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Biomedical subjects

Werner Seeger

Publications and source records attributed to Werner Seeger.

At least 109 records · Page 6Linked to original sources
PubMed2003

Parenteral nutrition with fish oil modulates cytokine response in patients with sepsis.

Infusion of fish oil-based (n-3) lipids may influence leukocyte function and plasma lipids in critical care patients. Twenty-one patients with sepsis requiring parenteral nutrition were randomized to receive an n-3 lipid emulsion rich in eicosapentaenoic acid and docosahexaenoic acid or a conventional (n-6) lipid emulsion (index fatty acid: arachidonic acid) for 5 days. The impact on plasma-free fatty acids, mononuclear leukocyte cytokine generation, and membrane fatty acid composition was examined. Cytokine synthesis by isolated mononuclear leukocyte was elicited by endotoxin. Before the onset of lipid infusion therapy, plasma-free fatty acid concentrations were greatly increased in septic patients, with arachidonic acid by far surpassing eicosapentaenoic acid and docosahexaenoic acid, a feature maintained during conventional lipid infusion. Within 2 days of fish oil infusion, free n-3 fatty acids increased, and the n-3/n-6 ratio was reversed, with rapid incorporation of n-3 fatty acids into mononuclear leukocyte membranes. Generation of proinflammatory cytokines by mononuclear leukocytes was markedly amplified during n-6 and was suppressed during n-3 lipid application. After termination of lipid administration, free n-3 fatty acid concentrations and mononuclear leukocyte cytokine synthesis returned to preinfusion values. Use of lipid infusions might allow us to combine intravenous alimentation with differential impact on inflammatory events and immunologic functions in patients with sepsis.

Critical Illness↗
PubMed2003

Sildenafil for long-term treatment of nonoperable chronic thromboembolic pulmonary hypertension.

Only a small percentage of patients with chronic thromboembolic pulmonary hypertension are eligible for pulmonary thrombendarterectomy. We investigated the effects of oral sildenafil on hemodynamics and exercise capacity in 12 nonoperable chronic thromboembolic pulmonary hypertension patients. All patients were in disease progression despite sufficient long-term anticoagulation and the best supportive care and suffered from severe pulmonary hypertension (pulmonary vascular resistance index 1,935 +/- 228 dyn. s. cm-5. m2, cardiac index 2.0 l. min-1. m-2, 6-minute walking distance 312 +/- 30 m). After approximately 6 months of sildenafil treatment, pulmonary hemodynamics and exercise capacity improved significantly (pulmonary vascular resistance index 1,361 +/- 177 L. min-1. m2, p = 0.004, cardiac index 2.4 +/- 0.2 L. min-1. m-2, p = 0.009, 6-minute walking distance 366 +/- 28 m, p = 0.02). Therefore, oral sildenafil may offer a new option for medical treatment of this devastating disease.

Female↗
PubMed2003

Nebulization of biodegradable nanoparticles: impact of nebulizer technology and nanoparticle characteristics on aerosol features.

Nanoparticles may be effective drug delivery systems for use in various pulmonary therapeutic schemes. This study investigated the effect of nebulization technology and nanoparticle characteristics on the features of aerosol generation. Suspensions of biodegradable nanoparticles consisting of commercially available poly(lactide-co-glycolide) and novel comb polymers were nebulized with a jet, ultrasonic, and piezo-electric crystal nebulizer. The effects of the nanoparticle suspensions on the aerosol droplet size, as well as the nanoparticle size before and after nebulization, were characterized via laser diffraction. While the individual nanoparticle suspensions showed no clinically relevant influence on aerosol droplet size, as compared to control experiments, an enhanced nanoparticle aggregation within the droplets was observed. This aggregation was further characterized by fluorescence and scanning electron microscopy. Dependency of aggregation on nebulizer technology and nanoparticle characteristics was noted. Nanoparticles exhibiting the highest surface hydrophobicity were particularly susceptible to aggregation when nebulized with a jet nebulizer. Aggregation was reduced with nanoparticles exhibiting a more hydrophilic surface or when using ultrasonic nebulizers. We conclude that the biodegradable nanoparticles contained in the suspensions did not affect the aerosol droplet size in a clinically relevant manner; however, both the nanoparticle characteristics and the technique of aerosol generation influence nanoparticle aggregation occurring during aerosolization.

