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S Matalon

Publications and source records attributed to S Matalon.

At least 37 records · Page 2Linked to original sources
PubMed2000

Protein nitration, metabolites of reactive nitrogen species, and inflammation in lung allografts.

This study investigated nitration and chlorination of epithelial lining fluid (ELF) proteins in patients (n = 29) who had undergone lung allotransplantation. We assayed lung lavage nitrotyrosine (NT) and chlorotyrosine (CT) by HPLC. We measured NT, nitrate (NO(3)(-)), and nitrate (NO(2)(-)) in bronchoalveolar lavage fluid (BALF) and total nitrite (NO(2)(-) + NO(3)(-)) in serum of another group of lung transplant patients (n = 82). In the first group (n = 29), percent nitration of tyrosines (Tyr) (NT/total Tyr x 100) in BALF proteins was: patients, 0.01 (0.00-0.12)%; median (25th-75th% confidence interval), and control subjects 0.01 (0.00-0.02)%. CT (CT/ total Tyr x 100) occurred only in the patients' BALF: 0.01 (0. 00- 0.02)%. In the second group (n = 82), nitrotyrosine (NT) was detected by ELISA in the BALF of patients: 9 (0-41) pmol/mg pro and control subjects: 28 (26-33). Total nitrite (NO(2)(-) + NO(3)(-)) in BALF of the patients: 3.3 (1.9-5.1) microM significantly exceeded that in control subjects: 1.3 (0.8-1.3) microM; p = 0.0133. Serum nitrite also was significantly higher in patients: 37 (26-55) microM than control subjects: 19 (17-20) microM; p = 0.0037. Airway inflammation in transbronchial biopsies (B score) correlated with NT in BALF (p = 0.0369). Lung transplants have increased airway concentrations of reactive nitrogen species (RNS) metabolites. NT, a marker of peroxynitrite (ONOO(-)), is related to the degree of airway inflammation in lung transplants.

Adult↗
PubMed2000

Cyclophosphamide prevents systemic keratinocyte growth factor-induced up-regulation of surfactant protein A after allogeneic transplant in mice.

We reported that systemic keratinocyte growth factor (KGF) given before bone marrow transplantation (BMT) prevents allogeneic T cell-dependent lung inflammation assessed on Day 7 post-BMT, but the antiinflammatory effects of KGF were impaired in mice injected with both T cells and conditioning regimen of cyclophosphamide (Cy). Intratracheal KGF is known to stimulate the expression of surfactant protein A (SP-A), an oxidant-sensitive T cell immunomodulator produced by alveolar type II cells. We hypothesized that systemic KGF up-regulates SP-A after allogeneic BMT, and the addition of Cy may interfere with the ability of KGF to enhance SP-A production. The subcutaneous administration of recombinant human KGF (5 mg/kg on Days -6, -5, and -4 pre-BMT) increased SP-A protein and mRNA in allogeneic T cell-recipient irradiated mice measured on Day 7 post-BMT. In contrast, the same KGF treatment in irradiated mice given T cells and Cy failed to up-regulate SP-A mRNA and protein expression. In mixed lymphocyte reaction experiments designed to simulate the in vivo model, the addition of human SP-A (5-50 microg) to alloactivated T cells suppressed the production of interleukin-2 in a dose-dependent fashion. We conclude that the systemic pre-BMT injection of KGF in recipients of allogeneic T cells up-regulates SP-A, which may contribute to the early antiinflammatory effects of KGF. The protective KGF-mediated SP-A production is abolished in mice given alloreactive T cells plus Cy.

Animals↗
PubMed1999

Biochemical characterization of human S-nitrosohemoglobin. Effects on oxygen binding and transnitrosation.

