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Biomedical subjects

C Thiemermann

Publications and source records attributed to C Thiemermann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Beneficial effects of tempol, a membrane-permeable radical scavenger, on the multiple organ failure induced by zymosan in the rat.

BACKGROUND AND METHODS: We investigated the effects of tempol, a membrane-permeable radical scavenger, on the multiple organ failure (MOF) caused by zymosan in the rat. Zymosan (500 mg/kg, suspended in saline solution, ip) enhances formation of reactive oxygen species, which contribute to the pathophysiology of MOF. After zymosan or saline administration, animals were monitored for 12 days. RESULTS: Treatment of rats with tempol (10, 30, or 100 mg/kg ip, 1 and 6 hrs after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan in a dose-dependent fashion. Tempol also attenuated the lung, liver, and intestinal injury (histology) as well as the increase in the concentrations of myeloperoxidase and malondialdehyde caused by zymosan in the lung, liver, and intestine. Immunohistochemical analysis for nitrotyrosine and for poly(adenosine 5'-diphosphate-ribose)synthetase demonstrated a positive staining in lung, liver, and intestine from zymosan-treated rats. The degree of staining for nitrotyrosine and for poly(adenosine 5'-diphosphate-ribose) synthetase was markedly reduced in tissue sections obtained from zymosan-treated rats that had received tempol (100 mg/kg ip). Furthermore, treatment of rats with tempol significantly reduced the following: a) the formation of peroxynitrite, b) the DNA damage, c) the impairment in mitochondrial respiration, and d) the decrease in the cellular concentration of oxidized nicotinamide adenine dinucleotide observed in macrophages harvested from the peritoneal cavity of rats treated with zymosan. CONCLUSION: This study provides the first evidence that tempol, a small molecule that permeates biological membranes and scavenges reactive oxygen species, attenuates the degree of MOF associated with zymosan-induced peritonitis in the rat.

Analysis of Variance↗
PubMed2001

The selective guanylate cyclase inhibitor ODQ reduces multiple organ injury in rodent models of Gram-positive and Gram-negative shock.

