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J E Repine

Publications and source records attributed to J E Repine.

At least 19 recordsLinked to original sources
PubMed1992

Hypoxia injures endothelial cells by increasing endogenous xanthine oxidase activity.

Exposure to decreasing oxygen tensions progressively increased xanthine dehydrogenase (XD) and xanthine oxidase (XO) activities over 48 hr in cultured pulmonary artery endothelial cells (EC) without altering XD/XO ratios. Increases in XD and XO activity in EC induced by hypoxia were associated upon reoxygenation with increased (P less than 0.05) extracellular superoxide anion (O2-.) levels that were inhibited by treatment with XO inhibitors (tungsten, allopurinol) or an anion-channel blocker (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid). EC monolayers subjected to hypoxia/reoxygenation also leaked more preloaded 51Cr, were more adherent to neutrophils, and permitted greater albumin transit than control monolayers. Treatment with tungsten, allopurinol, and/or superoxide dismutase decreased (P less than 0.05) 51Cr release, neutrophil adherence, and albumin transit in EC monolayers exposed to hypoxia/reoxygenation. We conclude that prolonged hypoxia increases both XO and XD activity in EC and may predispose the endothelium to oxidative and inflammatory damage.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

Tungsten treatment prevents tumor necrosis factor-induced injury of brain endothelial cells.

Exposure to recombinant human tumor necrosis factor-alpha (TNF-alpha) or calcium ionophore (A23187) for 4 h increased (P less than 0.05) lactate dehydrogenase (LDH) release from cultured bovine brain endothelial cells (EC). In contrast, treatment with endotoxin or interleukin-1 did not increase (P greater than 0.05). LDH release from brain EC. Pretreatment with tungsten decreased (P less than 0.05) xanthine oxidase activity in brain EC and decreased (P less than 0.05) LDH release from brain EC following exposure to TNF. Our results suggest that TNF-alpha injures brain microvascular EC and that this effect may be mediated by xanthine oxidase.

Animals↗
PubMed1992

Neutrophils contribute to TNF induced myocardial tolerance to ischaemia.

Sublethal endotoxin (ETX) pretreatment of rats induces protection from cardiac ischaemia-reperfusion injury. This protective state is associated with increased endogenous myocardial catalase activity. Since tumour necrosis factor (TNF) is one mediator of ETX effects, we hypothesized that (TNF) pretreatment of the rat (30 micrograms/kg ip) 36 h prior to cardiac ischaemia-reperfusion could induce myocardial protection. We found that TNF administration increased both myocardial tolerance to ischaemia reperfusion injury (modified Langendorff, buffer perfusion, global, normothermic ischaemia) and myocardial catalase activity at 36 h. Moreover, we found that 6 h after TNF administration, myocardial hydrogen peroxide (H2O2, assessed by aminotriazole-H2O2 inactivation of catalase) and myocardial neutrophil accumulation (assessed by histology) were both increased. When neutrophil function was inhibited either by neutrophil depletion (vinblastine) or by ibuprofen treatments of the rat before TNF, the protection previously apparent at 36 h was blocked. We conclude that TNF can induce myocardial resistance to ischaemia reperfusion injury. This protection is related to prior tissue neutrophil accumulation and concomitant increases in H2O2 levels.

Animals↗
PubMed1992

Progressive increases in serum catalase activity in advancing human immunodeficiency virus infection.

We found that serum from individuals with Acquired Immunodeficiency Syndrome (AIDS) had more (p less than .05) catalase activity (31.5 +/- 5.2 U/mL) than serum from healthy control subjects (7.3 +/- 0.8 U/mL). Moreover, serum catalase (but not glutathione peroxidase) activity increased progressively with advancing human immunodeficiency virus (HIV) infection (i.e., AIDS greater than symptomatic infection greater than asymptomatic infection greater than controls). Increases in serum catalase activity correlated with increases in serum hydrogen peroxide (H2O2) scavenging ability and reached levels which decreased exogenous H2O2-mediated injury to cultured endothelial cells without altering neutrophil bactericidal activity or mononuclear cell cytotoxicity in vitro. Serum catalase activity correlated with serum lactate dehydrogenase (LDH) activity but did not appear to be a consequence of erythrocyte (RBC) hemolysis since RBC fragility and serum haptoglobin levels were comparable in HIV-infected and control subjects. Increases in serum catalase activity may reflect and/or compensate for systemic glutathione and other antioxidant deficiencies in HIV-infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Mild renal ischemia activates primed neutrophils to cause acute renal failure.

