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Biomedical subjects

F R Singer

Publications and source records attributed to F R Singer.

At least 37 records · Page 2Linked to original sources
PubMed1993

Biochemical assessment of bone formation and resorption in acromegaly.

The effects of chronic GH and insulin-like growth factor-I (IGF-I) excess on bone metabolism were examined by measuring serum markers of bone formation and urine markers of bone resorption as well as vertebral bone densities in patients with active acromegaly. Fasting serum GH levels were elevated in all 27 patients (31 +/- 11 micrograms/L). Serum calcium levels were within the normal range, except in 3 of 27 (10%) patients with mild hypercalcemia. Urinary calcium excretion, however, was increased in 6 (22%) patients despite mainly normal serum PTH and 1,25-dihydroxyvitamin D levels, suggesting a direct renal GH and/or IGF-I-mediated calciuric effect. Urinary hydroxyproline/creatinine excretion was increased in all except 1 patient and correlated with plasma IGF-I levels (r = 0.49; P < 0.02; n = 22). A more specific indicator of bone collagen turnover, urinary type I collagen cross-linked N-telopeptide, was elevated in all except 1 patient and correlated with serum GH (r = 0.47; P < 0.02), IGF-I (r = 0.60; P < 0.005), and urinary hydroxyproline/creatinine excretion (r = 0.62; P < 0.001). Serum bone Gla protein (osteocalcin), a specific marker of osteoblastic activity, was also increased in 50% of the patients and correlated with urinary N-telopeptide (r = 0.47; P < 0.02), but not with serum GH or IGF-I concentrations. Trabecular bone density, as determined by quantitative computerized tomography of the lumbar spine, was increased in only 1 patient; 13 others had subnormal bone density. The results suggest that in long-standing acromegaly, osteoblastic and osteoclastic activities are increased. Vertebral trabecular bone mass is usually reduced. Urinary collagen cross-links may serve as a more specific marker of bone resorption in acromegaly.

Acromegaly↗
PubMed1993

Giant cell tumor arising in Paget's disease of bone. Recurrences after 36 years.

A 96-year-old woman had both Paget's disease and a giant cell tumor of the same bone, the left scapula. Despite five surgical procedures, a full course of radiation therapy, and treatment with salmon calcitonin, human calcitonin, and finally disodium etidronate, the tumor has recurred over a 36-year period. The characteristic viral-like nuclear and cytoplasmic inclusions found in the osteoclasts of Paget's disease were found in the tumor giant cells, in specimens excised over an eight-year period, and in specimens obtained during orthopedic procedures on her other pagetic bone lesions over 12 years.

Aged↗
PubMed1992

A specific immunoassay for monitoring human bone resorption: quantitation of type I collagen cross-linked N-telopeptides in urine.

Peptides of low molecular weight that contain pyridinoline cross-links were isolated from adolescent human urine. A fraction was selected that was enriched in the N-telopeptide-to-helix intermolecular cross-linking domain of bone type I collagen. Mouse monoclonal antibodies were generated against these urinary peptides conjugated to a carrier protein as immunogen. A high-affinity antibody was identified that specifically bound to the trivalent peptides derived from the N-telopeptide-to-helix pyridinoline cross-linking site in type I collagen of human bone. This was confirmed by the direct isolation from human bone collagen of similar fragments recognized selectively by the antibody. A sensitive inhibition ELISA was established on microtiter plates that could quantify the bone-derived peptides in human urine. The assay, which can be run directly on untreated urine, was thoroughly tested against samples from normal subjects and from patients with metabolic bone disease. For example, strong correlations with urinary hydroxyproline and total pyridinoline cross-links were found in patients with Paget's disease of bone. The method shows considerable promise as a rapid and specific index of human bone resorption rates, with greatly improved specificity and convenience over total pyridinoline analysis. Potential applications include the study of normal metabolism, the diagnosis and monitoring of bone disease, and evaluating the effectiveness of antiresorption therapies.

Adolescent↗
PubMed1992

Effect of salmon calcitonin and etidronate on hypercalcemia of malignancy.

Hypercalcemia of malignancy is a commonly encountered serious clinical problem that often requires aggressive therapy. In order to combine the rapid hypocalcemic effects of calcitonin with the more delayed effect of a bisphosphonate, we administered etidronate, 7.5 mg/kg/day intravenously and salmon calcitonin, 100 IU subcutaneously, every 12 hours for 3 days in 9 patients with hypercalcemia associated with malignancy. The mean serum calcium concentration fell from 3.33 +/- 0.1 mmol/liter (mean +/- SEM) to 2.88 +/- 0.1 mmol/liter within 24 hours (P less than 0.001). All patients had a fall in the serum calcium concentration of greater than 0.5 mmol/liter and it returned to normal in 7 of the 9 patients. We conclude that the combination of salmon calcitonin with etidronate more effectively lowers the serum calcium concentration in patients with hypercalcemia of malignancy then the use of either agent alone.

Animals↗
PubMed1992

Interleukin 6. A potential autocrine/paracrine factor in Paget's disease of bone.

Pagetic osteoclasts are greatly increased in number and size and have increased numbers of nuclei per cell compared to normal osteoclasts. The mechanisms responsible for enhanced osteoclast formation in Paget's disease are unknown. We have used our recently described model system for pagetic osteoclast formation to evaluate culture media conditioned by these atypical multinucleated cells (MNC) to determine if pagetic osteoclasts produce an autocrine or paracrine factor that enhances osteoclast formation. Conditioned media from long-term bone marrow cultures from patients with Paget's disease stimulated osteoclast-like MNC formation in normal marrow cultures. At least part of this activity could be ascribed to interleukin 6 (IL-6). In contrast, conditioned media from normal marrow cultures contained lower levels of IL-6 and did not stimulate formation of osteoclast-like MNC. 7 of 8 bone marrow plasma samples taken from involved bones and 18 of 27 peripheral blood serum samples from Paget's patients had high levels of IL-6. Normal marrow plasma and peripheral blood serum had no or very low levels of IL-6. These results suggest that IL-6 produced by marrow and/or bone cells in patients with Paget's disease may be an autocrine/paracrine factor for pagetic osteoclasts.

Biological Assay↗
PubMed1992

Bone-resorption markers galactosyl hydroxylysine, pyridinium crosslinks, and hydroxyproline compared.

We compared the clinical performances of four bone-resorption (BR) assays (hydroxyproline, HYP; galactosyl hydroxylysine, GHYL; deoxypyridinoline, DPD; and pyridinoline, PYD) in subjects with different BR rates: normal (adult men and premenopausal women), mildly increased (postmenopausal osteoporotic women), high (Paget disease patients), and very high (children). The discrimination power (Z score) and the accuracy (estimated by receiver-operating characteristic analysis) for GHYL, DPD, and PYD were compared with those for HYP. Discrimination power and accuracy were similar for high- and very-high-BR groups for all four assays. However in the mildly increased-BR group, DPD, GHYL, and PYD showed a higher discrimination power and accuracy than did HYP. The clinical performances of HYP, DPD, GHYL, and PYD are comparable for large changes in BR. For modest changes, DPD, GHYL, and PYD are more accurate and have a higher discrimination power than does HYP.

Adult↗
PubMed1992

Osteopetrosis.

Explore the source record for details and available documents.

Bone Marrow Transplantation↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1990

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↗
PubMed1990

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↗
PubMed1990

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↗