H. B. Van Dyke

Amino acids in posterior pituitary protein.

Abstract Posterior pituitary protein is composed of 16 amino acids. These have been determined after acid hydrolysis by means of paper chromatography. The results have been compared with those of du Vigneaud, Pierce, and Turner, who analyzed the oxytocic and vasopressor polypeptides of the posterior pituitary.

Antidiuretic hormone in the urine and pituitary of the kangaroo rat.

Summary The kangaroo rat (Dipodomys merriami) excretes large amounts of antidiuretic hormone in the urine (up to 50 milli-units per ml). The presence of this high concentration of hormone is believed to be related to the ability of this desert rodent to excrete the most concentrated urine of any mammal and to reflect a correspondingly high rate of secretion of antidiuretic hormone by the posterior pituitary. In 2 other mammals, the dog with powerful osmotic stimulation of the cerebrum, and the laboratory rat (Long-Evans strain) deprived of water for 48-72 hours, the maximum concentration of hormone in the urine is about 6 m.u. per ml. The hormone in kangaroo-rat urine undergoes sedimentation in the ultracentrifuge and thus resembles endogenous antidiuretic hormone in canine urine. The pituitary of kangaroo rats contains more antidiuretic hormone than that of normal laboratory rats although the latter are 5 to 6 times larger. After 72 hours of thirst the laboratory rats pituitary contains an increased amount of hormone. Each microgram of fresh posterior lobe contains about 0.9 m.u. of antidiuretic hormone in kangaroo rats and about 0.3 m.u. in normal laboratory rats.

Evidence for the presence of arginine vasotocin (8-arginine oxytocin) and oxytocin in neurohypophyseal extracts from amphibians and reptiles.

Abstract Neurohypophyseal extracts from frogs ( Rana catesbeiana ), toads ( Bufo americanus ), green turtles ( Chelonia mydas ), and caimans ( Caiman crocodilus ) have been studied. These extracts have been assayed on a variety of biological preparations. The patterns of pharmacological activities found indicate that they all contain arginine vasotocin (8-arginine oxytocin). This peptide has been demonstrated previously in birds and teleost fishes. It is quite possibly present in the neurohypophyses of all nonmammalian vertebrates except elasmobranchs. Pharmacological evidence indicates that oxytocin is present also in frog, toad, and turtle extracts.

Amyloidosis in Hamsters with Leishmaniasis.

Summary Forty-six days after successful inoculation of L. donovani into hamsters, there appeared edema associated with amyloidosis. There was marked anasarca at 60 and 77 days after infection with extensive deposition of amyloid in the glomeruli and the adrenal cortex. The hypoalbuminemia, which coincided with the edema and a proteinuria, is believed to have been caused by the impairment of glomerular function.

Comparison of Pharmacological Effects of Lysine and Arginine Vasopressins.

Summary 1. Ihe pharmacological effects of lysine and arginine vasopressins are the same with respect to their relative vasopressor, milk-ejecting and avian depressor potencies. 2. The ratio of pressor potency to antidiuretic potency is 1 for arginine vasopressin and 6 for lysine vasopressin when the antidiuretic potency is determined by intravenous injection in the hydrated, unanesthetized dog. On the other hand, this ratio of potencies is 1 for both vasopressins when the antidiuretic potency is determined by subcutaneous injection in the hydrated, unanesthetized rat. 3. Lysine vasopressin, compared with the U.S.P. standard or arginine vasopressin, is equally potent as an intravenous pressor agent in the dog and rat. Potency refers to relative potency; potency in units per mg is much higher for purified arginine vasopressin. 4. Lysine vasopressin is peculiar to the hog. The vasopressin of man, the macaque monkey, dog, rat, ox, sheep and camel appears, by pharmacological criteria, to be arginine vasopressin. These conclusions are tentative and must be confirmed by the isolation of the hormone from each species, other than the ox and hog, together with the demonstration of the amino acid composition of each vasopressin.

Thioglycollate inactivation of posterior pituitary antidiuretic principle as determined in the rat.

Summary and Conclusions After intraperitoneal or subcutaneous injection, an aqueous solution of sodium thioglycollate markedly reduces water diuresis in rats and cannot be used by either route to demonstrate unequivocally whether posterior pituitary antidiuretic principle has been inactivated. By the intravenous route in rats, thioglycollate does not interfere with diuresis and can be shown, as in the dog, to abolish the antidiuretic action of Pitressin. Therefore, there is no controlled experimental evidence that Pitressin contains more than one antidiuretic principle.

Oxytocic Activity of Purified Vasopressin

Summary Evidence has been obtained with a highly purified preparation that vasopressin, in addition to its pressor and antidiuretic activities, possesses intrinsic oxytocic action as one of its pharmacological properties, in contrast with purified oxytocin which appears not to possess pressor or antidiuretic activity. For each 100 units of vasopressor-antidiuretic activity there is intrinsic “oxytocic” activity represented by approximately 5 units as determined by the isolated rat uterus assay or by approximately 13-15 units by the chicken blood pressure depressor assay. The evidence that vasopressin possesses milk-ejection activity about one-fifth that of oxytocin has been discussed.

Effect of 2,3-dimercaptopropanol (BAL) on acute poisoning by tervalent and quinquevalent antimonial drugs.

Summary In rats, the acute lethal action of tartar emetic is significantly reduced by the administration of BAL. BAL increases the mortality rate in rats receiving Fuadin, Neostam or Neostibosan. The mortality rate in rats given large doses of Stibanose is not reduced by BAL.

Effect of Vitamin-E Deficiency on Amount of Gonadotropin in the Anterior Pituitary of Rats.

Summary The gonadotrophin content of the anterior pituitary taken from vitamin-E deficient rats, 315 to 469 days of age, was determined. The weights of testes, seminal vesicles and anterior prostates of groups of male rats hypophysectoniized at 21 dtays of age and subsequently injected with suspensions of frozen-dried anterior pituitaries were compared. The testes of the hypophysecto-mized rats which received the pituitary suspension from vitamin-E deficient male or female rats were significantly heavier than those of rats which received pituitary powder from the controls. There was no difference in the weights of the seminal vesicles or anterior prostates. It is concluded that the gonadotrophin content of the anterior pituitary gland is elevated in older vitamin-E deficient male and female rats. The relationship of these findings to the changes in the gonads in vitamin-E deficiency are discussed.

Chemotherapy of Experimental Leishmaniasis.

Summary A method for the routine evaluation of drugs for the therapy of visceral leishmaniasis in the hamster is described. No drug superior to Stibanose, Neostam or Neostibosan was discovered in tests of 27 other antimonials or of 158 additional metallic and non-metallic organic compounds.