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)

The agent 2-chlorodeoxyadenosine (2-CdA) has chemotherapeutic activity in hairy cell leukemia (HCL) and in refractory chronic lymphocytic leukemia (CLL). The cytotoxic activity of 2-CdA requires the intracellular accumulation of 2-CdA nucleotides. Deoxycytidine kinase (dCK) and cytoplasmic 5'-nucleotidase (5'-NT) are the principal enzymes that phosphorylate 2-CdA and dephosphorylate 2-CdA 5'-monophosphate, respectively. The net accumulation of 2-CdA nucleotides may therefore depend on both dCK and 5'-NT. The purpose of the present experiments was to determine if there is a relationship between pretreatment levels of dCK and 5'-NT in HCL and in CLL cells, and the clinical outcome of 2-CdA treatment. As measured by a direct immunoassay for dCK in 25 CLL patients, and by a 5'-NT activity assay in 23 patients, mean dCK levels were significantly higher in 2-CdA responders than in nonresponders (P < .01), whereas mean 5'-NT levels were significantly lower in 2-CdA responders than in nonresponders (P < .05). Mean dCK levels were higher in six HCL 2-CdA responders than in one nonresponder, whereas mean 5'-NT levels were lower in the 2-CdA responders than in the nonresponder. These results suggest that both dCK and 5'-NT are determinants of 2-CdA responsiveness.
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PMID:Relationship of deoxycytidine kinase and cytoplasmic 5'-nucleotidase to the chemotherapeutic efficacy of 2-chlorodeoxyadenosine. 809 16

Capacity for ATP resynthesis during recovery from ischemia or hypoxia is limited to the size of the adenine nucleotide pool, which is determined in part by the activity of cytosolic 5'-nucleotidase (5'-NT): AMP-->adenosine plus inorganic phosphate (Pi). To define in vivo regulation of 5'-NT, we used the tools of 31P nuclear magnetic resonance (NMR), spectroscopy and chemical assay to measure the substrates (AMP), products (Pi, adenosine, and its catabolites), and inhibitors (Pi and H+) of 5'-NT in isolated perfused rat hearts exposed to hypoxia (where pH remains near 7) and no flow, global ischemia (where pH falls to 6.1). We estimated 5'-NT reaction velocity, assessed the relative contributions of Pi and H+ to enzyme inhibition, and defined the consequences of changes in 5'-NT activity on ATP resynthesis after hypoxia and ischemia. We conclude that (a) 5'-NT is activated during hypoxia and early ischemia but is inhibited during prolonged ischemia, (b) H+ (pH < 6.2) is a potent inhibitor of 5'-NT, and (c) differences in AMP accumulation are sufficient to explain the differences in the capacity for net ATP resynthesis in ischemic and hypoxic tissue. These observations have implications for our understanding of heterogeneity of ischemic injury and myocardial protection during ischemia.
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PMID:Acidosis during ischemia promotes adenosine triphosphate resynthesis in postischemic rat heart. In vivo regulation of 5'-nucleotidase. 828 12

HTK (histidine-tryptophane-ketoglutarate) organ preservation solution has been shown to be effective in human kidney transplantation, but the efficacy of HTK for extended liver preservation has not been determined. In this study, canine livers were preserved in HTK and compared with livers preserved in University of Wisconsin solution. First, the right and left liver lobes in dogs were flushed separately with cold HTK and UW, respectively, according to a double-flush method. After splitting the liver, the right and left lobes were stored at 4 degrees C in either solution for 24 hr and 48 hr and assessed microscopically for parenchymal cell swelling, and enzyme histochemically for 5'-nucleotidase (5'-NT) as a marker of ischemic liver injury. Unlike livers preserved in UW (n = 5), HTK-preserved livers (n = 5) showed progressive parenchymal cell swelling after 24-hr and 48-hr storage. The 5'-NT scores in HTK livers were lower than in UW livers, indicating increased storage injury (0-5% and 66-85% in HTK- and UW-preserved livers, respectively, after 48-hr storage). Second, graft function was tested in an orthotopic liver transplantation model in the dog. Whole livers were flushed in situ with cold HTK or UW and stored at 4 degrees C for 24 hr or 48 hr. Liver grafts stored in HTK were not washed out prior to reflow in the recipient, in contrast to grafts stored in UW. Livers preserved for 24 hr using HTK showed life-supporting function after transplantation (n = 5, survival 12 hr-8 days). All grafts preserved for 48 hr in HTK did not function (n = 5, survival < 10 hr). UW-preserved grafts all functioned after 24-hr storage (n = 5, survival > 6 days), as well as after 48-hr storage (n = 6, survival > 6 days). Peak serum glutamic oxaloacetic transaminase (SGOT) values after transplantation of 24-hr and 48-hr HTK-preserved livers did not differ from peak SGOT values of UW-preserved livers after similar preservation times. In conclusion, UW solution is more effective than HTK solution in extended preservation of canine liver grafts: 24-hr storage of livers preserved with HTK solution is feasible, whereas 48-hr storage results in a nonfunctioning graft.
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PMID:Preservation of canine liver grafts using HTK solution. 831 May 2

