Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0221002 (primary hyperparathyroidism)
 4,921 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We developed and validated a radioimmunoassay for circulating human parathyroid hormone-related peptide (PTHrP), based on a commercial antiserum to the synthetic 1-34 fragment of PTHrP, 125I-Tyr degrees-PTHrP(1-34) as radioligand, and prior extraction of the native peptide from plasma with C-2 cartridges. We determined immunoreactive PTHrP concentrations in plasma samples from 48 healthy persons (mean +/- SD, 3.1 +/- 1.0 pmol/liter; range, less than 2 to 5 pmol/liter), 8 patients with primary hyperparathyroidism, 36 patients with hypercalcemia and a concurrent malignant lesion, and 9 normocalcemic patients with cancer and increased serum levels of carcinoembryonic antigen or prostate-specific antigen. PTHrP was normal in samples from patients with primary hyperparathyroidism (3.2 +/- 1.1 pmol/liter), secondary hyperparathyroidism (2.5 +/- 1.3 pmol/liter), and cancer without hypercalcemia (2.4 +/- 1.0 pmol/liter). In contrast, plasma immunoreactive PTHrP levels were increased (6.0 to 85.0 pmol/liter) in 47% of patients with hypercalcemia and cancer of various types, with or without bone metastatic lesions. Large amounts of PTHrP were also found in conditioned medium from cultured human prostatic carcinoma cells. Thus, PTHrP may be a causative factor for hypercalcemia associated with a malignant lesion in at least half of the cases. Measurement of circulating PTHrP may be of differential diagnostic help in hypercalcemic states.
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PMID:Parathyroid hormone-related peptide in plasma of patients with hypercalcemia and malignant lesions. 223 3

We investigated the possible involvement of parathyroid hormone-related protein (PTHrP) in 2 cases of metastatic pancreatic neuro-endocrine tumors associated with severe hypercalcemia. Both patients displayed biochemical alterations in renal tubular reabsorption of calcium and phosphate, as well as in urinary cAMP excretion, similar to those encountered in primary hyperparathyroidism, although plasma levels of parathyroid hormone were within the normal range. Tumor protein extracts stimulated cAMP production, which was inhibited by the PTH-antagonist (8,18 Nle, 34 Tyr)bPTH-(3-34)amide, in the PTH-responsive osteoblastic cell line UMR-106. Northern blot analysis of tumor extracts revealed the presence of PTHrP mRNA transcripts, while PTH mRNA was undetectable. In contrast, neither PTHrP mRNA(s) nor cAMP-stimulating activity was detectable in other neuroendocrine tumors not accompanied by hypercalcemia. These results demonstrate that certain pancreatic neuroendocrine tumors associated with hypercalcemia can synthesize and release PTHrP.
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PMID:Parathyroid hormone-related protein and hypercalcemia in pancreatic neuro-endocrine tumors. 239 7

In order to obtain a better resolution of circulating PTH-fragments, we developed a radioimmunoassay with an antiserum raised against the synthetic 70-84 hPTH molecule in a sheep. [125I](69 Tyr) 70-84 hPTH was used as the radioactive tracer with the antiserum at a final dilution of 1:200 000. Displacement curves showed that only the 70-84 hPTH, (69 Tyr) 70-84 hPTH and 53-84 hPTH fragments were able to compete with the tracer. Synthetic 28-48 hPTH, 44-68 hPTH, (61 Tyr)62-68 hPTH, purified 1-84 hPTH and 53-84 bPTH showed no ability to displace the tracer indicating that the idiotype of the antibody is directed against the 70-84 portion that is usually hidden within the globular structure of the intact molecule. Healthy adults revealed PTH-peptide levels of 153 +/- 86 pg/ml (mean +/- 2 SD); 2 SD range: 67-239 pg/ml. C-terminal PTH-peptide (70-84 hPTH) concentration was normal in patients with primary hyperparathyroidism and chronic renal failure, thus excluding that neither the kidney nor the parathyroid gland is involved in the generation of this C-terminal PTH-peptide sequence. Increased levels of 70-84 hPTH immunoreactivity were found in most individuals with severe cholestatic liver disease. Since the liver appears to be responsible for part of the peripheral PTH metabolism, this assay system might be used as an indicator of altered liver function.
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PMID:Selective determination of C-terminal (70-84) hPTH: elevated concentrations in cholestatic liver disease. 394 4

We hereby present a rare variant of multiple endocrine neoplasia type 2A (MEN2A) associated with a rare skin disease primary cutaneous lichen amyloidosis and discrete malignant pheochromocytoma in both adrenal glands and pancreatic tail, and interestingly accompanied ganglioneuroma located in retroperitoneum in a 34-yr-old female. The presence of composite tumor of pheochromocytoma and ganglioneuroma arising in the adrenal glands has been described previously in MEN2A and in sporadic cases. The patient displayed classical signs and symptoms of catecholamine excess. Biochemical screening proved pheochromocytoma. Computed tomography revealed multiple mass lesions in both adrenal glands. It also showed a large heterogeneous mass that clearly discriminated from right adrenal gland in retroperitoneal location. After surgical exploration, both adrenal glands and the suspicious mass in pancreatic tail were removed successfully together with subtotal resection of the retroperitoneal tumor. Histopathologic examinations confirmed the presence of pheochromocytoma in both adrenal glands as well as pancreatic lesion. A retroperitoneal ganglioneuroma was also present. Symptomatic and biochemical evidence of pheochromocytoma subsided after the operation. Further evaluation for medullary thyroid carcinoma and primary hyperparathyroidism confirmed MEN2A. Mutation analysis of the ret proto-oncogene revealed a missense point mutation at position 634 in exon 11, which gives rise to the substitution of a cysteine codon with a tyrosine residue.
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PMID:Multiple endocrine neoplasia type 2A/localized cutaneous lichen amyloidosis associated with malignant pheochromocytoma and ganglioneuroma. 1627 70