S-Nitrosation of cysteine beta93 in hemoglobin (S-nitrosohemoglobin (SNO-Hb)) occurs in vivo, and transnitrosation reactions of deoxygenated SNO-Hb are proposed as a mechanism leading to release of NO and control of blood flow. However, little is known of the oxygen binding properties of SNO-Hb or the effects of oxygen on transnitrosation between SNO-Hb and the dominant low molecular weight thiol in the red blood cell, GSH. These data are important as they would provide a biochemical framework to assess the physiological function of SNO-Hb. Our results demonstrate that SNO-Hb has a higher affinity for oxygen than native Hb. This implies that NO transfer from SNO-Hb in vivo would be limited to regions of extremely low oxygen tension if this were to occur from deoxygenated SNO-Hb. Furthermore, the kinetics of the transnitrosation reactions between GSH and SNO-Hb are relatively slow, making transfer of NO+ from SNO-Hb to GSH less likely as a mechanism to elicit vessel relaxation under conditions of low oxygen tension and over the circulatory lifetime of a given red blood cell. These data suggest that the reported oxygen-dependent promotion of S-nitrosation from SNO-Hb involves biochemical mechanisms that are not intrinsic to the Hb molecule.

Allosteric Regulation↗
PubMed1999

Surfactant protein A mediates mycoplasmacidal activity of alveolar macrophages by production of peroxynitrite.

We have previously shown that surfactant protein A (SP-A) mediates in vitro killing of mycoplasmas by alveolar macrophages (AMs) from resistant C57BL/6 mice through a nitric oxide (.NO)-dependent mechanism. Herein, SP-A-deficient [SP-A(-/-)] and inducible.NO synthase-deficient [iNOS(-/-)] mice were infected intranasally with 10(5) or 10(7) colony-forming units of Mycoplasma pulmonis. SP-A(-/-) mice were as susceptible to mycoplasmal infection as highly susceptible C3H/He mice, and far more susceptible than resistant C57BL/6 mice. iNOS(-/-) mice had significantly greater numbers of mycoplasmas and severity of lung lesions than iNOS(+/+) controls. In vitro, AMs isolated from C57BL/6 mice, activated with IFN-gamma, incubated with SP-A (25 micrograms/ml), and infected with 10(10) colony-forming units of M. pulmonis, killed mycoplasmas within 6 h. Mycoplasmal killing was abrogated by 1,000 units/ml of copper-zinc superoxide dismutase. In the absence of AMs, incubation of M. pulmonis with the peroxynitrite generator 3-morpholinosynodiomine.HCl (SIN-1) effected complete killing of mycoplasmas by 90 min in a dose-dependent manner. Addition of copper-zinc superoxide dismutase (3,000 units/ml), which converts SIN-1 to a.NO donor, prevented this killing. Neither of the reactive oxygen species generated by xanthine oxidase (10 milliunits/ml, plus 500 microM xanthine and 100 microM FeCl3), nor.NO generated by 1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine (PAPA NONOate) (100 microM) killed mycoplasmas. These data establish that peroxynitrite generation by AMs is necessary for the killing of a pathogen in vitro and in vivo.

Animals↗
PubMed1999

Extreme, progressive isovolemic hemodilution with 5% human albumin, PentaLyte, or Hextend does not cause hepatic ischemia or histologic injury in rabbits.

BACKGROUND: Physicians and their patients are greatly concerned about perioperative blood administration. Although isovolemic hemodilution is utilized to decrease the incidence of transfusion, it is unclear at what degree of hemodilution hepatoenteric ischemia and injury occurs. The authors hypothesized that hepatic ischemia, systemic ischemia, and tissue injury would occur during hemodilution in rabbits, and that the severity of ischemia and injury may be dependent on the fluid administered. METHODS: Rabbits anesthetized with isoflurane were assigned randomly to a sham-operated group (n = 8) or groups that underwent four isovolemic hemodilutions (25% of the blood volume removed at hourly intervals), with blood replaced with one of three solutions: balanced electrolyte solutions containing 6% pentastarch (n = 8), 6% hetastarch (n = 9), or 5% human albumin in normal saline (n = 8). Arterial ketone body ratio and plasma lactate, respectively, served as measures of hepatic and systemic ischemia. Gastric, duodenal, and hepatic histologic injury was assessed post mortem. RESULTS: Hemodilution from a baseline hematocrit of about 33% to about 8% (third hemodilution) with all three colloids did not result in a significant increase in plasma lactate concentration or decrease in arterial ketone body ratio. At a hematocrit of about 5% (fourth hemodilution), the hetastarch group had a significantly (P < 0.05) greater plasma lactate concentration than the sham-operated and 5% human albumin groups. There were no significant differences in arterial ketone body ratio or histologic injury between the groups. CONCLUSIONS: Isovolemic hemodilution (approximately 5% hematocrit) with albumin, pentastarch, or hetastarch solutions does not result in significant hepatic ischemia or injury assessed by histology.

