Interleukin 1-stimulated prostacyclin synthesis in endothelium: lack of phospholipase C, phospholipase D, or protein kinase C involvement in early signal transduction

The cascade of transmembrane signaling events that follow the occupancy of the interleukin 1 receptor remain poorly defined. We examined potential postreceptor transduction systems involved in human recombinant interleukin 1-beta-stimulated prostacyclin synthesis in human umbilical vein endothelium. Challenge of human umbilical vein endothelium monolayers with recombinant interleukin 1-beta resulted in dose- and time-dependent tritiated arachidonate release and prostacyclin synthesis consistent with phospholipase A2 activation. Prostacyclin synthesis after interleukin 1-beta (10 ng/ml) was detected 4 hours after stimulation and peaked at 16 to 24 hours. To examine whether interleukin 1-beta produced early activation of a phosphoinositide-specific phospholipase C, human umbilical vein endothelium monolayers were labeled with tritiated-2-myoinositol and inositol polyphosphates recovered after interleukin 1-beta stimulation. In contrast to the potent agonist, alpha-thrombin, interleukin 1-beta failed to significantly increase inositol phosphate production when examined for up to 4 hours. The absence of a significant increase in the Cai++ secretagogue, IP3, was confirmed in human umbilical vein endothelium monolayers loaded with the Ca++ photoprotein probe aequorin. Basal aequorin luminescence was unaltered after interleukin 1-beta (0 to 2 hours), whereas both alpha-thrombin and Ca++ ionophore A23187 produced rapid rises in Cai++. The intracellular Ca++ antagonist BAPTA and the extracellular Ca++ chelator EGTA produced significant inhibition of interleukin 1-beta-stimulated prostacyclin generation at 4 to 8 hours, suggesting either an indirect inhibitory effect of these agents on phospholipase A2 activity or that an increase in Ca++ may be a late event in the transduction scheme after interleukin 1 stimulation. Interleukin 1-beta-stimulated protein kinase C, phospholipase D, and adenylyl cyclase activities (0 to 4 hours) were unchanged from controls. Despite the absence of increased plasma membrane protein kinase C activity up to 4 hours after interleukin 1, pretreatment of human umbilical vein endothelium monolayers with staurosporine or phorbol myristate acetate (18 hours) to reduce protein kinase C activities, significantly attenuated the interleukin 1-stimulated prostanoid responses at 16 hours but not at 4 hours. Furthermore, short (5 minute) pretreatment with phorbol myristate acetate dramatically augmented interleukin 1-mediated prostacyclin responses in synergistic fashion, suggesting that protein kinase C may modulate interleukin 1 signal transducing pathways. In summary, these studies suggest that interleukin 1-beta-mediated endothelial cell phospholipase A2 activity and prostacyclin synthesis occur via a novel transducing pathway that does not involve early activation of phospholipase C, phospholipase D, or adenylate cyclase.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular mechanisms of thrombin-induced human and bovine endothelial cell activation

Thrombin, the key regulatory protein of hemostasis, is a potent stimulus for endothelial cell activation, a process implicated in a variety of ischemic, thrombotic, and inflammatory vascular disorders. Activation of the thrombin receptor requires a novel mechanism of receptor proteolysis generating a tethered receptor ligand. Synthetic peptides whose sequences are identical to this newly exposed receptor NH2-terminus reproduce thrombin effects on human and bovine endothelial cell activation. Receptor cleavage by catalytically active alpha-thrombin is tightly coupled to a PI-PLC, with resultant generation of IP3 and DAG, increases in [Ca2+]i, and translocation of PKC (Fig. 3). Both the increase in [Ca2+]i and PKC activation are required for thrombin-stimulated PLA2 and PLD activity, PGI2 synthesis, and barrier dysfunction, the latter occurring as the result of Ca2+ and PKC effects on specific cytoskeletal protein elements and other contractile proteins (Fig. 3). Further investigations are ongoing to identify more clearly not only the precise biochemical intermediates involved in the endothelial cell response to thrombin but also the specific protein kinase systems involved in thrombin-mediated signal transduction in vascular endothelium.

Protein kinase C phosphorylates caldesmon77 and vimentin and enhances albumin permeability across cultured bovine pulmonary artery endothelial cell monolayers

Cytoskeletal protein (CSP) interactions are critical to the contractile response in muscle and non-muscle cells. Current concepts suggest that activation of the contractile apparatus occurs through selective phosphorylation by specific cellular kinase systems. Because the Ca(2+)-phospholipid-dependent protein kinase C (PKC) is involved in the regulation of a number of key endothelial cell responses, the hypothesis that PKC modulates endothelial cell contraction and monolayer permeability was tested. Phorbol myristate acetate (PMA), a direct PKC activator, and alpha-thrombin, a receptor-mediated agonist known to increase endothelial cell permeability, both induced rapid, dose-dependent activation and translocation of PKC in bovine pulmonary artery endothelial cells (BPAEC), as assessed by gamma-[32P]ATP phosphorylation of H1 histone in cellular fractions. This activation was temporally associated with evidence of agonist-mediated endothelial cell contraction as demonstrated by characteristic changes in cellular morphology. Agonist-induced activation of the contractile apparatus was associated with increases in BPAEC monolayer permeability to albumin (approximately 200% increase with 10(-6) MPMA, approximately 400% increase with 10(-8) M alpha-thrombin). To more closely examine the role of PKC in activation of the contractile apparatus, PKC-mediated phosphorylation of two specific CSPs, the actin- and calmodulin-binding protein, caldesmon77, and the intermediate filament protein, vimentin, was assessed. In vitro phosphorylation of both caldesmon and vimentin was demonstrated by addition of exogenous, purified BPAEC PKC to unstimulated BPAEC homogenates, to purified bovine platelet caldesmon77, or to purified smooth muscle caldesmon150. Caldesmon77 and vimentin phosphorylation were observed in intact [32P]-labeled BPAEC monolayers stimulated with either PMA or alpha-thrombin, as detected by immunoprecipitation. In addition, BPAEC pretreatment with the PKC inhibitor, staurosporine, prevented alpha-thrombin- and PMA-induced phosphorylation of both cytoskeletal proteins, attenuated morphologic evidence of contraction, and abolished agonist-induced barrier dysfunction. These results demonstrate that agonist-stimulated PKC activity results in cytoskeletal protein phosphorylation in BPAEC monolayer, an event which occurs in concert with agonist-mediated endothelial cell contraction and resultant barrier dysfunction.

Structure of 2,5:3,4-dianhydro-D-altritol

3,6-Dioxabicyclo[3.1.0]hexane-2,4-dimethanol, C6H10O4, M(r) = 146.1, orthorhombic, P2(1)2(1)2(1), a = 7.6209 (2), b = 9.1292 (3), c = 9.6135 (5) A, V = 668.8 (1) A3, Z = 4, Dx = 1.451 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.15 cm-1, F(000) = 312, T = 298 K, R = 0.029 for 1280 observations with I greater than 3 sigma(I) (of 1695 unique data). The tetrahydrofuran ring has the envelope conformation, OE, with P of 94.3 degrees and tau m = 24.0 degrees. C atoms deviate from their best plane by +/- 0.0006 (1) to 0.010 (1) A, and the O atom lies 0.331 (1) A from that plane. The epoxide O atom is syn to the tetrahydrofuran O atom. Each hydroxy group is involved in intermolecular hydrogen bonding both as donor and acceptor. The two hydrogen bonds have O...O distances of 2.743 (1) and 2.729 (1) A, and angles about H of 166.3 (12) and 172 (2) degrees, respectively.