OBJECTIVE: An enhanced formation of endogenous nitric oxide contributes to the circulatory failure caused by endotoxin (lipopolysaccharide). Many of the biological actions of nitric oxide are mediated by the guanylate cyclase/cyclic guanosine 3prime;,5'-monophosphate system. We recently discovered that two cell wall components, namely lipoteichoic acid and peptidoglycan of the Gram-positive bacterium Staphylococcus aureus, synergize to cause shock and multiple organ dysfunction syndrome in the rat. Here we investigate the effects of a selective guanylate cyclase inhibitor, 1H-(1,2,4)oxadiazole(4,3-alpha)quinoxaline-1-one (ODQ), on the circulatory failure and multiple organ dysfunction syndrome (kidney, liver, lung) caused by a) coadministration of lipoteichoic acid and peptidoglycan (Gram-positive shock) or b) lipopolysaccharide (Gram-negative shock) in the anesthetized rat. Furthermore, we investigated whether ODQ scavenges superoxide anions and/or hydroxyl radicals. DESIGN: The in vivo portion of the study was a prospective, randomized, controlled animal study. The in vitro portion included a) cultured ventricular myoblasts of the rat, H9c2(2-1) cells, and b) a cell free superoxide anion assay system. SETTING: University-based research laboratory. SUBJECTS: Seventy-five anesthetized, male Wistar rats were used for the in vivo study. INTERVENTIONS: For the in vivo portion of the study, after surgical preparation, anesthetized rats were observed for 6 hrs. All rats were pretreated and received an intravenous infusion of saline (1.5 mL.kg-1.hr-1), which was maintained throughout the experiment. The rats were assigned to nine groups. Group 1 contained control rats (sham) subjected to 2 mL/kg saline intraperitoneally, 2 hrs before the experiment (n = 7). Group 2 contained control rats (sham) that received 2 mg/kg ODQ intraperitoneally, 2 hrs before the experiment (n = 9). Group 3 contained control rats (sham) that received 2 mL/kg dimethyl sulfoxide, 30% v/v in saline intraperitoneally, as a vehicle for ODQ, 2 hrs before the experiment (n = 6). In group 4 rats, Gram-positive shock was induced by coadministration of lipoteichoic acid (3 mg/kg intravenously) and peptidoglycan (10 mg/kg intravenously) (n = 10). In group 5, rats were pretreated with ODQ (as described previously) before lipoteichoic acid/peptidoglycan (n = 9). In group 6, rats were pretreated with dimethyl sulfoxide (as described previously) before lipoteichoic acid/peptidoglycan (n = 7). In group 7, Gram-negative shock was induced by lipopolysaccharide (6 mg/kg intravenously) (n = 11). In group 8, rats were pretreated with ODQ (as described previously) before lipopolysaccharide (n = 8). In group 9, rats were pretreated with dimethyl sulfoxide (as described previously) before lipopolysaccharide (n = 8). For the in vitro portion of the study, rat cells were preincubated with vehicle (saline and/or dimethyl sulfoxide) and ODQ (0.1 microM to 1 mM) for 2 hrs. The cells then were exposed to H2O2 (1 mM) for 4 hrs at 37 degrees C, after which time cell viability was determined by measuring the mitochondrial-dependent reduction of 3-(4,5-di-methyliazol-2-yl)-2,5-diphenyltetrazolium bromide to blue formazan. Next, an aqueous solution was incubated with ODQ (as described previously), and superoxide anions were produced by using a hypoxanthine/xanthine-oxidase assay. The chemiluminescence assay was used to evaluate any potential antioxidative effects of ODQ. MEASUREMENTS AND MAIN RESULTS: In vivo, administration of lipoteichoic acid/peptidoglycan or lipopolysaccharide resulted within 6 hrs in hypotension, acute renal dysfunction, hepatocellular injury, and lung injury. Pretreatment of rats with ODQ attenuated the renal dysfunction, lung injury, and hepatocellular injury caused by lipoteichoic acid/peptidoglycan or lipopolysaccharide. In vitro, administration of H2O2 (for 4 hrs) to rat cardiomyoblasts decreased mitochondrial respiration attributable to generation of hydroxyl radicals. Pretreatment of cells with ODQ did not abolish this cell injury. In addition, ODQ did not scavenge superoxide anions. CONCLUSIONS: These results imply that ODQ, an inhibitor of guanylate cyclase, reduces the multiple organ injury and dysfunction caused by wall fragments of Gram-positive or Gram-negative bacteria in the anesthetized rat. The observed protective effects of ODQ are not attributable to the ability of ODQ to reduce the formation or the effects of superoxide anions or hydroxyl radicals.

Animals↗
PubMed2001

A cell wall component from pathogenic and non-pathogenic gram-positive bacteria (peptidoglycan) synergises with endotoxin to cause the release of tumour necrosis factor-alpha, nitric oxide production, shock, and multiple organ injury/dysfunction in the rat.

The incidence of sepsis and septic shock due to gram-positive organisms has increased dramatically over the last two decades. Interestingly, many patients with sepsis/septic shock have both gram-positive and gram-negative bacteria present in the bloodstream and these polymicrobial or "mixed" infections often have a higher mortality than infection due to a single organism. The reason for this observation is unclear. The aim of this study was to investigate whether cell wall fragments from gram-positive and gram-negative bacteria could synergise to cause the release of cytokines, shock, and organ injury/ dysfunction in vivo. Male Wistar rats were anaesthetised and received an intravenous bolus of vehicle (saline), lipopolysaccharide (LPS) from Escherichia coli (0.1 mg/kg), peptidoglycan (Pep G) from Staphylococcus aureus (S10 mg/kg), co-administration of LPS (0.1 mg/kg) and PepG from S. aureus (10 mg/kg), LPS (10 mg/kg), PepG from Bacillus subtilis, or co-administration of LPS and PepG from B. subtilis. Blood pressure and heart rate were monitored for 6 h before plasma samples were taken for the measurement of TNF-alpha, total nitrite, and biochemical indices of organ injury. Peptidoglycan from both pathogenic (S. aureus) and non-pathogenic (B. subtilis) gram-positive bacteria synergised with endotoxin to cause formation of TNF-alpha, nitrite, shock, and organ injury. Synergism between PepG and LPS may partly explain the high mortality associated with mixed bacterial infections, as well as the deleterious effects of translocation of bacteria, or their cell wall components from the gut lumen in patients with sepsis.

