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C Thiemermann

Publications and source records attributed to C Thiemermann.

At least 55 records · Page 3Linked to original sources
PubMed2000

Inhibitors of poly (ADP-ribose) synthetase reduce renal ischemia-reperfusion injury in the anesthetized rat in vivo.

The activation of poly (ADP-ribose) synthetase (PARS) subsequent to DNA damage caused by reactive oxygen or nitrogen species has been implicated in several pathophysiological conditions, including ischemia-reperfusion injury and shock. The aim of this study was to investigate whether PARS inhibitors could provide protection against renal ischemia-reperfusion injury in the rat in vivo. Male Wistar rats were subjected to 45 min bilateral clamping of the renal pedicles, followed by 6 h reperfusion (control animals). Animals were administered the PARS inhibitors 3-aminobenzamide, 1, 5-dihydroxyisoquinoline, or nicotinamide during the reperfusion period. Ischemia, followed by reperfusion, produced significant increases in plasma concentrations of urea, creatinine, and fractional excretion of Na(+) (FE(Na)) and produced a significant reduction in glomerular filtration rate (GFR). However, administration of the PARS inhibitors significantly reduced urea and creatinine concentrations, suggesting improved renal function. The PARS inhibitors also significantly increased GFR and reduced FE(Na), suggesting the recovery of both glomerular and tubular function, respectively, with a more pronounced recovery of tubular function. In kidneys from control animals, histological examination revealed severe renal damage and immunohistochemical localization demonstrated PARS activation in the proximal tubule. Both renal damage and PARS activation were attenuated by administration of PARS inhibitors during reperfusion. Therefore, we propose that PARS activation contributes to renal reperfusion injury and that PARS inhibitors may be beneficial in renal disorders associated with oxidative stress-mediated injury.

Anesthesia↗
PubMed2000

Membrane-permeable radical scavenger, tempol, reduces multiple organ injury in a rodent model of gram-positive shock.

OBJECTIVE: An enhanced formation of reactive oxygen species contributes to the multiple organ dysfunction syndrome (MODS) caused by endotoxin. We have recently discovered that two cell wall components, namely lipoteichoic acid (LTA) and peptidoglycan (PepG) of the gram-positive bacterium, Staphylococcus aureus, synergize to cause shock and MODS in the rat. Here, we investigate the effects of a membrane-permeable radical scavenger (tempol) on the circulatory failure and MODS (kidney, liver, lung) caused by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) in the anesthetized rat. DESIGN: Prospective, randomized study. SETTING: University-based research laboratory. SUBJECTS: Thirty-four anesthetized, male Wistar rats. INTERVENTIONS: After surgical preparation, anesthetized rats were observed for 6 hrs. Control rats were given vehicle (control plus saline, 2 mL/kg bolus injection, followed by an infusion of 1.5 mL/kg i.v., n = 6) or tempol (control plus tempol, 100 mg/kg i.v. bolus injection, followed by an infusion of 30 mg/kg i.v., n = 6). Gram-positive septic shock was induced by coadministration of LTA (3 mg/kg i.v.) and PepG (10 mg/kg i.v.) (LTA/PepG plus saline, n = 12). Another group of rats was pretreated with tempol before shock was induced (LTA/PepG plus tempol, 100 mg/kg i.v. bolus injection, 15 mins before LTA/PepG administration, followed by an infusion of 30 mg/kg i.v., n = 10). MEASUREMENTS AND MAIN RESULTS: Within 6 hrs, administration of LTA/PepG resulted in hypotension, acute renal dysfunction, hepatocellular injury, pancreatic injury, and increased plasma concentrations of nitrite/nitrate. Pretreatment of rats with tempol augmented the hypotension but attenuated the renal dysfunction and the hepatocellular injury/dysfunction caused by LTA/PepG. Tempol did not affect the increase in nitrite/nitrate caused by LTA/PepG. CONCLUSIONS: These results imply that an enhanced formation of reactive oxygen species (including superoxide anions) contributes to the kidney and liver injury and dysfunction caused by LTA/PepG in the anesthetized rat.