Aerosols↗
PubMed2003

Changes in biochemical and biophysical surfactant properties with cardiopulmonary bypass in children.

OBJECTIVE: The aim of the present study was to characterize pulmonary surfactant properties in children undergoing cardiovascular surgery with cardiopulmonary bypass. DESIGN: Prospective clinical trial. SETTING: University hospital pediatric intensive care unit. PATIENTS: Fifty pediatric patients with congenital cardiac defects undergoing cardiovascular surgery with (n = 35) and without (n = 15) cardiopulmonary bypass procedure. INTERVENTIONS: Tracheal aspirates were collected by saline lavage during routine suctioning before (baseline) and after cardiopulmonary bypass, as well as 4, 8, and 24 hrs after admission to the pediatric intensive care unit. MEASUREMENTS AND MAIN RESULTS: Total protein and phospholipid concentrations were assessed in native tracheal aspirates, in large surfactant aggregates, and in small surfactant aggregates. Phospholipid profiles and phosphatidylcholine fatty acids; surfactant apoproteins SP-A, SP-B, and SP-C (enzyme-linked immunosorbent assay); and surface activity (Pulsating Bubble Surfactometer) were all analyzed in large surfactant aggregates. With cardiopulmonary bypass, an initial increase in total protein content was followed by an increase in phospholipid concentration in tracheal aspirates. Large surfactant aggregates decreased 4 hrs after cardiopulmonary bypass (4 hrs, 22.6 +/- 5.6%; mean +/- SEM; p<.01 compared with baseline, 55.4 +/- 9.2%) but recovered within 24 hrs. The phospholipid-protein ratio of large surfactant aggregates 24 hrs after cardiopulmonary bypass (1.2 +/- 0.2; p<.01) was significantly decreased compared with baseline (2.9 +/- 0.6). The relative amount of phosphatidylglycerol content in the large surfactant aggregates-fraction dropped linearly over time but other phospholipids remained mainly unchanged. Phosphatidylcholine fatty acid profiles remained unaffected by cardiopulmonary bypass. The relative content of SP-B and SP-C in large surfactant aggregates increased approximately three-fold compared with baseline. Altogether, our findings with recovered large surfactant aggregate/small surfactant aggregate ratios and increased phospholipid in tracheal aspirates after 24 hrs represent an approximately ten-fold increase in large surfactant aggregate-associated SP-B and SP-C compared with baseline. Only minor changes were detected in biophysical properties of large surfactant aggregates throughout the observation period. CONCLUSIONS: Cardiopulmonary bypass procedure in children induces profound changes in the surfactant system involving both phospholipid and protein components; biophysical function may have been maintained by compensatory increase in SP-B and SP-C.

Cardiopulmonary Bypass↗
PubMed2003

Leukotriene-mediated coronary vasoconstriction and loss of myocardial contractility evoked by low doses of Escherichia coli hemolysin in perfused rat hearts.

