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Sadis Matalon

Publications and source records attributed to Sadis Matalon.

17 recordsLinked to original sources
PubMed2003

cAMP-induced changes of apical membrane potentials of confluent H441 monolayers.

We recorded apical membrane potentials (Va) of H441 cells [a human lung cell line exhibiting both epithelial Na+ (ENaC) and CFTR-type channels] grown as confluent monolayers, using the microelectrode technique in current-clamp mode before, during, and after perfusion of the apical membranes with 10 microM forskolin. When perfused with normal Ringer solution, the cells had a Va of -43 +/- 10 mV (means +/- SD; n = 31). Perfusion with forskolin resulted in sustained depolarization by 25.0 +/- 3.5 mV (means +/- SD; n = 23) and increased the number, open time, and the open probability of a 4.2-pS ENaC. In contrast to a previous report (Jiang J, Song C, Koller BH, Matthay MA, and Verkman AS. Am J Physiol Cell Physiol 275: C1610-C1620, 1998), no transient hyperpolarization was observed. The forskolin-induced depolarization of Va was almost totally prevented by pretreatment of monolayers with 10 microM amiloride or by substitution of Na+ ions in the bath solution with N-methyl-d-glucamine. These findings indicate that cAMP stimulation of Na+ influx across H441 confluent monolayers results from activation of an amiloride-sensitive apical Na+ conductance and not from Va hyperpolarization due to Cl- influx through CFTR-type channels.

Amiloride↗
PubMed2003

Future research directions in acute lung injury: summary of a National Heart, Lung, and Blood Institute working group.

Acute lung injury (ALI) and its more severe form, the acute respiratory distress syndrome (ARDS), are syndromes of acute respiratory failure that result from acute pulmonary edema and inflammation. The development of ALI/ARDS is associated with several clinical disorders including direct pulmonary injury from pneumonia and aspiration as well as indirect pulmonary injury from trauma, sepsis, and other disorders such as acute pancreatitis and drug overdose. Although mortality from ALI/ARDS has decreased in the last decade, it remains high. Despite two major advances in treatment, low VT ventilation for ALI/ARDS and activated protein C for severe sepsis (the leading cause of ALI/ARDS), additional research is needed to develop specific treatments and improve understanding of the pathogenesis of these syndromes. The NHLBI convened a working group to develop specific recommendations for future ALI/ARDS research. Improved understanding of disease heterogeneity through use of evolving biologic, genomic, and genetic approaches should provide major new insights into pathogenesis of ALI. Cellular and molecular methods combined with animal and clinical studies should lead to further progress in the detection and treatment of this complex disease.

Academies and Institutes↗
PubMed2003

Hyperoxia impairs antibacterial function of macrophages through effects on actin.

Oxidative stress may impair alveolar macrophage function in patients with inflammatory lung diseases or those exposed to high concentrations of oxygen. We investigated putative mechanisms of injury to macrophages by oxidative stress, using RAW 264.7 cells exposed to 95% oxygen for 48 h. Hyperoxia-exposed macrophages were less able to phagocytose and kill Klebsiella pneumoniae than normoxic controls, despite increased production of nitric oxide, a free radical important in pathogen killing. Exposure of macrophages to hyperoxia had marked effects on the actin cytoskeleton, including increased actin polymerization, loss of cortical actin, formation of stress fibers, de novo synthesis of actin, and actin oxidation. Hyperoxia induced changes in cell morphology, with increased cell size and pseudopod formation. Exposure of macrophages to jasplakinolide, an agent that increases actin polymerization, also impaired their ability to phagocytose Klebsiella. Alveolar macrophages isolated from mice exposed to 100% oxygen for 84 h also demonstrated impaired phagocytic function, as well as similar effects on the actin cytoskeleton and cell morphology to macrophages exposed to hyperoxia in vitro. We conclude that oxidative stress in vitro and in vivo impairs macrophage antibacterial function through effects on actin.

Actins↗
PubMed2002

Inhibition of human surfactant protein A function by oxidation intermediates of nitrite.