Animals↗
PubMed2000

Beneficial effects of tempol, a membrane-permeable radical scavenger, in a rodent model of splanchnic artery occlusion and reperfusion.

The aim of the present study was to investigate the effects of tempol, a membrane-permeable radical scavenger, in rats subjected to splanchnic artery occlusion shock (SAO). Rats subjected to SAO developed a significant decrease in mean arterial blood pressure, a significant increase in tissue myeloperoxidase activity, and a marked injury to the distal ileum. SAO shock resulted in 100% mortality at 2 h after reperfusion. At 60 min after reperfusion, a marked increase in the immunoreactivity to nitrotyrosine and to poly (ADP-ribose) synthetase was observed in the necrotic ileum of rats with SAO. Staining of sections of the ileum obtained from SAO-shocked rats with anti-intercellular adhesion molecule (ICAM-1) and anti-P-selectin antibodies resulted in diffuse staining. Tempol (30 mg/kg bolus injection 5 min prior to reperfusion, followed by an infusion of 30 mg/kg/h intravenously) attenuated 1) the infiltration of the reperfused intestine with neutrophils, 2) the lipid peroxidation, 3) the production of peroxynitrite, 4) the degree of P-selectin and ICAM-1 staining in tissue sections from SAO-shocked rats, 5) histological signs of bowel injury, and 6) mortality at 2 h after reperfusion. Taken together, our results clearly demonstrate that the intracellular radical scavenger tempol reduces the intestinal injury of rats subjected SAO shock.

Animals↗
PubMed2000

Peptidoglycan and lipoteichoic acid from Staphylococcus aureus induce tumor necrosis factor alpha, interleukin 6 (IL-6), and IL-10 production in both T cells and monocytes in a human whole blood model.

We have examined the ability of peptidoglycan (PepG) and lipoteichoic acid (LTA) isolated from Staphylococcus aureus to induce the release of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and IL-10 in whole human blood and identified the cellular origins of these cytokines. Both PepG and LTA induced transient increases in TNF-alpha and IL-10 in plasma, with peak values at 6 and 12 h, respectively. IL-6 values increased throughout the experimental period (24 h). The TNF-alpha, IL-6, and IL-10 release induced by PepG and LTA was dose dependent. Only PepG was a potent inducer of TNF-alpha secretion. After stimulation of whole blood with PepG or LTA, very pure populations of monocytes (CD14 positive), T cells (CD2 positive), B cells (CD19 positive), and granulocytes (CD15 positive) were isolated by immunomagnetic separation and analyzed by reverse transcription-PCR for mRNA transcripts encoding TNF-alpha, IL-6, and IL-10. The TNF-alpha mRNA results were inconclusive. In contrast, PepG induced IL-6 and IL-10 mRNA accumulation in both T cells and monocytes. LTA, as well as lipopolysaccharide, induced IL-6 and IL-10 mRNA production in monocytes and possibly in T cells. Whether granulocytes and B cells produce cytokines in response to bacterial stimuli remains obscure. Blockade of the CD14 receptors with monoclonal antibodies (18D11) had no influence on the PepG-induced release of TNF-alpha but attenuated the LTA-induced release of the same cytokine. In conclusion, our data indicate that circulating T cells and monocytes contribute to cytokine production in sepsis caused by gram-positive bacteria.

Cytokines↗
PubMed2000

Lipoteichoic acid induces delayed protection in the rat heart: A comparison with endotoxin.

