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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Water-suppressed proton nuclear magnetic resonance spectroscopy of plasma had been proposed as a technique for detecting malignant tumors although its general diagnostic value is widely contested. To assess its diagnostic value in screening for breast cancer, we collected and analyzed 108 plasma samples from healthy women and women with breast disorders, mainly adenocarcinomas. No significant differences were found between controls and patients when average methylene-methyl linewidths were compared. Significant differences, however, were observed when methylene linewidths were compared. Unfortunately, the marked overlapping of both groups greatly reduced the possible diagnostic value of the technique. Among the various biochemical parameters analyzed for each plasma sample--triglyceride, total cholesterol and HDL cholesterol concentration, altered levels of carcinoembryonic antigen, phosphohexose isomerase, 5'-nucleotidase and phosphatase alkaline in patient samples, and estrogen and progesterone receptors of tumors--only triglyceride concentrations presented a clear inverse linear correlation with methylene linewidths.
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PMID:Study of the ability of proton nuclear magnetic resonance spectroscopy of human plasma to differentiate between controls and breast cancer patients. 838 28

The hepatoprotective activity of Picroliv, a standardized iridoid glycoside fraction of Picrorhiza kurroa, has been investigated by studying the protection of biochemical and histological changes induced in livers of rats given single oral doses (7 mg/kg) of aflatoxin B1. Administration of aflatoxin B1 resulted in a significant increase in 5'-nucleotidase, r-glutamyl transpeptidase, acid ribonuclease, total lipids, cholesterol and lipid peroxides in liver and transaminases, alkaline phosphatase and bilirubin in serum. However, the activity of glucose 6-phosphatase and levels of cytochrome P450, cytochrome b5, DNA, RNA, proteins and glycogen in liver and total proteins in serum decreased. The liver histology showed ballooned hepatocytes, degeneration, microvesicular fat, focal necrosis, bile duct hyperplasia and proliferation of oval and spindle cells in portal tracts. When Picroliv (25 mg/kg x 7 days) was given to aflatoxin B1 toxicated rats, the majority of the biochemical and histological changes were significantly protected. The findings indicate a hepatoprotective activity of Picroliv against aflatoxin B1 toxicity in rats.
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PMID:Picroliv protects against aflatoxin B1 acute hepatotoxicity in rats. 847 62

The interaction of tumor cells with extracellular-matrix components is suspected to play an important role in tumorigenesis induction. The tumorigenicity of a poorly tumorigenic human colon-adenocarcinoma cell line (BCS-TC2) was induced by co-injection with Matrigel. A new cell sub-line, BCS-TC2.1, was isolated and established from these tumors. Implantation of these cells in nude mice in the absence of Matrigel-generated tumors which allowed the establishment of another tumorigenic cell sub-line, BCS-TC2.2. Matrigel and laminin, but not collagens, promote the tumorigenicity of BCS-TC2 cells, probably due to specific interactions of a pre-existing minor cell sub-population with laminin, which facilitate the initial growth of these cells in vivo. Cytogenetic analysis reveals that both sub-lines originate from the parental one, but a new marker in chromosome 9 is observed. These sub-lines present a lower degree of differentiation, as deduced from the lower CEA content, 5'-nucleotidase and alkaline-phosphatase activities. No variation is observed in the mRNA and protein expression of the 67-kDa laminin-binding protein. However, an increase in beta1 integrins and a parallel decrease in beta4 integrin were detected. Thus, the new sub-lines, compared to the parental cells, present karyotypic and phenotypic differences such as the expression of a distinctive integrin pattern. This system represents a useful model for understanding the development and progression of tumorigenicity in cancer cells.
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PMID:Characterization of tumorigenic sub-lines from a poorly tumorigenic human colon-adenocarcinoma cell line. 878 56

