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J E Repine

Publications and source records attributed to J E Repine.

At least 145 records · Page 8Linked to original sources
PubMed1988

Cardiac oxidase systems mediate oxygen metabolite reperfusion injury.

To investigate the mechanism of cardiac ischemia reperfusion injury, we fed rats tungsten (3 weeks) to inhibit molybdenum-dependent oxidase enzymes. Tungsten-treated isolated perfusion hearts (Langendorff, ventricular balloon, 37 degrees C) had negligible xanthine oxidase activity (less than 0.3 vs greater than 8.0 U/gm myocardium) and improved recovery of developed pressure (DP), contractility (+dP/dt), and compliance (-dP/dt) after 20 minutes of global ischemia (37 degrees C) and 40 minutes of reperfusion. Furthermore, the addition of dimethylthiourea, a freely diffusible O2 metabolite scavenger, but not equimolar urea, a non-O2 metabolite scavenger, improved recovery. High-dose urea improved recovery more than control but less than dimethylthiourea. Combining tungsten and equimolar urea improved recovery the same as dimethylthiourea. We conclude that: (1) inhibition of myocardial oxidase enzymes (including xanthine oxidase) improves recovery of ventricular function after ischemia and reperfusion in the isolated rat heart, (2) infusion (during reperfusion) of a permeable O2 metabolite scavenger (dimethylthiourea) but not equimolar urea improves recovery of ventricular function, (3) infusion of higher concentrations of urea improves postischemic function, and (4) myocardial reperfusion injury is distinguishable from ischemic injury.

Animals↗
PubMed1987

Cerebral ischemia-reperfusion injury in the gerbil.

Gerbils subjected to cerebral ischemia (unilateral carotid occlusion for 6 hr) were either asymptomatic or developed increasingly severe neurologic deficits which correlated with degrees of brain swelling (weights of ischemic hemisphere versus the contralateral control hemispheres) following 3 hr of reperfusion. Asymptomatic gerbils or gerbils suffering only mild deficits survived for 1 week following reperfusion while gerbils suffering moderate to severe deficits had a poor survival rate with only 22% remaining alive after 1 week.

Animals↗
PubMed1987

O2 metabolites cause reperfusion injury after short but not prolonged renal ischemia.

Toxic O2 metabolites have been postulated to contribute to renal ischemia-reperfusion injury, but their biochemical assessment and contribution as a function of the duration of ischemia is unclear. To address this issue we measured renal function and renal cortical glutathione levels following 20, 30, or 45 min of ischemia in situ and then 60 min of reperfusion by the isolated kidney technique. Increasing durations of ischemia were associated with progressive decreases in perfusion flow rate, glomerular filtration rate, tubular Na reabsorption, and renal cortical glutathione following reperfusion. However, reperfusion following simultaneous addition of the permeable O2 metabolite scavenger dimethylthiourea (DMTU; but not urea) prevented glutathione consumption and attenuated reperfusion-induced injury after 20 and 30 min of ischemia. In contrast, reperfusion with DMTU prevented glutathione consumption but did not improve renal function after 45 min of ischemia. Similarly, reperfusion with dimethyl sulfoxide also attenuated renal injury after 20 and 30 min, but not after 45 min of ischemia. Thus reperfusion of kidneys made ischemic for 20 or 30 min is associated with decreases in tissue glutathione and renal function that were both inhibitable by addition of O2 metabolite scavengers during reperfusion. In contrast, addition of O2 metabolite scavengers during reperfusion of kidneys previously made ischemic for 45 min prevented decreases in glutathione but did not improve renal function. We conclude that O2 metabolites formed during reperfusion contribute to functional impairment in kidneys made ischemic for short durations up to 30 min) but that after prolonged ischemia (greater than 30 min) injury is primarily mediated by non-O2 metabolite-dependent cellular events.

Animals↗
PubMed1987

O2 metabolite-mediated injury in perfused kidneys is reflected by consumption of DMTU and glutathione.