The role of neutrophils (PMN) in acute renal failure (ARF) is controversial. Although the development of acute renal failure (ARF) frequently occurs in situations where there is partial activation of PMN (primed PMN) and mild renal ischemia, the interaction between primed PMN and ischemic organs has not been studied in any biological system. To define the interaction between primed PMN and mild renal ischemia, kidneys were made ischemic for 10 minutes in situ and reperfused by the isolated kidney technique with untreated PMN or PMN primed with low concentrations of lipopolysaccharide (LPS) or phorbol myristate acetate (PMA). We found that primed PMN had no effect on control (non-ischemic) kidneys and that untreated PMN did not cause injury to kidneys previously subjected to mild ischemia. However, addition of primed PMN to mildly ischemic kidneys caused severe injury. To determine the nature of renal injury, ischemic kidneys were reperfused with primed PMN and catalase (CAT) or the elastase inhibitor, Eglin C. In ischemic kidneys reperfused with LPS-primed PMN, Eglin C (but not CAT) was partially protective while in ischemic kidneys reperfused with PMA-primed PMN, CAT (but not Eglin C) was partially protective. Reperfusion with both CAT and Eglin C completely prevented the damaging effects of either LPS- or PMA-primed PMN. In conclusion, addition of primed but not untreated PMN causes ARF in mildly ischemic kidneys by PMN oxidant- and/or protease-mediated mechanisms. This synergism could account for the high frequency of ARF in conditions associated with prerenal azotemia and primed PMN.

Acute Kidney Injury↗
PubMed1992

Circulating xanthine oxidase mediates lung neutrophil sequestration after intestinal ischemia-reperfusion.

Injury to nonpulmonary organ systems often initiates systemic processes that cause recruitment of neutrophils to the lung. We found that rats subjected to intestinal ischemia-reperfusion (I/R) had increased transvascular leak of 125I-labeled albumin into lungs and decreased lung ATP levels (P less than 0.05). In addition, rats subjected to intestinal I/R had increased plasma xanthine oxidase (XO) activity, plasma leukotactic activity for neutrophils, and lung neutrophil retention (assessed by morphometry and myeloperoxidase activity) compared with sham-treated rats (P less than 0.05). By comparison, after intestinal I/R, rats fed an allopurinol- or tungsten-enriched diet had decreased plasma and intestinal XO activities, decreased plasma leukotacic and lung myeloperoxidase (MPO) activities, decreased lung leak, and increased lung ATP levels compared with rats fed control diets (P less than 0.05). Further studies suggested a more specific role for circulating rather than tissue XO in mediating lung neutrophil accumulation but not lung leak. Plasma XO, plasma leukotactic, and lung MPO activities, but not lung leak, increased in rats administered purified XO intravenously. In addition, plasma XO, plasma leukotactic, and lung MPO activities, but not lung leak, decreased in rats administered antisera against XO and then subjected to intestinal I/R. We conclude that circulating XO increases acutely and may contribute to pulmonary retention of neutrophils after an ischemic intestinal insult.

Allopurinol↗
PubMed1992

Increased serum catalase activity in septic patients with the adult respiratory distress syndrome.