OBJECTIVE: hemolysin has been implicated as an important pathogenic factor in extraintestinal infections including sepsis. We investigated the effects of coronary administration of hemolysin on cardiac function in isolated rat hearts perfused at constant flow. DESIGN: Prospective, experimental study. SETTING: Research laboratory at a university hospital. SUBJECTS: Isolated hearts from male Wistar rats. INTERVENTIONS: Isolated hearts were perfused with purified hemolysin for 60 min. MEASUREMENTS AND MAIN RESULTS: Low concentrations of the toxin in the perfusate (0.1-0.2 hemolytic units/mL) caused a dose-dependent coronary vasoconstriction with a marked increase in coronary perfusion pressure, which was paralleled by a decrease in left ventricular developed pressure (and the maximum rate of left ventricular pressure increase). Moreover, 0.2 hemolytic units/mL hemolysin evoked ventricular fibrillation within 10 mins of toxin application. These events were accompanied by the liberation of leukotrienes (LTC4, LTD4, LTE4, and LTB4), thromboxane A2, prostaglandin I2, and the cell necrosis markers lactate dehydrogenase and creatine kinase into the recirculating perfusate. The lipoxygenase inhibitor MK-886 fully blocked the toxin-induced coronary vasoconstrictor response and the loss of myocardial contractility and reduced the release of lactate dehydrogenase and creatine kinase. In contrast to this, the cyclooxygenase inhibitor indomethacin was entirely ineffective. In addition, hemolysin elicited an increase in heart weight and left ventricular end-diastolic pressure, the latter again being suppressed by MK-886. CONCLUSIONS: Low doses of hemolysin cause strong coronary vasoconstriction, linked with loss of myocardial performance, release of cell injury enzymes, and electrical instability, with all events being largely attributable to toxin-elicited leukotriene generation in the coronary vasculature. Bacterial exotoxins such as hemolysin thus may be implicated in the cardiac abnormalities encountered in septic shock.

Animals↗
PubMed2003

Cyclooxygenase-2-dependent and thromboxane-dependent vascular and bronchial responses are regulated via p38 mitogen-activated protein kinase in control and endotoxin-primed rat lungs.

Mitogen-activated protein kinases (MAPKs) are part of an intracellular signaling machinery consisting of three known distinct pathways, each leading to activation of a different protein kinase: p38, ERK (extracellular signal-regulated kinase), or JNK (c-Jun N-terminal kinase). We investigated the role of the p38 MAPK pathway in the phenomenon of lung endotoxin "priming": incubation of perfused rat lungs with lipopolysaccharide (LPS) for 2 hours results in drastically enhanced cyclooxygenase-2-dependent and thromboxane synthase-dependent vasoconstriction and bronchoconstriction, including edema formation in response to a second inflammatory stimulus, such as arachidonic acid application. Two unrelated selective inhibitors of p38 (SB203580 and SC-68376) dose dependently suppressed the arachidonic acid-induced pulmonary artery pressor response, edema formation, and bronchoconstrictor response in both control lungs and lungs that underwent preceding endotoxin priming. In parallel, thromboxane, but not prostacyclin, released into the lung perfusate was dose dependently inhibited. Using immunohistochemical techniques in combination with quantitative microdensitometry, p38 was detected in nearly all cell types in control lungs, whereas the activated form p-p38 was only expressed in certain cell types, eg, bronchial epithelial cells, endothelial cells, alveolar macrophages, and vascular smooth muscle cells (SMC) of small vessels. In response to endotoxin, p-p38 expression was additionally observed in septal cells, bronchial SMC, and vascular SMC of larger pulmonary vessels and was increased in most other cell types including small-vessel SMC. We conclude that both immunolocalization of p38 activity and pharmacologic interventions support a strong role of the p38 MAPK pathway in establishing an active cyclooxygenase-2/thromboxane synthase axis in vascular and bronchial SMC, with up-regulation of this signaling cascade occurring in LPS priming and being responsible for enhanced pulmonary artery pressor response, edema formation, and bronchoconstriction. Moreover, LPS induces or increases phosphorylation of p38 in other lung cell types. The physiologic consequences of these events remain to be established.

Animals↗
PubMed2003

Increased neutrophil mediator release in patients with pulmonary hypertension--suppression by inhaled iloprost.