Animals↗
PubMed2001

Peptidoglycan primes for LPS-induced release of proinflammatory cytokines in whole human blood.

The pathophysiological mechanisms involved in mixed bacterial infections caused by gram-positive and gram-negative bacteria are largely unknown. The present study examines the potential interaction between lipopolysaccharide (LPS) and peptidoglycan (PepG) in the induction of the sepsis-associated cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-10 in whole human blood. Plasma values of these cytokines were measured by enzyme immunoassays and a TNF bioassay. Co-administration of PepG (10 microg/mL) or muramyl dipeptide (MDP, 1 microg/mL) with LPS (10 ng/mL) caused significantly elevated values of TNF-alpha and IL-6 in the blood that could not be obtained by the sum of the values obtained by each stimulant alone, or by 3-fold higher doses of either bacterial component alone. This phenomenon was observed 1 h after stimulation, throughout the experimental period (24 h), and with different doses of LPS and PepG. In contrast, the release of IL-10 was not influenced by the co-administration of PepG or MDP with LPS. The TNF-alpha release induced by co-administration of LPS and PepG was abrogated after pretreatment with a monoclonal antibody against CD14 (18D11). Addition of PepG or MDP to whole blood caused a 2-fold increase in the surface expression of CD14 on monocytes, as measured by flow cytometry. In contrast, LPS caused decreased expression of this receptor. Our data suggest that PepG and MDP primes human whole blood leukocytes for LPS-induced release of proinflammatory cytokines. We speculate that synergy between PepG and LPS may contribute to the pathogenesis in sepsis caused by mixed bacterial infections.

Cytokines↗
PubMed2001

Peptidoglycan and lipoteichoic acid modify monocyte phenotype in human whole blood.

We examined the influence of the gram-positive cell wall products peptidoglycan (PepG) and lipoteichoic acid (LTA), compared to lipopolysaccharide (LPS), on the monocyte expression of receptors involved in antigen presentation (HLA-DR, B7.1, and B7.2), cell adhesion (intercellular adhesion molecule-1 [ICAM-1] and lymphocyte function associated antigen-3 [LFA-3]), phagocytosis (Fc gamma RI), and cell activation (CD14). We also evaluated possible influences of the immunosuppressive drugs cyclosporine A, tacrolimus, and sirolimus on the expression of these receptors. Pretreatment of whole blood for 4 h with the immunosuppressive drugs did not influence the expression of the surface receptors in normal or stimulated blood. Stimulation with both PepG and LTA caused significant up-regulation of the surface expression of ICAM-1 and HLA-DR on whole blood monocytes, similar to that obtained with LPS, whereas B7.1, B7.2, LFA-3, and Fc gamma RI were not modulated. PepG and LTA also caused increased expression of CD14, whereas LPS down-regulated this molecule. In contrast, we did not detect any significant influence of any of the bacterial products on the plasma concentration of soluble CD14. We hypothesized that the increased expression of surface CD14 in blood stimulated with PepG would prime for cellular activation by LPS. Indeed, we show that PepG and the partial PepG structure muramyl dipeptide acted in synergy with LPS to cause the release of tumor necrosis factor-alpha. The results suggest that PepG and LPS provoke partly different responses on monocyte phenotype and that CD14 may play different roles in the innate response to gram-positive and gram-negative bacteria.