Animals↗
PubMed1999

Sodium channels in alveolar epithelial cells: molecular characterization, biophysical properties, and physiological significance.

At birth, fetal distal lung epithelial (FDLE) cells switch from active chloride secretion to active sodium (Na+) reabsorption. Sodium ions enter the FDLE and alveolar type II (ATII) cells mainly through apical nonselective cation and Na(+)-selective channels, with conductances of 4-26 pS (picoSiemens) in FDLE and 20-25 pS in ATII cells. All these channels are inhibited by amiloride with a 50% inhibitory concentration of < 1 microM, and some are also inhibited by [N-ethyl-N-isopropyl]-2'-4'-amiloride (50% inhibitory concentration of < 1 microM). Both FDLE and ATII cells contain the alpha-, beta-, and gamma-rENaC (rat epithelial Na+ channels) mRNAs; reconstitution of an ATII cell Na(+)-channel protein into lipid bilayers revealed the presence of 25-pS Na+ single channels, inhibited by amiloride and [N-ethyl-N-isopropyl]-2'-4'-amiloride. A variety of agents, including cAMP, oxygen, glucocorticoids, and in some cases Ca2+, increased the activity and/or rENaC mRNA levels. The phenotypic properties of these channels differ from those observed in other Na(+)-absorbing epithelia. Pharmacological blockade of alveolar Na+ transport in vivo, as well as experiments with newborn alpha-rENaC knock-out mice, demonstrate the importance of active Na+ transport in the reabsorption of fluid from the fetal lung and in reabsorbing alveolar fluid in the injured adult lung. Indeed, in a number of inflammatory diseases, increased production of reactive oxygen-nitrogen intermediates, such as peroxynitrite (ONOO-), may damage ATII and FDLE Na+ channels, decrease Na+ reabsorption in vivo, and thus contribute to the formation of alveolar edema.

Animals↗
PubMed1999

Nitric oxide inhibits heterologous CFTR expression in polarized epithelial cells.

Nitric oxide (. NO) has been implicated in a wide range of autocrine and paracrine signaling mechanisms. Herein, we assessed the role of exogenous. NO in the modulation of heterologous gene expression in polarized kidney epithelial cells (LLC-PK(1)) that were stably transduced with a cDNA encoding human wild-type cystic fibrosis transmembrane conductance regulator (CFTR) under the control of a heavy metal-sensitive metallothionein promoter (LLC-PK(1)-WTCFTR). Exposure of these cells to 125 microM DETA NONOate at 37 degrees C for 24 h (a chemical. NO donor) diminished Zn(2+)-induced and uninduced CFTR protein levels by 43.3 +/- 5.1 and 34.4 +/- 17.1% from their corresponding control values, respectively. These changes did not occur if red blood cells, effective scavengers of. NO, were added to the medium. Exposure to. NO did not alter lactate dehydrogenase release in the medium or the extent of apoptosis. Coculturing LLC-PK(1)-WTCFTR cells with murine fibroblasts that were stably transduced with the human inducible. NO synthase cDNA gene also inhibited CFTR protein expression in a manner that was antagonized by 1 mM N(G)-monomethyl-L-arginine in the medium. Pretreatment of LLC-PK(1)-WTCFTR with ODQ, an inhibitor of guanylyl cyclase, did not affect the ability of. NO to inhibit heterologous CFTR expression; furthermore, 8-bromo-cGMP had no effect on heterologous CFTR expression. These data indicate that. NO impairs the heterologous expression of CFTR in epithelial cells at the protein level via cGMP-independent mechanisms.

3T3 Cells↗
PubMed1998

Asbestos inhalation induces reactive nitrogen species and nitrotyrosine formation in the lungs and pleura of the rat.

