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)

The clinical, biochemical, radiological and scintigraphical data related to renal osteodystrophy were followed in 18 patients on CAPD for 3 to 5 years. The majority maintained normal serum calcium, bicarbonate and alkaline phosphatase concentrations; serum phosphate concentration decreased after starting CAPD but remained somewhat elevated. Only half of the patients needed phosphate binders. Serum PTH concentrations fell in those with high values at the start and remained stable in most others. Serum aluminum concentrations never exceeded 50 micrograms/l while serum 25(OH)D3 levels remained low. Bone radiology and scintigraphy were characterized by their stability over time. We think that CAPD, with the addition of calcium carbonate, phosphate binders and vitamin D analogs can achieve good control of renal osteodystrophy. In addition, joint problems are not common in CAPD patients but we present evidence that they too are at risk of dialysis amyloidosis.
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PMID:[Bone and joint complications in patients treated with continuous ambulatory peritoneal dialysis (CAPD) for more than 3 years]. 281 91

Chronic hypercapnia is associated with increased proximal HCO3 reabsorption that is thought to be mediated by a Na-H antiporter. We hypothesized that chronic hypercapnia would be associated either with increased Vmax or with decreased Km of the Na-H antiporter. To test this hypothesis we made rabbits hypercapnic for 48 h by exposure to 10% CO2. In both control and hypercapnic animals, cortical luminal membranes were enriched over the homogenate 16-fold in alkaline phosphatase and 10-fold in maltase activity. The kinetic activity of the Na-H antiporter was measured by the dissipation of the quenching of acridine orange by addition of different Na concentrations. Chronic hypercapnic rabbits had significantly higher Vmax of the Na-H antiporter of luminal membranes than controls (593 +/- 81 vs. 252 +/- 40 arbitrary fluorescence units X min-1 X 300 micrograms protein-1, P less than 0.01). The Km, however, was not different between control and hypercapnic rabbits. 22Na uptake in presence of an outwardly directed pH gradient was significantly higher in vesicles from hypercapnic rabbits than controls. Amiloride inhibited the Na-H antiporter (as assessed by acridine orange quenching or 22Na uptake) to the same degree in membranes from both control and hypercapnic rabbits, suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. In addition, under voltage clamp conditions by K and valinomycin the Vmax was still increased in membranes from hypercapnic animals, again suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. The uptake of D-[3H]glucose by luminal membranes was not different between control and hypercapnic rabbits, indicating a specific enhancement of the Na-H antiporter. Acute hypercapnia (4 h) failed to increase the Vmax of the Na-H antiporter despite comparable increase in PCO2. Thus chronic hypercapnia, but not acute hypercapnia, induces a selective and specific increase in the Vmax of Na-H antiporter, and this may mediate the adaptation to chronic hypercapnia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Chronic hypercapnia enhances Vmax of Na-H antiporter of renal brush-border membranes. 282 Feb 41

We studied the relationship between urinary and nephrogenous cyclic adenosine monophosphate (CAMP) and intake of calcium in patients with clinical osteoporosis. Serum and urinary Ca, alkaline phosphatase, and CAMP were measured by standard techniques. Lumbar mineral density was assessed by dual photon absorptiometry. Mean (+/- SD) urinary and nephrogenous CAMP was 4.6 +/- 1.4 mumol/g creatinine (0.52 +/- 0.16 mumol/mmol creatinine) and 15 +/- 8.0 nmol/L GF in patients using an extra gram of Ca carbonate daily and 6.5 +/- 2.6 mumol/g creatinine and 32 +/- 18 nmol/L GF in patients consuming dietary Ca (p less than 0.05). Serum Ca was increased (p less than 0.05) in the supplemented group (9.8 +/- 0.4 vs 9.3 +/- 0.6 mg/dL [2.4 +/- 0.099 vs 2.32 +/- 0.14 mmol/L]) but urinary Ca and serum alkaline phosphatase were similar. Bone mineral density was the same in both (0.88 +/- 0.19 vs 0.87 +/- 0.08 g/cm2). We concluded that CAMP is greater in patients with no supplemental Ca in the diet. This test may be useful to assess patient compliance and biological availability of dietary or supplemental Ca.
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PMID:Monitoring calcium intake in osteoporosis by assay of nephrogenous cyclic AMP. 283 77

