Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gallium nitrate was recently found to be effective treatment for resistant cancer-related hypercalcemia. In vitro and in vivo experiments have suggested that the drug directly inhibits calcium resorption from bone; however, the overall effects of gallium nitrate on calcium balance were unknown. We have completed metabolic balance studies in four patients who received this drug by prolonged infusion. All patients were in positive calcium balance while receiving the drug. Each patient also showed a substantial decrease in urinary calcium excretion. Serum phosphorus decreased in all four patients. There was no change in phosphorus, sodium, chloride, or magnesium balance or in creatinine clearance. We conclude that prolonged infusions of gallium nitrate reduce urinary calcium excretion and that the hypocalcemic effect of this drug is primarily due to inhibition of calcium resorption from bone. Thus, the drug may prove useful in reducing accelerated bone resorption in patients with bone metastases or chronic cancer-related hypercalcemia.
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PMID:Metabolic effects of gallium nitrate administered by prolonged infusion. 401 69

Hypercalcemia of malignancy is most commonly due to the effects of parathyroid hormone-related peptide, which acts as a humoral factor to cause generalized osteoclast-mediated bone resorption and reabsorption of calcium by the kidney tubule, and may also act as a local resorptive factor adjacent to bone metastases. Local resorptive mechanisms are less common causes of malignant hypercalcemia than previously believed. Treatment begins with intravenous fluid rehydration, followed by a furosemide diuresis and the bisphosphonate pamidronate, 60-90 mg, intravenously. Gallium nitrate is an efficacious but inconvenient alternative to pamidronate. Calcitonin combined with pamidronate is a reasonable initial therapy for severe hypercalcemia to hasten normalization of the serum calcium. Steroids should be reserved for hypercalcemia due to tumor production of 1,25 dihydroxyvitamin D, or for steroid-responsive malignancies. Oral or parenteral bisphosphonates can be used to maintain normocalcemia. In addition to improving the morbidity of acute hypercalcemia, bisphosphonate therapy has been shown to reduce bone pain and pathological fractures in patients with bone metastases, and calcitonin also has a potent analgesic effect in these patients. Treatment for hypercalcemia should therefore be considered in the majority of patients in the palliative care setting.
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PMID:Hypercalcemia of malignancy in the palliative care patient: a treatment strategy. 754 27

An established rat hypercalcemia model was used to study the effects of gallium nitrate on elevated serum calcium levels. Gallium nitrate was administered by i.v. or i.p. injection at daily doses of 0.07-0.45 mmol/kg for 5 days to the hypercalcemic rats beginning 1 day following surgery. A dose-correlated normocalcemic response was observed. Gallium nitrate administered late after the induction of the hypercalcemic state was also effective in reducing serum calcium levels. The p.o. administration, however, even at doses as high as 0.45 mmol/kg, did not reduce serum calcium to normal levels. The values of area under the concentration versus time curve (0-24 h) of gallium in normal rats were comparable after i.v. [49.2 (micrograms/ml)h] or i.p. [57.0 (micrograms/ml)h] injections. In contrast, the p.o. route achieved only 15% bioavailability, which may explain the ineffectiveness of p.o. administered gallium nitrate at that dose level. This study suggests that daily i.v. bolus injections of gallium nitrate for managing hypercalcemia may be potentially as effective as the current regimen of continuous i.v. infusion.
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PMID:Normocalcemic effect of gallium nitrate in a hypercalcemic rat model. 781 63

Immunohistochemical and ultrastructural investigations of thyroid C cells were conducted in male nude (athymic) mice bearing a serially transplantable canine adenocarcinoma (CAC-8) model of humoral hypercalcemia of malignancy following subcutaneous administration of gallium nitrate. The following four groups were investigated: 1) vehicle-treated non-tumor-bearing control mice; 2) non-tumor-bearing mice treated with gallium nitrate; 3) vehicle-treated hypercalcemic mice bearing CAC-8; and 4) CAC-8 tumor-bearing mice treated with gallium nitrate. Gallium nitrate-treated tumor-bearing mice had a significant decrease in serum calcium as compared with tumor-bearing controls. C cells of non-tumor-bearing mice stained intensely for calcitonin and calcitonin gene-related peptide and weakly for chromogranin A and neuron-specific enolase. In C cells of both vehicle- and gallium-treated tumor-bearing mice, immunoreactive staining was decreased for calcitonin, calcitonin gene-related peptide, and chromogranin A, whereas there was a moderate increase in staining for neuron-specific enolase. Ultrastructurally, thyroid C cells in hypercalcemic tumor-bearing control and gallium-treated mice were hypertrophic and markedly degranulated as compared with those of non-tumor-bearing controls. Hypertrophic C cells contained few mature secretory granules, a well-developed Golgi apparatus, and lamellar arrays of rough endoplasmic reticulum. There was no evidence of C-cell hyperplasia. Immunohistochemical and ultrastructural findings revealed that C cells in mice with cancer-associated hypercalcemia were primarily in the actively synthesizing phase of the secretory cycle and had diminished immunoreactivity for calcitonin, calcitonin gene-related peptide, and chromogranin A.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of humoral hypercalcemia of malignancy and gallium nitrate on thyroid C cells in nude mice: immunohistochemical and ultrastructural investigations. 805 30