To determine whether asbestos inhalation induces the formation of reactive nitrogen species, three groups of rats were exposed intermittently over 2 wk to either filtered room air (sham-exposed) or to chrysotile or crocidolite asbestos fibers. The rats were killed at 1 or 6 wk after exposure. At 1 wk, significantly greater numbers of alveolar and pleural macrophages from asbestos-exposed rats than from sham-exposed rats demonstrated inducible nitric oxide synthase protein immunoreactivity. Alveolar macrophages from asbestos-exposed rats also generated significantly greater nitrite formation than did macrophages from sham-exposed rats. Strong immunoreactivity for nitrotyrosine, a marker of peroxynitrite formation, was evident in lungs from chrysotile- and crocidolite-exposed rats at 1 and 6 wk. Staining was most evident at alveolar duct bifurcations and within bronchiolar epithelium, alveolar macrophages, and the visceral and parietal pleural mesothelium. Lungs from sham-exposed rats demonstrated minimal immunoreactivity for nitrotyrosine. Significantly greater quantities of nitrotyrosine were detected by ELISA in lung extracts from asbestos-exposed rats than from sham-exposed rats. These findings suggest that asbestos inhalation can induce inducible nitric oxide synthase activation and peroxynitrite formation in vivo, and provide evidence of a possible alternative mechanism of asbestos-induced injury to that thought to be induced by Fenton reactions.

Animals↗
PubMed1998

Peroxynitrite inhibits amiloride-sensitive Na+ currents in Xenopus oocytes expressing alpha beta gamma-rENaC.

We examined the effect of peroxynitrite (ONOO-) on the cloned rat epithelial Na+ channel (alpha beta gamma-rENaC) expressed in Xenopus oocytes. 3-Morpholinosydnonimine (SIN-1) was used to concurrently generate nitric oxide (.NO) and superoxide (O2-.), which react to form ONOO-, a species known to promote protein nitration and oxidation. Under control conditions, oocytes displayed an amiloride-sensitive whole cell conductance of 7.4 +/- 2.8 (SE) microS. When incubated at 18 degrees C with SIN-1 (1 mM) for 2 h (final ONOO- concentration = 10 microM), the amiloride-sensitive conductance was reduced to 0.8 +/- 0.5 microS. To evaluate whether the observed inhibition was due to ONOO-, as opposed to .NO, we also exposed oocytes to SIN-1 in the presence of urate (500 microM), a scavenger of ONOO- and superoxide dismutase, which scavenges O2-., converting SIN-1 from an ONOO- to an .NO donor. Under these conditions, conductance values remained at control levels following SIN-1 treatment. Tetranitromethane, an agent that oxidizes sulfhydryl groups at pH 6, also inhibited the amiloride-sensitive conductance. These data suggest that oxidation of critical sulfhydryl groups within rENaC by ONOO- directly inhibits channel activity.

Amiloride↗
PubMed1998

Hydrogen peroxide inhibits cAMP-induced Cl- secretion across colonic epithelial cells.

We examined the effects of H2O2 on Cl- secretion across human colonic T84 cells grown on permeable supports and mounted in modified Ussing chambers. Forskolin-induced short-circuit current, a measure of Cl- secretion, was inhibited in a concentration-dependent fashion when monolayers were pretreated with H2O2 for 30 min (30-100% inhibition between 500 microM and 5 mM). Moreover, H2O2 inhibited 76% of the Cl- current across monolayers when the basolateral membranes were permeabilized with nystatin (200 micrograms/ml). When the apical membrane was permeabilized with amphotericin B, H2O2 inhibited the Na+ current (a measure of Na+-K+-ATPase activity) by 68% but increased the K+ current more than threefold. In addition to its effects on ion transport pathways, H2O2 also decreased intracellular ATP levels by 43%. We conclude that the principal effect of H2O2 on colonic Cl- secretion is inhibitory. This may be due to a decrease in ATP levels following H2O2 treatment, which subsequently results in an inhibition of the apical membrane Cl- conductance and basolateral membrane Na+-K+-ATPase activity. Alternatively, H2O2 may alter Cl- secretion by direct action on the transporters or alterations in signal transduction pathways.

Adenosine Triphosphate↗
PubMed1998

Surfactant protein A mediates mycoplasmacidal activity of alveolar macrophages.

