Differential expression and release of CD54 induced by cytokines.

Intercellular adhesion molecule-1 (ICAM-1, CD54) is upregulated in many cell types stimulated by cytokines. A human hepatoblastoma cell line (C3A, a subclone of HepG2/C3 that is currently being used as a surrogate liver) and human lung adenocarcinoma cells (A549) were stimulated with interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN gamma), or IL-6 to determine any differences in cell type responsiveness to individual cytokines for ICAM-1 upregulation. Time courses were performed with each cytokine evaluating ICAM-1 mRNA, surface expression, and cICAM-1 in the cell culture media. Between 3 and 6 hours, IL-1 beta (30 U/mL) stimulated the greatest increase in hepatocyte ICAM-1 mRNA, followed by IFN gamma (100 U/ mL), and IL-6 (100 U/mL) in order of potency. Except for IL-6, cytokine-induced hepatocyte surface levels of ICAM-1 (immunofluorescence flow cytometry, mAb R6.5) were dose dependent, with inhibition at higher concentration. Highest levels followed stimulation with INF gamma (P < .05). Significantly less was found after both IL-1 beta and TNF alpha; none was detected after IL-6 (P < .05). In contrast, IL-1 beta stimulated significantly more cICAM-1 release from hepatocytes than the other cytokines (P < .001), and IL-6 stimulated modest cICAM-1. Between 3 and 6 hours in the A549 cells, IL-1 beta stimulated the greatest increase in ICAM-1 mRNA, followed by TNF alpha. Both responses were greater than that observed in the hepatocytes. IFN gamma- and IL-6-induced ICAM-1 mRNA synthesis was not different from unstimulated A549 cells. Cytokine-induced A549 surface levels of ICAM-1 (immunofluorescence flow cytometry, mAb R6.5) was highest for IL-1 beta (peak levels similar to hepatocyte response), modest with TNF alpha (peak levels less than hepatocytes), detectable with IFN gamma (much less than hepatocytes), and nondetectable after IL-6. No ICAM-1 release from A549 cells was induced under any condition. In hepatocytes the amount of ICAM-1 mRNA was best accounted for by considering both cell surface levels of ICAM-1 and cICAM-1 levels. In human lung adenocarcinoma cells, the cytokine induction of ICAM-1 mRNA could potentially be accounted for by observing cell surface levels of ICAM-1 because no cICAM-1 was produced. These results suggest that surface ICAM-1 and cICAM-1 may be differentially controlled by each cytokine and by each parenchymal cell type.

Myocardial contrast echocardiography: relation of collateral perfusion to extent of injury and severity of contractile dysfunction in a canine model of coronary thrombosis and reperfusion.

OBJECTIVES: This study sought to determine whether myocardial contrast echocardiography could be used to detect and quantitate collateral blood flow capable of limiting the effects of ischemia in an experimental model of coronary thrombosis and reperfusion. BACKGROUND: Myocardial contrast echocardiography has been used to assess collateral blood flow in humans, but this technique has not been extensively validated in the experimental laboratory. METHODS: Myocardial ischemia occurred after electrically induced left circumflex coronary artery thrombosis in a canine model. Ischemia was intensified by administration of vasodilators. Reperfusion was induced with recombinant tissue-type plasminogen activator. Myocardial perfusion was assessed with contrast echocardiography and radiolabeled microspheres. Infarct size was determined by histochemical staining methods. Myocardial samples were evaluated histologically. RESULTS: The dogs were classified into two groups on the basis of contrast echocardiographic detection of perfusion in the ischemic region: those with (n = 13) and without collateral flow (n = 10). Collateral perfusion detected by contrast echocardiography paralleled changes detected by radiolabeled microspheres during thrombosis and vasodilator administration. A 91% agreement was observed between the two techniques in detecting collateral flow > 0.3 ml/min per g (p < 0.0001). Collateral perfusion correlated directly with radial shortening fractions of the ischemic myocardium (p < 0.01). Recovery of function after reperfusion was faster, infarct size was smaller (mean [+/- SD] 4 +/- 1% vs. 11 +/- 3%, p = 0.05), and histopathologic injury was less in dogs with than without collateral flow, respectively (p < 0.05). CONCLUSIONS: Myocardial contrast echocardiography can identify physiologically significant collateral vessels capable of limiting the degree of ischemic damage during coronary thrombosis. The magnitude of collateral flow and the change in flow induced by vasodilators can be assessed and compares favorably with the microsphere standard.