Classic ischemic preconditioning transiently (30 to 120 minutes) protects the myocardium against subsequent lethal ischemia/reperfusion injury. After dissipation of this acute protection, a second window of protection (SWOP) appears 12 to 24 hours later; this SWOP lasts up to 3 days. Several triggers induce a SWOP, including brief repetitive cycles of coronary artery occlusion, rapid ventricular pacing, stimulation of adenosine A(1) receptors, and administration of wall fragments of Gram-negative bacteria, such as lipopolysaccharide (LPS). The aim of this study was to investigate whether lipoteichoic acid (LTA), a cell wall fragment of Gram-positive bacteria, can induce a SWOP in a rat model of left anterior descending coronary artery (LAD) occlusion (25 minutes) and reperfusion (2 hours). Thus, 166 male Wistar rats were pretreated (2 to 24 hours) with saline, LTA (1 mg/kg IP), or LPS (1 mg/kg IP) and subjected to LAD occlusion/reperfusion. Pretreatment with LTA or LPS for 16 hours led to a substantial, approximately 65%, reduction in infarct size and a reduction in the release of cardiac troponin T into the plasma. The dose of LTA used had no toxic effect (on any of the parameters studied), whereas the same dose of LPS caused a time-dependent activation of the coagulation system and liver injury. By use of RNase protection assays, it was determined that LPS caused a time-dependent induction of tumor necrosis factor-alpha, interleukin-1beta, and manganese superoxide dismutase mRNA content in the heart, whereas LTA failed to induce manganese superoxide dismutase. LPS also caused an upregulation of the expression of intercellular adhesion molecule-1 and P-selectin, whereas LTA downregulated these molecules and attenuated the accumulation of polymorphonuclear granulocytes caused by myocardial ischemia/reperfusion. This study demonstrates for the first time that pretreatment with LTA at 8 to 24 hours before myocardial ischemia significantly reduces (1) infarct size, (2) cardiac troponin T, and (3) the histological signs of tissue injury in rats subjected to LAD occlusion and reperfusion. The mechanism(s) underlying the observed cardioprotective effects of LTA warrants further investigation but is likely to be related to its ability to inhibit the interactions between the coronary vascular endothelium and polymorphonuclear granulocytes. Therefore, LTA represents a novel and promising agent capable of enhancing myocardial tolerance to ischemia/reperfusion injury.

Animals↗
PubMed1999

Role of IL-6 in the pleurisy and lung injury caused by carrageenan.

In the present study we used IL-6 knockout mice (IL-6KO) to evaluate the role of IL-6 in the inflammatory response caused by injection of carrageenan into the pleural space. Compared with carrageenan-treated IL-6 wild-type (IL-6WT) mice, carrageenan-treated IL-6KO mice exhibited a reduced degree of pleural exudation and polymorphonuclear cell migration. Lung myeloperoxidase activity and lipid peroxidation were significantly reduced in IL-6KO mice compared with those in IL-6WT mice treated with carrageenan. Immunohistochemical analysis for nitrotyrosine and poly(A)DP-ribose polymerase revealed a positive staining in lungs from carrageenan-treated IL-6WT mice. No positive staining for nitrotyrosine or PARS was found in the lungs of the carrageenan-treated IL-6KO mice. Staining of lung tissue sections obtained from carrageenan-treated IL-6WT mice with an anti-cyclo-oxygenase-2 Ab showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in the macrophages of the inflamed lungs from carrageenan-treated IL-6WT mice. The intensity and degree of the staining for cyclo-oxygenase-2 and inducible nitric oxide synthase were markedly reduced in tissue sections obtained from carrageenan-treated IL-6KO mice. Most notably, the degree of lung injury caused by carrageenan was also reduced in IL-6KO mice. Treatment of IL-6WT mice with anti-IL-6 (5 microg/day/mouse at 24 and 1 h before carrageenan treatment) also significantly attenuated all the above indicators of lung inflammation. Taken together, our results clearly demonstrate that IL-6KO mice are more resistant to the acute inflammation of the lung caused by carrageenan injection into the pleural space than the corresponding WT mice.

Animals↗
PubMed1999

Reduction of myocardial injury by the EP3 receptor agonist TEI-3356. Role of protein kinase C and of K(ATP)-channels.