Mycoplasma pneumoniae is a leading cause of pneumonia and exacerbates other respiratory diseases in humans. We investigated the potential role of surfactant protein (SP) A in antimycoplasmal defense using alveolar macrophages (AMs) from C57BL/6NCr (C57BL) mice, which are highly resistant to infections of Mycoplasma pulmonis. C57BL AMs, activated with interferon (IFN)-gamma and incubated with SP-A (25 micrograms/ml) at 37 degrees C, produced significant amounts of nitric oxide (.NO; nitrate and nitrite production = 1.1 microM.h-1.10(5) AMs-1) and effected an 83% decrease in mycoplasma colony-forming units (CFUs) by 6 h postinfection. Preincubation of AMs with the inducible nitric oxide synthase inhibitor NG-monomethyl-L-arginine abolished .NO production and SP-A-mediated killing of mycoplasmas. No decrease in CFUs was seen when IFN-gamma-activated macrophages were infected with mycoplasmas in the absence of SP-A despite significant .NO production (nitrate and nitrite production = 0.6 microM.h-1.10(5) AMs-1). These results demonstrate that SP-A mediates killing of mycoplasmas by AMs, possibly through an .NO-dependent mechanism.

Animals↗
PubMed1998

Nitric oxide inhibits Na+ absorption across cultured alveolar type II monolayers.

We examined the mechanisms by which nitric oxide (.NO) decreased vectorial Na+ transport across confluent monolayers of rat alveolar type II (ATII) cells grown on permeable supports. Amiloride (10 microM) applied to the apical side of monolayers inhibited approximately 90% of the equivalent (Ieq) and the short-circuit (Isc) current, with an half-maximal inhibitory concentration (IC50) of 0.85 microM, indicating that Na+ entry into ATII cells occurred through amiloride-sensitive Na+ channels. .NO generated by spermine NONOate and papa NONOate added to both sides of the monolayers decreased Ieq and increased transepithelial resistance in a concentration-dependent fashion (IC50 = 0.4 microM .NO). These changes were prevented or reversed by addition of oxyhemoglobin (50 microM). Incubation of ATII monolayers with 8-bromoguanosine 3',5'-cyclic monophosphate (400 microM) had no effect on transepithelial Na+ transport. When the basolateral membranes of ATII cells were permeabilized with amphotericin B (10 microM) in the presence of a mucosal-to-serosal Na+ gradient (145:25 mM), .NO (generated by 100 microM papa NONOate) inhibited approximately 60% of the amiloride-sensitive Isc. In addition, after permeabilization of the apical membranes, .NO inhibited the Isc [a measure of Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity] by approximately 60%. We concluded that .NO at noncytotoxic concentrations decreased Na+ absorption across cultured ATII monolayers by inhibiting both the amiloride-sensitive Na+ channels and Na(+)-K(+)-ATPase through guanosine 3',5'-cyclic monophosphate-independent mechanisms.

Absorption↗
PubMed1998

Nitrated SP-A does not enhance adherence of Pneumocystis carinii to alveolar macrophages.

We investigated whether nitration of surfactant apoprotein (SP) A alters its ability to bind to mannose-containing saccharides on Pneumocystis carinii and its potential role in the mediation of P. carinii adherence to alveolar macrophages. Human SP-A was nitrated by incubation with tetranitromethane at pH 8.0 or synthetic peroxynitrite (ONOO-) at pH 7.4, which resulted in significant nitration of tyrosines in its carbohydrate recognition domain [0.63 +/- 0.001 (SE) and 1.25 +/- 0.02 mol nitrotyrosine/mol monomeric SP-A, respectively; n = 3 samples]. Binding of SP-A to P. carinii was calcium dependent and competitively inhibited by alpha-methyl-D-mannopyranoside. Nitration of SP-A by ONOO- or tetranitromethane decreases its binding to P. carinii by increasing its dissociation constant from 7.8 x 10(-9) to 1.6 x 10(-8) or 2.4 x 10(-8) M, respectively, without significantly affecting the number of binding sites (7.1 x 10(6)/P. carinii organisms, assuming that the native molecular mass of oligomeric SP-A is 650 kDa). Furthermore, ONOO--nitrated SP-A failed to mediate the adherence and phagocytosis of P. carinii to rat alveolar macrophages as observed with normal SP-A. Binding of SP-A to rat alveolar macrophages was not altered by nitration. These results indicate that nitration of SP-A interferes with its ability to serve as a ligand for P. carinii adherence to alveolar macrophages at the site of the SP-A moleculeP. carinii interaction.

