1 OPC-31260, a benzazepine derivative, has been studied for its ability to antagonize the binding of arginine vasopressin (AVP) to receptors in rat liver (V1) and kidney (V2) plasma membranes, for antagonism of the antidiuretic action of AVP in alcohol-anaesthetized rats and for diuretic action in conscious normal rats. 2 OPC-31260 caused a competitive displacement of [3H]-AVP binding to both V1 and V2 receptors with IC50 values of 1.2 + 0.2 x 106M and 1.4 + 0.2 x 10-8M, respectively. 3 OPC-31260 at doses of 10 to 100pg kg-', i.v., inhibited the antidiuretic action of exogenously administered AVP in water-loaded, alcohol-anaesthetized rats in a dose-dependent manner. OPC-31260 did not exert an antidiuretic activity suggesting that it is not a partial V2 receptor agonist. 4 After oral administration at doses of 1 to 30mgkg-1 in normal conscious rats, OPC-31260 dosedependently increased urine flow and decreased urine osmolality. The diuretic action of OPC-31260 was characterized as aquaresis, the mode of diuretic action being different from previously known diuretic agents such as furosemide, hydrochlorothiazide and spironolactone. 5 The results indicate that OPC-31260 is a selective V2 receptor antagonist and behaves as an aquaretic agent. OPC-31260 will be a useful tool in studying the physiological role of AVP and in the treatment of various conditions characterized by water retention.

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Asymmetric redox C-C bond formation between alpha-alkyl-alpha-diazocarbonyl compounds and aldehydes was developed as a practical and general method for the construction of alpha-alkyl-beta-keto imides having a chiral nonracemic tertiary stereogenic center.

Four species of the genus Platorchestia Bousfield are described from Taiwan, e.g., P. pacifica n. sp., P. joi Stock and Biembaum, 1994, P. japonica (Tattersall,l922) and P. humicola (Martens, 1868). The former two species, together with P. platensis (Kmyer, 1845) and P. munmui Jo, 1988, compose a closely related species cluster. P. pacifica n. sp. was found on almost all the coast of the mainland and neighboring islands in Taiwan, while the other three species were found in the mainland north of23.5°N.