The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.
Gel filtration and radioimmunoassay were used to determine the molecular size and immunochemical reactivity of parathyroid hormone present in gland extracts, in the general peripheral circulation, and in parathyroid effluent blood (obtained by venous catheterization) from patients with hyperparathyroidism, as well as from calves and from cattle. Hormone secreted in vivo from normal bovine parathyroid glands and from human parathyroid adenomas is similar in size to the 84-amino-acid peptide (molecular weight of 9500) extracted from the parathyroids. However, much of the immunoreactive parathyroid hormone present in the peripheral circulation of man and cattle is smaller than the extracted or secreted hormone; it elutes from gel columns at a position corresponding to a molecular weight of about 7000. The immunological characteristics of extracted and secreted hormone are identical, while hormone in the general circulation is immunologically dissimilar to extracted and secreted hormone. The results indicate that parathyroid hormone secreted from the parathyroids in man and cattle is at least as large as the molecule extracted from normal bovine glands. However, once secreted into the circulation the hormone is cleaved, and one or more fragments, immunologically dissimilar to the originally secreted hormone, constitute the dominant form of circulating immunoreactive hormone.Despite recent advances in the structural characterization of parathyroid hormone (extracted from parathyroids) (1)(2)(3) and the synthesis of a biologically active peptide consisting of the first 34 amino acids (5), recent findings based on radioimmunoassays have suggested that the biosynthesis and secretion, as well as the metabolism, of endogenous parathyroid hormone in man and animals is quite complex and that, in fact, the exact chemical nature of the active circulating form of the hormone is not yet known (3,(6)(7)(8)(9).Berson and Yalow reported that plasma parathyroid hormone is immunologically different from hormone extracted from tissue, but the chemical basis of this heterogeneity of plasma hormone could not then be determined (7). Other workers have subsequently reported finding immunological differences between the parathyroid hormone extracted from the glands and that found either in plasma or secreted into culture medium during incubation of parathyroid tissue (8, 9). In fact, Arnaud, et al. (6)
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