UMLS:C0011570 - FACTA Search

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Query: UMLS:C0011570 (depression)
172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Short term in vitro experiments showed that, added alone, verapamil inhibited both glycolysis and Ca uptake in embryonic chicken and rat bone cells. Added together with PTH, verapamil (0.02 MM) enhanced cAMP production, had no effect on lactate production, but significantly inhibited citrate, calcium and phosphate release from embryonic rat and mouse calvaria incubated under hypocalcemic conditions. The depression by verapamil of PTH-stimulated demineralization was confirmed histologically. It is concluded that in addition to cAMP, Ca plays a key role in the action of PTH on bone.
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PMID:The effect of verapamil on the action of parathyroid hormone on embryonic bone in vitro. 20 Apr 41

In early chronic renal failure, the state of the bones resembles that of type II primary hyperparathyroidism. Cortical bone becomes thinner and more porous, and there is increased extent of surface remodeling. These changes are followed in turn by osteomalacia and osteitis fibrosa, although sometimes these may be alternate rather than successive stages. Bone turnover is less than would be expected for the elevation of PTH level, probably because of 1,25 (OH)2D3 deficiency. The resorption velocity and lamellar bone appositional rates are depressed, but woven bone appositional rate may be increased, possibly because of hyperphosphatemia. Bone mass reflects the summation of three independent processes: loss of lamellar bone due to hyperparathyroidism (depending on the extent of insulation by osteoid); accumulation of partly mineralized osteoid because of osteomalacia; accumulation of woven bone because of osteitis fibrosa. Osteosclerosis may be growth-related metaphyseal, subchondral or diffuse axial, and periosteal neostosis may also occur. Some patients on hemodialysis lose bone because of planing rather than lacunar or dissecting resorption, combined with depression of both lamellar and woven bone formation. Hyperparathyroid bone disease tends to improve slowly after renal transplantation. Persistent hypocalcemia reflects a defect in the calcium homeostatic system and cannot be explained solely by the known stimuli to secondary hyperparathyroidism. The increment in plasma calcium in response to PTH infusion is subnormal, both in early chronic and in acute renal failure, probably because of 1,25(OH)2D3 deficiency. This is also the most likely explanation for the depressed level of blood-bone equilibrium. The activity of all three of the PTH responsive cell systems in bone is depressed in renal failure, probably because all three require 1,25(OH)2D3 in order to function normally. In pseudohypoparathyroidism, as in chronic renal failure, hypocalcemia results from a defect in the regulation of the blood-bone equilibrium. The bone-remodeling system shows all gradations of response, from slight depression of bone turnover to overt osteitis fibrosa, but bone turnover is never as low as in PTH deficiency. These differences may reflect the presence or absence of resistance to PTH of the osteoprogenitor cell as well as of the calcium homeostatic system, or may be due to varying degrees of 1,25(OH)2D3 deficiency, as in chronic renal failure. An increase in plasma calcium in response to PTH can occur either in the untreated state or after treatment with vitamin D because either the error-correcting or remodeling system remains responsive to PTH. Pseudohypoparathyroidism may be subdivided into three types, depending on whether the urinary cyclic-AMP response to PTH remains defective despite treatment with vitamin D, improves with treatment, or is normal before treatment. Only the former is associated with the genetic syndrome of Albright's hereditary osteodystrophy...
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PMID:The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone disease. Part IV of IV parts: The state of the bones in uremic hyperaparathyroidism--the mechanisms of skeletal resistance to PTH in renal failure and pseudohypoparathyroidism and the role of PTH in osteoporosis, osteopetrosis, and osteofluorosis. 78 23