NitraNitration of protein tyrosine residues by peroxynitrite (ONOO - ) has been implicated in a variety of inflammatory diseases such as acute respiratory distress syndrome (ARDS). Pulmonary surfactant protein A (SP-A) has multiple functions including host defense. We report here that a mixture of hypochlorous acid (HOCl) and nitrite (NO 2 - ) induces nitration, oxidation, and chlorination of tyrosine residues in human SP-A and inhibits SP-A's ability to aggregate lipids and bind mannose. Nitration and oxidation of SP-A was not altered by the presence of lipids, suggesting that proteins are preferred targets in lipid-rich mixtures such as pulmonary surfactant. Moreover, both horseradish peroxidase and myeloperoxidase (MPO) can utilize NO 2 - and hydrogen peroxide (H 2 O 2 ) as substrates to catalyze tyrosine nitration in SP-A and inhibit its lipid aggregation function. SP-A nitration and oxidation by MPO is markedly enhanced in the presence of physiological concentrations of Cl - and the lipid aggregation function of SP-A is completely abolished. Collectively, our results suggest that MPO released by activated neutrophils during inflammation utilizes physiological or pathological levels of NO 2 - to nitrate proteins, and may provide an additional mechanism in addition to ONOO - formation, for tissue injury in ARDS and other inflammatory diseases associated with upregulated *NO and oxidant production.

Bronchoalveolar Lavage Fluid↗
PubMed2002

Modulation of sodium transport in fetal alveolar epithelial cells by oxygen and corticosterone.

Regulation of active Na(+) transport across fetal distal lung epithelial cells (FDLE) by corticosterone (CST), corticotropin-releasing hormone (CRH), and oxygen tension may be crucial for postnatal adaptation. FDLE isolated from 19-day rat fetuses (term: 22 days) were grown on permeable supports to confluent monolayers (duration 3 days) in 2.5, 5, 12, or 20% O(2) with 5% CO(2)-balance N(2) and mounted in Ussing chambers for measurement of short-circuit currents (I(sc)). FDLE monolayers grown in 20% O(2) had significantly higher levels of total I(sc) and of their amiloride-sensitive (I(amil)) and ouabain-sensitive (I(ouab)) components than hypoxic cells. Values (microA/cm(2) +/- SE) for 2.5-5% O(2) and 20% O(2) were, respectively, I(sc) 5.3 +/- 0.2 vs. 8.4 +/- 0.3 (P < 0.001), I(amil) 3.4 +/- 0.2 vs. 4.3 +/- 0.2 (P < 0.01), and I(ouab) 3.4 +/- 0.6 vs. 9.1 +/- 0.6 (P < 0.001). Addition of CST but not CRH to the culture medium at any O(2) concentration increased I(amil). FDLE cells grown at 5% O(2) expressed significantly lower levels of alpha-, beta-, and gamma-epithelial Na(+) channel (ENaC), and of the alpha(1)-Na(+)-K(+)-ATPase, as determined by Western blotting. We conclude that higher O(2) concentrations increased total vectorial Na(+) transport, and the function of Na(+)-K(+)-ATPase and apical amiloride-sensitive Na(+) conductance, whereas CST only increased ENaC function.

Amiloride↗
PubMed2002

Reactive oxygen nitrogen species decrease cystic fibrosis transmembrane conductance regulator expression and cAMP-mediated Cl- secretion in airway epithelia.

We investigated putative mechanisms by which nitric oxide modulates cystic fibrosis transmembrane conductance regulator (CFTR) expression and function in epithelial cells. Immunoprecipitation followed by Western blotting, as well as immunocytochemical and cell surface biotinylation measurements, showed that incubation of both stably transduced (HeLa) and endogenous CFTR expressing (16HBE14o-, Calu-3, and mouse tracheal epithelial) cells with 100 microm diethylenetriamine NONOate (DETA NONOate) for 24-96 h decreased both intracellular and apical CFTR levels. Calu-3 and mouse tracheal epithelial cells, incubated with DETA NONOate but not with 100 microm 8-bromo-cGMP for 96 h, exhibited reduced cAMP-activated short circuit currents when mounted in Ussing chambers. Exposure of Calu-3 cells to nitric oxide donors resulted in the nitration of a number of proteins including CFTR. Nitration was augmented by proteasome inhibition, suggesting a role for the proteasome in the degradation of nitrated proteins. Our studies demonstrate that levels of nitric oxide that are likely to be encountered in the vicinity of airway cells during inflammation may nitrate CFTR resulting in enhanced degradation and decreased function. Decreased levels and function of normal CFTR may account for some of the cystic fibrosis-like symptoms that occur in chronic inflammatory lung diseases associated with increased NO production.