Inhibition of acetylcholinesterase by hemicholiniums, conformationally constrained choline analogues. Evaluation of aryl and alkyl substituents. Comparisons with choline and (3-hydroxyphenyl)trimethylammonium

2-Substituted-2-hydroxy-4,4-dimethylmorpholiniums (hemicholiniums) inhibit acetylcholinesterase (EC 3.1.1.7)-catalyzed hydrolysis of acetylthiocholine (ATCh). The 4-substituted arenes [NH2, NHC(O)CH3, Cl, CN, and NO2] have values of inhibition constants (Ki) that range from 220 to 3690 microM, which correlate with Hammett sigma, rho approximately 0.8. The alkyl compounds, hydrogen, methyl, tert-butyl, and trifluoromethyl, have values of Ki of 550, 560, 1200, and 1200 microM, respectively. These values compare favorably with Ki = 960 microM for choline. The conformation of AChE-bound choline must be gauche to support our suggestion that hemicholiniums are conformationally constrained analogues of choline. (3-Hydroxyphenyl)trimethylammonium (5) inhibits most strongly, Ki = 0.21 microM, of the compounds examined in this study. The solvent isotope effect (H2OKi/D2OKi = 0.83 +/- 0.04) suggests that inhibition by 5 involves hydrogen bonding. The binding by AChE of the hemicholiniums of various sizes and the strong binding of 5 support an earlier proposal [Schowen, K. B., Smissman, E. E., and Stephen, W. F., Jr. (1975) J. Med. Chem. 18, 292-300] that the active site of AChE has ample space for rotation about the C-C bond in choline. Compound 5, which has one more carbon between the hydroxy and trimethylammonium than does choline, inhibits much more potently than either choline or the hemicholiniums. Compound 5 provides a correct spacer to span the trimethylammonium recognition site and the esteratic site of AChE. This aromatic spacer interacts favorably with the hydrophobic active site, and the phenolic hydroxyl probably hydrogen bonds to the histidine in the esteratic site. Choline in any conformation and the hemicholiniums are too short to make a strong hydrogen bond.

Thrombin stimulation of human endothelial cell phospholipase D activity. Regulation by phospholipase C, protein kinase C, and cyclic adenosine 3'5'-monophosphate

The activation of membrane-bound phospholipase D (PLD) resulting in the generation of phosphatidic acid (PA) is increasingly recognized as an integral event in the initiation of a variety of cellular responses. We explored whether alpha-thrombin is a physiologic agonist for PLD activation in human umbilical vein endothelial cells (HUVEC). HUVEC monolayers were labeled with [32Pi] and PLD activity determined by formation of the PLD metabolite [32P] phosphatidylethanol (PEt) in the presence of 5 g/L ethanol by thin-layer chromatography. alpha-Thrombin rapidly (1 minute) increased PA and PEt formation in a dose-dependent manner (10(-6) to 10(-10)) with maximal PLD stimulation achieved with 10 nmol/L alpha-thrombin producing a threefold to fourfold increase in PA and a sixfold to eightfold increase in PEt over controls at 15 minutes. Esterolytically active zeta-thrombin (10 nmol/L) and gamma-thrombin (1 mumol/L), but not inactive DIP-alpha-thrombin (1 mumol/L) also increased PLD activity. The role of Ca2+ flux in human endothelial cell PLD activation was investigated and PEt formation was significantly enhanced by Ca2+ ionophores A23187 and ionomycin (1 mumol/L, three-fold to fourfold increase in PEt). Alpha-Thrombin-stimulated PEt formation was abolished (greater than 90% inhibition) with chelation of intracellular calcium (Ca2+i) by pretreatment with BAPTA-AM (25 mumol/L, 30 minutes) but only mildly attenuated (30% inhibition) by removal of extracellular calcium (Ca2+E) with EGTA (5 mmol/L). The protein kinase C (PKC) inhibitor staurosporine reduced alpha-thrombin-induced PEt formation in a dose-dependent manner (10 mumol/L, 78% inhibition) and PKC downregulation with chronic PMA treatment (18 hours) also resulted in marked inhibition of alpha-thrombin-induced PEt formation. Neither pertussis nor botulinum C bacterial toxins significantly altered alpha-thrombin-induced PLD responses. In contrast, similar pretreatment with cholera toxin (1 microgram/mL, 60 minutes) consistently augmented alpha-thrombin-stimulated PLD activity by 50% to 90%. Comparable results were observed with agents which increased cAMP such as forskolin, 8-bromo cAMP, or dibutyryl cAMP and cholera toxin augmentation was abolished by 2-dideoxyadenosine, a competitive inhibitor of adenylyl cyclase activity. These studies demonstrate that alpha-thrombin is a potent stimulus for human PLD-mediated PA formation and that cyclic adenosine nucleotides modulate agonist-induced cellular PLD activity. In this model of PLD activation, alpha-thrombin receptor occupancy leads to the breakdown of phosphatidylinositol 4,5-bisphosphate catalyzed by phospholipase C producing the Ca2+ secretagogue IP3 and DAG.(ABSTRACT TRUNCATED AT 400 WORDS)

Interleukin 1 alpha mediated inhibition of myogenic terminal differentiation: increased sensitivity of Ha-ras transformed cultures

The commitment of myogenically determined cells to terminal differentiation can be modulated by a variety of agents, including growth factors and activated oncogenes. We have examined the effect of interleukin 1 alpha (IL-1 alpha) on the terminal differentiation of a normal myogenically determined cell line and two myogenically determined, differentiation competent cell lines which contain either one or six copies of the activated c-Ha-ras oncogene. Treatment of all cell lines with IL-1 alpha decreased but did not totally inhibit terminal myogenic differentiation. Over the range of IL-1 alpha concentrations assayed (1-40 ng/ml), the c-Ha-ras transformed cell lines demonstrated a significantly greater sensitivity to the inhibitory effects of IL-1 alpha. The inhibition of differentiation was not the result of enhanced proliferation. Interestingly, transformation with activated c-Ha-ras resulted in a decrease in IL-1 alpha receptor number and affinity. The enhanced IL-1 alpha responsiveness of the ras transformants was not the result of increased proliferation or changes in either ras gene expression or protein kinase C activity. IL-1 alpha treatment decreased the steady-state levels of both MyoD1 and myogenin transcripts in the c-Ha-ras transformed but not the normal myogenic cell line. Further studies are required to determine the mechanism(s) responsible for the increased sensitivity of the c-Ha-ras transformed cultures to the inhibitory effects of IL-1 alpha.

Phosphorylation by casein kinase II alters the biological activity of calmodulin

Calmodulin is the major intracellular Ca(2+)-binding protein, providing Ca(2+)-dependent regulation of numerous intracellular enzymes. The phosphorylation of calmodulin may provide an additional mechanism for modulating its function as a signal transducer. Phosphocalmodulin has been identified in tissues and cells, and calmodulin is phosphorylated both in vitro and in intact cells by various enzymes. Phosphorylation of calmodulin on serine/threonine residues by casein kinase II decreases its ability to activate both myosin-light-chain kinase and cyclic nucleotide phosphodiesterase. For myosin-light-chain kinase the primary effect is an inhibition of the Vmax. of the reaction, with no apparent change in the concentration at which half-maximal velocity is attained (K0.5) for either Ca2+ or calmodulin. In contrast, for phosphodiesterase, phosphorylation of calmodulin significantly increases the K0.5 for calmodulin without noticeably altering the Vmax. or the K0.5 for Ca2+. The higher the stoichiometry of phosphorylation of calmodulin, the greater the inhibition of calmodulin-stimulated activity for both enzymes. Therefore the phosphorylation of calmodulin by casein kinase II appears to provide a Ca(2+)-independent mechanism whereby calmodulin regulates at least two important target enzymes, myosin-light-chain kinase and cyclic nucleotide phosphodiesterase.

Evans blue dye as a marker of albumin clearance in cultured endothelial monolayer and isolated lung

Determination of protein transfer across the endothelial barrier or the entire alveolar capillary membrane is critical for investigation of mechanisms leading to pulmonary edema. The purpose of this study was to evaluate Evans blue dye for determination of protein clearance across cultured bovine pulmonary artery endothelial cell monolayers and as a quantitative marker for albumin leakage to the air spaces in isolated perfused rat lungs. Evans blue dye bound tightly to albumin (EBA) as determined by lack of transfer through dialysis membranes and specific elution with albumin from a molecular exclusion column. EBA was equivalent to 125I-labeled albumin for calculation of albumin clearance rates (Calb) across intact and challenged monolayers [Calb (+ vehicle) = 0.12 microliters/min; Calb (+10 nM alpha-thrombin) = 0.47 microliters/min; Calb (+5 mg/ml trypsin) = 1.29 microliters/min]. Transfer of EBA was linear with time in both the endothelial cell monolayer model and the perfused lung. EBA was a sensitive marker for early edema in the perfused lung (before detectable weight gain) as well as for severe edema in the oxidant-injured lung (marked EBA accumulation in lavage fluid) and was a more specific marker for protein transfer than lavage fluid protein. EBA transfer is a convenient, reproducible, and accurate means to assess alterations in vascular permeability.

