Abstract-A decline in oxygen concentration perturbs endothelial function, which promotes local thrombosis. In this study, we determined whether hypoxia in the range of that observed in pathophysiological hypoxic states stimulates plasminogen activator inhibitor-1 (PAI-1) production in bovine aortic endothelial cells. PAI-1 production, measured by ELISA, was increased by 4.7-fold (PϽ0.05 versus normoxic control, nϭ4) at 12 hours after hypoxic stimulation. Northern blot analysis showed the progressive time-dependent increase in the steady-state level of PAI-1 mRNA expression by hypoxia, which reached a 7.5-fold increase (PϽ0.05 versus control, nϭ4) at 12 hours. Deferoxamine, which has been known to bind heme protein and to reproduce the hypoxic response, induced PAI-1 production at both the mRNA and protein levels. The half-life of PAI-1 mRNA, as determined by a standard decay assay, was not affected by hypoxia, suggesting that induction of PAI-1 mRNA was regulated mainly at the transcriptional level. Transient transfection assays of the human PAI-1 promoter-luciferase construct indicates that a hypoxia-responsive region lies between Ϫ414 and Ϫ107 relative to the transcription start site, where no putative hypoxia response element is found. The hypoxia-mediated increase in PAI-1 mRNA levels was attenuated by the tyrosine kinase inhibitors genistein (50 mol/L) and herbimycin A (1 mol/L), whereas PD98059 (50 mol/L, MEK1 inhibitor), SB203580 (10 mol/L, p38 mitogen-activated protein kinase inhibitor), and calphostin C (1 mol/L, protein kinase C inhibitor) had no effect on the induction of PAI-1 expression by hypoxia and deferoxamine. Genistein but not daidzein blocked the production of hypoxia-and deferoxamine-induced PAI-1 protein. Thus, we conclude that hypoxia stimulates PAI-1 gene transcription and protein production through a signaling pathway involving genistein-sensitive tyrosine kinases in vascular endothelial cells. Key Words: hypoxia Ⅲ PAI-1 Ⅲ tyrosine kinase Ⅲ mitogen-activated protein kinase Ⅲ endothelial cells T here is growing evidence indicating that vascular endothelium plays an obligatory role in regulating fibrinolytic activity, such as vascular tone and platelet activity. 1 Endothelial dysfunction leads to the derangement of vascular endothelial anticoagulant properties and contributes to the pathophysiology of several cardiovascular disorders, including intravascular thrombosis, intimal growth, and plaque rupture. 2 Endothelial cells have been shown to produce many vasoactive substances that intervene in the fibrinolysis and coagulation processes. Of the many components regulating the balance between procoagulant and anticoagulant properties of the endothelium, pathways controlling plasminogen activator activity are particularly important. This activity is controlled primarily by plasminogen activator inhibitor-1 (PAI-1), which is synthesized by endothelial cells, 3 smooth muscle cells, 4,5 platelets, 6 monocytes, 7 and hepatocytes. 8

BackgroundInfective endocarditis due to Escherichia coli is a rare disease but is increasing in frequency, especially among older women. In addition, its mortality rate is higher than that of endocarditis due to the HACEK-group gram-negative bacteria (Haemophilus spp., Aggregatibacter spp., Cardiobacterium hominis, Eikenella corrodens, and Kingela spp.).Case presentationA 58-year-old Japanese woman with a history of alcohol abuse was admitted to our hospital because of a fever. She was diagnosed with infective endocarditis due to E. coli based on repeated blood cultures and transthoracic echocardiography, which revealed vegetations attached to the anterior leaflet and chordae tendineae of the mitral valve. Despite administration of sulbactam/ampicillin and gentamycin, she developed purulent spondylitis during hospitalization and required treatment with meropenem administration for 6 weeks, leading to resolution of the endocarditis. She took oral levofloxacin for 2 months, and the spondylitis was completely cured 7 months after discharge.ConclusionEscherichia coli affects native valves without degenerative valvulopathy rather than prosthetic valves, especially in patients with risk factors such as an immunosuppressive status, excessive alcohol consumption, or treatment with hemodialysis. Peripheral embolization, congestive heart failure, and valve-ring abscesses are major complications of E. coli endocarditis; notably, infective myocarditis can also occur. The mortality and surgical intervention rates are 21% and 42%, respectively. Physicians should be cognizant of the necessity of surgical intervention when E. coli endocarditis is resistant to antibiotic therapy.