Osteopetrosis.
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Bone Marrow Transplantation↗
Biomedical subjects
F R Singer
Publications and source records attributed to F R Singer.
Clinical efficacy of salmon calcitonin in Paget's disease of bone.
Clinical interest in salmon calcitonin began in 1972 when this peptide was shown to be effective in the treatment of Paget's disease. Salmon calcitonin is more potent than porcine calcitonin, with human calcitonin intermediate in potency. Salmon calcitonin is a highly effective therapeutic agent in the treatment of Paget's disease. During chronic treatment with salmon calcitonin, alkaline phosphatase activity and urinary hydroxyproline excretion decrease on an average of 50% in patients with Paget's disease. Patients may experience a variety of clinical benefits during chronic treatment, including relief of bone pain, a reversal of neurological deficits, stabilization or improvement of hearing loss, and improvement of vascularity of bone. Radiologic healing of osteolytic lesions in particularly striking with calcitonin treatment. Paget's disease patients prefer treatment with salmon calcitonin administered by means of a nasal spray. Salmon calcitonin has an excellent safety profile and produces mild side effects in a small percentage of patients. The most common side effects associated with salmon calcitonin administration are nausea and facial flushing. It is unusual to observe severe side effects. In about 20% of patients, production of antibodies may neutralize the effects of the exogenously administered calcitonin; these patients respond to human calcitonin. At this time salmon calcitonin should still be considered a valuable therapeutic agent in the treatment of Paget's disease, particularly in patients with osteolytic lesions.
Calcitonin↗
Abundant expression of parathyroid hormone-related protein in primary rat aortic smooth muscle cells accompanies serum-induced proliferation.
Parathyroid hormone-related protein (PTHrP), which is responsible for producing hypercalcemia in patients with humoral hypercalcemia of malignancy, has recently been identified in several normal tissues. Because PTHrP, like parathyroid hormone (PTH), is known to exhibit vasodilatory properties, we investigated the expression and regulation of PTHrP mRNA in cultured rat aortic smooth muscle cells (SMC). We report here that PTHrP mRNA is expressed in SMC and is markedly induced by serum in a time- and concentration-dependent fashion. Addition of 10% fetal calf serum to serum-deprived, confluent cells, resulted in a marked induction of PTHrP mRNA by 2 h with a peak at 4-6 h. PTHrP was detected in SMC by immunocytochemistry and radioimmunoassay of conditioned medium, and was shown to be up-regulated within 24 h after the addition of serum. The serum induction of PTHrP mRNA was blocked by actinomycin D and by cycloheximide indicating the need for protein synthesis to evoke the serum effect on PTHrP gene transcription. In addition, treatment with dexamethasone, which has been previously shown to reduce the constitutive expression of PTHrP in human cancer cells, also blunted the serum induction of PTHrP mRNA in SMC. Treatment of quiescent cells with the serum mitogens platelet-derived growth factor or insulin-like growth factor-I had no effect on PTHrP, whereas the vasoactive peptides endothelin, norepinephrine and thrombin stimulated PTHrP expression. Exogenous addition of recombinant PTHrP-(1-141) had no significant effect on SMC DNA synthesis as measured by [3H]thymidine incorporation. In summary, the abundance of PTHrP mRNA and the characteristics of its regulation in SMC suggest a major role for PTHrP as a local modulator in vascular smooth muscle.
Animals↗
Effectiveness of a 24-hour infusion of etidronate disodium in the treatment of hypercalcemia of malignant disease. A dose-ranging pilot study.
A dose-ranging, baseline-controlled study was undertaken to assess the safety and effectiveness of a 24-hour infusion of etidronate disodium in treating patients with hypercalcemia of malignant disease. Patients with hypercalcemia refractory to at least 48 h of saline loading (greater than 3 1/day) with two albumin-adjusted serum calcium values between 11.1 and 12.0 mg/dl or one albumin-adjusted serum calcium greater than 12.0 mg/dl within 48 h of therapy were admitted to the study. A total of 26 patients were treated in a dose-escalating fashion with 5, 10, 15, 20 or 25 mg/kg of intravenous etidronate disodium over 24 h. Patients treated with 5, 10 or 15 mg/kg did not have significant reductions in albumin-adjusted serum calcium during the first 7 days. In the 6 patients who made up the 20 mg/kg group, adjusted serum calcium levels fell from an average of 13.8 +/- 0.5 mg/dl on day 1 before infusion to 11.7 +/- 0.3 mg/dl (p less than 0.05) by day 7. In the 8 patients in the 25 mg/kg group, adjusted serum calcium levels decreased from an average of 12.9 +/- 0.5 mg/dl on day 1 before infusion to 10.9 +/- 0.4 mg/dl (p less than 0.05) by day 7. All 8 patients in the 25 mg/kg group achieved a fall in albumin-adjusted serum calcium to less than 11.1 mg/dl within the 1 week with a minimum decrement of 0.6 mg/dl and a maximum of 5.5 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)
Etidronic Acid↗
Treatment of hypercalcemia of malignancy with intravenous etidronate. A controlled, multicenter study. The Hypercalcemia Study Group.