The contribution of toxic oxygen (O2) metabolites to ischemic renal injury is unclear because they have not been added directly to the kidney and few ways exist to effectively measure and assess the effect of these highly reactive products in biological systems. Our goal was to determine the effect of hydrogen peroxide (H2O2) or H2O2-derived products on renal function and to determine whether H2O2-mediated renal injury was reflected by consumption of dimethylthiourea (DMTU) (an exogenous O2 metabolic scavenger), depletion of renal cortical total glutathione (an endogenous O2 metabolite scavenger), and/or adenosine triphosphate (ATP). We found that addition of glucose oxidase (GO) or H2O2 to isolated perfused rat kidneys caused injury that was manifested by decreases in glomerular filtration rate, perfusion flow rate, and sodium reabsorption and that was prevented by addition of catalase (CAT) (but not inactivated CAT) or large doses of DMTU (15 mM), but not urea (15 mM). To further ascertain if the protective effect of DMTU was due to reacting with a scavenging H2O2, we conducted parallel experiments in which we measured the consumption of smaller doses of DMTU (1 mM) in kidneys perfused with GO or H2O2. We found that addition of increasing concentrations of H2O2 decreased DMTU concentration. Renal cortical total glutathione and ATP levels were also decreased by addition of GO or H2O2. In contrast to perfusion with GO or H2O2, perfusion with elastase or collagenase also caused renal injury and decreases in ATP but did not decrease DMTU concentration or tissue total glutathione. We conclude that H2O2 or H2O2-derived products are acutely toxic to the kidney and that decreases in perfusate DMTU concentration and tissue total glutathione, but not tissue ATP, may be useful for specifically assessing the presence and/or toxicity of H2O2 in renal and other biological systems.

Adenosine Triphosphate↗
PubMed1987

Antioxidants protect cultured bovine lung endothelial cells from injury by endotoxin.

Endotoxin injures bovine pulmonary endothelial cells in culture but the cytotoxicity is unaffected by a host of antiinflammatory drugs. We hypothesized that agents which could decrease intracellular concentrations of toxic metabolites of O2 would prevent endotoxin effects on cultured pulmonary artery endothelial cells. We measured endotoxin-induced release of lactate dehydrogenase (LDH) from and production of prostanoids by cultured bovine pulmonary endothelial cells in the presence and absence of dimethyl sulfoxide (DMSO) and the xanthine oxidase inhibitor allopurinol. Escherichia coli endotoxin (0.001-10 micrograms/ml) caused a dose-related release of LDH and stimulated production of both prostacyclin [measured as 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha)] and prostaglandin E2 (PGE2). Both DMSO and allopurinol decreased endotoxin-induced LDH release; this effect was related to concentration of the drugs (0-2% for DMSO and 0-0.3 mg/ml for allopurinol). Both drugs also prevented endotoxin-induced changes in endothelial morphology. Endotoxin increased intracellular reduction of the redox dye nitro blue tetrazolium, caused intracellular oxidation of 2',7'-dichlorofluorescein diacetate and caused release of conjugated dienes from endothelial cells; both DMSO and allopurinol inhibited those responses. DMSO, but not allopurinol, prevented endotoxin-induced production of prostacyclin and PGE2 by endothelium. Direct injury of pulmonary endothelium by endotoxin is inhibited by two chemically dissimilar drugs which have a common potential for decreasing intracellular concentrations of toxic metabolites of O2; indirect evidence suggests that potential as a mechanism for the protective effects of the drugs.

Allopurinol↗
PubMed1987

Antiarrhythmic agents diminish thiourea-induced pulmonary vascular protein leak in rats.

Drugs possessing membrane stabilizing activity might act to diminish the augmented microvascular permeability resulting from acute lung injury. To test this rats were pretreated with quinidine, procainamide, or lidocaine and then given the lung injury-inducing agent thiourea. Vascular permeability, assessed as the extravascular accumulation of radiolabeled protein, was increased more than threefold by thiourea. This increase was diminished by 29, 34, and 43% after pretreatment with procainamide, quinidine, and lidocaine, respectively. Lidocaine also returned the thiourea-induced increase in lung wet weight-to-dry weight ratios to control levels. This protection was not likely due to hemodynamic effects of these agents, since no differences were noted in cardiac output between pretreated rats and those receiving thiourea alone and a small increase in mean pulmonary arterial pressure in the lidocaine-pretreatment group was the only difference noted. O2 metabolites have been implicated in the pathogenesis of thiourea-induced lung injury. None of these agents scavenged O2- or H2O2 directly, but quinidine and procainamide diminished in vitro neutrophil O2- and H2O2 production, and lidocaine inhibited neutrophil H2O2 production. However, neutropenia (PMN less than 100/ml) induced with either vinblastine or cyclophosphamide (Cytoxan) failed to prevent thiourea-induced increases in pulmonary vascular protein leak. In conclusion, procainamide, quinidine, and lidocaine diminished lung injury in rats after thiourea. Although these agents diminish PMN O2 metabolite production in vitro their salutary role in thiourea-induced lung injury appears to be through an unknown mechanism that is independent of their effects on neutrophil O2 metabolite-dependent toxicity.