Polymorphonuclear neutrophils (PMN) have been implicated in various vascular inflammatory processes. We isolated PMN from venous blood samples of 10 patients with severe primary pulmonary arterial hypertension (PPH), 7 patients with pulmonary hypertension secondary to chronic thromboembolism (CTEPH), and 12 healthy controls. When stimulated with the calcium-ionophore A23187, platelet activating factor (PAF) or the microbial agent n-formyl-Methionyl-Leucyl-Phenylalanine (fMLP), significantly increased release of elastase and superoxide anion was noted in both groups with pulmonary hypertension. Moreover, the neutrophils of CTEPH patients responded with an enhanced liberation of leukotriene (LT) B(4) and 5-hydroxyeicosatetraenoic acid (5-HETE). Inhalation of aerosolized iloprost (5 microg) caused a rapid decline in pulmonary vascular resistance, in both PPH and CTEPH. This hemodynamic response was paralleled by a significant suppression of ionophore- and ligand-induced elastase and superoxide release, as well as LTB(4) and 5-HETE formation. The neutrophil inhibitory effect of the inhalation maneuver was fully reproduced by in vitro incubation of neutrophils with 1-10 pg/ml iloprost for 2 hours. This is the first study to demonstrate that circulating neutrophils from patients with PPH and CTEPH possess an enhanced readiness to respond with inflammatory mediator generation to different stimulatory agents ex-vivo, and that PMN respiratory burst, elastase secretion and leukotriene generation are promptly reduced by an iloprost inhalation maneuver. Neutrophils might participate in the inflammatory processes in pulmonary arterial hypertension.

Administration, Inhalation↗
PubMed2003

Selective inhibition of large-to-small surfactant aggregate conversion by serine protease inhibitors of the bis-benzamidine type.

Conversion of the biophysically active large surfactant aggregate subtype (LA) of alveolar surfactant into the less surface active small surfactant aggregates (SA) occurs in vivo and is reproduced under conditions of cyclic surface area changes in vitro. A serine-active carboxyl esterase has been suggested as the responsible enzymatic activity, although the exact mechanisms underlying the conversion process are presently unclear. We investigated the influence of exogenous serine proteases and synthetic and natural serine protease inhibitors on the conversion kinetics of natural rabbit surfactant, obtained as bronchoalveolar lavage fluid (BALF). In vitro cycling of BALF was performed for various time periods in the absence or presence of increasing amounts of several serine proteases (trypsin, plasmin, thrombin, tryptase), and one natural (aprotinin) and 25 synthetic serine protease inhibitors (including regular benzamidines [group A], 3-amidinophenylalanine derivatives [group B], bis-benzamidines [group C], and analogs of naphthylsulfonyl-glycyl-4-amidinophenylalanine piperidide [group D]). LA were separated from SA by 48,000 x g centrifugation. Surface activity of the LA fraction was measured by means of the pulsating bubble surfactometer. None of the "classical" serine proteases forwarded any acceleration of the LA-to-SA conversion kinetics. Some of the serine protease inhibitors caused moderate retardation of conversion, but at the same dose range inhibited the surface tension-lowering properties of the LA fraction, which per se explained their inhibitory effect. In contrast, specific dose-dependent inhibition of the LA-to-SA transition was observed for four derivatives of the bis-benzamidine group: full blockage of conversion over 240 min of cycling was noted at doses that did not interfere with the surface activity of the LA fraction. In addition, the prototype of these bis-benzamidines, 1,4-bis-[beta-naphthylsulfonyl-(3-aminophenylalanine)]-piperazide, was found to inhibit the activity of the rabbit liver carboxylesterase ES-2 in two different synthetic substrate assays reflecting the amidase and esterase properties of carboxylesterases. These findings support the hypothesis that the LA-to-SA conversion is an enzymatically-driven process with serine-active carboxyl esterase(s) being centrally involved. Synthetic bis-benzamidine-type serine protease inhibitors may offer specific inhibition of this event.

Animals↗
PubMed2003

Chemical crosslinking of urokinase to pulmonary surfactant protein B for targeting alveolar fibrin.