Antigen Presentation↗
PubMed2001

Calpain inhibitor I reduces colon injury caused by dinitrobenzene sulphonic acid in the rat.

BACKGROUND AND AIMS: Inflammatory bowel disease is characterised by oxidative and nitrosative stress, leucocyte infiltration, upregulation of expression of intercellular adhesion molecule 1 (ICAM-1), and upregulation of P-selectin in the colon. The aim of the present study was to examine the effects of calpain inhibitor I in rats subjected to experimental colitis. METHODS: Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). RESULTS: Rats experienced haemorrhagic diarrhoea and weight loss. Four days after administration of DNAB, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as by an increase in myeloperoxidase activity in the mucosa) was associated with upregulation of ICAM-1 and P-selectin as well as high tissue levels of malondialdehyde. Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) polymerase (PARP) showed intense staining in the inflamed colon. Staining of sections of colon obtained from DNBS treated rats with an anti-cyclooxygenase 2 antibody showed diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in macrophages located within the inflamed colon of DNBS treated rats. Calpain inhibitor I (5 mg/kg daily intraperitoneally) significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. Calpain inhibitor I also caused a substantial reduction in (i) degree of colon injury, (ii) rise in myeloperoxidase activity (mucosa), (iii) increase in tissue levels of malondialdehyde, (iv) increase in staining (immunohistochemistry) for nitrotyrosine and PARP, as well as (v) upregulation of ICAM-1 and P-selectin caused by DNBS in the colon. CONCLUSION: Calpain inhibitor I reduces the degree of colitis caused by DNBS. We propose that calpain inhibitor I may be useful in the treatment of inflammatory bowel disease.

Adenosine Diphosphate Ribose↗
PubMed2000

Tempol, a membrane-permeable radical scavenger, reduces dinitrobenzene sulfonic acid-induced colitis.

Inflammatory bowel disease is characterized by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of tempol, a membrane-permeable radical scavenger, in rats subjected to experimental colitis. Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulfonic acid. Rats experienced bloody diarrhea and significant loss of body weight. At 4 days after the administration of dinitrobenzene sulfonic acid, the colon injury comprised of large areas of mucosal necrosis. Neutrophil infiltration (measured as increase in myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1 and expression of P-selectin and high levels of malondialdehyde (an indicator of lipid peroxidation). Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) synthetase showed an intense staining in the inflamed colon. Treatment of rats with tempol (15 mg/kg daily i.p.) significantly reduced the appearance of diarrhea and the loss in body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture as well as a significant reduction in the degree of both neutrophil infiltration and lipid peroxidation in the inflamed colon. Tempol also reduced the appearance of nitrotyrosine and poly (ADP-ribose) synthetase immunoreactivity in the colon as well as the up-regulation of ICAM-1 and P-selectin. The results of this study suggest that membrane-permeable radical scavengers, such as tempol, exert beneficial effects in experimental colitis and may, hence, be useful in the treatment of inflammatory bowel disease.

Animals↗
PubMed2000

Effects of tempol, a membrane-permeable radical scavenger, in a gerbil model of brain injury.