Evans blue dye as a marker of albumin clearance in cultured endothelial monolayer and isolated lung

Determination of protein transfer across the endothelial barrier or the entire alveolar capillary membrane is critical for investigation of mechanisms leading to pulmonary edema. The purpose of this study was to evaluate Evans blue dye for determination of protein clearance across cultured bovine pulmonary artery endothelial cell monolayers and as a quantitative marker for albumin leakage to the air spaces in isolated perfused rat lungs. Evans blue dye bound tightly to albumin (EBA) as determined by lack of transfer through dialysis membranes and specific elution with albumin from a molecular exclusion column. EBA was equivalent to 125I-labeled albumin for calculation of albumin clearance rates (Calb) across intact and challenged monolayers [Calb (+ vehicle) = 0.12 microliters/min; Calb (+10 nM alpha-thrombin) = 0.47 microliters/min; Calb (+5 mg/ml trypsin) = 1.29 microliters/min]. Transfer of EBA was linear with time in both the endothelial cell monolayer model and the perfused lung. EBA was a sensitive marker for early edema in the perfused lung (before detectable weight gain) as well as for severe edema in the oxidant-injured lung (marked EBA accumulation in lavage fluid) and was a more specific marker for protein transfer than lavage fluid protein. EBA transfer is a convenient, reproducible, and accurate means to assess alterations in vascular permeability.

Role of protein kinase C in the regulation of prostaglandin synthesis in human endothelium

The present study specifically addresses the role of protein kinase C (PKC) activation in human endothelial cell Ca2+ mobilization, a response that is functionally coupled to the production of the potent arachidonate (AA) metabolite, prostacyclin (PGI2). Phorbol 12-myristate 13-acetate (PMA), alpha-thrombin, and sodium fluoride (NaF), a direct G-protein activator, produced a rapid and time-dependent translocation of PKC from the cytosol to the membrane. Activation of PKC by brief pretreatment of human umbilical vein endothelial cell (HUVEC) monolayers with PMA resulted in the inhibition of NaF-induced inositol phosphate increases and attenuation of both alpha-thrombin- and NaF-activated increases in intracellular Ca2+ (Ca2+i). Ca2+ mobilization induced by ionophore A23187 was not affected by PKC preactivation, suggesting PKC-dependent negative feedback inhibition of phosphatidylinositol (PI)-specific phospholipase C (PLC). Agonist-stimulated AA release and PGI2 synthesis in PMA-pretreated cultured human endothelial cells, however, was potentiated, and the enhanced PGI2 synthesis produced by A23187, NaF, and alpha-thrombin was dependent upon the dose of PMA. Treatment of HUVEC monolayers with an intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N'N'-tetraacetic acid-acetoxymethylester (BAPTA-AM), dramatically reduced alpha-thrombin-, NaF-, and A23187-induced PGI2 synthesis, demonstrating the importance of Ca2+i availability in PGI2 synthesis. BAPTA pretreatment did not inhibit PMA-induced PKC activation, and BAPTA-mediated inhibition of agonist-stimulated PGI2 synthesis was partially attenuated by prior PMA pretreatment. Staurosporine, a potent PKC inhibitor, at concentrations that inhibited PKC-induced phosphorylation of histone-1, augmented both alpha-thrombin- and NaF-induced production of inositol phosphates but markedly inhibited alpha-thrombin-, NaF-, and A23187-induced PGI2 synthesis. The downregulation of PKC activity by prolonged PMA treatment (18 h) produced similar inhibition of PGI2 synthesis by these agonists (approximately 50% inhibition). These studies indicate that the integrated phospholipase A2 and PLC activities are under complex regulation by factors that include both PKC activation and [Ca2+i]. PKC exerts dual effects on prostaglandin synthesis via negative regulation of Gp-coupled PI-specific PLC and positive feedback regulation of AA release and PGI2 synthesis. PKC is thus a critical determinant in the regulation of human endothelial cell prostaglandin synthesis by both receptor-mediated and G-protein-dependent cellular activation.

Hyperoxic exposure in humans. Effects of 50 percent oxygen on alveolar macrophage leukotriene B4 synthesis

The pathogenesis of oxygen toxicity remains unknown but may involve leukocyte mediated injury. The effects of hyperoxia on several lower respiratory tract parameters were examined in bronchoalveolar lavage fluid of normal nonsmoking subjects who inhaled a fractional inspired oxygen concentration of 50 percent (mean exposure: 44 h). Evidence that 50 percent O2 produced oxidative stress in the lung included recovery of fluorescent products of lipid peroxidation and partial oxidation of alpha 1-antitrypsin in BAL fluid obtained after O2 exposure. To examine whether alveolar macrophage-derived leukotriene B4 may be generated in response to 50 percent O2, AM were isolated from O2-exposed subjects and compared with AM recovered from subjects breathing room air. Leukotriene B4 levels were elevated in supernatants from both unstimulated and arachidonic acid-stimulated AM obtained from hyperoxia-exposed subjects. In hyperoxia-exposed individuals, LTB4 levels were also elevated in extracted BAL fluid. The percentage of BAL neutrophils was also significantly increased after O2 exposure (2.8 +/- 0.6 vs 1.2 +/- 0.4 percent, p = 0.05). We conclude that an FIO2 of 50 percent inhaled for 44 h is associated with enhanced oxidative stress, stimulation of AM to release LTB4, and a small but significantly increased percentage of neutrophils recovered in BAL fluid.

Gp-regulated phosphoinositide hydrolysis in turkey and human erythrocytes exposed to fluoride ion: relationship to calcium influx

Previous studies have demonstrated that although both mammalian and avian erythrocytes express an inducible inositol bisphosphate-specific phospholipase C, only the latter possess the guanine nucleotide-binding protein (Gp) that regulates this activity. In confirmation of previous reports, turkey erythrocyte plasma membranes responded to guanosine 5'-0-(3-thio)triphosphate (GTP-gamma-S) and fluoroaluminates with hydrolysis of phosphoinositides, release of inositol phosphates, and generation of diacylglycerol, whereas human erythrocyte plasma membranes exhibited no such changes when incubated with known activators of guanine nucleotide regulatory proteins. We next contrasted responses of intact turkey and human erythrocytes to fluoroaluminates to develop a model to investigate the cellular effects of Gp activation. When turkey erythrocytes were exposed to fluoroaluminates, cellular levels of diacylglycerol and phosphatidic acid rapidly increased as phosphoinositides were hydrolyzed. The alterations in the lipid composition of turkey erythrocytes effected by fluoroaluminates were remarkable; phosphatidic acid levels increased over 30-fold, whereas levels of polyphosphoinositides were decreased to less than 10% of those present before stimulation. In contrast, fluoroaluminates caused only minor alterations in the diacylglycerol and phospholipid content of intact human erythrocytes. To define the role of inositol-specific phospholipase C activation in the transmembrane conveyance of extracellular Ca++, we compared the influx of extracellular Ca++ in human and turkey erythrocytes exposed to fluoroaluminates. Fluoroaluminates initiated a sustained influx of extracellular 45Ca++ into turkey, but not human, erythrocytes. These results provide strong support for the hypothesis that Gp activation results in an influx of calcium into stimulated cells. Moreover, the data demonstrate that comparison of responses of human and turkey erythrocytes to fluoroaluminates provides a well-defined method for investigating the mechanisms and consequences of Gp activation in intact cells.

The role of protein kinase C in alpha-thrombin-mediated endothelial cell activation

Thrombin, the key regulatory protein of hemostasis, has been implicated in a variety of important endothelial cell processes closely linked to endothelial signal transduction mechanisms. An initial event, following receptor binding by catalytically active alpha-thrombin, appears to be the activation of a G-protein-coupled, PI-specific PLC, with resultant generation of IP3 and DAG, with increases in [Ca2+]i, and activation and translocation of PKC (Fig. 9). PKC activation results in down-regulation of PLC, as demonstrated by inhibition of agonist-induced increases in [Ca2+]i, whereas PLA2 activity is up-regulated, with a resultant increase in endothelial PGI2 synthesis. Recently, we have demonstrated that activity of membrane-bound, endothelial PLD, is also up-regulated by PKC activation. In addition to its modulatory role in endothelial cell phospholipase activities, PKC activation appears to play a critical role in thrombin-mediated endothelial barrier dysfunction, likely via specific cytoskeletal protein phosphorylation. A temporal relationship between alpha-thrombin-mediated signal transduction and specific cellular responses, such as PGI2 synthesis and barrier dysfunction, can be established (Fig. 2). Further investigations are ongoing to identify more clearly the precise biochemical intermediates involved in the endothelial cell response to thrombin, as well as the role of differential phosphorylation by various protein kinase systems in thrombin-mediated signal transduction in vascular endothelium.

