Paul L. Munson

Thyrocalcitonin: hypocalcemic hypophosphatemic principle of the thyroid gland.

A factor that lowers serum calcium and inorganic phosphate in rats has been purified 500-fold from 0.1N HCl extracts of hog thyroid glands. It is distinct from thyroxine and triiodothyronine and appears to be a polypeptide.

Thyrocalcitonin inhibition of bone resorption induced by parathyroid hormone in tissue culture.

Added thyrocalcitonin greatly diminished parathyroid-hormone-induced resorption of bone in tissue culture. The results indicate that bone is primary site of action of thyrocalcitonin.

STUDIES ON THE ROLE OF THE PARATHYROIDS IN CALCIUM AND PHOSPHORUS METABOLISM

The parathyroids constilute the major factor responsible for the constancy of the blood calcium concentration necessary for normal development and maintenance of the skeletal tissues. In recent years, this important hormonal activity has not been accorded the intensive and widespread research endeavor which it deserves, and it is encouraging to note that there are now indications of a new burst of investigational effort in this area. Here is an endocrine system in which the hormonal activity is still known only in the crude state; its chemical nature is still largely a matter for conjecture; the scope and mechanism of its actions are still incompletely defined; and its potential therapeutic applications await necessary prior advances in basic knowledge. It is an attractive field for further scientific exploration. At the risk of slighting an important opportunity for a definitive review of the present status of knowledge about the parathyroids, we have chosen to present for your critical appraisal a summary of the largely unpublished work carried out in our laboratory during the past three years. In the interest of relative brevity, only scant mention will be made of pertinent observations made by other investigators. The over-all direction of our investigation is toward the elucidation of the nature and mechanism of action of the hormonal activity of the parathyroids. Our major instrument in these studies has been the parathyroidectomized rat. Surgical excision of the parathyroids from the strain of albino rats we use (obtained commercially from the Holtzman Rat Company) is not difficult, and can be carried out speedily without obvious damage to the thyroid. There is, however, a certain amount of hemorrhage associated with the operation and, in a considerable proportion of cases, this bleeding may be extensive enough to result in death from loss of blood. In all cases, it was feared that the amount of blood lost might affect the concentrations of calcium and inorganic phosphate ions significantly. Accordingly, Doctor Greep, my collaborator in most of these studies, revived the procedure, originally introduced by Erdheim, of destroying the parathyroid tissue with an electrocautery. This procedure is a convenient one. I t is performed under ether anesthesia with the aid of a dissecting microscope and requires only about two minutes time per rat. There is no hemorrhage and no mortality other than that directly attributable to the loss of the parathyroids. In our experiments, we have not been troubled by interference from functional accessory parathyroid tissue missed by the surgeon. In a series of early experiments,8 in collaboration with Oscar Iseri and Doctor Greep, male albino rats, 40 to 50 days old, were placed on a purified diet (modified from Shaw 4, which is essentially free of calcium but otherwise nutritionally

Production of an antibody to bovine parathyroid hormone

Abstract The preliminary experiments reported in this communication provide the first published evidence of the production of a specific antibody to parathyroid calcium mobilizing hormone, indicated by Rasmussen and Craig (1961, 1962) to be a polypeptide with a molecular weight of the order of 9000.

THE INFLUENCE OF THE PARATHYROIDS ON THE CALCIUM CONCENTRATION OF MILK

The importance of the parathyroids in the regulation of over-all calcium metabolism led us to investigate the possibility that parathyroid hormone may influence the calcium-concentrating function of lactating mammary glands. Experiments on lactating rats did reveal changes in the composition of the milk 24 hours after removal of the parathyroid glands. The concentration of calcium in the milk was increased markedly in spite of a greatly depressed serum calcium level. The milk appeared obviously thicker, and there was indeed an increase in the total solids. The increase in calcium content, however, was not entirely accounted for by the reduction in per cent water, as the calcium concentration, expressed as milligrams per gram of milk solids, was significantly higher after parathyroidectomy than in control shamoperated rats. Administration of parathyroid extract, immediately after parathyroidectomy, prevented the decrease in water content of the milk as well as the fall in serum calcium. The increase in calcium concentration of the milk was not so clearly prevented.

Chemical nature and properties of parathyroid hormones.

