Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcitonin is now a well-accepted therapy for inhibition of bone loss, both in the first years of menopause and in established osteoporosis. However, its exact role in the pathogenesis of that disease as well as the interactions between calcitonin production and estrogen metabolism remain unsolved. In order to clarify the influence of estrogen replacement therapy (ERT) on calcitonin secretory capacity, we measured whole plasma immunoreactive calcitonin basal levels, metabolic clearance rates and production rates in a group of postmenopausal women, before and after a daily intake for 28 days of 0.625 mg/day of conjugated equine estrogens, and again 4 weeks after the withdrawal of that estrogen replacement therapy. No significant changes appeared in immunoreactive calcitonin or immunoreactive calcitonin metabolic clearance rate but the production rate significantly increased over the 28 days (mean +/- SEM, from 21.3 +/- 5.1 pg/ml to 25.2 +/- 5.9 pg/ml, p less than 0.05), and then decreased 4 weeks after therapy was withdrawn to the initial level (17.9 +/- 3.6 pg/ml). We concluded that estrogen replacement therapy significantly increases calcitonin secretory capacity. This confirms the interactions between calcitonin production and estrogen metabolism, and may provide an explanation concerning the mode of action of estrogen replacement therapy in prevention of postmenopausal bone loss.
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PMID:Influence of estrogen replacement therapy on endogenous calcitonin production rates. 158 Jan 70

Calcitonin has an uncertain role in the preservation of bone mass. Since surgical thyroidectomy abolishes the calcitonin secretion in response to calcium, the bone mineral density at the radius shaft and lumbar spine was measured in 60 patients (5 men, 16 premenopausal, 34 postmenopausal euparathyroid and 5 postmenopausal hypoparathyroid women) who had undergone near total thyroidectomy for thyroid cancer 8.4 +/- 0.7 years before the study. All patients were maintained on suppressive doses of thyroid hormones. Bone mineral density values of the radius shaft (expressed as Z-score) of 34 postmenopausal euparathyroid women was significantly below the normal average (mean +/- SEM = -0.59 +/- 0.2; p = 0.01). Bone mineral density of the lumbar spine was also below the normal average although the difference only approached statistical significance (-0.36 +/- 0.2; 0.05 less than p less than 0.1). The bone mineral density of neither the radius nor the spine differed from normal levels in the premenopausal women and the postmenopausal hypoparathyroid women. Unexpectedly, the bone mineral density of the spine was significantly increased in the 5 thyroidectomized men. The results indicate that thyroidectomized women have a diminished bone mass after the menopause only if parathyroid function is normal. Since the patients were receiving thyroid hormone at suppressive doses, the present study is not able to separate the relative contributions of calcitonin deficit and exogenous thyroid on bone mass loss.
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PMID:Bone mass in totally thyroidectomized patients. Role of calcitonin deficiency and exogenous thyroid treatment. 202 10

Calcitonin (CT) deficiency and its possible repercussions on bone mass were studied in a group of 9 adult patients (7 females, 2 males) with congenital hypothyroidism of dysgenetic origin. Using a new extraction method (exCT) which considerably improves the sensitivity and the specificity of the assay for CT-monomer, we measured CT levels before and after a short calcium (Ca) stimulation test (2 mg Ca/kg over 5 minutes) to evaluate C-cell secretory reserve. Mean basal plasma CT concentrations were lower in the hypothyroid women (mean +/- SEM: 0.6 +/- 0.1 pg/ml) than in 30 normal female controls (1.7 +/- 0.2 pg/ml, P less than 0.001). Serum calcium increased similarly in the two groups, but postinfusion CT levels were lower in the hypothyroid women, (1.7 +/- 0.2 pg/ml) than in normal women (16.8 +/- 2.9 pg/ml), P less than 0.001. Hypothyroid women showed a 10% reduction in bone mineral content at the diaphyseal site in the radius, 0.840 +/- 0.037 g/cm, compared with normal age-matched controls, 0.930 +/- 0.020 g/cm, (P less than 0.05). Our study demonstrates the existence of a profound CT-monomer deficiency in adult patients with thyroid agenesis or dysgenesis. Both calcitonin deficiency and thyroid hormone treatment could play a role in the observed bone loss. Attention should therefore be paid to bone metabolism during treatment of congenital hypothyroidism to avoid further bone loss.
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PMID:Calcitonin and bone mass status in congenital hypothyroidism. 193 88

