Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Parathyroid hormone (PTH) is strongly concerned with the pathogenesis of urinary stones. PTH is mainly regulated by the serum calcium concentration and not by other hormones, as is usually the case. We studied whether PTH is also regulated by adrenocorticotrophic hormone (ACTH) or not. ACTH (0.25 mg) was injected intravenously to 17 patients with primary hyperparathyroidism PHP, 7 patients with urolithiasis, 7 patients with malignant hypercalcemia, and 6 control subjects. Serum calcium was significantly increased in only PHP. The serum calcium increase rate showed a significant positive correlation with serum alkaline phosphatase, and a negative correlation with the preinjected serum calcium. PTH was slightly increased in all four groups. Serum cortisol and ACTH concentrations were not significantly different among the groups. PTH concentration in a culture medium of parathyroid tissues increased after ACTH addition. Serum calcium was significantly increased after ACTH injection in an adrenalectomized rat, and decreased in a parathyroidectomized rat. From our data and those of others, it appears that ACTH acts on the adrenal glands to decrease the serum calcium concentration, and might act directly on the parathyroid gland or bones to increase it.
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PMID:[Studies on the endocrinological metabolism of the parathyroid. II. Influence of ACTH on parathyroid function and calcium metabolism]. 300 38

Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E2 there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.
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PMID:Hormone-responsive cells derived from human dental papilla: characterization in vitro and in vivo in diffusion chambers. 302 24

Bone mass and related metabolic variables were studied in 50 males known to be, or to have been, regular alcohol abusers. Subjects were divided into those who were still drinking and those who had abstained for at least 3 months, and the former further subdivided into moderate and heavy drinkers. Twenty-five had at least two atraumatic spinal crush fractures. In 25 cases, bone histomorphometry was carried out. Lumbar bone mineral density and iliac crest bone volume were significantly lower in spinal crush fracture cases. Parathyroid hormone, testosterone, and urinary cortisol measurements showed no difference between groups. Alkaline phosphatase and 24-hour urine hydroxyproline were higher in osteoporotics than in nonosteoporotics. On bone histomorphometry, there were essentially no differences between those with and those without fractures in terms of bone formation and resorption parameters. Drinkers showed lower osteoid seam width and fraction of osteoid covered by osteoblasts, as well as fewer osteoblasts per 10 cm of bone surface than abstainers. Mineralization lag time was prolonged, and mineralization rate per day was lower in the drinkers. Osteon formation time was prolonged in the drinkers. On the resorption side, only the osteon resorption time was significantly different in the drinkers, being prolonged. The heavy drinkers, but not the moderate drinkers, had a significantly reduced surface extent of lacunae. We conclude that alcohol consumption has clear detrimental effects on bone formation with less pronounced suppressive effects on bone resorption. In no biochemical or hormonal measurement, however, with the exception of hydroxyproline excretion and plasma alkaline phosphatase, could those who had osteoporosis be distinguished from those who did not.
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PMID:Bone histomorphometry, bone mass, and related parameters in alcoholic males. 314 91

Eight patients with childhood acute lymphoblastic leukemia (ALL) and hypercalcemia, osteopenia, or vertebral compression fractures seen at our institution during the last 12 years were evaluated for biochemical evidence of bone disease. Five patients were hypercalcemic, three had abnormal phosphorous levels, and four had elevated alkaline phosphatase values. Parathyroid hormone (PTH) was measured by a polyvalent radioimmunoassay in five patients and these levels were abnormally high in three patients. Four of these five patients also had PTH measured by a midregion-specific radioimmunoassay. One patient had a high PTH value. Two patients had low levels and one patient had a normal PTH level. Although these studies suggest diverse biochemical mechanisms may be contributing to the bone changes and hypercalcemia seen in childhood ALL, ectopic PTH production as well as ectopically produced fragments of PTH may have a role in mediating bone resorption and hypercalcemia.
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PMID:The spectrum of metabolic bone disease in lymphoblastic leukemia. 346 23