Fluoride mobilizes intracellular calcium and promotes Ca2+ influx in rat proximal tubules

In the renal proximal tubule, external Ca2+ ([Ca2+]o) is required for parathyroid hormone to elevate cytosolic Ca2+ ([Ca2+]i). However, other hormones increase [Ca2+]i in the absence of [Ca2+]o. These differences may arise from a diversity of signal transduction pathways acting on external and internal Ca2+ pools. However, Ca2+ influx may be necessary to expedite and maintain the rise of [Ca2+]i for a period after the initial surge. In this study, F- was used to probe the roles of intracellular Ca2+ mobilization, Ca2+ influx, and phosphoinositide (PI) hydrolysis on the surge of [Ca2+]i in rat proximal tubules. In the presence of external Ca2+; 1-20 mM F- evoked incremental rises of [Ca2+]i in tubules loaded with aequorin. Whereas 10 mM F- increased [Ca2+]i in the absence of [Ca2+]o, the time constant for the [Ca2+]i surge was increased. These findings are consistent with a role of Ca2+ influx on the effect of F- on [Ca2+]i. Indeed, 10 mM F- also enhanced the uptake of 45Ca2+, and promoted Ca2+ influx in aequorin- and fura-2-loaded, Ca(2+)-deprived tubules. In tubules, F- also activated PI hydrolysis with a time course that paralleled Ca2+ mobilization. The effect of F- on [Ca2+]i was not altered when the 39-kDa pertussis toxin substrate was inactivated with the toxin. This G protein was most likely Gi, because prostaglandin E2, an activator of Gi in tubules, dissociated the pertussis toxin-sensitive protein. The results support the notion that activation of a signal-transduction complex, the F- substrate, causes Ca2+ influx, mobilizes internal Ca2+, and activates PI hydrolysis in rat proximal tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Sodium fluoride induces phosphoinositide hydrolysis, Ca2+ mobilization, and prostacyclin synthesis in cultured human endothelium: further evidence for regulation by a pertussis toxin-insensitive guanine nucleotide-binding protein

The role of guanine nucleotide-binding proteins in the induction of prostacyclin synthesis by stimulated endothelial cells is incompletely understood. We report that sodium fluoride (NaF), a potent activator of cellular guanine nucleotide-binding proteins, affected time- and concentration-dependent generation of prostacyclin (PGI2) by cultured human umbilical vein endothelial cells without evidence of cellular toxicity detected by 51Cr or lactate dehydrogenase release. PGI2 synthesis by NaF-stimulated endothelial cells was associated with increases in arachidonate release, phosphoinositide hydrolysis, generation of inositol phosphates, and accumulation of diacylglycerol. These responses to NaF, as well as alpha-thrombin-mediated responses, were not dependent upon the availability of extracellular free Ca2+ but were associated with the mobilization of stored intracellular Ca2+ detected by the luminescence of the photoprotein aequorin. Neither PGI2 synthesis nor Ca2+ responses following alpha-thrombin or NaF stimulation were inhibited by pretreatment of cells with the islet activating protein from Bordetella pertussis but were significantly attenuated by the G protein inhibitor GDP beta S in permeabilized cells. Our results are compatible with a model wherein NaF directly activates a phosphoinositidase-linked guanine nucleotide regulatory protein, Gp, in human umbilical vein endothelial cell monolayers. This activation results in phosphoinositide hydrolysis, Ca2+ mobilization, arachidonate release, and subsequent functional activation, assessed by PGI2 release. Biologically relevant agonists such as alpha-thrombin may exert their influence on arachidonate metabolism, in part, by promoting receptor-dependent activation of this G protein.

Diacylglycerol generation in fluoride-treated neutrophils: involvement of phospholipase D

Neutrophils exposed to fluoride ion (F-) respond with a delayed and sustained burst of superoxide anion release that is both preceded by and dependent on the influx of Ca2+ from the extracellular medium. The results of this study demonstrate a similarly delayed and sustained generation of 1,2-diglyceride in F(-)-treated neutrophils, over 90% of which was 1,2-diacylglycerol. Diacylglycerol generation was not dependent on the presence of extracellular Ca2+. Conversely, in contrast to results obtained with other agonists, removal of extracellular Ca2+ markedly potentiated synthesis of diacylglycerol in F(-)-treated neutrophils. This effect was accompanied by a corresponding decrease in the recovery of phosphatidic acid. In either the presence or absence of extracellular Ca2+, phosphatidic acid accumulated before diacylglycerol in F(-)-treated cells, suggesting the latter was derived from the former. Consistent with this hypothesis, the phosphatidic acid phosphohydrolase inhibitor, propranolol, suppressed generation of diacylglycerol as it potentiated the accumulation of phosphatidic acid in F(-)-treated neutrophils. This effect was observed both in the presence and absence of extracellular Ca2+. Moreover, high levels of propranolol (160 mumol/L) effected complete inhibition of diacylglycerol generation in F(-)-treated neutrophils with a corresponding increase in phosphatidic acid generation. Phosphatidylethanol accumulated in neutrophils stimulated with F- in the presence of ethanol. The extent of phosphatidylethanol accumulation at all time points after addition of F- corresponded to decreased levels of both phosphatidic acid and diacylglycerol, indicating that phosphatidylethanol was derived from the phospholipase D-catalysed transphosphatidylation reaction. The results indicate that F- activates a Ca(2+)-independent phospholipase D, which appears to be the major, if not sole, catalyst for both phosphatidic acid and diacylglycerol generation in F(-)-treated neutrophils. Ca2+, mobilized as a result of F- stimulation and possibly as a consequence of phospholipase D activation, exerts a profound effect on cellular second messenger levels by modulating the conversion of phosphatidic acid to diacylglycerol.

The usefulness of bronchoalveolar lavage in identifying past occupational exposure to asbestos: a light and electron microscopy study

Fiberoptic bronchoscopy has permitted the development of lavage procedures for the collection of lung washes. In certain disease states this material may contain large numbers of phagocytic cells (macrophages and neutrophils). Since these phagocytes are the predominant "dust scavenger cells" in the lung, the assessment of their particulate burden as well as that of the overall lavage material has been suggested as a potentially important diagnostic tool. The studies to date have shown that the presence of ferruginous bodies is an indication of past occupational exposure. In the present study, a digestion procedure was carried out on bronchoalveolar lavage material collected from individuals who were occupationally exposed to asbestos and from samples obtained from the general population. The parameters used for distinguishing the source of these samples included both light microscopy assessment of the filters for the presence of ferruginous bodies and electron microscopic screening for the presence of uncoated fibers.

Reduced diffusing capacity as an isolated finding in asbestos- and silica-exposed workers

From a cohort of 286 patients referred to an Occupational Medicine Clinic because of exposure to asbestos and/or silica, we identified 53 patients with a reduced diffusing capacity (Dco) (less than 75 percent predicted) as their only abnormality. Specifically, their clinical evaluation, chest roentgenograms, and remaining pulmonary function test results were all normal. These patients were divided into non-smokers (n = 13) and smokers (n = 40). The significance of the isolated reduction in diffusing capacity in these patients (n = 53) was explored with graded exercise testing (n = 19) and bronchoalveolar lavage (BAL) (n = 50). The results obtained from the patients with reduced diffusion were compared with those obtained from comparable smoking (n = 35) and nonsmoking patients (n = 37) in the original cohort who had normal chest roentgenograms and normal results of pulmonary function studies, including normal Dco values (greater than or equal to 75 percent of predicted value). Patients with low diffusion demonstrated a tendency for elevated alveolar to arterial O2 differences both at rest and during exercise, and a significant reduction in exercise capacity (VO2 max) was observed in the smoking patients with reduced diffusion when compared with their smoking counterparts with normal diffusion. All other exercise testing indexes were normal in the study groups and there was no correlation between the percent predicted Dco value and any of the exercise variables. In contrast, BAL revealed significant differences between patient groups. Both the smoking and nonsmoking patient groups with low Dco values had greater numbers of total BAL cells, alveolar macrophages, neutrophils, lymphocytes, and eosinophils in their BAL fluid than did their comparable controls with normal diffusion values. These differences were statistically significant (p less than .05) for total BAL cells and total macrophages in the nonsmoking patients and for total BAL cells, total macrophages, and total lymphocytes in the smoking patients expressed as either the total cell number per BAL or total cells per milliliter of BAL. In contrast to the observed exercise testing results, there was significant and inverse correlation between Dco values and each BAL cell type for all four groups combined as well as nonsmokers alone. The Dco values from smokers were significantly and inversely correlated with total BAL cells and total macrophages. These results suggest that the finding of a reduced Dco may be related to an active inflammatory process in the lung caused by occupational dust exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

High-performance liquid chromatographic analysis of radiolabeled inositol phosphates

Separation of inositol phosphates by low-pressure anion-exchange chromatography yields unsatisfactory results, while previously described anion-exchange HPLC methods require such extensive processing times that they preclude efficient sample analysis. Using a low-capacity Vydac nucleotide anion-exchange column, we have developed a method which allows complete separation of myo-inositol, inositol 1-phosphate, inositol 1,4-bisphosphate, inositol 1,4,5-trisphosphate, and inositol 1,3,4,5-tetrakisphosphate in approximately 10 min followed by a 5-min column regeneration time. This method provided exceptional reproducibility and quantitative recovery of each inositol phosphate. One column was used for over 300 separations with no loss in performance or alteration in elution pattern. A modified procedure with a 14-min gradient was developed to separate the 1,3,4- and 1,4,5-isomers of inositol trisphosphate. These separation procedures were used to characterize the kinetics of degradation of inositol phosphates by lysates of erythrocytes and neutrophils. We conclude that these procedures are applicable for rapid and quantitative analysis of radiolabeled inositol phosphates in cellular extracts.