There is evidence that the excessive generation of reactive-oxygen radicals contributes to the brain injury associated with transient, cerebral ischemia. This study investigates the effects of tempol, a small, water-soluble molecule, that crosses biological membranes, on the brain injury caused by bilateral occlusion and reperfusion of both common carotid arteries in the gerbil (BCO). Treatment of gerbils with tempol (30 mg/kg i.p. at 30 min prior to reperfusion and at 1 and 6 h after the onset of reperfusion) reduced the formation of post-ischemic brain oedema. Tempol also attenuated the increase in the cerebral levels of malondialdehyde (MDA) and the hippocampal levels of myeloperoxidase (MPO) caused by cerebral ischemia and reperfusion. The immunohistochemical analysis of the hippocampal region of brains subjected to ischemia-reperfusion exhibited positive staining for nitrotyrosine (an indicator of the generation of peroxynitrite) and poly(ADP-ribose) synthetase (PARS) (an indicator of the activation of this nuclear enzyme secondary to single strand breaks in DNA). In gerbils subjected to BCO, which were treated with tempol, the degree of staining for nitrotyrosine and PARS was markedly reduced. Tempol increased survival and reduced the hyperactivity (secondary to the ischemia-induced neurodegeneration) caused by cerebral ischemia and reperfusion. The loss of neurons from the pyramidal layer of the CA1 region caused by ischemia and reperfusion was also attenuated by treatment of gerbils with tempol. This is the first evidence that the membrane-permeable, radical scavenger tempol reduces the cerebral injury caused by transient, cerebral ischemia in vivo.

Animals↗
PubMed2000

Effects of tempol, a membrane-permeable radical scavenger, in a rodent model of carrageenan-induced pleurisy.

Carrageenan causes enhanced formation of reactive oxygen species, which contribute to the pathophysiology of inflammation. We have investigated the effects of tempol, a membrane-permeable radical scavenger, in rats subjected to carrageenan-induced pleurisy. Treatment of rats with tempol (10, 30, or 100 mg/kg 15 min prior to carrageenan) attenuated the pleural exudation and the migration of polymorphonuclear cells caused by carrageenan dose dependently. Tempol also attenuated the lung injury (histology) as well as the increase in the tissue levels of myeloperoxidase and malondialdehyde caused by carrageenan in the lung. However, tempol did not inhibit the activity of inducible nitric oxide synthase in the lungs. Immunohistochemical analysis for nitrotyrosine revealed positive staining in lungs from carrageenan-treated rats. Lung tissue sections from carrageenan-treated rats also showed positive staining for poly-(ADP-ribose) synthetase (PARS). The degree of staining for nitrotyrosine and PARS was markedly reduced in tissue sections obtained from carrageenan-treated rats, which had received tempol (100 mg/kg). Furthermore, treatment of rats with tempol significantly reduced (i) the formation of peroxynitrite, (ii) the DNA damage, (iii) the impairment in mitochondrial respiration, and (iv) the fall in the cellular level of NAD(+) observed in macrophages harvested from the pleural cavity of rats treated with carrageenan. Tempol also attenuated the cell injury caused by hydrogen peroxide (1 mM) in cultured human endothelial cells. This study provides the first evidence that tempol, a small molecule which permeates biological membranes and scavenges ROS, attenuates the degree of inflammation and tissue damage associated with carageenan-induced pleurisy in the rat. The mechanisms of the anti-inflammatory effect of tempol are discussed.

Animals↗
PubMed2000

Beneficial effects of tempol, a membrane-permeable radical scavenger, in a rodent model of collagen-induced arthritis.

OBJECTIVE: To investigate the effects of tempol, a membrane-permeable radical scavenger, in rats with collagen-induced arthritis (CIA). METHODS: CIA was induced in Lewis rats by intradermal injection of 100 microl of an emulsion of 100 microg of bovine type II collagen (CII) in complete Freund's adjuvant (FCA) at the base of the tail. On day 21, a second injection of CII in FCA was administered. RESULTS: Lewis rats developed an erosive arthritis of the hind paws when immunized with CII in FCA. Macroscopic evidence of CIA first appeared as periarticular erythema and edema in the hind paws. The incidence of CIA was 100% by day 27 in the CII-challenged rats, and the severity of CIA progressed over a 35-day period. Radiographs revealed focal resorption of bone, with osteophyte formation in the tibiotarsal joint, and soft tissue swelling. The histopathologic features included erosion of the cartilage at the joint margins. Treatment of rats with tempol (10 mg/kg/day intraperitoneally) starting at the onset of arthritis (day 23) delayed the development of the clinical signs on days 24-35 and improved the histologic status of the knee and paw. Immunohistochemical analysis for nitrotyrosine and poly(ADP-ribose) synthetase (PARS) revealed positive staining in the inflamed joints of CII-treated rats. The degree of nitrotyrosine and PARS staining was markedly reduced in tissue sections obtained from CII-treated rats that had received tempol. Furthermore, radiographs revealed protection against bone resorption and osteophyte formation in the joints of tempol-treated rats. CONCLUSION: This study is the first to provide evidence that tempol, a small molecule that permeates biologic membranes and scavenges reactive oxygen species, attenuates the degree of chronic inflammation and tissue damage associated with CIA in the rat.

