Yields of y-resorcylic acid afforded by various modifications of the Kolbe-Schmitt reaction have been explored and methods of separating the acid from the accompanying @-isomer have been studied. Selective elution of the acids from a column of an anion-exchange resin in the chloride form with solutions of hydrochloric acid in water or aqueous alcohol effects complete separation.A process for the partial conversion of Pinto y-resorcylic acid is reported.
Twenty-one pairs of parallel assays of corticotrophin are reported, in which results from hypophysectomized rats are compared with those from hydrocortisone-treated animals. The two methods show little difference in respect of potency, precision and limits of error.The most widely used method for the biological assay of corticotrophin is that developed by Sayers, Sayers & Woodbury (1948), which measures the depletion of adrenal ascorbic acid in hypophysectomized rats. The procedure involves severe operational stresses and much skill, hypophysectomy being followed one day later by removal of one adrenal gland before injection of corticotrophin, to serve as a control, and removal of the remaining adrenal gland exactly 1 hr after injection. The difference in the ascorbic acid concentration in the two adrenal glands forms the criterion of response.The first attempt to simplify this procedure was that of Munson, Barry & Koch (1948), in which the first adrenalectomy was omitted and both adrenals were removed after injection of corticotrophin and analysed together for ascorbic acid, the ascorbic acid concentration being inversely related to the dose of corticotrophin. This method still left some operational stress and the need for skill in hypophysectomy. Many attempts were made to avoid this operation by blocking the secretion of endogenous corticotrophin. After the original suggestion by Sayers & Sayers (1947) that certain corticosteroids, including cortisone, hydrocortisone (cortisol) and deoxycortone, blocked the secretion of corticotrophin, Hodges & Vernikos (1958) found that prednisolone and hydrocortisone (cortisol) were most effective in this respect. Dekanski & Harvie (1960) gave the results of forty assays in which hypophysectomy was replaced by injection of hydrocortisone acetate, and claimed the procedure to be one-and-a-half to two times as efficient as the original method, but they gave no results of assays on the same sample by both methods. Hamburger (1960) found all corticosteroids and their synthetic analogues to be inhibitory, with inhibition increasing in the order cortisone, hydrocortisone, prednisolone trimethyl acetate, prednisolone and dexamethasone. The last two gave complete inhibition in doses of 1.5 and 1.0 mg respectively per 100 g of rat body weight. Casentini, Hukovic & Tani (1957) found that fludrocortisone (0.9 mg per 100 g of rat body weight) completely inhibited the secretion of corticotrophin. Hamburger (1960) D
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