Intraalveolar fibrin formation is a consistent finding in acute inflammatory and chronic interstitial lung disease. Polymerization of fibrin in the presence of pulmonary surfactant results in far-reaching incorporation of the hydrophobic surfactant compounds into the growing fibrin matrix, with loss of surface activity, altered fibrin structure and reduced susceptibility of the clot to fibrinolysis. For specific targeting of such alveolar fibrin, we designed a hybrid molecule consisting of the catalytic domain of urokinase (B-chain) and the hydrophobic surfactant protein B (SP-B), termed SPUC. The urokinase B-chain, obtained by limited reduction of human two-chain-urokinase (u-PA) and subsequent affinity purification, was chemically coupled to SP-B in a semi-organic solvent system using a hetero-bifunctional crosslinker. Purification of the chimeric proteins included reversed phase and cation exchange chromatography. SDS-PAGE and Western Blotting with immunostaining were employed for biochemical characterization of the conjugate. Chromogenic substrate assays, (125)I-based fibrin plate assays, active site titration and surface tension measurements (pulsating bubble surfactometer) were performed to analyze the specific fibrinolytic activity of the conjugate and its surface activity. SPUC was found i) to be assembled stoichiometrically in a 1: 1 fashion (SP-B: u-PA), ii) to fully retain the biophysical activity as compared to native SP-B and iii) to also retain the fibrinolytic activity. SPUC was 2-3 fold more effective in lysis of surfactant containing clots and 5-fold more resistant against plasminogen activator 1 (PAI-1) as compared to the native u-PA. We conclude that urokinase and SP-B can be chemically crosslinked, thereby yielding a fibrinolytic enzyme suitable for targeting alveolar fibrin.

Chromogenic Compounds↗
PubMed2002

Downregulation of hypoxic vasoconstriction by chronic hypoxia in rabbits: effects of nitric oxide.

Hypoxic pulmonary vasoconstriction (HPV) matches lung perfusion to ventilation for optimizing pulmonary gas exchange. Chronic alveolar hypoxia results in vascular remodeling and pulmonary hypertension. Previous studies have reported conflicting results of the effect of chronic alveolar hypoxia on pulmonary vasoreactivity and the contribution of nitric oxide (NO), which may be related to species and strain differences as well as to the duration of chronic hypoxia. Therefore, we investigated the impact of chronic hypoxia on HPV in rabbits, with a focus on lung NO synthesis. After exposure of the animals to normobaric hypoxia (10% O(2)) for 1 day to 10 wk, vascular reactivity was investigated in ex vivo perfused normoxic ventilated lungs. Chronic hypoxia induced right heart hypertrophy and increased normoxic vascular tone within weeks. The vasoconstrictor response to an acute hypoxic challenge was strongly downregulated within 5 days, whereas the vasoconstrictor response to the thromboxane mimetic U-46619 was maintained. The rapid downregulation of HPV was apparently not linked to changes in the lung vascular NO system, detectable in the exhaled gas and by pharmacological blockage of NO synthesis. Treatment of the animals with long-term inhaled NO reduced right heart hypertrophy and partially maintained the reactivity to acute hypoxia, without any impact on the endogenous NO system being noted. We conclude that chronic hypoxia causes rapid downregulation of acute HPV as a specific event, preceding the development of major pulmonary hypertension and being independent of the lung vascular NO system. Long-term NO inhalation partially maintains the strength of the hypoxic vasoconstrictor response.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2002

Simvastatin inhibits inflammatory properties of Staphylococcus aureus alpha-toxin.

