Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific binding studies of tritium-labeled LH-RH to sheep anterior pituitary membranes at 37 degrees C showed a maximum of binding capacity of 110 +/- 20 mol/mg protein with an association rate constant of 2 +/- 1 X 10(5) M-1 S-1 and a dissociation rate constant of 0.7 +/- 0.4 X 10(-2) S-1. The Scatchard plot data showed a single type of binding site with Kass = 1.1 +/- 0.4 X 10(8) M-1 in good agreement with the kinetic studies. Various doses of LH-RH in the presence or absence of Ca2+, were unable to stimulate adenylate cyclase either in the rat anterior pituitary homogenates, or in the purified sheep anterior pituitary plasma membranes. To explain these results, it may be argued that the proportion of gonadotrophs in the pituitary gland is too small to show a significant increase in the LH-RH-induced adenylate cyclase activity. Another possibility is the disconnection of the hormonal receptor from the site of activation of adenylate cyclase during the preparation of plasma membranes. Finally, cAMP may not be involved in LH release by LH-RH.
Mol Cell Endocrinol 1976 Oct
PMID:Binding of gonadotropin-releasing hormone (LH-RH) to the pituitary plasma membranes and the problem of adenylate cyclase stimulation. 82 66

1. Whewellite (calcium oxalate monohydrate) crystals were found to induce epitaxially the heterogeneous nucleation of brushite (calcium monohydrogen phosphate dihydrate) from its metastable supersaturated solution in approximately one-quarter of the time required for spontaneous precipitation in the absence of added nucleating agents. Scanning electron-microscope observation of the crystalline phase showed brushite crystals originating from the whewellite seed crystals. 2. Crystal growth, upon nucleation, proceeded rapidly, and the metastable solutions quickly approached saturation. 3. Brushite crystals also induced the precipitation of calcium oxalate crystals in about one-quarter of the time required for spontaneous precipitation; however, the rate of crystal growth was considerably slower. In support of the chemical data, scanning electron micrographs showed few crystals of calcium oxalate nucleated on the surface of the brushite seed. 4. The results provide some insight into the cause of stones containing calcium oxalate or calcium phosphate (or both), which form in the normally acid environment of human urine.
Clin Sci Mol Med 1977 Feb
PMID:Epitaxial relationships in urolithiasis: the brushite-whewellite system. 84 47

1. Five patients with the osteomalacia of chronic renal failure were given 50--100 nmol of 25-hydroxy vitamin D3 intravenously per day for 24--28 days. 2. In all five patients, during administration of 25-hydroxy vitamin D3 there was a substantial rise in the plasma concentration of 25-hydroxy vitamin D from initially abnormally low values. 3. Significant improvement in bone mineralization, intestinal calcium absorption and muscle strength occurred in the three patients with the greatest rise in plasma 25-hydroxy vitamin D.
Clin Sci Mol Med 1977 May
PMID:The effect of 25-hydroxy vitamin D3 in the osteomalacia of chronic renal failure. 86 43

The effects of lanthanum on the activity of purified preparations of acetylcholinesterase (AChE) from the electric organ of E. electricus and on the activity of AChE in intact electroplaques from the same species were studied. 0.1 mM LaCl3 produced an initial inhibition of purified AChE which was followed by a delayed activation of the enzyme. Upon pretreatment of purified enzyme with LaCl3, initial activity was markedly increased. LaCl3 exerted a marked, concentration-dependent inhibition of intact cell AChE. La3+ and Ca2+ appear to interact competitively. In the presence of both 10 mM CaCl2 and 0.1 mM LaCl3, the initial activitity of purified AChE was increased at lower ACh concentrations and inhibited at ACh concentrations greater than 3 X 10(-4) M. Inhibition of intact cell enzyme by 0.1 mM LaCl3 was relieved by increasing the CaCl2 concentration to 10 mM at ACh concentrations less than 2 X 10(-4) M. The data were analyzed assuming Michaelis-Menten kinetics and interpreted with reference to the differential binding of divalent and trivalent cations to regulatory anionic sites which are separate and distinct from the anionic site of the active center of the enzyme.
Mol Cell Biochem 1977 May 31
PMID:Interactions of lanthanum with purified and intact cell acetylcholinesterase of Electrophorus electricus. 88 82

Human urinary Tamm-Horsfall glycoprotein, which contains 28% carbohydrate, has a monomeric molecular weight of about 80,000 but is isolated from urine in the form of intertwining helical suprastructures with molecular weights greater than 10(7). The native glycoprotein was dissociated and denatured with 6 M guanidinium chloride and was subsequently renatured by dialysis against a Tris-HCl buffer. Using sedimetation equilibrium, the renatured glycoprotein was characterized by a Mw cell of 256,800 and a Mz cell of 356,000. The ratio, Mz/Mw, of 1.39 indicates some polydispersity with regard to molecular size. There was no evidence of helical suprastructures in the renatured glycoprotein as judged by electron microscopy. Ca2+ concentrations of up to 50 mM failed to precipitate the renatured glycoprotein; in contrast, the native glycoprotein is precipitated by Ca2+ concentrations between 5-10 mM. The circular dichroic spectrum of renatured Tamm-Horsfall glycoprotein was obtained, resolved, and tentative band assignments made. The spectrum, which is quite similar to that of native Tamm-Horsfall glycoprotein, exhibited negative extrema at 269 nm (due in large part to disulfides and tyrosines) and at 215 nm (due to protein beta-structure and the N-acetylated hexosamines). The alpha-helical content of the glycoprotein was estimated to be no more than 10% and the amount of beta-structure to be about 33%; these values were not affected by the presence of Ca2+ (1 mM). A glcopeptide fraction (ca. 90% carbohydrate), prepared by extensive pronase digestion of the reduced, S-carboxymethylated glycoprotein, exhibited an ellipticity extremum at 212 nm of + 4,750 deg-cm2/dmole, referred to the concentration of (N-acetylated) hexosamines and neuraminic acid.
Mol Cell Biochem 1977 Apr 12
PMID:Circular dichroism of human urinary Tamm-Horsfall glycoprotein. 89 29