Asbestos exposure results in increased lung procoagulant activity in vivo and in vitro

Enhanced fibrin deposition is a common histologic finding in fibrotic lung disorders including asbestosis and may be an important mechanism by which fibroblast proliferation is modulated. Asbestos-induced activation of lung interstitial cells may result in enhanced expression of procoagulant activity which contributes to the inflammatory response resulting in subsequent fibrin deposition. The current study examines procoagulant activity in bronchoalveolar lavage fluid from patients with clinically diagnosed asbestosis, patients with asbestos exposure without asbestosis, and normal, control subjects. Results indicated that asbestos exposure resulted in increased lung procoagulant expression in vivo, and furthermore, suggested that both endothelial cells and alveolar macrophages represented lung parenchymal cells which may contribute to this activity. This imbalance in coagulation homeostasis may be important in the regulation of fibrotic responses observed in asbestosis.

Decreased thrombin affinity of cell-surface thrombomodulin following treatment of cultured endothelial cells with beta-D-xyloside

Thrombomodulin, an endothelial cell-surface anticoagulant, has been postulated to contain a glycosaminoglycan. Thrombomodulin function was therefore studied in endothelial cells treated with beta-D-xyloside, an inhibitor of glycosaminoglycan attachment to proteoglycan core proteins. Beta-D-xyloside caused a reproducible 3 to 5-fold increase in the Km of thrombomodulin for thrombin and a 20-30% decrease in the rate of protein C activation by the thrombin-thrombomodulin complex. These results support a role for glycosaminoglycans in thrombomodulin function and suggest that beta-D-xylosides can be used to investigate both the anticoagulant mechanisms and the biosynthesis of cell-surface thrombomodulin.

Treating urinary incontinence in a head-injured adult

The purpose of this study was to determine the effects of four behavioural procedures in helping a head-injured adult to control diurnal and nocturnal enuresis. A multiple baseline, single subject research design was utilized to test the effectiveness of those procedures. Data were collected for a period of seven months, including four months of baseline and intervention, and three months of follow-up. Results showed that the frequency of urinary incidents was reduced to zero at the end of the treatment and follow-up periods. Implications of the research data for future studies about urinary incontinence in head-injured patients are discussed.

Thrombin-induced prostacyclin biosynthesis in human endothelium: role of guanine nucleotide regulatory proteins in stimulus/coupling responses

The regulation of prostacyclin (PGI2) synthesis by cultured human umbilical vein endothelium (HUVEC) was investigated. HUVEC monolayer generation of PGI2 was monitored by RIA of 6-keto PGF1 alpha and dose-dependent increases observed with human alpha- and gamma-thrombins, histamine, or arachidonate. Alpha thrombin (10 nM) produced levels of 6-keto PGF1 alpha approximating responses with 1 microM gamma-thrombin, 5 microM arachidonate, or 10 microM histamine. Diisopropyl phosphorofluoridate-inactivated alpha-thrombin did not stimulate PGI2 release, demonstrating that catalytic activity was required for thrombin-stimulated PGI2 release. Sodium fluoride (NaF), at concentrations known to activate guanine nucleotide regulatory proteins (G proteins), directly stimulated HUVEC PGI2 synthesis in a dose-dependent and time-dependent manner (20 mM NaF, 4.4 +/- 0.5-fold increase at 10 min, 11.9 +/- 1.5-fold increase at 30 min). Neither alpha-thrombin nor NaF-stimulated PGI2 release was dependent upon the availability of extracellular Ca++). The hypothesis that G proteins are involved in agonist-stimulated PGI2 synthesis was further supported by studies using digitonin-permeabilized HUVEC monolayers challenged with another G protein activator, guanosine 5'-0-3-thiotrisphosphate (GTP gamma S), which effected significant dose-dependent increases in PGI2 synthesis compared with control levels of 6-keto PGF1 alpha. In contrast, the G-protein inhibitor GDP beta S, (guanosine 5'-0-2-thiodiphosphate), attenuated alpha-thrombin-mediated prostaglandin generation. Treatment of HUVEC monolayers with pertussis toxin (1 microgram/ml) did not inhibit the PGI2 synthesis stimulated by either alpha-thrombin, NaF, or histamine but catalyzed the ADP ribosylation of a 40 kDa membrane protein which cross-reacted with antisera against a synthetic peptide corresponding to an amino acid sequence common to the alpha-subunit of other G-proteins. Preincubation of HUVEC microsomal membranes with alpha-thrombin diminished pertussis toxin-catalyzed ADP ribosylation in a time-dependent manner. These data suggest that thrombin stimulation of PGI2 synthesis by HUVEC monolayers requires the catalytically functional enzyme and further suggests that the thrombin-occupied receptor is coupled to phospholipase activities by a pertussis toxin-insensitive guanine nucleotide regulatory protein in human endothelial cell membranes.

Inosine monophosphate dehydrogenase inhibitors. Probes for investigations of the functions of guanine nucleotide binding proteins in intact cells

Taken together, the above reports indicate that the IMP dehydrogenase inhibitors are valuable probes for investigation of the biological functions of guanine nucleotides in intact cells. While these agents have minor effects on levels of other nucleotides and enzymes, non-specific effects can be monitored by addition of guanine or guanosine to provide substrates for the salvage pathway of guanine nucleotide synthesis. The most important question yet to be resolved in employing these agents is why incomplete depletion of intracellular guanine nucleotides results in such dramatic effects on G-protein function. Since the level of GTP in resting cells is approximately 0.5 mM, even a 90% reduction in GTP levels should leave enough nucleotide to adequately activate most known G-proteins, as the latter display high binding affinities for guanine nucleotides in cell free systems. Several explanations have been proposed to account for this disparity. Much of the intracellular guanine nucleotide may be bound or compartmentalized and therefore unable to interact with certain G-proteins. Possibly, G-proteins in the intracellular environment possess a much lower affinity for GTP that they do in cell free system. It may be to the cells' advantage that relatively minor fluctuations in levels of GTP result in pronounced alterations in the biological function of G-proteins as this effect may provide a physiologically important mechanism for the regulation of G-proteins in vivo. Further studies are necessary to clarify the mechanisms involved in the regulation of the biological function of G-proteins and oncogene products by guanine nucleotides in intact cells.

Ofloxacin in community-acquired lower respiratory infections. A comparison with amoxicillin or erythromycin

Ninety-one patients with community-acquired lower respiratory infections were treated orally in a comparative 10-day trial of ofloxacin versus amoxicillin or erythromycin. Approximately one-half of the patients had no major underlying disease and the other half had some form of chronic lung disease. Pneumonia was present in 31 percent of the patients and the remainder had purulent bronchitis. Bacterial pathogens were recovered from 60 percent of the patients, with Haemophilus influenzae (33 isolates) and Streptococcus pneumoniae (16 isolates) being the most common. Ofloxacin was found to be a safe, well-tolerated therapeutic agent, which was as effective clinically as amoxicillin or erythromycin and with an advantage of less frequent administration. Ofloxacin was more effective than amoxicillin (90 percent versus 75 percent; p = 0.05) in elimination of pathogenic bacteria from lower airway cultures. Caution should be exercised in the use of ofloxacin, at least in short-term treatment regimens, with anaerobic pulmonary infections; additional information is needed for S. pneumoniae given the relatively high minimal inhibitory concentrations for this species.