Animals↗
PubMed2002

Effects of variable concentrations of inhaled nitric oxide and oxygen on the lungs of newborn piglets.

We previously demonstrated that inhalation of high concentrations of nitric oxide (iNO) and oxygen for 48 hr causes significant lung injury in newborn piglets. To determine if these effects persist at lower concentrations, groups of newborn piglets were mechanically ventilated for 48 hr with (study 1) constant O(2) (90-100%) and decreasing iNO (100-2 ppm) or (study 2) constant iNO (50 ppm) and decreasing O(2) (95-30%). Bronchoalveolar lavage (BAL) fluid was assayed for surfactant function, and markers of lung inflammation and physiologic parameters were monitored. Neutrophil chemotactic activity (NCA), % neutrophils, and total protein (TP) concentrations decreased significantly in BAL fluid of study 1 piglets as iNO was reduced and inhaled oxygen fraction remained constant, indicating less pulmonary injury at low iNO levels. Low-dose iNO (2 ppm) did not have antiinflammatory effects. However, surfactant function was minimally affected by lowering iNO, and was abnormal in all groups. In contrast, in study 2, pulmonary inflammation and injury were lower when O(2) was decreased to 70% or less, with iNO constant at 50 ppm. Surfactant function normalized and oxygenation improved in study 2 piglets when the inhaled oxygen fraction was decreased and iNO remained constant. These data suggest that iNO- and O(2)-induced lung injury may be minimized by weaning O(2) or iNO, although better physiologic function may be obtained when iNO concentrations are constant and O(2) is reduced. This has important implications in the clinical management of critically ill newborns treated with O(2) and iNO for pulmonary disorders.

Animals↗
PubMed2002

Elevated generation of reactive oxygen/nitrogen species in hantavirus cardiopulmonary syndrome.

Hantavirus cardiopulmonary syndrome (HCPS) is a life-threatening respiratory disease characterized by profound pulmonary edema and myocardial depression. Most cases of HCPS in North America are caused by Sin Nombre virus (SNV), which is carried asymptomatically by deer mice (Peromyscus maniculatus). The underlying pathophysiology of HCPS is poorly understood. We hypothesized that pathogenic SNV infection results in increased generation of reactive oxygen/nitrogen species (RONS), which contribute to the morbidity and mortality of HCPS. Human disease following infection with SNV or Andes virus was associated with increased nitrotyrosine (NT) adduct formation in the lungs, heart, and plasma and increased expression of inducible nitric oxide synthase (iNOS) in the lungs compared to the results obtained for normal human volunteers. In contrast, NT formation was not increased in the lungs or cardiac tissue from SNV-infected deer mice, even at the time of peak viral antigen expression. In a murine (Mus musculus) model of HCPS (infection of NZB/BLNJ mice with lymphocytic choriomeningitis virus clone 13), HCPS-like disease was associated with elevated expression of iNOS in the lungs and NT formation in plasma, cardiac tissue, and the lungs. In this model, intraperitoneal injection of 1400W, a specific iNOS inhibitor, every 12 h during infection significantly improved survival without affecting intrapulmonary fluid accumulation or viral replication, suggesting that cardiac damage may instead be the cause of mortality. These data indicate that elevated production of RONS is a feature of pathogenic New World hantavirus infection and that pharmacologic blockade of iNOS activity may be of therapeutic benefit in HCPS cases, possibly by ameliorating the myocardial suppressant effects of RONS.

Adolescent↗
PubMed2002

Killing of Klebsiella pneumoniae by human alveolar macrophages.