The effects of the prostanoid EP3 receptor agonist TEI-3356 on either protein kinase C or ATP-sensitive (K(ATP)) K+ channels and on the infarct size caused by regional myocardial ischaemia and reperfusion in the rat were investigated. Male Wistar rats (n = 72) were subjected to 25 min occlusion of the left anterior descending coronary artery followed by 2 h of reperfusion. TEI-3356 (1 microg/kg/min i.v., n = 6) caused a significant reduction in infarct size from 60+/-3% (control, n = 8) to 38+/-3% of the area at risk. Pretreatment of rats with 5-hydroxydecanoate (5 mg/kg i.v., n = 6), a specific inhibitor of K(ATP)-channels, attenuated the cardioprotective effects of TEI-3356. The reduction in infarct size afforded by TEI-3356 was also abolished by the protein kinase C inhibitors staurosporine (1 microg/kg i.v., n = 6) and chelerythrine (0.7 mg/kg i.v., n = 5). Thus, TEI-3356 reduces myocardial infarct size in the rat by a mechanism(s) which involves the activation of protein kinase C and the opening of K(ATP)-channels.

Adenosine Triphosphate↗
PubMed1999

Inhibitors of poly (ADP-ribose) synthetase protect rat cardiomyocytes against oxidant stress.

OBJECTIVE: Inhibitors of poly (ADP-ribose) synthetase (PARS) activity reduce the infarct size caused by regional myocardial ischaemia and reperfusion in the rabbit and rat in vivo. The mechanism of action of these inhibitors is unclear. Here we investigate the effects of the PARS inhibitor 3-aminobenzamide (3-AB) on infarct size caused by ischaemia and reperfusion of the isolated, perfused heart of the rat. We also investigate the role of PARS in the hydrogen peroxide-mediated cell injury/necrosis in rat cardiac myoblasts. METHODS: Rat isolated hearts perfused at constant pressure (80 mmHg) were subjected to 35 min of regional ischaemia and 2 h of reperfusion. Infarct size was determined at the end of the experiment using nitro-blue tetrazolium. 3-AB (300 microM) or 3-aminobenzoic acid (3-ABA, 300 microM) were infused during the reperfusion period. Rat cardiac myoblasts (H9c2 cells) were preincubated with the PARS inhibitors, 3-AB. nicotinamide (Nic) or 1,5-dihydroxyisoquinoline (ISO) or the inactive analogues 3-ABA or nicotinic acid (NicA) prior to exposure with hydrogen peroxide (1 mM). Cell injury was assessed by measuring mitochondrial respiration and cell necrosis by measuring the release of LDH. PARS activity was determined by measuring the incorporation of NAD into nuclear proteins. RESULTS: Regional ischaemia and reperfusion of the isolated rat heart resulted in an infarct size of 54% which was reduced by 3-AB, but not by 3-ABA. Exposure of rat cardiac myoblasts to hydrogen peroxide caused an increase in PARS activity and cell injury/necrosis which was attenuated by pretreatment with the PARS inhibitors. CONCLUSION: Inhibition of the activity of PARS attenuates the cell death associated with oxidant stress in rat cardiac myoblasts and heart.

Aminobenzoates↗
PubMed1999

Tempol reduces infarct size in rodent models of regional myocardial ischemia and reperfusion.