Animals↗
PubMed1998

cAMP activation of chloride and fluid secretion across the rabbit alveolar epithelium.

Active Na+ transport by alveolar epithelial cells has been demonstrated to contribute significantly to alveolar fluid clearance. However, the contribution of transepithelial Cl- movement to the reabsorption of isosmotic fluid across the alveolar epithelium in vivo has not been elucidated. We hypothesized that Cl- transport could be increased across the alveolar epithelium in vivo and across cultured alveolar type II cells by agents that increase intracellular cAMP (e.g., forskolin). In studies where 5% albumin in sodium methanesulfonate (a Cl--free solution) was administered into the lung, forskolin administration significantly increased intracellular influx of Cl- and fluid into the alveolar space. In vitro studies with cultured rabbit alveolar type II cell monolayers in Ussing chambers demonstrated that elevations in intracellular cAMP increase short-circuit current by increasing both Cl- secretion and Na+ reabsorption. The cystic fibrosis transmembrane conductance regulator channel blocker glibenclamide and the loop diuretic bumetanide partially decreased the forskolin-induced increase in short-circuit current. These data may explain the failure of agonist that stimulated intracellular cAMP to increase alveolar fluid clearance in the rabbit. Moreover, the data suggest that in the event Na+ absorptive pathways are damaged, transepithelial Cl- secretion and the consequent intra-alveolar fluid influx may be upregulated.

Animals↗
PubMed1998

Contribution of reactive oxygen and nitrogen species to particulate-induced lung injury.

Recently, a second pathway for the generation of potential oxidants with the reactivity of the hydroxyl radical without the need for metal catalysis has been described. In response to various inflammatory stimuli, lung endothelial, alveolar, and airway epithelial cells, as well as activated alveolar macrophages, produce both nitric oxide (.NO) and superoxide anion radicals (O2.-). .NO regulates pulmonary vascular and airway tone and plays an important role in lung host defense against various bacteria. However, .NO may be cytotoxic by inhibiting critical enzymes such as mitochondrial aconitase and ribonucleotide reductase, by S-nitrosolation of thiol groups, or by binding to their iron-sulfur centers. In addition, .NO reacts with O2.- at a near diffusion-limited rate to form the strong oxidant peroxynitrite (ONOO-), which can nitrate and oxidize key amino acids in various lung proteins such as surfactant protein A, and inhibit their functions. The presence of ONOO- in the lungs of patients with acute respiratory distress syndrome has been demonstrated by measuring levels of nitrotyrosine, the stable product of tyrosine nitration. Various studies have shown that inhalation or intratracheal instillation of various respirable mineral dusts or asbestos fibers increased levels of inducible nitric oxide synthase mRNA. In this presentation, we review the evidence for the upregulation of .NO in the lungs of animals exposed to mineral particulates and assess the contribution of reactive nitrogen species in the pathogenesis of the resultant lung injury.

Animals↗
PubMed1997

The interplay of nitric oxide and peroxynitrite with signal transduction pathways: implications for disease.

Since the discovery that at least one form of endothelium derived relaxing factor is nitric oxide (NO), numerous studies have uncovered diverse roles for this free radical in a variety of physiological and pathophysiological processes. NO production, a process mediated by a family of enzymes termed NO synthases, has been detected in most cell types. Many of the effects of NO are thought to be mediated through its direct interaction with specific and defined cell signaling pathways. The nature of such interactions are highly dependent on the concentration of NO and cell type. Furthermore, specific NO derived reaction products, such as peroxynitrite, also have the potential to effect cell signal transduction events. As with NO, this can occur through diverse mechanisms and depends on concentration and cell type. It is perhaps not surprising that the reported effects of NO in different disease states are often conflicting. In this brief overview, a framework for placing these apparently disparate properties of NO will be described and will focus on the effects of NO and peroxynitrite on signaling pathways.

Animals↗