The principal pathophysiologic alteration in severe hypercalcemia accompanying hyperparathyroidism and malignancy is enhanced osteoclastic bone resorption. Hypercalcemia impairs renal mechanisms that lead to sodium and calcium excretion; PTH and PTHrP acting on renal tubules enhance further calcium reabsorption. Although rehydration is often necessary as an initial therapy of hypercalcemia, the cornerstone of therapy is to inhibit osteoclastic bone resorption. The bisphosphonates, plicamycin, gallium, and calcitonin all inhibit osteoclastic bone resorption. Calcitonin is the most rapidly acting agent. Toxicities of calcitonin are minimal, yet its therapeutic efficacy is limited by lack of potency and tachyphylaxis. The second-generation bisphosphonates such as pamidronate represent a class of compounds that are extremely effective in inhibiting the metabolic function of the osteoclast. Given in a single infusion, a significant majority of patients will have normalization of corrected serum calcium lasting, on average, 1-2 weeks. Therapeutic benefit will be of greater duration because most patients remain only minimally symptomatic until corrected serum calcium rises above 11.5 mg/dL. Side effects of low-grade fever, hypophosphatemia, hypomagnesemia, and hypocalcemia may occur. Gallium nitrate is a potent inhibitor of bone resorption and may be of increased clinical value when more efficient administration protocols can be developed. Plicamycin, available for two decades, has cumulative toxicities and is less potent than the aminobisphosphonates. Renal insufficiency often accompanies severe hypercalcemia. The nephrotoxicity of gallium nitrate and plicamycin should preclude their use when there is moderate impairment of renal function, and amino bisphosphonates become the treatment of choice in these patients. Although several authors have advocated individualized approaches to the management of hypercalcemia, the potency and duration of action of the aminobisphosphonates make them a reasonable treatment choice for most patients with symptomatic hypercalcemia. Most importantly, the most effective therapy for hypercalcemia is to recognize and treat the underlying disease. Acute primary hyperparathyroidism requires surgery. The effective treatment of hypercalcemia of malignancy allows the introduction of tumor-specific therapy, limits morbidity, and shortens and deintensifies hospitalization. At times, the most appropriate and compassionate decision (particularly in patients with malignancy who have exhausted all therapeutic options and have relentless bone pain) is to withhold therapy for hypercalcemia. Future therapies directed at the osteoclast, such as more potent later-generation bisphosphonates; inhibitors of osteoclast attachments and inhibitors of peptides, which stimulate osteoclastic bone resorption, may permit safe, easily administered, outpatient therapies that will improve the quality of life for hypercalcemic patients.
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PMID:Pathophysiology and management of severe hypercalcemia. 832 91

Gallium nitrate, a group IIIa metal salt, has been found to be clinically effective for the treatment of accelerated bone resorption in cancer-related hypercalcemia and Paget's disease. Here we report the effects of gallium nitrate on osteocalcin mRNA and protein levels on the rat osteoblast-like cell line ROS 17/2.8. Gallium nitrate reduced both constitutive and vitamin D3-stimulated osteocalcin protein levels in culture medium by one-half and osteocalcin mRNA levels to one-third to one-tenth of control. Gallium nitrate also inhibited vitamin D3 stimulation of osteocalcin and osteopontin mRNA levels but did not affect constitutive osteopontin mRNA levels. Among several different metals examined, gallium was unique in its ability to reduce osteocalcin mRNA levels without decreasing levels of other mRNAs synthesized by ROS 17/2.8 cells. The effects of gallium nitrate on osteocalcin mRNA and protein synthesis mimic those seen when ROS 17/2.8 cells are exposed to transforming growth factor beta 1 (TGF beta 1); however, TGF-beta 1 was not detected in gallium nitrate-treated ROS 17/2.8 cell media. Use of the RNA polymerase II inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole demonstrated that gallium nitrate did not alter the stability of osteocalcin mRNA. Transient transfection assays using the rat osteocalcin promoter linked to the bacterial reporter gene chloramphenicol acetyltransferase indicated that gallium nitrate blocked reporter gene expression stimulated by the osteocalcin promoter. This is the first reported effect of gallium nitrate on isolated osteoblast cells.
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PMID:Gallium nitrate regulates rat osteoblast expression of osteocalcin protein and mRNA levels. 838 Dec 50