The mechanisms of hypercalcemia were assessed in 15 patients with humoral hypercalcemia of malignancy (HHM) who had tumors at various stages of progression. In patients with early tumors, bone biopsies were generally normal and the hypercalcemia was due to an elevation in renal tubular resorption of calcium. Conversely, osteoclastic resorption was markedly increased in patients with advanced tumors, particularly those in whom the biopsies were obtained postmortem. Osteoclast surface (Oc.S) correlated positively with the stage of tumor progression (r = 0.80, p less than 0.002), degree of immobility (r = 0.87, p less than 0.002), and level of urinary cyclic AMP excretion (r = 0.60, p less than 0.02). When compared with a group of ambulant patients with primary hyperparathyroidism (HPT), osteoblast surface (Ob.S%) in HHM was depressed (median and range): 1.2% (0-11.6%) versus 5.3% (1.1-32.0%) (p less than 0.001). However, a relatively low Ob.S (4%) and raised Oc.S (43.5%) were also seen in an immobilized patient with severe HPT. These data suggest that the PTH-related peptides currently invoked in the pathogenesis of HHM may initially cause hypercalcemia by enhancing renal tubular calcium resorption. The increase in osteoclastic activity and depression of osteoblastic activity that subsequently occurs is probably due to the combined effects of immobilization and higher circulating levels of PTHrP on the skeleton. However, the release of other bone-resorbing factors by the tumor, which have a depressant effect on osteoblastic activity, remains possible.
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PMID:Contrasting mechanisms of hypercalcemia in patients with early and advanced humoral hypercalcemia of malignancy. 271 73

Serum calcitriol and the free calcitriol index together with factors considered to regulate calcitriol production were measured in eleven patients with moderate chronic renal failure (MCRF) and eleven age- and sex-matched normal subjects. Although the serum dialysable calcium levels were similar in the two groups, there was depression of calcitriol levels and an elevation of PTH and nephrogenous cyclic AMP (NcAMP) levels in the MCRF patients. Furthermore, plasma phosphate levels were higher and the renal phosphate threshold was depressed in this patient group. When all subjects were grouped together calcitriol was positively correlated with GFR. When calcitriol levels were factored for GFR, to permit an assessment of calcitriol production per unit functioning renal mass, there was no significant difference between normal and MCRF subjects. To determine whether reserve for calcitriol production existed, six of the MCRF patients and six of the age- and sex-matched normal subjects received a low calcium diet for one week supplemented by cellulose phosphate to bind calcium within the gut. In both groups there was a significant rise in calcitriol, although the absolute levels were much lower in the MCRF patients than the normal subjects. These results suggest that calcitriol deficiency is a major feature of MCRF despite marked hyperparathyroidism. The rise in calcitriol levels in MCRF suggests persistent reserve secretory capacity in this condition. Therefore, the low serum calcitriol concentration may be due not only to structural renal damage, but also to suppression of calcitriol formation perhaps due to altered renal phosphate handling.
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PMID:Calcitriol deficiency with retained synthetic reserve in chronic renal failure. 283 40

Urinary cyclic AMP (cAMP) and phosphate were measured before and after calcium infusion in 12 patients with operatively verified primary hyperparathyroidism (PHP) and in 12 healthy persons. In normal subjects infusion of calcium caused a reduction in urinary cAMP directly correlated to the preinfusion values and inversely correlated to the serum calcium concentration determined as albumin-corrected serum calcium. In normal subjects with high normal albumin-corrected serum calcium the infusion of calcium caused no or only a small depression in the urinary excretion of cAMP. Changes in phosphate excretion were not correlated to the calcium concentration. Four of the 12 hyperparathyroid patients showed normal relative suppression in urinary cAMP after the infusion of calcium, and 5 had normal suppression of phosphate excretion. It is concluded that some patients with PHP retain calcium-sensitive secretion of PTH, and that the classical calcium infusion test is of doubtful value in the diagnosis of PHP.
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PMID:Influence of calcium infusion on urinary cyclic AMP and phosphate in hyperparathyroidism. 627 Sep 86