Animals↗
PubMed1987

Xanthine oxidase mediates elastase-induced injury to isolated lungs and endothelium.

Xanthine oxidase (XO)-generated toxic O2 metabolites appear to contribute to reperfusion injury, but the possibility that XO is involved in hyperoxic or neutrophil elastase-mediated injury has not been investigated. We found that lungs isolated from rats fed a tungsten-rich diet had negligible XO activities and after exposure to hyperoxia developed less acute edematous injury during perfusion with buffer or purified neutrophil elastase than XO-replete lungs from control rats which had been exposed to hyperoxia. In parallel, tungsten-treated XO-depleted cultured bovine pulmonary arterial endothelial cells made less superoxide anion and as monolayers leaked less 125I-labeled albumin after exposure to neutrophil elastase than XO-replete endothelial cell monolayers. Our findings suggest that XO-derived O2 metabolites contribute to acute edematous lung injury from hyperoxia directly and by enhancing susceptibility to neutrophil elastase.

Animals↗
PubMed1987

Attenuation of dysfunction in the postischemic 'stunned' myocardium by dimethylthiourea.

The mechanism for the prolonged contractile dysfunction observed in myocardium reperfused after reversible regional ischemia ("stunned" myocardium) is unclear. Recent studies suggest that myocardial stunning may be mediated by oxygen-derived free radicals, but the precise molecular species involved remain unknown. Thus we explored the role of the highly cytotoxic hydroxyl radical in regional postischemic dysfunction by using dimethylthiourea (DMTU), an effective and highly permeable hydroxyl radical scavenger. Open-chest dogs undergoing a 15 min occlusion of the left anterior descending coronary artery followed by 4 hr of reperfusion received either DMTU (0.5 g/kg iv over 45 min starting 30 min before occlusion, n = 14) or saline (n = 15). Control and treated dogs were comparable with respect to variables that may affect postischemic dysfunction, including heart rate, aortic pressure, left atrial pressure, arterial blood gases and hemoglobin concentration, size of the occluded bed (determined by postmortem perfusion), and collateral blood flow (determined by radioactive microspheres). Regional myocardial function was assessed by measuring wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under baseline conditions and similar degrees of dyskinesis during ischemia. After reperfusion, however, wall thickening (expressed as percent of baseline) was considerably greater in treated as compared with control dogs: 53 +/- 9% (mean +/- SEM) vs 9 +/- 14% (p less than .03) at 1 hr, 55 +/- 9% vs 23 +/- 13% (p less than .05) at 2 hr, 60 +/- 9% vs 28 +/- 14% (p less than .05) at 3 hr, and 67 +/- 5% vs 36 +/- 13% (p less than .05) at 4 hr. Thus DMTU produced a significant and sustained improvement in recovery of contractile function. In concentrations greater than the plasma levels attained in vivo, DMTU did not scavenge either hydrogen peroxide or superoxide anion in vitro. These results suggest that the myocardial dysfunction occurring after a brief episode of regional ischemia is mediated in part by the hydroxyl radical.

Animals↗
PubMed1987

Neutrophil-derived oxygen metabolites stimulate thromboxane release, pulmonary artery pressure increases, and weight gains in isolated perfused rat lungs.

Addition of normal human neutrophils and the neutrophil stimulant, phorbol myristate acetate (PMA), caused perfusate thromboxane (TXB2) elevations, pulmonary artery pressure (PAP) increases, and lung weight gains in isolated perfused rat lungs. Addition of PMA and neutrophils that do not generate O2 metabolites from a patient with chronic granulomatous disease (CGD) - or addition of PMA and normal neutrophils with the purported O2 metabolite scavenger, dimethylthiourea (DMTU) - also caused PAP increases but did not cause perfusate TXB2 elevations or lung weight gains in isolated lungs. In parallel, mixtures of normal neutrophils and PMA made hydrogen peroxide (H2O2) concentrations in vitro which exceeded concentrations found in mixtures containing PMA and CGD neutrophils or mixtures containing PMA, normal neutrophils, and DMTU. TXB2 levels were not detectable in mixtures containing normal neutrophils and PMA in vitro. Our results indicate that neutrophil-derived O2 metabolites contribute to perfusate TXB2 elevations and lung weight gains but not PAP increases in isolated perfused rat lungs.