Reactive oxygen species (ROS) contribute to ischemia-reperfusion injury of the heart. This study investigates the effects of tempol, a membrane-permeable radical scavenger on (i) the infarct size caused by regional myocardial ischemia and reperfusion of the heart in vivo (rat, rabbit) and in vitro (rat), and (ii) the cell injury caused by hydrogen peroxide (H2O2) in rat cardiac myoblasts (H9c2 cells). In the anesthetized rat, tempol reduced the infarct size caused by regional myocardial ischemia (25 min) and reperfusion (2 h) from 60 +/- 3% (control, n = 8) to 24 +/- 5% (n = 6, p < .05). In the anesthetized rabbit, tempol also attenuated the infarct size caused by myocardial ischemia (45 min) and reperfusion (2 h) from 59 +/- 3% (control, n = 6) to 39 +/- 5% (n = 5, p < .05). Regional ischemia (35 min) and reperfusion (2 h) of the isolated, buffer-perfused heart of the rat resulted in an infarct size of 54 +/- 4% (control n = 7). Reperfusion of hearts with buffer containing tempol (n = 6) caused a 37% reduction in infarct size (n = 6, p < .05). Pretreatment of rat cardiac myoblasts with tempol attenuated the impairment in mitochondrial respiration caused by H2O2 (1 mM for 4 h). Thus, the membrane-permeable radical scavenger tempol reduces myocardial infarct size in rodents.

Animals↗
PubMed1999

Effects of the prostanoid EP3-receptor agonists M&B 28767 and GR 63799X on infarct size caused by regional myocardial ischaemia in the anaesthetized rat.

1. This study investigates the effects of two agonists of the prostanoid EP3-receptor (M&B 28767 and GR 63799X) on the infarct size caused by regional myocardial ischaemia and reperfusion in the anaesthetized rat. 2. One hundred and sixty-seven, male Wistar rats were anaesthetized (thiopentone, 120 mg kg(-1) i.p.), ventilated (8-10 ml kg(-1), 70 strokes min(-1), inspiratory oxygen concentration: 30%; PEEP: 1-2 mmHg) and subjected to occlusion of the left anterior descending coronary artery (LAD, for 7.5, 15, 25, 35, 45 or 60 min) followed by reperfusion (2 h). Infarct size was determined by staining of viable myocardium with a tetrazolium stain (NBT), histological evaluation by light and electron microscopy and determination of the plasma levels of cardiac troponin T. 3. M&B 28767 (0.5 microg kg(-1) min(-1), i.v., n=7) or GR 63799X (3 microg kg(-1) min(-1), i.v., n=7) caused significant reductions in infarct size from 60+/-3% (25 min ischaemia and 2 h reperfusion; saline-control, n=8) to 39+/-6 and 38+/-4% of the area at risk, without causing a significant fall in blood pressure. Pretreatment of rats with 5-hydroxydecanoate (5-HD), an inhibitor of ATP-sensitive potassium channels, attenuated the cardioprotective effects of both EP3-receptor agonists. The reduction in infarct size afforded by M&B 28767 was also abolished by glibenclamide and the protein kinase C (PKC) inhibitors staurosporine and chelerythrine. 4. Thus, M&B 28767 and GR 63799X reduce myocardial infarct size in the rat by a mechanism(s) which involves the activation of PKC and the opening of ATP-sensitive potassium channels.

Alprostadil↗
PubMed1999

An inhibitor of poly (ADP-ribose) synthetase activity reduces contractile dysfunction and preserves high energy phosphate levels during reperfusion of the ischaemic rat heart.

The cardioprotective properties of inhibition of poly (ADP-ribose) synthetase (PARS) were investigated in the isolated perfused heart of the rat. Hearts were perfused in the Langendorff mode and subjected to 23 min total global ischaemia and reperfused for 60 min. Left ventricular function was assessed by means of an intra-ventricular balloon. High energy phosphates were measured by 31P-NMR spectroscopy. Intracellular levels of NAD were measured by capillary electrophoresis of perchloric acid extracts of hearts at the end of reperfusion. Reperfusion in the presence of the PARS inhibitor 1,5 didroxyisoquinoline (ISO, 100 microM) attenuated the mechanical dysfunction observed following 1 h of reperfusion; 27+/-13 and 65+/-8% recovery of preischaemic rate pressure product for control and 100 microM ISO, respectively. This cardioprotection was accompanied by a preservation of intracellular high-energy phosphates during reperfusion; 38+/-2 vs 58+/-4% (P<0.05) of preischaemic levels of phosphocreatine (PCr) for control and 100 microM ISO respectively and 23+/-1 vs 31+/-3% (P < 0.05) of preischaemic levels of ATP for control and 100 microM ISO respectively. Cellular levels of NAD were higher in ISO treated hearts at the end of reperfusion; 2.56+/-0.45 vs 4.76+/-1.12 micromoles g(-1) dry weight (P<0.05) for control and ISO treated. These results demonstrate that the cardioprotection afforded by inhibition of PARS activity with ISO is accompanied by a preservation of high-energy phosphates and cellular NAD levels and suggest that the mechanism responsible for this cardioprotection may involve prevention of intracellular ATP depletion.

