Endothelin releases prostacyclin and thromboxane A2 from guinea pig or rat isolated lungs and endothelium-derived relaxing factor in the perfused mesentery of the rat. Endothelin is also substantially removed by the pulmonary circulation of the rat in vitro and in vivo and by guinea pig lungs in vitro. In the rat, the effects of endothelin on the blood pressure vary from pressor (in pithed rats) to purely depressor in anesthetized rats where the resting blood pressure is high. It therefore 4ias the characteristics of a local pressor hormone, rather than a circulating one.The endothelial cell (EC) is known to release vasoactive substances such as prostacyclin (PGI2) (1) and endotheliumderived relaxing factor (EDRF) (2), recently identified as nitric oxide (3). Release of endothelium-dependent vasoconstrictor factors has been observed in response to various chemical and physical stimuli such as norepinephrine (4), thrombin (4), hypoxia (5, 6), increased transmural pressure (7), and mechanical stretch (8).Masaki and his colleagues (9) have recently characterized from cultures of porcine aortic ECs a 21-amino acid peptide, which they called endothelin (ET). In the chemically denervated rat, porcine ET is the most potent pressor substance yet described, with a long duration of action. They suggested that ET directly activates dihydropyridine-sensitive calcium channels.We report here that apart from its vasoconstrictor activity, ET can release potent vasodilator substances such as PGI2 and EDRF and is also removed by the pulmonary circulation.MATERIALS AND METHODS Superfusion Bioassay. Spiral strips of de-endothelialized vascular smooth muscle from the rabbit (mesenteric artery, celiac artery, carotid artery, aorta, jugular vein, mesenteric vein) and other smooth muscle preparations (guinea pig trachea, guinea pig ileum, rat stomach strip, rabbit duodenum) were mounted in a cascade (10) and superfused at 5 ml-min-1 with Krebs-Ringer solution containing indomethacin (5.6 ,M). Agonists such as ET (1-50 pmol), bradykinin(1-10 pmol), substance P (1-10 pmol), and angiotensin 11 (1-10 pmol) were injected over the assay tissues.Isolated Lungs. Male Dunkin-Hartley guinea pigs (300-400 g) or male Wistar rats (200-300 g) were anesthetized with sodium pentobarbital (Sagatal, 70 ,umol kg-', i.v.) and a thoracotomy was performed. The pulmonary artery and the trachea were cannulated and the lungs were removed and placed in a warm chamber. The lungs were perfused at S ml-min-' via the pulmonary artery with oxygenated (95% 02/ 5% CO2) and warmed (370C) Krebs-Ringer solution (11). The lungs were left to stabilize for 30 min and ET was infused for 3 min at a flow rate of 0.1 ml-min-' to achieve a final concentration of 1 or 10 nM. The effluent from lungs was collected and analyzed by RIA for 6-oxoprostaglandin F1l (6-oxo-PGF1,) and thromboxane (TX) B2 as measures of prostacyclin and TXA2 release (12). The removal of ET was calculated by comparing the contractions of the assay tissues in response to infusions of ET directly over...

One hundred and forty-seven mothers were screened for major depression at six to eight weeks post-partum. Using predetermined cut-off points, the Edinburgh Postnatal Depression Scale and the Beck scale were compared in their abilities to identify the 15% of subjects who had major depression according to DSM-III criteria. The sensitivity of Edinburgh scale was 95% and its specificity 93%. The performance of the Beck scale was markedly inferior, with a sensitivity of 68% and specificity of 88%.

A study of autoimmune related phenomena in 350 women with histologically confirmed lichen sclerosus et atrophicus revealed that 21.5% had one or more autoimmune related diseases, 21% had one or more first degree relatives with an autoimmune-related disease, 42% had an autoantibody at a titre greater than 1:20, and 59.5% had one or more of these autoimmune-related phenomena. No statistically significant differences in the natural history of lichen sclerosus et atrophicus were demonstrated between those patients with autoimmune-related phenomena and those without.

A strain of the gas-vacuolate cyanobacterium Microcystis was found to float in cultures grown at low light intensities and to sink in those grown at high intensities. The loss of buoyancy that occurred within 1 to 5 h on increasing the photon flux density from 10 to 100 pmol m-2 s-' was investigated by centrifuging the cell suspensions in a horizontally placed capillary with a rectangular cross-section, and then separately counting the floating cells under the upper tube surface and sinking cells on the lower surface. Buoyancy loss was not accompanied by loss of gas vesicles, as occurs in some other planktonic cyanobacteria, but was caused by a relative increase in dry matter, principally carbohydrate, without a corresponding increase in gas vesicles. The increase in light intensity gave an increase in cell turgor pressure but this was insufficient to collapse the strong gas vesicles present in this strain, which had a median critical pressure of 0.75 MPa (7.5 bar).