Animals↗
PubMed1987

Recombinant tumor necrosis factor/cachectin and interleukin 1 pretreatment decreases lung oxidized glutathione accumulation, lung injury, and mortality in rats exposed to hyperoxia.

Single, preexposure, parenteral injection with both recombinant tumor necrosis factor/cachectin (TNF/C) and interleukin-1 (IL-1) prolonged the survival of rats (144 +/- 9 h) in continuous hyperoxia (greater than 99% O2 at 1 atm) when compared with rats injected with boiled TNF/C and boiled IL-1 (61 +/- 2 h), TNF/C alone (61 +/- 2 h), IL-1 alone (62 +/- 2 h), or saline (64 +/- 3 h). After exposure to hyperoxia for 52 h, pleural effusion volume, pulmonary artery pressure, total pulmonary resistance, and lung morphologic damage were decreased in those rats given TNF/C and IL-1 as compared with saline-injected rats. In parallel, ratios of reduced (GSH) to oxidized (GSSG) glutathione were greater (P less than 0.05) in lungs of TNF/C + IL-1-injected rats (91 +/- 20) than of saline-injected rats (30 +/- 4) that had been exposed to hyperoxia for 52 h. No differences were found in superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, or catalase activities in lungs of TNF/C + IL-1- or saline-treated, hyperoxia-exposed rats. Our results indicate that pretreatment with TNF/C and IL-1 favorably altered lung glutathione redox status, decreased lung injury, and enhanced survival of rats exposed to hyperoxia.

Animals↗
PubMed1986

Persistent bactericidal defect in neutrophils from a young woman who recovered from toxic shock syndrome.

We have previously found transient menstruation-associated abnormalities in the in vitro bactericidal function of neutrophils from females who have recovered from toxic shock syndrome (TSS). We now report the case of a young woman who has also recovered from TSS, but who has a persistent, non-menstruation-associated defect in the ability of her neutrophils to kill Staphylococcus aureus in vitro.

Adolescent↗
PubMed1986

Increased incidence of menstruation-associated bactericidal defects in neutrophils from women who have recovered from toxic shock syndrome.

There is a growing suspicion that a host abnormality may contribute to the pathogenesis of toxic shock syndrome (TSS). We found that females (5 of 5) who had recovered from TSS had transient, menstruation-associated decreases (greater than or equal to 9%) in the ability of their neutrophils to kill Staphylococcus aureus. 502A in vitro more often (P = 0.040 by Fisher's exact test) than non-TSS-affected control subjects (5 of 12). In addition, the average decrease in bactericidal activity in neutrophils obtained during menstruation from recovered TSS patients was 30 +/- 9% compared to 7 +/- 7% for neutrophils from non-TSS-affected control subjects. The results are consistent with the possibility that transient menstruation-associated decreases in neutrophil bactericidal function may indicate susceptibility and/or contribute to the development of TSS.

Adult↗
PubMed1986

Dimethylthiourea decreases acute lung edema in phorbol myristate acetate-treated rabbits.

Treatment with dimethylthiourea (DMTU), a potent O2 metabolite scavenger, prevented neutrophil-mediated acute edema in lungs of rabbits given phorbol myristate acetate (PMA) and in isolated rabbit lungs perfused with neutrophils and PMA. DMTU-treated rabbits given PMA did not increase their lung weight-to-total body weight ratios (5.0 +/- 0.3) or lung lavage albumin concentrations (14 +/- 4.6 mg/dl) in comparison to untreated rabbits given PMA (6.6 +/- 0.5 and 60 +/- 10 mg/dl, respectively). Similarly, DMTU-treated isolated rabbit lungs perfused with neutrophils and PMA did not gain weight (0 g) or increase their lavage albumin concentrations (82 +/- 17 mg/dl) in comparison to untreated lungs perfused with neutrophils and PMA (71 +/- 3.1 g and 1,299 +/- 47 mg/dl, respectively). DMTU did not appear to decrease edema by preventing increases in pulmonary arterial pressures (PAP). First, treatment with DMTU did not decrease initial PAP increases in rabbits given PMA. Second, even though addition of DMTU attenuated PAP increases in isolated lungs perfused with neutrophils and PMA, DMTU-treated isolated lungs did not develop acute edema when subjected to mechanical increases in venous outflow pressures. The mechanism by which DMTU decreases lung edema is unclear but may involve scavenging of toxic O2 metabolites, since DMTU also decreased hydrogen peroxide (H2O2) and hydroxyl radical (OH) concentrations in in vitro mixtures containing neutrophils and PMA.