In the presence of b.PTH (1.2 I.U./ml) in the incubation medium, the Na efflux rate constant (degree KNa) of isolated rat enterocytes was significantly reduced when compared to control experiments. The mean depression of degree KNa induced by b.PTH was 26% as compared to control (100%). No depressant effect of b.PTH on degree KNa was observed when the isolated enterocytes were incubated with ouabain (4.0mM). Thus, b.PTH appeared to inhibit the ouabain-sensitive Na pump. When incubating the isolated epithelial cells in an EGTA-containing Ca free medium, b.PTH lost its capacity to inhibit degree KNa. Thus, the presence of extracellular Ca appeared necessary for the inhibitory effect of b.PTH. In contrast to its effect on degree KNa, b.PTH induced no change of net Na uptake by isolated enterocytes. Moreover, b.PTH did not induce significant changes in enterocyte cAMP or cGMP concentrations. It was concluded that b.PTH exerted a direct inhibitory effect on the ouabain-sensitive Na efflux rate constant of isolated rat enterocytes. The effect of b.PTH occurred without a measureable activation of the cyclic nucleotide system but needed the presence of Ca in the incubation medium to be operative.
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PMID:Effect of parathyroid hormone on rat enterocyte Na transport in vitro. 718 Jun 68

1. The sympathetic superior cervical ganglia (SCG) provide innervation to the pineal gland and median eminence through the internal carotid nerve and to the thyroid and parathyroid glands through the external carotid nerve. 2. Postsynaptic activation in median eminence nerve endings shortly after superior cervical ganglionectomy (SCGx) was accompanied by a depression of LH and FSH release and by a 3-5 day delay in rat estrous cyclicity. A decrease in TSH and GH release and an increase in ACTH and prolactin release were also found. These effects were accompanied by a) an increase in medial basal hypothalamic (MBH) LHRH, TRH and GHRH, b) a decrease in MBH somatostatin, AVP and CRH, and c) a normal adenohypophyseal response to hypophysiotropic hormones. Neurohypophyseal AVP release decreased during degeneration of sympathetic nerve terminals in the neurohypophyseal lobe after SCGx. The effects were generally mediated by alpha 1-adrenoceptors and were pineal gland. 3. In thyroid and parathyroid tissue the following events were observed during the wallerian degeneration phase after SCGx: a) alpha 1-adrenoceptor inhibition of thyroxine (T4) release, b) alpha 1-adrenoceptor inhibition, together with beta-adrenoceptor stimulation, of calcitonin release, and c) alpha 1-adrenoceptor inhibition of parathyroid hormone release. Thyroid sympathetic nerves also modulate slow phenomena such as compensatory thyroid growth after partial thyroidectomy. 4. In rats subjected to cholinergic decentralization of the thyroid gland, a decrease of plasma T4 and an increase of plasma TSH, as well as an impaired goitrogenic and thyroid compensatory response were detectable. The calcitonin and PTH response to changes in calcium levels increased after regional parasympathetic denervation. 5. The results indicate that cervical autonomic nerves constitute a parallel pathway through which the brain communicates with the endocrine system.
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PMID:Peripheral neuroendocrinology of the cervical autonomic nervous system. 808 Dec 83

A 56-year-old white man was referred for evaluation of severe hypercalcemia following a three-week history of progressive weakness, nausea, and depression. Initial laboratory results showed serum total and ionized calcium (Ca++) values of 5.3 and 2.6 mmol/l, respectively. A short intact PTH assay was immediately performed and an extremely high value was obtained in just 30 min (1315 ng/l, normal values 6.4-70.4). The patient was therefore treated with saline solution and with salmon calcitonin (1200 IU/day, half by continuous i.v. infusion and half by i.m. route) for 10 days. There was a sudden decrease of both Ca++ and intact PTH during the first six days; then there was a trend to reach a steady-state until parathyroidectomy was performed. After withdrawal of calcitonin therapy it was possible to observe a positive uncoupling between bone formation (serum alkaline phosphatase and osteocalcin) and resorption (serum tartrate-resistant acid phosphatase) markers. On day 35 the patient underwent neck exploration, and an enlarged lower left parathyroid gland was removed that on macroscopic examination revealed the presence of a haemorrhagic cyst; microscopic appearance was suggestive of a previous glandular infarction. This is the first time the daily clinical course of a parathyroid crisis has been documented. Furthermore, changes of biomarkers of bone turnover following calcitonin therapy show that high doses of the hormone may cause a prolonged positive uncoupling of the two processes of bone remodeling.
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PMID:Parathyroid storm: immediate recognition and pathophysiological considerations. 826 42

