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Results for “Parathyroid Neoplasms”

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At least 811 records · Page 45Linked to original sources
PubMed1985

The two-hit theory of neoplasia: implications for the pathogenesis of hyperparathyroidism.

Knudson's two-hit or two-mutational-event hypothesis for the initiation of neoplasia suggests that two somatic mutations are necessary for initiation of sporadic neoplasms, and that a genetic plus a somatic mutation are required for hereditary neoplasms. Glucose-6-phosphate dehydrogenase (G6PD) studies of parathyroid tumors of 11 heterozygotes with hyperparathyroidism (HPT), including one with hereditary HPT, have shown both A and B isoenzymes. These findings suggest multicellular development of parathyroid tumors and are compatible with tumors being manifestations of either nonneoplastic hyperplasia or a genetic first mutational event. Parathyroid carcinoma may be the result of a second mutation in cells made susceptible by previous genetic or somatic mutations. Comparison of parathyroid cancer in families with hereditary HPT with sporadic cases from the literature reveals a generally younger onset with hereditary HPT compatible with the two-hit theory. Consideration of these age-of-onset and G6PD findings suggest that hyperparathyroidism may result from either non-neoplastic or mutational-induced processes even though no histologic distinctions have been observed in the hyperplasia associated with these processes.

Glucosephosphate Dehydrogenase↗
PubMed2006

PTHrP, calcitonin and calcitriol in a case of severe, protracted and refractory hypercalcemia due to a pancreatic neuroendocrine tumor.

A patient with a primary neuroendocrine tumor of the pancreas, presented with severe hypercalcemia. This hypercalcemia of malignancy (HCM) failed to respond to intensive bisphosphonate treatment and needed continuous enhanced diuresis. Only after successful antitumor therapy did the hypercalcemia subside. Hypercalcemia was associated with increased concentrations of plasma PTHrP, calcitonin and 1,25-(OH)(2)D(3). Bone mineral density was markedly increased. We demonstrated the presence of both PTHrP and calcitonin in the tumor at the mRNA and protein level, using RT-PCR, immunohistochemistry and Western blotting. The high levels of plasma PTHrP and the demonstrated predominant renal mechanism in this case of HCM are suspected to be the cause for its refractoriness to bone resorption inhibitors. Our findings furthermore suggest that the tumoral production of calcitonin and PTHrP might have contributed to the increased bone mineral storage of calcium and thus probably attenuated the development of frank hypercalcemia.

Base Sequence↗
PubMed2000

[Surgery for primary hyperparathyroidism in 1998. Apropos of 66 patients and 3 methods of approach].

STUDY AIM: The aim of this prospective study was to assess the advantages and disadvantages of cervicotomy, selective lateral approach and video-assisted surgery in the treatment of primary hyperparathyroidism (HPT 1). PATIENTS AND METHODS: During 1998, 66 patients were operated on for HPT 1 in the same center. There were 48 women and 18 men (mean age: 58 years, range: 21-84), familial HPT 1 or MEN1 excluded. The interventions were performed via classical cervicotomy (n = 32), via selective lateral approach (n = 8) and were video-assisted (n = 25). A mediastinal adenoma was removed via cervicotomy and another one via left thoracoscopy. The procedure was associated with intraoperative parathormone (PTH) quick-assay. Calcium testing was controlled before leaving the hospital and 2 months later. RESULTS: A double adenoma and 65 single adenomas were confirmed by pathological report. Circulating PTH levels, 20 minutes after removal of the adenoma, always decreased significantly. In video-assisted procedures, there were 11 conversions to open cervicotomy (44%) and morbidity consisted of one case of laryngeal nerve paralysis. At the end of the study, all patients except one had a normal calcium level. CONCLUSION: Video-assisted parathyroidectomy is feasible but requires a preoperative localisation of the adenoma and intraoperative PTH quick-assay. Its main benefit in cervical adenoma is to reduce the scar and in mediastinal adenoma to avoid sternotomy. With the elective approach, results are similar to those of video-assisted surgery and the procedure is much easier to perform. Classical cervicotomy is still the best option in case of previous cervicotomy, of simultaneous thyroidectomy, of negative preoperative imaging and in elderly patients less concerned about cosmetic benefit.

Adenoma↗
PubMed1986

Primary anterior mediastinal tumors in children and adults.