Excessive hydrogen peroxide (H2O2) generation appears to contribute to the development of the adult respiratory distress syndrome (ARDS), but H2O2-combatting antioxidant defenses have not been evaluated. We found that serum from septic patients with ARDS scavenged more (p less than 0.05) H2O2 in vitro (82.7 +/- 3.8%) than did serum from septic patients without ARDS (56.9 +/- 3.1%) or control subjects (20.2 +/- 2.4%). Serum from septic patients with ARDS also had more (p less than 0.05) catalase activity (54.9 +/- 10.9 U/ml) than did serum from septic patients without ARDS (28.6 +/- 3.4 U/ml) or control subjects (7.3 +/- 0.8 U/ml). In contrast, serum from septic patients with or without ARDS and control subjects had the same glutathione peroxidase (GPX) activity. Serum H2O2 scavenging activity correlated with serum catalase (r = 0.77) but not GPX (r = 0.33) activity and was inhibitable (greater than 90%) by sodium azide, a catalase inhibitor. Increases in serum catalase activity did not appear to be derived from erythrocytes (RBC) because septic patients with or without ARDS and control subjects had similar RBC hemolysis in response to osmotic stress in vitro and serum haptoglobin concentrations. Serum from septic patients with ARDS also protected endothelial cells against H2O2-mediated damage (34.5 +/- 2.2% 51Cr release) better (p less than 0.05) than serum from septic patients without ARDS (47.3 +/- 7.4%) or control subjects (82.1 +/- 10.2%), but killing of bacteria by neutrophils in vitro was the same in serum from patients and control subjects. Our findings indicate that patients with sepsis and/or ARDS have increased serum catalase activity, which may alter H2O2-dependent processes.

Bacterial Infections↗
PubMed1992

Dimethyl sulfoxide decreases lung neutrophil sequestration and lung leak.

To investigate basic mechanisms of acute edematous lung injury (adult respiratory distress syndrome), the formylated tripeptide formyl-norleucyl-leucyl-phenylalanine (FNLP) was instilled intratracheally into hamsters. Intratracheal FNLP produced time-dependent and dose-dependent increases in neutrophils recoverable by lung lavage (neutrophil alveolitis) and leak of intravenously injected albumin into the extravascular lung space (lung leak). Treatment with dimethyl sulfoxide (DMSO) decreased (p less than 0.05) neutrophil alveolitis and lung leak in hamsters given FNLP intratracheally. The effect of DMSO on various neutrophil functions was also studied in vitro. Addition of DMSO at concentrations (about 0.20%) measured in plasma of hamsters given DMSO decreased (p less than 0.05) neutrophil chemotaxis but not neutrophil superoxide anion generation or adherence to cultured endothelial cell monolayers or nylon fiber in vitro. We conclude that intratracheal FNLP causes neutrophil alveolitis and lung leak and that DMSO treatment ameliorates these processes, possibly by inhibiting neutrophil chemotaxis.

Animals↗
PubMed1992

Effects of dimethylthiourea in hyperoxic injury.

Pretreatment with a single dose of the oxygen metabolite scavenger 1,3-dimethyl-2-thiourea (DMTU) decreased hyperoxia-induced injury (as assessed by measurement of pleural effusions and increases in hematocrits and blood acid-soluble sulfhydryl levels) in rats that were exposed to hyperoxia for 48 hours. However, the degree of protection was not proportional to DMTU dose. An intermediate dose of DMTU (250 mg/kg) reduced injury more than a lower dose of 125 mg/kg and at least as effectively as the higher, widely used dose of 500 mg/kg DMTU. In contrast to its protective action with respect to hyperoxic injury, none of the doses of DMTU that were tested decreased the elevations in lung oxidized glutathione levels or oxidized glutathione/reduced glutathione ratios associated with hyperoxia exposure. These findings indicate that maximal protection from hyperoxic injury may be achieved with doses of DMTU that are lower than the doses used routinely. The failure of DMTU to decrease lung oxidized glutathione and lung oxidized glutathione/reduced glutathione ratio increases after hyperoxia exposure suggests that the mechanism by which DMTU confers protection requires careful evaluation.

Animals↗
PubMed1991

Oxidant-antioxidant balance: some observations from studies of ischemia-reperfusion in isolated perfused rat hearts.

Alteration in oxidant-antioxidant balance is a key feature of many common vascular diseases. Using an isolated perfused heart model, we found that (a) xanthine oxidase-derived oxygen radicals contributed to ischemia-reperfusion injury; (b) addition of antioxidants within or outside erythrocytes decreased injury following ischemia-reperfusion; (c) endotoxin pretreatment increased myocardial catalase activity and decreased injury following ischemia-reperfusion; (d) interleukin pretreatment increased myocardial glucose-6-phosphate activity and decreased ischemia-reperfusion injury, and (e) neutrophils mediated tolerance to a subsequent oxidative stress by causing a small oxidant stress that in turn increased antioxidant protection mechanisms.