Adenosine Triphosphate↗
PubMed1999

Reduction of myocardial infarct size with sCR1sLe(x), an alternatively glycosylated form of human soluble complement receptor type 1 (sCR1), possessing sialyl Lewis x.

1 This study investigated the effects of soluble complement receptor type 1 (sCR1) or sCR1sLex, agents which function as a complement inhibitor or as a combined complement inhibitor and selectin adhesion molecule antagonist, respectively, on the infarct size and cardiac troponin T (cTnT) release caused by regional myocardial ischaemia and reperfusion in the rat. 2 Eighty-two, male Wistar rats were subjected to 30 min occlusion of the left anterior descending coronary artery (LAD) followed by 2 h of reperfusion. Haemodynamic parameters were continuously recorded and at the end of the experiments infarct size (with p-nitro-blue tetrazolium) and cTnT release were determined. 3 Infusion of sCR1 (1, 5 or 15 mg kg-1, each n=7) or sCR1sLe(x) (1, 5 or 15 mg kg-1, n=7, 13 or 13, respectively) 5 min prior to LAD-reperfusion caused a reduction in infarct size from 59+/-2% (PBS - control, n=12) to 46+/-6%, 25+/-9% and 37+/-6% or 42+/-6%, 35+/-6% and 35+/-4%, respectively. 4 Infusion of sCR1 (15 mg kg-1, n=5) or sCR1sLe(x) (15 mg kg-1, n=5) also reduces the myocardial TnT release from 80+/-20 ng ml-1 (control) to 13+/-7 or 4+/-1 ng ml-1, respectively. 5 Thus, sCR1 or sCRsLe(x) significantly reduce infarct size and cardiac TnT release caused by 30 min of regional myocardial ischaemia and 2 h of reperfusion in the rat. The mechanisms of the cardioprotective effects of sCR1 or sCR1sLe(x) are not entirely clear, but may be due complement inhibition and/or prevention of the adhesion and activation of neutrophils.

Animals↗
PubMed1999

Effects of inhibitors of the activity of poly (ADP-ribose) synthetase on the organ injury and dysfunction caused by haemorrhagic shock.

1 Poly (ADP-ribose) synthetase (PARS) is a nuclear enzyme activated by strand breaks in DNA, which are caused by reactive oxygen species (ROS). Here we investigate the effects of the PARS inhibitors 3-aminobenzamide (3-AB), nicotinamide and 1,5-dihydroxyisoquinoline (ISO) on the circulatory failure and the organ injury/dysfunction caused by haemorrhage and resuscitation in the anaesthetized rat. 2 Haemorrhage (sufficient to lower mean arterial blood pressure to 50 mmHg for 90 min) and subsequent resuscitation with shed blood resulted (within 4 h after resuscitation) in a delayed fall in blood pressure to 66+/-4 mmHg (control, n=13). This circulatory failure was not affected by administration (5 min prior to resuscitation) of 3-AB (10 mg kg-1 i.v., n=7), nicotinamide (10 mg kg-1 i.v., n=6) or ISO (3 mg kg-1 i.v., n=6). 3 Haemorrhage and resuscitation also resulted in rises in the serum levels of urea and creatinine. This renal dysfunction was attenuated by 3-AB and nicotinamide, but not by nicotinic acid (n=7), an inactive analogue of nicotinamide. Although ISO (n=6) also attenuated the renal dysfunction caused by haemorrhage and resuscitation, its vehicle (10% DMSO, n=4) had the same effect. 4 Haemorrhagic shock resulted in enhanced serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lipase, indicating the development of hepatocellular and pancreatic injury, respectively. Similarly, haemorrhagic shock also resulted in an increase in the serum levels of creatine kinase (CK) indicating the development of neuromuscular injury. This was attenuated by 3-AB and nicotinamide, but not by nicotinic acid. Although ISO also attenuated the liver, pancreatic and neuromuscular injury caused by haemorrhagic shock, its vehicle had the same effect. 5 Thus, activation of PARS contributes to the organ injury and dysfunction caused by haemorrhage and resuscitation in the rat.