BACKGROUND: Simvastatin, a 3-hydroxy-methylglutaryl coenzyme A reductase inhibitor, has been shown to lower serum cholesterol levels in clinical use. Moreover, statins exert beneficial effects in vascular diseases by inhibition of leukocyte rolling, adherence, and transmigration. The aim of this study was to determine if pretreatment with simvastatin attenuates Staphylococcus aureus alpha-toxin-induced increase in leukocyte-endothelial interactions during exotoxemia. METHODS AND RESULTS: The effects of simvastatin on leukocyte-endothelial cell interactions were observed by intravital microscopy in the rat mesenteric microcirculation. Simvastatin (50 or 100 microg/kg) was administered 18 hours before the study. Activation of microcirculation was induced by bolus administration of 40 microg/kg S aureus alpha-toxin. Exotoxemia resulted in a significant and time-dependent increase in leukocyte rolling, adherence, and transmigration of leukocytes as well as P-selectin expression on the intestinal vascular endothelium. Pretreatment with simvastatin significantly inhibited exotoxin-induced leukocyte rolling from 71+/-10 to 14+/-4.7 cells/min (P<0.01) and adherence from 14+/-3.5 to 0.4+/-0.2 cells (P<0.01). In addition, simvastatin pretreatment significantly inhibited transmigration of leukocytes from 10.5+/-1.2 to 4.2+/-0.9 (P<0.05) cells. Immunohistochemical detection of endothelial cell adhesion molecule P-selectin showed a 50% decrease in endothelial cell surface expression after simvastatin treatment. Furthermore, simvastatin treatment resulted in enhanced expression of endothelial cell NO synthase III in the intestinal microcirculation. CONCLUSIONS: These results demonstrate that simvastatin interferes with exotoxin-induced leukocyte-endothelial cell interactions, which may be relevant in various infectious diseases. Statin treatment may offer a new therapeutic strategy for these clinical conditions.

Animals↗
PubMed2002

Adrenomedullin reduces endothelial hyperpermeability.

Endothelial hyperpermeability induced by inflammatory mediators is a hallmark of sepsis and adult respiratory distress syndrome. Increased levels of the regulatory peptide adrenomedullin (ADM) have been found in patients with systemic inflammatory response. We analyzed the effect of ADM on the permeability of cultured human umbilical vein endothelial cell (HUVEC) and porcine pulmonary artery endothelial cell monolayers. ADM dose-dependently reduced endothelial hyperpermeability induced by hydrogen peroxide (H2O2), thrombin, and Escherichia coli hemolysin. Moreover, ADM pretreatment blocked H2O2-related edema formation in isolated perfused rabbit lungs and increased cAMP levels in lung perfusate. ADM bound specifically to HUVECs and porcine pulmonary artery endothelial cells and increased cellular cAMP levels. Simultaneous inhibition of cAMP-degrading phosphodiesterase isoenzymes 3 and 4 potentiated ADM-dependent cAMP accumulation and synergistically enhanced ADM-dependent reduction of thrombin-induced hyperpermeability. However, ADM showed no effect on endothelial cGMP content, basal intracellular Ca2+ levels, or the H2O2-stimulated, thrombin-stimulated, or Escherichia coli hemolysin-stimulated Ca2+ increase. ADM diminished thrombin- and H2O2-related myosin light chain phosphorylation as well as stimulus-dependent stress fiber formation and gap formation in HUVECs, suggesting that ADM may stabilize the barrier function by cAMP-dependent relaxation of the microfilament system. These findings identify a new function of ADM and point to ADM as a potential interventional agent for the reduction of vascular leakage in sepsis and adult respiratory distress syndrome.

Actin Cytoskeleton↗
PubMed2002

Sildenafil for treatment of lung fibrosis and pulmonary hypertension: a randomised controlled trial.