In a prospective, randomized, double-blind, multicenter study, 202 patients with cancer from 19 medical centers were treated for hypercalcemia of malignancy with daily intravenous infusions of etidronate disodium (136 patients) or saline alone (66 patients) for 3 consecutive days. Patients also received up to 3.25 L of saline daily during the treatment period. Of 157 patients for whom data could be evaluated for efficacy, 63% (72/114) of etidronate-treated and 33% (14/43) of saline-treated patients had a normalization of total serum calcium levels. When serum calcium levels were adjusted for albumin (147 assessable patients), 24% of the etidronate- and 7% of the saline-treated patients responded to treatment. No serious side effects or treatment-related deaths occurred. When accompanied by adequate hydration and diuresis, intravenous etidronate was safe and more effective than hydration and diuresis alone in controlling hypercalcemia of malignancy.
Double-Blind Method↗
Pathogenesis of hypercalcemia of malignancy.
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Animals↗
Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: performance in the differential diagnosis of hypercalcemia and hypoparathyroidism.
Parathyrin (parathyroid hormone; PTH) was measured with three immunoassays: a two-site immunochemiluminometric (ICMA) and a two-site immunoradiometric (IRMA) method for intact PTH, and a sensitive radioimmunoassay for mid-region or "total" PTH, measuring both intact hormone and inactive fragments. Single specimens from normal subjects and from individuals with primary hyperparathyroidism, hypercalcemia associated with malignancy, and hypoparathyroidism were analyzed with all three methods. All individuals with primary hyperparathyroidism showed absolutely above-normal concentrations with the mid-region RIA, 28 of 29 did with the ICMA, and 21 of 29 did with the IRMA. PTH concentrations in primary hyperparathyroidism were most increased relative to normal subjects with the mid-region assay (10.4 times), less so with the intact assays (ICMA 5.5 times; IRMA 5.3 times). Concentrations of intact PTH were suppressed below normal in nearly all patients with hypercalcemia associated with malignancy, as measured with the ICMA (26 of 30) and the IRMA (28 of 30) assays. In marked contrast, results for mid-region PTH were normal or slightly above normal, consistent with studies suggesting that the parathyroids secrete both intact hormone and inactive fragments, the former being more sensitive to suppression by hypercalcemia. In hypoparathyroidism PTH concentrations were detectable but below normal in all patients by the intact assays and in all but one patient by the mid-region assay. These low concentrations are probably due to a nonspecific serum effect that could be resolved with selection of a more appropriate standard matrix. Although all three assays are useful in the differential diagnosis of hypercalcemia, two-site intact assays are more convenient and more specific in patients with compromised renal function.
Diagnosis, Differential↗
Purification and N-terminal amino acid sequence of the tartrate-resistant acid phosphatase from human osteoclastoma: evidence for a single structure.
Tartrate-resistant acid phosphatase type-5 was purified to apparent homogeneity from human osteoclastomas by sequential chromatography on CM-Sepharose, Phenyl-Sepharose, concanavalin A-Sepharose, FPLC Superose-12, and FPLC Mono-S. The purification over the original tissue extract was 1167-fold, with a yield of 16%. An identity in the N-terminal amino acid sequence and Mr was found between this enzyme and two type-5 tartrate-resistant acid phosphatases isolated from hairy cell leukemia spleen. However, they appeared to be different as assessed by amino acid composition. In contrast to a previous report, no evidence was found for two subunits of the tartrate-resistant acid phosphatase.
Acid Phosphatase↗
Parathyroid hormone-related protein.