Multiple endocrine neoplasia type 1 (MEN1) is characterized by parathyroid, enteropancreatic endocrine and pituitary adenomas as well as germline mutation of the MEN1 gene. We describe 2 families with MEN1 with novel mutations in the MEN1 gene. One family was of Turkish origin, and the index patient had primary hyperparathyroidism (PHPT) plus a prolactinoma; three relatives had PHPT only. The index patient in the second family was a 46-yr-old woman of Chinese origin living in Taiwan. This patient presented with a complaint of epigastric pain and watery diarrhea over the past 3 months, and had undergone subtotal parathyroidectomy and enucleation of pancreatic islet cell tumor about 10 yr before. There was also a prolactinoma. Sequence analysis of the MEN1 gene from leukocyte genomic DNA revealed heterozygous mutations in both probands. The Turkish patient and her affected relatives all had a heterozygous A to G transition at codon 557 (AAG-->GAG) of exon 10 of MEN1 that results in a replacement of lysine by glutamic acid. The Chinese index patient and one of her siblings had a heterozygous mutation at codon 418 of exon 9 (GAC-->TAT) that results in a substitution of aspartic acid by tyrosine. In conclusion, we have identified 2 novel missense mutations in the MEN1 gene.
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PMID:Two novel mutations in the MEN1 gene in subjects with multiple endocrine neoplasia-1. 1684 Aug 30

The cloning of the calcium sensing receptor (CaR) confirmed that parathyroid cells monitor extracellular calcium concentration ([Ca2+]ext) via a receptor-type mechanism. This lead to the hypothesis that abnormalities in the expression and/or function of the CaR could explain the biochemical abnormalities in primary hyperparathyroidism (PHPT). Cultured cells from parathyroid adenomas of patients operated for PHPT were used to monitor real-time changes in intracellular calcium concentration ([Ca2+]i) as measured by fluorescent microscopy using the Fura-2/AM dye. We found that CaR agonists trigger release of intracellular calcium pools and such responses are amplified by increasing the affinity of IP3 receptors. Using confocal microscopy to monitor membrane trafficking in living parathyroid cells labelled with the fluorescent dye FM1-43, we found that a decrease in [Ca2+]i rather than an absolute change in [Ca2+]ext is the main stimulus for exocytosis from human parathyroid cells. These data suggest that, in PHPT, a defective signalling mechanism from the CaR allows cells from parathyroid adenomas to maintain low [Ca2+]i with uninhibited PTH secretion in the face of hypercalcaemia. Over longer periods of time, CaR controls parathyroid proliferation via changes in tyrosine phosphorylation. We found that multiple proteins of molecular weight 20-65 kDa are phosphorylated within 10-60 min in response to CaR agonists. Further work demonstrated that high [Ca2+]i stimulates the expression of bcl-2 oncoprotein in cultured human parathyroid cells and that, in parathyroid adenomas, predominant expression of bcl-2 rather than bax oncoprotein might prevent apoptosis and explain the slow growth rate of these tumours. More recently, it became apparent that CaR stimulates cell proliferation in several cell types not involved in calcium homeostasis. Using archived histological material from 65 patients who died with metastatic breast cancer, we identified CaR expression predominantly in tumours from patients who developed bone rather than visceral metastases (35 of 49 versus 7 of 16; P < 0.01, chi-squared test). These data suggest that CaR expression has the potential to become a new biological marker predicting the risk of bone metastases in patients with breast cancer. A prospective study should investigate if patients with CaR-positive tumours are more likely to develop bone metastases and whether they could benefit more from prophylactic treatment with bisphosphonates or the newly developed CaR antagonists.
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PMID:The calcium sensing receptor: from understanding parathyroid calcium homeostasis to bone metastases. 1849 87

Preoperative localisation of the diseased parathyroid gland(s) in primary hyperparathyroidism (PHP) is a prerequisite for subsequent minimally invasive surgery. Recently, as alternatives to conventional sestamibi parathyroid scintigraphy, the (11)C-based positron emission tomography (PET) tracers methionine and choline have shown promise for this purpose. We evaluated the feasibility of using the (18)F-based PET tracer fluoroethyl-l-tyrosine (FET), as the longer half-life of (18)F makes it logistically more favourable. As a proof-of-concept study, we included two patients with PHP in which dual-isotope parathyroid subtraction single photon emission computed tomography had determined the exact location of the parathyroid adenoma. A dynamic FET PET/CT scan was performed with subsequent visual evaluation and calculation of target-to-background (TBR; parathyroid vs. thyroid). The maximum TBR in the two patients under study was achieved approximately 30 min after the injection of the tracer and was 1.5 and 1.7, respectively. This ratio was too small to allow for confident visualisation of the adenomas. FET PET/CT seems not feasible as a preoperative imaging modality in PHP.
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PMID:(18)F-FET-PET in Primary Hyperparathyroidism: A Pilot Study. 2754 29