavenger of the liver, was assessed. Reperfusion following 15 or 30 minutes of warm ischemia resulted in a significant elevation in serum and liver lipid peroxidase (LPO) levels. In addition, necrosis of the hepatic periportal area accompanied with remarkable rises in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were observed. In contrast, 30 min of ischemia without reperfusion caused minimal hepatocellular damage. The adverse changes after ischemia/reperfusion were minimized by pretreatment with superoxide dismutase (SOD). These results indicate that increased lipid peroxidation by production of radicals after reperfusion caused the liver cell damage. After ischemia/reperfusion, liver glutathione peroxidase (GSH-PO) activity was significantly decreased and its location altered in the damaged liver. These findings suggest that GSH-PO contributes significantly to the protection against hepatic reperfusion injuries.     

L-arginine treatment in ischemia/reperfusion injury

We tested whether treatment with exogenous L-arginine, the precursor of nitric oxide (NO), could protect the skeletal muscle from ischemia/reperfusion (I/R) injury. A rabbit hindlimb I/R model (2.5 h ischemia/2 h reperfusion) was used. Morphological changes were elucidated by morphometry. Plasma concentrations of malondialdehyde (pMDA), as well as L-arginine and L-citrulline content in the plasma and skeletal muscle were measured. I/R injury in the skeletal muscle was manifested by development of prominent interstitial edema (fraction of interfiber area was 26.23% vs 15.09% in sham operated control, p < .005) and severe microvascular constriction (capillary area was 11.41 microns2 vs 16.92 in control, p <.005). These changes were accompanied by increased pMDA levels, indicating a process of lipid peroxidation in the cell membranes. L-arginine treatment (4 mg/kg/min intravenously, for 1 h, infusion initiated 30 min before reperfusion) caused an intracellular accumulation of this amino acid in the SM. Intracellular concentrations of L-citrulline increased (201.0 mumol/dm3 after reperfusion vs 176.0 before ischemia onset, p < .005), suggesting stimulated endogenous NO synthesis. L-arginine treatment protected capillary constriction (capillary area was 17.64 microns2 vs 11.41 in the untreated animals, p < .0005) and reduced interstitial edema after reperfusion (fraction of interfiber area was 17.80% vs 26.23 in untreated animals, p < 0.005). The protective effect of L-arginine treatment on I/R injury of SM may be related to its ability to prevent microvascular constriction and reduce permeability disorders by the stimulation of endogenous NO production.     

Ischemic preconditional protection of ischemia reperfusion injury on isolated hearts of ground squirrel and rat

The protective effects of ischemic preconditioning on ischemia-reperfusion injury was investigated using isolated Langendorff perfusing hearts from ground squirrel and rat. In Preconditioning I group hearts were first perfused with Krebs-Henseleit solution for 10 min to establish a steady state, then stopped for 15 min to establish global ischemia, and finally followed by 10 min ischemia and 10 min reperfusion. In Preconditioning II group there were three cycles of 5 min ischemia + 5 min reperfusion after 10 min equilibration and then the final 10 min ischemia and 10 min reperfusion were followed. It was found that in group I during the final 10 min ischemia period there was remarkable augmentation of CK release from both animal's hearts. But in group II CK release decreased markedly during the same ischemic period. CK release during final 10 min reperfusion period also decreased significantly in group II in comparison with group I. The incidence of arrhythmias occurred in both animal's hearts was markedly reduced in group II rather than group I. In conclusion, short episode ischemic preconditioning protect subsequent ischemia-reperfusion injury on isolated hearts from ground squirrel and rat.     

A comparison of antioxidant enzyme activities in organ-cultured rhesus monkey lenses following peroxide challenge