Many studies document bone loss at diagnosis in patients with PHPT (including mild PHPT) that is greater than would be expected in comparable persons without this condition. However, there is no general agreement regarding the severity of bone mass loss in these patients and the rate at which it progresses. A few studies suggest that such accelerated osteoporosis may be self-limited, with patients showing no further decline in BMD after diagnosis. There is insufficient evidence to conclude that PTH-related bone loss is associated with an increased risk of fracture. The few studies that have evaluated the risk of fracture in these patients are conflicting. Some evidence also suggest that, like bone loss in these patients, fracture risk may change during the course of the disease. One study found that patients with PHPT (including those with mild hypercalcemia) were more likely than matched controls to have a history of fractures prior to diagnosis, but that both groups had similar rates of fractures during followup. Moreover, the studies of fractures suffer from several limitations, such as nonrandomization of patients, different definitions of vertebral fractures, small study populations, and short followup times. There is also insufficient evidence to determine the effect of parathyroidectomy on the incidence of fractures in patients with mild PHPT, partly because the natural history of this condition is incompletely understood. Although studies demonstrate that patients with PHPT gain bone mass following parathyroidectomy, the bone reparation is incomplete and bone mass density remains below normal, even though the hyperparathyroidism is cured. Currently, decisions to perform parathyroidectomy are based on signs and symptoms of bone disease, metabolically active renal stones, decreased renal function, fatigue and/or depression, and high levels of serum calcium. Although the use of bone mass measurements has been advocated to aid clinical decisions regarding the risks and benefits of surgery, specific bone changes that indicate the need for parathyroidectomy have not been clearly established. There are virtually no prospective data that evaluate decisions to operate based upon bone mass measurements nor randomized clinical trials comparing the outcome of surgically treated patients with those who have not had surgery. Based on the literature, bone mass measurements cannot predict who among asymptomatic patients will require parathyroidectomy. There is some evidence that nonsurgically treated patients and those who remained hypercalcemic after unsuccessful surgery lost bone at the same percentage rate as normal control subjects.
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PMID:Bone densitometry: patients with asymptomatic primary hyperparathyroidism part I. Technical report. 893 32

The motility of the reticulo-rumen has been measured in trained, conscious sheep using inflated balloons temporarily introduced to selected regions of that forestomach. The frequency and amplitude of the contractions of the reticulum and both the A and B waves of contraction of the rumen were measured under the same conditions before, during and after the administration of an i.v. bolus of either parathyroid hormone (PTH(1-34)) or PTH-related protein (PTHrP(1-34)) followed by its i.v. infusion. These two peptides are known to share a common receptor in other organs, e.g. the kidney. In this study they both showed an inhibitory effect on reticulo-ruminal motility. The effect of PTHrP(1-34) on the rate of ruminal blood flow was also examined and a significant reduction observed, after a transient increase. The secretion of endogenous PTH(1-34) was stimulated by a 32% reduction in the plasma calcium ion concentration induced by an i.v. infusion of sodium citrate. Associated with this were significant reductions in reticulo-ruminal motility, e.g. the reduction in the mean amplitude of the reticular contractions reflected the reduction in plasma calcium ion concentration. When the PTH(1-34)/PTHrP(1-34) receptor was blocked with [Asn10,Leu11,D-Trp12]PTHrP(7-34) before and during the induction of hypocalcaemia, all but one of the parameters of reticulo-ruminal motility were normalized. Indeed, by the day following the administration of this blocking agent, all these parameters had returned to their normal range. It is concluded that stimulation of the PTH(1-34)/PTHrP(1-34) receptor in reticulo-ruminal smooth muscle reduces the motility of this tissue and may play a role in the depression of motility of the digestive tract which is characteristic of clinical milk fever in the dairy cow.
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PMID:The relaxant effects of parathyroid hormone(1-34) and parathyroid hormone-related protein(1-34) on ovine reticulo-ruminal smooth muscle in vivo. 1048 Dec 24

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