Animals↗
PubMed1991

Generation of superoxide anion by brain endothelial cell xanthine oxidase.

Bovine brain endothelial cells (EC) that were isolated and propagated in pure culture had increased (greater than 20-fold) levels of xanthine oxidase and xanthine dehydrogenase activity compared to whole brain homogenate. Brain EC also released superoxide anion (O2-) into the extracellular medium. Treatment of EC with tungsten decreased (P less than 0.05) both XO activity and O2- release. XO appears to be highly concentrated in cerebral vascular endothelium and may be an important source of O2-.

Animals↗
PubMed1991

Inactivation of xanthine oxidase by hydrogen peroxide involves site-directed hydroxyl radical formation.

The mechanism of xanthine oxidase (XO) inactivation by hydrogen peroxide (H2O2) and its biologic significance are unclear. We found that addition of increasing concentrations of H2O2 progressively decreased xanthine oxidase activity in the presence but not the absence of xanthine in vitro. Inactivation of XO by H2O2 was also enhanced by anaerobic reduction of XO by xanthine. Inactivation of XO by H2O2 was accompanied by production of hydroxyl radical (.OH), measured as formation of formaldehyde from dimethylsulfoxide (DMSO). In contrast, addition of H2O2 to deflavo XO did not produce .OH. Inactivation of XO by H2O2 was decreased by simultaneous addition of the .OH scavenger, DMSO. However, inactivation of XO by H2O2 and formation of .OH were not decreased following addition of the metal chelator. DETAPAC, and/or the O2 scavenger, superoxide dismutase. The results suggest that inactivation of XO by H2O2 occurs by production of .OH following direct reduction of H2O2 by XO at the flavin site.

Dimethyl Sulfoxide↗
PubMed1991

Hypoxia increases production of interleukin-1 and tumor necrosis factor by human mononuclear cells.

Exposure to hypoxia (PO2 = 9 +/- 1 torr) increased human peripheral blood mononuclear cell production and secretion of interleukin-1 (IL-1)alpha, IL-1 beta, and tumor necrosis factor (TNF) percent of control = 190% for IL-1 alpha, p = 0.014; 219% for IL-1 beta, p = 0.014; and 243% for TNF, p = 0.037) following treatment with endotoxin (1 ng/ml). Hypoxia potentiated the increased production of these inflammatory cytokines at subthreshold levels of endotoxin with potentiation increasing at lower O2 concentrations. Hypoxia also increased cytokine production induced by the tumor promoter phorbol myristate acetate, suggesting a generalized biologic response. We conclude that hypoxia increases IL-1 and TNF production and speculate that this mechanism aggravates a variety of pathologic conditions involving endotoxin such as adult respiratory distress syndrome (ARDS), multiple organ failure, and septic shock.

Cells, Cultured↗
PubMed1991

Role of neutrophil derived oxidants and elastase in lipopolysaccharide-mediated renal injury.

Gram-negative bacterial sepsis is frequently associated with acute renal failure but the specific effects of lipopolysaccharide (LPS) and other bacterial products on kidney function are not known. Since either LPS or formyl-methionyl-leucyl-phenylalanine (FMLP)--a chemotactic peptide from bacterial cell walls--activate neutrophils (PMN) to release a number of potentially toxic factors in vitro, we determined the effect of adding PMN with LPS and/or FMLP to isolated perfused rat kidneys. Isolated rat kidneys perfused with LPS alone or LPS and normal PMN had normal glomerular filtration rates (GFR) and tubular Na reabsorption (TNa). Kidneys perfused with FMLP alone or FMLP and normal PMN also had normal GFR and TNa. In contrast, addition of PMN with both FMLP and LPS caused progressive renal dysfunction. For example, after 60 minutes of perfusion, GFR was reduced from 610 +/- 31 to 147 +/- 17 microliters/min/g and TNa from 97 +/- 1 to 72 +/- 2%, both P less than 0.01. Perfusion with the O2 metabolite scavengers catalase or dimethylthiourea afforded no protection while perfusion with the neutrophil elastase inhibitor Eglin C conferred substantial, but not complete, protection: GFR 492 +/- 34 microliters/min/g; TNa 91 +/- 3%. However, perfusion with both Eglin C and catalase completely prevented the toxic effects of LPS and FMLP-treated PMN on renal function. We conclude that in isolated kidneys, 1) the toxic effects of LPS requires FMLP-treated PMN and that 2) LPS and FMLP treated PMN cause progressive renal injury which is mediated by both O2 metabolites and neutrophil elastase.