BACKGROUND: Lung fibrosis can be complicated by pulmonary hypertension, limiting exercise tolerance and life expectancy. Furthermore, vasodilators might cause deterioration in gas exchange. Our aim was to compare acute effects of sildenafil, nitric oxide, and epoprostenol in individuals with pulmonary hypertension secondary to lung fibrosis. METHODS: We did a randomised controlled, open-label trial, in 16 individuals admitted to our hospital with pulmonary hypertension secondary to lung fibrosis. After inhalation of nitric oxide (10-20 ppm), we assigned patients to either maximum tolerated dose of intravenous epoprostenol (mean 8.0 ng/kg per min; n=8) or oral sildenafil (50 mg; n=8). Our primary objective was to assess pulmonary vasodilative potency (decrease in pulmonary vascular resistance index) of sildenafil by comparison with inhaled nitric oxide and infused epoprostenol. Analyses were by intention to treat. FINDINGS: Pulmonary vascular resistance index was reduced by nitric oxide (-21.9%, 95% CI -14.1 to -36.2), epoprostenol (-36.9%, -24.4 to -59.6), and sildenafil (-32.5%, -10.2 to -54.1). However, ratio of pulmonary to systemic vascular resistance decreased only in individuals who received nitric oxide and sildenafil. Baseline measurement of multiple-inert-gas elimination showed right-to-left shunt flow (4.8%, 0.0-28.2) and little perfusion of low ventilation(V)/perfusion(Q) areas (0.1%, 0.0-13.0). Prostacyclin increased V/Q mismatch (shunt 16.8%, 10.8-35.9; low V/Q 3.8%, 0.0-13.0) and decreased arterial oxygenation. By contrast, nitric oxide (4.5%, 0.0-18.0; 0.0%, 0.0-17.3) and sildenafil (3.3%, 0.0-11.3; 0.0%, 0.0-12.4) maintained V/Q matching, with raised arterial partial pressure of oxygen (14.3 mm Hg, -1.7 to 31.3) noted for sildenafil. We recorded no adverse events. INTERPRETATION: Sildenafil causes preferential pulmonary vasodilation and improves gas exchange in patients with severe lung fibrosis and secondary pulmonary hypertension.

Adult↗
PubMed2002

Fibrinolysis-inhibitory capacity of clot-embedded surfactant is enhanced by SP-B and SP-C.

Incorporation of pulmonary surfactant into fibrin inhibits its plasmic degradation. In the present study we investigated the influence of surfactant proteins (SP)-A, SP-B, and SP-C on the fibrinolysis-inhibitory capacity of surfactant phospholipids. Plasmin-induced fibrinolysis was quantified by means of a (125)I-fibrin plate assay, and surfactant incorporation into polymerizing fibrin was analyzed by measuring the incorporation of (3)H-labeled L-alpha-dipalmitoylphosphatidylcholine into the insoluble clot material. Incorporation of a calf lung surfactant extract (Alveofact) and an organic extract of natural rabbit large surfactant aggregates (LSA) into a fibrin clot revealed a stronger inhibitory effect on plasmic cleavage of this clot than a synthetic phospholipid mixture (PLX) and unprocessed LSA. Reconstitution of PLX with SP-B and SP-C increased, whereas reconstitution with SP-A decreased, the fibrinolysis-inhibitory capacity of the phospholipids. The SP-B effect was paralleled by an increased incorporation of phospholipids into fibrin. We conclude that the inhibitory effect of surfactant incorporation into polymerizing fibrin on its susceptibility to plasmic cleavage is enhanced by SP-B and SP-C but reduced by SP-A. In the case of SP-B, increased phospholipid incorporation may underlie this finding.

Animals↗
PubMed2002

Hypoxic pulmonary artery fibroblasts trigger proliferation of vascular smooth muscle cells: role of hypoxia-inducible transcription factors.

Chronic lung hypoxia causes vascular remodeling with pulmonary artery smooth muscle cell (SMCPA) hyperplasia, resulting in pulmonary hypertension and cor pulmonale. We investigated SMCPA and pulmonary artery adventitial fibroblasts (FBPA) for their proliferative response to hypoxia. Strong SMCPA growth occurred under hypoxic conditions in SMCPA/FBPA co-cultures, but not in SMCPA monocultures. SMCPA growth was fully reproduced by transferring serum-free supernatant from hypoxic cultured FBPA to normoxic SMCPA. Hypoxia-inducible-transcription-factor subtypes (HIF-1alpha, HIF-2alpha, HIF-3alpha) and its dependent target genes, carrying the hypoxia-responsive-element as regulatory component, were strongly activated in both hypoxic FBPA and SMCPA. HIF-transcription-factor decoy technique, employed to FBPA during hypoxic culturing, blocked the mitogenic activity of FBPA conditioned medium on SMCPA. The data suggest that hypoxia-driven gene regulation in pulmonary artery fibroblasts results in a mitogenic stimulus on adjacent pulmonary artery smooth muscle cells, and HIF-transcription-decoy may offer a new therapeutic approach to suppress these events.