1. Specific activities of adenosine deaminase, purine nucleoside phosphorylase, adenosine kinase, 5'-nucleotidase, S-adenosyl-L-homocysteine hydrolase, AMP deaminase, adenine phosphoribosyl transferase, and hypoxanthine phosphoribosyl transferase were analyzed in human CD4 T-lymphocyte subsets. 2. CD4 Leu 8- (helper/inducer) and CD4 Leu 8+ (suppressor/inducer) subpopulations were obtained by panning or fluorescence activated cell sorting techniques using specific monoclonal antibodies. 3. A 45% decrease of 5'-NT AMP activity in the CD4 Leu 8- cells (suppressor/inducer) compared with CD4 total cell population. 4. No statistical significant differences in enzyme activity were found between the subsets analyzed in other purine enzymes. 5. These results suggest that the distribution of purine metabolic enzymes is homogeneous in CD4 Leu 8- and CD4 Leu 8+ T-lymphocyte subpopulations.
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PMID:Analysis of purine metabolic enzymes in human CD4 Leu 8- and CD4 Leu 8+ lymphocyte subpopulations. 844 17

The activity and localization of the plasma membrane-bound enzyme 5'-nucleotidase (5'-NT) in liver tissue are sensitive parameters of ischemic damage. The value of 5'-NT as a marker of liver graft viability was studied in relation to liver preservation. In six mongrel dogs, the main right and left branches of the portal vein were cannulated and flushed separately in situ with cold University of Wisconsin (UW) solution and Euro-Collins (EC) solution, respectively. After hepatectomy, the right and left liver lobes were split and stored at 5 degrees C in either of the two solutions. 5'-NT activity was demonstrated in cryostat sections of liver tissue using the lead salt method. After 48 h of storage in EC solution, the 5'-NT score had decreased to 31% +/- 16% (n = 6), whereas in UW solution the 5'-NT score was 76% +/- 10% (n = 6). Significantly (P < 0.05) higher 5'-NT scores were also found after 24-h and 72-h preservation times in UW versus EC solutions. This result is in keeping with the higher preservation tolerance of liver grafts preserved in UW solution. The 5'-NT assay was studied in relation to graft function in orthotopic liver transplantation experiments in dogs. All dogs with liver grafts preserved in UW solution for 24 h (n = 4) and 48 h (n = 3) survived (> 5 days). Pretransplant 5'-NT scores ranged from 61% to 100%. The 72-h-preserved livers (n = 5) did not show life-supporting function.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An in vitro method for comparing the efficacy of two preservation solutions in one canine liver using the 5'-nucleotidase assay. 845 36

The activity of acetylcholinesterase (AChE), adenylate cyclase (AC), 5'-nucleotidase (NT), Na+, K(+)-ATPase, as well as the contents of phospholipids (PL) and gangliosides (G) per mg of protein in homogenate, crude membrane (P2) fraction, and synaptosomes from the sensorimotor cortex of the right and left hemispheres of rat brain were analyzed under normal and hypoxic conditions. The authors found that under normal physiological conditions there are no significant differences of the studied parameters in homogenates of sensorimotor cortex from the right and left hemispheres. In P2 fractions, and especially in preparations of synaptosomes from the right and left cortex, differences in the activity of 5'-NT and AC were found. Hypoxia (pO2 = 7.8%) was shown to alter studied parameters (AChE, AC, Na+, K(+)-ATPase activity, and PL content) mainly in the right hemisphere.
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PMID:Hypoxic hypoxia induces different biochemical changes in the cortex of the right and left hemispheres of rat brain. 853 26

The human leukocyte surface Ag CD38 was recently identified as a nicotinamide adenine dinucleotide (NAD)(+)-glycohydrolase ecto-enzyme, degrading NAD into nicotinamide and ADP-ribose. We show here that expression of CD38 is increased in the Jurkat T cell line after treatment with agents that augment intracellular cAMP, with the permeant cAMP analogue dibutyryl-cAMP (db-cAMP), and also with PMA, which activates protein kinase C. Treatment of human PBL T cells with db-cAMP or submitogenic doses of PMA also increased CD38 expression. Two other nucleotide-hydrolyzing activities were induced on the T cell surface concomitantly with CD38: the human PC-1 molecule, a nucleotide phosphodiesterase/pyrophosphatase that produces AMP from NAD or ADP-ribose, and a nucleotidase that produces adenosine from AMP, but which may be distinct from the CD73 5'-nucleotidase. All three enzymes were up-regulated after stimulation of human peripheral blood T cells with PHA. The coordinated regulation of these ecto-enzymes suggested that, besides a possible signaling function, they may recycle extracellular NAD by degrading it to adenosine and nicotinamide, which can be taken up by cells. In support of this hypothesis, db-cAMP-treated Jurkat cells could degrade extracellular NAD for de novo synthesis of purines, while untreated cells could not. Activated lymphocytes are often located in tissues in which cell death is common. It is suggested that the coordinated expression of these enzymes may allow activated T cells to re-use NAD and nucleotides from dead cells.
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PMID:Coordinated regulation in human T cells of nucleotide-hydrolyzing ecto-enzymatic activities, including CD38 and PC-1. Possible role in the recycling of nicotinamide adenine dinucleotide metabolites. 875 17