We investigated putative mechanisms by which human surfactant protein A (SP-A) effects killing of Klebsiella pneumoniae by human alveolar macrophages (AMs) isolated from bronchoalveolar lavagates of patients with transplanted lungs. Coincubation of AMs with human SP-A (25 microg/ml) and Klebsiella resulted in a 68% decrease in total colony forming units by 120 min compared with AMs infected with Klebsiella in the absence of SP-A, and this SP-A-mediated effect was abolished by preincubation with N(G)-monomethyl-L-arginine. Incubation of transplant AMs with SP-A increased intracellular Ca(2+) concentration ([Ca(2+)](i)) by 70% and nitrite and nitrate (NO(x)) production by 45% (from 0.24 +/- 0.02 to 1.3 +/- 0.21 nmol small middle dot 10(6) AMs(-1).h(-1)). Preincubation with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester inhibited the increase in [Ca(2+)](i) and abrogated the SP-A-mediated Klebsiella phagocytosis and killing. In contrast, incubation of AMs from normal volunteers with SP-A decreased both [Ca(2+)](i) and NO(x) production and did not result in killing of Klebsiella. Significant killing of Klebsiella was also seen in a cell-free system by sustained production of peroxynitrite (>1 microM/min) at pH 5 but not at pH 7.4. These findings indicate that SP-A mediates pathogen killing by AMs from transplant lungs by stimulating phagocytosis and production of reactive oxygen-nitrogen intermediates.

Bronchoalveolar Lavage Fluid↗
PubMed2002

cAMP regulation of Cl(-) and HCO(-)(3) secretion across rat fetal distal lung epithelial cells.

We isolated and cultured fetal distal lung epithelial (FDLE) cells from 17- to 19-day rat fetuses and assayed for anion secretion in Ussing chambers. With symmetrical Ringer solutions, basal short-circuit currents (I(sc)) and transepithelial resistances were 7.9 +/- 0.5 microA/cm(2) and 1,018 +/- 73 Omega.cm(2), respectively (means +/- SE; n = 12). Apical amiloride (10 microM) inhibited basal I(sc) by approximately 50%. Subsequent addition of forskolin (10 microM) increased I(sc) from 3.9 +/- 0.63 microA/cm(2) to 7.51 +/- 0.2 microA/cm(2) (n = 12). Basolateral bumetanide (100 microM) decreased forskolin-stimulated I(sc) from 7.51 +/- 0.2 microA/cm(2) to 5.62 +/- 0.53, whereas basolateral 4,4'-dinitrostilbene-2,2'-disulfonate (5 mM), an inhibitor of HCO secretion, blocked the remaining I(sc). Forskolin addition evoked currents of similar fractional magnitudes in symmetrical Cl(-)- or HCO(-)(3)-free solutions; however, no response was seen using HCO(-)(3)- and Cl(-)-free solutions. The forskolin-stimulated I(sc) was inhibited by glibenclamide but not apical DIDS. Glibenclamide also blocked forskolin-induced I(sc) across monolayers having nystatin-permeablized basolateral membranes. Immunolocalization studies were consistent with the expression of cystic fibrosis transmembrane conductance regulator (CFTR) protein in FDLE cells. In aggregate, these findings indicate the presence of cAMP-activated Cl(-) and HCO(-)(3) secretion across rat FDLE cells mediated via CFTR.

Amiloride↗
PubMed2002

Alveolar macrophage activation after trauma-hemorrhage and sepsis is dependent on NF-kappaB and MAPK/ERK mechanisms.

The acute respiratory distress syndrome (ARDS) is a major cause of morbidity after injury. We hypothesized that alveolar macrophage (AMPhi) chemokine and cytokine release after hemorrhage and sepsis is regulated by NF-kappaB and MAPK. Adult male rats underwent soft tissue trauma and hemorrhagic shock (~90 min) followed by crystalloid resuscitation. Sepsis was induced by cecal ligation and puncture (CLP) 20 h after resuscitation. AMPhi were harvested, and TNF-alpha, IL-6, and macrophage inflammatory protein (MIP)-2 release and serum IL-6 and TNF-alpha levels were measured at 5 h after HCLP. Lung tissues were analyzed for activation of NF-kappaB, myeloperoxidase activity, and wet/dry weight ratio. In control animals, AMPhi were stimulated with LPS with or without inhibitors of NF-kappaB and MAPK. Serum TNF-alpha and IL-6 levels and spontaneous AMPhi TNF-alpha and MIP-2 release were elevated (P < 0.05) after HCLP, concomitantly with the development of lung edema and leukocyte activation. Activation of NF-kappaB increased in lungs from the hemorrhage and CLP group compared with shams. Inhibition of NF-kappaB or the upstream MAPK significantly decreased LPS-stimulated AMPhi activation. Because enhanced release of inflammatory mediators by AMPhi may contribute to ARDS after severe trauma, inhibition of intracellular signaling pathways represents a target to attenuate organ injury under those conditions.