Subcellular fractions of rat brain were used to determine the subcellular localization of ryanodine receptors. [3H]Ryanodine binding in purified cortical, cerebellar and hippocampal synaptosomes was up to 3.6-fold higher compared with mitochondrial fractions. The density of sites (Bmax) in hippocampal mossy fiber synaptosomes (249 fmol/mg protein) was 3.7-fold greater than in cortical synaptosomes (67 fmol/mg protein) and binding affinity was approximately 2-fold greater in the former (KD, 6.1 nM) than the latter (KD, 3.1 nM). At single sub-saturating concentrations of [3H]ryanodine, binding was 1.6-fold higher in mossy fibers compared with total hippocampal synaptosomes. [3H]Ryanodine binding sites were distributed similarly in subfractions of cortical synaptosomes and microsomes from discontinuous sucrose density gradients. An enrichment of sites was found in the lightest fractions containing the lowest activities of plasma membrane (5'-nucleotidase) and endoplasmic reticulum (glucose 6-phosphatase) enzyme markers when data for microsomal and synaptosomal subfractions were expressed as activity/binding per mg protein and when data for synaptosomal subfractions were expressed as a percentage of total activity/binding in collected fractions. Thus, ryanodine receptors appear to be concentrated in presynaptic terminals where they may play a major role in neurotransmitter release, and appear to be localized either in a specialized endoplasmic reticulum subcompartment or a distinct subcellular organelle.
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PMID:Subcellular localization of ryanodine receptors in rat brain. 886 7

In the present study, we demonstrate the activity of several phosphatases ultrastructurally in long-term (up to 24 months) cold-stored (-80 degrees C) rat tissues. Phosphatase activity was histochemically studied with the use of unfixed cryostat sections in combination with low temperature (4 degrees C) incubation conditions in order to prevent inactivation of enzyme activity and to limit the loss of ultrastructure. 5'-Nucleotidase activity was observed at plasma membranes, mainly at bile canalicular membranes of hepatocytes in liver. Thiamine pyrophosphatase activity was detected not only in trans side cisternae but also in medial and cis side cisternae of Golgi complexes in the parotid gland. Glucose-6-phosphatase activity was localized in endoplasmic reticulum as well as at the outer membrane of the nuclear envelope. Acid phosphatase reaction product was found in lysosomes. Furthermore, the localization patterns of 5'-nucleotidase and thiamine pyrophosphatase activity were compared with those obtained after different fixation procedures such as immediate chemical fixation of tissues or fixation of tissues after freezing and thawing. The results showed similar localization patterns of these enzymes after the different pretreatments. However, with respect to the ultrastructural morphology, some damage was observed in unfixed material after incubation. It can be concluded that the procedure described here enables ultrastructural localization of activity of phosphatases in long-term cold-stored tissues. This procedure will be useful for a retrospective study on archival material when histochemical parameters are needed.
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PMID:Ultrastructural localization of activity of phosphatases by low temperature incubation of unfixed cryostat sections. 889 76

ATPase activity has been located on the external surface of Leishmania tropica. Since Leishmania is known to have an ecto-acid phosphatase, in order to discard the possibility that the ATP hydrolysis observed was due to the acid phosphatase activity, the effect of pH in both activities was examined. In the pH range from 6.8 to 8.4, in which the cells were viable, the phosphatase activity decreased, while the ecto-ATPase activity increased. To confirm that the observed ATP hydrolysis was promoted by neither phosphatase nor 5'-nucleotidase activities, a few inhibitors for these enzymes were tested. Vanadate and NaF strongly inhibited the phosphatase activity; however, no effect was observed on ATPase activity. Neither levamizole nor tetramizole, two specific inhibitors of alkaline phosphatases, inhibited this activity. The lack of response to ammonium molybdate indicated that 5'-nucleotidase did not contribute to the ATP hydrolysis. Also, the lack of inhibition of the ATP hydrolysis by high concentrations of ADP at nonsaturating concentrations of ATP discarded the possibility of any ATP diphosphohydrolase activity. The ATPase here described was stimulated by MgCl2 but not by CaCl2. In the absence of divalent metal, a low level of ATP hydrolysis was observed, and CaCl2 varying from 0.1 to 10 mM did not increase the ATPase activity. At 5 mM ATP, half-maximal stimulation of ATP hydrolysis was obtained with 0.29 +/- 0.02 mM MgCl2. The apparent K(m) for Mg-ATP2- was 0.13 +/- 0.01 mM and free Mg2+ did not increase the ATPase activity. ATP was the best substrate for this enzyme. Other nucleotides such as ITP, CTP, GTP, UTP, and ADP produced lower reaction rates. To confirm that this Mg-dependent ATPase was an ecto-ATPase, an impermeant inhibitor, 4,4'-diisothiocyanostylbene-2,2'-disulfonic acid was used. This amino/sulfhydryl-reactive reagent did inhibit the Mg-ecto-ATPase activity in a dose-dependent manner (I0.5 = 27.5 +/- 1.8 microM).
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PMID:Mg-dependent ecto-ATPase activity in Leishmania tropica. 914 51