Recent information on the pathophysiology and treatment of hypercalcemia of malignancy is reviewed, and the roles of two new agents, gallium nitrate and pamidronate, are discussed. Current evidence suggests that parathyroid hormone-related protein is the most important mediator of humoral hypercalcemia of malignancy. In patients with local osteolytic hypercalcemia, cytokines have been implicated as mediators. Effective treatment of hypercalcemia of malignancy may improve patients' quality of life, although an episode of hypercalcemia is a poor prognostic indicator for survival. Gallium nitrate is more effective than salmon calcitonin and possibly more effective than etidronate in the treatment of hypercalcemia of malignancy. The primary adverse effect of gallium nitrate is nephrotoxicity, and its use must be avoided in patients who have renal dysfunction or who are receiving nephrotoxic drugs. Pamidronate is more effective than etidronate in the treatment of hypercalcemia of malignancy and can be administered as a single i.v. dose. The adverse effects of pamidronate include mild fever, hypocalcemia, and hypophosphatemia. Compared with gallium nitrate, pamidronate offers a more convenient dosing regimen, is less frequently associated with nephrotoxicity, and is less expensive. Single i.v. doses of either pamidronate or plicamycin effectively lower serum calcium levels and are reasonable choices for maintenance therapy. Gallium nitrate and pamidronate may be slightly more effective than previously available agents for initial treatment of hypercalcemia. Pamidronate currently offers the best combination of effectiveness, ease of administration, and a low rate of adverse effects.
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PMID:Update on the medical treatment of hypercalcemia of malignancy. 845 60

Hypercalcaemia is the most common metabolic complication of malignant disease. It is an important cause of morbidity in cancer patients and is potentially amendable to treatment. Bone metastases are rarely the cause of hypercalcaemia in malignancy, the elevation in calcium concentrations usually resulting from the effects of humoral mediators released by the tumour. Many factors isolated from tumours have the potential to cause hypercalcaemia, but the most important is parathyroid hormone related protein (PTHrP), a peptide which mimics the effect of PTH. Treatment of cancer associated hypercalcaemia is based on an initial phase of volume repletion with isotonic saline, followed by drug treatment to inhibit bone resorption. Bisphosphonates are the most widely used agents in the treatment of such bone resorption, are very effective and have minimal toxicity. Gallium nitrate is also effective but less widely used. The combination of bisphosphonates and calcitonin has been found to be particularly useful in patients with severe hypercalcaemia, since this gives a more rapid reduction in serum calcium values than can be achieved with bisphosphonate alone. In the longer term, effective control of hypercalcaemia depends on treating the primary tumour. In the majority of cases this is not possible, however, because of the state of disease progression or the nature of the tumour. Anti-hypercalcaemic therapy is an important palliative measure in cancer patients who have symptoms of hypercalcaemia. Treatment does little to alter the long term prognosis but often results in an improvement in symptoms such that the majority may be made well enough to be discharged from hospital care.
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PMID:Pathogenesis and management of cancer associated hypercalcaemia. 856 93

Gallium nitrate was originally developed as an antineoplastic agent; however, further studies have revealed that this drug has extremely potent effects on turnover of bone, and that low doses can be used to reduce bone resorption. Like the bisphosphonates, gallium nitrate has been studied in both malignant and in nonmalignant conditions. The results of randomized double blind studies have suggested that this drug has superior clinical efficacy relative to etidronate, calcitonin, and pamidronate for the acute control of cancer-related hypercalcemia. In patients with Paget's disease, low doses of gallium nitrate reduce biochemical parameters of accelerated bone turnover, including urinary excretion of calcium, hydroxyproline, and urinary collagen cross-linked N-telopeptides. Preliminary studies showed similar effects in patients with bone involvement from a wide variety of tumor types. Based on this high degree of clinical potency revealed in clinical studies, two randomized Phase III studies have been initiated in patients with bone metastases from breast carcinoma and bone involvement due to multiple myeloma. Both studies employ cyclic therapy with low dose gallium nitrate (i.e., 40 mg administered as a subcutaneous injection once daily for 2 weeks, followed by 2 weeks off treatment, recycled monthly). The endpoints of both studies are to document reductions in time to "morbid skeletal events," such as palliative skeletal radiotherapy, stabilizing orthopedic surgery, or pathologic fractures, as well as decreases in pain and analgesic requirements and improvements in mobility and other aspects of quality of life. These trials should provide definitive evidence of whether this agent is safe and effective as a treatment for bone metastases.
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PMID:Gallium nitrate for the treatment of bone metastases. 936 36

Gallium nitrate, an approved antitumor drug, has found clinical application in the treatment of cancer-related hypercalcemia and of Paget's disease; the exact mechanism of its action, however, remains unknown. The present study utilized rats in a 7-day exposure to gallium at doses similar to those used clinically. Quantitative histomorphometry and ultrastructural examination of osteoclast fine structure were carried out on specimens from animals with documented hypocalcemia. Gallium exposure produced striking changes in the osteoclast. The number of nuclei/osteoclast increased, and the ruffled borders of the osteoclasts were markedly decreased along the length of the Howship's lacunar cavity. The absence of a decrease in osteoclast number and the types of changes seen in ultrastructure suggest that the mechanism of action of gallium seen here may differ from that of calcitonin, a nontoxic, reversible antiresorbing agent. Results underscore the difficulty in assessing the toxicity of agents such as gallium on the osteoclast, a mature differentiated cell which does not divide and which does not produce a characteristic extracellular matrix component.
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PMID:In vivo morphologic changes in the rat osteoclast induced by gallium nitrate: the result of toxicity or other effects? 1043 97


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