1. Chemical and morphological features of uraemic bone disease were studied by comparison of bone composition in 44 patients with uraemia (12 dialysed and 32 non-dialysed) and 36 control subjects. The significant changes included decreased bone mineral carbonate associated with calcium, a concomitant increase in phosphate, and an increase in magnesium. There was also an increase in osteoid and a reduction in the specific gravity of the compact bone. 2. The most marked changes in bone composition were observed in patients with uraemia of more than 1 year's duration, who had been dialysed. Bone mineral sodium concentrations were not significantly altered in any group. 3. The changes in bone mineral composition appeared to be the result of several simultaneous and/or successive mechanisms: (i) loss of fixed base, calcium carbonate; (ii) replacement of carbonate by phosphate; (iii) the addition of immature bone mineral, which contains high concentrations of phosphate and relatively low concentrations of carbonate. 4. These observations are consistent with earlier views of the bone salt as an indefinite calcium/phosphate/carbonate complex. Variations in bone composition may arise from a reciprocal relationship between phosphate and carbonate. The bone mineral analogue that best explains these variations in bone composition is octacalcium phosphate carbonate [Ca4 (PO4)2(HPO4)x(CO3)1-x,zH2O].
Clin Sci Mol Med 1977 Oct
PMID:Inter-relationships of carbonate, phosphate, monohydrogen phosphate, calcium, magnesium and sodium in uraemic bone: comparison of dialysed and non-dialysed patients. 91 54

1. The effect of purified bovine parathyroid hormone on renal tubular reabsorption of sodium and calcium has been studied by micropuncture in intact and recently thyroparathyroidectomized dogs. 2. Parathyroid hormone increased the rejection of sodium and calcium proportionately at the late proximal tubule in both intact and operated dogs. 3. In both groups of dogs, there was increased delivery of sodium and calcium to the distal tubule after the hormone. However, the Ca/Na ratio decreased, suggesting some selective enhancement of calcium reabsorption before the superficial distal puncture site. 4. In the final urine, the Ca/Na ratio decreased highly significantly in both groups of dogs, indicating a further selective effect of parathyroid hormone on calcium reabsorption in or beyond the distal convoluted tubule.
Clin Sci Mol Med 1976 Oct
PMID:Effects of parathyroid hormone on sodium and calcium transport in the dog nephron. 97 75

1. A method of measuring changes in the total body content of calcium, phosphorus, nitrogen and sodium in rats by activation analysis in vivo is described. 2. The change in the body content of the elements has been measured in rats on a calcium-deficient diet and in control animals, the body nitrogen being used to represent lean body mass for normalization. 3. There were siginificant differences in Ca/N and P/N but not in Ca/P ratios between the animals on a deficient diet and control animals at the end of the dietary period.
Clin Sci Mol Med 1976 Oct
PMID:A study of changes in whole-body calcium, phosphorus, sodium and nitrogen by neutron activation analysis in vivo in rats on a calcium-deficient diet. 97 80

1. Five normal subjects were given 100 ml of aluminium hydroxide gel per day for 28 days. 2. The phosphorus balance became more positive in one subject, less negative in two and changed from negative to positive in the other two subjects. This was accompanied by a rise in the concentration of the fasting morning plasma phosphorus. Calcium balance did not change. 3. The normal subjects absorbed 0-3-3-6 mmol of aluminium/day, which is significantly less than that absorbed by five patients with chronic renal failure, three of whom were studied before, and two after, the observations on the normal subjects had been completed. 4. In a further five normal subjects on 100 ml of aluminium hydroxide gel/day the 08.00 hours concentration of plasma phosphorus did not fall, though there was a fall at 11.00, 14.00 and 17.00 hours.
Clin Sci Mol Med 1976 Oct
PMID:The effect of aluminium hydroxide orally on calcium, phosphorus and aluminium metabolism in normal subjects. 97 81

Determinations of the calcium pools in myocardial cells in vitro have shown the existence of at least three pools of exchangeable calcium. Epinephrine and glucagon were found to produce significant increases in the size of the two slower exchanging pools. Prostaglandins E1 and F1alpha also increased significantly calcium pool size whereas E2 and F2alpha did not; results which correlate well with the effects of the two former prostaglandins on intracellular cAMP levels. The results imply that these agents cause small, but significant, changes in the transmembrane exchange of calcium and large increases in the intracellular calcium pool. Effects which may involve the direct or indirect action of cAMP.
Mol Cell Endocrinol 1976 Oct
PMID:The effects of hormones and prostaglandins on the calcium pools in cultured myocardial cells. 97 90


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