Animals↗
PubMed2000

The tyrosine kinase inhibitor tyrphostin AG126 reduces the development of acute and chronic inflammation.

Protein tyrosine kinases help to regulate the expression of many genes that play important roles in inflammation. Here we investigate the effects of the tyrosine kinase inhibitor tyrphostin AG126 in two animal models of acute and chronic inflammation, carrageenan-induced pleurisy and collagen-induced arthritis. We report here that tyrphostin AG126 (given at 1, 3, or 10 mg/kg i.p. in the pleurisy model or 5 mg/kg i.p. every 48 hours in the arthritis model) exerts potent anti-inflammatory effects in animal models of acute and chronic inflammation in vivo. These include the inhibition of pleural exudate formation and mononuclear cell infiltration (pleurisy model) and the development of clinical signs and tissue injury (arthritis model). Furthermore, tyrphostin AG126 reduced the staining for nitrotyrosine and poly (ADP-ribose) polymerase (by immunohistochemistry) and the expression of inducible nitric oxide synthase and cyclooxygenase-2 in the lungs of carrageenan-treated rats and in the joints from collagen-treated rats. Thus, we provide the first evidence that prevention of the activation of protein tyrosine kinases reduces the development of acute and chronic inflammation, and that inhibition of the activity of certain tyrosine kinases may represent a novel approach for the therapy of inflammation.

Acute Disease↗
PubMed2000

Calpain inhibitor I reduces the development of acute and chronic inflammation.

There is limited evidence that inhibition of the activity of the protease calpain I reduces inflammation. Here we investigate the effects of calpain inhibitor I in animal models of acute and chronic inflammation (carrageenan-induced pleurisy and collagen-induced arthritis). We report here for the first time that calpain inhibitor I (given at 5, 10, or 20 mg/kg i.p. in the pleurisy model or at 5 mg/kg i.p every 48 hours in the arthritis model) exerts potent anti-inflammatory effects (eg, inhibition of pleural exudate formation, mononuclear cell infiltration, delayed the development of the clinical signs and histological injury) in vivo. Furthermore, calpain inhibitor I reduced (1) the staining for nitrotyrosine and poly (ADP-ribose) polymerase (immunohistochemistry) and (2) the expression of inducible nitric oxide synthase and cyclooxygenase-2 in the lungs of carrageenan-treated rats and in joints from collagen-treated rats. Thus, prevention of the activation of calpain I reduces the development of acute and chronic inflammation. Inhibition of calpain I activity may represent a novel therapeutic approach for the therapy of inflammation.

Acute Disease↗
PubMed2000

Selective activation of E-type prostanoid(3)-receptors reduces myocardial infarct size. A novel insight into the cardioprotective effects of prostaglandins.

