Atypical protease-activated receptor mediates endothelium-dependent relaxation of human coronary arteries

Protease-activated receptors (PARs) are a family of G protein-coupled receptors activated by a tethered ligand sequence within the amino terminal that are revealed by site-specific proteolysis. The thrombin-sensitive PAR-1 and trypsin-activated PAR-2 mediate endothelium-dependent vascular relaxation in a number of species. Because both thrombin and trypsin-like enzymes have been implicated in coronary artery disease, the purpose of this study was to investigate whether similar receptors are present in human coronary arteries. Thrombin (0.001 to 0.1 U/mL) and trypsin (0.001 to 1 U/mL) caused concentration- and endothelium-dependent relaxations of human coronary artery ring segments suspended in organ chambers for isometric tension recording and contracted with the thromboxane A2 mimetic U46619. These relaxations were dependent on the catalytic activity of each enzyme and were inhibited by the NO synthase inhibitor NG-nitro-L-arginine (100 micromol/L) and the NO scavenger oxyhemoglobin (20 micromol/L). The synthetic PAR-1 tethered ligand sequence SFLLRN-NH2 (0.01 to 10 micromol/L) also caused endothelium-dependent relaxation of U46619-contracted human coronary arteries; however, the equivalent PAR-2 ligand SLIGKV-NH2 caused almost no relaxation. In addition, desensitization to either thrombin or trypsin resulted in cross-desensitization to the other enzyme but had only a minimal affect on the response to SFLLRN-NH2. Therefore, we conclude that human coronary artery endothelial cells possess a PAR-1-like receptor that is potently activated by thrombin, trypsin, and SFLLRN-NH2 to cause NO-mediated vascular relaxation. Once cleaved, this receptor is recycled in a truncated form, able to respond to exogenous application of only its tethered ligand sequence, suggesting the presence of another endogenous activator possibly acting independently of receptor cleavage.     

Characterisation of fluid flow through porous media using three-dimensional microimaging and pulsed gradient stimulated echo NMR

Pulsed gradient stimulated echo (PGSTE) and microimaging nuclear magnetic resonance (NMR) are used to probe correlations between structure and flow in the void space of a model porous system formed from a packing of 1-mm diameter glass spheres. The pulsed gradient stimulated echo data determine the average propagator and permit the dispersion of the flow to be studied as a function of delay time. Microimaging yields structural information and, specifically, a reduced radial distribution function (rdf) for the structure of the void space. Transition to fully developed dispersive flow is shown to occur on a scale size for which no further correlations in the structure of the void space are observed.     

Angiomyofibroblastoma of the vulva and vagina

Nine vulvar and three vaginal angiomyofibroblastomas from patients 23 to 71 years of age (mean, 46 yr) were analyzed. The tumors were well circumscribed and ranged from 0.9 to 11 cm (average, 4.7 cm) in maximal dimension. On microscopic examination, they had hypercellular and hypocellular areas. The neoplastic cells were spindle-shaped, plasmacytoid, or epithelioid; a variable number were binucleated or multinucleated cells. A focal storiform pattern was present in one tumor, and, in one tumor, the neoplastic cells formed a collar around a central area of dense collagen. There was no significant nuclear atypia, and there was less than one mitotic figure per 10 high-power fields. The tumors contained small- to medium-sized blood vessels, which were characteristically thin walled and, occasionally, ectatic and branching. The stroma was edematous, separated collagen fibers and contained a variable number of inflammatory cells, especially lymphocytes and mast cells. Three vulvar tumors contained a variable amount of fat. Ultrastructural study of three tumors showed intracytoplasmic, dilated, rough endoplasmic reticulum, moderate numbers of pinocytotic vesicles, and numerous filaments without dense bodies; rare intercellular rudimentary junctions were identified. Eleven of 11 tumors were immunoreactive for vimentin, 11 of 12 for desmin, three of 11 for muscle actin, one of 12 for smooth muscle actin, and four of 12 for CD34. There was no staining for factor XIIIa, keratin, S100 protein, Leu-7, glial fibrillary acidic protein, or CD68. Follow-up revealed no recurrences or metastases. Angiomyofibroblastoma is a distinctive benign tumor that arises most commonly in the vulva and vagina and has a diverse histologic and immunohistochemical profile.