In a double-blind placebo-controlled study, we examined the effect of calcitonin on gastric emptying, and on serum concentrations of gastrin, insulin, glucose, calcium, and phosphorus after a mixed solid-liquid meal in 11 healthy men. Synthetic salmon calcitonin was administered as a 415 pmol i.v. bolus injection followed by a 90-min infusion to reach an overall dose of 62.25 pmol/kg body mass. Gastric emptying of a radiolabeled meal was surveyed by means of a gamma camera. A pronounced inhibition of gastric emptying with calcitonin was observed in all subjects (median gastric half emptying time 60.3 min after placebo versus 197.6 min after calcitonin; p less than 0.001). Calcitonin did not effect the postprandial gastrin release, nor did it change significantly the serum calcium or phosphorus concentrations. A decreased postprandial insulin release by calcitonin (mean +/- SEM area under the insulin curve 2,124.6 +/- 382.0 min mU L-1 after placebo versus 640.9 +/- 124.0 min mU L-1 after calcitonin; p less than 0.002) was accompanied by a different pattern of serum glucose concentrations during the infusion of the hormone when compared to the situation with a placebo. We discuss potential mechanisms and clinical relevance of our findings.
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PMID:Effect of calcitonin on gastric emptying and on serum insulin and gastrin concentrations after ingestion of a mixed solid-liquid meal in humans. 240 30

Calcitonin (CT) is a 32 amino acidic polypeptide hormone which has been found in almost all species and whose effects are mainly concerned with calcium and phosphorous homeostasis. Three preparations are employed for therapeutic uses: salmon (sCT), porcine (pCT) and human CT (hCT). The sCT is the most powerful one and in human volunteers a strong relaxing effect has been shown on gallbladder (GB) basal volume and emptying in response to a meal, intraduodenal instillation of a liquid meal and i.v. cholecystokinin (CCK) infusion. Our study was aimed at investigating if a direct sCT effect could be demonstrated on smooth muscle strips from guinea pig GBs "in vitro" (organ bath). Isometric contractions were measured in response to maximal doses of acetylcholine (ACh: 10(-4) M), KCl (80 mM) and cholecystokinin octapeptide (CCK-OP: 10(-6) M), in absence and in presence of four doses of sCT (1 x 10(-9), 1 x 10(-8), 1 x 10(-7) and 1 x 10(-6) M). sCT did not affect the initial strip basal tone. ACh, CCK-OP and KCl caused, as expected, a powerful contraction of the strips, but no effect was shown when each of the sCT doses was administered before ACh (1.28+ 0.69 SEM without sCT vs 1.28g+ 0.69 with sCT; n = 6) and CCK-OP (1.46g+ 0.19 without sCT vs 1.46g+ 0.19 with sCT; n = 8) or 5 min after the induced KCl contraction. On the basis of these preliminary results, we conclude that no evidence of a direct sCT effect was found on guinea pig GBs when considering either basal smooth muscle tone or isometric contraction in response to ACh, KCl and CCK-OP. Further studies are therefore required to clarify the influence of CT on GB dynamics in vivo and to elucidate its the physiological significance.
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PMID:[In vitro effect of calcitonin on guinea pig gallbladder]. 262 46

Katacalcin is a recently discovered peptide, contained within the calcitonin precursor. For the highly sensitive radioimmunological measurement of katacalcin and calcitonin we used extraction on C-18, thereby lowering the detection limits in serum to 0.8 pmol/l (katacalcin) and 0.7 pmol/l (calcitonin), and simultaneously improving the specificities of both assays for the monomeric forms of the peptides. Extraction recoveries were greater than 96% and greater than 95% for pure monoiodinated [125I]Tyr(0)-katacalcin and [125I]calcitonin, respectively; and 95-98% and 91-97% respectively for the corresponding unlabelled peptides. This method is sufficiently sensitive and specific for studies on the physiology of both peptides. Gel filtration of serum from a patient with medullary carcinoma of the thyroid showed that the majority of high molecular weight forms of katacalcin and calcitonin did not bind to C-18, and that the eluted material consisted to more than 90% of monomeric katacalcin and calcitonin. Basal levels (mean +/- SEM) of katacalcin were higher in men (3.0 +/- 0.6 pmol/l, age less than 40 years, and 1.8 +/- 0.4 pmol/l, age greater than 40 years) and younger women (2.1 +/- 0.4 pmol/l) than in older women (1.3 +/- 0.6 pmol/l; p less than 0.02). The respective values for calcitonin were 5.1 +/- 0.9 and 4.0 +/- 0.6 pmol/l for young and older men, and 2.3 +/- 0.4 and 2.8 +/- 0.8 pmol/l for young and older women, with a significant sex-related difference in both age groups. Basal serum levels of katacalcin and calcitonin were highly correlated (katacalcin = 0.66 calcitonin -0.12 pmol/l; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Determination of circulating monomeric katacalcin and calcitonin: physiological studies in normal subjects. 375 63