Effect of environmental particulates on cultured human and bovine endothelium. Cellular injury via an oxidant-dependent pathway

The effects of respirable environmental fibers on cultures of human umbilical vein and bovine pulmonary artery endothelial cell monolayers were studied. Interaction among endothelial cell monolayers and amosite and chrysotile asbestos, attapulgite, fiberglass, or latex beads resulted in rapid phagocytosis of the particulates. A gradient of time-dependent and concentration-dependent endothelial cell injury (measured by specific 51Cr release) was observed with amosite and attapulgite being markedly toxic. Chrysotile and fiberglass were much less toxic, and latex beads were not significantly injurious at any time or dose examined. Responses of bovine pulmonary artery and human endothelial vein endothelial cells to fiber phagocytosis and fiber-induced injury were similar. In human umbilical cell monolayers, fiber-mediated stimulation of the arachidonate metabolite prostacyclin paralleled endothelial cell injury; i.e. amosite and attapulgite were stimulatory, whereas fiberglass (0-500 micrograms/ml) and latex beads (10(9) beads/ml) did not significantly increase prostacyclin generation. Although chrysotile was only weakly cytotoxic, significant stimulation of prostacyclin was observed at the highest dose tested (500 micrograms/ml). To investigate whether toxic oxygen species may be involved in fiber-induced cytotoxicity, oxidant scavengers or inhibitors were used in injury studies. Both superoxide dismutase (a scavenger of O2-) and catalase (an inhibitor of H2O2) produced significant protection against fiber-mediated endothelial cell injury. In addition, chelation by deferoxamine of elemental Fe present in the fiber preparations was also protective, suggesting Fe, via the modified Haber-Weiss reaction, may promote hydroxyl radical formation and contribute to endothelial cell injury induced by these particulates. These results suggest that the interaction within the interstitial environment between endothelial cells and occupationally relevant dusts may be important in fiber-mediated inflammatory processes in the lung.

Alveolar macrophages from patients with asbestos exposure release increased levels of leukotriene B4

The alveolar influx and subsequent activation of inflammatory cells such as neutrophils and eosinophils are believed to be important in the pathogenesis of many interstitial lung disorders, including asbestosis. Indices of lower respiratory tract abnormalities detected by bronchoalveolar lavage (BAL) were investigated in 93 asbestos-exposed workers as well as in smoking (n = 12) and nonsmoking (n = 10) control subjects. Patients with clinical asbestosis (n = 12) exhibited increases in both BAL neutrophils and BAL eosinophils, expressed as both percentage of total cells and total numbers, when compared to asbestos-exposed workers without asbestosis (n = 81) and control subjects. Significantly greater numbers of BAL neutrophils were also found in asbestos-exposed workers without asbestosis than in either smoking or nonsmoking control subjects. These abnormalities correlated significantly with in vitro BAL alveolar macrophage production of the potent leukocyte chemotaxin, leukotriene B4 (LTB4). For example, basal, unstimulated LTB4 production was 3.1 +/- 0.8 ng/10(6) alveolar macrophages for patients with asbestosis, 1.05 +/- 0.2 ng/10(6) cells in asbestos workers without asbestosis, 0.9 +/- 0.2 ng/10(6) cells in control nonsmokers, and 0.2 +/- 0.05 ng/10(6) cells in control smokers. Stimulated LTB4 release from BAL alveolar macrophages (A23187 or arachidonate) was even more pronounced in asbestos workers with or without asbestosis, suggesting an in vivo priming effect on alveolar macrophage synthesis of LTB4. Cell-free BAL supernatants from asbestos-exposed patients with or without asbestosis also contained significantly greater amounts of LTB4 than did those from control subjects, indicating enhanced in vivo production of this inflammatory mediator.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinopeptide A reactive peptides and procoagulant activity in bronchoalveolar lavage: relationship to rheumatoid interstitial lung disease

Extravascular, primarily, alveolar fibrin deposition is commonly associated with the alveolitis of many interstitial lung diseases including the interstitial lung disease associated with rheumatoid arthritis (RA). We therefore hypothesized that coagulation pathways, which promote fibrin formation, would be activated in the alveolar lining fluids of patients with rheumatoid interstitial lung disease. To test this hypothesis, we studied the bronchoalveolar lavage (BAL) fluids from patients with rheumatoid interstitial lung disease (n = 7) and patients with RA unassociated with interstitial lung disease (n = 10) to characterize and quantitatively compare the BAL procoagulant material and levels of fibrinopeptide A (FPA), which is cleaved from fibrinogen by thrombin. FPA reactive peptide concentrations were significantly greater in rheumatoid interstitial lung disease than RA when normalized per ml of concentrated BAL fluid (p = 0.02), per mg BAL total protein (p = 0.01) or BAL albumin content (p = 0.03) and correlated with BAL antigenic neutrophil elastase concentrations (r = 0.87). Procoagulant activity was present in similar concentration of BAL of patients with RA and rheumatoid interstitial lung disease and was mainly attributable to tissue factor associated with factor VII (or VIIa). Our results demonstrate that tissue factor and factor VII are endogenous in the alveoli of subjects with RA and interstitial lung disease and could interact with distal coagulation substrates which may enter the alveoli in interstitial lung disease to locally promote fibrin deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Asbestos-induced endothelial cell activation and injury. Demonstration of fiber phagocytosis and oxidant-dependent toxicity

Vascular endothelial cell injury is important in the development of a variety of chronic interstitial lung disorders. However, the involvement of such injury in the inflammatory response associated with the inhalation of asbestos fibers is unclear and the mechanism of asbestos fiber cytotoxicity remains unknown. In the present study, human umbilical vein endothelial cells were challenged with amosite asbestos and several parameters of cellular function were examined. Electron microscopic examination revealed that endothelial cell exposure to asbestos resulted in active phagocytosis of these particulates. Biochemical evidence of dose-dependent asbestos-mediated endothelial cell activation was indicated by increased metabolism of arachidonic acid. For example, amosite asbestos (500 micrograms/ml) produced a ninefold increase in prostacyclin (PGI2) levels over those levels in non-exposed cells. Incubation of human endothelial cells with asbestos fibers induced specific 51Cr release in both a dose- and time-dependent fashion indicative of cellular injury. Injury induced by amosite asbestos was not significantly attenuated by treatment of the endothelial cell monolayer with either the iron chelator deferoxamine, which prevents hydroxyl radical (.OH) formation, or by the superoxide anion (O2-) scavenger, superoxide dismutase. However, significant dose-dependent protection was observed with the hydrogen peroxide (H2O2) scavenger, catalase. Chelation of elemental iron present within amosite asbestos fibers by deferoxamine produced a 33% reduction in asbestos cytotoxicity, suggesting a potential role for hydroxyl radical-mediated injury via the iron-catalyzed Haber-Weiss reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of platelet activating factor on leukocyte-endothelial cell interactions

The proinflammatory effects of platelet activating factor (PAF) that impact upon tissue inflammation were studied in vitro using the adherence of human neutrophils to endothelium and the increase in macromolecule permeability of endothelial monolayers. PAF produced both a time- and dose-dependent increase in neutrophil-endothelial cell adhesion. The adhesion promoting properties observed were primarily due to an effect of PAF on endothelium and not on neutrophils and was independent of endothelial cell cyclooxygenase products. The PAF receptor antagonist kadsurenone inhibited the adhesion response suggesting endothelial surface PAF receptors are involved in these responses. Whereas PAF alone did not alter endothelial cell barrier properties, leukocyte activation (neutrophil and platelets) with PAF produced significant increases in 125I-albumin clearance across endothelial monolayers. These studies suggest that PAF has potent proinflammatory effects and that it can play a significant role in the endothelial response to injury.