Fourier transform infrared spectroscopy (FTIR) was used to characterize the organic and mineral phases present during the induction of mineral formation by collagenase-released matrix vesicles (CRMV) during incubation in a synthetic cartilage lymph in vitro. CRMV mineralization, which occurs in the absence of alkaline phosphatase organic phosphate substrates, is characterized by an initial short lag period of limited Ca2+ accumulation, followed by a period of rapid Ca2+ uptake, and finally, by a plateau period during which Ca2+ accumulation continued at a slower rate. FTIR spectra taken at timed intervals during the induction of mineralization revealed the presence of absorptions characteristic of protein, phospholipid, and mineral components in the CRMV. These became progressively more intense with time. To reveal underlying changes occurring during the successive stages of Ca2+ accumulation, FTIR spectra of nascent (or demineralized) CRMV were computer-subtracted from subsequent spectra, nulling on the C-H stretch modes characteristic of the lipid acyl chains. These difference spectra showed little change during early Ca2+ loading, revealing that mineral ions initially accumulated in a form similar to that present in nascent matrix vesicles (MV). During the period of rapid Ca2+ uptake prior to appearance of crystalline mineral, difference spectra revealed subtle changes in the carbonyl and amide nitrogen stretch modes indicative of protein conformational changes. The first definable mineral phase appeared late in the rapid Ca2+ uptake period and was a distinct, crystalline octacalcium phosphate (OCP)-like phase. With time, the OCP-like precursor became more apatitic in character. There was no evidence that any amorphous calcium phosphate phase formed during the MV mineralization sequence. The mature MV mineral phase closely resembled hydroxyapatite formed via an OCP precursor and was similar to other biological apatites that show a substantial incorporation of carbonate.
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PMID:Fourier transform infrared characterization of mineral phases formed during induction of mineralization by collagenase-released matrix vesicles in vitro. 284 33

Present evidence suggests that in the small intestine, villus cells are primarily absorptive and crypt cells are primarily secretory. In order to further confirm that there are differences in transport properties between villus and crypt cells, we have separated villus from crypt cells, using calcium chelations techniques, and determined the distribution of Na:H and Cl:HCO3 exchange activity on brush border membrane and basolateral membrane preparations from these two cell populations. Separation of cells was determined utilizing alkaline phosphatase and maltase activity as a marker of villus cells and thymidine kinase activity as a marker of crypt cells. Utilizing these techniques, we were able to sequentially collect cells along the villus-crypt axis. Na-stimulated glucose and alanine uptake in brush border membrane vesicles diminished from the villus to the crypt region in the sequentially collected cells fractions, further suggesting separation of these cells. Brush border and basolateral membranes were then prepared from cells from the villus and crypt areas, utilizing a continuous sucrose gradient. In the villus cells, Na:H exchange activity was found associated with both the brush border and basolateral membrane, whereas, in crypt cells, Na:H exchange activity was only found on the basolateral membrane. Cl:HCO3 exchange activity was found only on the brush border membrane, in both villus and crypt cells. These studies suggest functional heterogeneity in ion transport between villus and crypt cells.
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PMID:Membrane distribution of sodium-hydrogen and chloride-bicarbonate exchangers in crypt and villus cell membranes from rabbit ileum. 284 68

Varieties of market cheese were analyzed for alkaline phosphatase by the modified rapid colorimetric method of the American Public Health Association (APHA) and the official AOAC method, 16.304-16.306. In the APHA method, 5 g cheese (pH less than 7.0) is macerated with 2 mL 1:1 carbonate buffer, or 2 mL water (for cheese with pH greater than 7.0). Addition of 0.1 mL magnesium acetate (1 mg magnesium) to test portions of cheese extracts yielded reproducible and quantitative recovery of added phosphatase. In the AOAC method, macerating 0.5 g cheese with 1 mL borate buffer before adding milk phosphatase improved recovery among cheeses. Addition of magnesium ion increased phosphatase activity in some cheeses. Phosphatases in blue mold-ripened and Swiss cheeses were inactivated by heat faster than was milk phosphatase, yet milk phosphatase added to various soft cheeses was completely inactivated at 60 degrees C for 10 min. The lability of phosphatase was due to the heat-denaturing effect of NaCl present in finished cheeses. Some Mexican style soft cheeses contained both heat-labile and heat-stable phosphatases. These data suggest that the phosphatase test to differentiate milk and microbial phosphatases on the basis of repasteurization and analysis of cheese is no longer valid.
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PMID:Evaluation of APHA and AOAC methods for phosphatase in cheese. 285 1