We studied mineral metabolism in 15 thyrotoxic patients and 15 controls matched for sex, age, and weight. Thyrotoxic subjects showed significantly higher serum calcium, phosphate, alkaline phosphatase, and globulin and lower serum creatinine, magnesium, and albumin. Parathyroid hormone immunoreactivity (iPTH) was measured with three different antisera. Thyrotoxic patients showed markedly reduced iPTH values in the most sensitive assay, a midregion-specific assay based on homologous antiserum BG-6. Antiserum 211/32 gave slightly reduced iPTH values, but antiserum NG-1 gave values that were increased by 65%. The limited sensitivity of these later two antisera, like that of others used earlier for such studies, may have blunted the apparent fall in iPTH (antiserum 211/32) or predisposed the assay to a systematic artifact (antiserum NG-1). These results show that for use in the evaluation of hypercalcemia in thyrotoxic patients, a PTH assay must first be characterized as to the expected result in uncomplicated thyrotoxicosis. Twelve of the thyrotoxic subjects entered a random order cross-over study in which propranolol and placebo were given in double-masked fashion for 6 consecutive days each. Overall, the drug did not alter calcium, phosphate, or magnesium metabolism. It lowered serum calcium only in two overtly hypercalcemic subjects, whose urinary calcium excretion did not decline. These results confirm that propranolol may reduce elevated serum calcium levels in thyrotoxicosis and suggest that in this setting the drug may have a direct or indirect effect on renal calcium metabolism.
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PMID:A controlled study of the effects of thyrotoxicosis and propranolol treatment on mineral metabolism and parathyroid hormone immunoreactivity. 384 May 65

Fourteen very low birthweight infants (mean +/- SD 1,070 +/- 180 g and 29.3 +/- 1.9 weeks gestation) fed their own mother's milk were clinically followed until 3-4 months of age with frequent measurements of serum calcium, phosphorus, magnesium, 25-hydroxyvitamin D (25-OHD), parathyroid hormone, alkaline phosphatase, and albumin, and urine calcium, phosphorus, and magnesium. These infants were matched for birthweight and gestation with 14 infants (1,075 +/- 152 g and 29.0 +/- 1.7 weeks) who had been similarly followed during concomitant studies of infants fed standard formula (Similac 20 cal/oz). Urine phosphorus was markedly lower in the breast milk-fed group from initiation of feedings, and serum phosphorus became significantly lower at and after 6 weeks of age. The fall in serum phosphorus was accompanied by a marked calciuria. Parathyroid hormone was suppressed in the breast milk-fed group, although serum calcium was not elevated and did not differ from formula-fed infants. A high incidence of moderate-severe hypomineralization on radiographs was seen in both breast milk- and formula-fed groups. Six of 14 breast-fed infants required phosphorus supplementation at 8-10 weeks of age because of significant hypophosphatemia, hypercalciuria, and hypomineralization. These infants differed from those not requiring phosphorus supplements by being smaller at birth but not of lower gestation, and having persistently low serum 25-OHD at and after 6 weeks of age.
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PMID:Serial serum 25-hydroxyvitamin D and mineral homeostasis in very premature infants fed preterm human milk. 387 19