Inflammatory events after fibrin microembolization. Alterations in alveolar macrophage and neutrophil function

We performed bronchoalveolar lavage (BAL) 0.5 to 24 h after thrombin-induced pulmonary microembolization in spontaneously breathing sheep to examine the inflammatory events that occur after pulmonary intravascular coagulation. Neutrophil alveolitis was evident as early as 0.5 h after microembolization and was maximal at 4 h (4.9 +/- 1.5% neutrophils of total BAL cells at baseline versus 26.2 +/- 2.8% at 4 h post-thrombin). Neutrophils obtained both at baseline (isolated from peripheral blood) and at 0.5 to 24 h after thrombin (isolated from BAL) did not demonstrate significant basal production of superoxide anion (O2-) and produced similar amounts of O2- upon challenge with phorbol myristate acetate (PMA) 200 micrograms/ml. The basal O2- production by alveolar macrophages was also not increased. However, alveolar macrophages recovered after fibrin microembolization produced greater amounts of O2- (29.1 +/- 6.3 nm O2-/10(6) cells at 0.5 h) after challenge with PMA compared with alveolar macrophages recovered prior to embolization (10.6 +/- 1.6 nm O2-/10(6) cells baseline), suggesting that thrombin-induced microembolization primes alveolar macrophages and enhances their O2- generation. Neutrophil chemotactic activity was detected in BAL fluid at 0.5 h post-microembolization and reached a peak level at 2 h. Alveolar macrophages were a source of the chemotactic activity since conditioned medium obtained from 2-h post-thrombin macrophages induced neutrophil chemotaxis, whereas baseline cells did not. The addition of the thrombin to macrophages did not result in the generation of chemotactic activity from baseline macrophages, indicating that macrophages were activated during the process of intravascular coagulation rather than by thrombin per se. Post-thrombin BAL fluid also stimulated O2- generation from sheep neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthmatic bronchitis

Asthmatic bronchitis is a term that encompasses a large number of patients who generally smoke cigarettes and demonstrates chronic mucous hypersecretion and airway hyperreactivity. These patients are frequently labelled simply as asthmatic. In this setting, however, "asthma" is a nonspecific term applied to patients with a variety of symptoms. On the basis of history, bronchodilator response, and response to bronchoprovocating agents, it is frequently difficult to differentiate between groups of chronic bronchitics and asthmatics. Subjects with chronic bronchitis clearly demonstrate bronchial hyperreactivity to bronchoprovocating agents. This response does not appear to be due to an abnormality in bronchial smooth muscle. Chronic bronchitics may also respond to a variety of bronchodilating agents, again demonstrating the presence of bronchial hyperreactivity. Potential mechanisms for the observed bronchial hyperreactivity include reduced airway caliber, reduced resistance to airway narrowing, and airway inflammation. Airway inflammation may be the common link between airflow obstruction and airway hyperreactivity frequently seen in these patients. The finding of airway hyperreactivity in chronic bronchitis has implications far beyond simple therapeutic considerations and may lead to a better understanding of bronchial hyperreactivity under any circumstance.

Ampicillin, tetracycline, and chloramphenicol resistant Haemophilus influenzae in adults with chronic lung disease. Relationship of resistance to prior antimicrobial therapy

Antibiotic resistance in 1,003 sputum isolates of Haemophilus influenzae from adults with chronic lung disease was assessed from January 1983 through June 1986. The incidence of resistance was 3.2% for tetracycline, 0.6% for chloramphenicol, and 12.5% for ampicillin. Resistance to ampicillin or tetracycline usually occurred alone, while 100% of chloramphenicol resistant isolates were co-resistant to tetracycline or ampicillin. More than 90% of antibiotic resistant isolates were nontypable and belonged to biotypes II, III, or V. Chart reviews of 331 patients revealed that patients with ampicillin resistant isolates were more likely than control subjects to have received ampicillin in the prior 6 wk (33% versus 6%, p less than 0.0001), whereas patients with isolates resistant to tetracycline or chloramphenicol plus tetracycline were more likely to have received tetracycline than control subjects (24% and 50%, respectively, versus 5%, p less than 0.005). The incidence of ampicillin resistance and the reluctance of physicians caring for adults to use chloramphenicol suggests that a newer cephalosporin such as cefotaxime may be the initial therapy of choice for severe H. influenzae disease in our patient population.

Substance P-induced pulmonary vasoreactivity in isolated perfused guinea pig lung

We examined the effects of the neuropeptide substance P on pulmonary hemodynamic and transvascular fluid filtration in isolated Ringer's-perfused and blood-enriched Ringer's-perfused guinea pig lung and on albumin flux across bovine pulmonary artery endothelial monolayer. Mean pulmonary artery, left atrial, and capillary pressures were determined and used to calculate arterial and venous resistances, and lung weight was continuously monitored. Substance P (0.01-1.0 microM) caused marked increases in pulmonary arterial pressure, capillary pressure, venous resistance, and lung weight within 3-5 minutes after administration. These responses remained elevated above baseline at the end of the 30-minute experimental period in the Ringer's-perfused lungs but not in the blood-enriched Ringer's-perfused lungs. Substance P did not alter the capillary filtration coefficient in isolated lungs and transendothelial albumin permeability in the endothelial monolayer. Substance P resulted in an increase in venous effluent thromboxane B2 concentrations in perfused lungs but had no effect on 6-keto-prostaglandin F1 alpha concentrations. Papaverine (0.27 mM) (a smooth-muscle relaxant) abolished the pulmonary microvascular response to substance P in Ringer's-perfused lungs, and meclofenamate (0.15 mM) (a cyclooxygenase inhibitor) attenuated the pulmonary vasoconstriction and lung weight increase. Pyrilamine (1.0 microM) (a histamine1-receptor antagonist) did not alter the responses to substance P. In conclusion, substance P does not affect pulmonary vascular permeability to water and protein. Substance P induces an intense pulmonary vasoconstriction (due to greater constriction of postcapillary vessels) and an elevation in pulmonary capillary pressure that increases net transvascular fluid filtration.(ABSTRACT TRUNCATED AT 250 WORDS)

Procoagulant activity in bronchoalveolar lavage in the adult respiratory distress syndrome. Contribution of tissue factor associated with factor VII

Alveolar fibrin deposition commonly occurs in the lungs of patients with the adult respiratory distress syndrome (ARDS). Bronchoalveolar lavage (BAL) from patients with ARDS, control patients with interstitial lung disease (ILD), congestive heart failure, or exposure to hyperoxia, and normal healthy subjects was studied to determine whether local alterations in procoagulant activity favor alveolar fibrin deposition in the lungs in ARDS. Procoagulant activity capable of shortening the recalcification time of plasma deficient in either factor VII or factor VIII was observed in unconcentrated BAL of all patients, but was significantly greater in BAL from patients with ARDS when compared with that of control subjects (p less than 0.001). Unconcentrated BAL from patients with ARDS shortened the recalcification time of plasma deficient in factor X, but no functional thrombin was detectable. BAL procoagulant from patients with ARDS was inhibited by concanavalin A, an inhibitor of tissue factor. The hydrolysis of purified human factor X by BAL from the ARDS and other patient groups was determined by measuring the amidolytic activity of generated factor Xa on its N-benzoyl-L-isoleucyl-L-glutamyl-glycyl-L-arginine-p-nitroanilide substrate. The procoagulant activity of BAL was associated with the development of amidolytic activity, indicating activation of factor X. BAL from patients with ARDS contained more factor X activating activity than did BAL from control groups (p less than 0.001). This activity was calcium dependent and was maximal at 1 mM ionized calcium. The BAL factor X activating activity was most active at neutral pH and was sedimented by ultracentrifugation at 100,000 x g.(ABSTRACT TRUNCATED AT 250 WORDS)

Lower respiratory tract abnormalities in rheumatoid interstitial lung disease. Potential role of neutrophils in lung injury

Although the etiology of rheumatoid interstitial lung disease (RILD) remains unknown, bronchoalveolar lavage (BAL) has been useful in studying potentially pathogenic mechanisms in this disorder. Previous investigations in patients with rheumatoid arthritis (RA) and RILD revealed abnormal BAL T-lymphocyte subpopulations and a significant elevation in BAL neutrophils. Because neutrophils have been implicated as important effector cells in inflammatory disorders such as ARDS and idiopathic pulmonary fibrosis, we evaluated BAL fluid in patients with RA for neutrophil chemotactic and activating properties and for evidence of neutrophil activation. The BAL fluid from patients with RILD contained significant neutrophil chemotactic activity derived from both lipid and nonlipid components. Evidence for neutrophil stimulation in the lower respiratory tract of patients with RILD was suggested by elevations in both myeloperoxidase activity and immunologically determined levels of human neutrophil elastase in BAL fluid. Free uninhibited elastolytic activity, however, was not demonstrated, suggesting that adequate protease inhibitor levels were present to inhibit active elastase activity. In addition to elevated myeloperoxidase activity, a potential role for neutrophil-derived oxidant injury was indirectly suggested by the enhanced release of superoxide anion (O2-) from resting normal human blood neutrophils challenged with concentrated BAL fluid from patients with RA and interstitial lung disease. Significant correlations were found between physiologic parameters and the percentage of BAL neutrophils, as well as levels of neutrophil-derived mediators. For example, levels of human neutrophil elastase were strongly correlated with diminished diffusion capacity (r = -0.73, p less than 0.001) and reduced forced vital capacity (r = -0.63, p less than 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar macrophage gold retention in rheumatoid arthritis

Alveolar macrophages obtained by bronchoalveolar lavage (BAL) were evaluated by electron dispersive microanalysis (EDX) for the presence of elemental gold. EDX revealed gold in 90% (9/10) of patients with RA who were currently receiving chrysotherapy or who had discontinued chrysotherapy less than 24 months before BAL. All patients who had discontinued chrysotherapy more than 24 months before BAL (range: 3-14 years) were EDX negative (4/4), as were patients with RA who had never received gold therapy (5/5). Seven patients with RA (7/19) had clinical evidence of interstitial lung disease and 12 patients (12/19) had no interstitial lung disease. There was no correlation between chrysotherapy and the development of interstitial lung disease. These results demonstrate that gold is retained for prolonged periods in pulmonary tissue macrophages but do not identify any relationship between gold and chronic rheumatoid lung disease.