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Animals↗
Multiple osteocalcin fragments in human urine and serum as detected by a midmolecule osteocalcin radioimmunoassay.
Reliable markers of bone formation are essential to the investigation of metabolic bone disorders. In this regard, evidence indicates that circulating levels of human osteocalcin (OC) correlate with the skeletal isoenzyme of alkaline phosphatase and can be used as an index of bone formation. A disadvantage of using serum OC as a marker of formation is its diurnal variation. To address this problem we carried out our studies to determine the usefulness of urine in the assessment of bone turnover. Using a midmolecule specific human OC RIA, we were able to detect OC in urine of normal adults (42 mugeq/g creatinine), normal children (849 mu/geq/g creatinine), and Paget's disease patients (613 mugeq/g creatinine). Immunoreactive fragments of OC in human urine and human serum were separated by high pressure liquid chromatography. Multiple fragments were found in normal adult urine that were not detected in normal adult serum. Uremic and Paget's disease sera contain several immunoreactive forms of OC, other than the intact molecule, not found in normal adult serum. Additionally, both Paget's disease sera and urine contained a specific peak of immunoreactive material, eluting at 25% acetonitrile, that was not found in any other serum or urine tested. Urinary OC (uOC) correlated with both skeletal alkaline phosphatase (r = 0.91) and serum OC (r = 0.83), indices of skeletal formation. While uOC has a diurnal variation similar to that of serum OC, determinations of 24-h uOC give integrated values of daily bone turnover rates. Z-Score analysis indicates that uOC (z = 14.04) is better able to distinguish between normal children with high bone turnover and normal adults than either skeletal alkaline phosphatase (z = 8.87) or serum OC (z = 9.01).
Adult↗
Development of an immunoassay for human serum osteoclastic tartrate-resistant acid phosphatase.
A tartrate-resistant acid phosphatase (TrACP), which has been suggested to be very similar to the osteoclastic TrACP, was partially purified from the spleen of a patient with hairy cell leukemia. The purification procedure consisted of carboxymethyl-Sepharose, phosphocellulose, Sephacryl S-200, and phenyl-Sepharose chromatographies. Polyclonal antibodies were generated in guinea pigs with a titer of at least 1:6000. Immunohistochemical staining of fetal rat tibia with the antisera revealed that only the lysosomes of osteoclasts, but not osteoblasts, were stained. An enzyme-linked immunosorbent assay (ELISA) was developed with the antisera. There was no cross-reactivity with 1) partially purified acid phosphatases (ACPs) from normal human and beef spleens, 2) ACPs in extracts of human osteoblastic cells, 3) purified bovine bone matrix TrACP, or 4) commercial prostatic ACP. However, extracts of giant cell bone tumors, containing large amounts of bona fide osteoclasts, showed large amounts of cross-reactive material, which diluted in parallel with the partially purified hairy cell leukemic TrACP in the ELISA. Commercial serum band 5b TrACP also displaced in parallel with the partially purified hairy cell leukemic TrACP. Immunoblotting studies revealed that the antiserum, but not nonimmune guinea pig serum, reacted with the homogeneous hairy cell leukemia splenic band 5 TrACPs, which were recently purified by our laboratory. Preliminary application of the ELISA to sera of patients with metabolic bone diseases revealed that normal healthy individuals had measurable amounts of the immunoreactive material, and patients with Paget's disease or hyperparathyroidism, who should have high bone turnover, had elevated levels of this immunoreactive material in their sera. In contrast, the level of serum osteoclastic TrACP in a patient with an acute lymphatic leukemia was normal. In summary, 1) we have shown that hairy cell leukemia splenic TrACP shares significant immunological similarity with the osteoclastic TrACP and with the serum band 5b TrACP, and 2) the ELISA holds promise for a sensitive and specific assay for bone resorption.
Acid Phosphatase↗
Role of the bisphosphonate etidronate in the therapy of cancer-related hypercalcemia.