Few studies have examined tubular function after subtotal nephrectomy (Nx) and conservative treatments. The effects of 70% and 80% Nx (associated with dietary phosphate restriction in the latter case) on the apical brush border membrane (BBM) enzymes 5'-nucleotidase, gamma glutamyl-transferase and alkaline-phosphatase, and one BBM Na-phosphate cotransporter (NaPi-2) were studied in rats after a six week period. Changes in activity and mRNA abundance of the BBM enzymes and in NaPi-2 protein and mRNA abundance were compared with changes in the distal markers of Na,K-ATPase activity and epidermal growth factor (EGF) production. The activity, but not the mRNA of BBM enzymes, was moderately reduced by the 70% Nx. Both the mRNA and activity of gamma glutamyl-transferase and alkaline-phosphatase were decreased in the 80% Nx, and the NaPi-2 mRNA, protein and Na,K-ATPase activities were also reduced. These effects (except for 5'nucleotidase and Na,K-ATPase) were partly reversed by phosphate restriction. Overproduction of EGF occurred after the 70% Nx, was blunted in the 80% Nx, and then partially restored by phosphate restriction. Aggravation of tubular alteration was associated with enhanced renal hyperplasia (increased DNA mass), reduced GFR and hyperphosphatemia, and high PTH levels, but reduced cAMP excretion. Improvement following phosphate restriction was associated with reduced hyperplasia and lowering of phosphatemia and PTH levels. These data demonstrate that Nx selectively affected BBM function through transcriptional changes that were partially reversed by phosphate restriction. Regulatory factors involved in these changes may include intracellular phosphate content and growth factors, but not the PTH effects that are impaired in chronic renal failure.
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PMID:Subtotal nephrectomy alters tubular function: effect of phosphorus restriction. 940

Ultrastructural and light microscopic cytochemical methods were used to study the distribution and changes in distribution of three phosphatase enzymes: 5'-nucleotidase (5N); thiamine pyrophosphatase (TPP); and adenosine triphosphatase (ATP) in the rat endometrium during early pregnancy up to the time of blastocyst attachment. The authors were particularly interested in changes in the apical plasma membrane and reaction product for all three enzymes was clearly localized along this membrane especially on day 1 of pregnancy. However, the three enzymes showed markedly different patterns of organization of reaction product at later times during early pregnancy. 5N, while showing a continuous lining along the microvilli on day 1 was virtually undetectable by day 6. TPP was also strongly present apically on day 1, but reaction product was not always found as a continuous lining. Again, by day 6, there was no presence of this enzyme along the apical surface. ATP differed from the other two in that it produced a strong, and relatively unchanged reaction product along the apical plasma membrane from day 1 through to day 6 of pregnancy. The changes in distribution of these enzymes was particularly obvious at the electron microscopic level and we consider their contribution to the process of 'plasma membrane transformation' of early pregnancy.
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PMID:Differential alterations in the distribution of three phosphatase enzymes during the plasma membrane transformation of uterine epithelial cells in the rat. 1052 45