Prostaglandins (PGs) and other eicosanoids are members of a large family of lipid mediators (autacoids). In 1978, Lefer and colleagues (Science 200, 52-55 [1978]) reported that prostacyclin reduces the myocardial tissue injury caused by coronary artery occlusion and reperfusion in the cat. Since this discovery, more than 50 papers have reported on the cardioprotective effects of vasodilator PGs, including prostacyclin. The cardioprotective effects of PGs are due in part to (1) a reduction in afterload, (2) an increase in coronary blood flow, (3) the inhibition of platelet function, and (4) the inhibition of the activation and extravasation of polymorphonuclear granulocytes. All of these effects are secondary to the activation of EP (E-type prostanoid)(2)-receptors, which activate G(s)-protein and, hence, adenylate cyclase. In addition, the protection of organs such as the heart by PGs has been attributed to a cytoprotective effect of these agents, the mechanism of which is largely unknown. We recently have discovered that certain E-type PGs, which do not activate EP(2)-receptors, also reduce myocardial infarct size, without causing a fall in blood pressure (EP(2)-receptor-mediated effects). Having provided a brief introduction into the role of eicosanoids in ischaemia-reperfusion injury of the heart, this review focuses on the recent discovery that selective agonists of EP(3)-receptors reduce myocardial infarct size, without causing haemodynamic side effects. The mechanisms of the cardioprotective effects of these agents are discussed, as are the therapeutic implications.

Animals↗
PubMed2000

The tyrosine kinase inhibitor tyrphostin AG 126 reduced the development of colitis in the rat.

Inflammatory bowel disease is characterized by oxidative and nitrosative stress, leukocyte infiltration, up-regulation of the expression of intercellular adhesion molecule-1 (ICAM-1), and up-regulation of P-selectin in the colon. Here we investigate the effects of the tyrosine kinase inhibitor, Tyrphostin AG 126, in rats subjected to experimental colitis. Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). Rats experienced hemorrhagic diarrhea and weight loss. Four days after administration of DNBS, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as an increase in myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1 and P-selectin, as well as high tissue levels of malondialdehyde. Immunohistochemistry for nitrotyrosine and poly(ADP-ribose) polymerase showed an intense staining in the inflamed colon. Staining with an anti-COX-2 antibody of sections of colon obtained from DNBS-treated rats showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in macrophages located within the inflamed colon of DNBS-treated rats. Tyrphostin AG 126 (5 mg/kg daily ip) significantly reduced the degree of hemorrhagic diarrhea and weight loss caused by administration of DNBS. Tyrphostin AG 126 also caused a substantial reduction of (1) the phosphorylation of tyrosine residues of proteins (immunoblots of inflamed colon), (2) the degree of colonic injury, (3) the rise in myeloperoxidase activity (mucosa), (4) the increase in the tissue levels of malondialdehyde, (5) the increase in staining (immunohistochemistry) for nitrotyrosine and poly(ADP-ribose) polymerase, as well as (6) the up-regulation of ICAM-1 and P-selectin caused by DNBS in the colon. Thus, we provide the first evidence that the tyrosine kinase inhibitor Tyrphostin AG126 reduces the degree of colitis caused by DNBS.

Animals↗
PubMed2000

Effects of 5-aminoisoquinolinone, a water-soluble, potent inhibitor of the activity of poly (ADP-ribose) polymerase on the organ injury and dysfunction caused by haemorrhagic shock.

Poly (ADP-ribose) synthetase (PARP) is a nuclear enzyme activated by strand breaks in DNA, which are caused inter alia by reactive oxygen species (ROS). Here we report on (i) a new synthesis of a water-soluble and potent PARP inhibitor, 5-aminoisoquinolinone (5-AIQ) and (ii) investigate the effects of 5-AIQ on the circulatory failure and the organ injury/dysfunction caused by haemorrhage and resuscitation in the anaesthetized rat. Exposure of human cardiac myoblasts (Girardi cells) to hydrogen peroxide (H(2)O(2), 3 mM for 1 h, n=9) caused a substantial increase in PARP activity. Pre-treatment of these cells with 5-AIQ (1 microM - 1 mM, 10 min prior to H(2)O(2)) caused a concentration-dependent inhibition of PARP activity (IC(50): approximately 0.01 mM, n=6). Haemorrhage and resuscitation resulted (within 4 h after resuscitation) in a delayed fall in blood pressure (circulatory failure) as well as in rises in the serum levels of (i) urea and creatinine (renal dysfunction), (ii) aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl-transferase (gamma-GT) (liver injury and dysfunction), (iii) lipase (pancreatic injury) and (iv) creatine kinase (CK) (neuromuscular injury) (n=10). Administration (5 min prior to resuscitation of 5-AIQ) (0.03 mg kg(-1) i.v., n=8, or 0.3 mg kg(-1) i.v., n=10) reduced (in a dose-related fashion) the multiple organ injury and dysfunction, but did not affect the circulatory failure, associated with haemorrhagic shock. Thus, 5-AIQ abolishes the multiple organ injury caused by severe haemorrhage and resuscitation.

