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1. Polymorphonuclear neutrophils are involved in the development of myocardial injury during ischaemia through the release of free oxygen radicals and by adhesion of activated polymorphonuclear neutrophils to endothelium, resulting in plugging of coronary capillaries. Polymorphonuclear neutrophil activation may be a result of contact with ligands expressed by endothelial cells and/or a response to soluble stimuli released from ischaemic tissue to the plasma. 2. To investigate this we studied plasma-mediated polymorphonuclear neutrophil activation in vitro using plasma samples collected from 14 patients with acute myocardial infarction at time of admission and 6 h and 1, 2, 5 and 7 days later. Plasma samples were incubated with washed polymorphonuclear neutrophils isolated from healthy donors. Expression of adhesion molecules CD18/CD11b integrin and L-selectin (Leu-8) were measured by flow cytometry and superoxide anion production in polymorphonuclear neutrophils was measured by chemiluminescence. 3. Plasma samples obtained 6 h and 1 day after admission were capable of inducing CD18/CD11b antigen expression, superoxide anion production and L-selectin shedding in the washed polymorphonuclear neutrophils, and this effect was significant when compared with plasma taken at 5 and 7 days after admission. 4. The plasma-mediated polymorphonuclear neutrophil stimulation was prevented when the PMN were pretreated with platelet-activating factor receptor antagonists BN52021 or BN50739. The platelet-activating factor concentrations detected in the plasma samples were not higher than those detected in plasma from healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Tyrphostins are a group of low molecular weight synthetic inhibitors of protein tyrosine kinases (PTK). The intracellular domains of the receptors for epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), insulin-like growth factor 1 (IGF-1) possess PTK activity. Since EGF, TGF-alpha and IGF-1 are considered to play an important role in the proliferation of pancreatic cancer cells, we studied the effects of tyrphostins on the growth of three human pancreatic cancer cell lines (MiaPaCa-2, Panc-1 and CAV). The tyrphostins AG17, T23 and T47 all inhibited EGF and serum-stimulated DNA synthesis. AG17 was found to be the most potent of these agents and caused a dose-dependent but reversible inhibition of cell growth. Furthermore using an immunoblotting procedure we also found AG17 to inhibit EGF-induced tyrosine phosphorylation in the MiaPaCa-2 cell line. Tyrosine kinase inhibitors may prove to be useful agents for the treatment of pancreatic cancer. Images Figure 7

Myocardial ischemia leads to the activation of neutrophils as well as endothelial cells. The interaction between these cells is dependent on certain adhesion glycoproteins which are expressed on their surface. Adhesion of neutrophils to endothelium, mediated by adhesion molecules, has been shown to result in coronary capillary plugging and impairment of coronary blood flow. In certain conditions, upon cell activation, adhesion proteins may be released in soluble form into the circulating blood. The purpose of our study was to verify whether myocardial ischemia occurring during angina episodes results in the release of the soluble adhesion molecules, L-selectin, E-selectin, and intracellular adhesion molecule-1 (ICAM-1), into the circulation. Plasma samples were collected by venepuncture from 15 patients admitted to the emergency room with chest pain caused by attacks of angina pectoris and 15 patients with noncardiac chest pain. To confirm the diagnosis, all patients underwent an exercise stress test and, if not conclusive, 99mTc MIBI SPECT or coronary arteriography. Another set of plasma samples were taken from each patient in the absence of chest pain. In addition, blood for analysis was obtained from 15 sex-and age-matched healthy subjects. Soluble adhesion molecules plasma levels were measured by standard enzyme-linked immunosorbent assay. In patients with angina pectoris, plasma levels of soluble L-selectin estimated during chest pain were significantly higher than in the control group and decreased in the absence of chest pain. Similarly, the mean concentration of soluble ICAM-1 at the time of angina onset was significantly elevated in the patients in comparison with the control group and remained higher, although not significantly, in the absence of chest pain. In patients with noncardiac chest pain, plasma levels of soluble L-selectin did not differ significantly from those observed in control subjects. In this group of patients, the plasma levels of soluble ICAM-1 estimated during pain onset and in the absence of this symptom were not significantly elevated. On the contrary, the mean values of soluble E-selectin in the patients with ischemic cardiac pain during chest pain and in the absence of this symptom, as well as those in the patients with noncardiac chest pain during or without symptoms, remained unchanged in comparison with the control group. During attacks of angina pectoris an increase in the plasma levels of the soluble adhesion molecules, ICAM-1 and L-selectin, was noted, possibly reflecting activation of neutrophils and endothelial cells during myocardial ischemia. However, E-selectin plasma levels remained unchanged in response to myocardial ischemia.