Bisphosphonates (formerly diphosphonates), analogues of endogenous pyrophosphates, are potent inhibitors of osteoclastic bone resorption. While the exact mechanism of action remains poorly understood, etidronate, the only bisphosphonate currently available in the United States for the treatment of hypercalcemia, decreases the elevated serum calcium levels and alleviates the symptoms associated with hypercalcemia of malignancy. Both open and controlled clinical studies have demonstrated that this agent, administered at a dose of 7.5 mg/kg/d in 2-hour intravenous infusions over 3 to 7 days, promotes normocalcemia. In a randomized study, etidronate was shown to be superior to maximally approved doses of calcitonin. Moreover, when administered to patients without overt renal failure (serum creatinine less than 2.5 mg/dL), the drug is remarkably free of significant acute toxicity and side effects. Therefore, an important therapeutic aspect of this agent is that it permits concurrent antibiotic and chemotherapy administration. Judicious use of appropriate and specific pharmacologic intervention strategies in the patient with cancer-related hypercalcemia is expected to enhance quality of life, improve systemic cancer therapy tolerance, and reduce the morbidity of this serious neoplastic complication.
Animals↗
Measurement of parathyroid hormone.
Interpretation of serum immunoreactive PTH measurements requires an understanding of the secretion, metabolism, and heterogeneity of circulating immunoreactive PTH. Both intact hormone and biologically inactive carboxyl fragments containing the middle and C-terminal regions are secreted by the parathyroid glands. Inactive fragments also are produced peripherally by metabolism of intact hormone by liver and kidney. Inactive fragments represent 75 to 95% of the total immunoreactivity in serum, a consequence of their long half-life in vivo as compared with intact hormone. Immunoassays for PTH can be divided into those measuring intact hormone (N-terminal, intact) and those measuring both inactive fragments and intact hormone (mid-region, C-terminal, polyvalent). The latter principally measures inactive fragments because of their greater concentration as compared with intact hormone in peripheral serum. The clinical utility of PTH assays varies considerably because of differences in their specificity and sensitivity. Serum PTH levels have been more often observed to be elevated in individuals with primary hyperparathyroidism with the use of research quality radioimmunoassays that recognize both inactive fragments and intact hormone than with conventional N-terminal or intact assays. Homologous mid-region assays have provided exceptional clinical sensitivity in confirming primary hyperparathyroidism. Comparison of a sensitive mid-region radioimmunoassay with a recently developed two-site, noncompetitive chemiluminescent immunoassay for intact PTH indicated that both methods were highly useful in the differential diagnosis of hypercalcemia. The mid-region assay provided the best diagnostic sensitivity in primary hyperparathyroidism with more elevated levels of PTH. The sensitivity of the intact assay was good, a significant improvement over conventional N-terminal and intact assays. The specificity of the intact assay was clearly superior, with measured PTH levels found to be suppressed to below normal in most subjects with hypercalcemia associated with malignancy. In contrast, measured levels were primarily normal with the mid-region assay. The higher levels of immunoreactive PTH observed in nonparathyroid hypercalcemia with the mid-region assay are in agreement with the measurement of biologically inactive carboxyl fragments, which continue to be secreted in hypercalcemia.
Amino Acid Sequence↗
Vitamin D metabolite-mediated hypercalcemia and hypercalciuria patients with AIDS- and non-AIDS-associated lymphoma.
Fifteen patients with lymphoma and hypercalcemia (greater than or equal to 11.0 mg/dL) were identified by screening the serum chemistry profile obtained from patients upon admission to the Los Angeles County/USC Medical Center. Seven of the 15 (47%) possessed a frankly elevated serum concentration of 1,25-dihydroxyvitamin D [1,25-(OH)2-D]. An additional patient with severe hypercalcemia (16.2 mg/dL) had a serum 1,25-(OH)2-D concentration in the midnormal range, not a suppressed value. To examine the potential existence of hypercalciuria in absence of overt hypercalcemia, prospective screening of 23 normocalcemic patients with lymphoma was undertaken. Four of the 23 patients (17%) had increased fractional urinary calcium excretion rates (0.35 +/- 0.3 mg calcium/100 mL glomerular filtrate [GF], mean +/- SE; normal, less than 0.16 mg/100 mL GF); two of the hypercalciuric patients had a frankly elevated serum 1,25-(OH)2-D concentration. Of the 19 hypercalcemic/hypercalciuric lymphoma patients identified, none had an elevated serum immunoreactive parathyroid hormone concentration. Fourteen of the 19 hypercalcemic/hypercalciuric patients (74%) suffered from B-cell neoplasms, three had Hodgkin's lymphoma, and two had adult T-cell leukemia/lymphoma. All hypercalcemic/hypercalciuric patients had widespread disease (stage III or IV). Six patients, four with hypercalcemia and two with hypercalciuria, had acquired immunodeficiency syndrome (AIDS). These data suggest that the deregulated synthesis of a 1,25-(OH)2-D-like metabolite is a common cause of hypercalcemia and hypercalciuria in patients with lymphoma including patients with AIDS-associated tumors.