Alanine Transaminase↗
PubMed1999

Inhibitors of poly (ADP-ribose) synthetase protect rat proximal tubular cells against oxidant stress.

BACKGROUND: The generation of reactive oxygen species (ROS) has been implicated in the pathogenesis of renal ischemia-reperfusion injury. ROS produce DNA strand breaks that lead to the activation of the DNA-repair enzyme poly (ADP-ribose) synthetase (PARS). Excessive PARS activation results in the depletion of its substrate, nicotinamide adenine dinucleotide (NAD) and subsequently of adenosine 5'-triphosphate (ATP), leading to cellular dysfunction and eventual cell death. The aim of this study was to investigate the effect of various PARS inhibitors on the cellular injury and death of rat renal proximal tubular (PT) cells exposed to hydrogen peroxide (H2O2). METHODS: Rat PT cell cultures were incubated with H2O2 (1 mM) either in the presence or absence of the PARS inhibitors 3-aminobenzamide (3-AB, 3 mM), 1,5-dihydroxyisoquinoline (0.3 mM) or nicotinamide (Nic, 3 mM), or increasing concentrations of desferrioxamine (0.03 to 3 mM) or catalase (0.03 to 3 U/ml). Cellular injury and death were determined using the MTT and lactate dehydrogenase (LDH) assays, respectively. H2O2-mediated PARS activation in rat PT cells and the effects of PARS inhibitors on PARS activity were determined by measurement of the incorporation of [3H]NAD into nuclear proteins. RESULTS: Incubation of rat PT cells with H2O2 significantly inhibited mitochondrial respiration and increased LDH release, respectively. Both desferrioxamine and catalase reduced H2O2-mediated cellular injury and death. All three PARS inhibitors significantly attenuated the H2O2-mediated decrease in mitochondrial respiration and the increase in LDH release. Incubation with H2O2 produced a significant increase in PARS activity that was significantly reduced by all PARS inhibitors. 3-Aminobenzoic acid (3 mM) and nicotinic acid (3 mM), structural analogs of 3-AB and Nic, respectively, which did not inhibit PARS activity, did not reduce the H2O2-mediated injury and necrosis in cultures of rat PT cells. CONCLUSION: We propose that PARS activation contributes to ROS-mediated injury of rat PT cells and, therefore, to the cellular injury and cell death associated with conditions of oxidant stress in the kidney.

Animals↗
PubMed1999

Upregulation of ICAM-1 expression on J774.2 macrophages by endotoxin involves activation of NF-kappaB but not protein tyrosine kinase: comparison to induction of iNOS.

