Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report here an unusual case of association between thyrotropin (TSH)-secreting pituitary adenoma and papillary thyroid carcinoma in a young female patient. Serum TSH levels did not significantly change after both stimulatory (thyrotropin-releasing hormone [TRH], domperidone) and inhibitory (bromocriptine levotriiodothyronine, [LT3], levothyroxine [LT4], LT4 plus LT3) tests, while a 67% decrease of serum TSH levels was obtained after acute administration of a somatostatin analog (SMS 201-995, 100 microg s.c.). Serum alpha-subunit levels and the alpha-subunit/TSH molar ratio were clearly elevated. Magnetic resonance imaging (MRI) revealed the presence of a pituitary adenoma (1 cm in diameter). Pitfalls arising from the failure to inhibit TSH secretion in a patient thyroidectomized for papillary cancer are discussed.
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PMID:Unusual association between a thyrotropin-secreting pituitary adenoma and a papillary thyroid carcinoma. 951 Jan 28

Thyroid-stimulating hormone (TSH) secreting pituitary adenoma is a rare but important cause of thyrotoxicosis. It poses a challenge for both diagnosis and management. We report the case of a young Chinese man presenting with thyrotoxicosis, complicated by congestive heart failure, secondary to a TSH secreting pituitary adenoma. The case illustrates the importance of prompt diagnosis and allows discussion of both medical and surgical management, including the use of a long-acting somatostatin analogue.
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PMID:TSH secreting pituitary adenoma: a rare cause of thyrotoxicosis. 953 75

The authors detected in a 30-year-old patient a very rare type of hyperthyroidism caused by a thyrotropin secreting pituitary adenoma. Scintigraphic examination of the pituitary by means of 111In radiolabelled octreotide revealed an increased accumulation of the radiopharmaceutical preparation in the tumour, which confirmed the high density of somatostatin receptors. After onset of octreotide treatment (Sandostatin, Sandoz, Switzerland) 3 x 100 ug/day by the s.c. route a brisk decline and normalization of thyrotropin already after the first dose was recorded. The thyroxine concentration declined slowly to the upper range of normal values. After 5 months treatment despite the positive response to receptor scintigraphy diminution of the adenoma was not recorded. Again an increase of thyrotropin above the upper limit of the reference range and a marked rise of thyroxinaemia were observed. Six months after radical selective trans-sphenoidal adenomectomy normal pituitary function was confirmed.
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PMID:[Octreotide in the treatment of thyrotropin-secreting pituitary adenomas]. 975 Apr 71

Thyrotropin secreting pituitary adenomas are scarce. They may cause an extremely rare form of hyperthyroidism. The diagnosis is often delayed because the clinical symptoms are attributed to common types of hyperthyroidism. The diagnosis involves detection of elevated or normal (unsuppressed) thyrotropin levels in hyperthyroid patients and evidence of a pituitary adenoma by computed tomography or magnetic resonance imaging. The thyrotropin response in the thyrotropin-releasing hormone test is either absent or insufficient. When the pituitary microadenoma appears to be undetectable, the familiar syndrome of selective pituitary resistance to thyroid hormones has to be excluded. Treatment involves extirpation of the tumour. If the macroadenoma is not removed completely, external radiotherapy of the pituitary follows. If this conventional treatment does not produce an adequate effect, treatment with long-acting somatostatin analogues is recommended.
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PMID:[Thyrotropin-secreting adenomas of the hypophysis]. 975 Apr 72

Thyrotropin (TSH)-secreting pituitary adenomas are the less frequent form of presentation of pituitary tumors. Selective transsphenoidal surgical resection of the tumor is the treatment of choice. Given that native somatostatin inhibits TSH secretion, treatment with somatostatin analogues has been recently employed in patients with unresectable tumors or after surgery. We report on the case of a 58 year-old man with a TSH-secreting pituitary adenoma who was treated with octreotide for long-term before neurosurgery. The patient was referred to us because of a pituitary mass on CT scanning. Hormonal evaluation resulted in hyperthyroidism with high serum TSH concentrations. Serum alpha subunit concentration was elevated and TSH response to exogenous TRH stimulation was absent. Magnetic resonance imaging of the hypothalamic-pituitary area confirmed the presence of a pituitary mass (2.0 by 1.8 by 1.7 cm). Acutely administered subcutaneous octreotide (100 microg) was followed by a reduction of the serum TSH concentrations. Therefore, the patient received octreotide, 100 microg three times daily for 12 months. At first month after beginning therapy serum TSH, free thyroxine, total triiodothyronine, and alpha subunit concentrations were normalized and persisted into the normal range for the next 11 months. On the other hand, a shrinkage of the tumor mass (1.6 by 1.7 by 1.4 cm) was noted after 6 months of octreotide therapy, however, its volume did not modify in the following next months. Then, the tumor was removed by transsphenoidal surgery and the diagnosis was confirmed by immunohistochemical staining. This case demonstrates that long-term treatment with octreotide gave rise to a normalization of the thyroid function and a reduction of the tumor volume before surgery. This clinical observation suggests that octreotide therapy might be useful in preparation for pituitary surgery in patients with TSH-secreting pituitary adenomas.
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PMID:Long-term preoperative management of thyrotropin-secreting pituitary adenoma with octreotide. 997 79

