Frederick R. Singer

An evaluation of antibodies and clinical resistance to salmon calcitonin

21 patients with Pagets disease of bone and one with osteoporosis were studied to detect development of antibodies to salmon calcitonin during chronic therapy. Antibody titers ranged from 1:40 to 1:30,000 in plasma obtained after treatment of 11 patients. Radio-immunoelectrophoresis revealed that the antibodies were restricted to the gammaG class. One patient, W. O., with Pagets disease initially responded to treatment with a decrease in bone turnover, but later became resistant to the hormone in association with the appearance of a very high titer (1:30,000) of antibody against salmon calcitonin. A 1:10 dilution of his plasma was shown to completely inactivate 20 mMRC units/ml of salmon calcitonin as detected by bioassay in rats; slight inactivation was detected at a 1:200 dilution. All other patients continued to respond to salmon calcitonin despite the development of antibody to the hormone in ten cases. No evidence of systemic allergic reactions or other toxicity was found in any patient. The data suggest that although antibody formation may occur in as many as 50% of patients treated with salmon calcitonin, this antibody response is unlikely to be of clinical significance in most patients. However, in an occasional patient, a marked antibody response may occur which interferes with the therapeutic use of the hormone.

Multiple immunoreactive forms of calcitonin in human plasma

Abstract The nature of calcitonin in the plasma of nine patients with medullary carcinoma of the thyroid was evaluated by gel filtration on a column of Bio-Gel P-10 and radioimmunoassay of the fractions obtained. Four distinct peaks of immunoreactive calcitonin were found in each plasma; three were of higher molecular weight than monomer human calcitonin.

Immunoassay for human calcitonin. II. Clinical studies

Abstract A sensitive and specific radioimmunoassay for human calcitonin has ben developed and applied to clinical studies. Under optimal conditions, the assay can be used to detect 50–100 pg of calcitonin per milliliter of human plasma. Patients with medullary thyroid carcinoma had concentrations of plasma calcitonin that could be readily detected by the assay and ranged from 60 to over 100,000 pg per milliliter. In these patients, hypercalcemia induced by calcium infusion resulted in up to a 20-fold increase in calcitonin concentration. Hypocalcemia induced by EDTA infusion suppressed the secretion of calcitonin in each patient tested. Glucagon infusion had a variable effect on calcitonin secretion. Calcitonin could not be detected with confidence in any basal peripheral sample of plasma taken from normal adults or hypercalcemic patients. Calcitonin could not be unequivocally detected in the majority of thyroid venous plasma samples taken from patients with hypercalcemia. These results suggest that the concentration of calcitonin in the peripheral blood of adults is much lower than previously reported. Further studies are required to determine if calcitonin circulates in peripheral blood even after hypercalcemic stimulation in normal human subjects.

Acute effects of calcitonin on bone formation in man

Abstract Intravenous administration of porcine calcitonin or salmon calcitonin to a normal subject or to patients with Pagets disease of bone produces a marked decrease in the urinary excretion of hydroxyproline-containing peptides. The excretion of both polypeptides (retentate after dialysis) and oligopeptides (diffusate after dialysis) decreases after calcitonin. Since it has been shown previously in patients with Pagets disease that the retentate hydroxyproline reflects predominantly (bone) collagen synthesis, it is likely that bone collagen synthesis decreases acutely, accompanying the decrease in degradation of bone produced by calcitonin.

Peripheral metabolism of bovine parathyroid hormone in the dog

Four dogs were infused with highly purified bovine parathyroid hormone until constant levels of immunoreactive hormone were attained in the circulation. Simultaneous samples of plasma were then obtained from the aorta, from hepatic, renal, and femoral veins, and later from a pulmonary artery and the left ventricle. Radioimmunoassay of these samples revealed mean arteriovenous differences of -23% across the liver and -19% across the kidney. No significant differences were found across the lung or lower extremity. After termination of the infusion the disappearance rate of immunoreactive hormone in external jugular-venous blood was multiexponential: the predominant initial T 1/2 was 4, 6, and 8 min, and the terminal component was 60, 54, and 99 min. respectively, in 3 dogs.

