Macrophage activation is associated with increased secretion of monokines, proteases, arachidonic acid metabolites, reactive oxygen, and nitrogen intermediates and yet decreased secretion of apolipoprotein E (apo E). Although the kinetics of apo E down-regulation have been investigated, the mechanism(s) involved remains unknown. In the present study, the question of whether macrophage-activating factors such as lipopolysaccharide (LPS) and granulocyte-macrophage colony-stimulating factor (GM-CSF) directly result in apo E down-regulation or indirectly by inducing the secretion of other inflammatory mediators has been investigated. LPS-stimulated macrophages demonstrated a dose-dependent reduction in apo E secretion with a 70% decrease occurring following a 48-h incubation with 20 ng/ml LPS. Coculture of these cells with a neutralizing concentration of a hamster monoclonal antibody against murine tumor necrosis factor (TNF) inhibited the LPS-mediated reduction in apo E secretion. This inhibitory effect resulting from TNF neutralization was not observed using pooled hamster immunoglobulin G, or hamster monoclonals against murine interleukin-1 alpha (IL-1 alpha), IL-1 beta, or interferon-gamma. Similar results were observed when GM-CSF was used to induce apo E down-regulation. The inhibitory effects of TNF neutralization on endotoxin-induced apo E down-regulation were dependent on LPS concentration and were no longer apparent at concentrations greater than 200 ng/ml. These results suggest that an autocrine, TNF-dependent mechanism may play a role in the down-regulation of apo E secretion during macrophage activation.
pericardial effusion, tamponade, atrial collapse, pulmonary artery collapse, inferior vena cava compressionRight atrial and right ventricular collapses are well-known echocardiographic manifestations of large circumcardiac pericardiac effusions with tamponade. Left atrial collapse has been described in tamponade but is less widely known. Compression of the pulmonary trunk (main pulmonary artery) has not yet been reported except as an abstract by one of us (IAD). 1 Compression of the thoracic inferior vena cava has never been reported yet. Figure 1. Left panel: Parasternal long-axis view shows right ventricular collapse (arrow). Right panel: The early diastolic timing of this right ventricular collapse is shown in M-mode. EFF = pericardial effusion; AO = aortic root; LA = left atrium.
Case ReportA 71-year-old man presented with a 1-week history of exertional dyspnea, orthopnea, and a 2-month history of cough and weight loss. He had mild pedal edema, increased jugular venous pressure, and decreased breath sounds over the right lung base. Heart rate 105 beats/min, BP 122/80 mmHg. At this time, a paradoxical pulse of 15 mmHg was noted. Chest X-ray showed a large right pleural effusion and enlarged cardiac silhouette. Computerized tomography of the thorax showed a mass in the superior segment of the right lower lobe and a pericardial effusion. One liter of yellowish fluid was aspirated from the right pleural space; the pleural fluid was exudative.
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