The authors present clinical features, diagnostic approach and treatment of inappropriate TSH secretion syndrome. To data above 80 cases of this syndrome have been described. The main clinical features are thyrotoxicosis and vascular goiter present in the patient with pituitary adenoma. High concentrations of free thyroid hormones coexist with elevated TSH serum level. In some cases hyperproduction of other anterior lobe pituitary hormones was found. The molar ratio alpha subunit to TSH exceeds 1.0. In the management of inappropriate TSH secretion syndrome hypophysectomy, irradiation and long-acting somatostatin analog octreotide are applied.
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PMID:[The syndrome of inappropriate TSH secretion of neoplastic origin (NIST)]. 1010 68

Chimeric peptides consisting of growth hormone releasing peptide (GHRP-6) linked to somatostatin (6-11) via an amide bond to provide the effector parts of both the peptides were synthesized. The anti-proliferative, cytotoxic, and GH-inhibitory activities of these chimeric peptides were determined in vitro in the rat pituitary adenoma cell line GH3. One of the chimeric peptides, GSD, exhibited significantly greater (p < 0.001) anti-neoplastic and GH-inhibitory activity, as compared to RC-160. The hybrid peptides displayed high affinity binding to somatostatin receptors on GH3 cells. The bioactivity of GSD was found to be mediated by the stimulation of tyrosine phosphatase, involving a cGMP-dependent pathway, through pertussis toxin-sensitive G-proteins. Such potent GH-inhibitory chimeric peptides may be of potential importance in the therapy of acromegaly, as well as provide novel tools to study the regulation of GH secretion by GHRP and somatostatin.
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PMID:Antiproliferative and GH-inhibitory activity of chimeric peptides consisting of GHRP-6 and somatostatin. 1036 18

A 41-year-old male presented with progressive visual defects, acromegaly and hyperthyroidism. After clinical evaluation a giant GH/TSH-secreting pituitary adenoma was diagnosed. Administration of the somatostatin analog octreotide at doses of 150 microg s.c. per day inhibited the secretion of both GH and TSH. A three-week treatment with octreotide prior to surgery led to slight visual improvement and CT scan showed some new necrotic areas within the tumor mass. Transcranial surgery was performed. By immunohistochemical analyses of the adenoma tissue GH, prolactin and beta-chorionic gonadotropin were detected; TSH was negative. Electron microscopy revealed an undifferentiated, monomorphous adenoma with morphological features of an acidophil stem cell adenoma such as the presence of misplaced exocytoses, fibrous bodies and mitochondrial gigantism. However, the tumor cells contained small secretory granules (up to 250 nm) accumulated along the cell membrane characteristic of thyrotrope cells. Furthermore, some adenoma cells were fusiform with long cytoplasmic processes resembling thyrotropes. Two months after the operation CT scan revealed a large residual tumor. Serum GH and TSH levels had increased again and the TSH level was even higher than before the treatment. The patient died suddenly, most probably of lethal arrhythmia. Specimens of the adenoma tissue obtained at autopsy confirmed the previous findings with the exception of positive immunostaining for TSH which was found in less than 1% of the adenoma cells. This undifferentiated, monomorphous GH/TSH-secreting pituitary adenoma represents an entity that is unusual both in its ultrastructural features and clinical manifestations suggesting a cytogenesis from an early, undifferentiated stem cell.
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PMID:Clinical and morphological features of undifferentiated monomorphous GH/TSH-secreting pituitary adenoma. 1036 9

Five hyperthyroid patients with TSH-secreting pituitary adenoma were treated with octreotide. Acute administration of octreotide decreased plasma TSH levels in all patients (mean decrease, 50.6 +/- 14%). Treatment with octreotide (25-300 microg/day) for 2-360 weeks resulted in reductions in plasma TSH and alpha-subunit levels in three patients, and serum free thyroxine levels were normalized with concomitant clinical improvements such as disappearance of excessive sweating, tachycardia and finger tremors. In two patients, plasma TSH and free thyroxine levels were initially decreased, but tachyphylaxis occurred 3 and 10 weeks after the initiation of therapy. Mild to marked shrinkage of the tumor was observed 2-50 weeks later in four patients. Shrinkage of the tumor seems to be reversible in one case. Frequent bowel movements and epigastric discomfort occurred in two patient. Somatostatin receptor subtype 2 (sst2) mRNAs were detected in two adenoma tissues studied by RT-PCR. Long-term treatment with octreotide is effective in controlling hyperthyroidism and tumor growth in patients with TSH-secreting pituitary adenoma.
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PMID:Treatment of thyrotropin-secreting pituitary adenomas with octreotide. 1042 75

Technetium 99m P829 (99mTc P829) is a somatostatin like structure labelled with Technetium-99m. Somatostatin receptor positive tumors such as pituitary tumors, neuroendocrine tumors, and lymphomas show positive scintigraphy. Eleven patients suspected of having a pituitary mass (12 studies) were studied with 99mTc P829. Three pituitary adenoma patients (4 studies) showed positive somatostatin receptor tumor imaging. Eight negative somatostatin receptor scintigraphy were one hypothyroid induced pituitary hyperplasia, one craniopharyngioma, one normal pituitary tissue with focal hyperplasia, one ACTH secreting pituitary tumor, one GH, PRL secreting pituitary tumor post transphenoidal partial tumor removal, and no surgery in 3 patients. Finally, somatostatin receptor imaging may be useful as a tumor localizing technique in addition to conventional CT and MRI imaging and identify patients who might potentially benefit from octreotide treatment. In addition, the development of peptide analogs coupling to beta-emitting radiopharmaceutical may lead to a situation in which diagnosis peptide receptor scintigraphy can be followed by radionuclide therapy.
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PMID:Somatostatin receptor tumor imaging (Tc 99m P829) in pituitary adenoma. 1065 62


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