Mithramycin Treatment of Intractable Hypercalcemia Due to Parathyroid Carcinoma

MITHRAMYCIN, a cytotoxic antibiotic used mainly in the therapy of embryonal tumors of the testis,1 2 3 4 5 has been stated to lower serum calcium levels even in normocalcemic patients.2 , 6 , 7 Its...

PARATHYROID FUNCTION IN PATIENTS WITH PAGET'S DISEASE TREATED WITH SALMON CALCITONIN

To study the possibility of secondary hyperparathyroidism in patients with Pagets disease treated with calcitonin over a long period, we investigated parathyroid function in eleven patients treated with salmon calcitonin (CT) for up to 23 months and in one patient treated with human CT. Basal plasma calcium, immuno‐reactive parathyroid hormone (PTH) and serum phosphorus levels were all in the normal range before and after the treatment and did not change significantly during the treatment. In all patients, an acute fall in calcium and a rise in PTH occurred after the initial injection of CT. The rise in PTH was proportional to the fall in calcium and similar to that observed in normal subjects. After treatment, the rise in plasma PTH remained the same in relation to the fall in calcium, indicating that the responsiveness of the parathyroid glands to the hypocalcaemic challenge was unaltered, and that secondary hyperparathyroidism was not present in these patients.

Dextran-charcoal and dioxane phase separation methods in the radioimmunoassays for parathyroid hormone and calcitonin.

Dioxane precipitation and dextran-charcoal adsorption were used to separate free from bound /sup 125/I-labelled hormone in the radioimmunoassays of calcitonin and parathyroid hormone. Changes in the fraction of bound radioactivity, independent of hormone concentrations, were seen with changes in temperature, plasma concentration, time of standing, and amount of dioxane or dextran-charcoal added. Characterization of these variables affecting bound radioactivity, and careful standardization of the conditions of phase separation, indicate that dioxane precipitation is a satisfactory method for the calcitonln immunoassay while dextran-charcoal adsorption provides the most reliable results in the parathyroid hormone immunoassay. (INIS)

Chemistry and Physiology of the Calcitonins: Some Recent Advances

This chapter discusses the chemical and physiological properties of calcitonins. Porcine calcitonin disappears with an initial half-time of 2–5 min, compared with 21 min for salmon calcitonin. Comparable studies including human calcitonin as well as porcine and salmon show that the disappearance rate of human hormone was intermediate between the other two. In all cases, the in vivo half-times are very much faster than those observed during in vitro plasma incubation. Hence, breakdown in peripheral plasma cannot alone be responsible for degradation of calcitonins in vivo. These studies all suggest, however, that at least a part of the explanation for the increased potency of salmon calcitonin may be increased resistance to destruction, leading to longer maintenance of effective blood levels of calcitonin.

Radioimmunoassays for Calcitonins: Clinical and Experimental Studies

This chapter discusses the application of immunoassays for bovine, salmon, and human calcitonin to the clinical and experimental studies of the secretion of the peptide in each of these species. The complete amino acid sequence has been determined for five species of calcitonin, namely porcine, bovine, ovine, human, and salmon calcitonin. Because of the marked structural differences among human, salmon, and the other calcitonins, it has been necessary to develop separate and specific immunoassays for the peptides to study control of secretion in a wide variety of species. The purified preparations of each of the calcitonins are radioiodinated for use as tracer. Calcitonin could be readily detected in the peripheral blood of the bovine species. As with other animals, calcium infusion produced a four- to sevenfold increase in plasma calcitonin, demonstrating the directly proportional control by calcium of calcitonin secretion in this species. There is no significant difference between plasma calcium concentration in bulls and cows. The reasons for this higher concentration of calcitonin in bulls may be related to the high dietary intake of the bovine species.