Animals↗
PubMed1991

Disparate antioxidant enzyme activities in cultured human cutaneous fibroblasts, keratinocytes, and melanocytes.

Antioxidant enzyme activities of cultured human foreskin fibroblasts, keratinocytes, and melanocytes from healthy black and Caucasian donors were measured and compared. Fibroblasts had more (p less than 0.05) peroxidase, catalase, glutathione peroxidase, and superoxide dismutase activity than keratinocytes. Keratinocytes had more (p less than 0.05) peroxidase, catalase, glutathione peroxidase, and superoxide dismutase activity than melanocytes. No differences in antioxidant enzyme activities were observed between the cells of any type taken from black or Caucasian people. Antioxidant enzyme activities may affect resistance to damage by oxidants induced by ultraviolet radiation and inflammation.

Catalase↗
PubMed1991

Existence and participation of xanthine oxidase in reperfusion injury of ischemic rabbit myocardium.

Using a highly specific assay that minimizes enzyme inactivation in vitro, we found that rabbit myocardial tissue contained low levels of xanthine oxidase (XO) and xanthine dehydrogenase (XD) activity that were effectively inhibited by pretreatment of hearts with allopurinol. In parallel, allopurinol treatment also improved ventricular developed pressure, peak systolic pressure, and coronary flow in isolated hearts subjected to 30 min of normothermic global ischemia and 30 min of reperfusion. Although function was protected by allopurinol treatment, creatine kinase (CK) release was not altered by allopurinol. Inhibition of myocardial XO with allopurinol did not increase myocardial ATP or phosphocreatine. In addition, allopurinol did not scavenge superoxide anion or hydrogen peroxide in vitro. The results support the possibility that relatively low amounts of XO activity, similar to levels reported in human myocardium, may contribute to cardiac ischemia-reperfusion injury.

Allopurinol↗
PubMed1991

FNLP injures endotoxin-primed rat lung by neutrophil-dependent and -independent mechanisms.

Bacterial lipopolysaccharide (LPS) and an N-formyl peptide, N-formyl-neoleucyl-leucyl-phenylalanine (FNLP), synergistically promote lung injury in rats as measured by 125I-labeled albumin flux. Concomitantly, neutrophils are sequestered in the lung. We hypothesized that LPS-FNLP-induced lung injury is mediated both by neutrophil-dependent and -independent mechanisms. Rats were depleted of circulating and marginating neutrophils with vinblastine. LPS-FNLP-induced lung protein leak was partially decreased in these neutrophil-depleted animals, although a component of lung injury remained. We hypothesized that LPS-FNLP-induced lung injury was also mediated by xanthine oxidase (XO). Rats were fed a tungsten-enriched diet that inactivates molybdenum-dependent oxidase systems. LPS-FNLP-induced lung leak was partially decreased in these animals as well. When tungsten-fed rats were also neutrophil depleted with vinblastine, no increase in 125I-albumin flux was observed in response to LPS-FNLP. In parallel experiments, lungs from vinblastine-pretreated rats were isolated and perfused. FNLP infusion into the LPS-primed, crystalloid-perfused lungs caused increased 125I-albumin flux, which was prevented by oxidase inhibition. We conclude that LPS-FNLP-induced lung injury is both neutrophil mediated and neutrophil independent. The nonneutrophil component of the LPS-FNLP-induced lung injury appears to be pulmonary XO derived and dependent.

Animals↗