Toad

About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.

The isolation from human blood plasma of a substance having positive inotropic action on the isolated toad heart

Abstract: The positive inotropic action of blood plasma on isolated hearts has been known for a long time (Bowditch, 1871; Ringer, 1885; Clark, 1913; Hajdu, 1957; Hajdu, Leonard & Akers, 1957a; Hajdu, Weiss & Titus, 1957 b), and the observations recorded by various authors suggest that a number of different plasma components are responsible for positive inotropic activity. Hajdu et al. (1957b) isolated a substance with digitalis-like activity from mammalian blood and identified it as a-palmitoyllysolecithin. Hajdu et al. (1957a) found that certain plasma protein fractions isolated from hypertensive patients showed a greater inotropic activity on the isolated amphibian heart than those isolated from normotensives. Tanz (1960a, b), Tanz & Kerby (1961) and Sayers & Solomon (1960) have found that aldosterone was responsible in part for the positive inotropic activity of human plasma. Nayler & McCulloch (1960b) found a heat-stable diffusible factor present in human and animal plasma which possessed positive inotropic activity. In preliminary investigations of the pharmacological properties of this heat-stable diffusible plasma factor we have shown that it improves the efficiency of the isolated toad heart and that it exerts a marked effect on the rate at which tension is produced by isolated toad ventricular muscle. Seasonal variation in the activity of toad plasma was observed, suggesting a hormonal control over the activity of this plasma factor in the toad. The present paper describes the isolation of a substance with inotropic activity from heparintreated human plasma.

The production of two molecular classes of antibody in the toad, Xenopus laevis, homologous with mammalian gamma-M (19S) and gamma-G (7S) immunoglobulins.

Abstract: A good immune response to BGG was induced in the toad, Xenopus laevis, with the production of precipitating antibody. A large amount of macroglobulin is present in normal toad serum, and forms a major peak on Sephadex G-200 gel filtration. Two classes of immunoglobulins, homologous with mammalian γM (19S) and γG (7S) antibody, are produced during the course of immunization. The conversion from 19S to 7S antibody activity occurred about a month after primary immunization.

Ultrastructure of the renal juxtaglomerular complex and peripolar cells in the axolotl (Ambystoma mexicanum) and toad (Bufo marinus).

Abstract: Renal juxtaglomerular regions were examined in the axolotl (Ambystoma mexicanum and toad (Bufo marinus). Prominent granulated peripolar epithelial cells were found surrounding the origin of the glomerular tuft in the axolotl. These cells resembled the peripolar cells recently discovered in mammalian species. They contained multiple electron-dense cytoplasmic granules, some of which showed a paracrystalline substructure and signs of exocytoxic activity. Such cells were difficult to find and smaller in the toad. In contrast, granulated juxtaglomerular arteriolar myoephithelial cells were much more readily found and larger in the toad than in the axolotl. No consistent differences were noted in juxtaglomerular cells or their granules in response to changes in environmental chloride concentration.