Brush-border membrane fractions were isolated from rat duodenum. Purity and integrity of the fraction was confirmed by electron microscopy, enzymic analysis and demonstration of Na+-dependent glucose uptake. The membranes were enriched 15-fold in alkaline phosphatase and alpha-glucosidase and 6-fold in HCO3--ATPase activities. Assays of latent activity indicated that these enzymes were predominantly localised to the external aspect of the microvillus membrane. The enzymes were solubilised and subjected to analysis by gel filtration, ion exchange and phenylboronate chromatography. No separation of alkaline phosphatase and HCO3--ATPase was obtained and it is suggested that they reflect the same enzyme activity. The apparent activation by HCO3- was investigated, and was found to be due to shifts in the pH dependency of the activity due to changes in ionic strength.
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PMID:Studies on the localization and properties of rat duodenal HCO3--ATPase with special relation to alkaline phosphatase. 295 Sep 30

Bicarbonate-stimulated Mg2+ dependent ATPase activity was demonstrated both biochemically and cytochemically, in brush border membranes from rat, rabbit and guinea pig duodenum. There was no correlation between enzyme activity and basal HCO3- secretion rates in the different species. The concentration of HCO3- necessary for optimal stimulation of ATPase activity, degree of stimulation and total activity was higher in the rat than in other species. Activity was higher in rat duodenum than in the ileum. This is consistent with the proposed electrogenic HCO3- secretion in the duodenum. Distribution of activities of alkaline phosphatase and HCO3(-)-stimulated Mg2+-ATPase along the duodenal villus showed significant differences, suggesting that the two activities reflect, at least in part, distinct enzymes.
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PMID:Biochemical and cytochemical comparison of intestinal bicarbonate-stimulated Mg2+ dependent ATPase and alkaline phosphatase activities in rat, rabbit and guinea pig. 295 98

The maximum activity (Vmax) of acid phosphomonoesterase (E.C.3.1.3.2.) at pH 5.5 and 37 degrees C was found to be 2.68 +/- 0.25 and 3.85 +/- 0.24 mu moles phenol mg protein-1 min-1 in male and female Bunostomum trigonocephalum, respectively. The Vmax of alkaline phosphomonoesterase (E.C.3.1.3.1) at pH 10.0 and 37 degrees C was 0.75 +/- 0.04 and 1.15 +/- 0.05 mu moles phenol mg protein-1 min-1 in male and female B. trigonocephalum, respectively. The Michaelis constant (Km) values were 10.25 mM and 11.76 mM for acid and 8.69 mM and 9.09 mM for alkaline phosphomonoesterase in male and female worms, respectively. Enzymal activities were optimum at 7.0 and 9.0% enzyme concentrations, at incubation periods of 60 and 20 min and at temperatures of 50 and 45 degrees C for acid and alkaline phosphomonoesterases, respectively. Dialysis in distilled water decreased the activity of both enzymes, while only acid phosphomonoesterase activity increased in citrate buffer (pH 5.5) and alkaline phosphomonoesterase activity in carbonate buffer (pH 10.0).
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PMID:Studies on kinetic properties of non-specific phosphomonoesterases in the sheep nematode, Bunostomum trigonocephalum Rudolphi, 1808. 302 83

Purified epithelial basolateral membrane vesicles were prepared from lobster hepatopancreas by sorbitol gradient centrifugation. Na+-K+-adenosinetriphosphatase, alkaline phosphatase, and cytochrome-c oxidase enzyme activities in the final membrane preparation were enriched 9.6-, 1.4-, and 0.4-fold, respectively, compared with their activities in the original tissue homogenate. Vesicle osmotic reactivity was demonstrated using 60-min equilibrium 36Cl uptake experiments at a variety of transmembrane osmotic gradients. 36Cl uptake into vesicles preloaded with HCO3 was significantly greater than into vesicles lacking HCO3. This exchange process was stimulated by a transmembrane proton gradient (internal pH greater than external pH). Proton-gradient-dependent Cl-HCO3 exchange was potential sensitive and stimulated by an electrically negative vesicle interior. 36Cl influx (4-s exposures) into HCO3-loaded vesicles occurred by the combination of 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid sensitive, carrier-mediated transfer and "apparent diffusion." 36Cl influx was a hyperbolic function of both internal [HCO3] and internal [Cl]. The two internal anions displayed a 100-fold difference in apparent affinity constants with HCO3 being strongly preferred. 36Cl influx was stimulated more by preloaded monovalent than by divalent anions. Na was an inhibitor of proton-dependent anion antiport, whereas K had no effect. A model for HCl-HCO3 antiport is suggested that employs combined transmembrane concentration gradients of Cl and HCO3 to power anion exchange and transfer protons against a concentration gradient.
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PMID:Proton-stimulated Cl-HCO3 antiport by basolateral membrane vesicles of lobster hepatopancreas. 303 81


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