PURPOSE: To analyze the activities of catalase, glutathione peroxidase and superoxide dismutase, three enzymes involved in the detoxification of reactive oxygen species in organ-cultured Rhesus monkey lenses. METHODS: Lenses freshly obtained from Rhesus monkeys were incubated at 37 degrees C for 2 h and assessed for lens integrity. Lenses were then oxidatively stressed by exposure to a bolus of hydrogen peroxide. The three enzyme activities were assayed 2, 4 and 24 h after exposure to the peroxide challenge. RESULTS: Freshly dissected lenses placed in organ culture exhibited a 20% decrease in catalase activity within 2 h. During the course of a 24 h incubation, catalase activity continued to decrease to a level 58% below that of freshly dissected monkey lenses. In contrast, the activity levels of both glutathione peroxidase and superoxide dismutase increased dramatically within the first 2 h of organ culture, with superoxide dismutase being most affected. Although glutathione peroxidase activity declined with incubation time, its level at the end of 24 h was still 36% greater than that of the fresh lenses. Superoxide dismutase activity remained elevated throughout the 24 h incubation period. The addition of a bolus of 0.25mM H2O2 to monkey lenses in culture had no effect on catalase activity. Two h after the peroxide insult, glutathione peroxidase activity decreased in comparison to control levels while the activity of superoxide dismutase increased by 43%. After 24 h, superoxide dismutase activity returned to values equivalent to the controls. In lenses challenged with 0.50mM H2O2, catalase and glutathione peroxidase activities decreased at 2 h, while superoxide dismutase activity increased 67% above control levels. At subsequent timepoints, catalase activity increased and reached control levels. In contrast, glutathione peroxidase activity continued to decrease with time eventually reaching fresh lens levels. Superoxide dismutase activity levels remained elevated and were equivalent to control values at 24 h. CONCLUSIONS: The data indicate that placement of monkey lenses into an organ culture system represents an environmental change sufficient to cause a response in antioxidant enzyme levels. The addition of H2O2 to this environment caused only superoxide dismutase to be stimulated above control lens levels.     

Interaction of nitric oxide and endothelin-1 in ischemia/reperfusion injury of rat heart

Although several studies have demonstrated that nitric oxide appears to be cardioprotective and endothelin-1 (ET-1) deleterious in myocardial ischemia/reperfusion injury, their interactions in the intact heart are unknown. Therefore, coronary effluent and interstitial fluid ("transudate") levels of ET-1 and cyclic GMP, an indirect measure of nitric oxide production, were determined simultaneously in normoxic and reperfused hearts and compared with myocardial and coronary function. Rat hearts were buffer-perfused at 9 ml/min/g heart wet weight for 45 min (baseline), followed either by another 45 min of perfusion (normoxia), or 15 min of total global ischemia and 30 min reperfusion. Hearts received, from 42-90 min, either vehicle, the inhibitor of nitric oxide formation NG-nitro-L-arginine (L-NNA; 200 micromol/l), the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine (SNAP; 200 micromol/l), or the ET receptor antagonist PD 142893 (200 nmol/l). Both mediators were released preferentially into the vascular lumen which resulted in similar luminal and interstitial concentrations of cyclic GMP, but three-fold higher levels of ET-1 in tissue because of the higher effluent than transudate flow rate. L-NNA increased the release of ET-1 and worsened coronary function, whereas SNAP had opposite effects. On reperfusion, considerable functional impairment was observed, although levels of cyclic GMP both in the vascular and tissue compartment were not reduced, but even increased. Reperfusion functional impairment was aggravated after inhibiting the synthesis of nitric oxide, whereas SNAP restored cardiac and coronary function close to pre-ischemic level. Deterioration of function corresponded with an increased level, and improvement with a decreased level of intersitial ET-1 at the onset of reperfusion. PD 142893 was similarly cardioprotective as SNAP both in normoxia and reperfusion. These results suggest that in reperfusion, cardiac function is depressed, despite increased rather than decreased endogenous nitric oxide production, largely due to the prevalence of the deleterious effects of ET-1 which are overcome by antagonism of ET receptors or exogenous nitric oxide supplied by SNAP.     

Changes in hepatic enzyme activities related to ethanol metabolism in mice following chronic ethanol administration

Male mice of three strains, C57BL, DBA and C3H/He, were fed on commercial food with 10% (v/v) ethanol solution as drinking liquid ad libitum for eighty days, and the changes in the activities of enzymes in the metabolic pathway of ethanol in the liver were examined. C57BL and C3H/He mice showed a preference for drinking the 10% (v/v) ethanol solution, while DBA mice did not. The ethanol intake g/g of body weight of C3H/He mice showed the highest value among all three strains and that of C57BL mice tended to show higher value than that of DBA mice. The liver weights of C57BL and C3H/He mice increased significantly following chronic ethanol administration, but that of DBA did not. The cytosolic enzyme alcohol dehydrogenase (ADH) showed no changes in any of the strains following chronic ethanol administration. The microsomal ethanol-oxidizing system (MEOS) of C57BL mice exhibited approximately 2-fold higher activity compared to that of DBA and C3H/He mice but did not increase in any strain following chronic ethanol administration. However, the microsomal aniline hydroxylase activity in the liver increased significantly in C57BL and C3H/He mice following chronic administration of ethanol. The microsomal cytochrome P-450 content also tended to slightly increase in the same strains of mice. It seemed that cytochrome P-450IIE1 was induced in the liver microsomes of these strains. Total aldehyde dehydrogenase (ALDH) activities together with high-Km ALDH activity increased markedly in the microsomes of C57BL mice and tended to increase in C3H/He mice, while it did not change in DBA mice following chronic ethanol administration. In the mitochondria of C57BL, total ALDH activities increased slightly and high-Km ALDH activities tended to increase. These mitochondrial ALDH activities of C3H/He and DBA mice tended to increase following chronic ethanol administration. The cytosolic ALDH activity showed no changes in any strain of mice following chronic ethanol administration. It seemed that in the microsomes, the activities of enzymes related to oxidation of ethanol increased in C57BL and C3H/He mice, which tended to consume a large amount of ethanol, and did not in DBA mice which tended to consume a small amount of it. It seemed that the increases in activities of enzymes related to oxidation of acetaldehyde in the microsomes and in the mitochondria were responsible for the strain difference.     