Measurement of albumin permeability across endothelial monolayers in vitro

We have developed an experimental system to measure the permeability of the cultured endothelial monolayer. The luminal-to-abluminal flux of 125I-albumin across cultured pulmonary endothelium was expressed as a clearance rate equal to the permeability-surface area product. After clearance rate measurement for a 30-min base-line period, a test agent was added to the luminal side, and the clearance rate was remeasured during a 30-min experimental period. In control studies the base-line clearance rate was 0.343 +/- 0.017 microliter/min. After correction for the diffusional resistances of the filter and unstirred layers, the calculated permeability of the endothelial monolayer was 1.2 X 10(-5) cm/s. When culture medium was the test agent, the experimental clearance rate was unchanged from the base-line value. After addition of 4 mM oleic acid to the luminal chamber, the clearance rate was 0.528 +/- 0.017 microliter/min compared with a base-line value of 0.330 +/- 0.008 microliter/min (P less than 0.005). This method allows the calculation of endothelial permeability with correction for unstirred layers and the use of each monolayer as its own control.

Neutrophil collagenase in rheumatoid interstitial lung disease

Ten patients with rheumatoid arthritis were evaluated by bronchoalveolar lavage. Five patients (group I) had interstitial lung disease by physiological and radiographic criteria, whereas five (group II) had no evidence of lung disease. Lavage fluid from four of the five group I patients contained an active collagenase which by inhibitory profile and substrate specificity appeared to be of neutrophil origin. None of the group II patients demonstrated lavage fluid collagenase. Treatment of lavage fluid with trypsin failed to uncover latent collagenase activity in either group, suggesting that the collagenase is present entirely in an active form. These findings parallel those observed in idiopathic pulmonary fibrosis and suggest a potential pathogenetic role for collagenase in rheumatoid interstitial lung disease.

Platelet-activating factor increases lung vascular permeability to protein

We studied the effects of platelet-activating factor (PAF) on pulmonary hemodynamics and microvascular permeability in unanesthetized sheep prepared with lung-lymph fistulas. Since cyclooxygenase metabolites have been implicated in mediating these responses, we also examined the role of the cyclooxygenase pathway. PAF infusion (4 micrograms X kg-1 X h-1 for 3 h) produced a rapid, transient rise in pulmonary arterial pressure (Ppa), pulmonary vascular resistance (PVR), plasma thromboxane B2 concentration (TxB2), and pulmonary lymph flow (Qlym). The lymph-to-plasma protein concentration ratio (L/P) did not change from base line. Pretreatment with the cyclooxygenase inhibitor, sodium meclofenamate, prevented the generation of TxB2 and the hemodynamic changes but did not prevent the increase in Qlym. The estimated protein reflection coefficient decreased from a control value of 0.66 +/- 0.04 to 0.43 +/- 0.06 after PAF infusion. We also studied the effects of PAF on endothelial permeability in vitro by measuring the flux of 125I-albumin across cultured bovine pulmonary artery endothelial cells (EC) grown to confluency on a gelatinized micropore filter and mounted within a modified Boyden chemotaxis chamber. PAF (10(-8) to 10(-4) M) had no direct effect on EC albumin permeability, suggesting that the increase in permeability in sheep was not the direct lytic effect of PAF. In conclusion, PAF produces pulmonary vasoconstriction mediated by cyclooxygenase metabolites. PAF also increases pulmonary vascular permeability to protein that is independent of cyclooxygenase products and is not the result of a direct effect of PAF on the endothelium.

Thrombin-induced increase in albumin permeability across the endothelium

We studied the effect of thrombin on albumin permeability across the endothelial monolayer in vitro. Bovine pulmonary artery endothelial cells were grown on micropore membranes. Morphologic analysis confirmed the presence of a confluent monolayer with interendothelial junctions. Albumin permeability was measured by the clearance of 125I-albumin across the endothelial monolayer. The control 125I-albumin clearance was 0.273 +/- 0.02 microliter/min. The native enzyme, alpha-thrombin (10(-6) to 10(-10) M), added to the luminal side of the endothelium produced concentration-dependent increases in albumin clearance (maximum clearance of 0.586 +/- 0.08 microliter/min at 10(-6) M). Gamma (gamma) thrombin (10(-6) M and 10(-8) M), which lacks the fibrinogen recognition site, also produced a concentration-dependent increase in albumin clearance similar to that observed with alpha-thrombin. Moreover, the two proteolytically inactive forms of the native enzyme, i-Pr2 P-alpha-thrombin and D-Phe-Pro-Arg-CH2-alpha-thrombin, increased the 125I-albumin clearance (0.610 +/- 0.09 microliter/min and 0.609 +/- 0.02 microliter/min for i-Pr2 P-alpha-thrombin and D-Phe-Pro-Arg-CH2-alpha-thrombin at 10(-6) M, respectively). Since the modified forms of thrombin lack the fibrinogen recognition and active serine protease sites, the results indicate that neither site is required for increased albumin permeability. The increase in albumin clearance with alpha-thrombin was not secondary to endothelial cell lysis because lactate dehydrogenase concentration in the medium following thrombin was not significantly different from baseline values. There was also no morphological evidence of cell lysis. Moreover, the increase in 125I-albumin clearance induced by alpha-thrombin was reversible by washing thrombin from the endothelium. The basis for the increased albumin permeability following the addition of alpha-thrombin appears to be a reversible change in endothelial cell shape with formation of intercellular gaps.

Bronchoalveolar lavage fluid evaluation in rheumatoid arthritis

Rheumatoid arthritis (RA), a systemic disorder of unknown cause, is associated with a variety of well-recognized pulmonary abnormalities including interstitial lung disease. To investigate possible pathogenic events in this disorder, we performed bronchoalveolar lavage (BAL) in 24 patients with classic or definite RA. Using radiographic and physiologic parameters as well as BAL cell differentials, 3 distinct groups emerged. Group I consisted of 9 patients with evidence of clinical interstitial lung involvement. Group II consisted of 5 patients without evidence of clinical interstitial lung disease (normal chest roentgenogram and functional testing) but who had abnormal BAL cellular differentials. The 10 remaining patients (Group III) had no evidence of clinical interstitial lung disease and had normal BAL cell differentials. Bronchoalveolar lavage in Group I had a significantly increased percentage of neutrophils (12.4 +/- 4.2; p less than 0.05) compared with Group II (2.4 +/- 0.8) and Group III (2.9 +/- 0.6). All patients in Group II had elevated BAL lymphocytes (24.4 +/- 6.4) compared with Group I (10.1 +/- 3.8; p greater than 0.05) and Group III (5.4 +/- 0.7; p less than 0.01). Both Groups I and II had detectable IgM in BAL (0.02 +/- 0.01 and 0.04 +/- 0.02 mg/mg of albumin, respectively), whereas Group III patients and normal control subjects did not (p less than 0.01). There was a marked reduction in BAL T-lymphocyte Leu 3/Leu 2A (helper/suppressor) cell ratios in Group I (0.92 +/- 0.02; p less than 0.05) compared with Group II (2.6 +/- 0.6) and Group III (1.6 +/- 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracic gas volume measurement. Increased variability in patients with obstructive ventilatory defects

We measured the thoracic gas volume (FRC) in normal subjects and patients by body plethysmography to determine the within-subject variability and to identify factors which might influence the variability. The coefficient of variation (CV), a measure of variability, was significantly greater in patients with obstructive ventilatory defects than in patients with restrictive ventilatory defects and normal subjects, and there was a direct correlation between the CV and the FRC and an inverse correlation between the CV, the FEV1/FVC, and the FEV1. These results suggest that the disease state and its severity influence the variability in FRC measurements and that both factors should be considered in the interpretation of serial pulmonary function studies measuring lung volumes.