Abstract 1.1. A second hormone of the parathyroid glands, calcitonin, that lowers blood calcium has been postulated by Copp and Cameron on the basis of experiments in intact dogs. The reported hypocalcemic effects are characterized by rapid onset, small magnitude, and short duration. 2.2. The classic parathyroid hormone, a calcium-mobilizing polypeptide, has been most effectively purified from a phenol extract of bovine parathyroid glands by the use of countercurrent distribution or gel filtration. The molecular weight has been estimated at approximately 9000, with 76 to 83 amino acid residues in a single chain. Purified polypeptide preparations of lower molecular weight and lower specific biological activity have been obtained from extracts made with dilute hydrochloric acid and with acetic acid. 3.3. One plausible but unproved explanation of the loss, recovery, or enhancement of biological activity of the hormone when treated with various reagents is the reversible oxidation and reduction of the methionine residue (with a subsequent conformational change in the molecule about its active site(s)). 4.4. Biological assay methods in current use for following the purification of parathyroid hormone and for standardization are not sensitive enough for satisfactory quantitation of the hormone in blood or urine. However, new in vitro and immunochemical methods may satisfy this need and in addition provide the means for investigating possible species differences.

The error of replicated potency estimates in a biological assay method of the parallel line type.

In the practice of biological assay the most widely used formulas [2, 3] for the variance and the fiducial limits of a potency estimate take account of intra-assay error only. The assumption implicit in the use of these formulas that inter-assay variation need not be considered may be tested by comparing the variation predicted by the formula with the variation actually observed in replicated assays of unknowns. Such a test in a collaborative penicillin assay of the parallel line type analyzed by Bliss [4] showed that the actual error of the log potency estimate (M) was considerably and significantly greater than the error predicted from intra-assay statistics. It was suggested that a large portion of the discrepancy might be due to errors in dosage of test substances. A similar suggestion was made by Dews and Berkson [5] in their consideration of the actual error of quantal assays. Excess variability in M occurring during collaborative trials for International Standards of several antibiotics [6-10] was at times associated with, although not fully explained by, significant deviations from linearity or from parallelism. Although many of the observed discrepancies were small in an absolute senlse, they were detected because of the considerable innate (within-group) precision of the assay methods. The actual error of M for several other International Standards [11-13] was also greater than predicted by the usual computations. Interactions of M with replicate samples of the same milk within assays and also between assays were observed by Clarke [14] in parallel line assays for riboflavin potency.

A simple method for the determination of urinary dehydroepiandrosterone

Abstract A convenient new method for the quantitative measurement of human urinary dehydro ep iandrosterone (DHA) is described. Its specificity, reliability and reproducibility are discussed. Due to its simplicity, the method may be used in clinical laboratories for routine as well as research purposes.

The phosphaturic response of thyroparathyroidectomized dogs to the administration of parathyroid hormone by unilateral renal arterial infusion

SummaryAcutely thyroparathyroidectomized dogs were administered partially purified parathyroid hormone by way of the left renal artery. When the hormone was given by this route at a relatively high dose, either by injection of 30 or more units or as a continuous infusion at the rate of 30 units/hour, the renal response, an increase in the % of filtered phosphate excreted, was rapid and essentially identical by both kidneys. On the other hand, when the parathyroid hormone preparation was infused into the renal artery at a relatively slow rate (1–12.5 units/hour), the response either was confined to the infused kidney or it was greater by the infused kidney than by the noninfused kidney. Control infusions of physiological salt solution or of a nonparathyroid tissue extract resulted in no differential effect on the infused kidney. These results, added to those of similar experiments in intact dogs by Pullman, Lavender, Aho, and Rasmussen, support the conclusion that parathyroid hormone acts directly on the mammalian renal tubule.

Concentration of parathyroid hormone activity by chromatography on carboxymethylcellulose

Abstract A method for the further purification of a fraction salted-out from a dilute hot hydrochloric acid extract of untreated ground bovine parathyroid glands is described. Chromatography on carboxymethylcellulose using a NaCl gradient rising to I M at pH 4.68 results in an active Ca-mobilizing fraction with a 6-fold increase in specific activity in moderate yield. This can be further increased 2- to 6-fold by recycling and eluting with a gradient rising to 0.5 M salt. The method is applicable to starting material containing either high or low amounts of activity.