This study compares the signal transduction pathway which leads to the upregulation of intercellular adhesion molecule-1 (ICAM-1) expression with that of the increase in the expression of inducible nitric oxide synthase (iNOS) protein and activity caused by endotoxin in cultured J774.2 macrophages. Treatment of J774.2 cells with lipopolysaccharide E. coli (LPS) induced a concentration-dependent increase in the expression of ICAM-1 on the cell surface within 4 h and an increase in iNOS protein and activity at 24 h. The upregulation of ICAM-1 expression on J774.2 macrophages caused by LPS was significantly inhibited by pretreatment of the cells with inhibitors of the activation of the nuclear transcription factor NF-kappaB, such as L-1-tosylamido-2-phenylethylchloromethyl ketone (TPCK), pyrrolidine dithiocarbamate (PDTC), rotenone or calpain inhibitor I, but not by the tyrosine kinase inhibitors, tyrphostin AG126 or genistein. In contrast, genistein or tyrphostin AG126 also prevented the induction of iNOS protein and activity in J774.2 macrophages elicited by LPS. Thus, the increase in the expression of ICAM-1 on J774.2 macrophages by endotoxin involves the activation of NFkappaB, but not of protein tyrosine kinase.

Animals↗
PubMed1999

Identification of copper/zinc superoxide dismutase as a novel nitric oxide-regulated gene in rat glomerular mesangial cells and kidneys of endotoxemic rats.

To define the mechanism of nitric oxide (NO) action in the glomerulus, we attempted to identify genes that are regulated by NO in rat glomerular mesangial cells. We identified a Cu/Zn superoxide dismutase (SOD) that was strongly induced in these cells by treatment with S-nitroso-glutathione as a NO-donating agent. Bacterial lipopolysaccharide (LPS) acutely decreased Cu/Zn SOD mRNA levels. The LPS-mediated decrease in Cu/Zn SOD is reversed by endogenously produced NO, as LPS also induced a delayed strong iNOS expression in these cells in vitro, which is accompanied by increased Cu/Zn SOD expression. NO dependency of Cu/Zn SOD mRNA recovery could be demonstrated by inhibition of this process by L-NG-monomethylarginine, an inhibitor of NOS enzymatic activity. To demonstrate the in vivo relevance of our observations, we have chosen LPS-treated rats as a model for induction of a systemic inflammatory response. In these animals, we demonstrate a direct coupling of Cu/Zn SOD expression levels to the presence of NO, as Cu/Zn SOD mRNA levels declined during acute inflammation in the presence of a selective inhibitor of iNOS. We propose that the up-regulation of Cu/Zn SOD by endogenous NO may serve as an adaptive, protective mechanism to prevent the formation of toxic quantities of peroxynitrite in conditions associated with iNOS induction during endotoxic shock.

Animals↗
PubMed1999

A membrane-permeable radical scavenger reduces the organ injury in hemorrhagic shock.

Reactive oxygen species (ROS) contribute to the multiple organ failure (MOF) in hemorrhagic shock. Here we investigate the effects of a membrane-permeable radical scavenger (tempol) on the circulatory failure and the organ injury and dysfunction (kidney, liver, lung, intestine) associated with hemorrhagic shock in the anesthetized rat. Hemorrhage (sufficient to lower mean arterial blood pressure to 500 mmHg for 90 min) and subsequent resuscitation with shed blood resulted (within 4 h after resuscitation) in a delayed fall in blood pressure, renal and liver injury and dysfunction as well as lung and gut injury. In all organs, hemorrhage and resuscitation resulted in the nitrosylation of proteins (determined by immunohistochemistry for nitrotyrosine) suggesting the formation of peroxynitrite and/or reactive oxygen species. Treatment of rats upon resuscitation with the membrane-permeable radical scavenger tempol (30 mg/kg bolus injection followed by an infusion of 30 mg/kg/h i.v.) attenuated the delayed circulatory failure as well as the multiple organ injury and dysfunction associated with hemorrhagic shock. Thus, we propose that an enhanced formation of ROS and/or peroxynitrite importantly contributes to the MOF in hemorrhagic shock, and that membrane-permeable radical scavengers, such as tempol, may represent a novel therapeutic approach for the therapy of hemorrhagic shock.

Animals↗