In this work, we describe the ability of living cells of Entamoeba histolytica to hydrolyze extracellular ATP. In these intact parasites, whose viability was determined by motility and by the eosin method, ATP hydrolysis was low in the absence of any divalent metal (78 nmol P(i)/h/10(5) cells). Interestingly, in the presence of 5 mM MgCl(2) an ecto-ATPase activity of 300 nmol P(i)/h/10(5) cells was observed. The addition of MgCl(2) to the extracellular medium increased the ecto-ATPase activity in a dose-dependent manner. At 5 mM ATP, half-maximal stimulation of ATP hydrolysis was obtained with 1.23 mM MgCl(2). Both activities were linear with cell density and with time for at least 1 h. The ecto-ATPase activity was also stimulated by MnCl(2) and CaCl(2) but not by SrCl(2), ZnCl(2), or FeCl(3). In fact, FeCl(3) inhibited both Mg(2+)-dependent and Mg(2+)-independent ecto-ATPase activities. The Mg(2+)-independent ATPase activity was unaffected by pH in the range between 6.4 and 8. 4, in which the cells were viable. However, the Mg(2+)-dependent ATPase activity was enhanced concomitantly with the increase in pH. In order to discard the possibility that the ATP hydrolysis observed was due to phosphatase or 5'-nucleotidase activities, several inhibitors for these enzymes were tested. Sodium orthovanadate, sodium fluoride, levamizole, and ammonium molybdate had no effect on the ATPase activities. In the absence of Mg(2+) (basal activity), the apparent K(m) for ATP(4-) was 0.053 +/- 0.008 mM, whereas at saturating MgCl(2) concentrations, the corresponding apparent K(m) for Mg-ATP(2-) for Mg(2+)-dependent ecto-ATPase activity (difference between total and basal ecto-ATPase activity) was 0.503 mM +/- 0.062. Both ecto-ATPase activities were highly specific for ATP and were also able to hydrolyze ADP less efficiently. To identify the observed hydrolytic activities as those of an ecto-ATPase, we used suramin, a competitive antagonist of P(2) purinoreceptors and an inhibitor of some ecto-ATPases, as well as the impermeant agent 4'-4'-diisothiocyanostylbenzene-2'-2'-disulfonic acid. These two reagents inhibited the Mg(2+)-independent and the Mg(2+)-dependent ATPase activities to different extents, and the inhibition by both agents was prevented by ATP. A comparison among the ecto-ATPase activities of three amoeba species showed that the noninvasive E. histolytica and the free-living E. moshkovskii were less efficient than the pathogenic E. histolytica in hydrolyzing ATP. As E. histolytica is known to have a galactose-specific lectin on its surface, which is related to the pathogenesis of amebiasis, galactose was tested for an effect on ecto-ATPase activities. It stimulated the Mg(2+)-dependent ecto-ATPase but not the Mg(2+)-independent ATPase activity.
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PMID:Ectonucleotide diphosphohydrolase activities in Entamoeba histolytica. 1070 Mar 86

1. We investigated the effects of pH elevation or depression on adenosine output from buffer-perfused rat gracilis muscle, and kinetic properties of adenosine-forming enzymes, 5'-nucleotidase (5'N) and non-specific phosphatase (PT), and adenosine-removing enzymes, adenosine kinase (AK) and adenosine deaminase (AD), in homogenates of muscle. 2. Depression of the perfusion buffer pH from 7.4 to 6.8, by addition of sodium acetate, reduced arterial perfusion pressure from 8.44 +/- 1.44 to 7.33 +/- 0.58 kPa, and increased adenosine output from 35 +/- 5 to 56 +/- 6 pmol min-1 (g wet wt muscle)-1 and AMP output from 1.8 +/- 0.3 to 9.1 +/- 3.9 pmol min-1 (g wet wt muscle)-1. 3. Elevation of the buffer pH to 7.8, by addition of ammonium chloride, reduced arterial perfusion pressure from 8.74 +/- 0.57 to 6.96 +/- 1.37 kPa, and increased adenosine output from 25 +/- 5 to 47 +/- 8 pmol min-1 (g wet wt muscle)-1 and AMP output from 3.7 +/- 1.1 to 24.6 +/- 6.8 pmol min-1 (g wet wt muscle)-1. 4. Activity of membrane-bound 5'N was an order of magnitude higher than that of either cytosolic 5'N or PT: pH depression reduced the K(m) of 5'N, which increased its capacity to form adenosine by 10-20% for every 0.5 unit decrease inpH within the physiological range. PT was only found in the membrane fraction: its contribution to extracellular adenosine formation increased from about 5% at pH 7.0 to about 15% at pH 8.0. 5. Cytosolic 5'N had a low activity, which was unaffected by pH; the rate of intracellular adenosine formation was an order of magnitude lower than the rate of adenosine removal by adenosine kinase or adenosine deaminase, which were both exclusively intracellular enzymes. 6. We conclude that (i) adenosine is formed in the extracellular compartment of rat skeletal muscle, principally by membrane-bound 5'N, where it is protected from enzymatic breakdown; (ii) adenosine is formed intracellularly at a very low rate, and is unlikely to leave the cell; (iii) enhanced adenosine formation at low pH is driven by an increased extracellular AMP concentration and an increased affinity of membrane-bound 5'N for AMP; (iv) enhanced adenosine formation at high pH is driven solely by the elevated extracellular AMP concentration, since the catalytic capacity of membrane 5'N is reduced at high pH.
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PMID:Evidence for control of adenosine metabolism in rat oxidative skeletal muscle by changes in pH. 1071 70


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