Alanine Transaminase↗
PubMed2000

Tempol, a membrane-permeable radical scavenger, reduces oxidant stress-mediated renal dysfunction and injury in the rat.

BACKGROUND: The generation of reactive oxygen species (ROS) contributes to the pathogenesis of renal ischemia-reperfusion injury. The aim of this study was to investigate the effects of tempol in (1) an in vivo rat model of renal ischemia/reperfusion injury and on (2) cellular injury and death of rat renal proximal tubular (PT) cells exposed to oxidant stress in the form of hydrogen peroxide (H2O2). METHODS: Male Wistar rats underwent bilateral renal pedicle clamping for 45 minutes followed by reperfusion for six hours. Tempol (30 mg/kg/h), desferrioxamine (DEF; 40 mg/kg/h), or a combination of tempol (30 mg/kg/h) and DEF (40 mg/kg/h) were administered prior to and throughout reperfusion. Plasma concentrations of urea, creatinine, Na+, gamma-glutamyl transferase (gammaGT), aspartate aminotransferase (AST), and urinary Na+ and N-acetyl-beta-D-glucosaminidase (NAG) were measured for the assessment of renal function and reperfusion injury. Kidney myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were measured for assessment of polymorphonuclear (PMN) cell infiltration and lipid peroxidation, respectively. Renal sections were used for histologic grading of renal injury and for immunohistochemical localization of nitrotyrosine and poly(ADP-ribose) synthetase (PARS). Primary cultures of rat PT cells were incubated with H2O2 (1 mmol/L for 4 h) either in the absence or presence of increasing concentrations of tempol (0.03 to 10 mmol/L), DEF (0.03 to 10 mmol/L), or a combination of tempol (3 mmol/L) or DEF (3 mmol/L). PT cell injury and death were determined by evaluating mitochondrial respiration and lactate dehydrogenase (LDH) release, respectively. RESULTS: In vivo, tempol significantly reduced the increase in urea, creatinine, gammaGT, AST, NAG, and FENa produced by renal ischemia/reperfusion, suggesting an improvement in both renal function and injury. Tempol also significantly reduced kidney MPO activity and MDA levels, indicating a reduction in PMN infiltration and lipid peroxidation, respectively. Tempol reduced the histologic evidence of renal damage associated with ischemia/reperfusion and caused a substantial reduction in the staining for nitrotyrosine and PARS, suggesting reduced nitrosative and oxidative stress. In vitro, tempol significantly attenuated H2O2-mediated decrease in mitochondrial respiration and increase in LDH release from rat PT cells, indicating a reduction in cell injury and death. Both in vivo and in vitro, the beneficial actions of tempol were similar to those obtained using the Fe2+ chelator DEF. However, coadministration of DEF and tempol did not produce any additional beneficial actions against renal ischemia/reperfusion injury or against oxidative stress-mediated PT cell injury/death. CONCLUSION: Our results suggest that the membrane-permeable radical scavenger, tempol, reduces the renal dysfunction and injury associated with ischemia/reperfusion of the kidney.

Acute Kidney Injury↗