Adult↗
Cobalamin and osteoblast-specific proteins.
Cobalamin deficiency has well-known hematologic and neurologic effects, but little is known about its other effects. We therefore studied the effect of cobalamin on osteoblast-related proteins. We found that mean (+/- 1 SD) levels of skeletal alkaline phosphatase in the blood were lower in 12 cobalamin-deficient patients (3.89 +/- 2.19 units per liter) than in 5 nondeficient and 5 iron-deficient control subjects (7.55 +/- 3.99 units per liter). The degree of the megaloblastic anemia correlated with the reduction in skeletal alkaline phosphatase levels (r = 0.67, P less than 0.01). With cobalamin therapy, levels of skeletal alkaline phosphatase rose in 11 of the 12 cobalamin-deficient subjects but not in the controls. The cobalamin-deficient patients also had significantly lower osteocalcin levels than the control subjects (1.11 +/- 0.77 vs. 1.84 +/- 0.49 nmol per liter). During cobalamin therapy, these levels rose in the cobalamin-deficient patients but not in the controls. In contrast to the levels of osteoblast-related proteins, hepatic alkaline phosphatase levels were similar in the patients and controls and were usually unaffected by cobalamin therapy. In vitro studies of calvarial cells from chicken embryos showed that their alkaline phosphatase content was cobalamin-dependent, thus supporting our in vivo observations in humans. Our findings suggest that osteoblast activity depends on cobalamin and that bone metabolism is affected by cobalamin deficiency, but we do not yet know whether cobalamin deficiency produces clinically important bone disease.
Adult↗
Osteoclasts in human osteopetrosis contain viral-nucleocapsid-like nuclear inclusions.
We report the discovery of nuclear inclusions in the osteoclasts of three unrelated patients with benign osteopetrosis that resemble the osteoclast inclusions characteristic of Paget's disease of bone. These inclusions are morphologically and dimensionally identical to the nucleocapsids of a virus of the Paramyxoviridae family. Supporting a possible viral association with benign osteopetrosis in the observation of the presence of antigens of respiratory syncytial virus, measles virus, and/or mumps virus in the cells of all five patients whose paraffin-embedded bone specimens were tested. These included two patients whose osteoclasts contained nuclear inclusions. No patients with the malignant form of the disease have been studied. There is as yet no proof that a virus is causally related to human osteopetrosis even though a virus can produce an avian form of the disease.
Adult↗
Hypercalcemia and abnormal 1,25-dihydroxyvitamin D concentrations in leprosy.
Two patients with lepromatous leprosy and hypercalcemia are presented. Serum immunoreactive parathyroid hormone and urinary cyclic adenosine monophosphate concentrations were suppressed. Serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations were elevated in one patient and normal in the other. Urinary hydroxyproline excretion was slightly high in both patients. Hypercalcemia resolved excretion was slightly high in both patients. Hypercalcemia resolved with prednisone therapy. Abnormal 1,25-(OH)2D production and/or metabolism may play a role in the pathogenesis of hypercalcemia in some patients with leprosy.
Adult↗
Gallium-67 citrate localization in osteoclast nuclei of Paget's disease of bone.
Gallium-67 citrate scintigraphy has been used to indicate the extent of bone involvement in patients with Paget's disease of bone and is an excellent marker in monitoring the effects of specific therapy. Since gallium uptake is dependent on cellular function, autoradiographic techniques can be applied to cells of Paget's lesions to understand better the mechanism of [67Ga]citrate uptake. Bone biopsies were obtained from sites of increased uptake using [67Ga]citrate scintigraphy in two patients with Paget's disease. In both patients electron microscopic autoradiographs demonstrated a high concentration of silver grains over the nuclei of osteoclasts. The cellular mechanism is unknown but may be related to the known inhibitory effect of calcitonin on osteoclast activity. The association of [67Ga]citrate with the nucleus of the osteoclasts is unique and different from tumor cells in which there is a high association of [67Ga]citrate with the lysosome fraction within the cytoplasm.
Autoradiography↗