Osteoblasts and osteocytes in adult thyroparathyroidectomized (T(x)PT(x)) rats fed a low calcium vitamin D-free diet and given parathyroid (PTH) had ultrastructural evidence of increased activity compared to controls. Osteoblasts in PTH-treated rats had prominent rough endoplasmic reticulum and Golgi apparatuses and large mitochondria. The plasma membranes were extensively convoluted and associated with initial loci of mineralization in osteoid. Osteocytes contained increased rough endoplasmic reticulum, well-developed Golgi apparatuses and large mitochondria. Lacunar walls were roughened, but osteocytic osteolysis was not observed. Osteoclasts were encountered more frequently in PTH-treated rats, but their ultrastructural features were similar to those of controls. Osteoblasts and osteocytes in controls appeared to be inactive cells lining quiescent mineral surfaces. Parathyroid hormone treatment increased serum calcium levels and urinary hydroxyproline excretion, indicating enhanced resorption of bone mineral and matrix. Bone alkaline phosphatase and calcium-adenosine triphosphatase activities were elevated after PTH treatment and may be related to increased calcium transport by bone cells. These findings were interpreted to suggest that PTH mobilizes bone mineral by osteoclasis and increases metabolic activity of the osteocyte-osteoblast pump.
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PMID:Effects of parathyroid hormone on bone of thyroparathyroidectomized rats: an ultrastructural and enzymatic study. 427 12

Collagenase digestion of young rat condyles released cells which were grown in culture during two weeks. Morphologically, two populations of cells were distinguished, one of which reacted to alkaline phosphatase and resembled chondroblast or osteoblast-like cells. Parathyroid hormone stimulated a 2-fold increase in cellular cyclic AMP, whereas calcitonin had no effect. Physical forces activated cellular cyclic AMP to a 2.5-fold of control levels and increased the incorporation of radioactive thymidine into DNA by 50 per cent. In contrast to cultured bone cells, the response to physical forces was not inhibited by indomethacin in cultured condyle cells. It seems, therefore, that condyle cells are specific in their response to bone-seeking hormones and physical forces.
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PMID:Mechanical and hormonal stimulation of cell cultures derived from young rat mandible condyle. 609 51

Indices of vitamin D metabolism were studied before and after infusion of bovine parathyroid hormone extract in three children with osteopetrosis. Basal serum concentrations of calcium, alkaline phosphatase, and 25-hydroxyvitamin D tended to be low. Serum immunoreactive parathyroid hormone levels were in the upper normal range in two patients. A marked increase in urinary cyclic adenosine 3':5'-monophosphate (cAMP) in all patients was solely due to an increase in the nephrogenous cAMP. The basal concentration of 1,25-dihydroxyvitamin D was clearly more than the upper limit of normal range in all three patients and increased after parathyroid extract infusion in one patient. The basal serum levels of 24,25-dihydroxyvitamin D were within normal limits and tended to decrease after parathyroid extract infusion in two of the patients. Parathyroid hormone and 1,25-dihydroxyvitamin D act in concert to increase calcium resorption from bone, and the increased serum levels of both these factors may reflect lack, or unresponsiveness, of target cells in bone.
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PMID:Effect of parathyroid hormone on vitamin D metabolism in osteopetrosis. 626 77

To show adenylate cyclase (AC) activity in rat calvaria, it is necessary first to decalcify the specimen. In hard tissues, several enzymes (adenosine triphosphatase (ATPase), alkaline phosphatase (APase), adenylate cyclase (AC) and perhaps pyrophosphatase (PPiase) are able to degrade adenosine triphosphate (ATP). The presence of sodium fluoride (NaF) in the incubation medium reduces the quantity of precipitate formed, compared to that observed using a NaF-free incubation medium. Levamisole, used under the same conditions, gives similar results. Possibly NaF inhibits pyrophosphohydrolase and/or phosphatases which mask the AC activity. Adenylylimidophosphate (AMP-PNP), which is a specific AC substrate, confirms the results obtained with ATP. AC activity is demonstrated cytochemically in the osteoblast and preosteoblast membranes, at the junction between two osteoblasts and along the cytoplasmic processes of the osteoblast which penetrate into the osteoid matrix. The osteocytes never show a precipitate, except those which present some osteoblastic features and then only on the membrane facing the osteogenic layer. An intracellular reaction is also evident and is discussed. Parathyroid hormone (PTH) does not reveal new sites of AC activity but increases the quantity of precipitate observed.
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PMID:An attempt at localizing adenylate cyclase in rat calvaria. Influence of sodium fluoride and parathyroid hormone. 700 93


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