This review details pertinent anatomical, radiological, pathological, and clinical information regarding primary anterior mediastinal tumors. Although the majority of these lesions are included in one of several subgroups, for example, thymic tumors, teratomas, or thyroid abnormalities, other less common entities will occasionally be encountered by the practicing surgeon. Likewise, there are variations in the frequency distribution of anterior mediastinal lesions in children as opposed to adults. Management of these individual lesions is outlined.

Adult↗
PubMed1984

High-resolution real-time sonography. The study of superficial body parts.

High-resolution real-time scanning such as described in this article remains limited to the very superficial areas of the body. This article has been designed to give the reader an up-to-date glimpse of the minute world of small parts scanning and aid the clinician in the optimal use of this noninvasive modality.

Biopsy, Needle↗
PubMed1978

Common precursor molecule as origin for the ectopic-hormone-producing-tumour syndrome.

When messenger R.N.A. (m-R.N.A.) extracted from various hormone-secreting tumours was injected into Xenopus eggs, the translation products in all cases proved to be a protein of molecular weight 65 00. Analysis by polyacrylamide-gel electrophoresis and specific precipitation reactions with antibodies showed a striking similarity between the various proteins. When translation products of m-R.N.A. from calcitonin-secreting medullary thyroid carcinoma (M.T.C( and the non-secreting anaplastic form of M.T.C. were incubating with specific enzyme systems (the microsomal fraction) from both types of tumour, enzymes from anaplastic M.T.C. had no effect on the translation products, whereas enzymes from differentiated M.T.C. degraded the translation products from both differentiated and anaplastic M.T.C. The results support the hypothesis that the primary gene product of all the different types of carcinoma cell studied is a single large protein (a hormone precursor or prohormone) containing different specificities. The specific enzyme system in each carcinoma cell probably selects the specific hormone liberated from this primary protein.

Adenocarcinoma↗
PubMed2006

Circulating PTH molecular forms: what we know and what we don't.

Circulating parathyroid hormone (PTH) molecular forms have been identified by three generations of PTH assays after gel chromatography or high-performance liquid chromatography fractionation of serum. Carboxyl-terminal (C) fragments missing the amino-terminal (N) structure of PTH(1-84) were identified first. They represent 80% of circulating PTH in normal individuals and up to 95% in renal failure patients. They are regulated by calcium (Ca) slightly differently than PTH(1-84), occurring in a relatively smaller proportion relative to the latter in hypocalcemia but in a much larger proportion in hypercalcemia. Synthetic C-PTH fragments do not bind to the PTH/PTHrP type I receptor and are not implicated in the classical biological effect of PTH(1-84). They bind to a different C-PTH receptor and exert biological actions on bone that are opposite to those of PTH(1-84). The integrity of the distal C-structure appears to be important for these biological effects, and it is uncertain if all C-PTH fragments are intact up to position 84. A second category of C-PTH fragment has a partially preserved N-structure. They are called non-(1-84) PTH or N-truncated fragments. They react in Intact (I)-PTH assays but not in PTH assays with a 1-4 epitope. They are acutely regulated by Ca(2+) concentration. They also exert similar hypocalcemic and antiresorptive effects but have 10-fold greater affinity for the C-PTH receptor compared to other C-PTH fragments. Even if they represent only 10% of all C-PTH fragments, they could be as relevant biologically. An N form of PTH other than PTH(1-84) has been identified in the circulation. It reacts very well in PTH assays with a 1-4 epitope but poorly in I-PTH assay with a 12-18 epitope. It is oversecreted in severe primary and secondary hyperparathyroidism and in parathyroid cancers. Its biological activity is still unknown. Overall, these studies suggest that PTH(1-84) and C-PTH fragments are regulated differently to exert opposite biological effects on bone via two different receptors. This may serve to control bone turnover and Ca concentration more efficiently.

Animals↗
PubMed1999

Tumor-related osteomalacia followed after treatment by hyperparathyroidism.

Tumor-induced osteomalacia is due to renal phosphate wasting in response to a humoral factor produced by a tumor, usually a benign mesenchymal tumor. Removal of the tumor is followed by resolution of the metabolic disorder. Physicians should be aware that sporadic renal phosphate wasting in an adult should prompt a search for a tumor. A case of tumor-induced osteomalacia due to a nonossifying fibroma of the radius is reported. After removal of the tumor, renal phosphate excretion returned to normal, but the patient developed tertiary hyperparathyroidism. Eight years elapsed between symptom onset and the diagnosis of the tumor. The pathogenesis of tumor-induced osteomalacia and the role of treatment for renal phosphate wasting on the subsequent development of hyperthyroidism are discussed.

Adenoma↗