Role of glutathione in hepatic bile formation during reperfusion after cold ischemia of the rat liver

BACKGROUND/AIMS: Liver reperfusion following cold ischemia is frequently associated with diminished bile flow in patients undergoing liver transplantation. Glutathione is a major determinant of bile-acid independent bile flow, and the effects of cold ischemia on biliary glutathione excretion are unknown. METHODS: We examined the effects of cold ischemia (University of Wisconsin solution (4 degrees C), 24 h) with subsequent reperfusion (100 min) on biliary glutathione excretion in a recirculating system. Since glutathione might represent an important antioxidant within the biliary tract and oxidative stress in the biliary tract during reperfusion could contribute to the pathogenesis of bile duct injury after liver transplantation, we also assessed bile duct morphology in reperfused livers of mutant TR- -rats, in whom biliary excretion of glutathione is already impaired. RESULTS: Hepatic bile formation was diminished in reperfused Wistar rat livers after cold ischemia. Biliary glutathione concentrations and output were significantly decreased and correlated with postischemic changes in bile secretion. An increased biliary oxidized glutathione/glutathione ratio, indicating oxidative stress, was detected only immediately after the onset of reperfusion. Basal bile flow rates in TR- -rat livers which were already markedly reduced in control-perfused livers, decreased further during the early but not the later reperfusion period. Reperfusion of both Wistar and TR- -rat livers was not associated with electron microscopic evidence of bile duct damage. CONCLUSIONS: We conclude that impaired biliary excretion of glutathione contributes to decreased bile flow after cold ischemia. The absence of biliary glutathione does not appear to promote ultrastructural evidence of bile duct injury during reperfusion in the isolated perfused rat liver.     

Protective effects of API0134 on myocardial ischemia and reperfusion injury

A rare case of gangrenous cystitis is described. The questions of the incidence of this pathology are discussed, considering its rareness after the antibiotics age. The etiology of this disease is probably multifactorial and it is never possible to identify a unique cause. The gangrenous cystitis doesn't present with any typical symptomatology, out with urinary troubles common to many urologic diseases. Surgery is often performed in emergency without a preoperative defined diagnosis. Surgical treatment has changed with time from a simple bladder cavity draining to the resection of the necrotized bladder wall. In our case a total cystectomy with uretero-ileocutaneostomy, in two times, was performed. This procedure allowed the patient a good quality of life (1 year of follow-up).     

Anti-selectin therapy modifies skeletal muscle ischemia and reperfusion injury

Restoration of blood flow to ischemic skeletal muscle results in a reperfusion injury characterized by permeability edema in part mediated by neutrophils that adhere via the selectin family of adhesion molecules. Rats underwent 4 h of hindlimb tourniquet ischemia followed by 4 h reperfusion. The role of neutrophils was determined by rendering one group of animals neutropenic before ischemia. In additional experimental groups, selectins were blocked with either a soluble form of the selectin counter-receptor, sialyl-Lewis X (SLX) or a monoclonal antibody directed against P-selectin (PB1.3). Neutrophil depletion resulted in a 36.1% reduction in hindlimb permeability (p < .05). SLX reduced hindlimb permeability index (PI) 23.9% at 1 mg/kg and 36.1% at 10 mg/kg compared to a nonfucosylated oligosaccharide, sialyl-N-acetylactosamine (p < .05). SLX also reduced neutrophil sequestration by 48.6% (p < .05). PB1.3 reduced hindlimb injury by 26.5% (p < .05) but did not reduce leukosequestration. We interpret these data to indicate that ischemia and reperfusion lead to selectin-mediated neutrophil sequestration. The oligosaccharide SLX, while moderately effective in limiting neutrophil sequestration was as effective as neutrophil depletion in reducing hindlimb permeability. The lack of concordance between the ability of SLX and PB1.3 in limiting neutrophil sequestration and permeability indicate mechanisms of action of these two agents that are in addition to the blocking of adhesion.