Basic Helix-Loop-Helix Proteins↗
PubMed2002

Inhaled iloprost for severe pulmonary hypertension.

BACKGROUND: Uncontrolled studies suggested that aerosolized iloprost, a stable analogue of prostacyclin, causes selective pulmonary vasodilatation and improves hemodynamics and exercise capacity in patients with pulmonary hypertension. METHODS: We compared repeated daily inhalations of 2.5 or 5.0 microg of iloprost (six or nine times per day; median inhaled dose, 30 microg per day) with inhalation of placebo. A total of 203 patients with selected forms of severe pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (New York Heart Association [NYHA] functional class III or IV) were included. The primary end point was met if, after week 12, the NYHA class and distance walked in six minutes were improved by at least one class and at least 10 percent, respectively, in the absence of clinical deterioration according to predefined criteria and death. RESULTS: The combined clinical end point was met by 16.8 percent of the patients receiving iloprost, as compared with 4.9 percent of the patients receiving placebo (P=0.007). There were increases in the distance walked in six minutes of 36.4 m in the iloprost group as a whole (P=0.004) and of 58.8 m in the subgroup of patients with primary pulmonary hypertension. Overall, 4.0 percent of patients in the iloprost group (including one who died) and 13.7 percent of those in the placebo group (including four who died) did not complete the study (P=0.024); the most common reason for withdrawal was clinical deterioration. As compared with base-line values, hemodynamic values were significantly improved at 12 weeks when measured after iloprost inhalation (P<0.001), were largely unchanged when measured before iloprost inhalation, and were significantly worse in the placebo group. Further significant beneficial effects of iloprost treatment included an improvement in the NYHA class (P=0.03), dyspnea (P=0.015), and quality of life (P=0.026). Syncope occurred with similar frequency in the two groups but was more frequently rated as serious in the iloprost group, although this adverse effect was not associated with clinical deterioration. CONCLUSIONS: Inhaled iloprost is an effective therapy for patients with severe pulmonary hypertension.

Administration, Inhalation↗
PubMed2002

The role of CC chemokine receptor 2 in alveolar monocyte and neutrophil immigration in intact mice.

The CC chemokine ligand 2 (CCL2) (JE, monocyte chemotactic protein-1 [MCP-1]) and its CC chemokine receptor 2 (CCR2) are critical regulators of monocyte/macrophage trafficking. Recently, we demonstrated that application of exogenous CCL2 in the lungs of mice induced monocyte accumulation in the airspace, whereas combined bronchoalveolar instillation of CCL2 and Escherichia coli endotoxin provoked both enhanced monocyte accumulation and extensive neutrophil influx associated with loss of pulmonary endothelial/epithelial barrier function. In this study, we investigated the role of the CCL2 receptor CCR2 in alveolar leukocyte traffic. In CCR2 knockout mice or wild-type mice treated with the anti-CCR2-blocking monoclonal antibody MC21, monocyte accumulation in response to alveolar CCL2 or CCL2 plus endotoxin was inhibited by more than 90%. Unexpectedly, alveolar neutrophil accumulation in the CCL2/lipopolysaccharide (LPS) model was also drastically reduced by both approaches of CCR2 function interference. When wild-type mice treated with anti-Gr-1 monoclonal antibody to deplete neutrophils selectively or treated with antileukinate, a CXC receptor inhibitor, were challenged with alveolar CCL2 plus LPS, alveolar monocyte accumulation was markedly decreased. Wild-type mice treated with MC21 to block CCR2 function or with anti-Gr-1 to deplete neutrophils did not exhibit the vascular leakage that typically accompanies inflammation triggered by CCL2 and LPS in wild-type mice. These findings confirm a central role for CCR2 in the process of alveolar monocyte recruitment in response to CCL2 alone and combined CCL2 plus LPS and reveal a previously unobserved interdependence between monocyte and neutrophil trafficking that has important implications for the concomitant increase in vascular permeability.

Acute Disease↗