Calcitonin-like peptides have been identified in the serum of normal subjects and of medullary thyroid carcinoma (MTC) patients. Using specific homologous radioimmunoassays (RIA) in combination with reversed-phase high performance liquid chromatography and gel permeation chromatography under denaturing conditions, we have recognized major components which coeluted with human calcitonin-(1-32), PDN-21, a carboxyl-terminal flanking peptide derived from the calcitonin mRNA sequence, and salmon calcitonin-(1-32). An additional 12000 molecular weight peak possibly represents a human calcitonin-PDN-21 polyprotein. In both the human calcitonin-(1-32) (normal value less than 0.043 ngEq/ml; MTC 140 +/- 80 ngEq/ml, mean value +/- SEM) and the PDN-21 (normal value less than 0.050 ngEq/ml; MTC 33.6 +/- 16.5 ngEq/ml) RIAs, serum levels were increased in MTC patients. Circulating levels of the salmon calcitonin-like peptide were indistinguishable between normal subjects (0.038 +/- 0.006 ngEq/ml) and MTC patients (0.037 +/- 0.011 ngEq/ml).
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PMID:Salmon and human calcitonin-like peptides in man. 672 77

Abstract Calcitonin gene-related peptide (CGRP) is one of the most potent endogenous vasodilator peptides known so far. Almost all clinical studies using or measuring CGRP are conducted during the day, and hence this study was carried out to see any variations of CGRP levels in the circulation during this period. Three separate studies were conducted. In the first study, following an overnight fast, sequential samples of blood were taken from six healthy volunteers between 0900 and 2100 h and were assayed for CGRP using a highly sensitive and specific radioreceptor assay. A diurnal variation of CGRP in the circulation (P<0.0001) was demonstrated. No difference in the diurnal pattern of CGRP in plasma was seen between males and females. The range of plasma receptor-active CGRP was 2.8 to 13.0 pmol/l (mean +/-SEM, 7.03+/-0.28 pmol/l). Two peaks of CGRP were observed in the circulation (increases of approximately 100% from the basal levels obtained at 0900 h), one around midday (P<0.0001) and the other in the late afternoon (P< 0.005). To assess the contribution of CGRP released from the gut following food, a second study was carried out in which the protocol of the first study was repeated in three volunteers but avoiding any food during the day. Although a similar diurnal variation of receptor-recognized CGRP was seen in this study (P<0.01), the changes observed were significantly lower than those observed in the first study, suggesting that the effect of a meal exaggerates the response of diurnal variation of plasma CGRP. In a third study, circadian variation of receptor-recognized CGRP was examined in three volunteers over a 24 h period. In addition to the diurnal pattern seen with the first study, the plasma CGRP levels continued to decrease up to early morning. The lowest levels of CGRP were detected between 0300 and 0600 h. After this time the levels gradually rose towards midday. It is well accepted that the incidence of cardiovascular episodes is high during the early hours of the morning. Separate studies are necessary to determine if these low levels of 'biologically-active CGRP' in the early hours of the morning are a coincidence, or whether they play a role (e.g. relative deficiency of CGRP) in contributing to the occlusion of already diseased arteries. Furthermore, the diurnal variations of monomeric CGRP demonstrated here imply that, with any experiments relying on the measurement or infusion of CGRP, timing of blood sampling and relationship to meals are important and should be strictly adhered to in most physiological studies with CGRP. This is the first study which demonstrates the circadian variation in plasma concentrations of CGRP.
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PMID:Circadian variation of plasma calcitonin gene-related Peptide in man. 1921 70