Animals↗
PubMed2002

Invited review: biophysical properties of sodium channels in lung alveolar epithelial cells.

Amiloride-sensitive sodium channels in the lung play an important role in lung fluid balance. Particularly in the alveoli, sodium transport is closely regulated to maintain an appropriate fluid layer on the surface of the alveoli. Alveolar type II cells appear to play an important role in this sodium transport, with the role of alveolar type I cells being less clear. In alveolar type II cells, there are a variety of different amiloride-sensitive, sodium-permeable channels. This significant diversity appears to play a role in both normal lung physiology and in pathological states. In many epithelial tissues, amiloride-sensitive epithelial sodium channels (ENaC) are formed from three subunit proteins, designated alpha-, beta-, and gamma-ENaC. At least part of the diversity of sodium-permeable channels in lung arises from the assembling of different combinations of these subunits to form channels with different biophysical properties and different mechanisms for regulation. This leads to epithelial tissue in the lung, which has enormous flexibility to alter the magnitude and regulation of salt and water transport. In this review, we discuss the biophysical properties and occurrence of these various channels and some of the mechanisms for their regulation.

Animals↗
PubMed2002

Oxidant-antioxidant balance in acute lung injury.

ARDS is a disease process that is characterized by diffuse inflammation in the lung parenchyma. The involvement of inflammatory mediators in ARDS has been the subject of intense investigation, and oxidant-mediated tissue injury is likely to be important in the pathogenesis of ARDS. In response to various inflammatory stimuli, lung endothelial cells, alveolar cells, and airway epithelial cells, as well as activated alveolar macrophages, produce both nitric oxide and superoxide, which may react to form peroxynitrite, which can nitrate and oxidize key amino acids in various lung proteins, such as surfactant protein A, and inhibit their functions. The nitration and oxidation of a variety of crucial proteins present in the alveolar space have been shown to be associated with diminished function in vitro and also have been identified ex vivo in proteins sampled from patients with acute lung injury (ALI)/ARDS. Various enzymes and low-molecular-weight scavengers that are present in the lung tissue and alveolar lining fluid decreased the concentration of these toxic species. The purpose of this brief chapter is to review the results from various studies demonstrating increased levels of reactive oxygen-nitrogen intermediates in the alveolar spaces of patients with ALI/ARDS.

Antioxidants↗
PubMedDate not supplied

The role of nitric oxide in lung innate immunity: modulation by surfactant protein-A.

Surfactant protein A (SP-A) and alveolar macrophages are essential components of lung innate immunity. Alveolar macrophages phagocytose and kill pathogens by the production of reactive oxygen and nitrogen species. In particular, peroxynitrite, the reaction product of superoxide and nitric oxide, appears to have potent antimicrobial effects. SP-A stimulates alveolar macrophages to phagocytose and kill pathogens and is important in host defense. However, SP-A has diverse effects on both innate and adaptive immunity, and may stimulate or inhibit immune function. SP-A appears to mediate toxic or protective effects depending on the immune status of the lung. In contrast to mouse or rat cells, it has been difficult to demonstrate nitric oxide production by human macrophages. We have recently demonstrated that human macrophages produce nitric oxide and use it to kill Klebsiella pneumoniae. SP-A either stimulates or inhibits this process, depending on the activation state of the macrophage. Given its diverse effects on immune function, SP-A may prove to be an effective therapy for both infectious and inflammatory diseases of the lung.

Animals↗