Acute Disease↗
PubMed1986

O2 metabolites and neutrophil elastase synergistically cause edematous injury in isolated rat lungs.

Addition of glucose oxidase (GO) increased H2O2 concentrations and decreased antielastolytic activities of beta-D-glucose containing perfusates of isolated rat lungs. Pretreatment with GO also caused acute edematous injury (increased lung weight gains, increased recovery of Ficoll in lung lavages, and increased pulmonary arterial pressures) in isolated lungs perfused with purified human neutrophil elastase (NE). Acute edematous injury in isolated lungs pretreated with GO and then NE exceeded levels found in lungs following addition of GO or NE alone or NE before GO. Simultaneous addition of catalase (an H2O2 scavenger) or methoxy-succinyl-L-alanyl-L-alanyl-prolyl-L-valine-chloromethyl ketone (an NE inhibitor, but not aminotriazole-inactivated catalase, N-tosyl-L-phenyl-alanine chloromethyl ketone (a chymotrypsin inhibitor) or N-alpha-p-tosyl-L-lysine chloromethyl ketone (a trypsin inhibitor), prevented acute edematous injury in isolated lungs perfused with both GO and NE. This observation indicated that injury was dependent on both H2O2 and NE, especially since the relative inactivating specificities of the inhibitors for H2O2 or NE, respectively, were confirmed under similar conditions in vitro. The synergistic nature of the interaction between H2O2 and NE-mediated injury was further clarified when GO- and NE-induced lung injury was prevented by addition of an oxidant-resistant NE inhibitor (Eglin-C), but not an oxidant-sensitive NE inhibitor (human alpha 1-protease inhibitor, alpha 1PI). Moreover, treatment with H2O2 also decreased the ability of alpha 1PI but not Eglin-C to decrease NE activity in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Natural mycobacteriostatic activity in human monocyte-derived adherent cells.

The effects of human monocyte maturity on the replication of virulent Mycobacterium tuberculosis were examined. Mycobacteria grew readily in freshly isolated, adherent peripheral blood monocytes and in monocyte-derived macrophages obtained after 7 days in culture, as measured by counts of acid-fast bacilli and colony-forming units. Monocytes cultured for only 3 days before infection, however, were less permissive for the mycobacteria than either uncultured or 7-day cells. The association between the low permissiveness of 3-day cells and superoxide production was examined. Mycobacteria induced only a slight increase in superoxide production during the first 60 min of infection in uncultured and in 3-day cells, and no increase in cells cultured for 7 days before infection. Freshly isolated adherent cells produced small amounts of superoxide in response to phorbol myristate acetate (PMA) stimulation, but PMA-induced superoxide production increased steadily for 7 days. Mycobacteria had no effect on superoxide production by PMA-stimulated adherent cells. These results suggest that the suppressive activity of the 3-day cells is not associated with the production of increased amounts of reactive oxygen species.

Cell Survival↗
PubMed1986

Erythrocytes from cigarette smokers contain more glutathione and catalase and protect endothelial cells from hydrogen peroxide better than do erythrocytes from nonsmokers.

Recent observations regarding the ability of intracellular erythrocyte (RBC) antioxidants to decrease O2 metabolite-mediated injury to lung tissues has prompted interest in the RBC antioxidants of patients with lung disease. We found that RBC from 14 healthy, age- and gender-matched cigarette smokers contained more (p less than 0.05) glutathione (6.3 +/- 0.4 microM/g Hgb versus 5.0 +/- 0.3 microM/g Hgb) and catalase (249,533 +/- 8,307 units/g Hgb versus 222,617 +/- 7,180 units/g Hgb) than did RBC from nonsmokers. In contrast, RBC from cigarette smokers and nonsmokers contained the same activities of glutathione peroxidase (21.4 +/- 1.2 units/g Hgb versus 20.4 +/- 5.5 units/g Hgb). RBC from cigarette smokers also protected bovine pulmonary artery endothelial cells in culture from hydrogen peroxide (H2O2) better (p less than 0.005) than did RBC from nonsmokers (52.1 +/- 6.1% protection versus 31.9 +/- 5.7% protection). The results suggest that alterations in RBC antioxidants may reflect exposure and/or affect susceptibility to oxidant-induced injury.

Animals↗