Alanine aminotransferase (AlAT), aspartate aminotransferase (AspAT), adenosine deaminase (ADA) and 5'-nucleotidase (5'-NT) activities were studied in the rat intestine smooth muscles after 24 and 48 hours of fasting. It was found that fasting evoked a significant decrease in ADA and increase in 5'-NT activities in all intestinal segments analysed. A dual effect of fasting was noted for AspAT and AlAT; after first 24h of fasting the activities of both enzymes decreased and increased again when fasting was continued to 48h. We conclude that during fasting an adaptive response occurs in the smooth muscles of intestine and this may be a part of systemic adaptation to fasting.
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PMID:Effect of fasting on some enzymatic activities in the muscle layer of intestine in the rat. 883 8

Both ischemic preconditioning and pretreatment with the endotoxin derivative monophosphoryl lipid A (MLA) protect the heart against infarction, yet the cellular mechanisms responsible for the cardioprotection achieved with either intervention are unknown. Using pentobarbital-anesthetized dogs, we tested the hypothesis that increased activity of 5'-nucleotidase (5'-NT), the enzyme that catalyzes the formation of adenosine from AMP, may play a role. Twenty-two dogs underwent 1 h of coronary occlusion and 4 h of reperfusion: eight controls received no intervention, seven animals were preconditioned with four 5-min episodes of brief ischemia, and seven received MLA (35 micrograms/kg iv) 24 h previously. Collateral blood flow was measured by injection of radiolabeled microspheres, infarct size was delineated by tetrazolium staining, and myocardial 5'-NT activities were measured by quantifying the release of adenosine from AMP. Despite comparable values of collateral blood flow in all groups, infarct size was reduced in preconditioned and MLA-treated dogs vs. controls. In addition, 5'-NT activities were increased throughout the heart with preconditioning and MLA treatment. However, single and multivariate regression analyses revealed no correlation between infarct size and 5'-NT activities for either treatment group. In fact, in the preconditioned cohort, animals with the highest enzyme activities developed the largest infarcts. This dissociation between infarct size and 5'-NT suggests that increased activity of 5'-NT is not the mechanism by which preconditioning or MLA treatment protects the canine heart against infarction.
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PMID:Cardioprotection with ischemic preconditioning and MLA: role of adenosine-regulating enzymes? 885 35

Adenosine has potent immunosuppressive activity. Since the source of adenosine and the mechanism of its release in the immune system is largely unknown and may vary according to cell type, we have evaluated the relationship between adenosine metabolism and the enzymatic activities and mRNA levels of adenosine-metabolizing enzymes in myeloid and lymphoid cell lines. Induction of HL-60 cell differentiation along the macrophage lineage by PMA resulted in a reduction in the activities of adenosine deaminase (ADA), adenosine kinase (AK), and inosine monophosphate-specific cytosolic 5'-nucleotidase and an elevation of ecto-5'-nucleotidase (ecto-5'-NT). These changes were accompanied by an elevation of ecto-5'-NT mRNA and a decrease in ADA and AK mRNAs in a time-dependent fashion. Comparison of AK and ADA mRNA levels in several other leukemic cell lines revealed generally similar responses to PMA with much stronger suppression in immature T cells than in B cells. The metabolism of adenosine either through phosphorylation (AK) or deamination (ADA) was reduced in PMA-stimulated cells. Furthermore, the cumulative changes in enzyme expression resulted in a 2.5-fold increase in intracellular adenosine formation in PMA-stimulated cells. The inhibition of AK by 5'-iodotubercidin further increased adenosine formation by 6-fold over that in untreated cells. In accord with the increase in ecto-5'-NT activity, extracellular AMP dephosphorylation increased dramatically, but there was no increase in extracellular ATP degradation. These results indicate that a coordinated shift in adenosine-metabolizing enzyme levels during PMA-induced HL-60 cell differentiation is accompanied by a decrease in adenosine uptake and an increase in adenosine release.
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PMID:Adenosine metabolism during phorbol myristate acetate-mediated induction of HL-60 cell differentiation: changes in expression pattern of adenosine kinase, adenosine deaminase, and 5'-nucleotidase. 914 13


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