Myocardial contrast echocardiography: relation between on-line and off-line assessment of myocardial perfusion.

BACKGROUND: Quantitative assessment of myocardial perfusion by myocardial contrast echocardiography has been made possible by the use of custom-made off-line video-intensity programs. A standardized program that could be used by all investigators would improve the reproducibility of results and enhance its clinical utility. METHODS AND RESULTS: The purpose of this study was to determine if the assessment of myocardial perfusion by contrast echocardiography using a new commercially available, quantitative on-line software program correlates with an off-line custom-made video-intensity program previously validated by our laboratory and with radiolabeled microspheres, under various experimental myocardial perfusion conditions. Two of the measured myocardial contrast echocardiographic parameters (peak intensity, area under the time-intensity curve {area}) correlated well among on-line and off-line methods and radiolabeled microspheres, especially when the data were "normalized" by comparing percent change from baseline or a ratio of ischemic to nonischemic myocardium. The third myocardial contrast echocardiographic parameter examined, half-time of the peak intensity on the washout limb of the curve (t 1/2), correlated only when the percent change from baseline was compared between the two methods or when the off-line method was compared with radiolabeled microspheres. CONCLUSION: The results of this investigation add further support to the potential use of myocardial contrast echocardiography to evaluate serial changes in myocardial perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler quantification of echo-contrast injections in vivo.

It is difficult to quantify myocardial perfusion using contrast echocardiography because the echogenicity of injected contrast is unknown. We propose that a measurement of Doppler amplitude from blood in a systemic artery during the passage of contrast could define the needed input function. Time-amplitude curves from pulsed Doppler cuffs on coronary and carotid arteries of 7 dogs were analyzed during aortic root and left atrial injections of Albunex. We found in individual animals that the areas under the Doppler time-amplitude curves were correlated to the amount of Albunex injected (R = 0.87-0.99), inversely correlated to cardiac output (R = 0.83), and uncorrelated to coronary flow (R = 0.18). Due to better mixing, the coronary and carotid response areas correlated better for left atrial injections (R = 0.96) than for aortic root injections (R = 0.56). We conclude that Doppler amplitude detection can be used to quantify the passage of echo-contrast agents, that the measurements comply with indicator-dilution principles, and that systemic measurements in the carotid artery could be used to predict the coronary input function for injection sites with good systemic mixing.

An alpha-adrenergic coronary constriction during esophageal distention in the dog.

Previous work has shown an increase in sympathetic stimulation of the heart during chemical or mechanical irritation of visceral organs, but the involvement of the coronary circulation in such reflexes is not clear. In five preliminary experiments in anesthetized dogs, esophageal distention produced a sympathetic stimulation of the heart, as evidenced by an increase in heart rate, which was abolished by non-selective beta-adrenergic and muscarinic blockades. On the basis of these preliminary data, we further examined a sympathetic coronary constriction during acute esophageal distension in which any direct adrenergic coronary constriction was unmasked by muscarinic blockade with atropine (100 micrograms/kg, i.v.), and non-selective beta-adrenergic blockade with propranolol (1 mg/kg, i.v.). In seven dogs anesthetized with alpha-chloralose in an open-chest procedure, the esophagus was rapidly distended to a pressure of 36 +/- 2 mm Hg, which was not significantly different from the distending pressure used in the preliminary experiments. During esophageal distention, the mean circumflex blood flow decreased to 77 +/- 10% (SEM) of the predistention value. This decrease was statistically significant (p less than 0.05). There was no change in left ventricular pressure, mean arterial pressure dP/dtmax, or heart rate. Intracoronary administration of the nonselective alpha-adrenergic antagonist phentolamine completely abolished the reduction in mean circumflex coronary blood flow caused by esophageal distention in the presence of beta-adrenergic and muscarinic blockades. These results demonstrate a direct sympathetic coronary vasoconstriction elicited by esophageal distention. This vasoconstriction was due to activation of coronary alpha-adrenergic receptors.