Background-Shed membrane microparticles circulate in the peripheral blood of nonischemic (NI) patients and patients with myocardial infarction (MI). We investigated whether or not these microparticles would affect endotheliumdependent responses. Methods and Results-Rat aortic rings with endothelium were exposed for 24 hours to circulating microparticles isolated from 7 patients with NI syndromes and 19 patients with acute MI. Endothelium-dependent relaxations to acetylcholine were not affected by high concentrations of microparticles from NI patients (Pϭ0.80). However, significant impairment was observed in preparations exposed to microparticles from patients with MI at low and high concentrations, corresponding to 0.7-fold and 2-fold circulating plasma levels (Pϭ0.05 and 0.001, respectively). Impairment was not affected by diclofenac (Pϭ0.47), nor by the cell-permeable superoxide dismutase mimetic Mn(III)tetra(4-benzoic acid) porphyrin chloride (Pϭ0.33), but it was abolished by endothelium removal or by N monomethyl-L-arginine. Relaxations to the calcium ionophore ionomycin were decreased in rings exposed to microparticles from MI patients (Pϭ0.05 and 0.009 for low and high concentrations, respectively), but microparticles from NI patients had no effect (Pϭ0.81). Finally, high concentrations of microparticles from MI patients affected neither endothelium-independent relaxation to sodium nitroprusside (Pϭ0.59) nor expression of the endothelial nitric oxide synthase (Pϭ0.43). Key Words: endothelium-derived factors Ⅲ nitric oxide synthase Ⅲ arteries Ⅲ vasodilation Ⅲ myocardial infarction M icroparticles generated in vitro from activated platelets or leukocytes stimulate cultured endothelial cells to produce prostacyclin and cytokines and to express adhesion molecules. [1][2][3][4] Recently, apoptotic microparticles have been identified in the circulating blood of patients with acute coronary syndromes and in nonischemic (NI) patients. 5 Acute myocardial infarction (MI) is associated with substantial impairment of vasodilator function in both infarcted myocardium and myocardium perfused by normal vessels. The determinants of this vasomotor dysfunction that may contribute to the extent of ischemia and necrosis after coronary occlusion are not fully elucidated. 6 In the present study, we examined whether or not microparticles circulating in the peripheral blood of NI patients and patients with acute MI affect endothelium-dependent responses in a normal blood vessels. Conclusions-Circulating Methods Patient SelectionWe prospectively included 19 patients with acute MI and 7 NI patients. Patients with MI had clinical, electrocardiographic, and enzymatic changes that were diagnostic of acute MI and were subsequently documented as having significant coronary atherosclerosis by angiography (Table). Control NI patients consisted of 4 patients recruited from the same cardiology department and 3 healthy subjects. Because relaxations did not differ among them (Pϭ0.35), these 7 subjects were pooled into one control NI group (me...

The retinoblastoma protein (pRB) is encoded by the RB1 gene whose promoter contains several putative binding sites for ICBP90 (Inverted CCAAT box Binding Protein of 90 kDa), a transcriptional regulator of the topoisomerase IIalpha gene. ICBP90 has two consensus binding sites for pRB in its primary sequence. Here, we show that pRB and ICBP90 co-immunoprecipitate in cell extracts of proliferating human lung fibroblasts and of proliferating or confluent Jurkat cells. GST pull-down assays and immunocytochemistry, after cell synchronization in late G1 phase, confirmed this interaction. Overexpression of ICBP90 induces downregulation of pRB expression in lung fibroblasts as a result of mRNA decrease. DNA chromatin immunoprecipitation experiment shows that ICBP90 binds to the RB1 gene promoter under its methylated status. Overexpression of ICBP90 increases the S and G2/M phase cell fractions of serum-starved lung fibroblasts as assessed by flow cytometry analysis and increases topoisomerase IIalpha expression. Together, these results show that ICBP90 regulates pRB at the protein and gene transcription levels, thus favoring the entry into the S phase of the cells. We propose that ICBP90 overexpression, found in cancer cells, is involved in the altered checkpoint controls occurring in cancerogenesis.

Our data suggest that in a selected population of patients with severe septic shock single plasma cortisol determination has no predictive value. The short ACTH stimulation test performed within the first 24 h of onset shock can neither predict outcome nor estimate impairment in adrenocortical function in patients with high basal cortisol level. Adrenal insufficiency is rare in septic shock and should be suspected when cortisol level is below 15 micrograms/dl and then confirmed by a peak cortisol level lower than 18 micrograms/dl during the short ACTH stimulation test.

Flow-dependent dilation is a fundamental mechanism by which large arteries ensure appropriate blood supply to tissues. We investigated whether or not the vascular kallikrein-kinin system, especially tissue kallikrein (TK), contributes to flow-dependent dilation by comparing wild-type and TK-knockout mice in which the presence or absence of TK expression was verified. We examined in vitro changes in the outer diameter of perfused carotid arteries from TK / and TK / mice. In both groups, exogenous bradykinin caused a similar dilation that was abolished by the B 2 receptor antagonist HOE-140, as well as by the NO synthase inhibitor N-nitro-L-arginine methyl ester. However, purified kininogen dilated only TK / arteries, demonstrating the essential role of TK in the vascular formation of kinins. In TK / arteries, increasing intraluminal flow caused a larger endothelium-dependent dilation than that seen in TK /. In both strains the flow response was mediated by NO and by endothelium-derived hyperpolarizing factor, whereas in TK / vasoconstrictor prostanoids participated as well. HOE-140 impaired flow-dependent dilation in TK / arteries while showing no effect in TK /. This compound reduced the flow response in TK / arteries to a level similar to that in TK /. After NO synthase inhibition, HOE-140 no longer affected the response of TK /. Impaired flow-dependent dilation was also observed in arteries from knockout mice lacking bradykinin B 2 receptors as compared with wild-type animals. This study demonstrates the active contribution of the vascular kallikrein-kinin system to one-third of the flow-dependent dilation response via activation of B 2 receptors coupled to endothelial NO release. (Circ Res. 2001;88: 593-599.) Key Words: bradykinin kininogen flow-dependent vasodilation endothelium bradykinin B 2 receptor L arge arteries accommodate changes in blood flow by increasing their diameter via the release of endothelial factors such as NO, prostacyclin, and endothelium-derived hyperpolarizing factor (EDHF). 1-4 This flow-dependent dila-tion (FDD) response represents a fundamental physiological mechanism that acts to oppose vasoconstriction, normalize shear stress, and ensure appropriate blood supply to tissues. Bradykinin modulates vascular smooth muscle tone by stimulating endothelial B 2 receptors and releasing NO and other mediators. 5-7 Bradykinin is a product of the cleavage of high and low molecular weight kininogens resulting from activation of proteases such as plasma and tissue kallikreins (TKs), cathepsins, or calpains. 8-12 The presence in the vessel wall of kininogens and kallikrein-like activities, including TK, suggests the existence of an endogenous vascular kinin-generating system, different from the circulating plasma kallikrein-kinin system. 13-16 However, the physiological role of the vascular kallikrein-kinin system itself has not been fully established because of the possible contribution of preadsorbed plasma kallikrein to vascular kinin formation and the lack of specific inhibitors of TK. 17-19 ...